18521	----	AN EXPOSITORY OUTLINE OF THE "VESTIGES OF THE NATURAL HISTORY OF CREATION;" WITH A COMPREHENSIVE AND CRITICAL ANALYSIS OF THE ARGUMENTS BY WHICH THE EXTRAORDINARY HYPOTHESES OF THE AUTHOR ARE SUPPORTED AND HAVE BEEN IMPUGNED, WITH THEIR BEARING UPON THE RELIGIOUS AND MORAL INTERESTS OF THE COMMUNITY. WITH A NOTICE OF THE AUTHOR'S "EXPLANATIONS:" A SEQUEL TO THE VESTIGES. * * * * * _Originally printed in a Supplement of_ THE ATLAS _Newspaper of August 30 and December 20, 1845._ * * * * * LONDON: EFFINGHAM WILSON, ROYAL EXCHANGE. J. VINCENT, OXFORD; G. ANDREWS, DURHAM; J. TEPPELL, NORWICH; BRODIE AND CO., SALISBURY. A. AND C. BLACK, EDINBURGH; D. ROBERTSON, GLASGOW; A. BROWN AND CO., ABERDEEN. W. CURRY, JUN., AND CO., DUBLIN. 1846. ADVERTISEMENT. * * * * * The following tractate first appeared in the form of a literary review in a supplement of the ATLAS; but two impressions of that journal having been long since exhausted, and inquiries still continuing numerous and urgent, the proprietor has granted permission for the article to be reprinted in a separate, more convenient, and perhaps enduring vehicle than that of a newspaper. Few works of a scientific import have been published that so promptly and deeply fixed public attention as the _Vestiges of Creation_, or elicited more numerous replies and sharper critical analysis and disquisition. Upon so vast a question as the evolution of universal creation differences of opinion were natural and unavoidable. Many have disputed the accuracy of some of the author's facts, and the sequence and validity of his inductive inferences; but few can withhold from him the praise of a patient and intrepid spirit of inquiry, much occasional eloquence, and very considerable powers of analysis, systematic induction, arrangement and combination. In what follows the leading objects kept in view have been--first, an expository outline of the author's facts and argument; next, of the chief reasons by which they have been impugned by Professor SEDGWICK, Professor WHEWELL, Mr. BOSANQUET, and others who have entered the lists of controversy. These arrayed, the concluding purpose fitly followed of a brief exhibition of the relative strength of the main points in issue, with their bearing on the moral and religious interests of the community. It is the fourth and latest edition that has been submitted to investigation. In this impression the author has introduced several corrections and alterations, without, however, any infringement or mitigation of its original scope and character. More recently appeared his "Explanations," a Sequel to the "Vestiges of the Natural History of Creation;" in which the author endeavours to elucidate and strengthen his former position. This had become necessary in consequence of the number of his opponents, and the inquiry and discussion to which the original publication had given rise. Of this, also, a lengthened review was given in the ATLAS, which has been included; so that the reader will now have before him a succinct outline of a novel and interesting topic of philosophical investigation. In the present reprint a few corrections have been made, and the illustrative table at page 34, and some other additions, introduced. _London, January_ 1, 1846. AN EXPOSITORY OUTLINE OF THE "VESTIGES OF THE NATURAL HISTORY OF CREATION." It rarely happens that speculative inquiries in England command much attention, and the _Vestiges of Creation_ would have probably formed no exception, had it not been from the unusual ability with which the work has been executed. The subject investigated is one of vast, almost universal, interest; for everyone--the low, in common with the high in intellect--find enigmas in creation that they would gladly have unriddled, and promptly gather round the oracle who has boldly stepped forth to cut the knot of their perplexities. The first impression made, too, is favourable. No very striking originality, eloquence, or genius, is displayed; yet there is ingenuity; and though the author betrays the zeal of an advocate, desirous of leading to a determinate and _material_ conclusion, his address, like that of the apostle of temperance, is mostly mild and equable, with occasionally a little gentlemanly fervour to give animation to his discourse. His style is mostly felicitous, sometimes beautiful, lucid, precise, and elevated. In tone and manner of execution, in quiet steadiness of purpose, in the firm, intrepid spirit with which truth, or that which is conceived to be true, is followed, regardless of startling presentments, the _Vestiges_ call to mind the _Mecanique Celeste_, or _Système du Monde_. In caution, as in science, the author is immeasurably inferior to LAPLACE; but in magnitude and boldness of design he transcends the illustrious Frenchman. LAPLACE sought no more than to subject the celestial movements to the formulas of analysis, and reconcile to common observation terrestrial appearances; but our author is far more ambitious--more venturesome in aim--which is nothing less than to lift the veil of ISIS, and solve the phenomena of universal nature. With what success remains to be considered. That great skill and cleverness, that a very superior mastery is evinced, we have conceded, and, we will also add, great show of fairness in treatment and conclusion. No partial opening is made; the great design, in all its extent, is manfully grappled with. The universe is first surveyed, next the mystery of its origin. After ranging through sidereal space, examining the bodies found there, their arrangement, formation, and evolution, the author selects our own planet for especial interrogation. He disembowels it, scrutinizing the internal evidences of its structure and history, and thence infers the causes of past vicissitudes, existing relations, and appearances. These disposed of, the surface is explored, the phenomena of animal and vegetable existence contemplated, and the sources of vital action, sexual differences, and diversities of species assigned. Man, as the supreme head and last work of progressive creation, challenges a distinct consideration; his history and mental constitution are investigated, and the relation in which a sublime reason stands to the instinct of brutes discriminated. The end and purpose of all appropriately form the concluding theme, which finished, the curtain drops, and the last sounds heard are that the name of the Great Unknown will probably never be revealed; that "praise will elicit no response," nor any "word of censure" be parried or deprecated. "Give me," exclaimed ARCHIMEDES, "a fulcrum, and I will raise the earth." "Give me," says the author of the _Vestiges_, "gravitation and development, and I will create a universe." ALEXANDER'S ambition was to conquer a world, our author's is to create one. But he is wrong in saying that his is the "first attempt to connect the natural sciences into a history of creation, and thence to eliminate a view of nature as one grand system of causation." The attempt has been often made, but utterly failed; its results have been found valueless, hurtful--to have occupied without enlarging the intellect, and the very effort has long been discountenanced. Great advances, however, have been made in science since system-making began to be discredited; nature has been perseveringly ransacked in all her domains, and many extraordinary secrets drawn from her laboratory. Astronomy and geology, chemistry and electricity, have greatly extended the bounds of knowledge; still, we apprehend, we are not yet sufficiently armed with facts to resolve into one consistent whole her infinite variety. Efforts at generalization, however, and the systematic arrangement of natural phenomena, are seldom wholly fruitless. If false, they tend to provoke discussion--to lead to active thought and useful research. A solitary truth, though new and useful, rarely obtains higher distinction than to be quietly placed on the rolls of science, while a bold speculation, traversing the whole field of creation, and smoothing all its difficulties, satisfies for the moment, and fixes general attention. Of this the _Vestiges of Creation_ are an example. Without adding to our positive knowledge by a single new discovery, demonstration, or experiment, they have excited more interest than the _Principia_ of NEWTON. From this popular success, if good do not accrue, no great evil need be anticipated. Hypotheses are most hurtful when accredited by an irreversible authority--when erected into a tribunal without appeal, they become the arbitrary dictator in lieu of the handmaid of science. Discussion and invention, in place of being stimulated, are then fettered by them; the human mind is enslaved, as Europe was for centuries by the _Physics_ of ARISTOTLE, and still continues to be in some of the ancient retreats and conservatories of exploded errors. But these form the exceptions, not the rule of the age, which is free and equal inquiry. Errors have ceased to have prescriptive immunities; and mere conjectures, however sanctioned or plausible, if inconsistent with science--with the ascertained facts of experiment and observation, are speedily passed into the region of dreams and chimeras. Whether this will be the fate of our author remains to be proved. The moment selected for his appearance has at least been well chosen. The _Vestiges_ have the air of novelty, a long time having elapsed since any one had the hardihood to propound a new system of Nature. In common with most manifestations of our time, his effort exhibits a marked improvement on the crudities of his predecessors in the same line of architectural ambition. Science has been called to his aid, and the patient ingenuity with which he has sought to make the latest discoveries subservient to his purpose challenges admiration, if not acquiescence. Some of our contemporaries have been warmed into almost theological aversion by the boldness of his conclusions, but we see little cause for fear, and none for bitterness or apprehension. More closely Nature is investigated and deeper the impression will become of her majesty and might. Unlike earthly greatnesses, she loses no power--no grandeur--no fascination--no prestige, by familiarity. The greatest philosophers will always rank among her greatest admirers and most devout and fervent worshippers. Had our author proved all he has assumed our faith would not be lessened, nor our wonder diminished. Whether matter or spirit has been the world's architect, the astounding miracle of its creation is not the less. What does it import whether it resulted direct from the fiat of Omnipotence, or intermediately from the properties He impressed, or the law of development He prescribed? He who gave the law, who infused the energies by which Chaos was transmuted into an organized universe, remains great and inscrutable as ever. It is time, however, that we entered upon a more detailed and closer investigation of the _Vestiges of Creation_. Our purpose is not hastily, and without examination, to deprecate, deny, or controvert; but patiently, and without prejudice, to inquire, to submit faithfully and intelligibly the outlines of a remarkable treatise; describe briefly its scope and bearing, the arguments by which they are supported, and the counter reasons by which they appear to be wholly or partially impugned. Our readers will thus be enabled to appreciate the merits of a controversy, the most comprehensive and interesting that for a lengthened period has occupied the attention of the scientific and intellectual world. For greater clearness of exposition we shall endeavour to follow the order observed by the author in the division and treatment of his subjects, commencing first with the BODIES OF SPACE. The author opens his subject with a brief but luminous outline of the arrangement and formation of the astral and planetary systems of the heavens. He first describes the solar system, of which our earth is a member, consisting of the sun, planets, and satellites with the less intelligible orbs termed comets, and taking as the uttermost bounds of this system the orbit of Uranus, it occupies a portion of space not less than three thousand six hundred millions of miles in diameter. The mind cannot form an exact notion of so vast an expanse, but an idea of it may be obtained from the fact, that, if the swiftest racehorse ever known had began to traverse it at full speed at the time of the birth of MOSES, he would only yet have accomplished half his journey. Vast as is the solar system, it is only one of an infinity of others which may be still more extensive. Our sun is supposed to be a star belonging to a constellation of stars, each of which has its accompaniment of revolving planets; and the constellation itself with similar constellations to form revolving clusters round some mightier centre of attraction; and so on, each astral combination increasing in number, magnitude, and complexity, till the mind is utterly lost in the vain effort to grasp the limitless arrangement. Of the stars astronomers can hardly be said to know anything with certainty. Sirius, which is the most lustrous, was long supposed to be the nearest and most within the reach of observation, but all attempts to calculate the distance of that luminary have proved futile. Of its inconceivable remoteness some notion may be formed by the fact, that the diameter of the earth's annual orbit, if viewed from it, would dwindle into an invisible point. This is what is meant by the stars not having, like the planets, a _parallax_; that is, the earths' orbit, as seen from them, does not subtend a measurable angle. With two other stars, however, astronomers have unexpectedly and recently been more fortunate than with Sirius, and have been able to calculate their distances from the earth. The celebrated BESSEL, and soon afterwards, the late Mr. HENDERSON, astronomer royal for Scotland, were the first to surmount the difficulty that had baffled the telescopic resources of the HERSCHELS. BESSEL detected a parallax of one-third of a second in the star 61 Cygni, and in the constellation of the Centaur HENDERSON found another star whose parallax amounted to one second. Of the million of fixed glittering points that adorn the sky, these are the only two whose distances have been calculated, and to express them, miles, leagues, or orbits seems inadequate. Light, whose speed is known to be 192,000 miles per second, would be three years in reaching our earth from the star of HENDERSON; and starting from BESSEL'S star and moving at the same rate it could only reach us in ten years. These are the nearest stars, but there are others whose distances are immeasurably greater, and whose light, though starting from them at the beginning of creation, may not have reached our globe! The stars visible to the eye are about 3,000, but the number increases with every increase of telescopic power, and may be said to be innumerable. They are not of uniform lustre or form, but vary in figure and brightness. Some of them have a _nebulous_ or cloudy appearance; and there are entire clusters with this dusky aspect, mostly pervaded, however, with luminous points of more brilliant hue. In the outer fields of astral space Sir WILLIAM HERSCHEL observed a multitude of nebulæ, one or two of which may be seen by the naked eye. All of them, when seen by instruments of low power, look like masses of luminous vapour; but some of them had brighter spots, suggesting to Sir WILLIAM the idea of a condensation of the nebulous matter round one or more centres. But when these luminous masses are examined by more powerful instruments many of them lose their cloudy form, and are resolved into shining points, "like spangles of diamond dust." It is in this way several nebulæ have yielded to the gigantic reflector of Lord ROSSE, and others with still greater optical resources may follow. This brings us to the first questionable and controversial portion of the _Vestiges_; namely,--the NEBULAR HYPOTHESIS. It is among the gaseous bodies just described, in the outer boundary of Nature, which neither telescope nor geometry can well reach, that speculation has laid its _venue_, and commenced its aerial castles. LAPLACE was the first to suggest the nebular hypothesis, which he did with great diffidence, not as a theory proved, or hardly likely, but as a mathematical possibility or illustration. His range of creation, moreover, was not so vast as that of our author, which assumes to compass the entire universe, but was limited to the evolution of the solar system. The mode in which this might be evolved, LAPLACE thus explains:-- He conjectures that in the original condition of the solar system the sun revolved upon his axis, surrounded by an atmosphere which, in virtue of an excessive heat, extended far beyond the orbits of all the planets, the planets as yet having no existence. The heat gradually diminished, and as the solar atmosphere contracted by cooling, the rapidity of its rotation increased by the laws of rotatory motion, and an exterior zone of vapour was detached from the rest, the central attraction being no longer able to overcome the increased centrifugal force. The zone of vapour might in some cases retain its form, as we still see in Saturn's ring; but more usually the ring of vapour would break into several masses, and these would generally coalesce into one mass, which would revolve about the sun. Such portions of the solar atmosphere abandoned successively at different distances, would form planets in the state of vapour. These masses of vapour, it appears from mechanical laws, would have each its rotatory motion, and as the cooling of the vapour still went on, would each produce a planet that might have satellites and rings formed from the planet, in the same manner as the planets were formed from the atmosphere of the sun. All the known motions of the solar system are consistent and reconcileable with this theory of LAPLACE, and upon it the author of the _Vestiges_ has enlarged and founded his wider scheme of physical creation. He supposes the void of nature to have been originally filled with a universal FIRE MIST (p. 30), out of which all the celestial orbs were made and put in motion. How this mist was put in activity, and resolved into the luminous and revolving bodies that we now see, and one of which we inhabit is the first urgent perplexity to surmount in the conjecture. It is manifest that if a mist filled the entire region of space, a mist it must for ever remain, unless acted upon by some cause adequate to give it new action and arrangement. No sun, no stars or planets could spontaneously emanate from an inert vapour any more than from nothing. To meet this, his first difficulty, the author supposes that there were certain _nuclei_, or centres of greater condensation, analogous to those still remarked in the nebulæ of the heavens, and that these nuclei, by their superior attractive force, consolidated into spheres the gaseous matter around them:-- "Of nebulous matter," says he, "in its original state we know too little to enable us to suggest _how nuclei should be established in it_. But supposing that from a _peculiarity_ in the constitution nuclei are formed, we know very well how, by the power of gravitation, the process of an aggregation of the neighbouring matter to these nuclei should proceed until masses more or less solid should be detached from the rest. It is a _well-known law in physics, that when fluid matter collects towards, or meets in a centre, it establishes a rotatory motion_. See minor results of this law in the whirlpool and the whirlwind--nay, on so humble a scale as the water sinking through the aperture of a funnel. It thus becomes certain, that when we arrive at the stage of a nebulous star we have a rotation on its axis commenced." Up to this, however, the author has proved nothing. The existence of the fire-mist and nuclei are assumptions only, and the way by which he tries to account for rotatory motion is clearly erroneous. The aggregation of matter round the nuclei by gravitation would have no such tendency; no more than a perfect balance would of itself have a tendency to move about its fulcrum, or a falling stone to deviate from its vertical course. Gravitation would indeed compress the particles of matter, but its tendency and entire action is towards the nucleus; it compresses them no more on one side of the line of their direction to the centre of force than on any other side; and hence no _lateral_ or _rotatory motion_ would ensue. Rotation, therefore, is yet unaccounted for; though the author says _it is a well-known law in physics_ that when fluid matter collects towards, or meets in a centre, it establishes a rotatory motion; and then for illustration refers to a whirlwind or whirlpool. No such effect would follow the conditions stated, and an entire ignorance is betrayed of the laws of mechanical philosophy. In the whirlpool and the whirlwind the gyration is caused by the fluid passing, not _to_ the centre, but _through_ it and away from it; in the whirlpool downwards through the place of exit, in the whirlwind upwards to where the vacuum has caused the rapid aggregation. LAPLACE was too able a mathematician to commit these elementary blunders; he did not assume to account for rotation by inapplicable laws, but took for granted that the sun revolved upon its axis, and thence communicated a corresponding motion to the bodies thrown from its surface. But our author has sought to advance beyond his teacher, and in this way has shown his ignorance of physics by an egregious mistake. At this point we might stop, without following the ulterior steps by which the solar system is made to evolve out of heated vapour. Having got rotation, though by an impossible process, the author falls into the illustration already given of the theory of LAPLACE. The rotation of each nucleus or sun round its axis produces centrifugal force; that force, by refrigeration, increases beyond the centripetal force of gravity; in consequence rings are formed and detached from the surface, whose unequal coherence of parts mostly causes them to break into separate masses or planets, partaking of the motion of the bodies from which they have been separated, and these primaries in their turn becoming centres of gravitation and centrifugal force, throw off their secondaries, or _moons_. In this way the solar system and other systems upon a similar plan of arrangement, it is conjectured, may have been formed. According to the author the generative process is still in progress, and new worlds are in course of being thrown off from new suns in the confines of creation. These nebulous stars on the outer bounds of space, of varying forms and brightness, are supposed to be the centres of new systems in different stages of development, like children of various ages and growth in a numerous family. This is the author's own illustration (p. 20), and after giving it he proceeds:-- "Precisely thus, seeing in our astral system many thousands of worlds in all stages of formation, from the most rudimental to that immediately preceding the present condition of those we deem perfect, it is unavoidable to conclude that all the perfect have gone through the various stages which we see in the rudimental. This leads us at once to the conclusion that the whole of our firmament was at one time a diffused mass of nebulous matter, extending through the space which it still occupies. So also, of _course_, must have been the other astral systems. Indeed, we must presume the whole to have been originally in one connected mass, the astral systems being only the first division into parts, and solar systems the second. "The first idea which all this impresses upon us is, that the formation of bodies in space is _still and at present in progress_. We live at a time when many have been formed, and many are still forming. Our own solar system is to be regarded as completed, supposing its perfection to consist in the formation of a series of planets, for there are mathematical reasons for concluding that Mercury is the nearest planet to the sun, which can, according to the laws of the system, exist. But there are other solar systems within our astral systems, which are as yet in a less advanced state, and even some quantities of nebulous matter which have scarcely begun to advance towards the stellar form. On the other hand, there are vast numbers of stars which have all the appearance of being fully formed systems, if we are to judge from the complete and definite appearance which they present to our vision through the telescope. We have no means of judging of the _seniority of systems; but it is reasonable to suppose that among the many, some are older than ours_. There is, indeed, one piece of evidence for the probability of the comparative youth of our system, altogether apart from human traditions and the geognostic appearances of the surface of our planet. This consists in a thin nebulous matter, which is diffused around the sun to nearly the orbit of Mercury, of a very oblately spheroidal shape. This matter, which sometimes appears to our naked eyes, at sunset, in the form of a cone projecting upwards in the line of the sun's path, and which bears the name of the Zodiacal Light, has been thought a residuum or last remnant of the concentrating matter of our system, and thus may be supposed to indicate the comparative recentness of the principal events of our cosmogony. _Supposing the surmise and inference_ to be correct, and they may be held as so far supported by more familiar evidence, we might with the more confidence speak of our system as not amongst the elder born of Heaven, but one whose various phenomena, physical and moral, as yet lay undeveloped, while myriads of others were fully fashioned, and in complete arrangement. Thus, in the sublime chronology to which we are directing our inquiries, we first find ourselves called upon to consider the globe which we inhabit as a child of the sun, elder than Venus and her younger brother Mercury, but posterior in date of birth to Mars, Jupiter, Saturn, and Uranus; next to regard our whole system as probably of recent formation in comparison with many of the stars of our firmament. We must, however, be on our guard against supposing the earth as a recent globe in our ordinary conceptions of time. From evidence afterwards to be adduced, it will be seen that it cannot be presumed to be less than many hundreds of centuries old. How much older Uranus may be, no one can tell, far less how much more aged may be many of the stars of our firmament, or the stars of other firmaments, than ours." All this is ingenious and fluently expressed. The author has an easy way of surmounting his difficulties by the use of such little auxiliary phrases, as "of course," "it may be surmised," "it is reasonable to suppose," and so on; which, though trifling in themselves, help him in their connecting inferences through many embarrassing perplexities. But his hypothesis is yet unproved; his fire-mist is only a conjecture; his nuclei, scattered like so many eggs in space out of which future suns and worlds are in process of incubation, is of the same description, and rotation, the first step in his process of creation, would not ensue under the conditions he has assigned. Without dwelling on these shortcomings, we shall terminate this portion of the author's inquiry with a few general strictures. First, on its inconsistency with what we know of the solar system; and, secondly, on its inadequacy to explain the facts of which we are cognizant on our own globe. In the first place, for the hypothesis to be applicable to our system, it is requisite that the primary and secondary bodies should revolve, both in their orbits and round their axes, in one direction, and nearly in one plane. Most of the bodies of the system observe these laws, their orbits are nearly circular, nearly in the plane of the original equator of the solar rotation, and in the direction of that rotation. But there are exceptions; the comets, which intersect the equatorial plane in every angle of direction form one, and the most distant of the planets forms another. The satellites of Uranus are retrograde. They move from east to west in orbits highly inclined to that of their primary, and on both accounts are exceptions to the order of the other secondary bodies. Our author is so perplexed by this inconsistency that he first doubts the fact, and next tries to explain it by alleging that "it may be owing to a _bouleversement_ of the primary." What is meant by the _bouleversement_ of a planet none of his critics seem to apprehend, nor do we. But that the moons of Uranus are contrariwise to those of the other planets, Sir JOHN HERSCHEL has indubitably established; so that the author at any rate upon this point has sustained a bouleversement. Our own moon forms a third exception to his theory. According to his system, this satellite is a slip or graft from our planet, and in constitution, it might be inferred, would partake of the elements of the parent. But the fact is otherwise. The moon has no atmosphere, no seas, or rivers, nor any water, and of course totally unfit for human inhabitants, or organic life of any kind. It must, then, have had a different origin, or be in some earlier stage of development than that through which our earth has passed. Leaving these exceptions, we may next inquire into the relevant purposes of the nebular hypothesis, supposing its assumptions acquiesced in. Like the fanciful theories of the ancient philosophers, it seems only to involve a profitless topic of controversy, without solving natural phenomena. It does not unravel the mystery of the beginning, brings us no nearer to the first creative force. Like a good chemist, previous to analysis, the author first throws all matter into a state of solution; but granting him his fire-mist and nuclei in the midst, how or whence came this condition and arrangement of nature? What was its pre-existing state? or, if that be answered, how or whence was that preceding state educed, for it, too, must have had one prior to it? So that the mind makes no advances by such inquiries, is lost in a maze that can have no end, because it has no beginning; and, like Noah's messenger, for want of a resting place, is compelled to return to the first starting point. Easier, and quite as satisfactory, it seems to believe, as we have been taught to believe, that the celestial spheres were at once perfect and entire, projected into space from the hands of the maker, than that they were elaborated out of luminous vapour by gravity and condensation. Hopeless inquiry is thus foreclosed, an inquisition that cannot be answered, silenced, and removed out of the pale of discussion. It is not from any attribute of the Deity being impugned that the hypothesis is objectionable. Design and intelligence in the creation are left paramount as before, and our impression of the skill exercised, and the means employed, only transferred to another part of the work. He who produced the primordial condition the author supposes, who filled space with such a mist, composed of such materials, subjected to such laws, such constitution, that sun, moon, and stars necessarily resulted from them, appears omnipotent as ever. But it does not advance inquiry, nor assist us in explaining the wonders we contemplate in our own globe. Suppose a planet formed by the author's process, what kind of a body would it be? Something, as Professor WHEWELL suggests, resembling a large meteoric stone. How after wards came this unformed mass to be like our earth, to be covered with motion and organization, with life and general felicity? What primitive cause stocked it with plants and animals, and produced all the surprising and subtle contrivances which we find in their structure, all the wide and profound mutual dependence which we trace in their economy? Is it possible to conceive, as the _Vestiges_ inculcate, that man, with his sentiment and intellect, his powers and passions, his will and conscience, were also produced as the ultimate result of vapourous condensation? One more conjecture of the author, in this division of his subject, we shall only notice. It is that "the formation of bodies in space _is still in progress_." What may be doing in the nebulæ, in the region scarcely within reach of telescopic vision, in what may be considered the yet uninclosed and commonable waste of the universe, is a subject, we suspect, of much obscurity, and respecting which no precise intelligence has been received; but limiting attention to the solar system, which is nearer home and more within cognizance, the work seems finished, perfect, and unchangeable, and, like the Great Architect, made to endure for ever. This was the conclusion of LAPLACE; he proved that the state of our system is _stable_; that is, the ellipsis the planets describe will always remain nearly circular, and the axis of revolution of the earth will never deviate much from its present position. He also gave a mathematical proof that this stability is not accidental, but the result of design, of an arrangement by which the planets all move in the same direction, in orbits of small eccentricity and slightly inclined to each other. Reasoning from analogy, as the author of the _Vestiges_ is prone to do--extending our views from our solar system to other systems--other suns and revolving planets--it is fair to conclude that they are not less perfect in arrangement--subject to like conditions of permanency, and alike exempt from mutation, decay, collision, or extinction. Descending from this high region, we accompany the author to his next and lower field--the EARTH AND ITS GEOLOGICAL HISTORY. Our globe is somewhat less than 8,000 miles in diameter; it is of a spheroidal form, the equatorial exceeding the polar axis in the proportion of 300 to 299, and which slight inequality, in consequence of its diurnal revolution, is necessary to preserve the land near the equator from inundation by the sea. The mean density or average weight of the earth is, in proportion to that of distilled water, as 5.66 to 1. So that its specific gravity is considerably less than that of tin, the lightest of the metals, but exceeds that of granite, which is three times heavier than water. Descending below the surface, the first sensation that strikes is the increase of temperature. This is so rapid, that for every one hundred feet of sinking we obtain an increase of more than one degree of Fahrenheit's thermometer. If there be no interruption to this law, and no reason exists to conclude there is, it is manifest that at the depth of a few miles we must reach an intensity of heat utterly unbearable. Hence it follows that by no improvements in machinery can mining operations be carried down to a great depth below the surface. The greatest depth yet penetrated does not exceed three thousand feet, and forms a very small advance towards the earth's centre, distant 4,000 miles. Geologists, however, without penetrating far into the earth, have found means for obtaining an insight for several miles into its interior structure, and armed with hammer, chisel, and climbing hook, they explore the beetling sea-cliff, traverse the deepest valleys, and scale the highest mountains, carefully examining their formation, disposition, and substance, and are thus enabled to obtain some knowledge of the earth's stomach, as it were, by scrutinising the deposits and eruptive ejectments on its surface. For example, we come to a mountain composed of a particular substance with strata or beds of other rock lying against its sloped sides; we, of course, infer that the substance of the mountain dips away under the strata that we see lying against it. Suppose that we walk away from the mountain across the turned-up edges of the stratified rocks, and that for many miles we continue to pass over other stratified rocks, all disposed in the same way, till we begin to cross the opposite edges of the same beds; after which we pass over these rocks all in reverse order, till we come to another extensive mountain composed of similar materials to the first, and shelving away under the strata in the same way; we should then infer that the stratified rocks occupied a basin formed by the rocks of these two mountains, and by calculating the thickness right through these strata could say to what depths the rock of the mountain extended below. In this way has the interior of the globe been examined, and its contents and arrangement, for several miles below the surface, ascertained. The result of such inspection we leave the author of the _Vestiges_ to describe:-- "It appears that the basis rock of the earth, as it may be called, is of hard texture, and crystalline in its constitution. Of this rock, granite may be said to be the type, though it runs into many varieties. Over this, except in the comparatively few places where it projects above the general level in mountains, other rocks are disposed in sheets or strata, with the appearance of having been deposited originally from water. But these last rocks have nowhere been allowed to rest in their original arrangement. Uneasy movements from below have broken them up in great inclined masses, while in many cases there has been projected through the rents rocky matter more or less resembling the great inferior crystalline mass. This rocky matter must have been in a state of fusion from heat at the time of its projection, for it is often found to have run into and filled up lateral chinks in these rents. There are even instances where it has been rent again, and a newer melted matter of the same character sent through the opening. Finally, in the crust as thus arranged, there are, in many places, chinks containing veins of metal. Thus, there is first a great inferior mass, composed of crystalline rock, and probably resting immediately on the fused and expanded matter of the interior: next, layers or strata of aqueous origin; next, irregular masses of melted inferior rock that have been sent up volcanically and confusedly at various times amongst the aqueous rocks, breaking up these into masses, and tossing them out of their original levels." This, we believe, is a correct outline of the crust of the earth, so far as it has been possible to observe it. It exhibits extraordinary signs of commotion and vicissitude; the lowest rocks indicating a previous condition of igneous fusion; those above them of aqueous solution. Fire and water have thus been the chief tellurian anarchists, and the shaking of continents and the constant shifting of level in sea and land still continue to attest their restless energies. That igneous matter has, during many periods, been protruded from below--that mountains have risen in succession from the sea, and injected their molten substance through cracks and fissures of superincumbent strata--are facts resting on indubitable evidence. Many masses of granite became the solid bottom of some portions of the sea before the secondary strata were laid gradually upon them. The granite of Mont Blanc rose during a recent tertiary period. "We can prove," says Professor SEDGWICK, "more than mere shiftings of level, and that many portions of sea and land have entirely changed their places. The rocks at the top of Snowdon are full of petrified sea-shells; the same may be said of some high crests of the Alps, Pyrenees, and Andes. We have proof demonstrative that many parts of Scotland, and that all England, formed, during many ages, the solid bottom of the sea. It may be true that the antagonist powers of nature during the human period have reached a kind of balance. But during all geological periods there have been such long intervals of repose, or of such gradual movements, that we may trace the history of the earth in the successive deposits formed in the waters of the sea." This is the great business of geology. Although at first sight the interior of the earth appears a confused scene, after careful observation we readily detect in it a regularity and order from which much instructive light is thrown on its past vicissitudes. The deposition of the aqueous rocks and the projection of the volcanic have unquestionably taken place since the settlement of the earth in its present form. They are, indeed, of an order of events which are going on under the agency of intelligible causes, down to the present day. We may therefore consider these generally as recent transactions. But advancing to the far distant antecedent era of its existence, we may consider it to have been a globe of its present size enveloped in the crystalline rock already described, with the waters of the present seas and the present atmosphere around it, though these were probably in considerably different conditions, both as to temperature and their constituent materials, from what they now are. We may thus presume that, without this primitive case of granitic texture, the great bulk of the matters of our earth were agglomerated, whether in a fluid or solid state is uncertain; but there cannot be any doubt that they continue to exist in a condition of great heat and compression, having a mean density of more than double that of the minerals on the surface. Judging from the results and still observable conditions, it may be inferred that the heat retained in the interior of the globe was more intense, or had greater freedom to act, in some places than in others. These become the scenes of volcanic operations, and in time marked their situations by the extrusion from below of trap and basalts--rocks composed of the crystalline matter, fused by intense heat, and developed on the surface in various conditions, according to the particular circumstances under which it was sent up; some, for example, being thrown up under water, and some in the open air, which contingencies would make considerable difference in its texture and appearance. It would, however, be a mistake to infer that, previous to these eruptions, the earth was a smooth ball, with air and water playing round it. Geology tells us plainly that there were great irregularities--lofty mountains, interspersed with deep seas--and by which, perhaps, the mountains were wholly or partially covered. But it is a fact worthy of observation that the solids of our globe cannot for a moment be exposed to water or the atmosphere without becoming liable to change. They instantly begin to wear down. The matter so worn off being carried into the neighbouring depths and there deposited, became the components of the successive series of stratified rocks, extending from the basal envelope of granite to the earth's surface, and which it will be proper briefly to describe. DEPOSITS OR ROCK FORMATIONS. The first of the series is the _Gneis and Mica Slate System_, of which examples are exposed to view in the Highlands of Scotland and the west of England. These earliest stratified rocks contain no matters which are not to be found in the primitive granite. They are the same in material--silica, mica, quartz, or hornblende--but changed into new forms and combinations, and hence called by Mr. LYELL metamorphic rocks. Some of them are composed exclusively of one of the materials of granite; the _mica schist_, for example, of mica; the _quartz rocks_, of quartz. In the metamorphic rocks no organic remains have been found, and they are geologically below all the rocks that do contain traces of animal life. From the primary rocks we pass into the next ascending series, called the _Clay Slate and Grauwacke Slate System_, which in some places is found resting immediately on the granite, the antecedent bed being there wanting. This deposit has been well examined, because some of its slate beds have been extensively quarried for domestic purposes. By some geologists it is called the _Silurian System_, it being largely developed at the surface of a district of western England formerly occupied by the Silures. It is found also in North Wales and in the north of England, in beds of great thickness, and in Scotland, but there the Silurian rocks are more feebly represented. The _Old Red Sandstone, or Devonian System_, comes next. It forms the material of the grand and rugged mountains which fringe many parts of our Highland coasts, and ranges, on the south flank of the Grampians, from the eastern to the western sea of Scotland. There is no part of geology and science more clear than that which refers to the ages of mountains. It is as certain that the Grampian mountains are older than the Alps and Apennines, as it is that civilisation had reached Italy and enabled her to subdue the world, while Scotland was the abode of barbarism. The Pyrenees, Carpathians, and other ranges of continental Europe are all younger than these Scotch hills, or even the insignificant Mendip Hills of southern England. Stratification tells this tale as plainly, and more truly, than LIVY tells the story of the Roman republic. It tells us that at the time when the Grampians sent streams and detritus to straits where now the valleys of the Forth and Clyde meet, the greater part of Europe was a wide ocean. The last three series of strata contain the remains of the earliest occupants of the globe, and of which we shall soon speak. They are of enormous thickness--in England, not much less than 30,000 feet, or nearly six miles. We have now arrived at the secondary rocks, of which the lowest group is the _Carboniferous Formation_, so called from its remarkable feature of numerous interspersed beds of coal. It commences with beds of the mountain limestone, which in England attains a depth of 800 yards. Coal is altogether composed of the matter of a terrestrial vegetation, transmuted by putrefaction of a peculiar kind beneath the surface of water, and in the absence of air. From examples seen at the present day at the mouths of such rivers as the Mississippi, which traverse extensive sylvan regions, it is thought that the vegetation, the rubbish of decayed forests, was carried by rivers into estuaries, and there accumulated into vast natural rafts, until it sank to the bottom, where an overlayer of sand or mud would prepare it for becoming a stratum of coal. Others conceive that the vegetation first went into the condition of peat moss, that a sink in a level then exposed it to be overrun by the sea and covered with a layer of sand or mud; that a subsequent uprise made the mud dry land, and fitted it to bear a new forest, which afterwards, like its predecessors, became a bed of peat--that, in short, by repetitions of this process the alternate layers of coal, sand and shell constituting the carboniferous group were formed. The _Magnesian Limestone_ deposits succeed the carboniferous, and sometimes pass into them by insensible gradations. In the south of England they are represented by conglomerates, and partly composed of the solid and more or less rounded fragments of the older strata. They afford a proof of what geologists have often occasion to remark of the long periods of time during which the ancient works of nature were perfected; for the older rocks were solid as they are now, and their organic remains petrified at the time these conglomerates were forming. We can only briefly glance at the remaining chapters of geological history. The _New Red Sandstone_ forms the base of the great central plains of England, and is surmounted by the oliferous marls and red arenaceous beds which pass under the succession of great oolitic terraces that stretch across England from the coasts of Dorsetshire to the north-eastern coast of Yorkshire. It marks the commencement of an important era, being the strata in which land animals are first found. The _Oolte System_ which follows marks the beginning of mammalia, and in some of its beds in Buckinghamshire are found the exuviæ of tropical trees. Near Weymouth, in the well-known dirt beds, are found trees with their silicified trunks growing up in the position of nature, and their roots embedded in the soil on which they grew. Next we have the chalk or _Cretaceous Formation_, that makes such a conspicuous figure in England. The celebrated cliffs of Dover are of this era. It forms a stripe from Yorkshire to Kent, and is found in France, Germany, Russia, and in North America. The English chalk beds are 1,200 feet thick, showing the considerable depth of the ocean in which they were formed. Their origin has been a questionable topic; they were thought to be formed from the detritus of coral reefs, but Professor EHRENBERG has recently announced, as the result of his microscopical researches, that chalk is composed partly of inorganic particles and partly of shells of inconceivable minuteness, a cubic inch of the substance containing about ten millions of them. In the hollows of the chalk-beds have been formed series of strata--clay, limestone, marl alternating--to which the name of the _Tertiary System_ has been given. It is irregularly distributed over vast surfaces of all our continents, and must be considered as the beds of estuaries left at the conclusion of the cretaceous period. London and Paris rest on basins of this formation, and another such basin extends from near Winchester under Southampton, and reappears in the Isle of Wight. We hasten upward to the _Diluvial System_, which brings us near to the present surface. To this era is referred the erratic blocks, or gigantic boulder stones, which have been driven by floods across our continents, or drifted in icebergs over valleys, and perched sometimes on mountain tops. To it also must be referred the _till_ of Scotland and the great brown clay of England, and our vast beds of gravel and superficial rubbish, connected with the deluvium in the history of _ossiferous caverns_, of which that examined by Dr. BUCKLAND at Kirkdale is an example. They occur in the calcareous strata, as the great caverns generally do, and have in all instances been naturally closed up till the period of their discovery. At Kirkdale the remains of twenty-four species of animals were found--namely, pigeon, lark, raven, duck, partridge, mouse, water-rat, rabbit, hare, hippopotamus, rhinoceros, elephant, weasel, fox, wolf, deer, ox, horse, bear, tiger, hyena. From many of the bones of the gentler of these animals being found in a broken state, it is supposed that the cave was the haunt of hyenas and other predaceous animals, by which the smaller ones had been consumed. We come last to the _Modern_ or _Superficial Formation_, of which the best specimen is the great Bedford level, that spreads over the lower lands of Norfolk, Cambridgeshire, and Lincolnshire, consisting of accumulations of silt, drifted matter, and bog-earth, some of which began before the earliest periods of British history. When these accumulations are removed by artificial means, we find below sometimes shells of recent species, and the remains of an old estuary, sometimes sand-banks, gravel beds, stumps of trees, and masses of drifted wood. On this recent surface are found skulls of a living species of European bear, skeletons of the Arctic wolf, European beaver and wild boar, and numerous horns and bones of the roebuck and red deer, and of the gigantic stag or Irish elk. They testify to a zoology on the verge of that now prevailing or melting into it. In corresponding deposits of North America are found remains of the mammoth, mastadon, buffalo, and other animals of extinct or living species. Considering it best not to interrupt the description of the successive formations, this is almost the only allusion that has been made to the fossils which constitute so important a part of geological science. It is now to be explained that from an early period, that is, from the metamorphic deposit to the close of the rock series, each formation is found to enclose remains of the organic beings, plants, and animals, which flourished upon earth during the time they were forming; and these organisms, or such parts of them as were of sufficient solidity, have been in many instances preserved with the utmost fidelity, although for the most part converted into the substance of the enclosing mineral. The rocks may be thus said to form a kind of history of the organic departments of nature apparently from near their beginning to the present time. It is upon the commencement and progress of life under these circumstances that the author of the _Vestiges of Creation_ has put forth some of his most startling and controversial propositions; but before noticing them it will be useful to prepare the way by shortly describing the gradations of organic existences, following the same order as observed in the rock series, by beginning with the lowest or humblest forms of organization. RISE AND PROGRESS OF PLANTS AND ANIMALS. The interior of the earth reveals wonders not less impressive than those of the skies. We have seen in the last section how the crust of our globe is composed of successive layers or tiers of strata, rising upward, terrace upon terrace, till we reach the present vegetable mould or superficial platform of animated existence. In the aggregate these formations or systems, marking the several epochs in nature's development, may extend to a depth, as Dr. BUCKLAND conjectures, of ten or fifteen miles below the surface, and each may be considered a vast cemetery or graveyard, entombing the remains of ages long anterior to human creation. We, in fact, live upon a pile of worlds, and anticipating the future from past records and from changes still manifest from the shallowing soundings of neighbouring seas, it is not improbable that the existing scene of bustle may have heaped upon it as many superincumbent masses as the lowest of the rocks enclosing the vestiges of life. If not with a kind of awe, it must have certainly been with intense curiosity that the first investigators of fossilology looked upon the earliest forms of animated being of which we have any traces as existing upon this globe. These first denizens, however, seem to have been of a simple structure and humble order, not fit to play high class characters. No land animals are found among them, none which could breathe the atmosphere, none but tenants of the water, and even animals so high in the scale as fish were wanting. In popular language, the earliest fossils are corals and shellfish. But to make the subject generally intelligible it will be necessary first to define the orders of the animal kingdom. CUVIER was the first to give a philosophical view of the animal world in reference to the plan on which each animal is constructed. According to him there are four forms on which animals have been modelled, and of which ulterior divisions are only slight modifications founded on the development or addition of some parts that do not produce any essential change of structure. The four great branches of the animal world are the _vertebrata_, _mollusca_, _articulata_, and _radiata_. The _vertebrata_ are those animals which (as man and other sucklers, birds and fishes) have a backbone and a skull with lateral appendages, within which the viscera are excluded, and to which the muscles are attached. The _mollusca_ or soft animals have no bony skeleton; the muscles are attached to the skin, which often include stony plates called shells; such mollusca are shell-fish, others are cuttle-fish, and many pulpy sea animals. The _articulata_ consist of crustacea (lobsters, &c.), insects, spiders, and annulos worms, which, like the other classes of this branch, consist of a head and a number of successive portions of the body jointed together, whence the name. Finally the _radiata_ include the animals known under the name of zoophytes. Now it is fossils of the _radiata_ division of the animal kingdom that are found in the lowest stratified rocks, polypiaria and crinodia, the first including various forms of these extraordinary animals (corallines) which still abound in tropical seas, often obstructing the course of the mariner, and even laying the foundation of new continents. The crinoids are an early and simple form of the large family of star-fishes; the animal is little more than a stomach, surrounded by tentacula to provide itself with food, and mounted upon a many-jointed stalk, so as to resemble a flower upon its stem. Along with these in the slate system are a few lowly genera of crustacea, and of a higher class, the mollusca, and the existence of these imply the contemporary existence of certain humbler forms of life, vegetable and animal, for their subsistence, forming a scene approaching to what is found in seas of the present day, excepting that fishes, nor any higher vertebrata, as yet roamed the marine wilds. The animal species of this era seem to have been few in number, and almost the whole had become extinct before the next group of strata had been formed. In the Silurian deposit the vestiges of life become more abundant, the number of species extended, and important additions made in the traces of sea plants and fishes. Remains of fishes have been detected in rocks immediately over the Aymestry limestone, being apparently the first examples of vertebrated animals which breathed upon our planet. (p. 64). The cephaloda, represented in our era by the nautilus and cuttle-fish, pertain to the Silurian formation, and are the most highly organised of the mollusca, possessing in some families an internal bony skeleton, together with a heart and a head with mandibles not unlike those of the parrot. In the Old Red Sandstone the same marine specimens are continued with numerous additions. Several of the strata are crowded with remains of fish, showing that the seas in which these beds were deposited had swarmed with that class of inhabitants. The predominating kinds are of an inferior model to the two orders which afterwards came into existence, and still are the principal fishes of our seas; the former are covered with integuments of a considerably different character from the true scales covering the latter, and which orders, from their form of organization, are named stenoid and cycloid. Up to the present we find proofs of the general uniformity of organic life over the surface of the earth at the time when each particular system of rocks was formed. The types of being formed in the old red as in preceding deposits, are identical in species with the remains that occur in the corresponding class of rocks in Brittany, the Hartz, Norway, Russia, and North America; attesting the similarity and almost universality, if not contemporary character, of terrestrial changes. A few other geological facts may be here mentioned for recollection, and which throw light on the marine animal and vegetable forms of this and preceding eras. First there was comparatively an absence of salt in the early ocean; and next the temperature of the earth is conjectured to have been higher, and perhaps almost uniform throughout. The higher temperature of the primeval times is attributed to the greater proximity or intensity of the globe's internal heat, and which, poured through cracks and fissures of the lately concreted crust, M. BRONGNIART supposes to have been sufficiently great to overpower the ordinary meteorological influences and spread a tropical climate all over its surface. It must be further borne in mind that as yet no _land animals or plants_ existed, and for this presumable reason, that dry land had not appeared. It is only in the next or carboniferous formation that evidence is traced of island or continent. As a consequence of this emergence there was fresh water; for rain, instead of returning to the sea, as formerly, was collected in channels of the earth and became springs, rivers, and lakes. It was made a receptacle for an advance in organism, and land plants became a conspicuous part of the new creation. According to the _Vestiges of Creation_, terrestrial botany began with classes of comparatively simple forms and structure. In the ranks of the vegetable kingdom the lowest place is taken by plants of cellular tissue, and which have no flowers, as lichens, mosses, fungi, ferns, and sea-weeds. Above these stand plants with vascular tissue, bearing flowers, and of which there are two subdivisions: first, plants having one seed-lobe, and in which the new matter is added within, of which the cane and palm are examples; second, plants having two seed lobes, and in which the new matter is added on the outside under the bark, of which the pine, elm, oak, and all the British forest trees are examples. Now the author of the _Vestiges_ states that two-thirds of the plants of this era belong to the cellular kind, but to this one of his ablest critics (_Edinburgh Review_ for July) demurs, asserting that the carboniferous epoch shows a gorgeous _flora_--that the first fruits of vegetable nature were not rude, ill-fashioned forms, but in magnificence and complexity of structure equal to any living types, and that the forest approached the rank and complicated display of a tropical jungle, where the prevalence of great heat with great moisture, combined with the fact that the atmosphere contained a greater proportion of the natural food of plants, must undoubtedly have forcibly stimulated vegetation, and in quantity and luxuriance of growth, if not fineness of organization, produced it in rich abundance. The earth, it is likely, was one vast forest, which would perform a most important part for the good of its future inhabitants, helping to purge the air of its excess of carbonic acid, by which the earth's surface would be prepared for its new occupants. The animal remains of this era are not numerous in comparison with those that go before or follow. Contrary to what the author of the _Vestiges_ supposes (p. 111), insects were already buzzing in the air; there were, however, no crawling reptiles on the ground, and it is a doubtful point whether birds cheered the ancient forests with their song. But fishes reached their most perfect organic type. They were the lords of creation, and had a structure in conformity with their high office. Since then the class has increased in its species, but has degenerated to a less noble type. In the next formation, the New Red Sandstone, reptiles make their appearance. They are considered next to fishes in the zoological scale. So nearly are they sometimes connected, that it is doubtful to which class they belong. Many reptiles are also amphibious, adapted either to water or land. The surface of the globe abounded in large flat, muddy shores, and was suited to the new order of visitants called into existence. In the Oolite System, mostly consisting of calcareous beds, mammals make their appearance. Some additions were made to the reptile form. One animal (the behemite) appeared, but terminated in the next era. In the following series of rocks mammals increase in abundance. The advance in land animals is less marked, but considerable in the tertiary strata. The tapir forms a conspicuous type. One animal of the kind was eighteen feet long, and had a couple of tusks turning down from the lower jaw, by which it could attach itself, like the walrus, to a bank, while its body floated in the water. Many animals of a former period disappear, and are replaced by others belonging to still existent families--elephant, hippopotamus, and rhinoceros--though extinct as species. Some of these forms are startling from their size. The great mastadon was a species of elephant living on aquatic plants, and reaching the height of twelve feet. The mammoth was another elephant, and supposed to have survived till comparatively recent times. The megatherium is an incongruity of nature, of gigantic proportions, yet ranking in a much humbler order than the elephant, that of the edenta, to which the sloth, ant-eater, and armadilla belong. The megatherium had a skeleton of enormous solidity, with an armour-clad body, and five toes, terminating in huge claws to grasp the branches on which it fed. Finally, beside the dog, cat, squirrel, and bear, we have offered to us, for the first time, oxen, deer, camel, and other specimens of the rumantia. Traces of the quadrumane, or monkey, have been found in the older tertiaries of France, India, and England. So that we may now be said to have arrived at the zoological forms not long antecedent to the appearance of the chief of all, bimana, or man, and shall here pause to consider the conclusions of the author of the _Vestiges of Creation_ on the origin of the organic existences that have been successively exhibited. It will be convenient, however, first to introduce a synoptic view of the evolutions of the earth as set forth in this and the preceding section. For this purpose the author has introduced a parallel table, exhibiting on one side a scale of animal life beginning with the humblest and ascending to the highest species; and on the other side the successive series of rock formations, in which their fossiliferous remains have been found up to the present superficial deposits of the globe. Objections have been made to the correctness of the author's analogies, scale, and his classification of animals, the chief of which will be adverted to in the next section; but the table is essential, as presenting at one view an outline of the hypothesis he has sought to establish. SCALE OF ANIMAL KINGDOM. ORDER OF ANIMALS IN ASCENDING SERIES FOETAL HUMAN BRAIN OF ROCKS. RESEMBLES, IN _Invertebrata._ 1 Infusoria _Traces of Infusoria_(?) 1 Gneiss and Mica\ Slate System \ 2 Polypi Polypiaria \ \ 5 Echinodermata Echinodermata \ \ { 7 Brachiopoda {15-20 Brachiopoda} Crustacea } 2 Clay Slate System \ 1st month, typically, Moll-{ 9 Pteropoda Artic-{Crustacea Pteropoda } / } that of an usca {10 Gasteropoda ulata {12-14 Gasteropoda} Annelides / / avertebrated animal {11 Cephalopoda {Annelides Cephalopoda} \ / } 3 Silurian system / _Vertebrata._ { _Remains of Fishes_ / / { Fishes of low type; \ \ 32-36 Fishes { heterocercal; allied } 4 Old Red Sandstone } 2nd month, that of a fish; { to crustacea / / { Sauroid Fishes \ 37 Batrachia (frogs, &c.) Batrachia \ } 5 Carboniferous 39 Sauria (lizards, &c.) Sauria / formation 40 Chelonia (tortoises) Chelonia / 3rd month, that of a turtle; 41-46 Birds _Footsteps of Birds_ 6 New Red Sandstone 4th month, that of a bird; 47 Cetacea (dolphins, whales, &c.) _Bones of a \ Cetaceous Animal_ } 7 Oolite _Bones of a Marsupial_ / 8 Chalk 48 Pachydermata (tapirs, &c.) Pachydermata \ 49 Edentata (sloths) Edentata \ 50 Rodentia (squirrels, hare, &c.) Rodentia \ 5th month, that of a rodent; 51 Marsupialia (opossums, &c.) Marsupialia \ 52 Ruminantia (oxen, stag, &c.) Ruminantia \ 6th month, that of a ruminant; 53 Amphibia (seals) } 9 Tertiary 54 Digitigrada (dog, cat, &c.) Digitigrada / 7th month, that of a digitigrade animal; 55 Plantigrada (bear, &c.) Plantigrada / 56 Insectivora (shrew, &c.) Insectivora / 57 Cheiroptera (bats) Cheiroptera / 58 Quadrumana (apes) Quadrumana / 8th month, that of the quadrumana; 29 Bimana (man) Bimana 10 Superficial deposits 9th month, attains full human character. TRANSMUTATION OF SPECIES. In the two last sections we have gone through the earth's geological history, first of the changes in its physical structure, next of the mutations in the organic forms that have, in serial order, appeared in the successive strata of its external envelope, from the period of that far distant crisis when it was a molten globe on which its primitive granitic covering was just beginning to concrete, in consequence of abating heat, until we have arrived at the first prognostic signs of approaching human existence. The rock upon rock of vast thickness, by which the earth's crust, through countless ages, has been formed, unquestionably constitutes a most extraordinary phenomenon of physical creation, but hardly so marvellous and incomprehensible as the beginning, progress, and end of the divers orders of marine and terrestrial beings that filled each world of life. It is to geologists, to PLAYFAIR, HUTTON, LYELL, BUCKLAND, SEDGWICK, OWEN, and other great names, native and foreign, to whom we are indebted for this singular revelation of Nature's works. It is their unwearied research that has opened to us the surprising spectacle we have attempted briefly to describe of the diversified groups of species which have, in the course of the earth's history, succeeded each other at vast intervals of time; one set of animals and plants wholly or partly disappearing from the face of our planet, and others, which apparently did not before exist, becoming the only or predominant occupants of the globe. Now the great question arises--whence, by what power, or by what law, were these reiterated transitions brought about? Were the organized species of one geological epoch, by some long-continued agency of natural causes, transmuted into other and succeeding species? or were there an extinction of species, and a replacement of them by others, through special and miraculous acts of creation? or, lastly, did species gradually degenerate and die out from the influence of the altered and unfavourable physical conditions in which they were placed, and be supplanted by immigrants of different species, and to which the new conditions were more congenial? The last, we confess, is the view to which we are most inclined--first, because we think a transmutation of species, from a lower to a higher type, has not been satisfactorily proved; and second, because of the strong impression we entertain, that the universe, subject to certain cyclical and determinate mutations, was made complete at first, with self-subsisting provisions for its perpetual renewal and conservation. We shall advert to this matter hereafter; but at present it is the conclusions of the author of the _Vestiges_ that claim consideration. He adopts the first interpretation of animal phenomena, namely, that there has been a transmutation of species, that the scale of creation has been gradually advancing in virtue of an inherent and organic law of development. Nature, he contends, began humbly; her first works were of simple form, which were gradually meliorated by circumstances favourable to improvement, and that everywhere animals and plants exhibit traces of a parallel advance of the physical conditions and the organic structure. The general principle, he inculcates, is, that each animal of a higher kind, in the progress of its embryo state, passes through states which are the final condition of the lower kind; that the higher kinds of animals came later, and were developed from the lower kinds, which came earlier in the series of rock formations, by new peculiar conditions operating upon the embryo, and carrying it to a higher stage. These conclusions the author maintains geology has established, and of the results thence derived he gives the subjoined recapitulation:-- "In pursuing the progress of the development of both plants and animals upon the globe, we have seen an advance in both cases, from simple to higher forms of organization. In the botanical department we have first sea, afterwards land plants; and amongst these the simpler (cellular and cryptogamic) before the more complex. In the department of zoology, we see, first, traces all but certain of infusoria [shelled animalculæ]; then polypiaria, crinoidea, and some humble forms of the articulata and mollusca; afterwards higher forms of the mollusca; and it appears that these existed for ages before there were any higher types of being. The first step forward gives fishes, the humblest class of the vertebrata; and, moreover, the earliest fishes partake of the character of the lower sub-kingdom, the articulata. Afterwards come land animals, of which the first are reptiles, universally allowed to be the type next in advance from fishes, and to be connected with these by the links of an insensible gradation. From reptiles we advance to birds, and thence to mammalia, which are commenced by marsupialia, acknowledgedly low forms in their class. That there is thus a progress of some kind, the most superficial glance at the geological history is sufficient to convince us." Now this appears plausible and conclusive, but the correctness of the recapitulation here made, and its conformity to actual nature, have been sharply disputed. It may be true that sea plants came first, but of this there is no proof; and of land plants there is not a shadow of evidence that the simpler forms came into being before the more complex: the simple and complex forms are found together in the more ancient _flora_. It is true that we first see polypiaria, crinoidea, articulata, and mollusca, but not exactly in the order stated by the author. It is true that the next step gives us fishes, but it is not true that the earliest fishes link on to the lower sub-kingdom, the articulata. It is true that we afterwards find reptiles, but those which first appear belong to the highest order of the class, and show no links of an insensible gradation into fishes. In the tertiary deposit of the London clay the evidence of concatenation entirely fails. Among the millions of organic forms, from corals up to mammalia of the London and Paris basins, hardly a single secondary species is found. In the south of France it is said that two or three secondary species struggle into the tertiary strata; but they form a rare and evanescent exception to the general rule. Organic nature at this stage seems formed on a new pattern--plants as well as animals are changed. It might seem as if we had been transported to a new planet; for neither in the arrangement of the genera and the species, nor in their affinities with the types of a pre-existing world, is there any approach to a connected chain of organic development. For some discrepancies the author endeavours to account, and it is fair to give his explanation:-- "Fossil history has no doubt still some obscure passages; and these have been partially adverted to. Fuci, the earliest vegetable fossils as yet detected, are not, it has been remarked, the lowest forms of aquatic vegetation; neither are the plants of the coal-measures the very lowest, though they are a low form, of land vegetation. There is here in reality no difficulty of the least importance. The humblest forms of marine and land vegetation are of a consistence to forbid all expectation of their being preserved in rocks. Had we possessed, contemporaneously with the fuci of the Silurians, or the ferns of the carboniferous formation, fossils of higher forms respectively, _equally unsubstantial_, but which had survived all contingencies, then the absence of mean forms of similar consistency might have been a stumbling-block in our course; but no such phenomena are presented. The blanks in the series are therefore no more than blanks; and when a candid mind further considers that the botanical fossils actually present are all in the order of their organic development, the whole phenomena appear exactly what might have been anticipated. It is also remarked, in objection, that the mollusca and articulata appear in the same group of rocks (the slate system) with polypiaria, crinoidea, and other specimens of the humblest sub-kingdom; some of the mollusca, moreover, being cephalopods, which are the highest of their division in point of organization. Perhaps, in strict fact, the cephalopoda do not appear till a later time, that of the Silurian rocks. But even though the cephalopoda could be shewn as pervading all the lowest fossiliferous strata, what more would the fact denote than that, in the first seas capable of sustaining any kind of animal life, the creative energy advanced it, in the space of one formation, (no one can say how long a time this might be,) to the highest forms possible in that element, excepting such as were of vertebrate structure. It may here be inquired if geologists are entitled to set so high a value as they do upon the point in the scale of organic life which is marked by the upper forms of the mollusca. It will afterwards be seen that this is a low point compared with the whole scale, if we are to take as a criterion that parity of development which has been observed in the embryo of one of the higher animals. _The human embryo passes through the whole space representing the invertebrate animals in the first month, a mere fraction of its course._ There is indeed a remarkably rapid change of forms in such an embryo at first: the rapidity, says Professor Owen, is 'in proportion to the proximity of the ovum to the commencement of its development;' and, conformable to this fact, we find the same zoologist stating that, in the lowest division of the animal kingdom, (the Acrita of his arrangement,) there is a much quicker advance of forms towards the next above it, than is to be seen in subsequent departments. There is, indeed, to the most ordinary observation, a rapidity and force in the productive powers of the lowest animals, which might well suggest an explanation of that rush of life which seems to be indicated in the slate and Silurian rocks. With regard to the so-called early occurrence of fishes partaking of the saurian character, I would say that their occurrence a full formation after the earliest and simplest fishes, is, considering how little we know of the space of time represented by a formation, not early: their being later in any degree is the fact mainly important. The subsequent rise of new orders of fishes, fully piscine in character, may be explained by the supposition of their having been developed, as is most likely, from a different portion of the inferior sub-kingdom. In short, all the objections which have been made to the great fact of a general progress of organic development throughout the geological ages, will be found, on close examination, to refer merely to doubtful appearances of small moment, which vanish into nothing when rightly understood." Upon some of the chief points here involved, it may be remarked that the most eminent physiologists are not agreed; they are not agreed that animals can be arranged in a series, passing from lower to higher; nor that animals of a higher kind in the embryo state pass through the successive stages of the lower kinds; the character of these stages, in the asserted doctrine, being taken from the brain and heart, and man being the highest point of the series. There are physiologists too who deny that the brain of the human embryo at any period, however early, resembles the brain of any mollusk or of any articulata. It never, they assert, passes through a stage comparable or analogous to a permanent condition of the same organ in any invertebrate animal; and in like manner the spinal cord in the human vertebræ at no period agrees with the corresponding part of the lower kind of animals. The moment it becomes visible in the human embryo, it is entirely dorsal in position; while in mollusks and articulatas a great part, or nearly the whole, is ventral. The same is true of the heart, or centre of the vascular system, which has always a different relative position in the great nervous centre in the human embryo from what it has in any articulate animal, and in most mollusks. A second position in the _Vestiges_ appears not to have been established--namely, as to the uniform geological arrangement of different organic structures. It is not true that _only_ the lowest forms of animal life are found in the lowest fossiliferous rocks, and that the more complicated structures are gradually and exclusively developed among the higher bands in what might be called a natural ascending scale. On the contrary, the predaceous cephalopods and the highly organized crustaceous are among the oldest fossils. Such appears to be the order of nature as evidenced by facts, and it must be admitted, however repugnant to preconceived notions or mere mortal conjectural amendments. In the third place the evidence seems to preponderate in favour of _permanency of species_. There can be no doubt that both plants and animals may, by the influence of breeding, and of external agents operating upon their constitution, be greatly modified, so as to give rise to varieties and races different from what before existed. But there are limits to such modifications, as in the different kind and breed of dogs; and no organized beings can, by the mere working of natural causes, be made to pass from the type of one species to that of another. A wolf by domestication, for example, can never become a dog, nor the ourang-outang by the force of external circumstances be brought within the circle of the human species. In this opinion Mr. LYELL, Dr. PRICHARD, and Mr. LAWRENCE, concur. The general conclusion at which they have arrived is, that there is a capacity in all species to accommodate themselves to a certain extent to a change of external circumstances; this extent varying greatly according to the species. There may thus be changes of appearance or structure, and some of these changes are transmissible to the offspring; but the mutations thus superinduced are governed by certain laws, and confined within certain limits. Indefinite divergence from the original type is not possible, and the extreme limit of possible variation may usually be reached in a short period of time; in short, Professor WHEWELL concludes (_Indications of Creation_, p. 56), _that every species has a real existence in nature_, and a transmutation from one to another does not exist. Thus for example, CUVIER remarks that, notwithstanding all the differences of age, appearance and habits, which we find in the dogs of various races and countries, and though we have (in the Egyptian mummies) skeletons of this animal as it existed 3,000 years ago, the relation of the bones to each other remains essentially the same; and with all the varieties of their shape and size, there are characters which resist all the influences, both of external nature, of human intercourse, and of time. What varieties, again, in the forms of the different breeds of horses and horned cattle; racers, hunters, coach horses, dray horses, and ponies; short-horns and long-horns, Devons and Herefords, polled galloways and Shetlands; how unlike are the unimproved breeds of cattle as they existed a century ago before the march of agricultural improvement began, and how different were most of these as then existing in what may be called the normal state from the wild cattle produced in Chillington Park. It has been found, however, when external and artificial conditions are removed, and these different breeds are allowed to run wild, as in the Pampas and Australia, no matter what the diversity of size, shape, and colour of the domestic breeds, they reverted in their wild state, in these respects, to their primitive types. So again with regard to cultivated vegetables and flowers. How different are the species of the red cabbage and the cauliflower; who would have expected them to be varieties of the wild _brassica oleracea_? Yet from that they have been derived by cultivation. They have, however, a tendency like animals to revert to the original type, or, in the gardener's phrase, to degenerate, which it requires the utmost care on his part to counteract. When left to a state of nature, they speedily lose their acquired forms, properties and character, and regain those of the original species. If species be permanent--if no education or training can educe new kinds--if the higher classes of animals are not the results of meliorations of the lower--whence did they come? This question we are not bound to answer. It might be as reasonably asked, whence did the lower classes come? Geology, like other sciences, does not conduct us to the _beginning_, it only takes up creation at certain ulterior stages of development. The changes and construction of the globe may have been different in different parts; it has not been proved that geological revolutions have been either universal or contemporary. There may have been climates and regions adapted to the existence of the higher class of land animals, while contemporarily therewith other portions of the globe might be undergoing changes beneath the ocean. It is not improbable that the human species dwelt nearly stationary for ages on the old continents of Africa and Asia, while Europe and America were covered with water. Supposing these new continents formed, either by the gradual subsidence of the sea or the rising of its bed, successive inhabitants would follow in the order presented by existing organic remains. While covered by the sea, what now form Europe and America could only be peopled by marine animals; but as the land rose or the waters subsided into their ocean channels, and dry land appeared, reptiles and amphibiæ might become the occupants; next, as the earth became drier and more salubrious, the new continent would be resorted to by terrestrial animals; in a still more advanced stage of purification and salubrity, man himself, as the lord of all the preceding classes of immigrants, would take possession, and as he still continues the living occupant it is premature to look for his petrifaction. ORIGIN OF THE ANIMATED TRIBES. Science has mastered many perplexities, but is almost powerless as ever in generation. All that lives, and still more all that moves, must have a pre-existing germ formed independently of the created being, but which is essential to its existence, and fixes the type of organization. The old adage--_omne animal ab ovo_--may be taken as generally true. But though every animal has its primordial egg or germ, all germs are not identical. In the beginning of life there are other organic elements besides the ovum. Partly on direct proof and partly on good analogy, it may be inferred that these differ in different species--that each in the first stages of existence is bound by a different and immutable mode of development--and, if so, there can be no embryotic identity. "By no change of conditions," says Dr. CLARKE, "can two ova of animals of the same species be developed into different animal species; neither by any provision of identical conditions can two ova of different species be developed into animals of the same kind." If these views be right, and we believe them to be so, there cannot be a transmutation of species under the influence of external circumstances. Baffled in the effort either to create species or organically to change them, attempts have been made to approach nearer to the source of vitality, and explain the chemical, electric, or mechanical laws by which the vital principle is influenced. For this purpose various hypotheses have been put forth; one is the noted conjecture of Lord MONBODDO, that man is only an advanced development of the chimpanzee or ourang-outang. A second explanation is that given by LAMARCK, who surmised, and with much ingenuity attempted to prove, that one being advanced in the course of generations into another, in consequence merely of the experience of wants calling for the exercise of faculties in a particular direction, by which exercise new developments of organs took place, ending in variations sufficient to constitute new species. In this way the swiftness of the antelope, the claws and teeth of the lion, the trunk of the elephant, the long neck of the giraffe have been produced, it is supposed, by a certain plastic character in the construction of animals, operated upon for a long course of ages by the attempts which these animals make to attain objects which their previous organization did not place within their reach. This is what is meant by the hypothesis of _progressive tendencies_, and which requires for its validity not only the assumption of a mere capacity for change, but of active principles conducive to improvement and the attainment of higher powers and faculties. More recently ST. HILAIRE has published a paper in which he speaks of the immutability of species as a conviction that is on the decline, and that the age of CUVIER is on the close. Carried away by what Professor PHILLIPS has called a poetical conjecture that cannot be proved, this writer propounded the speculation that the present crocodiles are really the offspring of crocodilian reptiles, the difference being merely the effect of physical conditions, especially operating during long geological periods upon one original race. The human species, he contends, are but an advanced development of the higher order of the monkey tribe, and that the negroes are degenerating towards that type again. According to him the sivatherium--a fossil animal that had been found in the Himalaya mountains--was the primeval type that time had fined down into the giraffe from long-continued feeding on the branches of trees. Dr. FALCONER and Capt. CAUTLEY, however, have shown that anatomical proofs are all against this inference, but if any doubt remained it must yield to the fact, that among the _fauna_ of the Sewalik hills the sivatherium and the giraffe were contemporaries. The author of the _Vestiges of Creation_ has put forth an hypothesis founded on the preceding conjectures, but more compact and conclusive. He is, as we have seen, in favour of the progressive change of species, adopting the notion that men once had tails, and that the rudiments of this condal appendage are found in an undeveloped state in the _os coccygis_ (p. 199.) His leading idea of the progress of organic life is that the "_simplest and most primitive type under a law to which that of like production is subordinate, gave birth to the type next above it; that this again produced the next higher, and so on to the very highest_, the stages of advance being in all cases very small--namely, from one species only to another; so that the phenomenon has always been of a modest and simple character." (p. 231.) The arguments by which the author endeavours to prove his hypothesis may be thus compressed. According to him foetal development is a science, illustrated by HUNTER'S great collection of the Royal College of Surgeons, and established by the conclusions of ST. HILAIRE and TIEDMANN. Its primary positions are--1. That the embryos of all animals are not distinguishably different from each other; and, 2. That those of all animals pass through a series of phases of development, each of which is the type or analogue of the permanent configuration of tribes inferior to it in the scale. Higher the order of animals, the more numerous its stages of progress. Man himself is not exempt from this law. His first foetal form is that which is permanent in the animalcule; it next passes through ulterior stages, resembling successively a fish, a reptile, a bird, and the lower mammalia before it attains its specific maturity. The period of gestation determines the species; protract it, and the species is advanced to a higher class. This might be done by the force of certain conditions operating upon the system of the mother. Give good conditions and the young she produces will improve in development; give bad conditions and it will recede. Cases of monstrous birth in the human species are appealed to, in which the most important organs are left imperfectly developed; the heart, for instance, having sometimes advanced no further than the three-chambered or reptile form, while there are instances of that organ being left in the two-chambered or fish-like form. These defects arise from a failure of the power of development in the mother, occasioned by misery or bad health, and they are but the converse of those conditions that carry on species to species. The _differences of sexes_ is the result of foetal progress only one degree less marked than that of a change of species. Sex is fully ascertained to be a matter of development. All beings are at one stage of the embryotic progress _female_. A certain number of them are afterwards advanced to the more powerful sex. For proof of this, the economy of bees is cited; when they wish to raise a queen-bee, or true female, they prepare for the larva a more commodious cell, and feed it with delicate food. But we shall here stop to remark on the author's argument up to this point. It is manifest, according to his hypothesis, that neither sex nor species depend on the ancestral germ, but simply on physical conditions and mechanical development. But eminent physiologists deny that the facts are such as he has stated; they deny, as we have stated in a former section, that the foetal progress is such as the _Vestiges_ represent them to be; they deny that the human embryo, for example, exhibits in successive stages the form of fish, lizard, bird, beast: on the contrary, they contend that it is only in the earliest period of the organic germ, when the manifestations are almost too obscure for microscopic sense, that any resemblance exists; that immediately the organic germ becomes sensible to observation, sex and species are found to be fixed. Take, for example, the vertebrata; in these, by some mysterious bond of union, the organic globules are seen to arrange themselves into two nearly parallel rows. We may then say that the keel of the animal is laid down, and in it we have the first rudiments of a backbone and a continuous spinal chord. But during the progress and completion of this first organic process no changes have been observed assimilating the nascent embryo to any of the inferior animals. The next series of changes in the germinal membrane are of two kinds--in one the nervous system, the organs of motion, the intestinal canal, the heart and blood-vessels are manifested; the other set of changes, which are subsequent, produce the perfection of the animal and determine its sex. All these manifestations result from germinal appendages that cannot be severed or changed without ruin to the embryo, and the conditions essential to life as the structure advances are due temperature, due nutriment of the nervous organs, and due access to the atmospheric air. Without, therefore, pursuing further this part of the inquiry, we shall remark that the question at issue between the _Vestiges_ and its opponents is one of facts--of conflicting evidence--to be tried by the jury of the public, or rather by those who, from science or professional pursuits, are competent to form an authoritative opinion. Our own conclusion is, that in face of the testimony adduced against it, the author's hypothesis is not yet established. For proof that species do change, and that even new species have been actually and recently produced, the author has adduced statements certainly as questionable and little satisfactory as his representation of foetal phenomena. We can only briefly enumerate them. First we are told that oats sown at midsummer, if kept cropped down, so as to be prevented shooting into ear, and then allowed to remain in the ground over winter, will spring up next year in the form of rye (p. 226). This need not be disputed about; the experiment can be easily tried; but if rye were the result, it would be no conclusive proof of a translation of species. Perhaps the oat-plants perished under the operation of repeated cuttings, and the rye seed was dormant in the earth and sprung up in its place; or, if not so, oats and rye may not be different species, only varieties of the same species. They are scarcely more dissimilar than the primrose, the cowslip, and the oxlip, which have all been raised from the seed of the same plant, and are now regarded by botanists as varieties instead of species. When lime is laid on waste ground we are told that white clover will spring up spontaneously, and in situations where no clover-seed could have been left dormant in the soil (p. 182). But how is this to be proved? It is certain that seeds will remain dormant in the soil for centuries, and then spring up the first year the soil is turned up by the plough. Some seeds have retained their vitality for thousands of years in the old tombs of Egypt; they have been repeatedly brought to England, sown, and produced good wheat. We are next told that wild pigs never have the measles, they are produced by a _hyatid_ and the result of domestication; that a _tinea_ is found in dressed wool that does not exist in its unwashed state; that a certain insect disdains all food but chocolate, and that the larva of _oinopota cellaris_ only lives in wine and beer. All these are articles manufactured by man, and are adduced as proofs of animal life, independent of any primordial egg. The entoza are dwelt upon; they are creatures living in the interior of other animals, of which the tape-worm that infests the human body is a melancholy instance. In these illustrations we think the author has some show of reason, for we feel convinced that there is such a thing as spontaneous generation from the inorganic substance, wisely provided for clearing the earth of noxious effluvia and putrid matter, and converting them into new elements conducive to health and life. We believe in this source of vitality from its wisdom and necessity, its necessity and wisdom, in our estimate, being strong presumptive proofs of its existence in harmony with the general forecast and economy of nature. Of the self-originating spring of life, some of the examples adduced by the author are proofs, and of which we have familiar illustrations in cheese-mites, maggots in carrion, and the green fly that breeds so profusely in weak and decaying vegetation; in all which by some inscrutable law the organic germ, without an antecedent, appears to evolve from the dead or putrifying mass for its riddance and transmutation. Conceding, however, thus far to the author, we are not prepared to admit that the creative powers of Messrs. CROSSE and WEEKES has been established. These gentlemen are said (p. 190) to have introduced a stranger in the animal kingdom, a species of _acarus_ or mite amidst a solution of silica submitted to the electric current. The insects produced by the action of a galvanic battery continued for eleven months are represented as minute and semi-transparent, and furnished with long bristles. One of the creatures resulting from this elaborate term of gestation was observed in the very act of emerging, in its first-born nudity, and sought concealment in a corner of the apparatus. Some of them were observed to go back into the parent fluid and occasionally they devoured each other; and soon after they were called to life, they were disposed to multiply their species in the common way! So much for the experiment; against its verity it is alleged, first, that the _Acarus Crossii_ are not a new species, or if new, that neither Mr. CROSSE nor Mr. WEEKES, who repeated Mr. CROSSE'S experiment, produced them, but only aided by the voltaic battery the development of the insects from their eggs. Such a mode of generation is contrary to all human experience, and can only be believed in on the strongest corroborative proof. Neither by chemistry nor galvanism can man, we apprehend, be more than instrumental and co-operative, not originally and independently creative. In almost every form of life, whether animal or vegetable, art can multiply varieties,--can train, direct--but cannot form new species. This is the mockery of science. With all its invention and resource, it cannot produce organic originals. It can rear a crab-apple into a golden-pippin, or wild sea-weed into a luxuriant cabbage; it can raise infinite varieties of roses, tulips, and pansies, but can create no new plant, fruit, or flower. Man can make a steam-engine, or a watch, but he cannot make a fly, a midge, or blade of grass. He is an ingenious compiler, but not a creator; and his powers of manufacture and conversion are restricted within narrow boundaries. He cannot wander far in the indulgence of his fancies without being recalled, and compelled to return to the first models set by the Great Architect. The further he strays from primitive types in the effort to improve, by crossing, cutting, and grafting, and proportionably less becomes the procreative force. Hybrids are notoriously sterile. Garden fruit is not permanent, and requires to be renewed from seed. The law seems universal in plants and animals, that the vital energy or germ is less forcible and prolific in the pampered and artificial, than in the natural and wild races. HYPOTHESIS OF THE VITAL PRINCIPLE. It is ascertained that the basis of all vegetable and animal substances consists in nucleated cells--that is, cells having granules within them. Nutriment is converted into these before being assimilated by the system. It has likewise been noted that the globules of the blood are reproduced by the expansion of contained granules; "they are, in short," says the _Vestiges_, "_distinct organisms multiplied by the same fissiporous generation_. So that all animated nature may be said to be based on this mode of origin; _the fundamental form of organic being is a globule, having a new globule forming within itself_, by which it is in time discharged, and which is again followed by another and another, in endless succession. It is of course obvious, that if these globules could be produced by any process from inorganic elements, we should be entitled to say that the fact of a transit from the inorganic to the organic had been witnessed." (p. 176.) "Globules," the author continues, "can be produced in albumen by electricity. _If_, therefore, these globules be identical with the cells which are now held to be reproductive, it _might_ be said that the production of albumen by artificial means is the only step in the process wanting. This has not yet been effected." (p. 177.) These are the advances towards generation by chemistry and electricity. The process, however, according to this detail, appears still far from complete. Albumen is to be produced "by artificial means;" and even then we should doubt entire success. Chemists have long commanded the power to resolve the seeds of animal and vegetable life into their elements; they have analysed them, and shown the exact weight and proportion of each constituent; but they never could put them together again, or, by any similar compound produce the primordial egg or organic germ, from which a living being would arise. A connecting link--a vital spark, or animating soul--is always wanting to complete the existence of the Prometheus of the laboratory. Mark, too, the "_if_," and the "_might_," in this most lame and impotent hypothesis:--"_If_, therefore, these globules be identical with the cells which are held to be reproductive, it _might_ be said," &c. Globules can be easily produced; the passage of the electric fluid through water will produce aerial globules in rapid and expansive movement; boys can produce them with suds and a tobacco-pipe in rapid succession, each, for aught we know, containing a "granule" that multiplies by "fissiporous generation." But these are not organic globules, and the author has committed the great perversion in language or logic of confounding the organic globule of life with the inorganic globule of a chemist. His theory is more fanciful than that of LAMARCK, from whom it is derived, and who had, at least, his _petit corps gelatineux_ to begin with--to commence weaving organic tissue from--but our author's organic globule is not so substantive a conception; and as he does not pretend to be able to produce even this by physical means, he has not made a single step in generation. This we consider the least satisfactory and successful portion of the author's work. It assigns no intelligible cause for the origin of life--it only _begs the question_, by the substitution of one mystery for another. His law of DEVELOPMENT is of the same description,--without sense or significancy, unsupported by applicable facts, and is not so comprehensible a cause of vital changes as LAMARCK'S assigned progressive tendencies of animals to master the appliances essential to their wants. ANIMAL AFFINITIES, INSTINCT, AND REASON. The scheme of the _Vestiges_ is uniformly and consistently worked out; all phenomena are resolved into gravitation and development--the first as the law of inorganic, the latter of organic matter. By the last, however, no new principle is revealed, only a new phrase devised, by the amplified application of which the author's entire system may be said to be _begged_ rather than proved; since development is used in a sense implying an indefinite power of animate and inanimate creation; so that at last we make no new discovery, only grasp a new nomenclature. But the author is always interesting, either by the novel display of facts or the ingenious concatenation of plausibilities. Consistently with his fundamental notion of animal transmutation, he tries to prove a family likeness or affinity from the humblest to the highest species. In this way he seeks to explain the marvel with respect to the huge bulk of many of the tertiary mammalia--the mammoth, mastadon, and megatherium; they were in immediate descent from the cetacea, or whale and dolphin tribe. (p. 267.) Again, human reason is considered no exclusive gift; it exists subordinately in the instinct of brutes, and is alleged to be nothing more than a mode of operation peculiar to the faculties in a humble state of endowment, or early stage of development. CUVIER and NEWTON are only intellectual expansions of a clown; and this notion is extended to moral obliquities, the wicked man being characterised as one "whose highest moral feelings are rudimental." (p. 358.) From a like principle the writer concurs with Dr. PRICHARD, that mankind may have had a common origin; that there exists no diversities of colour or osseous structure not referable to climatable or other plastic agencies influencing the development of the different races, commencing with the lowest, or Negro tribe, and ascending upward through the intermediate aboriginal American, Mongolian, and Malay, to the last and most perfect stage of the Caucasian type. Into the verity of these conclusions we are not called upon to enter; they have been long in controversy, involve a great array of facts and inductive inferences, and we have only referred to them as corollaries or collaterals of the author's hypothetical fabric. RELIGIOUS AND MORAL TENDENCIES. We have no charge of impiety to bring against the _Vestiges_. Final causes, or to express ourselves more intelligibly, a _purpose_ in creation, is nowhere impugned. The Deity is not degraded by impersonification in the form and frailties of mortality, but everywhere the author reverently bows to that august and unsearchable name, acknowledges the grand and benevolent design--the admirable adaptation of every created thing to its end and place, and finally concludes in a strain of grateful and exulting Optimism, that we confess we have not fully arrived at--namely, that everything "is very good." (p. 387.) From this impression we have only one constructive drawback to notice in the author's mechanical but fanciful constitution of the universe, by which a special Providence in the government of the world seems to be dispensed with, and the Almighty is placed in the sinecure position of the Grand Elector of the Abbe SIEYES, with nothing to do. But no divine attribute is abscinded--no glory of Omnipotence dimmed--whether it pleases him to rule by direct interpositions of power, or his own pre-ordained eternal laws. Still less can we detect in the speculative inquiries of the _Vestiges_ conclusions hostile to the moral and social interests of the community. Men are formed to be what they are; vice and crime are the fruits of malorganization, and malorganization is the result of the unfavourable conditions in which the subject of it has been placed, prior or subsequent to birth. These are the author's leading metaphysical inculcations. They impose grave duties upon individuals and upon society, rightly understood and applied, but we cannot discern a hurtful tendency in them. They are useful knowledge, knowledge that it would be well for parents and rulers to master, by showing the importance of education, of favourable circumstances, and of good moral and physical training, for rearing happy, well-ordered, and virtuous members of the community. Supreme in intelligence, man, we firmly believe, is not less supremely blessed in the means of felicity, provided his real nature and position in the scheme of creation were understood, recognised, and carried out. He has his place, his office, and his destiny; he is no enigma but as an individual; "in the mass," as the author emphatically remarks, "he is a mathematical problem." His conduct is uniform and consistent; the result of known and ascertainable causes--causes calculable and predicable in their consequences, as the statistics of crime have incontestibly established. GENERAL CONCLUSIONS ON THE VESTIGES. The heavens are wonderful, and the earth is wonderful, and man, who, by force of intellect, has sought to comprehend the immensity of one and unravel the formation of the other, is hardly less wonderful than either. Still the great mystery remains unriddled; our researches have brought us no nearer the beginning, and the first cause of all continues unapproachable and undefinable as ever. Instead of explaining physical creation, we begin with it; we take the existence of matter for granted, and its attributes for granted, and forthwith begin to fabricate a universe, without first ascertaining whence was matter, or whence the laws by which it is impressed, and has been governed in its evolutions. Nature's greatest phenomena are the celestial spaces and the bodies that fill them; our own planet and its living occupants. Upon each of these, their commencement and subsequent vicissitudes, the _Vestiges of Creation_ have propounded an hypothesis, but one mystery is only sought to be explained by another still more mysterious. For the fiat of a Creator chemical affinities and mechanical laws have been substituted, but aided by these the author has failed to produce a world such as we find it. Hence we are again driven upon the old tradition, the old sacred authority, that the world was created out of nothing; and this is as easy to comprehend as the solution of the _Vestiges_, that it sprang from that which is certainly next to nothing--a heated fog or universal fire-mist. When the author deals with the facts of science he interests and instructs, but when he speculates he only amuses or perplexes, without advancing knowledge. His terse and luminous description of the astral firmament deeply impresses with the might and the magnitude of the vast design; but when he attempts to account for the elimination of suns and worlds, their formation and arrangement, we are struck by the puerile folly of his conjectural presumptions. Descending from this august and glittering canopy to our own planet, we are not less astonished by the exhibition of the extraordinary revolutions it has undergone. Geology is the true historian of the earth. Conducted by the lights it affords, we see an eternity of ages has rolled before us; we discover a series of worlds rising through the depths of ocean from the central sphere of heat, amidst boiling floods and volcanic fires, each new platform of existence, that countless periods of time had been requisite to form, peopled with its own congenial forms of organic life, mostly commencing with the simpler, and ascending by almost imperceptible gradations to the higher and more complex structures of being. We are struck by the correspondence, by the _pari passu_ development and formation of the earth's crust and organic existences, and we are apt hastily to conclude that a relation has subsisted between them, that contemporary changes have been cause and effect, and that the improvement of the earth produced the correlative improvement in animals and plants. This forms the author's second questionable hypothesis; it is plausible, but false--repugnant to fact and correct observation. We have no credible evidence that species have changed, or are changeable by the utmost efforts of art or favouring conditions; all we can effect is to improve them within definite limits, but not alter their characteristic types; and we have certain proof that neither man nor the animal nearly next to him in organization, has changed either in habits, disposition, form, or osseus structure during the last 3,000 years. Resemblance is no proof of identity; and hence, though species run into each other by almost inappreciable shades of difference, it is no proof that they are derivative, or other than isolated and self-dependent creations. That they are such, and shall continue such, seems a fixed canon of Nature, who, apparently, has prescribed to each its circle of amendment and range, that like shall beget like--that nought organic shall exist without ancestral germ--and that the variety of species which constitutes the beauty and order of nature shall by no chance, contrivance, or mingling of races, be confounded. Geological facts are in favour of this conclusion. They attest the appearance of new species, not their improvement. In each species a gradation of improvement, approximating from a lower to the next higher organism, is not perceptible; but each seems to have been made perfect at first, and most suited to the co-existent state of the earth. The earliest reptiles were not reptiles of inferior structure; nor the earliest fishes, birds, or beasts. They were adapted, as we now find them, to their precise sphere of existence, without progressive aptitude, preparatory to a higher and translated condition of being. Geology rather points to the extinction and degeneracy of species than their improvement; and the fossils of the old red sandstone, and of the carboniferous formation, attest a loftier and more magnificent creation of both marine and land products than any now subsisting. For these and other reasons before adduced, we dismiss the hypothesis of animal transmutation as unproved and untenable. It pleases and satisfies superficial views, but confronted with the facts of nature, it vanishes like a baseless vision. Man is _sui generis_, sole and exclusive in organization, without pre-existing type or affinity to other species; and his alleged recent metamorphosis from a monkey, and his first and far more distant one from a snail or a tadpole, are paradoxes only worthy of idle debating clubs. Having attempted to unfold the progression of species by his law of development, the author next essays to explain the commencement of the vital principle itself. But here, too, he must have a beginning, and his "organic globule" answers a similar purpose, in deducing the mystery of life, as his nuclei in the "nebular hypothesis." In both the perplexity and real difficulty is not solved or mastered, but evaded. But we have already remarked on the point, and shall only observe that when the author can elicit _thought_ from inorganic matter, either by chemistry or galvanism, we shall think he has made a step in creation. Until then he does not advance, only deceives himself and readers by verbal subtleties and baseless suppositions. Apart from its hypotheses, the _Vestiges_ form a valuable and interesting work. It is the most complete, elaborate, and--with all its faults of detail, logic, and inference--the most scientific expositor of universal nature yet offered to the world. But its hypotheses are unwarranted, not inductively derived, and can have no hold on men of science, supported as they mostly are by fanciful analogies, facts misunderstood or misstated, and illustrations selected without discrimination or applicability. Theories do sometimes conduce to the discovery of truth, but are often obstructive; occupy the mind, like theological controversy, without advancing science; and are viewed with the same aversion by the philosopher that the political abstractions tendered to the multitude by the demagogue are viewed by the patriotic legislator. The work, however, will live, and deserves to live. The temple of nature has been looked into, not profoundly, perhaps, nor always successfully; but in a fearless spirit, and with a highly-accomplished mind. Had the divine COSMOS been more fully dwelt upon and depicted--had the harmony, beauty, and beneficence of creation been more fully and exclusively displayed--we should have been more gratified; but we are thankful, in the main, for what we have received. An impulse has been given to popular inquiry, and a vast field for discussion opened, from which we can prospectively discern neither less love for man, nor reverence for God. Who the author is we have no certain knowledge. It is not, we suspect, Lord KING, nor Lord THURLOW, nor Lady BYRON; but it may be the author of the _Essay on the Formation of Opinions_, and of the _Principle of Representation_. Mr. BAILEY, of Sheffield, though little known, possesses the fine reasoning powers, intellectual grasp, independence of research, abstract analysis, and attic style, that would qualify him to produce the _Vestiges of Creation_, though we never heard that he is a great natural philosopher. But, as just hinted, deep science is not evinced by the _Vestiges_, only an able, systematic, and tasteful arrangement of its distant and recent advances. "EXPLANATIONS:" A SEQUEL TO THE "VESTIGES OF THE NATURAL HISTORY OF CREATION." (_From the_ ATLAS _of December 20, 1845._) So many strong objections had been arrayed against the _Vestiges of Creation_, that the author was called upon to elucidate and reinforce his argument, or abandon the ground he had taken up. The more candid and equitable of his judges--those who were disposed to try him upon the merits, and independently test the claims of his inquiry, as in fairness it ought to be, as strictly a scientific speculation, regardless of any constructive bearings it might have on current opinions or prejudices--could not arrive at any more favourable conclusion than that he had failed to establish his hypotheses. Indeed this was the only verdict that could be safely delivered in. The impugners of the work were in the same helpless predicament as its author, who had, however, more venturously presumed to unravel unsearchable mysteries, concerning which, in the existing state of science, men can only conjecture, wonder, and adore, utterly unable to affirm or deny aught respecting them. What, for instance, with the remotest semblance of certainty, can be predicated of the stellar orbs? Is it not idle almost to speculate on the impenetrable secret of their origin when their very existence is undefinable--when their end, their glittering discs, and all but immeasurable distances are wholly unapproachable? Nor hardly less beyond our grasp is the commencement of organic existences. We do pride ourselves on recent advances to the sources of entity; we tear up the dead, we torture the living, and sedulously chronicle every beat of the heart and vibration of the brain to slake an insatiable curiosity, yet how unsatisfactory our reach towards the hidden springs of life--how limited our attainments, when the creation of a single blade of grass, the humblest worm, a poor beetle, or gadfly, would baffle the utmost structural skill of the greatest philosopher! Into the fathomless depths of our own globe we have also essayed to penetrate. Poor beings! of three score and ten, whose utmost historical span extends only to some thousands of years, have sought to trammel up the terrene vicissitudes of millions of ages anterior to their own existence! Does not this savour of a vain research, or of a laudable thirst for knowledge? Over all these dark and solemn inscrutabilities, however, the _Vestiges_ undertook to throw a glare of light, to reveal their beginning, progression, order, relations, and law of development. Although daring in aim, the attempt was not to be wholly deprecated. While religious freedom had been secured, philosophy had become timid, official, and timeserving; retentive as FONTENELLE of the truths within its grasp, and fearful to give utterance to aught that might disturb the stillness of the temple, the lecture-room, or fashionable auditory. Modern teachers had been used so long to the Baconian go-cart, that they had become as apprehensive of losing the inductive clue as the PALINURUSES of old of the sight of the directing shore. But the time had arrived when it seemed expedient to relax the strictness of the investigative rule, and afford scope for a more systematic, if not speculative research. Science had made great acquisitions, and it seemed desirable, if only for experiment sake, to see what kind of FRANKENSTEIN would result from the architectural union of her scattered limbs. This formed the scope of the _Vestiges of Creation_; novelties were not propounded, only a portentous skeleton raised from the truths physical astronomy, geology, chemistry, physiology, and natural history had established. Does the author recoil from his work? No; these _Explanations_ attest that he is steadfast in the worship of the idol of his brain. He retracts nothing, he re-asserts, elucidates, and often dexterously turns the weapons of the most formidable and orthodox of his adversaries against them, by showing from their writings that they had, in detail at least, acquiesced in the truths that they now, in a generalised form, seek to controvert and repudiate. So much adroitness and pertinacity in the author can hardly fail to provoke resistance, if not asperity, despite of the imperturbable temper in which he maintains the combat. The learned have been disturbed in their daily routine, by the discharge from an unknown hand, of a massive pyrites, that has diffused as much consternation among the herd of modish elocutionists, college tutors, and chimpanzee professors, as Jove's ligneous projectile among the lieges of the standing pool. For this commotion we have, on a former occasion, conceded that there existed valid reasons, and we hasten to see the way in which they have been met in the rejoinder before us; contenting ourselves, as we needs must, by briefly noticing some of the salient points of the controversy. First of the Nebular Hypothesis. The chief objection to this theory is, that the existence of nebulous matter in the heavens is disproved by the discoveries made by the telescope of the Earl of ROSSE. By the reach of this wondrous tube, masses of light, rendered apparently nebulous by their vast distance, have been resolved into clusters of stars, and thence the assumption seemed unwarrantable that any luminous matter, different from the solid bodies composing planetary systems existed in the heavenly spaces. But to this the author replies, that there are two classes of nebulæ--one resolvable into constellations--another comparatively near, that remains unaffected by telescopic power, and that until this last description can be separated, the nebular hypothesis is not disproved. It is thus brought to an issue of facts, both as to the existence of nebulæ of this latter kind, and the optical power to resolve them into distinct stars. But the author can hardly claim this negative success in grappling with a second objection--namely, his assumed origin of _rotatory motion_. According to him, a confluence of atoms round a spherical centre of attraction, would cause the agglomerated mass to revolve upon its axis in the manner of our earth. This was denied by everybody the least acquainted with the laws of motion; and thus did one of his imaginary solutions of a great phenomenon of the universe fall dead to the ground. This he now seems to concede, but in a sentence unintelligible to us, in which an undoubted physical law is spoken of as only an _abstract truth_ (p. 20). He obviously still clings to his first mistaken inference, and calls to his aid Professor NICHOL, whom he has also pressed into his service to help him over the last-mentioned difficulty by the Professor's affirmation of a diversity of nebulous clusters. But the Professor does not commit himself to the extent of the author; his aqueous whirlpool is cited from HERSCHEL, only in illustration, and correctly said to be produced by the unequal force of convergence of a fluid to a common centre. But the author's nuclei, disposed in his notable "fire-mist," did not act with unequal force on the ambient vapour, and whose central convergence in consequence, would not produce rotation or motion of any kind. This was the real matter in question, the author was taken up on his own premises, and the results he assumed to follow from them proved to be inconsistent with the unquestionable laws of gravitating matter. He has gone over the geological portion of his subject with much care, but if competent, it would be impossible within our narrow limits to accompany him; nor could the discussion be made either interesting or intelligible except to the scientific, who have devoted attention to an extremely curious, but still obscure and unsettled field of investigation. He has elaborately cleared up many points, and successfully, we think, answered some weighty objections, but we are not yet converts to his theory of organic development. One passage we shall extract; after adverting to the facts established by powerful evidence, that during the long term of the earth's existence, strata of various thickness were deposited in seas composed of matter worn away from the previous rocks; that these strata by volcanic agency were raised into continents, or projected into mountain chains, and that sea and land have been constantly interchanging conditions. He continues:-- "The remains and traces of plants and animals found in the succession of strata show that, while these operations were going on, the earth gradually became the theatre of organic being, simple forms appearing first, and more complicated afterwards. _A time when there was no life_ is first seen. We then _see life begin, and go on_; but whole ages elapsed before man came to crown the work of nature. This is a wonderful revelation to have come upon the men of our time, and one which the philosophers of the days of Newton could never have expected to be vouchsafed. The great fact established by it is, that the organic creation, as we now see it, was not placed upon the earth at once; it observed a PROGRESS. Now we can _imagine_ the Deity calling a young plant or animal into existence instantaneously; but we see that he does not usually do so. The young plant and also the young animal go through a series of conditions, advancing them from a mere germ to the fully developed repetition of the respective parental forms. So, also, we can _imagine_ Divine power evoking a whole creation into being by one word; but we find that such had not been his mode of working in that instance, for geology fully proves that organic creation passed through a series of stages before the highest vegetable and animal forms appeared. Here we have the first hint of organic creation having arisen in the manner of natural order. The analogy does not prove identity of causes, but it surely points very broadly to natural order or law having been the mode of procedure in both instances." To the allusion in the last sentence there can be no demur; that there is "natural order or law" in creation who will contest? But it is the author's law and the author's order that are in dispute--his transmutation of species, the higher classes emerging from and partly annihilating the lower, under meliorated conditions of being. That the simpler form of organic life should first appear; that remains of invertebrated animals should be first found; then, with these, fish, being the lowest of the vertebrated; next, reptiles and birds, which occupy higher grades; and finally, along with the rest, mammifers, the highest of all--all this appears natural enough. _How could it be otherwise?_ When the earth was a slimy bed, what but the lowest forms of life--the mollusca, and other soft animals, without bony structure--could possibly live in or occupy it? During the carboniferous era, when the earth was enveloped in an atmosphere of hydrogen, vegetation might thrive; but man, and animals like him, dependent on vital air, could not exist; nor are remains of them found in this epoch of the globe's vicissitudes. All this is comprehensible. But the perplexing inquiry is, whence did the successive grades of animals emerge? That they could not contemporaneously exist; when the whole earth was a shoreless sea, and that animals could not live is certain; but were they created in succession by the Divine fiat, or did they emerge, as our author supposes and elaborately tries to prove, from the humblest primitive forms, by an inscrutable law of progression--evidenced, he contends, by geological facts--though by some his facts are disputed--and certainly not confirmed by any animal changes observable within the limits of human experience? There is another alternative offers, which would dispense both with the author's hypothesis and the need of successive organic creations by a special Providence. Is it a geological fact, since life began, that the earth has _simultaneously_ undergone throughout its entire surface the revolutions assigned to it? May it not always, from that period, have consisted, as it now does, of water and dry land, alternately changing their sites, but always apart, and allowing of the contemporary existence on some portion of its surface of all the varieties of tribes ever found upon it? The fossiliferous rocks that formed the primeval sea-beds could only be deposited by the abrasion from the anterior and higher rocks. It has always appeared to us that this conjecture is worthy of consideration, and, if found tenable, would reconcile many perplexities. Upon subjects so obscure, and to which the human intellect has been only recently directed, it is not surprising that men of science have not arrived at uniformity of conclusion. Unable to reconcile phenomena with positive knowledge, there are names of no mean repute who would reserve certain domains of creation as the fields of special interventions. To this class Dr. WHEWELL appears to belong, who assumes that "events not included in the _course of nature_ have formerly taken place." In the same way Professor SEDGWICK, to account for the appearance of certain animals, says, "They were not called into being by any law of nature, but by a power above nature." He adds, "they were created by the hand of GOD, and adapted to the conditions of the period." To this the author of the _Vestiges_ assents, with the explanation (p. 134) that their existence was not the result of a "special exertion of power to meet special conditions," but of an antecedent and primitive law of development suited to the new exigencies, and emanating from the Creator. This, he contends, does not lower our estimate of the Divine character; and, in proof, cites Dr. DODDRIDGE, who cannot be suspected of irreverence. "When we assert," says the pious and amiable author, "a perpetual Divine agency, we readily acknowledge that matters are so contrived as not to need a Divine interposition in a different manner from that in which it had been constantly exerted. And it must be evident that an unremitting energy, displayed in such circumstances, _greatly exalts our idea of God, instead of depressing it_; and, therefore, by the way, is so much more likely to be true." Against constructive inferences it is urged, in the _Explanations_-- "As to results which may flow from any particular view which reason may show as the best supported, I must firmly protest against any assumed title in an opponent to pronounce what these are. The first object is to ascertain truth. No truth can be derogatory to the presumed fountain of all truth. The derogation must lie in the erroneous construction which a weak human creature puts upon the truth. And practically it is the true infidel state of mind which prompts apprehension regarding any fact of nature, or any conclusion of sound argument." The writer then quotes Sir JOHN HERSCHELL as having some years ago announced views strictly conformable to those subsequently taken of organic creation in the _Vestiges_:-- "'For my part,' says Sir John, 'I cannot but think it an inadequate conception of the Creator, to assume it as granted that his combinations are exhausted upon any one of the theatres of their former exercise, though, in this, as in all his other works, we are led, by _all analogy_, to suppose that he operates through a series of intermediate causes, and that, in consequence, _the origination of fresh species, could it ever come under our cognizance, would be found to be a natural, in contradistinction to a miraculous process_,--although we perceive no indications of any process actually in progress which is likely to issue in such a result. In his address to the British Association at Cambridge, (1845), he said with respect to the author's hypothesis of the first step of organic creation--'The transition from an inanimate crystal to a globule capable of such endless organic and intellectual development, is as great a step--as unexplained a one--as unintelligible to us--and in any sense of the word as _miraculous_, as the immediate creation and introduction upon earth, of every species and every individual would be!'" The Rev. Dr. PYE SMITH is next adduced:-- "'Our most deeply investigated views of the Divine Government,' says he, 'lead to the conviction that it is exercised in the way of _order_, or what we usually call _law_. God reigns according to immutable principles, that is _by law_, in _every part of his kingdom--the mechanical, the intellectual, and the moral_; and it appears to be most clearly a position arising out of that fact, that _a comprehensive germ which shall necessarily evolve all future developments_, down to the minutest atomic movements, is a more suitable attribution to the Deity, than the idea of a necessity for irregular interferences.'" Lastly, the reviewer of the _Vestiges_ in _Blackwood's Magazine_, who is understood to be a naturalist of distinguished ability, expresses himself in an equally decided manner:-- "To reduce to a system the acts of creation, or the development of the several forms of animal life, no more impeaches the authorship of creation, than to trace the laws by which the world is upheld, and its phenomena perpetually renewed. The presumption naturally rises in the mind, that the same Great Being would adopt the same mode of action in both cases.... To a mind accustomed, as is every educated mind, to regard the operations of Deity as essentially differing from the limited, sudden, evanescent impulses of a human agent, it is distressing to be compelled to picture to itself, the power of God as put forth _in any other manner than in those slow, mysterious, universal laws, which have so plainly an eternity to work in;_ it pains the imagination to be obliged to assimilate those operations, for a moment, to the brief energy of a human will, or the manipulations of a human hand.... No, there is nothing atheistic, nothing irreligious, in the attempt to conceive creation, as well as reproduction, carried on by universal laws." We have dwelt so much upon this matter because it is one in which popular feelings are likely to be most deeply interested. We shall give the author, too, the benefit of his _Explanations_ on another point, elucidating his former statement of the transmutation of a crop of oats into a crop of rye:-- "'At the request,' says Dr. Lindley, 'of the Marquis of Bristol, the Reverend Lord Arthur Hervey, in the year 1843, sowed a handful of oats, treated them in the manner recommended, by continually stopping the flowering stems, and the produce, in 1844, has been for the most part ears of a very slender barley, having much the appearance of rye, with a little wheat, and some oats; samples of which are, by the favour of Lord Bristol, now before us.' The learned writer then adverts to the 'extraordinary, but certain fact, that in orchidaceous plants, forms just as different as wheat, barley, rye, and oats, have been proved by the most rigorous evidence, to be accidental variations of one common form, brought about no one knows how, but before our eyes, and rendered permanent by equally mysterious agency. Then says Reason, if they occur in orchidaceous plants, why should they not also occur in corn plants? for it is not likely that such vagaries will be confined to one little group in the vegetable kingdom; it is more rational to believe them to be a part of the _general system_ of creation.... How can we be _sure_, that wheat, rye, oats, and barley, are not all accidental off-sets from some unsuspected species?'" It may be so; but this would only prove that the "unsuspected species" included greater varieties, not that a really defined species was transmutable into another. But it is a point upon which no satisfactory result can be arrived at, since naturalists are not agreed in the classification of species, nor what attributes constitute one. The Broomfield experiment is again brought forward, as decisive of the power to originate new life from inorganic elements. It will be remembered that Mr. WEEKES, of Sandwich, continued during three years to subject solutions to electric action, and invariably found insects produced in these instances, while they as invariably failed to appear where the electric action was not employed, but every other condition fulfilled. In a letter to the author of the _Vestiges_--two are inserted, one on the independent generation of fungi--Mr. WEEKES says-- "One hundred and sixty-six days from the commencement of the experiment--the first acari seen in connexion therewith, six in number and nearly full-grown, were discovered on the outside of the open glass vessel. On removing two pieces of card which had been laid over the mouth of this vessel, several fine specimens were found inhabiting the under surfaces, and others completely developed and in active motion here and there within the glass. Making my visit at an hour when a more favourable light entered the room, swarms of acari were found on the cards, about the glass tumbler, both within and without, and also on the platform of the apparatus. At this identical hour Dr. J. Black favoured me with a call, inspected the arrangements, and received six living specimens of the acarus produced from solution in the open vessel." Specimens of the insect were sent to Paris, when they set a whole conclave of philosophers a-laughing, because they were found to contain ova. Other specimens were sent to London, but there their fate was sealed by their being found to be, not a new species, but one then abundant in the country. For ourselves we think the experiment not conclusive. We adopt HUME'S principle. All but universal experience having established that life is _ex ovo_ only, we must have a proportionate body of counter evidence to establish a different mode of generation. At all events, Mr. WEEKES'S protracted gestation of 166 days by his galvanic battery is not likely, in the existing rage for despatch, to supersede the existing routine of reproduction. LONDON: PRINTED BY C. WHITING, BEAUFORT HOUSE, STRAND. THE ATLAS, A General Family Newspaper and Journal of Literature. * * * * * This Periodical, which may be justly called a Weekly Cyclopædia of Politics, Literature, Arts, and Science, is published every Saturday afternoon, in time for the post, containing the News of Saturday. * * * * * THE ATLAS IS DIVIDED INTO TWO PRINCIPAL DEPARTMENTS, NEWS AND LITERATURE, And these are subdivided and classified with care and industry into heads of easy reference, so that each particular subject is preserved distinct and entire. The dimensions of the sheet, which folds into sixteen large quarto-sized pages, containing forty-eight columns, afford this classification facilities which few other publications possess. * * * * * NEWS. PARLIAMENTARY DEBATES reported on a scale of magnitude far exceeding other weekly Journals. PARLIAMENTARY PAPERS, a digest of all Parliamentary documents of obvious reference and popular utility. FOREIGN NEWS, the current events in foreign countries, arranged in the form of historical narrative, collated carefully from contemporary authorities, and distributed under the heads of the different countries and colonies to which they belong. BRITISH NEWS, a clear epitome of all domestic occurrences, under the various heads of Public Meetings, Trade, Agriculture, Accidents and Offences, Police, Proceedings of the Courts of Law and Sessions, Court and Fashionable News, Church and University Intelligence, Military and Naval Affairs copiously given, the Money Market, and the miscellaneous news of the week up to midnight on Saturday. The Local News of Ireland and Scotland, under separate heads. In the conduct of this department of the ATLAS recourse is had to many exclusive sources of information, and correspondents have been established who furnish expressly the latest intelligence. The Gazettes and Tables of Markets, and all matters interesting to the Commercial World, are especially attended to. Preserving an independence in its editorial capacity, the ATLAS affords a faithful reflection of the opinions and proceedings of all political parties. The attention that is observed in the purity of language and selection of subjects, down to the minutest paragraph in the ATLAS, recommends it especially to the use of families and the guardians of youth; and the copious details it affords of Military and Naval Affairs, invest it with valuable attractions for the members of these professions, and the residents in the Colonies. LITERATURE. The Contributions to this department are from the pens of Professors and Gentlemen of acknowledged reputation, and are classified under the following heads:-- 1.--ORIGINAL ESSAYS ON MEN AND THINGS, embodying a lively commentary on passing events and men and manners. 2.--THEATRICAL CRITICISMS upon the written and acted Drama, in which both are reviewed in a spirit of truth and perfect candour. 3.--REVIEWS of all new works of ability, with numerous extracts. Independent and free from all literary and personal prejudices, the opinions of the Reviewers in the ATLAS may be consulted with confidence in their integrity. 4.--LITERARY MEMORANDA, notes of all novelties in literature abroad and at home, and summary criticisms on all works of minor importance. 5.--MUSIC AND MUSICIANS, or scientific criticisms on vocal and instrumental performers, operas, and new music, on the Continent as well as in England, with occasional engraved illustrations. 6.--FINE ARTS, Weekly notices of pictorial exhibitions, and critical descriptions of paintings, drawings, and engravings, with commentaries on all new works of art. 7.--SCIENTIFIC NOTICES, or descriptions of improvements in Mechanics and the experimental Sciences, illustrated occasionally by diagrams, with an account of New Patents, Meteorological Tables, Proceedings of Literary and Scientific Institutions, &c. The Literary division of the ATLAS in the various branches has formed an era in the class of publications in which it ranks; and exhibits a remarkable union of the essential features of the more elaborate Reviews, with the popular and practical objects of the General Newspaper. * * * * * Published for the Proprietor, at the office, 6, Southampton-street, Strand, London.--Price Eight Pence. Orders received by all Newsmen throughout the Kingdom. _In one volume octavo, cloth lettered, price Five Shillings,_ NATIONAL DISTRESS, ITS CAUSES AND REMEDIES; A Prize Essay AS ORIGINALLY PUBLISHED IN "THE ATLAS." * * * * * By SAMUEL LAING, Esq., Jun., _Late Fellow of St. John's, Cambridge._ * * * * * PART I. Chap. I.--General Considerations--Absence of the usual Historical Symptoms of National Decline--Definition of the Evils which Threaten Society. Chap. II.--Official Pauperism and Unrecognised Destitution--Evidence respecting the Condition of the Lower Classes in Large Towns. Chap. III.--Extent of Destitution in Large Towns--Condition of Hand-loom Weavers and other Classes of Unskilled Manufacturing Operatives. Chap. IV.--Condition of Class of Agricultural Labourers. Chap. V.--Condition of Classes of Labouring Population employed in Mines, Fisheries, Canals, Railways, &c. Chap. VI.--Condition of Classes Superior to Common Labourers--General View of Society in Great Britain. PART II. Chap. I.--General Views--Modern Theories of Society--Effect and Paramount Importance of Moral Causes. Chap. II.--Economical Causes--Population--Theory of Malthus. Chap. III.--Economical Causes, continued--Revolution in the Course of Industry effected by Machinery--Extension of Manufactures--Factory System, &c. Chap. IV.--Foreign Competition. PART III. Chap. I.--Free Trade, Corn Laws. Chap. II.--Free Trade, continued--New Tariff, Provisions, Sugar, &c. Reciprocity System--Commercial Treaties. Chap. III.--Taxation. Chap. IV.--Currency and Banking. Chap. V.--Emigration. Chap. VI.--Poor Laws. Chap. VII.--Sanitary and Building Regulations, &c. Chap. VIII.--Education. Chap. IX.--Conclusion. * * * * * LONDON: Published by Longman and Co.; Simpkin and Marshall; And Whittaker and Co. also, At the Atlas Office, 6, Southampton-street, Strand. 
2089	----	ON THE RECEPTION OF THE 'ORIGIN OF SPECIES' by PROFESSOR THOMAS HENRY HUXLEY FROM THE LIFE AND LETTERS OF CHARLES DARWIN EDITED BY FRANCIS DARWIN ON THE RECEPTION OF THE 'ORIGIN OF SPECIES.' To the present generation, that is to say, the people a few years on the hither and thither side of thirty, the name of Charles Darwin stands alongside of those of Isaac Newton and Michael Faraday; and, like them, calls up the grand ideal of a searcher after truth and interpreter of Nature. They think of him who bore it as a rare combination of genius, industry, and unswerving veracity, who earned his place among the most famous men of the age by sheer native power, in the teeth of a gale of popular prejudice, and uncheered by a sign of favour or appreciation from the official fountains of honour; as one who in spite of an acute sensitiveness to praise and blame, and notwithstanding provocations which might have excused any outbreak, kept himself clear of all envy, hatred, and malice, nor dealt otherwise than fairly and justly with the unfairness and injustice which was showered upon him; while, to the end of his days, he was ready to listen with patience and respect to the most insignificant of reasonable objectors. And with respect to that theory of the origin of the forms of life peopling our globe, with which Darwin's name is bound up as closely as that of Newton with the theory of gravitation, nothing seems to be further from the mind of the present generation than any attempt to smother it with ridicule or to crush it by vehemence of denunciation. "The struggle for existence," and "Natural selection," have become household words and every-day conceptions. The reality and the importance of the natural processes on which Darwin founds his deductions are no more doubted than those of growth and multiplication; and, whether the full potency attributed to them is admitted or not, no one doubts their vast and far-reaching significance. Wherever the biological sciences are studied, the 'Origin of Species' lights the paths of the investigator; wherever they are taught it permeates the course of instruction. Nor has the influence of Darwinian ideas been less profound, beyond the realms of Biology. The oldest of all philosophies, that of Evolution, was bound hand and foot and cast into utter darkness during the millennium of theological scholasticism. But Darwin poured new life-blood into the ancient frame; the bonds burst, and the revivified thought of ancient Greece has proved itself to be a more adequate expression of the universal order of things than any of the schemes which have been accepted by the credulity and welcomed by the superstition of seventy later generations of men. To any one who studies the signs of the times, the emergence of the philosophy of Evolution, in the attitude of claimant to the throne of the world of thought, from the limbo of hated and, as many hoped, forgotten things, is the most portentous event of the nineteenth century. But the most effective weapons of the modern champions of Evolution were fabricated by Darwin; and the 'Origin of Species' has enlisted a formidable body of combatants, trained in the severe school of Physical Science, whose ears might have long remained deaf to the speculations of a priori philosophers. I do not think any candid or instructed person will deny the truth of that which has just been asserted. He may hate the very name of Evolution, and may deny its pretensions as vehemently as a Jacobite denied those of George the Second. But there it is--not only as solidly seated as the Hanoverian dynasty, but happily independent of Parliamentary sanction--and the dullest antagonists have come to see that they have to deal with an adversary whose bones are to be broken by no amount of bad words. Even the theologians have almost ceased to pit the plain meaning of Genesis against the no less plain meaning of Nature. Their more candid, or more cautious, representatives have given up dealing with Evolution as if it were a damnable heresy, and have taken refuge in one of two courses. Either they deny that Genesis was meant to teach scientific truth, and thus save the veracity of the record at the expense of its authority; or they expend their energies in devising the cruel ingenuities of the reconciler, and torture texts in the vain hope of making them confess the creed of Science. But when the peine forte et dure is over, the antique sincerity of the venerable sufferer always reasserts itself. Genesis is honest to the core, and professes to be no more than it is, a repository of venerable traditions of unknown origin, claiming no scientific authority and possessing none. As my pen finishes these passages, I can but be amused to think what a terrible hubbub would have been made (in truth was made) about any similar expressions of opinion a quarter of a century ago. In fact, the contrast between the present condition of public opinion upon the Darwinian question; between the estimation in which Darwin's views are now held in the scientific world; between the acquiescence, or at least quiescence, of the theologians of the self-respecting order at the present day and the outburst of antagonism on all sides in 1858-9, when the new theory respecting the origin of species first became known to the older generation to which I belong, is so startling that, except for documentary evidence, I should be sometimes inclined to think my memories dreams. I have a great respect for the younger generation myself (they can write our lives, and ravel out all our follies, if they choose to take the trouble, by and by), and I should be glad to be assured that the feeling is reciprocal; but I am afraid that the story of our dealings with Darwin may prove a great hindrance to that veneration for our wisdom which I should like them to display. We have not even the excuse that, thirty years ago, Mr. Darwin was an obscure novice, who had no claims on our attention. On the contrary, his remarkable zoological and geological investigations had long given him an assured position among the most eminent and original investigators of the day; while his charming 'Voyage of a Naturalist' had justly earned him a wide-spread reputation among the general public. I doubt if there was any man then living who had a better right to expect that anything he might choose to say on such a question as the Origin of Species would be listened to with profound attention, and discussed with respect; and there was certainly no man whose personal character should have afforded a better safeguard against attacks, instinct with malignity and spiced with shameless impertinences. Yet such was the portion of one of the kindest and truest men that it was ever my good fortune to know; and years had to pass away before misrepresentation, ridicule, and denunciation, ceased to be the most notable constituents of the majority of the multitudinous criticisms of his work which poured from the press. I am loth to rake any of these ancient scandals from their well-deserved oblivion; but I must make good a statement which may seem overcharged to the present generation, and there is no piece justificative more apt for the purpose, or more worthy of such dishonour, than the article in the 'Quarterly Review' for July, 1860. (I was not aware when I wrote these passages that the authorship of the article had been publicly acknowledged. Confession unaccompanied by penitence, however, affords no ground for mitigation of judgment; and the kindliness with which Mr. Darwin speaks of his assailant, Bishop Wilberforce (vol. ii.), is so striking an exemplification of his singular gentleness and modesty, that it rather increases one's indignation against the presumption of his critic.) Since Lord Brougham assailed Dr. Young, the world has seen no such specimen of the insolence of a shallow pretender to a Master in Science as this remarkable production, in which one of the most exact of observers, most cautious of reasoners, and most candid of expositors, of this or any other age, is held up to scorn as a "flighty" person, who endeavours "to prop up his utterly rotten fabric of guess and speculation," and whose "mode of dealing with nature" is reprobated as "utterly dishonourable to Natural Science." And all this high and mighty talk, which would have been indecent in one of Mr. Darwin's equals, proceeds from a writer whose want of intelligence, or of conscience, or of both, is so great, that, by way of an objection to Mr. Darwin's views, he can ask, "Is it credible that all favourable varieties of turnips are tending to become men;" who is so ignorant of paleontology, that he can talk of the "flowers and fruits" of the plants of the carboniferous epoch; of comparative anatomy, that he can gravely affirm the poison apparatus of the venomous snakes to be "entirely separate from the ordinary laws of animal life, and peculiar to themselves;" of the rudiments of physiology, that he can ask, "what advantage of life could alter the shape of the corpuscles into which the blood can be evaporated?" Nor does the reviewer fail to flavour this outpouring of preposterous incapacity with a little stimulation of the odium theologicum. Some inkling of the history of the conflicts between Astronomy, Geology, and Theology, leads him to keep a retreat open by the proviso that he cannot "consent to test the truth of Natural Science by the word of Revelation;" but, for all that, he devotes pages to the exposition of his conviction that Mr. Darwin's theory "contradicts the revealed relation of the creation to its Creator," and is "inconsistent with the fulness of his glory." If I confine my retrospect of the reception of the 'Origin of Species' to a twelvemonth, or thereabouts, from the time of its publication, I do not recollect anything quite so foolish and unmannerly as the 'Quarterly Review' article, unless, perhaps, the address of a Reverend Professor to the Dublin Geological Society might enter into competition with it. But a large proportion of Mr. Darwin's critics had a lamentable resemblance to the 'Quarterly' reviewer, in so far as they lacked either the will, or the wit, to make themselves masters of his doctrine; hardly any possessed the knowledge required to follow him through the immense range of biological and geological science which the 'Origin' covered; while, too commonly, they had prejudiced the case on theological grounds, and, as seems to be inevitable when this happens, eked out lack of reason by superfluity of railing. But it will be more pleasant and more profitable to consider those criticisms, which were acknowledged by writers of scientific authority, or which bore internal evidence of the greater or less competency and, often, of the good faith, of their authors. Restricting my survey to a twelvemonth, or thereabouts, after the publication of the 'Origin,' I find among such critics Louis Agassiz ("The arguments presented by Darwin in favor of a universal derivation from one primary form of all the peculiarities existing now among living beings have not made the slightest impression on my mind." "Until the facts of Nature are shown to have been mistaken by those who have collected them, and that they have a different meaning from that now generally assigned to them, I shall therefore consider the transmutation theory as a scientific mistake, untrue in its facts, unscientific in its method, and mischievous in its tendency."--Silliman's 'Journal,' July, 1860, pages 143, 154. Extract from the 3rd volume of 'Contributions to the Natural History of the United States.'); Murray, an excellent entomologist; Harvey, a botanist of considerable repute; and the author of an article in the 'Edinburgh Review,' all strongly adverse to Darwin. Pictet, the distinguished and widely learned paleontogist of Geneva, treats Mr. Darwin with a respect which forms a grateful contrast to the tone of some of the preceding writers, but consents to go with him only a very little way. ("I see no serious objections to the formation of varieties by natural selection in the existing world, and that, so far as earlier epochs are concerned, this law may be assumed to explain the origin of closely allied species, supposing for this purpose a very long period of time." "With regard to simple varieties and closely allied species, I believe that Mr. Darwin's theory may explain many things, and throw a great light upon numerous questions."--'Sur l'Origine de l'Espece. Par Charles Darwin.' 'Archives des Sc. de la Bibliotheque Universelle de Geneve,' pages 242, 243, Mars 1860.) On the other hand, Lyell, up to that time a pillar of the anti-transmutationists (who regarded him, ever afterwards, as Pallas Athene may have looked at Dian, after the Endymion affair), declared himself a Darwinian, though not without putting in a serious caveat. Nevertheless, he was a tower of strength, and his courageous stand for truth as against consistency, did him infinite honour. As evolutionists, sans phrase, I do not call to mind among the biologists more than Asa Gray, who fought the battle splendidly in the United States; Hooker, who was no less vigorous here; the present Sir John Lubbock and myself. Wallace was far away in the Malay Archipelago; but, apart from his direct share in the promulgation of the theory of natural selection, no enumeration of the influences at work, at the time I am speaking of, would be complete without the mention of his powerful essay 'On the Law which has regulated the Introduction of New Species,' which was published in 1855. On reading it afresh, I have been astonished to recollect how small was the impression it made. In France, the influence of Elie de Beaumont and of Flourens--the former of whom is said to have "damned himself to everlasting fame" by inventing the nickname of "la science moussante" for Evolutionism (One is reminded of the effect of another small academic epigram. The so-called vertebral theory of the skull is said to have been nipped in the bud in France by the whisper of an academician to his neighbour, that, in that case, one's head was a "vertebre pensante."),--to say nothing of the ill-will of other powerful members of the Institut, produced for a long time the effect of a conspiracy of silence; and many years passed before the Academy redeemed itself from the reproach that the name of Darwin was not to be found on the list of its members. However, an accomplished writer, out of the range of academical influences, M. Laugel, gave an excellent and appreciative notice of the 'Origin' in the 'Revue des Deux Mondes.' Germany took time to consider; Bronn produced a slightly Bowdlerized translation of the 'Origin'; and 'Kladderadatsch' cut his jokes upon the ape origin of man; but I do not call to mind that any scientific notability declared himself publicly in 1860. (However, the man who stands next to Darwin in his influence on modern biologists, K.E. von Baer, wrote to me, in August 1860, expressing his general assent to evolutionist views. His phrase, "J'ai enonce les memes idees...que M. Darwin" (volume ii.) is shown by his subsequent writings to mean no more than this.) None of us dreamed that, in the course of a few years, the strength (and perhaps I may add the weakness) of "Darwinismus" would have its most extensive and most brilliant illustrations in the land of learning. If a foreigner may presume to speculate on the cause of this curious interval of silence, I fancy it was that one moiety of the German biologists were orthodox at any price, and the other moiety as distinctly heterodox. The latter were evolutionists, a priori, already, and they must have felt the disgust natural to deductive philosophers at being offered an inductive and experimental foundation for a conviction which they had reached by a shorter cut. It is undoubtedly trying to learn that, though your conclusions may be all right, your reasons for them are all wrong, or, at any rate, insufficient. On the whole, then, the supporters of Mr. Darwin's views in 1860 were numerically extremely insignificant. There is not the slightest doubt that, if a general council of the Church scientific had been held at that time, we should have been condemned by an overwhelming majority. And there is as little doubt that, if such a council gathered now, the decree would be of an exactly contrary nature. It would indicate a lack of sense, as well as of modesty, to ascribe to the men of that generation less capacity or less honesty than their successors possess. What, then, are the causes which led instructed and fair-judging men of that day to arrive at a judgment so different from that which seems just and fair to those who follow them? That is really one of the most interesting of all questions connected with the history of science, and I shall try to answer it. I am afraid that in order to do so I must run the risk of appearing egotistical. However, if I tell my own story it is only because I know it better than that of other people. I think I must have read the 'Vestiges' before I left England in 1846; but, if I did, the book made very little impression upon me, and I was not brought into serious contact with the 'Species' question until after 1850. At that time, I had long done with the Pentateuchal cosmogony, which had been impressed upon my childish understanding as Divine truth, with all the authority of parents and instructors, and from which it had cost me many a struggle to get free. But my mind was unbiassed in respect of any doctrine which presented itself, if it professed to be based on purely philosophical and scientific reasoning. It seemed to me then (as it does now) that "creation," in the ordinary sense of the word, is perfectly conceivable. I find no difficulty in imagining that, at some former period, this universe was not in existence; and that it made its appearance in six days (or instantaneously, if that is preferred), in consequence of the volition of some pre-existent Being. Then, as now, the so-called a priori arguments against Theism; and, given a Deity, against the possibility of creative acts, appeared to me to be devoid of reasonable foundation. I had not then, and I have not now, the smallest a priori objection to raise to the account of the creation of animals and plants given in 'Paradise Lost,' in which Milton so vividly embodies the natural sense of Genesis. Far be it from me to say that it is untrue because it is impossible. I confine myself to what must be regarded as a modest and reasonable request for some particle of evidence that the existing species of animals and plants did originate in that way, as a condition of my belief in a statement which appears to me to be highly improbable. And, by way of being perfectly fair, I had exactly the same answer to give to the evolutionists of 1851-8. Within the ranks of the biologists, at that time, I met with nobody, except Dr. Grant, of University College, who had a word to say for Evolution--and his advocacy was not calculated to advance the cause. Outside these ranks, the only person known to me whose knowledge and capacity compelled respect, and who was, at the same time, a thorough-going evolutionist, was Mr. Herbert Spencer, whose acquaintance I made, I think, in 1852, and then entered into the bonds of a friendship which, I am happy to think, has known no interruption. Many and prolonged were the battles we fought on this topic. But even my friend's rare dialectic skill and copiousness of apt illustration could not drive me from my agnostic position. I took my stand upon two grounds: firstly, that up to that time, the evidence in favour of transmutation was wholly insufficient; and secondly, that no suggestion respecting the causes of the transmutation assumed, which had been made, was in any way adequate to explain the phenomena. Looking back at the state of knowledge at that time, I really do not see that any other conclusion was justifiable. In those days I had never even heard of Treviranus' 'Biologie.' However, I had studied Lamarck attentively and I had read the 'Vestiges' with due care; but neither of them afforded me any good ground for changing my negative and critical attitude. As for the 'Vestiges,' I confess that the book simply irritated me by the prodigious ignorance and thoroughly unscientific habit of mind manifested by the writer. If it had any influence on me at all, it set me against Evolution; and the only review I ever have qualms of conscience about, on the ground of needless savagery, is one I wrote on the 'Vestiges' while under that influence. With respect to the 'Philosophie Zoologique,' it is no reproach to Lamarck to say that the discussion of the Species question in that work, whatever might be said for it in 1809, was miserably below the level of the knowledge of half a century later. In that interval of time the elucidation of the structure of the lower animals and plants had given rise to wholly new conceptions of their relations; histology and embryology, in the modern sense, had been created; physiology had been reconstituted; the facts of distribution, geological and geographical, had been prodigiously multiplied and reduced to order. To any biologist whose studies had carried him beyond mere species-mongering in 1850, one-half of Lamarck's arguments were obsolete and the other half erroneous, or defective, in virtue of omitting to deal with the various classes of evidence which had been brought to light since his time. Moreover his one suggestion as to the cause of the gradual modification of species--effort excited by change of conditions--was, on the face of it, inapplicable to the whole vegetable world. I do not think that any impartial judge who reads the 'Philosophie Zoologique' now, and who afterwards takes up Lyell's trenchant and effectual criticism (published as far back as 1830), will be disposed to allot to Lamarck a much higher place in the establishment of biological evolution than that which Bacon assigns to himself in relation to physical science generally,--buccinator tantum. (Erasmus Darwin first promulgated Lamarck's fundamental conceptions, and, with greater logical consistency, he had applied them to plants. But the advocates of his claims have failed to show that he, in any respect, anticipated the central idea of the 'Origin of Species.') But, by a curious irony of fate, the same influence which led me to put as little faith in modern speculations on this subject, as in the venerable traditions recorded in the first two chapters of Genesis, was perhaps more potent than any other in keeping alive a sort of pious conviction that Evolution, after all, would turn out true. I have recently read afresh the first edition of the 'Principles of Geology'; and when I consider that this remarkable book had been nearly thirty years in everybody's hands, and that it brings home to any reader of ordinary intelligence a great principle and a great fact--the principle, that the past must be explained by the present, unless good cause be shown to the contrary; and the fact, that, so far as our knowledge of the past history of life on our globe goes, no such cause can be shown (The same principle and the same fact guide the result from all sound historical investigation. Grote's 'History of Greece' is a product of the same intellectual movement as Lyell's 'Principles.')--I cannot but believe that Lyell, for others, as for myself, was the chief agent for smoothing the road for Darwin. For consistent uniformitarianism postulates evolution as much in the organic as in the inorganic world. The origin of a new species by other than ordinary agencies would be a vastly greater "catastrophe" than any of those which Lyell successfully eliminated from sober geological speculation. In fact, no one was better aware of this than Lyell himself. (Lyell, with perfect right, claims this position for himself. He speaks of having "advocated a law of continuity even in the organic world, so far as possible without adopting Lamarck's theory of transmutation"... "But while I taught that as often as certain forms of animals and plants disappeared, for reasons quite intelligible to us, others took their place by virtue of a causation which was beyond our comprehension; it remained for Darwin to accumulate proof that there is no break between the incoming and the outgoing species, that they are the work of evolution, and not of special creation... "I had certainly prepared the way in this country, in six editions of my work before the 'Vestiges of Creation' appeared in 1842 [1844], for the reception of Darwin's gradual and insensible evolution of species."--'Life and Letters,' Letter to Haeckel, volume ii. page 436. November 23, 1868.) If one reads any of the earlier editions of the 'Principles' carefully (especially by the light of the interesting series of letters recently published by Sir Charles Lyell's biographer), it is easy to see that, with all his energetic opposition to Lamarck, on the one hand, and to the ideal quasi-progressionism of Agassiz, on the other, Lyell, in his own mind, was strongly disposed to account for the origination of all past and present species of living things by natural causes. But he would have liked, at the same time, to keep the name of creation for a natural process which he imagined to be incomprehensible. In a letter addressed to Mantell (dated March 2, 1827), Lyell speaks of having just read Lamarck; he expresses his delight at Lamarck's theories, and his personal freedom from any objection based on theological grounds. And though he is evidently alarmed at the pithecoid origin of man involved in Lamarck's doctrine, he observes:-- "But, after all, what changes species may really undergo! How impossible will it be to distinguish and lay down a line, beyond which some of the so-called extinct species have never passed into recent ones." Again, the following remarkable passage occurs in the postscript of a letter addressed to Sir John Herschel in 1836:-- "In regard to the origination of new species, I am very glad to find that you think it probable that it may be carried on through the intervention of intermediate causes. I left this rather to be inferred, not thinking it worth while to offend a certain class of persons by embodying in words what would only be a speculation." (In the same sense, see the letter to Whewell, March 7, 1837, volume ii., page 5:-- "In regard to this last subject [the changes from one set of animal and vegetable species to another]...you remember what Herschel said in his letter to me. If I had stated as plainly as he has done the possibility of the introduction or origination of fresh species being a natural, in contradistinction to a miraculous process, I should have raised a host of prejudices against me, which are unfortunately opposed at every step to any philosopher who attempts to address the public on these mysterious subjects." See also letter to Sedgwick, January 12, 1838 ii. page 35.) He goes on to refer to the criticisms which have been directed against him on the ground that, by leaving species to be originated by miracle, he is inconsistent with his own doctrine of uniformitarianism; and he leaves it to be understood that he had not replied, on the ground of his general objection to controversy. Lyell's contemporaries were not without some inkling of his esoteric doctrine. Whewell's 'History of the Inductive Sciences,' whatever its philosophical value, is always worth reading and always interesting, if under no other aspect than that of an evidence of the speculative limits within which a highly-placed divine might, at that time, safely range at will. In the course of his discussion of uniformitarianism, the encyclopaedic Master of Trinity observes:-- "Mr. Lyell, indeed, has spoken of an hypothesis that 'the successive creation of species may constitute a regular part of the economy of nature,' but he has nowhere, I think, so described this process as to make it appear in what department of science we are to place the hypothesis. Are these new species created by the production, at long intervals, of an offspring different in species from the parents? Or are the species so created produced without parents? Are they gradually evolved from some embryo substance? Or do they suddenly start from the ground, as in the creation of the poet?... "Some selection of one of these forms of the hypothesis, rather than the others, with evidence for the selection, is requisite to entitle us to place it among the known causes of change, which in this chapter we are considering. The bare conviction that a creation of species has taken place, whether once or many times, so long as it is unconnected with our organical sciences, is a tenet of Natural Theology rather than of Physical Philosophy." (Whewell's 'History,' volume iii. page 639-640 (Edition 2, 1847.)) The earlier part of this criticism appears perfectly just and appropriate; but, from the concluding paragraph, Whewell evidently imagines that by "creation" Lyell means a preternatural intervention of the Deity; whereas the letter to Herschel shows that, in his own mind, Lyell meant natural causation; and I see no reason to doubt (The following passages in Lyell's letters appear to me decisive on this point:-- To Darwin, October 3, 1859 (ii, 325), on first reading the 'Origin.' "I have long seen most clearly that if any concession is made, all that you claim in your concluding pages will follow. "It is this which has made me so long hesitate, always feeling that the case of Man and his Races, and of other animals, and that of plants, is one and the same, and that if a vera causa be admitted for one instant, [instead] of a purely unknown and imaginary one, such as the word 'creation,' all the consequences must follow." To Darwin, March 15, 1863 (volume ii. page 365). "I remember that it was the conclusion he [Lamarck] came to about man that fortified me thirty years ago against the great impression which his arguments at first made on my mind, all the greater because Constant Prevost, a pupil of Cuvier's forty years ago, told me his conviction 'that Cuvier thought species not real, but that science could not advance without assuming that they were so.'" To Hooker, March 9, 1863 (volume ii. page 361), in reference to Darwin's feeling about the 'Antiquity of Man.' "He [Darwin] seems much disappointed that I do not go farther with him, or do not speak out more. I can only say that I have spoken out to the full extent of my present convictions, and even beyond my state of FEELING as to man's unbroken descent from the brutes, and I find I am half converting not a few who were in arms against Darwin, and are even now against Huxley." He speaks of having had to abandon "old and long cherished ideas, which constituted the charm to me of the theoretical part of the science in my earlier day, when I believed with Pascal in the theory, as Hallam terms it, of 'the arch-angel ruined.'" See the same sentiment in the letter to Darwin, March 11, 1863, page 363:-- "I think the old 'creation' is almost as much required as ever, but of course it takes a new form if Lamarck's views improved by yours are adopted.") that, if Sir Charles could have avoided the inevitable corollary of the pithecoid origin of man--for which, to the end of his life, he entertained a profound antipathy--he would have advocated the efficiency of causes now in operation to bring about the condition of the organic world, as stoutly as he championed that doctrine in reference to inorganic nature. The fact is, that a discerning eye might have seen that some form or other of the doctrine of transmutation was inevitable, from the time when the truth enunciated by William Smith that successive strata are characterised by different kinds of fossil remains, became a firmly established law of nature. No one has set forth the speculative consequences of this generalisation better than the historian of the 'Inductive Sciences':-- "But the study of geology opens to us the spectacle of many groups of species which have, in the course of the earth's history, succeeded each other at vast intervals of time; one set of animals and plants disappearing, as it would seem, from the face of our planet, and others, which did not before exist, becoming the only occupants of the globe. And the dilemma then presents itself to us anew:--either we must accept the doctrine of the transmutation of species, and must suppose that the organized species of one geological epoch were transmuted into those of another by some long-continued agency of natural causes; or else, we must believe in many successive acts of creation and extinction of species, out of the common course of nature; acts which, therefore, we may properly call miraculous." (Whewell's 'History of the Inductive Sciences.' Edition ii., 1847, volume iii. pages 624-625. See for the author's verdict, pages 638-39.) Dr. Whewell decides in favour of the latter conclusion. And if any one had plied him with the four questions which he puts to Lyell in the passage already cited, all that can be said now is that he would certainly have rejected the first. But would he really have had the courage to say that a Rhinoceros tichorhinus, for instance, "was produced without parents;" or was "evolved from some embryo substance;" or that it suddenly started from the ground like Milton's lion "pawing to get free his hinder parts." I permit myself to doubt whether even the Master of Trinity's well-tried courage--physical, intellectual, and moral--would have been equal to this feat. No doubt the sudden concurrence of half-a-ton of inorganic molecules into a live rhinoceros is conceivable, and therefore may be possible. But does such an event lie sufficiently within the bounds of probability to justify the belief in its occurrence on the strength of any attainable, or, indeed, imaginable, evidence? In view of the assertion (often repeated in the early days of the opposition to Darwin) that he had added nothing to Lamarck, it is very interesting to observe that the possibility of a fifth alternative, in addition to the four he has stated, has not dawned upon Dr. Whewell's mind. The suggestion that new species may result from the selective action of external conditions upon the variations from their specific type which individuals present--and which we call "spontaneous," because we are ignorant of their causation--is as wholly unknown to the historian of scientific ideas as it was to biological specialists before 1858. But that suggestion is the central idea of the 'Origin of Species,' and contains the quintessence of Darwinism. Thus, looking back into the past, it seems to me that my own position of critical expectancy was just and reasonable, and must have been taken up, on the same grounds, by many other persons. If Agassiz told me that the forms of life which had successively tenanted the globe were the incarnations of successive thoughts of the Deity; and that he had wiped out one set of these embodiments by an appalling geological catastrophe as soon as His ideas took a more advanced shape, I found myself not only unable to admit the accuracy of the deductions from the facts of paleontology, upon which this astounding hypothesis was founded, but I had to confess my want of any means of testing the correctness of his explanation of them. And besides that, I could by no means see what the explanation explained. Neither did it help me to be told by an eminent anatomist that species had succeeded one another in time, in virtue of "a continuously operative creational law." That seemed to me to be no more than saying that species had succeeded one another, in the form of a vote-catching resolution, with "law" to please the man of science, and "creational" to draw the orthodox. So I took refuge in that "thatige Skepsis" which Goethe has so well defined; and, reversing the apostolic precept to be all things to all men, I usually defended the tenability of the received doctrines, when I had to do with the transmutationists; and stood up for the possibility of transmutation among the orthodox--thereby, no doubt, increasing an already current, but quite undeserved, reputation for needless combativeness. I remember, in the course of my first interview with Mr. Darwin, expressing my belief in the sharpness of the lines of demarcation between natural groups and in the absence of transitional forms, with all the confidence of youth and imperfect knowledge. I was not aware, at that time, that he had then been many years brooding over the species-question; and the humorous smile which accompanied his gentle answer, that such was not altogether his view, long haunted and puzzled me. But it would seem that four or five years' hard work had enabled me to understand what it meant; for Lyell ('Life and Letters,' volume ii. page 212.), writing to Sir Charles Bunbury (under date of April 30, 1856), says:-- "When Huxley, Hooker, and Wollaston were at Darwin's last week they (all four of them) ran a tilt against species--further, I believe, than they are prepared to go." I recollect nothing of this beyond the fact of meeting Mr. Wollaston; and except for Sir Charles' distinct assurance as to "all four," I should have thought my "outrecuidance" was probably a counterblast to Wollaston's conservatism. With regard to Hooker, he was already, like Voltaire's Habbakuk, "capable du tout" in the way of advocating Evolution. As I have already said, I imagine that most of those of my contemporaries who thought seriously about the matter, were very much in my own state of mind--inclined to say to both Mosaists and Evolutionists, "a plague on both your houses!" and disposed to turn aside from an interminable and apparently fruitless discussion, to labour in the fertile fields of ascertainable fact. And I may, therefore, further suppose that the publication of the Darwin and Wallace papers in 1858, and still more that of the 'Origin' in 1859, had the effect upon them of the flash of light, which to a man who has lost himself in a dark night, suddenly reveals a road which, whether it takes him straight home or not, certainly goes his way. That which we were looking for, and could not find, was a hypothesis respecting the origin of known organic forms, which assumed the operation of no causes but such as could be proved to be actually at work. We wanted, not to pin our faith to that or any other speculation, but to get hold of clear and definite conceptions which could be brought face to face with facts and have their validity tested. The 'Origin' provided us with the working hypothesis we sought. Moreover, it did the immense service of freeing us for ever from the dilemma--refuse to accept the creation hypothesis, and what have you to propose that can be accepted by any cautious reasoner? In 1857, I had no answer ready, and I do not think that any one else had. A year later, we reproached ourselves with dullness for being perplexed by such an inquiry. My reflection, when I first made myself master of the central idea of the 'Origin,' was, "How extremely stupid not to have thought of that!" I suppose that Columbus' companions said much the same when he made the egg stand on end. The facts of variability, of the struggle for existence, of adaptation to conditions, were notorious enough; but none of us had suspected that the road to the heart of the species problem lay through them, until Darwin and Wallace dispelled the darkness, and the beacon-fire of the 'Origin' guided the benighted. Whether the particular shape which the doctrine of evolution, as applied to the organic world, took in Darwin's hands, would prove to be final or not, was, to me, a matter of indifference. In my earliest criticisms of the 'Origin' I ventured to point out that its logical foundation was insecure so long as experiments in selective breeding had not produced varieties which were more or less infertile; and that insecurity remains up to the present time. But, with any and every critical doubt which my sceptical ingenuity could suggest, the Darwinian hypothesis remained incomparably more probable than the creation hypothesis. And if we had none of us been able to discern the paramount significance of some of the most patent and notorious of natural facts, until they were, so to speak, thrust under our noses, what force remained in the dilemma--creation or nothing? It was obvious that, hereafter, the probability would be immensely greater, that the links of natural causation were hidden from our purblind eyes, than that natural causation should be incompetent to produce all the phenomena of nature. The only rational course for those who had no other object than the attainment of truth, was to accept "Darwinism" as a working hypothesis, and see what could be made of it. Either it would prove its capacity to elucidate the facts of organic life, or it would break down under the strain. This was surely the dictate of common sense; and, for once, common sense carried the day. The result has been that complete volte-face of the whole scientific world, which must seem so surprising to the present generation. I do not mean to say that all the leaders of biological science have avowed themselves Darwinians; but I do not think that there is a single zoologist, or botanist, or palaeontologist, among the multitude of active workers of this generation, who is other than an evolutionist, profoundly influenced by Darwin's views. Whatever may be the ultimate fate of the particular theory put forth by Darwin, I venture to affirm that, so far as my knowledge goes, all the ingenuity and all the learning of hostile critics have not enabled them to adduce a solitary fact, of which it can be said, this is irreconcilable with the Darwinian theory. In the prodigious variety and complexity of organic nature, there are multitudes of phenomena which are not deducible from any generalisations we have yet reached. But the same may be said of every other class of natural objects. I believe that astronomers cannot yet get the moon's motions into perfect accordance with the theory of gravitation. It would be inappropriate, even if it were possible, to discuss the difficulties and unresolved problems which have hitherto met the evolutionist, and which will probably continue to puzzle him for generations to come, in the course of this brief history of the reception of Mr. Darwin's great work. But there are two or three objections of a more general character, based, or supposed to be based, upon philosophical and theological foundations, which were loudly expressed in the early days of the Darwinian controversy, and which, though they have been answered over and over again, crop up now and then to the present day. The most singular of these, perhaps immortal, fallacies, which live on, Tithonus-like, when sense and force have long deserted them, is that which charges Mr. Darwin with having attempted to reinstate the old pagan goddess, Chance. It is said that he supposes variations to come about "by chance," and that the fittest survive the "chances" of the struggle for existence, and thus "chance" is substituted for providential design. It is not a little wonderful that such an accusation as this should be brought against a writer who has, over and over again, warned his readers that when he uses the word "spontaneous," he merely means that he is ignorant of the cause of that which is so termed; and whose whole theory crumbles to pieces if the uniformity and regularity of natural causation for illimitable past ages is denied. But probably the best answer to those who talk of Darwinism meaning the reign of "chance," is to ask them what they themselves understand by "chance"? Do they believe that anything in this universe happens without reason or without a cause? Do they really conceive that any event has no cause, and could not have been predicted by any one who had a sufficient insight into the order of Nature? If they do, it is they who are the inheritors of antique superstition and ignorance, and whose minds have never been illumined by a ray of scientific thought. The one act of faith in the convert to science, is the confession of the universality of order and of the absolute validity in all times and under all circumstances, of the law of causation. This confession is an act of faith, because, by the nature of the case, the truth of such propositions is not susceptible of proof. But such faith is not blind, but reasonable; because it is invariably confirmed by experience, and constitutes the sole trustworthy foundation for all action. If one of these people, in whom the chance-worship of our remoter ancestors thus strangely survives, should be within reach of the sea when a heavy gale is blowing, let him betake himself to the shore and watch the scene. Let him note the infinite variety of form and size of the tossing waves out at sea; or of the curves of their foam-crested breakers, as they dash against the rocks; let him listen to the roar and scream of the shingle as it is cast up and torn down the beach; or look at the flakes of foam as they drive hither and thither before the wind; or note the play of colours, which answers a gleam of sunshine as it falls upon the myriad bubbles. Surely here, if anywhere, he will say that chance is supreme, and bend the knee as one who has entered the very penetralia of his divinity. But the man of science knows that here, as everywhere, perfect order is manifested; that there is not a curve of the waves, not a note in the howling chorus, not a rainbow-glint on a bubble, which is other than a necessary consequence of the ascertained laws of nature; and that with a sufficient knowledge of the conditions, competent physico-mathematical skill could account for, and indeed predict, every one of these "chance" events. A second very common objection to Mr. Darwin's views was (and is), that they abolish Teleology, and eviscerate the argument from design. It is nearly twenty years since I ventured to offer some remarks on this subject, and as my arguments have as yet received no refutation, I hope I may be excused for reproducing them. I observed, "that the doctrine of Evolution is the most formidable opponent of all the commoner and coarser forms of Teleology. But perhaps the most remarkable service to the Philosophy of Biology rendered by Mr. Darwin is the reconciliation of Teleology and Morphology, and the explanation of the facts of both, which his views offer. The teleology which supposes that the eye, such as we see it in man, or one of the higher vertebrata, was made with the precise structure it exhibits, for the purpose of enabling the animal which possesses it to see, has undoubtedly received its death-blow. Nevertheless, it is necessary to remember that there is a wider teleology which is not touched by the doctrine of Evolution, but is actually based upon the fundamental proposition of Evolution. This proposition is that the whole world, living and not living, is the result of the mutual interaction, according to definite laws, of the forces (I should now like to substitute the word powers for "forces.") possessed by the molecules of which the primitive nebulosity of the universe was composed. If this be true, it is no less certain that the existing world lay potentially in the cosmic vapour, and that a sufficient intelligence could, from a knowledge of the properties of the molecules of that vapour, have predicted, say the state of the fauna of Britain in 1869, with as much certainty as one can say what will happen to the vapour of the breath on a cold winter's day... ...The teleological and the mechanical views of nature are not, necessarily, mutually exclusive. On the contrary, the more purely a mechanist the speculator is, the more firmly does he assume a primordial molecular arrangement of which all the phenomena of the universe are the consequences, and the more completely is he thereby at the mercy of the teleologist, who can always defy him to disprove that this primordial molecular arrangement was not intended to evolve the phenomena of the universe." (The "Genealogy of Animals" ('The Academy,' 1869), reprinted in 'Critiques and Addresses.') The acute champion of Teleology, Paley, saw no difficulty in admitting that the "production of things" may be the result of trains of mechanical dispositions fixed beforehand by intelligent appointment and kept in action by a power at the centre ('Natural Theology,' chapter xxiii.), that is to say, he proleptically accepted the modern doctrine of Evolution; and his successors might do well to follow their leader, or at any rate to attend to his weighty reasonings, before rushing into an antagonism which has no reasonable foundation. Having got rid of the belief in chance and the disbelief in design, as in no sense appurtenances of Evolution, the third libel upon that doctrine, that it is anti-theistic, might perhaps be left to shift for itself. But the persistence with which many people refuse to draw the plainest consequences from the propositions they profess to accept, renders it advisable to remark that the doctrine of Evolution is neither Anti-theistic nor Theistic. It simply has no more to do with Theism than the first book of Euclid has. It is quite certain that a normal fresh-laid egg contains neither cock nor hen; and it is also as certain as any proposition in physics or morals, that if such an egg is kept under proper conditions for three weeks, a cock or hen chicken will be found in it. It is also quite certain that if the shell were transparent we should be able to watch the formation of the young fowl, day by day, by a process of evolution, from a microscopic cellular germ to its full size and complication of structure. Therefore Evolution, in the strictest sense, is actually going on in this and analogous millions and millions of instances, wherever living creatures exist. Therefore, to borrow an argument from Butler, as that which now happens must be consistent with the attributes of the Deity, if such a Being exists, Evolution must be consistent with those attributes. And, if so, the evolution of the universe, which is neither more nor less explicable than that of a chicken, must also be consistent with them. The doctrine of Evolution, therefore, does not even come into contact with Theism, considered as a philosophical doctrine. That with which it does collide, and with which it is absolutely inconsistent, is the conception of creation, which theological speculators have based upon the history narrated in the opening of the book of Genesis. There is a great deal of talk and not a little lamentation about the so-called religious difficulties which physical science has created. In theological science, as a matter of fact, it has created none. Not a solitary problem presents itself to the philosophical Theist, at the present day, which has not existed from the time that philosophers began to think out the logical grounds and the logical consequences of Theism. All the real or imaginary perplexities which flow from the conception of the universe as a determinate mechanism, are equally involved in the assumption of an Eternal, Omnipotent and Omniscient Deity. The theological equivalent of the scientific conception of order is Providence; and the doctrine of determinism follows as surely from the attributes of foreknowledge assumed by the theologian, as from the universality of natural causation assumed by the man of science. The angels in 'Paradise Lost' would have found the task of enlightening Adam upon the mysteries of "Fate, Foreknowledge, and Free-will," not a whit more difficult, if their pupil had been educated in a "Real-schule" and trained in every laboratory of a modern university. In respect of the great problems of Philosophy, the post-Darwinian generation is, in one sense, exactly where the prae-Darwinian generations were. They remain insoluble. But the present generation has the advantage of being better provided with the means of freeing itself from the tyranny of certain sham solutions. The known is finite, the unknown infinite; intellectually we stand on an islet in the midst of an illimitable ocean of inexplicability. Our business in every generation is to reclaim a little more land, to add something to the extent and the solidity of our possessions. And even a cursory glance at the history of the biological sciences during the last quarter of a century is sufficient to justify the assertion, that the most potent instrument for the extension of the realm of natural knowledge which has come into men's hands, since the publication of Newton's 'Principia,' is Darwin's 'Origin of Species.' It was badly received by the generation to which it was first addressed, and the outpouring of angry nonsense to which it gave rise is sad to think upon. But the present generation will probably behave just as badly if another Darwin should arise, and inflict upon them that which the generality of mankind most hate--the necessity of revising their convictions. Let them, then, be charitable to us ancients; and if they behave no better than the men of my day to some new benefactor, let them recollect that, after all, our wrath did not come to much, and vented itself chiefly in the bad language of sanctimonious scolds. Let them as speedily perform a strategic right-about-face, and follow the truth wherever it leads. The opponents of the new truth will discover, as those of Darwin are doing, that, after all, theories do not alter facts, and that the universe remains unaffected even though texts crumble. Or, it may be, that, as history repeats itself, their happy ingenuity will also discover that the new wine is exactly of the same vintage as the old, and that (rightly viewed) the old bottles prove to have been expressly made for holding it. 
19192	----	public domain works from the University of Michigan Digital Libraries) WHAT IS DARWINISM? BY CHARLES HODGE, PRINCETON, N. J. NEW YORK: SCRIBNER, ARMSTRONG, AND COMPANY. 1874. Entered according to Act of Congress, in the year 1874, by SCRIBNER, ARMSTRONG, & COMPANY, In the Office of the Librarian of Congress, at Washington. RIVERSIDE, CAMBRIDGE: STEREOTYPED AND PRINTED BY H. O. HOUGHTON AND COMPANY. CONTENTS. PAGE IMPORTANCE OF THE QUESTION 1 DIFFERENT THEORIES AS TO THE ORIGIN OF THE UNIVERSE, AND SPECIALLY OF VEGETABLE AND ANIMAL ORGANISMS. 1. The Scriptural Theory 3 2. The Pantheistic Theory 7 3. The Epicurean Theory 10 4. The Doctrine of Herbert Spencer 11 5. Hylozoic Theory 21 6. Unscriptural Forms of Theism 22 DARWIN'S THEORY 26 NATURAL SELECTION 31 SENSE IN WHICH DARWIN USES THE WORD NATURAL 40 THE THREE ELEMENTS OR DARWINISM 48 THE EXCLUSION OF DESIGN IN NATURE THE FORMATIVE IDEA OF DARWIN'S THEORY 49 PROOF OF DARWIN'S DENIAL OF TELEOLOGY, FROM HIS OWN WRITINGS 53 PROOF FROM THE EXPOSITIONS OF HIS THEORY BY ITS AVOWED ADVOCATES. Mr. Russell Wallace 64 Professor Huxley 72 Dr. Büchner 84 Carl Vogt 85 Prof. Haeckel 87 Strauss 147 PROOF FROM THE OBJECTIONS URGED BY THE OPPONENTS OF MR. DARWIN'S THEORY. Duke of Argyll 96 Agassiz 101 Professor Janet 105 M. Flourens 108 Rev. Walter Mitchell 111 Principal Dawson 119 RELATION OF DARWINISM TO RELIGION 125 CAUSES OF THE ANTAGONISM BETWEEN SCIENCE AND RELIGION 126 THE EVOLUTION THEORY CONTRARY TO FACTS AND TO SCRIPTURE 141 SIR WILLIAM THOMSON ON TELEOLOGY 165 DR. ASA GRAY 174 DARWINISM TANTAMOUNT TO ATHEISM 177 WHAT IS DARWINISM? This is a question which needs an answer. Great confusion and diversity of opinion prevail as to the real views of the man whose writings have agitated the whole world, scientific and religious. If a man says he is a Darwinian, many understand him to avow himself virtually an atheist; while another understands him as saying that he adopts some harmless form of the doctrine of evolution. This is a great evil. It is obviously useless to discuss any theory until we are agreed as to what that theory is. The question, therefore, What is Darwinism? must take precedence of all discussion of its merits. The great fact of experience is that the universe exists. The great problem which has ever pressed upon the human mind is to account for its existence. What was its origin? To what causes are the changes we witness around us to be referred? As we are a part of the universe, these questions concern ourselves. What are the origin, nature, and destiny of man? Professor Huxley is right in saying, "The question of questions for mankind--the problem which underlies all others, and is more interesting than any other--is the ascertainment of the place which Man occupies in nature and of his relation to the universe of things. Whence our race has come, what are the limits of our power over nature, and of nature's power over us, to what goal are we tending, are the problems which present themselves anew and with undiminished interest to every man born into the world."[1] Mr. Darwin undertakes to answer these questions. He proposes a solution of the problem which thus deeply concerns every living man. Darwinism is, therefore, a theory of the universe, at least so far as the living organisms on this earth are concerned. This being the case, it may be well to state, in few words, the other prevalent theories on this great subject, that the points of agreement and of difference between them and the views of Mr. Darwin may be the more clearly seen. _The Scriptural Solution of the Problem of the Universe_. That solution is stated in words equally simple and sublime: "In the beginning God created the heavens and the earth." We have here, first, the idea of God. The word God has in the Bible a definite meaning. It does not stand for an abstraction, for mere force, for law or ordered sequence. God is a spirit, and as we are spirits, we know from consciousness that God is, (1.) A Substance; (2.) That He is a person; and, therefore, a self-conscious, intelligent, voluntary agent. He can say I; we can address Him as Thou; we can speak of Him as He or Him. This idea of God pervades the Scriptures. It lies at the foundation of natural religion. It is involved in our religious consciousness. It enters essentially into our sense of moral obligation. It is inscribed ineffaceably, in letters more or less legible, on the heart of every human being. The man who is trying to be an atheist is trying to free himself from the laws of his being. He might as well try to free himself from liability to hunger or thirst. The God of the Bible, then, is a Spirit, infinite, eternal, and unchangeable in his being, wisdom, power, holiness, goodness, and truth. As every theory must begin with some postulate, this is the grand postulate with which the Bible begins. This is the first point. The second point concerns the origin of the universe. It is not eternal either as to matter or form. It is not independent of God. It is not an evolution of his being, or his existence form. He is extramundane as well as antemundane. The universe owes its existence to his will. Thirdly, as to the nature of the universe; it is not a mere phenomenon. It is an entity, having real objective existence, or actuality. This implies that matter is a substance endowed with certain properties, in virtue of which it is capable of acting and of being acted upon. These properties being uniform and constant, are physical laws to which, as their proximate causes, all the phenomena of nature are to be referred. Fourthly, although God is extramundane, He is nevertheless everywhere present. That presence is not only a presence of essence, but also of knowledge and power. He upholds all things. He controls all physical causes, working through them, with them, and without them, as He sees fit. As we, in our limited spheres, can use physical causes to accomplish our purposes, so God everywhere and always coöperates with them to accomplish his infinitely wise and merciful designs. Fifthly, man a part of the universe, is, according to the Scriptures, as concerns his body, of the earth. So far, he belongs to the animal kingdom. As to his soul, he is a child of God, who is declared to be the Father of the spirits of all men. God is a spirit, and we are spirits. We are, therefore, of the same nature with God. We are God-like; so that in knowing ourselves we know God. No man conscious of his manhood can be ignorant of his relationship to God as his Father. The truth of this theory of the universe rests, in the first place, so far as it has been correctly stated, on the infallible authority of the Word of God. In the second place, it is a satisfactory solution of the problem to be solved,--(1.) It accounts for the origin of the universe. (2.) It accounts for all the universe contains, and gives a satisfactory explanation of the marvellous contrivances which abound in living organisms, of the adaptations of these organisms to conditions external to themselves, and for those provisions for the future, which on any other assumption are utterly inexplicable. (3.) It is in conflict with no truth of reason and with no fact of experience.[2] (4.) The Scriptural doctrine accounts for the spiritual nature of man, and meets all his spiritual necessities. It gives him an object of adoration, love, and confidence. It reveals the Being on whom his indestructible sense of responsibility terminates. The truth of this doctrine, therefore, rests not only on the authority of the Scriptures, but on the very constitution of our nature. The Bible has little charity for those who reject it. It pronounces them to be either derationalized or demoralized, or both. FOOTNOTES: [1] _Evidences of Man's Place in Nature._ London, 1864, p. 57. [2] The two facts which are commonly urged as inconsistent with Theism, are the existence of misery in the world, and the occurrence of undeveloped or useless organs, as teeth in the jaws of the whale and mammæ on the breast of a man. As to the former objection, sin, which is the only real evil, is accounted for by the voluntary apostasy of man; and as to undeveloped organs they are regarded as evidences of the great plan of structure which can be traced in the different orders of animals. These unused organs were--says Professor Joseph Le Conte, in his interesting volume on Religion and Science, New York, 1874, p. 54--regarded as blunders in nature, until it was discovered that use is not the only end of design. "By further patient study of nature," he says, "came the recognition of another law beside use,--a law of order underlying and conditioning the law of use. Organisms are, indeed, contrived for use, but according to a preordained plan of structure, which must not be violated." It is of little moment whether this explanation be considered satisfactory or not. It would certainly be irrational to refuse to believe that the eye was made for the purpose of vision, because we cannot tell why a man has mammæ. A man might as well refuse to admit that there is any meaning in all the writings of Plato, because there is a sentence in them which he cannot understand. _The Pantheistic Theory_. This has been one of the most widely diffused and persistent forms of human thought on this whole subject. It has been for thousands of years not only the philosophy, but the religion of India, and, to a great extent, of China. It underlies all the forms of Greek philosophy. It crept into the Church, concealed under the disguise of Scriptural terminology, in the form of Neo-Platonism. It was constantly reappearing during the Middle Ages, sometimes in a philosophical, and sometimes a mystical form. It was revived by Spinoza in the seventeenth century, and subsequently became dominant in the philosophy and literature of Europe. It is coming up again. Some distinguished naturalists are swinging round from one pole to the opposite; from saying there is no God, to teaching that everything is God. Sometimes, one and the same book in one half teaches materialism, in the other half idealism: the one affirming that everything is matter, the other that matter is nothing, but that everything is mind, and mind is God. The leading principles of the Pantheistic theory are,--(1.) That there is an Infinite and Absolute Being. Of this Being nothing can be affirmed but actuality. It is denied that it is conscious, intelligent, or voluntary. (2.) It is subject to the blind necessity of self-evolution or development. (3.) This development being necessary is constant; from everlasting to everlasting. According to the Braminical doctrine, indeed, there are successive cycles of activity and repose, each cycle being measured by countless milliards of centuries. According to the moderns, self-evolution being necessary, there can be no repose, so that Ohne Welt kein Gott. (4.) The Finite is, therefore, the existence form of the Infinite; all that is in the latter for the time being is in the former. All that is possible is actual. (5.) The Finite is the Infinite, or, to use theistic language, the World is God, in the sense that all the world is and contains is the form in which God, at each successive moment, exists. There is no power, save only the power manifested in the world; no consciousness, intelligence, or voluntary activity, but in finite things, and the aggregate of these is the power, consciousness, intelligence, and activity of God. What we call sin is as much a form of God's activity as what we call virtue. In other words, there is no such thing as free agency in man, no such thing as sin or responsibility. When a man dies he sinks into the abyss of being as a drop of water is lost in the ocean. (6.) Man is the highest form of God's existence. God is incarnate in the human race. Strauss says, that what the Church teaches of Christ is not true of any individual man, but is true of mankind. Or, as Feuerbach more concisely expresses it, "Man alone is our God." The blasphemy of some of the German philosophers on this subject is simply unutterable. In India we see the practical operation of this system when it takes hold on the people. There the personification of the Infinite as evil (the Goddess Kala) is the most popular object of worship. _Epicurean Theory._ Epicurus assumed the existence of matter, force and motion,--Stoff und Kraft. He held that all space was filled with molecules of matter in a state of rapid motion in every direction. These molecules were subject to gravity and endowed with properties or forces. One combination of molecules gave rise to unorganized matter, another to life, another to mind; and from the various combinations, guided by unintelligent physical laws, all the wonderful organisms of plants and animals have arisen. To these combinations also all the phenomena of life, instinct, and intelligence in the world are to be referred. This theory has been adopted in our day by a large class of scientific men, especially in Germany. The modern advocates of the theory are immeasurably superior to the ancient Epicureans in their knowledge of astronomy, botany, zoölogy, and biology; but in their theory of the universe, and in their mode of accounting for all the phenomena of life and intelligence, they are precisely on the same level. They have not added an idea to the system, which has ever been regarded as the opprobrium of human thought. Büchner, Moleschott, Vogt, hold that matter is eternal and indestructible; that matter and force are inseparable: the one cannot exist without the other. What, it is asked, is motion without something moving? What is electricity without an electrified body? What is attraction without molecules attracting each other? What is contractibility without muscular fibre, or secretion without a secreting gland? One combination of molecules exhibits the phenomena of life, another combination exhibits the phenomena of mind. All this was taught by the old heathen philosopher more than two thousand years ago. That this system denies the existence of God, of mind as a thinking substance distinct from matter, and of the possibility of the conscious existence of man after death, are not inferences drawn by opponents, but conclusions openly avowed by its advocates. _Herbert Spencer's New Philosophy._ Mr. Darwin calls Spencer our "great philosopher." His is the speculating mind of the new school of science. This gives to his opinions special interest, although no one but himself is to be held responsible for his peculiar views, except so far as others see fit to avow them. Mr. Spencer postulates neither mind nor matter. He begins with Force. Force, however, is itself perfectly inscrutable. All we know about it is, that it is, that it is indestructible, and that it is persistent. As to the origin of the universe, he says there are three possible suppositions: 1st. That it is self-existent. 2d. That it is self-created. 3d. That it is created by an external agency.[3] All these he examines and rejects. The first is equivalent to Atheism, by which Spencer understands the doctrine which makes Space, Matter, and Force eternal and the causes of all phenomena. This, he says, assumes the idea of self-existence, which is unthinkable. The second theory he makes equivalent to Pantheism. "The precipitation of vapor," he says, "into cloud, aids us in forming a symbolic conception of a self-evolved universe;" but, he adds, "really to conceive self-creation, is to conceive potential existence passing into actual existence by some inherent necessity, which we cannot do." (p. 32). The Theistic theory, he says, is equally untenable. "Whoever agrees that the atheistic hypothesis is untenable because it involves the impossible idea of self-existence, must perforce admit that the theistic hypothesis is untenable if it contains the same impossible idea." (p. 38). The origin of the universe is, therefore, a fact which cannot be explained. It must have had a cause; and all we know is that its cause is unknowable and inscrutable. When we turn to nature the result is the same. Everything is inscrutable. All we know is that there are certain appearances, and that where there is appearance there must be something that appears. But what that something is, what is the noumenon which underlies the phenomenon, it is impossible for us to know. In nature we find two orders of phenomena, or appearances; the one objective or external, the other subjective in our consciousness. There are an Ego and a non-Ego, a subject and object. These are not identical. "It is," he says, "rigorously impossible to conceive that our knowledge is a knowledge of appearances only, without at the same time conceiving a reality of which they are appearances, for appearance without reality is unthinkable." (p. 88). So far we can go. There is a reality which is the cause of phenomena. Further than that, in that direction, our ignorance is profound. He proves that space cannot be an entity, an attribute, or a category of thought, or a nonentity. The same is true of time, of motion, of matter, of electricity, light, magnetism, etc., etc. They all resolve themselves into appearances produced by an unknown cause. As the question, What is matter? is a crucial one, he dwells upon it in various parts of his writings. Newton's theory of ultimate atoms; Leibnitz's doctrine of monads; and the dynamic theory of Boscovich, which makes matter mere centres of force, are all dismissed as unthinkable. It is not very clear in what sense that word is to be taken. Sometimes it seems to mean, meaningless; at others, self-contradictory or absurd; at others, inconceivable, _i. e._ that of which no conception or mental image can be formed; at any rate, it implies what is unknowable and untenable. The result is, so far as matter is concerned, that we know nothing about it. "Our conception of matter," he says, "reduced to its simplest shape, is that of coexistent positions that offer resistance, as contrasted with our conception of space in which the coexistent positions offer no resistance." (p. 166). Resistance, however, is a form of force; and, therefore, on the following page, Spencer says, "that forces standing in certain correlations, form the whole contents of our idea of matter." When we turn from the objective to the subjective, from the external to the inward world, the result is still the same. He agrees with Hume in saying that the contents of our consciousness is a series of impressions and ideas. He dissents, however, from that philosopher, in saying that that series is all we know. He admits that impressions necessarily imply that there is something that is impressed. He starts the question, What is it that thinks? and answers, We do not know. (p. 63). He admits that the reality of individual personal minds, the conviction of personal existence is universal, and perhaps indestructible. Nevertheless that conviction cannot justify itself at the bar of reason; nay, reason is found to reject it. (p. 65). Dean Mansel says, that consciousness gives us a knowledge of self as a substance and not merely of its varying states. This, however, he says, "is absolutely negatived by the laws of thought. The fundamental condition to all consciousness, emphatically insisted upon by Mr. Mansel in common with Sir William Hamilton and others, is the antithesis of subject and object.... What is the corollary from this doctrine, as bearing on the consciousness of self? The mental act in which self is known implies, like every other mental act, a perceiving subject and a perceived object. If, then, the object perceived is self, what is the subject that perceives? Or if it is the true self which thinks, what other self can it be that is thought of? Clearly, a true cognition of self implies a state in which the knowing and the known are one--in which subject and object are identified; and this Mr. Mansel rightly holds to be the annihilation of both. So that the personality of which each is conscious, and of which the existence is to each a fact beyond all others the most certain, is yet a thing which cannot be known at all; knowledge of it is forbidden by the very nature of human thought." (pp. 65, 66). Mr. Spencer does not seem to expect that any man will be shaken in his conviction by any such argument as that. When a man is conscious of pain, he is not to be puzzled by telling him that the pain is one thing (the object perceived) and the self another thing (the perceiving subject). He knows that the pain is a state of the self of which he is conscious. Consciousness is a form of knowledge; but knowledge of necessity supposes an intelligent reality which knows. A philosophy which cannot be received until men cease to believe in their own existence, must be in extremis. Mr. Spencer's conclusion is, that the universe--nature, or the external world with all its marvels and perpetual changes,--the world of consciousness with its ever varying states, are impressions or phenomena, due to an inscrutable, persistent force. As to the nature of this primal force or power, he quotes abundantly and approvingly from Sir William Hamilton and Mr. Mansel, to prove that it is unknowable, inconceivable, unthinkable. He, however, differs from those distinguished writers in two points. While admitting that we know no more of the first cause than we do of a geometrical figure which is at once a circle and a square, yet we do know that it is actual. For this conviction we are not dependent on faith. In the second place, Hamilton and Mansel taught that we know that the Infinite cannot be a person, self-conscious, intelligent, and voluntary; yet we are forced by our moral constitution to believe it to be an intelligent person. This Mr. Spencer denies. "Let those," he says, "who can, believe that there is eternal war between our intellectual faculties and our moral obligations. I, for one, admit of no such radical vice in the constitution of things." (p. 108). Religion has always erred, he asserts, in that while it teaches that the Infinite Being cannot be known, it insists on ascribing to it such and such attributes, which of course assumes that so far forth it is known. We have no right, he contends, to ascribe personality to the "Unknown Reality," or anything else, except that it is the cause of all that we perceive or experience. There may be a mode of being, as much transcending intelligence and will, as these transcend mechanical motion. To show the folly of referring to the Unknown the attributes of our own spirits, he makes "the grotesque supposition that the tickings and other movements of a watch constituted a kind of consciousness; and that a watch possessed of such a consciousness, insisted on regarding the watchmaker's actions as determined like its own by springs and escapements." (p. 111). The vast majority of men, instead of agreeing with Mr. Spencer in this matter, will doubtless heartily, each for himself, join the German philosopher Jacobi, in saying, "I confess to Anthropomorphism inseparable from the conviction that man bears the image of God; and maintain that besides this Anthropomorphism, which has always been called Theism, is nothing but Atheism or Fetichism."[4] Mr. Spencer, therefore, in accounting for the origin of the universe and all its phenomena, physical, vital, and mental, rejects Theism, or the doctrine of a personal God, who is extramundane as well as antemundane, the creator and governor of all things; he rejects Pantheism, which makes the finite the existence-form of the Infinite; he rejects Atheism, which he understands to be the doctrine of the eternity and self-existence of matter and force. He contents himself with saying we must acknowledge the reality of an unknown something which is the cause of all things,--the noumenon of all phenomena. "If science and religion are to be reconciled, the basis of the reconciliation must be this deepest, widest, and most certain of all facts,--that the Power which the universe manifests is utterly inscrutable." (p. 46). "The ultimate of ultimates is Force." "Matter and motion, as we know them, are differently conditioned manifestations of force." "If, to use an algebraic illustration, we represent Matter, Motion, and Force, by the symbols _x_, _y_, _z_; then we may ascertain the values of _x_ and _y_ in terms of _z_, but the value of _z_ can never be found; _z_ is the unknown quantity, which must forever remain unknown, for the obvious reason that there is nothing in which its value can be expressed." (pp. 169, 170). We have, then, no God but Force. Atheist is everywhere regarded as a term of reproach. Every man instinctively recoils from it. Even the philosophers of the time of the French Revolution repudiated the charge of atheism, because they believed in motion; and motion being inscrutable, they believed in an inscrutable something, _i. e._ in Force. We doubt not Mr. Spencer would indignantly reject the imputation of atheism; nevertheless, in the judgment of most men, the difference between Antitheist and Atheist is a mere matter of orthography. FOOTNOTES: [3] _First Principles of a New System of Philosophy._ By Herbert Spencer. Second edition. New York, 1869, p. 30. [4] _Von den göttlichen Dingen_, _Werke_, III. pp. 422, 425. Leipzig, 1816. _Hylozoic Theory._ This theory assumes the universe to be eternal. There is nothing extra, or antemundane. There is but one substance, and that substance is matter. Matter, however, has an active and passive principle. Life and rationality are among its attributes or functions. The universe, therefore, is a living whole pervaded by a principle not only of life but of intelligence. This hylozoic doctrine, some modern scientific men, as Professor Tyndall, seem inclined to adopt. They tell us that matter is not the dead and degraded thing it is commonly regarded. It is active and transcendental. What that means, we do not know. The word transcendental is like a parabola, in that there is no knowing where its meaning ends. To say that matter is transcendental, is saying there is no telling what it is up to. This habit of using words which have no definite meaning is very convenient to writers, but very much the reverse for readers. Some of the ancient Stoics distinguished between the active and passive principles in the world, calling the one mind, the other, matter. These however were as intimately united as matter and life in a plant or animal. _Theism in Unscriptural Forms._ There are men who are constrained to admit the being of God, who depart from the Scriptural doctrine as to his relation to the world. According to some, God created matter and endowed it with certain properties, and then left it to itself to work out, without any interference or control on his part, all possible results. According to others, He created not only matter, but life, or living germs, one or more, from which without any divine intervention all living organisms have been developed. Others, again, refer not only matter and life, but mind also to the act of the Creator; but with creation his agency ceases. He has no more to do with the world, than a ship-builder has with the ship he has constructed, when it is launched and far off upon the ocean. According to all these views a creator is a mere _Deus ex machina_, an assumption to account for the origin of the universe. Another general view of God's relation to the world goes to the opposite extreme. Instead of God doing nothing, He does everything. Second causes have no efficiency. The laws of nature are said to be the uniform modes of divine operation. Gravitation does not flow from the nature of matter, but is a mode of God's uniform efficiency. What are called chemical affinities are not due to anything in different kinds of matter, but God always acts in one way in connection with an acid, and in another way in connection with an alkali. If a man places a particle of salt or sugar on his tongue, the sensation which he experiences is not to be referred to the salt or sugar, but to God's agency. When this theory is extended, as it generally is by its advocates, from the external to the internal world, the universe of matter and mind, with all their phenomena, is a constant effect of the omnipresent activity of God. The minds of some men, as remarked above, are so constituted that they can pass from the theory that God does nothing, to the doctrine that He does everything, without seeing the difference. Mr. Russel Wallace, the companion and peer of Mr. Darwin, devotes a large part of his book on "Natural Selection," to prove that the organs of plants and animals are formed by blind physical causes. Toward the close of the volume he teaches that there are no such causes. He asks the question, What is Matter? and answers, Nothing. We know, he says, nothing but force; and as the only force of which we have any immediate knowledge is mind-force, the inference is "that the whole universe is not merely dependent on, but actually _is_, the will of higher intelligences, or of one Supreme Intelligence."[5] This is a transition from virtual materialism to idealistic pantheism. The effect of this admission on the part of Mr. Wallace on the theory of natural selection, is what an explosion of its boiler would be to a steamer in mid-ocean, which should blow out its deck, sides, and bottom. Nothing would remain above water. The Duke of Argyll seems at times inclined to lapse into the same doctrine. "Science," he says, "in the modern doctrine of conservation of energy and the convertibility of forces, is already getting a firm hold of the idea, that all kinds of force are but forms of manifestations of one central force issuing from some one fountain-head of power. Sir John Herschel has not hesitated to say, 'that it is but reasonable to regard the force of gravitation as the direct or indirect result of a consciousness or will existing somewhere.' And even if we cannot certainly identify force in all its forms with the direct energies of the one Omnipresent and All-pervading Will, it is at least in the highest degree unphilosophical to assert the contrary,--to think or to speak, as if the forces of nature were either independent of, or even separate from the Creator's power."[6] The Duke, however, in the general tenor of his book, does not differ from the common doctrine, except in one point. He does not deny the efficiency of physical causes, or resolve them all into the efficiency of God; but he teaches that God, in this world at least, never acts except through those causes. He applies this doctrine even to miracles, which he regards as effects produced by second causes of which we are ignorant, that is, by some higher law of nature. The Scriptures, however, teach that God is not thus bound; that He operates through second causes, with them, or without them, as He sees fit. It is a purely arbitrary assumption, that when Christ raised the dead, healed the lepers, or gave sight to the blind, any second cause intervened between the effect and the efficiency of his will. What physical law, or uniformly acting force, operated to make the axe float at the command of the prophet? or, in that greatest of all miracles, the original creation of the world. FOOTNOTES: [5] _The Theory of Natural Selection._ By Alfred Russel Wallace. London, 1870, p. 368. [6] _Reign of Law._ By the Duke of Argyle. Fifth edition, London, 1867, p. 123. _Mr. Darwin's Theory._ We have not forgotten Mr. Darwin. It seemed desirable, in order to understand his theory, to see its relation to other theories of the universe and its phenomena, with which it is more or less connected. His work on the "Origin of Species" does not purport to be philosophical. In this aspect it is very different from the cognate works of Mr. Spencer. Darwin does not speculate on the origin of the universe, on the nature of matter, or of force. He is simply a naturalist, a careful and laborious observer; skillful in his descriptions, and singularly candid in dealing with the difficulties in the way of his peculiar doctrine. He set before himself a single problem, namely, How are the fauna and flora of our earth to be accounted for? In the solution of this problem, he assumes:-- 1. The existence of matter, although he says little on the subject. Its existence however, as a real entity, is everywhere taken for granted. 2. He assumes the efficiency of physical causes, showing no disposition to resolve them into mind-force, or into the efficiency of the First Cause. 3. He assumes also the existence of life in the form of one or more primordial germs. He does not adopt the theory of spontaneous generation. What life is he does not attempt to explain, further than to quote (p. 326), with approbation, the definition of Herbert Spencer, who says, "Life depends on, or consists in, the incessant action and reaction of various forces,"--which conveys no very definite idea. 4. To account for the existence of matter and life, Mr. Darwin admits a Creator. This is done explicitly and repeatedly. Nothing, however, is said of the nature of the Creator and of his relation to the world, further than is implied in the meaning of the word. 5. From the primordial germ or germs (Mr. Darwin seems to have settled down to the assumption of only one primordial germ), all living organisms, vegetable and animal, including man, on our globe, through all the stages of its history, have descended. 6. As growth, organization, and reproduction are the functions of physical life, as soon as the primordial germ began to live, it began to grow, to fashion organs however simple, for its nourishment and increase, and for the reproduction, in some way, of living forms like itself. How all living things on earth, including the endless variety of plants, and all the diversity of animals--insects, fishes, birds, the ichthyosaurus, the mastodon, the mammoth, and man--have descended from the primordial animalcule, he thinks, may be accounted for by the operation of the following natural laws, viz.:-- First, the law of Heredity, or that by which like begets like. The offspring are like the parent. Second, the law of Variation, that is, while the offspring are, in all essential characteristics, like their immediate progenitor, they nevertheless vary more or less within narrow limits, from their parent and from each other. Some of these variations are indifferent, some deteriorations, some improvements, that is, they are such as enable the plant or animal to exercise its functions to greater advantage. Third, the law of Over Production. All plants and animals tend to increase in a geometrical ratio; and therefore tend to overrun enormously the means of support. If all the seeds of a plant, all the spawn of a fish, were to arrive at maturity, in a very short time the world could not contain them. Hence of necessity arises a struggle for life. Only a few of the myriads born can possibly live. Fourth, here comes in the law of Natural Selection, or the Survival of the Fittest. That is, if any individual of a given species of plant or animal happens to have a slight deviation from the normal type, favorable to its success in the struggle for life, it will survive. This variation, by the law of heredity, will be transmitted to its offspring, and by them again to theirs. Soon these favored ones gain the ascendency, and the less favored perish; and the modification becomes established in the species. After a time another and another of such favorable variations occur, with like results. Thus very gradually, great changes of structure are introduced, and not only species, but genera, families, and orders in the vegetable and animal world, are produced. Mr. Darwin says he can set no limit to the changes of structure, habits, instincts, and intelligence, which these simple laws in the course of millions or milliards of centuries may bring into existence. He says, "we cannot comprehend what the figures 60,000,000 really imply, and during this, or perhaps a longer roll of years, the land and waters have everywhere teemed with living creatures, all exposed to the struggle for life, and undergoing change." (p. 354). "Mr. Croll," he tells us, "estimates that about sixty millions of years have elapsed since the Cambrian period, but this, judging from the small amount of organic change since the commencement of the glacial period, seems a very short time for the many and the great mutations of life, which have certainly occurred since the Cambrian formation; and the previous one hundred and forty million years can hardly be considered as sufficient for the development of the varied forms of life which certainly existed toward the close of the Cambrian period." (p. 379). Years in this connection have no meaning. We might as well try to give the distance of the fixed stars in inches. As astronomers are obliged to take the diameter of the earth's orbit as the unit of space, so Darwinians are obliged to take a geological cycle as their unit of duration. _Natural Selection._ As Natural Selection which works so slowly is a main element in Mr. Darwin's theory, it is necessary to understand distinctly what he means by it. On this point he leaves us no room for doubt. On p. 92, he says: "This preservation of favorable variations, and the destruction of injurious variations, I call Natural Selection, or, the Survival of the Fittest." "Owing to the struggle (for life) variations, however slight and from whatever cause proceeding, if they be in any degree profitable to the individuals of a species, in their infinitely complex relations to other organic beings and to their physical conditions of life, will tend to the preservation of such individuals, and will generally be inherited by their offspring. The offspring also will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection, in order to mark its relation to man's power of selection. But the expression often used by Mr. Herbert Spencer of the Survival of the Fittest, is more accurate, and sometimes is equally convenient." (p. 72). "Slow though the progress of selection may be, if feeble man can do so much by artificial selection, I can see no limit to the amount of change, to the beauty and infinite complexity of the co-adaptations between all organic beings, one with another, and with their physical conditions of life, which may be effected in the long course of time by nature's power of selection, or the survival of the fittest." (p. 125). "It may be objected that if organic beings thus tend to rise in the scale, how is it that throughout the world a multitude of the lowest forms still exist; and how is it that in each great class some forms are far more highly developed than others?... On our theory the continuous existence of lowly forms offers no difficulty; for natural selection, or the survival of the fittest, does not necessarily include progressive development, it only takes advantage of such variations as arise and are beneficial to each creature under its complex relations of life.... Geology tells us that some of the lowest forms, the infusoria and rhizopods, have remained for an enormous period in nearly their present state." (p. 145). "The fact of little or no modification having been effected since the glacial period would be of some avail against those who believe in an innate and necessary law of development, but is powerless against the doctrine of natural selection, or the survival of the fittest, which implies only that variations or individual differences of a favorable nature occasionally arise in a few species and are then preserved." (p. 149) This process of improvement under the law of natural selection includes not only changes in the organic structure of animals, but also in their instincts and intelligence. On entering on this part of his subject, Mr. Darwin says, "I would premise that I have nothing to do with the origin of the primary mental powers, any more than I have with that of life itself. We are concerned only with the diversities of instinct and of other mental qualities within the same class." (p. 255) He shows that even in a state of nature the instincts of animals of the same species do in some degree vary, and that they are transmitted by inheritance. A mastiff has imparted courage to a greyhound, and a greyhound has transmitted to a shepherd-dog a disposition to hunt hares. Among sporting dogs, the young of the pointer or retriever have been known to point or to retrieve without instruction. "If," he says, "it can be shown that instincts do vary ever so little, then I can see no difficulty in natural selection preserving and continually accumulating variations of instinct to any extent that was profitable. It is thus, as I believe, that all the most complex and wonderful instincts have arisen." (p. 257) He was rather unguarded in saying that he saw no difficulty in accounting for the most wonderful instincts of animals. He admits that he has found very great difficulty. He selects three cases which he found it specially hard to deal with: that of the cuckoo, that of the cell-building bee, and of the slave-making ant. He devotes much space and labor in endeavoring to show how the instinct of the bee, for example, in the construction of its cell, _might_ have been gradually acquired. It is clear, however, that he was not able fully to satisfy even his own mind; for he admits that "it will be thought that I have an over-weening confidence in the principle of natural selection, when I do not admit that such wonderful and well established facts do not annihilate the theory." (p. 290) This remark was made with special reference to the instincts of the ant, which he finds very hard to account for. He adds, "No doubt many instincts of very difficult explanation could be opposed to the theory of natural selection: cases in which we cannot see how an instinct could possibly have originated; cases in which no intermediate gradations are known to exist; cases of instinct of such trifling importance that they could hardly have been acted upon by natural selection; cases of instincts almost identically the same in animals so remote in the scale of nature, that we cannot account for their similarity by inheritance from a common progenitor, and consequently cannot believe that they were independently acquired through natural selection. I will not here enter on those cases, but will confine myself to one special difficulty which at first appeared to me insuperable, and actually fatal to the whole theory. I allude to neuters, or sterile females in insect communities; for these neuters often differ widely in instinct and structure from both the males and the fertile females, and yet, from being sterile, they cannot propagate their kind." (p. 289) He is candid enough to say, in conclusion, "I do not pretend that the facts given in this chapter (on instinct) strengthen in any great degree my theory; but none of the cases of difficulty, to the best of my judgment, annihilate it." (p. 297) When it is remembered that his theory is, that slight variations occurring in an individual advantageous to it (not to its associates), in the struggle for life, is perpetuated by inheritance, it is no wonder that the case of sterile ants gave him so much trouble. Accidental sterility is not favorable to the individual, and its being made permanent by inheritance, is out of the question, for the sterile have no descendants. Yet these sterile females are not degenerations, they are in general larger and more robust than their associates. We have thus seen that, according to Mr. Darwin, all the infinite variety of structure in plants and animals is due to the law of natural selection. "On the principle of natural selection with divergence of character," he says, "it does not seem incredible that, from some such low and intermediate form, both animals and plants have been developed, and if we admit this, we must likewise admit that all the organized beings which have ever lived on this earth may be descended from some one primordial form." (p. 573) We have seen also that he does not confine his theory to organic structure, but applies it to all the instincts and all the forms of intelligence manifested by irrational creatures. Nor does he stop there; he includes man within the sweep of the same law. "In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the _necessary_ acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history." (p. 577) The "distant future" was near at hand. In his introduction to his work on the "Descent of Man," he says, he had determined not to publish on that subject, "as I thought that I should thus only add to the prejudices against my views. It seemed to me sufficient to indicate, in the first edition of my 'Origin of Species,' that by this work 'light would be thrown on the origin of man and his history;' and this implies that man must be included with other organic beings in any general conclusion respecting his manner of appearance on this earth. Now the case wears a wholly different aspect. When a naturalist like Carl Vogt (we shall see in what follows what kind of a witness he is) ventures to say in his address as President of the National Institution of Geneva (1869), 'Personne, en Europe au moins, n'ose plus soutenir la création indépendante et de toutes piéces, des espéces,'--it is manifest that at least a large number of naturalists must admit that species are the modified descendants of other species; and this especially holds good of the younger and rising naturalists.... Of the older and honored chiefs in natural science, many unfortunately are still opposed to evolution in every form." Carl Vogt would not write thus. To him no man is honored who does agree with him, and any man who believes in God he execrates. In 1871, Mr. Darwin ventured on the publication of his "Descent of Man." In that work, he endeavors to show that the proximate progenitor of man is the ape. He says "there is less difference of structure between the two, than between the higher and lower forms of apes themselves." Not only so, but he attempts to show that the mental faculties of man are derived by slight variations, long continued, from the measure of intellect possessed by lower animals. He even says, that there is less difference in intelligence between man and the higher mammals, than there is between the intelligence of the ant and that of the coccus, insects of the same class.[7] In like manner he teaches that man's moral nature has been evolved by slow degrees from the social instincts common to many animals. (pp. 68, 94) The moral element, thus derived, he admits might lead to very different lines of conduct. "If men," he says, "were reared under the same conditions as hives-bees, there can hardly be a doubt, that our unmarried females would, like the worker-bees, think it a sacred duty to kill all their brothers, and mothers would strive to kill their fertile daughters; and no one would think of interfering. (vol. i. p. 70) "Lower animals, especially the dog, manifest love, reverence, fidelity, and obedience; and it is from these elements that the religious sentiment in man has been slowly evolved by a process of natural selection." (vol. i. p. 65) The grand conclusion is, "man (body, soul, and spirit) is descended from a hairy quadruped, furnished with a tail and pointed ears, probably arboreal in its habits, and an inhabitant of the Old World." (vol. ii. p. 372) Mr. Darwin adds: "He who denounces these views (as irreligious) is bound to explain why it is more irreligious to explain the origin of man as a distinct species by descent from some lower form, through the laws of variation and natural selection, than to explain the birth of the individual through the laws of ordinary reproduction." (vol. ii. p. 378) FOOTNOTE: [7] _Descent of Man_, etc. By Charles Darwin, M. A., F. R. S., etc. New York, 1871, vol. i. p. 179. _The Sense in which Mr. Darwin uses the Word "Natural."_ We have not yet reached the heart of Mr. Darwin's theory. The main idea of his system lies in the word "natural." He uses that word in two senses: first, as antithetical to the word artificial. Men can produce very marked varieties as to structure and habits of animals. This is exemplified in the production of the different breeds of horses, cattle, sheep, and dogs; and specially, as Mr. Darwin seems to think, in the case of pigeons. Of these, he says, "The diversity of breeds is something astonishing." Some have long, and some very short bills; some have large feet, some small; some long necks, others long wings and tails, while others have singularly short tails; some have thirty, and even forty, tail-feathers, instead of the normal number of twelve or fourteen. They differ as much in instinct as they do in form. Some are carriers, some pouters, some tumblers, some trumpeters; and yet all are descendants of the Rock Pigeon which is still extant. If, then, he argues, man, in a comparatively short time, has by artificial selection produced all these varieties, what might be accomplished on the boundless scale of nature, during the measureless ages of the geologic periods. Secondly, he uses the word natural as antithetical to supernatural. Natural selection is a selection made by natural laws, working without intention and design. It is, therefore, opposed not only to artificial selection, which is made by the wisdom and skill of man to accomplish a given purpose, but also to supernatural selection, which means either a selection originally intended by a power higher than nature; or which is carried out by such power. In using the expression Natural Selection, Mr. Darwin intends to exclude design, or final causes. All the changes in structure, instinct, or intelligence, in the plants or animals, including man, descended from the primordial germ, or animalcule, have been brought about by unintelligent physical causes. On this point he leaves us in no doubt. He defines nature to be "the aggregate action and product of natural laws; and laws are the sequence of events as ascertained by us." It had been objected that he often uses teleological language, speaking of purpose, intention, contrivance, adaptation, etc. In answer to this objection, he says: "It has been said, that I speak of natural selection as a power or deity; but who objects to an author speaking of the attraction of gravity as ruling the movements of the planet?" He admits that in the literal sense of the words, natural selection is a false term; but "who ever objected to chemists, speaking of the elective affinities of various elements?--and yet an acid cannot strictly be said to elect the base with which it in preference combines." (p. 93) We have here an affirmation and a negation. It is affirmed that natural selection is the operation of natural laws, analogous to the action of gravitation and of chemical affinities. It is denied that it is a process originally designed, or guided by intelligence, such as the activity which foresees an end and consciously selects and controls the means of its accomplishment. Artificial selection, then, is an intelligent process; natural selection is not. There are in the animal and vegetable worlds innumerable instances of at least apparent contrivance, which have excited the admiration of men in all ages. There are three ways of accounting for them. The first is the Scriptural doctrine, namely, that God is a Spirit, a personal, self-conscious, intelligent agent; that He is infinite, eternal, and unchangeable in his being and perfections; that He is ever present; that this presence is a presence of knowledge and power. In the external world there is always and everywhere indisputable evidence of the activity of two kinds of force: the one physical, the other mental. The physical belongs to matter, and is due to the properties with which it has been endowed; the other is the everywhere present and ever acting mind of God. To the latter are to be referred all the manifestations of design in nature, and the ordering of events in Providence. This doctrine does not ignore the efficiency of second causes; it simply asserts that God over-rules and controls them. Thus the Psalmist says, "I am fearfully and wonderfully made.... My substance was not hid from thee, when I was made in secret, and curiously wrought (or embroidered) in the lower parts of the earth. Thine eyes did see my substance yet being imperfect; and in thy book all my members were written, which in continuance were fashioned, when as yet there were none of them." "He who fashioned the eye, shall not He see? He that formed the ear shall not He hear?" "God makes the grass to grow, and herbs for the children of men." He sends rain, frost, and snow. He controls the winds and the waves. He determines the casting of the lot, the flight of an arrow, and the falling of a sparrow. This universal and constant control of God is not only one of the most patent and pervading doctrines of the Bible, but it is one of the fundamental principles of even natural religion. The second method of accounting for contrivances in nature admits that they were foreseen and purposed by God, and that He endowed matter with forces which He foresaw and intended should produce such results. But here his agency stops. He never interferes to guide the operation of physical causes. He does nothing to control the course of nature, or the events of history. On this theory it may be said, (1.) That it is utterly inconsistent with the Scriptures. (2.) It does not meet the religious and moral necessities of our nature. It renders prayer irrational and inoperative. It makes it vain for a man in any emergency to look to God for help. (3.) It is inconsistent with obvious facts. We see around us innumerable evidences of the constant activity of mind. This evidence of mind and of its operations, according to Lord Brougham and Dr. Whewell, is far more clear than that of the existence of matter and of its forces. If one or the other is to be denied, it is the latter rather than the former. Paley indeed says, that if the construction of a watch be an undeniable evidence of design it would be a still more wonderful manifestation of skill, if a watch could be made to produce other watches; and, it may be added, not only other watches, but all kinds of time-pieces in endless variety. So it has been asked, if man can make a telescope, why cannot God make a telescope which produces others like itself? This is simply asking, whether matter can be made to do the work of mind? The idea involves a contradiction. For a telescope to make a telescope, supposes it to select copper and zinc in due proportions and fuse them into brass; to fashion that brass into inter-entering tubes; to collect and combine the requisite materials for the different kinds of glass needed; to melt them, grind, fashion, and polish them; adjust their densities and focal distances, etc., etc. A man who can believe that brass can do all this, might as well believe in God. The most credulous men in the world are unbelievers. The great Napoleon could not believe in Providence; but he believed in his star, and in lucky and unlucky days. This banishing God from the world is simply intolerable, and, blessed be his name, impossible. An absent God who does nothing is, to us, no God. Christ brings God constantly near to us. He said to his disciples, "Consider the ravens, for they neither sow nor reap; which have neither store-house nor barn; and God feedeth them; how much better are ye than the fowls. And which of you by taking thought can add to his stature one cubit? Consider the lilies how they grow; they toil not, neither do they spin; and yet I say unto you that Solomon in all his glory was not arrayed like one of these. If then God so clothe the grass, which is to-day in the field, and to-morrow is cast into the oven; how much more will He clothe you, O ye of little faith." "And seek ye not what ye shall eat, or what ye shall drink, neither be ye of doubtful mind. For all these things do the nations of the world seek after; and your Father knoweth that ye have need of these things." It may be said that Christ did not teach science. True, but He taught truth; and science, so called, when it comes in conflict with truth, is what man is when he comes in conflict with God. The advocates of these extreme opinions protest against being considered irreligious. Herbert Spencer says, that his doctrine of an inscrutable, unintelligent, unknown force, as the cause of all things, is a much more religious doctrine than that of a personal, intelligent, and voluntary Being of infinite power and goodness. Matthew Arnold holds that an unconscious "power which makes for right," is a higher idea of God than the Jehovah of the Bible. Christ says, God is a Spirit. Holbach thought that he made a great advance on that definition, when he said, God is motion. The third method of accounting for the contrivances manifested in the organs of plants and animals, is that which refers them to the blind operation of natural causes. They are not due to the continued coöperation and control of the divine mind, nor to the original purpose of God in the constitution of the universe. This is the doctrine of the Materialists, and to this doctrine, we are sorry to say, Mr. Darwin, although himself a theist, has given in his adhesion. It is on this account the Materialists almost deify him. From what has been said, it appears that Darwinism includes three distinct elements. First, evolution; or the assumption that all organic forms, vegetable and animal, have been evolved or developed from one, or a few, primordial living germs; second, that this evolution has been effected by natural selection, or the survival of the fittest; and third, and by far the most important and only distinctive element of his theory, that this natural selection is without design, being conducted by unintelligent physical causes. Neither the first nor the second of these elements constitute Darwinism; nor do the two combined. As to the first, namely, evolution, Mr. Darwin himself, in the historical sketch prefixed to the fifth edition of his "Origin of Species," says, that Lamarck, in 1811 and more fully in 1815, "taught that all species, including man, are descended from other species." He refers to some six or eight other scientists, as teaching the same doctrine. This idea of Evolution was prominently presented and elaborated in the "Vestiges of Creation," first published in 1844. Ulrici, Professor in the University of Halle, Germany, in his work "Gott und die Natur," says that the doctrine of evolution took no hold on the minds of scientific men, but was positively rejected by the most eminent physiologists, among whom he mentions J. Müller, K. Wagner, Bischoff, Hoffmann, and others.[8] The Rev. George Henslow, Lecturer on Botany at St. Bartholomew's Hospital, London, himself a pronounced evolutionist, says the theories of Lamarck and of the "Vestiges of Creation" have given place to that of Mr. Darwin; "and there are not wanting many symptoms of decay in the acceptance even of his. Not only has he considerably modified his views in later editions of the 'Origin of Species,' distinctly expressing the opinion that he attributed too great influence to natural selection, but even men of science, Owen, Huxley,--and at least in its application to man, Wallace himself,--are either opposed to it in great measure, or else give it but a qualified assent. Thus, it has been the fate of all theories of the development of living things to lapse into oblivion. _Evolution_ itself, however, will stand the same."[9] We find in the "Transactions of the Victoria Institute," a still more decided repudiation of Darwinism on the part of Mr. Henslow. He there says: "I do not believe in Darwin's theory; and have endeavored to refute it by showing its utter impossibility."[10] He defines Evolution by saying, "It supposes all animals and plants that exist now, or have ever existed, to have been produced through laws of generation from preëxisting animals and plants respectively; that affinity amongst organic beings implies, or is due to community of descent; and that the degree of affinity between organisms is in proportion to their nearness of generation, or, at least, to the persistence of common characters, they being the products of originally the same parentage."[11] A man, therefore, may be an evolutionist, without being a Darwinian. It should be mentioned that Mr. Henslow expressly excludes man, both as to body and soul, from the law of evolution. Nor is the theory of natural selection the vital principle of Mr. Darwin's theory, unless the word natural be taken in a sense antithetical to supernatural. In the historical sketch just referred to, Mr. Darwin not only says that he had been anticipated in teaching the doctrine of Evolution by Lamarck and the author of the "Vestiges of Creation;" but that the theory of natural selection, as the means of accounting for evolution, was not original with him. He tells us that as early as 1813, Dr. W. C. Wells "distinctly recognizes the principle of natural selection;" and that Mr. Patrick Matthew, in 1831, "gives precisely the same view of the origin of species as that propounded by Mr. Wallace and myself." Ideas are like seed: they are often cast forth, and not finding a congenial soil produce no fruit. To Mr. Darwin is undoubtedly due the elaboration and thoroughly scientific defence of the theory of natural selection, and to him is to be referred the deep and widespread interest which it has excited. FOOTNOTES: [8] _Gott und die Natur_. Von D. Hermann Ulrici. Zweite Auflage. Leipzig, 1866, p. 394. [9] _The Theory of Evolution of Living Things and the Application of the Principles of Evolution to Religion_. By Rev. George Henslow, M. A., F. L. S., F. G. S. London, 1873, pp. 27, 28. [10] _Journal of the Transactions of the Victoria Institute, or Philosophical Society of Great Britain_. Vol. iv. London, 1870, p. 278. [11] _Evolution and Religion_, p. 29. _Darwinism excludes Teleology._ It is however neither evolution nor natural selection, which give Darwinism its peculiar character and importance. It is that Darwin rejects all teleology, or the doctrine of final causes. He denies design in any of the organisms in the vegetable or animal world. He teaches that the eye was formed without any purpose of producing an organ of vision. Although evidence on this point has already been adduced, yet as it is often overlooked, at least in this country, so that many men speak favorably of Mr. Darwin's theory, who are no more Darwinians than they are Mussulmans; and as it is this feature of his system which brings it into conflict not only with Christianity, but with the fundamental principles of natural religion, it should be clearly established. The sources of proof on this point are,--1st. Mr. Darwin's own writings. 2d. The expositions of his theory given by its advocates. 3d. The character of the objections urged by its opponents. The point to be proved is that it is the distinctive doctrine of Mr. Darwin, that species owe their origin, not to the original intention of the divine mind; not to special acts of creation calling new forms into existence at certain epochs; not to the constant and everywhere operative efficiency of God, guiding physical causes in the production of intended effects; but to the gradual accumulation of unintended variations of structure and instinct, securing some advantage to their subjects. _Darwin's own Testimony._ That such is Mr. Darwin's doctrine we prove from his own writings. And the first proof from that source is found in express declarations. When an idea pervades a book and constitutes its character, detached passages constitute a very small part of the evidence of its being inculcated. In the present case, however, such passages are sufficient to satisfy even those who have not had occasion to read Mr. Darwin's books. In referring to the similarity of structure in animals of the same class, he says, "Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or the doctrine of final causes."[12] On the last page of his work, he says: "It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being growth with reproduction; variability from the indirect and direct action of the conditions of life, and from use and disuse; a ratio of increase so high as to lead to a struggle for life, and as a consequence to natural selection, entailing divergence of character and extinction of less improved forms. Thus from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, the production of the higher animals directly follows. There is a grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved." (p. 579) In another of his works, he asks, "Did He (God) ordain that crop and tail-feathers of the pigeon should vary, in order that the fancier might make his grotesque pouter and fan-tail breeds? Did He cause the frame and mental qualities of the dog to vary, in order that a breed might be formed of indomitable ferocity, with jaws fitted to pin down the bull, for man's brutal sport? But if we give up the principle in one case; if we do not admit that the variations of the primeval dog were intentionally guided in order, for instance, that the greyhound, that perfect image of symmetry and vigor, might be formed; no shadow of reason can be assigned for the belief that variations, alike in nature and the results of the same general laws, which have been the groundwork through natural selection of the most perfectly adapted animals in the world, man included, were intentionally and specially guided. However much we may wish it, we can hardly follow Professor Asa Gray, in his belief 'that variations have been led along certain beneficial lines, as a stream is led along useful lines of irrigation.'"[13] Variations, which by their gradual accumulation give rise to new species, genera, families, and orders, are themselves, step by step, accidental. Mr. Darwin sometimes says they happen by chance; sometimes he says they happen of necessity; at others he says, "We are profoundly ignorant of their causes." These are only different ways of saying that they are not intentional. When a man lets anything fall from his hands, and says it was accidental, he does not mean that it was causeless, he only means that it was not intentional. And that is precisely what Darwin means when he says that species arise out of accidental variations. His whole book is an argument against teleology. The whole question is, How are we to account for the innumerable varieties, kinds, and genera of plants and animals, including man? Were they intended? or, Did they arise from the gradual accumulations of unintentional variations? His answer to these questions is plain. On page 245, he says: "Nothing at first can appear more difficult to believe than that the more complex organs and instincts have been perfected not by means superior to, though analogous with, human reason, but by innumerable slight variations, each good for the individual possessor. Nevertheless, this difficulty, though appearing to our imagination[14] insuperably great, cannot be considered real, if we admit the following propositions, namely, that all parts of the organizations and instincts offer, at least, individual differences; that there is a struggle for existence, which leads to the preservation of profitable deviations of structure or instinct; and, lastly, that gradations in the state of perfection of each organ may have existed, each good of its kind." He says, over and over, that if beauty or any variation of structure can be shown to be intended, it would "annihilate his theory." His doctrine is that such unintended variations, which happen to be useful in the struggle for life, are preserved, on the principle of the survival of the fittest. He urges the usual objections to teleology derived from undeveloped or useless organs, as web-feet in the upland goose and frigate-bird, which never swim. What, however, perhaps more than anything, makes clear his rejection of design is the manner in which he deals with the complicated organs of plants and animals. Why don't he say, they are the product of the divine intelligence? If God made them, it makes no difference, so far as the question of design is concerned, how He made them: whether at once or by a process of evolution. But instead of referring them to the purpose of God, he laboriously endeavors to prove that they may be accounted for without any design or purpose whatever. "To suppose," he says, "that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different degrees of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree." (p. 222) Nevertheless he attempts to explain the process. "It is scarcely possible," he says, "to avoid comparing the eye with the telescope. We know that this instrument has been perfected by the long continued efforts of the highest of human intellects; and we naturally infer that the eye has been formed by a somewhat analogous process. But may not this inference be presumptuous? Have we any right to assume that the Creator works by intellectual powers like those of man? If we must compare the eye to an optical instrument, we ought in imagination to take a thick layer of transparent tissue, with spaces filled with fluid, and with a nerve sensitive to light beneath, and then suppose every part of this layer to be continually changing slowly in density, so as to separate into layers of different densities and thicknesses, placed at different distances from each other, and with the surfaces of each layer slowly changing in form. Further, we must suppose that there is a power represented by natural selection, or the survival of the fittest, always intently watching each slight alteration in the transparent layers, and carefully preserving each, which, under varied circumstances, tends to produce a distinct image. We must suppose each new state of the instrument to be multiplied by the million; each to be preserved until a better is produced, and the old ones to be all destroyed. In living bodies, variations will cause the slight alterations, generation will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement."[15] (p. 226) "Let this process," he says, "go on for millions of years," and we shall at last have a perfect eye. It would be absurd to say anything disrespectful of such a man as Mr. Darwin, and scarcely less absurd to indulge in any mere extravagance of language; yet we are expressing our own experience, when we say that we regard Mr. Darwin's books the best refutation of Mr. Darwin's theory. He constantly shuts us up to the alternative of believing that the eye is a work of design or the product of the unintended action of blind physical causes. To any ordinarily constituted mind, it is absolutely impossible to believe that it is not a work of design. Darwin himself, it is evident, dear as his theory is, can hardly believe it. "It is indispensable," he says, "to arrive at a just conclusion as to the formation of the eye, that the reason should conquer the imagination; but I have felt the difficulty far too keenly to be surprised at any degree of hesitation in extending the principle of natural selection to so startling an extent." (p. 225) It will be observed that every step in his account of the formation of the eye is an arbitrary assumption. We must first assume a thick layer of tissue; then that the tissue is transparent; then that it has cavities filled with fluid; that beneath the tissue is a nerve sensitive to light; then that the fluid is constantly varying in density and thickness; that its surfaces are constantly changing their contour; that its different portions are ever shifting their relative distances; that every favorable change is seized upon and rendered permanent,--thus after millions of years we may get an eye as perfect as that of an eagle. In like manner we may suppose a man to sit down to account for the origin and contents of the Bible, assuming as his "working hypothesis," that it is not the product of mind either human or divine, but that it was made by a type-setting machine worked by steam, and picking out type hap-hazard. In this way in a thousand years one sentence might be produced, in another thousand a second, and in ten thousand more, the two might get together in the right position. Thus in the course of "millions of years" the Bible might have been produced, with all its historical details, all its elevated truths, all its devout and sublime poetry, and above all with the delineation of the character of Christ, the [Greek: idea tôn ideôn], the ideal of majesty and loveliness, before which the whole world, believing and unbelieving, perforce bows down in reverence. And when reason has sufficiently subdued the imagination to admit all this, then by the same theory we may account for all the books in all languages in all the libraries in the world. Thus we should have Darwinism applied in the sphere of literature. This is the theory which we are told is to sweep away Christianity and the Church! Mr. Darwin gives the same unsatisfactory account of the marvellous "contrivances" in the vegetable world. In one species of Orchids, the labellum or lower lip is hollowed into a great bucket continually filled with water, secreted from two horns which stand above it; when the bucket is sufficiently filled, the water flows out through a pipe or spout on one side. The bees, which crowd into the flower for sake of the nectar, jostle each other, so that some fall into the water; and their wings becoming wet they are unable to fly, and are obliged to crawl through the spout. In doing this they come in contact with the pollen, which, adhering to their backs, is carried off to other flowers. This complicated contrivance by which the female plants are fertilized has, according to the theory, been brought about by the slow process of natural selection or survival of the fittest. Still more wonderful is the arrangement in another species of Orchids. When the bee begins to gnaw the labellum, he unavoidably touches a tapering projection, which, when touched, transmits a vibration which ruptures a membrane, which sets free a spring by which a mass of pollen is shot, with unerring aim, over the back of the bee, who then departs on his errand of fertilization. A very large class of plants are fertilized by means of insects. These flowers are beautiful, not for the sake of beauty,--for that Mr. Darwin says would annihilate his theory,--but those which happen to be beautiful attract insects, and thus become fertilized and perpetuated, while the plainer ones are neglected and perish. So with regard to birds. The females are generally plain, because those of bright colors are so exposed during the period of incubation that they are destroyed by their enemies. In like manner male birds are usually adorned with brilliant plumage. This is accounted for on the ground that they are more attractive, and thus they propagate their race, while the plainer ones have few or no descendants. Thus all design is studiously and laboriously excluded from every department of nature. The preceding pages contain only a small part of the evidence furnished by Mr. Darwin's own writings, that his doctrine involves the denial of all final causes. The whole drift of his books is to prove that all the organs of plants and animals, all their instincts and mental endowments, may be accounted for by the blind operation of natural causes, without any intention, purpose, or coöperation of God. This is what Professor Huxley and others call "the creative idea," to which the widespread influence of his writings is to be referred. FOOTNOTES: [12] _Origin of Species_, p. 517. [13] _The Variations of Animals and Plants under Domestication._ By Charles Darwin, F. R. S., etc. New York, 1868, vol. ii. pp. 515, 516. [14] What can the word "imagination" mean in this sentence, if it does not mean "Common Sense?" [15] Mr. Darwin's habit of personifying nature has given, as his friend Mr. Wallace says, his readers a good deal of trouble. He defines nature to be the aggregate of physical forces; and in the single passage quoted, he speaks of Natural Selection "as intently watching" "picking out with unerring skill," and "carefully preserving." It is true, he tells us this is all to be understood metaphorically. _Testimony of the Advocates of the Theory._ It is time to turn to the exposition of Darwinism by its avowed advocates, in proof of the assertion that it excludes all teleology. The first of these witnesses is Mr. Alfred Russel Wallace, himself a distinguished naturalist. Mr. Darwin informs his readers that as early as 1844, he had collected his material and worked out his theory, but had not published it to the world, although it had been communicated to some of his friends. In 1858 he received a memoir from Mr. Wallace, who was then studying the natural history of the Malay Archipelago. From that memoir he learnt that Mr. Wallace had "arrived at almost exactly the same conclusions as I (he himself) have on the origin of species." This led to the publishing his book on that subject contemporaneously with Mr. Wallace's memoir. There has been no jealousy or rivalry between these gentlemen. Mr. Wallace gracefully acknowledges the priority of Mr. Darwin's claim, and attributes to him the credit of having elaborated and sustained it in a way to secure for it universal attention. These facts are mentioned in order to show the competency of Mr. Wallace as a witness as to the true character of Darwinism. Mr. Wallace, in "The Theory of Natural Selection," devotes a chapter to the consideration of the objections urged by the Duke of Argyll, in his work on the "Reign of Law," against that theory. Those objections are principally two: first, that design necessarily implies an intelligent designer; and second, that beauty not being an advantage to its possessor in the struggle for life, cannot be accounted for on the principle of the survival of the fittest. The Duke, he says, maintains that contrivance and beauty indicate "the constant supervision and interference of the Creator, and cannot possibly be explained by the unassisted action of any combination of laws. Now, Mr. Darwin's work," he adds, "has for its main object to show that all the phenomena of living things--all their wonderful organs and complicated structures, their infinite variety of form, size, and color, their intricate and involved relations to each other--may have been produced by the action of a few general laws of the simplest kind, laws which are in most cases mere statements of admitted facts." (p. 265) Those laws are those with which we are familiar: Heredity, Variations, Over Production, Struggle for Life, Survival of the Fittest. "It is probable," he says, "that these primary facts or laws are but results of the very nature of life, and of the essential properties of organized and unorganized matter. Mr. Herbert Spencer, in his 'First Principles' and in his 'Biology,' has, I think, made us able to understand how this may be; but at present we may accept these simple laws, without going further back, and the question then is, Whether the variety, the harmony, the contrivance, and the beauty we perceive, can have been produced by the action of these laws alone, or whether we are required to believe in the incessant interference and direct action of the mind and will of the Creator." (p. 267)[16] Mr. Wallace says, that the Duke of Argyll maintains that God "has personally applied general laws to produce effects which those laws are not in themselves capable of producing; that the universe alone with all its laws intact, would be a sort of chaos, without variety, without harmony, without design, without beauty; that there is not (and therefore we may presume that there could not be) any self-developing power in the universe. I believe, on the contrary, that the universe is so constituted as to be self-regulating; that as long it contains life, the forms under which that life is manifested have an inherent power of adjustment to each other and to their surroundings; and that this adjustment necessarily leads to the greatest amount of variety and beauty and enjoyment, because it does depend on general laws, and not on a continual supervision and rearrangement of details." (p. 268) "The strange springs and traps and pitfalls found in the flowers of Orchids, cannot," he says, "be necessary _per se_, since exactly the same end is gained in ten thousand other flowers which do not possess them. Is it not then an extraordinary idea, to imagine the Creator of the universe contriving the various complicated parts of these flowers, as a mechanic might contrive an ingenious toy or a difficult puzzle? Is it not a more worthy conception, that they are the results of those general laws which were so coördinated at the first introduction of life upon the earth as to result necessarily in the utmost possible development of varied forms." (p. 270) "I for one," he says, "cannot believe that the world would come to chaos if left to law alone.... If any modification of structure could be the result of law, why not all? If some self-adaptations should arise, why not others? If any varieties of color, why not all the varieties we see? No attempt is made to explain this except by reference to the fact that 'purpose' and 'contrivance' are everywhere visible, and by an illogical deduction they could only have arisen by the direct action of some mind, because the direct action of our minds produce similar 'contrivances;' but it is forgotten that adaptation, however produced, must have the appearance of design." (p. 280)[17] After referring to the fact that florists and breeders can produce varieties in plants and animals, so that, "whether they wanted a bull-dog to torture another animal, a greyhound to catch a hare, or a bloodhound to hunt down their oppressed fellow-creatures, the required variations have always appeared," he adds: "To be consistent, our opponents must maintain that every one of the variations that have rendered possible the changes produced by man, have been determined at the right time and place by the Creator. Every race produced by the florist or breeder, the dog or the pigeon fancier, the rat-catcher, the sporting man, or the slave-hunter, must have been provided for by varieties occurring when wanted; and as these variations were never withheld, it would prove that the sanction of an all-wise and all powerful Being has been given to that which the highest human minds consider to be trivial, mean, or debasing." (p. 290)[18] The Nebular Hypothesis, as propounded by La Place, proposed to account for the origin of the universe, by a process of evolution under the control of mere physical forces. That hypothesis has, so far as evolution is concerned, been adopted by men who sincerely believe in God and in the Bible. But they hold not only that God created matter and endowed it with its properties, but that He designed the universe, and so controlled the operation of physical laws that they accomplished his purpose. So there are Christian men who believe in the evolution of one kind of plants and animals out of earlier and simpler forms; but they believe that everything was designed by God, and that it is due to his purpose and power that all the forms of vegetable and animal life are what they are. But this is not the question. What Darwin and the advocates of his theory deny, is all design. The organs, even the most complicated and wonderful, were not intended. They are said to be due to the undirected and unintended operation of physical laws. This is Mr. Wallace's argument. He endeavors to show that it is unworthy of God that He should be supposed to have contrived the mechanism of the orchids, as a mechanist contrives a curious puzzle. We recently heard Prof. Joseph Henry, in a brief address, say substantially: "If I take brass, glass, and other materials, and fuse them, the product is a slag. This is what physical laws do. If I take those same materials, and form them into a telescope, that is what mind does." This is the whole question in a nutshell. That design implies an intelligent designer, is a self evident truth. Every man believes it; and no man can practically disbelieve it. Even those naturalists who theoretically deny it, if they find in a cave so simple a thing as a flint arrow-head, are as sure that it was made by a man as they are of their own existence. And yet they want us to believe that an eagle's eye is the product of blind natural causes. No combination of physical forces ever made a ship or a locomotive. It may, indeed, be said that they are dead matter, whereas plants and animals live. But what is life but one form of the organizing efficiency of God? Mr. Wallace does not go as far as Mr. Darwin. He recoils from regarding man either as to body or soul as the product of mere natural causes. He insists that "a superior intelligence is necessary to account for man." (p. 359) This of course implies that the agency of no such higher intelligence is admitted in the production of plants or of animals lower than man. FOOTNOTES: [16] The question is not, as Mr. Wallace says, "How has the Creator worked?" but it is, as he himself states, whether the essential properties of matter have alone worked out all the wonders of creation; or, whether they are to be referred to the mind and will of God. It is worthy of remark how Messrs. Darwin and Wallace refer to Mr. Spencer as their philosopher. We have seen what Spencer's philosophy is. [17] It is, therefore, clear that design is what Mr. Darwin and Mr. Wallace repudiate. [18] That God permits men in the use of the laws of nature to distil alcohol and brew poisons, does not prove that He approves of drunkenness or murder. _Professor Huxley._ The second witness as to the character of Mr. Darwin's theory is Professor Huxley. We have some hesitation in including the name of this distinguished naturalist among the advocates of Darwinism.[19] On the one hand, in his Essay on the Origin of Species, printed in the "Westminster Review," in 1860, and reprinted in his "Lay Sermons," etc., in 1870, he says: "There is no fault to be found with Mr. Darwin's method, but it is another thing whether he has fulfilled all the conditions imposed by that method. Is it satisfactorily proved that species may[20] be originated by selection? that none of the phenomena exhibited by species are inconsistent with the origin of species in this way? If these questions can be answered in the affirmative, Mr. Darwin's view steps out of the rank of hypotheses into that of theories; but so long as the evidence at present adduced falls short of enforcing that affirmative, so long, to our minds, the new doctrine must be content to remain among the former,--an extremely valuable, and in the highest degree probable, doctrine; indeed, the only extant hypothesis which is worth anything in a scientific point of view; but still a hypothesis, and not yet a theory of species. After much consideration," he adds, "and assuredly with no bias against Mr. Darwin's views, it is our clear conviction that, as the evidence now stands, it is not absolutely proven that a group of animals, having all the characters exhibited by species in Nature, has ever been originated by selection, whether artificial or natural."[21] Again, in his work on "Man's Place in Nature," he expresses himself much to the same effect: "A true physical cause is admitted to be such only on one condition, that it shall account for all the phenomena which come within the range of its operation. If it is inconsistent with any one phenomenon it must be rejected; if it fails to explain any one phenomenon it is so far to be suspected, though it may have a perfect right to provisional acceptance.... Our acceptance, therefore, of the Darwinian hypothesis must be provisional so long as one link in the chain of evidence is wanting; and so long as all the animals and plants certainly produced by selective breeding from a common stock are fertile, and their progeny are fertile one with another, that link will be wanting. For so long selective breeding will not be proved to be competent to all that is required if it produce natural species."[22] In immediate connection with the above passage, there is another which throws a clear light on Professor Huxley's cosmical views. "The whole analogy of natural operations furnish so complete and crushing an argument against the intervention of any but what are called secondary causes, in the production of all the phenomena of the universe; that, in view of the intimate relations of man and the rest of the living world, and between the forces exerted by the latter and all other forces, I can see no reason for doubting that all are coördinate terms of nature's great progression, from formless to formed, from the inorganic to the organic, from blind force to conscious intellect and will."[23] Ought not this to settle the matter? Are we to give up the Bible and all our hopes for the sake of an hypothesis that all living things, including man, on the face of the earth, are descended from a primordial animalcule, by natural selection, when such a man as Huxley, who (as Voltaire said of the prophet Habbakuk) is _capable de tout_, says that it has not been proved that any one species has thus originated? But on the other hand, while he honestly admits that Darwin's doctrine is a mere hypothesis and not a theory, he has nevertheless written at least three essays or reviews in its exposition and vindication. He is freely referred to on the continent of Europe, at least, as an ardent advocate of the doctrine; and he quotes without protest such designations of himself. At any rate, as he assures his readers that he has no bias against Mr. Darwin's views, as he has devoted much time and attention to the subject, and as he is one of the most prominent naturalists of the age, there can be no question as to his competency as a witness as to what Darwinism is. His testimony that Mr. Darwin's doctrine excludes all teleology, or final causes, is explicit. In his review of the "Criticisms on the Origin of Species," he says, "that when he first read Mr. Darwin's book, that which struck him most forcibly was the conviction that teleology, as commonly understood, had received its death-blow at Mr. Darwin's hands. For the teleological argument runs thus: An organ is precisely fitted to perform a function or purpose; therefore, it was specially constructed to perform that function. In Paley's famous illustration, the adaptation of all the parts of a watch to the function or purpose of showing the time, is held to be evidence that the watch was specially contrived to that end; on the ground that the only cause we know of competent to produce such an effect as a watch which shall keep time, is a contriving intelligence adapting the means directly to that end."[24] This, Mr. Huxley tells us, is precisely what Darwin denies with reference to the organs of plants and animals. The eye was not formed for the purpose of seeing, or the ear for hearing. It so happened that a nerve became sensitive to light; then in course of time, it happened that a transparent tissue came over it; and thus in "millions of years" an eye, as we have seen above, happened to be formed. No such organ was ever intended or designed by God or man. "An apparatus," says Professor Huxley, "thoroughly adapted to a particular purpose, might be the result of a method of trial and error worked by unintelligent agents, as well as by the application of means appropriate to the end by an intelligent agent." "For the notion that every organism has been created as it is and launched straight at a purpose, Mr. Darwin substitutes the conception of something, which may fairly be termed a method of trial and error. Organisms vary incessantly; of these variations the few meet with surrounding conditions which suit them, and thrive; the many are unsuited, and become extinguished." "For the teleologist an organism exists, because it was made for the conditions in which it is found; for the Darwinian an organism exists, because, out of many of its kind, it is the only one which has been able to persist in the conditions in which it is found." "If we apprehend," Huxley further says, "the spirit of the 'Origin of Species' rightly, then, nothing can be more entirely and absolutely opposed to teleology, as it is commonly understood, than the Darwinian theory." (p. 303) It has already been stated that Mr. Wallace does not apply the doctrine of evolution to man; neither does Mr. Mivart, a distinguished naturalist, who is a member of the Latin Church. The manner in which Professor Huxley speaks of these gentlemen shows how thoroughly, in his judgment, Mr. Darwin banishes God from his works: "Mr. Wallace and Mr. Mivart are as stout evolutionists as Mr. Darwin himself; but Mr. Wallace denies that man can have been evolved from a lower animal by that process of natural selection, which he, with Mr. Darwin, holds to be sufficient for the evolution of all animals below man; while Mr. Mivart, admitting that natural selection has been one of the conditions of the animals below man, maintains that natural selection must, even in their case, have been supplemented by some other cause,--of the nature of which, unfortunately, he does not give us any idea. Thus Mr. Mivart is less of a Darwinian than Mr. Wallace, for he has faith in the power of natural selection. But he is more of an evolutionist than Mr. Wallace, because Mr. Wallace thinks it necessary to call in an intelligent agent, a sort of supernatural Sir John Sebright, to produce even the animal frame of man; while Mr. Mivart requires no Divine assistance till he comes to man's soul."[25] In the "Academy" for October, 1869, there is a review by Professor Huxley of Dr. Haeckel's "Natürlische Schöpfungsgeschichte," in which he says: "Professor Haeckel enlarges on the service which the 'Origin of Species' has done in favoring what he terms 'the causal or mechanical' view of living nature as opposed to the 'teleological or vitalistic' view. And no doubt it is quite true the doctrine of evolution is the most formidable of all the commoner and coarser forms of teleology. Perhaps the most remarkable service to the philosophy of Biology rendered by Mr. Darwin is the reconciliation of Teleology and Morphology, and the explanation of the facts of both which his view offers. "The teleology which supposes that the eye, such as we see it in man or in the higher vertebrata, was made with the precise structure which it exhibits, to make the animal which possesses it to see, has undoubtedly received its death-blow. But it is necessary to remember that there is a higher teleology, which is not touched by the doctrine of evolution, but is actually based on the fundamental proposition of evolution. That proposition is, that the whole world, living and not living, is the result of the mutual interaction, according to definite laws, of forces possessed by the molecules of which the primitive nebulosity of the universe was composed. If this be true, it is no less certain that the existing world lay potentially in the cosmic vapor; and that a sufficient intelligence could, from a knowledge of the properties of that vapor, have predicted, say, the state of fauna of Great Britain in 1869, with as much certainty as one can say what will happen to the vapor of the breath on a cold winter's day." This is the doctrine of the self-evolution of the universe. We know not what may lie behind this in Mr. Huxley's mind; but we are very sure that there is not an idea in the above paragraph which Epicurus of old, and Büchner, Vogt, Haeckel, and other "Materialisten von Profession," would not cheerfully adopt. His distinction between a higher and lower teleology is of no account in this discussion. What is the teleology to which, he says, Mr. Darwin has given the death-blow, the extracts given above clearly show. The eye, Huxley says, was not made for the purpose of seeing, or the ear for the purpose of hearing. "According to teleology," he says, "each organism is like a rifle bullet fired straight at a mark; according to Darwin, organisms are like grapeshot, of which one hits something and the rest fall wide."[26] FOOTNOTES: [19] Mr. Huxley, if we may judge from what he says of himself, is somewhat liable to be misunderstood. He says he was fourteen years laboring to resist the charge of Positivism made against the class of scientific men to which he belongs. He also tells us in his letter to Professor Tyndall, prefixed to his volume of _Lay Sermons and Addresses_, that the "Essay on the Physical Basis of Life," included in that volume, was intended as a protest, from the philosophical side, against what is commonly called Materialism. It turned out, however, that the public regarded it as an argument in favor of Materialism. This we think was a very natural, if not an unavoidable mistake, on the part of the public. For in that Essay, he says that Protoplasm, or the physical basis of life, "is a kind of matter common to all living beings, that the powers or faculties of all kinds of living matter, diverse as they may be in degree, are substantially of the same kind." Protoplasm as far as examined contains the four elements,--carbon, hydrogen, oxygen, and nitrogen. These are lifeless bodies, "but when brought together under certain conditions, they give rise to the still more complex body Protoplasm; and this protoplasm exhibits the phenomena of life." There is no more reason, he teaches, for assuming the existence of a mysterious something called vitality to account for vital phenomena, than there is for the assumption of something called Aquasity to account for the phenomena of water. Life is said to be "the product of a certain disposition of material molecules." The matter of life is "composed of ordinary matter, differing from it only in the manner in which its atoms are aggregated. I take it," he says, "to be demonstrable that it is utterly impossible to prove that anything whatever may not be the effect of a material and necessary cause, and that human logic is equally incompetent to prove that any act is really spontaneous. A really spontaneous act is one, which, by the assumption, has no cause; and the attempt to prove such a negative as this, is on the face of the matter absurd. And while it is thus a philosophical impossibility to demonstrate that any given phenomenon is not the effect of a material cause, any one who is acquainted with the history of science will admit that its progress has, in all ages, meant, and now more than ever means, the extension of what we call matter and causation, and the concomitant gradual banishment from all regions of human thought of what we call spirit and spontaneity." [20] It cannot escape the attention of any one that Mr. Darwin, Mr. Wallace, Professor Huxley, and all the other advocates or defenders of Darwinism, do not pretend to prove anything more than that species _may_ be originated by selection, not that there is no other satisfactory account of their origin. Mr. Darwin admits that referring them to the intention and efficiency of God, accounts for everything, but, he says, that is not science. [21] _Lay Sermons, Addresses, and Reviews_. By Thomas Henry Huxley, LL. D., F. R. S. London, 1870, p. 323. [22] _Evidence of Man's Place in Nature_. London, 1864, p. 107. [23] Since writing the above paragraph our eye fell on the following note on the 89th page of the Duke of Argyle's _Reign of Law_, which it gives us pleasure to quote. It seems that a writer in the _Spectator_ had charged Professor Huxley with Atheism. In the number of that paper for February 10, 1866, the Professor replies: "I do not know that I care very much about popular odium, so there is no great merit in saying that if I really saw fit to deny the existence of a God I should certainly do so, for the sake of my own intellectual freedom, and be the honest atheist you are pleased to say I am. As it happens, however, I cannot take this position with honesty, inasmuch as it is, and always has been, a favorite tenet, that Atheism is as absurd, logically speaking, as Polytheism." In the same paper he says, "The denying the possibility of miracles seems to me quite as unjustifiable as speculative Atheism." How this can be reconciled with the passages quoted above, we are unable to see. [24] _Lay Sermons_, etc., p. 330. [25] _Contemporary Review_, vol. xviii. 1871, p. 444. In this same article Mr. Huxley says: "Elijah's great question, Will ye serve God or Baal? Choose ye, is uttered audibly enough in the ears of every one of us as we come to manhood. Let every man who tries to answer it seriously ask himself whether he can be satisfied with the Baal of authority, and with all the good things his worshippers are promised in this world and the next. If he can, let him, if he be so inclined, amuse himself with such scientific implements as authority tells him are safe and will not cut his fingers; but let him not imagine that he is, or can be, both a true son of the Church and a loyal soldier of science." "And, on the other hand, if the blind acceptance of authority appear to him in its true colors, as mere private judgment _in excelsis_, and if he have courage to stand alone face to face with the abyss of the Eternal and Unknowable, let him be content, once for all, not only to renounce the good things promised by 'Infallibility,' but even to bear the bad things which it prophesies; content to follow reason and fact in singleness and honesty of purpose, wherever they may lead, in the sure faith that a hell of honest men will to him be more endurable than a paradise full of angelic shams." There can be no doubt that the Apostle Paul believed in the infallibility of the Scriptures. Imagine Professor Huxley calling St. Paul to his face, a sham! What are all the Huxleys who have ever lived or ever can live, to that one Paul in power for good over human thought, character, and destiny! Professor Huxley goes on in the next paragraph to say: "Mr. Mivart asserts that 'without belief in a personal God there is no religion worthy of the name.' This is a matter of opinion. But it may be asserted, with less reason to fear contradiction, that the worship of a personal God, who, on Mr. Mivart's hypothesis, must have used words studiously calculated to deceive his creatures and worshippers, is 'no religion worthy of the name.' 'Incredibile est, Deum illis verbis ad populum fuisse locutum quibis deciperetur,' is a verdict in which for once Jesuit casuistry concurs with the healthy moral sense of all mankind." (p. 458). Mr. Huxley calls believers in the Scriptures, and (apparently) believers in a personal God, bigots, old ladies of both sexes, bibliolators, fools, etc., etc. [26] _Lay Sermons_, etc. p. 331. _Büchner._ Dr. Louis Büchner, president of the medical association of Hessen-Darmstadt, etc., etc., is not only a man of science but a popular writer. Perhaps no book of its class, in our day, has been so widely circulated as his volume on "Kraft und Stoff," Matter and Force. It has been translated into all the languages of Europe. He holds that matter and force are inseparable; there cannot be the one without the other; both are eternal and imperishable; neither can be either increased or diminished; life originated spontaneously by the combination of molecules of matter under favorable conditions; all the phenomena of the universe, inorganic and organic, whether physical, vital, or mental, are due to matter and its forces. Consequently there is no God, no creation, no mind distinct from matter, no conscious existence of man after death. All this is asserted in the most explicit terms. Dr. Büchner has published a work on Darwinism in two volumes. Darwin's theory, he says, "is the most thoroughly naturalistic that can be imagined, and far more atheistic than that of his decried predecessor Lamarck, who admitted at least a general law of progress and development; whereas, according to Darwin, the whole development is due to the gradual summation of innumerable minute and accidental operations."[27] FOOTNOTE: [27] _Sechs Vorlesungen über die Darwinische Theorie_. Von Ludwig Büchner. Zweite Auflage, Leipzig, 1848, vol. i. p. 125. _Carl Vogt._ In his preface to his work on the "Descent of Man," Mr. Darwin quotes this author as a high authority. We see him elsewhere referred to as one of the first physiologists of Germany. Vogt devotes the concluding lecture of the second volume of his work on Man, to the consideration of Darwinism. He expresses his opinion of it, after high commendation, in the following terms. He says that it cannot be doubted that Darwin's "theory turns the Creator--and his occasional intervention in the revolutions of the earth and in the production of species--without any hesitation out of doors, inasmuch as it does not leave the smallest room for the agency of such a Being. The first living germ being granted, out of it the creation develops itself progressively by natural selection, through all the geological periods of our planets, by the simple law of descent--no new species arises by creation and none perishes by divine annihilation--the natural course of things, the process of evolution of all organisms and of the earth itself, is of itself sufficient for the production of all we see. Thus Man is not a special creation, produced in a different way, and distinct from other animals, endowed with an individual soul and animated by the breath of God; on the contrary, Man is only the highest product of the progressive evolution of animal life springing from the group of apes next below him."[28] After this no one can be surprised to hear him say, that "the pulpits of the orthodox, the confessionals of the priests, the platforms of the interior missions, the presidential chairs of the consistories, resound with protestations against the assaults made by Materialism and Darwinism against the very foundations of society." (p. 286) This he calls "Das Wehgeschrei der Moralisten" (the Wail of the Moralists). The designation Moralists is a felicitous one, as applied to the opponents of Vogt and his associates. It distinguishes them as men who have not lost their moral sense; who refuse to limit their faith to what can be proved by the five senses; who bow to the authority of the law written by the finger of God, on the hearts of men, which neither sophistry nor wickedness can effectually erase. All Vogt thinks it necessary to reply to these Moralists is, "Lasst sie bellen, bis sie ausgebellt haben" (Let them bark till they are tired). "Ende." FOOTNOTE: [28] _Vorlesungen über den Menschen, seine Stellung in der Schoepfung und in der Geschichte der Erde_. Von Carl Vogt. Giessen, 1863, vol. ii. p. 260. _Haeckel._ Dr. Ernst Haeckel, Professor in the University of Jena, is said to stand at the head of the living naturalists of Germany. His work on "Natural History of Creation" contains a course of lectures delivered to the professors, students, and citizens of Jena. It is, therefore, somewhat popular in its character. The ability of the writer is manifest on every page. The distinctness of his perceptions, precision of language, perspicuity of style, and the strength of his convictions, give the impression of a man fully master of his subject, who has thought himself through, and is perfectly satisfied with the conclusions at which he has arrived. At the same time it is the impression of a man who is developed only on one side; who never looks within; who takes no cognizance of the wonders revealed in consciousness; to whom the intuitions of reason and of the conscience, the sense of dependence on a will higher than our own--the sense of obligation and responsibility are of no account,--in short a man to whom the image of God enstamped on the soul of man is invisible. This being the case, he that is least in the kingdom of heaven is greater than he. Haeckel admits that the title of his book, "Natural Creation," _i. e._ creation by natural laws, is a contradiction. He distinguishes, however, between the creation of substance and the creation of form. Of the former he says science knows nothing. To the scientist matter is eternal. If any one chooses to assume that it was created by an extramundane power, Haeckel says he will not object. But that is a matter of faith; and "where faith begins, science ends." The very reverse of this is true. Science must begin with faith. It cannot take a single step without it. How does Haeckel know that his senses do not deceive him? How does he know that he can trust to the operations of his intellect? How does he know that things are as they appear? How does he know that the universe is not a great phantasmagoria, as so many men have regarded it, and man the mere sport of chimeras? He must believe in the laws of belief impressed on his nature. Knowledge implies a mind that knows, and confidence in the act of knowing implies belief in the laws of mind. "An inductive science of nature," says President Porter, "presupposes a science of induction, and a science of induction presupposes a science of man."[29] Haeckel, however, says faith is the mere product of the poetic imagination; science, of the understanding; if its conclusions come into conflict with the creations of the imagination, the latter, of course, must give way.[30] He says, there have ever been two conflicting theories of the universe: the one, monistic; the other, dualistic. The one admits of only one substance, matter; the other of two, matter and mind. He prefers to call the former monism rather than materialism, because the latter term often includes the idea of moral materialism, _i. e._ the doctrine that sensual pleasure is the end of life; a doctrine, he says, much more frequently held by princely church-men than by men of science. He maintains, however, that "all knowable nature is one; that the same eternal, immutable (ehernen, brazen) laws are active in the life of animals and plants, in the formation of crystals, and the power of steam; in the whole sphere of biology, zoölogy, and botany. We have, therefore, the right to hold fast the monistic and mechanical view, whether men choose to brand the system as Materialism or not. In this sense, all natural science, with the law of causation at its head, is thoroughly materialistic." (p. 32) The monistic theory he calls "mechanical or causal," as distinguished from the dualistic theory, which he calls "teleological or vitalistic." According to the latter, "the vegetable and animal kingdoms are considered as the products of a creative agency, working with a definite design. In looking on an organism, the conviction seems unavoidable that so skilfully constructed a machine, such a complicated working apparatus, as an organism is, could be produced only by an agency analogous to, although far more perfect than the agency of man." "This," he says, "supposes the Creator to be an organism analogous to man, although infinitely more perfect; who contemplates his formative powers, lays the plan of the machine, and then, by the use of appropriate means, produces an effect answering to the preconceived plan.... However highly the Creator may be exalted, this view involves the ascription to Him of human attributes, in virtue of which he can form a plan, and construct organisms to correspond with it. That is the view to which Darwin's doctrine is directly opposed, and of which Agassiz is, among naturalists, the most important advocate. The famous work of Agassiz, 'Essay on Classification,' which is in direct opposition to Darwin's, and appeared about the same time, has carried out logically to the utmost the absurd anthropomorphic doctrine of a Creator." (p. 17) The monistic theory is called "mechanical and causal," because it supposes that all the phenomena of the universe, organic and inorganic, vegetable and animal, vital and mental, are due to mechanical or necessarily operating causes (causæ efficientes); just as the dualistic theory is called "teleological or vitalistic," because it refers natural organisms to causes working for the accomplishment of a given end (causæ finales). (p. 67) The grand difficulty in the way of the mechanical or monistic theory was the occurrence of innumerable organisms, apparently at least, indicative of design. To get over this difficulty, Haeckel says, some who could not believe in a creative and controlling mind adopted the idea of a metaphysical ghost called vitality. The grand service rendered by Darwin to science is, that his theory enables us to account for the appearances of design in nature without assuming final causes, or, a mind working for a foreseen and intended end. "All that had appeared before Darwin," he says, "failed to secure success, and to meet with general acceptance of the doctrine of the mechanical production of vegetable and animal organisms. This was accomplished by Darwin's theory." (p. 20) The precise difficulty which Mr. Darwin's doctrine has, according to Haeckel, enabled men of science to surmount, is thus clearly stated on p. 633. It is, "that organs for a definite end should be produced by undesigning or mechanical causes." This difficulty is overcome by the doctrine of evolution. "Through the theory of descent, we are for the first time able to establish the monistic doctrine of the unity of nature, that a mechanic-causal explanation of the most complicated organisms, _e. g._ the formation and constitution of the organs of sense, have no more difficulty for the common understanding, than the mechanical explanation of any physical process, as, for example, earthquakes, the direction of the winds, or the currents of the sea. We thus arrive at the conviction of the last importance, that all natural bodies with which we are acquainted are equally endowed with life (gleichmässig belebt sind); that the distinction between living and dead matter does not exist. When a stone is thrown into the air and falls by certain laws to the ground, or when a solution of salt forms a crystal, the result is neither more nor less a mechanical manifestation of life, than the flowering of a plant, the generation or sensibility of animals, or the feelings or the mental activity of man. In thus establishing the monistic theory of nature lies the highest and most comprehensive merit of the doctrine of descent, as reformed by Darwin." (p. 21) "As to the much vaunted design in nature, it is a reality only for those whose views of animal and vegetable life are to the last degree superficial. Any one who has gone deeper into the organization and vital activity of animals and plants, who has made himself familiar with the action and reaction of vital phenomena, and the so-called economy of nature, comes of necessity to the conclusion, that design does not exist, any more than the vaunted goodness of the Creator" (die vielgerühmte Allgüte des Schöpfers). (p. 17) Professor Huxley, in his review of this work of Haeckel, already quoted, says: "I do not like to conclude without reminding the reader of my entire concurrence with the general tenor and spirit of the work, and of my high estimate of its value." If you take out of Haeckel's book its doctrine of Monism, which he himself says means Materialism, it has no "tenor or spirit" in it. It is not, however, for us to say how far Professor Huxley intended his indorsement to go. Haeckel says that Darwin's theory of evolution leads inevitably to Atheism and Materialism. In this we think he is correct. But we have nothing to do with Haeckel's logic or with our own. We make no charge against Mr. Darwin. We cite Haeckel merely as a witness to the fact that Darwinism involves the denial of final causes; that it excludes all intelligent design in the production of the organs of plants and animals, and even in the production of the soul and body of man. This first of German naturalists would occupy a strange position in the sight of all Europe, if, after lauding a book to the skies because it teaches a certain doctrine, it should turn out that the book taught no such doctrine at all. FOOTNOTES: [29] _The Science of Nature versus the Science of Man_. By Noah Porter, President of Yale College. New York, 1871, p. 29. [30] _Natürlische Schöpfungsgeschichte_. Von Dr. Ernst Haeckel, Professor in der Universität Jena. Zweite Auflage, Berlin, 1873, pp. 8, and 9. _The Opponents of Darwinism._ _The Duke of Argyll._ When cultivated men undertake to refute a certain system, it is to be presumed that they give themselves the trouble to ascertain what that system is. As the advocates of Mr. Darwin's theory defend and applaud it because it excludes design, and as its opponents make that the main ground of their objection to it, there can be no reasonable doubt as to its real character. The question is, How are the contrivances in nature to be accounted for? One answer is, They are due to the purpose of God. Mr. Darwin says, They are due to the gradual and undesigned accumulation of slight variations. The Duke's first objection to that doctrine is, that the evidence of design in the organs of plants and animals is so clear that Mr. Darwin himself cannot avoid using teleological language. "He exhausts," he says, "every form of words and of illustration by which intention or mental purpose can be described. 'Contrivance,' 'beautiful contrivance,' 'curious contrivance,' are expressions which occur over and over again. Here is one sentence describing a particular species (of orchids): 'The labellum is developed _in order_ to attract the Lepidoptera; and we shall soon see reason for supposing that the nectar is purposely so lodged, that it can be sucked only slowly _in order_ to give time for the curious chemical quality of the matter setting hard and dry.'"[31] We have already seen that Mr. Darwin's answer to this objection is, that it is hard to keep from personifying nature, and that these expressions as used by him mean no more than chemists mean when they speak of affinities, and one element preferring another. A second objection is, that a variation would not be useful to the individual in which it happens to occur, unless other variations should occur at the right time and in the right order; and that the concurrence of so many accidents as are required to account for the infinite diversity of forms in plants and animals, is altogether inconceivable. A third objection is, that the variations often have no reference to the organism of the animal itself but to other organisms. "Take one instance," he says, "out of millions. The poison of a deadly snake,--let us for a moment consider what that is. It is a secretion of definite chemical properties with reference not only--not even mainly--to the organism of the animal in which it is developed, but specially to another animal which it is intended to destroy." "How," he asks, "will the law of growth adjust a poison in one animal with such subtle knowledge of the organization of the other, that the deadly virus shall in a few minutes curdle the blood, benumb the nerves, and rush in upon the citadel of life? There is but one explanation: a Mind having minute and perfect knowledge of the structure of both has designed the one to be capable of inflicting death upon the other. This mental purpose and resolve is the one thing which our intelligence perceives with direct and intuitive recognition. The method of creation by which this purpose has been carried into effect is utterly unknown."[32] A fourth objection has reference to beauty. According to Mr. Darwin, flowers are not intentionally made beautiful, but those which happen to be beautiful attract insects, and by their agency are fertilized and survive. Male birds are not intentionally arrayed in bright colors, but those which happen to be so arrayed are attractive, and thus become the progenitors of their race. Against this explanation the Duke earnestly protests. He refers to the gorgeous adorned class of Hummingbirds, of which naturalists enumerate no less than four hundred and thirty different species, distinguished one from the other, in general, only by their plumage. "Now," he asks, "what explanation does the law of natural selection give,--I will not say of the origin, but even of the continuance of such specific varieties as these? None whatever. A crest of topaz is no better in the struggle of existence than a crest of sapphire. A frill ending in spangles of the emerald is no better in the battle of life than a frill ending in spangles of the ruby. A tail is not affected for the purposes of flight, whether its marginal, or its central feathers are decorated with white. It is impossible to bring such varieties into any physical law known to us. It has relation however to a Purpose, which stands in close analogy with our knowledge of purpose in the works of men. Mere beauty and mere variety, for their own sake, are objects which we ourselves seek, when we can make the forces of nature subordinate to the attainment of them. There seems to be no conceivable reason why we should doubt or question that these are ends and aims also in the forms given to living organisms, when the facts correspond with this view and with no other."[33] It will be observed that all these objections have reference to the denial of teleology on the part of Mr. Darwin. If his theory admitted that the organisms in nature were due to a divine purpose, the objections would be void of all meaning. There is a fifth objection. According to Darwin's theory organs are formed by the slow accumulation of unintended variations, which happen to be favorable to the subject of them in the struggle for life. But in many cases these organs, instead of being favorable, are injurious or cumbersome until fully developed. Take the wing of a bird, for example. In its rudimental state, it is useful neither for swimming, walking, nor flying. Now, as Darwin says it took millions of years to bring the eye to perfection, how long did it take to render a rudimental wing useful? It is no sufficient answer to say that these rudimental organs might have been suited to the condition in which the animal existed, during the formative process. This is perfectly arbitrary. It has no basis of fact. There are but three kinds of locomotion that we know of: in the water, on the ground, and through the air; for all these purposes a half-formed wing would be an impediment. The Duke devotes almost a whole chapter of his interesting book to the consideration of "contrivance in the machinery for flight." The conditions to secure regulated movement through the atmosphere are so numerous, so complicated, and so conflicting, that the problem never has been solved by human ingenuity. In the structure of the bird it is solved to perfection. As we are not writing a teleological argument, but only producing evidence that Darwinism excludes teleology, we cannot follow the details which prove that the wing of the gannet or swift is almost as wonderful and beautiful a specimen of contrivance as the eye of the eagle. FOOTNOTES: [31] _Reign of Law_. London, 1867, p. 40. [32] _Reign of Law_. London, 1867, p. 37. [33] _Reign of Law_, pp. 247, 248. _Agassiz._ Every one knows that the illustrious Agassiz, over whose recent grave the world stands weeping, was from the beginning a pronounced and earnest opponent of Mr. Darwin's theory. He wrote as a naturalist, and therefore his objections are principally directed against the theory of evolution, which he regarded as not only destitute of any scientific basis, but as subversive of the best established facts in zoölogy. Nevertheless it is evident that his zeal was greatly intensified by his apprehension that a theory which obliterates all evidence of the being of God from the works of nature, endangered faith in that great doctrine itself. The Rev. Dr. Peabody, in the discourse delivered on the occasion of Professor Agassiz's funeral, said: "I cannot close this hasty and inadequate, yet fervent and hearty tribute, without recalling to your memory the reverent spirit in which he pursued his scientific labors. Nearly forty years ago, in his first great work on fossil fishes, in developing principles of classification, he wrote in quotations, 'An invisible thread in all ages runs through this immense diversity, exhibiting as a general result that there is a continual progress in development ending in man, the four classes of vertebrates presenting the intermediate steps, and the invertebrates the constant accessory accompaniment. Have we not here the manifestation of a mind as powerful as prolific? an act of intelligence as sublime as provident? the marks of goodness as infinite as wise? the most palpable demonstration of the existence of a personal God, author of all this; ruler of the universe, and the dispenser of all good? This at least is what I read in the works of creation.' And it was what he ever read, and with profound awe and adoration. To this exalted faith he was inflexibly loyal. The laws of nature were to him the eternal Word of God. "His repugnance to Darwinism grew in great part from his apprehension of its atheistical tendency,--an apprehension which I confess I cannot share; for I forget not that these theories, now in the ascendent, are maintained by not a few devout Christian men, and while they appear to me unproved and incapable of demonstration, I could admit them without parting with one iota of my faith in God and Christ. Yet I cannot but sympathize most strongly with him in the spirit in which he resisted what seemed to him lese-majesty against the sovereign of the universe. Nor was his a theoretical faith. His whole life, in its broad philanthropy, in its pervading spirit of service, in its fidelity to arduous trusts and duties, and in its simplicity and truthfulness, bespoke one who was consciously fulfilling a mission from God to his fellow-men." The words "evolution" and "Darwinism" are so often in this country, but not in Europe, used interchangeably, that it is conceivable that Dr. Peabody could retain his faith in God, and yet admit the doctrine of evolution. But it is not conceivable that any man should adopt the main element of Mr. Darwin's theory, viz., the denial of all final causes, and the assertion, that since the first creation of matter and life, God has left the universe to the control of unintelligent physical causes, so that all the phenomena of the plants and animals, all that is in man, and all that has ever happened on the earth, is due to physical force, and yet retain his faith in Christ. On that theory, there have been no supernatural revelation, no miracles; Christ is not risen, and we are yet in our sins. It is not thus that this matter is regarded abroad. The Christians of Germany say that the only alternative these theories leave us, is Heathenism or Christianity; "Heidenthum oder Christenthum, Die Frage der Zeit." _Janet._ Janet, a professor of philosophy, is the author of a book on the Materialism of Büchner.[34] The greater part of the last chapter of his work is devoted to Darwinism. He says, "Dr. Büchner invoked (Darwin's book) as a striking confirmation of his doctrine." (p. 154) What Büchner's doctrine is has been shown on a previous page. The points of coincidence between Darwin's system and his are, that both regard mind as a mere function of living matter; and both refer all the organs and organisms of living things to the unconscious, unintelligent operation of physical causes. Büchner's way of accounting for complicated organs was, "that the energy of the elements and forces of matter, which in their fated and accidental occurrence must have produced innumerable forms, which must needs limit each other mutually, and correspond, apparently, the one with the other, as if they were made for that purpose. Out of all those forms, they only have survived which were adapted, in some manner, to the conditions of the medium in which they were placed." (p. 30) This is very clumsy. No wonder Büchner preferred Darwin's method. The two systems are, indeed, exactly the same, but Mr. Darwin has a much more winning way of presenting it. Professor Janet does not seem to have much objection to the doctrine of evolution in itself; it is the denial of teleology that he regards as the fatal element of Mr. Darwin's theory. "According to us," he says, "the true stumbling-block of Mr. Darwin's theory, the perilous and slippery point, is the passage from artificial to natural selection; it is when he wants to establish that a blind and designless nature has been able to obtain, by the occurrence of circumstances, the same results which man obtains by thoughtful and well calculated industry." (p. 174) Towards the end of his volume he says: "We shall conclude by a general observation. Notwithstanding the numerous objections we have raised against Mr. Darwin's theory, we do not declare ourselves hostile to a system of which zoölogists are the only competent judges. We are neither for nor against the transmutation of species, neither for nor against the principle of natural selection. The only positive conclusion of our debate is this: no principle hitherto known, neither the action of media, nor habit, nor natural selection, can account for organic adaptations without the intervention of the principle of finality. Natural selection, unguided, submitted to the laws of a pure mechanism, and exclusively determined by accidents, seems to me, under another name, the chance proclaimed by Epicurus, equally barren, equally incomprehensible; on the other hand, natural selection guided beforehand by a provident will, directed towards a precise end by intentional laws, might be the means which nature has selected to pass from one stage of being to another, from one form to another, to bring to perfection life throughout the universe, and to rise by a continuous process from the monad to man. Now, I ask Mr. Darwin himself, what interest has he in maintaining that natural selection is not guided--not directed? What interest has he in substituting accidental causes for every final cause? I cannot see. Let him admit that in natural, as well as in artificial selection, there may be a choice and direction; his principle immediately becomes much more fruitful than it was before. His hypothesis, then, whilst having the advantage of exempting science from the necessity of introducing the personal and miraculous intervention of God in the creation of each species, yet would be free from the banishing out of the universe an all-provident thought, and of submitting everything to blind and brute chance." (pp. 198, 199) Professor Janet asks far too much of Mr. Darwin. To ask him to give up his denial of final causes is like asking the Romanists to give up the Pope. That principle is the life and soul of his system. FOOTNOTE: [34] _The Materialism of the Present Day: a Critique of Dr. Büchner's System_. By Paul Janet, Member of the Institute of France, Professor of Philosophy at the Paris Faculté des Lettres. Translated from the French, by Gustave Masson, B. A. London and Paris, 1867. _M. Flourens._ M. Flourens, recently dead, was one of the earliest and most pronounced opponents of Darwinism. He published in 1864 his "Examen du Livre de M. Darwin sur l'Origine des Espèces." His position as Member of the Académie Française, and Perpetual Secretary of the Académie des Sciences, or Institut de France, vouch for his high rank among the French naturalists. His connection with the Jardin des Plantes gave him enlarged opportunities for biological experiments. The result of his own experience, as well as the experience of other observers, was, as he expresses it, his solemn conviction that species are fixed and not transmutable. No ingenuity of device could render hybrids fertile. "They never establish an intermediate species." It is, therefore, to the doctrine of evolution his attention is principally directed. Nevertheless, he is no less struck by Darwin's way of excluding all intelligence and design in his manner of speaking of nature. On this point he quotes the language of Cuvier, who says: "Nature has been personified. Living beings have been called the works of nature. The general bearing of these creatures to each other has become the laws of nature. It is thus while considering Nature as a being endowed with intelligence and will, but in its power limited and secondary, that it may be said that she watches incessantly over the maintenance of her work; that she does nothing in vain, and always acts by the most simple means.... It is easy to see how puerile are those who give nature a species of individual existence distinct from the Creator, and from the law which He has impressed upon the movements and peculiarities of the forms given by Him to living things, and which He makes to act upon their bodies with a peculiar force and reason." Older writers, says Flourens, in speaking of Nature, "gave to her inclinations, intentions, and views, and horrors (of a vacuum), and sports," etc. He says that one of the principal objects of his book is to show how Mr. Darwin "has deluded himself, and perhaps others, by a constant abuse of figurative language." "He plays with Nature as he pleases, and makes her do whatsoever he wishes." When we remember that Mr. Darwin defines Nature to be the aggregate of physical forces, we see how, in attributing everything to Nature, he effectually excludes the supernatural. In his volume of "Lay Sermons, Reviews," etc., Professor Huxley has a very severe critique on M. Flourens's book. He says little, however, in reference to teleology, except in one paragraph, in which we read: "M. Flourens cannot imagine an unconscious selection; it is for him a contradiction in terms." Huxley's answer is, "The winds and waves of the Bay of Biscay have not much consciousness, and yet they have with great care 'selected,' from an infinity of masses of silex, all grains of sand below a certain size and have heaped them by themselves over a great area.... A frosty night selects the hardy plants in a plantation from among the tender ones as effectually as if the intelligence of the gardener had been operative in cutting the weaker ones down."[35] If this means anything, it means that as the winds and waves of the Bay of Biscay can make heaps of sand, so similar unconscious agencies can, if you only give them time enough, make an elephant or a man; for this is what Mr. Darwin says natural selection has done. FOOTNOTE: [35] _Lay Sermons_, p. 347. _Rev. Walter Mitchell, M. A., Vice-President of the Victoria Institute._ The Victoria Institute, or Philosophical Society of Great Britain, under the presidency of the Earl of Shaftesbury, includes among its members many of the dignitaries of the Church of England, and a large number of distinguished men of different professions and denominations. Its principal object is, "To investigate fully and impartially the most important questions of philosophy and science, but more especially those that bear on the great truths revealed in Holy Scripture, with the view of defending these truths against the opposition of Science, falsely so called." The Institute holds bi-monthly meetings, at which papers are read on some important topic, and then submitted to criticism and discussion. These papers, many of which are very elaborate, are published in the Transactions of the Institute, together with a full report of the discussions to which they gave rise. Six volumes, replete with valuable and varied information, have already been published. Very considerable latitude of opinion is allowed. Hence we find in the Transactions, papers for and against evolution,--for and against Darwinism. It would be easy to quote extracts, pertinent to our subject, more than enough to fill a volume much larger than the present. We must content ourselves with a few citations from the discussion on a paper in favor of the credibility of Darwinism,[36] and another in favor of the doctrine of evolution.[37] In summing up the debates on these two topics, the chairman, Rev. Walter Mitchell, presented with great clearness and force his reasons for regarding Darwinism as incredible and impossible. In his protracted remarks he contrasts the Scriptural doctrine, that of the Vestiges of Creation, and that of Darwin on the origin of species. He thus states the doctrine of the Bible on the subject: "If," he says, "science be another name for real knowledge; if science be the pursuit of sound wisdom; if science be the pursuit of truth itself; I say that man has no right to reject anything that is true because it savors of God. Well, what is this hypothesis--older than that of Darwin--which does, and does alone, account for all the observed facts, or all that which we can read, recorded in the book of Nature? It is, that God created all things very good; that He made every vegetable after its own kind; that He made every animal after its own kind; that He allowed certain laws of variation, but that He has ordained strict, though invisible and invincible barriers, which prevent that variation from running riot, and which includes it within strict and well defined limits. This is a hypothesis which will account for all that we have learnt from the works of Nature. It admits an intelligent Being as the Author of all the works of creation, animate as well as inanimate; it leaves no mysteries in the animate world unaccounted for. There is one thing which the animate, as well as the inanimate world declares to man, one thing everywhere plainly recorded, if we will only read it, and that is the impress of design, the design of infinite wisdom. Any theory which comes in with an attempt to ignore design as manifested in God's creation, is a theory, I say, which attempts to dethrone God. This the theory of Darwin does endeavor to do. If asked how our old theory accounts for such uniformity of design in the midst of such perplexing variety as we find in nature, we reply, that this can only be accounted for on one admission, that the whole is the work of one Author, built according, as it were, to one style; that it represents the unity of one mind with the infinite power of adapting all its works in the most perfect manner for the uses for which they were created." "Whewell has boldly maintained, and he has never been controverted, that all real advances in the sciences of physiology and comparative anatomy,--such as that made by Harvey in discovering the circulation of the blood,--have been made by those who not only believed in the existence of design everywhere manifested in the animate world, but were led by that belief to make their discoveries." When discussing the paper of Mr. Henslow on evolution, he says: "In speaking of this paper I must commend the exceeding reverent tone in which the author has discussed the subject, and I should like to see all such subjects discussed in a similar tone. The view which Mr. Henslow brings forward, however, does not appear to be a very original one. It was the first view ever brought forward on the doctrine of evolution, and I was the first one to point out that the whole doctrine was one of retrograde character. The whole tone and character of this paper, except that which relates to the attributes and moral government of God,[38] is nothing more or less than the same view of the doctrine of evolution which created such a sensation in this country when that famous book came out, 'The Vestiges of Creation.' So far as I can understand the arguments of Mr. Darwin, they have simply been an endeavor to eject out of the idea of evolution the personal work of the Deity. His whole endeavor has been to push the Creator farther and farther back out of view. The most laborious part of Darwin's attempt at reasoning,--for it is not true reasoning,--the most laborious part of his logic and reasoning, is intended to eliminate, as perfectly as any of the atheistical authors have endeavored to do, the idea of design. Now, setting revelation aside, the manner in which the unknown author of the 'Vestiges of Creation' treated this subject, satisfactorily showed that the doctrine of evolution was not in itself an atheistical doctrine, nor did it deny the existence of design. So far as I could understand and make out, having carefully read the book at the time it came out and afterwards, and having carefully analyzed and compared it and Mr. Darwin's book with each other, so far as I could understand it, the doctrine of the author of the 'Vestiges of Creation' was simply, that God created all things, and that when He created matter He impressed on it certain laws; that matter, being evolved according to those laws, should produce beings and organs mutually adapted to one another and to the world; and that every successive development which should be produced was essentially foreseen, foreknown, and predetermined by the Deity. His idea, for instance, of the evolution of an eye from a more simple organ was that the ultimate eye--man's eye, for instance--was to be a perfect optical instrument, and that its perfection depended on the previous design by the Creator, that at a certain period it should appear in a body quite adapted for its purposes. There is one question,--and not the only one, but we must consider it as an important question,--whether you can maintain a doctrine of evolution which shall not be atheistical, and which shall admit the great argument of design? That is one thing; but the next thing is, does such a doctrine as that accord either with revelation or with the facts of science? I do not believe that it can be made to agree with what we believe to be the revealed Word of God, and I do not believe that it has in the least degree been proved that the doctrine is consistent with sound science." As to Mr. Darwin's theory, it is obvious from the passages already quoted that he considers its characteristic feature is not evolution, nor even natural selection, but the denial of teleology, or of intelligent control. Mr. Darwin admits the original creation of one or a few forms of life; and Mr. Mitchell, in his comments on Mr. Warington's defence of his theory, asks, "Why am I to limit the work of the Creator to the simultaneous or successive creations of ten or twelve commencements of the animate creation? Why, simply for the purpose of evading the evidence of design as manifested in the adaptation of all the organs of every animate creature to its wants, which can only be done by so incredible an hypothesis as that of Mr. Darwin. I say fearlessly, that any hypothesis which requires us to admit that the formation of such complex organs as the eye, the ear, the heart, the brain, with all their marvellous structures and mechanical adaptations to the wants of the creatures possessing them, so perfectly in harmony, too, with the laws of inorganic matter, affords no evidence of design; that such structures could be built up by gradual chance improvements, perpetuated by the law of transmission, and perfected by the destruction of creatures less favorably endowed, is so incredible, that I marvel to find any thinking man capable of adopting it for a single moment." It is useless to multiply quotations. Darwinism is never brought up either formally or incidentally, that its exclusion of design in the formation of living organisms is not urged as the main objection against the whole theory. FOOTNOTES: [36] _The Credibility of Darwinism_. By George Warington, Esq., F. C. S., M. V. I. [37] _On certain Analogies between the Methods of Deity in Nature and Revelation_. By Rev. G. E. Henslow, M. A., F. L. S., M. V. I. [38] The second part of Mr. Henslow's paper concerns "the methods of the Deity as revealed to us in the Bible." The same is substantially true of his work, _The Theory of Evolution_. _Principal Dawson._ Dr. Dawson, as we are informed, is regarded as the first palæontologist, and among the first geologists, in America. In his "Story of Earth and Man,"[39] he passes in review the several geological periods recognized by geologists; describes as far as knowable the distribution of land and water during each period, and the vegetable and animal productions by which they were distinguished. His book from beginning to end is anti-Darwinian. In common with other naturalists, his attention is directed principally to the doctrine of evolution, which he endeavors to prove is utterly untenable. That Mr. Darwin's theory excludes teleology is everywhere assumed as an uncontroverted and uncontrovertible fact. "The evolutionist doctrine," he says, "is itself one of the strangest phenomena of humanity. It existed, and most naturally, in the oldest philosophy and poetry, in connection with the crudest and most uncritical attempts of the human mind to grasp the system of nature; but that in our day a system destitute of any shadow of proof, and supported merely by vague analogies and figures of speech, and by the arbitrary and artificial coherence of its own parts, should be accepted as philosophy, and should find able adherents to string on its thread of hypotheses our vast and weighty stores of knowledge, is surpassingly strange.... In many respects these speculations are important, and worthy the attention of thinking men. They seek to revolutionize the religious belief of the world, and if accepted would destroy most of the existing theology and philosophy. They indicate tendencies among scientific thinkers, which, though probably temporary, must, before they disappear, descend to lower strata, and reproduce themselves in grosser forms, and with most serious effects on the whole structure of society. With one class of minds they constitute a sort of religion, which so far satisfies the craving for truth higher than those which relate to immediate wants and pleasures. With another and perhaps larger class, they are accepted as affording a welcome deliverance from all scruples of conscience and fears of a hereafter. In the domain of science evolutionism has like tendencies. It reduces the position of man, who becomes a descendant of inferior animals, and a mere term in a series whose end is unknown. It removes from the study of nature the ideas of final cause and purpose; and the evolutionist, instead of regarding the world as a work of consummate plan, skill, and adjustment, approaches nature as he would a chaos of fallen rocks, which may present forms of castles, and grotesque profiles of men and animals, but they are all fortuitous and without significance." (pp. 317, 318) "Taking, then, this broad view of the subject, two great leading alternatives are presented to us. Either man is an independent product of the will of a Higher Intelligence, acting directly or through the laws and materials of his own institution and production, or he has been produced by an unconscious evolution from lower things. It is true that many evolutionists, either unwilling to offend, or not perceiving the logical consequences of their own hypothesis, endeavor to steer a middle course, and to maintain that the Creator has proceeded by way of evolution. But the bare, hard logic of Spencer, the greatest English authority on evolution, leaves no place for this compromise, and shows that the theory, carried out to its legitimate consequences, excludes the knowledge of a Creator and the possibility of his work. We have, therefore, to choose between evolution and creation, bearing in mind, however, that there may be a place in nature for evolution, properly limited, as well as for other things, and that the idea of creation by no means excludes law and second causes." (p. 321) "It may be said, that evolution may be held as a scientific doctrine in connection with a modified belief in creation. The work of actual creation may have been limited to a few elementary types, and evolution may have done the rest. Evolutionists may still be theists. We have already seen that the doctrine, as carried out to its logical consequences, excludes creation and theism. It may, however, be shown that even in its more modified form, and when held by men who maintain that they are not atheists, it is practically atheistic, because excluding the idea of plan and design, and resolving all things into the action of unintelligent forces. It is necessary to observe this, because it is the half-way-evolutionism, which professes to have a creator somewhere behind it, that is most popular; though it is, if possible, more unphilosophical than that which professes to set out with absolute and determined nonentity, or from self-existing stardust containing all the possibilities of the universe." In reference to the objection of evolutionists, that the origin of every new species, on the theistic doctrine, supposes "a miracle," an intervention of the divine efficiency without the agency of second causes, Principal Dawson asks, "What is the actual statement of the theory of creation as it may be held by a modern man of science? Simply this: that all things have been produced by the Supreme Creative will, acting either directly, or through the agency of the forces and material of his own production." (p. 340) He thus sums up his argument against the doctrine of evolution, specially in its application to man: "Finally, the evolutionist picture wants some of the fairest lineaments of humanity, and cheats us with the semblance of man without the reality. Shave and paint your ape as you may, clothe him and set him up upon his feet, still he fails greatly of the 'human form divine;' and so it is with him morally and spiritually as well. We have seen that he wants the instinct of immortality, the love of God, the mental and spiritual power of exercising dominion over the earth. The very agency by which he is evolved is of itself subversive of all these higher properties; the struggle for existence is essentially selfish, and, therefore, degrading. Even in the lower animals, it is a false assumption that its tendency is to elevate; for animals, when driven to the utmost verge of the struggle for life, become depauperated and degraded. The dog which spends its life in snarling contention with its fellow curs for insufficient food, will not be a noble specimen of its race. God does not so treat his creatures. There is far more truth to nature in the doctrine which represents Him as listening to the young ravens when they cry for food. But as applied to man, the theory of the struggle for existence, and survival of the fittest, though the most popular phase of evolutionism at present, is nothing less than the basest and most horrible of superstitions. It makes man not merely carnal but devilish. It takes his lowest appetites and propensities, and makes them his God and Creator. His higher sentiments and aspirations, his self-denying philanthropy, his enthusiasm for the good and true, all the struggles and sufferings of heroes and martyrs, not to speak of that self-sacrifice which is the foundation of Christianity, are, in the view of the evolutionist, mere loss and waste, failure in the struggle of life. What does he give us in exchange? An endless pedigree of bestial ancestors, without one gleam of high and holy tradition to enliven the procession; and for the future, the prospect that the poor mass of protoplasm, which constitutes the sum of our being, and which is the sole gain of an indefinite struggle in the past, must soon be resolved again into inferior animals or dead matter. That men of thought and culture should advocate such a philosophy, argues either a strange mental hallucination, or that the higher spiritual nature has been wholly quenched within them. It is one of the saddest of many sad spectacles which our age presents." (p. 395) FOOTNOTE: [39] _The Story of Earth and Man_. By J. W. Dawson, LL. D., F. R. S., F. G. S., Principal and Vice-Chancellor of McGill University, Montreal. Author of _Archaia, Acadian Geology_, etc. Second edition. London, 1873, pp. 397. _Relation of Darwinism to Religion._ The consideration of that subject would lead into the wide field of the relation between science and religion. Into that field we lack competency and time to enter; a few remarks, however, on the subject may not be out of place. Those remarks, we would fain make in a humble way irenical. There is need of an Irenicum, for the fact is painfully notorious that there is an antagonism between scientific men as a class, and religious men as a class. Of course this opposition is neither felt nor expressed by all on either side. Nevertheless, whatever may be the cause of this antagonism, or whoever are to be blamed for it, there can be no doubt that it exists and that it is an evil. The first cause of the alienation in question is, that the two parties, so to speak, adopt different rules of evidence, and thus can hardly avoid arriving at different conclusions. To understand this we must determine what is meant by science, and by scientific evidence. Science, according to its etymology, is simply knowledge. But usage has limited its meaning, in the first place, not to the knowledge of facts or phenomena, merely, but to their causes and relations. It was said of old, "[Greek: hoti] scientiæ fundamentum, [Greek: dioti] fastigium." No amount of materials would constitute a building. They must be duly arranged so as to make a symmetrical whole. No amount of disconnected data can constitute a science. Those data must be systematized in their relation to each other and to other things. In the second place, the word is becoming more and more restricted to the knowledge of a particular class of facts, and of their relations, namely, the facts of nature or of the external world. This usage is not universal, nor is it fixed. In Germany, especially, the word _Wissenschaft_ is used of all kinds of ordered knowledge, whether transcendental or empirical. So we are accustomed to speak of mental, moral, social, as well as of natural science. Nevertheless, the more restricted use of the word is very common and very influential. It is important that this fact should be recognized. In common usage, a scientific man is distinguished specially from a metaphysician. The one investigates the phenomena of matter, the other studies the phenomena of mind, according to the old distinction between physics and metaphysics. Science, therefore, is the ordered knowledge of the phenomena which we recognize through the senses. A scientific fact is a fact perceived by the senses. Scientific evidence is evidence addressed to the senses. At one of the meetings of the Victoria Institute, a visitor avowed his disbelief in the existence of God. When asked, what kind of evidence would satisfy him? he answered, Just such evidence as I have of the existence of this tumbler which I now hold in my hand. The Rev. Mr. Henslow says, "By science is meant the investigation of facts and phenomena recognizable by the senses, and of the causes which have brought them into existence."[40] This is the main root of the trouble. If science be the knowledge of the facts perceived by the senses, and scientific evidence, evidence addressed to the senses, then the senses are the only sources of knowledge. Any conviction resting on any other ground than the testimony of the senses, must be faith. Darwin admits that the contrivances in nature may be accounted for by assuming that they are due to design on the part of God. But, he says, that would not be science. Haeckel says that to science matter is eternal. If any man chooses to say, it was created, well and good; but that is a matter of faith, and faith is imagination. Ulrici quotes a distinguished German physiologist who believes in vital, as distinguished from physical forces; but he holds to spontaneous generation, not, as he admits, because it has been proved, but because the admission of any higher power than nature is unscientific.[41] It is inevitable that minds addicted to scientific investigation should receive a strong bias to undervalue any other kind of evidence except that of the senses, _i. e._, scientific evidence. We have seen that those who give themselves up to this tendency come to deny God, to deny mind, to deny even self. It is true that the great majority of men, scientific as well as others, are so much under the control of the laws of their nature, that they cannot go to this extreme. The tendency, however, of a mind addicted to the consideration of one kind of evidence, to become more or less insensible to other kinds of proof, is undeniable. Thus even Agassiz, as a zoölogist and simply on zoölogical grounds, assumed that there were several zones between the Ganges and the Atlantic Ocean, each having its own flora and fauna, and inhabited by races of men, the same in kind, but of different origins. When told by the comparative philologists that this was impossible, because the languages spoken through that wide region, demonstrated that its inhabitants must have had a common descent, he could only answer that as ducks quack everywhere, he could not see why men should not everywhere speak the same language. A still more striking illustration is furnished by Dr. Lionel Beale, the distinguished English physiologist. He has written a book of three hundred and eighty-eight pages for the express purpose of proving that the phenomena of life, instinct, and intellect cannot be referred to any known natural forces. He avows his belief that in nature "mind governs matter," and "in the existence of a never-changing, all-seeing, power-directing and matter-guiding Omnipotence." He avows his faith in miracles, and "those miracles on which Christianity is founded." Nevertheless, his faith in all these points is provisional. He says that a truly scientific man, "if the maintenance, continuity, and nature of life on our planet should at some future time be fully explained without supposing the existence of any such supernatural omnipotent influence, would be bound to receive the new explanation, and might abandon the old conviction."[42] That is, all evidence of the truths of religion not founded on nature and perceived by the senses, amounts to nothing. Now as religion does not rest on the testimony of the senses, that is on scientific evidence, the tendency of scientific men is to ignore its claims. We speak only of tendency. We rejoice to know or believe that in hundreds or thousands of scientific men, this tendency is counteracted by their consciousness of manhood--the conviction that the body is not the man,--by the intuitions of the reason and the conscience, and by the grace of God. No class of men stands deservedly higher in public estimation than men of science, who, while remaining faithful to their higher nature, have enlarged our knowledge of the wonderful works of God. A second cause of the alienation between science and religion, is the failure to make the due distinction between facts and the explanation of those facts, or the theories deduced from them. No sound minded man disputes any scientific fact. Religious men believe with Agassiz that facts are sacred. They are revelations from God. Christians sacrifice to them, when duly authenticated, their most cherished convictions. That the earth moves, no religious man doubts. When Galileo made that great discovery, the Church was right in not yielding at once to the evidence of an experiment which it did not understand. But when the fact was clearly established, no man sets up his interpretation of the Bible in opposition to it. Religious men admit all the facts connected with our solar system; all the facts of geology, and of comparative anatomy, and of biology. Ought not this to satisfy scientific men? Must we also admit their explanations and inferences? If we admit that the human embryo passes through various phases, must we admit that man was once a fish, then a bird, then a dog, then an ape, and finally what he now is? If we admit the similarity of structure in all vertebrates, must we admit the evolution of one from another, and all from a primordial germ? It is to be remembered that the facts are from God, the explanation from men; and the two are often as far apart as Heaven and its antipode. These human explanations are not only without authority, but they are very mutable. They change not only from generation to generation, but almost as often as the phases of the moon. It is a fact that the planets move. Once it was said that they were moved by spirits, then by vortexes, now by self-evolved forces. It is hard that we should be called upon to change our faith with every new moon. The same man sometimes propounds theories almost as rapidly as the changes of the kaleidoscope. The amiable Sir Charles Lyell, England's most distinguished geologist, has published ten editions of his "Principles of Geology," which so differ as to make it hard to believe that it is the work of the same mind. "In all the editions up to the tenth, he looked upon geological facts and geological phenomena as proving the fixity of species and their special creation in time. In the tenth edition, just published, he announces his change of opinion on this subject and his conversion to the doctrine of development by law."[43] "In the eighth edition of his work," says Dr. Bree, "Sir Charles Lyell, the Nestor of geologists, to whom the present generation is more indebted than to any other for all that is known of geology in its advanced stage, teaches that species have a real existence in nature, and that each was endowed at the time of its creation with the attributes and organization by which it is now distinguished." The change on the part of this eminent geologist, it is to be observed, is a mere change of opinion. There was no change of the facts of geology between the publication of the eighth and of the tenth edition of his work, neither was there any change in his knowledge of those facts. All the facts relied upon by evolutionists, have long been familiar to scientific men. The whole change is a subjective one. One year the veteran geologist thinks the facts teach one thing, another year he thinks they teach another. It is now the fact, and it is feared it will continue to be a fact, that scientific men give the name of science to their explanations as well as to the facts. Nay, they are often, and naturally, more zealous for their explanations than they are for the facts. The facts are God's, the explanations are their own. The third cause of the alienation between religion and science, is the bearing of scientific men towards the men of culture who do not belong to their own class. When we, in such connections, speak of scientific men, we do not mean men of science as such, but those only who avow or manifest their hostility to religion. There is an assumption of superiority, and often a manifestation of contempt. Those who call their logic or their conjectures into question, are stigmatized as narrow-minded, bigots, old women, Bible worshippers, etc. Professor Huxley's advice to metaphysicians and theologians is, to let science alone. This is his Irenicum. But do he and his associates let metaphysics and religion alone? They tell the metaphysician that his vocation is gone; there is no such thing as mind, and of course no mental laws to be established. Metaphysics are merged into physics. Professor Huxley tells the religious world that there is over-whelming and crushing evidence (scientific evidence, of course) that no event has ever occurred on this earth which was not the effect of natural causes. Hence there have been no miracles, and Christ is not risen.[44] He says that the doctrine that belief in a personal God is necessary to any religion worthy of the name, is a mere matter of opinion. Tyndall, Carpenter, and Henry Thompson, teach that prayer is a superstitious absurdity; Herbert Spencer, whom they call their "great philosopher," _i. e._, the man who does their thinking, labors to prove that there cannot be a personal God, or human soul or self; that moral laws are mere "generalizations of utility," or, as Carl Vogt says, that self respect, and not the will of God, is the ground and rule of moral obligation. If any protest be made against such doctrines, we are told that scientific truth cannot be put down by denunciation (or as Vogt says, by barking). So doubtless the Pharisees, when our blessed Lord called them hypocrites and a generation of vipers, and said: "Ye compass sea and land to make one proselyte; and when he is made, ye make him twofold more the child of hell than yourselves," doubtless thought that that was a poor way to refute their theory, that holiness and salvation were to be secured by church-membership and church-rites. Nevertheless, as those words were the words of Christ, they were a thunderbolt which reverberates through all time and space, and still makes Pharisees of every name and nation tremble. Huxley's Irenicum will not do. Men who are assiduously poisoning the fountains of religion, morality, and social order, cannot be let alone. Haeckel's Irenicum amounts to much the same as that of Professor Huxley. He forbids the right to speak on these vital subjects, to all who are not thoroughly versed in biology, and who are not entirely emancipated from the trammels of their long cherished traditional beliefs.[45] This, as the whole context shows, means that a man in order to be entitled to be heard on the evolution theory, must be willing to renounce his faith not only in the Bible, but in God, in the soul, in a future life, and become a monistic materialist.[46] It is very reasonable that scientific men, in common with lawyers and physicians and other professional men, should feel themselves entitled to be heard with special deference on subjects belonging to their respective departments. This deference no one is disposed to deny to men of science. But it is to be remembered that no department of human knowledge is isolated. One runs into and overlaps another. We have abundant evidence that the devotees of natural science are not willing to confine themselves to the department of nature, in the common sense of that word. They not only speculate, but dogmatize, on the highest questions of philosophy, morality, and religion. And further, admitting the special claims to deference on the part of scientific men, other men have their rights. They have the right to judge of the consistency of the assertions of men of science and of the logic of their reasoning. They have the right to set off the testimony of one or more experts against the testimony of others; and especially, they have the right to reject all speculations, hypotheses, and theories, which come in conflict with well established truths. It is ground of profound gratitude to God that He has given to the human mind intuitions which are infallible, laws of belief which men cannot disregard any more than the laws of nature, and also convictions produced by the Spirit of God which no sophistry of man can weaken. These are barriers which no man can pass without plunging into the abyss of outer darkness. If there be any truth in the preceding remarks, then it is obvious that there can be no harmony between science and religion until the evils referred to be removed. Scientific men must come to recognize practically, and not merely in words, that there are other kinds of evidence of truth than the testimony of the senses. They must come to give due weight to the testimony of consciousness, and to the intuitions of the reason and conscience. They must cease to require the deference due to established facts to be paid to their speculations and explanations. And they must treat their fellow-men with due respect. The Pharisees said to the man whose sight had been restored by Christ, "Thou wast altogether born in sin, and dost thou teach us!" Men of science must not speak thus. They must not say to every objector, Thou art not scientific, and therefore hast no right to speak. The true Irenicum is for all parties to give due heed to such words as these, "If any man would be wise, let him become a fool, that he may be wise;" or these, "Be converted, and become as little children;" or these, "The Spirit of Truth shall guide you in all truth." We are willing to hear this called cant. Nevertheless, these latter words fell from the lips of Him who spake as never man spake. So much, and it is very little, on the general question of the relation of science to religion. But what is to be thought of the special relation of Mr. Darwin's theory to the truths of natural and revealed religion? We have already seen that Darwinism includes the three elements, evolution, natural selection, and the denial of design in nature. These points, however, cannot now be considered separately. It is conceded that a man may be an evolutionist and yet not be an atheist and may admit of design in nature. But we cannot see how the theory of evolution can be reconciled with the declarations of the Scriptures. Others may see it, and be able to reconcile their allegiance to science with their allegiance to the Bible. Professor Huxley, as we have seen, pronounces the thing impossible. As all error is antagonistic to truth, if the evolution theory be false, it must be opposed to the truths of religion so far as the two come into contact. Mr. Henslow, indeed, says Science and Religion are not antagonistic because they are in different spheres of thought. This is often said by men who do not admit that there is any thought at all in religion; that it is merely a matter of feeling. The fact, however, is that religion is a system of knowledge, as well as a state of feeling. The truths on which all religion is founded are drawn within the domain of science, the nature of the first cause, its relation to the world, the nature of second causes, the origin of life, anthropology, including the origin, nature, and destiny of man. Religion has to fight for its life against a large class of scientific men. All attempts to prevent her exercising her right to be heard are unreasonable and vain. It should be premised that this paper was written for the single purpose of answering the question, What is Darwinism? The discussion of the merits of the theory was not within the scope of the writer. What follows, therefore, is to be considered only in the light of a practical conclusion. 1. The first objection to the theory is its _primâ facie_ incredibility. That a single plant or animal should be developed from a mere cell, is such a wonder, that nothing but daily observation of the fact could induce any man to believe it. Let any one ask himself, suppose this fact was not thus familiar, what amount of speculation, of arguments from analogies, possibilities, and probabilities, could avail to produce conviction of its truth. But who can believe that all the plants and animals which have ever existed upon the face of the earth, have been evolved from one such germ? This is Darwin's doctrine. We are aware that this apparent impossibility is evaded by the believers in spontaneous generation, who hold that such germ cells may be produced anywhere and at all times. But this is not Darwinism. Darwin wants us to believe that all living things, from the lowly violet to the giant redwoods of California, from the microscopic animalcule to the Mastodon, the Dinotherium,--monsters the very description of which fill us with horror,--bats with wings twenty feet in breadth, flying dragons, tortoises ten feet high and eighteen feet long, etc., etc., came one and all from the same primordial germ. This demand is the more unreasonable when we remember that these living creatures are not only so different, but are, as to plants and animals, directly opposed in their functions. The function of the plant, as biologists express it, is to produce force, that of the animal to expend it. The plant, in virtue of a power peculiar to itself, which no art or skill of man can imitate, transmutes dead inorganic matter into organic matter, suited to the sustenance of animal life, and without which animals cannot live. The gulf, therefore, between the plant and animal would seem to be impassable. Further, the variations by which the change of species is effected are so trifling as often to be imperceptible, and their accumulation of them so slow as to evade notice,--the time requisite to accomplish any marked change must be counted by millions, or milliards of years. Here is another demand on our credulity. The apex is reached when we are told that all these transmutations are effected by chance, that is, without purpose or intention. Taking all these things into consideration, we think it may, with moderation, be said, that a more absolutely incredible theory was never propounded for acceptance among men. 2. There is no pretence that the theory can be proved. Mr. Darwin does not pretend to prove it. He admits that all the facts in the case can be accounted for on the assumption of divine purpose and control. All that he claims for his theory is that it is possible. His mode of arguing is that if we suppose this and that, then it may have happened thus and so. Amiable and attractive as the man presents himself in his writings, it rouses indignation, in one class at least of his readers, to see him by such a mode of arguing reaching conclusions which are subversive of the fundamental truths of religion. 3. Another fact cannot fail to attract attention. When the theory of evolution was propounded in 1844 in the "Vestiges of Creation," it was universally rejected; when proposed by Mr. Darwin, less than twenty years afterward, it was received with acclamation. Why is this? The facts are now what they were then. They were as well known then as they are now. The theory, so far as evolution is concerned, was then just what it is now. How then is it, that what was scientifically false in 1844 is scientifically true in 1864? When a drama is introduced in a theatre and universally condemned, and a little while afterward, with a little change in the scenery, it is received with rapturous applause, the natural conclusion is, that the change is in the audience and not in the drama. There is only one cause for the fact referred to, that we can think of. The "Vestiges of Creation" did not expressly or effectually exclude design. Darwin does. This is a reason assigned by the most zealous advocates of his theory for their adoption of it. This is the reason given by Büchner, by Haeckel, and by Vogt. It is assigned also in express terms by Strauss, the announcement of whose death has diffused a feeling of sadness over all who were acquainted with his antecedents. In his last work, "The Old Faith and the New," he admits "that Darwin's doctrine is a mere hypothesis; that it leaves the main points unexplained (Die Hupt und Cardinal-punkte noch unerklärt sind); nevertheless, as he has shown how miracles may be excluded, he is to be applauded as one of the greatest benefactors of the human race." (p. 177) By "Wunder," or miracle, Strauss means any event for which natural causes are insufficient to account. "We philosophers and critical theologians," he says, "have spoken well when we decreed the abolition of miracles; but our decree (macht-spruch) remained without effect, because we could not show them to be unnecessary, inasmuch as we were unable to indicate any natural force to take their place. Darwin has provided or indicated this natural force, this process of nature; he has opened the door through which a happier posterity may eject miracles forever." Then follows the sentence just quoted, "He who knows what hangs on miracle, will applaud Darwin as one of the greatest benefactors of the human race." With Strauss and others of his class, miracles and design are identical, because one as well as the other assumes supernatural agency. He quotes Helmholtz, who says, "Darwin's theory, that adaptation in the formation of organisms may arise without the intervention of intelligence, by the blind operation of natural law;" and then adds, "As Helmholtz distinguishes the English naturalist as the man who has banished design from nature, so we have praised him as the man who has done away with miracles. Both mean the same thing.[47] Design is the miracle-worker in nature, which has put the world upside down; or as Spinoza says, has placed the last first, the effect for the cause, and thus destroyed the very idea of nature. Design in nature, especially in the department of living organisms, has ever been appealed to by those who desire to prove that the world is not self-evolved, but the work of an intelligent Creator." (p. 211) On page 175, he refers to those who ridicule Darwin, and yet are so far under the influence of the spirit of the age as to deny miracles or the intervention of the Creator in the course of nature, and says: "Very well; how do they account for the origin of man, and in general the development of the organic out of the inorganic? Would they assume that the original man as such, no matter how rough and unformed, but still a man, sprang immediately out of the inorganic, out of the sea or the slime of the Nile? They would hardly venture to say that; then they must know that there is only the choice between miracle, the divine hand of the Creator, and Darwin." What an alternative; the Creator or Darwin! In this, however, Strauss is right. To banish design from nature, as is done by Darwin's theory, is, in the language of the Rev. Walter Mitchell, virtually "to dethrone the Creator." Ludwig Weis, M. D., of Darmstadt, says it is at present "the mode" in Germany (and of course in a measure here), to glorify Buddhism. Strauss, he adds, says, "Nature knows itself in man, and in that he expresses the thought which all Idealism and all Materialism make the grand end. To the same effect it is said, 'In Man the All comprehends itself as conscious being (comes to self-consciousness); or, in Man the absolute knowledge (Wissen, the act of knowing) appears in the limits of personality.' This was the doctrine of the Buddhist and of the ancient Chinese." Thus, as Dr. Weis says, "in the nineteenth century of the Christian era, philosophers and scientists have reached the point where the Chinese were two thousand years ago." The only way that is apparent for accounting for evolution being rejected in 1844, and for its becoming a popular doctrine in 1866, is, that it happens to suit a prevailing state of mind. It is a fact, so far as our limited knowledge extends, that no one is willing to acknowledge himself, not simply an evolutionist, but an evolutionist of the Darwinian school, who is not either a Materialist by profession, or a disciple of Herbert Spencer, or an advocate of the philosophy of Hume. There is another significant fact which goes to prove that the denial of design, which is the "creative idea" of Darwinism, is the main cause of its popularity and success. Professor Owen, England's greatest naturalist, is a derivationist. Derivation and evolution are convertible terms. Both include the denial that species are primordial, or have each a different origin; and both imply that one species is formed out of another and simpler form. Professor Owen, however, although a derivationist, or evolutionist, is a very strenuous anti-Darwinian. He differs from Darwin as to two points. First, as to Natural Selection, or the Survival of the Fittest. He says that is inconsistent with facts and utterly insufficient to account for the origin of species. He refers the origin of species to an inherent tendency to change impressed on them from the beginning. And second, he admits design. He denies that the succession and origin of species are due to chance, and expresses his belief in the constant operation of creative power in the formation of species from the varied descendants of more generalized forms.[48] He believes "that all living things have been produced by such law (of variation) in time, their position and uses in the world having been preordained by the Creator."[49] Professor Owen says he has taught the doctrine of derivation (evolution) for thirty years, but it attracted little attention. As soon, however, as Darwin leaves out design, we have a prairie-fire. A prairie-fire, happily, does not continue very long; and while it lasts, it burns up little else than stubble. 4. All the evidence we have in favor of the fixedness of species is, of course, evidence not only against Darwinism, but against evolution in all its forms. It would seem idle to discuss the question of the mutability of species, until satisfied what species is. This, unhappily, is a question which it is exceedingly difficult to answer. Not only do the definitions given by scientific men differ almost indefinitely, but there is endless diversity in classification. Think of four hundred and eighty species of humming-birds. Haeckel says that one naturalist makes ten, another forty, another two hundred, and another one, species of a certain fossil; and we have just heard that Agassiz had collected eight hundred species of the same fossil animal. Haeckel also says (p. 246), that there are no two zoölogists or any two botanists who agree altogether in their classification. Mr. Darwin says, "No clear line of demarcation has yet been drawn between species and sub-species, and varieties." (p. 61) It is absolutely necessary, therefore, that a distinction should be made between artificial and natural species. No man asserts the immutability of all those varieties of plants and animals, which naturalists, for the convenience of classification, may call distinct species. Haeckel, for example, gives a list of twelve species of man. So any one may make fifty species of dogs, or of horses. This is a mere artificial distinction, which amounts to nothing. There is far greater difference between a pouter and a carrier pigeon, than between a Caucasian and a Mongolian. To call the former varieties of the same species, and the latter distinct species, is altogether arbitrary. Nevertheless, notwithstanding the arbitrary classifications of naturalists, it remains true that there are what Professor Dana calls "units" of the organic world. "When individuals multiply from generation to generation, it is but a repetition of the primordial type-idea, and the true notion of the species is not in the resulting group, but in the idea or potential element which is the basis of every individual of the group."[50] Dr. Morton's definition of species as "primordial organic forms," agrees with that given by Professor Dana; and both agree with the Bible, which says that God created plants and animals each after its kind. A primordial form is a form which was not evolved out of some other form, but which began to be in the form--subject to such varieties as we see in the dog, horse, and man--in which it continued during the whole period of its existence. The criteria of these primordial forms or species of nature, are, (1.) Morphological. Animals, however, may approach very nearly in their structure, and yet belong to different species. It is only when the peculiarities of structure are indicative of specialty of design, that they form a safe ground of classification. If the teeth of one animal are formed to fit it to feed on flesh, and those of another to fit it to feed on plants; if one has webbed feet and another not; then, in all such cases, difference of structure proves difference of kind. (2.) Physiological; that is, the internal nature, indicated by habits and instincts, furnishes another safe criterion. (3.) Permanent fecundity. The progenitors of the same species reproduce their kind from generation to generation; the progeny of different species, although nearly allied, do not. It is a fixed law of nature that species never can be annihilated, except by all the individuals included in them dying out; and that new species cannot be produced. Every true species is primordial. It is this fact, that is, that no variety, with the essential characteristics of species, has ever been produced, that forces, as we saw above, Professor Huxley to pronounce Mr. Darwin's doctrine to be an unproved hypothesis. Species continue; varieties, if let alone, always revert to the normal type. It requires the skill and constant attention of man to keep them distinct. Now that there are such forms in nature, is proved not only from the testimony of the great body of the most distinguished naturalists, but by all the facts in the case. First, the fact that such species are known to have existed unchanged, through what geologists consider almost immeasurable periods of time. Palæontologists tell us that Trilobites abounded from the primordial age down to the Carboniferous period, that is, as they suppose, through millions of years. More wonderful still, the little animals whose remains constitute the chalk formations which are spread over large areas of country, and are sometimes a hundred feet thick, are now at work at the bottom of the Atlantic. Principal Dawson tells us, with regard to Mollusks existing in a sub-fossil state in the Post-pliocene clays of Canada, that "after carefully studying about two hundred species, and of some of these, many hundreds of specimens, I have arrived at the conclusion that they are absolutely unchanged.... Here again we have an absolute refusal, on the part of all these animals, to admit that they are derived, or have tended to sport into new species."[51] On the previous page he says, "Pictet catalogues ninety-eight species of mammals which inhabited Europe in the Post-glacial period. Of these fifty-seven still exist unchanged, and the remainder have disappeared. Not one can be shown to have been modified into a new form, though some of them have been obliged, by changes of temperature and other conditions, to remove into distant and now widely separated regions." A second fact which attests the primordial character and fixedness of species is, that every species as it first appears, is not in a transition state between one form and another, but in the perfection of its kind. Science has indeed discovered an ascending order in creation, which agrees marvellously with that given in the book of Genesis: first, vegetable productions; then the moving creatures in the sea; then terrestrial animals; and finally man. Naturalists, who utterly reject the Scriptures as a divine revelation, speak with the highest admiration of the Mosaic account of the creation, as compared with any other cosmogony of the ancient world. While there is in general an ascending series in these living forms, each was perfect in its kind. Agassiz says that fishes existed contemporaneously with species of all the invertebrate sub-kingdoms in the Taconic, or sub-Cambrian strata. This is the extreme limit of known geological strata in which life is found to have existed. As the evolution of one species out of another requires, according to Darwin, millions of years, it is out of the question to trace these animals beyond the strata in which their remains are now found. Yet "crabs or lobsters, worms, cuttle-fish, snails, jelly-fish, star-fish, oysters, the polyps lived contemporaneously with the first known vertebrate animals that ever came into being--all as clearly defined by unmistakable ordinal or special characters as they are at the present moment."[52] The foot of the horse is considered by zoölogists as "one of the most beautiful contrivances in nature." The remains of this animal found in what is called the Pliocene Period, show the foot to have been as perfect then as it is now. Mr. Wallace says that man has existed on the earth a hundred thousand years, and that it is probable that he existed four hundred thousand years ago. Of course we do not believe this. We have little faith in the chronology of science. It gives no sure data for the calculation of time, hence we find them differing from four thousand to four hundred thousand years as to the time required for certain formations. The most trustworthy geologists teach that all that is known of the antiquity of man falls within the limits of Biblical chronology. The further, however, Darwinians push back the origin of man, the stronger, as against them, becomes the argument for the immutability of species. The earliest remains of man show that at his first appearance, he was in perfection. The oldest known human skull is that called the "Engis," because found in the cave of Engis in Belgium. Of this skull Professor Huxley says it may have belonged to an individual of one of the existing races of men. Principal Dawson, who has a cast of it, on the same shelf with the skulls of some Algonquin Indians, says it might be taken for the skull of an American Indian. Indeed, Dawson seems to think that these fossil human remains go to show that the earliest men were better developed than any of the extant races. Thirdly. The historical evidence accessible all goes to prove the immutability of species. The earliest historical records and the oldest monuments prove that all extant animals were what they now are thousands of years ago. Fourthly. The fact that hybrids cannot be perpetuated, that no device of man can produce a new species, is proof that God has fixed limits which cannot be passed. This Huxley himself admits to be an insuperable objection. So long as it exists, he says, Darwin's doctrine must be content to remain a hypothesis; it cannot pretend to the dignity of a theory. Another fact of like import is that varieties artificially produced, if let alone, uniformly revert to the simple typical form. It is only by the utmost care they can be kept distinct. All the highly prized varieties of horses, cattle, sheep, pigeons, etc., without human control, would be merged each class into one, with only the slight differences occasioned by diversities of climate and other external conditions. If in the sight of man it is important that the words of a book should be kept distinct, it is equally evident that in the sight of God it is no less important that the "units of nature" should not be mixed in inextricable and indistinguishable confusion. Fifthly. The sudden appearance of new kinds of animals is another fact which Palæontologists urge against the doctrine of evolution. According to the view of geologists great changes have, at remote periods, occurred in the state of the earth. Continents have been submerged and the bottom of the sea raised above the surface of the waters. Corresponding changes have occurred in the state of the atmosphere surrounding the globe, and in the temperature of the earth. Accompanying or following these revolutions new classes of plants and animals appear, adapted to the new condition of the earth's surface. Whence do they come? They have, as Dawson expresses it, neither fathers nor mothers. Nothing precedes them from which they could be derived; and nothing of the same kind follows them. They live through their appointed period; and then, in a multitude of cases, finally disappear, and are in their turn followed by new orders or kinds. In other words, the links or connecting forms of this assumed regular succession or derivation are not to be found. This fact is so patent, that Hugh Miller, when arguing against the doctrine of evolution as proposed in the "Vestiges of Creation," says, that the record in the rocks seems to have been written for the very purpose of proving that such evolution is impossible. We have the explicit testimony of Agassiz, as a Palæontologist, that the facts of geology contradict the theory of the transmutation of species. This testimony has been repeatedly given and in various forms. In the last production of his pen, he says: "As a Palæontologist I have from the beginning stood aloof from this new theory of transmutation, now so widely admitted by the scientific world. Its doctrines, in fact, contradict what the animal forms buried in the rocky strata of our earth tell us of their own introduction and succession upon the surface of the globe." "Let us look now at the earliest vertebrates, as known and recorded in geological surveys. They should, of course, if there is any truth in the transmutation theory, correspond with the lowest in rank or standing. What then are the earliest known vertebrates? They are Selachians (sharks and their allies) and Ganoids (garpikes and the like), the highest of all living fishes, structurally speaking." He closes the article from which these quotations are taken with the assertion, "that there is no evidence of a direct descent of later from earlier species in the geological succession of animals."[53] It will be observed that Agassiz is quoted, not as to matters of theory, but as to matters of fact. The only answer which evolutionists can make to this argument, is the imperfection of the geological record. When asked, Where are the immediate predecessors of these new species? they answer, They have disappeared, or, have not yet been found. When asked, Where are their immediate successors? the answer again is, They have disappeared.[54] This is an objection which Mr. Darwin, with his usual candor, virtually admits to be unanswerable. We have already seen, that he says, "Every one will admit that the geological record is imperfect; but very few can believe that it is so very imperfect as my theory demands." Such are some of the grounds on which geologists and palæontologists of the highest rank assert that the theory of evolution has not the slightest scientific basis; and they support their assertion with an amount of evidence of which the above items are a miserable pittance. Sixthly. There is another consideration of decisive importance. Strauss says, there are three things which have been stumbling-blocks in the way of science. First, the origin of life; second, the origin of consciousness; third, the origin of reason. These are equivalent to the gaps which, Principal Dawson says, exist in the theory of evolution. He states them thus: 1. That between dead and living matter. 2. That between vegetable and animal life. "These are necessarily the converse of each other: the one deoxidizes and accumulates, the other oxidizes and expends." 3. That "between any species of plant or animal, and any other species. It was this gap, and this only, which Darwin undertook to fill up by his great work on the origin of species, but, notwithstanding the immense amount of material thus expended, it yawns as wide as ever, since it must be admitted that no case has been ascertained in which an individual of one species has transgressed the limits between it and another species." 4. "Another gap is between the nature of the animal and the self-conscious, reasoning, and moral nature of man." (pp. 325-328) First, as to the gap between death and life; this is what Dr. Stirling calls the "gulf of all gulfs, which Mr. Huxley's protoplasm is as powerless to efface as any other material expedient that has ever been suggested."[55] This gulf Mr. Darwin does not attempt to bridge over. He admits that life owes its origin to the act of the Creator. This, however, the most prominent of the advocates of Darwinism say, is giving up the whole controversy. If you admit the intervention of creative power at one point, you may as well admit it in any other. If life owes its origin to creative power, why not species? If the stupendous miracle of creation be admitted, there is no show of reason for denying supernatural intervention in the operations of nature. Most Darwinians attempt to pass this gulf on the imaginary bridge of spontaneous generation. In other words, they say there is no gulf there. The molecules of matter, in one combination, may as well exhibit the phenomena of life, as in other combinations, any other kind of phenomena. The distinguished Sir William Thomson cannot trust himself to that bridge. "Dead matter," he says, "cannot become living matter without coming under the influence of matter previously alive. This seems to me as sure a teaching of science as the law of gravitation.... I am ready to adopt, as an article of scientific faith, true through all space and through all time, that life proceeds from life, and nothing but life."[56] He refers the origin of life on this earth to falling meteors, which bring with them from other planets the germs of living organisms; and from those germs all the plants and animals with which our world is now covered have been derived. Principal Dawson thinks that this was intended as irony. But the whole tone of the address, and specially of the closing portion of it, in which this idea is advanced, is far too serious to admit of such an explanation. No one can read the address referred to without being impressed, and even awed, by the immensity and grandeur of the field of knowledge which falls legitimately within the domain of science. The perusal of that discourse produces a feeling of humility analogous to the sense of insignificance which every man experiences when he thinks of himself as a speck on the surface of the earth, which itself is but a speck in the immensity of the universe. And when a man of mere ordinary culture sees Sir William Thomson surveying that field with a mastery of its details and familiarity with all the recondite methods of its investigation, he feels as nothing in his presence. Yet this great man, whom we cannot help regarding with wonder, is so carried away by the spirit of his class as to say, "Science is bound, by the everlasting law of honor, to face fearlessly every problem which can fairly be brought before it. If a probable solution, consistent with the ordinary course of nature, can be found, we must not invoke an abnormal act of Creative Power." And, therefore, instead of invoking Creative Power, he accounts for the origin of life on earth by falling meteors. How he accounts for its origin in the places whence the meteors came, he does not say. Yet Sir William Thomson believes in Creative Power; and in a subsequent page, we shall quote his explicit repudiation of the atheistic element in the Darwinian theory. Strauss quotes Dubois-Reymond, a distinguished naturalist, as teaching that the first of these great problems, viz. the origin of life, admits of explanation on scientific (i. e., in his sense, materialistic) principles; and even the third, viz. the origin of reason; but the second, or the origin of consciousness, he says, "is perfectly inscrutable." Dubois-Reymond holds that "the most accurate knowledge of the essential organism reveals to us only matter in motion; but between this material movement and my feeling pain or pleasure, experiencing a sweet taste, seeing red, with the conclusion 'therefore I exist,' there is a profound gulf; and it 'remains utterly and forever inconceivable why to a number of atoms of carbon, hydrogen, etc., it should not be a matter of indifference how they lie or how they move; nor, can we in any wise tell how consciousness should result from their concurrent action.' Whether," adds Strauss, "these _Verba Magistri_ are indeed the last word on the subject, time only can tell."[57] But if it is inconceivable, not to say absurd, that sense-consciousness should consist in the motion of molecules of matter, or be a function of such molecules, it can hardly be less absurd to account for thought, conscience, and religious feeling and belief on any such hypothesis. It may be said that Mr. Darwin is not responsible for these extreme opinions. That is very true. Mr. Darwin is not a Monist, for in admitting creation, he admits a dualism as between God and the world. Neither is he a Materialist, inasmuch as he assumes a supernatural origin for the infinitesimal modicum of life and intelligence in the primordial animalcule, from which without divine purpose or agency, all living things in the whole history of our earth have descended. All the innumerable varieties of plants, all the countless forms of animals, with all their instincts and faculties, all the varieties of men with their intellectual endowments, and their moral and religious nature, have, according to Darwin, been evolved by the agency of the blind, unconscious laws of nature. This infinitesimal spark of supernaturalism in Mr. Darwin's theory, would inevitably have gone out of itself, had it not been rudely and contemptuously trodden out by his bolder, and more logical successors. The grand and fatal objection to Darwinism is this exclusion of design in the origin of species, or the production of living organisms. By design is meant the intelligent and voluntary selection of an end, and the intelligent and voluntary choice, application, and control of means appropriate to the accomplishment of that end. That design, therefore, implies intelligence, is involved in its very nature. No man can perceive this adaptation of means to the accomplishment of a preconceived end, without experiencing an irresistible conviction that it is the work of mind. No man does doubt it, and no man can doubt it. Darwin does not deny it. Haeckel does not deny it. No Darwinian denies it. What they do is to deny that there is any design in nature. It is merely apparent, as when the wind of the Bay of Biscay, as Huxley says, "selects the right kind of sand and spreads it in heaps upon the plains." But in thus denying design in nature, these writers array against themselves the intuitive perceptions and irresistible convictions of all mankind,--a barrier which no man has ever been able to surmount. Sir William Thomson, in the address already referred to, says: "I feel profoundly convinced that the argument of design has been greatly too much lost sight of in recent zoölogical speculations. Reaction against the frivolities of teleology, such as are to be found, not rarely, in the notes of the learned commentators on 'Paley's Natural Theology,' has, I believe, had a temporary effect of turning attention from the solid irrefragable argument so well put forward in that excellent old book. But overpowering proof of intelligence and benevolent design lie all around us, and if ever perplexities, whether metaphysical or scientific, turn us away from them for a time, they come back upon us with irresistible force, showing to us through nature the influence of a free will, and teaching us that all living beings depend upon one ever-acting Creator and Ruler." It is impossible for even Mr. Darwin, inconsistent as it is with his whole theory, to deny all design in the constitution of nature. What is his law of heredity? Why should like beget like? Take two germ cells, one of a plant, another of an animal; no man by microscope or by chemical analysis, or by the magic power of the spectroscope, can detect the slightest difference between them, yet the one infallibly develops into a plant and the other into an animal. Take the germ of a fish and of a bird, and they are equally indistinguishable; yet the one always under all conditions develops into a fish and the other into a bird. Why is this? There is no physical force, whether light, heat, electricity, or anything else, which makes the slightest approximation to accounting for that fact. To say, as Stuart Mill would say, that it is an ultimate fact, and needs no explanation, is to say that there may be an effect without an adequate cause. The venerable R. E. Von Baer, the first naturalist in Russia, of whom Agassiz speaks in terms of such affectionate veneration in the "Atlantic Monthly" for January, 1874, has written a volume dated Dorpat, 1873, and entitled "Zum Streit über den Darwinismus." In that volume, as we learn from a German periodical, the author says: "The Darwinians lay great stress on heredity; but what is the law of heredity but a determination of something future? Is it not in its nature in the highest degree teleological? Indeed, is not the whole faculty of reproduction intended to introduce a new life-process? When a man looks at a dissected insect and examines its strings of eggs, and asks, Whence are they? the naturalist of our day has no answer to give, but that they were of necessity gradually produced by the changes in matter. When it is further asked, Why are they there? is it wrong to say, It is _in order that_ when the eggs are mature and fertilized, new individuals of the same form should be produced." It is further to be considered that there are innumerable cases of contrivance, or evidence of design in nature, to which the principle of natural selection, or the purposeless changes effected by unconscious force, cannot apply; as for example, the distinction of sex, with all that is therein involved. But passing by such cases, it may be asked, what would it avail to get rid of design in the vegetable and animal kingdom, while the whole universe is full of it? That this ordered Cosmos is not from necessity or chance, is almost a self-evident fact. Not one man in a million of those who ever heard of God, either does doubt or can doubt it. Besides how are the cosmical relations of light, heat, electricity, to the constituent parts of the universe, and especially, so far as this earth is concerned, to vegetable and animal life, to be accounted for? Is this all chance work? Is it by chance that light and heat cause plants to carry on their wonderful operations, transmuting the inorganic into the organic, dead matter into living and life sustaining matter? Is it without a purpose that water instead of contracting, expands at the freezing point?--a fact to which is due that the earth north of the tropic is habitable for man or beast. It is no answer to this question to say that a few other substances have the same peculiarity, when no good end, that we can see, is thereby accomplished. No man is so foolish as to deny that his eye was intended to enable him to see, because he cannot tell what the spleen was made for. It is, however, useless to dwell upon this subject. If a man denies that there is design in nature, he can with quite as good reason deny that there is any design in any or in all the works ever executed by man. The conclusion of the whole matter is, that the denial of design in nature is virtually the denial of God. Mr. Darwin's theory does deny all design in nature, therefore, his theory is virtually atheistical; his theory, not he himself. He believes in a Creator. But when that Creator, millions on millions of ages ago, did something,--called matter and a living germ into existence,--and then abandoned the universe to itself to be controlled by chance and necessity, without any purpose on his part as to the result, or any intervention or guidance, then He is virtually consigned, so far as we are concerned, to non-existence. It has already been said that the most extreme of Mr. Darwin's admirers adopt and laud his theory, for the special reason that it banishes God from the world; that it enables them to account for design without referring it to the purpose or agency of God. This is done expressly by Büchner, Haeckel, Vogt, and Strauss. The opponents of Darwinism direct their objections principally against this element of the doctrine. This, as was stated by Rev. Dr. Peabody, was the main ground of the earnest opposition of Agassiz to the theory. America's great botanist, Dr. Asa Gray, avows himself an evolutionist; but he is not a Darwinian. Of that point we have the clearest possible proof. Mr. Darwin, after explicitly denying that the variations which have resulted in "the formation of the most perfectly adapted animals in the world, man included, were intentionally and specially guided," adds: "However much we may wish it, we can hardly follow Professor Asa Gray in his belief 'that variation has been led along certain beneficial lines' like a stream 'along definite and useful lines of irrigation.'"[58] If Mr. Darwin does not agree with Dr. Gray, Dr. Gray does not agree with Mr. Darwin. It is as to the exclusion of design from the operations of nature that our American, differs from the English, naturalist. This is the vital point. The denial of final causes is the formative idea of Darwin's theory, and therefore no teleologist can be a Darwinian. Dr. Gray quotes from another writer the sentence, "It is a singular fact, that when we can find how anything is done, our first conclusion seems to be that God did not do it;" and then adds, "I agree with the writer that this first conclusion is premature and unworthy; I will add, deplorable. Through what faults of dogmatism on the one hand, and skepticism on the other, it came to be so thought, we need not here consider. Let us hope, and I confidently expect, that it is not to last; that the religious faith which survived without a shock the notion of the fixedness of the earth itself, may equally outlast the notion of the absolute fixedness of the species which inhabit it; that in the future, even more than in the past, faith in an _order_, which is the basis of science, will not--as it cannot reasonably--be dissevered from faith in an _Ordainer_, which is the basis of religion."[59] We thank God for that sentence. It is the concluding sentence of Dr. Gray's address as ex-President of "The American Association for the Advancement of Science," delivered August, 1872. Dr. Gray goes further. He says, "The proposition that the things and events in nature were not designed to be so, if logically carried out, is doubtless tantamount to atheism." Again, "To us, a fortuitous Cosmos is simply inconceivable. The alternative is a designed Cosmos.... If Mr. Darwin believes that the events which he supposes to have occurred and the results we behold around us were undirected and undesigned; or if the physicist believes that the natural forces to which he refers phenomena are uncaused and undirected, no argument is needed to show that such belief is atheistic."[60] We have thus arrived at the answer to our question, What is Darwinism? It is Atheism. This does not mean, as before said, that Mr. Darwin himself and all who adopt his views are atheists; but it means that his theory is atheistic; that the exclusion of design from nature is, as Dr. Gray says, tantamount to atheism. Among the last words of Strauss were these: "We demand for our universe the same piety which the devout man of old demanded for his God." "In the enormous machine of the universe, amid the incessant whirl and hiss of its jagged iron wheels, amid the deafening crash of its ponderous stamps and hammers, in the midst of this whole terrific commotion, man, a helpless and defenceless creature, finds himself placed, not secure for a moment that on an imprudent motion a wheel may not seize and rend him, or a hammer crush him to a powder. This sense of abandonment is at first something awful."[61] Among the last words of Paul were these: "I know whom I have believed, and am persuaded that He is able to keep that which I have committed unto Him against that day.... The time of my departure is at hand. I have fought a good fight, I have finished my course, I have kept the faith: henceforth there is laid up for me a crown of righteousness, which the Lord, the righteous judge, shall give me at that day: and not to me only, but unto all them also that love his appearing." FOOTNOTES: [40] _Science and Scripture not Antagonistic, because Distinct in their Spheres of Thought_. A Lecture, by Rev. George Henslow, M. A., F. L. S., F. G. S. London, 1873, p. 1. [41] _Gott und Natur_, p. 200. [42] _Protoplasm; or, Matter and Life._ By Lionel S. Beale, M. B., F. R. S. Third edition. London & Philadelphia, 1874, p. 345; and the whole chapter on Design. [43] _Fallacies in the Hypothesis of Mr. Darwin_, by C. R. Bree, M. D., F. Z. S. London, 1872, p. 290. [44] When Professor Huxley says, as quoted above, that he does not deny the possibility of miracles, he must use the word miracle in a sense peculiar to himself. [45] _Jenaer Literaturzeitung_, January 3, 1874. In this number there is a notice by Doctor Haeckel of two books,--_Descendenzlehre und Darwinismus_, von Oscar Schmidt, Leipzig, 1873; and _Die Fortschritte des Darwinismus_, von J. W. Spengel, Cöln and Leipzig, 1874; in which he says: "Erstens, um in Sachen der Descendenz-Theorie mitreden zu können, ein gewisser Grad von tieferer biologischer (sowohl morphologischer als physiologischer) Bildung unentbehrlich, den die meistzen von jenen Auctoren (the opposers of the theory) nicht besitzen. Zweitens ist für ein klares und zutreffendes Urtheil in diesem Sachen eine rücksichtslose Hingabe an vernunftgemässe Erkenntniss und eine dadurch bedingte Resignation auf uralte, liebgewordene und tief vererbte Vorurtheile erforderlich, zu welcher sich die wenigsten entschliesen können." [46] In his _Natürlische Schöpfungsgeschichte_, Haeckel is still more exclusive. When he comes to answer the objections to the evolution, or, as he commonly calls it, the descendence theory, he dismisses the objections derived from religion, as unworthy of notice, with the remark that all Glaube ist Aberglaube; all faith is superstition. The objections from _a priori_, or intuitive truths, are disposed of in an equally summary manner, by denying that there are any such truths, and asserting that all our knowledge is from the senses. The objection that so many distinguished naturalists reject the theory, he considers more at length. First, many have grown old in another way of thinking and cannot be expected to change. Second, many are collectors of facts, without studying their relations, or are destitute of the genius for generalization. No amount of material makes a building. Others, again, are specialists. It is not enough that a man should be versed in one department; he must be at home in all: in Botany, Zoölogy, Comparative Anatomy, Biology, Geology, and Palæontology. He must be able to survey the whole field. Fourthly, and mainly, naturalists are generally lamentably deficient in philosophical culture and in a philosophical spirit. "The immovable edifice of the true, monistic science, or what is the same thing, natural science, can only arise through the most intimate interaction and mutual interpenetration of philosophy and observation (Philosophie und Empirie)." pp. 638-641. It is only a select few, therefore, of learned and philosophical monistic materialists, who are entitled to be heard on questions of the highest moment to every individual man, and to human society. [47] This short but significant sentence is omitted in the excellent translation of Strauss's book, by Mathilde Blind, republished in New York, by Henry Holt & Company, 1873. [48] _The Fallacies of Darwinism_, by C. R. Bree, M. D., p. 308. [49] _The Fallacies of Darwinism_, p. 305. [50] _Bibliotheca Sacra_, 1857, p. 861. [51] _The Story of Earth and Man_, p. 358. [52] Dr. Bree, p. 275. We presume geologists differ in the terms which they use to designate strata. Agassiz calls the oldest containing fossil, the sub-Cambrian. Principal Dawson calls the oldest the Laurentian, and places the first vertebrates in the Silurian. This is of no moment as to the argument. The important fact is that each species is distinct as soon as it appears; and that many have remained to the present time. [53] _Atlantic Monthly_, January, 1874. [54] We have heard a story of a gentleman who gave an artist a commission for a historical painting, and suggested as the subject, the Passage of the Israelites over the Red Sea. In due time he was informed that his picture was finished, and was shown by the artist a large canvas painted red. "What is that?" he asked. "Why," says the artist, "that is the Red Sea." "But where are the Israelites?" "Oh, they have passed over." "And where are the Egyptians?" "They are under the sea." [55] _As Regards Protoplasm in Relation to Professor Huxley's Essay an the Physical Basis of Life_. By Dr. James H. Stirling. See, also, _Physiological Anatomy and Physiology of Man_, by L. S. Beale; also, _The Mystery of Life in Reply to Dr. Gull's Attack on the Theory of Vitality_. By L. S. Beale, M. D., 1871. [56] The address delivered by Sir William Thomson, as President of the British Association at its meeting in Edinburgh, 1871. [57] _The Old Faith and the New_. Prefatory Postscript, xxi. [58] _Variation of Plants and Animals under Domestication_. New York, 1868, vol. ii. pp. 515, 516. [59] _Proceedings of the American Association for the Advancement of Science_. Cambridge, 1873, p. 20. [60] The _Atlantic Monthly_ for October, 1860. The three articles in the July, August, and October numbers of the _Atlantic_, on this subject, have been reprinted with the name of Dr. Asa Gray as their author. [61] Strauss says that as he has arrived at the conclusion that there is no personal God, and no life after death, it would seem to follow that the question, Have we still a religion? "must be answered in the negative." But as he makes the essence of religion to consist in a sense of dependence, and as he felt himself to be helpless in the midst of this whirling universe, he had that much religion left. ADVERTISEMENTS _The Great Theological Work of the Age._ DR. HODGE'S THEOLOGY. Systematic Theology. By CHARLES HODGE, D.D., LL.D., of Princeton Theological Seminary. _Complete in three volumes 8vo, tinted paper. Price, vols. I. and II._, $4.50. _Vol. III._, $5. In these volumes are comprised the results of the life-long labors and investigations of one of the most eminent theologians of the age. The work covers the ground usually occupied by treatises on Systematic Theology, and adopts the commonly received divisions of the subject,--THEOLOGY, Vol. I.; ANTHROPOLOGY, Vol. II.; SOTERIOLOGY AND ESCHATOLOGY, Vol. III. 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The various topics are discussed with that close and keen analytical and logical power combined with that simplicity, lucidity, and strength of style which have already given Dr. HODGE a world-wide reputation as a controversialist and writer, and as an investigator of the great theological problems of the day. _Single copies, sent post-paid on receipt of the price._ SCRIBNER, ARMSTRONG & CO., 654 Broadway, New York EDINBURGH REVIEW.--"The BEST History of the Roman Republic." LONDON TIMES.--"BY FAR THE BEST History of the Decline and Fall of the Roman Commonwealth." THE History of Rome, FROM THE EARLIEST TIME TO THE PERIOD OF ITS DECLINE. By Dr. THEODOR MOMMSEN. Translated, with the author's sanction and additions, by the Rev. W. P. DICKSON, Regius Professor of Biblical Criticism in the University of Glasgow, late Classical Examiner in the University of St. Andrews. 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2354	----	NOTE ON THE RESEMBLANCES AND DIFFERENCES IN THE STRUCTURE AND THE DEVELOPMENT OF THE BRAIN IN MAN AND APES BY PROFESSOR T. H. HUXLEY, F.R.S. [This essay is taken from 'The Descent of Man and Selection in relation to Sex' by Charles Darwin where it appears at the end of Chapter VII which is also the end of Part I. Footnotes are numbered as they appear in 'The Descent of Man.'] The controversy respecting the nature and the extent of the differences in the structure of the brain in man and the apes, which arose some fifteen years ago, has not yet come to an end, though the subject matter of the dispute is, at present, totally different from what it was formerly. It was originally asserted and re-asserted, with singular pertinacity, that the brain of all the apes, even the highest, differs from that of man, in the absence of such conspicuous structures as the posterior lobes of the cerebral hemispheres, with the posterior cornu of the lateral ventricle and the hippocampus minor, contained in those lobes, which are so obvious in man. But the truth that the three structures in question are as well developed in apes' as in human brains, or even better; and that it is characteristic of all the Primates (if we exclude the Lemurs) to have these parts well developed, stands at present on as secure a basis as any proposition in comparative anatomy. Moreover, it is admitted by every one of the long series of anatomists who, of late years, have paid special attention to the arrangement of the complicated sulci and gyri which appear upon the surface of the cerebral hemispheres in man and the higher apes, that they are disposed after the very same pattern in him, as in them. Every principal gyrus and sulcus of a chimpanzee's brain is clearly represented in that of a man, so that the terminology which applies to the one answers for the other. On this point there is no difference of opinion. Some years since, Professor Bischoff published a memoir (70. 'Die Grosshirn-Windungen des Menschen;' 'Abhandlungen der K. Bayerischen Akademie,' B. x. 1868.) on the cerebral convolutions of man and apes; and as the purpose of my learned colleague was certainly not to diminish the value of the differences between apes and men in this respect, I am glad to make a citation from him. "That the apes, and especially the orang, chimpanzee and gorilla, come very close to man in their organisation, much nearer than to any other animal, is a well known fact, disputed by nobody. Looking at the matter from the point of view of organisation alone, no one probably would ever have disputed the view of Linnaeus, that man should be placed, merely as a peculiar species, at the head of the mammalia and of those apes. Both shew, in all their organs, so close an affinity, that the most exact anatomical investigation is needed in order to demonstrate those differences which really exist. So it is with the brains. The brains of man, the orang, the chimpanzee, the gorilla, in spite of all the important differences which they present, come very close to one another" (loc. cit. p. 101). There remains, then, no dispute as to the resemblance in fundamental characters, between the ape's brain and man's: nor any as to the wonderfully close similarity between the chimpanzee, orang and man, in even the details of the arrangement of the gyri and sulci of the cerebral hemispheres. Nor, turning to the differences between the brains of the highest apes and that of man, is there any serious question as to the nature and extent of these differences. It is admitted that the man's cerebral hemispheres are absolutely and relatively larger than those of the orang and chimpanzee; that his frontal lobes are less excavated by the upward protrusion of the roof of the orbits; that his gyri and sulci are, as a rule, less symmetrically disposed, and present a greater number of secondary plications. And it is admitted that, as a rule, in man, the temporo-occipital or "external perpendicular" fissure, which is usually so strongly marked a feature of the ape's brain is but faintly marked. But it is also clear, that none of these differences constitutes a sharp demarcation between the man's and the ape's brain. In respect to the external perpendicular fissure of Gratiolet, in the human brain for instance, Professor Turner remarks: (71. 'Convolutions of the Human Cerebrum Topographically Considered,' 1866, p. 12.) "In some brains it appears simply as an indentation of the margin of the hemisphere, but, in others, it extends for some distance more or less transversely outwards. I saw it in the right hemisphere of a female brain pass more than two inches outwards; and on another specimen, also the right hemisphere, it proceeded for four-tenths of an inch outwards, and then extended downwards, as far as the lower margin of the outer surface of the hemisphere. The imperfect definition of this fissure in the majority of human brains, as compared with its remarkable distinctness in the brain of most Quadrumana, is owing to the presence, in the former, of certain superficial, well marked, secondary convolutions which bridge it over and connect the parietal with the occipital lobe. The closer the first of these bridging gyri lies to the longitudinal fissure, the shorter is the external parieto-occipital fissure" (loc. cit. p. 12). The obliteration of the external perpendicular fissure of Gratiolet, therefore, is not a constant character of the human brain. On the other hand, its full development is not a constant character of the higher ape's brain. For, in the chimpanzee, the more or less extensive obliteration of the external perpendicular sulcus by "bridging convolutions," on one side or the other, has been noted over and over again by Prof. Rolleston, Mr. Marshall, M. Broca and Professor Turner. At the conclusion of a special paper on this subject the latter writes: (72. Notes more especially on the bridging convolutions in the Brain of the Chimpanzee, 'Proceedings of the Royal Society of Edinburgh,' 1865-6.) "The three specimens of the brain of a chimpanzee, just described, prove, that the generalisation which Gratiolet has attempted to draw of the complete absence of the first connecting convolution and the concealment of the second, as essentially characteristic features in the brain of this animal, is by no means universally applicable. In only one specimen did the brain, in these particulars, follow the law which Gratiolet has expressed. As regards the presence of the superior bridging convolution, I am inclined to think that it has existed in one hemisphere, at least, in a majority of the brains of this animal which have, up to this time, been figured or described. The superficial position of the second bridging convolution is evidently less frequent, and has as yet, I believe, only been seen in the brain (A) recorded in this communication. The asymmetrical arrangement in the convolutions of the two hemispheres, which previous observers have referred to in their descriptions, is also well illustrated in these specimens" (pp. 8, 9). Even were the presence of the temporo-occipital, or external perpendicular, sulcus, a mark of distinction between the higher apes and man, the value of such a distinctive character would be rendered very doubtful by the structure of the brain in the Platyrrhine apes. In fact, while the temporo-occipital is one of the most constant of sulci in the Catarrhine, or Old World, apes, it is never very strongly developed in the New World apes; it is absent in the smaller Platyrrhini; rudimentary in Pithecia (73. Flower, 'On the Anatomy of Pithecia Monachus,' 'Proceedings of the Zoological Society,' 1862.); and more or less obliterated by bridging convolutions in Ateles. A character which is thus variable within the limits of a single group can have no great taxonomic value. It is further established, that the degree of asymmetry of the convolution of the two sides in the human brain is subject to much individual variation; and that, in those individuals of the Bushman race who have been examined, the gyri and sulci of the two hemispheres are considerably less complicated and more symmetrical than in the European brain, while, in some individuals of the chimpanzee, their complexity and asymmetry become notable. This is particularly the case in the brain of a young male chimpanzee figured by M. Broca. ('L'ordre des Primates,' p. 165, fig. 11.) Again, as respects the question of absolute size, it is established that the difference between the largest and the smallest healthy human brain is greater than the difference between the smallest healthy human brain and the largest chimpanzee's or orang's brain. Moreover, there is one circumstance in which the orang's and chimpanzee's brains resemble man's, but in which they differ from the lower apes, and that is the presence of two corpora candicantia--the Cynomorpha having but one. In view of these facts I do not hesitate in this year 1874, to repeat and insist upon the proposition which I enunciated in 1863: (74. 'Man's Place in Nature,' p. 102.) "So far as cerebral structure goes, therefore, it is clear that man differs less from the chimpanzee or the orang, than these do even from the monkeys, and that the difference between the brain of the chimpanzee and of man is almost insignificant when compared with that between the chimpanzee brain and that of a Lemur." In the paper to which I have referred, Professor Bischoff does not deny the second part of this statement, but he first makes the irrelevant remark that it is not wonderful if the brains of an orang and a Lemur are very different; and secondly, goes on to assert that, "If we successively compare the brain of a man with that of an orang; the brain of this with that of a chimpanzee; of this with that of a gorilla, and so on of a Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix, Lemur, Stenops, Hapale, we shall not meet with a greater, or even as great a, break in the degree of development of the convolutions, as we find between the brain of a man and that of an orang or chimpanzee." To which I reply, firstly, that whether this assertion be true or false, it has nothing whatever to do with the proposition enunciated in 'Man's Place in Nature,' which refers not to the development of the convolutions alone, but to the structure of the whole brain. If Professor Bischoff had taken the trouble to refer to p. 96 of the work he criticises, in fact, he would have found the following passage: "And it is a remarkable circumstance that though, so far as our present knowledge extends, there IS one true structural break in the series of forms of Simian brains, this hiatus does not lie between man and the manlike apes, but between the lower and the lowest Simians, or in other words, between the Old and New World apes and monkeys and the Lemurs. Every Lemur which has yet been examined, in fact, has its cerebellum partially visible from above; and its posterior lobe, with the contained posterior cornu and hippocampus minor, more or less rudimentary. Every marmoset, American monkey, Old World monkey, baboon or manlike ape, on the contrary, has its cerebellum entirely hidden, posteriorly, by the cerebral lobes, and possesses a large posterior cornu with a well-developed hippocampus minor." This statement was a strictly accurate account of what was known when it was made; and it does not appear to me to be more than apparently weakened by the subsequent discovery of the relatively small development of the posterior lobes in the Siamang and in the Howling monkey. Notwithstanding the exceptional brevity of the posterior lobes in these two species, no one will pretend that their brains, in the slightest degree, approach those of the Lemurs. And if, instead of putting Hapale out of its natural place, as Professor Bischoff most unaccountably does, we write the series of animals he has chosen to mention as follows: Homo, Pithecus, Troglodytes, Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the great break in this series lies between Hapale and Lemur, and that this break is considerably greater than that between any other two terms of that series. Professor Bischoff ignores the fact that long before he wrote, Gratiolet had suggested the separation of the Lemurs from the other Primates on the very ground of the difference in their cerebral characters; and that Professor Flower had made the following observations in the course of his description of the brain of the Javan Loris: (75. 'Transactions of the Zoological Society,' vol. v. 1862.) "And it is especially remarkable that, in the development of the posterior lobes, there is no approximation to the Lemurine, short hemisphered brain, in those monkeys which are commonly supposed to approach this family in other respects, viz. the lower members of the Platyrrhine group." So far as the structure of the adult brain is concerned, then, the very considerable additions to our knowledge, which have been made by the researches of so many investigators, during the past ten years, fully justify the statement which I made in 1863. But it has been said, that, admitting the similarity between the adult brains of man and apes, they are nevertheless, in reality, widely different, because they exhibit fundamental differences in the mode of their development. No one would be more ready than I to admit the force of this argument, if such fundamental differences of development really exist. But I deny that they do exist. On the contrary, there is a fundamental agreement in the development of the brain in men and apes. Gratiolet originated the statement that there is a fundamental difference in the development of the brains of apes and that of man--consisting in this; that, in the apes, the sulci which first make their appearance are situated on the posterior region of the cerebral hemispheres, while, in the human foetus, the sulci first become visible on the frontal lobes. (76. "Chez tous les singes, les plis posterieurs se developpent les premiers; les plis anterieurs se developpent plus tard, aussi la vertebre occipitale et la parietale sont-elles relativement tres-grandes chez le foetus. L'Homme presente une exception remarquable quant a l'epoque de l'apparition des plis frontaux, qui sont les premiers indiques; mais le developpement general du lobe frontal, envisage seulement par rapport a son volume, suit les memes lois que dans les singes:" Gratiolet, 'Memoire sur les plis cerebres de l'Homme et des Primateaux,' p. 39, Tab. iv, fig. 3.) This general statement is based upon two observations, the one of a Gibbon almost ready to be born, in which the posterior gyri were "well developed," while those of the frontal lobes were "hardly indicated" (77. Gratiolet's words are (loc. cit. p. 39): "Dans le foetus dont il s'agit les plis cerebraux posterieurs sont bien developpes, tandis que les plis du lobe frontal sont a peine indiques." The figure, however (Pl. iv, fig. 3), shews the fissure of Rolando, and one of the frontal sulci plainly enough. Nevertheless, M. Alix, in his 'Notice sur les travaux anthropologiques de Gratiolet' ('Mem. de la Societe d'Anthropologie de Paris,' 1868, page 32), writes thus: "Gratiolet a eu entre les mains le cerveau d'un foetus de Gibbon, singe eminemment superieur, et tellement rapproche de l'orang, que des naturalistes tres-competents l'ont range parmi les anthropoides. M. Huxley, par exemple, n'hesite pas sur ce point. Eh bien, c'est sur le cerveau d'un foetus de Gibbon que Gratiolet a vu LES CIRCONVOLUTIONS DU LOBE TEMPORO-SPHENOIDAL DEJA DEVELOPPEES LORSQU'IL N'EXISTENT PAS ENCORE DE PLIS SUR LE LOBE FRONTAL. Il etait donc bien autorise a dire que, chez l'homme les circonvolutions apparaissent d'a en w, tandis que chez les singes elles se developpent d'w en a."), and the other of a human foetus at the 22nd or 23rd week of uterogestation, in which Gratiolet notes that the insula was uncovered, but that nevertheless "des incisures sement de lobe anterieur, une scissure peu profonde indique la separation du lobe occipital, tres-reduit, d'ailleurs des cette epoque. Le reste de la surface cerebrale est encore absolument lisse." Three views of this brain are given in Plate II, figs. 1, 2, 3, of the work cited, shewing the upper, lateral and inferior views of the hemispheres, but not the inner view. It is worthy of note that the figure by no means bears out Gratiolet's description, inasmuch as the fissure (antero-temporal) on the posterior half of the face of the hemisphere is more marked than any of those vaguely indicated in the anterior half. If the figure is correct, it in no way justifies Gratiolet's conclusion: "Il y a donc entre ces cerveaux [those of a Callithrix and of a Gibbon] et celui du foetus humain une difference fondamental. Chez celui-ci, longtemps avant que les plis temporaux apparaissent, les plis frontaux, ESSAYENT d'exister." Since Gratiolet's time, however, the development of the gyri and sulci of the brain has been made the subject of renewed investigation by Schmidt, Bischoff, Pansch (78. 'Ueber die typische Anordnung der Furchen und Windungen auf den Grosshirn-Hemispharen des Menschen und der Affen,' 'Archiv fur Anthropologie,' iii. 1868.), and more particularly by Ecker (79. 'Zur Entwicklungs Geschichte der Furchen und Windungen der Grosshirn-Hemispharen im Foetus des Menschen.' 'Archiv fur Anthropologie,' iii. 1868.), whose work is not only the latest, but by far the most complete, memoir on the subject. The final results of their inquiries may be summed up as follows:-- 1. In the human foetus, the sylvian fissure is formed in the course of the third month of uterogestation. In this, and in the fourth month, the cerebral hemispheres are smooth and rounded (with the exception of the sylvian depression), and they project backwards far beyond the cerebellum. 2. The sulci, properly so called, begin to appear in the interval between the end of the fourth and the beginning of the sixth month of foetal life, but Ecker is careful to point out that, not only the time, but the order, of their appearance is subject to considerable individual variation. In no case, however, are either the frontal or the temporal sulci the earliest. The first which appears, in fact, lies on the inner face of the hemisphere (whence doubtless Gratiolet, who does not seem to have examined that face in his foetus, overlooked it), and is either the internal perpendicular (occipito-parietal), or the calcarine sulcus, these two being close together and eventually running into one another. As a rule the occipito-parietal is the earlier of the two. 3. At the latter part of this period, another sulcus, the "posterio-parietal," or "Fissure of Rolando" is developed, and it is followed, in the course of the sixth month, by the other principal sulci of the frontal, parietal, temporal and occipital lobes. There is, however, no clear evidence that one of these constantly appears before the other; and it is remarkable that, in the brain at the period described and figured by Ecker (loc. cit. pp. 212-213, Taf. II, figs. 1, 2, 3, 4), the antero-temporal sulcus (scissure parallele) so characteristic of the ape's brain, is as well, if not better developed than the fissure of Rolando, and is much more marked than the proper frontal sulci. Taking the facts as they now stand, it appears to me that the order of the appearance of the sulci and gyri in the foetal human brain is in perfect harmony with the general doctrine of evolution, and with the view that man has been evolved from some ape-like form; though there can be no doubt that form was, in many respects, different from any member of the Primates now living. Von Baer taught us, half a century ago, that, in the course of their development, allied animals put on at first, the characters of the greater groups to which they belong, and, by degrees, assume those which restrict them within the limits of their family, genus, and species; and he proved, at the same time, that no developmental stage of a higher animal is precisely similar to the adult condition of any lower animal. It is quite correct to say that a frog passes through the condition of a fish, inasmuch as at one period of its life the tadpole has all the characters of a fish, and if it went no further, would have to be grouped among fishes. But it is equally true that a tadpole is very different from any known fish. In like manner, the brain of a human foetus, at the fifth month, may correctly be said to be, not only the brain of an ape, but that of an Arctopithecine or marmoset-like ape; for its hemispheres, with their great posterior lobster, and with no sulci but the sylvian and the calcarine, present the characteristics found only in the group of the Arctopithecine Primates. But it is equally true, as Gratiolet remarks, that, in its widely open sylvian fissure, it differs from the brain of any actual marmoset. No doubt it would be much more similar to the brain of an advanced foetus of a marmoset. But we know nothing whatever of the development of the brain in the marmosets. In the Platyrrhini proper, the only observation with which I am acquainted is due to Pansch, who found in the brain of a foetal Cebus Apella, in addition to the sylvian fissure and the deep calcarine fissure, only a very shallow antero-temporal fissure (scissure parallele of Gratiolet). Now this fact, taken together with the circumstance that the antero-temporal sulcus is present in such Platyrrhini as the Saimiri, which present mere traces of sulci on the anterior half of the exterior of the cerebral hemispheres, or none at all, undoubtedly, so far as it goes, affords fair evidence in favour of Gratiolet's hypothesis, that the posterior sulci appear before the anterior, in the brains of the Platyrrhini. But, it by no means follows, that the rule which may hold good for the Platyrrhini extends to the Catarrhini. We have no information whatever respecting the development of the brain in the Cynomorpha; and, as regards the Anthropomorpha, nothing but the account of the brain of the Gibbon, near birth, already referred to. At the present moment there is not a shadow of evidence to shew that the sulci of a chimpanzee's, or orang's, brain do not appear in the same order as a man's. Gratiolet opens his preface with the aphorism: "Il est dangereux dans les sciences de conclure trop vite." I fear he must have forgotten this sound maxim by the time he had reached the discussion of the differences between men and apes, in the body of his work. No doubt, the excellent author of one of the most remarkable contributions to the just understanding of the mammalian brain which has ever been made, would have been the first to admit the insufficiency of his data had he lived to profit by the advance of inquiry. The misfortune is that his conclusions have been employed by persons incompetent to appreciate their foundation, as arguments in favour of obscurantism. (80. For example, M. l'Abbe Lecomte in his terrible pamphlet, 'Le Darwinisme et l'origine de l'Homme,' 1873.) But it is important to remark that, whether Gratiolet was right or wrong in his hypothesis respecting the relative order of appearance of the temporal and frontal sulci, the fact remains; that before either temporal or frontal sulci, appear, the foetal brain of man presents characters which are found only in the lowest group of the Primates (leaving out the Lemurs); and that this is exactly what we should expect to be the case, if man has resulted from the gradual modification of the same form as that from which the other Primates have sprung. 
16729	----	LAY SERMONS, ADDRESSES, AND REVIEWS by THOMAS HENRY HUXLEY, LL.D., F.R.S. London: MacMillan and Co. London R. Clay, Sons, and Taylor, Printers, Bread Street Hill. 1870 A PREFATORY LETTER. MY DEAR TYNDALL, I should have liked to provide this collection of "Lay Sermons, Addresses, and Reviews," with a Dedication and a Preface. In the former, I should have asked you to allow me to associate your name with the book, chiefly on the ground that the oldest of the papers in it is a good deal younger than our friendship. In the latter, I intended to comment upon certain criticisms with which some of these Essays have been met. But, on turning the matter over in my mind, I began to fear that a formal dedication at the beginning of such a volume would look like a grand lodge in front of a set of cottages; while a complete defence of any of my old papers would simply amount to writing a new one--a labour for which I am, at present, by no means fit. The book must go forth, therefore, without any better substitute for either Dedication, or Preface, than this letter; before concluding which it is necessary for me to notify you, and any other reader, of two or three matters. The first is, that the oldest Essay of the whole, that "On the Educational Value of the Natural History Sciences," contains a view of the nature of the differences between living and not-living bodies out of which I have long since grown. Secondly, in the same paper, there is a statement concerning the method of the mathematical sciences, which, repeated and expanded elsewhere, brought upon me, during the meeting of the British Association at Exeter, the artillery of our eminent friend Professor Sylvester. No one knows better than you do, how readily I should defer to the opinion of so great a mathematician if the question at issue were really, as he seems to think it is, a mathematical one. But I submit, that the dictum of a mathematical athlete upon a difficult problem which mathematics offers to philosophy, has no more special weight, than the verdict of that great pedestrian Captain Barclay would have had, in settling a disputed point in the physiology of locomotion. The genius which sighs for new worlds to conquer beyond that surprising region in which "geometry, algebra, and the theory of numbers melt into one another like sunset tints, or the colours of a dying dolphin," may be of comparatively little service in the cold domain (mostly lighted by the moon, some say) of philosophy. And the more I think of it, the more does our friend seem to me to fall into the position of one of those "verständige Leute," about whom he makes so apt a quotation from Goethe. Surely he has not duly considered two points. The first, that I am in no way answerable for the origination of the doctrine he criticises: and the second, that if we are to employ the terms observation, induction, and experiment, in the sense in which he uses them, logic is as much an observational, inductive, and experimental science as mathematics; and that, I confess, appears to me to be a _reductio ad absurdum_ of his argument. Thirdly, the essay "On the Physical Basis of Life" was intended to contain a plain and untechnical statement of one of the great tendencies of modern biological thought, accompanied by a protest, from the philosophical side, against what is commonly called Materialism. The result of my well-meant efforts I find to be, that I am generally credited with having invented "protoplasm" in the interests of "materialism." My unlucky "Lay Sermon" has been attacked by microscopists, ignorant alike of Biology and Philosophy; by philosophers, not very learned in either Biology or Microscopy; by clergymen of several denominations; and by some few writers who have taken the trouble to understand the subject. I trust that these last will believe that I leave the essay unaltered from no want of respectful attention to all they have said. Fourthly, I wish to refer all who are interested in the topics discussed in my address on "Geological Reform," to the reply with which Sir William Thomson has honoured me. And, lastly, let me say that I reprint the review of "The Origin of Species" simply because it has been cited as mine by a late President of the Geological Society. If you find its phraseology, in some places, to be more vigorous than seems needful, recollect that it was written in the heat of our first battles over the Novum Organon of biology; that we were all ten years younger in those days; and last, but not least, that it was not published until it had been submitted to the revision of a friend for whose judgment I had then, as I have now, the greatest respect. Ever, my dear TYNDALL, Yours very faithfully, T.H. HUXLEY LONDON, _June 1870_. CONTENTS. I. PAGE ON THE ADVISABLENESS OF IMPROVING NATURAL KNOWLEDGE. (A Lay Sermon delivered in St. Martin's Hall, on the evening of Sunday, the 7th of January, 1866, and subsequently published in the _Fortnightly Review_) 3 II. EMANCIPATION--BLACK AND WHITE. (The _Reader_, May 20th, 1865) 23 III. A LIBERAL EDUCATION: AND WHERE TO FIND IT. (An Address to the South London Working Men's College, delivered on the 4th of January, 1868, and subsequently published in _Macmillan's Magazine_) 31 IV. SCIENTIFIC EDUCATION: NOTES OF AN AFTER-DINNER SPEECH. (Delivered before the Liverpool Philomathic Society in April 1869, and subsequently published in _Macmillan's Magazine_) 60 V. ON THE EDUCATIONAL VALUE OF THE NATURAL HISTORY SCIENCES. (An Address delivered at St. Martin's Hall, on the 22d July, 1854, and published as a pamphlet in that year) 80 VI. ON THE STUDY OF ZOOLOGY. (A Lecture delivered at the South Kensington Museum, in 1861, and subsequently published by the Department of Science and Art) 104 VII. ON THE PHYSICAL BASIS OF LIFE. (A Lay Sermon delivered in Edinburgh, on Sunday, the 8th of November, 1868, at the request of the late Rev. James Cranbrook; subsequently published in the _Fortnightly Review_) 132 VIII. THE SCIENTIFIC ASPECTS OF POSITIVISM. (A Reply to Mr. Congreve's Attack upon the preceding Paper. Published in the _Fortnightly Review._ 1869) 162 IX. ON A PIECE OF CHALK. (A Lecture delivered to the Working Men of Norwich, during the Meeting of the British Association, in 1868. Subsequently published in _Macmillan's Magazine_) 192 X. GEOLOGICAL CONTEMPORANEITY AND PERSISTENT TYPES OF LIFE. (The Anniversary Address to the Geological Society for 1862) 223 XI. GEOLOGICAL REFORM. (The Anniversary Address to the Geological Society for 1869) 251 XII. THE ORIGIN OF SPECIES. (The _Westminster Review_, April 1860) 280 XIII. CRITICISMS ON "THE ORIGIN OF SPECIES." (The _Natural History Review_, 1864) 328 XIV. ON DESCARTES' "DISCOURSE TOUCHING THE METHOD OF USING ONE'S REASON RIGHTLY AND OF SEEKING SCIENTIFIC TRUTH." (An Address to the Cambridge Young Men's Christian Society, delivered on the 24th of March, 1870, and subsequently published in _Macmillan's Magazine_) 351 LAY SERMONS, ADDRESSES, AND REVIEWS. I. ON THE ADVISABLENESS OF IMPROVING NATURAL KNOWLEDGE. This time two hundred years ago--in the beginning of January, 1666--those of our forefathers who inhabited this great and ancient city, took breath between the shocks of two fearful calamities, one not quite past, although its fury had abated; the other to come. Within a few yards of the very spot on which we are assembled, so the tradition runs, that painful and deadly malady, the plague, appeared in the latter months of 1664; and, though no new visitor, smote the people of England, and especially of her capital, with a violence unknown before, in the course of the following year. The hand of a master has pictured what happened in those dismal months; and in that truest of fictions, "The History of the Plague Year," Defoe shows death, with every accompaniment of pain and terror, stalking through the narrow streets of old London, and changing their busy hum into a silence broken only by the wailing of the mourners of fifty thousand dead; by the woful denunciations and mad prayers of fanatics; and by the madder yells of despairing profligates. But, about this time in 1666, the death-rate had sunk to nearly its ordinary amount; a case of plague occurred only here and there, and the richer citizens who had flown from the pest had returned to their dwellings. The remnant of the people began to toil at the accustomed round of duty, or of pleasure; and the stream of city life bid fair to flow back along its old bed, with renewed and uninterrupted vigour. The newly kindled hope was deceitful. The great plague, indeed, returned no more; but what it had done for the Londoners, the great fire, which broke out in the autumn of 1666, did for London; and, in September of that year, a heap of ashes and the indestructible energy of the people were all that remained of the glory of five-sixths of the city within the walls. Our forefathers had their own ways of accounting for each of these calamities. They submitted to the plague in humility and in penitence, for they believed it to be the judgment of God. But, towards the fire they were furiously indignant, interpreting it as the effect of the malice of man,--as the work of the Republicans, or of the Papists, according as their prepossessions ran in favour of loyalty or of Puritanism. It would, I fancy, have fared but ill with one who, standing where I now stand, in what was then a thickly peopled and fashionable part of London, should have broached to our ancestors the doctrine which I now propound to you--that all their hypotheses were alike wrong; that the plague was no more, in their sense, Divine judgment, than the fire was the work of any political, or of any religious, sect; but that they were themselves the authors of both plague and fire, and that they must look to themselves to prevent the recurrence of calamities, to all appearance so peculiarly beyond the reach of human control--so evidently the result of the wrath of God, or of the craft and subtlety of an enemy. And one may picture to oneself how harmoniously the holy cursing of the Puritan of that day would have chimed in with the unholy cursing and the crackling wit of the Rochesters and Sedleys, and with the revilings of the political fanatics, if my imaginary plain dealer had gone on to say that, if the return of such misfortunes were ever rendered impossible, it would not be in virtue of the victory of the faith of Laud, or of that of Milton; and, as little, by the triumph of republicanism, as by that of monarchy. But that the one thing needful for compassing this end was, that the people of England should second the efforts of an insignificant corporation, the establishment of which, a few years before the epoch of the great plague and the great fire, had been as little noticed, as they were conspicuous. Some twenty years before the outbreak of the plague a few calm and thoughtful students banded themselves together for the purpose, as they phrased it, of "improving natural knowledge." The ends they proposed to attain cannot be stated more clearly than in the words of one of the founders of the organization:-- "Our business was (precluding matters of theology and state affairs) to discourse and consider of philosophical enquiries, and such as related thereunto:--as Physick, Anatomy, Geometry, Astronomy, Navigation, Staticks, Magneticks, Chymicks, Mechanicks, and Natural Experiments; with the state of these studies and their cultivation at home and abroad. We then discoursed of the circulation of the blood, the valves in the veins, the venæ lacteæ, the lymphatic vessels, the Copernican hypothesis, the nature of comets and new stars, the satellites of Jupiter, the oval shape (as it then appeared) of Saturn, the spots on the sun and its turning on its own axis, the inequalities and selenography of the moon, the several phases of Venus and Mercury, the improvement of telescopes and grinding of glasses for that purpose, the weight of air, the possibility or impossibility of vacuities and nature's abhorrence thereof, the Torricellian experiment in quicksilver, the descent of heavy bodies and the degree of acceleration therein, with divers other things of like nature, some of which were then but new discoveries, and others not so generally known and embraced as now they are; with other things appertaining to what hath been called the New Philosophy, which, from the times of Galileo at Florence, and Sir Francis Bacon (Lord Verulam) in England, hath been much cultivated in Italy, France, Germany, and other parts abroad, as well as with us in England." The learned Dr. Wallis, writing in 1696, narrates, in these words, what happened half a century before, or about 1645. The associates met at Oxford, in the rooms of Dr. Wilkins, who was destined to become a bishop; and subsequently coming together in London, they attracted the notice of the king. And it is a strange evidence of the taste for knowledge which the most obviously worthless of the Stuarts shared with his father and grandfather, that Charles the Second was not content with saying witty things about his philosophers, but did wise things with regard to them. For he not only bestowed upon them such attention as he could spare from his poodles and his mistresses, but, being in his usual state of impecuniosity, begged for them of the Duke of Ormond; and, that step being without effect, gave them Chelsea College, a charter, and a mace: crowning his favours in the best way they could be crowned, by burdening them no further with royal patronage or state interference. Thus it was that the half-dozen young men, studious of the "New Philosophy," who met in one another's lodgings in Oxford or in London, in the middle of the seventeenth century, grew in numerical and in real strength, until, in its latter part, the "Royal Society for the Improvement of Natural Knowledge" had already become famous, and had acquired a claim upon the veneration of Englishmen, which it has ever since retained, as the principal focus of scientific activity in our islands, and the chief champion of the cause it was formed to support. It was by the aid of the Royal Society that Newton published his "Principia." If all the books in the world, except the Philosophical Transactions, were destroyed, it is safe to say that the foundations of physical science would remain unshaken, and that the vast intellectual progress of the last two centuries would be largely, though incompletely, recorded. Nor have any signs of halting or of decrepitude manifested themselves in our own times. As in Dr. Wallis's days, so in these, "our business is, precluding theology and state affairs, to discourse and consider of philosophical enquiries." But our "Mathematick" is one which Newton would have to go to school to learn; our "Staticks, Mechanicks, Magneticks, Chymicks, and Natural Experiments" constitute a mass of physical and chemical knowledge, a glimpse at which would compensate Galileo for the doings of a score of inquisitorial cardinals; our "Physick" and "Anatomy" have embraced such infinite varieties of being, have laid open such new worlds in time and space, have grappled, not unsuccessfully, with such complex problems, that the eyes of Vesalius and of Harvey might be dazzled by the sight of the tree that has grown out of their grain of mustard seed. The fact is perhaps rather too much, than too little, forced upon one's notice, nowadays, that all this marvellous intellectual growth has a no less wonderful expression in practical life; and that, in this respect, if in no other, the movement symbolized by the progress of the Royal Society stands without a parallel in the history of mankind. A series of volumes as bulky as the Transactions of the Royal Society might possibly be filled with the subtle speculations of the schoolmen; not improbably, the obtaining a mastery over the products of mediæval thought might necessitate an even greater expenditure of time and of energy than the acquirement of the "New Philosophy;" but though such work engrossed the best intellects of Europe for a longer time than has elapsed since the great fire, its effects were "writ in water," so far as our social state is concerned. On the other hand, if the noble first President of the Royal Society could revisit the upper air and once more gladden his eyes with a sight of the familiar mace, he would find himself in the midst of a material civilization more different from that of his day, than that of the seventeenth, was from that of the first, century. And if Lord Brouncker's native sagacity had not deserted his ghost, he would need no long reflection to discover that all these great ships, these railways, these telegraphs, these factories, these printing presses, without which the whole fabric of modern English society would collapse into a mass of stagnant and starving pauperism,--that all these pillars of our State are but the ripples and the bubbles upon the surface of that great spiritual stream, the springs of which, only, he and his fellows were privileged to see; and seeing, to recognise as that which it behoved them above all things to keep pure and undefiled. It may not be too great a flight of imagination to conceive our noble _revenant_ not forgetful of the great troubles of his own day, and anxious to know how often London had been burned down since his time, and how often the plague had carried off its thousands. He would have to learn that, although London contains tenfold the inflammable matter that it did in 1666; though, not content with filling our rooms with woodwork and light draperies, we must needs lead inflammable and explosive gases into every corner of our streets and houses, we never allow even a street to burn down. And if he asked how this had come about, we should have to explain that the improvement of natural knowledge has furnished us with dozens of machines for throwing water upon fires, anyone of which would have furnished the ingenious Mr. Hooke, the first "curator and experimenter" of the Royal Society, with ample materials for discourse before half a dozen meetings of that body; and that, to say truth, except for the progress of natural knowledge, we should not have been able to make even the tools by which these machines are constructed. And, further, it would be necessary to add, that although severe fires sometimes occur and inflict great damage, the loss is very generally compensated by societies, the operations of which have been rendered possible only by the progress of natural knowledge in the direction of mathematics, and the accumulation of wealth in virtue of other natural knowledge. But the plague? My Lord Brouncker's observation would not, I fear, lead him to think that Englishmen of the nineteenth century are purer in life, or more fervent in religious faith, than the generation which could produce a Boyle, an Evelyn, and a Milton. He might find the mud of society at the bottom, instead of at the top, but I fear that the sum total would be as deserving of swift judgment as at the time of the Restoration. And it would be our duty to explain once more, and this time not without shame, that we have no reason to believe that it is the improvement of our faith, nor that of our morals, which keeps the plague from our city; but, again, that it is the improvement of our natural knowledge. We have learned that pestilences will only take up their abode among those who have prepared unswept and ungarnished residences for them. Their cities must have narrow, unwatered streets, foul with accumulated garbage. Their houses must be ill-drained, ill-lighted, ill-ventilated. Their subjects must be ill-washed, ill-fed, ill-clothed. The London of 1665 was such a city. The cities of the East, where plague has an enduring dwelling, are such cities. We, in later times, have learned somewhat of Nature, and partly obey her. Because of this partial improvement of our natural knowledge and of that fractional obedience, we have no plague; because that knowledge is still very imperfect and that obedience yet incomplete, typhus is our companion and cholera our visitor. But it is not presumptuous to express the belief that, when our knowledge is more complete and our obedience the expression of our knowledge, London will count her centuries of freedom from typhus and cholera, as she now gratefully reckons her two hundred years of ignorance of that plague which swooped upon her thrice in the first half of the seventeenth century. Surely, there is nothing in these explanations which is not fully borne out by the facts? Surely, the principles involved in them are now admitted among the fixed beliefs of all thinking men? Surely, it is true that our countrymen are less subject to fire, famine, pestilence, and all the evils which result from a want of command over and due anticipation of the course of Nature, than were the countrymen of Milton; and health, wealth, and well-being are more abundant with us than with them? But no less certainly is the difference due to the improvement of our knowledge of Nature, and the extent to which that improved knowledge has been incorporated with the household words of men, and has supplied the springs of their daily actions. Granting for a moment, then, the truth of that which the depreciators of natural knowledge are so fond of urging, that its improvement can only add to the resources of our material civilization; admitting it to be possible that the founders of the Royal Society themselves looked for no other reward than this, I cannot confess that I was guilty of exaggeration when I hinted, that to him who had the gift of distinguishing between prominent events and important events, the origin of a combined effort on the part of mankind to improve natural knowledge might have loomed larger than the Plague and have outshone the glare of the Fire; as a something fraught with a wealth of beneficence to mankind, in comparison with which the damage done by those ghastly evils would shrink into insignificance. It is very certain that for every victim slain by the plague, hundreds of mankind exist and find a fair share of happiness in the world, by the aid of the spinning jenny. And the great fire, at its worst, could not have burned the supply of coal, the daily working of which, in the bowels of the earth, made possible by the steam pump, gives rise to an amount of wealth to which the millions lost in old London are but as an old song. But spinning jenny and steam pump are, after all, but toys, possessing an accidental value; and natural knowledge creates multitudes of more subtle contrivances, the praises of which do not happen to be sung because they are not directly convertible into instruments for creating wealth. When I contemplate natural knowledge squandering such gifts among men, the only appropriate comparison I can find for her is, to liken her to such a peasant woman as one sees in the Alps, striding ever upward, heavily burdened, and with mind bent only on her home; but yet, without effort and without thought, knitting for her children. Now stockings are good and comfortable things, and the children will undoubtedly be much the better for them; but surely it would be short-sighted, to say the least of it, to depreciate this toiling mother as a mere stocking-machine--a mere provider of physical comforts? However, there are blind leaders of the blind, and not a few of them, who take this view of natural knowledge, and can see nothing in the bountiful mother of humanity but a sort of comfort-grinding machine. According to them, the improvement of natural knowledge always has been, and always must be, synonymous with no more than the improvement of the material resources and the increase of the gratifications of men. Natural knowledge is, in their eyes, no real mother of mankind, bringing them up with kindness, and, if need be, with sternness, in the way they should go, and instructing them in all things needful for their welfare; but a sort of fairy godmother, ready to furnish her pets with shoes of swiftness, swords of sharpness, and omnipotent Aladdin's lamps, so that they may have telegraphs to Saturn, and see the other side of the moon, and thank God they are better than their benighted ancestors. If this talk were true, I, for one, should not greatly care to toil in the service of natural knowledge. I think I would just as soon be quietly chipping my own flint axe, after the manner of my forefathers a few thousand years back, as be troubled with the endless malady of thought which now infests us all, for such reward. But I venture to say that such views are contrary alike to reason and to fact. Those who discourse in such fashion seem to me to be so intent upon trying to see what is above Nature, or what is behind her, that they are blind to what stares them in the face, in her. I should not venture to speak thus strongly if my justification were not to be found in the simplest and most obvious facts,--if it needed more than an appeal to the most notorious truths to justify my assertion, that the improvement of natural knowledge, whatever direction it has taken, and however low the aims of those who may have commenced it--has not only conferred practical benefits on men, but, in so doing, has effected a revolution in their conceptions of the universe and of themselves, and has profoundly altered their modes of thinking and their views of right and wrong. I say that natural knowledge, seeking to satisfy natural wants, has found the ideas which can alone still spiritual cravings. I say that natural knowledge, in desiring to ascertain the laws of comfort, has been driven to discover those of conduct; and to lay the foundations of a new morality. Let us take these points separately; and, first, what great ideas has natural knowledge introduced into men's minds? I cannot but think that the foundations of all natural knowledge were laid when the reason of man first came face to face with the facts of Nature: when the savage first learned that the fingers of one hand are fewer than those of both; that it is shorter to cross a stream than to head it; that a stone stops where it is unless it be moved, and that it drops from the hand which lets it go; that light and heat come and go with the sun; that sticks burn away in a fire; that plants and animals grow and die; that if he struck his fellow-savage a blow he would make him angry, and perhaps get a blow in return, while if he offered him a fruit he would please him, and perhaps receive a fish in exchange. When men had acquired this much knowledge, the outlines, rude though they were, of mathematics, of physics, of chemistry, of biology, of moral, economical, and political science, were sketched. Nor did the germ of religion fail when science began to bud. Listen to words which, though new, are yet three thousand years old:-- "...When in heaven the stars about the moon Look beautiful, when all the winds are laid, And every height comes out, and jutting peak And valley, and the immeasurable heavens Break open to their highest, and all the stars Shine, and the shepherd gladdens in his heart."[1] If the half-savage Greek could share our feelings thus far, it is irrational to doubt that he went further, to find, as we do, that upon that brief gladness there follows a certain sorrow,--the little light of awakened human intelligence shines so mere a spark amidst the abyss of the unknown and unknowable; seems so insufficient to do more than illuminate the imperfections that cannot be remedied, the aspirations that cannot be realized, of man's own nature. But in this sadness, this consciousness of the limitation of man, this sense of an open secret which he cannot penetrate, lies the essence of all religion; and the attempt to embody it in the forms furnished by the intellect is the origin of the higher theologies. Thus it seems impossible to imagine but that the foundations of all knowledge--secular or sacred--were laid when intelligence dawned, though the superstructure remained for long ages so slight and feeble as to be compatible with the existence of almost any general view respecting the mode of governance of the universe. No doubt, from the first, there were certain phenomena which, to the rudest mind, presented a constancy of occurrence, and suggested that a fixed order ruled, at any rate, among them. I doubt if the grossest of Fetish worshippers ever imagined that a stone must have a god within it to make it fall, or that a fruit had a god within it to make it taste sweet. With regard to such matters as these, it is hardly questionable that mankind from the first took strictly positive and scientific views. But, with respect to all the less familiar occurrences which present themselves, uncultured man, no doubt, has always taken himself as the standard of comparison, as the centre and measure of the world; nor could he well avoid doing so. And finding that his apparently uncaused will has a powerful effect in giving rise to many occurrences, he naturally enough ascribed other and greater events to other and greater volitions, and came to look upon the world and all that therein is, as the product of the volitions of persons like himself, but stronger, and capable of being appeased or angered, as he himself might be soothed or irritated. Through such conceptions of the plan and working of the universe all mankind have passed, or are passing. And we may now consider, what has been the effect of the improvement of natural knowledge on the views of men who have reached this stage, and who have begun to cultivate natural knowledge with no desire but that of "increasing God's honour and bettering man's estate." For example: what could seem wiser, from a mere material point of view, more innocent, from a theological one, to an ancient people, than that they should learn the exact succession of the seasons, as warnings for their husbandmen; or the position of the stars, as guides to their rude navigators? But what has grown out of this search for natural knowledge of so merely useful a character? You all know the reply. Astronomy,--which of all sciences has filled men's minds with general ideas of a character most foreign to their daily experience, and has, more than any other, rendered it impossible for them to accept the beliefs of their fathers. Astronomy,--which tells them that this so vast and seemingly solid earth is but an atom among atoms, whirling, no man knows whither, through illimitable space; which demonstrates that what we call the peaceful heaven above us, is but that space, filled by an infinitely subtle matter whose particles are seething and surging, like the waves of an angry sea; which opens up to us infinite regions where nothing is known, or ever seems to have been known, but matter and force, operating according to rigid rules; which leads us to contemplate phenomena the very nature of which demonstrates that they must have had a beginning, and that they must have an end, but the very nature of which also proves that the beginning was, to our conceptions of time, infinitely remote, and that the end is as immeasurably distant. But it is not alone those who pursue astronomy who ask for bread and receive ideas. What more harmless than the attempt to lift and distribute water by pumping it; what more absolutely and grossly utilitarian? But out of pumps grew the discussions about Nature's abhorrence of a vacuum; and then it was discovered that Nature does not abhor a vacuum, but that air has weight; and that notion paved the way for the doctrine that all matter has weight, and that the force which produces weight is co-extensive with the universe,--in short, to the theory of universal gravitation and endless force. While learning how to handle gases led to the discovery of oxygen, and to modern chemistry, and to the notion of the indestructibility of matter. Again, what simpler, or more absolutely practical, than the attempt to keep the axle of a wheel from heating when the wheel turns round very fast? How useful for carters and gig drivers to know something about this; and how good were it, if any ingenious person would find out the cause of such phenomena, and thence educe a general remedy for them. Such an ingenious person was Count Rumford; and he and his successors have landed us in the theory of the persistence, or indestructibility, of force. And in the infinitely minute, as in the infinitely great, the seekers after natural knowledge, of the kinds called physical and chemical, have everywhere found a definite order and succession of events which seem never to be infringed. And how has it fared with "Physick" and Anatomy? Have the anatomist, the physiologist, or the physician, whose business it has been to devote themselves assiduously to that eminently practical and direct end, the alleviation of the sufferings of mankind,--have they been able to confine their vision more absolutely to the strictly useful? I fear they are worst offenders of all. For if the astronomer has set before us the infinite magnitude of space, and the practical eternity of the duration of the universe; if the physical and chemical philosophers have demonstrated the infinite minuteness of its constituent parts, and the practical eternity of matter and of force; and if both have alike proclaimed the universality of a definite and predicable order and succession of events, the workers in biology have not only accepted all these, but have added more startling theses of their own. For, as the astronomers discover in the earth no centre of the universe, but an eccentric speck, so the naturalists find man to be no centre of the living world, but one amidst endless modifications of life; and as the astronomer observes the mark of practically endless time set upon the arrangements of the solar system, so the student of life finds the records of ancient forms of existence peopling the world for ages, which, in relation to human experience, are infinite. Furthermore, the physiologist finds life to be as dependent for its manifestation on particular molecular arrangements as any physical or chemical phenomenon; and, wherever he extends his researches, fixed order and unchanging causation reveal themselves, as plainly as in the rest of Nature. Nor can I find that any other fate has awaited the germ of Religion. Arising, like all other kinds of knowledge, out of the action and interaction of man's mind, with that which is not man's mind, it has taken the intellectual coverings of Fetishism or Polytheism; of Theism or Atheism; of Superstition or Rationalism. With these, and their relative merits and demerits, I have nothing to do; but this it is needful for my purpose to say, that if the religion of the present differs from that of the past, it is because the theology of the present has become more scientific than that of the past; because it has not only renounced idols of wood and idols of stone, but begins to see the necessity of breaking in pieces the idols built up of books and traditions and fine-spun ecclesiastical cobwebs: and of cherishing the noblest and most human of man's emotions, by worship "for the most part of the silent sort" at the altar of the Unknown and Unknowable. Such are a few of the new conceptions implanted in our minds by the improvement of natural knowledge. Men have acquired the ideas of the practically infinite extent of the universe and of its practical eternity; they are familiar with the conception that our earth is but an infinitesimal fragment of that part of the universe which can be seen; and that, nevertheless, its duration is, as compared with our standards of time, infinite. They have further acquired the idea that man is but one of innumerable forms of life now existing in the globe, and that the present existences are but the last of an immeasurable series of predecessors. Moreover, every step they have made in natural knowledge has tended to extend and rivet in their minds the conception of a definite order of the universe--which is embodied in what are called, by an unhappy metaphor, the laws of Nature--and to narrow the range and loosen the force of men's belief in spontaneity, or in changes other than such as arise out of that definite order itself. Whether these ideas are well or ill founded is not the question. No one can deny that they exist, and have been the inevitable outgrowth of the improvement of natural knowledge. And if so, it cannot be doubted that they are changing the form of men's most cherished and most important convictions. And as regards the second point--the extent to which the improvement of natural knowledge has remodelled and altered what may be termed the intellectual ethics of men,--what are among the moral convictions most fondly held by barbarous and semi-barbarous people? They are the convictions that authority is the soundest basis of belief; that merit attaches to a readiness to believe; that the doubting disposition is a bad one, and scepticism a sin; that when good authority has pronounced what is to be believed, and faith has accepted it, reason has no further duty. There are many excellent persons who yet hold by these principles, and it is not my present business, or intention, to discuss their views. All I wish to bring clearly before your minds is the unquestionable fact, that the improvement of natural knowledge is effected by methods which directly give the lie to all these convictions, and assume the exact reverse of each to be true. The improver of natural knowledge absolutely refuses to acknowledge authority, as such. For him, scepticism is the highest of duties; blind faith the one unpardonable sin. And it cannot be otherwise, for every great advance in natural knowledge has involved the absolute rejection of authority, the cherishing of the keenest scepticism, the annihilation of the spirit of blind faith: and the most ardent votary of science holds his firmest convictions, not because the men he most venerates hold them; not because their verity is testified by portents and wonders; but because his experience teaches him that whenever he chooses to bring these convictions into contact with their primary source, Nature--whenever he thinks fit to test them by appealing to experiment and to observation--Nature will confirm them. The man of science has learned to believe in justification, not by faith, but by verification. Thus, without for a moment pretending to despise the practical results of the improvement of natural knowledge, and its beneficial influence on material civilization, it must, I think, be admitted that the great ideas, some of which I have indicated, and the ethical spirit which I have endeavoured to sketch, in the few moments which remained at my disposal, constitute the real and permanent significance of natural knowledge. If these ideas be destined, as I believe they are, to be more and more firmly established as the world grows older; if that spirit be fated, as I believe it is, to extend itself into all departments of human thought, and to become co-extensive with the range of knowledge; if, as our race approaches its maturity, it discovers, as I believe it will, that there is but one kind of knowledge and but one method of acquiring it; then we, who are still children, may justly feel it our highest duty to recognise the advisableness of improving natural knowledge, and so to aid ourselves and our successors in their course towards the noble goal which lies before mankind. FOOTNOTE: [1] Need it be said that this is Tennyson's English for Homer's Greek? II. EMANCIPATION--BLACK AND WHITE. Quashie's plaintive inquiry, "Am I not a man and a brother?" seems at last to have received its final reply--the recent decision of the fierce trial by battle on the other side of the Atlantic fully concurring with that long since delivered here in a more peaceful way. The question is settled; but even those who are most thoroughly convinced that the doom is just, must see good grounds for repudiating half the arguments which have been employed by the winning side; and for doubting whether its ultimate results will embody the hopes of the victors, though they may more than realize the fears of the vanquished. It may be quite true that some negroes are better than some white men; but no rational man, cognizant of the facts, believes that the average negro is the equal, still less the superior, of the average white man. And, if this be true, it is simply incredible that, when all his disabilities are removed, and our prognathous relative has a fair field and no favour, as well as no oppressor, he will be able to compete successfully with his bigger-brained and smaller-jawed rival, in a contest which is to be carried on by thoughts and not by bites. The highest places in the hierarchy of civilization will assuredly not be within the reach of our dusky cousins, though it is by no means necessary that they should be restricted to the lowest. But whatever the position of stable equilibrium into which the laws of social gravitation may bring the negro, all responsibility for the result will henceforward lie between Nature and him. The white man may wash his hands of it, and the Caucasian conscience be void of reproach for evermore. And this, if we look to the bottom of the matter, is the real justification for the abolition policy. The doctrine of equal natural rights may be an illogical delusion; emancipation may convert the slave from a well fed animal into a pauperised man; mankind may even have to do without cotton shirts; but all these evils must be faced, if the moral law, that no human being can arbitrarily dominate over another without grievous damage to his own nature, be, as many think, as readily demonstrable by experiment as any physical truth. If this be true, no slavery can be abolished without a double emancipation, and the master will benefit by freedom more than the freed-man. The like considerations apply to all the other questions of emancipation which are at present stirring the world--the multifarious demands that classes of mankind shall be relieved from restrictions imposed by the artifice of man, and not by the necessities of Nature. One of the most important, if not the most important, of all these, is that which daily threatens to become the "irrepressible" woman question. What social and political rights have women? What ought they to be allowed, or not allowed, to do, be, and suffer? And, as involved in, and underlying all these questions, how ought they to be educated? There are philogynists as fanatical as any "misogynists" who, reversing our antiquated notions, bid the man look upon the woman as the higher type of humanity; who ask us to regard the female intellect as the clearer and the quicker, if not the stronger; who desire us to look up to the feminine moral sense as the purer and the nobler; and bid man abdicate his usurped sovereignty over Nature in favour of the female line. On the other hand, there are persons not to be outdone in all loyalty and just respect for woman-kind, but by nature hard of head and haters of delusion, however charming, who not only repudiate the new woman-worship which so many sentimentalists and some philosophers are desirous of setting up, but, carrying their audacity further, deny even the natural equality of the sexes. They assert, on the contrary, that in every excellent character, whether mental or physical, the average woman is inferior to the average man, in the sense of having that character less in quantity, and lower in quality. Tell these persons of the rapid perceptions and the instinctive intellectual insight of women, and they reply that the feminine mental peculiarities, which pass under these names, are merely the outcome of a greater impressibility to the superficial aspects of things, and of the absence of that restraint upon expression, which, in men, is imposed by reflection and a sense of responsibility. Talk of the passive endurance of the weaker sex, and opponents of this kind remind you that Job was a man, and that, until quite recent times, patience and long-suffering were not counted among the specially feminine virtues. Claim passionate tenderness as especially feminine, and the inquiry is made whether all the best love-poetry in existence (except, perhaps, the "Sonnets from the Portuguese") has not been written by men; whether the song which embodies the ideal of pure and tender passion--Adelaida--was written by _Frau_ Beethoven; whether it was the Fornarina, or Raphael, who painted the Sistine Madonna. Nay, we have known one such heretic go so far as to lay his hands upon the ark itself, so to speak, and to defend the startling paradox that, even in physical beauty, man is the superior. He admitted, indeed, that there was a brief period of early youth when it might be hard to say whether the prize should be awarded to the graceful undulations of the female figure, or the perfect balance and supple vigour of the male frame. But while our new Paris might hesitate between the youthful Bacchus and the Venus emerging from the foam, he averred that, when Venus and Bacchus had reached thirty, the point no longer admitted of a doubt; the male form having then attained its greatest nobility, while the female is far gone in decadence; and that, at this epoch, womanly beauty, so far as it is independent of grace or expression, is a question of drapery and accessories. Supposing, however, that all these arguments have a certain foundation; admitting for a moment, that they are comparable to those by which the inferiority of the negro to the white man may be demonstrated, are they of any value as against woman-emancipation? Do they afford us the smallest ground for refusing to educate women as well as men--to give women the same civil and political rights as men? No mistake is so commonly made by clever people as that of assuming a cause to be bad because the arguments of its supporters are, to a great extent, nonsensical. And we conceive that those who may laugh at the arguments of the extreme philogynists, may yet feel bound to work heart and soul towards the attainment of their practical ends. As regards education, for example. Granting the alleged defects of women, is it not somewhat absurd to sanction and maintain a system of education which would seem to have been specially contrived to exaggerate all these defects? Naturally not so firmly strung, nor so well balanced, as boys, girls are in great measure debarred from the sports and physical exercises which are justly thought absolutely necessary for the full development of the vigour of the more favoured sex. Women are, by nature, more excitable than men--prone to be swept by tides of emotion, proceeding from hidden and inward, as well as from obvious and external causes; and female education does its best to weaken every physical counterpoise to this nervous mobility--tends in all ways to stimulate the emotional part of the mind and stunt the rest. We find girls naturally timid, inclined to dependence, born conservatives; and we teach them that independence is unladylike; that blind faith is the right frame of mind; and that whatever we may be permitted, and indeed encouraged, to do to our brother, our sister is to be left to the tyranny of authority and tradition. With few insignificant exceptions, girls have been educated either to be drudges, or toys, beneath man; or a sort of angels above him; the highest ideal aimed at oscillating between Clärchen and Beatrice. The possibility that the ideal of womanhood lies neither in the fair saint, nor in the fair sinner; that the female type of character is neither better nor worse than the male, but only weaker; that women are meant neither to be men's guides nor their playthings, but their comrades, their fellows and their equals, so far as Nature puts no bar to that equality, does not seem to have entered into the minds of those who have had the conduct of the education of girls. If the present system of female education stands self-condemned, as inherently absurd; and if that which we have just indicated is the true position of woman, what is the first step towards a better state of things? We reply, emancipate girls. Recognise the fact that they share the senses, perceptions, feelings, reasoning powers, emotions, of boys, and that the mind of the average girl is less different from that of the average boy, than the mind of one boy is from that of another; so that whatever argument justifies a given education for all boys, justifies its application to girls as well. So far from imposing artificial restrictions upon the acquirement of knowledge by women, throw every facility in their way. Let our Faustinas, if they will, toil through the whole round of "Juristerei und Medizin, Und leider! auch Philosophie." Let us have "sweet girl graduates" by all means. They will be none the less sweet for a little wisdom; and the "golden hair" will not curl less gracefully outside the head by reason of there being brains within. Nay, if obvious practical difficulties can be overcome, let those women who feel inclined to do so descend into the gladiatorial arena of life, not merely in the guise of _retiariæ_, as heretofore, but as bold _sicariæ_, breasting the open fray. Let them, if they so please, become merchants, barristers, politicians. Let them have a fair field, but let them understand, as the necessary correlative, that they are to have no favour. Let Nature alone sit above the lists, "rain influence and judge the prize." And the result? For our parts, though loth to prophesy, we believe it will be that of other emancipations. Women will find their place, and it will neither be that in which they have been held, nor that to which some of them aspire. Nature's old salique law will not be repealed, and no change of dynasty will be effected. The big chests, the massive brains, the vigorous muscles and stout frames, of the best men will carry the day, whenever it is worth their while to contest the prizes of life with the best women. And the hardship of it is, that the very improvement of the women will lessen their chances. Better mothers will bring forth better sons, and the impetus gained by the one sex will be transmitted, in the next generation, to the other. The most Darwinian of theorists will not venture to propound the doctrine, that the physical disabilities under which women have hitherto laboured, in the struggle for existence with men, are likely to be removed by even the most skilfully conducted process of educational selection. We are, indeed, fully prepared to believe that the bearing of children may, and ought, to become as free from danger and long disability, to the civilized woman, as it is to the savage; nor is it improbable that, as society advances towards its right organization, motherhood will occupy a less space of woman's life than it has hitherto done. But still, unless the human species is to come to an end altogether--a consummation which can hardly be desired by even the most ardent advocate of "women's rights"--somebody must be good enough to take the trouble and responsibility of annually adding to the world exactly as many people as die out of it. In consequence of some domestic difficulties, Sydney Smith is said to have suggested that it would have been good for the human race had the model offered by the hive been followed, and had all the working part of the female community been neuters. Failing any thorough-going reform of this kind, we see nothing for it but the old division of humanity into men potentially, or actually, fathers, and women potentially, if not actually, mothers. And we fear that so long as this potential motherhood is her lot, woman will be found to be fearfully weighted in the race of life. The duty of man is to see that not a grain is piled upon that load beyond what Nature imposes; that injustice is not added to inequality. III. A LIBERAL EDUCATION: AND WHERE TO FIND IT. The business which the South London Working Men's College has undertaken is a great work; indeed, I might say, that Education, with which that college proposes to grapple, is the greatest work of all those which lie ready to a man's hand just at present. And, at length, this fact is becoming generally recognised. You cannot go anywhere without hearing a buzz of more or less confused and contradictory talk on this subject--nor can you fail to notice that, in one point at any rate, there is a very decided advance upon like discussions in former days. Nobody outside the agricultural interest now dares to say that education is a bad thing. If any representative of the once large and powerful party, which, in former days, proclaimed this opinion, still exists in a semi-fossil state, he keeps his thoughts to himself. In fact, there is a chorus of voices, almost distressing in their harmony, raised in favour of the doctrine that education is the great panacea for human troubles, and that, if the country is not shortly to go to the dogs, everybody must be educated. The politicians tell us, "you must educate the masses because they are going to be masters." The clergy join in the cry for education, for they affirm that the people are drifting away from church and chapel into the broadest infidelity. The manufacturers and the capitalists swell the chorus lustily. They declare that ignorance makes bad workmen; that England will soon be unable to turn out cotton goods, or steam engines, cheaper than other people; and then, Ichabod! Ichabod! the glory will be departed from us. And a few voices are lifted up in favour of the doctrine that the masses should be educated because they are men and women with unlimited capacities of being, doing, and suffering, and that it is as true now, as ever it was, that the people perish for lack of knowledge. These members of the minority, with whom I confess I have a good deal of sympathy, are doubtful whether any of the other reasons urged in favour of the education of the people are of much value--whether, indeed, some of them are based upon either wise or noble grounds of action. They question if it be wise to tell people that you will do for them, out of fear of their power, what you have left undone, so long as your only motive was compassion for their weakness and their sorrows. And, if ignorance of everything which it is needful a ruler should know is likely to do so much harm in the governing classes of the future, why is it, they ask reasonably enough, that such ignorance in the governing classes of the past has not been viewed with equal horror? Compare the average artisan and the average country squire, and it may be doubted if you will find a pin to choose between the two in point of ignorance, class feeling, or prejudice. It is true that the ignorance is of a different sort--that the class feeling is in favour of a different class, and that the prejudice has a distinct flavour of wrong-headedness in each case--but it is questionable if the one is either a bit better, or a bit worse than the other. The old protectionist theory is the doctrine of trades unions as applied by the squires, and the modern trades unionism is the doctrine of the squires applied by the artisans. Why should we be worse off under one _régime_ than under the other? Again, this sceptical minority asks the clergy to think whether it is really want of education which keeps the masses away from their ministrations--whether the most completely educated men are not as open to reproach on this score as the workmen; and whether, perchance, this may not indicate that it is not education which lies at the bottom of the matter? Once more, these people, whom there is no pleasing, venture to doubt whether the glory, which rests upon being able to undersell all the rest of the world, is a very safe kind of glory--whether we may not purchase it too dear; especially if we allow education, which ought to be directed to the making of men, to be diverted into a process of manufacturing human tools, wonderfully adroit in the exercise of some technical industry, but good for nothing else. And, finally, these people inquire whether it is the masses alone who need a reformed and improved education. They ask whether the richest of our public schools might not well be made to supply knowledge, as well as gentlemanly habits, a strong class feeling, and eminent proficiency in cricket. They seem to think that the noble foundations of our old universities are hardly fulfilling their functions in their present posture of half-clerical seminaries, half racecourses, where men are trained to win a senior wranglership, or a double-first, as horses are trained to win a cup, with as little reference to the needs of after-life in the case of the man as in that of the racer. And, while as zealous for education as the rest, they affirm that, if the education of the richer classes were such as to fit them to be the leaders and the governors of the poorer; and, if the education of the poorer classes were such as to enable them to appreciate really wise guidance and good governance; the politicians need not fear mob-law, nor the clergy lament their want of flocks, nor the capitalists prognosticate the annihilation of the prosperity of the country. Such is the diversity of opinion upon the why and the wherefore of education. And my hearers will be prepared to expect that the practical recommendations which are put forward are not less discordant. There is a loud cry for compulsory education. We English, in spite of constant experience to the contrary, preserve a touching faith in the efficacy of acts of parliament; and I believe we should have compulsory education in the course of next session, if there were the least probability that half a dozen leading statesmen of different parties would agree what that education should be. Some hold that education without theology is worse than none. Others maintain, quite as strongly, that education with theology is in the same predicament. But this is certain, that those who hold the first opinion can by no means agree what theology should be taught; and that those who maintain the second are in a small minority. At any rate "make people learn to read, write, and cipher," say a great many; and the advice is undoubtedly sensible as far as it goes. But, as has happened to me in former days, those who, in despair of getting anything better, advocate this measure, are met with the objection that it is very like making a child practise the use of a knife, fork, and spoon, without giving it a particle of meat. I really don't know what reply is to be made to such an objection. But it would be unprofitable to spend more time in disentangling, or rather in showing up the knots in, the ravelled skeins of our neighbours. Much more to the purpose is it to ask if we possess any clue of our own which may guide us among these entanglements. And by way of a beginning, let us ask ourselves--What is education? Above all things, what is our ideal of a thoroughly liberal education?--of that education which, if we could begin life again, we would give ourselves--of that education which, if we could mould the fates to our own will, we would give our children. Well, I know not what may be your conceptions upon this matter, but I will tell you mine, and I hope I shall find that our views are not very discrepant. Suppose it were perfectly certain that the life and fortune of every one of us would, one day or other, depend upon his winning or losing a game at chess. Don't you think that we should all consider it to be a primary duty to learn at least the names and the moves of the pieces; to have a notion of a gambit, and a keen eye for all the means of giving and getting out of check? Do you not think that we should look with a disapprobation amounting to scorn, upon the father who allowed his son, or the state which allowed its members, to grow up without knowing a pawn from a knight? Yet it is a very plain and elementary truth, that the life, the fortune, and the happiness of every one of us, and, more or less, of those who are connected with us, do depend upon our knowing something of the rules of a game infinitely more difficult and complicated than chess. It is a game which has been played for untold ages, every man and woman of us being one of the two players in a game of his or her own. The chess-board is the world, the pieces are the phenomena of the universe, the rules of the game are what we call the laws of Nature. The player on the other side is hidden from us. We know that his play is always fair, just, and patient. But also we know, to our cost, that he never overlooks a mistake, or makes the smallest allowance for ignorance. To the man who plays well, the highest stakes are paid, with that sort of overflowing generosity with which the strong shows delight in strength. And one who plays ill is checkmated--without haste, but without remorse. My metaphor will remind some of you of the famous picture in which Retzsch has depicted Satan playing at chess with man for his soul. Substitute for the mocking fiend in that picture, a calm, strong angel who is playing for love, as we say, and would rather lose than win--and I should accept it as an image of human life. Well, what I mean by Education is learning the rules of this mighty game. In other words, education is the instruction of the intellect in the laws of Nature, under which name I include not merely things and their forces, but men and their ways; and the fashioning of the affections and of the will into an earnest and loving desire to move in harmony with those laws. For me, education means neither more nor less than this. Anything which professes to call itself education must be tried by this standard, and if it fails to stand the test, I will not call it education, whatever may be the force of authority, or of numbers, upon the other side. It is important to remember that, in strictness, there is no such thing as an uneducated man. Take an extreme case. Suppose that an adult man, in the full vigour of his faculties, could be suddenly placed in the world, as Adam is said to have been, and then left to do as he best might. How long would he be left uneducated? Not five minutes. Nature would begin to teach him, through the eye, the ear, the touch, the properties of objects. Pain and pleasure would be at his elbow telling him to do this and avoid that; and by slow degrees the man would receive an education, which, if narrow, would be thorough, real, and adequate to his circumstances, though there would be no extras and very few accomplishments. And if to this solitary man entered a second Adam, or, better still, an Eve, a new and greater world, that of social and moral phenomena, would be revealed. Joys and woes, compared with which all others might seem but faint shadows, would spring from the new relations. Happiness and sorrow would take the place of the coarser monitors, pleasure and pain; but conduct would still be shaped by the observation of the natural consequences of actions; or, in other words, by the laws of the nature of man. To every one of us the world was once as fresh and new as to Adam. And then, long before we were susceptible of any other mode of instruction, Nature took us in hand, and every minute of waking life brought its educational influence, shaping our actions into rough accordance with Nature's laws, so that we might not be ended untimely by too gross disobedience. Nor should I speak of this process of education as past, for any one, be he as old as he may. For every man, the world is as fresh as it was at the first day, and as full of untold novelties for him who has the eyes to see them. And Nature is still continuing her patient education of us in that great university, the universe, of which we are all members--Nature having no Test-Acts. Those who take honours in Nature's university, who learn the laws which govern men and things and obey them, are the really great and successful men in this world. The great mass of mankind are the "Poll," who pick up just enough to get through without much discredit. Those who won't learn at all are plucked; and then you can't come up again. Nature's pluck means extermination. Thus the question of compulsory education is settled so far as Nature is concerned. Her bill on that question was framed and passed long ago. But, like all compulsory legislation, that of Nature is harsh and wasteful in its operation. Ignorance is visited as sharply as wilful disobedience--incapacity meets with the same punishment as crime. Nature's discipline is not even a word and a blow, and the blow first; but the blow without the word. It is left to you to find out why your ears are boxed. The object of what we commonly call education--that education in which man intervenes and which I shall distinguish as artificial education--is to make good these defects in Nature's methods; to prepare the child to receive Nature's education, neither incapably nor ignorantly, nor with wilful disobedience; and to understand the preliminary symptoms of her displeasure, without waiting for the box on the ear. In short, all artificial education ought to be an anticipation of natural education. And a liberal education is an artificial education, which has not only prepared a man to escape the great evils of disobedience to natural laws, but has trained him to appreciate and to seize upon the rewards, which Nature scatters with as free a hand as her penalties. That man, I think, has had a liberal education, who has been so trained in youth that his body is the ready servant of his will, and does with ease and pleasure all the work that, as a mechanism, it is capable of; whose intellect is a clear, cold, logic engine, with all its parts of equal strength, and in smooth working order; ready, like a steam engine, to be turned to any kind of work, and spin the gossamers as well as forge the anchors of the mind; whose mind is stored with a knowledge of the great and fundamental truths of Nature and of the laws of her operations; one who, no stunted ascetic, is full of life and fire, but whose passions are trained to come to heel by a vigorous will, the servant of a tender conscience; who has learned to love all beauty, whether of Nature or of art, to hate all vileness, and to respect others as himself. Such an one and no other, I conceive, has had a liberal education; for he is, as completely as a man can be, in harmony with Nature. He will make the best of her, and she of him. They will get on together rarely; she as his ever beneficent mother; he as her mouth-piece, her conscious self, her minister and interpreter. Where is such an education as this to be had? Where is there any approximation to it? Has any one tried to found such an education? Looking over the length and breadth of these islands, I am afraid that all these questions must receive a negative answer. Consider our primary schools, and what is taught in them. A child learns:-- 1. To read, write, and cipher, more or less well; but in a very large proportion of cases not so well as to take pleasure in reading, or to be able to write the commonest letter properly. 2. A quantity of dogmatic theology, of which the child, nine times out of ten, understands next to nothing. 3. Mixed up with this, so as to seem to stand or fall with it, a few of the broadest and simplest principles of morality. This, to my mind, is much as if a man of science should make the story of the fall of the apple in Newton's garden, an integral part of the doctrine of gravitation, and teach it as of equal authority with the law of the inverse squares. 4. A good deal of Jewish history and Syrian geography, and, perhaps, a little something about English history and the geography of the child's own country. But I doubt if there is a primary school in England in which hangs a map of the hundred in which the village lies, so that the children may be practically taught by it what a map means. 5. A certain amount of regularity, attentive obedience, respect for others: obtained by fear, if the master be incompetent or foolish; by love and reverence, if he be wise. So far as this school course embraces a training in the theory and practice of obedience to the moral laws of Nature, I gladly admit, not only that it contains a valuable educational element, but that, so far, it deals with the most valuable and important part of all education. Yet, contrast what is done in this direction with what might be done; with the time given to matters of comparatively no importance; with the absence of any attention to things of the highest moment; and one is tempted to think of Falstaff's bill and "the halfpenny worth of bread to all that quantity of sack." Let us consider what a child thus "educated" knows, and what it does not know. Begin with the most important topic of all--morality, as the guide of conduct. The child knows well enough that some acts meet with approbation and some with disapprobation. But it has never heard that there lies in the nature of things a reason for every moral law, as cogent and as well defined as that which underlies every physical law; that stealing and lying are just as certain to be followed by evil consequences, as putting your hand in the fire, or jumping out of a garret window. Again, though the scholar may have been made acquainted, in dogmatic fashion, with the broad laws of morality, he has had no training in the application of those laws to the difficult problems which result from the complex conditions of modern civilization. Would it not be very hard to expect anyone to solve a problem in conic sections who had merely been taught the axioms and definitions of mathematical science? A workman has to bear hard labour, and perhaps privation, while he sees others rolling in wealth, and feeding their dogs with what would keep his children from starvation. Would it not be well to have helped that man to calm the natural promptings of discontent by showing him, in his youth, the necessary connexion of the moral law which prohibits stealing with the stability of society--by proving to him, once for all, that it is better for his own people, better for himself, better for future generations, that he should starve than steal? If you have no foundation of knowledge, or habit of thought, to work upon, what chance have you of persuading a hungry man that a capitalist is not a thief "with a circumbendibus?" And if he honestly believes that, of what avail is it to quote the commandment against stealing, when he proposes to make the capitalist disgorge? Again, the child learns absolutely nothing of the history or the political organization of his own country. His general impression is, that everything of much importance happened a very long while ago; and that the Queen and the gentlefolks govern the country much after the fashion of King David and the elders and nobles of Israel--his sole models. Will you give a man with this much information a vote? In easy times he sells it for a pot of beer. Why should he not? It is of about as much use to him as a chignon, and he knows as much what to do with it, for any other purpose. In bad times, on the contrary, he applies his simple theory of government, and believes that his rulers are the cause of his sufferings--a belief which sometimes bears remarkable practical fruits. Least of all, does the child gather from this primary "education" of ours a conception of the laws of the physical world, or of the relations of cause and effect therein. And this is the more to be lamented, as the poor are especially exposed to physical evils, and are more interested in removing them than any other class of the community. If any one is concerned in knowing the ordinary laws of mechanics one would think it is the hand-labourer, whose daily toil lies among levers and pulleys; or among the other implements of artisan work. And if any one is interested in the laws of health, it is the poor workman, whose strength is wasted by ill-prepared food, whose health is sapped by bad ventilation and bad drainage, and half whose children are massacred by disorders which might be prevented. Not only does our present primary education carefully abstain from hinting to the workman that some of his greatest evils are traceable to mere physical agencies, which could be removed by energy, patience, and frugality; but it does worse--it renders him, so far as it can, deaf to those who could help him, and tries to substitute an Oriental submission to what is falsely declared to be the will of God, for his natural tendency to strive after a better condition. What wonder then, if very recently, an appeal has been made to statistics for the profoundly foolish purpose of showing that education is of no good--that it diminishes neither misery, nor crime, among the masses of mankind? I reply, why should the thing which has been called education do either the one or the other? If I am a knave or a fool, teaching me to read and write won't make me less of either one or the other--unless somebody shows me how to put my reading and writing to wise and good purposes. Suppose any one were to argue that medicine is of no use, because it could be proved statistically, that the percentage of deaths was just the same, among people who had been taught how to open a medicine chest, and among those who did not so much as know the key by sight. The argument is absurd; but it is not more preposterous than that against which I am contending. The only medicine for suffering, crime, and all the other woes of mankind, is wisdom. Teach a man to read and write, and you have put into his hands the great keys of the wisdom box. But it is quite another matter whether he ever opens the box or not. And he is as likely to poison as to cure himself, if, without guidance, he swallows the first drug that comes to hand. In these times a man may as well be purblind, as unable to read--lame, as unable to write. But I protest that, if I thought the alternative were a necessary one, I would rather that the children of the poor should grow up ignorant of both these mighty arts, than that they should remain ignorant of that knowledge to which these arts are means. It may be said that all these animadversions may apply to primary schools, but that the higher schools, at any rate, must be allowed to give a liberal education. In fact, they professedly sacrifice everything else to this object. Let us inquire into this matter. What do the higher schools, those to which the great middle class of the country sends it children, teach, over and above the instruction given in the primary schools? There is a little more reading and writing of English. But, for all that, every one knows that it is a rare thing to find a boy of the middle or upper classes who can read aloud decently, or who can put his thoughts on paper in clear and grammatical (to say nothing of good or elegant) language. The "ciphering" of the lower schools expands into elementary mathematics in the higher; into arithmetic, with a little algebra, a little Euclid. But I doubt if one boy in five hundred has ever heard the explanation of a rule of arithmetic, or knows his Euclid otherwise than by rote. Of theology, the middle class schoolboy gets rather less than poorer children, less absolutely and less relatively, because there are so many other claims upon his attention. I venture to say that, in the great majority of cases, his ideas on this subject when he leaves school are of the most shadowy and vague description, and associated with painful impressions of the weary hours spent in learning collects and catechism by heart. Modern geography, modern history, modern literature; the English language as a language; the whole circle of the sciences, physical, moral, and social, are even more completely ignored in the higher than in the lower schools. Up till within a few years back, a boy might have passed through any one of the great public schools with the greatest distinction and credit, and might never so much as have heard of one of the subjects I have just mentioned. He might never have heard that the earth goes round the sun; that England underwent a great revolution in 1688, and France another in 1789; that there once lived certain notable men called Chaucer, Shakspeare, Milton, Voltaire, Goethe, Schiller. The first might be a German and the last an Englishman for anything he could tell you to the contrary. And as for science, the only idea the word would suggest to his mind would be dexterity in boxing. I have said that this was the state of things a few years back, for the sake of the few righteous who are to be found among the educational cities of the plain. But I would not have you too sanguine about the result, if you sound the minds of the existing generation of public school-boys, on such topics as those I have mentioned. Now let us pause to consider this wonderful state of affairs; for the time will come when Englishmen will quote it as the stock example of the stolid stupidity of their ancestors in the nineteenth century. The most thoroughly commercial people, the greatest voluntary wanderers and colonists the world has ever seen, are precisely the middle classes of this country. If there be a people which has been busy making history on the great scale for the last three hundred years--and the most profoundly interesting history--history which, if it happened to be that of Greece or Rome, we should study with avidity--it is the English. If there be a people which, during the same period, has developed a remarkable literature, it is our own. If there be a nation whose prosperity depends absolutely and wholly upon their mastery over the forces of Nature, upon their intelligent apprehension of, and obedience to, the laws of the creation and distribution of wealth, and of the stable equilibrium of the forces of society, it is precisely this nation. And yet this is what these wonderful people tell their sons:--"At the cost of from one to two thousand pounds of our hard earned money, we devote twelve of the most precious years of your lives to school. There you shall toil, or be supposed to toil; but there you shall not learn one single thing of all those you will most want to know, directly you leave school and enter upon the practical business of life. You will in all probability go into business, but you shall not know where, or how, any article of commerce is produced, or the difference between an export or an import, or the meaning of the word 'capital.' You will very likely settle in a colony, but you shall not know whether Tasmania is part of New South Wales, or _vice versâ_. "Very probably you may become a manufacturer, but you shall not be provided with the means of understanding the working of one of your own steam-engines, or the nature of the raw products you employ; and, when you are asked to buy a patent, you shall not have the slightest means of judging whether the inventor is an impostor who is contravening the elementary principles of science, or a man who will make you as rich as Croesus. "You will very likely get into the House of Commons. You will have to take your share in making laws which may prove a blessing or a curse to millions of men. But you shall not hear one word respecting the political organization of your country; the meaning of the controversy between freetraders and protectionists shall never have been mentioned to you: you shall not so much as know that there are such things as economical laws. "The mental power which will be of most importance in your daily life will be the power of seeing things as they are without regard to authority; and of drawing accurate general conclusions from particular facts. But at school and at college you shall know of no source of truth but authority; nor exercise your reasoning faculty upon anything but deduction from that which is laid down by authority. "You will have to weary your soul with work, and many a time eat your bread in sorrow and in bitterness, and you shall not have learned to take refuge in the great source of pleasure without alloy, the serene resting-place for worn human nature,--the world of art." Said I not rightly that we are a wonderful people? I am quite prepared to allow, that education entirely devoted to these omitted subjects might not be a completely liberal education. But is an education which ignores them all, a liberal education? Nay, is it too much to say that the education which should embrace these subjects and no others, would be a real education, though an incomplete one; while an education which omits them is really not an education at all, but a more or less useful course of intellectual gymnastics? For what does the middle-class school put in the place of all these things which are left out? It substitutes what is usually comprised under the compendious title of the "classics"--that is to say, the languages, the literature, and the history of the ancient Greeks and Romans, and the geography of so much of the world as was known to these two great nations of antiquity. Now, do not expect me to depreciate the earnest and enlightened pursuit of classical learning. I have not the least desire to speak ill of such occupations, nor any sympathy with those who run them down. On the contrary, if my opportunities had lain in that direction, there is no investigation into which I could have thrown myself with greater delight than that of antiquity. What science can present greater attractions than philology? How can a lover of literary excellence fail to rejoice in the ancient masterpieces? And with what consistency could I, whose business lies so much in the attempt to decipher the past, and to build up intelligible forms out of the scattered fragments of long-extinct beings, fail to take a sympathetic, though an unlearned, interest in the labours of a Niebuhr, a Gibbon, or a Grote? Classical history is a great section of the palæontology of man; and I have the same double respect for it as for other kinds of palæontology--that is to say, a respect for the facts which it establishes as for all facts, and a still greater respect for it as a preparation for the discovery of a law of progress. But if the classics were taught as they might be taught--if boys and girls were instructed in Greek and Latin, not merely as languages, but as illustrations of philological science; if a vivid picture of life on the shores of the Mediterranean, two thousand years ago, were imprinted on the minds of scholars; if ancient history were taught, not as a weary series of feuds and fights, but traced to its causes in such men placed under such conditions; if, lastly, the study of the classical books were followed in such a manner as to impress boys with their beauties, and with the grand simplicity of their statement of the everlasting problems of human life, instead of with their verbal and grammatical peculiarities; I still think it as little proper that they should form the basis of a liberal education for our contemporaries, as I should think it fitting to make that sort of palæontology with which I am familiar, the back-bone of modern education. It is wonderful how close a parallel to classical training could be made out of that palæontology to which I refer. In the first place I could get up an osteological primer so arid, so pedantic in its terminology, so altogether distasteful to the youthful mind, as to beat the recent famous production of the head-masters out of the field in all these excellences. Next, I could exercise my boys upon easy fossils, and bring out all their powers of memory and all their ingenuity in the application of my osteo-grammatical rules to the interpretation, or construing, of those fragments. To those who had reached the higher classes, I might supply odd bones to be built up into animals, giving great honour and reward to him who succeeded in fabricating monsters most entirely in accordance with the rules. That would answer to verse-making and essay-writing in the dead languages. To be sure, if a great comparative anatomist were to look at these fabrications he might shake his head, or laugh. But what then? Would such a catastrophe destroy the parallel? What think you would Cicero, or Horace, say to the production of the best sixth form going? And would not Terence stop his ears and run out if he could be present at an English performance of his own plays? Would Hamlet, in the mouths of a set of French actors, who should insist on pronouncing English after the fashion of their own tongue, be more hideously ridiculous? But it will be said that I am forgetting the beauty, and the human interest, which appertain to classical studies. To this I reply that it is only a very strong man who can appreciate the charms of a landscape, as he is toiling up a steep hill, along a bad road. What with short-windedness, stones, ruts, and a pervading sense of the wisdom of rest and be thankful, most of us have little enough sense of the beautiful under these circumstances. The ordinary school-boy is precisely in this case. He finds Parnassus uncommonly steep, and there is no chance of his having much time or inclination to look about him till he gets to the top. And nine times out of ten he does not get to the top. But if this be a fair picture of the results of classical teaching at its best--and I gather from those who have authority to speak on such matters that it is so--what is to be said of classical teaching at its worst, or in other words, of the classics of our ordinary middle-class schools[2]? I will tell you. It means getting up endless forms and rules by heart. It means turning Latin and Greek into English, for the mere sake of being able to do it, and without the smallest regard to the worth, or worthlessness, of the author read. It means the learning of innumerable, not always decent, fables in such a shape that the meaning they once had is dried up into utter trash; and the only impression left upon a boy's mind is, that the people who believed such things must have been the greatest idiots the world ever saw. And it means, finally, that after a dozen years spent at this kind of work, the sufferer shall be incompetent to interpret a passage in an author he has not already got up; that he shall loathe the sight of a Greek or Latin book; and that he shall never open, or think of, a classical writer again, until, wonderful to relate, he insists upon submitting his sons to the same process. These be your gods, O Israel! For the sake of this net result (and respectability) the British father denies his children all the knowledge they might turn to account in life, not merely for the achievement of vulgar success, but for guidance in the great crises of human existence. This is the stone he offers to those whom he is bound by the strongest and tenderest ties to feed with bread. If primary and secondary education are in this unsatisfactory state, what is to be said to the universities? This is an awful subject, and one I almost fear to touch with my unhallowed hands; but I can tell you what those say who have authority to speak. The Rector of Lincoln College, in his lately published, valuable "Suggestions for Academical Organization with especial reference to Oxford," tells us (p. 127):-- "The colleges were, in their origin, endowments, not for the elements of a general liberal education, but for the prolonged study of special and professional faculties by men of riper age. The universities embraced both these objects. The colleges, while they incidentally aided in elementary education, were specially devoted to the highest learning.... "This was the theory of the middle-age university and the design of collegiate foundations in their origin. Time and circumstances have brought about a total change. The colleges no longer promote the researches of science, or direct professional study. Here and there college walls may shelter an occasional student, but not in larger proportions than may be found in private life. Elementary teaching of youths under twenty is now the only function performed by the university, and almost the only object of college endowments. Colleges were homes for the life-study of the highest and most abstruse parts of knowledge. They have become boarding schools in which the elements of the learned languages are taught to youths." If Mr. Pattison's high position, and his obvious love and respect for his university, be insufficient to convince the outside world that language so severe is yet no more than just, the authority of the Commissioners who reported on the University of Oxford in 1850 is open to no challenge. Yet they write:-- "It is generally acknowledged that both Oxford and the country at large suffer greatly from the absence of a body of learned men devoting their lives to the cultivation of science, and to the direction of academical education. "The fact that so few books of profound research emanate from the University of Oxford, materially impairs its character as a seat of learning, and consequently its hold on the respect of the nation." Cambridge can claim no exemption from the reproaches addressed to Oxford. And thus there seems no escape from the admission that what we fondly call our great seats of learning are simply "boarding schools" for bigger boys; that learned men are not more numerous in them than out of them; that the advancement of knowledge is not the object of fellows of colleges; that, in the philosophic calm and meditative stillness of their greenswarded courts, philosophy does not thrive, and meditation bears few fruits. It is my great good fortune to reckon amongst my friends resident members of both universities, who are men of learning and research, zealous cultivators of science, keeping before their minds a noble ideal of a university, and doing their best to make that ideal a reality; and, to me, they would necessarily typify the universities, did not the authoritative statements I have quoted compel me to believe that they are exceptional, and not representative men. Indeed, upon calm consideration, several circumstances lead me to think that the Rector of Lincoln College and the Commissioners cannot be far wrong. I believe there can be no doubt that the foreigner who should wish to become acquainted with the scientific, or the literary, activity of modern England, would simply lose his time and his pains if he visited our universities with that object. And, as for works of profound research on any subject, and, above all, in that classical lore for which the universities profess to sacrifice almost everything else, why, a third-rate, poverty-stricken German university turns out more produce of that kind in one year, than our vast and wealthy foundations elaborate in ten. Ask the man who is investigating any question, profoundly and thoroughly--be it historical, philosophical, philological, physical, literary, or theological; who is trying to make himself master of any abstract subject (except, perhaps, political economy and geology, both of which are intensely Anglican sciences) whether he is not compelled to read half a dozen times as many German, as English, books? And whether, of these English books, more than one in ten is the work of a fellow of a college, or a professor of an English university? Is this from any lack of power in the English as compared with the German mind? The countrymen of Grote and of Mill, of Faraday, of Robert Brown, of Lyell, and of Darwin, to go no further back than the contemporaries of men of middle age, can afford to smile at such a suggestion. England can show now, as she has been able to show in every generation since civilization spread over the West, individual men who hold their own against the world, and keep alive the old tradition of her intellectual eminence. But, in the majority of cases, these men are what they are in virtue of their native intellectual force, and of a strength of character which will not recognise impediments. They are not trained in the courts of the Temple of Science, but storm the walls of that edifice in all sorts of irregular ways, and with much loss of time and power, in order to obtain their legitimate positions. Our universities not only do not encourage such men; do not offer them positions, in which it should be their highest duty to do, thoroughly, that which they are most capable of doing; but, as far as possible, university training shuts out of the minds of those among them, who are subjected to it, the prospect that there is anything in the world for which they are specially fitted. Imagine the success of the attempt to still the intellectual hunger any of the men I have mentioned, by putting before him, as the object of existence, the successful mimicry of the measure of a Greek song, or the roll of Ciceronian prose! Imagine how much success would be likely to attend the attempt to persuade such men, that the education which leads to perfection in such elegancies is alone to be called culture; while the facts of history, the process of thought, the conditions of moral and social existence, and the laws of physical nature, are left to be dealt with as they may, by outside barbarians! It is not thus that the German universities, from being beneath notice a century ago, have become what they are now--the most intensely cultivated and the most productive intellectual corporations the world has ever seen. The student who repairs to them sees in the list of classes and of professors a fair picture of the world of knowledge. Whatever he needs to know there is some one ready to teach him, some one competent to discipline him in the way of learning; whatever his special bent, let him but be able and diligent, and in due time he shall find distinction and a career. Among his professors, he sees men whose names are known and revered throughout the civilized world; and their living example infects him with a noble ambition, and a love for the spirit of work. The Germans dominate the intellectual world by virtue of the same simple secret as that which made Napoleon the master of old Europe. They have declared _la carrière ouverte aux talents_, and every Bursch marches with a professor's gown in his knapsack. Let him become a great scholar, or man of science, and ministers will compete for his services. In Germany, they do not leave the chance of his holding the office he would render illustrious to the tender mercies of a hot canvass, and the final wisdom of a mob of country parsons. In short, in Germany, the universities are exactly what the Rector of Lincoln and the Commissioners tell us the English universities are not; that is to say, corporations "of learned men devoting their lives to the cultivation of science, and the direction of academical education." They are not "boarding schools for youths," nor clerical seminaries; but institutions for the higher culture of men, in which the theological faculty is of no more importance, or prominence, than the rest; and which are truly "universities," since they strive to represent and embody the totality of human knowledge, and to find room for all forms of intellectual activity. May zealous and clear-headed reformers like Mr. Pattison succeed in their noble endeavours to shape our universities towards some such ideal as this, without losing what is valuable and distinctive in their social tone! But until they have succeeded, a liberal education will be no more obtainable in our Oxford and Cambridge Universities than in our public schools. If I am justified in my conception of the ideal of a liberal education; and if what I have said about the existing educational institutions of the country is also true, it is clear that the two have no sort of relation to one another; that the best of our schools and the most complete of our university trainings give but a narrow, one-sided, and essentially illiberal education--while the worst give what is really next to no education at all. The South London Working-Men's College could not copy any of these institutions if it would. I am bold enough to express the conviction that it ought not if it could. For what is wanted is the reality and not the mere name of a liberal education; and this College must steadily set before itself the ambition to be able to give that education sooner or later. At present we are but beginning, sharpening our educational tools, as it were, and, except a modicum of physical science, we are not able to offer much more than is to be found in an ordinary school. Moral and social science--one of the greatest and most fruitful of our future classes, I hope--at present lacks only one thing in our programme, and that is a teacher. A considerable want, no doubt; but it must be recollected that it is much better to want a teacher than to want the desire to learn. Further, we need what, for want of a better name, I must call Physical Geography. What I mean is that which the Germans call "_Erdkunde_." It is a description of the earth, of its place and relation to other bodies; of its general structure, and of its great features--winds, tides, mountains, plains; of the chief forms of the vegetable and animal worlds, of the varieties of man. It is the peg upon which the greatest quantity of useful and entertaining scientific information can be suspended. Literature is not upon the College programme; but I hope some day to see it there. For literature is the greatest of all sources of refined pleasure, and one of the great uses of a liberal education is to enable us to enjoy that pleasure. There is scope enough for the purposes of liberal education in the study of the rich treasures of our own language alone. All that is needed is direction, and the cultivation of a refined taste by attention to sound criticism. But there is no reason why French and German should not be mastered sufficiently to read what is worth reading in those languages, with pleasure and with profit. And finally, by-and-by, we must have History; treated not as a succession of battles and dynasties; not as a series of biographies; not as evidence that Providence has always been on the side of either Whigs or Tories; but as the development of man in times past, and in other conditions than our own. But, as it is one of the principles of our College to be self-supporting, the public must lead, and we must follow, in these matters. If my hearers take to heart what I have said about liberal education, they will desire these things, and I doubt not we shall be able to supply them. But we must wait till the demand is made. FOOTNOTE: [2] For a justification of what is here said about these schools, see that valuable book, "Essays on a Liberal Education," _passim_. IV. SCIENTIFIC EDUCATION: NOTES OF AN AFTER-DINNER SPEECH. [MR. THACKERAY, talking of after-dinner speeches, has lamented that "one never can recollect the fine things one thought of in the cab," in going to the place of entertainment. I am not aware that there are any "fine things" in the following pages, but such as there are stand to a speech which really did get itself spoken, at the hospitable table of the Liverpool Philomathic Society, more or less in the position of what "one thought of in the cab."] The introduction of scientific training into the general education of the country is a topic upon which I could not have spoken, without some more or less apologetic introduction, a few years ago. But upon this, as upon other matters, public opinion has of late undergone a rapid modification. Committees of both Houses of the Legislature have agreed that something must be done in this direction, and have even thrown out timid and faltering suggestions as to what should be done; while at the opposite pole of society, committees of working-men have expressed their conviction that scientific training is the one thing needful for their advancement, whether as men, or as workmen. Only the other day, it was my duty to take part in the reception of a deputation of London working men, who desired to learn from Sir Roderick Murchison, the Director of the Royal School of Mines, whether the organization of the Institution in Jermyn Street could be made available for the supply of that scientific instruction, the need of which could not have been apprehended, or stated, more clearly than it was by them. The heads of colleges in our great Universities (who have not the reputation of being the most mobile of persons) have, in several cases, thought it well that, out of the great number of honours and rewards at their disposal, a few should hereafter be given to the cultivators of the physical sciences. Nay, I hear that some colleges have even gone so far as to appoint one, or, may be, two special tutors for the purpose of putting the facts and principles of physical science before the undergraduate mind. And I say it with gratitude and great respect for those eminent persons, that the head masters of our public schools, Eton, Harrow, Winchester, have addressed themselves to the problem of introducing instruction in physical science among the studies of those great educational bodies, with much honesty of purpose and enlightenment of understanding; and I live in hope that, before long, important changes in this direction will be carried into effect in those strongholds of ancient prescription. In fact, such changes have already been made, and physical science, even now, constitutes a recognised element of the school curriculum in Harrow and Rugby, whilst I understand that ample preparations for such studies are being made at Eton and elsewhere. Looking at these facts, I might perhaps spare myself the trouble of giving any reasons for the introduction of physical science into elementary education; yet I cannot but think that it may be well, if I place before you some considerations which, perhaps, have hardly received full attention. At other times, and in other places, I have endeavoured to state the higher and more abstract arguments, by which the study of physical science may be shown to be indispensable to the complete training of the human mind; but I do not wish it to be supposed that, because I happen to be devoted to more or less abstract and "unpractical" pursuits, I am insensible to the weight which ought to be attached to that which has been said to be the English conception of Paradise--"namely, getting on." I look upon it, that "getting on" is a very important matter indeed. I do not mean merely for the sake of the coarse and tangible results of success, but because humanity is so constituted that a vast number of us would never be impelled to those stretches of exertion which make us wiser and more capable men, if it were not for the absolute necessity of putting on our faculties all the strain they will bear, for the purpose of "getting on" in the most practical sense. Now the value of a knowledge of physical science as a means of getting on, is indubitable. There are hardly any of our trades, except the merely huckstering ones, in which some knowledge of science may not be directly profitable to the pursuer of that occupation. As industry attains higher stages of its development, as its processes become more complicated and refined, and competition more keen, the sciences are dragged in, one by one, to take their share in the fray; and he who can best avail himself of their help is the man who will come out uppermost in that struggle for existence which goes on as fiercely beneath the smooth surface of modern society, as among the wild inhabitants of the woods. But, in addition to the bearing of science on ordinary practical life, let me direct your attention to its immense influence on several of the professions. I ask any one who has adopted the calling of an engineer, how much time he lost when he left school, because he had to devote himself to pursuits which were absolutely novel and strange, and of which he had not obtained the remotest conception from his instructors? He had to familiarize himself with ideas of the course and powers of Nature, to which his attention had never been directed during his school-life, and to learn, for the first time, that a world of facts lies outside and beyond the world of words. I appeal to those who know what Engineering is, to say how far I am right in respect to that profession; but with regard to another, of no less importance, I shall venture to speak of my own knowledge. There is no one of who may not at any moment be thrown, bound hand and foot by physical incapacity, into the hands of a medical practitioner. The chances of life and death for all and each of us may, at any moment, depend on the skill with which that practitioner is able to make out what is wrong in our bodily frames, and on his ability to apply the proper remedy to the defect. The necessities of modern life are such, and the class from which the medical profession is chiefly recruited is so situated, that few medical men can hope to spend more than three or four, or it may be five, years in the pursuit of those studies which are immediately germane to physic. How is that all too brief period spent at present? I speak as an old examiner, having served some eleven or twelve years in that capacity in the University of London, and therefore having a practical acquaintance with the subject; but I might fortify myself by the authority of the President of the College of Surgeons, Mr. Quain, whom I heard the other day in an admirable address (the Hunterian Oration) deal fully and wisely with this very topic[3]. A young man commencing the study of medicine is at once required to endeavour to make an acquaintance with a number of sciences, such as Physics, as Chemistry, as Botany, as Physiology, which are absolutely and entirely strange to him, however excellent his so-called education at school may have been. Not only is he devoid of all apprehension of scientific conceptions, not only does he fail to attach any meaning to the words "matter," "force," or "law" in their scientific senses, but, worse still, he has no notion of what it is to come into contact with nature, or to lay his mind alongside of a physical fact, and try to conquer it, in the way our great naval hero told his captains to master their enemies. His whole mind has been given to books, and I am hardly exaggerating if I say that they are more real to him than Nature. He imagines that all knowledge can be got out of books, and rests upon the authority of some master or other; nor does he entertain any misgiving that the method of learning which led to proficiency in the rules of grammar, will suffice to lead him to a mastery of the laws of Nature. The youngster, thus unprepared for serious study, is turned loose among his medical studies, with the result, in nine cases out of ten, that the first year of his curriculum is spent in learning how to learn. Indeed, he is lucky, if at the end of the first year, by the exertions of his teachers and his own industry, he has acquired even that art of arts. After which there remain not more than three, or perhaps four, years for the profitable study of such vast sciences as Anatomy, Physiology, Therapeutics, Medicine, Surgery, Obstetrics, and the like, upon his knowledge or ignorance of which it depends whether the practitioner shall diminish, or increase, the bills of mortality. Now what is it but the preposterous condition of ordinary school education which prevents a young man of seventeen, destined for the practice of medicine, from being fully prepared for the study of nature; and from coming to the medical school, equipped with that preliminary knowledge of the principles of Physics, of Chemistry, and of Biology, upon which he has now to waste one of the precious years, every moment of which ought to be given to those studies which bear directly upon the knowledge of his profession? There is another profession, to the members of which, I think, a certain preliminary knowledge of physical science might be quite as valuable as to the medical man. The practitioner of medicine sets before himself the noble object of taking care of man's bodily welfare; but the members of this other profession undertake to "minister to minds diseased," and, so far as may be, to diminish sin and soften sorrow. Like the medical profession, the clerical, of which I now speak, rests its power to heal upon its knowledge of the order of the universe--upon certain theories of man's relation to that which lies outside him. It is not my business to express any opinion about these theories. I merely wish to point out that, like all other theories, they are professedly based upon matter of fact. Thus the clerical profession has to deal with the facts of Nature from a certain point of view; and hence it comes into contact with that of the man of science, who has to treat the same facts from another point of view. You know how often that contact is to be described as collision, or violent friction; and how great the heat, how little the light, which commonly results from it. In the interests of fair play, to say nothing of those of mankind, I ask, Why do not the clergy as a body acquire, as a part of their preliminary education, some such tincture of physical science as will put them in a position to understand the difficulties in the way of accepting their theories, which are forced upon the mind of every thoughtful and intelligent man, who has taken the trouble to instruct himself in the elements of natural knowledge? Some time ago I attended a large meeting of the clergy, for the purpose of delivering an address which I had been invited to give. I spoke of some of the most elementary facts in physical science, and of the manner in which they directly contradict certain of the ordinary teachings of the clergy. The result was, that, after I had finished, one section of the assembled ecclesiastics attacked me with all the intemperance of pious zeal, for stating facts and conclusions which no competent judge doubts; while, after the first speakers had subsided, amidst the cheers of the great majority of their colleagues, the more rational minority rose to tell me that I had taken wholly superfluous pains, that they already knew all about what I had told them, and perfectly agreed with me. A hard-headed friend of mine, who was present, put the not unnatural question, "Then why don't you say so in your pulpits?" to which inquiry I heard no reply. In fact the clergy are at present divisible into three sections: an immense body who are ignorant and speak out; a small proportion who know and are silent; and a minute minority who know and speak according to their knowledge. By the clergy, I mean especially the Protestant clergy. Our great antagonist--I speak as a man of science--the Roman Catholic Church, the one great spiritual organization which is able to resist, and must, as a matter of life and death, resist, the progress of science and modern civilization, manages her affairs much better. It was my fortune some time ago to pay a visit to one of the most important of the institutions in which the clergy of the Roman Catholic Church in these islands are trained; and it seemed to me that the difference between these men and the comfortable champions of Anglicanism and of Dissent, was comparable to the difference between our gallant Volunteers and the trained veterans of Napoleon's Old Guard. The Catholic priest is trained to know his business, and do it effectually. The professors of the college in question, learned, zealous, and determined men, permitted me to speak frankly with them. We talked like outposts of opposed armies during a truce--as friendly enemies; and when I ventured to point out the difficulties their students would have to encounter from scientific thought, they replied: "Our Church has lasted many ages, and has passed safely through many storms. The present is but a new gust of the old tempest, and we do not turn out our young men less fitted to weather it, than they have been, in former times, to cope with the difficulties of those times. The heresies of the day are explained to them by their professors of philosophy and science, and they are taught how those heresies are to be met." I heartily respect an organization which faces its enemies in this way; and I wish that all ecclesiastical organizations were in as effective a condition. I think it would be better, not only for them, but for us. The army of liberal thought is, at present, in very loose order; and many a spirited free-thinker makes use of his freedom mainly to vent nonsense. We should be the better for a vigorous and watchful enemy to hammer us into cohesion and discipline; and I, for one, lament that the bench of Bishops cannot show a man of the calibre of Butler of the "Analogy," who, if he were alive, would make short work of much of the current _à priori_ "infidelity." I hope you will consider that the arguments I have now stated, even if there were no better ones, constitute a sufficient apology for urging the introduction of science into schools. The next question to which I have to address myself is, What sciences ought to be thus taught? And this is one of the most important of questions, because my side (I am afraid I am a terribly candid friend) sometimes spoils its cause by going in for too much. There are other forms of culture beside physical science; and I should be profoundly sorry to see the fact forgotten, or even to observe a tendency to starve, or cripple, literary, or æsthetic, culture for the sake of science. Such a narrow view of the nature of education has nothing to do with my firm conviction that a complete and thorough scientific culture ought to be introduced into all schools. By this, however, I do not mean that every schoolboy should be taught everything in science. That would be a very absurd thing to conceive, and a very mischievous thing to attempt. What I mean is, that no boy nor girl should leave school without possessing a grasp of the general character of science, and without having been disciplined, more or less, in the methods of all sciences; so that, when turned into the world to make their own way, they shall be prepared to face scientific problems, not by knowing at once the conditions of every problem, or by being able at once to solve it; but by being familiar with the general current of scientific thought, and by being able to apply the methods of science in the proper way, when they have acquainted themselves with the conditions of the special problem. That is what I understand by scientific education. To furnish a boy with such an education, it is by no means necessary that he should devote his whole school existence to physical science: in fact, no one would lament so one-sided a proceeding more than I. Nay more, it is not necessary for him to give up more than a moderate share of his time to such studies, if they be properly selected and arranged, and if he be trained in them in a fitting manner. I conceive the proper course to be somewhat as follows. To begin with, let every child be instructed in those general views of the phenomena of Nature for which we have no exact English name. The nearest approximation to a name for what I mean, which we possess, is "physical geography." The Germans have a better, "Erdkunde," ("earth knowledge" or "geology" in its etymological sense,) that is to say, a general knowledge of the earth, and what is on it, in it, and about it. If any one who has had experience of the ways of young children will call to mind their questions, he will find that so far as they can be put into any scientific category, they come under this head of "Erdkunde." The child asks, "What is the moon, and why does it shine?" "What is this water, and where does it run?" "What is the wind?" "What makes the waves in the sea?" "Where does this animal live, and what is the use of that plant?" And if not snubbed and stunted by being told not to ask foolish questions, there is no limit to the intellectual craving of a young child; nor any bounds to the slow, but solid, accretion of knowledge and development of the thinking faculty in this way. To all such questions, answers which are necessarily incomplete, though true as far as they go, may be given by any teacher whose ideas represent real knowledge and not mere book learning; and a panoramic view of Nature, accompanied by a strong infusion of the scientific habit of mind, may thus be placed within the reach of every child of nine or ten. After this preliminary opening of the eyes to the great spectacle of the daily progress of Nature, as the reasoning faculties of the child grow, and he becomes familiar with the use of the tools of knowledge--reading, writing, and elementary mathematics--he should pass on to what is, in the more strict sense, physical science. Now there are two kinds of physical science: the one regards form and the relation of forms to one another; the other deals with causes and effects. In many of what we term our sciences, these two kinds are mixed up together; but systematic botany is a pure example of the former kind, and physics of the latter kind, of science. Every educational advantage which training in physical science can give is obtainable from the proper study of these two; and I should be contented, for the present, if they, added to our "Erdkunde," furnished the whole of the scientific curriculum of schools. Indeed I conceive it would be one of the greatest boons which could be conferred upon England, if henceforward every child in the country were instructed in the general knowledge of the things about it, in the elements of physics, and of botany. But I should be still better pleased if there could be added somewhat of chemistry, and an elementary acquaintance with human physiology. So far as school education is concerned, I want to go no further just now; and I believe that such instruction would make an excellent introduction to that preparatory scientific training which, as I have indicated, is so essential for the successful pursuit of our most important professions. But this modicum of instruction must be so given as to ensure real knowledge and practical discipline. If scientific education is to be dealt with as mere bookwork, it will be better not to attempt it, but to stick to the Latin Grammar, which makes no pretence to be anything but bookwork. If the great benefits of scientific training are sought, it is essential that such training should be real: that is to say, that the mind of the scholar should be brought into direct relation with fact, that he should not merely be told a thing, but made to see by the use of his own intellect and ability that the thing is _so_ and no otherwise. The great peculiarity of scientific training, that in virtue of which it cannot be replaced by any other discipline whatsoever, is this bringing of the mind directly into contact with fact, and practising the intellect in the completest form of induction; that is to say, in drawing conclusions from particular facts made known by immediate observation of Nature. The other studies which enter into ordinary education do not discipline the mind in this way. Mathematical training is almost purely deductive. The mathematician starts with a few simple propositions, the proof of which is so obvious that they are called self-evident, and the rest of his work consists of subtle deductions from them. The teaching of languages, at any rate as ordinarily practised, is of the same general nature,--authority and tradition furnish the data, and the mental operations of the scholar are deductive. Again: if history be the subject of study, the facts are still taken upon the evidence of tradition and authority. You cannot make a boy see the battle of Thermopylæ for himself, or know, of his own knowledge, that Cromwell once ruled England. There is no getting into direct contact with natural fact by this road; there is no dispensing with authority, but rather a resting upon it. In all these respects, science differs from other educational discipline, and prepares the scholar for common life. What have we to do in every-day life? Most of the business which demands our attention is matter of fact, which needs, in the first place, to be accurately observed or apprehended; in the second, to be interpreted by inductive and deductive reasonings, which are altogether similar in their nature to those employed in science. In the one case, as in the other, whatever is taken for granted is so taken at one's own peril; fact and reason are the ultimate arbiters, and patience and honesty are the great helpers out of difficulty. But if scientific training is to yield its most eminent results, it must, I repeat, be made practical. That is to say, in explaining to a child the general phenomena of Nature, you must, as far as possible, give reality to your teaching by object-lessons; in teaching him botany, he must handle the plants and dissect the flowers for himself; in teaching him physics and chemistry, you must not be solicitous to fill him with information, but you must be careful that what he learns he knows of his own knowledge. Don't be satisfied with telling him that a magnet attracts iron. Let him see that it does; let him feel the pull of the one upon the other for himself. And, especially, tell him that it is his duty to doubt until he is compelled, by the absolute authority of Nature, to believe that which is written in books. Pursue this discipline carefully and conscientiously, and you may make sure that, however scanty may be the measure of information which you have poured into the boy's mind, you have created an intellectual habit of priceless value in practical life. One is constantly asked, When should this scientific education be commenced? I should say with the dawn of intelligence. As I have already said, a child seeks for information about matters of physical science as soon as it begins to talk. The first teaching it wants is an object-lesson of one sort or another; and as soon as it is fit for systematic instruction of any kind, it is fit for a modicum of science. People talk of the difficulty of teaching young children such matters, and in the same breath insist upon their learning their Catechism, which contains propositions far harder to comprehend than anything in the educational course I have proposed. Again, I am incessantly told that we, who advocate the introduction of science into schools, make no allowance for the stupidity of the average boy or girl; but, in my belief, that stupidity, in nine cases out of ten, "_fit, non nascitur_," and is developed by a long process of parental and pedagogic repression of the natural intellectual appetites, accompanied by a persistent attempt to create artificial ones for food which is not only tasteless, but essentially indigestible. Those who urge the difficulty of instructing young people in science are apt to forget another very important condition of success--important in all kinds of teaching, but most essential, I am disposed to think, when the scholars are very young. This condition is, that the teacher should himself really and practically know his subject. If he does, he will be able to speak of it in the easy language, and with the completeness of conviction, with which he talks of any ordinary every-day matter. If he does not, he will be afraid to wander beyond the limits of the technical phraseology which he has got up; and a dead dogmatism, which oppresses, or raises opposition, will take the place of the lively confidence, born of personal conviction, which cheers and encourages the eminently sympathetic mind of childhood. I have already hinted that such scientific training as we seek for may be given without making any extravagant claim upon the time now devoted to education. We ask only for "a most favoured nation" clause in our treaty with the schoolmaster; we demand no more than that science shall have as much time given to it as any other single subject--say four hours a week in each class of an ordinary school. For the present, I think men of science would be well content with such an arrangement as this; but, speaking for myself, I do not pretend to believe that such an arrangement can be, or will be, permanent. In these times the educational tree seems to me to have its roots in the air, its leaves and flowers in the ground; and, I confess, I should very much like to turn it upside down, so that its roots might be solidly embedded among the facts of Nature, and draw thence a sound nutriment for the foliage and fruit of literature and of art. No educational system can have a claim to permanence, unless it recognises the truth that education has two great ends to which everything else must be subordinated. The one of these is to increase knowledge; the other is to develop the love of right and the hatred of wrong. With wisdom and uprightness a nation can make its way worthily, and beauty will follow in the footsteps of the two, even if she be not specially invited; while there is perhaps no sight in the whole world more saddening and revolting than is offered by men sunk in ignorance of everything but what other men have written; seemingly devoid of moral belief or guidance; but with the sense of beauty so keen, and the power of expression so cultivated, that their sensual caterwauling may be almost mistaken for the music of the spheres. At present, education is almost entirely devoted to the cultivation of the power of expression, and of the sense of literary beauty. The matter of having anything to say, beyond a hash of other people's opinions, or of possessing any criterion of beauty, so that we may distinguish between the Godlike and the devilish, is left aside as of no moment. I think I do not err in saying that if science were made the foundation of education, instead of being, at most, stuck on as cornice to the edifice, this state of things could not exist. In advocating the introduction of physical science as a leading element in education, I by no means refer only to the higher schools. On the contrary, I believe that such a change is even more imperatively called for in those primary schools, in which the children of the poor are expected to turn to the best account the little time they can devote to the acquisition of knowledge. A great step in this direction has already been made by the establishment of science-classes under the Department of Science and Art,--a measure which came into existence unnoticed, but which will, I believe, turn out to be of more importance to the welfare of the people, than many political changes, over which the noise of battle has rent the air. Under the regulations to which I refer, a schoolmaster can set up a class in one or more branches of science; his pupils will be examined, and the State will pay him, at a certain rate, for all who succeed in passing. I have acted as an examiner under this system from the beginning of its establishment, and this year I expect to have not fewer than a couple of thousand sets of answers to questions in Physiology, mainly from young people of the artisan class, who have been taught in the schools which are now scattered all over Great Britain and Ireland. Some of my colleagues, who have to deal with subjects such as Geometry, for which the present teaching power is better organized, I understand are likely to have three or four times as many papers. So far as my own subjects are concerned, I can undertake to say that a great deal of the teaching, the results of which are before me in these examinations, is very sound and good; and I think it is in the power of the examiners, not only to keep up the present standard, but to cause an almost unlimited improvement. Now what does this mean? It means that by holding out a very moderate inducement, the masters of primary schools in many parts of the country have been led to convert them into little foci of scientific instruction; and that they and their pupils have contrived to find, or to make, time enough to carry out this object with a very considerable degree of efficiency. That efficiency will, I doubt not, be very much increased as the system becomes known and perfected, even with the very limited leisure left to masters and teachers on week-days. And this leads me to ask, Why should scientific teaching be limited to week-days? Ecclesiastically-minded persons are in the habit of calling things they do not like by very hard names, and I should not wonder if they brand the proposition I am about to make as blasphemous, and worse. But, not minding this, I venture to ask, Would there really be anything wrong in using part of Sunday for the purpose of instructing those who have no other leisure, in a knowledge of the phenomena of Nature, and of man's relation to nature? I should like to see a scientific Sunday-school in every parish, not for the purpose of superseding any existing means of teaching the people the things that are for their good, but side by side with them. I cannot but think that there is room for all of us to work in helping to bridge over the great abyss of ignorance which lies at our feet. And if any of the ecclesiastical persons to whom I have referred, object that they find it derogatory to the honour of the God whom they worship, to awaken the minds of the young to the infinite wonder and majesty of the works which they proclaim His, and to teach them those laws which must needs be His laws, and therefore of all things needful for man to know--I can only recommend them to be let blood and put on low diet. There must be something very wrong going on in the instrument of logic, if it turns out such conclusions from such premisses. FOOTNOTE: [3] Mr. Quain's words (_Medical Times and Gazette_, February 20) are:--"A few words as to our special Medical course of instruction and the influence upon it of such changes in the elementary schools as I have mentioned. The student now enters at once upon several sciences--physics, chemistry, anatomy, physiology, botany, pharmacy, therapeutics--all these, the facts and the language and the laws of each, to be mastered in eighteen months. Up to the beginning of the Medical course many have learned little. We cannot claim anything better than the Examiner of the University of London and the Cambridge Lecturer have reported for their Universities. Supposing that at school young people had acquired some exact elementary knowledge in physics, chemistry, and a branch of natural history--say botany--with the physiology connected with it, they would then have gained necessary knowledge, with some practice in inductive reasoning. The whole studies are processes of observation and induction--the best discipline of the mind for the purposes of life--for our purposes not less than any. 'By such study (says Dr. Whewell) of one or more departments of inductive science the mind may escape from the thraldom of mere words.' By that plan the burden of the early Medical course would be much lightened, and more time devoted to practical studies, including Sir Thomas Watson's 'final and supreme stage' of the knowledge of Medicine." V. ON THE EDUCATIONAL VALUE OF THE NATURAL HISTORY SCIENCES. The subject to which I have to beg your attention during the ensuing hour is "The Relation of Physiological Science to other branches of Knowledge." Had circumstances permitted of the delivery, in their strict logical order, of that series of discourses of which the present lecture is a member, I should have preceded my friend and colleague Mr. Henfrey, who addressed you on Monday last; but while, for the sake of that order, I must beg you to suppose that this discussion of the Educational bearings of Biology in general _does_ precede that of Special Zoology and Botany, I am rejoiced to be able to take advantage of the light thus already thrown upon the tendency and methods of Physiological Science. Regarding Physiological Science, then, in its widest sense--as the equivalent of _Biology_--the Science of Individual Life--we have to consider in succession: 1. Its position and scope as a branch of knowledge. 2. Its value as a means of mental discipline. 3. Its worth as practical information. And lastly, 4. At what period it may best be made a branch of Education. Our conclusions on the first of these heads must depend, of course, upon the nature of the subject-matter of Biology; and I think a few preliminary considerations will place before you in a clear light the vast difference which exists between the living bodies with which Physiological science is concerned, and the remainder of the universe;--between the phænomena of Number and Space, of Physical and of Chemical force, on the one hand, and those of Life on the other. The mathematician, the physicist, and the chemist contemplate things in a condition of rest; they look upon a state of equilibrium as that to which all bodies normally tend. The mathematician does not suppose that a quantity will alter, or that a given point in space will change its direction with regard to another point, spontaneously. And it is the same with the physicist. When Newton saw the apple fall, he concluded at once that the act of falling was not the result of any power inherent in the apple, but that it was the result of the action of something else on the apple. In a similar manner, all physical force is regarded as the disturbance of an equilibrium to which things tended before its exertion,--to which they will tend again after its cessation. The chemist equally regards chemical change in a as the effect of the action of something external to the body changed. A chemical compound once formed would persist for ever, if no alteration took place in surrounding conditions. But to the student of Life the aspect of nature is reversed. Here, incessant, and, so far as we know, spontaneous change is the rule, rest the exception--the anomaly to be accounted for. Living things have no inertia, and tend to no equilibrium. Permit me, however, to give more force and clearness to these somewhat abstract considerations, by an illustration or two. Imagine a vessel full of water, at the ordinary temperature, in an atmosphere saturated with vapour. The _quantity_ and the _figure_ of that water will not change, so far as we know, for ever. Suppose a lump of gold be thrown into the vessel--motion and disturbance of figure exactly proportional to the momentum of the gold will take place. But after a time the effects of this disturbance will subside--equilibrium will be restored, and the water will return to its passive state. Expose the water to cold--it will solidify--and in so doing its particles will arrange themselves in definite crystalline shapes. But once formed, these crystals change no further. Again, substitute for the lump of gold some substance capable of entering into chemical relations with the water:--say, a mass of that substance which is called "protein"--the substance of flesh:--a very considerable disturbance of equilibrium will take place--all sorts of chemical compositions and decompositions will occur; but in the end, as before, the result will be the resumption of a condition of rest. Instead of such a mass of _dead_ protein, however, take a particle of _living_ protein--one of those minute microscopic living things which throng our pools, and are known as Infusoria--such a creature, for instance, as an Euglena, and place it in our vessel of water. It is a round mass provided with a long filament, and except in this peculiarity of shape, presents no appreciable physical or chemical difference whereby it might be distinguished from the particle of dead protein. But the difference in the phænomena to which it will give rise is immense: in the first place it will develop a vast quantity of physical force--cleaving the water in all directions with considerable rapidity by means of the vibrations of the long filament or cilium. Nor is the amount of chemical energy which the little creature possesses less striking. It is a perfect laboratory in itself, and it will act and react upon the water and the matters contained therein; converting them into new compounds resembling its own substance, and, at the same time, giving up portions of its own substance which have become effete. Furthermore, the Euglena will increase in size; but this increase is by no means unlimited, as the increase of a crystal might be. After it has grown to a certain extent it divides, and each portion assumes the form of the original, and proceeds to repeat the process of growth and division. Nor is this all. For after a series of such divisions and subdivisions, these minute points assume a totally new form, lose their long tails--round themselves, and secrete a sort of envelope or box, in which they remain shut up for a time, eventually to resume, directly or indirectly, their primitive mode of existence. Now, so far as we know, there is no natural limit to the existence of the Euglena, or of any other living germ. A living species once launched into existence tends to live for ever. Consider how widely different this living particle is from the dead atoms with which the physicist and chemist have to do! The particle of gold falls to the bottom and rests--the particle of dead protein decomposes and disappears--it also rests: but the _living_ protein mass neither tends to exhaustion of its forces nor to any permanency of form, but is essentially distinguished as a disturber of equilibrium so far as force is concerned,--as undergoing continual metamorphosis and change, in point of form. Tendency to equilibrium of force and to permanency of form then, are the characters of that portion of the universe which does not live--the domain of the chemist and physicist. Tendency to disturb existing equilibrium,--to take on forms which succeed one another in definite cycles, is the character of the living world. What is the cause of this wonderful difference between the dead particle and the living particle of matter appearing in other respects identical? that difference to which we give the name of Life? I, for one, cannot tell you. It may be that, by and by, philosophers will discover some higher laws of which the facts of life are particular cases--very possibly they will find out some bond between physico-chemical phænomena on the one hand, and vital phænomena on the other. At present, however, we assuredly know of none; and I think we shall exercise a wise humility in confessing that, for us at least, this successive assumption of different states--(external conditions remaining the same)--this _spontaneity of action_--if I may use a term which implies more than I would be answerable for--which constitutes so vast and plain a practical distinction between living bodies and those which do not live, is an ultimate fact; indicating as such, the existence of a broad line of demarcation between the subject-matter of Biological and that of all other sciences. For I would have it understood that this simple Euglena is the type of _all_ living things, so far as the distinction between these and inert matter is concerned. That cycle of changes, which is constituted by perhaps not more than two or three steps in the Euglena, is as clearly manifested in the multitudinous stages through which the germ of an oak or of a man passes. Whatever forms the Living Being may take on, whether simple or complex, _production_, _growth_, _reproduction_, are the phænomena which distinguish it from that which does not live. If this be true, it is clear that the student, in passing from the physico-chemical to the physiological sciences, enters upon a totally new order of facts; and it will next be for us to consider how far these new facts involve _new_ methods, or require a modification of those with which he is already acquainted. Now a great deal is said about the peculiarity of the scientific method in general, and of the different methods which are pursued in the different sciences. The Mathematics are said to have one special method; Physics another, Biology a third, and so forth. For my own part, I must confess that I do not understand this phraseology. So far as I can arrive at any clear comprehension of the matter, Science is not, as many would seem to suppose, a modification of the black art, suited to the tastes of the nineteenth century, and flourishing mainly in consequence of the decay of the Inquisition. Science is, I believe, nothing but _trained and organized common sense_, differing from the latter only as a veteran may differ from a raw recruit: and its methods differ from those of common sense only so far as the guardsman's cut and thrust differ from the manner in which a savage wields his club. The primary power is the same in each case, and perhaps the untutored savage has the more brawny arm of the two. The _real_ advantage lies in the point and polish of the swordsman's weapon; in the trained eye quick to spy out the weakness of the adversary; in the ready hand prompt to follow it on the instant. But after all, the sword exercise is only the hewing and poking of the clubman developed and perfected. So, the vast results obtained by Science are won by no mystical faculties, by no mental processes, other than those which are practised by every one of us, in the humblest and meanest affairs of life. A detective policeman discovers a burglar from the marks made by his shoe, by a mental process identical with that by which Cuvier restored the extinct animals of Montmartre from fragments of their bones. Nor does that process of induction and deduction by which a lady, finding a stain of a peculiar kind upon her dress, concludes that somebody has upset the inkstand thereon, differ in any way, in kind, from that by which Adams and Leverrier discovered a new planet. The man of science, in fact, simply uses with scrupulous exactness, the methods which we all, habitually and at every moment, use carelessly; and the man of business must as much avail himself of the scientific method--must be as truly a man of science--as the veriest bookworm of us all; though I have no doubt that the man of business will find himself out to be a philosopher with as much surprise as M. Jourdain exhibited, when he discovered that he had been all his life talking prose. If, however, there be no real difference between the methods of science and those of common life, it would seem, on the face of the matter, highly improbable that there should be any difference between the methods of the different sciences; nevertheless, it is constantly taken for granted, that there is a very wide difference between the Physiological and other sciences in point of method. In the first place it is said--and I take this point first, because the imputation is too frequently admitted by Physiologists themselves--that Biology differs from the Physico-chemical and Mathematical sciences in being "inexact." Now, this phrase "inexact" must refer either to the _methods_ or to the _results_ of Physiological science. It cannot be correct to apply it to the methods; for, as I hope to show you by and by, these are identical in all sciences, and whatever is true of Physiological method is true of Physical and Mathematical method. Is it then the _results_ of Biological science which are "inexact"? I think not. If I say that respiration is performed by the lungs; that digestion is effected in the stomach; that the eye is the organ of sight; that the jaws of a vertebrated animal never open sideways, but always up and down; while those of an annulose animal always open sideways, and never up and down--I am enumerating propositions which are as exact as anything in Euclid. How then has this notion of the inexactness of Biological science come about? I believe from two causes: first, because, in consequence of the great complexity of the science and the multitude of interfering conditions, we are very often only enabled to predict approximatively what will occur under given circumstances; and secondly, because, on account of the comparative youth of the Physiological sciences, a great many of their laws are still imperfectly worked out. But, in an educational point of view, it is most important to distinguish between the essence of a science and the accidents which surround it; and essentially, the methods and results of Physiology are as exact as those of Physics or Mathematics. It is said that the Physiological method is especially _comparative_[4]; and this dictum also finds favour in the eyes of many. I should be sorry to suggest that the speculators on scientific classification have been misled by the accident of the name of one leading branch of Biology--_Comparative Anatomy_; but I would ask whether _comparison_, and that classification which is the result of comparison, are not the essence of every science whatsoever? How is it possible to discover a relation of cause and effect of _any_ kind without comparing a series of cases together in which the supposed cause and effect occur singly, or combined? So far from comparison being in any way peculiar to Biological science, it is, I think, the essence of every science. A speculative philosopher again tells us that the Biological sciences are distinguished by being sciences of observation and not of experiment![5] Of all the strange assertions into which speculation without practical acquaintance with a subject may lead even an able man, I think this is the very strangest. Physiology not an experimental science! Why, there is not a function of a single organ in the body which has not been determined wholly and solely by experiment. How did Harvey determine the nature of the circulation, except by experiment? How did Sir Charles Bell determine the functions of the roots of the spinal nerves, save by experiment? How do we know the use of a nerve at all, except by experiment? Nay, how do you know even that your eye is your seeing apparatus, unless you make the experiment of shutting it; or that your ear is your hearing apparatus, unless you close it up and thereby discover that you become deaf? It would really be much more true to say that Physiology is _the_ experimental science _par excellence_ of all sciences; that in which there is least to be learnt by mere observation, and that which affords the greatest field for the exercise of those faculties which characterise the experimental philosopher. I confess, if any one were to ask me for a model application of the logic of experiment, I should know no better work to put into his hands than Bernard's late Researches on the Functions of the Liver.[6] Not to give this lecture a too controversial tone, however, I must only advert to one more doctrine, held by a thinker of our own age and country, whose opinions are worthy of all respect. It is, that the Biological sciences differ from all others, inasmuch as in _them_ classification takes place by type and not by definition.[7] It is said, in short, that a natural-history class is not capable of being defined--that the class Rosaceæ, for instance, or the class of Fishes, is not accurately and absolutely definable, inasmuch as its members will present exceptions to every possible definition; and that the members of the class are united together only by the circumstance that they are all more like some imaginary average rose or average fish, than they resemble anything else. But here, as before, I think the distinction has arisen entirely from confusing a transitory imperfection with an essential character. So long as our information concerning them is imperfect, we class all objects together according to resemblances which we _feel_, but cannot _define_: we group them round _types_, in short. Thus, if you ask an ordinary person what kinds of animals there are, he will probably say, beasts, birds, reptiles, fishes, insects, &c. Ask him to define a beast from a reptile, and he cannot do it; but he says, things like a cow or a horse are beasts, and things like a frog or a lizard are reptiles. You see _he does_ class by type, and not by definition. But how does this classification differ from that of the scientific Zoologist? How does the meaning of the scientific class-name of "Mammalia" differ from the unscientific of "Beasts"? Why, exactly because the former depends on a definition, the latter on a type. The class Mammalia is scientifically defined as "all animals which have a vertebrated skeleton and suckle their young." Here is no reference to type, but a definition rigorous enough for a geometrician. And such is the character which every scientific naturalist recognises as that to which his classes must aspire--knowing, as he does, that classification by type is simply an acknowledgment of ignorance and a temporary device. So much in the way of negative argument as against the reputed differences, between Biological and other methods. No such differences, I believe, really exist. The subject-matter of Biological science is different from that of other sciences, but the methods of all are identical; and these methods are-- 1. _Observation_ of facts--including under this head that _artificial observation_ which is called _experiment_. 2. That process of tying up similar facts into bundles, ticketed and ready for use, which is called _Comparison_ and _Classification_,--the results of the process, the ticketed bundles, being named _General propositions_. 3. _Deduction_, which takes us from the general proposition to facts again--teaches us, if I may so say, to anticipate from the ticket what is inside the bundle. And finally-- 4. _Verification_, which is the process of ascertaining whether, in point of fact, our anticipation is a correct one. Such are the methods of all science whatsoever; but perhaps you will permit me to give you an illustration of their employment in the science of Life; and I will take as a special case, the establishment of the doctrine of the _Circulation of the Blood_. In this case, _simple observation_ yields us a knowledge of the existence of the blood from some accidental hæmorrhage, we will say: we may even grant that it informs us of the localization of this blood in particular vessels, the heart, &c., from some accidental cut or the like. It teaches also the existence of a pulse in various parts of the body, and acquaints us with the structure of the heart and vessels. Here, however, _simple observation_ stops, and we must have recourse to _experiment_. You tie a vein, and you find that the blood accumulates on the side of the ligature opposite the heart. You tie an artery, and you find that the blood accumulates on the side near the heart. Open the chest, and you see the heart contracting with great force. Make openings into its principal cavities, and you will find that all the blood flows out, and no more pressure is exerted on either side of the arterial or venous ligature. Now all these facts, taken together, constitute the evidence that the blood is propelled by the heart through the arteries, and returns by the veins--that, in short, the blood circulates. Suppose our experiments and observations have been made on horses, then we group and ticket them into a general proposition, thus:--_all horses have a circulation of their blood_. Henceforward a horse is a sort of indication or label, telling us where we shall find a peculiar series of phænomena called the circulation of the blood. Here is our _general proposition_ then. How and when are we justified in making our next step--a _deduction_ from it? Suppose our physiologist, whose experience is limited to horses, meets with a zebra for the first time,--will he suppose that this generalization holds good for zebras also? That depends very much on his turn of mind. But we will suppose him to be a bold man. He will say, "The zebra is certainly not a horse, but it is very like one,--so like, that it must be the 'ticket' or mark of a blood-circulation also; and, I conclude that the zebra has a circulation." That is a deduction, a very fair deduction, but by no means to be considered scientifically secure. This last quality in fact can only be given by _verification_--that is, by making a zebra the subject of all the experiments performed on the horse. Of course, in the present case, the _deduction_ would be _confirmed_ by this process of verification, and the result would be, not merely a positive widening of knowledge, but a fair increase of confidence in the truth of one's generalizations in other cases. Thus, having settled the point in the zebra and horse, our philosopher would have great confidence in the existence of a circulation in the ass. Nay, I fancy most persons would excuse him, if in this case he did not take the trouble to go through the process of verification at all; and it would not be without a parallel in the history of the human mind, if our imaginary physiologist now maintained that he was acquainted with asinine circulation _à priori_. However, if I might impress any caution upon your minds, it is, the utterly conditional nature of all our knowledge,--the danger of neglecting the process of verification under any circumstances; and the film upon which we rest, the moment our deductions carry us beyond the reach of this great process of verification. There is no better instance of this than is afforded by the history of our knowledge of the circulation of the blood in the animal kingdom until the year 1824. In every animal possessing a circulation at all, which had been observed up to that time, the current of the blood was known to take one definite and invariable direction. Now, there is a class of animals called _Ascidians_, which possess a heart and a circulation, and up to the period of which I speak, no one would have dreamt of questioning the propriety of the deduction, that these creatures have a circulation in one direction; nor would any one have thought it worth while to verify the point. But, in that year, M. von Hasselt happening to examine a transparent animal of this class, found to his infinite surprise, that after the heart had beat a certain number of times, it stopped, and then began beating the opposite way--so as to reverse the course of the current, which returned by and by to its original direction. I have myself timed the heart of these little animals. I found it as regular as possible in its periods of reversal: and I know no spectacle in the animal kingdom more wonderful than that which it presents--all the more wonderful that to this day it remains an unique fact, peculiar to this class among the whole animated world. At the same time I know of no more striking case of the necessity of the _verification_ of even those deductions which seem founded on the widest and safest inductions. Such are the methods of Biology--methods which are obviously identical with those of all other sciences, and therefore wholly incompetent to form the ground of any distinction between it and them.[8] But I shall be asked at once, Do you mean to say that there is no difference between the habit of mind of a mathematician and that of a naturalist? Do you imagine that Laplace might have been put into the Jardin des Plantes, and Cuvier into the Observatory, with equal advantage to the progress of the sciences they professed? To which I would reply, that nothing could be further from my thoughts. But different habits and various special tendencies of two sciences do not imply different methods. The mountaineer and the man of the plains have very different habits of progression, and each would be at a loss in the other's place; but the method of progression, by putting one leg before the other, is the same in each case. Every step of each is a combination of a lift and a push; but the mountaineer lifts more and the lowlander pushes more. And I think the case of two sciences resembles this. I do not question for a moment, that while the Mathematician is busied with deductions _from_ general propositions, the Biologist is more especially occupied with observation, comparison, and those processes which lead _to_ general propositions. All I wish to insist upon is, that this difference depends not on any fundamental distinction in the sciences themselves, but on the accidents of their subject-matter, of their relative complexity, and consequent relative perfection. The Mathematician deals with two properties of objects only, number and extension, and all the inductions he wants have been formed and finished ages ago. He is occupied now with nothing but deduction and verification. The Biologist deals with a vast number of properties of objects, and his inductions will not be completed, I fear, for ages to come; but when they are, his science will be as deductive and as exact as the Mathematics themselves. Such is the relation of Biology to those sciences which deal with objects having fewer properties than itself. But as the student, in reaching Biology, looks back upon sciences of a less complex and therefore more perfect nature; so, on the other hand, does he look forward to other more complex and less perfect branches of knowledge. Biology deals only with living beings as isolated things--treats only of the life of the individual: but there is a higher division of science still, which considers living beings as aggregates--which deals with the relation of living beings one to another--the science which _observes_ men--whose _experiments_ are made by nations one upon another, in battle-fields--whose _general propositions_ are embodied in history, morality, and religion--whose _deductions_ lead to our happiness or our misery,--and whose _verifications_ so often come too late, and serve only "To point a moral or adorn a tale"-- I mean the science of Society or _Sociology_. I think it is one of the grandest features of Biology, that it occupies this central position in human knowledge. There is no side of the human mind which physiological study leaves uncultivated. Connected by innumerable ties with abstract science, Physiology is yet in the most intimate relation with humanity; and by teaching us that law and order, and a definite scheme of development, regulate even the strangest and wildest manifestations of individual life, she prepares the student to look for a goal even amidst the erratic wanderings of mankind, and to believe that history offers something more than an entertaining chaos--a journal of a toilsome, tragi-comic march nowhither. The preceding considerations have, I hope, served to indicate the replies which befit the two first of the questions which I set before you at starting, viz. what is the range and position of Physiological Science as a branch of knowledge, and what is its value as a means of mental discipline. Its _subject-matter_ is a large moiety of the universe--its _position_ is midway between the physico-chemical and the social sciences. Its _value_ as a branch of discipline is partly that which it has in common with all sciences--the training and strengthening of common sense; partly that which is more peculiar to itself--the great exercise which it affords to the faculties of observation and comparison; and I may add, the _exactness_ of knowledge which it requires on the part of those among its votaries who desire to extend its boundaries. If what has been said as to the position and scope of Biology be correct, our third question--What is the practical value of physiological instruction?--might, one would think, be left to answer itself. On other grounds even, were mankind deserving of the title "rational," which they arrogate to themselves, there can be no question that they would consider, as the most necessary of all branches of instruction for themselves and for their children, that which professes to acquaint them with the conditions of the existence they prize so highly--which teaches them how to avoid disease and to cherish health, in themselves and those who are dear to them. I am addressing, I imagine, an audience of educated persons; and yet I dare venture to assert that, with the exception of those of my hearers who may chance to have received a medical education, there is not one who could tell me what is the meaning and use of an act which he performs a score of times every minute, and whose suspension would involve his immediate death;--I mean the act of breathing--or who could state in precise terms why it is that a confined atmosphere is injurious to health. The _practical value_ of Physiological knowledge! Why is it that educated men can be found to maintain that a slaughter-house in the midst of a great city is rather a good thing than otherwise?--that mothers persist in exposing the largest possible amount of surface of their children to the cold, by the absurd style of dress they adopt, and then marvel at the peculiar dispensation of Providence, which removes their infants by bronchitis and gastric fever? Why is it that quackery rides rampant over the land; and that not long ago, one of the largest public rooms in this great city could be filled by an audience gravely listening to the reverend expositor of the doctrine--that the simple physiological phenomena known as spirit-rapping, table-turning, phreno-magnetism, and by I know not what other absurd and inappropriate names, are due to the direct and personal agency of Satan? Why is all this, except from the utter ignorance as to the simplest laws of their own animal life, which prevails among even the most highly educated persons in this country? But there are other branches of Biological Science, besides Physiology proper, whose practical influence, though less obvious, is not, as I believe, less certain. I have heard educated men speak with an ill-disguised contempt of the studies of the naturalist, and ask, not without a shrug, "What is the use of knowing all about these miserable animals--what bearing has it on human life?" I will endeavour to answer that question. I take it that all will admit there is definite Government of this universe--that its pleasures and pains are not scattered at random, but are distributed in accordance with orderly and fixed laws, and that it is only in accordance with all we know of the rest of the world, that there should be an agreement between one portion of the sensitive creation and another in these matters. Surely then it interests us to know the lot of other animal creatures--however far below us, they are still the sole created things which share with us the capability of pleasure and the susceptibility to pain. I cannot but think that he who finds a certain proportion of pain and evil inseparably woven up in the life of the very worms, will bear his own share with more courage and submission; and will, at any rate, view with suspicion those weakly amiable theories of the Divine government, which would have us believe pain to be an oversight and a mistake,--to be corrected by and by. On the other hand, the predominance of happiness among living things--their lavish beauty--the secret and wonderful harmony which pervades them all, from the highest to the lowest, are equally striking refutations of that modern Manichean doctrine, which exhibits the world as a slave-mill, worked with many tears, for mere utilitarian ends. There is yet another way in which natural history may, I am convinced, take a profound hold upon practical life,--and that is, by its influence over our finer feelings, as the greatest of all sources of that pleasure which is derivable from beauty. I do not pretend that natural-history knowledge, as such, can increase our sense of the beautiful in natural objects. I do not suppose that the dead soul of Peter Bell, of whom the great poet of nature says,-- A primrose by the river's brim, A yellow primrose was to him,-- And it was nothing more,-- would have been a whit roused from its apathy, by the information that the primrose is a Dicotyledonous Exogen, with a monopetalous corolla and central placentation. But I advocate natural-history knowledge from this point of view, because it would lead us to _seek_ the beauties of natural objects, instead of trusting to chance to force them on our attention. To a person uninstructed in natural history, his country, or sea-side, stroll is a walk through a gallery filled with wonderful works of art, nine-tenths of which have their faces turned to the wall. Teach him something of natural history, and you place in his hands a catalogue of those which are worth turning round. Surely our innocent pleasures are not so abundant in this life, that we can afford to despise this or any other source of them. We should fear being banished for our neglect to that limbo, where the great Florentine tells us are those who, during this life, "wept when they might be joyful." But I shall be trespassing unwarrantably on your kindness, if I do not proceed at once to my last point--the time at which Physiological Science should first form a part of the Curriculum of Education. The distinction between the teaching of the facts of a science as instruction, and the teaching it systematically as knowledge, has already been placed before you in a previous lecture: and it appears to me, that, as with other sciences, the _common facts_ of Biology--the uses of parts of the body--the names and habits of the living creatures which surround us--may be taught with advantage to the youngest child. Indeed, the avidity of children for this kind of knowledge, and the comparative ease with which they retain it, is something quite marvellous. I doubt whether any toy would be so acceptable to young children as a vivarium, of the same kind as, but of course on a smaller scale than, those admirable devices in the Zoological Gardens. On the other hand, systematic teaching in Biology cannot be attempted with success until the student has attained to a certain knowledge of physics and chemistry: for though the phænomena of life are dependent neither on physical nor on chemical, but on vital forces, yet they result in all sorts of physical and chemical changes, which can only be judged by their own laws. And now to sum up in a few words the conclusions to which I hope you see reason to follow me. Biology needs no apologist when she demands a place--and a prominent place--in any scheme of education worthy of the name. Leave out the Physiological sciences from your curriculum, and you launch the student into the world, undisciplined in that science whose subject-matter would best develop his powers of observation; ignorant of facts of the deepest importance for his own and others' welfare; blind to the richest sources of beauty in God's creation; and unprovided with that belief in a living law, and an order manifesting itself in and through endless change and variety, which might serve to check and moderate that phase of despair through which, if he take an earnest interest in social problems, he will assuredly sooner or later pass. Finally, one word for myself. I have not hesitated to speak strongly where I have felt strongly; and I am but too conscious that the indicative and imperative moods have too often taken the place of the more becoming subjunctive and conditional. I feel, therefore, how necessary it is to beg you to forget the personality of him who has thus ventured to address you, and to consider only the truth or error in what has been said. FOOTNOTES: [4] "In the third place, we have to review the method of Comparison, which is so specially adapted to the study of living bodies, and by which, above all others, that study must be advanced. In Astronomy, this method is necessarily inapplicable; and it is not till we arrive at Chemistry that this third means of investigation can be used, and then only in subordination to the two others. It is in the study, both statical and dynamical, of living bodies that it first acquires its full development; and its use elsewhere can be only through its application here."--COMTE'S _Positive Philosophy_, translated by Miss Martineau. Vol. i. p. 372. By what method does M. Comte suppose that the equality or inequality of forces and quantities and the dissimilarity or similarity of forms--points of some slight importance not only in Astronomy and Physics, but even in Mathematics--are ascertained, if not by Comparison? [5] "Proceeding to the second class of means,--Experiment cannot but be less and less decisive, in proportion to the complexity of the phænomena to be explored; and therefore we saw this resource to be less effectual in chemistry than in physics: and we now find that it is eminently useful in chemistry in comparison with physiology. _In fact, the nature of the phænomena seems to offer almost insurmountable impediments to any extensive and prolific application of such a procedure in biology._"--Comte, vol i. p. 367. M. Comte, as his manner is, contradicts himself two pages further on, but that will hardly relieve him from the responsibility of such a paragraph as the above. [6] "Nouvelle Fonction du Foie considéré comme organe producteur de matière sucrée chez l'Homme et les Animaux," par M. Claude Bernard. [7] "_Natural Groups given by Type, not by Definition...._ The class is steadily fixed, though not precisely limited; it is given, though not circumscribed; it is determined, not by a boundary-line without, but by a central point within; not by what it strictly excludes, but what it eminently includes; by an example, not by a precept; in short, instead of Definition we have a _Type_ for our director. A type is an example of any class, for instance, a species of a genus, which is considered as eminently possessing the characters of the class. All the species which have a greater affinity with this type-species than with any others, form the genus, and are ranged about it, deviating from it in various directions and different degrees."--WHEWELL, _The Philosophy of the Inductive Sciences_, vol. i. pp. 476, 477. [8] Save for the pleasure of doing so, I need hardly point out my obligations to Mr. J.S. Mill's "System of Logic," in this view of scientific method. VI. ON THE STUDY OF ZOOLOGY. Natural history is the name familiarly applied to the study of the properties of such natural bodies as minerals, plants, and animals; the sciences which embody the knowledge man has acquired upon these subjects are commonly termed Natural Sciences, in contradistinction to other, so-called "physical," sciences; and those who devote themselves especially to the pursuit of such sciences have been, and are, commonly termed "Naturalists." Linnæus was a naturalist in this wide sense, and his "Systema Naturæ" was a work upon natural history, in the broadest acceptation of the term; in it, that great methodizing spirit embodied all that was known in his time of the distinctive characters of minerals, animals, and plants. But the enormous stimulus which Linnæus gave to the investigation of nature soon rendered it impossible that any one man should write another "Systema Naturæ," and extremely difficult for any one to become a naturalist such as Linnæus was. Great as have been the advances made by all the three branches of science, of old included under the title of natural history, there can be no doubt that zoology and botany have grown in an enormously greater ratio than mineralogy; and hence, as I suppose, the name of "natural history" has gradually become more and more definitely attached to these prominent divisions of the subject, and by "naturalist" people have meant more and more distinctly to imply a student of the structure and functions of living beings. However this may be, it is certain that the advance of knowledge has gradually widened the distance between mineralogy and its old associates, while it has drawn zoology and botany closer together; so that of late years it has been found convenient (and indeed necessary) to associate the sciences which deal with vitality and all its phenomena under the common head of "biology;" and the biologists have come to repudiate any blood-relationship with their foster-brothers, the mineralogists. Certain broad laws have a general application throughout both the animal and the vegetable worlds, but the ground common to these kingdoms of nature is not of very wide extent, and the multiplicity of details is so great, that the student of living beings finds himself obliged to devote his attention exclusively either to the one or the other. If he elects to study plants, under any aspect, we know at once what to call him; he is a botanist, and his science is botany. But if the investigation of animal life be his choice, the name generally applied to him will vary, according to the kind of animals he studies, or the particular phenomena of animal life to which he confines his attention. If the study of man is his object, he is called an anatomist, or a physiologist, or an ethnologist; but if he dissects animals, or examines into the mode in which their functions are performed, he is a comparative anatomist or comparative physiologist. If he turns his attention to fossil animals, he is a palæontologist. If his mind is more particularly directed to the description, specific discrimination, classification, and distribution of animals, he is termed a zoologist. For the purposes of the present discourse, however, I shall recognise none of these titles save the last, which I shall employ as the equivalent of botanist, and I shall use the term zoology as denoting the whole doctrine of animal life, in contradistinction to botany, which signifies the whole doctrine of vegetable life. Employed in this sense, zoology, like botany, is divisible into three great but subordinate sciences, morphology, physiology, and distribution, each of which may, to a very great extent, be studied independently of the other. Zoological morphology is the doctrine of animal form or structure. Anatomy is one of its branches, development is another; while classification is the expression of the relations which different animals bear to one another, in respect of their anatomy and their development. Zoological distribution is the study of animals in relation to the terrestrial conditions which obtain now, or have obtained at any previous epoch of the earth's history. Zoological physiology, lastly, is the doctrine of the functions or actions of animals. It regards animal bodies as machines impelled by certain forces, and performing an amount of work, which can be expressed in terms of the ordinary forces of nature. The final object of physiology is to deduce the facts of morphology, on the one hand, and those of distribution on the other, from the laws of the molecular forces of matter. Such is the scope of zoology. But if I were to content myself with the enunciation of these dry definitions, I should ill exemplify that method of teaching this branch of physical science, which it is my chief business to-night to recommend. Let us turn away then from abstract definitions. Let us take some concrete living thing, some animal, the commoner the better, and let us see how the application of common sense and common logic to the obvious facts it presents, inevitably leads us into all these branches of zoological science. I have before me a lobster. When I examine it, what appears to be the most striking character it presents? Why, I observe that this part which we call the tail of the lobster, is made up of six distinct hard rings and a seventh terminal piece. If I separate one of the middle rings, say the third, I find it carries upon its under surface a pair of limbs or appendages, each of which consists of a stalk and two terminal pieces. So that I can represent a transverse section of the ring and its appendages upon the diagram board in this way. If I now take the fourth ring I find it has the same structure, and so have the fifth and the second; so that, in each of these divisions of the tail, I find parts which correspond with one another, a ring and two appendages; and in each appendage a stalk and two end pieces. These corresponding parts are called, in the technical language of anatomy, "homologous parts." The ring of the third division is the "homologue" of the ring of the fifth, the appendage of the former is the homologue of the appendage of the latter. And, as each division exhibits corresponding parts in corresponding places, we say that all the divisions are constructed upon the same plan. But now let us consider the sixth division. It is similar to, and yet different from, the others. The ring is essentially the same as in the other divisions; but the appendages look at first as if they were very different; and yet when we regard them closely, what do we find? A stalk and two terminal divisions, exactly as in the others, but the stalk is very short and very thick, the terminal divisions are very broad and flat, and one of them is divided into two pieces. I may say, therefore, that the sixth segment is like the others in plan, but that it is modified in its details. The first segment is like the others, so far as its ring is concerned, and though its appendages differ from any of those yet examined in the simplicity of their structure, parts corresponding with the stem and one of the divisions of the appendages of the other segments can be readily discerned in them. Thus it appears that the lobster's tail is composed of a series of segments which are fundamentally similar, though each presents peculiar modifications of the plan common to all. But when I turn to the fore part of the body I see, at first, nothing but a great shield-like shell, called technically the "carapace," ending in front in a sharp spine, on either side of which are the curious compound eyes, set upon the ends of stout moveable stalks. Behind these, on the under side of the body, are two pairs of long feelers, or antennæ, followed by six pairs of jaws, folded against one another over the mouth, and five pairs of legs, the foremost of these being the great pinchers, or claws, of the lobster. It looks, at first, a little hopeless to attempt to find in this complex mass a series of rings, each with its pair of appendages, such as I have shown you in the abdomen, and yet it is not difficult to demonstrate their existence. Strip off the legs, and you will find that each pair is attached to a very definite segment of the under wall of the body; but these segments, instead of being the lower parts of free rings, as in the tail, are such parts of rings which are all solidly united and bound together; and the like is true of the jaws, the feelers, and the eye-stalks, every pair of which is borne upon its own special segment. Thus the conclusion is gradually forced upon us, that the body of the lobster is composed of as many rings as there are pairs of appendages, namely, twenty in all, but that the six hindmost rings remain free and moveable, while the fourteen front rings become firmly soldered together, their backs forming one continuous shield--the carapace. Unity of plan, diversity in execution, is the lesson taught by the study of the rings of the body, and the same instruction is given still more emphatically by the appendages. If I examine the outermost jaw I find it consists of three distinct portions, an inner, a middle, and an outer, mounted upon a common stem; and if I compare this jaw with the legs behind it, or the jaws in front of it, I find it quite easy to see, that, in the legs, it is the part of the appendage which corresponds with the inner division, which becomes modified into what we know familiarly as the "leg," while the middle division, disappears, and the outer division is hidden under the carapace. Nor is it more difficult to discern that, in the appendages of the tail, the middle division appears again and the outer vanishes; while, on the other hand, in the foremost jaw, the so-called mandible, the inner division only is left; and, in the same way, the parts of the feelers and of the eye-stalks can be identified with those of the legs and jaws. But whither does all this tend? To the very remarkable conclusion that a unity of plan, of the same kind as that discoverable in the tail or abdomen of the lobster, pervades the whole organization of its skeleton, so that I can return to the diagram representing any one of the rings of the tail, which I drew upon the board, and by adding a third division to each appendage, I can use it as a sort of scheme or plan of any ring of the body. I can give names to all the parts of that figure, and then if I take any segment of the body of the lobster, I can point out to you exactly, what modification the general plan has undergone in that particular segment; what part has remained moveable, and what has become fixed to another; what has been excessively developed and metamorphosed, and what has been suppressed. But I imagine I hear the question, How is all this to be tested? No doubt it is a pretty and ingenious way of looking at the structure of any animal, but is it anything more? Does Nature acknowledge, in any deeper way, this unity of plan we seem to trace? The objection suggested by these questions is a very valid and important one, and morphology was in an unsound state, so long as it rested upon the mere perception of the analogies which obtain between fully formed parts. The unchecked ingenuity of speculative anatomists proved itself fully competent to spin any number of contradictory hypotheses out of the same facts, and endless morphological dreams threatened to supplant scientific theory. Happily, however, there is a criterion of morphological truth, and a sure test of all homologies. Our lobster has not always been what we see it; it was once an egg, a semifluid mass of yolk, not so big as a pin's head, contained in a transparent membrane, and exhibiting not the least trace of any one of those organs, whose multiplicity and complexity, in the adult, are so surprising. After a time a delicate patch of cellular membrane appeared upon one face of this yolk, and that patch was the foundation of the whole creature, the clay out of which it would be moulded. Gradually investing the yolk, it became subdivided by transverse constrictions into segments, the forerunners of the rings of the body. Upon the ventral surface of each of the rings thus sketched out, a pair of bud-like prominences made their appearance--the rudiments of the appendages of the ring. At first, all the appendages were alike, but, as they grew, most of them became distinguished into a stem and two terminal divisions, to which, in the middle part of the body, was added a third outer division; and it was only at a later period, that by the modification, or absorption, of certain of these primitive constituents, the limbs acquired their perfect form. Thus the study of development proves that the doctrine of unity of plan is not merely a fancy, that it is not merely one way of looking at the matter, but that it is the expression of deep-seated natural facts. The legs and jaws of the lobster may not merely be regarded as modifications of a common type,--in fact and in nature they are so,--the leg and the jaw of the young animal being, at first, indistinguishable. These are wonderful truths, the more so because the zoologist finds them to be of universal application. The investigation of a polype, of a snail, of a fish, of a horse, or of a man, would have led us, though by a less easy path, perhaps, to exactly the same point. Unity of plan everywhere lies hidden under the mask of diversity of structure--the complex is everywhere evolved out of the simple. Every animal has at first the form of an egg, and every animal and every organic part, in reaching its adult state, passes through conditions common to other animals and other adult parts; and this leads me to another point. I have hitherto spoken as if the lobster were alone in the world, but, as I need hardly remind you, there are myriads of other animal organisms. Of these, some, such as men, horses, birds, fishes, snails, slugs, oysters, corals, and sponges, are not in the least like the lobster. But other animals, though they may differ a good deal from the lobster, are yet either very like it, or are like something that is like it. The cray fish, the rock lobster, and the prawn, and the shrimp, for example, however different, are yet so like lobsters, that a child would group them as of the lobster kind, in contradistinction to snails and slugs; and these last again would form a kind by themselves, in contradistinction to cows, horses, and sheep, the cattle kind. But this spontaneous grouping into "kinds" is the first essay of the human mind at classification, or the calling by a common name of those things that are alike, and the arranging them in such a manner as best to suggest the sum of their likenesses and unlikenesses to other things. Those kinds which include no other subdivisions than the sexes, or various breeds, are called, in technical language, species. The English lobster is a species, our cray fish is another, our prawn is another. In other countries, however, there are lobsters, cray fish, and prawns, very like ours, and yet presenting sufficient differences to deserve distinction. Naturalists, therefore, express this resemblance and this diversity by grouping them as distinct species of the same "genus." But the lobster and the cray fish, though belonging to distinct genera, have many features in common, and hence are grouped together in an assemblage which is called a family. More distant resemblances connect the lobster with the prawn and the crab, which are expressed by putting all these into the same order. Again, more remote, but still very definite, resemblances unite the lobster with the woodlouse, the king crab, the water-flea, and the barnacle, and separate them from all other animals; whence they collectively constitute the larger group, or class, _Crustacea_. But the _Crustacea_ exhibit many peculiar features in common with insects, spiders, and centipedes, so that these are grouped into the still larger assemblage or "province" _Articulata_; and, finally, the relations which these have to worms and other lower animals, are expressed by combining the whole vast aggregate into the sub-kingdom of _Annulosa_. If I had worked my way from a sponge instead of a lobster, I should have found it associated, by like ties, with a great number of other animals into the sub-kingdom _Protozoa_; if I had selected a fresh-water polype or a coral, the members of what naturalists term the sub-kingdom _C�lenterata_ would have grouped themselves around my type; had a snail been chosen, the inhabitants of all univalve and bivalve, land and water, shells, the lamp shells, the squids, and the sea-mat would have gradually linked themselves on to it as members of the same sub-kingdom of _Mollusca_; and finally, starting from man, I should have been compelled to admit first, the ape, the rat, the horse, the dog, into the same class; and then the bird, the crocodile, the turtle, the frog, and the fish, into the same sub-kingdom of _Vertebrata_. And if I had followed out all these various lines of classification fully, I should discover in the end that there was no animal, either recent or fossil, which did not at once fall into one or other of these sub-kingdoms. In other words, every animal is organized upon one or other of the five, or more, plans, whose existence renders our classification possible. And so definitely and precisely marked is the structure of each animal, that, in the present state of our knowledge, there is not the least evidence to prove that a form, in the slightest degree transitional between any of the two groups _Vertebrata, Annulosa, Mollusca_, and _C�lenterata_, either exists, or has existed, during that period of the earth's history which is recorded by the geologist. Nevertheless, you must not for a moment suppose, because no such transitional forms are known, that the members of the sub-kingdoms are disconnected from, or independent of, one another. On the contrary, in their earliest condition they are all alike, and the primordial germs of a man, a dog, a bird, a fish, a beetle, a snail, and a polype are, in no essential structural respects, distinguishable. In this broad sense, it may with truth be said, that all living animals, and all those dead creations which geology reveals, are bound together by an all-pervading unity of organization, of the same character, though not equal in degree, to that which enables us to discern one and the same plan amidst the twenty different segments of a lobster's body. Truly it has been said, that to a clear eye the smallest fact is a window through which the Infinite may be seen. Turning from these purely morphological considerations, let us now examine into the manner in which the attentive study of the lobster impels us into other lines of research. Lobsters are found in all the European seas; but on the opposite shores of the Atlantic and in the seas of the southern hemisphere they do not exist. They are, however, represented in these regions by very closely allied, but distinct forms--the _Homarus Americanus_ and the _Homarus Capensis_: so that we may say that the European has one species of _Homarus_; the American, another; the African, another; and thus the remarkable facts of geographical distribution begin to dawn upon us. Again, if we examine the contents of the earth's crust, we shall find in the latter of those deposits, which have served as the great burying grounds of past ages, numberless lobster-like animals, but none so similar to our living lobster as to make zoologists sure that they belonged even to the same genus. If we go still further back in time, we discover, in the oldest rocks of all, the remains of animals, constructed on the same general plan as the lobster, and belonging to the same great group of _Crustacea_; but for the most part totally different from the lobster, and indeed from any other living form of crustacean; and thus we gain a notion of that successive change of the animal population of the globe, in past ages, which is the most striking fact revealed by geology. Consider, now, where our inquiries have led us. We studied our type morphologically, when we determined its anatomy and its development, and when comparing it, in these respects, with other animals, we made out its place in a system of classification. If we were to examine every animal in a similar manner, we should establish a complete body of zoological morphology. Again, we investigated the distribution of our type in space and in time, and, if the like had been done with every animal, the sciences of geographical and geological distribution would have attained their limit. But you will observe one remarkable circumstance, that, up to this point, the question of the life of these organisms has not come under consideration. Morphology and distribution might be studied almost as well, if animals and plants were a peculiar kind of crystals, and possessed none of those functions which distinguish living beings so remarkably. But the facts of morphology and distribution have to be accounted for, and the science, whose aim it is to account for them, is Physiology. Let us return to our lobster once more. If we watched the creature in its native element, we should see it climbing actively the submerged rocks, among which it delights to live, by means of its strong legs; or swimming by powerful strokes of its great tail, the appendages of whose sixth joint are spread out into a broad fan-like propeller: seize it, and it will show you that its great claws are no mean weapons of offence; suspend a piece of carrion among its haunts, and it will greedily devour it, tearing and crushing the flesh by means of its multitudinous jaws. Suppose that we had known nothing of the lobster but as an inert mass, an organic crystal, if I may use the phrase, and that we could suddenly see it exerting all these powers, what wonderful new ideas and new questions would arise in our minds! The great new question would be, "How does all this take place?" the chief new idea would be, the idea of adaptation to purpose,--the notion, that the constituents of animal bodies are not mere unconnected parts, but organs working together to an end. Let us consider the tail of the lobster again from this point of view. Morphology has taught us that it is a series of segments composed of homologous parts, which undergo various modifications--beneath and through which a common plan of formation is discernible. But if I look at the same part physiologically, I see that it is a most beautifully constructed organ of locomotion, by means of which the animal can swiftly propel itself either backwards or forwards. But how is this remarkable propulsive machine made to perform its functions? If I were suddenly to kill one of these animals and to take out all the soft parts, I should find the shell to be perfectly inert, to have no more power of moving itself than is possessed by the machinery of a mill, when disconnected from its steam-engine or water-wheel. But if I were to open it, and take out the viscera only, leaving the white flesh, I should perceive that the lobster could bend and extend its tail as well as before. If I were to cut off the tail, I should cease to find any spontaneous motion in it; but on pinching any portion of the flesh, I should observe that it underwent a very curious change--each fibre becoming shorter and thicker. By this act of contraction, as it is termed, the parts to which the ends of the fibre are attached are, of course, approximated; and according to the relations of their points of attachment to the centres of motion of the different rings, the bending or the extension of the tail results. Close observation of the newly opened lobster would soon show that all its movements are due to the same cause--the shortening and thickening of these fleshy fibres, which are technically called muscles. Here, then, is a capital fact. The movements of the lobster are due to muscular contractility. But why does a muscle contract at one time and not at another? Why does one whole group of muscles contract when the lobster wishes to extend his tail, and another group, when he desires to bend it? What is it originates, directs, and controls the motive power? Experiment, the great instrument for the ascertainment of truth in physical science, answers this question for us. In the head of the lobster there lies a small mass of that peculiar tissue which is known as nervous substance. Cords of similar matter connect this brain of the lobster, directly or indirectly, with the muscles. Now, if these communicating cords are cut, the brain remaining entire, the power of exerting what we call voluntary motion in the parts below the section is destroyed; and on the other hand, if, the cords remaining entire, the brain mass be destroyed, the same voluntary mobility is equally lost. Whence the inevitable conclusion is, that the power of originating these motions resides in the brain, and is propagated along the nervous cords. In the higher animals the phænomena which attend this transmission have been investigated, and the exertion of the peculiar energy which resides in the nerves has been found to be accompanied by a disturbance of the electrical state of their molecules. If we could exactly estimate the signification of this disturbance; if we could obtain the value of a given exertion of nerve force by determining the quantity of electricity, or of heat, of which it is the equivalent; if we could ascertain upon what arrangement, or other condition of the molecules of matter, the manifestation of the nervous and muscular energies depends, (and doubtless science will some day or other ascertain these points,) physiologists would have attained their ultimate goal in this direction; they would have determined the relation of the motive force of animals to the other forms of force found in nature; and if the same process had been successfully performed for all the operations which are carried on in, and by, the animal frame, physiology would be perfect, and the facts of morphology and distribution would be deducible from the laws which physiologists had established, combined with those determining the condition of the surrounding universe. There is not a fragment of the organism of this humble animal, whose study would not lead us into regions of thought as large as those which I have briefly opened up to you; but what I have been saying, I trust, has not only enabled you to form a conception of the scope and purport of zoology, but has given you an imperfect example of the manner in which, in my opinion, that science, or indeed any physical science, may be best taught. The great matter is, to make teaching real and practical, by fixing the attention of the student on particular facts; but at the same time it should be rendered broad and comprehensive, by constant reference to the generalizations of which all particular facts are illustrations. The lobster has served as a type of the whole animal kingdom, and its anatomy and physiology have illustrated for us some of the greatest truths of biology. The student who has once seen for himself the facts which I have described, has had their relations explained to him, and has clearly comprehended them, has, so far, a knowledge of zoology, which is real and genuine, however limited it may be, and which is worth more than all the mere reading knowledge of the science he could ever acquire. His zoological information is, so far, knowledge and not mere hearsay. And if it were my business to fit you for the certificate in zoological science granted by this department, I should pursue a course precisely similar in principle to that which I have taken to-night. I should select a fresh-water sponge, a fresh-water polype or a _Cyanæa_, a fresh-water mussel, a lobster, a fowl, as types of the five primary divisions of the animal kingdom. I should explain their structure very fully, and show how each illustrated the great principles of zoology. Having gone very carefully and fully over this ground, I should feel that you had a safe foundation, and I should then take you in the same way, but less minutely, over similarly selected illustrative types of the classes; and then I should direct your attention to the special forms enumerated under the head of types, in this syllabus, and to the other facts there mentioned. That would, speaking generally, be my plan. But I have undertaken to explain to you the best mode of acquiring and communicating a knowledge of zoology, and you may therefore fairly ask me for a more detailed and precise account of the manner in which I should propose to furnish you with the information I refer to. My own impression is, that the best model for all kinds of training in physical science is that afforded by the method of teaching anatomy, in use in the medical schools. This method consists of three elements--lectures, demonstrations, and examinations. The object of lectures is, in the first place, to awaken the attention and excite the enthusiasm of the student; and this, I am sure, may be effected to a far greater extent by the oral discourse and by the personal influence of a respected teacher than in any other way. Secondly, lectures have the double use of guiding the student to the salient points of a subject, and at the same time forcing him to attend to the whole of it, and not merely to that part which takes his fancy. And lastly, lectures afford the student the opportunity of seeking explanations of those difficulties which will; and indeed ought to, arise in the course of his studies. But for a student to derive the utmost possible value from lectures, several precautions are needful. I have a strong impression that the better a discourse is, as an oration, the worse it is as a lecture. The flow of the discourse carries you on without proper attention to its sense; you drop a word or a phrase, you lose the exact meaning for a moment, and while you strive to recover yourself, the speaker has passed on to something else. The practice I have adopted of late years, in lecturing to students, is to condense the substance of the hour's discourse into a few dry propositions, which are read slowly and taken down from dictation; the reading of each being followed by a free commentary, expanding and illustrating the proposition, explaining terms, and removing any difficulties that may be attackable in that way, by diagrams made roughly, and seen to grow under the lecturer's hand. In this manner you, at any rate, insure the co-operation of the student to a certain extent. He cannot leave the lecture-room entirely empty if the taking of notes is enforced; and a student must be preternaturally dull and mechanical, if he can take notes and hear them properly explained, and yet learn nothing. What books shall I read? is a question constantly put by the student to the teacher. My reply usually is, "None: write your notes out carefully and fully; strive to understand them thoroughly; come to me for the explanation of anything you cannot understand; and I would rather you did not distract your mind by reading." A properly composed course of lectures ought to contain fully as much matter as a student can assimilate in the time occupied by its delivery; and the teacher should always recollect that his business is to feed, and not to cram the intellect. Indeed, I believe that a student who gains from a course of lectures the simple habit of concentrating his attention upon a definitely limited series of facts, until they are thoroughly mastered, has made a step of immeasurable importance. But, however good lectures may be, and however extensive the course of reading by which they are followed up, they are but accessories to the great instrument of scientific teaching--demonstration. If I insist unweariedly, nay fanatically, upon the importance of physical science as an educational agent, it is because the study of any branch of science, if properly conducted, appears to me to fill up a void left by all other means of education. I have the greatest respect and love for literature; nothing would grieve me more than to see literary training other than a very prominent branch of education: indeed, I wish that real literary discipline were far more attended to than it is; but I cannot shut my eyes to the fact, that there is a vast difference between men who have had a purely literary, and those who have had a sound scientific, training. Seeking for the cause of this difference, I imagine I can find it in the fact, that, in the world of letters, learning and knowledge are one, and books are the source of both; whereas in science, as in life, learning and knowledge are distinct, and the study of things, and not of books, is the source of the latter. All that literature has to bestow may be obtained by reading and by practical exercise in writing, and in speaking; but I do not exaggerate when I say, that none of the best gifts of science are to be won by these means. On the contrary, the great benefit which a scientific education bestows, whether as training or as knowledge, is dependent upon the extent to which the mind of the student is brought into immediate contact with facts--upon the degree to which he learns the habit of appealing directly to Nature, and of acquiring through his senses concrete images of those properties of things, which are, and always will be, but approximatively expressed in human language. Our way of looking at Nature, and of speaking about her, varies from year to year; but a fact once seen, a relation of cause and effect, once demonstratively apprehended, are possessions which neither change nor pass away, but, on the contrary, form fixed centres, about which other truths aggregate by natural affinity. Therefore, the great business of the scientific teacher is, to imprint the fundamental, irrefragable facts of his science, not only by words upon the mind, but by sensible impressions upon the eye, and ear, and touch of the student, in so complete a manner, that every term used, or law enunciated, should afterwards call up vivid images of the particular structural, or other, facts which furnished the demonstration of the law, or the illustration of the term. Now this important operation can only be achieved by constant demonstration, which may take place to a certain imperfect extent during a lecture, but which ought also to be carried on independently, and which should be addressed to each individual student, the teacher endeavouring, not so much to show a thing to the learner, as to make him see it for himself. I am well aware that there are great practical difficulties in the way of effectual zoological demonstrations. The dissection of animals is not altogether pleasant, and requires much time; nor is it easy to secure an adequate supply of the needful specimens. The botanist has here a great advantage; his specimens are easily obtained, are clean and wholesome, and can be dissected in a private house as well as anywhere else; and hence, I believe, the fact, that botany is so much more readily and better taught than its sister science. But, be it difficult or be it easy, if zoological science is to be properly studied, demonstration, and, consequently, dissection, must be had. Without it, no man can have a really sound knowledge of animal organization. A good deal may be done, however, without actual dissection on the student's part, by demonstration upon specimens and preparations; and in all probability it would not be very difficult, were the demand sufficient, to organize collections of such objects, sufficient for all the purposes of elementary teaching, at a comparatively cheap rate. Even without these, much might be effected, if the zoological collections, which are open to the public, were arranged according to what has been termed the "typical principle;" that is to say, if the specimens exposed to public view were so selected, that the public could learn something from them, instead of being, as at present, merely confused by their multiplicity. For example, the grand ornithological gallery at the British Museum contains between two and three thousand species of birds, and sometimes five or six specimens of a species. They are very pretty to look at, and some of the cases are, indeed, splendid; but undertake to say, that no man but a professed ornithologist has ever gathered much information from the collection. Certainly, no one of the tens of thousands of the general public who have walked through that gallery ever knew more about the essential peculiarities of birds when he left the gallery, than when he entered it. But if, somewhere in that vast hall, there were a few preparations, exemplifying the leading structural peculiarities and the mode of development of a common fowl; if the types of the genera, the leading modifications in the skeleton, in the plumage at various ages, in the mode of nidification, and the like, among birds, were displayed; and if the other specimens were put away in a place where the men of science, to whom they are alone useful, could have free access to them, I can conceive that this collection might become a great instrument of scientific education. The last implement of the teacher to which I have adverted is examination--a means of education now so thoroughly understood that I need hardly enlarge upon it. I hold that both written and oral examinations are indispensable, and, by requiring the description of specimens, they may be made to supplement demonstration. Such is the fullest reply the time at my disposal will allow me to give to the question--how may a knowledge of zoology be best acquired and communicated? But there is a previous question which may be moved, and which, in fact, I know many are inclined to move. It is the question, why should training masters be encouraged to acquire a knowledge of this, or any other branch of physical science? What is the use, it is said, of attempting to make physical science a branch of primary education? It is not probable that teachers, in pursuing such studies, will be led astray from the acquirement of more important but less attractive knowledge? And, even if they can learn something of science without prejudice to their usefulness, what is the good of their attempting to instil that knowledge into boys whose real business is the acquisition of reading, writing, and arithmetic? These questions are, and will be, very commonly asked, for they arise from that profound ignorance of the value and true position of physical science, which infests the minds of the most highly educated and intelligent classes of the community. But if I did not feel well assured that they are capable of being easily and satisfactorily answered; that they have been answered over and over again; and that the time will come when men of liberal education will blush to raise such questions,--I should be ashamed of my position here to-night. Without doubt, it is your great and very important function to carry out elementary education; without question, anything that should interfere with the faithful fulfilment of that duty on your part would be a great evil; and if I thought that your acquirement of the elements of physical science, and your communication of those elements to your pupils, involved any sort of interference with your proper duties, I should be the first person to protest against your being encouraged to do anything of the kind. But is it true that the acquisition of such a knowledge of science as is proposed, and the communication of that knowledge, are calculated to weaken your usefulness? Or may I not rather ask, is it possible for you to discharge your functions properly without these aids? What is the purpose of primary intellectual education? I apprehend that its first object is to train the young in the use of those tools wherewith men extract knowledge from the ever-shifting succession of phenomena which pass before their eyes; and that its second object is to inform them of the fundamental laws which have been found by experience to govern the course of things, so that they may not be turned out into the world naked, defenceless, and a prey to the events they might control. A boy is taught to read his own and other languages, in order that he may have access to infinitely wider stores of knowledge than could ever be opened to him by oral intercourse with his fellow men; he learns to write, that his means of communication with the rest of mankind may be indefinitely enlarged, and that he may record and store up the knowledge he acquires. He is taught elementary mathematics, that he may understand all those relations of number and form, upon which the transactions of men, associated in complicated societies, are built, and that he may have some practice in deductive reasoning. All these operations of reading, writing, and ciphering, are intellectual tools, whose use should, before all things, be learned, and learned thoroughly; so that the youth may be enabled to make his life that which it ought to be, a continual progress in learning and in wisdom. But, in addition, primary education endeavours to fit a boy out with a certain equipment of positive knowledge. He is taught the great laws of morality; the religion of his sect; so much history and geography as will tell him where the great countries of the world are, what they are, and how they have become what they are. Without doubt all these are most fitting and excellent things to teach a boy; I should be very sorry to omit any of them from any scheme of primary intellectual education. The system is excellent, so far as it goes. But if I regard it closely, a curious reflection arises. I suppose that, fifteen hundred years ago, the child of any well-to-do Roman citizen was taught just these same things; reading and writing in his own, and, perhaps, the Greek tongue; the elements of mathematics; and the religion, morality, history, and geography current in his time. Furthermore, I do not think I err in affirming, that, if such a Christian Roman boy, who had finished his education, could be transplanted into one of our public schools, and pass through its course of instruction, he would not meet with a single unfamiliar line of thought; amidst all the new facts he would have to learn, not one would suggest a different mode of regarding the universe from that current in his own time. And yet surely there is some great difference between the civilization of the fourth century and that of the nineteenth, and still more between the intellectual habits and tone of thought of that day and this? And what has made this difference? I answer fearlessly,--The prodigious development of physical science within the last two centuries. Modern civilization rests upon physical science; take away her gifts to our own country, and our position among the leading nations of the world is gone to-morrow; for it is physical science only, that makes intelligence and moral energy stronger than brute force. The whole of modern thought is steeped in science; it has made its way into the works of our best poets, and even the mere man of letters, who affects to ignore and despise science, is unconsciously impregnated with her spirit, and indebted for his best products to her methods. I believe that the greatest intellectual revolution mankind has yet seen is now slowly taking place by her agency. She is teaching the world that the ultimate court of appeal is observation and experiment, and not authority; she is teaching it to estimate the value of evidence; she is creating a firm and living faith in the existence of immutable moral and physical laws, perfect obedience to which is the highest possible aim of an intelligent being. But of all this your old stereotyped system of education takes no note. Physical science, its methods, its problems, and its difficulties, will meet the poorest boy at every turn, and yet we educate him in such a manner that he shall enter the world as ignorant of the existence of the methods and facts of science as the day he was born. The modern world is full of artillery; and we turn out our children to do battle in it, equipped with the shield and sword of an ancient gladiator. Posterity will cry shame on us if we do not remedy this deplorable state of things. Nay, if we live twenty years longer, our own consciences will cry shame on us. It is my firm conviction that the only way to remedy it is, to make the elements of physical science an integral part of primary education. I have endeavoured to show you how that may be done for that branch of science which it is my business to pursue; and I can but add, that I should look upon the day when every schoolmaster throughout this land was a centre of genuine, however rudimentary, scientific knowledge, as an epoch in the history of the country. But let me entreat you to remember my last words. Addressing myself to you, as teachers, I would say, mere book learning in physical science is a sham and a delusion--what you teach, unless you wish to be impostors, that you must first know; and real knowledge in science means personal acquaintance with the facts, be they few or many.[9] FOOTNOTE: [9] It has been suggested to me that these words may be taken to imply a discouragement on my part of any sort of scientific instruction which does not give an acquaintance with the facts at first hand. But this is not my meaning. The ideal of scientific teaching is, no doubt, a system by which the scholar sees every fact for himself, and the teacher supplies only the explanations. Circumstances, however, do not often allow of the attainment of that ideal, and we must put up with the next best system--one in which the scholar takes a good deal on trust from a teacher, who, knowing the facts by his own knowledge, can describe them with so much vividness as to enable his audience to form competent ideas concerning them. The system which I repudiate is that which allows teachers who have not come into direct contact with the leading facts of a science to pass their second-hand information on. The scientific virus, like vaccine lymph, if passed through too long a succession of organisms, will lose all its effect in protecting the young against the intellectual epidemics to which they are exposed. VII. ON THE PHYSICAL BASIS OF LIFE.[10] In order to make the title of this discourse generally intelligible, I have translated the term "Protoplasm," which is the scientific name of the substance of which I am about to speak, by the words "the physical basis of life." I suppose that, to many, the idea that there is such a thing as a physical basis, or matter, of life may be novel--so widely spread is the conception of life as a something which works through matter, but is independent of it; and even those who are aware that matter and life are inseparably connected, may not be prepared for the conclusion plainly suggested by the phrase, "_the_ physical basis or matter of life," that there is some one kind of matter which is common to all living beings, and that their endless diversities are bound together by a physical, as well as an ideal, unity. In fact, when first apprehended, such a doctrine as this appears almost shocking to common sense. What, truly, can seem to be more obviously different from one another in faculty, in form, and in substance, than the various kinds of living beings? What community of faculty can there be between the brightly-coloured lichen, which so nearly resembles a mere mineral incrustation of the bare rock on which it grows, and the painter, to whom it is instinct with beauty, or the botanist, whom it feeds with knowledge? Again, think of the microscopic fungus--a mere infinitesimal ovoid particle, which finds space and duration enough to multiply into countless millions in the body of a living fly; and then of the wealth of foliage, the luxuriance of flower and fruit, which lies between this bald sketch of a plant and the giant pine of California, towering to the dimensions of a cathedral spire, or the Indian fig, which covers acres with its profound shadow, and endures while nations and empires come and go around its vast circumference? Or, turning to the other half of the world of life, picture to yourselves the great Finner whale, hugest of beasts that live, or have lived, disporting his eighty or ninety feet of bone, muscle, and blubber, with easy roll, among waves in which the stoutest ship that ever left dockyard would founder hopelessly; and contrast him with the invisible animalcules--mere gelatinous specks, multitudes of which could, in fact, dance upon the point of a needle with the same ease as the angels of the Schoolmen could, in imagination. With these images before your minds, you may well ask, what community of form, or structure, is there between the animalcule and the whale; or between the fungus and the fig-tree? And, _à fortiori_, between all four? Finally, if we regard substance, or material composition, what hidden bond can connect the flower which a girl wears in her hair and the blood which courses through her youthful veins; or, what is there in common between the dense and resisting mass of the oak, or the strong fabric of the tortoise, and those broad disks of glassy jelly which may be seen pulsating through the waters of a calm sea, but which drain away to mere films in the hand which raises them out of their element? Such objections as these must, I think, arise in the mind of every one who ponders, for the first time, upon the conception of a single physical basis of life underlying all the diversities of vital existence; but I propose to demonstrate to you that, notwithstanding these apparent difficulties, a threefold unity--namely, a unity of power, or faculty, a unity of form, and a unity of substantial composition--does pervade the whole living world. No very abstruse argumentation is needed, in the first place, to prove that the powers, or faculties, of all kinds of living matter, diverse as they may be in degree, are substantially similar in kind. Goethe has condensed a survey of all the powers of mankind into the well-known epigram:-- "Warum treibt sich das Volk so und schreit? Es will sich ernähren Kinder zeugen, und die nähren so gut es vermag. * * * * * Weiter bringt es kein Mensch, stell' er sich wie er auch will." In physiological language this means, that all the multifarious and complicated activities of man are comprehensible under three categories. Either they are immediately directed towards the maintenance and development of the body, or they effect transitory changes in the relative positions of parts of the body, or they tend towards the continuance of the species. Even those manifestations of intellect, of feeling, and of will, which we rightly name the higher faculties, are not excluded from this classification, inasmuch as to every one but the subject of them, they are known only as transitory changes in the relative positions of parts of the body. Speech, gesture, and every other form of human action are, in the long run, resolvable into muscular contraction, and muscular contraction is but a transitory change in the relative positions of the parts of a muscle. But the scheme which is large enough to embrace the activities of the highest form of life, covers all those of the lower creatures. The lowest plant, or animalcule, feeds, grows, and reproduces its kind. In addition, all animals manifest those transitory changes of form which we class under irritability and contractility; and, it is more than probable, that when the vegetable world is thoroughly explored, we shall find all plants in possession of the same powers, at one time or other of their existence. I am not now alluding to such phænomena, at once rare and conspicuous, as those exhibited by the leaflets of the sensitive plant, or the stamens of the barberry, but to much more widely-spread, and, at the same time, more subtle and hidden, manifestations of vegetable contractility. You are doubtless aware that the common nettle owes its stinging property to the innumerable stiff and needle-like, though exquisitely delicate, hairs which cover its surface. Each stinging-needle tapers from a broad base to a slender summit, which, though rounded at the end, is of such microscopic fineness that it readily penetrates, and breaks off in, the skin. The whole hair consists of a very delicate outer case of wood, closely applied to the inner surface of which is a layer of semifluid matter, full of innumerable granules of extreme minuteness. This semi-fluid lining is protoplasm, which thus constitutes a kind of bag, full of a limpid liquid, and roughly corresponding in form with the interior of the hair which it fills. When viewed with a sufficiently high magnifying power, the protoplasmic layer of the nettle hair is seen to be in a condition of unceasing activity. Local contractions of the whole thickness of its substance pass slowly and gradually from point to point, and give rise to the appearance of progressive waves, just as the bending of successive stalks of corn by a breeze produces the apparent billows of a corn-field. But, in addition to these movements, and independently of them, the granules are driven, in relatively rapid streams, through channels in the protoplasm which seem to have a considerable amount of persistence. Most commonly, the currents in adjacent parts of the protoplasm take similar directions; and, thus, there is a general stream up one side of the hair and down the other. But this does not prevent the existence of partial currents which take different routes; and, sometimes, trains of granules may be seen coursing swiftly in opposite directions, within a twenty-thousandth of an inch of one another; while, occasionally, opposite streams come into direct collision, and, after a longer or shorter struggle, one predominates. The cause of these currents seems to lie in contractions of the protoplasm which bounds the channels in which they flow, but which are so minute that the best microscopes show only their effects, and not themselves. The spectacle afforded by the wonderful energies prisoned within the compass of the microscopic hair of a plant, which we commonly regard as a merely passive organism, is not easily forgotten by one who has watched its display, continued hour after hour, without pause or sign of weakening. The possible complexity of many other organic forms, seemingly as simple as the protoplasm of the nettle, dawns upon one; and the comparison of such a protoplasm to a body with an internal circulation, which has been put forward by an eminent physiologist, loses much of its startling character. Currents similar to those of the hairs of the nettle have been observed in a great multitude of very different plants, and weighty authorities have suggested that they probably occur, in more or less perfection, in all young vegetable cells. If such be the case, the wonderful noonday silence of a tropical forest is, after all, due only to the dulness of our hearing; and could our ears catch the murmur of these tiny Maelstroms, as they whirl in the innumerable myriads of living cells which constitute each tree, we should be stunned, as with the roar of a great city. Among the lower plants, it is the rule rather than the exception, that contractility should be still more openly manifested at some periods of their existence. The protoplasm of _Algæ_ and _Fungi_ becomes, under many circumstances, partially, or completely, freed from its woody case, and exhibits movements of its whole mass, or is propelled by the contractility of one, or more, hair-like prolongations of its body, which are called vibratile cilia. And, so far as the conditions of the manifestation of the phænomena of contractility have yet been studied, they are the same for the plant as for the animal. Heat and electric shocks influence both, and in the same way, though it may be in different degrees. It is by no means my intention to suggest that there is no difference in faculty between the lowest plant and the highest, or between plants and animals. But the difference between the powers of the lowest plant, or animal, and those of the highest, is one of degree, not of kind, and depends, as Milne-Edwards long ago so well pointed out, upon the extent to which the principle of the division of labour is carried out in the living economy. In the lowest organism all parts are competent to perform all functions, and one and the same portion of protoplasm may successively take on the function of feeding, moving, or reproducing apparatus. In the highest, on the contrary, a great number of parts combine to perform each function, each part doing its allotted share of the work with great accuracy and efficiency, but being useless for any other purpose. On the other hand, notwithstanding all the fundamental resemblances which exist between the powers of the protoplasm in plants and in animals, they present a striking difference (to which I shall advert more at length presently), in the fact that plants can manufacture fresh protoplasm out of mineral compounds, whereas animals are obliged to procure it ready made, and hence, in the long run, depend upon plants. Upon what condition this difference in the powers of the two great divisions of the world of life depends, nothing is at present known. With such qualification as arises out of the last-mentioned fact, it may be truly said that the acts of all living things are fundamentally one. Is any such unity predicable of their forms? Let us seek in easily verified facts for a reply to this question. If a drop of blood be drawn by pricking one's finger, and viewed with proper precautions and under a sufficiently high microscopic power, there will be seen, among the innumerable multitude of little, circular, discoidal bodies, or corpuscles, which float in it and give it its colour, a comparatively small number of colourless corpuscles, of somewhat larger size and very irregular shape. If the drop of blood be kept at the temperature of the body, these colourless corpuscles will be seen to exhibit a marvellous activity, changing their forms with great rapidity, drawing in and thrusting out prolongations of their substance, and creeping about as if they were independent organisms. The substance which is thus active is a mass of protoplasm, and its activity differs in detail, rather than in principle, from that of the protoplasm of the nettle. Under sundry circumstances the corpuscle dies and becomes distended into a round mass, in the midst of which is seen a smaller spherical body, which existed, but was more or less hidden, in the living corpuscle, and is called its _nucleus_. Corpuscles of essentially similar structure are to be found in the skin, in the lining of the mouth, and scattered through the whole framework of the body. Nay, more; in the earliest condition of the human organism, in that state in which it has but just become distinguishable from the egg in which it arises, it is nothing but an aggregation of such corpuscles, and every organ of the body was, once, no more than such an aggregation. Thus a nucleated mass of protoplasm turns out to be what may be termed the structural unit of the human body. As a matter of fact, the body, in its earliest state, is a mere multiple of such units; and, in its perfect condition, it is a multiple of such units, variously modified. But does the formula which expresses the essential structural character of the highest animal cover all the rest, as the statement of its powers and faculties covered that of all others? Very nearly. Beast and fowl, reptile and fish, mollusk, worm, and polype, are all composed of structural units of the same character, namely, masses of protoplasm with a nucleus. There are sundry very low animals, each of which, structurally, is a mere colourless blood-corpuscle, leading an independent life. But, at the very bottom of the animal scale, even this simplicity becomes simplified, and all the phænomena of life are manifested by a particle of protoplasm without a nucleus. Nor are such organisms insignificant by reason of their want of complexity. It is a fair question whether the protoplasm of those simplest forms of life, which people an immense extent of the bottom of the sea, would not outweigh that of all the higher living beings which inhabit the land put together. And in ancient times, no less than at the present day, such living beings as these have been the greatest of rock builders. What has been said of the animal world is no less true of plants. Imbedded in the protoplasm at the broad, or attached, end of the nettle hair, there lies a spheroidal nucleus. Careful examination further proves that the whole substance of the nettle is made up of a repetition of such masses of nucleated protoplasm, each contained in a wooden case, which is modified in form, sometimes into a woody fibre, sometimes into a duct or spiral vessel, sometimes into a pollen grain, or an ovule. Traced back to its earliest state, the nettle arises as the man does, in a particle of nucleated protoplasm. And in the lowest plants, as in the lowest animals, a single mass of such protoplasm may constitute the whole plant, or the protoplasm may exist without a nucleus. Under these circumstances it may well be asked, how is one mass of non-nucleated protoplasm to be distinguished from another? why call one "plant" and the other "animal"? The only reply is that, so far as form is concerned, plants and animals are not separable, and that, in many cases, it is a mere matter of convention whether we call a given organism an animal or a plant. There is a living body called _Æthalium septicum_, which appears upon decaying vegetable substances, and, in one of its forms, is common upon the surfaces of tan-pits. In this condition it is, to all intents and purposes, a fungus, and formerly was always regarded as such; but the remarkable investigations of De Bary have shown that, in another condition, the _Æthalium_ is an actively locomotive creature, and takes in solid matters, upon which, apparently, it feeds, thus exhibiting the most characteristic feature of animality. Is this a plant; or is it an animal? Is it both; or is it neither? Some decide in favour of the last supposition, and establish an intermediate kingdom, a sort of biological No Man's Land for all these questionable forms. But, as it is admittedly impossible to draw any distinct boundary line between this no man's land and the vegetable world on the one hand, or the animal, on the other, it appears to me that this proceeding merely doubles the difficulty which, before, was single. Protoplasm, simple or nucleated, is the formal basis of all life. It is the clay of the potter: which, bake it and paint it as he will, remains clay, separated by artifice, and not by nature, from the commonest brick or sun-dried clod. Thus it becomes clear that all living powers are cognate, and that all living forms are fundamentally of one character. The researches of the chemist have revealed a no less striking uniformity of material composition in living matter. In perfect strictness, it is true that chemical investigation can tell us little or nothing, directly, of the composition of living matter, inasmuch as such matter must needs die in the act of analysis,--and upon this very obvious ground, objections, which I confess seem to me to be somewhat frivolous, have been raised to the drawing of any conclusions whatever respecting the composition of actually living matter, from that of the dead matter of life, which alone is accessible to us. But objectors of this class do not seem to reflect that it is also, in strictness, true that we know nothing about the composition of any body whatever, as it is. The statement that a crystal of calc-spar consists of carbonate of lime, is quite true, if we only mean that, by appropriate processes, it may be resolved into carbonic acid and quicklime. If you pass the same carbonic acid over the very quicklime thus obtained, you will obtain carbonate of lime again; but it will not be calc-spar, nor anything like it. Can it, therefore, be said that chemical analysis teaches nothing about the chemical composition of calc-spar? Such a statement would be absurd; but it is hardly more so than the talk one occasionally hears about the uselessness of applying the results of chemical analysis to the living bodies which have yielded them. One fact, at any rate, is out of reach of such refinements, and this is, that all the forms of protoplasm which have yet been examined contain the four elements, carbon, hydrogen, oxygen, and nitrogen, in very complex union, and that they behave similarly towards several reagents. To this complex combination, the nature of which has never been determined with exactness, the name of Protein has been applied. And if we use this term with such caution as may properly arise out of our comparative ignorance of the things for which it stands, it may be truly said, that all protoplasm is proteinaceous; or, as the white, or albumen, of an egg is one of the commonest examples of a nearly pure protein matter, we may say that all living matter is more or less albuminoid. Perhaps it would not yet be safe to say that all forms of protoplasm are affected by the direct action of electric shocks; and yet the number of cases in which the contraction of protoplasm is shown to be effected by this agency increases every day. Nor can it be affirmed with perfect confidence, that all forms of protoplasm are liable to undergo that peculiar coagulation at a temperature of 40°--50° centigrade, which has been called "heat-stiffening," though Kühne's beautiful researches have proved this occurrence to take place in so many and such diverse living beings, that it is hardly rash to expect that the law holds good for all. Enough has, perhaps, been said to prove the existence of a general uniformity in the character of the protoplasm, or physical basis, of life, in whatever group of living beings it may be studied. But it will be understood that this general uniformity by no means excludes any amount of special modifications of the fundamental substance. The mineral, carbonate of lime, assumes an immense diversity of characters, though no one doubts that, under all these Protean changes, it is one and the same thing. And now, what is the ultimate fate, and what the origin, of the matter of life? Is it, as some of the older naturalists supposed, diffused throughout the universe in molecules, which are indestructible and unchangeable in themselves; but, in endless transmigration, unite in innumerable permutations, into the diversified forms of life we know? Or, is the matter of life composed of ordinary matter, differing from it only in the manner in which its atoms are aggregated? Is it built up of ordinary matter, and again resolved into ordinary matter when its work is done? Modern science does not hesitate a moment between these alternatives. Physiology writes over the portals of life-- "Debemur morti nos nostraque," with a profounder meaning than the Roman poet attached to that melancholy line. Under whatever disguise it takes refuge, whether fungus or oak, worm or man, the living protoplasm not only ultimately dies and is resolved into its mineral and lifeless constituents, but is always dying, and, strange as the paradox may sound, could not live unless it died. In the wonderful story of the "Peau de Chagrin," the hero becomes possessed of a magical wild ass' skin, which yields him the means of gratifying all his wishes. But its surface represents the duration of the proprietor's life; and for every satisfied desire the skin shrinks in proportion to the intensity of fruition, until at length life and the last handbreadth of the _peau de chagrin_ disappear with the gratification of a last wish. Balzac's studies had led him over a wide range of thought and speculation, and his shadowing forth of physiological truth in this strange story may have been intentional. At any rate, the matter of life is a veritable _peau de chagrin_, and for every vital act it is somewhat the smaller. All work implies waste, and the work of life results, directly or indirectly, in the waste of protoplasm. Every word uttered by a speaker costs him some physical loss; and, in the strictest sense, he burns that others may have light--so much eloquence, so much of his body resolved into carbonic acid, water, and urea. It is clear that this process of expenditure cannot go on for ever. But happily, the protoplasmic _peau de chagrin_ differs from Balzac's in its capacity of being repaired, and brought back to its full size, after every exertion. For example, this present lecture, whatever its intellectual worth to you, has a certain physical value to me, which is, conceivably, expressible by the number of grains of protoplasm and other bodily substance wasted in maintaining my vital processes during its delivery. My _peau de chagrin_ will be distinctly smaller at the end of the discourse than it was at the beginning. By and by, I shall probably have recourse to the substance commonly called mutton, for the purpose of stretching it back to its original size. Now this mutton was once the living protoplasm, more or less modified, of another animal--a sheep. As I shall eat it, it is the same matter altered, not only by death, but by exposure to sundry artificial operations in the process of cooking. But these changes, whatever be their extent, have not rendered it incompetent to resume its old functions as matter of life. A singular inward laboratory, which I possess, will dissolve a certain portion of the modified protoplasm; the solution so formed will pass into my veins; and the subtle influences to which it will then be subjected will convert the dead protoplasm into living protoplasm, and transubstantiate sheep into man. Nor is this all. If digestion were a thing to be trifled with, I might sup upon lobster, and the matter of life of the crustacean would undergo the same wonderful metamorphosis into humanity. And were I to return to my own place by sea, and undergo shipwreck, the crustacea might, and probably would, return the compliment, and demonstrate our common nature by turning my protoplasm into living lobster. Or, if nothing better were to be had, I might supply my wants with mere bread, and I should find the protoplasm of the wheat-plant to be convertible into man, with no more trouble than that of the sheep, and with far less, I fancy, than that of the lobster. Hence it appears to be a matter of no great moment what animal, or what plant, I lay under contribution for protoplasm, and the fact speaks volumes for the general identity of that substance in all living beings. I share this catholicity of assimilation with other animals, all of which, so far as we know, could thrive equally well on the protoplasm of any of their fellows, or of any plant; but here the assimilative powers of the animal world cease. A solution of smelling-salts in water, with an infinitesimal proportion of some other saline matters, contains all the elementary bodies which enter into the composition of protoplasm; but, as I need hardly say, a hogshead of that fluid would not keep a hungry man from starving, nor would it save any animal whatever from a like fate. An animal cannot make protoplasm, but must take it ready-made from some other animal, or some plant--the animal's highest feat of constructive chemistry being to convert dead protoplasm into that living matter of life which is appropriate to itself. Therefore, in seeking for the origin of protoplasm, we must eventually turn to the vegetable world. The fluid containing carbonic acid, water, and ammonia, which offers such a Barmecide feast to the animal, is a table richly spread to multitudes of plants; and, with a due supply of only such materials, many a plant will not only maintain itself in vigour, but grow and multiply, until it has increased a million-fold, or a million million-fold, the quantity of protoplasm which it originally possessed; in this way building up the matter of life, to an indefinite extent, from the common matter of the universe. Thus, the animal can only raise the complex substance of dead protoplasm to the higher power, as one may say, of living protoplasm; while the plant can raise the less complex substances--carbonic acid, water, and ammonia--to the same stage of living protoplasm, if not to the same level. But the plant also has its limitations. Some of the fungi, for example, appear to need higher compounds to start with; and no known plant can live upon the uncompounded elements of protoplasm. A plant supplied with pure carbon, hydrogen, oxygen, and nitrogen, phosphorus, sulphur, and the like, would as infallibly die as the animal in his bath of smelling-salts, though it would be surrounded by all the constituents of protoplasm. Nor, indeed, need the process of simplification of vegetable food be carried so far as this, in order to arrive at the limit of the plant's thaumaturgy. Let water, carbonic acid, and all the other needful constituents be supplied with ammonia, and an ordinary plant will still be unable to manufacture protoplasm. Thus the matter of life, so far as we know it (and we have no right to speculate on any other), breaks up, in consequence of that continual death which is the condition of its manifesting vitality, into carbonic acid, water, and ammonia, which certainly possess no properties but those of ordinary matter. And out of these same forms of ordinary matter, and from none which are simpler, the vegetable world builds up all the protoplasm which keeps the animal world a going. Plants are the accumulators of the power which animals distribute and disperse. But it will be observed, that the existence of the matter of life depends on the pre-existence of certain compounds; namely, carbonic acid, water, and ammonia. Withdraw any one of these three from the world and all vital phænomena come to an end. They are related to the protoplasm of the plant, as the protoplasm of the plant is to that of the animal. Carbon, hydrogen, oxygen and nitrogen are all lifeless bodies. Of these, carbon and oxygen unite, in certain proportions and under certain conditions, to give rise to carbonic acid; hydrogen and oxygen produce water; nitrogen and hydrogen give rise to ammonia. These new compounds like the elementary bodies of which they are composed, are lifeless. But when they are brought together, under certain conditions they give rise to the still more complex body, protoplasm, and this protoplasm exhibits the phenomena of life. I see no break in this series of steps in molecular complication, and I am unable to understand why the language which is applicable to any one term of the series may not be used to any of the others. We think fit to call different kinds of matter carbon, oxygen, hydrogen, and nitrogen, and to speak of the various powers and activities of these substances as the properties of the matter of which they are composed. When hydrogen and oxygen are mixed in a certain proportion, and an electric spark is passed through them, they disappear, and a quantity of water, equal in weight to the sum of their weights, appears in their place. There is not the slightest parity between the passive and active powers of the water and those of the oxygen and hydrogen which have given rise to it. At 32° Fahrenheit, and far below that temperature, oxygen and hydrogen are elastic gaseous bodies, whose particles tend to rush away from one another with great force. Water, at the same temperature, is a strong though brittle solid, whose particles tend to cohere into definite geometrical shapes, and sometimes build up frosty imitations of the most complex forms of vegetable foliage. Nevertheless we call these, and many other strange phænomena, the properties of the water, and we do not hesitate to believe that, in some way or another, they result from the properties of the component elements of the water. We do not assume that a something called "aquosity" entered into and took possession of the oxide of hydrogen as soon as it was formed, and then guided the aqueous particles to their places in the facets of the crystal, or amongst the leaflets of the hoar-frost. On the contrary, we live in the hope and in the faith that, by the advance of molecular physics, we shall by and by be able to see our way as clearly from the constituents of water to the properties of water, as we are now able to deduce the operations of a watch from the form of its parts and the manner in which they are put together. Is the case in any way changed when carbonic acid, water, and ammonia disappear, and in their place, under the influence of pre-existing living protoplasm, an equivalent weight of the matter of life makes its appearance? It is true that there is no sort of parity between the properties of the components and the properties of the resultant, but neither was there in the case of the water. It is also true that what I have spoken of as the influence of pre-existing living matter is something quite unintelligible; but does anybody quite comprehend the _modus operandi_ of an electric spark, which traverses a mixture of oxygen and hydrogen? What justification is there, then, for the assumption of the existence in the living matter of a something which has no representative, or correlative, in the not living matter which gave rise to it? What better philosophical status has "vitality" than "aquosity"? And why should "vitality" hope for a better fate than the other "itys" which have disappeared since Martinus Scriblerus accounted for the operation of the meat-jack by its inherent "meat roasting quality," and scorned the "materialism" of those who explained the turning of the spit by a certain mechanism worked by the draught of the chimney? If scientific language is to possess a definite and constant signification whenever it is employed, it seems to me that we are logically bound to apply to the protoplasm, or physical basis of life, the same conceptions as those which are held to be legitimate elsewhere. If the phænomena exhibited by water are its properties, so are those presented by protoplasm, living or dead, its properties. If the properties of water may be properly said to result from the nature and disposition of its component molecules, I can find no intelligible ground for refusing to say that the properties of protoplasm result from the nature and disposition of its molecules. But I bid you beware that, in accepting these conclusions, you are placing your feet on the first rung of a ladder which, in most people's estimation, is the reverse of Jacob's, and leads to the antipodes of heaven. It may seem a small thing to admit that the dull vital actions of a fungus, or a foraminifer, are the properties of their protoplasm, and are the direct results of the nature of the matter of which they are composed. But if, as I have endeavoured to prove to you, their protoplasm is essentially identical with, and most readily converted into, that of any animal, I can discover no logical halting-place between the admission that such is the case, and the further concession that all vital action may, with equal propriety, be said to be the result of the molecular forces of the protoplasm which displays it. And if so, it must be true, in the same sense and to the same extent, that the thoughts to which I am now giving utterance, and your thoughts regarding them, are the expression of molecular changes in that matter of life which is the source of our other vital phænomena. Past experience leads me to be tolerably certain that, when the propositions I have just placed before you are accessible to public comment and criticism, they will be condemned by many zealous persons, and perhaps by some few of the wise and thoughtful. I should not wonder if "gross and brutal materialism" were the mildest phrase applied to them in certain quarters. And, most undoubtedly, the terms of the propositions are distinctly materialistic. Nevertheless two things are certain: the one, that I hold the statements to be substantially true; the other, that I, individually, am no materialist, but, on the contrary, believe materialism to involve grave philosophical error. This union of materialistic terminology with the repudiation of materialistic philosophy, I share with some of the most thoughtful men with whom I am acquainted. And, when I first undertook to deliver the present discourse, it appeared to me to be a fitting opportunity to explain how such a union is not only consistent with, but necessitated by, sound logic. I purposed to lead you through the territory of vital phenomena to the materialistic slough in which you find yourselves now plunged, and then to point out to you the sole path by which, in my judgment, extrication is possible. An occurrence of which I was unaware until my arrival here last night, renders this line of argument singularly opportune. I found in your papers the eloquent address "On the Limits of Philosophical Inquiry," which a distinguished prelate of the English Church delivered before the members of the Philosophical Institution on the previous day. My argument, also, turns upon this very point of the limits of philosophical inquiry; and I cannot bring out my own views better than by contrasting them with those so plainly, and, in the main, fairly, stated by the Archbishop of York. But I may be permitted to make a preliminary comment upon an occurrence that greatly astonished me. Applying the name of "the New Philosophy" to that estimate of the limits of philosophical inquiry which I, in common with many other men of science, hold to be just, the Archbishop opens his address by identifying this "New Philosophy" with the Positive Philosophy of M. Comte (of whom he speaks as its "founder"); and then proceeds to attack that philosopher and his doctrines vigorously. Now, so far as I am concerned, the most reverend prelate might dialectically hew M. Comte in pieces, as a modern Agag, and I should not attempt to stay his hand. In so far as my study of what specially characterises the Positive Philosophy has led me, I find therein little or nothing of any scientific value, and a great deal which is as thoroughly antagonistic to the very essence of science as anything in ultramontane Catholicism. In fact, M. Comte's philosophy in practice might be compendiously described as Catholicism _minus_ Christianity. But what has Comtism to do with the "New Philosophy," as the Archbishop defines it in the following passage? "Let me briefly remind you of the leading principles of this new philosophy. "All knowledge is experience of facts acquired by the senses. The traditions of older philosophies have obscured our experience by mixing with it much that the senses cannot observe, and until these additions are discarded our knowledge is impure. Thus metaphysics tell us that one fact which we observe is a cause, and another is the effect of that cause; but upon a rigid analysis, we find that our senses observe nothing of cause or effect: they observe, first, that one fact succeeds another, and, after some opportunity, that this fact has never failed to follow--that for cause and effect we should substitute invariable succession. An older philosophy teaches us to define an object by distinguishing its essential from its accidental qualities: but experience knows nothing of essential and accidental; she sees only that certain marks attach to an object, and, after many observations, that some of them attach invariably, whilst others may at times be absent.... As all knowledge is relative, the notion of anything being necessary must be banished with other traditions."[11] There is much here that expresses the spirit of the "New Philosophy," if by that term be meant the spirit of modern science; but I cannot but marvel that the assembled wisdom and learning of Edinburgh should have uttered no sign of dissent, when Comte was declared to be the founder of these doctrines. No one will accuse Scotchmen of habitually forgetting their great countrymen; but it was enough to make David Hume turn in his grave, that here, almost within earshot of his house, an instructed audience should have listened, without a murmur, while his most characteristic doctrines were attributed to a French writer of fifty years later date, in whose dreary and verbose pages we miss alike the vigour of thought and the exquisite clearness of style of the man whom I make bold to term the most acute thinker of the eighteenth century--even though that century produced Kant. But I did not come to Scotland to vindicate the honour of one of the greatest men she has ever produced. My business is to point out to you that the only way of escape out of the crass materialism in which we just now landed, is the adoption and strict working-out of the very principles which the Archbishop holds up to reprobation. Let us suppose that knowledge is absolute, and not relative, and therefore, that our conception of matter represents that which it really is. Let us suppose, further, that we do know more of cause and effect than a certain definite order of succession among facts, and that we have a knowledge of the necessity of that succession--and hence, of necessary laws--and I, for my part, do not see what escape there is from utter materialism and necessarianism. For it is obvious that our knowledge of what we call the material world, is, to begin with, at least as certain and definite as that of the spiritual world, and that our acquaintance with law is of as old a date as our knowledge of spontaneity. Further, I take it to be demonstrable that it is utterly impossible to prove that anything whatever may not be the effect of a material and necessary cause, and that human logic is equally incompetent to prove that any act is really spontaneous. A really spontaneous act is one which, by the assumption, has no cause; and the attempt to prove such a negative as this is, on the face of the matter, absurd. And while it is thus a philosophical impossibility to demonstrate that any given phænomenon is not the effect of a material cause, any one who is acquainted with the history of science will admit, that its progress has, in all ages, meant, and now, more than ever, means, the extension of the province of what we call matter and causation, and the concomitant gradual banishment from all regions of human thought of what we call spirit and spontaneity. I have endeavoured, in the first part of this discourse, to give you a conception of the direction towards which modern physiology is tending; and I ask you, what is the difference between the conception of life as the product of a certain disposition of material molecules, and the old notion of an Archæus governing and directing blind matter within each living body, except this--that here, as elsewhere, matter and law have devoured spirit and spontaneity? And as surely as every future grows out of past and present, so will the physiology of the future gradually extend the realm of matter and law until it is co-extensive with knowledge, with feeling, and with action. The consciousness of this great truth weighs like a nightmare, I believe, upon many of the best minds of these days. They watch what they conceive to be the progress of materialism, in such fear and powerless anger as a savage feels, when, during an eclipse, the great shadow creeps over the face of the sun. The advancing tide of matter threatens to drown their souls; the tightening grasp of law impedes their freedom; they are alarmed lest man's moral nature be debased by the increase of his wisdom. If the "New Philosophy" be worthy of the reprobation with which it is visited, I confess their fears seem to me, to be well founded. While, on the contrary, could David Hume be consulted, I think he would smile at their perplexities, and chide them for doing even as the heathen, and falling down in terror before the hideous idols their own hands have raised. For, after all, what do we know of this terrible "matter," except as a name for the unknown and hypothetical cause of states of our own consciousness? And what do we know of that "spirit" over whose threatened extinction by matter a great lamentation is arising, like that which was heard at the death of Pan, except that it is also a name for an unknown and hypothetical cause, or condition, of states of consciousness? In other words, matter and spirit are but names for the imaginary substrata of groups of natural phænomena. And what is the dire necessity and "iron" law under which men groan? Truly, most gratuitously invented bugbears. I suppose if there be an "iron" law, it is that of gravitation; and if there be a physical necessity, it is that a stone, unsupported, must fall to the ground. But what is all we really know and can know about the latter phænomenon? Simply, that, in all human experience, stones have fallen to the ground under these conditions; that we have not the smallest reason for believing that any stone so circumstanced will not fall to the ground; and that we have, on the contrary, every reason to believe that it will so fall. It is very convenient to indicate that all the conditions of belief have been fulfilled in this case, by calling the statement that unsupported stones will fall to the ground, "a law of nature." But when, as commonly happens, we change _will_ into _must_, we introduce an idea of necessity which most assuredly does not lie in the observed facts, and has no warranty that I can discover elsewhere. For my part, I utterly repudiate and anathematize the intruder. Fact I know; and Law I know; but what is this Necessity, save an empty shadow of my own mind's throwing? But, if it is certain that we can have no knowledge of the nature of either matter or spirit, and that the notion of necessity is something illegitimately thrust into the perfectly legitimate conception of law, the materialistic position that there is nothing in the world but matter, force, and necessity, is as utterly devoid of justification as the most baseless of theological dogmas. The fundamental doctrines of materialism, like those of spiritualism, and most other "isms," lie outside "the limits of philosophical inquiry," and David Hume's great service to humanity is his irrefragable demonstration of what these limits are. Hume called himself a sceptic, and therefore others cannot be blamed if they apply the same title to him; but that does not alter the fact that the name, with its existing implications, does him gross injustice. If a man asks me what the politics of the inhabitants of the moon are, and I reply that I do not know; that neither I, nor any one else, have any means of knowing; and that, under these circumstances, I decline to trouble myself about the subject at all, I do not think he has any right to call me a sceptic. On the contrary, in replying thus, I conceive that I am simply honest and truthful, and show a proper regard for the economy of time. So Hume's strong and subtle intellect takes up a great many problems about which we are naturally curious, and shows us that they are essentially questions of lunar politics, in their essence incapable of being answered, and therefore not worth the attention of men who have work to do in the world. And he thus ends one of his essays:-- "If we take in hand any volume of Divinity, or school metaphysics, for instance, let us ask, _Does it contain any abstract reasoning concerning quantity or number_? No. _Does it contain any experimental reasoning concerning matter of fact and existence_? No. Commit it then to the flames; for it can contain nothing but sophistry and illusion."[12] Permit me to enforce this most wise advice. Why trouble ourselves about matters of which, however important they may be, we do know nothing, and can know nothing? We live in a world which is full of misery and ignorance, and the plain duty of each and all of us is to try to make the little corner he can influence somewhat less miserable and somewhat less ignorant than it was before he entered it. To do this effectually it is necessary to be fully possessed of only two beliefs: the first, that the order of nature is ascertainable by our faculties to an extent which is practically unlimited; the second, that our volition counts for something as a condition of the course of events. Each of these beliefs can be verified experimentally, as often as we like to try. Each, therefore, stands upon the strongest foundation upon which any belief can rest, and forms one of our highest truths. If we find that the ascertainment of the order of nature is facilitated by using one terminology, or one set of symbols, rather than another, it is our clear duty to use the former; and no harm can accrue, so long as we bear in mind, that we are dealing merely with terms and symbols. In itself it is of little moment whether we express the phænomena of matter in terms of spirit; or the phænomena of spirit, in terms of matter: matter may be regarded as a form of thought, thought may be regarded as a property of matter--each statement has a certain relative truth. But with a view to the progress of science, the materialistic terminology is in every way to be preferred. For it connects thought with the other phænomena of the universe, and suggests inquiry into the nature of those physical conditions, or concomitants of thought, which are more or less accessible to us, and a knowledge of which may, in future, help us to exercise the same kind of control over the world of thought, as we already possess in respect of the material world; whereas, the alternative, or spiritualistic, terminology is utterly barren, and leads to nothing but obscurity and confusion of ideas. Thus there can be little doubt, that the further science advances, the more extensively and consistently will all the phænomena of nature be represented by materialistic formulæ and symbols. But the man of science, who, forgetting the limits of philosophical inquiry, slides from these formulæ and symbols into what is commonly understood by materialism, seems to me to place himself on a level with the mathematician, who should mistake the _x_'s and _y_'s, with which he works his problems, for real entities--and with this further disadvantage, as compared with the mathematician, that the blunders of the latter are of no practical consequence, while the errors of systematic materialism may paralyse the energies and destroy the beauty of a life. FOOTNOTES: [10] The substance of this paper was contained in a discourse which was delivered in Edinburgh on the evening of Sunday, the 8th of November, 1868--being the first of a series of Sunday evening addresses upon non-theological topics, instituted by the Rev. J. Cranbrook. Some phrases, which could possess only a transitory and local interest, have been omitted; instead of the newspaper report of the Archbishop of York's address, his Grace's subsequently-published pamphlet "On the Limits of Philosophical Inquiry" is quoted; and I have, here and there, endeavoured to express my meaning more fully and clearly than I seem to have done in speaking--if I may judge by sundry criticisms upon what I am supposed to have said, which have appeared. But in substance, and, so far as my recollection serves, in form, what is here written corresponds with what was there said. [11] "The Limits of Philosophical Inquiry," pp. 4 and 5. [12] Hume's Essay "Of the Academical or Sceptical Philosophy," in the "Inquiry concerning the Human Understanding." VIII. THE SCIENTIFIC ASPECTS OF POSITIVISM. It is now some sixteen or seventeen years since I became acquainted with the "Philosophic Positive," the "Discours sur l'Ensemble du Positivisme," and the "Politique Positive" of Auguste Comte. I was led to study these works partly by the allusions to them in Mr. Mill's "Logic," partly by the recommendation of a distinguished theologian, and partly by the urgency of a valued friend, the late Professor Henfrey, who looked upon M. Comte's bulky volumes as a mine of wisdom, and lent them to me that I might dig and be rich. After due perusal, I found myself in a position to echo my friend's words, though I may have laid more stress on the "mine" than on the "wisdom." For I found the veins of ore few and far between, and the rock so apt to run to mud, that one incurred the risk of being intellectually smothered in the working. Still, as I was glad to acknowledge, I did come to a nugget here and there; though not, so far as my experience went, in the discussions on the philosophy of the physical sciences, but in the chapters on speculative and practical sociology. In these there was indeed much to arouse the liveliest interest in one whose boat had broken away from the old moorings, and who had been content "to lay out an anchor by the stern" until daylight should break and the fog clear. Nothing could be more interesting to a student of biology than to see the study of the biological sciences laid down, as an essential part of the prolegomena of a new view of social phenomena. Nothing could be more satisfactory to a worshipper of the severe truthfulness of science than the attempt to dispense with all beliefs, save such as could brave the light, and seek, rather than fear, criticism; while, to a lover of courage and outspokenness, nothing could be more touching than the placid announcement on the title-page of the "Discours sur l'Ensemble du Positivisme," that its author proposed "Réorganiser, sans Dieu ni roi, Par le culte systématique de l'Humanité," the shattered frame of modern society. In those days I knew my "Faust" pretty well, and, after reading this word of might, I was minded to chant the well-known stanzas of the "Geisterchor"-- "Weh! Weh! Die schöne welt. Sie stürzt, sie zerfällt Wir tragen Die Trümmern ins Nichts hinüber. Mächtiger Der Erdensöhne, Prächtiger, Baue sie wieder In deinem Busen baue sie auf." Great, however, was my perplexity, not to say disappointment, as I followed the progress of this "mighty son of earth" in his work of reconstruction. Undoubtedly "Dieu" disappeared, but the "Nouveau Grand-Être Suprême," a gigantic fetish, turned out bran-new by M. Comte's own hands, reigned in his stead. "Roi" also was not heard of; but, in his place, I found a minutely-defined social organization, which, if it ever came into practice, would exert a despotic authority such as no sultan has rivalled, and no Puritan presbytery, in its palmiest days, could hope to excel. While, as for the "culte systématique de l'Humanité," I, in my blindness, could not distinguish it from sheer Popery, with M. Comte in the chair of St. Peter, and the names of most of the saints changed. To quote "Faust" again, I found myself saying with Gretchen,-- "Ungefähr sagt das der Pfarrer auch Nur mit ein bischen andern Worten." Rightly or wrongly, this was the impression which, all those years ago, the study of M. Comte's works left on my mind, combined with the conviction, which I shall always be thankful to him for awakening in me, that the organization of society upon a new and purely scientific basis is not only practicable, but is the only political object much worth fighting for. As I have said, that part of M. Comte's writings which deals with the philosophy of physical science appeared to me to possess singularly little value, and to show that he had but the most superficial, and merely second-hand, knowledge of most branches of what is usually understood by science. I do not mean by this merely to say that Comte was behind our present knowledge, or that he was unacquainted with the details of the science of his own day. No one could justly make such defects cause of complaint in a philosophical writer of the past generation. What struck me was his want of apprehension of the great features of science; his strange mistakes as to the merits of his scientific contemporaries; and his ludicrously erroneous notions about the part which some of the scientific doctrines current in his time were destined to play in the future. With these impressions in my mind, no one will be surprised if I acknowledge that, for these sixteen years, it has been a periodical source of irritation to me to find M. Comte put forward as a representative of scientific thought; and to observe that writers whose philosophy had its legitimate parent in Hume, or in themselves, were labelled "Comtists" or "Positivists" by public writers, even in spite of vehement protests to the contrary. It has cost Mr. Mill hard rubbings to get that label off; and I watch Mr. Spencer, as one regards a good man struggling with adversity, still engaged in eluding its adhesiveness, and ready to tear away skin and all, rather than let it stick. My own turn might come next; and, therefore, when an eminent prelate the other day gave currency and authority to the popular confusion, I took an opportunity of incidentally revindicating Hume's property in the so-called "New Philosophy," and, at the same time, of repudiating Comtism on my own behalf.[13] The few lines devoted to Comtism in my paper on the "Physical Basis of Life" were, in intention, strictly limited to these two purposes. But they seem to have given more umbrage than I intended they should, to the followers of M. Comte in this country, for some of whom, let me observe in passing, I entertain a most unfeigned respect; and Mr. Congreve's recent article gives expression to the displeasure which I have excited among the members of the Comtian body. Mr. Congreve, in a peroration which seems especially intended to catch the attention of his readers, indignantly challenges me to admire M. Comte's life, "to deny that it has a marked character of grandeur about it;" and he uses some very strong language because I show no sign of veneration for his idol. I confess I do not care to occupy myself with the denigration of a man who, on the whole, deserves to be spoken of with respect. Therefore, I shall enter into no statement of the reasons which lead me unhesitatingly to accept Mr. Congreve's challenge, and to refuse to recognise anything which deserves the name of grandeur of character in M. Comte, unless it be his arrogance, which is undoubtedly sublime. All I have to observe is, that if Mr. Congreve is justified in saying that I speak with a tinge of contempt for his spiritual father, the reason for such colouring of my language is to be found in the fact, that, when I wrote, I had but just arisen from the perusal of a work with which he is doubtless well acquainted, M. Littré's "Auguste Comte et la Philosophic Positive." Though there are tolerably fixed standards of right and wrong, and even of generosity and meanness, it may be said that the beauty, or grandeur, of a life is more or less a matter of taste; and Mr. Congreve's notions of literary excellence are so different from mine that, it may be, we should diverge as widely in our judgment of moral beauty or ugliness. Therefore, while retaining my own notions, I do not presume to quarrel with his. But when Mr. Congreve devotes a great deal of laboriously guarded insinuation to the endeavour to lead the public to believe that I have been guilty of the dishonesty of having criticised Comte without having read him, I must be permitted to remind him that he has neglected the well-known maxim of a diplomatic sage, "If you want to damage a man, you should say what is probable, as well as what is true." And when Mr. Congreve speaks of my having an advantage over him in my introduction of "Christianity" into the phrase that "M. Comte's philosophy, in practice, might be described as Catholicism _minus_ Christianity;" intending thereby to suggest that I have, by so doing, desired to profit by an appeal to the _odium theologicum_,--he lays himself open to a very unpleasant retort. What if I were to suggest that Mr. Congreve had not read Comte's works; and that the phrase "the context shows that the view of the writer ranges--however superficially--over the whole works. This is obvious from the mention of Catholicism," demonstrates that Mr. Congreve has no acquaintance with the "Philosophie Positive"? I think the suggestion would be very unjust and unmannerly, and I shall not make it. But the fact remains, that this little epigram of mine, which has so greatly provoked Mr. Congreve, is neither more nor less than a condensed paraphrase of the following passage, which is to be found at page 344 of the fifth volume of the "Philosophie Positive:"[14]-- "La seule solution possible de ce grand problème historique, qui n'a jamais pu être philosophiquement posé jusqu'ici, consiste à concevoir, en sens radicalement inverse des notions habituelles, _que ce qui devait nécessairement périr ainsi, dans le catholicisme, c'était la doctrine, et non l'organisation_, qui n'a été passagèrement ruinée que par suite de son inévitable adhérence élémentaire a la philosophie théologique, destinée à succomber graduellement sous l'irrésistible émancipation de la raison humaine; _tandis qu'une telle constitution, convenablement reconstruite sur des bases intellectuelles à la fois plus étendues et plus stables, devra finalement présider à l'indispensable réorganisation spirituelle des sociétés modernes, sauf les différences essentielles spontanément correspondantes à l'extrême diversité des doctrines fondamentales_; à moins de supposer, ce qui serait certainement contradictoire à l'ensemble des lois de notre nature, que les immenses efforts de tant de grands hommes, secondés par la persévérante sollicitude des nations civilisées, dans la fondation séculaire de ce chef-d'oeuvre politique de la sagesse humaine, doivent être enfin irrévocablement perdus pour l'élite de l'humanité sauf les résultats, capitaux mais provisoires, qui s'y rapportaient immédiatement. Cette explication générale, déjà évidemment motivée par la suite des considérations propres à ce chapitre, sera de plus en plus confirmée par tout le reste de notre opération historique, _dont elle constituera spontanément la principale conclusion politique."_ Nothing can be clearer. Comte's ideal, as stated by himself, is Catholic organization without Catholic doctrine, or, in other words, Catholicism _minus_ Christianity. Surely it is utterly unjustifiable to ascribe to me base motives for stating a man's doctrines, as nearly as may be, in his own words! My readers would hardly be interested were I to follow Mr. Congreve any further, or I might point out that the fact of his not having heard me lecture is hardly a safe ground for his speculations as to what I do not teach. Nor do I feel called upon to give any opinion as to M. Comte's merits or demerits as regards sociology. Mr. Mill (whose competence to speak on these matters I suppose will not be questioned, even by Mr. Congreve) has dealt with M. Comte's philosophy from this point of view, with a vigour and authority to which I cannot for a moment aspire; and with a severity, not unfrequently amounting to contempt, which I have not the wish, if I had the power, to surpass. I, as a mere student in these questions, am content to abide by Mr. Mill's judgment until some one shows cause for its reversal, and I decline to enter into a discussion which I have not provoked. The sole obligation which lies upon me is to justify so much as still remains without justification of what I have written respecting Positivism--namely, the opinion expressed in the following paragraph:-- "In so far as my study of what specially characterises the Positive Philosophy has led me, I find therein little or nothing of any scientific value, and a great deal which is as thoroughly antagonistic to the very essence of science as any thing in ultramontane Catholicism." Here are two propositions: the first, that the "Philosophie Positive" contains little or nothing of any scientific value; the second, that Comtism is, in spirit, anti-scientific. I shall endeavour to bring forward ample evidence in support of both. I. No one who possesses even a superficial acquaintance with physical science can read Comte's "Leçons" without becoming aware that he was at once singularly devoid of real knowledge on these subjects, and singularly unlucky. What is to be thought of the contemporary of Young and of Fresnel, who never misses an opportunity of casting scorn upon the hypothesis of an ether--the fundamental basis not only of the undulatory theory of light, but of so much else in modern physics--and whose contempt for the intellects of some of the strongest men of his generation was such, that he puts forward the mere existence of night as a refutation of the undulatory theory?[15] What a wonderful gauge of his own value as a scientific critic does he afford, by whom we are informed that phrenology is a great science, and psychology a chimæra; that Gall was one of the great men of his age, and that Cuvier was "brilliant but superficial"![16] How unlucky must one consider the bold speculator who, just before the dawn of modern histology--which is simply the application of the microscope to anatomy--reproves what he calls "the abuse of microscopic investigations," and "the exaggerated credit" attached to them; who, when the morphological uniformity of the tissues of the great majority of plants and animals was on the eve of being demonstrated, treated with ridicule those who attempt to refer all tissues to a "tissu générateur," formed by "le chimérique et inintelligible assemblage d'une sorte de monades organiques, qui seraient dès lors les vrais éléments primordiaux de tout corps vivant;"[17] and who finally tells us, that all the objections against a linear arrangement of the species of living beings are in their essence foolish, and that the order of the animal series is "necessarily linear,"[18] when the exact contrary is one of the best-established and the most important truths of zoology. Appeal to mathematicians, astronomers, physicists,[19] chemists, biologists, about the "Philosophie Positive," and they all, with one consent, begin to make protestation that, whatever M. Comte's other merits, he has shed no light upon the philosophy of their particular studies. To be just, however, it must be admitted that even M. Comte's most ardent disciples are content to be judiciously silent about his knowledge or appreciation of the sciences themselves, and prefer to base their master's claims to scientific authority upon his "law of the three states," and his "classification of the sciences." But here, also, I must join issue with them as completely as others--notably Mr. Herbert Spencer--have done before me. A critical examination of what M. Comte has to say about the "law of the three states" brings out nothing but a series of more or less contradictory statements of an imperfectly apprehended truth; and his "classification of the sciences," whether regarded historically or logically, is, in my judgment, absolutely worthless. Let us consider the law of "the three states" as it is put before us in the opening of the first Leçon of the "Philosophie Positive:"-- "En étudiant ainsi le développement total de l'intelligence humaine dans ses diverses sphères d'activité, depuis son premier essor le plus simple jusqu'à nos jours, je crois avoir découvert une grande loi fondamentale, à laquelle il est assujetti par une nécessité invariable, et qui me semble pouvoir être solidement établie, soit sur les preuves rationelles fournies par la connaissance de notre organisation, soit sur les vérifications historiques résultant d'un examen attentif du passé. Cette loi consiste en ce que chacune de nos conceptions principales, chaque branche de nos connaissances, passe successivement par trois états théoriques différents; l'état théologique, ou fictif; l'état métaphysique, ou abstrait; l'état scientifique, ou positif. En d'autres termes, l'esprit humain, par sa nature, emploie successivement dans chacune de ses recherches trois méthodes de philosopher, dont _le caractère est essentiellement différent et même radicalement opposé_; d'abord la méthode théologique, ensuite la méthode métaphysique, et enfin la méthode positive. De là, trois sortes de philosophie, ou de systèmes généraux de conceptions sur l'ensemble des phénomènes _qui s'excluent mutuellement_; la première est le point de départ nécessaire de l'intelligence humaine; la troisième, son état fixe et définitif; la seconde est uniquement destinée à servir de transition."[20] Nothing can be more precise than these statements, which may be put into the following propositions:-- (a) The human intellect is subjected to the law by an invariable necessity, which is demonstrable, _à priori_, from the nature and constitution of the intellect; while, as a matter of historical fact, the human intellect has been subjected to the law. (b) Every branch of human knowledge passes through the three states, necessarily beginning with the first stage. (c) The three states mutually exclude one another, being essentially different, and even radically opposed. Two questions present themselves. Is M. Comte consistent with himself in making these assertions? And is he consistent with fact? I reply to both questions in the negative; and, as regards the first, I bring forward as my witness a remarkable passage which is to be found in the fourth volume of the "Philosophic Positive" (p. 491), when M. Comte had had time to think out, a little more fully, the notions crudely stated in the first volume:-- "A proprement parler, la philosophie théologique, même dans notre première enfance, individuelle ou sociale, n'a jamais pu être rigoureusement universelle, c'est-à-dire que, pour les ordres quelconques de phénomènes, _les faits les plus simples et les plus communs ont toujours été regardés comme essentiellement assujettis à des lois naturelles, au lieu d'être attribués à l'arbitraire volonté des agents surnaturels_. L'illustre Adam Smith a, par example, très-heureusement remarqué dans ses essais philosophiques, qu'on ne trouvait, en aucun temps ni en aucun pays, un dieu pour la pesanteur. _Il en est ainsi, en général, même à l'égard des sujets les plus compliqués, envers tous les phénomènes assez élémentaires et assez familiers pour que la parfaite invariabilité de leurs relations effectives ait toujours dû frapper spontanément l'observateur le moins préparé_. Dans l'ordre moral et social, qu'une vaine opposition voudrait aujourd'hui systématiquement interdire à la philosophie positive, il y a eu nécessairement, en tout temps, la pensée des lois naturelles, relativement aux plus simples phénomènes de la vie journalière, comme l'exige évidemment la conduite générale de notre existence réelle, individuelle ou sociale, qui n'aurait pu jamais comporter aucune prévoyance quelconque, si tous les phénomènes humains avaient été rigoureusement attribués à des agents surnaturels, puisque dès lors la prière aurait logiquement constitué la seule ressource imaginable pour influer sur le cours habituel des actions humaines. _On doit même remarquer, à ce sujet, que c'est, au contraire, l'ébauche spontanée des premières lois naturelles propres aux actes individuels ou sociaux qui, fictivement transportée à tous les phénomènes du monde extérieur, a d'abord fourni, d'après nos explications précédentes, le vrai principe fondamental de la philosophie théologique. Ainsi, le germe élémentaire de la philosophie positive est certainement tout aussi primitif au fond que celui de la philosophie théologique elle-même, quoi qu'il n'ait pu se développer que beaucoup plus tard._ Une telle notion importe extrêmement à la parfaite rationalité de notre théorie sociologique, puisque la vie humaine ne pouvant jamais offrir aucune véritable création quelconque, mais toujours une simple évolution graduelle, l'essor final de l'esprit positif deviendrait scientifiquement incompréhensible, si, dès l'origine, on n'en concevait, à tous égards, les premiers rudiments nécessaires. Depuis cette situation primitive, à mesure que nos observations se sont spontanément étendues et généralisées, cet essor, d'abord à peine appréciable, a constamment suivi, sans cesser longtemps d'être subalterne, une progression très-lente, mais continue, la philosophie théologique restant toujours réservée pour les phénomènes, de moins en moins nombreux, dont les lois naturelles ne pouvaient encore être aucunement connues." Compare the propositions implicitly laid down here with those contained in the earlier volume. (a) As a matter of fact, the human intellect has _not_ been invariably subjected to the law of the three states, and therefore the necessity of the law _cannot_ be demonstrable _à priori_. (b) Much of our knowledge of all kinds has _not_ passed through the three states, and more particularly, as M. Comte is careful to point out, not through the first, (c) The positive state has more or less co-existed with the theological, from the dawn of human intelligence. And, by way of completing the series of contradictions, the assertion that the three states are "essentially different and even radically opposed," is met a little lower on the same page by the declaration that "the metaphysical state is, at bottom, nothing but a simple general modification of the first;" while, in the fortieth Leçon, as also in the interesting early essay entitled "Considérations philosophiques sur les Sciences et les Savants (1825)," the three states are practically reduced to two. "Le véritable esprit général de toute philosophie théologique ou métaphysique consiste à prendre pour principe, dans l'explication des phénomènes du monde extérieur, notre sentiment immédiat des phénomènes humains; tandis que au contraire, la philosophie positive est toujours caractérisée, non moins profondément, par la subordination nécessaire et rationnelle de la conception de l'homme à celle du monde."[21] I leave M. Cointe's disciples to settle which of these contradictory statements expresses their master's real meaning. All I beg leave to remark is, that men of science are not in the habit of paying much attention to "laws" stated in this fashion. The second statement is undoubtedly far more rational and consistent with fact than the first; but I cannot think it is a just or adequate account of the growth of intelligence, either in the individual man, or in the human species. Any one who will carefully watch the development of the intellect of a child will perceive that, from the first, its mind is mirroring nature in two different ways. On the one hand, it is merely drinking in sensations and building up associations, while it forms conceptions of things and their relations which are more thoroughly "positive," or devoid of entanglement with hypotheses of any kind, than they will ever be in after-life. No child has recourse to imaginary personifications in order to account for the ordinary properties of objects which are not alive, or do not represent living things. It does not imagine that the taste of sugar is brought about by a god of sweetness, or that a spirit of jumping causes a ball to bound. Such phænomena, which form the basis of a very large part of its ideas, are taken as matters of course--as ultimate facts which suggest no difficulty and need no explanation. So far as all these common, though important, phænomena are concerned, the child's mind is in what M. Comte would call the "positive" state. But, side by side with this mental condition, there rises another. The child becomes aware of itself as a source of action and a subject of passion and of thought. The acts which follow upon its own desires are among the most interesting and prominent of surrounding occurrences; and these acts, again, plainly arise either out of affections caused by surrounding things, or of other changes in itself. Among these surrounding things, the most interesting and important are mother and father, brethren and nurses. The hypothesis that these wonderful creatures are of like nature to itself is speedily forced upon the child's mind; and this primitive piece of anthropomorphism turns out to be a highly successful speculation, which finds its justification at every turn. No wonder, then, that it is extended to other similarly interesting objects which are not too unlike these--to the dog, the cat, and the canary, the doll, the toy, and the picture-book--that these are endowed with wills and affections, and with capacities for being "good" and "naughty." But surely it would be a mere perversion of language to call this a "theological" state of mind, either in the proper sense of the word "theological," or as contrasted with "scientific" or "positive." The child does not worship either father or mother, dog or doll. On the contrary, nothing is more curious than the absolute irreverence, if I may so say, of a kindly-treated young child; its tendency to believe in itself as the centre of the universe, and its disposition to exercise despotic tyranny over those who could crush it with a finger. Still less is there anything unscientific, or anti-scientific, in this infantile anthropomorphism. The child observes that many phænomena are the consequences of affections of itself; it soon has excellent reasons for the belief that many other phænomena are consequences of the affections of other beings, more or less like itself. And having thus good evidence for believing that many of the most interesting occurrences about it are explicable on the hypothesis that they are the work of intelligences like itself--having discovered a _vera causa_ for many phænomena--why should the child limit the application of so fruitful an hypothesis? The dog has a sort of intelligence, so has the cat; why should not the doll and the picture-book also have a share, proportioned to their likeness to intelligent things? The only limit which does arise is exactly that which, as a matter of science, should arise; that is to say, the anthropomorphic interpretation is applied only to those phænomena which, in their general nature, or their apparent capriciousness, resemble those which the child observes to be caused by itself, or by beings like itself. All the rest are regarded as things which explain themselves, or are inexplicable. It is only at a later stage of intellectual development that the intelligence of man awakes to the apparent conflict between the anthropomorphic, and what I may call the physical,[22] aspect of nature, and either endeavours to extend the anthropomorphic view over the whole of nature--which is the tendency of theology; or to give the same exclusive predominance to the physical view--which is the tendency of science; or adopts a middle course, and taking from the anthropomorphic view its tendency to personify, and from the physical view its tendency to exclude volition and affection, ends in what M. Comte calls the "metaphysical" state--"metaphysical," in M. Comte's writings, being a general term of abuse for anything he does not like. What is true of the individual is, _mutatis mutandis_, true of the intellectual development of the species. It is absurd to say of men in a state of primitive savagery, that all their conceptions are in a theological state. Nine-tenths of them are eminently realistic, and as "positive" as ignorance and narrowness can make them. It no more occurs to a savage than it does to a child, to ask the why of the daily and ordinary occurrences which form the greater part of his mental life. But in regard to the more striking, or out-of-the-way, events, which force him to speculate, he is highly anthropomorphic; and, as compared with a child, his anthropomorphism is complicated by the intense impression which the death of his own kind makes upon him, as indeed it well may. The warrior, full of ferocious energy, perhaps the despotic chief of his tribe, is suddenly struck down. A child may insult the man a moment before so awful; a fly rests, undisturbed, on the lips from which undisputed command issued. And yet the bodily aspect of the man seems hardly more altered than when he slept, and, sleeping, seemed to himself to leave his body and wander through dreamland. What then if that something, which is the essence of the man, has really been made to wander by the violence done to it, and is unable, or has forgotten, to come back to its shell? Will it not retain somewhat of the powers it possessed during life? May it not help us if it be pleased, or (as seems to be by far the more general impression) hurt us if it be angered? Will it not be well to do towards it those things which would have soothed the man and put him in good humour during his life? It is impossible to study trustworthy accounts of savage thought without seeing, that some such train of ideas as this, lies at the bottom of their speculative beliefs. There are savages without God, in any proper sense of the word, but none without ghosts. And the Fetishism, Ancestor-worship, Hero-worship, and Demonology of primitive savages, are all, I believe, different manners of expression of their belief in ghosts, and of the anthropomorphic interpretation of out-of-the-way events, which is its concomitant. Witchcraft and sorcery are the practical expressions of these beliefs; and they stand in the same relation to religious worship as the simple anthropomorphism of children, or savages, does to theology. In the progress of the species from savagery to advanced civilization, anthropomorphism grows into theology, while physicism (if I may so call it) develops into science; but the development of the two is contemporaneous, not successive. For each, there long exists an assured province which is not invaded by the other; while, between the two, lies a debateable land, ruled by a sort of bastards, who owe their complexion to physicism and their substance to anthropomorphism, and are M. Comte's particular aversions--metaphysical entities. But, as the ages lengthen, the borders of Physicism increase. The territories of the bastards are all annexed to science; and even Theology, in her purer forms, has ceased to be anthropomorphic, however she may talk. Anthropomorphism has taken stand in its last fortress--man himself. But science closely invests the walls; and Philosophers gird themselves for battle upon the last and greatest of all speculative problems--Does human nature possess any free, volitional, or truly anthropomorphic element, or is it only the cunningest of all Nature's clocks? Some, among whom I count myself, think that the battle will for ever remain a drawn one, and that, for all practical purposes, this result is as good as anthropomorphism winning the day. The classification of the sciences, which, in the eyes of M. Comte's adherents, constitutes his second great claim to the dignity of a scientific philosopher, appears to me to be open to just the same objections as the law of the three states. It is inconsistent in itself, and it is inconsistent with fact. Let us consider the main points of this classification successively:-- "Il faut distinguer par rapport à tous les ordres des phénomènes, deux genres de sciences naturelles; les unes abstraites, générales, ont pour objet la découverte des lois qui régissent les diverses classes de phénomènes, en considérant tous les cas qu'on peut concevoir; les autres concrètes, particulières, descriptives, et qu'on désigne quelquefois sous le nom des sciences naturelles proprement dites, consistent dans l'application de ces lois à l'histoire effective des différents êtres existants."[23] The "abstract" sciences are subsequently said to be mathematics, astronomy, physics, chemistry, physiology, and social physics--the titles of the two latter being subsequently changed to biology and sociology. M. Comte exemplifies the distinction between his abstract and his concrete sciences as follows:-- "On pourra d'abord l'apercevoir très-nettement en comparant, d'une part, la physiologie générale, et d'une autre part la zoologie et la botanique proprement dites. Ce sont évidemment, en effet, deux travaux d'un caractère fort distinct, que d'étudier, en général, les lois de la vie, ou de déterminer le mode d'existence de chaque corps vivant, en particulier. _Cette seconde étude, en outre, est nécessairememt fondée sur la première._"--P. 57. All the unreality and mere bookishness of M. Comte's knowledge of physical science comes out in the passage I have italicised. "The special study of living beings is based upon a general study of the laws of life!" What little I know about the matter leads me to think, that, if M. Comte had possessed the slightest practical acquaintance with biological science, he would have turned his phraseology upside down, and have perceived that we can have no knowledge of the general laws of life, except that which is based upon the study of particular living beings. The illustration is surely unluckily chosen; but the language in which these so-called abstract sciences are defined seems to me to be still more open to criticism. With what propriety can astronomy, or physics, or chemistry, or biology, be said to occupy themselves with the consideration of "all conceivable cases" which fall within their respective provinces? Does the astronomer occupy himself with any other system of the universe than that which is visible to him? Does he speculate upon the possible movements of bodies which may attract one another in the inverse proportion of the cube of their distances, say? Does biology, whether "abstract" or "concrete," occupy itself with any other form of life than those which exist, or have existed? And, if the abstract sciences embrace all conceivable cases of the operation of the laws with which they are concerned, would not they, necessarily, embrace the subjects of the concrete sciences, which, inasmuch as they exist, must needs be conceivable? In fact, no such distinction as that which M. Comte draws is tenable. The first stage of his classification breaks by its own weight. But granting M. Comte his six abstract sciences, he proceeds to arrange them according to what he calls their natural order or hierarchy, their places in this hierarchy being determined by the degree of generality and simplicity of the conceptions with which they deal. Mathematics occupies the first, astronomy the second, physics the third, chemistry the fourth, biology the fifth, and sociology the sixth and last place in the series. M. Comte's arguments in favour of this classification are first-- "Sa conformité essentielle avec la co-ordination, en quelque sorte spontanée, qui se trouve en effet implicitement admise par les savants livrés à l'étude des diverse branches de la philosophie naturelle." But I absolutely deny the existence of this conformity. If there is one thing clear about the progress of modern science, it is the tendency to reduce all scientific problems, except those which are purely mathematical, to questions of molecular physics--that is to, say, to the attractions, repulsions, motions, and co-ordination of the ultimate particles of matter. Social phænomena are the result of the interaction of the components of society, or men, with one another and the surrounding universe. But, in the language of physical science, which, by the nature of the case, is materialistic, the actions of men, so far as they are recognisable by science, are the results of molecular changes in the matter of which they are composed; and, in the long run, these must come into the hands of the physicist. _A fortiori_, the phænomena of biology and of chemistry are, in their ultimate analysis, questions of molecular physics. Indeed, the fact is acknowledged by all chemists and biologists who look beyond their immediate occupations. And it is to be observed, that the phænomena of biology are as directly and immediately connected with molecular physics as are those of chemistry. Molar physics, chemistry, and biology are not three successive steps in the ladder of knowledge, as M. Comte would have us believe, but three branches springing from the common stem of molecular physics. As to astronomy, I am at a loss to understand how any one who will give a moment's attention to the nature of the science can fail to see that it consists of two parts: first, of a description of the phænomena, which is as much entitled as descriptive zoology, or botany, is, to the name of natural history; and, secondly, of an explanation of the phænomena, furnished by the laws of a force--gravitation--the study of which is as much a part of physics, as is that of heat, or electricity. It would be just as reasonable to make the study of the heat of the sun a science preliminary to the rest of thermotics, as to place the study of the attraction of the bodies, which compose the universe in general, before that of the particular terrestrial bodies, which alone we can experimentally know. Astronomy, in fact, owes its perfection to the circumstance that it is the only branch of natural history, the phænomena of which are largely expressible by mathematical conceptions, and which can be, to a great extent, explained by the application of very simple physical laws. With regard to mathematics, it is to be observed, in the first place, that M. Comte mixes up under that head the pure relations of space and of quantity, which are properly included under the name, with rational mechanics and statics, which are mathematical developments of the most general conceptions of physics, namely, the notions of force and of motion. Relegating these to their proper place in physics, we have left pure mathematics, which can stand neither at the head, nor at the tail, of any hierarchy of the sciences, since, like logic, it is equally related to all; though the enormous practical difficulty of applying mathematics to the more complex phænomena of nature removes them, for the present, out of its sphere. On this subject of mathematics, again, M. Comte indulges in assertions which can only be accounted for by his total ignorance of physical science practically. As for example:-- "C'est donc par l'étude des mathématiques, _et seulement par elle_, que l'on peut se faire une idée juste et approfondie de ce que c'est qu'une _science_. C'est là _uniquement_ qu'on doit chercher à connaître avec précision _la méthode générale que l'esprit humain emploie constamment dans toutes ses recherches positives_, parce que nulle part ailleurs les questions ne sont résolues d'une manière aussi complète et les déductions prolongées aussi loin avec une sévérité rigoureuse. C'est là également que notre entendement a donné les plus grandes preuves de sa force, parce que les ideés qu'il y considère sont du plus haut degré d'abstraction possible dans l'ordre positif. _Toute éducation scientifique qui ne commence point par une telle étude pèche donc nécessairement par sa base._"[24] That is to say, the only study which can confer "a just and comprehensive idea of what is meant by science," and, at the same time, furnish an exact conception of the general method of scientific investigation, is that which knows nothing of observation, nothing of experiment, nothing of induction, nothing of causation! And education, the whole secret of which consists in proceeding from the easy to the difficult, the concrete to the abstract, ought to be turned the other way, and pass from the abstract to the concrete. M. Comte puts a second argument in favour of his hierarchy of the sciences thus:-- "Un second caractère très-essentiel de notre classification, c'est d'être nécessairement conforme à l'ordre effectif du développement de la philosophie naturelle. C'est ce que vérifie tout ce qu'on sait de l'histoire des sciences."[25] But Mr. Spencer has so thoroughly and completely demonstrated the absence of any correspondence between the historical development of the sciences, and their position in the Comtean hierarchy, in his essay on the "Genesis of Science," that I shall not waste time in repeating his refutation. A third proposition in support of the Comtean classification of the sciences stands as follows:-- "En troisième lieu cette classification présente la propriété très-remarquable de marquer exactement la perfection relative des différentes sciences, laquelle consiste essentiellement dans le degré de précision des connaissances et dans leur co-ordination plus ou moins intime."[26] I am quite unable to understand the distinction which M. Comte endeavours to draw in this passage in spite of his amplifications further on. Every science must consist of precise knowledge, and that knowledge must be co-ordinated into general proportions, or it is not science. When M. Comte, in exemplification of the statement I have cited, says that "les phénomènes organiques ne comportent qu'une étude à la fois moins exacte et moins systématique que les phénomènes des corps bruts," I am at a loss to comprehend what he means. If I affirm that "when a motor nerve is irritated, the muscle connected with it becomes simultaneously shorter and thicker, without changing its volume," it appears to me that the statement is as precise or exact (and not merely as true) as that of the physicist who should say, that "when a piece of iron is heated, it becomes simultaneously longer and thicker and increases in volume;" nor can I discover any difference, in point of precision, between the statement of the morphological law that "animals which suckle their young have two occipital condyles," and the enunciation of the physical law that "water subjected to electrolysis is replaced by an equal weight of the gases, oxygen and hydrogen." As for anatomical or physiological investigation being less "systematic" than that of the physicist or chemist, the assertion is simply unaccountable. The methods of physical science are everywhere the same in principle, and the physiological investigator who was not "systematic" would, on the whole, break down rather sooner than the inquirer into simpler subjects. Thus M. Comte's classification of the sciences, under all its aspects, appears to me to be a complete failure. It is impossible, in an article which is already too long, to inquire how it may be replaced by a better; and it is the less necessary to do so, as a second edition of Mr. Spencer's remarkable essay on this subject has just been published. After wading through pages of the long-winded confusion and second-hand information of the "Philosophic Positive," at the risk of a _crise cérébrale_--it is as good as a shower-bath to turn to the "Classification of the Sciences," and refresh oneself with Mr. Spencer's profound thought, precise knowledge, and clear language. II. The second proposition to which I have committed myself, in the paper to which I have been obliged to refer so often, is, that the "Positive Philosophy" contains "a great deal which is as thoroughly antagonistic to the very essence of science as is anything in ultramontane Catholicism." What I refer to in these words, is, on the one hand, the dogmatism and narrowness which so often mark M. Comte's discussion of doctrines which he does not like, and reduce his expressions of opinion to mere passionate puerilities; as, for example, when he is arguing against the assumption of an ether, or when he is talking (I cannot call it arguing) against psychology, or political economy. On the other hand, I allude to the spirit of meddling systematization and regulation which animates even the "Philosophic Positive," and breaks out, in the latter volumes of that work, into no uncertain foreshadowing of the anti-scientific monstrosities of Comte's later writings. Those who try to draw a line of demarcation between the spirit of the "Philosophic Positive," and that of the "Politique" and its successors, (if I may express an opinion from fragmentary knowledge of these last,) must have overlooked, or forgotten, what Comte himself labours to show, and indeed succeeds in proving, in the "Appendice Général" of the "Politique Positive." "Dès mon début," he writes, "je tentai de fonder le nouveau pouvoir spirituel que j'institue aujourd'hui." "Ma politique, loin d'être aucunement opposée à ma philosophie, en constitue tellement la suite naturelle que celle-ci fut directement instituée pour servir de base à celle-là, comme le prouve cet appendice."[27] This is quite true. In the remarkable essay entitled "Considérations sur le Pouvoir spirituel," published in March 1826, Comte advocates the establishment of a "modern spiritual power," which, he anticipates, may exercise an even greater influence over temporal affairs, than did the Catholic clergy, at the height of their vigour and independence, in the twelfth century. This spiritual power is, in fact, to govern opinion, and to have the supreme control over education, in each nation of the West; and the spiritual powers of the several European peoples are to be associated together and placed under a common direction or "souveraineté spirituelle." A system of "Catholicism _minus_ Christianity" was therefore completely organized in Comte's mind, four years before the first volume of the "Philosophie Positive" was written; and, naturally, the papal spirit shows itself in that work, not only in the ways I have already mentioned, but, notably, in the attack on liberty of conscience which breaks out in the fourth volume:-- "Il n'y a point de liberté de conscience en astronomie, en physique, en chimie, en physiologie même, en ce sens que chacun trouverait absurde de ne pas croire de confiance aux principes établis dans les sciences par les hommes compétents." "Nothing in ultramontane Catholicism" can, in my judgment, be more completely sacerdotal, more entirely anti-scientific, than this dictum. All the great steps in the advancement of science have been made by just those men who have not hesitated to doubt the "principles established in the sciences by competent persons;" and the great teaching of science--the great use of it as an instrument of mental discipline--is its constant inculcation of the maxim, that the sole ground on which any statement has a right to be believed is the impossibility of refuting it. Thus, without travelling beyond the limits of the "Philosophie Positive," we find its author contemplating the establishment of a system of society, in which an organized spiritual power shall over-ride and direct the temporal power, as completely as the Innocents and Gregorys tried to govern Europe in the middle ages; and repudiating the exercise of liberty of conscience against the "_hommes compétents_", of whom, by the assumption, the new priesthood would be composed. Was Mr. Congreve as forgetful of this, as he seems to have been of some other parts of the "Philosophie Positive," when he wrote, that "in any limited, careful use of the term, no candid man could say that the Positive Philosophy contained a great deal as thoroughly antagonistic to [the very essence of[28]] science as Catholicism"? M. Comte, it will have been observed, desires to retain the whole of Catholic organization; and the logical practical result of this part of his doctrine would be the establishment of something corresponding with that eminently Catholic, but admittedly anti-scientific, institution--the Holy Office. I hope I have said enough to show that I wrote the few lines I devoted to M. Comte and his philosophy, neither unguardedly, nor ignorantly, still less maliciously. I shall be sorry if what I have now added, in my own justification, should lead any to suppose that I think M. Comte's works worthless; or that I do not heartily respect, and sympathise with, those who have been impelled by him to think deeply upon social problems, and to strive nobly for social regeneration. It is the virtue of that impulse, I believe, which will save the name and fame of Auguste Comte from oblivion. As for his philosophy, I part with it by quoting his own words, reported to me by a quondam Comtist, now an eminent member of the Institute of France, M. Charles Robin:-- "La Philosophie est une tentative incessante de l'esprit humain pour arriver au repos: mais elle se trouve incessamment aussi dérangée par les progrès continus de la science. De là vient pour le philosophe l'obligation de refaire chaque soir la synthèse de ses conceptions; et un jour viendra où l'homme raisonnable ne fera plus d'autre prière du soir." FOOTNOTES: [13] I am glad to observe that Mr. Congreve, in the criticism with which he has favoured me in the number of the _Fortnightly Review_ for April 1869, does not venture to challenge the justice of the claim I make for Hume. He merely suggests that I have been wanting in candour in not mentioning Comte's high opinion of Hume. After mature reflection I am unable to discern my fault. If I had suggested that Comte had borrowed from Hume without acknowledgment; or if, instead of trying to express my own sense of Hume's merits with the modesty which becomes a writer who has no authority in matters of philosophy, I had affirmed that no one had properly appreciated him, Mr. Congreve's remarks would apply: but as I did neither of these things, they appear to me to be irrelevant, if not unjustifiable. And even had it occurred to me to quote M. Comte's expressions about Hume, I do not know that I should have cited them, inasmuch as, on his own showing, M. Comte occasionally speaks very decidedly touching writers of whose works he has not read a line. Thus, in Tome VI. of the "Philosophie Positive," p. 619, M. Comte writes: "Le plus grand des métaphysiciens modernes, l'illustre Kant, a noblement mérité une éternelle admiration en tentant, le premier, d'échapper directement a l'absolu philosophique par sa célèbre conception de la double réalité, à la fois objective et subjective, qui indique un si juste sentiment de la saine philosophie." But in the "Préface Personnelle" in the same volume, p. 35, M. Comte tells us:--"Je n'ai jamais lu, en aucune langue, ni Vico, _ni Kant_, ni Herder, ni Hegel, &c.; je ne connais leurs divers ouvrages que d'après quelques relations indirectes et certains extraits fort insuffisants." Who knows but that the "&c." may include Hume? And in that case what is the value of M. Comte's praise of him? [14] Now and always I quote the second edition, by Littré. [15] "Philosophie Positive," ii. p. 440. [16] "Le brillant mais superficiel Cuvier."--_Philosophie Positive_, vi. p. 383. [17] "Philosophie Positive," iii. p. 369. [18] Ibid. p. 387. [19] Hear the late Dr. Whewell, who calls Comte "a shallow pretender," so far as all the modern sciences, except astronomy, are concerned; and tells us that "his pretensions to discoveries are, as Sir John Herschel has shown, absurdly fallacious."--"Comte and Positivism," _Macmillan's Magazine_, March 1866. [20] "Philosophie Positive," i. pp. 8, 9. [21] "Philosophie Positive," iii. p. 188. [22] The word "positive" is in every way objectionable. In one sense it suggests that mental quality which was undoubtedly largely developed in M. Comte, but can best be dispensed with in a philosopher; in another, it is unfortunate in its application to a system which starts with enormous negations; in its third, and specially philosophical sense, as implying a system of thought which assumes nothing beyond the content of observed facts, it implies that which never did exist, and never will. [23] "Philosophie Positive," i. p. 56. [24] "Philosophie Positive," i. p. 99. [25] Ibid., i. p. 77. [26] "Philosophie Positive," i. p. 78. [27] Loc. cit., Préface Spéciale, pp. i. ii. [28] Mr. Congreve leaves out these important words, which show that I refer to the spirit, and not to the details of science. IX. ON A PIECE OF CHALK. A LECTURE TO WORKING MEN. If a well were to be sunk at our feet in the midst of the city of Norwich, the diggers would very soon find themselves at work in that white substance almost too soft to be called rock, with which we are all familiar as "chalk." Not only here, but over the whole county of Norfolk, the well-sinker might carry his shaft down many hundred feet without coming to the end of the chalk; and, on the sea-coast, where the waves have pared away the face of the land which breasts them, the scarped faces of the high cliffs are often wholly formed of the same material. Northward, the chalk may be followed as far as Yorkshire; on the south coast it appears abruptly in the picturesque western bays of Dorset, and breaks into the Needles of the Isle of Wight; while on the shores of Kent it supplies that long line of white cliffs to which England owes her name of Albion. Were the thin soil which covers it all washed away, a curved band of white chalk, here broader, and there narrower, might be followed diagonally across England from Lulworth in Dorset, to Flamborough Head in Yorkshire--a distance of over 280 miles as the crow flies. From this band to the North Sea, on the east, and the Channel, on the south, the chalk is largely hidden by other deposits; but, except in the Weald of Kent and Sussex, it enters into the very foundation of all the south-eastern counties. Attaining, as it does in some places, a thickness of more than a thousand feet, the English chalk must be admitted to be a mass of considerable magnitude. Nevertheless, it covers but an insignificant portion of the whole area occupied by the chalk formation of the globe, which has precisely the same general characters as ours, and is found in detached patches, some less, and others more extensive, than the English. Chalk occurs in north-west Ireland; it stretches over a large part of France,--the chalk which underlies Paris being, in fact, a continuation of that of the London basin; it runs through Denmark and Central Europe, and extends southward to North Africa; while, eastward, it appears in the Crimea and in Syria, and may be traced as far as the shores of the Sea of Aral, in Central Asia. If all the points at which true chalk occurs were circumscribed, they would lie within an irregular oval about 3,000 miles in long diameter--the area of which would be as great as that of Europe, and would many times exceed that of the largest existing inland sea--the Mediterranean. Thus the chalk is no unimportant element in the masonry of the earth's crust, and it impresses a peculiar stamp, varying with the conditions to which it is exposed, on the scenery of the districts in which it occurs. The undulating downs and rounded coombs, covered with sweet-grassed turf, of our inland chalk country, have a peacefully domestic and mutton-suggesting prettiness, but can hardly be called either grand or beautiful. But, on our southern coasts, the wall-sided cliffs, many hundred feet high, with vast needles and pinnacles standing out in the sea, sharp and solitary enough to serve as perches for the wary cormorant, confer a wonderful beauty and grandeur upon the chalk headlands. And, in the East, chalk has its share in the formation of some of the most venerable of mountain ranges, such as the Lebanon. What is this wide-spread component of the surface of the earth? and whence did it come? You may think this no very hopeful inquiry. You may not unnaturally suppose that the attempt to solve such problems as these can lead to no result, save that of entangling the inquirer in vague speculations, incapable of refutation and of verification. If such were really the case, I should have selected some other subject than a "piece of chalk" for my discourse. But, in truth, after much deliberation, I have been unable to think of any topic which would so well enable me to lead you to see how solid is the foundation upon which some of the most startling conclusions of physical science rest. A great chapter of the history of the world is written in the chalk. Few passages in the history of man can be supported by such an overwhelming mass of direct and indirect evidence as that which testifies to the truth of the fragment of the history of the globe, which I hope to enable you to read, with your own eyes, to-night. Let me add, that few chapters of human history have a more profound significance for ourselves. I weigh my words well when I assert, that the man who should know the true history of the bit of chalk which every carpenter carries about in his breeches-pocket, though ignorant of all other history, is likely, if he will think his knowledge out to its ultimate results, to have a truer, and therefore a better, conception of this wonderful universe, and of man's relation to it, than the most learned student who is deep-read in the records of humanity and ignorant of those of Nature. The language of the chalk is not hard to learn, not nearly so hard as Latin, if you only want to get at the broad features of the story it has to tell; and I propose that we now set to work to spell that story out together. We all know that if we "burn" chalk the result is quicklime. Chalk, in fact, is a compound of carbonic acid gas and lime, and when you make it very hot the carbonic acid flies away and the lime is left. By this method of procedure we see the lime, but we do not see the carbonic acid. If, on the other hand, you were to powder a little chalk, and drop it into a good deal of strong vinegar, there would be a great bubbling and fizzing, and, finally, a clear liquid, in which no sign of chalk would appear. Here you see the carbonic acid in the bubbles; the lime, dissolved in the vinegar, vanishes from sight. There are a great many other ways of showing that chalk is essentially nothing but carbonic acid and quicklime. Chemists enunciate the result of all the experiments which prove this, by stating that chalk is almost wholly composed of "carbonate of lime." It is desirable for us to start from the knowledge of this fact, though it may not seem to help us very far towards what we seek. For carbonate of lime is a widely-spread substance, and is met with under very various conditions. All sorts of limestones are composed of more or less pure carbonate of lime. The crust which is often deposited by waters which have drained through limestone rocks, in the form of what are called stalagmites and stalactites, is carbonate of lime. Or, to take a more familiar example, the fur on the inside of a tea-kettle is carbonate of lime; and, for anything chemistry tells us to the contrary, the chalk might be a kind of gigantic fur upon the bottom of the earth-kettle, which is kept pretty hot below. Let us try another method of making the chalk tell us its own history. To the unassisted eye chalk looks simply like a very loose and open kind of stone. But it is possible to grind a slice of chalk down so thin that you can see through it--until it is thin enough, in fact, to be examined with any magnifying power that may be thought desirable. A thin slice of the fur of a kettle might be made in the same way. If it were examined microscopically, it would show itself to be a more or less distinctly laminated mineral substance, and nothing more. But the slice of chalk presents a totally different appearance when placed under the microscope. The general mass of it is made up of very minute granules; but imbedded in this matrix, are innumerable bodies, some smaller and some larger, but, on a rough average, not more than a hundredth of an inch in diameter, having a well-defined shape and structure. A cubic inch of some specimens of chalk may contain hundreds of thousands of these bodies, compacted together with incalculable millions of the granules. The examination of a transparent slice gives a good notion of the manner in which the components of the chalk are arranged, and of their relative proportions. But, by rubbing up some chalk with a brush in water and then pouring off the milky fluid, so as to obtain sediments of different degrees of fineness, the granules and the minute rounded bodies may be pretty well separated from one another, and submitted to microscopic examination, either as opaque or as transparent objects. By combining the views obtained in these various methods, each of the rounded bodies may be proved to be a beautifully-constructed calcareous fabric, made up of a number of chambers, communicating freely with one another. The chambered bodies are of various forms. One of the commonest is something like a badly-grown raspberry, being formed of a number of nearly globular chambers of different sizes congregated together. It is called _Globigerina_, and some specimens of chalk consist of little else than _Globigerinæ_ and granules. Let us fix our attention upon the _Globigerina_. It is the spoor of the game we are tracking. If we can learn what it is and what are the conditions of its existence, we shall see our way to the origin and past history of the chalk. A suggestion which may naturally enough present itself is, that these curious bodies are the result of some process of aggregation which has taken place in the carbonate of lime; that, just as in winter, the rime on our windows simulates the most delicate and elegantly arborescent foliage--proving that the mere mineral water may, under certain conditions, assume the outward form of organic bodies--so this mineral substance, carbonate of lime, hidden away in the bowels of the earth, has taken the shape of these chambered bodies. I am not raising a merely fanciful and unreal objection. Very learned men, in former days, have even entertained the notion that all the formed things found in rocks are of this nature; and if no such conception is at present held to be admissible, it is because long and varied experience has now shown that mineral matter never does assume the form and structure we find in fossils. If any one were to try to persuade you that an oyster-shell (which is also chiefly composed of carbonate of lime) had crystallized out of sea-water, I suppose you would laugh at the absurdity. Your laughter would be justified by the fact that all experience tends to show that oyster-shells are formed by the agency of oysters, and in no other way. And if there were no better reasons, we should be justified, on like grounds, in believing that _Globigerina_ is not the product of anything but vital activity. Happily, however, better evidence in proof of the organic nature of the _Globigerinæ_ than that of analogy is forthcoming. It so happens that calcareous skeletons, exactly similar to the _Globigerinæ_ of the chalk, are being formed, at the present moment, by minute living creatures, which flourish in multitudes, literally more numerous than the sands of the sea-shore, over a large extent of that part of the earth's surface which is covered by the ocean. The history of the discovery of these living _Globigerinæ_, and of the part which they play in rock-building, is singular enough. It is a discovery which, like others of no less scientific importance, has arisen, incidentally, out of work devoted to very different and exceedingly practical interests. When men first took to the sea, they speedily learned to look out for shoals and rocks; and the more the burthen of their ships increased, the more imperatively necessary it became for sailors to ascertain with precision the depth of the waters they traversed. Out of this necessity grew the use of the lead and sounding-line; and, ultimately, marine-surveying, which is the recording of the form of coasts and of the depth of the sea, as ascertained by the sounding-lead, upon charts. At the same time, it became desirable to ascertain and to indicate the nature of the sea-bottom, since this circumstance greatly affects its goodness as holding ground for anchors. Some ingenious tar, whose name deserves a better fate than the oblivion into which it has fallen, attained this object by "arming" the bottom of the lead with a lump of grease, to which more or less of the sand or mud, or broken shells, as the case might be, adhered, and was brought to the surface. But, however well adapted such an apparatus might be for rough nautical purposes, scientific accuracy could not be expected from the armed lead, and to remedy its defects (especially when applied to sounding in great depths) Lieut. Brooke, of the American Navy, some years ago invented a most ingenious machine, by which a considerable portion of the superficial layer of the sea-bottom can be scooped out and brought up, from any depth to which the lead descends. In 1853, Lieut. Brooke obtained mud from the bottom of the North Atlantic, between Newfoundland and the Azores, at a depth of more than 10,000 feet, or two miles, by the help of this sounding apparatus. The specimens were sent for examination to Ehrenberg of Berlin, and to Bailey of West Point, and those able microscopists found that this deep-sea mud was almost entirely composed of the skeletons of living organisms--the greater proportion of these being just like the _Globigerinæ_ already known to occur in the chalk. Thus far, the work had been carried on simply in the interests of science, but Lieut. Brooke's method of sounding acquired a high commercial value, when the enterprise of laying down the telegraph-cable between this country and the United States was undertaken. For it became a matter of immense importance to know, not only the depth of the sea over the whole line along which the cable was to be laid, but the exact nature of the bottom, so as to guard against chances of cutting or fraying the strands of that costly rope. The Admiralty consequently ordered Captain Dayman, an old friend and shipmate of mine, to ascertain the depth over the whole line of the cable, and to bring back specimens of the bottom. In former days, such a command as this might have sounded very much like one of the impossible things which the young prince in the Fairy Tales is ordered to do before he can obtain the hand of the Princess. However, in the months of June and July 1857, my friend performed the task assigned to him with great expedition and precision, without, so far as I know, having met with any reward of that kind. The specimens of Atlantic mud which he procured were sent to me to be examined and reported upon.[29] The result of all these operations is, that we know the contours and the nature of the surface-soil covered by the North Atlantic, for a distance of 1,700 miles from east to west, as well as we know that of any part of the dry land. It is a prodigious plain--one of the widest and most even plains in the world. If the sea were drained off, you might drive a wagon all the way from Valentia, on the west coast of Ireland, to Trinity Bay, in Newfoundland. And, except upon one sharp incline about 200 miles from Valentia, I am not quite sure that it would even be necessary to put the skid on, so gentle are the ascents and descents upon that long route. From Valentia the road would lie down hill for about 200 miles to the point at which the bottom is now covered by 1,700 fathoms of sea-water. Then would come the central plain, more than a thousand miles wide, the inequalities of the surface of which would be hardly perceptible, though the depth of water upon it now varies from 10,000 to 15,000 feet; and there are places in which Mont Blanc might be sunk without showing its peak above water. Beyond this, the ascent on the American side commences, and gradually leads, for about 300 miles, to the Newfoundland shore. Almost the whole of the bottom of this central plain (which extends for many hundred miles in a north and south direction) is covered by a fine mud, which, when brought to the surface, dries into a greyish-white friable substance. You can write with this on a blackboard, if you are so inclined; and, to the eye, it is quite like very soft, greyish chalk. Examined chemically, it proves to be composed almost wholly of carbonate of lime; and if you make a section of it, in the same way as that of the piece of chalk was made, and view it with the microscope, it presents innumerable _Globigerinæ_, embedded in a granular matrix. Thus this deep-sea mud is substantially chalk. I say substantially, because there are a good many minor differences: but as these have no bearing on the question immediately before us,--which is the nature of the _Globigerinæ_ of the chalk,--it is unnecessary to speak of them. _Globigerinæ_ of every size, from the smallest to the largest, are associated together in the Atlantic mud, and the chambers of many are filled by a soft animal matter. This soft substance is, in fact, the remains of the creature to which the _Globigerina_ shell, or rather skeleton, owes its existence--and which is an animal of the simplest imaginable description. It is, in fact, a mere particle of living jelly, without defined parts of any kind--without a mouth, nerves, muscles, or distinct organs, and only manifesting its vitality to ordinary observation by thrusting out and retracting from all parts of its surface, long filamentous processes, which serve for arms and legs. Yet this amorphous particle, devoid of everything which, in the higher animals, we call organs, is capable of feeding, growing, and multiplying; of separating from the ocean the small proportion of carbonate of lime which is dissolved in sea-water; and of building up that substance into a skeleton for itself, according to a pattern which can be imitated by no other known agency. The notion that animals can live and flourish in the sea, at the vast depths from which apparently living _Globigerinæ_ have been brought up, does not agree very well with our usual conceptions respecting the conditions of animal life; and it is not so absolutely impossible as it might at first sight appear to be, that the _Globigerinæ_ of the Atlantic sea-bottom do not live and die where they are found. As I have mentioned, the soundings from the great Atlantic plain are almost entirely made up of _Globigerinæ_, with the granules which have been mentioned, and some few other calcareous shells; but a small percentage of the chalky mud--perhaps at most some five per cent. of it--is of a different nature, and consists of shells and skeletons composed of silex, or pure flint. These silicious bodies belong partly to the lowly vegetable organisms which are called _Diatomaceæ_, and partly to the minute, and extremely simple, animals, termed _Radiolaria_. It is quite certain that these creatures do not live at the bottom of the ocean, but at its surface--where they may be obtained in prodigious numbers by the use of a properly constructed net. Hence it follows that these silicious organisms, though they are not heavier than the lightest dust, must have fallen, in some cases, through fifteen thousand feet of water, before they reached their final resting-place on the ocean floor. And, considering how large a surface these bodies expose in proportion to their weight, it is probable that they occupy a great length of time in making their burial journey from the surface of the Atlantic to the bottom. But if the _Radiolaria_ and Diatoms are thus rained upon the bottom of the sea, from the superficial layer of its waters in which they pass their lives, it is obviously possible that the _Globigerinæ_ may be similarly derived; and if they were so, it would be much more easy to understand how they obtain their supply of food than it is at present. Nevertheless, the positive and negative evidence all points the other way. The skeletons of the full-grown, deep-sea _Globigerinæ_ are so remarkably solid and heavy in proportion to their surface as to seem little fitted for floating; and, as a matter of fact, they are not to be found along with the Diatoms and _Radiolaria_, in the uppermost stratum of the open ocean. It has been observed, again, that the abundance of _Globigerinæ_, in proportion to other organisms of like kind, increases with the depth of the sea; and that deep-water _Globigerinæ_ are larger than those which live in shallower parts of the sea; and such facts negative the supposition that these organisms have been swept by currents from the shallows into the deeps of the Atlantic. It therefore seems to be hardly doubtful that these wonderful creatures live and die at the depths in which they are found.[30] However, the important points for us are, that the living _Globigerinæ_ are exclusively marine animals, the skeletons of which abound at the bottom of deep seas; and that there is not a shadow of reason for believing that the habits of the _Globigerinæ_ of the chalk differed from those of the existing species. But if this be true, there is no escaping the conclusion that the chalk itself is the dried mud of an ancient deep sea. In working over the soundings collected by Captain Dayman, I was surprised to find that many of what I have called the "granules" of that mud, were not, as one might have been tempted to think at first, the mere powder and waste of _Globigerinæ_, but that they had a definite form and size, I termed these bodies "_coccoliths_," and doubted their organic nature. Dr. Wallich verified my observation, and added the interesting discovery that, not unfrequently, bodies similar to these "coccoliths" were aggregated together into spheroids, which he termed "_coccospheres_." So far as we knew, these bodies, the nature of which is extremely puzzling and problematical, were peculiar to the Atlantic soundings. But, a few years ago, Mr. Sorby, in making a careful examination of the chalk by means of thin sections and otherwise, observed, as Ehrenberg had done before him, that much of its granular basis possesses a definite form. Comparing these formed particles with those in the Atlantic soundings, he found the two to be identical; and thus proved that the chalk, like the soundings, contains these mysterious coccoliths and coccospheres. Here was a further and a most interesting confirmation, from internal evidence, of the essential identity of the chalk with modern deep-sea mud. _Globigerinæ_, coccoliths, and coccospheres are found as the chief constituents of both, and testify to the general similarity of the conditions under which both have been formed.[31] The evidence furnished by the hewing, facing, and superposition of the stones of the Pyramids, that these structures were built by men, has no greater weight than the evidence that the chalk was built by _Globigerinæ_; and the belief that those ancient pyramid-builders were terrestrial and air-breathing creatures like ourselves, is not better based than the conviction that the chalk-makers lived in the sea. But as our belief in the building of the Pyramids by men is not only grounded on the internal evidence afforded by these structures, but gathers strength from multitudinous collateral proofs, and is clinched by the total absence of any reason for a contrary belief; so the evidence drawn from the _Globigerinæ_ that the chalk is an ancient sea-bottom, is fortified by innumerable independent lines of evidence; and our belief in the truth of the conclusion to which all positive testimony tends, receives the like negative justification from the fact that no other hypothesis has a shadow of foundation. It may be worth while briefly to consider a few of these collateral proofs that the chalk was deposited at the bottom of the sea. The great mass of the chalk is composed, as we have seen, of the skeletons of _Globigerinæ_, and other simple organisms, imbedded in granular matter. Here and there, however, this hardened mud of the ancient sea reveals the remains of higher animals which have lived and died, and left their hard parts in the mud, just as the oysters die and leave their shells behind them, in the mud of the present seas. There are, at the present day, certain groups of animals which are never found in fresh waters, being unable to live anywhere but in the sea. Such are the corals; those corallines which are called _Polyzoa_; those creatures which fabricate the lamp-shells, and are called _Brachiopoda_; the pearly _Nautilus_, and all animals allied to it; and all the forms of sea-urchins and star-fishes. Not only are all these creatures confined to salt water at the present day; but, so far as our records of the past go, the conditions of their existence have been the same: hence, their occurrence in any deposit is as strong evidence as can be obtained, that that deposit was formed in the sea. Now the remains of animals of all the kinds which have been enumerated, occur in the chalk, in greater or less abundance; while not one of those forms of shell-fish which are characteristic of fresh water has yet been observed in it. When we consider that the remains of more than three thousand distinct species of aquatic animals have been discovered among the fossils of the chalk, that the great majority of them are of such forms as are now met with only in the sea, and that there is no reason to believe that any one of them inhabited fresh water--the collateral evidence that the chalk represents an ancient sea-bottom acquires as great force as the proof derived from the nature of the chalk itself. I think you will now allow that I did not overstate my case when I asserted that we have as strong grounds for believing that all the vast area of dry land, at present occupied by the chalk, was once at the bottom of the sea, as we have for any matter of history whatever; while there is no justification for any other belief. No less certain is it that the time during which the countries we now call south-east England, France, Germany, Poland, Russia, Egypt, Arabia, Syria, were more or less completely covered by a deep sea, was of considerable duration. We have already seen that the chalk is, in places, more than a thousand feet thick. I think you will agree with me, that it must have taken some time for the skeletons of animalcules of a hundredth of an inch in diameter to heap up such a mass as that. I have said that throughout the thickness of the chalk the remains of other animals are scattered. These remains are often in the most exquisite state of preservation. The valves of the shell-fishes are commonly adherent; the long spines of some of the sea-urchins, which would be detached by the smallest jar, often remain in their places. In a word, it is certain that these animals have lived and died when the place which they now occupy was the surface of as much of the chalk as had then been deposited; and that each has been covered up by the layer of _Globigerinæ_ mud, upon which the creatures imbedded a little higher up have, in like manner, lived and died. But some of these remains prove the existence of reptiles of vast size in the chalk sea. These lived their time, and had their ancestors and descendants, which assuredly implies time, reptiles being of slow growth. There is more curious evidence, again, that the process of covering up, or, in other words, the deposit of _Globigerinæ_ skeletons, did not go on very fast. It is demonstrable that an animal of the cretaceous sea might die, that its skeleton might lie uncovered upon the sea-bottom long enough to lose all its outward coverings and appendages by putrefaction; and that, after this had happened, another animal might attach itself to the dead and naked skeleton, might grow to maturity, and might itself die before the calcareous mud had buried the whole. Cases of this kind are admirably described by Sir Charles Lyell. He speaks of the frequency with which geologists find in the chalk a fossilized sea-urchin, to which is attached the lower valve of a _Crania_. This is a kind of shell-fish, with a shell composed of two pieces, of which, as in the oyster, one is fixed and the other free. "The upper valve is almost invariably wanting, though occasionally found in a perfect state of preservation in the white chalk at some distance. In this case, we see clearly that the sea-urchin first lived from youth to age, then died and lost its spines, which were carried away. Then the young _Crania_ adhered to the bared shell, grew and perished in its turn; after which, the upper valve was separated from the lower, before the Echinus became enveloped in chalky mud."[32] A specimen in the Museum of Practical Geology, in London, still further prolongs the period which must have elapsed between the death of the sea-urchin, and its burial by the _Globigerinæ_. For the outward face of the valve of a _Crania_, which is attached to a sea-urchin (_Micraster_), is itself overrun by an incrusting coralline, which spreads thence over more or less of the surface of the sea-urchin. It follows that, after the upper valve of the _Crania_ fell off, the surface of the attached valve must have remained exposed long enough to allow of the growth of the whole coralline, since corallines do not live imbedded in mud. The progress of knowledge may, one day, enable us to deduce from such facts as these the maximum rate at which the chalk can have accumulated, and thus to arrive at the minimum duration of the chalk period. Suppose that the valve of the _Crania_ upon which a coralline has fixed itself in the way just described, is so attached to the sea-urchin that no part of it is more than an inch above the face upon which the sea-urchin rests. Then, as the coralline could not have fixed itself, if the _Crania_ had been covered up with chalk mud, and could not have lived had itself been so covered, it follows, that an inch of chalk mud could not have accumulated within the time between the death and decay of the soft parts of the sea-urchin and the growth of the coralline to the full size which it has attained. If the decay of the soft parts of the sea-urchin; the attachment, growth to maturity, and decay of the _Crania_; and the subsequent attachment and growth of the coralline, took a year (which is a low estimate enough), the accumulation of the inch of chalk must have taken more than a year: and the deposit of a thousand feet of chalk must, consequently, have taken more than twelve thousand years. The foundation of all this calculation is, of course, a knowledge of the length of time the _Crania_ and the coralline needed to attain their full size; and, on this head, precise knowledge is at present wanting. But there are circumstances which tend to show, that nothing like an inch of chalk has accumulated during the life of a _Crania_; and, on any probable estimate of the length of that life, the chalk period must have had a much longer duration than that thus roughly assigned to it. Thus, not only is it certain that the chalk is the mud of an ancient sea-bottom; but it is no less certain, that the chalk sea existed during an extremely long period, though we may not be prepared to give a precise estimate of the length of that period in years. The relative duration is clear, though the absolute duration may not be definable. The attempt to affix any precise date to the period at which the chalk sea began, or ended, its existence, is baffled by difficulties of the same kind. But the relative age of the cretaceous epoch may be determined with as great ease and certainty as the long duration of that epoch. You will have heard of the interesting discoveries recently made, in various parts of Western Europe, of flint implements, obviously worked into shape by human hands, under circumstances which show conclusively that man is a very ancient denizen of these regions. It has been proved that the old populations of Europe, whose existence has been revealed to us in this way, consisted of savages, such as the Esquimaux are now; that, in the country which is now France, they hunted the reindeer, and were familiar with the ways of the mammoth and the bison. The physical geography of France was in those days different from what it is now--the river Somme, for instance, having cut its bed a hundred feet deeper between that time and this; and, it is probable, that the climate was more like that of Canada or Siberia, than that of Western Europe. The existence of these people is forgotten even in the traditions of the oldest historical nations. The name and fame of them had utterly vanished until a few years back; and the amount of physical change which has been effected since their day, renders it more than probable that, venerable as are some of the historical nations, the workers of the chipped flints of Hoxne or of Amiens are to them, as they are to us, in point of antiquity. But, if we assign to these hoar relics of long vanished generations of men the greatest age that can possibly be claimed for them, they are not older than the drift, or boulder clay, which, in comparison with the chalk, is but a very juvenile deposit. You need go no further than your own sea-board for evidence of this fact. At one of the most charming spots on the coast of Norfolk, Cromer, you will see the boulder clay forming a vast mass, which lies upon the chalk, and must consequently have come into existence after it. Huge boulders of chalk are, in fact, included in the clay, and have evidently been brought to the position they now occupy, by the same agency as that which has planted blocks of syenite from Norway side by side with them. The chalk, then, is certainly older than the boulder clay. If you ask how much, I will again take you no further than the same spot upon your own coasts for evidence. I have spoken of the boulder clay and drift as resting upon the chalk. That is not strictly true. Interposed between the chalk and the drift is a comparatively insignificant layer, containing vegetable matter. But that layer tells a wonderful history. It is full of stumps of trees standing as they grew. Fir-trees are there with their cones, and hazel-bushes with their nuts; there stand the stools of oak and yew trees, beeches and alders. Hence this stratum is appropriately called the "forest-bed." It is obvious that the chalk must have been upheaved and converted into dry land, before the timber trees could grow upon it. As the bolls of some of these trees are from two to three feet in diameter, it is no less clear that the dry land thus formed remained in the same condition for long ages. And not only do the remains of stately oaks and well-grown firs testify to the duration of this condition of things, but additional evidence to the same effect is afforded by the abundant remains of elephants, rhinoceroses, hippopotamuses, and other great wild beasts, which it has yielded to the zealous search of such men as the Rev. Mr. Gunn. When you look at such a collection as he has formed, and bethink you that these elephantine bones did veritably carry their owners about, and these great grinders crunch, in the dark woods of which the forest-bed is now the only trace, it is impossible not to feel that they are as good evidence of the lapse of time as the annual rings of the tree-stumps. Thus there is a writing upon the wall of cliffs at Cromer, and whoso runs may read it. It tells us, with an authority which cannot be impeached, that the ancient sea-bed of the chalk sea was raised up, and remained dry land, until it was covered with forest, stocked with the great game whose spoils have rejoiced your geologists. How long it remained in that condition cannot be said; but "the whirligig of time brought its revenges" in those days as in these. That dry land, with the bones and teeth of generations of long-lived elephants, hidden away among the gnarled roots and dry leaves of its ancient trees, sank gradually to the bottom of the icy sea, which covered it with huge masses of drift and boulder clay. Sea-beasts, such as the walrus, now restricted to the extreme north, paddled about where birds had twittered among the topmost twigs of the fir-trees. How long this state of things endured we know not, but at length it came to an end. The upheaved glacial mud hardened into the soil of modern Norfolk. Forests grew once more, the wolf and the beaver replaced the reindeer and the elephant; and at length what we call the history of England dawned. Thus you have, within the limits of your own county, proof that the chalk can justly claim a very much greater antiquity than even the oldest physical traces of mankind. But we may go further and demonstrate, by evidence of the same authority as that which testifies to the existence of the father of men, that the chalk is vastly older than Adam himself. The Book of Genesis informs us that Adam, immediately upon his creation, and before the appearance of Eve, was placed in the Garden of Eden. The problem of the geographical position of Eden has greatly vexed the spirits of the learned in such matters, but there is one point respecting which, so far as I know, no commentator has ever raised a doubt. This is, that of the four rivers which are said to run out of it, Euphrates and Hiddekel are identical with the rivers now known by the names of Euphrates and Tigris. But the whole country in which these mighty rivers take their origin, and through which they run, is composed of rocks which are either of the same age as the chalk, or of later date. So that the chalk must not only have been formed, but, after its formation, the time required for the deposit of these later rocks, and for their upheaval into dry land, must have elapsed, before the smallest brook which feeds the swift stream of "the great river, the river of Babylon," began to flow. Thus, evidence which cannot be rebutted, and which need not be strengthened, though if time permitted I might indefinitely increase its quantity, compels you to believe that the earth, from the time of the chalk to the present day, has been the theatre of a series of changes as vast in their amount, as they were slow in their progress. The area on which we stand has been first sea and then land, for at least four alternations; and has remained in each of these conditions for a period of great length. Nor have these wonderful metamorphoses of sea into land, and of land into sea, been confined to one corner of England. During the chalk period, or "cretaceous epoch," not one of the present great physical features of the globe was in existence. Our great mountain ranges, Pyrenees, Alps, Himalayas, Andes, have all been upheaved since the chalk was deposited, and the cretaceous sea flowed over the sites of Sinai and Ararat. All this is certain, because rocks of cretaceous, or still later, date have shared in the elevatory movements which gave rise to these mountain chains; and may be found perched up, in some cases, many thousand feet high upon their flanks. And evidence of equal cogency demonstrates that, though, in Norfolk, the forest-bed rests directly upon the chalk, yet it does so, not because the period at which the forest grew immediately followed that at which the chalk was formed, but because an immense lapse of time, represented elsewhere by thousands of feet of rock, is not indicated at Cromer. I must ask you to believe that there is no less conclusive proof that a still more prolonged succession of similar changes occurred, before the chalk was deposited. Nor have we any reason to think that the first term in the series of these changes is known. The oldest sea-beds preserved to us are sands, and mud, and pebbles, the wear and tear of rocks which were formed in still older oceans. But, great as is the magnitude of these physical changes of the world, they have been accompanied by a no less striking series of modifications in its living inhabitants. All the great classes of animals, beasts of the field, fowls of the air, creeping things, and things which dwell in the waters, flourished upon the globe long ages before the chalk was deposited. Very few, however, if any, of these ancient forms of animal life were identical with those which now live. Certainly not one of the higher animals was of the same species as any of those now in existence. The beasts of the field, in the days before the chalk, were not our beasts of the field, nor the fowls of the air such as those which the eye of men has seen flying, unless his antiquity dates infinitely further back than we at present surmise. If we could be carried back into those times, we should be as one suddenly set down in Australia before it was colonized. We should see mammals, birds, reptiles, fishes, insects, snails, and the like, clearly recognisable as such, and yet not one of them would be just the same as those with which we are familiar, and many would be extremely different. From that time to the present, the population of the world has undergone slow and gradual, but incessant, changes. There has been no grand catastrophe--no destroyer has swept away the forms of life of one period, and replaced them by a totally new creation; but one species has vanished and another has taken its place; creatures of one type of structure have diminished, those of another have increased, as time has passed on. And thus, while the differences between the living creatures of the time before the chalk and those of the present day appear startling, if placed side by side, we are led from one to the other by the most gradual progress, if we follow the course of Nature through the whole series of those relics of her operations which she has left behind. And it is by the population of the chalk sea that the ancient and the modern inhabitants of the world are most completely connected. The groups which are dying out flourish, side by side, with the groups which are now the dominant forms of life. Thus the chalk contains remains of those strange flying and swimming reptiles, the pterodactyl, the ichthyosaurus, and the plesiosaurus, which are found in no later deposits, but abounded in preceding ages. The chambered shells called ammonites and belemnites, which are so characteristic of the period preceding the cretaceous, in like manner die with it. But, amongst these fading remainders of a previous state of things, are some very modern forms of life, looking like Yankee pedlars among a tribe of Red Indians. Crocodiles of modern type appear; bony fishes, many of them very similar to existing species, almost supplant the forms of fish which predominate in more ancient seas; and many kinds of living shell-fish first become known to us in the chalk. The vegetation acquires a modern aspect. A few living animals are not even distinguishable as species, from those which existed at that remote epoch. The _Globigerina_ of the present day, for example, is not different specifically from that of the chalk; and the same may be said of many other _Foraminifera_. I think it probable that critical and unprejudiced examination will show that more than one species of much higher animals have had a similar longevity; but the only example which I can at present give confidently is the snake's-head lamp-shell (_Terebratulina caput serpentis_), which lives in our English seas and abounded (as _Terebratulina striata_ of authors) in the chalk. The longest line of human ancestry must hide its diminished head before the pedigree of this insignificant shell-fish. We Englishmen are proud to have an ancestor who was present at the Battle of Hastings. The ancestors of _Terebratulina caput serpentis_ may have been present at a battle of _Ichthyosauria_ in that part of the sea which, when the chalk was forming, flowed over the site of Hastings. While all around has changed, this _Terebratulina_ has peacefully propagated its species from generation to generation, and stands to this day, as a living testimony to the continuity of the present with the past history of the globe. Up to this moment I have stated, so far as I know, nothing but well-authenticated facts, and the immediate conclusions which they force upon the mind. But the mind is so constituted that it does not willingly rest in facts and immediate causes, but seeks always after a knowledge of the remoter links in the chain of causation. Taking the many changes of any given spot of the earth's surface, from sea to land and from land to sea, as an established fact, we cannot refrain from asking ourselves how these changes have occurred. And when we have explained them--as they must be explained--by the alternate slow movements of elevation and depression which have affected the crust of the earth, we go still further back, and ask, Why these movements? I am not certain that any one can give you a satisfactory answer to that question. Assuredly I cannot. All that can be said, for certain, is, that such movements are part of the ordinary course of nature, inasmuch as they are going on at the present time. Direct proof may be given, that some parts of the land of the northern hemisphere are at this moment insensibly rising and others insensibly sinking; and there is indirect, but perfectly satisfactory, proof, that an enormous area now covered by the Pacific has been deepened thousands of feet, since the present inhabitants of that sea came into existence. Thus there is not a shadow of a reason for believing that the physical changes of the globe, in past times, have been effected by other than natural causes. Is there any more reason for believing that the concomitant modifications in the forms of the living inhabitants of the globe have been brought about in other ways? Before attempting to answer this question, let us try to form a distinct mental picture of what has happened in some special case. The crocodiles are animals which, as a group, have a very vast antiquity. They abounded ages before the chalk was deposited; they throng the rivers in warm climates, at the present day. There is a difference in the form of the joints of the back-bone, and in some minor particulars, between the crocodiles of the present epoch and those which lived before the chalk; but, in the cretaceous epoch, as I have already mentioned, the crocodiles had assumed the modern type of structure. Notwithstanding this, the crocodiles of the chalk are not identically the same as those which lived in the times called "older tertiary," which succeeded the cretaceous epoch; and the crocodiles of the older tertiaries are not identical with those of the newer tertiaries, nor are these identical with existing forms. I leave open the question whether particular species may have lived on from epoch to epoch. But each epoch has had its peculiar crocodiles; though all, since the chalk, have belonged to the modern type, and differ simply in their proportions, and in such structural particulars as are discernible only to trained eyes. How is the existence of this long succession of different species of crocodiles to be accounted for? Only two suppositions seem to be open to us--Either each species of crocodile has been specially created, or it has arisen out of some pre-existing form by the operation of natural causes. Choose your hypothesis; I have chosen mine. I can find no warranty for believing in the distinct creation of a score of successive species of crocodiles in the course of countless ages of time. Science gives no countenance to such a wild fancy; nor can even the perverse ingenuity of a commentator pretend to discover this sense, in the simple words in which the writer of Genesis records the proceedings of the fifth and sixth days of the Creation. On the other hand, I see no good reason for doubting the necessary alternative, that all these varied species have been evolved from pre-existing crocodilian forms, by the operation of causes as completely a part of the common order of nature, as those which have effected the changes of the inorganic world. Few will venture to affirm that the reasoning which applies to crocodiles loses its force among other animals, or among plants. If one series of species has come into existence by the operation of natural causes, it seems folly to deny that all may have arisen in the same way. A small beginning has led us to a great ending. If I were to put the bit of chalk with which we started into the hot but obscure flame of burning hydrogen, it would presently shine like the sun. It seems to me that this physical metamorphosis is no false image of what has been the result of our subjecting it to a jet of fervent, though nowise brilliant, thought to-night. It has become luminous, and its clear rays, penetrating the abyss of the remote past, have brought within our ken some stages of the evolution of the earth. And in the shifting "without haste, but without rest" of the land and sea, as in the endless variation of the forms assumed by living beings, we have observed nothing but the natural product of the forces originally possessed by the substance of the universe. FOOTNOTES: [29] See Appendix to Captain Dayman's "Deep Sea Soundings in the North Atlantic Ocean, between Ireland and Newfoundland, made in H.M.S. _Cyclops_. Published by order of the Lords Commissioners of the Admiralty, 1858." They have since formed the subject of an elaborate Memoir by Messrs. Parker and Jones, published in the _Philosophical Transactions_ for 1865. [30] During the cruise of H.M.S. _Bull-dog_, commanded by Sir Leopold M'Clintock, in 1860, living star-fish were brought up, clinging to the lowest part of the sounding-line, from a depth of 1,260 fathoms, midway between Cape Farewell, in Greenland, and the Rockall banks. Dr. Wallich ascertained that the sea-bottom at this point consisted of the ordinary _Globigerina_ ooze, and that the stomachs of the star-fishes were full of _Globigerinæ_. This discovery removes all objections to the existence of living _Globigerinæ_ at great depths, which are based upon the supposed difficulty of maintaining animal life under such conditions; and it throws the burden of proof upon those who object to the supposition that the _Globigerinæ_ live and die where they are found. [31] I have recently traced out the development of the "coccoliths" from a diameter of 1/7000th of an inch up to their largest size (which is about 1/1600th), and no longer doubt that they are produced by independent organisms, which, like the _Globigerinæ_, live and die at the bottom of the sea. [32] "Elements of Geology," by Sir Charles Lyell, Bart. F.R.S., p. 23. X. GEOLOGICAL CONTEMPORANEITY AND PERSISTENT TYPES OF LIFE. Merchants occasionally go through a wholesome, though troublesome and not always satisfactory, process which they term "taking stock." After all the excitement of speculation, the pleasure of gain, and the pain of loss, the trader makes up his mind to face facts and to learn the exact quantity and quality of his solid and reliable possessions. The man of science does well sometimes to imitate this procedure; and, forgetting for the time the importance of his own small winnings, to re-examine the common stock in trade, so that he may make sure how far the stock of bullion in the cellar--on the faith of whose existence so much paper has been circulating--is really the solid gold of truth. The Anniversary Meeting of the Geological Society seems to be an occasion well suited for an undertaking of this kind--for an inquiry, in fact, into the nature and value of the present results of palæontological investigation; and the more so, as all those who have paid close attention to the late multitudinous discussions in which palæontology is implicated, must have felt the urgent necessity of some such scrutiny. First in order, as the most definite and unquestionable of all the results of palæontology, must be mentioned the immense extension and impulse given to botany, zoology, and comparative anatomy, by the investigation of fossil remains. Indeed, the mass of biological facts has been so greatly increased, and the range of biological speculation has been so vastly widened, by the researches of the geologist and palæontologist, that it is to be feared there are naturalists in existence who look upon geology as Brindley regarded rivers. "Rivers," said the great engineer, "were made to feed canals;" and geology, some seem to think, was solely created to advance comparative anatomy. Were such a thought justifiable, it could hardly expect to be received with favour by this assembly. But it is not justifiable. Your favourite science has her own great aims independent of all others; and if, notwithstanding her steady devotion to her own progress, she can scatter such rich alms among her sisters, it should be remembered that her charity is of the sort that does not impoverish, but "blesseth him that gives and him that takes." Regard the matter as we will, however, the facts remain. Nearly 40,000 species of animals and plants have been added to the Systema Naturæ by palæontological research. This is a living population equivalent to that of a new continent in mere number; equivalent to that of a new hemisphere, if we take into account the small population of insects as yet found fossil, and the large proportion and peculiar organization of many of the Vertebrata. But, beyond this, it is perhaps not too much to say that, except for the necessity of interpreting palæontological facts, the laws of distribution would have received less careful study; while few comparative anatomists (and those not of the first order) would have been induced by mere love of detail, as such, to study the minutiæ of osteology, were it not that in such minutiæ lie the only keys to the most interesting riddles offered by the extinct animal world. These assuredly are great and solid gains. Surely it is matter for no small congratulation that in half a century (for palæontology, though it dawned earlier, came into full day only with Cuvier) a subordinate branch of biology should have doubled the value and the interest of the whole group of sciences to which it belongs. But this is not all. Allied with geology, palæontology has established two laws of inestimable importance: the first, that one and the same area of the earth's surface has been successively occupied by very different kinds of living beings; the second, that the order of succession established in one locality holds good, approximately, in all. The first of these laws is universal and irreversible; the second is an induction from a vast number of observations, though it may possibly, and even probably, have to admit of exceptions. As a consequence of the second law, it follows that a peculiar relation frequently subsists between series of strata, containing organic remains, in different localities. The series resemble one another, not only in virtue of a general resemblance of the organic remains in the two, but also in virtue of a resemblance in the order and character of the serial succession in each. There is a resemblance of arrangement; so that the separate terms of each series, as well as the whole series, exhibit a correspondence. Succession implies time; the lower members of a series of sedimentary rocks are certainly older than the upper; and when the notion of age was once introduced as the equivalent of succession, it was no wonder that correspondence in succession came to be looked upon as correspondence in age, or "contemporaneity." And, indeed, so long as relative age only is spoken of, correspondence in succession _is_ correspondence in age; it is _relative_ contemporaneity. But it would have been very much better for geology if so loose and ambiguous a word as "contemporaneous" had been excluded from her terminology, and if, in its stead, some term expressing similarity of serial relation, and excluding the notion of time altogether, had been employed to denote correspondence in position in two or more series of strata. In anatomy, where such correspondence of position has constantly to be spoken of, it is denoted by the word "homology" and its derivatives; and for Geology (which after all is only the anatomy and physiology of the earth) it might be well to invent some single word, such as "homotaxis" (similarity of order), in order to express an essentially similar idea. This, however, has not been done, and most probably the inquiry will at once be made--To what end burden science with a new and strange term in place of one old, familiar, and part of our common language? The reply to this question will become obvious as the inquiry into the results of palæontology is pushed further. Those whose business it is to acquaint themselves specially with the works of palæontologists, in fact, will be fully aware that very few, if any, would rest satisfied with such a statement of the conclusions of their branch of biology as that which has just been given. Our standard repertories of palæontology profess to teach us far higher things--to disclose the entire succession of living forms upon the surface of the globe; to tell us of a wholly different distribution of climatic conditions in ancient times; to reveal the character of the first of all living existences; and to trace out the law of progress from them to us. It may not be unprofitable to bestow on these professions a somewhat more critical examination than they have hitherto received, in order to ascertain how far they rest on an irrefragable basis; or whether, after all, it might not be well for palæontologists to learn a little more carefully that scientific "ars artium," the art of saying "I don't know." And to this end let us define somewhat more exactly the extent of these pretensions of palæontology. Every one is aware that Professor Bronn's "Untersuchungen" and Professor Pictet's "Traité de Paléontologie" are works of standard authority, familiarly consulted by every working palæontologist. It is desirable to speak of these excellent books, and of their distinguished authors, with the utmost respect, and in a tone as far as possible removed from carping criticism; indeed, if they are specially cited in this place, it is merely in justification of the assertion that the following propositions, which may be found implicitly, or explicitly, in the works in question, are regarded by the mass of palæontologists and geologists, not only on the Continent but in this country, as expressing some of the best-established results of palæontology. Thus:-- Animals and plants began their existence together, not long after the commencement of the deposition of the sedimentary rocks; and then succeeded one another, in such a manner, that totally distinct faunas and floræ occupied the whole surface of the earth, one after the other, and during distinct epochs of time. A geological formation is the sum of all the strata deposited over the whole surface of the earth during one of these epochs: a geological fauna or flora is the sum of all the species of animals or plants which occupied the whole surface of the globe, during one of these epochs. The population of the earth's surface was at first very similar in all parts, and only from the middle of the Tertiary epoch onwards, began to show a distinct distribution in zones. The constitution of the original population, as well as the numerical proportions of its members, indicates a warmer and, on the whole, somewhat tropical climate, which remained tolerably equable throughout the year. The subsequent distribution of living beings in zones is the result of a gradual lowering of the general temperature, which first began to be felt at the poles. It is not now proposed to inquire whether these doctrines are true or false; but to direct your attention to a much simpler though very essential preliminary question--What is their logical basis? what are the fundamental assumptions upon which they all logically depend? and what is the evidence on which those fundamental propositions demand our assent? These assumptions are two: the first, that the commencement of the geological record is coeval with the commencement of life on the globe; the second, that geological contemporaneity is the same thing as chronological synchrony. Without the first of these assumptions there would of course be no ground for any statement respecting the commencement of life; without the second, all the other statements cited, every one of which implies a knowledge of the state of different parts of the earth at one and the same time, will be no less devoid of demonstration. The first assumption obviously rests entirely on negative evidence. This is, of course, the only evidence that ever can be available to prove the commencement of any series of phænomena; but, at the same time, it must be recollected that the value of negative evidence depends entirely on the amount of positive corroboration it receives. If A.B. wishes to prove an _alibi_, it is of no use for him to get a thousand witnesses simply to swear that they did not see him in such and such a place, unless the witnesses are prepared to prove that they must have seen him had he been there. But the evidence that animal life commenced with the Lingula-flags, _e.g._, would seem to be exactly of this unsatisfactory uncorroborated sort. The Cambrian witnesses simply swear they "haven't seen anybody their way;" upon which the counsel for the other side immediately puts in ten or twelve thousand feet of Devonian sandstones to make oath they never saw a fish or a mollusk, though all the world knows there were plenty in their time. But then it is urged that, though the Devonian rocks in one part of the world exhibit no fossils, in another they do, while the lower Cambrian rocks nowhere exhibit fossils, and hence no living being could have existed in their epoch. To this there are two replies: the first, that the observational basis of the assertion that the lowest rocks are nowhere fossiliferous is an amazingly small one, seeing how very small an area, in comparison to that of the whole world, has yet been fully searched; the second, that the argument is good for nothing unless the unfossiliferous rocks in question were not only _contemporaneous_ in the geological sense, but _synchronous_ in the chronological sense. To use the _alibi_ illustration again. If a man wishes to prove he was in neither of two places, A and B, on a given day, his witnesses for each place must be prepared to answer for the whole day. If they can only prove that he was not at A in the morning, and not at B in the afternoon, the evidence of his absence from both is _nil_, because he might have been at B in the morning and at A in the afternoon. Thus everything depends upon the validity of the second assumption. And we must proceed to inquire what is the real meaning of the word "contemporaneous" as employed by geologists. To this end a concrete example may be taken. The Lias of England and the Lias of Germany, the Cretaceous rocks of Britain and the Cretaceous rocks of Southern India, are termed by geologists "contemporaneous" formations; but whenever any thoughtful geologist is asked whether he means to say that they were deposited synchronously, he says, "No,--only within the same great epoch." And if, in pursuing the inquiry, he is asked what may be the approximate value in time of a "great epoch"--whether it means a hundred years, or a thousand, or a million, or ten million years--his reply is, "I cannot tell." If the further question be put, whether physical geology is in possession of any method by which the actual synchrony (or the reverse) of any two distant deposits can be ascertained, no such method can be heard of; it being admitted by all the best authorities that neither similarity of mineral composition, nor of physical character, nor even direct continuity of stratum, are _absolute_ proofs of the synchronism of even approximated sedimentary strata: while, for distant deposits, there seems to be no kind of physical evidence attainable of a nature competent to decide whether such deposits were formed simultaneously, or whether they possess any given difference of antiquity. To return to an example already given. All competent authorities will probably assent to the proposition that physical geology does not enable us in any way to reply to this question--Were the British Cretaceous rocks deposited at the same time as those of India, or are they a million of years younger or a million of years older? Is palæontology able to succeed where physical geology fails? Standard writers on palæontology, as has been seen, assume that she can. They take it for granted, that deposits containing similar organic remains are synchronous--at any rate in a broad sense; and yet, those who will study the eleventh and twelfth chapters of Sir Henry De la Beche's remarkable "Researches in Theoretical Geology," published now nearly thirty years ago, and will carry out the arguments there most luminously stated, to their logical consequences, may very easily convince themselves that even absolute identity of organic contents is no proof of the synchrony of deposits, while absolute diversity is no proof of difference of date. Sir Henry De la Beche goes even further, and adduces conclusive evidence to show that the different parts of one and the same stratum, having a similar composition throughout, containing the same organic remains, and having similar beds above and below it, may yet differ to any conceivable extent in age. Edward Forbes was in the habit of asserting that the similarity of the organic contents of distant formations was _primâ facie_ evidence, not of their similarity, but of their difference of age; and holding as he did the doctrine of single specific centres, the conclusion was as legitimate as any other; for the two districts must have been occupied by migration from one of the two, or from an intermediate spot, and the chances against exact coincidence of migration and of imbedding are infinite. In point of fact, however, whether the hypothesis of single or of multiple specific centres be adopted, similarity of organic contents cannot possibly afford any proof of the synchrony of the deposits which contain them; on the contrary, it is demonstrably compatible with the lapse of the most prodigious intervals of time, and with interposition of vast changes in the organic and inorganic worlds, between the epochs in which such deposits were formed. On what amount of similarity of their faunæ is the doctrine of the contemporaneity of the European and of the North American Silurians based? In the last edition of Sir Charles Lyell's "Elementary Geology" it is stated, on the authority of a former President of this Society, the late Daniel Sharpe, that between 30 and 40 per cent. of the species of Silurian Mollusca are common to both sides of the Atlantic. By way of due allowance for further discovery, let us double the lesser number and suppose that 60 per cent. of the species are common to the North American and the British Silurians. Sixty per cent. of species in common is, then, proof of contemporaneity. Now suppose that, a million or two of years hence, when Britain has made another dip beneath the sea and has come up again, some geologist applies this doctrine, in comparing the strata laid bare by the upheaval of the bottom, say, of St. George's Channel with what may then remain of the Suffolk Crag. Reasoning in the same way, he will at once decide the Suffolk Crag and the St. George's Channel beds to be contemporaneous; although we happen to know that a vast period (even in the geological sense) of time, and physical changes of almost unprecedented extent, separate the two. But if it be a demonstrable fact that strata containing more than 60 or 70 per cent. of species of Mollusca in common, and comparatively close together, may yet be separated by an amount of geological time sufficient to allow of some of the greatest physical changes the world has seen, what becomes of that sort of contemporaneity the sole evidence of which is a similarity of facies, or the identity of half a dozen species, or of a good many genera? And yet there is no better evidence for the contemporaneity assumed by all who adopt the hypotheses of universal faunæ and floræ, of a universally uniform climate, and of a sensible cooling of the globe during geological time. There seems, then, no escape from the admission that neither physical geology, nor palæontology, possesses any method by which the absolute synchronism of two strata can be demonstrated. All that geology can prove is local order of succession. It is mathematically certain that, in any given vertical linear section of an undisturbed series of sedimentary deposits, the bed which lies lowest is the oldest. In any other vertical linear section of the same series, of course, corresponding beds will occur in a similar order; but, however great may be the probability, no man can say with absolute certainty that the beds in the two sections were synchronously deposited. For areas of moderate extent, it is doubtless true that no practical evil is likely to result from assuming the corresponding beds to be synchronous or strictly contemporaneous; and there are multitudes of accessory circumstances which may fully justify the assumption of such synchrony. But the moment the geologist has to deal with large areas, or with completely separated deposits, the mischief of confounding that "homotaxis" or "similarity of arrangement," which _can_ be demonstrated, with "synchrony" or "identity of date," for which there is not a shadow of proof, under the one common term of "contemporaneity" becomes incalculable, and proves the constant source of gratuitous speculations. For anything that geology or palæontology are able to show to the contrary, a Devonian fauna and flora in the British Islands may have been contemporaneous with Silurian life in North America, and with a Carboniferous fauna and flora in Africa. Geographical provinces and zones may have been as distinctly marked in the Palæozoic epoch as at present, and those seemingly sudden appearances of new genera and species, which we ascribe to new creation, may be simple results of migration. It may be so; it may be otherwise. In the present condition of our knowledge and of our methods, one verdict--"not proven, and not proveable"--must be recorded against all the grand hypotheses of the palæontologist respecting the general succession of life on the globe. The order and nature of terrestrial life, as a whole, are open questions. Geology at present provides us with most valuable topographical records, but she has not the means of working them up into a universal history. Is such a universal history, then, to be regarded as unattainable? Are all the grandest and most interesting problems which offer themselves to the geological student essentially insoluble? Is he in the position of a scientific Tantalus--doomed always to thirst for a knowledge which he cannot obtain? The reverse is to be hoped; nay, it may not be impossible to indicate the source whence help will come. In commencing these remarks, mention was made of the great obligations under which the naturalist lies to the geologist and palæontologist. Assuredly the time will come when these obligations will be repaid tenfold, and when the maze of the world's past history, through which the pure geologist and the pure palæontologist find no guidance, will be securely threaded by the clue furnished by the naturalist. All who are competent to express an opinion on the subject are, at present, agreed that the manifold varieties of animal and vegetable form have not either come into existence by chance, nor result from capricious exertions of creative power; but that they have taken place in a definite order, the statement of which order is what men of science term a natural law. Whether such a law is to be regarded as an expression of the mode of operation of natural forces, or whether it is simply a statement of the manner in which a supernatural power has thought fit to act, is a secondary question, so long as the existence of the law and the possibility of its discovery by the human intellect are granted. But he must be a half-hearted philosopher who, believing in that possibility, and having watched the gigantic strides of the biological sciences during the last twenty years, doubts that science will sooner or later make this further step, so as to become possessed of the law of evolution of organic forms--of the unvarying order of that great chain of causes and effects of which all organic forms, ancient and modern, are the links. And then, if ever, we shall be able to begin to discuss, with profit, the questions respecting the commencement of life, and the nature of the successive populations of the globe, which so many seem to think are already answered. The preceding arguments make no particular claim to novelty; indeed they have been floating more or less distinctly before the minds of geologists for the last thirty years; and if, at the present time, it has seemed desirable to give them more definite and systematic expression, it is because palæontology is every day assuming a greater importance, and now requires to rest on a basis the firmness of which is thoroughly well assured. Among its fundamental conceptions, there must be no confusion between what is certain and what is more or less probable.[33] But, pending the construction of a surer foundation than palæontology now possesses, it may be instructive, assuming for the nonce the general correctness of the ordinary hypothesis of geological contemporaneity, to consider whether the deductions which are ordinarily drawn from the whole body of palæontological facts are justifiable. The evidence on which such conclusions are based is of two kinds, negative and positive. The value of negative evidence, in connexion with this inquiry, has been so fully and clearly discussed in an address from the chair of this Society,[34] which none of us have forgotten, that nothing need at present be said about it; the more, as the considerations which have been laid before you have certainly not tended to increase your estimation of such evidence. It will be preferable to turn to the positive facts of palæontology, and to inquire what they tell us. We are all accustomed to speak of the number and the extent of the changes in the living population of the globe during geological time as something enormous; and indeed they are so, if we regard only the negative differences which separate the older rocks from the more modern, and if we look upon specific and generic changes as great changes, which from one point of view they truly are. But leaving the negative differences out of consideration, and looking only at the positive data furnished by the fossil world from a broader point of view--from that of the comparative anatomist who has made the study of the greater modifications of animal form his chief business--a surprise of another kind dawns upon the mind; and under _this_ aspect the smallness of the total change becomes as astonishing as was its greatness under the other. There are two hundred known orders of plants; of these not one is certainly known to exist exclusively in the fossil state. The whole lapse of geological time has as yet yielded not a single new ordinal type of vegetable structure.[35] The positive change in passing from the recent to the ancient animal world is greater, but still singularly small. No fossil animal is so distinct from those now living as to require to be arranged even in a separate class from those which, contain existing forms. It is only when we come to the orders, which may be roughly estimated at about a hundred and thirty, that we meet with fossil animals so distinct from those now living as to require orders for themselves; and these do not amount, on the most liberal estimate, to more than about 10 per cent, of the whole. There is no certainly known extinct order of Protozoa; there is but one among the C�lenterata--that of the rugose corals; there is none among the Mollusca; there are three, the Cystidea, Blastoidea, and Edrioasterida, among the Echinoderms; and two, the Trilobita and Eurypterida, among the Crustacea; making altogether five for the great sub-kingdom of Annulosa. Among Vertebrates there is no ordinally distinct fossil fish: there is only one extinct order of Amphibia--the Labyrinthodonts; but there are at least four distinct orders of Reptilia, viz. the Ichthyosauria, Plesiosauria, Pterosauria, Dinosauria, and perhaps another or two. There is no known extinct order of Birds, and no certainly known extinct order of Mammals, the ordinal distinctness of the "Toxodontia" being doubtful. The objection that broad statements of this kind, after all, rest largely on negative evidence is obvious, but it has less force than may at first be supposed; for, as might be expected from the circumstances of the case, we possess more abundant positive evidence regarding Fishes and marine Mollusks than respecting any other forms of animal life; and yet these offer us, through the whole range of geological time, no species ordinarily distinct from those now living; while the far less numerous class of Echinoderms presents three, and the Crustacea two, such orders, though none of these come down later than the Palæozoic age. Lastly, the Reptilia present the extraordinary and exceptional phænomenon of as many extinct as existing orders, if not more; the four mentioned maintaining their existence from the Lias to the Chalk inclusive. Some years ago one of your Secretaries pointed out another kind of positive palæontological evidence tending towards the same conclusion--afforded by the existence of what he termed "persistent types" of vegetable and of animal life.[36] He stated, on the authority of Dr. Hooker, that there are Carboniferous plants which appear to be generically identical with some now living; that the cone of the Oolitic _Araucaria_ is hardly distinguishable from that of an existing species; that a true _Pinus_ appears in the Purbecks and a _Juglans_ in the Chalk; while, from the Bagshot Sands, a _Banksia_, the wood of which is not distinguishable from that of species now living in Australia, had been obtained. Turning to the animal kingdom, he affirmed the tabulate corals of the Silurian rocks to be wonderfully like those which now exist; while even the families of the Aporosa were all represented in the older Mesozoic rocks. Among the Mollusca similar facts were adduced. Let it be borne in mind that _Avicula_, _Mytilus_, _Chiton_, _Natica_, _Patella_, _Trochus_, _Discina_, _Orbicula_, _Lingula_, _Rhynchonella_, and _Nautilus_, all of which are existing _genera_, are given without a doubt as Silurian in the last edition of "Siluria;" while the highest forms of the highest Cephalopods are represented in the Lias by a genus, _Belemnoteuthis_, which presents the closest relation to the existing _Loligo_. The two highest groups of the Annulosa, the Insecta and the Arachnida, are represented in the Coal, either by existing genera, or by forms differing from existing genera in quite minor peculiarities. Turning to the Vertebrata, the only palæozoic Elasmobranch Fish of which we have any complete knowledge is the Devonian and Carboniferous _Pleuracanthus_, which differs no more from existing Sharks than these do from one another. Again, vast as is the number of undoubtedly Ganoid fossil Fishes, and great as is their range in time, a large mass of evidence has recently been adduced to show that almost all those respecting which we possess sufficient information, are referable to the same sub-ordinal groups as the existing _Lepidosteus_, _Polypterus_, and Sturgeon; and that a singular relation obtains between the older and the younger Fishes; the former, the Devonian Ganoids, being almost all members of the same sub-order as _Polypterus_, while the Mesozoic Ganoids are almost all similarly allied to _Lepidosteus_.[37] Again, what can be more remarkable than the singular constancy of structure preserved throughout a vast period of time by the family of the Pycnodonts and by that of the true Coelacanths: the former persisting, with but insignificant modifications, from the Carboniferous to the Tertiary rocks, inclusive; the latter existing, with still less change, from the Carboniferous rocks to the Chalk, inclusive? Among Reptiles, the highest living group, that of the Crocodilia, is represented, at the early part of the Mesozoic epoch, by species identical in the essential characters of their organization with those now living, and differing from the latter only in such matters as the form of the articular facets of the vertebral centra, in the extent to which the nasal passages are separated from the cavity of the mouth by bone, and in the proportions of the limbs. And even as regards the Mammalia, the scanty remains of Triassic and Oolitic species afford no foundation for the supposition that the organization of the oldest forms differed nearly so much from some of those which now live as these differ from one another. It is needless to multiply these instances; enough has been said to justify the statement that, in view of the immense diversity of known animal and vegetable forms, and the enormous lapse of time indicated by the accumulation of fossiliferous strata, the only circumstance to be wondered at is, not that the changes of life, as exhibited by positive evidence, have been so great, but that they have been so small. Be they great or small, however, it is desirable to attempt to estimate them. Let us, therefore, take each great division of the animal world in succession, and, whenever an order or a family can be shown to have had a prolonged existence, let us endeavour to ascertain how far the later members of the group differ from the earlier ones. If these later members, in all or in many cases, exhibit a certain amount of modification, the fact is so far, evidence in favour of a general law of change; and, in a rough way, the rapidity of that change will be measured by the demonstrable amount of modification. On the other hand, it must be recollected that the absence of any modification, while it may leave the doctrine of the existence of a law of change without positive support, cannot possibly disprove all forms of that doctrine, though it may afford a sufficient refutation of many of them. The PROTOZOA.--The Protozoa are represented throughout the whole range of geological series, from the Lower Silurian formation to the present day. The most ancient forms recently made known by Ehrenberg are exceedingly like those which now exist: no one has ever pretended that the difference between any ancient and any modern Foraminifera is of more than generic value; nor are the oldest Foraminifera either simpler, more embryonic, or less differentiated, than the existing forms. The C�LENTERATA.--The Tabulate Corals have existed from the Silurian epoch to the present day, but I am not aware that the ancient _Heliolites_ possesses a single mark of a more embryonic or less differentiated character, or less high organization, than the existing _Heliopora_. As for the Aporose Corals, in what respect is the Silurian _Paloeocydus_ less highly organized or more embryonic than the modern _Fungia_, or the Liassic Aporosa than the existing members of the same families? The _Mollusca_.--In what sense is the living _Waldheimia_ less embryonic, or more specialized, than the palæozoic _Spirifer_; or the existing _Rhynchonellæ_, _Craniæ_, _Discinæ_, _Lingulæ_, than the Silurian species of the same genera? In what sense can _Loligo_ or _Spirula_ be said to be more specialized, or less embryonic, than _Belemnites_; or the modern species of Lamellibranch and Gasteropod genera, than the Silurian species of the same genera? The ANNULOSA.--The Carboniferous Insecta and Arachnida are neither less specialized, nor more embryonic, than those that now live, nor are the Liassic Cirripedia and Macrura; while several of the Brachyura, which appear in the Chalk, belong to existing genera; and none exhibit either an intermediate, or an embryonic, character. The VERTEBRATA.--Among fishes I have referred to the Coelacanthini (comprising the genera _Coelacanthus_, _Holophagus_, _Undina_, and _Macropoma_) as affording an example of a persistent type; and it is most remarkable to note the smallness of the differences between any of these fishes (affecting at most the proportions of the body and fins, and the character and sculpture of the scales), notwithstanding their enormous range in time. In all the essentials of its very peculiar structure, the _Macropoma_ of the Chalk is identical with the _Coelacanthus_ of the Coal. Look at the genus _Lepidotus_, again, persisting without a modification of importance from the Liassic to the Eocene formations, inclusive. Or among the Teleostei--in what respect is the _Beryx_ of the Chalk more embryonic, or less differentiated, than _Beryx lineatus_ of King George's Sound? Or to turn to the higher Vertebrata--in what sense are the Liassic Chelonia inferior to those which now exist? How are the Cretaceous Ichthyosauria, Plesiosauria, or Pterosauria less embryonic, or more differentiated, species than those of the Lias? Or lastly, in what circumstance is the _Phascolotherium_ more embryonic, or of a more generalized type, than the modern Opossum; or a _Lophiodon_, or a _Palæotherium_, than a modern _Tapirus_ or _Hyrax_? These examples might be almost indefinitely multiplied, but surely they are sufficient to prove that the only safe and unquestionable testimony we can procure--positive evidence--fails to demonstrate any sort of progressive modification towards a less embryonic, or less generalized, type in a great many groups of animals of long-continued geological existence. In these groups there is abundant evidence of variation--none of what is ordinarily understood as progression; and, if the known geological record is to be regarded as even any considerable fragment of the whole, it is inconceivable that any theory of a necessarily progressive development can stand, for the numerous orders and families cited afford no trace of such a process. But it is a most remarkable fact, that, while the groups which have been mentioned, and many besides, exhibit no sign of progressive modification, there are others, coexisting with them, under the same conditions, in which more or less distinct indications of such a process seem to be traceable. Among such indications I may remind you of the predominance of Holostome Gasteropoda in the older rocks as compared with that of Siphonostome Gasteropoda in the later. A case less open to the objection of negative evidence, however, is that afforded by the Tetrabranchiate Cephalopoda, the forms of the shells and of the septal sutures exhibiting a certain increase of complexity in the newer genera. Here, however, one is met at once with the occurrence of _Orthoceras_ and _Baculites_ at the two ends of the series, and of the fact that one of the simplest genera, _Nautilus_, is that which now exists. The Crinoidea, in the abundance of stalked forms in the ancient formations as compared with their present rarity, seem to present us with a fair case of modification from a more embryonic towards a less embryonic condition. But then, on careful consideration of the facts, the objection arises that the stalk, calyx, and arms of the palæozoic Crinoid are exceedingly different from the corresponding organs of a larval _Comatula_; and it might with perfect justice be argued that _Actinocrinus_ and _Eucalyptocrinus_, for example, depart to the full as widely, in one direction, from the stalked embryo of _Comatula_, as _Comatula_ itself does in the other. The Echinidea, again, are frequently quoted as exhibiting a gradual passage from a more generalized to a more specialized type, seeing that the elongated, or oval, Spatangoids appear after the spheroidal Echinoids. But here it might be argued, on the other hand, that the spheroidal Echinoids, in reality, depart further from the general plan and from the embryonic form than the elongated Spatangoids do; and that the peculiar dental apparatus and the pedicellariæ of the former are marks of at least as great differentiation as the petaloid ambulacra and semitæ of the latter. Once more, the prevalence of Macrurous before Brachyurous Podophthalmia is, apparently, a fair piece of evidence in favour of progressive modification in the same order of Crustacea; and yet the case will not stand much sifting, seeing that the Macrurous Podophthalmia depart as far in one direction from the common type of Podophthalmia, or from any embryonic condition of the Brachyura, as the Brachyura do in the other; and that the middle terms between Macrura and Brachyura--the Anomura--are little better represented in the older Mesozoic rocks than the Brachyura are. None of the cases of progressive modification which are cited from among the Invertebrata appear to me to have a foundation less open to criticism than these; and if this be so, no careful reasoner would, I think, be inclined to lay very great stress upon them. Among the Vertebrata, however, there are a few examples which appear to be far less open to objection. It is, in fact, true of several groups of Vertebrata which have lived through a considerable range of time, that the endoskeleton (more particularly the spinal column) of the older genera presents a less ossified, and, so far, less differentiated, condition than that of the younger genera. Thus the Devonian Ganoids, though almost all members of the same sub-order as _Polypterus,_ and presenting numerous important resemblances to the existing genus, which possesses biconcave vertebræ, are, for the most part, wholly devoid of ossified vertebral centra. The Mesozoic Lepidosteidæ, again, have, at most, biconcave vertebræ, while the existing _Lepidosteus_ has Salamandroid, opisthocoelous, vertebræ. So, none of the Palæozoic Sharks have shown themselves to be possessed of ossified vertebræ, while the majority of modern Sharks possess such vertebræ. Again, the more ancient Crocodilia and Lacertilia have vertebræ with the articular facets of their centra flattened or biconcave, while the modern members of the same group have them procoelous. But the most remarkable examples of progressive modification of the vertebral column, in correspondence with geological age, are those afforded by the Pycnodonts among fish, and the Labyrinthodonts among Amphibia. The late able ichthyologist Heckel pointed out the fact, that, while the Pycnodonts never possess true vertebral centra, they differ in the degree of expansion and extension of the ends of the bony arches of the vertebræ upon the sheath of the notochord; the Carboniferous forms exhibiting hardly any such expansion, while the Mesozoic genera present a greater and greater development, until, in the Tertiary forms, the expanded ends become suturally united so as to form a sort of false vertebra. Hermann von Meyer, again, to whose luminous researches we are indebted for our present large knowledge of the organization of the older Labyrinthodonts, has proved that the Carboniferous _Archegosaurus_ had very imperfectly developed vertebral centra, while the Triassic _Mastodonsaurus_ had the same parts completely ossified.[38] The regularity and evenness of the dentition of the _Anoplotherium_, as contrasted with that of existing Artiodactyles, and the assumed nearer approach of the dentition of certain ancient Carnivores to the typical arrangement, have also been cited as exemplifications of a law of progressive development, but I know of no other cases based on positive evidence which are worthy of particular notice. What then does an impartial survey of the positively ascertained truths of palæontology testify in relation to the common doctrines of progressive modification, which suppose that modification to have taken place by a necessary progress from more to less embryonic forms, or from more to less generalized types, within the limits of the period represented by the fossiliferous rocks? It negatives those doctrines; for it either shows us no evidence of any such modification, or demonstrates it to have been very slight; and as to the nature of that modification, it yields no evidence whatsoever that the earlier members of any long-continued group were more generalized in structure than the later ones. To a certain extent, indeed, it may be said that imperfect ossification of the vertebral column is an embryonic character; but, on the other hand, it would be extremely incorrect to suppose that the vertebral columns of the older Vertebrata are in any sense embryonic in their whole structure. Obviously, if the earliest fossiliferous rocks now known are coeval with the commencement of life, and if their contents give us any just conception of the nature and the extent of the earliest fauna and flora, the insignificant amount of modification which can be demonstrated to have taken place in any one group of animals, or plants, is quite incompatible with the hypothesis that all living forms are the results of a necessary process of progressive development, entirely comprised within the time represented by the fossiliferous rocks. Contrariwise, any admissible hypothesis of progressive modification must be compatible with persistence without progression, through indefinite periods. And should such an hypothesis eventually be proved to be true, in the only way in which it can be demonstrated, viz. by observation and experiment upon the existing forms of life, the conclusion will inevitably present itself, that the Palæozoic, Mesozoic, and Cainozoic faunæ and floræ, taken together, bear somewhat the same proportion to the whole series of living beings which have occupied this globe, as the existing fauna and flora do to them. Such are the results of palæontology as they appear, and have for some years appeared, to the mind of an inquirer who regards that study simply as one of the applications of the great biological sciences, and who desires to see it placed upon the same sound basis as other branches of physical inquiry. If the arguments which have been brought forward are valid, probably no one, in view of the present state of opinion, will be inclined to think the time wasted which has been spent upon their elaboration. FOOTNOTES: [33] "Le plus grand service qu'on puisse rendre à la science est d'y faire place nette avant d'y rien construire."--CUVIER. [34] Anniversary Address for 1851, Quart. Journ. Geol. Soc. vol. vii. [35] See Hooker's "Introductory Essay to the Flora of Tasmania," p. xxiii. [36] See the abstract of a Lecture "On the Persistent Types of Animal Life" in the "Notices of the Meetings of the Royal Institution of Great Britain," June 3, 1859, vol. iii. p. 151. [37] "Memoirs of the Geological Survey of the United Kingdom.--Decade x. Preliminary Essay upon the Systematic Arrangement of the Fishes of the Devonian Epoch." [38] As this Address is passing through the press (March 7, 1862), evidence lies before me of the existence of a new Labyrinthodont (_Pholidogaster_), from the Edinburgh coal-field, with well-ossified vertebral centra. XI. GEOLOGICAL REFORM. "A great reform in geological speculation seems now to have become necessary." "It is quite certain that a great mistake has been made,--that British popular geology at the present time is in direct opposition to the principles of Natural Philosophy."[39] In reviewing the course of geological thought during the past year, for the purpose of discovering those matters to which I might most fitly direct your attention in the Address which it now becomes my duty to deliver from the Presidential Chair, the two somewhat alarming sentences which I have just read, and which occur in an able and interesting essay by an eminent natural philosopher, rose into such prominence before my mind that they eclipsed everything else. It surely is a matter of paramount importance for the British geologists (some of them very popular geologists too) here in solemn annual session assembled, to inquire whether the severe judgment thus passed upon them, by so high an authority as Sir William Thomson is one to which they must plead guilty _sans phrase_, or whether they are prepared to say "not guilty," and appeal for a reversal of the sentence to that higher court of educated scientific opinion to which we are all amenable. As your attorney-general for the time being, I thought I could not do better than get up the case with a view of advising you. It is true that the charges brought forward by the other side involve the consideration of matters quite foreign to the pursuits with which I am ordinarily occupied; but, in that respect, I am only in the position which is, nine times out of ten, occupied by counsel, who nevertheless contrive to gain their causes, mainly by force of mother-wit and common sense, aided by some training in other intellectual exercises. Nerved by such precedents, I proceed to put my pleading before you. And the first question with which I propose to deal is, What is it to which Sir W. Thomson refers when he speaks of "geological speculation" and "British popular geology"? I find three, more or less contradictory, systems of geological thought, each of which might fairly enough claim these appellations, standing side by side in Britain. I shall call one of them CATASTROPHISM, another UNIFORMITARIANISM, the third EVOLUTIONISM; and I shall try briefly to sketch the characters of each, that you may say whether the classification is, or is not, exhaustive. By CATASTROPHISM, I mean any form of geological speculation which, in order to account for the phænomena of geology, supposes the operation of forces different in their nature, or immeasurably different in power, from those which we at present see in action in the universe. The Mosaic cosmogony is, in this sense, catastrophic, because it assumes the operation of extra-natural power. The doctrine of violent upheavals, _débâcles_, and cataclysms in general, is catastrophic, so far as it assumes that these were brought about by causes which have now no parallel. There was a time when catastrophism might, pre-eminently, have claimed the title of "British popular geology;" and assuredly it has yet many adherents, and reckons among its supporters some of the most honoured members of this Society. By UNIFORMITARIANISM, I mean especially, the teaching of Hutton and of Lyell. That great, though incomplete work, "The Theory of the Earth," seems to me to be one of the most remarkable contributions to geology which is recorded in the annals of the science. So far as the not-living world is concerned, uniformitarianism lies there, not only in germ, but in blossom and fruit. If one asks how it is that Hutton was led to entertain views so far in advance of those prevalent in his time, in some respects; while, in others, they seem almost curiously limited, the answer appears to me to be plain. Hutton was in advance of the geological speculation of his time, because, in the first place, he had amassed a vast store of knowledge of the facts of geology, gathered by personal observation in travels of considerable extent; and because, in the second place, he was thoroughly trained in the physical and chemical science of his day, and thus possessed, as much as any one in his time could possess it, the knowledge which is requisite for the just interpretation of geological phænomena, and the habit of thought which fits a man for scientific inquiry. It is to this thorough scientific training, that I ascribe Hutton's steady and persistent refusal to look to other causes than those now in operation, for the explanation of geological phænomena. Thus he writes:--"I do not pretend, as he [M. de Luc] does in his theory, to describe the beginning of things. I take things such as I find them at present; and from these I reason with regard to that which must have been."[40] And again:--"A theory of the earth, which has for object truth, can have no retrospect to that which had preceded the present order of the world; for this order alone is what we have to reason upon; and to reason without data is nothing but delusion. A theory, therefore, which is limited to the actual constitution of this earth cannot be allowed to proceed one step beyond the present order of things."[41] And so clear is he, that no causes beside such as are now in operation are needed to account for the character and disposition of the components of the crust of the earth, that he says, broadly and boldly:-- "... There is no part of the earth which has not had the same origin, so far as this consists in that earth being collected at the bottom of the sea, and afterwards produced, as land, along with masses of melted substances, by the operation of mineral causes."[42] But other influences were at work upon Hutton beside those of a mind logical by Nature, and scientific by sound training; and the peculiar turn which his speculations took seems to me to be unintelligible, unless these be taken into account. The arguments of the French astronomers and mathematicians, which, at the end of the last century, were held to demonstrate the existence of a compensating arrangement among the celestial bodies, whereby all perturbations eventually reduced themselves to oscillations on each side of a mean position, and the stability of the solar system was secured, had evidently taken strong hold of Hutton's mind. In those oddly constructed periods which seem to have prejudiced many persons against reading his works, but which are full of that peculiar, if unattractive, eloquence which flows from mastery of the subject, Hutton says:-- "We have now got to the end of our reasoning; we have no data further to conclude immediately from that which actually is. But we have got enough; we have the satisfaction to find, that in Nature there is wisdom, system, and consistency. For having, in the natural history of this earth, seen a succession of worlds, we may from this conclude that there is a system in Nature; in like manner as, from seeing revolutions of the planets, it is concluded, that there is a system by which they are intended to continue those revolutions. But if the succession of worlds is established in the system of Nature, it is in vain to look for anything higher in the origin of the earth. The result, therefore, of this physical inquiry is, that we find no vestige of a beginning,--no prospect of an end."[43] Yet another influence worked strongly upon Hutton. Like most philosophers of his age, he coquetted with those final causes which have been named barren virgins, but which might be more fitly termed the _hetairæ_ of philosophy, so constantly have they led men astray. The final cause of the existence of the world is, for Hutton, the production of life and intelligence. "We have now considered the globe of this earth as a machine, constructed upon chemical as well as mechanical principles, by which its different parts are all adapted, in form, in quality, and in quantity, to a certain end; an end attained with certainty or success; and an end from which we may perceive wisdom, in contemplating the means employed. "But is this world to be considered thus merely as a machine, to last no longer than its parts retain their present position, their proper forms and qualities? Or may it not be also considered as an organized body? such as has a constitution in which the necessary decay of the machine is naturally repaired, in the exertion of those productive powers by which it had been formed. "This is the view in which we are now to examine the globe; to see if there be, in the constitution of this world, a reproductive operation, by which a ruined constitution may be again repaired, and a duration or stability thus procured to the machine, considered as a world sustaining plants and animals."[44] Kirwan, and the other Philistines of the day, accused Hutton of declaring that his theory implied that the world never had a beginning, and never differed in condition from its present state. Nothing could be more grossly unjust, as he expressly guards himself against any such conclusion in the following terms:-- "But in thus tracing back the natural operations which have succeeded each other, and mark to us the course of time past, we come to a period in which we cannot see any farther. This, however, is not the beginning of the operations which proceed in time and according to the wise economy of this world; nor is it the establishing of that which, in the course of time, had no beginning; it is only the limit of our retrospective view of those operations which have come to pass in time, and have been conducted by supreme intelligence."[45] I have spoken of Uniformitarianism as the doctrine of Hutton and of Lyell. If I have quoted the older writer rather than the newer, it is because his works are little known, and his claims on our veneration too frequently forgotten, not because I desire to dim the fame of his eminent successor. Few of the present generation of geologists have read Playfair's "Illustrations," fewer still the original "Theory of the Earth;" the more is the pity; but which of us has not thumbed every page of the "Principles of Geology?" I think that he who writes fairly the history of his own progress in geological thought, will not be able to separate his debt to Hutton from his obligations to Lyell; and the history of the progress of individual geologists is the history of geology. No one can doubt that the influence of uniformitarian views has been enormous, and, in the main, most beneficial and favourable to the progress of sound geology. Nor can it be questioned that Uniformitarianism has even a stronger title than Catastrophism to call itself the geological speculation of Britain, or, if you will, British popular geology. For it is eminently a British doctrine, and has even now made comparatively little progress on the continent of Europe. Nevertheless it seems to me to be open to serious criticism upon one of its aspects. I have shown how unjust was the insinuation that Hutton denied a beginning to the world. But it would not be unjust to say that he persistently, in practice, shut his eyes to the existence of that prior and different state of things which, in theory, he admitted; and, in this aversion to look beyond the veil of stratified rocks, Lyell follows him. Hutton and Lyell alike agree in their indisposition to carry their speculations a step beyond the period recorded in the most ancient strata now open to observation in the crust of the earth. This is, for Hutton, "the point in which we cannot see any farther;" while Lyell tells us,-- "The astronomer may find good reasons for ascribing the earth's form to the original fluidity of the mass, in times long antecedent to the first introduction of living beings into the planet; but the geologist must be content to regard the earliest monuments which it is his task to interpret, as belonging to a period when the crust had already acquired great solidity and thickness, probably as great as it now possesses, and when volcanic rocks, not essentially differing from those now produced, were formed from time to time, the intensity of volcanic heat being neither greater nor less than it is now."[46] And again, "As geologists, we learn that it is not only the present condition of the globe which has been suited to the accommodation of myriads of living creatures, but that many former states also have been adapted to the organization and habits of prior races of beings. The disposition of the seas, continents and islands, and the climates, have varied; the species likewise have been changed; and yet they have all been so modelled, on types analogous to those of existing plants and animals, as to indicate, throughout, a perfect harmony of design and unity of purpose. To assume that the evidence of the beginning, or end, of so vast a scheme lies within the reach of our philosophical inquiries, or even of our speculations, appears to be inconsistent with a just estimate of the relations which subsist between the finite powers of man and the attributes of an infinite and eternal Being."[47] The limitations implied in these passages appear to me to constitute the weakness and the logical defect of uniformitarianism. No one will impute blame to Hutton that, in face of the imperfect condition, in his day, of those physical sciences which furnish the keys to the riddles of geology, he should have thought it practical wisdom to limit his theory to an attempt to account for "the present order of things;" but I am at a loss to comprehend why, for all time, the geologist must be content to regard the oldest fossiliferous rocks as the _ultima Thule_ of his science; or what there is inconsistent with the relations between the finite and the infinite mind, in the assumption, that we may discern somewhat of the beginning, or of the end, of this speck in space we call our earth. The finite mind is certainly competent to trace out the development of the fowl within the egg; and I know not on what ground it should find more difficulty in unravelling the complexities of the development of the earth. In fact, as Kant has well remarked,[48] the cosmical process is really simpler than the biological. This attempt to limit, at a particular point, the progress of inductive and deductive reasoning from the things which are, to those which were--this faithlessness to its own logic, seems to me to have cost Uniformitarianism the place, as the permanent form of geological speculation, which it might otherwise have held. It remains that I should put before you what I understand to be the third phase of geological speculation--namely, EVOLUTIONISM. I shall not make what I have to say on this head clear, unless I diverge, or seem to diverge, for a while, from the direct path of my discourse, so far as to explain what I take to be the scope of geology itself. I conceive geology to be the history of the earth, in precisely the same sense as biology is the history of living beings; and I trust you will not think that I am overpowered by the influence of a dominant pursuit if I say that I trace a close analogy between these two histories. If I study a living being, under what heads does the knowledge I obtain fall? I can learn its structure, or what we call its ANATOMY; and its DEVELOPMENT, or the series of changes which it passes through to acquire its complete structure. Then I find that the living being has certain powers resulting from its own activities, and the interaction of these with the activities of other things--the knowledge of which is PHYSIOLOGY. Beyond this the living being has a position in space and time, which is its DISTRIBUTION. All these form the body of ascertainable facts which constitute the _status quo_ of the living creature. But these facts have their causes; and the ascertainment of these causes is the doctrine of ÆTIOLOGY. If we consider what is knowable about the earth, we shall find that such earth-knowledge--if I may so translate the word geology--falls into the same categories. What is termed stratigraphical geology is neither more nor less than the anatomy of the earth; and the history of the succession of the formations is the history of a succession of such anatomies, or corresponds with development, as distinct from generation. The internal heat of the earth, the elevation and depression of its crust, its belchings forth of vapours, ashes, and lava, are its activities, in as strict a sense, as are warmth and the movements and products of respiration the activities of an animal. The phænomena of the seasons, of the trade winds, of the Gulf-stream, are as much the results of the reaction between these inner activities and outward forces, as are the budding of the leaves in spring and their falling in autumn the effects of the interaction between the organization of a plant and the solar light and heat. And, as the study of the activities of the living being is called its physiology, so are these phænomena the subject-matter of an analogous telluric physiology, to which we sometimes give the name of meteorology, sometimes that of physical geography, sometimes that of geology. Again, the earth has a place in space and in time, and relations to other bodies in both these respects, which constitute its distribution. This subject is usually left to the astronomer; but a knowledge of its broad outlines seems to me to be an essential constituent of the stock of geological ideas. All that can be ascertained concerning the structure, succession of conditions, actions, and position in space of the earth, is the matter of fact of its natural history. But, as in biology, there remains the matter of reasoning from these facts to their causes, which is just as much science as the other, and indeed more; and this constitutes geological ætiology. Having regard to this general scheme of geological knowledge and thought, it is obvious that geological speculation may be, so to speak, anatomical and developmental speculation, so far as it relates to points of stratigraphical arrangement which are out of reach of direct observation; or, it may be physiological speculation, so far as it relates to undetermined problems relative to the activities of the earth; or, it may be distributional speculation, if it deals with modifications of the earth's place in space; or, finally, it will be ætiological speculation, if it attempts to deduce the history of the world, as a whole, from the known properties of the matter of the earth, in the conditions in which the earth has been placed. For the purposes of the present discourse I may take this last to be what is meant by "geological speculation." Now uniformitarianism, as we have seen, tends to ignore geological speculation in this sense altogether. The one point the catastrophists and the uniformitarians agreed upon, when this Society was founded, was to ignore it. And you will find, if you look back into our records, that our revered fathers in geology plumed themselves a good deal upon the practical sense and wisdom of this proceeding. As a temporary measure, I do not presume to challenge its wisdom; but in all organized bodies temporary changes are apt to produce permanent effects; and as time has slipped by, altering all the conditions which may have made such mortification of the scientific flesh desirable, I think the effect of the stream of cold water which has steadily flowed over geological speculation within these walls, has been of doubtful beneficence. The sort of geological speculation to which I am now referring (geological ætiology, in short) was created, as a science, by that famous philosopher Immanuel Kant, when, in 1755, he wrote his "General Natural History and Theory of the Celestial Bodies; or an Attempt to account for the Constitution and the mechanical Origin of the Universe upon Newtonian principles."[49] In this very remarkable, but seemingly little-known treatise,[50] Kant expounds a complete cosmogony, in the shape of a theory of the causes which have led to the development of the universe from diffused atoms of matter endowed with simple attractive and repulsive forces. "Give me matter," says Kant, "and I will build the world;" and he proceeds to deduce from the simple data from which he starts, a doctrine in all essential respects similar to the well-known "Nebular Hypothesis" of Laplace.[51] He accounts for the relation of the masses and the densities of the planets to their distances from the sun, for the eccentricities of their orbits, for their rotations, for their satellites, for the general agreement in the direction of rotation among the celestial bodies, for Saturn's ring, and for the zodiacal light. He finds, in each system of worlds, indications that the attractive force of the central mass will eventually destroy its organization, by concentrating upon itself the matter of the whole system; but, as the result of this concentration, he argues for the development of an amount of heat which will dissipate the mass once more into a molecular chaos such as that in which it began. Kant pictures to himself the universe as once an infinite expansion of formless and diffused matter. At one point of this he supposes a single centre of attraction set up; and, by strict deductions from admitted dynamical principles, shows how this must result in the development of a prodigious central body, surrounded by systems of solar and planetary worlds in all stages of development. In vivid language he depicts the great world-mælstrom, widening the margins of its prodigious eddy in the slow progress of millions of ages, gradually reclaiming more and more of the molecular waste, and converting chaos into cosmos. But what is gained at the margin is lost in the centre; the attractions of the central systems bring their constituents together, which then, by the heat evolved, are converted once more into molecular chaos. Thus the worlds that are, lie between the ruins of the worlds that have been and the chaotic materials of the worlds that shall be; and, in spite of all waste and destruction, Cosmos is extending his borders at the expense of Chaos. Kant's further application of his views to the earth itself is to be found in his "Treatise on Physical Geography"[52] (a term under which the then unknown science of geology was included), a subject which he had studied with very great care and on which he lectured for many years. The fourth section of the first part of this Treatise is called "History of the great Changes which the Earth has formerly undergone and is still undergoing," and is, in fact, a brief and pregnant essay upon the principles of geology. Kant gives an account first "of the gradual changes which are now taking place" under the heads of such as are caused by earthquakes, such as are brought about by rain and rivers, such as are effected by the sea, such as are produced by winds and frost; and, finally, such as result from the operations of man. The second part is devoted to the "Memorials of the Changes which the Earth has undergone in remote antiquity." These are enumerated as:--A. Proofs that the sea formerly covered the whole earth. B. Proofs that the sea has often been changed into dry land and then again into sea. C. A discussion of the various-theories of the earth put forward by Scheuchzer, Moro, Bonnet, Woodward, White, Leibnitz, Linnæus, and Buffon. The third part contains an "Attempt to give a sound explanation of the ancient history of the earth." I suppose that it would be very easy to pick holes in the details of Kant's speculations, whether cosmological, or specially telluric, in their application. But, for all that, he seems to me to have been the first person to frame a complete system of geological speculation by founding the doctrine of evolution. With as much truth as Hutton, Kant could say, "I take things just as I find them at present, and, from these, I reason with regard to that which must have been." Like Hutton, he is never tired of pointing out that "in Nature there is wisdom, system, and consistency." And, as in these great principles, so in believing that the cosmos has a reproductive operation "by which a ruined constitution may be repaired," he forestalls Hutton; while, on the other hand, Kant is true to science. He knows no bounds to geological speculation but those of the intellect. He reasons back to a beginning of the present state of things; he admits the possibility of an end. I have said that the three schools of geological speculation which I have termed Catastrophism, Uniformitarianism, and Evolutionism are commonly supposed to be antagonistic to one another; and I presume it will have become obvious that, in my belief, the last is destined to swallow up the other two. But it is proper to remark that each of the latter has kept alive the tradition of precious truths. CATASTROPHISM has insisted upon the existence of a practically unlimited bank of force, on which the theorist might draw; and it has cherished the idea of the development of the earth from a state in which its form, and the forces which it exerted, were very different from those we now know. That such difference of form and power once existed is a necessary part of the doctrine of evolution. UNIFORMITARIANISM, on the other hand, has with equal justice insisted upon a practically unlimited bank of time, ready to discount any quantity of hypothetical paper. It has kept before our eyes the power of the infinitely little, time being granted, and has compelled us to exhaust known causes, before flying to the unknown. To my mind there appears to be no sort of necessary theoretical antagonism between Catastrophism and Uniformitarianism. On the contrary, it is very conceivable that catastrophes may be part and parcel of uniformity. Let me illustrate my case by analogy. The working of a clock is a model of uniform action; good time-keeping means uniformity of action. But the striking of the clock is essentially a catastrophe; the hammer might be made to blow up a barrel of gunpowder, or turn on a deluge of water; and, by proper arrangement, the clock, instead of marking the hours, might strike at all sorts of irregular periods, never twice alike, in the intervals, force, or number of its blows. Nevertheless, all these irregular, and apparently lawless, catastrophes would be the result of an absolutely uniformitarian action; and we might have two schools of clock-theorists, one studying the hammer and the other the pendulum. Still less is there any necessary antagonism between either of these doctrines and that of Evolution, which embraces all that is sound in both Catastrophism and Uniformitarianism, while it rejects the arbitrary assumptions of the one and the, as arbitrary, limitations of the other. Nor is the value of the doctrine of Evolution to the philosophic thinker diminished by the fact that it applies the same method to the living and the not-living world; and embraces, in one stupendous analogy, the growth of a solar system from molecular chaos, the shaping of the earth from the nebulous cubhood of its youth, through innumerable changes and immeasurable ages, to its present form; and the development of a living being from the shapeless mass of protoplasm we term a germ. I do not know whether Evolutionism can claim that amount of currency which would entitle it to be called British popular geology; but, more or less vaguely, it is assuredly present in the minds of most geologists. Such being the three phases of geological speculation, we are now in a position to inquire which of these it is that Sir William Thomson calls upon us to reform in the passages which I have cited. It is obviously Uniformitarianism which the distinguished physicist takes to be the representative of geological speculation in general. And thus a first issue is raised, inasmuch as many persons (and those not the least thoughtful among the younger geologists) do not accept strict Uniformitarianism as the final form of geological speculation. We should say, if Hutton and Playfair declare the course of the world to have been always the same, point out the fallacy by all means; but, in so doing, do not imagine that you are proving modern geology to be in opposition to natural philosophy. I do not suppose that, at the present day, any geologist would be found to maintain absolute Uniformitarianism, to deny that the rapidity of the rotation of the earth _may_ be diminishing, that the sun _may_ be waxing dim, or that the earth itself _may_ be cooling. Most of us, I suspect, are Gallios, "who care for none of these things," being of opinion that, true or fictitious, they have made no practical difference to the earth, during the period of which, a record is preserved in stratified deposits. The accusation that we have been running counter to the _principles_ of natural philosophy, therefore, is devoid of foundation. The only question which can arise is whether we have, or have not, been tacitly making assumptions which are in opposition to certain conclusions which may be drawn from those principles. And this question subdivides itself into two:--the first, are we really contravening such conclusions? the second, if we are, are those conclusions so firmly based that we may not contravene them? I reply in the negative to both these questions, and I will give you my reasons for so doing. Sir William Thomson believes that he is able to prove, by physical reasonings, "that the existing state of things on the earth, life on the earth--all geological history showing continuity of life--must be limited within some such period of time as one hundred million years" (loc. cit. p. 25). The first inquiry which arises plainly is, has it ever been denied that this period _may_ be enough for the purposes of geology? The discussion of this question is greatly embarrassed by the vagueness with which the assumed limit is, I will not say defined, but indicated,--"some such period of past time as one hundred million years." Now does this mean that it may have been two, or three, or four hundred million years? Because this really makes all the difference.[53] I presume that 100,000 feet may be taken as a full allowance for the total thickness of stratified rocks containing traces of life; 100,000 divided by 100,000,000 = 0.001. Consequently, the deposit of 100,000 feet of stratified rock in 100,000,000 years means that the deposit has taken place at the rate of 1/1000 of a foot, or, say, 1/83 of an inch, per annum. Well, I do not know that any one is prepared to maintain that, even making all needful allowances, the stratified rocks may not have been formed, on the average, at the rate of 1/83 of an inch per annum. I suppose that if such could be shown to be the limit of world-growth, we could put up with the allowance without feeling that our speculations had undergone any revolution. And perhaps, after all, the qualifying phrase "some such period" may not necessitate the assumption of more than 1/166, or 1/249, or 1/332 of an inch of deposit per year, which, of course, would give us still more ease and comfort. But, it may be said, that it is biology, and not geology, which asks for so much time--that the succession of life demands vast intervals; but this appears to me to be reasoning in a circle. Biology takes her time from geology. The only reason we have for believing in the slow rate of the change in living forms is the fact that they persist through a series of deposits which, geology informs us, have taken a long while to make. If the geological clock is wrong, all the naturalist will have to do is to modify his notions of the rapidity of change accordingly. And I venture to point out that, when we are told that the limitation of the period during which living beings have inhabited this planet to one, two, or three hundred million years requires a complete revolution in geological speculation, the _onus probandi_ rests on the maker of the assertion, who brings forward not a shadow of evidence in its support. Thus, if we accept the limitation of time placed before us by Sir W. Thomson, it is not obvious, on the face of the matter, that we shall have to alter, or reform, our ways in any appreciable degree; and we may therefore proceed with much calmness, and indeed much indifference, as to the result, to inquire whether that limitation is justified by the arguments employed in its support. These arguments are three in number:-- I. The first is based upon the undoubted fact that the tides tend to retard the rate of the earth's rotation upon its axis. That this must be so is obvious, if one considers, roughly, that the tides result from the pull which the sun and the moon exert upon the sea, causing it to act as a sort of break upon the rotating solid earth. Kant, who was by no means a mere "abstract philosopher," but a good mathematician and well versed in the physical science of his time, not only proved this in an essay of exquisite clearness and intelligibility, now more than a century old,[54] but deduced from it some of its more important consequences, such as the constant turning of one face of the moon towards the earth. But there is a long step from the demonstration of a tendency to the estimation of the practical value of that tendency, which is all with which we are at present concerned. The facts bearing on this point appear to stand as follow:-- It is a matter of observation that the moon's mean motion is (and has for the last 3,000 years been) undergoing an acceleration, relatively to the rotation of the earth. Of course this may result from one of two causes: the moon may really have been moving more swiftly in its orbit; or the earth may have been rotating more slowly on its axis. Laplace believed he had accounted for this phænomenon by the fact that the eccentricity of the earth's orbit has been diminishing throughout these 3,000 years. This would produce a diminution of the mean attraction of the sun on the moon; or, in other words, an increase in the attraction of the earth on the moon: and, consequently, an increase in the rapidity of the orbital motion of the latter body. Laplace, therefore, laid the responsibility of the acceleration upon the moon; and if his views were correct, the tidal retardation must either be insignificant in amount, or be counteracted by some other agency. Our great astronomer, Adams, however, appears to have found a flaw in Laplace's calculation, and to have shown that only half the observed retardation could be accounted for in the way he had suggested. There remains, therefore, the other half to be accounted for; and here, in the absence of all positive knowledge, three sets of hypotheses have been suggested. (a) M. Delaunay suggests that the earth is at fault, in consequence of the tidal retardation. Messrs. Adams, Thomson, and Tait work out this suggestion, and, "on a certain assumption as to the proportion of retardations due to the sun and the moon," find the earth may lose twenty-two seconds of time in a century from this cause.[55] (b) But M. Dufour suggests that the retardation of the earth (which is hypothetically assumed to exist) may be due in part, or wholly, to the increase of the moment of inertia of the earth by meteors falling upon its surface. This suggestion also meets with the entire approval of Sir W. Thomson, who shows that meteor-dust, accumulating at the rate of one foot in 4,000 years, would account for the remainder of retardation.[56] (c) Thirdly, Sir W. Thomson brings forward an hypothesis of his own with respect to the cause of the hypothetical retardation of the earth's rotation:-- "Let us suppose ice to melt from the polar regions (20° round each pole, we may say) to the extent of something more than a foot thick, enough to give 1.1 foot of water over those areas, or 0.006 of a foot of water if spread over the whole globe, which would, in reality, raise the sea-level by only some such undiscoverable difference as three-fourths of an inch or an inch. This, or the reverse, which we believe might happen any year, and could certainly not be detected without far more accurate observations and calculations for the mean sea-level than any hitherto made, would slacken or quicken the earth's rate as a timekeeper by one-tenth of a second per year."[57] I do not presume to throw the slightest doubt upon the accuracy of any of the calculations made by such distinguished mathematicians as those who have made the suggestions I have cited. On the contrary, it is necessary to my argument to assume that they are all correct. But I desire to point out that this seems to be one of the many cases in which the admitted accuracy of mathematical processes is allowed to throw a wholly inadmissible appearance of authority over the results obtained by them. Mathematics may be compared to a mill of exquisite workmanship, which grinds you stuff of any degree of fineness; but, nevertheless, what you get out depends on what you put in; and as the grandest mill in the world will not extract wheat-flour from peascods, so pages of formulæ will not get a definite result out of loose data. In the present instance it appears to be admitted:-- 1. That it is not absolutely certain, after all, whether the moon's mean motion is undergoing acceleration, or the earth's rotation retardation.[58] And yet this is the key of the whole position. 2. If the rapidity of the earth's rotation is diminishing, it is not certain how much of that retardation is due to tidal friction,--how much to meteors,--how much to possible excess of melting over accumulation of polar ice, during the period covered by observation, which amounts, at the outside, to not more than 2,600 years. 3. The effect of a different distribution of land and water in modifying the retardation caused by tidal friction, and of reducing it, under some circumstances, to a minimum, does not appear to be taken into account. 4. During the Miocene epoch the polar ice was certainly many feet thinner than it has been during, or since, the Glacial epoch. Sir W. Thomson tells us that the accumulation of something more than a foot of ice around the poles (which implies the withdrawal of, say, an inch of water from the general surface of the sea) will cause the earth to rotate quicker by one-tenth of a second per annum. It would appear, therefore, that the earth may have been rotating, throughout the whole period which has elapsed from the commencement of the Glacial epoch down to the present time, one, or more, seconds per annum quicker than it rotated during the Miocene epoch. But, according to Sir W. Thomson's calculation, tidal retardation will only account for a retardation of 22" in a century, or 22/100 (say 1/5) of a second per annum. Thus, assuming that the accumulation of polar ice since the Miocene epoch has only been sufficient to produce ten times the effect of a coat of ice one foot thick, we shall have an accelerating cause which covers all the loss from tidal action, and leaves a balance of 4/5 a second per annum in the way of acceleration. If tidal retardation can be thus checked and overthrown by other temporary conditions, what becomes of the confident assertion, based upon the assumed uniformity of tidal retardation, that ten thousand million years ago the earth must have been rotating more than twice as fast as at present, and, therefore, that we geologists are "in direct opposition to the principles of Natural Philosophy" if we spread geological history over that time? II. The second argument is thus stated by Sir W. Thomson:--"An article, by myself, published in 'Macmillan's Magazine' for March 1862, on the age of the sun's heat, explains results of investigation into various questions as to possibilities regarding the amount of heat that the sun could have, dealing with it as you would with a stone, or a piece of matter, only taking into account the sun's dimensions, which showed it to be possible that the sun may have already illuminated the earth for as many as one hundred million years, but at the same time rendered it almost certain that he had not illuminated the earth for five hundred millions of years. The estimates here are necessarily very vague; but yet, vague as they are, I do not know that it is possible, upon any reasonable estimate founded on known properties of matter, to say that we can believe the sun has really illuminated the earth for five hundred million years."[59] I do not wish to "Hansardize" Sir William Thomson by laying much stress on the fact that, only fifteen years ago, he entertained a totally different view of the origin of the sun's heat, and believed that the energy radiated from year to year was supplied from year to year--a doctrine which would have suited Hutton perfectly. But the fact that so eminent a physical philosopher has, thus recently, held views opposite to those which he now entertains, and that he confesses his own estimates to be "very vague," justly entitles us to disregard those estimates, if any distinct facts on our side go against them. However, I am not aware that such facts exist. As I have already said, for anything I know, one, two, or three hundred millions of years may serve the needs of geologists perfectly well. III. The third line of argument is based upon the temperature of the interior of the earth. Sir W. Thomson refers to certain investigations which prove that the present thermal condition of the interior of the earth implies either a heating of the earth within the last 20,000 years of as much as 100° F., or a greater heating all over the surface at some time further back than 20,000 years, and then proceeds thus:-- "Now, are geologists prepared to admit that, at some time within the last 20,000 years, there has been all over the earth so high a temperature as that? I presume not; no geologist--no _modern_ geologist--would for a moment admit the hypothesis that the present state of underground heat is due to a heating of the surface at so late a period as 20,000 years ago. If that is not admitted, we are driven to a greater heat at some time more than 20,000 years ago. A greater heating all over the surface than 100° Fahrenheit would kill nearly all existing plants and animals, I may safely say. Are modern geologists prepared to say that all life was killed off the earth 50,000, 100,000, or 200,000 years ago? For the uniformity theory, the further back the time of high surface-temperature is put the better; but the further back the time of heating, the hotter it must have been. The best for those who draw most largely on time is that which puts it furthest back; and that is the theory that the heating was enough to melt the whole. But even if it was enough to melt the whole, we must still admit some limit, such as fifty million years, one hundred million years, or two or three hundred million years ago. Beyond that we cannot go."[60] It will be observed that the "limit" is once again of the vaguest, ranging from 50,000,000 years to 300,000,000. And the reply is, once more, that, for anything that can be proved to the contrary, one or two hundred million years might serve the purpose, even of a thorough-going Huttonian uniformitarian, very well. But if, on the other hand, the 100,000,000 or 200,000,000 years appear to be insufficient for geological purposes, we must closely criticise the method by which the limit is reached. The argument is simple enough. _Assuming_ the earth to be nothing but a cooling mass, the quantity of heat lost per year, _supposing_ the rate of cooling to have been uniform, multiplied by any given number of years, will be given the minimum temperature that number of years ago. But is the earth nothing but a cooling mass, "like a hot-water jar such as is used in carriages," or "a globe of sandstone?" and has its cooling been uniform? An affirmative answer to both these questions seems to be necessary to the validity of the calculations on which Sir W. Thomson lays so much stress. Nevertheless it surely may be urged that such affirmative answers are purely hypothetical, and that other suppositions have an equal right to consideration. For example, is it not possible that, at the prodigious temperature which would seem to exist at 100 miles below the surface, all the metallic bases may behave as mercury does at a red heat, when it refuses to combine with oxygen; while, nearer the surface, and therefore at a lower temperature, they may enter into combination (as mercury does with oxygen a few degrees below its boiling-point) and so give rise to a heat totally distinct from that which they possess as cooling bodies? And has it not also been proved by recent researches that the quality of the atmosphere may immensely affect its permeability to heat; and, consequently, profoundly modify the rate of cooling the globe as a whole? I do not think it can be denied that such conditions may exist, and may so greatly affect the supply, and the loss, of terrestrial heat as to destroy the value of any calculations which leave them out of sight. My functions as your advocate are at an end. I speak with more than the sincerity of a mere advocate when I express the belief that the case against us has entirely broken down. The cry for reform which has been raised without, is superfluous, inasmuch as we have long been reforming from within, with all needful speed. And the critical examination of the grounds upon which the very grave charge of opposition to the principles of Natural Philosophy has been brought against us, rather shows that we have exercised a wise discrimination in declining, for the present, to meddle with our foundations. FOOTNOTES: [39] On Geological Time. By Sir W. Thomson, LL.D. Transactions of the Geological Society of Glasgow, vol. iii. [40] The Theory of the Earth, vol. i. p. 173, note. [41] Ibid. p. 281. [42] Ibid. p. 371. [43] The Theory of the Earth, vol. i. p. 200. [44] The Theory of the Earth, vol. i. pp. 16, 17. [45] The Theory of the Earth, vol. i. p. 223. [46] Principles of Geology, vol. ii. p. 211. [47] Principles of Geology, vol. ii. p. 613. [48] "Man darf es sich also nicht befremden lassen, wenn ich mich unterstehe zu sagen, dass eher die Bildung aller Himmelskörper, die Ursache ihrer Bewegungen, kurz der Ursprung der ganzen gegenwärtigen Verfassung des Weltbaues werden können eingesehen werden, ehe die Erzeugung eines einzigen Krautes oder einer Raupe aus mechanischen Gründen, deutlich und vollständig kund werden wird."--KANT'S _Sämmtliche Werke_, Bd. I. p. 220. [49] Grant ("History of Physical Astronomy," p. 574) makes but the briefest reference to Kant. [50] "Allgemeine Naturgeschichte und Theorie des Himmels; oder Versuch von der Verfassung und dem mechanischen Ursprunge des ganzen Weltgebäudes nach Newton'schen Grundsatzen abgehandelt."--KANT'S _Sämmtliche Werke_, Bd. i. p. 207. [51] Système du Monde, tome ii. chap. 6 [52] Kant's "Sämmtliche Werke," Bd. viii. p. 145. [53] Sir William Thomson implies (loc. cit. p. 16), that the precise time is of no consequence: "the principle is the same;" but, as the principle is admitted, the whole discussion turns on its practical results. [54] "Untersuchung der Frage ob die Erde in ihrer Umdrehung um die Achse, wodurch sie die Abwechselung des Tages und der Nacht hervorbringt, einige Veränderung seit den ersten Zeiten ihres Ursprunges erlitten habe, &c."--KANT'S _Sämmtliche Werke_, Bd. i. p. 178. [55] Sir W. Thomson, loc. cit., p. 14. [56] Loc. cit., p. 27 [57] Ibid. [58] It will be understood that I do not wish to deny that the earth's rotation _may be_ undergoing retardation. [59] Loc. cit., p. 20. [60] Loc. cit., p. 24. XII. THE ORIGIN OF SPECIES. Mr. Darwin's long-standing and well-earned scientific eminence probably renders him indifferent to that social notoriety which passes by the name of success; but if the calm spirit of the philosopher have not yet wholly superseded the ambition and the vanity of the carnal man within him, he must be well satisfied with the results of his venture in publishing the "Origin of Species." Overflowing the narrow bounds of purely scientific circles, the "species question" divides with Italy and the Volunteers the attention of general society. Everybody has read Mr. Darwin's book, or, at least, has given an opinion upon its merits or demerits; pietists, whether lay or ecclesiastic, decry it with the mild railing which sounds so charitable; bigots denounce it with ignorant invective; old ladies, of both sexes, consider it a decidedly dangerous book, and even savans, who have no better mud to throw, quote antiquated writers to show that its author is no better than an ape himself; while every philosophical thinker hails it as a veritable Whitworth gun in the armory of liberalism; and all competent naturalists and physiologists, whatever their opinions as to the ultimate fate of the doctrines put forth, acknowledge that the work in which they are embodied is a solid contribution to knowledge and inaugurates a new epoch in natural history. Nor has the discussion of the subject been restrained within the limits of conversation. When the public is eager and interested, reviewers must minister to its wants; and the genuine _littérateur_ is too much in the habit of acquiring his knowledge from the book he judges--as the Abyssinian is said to provide himself with steaks from the ox which carries him--to be withheld from criticism of a profound scientific work by the mere want of the requisite preliminary scientific acquirement; while, on the other hand, the men of science who wish well to the new views, no less than those who dispute their validity, have naturally sought opportunities of expressing their opinions. Hence it is not surprising that almost all the critical journals have noticed Mr. Darwin's work at greater or less length; and so many disquisitions, of every degree of excellence, from the poor product of ignorance, too often stimulated by prejudice, to the fair and thoughtful essay of the candid student of Nature, have appeared, that it seems an almost hopeless task to attempt to say anything new upon the question. But it may be doubted if the knowledge and acumen of prejudged scientific opponents, or the subtlety of orthodox special pleaders, have yet exerted their full force in mystifying the real issues of the great controversy which has been set afoot, and whose end is hardly likely to be seen by this generation; so that, at this eleventh hour, and even failing anything new, it may be useful to state afresh that which is true, and to put the fundamental positions advocated by Mr. Darwin in such a form that they may be grasped by those whose special studies lie in other directions. And the adoption of this course may be the more advisable, because notwithstanding its great deserts, and indeed partly on account of them, the "Origin of Species" is by no means an easy book to read--if by reading is implied the full comprehension of an author's meaning. We do not speak jestingly in saying that it is Mr. Darwin's misfortune to know more about the question he has taken up than any man living. Personally and practically exercised in zoology, in minute anatomy, in geology; a student of geographical distribution, not on maps and in museums only, but by long voyages and laborious collection; having largely advanced each of these branches of science, and having spent many years in gathering and sifting materials for his present work, the store of accurately registered facts upon which the author of the "Origin of Species" is able to draw at will is prodigious. But this very superabundance of matter must have been embarrassing to a writer who, for the present, can only put forward an abstract of his views; and thence it arises, perhaps, that notwithstanding the clearness of the style, those who attempt fairly to digest the book find much of it a sort of intellectual pemmican--a mass of facts crushed and pounded into shape, rather than held together by the ordinary medium of an obvious logical bond: due attention will, without doubt, discover this bond, but it is often hard to find. Again, from sheer want of room, much has to be taken for granted which might readily enough be proved; and hence, while the adept, who can supply the missing links in the evidence from his own knowledge, discovers fresh proof of the singular thoroughness with which all difficulties have been considered and all unjustifiable suppositions avoided, at every reperusal of Mr. Darwin's pregnant paragraphs, the novice in biology is apt to complain of the frequency of what he fancies is gratuitous assumption. Thus while it may be doubted if, for some years, any one is likely to be competent to pronounce judgment on all the issues raised by Mr. Darwin, there is assuredly abundant room for him, who, assuming the humbler, though perhaps as useful, office of an interpreter between the "Origin of Species" and the public, contents himself with endeavouring to point out the nature of the problems which it discusses; to distinguish between the ascertained facts and the theoretical views which it contains; and finally, to show the extent to which the explanation it offers satisfies the requirements of scientific logic. At any rate, it is this office which we propose to undertake in the following pages. It may be safely assumed that our readers have a general conception of the nature of the objects to which the word "species" is applied; but it has, perhaps, occurred to few, even of those who are naturalists _ex professo_, to reflect, that, as commonly employed, the term has a double sense and denotes two very different orders of relations. When we call a group of animals, or of plants, a species, we may imply thereby either, that all these animals or plants have some common peculiarity of form or structure; or, we may mean that they possess some common functional character. That part of biological science which deals with form and structure is called Morphology--that which concerns itself with function, Physiology--so that we may conveniently speak of these two senses, or aspects, of "species"--the one as morphological, the other as physiological. Regarded from the former point of view, a species is nothing more than a kind of animal or plant, which is distinctly definable from all others, by certain constant, and not merely sexual, morphological peculiarities. Thus horses form a species, because the group of animals to which that name is applied is distinguished from all others in the world by the following constantly associated characters. They have 1. A vertebral column; 2. Mammæ; 3. A placental embryo; 4. Four legs; 5. A single well-developed toe in each foot provided with a hoof; 6. A bushy tail; and 7. Callosities on the inner sides of both the fore and the hind legs. The asses, again, form a distinct species, because, with the same characters, as far as the fifth in the above list, all asses have tufted tails, and have callosities only on the inner side of the fore legs. If animals were discovered having the general characters of the horse, but sometimes with callosities only on the fore legs, and more or less tufted tails; or animals having the general characters of the ass, but with more or less bushy tails, and sometimes with callosities on both pairs of legs, besides being intermediate in other respects--the two species would have to be merged into one. They could no longer be regarded as morphologically distinct species, for they would not be distinctly definable one from the other. However bare and simple this definition of species may appear to be, we confidently appeal to all practical naturalists, whether zoologists, botanists, or palæontologists, to say if, in the vast majority of cases, they know, or mean to affirm, anything more of the group of animals or plants they so denominate than what has just been stated. Even the most decided advocates of the received doctrines respecting species admit this. "I apprehend," says Professor Owen,[61] "that few naturalists now-a-days, in describing and proposing a name for what they call 'a new _species_,' use that term to signify what was meant by it twenty or thirty years ago; that is, an originally distinct creation, maintaining its primitive distinction by obstructive generative peculiarities. The proposer of the new species now intends to state no more than he actually knows; as, for example, that the differences on which he founds the specific character are constant in individuals of both sexes, so far as observation has reached; and that they are not due to domestication or to artificially superinduced external circumstances, or to any outward influence within his cognizance; that the species is wild, or is such as it appears by Nature." If we consider, in fact, that by far the largest proportion of recorded existing species are known only by the study of their skins, or bones, or other lifeless exuvia; that we are acquainted with none, or next to none, of their physiological peculiarities, beyond those which can be deduced from their structure, or are open to cursory observation; and that we cannot hope to learn more of any of those extinct forms of life which now constitute no inconsiderable proportion of the known Flora and Fauna of the world: it is obvious that the definitions of these species can be only of a purely structural or morphological character. It is probable that naturalists would have avoided much confusion of ideas if they had more frequently borne these necessary limitations of our knowledge in mind. But while it may safely be admitted that we are acquainted with only the morphological characters of the vast majority of species--the functional, or physiological, peculiarities of a few have been carefully investigated, and the result of that study forms a large and most interesting portion of the physiology of reproduction. The student of Nature wonders the more and is astonished the less, the more conversant he becomes with her operations; but of all the perennial miracles she offers to his inspection, perhaps the most worthy of admiration is the development of a plant or of an animal from its embryo. Examine the recently laid egg of some common animal, such as a salamander or a newt. It is a minute spheroid in which the best microscope will reveal nothing but a structureless sac, enclosing a glairy fluid, holding granules in suspension. But strange possibilities lie dormant in that semi-fluid globule. Let a moderate supply of warmth reach its watery cradle, and the plastic matter undergoes changes so rapid and yet so steady and purposelike in their succession, that one can only compare them to those operated by a skilled modeller upon a formless lump of clay. As with an invisible trowel, the mass is divided and subdivided into smaller and smaller portions, until it is reduced to an aggregation of granules not too large to build withal the finest fabrics of the nascent organism. And, then, it is as if a delicate finger traced out the line to be occupied by the spinal column, and moulded the contour of the body; pinching up the head at one end, the tail at the other, and fashioning flank and limb into due salamandrine proportions, in so artistic a way, that, after watching the process hour by hour, one is almost involuntarily possessed by the notion, that some more subtle aid to vision than an achromatic, would show the hidden artist, with his plan before him, striving with skilful manipulation to perfect his work. As life advances, and the young amphibian ranges the waters, the terror of his insect contemporaries, not only are the nutritious particles supplied by its prey, by the addition of which to its frame growth takes place, laid down, each in its proper spot, and in such due proportion to the rest, as to reproduce the form, the colour and the size, characteristic of the parental stock; but even the wonderful powers of reproducing lost parts possessed by these animals are controlled by the same governing tendency. Cut off the legs, the tail, the jaws, separately or all together, and, as Spallanzani showed long ago, these parts not only grow again, but the redintegrated limb is formed on the same type as those which were lost. The new jaw, or leg, is a newt's, and never by any accident more like that of a frog. What is true of the newt is true of every animal and of every plant; the acorn tends to build itself up again into a woodland giant such as that from whose twig it fell; the spore of the humblest lichen reproduces the green or brown incrustation which gave it birth; and at the other end of the scale of life, the child that resembled neither the paternal nor the maternal side of the house would be regarded as a kind of monster. So that the one end to which, in all living beings, the formative impulse is tending--the one scheme which the Archæus of the old speculators strives to carry out, seems to be to mould the offspring into the likeness of the parent. It is the first great law of reproduction, that the offspring tends to resemble its parent or parents, more closely than anything else. Science will some day show us how this law is a necessary consequence of the more general laws which govern matter; but for the present, more can hardly be said than that it appears to be in harmony with them. We know that the phænomena of vitality are not something apart from other physical phænomena, but one with them; and matter and force are the two names of the one artist who fashions the living as well as the lifeless. Hence living bodies should obey the same great laws as other matter--nor, throughout Nature, is there a law of wider application than this, that a body impelled by two forces takes the direction of their resultant. But living bodies may be regarded as nothing but extremely complex bundles of forces held in a mass of matter, as the complex forces of a magnet are held in the steel by its coercive force; and, since the differences of sex are comparatively slight, or, in other words, the sum of the forces in each has a very similar tendency, their resultant, the offspring, may reasonably be expected to deviate but little from a course parallel to either, or to both. Represent the reason of the law to ourselves by what physical metaphor or analogy we will, however, the great matter is to apprehend its existence and the importance of the consequences deducible from it. For things which are like to the same are like to one another, and if, in a great series of generations, every offspring is like its parent, it follows that all the offspring and all the parents must be like one another; and that, given an original parental stock, with the opportunity of undisturbed multiplication, the law in question necessitates the production, in course of time, of an indefinitely large group, the whole of whose members are at once very similar and are blood relations, having descended from the same parent, or pair of parents. The proof that all the members of any given group of animals, or plants, had thus descended, would be ordinarily considered sufficient to entitle them to the rank of physiological species, for most physiologists consider species to be definable as "the offspring of a single primitive stock." But though it is quite true that all those groups we call species _may_, according to the known laws of reproduction, have descended from a single stock, and though it is very likely they really have done so, yet this conclusion rests on deduction and can hardly hope to establish itself upon a basis of observation. And the primitiveness of the supposed single stock, which, after all, is the essential part of the matter, is not only a hypothesis, but one which has not a shadow of foundation, if by "primitive" be meant "independent of any other living being." A scientific definition, of which an unwarrantable hypothesis forms an essential part, carries its condemnation within itself; but even supposing such a definition were, in form, tenable, the physiologist who should attempt to apply it in Nature would soon find himself involved in great, if not inextricable difficulties. As we have said, it is indubitable that offspring _tend_ to resemble the parental organism, but it is equally true that the similarity attained never amounts to identity, either in form or in structure. There is always a certain amount of deviation, not only from the precise characters of a single parent, but when, as in most animals and many plants, the sexes are lodged in distinct individuals, from an exact mean between the two parents. And indeed, on general principles, this slight deviation seems as intelligible as the general similarity, if we reflect how complex the co-operating "bundles of forces" are, and how improbable it is that, in any case, their true resultant shall coincide with any mean between the more obvious characters of the two parents. Whatever be its cause, however, the co-existence of this tendency to minor variation with the tendency to general similarity, is of vast importance in its bearing on the question of the origin of species. As a general rule, the extent to which an offspring differs from its parent is slight enough; but, occasionally, the amount of difference is much more strongly marked, and then the divergent offspring receives the name of a Variety. Multitudes, of what there is every reason to believe are such varieties, are known, but the origin of very few has been accurately recorded, and of these we will select two as more especially illustrative of the main features of variation. The first of them is that of the "Ancon," or "Otter" sheep, of which a careful account is given by Colonel David Humphreys, F.R.S., in a letter to Sir Joseph Banks, published in the Philosophical Transactions for 1813. It appears that one Seth Wright, the proprietor of a farm on the banks of the Charles River, in Massachusetts, possessed a flock of fifteen ewes and a ram of the ordinary kind. In the year 1791, one of the ewes presented her owner with a male lamb, differing, for no assignable reason, from its parents by a proportionally long body and short bandy legs, whence it was unable to emulate its relatives in those sportive leaps over the neighbours' fences, in which they were in the habit of indulging, much to the good farmer's vexation. The second case is that detailed by a no less unexceptionable authority than Réaumur in his "Art de faire éclore les Poulets." A Maltese couple, named Kelleia, whose hands and feet were constructed upon the ordinary human model, had born to them a son, Gratio, who possessed six perfectly moveable fingers on each hand and six toes, not quite so well formed, on each foot. No cause could be assigned for the appearance of this unusual variety of the human species. Two circumstances are well worthy of remark in both these cases. In each, the variety appears to have arisen in full force, and, as it were, _per saltum_; a wide and definite difference appearing, at once, between the Ancon ram and the ordinary sheep; between the six-fingered and six-toed Gratio Kelleia and ordinary men. In neither case is it possible to point out any obvious reason for the appearance of the variety. Doubtless there were determining causes for these as for all other phænomena; but they do not appear, and we can be tolerably certain that what are ordinarily understood as changes in physical conditions, as in climate, in food, or the like, did not take place and had nothing to do with the matter. It was no case of what is commonly called adaptation to circumstances; but, to use a conveniently erroneous phrase, the variations arose spontaneously. The fruitless search after final causes leads their pursuers a long way; but even those hardy teleologists, who are ready to break through all the laws of physics in chase of their favourite will-o'-the-wisp, may be puzzled to discover what purpose could be attained by the stunted legs of Seth Wright's ram or the hexadactyle members of Gratio Kelleia. Varieties then arise we know not why; and it is more than probable that the majority of varieties have arisen in this "spontaneous" manner, though we are, of course, far from denying that they may be traced, in some cases, to distinct external influences; which are assuredly competent to alter the character of the tegumentary covering, to change colour, to increase or diminish the size of muscles, to modify constitution, and, among plants, to give rise to the metamorphosis of stamens into petals, and so forth. But however they may have arisen, what especially interests us at present is, to remark that, once in existence, varieties obey the fundamental law of reproduction that like tends to produce like, and their offspring exemplify it by tending to exhibit the same deviation from the parental stock as themselves. Indeed, there seems to be, in many instances, a pre-potent influence about a newly-arisen variety which gives it what one may call an unfair advantage over the normal descendants from the same stock. This is strikingly exemplified by the case of Gratio Kelleia, who married a woman with the ordinary pentadactyle extremities, and had by her four children, Salvator, George, André, and Marie. Of these children Salvator, the eldest boy, had six fingers and six toes, like his father; the second and third, also boys, had five fingers and five toes, like their mother, though the hands and feet of George were slightly deformed; the last, a girl, had five fingers and five toes, but the thumbs were slightly deformed. The variety thus reproduced itself purely in the eldest, while the normal type reproduced itself purely in the third, and almost purely in the second and last: so that it would seem, at first, as if the normal type were more powerful than the variety. But all these children grew up and intermarried with normal wives and husband, and then, note what took place: Salvator had four children, three of whom exhibited the hexadactyle members of their grandfather and father, while the youngest had the pentadactyle limbs of the mother and grandmother; so that here, notwithstanding a double pentadactyle dilution of the blood, the hexadactyle variety had the best of it. The same pre-potency of the variety was still more markedly exemplified in the progeny of two of the other children, Marie and George. Marie (whose thumbs only were deformed) gave birth to a boy with six toes, and three other normally formed children; but George, who was not quite so pure a pentadactyle, begot, first, two girls, each of whom had six fingers and toes; then a girl with six fingers on each hand and six toes on the right foot, but only five toes on the left; and lastly, a boy with only five fingers and toes. In these instances, therefore, the variety, as it were, leaped over one generation to reproduce itself in full force in the next. Finally, the purely pentadactyle André was the father of many children, not one of whom departed from the normal parental type. If a variation which approaches the nature of a monstrosity can strive thus forcibly to reproduce itself, it is not wonderful that less aberrant modifications should tend to be preserved even more strongly; and the history of the Ancon sheep is, in this respect, particularly instructive. With the "'cuteness" characteristic of their nation, the neighbours of the Massachusetts farmer imagined it would be an excellent thing if all his sheep were imbued with the stay-at-home tendencies enforced by Nature upon the newly-arrived ram; and they advised Wright to kill the old patriarch of his fold, and install the Ancon ram in his place. The result justified their sagacious anticipations, and coincided very nearly with what occurred to the progeny of Gratio Kelleia. The young lambs were almost always either pure Ancons, or pure ordinary sheep.[62] But when sufficient Ancon sheep were obtained to interbreed with one another, it was found that the offspring was always pure Ancon. Colonel Humphreys, in fact, states that he was acquainted with only "one questionable case of a contrary nature." Here, then, is a remarkable and well-established instance, not only of a very distinct race being established _per saltum_, but of that race breeding "true" at once, and showing no mixed forms, even when crossed with another breed. By taking care to select Ancons of both sexes, for breeding from, it thus became easy to establish an extremely well-marked race; so peculiar that, even when herded with other sheep, it was noted that the Ancons kept together. And there is every reason to believe that the existence of this breed might have been indefinitely protracted; but the introduction of the Merino sheep, which were not only very superior to the Ancons in wool and meat, but quite as quiet and orderly, led to the complete neglect of the new breed, so that, in 1813, Colonel Humphreys found it difficult to obtain the specimen, whose skeleton was presented to Sir Joseph Banks. We believe that, for many years, no remnant of it has existed in the United States. Gratio Kelleia was not the progenitor of a race of six-fingered men, as Seth Wright's ram became a nation of Ancon sheep, though the tendency of the variety to perpetuate itself appears to have been fully as strong, in the one case as in the other. And the reason of the difference is not far to seek. Seth Wright took care not to weaken the Ancon blood by matching his Ancon ewes with any but males of the same variety, while Gratio Kelleia's sons were too far removed from the patriarchal times to intermarry with their sisters; and his grandchildren seem not to have been attracted by their six-fingered cousins. In other words, in the one example a race was produced, because, for several generations, care was taken to _select_ both parents of the breeding stock, from animals exhibiting a tendency to vary in the same direction; while, in the other, no race was evolved, because no such selection was exercised. A race is a propagated variety; and as, by the laws of reproduction, offspring tend to assume the parental form, they will be more likely to propagate a variation exhibited by both parents than that possessed by only one. There is no organ of the body of an animal which may not, and does not, occasionally, vary more or less from the normal type; and there is no variation which may not be transmitted, and which, if selectively transmitted, may not become the foundation of a race. This great truth, sometimes forgotten by philosophers, has long been familiar to practical agriculturists and breeders: and upon it rest all the methods of improving the breeds of domestic animals, which, for the last century, have been followed with so much success in England. Colour, form, size, texture of hair or wool, proportions of various parts, strength or weakness of constitution, tendency to fatten or to remain lean, to give much or little milk, speed, strength, temper, intelligence, special instincts; there is not one of these characters whose transmission is not an every-day occurrence within the experience of cattle-breeders, stock-farmers, horse-dealers, and dog and poultry fanciers. Nay, it is only the other day that an eminent physiologist, Dr. Brown-Séquard, communicated to the Royal Society his discovery that epilepsy, artificially produced in guinea-pigs, by a means which he has discovered, is transmitted to their offspring. But a race, once produced, is no more a fixed and immutable entity than the stock whence it sprang; variations arise among its members, and as these variations are transmitted like any others, new races may be developed out of the pre-existing ones _ad infinitum_, or, at least, within any limit at present determined. Given sufficient time and sufficiently careful selection, and the multitude of races which may arise from a common stock is as astonishing as are the extreme structural differences which they may present. A remarkable example of this is to be found in the rock-pigeon, which Mr. Darwin has, in our opinion, satisfactorily demonstrated to be the progenitor of all our domestic pigeons, of which there are certainly more than a hundred well-marked races. The most noteworthy of these races are, the four great stocks known to the "fancy" as tumblers, pouters, carriers, and fantails; birds which not only differ most singularly in size, colour, and habits, but in the form of the beak and of the skull: in the proportions of the beak to the skull; in the number of tail-feathers; in the absolute and relative size of the feet; in the presence or absence of the uropygial gland; in the number of vertebræ in the back; in short, in precisely those characters in which the genera and species of birds differ from one another. And it is most remarkable and instructive to observe, that none of these races can be shown to have been originated by the action of changes in what are commonly called external circumstances, upon the wild rock-pigeon. On the contrary, from time immemorial, pigeon fanciers have had essentially similar methods of treating their pets, which have been housed, fed, protected and cared for in much the same way in all pigeonries. In fact, there is no case better adapted than that of the pigeons, to refute the doctrine which one sees put forth on high authority, that "no other characters than those founded on the development of bone for the attachment of muscles" are capable of variation. In precise contradiction of this hasty assertion, Mr. Darwin's researches prove that the skeleton of the wings in domestic pigeons has hardly varied at all from that of the wild type; while, on the other hand, it is in exactly those respects, such as the relative length of the beak and skull, the number of the vertebræ, and the number of the tail-feathers, in which muscular exertion can have no important influence, that the utmost amount of variation has taken place. We have said that the following out of the properties exhibited by physiological species would lead us into difficulties, and at this point they begin to be obvious; for, if, as a result of spontaneous variation and of selective breeding, the progeny of a common stock may become separated into groups distinguished from one another by constant, not sexual, morphological characters, it is clear that the physiological definition of species is likely to clash with the morphological definition. No one would hesitate to describe the pouter and the tumbler as distinct species, if they were found fossil, or if their skins and skeletons were imported, as those of exotic wild birds commonly are--and, without doubt, if considered alone, they are good and distinct morphological species. On the other hand, they are not physiological species, for they are descended from a common stock, the rock-pigeon. Under these circumstances, as it is admitted on all sides that races occur in Nature, how are we to know whether any apparently distinct animals are really of different physiological species, or not, seeing that the amount of morphological difference is no safe guide? Is there any test of a physiological species? The usual answer of physiologists is in the affirmative. It is said that such a test is to be found in the phænomena of hybridization--in the results of crossing races, as compared with the results of crossing species. So far as the evidence goes at present, individuals, of what are certainly known to be mere races produced by selection, however distinct they may appear to be, not only breed freely together, but the offspring of such crossed races are only perfectly fertile with one another. Thus, the spaniel and the greyhound, the dray-horse and the Arab, the pouter and the tumbler, breed together with perfect freedom, and their mongrels, if matched with other mongrels of the same kind, are equally fertile. On the other hand, there can be no doubt that the individuals of many natural species are either absolutely infertile, if crossed with individuals of other species, or, if they give rise to hybrid offspring, the hybrids so produced are infertile when paired together. The horse and the ass, for instance, if so crossed, give rise to the mule, and there is no certain evidence of offspring ever having been produced by a male and female mule. The unions of the rock-pigeon and the ring-pigeon appear to be equally barren of result. Here, then, says the physiologist, we have a means of distinguishing any two true species from any two varieties. If a male and a female, selected from each group, produce offspring, and that offspring is fertile with others produced in the same way, the groups are races and not species. If, on the other hand, no result ensues, or if the offspring are infertile with others produced in the same way, they are true physiological species. The test would be an admirable one, if, in the first place, it were always practicable to apply it, and if, in the second, it always yielded results susceptible of a definite interpretation. Unfortunately, in the great majority of cases, this touchstone for species is wholly inapplicable. The constitution of many wild animals is so altered by confinement that they will not breed even with their own females, so that the negative results obtained from crosses are of no value; and the antipathy of wild animals of different species for one another, or even of wild and tame members of the same species, is ordinarily so great, that it is hopeless to look for such unions in Nature. The hermaphrodism of most plants, the difficulty in the way of ensuring the absence of their own, or the proper working of other pollen, are obstacles of no less magnitude in applying the test to them. And in both, animals and plants is superadded the further difficulty, that experiments must be continued over a long time for the purpose of ascertaining the fertility of the mongrel or hybrid progeny, as well as of the first crosses from which they spring. Not only do these great practical difficulties lie in the way of applying the hybridization test, but even when this oracle can be questioned, its replies are sometimes as doubtful as those of Delphi. For example, cases are cited by Mr. Darwin, of plants which are more fertile with the pollen of another species than with their own; and there are others, such as certain _fuci_, whose male element will fertilize the ovule of a plant of distinct species, while the males of the latter species are ineffective with the females of the first. So that, in the last-named instance, a physiologist, who should cross the two species in one way, would decide that they were true species; while another, who should cross them in the reverse way, would, with equal justice, according to the rule, pronounce them to be mere races. Several plants, which there is great reason to believe are mere varieties, are almost sterile when crossed; while both animals and plants, which have always been regarded by naturalists as of distinct species, turn out, when the test is applied, to be perfectly fertile. Again, the sterility or fertility of crosses seems to bear no relation to the structural resemblances or differences of the members of any two groups. Mr. Darwin has discussed this question with singular ability and circumspection, and his conclusions are summed up as follow, at page 276 of his work:-- "First crosses between forms sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile. The sterility is of all degrees, and is often so slight that the two most careful experimentalists who have ever lived have come to diametrically opposite conclusions in ranking forms by this test. The sterility is innately variable in individuals of the same species, and is eminently susceptible of favourable and unfavourable conditions. The degree of sterility does not strictly follow systematic affinity, but is governed by several curious and complex laws. It is generally different, and sometimes widely different, in reciprocal crosses between the same two species. It is not always equal in degree in a first cross, and in the hybrid produced from this cross. "In the same manner as in grafting trees, the capacity of one species or variety to take on another is incidental on generally unknown differences in their vegetative systems; so in crossing, the greater or less facility of one species to unite with another is incidental on unknown differences in their reproductive systems. There is no more reason to think that species have been specially endowed with various degrees of sterility to prevent them crossing and breeding in Nature, than to think that trees have been specially endowed with various and somewhat analogous degrees of difficulty in being grafted together, in order to prevent them becoming inarched in our forests. "The sterility of first crosses between pure species, which have their reproductive systems perfect, seems to depend on several circumstances; in some cases largely on the early death of the embryo. The sterility of hybrids which have their reproductive systems imperfect, and which have had this system and their whole organization disturbed by being compounded of two distinct species, seems closely allied to that sterility which so frequently affects pure species when their natural conditions of life have been disturbed. This view is supported by a parallelism of another kind; namely, that the crossing of forms, only slightly different, is favourable to the vigour and fertility of the offspring; and that slight changes in the conditions of life are apparently favourable to the vigour and fertility of all organic beings. It is not surprising that the degree of difficulty in uniting two species, and the degree of sterility of their hybrid offspring, should generally correspond, though due to distinct causes; for both depend on the amount of difference of some kind between the species which are crossed. Nor is it surprising that the facility of effecting a first cross, the fertility of hybrids produced from it, and the capacity of being grafted together--though this latter capacity evidently depends on widely different circumstances--should all run to a certain extent parallel with the systematic affinity of the forms which are subjected to experiment; for systematic affinity attempts to express all kinds of resemblance between all species. "First crosses between forms known to be varieties, or sufficiently alike to be considered as varieties, and their mongrel offspring, are very generally, but not quite universally, fertile. Nor is this nearly general and perfect fertility surprising, when we remember how liable we are to argue in a circle with respect to varieties in a state of Nature; and when we remember that the greater number of varieties have been produced under domestication by the selection of mere external differences, and not of differences in the reproductive system. In all other respects, excluding fertility, there is a close general resemblance between hybrids and mongrels."--Pp. 276-8. We fully agree with the general tenor of this weighty passage; but forcible as are these arguments, and little as the value of fertility or infertility as a test of species may be, it must not be forgotten that the really important fact, so far as the inquiry into the origin of species goes, is, that there are such things in Nature as groups of animals and of plants, whose members are incapable of fertile union with those of other groups; and that there are such things as hybrids, which are absolutely sterile when crossed with other hybrids. For if such phænomena as these were exhibited by only two of those assemblages of living objects, to which the name of species (whether it be used in its physiological or in its morphological sense) is given, it would have to be accounted for by any theory of the origin of species, and every theory which could not account for it would be, so far, imperfect. Up to this point we have been dealing with matters of fact, and the statements which we have laid before the reader would, to the best of our knowledge, be admitted to contain a fair exposition of what is at present known respecting the essential properties of species, by all who have studied the question. And whatever may be his theoretical views, no naturalist will probably be disposed to demur to the following summary of that exposition:-- Living beings, whether animals or plants, are divisible into multitudes of distinctly definable kinds, which are morphological species. They are also divisible into groups of individuals, which breed freely together, tending to reproduce their like, and are physiological species. Normally resembling their parents, the offspring of members of these species are still liable to vary, and the variation may be perpetuated by selection, as a race, which race, in many cases, presents all the characteristics of a morphological species. But it is not as yet proved that a race ever exhibits, when crossed with another race of the same species, those phænomena of hybridization which are exhibited by many species when crossed with other species. On the other hand, not only is it not proved that all species give rise to hybrids infertile _inter se_, but there is much reason to believe that, in crossing, species exhibit every gradation from perfect sterility to perfect fertility. Such are the most essential characteristics of species. Even were man not one of them--a member of the same system and subject to the same laws--the question of their origin, their causal connexion, that is, with the other phænomena of the universe, must have attracted his attention, as soon as his intelligence had raised itself above the level of his daily wants. Indeed history relates that such was the case, and has embalmed for us the speculations upon the origin of living beings, which were among the earliest products of the dawning intellectual activity of man. In those early days positive knowledge was not to be had, but the craving after it needed, at all hazards, to be satisfied, and according to the country, or the turn of thought of the speculator, the suggestion that all living things arose from the mud of the Nile, from a primeval egg, or from some more anthropomorphic agency, afforded a sufficient resting-place for his curiosity. The myths of Paganism are as dead as Osiris or Zeus, and the man who should revive them, in opposition to the knowledge of our time, would be justly laughed to scorn; but the coeval imaginations current among the rude inhabitants of Palestine, recorded by writers whose very name and age are admitted by every scholar to be unknown, have unfortunately not yet shared their fate, but, even at this day, are regarded by nine-tenths of the civilized world as the authoritative standard of fact and the criterion of the justice of scientific conclusions, in all that relates to the origin of things, and, among them, of species. In this nineteenth century, as at the dawn of modern physical science, the cosmogony of the semi-barbarous Hebrew is the incubus of the philosopher and the opprobrium of the orthodox. Who shall number the patient and earnest seekers after truth, from the days of Galileo until now, whose lives have been embittered and their good name blasted by the mistaken zeal of Bibliolaters? Who shall count the host of weaker men whose sense of truth has been destroyed in the effort to harmonize impossibilities--whose life has been wasted in the attempt to force the generous new wine of Science into the old bottles of Judaism, compelled by the outcry of the same strong party? It is true that if philosophers have suffered, their cause has been amply avenged. Extinguished theologians lie about the cradle of every science as the strangled snakes beside that of Hercules; and history records that whenever science and orthodoxy have been fairly opposed, the latter has been forced to retire from the lists, bleeding and crushed, if not annihilated; scotched, if not slain. But orthodoxy is the Bourbon of the world of thought. It learns not, neither can it forget; and though, at present, bewildered and afraid to move, it is as willing as ever to insist that the first chapter of Genesis contains the beginning and the end of sound science; and to visit, with such petty thunderbolts as its half-paralysed hands can hurl, those who refuse to degrade Nature to the level of primitive Judaism. Philosophers, on the other hand, have no such aggressive tendencies. With eyes fixed on the noble goal to which "per aspera et ardua" they tend, they may, now and then, be stirred to momentary wrath by the unnecessary obstacles with which the ignorant, or the malicious, encumber, if they cannot bar, the difficult path; but why should their souls be deeply vexed? The majesty of Fact is on their side, and the elemental forces of Nature are working for them. Not a star comes to the meridian at its calculated time but testifies to the justice of their methods--their beliefs are "one with the falling rain and with the growing corn." By doubt they are established, and open inquiry is their bosom friend. Such men have no fear of traditions however venerable, and no respect for them when they become mischievous and obstructive; but they have better than mere antiquarian business in hand, and if dogmas, which ought to be fossil but are not, are not forced upon their notice, they are too happy to treat them as non-existent. The hypotheses respecting the origin of species which profess to stand upon a scientific basis, and, as such, alone demand serious attention, are of two kinds. The one, the "special creation" hypothesis, presumes every species to have originated from one or more stocks, these not being the result of the modification of any other form of living matter--or arising by natural agencies--but being produced, as such, by a supernatural creative act. The other, the so-called "transmutation" hypothesis, considers that all existing species are the result of the modification of pre-existing species, and those of their predecessors, by agencies similar to those which at the present day produce varieties and races, and therefore in an altogether natural way; and it is a probable, though not a necessary consequence of this hypothesis, that all living beings have arisen from a single stock. With respect to the origin of this primitive stock, or stocks, the doctrine of the origin of species is obviously not necessarily concerned. The transmutation hypothesis, for example, is perfectly consistent either with the conception of a special creation of the primitive germ, or with the supposition of its having arisen, as a modification of inorganic matter, by natural causes. The doctrine of special creation owes its existence very largely to the supposed necessity of making science accord with the Hebrew cosmogony; but it is curious to observe that, as the doctrine is at present maintained by men of science, it is as hopelessly inconsistent with the Hebrew view as any other hypothesis. If there be any result which has come more clearly out of geological investigation than another, it is, that the vast series of extinct animals and plants is not divisible, as it was once supposed to be, into distinct groups, separated by sharply marked boundaries. There are no great gulfs between epochs and formations--no successive periods marked by the appearance of plants, of water animals, and of land animals, _en masse_. Every year adds to the list of links between what the older geologists supposed to be widely separated epochs: witness the crags linking the drift with the older tertiaries; the Maestricht beds linking the tertiaries with the chalk; the St. Cassian beds exhibiting an abundant fauna of mixed mesozoic and palæozoic types, in rocks of an epoch once supposed to be eminently poor in life; witness, lastly, the incessant disputes as to whether a given stratum shall be reckoned devonian or carboniferous, silurian or devonian, cambrian or silurian. This truth is further illustrated in a most interesting manner by the impartial and highly competent testimony of M. Pictet, from whose calculations of what percentage of the genera of animals, existing in any formation, lived during the preceding formation, it results that in no case is the proportion less than _one-third_, or 33 per cent. It is the triassic formation, or the commencement of the mesozoic epoch, which has received this smallest inheritance from preceding ages. The other formations not uncommonly exhibit 60, 80, or even 94 per cent. of genera in common with those whose remains are imbedded in their predecessor. Not only is this true, but the subdivisions of each formation exhibit new species characteristic of, and found only in, them; and, in many cases, as in the lias for example, the separate beds of these subdivisions are distinguished by well-marked and peculiar forms of life. A section, a hundred feet thick, will exhibit, at different heights, a dozen species of ammonite, none of which passes beyond its particular zone of limestone, or clay, into the zone below it or into that above it; so that those who adopt the doctrine of special creation must be prepared to admit that at intervals of time, corresponding with the thickness of these beds, the Creator thought fit to interfere with the natural course of events for the purpose of making a new ammonite. It is not easy to transplant oneself into the frame of mind of those who can accept such a conclusion as this, on any evidence short of absolute demonstration; and it is difficult to see what is to be gained by so doing, since, as we have said, it is obvious that such a view of the origin of living beings is utterly opposed to the Hebrew cosmogony. Deserving no aid from the powerful arm of bibliolatry, then, does the received form of the hypothesis of special creation derive any support from science or sound logic? Assuredly not much. The arguments brought forward in its favour all take one form: If species were not supernaturally created, we cannot understand the facts _x_, or _y_, or _z_; we cannot understand the structure of animals or plants, unless we suppose they were contrived for special ends; we cannot understand the structure of the eye, except by supposing it to have been made to see with; we cannot understand instincts, unless we suppose animals to have been miraculously endowed with them. As a question of dialectics, it must be admitted that this sort of reasoning is not very formidable to those who are not to be frightened by consequences. It is an _argumentum ad ignorantiam_--take this explanation or be ignorant. But suppose we prefer to admit our ignorance rather than adopt a hypothesis at variance with all the teachings of Nature? Or, suppose for a moment we admit the explanation, and then seriously ask ourselves how much the wiser are we; what does the explanation explain? Is it any more than a grandiloquent way of announcing the fact, that we really know nothing about the matter? A phenomenon is explained when it is shown to be a case of some general law of Nature; but the supernatural interposition of the Creator can, by the nature of the case, exemplify no law, and if species have really arisen in this way, it is absurd to attempt to discuss their origin. Or, lastly, let us ask ourselves whether any amount of evidence which the nature of our faculties permits us to attain, can justify us in asserting that any phænomenon is out of the reach of natural causation. To this end it is obviously necessary that we should know all the consequences to which all possible combinations, continued through unlimited time, can give rise. If we knew these, and found none competent to originate species, we should have good ground for denying their origin by natural causation. Till we know them, any hypothesis is better than one which involves us in such miserable presumption. But the hypothesis of special creation is not only a mere specious mask for our ignorance; its existence in Biology marks the youth and imperfection of the science. For what is the history of every science but the history of the elimination of the notion of creative, or other interferences, with the natural order of the phænomena which are the subject-matter of that science? When Astronomy was young "the morning stars sang together for joy," and the planets were guided in their courses by celestial hands. Now, the harmony of the stars has resolved itself into gravitation according to the inverse squares of the distances, and the orbits of the planets are deducible from the laws of the forces which allow a schoolboy's stone to break a window. The lightning was the angel of the Lord; but it has pleased Providence, in these modern times, that science should make it the humble messenger of man, and we know that every flash that shimmers about the horizon on a summer's evening is determined by ascertainable conditions, and that its direction and brightness might, if our knowledge of these were great enough, have been calculated. The solvency of great mercantile companies rests on the validity of the laws which have been ascertained to govern the seeming irregularity of that human life which the moralist bewails as the most uncertain of things; plague, pestilence, and famine are admitted, by all but fools, to be the natural result of causes for the most part fully within human control, and not the unavoidable tortures inflicted by wrathful Omnipotence upon his helpless handiwork. Harmonious order governing eternally continuous progress--the web and woof of matter and force interweaving by slow degrees, without a broken thread, that veil which lies between us and the Infinite--that universe which alone we know or can know; such is the picture which science draws of the world, and in proportion as any part of that picture is in unison with the rest, so may we feel sure that it is rightly painted. Shall Biology alone remain out of harmony with her sister sciences? Such arguments against the hypothesis of the direct creation of species as these are plainly enough deducible from general considerations; but there are, in addition, phænomena exhibited by species themselves, and yet not so much a part of their very essence as to have required earlier mention, which are in the highest degree perplexing, if we adopt the popularly accepted hypothesis. Such are the facts of distribution in space and in time; the singular phænomena brought to light by the study of development; the structural relations of species upon which our systems of classification are founded; the great doctrines of philosophical anatomy, such as that of homology, or of the community of structural plan exhibited by large groups of species differing very widely in their habits and functions. The species of animals which inhabit the sea on opposite sides of the isthmus of Panama are wholly distinct;[63] the animals and plants which inhabit islands are commonly distinct from those of the neighbouring mainlands, and yet have a similarity of aspect. The mammals of the latest tertiary epoch in the Old and New Worlds belong to the same genera, or family groups, as those which now inhabit the same great geographical area. The crocodilian reptiles which existed in the earliest secondary epoch were similar in general structure to those now living, but exhibit slight differences in their vertebræ, nasal passages, and one or two other points. The guinea-pig has teeth which are shed before it is born, and hence can never subserve the masticatory purpose for which they seem contrived, and, in like manner, the female dugong has tusks which never cut the gum. All the members of the same great group run through similar conditions in their development, and all their parts, in the adult state, are arranged according to the same plan. Man is more like a gorilla than a gorilla is like a lemur. Such are a few, taken at random, among the multitudes of similar facts which modern research has established; but when the student seeks for an explanation of them from the supporters of the received hypothesis of the origin of species, the reply he receives is, in substance, of Oriental simplicity and brevity--"Mashallah! it so pleases God!" There are different species on opposite sides of the isthmus of Panama, because they were created different on the two sides. The pliocene mammals are like the existing ones, because such was the plan of creation; and we find rudimental organs and similarity of plan, because it has pleased the Creator to set before himself a "divine exemplar or archetype," and to copy it in his works; and somewhat ill, those who hold this view imply, in some of them. That such verbal hocus-pocus should be received as science will one day be regarded as evidence of the low state of intelligence in the nineteenth century, just as we amuse ourselves with the phraseology about Nature's abhorrence of a vacuum, wherewith Torricelli's compatriots were satisfied to explain the rise of water in a pump. And be it recollected that this sort of satisfaction works not only negative but positive ill, by discouraging inquiry, and so depriving man of the usufruct of one of the most fertile fields of his great patrimony, Nature. The objections to the doctrine of the origin of species by special creation which have been detailed, must have occurred, with more or less force, to the mind of every one who has seriously and independently considered the subject. It is therefore no wonder that, from time to time, this hypothesis should have been met by counter hypotheses, all as well, and some better, founded than itself; and it is curious to remark that the inventors of the opposing views seem to have been led into them as much by their knowledge of geology, as by their acquaintance with biology. In fact, when the mind has once admitted the conception of the gradual production of the present physical state of our globe, by natural causes operating through long ages of time, it will be little disposed to allow that living beings have made their appearance in another way, and the speculations of De Maillet and his successors are the natural complement of Scilla's demonstration of the true nature of fossils. A contemporary of Newton and of Leibnitz, sharing therefore in the intellectual activity of the remarkable age which witnessed the birth of modern physical science, Benoît de Maillet spent a long life as a consular agent of the French Government in various Mediterranean ports. For sixteen years, in fact, he held the office of Consul-General in Egypt, and the wonderful phænomena offered by the valley of the Nile appear to have strongly impressed his mind, to have directed his attention to all facts of a similar order which came within his observation, and to have led him to speculate on the origin of the present condition of our globe and of its inhabitants. But, with all his ardour for science, De Maillet seems to have hesitated to publish views which, notwithstanding the ingenious attempts to reconcile them with the Hebrew hypothesis contained in the preface to "Telliamed," were hardly likely to be received with favour by his contemporaries. But a short time had elapsed since more than one of the great anatomists and physicists of the Italian school had paid dearly for their endeavours to dissipate some of the prevalent errors; and their illustrious pupil, Harvey, the founder of modern physiology, had not fared so well, in a country less oppressed by the benumbing influences of theology, as to tempt any man to follow his example. Probably not uninfluenced by these considerations, his Catholic majesty's Consul-General for Egypt kept his theories to himself throughout a long life, for "Telliamed," the only scientific work which is known to have proceeded from his pen, was not printed till 1735, when its author had reached the ripe age of seventy-nine; and though De Maillet lived three years longer, his book was not given to the world before 1748. Even then it was anonymous to those who were not in the secret of the anagramatic character of its title; and the preface and dedication are so worded as, in case of necessity, to give the printer a fair chance of falling back on the excuse that the work was intended for a mere _jeu d'esprit_. The speculations of the supposititious Indian sage, though quite as sound as those of many a "Mosaic Geology," which sells exceedingly well, have no great value if we consider them by the light of modern science. The waters are supposed to have originally covered the whole globe; to have deposited the rocky masses which compose its mountains by processes comparable to those which are now forming mud, sand, and shingle; and then to have gradually lowered their level, leaving the spoils of their animal and vegetable inhabitants embedded in the strata. As the dry land appeared, certain of the aquatic animals are supposed to have taken to it, and to have become gradually adapted to terrestrial and aërial modes of existence. But if we regard the general tenor and style of the reasoning in relation to the state of knowledge of the day, two circumstances appear very well worthy of remark. The first, that De Maillet had a notion of the modifiability of living forms (though without any precise information on the subject), and how such modifiability might account for the origin of species; the second, that he very clearly apprehended the great modern geological doctrine, so strongly insisted upon by Hutton, and so ably and comprehensively expounded by Lyell, that we must look to existing causes for the explanation of past geological events. Indeed, the following passage of the preface, in which De Maillet is supposed to speak of the Indian philosopher Telliamed, his _alter ego_, might have been written by the most philosophical uniformitarian of the present day:-- "Ce qu'il y a d'étonnant, est que pour arriver à ces connoissances il semble avoir perverti l'ordre naturel, pui-qu'au lieu de s'attacher d'abord à rechercher l'origine de notre globe il a commencé par travailler à s'instruire de la nature. Mais à l'entendre, ce renversement de l'ordre a été pour lui l'effet d'un génie favorable qui l'a conduit pas à pas et comme par la main aux découvertes les plus sublimes. C'est en décomposant la substance de ce globe par une anatomie exacte de toutes ses parties qu'il a premièrement appris de quelles matières il etait composé et quels arrangemens ces mêmes matières observaient entre elles. Ces lumières jointes à l'esprit de comparaison toujours nécessaire à quiconque entreprend de percer les voiles dont la nature aime à se cacher, ont servi de guide à notre philosophe pour parvenir à des connoissances plus intéressantes. Par la matière et l'arrangement de ces compositions il prétend avoir reconnu quelle est la véritable origine de ce globe que nous habitons, comment et par qui il a été formé."--Pp. xix. xx. But De Maillet was before his age, and as could hardly fail to happen to one who speculated on a zoological and botanical question before Linnæus, and on a physiological problem before Haller, he fell into great errors here and there; and hence, perhaps, the general neglect of his work. Robinet's speculations are rather behind, than in advance of, those of De Maillet; and though Linnæus may have played with the hypothesis of transmutation, it obtained no serious support until Lamarck adopted it, and advocated it with great ability in his "Philosophie Zoologique." Impelled towards the hypothesis of the transmutation of species, partly by his general cosmological and geological views; partly by the conception of a graduated, though irregularly branching, scale of being, which had arisen out of his profound study of plants and of the lower forms of animal life, Lamarck, whose general line of thought often closely resembles that of De Maillet, made a great advance upon the crude and merely speculative manner in which that writer deals with the question of the origin of living beings, by endeavouring to find physical causes competent to effect that change of one species into another, which De Maillet had only supposed to occur. And Lamarck conceived that he had found in Nature such causes, amply sufficient for the purpose in view. It is a physiological fact, he says, that organs are increased in size by action, atrophied by inaction; it is another physiological fact that modifications produced are transmissible to offspring. Change the actions of an animal, therefore, and you will change its structure, by increasing the development of the parts newly brought into use and by the diminution of those less used; but by altering the circumstances which surround it you will alter its actions, and hence, in the long run, change of circumstance must produce change of organization. All the species of animals, therefore, are, in Lamarck's view, the result of the indirect action of changes of circumstance upon those primitive germs which he considered to have originally arisen, by spontaneous generation, within the waters of the globe. It is curious, however, that Lamarck should insist so strongly[64] as he has done, that circumstances never in any degree directly modify the form or the organization of animals, but only operate by changing their wants and consequently their actions; for he thereby brings upon himself the obvious question, how, then, do plants, which cannot be said to have wants or actions, become modified? To this he replies, that they are modified by the changes in their nutritive processes, which are effected by changing circumstances; and it does not seem to have occurred to him that such changes might be as well supposed to take place among animals. When we have said that Lamarck felt that mere speculation was not the way to arrive at the origin of species, but that it was necessary, in order to the establishment of any sound theory on the subject, to discover by observation or otherwise, some _vera causa_, competent to give rise to them; that he affirmed the true order of classification to coincide with the order of their development one from another; that he insisted on the necessity of allowing sufficient time, very strongly; and that all the varieties of instinct and reason were traced back by him to the same cause as that which has given rise to species, we have enumerated his chief contributions to the advance of the question. On the other hand, from his ignorance of any power in Nature competent to modify the structure of animals, except the development of parts, or atrophy of them, in consequence of a change of needs, Lamarck was led to attach infinitely greater weight than it deserves to this agency, and the absurdities into which he was led have met with deserved condemnation. Of the struggle for existence, on which, as, we shall see, Mr. Darwin lays such great stress, he had no conception; indeed, he doubts whether there really are such things as extinct species, unless they be such large animals as may have met their death at the hands of man; and so little does he dream of there being any other destructive causes at work, that, in discussing the possible existence of fossil shells, he asks, "Pourquoi d'ailleurs seroient-ils perdues dès que l'homme n'a pu opérer leur destruction?" (Phil. Zool., vol. i. p. 77.) Of the influence of selection Lamarck has as little notion, and he makes no use of the wonderful phænomena which are exhibited by domesticated animals, and illustrate its powers. The vast influence of Cuvier was employed against the Lamarckian views, and, as the untenability of some of his conclusions was easily shown, his doctrines sank under the opprobium of scientific, as well as of theological, heterodoxy. Nor have the efforts made of late years to revive them tended to re-establish their credit in the minds of sound thinkers acquainted with the facts of the case; indeed it may be doubted whether Lamarck has not suffered more from his friends than from his foes. Two years ago, in fact, though we venture to question if even the strongest supporters of the special creation hypothesis had not, now and then, an uneasy consciousness that all was not right, their position seemed more impregnable than ever, if not by its own inherent strength, at any rate by the obvious failure of all the attempts which had been made to carry it. On the other hand, however much the few, who thought deeply on the question of species, might be repelled by the generally received dogmas, they saw no way of escaping from them, save by the adoption of suppositions, so little justified by experiment or by observation, as to be at least equally distasteful. The choice lay between two absurdities and a middle condition of uneasy scepticism; which last, however unpleasant and unsatisfactory, was obviously the only justifiable state of mind under the circumstances. Such being the general ferment in the minds of naturalists, it is no wonder that they mustered strong in the rooms of the Linnæan Society, on the 1st of July of the year 1858, to hear two papers by authors living on opposite sides of the globe, working out their results independently, and yet professing to have discovered one and the same solution of all the problems connected with species. The one of these authors was an able naturalist, Mr. Wallace, who had been employed for some years in studying the productions of the islands of the Indian Archipelago, and who had forwarded a memoir embodying his views to Mr. Darwin, for communication to the Linnæan Society. On perusing the essay, Mr. Darwin was not a little surprised to find that it embodied some of the leading ideas of a great work which he had been preparing for twenty years, and parts of which, containing a development of the very same views, had been perused by his private friends fifteen or sixteen years before. Perplexed in what manner to do full justice both to his friend and to himself, Mr. Darwin placed the matter in the hands of Dr. Hooker and Sir Charles Lyell, by whose advice he communicated a brief abstract of his own views to the Linnæan Society, at the same time that Mr. Wallace's paper was read. Of that abstract, the work on the "Origin of Species" is an enlargement; but a complete statement of Mr. Darwin's doctrine is looked for in the large and well-illustrated work which he is said to be preparing for publication. The Darwinian hypothesis has the merit of being eminently simple and comprehensible in principle, and its essential positions may be stated in a very few words: all species have been produced by the development of varieties from common stocks by the conversion of these first into permanent races and then into new species, by the process of _natural selection_, which process is essentially identical with that artificial selection by which man has originated the races of domestic animals--the _struggle for existence_ taking the place of man, and exerting, in the case of natural selection, that selective action which he performs in artificial selection. The evidence brought forward by Mr. Darwin in support of his hypothesis is of three kinds. First, he endeavours to prove that species may be originated by selection; secondly, he attempts to show that natural causes are competent to exert selection; and thirdly, he tries to prove that the most remarkable and apparently anomalous phænomena exhibited by the distribution, development, and mutual relations of species, can be shown to be deducible from the general doctrine of their origin, which he propounds, combined with the known facts of geological change; and that, even if all these phænomena are not at present explicable by it, none are necessarily inconsistent with it. There cannot be a doubt that the method of inquiry which Mr. Darwin has adopted is not only rigorously in accordance with the canons of scientific logic, but that it is the only adequate method. Critics exclusively trained in classics or in mathematics, who have never determined a scientific fact in their lives by induction from experiment or observation, prate learnedly about Mr. Darwin's method, which is not inductive enough, not Baconian enough, forsooth, for them. But even if practical acquaintance with the process of scientific investigation is denied them, they may learn, by the perusal of Mr. Mill's admirable chapter "On the Deductive Method," that there are multitudes of scientific inquiries, in which the method of pure induction helps the investigator but a very little way. "The mode of investigation," says Mr. Mill, "which, from the proved inapplicability of direct methods of observation and experiment, remains to us as the main source of the knowledge we possess, or can acquire, respecting the conditions and laws of recurrence of the more complex phænomena, is called, in its most general expression, the deductive method, and consists of three operations: the first, one of direct induction; the second, of ratiocination; and the third, of verification." Now, the conditions which have determined the existence of species are not only exceedingly complex, but, so far as the great majority of them are concerned, are necessarily beyond our cognizance. But what Mr. Darwin has attempted to do is in exact accordance with the rule laid down by Mr. Mill; he has endeavoured to determine certain great facts inductively, by observation and experiment; he has then reasoned from the data thus furnished; and lastly, he has tested the validity of his ratiocination by comparing his deductions with the observed facts of Nature. Inductively, Mr. Darwin endeavours to prove that species arise in a given way. Deductively, he desires to show that, if they arise in that way, the facts of distribution, development, classification, &c., may be accounted for, _i.e._ may be deduced from their mode of origin, combined with admitted changes in physical geography and climate, during an indefinite period. And this explanation, or coincidence of observed with deduced facts, is, so far as it extends, a verification of the Darwinian view. There is no fault to be found with Mr. Darwin's method, then; but it is another question whether he has fulfilled all the conditions imposed by that method. Is it satisfactorily proved, in fact, that species may be originated by selection? that there is such a thing as natural selection? that none of the phænomena exhibited by species are inconsistent with the origin of species in this way? If these questions can be answered in the affirmative, Mr. Darwin's view steps out of the ranks of hypotheses into those of proved theories; but, so long as the evidence at present adduced falls short of enforcing that affirmation, so long, to our minds, must the new doctrine be content to remain among the former--an extremely valuable, and in the highest degree probable, doctrine, indeed the only extant hypothesis which is worth anything in a scientific point of view; but still a hypothesis, and not yet the theory of species. After much consideration, and with assuredly no bias against Mr. Darwin's views, it is our clear conviction that, as the evidence stands, it is not absolutely proven that a group of animals, having all the characters exhibited by species in Nature, has ever been originated by selection, whether artificial or natural. Groups having the morphological character of species, distinct and permanent races in fact, have been so produced over and over again; but there is no positive evidence, at present, that any group of animals has, by variation and selective breeding, given rise to another group which was even in the least degree infertile with the first. Mr. Darwin is perfectly aware of this weak point, and brings forward a multitude of ingenious and important arguments to diminish the force of the objection. We admit the value of these arguments to their fullest extent; nay, we will go so far as to express our belief that experiments, conducted by a skilful physiologist, would very probably obtain the desired production of mutually more or less infertile breeds from a common stock, in a comparatively few years; but still, as the case stands at present, this "little rift within the lute" is not to be disguised nor overlooked. In the remainder of Mr. Darwin's argument our own private ingenuity has not hitherto enabled us to pick holes of any great importance; and judging by what we hear and read, other adventurers in the same field do not seem to have been much more fortunate. It has been urged, for instance, that in his chapters on the struggle for existence and on natural selection, Mr. Darwin does not so much prove that natural selection does occur, as that it must occur; but, in fact, no other sort of demonstration is attainable. A race does not attract our attention in Nature until it has, in all probability, existed for a considerable time, and then it is too late to inquire into the conditions of its origin. Again, it is said that there is no real analogy between the selection which takes place under domestication, by human influence, and any operation which can be effected by Nature, for man interferes intelligently. Reduced to its elements, this argument implies that an effect produced with trouble by an intelligent agent must, _à fortiori_, be more troublesome, if not impossible, to an unintelligent agent. Even putting aside the question whether Nature, acting as she does according to definite and invariable laws, can be rightly called an unintelligent agent, such a position as this is wholly untenable. Mix salt and sand, and it shall puzzle the wisest of men, with his mere natural appliances, to separate all the grains of sand from all the grains of salt; but a shower of rain will effect the same object in ten minutes. And so, while man may find it tax all his intelligence to separate any variety which arises, and to breed selectively from it, the destructive agencies incessantly at work in Nature, if they find one variety to be more soluble in circumstances than the other, will inevitably, in the long run, eliminate it. A frequent and a just objection to the Lamarckian hypothesis of the transmutation of species is based upon the absence of transitional forms between many species. But against the Darwinian hypothesis this argument has no force. Indeed, one of the most valuable and suggestive parts of Mr. Darwin's work is that in which he proves, that the frequent absence of transitions is a necessary consequence of his doctrine, and that the stock whence two or more species have sprung, need in no respect be intermediate between these species. If any two species have arisen from a common stock in the same way as the carrier and the pouter, say, have arisen from the rock-pigeon, then the common stock of these two species need be no more intermediate between the two than the rock-pigeon is between the carrier and pouter. Clearly appreciate the force of this analogy, and all the arguments against the origin of species by selection, based on the absence of transitional forms, fall to the ground. And Mr. Darwin's position might, we think, have been even stronger than it is if he had not embarrassed himself with the aphorism, "_Natura non facit saltum_," which turns up so often in his pages. We believe, as we have said above, that Nature does make jumps now and then, and a recognition of the fact is of no small importance in disposing of many minor objections to the doctrine of transmutation. But we must pause. The discussion of Mr. Darwin's arguments in detail would lead us far beyond the limits within which we proposed, at starting, to confine this article. Our object has been attained if we have given an intelligible, however brief, account of the established facts connected with species, and of the relation of the explanation of those facts offered by Mr. Darwin to the theoretical views held by his predecessors and his contemporaries, and, above all, to the requirements of scientific logic. We have ventured to point out that it does not, as yet, satisfy all those requirements; but we do not hesitate to assert that it is as superior to any preceding or contemporary hypothesis, in the extent of observational and experimental basis on which it rests, in its rigorously scientific method, and in its power of explaining biological phænomena, as was the hypothesis of Copernicus to the speculations of Ptolemy. But the planetary orbits turned out to be not quite circular after all, and, grand as was the service Copernicus rendered to science, Kepler and Newton had to come after him. What if the orbit of Darwinism should be a little too circular? What if species should offer residual phænomena, here and there, not explicable by natural selection? Twenty years hence naturalists may be in a position to say whether this is, or is not, the case; but in either event they will owe the author of "The Origin of Species" an immense debt of gratitude. We should leave a very wrong impression on the reader's mind if we permitted him to suppose that the value of that work depends wholly on the ultimate justification of the theoretical views which it contains. On the contrary, if they were disproved to-morrow, the book would still be the best of its kind--the most compendious statement of well-sifted facts bearing on the doctrine of species that has ever appeared. The chapters on Variation, on the Struggle for Existence, on Instinct, on Hybridism, on the Imperfection of the Geological Record, on Geographical Distribution, have not only no equals, but, so far as our knowledge goes, no competitors, within the range of biological literature. And viewed as a whole, we do not believe that, since the publication of Von Baer's Researches on Development, thirty years ago, any work has appeared calculated to exert so large an influence, not only on the future of Biology, but in extending the domination of Science over regions of thought into which she has, as yet, hardly penetrated. FOOTNOTES: [61] On the Osteology of the Chimpanzees and Orangs: Transactions of the Zoological Society, 1858. [62] Colonel Humphreys' statements are exceedingly explicit on this point:--"When an Ancon ewe is impregnated by a common ram, the increase resembles wholly either the ewe or the ram. The increase of the common ewe impregnated by an Ancon ram follows entirely the one or the other, without blending any of the distinguishing and essential peculiarities of both. Frequent instances have happened where common ewes have had twins by Ancon rams, when one exhibited the complete marks and features of the ewe, the other of the ram. The contrast has been rendered singularly striking, when one short-legged and one long-legged lamb, produced at a birth, have been seen sucking the dam at the same time."--_Philosophical Transactions_, 1813, Pt. I., pp. 89, 90. [63] Recent investigations tend to show that this statement is not strictly accurate.--1870. [64] See Phil. Zoologique, vol. i. p. 222, et seq. XIII. CRITICISMS ON "THE ORIGIN OF SPECIES." 1. UEBER DIE DARWIN'SCHE SCHÖPFUNGSTHEORIE; EIN VORTAG, VON A. KÖLLIKER. Leipzig, 1864. 2. EXAMINATION DU LIVRE DE M. DARWIN SUR L'ORIGINE DES ESPÈCES. PAR P. FLOURENS. Paris, 1864. In the course of the present year [1864] several foreign commentaries upon Mr. Darwin's great work have made their appearance. Those who have perused that remarkable chapter of the "Antiquity of Man," in which Sir Charles Lyell draws a parallel between the development of species and that of languages, will be glad to hear that one of the most eminent philologers of Germany, Professor Schleicher, has, independently, published a most instructive and philosophical pamphlet (an excellent notice of which is to be found in the _Reader_, for February 27th of this year) supporting similar views with all the weight of his special knowledge and established authority as a linguist. Professor Haeckel, to whom Schleicher addresses himself, previously took occasion, in his splendid monograph on the _Radiolaria_,[65] to express his high appreciation of, and general concordance with, Mr. Darwin's views. But the most elaborate criticisms of the "Origin of Species" which have appeared are two works of very widely different merit, the one by Professor Kölliker, the well-known anatomist and histologist of Würzburg; the other by M. Flourens, Perpetual Secretary of the French Academy of Sciences. Professor Kölliker's critical essay "Upon the Darwinian Theory" is, like all that proceeds from the pen of that thoughtful and accomplished writer, worthy of the most careful consideration. It comprises a brief but clear sketch of Darwin's views, followed by an enumeration of the leading difficulties in the way of their acceptance; difficulties which would appear to be insurmountable to Professor Kölliker, inasmuch as he proposes to replace Mr. Darwin's Theory by one which he terms the "Theory of Heterogeneous Generation." We shall proceed to consider first the destructive, and secondly, the constructive portion of the essay. We regret to find ourselves compelled to dissent very widely from many of Professor Kölliker's remarks; and from none more thoroughly than from those in which he seeks to define what we may term the philosophical position of Darwinism. "Darwin," says Professor Kölliker, "is, in the fullest sense of the Word, a Teleologist. He says quite distinctly (First Edition, pp. 199, 200) that every particular in the structure of an animal has been created for its benefit, and he regards the whole series of animal forms only from this point of view." And again: "7. The teleological general conception adopted by Darwin is a mistaken one. "Varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent. "The assumption that an organism exists only on account of some definite end in view, and represents something more than the incorporation of a general idea, or law, implies a one-sided conception of the universe. Assuredly, every organ has, and every organism fulfils, its end, but its purpose is not the condition of its existence. Every organism is also sufficiently perfect for the purpose it serves, and in that, at least, it is useless to seek for a cause of its improvement." It is singular how differently one and the same book will impress different minds. That which struck the present writer most forcibly on his first perusal of the "Origin of Species" was the conviction that Teleology, as commonly understood, had received its deathblow at Mr. Darwin's hands. For the teleological argument runs thus: an organ or organism (A) is precisely fitted to perform a function or purpose (B); therefore it was specially constructed to perform that function. In Paley's famous illustration, the adaptation of all the parts of the watch to the function, or purpose, of showing the time, is held to be evidence that the watch was specially contrived to that end; on the ground, that the only cause we know of, competent to produce such an effect as a watch which shall keep time, is a contriving intelligence adapting the means directly to that end. Suppose, however, that any one had been able to show that the watch had not been made directly by any person, but that it was the result of the modification of another watch which kept time but poorly; and that this again had proceeded from a structure which could hardly be called a watch at all--seeing that it had no figures on the dial and the hands were rudimentary; and that going back and back in time we came at last to a revolving barrel as the earliest traceable rudiment of the whole fabric. And imagine that it had been possible to show that all these changes had resulted, first, from a tendency of the structure to vary indefinitely; and secondly, from something in the surrounding world which helped all variations in the direction of an accurate time-keeper, and checked all those in other directions; then it is obvious that the force of Paley's argument would be gone. For it would be demonstrated that an apparatus thoroughly well adapted to a particular purpose might be the result of a method of trial and error worked by unintelligent agents, as well as of the direct application of the means appropriate to that end, by an intelligent agent. Now it appears to us that what we have here, for illustration's sake, supposed to be done with the watch, is exactly what the establishment of Darwin's Theory will do for the organic world. For the notion that every organism has been created as it is and launched straight at a purpose, Mr. Darwin substitutes the conception of something which may fairly be termed a method of trial and error. Organisms vary incessantly; of these variations the few meet with surrounding conditions which suit them and thrive; the many are unsuited and become extinguished. According to Teleology, each organism is like a rifle bullet fired straight at a mark; according to Darwin, organisms are like grapeshot of which one hits something and the rest fall wide. For the teleologist an organism exists because it was made for the conditions in which it is found; for the Darwinian an organism exists because, out of many of its kind, it is the only one which has been able to persist in the conditions in which it is found. Teleology implies that the organs of every organism are perfect and cannot be improved; the Darwinian theory simply affirms that they work well enough to enable the organism to hold its own against such competitors as it has met with, but admits the possibility of indefinite improvement. But an example may bring into clearer light the profound opposition between the ordinary teleological, and the Darwinian, conception. Cats catch mice, small birds and the like, very well. Teleology tells us that they do so because they were expressly constructed for so doing--that they are perfect mousing apparatuses, so perfect and so delicately adjusted that no one of their organs could be altered, without the change involving the alteration of all the rest. Darwinism affirms, on the contrary, that there was no express construction concerned in the matter; but that among the multitudinous variations of the Feline stock, many of which died out from want of power to resist opposing influences, some, the cats, were better fitted to catch mice than others, whence they throve and persisted, in proportion to the advantage over their fellows thus offered to them. Far from imagining that cats exist _in order_ to catch mice well, Darwinism supposes that cats exist _because_ they catch mice well--mousing being not the end, but the condition, of their existence. And if the cat-type has long persisted as we know it, the interpretation of the fact upon Darwinian principles would be, not that the cats have remained invariable, but that such varieties as have incessantly occurred have been, on the whole, less fitted to get on in the world than the existing stock. If we apprehend the spirit of the "Origin of Species" rightly, then, nothing can be more entirely and absolutely opposed to Teleology, as it is commonly understood, than the Darwinian Theory. So far from being a "Teleologist in the fullest sense of the word," we should deny that he is a Teleologist in the ordinary sense at all; and we should say that, apart from his merits as a naturalist, he has rendered a most remarkable service to philosophical thought by enabling the student of Nature to recognise, to their fullest extent, those adaptations to purpose which are so striking in the organic world, and which Teleology has done good service in keeping before our minds, without being false to the fundamental principles of a scientific conception of the universe. The apparently diverging teachings of the Teleologist and of the Morphologist are reconciled by the Darwinian hypothesis. But leaving our own impressions of the "Origin of Species," and turning to those passages specially cited by Professor Kölliker, we cannot admit that they bear the interpretation he puts upon them. Darwin, if we read him rightly, does _not_ affirm that every detail in the structure of an animal has been created for its benefit. His words are (p. 199):-- "The foregoing remarks lead me to say a few words on the protest lately made by some naturalists against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that very many structures have been created for beauty in the eyes of man, or for mere variety. This doctrine, if true, would be absolutely fatal to my theory--yet I fully admit that many structures are of no direct use to their possessor." And after sundry illustrations and qualifications, he concludes (p. 200):-- "Hence every detail of structure in every living creature (making some little allowance for the direct action of physical conditions) may be viewed either as having been of special use to some ancestral form, or as being now of special use to the descendants of this form--either directly, or indirectly, through the complex laws of growth." But it is one thing to say, Darwinically, that every detail observed in an animal's structure is of use to it, or has been of use to its ancestors; and quite another to affirm, teleologically, that every detail of an animal's structure has been created for its benefit. On the former hypothesis, for example, the teeth of the foetal _Balæna_ have a meaning; on the latter, none. So far as we are aware, there is not a phrase in the "Origin of Species," inconsistent with Professor Kölliker's position, that "varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent." On the contrary, Mr. Darwin writes (Summary of Chap. V.):-- "Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part varies more or less from the same part in the parents.... The external conditions of life, as climate and food, &c. seem to have induced some slight modifications. Habit, in producing constitutional differences, and use, in strengthening, and disuse, in weakening and diminishing organs, seem to have been more potent in their effects." And finally, as if to prevent all possible misconception, Mr. Darwin concludes his Chapter on Variation with these pregnant words:-- "Whatever the cause may be of each slight difference in the offspring from their parents--and a cause for each must exist--it is the steady accumulation, through natural selection of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure, by which the innumerable beings on the face of the earth are enabled to struggle with each other, and the best adapted to survive." We have dwelt at length upon this subject, because of its great general importance, and because we believe that Professor Kölliker's criticisms on this head are based upon a misapprehension of Mr. Darwin's views--substantially they appear to us to coincide with his own. The other objections which Professor Kölliker enumerates and discusses are the following:[66]-- "1. No transitional forms between existing species are known; and known varieties, whether selected or spontaneous, never go so far as to establish new species." To this Professor Kölliker appears to attach some weight. He makes the suggestion that the short-faced tumbler pigeon may be a pathological product. "2. No transitional forms of animals are met with among the organic remains of earlier epochs." Upon this, Professor Kölliker remarks that the absence of transitional forms in the fossil world, though not necessarily fatal to Darwin's views, weakens his case. "3. The struggle for existence does not take place." To this objection, urged by Pelzeln, Kölliker, very justly, attaches no weight. "4. A tendency of organisms to give rise to useful varieties, and a natural selection, do not exist. "The varieties which are found arise in consequence of manifold external influences, and it is not obvious why they all, or partially, should be particularly useful. Each animal suffices for its own ends, is perfect of its kind, and needs no further development. Should, however, a variety be useful and even maintain itself, there is no obvious reason why it should change any further. The whole conception of the imperfection of organisms and the necessity of their becoming perfected is plainly the weakest side of Darwin's Theory, and a _pis aller_ (Nothbehelf) because Darwin could think of no other principle by which to explain the metamorphoses which, as I also believe, have occurred." Here again we must venture to dissent completely from Professor Kölliker's conception of Mr. Darwin's hypothesis. It appears to us to be one of the many peculiar merits of that hypothesis that it involves no belief in a necessary and continual progress of organisms. Again, Mr. Darwin, if we read him aright, assumes no special tendency of organisms to give rise to useful varieties, and knows nothing of needs of development, or necessity of perfection. What he says is, in substance: All organisms vary. It is in the highest degree improbable that any given variety should have exactly the same relations to surrounding conditions as the parent stock. In that case it is either better fitted (when the variation may be called useful), or worse fitted, to cope with them. If better, it will tend to supplant the parent stock; if worse, it will tend to be extinguished by the parent stock. If (as is hardly conceivable) the new variety is so perfectly adapted to the conditions that no improvement upon it is possible,--it will persist, because, though it does not cease to vary, the varieties will be inferior to itself. If, as is more probable, the new variety is by no means perfectly adapted to its conditions, but only fairly well adapted to them, it will persist, so long as none of the varieties which it throws off are better adapted than itself. On the other hand, as soon as it varies in a useful way, _i.e._ when the variation is such as to adapt it more perfectly to its conditions, the fresh variety will tend to supplant the former. So far from a gradual progress towards perfection forming any necessary part of the Darwinian creed, it appears to us that it is perfectly consistent with indefinite persistence in one state, or with a gradual retrogression. Suppose, for example, a return of the glacial epoch and a spread of polar climatal conditions over the whole globe. The operation of natural selection under these circumstances would tend, on the whole, to the weeding out of the higher organisms and the cherishing of the lower forms of life. Cryptogamic vegetation would have the advantage over Phanerogamic; _Hydrozoa_ over Corals; _Crustacea_ over _Insecta_, and _Amphipoda_ and _Isopoda_ over the higher _Crustacea_; Cetaceans and Seals over the _Primates_; the civilization of the Esquimaux over that of the European. "5. Pelzeln has also objected that if the later organisms have proceeded from the earlier, the whole developmental series, from the simplest to the highest, could not now exist; in such a case the simpler organisms must have disappeared." To this Professor Kölliker replies, with perfect justice, that the conclusion drawn by Pelzeln does not really follow from Darwin's premises, and that, if we take the facts of Palæontology as they stand, they rather support than oppose Darwin's theory. "6. Great weight must be attached to the objection brought forward by Huxley, otherwise a warm supporter of Darwin's hypothesis, that we know of no varieties which are sterile with one another, as is the rule among sharply distinguished animal forms. "If Darwin is right, it must be demonstrated that forms may be produced by selection, which, like the present sharply distinguished animal forms, are infertile when coupled with one another, and this has not been done." The weight of this objection is obvious; but our ignorance of the conditions of fertility and sterility, the want of carefully conducted experiments extending over long series of years, and the strange anomalies presented by the results of the cross-fertilization of many plants, should all, as Mr. Darwin has urged, be taken into account in considering it. The seventh objection is that we have already discussed (_suprà_, p. 329). The eighth and last stands as follows:-- "8. The developmental theory of Darwin is not needed to enable us to understand the regular harmonious progress of the complete series of organic forms from the simpler to the more perfect. "The existence of general laws of Nature explains this harmony, even if we assume that all beings have arisen separately and independent of one another. Darwin forgets that inorganic nature, in which there can be no thought of a genetic connexion of forms, exhibits the same regular plan, the same harmony, as the organic world; and that, to cite only one example, there is as much a natural system of minerals as of plants and animals." We do not feel quite sure that we seize Professor Kölliker's meaning here, but he appears to suggest that the observation of the general order and harmony which pervade inorganic nature, would lead us to anticipate a similar order and harmony in the organic world. And this is no doubt true, but it by no means follows that the particular order and harmony observed among them should be that which we see. Surely the stripes of dun horses, and the teeth of the foetal _Balæna_, are not explained by the "existence of general laws of Nature." Mr. Darwin endeavours to explain the exact order of organic nature which exists; not the mere fact that there is some order. And with regard to the existence of a natural system of minerals; the obvious reply is that there may be a natural classification of any objects--of stones on a sea-beach, or of works of art; a natural classification being simply an assemblage of objects in groups, so as to express their most important and fundamental resemblances and differences. No doubt Mr. Darwin believes that those resemblances and differences upon which our natural systems or classifications of animals and plants are based, are resemblances and differences which have been produced genetically, but we can discover no reason for supposing that he denies the existence of natural classifications of other kinds. And, after all, is it quite so certain that a genetic relation may not underlie the classification of minerals? The inorganic world has not always been what we see it. It has certainly had its metamorphoses, and, very probably, a long "Entwickelungsgeschichte" out of a nebular blastema. Who knows how far that amount of likeness among sets of minerals, in virtue of which they are now grouped into families and orders, may not be the expression of the common conditions to which that particular patch of nebulous fog, which may have been constituted by their atoms, and of which they may be, in the strictest sense, the descendants, was subjected? It will be obvious from what has preceded, that we do not agree with Professor Kölliker in thinking the objections which he brings forward so weighty as to be fatal to Darwin's view. But even if the case were otherwise, we should be unable to accept the "Theory of Heterogeneous Generation" which is offered as a substitute. That theory is thus stated:-- "The fundamental conception of this hypothesis is, that, under the influence of a general law of development, the germs of organisms produce others different from themselves. This might happen (1) by the fecundated ova passing, in the course of their development, under particular circumstances, into higher forms; (2) by the primitive and later organisms producing other organisms without fecundation, out of germs or eggs (Parthenogenesis)." In favour of this hypothesis, Professor Kölliker adduces the well-known facts of Agamogenesis, or "alternate generation;" the extreme dissimilarity of the males and females of many animals; and of the males, females, and neuters of those insects which live in colonies: and he defines its relations to the Darwinian theory as follows:-- "It is obvious that my hypothesis is apparently very similar to Darwin's, inasmuch as I also consider that the various forms of animals have proceeded directly from one another. My hypothesis of the creation of organisms by heterogeneous generation, however, is distinguished very essentially from Darwin's by the entire absence of the principle of useful variations and their natural selection; and my fundamental conception is this, that a great plan of development lies at the foundation of the origin of the whole organic world, impelling the simpler forms to more and more complex developments. How this law operates, what influences determine the development of the eggs and germs, and impel them to assume constantly new forms, I naturally cannot pretend to say; but I can at least adduce the great analogy of the alternation of generations. If a _Bipinnaria_, a _Brachialaria_, a _Pluteus_, is competent to produce the Echinoderm, which is so widely different from it; if a hydroid polype can produce the higher Medusa; if the vermiform Trematode 'nurse' can develop within itself the very unlike _Cercaria_, it will not appear impossible that the egg, or ciliated embryo, of a sponge, for once, under special conditions, might become a hydroid polype, or the embryo of a Medusa, an Echinoderm." It is obvious, from these extracts, that Professor Kölliker's hypothesis is based upon the supposed existence of a close analogy between the phænomena of Agamogenesis and the production of new species from pre-existing ones. But is the analogy a real one? We think that it is not, and, by the hypothesis, cannot be. For what are the phænomena of Agamogenesis, stated generally? An impregnated egg develops into an asexual form, A; this gives rise, asexually, to a second form or forms, B, more or less different from A. B may multiply asexually again; in the simpler cases, however, it does not, but, acquiring sexual characters, produces impregnated eggs from whence A once more arises. No case of Agamogenesis is known in which, _when A differs widely from B_, it is itself capable of sexual propagation. No case whatever is known in which the progeny of B, by sexual generation, is other than a reproduction of A. But if this be a true statement of the nature of the process of Agamogenesis, how can it enable us to comprehend the production of new species from already existing ones? Let us suppose Hyænas to have preceded Dogs, and to have produced the latter in this way. Then the Hyæna will represent A, and the Dog, B. The first difficulty that presents itself is that the Hyæna must be asexual, or the process will be wholly without analogy in the world of Agamogenesis. But passing over this difficulty, and supposing a male and female Dog to be produced at the same time from the Hyæna stock, the progeny of the pair, if the analogy of the simpler kinds of Agamogenesis[67] is to be followed, should be a litter, not of puppies, but of young Hyænas. For the Agamogenetic series is always, as we have seen, A: B: A: B, &c.; whereas, for the production of a new species, the series must be A: B: B: B, &c. The production of new species, or genera, is the extreme permanent divergence from the primitive stock. All known Agamogenetic processes, on the other hand, end in a complete return to the primitive stock. How then is the production of new species to be rendered intelligible by the analogy of Agamogenesis? The other alternative put by Professor Kölliker--the passage of fecundated ova in the course of their development into higher forms--would, if it occurred, be merely an extreme case of variation in the Darwinian sense, greater in degree than, but perfectly similar in kind to, that which occurred when the well-known Ancon Ram was developed from an ordinary Ewe's ovum. Indeed we have always thought that Mr. Darwin has unnecessarily hampered himself by adhering so strictly to his favourite "Natura non facit saltum." We greatly suspect that she does make considerable jumps in the way of variation now and then, and that these saltations give rise to some of the gaps which appear to exist in the series of known forms. Strongly and freely as we have ventured to disagree with Professor Kölliker, we have always done so with regret, and we trust without violating that respect which is due, not only to his scientific eminence and to the careful study which he has devoted to the subject, but to the perfect fairness of his argumentation, and the generous appreciation of the worth of Mr. Darwin's labours which he always displays. It would be satisfactory to be able to say as much for M. Flourens. But the Perpetual Secretary of the French Academy of Sciences deals with Mr. Darwin as the first Napoleon would have treated an "idéologue;" and while displaying a painful weakness of logic and shallowness of information, assumes a tone of authority, which always touches upon the ludicrous, and sometimes passes the limits of good breeding. For example (p. 56):-- "M. Darwin continue: 'Aucune distinction absolue n'a été et ne peut être établie entre les espèces et les variétés.' Je vous ai déjà dit que vous vous trompiez; une distinction absolue sépare les variétés d'avec les espèces." "_Je vous ai déjà dit_; moi, M. le Secrétaire perpétuel de l'Académie des Sciences: et vous 'Qui n'êtes rien, Pas même Académicien;' what do you mean by asserting the contrary?" Being devoid of the blessings of an Academy in England, we are unaccustomed to see our ablest men treated in this fashion even by a "Perpetual Secretary." Or again, considering that if there is any one quality of Mr. Darwin's work to which friends and foes have alike borne witness, it is his candour and fairness in admitting and discussing objections, what is to be thought of M. Flourens' assertion, that "M. Darwin ne cite que les auteurs qui partagent ses opinions." (P. 40.) Once more (p. 65): "Enfin l'ouvrage de M. Darwin a paru. On ne peut qu'être frappé du talent de l'auteur. Mais que d'idées obscures, que d'idées fausses! Quel jargon métaphysique jeté mal à propos dans l'histoire naturelle, qui tombe dans le galimatias dès qu'elle sort des idées claires, des idées justes! Quel langage prétentieux et vide! Quelles personifications puériles et surannées! O lucidité! O solidité de l'esprit Français, que devenez-vous?" "Obscure ideas," "metaphysical jargon," "pretentious and empty language," "puerile and superannuated personifications." Mr. Darwin has many and hot opponents on this side of the Channel and in Germany, but we do not recollect to have found precisely these sins in the long catalogue of those hitherto laid to his charge. It is worth while, therefore, to examine into these discoveries effected solely by the aid of the "lucidity and solidity" of the mind of M. Flourens. According to M. Flourens, Mr. Darwin's great error is that he has personified Nature (p. 10), and further that he has "imagined a natural selection: he imagines afterwards that this power of selecting (_pouvoir d'élire_) which he gives to Nature is similar to the power of man. These two suppositions admitted, nothing stops him: he plays with Nature as he likes, and makes her do all he pleases." (P. 6.) And this is the way M. Flourens extinguishes natural selection: "Voyons donc encore une fois, ce qu'il peut y avoir de fondé dans ce qu'on nomme _élection naturelle_. "_L'élection naturelle_ n'est sous un autre nom que la nature. Pour un être organísé, la nature n'est que l'organisation, ni plus ni moins. "Il faudra donc aussi personnifier _l'organisation_, et dire que _l'organisation_ choisit _l'organisation_. _L'election naturelle_ est cette _forme substantielle_ dont on jonait autrefois avec tant de facilité. Aristote disait que 'Si l'art de bâtir était dans le bois, cet art agirait comme la nature.' A la place de _l'art de bâtir_ M. Darwin met _l'election naturelle_, et c'est tout un: l'un n'est pas plus chimérique que l'autre." (P. 31.) And this is really all that M. Flourens can make of Natural Selection. We have given the original, in fear lest a translation should be regarded as a travesty; but with the original before the reader, we may try to analyse the passage. "For an organized being, Nature is only organization, neither more nor less." Organized beings then have absolutely no relation to inorganic nature: a plant does not depend on soil or sunshine, climate, depth in the ocean, height above it; the quantity of saline matters in water have no influence upon animal life; the substitution of carbonic acid for oxygen in our atmosphere would hurt nobody! That these are absurdities no one should know better than M. Flourens; but they are logical deductions from the assertion just quoted, and from the further statement that natural selection means only that "organization chooses and selects organization." For if it be once admitted (what no sane man denies) that the chances of life of any given organism are increased by certain conditions (A) and diminished by their opposites (B), then it is mathematically certain that any change of conditions in the direction of (A) will exercise a selective influence in favour of that organism, tending to its increase and multiplication, while any change in the direction of (B) will exercise a selective influence against that organism, tending to its decrease and extinction. Or, on the other hand, conditions remaining the same, let a given organism vary (and no one doubts that they do vary) in two directions: into one form (a) better fitted to cope with these conditions than the original stock, and a second (b) less well adapted to them. Then it is no less certain that the conditions in question must exercise a selective influence in favour of (a) and against (b), so that (a) will tend to predominance, and (b) to extirpation. That M. Flourens should be unable to perceive the logical necessity of these simple arguments, which lie at the foundation of all Mr. Darwin's reasoning; that he should confound an irrefragable deduction from the observed relations of organisms to the conditions which lie around them, with a metaphysical "forme substantielle," or a chimerical personification of the powers of Nature, would be incredible, were it not that other passages of his work leave no room for doubt upon the subject. "On imagine une _élection naturelle_ que, pour plus de ménagement, on me dit être _inconsciente_, sans s'apercevoir que le contre-sens littéral est précisément là: _élection inconsciente_." (P. 52.) "J'ai déjà dit ce qu'il faut penser de _l'élection naturelle_. Ou _l'élection naturelle_ n'est rien, ou c'est la nature: mais la nature douée _d'élection_, mais la nature personnifiée: dernière erreur du dernier siècle: Le xix^e ne fait plus de personnifications." (P. 53.) M. Flourens cannot imagine an unconscious selection--it is for him a contradiction in terms. Did M. Flourens ever visit one of the prettiest watering-places of "la belle France," the Baie d'Arcachon? If so, he will probably have passed through the district of the Landes, and will have had an opportunity of observing the formation of "dunes" on a grand scale. What are these "dunes?" The winds and waves of the Bay of Biscay have not much consciousness, and yet they have with great care "selected," from among an infinity of masses of silex of all shapes and sizes, which have been submitted to their action, all the grains of sand below a certain size, and have heaped them by themselves over a great area. This sand has been "unconsciously selected" from amidst the gravel in which it first lay with as much precision as if man had "consciously selected" it by the aid of a sieve. Physical Geology is full of such selections--of the picking out of the soft from the hard, of the soluble from the insoluble, of the fusible from the infusible, by natural agencies to which we are certainly not in the habit of ascribing consciousness. But that which wind and sea are to a sandy beach, the sum of influences, which we term the "conditions of existence," is to living organisms. The weak are sifted out from the strong. A frosty night "selects" the hardy plants in a plantation from among the tender ones as effectually as if it were the wind, and they, the sand and pebbles, of our illustration; or, on the other hand, as if the intelligence of a gardener had been operative in cutting the weaker organisms down. The thistle, which has spread over the Pampas, to the destruction of native plants, has been more effectually "selected" by the unconscious operation of natural conditions than if a thousand agriculturists had spent their time in sowing it. It is one of Mr. Darwin's many great services to Biological science that he has demonstrated the significance of these facts. He has shown that--given variation and given change of conditions--the inevitable result is the exercise of such an influence upon organisms that one is helped and another is impeded; one tends to predominate, another to disappear; and thus the living world bears within itself, and is surrounded by, impulses towards incessant change. But the truths just stated are as certain as any other physical laws, quite independently of the truth, or falsehood, of the hypothesis which Mr. Darwin has based upon them; and that M. Flourens, missing the substance and grasping at a shadow, should be blind to the admirable exposition of them, which Mr. Darwin has given, and see nothing there but a "dernière erreur du dernier siècle"--a personification of Nature--leads us indeed to cry with him: "O lucidité! O solidité de l'esprit Français, que devenez-vous?" M. Flourens has, in fact, utterly failed to comprehend the first principles of the doctrine which he assails so rudely. His objections to details are of the old sort, so battered and hackneyed on this side of the Channel, that not even a Quarterly Reviewer could be induced to pick them up for the purpose of pelting Mr. Darwin over again. We have Cuvier and the mummies; M. Roulin and the domesticated animals of America; the difficulties presented by hybridism and by Palæontology; Darwinism a _rifacciamento_ of De Maillet and Lamarck; Darwinism a system without a commencement, and its author bound to believe in M. Pouchet, &c. &c. How one knows it all by heart, and with what relief one reads at p. 65-- "Je laisse M. Darwin!" But we cannot leave M. Flourens without calling our readers' attention to his wonderful tenth chapter, "De la Préexistence des Germes et de l'Epigénèse," which opens thus:-- "Spontaneous generation is only a chimæra. This point established, two hypotheses remain: that of _pre-existence_ and that of _epigenesis_. The one of these hypotheses has as little foundation as the other." (P. 163.) "The doctrine of _epigenesis_ is derived from Harvey: following by ocular inspection the development of the new being in the Windsor does, he saw each part appear successively, and taking the moment of _appearance_ for the moment of _formation_ he imagined _epigenesis_." (P. 165.) On the contrary, says M. Flourens (p. 167), "The new being is formed at a stroke (_tout d'un coup_), as a whole, instantaneously; it is not formed part by part, and at different times. It is formed at once; it is formed at the single _individual_ moment at which the conjunction of the male and female elements takes place." It will be observed that M. Flourens uses language which cannot be mistaken. For him, the labours of Von Baer, of Rathke, of Coste, and their contemporaries and successors in Germany, France, and England, are non-existent; and, as Darwin "_imagina_" natural selection, so Harvey "_imagina_" that doctrine which gives him an even greater claim to the veneration of posterity than his better known discovery of the circulation of the blood. Language such as that we have quoted is, in fact, so preposterous, so utterly incompatible with anything but absolute ignorance of some of the best established facts, that we should have passed it over in silence had it not appeared to afford some clue to M. Flourens' unhesitating, _à priori_, repudiation of all forms of the doctrine of the progressive modification of living beings. He whose mind remains uninfluenced by an acquaintance with the phænomena of development, must indeed lack one of the chief motives towards the endeavour to trace a genetic relation between the different existing forms of life. Those who are ignorant of Geology, find no difficulty in believing that the world was made as it is; and the shepherd, untutored in history, sees no reason to regard the green mounds which indicate the site of a Roman camp, as aught but part and parcel of the primæval hill-side. So M. Flourens, who believes that embryos are formed "tout d'un coup," naturally finds no difficulty in conceiving that species came into existence in the same way. FOOTNOTES: [65] "Die Radiolarien: eine Monographie," p. 231. [66] Space will not allow us to give Professor Kölliker's arguments in detail; our readers will find a full and accurate version of them in the _Reader_ for August 13th and 20th, 1864. [67] If, on the contrary, we follow the analogy of the more complex forms of Agamogenesis, such as that exhibited by some _Trematoda_ and by the _Aphides_, the Hyæna must produce, asexually, a brood of asexual Dogs, from which other sexless Dogs must proceed. At the end of a certain number of terms of the series, the Dogs would acquire sexes and generate young; but these young would be, not Dogs, but Hyænas. In fact, we have _demonstrated_, in Agamogenetic phænomena, that inevitable recurrence to the original type, which is _asserted_ to be true of variations in general, by Mr. Darwin's opponents; and which, if the assertion could be changed into a demonstration, would, in fact, be fatal to his hypothesis. XIV. ON DESCARTES' "DISCOURSE TOUCHING THE METHOD OF USING ONE'S REASON RIGHTLY AND OF SEEKING SCIENTIFIC TRUTH." It has been well said that "all the thoughts of men, from the beginning of the world until now, are linked together into one great chain;" but the conception of the intellectual filiation of mankind which is expressed in these words may, perhaps, be more fitly shadowed forth by a different metaphor. The thoughts of men seem rather to be comparable to the leaves, flowers, and fruit upon the innumerable branches of a few great stems, fed by commingled and hidden roots. These stems bear the names of the half-a-dozen men, endowed with intellects of heroic force and clearness, to whom we are led, at whatever point of the world of thought the attempt to trace its history commences; just as certainly as the following up the small twigs of a tree to the branchlets which bear them, and tracing the branchlets to their supporting branches, brings us, sooner or later, to the bole. It seems to me that the thinker who, more than any other, stands in the relation of such a stem towards the philosophy and the science of the modern world is René Descartes. I mean, that if you lay hold of any characteristic product of modern ways of thinking, either in the region of philosophy, or in that of science, you find the spirit of that thought, if not its form, to have been present in the mind of the great Frenchman. There are some men who are counted great because they represent the actuality of their own age, and mirror it as it is. Such an one was Voltaire, of whom it was epigrammatically said, "he expressed everybody's thoughts better than anybody."[68] But there are other men who attain greatness because they embody the potentiality of their own day, and magically reflect the future. They express the thoughts which will be everybody's two or three centuries after them. Such an one was Descartes. Born, in 1596, nearly three hundred years ago, of a noble family in Touraine, René Descartes grew up into a sickly and diminutive child, whose keen wit soon gained him that title of "the Philosopher," which, in the mouths of his noble kinsmen, was more than, half a reproach. The best schoolmasters of the day, the Jesuits, educated him as well as a French boy of the seventeenth century could be educated. And they must have done their work honestly and well, for, before his schoolboy days were over, he had discovered that the most of what he had learned, except in mathematics, was devoid of solid and real value. "Therefore," says he, in that "Discourse"[69] which I have taken for my text, "as soon as I was old enough to be set free from the government of my teachers, I entirely forsook the study of letters; and determining to seek no other knowledge than that which I could discover within myself, or in the great book of the world, I spent the remainder of my youth in travelling; in seeing courts and armies; in the society of people of different humours and conditions; in gathering varied experience; in testing myself by the chances of fortune; and in always trying to profit by my reflections on what happened.... And I always had an intense desire to learn how to distinguish truth from falsehood, in order to be clear about my actions, and to walk surefootedly in this life." But "learn what is true, in order to do what is right," is the summing up of the whole duty of man, for all who are unable to satisfy their mental hunger with the east wind of authority; and to those of us moderns who are in this position, it is one of Descartes' great claims to our reverence as a spiritual ancestor, that, at three-and-twenty, he saw clearly that this was his duty, and acted up to his conviction. At two-and-thirty, in fact, finding all other occupations incompatible with the search after the knowledge which leads to action, and being possessed of a modest competence, he withdrew into Holland; where he spent nine years in learning and thinking, in such retirement that only one or two trusted friends knew of his whereabouts. In 1637 the firstfruits of these long meditations were given to the world in the famous "Discourse touching the Method of using Reason rightly and of seeking scientific Truth," which, at once an autobiography and a philosophy, clothes the deepest thought in language of exquisite harmony, simplicity, and clearness. The central propositions of the whole "Discourse" are these. There is a path that leads to truth so surely, that if any one who will follow it must needs reach the goal, whether his capacity be great or small. And there is one guiding rule by which a man may always find this path, and keep himself from straying when he has found it. This golden rule is--give unqualified assent to no propositions but those the truth of which is so clear and distinct that they cannot be doubted. The enunciation of this great first commandment of science consecrated Doubt. It removed Doubt from the seat of penance among the grievous sins to which it had long been condemned, and enthroned it in that high place among the primary duties, which is assigned to it by the scientific conscience of these latter days. Descartes was the first among the moderns to obey this commandment deliberately; and, as a matter of religious duty, to strip off all his beliefs and reduce himself to a state of intellectual nakedness, until such time as he could satisfy himself which were fit to be worn. He thought a bare skin healthier than the most respectable and well-cut clothing of what might, possibly, be mere shoddy. When I say that Descartes consecrated doubt, you must remember that it was that sort of doubt which Goethe has called "the active scepticism, whose whole aim is to conquer itself;"[70] and not that other sort which is born of flippancy and ignorance, and whose aim is only to perpetuate itself, as an excuse for idleness and indifference. But it is impossible to define what is meant by scientific doubt better than in Descartes' own words. After describing the gradual progress of his negative criticism, he tells us:-- "For all that, I did not imitate the sceptics, who doubt only for doubting's sake, and pretend to be always undecided; on the contrary, my whole intention was to arrive at certainty, and to dig away the drift and the sand until I reached the rock or the clay beneath." And further, since no man of common sense, when he pulls down his house for the purpose of rebuilding it, fails to provide himself with some shelter while the work is in progress; so, before demolishing the spacious, if not commodious, mansion of his old beliefs, Descartes thought it wise to equip himself with what he calls "_une morale par provision_," by which he resolved to govern his practical life until such time as he should be better instructed. The laws of this "provisional self-government" are embodied in four maxims, of which one binds our philosopher to submit himself to the laws and religion in which he was brought up; another, to act, on all those occasions which call for action, promptly and according to the best of his judgment, and to abide, without repining, by the result: a third rule is to seek happiness in limiting his desires, rather than in attempting to satisfy them; while the last is to make the search after truth the business of his life. Thus prepared to go on living while he doubted, Descartes proceeded to face his doubts like a man. One thing was clear to him, he would not lie to himself--would, under no penalties, say, "I am sure" of that of which he was not sure; but would go on digging and delving until he came to the solid adamant; or, at worst, made sure there was no adamant. As the record of his progress tells us, he was obliged to confess that life is full of delusions; that authority may err; that testimony may be false or mistaken; that reason lands us in endless fallacies; that memory is often as little trustworthy as hope; that the evidence of the very senses may be misunderstood; that dreams are real as long as they last, and that what we call reality may be a long and restless dream. Nay, it is conceivable that some powerful and malicious being may find his pleasure in deluding us, and in making us believe the thing which is not, every moment of our lives. What, then, is certain? What even, if such a being exists, is beyond the reach of his powers of delusion? Why, the fact that the thought, the present consciousness, exists. Our thoughts may be delusive, but they cannot be fictitious. As thoughts, they are real and existent, and the cleverest deceiver cannot make them otherwise. Thus, thought is existence. More than that, so far as we are concerned, existence is thought, all our conceptions of existence being some kind or other of thought. Do not for a moment suppose that these are mere paradoxes or subtleties. A little reflection upon the commonest facts proves them to be irrefragable truths. For example, I take up a marble, and I find it to be a red, round, hard, single body. We call the redness, the roundness, the hardness, and the singleness, "qualities" of the marble; and it sounds, at first, the height of absurdity to say that all these qualities are modes of our own consciousness, which cannot even be conceived to exist in the marble. But consider the redness, to begin with. How does the sensation of redness arise? The waves of a certain very attenuated matter, the particles of which are vibrating with vast rapidity, but with very different velocities, strike upon the marble, and those which vibrate with one particular velocity are thrown off from its surface in all directions. The optical apparatus of the eye gathers some of these together, and gives them such a course that they impinge upon the surface of the retina, which is a singularly delicate apparatus, connected with the termination of the fibres of the optic nerve. The impulses of the attenuated matter, or ether, affect this apparatus and the fibres of the optic nerve in a certain way; and the change in the fibres of the optic nerve produces yet other changes in the brain; and these, in some fashion unknown to us, give rise to the feeling, or consciousness, of redness. If the marble could remain unchanged, and either the rate of vibration of the ether, or the nature of the retina, could be altered, the marble would seem not red, but some other colour. There are many people who are what are called colourblind, being unable to distinguish one colour from another. Such an one might declare our marble to be green; and he would be quite as right in saying that it is green, as we are in declaring it to be red. But then, as the marble cannot, in itself, be both green and red, at the same time, this shows that the quality "redness" must be in our consciousness and not in the marble. In like manner, it is easy to see that the roundness and the hardness are forms of our consciousness, belonging to the groups which we call sensations of sight and touch. If the surface of the cornea were cylindrical, we should have a very different notion of a round body from that which we possess now; and if the strength of the fabric, and the force of the muscles, of the body were increased a hundredfold, our marble would seem to be as soft as a pellet of bread crumbs. Not only is it obvious that all these qualities are in us, but, if you will make the attempt, you will find it quite impossible to conceive of "blueness," "roundness," and "hardness" as existing without reference to some such consciousness as our own. It may seem strange to say that even the "singleness" of the marble is relative to us; but extremely simple experiments will show that such is veritably the case, and that our two most trustworthy senses may be made to contradict one another on this very point. Hold the marble between the finger and thumb, and look at it in the ordinary way. Sight and touch agree that it is single. Now squint, and sight tells you that there are two marbles, while touch asserts that there is only one. Next, return the eyes to their natural position, and, having crossed the forefinger and the middle finger, put the marble between their tips. Then touch will declare that there are two marbles, while sight says that there is only one; and touch claims our belief, when we attend to it, just as imperatively as sight does. But it may be said, the marble takes up a certain space which could not be occupied, at the same time, by anything else. In other words, the marble has the primary quality of matter, extension. Surely this quality must be in the thing, and not in our minds? But the reply must still be; whatever may, or may not, exist in the thing, all that we can know of these qualities is a state of consciousness. What we call extension is a consciousness of a relation between two, or more, affections of the sense of sight, or of touch. And it is wholly inconceivable that what we call extension should exist independently of such consciousness as our own. Whether, notwithstanding this inconceivability, it does so exist, or not, is a point on which I offer no opinion. Thus, whatever our marble may be in itself, all that we can know of it is under the shape of a bundle of our own consciousnesses. Nor is our knowledge of anything we know or feel more, or less, than a knowledge of states of consciousness. And our whole life is made up of such states. Some of these states we refer to a cause we call "self;" others to a cause or causes which may be comprehended under the title of "not-self." But neither of the existence of "self," nor of that of "not-self," have we, or can we by any possibility have, any such unquestionable and immediate certainty as we have of the states of consciousness which we consider to be their effects. They are not immediately observed facts, but results of the application of the law of causation to those facts. Strictly speaking, the existence of a "self" and of a "not-self" are hypotheses by which we account for the facts of consciousness. They stand upon the same footing as the belief in the general trustworthiness of memory, and in the general constancy of the order of nature--as hypothetical assumptions which cannot be proved, or known with that highest degree of certainty which is given by immediate consciousness; but which, nevertheless, are of the highest practical value, inasmuch as the conclusions logically drawn from them are always verified by experience. This, in my judgment, is the ultimate issue of Descartes' argument; but it is proper for me to point out that we have left Descartes himself some way behind us. He stopped at the famous formula, "I think, therefore I am." But a little consideration will show this formula to be full of snares and verbal entanglements. In the first place, the "therefore" has no business there. The "I am" is assumed in the "I think," which is simply another way of saying "I am thinking." And, in the second place, "I think" is not one simple proposition, but three distinct assertions rolled into one. The first of these is, "something called I exists;" the second is, "something called thought exists;" and the third is, "the thought is the result of the action of the I." Now, it will be obvious to you, that the only one of these three propositions which can stand the Cartesian test of certainty is the second. It cannot be doubted, for the very doubt is an existent thought. But the first and third, whether true or not, may be doubted, and have been doubted. For the assertor may be asked, How do you know that thought is not self-existent; or that a given thought is not the effect of its antecedent thought, or of some external power? And a diversity of other questions, much more easily put than answered. Descartes, determined as he was to strip off all the garments which the intellect weaves for itself, forgot this gossamer shirt of the "self;" to the great detriment, and indeed ruin, of his toilet when he began to clothe himself again. But it is beside my purpose to dwell upon the minor peculiarities of the Cartesian philosophy. All I wish to put clearly before your minds thus far, is that Descartes, having commenced by declaring doubt to be a duty, found certainty in consciousness alone; and that the necessary outcome of his views is what may properly be termed Idealism; namely, the doctrine that, whatever the universe may be, all we can know of it is the picture presented to us by consciousness. This picture may be a true likeness--though how this can be is inconceivable; or it may have no more resemblance to its cause than one of Bach's fugues has to the person who is playing it; or than a piece of poetry has to the mouth and lips of a reciter. It is enough for all the practical purposes of human existence if we find that our trust in the representations of consciousness is verified by results; and that, by their help, we are enabled "to walk surefootedly in this life." Thus the method, or path which leads to truth, indicated by Descartes, takes us straight to the Critical Idealism of his great successor Kant. It is that Idealism which declares the ultimate fact of all knowledge to be a consciousness, or, in other words, a mental phenomenon; and therefore affirms the highest of all certainties, and indeed the only absolute certainty, to be the existence of mind. But it is also that Idealism which refuses to make any assertions, either positive or negative, as to what lies beyond consciousness. It accuses the subtle Berkeley of stepping beyond the limits of knowledge when he declared that a substance of matter does not exist; and of illogicality, for not seeing that the arguments which he supposed demolished the existence of matter were equally destructive to the existence of soul. And it refuses to listen to the jargon of more recent days about the "Absolute," and all the other hypostatized adjectives, the initial letters of the names of which are generally printed in capital letters; just as you give a Grenadier a bearskin cap, to make him look more formidable than he is by nature. I repeat, the path indicated and followed by Descartes which we have hitherto been treading, leads through doubt to that critical Idealism which lies at the heart of modern metaphysical thought. But the "Discourse" shows us another, and apparently very different, path, which leads, quite as definitely, to that correlation of all the phænomena of the universe with matter and motion, which lies at the heart of modern physical thought, and which most people call Materialism. The early part of the seventeenth century, when Descartes reached manhood, is one of the great epochs of the intellectual life of mankind. At that time, physical science suddenly strode into the arena of public and familiar thought, and openly challenged, not only Philosophy and the Church, but that common ignorance which passes by the name of Common Sense. The assertion of the motion of the earth was a defiance to all three, and Physical Science threw down her glove by the hand of Galileo. It is not pleasant to think of the immediate result of the combat; to see the champion of science, old, worn, and on his knees before the Cardinal Inquisitor, signing his name to what he knew to be a lie. And, no doubt, the Cardinals rubbed their hands as they thought how well they had silenced and discredited their adversary. But two hundred years have passed, and however feeble or faulty her soldiers, Physical Science sits crowned and enthroned as one of the legitimate rulers of the world of thought. Charity children would be ashamed not to know that the earth moves; while the Schoolmen are forgotten; and the Cardinals--well, the Cardinals are at the oecumenical Council, still at their old business of trying to stop the movement of the world. As a ship, which having lain becalmed with every stitch of canvas set, bounds away before the breeze which springs up astern, so the mind of Descartes, poised in equilibrium of doubt, not only yielded to the full force of the impulse towards physical science and physical ways of thought, given by his great contemporaries, Galileo and Harvey, but shot beyond them; and anticipated, by bold speculation, the conclusions, which could only be placed upon a secure foundation by the labours of generations of workers. Descartes saw that the discoveries of Galileo meant that the remotest parts of the universe were governed by mechanical laws; while those of Harvey meant that the same laws presided over the operations of that portion of the world which is nearest to us, namely, our own bodily frame. And crossing the interval between the centre and its vast circumference by one of the great strides of genius, Descartes sought to resolve all the phænomena of the universe into matter and motion, or forces operating according to law.[71] This grand conception, which is sketched in the "Discours," and more fully developed in the "Principes" and in the "Traité de l'Homme," he worked out with extraordinary power and knowledge; and with the effect of arriving, in the last-named essay, at that purely mechanical view of vital phænomena towards which modern physiology is striving. Let us try to understand how Descartes got into this path, and why it led him where it did. The mechanism of the circulation of the blood had evidently taken a great hold of his mind, as he describes it several times, at much length. After giving a full account of it in the "Discourse," and erroneously describing the motion of the blood, not to the contraction of the walls of the heart, but to the heat which he supposes to be generated there, he adds:-- "This motion, which I have just explained, is as much the necessary result of the structure of the parts which one can see in the heart, and of the heat which one may feel there with one's fingers, and of the nature of the blood, which may be experimentally ascertained; as is that of a clock of the force, the situation, and the figure, of its weight and of its wheels." But if this apparently vital operation were explicable as a simple mechanism, might not other vital operations be reducible to the same category? Descartes replies without hesitation in the affirmative. "The animal spirits," says he, "resemble a very subtle fluid, or a very pure and vivid flame, and are continually generated in the heart, and ascend to the brain as to a sort of reservoir. Hence they pass into the nerves and are distributed to the muscles, causing contraction, or relaxation, according to their quantity." Thus, according to Descartes, the animal body is an automaton, which is competent to perform all the animal functions in exactly the same way as a clock or any other piece of mechanism. As he puts the case himself:-- "In proportion as these spirits [the animal spirits] enter the cavities of the brain, they pass thence into the pores of its substance, and from these pores into the nerves; where, according as they enter, or even only tend to enter, more or less, into one than into another, they have the power of altering the figure of the muscles into which the nerves are inserted, and by this means of causing all the limbs to move. Thus, as you may have seen in the grottoes and the fountains in royal gardens, the force with which the water issues from its reservoir is sufficient to move various machines, and even to make them play instruments, or pronounce words according to the different disposition of the pipes which lead the water. "And, in truth, the nerves of the machine which I am describing may very well be compared to the pipes of these waterworks; its muscles and its tendons to the other various engines and springs which seem to move them; its animal spirits to the water which impels them, of which the heart is the fountain; while the cavities of the brain are the central office. Moreover, respiration and other such actions as are natural and usual in the body, and which depend on the course of the spirits, are like the movements of a clock, or of a mill, which may be kept up by the ordinary flow of the water. "The external objects which, by their mere presence, act upon the organs of the senses; and which, by this means, determine the corporal machine to move in many different ways, according as the parts of the brain are arranged, are like the strangers who, entering into some of the grottoes of these waterworks, unconsciously cause the movements which take place in their presence. For they cannot enter without treading upon certain planks so arranged that, for example, if they approach a bathing Diana, they cause her to hide among the reeds; and if they attempt to follow her, they see approaching a Neptune, who threatens them with his trident; or if they try some other way, they cause some monster who vomits water into their faces, to dart out; or like contrivances, according to the fancy of the engineers who have made them. And lastly, when the _rational soul_ is lodged in this machine, it will have its principal seat in the brain, and will take the place of the engineer, who ought to be in that part of the works with which all the pipes are connected, when he wishes to increase, or to slacken, or in some way to alter, their movements."[72] And again still more strongly:-- "All the functions which I have attributed to this machine (the body), as the digestion of food, the pulsation of the heart and of the arteries; the nutrition and the growth of the limbs; respiration, wakefulness, and sleep; the reception of light, sounds, odours, flavours, heat, and such like qualities, in the organs of the external senses; the impression of the ideas of these in the organ of common sense and in the imagination; the retention, or the impression, of these ideas on the memory; the internal movements of the appetites and the passions; and lastly, the external movements of all the limbs, which follow so aptly, as well the action of the objects which are presented to the senses, as the impressions which meet in the memory, that they imitate as nearly as possible those of a real man:[73] I desire, I say, that you should consider that these functions in the machine naturally proceed from the mere arrangement of its organs, neither more nor less than do the movements of a clock, or other automaton, from that of its weights and its wheels; so that, so far as these are concerned, it is not necessary to conceive any other vegetative or sensitive soul, nor any other principle of motion, or of life, than the blood and the spirits agitated by the fire which burns continually in the heart, and which is no wise essentially different from all the fires which exist in inanimate bodies."[74] The spirit of these passages is exactly that of the most advanced physiology of the present day; all that is necessary to make them coincide with our present physiology in form, is to represent the details of the working of the animal machinery in modern language, and by the aid of modern conceptions. Most undoubtedly, the digestion of food in the human body is a purely chemical process; and the passage of the nutritive parts of that food into the blood, a physical operation. Beyond all question, the circulation of the blood is simply a matter of mechanism, and results from the structure and arrangement of the parts of the heart and vessels, from the contractility of those organs, and from the regulation of that contractility by an automatically acting nervous apparatus. The progress of physiology has further shown, that the contractility of the muscles and the irritability of the nerves are purely the results of the molecular mechanism of those organs; and that the regular movements of the respiratory, alimentary, and other internal organs are governed and guided, as mechanically, by their appropriate nervous centres. The even rhythm of the breathing of every one of us depends upon the structural integrity of a particular region of the medulla oblongata, as much as the ticking of a clock depends upon the integrity of the escapement. You may take away the hands of a clock and break up its striking machinery, but it will still tick; and a man may be unable to feel, speak, or move, and yet he will breathe. Again, in entire accordance with Descartes' affirmation, it is certain that the modes of motion which constitute the physical basis of light, sound, and heat, are transmuted into affections of nervous matter by the sensory organs. These affections are, so to speak, a kind of physical ideas, which are retained in the central organs, constituting what might be called physical memory, and may be combined in a manner which answers to association and imagination, or may give rise to muscular contractions, in those "reflex actions" which are the mechanical representatives of volitions. Consider what happens when a blow is aimed at the eye.[75] Instantly, and without our knowledge or will, and even against the will, the eyelids close. What is it that happens? A picture of the rapidly advancing fist is made upon the retina at the back of the eye. The retina changes this picture into an affection of a number of the fibres of the optic nerve; the fibres of the optic nerve affect certain parts of the brain; the brain, in consequence, affects those particular fibres of the seventh nerve which go to the orbicular muscle of the eyelids; the change in these nerve-fibres causes the muscular fibres to change their dimensions, so as to become shorter and broader; and the result is the closing of the slit between the two lids, round which these fibres are disposed. Here is a pure mechanism, giving rise to a purposive action, and strictly comparable to that by which Descartes supposes his waterwork Diana to be moved. But we may go further, and inquire whether our volition, in what we term voluntary action, ever plays any other part than that of Descartes' engineer, sitting in his office, and turning this tap or the other, as he wishes to set one or another machine in motion, but exercising no direct influence upon the movements of the whole. Our voluntary acts consist of two parts: firstly, we desire to perform a certain action; and, secondly, we somehow set a-going a machinery which does what we desire. But so little do we directly influence that machinery, that nine-tenths of us do not even know its existence. Suppose one wills to raise one's arm and whirl it round. Nothing is easier. But the majority of us do not know that nerves and muscles are concerned in this process; and the best anatomist among us would be amazingly perplexed, if he were called upon to direct the succession, and the relative strength, of the multitudinous nerve-changes, which are the actual causes of this very simple operation. So again in speaking. How many of us know that the voice is produced in the larynx, and modified by the mouth? How many among these instructed persons understand how the voice is produced and modified? And what living man, if he had unlimited control over all the nerves supplying the mouth and larynx of another person, could make him pronounce a sentence? Yet, if one has anything to say, what is easier than to say it? We desire the utterance of certain words: we touch the spring of the word-machine, and they are spoken. Just as Descartes' engineer, when he wanted a particular hydraulic machine to play, had only to turn a tap, and what he wished was done. It is because the body is a machine that education is possible. Education is the formation of habits, a superinducing of an artificial organization upon the natural organization of the body; so that acts, which at first required a conscious effort, eventually became unconscious and mechanical. If the act which primarily requires a distinct consciousness and volition of its details, always needed the same effort, education would be an impossibility. According to Descartes, then, all the functions which are common to man and animals are performed by the body as a mere mechanism, and he looks upon consciousness as the peculiar distinction of the "_chose pensante_," of the "rational soul," which in man (and in man only, in Descartes' opinion) is superadded to the body. This rational soul he conceived to be lodged in the pineal gland, as in a sort of central office; and, here, by the intermediation of the animal spirits, it became aware of what was going on in the body, or influenced the operations of the body. Modern physiologists do not ascribe so exalted a function to the little pineal gland, but, in a vague sort of way, they adopt Descartes' principle, and suppose that the soul is lodged in the cortical part of the brain--at least this is commonly regarded as the seat and instrument of consciousness. Descartes has clearly stated what he conceived to be the difference between spirit and matter. Matter is substance which has extension, but does not think; spirit is substance which thinks, but has no extension. It is very hard to form a definite notion of what this phraseology means, when it is taken in connexion with the location of the soul in the pineal gland; and I can only represent it to myself as signifying that the soul is a mathematical point, having place but not extension, within the limits of the pineal gland. Not only has it place, but it must exert force; for, according to the hypothesis, it is competent, when it wills, to change the course of the animal spirits, which consist of matter in motion. Thus the soul becomes a centre of force. But, at the same time, the distinction between spirit and matter vanishes; inasmuch as matter, according to a tenable hypothesis, may be nothing but a multitude of centres of force. The case is worse if we adopt the modern vague notion that consciousness is seated in the grey matter of the cerebrum, generally; for, as the grey matter has extension, that which is lodged in it must also have extension. And thus we are led, in another way, to lose spirit in matter. In truth, Descartes' physiology, like the modern physiology of which it anticipates the spirit, leads straight to Materialism, so far as that title is rightly applicable to the doctrine that we have no knowledge of any thinking substance, apart from extended substance; and that thought is as much a function of matter as motion is. Thus we arrive at the singular result that, of the two paths opened up to us in the "Discourse upon Method," the one leads, by way of Berkeley and Hume, to Kant and Idealism; while the other leads, by way of De La Mettrie and Priestley, to modern physiology and Materialism.[76] Our stem divides into two main branches, which grow in opposite ways, and bear flowers which look as different as they can well be. But each branch is sound and healthy, and has as much life and vigour as the other. If a botanist found this state of things in a new plant, I imagine that he might be inclined to think that his tree was monoecious--that the flowers were of different sexes, and that, so far from setting up a barrier between the two branches of the tree, the only hope of fertility lay in bringing them together. I may be taking too much of a naturalist's view of the case, but I must confess that this is exactly my notion of what is to be done with metaphysics and physics. Their differences are complementary, not antagonistic; and thought will never be completely fruitful until the one unites with the other. Let me try to explain what I mean. I hold, with the Materialist, that the human body, like all living bodies, is a machine, all the operations of which will, sooner or later, be explained on physical principles. I believe that we shall, sooner or later, arrive at a mechanical equivalent of consciousness, just as we have arrived at a mechanical equivalent of heat. If a pound weight falling through a distance of a foot gives rise to a definite amount of heat, which may properly be said to be its equivalent; the same pound weight falling through a foot on a man's hand gives rise to a definite amount of feeling, which might with equal propriety be said to be its equivalent in consciousness.[77] And as we already know that there is a certain parity between the intensity of a pain and the strength of one's desire to get rid of that pain; and secondly, that there is a certain correspondence between the intensity of the heat, or mechanical violence, which gives rise to the pain, and the pain itself; the possibility of the establishment of a correlation between mechanical force and volition becomes apparent. And the same conclusion is suggested by the fact that, within certain limits, the intensity of the mechanical force we exert is proportioned to the intensity of our desire to exert it. Thus I am prepared to go with the Materialists wherever the true pursuit of the path of Descartes may lead them; and I am glad, on all occasions, to declare my belief that their fearless development of the materialistic aspect of these matters has had an immense, and a most beneficial, influence upon physiology and psychology. Nay more, when they go farther than I think they are entitled to do--when they introduce Calvinism into science and declare that man is nothing but a machine, I do not see any particular harm in their doctrines, so long as they admit that which is a matter of experimental fact--namely, that it is a machine capable of adjusting itself within certain limits. I protest that if some great Power would agree to make me always think what is true and do what is right, on condition of being turned into a sort of clock and wound up every morning before I got out of bed, I should instantly close with the offer. The only freedom I care about is the freedom to do right; the freedom to do wrong I am ready to part with on the cheapest terms to any one who will take it of me. But when the Materialists stray beyond the borders of their path and begin to talk about there being nothing else in the universe but Matter and Force and Necessary Laws, and all the rest of _their_ "grenadiers," I decline to follow them. I go back to the point from which we started, and to the other path of Descartes. I remind you that we have already seen clearly and distinctly, and in a manner which admits of no doubt, that all our knowledge is a knowledge of states of consciousness. "Matter" and "Force" are, so far as we can know, mere names for certain forms of consciousness. "Necessary" means that of which we cannot conceive the contrary. "Law" means a rule which we have always found to hold good, and which we expect always will hold good. Thus it is an indisputable truth that what we call the material world is only known to us under the forms of the ideal world; and, as Descartes tells us, our knowledge of the soul is more intimate and certain than our knowledge of the body. If I say that impenetrability is a property of matter, all that I can really mean is that the consciousness I call extension, and the consciousness I call resistance, constantly accompany one another. Why and how they are thus related is a mystery. And if I say that thought is a property of matter, all that I can mean is that, actually or possibly, the consciousness of extension and that of resistance accompany all other sorts of consciousness. But, as in the former case, why they are thus associated is an insoluble mystery. From all this it follows that what I may term legitimate materialism, that is, the extension of the conceptions and of the methods of physical science to the highest as well as the lowest phenomena of vitality, is neither more nor less than a sort of shorthand Idealism; and Descartes' two paths meet at the summit of the mountain, though they set out on opposite sides of it. The reconciliation of physics and metaphysics lies in the acknowledgment of faults upon both sides; in the confession by physics that all the phænomena of nature are, in their ultimate analysis, known to us only as facts of consciousness; in the admission by metaphysics, that the facts of consciousness are, practically, interpretable only by the methods and the formulæ of physics: and, finally, in the observance by both metaphysical and physical thinkers of Descartes' maxim--assent to no proposition the matter of which is not so clear and distinct that it cannot be doubted. When you did me the honour to ask me to deliver this address, I confess I was perplexed what topic to select. For you are emphatically and distinctly a _Christian_ body; while science and philosophy, within the range of which lie all the topics on which I could venture to speak, are neither Christian, nor Unchristian, but are Extrachristian, and have a world of their own, which, to use language which will be very familiar to your ears just now, is not only "unsectarian," but is altogether "secular." The arguments which I have put before you to-night, for example, are not inconsistent, so far as I know, with any form of theology. After much consideration, I thought that I might be most useful to you, if I attempted to give you some vision of this Extrachristian world, as it appears to a person who lives a good deal in it; and if I tried to show you by what methods the dwellers therein try to distinguish truth from falsehood, in regard to some of the deepest and most difficult problems that beset humanity, "in order to be clear about their actions, and to walk surefootedly in this life," as Descartes says. It struck me that if the execution of my project came anywhere near the conception of it, you would become aware that the philosophers and the men of science are not exactly what they are sometimes represented to you to be; and that their methods and paths do not lead so perpendicularly downwards as you are occasionally told they do. And I must admit, also, that a particular and personal motive weighed with me,--namely, the desire to show that a certain discourse, which brought a great storm about my head some time ago, contained nothing but the ultimate development of the views of the father of modern philosophy. I do not know if I have been quite wise in allowing this last motive to weigh with me. They say that the most dangerous thing one can do in a thunderstorm is to shelter oneself under a great tree, and the history of Descartes' life shows how narrowly he escaped being riven by the lightnings, which were more destructive in his time than in ours. Descartes lived and died a good Catholic, and prided himself upon having demonstrated the existence of God and of the soul of man. As a reward for his exertions, his old friends the Jesuits put his works upon the "Index," and called him an Atheist; while the Protestant divines of Holland declared him to be both a Jesuit and an Atheist. His books narrowly escaped being burned by the hangman; the fate of Vanini was dangled before his eyes; and the misfortunes of Galileo so alarmed him, that he well-nigh renounced the pursuits by which the world has so greatly benefited, and was driven into subterfuges and evasions which were not worthy of him. "Very cowardly," you may say; and so it was. But you must make allowance for the fact that, in the seventeenth century, not only did heresy mean possible burning, or imprisonment, but the very suspicion of it destroyed a man's peace, and rendered the calm pursuit of truth difficult or impossible. I fancy that Descartes was a man to care more about being worried and disturbed, than about being burned outright; and, like many other men, sacrificed for the sake of peace and quietness, what he would have stubbornly maintained against downright violence. However this may be, let those who are sure they would have done better throw stones at him. I have no feelings but those of gratitude and reverence for the man who did what he did, when he did; and a sort of shame that any one should repine against taking a fair share of such treatment as the world thought good enough for him. Finally, it occurs to me that, such being my feeling about the matter, it may be useful to all of us if I ask you, "What is yours? Do you think that the Christianity of the seventeenth century looks nobler and more attractive for such treatment of such a man?" You will hardly reply that it does. But if it does not, may it not be well if all of you do what lies within your power to prevent the Christianity of the nineteenth century from repeating the scandal? There are one or two living men, who, a couple of centuries hence, will be remembered as Descartes is now, because they have produced great thoughts which will live and grow as long as mankind lasts. If the twenty-first century studies their history, it will find that the Christianity of the middle of the nineteenth century recognised them only as objects of vilification. It is for you and such as you, Christian young men, to say whether this shall be as true of the Christianity of the future as it is of that of the present. I appeal to you to say "No," in your own interest, and in that of the Christianity you profess. In the interest of Science, no appeal is needful; as Dante sings of Fortune-- "Quest' è colei, ch'è tanto posta in croce Pur da color, che le dovrian dar lode Dandole biasmo a torto e mala voce. Ma ella s' è beata, e ciò non ode: Con l' altre prime creature lieta Volve sua spera, e beata si gode:"[78] so, whatever evil voices may rage, Science, secure among the powers that are eternal, will do her work and be blessed. FOOTNOTES: [68] I forget who it was said of him: "Il a plus que personne l'esprit que tout le monde a." [69] "Discours de la Méthode pour bien conduire sa Raison et chercher la Vérité dans les Sciences." [70] "Eine thätige Skepsis ist die, welche unablässig bemüht ist sich selbst zu überwinden, und durch geregelte Erfahrung zu einer Art von bedingtrer Zuverlässigkeit zu gelangen."--_Maximen und Reflexionen_, 7 Abtheilung. [71] "Au milieu de toutes ses erreurs, il ne faut pas méconnaître une grande idée, qui consiste à avoir tenté pour la première fois de ramener tous les phénomènes naturels à n'être qu'un simple dévelloppement des lois de la mécanique," is the weighty judgment of Biot, cited by Bouillier (_Histoire de la Philosophie Cartésienne_, t. i. p. 196). [72] "Traité de l'Homme" (Cousin's Edition), p. 347. [73] Descartes pretends that he does not apply his views to the human body, but only to an imaginary machine which, if it could be constructed, would do all that the human body does; throwing a sop to Cerberus unworthily; and uselessly, because Cerberus was by no means stupid enough to swallow it. [74] "Traité de l'Homme," p. 427. [75] Compare "Traité des Passions," Art. XIII. and XVI. [76] Bouillier, into whose excellent "History of the Cartesian Philosophy" I had not looked when this passage was written, says, very justly, that Descartes "a merité le titre de pére de la physique, aussi bien que celui de pére de la métaphysique moderne" (t. i. p. 197). See also Kuno Fischer's "Geschichte der neuen Philosophie," Bd. i.; and the very remarkable work of Lange, "Geschichte des Materialismus."--A good translation of the latter would be a great service to philosophy in England. [77] For all the qualifications which need to be made here, I refer the reader to the thorough discussion of the nature of the relation between nerve-action and consciousness in Mr. Herbert Spencer's "Principles of Psychology," p. 115 _et seq._ [78] "And this is she who's put on cross so much, Even by them who ought to give her praise, Giving her wrongly ill repute and blame. But she is blessed, and she hears not this: She, with the other primal creatures, glad Revolves her sphere, and blessed joys herself." _Inferno_, vii. 90-95 (W.M. Rossetti's Translation). 
1043	----	THE STORY OF EVOLUTION By Joseph McCabe 1912 PREFACE An ingenious student of science once entertained his generation with a theory of how one might behold again all the stirring chapters that make up the story of the earth. The living scene of our time is lit by the light of the sun, and for every few rays that enter the human eye, and convey the image of it to the human mind, great floods of the reflected light pour out, swiftly and indefinitely, into space. Imagine, then, a man moving out into space more rapidly than light, his face turned toward the earth. Flashing through the void at, let us say, a million miles a second, he would (if we can overlook the dispersion of the rays of light) overtake in succession the light that fell on the French Revolution, the Reformation, the Norman Conquest, and the faces of the ancient empires. He would read, in reverse order, the living history of man and whatever lay before the coming of man. Few thought, as they smiled over this fairy tale of science, that some such panoramic survey of the story of the earth, and even of the heavens, might one day be made in a leisure hour by ordinary mortals; that in the soil on which they trod were surer records of the past than in its doubtful literary remains, and in the deeper rocks were records that dimly lit a vast abyss of time of which they never dreamed. It is the supreme achievement of modern science to have discovered and deciphered these records. The picture of the past which they afford is, on the whole, an outline sketch. Here and there the details, the colour, the light and shade, may be added; but the greater part of the canvas is left to the more skilful hand of a future generation, and even the broad lines are at times uncertain. Yet each age would know how far its scientific men have advanced in constructing that picture of the growth of the heavens and the earth, and the aim of the present volume is to give, in clear and plain language, as full an account of the story as the present condition of our knowledge and the limits of the volume will allow. The author has been for many years interested in the evolution of things, or the way in which suns and atoms, fishes and flowers, hills and elephants, even man and his institutions, came to be what they are. Lecturing and writing on one or other phase of the subject have, moreover, taught him a language which the inexpert seem to understand, although he is not content merely to give a superficial description of the past inhabitants of the earth. The particular features which, it is hoped, may give the book a distinctive place in the large literature of evolution are, first, that it includes the many evolutionary discoveries of the last few years, gathers its material from the score of sciences which confine themselves to separate aspects of the universe, and blends all these facts and discoveries in a more or less continuous chronicle of the life of the heavens and the earth. Then the author has endeavoured to show, not merely how, but why, scene succeeds scene in the chronicle of the earth, and life slowly climbs from level to level. He has taken nature in the past as we find it to-day: an interconnected whole, in which the changes of land and sea, of heat and cold, of swamp and hill, are faithfully reflected in the forms of its living population. And, finally, he has written for those who are not students of science, or whose knowledge may be confined to one branch of science, and used a plain speech which assumes no previous knowledge on the reader's part. For the rest, it will be found that no strained effort is made to trace pedigrees of animals and plants when the material is scanty; that, if on account of some especial interest disputable or conjectural speculations are admitted, they are frankly described as such; and that the more important differences of opinion which actually divide astronomers, geologists, biologists, and anthropologists are carefully taken into account and briefly explained. A few English and American works are recommended for the convenience of those who would study particular chapters more closely, but it has seemed useless, in such a work, to give a bibliography of the hundreds of English, American, French, German, and Italian works which have been consulted. CONTENTS I. THE DISCOVERY OF THE UNIVERSE II. THE FOUNDATIONS OF THE UNIVERSE III. THE BIRTH AND DEATH OF WORLDS IV. THE PREPARATION OF THE EARTH V. THE BEGINNING OF LIFE VI. THE INFANCY OF THE EARTH VII. THE PASSAGE TO THE LAND VIII. THE COAL-FOREST IX. THE ANIMALS OF THE COAL-FOREST X. THE PERMIAN REVOLUTION XI. THE MIDDLE AGES OF THE EARTH XII. THE AGE OF REPTILES XIII. THE BIRD AND THE MAMMAL XIV. IN THE DAYS OF THE CHALK XV. THE TERTIARY ERA XVI. THE FLOWER AND THE INSECT XVII. THE ORIGIN OF OUR MAMMALS XVIII. THE EVOLUTION OF MAN XIX. MAN AND THE GREAT ICE-AGE XX. THE DAWN OF CIVILISATION XXI. EVOLUTION IN HISTORY INDEX THE STORY OF EVOLUTION CHAPTER I. THE DISCOVERY OF THE UNIVERSE The beginning of the victorious career of modern science was very largely due to the making of two stimulating discoveries at the close of the Middle Ages. One was the discovery of the earth: the other the discovery of the universe. Men were confined, like molluscs in their shells, by a belief that they occupied the centre of a comparatively small disk--some ventured to say a globe--which was poised in a mysterious way in the middle of a small system of heavenly bodies. The general feeling was that these heavenly bodies were lamps hung on a not too remote ceiling for the purpose of lighting their ways. Then certain enterprising sailors--Vasco da Gama, Maghalaes, Columbus--brought home the news that the known world was only one side of an enormous globe, and that there were vast lands and great peoples thousands of miles across the ocean. The minds of men in Europe had hardly strained their shells sufficiently to embrace this larger earth when the second discovery was reported. The roof of the world, with its useful little system of heavenly bodies, began to crack and disclose a profound and mysterious universe surrounding them on every side. One cannot understand the solidity of the modern doctrine of the formation of the heavens and the earth until one appreciates this revolution. Before the law of gravitation had been discovered it was almost impossible to regard the universe as other than a small and compact system. We shall see that a few daring minds pierced the veil, and peered out wonderingly into the real universe beyond, but for the great mass of men it was quite impossible. To them the modern idea of a universe consisting of hundreds of millions of bodies, each weighing billions of tons, strewn over billions of miles of space, would have seemed the dream of a child or a savage. Material bodies were "heavy," and would "fall down" if they were not supported. The universe, they said, was a sensible scientific structure; things were supported in their respective places. A great dome, of some unknown but compact material, spanned the earth, and sustained the heavenly bodies. It might rest on the distant mountains, or be borne on the shoulders of an Atlas; or the whole cosmic scheme might be laid on the back of a gigantic elephant, and--if you pressed--the elephant might stand on the hard shell of a tortoise. But you were not encouraged to press. The idea of the vault had come from Babylon, the first home of science. No furnaces thickened that clear atmosphere, and the heavy-robed priests at the summit of each of the seven-staged temples were astronomers. Night by night for thousands of years they watched the stars and planets tracing their undeviating paths across the sky. To explain their movements the priest-astronomers invented the solid firmament. Beyond the known land, encircling it, was the sea, and beyond the sea was a range of high mountains, forming another girdle round the earth. On these mountains the dome of the heavens rested, much as the dome of St. Paul's rests on its lofty masonry. The sun travelled across its under-surface by day, and went back to the east during the night through a tunnel in the lower portion of the vault. To the common folk the priests explained that this framework of the world was the body of an ancient and disreputable goddess. The god of light had slit her in two, "as you do a dried fish," they said, and made the plain of the earth with one half and the blue arch of the heavens with the other. So Chaldaea lived out its 5000 years without discovering the universe. Egypt adopted the idea from more scientific Babylon. Amongst the fragments of its civilisation we find representations of the firmament as a goddess, arching over the earth on her hands and feet, condemned to that eternal posture by some victorious god. The idea spread amongst the smaller nations which were lit by the civilisation of Babylon and Egypt. Some blended it with coarse old legends; some, like the Persians and Hebrews, refined it. The Persians made fire a purer and lighter spirit, so that the stars would need no support. But everywhere the blue vault hemmed in the world and the ideas of men. It was so close, some said, that the birds could reach it. At last the genius of Greece brooded over the whole chaos of cosmical speculations. The native tradition of Greece was a little more helpful than the Babylonian teaching. First was chaos; then the heavier matter sank to the bottom, forming the disk of the earth, with the ocean poured round it, and the less coarse matter floated as an atmosphere above it, and the still finer matter formed an "aether" above the atmosphere. A remarkably good guess, in its very broad outline; but the solid firmament still arched the earth, and the stars were little undying fires in the vault. The earth itself was small and flat. It stretched (on the modern map) from about Gibraltar to the Caspian, and from Central Germany--where the entrance to the lower world was located--to the Atlas mountains. But all the varied and conflicting culture of the older empires was now passing into Greece, lighting up in succession the civilisations of Asia Minor, the Greek islands, and then Athens and its sister states. Men began to think. The first genius to have a glimpse of the truth seems to have been the grave and mystical Pythagorus (born about 582 B.C.). He taught his little school that the earth was a globe, not a disk, and that it turned on its axis in twenty-four hours. The earth and the other planets were revolving round the central fire of the system; but the sun was a reflection of this central fire, not the fire itself. Even Pythagoras, moreover, made the heavens a solid sphere revolving, with its stars, round the central fire; and the truth he discovered was mingled with so much mysticism, and confined to so small and retired a school, that it was quickly lost again. In the next generation Anaxagoras taught that the sun was a vast globe of white-hot iron, and that the stars were material bodies made white-hot by friction with the ether. A generation later the famous Democritus came nearer than any to the truth. The universe was composed of an infinite number of indestructible particles, called "atoms," which had gradually settled from a state of chaotic confusion to their present orderly arrangement in large masses. The sun was a body of enormous size, and the points of light in the Milky Way were similar suns at a tremendous distance from the earth. Our universe, moreover, was only one of an infinite number of universes, and an eternal cycle of destruction and re-formation was running through these myriads of worlds. By sheer speculation Greece was well on the way of discovery. Then the mists of philosophy fell between the mind of Greece and nature, and the notions of Democritus were rejected with disdain; and then, very speedily, the decay of the brilliant nation put an end to its feverish search for truth. Greek culture passed to Alexandria, where it met the remains of the culture of Egypt, Babylonia, and Persia, and one more remarkable effort was made to penetrate the outlying universe before the night of the Middle Ages fell on the old world. Astronomy was ardently studied at Alexandria, and was fortunately combined with an assiduous study of mathematics. Aristarchus (about 320-250 B.C.) calculated that the sun was 84,000,000 miles away; a vast expansion of the solar system and, for the time, a remarkable approach to the real figure (92,000,000) Eratosthenes (276-196 B.C.) made an extremely good calculation of the size of the earth, though he held it to be the centre of a small universe. He concluded that it was a globe measuring 27,000 (instead of 23,700) miles in circumference. Posidonius (135-51 B.C.) came even nearer with a calculation that the circumference was between 25,000 and 19,000 miles; and he made a fairly correct estimate of the diameter, and therefore distance, of the sun. Hipparchus (190-120 B.C.) made an extremely good calculation of the distance of the moon. By the brilliant work of the Alexandrian astronomers the old world seemed to be approaching the discovery of the universe. Men were beginning to think in millions, to gaze boldly into deep abysses of space, to talk of vast fiery globes that made the earth insignificant But the splendid energy gradually failed, and the long line was closed by Ptolemaeus, who once more put the earth in the centre of the system, and so imposed what is called the Ptolemaic system on Europe. The keen school-life of Alexandria still ran on, and there might have been a return to the saner early doctrines, but at last Alexandrian culture was extinguished in the blood of the aged Hypatia, and the night fell. Rome had had no genius for science; though Lucretius gave an immortal expression to the views of Democritus and Epicurus, and such writers as Cicero and Pliny did great service to a later age in preserving fragments of the older discoveries. The curtains were once more drawn about the earth. The glimpses which adventurous Greeks had obtained of the great outlying universe were forgotten for a thousand years. The earth became again the little platform in the centre of a little world, on which men and women played their little parts, preening themselves on their superiority to their pagan ancestors. I do not propose to tell the familiar story of the revival at any length. As far as the present subject is concerned, it was literally a Renascence, or re-birth, of Greek ideas. Constantinople having been taken by the Turks (1453), hundreds of Greek scholars, with their old literature, sought refuge in Europe, and the vigorous brain of the young nations brooded over the ancient speculations, just as the vigorous young brain of Greece had done two thousand years before. Copernicus (1473-1543) acknowledges that he found the secret of the movements of the heavenly bodies in the speculations of the old Greek thinkers. Galilei (1564-1642) enlarged the Copernican system with the aid of the telescope; and the telescope was an outcome of the new study of optics which had been inspired in Roger Bacon and other medieval scholars by the optical works, directly founded on the Greek, of the Spanish Moors. Giordano Bruno still further enlarged the system; he pictured the universe boldly as an infinite ocean of liquid ether, in which the stars, with retinues of inhabited planets, floated majestically. Bruno was burned at the stake (1600); but the curtains that had so long been drawn about the earth were now torn aside for ever, and men looked inquiringly into the unfathomable depths beyond. Descartes (1596-1650) revived the old Greek idea of a gradual evolution of the heavens and the earth from a primitive chaos of particles, taught that the stars stood out at unimaginable distances in the ocean of ether, and imagined the ether as stirring in gigantic whirlpools, which bore cosmic bodies in their orbits as the eddy in the river causes the cork to revolve. These stimulating conjectures made a deep impression on the new age. A series of great astronomers had meantime been patiently and scientifically laying the foundations of our knowledge. Kepler (1571-1630) formulated the laws of the movement of the planets; Newton (1642-1727) crowned the earlier work with his discovery of the real agency that sustains cosmic bodies in their relative positions. The primitive notion of a material frame and the confining dome of the ancients were abandoned. We know now that a framework of the most massive steel would be too frail to hold together even the moon and the earth. It would be rent by the strain. The action of gravitation is the all-sustaining power. Once introduce that idea, and the great ocean of ether might stretch illimitably on every side, and the vastest bodies might be scattered over it and traverse it in stupendous paths. Thus it came about that, as the little optic tube of Galilei slowly developed into the giant telescope of Herschel, and then into the powerful refracting telescopes of the United States of our time; as the new science of photography provided observers with a new eye--a sensitive plate that will register messages, which the human eye cannot detect, from far-off regions; and as a new instrument, the spectroscope, endowed astronomers with a power of perceiving fresh aspects of the inhabitants of space, the horizon rolled backward, and the mind contemplated a universe of colossal extent and power. Let us try to conceive this universe before we study its evolution. I do not adopt any of the numerous devices that have been invented for the purpose of impressing on the imagination the large figures we must use. One may doubt if any of them are effective, and they are at least familiar. Our solar system--the family of sun and planets which had been sheltered under a mighty dome resting on the hill-tops--has turned out to occupy a span of space some 16,000,000,000 miles in diameter. That is a very small area in the new universe. Draw a circle, 100 billion miles in diameter, round the sun, and you will find that it contains only three stars besides the sun. In other words, a sphere of space measuring 300 billion miles in circumference--we will not venture upon the number of cubic miles--contains only four stars (the sun, alpha Centauri, 21,185 Lalande, and 61 Cygni). However, this part of space seems to be below the average in point of population, and we must adopt a different way of estimating the magnitude of the universe from the number of its stellar citizens. Beyond the vast sphere of comparatively empty space immediately surrounding our sun lies the stellar universe into which our great telescopes are steadily penetrating. Recent astronomers give various calculations, ranging from 200,000,000 to 2,000,000,000, of the number of stars that have yet come within our faintest knowledge. Let us accept the modest provisional estimate of 500,000,000. Now, if we had reason to think that these stars were of much the same size and brilliance as our sun, we should be able roughly to calculate their distance from their faintness. We cannot do this, as they differ considerably in size and intrinsic brilliance. Sirius is more than twice the size of our sun and gives out twenty times as much light. Canopus emits 20,000 times as much light as the sun, but we cannot say, in this case, how much larger it is than the sun. Arcturus, however, belongs to the same class of stars as our sun, and astronomers conclude that it must be thousands of times larger than the sun. A few stars are known to be smaller than the sun. Some are, intrinsically, far more brilliant; some far less brilliant. Another method has been adopted, though this also must be regarded with great reserve. The distance of the nearer stars can be positively measured, and this has been done in a large number of cases. The proportion of such cases to the whole is still very small, but, as far as the results go, we find that stars of the first magnitude are, on the average, nearly 200 billion miles away; stars of the second magnitude nearly 300 billion; and stars of the third magnitude 450 billion. If this fifty per cent increase of distance for each lower magnitude of stars were certain and constant, the stars of the eighth magnitude would be 3000 billion miles away, and stars of the sixteenth magnitude would be 100,000 billion miles away; and there are still two fainter classes of stars which are registered on long-exposure photographs. The mere vastness of these figures is immaterial to the astronomer, but he warns us that the method is uncertain. We may be content to conclude that the starry universe over which our great telescopes keep watch stretches for thousands, and probably tens of thousands, of billions of miles. There are myriads of stars so remote that, though each is a vast incandescent globe at a temperature of many thousand degrees, and though their light is concentrated on the mirrors or in the lenses of our largest telescopes and directed upon the photographic plate at the rate of more than 800 billion waves a second, they take several hours to register the faintest point of light on the plate. When we reflect that the universe has grown with the growth of our telescopes and the application of photography we wonder whether we may as yet see only a fraction of the real universe, as small in comparison with the whole as the Babylonian system was in comparison with ours. We must be content to wonder. Some affirm that the universe is infinite; others that it is limited. We have no firm ground in science for either assertion. Those who claim that the system is limited point out that, as the stars decrease in brightness, they increase so enormously in number that the greater faintness is more than compensated, and therefore, if there were an infinite series of magnitudes, the midnight sky would be a blaze of light. But this theoretical reasoning does not allow for dense regions of space that may obstruct the light, or vast regions of vacancy between vast systems of stars. Even apart from the evidence that dark nebulae or other special light-absorbing regions do exist, the question is under discussion in science at the present moment whether light is not absorbed in the passage through ordinary space. There is reason to think that it is. Let us leave precarious speculations about finiteness and infinity to philosophers, and take the universe as we know it. Picture, then, on the more moderate estimate, these 500,000,000 suns scattered over tens of thousands of billions of miles. Whether they form one stupendous system, and what its structure may be, is too obscure a subject to be discussed here. Imagine yourself standing at a point from which you can survey the whole system and see into the depths and details of it. At one point is a single star (like our sun), billions of miles from its nearest neighbour, wearing out its solitary life in a portentous discharge of energy. Commonly the stars are in pairs, turning round a common centre in periods that may occupy hundreds of days or hundreds of years. Here and there they are gathered into clusters, sometimes to the number of thousands in a cluster, travelling together over the desert of space, or trailing in lines like luminous caravans. All are rushing headlong at inconceivable speeds. Few are known to be so sluggish as to run, like our sun, at only 8000 miles an hour. One of the "fixed" stars of the ancients, the mighty Arcturus, darts along at a rate of more than 250 miles a second. As they rush, their surfaces glowing at a temperature anywhere between 1000 and 20,000 degrees C., they shake the environing space with electric waves from every tiny particle of their body at a rate of from 400 billion to 800 billion waves a second. And somewhere round the fringe of one of the smaller suns there is a little globe, more than a million times smaller than the solitary star it attends, lost in the blaze of its light, on which human beings find a home during a short and late chapter of its history. Look at it again from another aspect. Every colour of the rainbow is found in the stars. Emerald, azure, ruby, gold, lilac, topaz, fawn--they shine with wonderful and mysterious beauty. But, whether these more delicate shades be really in the stars or no, three colours are certainly found in them. The stars sink from bluish white to yellow, and on to deep red. The immortal fires of the Greeks are dying. Piercing the depths with a dull red glow, here and there, are the dying suns; and if you look closely you will see, flitting like ghosts across the light of their luminous neighbours, the gaunt frames of dead worlds. Here and there are vast stretches of loose cosmic dust that seems to be gathering into embryonic stars; here and there are stars in infancy or in strenuous youth. You detect all the chief phases of the making of a world in the forms and fires of these colossal aggregations of matter. Like the chance crowd on which you may look down in the square of a great city, they range from the infant to the worn and sinking aged. There is this difference, however, that the embryos of worlds sprawl, gigantic and luminous, across the expanse; that the dark and mighty bodies of the dead rush, like the rest, at twenty or fifty miles a second; and that at intervals some appalling blaze, that dims even the fearful furnaces of the living, seems to announce the resurrection of the dead. And there is this further difference, that, strewn about the intermediate space between the gigantic spheres, is a mass of cosmic dust--minute grains, or large blocks, or shoals consisting of myriads of pieces, or immeasurable clouds of fine gas--that seems to be the rubbish left over after the making of worlds, or the material gathering for the making of other worlds. This is the universe that the nineteenth century discovered and the twentieth century is interpreting. Before we come to tell the fortunes of our little earth we have to see how matter is gathered into these stupendous globes of fire, how they come sometimes to have smaller bodies circling round them on which living things may appear, how they supply the heat and light and electricity that the living things need, and how the story of life on a planet is but a fragment of a larger story. We have to study the birth and death of worlds, perhaps the most impressive of all the studies that modern science offers us. Indeed, if we would read the whole story of evolution, there is an earlier chapter even than this; the latest chapter to be opened by science, the first to be read. We have to ask where the matter, which we are going to gather into worlds, itself came from; to understand more clearly what is the relation to it of the forces or energies--gravitation, electricity, etc.--with which we glibly mould it into worlds, or fashion it into living things; and, above all, to find out its relation to this mysterious ocean of ether in which it is found. Less than half a century ago the making of worlds was, in popular expositions of science, a comparatively easy business. Take an indefinite number of atoms of various gases and metals, scatter them in a fine cloud over some thousands of millions of miles of space, let gravitation slowly compress the cloud into a globe, its temperature rising through the compression, let it throw off a ring of matter, which in turn gravitation will compress into a globe, and you have your earth circulating round the sun. It is not quite so simple; in any case, serious men of science wanted to know how these convenient and assorted atoms happened to be there at all, and what was the real meaning of this equally convenient gravitation. There was a greater truth than he knew in the saying of an early physicist, that the atom had the look of a "manufactured article." It was increasingly felt, as the nineteenth century wore on, that the atoms had themselves been evolved out of some simpler material, and that ether might turn out to be the primordial chaos. There were even those who felt that ether would prove to be the one source of all matter and energy. And just before the century closed a light began to shine in those deeper abysses of the submaterial world, and the foundations of the universe began to appear. CHAPTER II. THE FOUNDATIONS OF THE UNIVERSE To the mind of the vast majority of earlier observers the phrase "foundations of the universe" would have suggested something enormously massive and solid. From what we have already seen we are prepared, on the contrary, to pass from the inconceivably large to the inconceivably small. Our sun is, as far as our present knowledge goes, one of modest dimensions. Arcturus and Canopus must be thousands of times larger than it. Yet our sun is 320,000 times heavier than the earth, and the earth weighs some 6,000,000,000,000,000,000,000 tons. But it is only in resolving these stupendous masses into their tiniest elements that we can reach the ultimate realities, or foundations, of the whole. Modern science rediscovered the atoms of Democritus, analysed the universe into innumerable swarms of these tiny particles, and then showed how the infinite variety of things could be built up by their combinations. For this it was necessary to suppose that the atoms were not all alike, but belonged to a large number of different classes. From twenty-six letters of the alphabet we could make millions of different words. From forty or fifty different "elements" the chemist could construct the most varied objects in nature, from the frame of a man to a landscape. But improved methods of research led to the discovery of new elements, and at last the chemist found that he had seventy or eighty of these "ultimate realities," each having its own very definite and very different characters. As it is the experience of science to find unity underlying variety, this was profoundly unsatisfactory, and the search began for the great unity which underlay the atoms of matter. The difficulty of the search may be illustrated by a few figures. Very delicate methods were invented for calculating the size of the atoms. Laymen are apt to smile--it is a very foolish smile--at these figures, but it is enough to say that the independent and even more delicate methods suggested by recent progress in physics have quite confirmed them. Take a cubic millimetre of hydrogen. As a millimetre is less than 1/25th of an inch, the reader must imagine a tiny bubble of gas that would fit comfortably inside the letter "o" as it is printed here. The various refined methods of the modern physicist show that there are 40,000 billion molecules (each consisting of two atoms of the gas) in this tiny bubble. It is a little universe, repeating on an infinitesimal scale the numbers and energies of the stellar universe. These molecules are not packed together, moreover, but are separated from each other by spaces which are enormous in proportion to the size of the atoms. Through these empty spaces the atoms dash at an average speed of more than a thousand miles an hour, each passing something like 6,000,000,000 of its neighbours in the course of every second. Yet this particle of gas is a thinly populated world in comparison with a particle of metal. Take a cubic centimetre of copper. In that very small square of solid matter (each side of the cube measuring a little more than a third of an inch) there are about a quadrillion atoms. It is these minute and elusive particles that modern physics sets out to master. At first it was noticed that the atom of hydrogen was the smallest or lightest of all, and the other atoms seemed to be multiples of it. A Russian chemist, Mendeleeff, drew up a table of the elements in illustration of this, grouping them in families, which seemed to point to hydrogen as the common parent, or ultimate constituent, of each. When newly discovered elements fell fairly into place in this scheme the idea was somewhat confidently advanced that the evolution of the elements was discovered. Thus an atom of carbon seemed to be a group of 12 atoms of hydrogen, an atom of oxygen 16, an atom of sulphur 32, an atom of copper 64, an atom of silver 108, an atom of gold 197, and so on. But more correct measurements showed that these figures were not quite exact, and the fraction of inexactness killed the theory. Long before the end of the nineteenth century students were looking wistfully to the ether for some explanation of the mystery. It was the veiled statue of Isis in the scientific world, and it resolutely kept its veil in spite of all progress. The "upper and limpid air" of the Greeks, the cosmic ocean of Giordano Bruno, was now an established reality. It was the vehicle that bore the terrific streams of energy from star to planet across the immense reaches of space. As the atoms of matter lay in it, one thought of the crystal forming in its mother-lye, or the star forming in the nebula, and wondered whether the atom was not in some such way condensed out of the ether. By the last decade of the century the theory was confidently advanced--notably by Lorentz and Larmor--though it was still without a positive basis. How the basis was found, in the last decade of the nineteenth century, may be told very briefly. Sir William Crookes had in 1874 applied himself to the task of creating something more nearly like a vacuum than the old air-pumps afforded. When he had found the means of reducing the quantity of gas in a tube until it was a million times thinner than the atmosphere, he made the experiment of sending an electric discharge through it, and found a very curious result. From the cathode (the negative electric point) certain rays proceeded which caused a green fluorescence on the glass of the tube. Since the discharge did not consist of the atoms of the gas, he concluded that it was a new and mysterious substance, which he called "radiant matter." But no progress was made in the interpretation of this strange material. The Crookes tube became one of the toys of science--and the lamp of other investigators. In 1895 Rontgen drew closer attention to the Crookes tube by discovering the rays which he called X-rays, but which now bear his name. They differ from ordinary light-waves in their length, their irregularity, and especially their power to pass through opaque bodies. A number of distinguished physicists now took up the study of the effect of sending an electric discharge through a vacuum, and the particles of "radiant matter" were soon identified. Sir J. J. Thomson, especially, was brilliantly successful in his interpretation. He proved that they were tiny corpuscles, more than a thousand times smaller than the atom of hydrogen, charged with negative electricity, and travelling at the rate of thousands of miles a second. They were the "electrons" in which modern physics sees the long-sought constituents of the atom. No sooner had interest been thoroughly aroused than it was announced that a fresh discovery had opened a new shaft into the underworld. Sir J. J. Thomson, pursuing his research, found in 1896 that compounds of uranium sent out rays that could penetrate black paper and affect the photographic plate; though in this case the French physicist, Becquerel, made the discovery simultaneously' and was the first to publish it. An army of investigators turned into the new field, and sought to penetrate the deep abyss that had almost suddenly disclosed itself. The quickening of astronomy by Galilei, or of zoology by Darwin, was slight in comparison with the stirring of our physical world by these increasing discoveries. And in 1898 M. and Mme. Curie made the further discovery which, in the popular mind, obliterated all the earlier achievements. They succeeded in isolating the new element, radium, which exhibits the actual process of an atom parting with its minute constituents. The story of radium is so recent that a few lines will suffice to recall as much as is needed for the purpose of this chapter. In their study of the emanations from uranium compounds the Curies were led to isolate the various elements of the compounds until they discovered that the discharge was predominantly due to one specific element, radium. Radium is itself probably a product of the disintegration of uranium, the heaviest of known metals, with an atomic weight some 240 times greater than that of hydrogen. But this massive atom of uranium has a life that is computed in thousands of millions of years. It is in radium and its offspring that we see most clearly the constitution of matter. A gramme (less than 15 1/2 grains) of radium contains--we will economise our space--4x10 (superscript)21 atoms. This tiny mass is, by its discharge, parting with its substance at the rate of one atom per second for every 10,000,000,000 atoms; in other words, the "indestructible" atom has, in this case, a term of life not exceeding 2500 years. In the discharge from the radium three elements have been distinguished. The first consists of atoms of the gas helium, which are hurled off at between 10,000 and 20,000 miles a second. The third element (in the order of classification) consists of waves analogous to the Rontgen rays. But the second element is a stream of electrons, which are expelled from the atom at the appalling speed of about 100,000 miles a second. Professor Le Bon has calculated that it would take 340,000 barrels of powder to discharge a bullet at that speed. But we shall see more presently of the enormous energy displayed within the little system of the atom. We may add that after its first transformation the radium passes, much more quickly, through a further series of changes. The frontiers of the atomic systems were breaking down. The next step was for students (notably Soddy and Rutherford) to find that radio-activity, or spontaneous discharge out of the atomic systems, was not confined to radium. Not only are other rare metals conspicuously active, but it is found that such familiar surfaces as damp cellars, rain, snow, etc., emit a lesser discharge. The value of the new material thus provided for the student of physics may be shown by one illustration. Sir J. J. Thomson observes that before these recent discoveries the investigator could not detect a gas unless about a billion molecules of it were present, and it must be remembered that the spectroscope had already gone far beyond ordinary chemical analysis in detecting the presence of substances in minute quantities. Since these discoveries we can recognise a single molecule, bearing an electric charge. With these extraordinary powers the physicist is able to penetrate a world that lies immeasurably below the range of the most powerful microscope, and introduce us to systems more bewildering than those of the astronomer. We pass from a portentous Brobdingnagia to a still more portentous Lilliputia. It has been ascertained that the mass of the electron is the 1/1700th part of that of an atom of hydrogen, of which, as we saw, billions of molecules have ample space to execute their terrific movements within the limits of the letter "o." It has been further shown that these electrons are identical, from whatever source they are obtained. The physicist therefore concludes--warning us that on this further point he is drawing a theoretical conclusion--that the atoms of ordinary matter are made up of electrons. If that is the case, the hydrogen atom, the lightest of all, must be a complex system of some 1700 electrons, and as we ascend the scale of atomic weight the clusters grow larger and larger, until we come to the atoms of the heavier metals with more than 250,000 electrons in each atom. But this is not the most surprising part of the discovery. Tiny as the dimensions of the atom are, they afford a vast space for the movement of these energetic little bodies. The speed of the stars in their courses is slow compared with the flight of the electrons. Since they fly out of the system, in the conditions we have described, at a speed of between 90,000 and 100,000 miles a second, they must be revolving with terrific rapidity within it. Indeed, the most extraordinary discovery of all is that of the energy imprisoned within these tiny systems, which men have for ages regarded as "dead" matter. Sir J. J. Thomson calculates that, allowing only one electron to each atom in a gramme of hydrogen, the tiny globule of gas will contain as much energy as would be obtained by burning thirty-five tons of coal. If, he says, an appreciable fraction of the energy that is contained in ordinary matter were to be set free, the earth would explode and return to its primitive nebulous condition. Mr. Fournier d'Albe tells us that the force with which electrons repel each other is a quadrillion times greater than the force of gravitation that brings atoms together; and that if two grammes of pure electrons could be placed one centimetre apart they would repel each other with a force equal to 320 quadrillion tons. The inexpert imagination reels, but it must be remembered that the speed of the electron is a measured quantity, and it is within the resources of science to estimate the force necessary to project it at that speed. [*] * See Sir J. J. Thomson, "The Corpuscular Theory of Matter" (1907) and--for a more elementary presentment--"Light Visible and Invisible" (1911); and Mr. Fournier d'Albe, "The Electron Theory" (2nd. ed., 1907). Such are the discoveries of the last fifteen years and a few of the mathematical deductions from them. We are not yet in a position to say positively that the atoms are composed of electrons, but it is clear that the experts are properly modest in claiming only that this is highly probable. The atom seems to be a little universe in which, in combination with positive electricity (the nature of which is still extremely obscure), from 1700 to 300,000 electrons revolve at a speed that reaches as high as 100,000 miles a second. Instead of being crowded together, however, in their minute system, each of them has, in proportion to its size, as ample a space to move in as a single speck of dust would have in a moderate-sized room (Thomson). This theory not only meets all the facts that have been discovered in an industrious decade of research, not only offers a splendid prospect of introducing unity into the eighty-one different elements of the chemist, but it opens out a still larger prospect of bringing a common measure into the diverse forces of the universe. Light is already generally recognised as a rapid series of electro-magnetic waves or pulses in ether. Magnetism becomes intelligible as a condition of a body in which the electrons revolve round the atom in nearly the same plane. The difference between positive and negative electricity is at least partly illuminated. An atom will repel an atom when its equilibrium is disturbed by the approach of an additional electron; the physicist even follows the movement of the added electron, and describes it revolving 2200 billion times a second round the atom, to escape being absorbed in it. The difference between good and bad conductors of electricity becomes intelligible. The atoms of metals are so close together that the roaming electrons pass freely from one atom to another, in copper, it is calculated, the electron combines with an atom and is liberated again a hundred million times a second. Even chemical action enters the sphere of explanation. However these hypotheses may fare, the electron is a fact, and the atom is very probably a more or less stable cluster of electrons. But when we go further, and attempt to trace the evolution of the electron out of ether, we enter a region of pure theory. Some of the experts conceive the electron as a minute whirlpool or vortex in the ocean of ether; some hold that it is a centre of strain in ether; some regard ether as a densely packed mass of infinitely small grains, and think that the positive and negative corpuscles, as they seem to us, are tiny areas in which the granules are unequally distributed. Each theory has its difficulties. We do not know the origin of the electron, because we do not know the nature of ether. To some it is an elastic solid, quivering in waves at every movement of the particles; to others it is a continuous fluid, every cubic millimetre of which possesses "an energy equivalent to the output of a million-horse-power station for 40.000,000 years" (Lodge); to others it is a close-packed granular mass with a pressure of 10,000 tons per square centimetre. We must wait. It is little over ten years since the vaults were opened and physicists began to peer into the sub-material world. The lower, perhaps lowest, depth is reserved for another generation. But it may be said that the research of the last ten years has given us a glimpse of the foundations of the universe. Every theory of the electron assumes it to be some sort of nodule or disturbed area in the ether. It is sometimes described as "a particle of negative electricity" and associated with "a particle of positive electricity" in building up the atom. The phrase is misleading for those who regard electricity as a force or energy, and it gives rise to speculation as to whether "matter" has not been resolved into "force." Force or energy is not conceived by physicists as a substantial reality, like matter, but an abstract expression of certain relations of matter or electrons. In any case, the ether, whether solid or fluid or granular, remains the fundamental reality. The universe does not float IN an ocean of ether: it IS an ocean of ether. But countless myriads of minute disturbances are found in this ocean, and set it quivering with the various pulses which we classify as forces or energies. These points of disturbance cluster together in systems (atoms) of from 1000 to 250,000 members, and the atoms are pressed together until they come in the end to form massive worlds. It remains only to reduce gravitation itself, which brings the atoms together, to a strain or stress in ether, and we have a superb unity. That has not yet been done, but every theory of gravitation assumes that it is a stress in the ether corresponding to the formation of the minute disturbances which we call electrons. But, it may be urged, he who speaks of foundations speaks of a beginning of a structure; he who speaks of evolution must have a starting-point. Was there a time when the ether was a smooth, continuous fluid, without electrons or atoms, and did they gradually appear in it, like crystals in the mother-lye? In science we know nothing of a beginning. The question of the eternity or non-eternity of matter (or ether) is as futile as the question about its infinity or finiteness. We shall see in the next chapter that science can trace the processes of nature back for hundreds, if not thousands, of millions of years, and has ground to think that the universe then presented much the same aspect as it does now, and will in thousands of millions of years to come. But if these periods were quadrillions, instead of millions, of years, they would still have no relation to the idea of eternity. All that we can say is that we find nothing in nature that points to a beginning or an end. [*] * A theory has been advanced by some physicists that there is evidence of a beginning. WITHIN OUR EXPERIENCE energy is being converted into heat more abundantly than heat is being converted into other energy. This would hold out a prospect of a paralysed universe, and that stage would have been reached long ago if the system had not had a definite beginning. But what knowledge have we of conversions of energy in remote regions of space, in the depths of stars or nebulae, or in the sub-material world of which we have just caught a glimpse? Roundly, none. The speculation is worthless. One point only need be mentioned in conclusion. Do we anywhere perceive the evolution of the material elements out of electrons, just as we perceive the devolution, or disintegration, of atoms into electrons? There is good ground for thinking that we do. The subject will be discussed more fully in the next chapter. In brief, the spectroscope, which examines the light of distant stars and discovers what chemical elements emitted it, finds matter, in the hottest stars, in an unusual condition, and seems to show the elements successively emerging from their fierce alchemy. Sir J. Norman Lockyer has for many years conducted a special investigation of the subject at the Solar Physics Observatory, and he declares that we can trace the evolution of the elements out of the fiery chaos of the young star. The lightest gases emerge first, the metals later, and in a special form. But here we pass once more from Lilliputia to Brobdingnagia, and must first explain the making of the star itself. CHAPTER III. THE BIRTH AND DEATH OF WORLDS The greater part of this volume will be occupied with the things that have happened on one small globe in the universe during a certain number of millions of years. It cannot be denied that this has a somewhat narrow and parochial aspect. The earth is, you remember, a million times smaller than the sun, and the sun itself is a very modest citizen of the stellar universe. Our procedure is justified, however, both on the ground of personal interest, and because our knowledge of the earth's story is so much more ample and confident. Yet we must preface the story of the earth with at least a general outline of the larger story of the universe. No sensible man is humbled or dismayed by the vastness of the universe. When the human mind reflects on its wonderful scientific mastery of this illimitable ocean of being, it has no sentiment of being dwarfed or degraded. It looks out with cold curiosity over the mighty scattering of worlds, and asks how they, including our own world, came into being. We now approach this subject with a clearer perception of the work we have to do. The universe is a vast expanse of ether, and somehow or other this ether gives rise to atoms of matter. We may imagine it as a spacious chamber filled with cosmic dust; recollecting that the chamber has no walls, and that the dust arises in the ether itself. The problem we now approach is, in a word: How are these enormous stretches of cosmic dust, which we call matter, swept together and compressed into suns and planets? The most famous answer to this question is the "nebular hypothesis." Let us see, briefly, how it came into modern science. We saw that some of the ancient Greek speculators imagined their infinite number of atoms as scattered originally, like dust, throughout space and gradually coming together, as dust does, to form worlds. The way in which they brought their atoms together was wrong, but the genius of Democritus had provided the germ of another sound theory to the students of a more enlightened age. Descartes (1596-1650) recalled the idea, and set out a theory of the evolution of stars and planets from a diffused chaos of particles. He even ventured to say that the earth was at one time a small white-hot sun, and that a solid crust had gradually formed round its molten core. Descartes had taken refuge in Sweden from his persecutors, and it is therefore not surprising that that strange genius Swedenborg shortly afterwards developed the same idea. In the middle of the eighteenth century the great French naturalist, Buffon, followed and improved upon Descartes and Swedenborg. From Buffon's work it was learned by the German philosopher Kant, who published (1755) a fresh theory of the concentration of scattered particles into fiery worlds. Then Laplace (1749-1827) took up the speculation, and gave it the form in which it practically ruled astronomy throughout the nineteenth century. That is the genealogy of the famous nebular hypothesis. It did not spring full-formed from the brain of either Kant or Laplace, like Athene from the brain of Zeus. Laplace had one great advantage over the early speculators. Not only was he an able astronomer and mathematician, but by his time it was known that nebulae, or vast clouds of dispersed matter, actually existed in the heavens. Here was a solid basis for the speculation. Sir William Herschel, the most assiduous explorer of the heavens, was a contemporary of Laplace. Laplace therefore took the nebula as his starting-point. A quarter of an ounce of solid matter (say, tobacco) will fill a vast space when it is turned into smoke, and if it were not for the pressure of the atmosphere it would expand still more. Laplace imagined the billions of tons of matter which constitute our solar system similarly dispersed, converted into a fine gas, immeasurably thinner than the atmosphere. This nebula would be gradually drawn in again by gravitation, just as the dust falls to the floor of a room. The collisions of its particles as they fell toward the centre would raise its temperature and give it a rotating movement. A time would come when the centrifugal force at the outer ring of the rotating disk would equal the centripetal (or inward) pull of gravity, and this ring would be detached, still spinning round the central body. The material of the ring would slowly gather, by gravitation, round some denser area in it; the ring would become a sphere; we should have the first, and outermost, planet circling round the sun. Other rings would successively be detached, and form the rest of the planets; and the sun is the shrunken and condensed body of the nebula. So simple and beautiful a theory of the solar system could not fail to captivate astronomers, but it is generally rejected to-day, in the precise form which Laplace gave it. What the difficulties are which it has encountered, and the modifications it must suffer, we shall see later; as well as the new theories which have largely displaced it. It will be better first to survey the universe from the evolutionary point of view. But I may observe, in passing, that the sceptical remarks one hears at times about scientific theories contradicting and superseding each other are frivolous. One great idea pervades all the theories of the evolution of worlds, and that idea is firmly established. The stars and their planets are enormous aggregations of cosmic dust, swept together and compressed by the action of gravitation. The precise nature of this cosmic dust--whether it was gas, meteorites and gas, or other particles--is open to question. As we saw in the first chapter, the universe has the word evolution written, literally, in letters of fire across it. The stars are of all ages, from sturdy youth to decrepit age, and even to the darkness of death. We saw that this can be detected on the superficial test of colour. The colours of the stars are, it is true, an unsafe ground to build upon. The astronomer still puzzles over the gorgeous colours he finds at times, especially in double stars: the topaz and azure companions in beta Cygni, the emerald and red of alpha Herculis, the yellow and rose of eta Cassiopeiae, and so on. It is at the present time under discussion in astronomy how far these colours are objective at all, or whether, if they are real, they may not be due to causes other than temperature. Yet the significance of the three predominating colours--blue-white, yellow, and red--has been sustained by the spectroscope. It is the series of colours through which a white-hot bar of iron passes as it cools. And the spectroscope gives us good ground to conclude that the stars are cooling. When a glowing gas (not under great pressure) is examined by the spectroscope, it yields a few vertical lines or bars of light on a dark background; when a glowing liquid or solid is examined, it gives a continuous rainbow-like stretch of colour. Some of the nebulae give the former type of spectrum, and are thus known to be masses of luminous gas; many of the nebulae and the stars have the latter type of spectrum. But the stretch of light in the spectrum of a star is crossed, vertically, by a number of dark lines, and experiment in the laboratory has taught us how to interpret these. They mean that there is some light-absorbing vapour between the source of light and the instrument. In the case of the stars they indicate the presence of an atmosphere of relatively cool vapours, and an increase in the density of that atmosphere--which is shown by a multiplication and broadening of the dark lines on the spectrum--means an increase of age, a loss of vitality, and ultimately death. So we get the descending scale of spectra. The dark lines are thinnest and least numerous in the blue stars, more numerous in the yellow, heavy and thick in the red. As the body of the star sinks in temperature dense masses of cool vapour gather about it. Its light, as we perceive it, turns yellow, then red. The next step, which the spectroscope cannot follow, will be the formation of a scum on the cooling surface, ending, after ages of struggle, in the imprisonment of the molten interior under a solid, dark crust. Let us see how our sun illustrates this theory. It is in the yellow, or what we may call the autumnal, stage. Miss Clerke and a few others have questioned this, but the evidence is too strong to-day. The vast globe, 867,000 miles in diameter, seems to be a mass of much the same material as the earth--about forty elements have been identified in it--but at a terrific temperature. The light-giving surface is found, on the most recent calculations, to have a temperature of about 6700 degrees C. This surface is an ocean of liquid or vaporised metals, several thousand miles in depth; some think that the brilliant light comes chiefly from clouds of incandescent carbon. Overlying it is a deep layer of the vapours of the molten metals, with a temperature of about 5500 degrees C.; and to this comparatively cool and light-absorbing layer we owe the black lines of the solar spectrum. Above it is an ocean of red-hot hydrogen, and outside this again is an atmosphere stretching for some hundreds of thousands of miles into space. The significant feature, from our point of view, is the "sun-spot"; though the spot may be an area of millions of square miles. These areas are, of course, dark only by comparison with the intense light of the rest of the disk. The darkest part of them is 5000 times brighter than the full moon. It will be seen further, on examining a photograph of the sun, that a network or veining of this dark material overspreads the entire surface at all times. There is still some difference of opinion as to the nature of these areas, but the evidence of the spectroscope has convinced most astronomers that they are masses of cooler vapour lying upon, and sinking into, the ocean of liquid fire. Round their edges, as if responding to the pressure of the more condensed mass, gigantic spurts and mountains of the white-hot matter of the sun rush upwards at a rate of fifty or a hundred miles a second, Sometimes they reach a height of a hundred, and even two hundred, thousand miles, driving the red-hot hydrogen before them in prodigious and fantastic flames. Between the black veins over the disk, also, there rise domes and columns of the liquid fire, some hundreds of miles in diameter, spreading and sinking at from five to twenty miles a second. The surface of the sun--how much more the interior!--is an appalling cauldron of incandescent matter from pole to pole. Every yard of the surface is a hundred times as intense as the open furnace of a Titanic. From the depths and from the surface of this fiery ocean, as, on a small scale, from the surface of the tropical sea, the vapours rise high into the extensive atmosphere, discharge some of their heat into space, and sink back, cooler and heavier, upon the disk. This is a star in its yellow age, as are Capella and Arcturus and other stars. The red stars carry the story further, as we should expect. The heavier lines in their spectrum indicate more absorption of light, and tell us that the vapours are thickening about the globe; while compounds like titanium oxide make their appearance, announcing a fall of temperature. Below these, again, is a group of dark red or "carbon" stars, in which the process is carried further. Thick, broad, dark lines in the red end of the spectrum announce the appearance of compounds of carbon, and a still lower fall of temperature. The veil is growing thicker; the life is ebbing from the great frame. Then the star sinks below the range of visibility, and one would think that we can follow the dying world no farther. Fortunately, in the case of Algol and some thirty or forty other stars, an extinct sun betrays its existence by flitting across the light of a luminous sun, and recent research has made it probable that the universe is strewn with dead worlds. Some of them may be still in the condition which we seem to find in Jupiter, hiding sullen fires under a dense shell of cloud; some may already be covered with a crust, like the earth. There are even stars in which one is tempted to see an intermediate stage: stars which blaze out periodically from dimness, as if the Cyclops were spending his last energy in spasms that burst the forming roof of his prison. But these variable stars are still obscure, and we do not need their aid. The downward course of a star is fairly plain. When we turn to the earlier chapters in the life of a star, the story is less clear. It is at least generally agreed that the blue-white stars exhibit an earlier and hotter stage. They show comparatively little absorption, and there is an immense preponderance of the lighter gases, hydrogen and helium. They (Sirius, Vega, etc.) are, in fact, known as "hydrogen stars," and their temperature is generally computed at between 20,000 and 30,000 degrees C. A few stars, such as Procyon and Canopus, seem to indicate a stage between them and the yellow or solar type. But we may avoid finer shades of opinion and disputed classes, and be content with these clear stages. We begin with stars in which only hydrogen and helium, the lightest Of elements, can be traced; and the hydrogen is in an unfamiliar form, implying terrific temperature. In the next stage we find the lines of oxygen, nitrogen, magnesium, and silicon. Metals such as iron and copper come later, at first in a primitive and unusual form. Lastly we get the compounds of titanium and carbon, and the densely shaded spectra which tell of the thickly gathering vapours. The intense cold of space is slowly prevailing in the great struggle. What came before the star? It is now beyond reasonable doubt that the nebula--taking the word, for the moment, in the general sense of a loose, chaotic mass of material--was the first stage. Professor Keeler calculated that there are at least 120,000 nebulae within range of our telescopes, and the number is likely to be increased. A German astronomer recently counted 1528 on one photographic plate. Many of them, moreover, are so vast that they must contain the material for making a great number of worlds. Examine a good photograph of the nebula in Orion. Recollect that each one of the points of light that are dotted over the expanse is a star of a million miles or more in diameter (taking our sun as below the average), and that the great cloud that sprawls across space is at least 10,000 billion miles away; how much more no man knows. It is futile to attempt to calculate the extent of that vast stretch of luminous gas. We can safely say that it is at least a million times as large as the whole area of our solar system; but it may run to trillions or quadrillions of miles. Nearly a hundred other nebulae are known, by the spectroscope, to be clouds of luminous gas. It does not follow that they are white-hot, and that the nebula is correctly called a "fire-mist." Electrical and other agencies may make gases luminous, and many astronomers think that the nebulae are intensely cold. However, the majority of the nebulae that have been examined are not gaseous, and have a very different structure from the loose and diffused clouds of gas. They show two (possibly more, but generally two) great spiral arms starting from the central part and winding out into space. As they are flat or disk-shaped, we see this structure plainly when they turn full face toward the earth, as does the magnificent nebula in Canes Venatici. In it, and many others, we clearly trace a condensed central mass, with two great arms, each apparently having smaller centres of condensation, sprawling outward like the broken spring of a watch. The same structure can be traced in the mighty nebula in Andromeda, which is visible to the naked eye, and it is said that more than half the nebulae in the heavens are spiral. Knowing that they are masses of solid or liquid fire, we are tempted to see in them gigantic Catherine-wheels, the fireworks of the gods. What is their relation to the stars? In the first place, their mere existence has provided a solid basis for the nebular hypothesis, and their spiral form irresistibly suggests that they are whirling round on their central axis and concentrating. Further, we find in some of the gaseous nebulae (Orion) comparatively void spaces occupied by stars, which seem to have absorbed the nebulous matter in their formation. On the other hand, we find (in the Pleiades) wisps and streamers of nebulous matter clinging about great clusters of stars, suggesting that they are material left over when these clustered worlds crystallised out of some vast nebula; and enormous stretches of nebulous material covering regions (as in Perseus) where the stars are as thick as grains of silver. More important still, we find a type of cosmic body which seems intermediate between the star and the nebula. It is a more or less imperfectly condensed star, surrounded by nebular masses. But one of the most instructive links of all is that at times a nebula is formed from a star, and a recent case of this character may be briefly described. In February, 1901, a new star appeared in the constellation Perseus. Knowing what a star is, the reader will have some dim conception of the portentous blaze that lit up that remote region of space (at least 600 billion miles away) when he learns that the light of this star increased 4000-fold in twenty-eight hours. It reached a brilliance 8000 times greater than that of the sun. Telescopes and spectroscopes were turned on it from all parts of the earth, and the spectroscope showed that masses of glowing hydrogen were rushing out from it at a rate of nearly a thousand miles a second. Its light gradually flickered and fell, however, and the star sank back into insignificance. But the photographic plate now revealed a new and most instructive feature. Before the end of the year there was a nebula, of enormous extent, spreading out on both sides from the centre of the eruption. It was suggested at the time that the bursting of a star may merely have lit up a previously dark nebula, but the spectroscope does not support this. A dim star had dissolved, wholly or partially, into a nebula, as a result of some mighty cataclysm. What the nature of the catastrophe was we will inquire presently. These are a few of the actual connections that we find between stars and nebulae. Probably, however, the consideration that weighs most with the astronomer is that the condensation of such a loose, far-stretched expanse of matter affords an admirable explanation of the enormous heat of the stars. Until recently there was no other conceivable source that would supply the sun's tremendous outpour of energy for tens of millions of years except the compression of its substance. It is true that the discovery of radio-activity has disclosed a new source of energy within the atoms themselves, and there are scientific men, like Professor Arrhenius, who attach great importance to this source. But, although it may prolong the limited term of life which physicists formerly allotted to the sun and other stars, it is still felt that the condensation of a nebula offers the best explanation of the origin of a sun, and we have ample evidence for the connection. We must, therefore, see what the nebula is, and how it develops. "Nebula" is merely the Latin word for cloud. Whatever the nature of these diffused stretches of matter may be, then, the name applies fitly to them, and any theory of the development of a star from them is still a "nebular hypothesis." But the three theories which divide astronomers to-day differ as to the nature of the nebula. The older theory, pointing to the gaseous nebulae as the first stage, holds that the nebula is a cloud of extremely attenuated gas. The meteoritic hypothesis (Sir N. Lockyer, Sir G. Darwin, etc.), observing that space seems to swarm with meteors and that the greater part of the nebulae are not gaseous, believes that the starting-point is a colossal swarm of meteors, surrounded by the gases evolved and lit up by their collisions. The planetesimal hypothesis, advanced in recent years by Professor Moulton and Professor Chamberlin, contends that the nebula is a vast cloud of liquid or solid (but not gaseous) particles. This theory is based mainly on the dynamical difficulties of the other two, which we will notice presently. The truth often lies between conflicting theories, or they may apply to different cases. It is not improbable that this will be our experience in regard to the nature of the initial nebula. The gaseous nebulae, and the formation of such nebulae from disrupted stars, are facts that cannot be ignored. The nebulae with a continuous spectrum, and therefore--in part, at least--in a liquid or solid condition, may very well be regarded as a more advanced stage of condensation of the same; their spiral shape and conspicuous nuclei are consistent with this. Moreover, a condensing swarm of meteors would, owing to the heat evolved, tend to pass into a gaseous condition. On the tether hand, a huge expanse of gas stretched over billions of miles of space would be a net for the wandering particles, meteors, and comets that roam through space. If it be true, as is calculated, that our 24,000 miles of atmosphere capture a hundred million meteors a day, what would the millions or billions of times larger net of a nebula catch, even if the gas is so much thinner? In other words, it is not wise to draw too fine a line between a gaseous nebula and one consisting of solid particles with gas. The more important question is: How do astronomers conceive the condensation of this mixed mass of cosmic dust? It is easy to reply that gravitation, or the pressure of the surrounding ether, slowly drives the particles centre-ward, and compresses the dust into globes, as the boy squeezes the flocculent snow into balls; and it is not difficult for the mathematician to show that this condensation would account for the shape and temperature of the stars. But we must go a little beyond this superficial statement, and see, to some extent, how the deeper students work out the process. [*] * See, especially, Dr. P. Lowell, "The Evolution of Worlds" (1909). Professor S. Arrhenius, "Worlds in the Making" (1908), Sir N. Lockyer, "The Meteorite Hypothesis" (1890), Sir R. Ball, "The Earth's Beginning" (1909), Professor Moulton, "The Astrophysical Journal (October, 1905), and Chamberlin and Salisbury, "Geology," Vol. II. (1903). Taking a broad view of the whole field, one may say that the two chief difficulties are as follows: First, how to get the whole chaotic mass whirling round in one common direction; secondly, how to account for the fact that in our solar system the outermost planets and satellites do not rotate in the same direction as the rest. There is a widespread idea that these difficulties have proved fatal to the old nebular hypothesis, and there are distinguished astronomers who think so. But Sir R. Ball (see note), Professor Lowell (see note), Professor Pickering (Annals of Harvard College Observatory, 53, III), and other high authorities deny this, and work out the newly discovered movements on the lines of the old theory. They hold that all the bodies in the solar system once turned in the same direction as Uranus and Neptune, and the tidal influence of the sun has changed the rotation of most of them. The planets farthest from the sun would naturally not be so much affected by it. The same principle would explain the retrograde movement of the outer satellites of Saturn and Jupiter. Sir R. Ball further works out the principles on which the particles of the condensing nebula would tend to form a disk rotating on its central axis. The ring-theory of Laplace is practically abandoned. The spiral nebula is evidently the standard type, and the condensing nebula must conform to it. In this we are greatly helped by the current theory of the origin of spiral nebulae. We saw previously that new stars sometimes appear in the sky, and the recent closer scrutiny of the heavens shows this occurrence to be fairly frequent. It is still held by a few astronomers that such a cataclysm means that two stars collided. Even a partial or "grazing" collision between two masses, each weighing billions of tons, travelling (on the average) forty or fifty miles a second--a movement that would increase enormously as they approach each other--would certainly liquefy or vaporise their substance; but the astronomer, accustomed to see cosmic bodies escape each other by increasing their speed, is generally disinclined to believe in collisions. Some have made the new star plunge into the heart of a dense and dark nebula; some have imagined a shock of two gigantic swarms of meteors; some have regarded the outflame as the effect of a prodigious explosion. In one or other new star each or any of these things may have occurred, but the most plausible and accepted theory for the new star of 1901 and some others is that two stars had approached each other too closely in their wandering. Suppose that, in millions of years to come, when our sun is extinct and a firm crust surrounds the great molten ball, some other sun approaches within a few million miles of it. The two would rush past each other at a terrific speed, but the gravitational effect of the approaching star would tear open the solid shell of the sun, and, in a mighty flame, its molten and gaseous entrails would be flung out into space. It has long been one of the arguments against a molten interior of the earth that the sun's gravitational influence would raise it in gigantic tides and rend the solid shell of rock. It is even suspected now that our small earth is not without a tidal influence on the sun. The comparatively near approach of two suns would lead to a terrific cataclysm. If we accept this theory, the origin of the spiral nebula becomes intelligible. As the sun from which it is formed is already rotating on its axis, we get a rotation of the nebula from the first. The mass poured out from the body of the sun would, even if it were only a small fraction of its mass, suffice to make a planetary system; all our sun's planets and their satellites taken together amount to only 1/100th of the mass of the solar system. We may assume, further, that the outpoured matter would be a mixed cloud of gases and solid and liquid particles; and that it would stream out, possibly in successive waves, from more than one part of the disrupted sun, tending to form great spiral trails round the parent mass. Some astronomers even suggest that, as there are tidal waves raised by the moon at opposite points of the earth, similar tidal outbursts would occur at opposite points on the disk of the disrupted star, and thus give rise to the characteristic arms starting from opposite sides of the spiral nebula. This is not at all clear, as the two tidal waves of the earth are due to the fact that it has a liquid ocean rolling on, not under, a solid bed. In any case, we have here a good suggestion of the origin of the spiral nebula and of its further development. As soon as the outbursts are over, and the scattered particles have reached the farthest limit to which they are hurled, the concentrating action of gravitation will slowly assert itself. If we conceive this gravitational influence as the pressure of the surrounding ether we get a wider understanding of the process. Much of the dispersed matter may have been shot far enough into space to escape the gravitational pull of the parent mass, and will be added to the sum of scattered cosmic dust, meteors, and close shoals of meteors (comets) wandering in space. Much of the rest will fall back upon the central body But in the great spiral arms themselves the distribution of the matter will be irregular, and the denser areas will slowly gather in the surrounding material. In the end we would thus get secondary spheres circling round a large primary. This is the way in which astronomers now generally conceive the destruction and re-formation of worlds. On one point the new planetesimal theory differs from the other theories. It supposes that, since the particles of the whirling nebula are all travelling in the same general direction, they overtake each other with less violent impact than the other theories suppose, and therefore the condensation of the material into planets would not give rise to the terrific heat which is generally assumed. We will consider this in the next chapter, when we deal with the formation of the planets. As far as the central body, the sun, is concerned, there can be no hesitation. The 500,000,000 incandescent suns in the heavens are eloquent proof of the appalling heat that is engendered by the collisions of the concentrating particles. In general outline we now follow the story of a star with some confidence. An internal explosion, a fatal rush into some dense nebula or swarm of meteors, a collision with another star, or an approach within a few million miles of another star, scatters, in part or whole, the solid or liquid globe in a cloud of cosmic dust. When the violent outrush is over, the dust is gathered together once more into a star. At first cold and attenuated, its temperature rises as the particles come together, and we have, after a time, an incandescent nucleus shining through a thin veil of gas--a nebulous star. The temperature rises still further, and we have the blue-hot star, in which the elements seem to be dissociated, and slowly re-forming as the temperature falls. After, perhaps, hundreds of millions of years it reaches the "yellow" stage, and, if it has planets with the conditions of life, there may be a temporary opportunity for living things to enjoy its tempered energy. But the cooler vapours are gathering round it, and at length its luminous body is wholly imprisoned. It continues its terrific course through space, until some day, perhaps, it again encounters the mighty cataclysm which will make it begin afresh the long and stormy chapters of its living history. Such is the suggestion of the modern astronomer, and, although we seem to find every phase of the theory embodied in the varied contents of the heavens, we must not forget that it is only a suggestion. The spectroscope and telescopic photography, which are far more important than the visual telescope, are comparatively recent, and the field to be explored is enormous. The mist is lifting from the cosmic landscape, but there is still enough to blur our vision. Very puzzling questions remain unanswered. What is the origin of the great gaseous nebulae? What is the origin of the triple or quadruple star? What is the meaning of stars whose light ebbs and flows in periods of from a few to several hundred days? We may even point to the fact that some, at least, of the spiral nebulae are far too vast to be the outcome of the impact or approach of two stars. We may be content to think that we have found out some truths, by no means the whole truth, about the evolution of worlds. Throughout this immeasurable ocean of ether the particles of matter are driven together and form bodies. These bodies swarm throughout space, like fish in the sea; travelling singly (the "shooting star"), or in great close shoals (the nucleus of a comet), or lying scattered in vast clouds. But the inexorable pressure urges them still, until billions of tons of material are gathered together. Then, either from the sheer heat of the compression, or from the formation of large and unstable atomic systems (radium, etc.), or both, the great mass becomes a cauldron of fire, mantled in its own vapours, and the story of a star is run. It dies out in one part of space to begin afresh in another. We see nothing in the nature of a beginning or an end for the totality of worlds, the universe. The life of all living things on the earth, from the formation of the primitive microbes to the last struggles of the superman, is a small episode of that stupendous drama, a fraction of a single scene. But our ampler knowledge of it, and our personal interest in it, magnify that episode, and we turn from the cosmic picture to study the formation of the earth and the rise of its living population. CHAPTER IV. THE PREPARATION OF THE EARTH The story of the evolution of our solar system is, it will now be seen, a local instance of the great cosmic process we have studied in the last chapter. We may take one of the small spiral nebulae that abound in the heavens as an illustration of the first stage. If a still earlier stage is demanded, we may suppose that some previous sun collided with, or approached too closely, another mighty body, and belched out a large part of its contents in mighty volcanic outpours. Mathematical reasoning can show that this erupted material would gather into a spiral nebula; but, as mathematical calculations cannot be given here, and are less safe than astronomical facts, we will be content to see the early shape of our solar system in a relatively small spiral nebula, its outermost arm stretching far beyond the present orbit of Neptune, and its great nucleus being our present sun in more diffused form. We need not now attempt to follow the shrinking of the central part of the nebula until it becomes a rounded fiery sun. That has been done in tracing the evolution of a star. Here we have to learn how the planets were formed from the spiral arms of the nebula. The principle of their formation is already clear. The same force of gravitation, or the same pressure of the surrounding ether, which compresses the central mass into a fiery globe, will act upon the loose material of the arms and compress it into smaller globes. But there is an interesting and acute difference of opinion amongst modern experts as to whether these smaller globes, the early planets, would become white-hot bodies. The general opinion, especially among astronomers, is that the compression of the nebulous material of the arms into globes would generate enormous heat, as in the case of the sun. On that view the various planets would begin their careers as small suns, and would pass through those stages of cooling and shrinking which we have traced in the story of the stars. A glance at the photograph of one of the spiral nebulae strongly confirms this. Great luminous knots, or nuclei, are seen at intervals in the arms. Smaller suns seem to be forming in them, each gathering into its body the neighbouring material of the arm, and rising in temperature as the mass is compressed into a globe. The spectroscope shows that these knots are condensing masses of white-hot liquid or solid matter. It therefore seems plain that each planet will first become a liquid globe of fire, coursing round the central sun, and will gradually, as its heat is dissipated and the supply begins to fail, form a solid crust. This familiar view is challenged by the new "planetesimal hypothesis," which has been adopted by many distinguished geologists (Chamberlin, Gregory, Coleman, etc.). In their view the particles in the arms of the nebula are all moving in the same direction round the sun. They therefore quietly overtake the nucleus to which they are attracted, instead of violently colliding with each other, and much less heat is generated at the surface. In that case the planets would not pass through a white-hot, or even red-hot, stage at all. They are formed by a slow ingathering of the scattered particles, which are called "planetesimals" round the larger or denser masses of stuff which were discharged by the exploding sun. Possibly these masses were prevented from falling back into the sun by the attraction of the colliding body, or the body which caused the eruption. They would revolve round the parent body, and the shoals of smaller particles would gather about them by gravitation. If there were any large region in the arm of the nebula which had no single massive nucleus, the cosmic dust would gather about a number of smaller centres. Thus might be explained the hundreds of planetoids, or minor planets, which we find between Mars and Jupiter. If these smaller bodies came within the sphere of influence of one of the larger planets, yet were travelling quickly enough to resist its attraction, they would be compelled to revolve round it, and we could thus explain the ten satellites of Saturn and the eight of Jupiter. Our moon, we shall see, had a different origin. We shall find this new hypothesis crossing the familiar lines at many points in the next few chapters. We will consider those further consequences as they arise, but may say at once that, while the new theory has greatly helped us in tracing the formation of the planetary system, astronomers are strongly opposed to its claim that the planets did not pass through an incandescent stage. The actual features of our spiral nebulae seem clearly to exhibit that stage. The shape of the planets--globular bodies, flattened at the poles--strongly suggests that they were once liquid. The condition in which we find Saturn and Jupiter very forcibly confirms this suggestion; the latest study of those planets supports the current opinion that they are still red-hot, and even seems to detect the glow of their surfaces in their mantles of cloud. These points will be considered more fully presently. For the moment it is enough to note that, as far as the early stages of planetary development are concerned, the generally accepted theory rests on a mass of positive evidence, while the new hypothesis is purely theoretical. We therefore follow the prevailing view with some confidence. Those of the spiral nebulae which face the earth squarely afford an excellent suggestion of the way in which planets are probably formed. In some of these nebulae the arms consist of almost continuous streams of faintly luminous matter; in others the matter is gathering about distinct centres; in others again the nebulous matter is, for the most part, collected in large glowing spheres. They seem to be successive stages, and to reveal to us the origin of our planets. The position of each planet in our solar system would be determined by the chance position of the denser stuff shot out by the erupting sun. I have seen Vesuvius hurl up into the sky, amongst its blasts of gas and steam, white-hot masses of rock weighing fifty tons. In the far fiercer outburst of the erupting sun there would be at least thinner and denser masses, and they must have been hurled so far into space that their speed in travelling round the central body, perhaps seconded by the attraction of the second star, overcame the gravitational pull back to the centre. Recollect the force which, in the new star in Perseus, drove masses of hydrogen for millions of miles at a speed of a thousand miles a second. These denser nuclei or masses would, when the eruption was over, begin to attract to themselves all the lighter nebulous material within their sphere of gravitational influence. Naturally, there would at first be a vast confusion of small and large centres of condensation in the arms of the nebula, moving in various directions, but a kind of natural selection--and, in this case, survival of the biggest--would ensue. The conflicting movements would be adjusted by collisions and gravitation, the smaller bodies would be absorbed in the larger or enslaved as their satellites, and the last state would be a family of smaller suns circling at vast distances round the parent body. The planets, moreover, would be caused to rotate on their axes, besides revolving round the sun, as the particles at their inner edge (nearer the sun) would move at a different speed from those at the outer edge. In the course of time the smaller bodies, having less heat to lose and less (or no) atmosphere to check the loss, would cool down, and become dark solid spheres, lit only by the central fire. While the first stage of this theory of development is seen in the spiral nebula, the later stages seem to be well exemplified in the actual condition of our planets. Following, chiefly, the latest research of Professor Lowell and his colleagues, which marks a considerable advance on our previous knowledge, we shall find it useful to glance at the sister-planets before we approach the particular story of our earth. Mercury, the innermost and smallest of the planets, measuring only some 3400 miles in diameter, is, not unexpectedly, an airless wilderness. Small bodies are unable to retain the gases at their surface, on account of their feebler gravitation. We find, moreover, that Mercury always presents the same face to the sun, as it turns on its axis in the same period (eighty-eight days) in which it makes a revolution round the sun. While, therefore, one half of the globe is buried in eternal darkness, the other half is eternally exposed to the direct and blistering rays of the sun, which is only 86,000,000 miles away. To Professor Lowell it presents the appearance of a bleached and sun-cracked desert, or "the bones of a dead world." Its temperature must be at least 300 degrees C. above that of the earth. Its features are what we should expect on the nebular hypothesis. The slowness of its rotation is accounted for by the heavy tidal influence of the sun. In the same way our moon has been influenced by the earth, and our earth by the sun, in their movement of rotation. Venus, as might be expected in the case of so large a globe (nearly as large as the earth), has an atmosphere, but it seems, like Mercury, always to present the same face to the sun. Its comparative nearness to the sun (67,000,000 miles) probably explains this advanced effect of tidal action. The consequences that the observers deduce from the fact are interesting. The sun-baked half of Venus seems to be devoid of water or vapour, and it is thought that all its water is gathered into a rigid ice-field on the dark side of the globe, from which fierce hurricanes must blow incessantly. It is a Sahara, or a desert far hotter than the Sahara, on one side; an arctic region on the other. It does not seem to be a world fitted for the support of any kind of life that we can imagine. When we turn to the consideration of Mars, we enter a world of unending controversy. With little more than half the diameter of the earth, Mars ought to be in a far more advanced stage of either life or decay, but its condition has not yet been established. Some hold that it has a considerable atmosphere; others that it is too small a globe to have retained a layer of gas. Professor Poynting believes that its temperature is below the freezing-point of water all over the globe; many others, if not the majority of observers, hold that the white cap we see at its poles is a mass of ice and snow, or at least a thick coat of hoar-frost, and that it melts at the edges as the springtime of Mars comes round. In regard to its famous canals we are no nearer agreement. Some maintain that the markings are not really an objective feature; some hold that they are due to volcanic activity, and that similar markings are found on the moon; some believe that they are due to clouds; while Professor Lowell and others stoutly adhere to the familiar view that they are artificial canals, or the strips of vegetation along such canals. The question of the actual habitation of Mars is still open. We can say only that there is strong evidence of its possession of the conditions of life in some degree, and that living things, even on the earth, display a remarkable power of adaptation to widely differing conditions. Passing over the 700 planetoids, which circulate between Mars and Jupiter, and for which we may account either by the absence of one large nucleus in that part of the nebulous stream or by the disturbing influence of Jupiter, we come to the largest planet of the system. Here we find a surprising confirmation of the theory of planetary development which we are following. Three hundred times heavier than the earth (or more than a trillion tons in weight), yet a thousand times less in volume than the sun, Jupiter ought, if our theory is correct, to be still red-hot. All the evidence conspires to suggest that it is. It has long been recognised that the shining disk of the planet is not a solid, but a cloud, surface. This impenetrable mass of cloud or vapour is drawn out in streams or belts from side to side, as the giant globe turns on its axis once in every ten hours. We cannot say if, or to what extent, these clouds consist of water-vapour. We can conclude only that this mantle of Jupiter is "a seething cauldron of vapours" (Lowell), and that, if the body beneath is solid, it must be very hot. A large red area, at one time 30,000 miles long, has more or less persisted on the surface for several decades, and it is generally interpreted, either as a red-hot surface, or as a vast volcanic vent, reflecting its glow upon the clouds. Indeed, the keen American observers, with their powerful telescopes, have detected a cherry-red glow on the edges of the cloud-belts across the disk; and more recent observation with the spectroscope seems to prove that Jupiter emits light from its surface analogous to that of the red stars. The conspicuous flattening of its poles is another feature that science would expect in a rapidly rotating liquid globe. In a word, Jupiter seems to be in the last stage of stellar development. Such, at some remote time, was our earth; such one day will be the sun. The neighbouring planet Saturn supports the conclusion. Here again we have a gigantic globe, 28,000 miles in diameter, turning on its axis in the short space of ten hours; and here again we find the conspicuous flattening of the poles, the trailing belts of massed vapour across the disk, the red glow lighting the edges of the belts, and the spectroscopic evidence of an emission of light. Once more it is difficult to doubt that a highly heated body is wrapped in that thick mantle of vapour. With its ten moons and its marvellous ring-system--an enormous collection of fragments, which the influence of the planet or of its nearer satellites seems to have prevented from concentrating--Saturn has always been a beautiful object to observe; it is not less interesting in those features which we faintly detect in its disk. The next planet, Uranus, 32,000 miles in diameter, seems to be another cloud-wrapt, greatly heated globe, if not, as some think, a sheer mass of vapours without a liquid core. Neptune is too dim and distant for profitable examination. It may be added, however, that the dense masses of gas which are found to surround the outer planets seem to confirm the nebular theory, which assumes that they were developed in the outer and lighter part of the material hurled from the sun. From this encouraging survey of the sister-planets we return with more confidence to the story of the earth. I will not attempt to follow an imaginative scheme in regard to its early development. Take four photographs--one of a spiral nebula without knots in its arms, one of a nebula like that in Canes Venatici, one of the sun, and one of Jupiter--and you have an excellent illustration of the chief stages in its formation. In the first picture a section of the luminous arm of the nebula stretches thinly across millions of miles of space. In the next stage this material is largely collected in a luminous and hazy sphere, as we find in the nebula in Canes Venatici. The sun serves to illustrate a further stage in the condensation of this sphere. Jupiter represents a later chapter, in which the cooler vapours are wrapped close about the red-hot body of the planet. That seems to have been the early story of the earth. Some 6,000,000,000 billion tons of the nebulous matter were attracted to a common centre. As the particles pressed centreward, the temperature rose, and for a time the generation of heat was greater than its dissipation. Whether the earth ever shone as a small white star we cannot say. We must not hastily conclude that such a relatively small mass would behave like the far greater mass of a star, but we may, without attempting to determine its temperature, assume that it runs an analogous course. One of the many features which I have indicated as pointing to a former fluidity of the earth may be explained here. We shall see in the course of this work that the mountain chains and other great irregularities of the earth's surface appear at a late stage in its development. Even as we find them to-day, they are seen to be merely slight ridges and furrows on the face of the globe, when we reflect on its enormous diameter, but there is good reason to think that in the beginning the earth was much nearer to a perfectly globular form. This points to a liquid or gaseous condition at one time, and the flattening of the sphere at the poles confirms the impression. We should hardly expect so perfect a rotundity in a body formed by the cool accretion of solid fragments and particles. It is just what we should expect in a fluid body, and the later irregularities of the surface are accounted for by the constant crumpling and wearing of its solid crust. Many would find a confirmation of this in the phenomena of volcanoes, geysers, and earthquakes, and the increase of the temperature as we descend the crust. But the interior condition of the earth, and the nature of these phenomena, are much disputed at present, and it is better not to rely on any theory of them. It is suggested that radium may be responsible for this subterraneous heat. The next stage in the formation of the earth is necessarily one that we can reach only by conjecture. Over the globe of molten fire the vapours and gases would be suspended like a heavy canopy, as we find in Jupiter and Saturn to-day. When the period of maximum heat production was passed, however, the radiation into space would cause a lowering of the temperature, and a scum would form on the molten surface. As may be observed on the surface of any cooling vessel of fluid, the scum would stretch and crack; the skin would, so to say, prove too small for the body. The molten ocean below would surge through the crust, and bury it under floods of lava. Some hold that the slabs would sink in the ocean of metal, and thus the earth would first solidify in its deeper layers. There would, in any case, be an age-long struggle between the molten mass and the confining crust, until at length--to employ the old Roman conception of the activity of Etna--the giant was imprisoned below the heavy roof of rock. Here again we seem to find evidence of the general correctness of the theory. The objection has been raised that the geologist does not find any rocks which he can identify as portions of the primitive crust of the earth. It seems to me that it would be too much to expect the survival at the surface of any part of the first scum that cooled on that fiery ocean. It is more natural to suppose that millions of years of volcanic activity on a prodigious scale would characterise this early stage, and the "primitive crust" would be buried in fragments, or dissolved again, under deep seas of lava. Now, this is precisely what we find, The oldest rocks known to the geologist--the Archaean rocks--are overwhelmingly volcanic, especially in their lower part. Their thickness, as we know them, is estimated at 50,000 feet; a thickness which must represent many millions of years. But we do not know how much thicker than this they may be. They underlie the oldest rocks that have ever been exposed to the gaze of the geologist. They include sedimentary deposits, showing the action of water, and even probable traces of organic remains, but they are, especially in their deeper and older sections, predominantly volcanic. They evince what we may call a volcanic age in the early story of the planet. But before we pursue this part of the story further we must interpolate a remarkable event in the record--the birth of the moon. It is now generally believed, on a theory elaborated by Sir G. Darwin, that when the formation of the crust had reached a certain depth--something over thirty miles, it is calculated--it parted with a mass of matter, which became the moon. The size of our moon, in comparison with the earth, is so exceptional among the satellites which attend the planets of our solar system that it is assigned an exceptional origin. It is calculated that at that time the earth turned on its axis in the space of four or five hours, instead of twenty-four. We have already seen that the tidal influence of the sun has the effect of moderating the rotation of the planets. Now, this very rapid rotation of a liquid mass, with a thin crust, would (together with the instability occasioned by its cooling) cause it to bulge at the equator. The bulge would increase until the earth became a pear-shaped body. The small end of the pear would draw further and further away from the rest--as a drop of water does on the mouth of a tap--and at last the whole mass (some 5,000,000,000 cubic miles of matter) was broken off, and began to pursue an independent orbit round the earth. There are astronomers who think that other cosmic bodies, besides our moon, may have been formed in this way. Possibly it is true of some of the double stars, but we will not return to that question. The further story of the moon, as it is known to astronomers, may be given in a few words. The rotational movement of the earth is becoming gradually slower on account of tidal influence; our day, in fact, becomes an hour longer every few million years. It can be shown that this had the effect of increasing the speed, and therefore enlarging the orbit, of the moon, as it revolved round the earth. As a result, the moon drew further and further away from the earth until it reached its present position, about 240,000 miles away. At the same time the tidal influence of the earth was lessening the rotational movement of the moon. This went on until it turned on its axis in the same period in which it revolves round the earth, and on this account it always presents the same face to the earth. Through what chapters of life the moon may have passed in the meantime it is impossible to say. Its relatively small mass may have been unable to keep the lighter gases at its surface, or its air and water may, as some think, have been absorbed. It is to-day practically an airless and waterless desert, alternating between the heat of its long day and the intense cold of its long night. Careful observers, such as Professor Pickering, think that it may still have a shallow layer of heavy gases at its surface, and that this may permit the growth of some stunted vegetation during the day. Certain changes of colour, which are observed on its surface, have been interpreted in that sense. We can hardly conceive any other kind of life on it. In the dark even the gases will freeze on its surface, as there is no atmosphere to retain the heat. Indeed, some students of the moon (Fauth, etc.) believe that it is an unchanging desert of ice, bombarded by the projectiles of space. An ingenious speculation as to the effect on the earth of this dislodgment of 5,000,000,000 cubic miles of its substance is worth noting. It supposes that the bed of the Pacific Ocean represents the enormous gap torn in its side by the delivery of the moon. At each side of this chasm the two continents, the Old World and the New, would be left floating on their molten ocean; and some have even seen a confirmation of this in the lines of crustal weakness which we trace, by volcanoes and earthquakes, on either side of the Pacific. Others, again, connect the shape of our great masses of land, which generally run to a southern point, with this early catastrophe. But these interesting speculations have a very slender basis, and we will return to the story of the development of the earth. The last phase in preparation for the appearance of life would be the formation of the ocean. On the lines of the generally received nebular hypothesis this can easily be imagined, in broad outline. The gases would form the outer shell of the forming planet, since the heavier particles would travel inward. In this mixed mass of gas the oxygen and hydrogen would combine, at a fitting temperature, and form water. For ages the molten crust would hold this water suspended aloft as a surrounding shell of cloud, but when the surface cooled to about 380 degrees C. (Sollas), the liquid would begin to pour on it. A period of conflict would ensue, the still heated crust and the frequent volcanic outpours sending the water back in hissing steam to the clouds. At length, and now more rapidly, the temperature of the crust would sink still lower, and a heated ocean would settle upon it, filling the hollows of its irregular surface, and washing the bases of its outstanding ridges. From that time begins the age-long battle of the land and the water which, we shall see, has had a profound influence on the development of life. In deference to the opinion of a number of geologists we must glance once more at the alternative view of the planetesimal school. In their opinion the molecules of water were partly attracted to the surface out of the disrupted matter, and partly collected within the porous outer layers of the globe. As the latter quantity grew, it would ooze upwards, fill the smaller depressions in the crust, and at length, with the addition of the attracted water, spread over the irregular surface. There is an even more important difference of opinion in regard to the formation of the atmosphere, but we may defer this until the question of climate interests us. We have now made our globe, and will pass on to that early chapter of its story in which living things make their appearance. To some it will seem that we ought not to pass from the question of origin without a word on the subject of the age of the earth. All that one can do, however, is to give a number of very divergent estimates. Physicists have tried to calculate the age of the sun from the rate of its dissipation of heat, and have assigned, at the most, a hundred million years to our solar system; but the recent discovery of a source of heat in the disintegration of such metals as radium has made their calculations useless. Geologists have endeavoured, from observation of the action of geological agencies to-day, to estimate how long it will have taken them to form the stratified crust of the earth; but even the best estimates vary between twenty-five and a hundred million years, and we have reason to think that the intensity of these geological agencies may have varied in different ages. Chemists have calculated how long it would take the ocean, which was originally fresh water, to take up from the rocks and rivers the salt which it contains to-day; Professor Joly has on this ground assigned a hundred million years since the waters first descended upon the crust. We must be content to know that the best recent estimates, based on positive data, vary between fifty and a hundred million years for the story which we are now about to narrate. The earlier or astronomical period remains quite incalculable. Sir G. Darwin thinks that it was probably at least a thousand million years since the moon was separated from the earth. Whatever the period of time may be since some cosmic cataclysm scattered the material of our solar system in the form of a nebula, it is only a fraction of that larger and illimitable time which the evolution of the stars dimly suggests to the scientific imagination. THE GEOLOGICAL SERIES [The scale of years adopted--50,000,000 for the stratified rocks--is merely an intermediate between conflicting estimates.] ERA. PERIOD. RELATIVE LENGTH. Quaternary Holocene 500,000 years Pleistocene Tertiary Pliocene 5,500,000 years or Miocene Cenozoic Oligocene Eocene Secondary Cretaceous 7,200,000 years or Jurassic 3,600,000 " Mesozoic Triassic 2,500,000 " Primary Permian 2,800,000 years or Carboniferous 6,200,000 " Palaeozoic Devonian 8,000,000 " Silurian 5,400,000 " Ordovician 5,400,000 " Cambrian 8,000,000 " Archaean Keweenawan Unknown (probably Animikie at least Huronian 50,000,000 years) Keewatin Laurentian CHAPTER V. THE BEGINNING OF LIFE There is, perhaps, no other chapter in the chronicle of the earth that we approach with so lively an interest as the chapter which should record the first appearance of life. Unfortunately, as far as the authentic memorials of the past go, no other chapter is so impenetrably obscure as this. The reason is simple. It is a familiar saying that life has written its own record, the long-drawn record of its dynasties and its deaths, in the rocks. But there were millions of years during which life had not yet learned to write its record, and further millions of years the record of which has been irremediably destroyed. The first volume of the geological chronicle of the earth is the mass of the Archaean (or "primitive") rocks. What the actual magnitude of that volume, and the span of time it covers, may be, no geologist can say. The Archaean rocks still solidly underlie the lowest depth he has ever reached. It is computed, however, that these rocks, as far as they are known to us, have a total depth of nearly ten miles, and seem therefore to represent at least half the story of the earth from the time when it rounded into a globe, or cooled sufficiently to endure the presence of oceans. Yet all that we read of the earth's story during those many millions of years could be told in a page or two. That section of geology is still in its infancy, it is true. A day may come when science will decipher a long and instructive narrative in the masses of quartz and gneiss, and the layers of various kinds, which it calls the Archaean rocks. But we may say with confidence that it will not discover in them more than a few stray syllables of the earlier part, and none whatever of the earliest part, of the epic of living nature. A few fossilised remains of somewhat advanced organisms, such as shell-fish and worms, are found in the higher and later rocks of the series, and more of the same comparatively high types will probably appear. In the earlier strata, representing an earlier stage of life, we find only thick seams of black shale, limestone, and ironstone, in which we seem to see the ashes of primitive organisms, cremated in the appalling fires of the volcanic age, or crushed out of recognition by the superimposed masses. Even if some wizardry of science were ever to restore the forms that have been reduced to ashes in this Archaean crematorium, it would be found that they are more or less advanced forms, far above the original level of life. No trace will ever be found in the rocks of the first few million years in the calendar of life. The word impossible or unknowable is not lightly uttered in science to-day, but there is a very plain reason for admitting it here. The earliest living things were at least as primitive of nature as the lowest animals and plants we know to-day, and these, up to a fair level of organisation, are so soft of texture that, when they die, they leave no remains which may one day be turned into fossils. Some of them, indeed, form tiny shells of flint or lime, or, like the corals, make for themselves a solid bed; but this is a relatively late and higher stage of development. Many thousands of species of animals and plants lie below that level. We are therefore forced to conclude, from the aspect of living nature to-day, that for ages the early organisms had no hard and preservable parts. In thus declaring the impotence of geology, however, we are at the same time introducing another science, biology, which can throw appreciable light on the evolution of life. Let us first see what geology tells us about the infancy of the earth. The distribution of the early rocks suggests that there was comparatively little dry land showing above the surface of the Archaean ocean. Our knowledge of these rocks is not at all complete, and we must remember that some of this primitive land may be now under the sea or buried in unsuspected regions. It is significant, however, that, up to the present, exploration seems to show that in those remote ages only about one-fifth of our actual land-surface stood above the level of the waters. Apart from a patch of some 20,000 square miles of what is now Australia, and smaller patches in Tasmania, New Zealand, and India, nearly the whole of this land was in the far North. A considerable area of eastern Canada had emerged, with lesser islands standing out to the west and south of North America. Another large area lay round the basin of the Baltic; and as Greenland, the Hebrides, and the extreme tip of Scotland, belong to the same age, it is believed that a continent, of which they are fragments, united America and Europe across the North Atlantic. Of the rest of what is now Europe there were merely large islands--one on the border of England and Wales, others in France, Spain, and Southern Germany. Asia was represented by a large area in China and Siberia, and an island or islands on the site of India. Very little of Africa or South America existed. It will be seen at a glance that the physical story of the earth from that time is a record of the emergence from the waters of larger continents and the formation of lofty chains of mountains. Now this world-old battle of land and sea has been waged with varying fortune from age to age, and it has been one of the most important factors in the development of life. We are just beginning to realise what a wonderful light it throws on the upward advance of animals and plants. No one in the scientific world to-day questions that, however imperfect the record may be, there has been a continuous development of life from the lowest level to the highest. But why there was advance at all, why the primitive microbe climbs the scale of being, during millions of years, until it reaches the stature of humanity, seems to many a profound mystery. The solution of this mystery begins to break upon us when we contemplate, in the geological record, the prolonged series of changes in the face of the earth itself, and try to realise how these changes must have impelled living things to fresh and higher adaptations to their changing surroundings. Imagine some early continent with its population of animals and plants. Each bay, estuary, river, and lake, each forest and marsh and solid plain, has its distinctive inhabitants. Imagine this continent slowly sinking into the sea, until the advancing arms of the salt water meet across it, mingling their diverse populations in a common world, making the fresh-water lake brackish or salt, turning the dry land into swamp, and flooding the forest. Or suppose, on the other hand, that the land rises, the marsh is drained, the genial climate succeeded by an icy cold, the luscious vegetation destroyed, the whole animal population compelled to change its habits and its food. But this is no imaginary picture. It is the actual story of the earth during millions of years, and it is chiefly in the light of these vast and exacting changes in the environment that we are going to survey the panorama of the advance of terrestrial life. For the moment it will be enough to state two leading principles. The first is that there is no such thing as a "law of evolution" in the sense in which many people understand that phrase. It is now sufficiently well known that, when science speaks of a law, it does not mean that there is some rule that things MUST act in such and such a way. The law is a mere general expression of the fact that they DO act in that way. But many imagine that there is some principle within the living organism which impels it onward to a higher level of organisation. That is entirely an error. There is no "law of progress." If an animal is fitted to secure its livelihood and breed posterity in certain surroundings, it may remain unchanged indefinitely if these surroundings do not materially change. So the duckmole of Australia and the tuatara of New Zealand have retained primitive features for millions of years; so the aboriginal Australian and the Fuegian have remained stagnant, in their isolation, for a hundred thousand years or more; so the Chinaman, in his geographical isolation, has remained unchanged for two thousand years. There is no more a "conservative instinct" in Chinese than there is a "progressive instinct" in Europeans. The difference is one of history and geography, as we shall see. To make this important principle still clearer, let us imagine some primitive philosopher observing the advance of the tide over a level beach. He must discover two things: why the water comes onward at all, and why it advances along those particular channels. We shall see later how men of science explain or interpret the mechanism in a living thing which enables it to advance, when it does advance. For the present it is enough to say that new-born animals and plants are always tending to differ somewhat from their parents, and we now know, by experiment, that when some exceptional influence is brought to bear on the parent, the young may differ considerably from her. But, if the parents were already in harmony with their environment, these variations on the part of the young are of no consequence. Let the environment alter, however, and some of these variations may chance to make the young better fitted than the parent was. The young which happen to have the useful variation will have an advantage over their brothers or sisters, and be more likely to survive and breed the next generation. If the change in the environment (in the food or climate, for instance) is prolonged and increased for hundreds of thousands of years, we shall expect to find a corresponding change in the animals and plants. We shall find such changes occurring throughout the story of the earth. At one important point in the story we shall find so grave a revolution in the face of nature that twenty-nine out of every thirty species of animals and plants on the earth are annihilated. Less destructive and extreme changes have been taking place during nearly the whole of the period we have to cover, entailing a more gradual alteration of the structure of animals and plants; but we shall repeatedly find them culminating in very great changes of climate, or of the distribution of land and water, which have subjected the living population of the earth to the most searching tests and promoted every variation toward a more effective organisation. [*] * This is a very simple expression of "Darwinism," and will be enlarged later. The reader should ignore the occasional statement of non-scientific writers that Darwinism is "dead" or superseded. The questions which are actually in dispute relate to the causes of the variation of the young from their parents, the magnitude of these variations' and the transmission of changes acquired by an animal during its own life. We shall see this more fully at a later stage. The importance of the environment as I have described it, is admitted by all schools. And the second guiding principle I wish to lay down in advance is that these great changes in the face of the earth, which explain the progress of organisms, may very largely be reduced to one simple agency--the battle of the land and the sea. When you gaze at some line of cliffs that is being eaten away by the waves, or reflect on the material carried out to sea by the flooded river, you are--paradoxical as it may seem--beholding a material process that has had a profound influence on the development of life. The Archaean continent that we described was being reduced constantly by the wash of rain, the scouring of rivers, and the fretting of the waves on the coast. It is generally thought that these wearing agencies were more violent in early times, but that is disputed, and we will not build on it. In any case, in the course of time millions of tons of matter were scraped off the Archaean continent and laid on the floor of the sea by its rivers. This meant a very serious alteration of pressure or weight on the surface of the globe, and was bound to entail a reaction or restoration of the balance. The rise of the land and formation of mountains used to be ascribed mainly to the cooling and shrinking of the globe of the earth. The skin (crust), it was thought, would become too large for the globe as it shrank, and would wrinkle outwards, or pucker up into mountain-chains. The position of our greater mountain-chains sprawling across half the earth (the Pyrenees to the Himalaya, and the Rocky Mountains to the Andes), seems to confirm this, but the question of the interior of the earth is obscure and disputed, and geologists generally conceive the rise of land and formation of mountains in a different way. They are due probably to the alteration of pressure on the crust in combination with the instability of the interior. The floors of the seas would sink still lower under their colossal burdens, and this would cause some draining of the land-surface. At the same time the heavy pressure below the seas and the lessening of pressure over the land would provoke a reaction. Enormous masses of rock would be forced toward and underneath the land-surface, bending, crumpling, and upheaving it as if its crust were but a leather coat. As a result, masses of land would slowly rise above the plain, to be shaped into hills and valleys by the hand of later time, and fresh surfaces would be dragged out of the deep, enlarging the fringes of the primitive continents, to be warped and crumpled in their turn at the next era of pressure. In point of geological fact, the story of the earth has been one prolonged series of changes in the level of land and water, and in their respective limits. These changes have usually been very gradual, but they have always entailed changes (in climate, etc. ) of the greatest significance in the evolution of life. What was the swampy soil of England in the Carboniferous period is now sometimes thousands of feet beneath us; and what was the floor of a deep ocean over much of Europe and Asia at another time is now to be found on the slopes of lofty Alps, or 20,000 feet above the sea-level in Thibet. Our story of terrestrial life will be, to a great extent, the story of how animals and plants changed their structure in the long series of changes which this endless battle of land and sea brought over the face of the earth. As we have no recognisable remains of the animals and plants of the earliest age, we will not linger over the Archaean rocks. Starting from deep and obscure masses of volcanic matter, the geologist, as he travels up the series of Archaean rocks, can trace only a dim and most unsatisfactory picture of those remote times. Between outpours of volcanic floods he finds, after a time, traces that an ocean and rivers are wearing away the land. He finds seams of carbon among the rocks of the second division of the Archaean (the Keewatin), and deduces from this that a dense sea-weed population already covered the floor of the ocean. In the next division (the Huronian) he finds the traces of extensive ice-action strangely lying between masses of volcanic rock, and sees that thousands of square miles of eastern North America were then covered with an ice-sheet. Then fresh floods of molten matter are poured out from the depths below; then the sea floods the land for a time; and at last it makes its final emergence as the first definitive part of the North American continent, to enlarge, by successive fringes, to the continent of to-day. [*] * I am quoting Professor Coleman's summary of Archaean research in North America (Address to the Geological Section of the British Association, 1909). Europe, as a continent, has had more "ups and downs" than America in the course of geological time. This meagre picture of the battle of land and sea, with interludes of great volcanic activity and even of an ice age, represents nearly all we know of the first half of the world's story from geology. It is especially disappointing in regard to the living population. The very few fossils we find in the upper Archaean rocks are so similar to those we shall discuss in the next chapter that we may disregard them, and the seams of carbon-shales, iron-ore, and limestone, suggest only, at the most, that life was already abundant. We must turn elsewhere for some information on the origin and early development of life. The question of the origin of life I will dismiss with a brief account of the various speculations of recent students of science. Broadly speaking, their views fall into three classes. Some think that the germs of life may have come to the earth from some other body in the universe; some think that life was evolved out of non-living matter in the early ages of the earth, under exceptional conditions which we do not at present know, or can only dimly conjecture; and some think that life is being evolved from non-life in nature to-day, and always has been so evolving. The majority of scientific men merely assume that the earliest living things were no exception to the general process of evolution, but think that we have too little positive knowledge to speculate profitably on the manner of their origin. The first view, that the germs of life may have come to this planet on a meteoric visitor from some other world, as a storm-driven bird may take its parasites to some distant island, is not without adherents to-day. It was put forward long ago by Lord Kelvin and others; it has been revived by the distinguished Swede, Professor Svante Arrhenius. The scientific objection to it is that the more intense (ultra-violet) rays of the sun would frill such germs as they pass through space. But a broader objection, and one that may dispense us from dwelling on it, is that we gain nothing by throwing our problems upon another planet. We have no ground for supposing that the earth is less capable of evolving life than other planets. The second view is that, when the earth had passed through its white-hot stage, great masses of very complex chemicals, produced by the great heat, were found on its surface. There is one complex chemical substance in particular, called cyanogen, which is either an important constituent of living matter, or closely akin to it. Now we need intense heat to produce this substance in the laboratory. May we not suppose that masses of it were produced during the incandescence of the earth, and that, when the waters descended, they passed through a series of changes which culminated in living plasm? Such is the "cyanogen hypothesis" of the origin of life, advocated by able physiologists such as Pfluger, Verworn, and others. It has the merit of suggesting a reason why life may not be evolving from non-life in nature to-day, although it may have so evolved in the Archaean period. Other students suggest other combinations of carbon-compounds and water in the early days. Some suggest that electric action was probably far more intense in those ages; others think that quantities of radium may have been left at the surface. But the most important of these speculations on the origin of life in early times, and one that has the merit of not assuming any essentially different conditions then than we find now, is contained in a recent pronouncement of one of the greatest organic chemists in Europe, Professor Armstrong. He says that such great progress has been made in his science--the science of the chemical processes in living things--that "their cryptic character seems to have disappeared almost suddenly." On the strength of this new knowledge of living matter, he ventures to say that "a series of lucky accidents" could account for the first formation of living things out of non-living matter in Archaean times. Indeed, he goes further. He names certain inorganic substances, and says that the blowing of these into pools by the wind on the primitive planet would set afoot chemical combinations which would issue in the production of living matter. [*] * See his address in Nature, vol. 76, p. 651. For other speculations see Verworn's "General Physiology," Butler Burke's "Origin of Life" (1906), and Dr. Bastian's "Origin of Life" (1911). It is evident that the popular notion that scientific men have declared that life cannot be evolved from non-life is very far astray. This blunder is usually due to a misunderstanding of the dogmatic statement which one often reads in scientific works that "every living thing comes from a living thing." This principle has no reference to remote ages, when the conditions may have been different. It means that to-day, within our experience, the living thing is always born of a living parent. However, even this is questioned by some scientific men of eminence, and we come to the third view. Professor Nageli, a distinguished botanist, and Professor Haeckel, maintain that our experience, as well as the range of our microscopes, is too limited to justify the current axiom. They believe that life may be evolving constantly from inorganic matter. Professor J. A. Thomson also warns us that our experience is very limited, and, for all we know, protoplasm may be forming naturally in our own time. Mr. Butler Burke has, under the action of radium, caused the birth of certain minute specks which strangely imitate the behaviour of bacteria. Dr. Bastian has maintained for years that he has produced living things from non-living matter. In his latest experiments, described in the book quoted, purely inorganic matter is used, and it is previously subjected, in hermetically sealed tubes, to a heat greater than what has been found necessary to kill any germs whatever. Evidently the problem of the origin of life is not hopeless, but our knowledge of the nature of living matter is still so imperfect that we may leave detailed speculation on its origin to a future generation. Organic chemistry is making such strides that the day may not be far distant when living matter will be made by the chemist, and the secret of its origin revealed. For the present we must be content to choose the more plausible of the best-informed speculations on the subject. But while the origin of life is obscure, the early stages of its evolution come fairly within the range of our knowledge. To the inexpert it must seem strange that, whereas we must rely on pure speculation in attempting to trace the origin of life, we can speak with more confidence of those early developments of plants and animals which are equally buried in the mists of the Archaean period. Have we not said that nothing remains of the procession of organisms during half the earth's story but a shapeless seam of carbon or limestone? A simple illustration will serve to justify the procedure we are about to adopt. Suppose that the whole of our literary and pictorial references to earlier stages in the development of the bicycle, the locomotive, or the loom, were destroyed. We should still be able to retrace the phases of their evolution, because we should discover specimens belonging to those early phases lingering in our museums, in backward regions, and elsewhere. They might yet be useful in certain environments into which the higher machines have not penetrated. In the same way, if all the remains of prehistoric man and early civilisation were lost, we could still fairly retrace the steps of the human race, by gathering the lower tribes and races, and arranging them in the order of their advancement. They are so many surviving illustrations of the stages through which mankind as a whole has passed. Just in the same way we may marshal the countless species of animals and plants to-day in such order that they will, in a general way, exhibit to us the age-long procession of life. From the very start of living evolution certain forms dropped out of the onward march, and have remained, to our great instruction, what their ancestors were millions of years ago. People create a difficulty for themselves by imagining that, if evolution is true, all animals must evolve. A glance at our own fellows will show the error of this. Of one family of human beings, as a French writer has said, one only becomes a Napoleon; the others remain Lucien, Jerome, or Joseph. Of one family of animals or trees, some advance in one or other direction; some remain at the original level. There is no "law of progress." The accidents of the world and hereditary endowment impel some onward, and do not impel others. Hence at nearly every great stage in the upward procession through the ages some regiment of plants or animals has dropped out, and it represents to-day the stage of life at which it ceased to progress. In other words, when we survey the line of the hundreds of thousands of species which we find in nature to-day, we can trace, amid their countless variations and branches, the line of organic evolution in the past; just as we could, from actual instances, study the evolution of a British house, from the prehistoric remains in Devonshire to a mansion in Park Lane or a provincial castle. Another method of retracing the lost early chapters in the development of life is furnished by embryology. The value of this method is not recognised by all embryologists, but there are now few authorities who question the substantial correctness of it, and we shall, as we proceed, see some remarkable applications of it. In brief, it is generally admitted that an animal or plant is apt to reproduce, during its embryonic development, some of the stages of its ancestry in past time. This does not mean that a higher animal, whose ancestors were at one time worms, at another time fishes, and at a later time reptiles, will successively take the form of a little worm, a little fish, and a little reptile. The embryonic life itself has been subject to evolution, and this reproduction of ancestral forms has been proportionately disturbed. Still, we shall find that animals will tend, in their embryonic development, to reproduce various structural features which can only be understood as reminiscences of ancestral organs. In the lower animals the reproduction is much less disturbed than in the higher, but even in the case of man this law is most strikingly verified. We shall find it useful sometimes at least in confirming our conclusions as to the ancestry of a particular group. We have, therefore, two important clues to the missing chapters in the story of evolution. Just as the scheme of the evolution of worlds is written broadly across the face of the heavens to-day, so the scheme of the evolution of life is written on the face of living nature; and it is written again, in blurred and broken characters, in the embryonic development of each individual. With these aids we set out to restore the lost beginning of the epic of organic evolution. CHAPTER VI. THE INFANCY OF THE EARTH The long Archaean period, into which half the story of the earth is so unsatisfactorily packed, came to a close with a considerable uplift of the land. We have seen that the earth at times reaches critical stages owing to the transfer of millions of tons of matter from the land to the depths of the ocean, and the need to readjust the pressure on the crust. Apparently this stage is reached at the end of the Archaean, and a great rise of the land--probably protracted during hundreds of thousands of years--takes place. The shore-bottoms round the primitive continent are raised above the water, their rocks crumpling like plates of lead under the overpowering pressure. The sea retires with its inhabitants, mingling their various provinces, transforming their settled homes. A larger continent spans the northern ocean of the earth. In the shore-waters of this early continent are myriads of living things, representing all the great families of the animal world below the level of the fish and the insect. The mud and sand in which their frames are entombed, as they die, will one day be the "Cambrian" rocks of the geologist, and reveal to him their forms and suggest their habits. No great volcanic age will reduce them to streaks of shapeless carbon. The earth now buries its dead, and from their petrified remains we conjure up a picture of the swarming life of the Cambrian ocean. A strange, sluggish population burrows in the mud, crawls over the sand, adheres to the rocks, and swims among the thickets of sea-weed. The strangest and most formidable, though still too puny a thing to survive in a more strenuous age, is the familiar Trilobite of the geological museum; a flattish animal with broad, round head, like a shovel, its back covered with a three-lobed shell, and a number of fine legs or swimmers below. It burrows in the loose bottom, or lies in it with its large compound eyes peeping out in search of prey. It is the chief representative of the hard-cased group (Crustacea) which will later replace it with the lobster, the shrimp, the crab, and the water-flea. Its remains form from a third to a fourth of all the buried Cambrian skeletons. With it, swimming in the water, are smaller members of the same family, which come nearer to our familiar small Crustacea. Shell-fish are the next most conspicuous inhabitants. Molluscs are already well represented, but the more numerous are the more elementary Brachiopods ("lampshells"), which come next to the Trilobites in number and variety. Worms (or Annelids) wind in and out of the mud, leaving their tracks and tubes for later ages. Strange ball or cup-shaped little animals, with a hard frame, mounted on stony stalks and waving irregular arms to draw in the food-bearing water, are the earliest representatives of the Echinoderms. Some of these Cystids will presently blossom into the wonderful sea-lily population of the next age, some are already quitting their stalks, to become the free-moving star-fish, of which a primitive specimen has been found in the later Cambrian. Large jelly-fishes (of which casts are preserved) swim in the water; coral-animals lay their rocky foundations, but do not as yet form reefs; coarse sponges rise from the floor; and myriads of tiny Radiolaria and Thalamophores, with shells of flint and lime, float at the surface or at various depths. This slight sketch of the Cambrian population shows us that living things had already reached a high level of development. Their story evidently goes back, for millions of years, deep into those mists of the Archaean age which we were unable to penetrate. We turn therefore to the zoologist to learn what he can tell us of the origin and family-relations of these Cambrian animals, and will afterwards see how they are climbing to higher levels under the eye of the geologist. At the basis of the living world of to-day is a vast population of minute, generally microscopic, animals and plants, which are popularly known as "microbes." Each consists, in scientific language, of one cell. It is now well known that the bodies of the larger animals and plants are made up of millions of these units of living matter, or cells--the atoms of the organic world--and I need not enlarge on it. But even a single cell lends itself to infinite variety of shape, and we have to penetrate to the very lowest level of this luxuriant world of one-celled organisms to obtain some idea of the most primitive living things. Properly speaking, there were no "first living things." It cannot be doubted by any student of nature that the microbe developed so gradually that it is as impossible to fix a precise term for the beginning of life as it is to say when the night ends and the day begins. In the course of time little one-celled living units appeared in the waters of the earth, whether in the shallow shore waters or on the surface of the deep is a matter of conjecture. We are justified in concluding that they were at least as rudimentary in structure and life as the lowest inhabitants of nature to-day. The distinction of being the lowest known living organisms should, I think, be awarded to certain one-celled vegetal organisms which are very common in nature. Minute simple specks of living matter, sometimes less than the five-thousandth of an inch in diameter, these lowly Algae are so numerous that it is they, in their millions, which cover moist surfaces with the familiar greenish or bluish coat. They have no visible organisation, though, naturally, they must have some kind of structure below the range of the microscope. Their life consists in the absorption of food-particles, at any point of their surface, and in dividing into two living microbes, instead of dying, when their bulk increases. A very lowly branch of the Bacteria (Nitrobacteria) sometimes dispute their claim to the lowest position in the hierarchy of living nature, but there is reason to suspect that these Bacteria may have degenerated from a higher level. Here we have a convenient starting-point for the story of life, and may now trace the general lines of upward development. The first great principle to be recognised is the early division of these primitive organisms into two great classes, the moving and the stationary. The clue to this important divergence is found in diet. With exceptions on both sides, we find that the non-moving microbes generally feed on inorganic matter, which they convert into plasm; the moving microbes generally feed on ready-made plasm--on the living non-movers, on each other, or on particles of dead organic matter. Now, inorganic food is generally diffused in the waters, so that the vegetal feeders have no incentive to develop mobility. On the other hand, the power to move in search of their food, which is not equally diffused, becomes a most important advantage to the feeders on other organisms. They therefore develop various means of locomotion. Some flow or roll slowly along like tiny drops of oil on an inclined surface; others develop minute outgrowths of their substance, like fine hairs, which beat the water as oars do. Some of them have one strong oar, like the gondolier (but in front of the boat); others have two or more oars; while some have their little flanks bristling with fine lashes, like the flanks of a Roman galley. If we imagine this simple principle at work for ages among the primitive microbes, we understand the first great division of the living world, into plants and animals. There must have been a long series of earlier stages below the plant and animal. In fact, some writers insist that the first organisms were animal in nature, feeding on the more elementary stages of living matter. At last one type develops chlorophyll (the green matter in leaves), and is able to build up plasm out of inorganic matter; another type develops mobility, and becomes a parasite on the plant world. There is no rigid distinction of the two worlds. Many microscopic plants move about just as animals do, and many animals live on fixed stalks; while many plants feed on organic matter. There is so little "difference of nature" between the plant and the animal that the experts differ in classifying some of these minute creatures. In fact, we shall often find plants and animals crossing the line of division. We shall find animals rooting themselves to the floor, like plants, though they will generally develop arms or streamers for bringing the food to them; and we shall find plants becoming insect-catchers. All this merely shows that the difference is a natural tendency, which special circumstances may overrule. It remains true that the great division of the organic world is due to a simple principle of development; difference of diet leads to difference of mobility. But this simple principle will have further consequences of a most important character. It will lead to the development of mind in one half of living nature and leave it undeveloped in the other. Mind, as we know it in the lower levels of life, is not confined to the animal at all. Many even of the higher plants are very delicately sensitive to stimulation, and at the lowest level many plants behave just like animals. In other words, this sensitiveness to stimuli, which is the first form of mind, is distributed according to mobility. To the motionless organism it is no advantage; to the pursuing and pursued organism it is an immense advantage, and is one of the chief qualities for natural selection to foster. For the moment, however, we must glance at the operation of this and other natural principles in the evolution of the one-celled animals and plants, which we take to represent the primitive population of the earth. As there are tens of thousands of different species even of "microbes," it is clear that we must deal with them in a very summary way. The evolution of the plant I reserve for a later chapter, and I must be content to suggest the development of one-celled animals on very broad lines. When some of the primitive cells began to feed on each other, and develop mobility, it is probable that at least two distinct types were evolved, corresponding to the two lowest animal organisms in nature to-day. One of these is a very minute and very common (in vases of decaying flowers, for instance) speck of plasm, which moves about by lashing the water with a single oar (flagellum), or hair-like extension of its substance. This type, however, which is known as the Flagellate, may be derived from the next, which we will take as the primitive and fundamental animal type. It is best seen in the common and familiar Amoeba, a minute sac of liquid or viscid plasm, often not more than a hundredth of an inch in diameter. As its "skin" is merely a finer kind of the viscous plasm, not an impenetrable membrane, it takes in food at any part of its surface, makes little "stomachs," or temporary cavities, round the food at any part of its interior, ejects the useless matter at any point, and thrusts out any part of its body as temporary "arms" or "feet." Now it is plain that in an age of increasing microbic cannibalism the toughening of the skin would be one of the first advantages to secure survival, and this is, in point of fact, almost the second leading principle in early development. Naturally, as the skin becomes firmer, the animal can no longer, like the Amoeba, take food at, or make limbs of, any part of it. There must be permanent pores in the membrane to receive food or let out rays of the living substance to act as oars or arms. Thus we get an immense variety amongst these Protozoa, as the one-celled animals are called. Some (the Flagellates) have one or two stout oars; some (the Ciliates) have numbers of fine hairs (or cilia). Some have a definite mouth-funnel, but no stomach, and cilia drawing the water into it. Some (Vorticella, etc.), shrinking from the open battlefield, return to the plant-principle, live on stalks, and have wreaths of cilia round the open mouth drawing the water to them. Some (the Heliozoa) remain almost motionless, shooting out sticky rays of their matter on every side to catch the food. Some form tubes to live in; some (Coleps) develop horny plates for armour; and others develop projectiles to pierce their prey (stinging threads). This miniature world is full of evolutionary interest, but it is too vast for detailed study here. We will take one group, which we know to have been already developed in the Cambrian, and let a study of its development stand for all. In every lecture or book on "the beauties of the microscope" we find, and are generally greatly puzzled by, minute shells of remarkable grace and beauty that are formed by some of these very elementary animals They are the Radiolaria (with flinty shells, as a rule) and the Thalamophora (with chalk frames). Evolution furnishes a simple key to their remarkable structure. As we saw, one of the early requirements to be fostered by natural selection in the Archaean struggle for life was a "thick skin," and the thick skin had to be porous to let the animal shoot out its viscid substance in rays and earn its living. This stage above the Amoeba is beautifully illustrated in the sun-animalcules (Heliozoa). Now the lowest types of Radiolaria are of this character. They have no shell or framework at all. The next stage is for the little animal to develop fine irregular threads of flint in its skin, a much better security against the animal-eater. These animalcules, it must be recollected, are bits of almost pure plasm, and, as they live in crowds, dividing and subdividing, but never dying, make excellent mouthfuls for a small feeder. Those with the more flint in their skins were the more apt to survive and "breed." The threads of flint increase until they form a sort of thorn-thicket round a little social group, or a complete lattice round an individual body. Next, spikes or spines jut out from the lattice, partly for additional protection, partly to keep the little body afloat at the surface of the sea. In this way we get a bewildering variety and increasing complexity of forms, ascending in four divergent lines from the naked ancestral type to the extreme grace and intricacy of the Calocyclas monumentum or the Lychnaspis miranda. These, however, are rare specimens in the 4000 species of Radiolaria. I have hundreds of them, on microscopic slides, which have no beauty and little regularity of form. We see a gradual evolution, on utilitarian principles, as we run over the thousands of forms; and, when we recollect the inconceivable numbers in which these little animals have lived and struggled for life--passively--during tens of millions of years, we are not surprised at the elaborate protective frames of the higher types. The Thalamophores, the sister-group of one-celled animals which largely compose our chalk and much of our limestone, are developed on the same principle. The earlier forms seem to have lived in a part of the ocean where silica was scarce, and they absorbed and built their protective frames of lime. In the simpler types the frame is not unlike a wide-necked bottle, turned upside-down. In later forms it takes the shape of a spirally coiled series of chambers, sometimes amounting to several thousand. These wonderful little houses are not difficult to understand. The original tiny animal covers itself with a coat of lime. It feeds, grows, and bulges out of its chamber. The new part of its flesh must have a fresh coat, and the process goes on until scores, or hundreds, or even thousands, of these tiny chambers make up the spiral shell of the morsel of living matter. With this brief indication of the mechanical principles which have directed the evolution of two of the most remarkable groups of the one-celled animals we must be content, or the dimensions of this volume will not enable us even to reach the higher and more interesting types. We must advance at once to the larger animals, whose bodies are composed of myriads of cells. The social tendency which pervades the animal world, and the evident use of that tendency, prepare us to understand that the primitive microbes would naturally come in time to live in clusters. Union means effectiveness in many ways, even when it does not mean strength. We have still many loose associations of one-celled animals in nature, illustrating the approach to a community life. Numbers of the Protozoa are social; they live either in a common jelly-like matrix, or on a common stalk. In fact, we have a singularly instructive illustration of the process in the evolution of the sponges. It is well known that the horny texture to which we commonly give the name of sponge is the former tenement and shelter of a colony of one-celled animals, which are the real Sponges. In other groups the structure is of lime; in others, again, of flinty material. Now, the Sponges, as we have them to-day, are so varied, and start from so low a level, that no other group of animals "illustrates so strikingly the theory of evolution," as Professor Minchin says. We begin with colonies in which the individuals are (as in Proterospongia) irregularly distributed in their jelly-like common bed, each animal lashing the water, as stalked Flagellates do, and bringing the food to it. Such a colony would be admirable food for an early carnivore, and we soon find the protective principle making it less pleasant for the devourer. The first stage may be--at least there are such Sponges even now--that the common bed is strewn or sown with the cast shells of Radiolaria. However that may be, the Sponges soon begin to absorb the silica or lime of the sea-water, and deposit it in needles or fragments in their bed. The deposit goes on until at last an elaborate framework of thorny, or limy, or flinty material is constructed by the one-celled citizens. In the higher types a system of pores or canals lets the food-bearing water pass through, as the animals draw it in with their lashes; in the highest types the animals come still closer together, lining the walls of little chambers in the interior. Here we have a very clear evolutionary transition from the solitary microbe to a higher level, but, unfortunately, it does not take us far. The Sponges are a side-issue, or cul de sac, from the Protozoic world, and do not lead on to the higher. Each one-celled unit remains an animal; it is a colony of unicellulars, not a many-celled body. We may admire it as an instructive approach toward the formation of a many-celled body, but we must look elsewhere for the true upward advance. The next stage is best illustrated in certain spherical colonies of cells like the tiny green Volvox (now generally regarded as vegetal) of our ponds, or Magosphoera. Here the constituent cells merge their individuality in the common action. We have the first definite many-celled body. It is the type to which a moving close colony of one-celled microbes would soon come. The round surface is well adapted for rolling or spinning along in the water, and, as each little cell earns its own living, it must be at the surface, in contact with the water. Thus a hollow, or fluid-filled, little sphere, like the Volvox, is the natural connecting-link between the microbe and the many-celled body, and may be taken to represent the first important stage in its development. The next important stage is also very clearly exhibited in nature, and is more or less clearly reproduced in the embryonic development of all animals. We may imagine that the age of microbes was succeeded by an age of these many-celled larger bodies, and the struggle for life entered upon a new phase. The great principle we have already recognised came into play once more. Large numbers of the many-celled bodies shrank from the field of battle, and adopted the method of the plant. They rooted themselves to the floor of the ocean, and developed long arms or lashes for creating a whirlpool movement in the water, and thus bringing the food into their open mouths. Forfeiting mobility, they have, like the plant, forfeited the greater possibilities of progress, and they remain flowering to-day on the floors of our waters, recalling the next phase in the evolution of early life. Such are the hydra, the polyp, the coral, and the sea-anemone. It is not singular that earlier observers could not detect that they were animals, and they were long known in science as "animal-plants" (Zoophytes). When we look to the common structure of these animals, to find the ancestral type, we must ignore the nerve and muscle-cells which they have developed in some degree. Fundamentally, their body consists of a pouch, with an open mouth, the sides of the pouch consisting of a double layer of cells. In this we have a clue to the next stage of animal development. Take a soft india-rubber ball to represent the first many-celled animal. Press in one half of the ball close upon the other, narrow the mouth, and you have something like the body-structure of the coral and hydra. As this is the course of embryonic development, and as it is so well retained in the lowest groups of the many-celled animals, we take it to be the next stage. The reason for it will become clear on reflection. Division of labour naturally takes place in a colony, and in that way certain cells in the primitive body were confined to the work of digestion. It would be an obvious advantage for these to retire into the interior, leaving the whole external surface free for the adjustment of the animal's relations to the outer world. Again we must refrain from following in detail the development of this new world of life which branches off in the Archaean ocean. The evolution of the Corals alone would be a lengthy and interesting story. But a word must be said about the jelly-fish, partly because the inexpert will be puzzled at the inclusion of so active an animal, and partly because its story admirably illustrates the principle we are studying. The Medusa really descends from one of the plant-like animals of the early Archaean period, but it has abandoned the ancestral stalk, turned upside down, and developed muscular swimming organs. Its past is betrayed in its embryonic development. As a rule the germ develops into a stalked polyp, out of which the free-swimming Medusa is formed. This return to active and free life must have occurred early, as we find casts of large Medusae in the Cambrian beds. In complete harmony with the principle we laid down, the jelly-fish has gained in nerve and sensitiveness in proportion to its return to an active career. But this principle is best illustrated in the other branch of the early many-celled animals, which continued to move about in search of food. Here, as will be expected, we have the main stem of the animal world, and, although the successive stages of development are obscure, certain broad lines that it followed are clear and interesting. It is evident that in a swarming population of such animals the most valuable qualities will be speed and perception. The sluggish Coral needs only sensitiveness enough, and mobility enough, to shrink behind its protecting scales at the approach of danger. In the open water the most speedy and most sensitive will be apt to escape destruction, and have the larger share in breeding the next generation. Imagine a selection on this principle going on for millions of years, and the general result can be conjectured. A very interesting analogy is found in the evolution of the boat. From the clumsy hollowed tree of Neolithic man natural selection, or the need of increasing speed, has developed the elongated, evenly balanced modern boat, with its distinct stem and stern. So in the Archaean ocean the struggle to overtake food, or escape feeders, evolved an elongated two-sided body, with head and tail, and with the oars (cilia) of the one-celled ancestor spread thickly along its flanks. In other words, a body akin to that of the lower water-worms would be the natural result; and this is, in point of fact, the next stage we find in the hierarchy of living nature. Probably myriads of different types of this worm-like organisation were developed, but such animals leave no trace in the rocks, and we can only follow the development by broad analogies. The lowest flat-worms of to-day may represent some of these early types, and as we ascend the scale of what is loosely called "worm" organisation, we get some instructive suggestions of the way in which the various organs develop. Division of labour continues among the colony of cells which make up the body, and we get distinct nerve-cells, muscle-cells, and digestive cells. The nerve-cells are most useful at the head of an organism which moves through the water, just as the look-out peers from the head of the ship, and there they develop most thickly. By a fresh division of labour some of these cells become especially sensitive to light, some to the chemical qualities of matter, some to movements of the water; we have the beginning of the eyes, the nose, and the ears, as simple little depressions in the skin of the head, lined with these sensitive cells. A muscular gullet arises to protect the digestive tube; a simple drainage channel for waste matter forms under the skin; other channels permit the passage of the fluid food, become (in the higher worms) muscular blood-vessels, and begin to contract--somewhat erratically at first--and drive the blood through the system. Here, perhaps, are millions of years of development compressed into a paragraph. But the purpose of this work is chiefly to describe the material record of the advance of life in the earth's strata, and show how it is related to great geological changes. We must therefore abstain from endeavouring to trace the genealogy of the innumerable types of animals which were, until recently, collected in zoology under the heading "Worms." It is more pertinent to inquire how the higher classes of animals, which we found in the Cambrian seas, can have arisen from this primitive worm-like population. The struggle for life in the Archaean ocean would become keener and more exacting with the appearance of each new and more effective type. That is a familiar principle in our industrial world to-day, and we shall find it illustrated throughout our story. We therefore find the various processes of evolution, which we have already seen, now actively at work among the swarming Archaean population, and producing several very distinct types. In some of these struggling organisms speed is developed, together with offensive and defensive weapons, and a line slowly ascends toward the fish, which we will consider later. In others defensive armour is chiefly developed, and we get the lines of the heavy sluggish shell-fish, the Molluscs and Brachiopods, and, by a later compromise between speed and armour, the more active tough-coated Arthropods. In others the plant-principle reappears; the worm-like creature retires from the free-moving life, attaches itself to a fixed base, and becomes the Bryozoan or the Echinoderm. To trace the development of these types in any detail is impossible. The early remains are not preserved. But some clues are found in nature or in embryonic development, and, when the types do begin to be preserved in the rocks, we find the process of evolution plainly at work in them. We will therefore say a few words about the general evolution of each type, and then return to the geological record in the Cambrian rocks. The starfish, the most familiar representative of the Echinoderms, seems very far removed from the kind of worm-like ancestor we have been imagining, but, fortunately, the very interesting story of the starfish is easily learned from the geological chronicle. Reflect on the flower-like expansion of its arms, and then imagine it mounted on a stalk, mouth side upward, with those arms--more tapering than they now are--waving round the mouth. That, apparently, was the past of the starfish and its cousins. We shall see that the earliest Echinoderms we know are cup-shaped structures on stalks, with a stiff, limy frame and (as in all sessile animals) a number of waving arms round the mouth. In the next geological age the stalk will become a long and flexible arrangement of muscles and plates of chalk, the cup will be more perfectly compacted of chalky plates, and the five arms will taper and branch until they have an almost feathery appearance; and the animal will be considered a "sea-lily" by the early geologist. The evidence suggests that both the free-moving and the stalked Echinoderms descend from a common stalked Archaean ancestor. Some primitive animal abandoned the worm-like habit, and attached itself, like a polyp, to the floor. Like all such sessile animals, it developed a wreath of arms round the open mouth. The "sea-cucumber" (Holothurian) seems to be a type that left the stalk, retaining the little wreath of arms, before the body was heavily protected and deformed. In the others a strong limy skeleton was developed, and the nerves and other organs were modified in adaptation to the bud-like or flower-like structure. Another branch of the family then abandoned the stalk, and, spreading its arms flat, and gradually developing in them numbers of little "feet" (water-tubes), became the starfish. In the living Comatula we find a star passing through the stalked stage in its early development, when it looks like a tiny sea-lily. The sea-urchin has evolved from the star by folding the arms into a ball. [*] * See the section on Echinoderms, by Professor MacBride, in the "Cambridge Natural History," I. The Bryozoa (sea-mats, etc.) are another and lower branch of the primitive active organisms which have adopted a sessile life. In the shell-fish, on the other hand, the principle of armour-plating has its greatest development. It is assuredly a long and obscure way that leads from the ancestral type of animal we have been describing to the headless and shapeless mussel or oyster. Such a degeneration is, however, precisely what we should expect to find in the circumstances. Indeed, the larva, of many of the headless Molluscs have a mouth and eyes, and there is a very common type of larva--the trochosphere--in the Mollusc world which approaches the earlier form of some of the higher worms. The Molluscs, as we shall see, provide some admirable illustrations of the process of evolution. In some of the later fossilised specimens (Planorbis, Paludina, etc.) we can trace the animal as it gradually passes from one species to another. The freshening of the Caspian Sea, which was an outlying part of the Mediterranean quite late in the geological record, seems to have evolved several new genera of Molluscs. Although, therefore, the remains are not preserved of those primitive Molluscs in which we might see the protecting shell gradually thickening, and deforming the worm-like body, we are not without indications of the process. Two unequal branches of the early wormlike organisms shrank into strong protective shells. The lower branch became the Brachiopods; the more advanced branch the Molluscs. In the Mollusc world, in turn, there are several early types developed. In the Pelecypods (or Lamellibranchs--the mussel, oyster, etc.) the animal retires wholly within its fortress, and degenerates. The Gastropods (snails, etc.) compromise, and retain a certain amount of freedom, so that they degenerate less. The highest group, the Cephalopods, "keep their heads," in the literal sense, and we shall find them advancing from form to form until, in the octopus of a later age, they discard the ancestral shell, and become the aristocrats of the Mollusc kingdom. The last and most important line that led upward from the chaos of Archaean worms is that of the Arthropods. Its early characteristic was the acquisition of a chitinous coat over the body. Embryonic indications show that this was at first a continuous shield, but a type arose in which the coat broke into sections covering each segment of the body, giving greater freedom of movement. The shield, in fact, became a fine coat of mail. The Trilobite is an early and imperfect experiment of the class, and the larva of the modern king-crab bears witness that it has not perished without leaving descendants. How later Crustacea increase the toughness of the coat by deposits of lime, and lead on to the crab and lobster, and how one early branch invades the land, develops air-breathing apparatus, and culminates in the spiders and insects, will be considered later. We shall see that there is most remarkable evidence connecting the highest of the Arthropods, the insect, with a remote Annelid ancestor. We are thus not entirely without clues to the origin of the more advanced animals we find when the fuller geological record begins. Further embryological study, and possibly the discovery of surviving primitive forms, of which Central Africa may yet yield a number, may enlarge our knowledge, but it is likely to remain very imperfect. The fossil records of the long ages during which the Mollusc, the Crustacean, and the Echinoderm slowly assumed their characteristic forms are hopelessly lost. But we are now prepared to return to the record which survives, and we shall find the remaining story of the earth a very ample and interesting chronicle of evolution. CHAPTER VII. THE PASSAGE TO THE LAND Slender as our knowledge is of the earlier evolution of the Invertebrate animals, we return to our Cambrian population with greater interest. The uncouth Trilobite and its livelier cousins, the sluggish, skulking Brachiopod and Mollusc, the squirming Annelids, and the plant-like Cystids, Corals, and Sponges are the outcome of millions of years of struggle. Just as men, when their culture and their warfare advanced, clothed themselves with armour, and the most completely mailed survived the battle, so, generation after generation, the thicker and harder-skinned animals survived in the Archaean battlefield, and the Cambrian age opened upon the various fashions of armour that we there described. But, although half the story of life is over, organisation is still imperfect and sluggish. We have now to see how it advances to higher levels, and how the drama is transferred from the ocean to a new and more stimulating environment. The Cambrian age begins with a vigorous move on the part of the land. The seas roll back from the shores of the "lost Atlantis," and vast regions are laid bare to the sun and the rains. In the bays and hollows of the distant shores the animal survivors of the great upheaval adapt themselves to their fresh homes and continue the struggle. But the rivers and the waves are at work once more upon the land, and, as the Cambrian age proceeds, the fringes of the continents are sheared, and the shore-life steadily advances upon the low-lying land. By the end of the Cambrian age a very large proportion of the land is covered with a shallow sea, in which the debris of its surface is deposited. The levelling continues through the next (Ordovician) period. Before its close nearly the whole of the United States and the greater part of Canada are under water, and the new land that had appeared on the site of Europe is also for the most part submerged. The present British Isles are almost reduced to a strip of north-eastern Ireland, the northern extremity of Scotland, and large islands in the south-west and centre of England. We have already seen that these victories of the sea are just as stimulating, in a different way, to animals as the victories of the land. American geologists are tracing, in a very instructive way, the effect on that early population of the encroachment of the sea. In each arm of the sea is a distinctive fauna. Life is still very parochial; the great cosmopolitans, the fishes, have not yet arrived. As the land is revelled, the arms of the sea approach each other, and at last mingle their waters and their populations, with stimulating effect. Provincial characters are modified, and cosmopolitan characters increase in the great central sea of America. The vast shallow waters provide a greatly enlarged theatre for the life of the time, and it flourishes enormously. Then, at the end of the Ordovician, the land begins to rise once more. Whether it was due to a fresh shrinking of the crust, or to the simple process we have described, or both, we need not attempt to determine; but both in Europe and America there is a great emergence of land. The shore-tracts and the shallow water are narrowed, the struggle is intensified in them, and we pass into the Silurian age with a greatly reduced number but more advanced variety of animals. In the Silurian age the sea advances once more, and the shore-waters expand. There is another great "expansive evolution" of life. But the Silurian age closes with a fresh and very extensive emergence of the land, and this time it will have the most important consequences. For two new things have meantime appeared on the earth. The fish has evolved in the waters, and the plant, at least, has found a footing on the land. These geological changes which we have summarised and which have been too little noticed until recently in evolutionary studies, occupied 7,000,000 years, on the lowest estimate, and probably twice that period. The impatient critic of evolutionary hypotheses is apt to forget the length of these early periods. We shall see that in the last two or three million years of the earth's story most extraordinary progress has been made in plant and animal development, and can be very fairly traced. How much advance should we allow for these seven or fourteen million years of swarming life and changing environments? We cannot nearly cover the whole ground of paleontology for the period, and must be content to notice some of the more interesting advances, and then deal more fully with the evolution of the fish, the forerunner of the great land animals. The Trilobite was the most arresting figure in the Cambrian sea, and its fortunes deserve a paragraph. It reaches its climax in the Ordovician sea, and then begins to decline, as more powerful animals come upon the scene. At first (apparently) an eyeless organism, it gradually develops compound eyes, and in some species the experts have calculated that there were 15,000 facets to each eye. As time goes on, also, the eye stands out from the head on a kind of stalk, giving a wider range of vision. Some of the more sluggish species seem to have been able to roll themselves up, like hedgehogs, in their shells, when an enemy approached. But another branch of the same group (Crustacea) has meantime advanced, and it gradually supersedes the dwindling Trilobites. Toward the close of the Silurian great scorpion-like Crustaceans (Pterygotus, Eurypterus, etc.) make their appearance. Their development is obscure, but it must be remembered that the rocks only give the record of shore-life, and only a part of that is as yet opened by geology. Some experts think that they were developed in inland waters. Reaching sometimes a length of five or six feet, with two large compound eyes and some smaller eye-spots (ocelli), they must have been the giants of the Silurian ocean until the great sharks and other fishes appeared. The quaint stalked Echinoderm which also we noticed in the Cambrian shallows has now evolved into a more handsome creature, the sea-lily. The cup-shaped body is now composed of a large number of limy plates, clothed with flesh; the arms are long, tapering, symmetrical, and richly fringed; the stalk advances higher and higher, until the flower-like animal sometimes waves its feathery arms from the top of a flexible pedestal composed of millions of tiny chalk disks. Small forests of these sea-lilies adorn the floor of the Silurian ocean, and their broken and dead frames form whole beds of limestone. The primitive Cystids dwindle and die out in the presence of such powerful competitors. Of 250 species only a dozen linger in the Silurian strata, though a new and more advanced type--the Blastoid--holds the field for a time. It is the age of the Crinoids or sea-lilies. The starfish, which has abandoned the stalk, does not seem to prosper as yet, and the brittle-star appears. Their age will come later. No sea-urchins or sea-cucumbers (which would hardly be preserved) are found as yet. It is precisely the order of appearance which our theory of their evolution demands. The Brachiopods have passed into entirely new and more advanced species in the many advances and retreats of the shores, but the Molluscs show more interesting progress. The commanding group from the start is that of the Molluscs which have "kept their head," the Cephalopods, and their large shells show a most instructive evolution. The first great representative of the tribe is a straight-shelled Cephalopod, which becomes "the tyrant and scavenger of the Silurian ocean" (Chamberlin). Its tapering, conical shell sometimes runs to a length of fifteen feet, and a diameter of one foot. It would of itself be an important evolutionary factor in the primitive seas, and might explain more than one advance in protective armour or retreat into heavy shells. As the period advances the shell begins to curve, and at last it forms a close spiral coil. This would be so great an advantage that we are not surprised to find the coiled type (Goniatites) gain upon and gradually replace the straight-shelled types (Orthoceratites). The Silurian ocean swarms with these great shelled Cephalopods, of which the little Nautilus is now the only survivor. We will not enlarge on the Sponges and Corals, which are slowly advancing toward the higher modern types. Two new and very powerful organisms have appeared, and merit the closest attention. One is the fish, the remote ancestor of the birds and mammals that will one day rule the earth. The other may be the ancestor of the fish itself, or it may be one of the many abortive outcomes and unsuccessful experiments of the stirring life of the time. And while these new types are themselves a result of the great and stimulating changes which we have reviewed and the incessant struggle for food and safety, they in turn enormously quicken the pace of development. The Dreadnought appears in the primitive seas; the effect on the fleets of the world of the evolution of our latest type of battleship gives us a faint idea of the effect, on all the moving population, of the coming of these monsters of the deep. The age had not lacked incentives to progress; it now obtains a more terrible and far-reaching stimulus. To understand the situation let us see how the battle of land and sea had proceeded. The Devonian Period had opened with a fresh emergence of the land, especially in Europe, and great inland seas or lakes were left in the hollows. The tincture of iron which gives a red colour to our characteristic Devonian rocks, the Old Red Sandstone, shows us that the sand was deposited in inland waters. The fish had already been developed, and the Devonian rocks show it swarming, in great numbers and variety, in the enclosed seas and round the fringe of the continents. The first generation was a group of strange creatures, half fish and half Crustacean, which are known as the Ostracoderms. They had large armour-plated heads, which recall the Trilobite, and suggest that they too burrowed in the mud of the sea or (as many think) of the inland lakes, making havoc among the shell-fish, worms, and small Crustacea. The hind-part of their bodies was remarkably fish-like in structure. But they had no backbone--though we cannot say whether they may not have had a rod of cartilage along the back--and no articulated jaws like the fish. Some regard them as a connecting link between the Crustacea and the fishes, but the general feeling is that they were an abortive development in the direction of the fish. The sharks and other large fishes, which have appeared in the Silurian, easily displace these clumsy and poor-mouthed competitors One almost thinks of the aeroplane superseding the navigable balloon. Of the fishes the Arthrodirans dominated the inland seas (apparently), while the sharks commanded the ocean. One of the Arthrodirans, the Dinichthys ("terrible fish"), is the most formidable fish known to science. It measured twenty feet from snout to tail. Its monstrous head, three feet in width, was heavily armoured, and, instead of teeth, its great jaws, two feet in length, were sharpened, and closed over the victim like a gigantic pair of clippers. The strongly plated heads of these fishes were commonly a foot or two feet in width. Life in the waters became more exacting than ever. But the Arthrodirans were unwieldy and sluggish, and had to give way before more progressive types. The toothed shark gradually became the lord of the waters. The early shark ate, amongst other things, quantities of Molluscs and Brachiopods. Possibly he began with Crustacea; in any case the practice of crunching shellfish led to a stronger and stronger development of the hard plate which lined his mouth. The prickles of the plate grew larger and harder, until--as may be seen to-day in the mouth of a young shark--the cavity was lined with teeth. In the bulk of the Devonian sharks these developed into what are significantly called "pavement teeth." They were solid plates of enamel, an inch or an inch and a half in width, with which the monster ground its enormous meals of Molluscs, Crustacea, sea-weed, etc. A new and stimulating element had come into the life of the invertebrate world. Other sharks snapped larger victims, and developed the teeth on the edges of their jaws, to the sacrifice of the others, until we find these teeth in the course of time solid triangular masses of enamel, four or five inches long, with saw-like edges. Imagine these terrible mouths--the shears of the Arthrodiran, and the grindstones and terrible crescents of the giant sharks--moving speedily amongst the crowded inhabitants of the waters, and it is easy to see what a stimulus to the attainment of speed and of protective devices was given to the whole world of the time. What was the origin of the fish? Here we are in much the same position as we were in regard to the origin of the higher Invertebrates. Once the fish plainly appears upon the scene it is found to be undergoing a process of evolution like all other animals. The vast majority of our fishes have bony frames (or are Teleosts); the fishes of the Devonian age nearly all have frames of cartilage, and we know from embryonic development that cartilage is the first stage in the formation of bone. In the teeth and tails, also, we find a gradual evolution toward the higher types. But the earlier record is, for reasons I have already given, obscure; and as my purpose is rather to discover the agencies of evolution than to strain slender evidence in drawing up pedigrees, I need only make brief reference to the state of the problem. Until comparatively recent times the animal world fell into two clearly distinct halves, the Vertebrates and the Invertebrates. There were several anatomical differences between the two provinces, but the most conspicuous and most puzzling was the backbone. Nowhere in living nature or in the rocks was any intermediate type known between the backboned and the non-backboned animal. In the course of the nineteenth century, however, several animals of an intermediate type were found. The sea-squirt has in its early youth the line of cartilage through the body which, in embryonic development, represents the first stage of the backbone; the lancelet and the Appendicularia have a rod of cartilage throughout life; the "acorn-headed worm" shows traces of it. These are regarded as surviving specimens of various groups of animals which, in early times, fell between the Invertebrate and Vertebrate worlds, and illustrate the transition. With their aid a genealogical tree was constructed for the fish. It was assumed that some Cambrian or Silurian Annelid obtained this stiffening rod of cartilage. The next advantage--we have seen it in many cases--was to combine flexibility with support. The rod was divided into connected sections (vertebrae), and hardened into bone. Besides stiffening the body, it provided a valuable shelter for the spinal cord, and its upper part expanded into a box to enclose the brain. The fins were formed of folds of skin which were thrown off at the sides and on the back, as the animal wriggled through the water. They were of use in swimming, and sections of them were stiffened with rods of cartilage, and became the pairs of fins. Gill slits (as in some of the highest worms) appeared in the throat, the mouth was improved by the formation of jaws, and--the worm culminated in the shark. Some experts think, however, that the fish developed directly from a Crustacean, and hold that the Ostracoderms are the connecting link. A close discussion of the anatomical details would be out of place here, [*] and the question remains open for the present. Directly or indirectly, the fish is a descendant of some Archaean Annelid. It is most probable that the shark was the first true fish-type. There are unrecognisable fragments of fishes in the Ordovician and Silurian rocks, but the first complete skeletons (Lanarkia, etc.) are of small shark- like creatures, and the low organisation of the group to which the shark belongs, the Elasmobranchs, makes it probable that they are the most primitive. Other remains (Palaeospondylus) show that the fish-like lampreys had already developed. * See, especially, Dr. Gaskell's "Origin of Vertebrates" (1908). Two groups were developed from the primitive fish, which have great interest for us. Our next step, in fact, is to trace the passage of the fish from the water to the land, one of the most momentous chapters in the story of life. To that incident or accident of primitive life we owe our own existence and the whole development of the higher types of animals. The advance of natural history in modern times has made this passage to the land easy to understand. Not only does every frog reenact it in the course of its development, but we know many fishes that can live out of water. There is an Indian perch--called the "climbing perch," but it has only once been seen by a European to climb a tree--which crosses the fields in search of another pool, when its own pool is evaporating. An Indian marine fish (Periophthalmus) remains hunting on the shore when the tide goes out. More important still, several fishes have lungs as well as gills. The Ceratodus of certain Queensland rivers has one lung; though, I was told by the experts in Queensland, it is not a "mud-fish," and never lives in dry mud. However, the Protopterus of Africa and the Lepidosiren of South America have two lungs, as well as gills, and can live either in water or, in the dry season, on land. When the skeletons of fishes of the Ceratodus type were discovered in the Devonian rocks, it was felt that we had found the fish-ancestor of the land Vertebrates, but a closer anatomical examination has made this doubtful. The Devonian lung-fish has characters which do not seem to lead on to the Amphibia. The same general cause probably led many groups to leave the water, or adapt themselves to living on land as well as in water, and the abundant Dipoi or Dipneusts ("double-breathers") of the Devonian lakes are one of the chief of these groups, which have luckily left descendants to our time. The ancestors of the Amphibia are generally sought amongst the Crossopterygii, a very large group of fishes in Devonian times, with very few representatives to-day. It is more profitable to investigate the process itself than to make a precarious search for the actual fish, and, fortunately, this inquiry is more hopeful. The remains that we find make it probable that the fish left the water about the beginning of the Devonian or the end of the Silurian. Now this period coincides with two circumstances which throw a complete light on the step; one is the great rise of the land, catching myriads of fishes in enclosed inland seas, and the other is the appearance of formidable carnivores in the waters. As the seas evaporated [*] and the great carnage proceeded, the land, which was already covered with plants and inhabited by insects, offered a safe retreat for such as could adopt it. Emigration to the land had been going on for ages, as we shall see. Curious as it must seem to the inexpert, the fishes, or some of them, were better prepared than most other animals to leave the water. The chief requirement was a lung, or interior bag, by which the air could be brought into close contact with the absorbing blood vessels. Such a bag, broadly speaking, most of the fishes possess in their floating-bladder: a bag of gas, by compressing or expanding which they alter their specific gravity in the water. In some fishes it is double; in some it is supplied with blood-vessels; in some it is connected by a tube with the gullet, and therefore with the atmosphere. * It is now usually thought that the inland seas were the theatre of the passage to land. I must point out, however, that the wide distribution of our Dipneusts, in Australia, tropical Africa, and South America, suggests that they were marine though they now live in fresh water. But we shall see that a continent united the three regions at one time, and it may afford some explanation. Thus we get very clear suggestions of the transition from water to land. We must, of course, conceive it as a slow and gradual adaptation. At first there may have been a rough contrivance for deriving oxygen directly and partially from the atmosphere, as the water of the lake became impure. So important an advantage would be fostered, and, as the inland sea became smaller, or its population larger or fiercer, the fishes with a sufficiently developed air-breathing apparatus passed to the land, where, as yet, they would find no serious enemy. The fact is beyond dispute; the theory of how it occurred is plausible enough; the consequences were momentous. Great changes were preparing on the land, and in a comparatively short time we shall find its new inhabitant subjected to a fierce test of circumstances that will carry it to an enormously higher level than life had yet reached. I have said that the fact of this transition to the land is beyond dispute. The evidence is very varied, but need not all be enlarged upon here. The widespread Dipneust fishes of the Devonian rocks bear strong witness to it, and the appearance of the Amphibian immediately afterwards makes it certain. The development of the frog is a reminiscence of it, on the lines of the embryonic law which we saw earlier. An animal, in its individual development, more or less reproduces the past phases of its ancestry. So the free-swimming jelly-fish begins life as a fixed polyp; a kind of star-fish (Comatula) opens its career as a stalked sea-lily; the gorgeous dragon-fly is at first an uncouth aquatic animal, and the ethereal butterfly a worm-like creature. But the most singular and instructive of all these embryonic reminiscences of the past is found in the fact that all the higher land-animals of to-day clearly reproduce a fish-stage in their embryonic development. In the third and fourth weeks of development the human embryo shows four (closed) slits under the head, with corresponding arches. The bird, the dog, the horse--all the higher land animals, in a word, pass through the same phase. The suggestion has been made that these structures do not recall the gill-slits and gill-arches of the fish, but are folds due to the packing of the embryo in the womb. In point of fact, they appear just at the time when the human embryo is only a fifth of an inch long, and there is no such compression. But all doubt as to their interpretation is dispelled when we remove the skin and examine the heart and blood-vessels. The heart is up in the throat, as in the fish, and has only two chambers, as in the fish (not four, as in the bird and mammal); and the arteries rise in five pairs of arches over the swellings in the throat, as they do in the lower fish, but do not in the bird and mammal. The arrangement is purely temporary--lasting only a couple of weeks in the human embryo--and purposeless. Half these arteries will disappear again. They quite plainly exist to supply fine blood-vessels for breathing at the gill-clefts, and are never used, for the embryo does not breathe, except through the mother. They are a most instructive reminder of the Devonian fish which quitted its element and became the ancestor of all the birds and mammals of a later age. Several other features of man's embryonic development--the budding of the hind limbs high up, instead of at the base of, the vertebral column, the development of the ears, the nose, the jaws, etc.--have the same lesson, but the one detailed illustration will suffice. The millions of years of stimulating change and struggle which we have summarised have resulted in the production of a fish which walks on four limbs (as the South American mud-fish does to-day), and breathes the atmosphere. We have been quite unable to follow the vast changes which have meantime taken place in its organisation. The eyes, which were mere pits in the skin, lined with pigment cells, in the early worm, now have a crystalline lens to concentrate the light and define objects on the nerve. The ears, which were at first similar sensitive pits in the skin, on which lay a little stone whose movements gave the animal some sense of direction, are now closed vesicles in the skull, and begin to be sensitive to waves of sound. The nose, which was at first two blind, sensitive pits in the skin of the head, now consists of two nostrils opening into the mouth, with an olfactory nerve spreading richly over the passages. The brain, which was a mere clump of nerve-cells connecting the rough sense-impressions, is now a large and intricate structure, and already exhibits a little of that important region (the cerebrum) in which the varied images of the outside world are combined. The heart, which was formerly was a mere swelling of a part of one of the blood-vessels, now has two chambers. We cannot pursue these detailed improvements of the mechanism, as we might, through the ascending types of animals. Enough if we see more or less clearly how the changes in the face of the earth and the rise of its successive dynasties of carnivores have stimulated living things to higher and higher levels in the primitive ocean. We pass to the clearer and far more important story of life on land, pursuing the fish through its continuous adaptations to new conditions until, throwing out side-branches as it progresses, it reaches the height of bird and mammal life. CHAPTER VIII. THE COAL-FOREST With the beginning of life on land we open a new and more important volume of the story of life, and we may take the opportunity to make clearer certain principles or processes of development which we may seem hitherto to have taken for granted. The evolutionary work is too often a mere superficial description of the strange and advancing classes of plants and animals which cross the stage of geology. Why they change and advance is not explained. I have endeavoured to supply this explanation by putting the successive populations of the earth in their respective environments, and showing the continuous and stimulating effect on them of changes in those environments. We have thus learned to decipher some lines of the decalogue of living nature. "Thou shalt have a thick armour," "Thou shalt be speedy," "Thou shalt shelter from the more powerful," are some of the laws of primeval life. The appearance of each higher and more destructive type enforces them with more severity; and in their observance animals branch outward and upward into myriads of temporary or permanent forms. But there is no consciousness of law and no idea of evading danger. There is not even some mysterious instinct "telling" the animal, as it used to be said, to do certain things. It is, in fact, not strictly accurate to say that a certain change in the environment stimulates animals to advance. Generally speaking, it does not act on the advancing at all, but on the non-advancing, which it exterminates. The procedure is simple, tangible, and unconscious. Two invading arms of the sea meet and pour together their different waters and populations. The habits, the foods, and the enemies of many types of animals are changed; the less fit for the new environment die first, the more fit survive longest and breed most of the new generation. It is so with men when they migrate to a more exacting environment, whether a dangerous trade or a foreign clime. Again, take the case of the introduction of a giant Cephalopod or fish amongst a population of Molluscs and Crustacea. The toughest, the speediest, the most alert, the most retiring, or the least conspicuous, will be the most apt to survive and breed. In hundreds or thousands of generations there will be an enormous improvement in the armour, the speed, the sensitiveness, the hiding practices, and the protective colours, of the animals which are devoured. The "natural selection of the fittest" really means the "natural destruction of the less fit." The only point assumed in this is that the young of an animal or plant tend to differ from each other and from their parents. Darwin was content to take this as a fact of common observation, as it obviously is, but later science has thrown some light on the causes of these variations. In the first place, the germs in the parent's body may themselves be subject to struggle and natural selection, and not share equally in the food-supply. Then, in the case of the higher animals (or the majority of animals), there is a clear source of variation in the fact that the mature germ is formed of certain elements from two different parents, four grandparents, and so on. In the case of the lower animals the germs and larvae float independently in the water, and are exposed to many influences. Modern embryologists have found, by experiment, that an alteration of the temperature or the chemical considerable effect on eggs and larvae. Some recent experiments have shown that such changes may even affect the eggs in the mother's ovary. These discoveries are very important and suggestive, because the geological changes which we are studying are especially apt to bring about changes of temperature and changes in the freshness or saltiness of water. Evolution is, therefore, not a "mere description" of the procession of living things; it is to a great extent an explanation of the procession. When, however, we come to apply these general principles to certain aspects of the advance in organisation we find fundamental differences of opinion among biologists, which must be noted. As Sir E. Ray Lankester recently said, it is not at all true that Darwinism is questioned in zoology to-day. It is true only that Darwin was not omniscient or infallible, and some of his opinions are disputed. Let me introduce the subject with a particular instance of evolution, the flat-fish. This animal has been fitted to survive the terrible struggle in the seas by acquiring such a form that it can lie almost unseen upon the floor of the ocean. The eye on the under side of the body would thus be useless, but a glance at a sole or plaice in a fishmonger's shop will show that this eye has worked upward to the top of the head. Was the eye shifted by the effort and straining of the fish, inherited and increased slightly in each generation? Is the explanation rather that those fishes in each generation survived and bred which happened from birth to have a slight variation in that direction, though they did not inherit the effect of the parent's effort to strain the eye? Or ought we to regard this change of structure as brought about by a few abrupt and considerable variations on the part of the young? There you have the three great schools which divide modern evolutionists: Lamarckism, Weismannism, and Mendelism (or Mutationism). All are Darwinians. No one doubts that the flat-fish was evolved from an ordinary fish--the flat-fish is an ordinary fish in its youth--or that natural selection (enemies) killed off the old and transitional types and overlooked (and so favoured) the new. It will be seen that the language used in this volume is not the particular language of any one of these schools. This is partly because I wish to leave seriously controverted questions open, and partly from a feeling of compromise, which I may explain. [*] * Of recent years another compromise has been proposed between the Lamarckians and Weismannists. It would say that the efforts of the parent and their effect on the position of the eye--in our case--are not inherited, but might be of use in sheltering an embryonic variation in the direction of a displaced eye. First, the plain issue between the Mendelians and the other two schools--whether the passage from species to species is brought about by a series of small variations during a long period or by a few large variations (or "mutations") in a short period--is open to an obvious compromise. It is quite possible that both views are correct, in different cases, and quite impossible to find the proportion of each class of cases. We shall see later that in certain instances where the conditions of preservation were good we can sometimes trace a perfectly gradual advance from species to species. Several shellfish have been traced in this way, and a sea-urchin in the chalk has been followed, quite gradually, from one end of a genus to the other. It is significant that the advance of research is multiplying these cases. There is no reason why we may not assume most of the changes of species we have yet seen to have occurred in this way. In fact, in some of the lower branches of the animal world (Radiolaria, Sponges, etc.) there is often no sharp division of species at all, but a gradual series of living varieties. On the other hand we know many instances of very considerable sudden changes. The cases quoted by Mendelists generally belong to the plant world, but instances are not unknown in the animal world. A shrimp (Artemia) was made to undergo considerable modification, by altering the proportion of salt in the water in which it was kept. Butterflies have been made to produce young quite different from their normal young by subjecting them to abnormal temperature, electric currents, and so on; and, as I said, the most remarkable effects have been produced on eggs and embryos by altering the chemical and physical conditions. Rats--I was informed by the engineer in charge of the refrigerating room on an Australian liner--very quickly became adapted to the freezing temperature by developing long hair. All that we have seen of the past changes in the environment of animals makes it probable that these larger variations often occur. I would conclude, therefore, that evolution has proceeded continuously (though by no means universally) through the ages, but there were at times periods of more acute change with correspondingly larger changes in the animal and plant worlds. In regard to the issue between the Lamarckians and Weismannists--whether changes acquired by the parent are inherited by the young--recent experiments again suggest something of a compromise. Weismann says that the body of the parent is but the case containing the germ-plasm, so that all modifications of the living parent body perish with it, and do not affect the germ, which builds the next generation. Certainly, when we reflect that the 70,000 ova in the human mother's ovary seem to have been all formed in the first year of her life, it is difficult to see how modifications of her muscles or nerves can affect them. Thus we cannot hope to learn anything, either way, by cutting off the tails of cows, and experiments of that kind. But it is acknowledged that certain diseases in the blood, which nourishes the germs, may affect them, and recent experimenters have found that they can reach and affect the germs in the body by other agencies, and so produce inherited modifications in the parent. [*] If this claim is sustained and enlarged, it may be concluded that the greater changes of environment which we find in the geological chronicle may have had a considerable influence of this kind. * See a paper read by Professor Bourne to the Zoological Section of the British Association, 1910. It must be understood that when I speak of Weismannism I do not refer to this whole theory of heredity, which, he acknowledges, has few supporters. The Lamarckian view is represented in Britain by Sir W. Turner and Professor Darwin. In other countries it has a larger proportion of distinguished supporters. On the whole subject see Professor J. A. Thomson's "Heredity" (1909), Dewar and Finn's "Making of Species" (1909--a Mendelian work), and, for essays by the leaders of each school, "Darwinism and Modern Science" (1909). The general issue, however, must remain open. The Lamarckian and Weismannist theories are rival interpretations of past events, and we shall not find it necessary to press either. When the fish comes to live on land, for instance, it develops a bony limb out of its fin. The Lamarckian says that the throwing of the weight of the body on the main stem of the fin strengthens it, as practice strengthens the boxer's arm, and the effect is inherited and increased in each generation, until at last the useless paddle of the fin dies away and the main stem has become a stout, bony column. Weismann says that the individual modification, by use in walking, is not inherited, but those young are favoured which have at birth a variation in the strength of the stem of the fin. As each of these interpretations is, and must remain, purely theoretical, we will be content to tell the facts in such cases. But these brief remarks will enable the reader to understand in what precise sense the facts we record are open to controversy. Let us return to the chronicle of the earth. We had reached the Devonian age, when large continents, with great inland seas, existed in North America, north-west Europe, and north Asia, probably connected by a continent across the North Atlantic and the Arctic region. South America and South Africa were emerging, and a continent was preparing to stretch from Brazil, through South Africa and the Antarctic, to Australia and India. The expanse of land was, with many oscillations, gaining on the water, and there was much emigration to it from the over-populated seas. When the fish went on land in the Devonian, it must have found a diet (insects, etc.) there, and the insects must have been preceded by a plant population. We have first, therefore, to consider the evolution of the plant, and see how it increases in form and number until it covers the earth with the luxuriant forests of the Carboniferous period. The plant world, we saw, starts, like the animal world, with a great kingdom of one-celled microscopic representatives, and the same principles of development, to a great extent, shape it into a large variety of forms. Armour-plating has a widespread influence among them. The graceful Diatom is a morsel of plasm enclosed in a flinty box, often with a very pretty arrangement of the pores and markings. The Desmid has a coat of cellulose, and a less graceful coat of cellulose encloses the Peridinean. Many of these minute plants develop locomotion and a degree of sensitiveness (Diatoms, Peridinea, Euglena, etc.). Some (Bacteria) adopt animal diet, and rise in power of movement and sensitiveness until it is impossible to make any satisfactory distinction between them and animals. Then the social principle enters. First we have loose associations of one-celled plants in a common bed, then closer clusters or many-celled bodies. In some cases (Volvox) the cluster, or the compound plant, is round and moves briskly in the water, closely resembling an animal. In most cases, the cells are connected in chains, and we begin to see the vague outline of the larger plant. When we had reached this stage in the development of animal life, we found great difficulty in imagining how the chief lines of the higher Invertebrates took their rise from the Archaean chaos of early many-celled forms. We have an even greater difficulty here, as plant remains are not preserved at all until the Devonian period. We can only conclude, from the later facts, that these primitive many-celled plants branched out in several different directions. One section (at a quite unknown date) adopted an organic diet, and became the Fungi; and a later co-operation, or life-partnership, between a Fungus and a one-celled Alga led to the Lichens. Others remained at the Alga-level, and grew in great thickets along the sea bottoms, no doubt rivalling or surpassing the giant sea-weeds, sometimes 400 feet long, off the American coast to-day. Other lines which start from the level of the primitive many-celled Algae develop into the Mosses (Bryophyta), Ferns (Pteridophyta), Horsetails (Equisetalia), and Club-mosses (Lycopodiales). The mosses, the lowest group, are not preserved in the rocks; from the other three classes will come the great forests of the Carboniferous period. The early record of plant-life is so poor that it is useless to speculate when the plant first left the water. We have somewhat obscure and disputed traces of ferns in the Ordovician, and, as they and the Horsetails and Club-mosses are well developed in the Devonian, we may assume that some of the sea-weeds had become adapted to life on land, and evolved into the early forms of the ferns, at least in the Cambrian period. From that time they begin to weave a mantle of sombre green over the exposed land, and to play a most important part in the economy of nature. We saw that at the beginning of the Devonian there was a considerable rise of the land both in America and Europe, but especially in Europe. A distant spectator at that time would have observed the rise of a chain of mountains in Scotland and a general emergence of land north-western Europe. A continent stretched from Ireland to Scandinavia and North Russia, while most of the rest of Europe, except large areas of Russia, France, Germany, and Turkey, was under the sea. Where we now find our Alps and Pyrenees towering up to the snow-line there were then level stretches of ocean. Even the north-western continent was scooped into great inland seas or lagoons, which stretched from Ireland to Scandinavia, and, as we saw, fostered the development of the fishes. As the Devonian period progressed the sea gained on the land, and must have restricted the growth of vegetation, but as the lake deposits now preserve the remains of the plants which grow down to their shores, or are washed into them, we are enabled to restore the complexion of the landscape. Ferns, generally of a primitive and generalised character, abound, and include the ferns such as we find in warm countries to-day. Horsetails and Club-mosses already grow into forest-trees. There are even seed-bearing ferns, which give promise of the higher plants to come, but as yet nothing approaching our flower and fruit-bearing trees has appeared. There is as yet no certain indication of the presence of Conifers. It is a sombre and monotonous vegetation, unlike any to be found in any climate to-day. We will look more closely into its nature presently. First let us see how these primitive types of plants come to form the immense forests which are recorded in our coal-beds. Dr. Russel Wallace has lately represented these forests, which have, we shall see, had a most important influence on the development of life, as somewhat mysterious in their origin. If, however, we again consult the geologist as to the changes which were taking place in the distribution of land and water, we find a quite natural explanation. Indeed, there are now distinguished geologists (e.g. Professor Chamberlin) who doubt if the Coal-forests were so exceptionally luxuriant as is generally believed. They think that the vegetation may not have been more dense than in some other ages, but that there may have been exceptionally good conditions for preserving the dead trees. We shall see that there were; but, on the whole, it seems probable that during some hundreds of thousands of years remarkably dense forests covered enormous stretches of the earth's surface, from the Arctic to the Antarctic. The Devonian period had opened with a rise of the land, but the sea eat steadily into it once more, and, with some inconsiderable oscillations of the land, regained its territory. The latter part of the Devonian and earlier part of the Carboniferous were remarkable for their great expanses of shallow water and low-lying land. Except the recent chain of hills in Scotland we know of no mountains. Professor Chamberlin calculates that 20,000,000, or 30,000,000 square miles of the present continental surface of Europe and America were covered with a shallow sea. In the deeper and clearer of these waters the earliest Carboniferous rocks, of limestone, were deposited. The "millstone grit," which succeeds the "limestone," indicates shallower water, which is being rapidly filled up with the debris of the land. In a word, all the indications suggest the early and middle Carboniferous as an age of vast swamps, of enormous stretches of land just above or below the sea-level, and changing repeatedly from one to the other. Further, the climate was at the time--we will consider the general question of climate later--moist and warm all over the earth, on account of the great proportion of sea-surface and the absence of high land (not to speak of more disputable causes). These were ideal conditions for the primitive vegetation, and it spread over the swamps with great vigour. To say that the Coal-forests were masses of Ferns, Horsetails, and Club-mosses is a lifeless and misleading expression. The Club-mosses, or Lycopodiales, were massive trees, rising sometimes to a height of 120 feet, and probably averaging about fifty feet in height and one or two feet in diameter. The largest and most abundant of them, the Sigillaria, sent up a scarred and fluted trunk to a height of seventy or a hundred feet, without a branch, and was crowned with a bunch of its long, tapering leaves. The Lepidodendron, its fellow monarch of the forest, branched at the summit, and terminated in clusters of its stiff, needle-like leaves, six' or seven inches long, like enormous exaggerations of the little cones at the ends of our Club-mosses to-day. The Horsetails, which linger in their dwarfed descendants by our streams to-day, and at their exceptional best (in a part of South America) form slender stems about thirty feet high, were then forest-trees, four to six feet in circumference and sometimes ninety feet in height. These Calamites probably rose in dense thickets from the borders of the lakes, their stumpy leaves spreading in whorls at every joint in their hollow stems. Another extinct tree, the Cordaites, rivalled the Horsetails and Club-mosses in height, and its showers of long and extraordinary leaves, six feet long and six inches in width, pointed to the higher plant world that was to come. Between these gaunt towering trunks the graceful tree-ferns spread their canopies at heights of twenty, forty, and even sixty feet from the ground, and at the base was a dense undergrowth of ferns and fern-like seed-plants. Mosses may have carpeted the moist ground, but nothing in the nature of grass or flowers had yet appeared. Imagine this dense assemblage of dull, flowerless trees pervaded by a hot, dank atmosphere, with no change of seasons, with no movement but the flying of large and primitive insects among the trees and the stirring of the ferns below by some passing giant salamander, with no song of bird and no single streak of white or red or blue drawn across the changeless sombre green, and you have some idea of the character of the forests that are compressed into our seams of coal. Imagine these forests spread from Spitzbergen to Australia and even, according to the south polar expeditions, to the Antarctic, and from the United States to Europe, to Siberia, and to China, and prolonged during some hundreds of thousands of years, and you begin to realise that the Carboniferous period prepared the land for the coming dynasties of animals. Let some vast and terrible devastation fall upon this luxuriant world, entombing the great multitude of its imperfect forms and selecting the higher types for freer life, and the earth will pass into a new age. But before we describe the animal inhabitants of these forests, the part that the forests play in the story of life, and the great cataclysm which selects the higher types from the myriads of forms which the warm womb of the earth has poured out, we must at least glance at the evolutionary position of the Carboniferous plants themselves. Do they point downward to lower forms, and upward to higher forms, as the theory of evolution requires? A close inquiry into this would lead us deep into the problems of the modern botanist, but we may borrow from him a few of the results of the great labour he has expended on the subject within the last decade. Just as the animal world is primarily divided into Invertebrates and Vertebrates, the plant world is primarily divided into a lower kingdom of spore-bearing plants (the Cryptogams) and an upper kingdom of seed-bearing plants (the Phanerogams). Again, just as the first half of the earth's story is the age of Invertebrate animals, so it is the age of Cryptogamous plants. So far evolution was always justified in the plant record. But there is a third parallel, of much greater interest. We saw that at one time the evolutionist was puzzled by the clean division of animals into Invertebrate and Vertebrate, and the sudden appearance of the backbone in the chronicle: he was just as much puzzled by the sharp division of our plants into Cryptogams and Phanerogams, and the sudden appearance of the latter on the earth during the Coal-forest period. And the issue has been a fresh and recent triumph for evolution. Plants are so well preserved in the coal that many years of microscopic study of the remains, and patient putting-together of the crushed and scattered fragments, have shown the Carboniferous plants in quite a new light. Instead of the Coal-forest being a vast assemblage of Cryptogams, upon which the higher type of the Phanerogam is going suddenly to descend from the clouds, it is, to a very great extent, a world of plants that are struggling upward, along many paths, to the higher level. The characters of the Cryptogam and Phanerogam are so mixed up in it that, although the special lines of development are difficult to trace, it is one massive testimony to the evolution of the higher from the lower. The reproductive bodies of the great Lepidodendra are sometimes more like seeds than spores, while both the wood and the leaves of the Sigillaria have features which properly belong to the Phanerogam. In another group (called the Sphenophyllales) the characters of these giant Club-mosses are blended with the characters of the giant Horsetails, and there is ground to think that the three groups have descended from an earlier common ancestor. Further, it is now believed that a large part of what were believed to be Conifers, suddenly entering from the unknown, are not Conifers at all, but Cordaites. The Cordaites is a very remarkable combination of features that are otherwise scattered among the Cryptogams, Cycads, and Conifers. On the other hand, a very large part of what the geologist had hitherto called "Ferns" have turned out to be seed-bearing plants, half Cycad and half Fern. Numbers of specimens of this interesting group--the Cycadofilices (cycad-ferns) or Pteridosperms (seed-ferns)--have been beautifully restored by our botanists. [*] They have afforded a new and very plausible ancestor for the higher trees which come on the scene toward the close of the Coal-forests, while their fern-like characters dispose botanists to think that they and the Ferns may be traced to a common ancestor. This earlier stage is lost in those primitive ages from which not a single leaf has survived in the rocks. We can only say that it is probable that the Mosses, Ferns, Lycopods, etc., arose independently from the primitive level. But the higher and more important development is now much clearer. The Coal-forest is not simply a kingdom of Cryptogams. It is a world of aspiring and mingled types. Let it be subjected to some searching test, some tremendous spell of adversity, and we shall understand the emergence of the higher types out of the luxuriant profusion and confusion of forms. * See, especially, D. H. Scott, "Studies of Fossil Botany" (2nd ed., 1908), and "The Evolution of Plants" (1910--small popular manual). CHAPTER IX. THE ANIMALS OF THE COAL-FOREST We have next to see that when this period of searching adversity comes--as it will in the next chapter--the animal world also offers a luxuriant variety of forms from which the higher types may be selected. This, it need hardly be said, is just what we find in the geological record. The fruitful, steaming, rich-laden earth now offered tens of millions of square miles of pasture to vegetal feeders; the waters, on the other hand, teemed with gigantic sharks, huge Cephalopods, large scorpion-like and lobster-like animals, and shoals of armour-plated, hard-toothed fishes. Successive swarms of vegetarians--Worms, Molluscs, etc.--followed the plant on to the land; and swarms of carnivores followed the vegetarians, and assumed strange, new forms in adaptation to land-life. The migration had probably proceeded throughout the Devonian period, especially from the calmer shores of the inland seas. By the middle of the Coal-forest period there was a very large and varied animal population on the land. Like the plants, moreover, these animals were of an intermediate and advancing nature. No bird or butterfly yet flits from tree to tree; no mammal rears its young in the shelter of the ferns. But among the swarming population are many types that show a beginning of higher organisation, and there is a rich and varied material provided for the coming selection. The monarch of the Carboniferous forest is the Amphibian. In that age of spreading swamps and "dim, watery woodlands," the stupid and sluggish Amphibian finds his golden age, and, except perhaps the scorpion, there is no other land animal competent to dispute his rule. Even the scorpion, moreover, would not find the Carboniferous Amphibian very vulnerable. We must not think of the smooth-skinned frogs and toads and innocent newts which to-day represent the fallen race of the Amphibia. They were then heavily armoured, powerfully armed, and sometimes as large as alligators or young crocodiles. It is a characteristic of advancing life that a new type of organism has its period of triumph, grows to enormous proportions, and spreads into many different types, until the next higher stage of life is reached, and it is dethroned by the new-comers. The first indication--apart from certain disputed impressions in the Devonian--of the land-vertebrate is the footprint of an Amphibian on an early Carboniferous mud-flat. Hardened by the sun, and then covered with a fresh deposit when it sank beneath the waters, it remains to-day to witness the arrival of the five-toed quadruped who was to rule the earth. As the period proceeds, remains are found in great abundance, and we see that there must have been a vast and varied population of the Amphibia on the shores of the Carboniferous lagoons and swamps. There were at least twenty genera of them living in what is now the island of Britain, and was then part of the British-Scandinavian continent. Some of them were short and stumpy creatures, a few inches long, with weak limbs and short tails, and broad, crescent-shaped heads, their bodies clothed in the fine scaly armour of their fish-ancestor (the Branchiosaurs). Some (the Aistopods) were long, snake-like creatures, with shrunken limbs and bodies drawn out until, in some cases, the backbone had 150 vertebrae. They seem to have taken to the thickets, in the growing competition, as the serpents did later, and lost the use of their limbs, which would be merely an encumbrance in winding among the roots and branches. Some (the Microsaurs) were agile little salamander-like organisms, with strong, bony frames and relatively long and useful legs; they look as if they may even have climbed the trees in pursuit of snails and insects. A fourth and more formidable sub-order, the Labyrinthodonts--which take their name from the labyrinthine folds of the enamel in their strong teeth--were commonly several feet in length. Some of them attained a length of seven or eight feet, and had plates of bone over their heads and bellies, while the jaws in their enormous heads were loaded with their strong, labyrinthine teeth. Life on land was becoming as eventful and stimulating as life in the waters. The general characteristic of these early Amphibia is that they very clearly retain the marks of their fish ancestry. All of them have tails; all of them have either scales or (like many of the fishes) plates of bone protecting the body. In some of the younger specimens the gills can still be clearly traced, but no doubt they were mainly lung-animals. We have seen how the fish obtained its lungs, and need add only that this change in the method of obtaining oxygen for the blood involved certain further changes of a very important nature. Following the fossil record, we do not observe the changes which are taking place in the soft internal organs, but we must not lose sight of them. The heart, for instance, which began as a simple muscular expansion or distension of one of the blood-vessels of some primitive worm, then doubled and became a two-chambered pump in the fish, now develops a partition in the auricle (upper chamber), so that the aerated blood is to some extent separated from the venous blood. This approach toward the warm-blooded type begins in the "mud-fish," and is connected with the development of the lungs. Corresponding changes take place in the arteries, and we shall find that this change in structure is of very great importance in the evolution of the higher types of land-life. The heart of the higher land-animals, we may add, passes through these stages in its embryonic development. Externally the chief change in the Amphibian is the appearance of definite legs. The broad paddle of the fin is now useless, and its main stem is converted into a jointed, bony limb, with a five-toed foot, spreading into a paddle, at the end. But the legs are still feeble, sprawling supports, letting the heavy body down almost to the ground. The Amphibian is an imperfect, but necessary, stage in evolution. It is an improvement on the Dipneust fish, which now begins to dwindle very considerably in the geological record, but it is itself doomed to give way speedily before one of its more advanced descendants, the Reptile. Probably the giant salamander of modern Japan affords the best suggestion of the large and primitive salamanders of the Coal-forest, while the Caecilia--snake-like Amphibia with scaly skins, which live underground in South America--may not impossibly be degenerate survivors of the curious Aistopods. Our modern tailless Amphibia, frogs and toads, appear much later in the story of the earth, but they are not without interest here on account of the remarkable capacity which they show to adapt themselves to different surroundings. There are frogs, like the tree-frog of Martinique, and others in regions where water is scarce, which never pass through the tadpole stage; or, to be quite accurate, they lose the gills and tail in the egg, as higher land-animals do. On the other hand, there is a modern Amphibian, the axolotl of Mexico, which retains the gills throughout life, and never lives on land. Dr. Gadow has shown that the lake in which it lives is so rich in food that it has little inducement to leave it for the land. Transferred to a different environment, it may pass to the land, and lose its gills. These adaptations help us to understand the rich variety of Amphibian forms that appeared in the changing conditions of the Carboniferous world. When we think of the diet of the Amphibia we are reminded of the other prominent representatives of land life at the time. Snails, spiders, and myriapods crept over the ground or along the stalks of the trees, and a vast population of insects filled the air. We find a few stray wings in the Silurian, and a large number of wings and fragments in the Devonian, but it is in the Coal-forest that we find the first great expansion of insect life, with a considerable development of myriapods, spiders, and scorpions. Food was enormously abundant, and the insect at least had no rival in the air, for neither bird nor flying reptile had yet appeared. Hence we find the same generous growth as amongst the Amphibia. Large primitive "may-flies" had wings four or five inches long; great locust-like creatures had fat bodies sometimes twenty inches in length, and soared on wings of remarkable breadth, or crawled on their six long, sprawling legs. More than a thousand species of insects, and nearly a hundred species of spiders and fifty of myriapods, are found in the remains of the Coal-forests. From the evolutionary point of view these new classes are as obscure in their origin, yet as manifestly undergoing evolution when they do fully appear, as the earlier classes we have considered. All are of a primitive and generalised character; that is to say, characters which are to-day distributed among widely different groups were then concentrated and mingled in one common ancestor, out of which the later groups will develop. All belong to the lowest orders of their class. No Hymenopters (ants, bees, and wasps) or Coleopters (beetles) are found in the Coal-forest; and it will be many millions of years before the graceful butterfly enlivens the landscapes of the earth. The early insects nearly all belong to the lower orders of the Orthopters (cockroaches, crickets, locusts, etc.) and Neuropters (dragon-flies, may-flies, etc.). A few traces of Hemipters (now mainly represented by the degenerate bugs) are found, but nine-tenths of the Carboniferous insects belong to the lowest orders of their class, the Orthopters and Neuropters. In fact, they are such primitive and generalised insects, and so frequently mingle the characteristics of the two orders, that one of the highest authorities, Scudder, groups them in a special and extinct order, the Palmodictyoptera; though this view is not now generally adopted. We shall find the higher orders of insects making their appearance in succession as the story proceeds. Thus far, then, the insects of the Coal-forest are in entire harmony with the principle of evolution, but when we try to trace their origin and earlier relations our task is beset with difficulties. It goes without saying that such delicate frames as those of the earlier insects had very little chance of being preserved in the rocks until the special conditions of the forest-age set in. We are, therefore, quite prepared to hear that the geologist cannot give us the slenderest information. He finds the wing of what he calls "the primitive bug" (Protocimex), an Hemipterous insect, in the later Ordovician, and the wing of a "primitive cockroach" (Palaeoblattina) in the Silurian. From these we can merely conclude that insects were already numerous and varied. But we have already, in similar difficulties, received assistance from the science of zoology, and we now obtain from that science a most important clue to the evolution of the insect. In South America, South Africa, and Australasia, which were at one time connected by a great southern continent, we find a little caterpillar-like creature which the zoologist regards with profound interest. It is so curious that he has been obliged to create a special class for it alone--a distinction which will be appreciated when I mention that the neighbouring class of the insects contains more than a quarter of a million living species. This valuable little animal, with its tiny head, round, elongated body, and many pairs of caterpillar-like legs, was until a few decades ago regarded as an Annelid (like the earth-worm). It has, in point of fact, the peculiar kidney-structures (nephridia) and other features of the Annelid, but a closer study discovered in it a character that separated it far from any worm-group. It was found to breathe the air by means of tracheae (little tubes running inward from the surface of the body), as the myriapods, spiders, and insects do. It was, in other words, "a kind of half-way animal between the Arthropods and the Annelids" ("Cambridge Natural History," iv, p. 5), a surviving kink in the lost chain of the ancestry of the insect. Through millions of years it has preserved a primitive frame that really belongs to the Cambrian, if not an earlier, age. It is one of the most instructive "living fossils" in the museum of nature. Peripatus, as the little animal is called, points very clearly to an Annelid ancestor of all the Tracheates (the myriapods, spiders, and insects), or all the animals that breathe by means of trachere. To understand its significance we must glance once more at an early chapter in the story of life. We saw that a vast and varied wormlike population must have filled the Archaean ocean, and that all the higher lines of animal development start from one or other point in this broad kingdom. The Annelids, in which the body consists of a long series of connected rings or segments, as in the earth-worm, are one of the highest groups of these worm-like creatures, and some branch of them developed a pair of feet (as in the caterpillar) on each segment of the body and a tough, chitinous coat. Thus arose the early Arthropods, on tough-coated, jointed, articulated animals. Some of these remained in the water, breathing by means of gills, and became the Crustacea. Some, however, migrated to the land and developed what we may almost call "lungs"--little tubes entering the body at the skin and branching internally, to bring the air into contact with the blood, the tracheae. In Peripatus we have a strange survivor of these primitive Annelid-Tracheates of many million years ago. The simple nature of its breathing apparatus suggests that the trachere were developed out of glands in the skin; just as the fish, when it came on land, probably developed lungs from its swimming bladders. The primitive Tracheates, delivered from the increasing carnivores of the waters, grew into a large and varied family, as all such new types do in favourable surroundings. From them in the course of time were evolved the three great classes of the Myriapods (millipedes and centipedes), the Arachnids (scorpions, spiders, and mites), and the Insects. I will not enter into the much-disputed and Obscure question of their nearer relationship. Some derive the Insects from the Myriapods, some the Myriapods from the Insects, and some think they evolved independently; while the rise of the spiders and scorpions is even more obscure. But how can we see any trace of an Annelid ancestor in the vastly different frames of these animals which are said to descend from it? It is not so difficult as it seems to be at first sight. In the Myriapod we still have the elongated body and successive pairs of legs. In the Arachnid the legs are reduced in number and lengthened, while the various segments of the body are fused in two distinct body-halves, the thorax and the abdomen. In the Insect we have a similar concentration of the primitive long body. The abdomen is composed of a large number (usually nine or ten) of segments which have lost their legs and fused together. In the thorax three segments are still distinctly traceable, with three pairs of legs--now long jointed limbs--as in the caterpillar ancestor; in the Carboniferous insect these three joints in the thorax are particularly clear. In the head four or five segments are fused together. Their limbs have been modified into the jaws or other mouth-appendages, and their separate nerve-centres have combined to form the large ring of nerve-matter round the gullet which represents the brain of the insect. How, then, do we account for the wings of the insect? Here we can offer nothing more than speculation, but the speculation is not without interest. It may be laid down in principle that the flying animal begins as a leaping animal. The "flying fish" may serve to suggest an early stage in the development of wings; it is a leaping fish, its extended fins merely buoying it, like the surfaces of an aeroplane, and so prolonging its leap away from its pursuer. But the great difficulty is to imagine any part of the smooth-coated primitive insect, apart from the limbs (and the wings of the insect are not developed from legs, like those of the bird), which might have even an initial usefulness in buoying the body as it leaped. It has been suggested, therefore, that the primitive insect returned to the water, as the whale and seal did in the struggle for life of a later period. The fact that the mayfly and dragon-fly spend their youth in the water is thought to confirm this. Returning to the water, the primitive insects would develop gills, like the Crustacea. After a time the stress of life in the water drove them back to the land, and the gills became useless. But the folds or scales of the tough coat, which had covered the gills, would remain as projecting planes, and are thought to have been the rudiment from which a long period of selection evolved the huge wings of the early dragon-flies and mayflies. It is generally believed that the wingless order of insects (Aptera) have not lost, but had never developed, wings, and that the insects with only one or two pairs all descend from an ancestor with three pairs. The early date of their origin, the delicacy of their structure, and the peculiar form which their larval development has generally assumed, combine to obscure the evolution of the insect, and we must be content for the present with these general indications. The vast unexplored regions of Africa, South America, and Central Australia, may yet yield further clues, and the riddle of insect-metamorphosis may some day betray the secrets which it must hold. For the moment the Carboniferous insects interest us as a rich material for the operation of a coming natural selection. On them, as on all other Carboniferous life, a great trial is about to fall. A very small proportion of them will survive that trial, and they trill be the better organised to maintain themselves and rear their young in the new earth. The remaining land-life of the Coal-forest is confined to worm-like organisms whose remains are not preserved, and land-snails which do not call for further discussion. We may, in conclusion, glance at the progress of life in the waters. Apart from the appearance of the great fishes and Crustacea, the Carboniferous period was one of great stimulation to aquatic life. Constant changes were taking place in the level and the distribution of land and water. The aspect of our coal seams to-day, alternating between thick layers of sand and mud, shows a remarkable oscillation of the land. Many recent authorities have questioned whether the trees grew on the sites where we find them to-day, and were not rather washed down into the lagoons and shallow waters from higher ground. In that case we could not too readily imagine the forest-clad region sinking below the waves, being buried under the deposits of the rivers, and then emerging, thousands of years later, to receive once more the thick mantle of sombre vegetation. Probably there was less rising and falling of the crust than earlier geologists imagined. But, as one of the most recent and most critical authorities, Professor Chamberlin, observes, the comparative purity of the coal, the fairly uniform thickness of the seams, the bed of clay representing soil at their base, the frequency with which the stumps are still found growing upright (as in the remarkable exposed Coal-forest surface in Glasgow, at the present ground-level), [*] the perfectly preserved fronds and the general mixture of flora, make it highly probable that the coal-seam generally marks the actual site of a Coal-forest, and there were considerable vicissitudes in the distribution of land and water. Great areas of land repeatedly passed beneath the waters, instead of a re-elevation of the land, however, we may suppose that the shallow water was gradually filled with silt and debris from the land, and a fresh forest grew over it. * The civic authorities of Glasgow have wisely exposed and protected this instructive piece of Coal-forest in one of their parks. I noticed, however that in the admirable printed information they supply to the public, they describe the trees as "at least several hundred thousand years old." There is no authority in the world who would grant less than ten million years since the Coal-forest period. These changes are reflected in the progress of marine life, though their influence is probably less than that of the great carnivorous monsters which now fill the waters. The heavy Arthrodirans languish and disappear. The "pavement-toothed" sharks, which at first represent three-fourths of the Elasmobranchs, dwindle in turn, and in the formidable spines which develop on them we may see evidence of the great struggle with the sharp-toothed sharks which are displacing them. The Ostracoderms die out in the presence of these competitors. The smaller fishes (generally Crossopterygii) seem to live mainly in the inland and shore waters, and advance steadily toward the modern types, but none of our modern bony fishes have yet appeared. More evident still is the effect of the new conditions upon the Crustacea. The Trilobite, once the master of the seas, slowly yields to the stronger competitors, and the latter part of the Carboniferous period sees the last genus of Trilobites finally extinguished. The Eurypterids (large scorpion-like Crustacea, several feet long) suffer equally, and are represented by a few lingering species. The stress favours the development of new and more highly organised Crustacea. One is the Limulus or "king-crab," which seems to be a descendant, or near relative, of the Trilobite, and has survived until modern times. Others announce the coming of the long-tailed Crustacea, of the lobster and shrimp type. They had primitive representatives in the earlier periods, but seem to have been overshadowed by the Trilobites and Eurypterids. As these in turn are crushed, the more highly organised Malacostraca take the lead, and primitive specimens of the shrimp and lobster make their appearance. The Echinoderms are still mainly represented by the sea-lilies. The rocks which are composed of their remains show that vast areas of the sea-floor must have been covered with groves of sea-lilies, bending on their long, flexible stalks and waving their great flower-like arms in the water to attract food. With them there is now a new experiment in the stalked Echinoderm, the Blastoid, an armless type; but it seems to have been a failure. Sea-urchins are now found in the deposits, and, although their remains are not common, we may conclude that the star-fishes were scattered over the floor of the sea. For the rest we need only observe that progress and rich diversity of forms characterise the other groups of animals. The Corals now form great reefs, and the finer Corals are gaining upon the coarser. The Foraminifers (the chalk-shelled, one-celled animals) begin to form thick rocks with their dead skeletons; the Radiolaria (the flinty-shelled microbes) are so abundant that more than twenty genera of them have been distinguished in Cornwall and Devonshire. The Brachiopods and Molluscs still abound, but the Molluscs begin to outnumber the lower type of shell-fish. In the Cephalopods we find an increasing complication of the structure of the great spiral-shelled types. Such is the life of the Carboniferous period. The world rejoices in a tropical luxuriance. Semi-tropical vegetation is found in Spitzbergen and the Antarctic, as well as in North Europe, Asia, and America, and in Australasia; corals and sea-lilies flourish at any part of the earth's surface. Warm, dank, low-lying lands, bathed by warm oceans and steeped in their vapours, are the picture suggested--as we shall see more closely--to the minds of all geologists. In those happy conditions the primitive life of the earth erupts into an abundance and variety that are fitly illustrated in the well-preserved vegetation of the forest. And when the earth has at length flooded its surface with this seething tide of life; when the air is filled with a thousand species of insects, and the forest-floor feels the heavy tread of the giant salamander and the light feet of spiders, scorpions, centipedes, and snails, and the lagoons and shores teem with animals, the Golden Age begins to close, and all the semi-tropical luxuriance is banished. A great doom is pronounced on the swarming life of the Coal-forest period, and from every hundred species of its animals and plants only two or three will survive the searching test. CHAPTER X. THE PERMIAN REVOLUTION In an earlier chapter it was stated that the story of life is a story of gradual and continuous advance, with occasional periods of more rapid progress. Hitherto it has been, in these pages, a slow and even advance from one geological age to another, one level of organisation to another. This, it is true, must not be taken too literally. Many a period of rapid change is probably contained, and blurred out of recognition, in that long chronicle of geological events. When a region sinks slowly below the waves, no matter how insensible the subsidence may be, there will often come a time of sudden and vast inundations, as the higher ridges of the coast just dip below the water-level and the lower interior is flooded. When two invading arms of the sea meet at last in the interior of the sinking continent, or when a land-barrier that has for millions of years separated two seas and their populations is obliterated, we have a similar occurrence of sudden and far-reaching change. The whole story of the earth is punctuated with small cataclysms. But we now come to a change so penetrating, so widespread, and so calamitous that, in spite of its slowness, we may venture to call it a revolution. Indeed, we may say of the remaining story of the earth that it is characterised by three such revolutions, separated by millions of years, which are very largely responsible for the appearance of higher types of life. The facts are very well illustrated by an analogy drawn from the recent and familiar history of Europe. The socio-political conditions of Europe in the eighteenth century, which were still tainted with feudalism, were changed into the socio-political conditions of the modern world, partly by a slow and continuous evolution, but much more by three revolutionary movements. First there was the great upheaval at the end of the eighteenth century, the tremors of which were felt in the life of every country in Europe. Then, although, as Freeman says, no part of Europe ever returned entirely to its former condition, there was a profound and almost universal reaction. In the 'thirties and 'forties, differing in different countries, a second revolutionary disturbance shook Europe. The reaction after this upheaval was far less severe, and the conditions were permanently changed to a great extent, but a third revolutionary movement followed in the next generation, and from that time the evolution of socio-political conditions has proceeded more evenly. The story of life on the earth since the Coal-forest period is similarly quickened by three revolutions. The first, at the close of the Carboniferous period, is the subject of this chapter. It is the most drastic and devastating of the three, but its effect, at least on the animal world, will be materially checked by a profound and protracted reaction. At the end of the Chalk period, some millions of years later, there will be a second revolution, and it will have a far more enduring and conspicuous result, though it seem less drastic at the time. Yet there will be something of a reaction after a time, and at length a third revolution will inaugurate the age of man. If it is clearly understood that instead of a century we are contemplating a period of at least ten million years, and instead of a decade of revolution we have a change spread over a hundred thousand years or more, this analogy will serve to convey a most important truth. The revolutionary agency that broke into the comparatively even chronicle of life near the close of the Carboniferous period, dethroned its older types of organisms, and ushered new types to the lordship of the earth, was cold. The reader will begin to understand why I dwelt on the aspect of the Coal-forest and its surrounding waters. There was, then, a warm, moist earth from pole to pole, not even temporarily chilled and stiffened by a few months of winter, and life spread luxuriantly in the perpetual semi-tropical summer. Then a spell of cold so severe and protracted grips the earth that glaciers glitter on the flanks of Indian and Australian hills, and fields of ice spread over what are now semitropical regions. In some degree the cold penetrates the whole earth. The rich forests shrink slowly into thin tracts of scrubby, poverty-stricken vegetation. The loss of food and the bleak and exacting conditions of the new earth annihilate thousands of species of the older organisms, and the more progressive types are moulded into fitness for the new environment. It is a colossal application of natural selection, and amongst its results are some of great moment. In various recent works one reads that earlier geologists, led astray by the nebular theory of the earth's origin, probably erred very materially in regard to the climate of primordial times, and that climate has varied less than used to be supposed. It must not be thought that, in speaking of a "Permian revolution," I am ignoring or defying this view of many distinguished geologists. I am taking careful account of it. There is no dispute, however, about the fact that the Permian age witnessed an immense carnage of Carboniferous organisms, and a very considerable modification of those organisms which survived the catastrophe, and that the great agency in this annihilation and transformation was cold. To prevent misunderstanding, nevertheless, it will be useful to explain the controversy about the climate of the earth in past ages which divides modern geologists. The root of the difference of opinion and the character of the conflicting parties have already been indicated. It is a protest of the "Planetesimalists" against the older, and still general, view of the origin of the earth. As we saw, that view implies that, as the heavier elements penetrated centreward in the condensing nebula, the gases were left as a surrounding shell of atmosphere. It was a mixed mass of gases, chiefly oxygen, hydrogen, nitrogen, and carbon-dioxide (popularly known as "carbonic acid gas"). When the water-vapour settled as ocean on the crust, the atmosphere remained a very dense mixture of oxygen, nitrogen, and carbon-dioxide--to neglect the minor gases. This heavy proportion of carbon-dioxide would cause the atmosphere to act as a glass-house over the surface of the earth, as it does still to some extent. Experiment has shown that an atmosphere containing much vapour and carbon-dioxide lets the heat-rays pass through when they are accompanied by strong light, but checks them when they are separated from the light. In other words, the primitive atmosphere would allow the heat of the sun to penetrate it, and then, as the ground absorbed the light, would retain a large proportion of the heat. Hence the semi-tropical nature of the primitive earth, the moisture, the dense clouds and constant rains that are usually ascribed to it. This condition lasted until the rocks and the forests of the Carboniferous age absorbed enormous quantities of carbon-dioxide, cleared the atmosphere, and prepared an age of chill and dryness such as we find in the Permian. But the planetesimal hypothesis has no room for this enormous percentage of carbon-dioxide in the primitive atmosphere. Hinc illoe lachrymoe: in plain English, hence the acute quarrel about primitive climate, and the close scanning of the geological chronicle for indications that the earth was not moist and warm until the end of the Carboniferous period. Once more I do not wish to enfeeble the general soundness of this account of the evolution of life by relying on any controverted theory, and we shall find it possible to avoid taking sides. I have not referred to the climate of the earth in earlier ages, except to mention that there are traces of a local "ice-age" about the middle of the Archaean and the beginning of the Cambrian. As these are many millions of years removed from each other and from the Carboniferous, it is possible that they represent earlier periods more or less corresponding to the Permian. But the early chronicle is so compressed and so imperfectly studied as yet that it is premature to discuss the point. It is, moreover, unnecessary because we know of no life on land in those remote periods, and it is only in connection with life on land that we are interested in changes of climate here. In other words, as far as the present study is concerned, we need only regard the climate of the Devonian and Carboniferous periods. As to this there is no dispute; nor, in fact, about the climate from the Cambrian to the Permian. As the new school is most brilliantly represented by Professor Chamberlin, [*] it will be enough to quote him. He says of the Cambrian that, apart from the glacial indications in its early part, "the testimony of the fossils, wherever gathered, implies nearly uniform climatic conditions... throughout all the earth wherever records of the Cambrian period are preserved" (ii, 273). Of the Ordovician he says: "All that is known of the life of this era would seem to indicate that the climate was much more uniform than now throughout the areas where the strata of the period are known" (ii, 342). In the Silurian we have "much to suggest uniformity of climate"--in fact, we have just the same evidence for it--and in the Devonian, when land-plants abound and afford better evidence, we find the same climatic equality of living things in the most different latitudes. Finally, "most of the data at hand indicate that the climate of the Lower Carboniferous was essentially uniform, and on the whole both genial and moist" (ii, 518). The "data," we may recall, are in this case enormously abundant, and indicate the climate of the earth from the Arctic regions to the Antarctic. Another recent and critical geologist, Professor Walther ("Geschichte der Erde und des Lebens," 1908), admits that the coal-vegetation shows a uniformly warm climate from Spitzbergen to Africa. Mr. Drew ("The Romance of Modern Geology," 1909) says that "nearly all over the globe the climate was the same--hot, close, moist, muggy" (p. 219). * An apology is due here in some measure. The work which I quote as of Professor Chamberlin ("Geology," 1903) is really by two authors, Professors Chamberlin and Salisbury. I merely quote Professor Chamberlin for shortness, and because the particular ideas I refer to are expounded by him in separate papers. The work is the finest manual in modern geological literature. I have used it much, in conjunction with the latest editions of Geikie, Le Conte, and Lupparent, and such recent manuals as Walther, De Launay, Suess, etc., and the geological magazines. The exception which Professor Chamberlin has in mind when he says "most of the data" is that we find deposits of salt and gypsum in the Silurian and Lower Carboniferous, and these seem to point to the evaporation of lakes in a dry climate. He admits that these indicate, at the most, local areas or periods of dryness in an overwhelmingly moist and warm earth. It is thus not disputed that the climate of the earth was, during a period of at least fifteen million years (from the Cambrian to the Carboniferous), singularly uniform, genial, and moist. During that vast period there is no evidence whatever that the earth was divided into climatic zones, or that the year was divided into seasons. To such an earth was the prolific life of the Coal-forest adapted. It is, further, not questioned that the temperature of the earth fell in the latter part of the Carboniferous age, and that the cold reached its climax in the Permian. As we turn over the pages of the geological chronicle, an extraordinary change comes over the vegetation of the earth. The great Lepidodendra gradually disappear before the close of the Permian period; the Sigillariae dwindle into a meagre and expiring race; the giant Horsetails (Calamites) shrink, and betray the adverse conditions in their thin, impoverished leaves. New, stunted, hardy trees make their appearance: the Walchia, a tree something like the low Araucarian conifers in the texture of its wood, and the Voltzia, the reputed ancestor of the cypresses. Their narrow, stunted leaves suggest to the imagination the struggle of a handful of pines on a bleak hill-side. The rich fern-population is laid waste. The seed-ferns die out, and a new and hardy type of fern, with compact leaves, the Glossopteris, spreads victoriously over the globe; from Australia it travels northward to Russia, which it reaches in the early Permian, and westward, across the southern continent, to South America. A profoundly destructive influence has fallen on the earth, and converted its rich green forests, in which the mighty Club-mosses had reared their crowns above a sea of waving ferns, into severe and poverty-stricken deserts. No botanist hesitates to say that it is the coming of a cold, dry climate that has thus changed the face of the earth. The geologist finds more direct evidence. In the Werribee Gorge in Victoria I have seen the marks which Australian geologists have discovered of the ice-age which put an end to their Coal-forests. From Tasmania to Queensland they find traces of the rivers and fields of ice which mark the close of the Carboniferous and beginning of the Permian on the southern continent. In South Africa similar indications are found from the Cape to the Transvaal. Stranger still, the geologists of India have discovered extensive areas of glaciation, belonging to this period, running down into the actual tropics. And the strangest feature of all is that the glaciers of India and Australia flowed, not from the temperate zones toward the tropics, but in the opposite direction. Two great zones of ice-covered land lay north and south of the equator. The total area was probably greater than the enormous area covered with ice in Europe and America during the familiar ice-age of the latest geological period. Thus the central idea of this chapter, the destructive inroad of a colder climate upon the genial Carboniferous world, is an accepted fact. Critical geologists may suggest that the temperature of the Coal-forest has been exaggerated, and the temperature of the Permian put too low. We are not concerned with the dispute. Whatever the exact change of temperature was, in degrees of the thermometer, it was admittedly sufficient to transform the face of the earth, and bring a mantle of ice over millions of square miles of our tropical and subtropical regions. It remains for us to inquire into the causes of this transformation. It at once occurs to us that these facts seem to confirm the prevalent idea, that the Coal-forests stripped the air of its carbon-dioxide until the earth shivered in an atmosphere thinner than that of to-day. On reflection, however, it will be seen that, if this were all that happened, we might indeed expect to find enormous ice-fields extending from the poles--which we do not find--but not glaciation in the tropics. Others may think of astronomical theories, and imagine a shrinking or clouding of the sun, or a change in the direction of the earth's axis. But these astronomical theories are now little favoured, either by astronomers or geologists. Professor Lowell bluntly calls them "astrocomic" theories. Geologists think them superfluous. There is another set of facts to be considered in connection with the Permian cold. As we have seen several times, there are periods when, either owing to the shrinking of the earth or the overloading of the sea-bottoms, or a combination of the two, the land regains its lost territory and emerges from the ocean. Mountain chains rise; new continental surfaces are exposed to the sun and rain. One of the greatest of these upheavals of the land occurs in the latter half of the Carboniferous and the Permian. In the middle of the Carboniferous, when Europe is predominantly a flat, low-lying land, largely submerged, a chain of mountains begins to rise across its central part. From Brittany to the east of Saxony the great ridge runs, and by the end of the Carboniferous it becomes a chain of lofty mountains (of which fragments remain in the Vosges, Black Forest, and Hartz mountains), dragging Central Europe high above the water, and throwing the sea back upon Russia to the north and the Mediterranean region to the south. Then the chain of the Ural Mountains begins to rise on the Russian frontier. By the beginning of the Permian Europe was higher above the water than it had ever yet been; there was only a sea in Russia and a southern sea with narrow arms trailing to the northwest. The continent of North America also had meantime emerged. The rise of the Appalachia and Ouachita mountains completes the emergence of the eastern continent, and throws the sea to the west. The Asiatic continent also is greatly enlarged, and in the southern hemisphere there is a further rise, culminating in the Permian, of the continent ("Gondwana Land") which united South America, South Africa, the Antarctic land, Australia and New Zealand, with an arm to India. In a word, we have here a physical revolution in the face of the earth. The changes were generally gradual, though they seem in some places to have been rapid and abrupt (Chamberlin); but in summary they amounted to a vast revolution in the environment of animals and plants. The low-lying, swampy, half-submerged continents reared themselves upward from the sea-level, shook the marshes and lagoons from their face, and drained the vast areas that had fostered the growth of the Coal-forests. It is calculated (Chamberlin) that the shallow seas which had covered twenty or thirty million square miles of our continental surfaces in the early Carboniferous were reduced to about five million square miles in the Permian. Geologists believe, in fact, that the area of exposed land was probably greater than it is now. This lifting and draining of so much land would of itself have a profound influence on life-conditions, and then we must take account of its indirect influence. The moisture of the earlier period was probably due in the main to the large proportion of sea-surface and the absence of high land to condense it. In both respects there is profound alteration, and the atmosphere must have become very much drier. As this vapour had been one of the atmosphere's chief elements for retaining heat at the surface of the earth, the change will involve a great lowering of temperature. The slanting of the raised land would aid this, as, in speeding the rivers, it would promote the circulation of water. Another effect would be to increase the circulation of the atmosphere. The higher and colder lands would create currents of air that had not been formed before. Lastly, the ocean currents would be profoundly modified; but the effect of this is obscure, and may be disregarded for the moment. Here, therefore, we have a massive series of causes and effects, all connected with the great emergence of the land, which throw a broad light on the change in the face of the earth. We must add the lessening of the carbon dioxide in the atmosphere. Quite apart from theories of the early atmosphere, this process must have had a great influence, and it is included by Professor Chamberlin among the causes of the world-wide change. The rocks and forests of the Carboniferous period are calculated to have absorbed two hundred times as much carbon as there is in the whole of our atmosphere to-day. Where the carbon came from we may leave open. The Planetesimalists look for its origin mainly in volcanic eruptions, but, though there was much volcanic activity in the later Carboniferous and the Permian, there is little trace of it before the Coal-forests (after the Cambrian). However that may be, there was a considerable lessening of the carbon-dioxide of the atmosphere, and this in turn had most important effects. First, the removal of so much carbon-dioxide and vapour would be a very effective reason for a general fall in the temperature of the earth. The heat received from the sun could now radiate more freely into space. Secondly, it has been shown by experiment that a richness in carbon-dioxide favours Cryptogamous plants (though it is injurious to higher plants), and a reduction of it would therefore be hurtful to the Cryptogams of the Coal-forest. One may almost put it that, in their greed, they exhausted their store. Thirdly, it meant a great purification of the atmosphere, and thus a most important preparation of the earth for higher land animals and plants. The reader will begin to think that we have sufficiently "explained" the Permian revolution. Far from it. Some of its problems are as yet insoluble. We have given no explanation at all why the ice-sheets, which we would in a general way be prepared to expect, appear in India and Australia, instead of farther north and south. Professor Chamberlin, in a profound study of the period (appendix to vol. ii, "Geology"), suggests that the new land from New Zealand to Antarctica may have diverted the currents (sea and air) up the Indian Ocean, and caused a low atmospheric pressure, much precipitation of moisture, and perpetual canopies of clouds to shield the ice from the sun. Since the outer polar regions themselves had been semi-tropical up to that time, it is very difficult to see how this will account for a freezing temperature in such latitudes as Australia and India. There does not seem to have been any ice at the Poles up to that time, or for ages afterwards, so that currents from the polar regions would be very different from what they are today. If, on the other hand, we may suppose that the rise of "Gondwana Land" (from Brazil to India) was attended by the formation of high mountains in those latitudes, we have the basis, at least, of a more plausible explanation. Professor Chamberlin rejects this supposition on the ground that the traces of ice-action are at or near the sea-level, since we find with them beds containing marine fossils. But this only shows, at the most, that the terminations of the glaciers reached the sea. We know nothing of the height of the land from which they started. For our main purpose, however, it is fortunately not necessary to clear up these mysteries. It is enough for us that the Carboniferous land rises high above the surface of the ocean over the earth generally. The shallow seas are drained off its surface; its swamps and lagoons generally disappear; its waters run in falling rivers to the ocean. The dense, moist, warm atmosphere that had so long enveloped it is changed into a thinner mantle of gas, through which, night by night, the sun-soaked ground can discharge its heat into space. Cold winds blow over it from the new mountains; probably vast regions of it are swept by icy blasts from the glaciated lands. As these conditions advance in the Permian period, the forests wither and shrink. Of the extraordinarily mixed vegetation which we found in the Coal-forests some few types are fitted to meet the severe conditions. The seed-bearing trees, the thin, needle-leafed trees, the trees with stronger texture of the wood, are slowly singled out by the deepening cold. The golden age of Cryptogams is over. The age of the Cycad and the Conifers is opening. Survivors of the old order linger in the warmer valleys, as one may see to-day tree-ferns lingering in nooks of southern regions while an Antarctic wind is whistling on the hills above them; but over the broad earth the luscious pasturage of the Coal-forest has changed into what is comparatively a cold desert. We must not, of course, imagine too abrupt a change. The earth had been by no means all swamp in the Carboniferous age. The new types were even then developing in the cooler and drier localities. But their hour has come, and there is great devastation among the lower plant population of the earth. It follows at once that there would be, on land, an equal devastation and a similar selection in the animal world. The vegetarians suffered an appalling reduction of their food; the carnivores would dwindle in the same proportion. Both types, again, would suffer from the enormous changes in their physical surroundings. Vast stretches of marsh, with teeming populations, were drained, and turned into firm, arid plains or bleak hill-sides. The area of the Amphibia, for instance, was no less reduced than their food. The cold, in turn, would exercise a most formidable selection. Before the Permian period there was not on the whole earth an animal with a warm-blooded (four-chambered) heart or a warm coat of fur or feathers; nor was there a single animal that gave any further care to the eggs it discharged, and left to the natural warmth of the earth to develop. The extermination of species in the egg alone must have been enormous. It is impossible to convey any just impression of the carnage which this Permian revolution wrought among the population of the earth. We can but estimate how many species of animals and plants were exterminated, and the reader must dimly imagine the myriads of living things that are comprised in each species. An earlier American geologist, Professor Le Conte, said that not a single Carboniferous species crossed the line of the Permian revolution. This has proved to be an exaggeration, but Professor Chamberlin seems to fall into an exaggeration on the other side when he says that 300 out of 10,000 species survived. There are only about 300 species of animals and plants known in the whole of the Permian rocks (Geikie), and most of these are new. For instance, of the enormous plant-population of the Coal-forests, comprising many thousands of species, only fifty species survived unchanged in the Permian. We may say that, as far as our knowledge goes, of every thirty species of animals and plants in the Carboniferous period, twenty-eight were blotted out of the calendar of life for ever; one survived by undergoing such modifications that it became a new species, and one was found fit to endure the new conditions for a time. We must leave it to the imagination to appreciate the total devastation of individuals entailed in this appalling application of what we call natural selection. But what higher types of life issued from the womb of nature after so long and painful a travail? The annihilation of the unfit is the seamy side, though the most real side, of natural selection. We ignore it, or extenuate it, and turn rather to consider the advances in organisation by which the survivors were enabled to outlive the great chill and impoverishment. Unfortunately, if the Permian period is an age of death, it is not an age of burials. The fossil population of its cemeteries is very scanty. Not only is the living population enormously reduced, but the areas that were accustomed to entomb and preserve organisms--the lake and shore deposits--are also greatly reduced. The frames of animals and plants now rot on the dry ground on which they live. Even in the seas, where life must have been much reduced by the general disturbance of conditions, the record is poor. Molluscs and Brachiopods and small fishes fill the list, but are of little instructiveness for us, except that they show a general advance of species. Among the Cephalopods, it is true, we find a notable arrival. On the one hand, a single small straight-shelled Cephalopod lingers for a time with the ancestral form; on the other hand, a new and formidable competitor appears among the coiled-shell Cephalopods. It is the first appearance of the famous Ammonite, but we may defer the description of it until we come to the great age of Ammonites. Of the insects and their fortunes in the great famine we have no direct knowledge; no insect remains have yet been found in Permian rocks. We shall, however, find them much advanced in the next period, and must conclude that the selection acted very effectively among their thousand Carboniferous species. The most interesting outcome of the new conditions is the rise and spread of the reptiles. No other sign of the times indicates so clearly the dawn of a new era as the appearance of these primitive, clumsy reptiles, which now begin to oust the Amphibia. The long reign of aquatic life is over; the ensign of progress passes to the land animals. The half-terrestrial, half-aquatic Amphibian deserts the water entirely (in one or more of its branches), and a new and fateful dynasty is founded. Although many of the reptiles will return to the water, when the land sinks once more, the type of the terrestrial quadruped is now fully evolved, and from its early reptilian form will emerge the lords of the air and the lords of the land, the birds and the mammals. To the uninformed it may seem that no very great advance is made when the reptile is evolved from the Amphibian. In reality the change implies a profound modification of the frame and life of the vertebrate. Partly, we may suppose, on account of the purification of the air, partly on account of the decrease in water surface, the gills are now entirely discarded. The young reptile loses them during its embryonic life--as man and all the mammals and birds do to-day--and issues from the egg a purely lung-breathing creature. A richer blood now courses through the arteries, nourishing the brain and nerves as well as the muscles. The superfluous tissue of the gill-structures is used in the improvement of the ear and mouth-parts; a process that had begun in the Amphibian. The body is raised up higher from the ground, on firmer limbs; the ribs and the shoulder and pelvic bones--the saddles by which the weight of the body is adjusted between the limbs and the backbone--are strengthened and improved. Finally, two important organs for the protection and nurture of the embryo (the amnion and the allantois) make their appearance for the first time in the reptile. In grade of organisation the reptile is really nearer to the bird than it is to the salamander. Yet these Permian reptiles are so generalised in character and so primitive in structure that they point back unmistakably to an Amphibian ancestry. The actual line of descent is obscure. When the reptiles first appear in the rocks, they are already divided into widely different groups, and must have been evolved some time before. Probably they started from some group or groups of the Amphibia in the later Carboniferous, when, as we saw, the land began to rise considerably. We have not yet recovered, and may never recover, the region where the early forms lived, and therefore cannot trace the development in detail. The fossil archives, we cannot repeat too often, are not a continuous, but a fragmentary, record of the story of life. The task of the evolutionist may be compared to the work of tracing the footsteps of a straying animal across the country. Here and there its traces will be amply registered on patches of softer ground, but for the most part they will be entirely lost on the firmer ground. So it is with the fossil record of life. Only in certain special conditions are the passing forms buried and preserved. In this case we can say only that the Permian reptiles fall into two great groups, and that one of these shows affinities to the small salamander-like Amphibia of the Coal-forest (the Microsaurs), while the other has affinities to the Labyrinthodonts. A closer examination of these early reptiles may be postponed until we come to speak of the "age of reptiles." We shall see that it is probable that an even higher type of animal, the mammal, was born in the throes of the Permian revolution. But enough has been said in vindication of the phrase which stands at the head of this chapter; and to show how the great Primary age of terrestrial life came to a close. With its new inhabitants the earth enters upon a fresh phase, and thousands of its earlier animals and plants are sealed in their primordial tombs, to await the day when man will break the seals and put flesh once more on the petrified bones. CHAPTER XI. THE MIDDLE AGES OF THE EARTH The story of the earth from the beginning of the Cambrian period to the present day was long ago divided by geologists into four great eras. The periods we have already covered--the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian--form the Primary or Palaeozoic Era, to which the earlier Archaean rocks were prefixed as a barren and less interesting introduction. The stretch of time on which we now enter, at the close of the Permian, is the Secondary or Mesozoic Era. It will be closed by a fresh upheaval of the earth and disturbance of life-conditions in the Chalk period, and followed by a Tertiary Era, in which the earth will approach its modern aspect. At its close there will be another series of upheavals, culminating in a great Ice-age, and the remaining stretch of the earth's story, in which we live, will form the Quaternary Era. In point of duration these four eras differ enormously from each other. If the first be conceived as comprising sixteen million years--a very moderate estimate--the second will be found to cover less than eight million years, the third less than three million years, and the fourth, the Age of Man, much less than one million years; while the Archaean Age was probably as long as all these put together. But the division is rather based on certain gaps, or "unconformities," in the geological record; and, although the breaches are now partially filled, we saw that they correspond to certain profound and revolutionary disturbances in the face of the earth. We retain them, therefore, as convenient and logical divisions of the biological as well as the geological chronicle, and, instead of passing from one geological period to another, we may, for the rest of the story, take these three eras as wholes, and devote a few chapters to the chief advances made by living things in each era. The Mesozoic Era will be a protracted reaction between two revolutions: a period of low-lying land, great sea-invasions, and genial climate, between two upheavals of the earth. The Tertiary Era will represent a less sharply defined depression, with genial climate and luxuriant life, between two such upheavals. The Mesozaic ("middle life") Era may very fitly be described as the Middle Ages of life on the earth. It by no means occupies a central position in the chronicle of life from the point of view of time or antiquity, just as the Middle Ages of Europe are by no means the centre of the chronicle of mankind, but its types of animals and plants are singularly transitional between the extinct ancient and the actual modern types. Life has been lifted to a higher level by the Permian revolution. Then, for some millions of years, the sterner process of selection relaxes, the warm bosom of the earth swarms again with a teeming and varied population, and a rich material is provided for the next great application of drastic selective agencies. To a poet it might seem that nature indulges each succeeding and imperfect type of living thing with a golden age before it is dismissed to make place for the higher. The Mesozoic opens in the middle of the great revolution described in the last chapter. Its first section, the Triassic period, is at first a mere continuation of the Permian. A few hundred species of animals and hardy plants are scattered over a relatively bleak and inhospitable globe. Then the land begins to sink once more. The seas spread in great arms over the revelled continents, the plant world rejoices in the increasing warmth and moisture, and the animals increase in number and variety. We pass into the Jurassic period under conditions of great geniality. Warm seas are found as far north and south as our present polar regions, and the low-lying fertile lands are covered again with rich, if less gigantic, forests, in which hordes of stupendous animals find ample nourishment. The mammal and the bird are already on the stage, but their warm coats and warm blood offer no advantage in that perennial summer, and they await in obscurity the end of the golden age of the reptiles. At the end of the Jurassic the land begins to rise once more. The warm, shallow seas drain off into the deep oceans, and the moist, swampy lands are dried. The emergence continues throughout the Cretaceous (Chalk) period. Chains of vast mountains rise slowly into the air in many parts of the earth, and a new and comparatively rapid change in the vegetation--comparable to that at the close of the Carboniferous--announces the second great revolution. The Mesozoic closes with the dismissal of the great reptiles and the plants on which they fed, and the earth is prepared for its new monarchs, the flowering plants, the birds, and the mammals. How far this repeated levelling of the land after its repeated upheavals is due to a real sinking of the crust we cannot as yet determine. The geologist of our time is disposed to restrict these mysterious rises and falls of the crust as much as possible. A much more obvious and intelligible agency has to be considered. The vast upheaval of nearly all parts of the land during the Permian period would naturally lead to a far more vigorous scouring of its surface by the rains and rivers. The higher the land, the more effectively it would be worn down. The cooler summits would condense the moisture, and the rains would sweep more energetically down the slopes of the elevated continents. There would thus be a natural process of levelling as long as the land stood out high above the water-line, but it seems probable that there was also a real sinking of the crust. Such subsidences have been known within historic times. By the end of the Triassic--a period of at least two million years--the sea had reconquered a vast proportion of the territory wrested from it in the Permian revolution. Most of Europe, west of a line drawn from the tip of Norway to the Black Sea, was under water--generally open sea in the south and centre, and inland seas or lagoons in the west. The invasion of the sea continued, and reached its climax, in the Jurassic period. The greater part of Europe was converted into an archipelago. A small continent stood out in the Baltic region. Large areas remained above the sea-level in Austria, Germany, and France. Ireland, Wales, and much of Scotland were intact, and it is probable that a land bridge still connected the west of Europe with the east of America. Europe generally was a large cluster of islands and ridges, of various sizes, in a semi-tropical sea. Southern Asia was similarly revelled, and it is probable that the seas stretched, with little interruption, from the west of Europe to the Pacific. The southern continent had deep wedges of the sea driven into it. India, New Zealand, and Australia were successively detached from it, and by the end of the Mesozoic it was much as we find it to-day. The Arctic continent (north of Europe) was flooded, and there was a great interior sea in the western part of the North American continent. This summary account of the levelling process which went on during the Triassic and Jurassic will prepare us to expect a return of warm climate and luxurious life, and this the record abundantly evinces. The enormous expansion of the sea--a great authority, Neumayr, believes that it was the greatest extension of the sea that is known in geology--and lowering of the land would of itself tend to produce this condition, and it may be that the very considerable volcanic activity, of which we find evidence in the Permian and Triassic, had discharged great volumes of carbon-dioxide into the atmosphere. Whatever the causes were, the earth has returned to paradisiacal conditions. The vast ice-fields have gone, the scanty and scrubby vegetation is replaced by luscious forests of cycads, conifers, and ferns, and warmth-loving animals penetrate to what are now the Arctic and Antarctic regions. Greenland and Spitzbergen are fragments of a continent that then bore a luxuriant growth of ferns and cycads, and housed large reptiles that could not now live thousands of miles south of it. England, and a large part of Europe, was a tranquil blue coral-ocean, the fringes of its islands girt with reefs such as we find now only three thousand miles further south, with vast shoals of Ammonites, sometimes of gigantic size, preying upon its living population or evading its monstrous sharks; while the sunlit lands were covered with graceful, palmlike cycads and early yews and pines and cypresses, and quaint forms of reptiles throve on the warm earth or in the ample swamps, or rushed on outstretched wings through the purer air. It was an evergreen world, a world, apparently, of perpetual summer. No trace is found until the next period of an alternation of summer and winter--no trees that shed their leaves annually, or show annual rings of growth in the wood--and there is little trace of zones of climate as yet. It is true that the sensitive Ammonites differ in the northern and the southern latitudes, but, as Professor Chamberlin says, it is not clear that the difference points to a diversity of climate. We may conclude that the absence of corals higher than the north of England implies a more temperate climate further north, but what Sir A. Geikie calls (with slight exaggeration) "the almost tropical aspect" of Greenland warns us to be cautious. The climate of the mid-Jurassic was very much warmer and more uniform than the climate of the earth to-day. It was an age of great vital expansion. And into this luxuriant world we shall presently find a fresh period of elevation, disturbance, and cold breaking with momentous evolutionary results. Meantime, we may take a closer look at these interesting inhabitants of the Middle Ages of the earth, before they pass away or are driven, in shrunken regiments, into the shelter of the narrowing tropics. The principal change in the aspect of the earth, as the cold, arid plains and slopes of the Triassic slowly yield the moist and warm ow-lying lands of the Jurassic, to consists in the character of the vegetation. It is wholly intermediate in its forms between that of the primitive forests and that of the modern world. The great Cryptogams of the Carboniferous world--the giant Club-mosses and their kindred--have been slain by the long period of cold and drought. Smaller Horsetails (sometimes of a great size, but generally of the modern type) and Club-mosses remain, but are not a conspicuous feature in the landscape. On the other hand, there is as yet--apart from the Conifers--no trace of the familiar trees and flowers and grasses of the later world. The vast majority of the plants are of the cycad type. These--now confined to tropical and subtropical regions--with the surviving ferns, the new Conifers, and certain trees of the ginkgo type, form the characteristic Mesozoic vegetation. A few words in the language of the modern botanist will show how this vegetation harmonises with the story of evolution. Plants are broadly divided into the lower kingdom of the Cryptogams (spore-bearing) and the upper kingdom of the Phanerogams (seed-bearing). As we saw, the Primary Era was predominantly the age of Cryptogams; the later periods witness the rise and supremacy of the Phanerogams. But these in turn are broadly divided into a less advanced group, the Gymnosperms, and a more advanced group, the Angiosperms or flowering plants. And, just as the Primary Era is the age of Cryptogams, the Secondary is the age of Gymnosperms, and the Tertiary (and present) is the age of Angiosperms. Of about 180,000 species of plants in nature to-day more than 100,000 are Angiosperms; yet up to the end of the Jurassic not a single true Angiosperm is found in the geological record. This is a broad manifestation of evolution, but it is not quite an accurate statement, and its inexactness still more strongly confirms the theory of evolution. Though the Primary Era was predominantly the age of Cryptogams, we saw that a very large number of seed-bearing plants, with very mixed characters, appeared before its close. It thus prepares the way for the cycads and conifers and ginkgoes of the Mesozoic, which we may conceive as evolved from one or other branch of the mixed Carboniferous vegetation. We next find that the Mesozoic is by no means purely an age of Gymnosperms. I do not mean merely that the Angiosperms appear in force before its close, and were probably evolved much earlier. The fact is that the Gymnosperms of the Mesozoic are often of a curiously mixed character, and well illustrate the transition to the Angiosperms, though they may not be their actual ancestors. This will be clearer if we glance in succession at the various types of plant which adorned and enriched the Jurassic world. The European or American landscape--indeed, the aspect of the earth generally, for there are no pronounced zones of climate--is still utterly different from any that we know to-day. No grass carpets the plains; none of the flowers or trees with which we are familiar, except conifers, are found in any region. Ferns grow in great abundance, and have now reached many of the forms with which we are acquainted. Thickets of bracken spread over the plains; clumps of Royal ferns and Hartstongues spring up in moister parts. The trees are conifers, cycads, and trees akin to the ginkgo, or Maidenhair Tree, of modern Japan. Cypresses, yews, firs, and araucarias (the Monkey Puzzle group) grow everywhere, though the species are more primitive than those of today. The broad, fan-like leaves and plum-like fruit of the ginkgoales, of which the temple-gardens of Japan have religiously preserved a solitary descendant, are found in the most distant regions. But the most frequent and characteristic tree of the Jurassic landscape is the cycad. The cycads--the botanist would say Cycadophyta or Cycadales, to mark them off from the cycads of modern times--formed a third of the whole Jurassic vegetation, while to-day they number only about a hundred species in 180,000, and are confined to warm latitudes. All over the earth, from the Arctic to the Antarctic, their palm-like foliage showered from the top of their generally short stems in the Jurassic. But the most interesting point about them is that a very large branch of them (the Bennettiteae) went far beyond the modern Gymnosperm in their flowers and fruit, and approached the Angiosperms. Their fructifications "rivalled the largest flowers of the present day in structure and modelling" (Scott), and possibly already gave spots of sober colour to the monotonous primitive landscape. On the other hand, they approached the ferns so much more closely than modern cycads do that it is often impossible to say whether Jurassic remains must be classed as ferns or cycads. We have here, therefore, a most interesting evolutionary group. The botanist finds even more difficulty than the zoologist in drawing up the pedigrees of his plants, but the general features of the larger groups which he finds in succession in the chronicle of the earth point very decisively to evolution. The seed-bearing ferns of the Coal-forest point upward to the later stage, and downward to a common origin with the ordinary spore-bearing ferns. Some of them are "altogether of a cycadean type" (Scott) in respect of the seed. On the other hand, the Bennettiteae of the Jurassic have the mixed characters of ferns, cycads, and flowering plants, and thus, in their turn, point downward to a lower ancestry and upward to the next great stage in plant-development. It is not suggested that the seed-ferns we know evolved into the cycads we know, and these in turn into our flowering plants. It is enough for the student of evolution to see in them so many stages in the evolution of plants up to the Angiosperm level. The gaps between the various groups are less rigid than scientific men used to think. Taller than the cycads, firmer in the structure of the wood, and destined to survive in thousands of species when the cycads would be reduced to a hundred, were the pines and yews and other conifers of the Jurassic landscape. We saw them first appearing, in the stunted Walchias and Voltzias, during the severe conditions of the Permian period. Like the birds and mammals they await the coming of a fresh period of cold to give them a decided superiority over the cycads. Botanists look for their ancestors in some form related to the Cordaites of the Coal-forest. The ginkgo trees seem to be even more closely related to the Cordaites, and evolved from an early and generalised branch of that group. The Cordaites, we may recall, more or less united in one tree the characters of the conifer (in their wood) and the cycad (in their fruit). So much for the evolutionary aspect of the Jurassic vegetation in itself. Slender as the connecting links are, it points clearly enough to a selection of higher types during the Permian revolution from the varied mass of the Carboniferous flora, and it offers in turn a singularly varied and rich group from which a fresh selection may choose yet higher types. We turn now to consider the animal population which, directly or indirectly, fed upon it, and grew with its growth. To the reptiles, the birds, and the mammals, we must devote special chapters. Here we may briefly survey the less conspicuous animals of the Mesozoic Epoch. The insects would be one of the chief classes to benefit by the renewed luxuriance of the vegetation. The Hymenopters (butterflies) have not yet appeared. They will, naturally, come with the flowers in the next great phase of organic life. But all the other orders of insects are represented, and many of our modern genera are fully evolved. The giant insects of the Coal-forest, with their mixed patriarchal features, have given place to more definite types. Swarms of dragon-flies, may-flies, termites (with wings), crickets, and cockroaches, may be gathered from the preserved remains. The beetles (Coleopters) have come on the scene in the Triassic, and prospered exceedingly. In some strata three-fourths of the insects are beetles, and as we find that many of them are wood-eaters, we are not surprised. Flies (Dipters) and ants (Hymenopters) also are found, and, although it is useless to expect to find the intermediate forms of such frail creatures, the record is of some evolutionary interest. The ants are all winged. Apparently there is as yet none of the remarkable division of labour which we find in the ants to-day, and we may trust that some later period of change may throw light on its origin. Just as the growth of the forests--for the Mesozoic vegetation has formed immense coal-beds in many parts of the world, even in Yorkshire and Scotland--explains this great development of the insects, they would in their turn supply a rich diet to the smaller land animals and flying animals of the time. We shall see this presently. Let us first glance at the advances among the inhabitants of the seas. The most important and stimulating event in the seas is the arrival of the Ammonite. One branch of the early shell-fish, it will be remembered, retained the head of its naked ancestor, and lived at the open mouth of its shell, thus giving birth to the Cephalopods. The first form was a long, straight, tapering shell, sometimes several feet long. In the course of time new forms with curved shells appeared, and began to displace the straight-shelled. Then Cephalopods with close-coiled shells, like the nautilus, came, and--such a shell being an obvious advantage--displaced the curved shells. In the Permian, we saw, a new and more advanced type of the coiled-shell animal, the Ammonite, made its appearance, and in the Triassic and Jurassic it becomes the ogre or tyrant of the invertebrate world. Sometimes an inch or less in diameter, it often attained a width of three feet or more across the shell, at the aperture of which would be a monstrous and voracious mouth. The Ammonites are not merely interesting as extinct monsters of the earth's Middle Ages, and stimulating terrors of the deep to the animals on which they fed. They have an especial interest for the evolutionist. The successive chambers which the animal adds, as it grows, to the habitation of its youth, leave the earlier chambers intact. By removing them in succession in the adult form we find an illustration of the evolution of the elaborate shell of the Jurassic Ammonite. It is an admirable testimony to the validity of the embryonic law we have often quoted--that the young animal is apt to reproduce the past stages of its ancestry--that the order of the building of the shell in the late Ammonite corresponds to the order we trace in its development in the geological chronicle. About a thousand species of Ammonites were developed in the Mesozoic, and none survived the Mesozoic. Like the Trilobites of the Primary Era, like the contemporary great reptiles on land, the Ammonites were an abortive growth, enjoying their hour of supremacy until sterner conditions bade them depart. The pretty nautilus is the only survivor to-day of the vast Mesozoic population of coiled-shell Cephalopods. A rival to the Ammonite appeared in the Triassic seas, a formidable forerunner of the cuttle-fish type of Cephalopod. The animal now boldly discards the protecting and confining shell, or spreads over the outside of it, and becomes a "shell-fish" with the shell inside. The octopus of our own time has advanced still further, and become the most powerful of the invertebrates. The Belemnite, as the Mesozoic cuttle-fish is called, attained so large a size that the internal bone, or pen (the part generally preserved), is sometimes two feet in length. The ink-bags of the Belemnite also are sometimes preserved, and we see how it could balk a pursuer by darkening the waters. It was a compensating advantage for the loss of the shell. In all the other classes of aquatic animals we find corresponding advances. In the remaining Molluscs the higher or more effective types are displacing the older. It is interesting to note that the oyster is fully developed, and has a very large kindred, in the Mesozoic seas. Among the Brachiopods the higher sloping-shoulder type displaces the square-shoulder shells. In the Crustacea the Trilobites and Eurypterids have entirely disappeared; prawns and lobsters abound, and the earliest crab makes its appearance in the English Jurassic rocks. This sudden arrival of a short-tailed Crustacean surprises us less when we learn that the crab has a long tail in its embryonic form, but the actual line of its descent is not clear. Among the Echinoderms we find that the Cystids and Blastoids have gone, and the sea-lilies reach their climax in beauty and organisation, to dwindle and almost disappear in the last part of the Mesozoic. One Jurassic sea-lily was found to have 600,000 distinct ossicles in its petrified frame. The free-moving Echinoderms are now in the ascendant, the sea-urchins being especially abundant. The Corals are, as we saw, extremely abundant, and a higher type (the Hexacoralla) is superseding the earlier and lower (Tetracoralla). Finally, we find a continuous and conspicuous advance among the fishes. At the close of the Triassic and during the Jurassic they seem to undergo profound and comparatively rapid changes. The reason will, perhaps, be apparent in the next chapter, when we describe the gigantic reptiles which feed on them in the lakes and shore-waters. A greater terror than the shark had appeared in their environment. The Ganoids and Dipneusts dwindle, and give birth to their few modern representatives. The sharks with crushing teeth diminish in number, and the sharp-toothed modern shark attains the supremacy in its class, and evolves into forms far more terrible than any that we know to-day. Skates and rays of a more or less modern type, and ancestral gar-pikes and sturgeons, enter the arena. But the most interesting new departure is the first appearance, in the Jurassic, of bony-framed fishes (Teleosts). Their superiority in organisation soon makes itself felt, and they enter upon the rapid evolution which will, by the next period, give them the first place in the fish world. Over the whole Mesozoic world, therefore, we find advance and the promise of greater advance. The Permian stress has selected the fittest types to survive from the older order; the Jurassic luxuriance is permitting a fresh and varied expansion of life, in preparation for the next great annihilation of the less fit and selection of the more fit. Life pauses before another leap. The Mesozoic earth--to apply to it the phrase which a geologist has given to its opening phase--welcomes the coming and speeds the parting guest. In the depths of the ocean a new movement is preparing, but we have yet to study the highest forms of Mesozoic life before we come to the Cretaceous disturbances. CHAPTER XII. THE AGE OF REPTILES From one point of view the advance of life on the earth seems to proceed not with the even flow of a river, but in the successive waves of an oncoming tide. It is true that we have detected a continuous advance behind all these rising and receding waves, yet their occurrence is a fact of some interest, and not a little speculation has been expended on it. When the great procession of life first emerges out of the darkness of Archaean times, it deploys into a spreading world of strange Crustaceans, and we have the Age of Trilobites. Later there is the Age of Fishes, then of Cryptogams and Amphibia, and then of Cycads and Reptiles, and there will afterwards be an Age of Birds and Mammals, and finally an Age of Man. But there is no ground for mystic speculation on this circumstance of a group of organisms fording the earth for a few million years, and then perishing or dwindling into insignificance. We shall see that a very plain and substantial process put an end to the Age of the Cycads, Ammonites, and Reptiles, and we have seen how the earlier dynasties ended. The phrase, however, the Age of Reptiles, is a fitting and true description of the greater part of the Mesozoic Era, which lies, like a fertile valley, between the Permian and the Chalk upheavals. From the bleak heights of the Permian period, or--more probably--from its more sheltered regions, in which they have lingered with the ferns and cycads, the reptiles spread out over the earth, as the summer of the Triassic period advances. In the full warmth and luxuriance of the Jurassic they become the most singular and powerful army that ever trod the earth. They include small lizard-like creatures and monsters more than a hundred feet in length. They swim like whales in the shallow seas; they shrink into the shell of the giant turtle; they rear themselves on towering hind limbs, like colossal kangaroos; they even rise into the air, and fill it with the dragons of the fairy tale. They spread over the whole earth from Australia to the Arctic circle. Then the earth seems to grow impatient of their dominance, and they shrink towards the south, and struggle in a diminished territory. The colossal monsters and the formidable dragons go the way of all primitive life, and a ragged regiment of crocodiles, turtles, and serpents in the tropics, with a swarm of smaller creatures in the fringes of the warm zone, is all that remains, by the Tertiary Era, of the world-conquering army of the Mesozoic reptiles. They had appeared, as we said, in the Permian period. Probably they had been developed during the later Carboniferous, since we find them already branched into three orders, with many sub-orders, in the Permian. The stimulating and selecting disturbances which culminated in the Permian revolution had begun in the Carboniferous. Their origin is not clear, as the intermediate forms between them and the amphibia are not found. This is not surprising, if we may suppose that some of the amphibia had, in the growing struggle, pushed inland, or that, as the land rose and the waters were drained in certain regions, they had gradually adopted a purely terrestrial life, as some of the frogs have since done. In the absence of water their frames would not be preserved and fossilised. We can, therefore, understand the gap in the record between the amphibia and the reptiles. From their structure we gather that they sprang from at least two different branches of the amphibia. Their remains fall into two great groups, which are known as the Diapsid and the Synapsid reptiles. The former seem to be more closely related to the Microsauria, or small salamander-like amphibia of the Coal-forest; the latter are nearer to the Labyrinthodonts. It is not suggested that these were their actual ancestors, but that they came from the same early amphibian root. We find both these groups, in patriarchal forms, in Europe, North America, and South Africa during the Permian period. They are usually moderate in size, but in places they seem to have found good conditions and prospered. A few years ago a Permian bed in Russia yielded a most interesting series of remains of Synapsid reptiles. Some of them were large vegetarian animals, more than twelve feet in length; others were carnivores with very powerful heads and teeth as formidable as those of the tiger. Another branch of the same order lived on the southern continent, Gondwana Land, and has left numerous remains in South Africa. We shall see that they are connected by many authorities with the origin of the mammals. [*] The other branch, the Diapsids, are represented to-day by the curiously primitive lizard of New Zealand, the tuatara (Sphenodon, or Hatteria), of which I have seen specimens, nearly two feet in length, that one did not care to approach too closely. The Diapsids are chiefly interesting, however, as the reputed ancestors of the colossal reptiles of the Jurassic age and the birds. * These Synapsid reptiles are more commonly known as Pareiasauria or Theromorpha. The purified air of the Permian world favoured the reptiles' being lung-breathers, but the cold would check their expansion for a time. The reptile, it is important to remember' usually leaves its eggs to be hatched by the natural warmth of the ground. But as the cold of the Permian yielded to a genial climate and rich vegetation in the course of the Triassic, the reptiles entered upon their memorable development. The amphibia were now definitely ousted from their position of dominance. The increase of the waters had at first favoured them, and we find more than twenty genera, and some very large individuals, of the amphibia in the Triassic. One of them, the Mastodonsaurus, had a head three feet long and two feet wide. But the spread of the reptiles checked them, and they shrank rapidly into the poor and defenceless tribe which we find them in nature to-day. To follow the prolific expansion of the reptiles in the semi-tropical conditions of the Jurassic age is a task that even the highest authorities approach with great diffidence. Science is not yet wholly agreed in the classification of the vast numbers of remains which the Mesozoic rocks have yielded, and the affinities of the various groups are very uncertain. We cannot be content, however, merely to throw on the screen, as it were, a few of the more quaint and monstrous types out of the teeming Mesozoic population, and describe their proportions and peculiarities. They fall into natural and intelligible groups or orders, and their features are closely related to the differing regions of the Jurassic world. While, therefore, we must abstain from drawing up settled genealogical trees, we may, as we review in succession the monsters of the land, the waters, and the air, glance at the most recent and substantial conjectures of scientific men as to their origin and connections. The Deinosaurs (or "terrible reptiles"), the monarchs of the land and the swamps, are the central and outstanding family of the Mesozoic reptiles. As the name implies, this group includes most of the colossal animals, such as the Diplodocus, which the illustrated magazine has made familiar to most people. Fortunately the assiduous research of American geologists and their great skill and patience in restoring the dead forms enable us to form a very fair picture of this family of medieval giants and its remarkable ramifications. [*] * See, besides the usual authorities, a valuable paper by Dr. R. S. Lull, "Dinosaurian Distribution" (1910). The Diapsid reptiles of the Permian had evolved a group with horny, parrot-like beaks, the Rhyncocephalia (or "beak-headed" reptiles), of which the tuatara of New Zealand is a lingering representative. New Zealand seems to have been cut off from the southern continent at the close of the Permian or beginning of the Triassic, and so preserved for us that very interesting relic of Permian life. From some primitive level of this group, it is generally believed, the great Deinosaurs arose. Two different orders seem to have arisen independently, or diverged rapidly from each other, in different parts of the world. One group seems to have evolved on the "lost Atlantis," the land between Western Europe and America, whence they spread westward to America, eastward over Europe, and southward to the continent which still united Africa and Australia. We find their remains in all these regions. Another stock is believed to have arisen in America. Both these groups seem to have been more or less biped, rearing themselves on large and powerful hind limbs, and (in some cases, at least) probably using their small front limbs to hold or grasp their food. The first group was carnivorous, the second herbivorous; and, as the reptiles of the first group had four or five toes on each foot, they are known as the Theropods (or "beast-footed" ), while those of the second order, which had three toes, are called the Ornithopods (or "bird-footed"). Each of them then gave birth to an order of quadrupeds. In the spreading waters and rich swamps of the later Triassic some of the Theropods were attracted to return to an amphibious life, and became the vast, sprawling, ponderous Sauropods, the giants in a world of giants. On the other hand, a branch of the vegetarian Ornithopods developed heavy armour, for defence against the carnivores, and became, under the burden of its weight, the quadrupedal and monstrous Stegosauria and Ceratopsia. Taking this instructive general view of the spread of the Deinosaurs as the best interpretation of the material we have, we may now glance at each of the orders in succession. The Theropods varied considerably in size and agility. The Compsognathus was a small, active, rabbit-like creature, standing about two feet high on its hind limbs, while the Megalosaurs stretched to a length of thirty feet, and had huge jaws armed with rows of formidable teeth. The Ceratosaur, a seventeen-foot-long reptile, had hollow bones, and we find this combination of lightness and strength in several members of the group. In many respects the group points more or less significantly toward the birds. The brain is relatively large, the neck long, and the fore limbs might be used for grasping, but had apparently ceased to serve as legs. Many of the Theropods were evidently leaping reptiles, like colossal kangaroos, twenty or more feet in length when they were erect. It is the general belief that the bird began its career as a leaping reptile, and the feathers, or expanded scales, on the front limbs helped at first to increase the leap. Some recent authorities hold, however, that the ancestor of the bird was an arboreal reptile. To the order of the Sauropods belong most of the monsters whose discovery has attracted general attention in recent years. Feeding on vegetal matter in the luscious swamps, and having their vast bulk lightened by their aquatic life, they soon attained the most formidable proportions. The admirer of the enormous skeleton of Diplodocus (which ran to eighty feet) in the British Museum must wonder how even such massive limbs could sustain the mountain of flesh that must have covered those bones. It probably did not walk so firmly as the skeleton suggests, but sprawled in the swamps or swam like a hippopotamus. But the Diplodocus is neither the largest nor heaviest of its family. The Brontosaur, though only sixty feet long, probably weighed twenty tons. We have its footprints in the rocks to-day, each impression measuring about a square yard. Generally, it is the huge thigh-bones of these monsters that have survived, and give us an idea of their size. The largest living elephant has a femur scarcely four feet long, but the femur of the Atlantosaur measures more than seventy inches, and the femur of the Brachiosaur more than eighty. Many of these Deinosaurs must have measured more than a hundred feet from the tip of the snout to the end of the tail, and stood about thirty feet high from the ground. The European Sauropods did not, apparently, reach the size of their American cousins--so early did the inferiority of Europe begin--but our Ceteosaur seems to have been about fifty feet long and ten feet in height. Its thigh-bone was sixty-four inches long and twenty-seven inches in circumference at the shaft. And in this order of reptiles, it must be remembered, the bones are solid. To complete the picture of the Sauropods, we must add that the whole class is characterised by the extraordinary smallness of the brain. The twenty-ton Brontosaur had a brain no larger than that of a new-born human infant. Quite commonly the brain of one of these enormous animals is no larger than a man's fist. It is true that, as far as the muscular and sexual labour was concerned, the brain was supplemented by a great enlargement of the spinal cord in the sacral region (at the top of the thighs). This inferior "brain" was from ten to twenty times as large as the brain in the skull. It would, however, be fully occupied with the movement of the monstrous limbs and tail, and the sex-life, and does not add in the least to the "mental" power of the Sauropods. They were stupid, sluggish, unwieldy creatures, swollen parasites upon a luxuriant vegetation, and we shall easily understand their disappearance at the end of the Mesozoic Era, when the age of brawn will yield to an age of brain. The next order of the Deinosaurs is that of the biped vegetarians, the Ornithopods, which gradually became heavily armoured and quadrupedal. The familiar Iguanodon is the chief representative of this order in Europe. Walking on its three-toed hind limbs, its head would be fourteen or fifteen feet from the ground. The front part of its jaws was toothless and covered with horn. It had, in fact, a kind of beak, and it also approached the primitive bird in the structure of its pelvis and in having five toes on its small front limbs. Some of the Ornithopods, such as the Laosaur, were small (three or four feet in height) and active, but many of the American specimens attained a great size. The Camptosaur, which was closely related to the Iguanodon in structure, was thirty feet from the snout to the end of the tail, and the head probably stood eighteen feet from the ground. One of the last great representatives of the group in America, the Trachodon, about thirty feet in length, had a most extraordinary head. It was about three and a half feet in length, and had no less than 2000 teeth lining the mouth cavity. It is conjectured that it fed on vegetation containing a large proportion of silica. In the course of the Jurassic, as we saw, a branch of these biped, bird-footed vegetarians developed heavy armour, and returned to the quadrupedal habit. We find them both in Europe and America, and must suppose that the highway across the North Atlantic still existed. The Stegosaur is one of the most singular and most familiar representatives of the group in the Jurassic. It ran to a length of thirty feet, and had a row of bony plates, from two to three feet in height, standing up vertically along the ridge of its back, while its tail was armed with formidable spikes. The Scleidosaur, an earlier and smaller (twelve-foot) specimen, also had spines and bony plates to protect it. The Polacanthus and Ankylosaur developed a most effective armour-plating over the rear. As we regard their powerful armour, we seem to see the fierce-toothed Theropods springing from the rear upon the poor-mouthed vegetarians. The carnivores selected the vegetarians, and fitted them to survive. Before the end of the Mesozoic, in fact, the Ornithopods became aggressive as well as armoured. The Triceratops had not only an enormous skull with a great ridged collar round the neck, but a sharp beak, a stout horn on the nose, and two large and sharp horns on the top of the head. We will see something later of the development of horns. The skulls of members of the Ceratops family sometimes measured eight feet from the snout to the ridge of the collar. They were, however, sluggish and stupid monsters, with smaller brains even than the Sauropods. Such, in broad outline, was the singular and powerful family of the Mesozoic Deinosaurs. Further geological research in all parts of the world will, no doubt, increase our knowledge of them, until we can fully understand them as a great family throwing out special branches to meet the different conditions of the crowded Jurassic age. Even now they afford a most interesting page in the story of evolution, and their total disappearance from the face of the earth in the next geological period will not be unintelligible. We turn from them to the remaining orders of the Jurassic reptiles. In the popular mind, perhaps, the Ichthyosaur and Plesiosaur are the typical representatives of that extinct race. The two animals, however, belong to very different branches of the reptile world, and are by no means the most formidable of the Mesozoic reptiles. Many orders of the land reptiles sent a branch into the waters in an age which, we saw, was predominantly one of water-surface. The Ichthyosauria ("fish-reptiles") and Thalattosauria ("sea-reptiles") invaded the waters at their first expansion in the later Triassic. The latter groups soon became extinct, but the former continued for some millions of years, and became remarkably adapted to marine life, like the whale at a later period. The Ichthyosaur of the Jurassic is a remarkably fish-like animal. Its long tapering frame--sometimes forty feet in length, but generally less than half that length--ends in a dip of the vertebral column and an expansion of the flesh into a strong tail-fin. The terminal bones of the limbs depart more and more from the quadruped type, until at last they are merely rows of circular bony plates embedded in the broad paddle into which the limb has been converted. The head is drawn out, sometimes to a length of five feet, and the long narrow jaws are set with two formidable rows of teeth; one specimen has about two hundred teeth. In some genera the teeth degenerate in the course of time, but this merely indicates a change of diet. One fossilised Ichthyosaur of the weaker-toothed variety has been found with the remains of two hundred Belemnites in its stomach. It is a flash of light on the fierce struggle and carnage which some recent writers have vainly striven to attenuate. The eyes, again, which may in the larger animals be fifteen inches in diameter, are protected by a circle of radiating bony plates. In fine, the discovery of young developed skeletons inside the adult frames has taught us that the Ichthgosaur had become viviparous, like the mammal. Cutting its last connection with the land, on which it originated it ceased to lay eggs, and developed the young within its body. The Ichthyosaur came of the reptile group which we have called the Diapsids. The Plesiosaur seems to belong to the Synapsid branch. In the earlier Mesozoic we find partially aquatic representatives of the line, like the Nothosaur, and in the later Plesiosaur the adaptation to a marine life is complete. The skin has lost its scales, and the front limbs are developed into powerful paddles, sometimes six feet in length. The neck is drawn out until, in some specimens, it is found to consist of seventy-six vertebrae: the longest neck in the animal world. It is now doubted, however, if the neck was very flexible, and, as the jaws were imperfectly joined, the common picture of the Plesiosaur darting its snake-like neck in all directions to seize its prey is probably wrong. It seems to have lived on small food, and been itself a rich diet to the larger carnivores. We find it in all the seas of the Mesozoic world, varying in length from six to forty feet, but it is one of the sluggish and unwieldy forms that are destined to perish in the coming crisis. The last, and perhaps the most interesting, of the doomed monsters of the Mesozoic was the Pterosaur, or "flying reptile." It is not surprising that in the fierce struggle which is reflected in the arms and armour of the great reptiles, a branch of the family escaped into the upper region. We have seen that there were leaping reptiles with hollow bones, and although the intermediate forms are missing, there is little doubt that the Pterosaur developed from one or more of these leaping Deinosaurs. As it is at first small, when it appears in the early Jurassic--it is disputed in the late Triassic--it probably came from a small and agile Deinosaur, hunted by the carnivores, which relied on its leaping powers for escape. A flapperlike broadening of the fore limbs would help to lengthen the leap, and we must suppose that this membrane increased until the animal could sail through the air, like the flying-fish, and eventually sustain its weight in the air. The wing is, of course, not a feathery frame, as in the bird, but a special skin spreading between the fore limb and the side of the body. In the bat this skin is supported by four elongated fingers of the hand, but in the Pterosaur the fifth (or fourth) finger alone--which is enormously elongated and strengthened--forms its outer frame. It is as if, in flying experiments, a man were to have a web of silk stretching from his arm and an extension of his little finger to the side of his body. From the small early specimens in the early Jurassic the flying reptiles grow larger and larger until the time of their extinction in the stresses of the Chalk upheaval. Small Pterosaurs continue throughout the period, but from these bat-like creatures we rise until we come to such dragons as the American Pteranodon, with a stretch of twenty-two feet between its extended wings and jaws about four feet long. There were long-tailed Pterosaurs (Ramphorhyncus), sometimes with a rudder-like expansion of the end of the tail, and short-tailed Pterosaurs (Pterodactyl), with compact bodies and keeled breasts, like the bird. In the earlier part of the period they all have the heavy jaws and numerous teeth of the reptile, with four or five well-developed fingers on the front limbs. In the course of time they lose the teeth--an advantage in the distribution of the weight of the body while flying--and develop horny beaks. In the gradual shaping of the breast-bone and head, also, they illustrate the evolution of the bird-form. But the birds were meantime developing from a quite different stock, and would replace the Pterosaurs at the first change in the environment. There is ground for thinking that these flying reptiles were warm-blooded like the birds. Their hollow bones seem to point to the effective breathing of a warm-blooded animal, and the great vitality they would need in flying points toward the same conclusion. Their brain, too, approached that of the bird, and was much superior to that of the other reptiles. But they had no warm coats to retain their heat, no clavicle to give strength to the wing machinery, and, especially in the later period, they became very weak in the hind limbs (and therefore weak or slow in starting their flight). The coming selection will therefore dismiss them from the scene, with the Deinosaurs and Ammonites, and retain the better organised bird as the lord of the air. There remain one or two groups of the Mesozoic reptiles which are still represented in nature. The turtle-group (Chelonia) makes its appearance in the Triassic and thrives in the Jurassic. Its members are extinct and primitive forms of the thick-shelled reptiles, but true turtles, both of marine and fresh water, abound before the close of the Mesozoic. The sea-turtles attain an enormous size. Archelon, one of the primitive types, measured about twelve feet across the shell. Another was thirteen feet long and fifteen feet from one outstretched flipper to the other. In the Chalk period they form more than a third of the reptile remains in some regions. They are extremely interesting in that they show, to some extent, the evolution of their characteristic shell. In some of the larger specimens the ribs have not yet entirely coalesced. The Crocodilians also appear in the later Triassic, abound in the Jurassic, and give way before the later types, the true Crocodiles, in the Cretaceous. They were marine animals with naked skin, a head and neck something like that of the Ichthyosaur, and paddles like those of the Plesiosaur. Their back limbs, however, were not much changed after their adaptation to life in the sea, and it is concluded that they visited the land to lay their eggs. The Teleosaur was a formidable narrow-spouted reptile, somewhat resembling the crocodiles of the Ganges in the external form of the jaws. The modern crocodiles, which replaced this ancient race of sea-crocodiles, have a great advantage over them in the fact that their nostrils open into the mouth in its lower depths. They can therefore close their teeth on their prey under water and breathe through the nose. Snakes are not found until the close of the Mesozoic, and do not figure in its characteristic reptile population. We will consider them later. But there was a large group of reptiles in the later Mesozoic seas which more or less correspond to the legendary idea of a sea-serpent. These Dolichosaurs ("long reptiles") appear at the beginning of the Chalk period, and develop into a group, the Mososaurians, which must have added considerably to the terrors of the shore-waters. Their slender scale-covered bodies were commonly twenty to thirty feet in length. The supreme representative of the order, the Mososaur, of which about forty species are known, was sometimes seventy-five feet long. It had two pairs of paddles--so that the name of sea-serpent is very imperfectly applicable--and four rows of formidable teeth on the roof of its mouth. Like the Deinosaurs and Pterosaurs, the order was doomed to be entirely extinguished after a brief supremacy in its environment. From this short and summary catalogue the reader will be able to form some conception of the living inhabitants of the Mesozoic world. It is assuredly the Age of Reptiles. Worms, snails, and spiders were, we may assume, abundant enough, and a great variety of insects flitted from tree to tree or sheltered in the fern brakes. But the characteristic life, in water and on land, was the vast and diversified family of the reptiles. In the western and the eastern continent, and along the narrowing bridge that still united them, in the northern hemisphere and the southern, and along every ridge of land that connected them, these sluggish but formidable monsters filled the stage. Every conceivable device in the way of arms and armour, brute strength and means of escape, seemed to be adopted in their development, as if they were the final and indestructible outcome of the life-principle. And within a single geological period the overwhelming majority of them, especially the larger and more formidable of them, were ruthlessly slain, leaving not a single descendant on the earth. Let us see what types of animals were thus preferred to them in the next great application of selective processes. CHAPTER XIII. THE BIRD AND THE MAMMAL In one of his finest stories, Sur La Pierre Blanche, Anatole France has imagined a group of Roman patricians discussing the future of their Empire. The Christians, who are about to rise to power on their ruin, they dismiss with amiable indifference as one of the little passing eccentricities of the religious life of their time. They have not the dimmest prevision, even as the dream of a possibility, that in a century or two the Empire of Rome will lie in the dust, and the cross will tower above all its cities from York to Jerusalem. If we might for a moment endow the animals of the Mesozoic world with AEsopian wisdom, we could imagine some such discussion taking place between a group of Deinosaur patricians. They would reflect with pride on the unshakable empire of the reptiles, and perhaps glance with disdain at two types of animals which hid in the recesses or fled to the hills of the Jurassic world. And before another era of the earth's story opened, the reptile race would be dethroned, and these hunted and despised and feeble eccentricities of Mesozoic life would become the masters of the globe. These two types of organisms were the bird and the mammal. Both existed in the Jurassic, and the mammals at least had many representatives in the Triassic. In other words, they existed, with all their higher organisation, during several million years without attaining power. The mammals remained, during at least 3,000,000 years, a small and obscure caste, immensely overshadowed by the small-brained reptiles. The birds, while making more progress, apparently, than the mammals, were far outnumbered by the flying reptiles until the last part of the Mesozoic. Then there was another momentous turn of the wheel of fate, and they emerged from their obscurity to assume the lordship of the globe. In earlier years, when some serious hesitation was felt by many to accept the new doctrine of evolution, a grave difficulty was found in the circumstance that new types--not merely new species and new genera, but new orders and even sub-classes--appeared in the geological record quite suddenly. Was it not a singular coincidence that in ALL cases the intermediate organisms between one type and another should have wholly escaped preservation? The difficulty was generally due to an imperfect acquaintance with the conditions of the problem. The fossil population of a period is only that fraction of its living population which happened to be buried in a certain kind of deposit under water of a certain depth. We shall read later of insects being preserved in resin (amber), and we have animals (and even bacteria) preserved in trees from the Coal-forests. Generally speaking, however, the earth has buried only a very minute fraction of its land-population. Moreover, only a fraction of the earth's cemeteries have yet been opened. When we further reflect that the new type of organism, when it first appears, is a small and local group, we see what the chances are of our finding specimens of it in a few scattered pages of a very fragmentary record of the earth's life. We shall see that we have discovered only about ten skeletons or fragments of skeletons of the men who lived on the earth before the Neolithic period; a stretch of some hundreds of thousands of years, recorded in the upper strata of the earth. Whatever serious difficulty there ever was in this scantiness of intermediate types is amply met by the fact that every fresh decade of search in the geological tombs brings some to light. We have seen many instances of this--the seed-bearing ferns and flower-bearing cycads, for example, found in the last decade--and will see others. But one of the most remarkable cases of the kind now claims our attention. The bird was probably evolved in the late Triassic or early Jurassic. It appears in abundance, divided into several genera, in the Chalk period. Luckily, two bird-skeletons have been found in the intermediate period, the Jurassic, and they are of the intermediate type, between the reptile and the bird, which the theory of evolution would suggest. But for the fortunate accident of these two birds being embedded in an ancient Bavarian mud-layer, which happened to be opened, for commercial purposes, in the second half of the nineteenth century, critics of evolution--if there still were any in the world of science--might be repeating to-day that the transition from the reptile to the bird was unthinkable in theory and unproven in fact. The features of the Archaeopteryx ("primitive bird") have been described so often, and such excellent pictorial restorations of its appearance may now be seen, that we may deal with it briefly. We have in it a most instructive combination of the characters of the bird and the reptile. The feathers alone, the imprint of which is excellently preserved in the fine limestone, would indicate its bird nature, but other anatomical distinctions are clearly seen in it. "There is," says Dr. Woodward, "a typical bird's 'merrythought' between the wings, and the hind leg is exactly that of a perching bird." In other words, it has the shoulder-girdle and four-toed foot, as well as the feathers, of a bird. On the other hand, it has a long tail (instead of a terminal tuft of feathers as in the bird) consisting of twenty-one vertebrae, with the feathers springing in pairs from either side; it has biconcave vertebrae, like the fishes, amphibia, and reptiles; it has teeth in its jaws; and it has three complete fingers, free and clawed, on its front limbs. As in the living Peripatus, therefore, we have here a very valuable connecting link between two very different types of organisms. It is clear that one of the smaller reptiles--the Archaeopteryx is between a pigeon and a crow in size--of the Triassic period was the ancestor of the birds. Its most conspicuous distinction was that it developed a coat of feathers. A more important difference between the bird and the reptile is that the heart of the bird is completely divided into four chambers, but, as we saw, this probably occurred also in the other flying reptiles. It may be said to be almost a condition of the greater energy of a flying animal. When the heart has four complete chambers, the carbonised blood from the tissues of the body can be conveyed direct to the lungs for purification, and the aerated blood taken direct to the tissues, without any mingling of the two. In the mud-fish and amphibian, we saw, the heart has two chambers (auricles) above, but one (ventricle) below, in which the pure and impure blood mingle. In the reptiles a partition begins to form in the lower chamber. In the turtle it is so nearly complete that the venous and the arterial blood are fairly separated; in the crocodile it is quite complete, though the arteries are imperfectly arranged. Thus the four-chambered heart of the bird and mammal is not a sudden and inexplicable development. Its advantage is enormous in a cold climate. The purer supply of blood increases the combustion in the tissues, and the animal maintains its temperature and vitality when the surrounding air falls in temperature. It ceases to be "cold-blooded." But the bird secures a further advantage, and here it outstrips the flying reptile. The naked skin of the Pterosaur would allow the heat to escape so freely when the atmosphere cooled that a great strain would be laid on its vitality. A man lessens the demand on his vitality in cold regions by wearing clothing. The bird somehow obtained clothing, in the shape of a coat of feathers, and had more vitality to spare for life-purposes in a falling temperature. The reptile is strictly limited to one region, the bird can pass from region to region as food becomes scarce. The question of the origin of the feathers can be discussed only from the speculative point of view, as they are fully developed in the Archaeopteryx, and there is no approach toward them in any other living or fossil organism. But a long discussion of the problem has convinced scientific men that the feathers are evolved from the scales of the reptile ancestor. The analogy between the shedding of the coat in a snake and the moulting of a bird is not uninstructive. In both cases the outer skin or epidermis is shedding an old growth, to be replaced by a new one. The covering or horny part of the scale and the feather are alike growths from the epidermis, and the initial stages of the growth have certain analogies. But beyond this general conviction that the feather is a development of the scale, we cannot proceed with any confidence. Nor need we linger in attempting to trace the gradual modification of the skeleton, owing to the material change in habits. The horny beak and the reduction of the toes are features we have already encountered in the reptile, and the modification of the pelvis, breast-bone, and clavicle are a natural outcome of flight. In the Chalk period we find a large number of bird remains, of about thirty different species, and in some respects they resume the story of the evolution of the bird. They are widely removed from our modern types of birds, and still have teeth in the jaws. They are of two leading types, of which the Ichthyornis and Hesperornis are the standard specimens. The Ichthyornis was a small, tern-like bird with the power of flight strongly developed, as we may gather from the frame of its wings and the keel-shaped structure of its breast-bone. Its legs and feet were small and slender, and its long, slender jaws had about twenty teeth on each side at the bottom. No modern bird has teeth; though the fact that in some modern species we find the teeth appearing in a rudimentary form is another illustration of the law that animals tend to reproduce ancestral features in their development. A more reptilian character in the Ichthyornis group is the fact that, unlike any modern bird, but like their reptile ancestors, they had biconcave vertebrae. The brain was relatively poor. We are still dealing with a type intermediate in some respects between the reptile and the modern bird. The gannets, cormorants, and pelicans are believed to descend from some branch of this group. The other group of Cretaceous birds, of the Hesperornis type, show an actual degeneration of the power of flight through adaptation to an environment in which it was not needed, as happened, later, in the kiwi of New Zealand, and is happening in the case of the barn-yard fowl. These birds had become divers. Their wings had shrunk into an abortive bone, while their powerful legs had been peculiarly fitted for diving. They stood out at right angles to the body, and seem to have developed paddles. The whole frame suggests that the bird could neither walk nor fly, but was an excellent diver and swimmer. Not infrequently as large as an ostrich (five to six feet high), with teeth set in grooves in its jaws, and the jaws themselves joined as in the snake, with a great capacity of bolting its prey, the Hesperornis would become an important element in the life of the fishes. The wing-fingers have gone, and the tail is much shortened, but the grooved teeth and loosely jointed jaws still point back to a reptilian ancestry. These are the only remains of bird-life that we find in the Mesozoic rocks. Admirably as they illustrate the evolution of the bird from the reptile, they seem to represent a relatively poor development and spread of one of the most advanced organisms of the time. It must be understood that, as we shall see, the latter part of the Chalk period does not belong to the depression, the age of genial climate, which I call the Middle Ages of the earth, but to the revolutionary period which closes it. We may say that the bird, for all its advances in organisation, remains obscure and unprosperous as long as the Age of Reptiles lasts. It awaits the next massive uplift of the land and lowering of temperature. In an earlier chapter I hinted that the bird and the mammal may have been the supreme outcomes of the series of disturbances which closed the Primary Epoch and devastated its primitive population. As far as the bird is concerned, this may be doubted on the ground that it first appears in the upper or later Jurassic, and is even then still largely reptilian in character. We must remember, however, that the elevation of the land and the cold climate lasted until the second part of the Triassic, and it is generally agreed that the bird may have been evolved in the Triassic. Its slow progress after that date is not difficult to understand. The advantage of a four-chambered heart and warm coat would be greatly reduced when the climate became warmer. The stimulus to advance would relax. The change from a coat of scales to a coat of feathers obviously means adaptation to a low temperature, and there is nothing to prevent us from locating it in the Triassic, and indeed no later known period of cold in which to place it. It is much clearer that the mammals were a product of the Permian revolution. They not only abound throughout the Jurassic, in which they are distributed in more than thirty genera, but they may be traced into the Triassic itself. Both in North America and Europe we find the teeth and fragments of the jaws of small animals which are generally recognised as mammals. We cannot, of course, from a few bones deduce that there already, in the Triassic, existed an animal with a fully developed coat of fur and an apparatus, however crude, in the breast for suckling the young. But these bones so closely resemble the bones of the lowest mammals of to-day that this seems highly probable. In the latter part of the long period of cold it seems that some reptile exchanged its scales for tufts of hair, developed a four-chambered heart, and began the practice of nourishing the young from its own blood which would give the mammals so great an ascendancy in a colder world. Nor can we complain of any lack of evidence connecting the mammal with a reptile ancestor. The earliest remains we find are of such a nature that the highest authorities are still at variance as to whether they should be classed as reptilian or mammalian. A skull and a fore limb from the Triassic of South Africa (Tritylodon and Theriodesmus) are in this predicament. It will be remembered that we divided the primitive reptiles of the Permian period into two great groups, the Diapsids and Synapsids (or Theromorphs). The former group have spread into the great reptiles of the Jurassic; the latter have remained in comparative obscurity. One branch of these Theromorph reptiles approach the mammals so closely in the formation of the teeth that they have received the name "of the Theriodonts", or "beast-toothed" reptiles. Their teeth are, like those of the mammals, divided into incisors, canines (sometimes several inches long), and molars; and the molars have in some cases developed cusps or tubercles. As the earlier remains of mammals which we find are generally teeth and jaws, the resemblance of the two groups leads to some confusion in classifying them, but from our point of view it is not unwelcome. It narrows the supposed gulf between the reptile and the mammal, and suggests very forcibly the particular branch of the reptiles to which we may look for the ancestry of the mammals. We cannot say that these Theriodont reptiles were the ancestors of the mammals. But we may conclude with some confidence that they bring us near to the point of origin, and probably had at least a common ancestor with the mammals. The distribution of the Theriodonts suggests a further idea of interest in regard to the origin of the mammals. It would be improper to press this view in the present state of our knowledge, yet it offers a plausible theory of the origin of the mammals. The Theriodonts seem to have been generally confined to the southern continent, Gondwana Land (Brazil to Australia), of which an area survives in South Africa. It is there also that we find the early disputed remains of mammals. Now we saw that, during the Permian, Gondwana Land was heavily coated with ice, and it seems natural to suppose that the severe cold which the glacial fields would give to the whole southern continent was the great agency in the evolution of the highest type of the animal world. From this southern land the new-born mammals spread northward and eastward with great rapidity. Fitted as they were to withstand the rigorous conditions which held the reptiles and amphibia in check, they seemed destined to attain at once the domination of the earth. Then, as we saw, the land was revelled once more until its surface broke into a fresh semi-tropical luxuriance, and the Deinosaurs advanced to their triumph. The mammals shrank into a meagre and insignificant population, a scattered tribe of small insect-eating animals, awaiting a fresh refrigeration of the globe. The remains of these interesting early mammals, restricted, as they generally are, to jaws and teeth and a few other bones that cannot in themselves be too confidently distinguished from those of certain reptiles, may seem insufficient to enable us to form a picture of their living forms. In this, however, we receive a singular and fortunate assistance. Some of them are found living in nature to-day, and their distinctly reptilian features would, even if no fossil remains were in existence, convince us of the evolution of the mammals. The southern continent on which we suppose the mammals to have originated had its eastern termination in Australia. New Zealand seems to have been detached early in the Mesozoic, and was never reached by the mammals. Tasmania was still part of the Australian continent. To this extreme east of the southern continent the early mammals spread, and then, during either the Jurassic or the Cretaceous, the sea completed its inroad, and severed Australia permanently from the rest of the earth. The obvious result of this was to shelter the primitive life of Australia from invasion by higher types, especially from the great carnivorous mammals which would presently develop. Australia became, in other words, a "protected area," in which primitive types of life were preserved from destruction, and were at the same time sheltered from those stimulating agencies which compelled the rest of the world to advance. "Advance Australia" is the fitting motto of the present human inhabitants of that promising country; but the standard of progress has been set up in a land which had remained during millions of years the Chinese Empire of the living world. Australia is a fragment of the Middle Ages of the earth, a province fenced round by nature at least three million years ago and preserving, amongst its many invaluable types of life, representatives of that primitive mammal population which we are seeking to understand. It is now well known that the Duckbill or Platypus (Ornithorhyncus) and the Spiny Anteater (Echidna) of Australia and Tasmania--with one representative of the latter in New Guinea, which seems to have been still connected--are semi-reptilian survivors of the first animals to suckle their young. Like the reptiles they lay tough-coated eggs and have a single outlet for the excreta, and they have a reptilian arrangement of the bones of the shoulder-girdle; like the mammals, they have a coat of hair and a four-chambered heart, and they suckle the young. Even in their mammalian features they are, as the careful research of Australian zoologists has shown, of a transitional type. They are warm-blooded, but their temperature is much lower than that of other mammals, and varies appreciably with the temperature of their surroundings. [*] Their apparatus for suckling the young is primitive. There are no teats, and the milk is forced by the mother through simple channels upon the breast, from which it is licked by the young. The Anteater develops her eggs in a pouch. They illustrate a very early stage in the development of a mammal from a reptile; and one is almost tempted to see in their timorous burrowing habits a reminiscence of the impotence of the early mammals after their premature appearance in the Triassic. * See Lucas and Le Soulf's Animals of Australia, 1909. The next level of mammal life, the highest level that it attains in Australia (apart from recent invasions), is the Marsupial. The pouched animals (kangaroo, wallaby, etc.) are the princes of pre-human life in Australia, and represent the highest point that life had reached when that continent was cut off from the rest of the world. A few words on the real significance of the pouch, from which they derive their name, will suffice to explain their position in the story of evolution. Among the reptiles the task of the mother ends, as a rule, with the laying of the egg. One or two modern reptiles hatch the eggs, or show some concern for them, but the characteristic of the reptile is to discharge its eggs upon the warm earth and trouble no further about its young. It is a reminiscence of the warm primitive earth. The bird and mammal, born of the cooling of the earth, exhibit the beginning of that link between mother and offspring which will prove so important an element in the higher and later life of the globe. The bird assists the development of the eggs with the heat of her own body, and feeds the young. The mammal develops the young within the body, and then feeds them at the breast. But there is a gradual advance in this process. The Duckbill lays its eggs just like the reptile, but provides a warm nest for them at the bottom of its burrow. The Anteater develops a temporary pouch in its body, when it lays an egg, and hatches the egg in it. The Marsupial retains the egg in its womb until the young is advanced in development, then transfers the young to the pouch, and forces milk into its mouth from its breasts. The real reason for this is that the Marsupial falls far short of the higher mammals in the structure of the womb, and cannot fully develop its young therein. It has no placenta, or arrangement by which the blood-vessels of the mother are brought into connection with the blood-vessels of the foetus, in order to supply it with food until it is fully developed. The Marsupial, in fact, only rises above the reptile in hatching the egg within its own body, and then suckling the young at the breast. These primitive mammals help us to reconstruct the mammal life of the Mesozoic Epoch. The bones that we have are variously described in geological manuals as the remains of Monotremes, Marsupials, and Insectivores. Many of them, if not most, were no doubt insect-eating animals, but there is no ground for supposing that what are technically known as Insectivores (moles and shrews) existed in the Mesozoic. On the other hand, the lower jaw of the Marsupial is characterised by a peculiar hooklike process, and this is commonly found in Mesozoic jaws. This circumstance, and the witness of Australia, permit us, perhaps, to regard the Jurassic mammals as predominantly marsupial. It is more difficult to identify Monotreme remains, but the fact that Monotremes have survived to this day in Australia, and the resemblance of some of the Mesozoic teeth to those found for a time in the young Duckbill justify us in assuming that a part of the Mesozoic mammals correspond to the modern Monotremes. Not single specimen of any higher, or placental, mammal has yet been found in the whole Mesozoic Era. We must, however, beware of simply transferring to the Mesozoic world the kinds of Monotremes and Marsupials which we know in nature to-day. In some of the excellent "restorations" of Mesozoic life which are found in recent illustrated literature the early mammal is represented with an external appearance like that of the Duckbill. This is an error, as the Duckbill has been greatly modified in its extremities and mouth-parts by its aquatic and burrowing habits. As we have no complete skeletons of these early mammals we must abstain from picturing their external appearance. It is enough that the living Monotreme and Marsupial so finely illustrate the transition from a reptilian to a mammalian form. There may have been types more primitive than the Duckbill, and others between the Duckbill and the Marsupial. It seems clear, at least, that two main branches, the Monotremes and Marsupials, arose from the primitive mammalian root. Whether either of these became in turn the parent of the higher mammals we will inquire later. We must first consider the fresh series of terrestrial disturbances which, like some gigantic sieve, weeded out the grosser types of organisms, and cleared the earth for a rapid and remarkable expansion of these primitive birds and mammals. We have attended only to a few prominent characters in tracing the line of evolution, but it will be understood that an advance in many organs of the body is implied in these changes. In the lower mammals the diaphragm, or complete partition between the organs of the breast and those of the abdomen, is developed. It is not a sudden and mysterious growth, and its development in the embryo to-day corresponds to the suggestion of its development which the zoologist gathers from the animal series. The ear also is now fully developed. How far the fish has a sense of hearing is not yet fully determined, but the amphibian certainly has an organ for the perception of waves of sound. Parts of the discarded gill-arches are gradually transformed into the three bones of the mammal's internal ear; just as other parts are converted into mouth cartilages, and as--it is believed--one of the gill clefts is converted into the Eustachian tube. In the Monotreme and Marsupial the ear-hole begins to be covered with a shell of cartilage; we have the beginning of the external ear. The jaws, which are first developed in the fish, now articulate more perfectly with the skull. Fat-glands appear in the skin, and it is probably from a group of these that the milk-glands are developed. The origin of the hairs is somewhat obscure. They are not thought to be, like the bird's feathers, modifications of the reptile's scales, but to have been evolved from other structures in the skin, possibly under the protection of the scales. My purpose is, however, rather to indicate the general causes of the onward advance of life than to study organs in detail--a vast subject--or construct pedigrees. We therefore pass on to consider the next great stride that is taken by the advancing life of the earth. Millions of years of genial climate and rich vegetation have filled the earth with a prolific and enormously varied population. Over this population the hand of natural selection is outstretched, as it were, and we are about to witness another gigantic removal of older types of life and promotion of those which contain the germs of further advance. As we have already explained, natural selection is by no means inactive during these intervening periods of warmth. We have seen the ammonites and reptiles, and even the birds and mammals, evolve into hundreds of species during the Jurassic period. The constant evolution of more effective types of carnivores and their spread into new regions, the continuous changes in the distribution of land and water, the struggle for food in a growing population, and a dozen other causes, are ever at work. But the great and comprehensive changes in the face of the earth which close the eras of the geologist seem to give a deeper and quicker stimulus to its population and result in periods of especially rapid evolution. Such a change now closes the Mesozoic Era, and inaugurates the age of flowering plants, of birds, and of mammals. CHAPTER XIV. IN THE DAYS OF THE CHALK In accordance with the view of the later story of the earth which was expressed on an earlier page, we now come to the second of the three great revolutions which have quickened the pulse of life on the earth. Many men of science resent the use of the word revolution, and it is not without some danger. It was once thought that the earth was really shaken at times by vast and sudden cataclysms, which destroyed its entire living population, so that new kingdoms of plants and animals had to be created. But we have interpreted the word revolution in a very different sense. The series of changes and disturbances to which we give the name extended over a period of hundreds of thousands of years, and they were themselves, in some sense, the creators of new types of organisms. Yet they are periods that stand out peculiarly in the comparatively even chronicle of the earth. The Permian period transformed the face of the earth; it lifted the low-lying land into a massive relief, drew mantles of ice over millions of miles of its surface, set volcanoes belching out fire and fumes in many parts, stripped it of its great forests, and slew the overwhelming majority of its animals. On the scale of geological time it may be called a revolution. It must be confessed that the series of disturbances which close the Secondary and inaugurate the Tertiary Era cannot so conveniently be summed up in a single formula. They begin long before the end of the Mesozoic, and they continue far into the Tertiary, with intervals of ease and tranquillity. There seems to have been no culminating point in the series when the uplifted earth shivered in a mantle of ice and snow. Yet I propose to retain for this period--beginning early in the Cretaceous (Chalk) period and extending into the Tertiary--the name of the Cretaceous Revolution. I drew a fanciful parallel between the three revolutions which have quickened the earth since the sluggish days of the Coal-forest and the three revolutionary movements which have changed the life of modern Europe. It will be remembered that, whereas the first of these European revolutions was a sharp and massive upheaval, the second consisted in a more scattered and irregular series of disturbances, spread over the fourth and fifth decades of the nineteenth century; but they amounted, in effect, to a revolution. So it is with the Cretaceous Revolution. In effect it corresponds very closely to the Permian Revolution. On the physical side it includes a very considerable rise of the land over the greater part of the globe, and the formation of lofty chains of mountains; on the botanical side it means the reduction of the rich Mesozoic flora to a relatively insignificant population, and the appearance and triumphant spread of the flowering plants, on the zoological side it witnesses the complete extinction of the Ammonites, Deinosaurs, and Pterosaurs, an immense reduction of the reptile world generally, and a victorious expansion of the higher insects, birds, and mammals; on the climatic side it provides the first definite evidence of cold zones of the earth and cold seasons of the year, and seems to represent a long, if irregular, period of comparative cold. Except, to some extent, the last of these points, there is no difference of opinion, and therefore, from the evolutionary point of view, the Cretaceous period merits the title of a revolution. All these things were done before the Tertiary period opened. Let us first consider the fundamental and physical aspect of this revolution, the upheaval of the land. It began about the close of the Jurassic period. Western and Central Europe emerged considerably from the warm Jurassic sea, which lay on it and had converted it into an archipelago. In North-western America also there was an emergence of large areas of land, and the Sierra and Cascade ranges of mountains were formed about the same time. For reasons which will appear later we must note carefully this rise of land at the very beginning of the Cretaceous period. However, the sea recovered its lost territory, or compensation for it, and the middle of the Cretaceous period witnessed a very considerable extension of the waters over America, Europe, and southern Asia. The thick familiar beds of chalk, which stretch irregularly from Ireland to the Crimea, and from the south of Sweden to the south of France, plainly tell of an overlying sea. As is well known, the chalk consists mainly of the shells or outer frames of minute one-celled creatures (Thalamophores) which float in the ocean, and form a deep ooze at its bottom with their discarded skeletons. What depth this ocean must have been is disputed, and hardly concerns us. It is clear that it must have taken an enormous period for microscopic shells to form the thick masses of chalk which cover so much of southern and eastern England. On the lowest estimates the Cretaceous period, which includes the deposit of other strata besides chalk, lasted about three million years. And as people like to have some idea of the time since these things happened, I may add that, on the lowest estimate (which most geologists would at least double), it is about three million years since the last stretches of the chalk-ocean disappeared from the surface of Europe. But while our chalk cliffs conjure up a vision of England lying deep--at least twenty or thirty fathoms deep--below a warm ocean, in which gigantic Ammonites and Belemnites and sharks ply their deadly trade, they also remind us of the last phase of the remarkable life of the earth's Middle Ages. In the latter part of the Cretaceous the land rises. The chalk ocean of Europe is gradually reduced to a series of inland seas, separated by masses and ridges of land, and finally to a series of lakes of brackish water. The masses of the Pyrenees and Alps begin to rise; though it will not be until a much later date that they reach anything like their present elevation. In America the change is even greater. A vast ridge rises along the whole western front of the continent, lifting and draining it, from Alaska to Cape Horn. It is the beginning of the Rocky Mountains and the Andes. Even during the Cretaceous period there had been rich forests of Mesozoic vegetation covering about a hundred thousand square miles in the Rocky Mountains region. Europe and America now begin to show their modern contours. It is important to notice that this great uprise of the land and the series of disturbances it entails differ from those which we summed up in the phrase Permian Revolution. The differences may help us to understand some of the changes in the living population. The chief difference is that the disturbances are more local, and not nearly simultaneous. There is a considerable emergence of land at the end of the Jurassic, then a fresh expansion of the sea, then a great rise of mountains at the end of the Cretaceous, and so on. We shall find our great mountain-masses (the Pyrenees, Alps, Himalaya, etc.) rising at intervals throughout the whole of the Tertiary Era. However, it suffices for the moment to observe that in the latter part of the Mesozoic and early part of the Tertiary there were considerable upheavals of the land in various regions, and that the Mesozoic Era closed with a very much larger proportion of dry land, and a much higher relief of the land, than there had been during the Jurassic period. The series of disturbances was, says Professor Chamberlin, "greater than any that had occurred since the close of the Palaeozoic." From the previous effect of the Permian upheaval, and from the fact that the living population is now similarly annihilated or reduced, we should at once expect to find a fresh change in the climate of the earth. Here, however, our procedure is not so easy. In the Permian age we had solid proof in the shape of vast glaciated regions. It is claimed by continental geologists that certain early Tertiary beds in Bavaria actually prove a similar, but smaller, glaciation in Europe, but this is disputed. Other beds may yet be found, but we saw that there was not a general upheaval, as there had been in the Permian, and it is quite possible that there were few or no ice-fields. We do not, in fact, know the causes of the Permian icefields. We are thrown upon the plant and animal remains, and seem to be in some danger of inferring a cold climate from the organic remains, and then explaining the new types of organisms by the cold climate. This, of course, we shall not do. The difficulty is made greater by the extreme disinclination of many recent geologists, and some recent botanists who have too easily followed the geologists, to admit a plain climatic interpretation of the facts. Let us first see what the facts are. In the latter part of the Jurassic we find three different zones of Ammonites: one in the latitude of the Mediterranean, one in the latitude of Central Europe, and one further north. Most geologists conclude that these differences indicate zones of climate (not hitherto indicated), but it cannot be proved, and we may leave the matter open. At the same time the warm-loving corals disappear from Europe, with occasional advances. It is said that they are driven out by the disturbance of the waters, and, although this would hardly explain why they did not spread again in the tranquil chalk-ocean, we may again leave the point open. In the early part of the Cretaceous, however, the Angiosperms (flowering plants) suddenly break into the chronicle of the earth, and spread with great rapidity. They appear abruptly in the east of the North American continent, in the region of Virginia and Maryland. They are small in stature and primitive in structure. Some are of generalised forms that are now unknown; some have leaves approaching those of the oak, willow, elm, maple, and walnut; some may be definitely described as fig, sassafras, aralia, myrica, etc. Eastern America, it may be recalled, is much higher than western until the close of the Cretaceous period. The Angiosperms do not spread much westward; they appear next in Greenland, and, before the middle of the Cretaceous, in Portugal. They have travelled over the North Atlantic continent, or what remains of it. The process seems very rapid as we write it, but it must be remembered that the first half of the Cretaceous period means a million or a million and a half years. The cycads, and even the conifers, shrink before the higher type of tree. The landscape, in Europe and America, begins to wear a modern aspect. Long before the end of the Cretaceous most of the modern genera of Angiosperm trees have developed. To the fig and sassafras are now added the birch, beech, oak, poplar, walnut, willow, ivy, mulberry, holly, laurel, myrtle, maple, oleander, magnolia, plane, bread-fruit, and sweet-gum. Most of the American trees of to-day are known. The sequoias (the giant Californian trees) still represent the conifers in great abundance, with the eucalyptus and other plants that are now found only much further south. The ginkgoes struggle on for a time. The cycads dwindle enormously. Of 700 specimens in one early Cretaceous deposit only 96 are Angiosperms; of 460 species in a later deposit about 400 are Angiosperms. They oust the cycads in Europe and America, as the cycads and conifers had ousted the Cryptogams. The change in the face of the earth would be remarkable. Instead of the groves of palm-like cycads, with their large and flower-like fructifications, above which the pines and firs and cypresses reared their sombre forms, there were now forests of delicate-leaved maples, beeches, and oaks, bearing nutritious fruit for the coming race of animals. Grasses also and palms begin in the Cretaceous; though the grasses would at first be coarse and isolated tufts. Even flowers, of the lily family (apparently), are still detected in the crushed and petrified remains. We will give some consideration later to the evolution of the Angiosperms. For the moment it is chiefly important to notice a feature of them to which the botanist pays less attention. In his technical view the Angiosperm is distinguished by the structure of its reproductive apparatus, its flowers, and some recent botanists wonder whether the key to this expansion of the flowering plants may not be found in a development of the insect world and of its relation to vegetation. In point of fact, we have no geological indication of any great development of the insects until the Tertiary Era, when we shall find them deploying into a vast army and producing their highest types. In any case, such a view leaves wholly unexplained the feature of the Angiosperms which chiefly concerns us. This is that most of them shed the whole of their leaves periodically, as the winter approaches. No such trees had yet been known on the earth. All trees hitherto had been evergreen, and we need a specific and adequate explanation why the earth is now covered, in the northern region, with forests of trees which show naked boughs and branches during a part of the year. The majority of palaeontologists conclude at once, and quite confidently, from this rise and spread of the deciduous trees, that a winter season has at length set in on the earth, and that this new type of vegetation appears in response to an appreciable lowering of the climate. The facts, however, are somewhat complex, and we must proceed with caution. It would seem that any general lowering of the temperature of the earth ought to betray itself first in Greenland, but the flora of Greenland remains far "warmer," so to say, than the flora of Central Europe is to-day. Even toward the close of the Cretaceous its plants are much the same as those of America or of Central Europe. Its fossil remains of that time include forty species of ferns, as well as cycads, ginkgoes, figs, bamboos, and magnolias. Sir A. Geikie ventures to say that it must then have enjoyed a climate like that of the Cape or of Australia to-day. Professor Chamberlin finds its flora like that of "warm temperate" regions, and says that plants which then flourished in latitude 72 degrees are not now found above latitude 30 degrees. There are, however, various reasons to believe that it is unsafe to draw deductions from the climate of Greenland. There is, it is true, some exaggeration in the statement that its climate was equivalent to that of Central Europe. The palms which flourished in Central Europe did not reach Greenland, and there are differences in the northern Molluscs and Echinoderms which--like the absence of corals above the north of England--point to a diversity of temperature. But we have no right to expect that there would be the same difference in temperature between Greenland and Central Europe as we find to-day. If the warm current which is now diverted to Europe across the Atlantic--the Gulf Stream--had then continued up the coast of America, and flowed along the coast of the land that united America and Europe, the climatic conditions would be very different from what they are. There is a more substantial reason. We saw that during the Mesozoic the Arctic continent was very largely submerged, and, while Europe and America rise again at the end of the Cretaceous, we find no rise of the land further north. A difference of elevation would, in such a world, make a great difference in temperature and moisture. Let us examine the animal record, however, before we come to any conclusion. The chronicle of the later Cretaceous is a story of devastation. The reduction of the cyeads is insignificant beside the reduction or annihilation of the great animals of the Mesozoic world. The skeletons of the Deinosaurs become fewer and fewer as we ascend the upper Cretaceous strata. In the uppermost layer (Laramie) we find traces of a last curious expansion--the group of horned reptiles, of the Triceratops type, which we described as the last of the great reptiles. The Ichthyosaurs and Plesiosaurs vanish from the waters. The "sea-serpents" (Mososaurs) pass away without a survivor. The flying dragons, large and small, become entirely extinct. Only crocodiles, lizards, turtle, and snakes cross the threshold of the Tertiary Era. In one single region of America (Puerco beds) some of the great reptiles seem to be making a last stand against the advancing enemy in the dawn of the Tertiary Era, but the exact date of the beds is disputed, and in any case their fight is soon over. Something has slain the most formidable race that the earth had yet known, in spite of its marvellous adaptation to different environments in its innumerable branches. We turn to the seas, and find an equal carnage among some of its most advanced inhabitants. The great cuttlefish-like Belemnites and the whole race of the Ammonites, large and small, are banished from the earth. The fall of the Ammonites is particularly interesting, and has inspired much more or less fantastic speculation. The shells begin to assume such strange forms that observers speak occasionally of the "convulsions" or "death-contortions" of the expiring race. Some of the coiled shells take on a spiral form, like that of a snail's shell. Some uncoil the shell, and seem to be returning toward the primitive type. A rich eccentricity of frills and ornamentation is found more or less throughout the whole race. But every device--if we may so regard these changes--is useless, and the devastating agency of the Cretaceous, whatever it was, removes the Ammonites and Belemnites from the scene. The Mollusc world, like the world of plants and of reptiles, approaches its modern aspect. In the fish world, too, there is an effective selection in the course of the Cretaceous. All the fishes of modern times, except the large family of the sharks, rays, skates, and dog-fishes (Elasmobranchs), the sturgeon and chimaera, the mud-fishes, and a very few other types, are Teleosts, or bony-framed fishes--the others having cartilaginous frames. None of the Teleosts had appeared until the end of the Jurassic. They now, like the flowering plants on land, not only herald the new age, but rapidly oust the other fishes, except the unconquerable shark. They gradually approach the familiar types of Teleosts, so that we may say that before the end of the Cretaceous the waters swarmed with primitive and patriarchal cod, salmon, herring, perch, pike, bream, eels, and other fishes. Some of them grew to an enormous size. The Portheus, an American pike, seems to have been about eight feet long; and the activity of an eight-foot pike may be left to the angler's imagination. All, however, are, as evolution demands, of a generalised and unfamiliar type: the material out of which our fishes will be evolved. Of the insects we have very little trace in the Cretaceous. We shall find them developing with great richness in the following period, but, imperfect as the record is, we may venture to say that they were checked in the Cretaceous. There were good conditions for preserving them, but few are preserved. And of the other groups of invertebrates we need only say that they show a steady advance toward modern types. The sea-lily fills the rocks no longer; the sea-urchin is very abundant. The Molluscs gain on the more lowly organised Brachiopods. To complete the picture we must add that higher types probably arose in the later Cretaceous which do not appear in the records. This is particularly true of the birds and mammals. We find them spreading so early in the Tertiary that we must put back the beginning of the expansion to the Cretaceous. As yet, however, the only mammal remains we find are such jaws and teeth of primitive mammals as we have already described. The birds we described (after the Archaeopteryx) also belong to the Cretaceous, and they form another of the doomed races. Probably the modern birds were already developing among the new vegetation on the higher ground. These are the facts of Cretaceous life, as far as the record has yielded them, and it remains for us to understand them. Clearly there has been a great selective process analogous to, if not equal to, the winnowing process at the end of the Palaeozoic. As there has been a similar, if less considerable, upheaval of the land, we are at once tempted to think that the great selective agency was a lowering of the temperature. When we further find that the most important change in the animal world is the destruction of the cold-blooded reptiles, which have no concern for the young, and the luxuriant spread of the warm-blooded animals, which do care for their young, the idea is greatly confirmed. When we add that the powerful Molluscs which are slain, while the humbler Molluscs survive, are those which--to judge from the nautilus and octopus--love warm seas, the impression is further confirmed. And when we finally reflect that the most distinctive phenomenon of the period is the rapid spread of deciduous trees, it would seem that there is only one possible interpretation of the Cretaceous Revolution. This interpretation--that cold was the selecting agency--is a familiar idea in geological literature, but, as I said, there are recent writers who profess reserve in regard to it, and it is proper to glance at, or at least look for, the alternatives. Before doing so let us be quite clear that here we have nothing to do with theories of the origin of the earth. The Permian cold--which, however, is universally admitted--is more or less entangled in that controversy; the Cretaceous cold has no connection with it. Whatever excess of carbon-dioxide there may have been in the early atmosphere was cleared by the Coal-forests. We must set aside all these theories in explaining the present facts. It is also useful to note that the fact that there have been great changes in the climate of the earth in past time is beyond dispute. There is no denying the fact that the climate of the earth was warm from the Arctic to the Antarctic in the Devonian and Carboniferous periods: that it fell considerably in the Permian: that it again became at least "warm temperate" (Chamberlin) from the Arctic to the Antarctic in the Jurassic, and again in the Eocene: that some millions of square miles of Europe and North America were covered with ice and snow in the Pleistocene, so that the reindeer wandered where palms had previously flourished and the vine flourishes to-day; and that the pronounced zones of climate which we find today have no counterpart in any earlier age. In view of these great and admitted fluctuations of the earth's temperature one does not see any reason for hesitating to admit a fall of temperature in the Cretaceous, if the facts point to it. On the other hand, the alternative suggestions are not very convincing. We have noticed one of these suggestions in connection with the origin of the Angiosperms. It hints that this may be related to developments of the insect world. Most probably the development of the characteristic flowers of the Angiosperms is connected with an increasing relation to insects, but what we want to understand especially is the deciduous character of their leaves. Many of the Angiosperms are evergreen, so that it cannot be said that the one change entailed the other. In fact, a careful study of the leaves preserved in the rocks seems to show the deciduous Angiosperms gaining on the evergreens at the end of the Cretaceous. The most natural, it not the only, interpretation of this is that the temperature is falling. Deciduous trees shed their leaves so as to check their transpiration when a season comes on in which they cannot absorb the normal amount of moisture. This may occur either at the on-coming of a hot, dry season or of a cold season (in which the roots absorb less). Everything suggests that the deciduous tree evolved to meet an increase of cold, not of heat. Another suggestion is that animals and plants were not "climatically differentiated" until the Cretaceous period; that is to say, that they were adapted to all climates before that time, and then began to be sensitive to differences of climate, and live in different latitudes. But how and why they should suddenly become differentiated in this way is so mysterious that one prefers to think that, as the animal remains also suggest, there were no appreciable zones of climate until the Cretaceous. The magnolia, for instance, flourished in Greenland in the early Tertiary, and has to live very far south of it to-day. It is much simpler to assume that Greenland changed--as a vast amount of evidence indicates--than that the magnolia changed. Finally, to explain the disappearance of the Mesozoic reptiles without a fall in temperature, it is suggested that they were exterminated by the advancing mammals. It is assumed that the spreading world of the Angiospermous plants somewhere met the spread of the advancing mammals, and opened out a rich new granary to them. This led to so powerful a development of the mammals that they succeeded in overthrowing the reptiles. There are several serious difficulties in the way of this theory. The first and most decisive is that the great reptiles have practically disappeared before the mammals come on the scene. Only in one series of beds (Puerco) in America, representing an early period of the Tertiary Era, do we find any association of their remains; and even there it is not clear that they were contemporary. Over the earth generally the geological record shows the great reptiles dying from some invisible scourge long before any mammal capable of doing them any harm appears; even if we suppose that the mammal mainly attacked the eggs and the young. We may very well believe that more powerful mammals than the primitive Mesozoic specimens were already developed in some part of the earth--say, Africa--and that the rise of the land gave them a bridge across the Mediterranean to Europe. Probably this happened; but the important point is that the reptiles were already almost extinct. The difficulty is even greater when we reflect that it is precisely the most powerful reptiles (Deinosaurs) and least accessible reptiles (Pterosaurs, Ichthyosaurs, etc.) which disappear, while the smaller land and water reptiles survive and retreat southward--where the mammals are just as numerous. That assuredly is not the effect of an invasion of carnivores, even if we could overlook the absence of such carnivores from the record until after the extinction of the reptiles in most places. I have entered somewhat fully into this point, partly because of its great interest, but partly lest it be thought that I am merely reproducing a tradition of geological literature without giving due attention to the criticisms of recent writers. The plain and common interpretation of the Cretaceous revolution--that a fall in temperature was its chief devastating agency--is the only one that brings harmony into all the facts. The one comprehensive enemy of that vast reptile population was cold. It was fatal to the adult because he had a three-chambered heart and no warm coat; it was fatal to the Mesozoic vegetation on which, directly or indirectly, he fed; it was fatal to his eggs and young because the mother did not brood over the one or care for the other. It was fatal to the Pterosaurs, even if they were warm-blooded, because they had no warm coats and did not (presumably) hatch their eggs; and it was equally fatal to the viviparous Ichthyosaurs. It is the one common fate that could slay all classes. When we find that the surviving reptiles retreat southward, only lingering in Europe during the renewed warmth of the Eocene and Miocene periods, this interpretation is sufficiently confirmed. And when we recollect that these things coincide with the extinction of the Ammonites and Belemnites, and the driving of their descendants further south, as well as the rise and triumph of deciduous trees, it is difficult to see any ground for hesitating. But we need not, and must not, imagine a period of cold as severe, prolonged, and general as that of the Permian period. The warmth of the Jurassic period is generally attributed to the low relief of the land, and the very large proportion of water-surface. The effect of this would be to increase the moisture in the atmosphere. Whether this was assisted by any abnormal proportion of carbon-dioxide, as in the Carboniferous, we cannot confidently say. Professor Chamberlin observes that, since the absorbing rock-surface was greatly reduced in the Jurassic, the carbon-dioxide would tend to accumulate in its atmosphere, and help to explain the high temperature. But the great spread of vegetation and the rise of land in the later Jurassic and the Cretaceous would reduce this density of the atmosphere, and help to lower the temperature. It is clear that the cold would at first be local. In fact, it must be carefully realised that, when we speak of the Jurassic period as a time of uniform warmth, we mean uniform at the same altitude. Everybody knows the effect of rising from the warm, moist sea-level to the top of even a small inland elevation. There would be such cooler regions throughout the Jurassic, and we saw that there were considerable upheavals of land towards its close. To these elevated lands we may look for the development of the Angiosperms, the birds, and the mammals. When the more massive rise of land came at the end of the Cretaceous, the temperature would fall over larger areas, and connecting ridges would be established between one area and another. The Mesozoic plants and animals would succumb to this advancing cold. What precise degree of cold was necessary to kill the reptiles and Cephalopods, yet allow certain of the more delicate flowering plants to live, is yet to be determined. The vast majority of the new plants, with their winter sleep, would thrive in the cooler air, and, occupying the ground of the retreating cycads and ginkgoes would prepare a rich harvest for the coming birds and mammals. CHAPTER XV. THE TERTIARY ERA We have already traversed nearly nine-tenths of the story of terrestrial life, without counting the long and obscure Archaean period, and still find ourselves in a strange and unfamiliar earth. With the close of the Chalk period, however, we take a long stride in the direction of the modern world. The Tertiary Era will, in the main, prove a fresh period of genial warmth and fertile low-lying regions. During its course our deciduous trees and grasses will mingle with the palms and pines over the land, our flowers will begin to brighten the landscape, and the forms of our familiar birds and mammals, even the form of man, will be discernible in the crowds of animals. At its close another mighty period of selection will clear the stage for its modern actors. A curious reflection is prompted in connection with this division of the earth's story into periods of relative prosperity and quiescence, separated by periods of disturbance. There was--on the most modest estimate--a stretch of some fifteen million years between the Cambrian and the Permian upheavals. On the same chronological scale the interval between the Permian and Cretaceous revolutions was only about seven million years, and the Tertiary Era will comprise only about three million years. One wonders if the Fourth (Quaternary) Era in which we live will be similarly shortened. Further, whereas the earth returned after each of the earlier upheavals to what seems to have been its primitive condition of equable and warm climate, it has now entirely departed from that condition, and exhibits very different zones of climate and a succession of seasons in the year. One wonders what the climate of the earth will become long before the expiration of those ten million years which are usually assigned as the minimum period during which the globe will remain habitable. It is premature to glance at the future, when we are still some millions of years from the present, but it will be useful to look more closely at the facts which inspire this reflection. From what we have seen, and shall further see, it is clear that, in spite of all the recent controversy about climate among our geologists, there has undeniably been a progressive refrigeration of the globe. Every geologist, indeed, admits "oscillations of climate," as Professor Chamberlin puts it. But amidst all these oscillations we trace a steady lowering of the temperature. Unless we put a strained and somewhat arbitrary interpretation on the facts of the geological record, earlier ages knew nothing of our division of the year into pronounced seasons and of the globe into very different climatic zones. It might plausibly be suggested that we are still living in the last days of the Ice-Age, and that the earth may be slowly returning to a warmer condition. Shackleton, it might be observed, found that there has been a considerable shrinkage of the south polar ice within the period of exploration. But we shall find that a difference of climate, as compared with earlier ages, was already evident in the middle of the Tertiary Era, and it is far more noticeable to-day. We do not know the causes of this climatic evolution--the point will be considered more closely in connection with the last Ice-Age--but we see that it throws a flood of light on the evolution of organisms. It is one of the chief incarnations of natural selection. Changes in the distribution of land and water and in the nature of the land-surface, the coming of powerful carnivores, and other agencies which we have seen, have had their share in the onward impulsion of life, but the most drastic agency seems to have been the supervention of cold. The higher types of both animals and plants appear plainly in response to a lowering of temperature. This is the chief advantage of studying the story of evolution in strict connection with the geological record. We shall find that the record will continue to throw light on our path to the end, but, as we are now about to approach the most important era of evolution, and as we have now seen so much of the concrete story of evolution, it will be interesting to examine briefly some other ways of conceiving that story. We need not return to the consideration of the leading schools of evolution, as described in a former chapter. Nothing that we have seen will enable us to choose between the Lamarckian and the Weismannist hypothesis; and I doubt if anything we are yet to see will prove more decisive. The dispute is somewhat academic, and not vital to a conception of evolution. We shall, for instance, presently follow the evolution of the horse, and see four of its toes shrink and disappear, while the fifth toe is enormously strengthened. In the facts themselves there is nothing whatever to decide whether this evolution took place on the lines suggested by Weismann, or on the lines suggested by Lamarck and accepted by Darwin. It will be enough for us merely to establish the fact that the one-toed horse is an evolved descendant of a primitive five-toed mammal, through the adaptation of its foot to running on firm ground, its teeth and neck to feeding on grasses, and so on. On the other hand, the facts we have already seen seem to justify the attitude of compromise I adopted in regard to the Mutationist theory. It would be an advantage in many ways if we could believe that new species arose by sudden and large variations (mutations) of the young from the parental type. In the case of many organs and habits it is extremely difficult to see how a gradual development, by a slow accentuation of small variations, is possible. When we further find that experimenters on living species can bring about such mutations, and when we reflect that there must have been acute disturbances in the surroundings of animals and plants sometimes, we are disposed to think that many a new species may have arisen in this way. On the other hand, while the palaeontological record can never prove that a species arose by mutations, it does sometimes show that species arise by very gradual modification. The Chalk period, which we have just traversed, affords a very clear instance. One of our chief investigators of the English Chalk, Dr. Rowe, paid particular attention to the sea-urchins it contains, as they serve well to identify different levels of chalk. He discovered, not merely that they vary from level to level, but that in at least one genus (Micraster) he could trace the organism very gradually passing from one species to another, without any leap or abruptness. It is certainly significant that we find such cases as this precisely where the conditions of preservation are exceptionally good. We must conclude that species arise, probably, both by mutations and small variations, and that it is impossible to say which class of species has been the more numerous. There remain one or two conceptions of evolution which we have not hitherto noticed, as it was advisable to see the facts first. One of these is the view--chiefly represented in this country by Professor Henslow--that natural selection has had no part in the creation of species; that the only two factors are the environment and the organism which responds to its changes. This is true enough in the sense that, as we saw, natural selection is not an action of nature on the "fit," but on the unfit or less fit. But this does not in the least lessen the importance of natural selection. If there were not in nature this body of destructive agencies, to which we apply the name natural selection, there would be little--we cannot say no--evolution. But the rising carnivores, the falls of temperature, etc., that we have studied, have had so real, if indirect, an influence on the development of life that we need not dwell on this. Another school, or several schools, while admitting the action of natural selection, maintain that earlier evolutionists have made nature much too red in tooth and claw. Dr. Russel Wallace from one motive, and Prince Krapotkin from another, have insisted that the triumphs of war have been exaggerated, and the triumphs of peace, or of social co-operation, far too little appreciated. It will be found that such writers usually base their theory on life as we find it in nature to-day, where the social principle is highly developed in many groups of animals. This is most misleading, since social co-operation among animals, as an instrument of progress, is (geologically speaking) quite a recent phenomenon. Nearly every group of animals in which it is found belongs, to put it moderately, to the last tenth of the story of life, and in some of the chief instances the animals have only gradually developed social life. [*] The first nine-tenths of the chronicle of evolution contain no indication of social life, except--curiously enough--in such groups as the Sponges, Corals, and Bryozoa, which are amongst the least progressive in nature. We have seen plainly that during the overwhelmingly greater part of the story of life the predominant agencies of evolution were struggle against adverse conditions and devouring carnivores; and we shall find them the predominant agencies throughout the Tertiary Era. * Thus the social nature of man is sometimes quoted as one of the chief causes of his development. It is true that it has much to do with his later development, but we shall see that the statement that man was from the start a social being is not at all warranted by the facts. On the other hand, it may be pointed out that the ants and termites had appeared in the Mesozoic. We shall see some evidence that the remarkable division of labour which now characterises their life did not begin until a much later period, so that we have no evidence of social life in the early stages. Yet we must protest against the exaggerated estimate of the conscious pain which so many read into these millions of years of struggle. Probably there was no consciousness at all during the greater part of the time. The wriggling of the worm on which you have accidentally trodden is no proof whatever that you have caused conscious pain. The nervous system of an animal has been so evolved as to respond with great disturbance of its tissue to any dangerous or injurious assault. It is the selection of a certain means of self-preservation. But at what level of life the animal becomes conscious of this disturbance, and "feels pain," it is very difficult to determine. The subject is too vast to be opened here. In a special investigation of it. [*] I concluded that there is no proof of the presence of any degree of consciousness in the invertebrate world even in the higher insects; that there is probably only a dull, blurred, imperfect consciousness below the level of the higher mammals and birds; and that even the consciousness of an ape is something very different from what educated Europeans, on the ground of their own experience, call consciousness. It is too often forgotten that pain is in proportion to consciousness. We must beware of such fallacies as transferring our experience of pain to a Mesozoic reptile, with an ounce or two of cerebrum to twenty tons of muscle and bone. * "The Evolution of Mind" (Black), 1911. One other view of evolution, which we find in some recent and reputable works (such as Professor Geddes and Thomson's "Evolution," 1911), calls for consideration. In the ordinary Darwinian view the variations of the young from their parents are indefinite, and spread in all directions. They may continue to occur for ages without any of them proving an advantage to their possessors. Then the environment may change, and a certain variation may prove an advantage, and be continuously and increasingly selected. Thus these indefinite variations may be so controlled by the environment during millions of years that the fish at last becomes an elephant or a man. The alternative view, urged by a few writers, is that the variations were "definitely directed." The phrase seems merely to complicate the story of evolution with a fresh and superfluous mystery. The nature and precise action of this "definite direction" within the organism are quite unintelligible, and the facts seem explainable just as well--or not less imperfectly--without as with this mystic agency. Radiolaria, Sponges, Corals, Sharks, Mudfishes, Duckbills, etc., do not change (except within the limits of their family) during millions of years, because they keep to an environment to which they are fitted. On the other hand, certain fishes, reptiles, etc., remain in a changing environment, and they must change with it. The process has its obscurities, but we make them darker, it seems to me, with these semi-metaphysical phrases. It has seemed advisable to take this further glance at the general principles and current theories of evolution before we extend our own procedure into the Tertiary Era. The highest types of animals and plants are now about to appear on the stage of the earth; the theatre itself is about to take on a modern complexion. The Middle Ages are over; the new age is breaking upon the planet. We will, as before, first survey the Tertiary Era as a whole, with the momentous changes it introduces, and then examine, in separate chapters, the more important phases of its life. It opens, like the preceding and the following era, with "the area of land large and its relief pronounced." This is the outcome of the Cretaceous revolution. Southern Europe and Southern Asia have risen, and shaken the last masses of the Chalk ocean from their faces; the whole western fringe of America has similarly emerged from the sea that had flooded it. In many parts, as in England (at that time a part of the Continent), there is so great a gap between the latest Cretaceous and the earliest Tertiary strata that these newly elevated lands must evidently have stood out of the waters for a prolonged period. On their cooler plains the tragedy of the extinction of the great reptiles comes to an end. The cyeads and ginkgoes have shrunk into thin survivors of the luxuriant Mesozoic groves. The oak and beech and other deciduous trees spread slowly over the successive lands, amid the glare and thunder of the numerous volcanoes which the disturbance of the crust has brought into play. New forms of birds fly from tree to tree, or linger by the waters; and strange patriarchal types of mammals begin to move among the bones of the stricken reptiles. But the seas and the rains and rivers are acting with renewed vigour on the elevated lands, and the Eocene period closes in a fresh age of levelling. Let us put the work of a million years or so in a sentence. The southern sea, which has been confined almost to the limits of our Mediterranean by the Cretaceous upheaval, gradually enlarges once more. It floods the north-west of Africa almost as far as the equator; it covers most of Italy, Turkey, Austria, and Southern Russia; it spreads over Asia Minor, Persia, and Southern Asia, until it joins the Pacific; and it sends a long arm across the Franco-British region, and up the great valley which is now the German Ocean. From earlier chapters we now expect to find a warmer climate, and the record gives abundant proof of it. To this period belongs the "London Clay," in whose thick and--to the unskilled eye--insignificant bed the geologist reads the remarkable story of what London was two or three million years ago. It tells us that a sea, some 500 or 600 feet deep, then lay over that part of England, and fragments of the life of the period are preserved in its deposit. The sea lay at the mouth of a sub-tropical river on whose banks grew palms, figs, ginkgoes, eucalyptuses, almonds, and magnolias, with the more familiar oaks and pines and laurels. Sword-fishes and monstrous sharks lived in the sea. Large turtles and crocodiles and enormous "sea-serpents" lingered in this last spell of warmth that Central Europe would experience. A primitive whale appeared in the seas, and strange large tapir-like mammals--remote ancestors of our horses and more familiar beasts--wandered heavily on the land. Gigantic primitive birds, sometimes ten feet high, waded by the shore. Deposits of the period at Bournemouth and in the Isle of Wight tell the same story of a land that bore figs, vines, palms, araucarias, and aralias, and waters that sheltered turtles and crocodiles. The Parisian region presented the same features. In fact, one of the most characteristic traces of the southern sea which then stretched from England to Africa in the south and India in the east indicates a warm climate. It will be remembered that the Cretaceous ocean over Southern Europe had swarmed with the animalcules whose dead skeletons largely compose our chalk-beds. In the new southern ocean another branch of these Thalamophores, the Nummulites, spreads with such portentous abundance that its shells--sometimes alone, generally with other material--make beds of solid limestone several thousand feet in thickness. The pyramids are built of this nummulitic limestone. The one-celled animal in its shell is, however, no longer a microscopic grain. It sometimes forms wonderful shells, an inch or more in diameter, in which as many as a thousand chambers succeed each other, in spiral order, from the centre. The beds containing it are found from the Pyrenees to Japan. That this vast warm ocean, stretching southward over a large part of what is now the Sahara, should give a semitropical aspect even to Central Europe and Asia is not surprising. But this genial climate was still very general over the earth. Evergreens which now need the warmth of Italy or the Riviera then flourished in Lapland and Spitzbergen. The flora of Greenland--a flora that includes magnolias, figs, and bamboos--shows us that its temperature in the Eocene period must have been about 30 degrees higher than it is to-day. [*] The temperature of the cool Tyrol of modern Europe is calculated to have then been between 74 and 81 degrees F. Palms, cactuses, aloes, gum-trees, cinnamon trees, etc., flourished in the latitude of Northern France. The forests that covered parts of Switzerland which are now buried in snow during a great part of the year were like the forests one finds in parts of India and Australia to-day. The climate of North America, and of the land which still connected it with Europe, was correspondingly genial. * The great authority on Arctic geology, Heer, who makes this calculation, puts this flora in the Miocene. It is now usually considered that these warmer plants belong to the earlier part of the Tertiary era. This indulgent period (the Oligocene, or later part of the Eocene), scattering a rich and nutritious vegetation with great profusion over the land, led to a notable expansion of animal life. Insects, birds, and mammals spread into vast and varied groups in every land. Had any of the great Mesozoic reptiles survived, the warmer age might have enabled them to dispute the sovereignty of the advancing mammals. But nothing more formidable than the turtle, the snake, and the crocodile (confined to the waters) had crossed the threshold of the Tertiary Era, and the mammals and birds had the full advantage of the new golden age. The fruits of the new trees, the grasses which now covered the plains, and the insects which multiplied with the flowers afforded a magnificent diet. The herbivorous mammals became a populous world, branching into numerous different types according to their different environments. The horse, the elephant, the camel, the pig, the deer, the rhinoceros gradually emerge out of the chaos of evolving forms. Behind them, hastening the course of their evolution, improving their speed, arms, and armour, is the inevitable carnivore. He, too, in the abundance of food, grows into a vast population, and branches out toward familiar types. We will devote a chapter presently to this remarkable phase of the story of evolution. But the golden age closes, as all golden ages had done before it, and for the same reason. The land begins to rise, and cast the warm shallow seas from its face. The expansion of life has been more rapid and remarkable than it had ever been before, in corresponding periods of abundant food and easy conditions; the contraction comes more quickly than it had ever done before. Mountain masses begin to rise in nearly all parts of the world. The advance is slow and not continuous, but as time goes on the Atlas, Alps, Pyrenees, Apennines, Caucasus, Himalaya, Rocky Mountains, and Andes rise higher and higher. When the geologist looks to-day for the floor of the Eocene ocean, which he recognises by the shells of the Nummulites, he finds it 10,000 feet above the sea-level in the Alps, 16,000 feet above the sea-level in the Himalaya, and 20,000 feet above the sea-level in Thibet. One need not ask why the regions of London and Paris fostered palms and magnolias and turtles in Tertiary times, and shudder in their dreary winter to-day. The Tertiary Era is divided by geologists into four periods: the Eocene, Oligocene, Miocene, and Pliocene. "Cene" is our barbaric way of expressing the Greek word for "new," and the classification is meant to mark the increase of new (or modern and actual) types of life in the course of the Tertiary Era. Many geologists, however, distrust the classification, and are disposed to divide the Tertiary into two periods. From our point of view, at least, it is advisable to do this. The first and longer half of the Tertiary is the period in which the temperature rises until Central Europe enjoys the climate of South Africa; the second half is the period in which the land gradually rises, and the temperature falls, until glaciers and sheets of ice cover regions where the palm and fig had flourished. The rise of the land had begun in the first half of the Tertiary, but had been suspended. The Pyrenees and Apennines had begun to rise at the end of the Eocene, straining the crust until it spluttered with volcanoes, casting the nummulitic sea off large areas of Southern Europe. The Nummulites become smaller and less abundant. There is also some upheaval in North America, and a bridge of land begins to connect the north and south, and permit an effective mingling of their populations. But the advance is, as I said, suspended, and the Oligocene period maintains the golden age. With the Miocene period the land resumes its rise. A chill is felt along the American coast, showing a fall in the temperature of the Atlantic. In Europe there is a similar chill, and a more obvious reason for it. There is an ascending movement of the whole series of mountains from Morocco and the Pyrenees, through the Alps, the Caucasus, and the Carpathians, to India and China. Large lakes still lie over Western Europe, but nearly the whole of it emerges from the ocean. The Mediterranean still sends an arm up France, and with another arm encircles the Alpine mass; but the upheaval continues, and the great nummulitic sea is reduced to a series of extensive lakes, cut off both from the Atlantic and Pacific. The climate of Southern Europe is probably still as genial as that of the Canaries to-day. Palms still linger in the landscape in reduced numbers. The last part of the Tertiary, the Pliocene, opens with a slight return of the sea. The upheaval is once more suspended, and the waters are eating into the land. There is some foundering of land at the south-western tip of Europe; the "Straits of Gibraltar" begin to connect the Mediterranean with the Atlantic, and the Balearic Islands, Corsica, and Sardinia remain as the mountain summits of a submerged land. Then the upheaval is resumed, in nearly every part of the earth. Nearly every great mountain chain that the geologist has studied shared in this remarkable movement at the end of the Tertiary Era. The Pyrenees, Alps, Himalaya, etc., made their last ascent, and attained their present elevation. And as the land rose, the aspect of Europe and America slowly altered. The palms, figs, bamboos, and magnolias disappeared; the turtles, crocodiles, flamingoes, and hippopotamuses retreated toward the equator. The snow began to gather thick on the rising heights; then the glaciers began to glitter on their flanks. As the cold increased, the rivers of ice which flowed down the hills of Switzerland, Spain, Scotland, or Scandinavia advanced farther and farther over the plains. The regions of green vegetation shrank before the oncoming ice, the animals retreated south, or developed Arctic features. Europe and America were ushering in the great Ice-Age, which was to bury five or six million square miles of their territory under a thick mantle of ice. Such is the general outline of the story of the Tertiary Era. We approach the study of its types of life and their remarkable development more intelligently when we have first given careful attention to this extraordinary series of physical changes. Short as the Era is, compared with its predecessors, it is even more eventful and stimulating than they, and closes with what Professor Chamberlin calls "the greatest deformative movements in post-Cambrian history." In the main it has, from the evolutionary point of view, the same significant character as the two preceding eras. Its middle portion is an age of expansion, indulgence, exuberance, in which myriads of varied forms are thrown upon the scene, its later part is an age of contraction, of annihilation, of drastic test, in which the more effectively organised will be chosen from the myriads of types. Once more nature has engendered a vast brood, and is about to select some of her offspring to people the modern world. Among the types selected will be Man. CHAPTER XVI. THE FLOWER AND THE INSECT AS we approach the last part of the geological record we must neglect the lower types of life, which have hitherto occupied so much of our attention, so that we may inquire more fully into the origin and fortunes of the higher forms which now fill the stage. It may be noted, in general terms, that they shared the opulence of the mid-Tertiary period, produced some gigantic specimens of their respective families, and evolved into the genera, and often the species, which we find living to-day. A few illustrations will suffice to give some idea of the later development of the lower invertebrates and vertebrates. Monstrous oysters bear witness to the prosperity of that ancient and interesting family of the Molluscs. In some species the shells were commonly ten inches long; the double shell of one of these Tertiary bivalves has been found which measured thirteen inches in length, eight in width, and six in thickness. In the higher branch of the Mollusc world the naked Cephalopods (cuttle-fish, etc.) predominate over the nautiloids--the shrunken survivors of the great coiled-shell race. Among the sharks, the modern Squalodonts entirely displace the older types, and grow to an enormous size. Some of the teeth we find in Tertiary deposits are more than six inches long and six inches broad at the base. This is three times the size of the teeth of the largest living shark, and it is therefore believed that the extinct possessor of these formidable teeth (Carcharodon megalodon) must have been much more than fifty, and was possibly a hundred, feet in length. He flourished in the waters of both Europe and America during the halcyon days of the Tertiary Era. Among the bony fishes, all our modern and familiar types appear. The amphibia and reptiles also pass into their modern types, after a period of generous expansion. Primitive frogs and toads make their first appearance in the Tertiary, and the remains are found in European beds of four-foot-long salamanders. More than fifty species of Tertiary turtles are known, and many of them were of enormous size. One carapace that has been found in a Tertiary bed measures twelve feet in length, eight feet in width, and seven feet in height to the top of the back. The living turtle must have been nearly twenty feet long. Marine reptiles, of a snake-like structure, ran to fifteen feet in length. Crocodiles and alligators swarmed in the rivers of Europe until the chilly Pliocene bade them depart to Africa. In a word, it was the seven years of plenty for the whole living world, and the expansive development gave birth to the modern types, which were to be selected from the crowd in the subsequent seven years of famine. We must be content to follow the evolution of the higher types of organisms. I will therefore first describe the advance of the Tertiary vegetation, the luxuriance of which was the first condition of the great expansion of animal life; then we will glance at the grand army of the insects which followed the development of the flowers, and at the accompanying expansion and ramification of the birds. The long and interesting story of the mammals must be told in a separate chapter, and a further chapter must be devoted to the appearance of the human species. We saw that the Angiosperms, or flowering plants, appeared at the beginning of the Cretaceous period, and were richly developed before the Tertiary Era opened. We saw also that their precise origin is unknown. They suddenly invade a part of North America where there were conditions for preserving some traces of them, but we have as yet no remains of their early forms or clue to their place of development. We may conjecture that their ancestors had been living in some elevated inland region during the warmth of the Jurassic period. As it is now known that many of the cycad-like Mesozoic plants bore flowers--as the modern botanist scarcely hesitates to call them--the gap between the Gymnosperms and Angiosperms is very much lessened. There are, however, structural differences which forbid us to regard any of these flowering cycads, which we have yet found, as the ancestors of the Angiosperms. The most reasonable view seems to be that a small and local branch of these primitive flowering plants was evolved, like the rest, in the stress of the Permian-Triassic cold; that, instead of descending to the warm moist levels with the rest at the end of the Triassic, and developing the definite characters of the cycad, it remained on the higher and cooler land; and that the rise of land at the end of the Jurassic period stimulated the development of its Angiosperm features, enlarged the area in which it was especially fitted to thrive, and so permitted it to spread and suddenly break into the geological record as a fully developed Angiosperm. As the cycads shrank in the Cretaceous period, the Angiosperms deployed with great rapidity, and, spreading at various levels and in different kinds of soils and climates, branched into hundreds of different types. We saw that the oak, beech, elm, maple, palm, grass, etc., were well developed before the end of the Cretaceous period. The botanist divides the Angiosperms into two leading groups, the Monocotyledons (palms, grasses, lilies, orchises, irises, etc.) and Dicotyledons (the vast majority), and it is now generally believed that the former were developed from an early and primitive branch of the latter. But it is impossible to retrace the lines of development of the innumerable types of Angiosperms. The geologist has mainly to rely on a few stray leaves that were swept into the lakes and preserved in the mud, and the evidence they afford is far too slender for the construction of genealogical trees. The student of living plants can go a little further in discovering relationships, and, when we find him tracing such apparently remote plants as the apple and the strawberry to a common ancestor with the rose, we foresee interesting possibilities on the botanical side. But the evolution of the Angiosperms is a recent and immature study, and we will be content with a few reflections on the struggle of the various types of trees in the changing conditions of the Tertiary, the development of the grasses, and the evolution of the flower. In other words, we will be content to ask how the modern landscape obtained its general vegetal features. Broadly speaking, the vegetation of the first part of the Tertiary Era was a mixture of sub-tropical and temperate forms, a confused mass of Ferns, Conifers, Ginkgoales, Monocotyledons, and Dicotyledons. Here is a casual list of plants that then grew in the latitude of London and Paris: the palm, magnolia, myrtle, Banksia, vine, fig, aralea, sequoia, eucalyptus, cinnamon tree, cactus, agave, tulip tree, apple, plum, bamboo, almond, plane, maple, willow, oak, evergreen oak, laurel, beech, cedar, etc. The landscape must have been extraordinarily varied and beautiful and rich. To one botanist it suggests Malaysia, to another India, to another Australia. It is really the last gathering of the plants, before the great dispersion. Then the cold creeps slowly down from the Arctic regions, and begins to reduce the variety. We can clearly trace its gradual advance. In the Carboniferous and Jurassic the vegetation of the Arctic regions had been the same as that of England; in the Eocene palms can flourish in England, but not further north; in the Pliocene the palms and bamboos and semi-tropical species are driven out of Europe; in the Pleistocene the ice-sheet advances to the valleys of the Thames and the Danube (and proportionately in the United States), every warmth-loving species is annihilated, and our grasses, oaks, beeches, elms, apples, plums, etc., linger on the green southern fringe of the Continent, and in a few uncovered regions, ready to spread north once more as the ice creeps back towards the Alps or the Arctic circle. Thus, in few words, did Europe and North America come to have the vegetation we find in them to-day. The next broad characteristic of our landscape is the spreading carpet of grass. The interest of the evolution of the grasses will be seen later, when we shall find the evolution of the horse, for instance, following very closely upon it. So striking, indeed, is the connection between the advance of the grasses and the advance of the mammals that Dr. Russel Wallace has recently claimed ("The World of Life," 1910) that there is a clear purposive arrangement in the whole chain of developments which leads to the appearance of the grasses. He says that "the very puzzling facts" of the immense reptilian development in the Mesozoic can only be understood on the supposition that they were evolved "to keep down the coarser vegetation, to supply animal food for the larger Carnivora, and thus give time for higher forms to obtain a secure foothold and a sufficient amount of varied form and structure" (p. 284). Every insistence on the close connection of the different strands in the web of life is welcome, but Dr. Wallace does not seem to have learned the facts accurately. There is nothing "puzzling" about the Mesozoic reptilian development; the depression of the land, the moist warmth, and the luscious vegetation of the later Triassic and the Jurassic amply explain it. Again, the only carnivores to whom they seem to have supplied food were reptiles of their own race. Nor can the feeding of the herbivorous reptiles be connected with the rise of the Angiosperms. We do not find the flowering plants developing anywhere in those vast regions where the great reptiles abounded; they invade them from some single unknown region, and mingle with the pines and ginkgoes, while the cyeads alone are destroyed. The grasses, in particular, do not appear until the Cretaceous, and do not show much development until the mid-Tertiary; and their development seems to be chiefly connected with physical conditions. The meandering rivers and broad lakes of the mid-Tertiary would have their fringes of grass and sedge, and, as the lakes dried up in the vicissitudes of climate, large areas of grass would be left on their sites. To these primitive prairies the mammal (not reptile) herbivores would be attracted, with important results. The consequences to the animals we will consider presently. The effect on the grasses may be well understood on the lines so usefully indicated in Dr. Wallace's book. The incessant cropping, age after age, would check the growth of the larger and coarser grasses give opportunity to the smaller and finer, and lead in time to the development of the grassy plains of the modern world. Thus one more familiar feature was added to the landscape in the Tertiary Era. As this fresh green carpet spread over the formerly naked plains, it began to be enriched with our coloured flowers. There were large flowers, we saw, on some of the Mesozoic cycads, but their sober yellows and greens--to judge from their descendants--would do little to brighten the landscape. It is in the course of the Tertiary Era that the mantle of green begins to be embroidered with the brilliant hues of our flowers. Grant Allen put forward in 1882 ("The Colours of Flowers") an interesting theory of the appearance of the colours of flowers, and it is regarded as probable. He observed that most of the simplest flowers are yellow; the more advanced flowers of simple families, and the simpler flowers of slightly advanced families, are generally white or pink; the most advanced flowers of all families, and almost all the flowers of the more advanced families, are red, purple, or blue; and the most advanced flowers of the most advanced families are always either blue or variegated. Professor Henslow adds a number of equally significant facts with the same tendency, so that we have strong reason to conceive the floral world as passing through successive phases of colour in the Tertiary Era. At first it would be a world of yellows and greens, like that of the Mesozoic vegetation, but brighter. In time splashes of red and white would lie on the face of the landscape; and later would come the purples, the rich blues, and the variegated colours of the more advanced flowers. Why the colours came at all is a question closely connected with the general story of the evolution of the flower, at which we must glance. The essential characteristic of the flower, in the botanist's judgment, is the central green organ which you find--say, in a lily--standing out in the middle of the floral structure, with a number of yellow-coated rods round it. The yellow rods bear the male germinal elements (pollen); the central pistil encloses the ovules, or female elements. "Angiosperm" means "covered-seed plant," and its characteristic is this protection of the ovules within a special chamber, to which the pollen alone may penetrate. Round these essential organs are the coloured petals of the corolla (the chief part of the flower to the unscientific mind) and the sepals, often also coloured, of the calyx. There is no doubt that all these parts arose from modifications of the leaves or stems of the primitive plant; though whether the bright leaves of the corolla are directly derived from ordinary leaves, or are enlarged and flattened stamens, has been disputed. And to the question why these bright petals, whose colour and variety of form lend such charm to the world of flowers, have been developed at all, most botanists will give a prompt and very interesting reply. As both male and female elements are usually in one flower, it may fertilise itself, the pollen falling directly on the pistil. But fertilisation is more sure and effective if the pollen comes from a different individual--if there is "cross fertilisation." This may be accomplished by the simple agency of the wind blowing the pollen broadcast, but it is done much better by insects, which brush against the stamens, and carry grains of the pollen to the next flower they visit. We have here a very fertile line of development among the primitive flowers. The insects begin to visit them, for their pollen or juices, and cross-fertilise them. If this is an advantage, attractiveness to insects will become so important a feature that natural selection will develop it more and more. In plain English, what is meant is that those flowers which are more attractive to insects will be the most surely fertilised and breed most, and the prolonged application of this principle during hundreds of thousands of years will issue in the immense variety of our flowers. They will be enriched with little stores of honey and nectar; not so mysterious an advantage, when we reflect on the concentration of the juices in the neighbourhood of the seed. Then they must "advertise" their stores, and the strong perfumes and bright colours begin to develop, and ensure posterity to their possessors. The shape of the corolla will be altered in hundreds of ways, to accommodate and attract the useful visitor and shut out the mere robber. These utilities, together with the various modifying agencies of different environments, are generally believed to have led to the bewildering variety and great beauty of our floral world. It is proper to add that this view has been sharply challenged by a number of recent writers. It is questioned if colours and scents do attract insects; though several recent series of experiments seem to show that bees are certainly attracted by colours. It is questioned if cross-fertilisation has really the importance ascribed to it since the days of Darwin. Some of these writers believe that the colours and the peculiar shape which the petals take in some flowers (orchises, for instance) have been evolved to deter browsing animals from eating them. The theory is thus only a different application of natural selection; Professor Henslow, on the other hand, stands alone in denying the selection, and believing that the insects directly developed the scents, honeys, colours, and shapes by mechanical irritation. The great majority of botanists adhere to the older view, and see in the wonderful Tertiary expansion of the flowers a manifold adaptation to the insect friends and insect foes which then became very abundant and varied. Resisting the temptation to glance at the marvellous adaptations which we find to-day in our plant world--the insect-eating plants, the climbers, the parasites, the sensitive plants, the water-storing plants in dry regions, and so on--we must turn to the consideration of the insects themselves. We have already studied the evolution of the insect in general, and seen its earlier forms. The Tertiary Era not only witnessed a great deployment of the insects, but was singularly rich in means of preserving them. The "fly in amber" has ceased to be a puzzle even to the inexpert. Amber is the resin that exuded from pine-like trees, especially in the Baltic region, in the Eocene and Oligocene periods. Insects stuck in the resin, and were buried under fresh layers of it, and we find them embalmed in it as we pick up the resin on the shores of the Baltic to-day. The Tertiary lakes were also important cemeteries of insects. A great bed at Florissart, in Colorado, is described by one of the American experts who examined it as "a Tertiary Pompeii." It has yielded specimens of about a thousand species of Tertiary insects. Near the large ancient lake, of which it marks the site, was a volcano, and the fine ash yielded from the cone seems to have buried myriads of insects in the water. At Oeningen a similar lake-deposit has, although only a few feet thick, yielded 900 species of insects. Yet these rich and numerous finds throw little light on the evolution of the insect, except in the general sense that they show species and even genera quite different from those of to-day. No new families of insects have appeared since the Eocene, and the ancient types had by that time disappeared. Since the Eocene, however, the species have been almost entirely changed, so that the insect record, from its commencement in the Primary Era, has the stamp of evolution on every page of it. Unfortunately, insects, especially the higher and later insects, are such frail structures that they are only preserved in very rare conditions. The most important event of the insect-world in the Tertiary is the arrival of the butterflies, which then appear for the first time. We may assume that they spread with great rapidity and abundance in the rich floral world of the mid-Jurassic. More than 13,000 species of Lepidoptera are known to-day, and there are probably twice that number yet to be classified by the entomologist. But so far the Tertiary deposits have yielded only the fragmentary remains of about twenty individual butterflies. The evolutionary study of the insects is, therefore, not so much concerned with the various modifications of the three pairs of jaws, inherited from the primitive Tracheate, and the wings, which have given us our vast variety of species. It is directed rather to the more interesting questions of what are called the "instincts" of the insects, the remarkable metamorphosis by which the young of the higher orders attain the adult form, and the extraordinary colouring and marking of bees, wasps, and butterflies. Even these questions, however, are so large that only a few words can be said here on the tendencies of recent research. In regard to the psychic powers of insects it may be said, in the first place, that it is seriously disputed among the modern authorities whether even the highest insects (the ant, bee, and wasp) have any degree whatever of the intelligence which an earlier generation generously bestowed on them. Wasmann and Bethe, two of the leading authorities on ants, take the negative view; Forel claims that they show occasional traces of intelligence. It is at all events clear that the enormous majority of, if not all, their activities--and especially those activities of the ant and the bee which chiefly impress the imagination--are not intelligent, but instinctive actions. And the second point to be noted is that the word "instinct," in the old sense of some innate power or faculty directing the life of an animal, has been struck out of the modern scientific dictionary. The ant or bee inherits a certain mechanism of nerves and muscles which will, in certain circumstances, act in the way we call "instinctive." The problem is to find how this mechanism and its remarkable actions were slowly evolved. In view of the innumerable and infinitely varied forms of "instinct" in the insect world we must restrict ourselves to a single illustration--say, the social life of the ants and the bees. We are not without indications of the gradual development of this social life. In the case of the ant we find that the Tertiary specimens--and about a hundred species are found in Switzerland alone, whereas there are only fifty species in the whole of Europe to-day--all have wings and are, apparently, of the two sexes, not neutral. This seems to indicate that even in the mid-Tertiary some millions of years after the first appearance of the ant, the social life which we admire in the ants today had not yet been developed. The Tertiary bees, on the other hand, are said to show some traces of the division of labour (and modification of structure) which make the bees so interesting; but in this case the living bees, rising from a solitary life through increasing stages of social co-operation, give us some idea of the gradual development of this remarkable citizenship. It seems to me that the great selective agency which has brought about these, and many other remarkable activities of the insects (such as the storing of food with their eggs by wasps), was probably the occurrence of periods of cold, and especially the beginning of a winter season in the Cretaceous or Tertiary age. In the periods of luxuriant life (the Carboniferous, the Jurassic, or the Oligocene), when insects swarmed and varied in every direction, some would vary in the direction of a more effective placing of the eggs; and the supervening period of cold and scarcity would favour them. When a regular winter season set in, this tendency would be enormously increased. It is a parallel case to the evolution of the birds and mammals from the reptiles. Those that varied most in the direction of care for the egg and the young would have the largest share in the next generation. When we further reflect that since the Tertiary the insect world has passed through the drastic disturbance of the climate in the great Ice-Age, we seem to have an illuminating clue to one of the most remarkable features of higher insect life. The origin of the colour marks' and patterns on so many of the higher insects, with which we may join the origin of the stick-insects, leaf-insects, etc., is a subject of lively controversy in science to-day. The protective value of the appearance of insects which look almost exactly like dried twigs or decaying leaves, and of an arrangement of the colours of the wings of butterflies which makes them almost invisible when at rest, is so obvious that natural selection was confidently invoked to explain them. In other cases certain colours or marks seemed to have a value as "warning colours," advertising the nauseousness of their possessors to the bird, which had learned to recognise them; in other cases these colours and marks seemed to be borrowed by palatable species, whose unconscious "mimicry" led to their survival; in other cases, again, the patterns and spots were regarded as "recognition marks," by which the male could find his mate. Science is just now passing through a phase of acute criticism--as the reader will have realised by this time--and many of the positions confidently adopted in the earlier constructive stage are challenged. This applies to the protective colours, warning colours, mimicry, etc., of insects. Probably some of the affirmations of the older generation of evolutionists were too rigid and extensive; and probably the denials of the new generation are equally exaggerated. When all sound criticism has been met, there remains a vast amount of protective colouring, shaping, and marking in the insect world of which natural selection gives us the one plausible explanation. But the doctrine of natural selection does not mean that every feature of an animal shall have a certain utility. It will destroy animals with injurious variations and favour animals with useful variations; but there may be a large amount of variation, especially in colour, to which it is quite indifferent. In this way much colour-marking may develop, either from ordinary embryonic variations or (as experiment on butterflies shows) from the direct influence of surroundings which has no vital significance. In this way, too, small variations of no selective value may gradually increase until they chance to have a value to the animal. [*] * For a strong statement of the new critical position see Dewar and Finn's "Making of Species," 1909, ch. vi. The origin of the metamorphosis, or pupa-stage, of the higher insects, with all its wonderful protective devices, is so obscure and controverted that we must pass over it. Some authorities think that the sleep-stage has been evolved for the protection of the helpless transforming insect; some believe that it occurs because movement would be injurious to the insect in that stage; some say that the muscular system is actually dissolved in its connections; and some recent experts suggest that it is a reminiscence of the fact that the ancestors of the metamorphosing insects were addicted to internal parasitism in their youth. It is one of the problems of the future. At present we have no fossil pupa-remains (though we have one caterpillar) to guide us. We must leave these fascinating but difficult problems of insect life, and glance at the evolution of the birds. To the student of nature whose interest is confined to one branch of science the record of life is a mysterious Succession of waves. A comprehensive view of nature, living and non-living, past and present, discovers scores of illuminating connections, and even sees at times the inevitable sequence of events. Thus if the rise of the Angiospermous vegetation on the ruins of the Mesozoic world is understood in the light of geological and climatic changes, and the consequent deploying of the insects, especially the suctorial insects, is a natural result, the simultaneous triumph of the birds is not unintelligible. The grains and fruits of the Angiosperms and the vast swarms of insects provided immense stores of food; the annihilation of the Pterosaurs left a whole stratum of the earth free for their occupation. We saw that a primitive bird, with very striking reptilian features, was found in the Jurassic rocks, suggesting very clearly the evolution of the bird from the reptile in the cold of the Permian or Triassic period. In the Cretaceous we found the birds distributed in a number of genera, but of two leading types. The Ichthyornis type was a tern-like flying bird, with socketed teeth and biconcave vertebrae like the reptile, but otherwise fully evolved into a bird. Its line is believed to survive in the gannets, cormorants, pelicans, and frigate-birds of to-day. The less numerous Hesperornis group were large and powerful divers. Then there is a blank in the record, representing the Cretaceous upheaval, and it unfortunately conceals the first great ramification of the bird world. When the light falls again on the Eocene period we find great numbers of our familiar types quite developed. Primitive types of gulls, herons, pelicans, quails, ibises, flamingoes, albatrosses, buzzards, hornbills, falcons, eagles, owls, plovers, and woodcocks are found in the Eocene beds; the Oligocene beds add parrots, trogons, cranes, marabouts, secretary-birds, grouse, swallows, and woodpeckers. We cannot suppose that every type has been preserved, but we see that our bird-world was virtually created in the early part of the Tertiary Era. With these more or less familiar types were large ostrich-like survivors of the older order. In the bed of the sea which covered the site of London in the Eocene are found the remains of a toothed bird (Odontopteryx), though the teeth are merely sharp outgrowths of the edge of the bill. Another bird of the same period and region (Gastornis) stood about ten feet high, and must have looked something like a wading ostrich. Other large waders, even more ostrich-like in structure, lived in North America; and in Patagonia the remains have been found of a massive bird, about eight feet high, with a head larger than that of any living animal except the elephant, rhinoceros, and hippopotamus (Chamberlin). The absence of early Eocene remains prevents us from tracing the lines of our vast and varied bird-kingdom to their Mesozoic beginnings. And when we appeal to the zoologist to supply the missing links of relationship, by a comparison of the structures of living birds, we receive only uncertain and very general suggestions. [*] He tells us that the ostrich-group (especially the emus and cassowaries) are one of the most primitive stocks of the bird world, and that the ancient Dinornis group and the recently extinct moas seem to be offshoots of that stock. The remaining many thousand species of Carinate birds (or flying birds with a keel [carina]-shaped breast-bone for the attachment of the flying muscles) are then gathered into two great branches, which are "traceable to a common stock" (Pycraft), and branch in their turn along the later lines of development. One of these lines--the pelicans, cormorants, etc.--seems to be a continuation of the Ichthyornis type of the Cretaceous, with the Odontopteryx as an Eocene offshoot; the divers, penguins, grebes, and petrels represent another ancient stock, which may be related to the Hesperornis group of the Cretaceous. Dr. Chalmers Mitchell thinks that the "screamers" of South America are the nearest representatives of the common ancestor of the keel-breasted birds. But even to give the broader divisions of the 19,000 species of living birds would be of little interest to the general reader. * The best treatment of the subject will be found in W. P. Pycraft's History of Birds, 1910. The special problems of bird-evolution are as numerous and unsettled as those of the insects. There is the same dispute as to "protective colours" and "recognition marks", the same uncertainty as to the origin of such instinctive practices as migration and nesting. The general feeling is that the annual migration had its origin in the overcrowding of the regions in which birds could live all the year round. They therefore pushed northward in the spring and remained north until the winter impoverishment drove them south again. On this view each group would be returning to its ancestral home, led by the older birds, in the great migration flights. The curious paths they follow are believed by some authorities to mark the original lines of their spread, preserved from generation to generation through the annual lead of the older birds. If we recollect the Ice-Age which drove the vast majority of the birds south at the end of the Tertiary, and imagine them later following the northward retreat of the ice, from their narrowed and overcrowded southern territory, we may not be far from the secret of the annual migration. A more important controversy is conducted in regard to the gorgeous plumage and other decorations and weapons of the male birds. Darwin, as is known, advanced a theory of "sexual selection" to explain these. The male peacock, to take a concrete instance, would have developed its beautiful tail because, through tens of thousands of generations, the female selected the more finely tailed male among the various suitors. Dr. Wallace and other authorities always disputed this aesthetic sentiment and choice on the part of the female. The general opinion today is that Darwin's theory could not be sustained in the range and precise sense he gave to it. Some kind of display by the male in the breeding season would be an advantage, but to suppose that the females of any species of birds or mammals had the definite and uniform taste necessary for the creation of male characters by sexual selection is more than difficult. They seem to be connected in origin rather with the higher vitality of the male, but the lines on which they were selected are not yet understood. This general sketch of the enrichment of the earth with flowering plants, insects, and birds in the Tertiary Era is all that the limits of the present work permit us to give. It is an age of exuberant life and abundant food; the teeming populations overflow their primitive boundaries, and, in adapting themselves to every form of diet, every phase of environment, and every device of capture or escape, the spreading organisms are moulded into tens of thousands of species. We shall see this more clearly in the evolution of the mammals. What we chiefly learn from the present chapter is the vital interconnection of the various parts of nature. Geological changes favour the spread of a certain type of vegetation. Insects are attracted to its nutritious seed-organs, and an age of this form of parasitism leads to a signal modification of the jaws of the insects themselves and to the lavish variety and brilliance of the flowers. Birds are attracted to the nutritious matter enclosing the seeds, and, as it is an advantage to the plant that its seeds be scattered beyond the already populated area, by passing through the alimentary canal of the bird, and being discharged with its excrements, a fresh line of evolution leads to the appearance of the large and coloured fruits. The birds, again, turn upon the swarming insects, and the steady selection they exercise leads to the zigzag flight and the protective colour of the butterfly, the concealment of the grub and the pupa, the marking of the caterpillar, and so on. We can understand the living nature of to-day as the outcome of that teeming, striving, changing world of the Tertiary Era, just as it in turn was the natural outcome of the ages that had gone before. CHAPTER XVII. THE ORIGIN OF OUR MAMMALS In our study of the evolution of the plant, the insect, and the bird we were seriously thwarted by the circumstance that their frames, somewhat frail in themselves, were rarely likely to be entombed in good conditions for preservation. Earlier critics of evolution used, when they were imperfectly acquainted with the conditions of fossilisation, to insinuate that this fragmentary nature of the geological record was a very convenient refuge for the evolutionist who was pressed for positive evidence. The complaint is no longer found in any serious work. Where we find excellent conditions for preservation, and animals suitable for preservation living in the midst of them, the record is quite satisfactory. We saw how the chalk has yielded remains of sea-urchins in the actual and gradual process of evolution. Tertiary beds which represent the muddy bottoms of tranquil lakes are sometimes equally instructive in their fossils, especially of shell-fish. The Paludina of a certain Slavonian lake-deposit is a classical example. It changes so greatly in the successive levels of the deposit that, if the intermediate forms were not preserved, we should divide it into several different species. The Planorbis is another well-known example. In this case we have a species evolving along several distinct lines into forms which differ remarkably from each other. The Tertiary mammals, living generally on the land and only coming by accident into deposits suitable for preservation, cannot be expected to reveal anything like this sensible advance from form to form. They were, however, so numerous in the mid-Tertiary, and their bones are so well calculated to survive when they do fall into suitable conditions, that we can follow their development much more easily than that of the birds. We find a number of strange patriarchal beasts entering the scene in the early Eocene, and spreading into a great variety of forms in the genial conditions of the Oligocene and Miocene. As some of these forms advance, we begin to descry in them the features, remote and shadowy at first, of the horse, the deer, the elephant, the whale, the tiger, and our other familiar mammals. In some instances we can trace the evolution with a wonderful fullness, considering the remoteness of the period and the conditions of preservation. Then, one by one, the abortive, the inelastic, the ill-fitted types are destroyed by changing conditions or powerful carnivores, and the field is left to the mammals which filled it when man in turn began his destructive career. The first point of interest is the origin of these Tertiary mammals. Their distinctive advantage over the mammals of the Mesozoic Era was-the possession by the mother of a placenta (the "after-birth" of the higher mammals), or structure in the womb by which the blood-vessels of the mother are brought into such association with those of the foetus that her blood passes into its arteries, and it is fully developed within the warm shelter of her womb. The mammals of the Mesozoic had been small and primitive animals, rarely larger than a rat, and never rising above the marsupial stage in organisation. They not only continued to exist, and give rise to their modern representatives (the opossum, etc.) during the Tertiary Era, but they shared the general prosperity. In Australia, where they were protected from the higher carnivorous mammals, they gave rise to huge elephant-like wombats (Diprotodon), with skulls two or three feet in length. Over the earth generally, however, they were superseded by the placental mammals, which suddenly break into the geological record in the early Tertiary, and spread with great vigour and rapidity over the four continents. Were they a progressive offshoot from the Mesozoic Marsupials, or Monotremes, or do they represent a separate stock from the primitive half-reptile and half-mammal family? The point is disputed; nor does the scantiness of the record permit us to tell the place of their origin. The placental structure would be so great an advantage in a cold and unfavourable environment that some writers look to the northern land, connecting Europe and America, for their development. We saw, however, that this northern region was singularly warm until long after the spread of the mammals. Other experts, impressed by the parallel development of the mammals and the flowering plants, look to the elevated parts of eastern North America. Such evidence as there is seems rather to suggest that South Africa was the cradle of the placental mammals. We shall find that many of our mammals originated in Africa; there, too, is found to-day the most primitive representative of the Tertiary mammals, the hyrax; and there we find in especial abundance the remains of the mammal-like reptiles (Theromorphs) which are regarded as their progenitors. Further search in the unexplored geological treasures and dense forests of Africa is needed. We may provisionally conceive the placental mammals as a group of the South African early mammals which developed a fortunate variation in womb-structure during the severe conditions of the early Mesozoic. In this new structure they would have no preponderant advantage as long as the genial Jurassic age favoured the great reptiles, and they may have remained as small and insignificant as the Marsupials. But with the fresh upheaval and climatic disturbance at the end of the Jurassic, and during the Cretaceous, they spread northward, and replaced the dying reptiles, as the Angiosperms replaced the dying cycads. When they met the spread of the Angiosperm vegetation they would receive another great stimulus to development. They appear in Europe and North America in the earliest Cretaceous. The rise of the land had connected many hitherto isolated regions, and they seem to have poured over every bridge into all parts of the four continents. The obscurity of their origin is richly compensated by their intense evolutionary interest from the moment they enter the geological record. We have seen this in the case of every important group of plants and animals, and can easily understand it. The ancestral group was small and local; the descendants are widely spread. While, therefore, we discover remains of the later phases of development in our casual cuttings and quarries, the ancestral tomb may remain for ages in some unexplored province of the geological world. If this region is, as we suspect, in Africa, our failure to discover it as yet is all the more intelligible. But these mammals of the early Tertiary are still of such a patriarchal or ancestral character that the student of evolution can dispense with their earlier phase. They combine in their primitive frames, in an elementary way, the features which we now find distributed in widely removed groups of their descendants. Most of them fall into two large orders: the Condylarthra, the ancestral herbivores from which we shall find our horses, oxen, deer, elephants, and hogs gradually issuing, and the Creodonta, the patriarchal carnivores, which will give birth to our lions and tigers, wolves and foxes, and their various cousins. As yet even the two general types of herbivore and carnivore are so imperfectly separated that it is not always possible to distinguish between them. Nearly all of them have the five-toed foot of the reptile ancestor; and the flat nails on their toes are the common material out of which the hoof of the ungulate and the claw of the carnivore will be presently fashioned. Nearly all have forty-four simply constructed teeth, from which will be evolved the grinders and tusks of the elephant or the canines of the tiger. They answer in every respect to the theory that some primitive local group was the common source of all our great mammals. With them are ancestral forms of Edentates (sloths, etc.) and Insectivores (moles, etc.), side-branches developing according to their special habits; and before the end of the Eocene we find primitive Rodents (squirrels, etc.) and Cheiroptera (bats). From the description of the Tertiary world which we have seen in the last chapter we understand the rapid evolution of the herbivorous Condylarthra. The rich vegetation which spreads over the northern continents, to which they have penetrated, gives them an enormous vitality and fecundity, and they break into groups, as they increase in number, adapted to the different conditions of forest, marsh, or grass-covered plain. Some of them, swelling lazily on the abundant food, and secure for a time in their strength, become the Deinosaurs of their age, mere feeding and breeding machines. They are massive, sluggish, small-brained animals, their strong stumpy limbs terminating in broad five-toed feet. Coryphodon, sometimes as large as an ox, is a typical representative. It is a type fitted only for prosperous days, and these Amblypoda, as they are called, will disappear as soon as the great carnivores are developed. Another doomed race, or abortive experiment of early mammal life, were the remarkable Deinocerata ("terrible-horned" mammals). They sometimes measured thirteen feet in length, but had little use for brain in the conditions in which they were developed. The brain of the Deinoceras was only one-eighth the size of the brain of a rhinoceros of the same bulk; and the rhinoceros is a poor-brained representative of the modern mammals. To meet the growing perils of their race they seem to have developed three pairs of horns on their long, flat skulls, as we find on them three pairs of protuberances. A late specimen of the group, Tinoceras, had a head four feet in length, armed with these six horns, and its canine teeth were developed into tusks sometimes seven or eight inches in length. They suggest a race of powerful but clumsy and grotesque monsters, making a last stand, and developing such means of protection as their inelastic nature permitted. But the horns seem to have proved a futile protection against the advancing carnivores, and the race was extinguished. The horns may, of course, have been mainly developed by, or for, the mutual butting of the males. The extinction of these races will remind many readers of a theory on which it is advisable to say a word. It will be remembered that the last of the Deinosaurs and the Ammonites also exhibited some remarkable developments in their last days. These facts have suggested to some writers the idea that expiring races pass through a death-agony, and seem to die a natural death of old age like individuals. The Trilobites are quoted as another instance; and some ingenious writers add the supposed eccentricities of the Roman Empire in its senile decay and a number of other equally unsubstantial illustrations. There is not the least ground for this fantastic speculation. The destruction of these "doomed races" is as clearly traceable to external causes as is the destruction of the Roman Empire; nor, in fact, did the Roman Empire develop any such eccentricities as are imagined in this superficial theory. What seem to our eye the "eccentricities" and "convulsions" of the Ceratopsia and Deinocerata are much more likely to be defensive developments against a growing peril, but they were as futile against the new carnivores as were the assegais of the Zulus against the European. On the other hand, the eccentricities of many of the later Trilobites--the LATEST Trilobites, it may be noted, were chaste and sober specimens of their race, like the last Roman patricians--and of the Ammonites may very well have been caused by physical and chemical changes in the sea-water. We know from experiment that such changes have a disturbing influence, especially on the development of eggs and larvae; and we know from the geological record that such changes occurred in the periods when the Trilobites and Ammonites perished. In fine, the vast majority of extinct races passed through no "convulsions" whatever. We may conclude that races do not die; they are killed. The extinction of these races of the early Condylarthra, and the survival of those races whose descendants share the earth with us to-day, are quite intelligible. The hand of natural selection lay heavy on the Tertiary herbivores. Apart from overpopulation, forcing groups to adapt themselves to different regions and diets, and apart from the geological disturbances and climatic changes which occurred in nearly every period, the shadow of the advancing carnivores was upon them. Primitive but formidable tigers, wolves, and hyenas were multiplying, and a great selective struggle set in. Some groups shrank from the battle by burrowing underground like the rabbit; some, like the squirrel or the ape, took refuge in the trees; some, like the whale and seal, returned to the water; some shrank into armour, like the armadillo, or behind fences of spines, like the hedgehog; some, like the bat, escaped into the air. Social life also was probably developed at this time, and the great herds had their sentinels and leaders. But the most useful qualities of the large vegetarians, which lived on grass and leaf, were acuteness of perception to see the danger, and speed of limb to escape it. In other words, increase of brain and sense-power and increase of speed were the primary requisites. The clumsy early Condylarthra failed to meet the tests, and perished; the other branches of the race were more plastic, and, under the pressure of a formidable enemy, were gradually moulded into the horse, the deer, the ox, the antelope, and the elephant. We can follow the evolution of our mammals of this branch most easily by studying the modification of the feet and limbs. In a running attitude--the experiment may be tried--the weight of the body is shifted from the flat sole of the foot, and thrown upon the toes, especially the central toes. This indicates the line of development of the Ungulates (hoofed animals) in the struggle of the Tertiary Era. In the early Eocene we find the Condylarthra (such as Phenacodus) with flat five-toed feet, and such a mixed combination of characters that they "might serve very well for the ancestors of all the later Ungulata" (Woodward). We then presently find this generalised Ungulate branching into three types, one of which seems to be a patriarchal tapir, the second is regarded as a very remote ancestor of the horse, and the third foreshadows the rhinoceros. The feet have now only three or four toes; one or two of the side-toes have disappeared. This evolution, however, follows two distinct lines. In one group of these primitive Ungulates the main axis of the limb, or the stress of the weight, passes through the middle toe. This group becomes the Perissodactyla ("odd-toed" Ungulates) of the zoologist, throwing out side-branches in the tapir and the rhinoceros, and culminating in the one-toed horse. In the other line, the Artiodactyla (the "even-toed" or cloven-hoofed Ungulates), the main axis or stress passes between the third and fourth toes, and the group branches into our deer, oxen, sheep, pigs, camels, giraffes, and hippopotamuses. The elephant has developed along a separate and very distinctive line, as we shall see, and the hyrax is a primitive survivor of the ancestral group. Thus the evolutionist is able to trace a very natural order in the immense variety of our Ungulates. He can follow them in theory as they slowly evolve from their primitive Eocene ancestor according to their various habits and environments; he has a very rich collection of fossil remains illustrating the stages of their development; and in the hyrax (or "coney") he has one more of those living fossils, or primitive survivors, which still fairly preserve the ancestral form. The hyrax has four toes on the front foot and three on the hind foot, and the feet are flat. Its front teeth resemble those of a rodent, and its molars those of the rhinoceros. In many respects it is a most primitive and generalised little animal, preserving the ancestral form more or less faithfully since Tertiary days in the shelter of the African Continent. The rest of the Ungulates continued to develop through the Tertiary, and fortunately we are enabled to follow the development of two of the most interesting of them, the horse and the elephant, in considerable detail. As I said above, the primitive Ungulate soon branches into three types which dimly foreshadow the tapir, the horse, and the rhinoceros, the three forms of the Perissodactyl. The second of these types is the Hyracotherium. It has no distinct equine features, and is known only from the skull, but the authorities regard it as the progenitor (or representative of the progenitors) of the horse-types. In size it must have been something like the rabbit or the hyrax. Still early in the Eocene, however, we find the remains of a small animal (Eohippus), about the size of a fox, which is described as "undoubtedly horse-like." It had only three toes on its hind feet, and four on its front feet; though it had also a splint-bone, representing the shrunken and discarded fifth toe, on its fore feet. Another form of the same period (Protorohippus) shows the central of the three toes on the hind foot much enlarged, and the lateral toes shrinking. The teeth, and the bones and joints of the limbs, are also developing in the direction of the horse. In the succeeding geological period, the Oligocene, we find several horse-types in which the adaptation of the limbs to running on the firm grassy plains and of the teeth to eating the grass continues. Mesohippus has lost the fourth toe of the fore foot, which is now reduced to a splintbone, and the lateral toes of its hind foot are shrinking. In the Miocene period there is a great development of the horse-like mammals. We have the remains of more than forty species, some continuing the main line of development on the firm and growing prairies of the Miocene, some branching into the softer meadows or the forests, and giving rise to types which will not outlive the Tertiary. They have three toes on each foot, and have generally lost even the rudimentary trace of the fourth toe. In most of them, moreover, the lateral toes--except in the marsh-dwelling species, with spreading feet--scarcely touch the ground, while the central toe is developing a strong hoof. The leg-bones are longer, and have a new type of joint; the muscles are concentrated near the body. The front teeth are now chopping incisors, and the grinding teeth approach those of the modern horse in the distribution of the enamel, dentine, and cement. They are now about the size of a donkey, and must have had a distinctly horsy appearance, with their long necks and heads and tapering limbs. One of them, Merychippus, was probably in the direct line of the evolution of the horse. From Hipparion some of the authorities believe that the zebras may have been developed. Miohippus, Protohippus, and Hypohippus, varying in size from that of a sheep to that of a donkey, are other branches of this spreading family. In the Pliocene period the evolution of the main stem culminates in the appearance of the horse, and the collateral branches are destroyed. Pliohippus is a further intermediate form. It has only one toe on each foot, with two large splint bones, but its hoof is less round than that of the horse, and it differs in the shape of the skull and the length of the teeth. The true horse (Equus) at length appears, in Europe and America, before the close of the Tertiary period. As is well known, it still has the rudimentary traces of its second and fourth toes in the shape of splint bones, and these bones are not only more definitely toe-shaped in the foal before birth, but are occasionally developed and give us a three-toed horse. From these successive remains we can confidently picture the evolution, during two or three million years, of one of our most familiar mammals. It must not, of course, be supposed that these fossil remains all represent "ancestors of the horse." In some cases they may very well do so; in others, as we saw, they represent sidebranches of the family which have become extinct. But even such successive forms as the Eohippus, Mesohippus, Miohippus, and Pliohippus must not be arranged in a direct line as the pedigree of the horse. The family became most extensive in the Miocene, and we must regard the casual fossil specimens we have discovered as illustrations of the various phases in the development of the horse from the primitive Ungulate. When we recollect what we saw in an earlier chapter about the evolution of grassy plains and the successive rises of the land during the Tertiary period, and when we reflect on the simultaneous advance of the carnivores, we can without difficulty realise this evolution of our familiar companion from a hyrax-like little animal of two million years ago. We have not in many cases so rich a collection of intermediate forms as in the case of the horse, but our fossil mammals are numerous enough to suggest a similar development of all the mammals of to-day. The primitive family which gave birth to the horse also gave us, as we saw, the tapir and the rhinoceros. We find ancestral tapirs in Europe and America during the Tertiary period, but the later cold has driven them to the warm swamps of Brazil and Malaysia. The rhinoceros has had a long and interesting history. From the primitive Hyrochinus of the Eocene, in which it is dimly foreshadowed, we pass to a large and varied family in the later periods. In the Oligocene it spreads into three great branches, adapted, respectively, to life on the elevated lands, the lowlands, and the water. The upland type (Hyracodon) was a light-limbed running animal, well illustrating the close relation to the horse. The aquatic representative (Metamynodon) was a stumpy and bulky animal. The intermediate lowland type was probably the ancestor of the modern animal. All three forms were yet hornless. In the Miocene the lowland type (Leptaceratherium, Aceratherium, etc.) develops vigorously, while the other branches die. The European types now have two horns, and in one of the American species (Diceratherium) we see a commencement of the horny growths from the skull. We shall see later that the rhinoceros continued in Europe even during the severe conditions of the glacial period, in a branch that developed a woolly coat. There were also in the early Tertiary several sidebranches of the horse-tapir-rhinoceros family. The Palaeotheres were more or less between the horse and the tapir in structure; the Anoplotheres between the tapir and the ruminant. A third doomed branch, the Titanotheres, flourished vigorously for a time, and begot some strange and monstrous forms (Brontops, Titanops, etc.). In the larger specimens the body was about fourteen feet long, and stood ten feet from the ground. The long, low skull had a pair of horns over the snout. They perished like the equally powerful but equally sluggish and stupid Deinocerata. The Tertiary was an age of brain rather than of brawn. As compared with their early Tertiary representatives' some of our modern mammals have increased seven or eight-fold in brain-capacity. While the horses and tapirs and rhinoceroses were being gradually evolved from the primitive types, the Artiodactyl branch of the Ungulates--the pigs, deer, oxen, etc.--were also developing. We must dismiss them briefly. We saw that the primitive herbivores divided early in the Eocene into the "odd-toed" and "even-toed" varieties; the name refers, it will be remembered, not to the number of toes, but to the axis of stress. The Artiodactyl group must have quickly branched in turn, as we find very primitive hogs and camels before the end of the Eocene. The first hog-like creature (Homacodon) was much smaller than the hog of to-day, and had strong canine teeth, but in the Oligocene the family gave rise to a large and numerous race, the Elotheres. These "giant-pigs," as they have been called, with two toes on each foot, flourished vigorously for a time in Europe and America, but were extinguished in the Miocene, when the true pigs made their appearance. Another doomed race of the time is represented by the Hyopotamus, an animal between the pig and the hippopotamus; and the Oreodontids, between the hog and the deer, were another unsuccessful branch of the early race. The hippopotamus itself was widespread in Europe, and a familiar form in the rivers of Britain, in the latter part of the Tertiary. The camel seems to be traceable to a group of primitive North American Ungulates (Paebrotherium, etc.) in the later Eocene period. The Paebrotherium, a small animal about two feet long, is followed by Pliauchenia, which points toward the llamas and vicunas, and Procamelus, which clearly foreshadows the true camel. In the Pliocene the one branch went southward, to develop into the llamas and vicunas, and the other branch crossed to Asia, to develop into the camels. Since that time they have had no descendants in North America. The primitive giraffe appears suddenly in the later Tertiary deposits of Europe and Asia. The evidence points to an invasion from Africa, and, as the region of development is unknown and unexplored, the evolution of the giraffe remains a matter of speculation. Chevrotains flourished in Europe and North America in the Oligocene, and are still very primitive in structure, combining features of the hog and the ruminants. Primitive deer and oxen begin in the Miocene, and seem to have an earlier representative in certain American animals (Protoceras), of which the male has a pair of blunt outgrowths between the ears. The first true deer are hornless (like the primitive muskdeer of Asia to-day), but by the middle of the Miocene the males have small two-pronged antlers, and as the period proceeds three or four more prongs are added. It is some confirmation of the evolutionary embryonic law that we find the antlers developing in this way in the individual stag to-day. A very curious race of ruminants in the later Tertiary was a large antelope (Sivatherium) with four horns. It had not only the dimensions, but apparently some of the characters, of an elephant. The elephant itself, the last type of the Ungulates, has a clearer line of developments. A chance discovery of fossils in the Fayum district in Egypt led Dr. C. W. Andrews to make a special exploration, and on the remains which he found he has constructed a remarkable story of the evolution of the elephant. [*] It is clear that the elephant was developed in Africa, and a sufficiently complete series of remains has been found to give a good idea of the origin of its most distinctive features. In the Eocene period there lived in the Egyptian region an animal, something like the tapir in size and appearance, which had its second incisors developed into small tusks and--to judge from the nasal opening in the skull--a somewhat prolonged snout. This animal (Moeritherium) only differed from the ordinary primitive Ungulate in these incipient elephantine features. In the later Eocene a larger and more advanced animal, the Palaeomastodon, makes its appearance. Its tusks are larger (five or six inches long), its molars more elephantine, the air-cells at the back of the head more developed. It would look like a small elephant, except that it had a long snout, instead of a flexible trunk, and a projecting lower jaw on which the snout rested. *See this short account, "Guide to the Elephants in the British Museum," 1908. Up to the beginning of the Miocene, Africa was, as we saw, cut off from Europe and Asia by the sea which stretched from Spain to India. Then the land rose, and the elephant passed by the new tracts into the north. Its next representative, Tetrabelodon, is found in Asia and Europe, as well as North Africa. The frame is as large as that of a medium-sized elephant, and the increase of the air-cells at the back of the skull shows that an increased weight has to be sustained by the muscles of the neck. The nostrils are shifted further back. The tusks are from twenty to thirty inches long, and round, and only differ from those of the elephant in curving slightly downward, The chin projects as far as the tusks. The neck is shorter and thicker, and, as the animal increases in height, we can understand that the long snout--possibly prehensile at its lower end--is necessary for the animal to reach the ground. But the snout still lies on the projecting lower jaw, and is not a trunk. Passing over the many collateral branches, which diverge in various directions, we next kind that the chin is shortening (in Tetrabelodon longirostris), and, through a long series of discovered intermediate forms, we trace the evolution of the elephant from the mastodon. The long supporting skin disappears, and the enormous snout becomes a flexible trunk. Southern Asia seems to have been the province of this final transformation, and we have remains of some of these primitive elephants with tusks nine and a half feet long. A later species, which wandered over Central and Southern Europe before the close of the Tertiary, stood fifteen feet high at the shoulder, while the mammoth, which superseded it in the days of early man, had at times tusks more than ten feet in length. It is interesting to reflect that this light on the evolution of one of our most specialised mammals is due to the chance opening of the soil in an obscure African region. It suggests to us that as geological exploration is extended, many similar discoveries may be made. The slenderness of the geological record is a defect that the future may considerably modify. From this summary review of the evolution of the Ungulates we must now pass to an even briefer account of the evolution of the Carnivores. The evidence is less abundant, but the characters of the Carnivores consist so obviously of adaptations to their habits and diet that we have little difficulty in imagining their evolution. Their early Eocene ancestors, the Creodonts, gave rise in the Eocene to forms which we may regard as the forerunners of the cat-family and dog-family, to which most of our familiar Carnivores belong. Patriofelis, the "patriarchal cat," about five or six feet in length (without the tail), curiously combines the features of the cat and the seal-family. Cyonodon has a wolf-like appearance, and Amphicyon rather suggests the fox. Primitive weasels, civets, and hyaenas appear also in the Eocene. The various branches of the Carnivore family are already roughly represented, but it is an age of close relationships and generalised characters. In the Miocene we find the various groups diverging still further from each other and from the extinct stocks. Definite wolves and foxes abound in America, and the bear, civet, and hyaena are represented in Europe, together with vague otter-like forms. The dog-family seems to have developed chiefly in North America. As in the case of the Ungulates, we find many strange side-branches which flourished for a time, but are unknown to-day. Machoerodus, usually known as "the sabre-toothed tiger," though not a tiger, was one of the most formidable of these transitory races. Its upper canine teeth (the "sabres") were several inches in length, and it had enormously distensible jaws to make them effective. The great development of such animals, with large numbers of hyaenas, civets, wolves, bears, and other Carnivores, in the middle and later Tertiary was probably the most effective agency in the evolution of the horse and deer and the extinction of the more sluggish races. The aquatic branch of the Carnivores (seals, walruses, etc.) is little represented in the Tertiary record. We saw, however, that the most primitive representatives of the elephant-stock had also some characters of the seal, and it is thought that the two had a common origin. The Moeritherium was a marsh-animal, and may very well have been cousin to the branch of the family which pushed on to the seas, and developed its fore limbs into paddles. The Rodents are represented in primitive form early in the Eocene period. The teeth are just beginning to show the characteristic modification for gnawing. A large branch of the family, the Tillodonts, attained some importance a little later. They are described as combining the head and claws of a bear with the teeth of a rodent and the general characters of an ungulate. In the Oligocene we find primitive squirrels, beavers, rabbits, and mice. The Insectivores also developed some of the present types at an early date, and have since proved so unprogressive that some regard them as the stock from which all the placental mammals have arisen. The Cetacea (whales, porpoises, etc.) are already represented in the Eocene by a primitive whale-like animal (Zeuglodon) of unknown origin. Some specimens of it are seventy feet in length. It has large teeth, sometimes six inches long, and is clearly a terrestrial mammal that has returned to the waters. Some forms even of the modern whale develop rudimentary teeth, and in all forms the bony structure of the fore limbs and degenerate relic of a pelvis and back limbs plainly tell of the terrestrial origin. Dolphins appear in the Miocene. Finally, the Edentates (sloths, anteaters, and armadilloes) are represented in a very primitive form in the early Eocene. They are then barely distinguishable from the Condylarthra and Creodonta, and seem only recently to have issued from a common ancestor with those groups. In the course of the Tertiary we find them--especially in South America, which was cut off from the North and its invading Carnivores during the Eocene and Miocene--developed into large sloths, armadilloes, and anteaters. The reconnection with North America in the Pliocene allowed the northern animals to descend, but gigantic sloths (Megatherium) and armadilloes (Glyptodon) flourished long afterwards in South America. The Megatherium attained a length of eighteen feet in one specimen discovered, and the Glyptodon often had a dorsal shield (like that of the armadillo) from six to eight feet long, and, in addition, a stoutly armoured tail several feet long. The richness and rapidity of the mammalian development in the Tertiary, of which this condensed survey will convey some impression, make it impossible to do more here than glance over the vast field and indicate the better-known connections. It will be seen that evolution not only introduces a lucid order and arrangement into our thousands of species of living and fossil mammals, but throws an admirable light on the higher animal world of our time. The various orders into which the zoologist puts our mammals are seen to be the branches of a living tree, approaching more and more closely to each other in early Tertiary times, in spite of the imperfectness of the geological record. We at last trace these diverging lines to a few very primitive, generalised, patriarchal groups, which in turn approach each other very closely in structure, and plainly suggest a common Cretaceous ancestor. Whether that common ancestor was an Edentate, an Insectivore, or Creodont, or something more primitive than them all, is disputed. But the divergence of nearly all the lines of our mammal world from those patriarchal types is admirably clear. In the mutual struggle of carnivore and herbivore, in adaptation to a hundred different environments (the water, the land, and the air, the tree, the open plain, the underground, the marsh, etc.) and forms of diet, we find the descendants of these patriarchal animals gradually developing their distinctive characters. Then we find the destructive agencies of living and inorganic nature blotting out type after type, and the living things that spread over the land in the later Tertiary are found to be broadly identical with the living things of to-day. The last great selection, the northern Ice-Age, will give the last touches of modernisation. CHAPTER XVIII. THE EVOLUTION OF MAN We have reserved for a closer inquiry that order of the placental mammals to which we ourselves belong, and on which zoologists have bestowed the very proper and distinguishing name of the Primates. Since the days of Darwin there has been some tendency to resent the term "lower animals," which man applies to his poorer relations. But, though there is no such thing as an absolute standard by which we may judge the "higher" or "lower" status of animals or plants, the extraordinary power which man has by his brain development attained over both animate and inanimate nature fully justifies the phrase. The Primate order is, therefore, of supreme interest as the family that gave birth to man, and it is important to discover the agencies which impelled some primitive member of it to enter upon the path which led to this summit of organic nature. The order includes the femurs, a large and primitive family with ape-like features--the Germans call them "half-apes"--the monkeys, the man-like apes, and man. This classification according to structure corresponds with the successive appearance of the various families in the geological record. The femurs appear in the Eocene; the monkeys, and afterwards the apes, in the Miocene, the first semi-human forms in the Pleistocene, though they must have been developed before this. It is hardly necessary to say that science does not regard man as a descendant of the known anthropoid apes, or these as descended from the monkeys. They are successive types or phases of development, diverging early from each other. Just as the succeeding horse-types of the record are not necessarily related to each other in a direct line, yet illustrate the evolution of a type which culminates in the horse, so the spreading and branching members of the Primate group illustrate the evolution of a type of organism which culminates in man. The particular relationship of the various families, living and dead, will need careful study. That there is a general blood-relationship, and that man is much more closely related to the anthropoid apes than to any of the lower Primates, is no longer a matter of controversy. In Rudolph Virchow there died, a few years ago, the last authoritative man of science to express any doubt about it. There are, however, non-scientific writers who, by repeating the ambiguous phrase that it is "only a theory," convey the impression to inexpert readers that it is still more or less an open question. We will therefore indicate a few of the lines of evidence which have overcome the last hesitations of scientific men, and closed the discussion as to the fact. The very close analogy of structure between man and the ape at once suggests that they had a common ancestor. There are cases in which two widely removed animals may develop a similar organ independently, but there is assuredly no possibility of their being alike in all organs, unless by common inheritance. Yet the essential identity of structure in man and the ape is only confirmed by every advance of science, and would of itself prove the common parentage. Such minor differences as there are between man and the higher ape--in the development of the cerebrum, the number of the teeth or ribs, the distribution of the hair, and so on--are quite explicable when we reflect that the two groups must have diverged from each other more than a million years ago. Examining the structure of man more closely, we find this strong suggestion of relationship greatly confirmed. It is now well known that the human body contains a number of vestigial "organs"--organs of no actual use, and only intelligible as vestiges of organs that were once useful. Whatever view we take of the origin of man, each organ in his frame must have a meaning; and, as these organs are vestigial and useless even in the lowest tribes of men, who represent primitive man, they must be vestiges of organs that were of use in a remote pre-human ancestor. The one fact that the ape has the same vestigial organs as man would, on a scientific standard of evidence, prove the common descent of the two. But these interesting organs themselves point back far earlier than a mixed ape-human ancestor in many cases. The shell of cartilage which covers the entrance to the ear--the gristly appendage which is popularly called the ear--is one of the clearest and most easily recognised of these organs. The "ear" of a horse or a cat is an upright mobile shell for catching the waves of sound. The human ear has the appearance of being the shrunken relic of such an organ, and, when we remove the skin, and find seven generally useless muscles attached to it, obviously intended to pull the shell in all directions (as in the horse), there can be no doubt that the external ear is a discarded organ, a useless legacy from an earlier ancestor. In cases where it has been cut off it was found that the sense of hearing was scarcely, if at all, affected. Now we know that it is similarly useless in all tribes of men, and must therefore come from a pre-human ancestor. It is also vestigial in the higher apes, and it is only when we descend to the lower monkeys and femurs that we see it approaching its primitive useful form. One may almost say that it is a reminiscence of the far-off period when, probably in the early Tertiary, the ancestors of the Primates took to the trees. The animals living on the plain needed acute senses to detect the approach of their prey or their enemies; the tree-dweller found less demand on his sense of hearing, the "speaking-trumpet" was discarded, and the development of the internal ear proceeded on the higher line of the perception of musical sounds. We might take a very large number of parts of the actual human body, and discover that they are similar historical or archaeological monuments surviving in a modern system, but we have space only for a few of the more conspicuous. The hair on the body is a vestigial organ, of actual use to no race of men, an evident relic of the thick warm coat of an earlier ancestor. It in turn recalls the dwellers in the primeval forest. In most cases--not all, because the wearing of clothes for ages has modified this feature--it will be found that the hairs on the arm tend upward from the wrist to the elbow, and downward from the shoulder to the elbow. This very peculiar feature becomes intelligible when we find that some of the apes also have it, and that it has a certain use in their case. They put their hands over their heads as they sit in the trees during ram, and in that position the sloping hair acts somewhat like the thatched roof of a cottage. Again, it will be found that in the natural position of standing we are not perfectly flat-footed, but tend to press much more on the outer than on the inner edge of the foot. This tendency, surviving after ages of living on the level ground, is a lingering effect of the far-off arboreal days. A more curious reminiscence is seen in the fact that the very young infant, flabby and powerless as it is in most of its muscles, is so strong in the muscles of the hand and arm that it can hang on to a stick by its hands, and sustain the whole weight of its body, for several minutes. Finally, our vestigial tail--for we have a tail comparable to that of the higher apes--must be mentioned. In embryonic development the tail is much longer than the legs, and some children are born with a real tail, which they move as the puppy does, according to their emotional condition. Other features of the body point back to an even earlier stage. The vermiform appendage--in which some recent medical writers have vainly endeavoured to find a utility--is the shrunken remainder of a large and normal intestine of a remote ancestor. This interpretation of it would stand even if it were found to have a certain use in the human body. Vestigial organs are sometimes pressed into a secondary use when their original function has been lost. The danger of this appendage in the human body to-day is due to the fact that it is a blind alley leading off the alimentary canal, and has a very narrow opening. In the ape the opening is larger, and, significantly enough, it is still larger in the human foetus. When we examine some of the lower mammals we discover the meaning of it. It is in them an additional storage chamber in the alimentary system. It is believed that a change to a more digestible diet has made this additional chamber superfluous in the Primates, and the system is slowly suppressing it. Other reminiscences of this earlier phase are found in the many vestigial muscles which are found in the body to-day. The head of the quadruped hangs forward, and is held by powerful muscles and ligaments in the neck. We still have the shrunken remainder of this arrangement. Other vestigial muscles are found in the forehead, the scalp, the nose--many people can twitch the nostrils and the scalp--and under the skin in many parts of the body. These are enfeebled remnants of the muscular coat by which the quadruped twitches its skin, and drives insects away. A less obvious feature is found by the anatomist in certain blood-vessels of the trunk. As the blood flows vertically in a biped and horizontally in a quadruped, the arrangement of the valves in the blood-vessels should be different in the two cases; but it is the same in us as in the quadruped. Another trace of the quadruped ancestor is found in the baby. It walks "on all fours" so long, not merely from weakness of the limbs, but because it has the spine of a quadruped. A much more interesting fact, but one less easy to interpret, is that the human male has, like the male ape, organs for suckling the young. That there are real milk-glands, usually vestigial, underneath the teats in the breast of the boy or the man is proved by the many known cases in which men have suckled the young. Several friends of the present writer have seen this done in India and Ceylon by male "wet-nurses." As there is no tribe of men or species of ape in which the male suckles the young normally, we seem to be thrown back once more upon an earlier ancestor. The difficulty is that we know of no mammal of which both parents suckle the young, and some authorities think that the breasts have been transferred to the male by a kind of embryonic muddle. That is difficult to believe, as no other feature has ever been similarly transferred to the opposite sex. In any case the male breasts are vestigial organs. Another peculiarity of the mammary system is that sometimes three, four, or five pairs of breasts appear in a woman (and several have been known even in a man). This is, apparently, an occasional reminiscence of an early mammal ancestor which had large litters of young and several pairs of breasts. But there are features of the human body which recall an ancestor even earlier than the quadruped. The most conspicuous of these is the little fleshy pad at the inner corner of each eye. It is a common feature in mammals, and is always useless. When, however, we look lower down in the animal scale we find that fishes and reptiles (and birds) have a third eyelid, which is drawn across the eye from this corner. There is little room to doubt that the little fleshy vestige in the mammal's eye is the shrunken remainder of the lateral eyelid of a remote fish-ancestor. A similar reminiscence is found in the pineal body, a small and useless object, about the size and shape of a hazel-nut, in the centre of the brain. When we examine the reptile we find a third eye in the top of the head. The skin has closed over it, but the skull is still, in many cases, perforated as it is for the eyes in front. I have seen it standing out like a ball on the head of a dead crocodile, and in the living tuatara--the very primitive New Zealand lizard--it still has a retina and optic nerve. As the only animal in nature to-day with an eye in this position (the Pyrosome, a little marine animal of the sea-squirt family) is not in the line of reptile and mammal ancestry, it is difficult to locate the third eye definitely. But when we find the skin closing over it in the amphibian and reptile, then the bone, and then see it gradually atrophying and being buried under the growing brain, we must refer it to some early fish-ancestor. This ancestor, we may recall, is also reflected for a time in the gill-slits and arches, with their corresponding fish-like heart and blood-vessels, during man's embryonic development, as we saw in a former chapter. These are only a few of the more conspicuous instances of vestigial structures in man. Metchnikoff describes about a hundred of them. Even if there were no remains of primitive man pointing in the direction of a common ancestry with the ape, no lower types of men in existence with the same tendency, no apes found in nature to-day with a structure so strikingly similar to that of man, and no fossil records telling of the divergence of forms from primitive groups in past time, we should be forced to postulate the evolution of man in order to explain his actual features. The vestigial structures must be interpreted as we interpret the buttons on the back of a man's coat. They are useless reminiscences of an age in which they were useful. When their witness to the past is supported by so many converging lines of evidence it becomes irresistible. I will add only one further testimony which has been brought into court in recent years. The blood consists of cells, or minute disk-shaped corpuscles, floating in a watery fluid, or serum. It was found a few years ago, in the course of certain experiments in mixing the blood of animals, that the serum of one animal's blood sometimes destroyed the cells of the other animal's blood, and at other times did not. When the experiments were multiplied, it was found that the amount of destructive action exercised by one specimen of blood upon another depended on the nearness or remoteness of relationship between the animals. If the two are closely related, there is no disturbance when their blood is mixed; when they are not closely related, the serum of one destroys the cells of the other, and the intensity of the action is in proportion to their remoteness from each other. Another and more elaborate form of the experiment was devised, and the law was confirmed. On both tests it was found by experiment that the blood of man and of the anthropoid ape behaved in such a way as to prove that they were closely related. The blood of the monkey showed a less close relationship--a little more remote in the New World than in the Old World monkeys; and the blood of the femur showed a faint and distant relationship. The FACT of the evolution of man and the apes from a common ancestor is, therefore, outside the range of controversy in science; we are concerned only to retrace the stages of that evolution, and the agencies which controlled it. Here, unfortunately, the geological record gives us little aid. Tree-dwelling animals are amongst the least likely to be buried in deposits which may preserve their bones for ages. The distribution of femur and ape remains shows that the order of the Primates has been widespread and numerous since the middle of the Tertiary Era, yet singularly few remains of the various families have been preserved. Hence the origin of the Primates is obscure. They are first foreshadowed in certain femur-like forms of the Eocene period, which are said in some cases (Adapis) to combine the characters of pachyderms and femurs, and in others (Anaptomorphus) to unite the features of Insectivores and femurs. Perhaps the more common opinion is that they were evolved from a branch of the Insectivores, but the evidence is too slender to justify an opinion. It was an age when the primitive placental mammals were just beginning to diverge from each other, and had still many features in common. For the present all we can say is that in the earliest spread of the patriarchal mammal race one branch adopted arboreal life, and evolved in the direction of the femurs and the apes. The generally arboreal character of the Primates justifies this conclusion. In the Miocene period we find a great expansion of the monkeys. These in turn enter the scene quite suddenly, and the authorities are reduced to uncertain and contradictory conjectures as to their origin. Some think that they develop not from the femurs, but along an independent line from the Insectivores, or other ancestors of the Primates. We will not linger over these early monkeys, nor engage upon the hopeless task of tracing their gradual ramification into the numerous families of the present age. It is clear only that they soon divided into two main streams, one of which spread into the monkeys of America and the other into the monkeys of the Old World. There are important anatomical differences between the two. The monkeys remained in Central and Southern Europe until near the end of the Tertiary. Gradually we perceive that the advancing cold is driving them further south, and the monkeys of Gibraltar to-day are the diminished remnant of the great family that had previously wandered as far as Britain and France. A third wave, also spreading in the Miocene, equally obscure in its connection with the preceding, introduces the man-like apes to the geologist. Primitive gibbons (Pliopithecus and Pliobylobates), primitive chimpanzees (Palaeopithecus), and other early anthropoid apes (Oreopithecus, Dryopithecus, etc.), lived in the trees of Southern Europe in the second part of the Tertiary Era. They are clearly disconnected individuals of a large and flourishing family, but from the half-dozen specimens we have yet discovered no conclusion can be drawn, except that the family is already branching into the types of anthropoid apes which are familiar to us. Of man himself we have no certain and indisputable trace in the Tertiary Era. Some remains found in Java of an ape-man (Pithecanthropus), which we will study later, are now generally believed, after a special investigation on the spot, to belong to the Pleistocene period. Yet no authority on the subject doubts that the human species was evolved in the Tertiary Era, and very many, if not most, of the authorities believe that we have definite proof of his presence. The early story of mankind is gathered, not so much from the few fragments of human remains we have, but from the stone implements which were shaped by his primitive intelligence and remain, almost imperishable, in the soil over which he wandered. The more primitive man was, the more ambiguous would be the traces of his shaping of these stone implements, and the earliest specimens are bound to be a matter of controversy. It is claimed by many distinguished authorities that flints slightly touched by the hand of man, or at least used as implements by man, are found in abundance in England, France, and Germany, and belong to the Pliocene period. Continental authorities even refer some of them to the Miocene and the last part of the Oligocene. The question whether an implement-using animal, which nearly all would agree to regard as in some degree human, wandered over what is now the South of England (Kent, Essex, Dorsetshire, etc.) as many hundred thousand years ago as this claim would imply, is certainly one of great interest. But there would be little use in discussing here the question of the "Eoliths," as these disputed implements are called. A very keen controversy is still being conducted in regard to them, and some of the highest authorities in England, France, and Germany deny that they show any trace of human workmanship or usage. Although they have the support of such high authorities as Sir J. Prestwich, Sir E. Ray Lankester, Lord Avebury, Dr. Keane, Dr. Blackmore, Professor Schwartz, etc., they are one of those controverted testimonies on which it would be ill-advised to rely in such a work as this. We must say, then, that we have no undisputed traces of man in the Tertiary Era. The Tertiary implements which have been at various times claimed in France, Italy, and Portugal are equally disputed; the remains which were some years ago claimed as Tertiary in the United States are generally disallowed; and the recent claims from South America are under discussion. Yet it is the general feeling of anthropologists that man was evolved in the Tertiary Era. On the one hand, the anthropoid apes were highly developed by the Miocene period, and it would be almost incredible that the future human stock should linger hundreds of thousands of years behind them. On the other hand, when we find the first traces of man in the Pleistocene, this development has already proceeded so far that its earlier phase evidently goes back into the Tertiary. Let us pass beyond the Tertiary Era for a moment, and examine the earliest and most primitive remains we have of human or semi-human beings. The first appearance of man in the chronicle of terrestrial life is a matter of great importance and interest. Even the least scientific of readers stands, so to say, on tiptoe to catch a first glimpse of the earliest known representative of our race, and half a century of discussion of evolution has engendered a very wide interest in the early history of man. [*] * A personal experience may not be without interest in this connection. Among the many inquiries directed to me in regard to evolution I received, in one month, a letter from a negro in British Guiana and an extremely sensible query from an inmate of an English asylum for the insane! The problem that beset the latter of the two was whether the Lemuranda preceded the Lemurogona in Eocene times. He had found a contradiction in the statements of two scientific writers. Fortunately, although these patriarchal bones are very scanty--two teeth, a thigh-bone, and the skull-cap--we are now in a position to form some idea of the nature of their living owner. They have been subjected to so searching a scrutiny and discussion since they were found in Java in 1891 and 1892 that there is now a general agreement as to their nature. At first some of the experts thought that they were the remains of an abnormally low man, and others that they belonged to an abnormally high ape. The majority held from the start that they belonged to a member of a race almost midway between the highest family of apes and the lowest known tribe of men, and therefore fully merited the name of "Ape-Man" (Pithecanthropus). This is now the general view of anthropologists. The Ape-Man of Java was in every respect entitled to that name. The teeth suggest a lower part of the face in which the teeth and lips projected more than in the most ape-like types of Central Africa. The skull-cap has very heavy ridges over the eyes and a low receding forehead, far less human than in any previously known prehistoric skull. The thigh-bone is very much heavier than any known human femur of the same length, and so appreciably curved that the owner was evidently in a condition of transition from the semi-quadrupedal crouch of the ape to the erect attitude of man. The Ape-Man, in other words, was a heavy, squat, powerful, bestial-looking animal; of small stature, but above the pygmy standard; erect in posture, but with clear traces of the proneness of his ancestor; far removed from the highest ape in brainpower, but almost equally far removed from the lowest savage that is known to us. We shall see later that there is some recent criticism, by weighty authorities, of the earlier statements in regard to the brain of primitive man. This does not apply to the Ape-Man of Java. The average cranial capacity (the amount of brain-matter the skull may contain) of the chimpanzees, the highest apes, is about 600 cubic centimetres. The average cranial capacity of the lowest races of men, of moderate stature, is about 1200. And the cranial capacity of Ape-Man was about 900 It is immaterial whether or no these bones belong to the same individual. If they do not, we have remains of two or three individuals of the same intermediate species. Nor does it matter whether or no this early race is a direct ancestor of the later races of men, or an extinct offshoot from the advancing human stock. It is, in either case, an illustration of the intermediate phase between the ape and man The more important tasks are to trace the relationship of this early human stock to the apes, and to discover the causes of its superior evolution. The first question has a predominantly technical interest, and the authorities are not agreed in replying to it. We saw that, on the blood-test, man showed a very close relationship to the anthropoid apes, a less close affinity to the Old World monkeys, a more remote affinity to the American monkeys, and a very faint and distant affinity to the femurs. A comparison of their structures suggests the same conclusion. It is, therefore, generally believed that the anthropoid apes and man had a common ancestor in the early Miocene or Oligocene, that this group was closely related to the ancestral group of the Old World monkeys, and that all originally sprang from a primitive and generalised femur-group. In other words, a branch of the earliest femur-like forms diverges, before the specific femur-characters are fixed, in the direction of the monkey; in this still vague and patriarchal group a branch diverges, before the monkey-features are fixed, in the direction of the anthropoids; and this group in turn spreads into a number of types, some of which are the extinct apes of the Miocene, four become the gorilla, chimpanzee, orang, and gibbon of to-day, and one is the group that will become man. To put it still more precisely, if we found a whole series of remains of man's ancestors during the Tertiary, we should probably class them, broadly, as femur-remains in the Eocene, monkey-remains in the Oligocene, and ape-remains in the Miocene. In that sense only man "descends from a monkey." The far more important question is: How did this one particular group of anthropoid animals of the Miocene come to surpass all its cousins, and all the rest of the mammals, in brain-development? Let us first rid the question of its supposed elements of mystery and make of it a simple problem. Some imagine that a sudden and mysterious rise in intelligence lifted the progenitor of man above its fellows. The facts very quickly dispel this illusion. We may at least assume that the ancestor of man was on a level with the anthropoid ape in the Miocene period, and we know from their skulls that the apes were as advanced then as they are now. But from the early Miocene to the Pleistocene is a stretch of about a million years on the very lowest estimate. In other words, man occupied about a million years in travelling from the level of the chimpanzee to a level below that of the crudest savage ever discovered. If we set aside the Java man, as a possible survivor of an earlier phase, we should still have to say that, much more than a million years after his departure from the chimpanzee level, man had merely advanced far enough to chip stone implements; because we find no other trace whatever of intelligence than this until near the close of the Palaeolithic period. If there is any mystery, it is in the slowness of man's development. Let us further recollect that it is a common occurrence in the calendar of life for a particular organ to be especially developed in one member of a particular group more than in the others. The trunk of the elephant, the neck of the giraffe, the limbs of the horse or deer, the canines of the satire-toothed tiger, the wings of the bat, the colouring of the tiger, the horns of the deer, are so many examples in the mammal world alone. The brain is a useful organ like any other, and it is easy to conceive that the circumstances of one group may select it just as the environment of another group may lead to the selection of speed, weapons, or colouring. In fact, as we saw, there was so great and general an evolution of brain in the Tertiary Era that our modern mammals quite commonly have many times the brain of their Tertiary ancestors. Can we suggest any reasons why brain should be especially developed in the apes, and more particularly still in the ancestors of man? The Primate group generally is a race of tree-climbers. The appearance of fruit on early Tertiary trees and the multiplication of carnivores explain this. The Primate is, except in a few robust cases, a particularly defenceless animal. When its earliest ancestors came in contact with fruit and nut-bearing trees, they developed climbing power and other means of defence and offense were sacrificed. Keenness of scent and range of hearing would now be of less moment, but sight would be stimulated, especially when soft-footed climbing carnivores came on the scene. There is, however, a much deeper significance in the adoption of climbing, and we must borrow a page from the modern physiology of the brain to understand it. The stress laid in the modern education of young children on the use of the hands is not merely due to a feeling that they should handle objects as well as read about them. It is partly due to the belief of many distinguished physiologists that the training of the hands has a direct stimulating effect on the thought-centres in the brain. The centre in the cerebrum which controls the use of the hands is on the fringe of the region which seems to be concerned in mental operations. For reasons which will appear presently, we may add that the centres for controlling the muscles of the face and head are in the same region. Any finer training or the use of the hands will develop the centre for the fore limbs, and, on the principles, may react on the more important region of the cortex. Hence in turning the fore foot into a hand, for climbing and grasping purposes, the primitive Primate entered upon the path of brain-development. Even the earliest Primates show large brains in comparison with the small brains of their contemporaries. It is a familiar fact in the animal world that when a certain group enters upon a particular path of evolution, some members of the group advance only a little way along it, some go farther, and some outstrip all the others. The development of social life among the bees will illustrate this. Hence we need not be puzzled by the fact that the lemurs have remained at one mental level, the monkeys at another, and the apes at a third. It is the common experience of life; and it is especially clear among the various races of men. A group becomes fitted to its environment, and, as long as its surroundings do not change, it does not advance. A related group, in a different environment, receives a particular stimulation, and advances. If, moreover, a group remains unstimulated for ages, it may become so rigid in its type that it loses the capacity to advance. It is generally believed that the lowest races of men, and even some of the higher races like the Australian aboriginals, are in this condition. We may expect this "unteachability" in a far more stubborn degree in the anthropoid apes, which have been adapted to an unchanging environment for a million years. All that we need further suppose is--and it is one of the commonest episodes in terrestrial life--that one branch of the Miocene anthropoids, which were spread over a large part of the earth, received some stimulus to change which its cousins did not experience. It is sometimes suggested that social life was the great advantage which led to the superior development of mind in man. But such evidence as there is would lead us to suppose that primitive man was solitary, not social. The anthropoid apes are not social, but live in families, and are very unprogressive. On the other hand, the earliest remains of prehistoric man give no indication of social life. Fire-places, workshops, caves, etc., enter the story in a later phase. Some authorities on prehistoric man hold very strongly that during the greater part of the Old Stone Age (two-thirds, at least, of the human period) man wandered only in the company of his mate and children. [*] * The point will be more fully discussed later. This account of prehistoric life is well seen in Mortillet's Prehistorique (1900). The lowest races also have no tribal life, and Professor Westermarck is of opinion that early man was not social. We seem to have the most plausible explanation of the divergence of man from his anthropoid cousins in the fact that he left the trees of his and their ancestors. This theory has the advantage of being a fact--for the Ape-Man race of Java has already left the trees--and providing a strong ground for brain-advance. A dozen reasons might be imagined for his quitting the trees--migration, for instance, to a region in which food was more abundant, and carnivores less formidable, on the ground-level--but we will be content with the fact that he did. Such a change would lead to a more consistent adoption of the upright attitude, which is partly found in the anthropoid apes, especially the gibbons. The fore limb would be no longer a support of the body; the hand would be used more for grasping; and the hand-centre in the brain would be proportionately stimulated. The adoption of the erect attitude would further lead to a special development of the muscles of the head and face, the centre for which is in the same important region in the cortex. There would also be a direct stimulation of the brain, as, having neither weapons nor speed, the animal would rely all the more on sight and mind. If we further suppose that this primitive being extended the range of his hunting, from insects and small or dead birds to small land-animals, the stimulation would be all the greater. In a word, the very fact of a change from the trees to the ground suggests a line of brain-development which may plausibly be conceived, in the course of a million years, to evolve an Ape-Man out of a man-like ape. And we are not introducing any imaginary factor in this view of human origins. The problem of the evolution of man is often approached in a frame of mind not far removed from that of the educated, but inexpert, European who stands before the lowly figure of the chimpanzee, and wonders by what miracle the gulf between it and himself was bridged. That is to lay a superfluous strain on the imagination. The proper term of comparison is the lowest type of human being known to us, since the higher types of living men have confessedly evolved from the lower. But even the lowest type of existing or recent savage is not the lowest level of humanity. Whether or no the Tasmanian or the Yahgan is a primitive remnant of the Old Stone Age, we have a far lower depth in the Java race. What we have first to do is to explain the advance to that level, in the course of many hundreds of thousands of years: a period fully a hundred times as long as the whole history of civilisation. Time itself is no factor in evolution, but in this case it is a significant condition. It means that, on this view of the evolution of man, we are merely assuming that an advance in brain-development took place between the Miocene and the Pleistocene, not similar to, but immeasurably less than, the advance which we know to have been made in the last fifty thousand years. In point of fact, the most mysterious feature of the evolution of man was its slowness. We shall see that, to meet the facts, we must suppose man to have made little or no progress during most of this vast period, and then to have received some new stimulation to develop. What it was we have now to inquire. CHAPTER XIX. MAN AND THE GREAT ICE-AGE In discussing the development of plants and animals during the Tertiary Era we have already perceived the shadow of the approaching Ice-Age. We found that in the course of the Tertiary the types which were more sensitive to cold gradually receded southward, and before its close Europe, Asia, and North America presented a distinctly temperate aspect. This is but the penumbra of the eclipse. When we pass the limits of the Tertiary Era, and enter the Quaternary, the refrigeration steadily proceeds, and, from temperate, the aspect of much of Europe and North America becomes arctic. From six to eight million square miles of the northern hemisphere are buried under fields of snow and ice, and even in the southern regions smaller glacial sheets spread from the foot of the higher ranges of mountains. It is unnecessary to-day to explain at any length the evidences by which geologists trace this enormous glaciation of the northern hemisphere. There are a few works still in circulation in which popular writers, relying on the obstinacy of a few older geologists, speak lightly of the "nightmare" of the Ice-Age. But the age has gone by in which it could seriously be suggested that the boulders strewn along the east of Scotland--fragments of rock whose home we must seek in Scandinavia--were brought by the vikings as ballast for their ships. Even the more serious controversy, whether the scratches and the boulders which we find on the face of Northern Europe and America were due to floating or land ice, is virtually settled. Several decades of research have detected the unmistakable signs of glacial action over this vast area of the northern hemisphere. Most of Europe north of the Thames and the Danube, nearly all Canada and a very large part of the United States, and a somewhat less expanse of Northern Asia, bear to this day the deep scars of the thick, moving ice-sheets. Exposed rock-surfaces are ground and scratched, beds of pebbles are twisted and contorted hollows are scooped out, and moraines--the rubbish-heaps of the glaciers--are found on every side. There is now not the least doubt that, where the great Deinosaurs had floundered in semi-tropical swamps, where the figs and magnolias had later flourished, where the most industrious and prosperous hives of men are found to-day, there was, in the Pleistocene period, a country to which no parallel can be found outside the polar circles to-day. The great revolution begins with the gathering of snows on the mountains. The Alps and Pyrenees had now, we saw, reached their full stature, and the gathering snows on their summits began to glide down toward the plains in rivers of ice. The Apennines (and even the mountains of Corsica), the Balkans, Carpathians, Caucasus, and Ural Mountains, shone in similar mantles of ice and snow. The mountains of Wales, the north of England, Scotland, and Scandinavia had even heavier burdens, and, as the period advanced, their sluggish streams of ice poured slowly over the plains. The trees struggled against the increasing cold in the narrowing tracts of green; the animals died, migrated to the south, or put on arctic coats. At length the ice-sheets of Scandinavia met the spreading sheets from Scotland and Wales, and crept over Russia and Germany, and an almost continuous mantle, from which only a few large areas of arctic vegetation peeped out, was thrown over the greater part of Europe. Ten thousand feet thick where it left the hills of Norway and Sweden, several thousand feet thick even in Scotland, the ice-sheet that resulted from the fusion of the glaciers gradually thinned as it went south, and ended in an irregular fringe across Central Europe. The continent at that time stretched westward beyond the Hebrides and some two hundred miles beyond Ireland. The ice-front followed this curve, casting icebergs into the Atlantic, then probably advanced up what is now the Bristol Channel, and ran across England and Europe, in a broken line, from Bristol to Poland. South of this line there were smaller ice-fields round the higher mountains, north of it almost the whole country presented the appearance that we find in Greenland to-day. In North America the glaciation was even more extensive. About four million square miles of the present temperate zone were buried under ice and snow. From Greenland, Labrador, and the higher Canadian mountains the glaciers poured south, until, in the east, the mass of ice penetrated as far as the valley of the Mississippi. The great lakes of North America are permanent memorials of its Ice-Age, and over more than half the country we trace the imprint and the relics of the sheet. South America, Australia, Tasmania, and New Zealand had their glaciated areas. North Asia was largely glaciated, but the range of the ice-sheet is not yet determined in that continent. This summary statement will convey some idea of the extraordinary phase through which the earth passed in the early part of the present geological era. But it must be added that a singular circumstance prolonged the glacial regime in the northern hemisphere. Modern geologists speak rather of a series of successive ice-sheets than of one definite Ice-Age. Some, indeed, speak of a series of Ice-Ages, but we need not discuss the verbal question. It is now beyond question that the ice-sheet advanced and retreated several times during the Glacial Epoch. The American and some English geologists distinguished six ice-sheets, with five intermediate periods of more temperate climate. The German and many English and French geologists distinguish four sheets and three interglacial epochs. The exact number does not concern us, but the repeated spread of the ice is a point of some importance. The various sheets differed considerably in extent. The wide range of the ice which I have described represents the greatest extension of the glaciation, and probably corresponds to the second or third of the six advances in Dr. Geikie's (and the American) classification. Before we consider the biological effect of this great of refrigeration of the globe, we must endeavour to understand the occurrence itself. Here we enter a world of controversy, but a few suggestions at least may be gathered from the large literature of the subject, which dispel much of the mystery of the Great Ice-Age. It was at one time customary to look out beyond the earth itself for the ultimate causes of this glaciation. Imagine the sheet of ice, which now spreads widely round the North Pole, shifted to another position on the surface of the planet, and you have a simple explanation of the occurrence. In other words, if we suppose that the axis of the earth does not consistently point in one direction--that the great ball does not always present the same average angle in relation to the sun--the poles will not always be where they are at present, and the Pleistocene Ice-Age may represent a time when the north pole was in the latitude of North Europe and North America. This opinion had to be abandoned. We have no trace whatever of such a constant shifting of the polar regions as it supposes, and, especially, we have no trace that the warm zone correspondingly shifted in the Pleistocene. A much more elaborate theory was advanced by Dr. Croll, and is still entertained by many. The path of the earth round the sun is not circular, but elliptical, and there are times when the gravitational pull of the other planets increases the eccentricity of the orbit. It was assumed that there are periods of great length, separated from each other by still longer periods, when this eccentricity of the orbit is greatly exaggerated. The effect would be to prolong the winter and shorten the summer of each hemisphere in turn. The total amount of heat received would not alter, but there would be a long winter with less heat per hour, and a short summer with more heat. The short summer would not suffice to melt the enormous winter accumulations of ice and snow, and an ice-age would result. To this theory, again, it is objected that we do not find the regular succession of ice-ages in the story of the earth which the theory demands, and that there is no evidence of an alternation of the ice between the northern and southern hemispheres. More recent writers have appealed to the sun itself, and supposed that some prolonged veiling of its photosphere greatly reduced the amount of heat emitted by it. More recently still it has been suggested that an accumulation of cosmic or meteoric dust in our atmosphere, or between us and the sun, had, for a prolonged period, the effect of a colossal "fire-screen." Neither of these suppositions would explain the localisation of the ice. In any case we need not have recourse to purely speculative accidents in the world beyond until it is clear that there were no changes in the earth itself which afford some explanation. This is by no means clear. Some writers appeal to changes in the ocean currents. It is certain that a change in the course of the cold and warm currents of the ocean to-day might cause very extensive changes of climate, but there seems to be some confusion of ideas in suggesting that this might have had an equal, or even greater, influence in former times. Our ocean currents differ so much in temperature because the earth is now divided into very pronounced zones of climate. These zones did not exist before the Pliocene period, and it is not at all clear that any redistribution of currents in earlier times could have had such remarkable consequences. The same difficulty applies to wind-currents. On the other hand, we have already, in discussing the Permian glaciation, discovered two agencies which are very effective in lowering the temperature of the earth. One is the rise of the land; the other is the thinning of the atmosphere. These are closely related agencies, and we found them acting in conjunction to bring about the Permian Ice-Age. Do we find them at work in the Pleistocene? It is not disputed that there was a very considerable upheaval of the land, especially in Europe and North America, at the end of the Tertiary Era. Every mountain chain advanced, and our Alps, Pyrenees, Himalaya, etc., attained, for the first time, their present, or an even greater elevation. The most critical geologists admit that Europe, as a whole, rose 4000 feet above its earlier level. Such an elevation would be bound to involve a great lowering of the temperature. The geniality of the Oligocene period was due, like that of the earlier warm periods, to the low-lying land and very extensive water-surface. These conditions were revolutionised before the end of the Tertiary. Great mountains towered into the snow-line, and vast areas were elevated which had formerly been sea or swamp. This rise of the land involved a great decrease in the proportion of moisture in the atmosphere. The sea surface was enormously lessened, and the mountains would now condense the moisture into snow or cloud to a vastly greater extent than had ever been known before There would also be a more active circulation of the atmosphere, the moist warm winds rushing upward towards the colder elevations and parting with their vapour. As the proportion of moisture in the atmosphere lessened the surface-heat would escape more freely into space, the general temperature would fall, and the evaporation--or production of moisture would be checked, while the condensation would continue. The prolonging of such conditions during a geological period can be understood to have caused the accumulation of fields of snow and ice in the higher regions. It seems further probable that these conditions would lead to a very considerable formation of fog and cloud, and under this protecting canopy the glaciers would creep further down toward the plains. We have then to consider the possibility of a reduction of the quantity of carbon-dioxide in the atmosphere The inexpert reader probably has a very exaggerated idea of the fall in temperature that would be required to give Europe an Ice-Age. If our average temperature fell about 5-8 degrees C. below the average temperature of our time it would suffice; and it is further calculated that if the quantity of carbon-dioxide in our atmosphere were reduced by half, we should have this required fall in temperature. So great a reduction would not be necessary in view of the other refrigerating agencies. Now it is quite certain that the proportion of carbon-dioxide was greatly reduced in the Pleistocene. The forests of the Tertiary Era would steadily reduce it, but the extensive upheaval of the land at its close would be even more important. The newly exposed surfaces would absorb great quantities of carbon. The ocean, also, as it became colder, would absorb larger and larger quantities of carbon-dioxide. Thus the Pleistocene atmosphere, gradually relieved of its vapours and carbon-dioxide, would no longer retain the heat at the surface. We may add that the growth of reflective surfaces--ice, snow, cloud, etc.--would further lessen the amount of heat received from the sun. Here, then, we have a series of closely related causes and effects which would go far toward explaining, if they do not wholly suffice to explain, the general fall of the earth's temperature. The basic cause is the upheaval of the land--a fact which is beyond controversy, the other agencies are very plain and recognisable consequences of the upheaval. There are, however, many geologists who do not think this explanation adequate. It is pointed out, in the first place, that the glaciation seems to have come long after the elevation. The difficulty does not seem to be insurmountable. The reduction of the atmospheric vapour would be a gradual process, beginning with the later part of the elevation and culminating long afterwards. The reduction of the carbon-dioxide would be even more gradual. It is impossible to say how long it would take these processes to reach a very effective stage, but it is equally impossible to show that the interval between the upheaval and the glaciation is greater than the theory demands. It is also said that we cannot on these principles understand the repeated advance and retreat of the ice-sheet. This objection, again, seems to fail. It is an established fact that the land sank very considerably during the Ice-Age, and has risen again since the ice disappeared. We find that the crust in places sank so low that an arctic ocean bathed the slopes of some of the Welsh mountains; and American geologists say that their land has risen in places from 2000 to 3000 feet (Chamberlin) since the burden of ice was lifted from it. Here we have the possibility of an explanation of the advances and retreats of the glaciers. The refrigerating agencies would proceed until an enormous burden of ice was laid on the land of the northern hemisphere. The land apparently sank under the burden, the ice and snow melted at the lower level and there was a temperate interglacial period. But the land, relieved of its burden, rose once more, the exposed surface absorbed further quantities of carbon, and a fresh period of refrigeration opened. This oscillation might continue until the two sets of opposing forces were adjusted, and the crust reached a condition of comparative stability. Finally, and this is the more serious difficulty, it is said that we cannot in this way explain the localisation of the glacial sheets. Why should Europe and North America in particular suffer so markedly from a general thinning of the atmosphere? The simplest answer is to suggest that they especially shared the rise of the land. Geology is not in a position either to prove or disprove this, and it remains only a speculative interpretation of the fact We know at least that there was a great uprise of land in Europe and North America in the Pliocene and Pleistocene and may leave the precise determination of the point to a later age. At the same time other local causes are not excluded. There may have been a large extension of the area of atmospheric depression which we have in the region of Greenland to-day. When we turn to the question of chronology we have the same acute difference of opinion as we have found in regard to all questions of geological time. It used to be urged, on astronomical grounds, that the Ice-Age began about 240,000 years ago, and ended about 60,000 years ago, but the astronomical theory is, as I said, generally abandoned. Geologists, on the other hand, find it difficult to give even approximate figures. Reviewing the various methods of calculation, Professor Chamberlin concludes that the time of the first spread of the ice-sheet is quite unknown, the second and greatest extension of the glaciation may have been between 300,000 and a million years ago, and the last ice-extension from 20,000 to 60,000 years ago; but he himself attaches "very little value" to the figures. The chief ice-age was some hundreds of thousands of years ago, that is all we can say with any confidence. In dismissing the question of climate, however, we should note that a very serious problem remains unsolved. As far as present evidence goes we seem to be free to hold that the ice-ages which have at long intervals invaded the chronicle of the earth were due to rises of the land. Upheaval is the one constant and clearly recognisable feature associated with, or preceding, ice-ages. We saw this in the case of the Cambrian, Permian, Eocene, and Pleistocene periods of cold, and may add that there are traces of a rise of mountains before the glaciation of which we find traces in the middle of the Archaean Era. There are problems still to be solved in connection with each of these very important ages, but in the rise of the land and consequent thinning of the atmosphere we seem to have a general clue to their occurrence. Apart from these special periods of cold, however, we have seen that there has been, in recent geological times, a progressive cooling of the earth, which we have not explained. Winter seems now to be a permanent feature of the earth's life, and polar caps are another recent, and apparently permanent, acquisition. I find no plausible reason assigned for this. The suggestion that the disk of the sun is appreciably smaller since Tertiary days is absurd; and the idea that the earth has only recently ceased to allow its internal heat to leak through the crust is hardly more plausible. The cause remains to be discovered. We turn now to consider the effect of the great Ice-Age, and the relation of man to it. The Permian revolution, to which the Pleistocene Ice-Age comes nearest in importance, wrought such devastation that the overwhelming majority of living things perished. Do we find a similar destruction of life, and selection of higher types, after the Pleistocene perturbation? In particular, had it any appreciable effect upon the human species? A full description of the effect of the great Ice-Age would occupy a volume. The modern landscape in Europe and North America was very largely carved and modelled by the ice-sheet and the floods that ensued upon its melting. Hills were rounded, valleys carved, lakes formed, gravels and soils distributed, as we find them to-day. In its vegetal aspect, also, as we saw, the modern landscape was determined by the Pleistocene revolution. A great scythe slowly passed over the land. When the ice and snow had ended, and the trees and flowers, crowded in the southern area, slowly spread once more over the virgin soil, it was only the temperate species that could pass the zone guarded by the Alps and the Pyrenees. On the Alps themselves the Pleistocene population still lingers, their successful adaptation to the cold now preventing them from descending to the plains. The animal world in turn was winnowed by the Pleistocene episode. The hippopotamus, crocodile, turtle, flamingo, and other warm-loving animals were banished to the warm zone. The mammoth and the rhinoceros met the cold by developing woolly coats, but the disappearance of the ice, which had tempted them to this departure, seems to have ended their fitness. Other animals which became adapted to the cold--arctic bears, foxes, seals, etc.--have retreated north with the ice, as the sheet melted. For hundreds of thousands of years Europe and North America, with their alternating glacial and interglacial periods, witnessed extraordinary changes and minglings of their animal population. At one time the reindeer, the mammoth, and the glutton penetrate down to the Mediterranean, in the next phase the elephant and hippopotamus again advance nearly to Central Europe. It is impossible here to attempt to unravel these successive changes and migrations. Great numbers of species were destroyed, and at length, when the climatic condition of the earth reached a state of comparative stability, the surviving animals settled in the geographical regions in which we find them to-day. The only question into which we may enter with any fullness is that of the relation of human development to this grave perturbation of the condition of the globe. The problem is sometimes wrongly conceived. The chief point to be determined is not whether man did or did not precede the Ice-Age. As it is the general belief that he was evolved in the Tertiary, it is clear that he existed in some part of the earth before the Ice-Age. Whether he had already penetrated as far north as Britain and Belgium is an interesting point, but not one of great importance. We may, therefore, refrain from discussing at any length those disputed crude stone implements (Eoliths) which, in the opinion of many, prove his presence in northern regions before the close of the Tertiary. We may also now disregard the remains of the Java Ape-Man. There are authorities, such as Deniker, who hold that even the latest research shows these remains to be Pliocene, but it is disputed. The Java race may be a surviving remnant of an earlier phase of human evolution. The most interesting subject for inquiry is the fortune of our human and prehuman forerunners during the Pliocene and Pleistocene periods. It may seem that if we set aside the disputable evidence of the Eoliths and the Java remains we can say nothing whatever on this subject. In reality a fact of very great interest can be established. It can be shown that the progress made during this enormous lapse of time--at least a million years--was remarkably slow. Instead of supposing that some extraordinary evolution took place in that conveniently obscure past, to which we can find no parallel within known times, it is precisely the reverse. The advance that has taken place within the historical period is far greater, comparatively to the span of time, than that which took place in the past. To make this interesting fact clearer we must attempt to measure the progress made in the Pliocene and Pleistocene. We may assume that the precursor of man had arrived at the anthropoid-ape level by the middle of the Miocene period. He is not at all likely to have been behind the anthropoid apes, and we saw that they were well developed in the mid-Tertiary. Now we have a good knowledge of man as he was in the later stage of the Ice-Age--at least a million years later--and may thus institute a useful comparison and form some idea of the advance made. In the later stages of the Pleistocene a race of men lived in Europe of whom we have a number of skulls and skeletons, besides vast numbers of stone implements. It is usually known as the Neanderthal race, as the first skeleton was found, in 1856, at Neanderthal, near Dusseldorf. Further skeletons were found at Spy, in Belgium, and Krapina, in Croatia. A skull formerly found at Gibraltar is now assigned to the same race. In the last five years a jaw of the same (or an earlier) age has been found at Mauer, near Heidelberg, and several skeletons have been found in France (La Vezere and Chapelle-aux-Saints). From these, and a few earlier fragments, we have a confident knowledge of the features of this early human race. The highest appreciation of the Neanderthal man--a somewhat flattering appreciation, as we shall see--is that he had reached the level of the Australian black of to-day. The massive frontal ridges over his eyes, the very low, retreating forehead, the throwing of the mass of the brain toward the back of the head, the outthrust of the teeth and jaws, and the complete absence (in some cases) or very slight development of the chin, combine to give the head what the leading authorities call a "bestial" or "simian" aspect. The frame is heavy, powerful, and of moderate height (usually from two to four inches over five feet). The thigh-bones are much more curved than in modern man. We cannot enter here into finer anatomical details, but all the features are consistent and indicate a stage in the evolution from ape-man to savage man. One point only calls for closer inquiry. Until a year or two ago it was customary to state that in cranial capacity also--that is to say, in the volume of brain-matter that the skull might contain--the Neanderthal race was intermediate between the Ape-Man and modern man. We saw above that the cranial capacity of the highest ape is about 600 cubic centimetres, and that of the Ape-Man (variously given as 850 and 950) is about 900. It was then added that the capacity of the Neanderthal race was about 1200, and that of civilised man (on the average) 1600. This seemed to be an effective and convincing indication of evolution, but recent writers have seriously criticised it. Sir Edwin Ray Lankester, Professor Sollas, and Dr. Keith have claimed in recent publications that the brain of Neanderthal man was as large as, if not larger than, that of modern man. [*] Professor Sollas even observes that "the brain increases in volume as we go backward." This is, apparently, so serious a reversal of the familiar statement in regard to the evolution of man that we must consider it carefully. *See especially an address by Professor Sollas in the Quarterly Journal of the Geological Society, Vol. LXVI. (1910). Largeness of brain in an individual is no indication of intelligence, and smallness of brain no proof of low mentality. Some of the greatest thinkers, such as Aristotle and Leibnitz, had abnormally small heads. Further, the size of the brain is of no significance whatever except in strict relation to the size and weight of the body. Woman has five or six ounces less brain-matter than man, but in proportion to her average size and the weight of the vital tissue of her body (excluding fat) she has as respectable a brain as man. When, however, these allowances have been made, it has usually been considered that the average brain of a race is in proportion to its average intelligence. This is not strictly true. The rabbit has a larger proportion of brain to body than the elephant or horse, and the canary a larger proportion than the chimpanzee. Professor Sollas says that the average cranial capacity of the Eskimo is 1546 cubic centimetres, or nearly that assigned to the average Parisian. Clearly the question is very complex, and some of these recent authorities conclude that the cranial capacity, or volume of the brain, has no relation to intelligence, and therefore the size of the Neanderthal skull neither confirms nor disturbs the theory of evolution. The wise man will suspend his judgment until the whole question has been fully reconsidered. But I would point out that some of the recent criticisms are exaggerated. The Gibraltar skull is estimated by Professor Sollas himself to have a capacity of about 1260; and his conclusion that it is an abnormal or feminine skull rests on no positive grounds. The Chapelle-aux-Saints skull ALONE is proved to have the high capacity of 1620; and it is as yet not much more than a supposition that the earlier skulls had been wrongly measured. But, further, the great French authority, M. Boule, who measured the capacity of the Chapelle-aux Saints skull, observes [*] that "the anomaly disappears" on careful study. He assures us that a modern skull of the same dimensions would have a capacity of 1800-1900 cubic centimetres, and warns us that we must take into account the robustness of the body of primitive man. He concludes that the real volume of the Neanderthal brain (in this highest known specimen) is "slight in comparison with the volume of the brain lodged in the large heads of to-day," and that the "bestial or ape-like characters" of the race are not neutralised by this gross measurement. *See his article in Anthropologie, Vol. XX. (1909), p. 257. As Professor Sollas mainly relies on Boule, it is important to see that there is a very great difference between the two. We must therefore hesitate to accept the statement that primitive man had as large a brain, if not a larger brain, than a modern race. The basis is slender, and the proportion of brain to body-tissue has not been taken into account. On the other hand, the remains of this early race are, Professor Sollas says, "obviously more brutal than existing men in all the other ascertainable characters by which they differ from them." Nor are we confined to precarious measurements of skulls. We have the remains of the culture of this early race, and in them we have a surer trace of its mental development. Here again we must proceed with caution, and set aside confused and exaggerated statements. Some refer us to the artistic work of primitive man. We will consider his drawings and carvings presently, but they belong to a later race, not the Neanderthal race. Some lay stress on the fact, apparently indicated in one or two cases out of a dozen, that primitive man buried his dead. Professor Sollas says that it indicates that even Neanderthal man had reached "a comparatively high stage in the evolution of religious ideas "; but the Australians bury their dead, and the highest authorities are not agreed whether they have any idea whatever of a supreme being or of morality. We must also disallow appeals to the use of fire, the taming of animals, pottery, or clothing. None of these things are clearly found in conjunction with the Neanderthal race. The only certain relic of Neanderthal culture is the implement which the primitive savage fashioned, by chipping or pressure, of flint or other hard stone. The fineness of some of these implements is no indication of great intelligence. The Neanderthal man inherited a stone culture which was already of great antiquity. At least one, if not two or three, prolonged phases of the Old Stone Age were already over when he appeared. On the most modest estimate men had by that time been chipping flints for several hundred thousand years, and it is no argument of general intelligence that some skill in the one industry of the age had been developed. The true measure of Neanderthal man's capacity is that, a million years or so after passing the anthropoid-age level, he chipped his stones more finely and gave them a better edge and contour. There is no evidence that he as yet hefted them. It is flattering to him to compare him with the Australian aboriginal. The native art, the shields and spears and boomerangs, and the elaborate tribal and matrimonial arrangements of the Australian black are not known to have had any counterpart in his life. It would therefore seem that the precursors of man made singularly little, if any, progress during the vast span of time between the Miocene and the Ice-Age, and that then something occurred which quickened the face of human evolution. From the Neanderthal level man will advance to the height of modern civilisation in about one-tenth the time that it took him to advance from the level of the higher ape to that of the lowest savage. Something has broken into the long lethargy of his primitive career, and set him upon a progressive path. Let us see if a careful review of the stages of his culture confirms the natural supposition that this "something" was the fall in the earth's temperature, and how it may have affected him. CHAPTER XX. THE DAWN OF CIVILISATION The story of man before the discovery of metal and the attainment of civilisation is notoriously divided into a Palaeolithic (Old Stone) Age, and a Neolithic (New Stone) Age. Each of these ages is now subdivided into stages, which we will review in succession. But it is important to conceive the whole story of man in more correct proportion than this familiar division suggests. The historical or civilised period is now computed at about ten thousand years. The Neolithic Age, which preceded civilisation, is usually believed to be about four or five times as long, though estimates of its duration vary from about twenty to a hundred thousand years. The Palaeolithic Age in turn is regarded as at least three or four times as long as the Neolithic; estimates of time vary from a hundred to five hundred thousand years. And before this there is the vast stretch of time in which the ape slowly became a primitive human. This long, early period is, as we saw, still wrapped in mist and controversy. A few bones tell of a race living, in semi-human shape, in the region of the Indian Ocean; a few crude stones are held by many to indicate that a more advanced, but very lowly race, wandered over the south of Europe and north of Africa before the Ice-Age set in. The starting-point or cradle of the race is not known. The old idea of seeking the patriarchal home on the plains to the north of India is abandoned, and there is some tendency to locate it in the land which has partly survived in the islands of the Indian Ocean. The finding of early remains in Java is not enough to justify that conclusion, but it obtains a certain probability when we notice the geographical distribution of the Primates. The femurs and the apes are found to-day in Africa and Asia alone; the monkeys have spread eastward to America and westward to Europe and Africa; the human race has spread north-eastward into Asia and America, northwestward into Europe, westward into Africa, and southward to Australia and the islands. This distribution suggests a centre in the Indian Ocean, where there was much more land in the Tertiary Era than there is now. We await further exploration in that region and Africa. There is nothing improbable in the supposition that man wandered into Europe in the Tertiary, and has left in the Eoliths the memorials of his lowly condition. The anthropoid apes certainly reached France. However that may be, the Ice-Age would restrict all the Primates to the south. It will be seen, on a glance at the map, that a line of ice-clad mountains would set a stern barrier to man's advance in the early Pleistocene, from the Pyrenees to the Himalaya, if not to the Pacific. He therefore spread westward and southward. One branch wandered into Australia, and was afterwards pressed by more advanced invaders (the present blacks of Australia) into Tasmania, which seems to have been still connected by land. Another branch, or branches, spread into Africa, to be driven southward, or into the central forests, by later and better equipped invaders. They survive, little changed (except by recent contact with Europeans), in the Bushmen and in large populations of Central Africa which are below the level of tribal organisation. Others remained in the islands, and we seem to have remnants of them in the Kalangs, Veddahs, etc. But these islands have been repeatedly overrun by higher races, and the primitive life has been modified. Comparing the most isolated of these relics of early humanity, we obtain many suggestions about the life of that remote age. The aboriginal Tasmanians, who died out about forty years ago, were of great evolutionary interest. It is sometimes said that man is distinguished from all other animals by the possession of abstract ideas, but the very imperfect speech of the Tasmanians expressed no abstract ideas. Their mind seems to have been in an intermediate stage of development. They never made fire, and, like the other surviving fragments of early humanity, they had no tribal organisation, and no ideas of religion or morality. The first effect of the Ice-Age on this primitive humanity would be to lead to a beginning of the development of racial characters. The pigment under the skin of the negro is a protection against the actinic rays of the tropical sun; the white man, with his fair hair and eyes, is a bleached product of the northern regions; and the yellow or brown skin seems to be the outcome of living in dry regions with great extremes of temperature. As the northern hemisphere divided into climatic zones these physical characters were bound to develop. The men who went southward developed, especially when fully exposed to the sun on open plains, the layer of black pigment which marks the negroid type. There is good reason, as we shall see to think that man did not yet wear clothing, though he had a fairly conspicuous, if dwindling, coat of hair. On the other hand the men who lingered further north, in South-western Asia and North Africa, would lose what pigment they had, and develop the lighter characters of the northerner. It has been noticed that even a year in the arctic circle has a tendency to make the eyes of explorers light blue. We may look for the genesis of the vigorous, light-complexioned races along the fringe of the great ice-sheet. It must be remembered that when the limit of the ice-sheet was in Central Germany and Belgium, the climate even of North Africa would be very much more temperate than it is to-day. As the ice-sheet melted, the men who were adapted to living in the temperate zone to the south of it penetrated into Europe, and the long story of the Old Stone Age opened. It must not, of course, be supposed that this stage of human culture only began with the invasion of Europe. Men would bring their rough art of fashioning implements with them, but the southern regions are too little explored to inform us of the earlier stage. But as man enters Europe he begins to drop his flints on a soil that we have constant occasion to probe--although the floor on which he trod is now sometimes forty or fifty feet below the surface--and we obtain a surer glimpse of the fortunes of our race. Most European geologists count four distinct extensions of the ice-sheet, with three interglacial periods. It is now generally believed that man came north in the third interglacial period; though some high authorities think that he came in the second. As far as England is concerned, it has been determined, under the auspices of the British Association, that our oldest implements (apart from the Eoliths) are later than the great ice-sheet, but there is some evidence that they precede the last extension of the ice. Two stages are distinguished in this first part of the Palaeolithic Age--the Acheulean and Chellean--but it will suffice for our purpose to take the two together as the earlier and longer section of the Old Stone Age. It was a time of temperate, if not genial, climate. The elephant (an extinct type), the rhinoceros, the hippopotamus, the hyaena, and many other forms of animal life that have since retired southward, were neighbours of the first human inhabitant of Europe. Unfortunately, we have only one bone of this primitive race, the jaw found at Mauer in 1907, but its massive size and chinless contour suggest a being midway between the Java man and the Neanderthal race. His culture confirms the supposition. There is at this stage no clear trace of fire, clothing, arrows, hefted weapons, spears, or social life. As the implements are generally found on old river-banks or the open soil, not in caves, we seem to see a squat and powerful race wandering, homeless and unclad, by the streams and broad, marshy rivers of the time. The Thames and the Seine had not yet scooped out the valleys on the slopes of which London and Paris are built. This period seems, from the vast number of stone implements referred to it, to have lasted a considerable time. There is a risk in venturing to give figures, but it may be said that few authorities would estimate it at less than a hundred thousand years. Man still advanced with very slow and uncertain steps, his whole progress in that vast period being measured by the invention of one or two new forms of stone implements and a little more skill in chipping them. At its close a great chill comes over Europe--the last ice-sheet is, it seems, spreading southward--and we enter the Mousterian period and encounter the Neanderthal race which we described in the preceding chapter. It must be borne in mind that the whole culture of primitive times is crushed into a few feet of earth. The anthropologist is therefore quite unable to show us the real succession of human stages, and has to be content with a division of the whole long and gradual evolution into a few well-marked phases. These phases, however, shade into each other, and are merely convenient measurements of a continuous story. The Chellean man has slowly advanced to a high level. There is no sudden incoming of a higher culture or higher type of man. The most impressive relics of the Mousterian period, which represent its later epoch, are merely finely chipped implements. There is no art as yet, no pottery, and no agriculture; and there is no clear trace of the use of fire or clothing, though we should be disposed to put these inventions in the chilly and damp Mousterian period. There is therefore no ground for resenting the description, "the primeval savage," which has been applied to early man. The human race is already old, yet, as we saw, it is hardly up to the level of the Australian black. The skeleton found at Chapelle-aux-Saints is regarded as the highest known type of the race, yet the greatest authority on it, M. Boule, says emphatically: "In no actual race do we find the characters of inferiority--that is to say, the ape-like features--which we find in the Chapelle-aux-Saints head." The largeness of the head is in proportion to the robust frame, but in its specifically human part--the front--it is very low and bestial; while the heavy ridges over the large eyes, the large flat stumpy nose, the thick bulge of the lips and teeth, and the almost chinless jaw, show that the traces of his ancestry cling close to man after some hundreds of thousands of years of development. The cold increases as we pass to the last part of the Old Stone Age, the Solutrean and Magdalenian periods; and nothing is clearer than that the pace of development increases at the same time. Short as the period is, in comparison with the preceding, it witnesses a far greater advance than had been made in all the rest of the Old Stone Age. Beyond a doubt men now live in caves, in large social groups, make clothing from the skins of animals, have the use of fire, and greatly improve the quality of their stone axes, scrapers, knives, and lance-heads. There is at last some promise of the civilisation that is coming. In the soil of the caverns in which man lived, especially in Southern France and the Pyrenean region, we find the debris of a much larger and fuller life. Even the fine bone needles with which primitive man sewed his skin garments, probably with sinews for thread, survive in scores. In other places we find the ashes of the fires round which he squatted, often associated with the bones of the wild horses, deer, etc., on which he lived. But the most remarkable indication of progress in the "cave-man" is his artistic skill. Exaggerated conclusions are sometimes drawn from the statuettes, carvings, and drawings which we find among the remains of Magdalenian life. Most of them are crude, and have the limitations of a rustic or a child artist. There is no perspective, no grouping. Animals are jumbled together, and often left unfinished because the available space was not measured. There are, however, some drawings--cut on bone or horn or stone with a flint implement--which evince great skill in line-drawing and, in a few cases, in composition. Some of the caves also are more or less frescoed; the outlines of animals, sometimes of life-size and in great numbers, are cut in the wall, and often filled in with pigment. This skill does not imply any greater general intelligence than the rest of the culture exhibits. It implies persistent and traditional concentration upon the new artistic life. The men who drew the "reindeer of Thayngen" and carved the remarkable statuettes of women in ivory or stone, were ignorant of the simplest rudiments of pottery or agriculture, which many savage tribes possess. Some writers compare them with the Eskimo of to-day, and even suggest that the Eskimo are the survivors of the race, retreating northward with the last ice-sheet, and possibly egged onward by a superior race from the south. It is, perhaps, not a very extravagant claim that some hundreds of thousands of years of development--we are now only a few tens of thousands of years from the dawn of civilisation--had lifted man to the level of the Eskimo, yet one must hesitate to admit the comparison. Lord Avebury reproduces an Eskimo drawing, or picture-message, in his "Prehistoric Times," to which it would be difficult to find a parallel in Magdalenian remains. I do not mean that the art is superior, but the complex life represented on the picture-message, and the intelligence with which it is represented, are beyond anything that we know of Palaeolithic man. I may add that nearly all the drawings and statues of men and women which the Palaeolithic artist has left us are marked by the intense sexual exaggeration--the "obscenity," in modern phraseology--which we are apt to find in coarse savages. Three races are traced in this period. One, identified by skeletons found at Mentone and by certain statuettes, was negroid in character. Probably there was an occasional immigration from Africa. Another race (Cro-Magnon) was very tall, and seems to represent an invasion from some other part of the earth toward the close of the Old Stone Age. The third race, which is compared to the Eskimo, and had a stature of about five feet, seem to be the real continuers of the Palaeolithic man of Europe. Curiously enough, we have less authentic remains of this race than of its predecessor, and can only say that, as we should expect, the ape-like features--the low forehead, the heavy frontal ridges, the bulging teeth, etc.--are moderating. The needles we have found--round, polished, and pierced splinters of bone, sometimes nearly as fine as a bodkin--show indisputably that man then had clothing, but it is curious that the artist nearly always draws him nude. There is also generally a series of marks round the contour of the body to indicate that he had a conspicuous coat of hair. Unfortunately, the faces of the men are merely a few unsatisfactory gashes in the bone or horn, and do not picture this interesting race to us. The various statuettes of women generally suggest a type akin to the wife of the Bushman. We have, in fine, a race of hunters, with fine stone knives and javelins. Toward the close of the period we find a single representation of an arrow, which was probably just coming into use, but it is not generally known in the Old Stone Age. One of the drawings seems to represent a kind of bridle on a horse, but we need more evidence than this to convince us that the horse was already tamed, nor is there any reason to suppose that the dog or reindeer had been tamed, or that the ground was tilled even in the most rudimentary way. Artistic skill, the use of clothing and fire, and a finer feeling in the shaping of weapons and implements, are the highest certain indications of the progress made by the end of the Old Stone Age. But there was probably an advance made which we do not find recorded, or only equivocally recorded, in the memorials of the age. Speech was probably the greatest invention of Magdalenian man. It has been pointed out that the spine in the lower jaw, to which the tongue-muscle is attached, is so poorly developed in Palaeolithic man that we may infer from it the absence of articulate speech. The deduction has been criticised, but a comparison of the Palaeolithic jaw with that of the ape on one hand and modern man on the other gives weight to it. Whatever may have been earlier man's power of expression, the closer social life of the Magdalenian period would lead to a great development of it. Some writers go so far as to suggest that certain obscure marks painted on pebbles or drawn on the cavern-walls by men at the close of the Palaeolithic Age may represent a beginning of written language, or numbers, or conventional signs. The interpretation of these is obscure and doubtful. It is not until ages afterwards that we find the first clear traces of written language, and then they take the form of pictographs (like the Egyptian hieroglyphics or the earliest Chinese characters). We cannot doubt, however, that articulate speech would be rapidly evolved in the social life of the later Magdalenian period, and the importance of this acquisition can hardly be exaggerated. Imagine even a modern community without the device of articulate language. A very large proportion of the community, who are now maintained at a certain level by the thought of others, communicated to them by speech, would sink below the civilised standard, and the transmission and improvement of ideas would be paralysed. It would not be paradoxical to regard the social life and developing speech of Magdalenian man as the chief cause of the rapid advance toward civilisation which will follow in the next period. And it is not without interest to notice that a fall in the temperature of the earth is the immediate cause of this social life. The building of homes of any kind seems to be unknown to Magdalenian man. The artist would have left us some sketchy representation of it if there had been anything in the nature of a tent in his surroundings. The rock-shelter and the cave are the homes which men seek from the advancing cold. As these are relatively few in number, fixed in locality, and often of large dimensions, the individualism of the earlier times is replaced by collective life. Sociologists still dispute whether the clan arose by the cohesion of families or the family arose within the clan. Such evidence as is afforded by prehistoric remains is entirely in favour of the opinion of Professor Westermarck, that the family preceded the larger group. Families of common descent would now cling together and occupy a common cavern, and, when the men gathered at night with the women for the roasting and eating of the horse or deer they had hunted, and the work of the artist and the woman was considered, the uncouth muttering and gesticulating was slowly forged into the great instrument of articulate speech. The first condition of more rapid progress was instinctively gained. Our story of life has so often turned on this periodical lowering of the climate of the earth that it is interesting to find this last and most important advance so closely associated with it that we are forced once more to regard it as the effective cause. The same may be said of another fundamental advance of the men of the later Palaeolithic age, the discovery of the art of making fire. It coincides with the oncoming of the cold, either in the Mousterian or the Magdalenian. It was more probably a chance discovery than an invention. Savages so commonly make fire by friction--rubbing sticks, drills, etc.--that one is naturally tempted to regard this as the primitive method. I doubt if this was the case. When, in Neolithic times, men commonly bury the dead, and put some of their personal property in the grave with them, the fire-kindling apparatus we find is a flint and a piece of iron pyrites. Palaeolithic man made his implements of any kind of hard and heavy stone, and it is probable that he occasionally selected iron ore for the purpose. An attempt to chip it with flint would cause sparks that might fall on inflammable material, and set it alight. Little intelligence would be needed to turn this discovery to account. Apart from these conjectures as to particular features in the life of prehistoric man, it will be seen that we have now a broad and firm conception of its evolution. From the ape-level man very slowly mounts to the stage of human savagery. During long ages he seems to have made almost no progress. There is nothing intrinsically progressive in his nature. Let a group of men be isolated at any stage of human evolution, and placed in an unchanging environment, and they will remain stationary for an indefinite period. When Europeans began to traverse the globe in the last few centuries, they picked up here and there little groups of men who had, in their isolation, remained just where their fathers had been when they quitted the main road of advance in the earlier stages of the Old Stone Age. The evolution of man is guided by the same laws as the evolution of any other species. Thus we can understand the long period of stagnation, or of incalculably slow advance. Thus, too, we can understand why, at length, the pace of man toward his unconscious goal is quickened. He is an inhabitant of the northern hemisphere, and the northern hemisphere is shaken by the last of the great geological revolutions. From its first stress emerges the primeval savage of the early part of the Old Stone Age, still bearing the deep imprint of his origin, surpassing his fellow-animals only in the use of crude stone implements. Then the stress of conditions relaxes--the great ice-sheet disappears--and again during a vast period he makes very little progress. The stress returns. The genial country is stripped and impoverished, and the reindeer and mammoth spread to the south of Europe. But once more the adversity has its use, and man, stimulated in his hunt for food, invigorated by the cold, driven into social life, advances to the culmination of the Old Stone Age. We are still very far from civilisation, but the few tens of thousands of years that separate Magdalenian man from it will be traversed with relative speed--though, we should always remember, with a speed far less than the pace at which man is advancing to-day. A new principle now enters into play: a specifically human law of evolution is formulated. It has no element of mysticism, and is merely an expression of the fact that the previous general agencies of development have created in man an intelligence of a higher grade than that of any other animal. In his larger and more plastic brain the impressions received from the outer world are blended in ideas, and in his articulate speech he has a unique means of entering the idea-world of his fellows. The new principle of evolution, which arises from this superiority, is that man's chief stimulus to advance will now come from his cultural rather than his physical environment. Physical surroundings will continue to affect him. One race will outstrip another because of its advantage in soil, climate, or geographical position. But the chief key to the remaining and more important progress of mankind, which we are about to review, is the stimulating contact of the differing cultures of different races. This will be seen best in the history of civilisation, but the principle may be recognised in the New Stone Age which leads from primeval savagery to civilisation, or, to be more accurate and just, to the beginning of the historical period. It used to be thought that there was a mysterious blank or gulf between the Old and the New Stone Age. The Palaeolithic culture seemed to come to an abrupt close, and the Neolithic culture was sharply distinguished from it. It was suspected that some great catastrophe had destroyed the Palaeolithic race in Europe, and a new race entered as the adverse conditions were removed. This was especially held to be the case in England. The old Palaeolithic race had never reached Ireland, which seems to have been cut oft from the Continent during the Ice-Age, and most of the authorities still believe--in spite of some recent claims--that it never reached Scotland. England itself was well populated, and the remains found in the caves of Derbyshire show that even the artist--or his art--had reached that district. This Palaeolithic race seemed to come to a mysterious end, and Europe was then invaded by the higher Neolithic race. England was probably detached from the Continent about the end of the Magdalenian period. It was thought that some great devastation--the last ice-sheet, a submersion of the land, or a plague--then set in, and men were unable to retreat south. It is now claimed by many authorities that there are traces of a Middle Stone (Mesolithic) period even in England, and nearly all the authorities admit that such a transitional stage can be identified in the Pyrenean region. This region had been the great centre of the Magdalenian culture. Its large frescoed caverns exhibit the culmination of the Old Stone life, and afford many connecting links with the new. It is, however, a clearly established and outstanding fact that the characteristic art of Magdalenian man comes to an abrupt and complete close, and it does not seem possible to explain this without supposing that the old race was destroyed or displaced. If we could accept the view that it was the Eskimo-like race of the Palaeolithic that cultivated this art, and that they retreated north with the reindeer and the ice, and survive in our Eskimo, we should have a plausible explanation. In point of fact, we find no trace whatever of this slow migration from the south of Europe to the north. The more probable supposition is that a new race, with more finished stone implements, entered Europe, imposed its culture upon the older race, and gradually exterminated or replaced it. We may leave it open whether a part of the old race retreated to the north, and became the Eskimo. Whence came the new race and its culture? It will be seen on reflection that we have so far been studying the evolution of man in Europe only, because there alone are his remains known with any fullness. But the important region which stretches from Morocco to Persia must have been an equally, if not more, important theatre of development. While Europe was shivering in the last stage of the Ice-Age, and the mammoth and reindeer browsed in the snows down to the south of France, this region would enjoy an excellent climate and a productive soil. We may confidently assume that there was a large and stirring population of human beings on it during the Magdalenian cold. We may, with many of the authorities, look to this temperate and fertile region for the slight advance made by early Neolithic man beyond his predecessor. As the cold relaxed, and the southern fringe of dreary steppe w as converted once more into genial country, the race would push north. There is evidence that there were still land bridges across the Mediterranean. From Spain and the south of France this early Neolithic race rapidly spread over Europe. It must not be supposed that the New Stone Age at first goes much beyond the Old in culture. Works on prehistoric man are apt to give as features of "Neolithic man" all that we know him to have done or discovered during the whole of the New Stone Age. We read that he not only gave a finer finish to, and sometimes polished, his stone weapons, but built houses, put imposing monuments over his dead, and had agriculture, tame cattle, pottery, and weaving. This is misleading, as the more advanced of these accomplishments appear only late in the New Stone Age. The only difference we find at first is that the stone axes, etc., are more finely chipped or flaked, and are frequently polished by rubbing on stone moulds. There is no sudden leap in culture or intelligence in the story of man. It would be supremely interesting to trace the evolution of human industries and ideas during the few tens of thousands of years of the New Stone Age. During that time moral and religious ideas are largely developed, political or social forms are elaborated, and the arts of civilised man have their first rude inauguration. The foundations of civilisation are laid. Unfortunately, precisely because the period is relatively so short and the advance so rapid, its remains are crushed and mingled in a thin seam of the geological chronicle, and we cannot restore the gradual course of its development with any confidence. Estimates of its duration vary from 20,000 to 70,000 years; though Sir W. Turner has recently concluded, from an examination of marks on Scottish monuments, that Neolithic man probably came on foot from Scandinavia to Scotland, and most geologists would admit that it must be at least a hundred thousand years since one could cross from Norway to Scotland on foot. As usual, we must leave open the question of chronology, and be content with a modest provisional estimate of 40,000 or 50,000 years. We dimly perceive the gradual advance of human culture in this important period. During the Old Stone Age man had made more progress than he had made in the preceding million years; during the New Stone Age--at least one-fourth as long as the Old--he made even greater progress; and, we may add, in the historical period, which is one-fourth the length of the Neolithic Age, he will make greater progress still. The pace of advance naturally increases as intelligence grows, but that is not the whole explanation. The spread of the race, the gathering of its members into tribes, and the increasing enterprise of men in hunting and migration, lead to incessant contacts of different cultures and a progressive stimulation. At first Neolithic man is content with finer weapons. His stone axe is so finely shaped and polished that it sometimes looks like forged or moulded metal. He also drills a clean hole through it--possibly by means of a stick working in wet sand--and gives it a long wooden handle. He digs in the earth for finer flints, and in some of his ancient shafts (Grimes, Graves and Cissbury) we find picks of reindeer horn and hollowed blocks of chalk in which he probably burned fat for illumination underground. But in the later part of the Neolithic--to which much of this finer work also may belong--we find him building huts, rearing large stone monuments, having tame dogs and pigs and oxen, growing corn and barley, and weaving primitive fabrics. He lives in large and strong villages, round which we must imagine his primitive cornfields growing and his cattle grazing, and in which there must have been some political organisation under chiefs. When we wish to trace the beginning of these inventions we have the same difficulty that we experienced in tracing the first stages of new animal types. The beginning takes place in some restricted region, and our casual scratching of the crust of the earth or the soil may not touch it for ages, if it has survived at all. But for our literature and illustrations a future generation would be equally puzzled to know how we got the idea of the aeroplane or the electric light. In some cases we can make a good guess at the origin of Neolithic man's institutions. Let us take pottery. Palaeolithic man cooked his joint of horse or reindeer, and, no doubt, scorched it. Suppose that some Palaeolithic Soyer had conceived the idea of protecting the joint, and preserving its juices, by daubing it with a coat of clay. He would accidentally make a clay vessel. This is Mr. Clodd's ingenious theory of the origin of pottery. The development of agriculture is not very puzzling. The seed of corn would easily be discovered to have a food-value, and the discovery of the growth of the plant from the seed would not require a very high intelligence. Some ants, we may recall, have their fungus-beds. It would be added by many that the ant gives us another parallel in its keeping of droves of aphides, which it "milks." But it is now doubted if the ant deliberately cultivates the aphides with this aim. Early weaving might arise from the plaiting of grasses. If wild flax were used, it might be noticed that part of it remained strong when the rest decayed, and so the threads might be selected and woven. The building of houses, after living for ages in stone caverns, would not be a very profound invention. The early houses were--as may be gathered from the many remains in Devonshire and Cornwall--mere rings of heaped stones, over which, most probably, was put a roof of branches or reeds, plastered with mud. They belong to the last part of the New Stone Age. In other places, chiefly Switzerland, Neolithic man lived in wooden huts built on piles in the shallow shores of lakes. It is an evidence that life on land is becoming as stimulating as we find it in the age of Deinosaurs or early mammals. These pile-villages of Switzerland lasted until the historical period, and the numerous remains in the mud of the lake show the gradual passage into the age of metal. Before the metal age opened, however, there seem to have been fresh invasions of Europe and changes of its culture. The movements of the various early races of men are very obscure, and it would be useless to give here even an outline of the controversy. Anthropologists have generally taken the relative length and width of the skull as a standard feature of a race, and distinguished long-headed (dolichocephalic), short-headed (brachycephalic), and middle-headed (mesaticephalic) races. Even on this test the most divergent conclusions were reached in regard to early races, and now the test itself is seriously disputed. Some authorities believe that there is no unchanging type of skull in a particular race, but that, for instance, a long-headed race may become short-headed by going to live in an elevated region. It may be said, in a few words, that it is generally believed that two races invaded Europe and displaced the first Neolithic race. The race which chiefly settled in the Swiss region is generally believed to have come from Asia, and advanced across Europe by way of the valley of the Danube. The native home of the wheat and barley and millet, which, as we know, the lake-dwellers cultivated, is said to be Asia. On the other hand, the Neolithic men who have left stone monuments on our soil are said to be a different race, coming, by way of North Africa, from Asia, and advancing along the west of Europe to Scandinavia. A map of the earth, on which the distribution of these stone monuments--all probably connected with the burial of the dead--is indicated, suggests such a line of advance from India, with a slighter branch eastward. But the whole question of these invasions is disputed, and there are many who regard the various branches of the population of Europe as sections of one race which spread upward from the shores of the Mediterranean. It is clear at least that there were great movements of population, much mingling of types and commercial interchange of products, so that we have the constant conditions of advance. A last invasion seems to have taken place some two or three thousand years before the Christian era, when the Aryans overspread Europe. After all the controversy about the Aryans it seems clear that a powerful race, representing the ancestors of most of the actual peoples of Europe and speaking the dialects which have been modified into the related languages of the Greeks, Romans, Germans, Celts, Lithuanians, etc., imposed its speech on nearly the whole of the continent. Only in the Basques and Picts do we seem to find some remnants of the earlier non-Aryan tongues. But whether these Aryans really came from Asia, as it used to be thought, or developed in the east of Europe, is uncertain. We seem justified in thinking that a very robust race had been growing in numbers and power during the Neolithic Age, somewhere in the region of South-east Europe and Southwest Asia, and that a few thousand years before the Christian Era one branch of it descended upon India, another upon the Persian region, and another overspread Europe. We will return to the point later. Instead of being the bearers of a higher civilisation, these primitive Aryans seem to have been lower in culture than the peoples on whom they fell. The Neolithic Age had meantime passed into the Age of Metal. Copper was probably the first metal to be used. It is easily worked, and is found in nature. But the few copper implements we possess do not suggest a "Copper Age" of any length or extent. It was soon found, apparently, that an admixture of tin hardened the copper, and the Bronze Age followed. The use of bronze was known in Egypt about 4800 B.C. (Flinders Petrie), but little used until about 2000 B.C. By that time (or a few centuries later) it had spread as far as Scandinavia and Britain. The region of invention is not known, but we have large numbers of beautiful specimens of bronze work--including brooches and hair-pins--in all parts of Europe. Finally, about the thirteenth century B.C., we find the first traces of the use of iron. The first great centre for the making of iron weapons seems to have been Hallstatt, in the Austrian Alps, whence it spread slowly over Europe, reaching Scandinavia and Britain between 500 and 300 B.C. But the story of man had long before this entered the historical period, to which we now turn. CHAPTER XXI. EVOLUTION IN HISTORY In the preceding chapters I have endeavoured to show how, without invoking any "definitely directed variations," which we seem to have little chance of understanding, we may obtain a broad conception of the way in which the earth and its living inhabitants came to be what they are. No one is more conscious than the writer that this account is extremely imperfect. The limits of the volume have permitted me to use only a part of the material which modern science affords, but if the whole of our discoveries were described the sketch would still remain very imperfect. The evolutionary conception of the world is itself undergoing evolution in the mind of man. Age by age the bits of fresh discovery are fitted into the great mosaic. Large areas are still left for the scientific artist of the future to fill. Yet even in its imperfect state the evolutionary picture of the world is most illuminating. The questions that have been on the lips of thoughtful men since they first looked out with adult eyes on the panorama of nature are partly answered. Whence and Why are no longer sheer riddles of the sphinx. It remains to be seen if evolutionary principles will throw at least an equal light on the progress of humanity in the historical period. Here again the questions, Whence and Why, have been asked in vain for countless ages. If man is a progressive animal, why has the progress been confined to some of the race? If humanity shared at first a common patrimony, why have the savages remained savages, and the barbarians barbaric? Why has progress been incarnated so exceptionally in the white section of the race, the Europeans? We approach these questions more confidently after surveying the story of terrestrial life in the light of evolutionary principles. Since the days of the primeval microbe it has happened that a few were chosen and many were left behind. There was no progressive element in the advancing few that was not shared by the stagnant many. The difference lay in the environment. Let us see if this principle applies to the history of civilisation. In the last chapter I observed that, with the rise of human intelligence, the cultural environment becomes more important than the physical. Since human progress is a progress in ideas and the emotions which accompany them, this may seem to be a truism. In point of fact it is assailed by more than one recent historical writer. The scepticism is partly due to a misunderstanding. No one but a fanatical adherent of extreme theories of heredity will deny that the physical surroundings of a race continue to be of great importance. The progress of a particular people may often be traced in part to its physical environment; especially to changes of environment, by migration, for instance. Further, it is not for a moment suggested that a race never evolves its own culture, but has always to receive it from another. If we said that, we should be ultimately driven to recognise culture, like the early Chinese, as a gift of the gods. What is meant is that the chief key to the progress of certain peoples, the arrest of progress in others, and the entire absence of progress in others, is the study of their relations with, or isolation from, other peoples. They make progress chiefly according to the amount of stimulation they get by contact with a diverse culture. Let us see if this furnishes a broad explanation of the position of the various peoples of the world. The Ethnologist tells us that the lowest peoples of the earth are the Yahgans of Tierra del Fuego, the Hottentots, a number of little-understood peoples in Central Africa, the wild Veddahs of Ceylon, the (extinct) Tasmanians, the Aetas in the interior of the Philippines, and certain fragments of peoples on islands of the Indian Ocean. There is not the least trace of a common element in the environment of these peoples to explain why they have remained at the level of primitive humanity. Many of them lived in the most promising and resourceful surroundings. What is common to them all is their isolation from the paths of later humanity. They represent the first wave of human distribution, pressed to the tips of continents or on islands by later waves, and isolated. The position of the Veddahs is, to some extent, an exception; and it is interesting to find that the latest German students of that curious people think that they have been classed too low by earlier investigators. We cannot run over all the peoples of the earth in this way, but will briefly glance at the lower races of the various continents. A branch of the second phase of developing humanity, the negroid stock, spread eastward over the Asiatic islands and Australia, and westward into Africa. The extreme wing of this army, the Australian blacks, too clearly illustrates the principle to need further reference. It has retained for ages the culture of the middle Palaeolithic. The negritos who penetrated to the Philippines are another extreme instance of isolation. The Melanesians of the islands of the Indian and Pacific Ocean are less low, because those islands have been slowly crossed by a much higher race, the Polynesians. The Maoris of New Zealand, the Tongans, Hawaians, etc., are people of our own (Caucasic) stock, probably diverging to the south-east while our branch of the stock pressed westward. This not only explains the higher condition of the Maoris, etc., but also shows why they have not advanced like their European cousins. Their environment is one of the finest in the world, but--it lies far away from the highways of culture. In much the same way can we interpret the swarming peoples of Africa. The more primitive peoples which arrived first, and were driven south or into the central forests by the later and better equipped invaders from the central zone, have remained the more primitive. The more northern peoples, on the fringe of, or liable to invasion from, the central zone, have made more advance, and have occasionally set up rudimentary civilisations. But the movements from the north to the south in early historical times are too obscure to enable us to trace the action of the principle more clearly. The peoples of the Mediterranean fringe of Africa, living in the central zone of stimulation, have proved very progressive. Under the Romans North Africa was at least as civilised as Britain, and an equally wise and humane European policy might lead to their revival to-day. When we turn to Asia we encounter a mass of little-understood peoples and a few civilisations with obscure histories, but we have a fairly clear application of the principle. The northern, more isolated peoples, are the more primitive; the north-eastern, whose isolation is accentuated by a severe environment, are most primitive of all. The Eskimo, whether they are the survivors of the Magdalenian race or a regiment thrown off the Asiatic army as it entered America, remain at the primitive level. The American peoples in turn accord with this view. Those which penetrate furthest south remain stagnant or deteriorate; those which remain in the far north remain below the level of civilisation, because the land-bridge to Asia breaks down; but those which settle in Central America evolve a civilisation. A large zone, from Mexico to Peru, was overspread by this civilisation, and it was advancing steadily when European invaders destroyed it, and reduced the civilised Peruvians to the Quichas of to-day. There remain the civilisations of Asia, and here we have a new and interesting aspect of the question. How did these civilisations develop in Asia, and how is it that they have remained stagnant for ages, while Europe advanced? The origin of the Asiatic civilisations is obscure. The common idea of their vast antiquity has no serious ground. The civilisation of Japan cannot be traced back beyond about the eighth century B.C. Even then the population was probably a mixed flotsam from neighbouring lands--Ainus, Koreans, Chinese, and Malays. What was the character of the primitive civilisation resulting from the mixture of these different cultures we do not know. But the chief elements of Japanese civilisation came later from China. Japan had no written language of any kind until it received one from China about the sixth century of the Christian Era. The civilisation of China itself goes back at least to about 2300 B.C., but we cannot carry it further back with any confidence. The authorities, endeavouring to pick their steps carefully among old Chinese legends, are now generally agreed that the primitive Chinese were a nomadic tribe which slowly wandered across Asia from about the shores of the Caspian Sea. In other words, they started from a region close to the cradle of western civilisation. Some students, in fact, make them akin to the Akkadians, who founded civilisation in Mesopotamia. At all events, they seem to have conveyed a higher culture to the isolated inhabitants of Western Asia, and a long era of progress followed their settlement in a new environment. For more than two thousand years, however, they have been enclosed in their walls and mountains and seas, while the nations of the remote west clashed unceasingly against each other. We need no other explanation of their stagnation. To speak of the "unprogressiveness" of the Chinese is pure mysticism. The next generation will see. The civilisation of India is also far later than the civilisation of the west, and seems to be more clearly due to borrowing from the west. The primitive peoples who live on the hills about India, or in the jungles, are fragments, apparently, of the Stone Age inhabitants of India, or their descendants. Their culture may have degenerated under the adverse conditions of dislodgement from their home, but we may fairly conclude that it was never high. On these primitive inhabitants of the plains of India there fell, somewhere about or before 1000 B.C., the Asiatic branch of the Aryan race. A very recent discovery (1908) has strongly confirmed and illumined this view of the origin of Indian civilisation. Explorers in the ruins of the ancient capital of the Hittite Empire (in North Syria and Cappadocia) found certain treaties which had been concluded, about 1300 B.C., between the Hittites and the king of the Aryans. The names of the deities which are mentioned in the treaties seem to show that the Persian and Indian branches of the Aryan race were not yet separated, but formed a united kingdom on the banks of the Euphrates. They seem to have come from Bactria (and possibly beyond), and introduced the horse (hitherto unknown to the Babylonians) about 1800 B.C. It is surmised by the experts that the Indian and Persian branches separated soon after 1300 B.C., possibly on account of religious quarrels, and the Sanscrit-speaking branch, with its Vedic hymns and its Hinduism, wandered eastward and northward until it discovered and took possession of the Indian peninsula. The long isolation of India, since the cessation of its commerce with Rome until modern times, explains the later stagnation of its civilisation. Thus the supposed "non-progressiveness" of the east, after once establishing civilisation, turns out to be a question of geography and history. We have now to see if the same intelligible principles will throw light on the "progressiveness" of the western branch of the Aryan race, and on the course of western civilisation generally. [*] * In speaking of Europeans as Aryans I am, of course, allowing for an absorption of the conquered non-Aryans. A European nation is no more Aryan, in strict truth, than the English are Anglo-Saxon. The first two centres of civilisation are found in the valley of the Nile and the valley of the Tigris and Euphrates; the civilisations of Egypt and Babylon, the oldest in the world. There is, however, a good deal of evidence by which we may bring these civilisations nearer to each other in their earliest stages, so that we must not confidently speak of two quite independent civilisations. The civilisation which developed on the Euphrates is found first at Susa, on the hills overlooking the plains of Mesopotamia, about 6000 B.C. A people akin to the Turkish or Chinese lives among the hills, and makes the vague advance from higher Neolithic culture to primitive civilisation. About the same time the historical or dynastic civilisation begins in Egypt, and some high authorities, such as Mr. Flinders Petrie, believe that the evidence suggests that the founders of this dynastic civilisation came from "the mountainous region between Egypt and the Red Sea." From the northern part of the same region, we saw, the ancestors of the Chinese set out across Asia. We have here a very suggestive set of facts in connection with early civilisation. The Syro-Arabian region seems to have been a thickly populated centre of advancing tribes, which would be in striking accord with the view of progress that I am following. But we need not press the disputed and obscure theory of the origin of the historic Egyptians. The remains are said to show that the lower valley of the Nile, which must have been but recently formed by the river's annual deposit of mud, was a theatre of contending tribes from about 8000 to 6000 B.C. The fertile lands that had thus been provided attracted tribes from east, west, and south, and there is a great confusion of primitive cultures on its soil. It is not certain that the race which eventually conquered and founded the historical dynasties came from the mountainous lands to the east. It is enough for us to know that the whole region fermented with jostling peoples. Why it did so the previous chapters will explain. It is the temperate zone into which men had been pressed by the northern ice-sheet, and from Egypt to the Indian Ocean it remained a fertile breeding-ground of nations. These early civilisations are merely the highest point of Neolithic culture. The Egyptian remains show a very gradual development of pottery, ornamentation, etc., into which copper articles are introduced in time. The dawn of civilisation is as gradual as the dawn of the day. The whole gamut of culture--Eolithic, Palaeolithic, Neolithic, and civilised--is struck in the successive layers of Egyptian remains. But to give even a summary of its historical development is neither necessary nor possible here. The maintenance of its progress is as intelligible as its initial advance. Unlike China, it lay in the main region of human development, and we find that even before 6000 B.C. it developed a system of shipping and commerce which kept it in touch with other peoples over the entire region, and helped to promote development both in them and itself. Equally intelligible is the development of civilisation in Mesopotamia. The long and fertile valley which lies between the mountainous region and the southern desert is, like the valley of the Nile, a quite recent formation. The rivers have gradually formed it with their deposit in the course of the last ten thousand years. As this rich soil became covered with vegetation, it attracted the mountaineers from the north. As I said, the earliest centre of the civilisation which was to culminate in Babylon and Nineveh is traced at Susa, on the hills to the north, about 6000 B.C. The Akkadians (highlanders) or Sumerians, the Turanian people who established this civilisation, descended upon the rivers, and, about 5000 B.C., set up the early cities of Mesopotamia. As in the case of Egypt, again, more tribes were attracted to the fertile region, and by about 4000 B.C. we find that Semitic tribes from the north have superseded the Sumerians, and taken over their civilisation. In these ancient civilisations, developing in touch with each other, and surrounded by great numbers of peoples at the high Neolithic level from which they had themselves started, culture advanced rapidly. Not only science, art, literature, commerce, law, and social forms were developed, but moral idealism reached a height that compares well even with that of modern times. The recovery in our time of the actual remains of Egypt and Babylon has corrected much of the libellous legend, which found its way into Greek and European literature, concerning those ancient civilisations. But, as culture advances, human development becomes so complex that we must refrain from attempting to pursue, even in summary, its many outgrowths. The evolution of morality, of art, of religion, of polity, and of literature would each require a whole volume for satisfactory treatment. All that we can do here is to show how the modern world and its progressive culture are related to these ancient empires. The aphorism that "all light comes from the east" may at times be pressed too literally. To suggest that western peoples have done no more than receive and develop the culture of the older east would be at once unscientific and unhistorical. By the close of the Neolithic age a great number of peoples had reached the threshold of civilisation, and it would be extremely improbable that in only two parts of the world the conditions would be found of further progress. That the culture of these older empires has enriched Europe and had a great share in its civilisation, is one of the most obvious of historical truths. But we must not seek to confine the action of later peoples to a mere borrowing of arts or institutions. Yet some recent historical writers, in their eagerness to set up indigenous civilisations apart from those of Egypt and Mesopotamia, pass to the opposite extreme. We are prepared to find civilisation developing wherever the situation of a people exposes it to sufficient stimulation, and we do find advance made among many peoples apart from contact with the great southern empires. It is uncertain whether the use of bronze is due first to the southern nations or to some European people, but the invention of iron weapons is most probably due to European initiative. Again, it is now not believed that the alphabets of Europe are derived from the hieroglyphics of Egypt, though it is an open question whether they were not derived, through Phoenicia, from certain signs which we find on ancient Egyptian pottery. If we take first a broad view of the later course of civilisation we see at a glance the general relation of east and west. Some difficulty would arise, if we pressed, as to the exact stage in which a nation may be said to become "civilised," but we may follow the general usage of archaeologists and historians. They tell us, then, that civilisation first appears in Egypt about 8000 B.C. (settled civilisation about 6000 B.C.), and in the Mesopotamian region about 6000 B.C. We next find Neolithic culture passing into what may be called civilisation in Crete and the neighbouring islands some time between 4000 and 3000 B.C., or two thousand years after the development of Egyptian commerce in that region. We cannot say whether this civilisation in the AEgean sea preceded others which we afterwards find on the Asiatic mainland. The beginning of the Hittite Empire in Asia Minor, and of Phoenician culture, is as yet unknown. But we can say that there was as yet no civilisation in Europe. It is not until after 1600 that civilisation is established in Greece (Mycenae and Tiryns) as an offshoot of AEgean culture. Later still it appears among the Etruscans of Italy--to which, as we know, both Egyptian and AEgean vessels sailed. In other words, the course of civilisation is very plainly from east to west. But we must be careful not to imagine that this represents a mere transplantation of southern culture on a rude northern stock. The whole region to the east of the Mediterranean was just as fitted to develop a civilisation as the valley of the Nile. It swarmed with peoples having the latest Neolithic culture, and, as they advanced, and developed navigation, the territory of many of them became the high road of more advanced peoples. A glance at the map will show that the easiest line of expansion for a growing people was westward. The ocean lay to the right of the Babylonians, and the country north and south was not inviting. The calmer Mediterranean with its fertile shores was the appointed field of expansion. The land route from Egypt lay, not to the dreary west in Africa, but along the eastern shore of the Mediterranean, through Syria and Asia Minor. The land route from Babylon lay across northern Syria and Asia Minor. The sea route had Crete for its first and most conspicuous station. Hence the gradual appearance of civilisation in Phoenicia, Cappadocia, Lydia, and the Greek islands is a normal and natural outcome of the geographical conditions. But we must dismiss the later Asiatic civilisations, whose remains are fast coming to light, very briefly. Phoenicia probably had less part in the general advance than was formerly supposed. Now that we have discovered a powerful civilisation in the Greek islands themselves, we see that it would keep Tyre and Sidon in check until it fell into decay about 1000 B.C. After that date, for a few centuries, Phoenicia had a great influence on the development of Europe. The Hittites, on the other hand, are as yet imperfectly known. Their main region was Cappadocia, where, at least as far back as 1500 B.C., they developed so characteristic a civilisation, that its documents or inscriptions are almost undecipherable. They at one time overran the whole of Asia Minor. Other peoples such as the Elamites, represent similar offshoots of the fermenting culture of the region. The Hebrews were probably a small and unimportant group, settled close round Jerusalem, until a few centuries before the Christian Era. They then assimilated the culture of the more powerful nations which crossed and recrossed their territory. The Persians were, as we saw, a branch of the Aryan family which slowly advanced between 1500 and 700 B.C., and then inherited the empire of dying Babylon. The most interesting, and one of the most recently discovered, of these older civilisations, was the AEgean. Its chief centre was Crete, but it spread over many of the neighbouring islands. Its art and its script are so distinctive that we must recognise it as a native development, not a transplantation of Egyptian culture. Its ruins show it gradually emerging from the Neolithic stage about 4000 B.C., when Egyptian commerce was well developed in its seas. Somewhere about 2500 B.C. the whole of the islands seem to have been brought under the Cretan monarchy, and the concentration of wealth and power led to a remarkable artistic development, on native lines. We find in Crete the remains of splendid palaces, with advanced sanitary systems and a great luxuriance of ornamentation. It was this civilisation which founded the centre at Mycenae, on the Greek mainland, about the middle of the second millennium B.C. But our inquiry into the origin of European civilisation does not demand any extensive description of the AEgean culture and its Mycenaean offshoot. It was utterly destroyed between 1500 and 1000 B.C., and this was probably done by the Aryan ancestors of the later Greeks or Hellenes. About the time when one branch of the Aryans was descending upon India and another preparing to rival decaying Babylonia, the third branch overran Europe. It seems to have been a branch of these that swept down the Greek peninsula, and crossed the sea to sack and destroy the centres of AEgean culture. Another branch poured down the Italian peninsula; another settled in the region of the Baltic, and would prove the source of the Germanic nations; another, the Celtic, advanced to the west of Europe. The mingling of this semi-barbaric population with the earlier inhabitants provided the material of the nations of modern Europe. Our last page in the story of the earth must be a short account of its civilisation. The first branch to become civilised, and to carry culture to a greater height than the older nations had ever done, was the Hellenes. There is no need for us to speculate on the "genius" of the Hellenes, or even to enlarge on the natural advantages of the lower part of the peninsula which they occupied. A glance at the map will explain why European civilisation began in Greece. The Hellenes had penetrated the region in which there was constant contact with all the varied cultures of the older world. Although they destroyed the AEgean culture, they could not live amidst its ruins without receiving some influence. Then the traders of Phoenicia, triumphing in the fall of their AEgean rivals, brought the great pacific cultural influence of commerce to bear on them. After some hundreds of years of internal trouble, barbaric quarrels, and fresh arrivals from the north, Greece began to wear an aspect of civilisation. Many of the Greeks passed to Asia Minor, as they increased, and, freed from the despotism of tradition, in living contact with the luxury and culture of Persia, which had advanced as far as Europe, they evolved the fine civilisation of the Greek colonies, and reacted on the motherland. Finally, there came the heroic struggle against the Persian invaders, and from the ashes of their early civilisation arose the marble city which will never die in the memory of Europe. The Romans had meantime been advancing. We may neglect the older Italian culture, as it had far less to do with the making of Italy and Europe than the influence of the east. By about 500 B.C. Rome was a small kingdom with a primitive civilisation, busy in subduing the neighbouring tribes who threatened its security, and unconsciously gathering the seeds of culture which some of them contained. By about 300 B.C. the vigour of the Romans had united all the tribes of Italy in a powerful republic, and wealth began to accumulate at Rome. Not far to the east was the glittering civilisation of Greece; to the south was Carthage, a busy centre of commerce, navigation, and art; and from the Mediterranean came processions of ships bringing stimulating fragments and stories of the hoary culture of the east. Within another two hundred years Rome annihilated Carthage, paralysed and overran Greece, and sent its legions over the Asiatic provinces of the older empires. By the beginning of the Christian Era all that remained of the culture of the old world was gathered in Rome. All the philosophies of Greece, all the religions of Persia and Judea and Egypt, all the luxuries and vices of the east, found a home in it. Every stream of culture that had started from the later and higher Neolithic age had ended in Rome. And in the meantime Rome had begun to disseminate its heritage over Europe. Its legions poured over Spain and Gaul and Germany and Britain. Its administrators and judges and teachers followed the eagles, and set up schools and law-courts and theatres and baths and temples. It flung broad roads to the north of Britain and the banks of the Rhine and Danube. Under the shelter of the "Roman Peace" the peoples of Europe could spare men from the plough and the sword for the cultivation of art and letters. The civilisations of Britain, France, Germany, Spain, North Africa, and Italy were ushered into the calendar of mankind, and were ready to bear the burden when the mighty city on the Tiber let the sceptre fall from its enfeebled hands. Rome fell. The more accurate historians of our time correct the old legend of death from senile decay or from the effect of dissipation. Races of men, like races of animals, do not die; they are killed. The physical deterioration of the citizens of Rome was a small matter in its fall. Fiscal and imperial blunders loosed the frame of its empire. The resources were still there, but there was none to organise and unify them. The imperial system--or chaos--ruined Rome. And just when the demoralisation was greatest, and the Teutonic tribes at the frontiers were most numerous and powerful, an accident shook the system. A fierce and numerous people from Asia, the Huns, wandered into Europe, threw themselves on the Teutonic tribes, and precipitated these tribes upon the Empire. A Diocletian might still have saved the Empire, but there was none to guide it. The northern barbarians trod its civilisation underfoot, and Europe passed into the Dark Ages. One more application of the evolutionary principle, and we close the story. The "barbarians"--the Goths and Vandals and their Germanic cousins--were barbaric only in comparison with the art and letters of Rome. They had law, polity, and ideals. European civilisation owes elements to them, as well as to Rome. To say simply that the barbarians destroyed the institutions of Rome is no adequate explanation of the Dark Ages. Let us see rather how the Dark Ages were enlightened. It is now fully recognised that the reawakening of Europe in the twelfth and thirteenth centuries was very largely due to a fresh culture-contact with the older civilisations. The Arabs had, on becoming civilised, learned from the Nestorians, who had been driven out of the Greek world for their heresies, the ancient culture of Greece. They enshrined it in a brilliant civilisation which it inspired them to establish. By the ninth century this civilisation was exhibited in Spain by its Moorish conquerors, and, as its splendour increased, it attracted the attention of Europe. Some Christian scholars visited Spain, as time went on, but the Jews were the great intermediaries in disseminating its culture in Europe. There is now no question about the fact that the rebirth of positive learning, especially of science, in Europe was very largely due to the literature of the Moors, and their luxury and splendour gave an impulse to European art. Europe entered upon the remarkable intellectual period known as Scholasticism. Besides this stimulus, it must be remembered, the scholars of Europe had at least a certain number of old Latin writers whose works had survived the general wreck of culture. In the fifteenth century the awakening of Europe was completed. The Turks took Constantinople, and drove large numbers of Greek scholars to Italy. Out of this catastrophe issued the great Renaissance, or rebirth, of art, science, and letters in Italy, and then in France, Germany, and England. In the new intellectual ferment there appeared the great artists, great thinkers and inventors, and great navigators who led the race to fresh heights. The invention of printing alone would almost have changed the face of Europe. But it was accompanied by a hundred other inventions and discoveries, by great liberating and stimulating movements like the Reformation, by the growth of free and wealthy cities, and by the extension of peace over larger areas, and the concentration of wealth and encouragement of art which the growth and settlement of the chief European powers involved. Europe entered upon the phase of evolution which we call modern times. ***** The future of humanity cannot be seen even darkly, as in a glass. No forecast that aspires beyond the immediate future is worth considering seriously. If it be a forecast of material progress, it is rendered worthless by the obvious consideration that if we knew what the future will do, we would do it ourselves. If it is a forecast of intellectual and social evolution, it is inevitably coloured by the intellectual or social convictions of the prophet. I therefore abstain wholly from carrying the story of evolution beyond realities. But I would add two general considerations which may enable a reflective reader to answer certain questions that will arise in his mind at the close of this survey of the story of evolution. Are we evolving to-day? Is man the last word of evolution? These are amongst the commonest questions put to me. Whether man is or is not the last word of evolution is merely a verbal quibble. Now that language is invented, and things have names, one may say that the name "man" will cling to the highest and most progressive animal on earth, no matter how much he may rise above the man of to-day. But if the question is whether he WILL rise far above the civilisation of to-day, we can, in my opinion, give a confident answer. There is no law of evolution, but there is a fact of evolution. Ten million years ago the highest animal on the earth was a reptile, or, at the most, a low, rat-like marsupial. The authorities tell us that, unless some cosmic accident intervene, the earth will remain habitable by man for at least ten million years. It is safe to conclude that the man of that remote age will be lifted above the man of to-day as much as we transcend the reptile in intelligence and emotion. It is most probable that this is a quite inadequate expression of the future advance. We are not only evolving, but evolving more rapidly than living thing ever did before. The pace increases every century. A calm and critical review of our development inspires a conviction that a few centuries will bring about the realisation of the highest dream that ever haunted the mind of the prophet. What splendours lie beyond that, the most soaring imagination cannot have the dimmest perception. And the last word must meet an anxiety that arises out of this very confidence. Darwin was right. It is--not exclusively, but mainly--the struggle for life that has begotten higher types. Must every step of future progress be won by fresh and sustained struggle? At least we may say that the notion that progress in the future depends, as in the past, upon the pitting of flesh against flesh, and tooth against tooth, is a deplorable illusion. Such physical struggle is indeed necessary to evolve and maintain a type fit for the struggle. But a new thing has come into the story of the earth--wisdom and fine emotion. The processes which begot animal types in the past may be superseded; perhaps must be superseded. The battle of the future lies between wit and wit, art and art, generosity and generosity; and a great struggle and rivalry may proceed that will carry the distinctive powers of man to undreamed-of heights, yet be wholly innocent of the passion-lit, blood-stained conflict that has hitherto been the instrument of progress. 
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26260	----	ALSO BY _CLARENCE DAY_ THE CROW'S NEST THOUGHTS WITHOUT WORDS GOD AND MY FATHER IN THE GREEN MOUNTAIN COUNTRY SCENES FROM THE MESOZOIC LIFE WITH FATHER THIS SIMIAN _WORLD_ _by_ CLARENCE DAY _With Illustrations by the Author_ _New York & London_ ALFRED·A·KNOPF 1936 COPYRIGHT 1920, BY CLARENCE DAY _All rights reserved. No part of this book may be reproduced in any form without permission in writing from the publisher, except by a reviewer who may quote brief passages in a review to be printed in a magazine or newspaper._ _Published May 22, 1920_ _Reprinted Nine Times_ _Eleventh Printing, March, 1936_ _Manufactured in the United States of America_ "How I hate the man who talks about the 'brute creation,' with an ugly emphasis on _brute_.... As for me, I am proud of my close kinship with other animals. I take a jealous pride in my Simian ancestry. I like to think that I was once a magnificent hairy fellow living in the trees, and that my frame has come down through geological time via sea jelly and worms and Amphioxus, Fish, Dinosaurs, and Apes. Who would exchange these for the pallid couple in the Garden of Eden?" W. N. P. BARBELLION. _THIS SIMIAN WORLD_ _ONE_ Last Sunday, Potter took me out driving along upper Broadway, where those long rows of tall new apartment houses were built a few years ago. It was a mild afternoon and great crowds of people were out. Sunday afternoon crowds. They were not going anywhere,--they were just strolling up and down, staring at each other, and talking. There were thousands and thousands of them. "Awful, aren't they!" said Potter. I didn't know what he meant. When he added, "Why, these crowds," I turned and asked, "Why, what about them?" I wasn't sure whether he had an idea or a headache. "Other creatures don't do it," he replied, with a discouraged expression. "Are any other beings ever found in such masses, but vermin? Aimless, staring, vacant-minded,--look at them! I can get no sense whatever of individual worth, or of value in men as a race, when I see them like this. It makes one almost despair of civilization." I thought this over for awhile, to get in touch with his attitude. I myself feel differently at different times about us human-beings: sometimes I get pretty indignant when we are attacked (for there is altogether too much abuse of us by spectator philosophers) and yet at other times I too feel like a spectator, an alien: but even then I had never felt so alien or despairing as Potter. I cast about for the probable cause of our difference. "Let's remember," I said, "it's a simian civilization." Potter was staring disgustedly at some vaudeville sign-boards. "Yes," I said, "those for example are distinctively simian. Why should you feel disappointment at something inevitable?" And I went on to argue that it wasn't as though we were descended from eagles for instance, instead of (broadly speaking) from ape-like or monkeyish beings. Being of simian stock, we had simian traits. Our development naturally bore the marks of our origin. If we had inherited our dispositions from eagles we should have loathed vaudeville. But as cousins of the Bandarlog, we loved it. What could you expect? [Illustration: Descended from eagles] _TWO_ If we had been made directly from clay, the way it says in the Bible, and had therefore inherited no intermediate characteristics,--if a god, or some principle of growth, had gone that way to work with us, he or it might have molded us into much more splendid forms. But considering our simian descent, it has done very well. The only people who are disappointed in us are those who still believe that clay story. Or who--unconsciously--still let it color their thinking. * * * * * There certainly seems to be a power at work in the world, by virtue of which every living thing grows and develops. And it tends toward splendor. Seeds become trees, and weak little nations grow great. But the push or the force that is doing this, the yeast as it were, has to work in and on certain definite kinds of material. Because this yeast is in us, there may be great and undreamed of possibilities awaiting mankind; but because of our line of descent there are also queer limitations. [Illustration: Strange forgotten dynasties] _THREE_ In those distant invisible epochs before men existed, before even the proud missing link strutted around through the woods (little realizing how we his greatgrandsons would smile wryly at him, much as our own descendants may shudder at us, ages hence) the various animals were desperately competing for power. They couldn't or didn't live as equals. Certain groups sought the headship. Many strange forgotten dynasties rose, met defiance, and fell. In the end it was our ancestors who won, and became simian kings, and bequeathed a whole planet to us--and have never been thanked for it. No monument has been raised to the memory of those first hairy conquerors; yet had they not fought well and wisely in those far-off times, some other race would have been masters, and kept us in cages, or shot us for sport in the forests while they ruled the world. * * * * * So Potter and I, developing this train of thought, began to imagine we had lived many ages ago, and somehow or other had alighted here from some older planet. Familiar with the ways of evolution elsewhere in the universe, we naturally should have wondered what course it would take on this earth. "Even in this out-of-the-way corner of the Cosmos," we might have reflected, "and on this tiny star, it may be of interest to consider the trend of events." We should have tried to appraise the different species as they wandered around, each with its own set of good and bad characteristics. Which group, we'd have wondered, would ever contrive to rule all the rest? And how great a development could they attain to thereafter? _FOUR_ If we had landed here after the great saurians had been swept from the scene, we might first have considered the lemurs or apes. They had hands. Aesthetically viewed, the poor simians were simply grotesque; but travelers who knew other planets might have known what beauty may spring from an uncouth beginning in this magic universe. Still--those frowzy, unlovely hordes of apes and monkeys were so completely lacking in signs of kingship; they were so flighty, too, in their ways, and had so little purpose, and so much love for absurd and idle chatter, that they would have struck us, we thought, as unlikely material. Such traits, we should have reminded ourselves, persist. They are not easily left behind, even after long stages; and they form a terrible obstacle to all high advancement. _FIVE_ The bees or the ants might have seemed to us more promising. Their smallness of size was not necessarily too much of a handicap. They could have made poison their weapon for the subjugation of rivals. And in these orderly insects there was obviously a capacity for labor, and co-operative labor at that, which could carry them far. We all know that they have a marked genius: great gifts of their own. In a civilization of super-ants or bees, there would have been no problem of the hungry unemployed, no poverty, no unstable government, no riots, no strikes for short hours, no derision of eugenics, no thieves, perhaps no crime at all. Ants are good citizens: they place group interests first. But they carry it so far, they have few or no political rights. An ant doesn't have the vote, apparently: he just has his duties. This quality may have something to do with their having group wars. The egotism of their individual spirits is allowed scant expression, so the egotism of the group is extremely ferocious and active. Is this one of the reasons why ants fight so much? They go in for State Socialism, yes, but they are not internationalists. And ants commit atrocities in and after their battles that are--I wish I could truly say--inhuman. But conversely, ants are absolutely unselfish within the community. They are skilful. Ingenious. Their nests and buildings are relatively larger than man's. The scientists speak of their paved streets, vaulted halls, their hundreds of different domesticated animals, their pluck and intelligence, their individual initiative, their chaste and industrious lives. Darwin said the ant's brain was "one of the most marvelous atoms in the world, perhaps more so than the brain of man"--yes, of present-day man, who for thousands and thousands of years has had so much more chance to develop his brain.... A thoughtful observer would have weighed all these excellent qualities. When we think of these creatures as little men (which is all wrong of course) we see they have their faults. To our eyes they seem too orderly, for instance. Repressively so. Their ways are more fixed than those of the old Egyptians, and their industry is painful to think of, it's hyper-Chinese. But we must remember this is a simian comment. The instincts of the species that you and I belong to are of an opposite kind; and that makes it hard for us to judge ants fairly. But we and the ants are alike in one matter: the strong love of property. And instead of merely struggling with Nature for it, they also fight other ants. The custom of plunder seems to be a part of most of their wars. This has gone on for ages among them, and continues today. Raids, ferocious combats, and loot are part of an ant's regular life. Ant reformers, if there were any, might lay this to their property sense, and talk of abolishing property as a cure for the evil. But that would not help for long unless they could abolish the love of it. Ants seem to care even more for property than we do ourselves. We men are inclined to ease up a little when we have all we need. But it is not so with ants: they can't bear to stop: they keep right on working. This means that ants do not contemplate: they heed nothing outside of their own little rounds. It is almost as though their fondness for labor had closed fast their minds. Conceivably they might have developed inquiring minds. But this would have run against their strongest instincts. The ant is knowing and wise; but he doesn't know enough to take a vacation. The worshipper of energy is too physically energetic to see that he cannot explore certain higher fields until he is still. Even if such a race had somehow achieved self-consciousness and reason, would they have been able therewith to rule their instincts, or to stop work long enough to examine themselves, or the universe, or to dream of any noble development? Probably not. Reason is seldom or never the ruler: it is the servant of instinct. It would therefore have told the ants that incessant toil was useful and good. "Toil has brought you up from the ruck of things," Reason would have plausibly said. "It's by virtue of feverish toil that you have become what you are. Being endlessly industrious is the best road--for you--to the heights." And, self-reassured, they would then have had orgies of work; and thus, by devoted exertion, have blocked their advancement. Work, and order and gain would have withered their souls. _SIX_ Let us take the great cats. They are free from this talent for slave-hood. Stately beasts like the lion have more independence of mind than the ants,--and a self-respect, we may note, unknown to primates. Or consider the leopards, with hearts that no tyrant could master. What fearless and resolute leopard-men they could have fathered! How magnificently such a civilization would have made its force tell! A race of civilized beings descended from these great cats would have been rich in hermits and solitary thinkers. The recluse would not have been stigmatized as peculiar, as he is by us simians. They would not have been a credulous people, or easily religious. False prophets and swindlers would have found few dupes. And what generals they would have made! what consummate politicians! Don't imagine them as a collection of tigers walking around on their hind-legs. They would have only been like tigers in the sense that we men are like monkeys. Their development in appearance and character would have been quite transforming. Instead of the small flat head of the tiger, they would have had clear smooth brows; and those who were not bald would have had neatly parted hair--perhaps striped. Their mouths would have been smaller and more sensitive: their faces most dignified. Where now they express chiefly savageness, they would have expressed fire and grace. They would have been courteous and suave. No vulgar crowding would have occurred on the streets of their cities. No mobs. No ignominious subway-jams. Imagine a cultivated coterie of such men and women, at a ball, dancing. How few of us humans are graceful. They would have all been Pavlovas. * * * * * Like ants and bees, the cat race is nervous. Their temperaments are high-strung. They would never have become as poised or as placid as--say--super-cows. Yet they would have had less insanity, probably, than we. Monkeys' (and elephants') minds seem precariously balanced, unstable. The great cats are saner. They are intense, they would have needed sanitariums: but fewer asylums. And their asylums would have been not for weak-minded souls, but for furies. They would have been strong at slander. They would have been far more violent than we, in their hates, and they would have had fewer friendships. Yet they might not have been any poorer in real friendships than we. The real friendships among men are so rare that when they occur they are famous. Friends as loyal as Damon and Pythias were, are exceptions. Good fellowship is common, but unchanging affection is not. We like those who like us, as a rule, and dislike those who don't. Most of our ties have no better footing than that; and those who have many such ties are called warm-hearted. * * * * * The super-cat-men would have rated cleanliness higher. Some of us primates have learned to keep ourselves clean, but it's no large proportion; and even the cleanest of us see no grandeur in soap-manufacturing, and we don't look to manicures and plumbers for social prestige. A feline race would have honored such occupations. J. de Courcy Tiger would have felt that nothing _but_ making soap, or being a plumber, was compatible with a high social position; and the rich Vera Pantherbilt would have deigned to dine only with manicures. None but the lowest dregs of such a race would have been lawyers spending their span of life on this mysterious earth studying the long dusty records of dead and gone quarrels. We simians naturally admire a profession full of wrangle and chatter. But that is a monkeyish way of deciding disputes, not a feline. We fight best in armies, gregariously, where the risk is reduced; but we disapprove usually of murderers, and of almost all private combat. With the great cats, it would have been just the other way round. (Lions and leopards fight each other singly, not in bands, as do monkeys.) As a matter of fact, few of us delight in really serious fighting. We do love to bicker; and we box and knock each other around, to exhibit our strength; but few normal simians are keen about bloodshed and killing; we do it in war only because of patriotism, revenge, duty, glory. A feline civilization would have cared nothing for duty or glory, but they would have taken a far higher pleasure in gore. If a planet of super-cat-men could look down upon ours, they would not know which to think was the most amazing: the way we tamely live, five million or so in a city, with only a few police to keep us quiet, while we commit only one or two murders a day, and hardly have a respectable number of brawls; or the way great armies of us are trained to fight,--not liking it much, and yet doing more killing in war-time and shedding more blood than even the fiercest lion on his cruelest days. Which would perplex a gentlemanly super-cat spectator the more, our habits of wholesale slaughter in the field, or our spiritless making a fetish of "order," at home? * * * * * It is fair to judge peoples by the rights they will sacrifice most for. Super-cat-men would have been outraged, had their right of personal combat been questioned. The simian submits with odd readiness to the loss of this privilege. What outrages him is to make him stop wagging his tongue. He becomes most excited and passionate about the right of free speech, even going so far in his emotion as to declare it is sacred. He looks upon other creatures pityingly because they are dumb. If one of his own children is born dumb, he counts it a tragedy. Even that mere hesitation in speech, known as stammering, he deems a misfortune. So precious to a simian is the privilege of making sounds with his tongue, that when he wishes to punish severely those men he calls criminals, he forbids them to chatter, and forces them by threats to be silent. It is felt that this punishment is entirely too cruel however, and that even the worst offenders should be allowed to talk part of each day. Whatever a simian does, there must always be some talking about it. He can't even make peace without a kind of chatter called a peace conference. Super-cats would not have had to "make" peace: they would have just walked off and stopped fighting. * * * * * In a world of super-cat-men, I suppose there would have been fewer sailors; and people would have cared less for seaside resorts, or for swimming. Cats hate getting wet, so men descended from them might have hated it. They would have felt that even going in wading was a sign of great hardihood, and only the most daring young fellows, showing off, would have done it. Among them there would have been no anti-vivisection societies: No Young Cats Christian Associations or Red Cross work: No vegetarians: No early closing laws: Much more hunting and trapping: No riding to hounds; that's pure simian. Just think how it would have entranced the old-time monkeys to foresee such a game! A game where they'd all prance off on captured horses, tearing pell-mell through the woods in gay red coats, attended by yelping packs of servant-dogs. It is excellent sport--but how cats would scorn to hunt in that way! They would not have knighted explorers--they would have all been explorers. * * * * * Imagine that you are strolling through a super-cat city at night. Over yonder is the business quarter, its evening shops blazing with jewels. The great stock-yards lie to the east where you hear those sad sounds: that low mooing as of innumerable herds, waiting slaughter. Beyond lie the silent aquariums and the crates of fresh mice. (They raise mice instead of hens in the country, in Super-cat Land.) To the west is a beautiful but weirdly bacchanalian park, with long groves of catnip, where young super-cats have their fling, and where a few crazed catnip addicts live on till they die, unable to break off their strangely undignified orgies. And here where you stand is the sumptuous residence district. Houses with spacious grounds everywhere: no densely-packed buildings. The streets have been swept up--or lapped up--until they are spotless. Not a scrap of paper is lying around anywhere: no rubbish, no dust. Few of the pavements are left bare, as ours are, and those few are polished: the rest have deep soft velvet carpets. No footfalls are heard. [Illustration: Punctilious, haughty, inflammable] There are no lights in these streets, though these people are abroad much at night. All you see are stars overhead and the glowing eyes of cat ladies, of lithe silken ladies who pass you, or of stiff-whiskered men. Beware of those men and the gleam of their split-pupiled stare. They are haughty, punctilious, inflammable: self-absorbed too, however. They will probably not even notice you; but if they do, you are lost. They take offense in a flash, abhor strangers, despise hospitality, and would think nothing of killing you or me on their way home to dinner. Follow one of them. Enter this house. Ah what splendor! No servants, though a few abject monkeys wait at the back-doors, and submissively run little errands. But of course they are never let inside: they would seem out of place. Gorgeous couches, rich colors, silken walls, an oriental magnificence. In here is the ballroom. But wait: what is this in the corner? A large triumphal statue--of a cat overcoming a dog. And look at this dining-room, its exquisite appointments, its daintiness: faucets for hot and cold milk in the pantry, and a gold bowl of cream. Some one is entering. Hush! If I could but describe her! Languorous, slender and passionate. Sleepy eyes that see everything. An indolent purposeful step. An unimaginable grace. If you were _her_ lover, my boy, you would learn how fierce love can be, how capricious and sudden, how hostile, how ecstatic, how violent! * * * * * Think what the state of the arts would have been in such cities. They would have had few comedies on their stage; no farces. Cats care little for fun. In the circus, superlative acrobats. No clowns. [Illustration: One of their poets] In drama and singing they would have surpassed us probably. Even in the stage of arrested development as mere animals, in which we see cats, they wail with a passionate intensity at night in our yards. Imagine how a Caruso descended from such beings would sing. In literature they would not have begged for happy endings. They would have been personally more self-assured than we, far freer of cheap imitativeness of each other in manners and art, and hence more original in art; more clearly aware of what they really desired, not cringingly watchful of what was expected of them; less widely observant perhaps, more deeply thoughtful. Their artists would have produced less however, even though they felt more. A super-cat artist would have valued the pictures he drew for their effects on himself; he wouldn't have cared a rap whether anyone else saw them or not. He would not have bothered, usually, to give any form to his conceptions. Simply to have had the sensation would have for him been enough. But since simians love to be noticed, it does not content them to have a conception; they must wrestle with it until it takes a form in which others can see it. They doom the artistic impulse to toil with its nose to the grindstone, until their idea is expressed in a book or a statue. Are they right? I have doubts. The artistic impulse seems not to wish to produce finished work. It certainly deserts us half-way, after the idea is born; and if we go on, art is labor. With the cats, art is joy. * * * * * But the dominant characteristic of this fine race is cunning. And hence I think it would have been through their craftiness, chiefly, that they would have felt the impulse to study, and the wish to advance. Craft is a cat's delight: craft they never can have too much of. So it would have been from one triumph of cunning to another that they would have marched. That would have been the greatest driving force of their civilization. This would have meant great progress in invention and science--or in some fields of science, the economic for instance. But it would have retarded them in others. Craft studies the world calculatingly, from without, instead of understandingly from within. Especially would it have cheapened the feline philosophies; for not simply how to know but how to circumvent the universe would have been their desire. Mankind's curiosity is disinterested; it seems purer by contrast. That is to say, made as we are, it seems purer to us. What we call disinterested, however, super-cats might call aimless. (Aimlessness is one of the regular simian traits.) I don't mean to be prejudiced in favor of the simian side. Curiosity may be as debasing, I grant you, as craft. And craft might turn into artifices of a kind which would be noble and fine. Just as the ignorant and fitful curiosity of some little monkey is hardly to be compared to the astronomer's magnificent search, so the craft and cunning we see in our pussies would bear small relation to the high-minded planning of some ruler of the race we are imagining. And yet--craft _is_ self-defeating in the end. Transmute it into its finest possible form, let it be as subtle and civilized as you please, as yearning and noble, as enlightened, it still sets itself over against the wholeness of things; its rôle is that of the part at war with the whole. Milton's Lucifer had the mind of a fine super-cat. That craft may defeat itself in the end, however, is not the real point. That doesn't explain why the lions aren't ruling the planet. The trouble is, it would defeat itself in the beginning. It would have too bitterly stressed the struggle for existence. Conflict and struggle make civilizations virile, but they do not by themselves make civilizations. Mutual aid and support are needed for that. There the felines are lacking. They do not co-operate well; they have small group-devotion. Their lordliness, their strong self-regard, and their coolness of heart, have somehow thwarted the chance of their racial progress. _SEVEN_ There are many other beasts that one might once have thought had a chance. Some, like horses and deer, were not bold enough; or were stupid, like buffaloes. Some had over-trustful characters, like the seals; or exploitable characters, like cows, and chickens, and sheep. Such creatures sentence themselves to be captives, by their lack of ambition. Dogs? They have more spirit. But they have lost their chance of kingship through worshipping us. The dog's finer qualities can't be praised too warmly; there is a purity about his devotion which makes mere men feel speechless: but with all love for dogs, one must grant they are vassals, not rulers. They are too parasitic--the one willing servant class of the world. And we have betrayed them by making under-simians of them. We have taught them some of our own ways of behaving, and frowned upon theirs. Loving us, they let us stop their developing in tune with their natures; and they've patiently tried ever since to adopt ways of ours. They have done it, too; but of course they can't get far: it's not their own road. Dogs have more love than integrity. They've been true to us, yes, but they haven't been true to themselves. Pigs? The pig is remarkably intelligent and brave,--but he's gross; and grossness delays one's achievement, it takes so much time. The snake too, though wise, has a way of eating himself into stupors. If super-snake-men had had banquets they would have been too vast to describe. Each little snake family could have eaten a herd of cattle at Christmas. Goats, then? Bears or turtles? Wolves, whales, crows? Each had brains and pride, and would have been glad to rule the world if they could; but each had their defects, and their weaknesses for such a position. The elephant? Ah! Evolution has had its tragedies, hasn't it, as well as its triumphs; and well should the elephant know it. He had the best chance of all. Wiser even than the lion, or the wisest of apes, his wisdom furthermore was benign where theirs was sinister. Consider his dignity, his poise and skill. He was plastic, too. He had learned to eat many foods and endure many climates. Once, some say, this race explored the globe. Their bones are found everywhere, in South America even; so the elephants' Columbus may have found some road here before ours. They are cosmopolitans, these suave and well-bred beings. They have rich emotional natures, long memories, loyalty; they are steady and sure; and not narrow, not self-absorbed, for they seem interested in everything. What was it then, that put them out of the race? Could it have been a quite natural belief that they had already won? And when they saw that they hadn't, and that the monkey-men were getting ahead, were they too great-minded and decent to exterminate their puny rivals? It may have been their tolerance and patience that betrayed them. They wait too long before they resent an imposition or insult. Just as ants are too energetic and cats too shrewd for their own highest good, so the elephants suffer from too much patience. Their exhibitions of it may seem superb,--such power and such restraint, combined, are noble,--but a quality carried to excess defeats itself. Kings who won't lift their scepters must yield in the end; and, the worst of it is, to upstarts who snatch at their crowns. * * * * * I fancy the elephants would have been gentler masters than we: more live-and-let-live in allowing other species to stay here. Our way is to kill good and bad, male and female and babies, till the few last survivors lie hidden away from our guns. All species must surrender unconditionally--those are our terms--and come and live in barns alongside us; or on us, as parasites. The creatures that want to live a life of their own, we call wild. If wild, then no matter how harmless we treat them as outlaws, and those of us who are specially well brought up shoot them for fun. Some might be our friends. We don't wish it. We keep them all terrorized. When one of us conquering monkey-men enters the woods, most animals that scent him slink away, or race off in a panic. It is not that we have planned this deliberately: but they know what we're like. Race by race they have been slaughtered. Soon all will be gone. We give neither freedom nor life-room to those we defeat. If we had been as strong as the elephants, we might have been kinder. When great power comes naturally to people, it is used more urbanely. We use it as parvenus do, because that's what we are. The elephant, being born to it, is easy-going, confident, tolerant. He would have been a more humane king. * * * * * A race descended from elephants would have had to build on a large scale. Imagine a crowd of huge, wrinkled, slow-moving elephant-men getting into a vast elephant omnibus. And would they have ever tried airships? The elephant is stupid when it comes to learning how to use tools. So are all other species except our own. Isn't it strange? A tool, in the most primitive sense, is any object, lying around, that can obviously be used as an instrument for this or that purpose. Many creatures use objects as _materials_, as birds use twigs for nests. But the step that no animal takes is learning freely to use things as instruments. When an elephant plucks off a branch and swishes his flanks, and thus keeps away insects, he is using a tool. But he does it only by a vague and haphazard association of ideas. If he once became a conscious user of tools he would of course go much further. We ourselves, who are so good at it now, were slow enough in beginning. Think of the long epochs that passed before it entered our heads. And all that while the contest for leadership blindly went on, without any species making use of this obvious aid. The lesson to be learned was simple: the reward was the rule of a planet. Yet only one species, our own, has ever had that much brains. It makes you wonder what other obvious lessons may still be unlearned. * * * * * It is not necessarily stupid however, to fail to use tools. To use tools involves using reason, instead of sticking to instinct. Now, sticking to instinct has its disadvantages, but so has using reason. Whichever faculty you use, the other atrophies, and partly deserts you. We are trying to use both. But we still don't know which has the more value. * * * * * A sudden vision comes to me of one of the first far-away ape-men who tried to use reason instead of instinct as a guide for his conduct. I imagine him, perched in his tree, torn between those two voices, wailing loudly at night by a river, in his puzzled distress. My poor far-off brother! [Illustration: The First Thinker.] _EIGHT_ We have been considering which species was on the whole most finely equipped to be rulers, and thereafter achieve a high civilization; but that wasn't the problem. The real problem was which would _do_ it:--a different matter. To do it there was need of a species that had at least these two qualities: some quenchless desire, to urge them on and on; and also adaptability of a thousand kinds to their environment. The rhinoceros cares little for adaptability. He slogs through the world. But we! we are experts. Adaptability is what we depend on. We talk of our mastery of nature, which sounds very grand; but the fact is we respectfully adapt ourselves first, to her ways. "We attain no power over nature till we learn natural laws, and our lordship depends on the adroitness with which we learn and conform." Adroitness however is merely an ability to win; back of it there must be some spur to make us use our adroitness. Why don't we all die or give up when we're sick of the world? Because the love of life is reënforced, in most energized beings, by some longing that pushes them forward, in defeat and in darkness. All creatures wish to live, and to perpetuate their species, of course; but those two wishes alone evidently do not carry any race far. In addition to these, a race, to be great, needs some hunger, some itch, to spur it up the hard path we lately have learned to call evolution. The love of toil in the ants, and of craft in cats, are examples (imaginary or not). What other such lust could exert great driving force? With us is it curiosity? endless interest in one's environment? Many animals have some curiosity, but "some" is not enough; and in but few is it one of the master passions. By a master passion, I mean a passion that is really your master: some appetite which habitually, day in, day out, makes its subjects forget fatigue or danger, and sacrifice their ease to its gratification. That is the kind of hold that curiosity has on the monkeys. _NINE_ Imagine a prehistoric prophet observing these beings, and forecasting what kind of civilizations their descendants would build. Anyone could have foreseen certain parts of the simians' history: could have guessed that their curiosity would unlock for them, one by one, nature's doors, and--idly--bestow on them stray bits of valuable knowledge: could have pictured them spreading inquiringly all over the globe, stumbling on their inventions--and idly passing on and forgetting them. To have to learn the same thing over and over again wastes the time of a race. But this is continually necessary, with simians, because of their disorder. "Disorder," a prophet would have sighed: "that is one of their handicaps; one that they will never get rid of, whatever it costs. Having so much curiosity makes a race scatter-brained. "Yes," he would have dismally continued, "it will be a queer mixture: these simians will attain to vast stores of knowledge, in time, that is plain. But after spending centuries groping to discover some art, in after-centuries they will now and then find it's forgotten. How incredible it would seem on other planets to hear of lost arts. "There is a strong streak of triviality in them, which you don't see in cats. They won't have fine enough characters to concentrate on the things of most weight. They will talk and think far more of trifles than of what is important. Even when they are reasonably civilized, this will be so. Great discoveries sometimes will fail to be heard of, because too much else is; and many will thus disappear, and these men will not know it."[1] [1] We did rescue Mendel's from the dust heap; but perhaps it was an exception. * * * * * Let me interrupt this lament to say a word for myself and my ancestors. It is easy to blame us as undiscriminating, but we are at least full of zest. And it's well to be interested, eagerly and intensely, in so many things, because there is often no knowing which may turn out important. We don't go around being interested on purpose, hoping to profit by it, but a profit may come. And anyway it is generous of us not to be too self-absorbed. Other creatures go to the other extreme to an amazing extent. They are ridiculously oblivious to what is going on. The smallest ant in the garden will ignore the largest woman who visits it. She is a huge and most dangerous super-mammoth in relation to him, and her tread shakes the earth; but he has no time to be bothered, investigating such-like phenomena. He won't even get out of her way. He has his work to do, hang it. Birds and squirrels have less of this glorious independence of spirit. They watch you closely--if you move around. But not if you keep still. In other words, they pay no more attention than they can help, even to mammoths. We of course observe everything, or try to. We could spend our lives looking on. Consider our museums for instance: they are a sign of our breed. It makes us smile to see birds, like the magpie, with a mania for this collecting--but only monkeyish beings could reverence museums as we do, and pile such heterogeneous trifles and quantities in them. Old furniture, egg-shells, watches, bits of stone.... And next door, a "menagerie." Though our victory over all other animals is now aeons old, we still bring home captives and exhibit them caged in our cities. And when a species dies out--or is crowded (by us) off the planet--we even collect the bones of the vanquished and show them like trophies. * * * * * Curiosity is a valuable trait. It will make the simians learn many things. But the curiosity of a simian is as excessive as the toil of an ant. Each simian will wish to know more than his head can hold, let alone ever deal with; and those whose minds are active will wish to know everything going. It would stretch a god's skull to accomplish such an ambition, yet simians won't like to think it's beyond their powers. Even small tradesmen and clerks, no matter how thrifty, will be eager to buy costly encyclopedias, or books of all knowledge. Almost every simian family, even the dullest, will think it is due to themselves to keep all knowledge handy. Their idea of a liberal education will therefore be a great hodge-podge; and he who narrows his field and digs deep will be viewed as an alien. If more than one man in a hundred should thus dare to concentrate, the ruinous effects of being a specialist will be sadly discussed. It may make a man exceptionally useful, they will have to admit; but still they will feel badly, and fear that civilization will suffer. * * * * * One of their curious educational ideas--but a natural one--will be shown in the efforts they will make to learn more than one "language." They will set their young to spending a decade or more of their lives in studying duplicate systems--whole systems--of chatter. Those who thus learn several different ways to say the same things, will command much respect, and those who learn many will be looked on with awe--by true simians. And persons without this accomplishment will be looked down on a little, and will actually feel quite apologetic about it themselves. Consider how enormously complicated a complete language must be, with its long and arbitrary vocabulary, its intricate system of sounds; the many forms that single words may take, especially if they are verbs; the rules of grammar, the sentence structure, the idioms, slang and inflections. Heavens, what a genius for tongues these simians have![2] Where another race, after the most frightful discord and pains, might have slowly constructed _one_ language before this earth grew cold, this race will create literally hundreds, each complete in itself, and many of them with quaint little systems of writing attached. And the owners of this linguistic gift are so humble about it, they will marvel at bees, for their hives, and at beavers' mere dams. [2] You remember what Kipling says in the Jungle Books, about how disgusted the quiet animals were with the Bandarlog, because they were eternally chattering, would never keep still. Well, this is the good side of it. * * * * * To return, however, to their fear of being too narrow, in going to the other extreme they will run to incredible lengths. Every civilized simian, every day of his life, in addition to whatever older facts he has picked up, will wish to know all the news of all the world. If he felt any true concern to know it, this would be rather fine of him: it would imply such a close solidarity on the part of this genus. (Such a close solidarity would seem crushing, to others; but that is another matter.) It won't be true concern, however, it will be merely a blind inherited instinct. He'll forget what he's read, the very next hour, or moment. Yet there he will faithfully sit, the ridiculous creature, reading of bombs in Spain or floods in Thibet, and especially insisting on all the news he can get of the kind our race loved when they scampered and fought in the forest, news that will stir his most primitive simian feelings,--wars, accidents, love affairs, and family quarrels. To feed himself with this largely purposeless provender, he will pay thousands of simians to be reporters of such events day and night; and they will report them on such a voluminous scale as to smother or obscure more significant news altogether. Great printed sheets will be read by every one every day; and even the laziest of this lazy race will not think it labor to perform this toil. They won't like to eat in the morning without their papers, such slaves they will be to this droll greed for knowing. They won't even think it is droll, it is so in their blood. Their swollen desire for investigating everything about them, including especially other people's affairs, will be quenchless. Few will feel that they really are "fully informed"; and all will give much of each day all their lives to the news. Books too will be used to slake this unappeasable thirst. They will actually hold books in deep reverence. Books! Bottled chatter! things that some other simian has formerly said. They will dress them in costly bindings, keep them under glass, and take an affecting pride in the number they read. Libraries,--store-houses of books,--will dot their world. The destruction of one will be a crime against civilization. (Meaning, again, a simian civilization.) Well, it is an offense to be sure--a barbaric offense. But so is defacing forever a beautiful landscape; and they won't even notice that sometimes; they won't shudder anyway, the way they instinctively do at the loss of a "library." * * * * * All this is inevitable and natural, and they cannot help it. There even are ways one can justify excesses like this. If their hunger for books ever seems indiscriminate to them when they themselves stop to examine it, they will have their excuses. They will argue that some bits of knowledge they once had thought futile, had later on come in most handy, in unthought of ways. True enough! For their scientists. But not for their average men: they will simply be like obstinate housekeepers who clog up their homes, preserving odd boxes and wrappings, and stray lengths of string, to exult if but one is of some trifling use ere they die. It will be in this spirit that simians will cherish their books, and pile them up everywhere into great indiscriminate mounds; and these mounds will seem signs of culture and sagacity to them. Those who know many facts will feel wise! They will despise those who don't. They will even believe, many of them, that knowledge is power. Unfortunate dupes of this saying will keep on reading, ambitiously, till they have stunned their native initiative, and made their thoughts weak; and will then wonder dazedly what in the world is the matter, and why the great power they were expecting to gain fails to appear. Again, if they ever forget what they read, they'll be worried. Those who _can_ forget--those with fresh eyes who have swept from their minds such facts as the exact month and day that their children were born, or the numbers on houses, or the names (the mere meaningless labels) of the people they meet,--will be urged to go live in sanitariums or see memory doctors! * * * * * By nature their itch is rather for knowing, than for understanding or thinking. Some of them will learn to think, doubtless, and even to concentrate, but their eagerness to acquire those accomplishments will not be strong or insistent. Creatures whose mainspring is curiosity will enjoy the accumulating of facts, far more than the pausing at times to reflect on those facts. If they do not reflect on them, of course they'll be slow to find out about the ideas and relationships lying behind them; and they will be curious about those ideas; so you would suppose they'd reflect. But deep thinking is painful. It means they must channel the spready rivers of their attention. That cannot be done without discipline and drills for the mind; and they will abhor doing that; their minds will work better when they are left free to run off at tangents. Compare them in this with other species. Each has its own kind of strength. To be compelled to be so quick-minded as the simians would be torture, to cows. Cows could dwell on one idea, week by week, without trying at all; but they'd all have brain-fever in an hour at a simian tea. A super-cow people would revel in long thoughtful books on abstruse philosophical subjects, and would sit up late reading them. Most of the ambitious simians who try it--out of pride--go to sleep. The typical simian brain is supremely distractable, and it's really too jumpy by nature to endure much reflection. Therefore many more of them will be well-informed than sagacious. This will result in their knowing most things far too soon, at too early a stage of civilization to use them aright. They will learn to make valuable explosives at a stage in their growth, when they will use them not only in industries, but for killing brave men. They will devise ways to mine coal efficiently, in enormous amounts, at a stage when they won't know enough to conserve it, and will waste their few stores. They will use up a lot of it in a simian habit[3] called travel. This will consist in queer little hurried runs over the globe, to see ten thousand things in the hope of thus filling their minds. [3] Even in a wild state, the monkey is restless and does not live in lairs. Their minds will be full enough. Their intelligence will be active and keen. It will have a constant tendency however to outstrip their wisdom. Their intelligence will enable them to build great industrial systems before they have the wisdom and goodness to run them aright. They will form greater political empires than they will have strength to guide. They will endlessly quarrel about which is the best scheme of government, without stopping to realize that learning to govern comes first. (The average simian will imagine he knows without learning.) The natural result will be industrial and political wars. In a world of unmanageable structures, wild smashes must come. _TEN_ Inventions will come so easily to simians (in comparison with all other creatures) and they will take such childish pleasure in monkeying around, making inventions, that their many devices will be more of a care than a comfort. In their homes a large part of their time will have to be spent keeping their numerous ingenuities in good working order--their elaborate bell-ringing arrangements, their locks and their clocks. In the field of science to be sure, this fertility in invention will lead to a long list of important and beautiful discoveries: telescopes and the calculus, radiographs, and the spectrum. Discoveries great enough, almost, to make angels of them. But here again their simian-ness will cheat them of half of their dues, for they will neglect great discoveries of the truest importance, and honor extravagantly those of less value and splendor if only they cater especially to simian traits. To consider examples: A discovery that helps them to talk, just to talk, more and more, will be hailed by these beings as one of the highest of triumphs. Talking to each other over wires will come in this class. The lightning when harnessed and tamed will be made to trot round, conveying the most trivial cacklings all day and night. Huge seas of talk of every sort and kind, in print, speech, and writing, will roll unceasingly over their civilized realms, involving an unbelievable waste in labor and time, and sapping the intelligence talk is supposed to upbuild. In a simian civilization, great halls will be erected for lectures, and great throngs will actually pay to go inside at night to hear some self-satisfied talk-maker chatter for hours. Almost any subject will do for a lecture, or talk; yet very few subjects will be counted important enough for the average man to do any _thinking_ on them, off by himself. In their futurist books they will dream of an even worse state, a more dreadful indulgence in communication than the one just described. This they'll hope to achieve by a system called mental telepathy. They will long to communicate wordlessly, mind impinging on mind, until all their minds are awash with messages every moment, and withdrawal from the stream is impossible anywhere on earth. This will foster the brotherhood of man. (Conglomerateness being their ideal.) Super-cats would have invented more barriers instead of more channels. Discoveries in surgery and medicine will also be over-praised. The reason will be that the race will so need these discoveries. Unlike the great cats, simians tend to undervalue the body. Having less self-respect, less proper regard for their egos, they care less than the cats do for the casing of the ego,--the body. The more civilized they grow the more they will let their bodies deteriorate. They will let their shoulders stoop, their lungs shrink, and their stomachs grow fat. No other species will be quite so deformed and distorted. Athletics they will watch, yes, but on the whole sparingly practise. Their snuffy old scholars will even be proud to decry them. Where once the simians swung high through forests, or scampered like deer, their descendants will plod around farms, or mince along city streets, moving constrictedly, slowly, their litheness half gone. They will think of Nature as "something to go out and look at." They will try to live wholly apart from her and forget they're her sons. Forget? They will even deny it, and declare themselves sons of God. In spite of her wonders they will regard Nature as somehow too humble to be the true parent of such prominent people as simians. They will lose all respect for the dignity of fair Mother Earth, and whisper to each other she is an evil and indecent old person. They will snatch at her gifts, pry irreverently into her mysteries, and ignore half the warnings they get from her about how to live. Ailments of every kind will abound among such folk, inevitably, and they will resort to extraordinary expedients in their search for relief. Although squeamish as a race about inflicting much pain in cold blood, they will systematically infect other animals with their own rank diseases, or cut out other animals' organs, or kill and dissect them, hoping thus to learn how to offset their neglect of themselves. Conditions among them will be such that this will really be necessary. Few besides impractical sentimentalists will therefore oppose it. But the idea will be to gain health by legerdemain, by a trick, instead of by taking the trouble to live healthy lives. Strange barrack-like buildings called hospitals will stand in their cities, where their trick-men, the surgeons, will slice them right open when ill; and thousands of zealous young pharmacists will mix little drugs, which thousands of wise-looking simians will firmly prescribe. Each generation will change its mind as to these drugs, and laugh at all former opinions; but each will use some of them, and each will feel assured that in this respect they know the last word. And, in obstinate blindness, this people will wag their poor heads, and attribute their diseases not to simian-ness but to civilization. The advantages that any man or race has, can sometimes be handicaps. Having hands, which so aids a race, for instance, can also be harmful. The simians will do so many things with their hands, it will be bad for their bodies. Instead of roaming far and wide over the country, getting vigorous exercise, they will use their hands to catch and tame horses, build carriages, motors, and then when they want a good outing they will "go for a ride," with their bodies slumped down, limp and sluggish, and losing their spring. Then too their brains will do harm, and great harm, to their bodies. The brain will give them such an advantage over all other animals that they will insensibly be led to rely too much on it, to give it too free a rein, and to find the mirrors in it too fascinating. This organ, this outgrowth, this new part of them, will grow over-active, and its many fears and fancies will naturally injure the body. The interadjustment is delicate and intimate, the strain is continuous. When the brain fails to act with the body, or, worse, works against it, the body will sicken no matter what cures doctors try. As in bodily self-respect, so in racial self-respect, they'll be wanting. They will have plenty of racial pride and prejudice, but that is not the same thing. That will make them angry when simians of one color mate with those of another. But a general deterioration in physique will cause much less excitement. They will _talk_ about improving the race--they will talk about everything--but they won't use their chances to _do_ it. Whenever a new discovery makes life less hard, for example, these heedless beings will seldom preserve this advantage, or use their new wealth to take more time thereafter for thought, or to gain health and strength or do anything else to make the race better. Instead, they will use the new ease just to increase in numbers; and they will keep on at this until misery once more has checked them. Life will then be as hard as ever, naturally, and the chance will be gone. They will have a proverb, "The poor ye have always with you,"--said by one who knew simians. Their ingenious minds will have an answer to this. They will argue it is well that life should be Spartan and hard, because of the discipline and its strengthening effects on the character. But the good effects of this sort of discipline will be mixed with sad wreckage. And only creatures incapable of disciplining themselves could thus argue. It is an odd expedient to get yourself into trouble just for discipline's sake. The fact is, however, the argument won't be sincere. When their nations grow so over-populous and their families so large it means misery, that will not be a sign of their having felt ready for discipline. It will be a sign of their not having practised it in their sexual lives. _ELEVEN_ The simians are always being stirred by desire and passion. It constantly excites them, constantly runs through their minds. Wild or tame, primitive or cultured, this is a brand of the breed. Other species have times and seasons for sexual matters, but the simian-folk are thus preoccupied all the year round. This super-abundance of desire is not necessarily good or bad, of itself. But to shape it for the best it will have to be studied--and faced. This they will not do. Some of them won't like to study it, deeming it bad--deeming it bad yet yielding constantly to it. Others will hesitate because they will deem it so sacred, or will secretly fear that study might show them it ought to be curbed. Meantime, this part of their nature will be coloring all their activities. It will beautify their arts, and erotically confuse their religions. It will lend a little interest to even their dull social functions. It will keep alive degrading social evils in all their great towns. Through these latter evils, too, their politics will be corrupted; especially their best and most democratic attempts at self-government. Self-government works best among those who have learned to self-govern. * * * * * In the far distant ages that lie before us what will be the result of this constant preoccupation with desire? Will it kill us or save us? Will this trait and our insatiable curiosity interact on each other? That might further eugenics. That might give us a better chance to breed finely than all other species. * * * * * We already owe a great deal to passion: more than men ever realize. Wasn't it Darwin who once even risked the conjecture that the vocal organs themselves were developed for sexual purposes, the object being to call or charm one's mate. Hence--perhaps--only animals that were continuously concerned with their matings would be at all likely to form an elaborate language. And without an elaborate language, growth is apt to be slow. If we owe this to passion, what follows? Does it mean, for example, that the more different mates that each simian once learned to charm, the more rapidly language, and with it civilization, advanced? _TWELVE_ A doctor, who was making a study of monkeys, once told me that he was trying experiments that bore on the polygamy question. He had a young monkey named Jack who had mated with a female named Jill; and in another cage another newly-wedded pair, Arabella and Archer. Each pair seemed absorbed in each other, and devoted and happy. They even hugged each other at mealtime and exchanged bits of food. After a time their transports grew less fiery, and their affections less fixed. Archer got a bit bored. He was decent about it, though, and when Arabella cuddled beside him he would more or less perfunctorily embrace her. But when he forgot, she grew cross. The same thing occurred a little later in the Jack and Jill cage, only there it was Jill who became a little tired of Jack. Soon each pair was quarreling. They usually made up, pretty soon, and started loving again. But it petered out; each time more quickly. [Illustration: Archer felt bored] Meanwhile the two families had become interested in watching each other. When Jill had repulsed Jack, and he had moped about it awhile, he would begin staring at Arabella, over opposite, and trying to attract her attention. This got Jack in trouble all around. Arabella indignantly made faces at him and then turned her back; and as for Jill, she grew furious, and tore out his fur. But in the next stage, they even stopped hating each other. Each pair grew indifferent. Then the doctor put Jack in with Arabella, and Archer with Jill. Arabella promptly yielded to Jack. New devotion. More transports. Jill and Archer were shocked. Jill clung to the bars of her cage, quivering, and screaming remonstrance; and even blasé Archer chattered angrily at some of the scenes. Then the doctor hung curtains between the cages to shut out the view. Jill and Archer, left to each other, grew interested. They soon were inseparable. The four monkeys, thus re-distributed, were now happy once more, and full of new liveliness and spirit. But before very long, each pair quarreled--and made up--and quarreled--and then grew indifferent, and had cynical thoughts about life. At this point, the doctor put them back with their original mates. And--they met with a rush! Gave cries of recognition and joy, like faithful souls reunited. And when they were tired, they affectionately curled up together; and hugged each other even at mealtime, and exchanged bits of food. * * * * * This was as far as the doctor had gotten, at the time that I met him; and as I have lost touch with him since, I don't know how things were afterward. His theory at the time was, that variety was good for fidelity. "So many of us feel this way, it may be in the blood," he concluded. "Some creatures, such as wolves, are more serious; or perhaps more cold-blooded. Never mate but once. Well--we're not wolves. We can't make wolves our models. Of course we are not monkeys either, but at any rate they are our cousins. Perhaps wolves can be continent without any trouble at all, but it's harder for simians: it may affect their nervous systems injuriously. If we want to know how to behave, according to the way Nature made us, I say that with all due allowances we should study the monkeys." To be sure, these particular monkeys were living in idleness. This corresponds to living in high social circles with us, where men do not have to work, and lack some of the common incentives to home-building. The experiment was not conclusive. Still, even in low social circles-- _THIRTEEN_ Are we or are we not simians? It is no use for any man to try to think anything else out until he has decided first of all where he stands on that question. It is not only in love affairs: let us lay all that aside for the moment. It is in ethics, economics, art, education, philosophy, what-not. If we are fallen angels, we should go this road: if we are super-apes, that. "Our problem is not to discover what we ought to do if we were different, but what we ought to do, being what we are. There is no end to the beings we can imagine different from ourselves; but they do not exist," and we cannot be sure they would be better than we if they did. For, when we imagine them, we must imagine their entire environment; they would have to be a part of some whole that does not now exist. And that new whole, that new reality, being merely a figment of our little minds, "would probably be inferior to the reality that is. For there is this to be said in favor of reality: that we have nothing to compare it with. Our fantasies are always incomplete, because they are fantasies. And reality is complete. We cannot compare their incompleteness with its completeness."[4] [4] From an anonymous article entitled "Tolstoy and Russia" in the _London Times_, Sept. 26, 1918. Too many moralists begin with a dislike of reality: a dislike of men as they are. They are free to dislike them--but not at the same time to be moralists. Their feeling leads them to ignore the obligation which should rest on all teachers, "to discover the best that man can do, not to set impossibilities before him and tell him that if he does not perform them he is damned." Man is moldable; very; and it is desirable that he should aspire. But he is apt to be hasty about accepting any and all general ideals without figuring out whether they are suitable for simian use. One result of his habit of swallowing whole most of the ideals that occur to him, is that he has swallowed a number that strongly conflict. Any ideal whatever strains our digestions if it is hard to assimilate: but when two at once act on us in different ways, it is unbearable. In such a case, the poets will prefer the ideal that's idealest: the hard-headed instinctively choose the one adapted to simians. Whenever this is argued, extremists spring up on each side. One extremist will say that being mere simians we cannot transcend much, and will seem to think that having limitations we should preserve them forever. The other will declare that we are not merely simians, never were just plain animals; or, if we were, souls were somehow smuggled in to us, since which time we have been different. We have all been perfect at heart since that date, equipped with beautiful spirits, which only a strange perverse obstinacy leads us to soil. What this obstinacy is, is the problem that confronts theologians. They won't think of it as simian-ness; they call it original sin. They regard it as the voice of some devil, and say good men should not listen to it. The scientists say it isn't a devil, it is part of our nature, which should of course be civilized and guided, but should not be stamped out. (It might mutilate us dangerously to become under-simianized. Look at Mrs. Humphry Ward and George Washington. Worthy souls, but no flavor.) * * * * * In every field of thought then, two schools appear, that are divided on this: Must we forever be at heart high-grade simians? Or are we at heart something else? For example, in education, we have in the main two great systems. One depends upon discipline. The other on exciting the interest. The teacher who does not recognize or allow for our simian nature, keeps little children at work for long periods at dull and dry tasks. Without some such discipline, he fears that his boys will lack strength. The other system believes they will learn more when their interest is roused; and when their minds, which are mobile by nature, are allowed to keep moving. Or in politics: the best government for simians seems to be based on a parliament: a talk-room, where endless vague thoughts can be expressed. This is the natural child of those primeval sessions that gave pleasure to apes. It is neither an ideal nor a rational arrangement of course. Small executive committees would be better. But not if we are simians. Or in industry: Why do factory workers produce more in eight hours a day than in ten? It is absurd. Super-sheep could not do it. But that is the way men are made. To preach to such beings about the dignity of labor is futile. The dignity of labor is not a simian conception at all. True simians hate to have to work steadily: they call it grind and confinement. They are always ready to pity the toilers who are condemned to this fate, and to congratulate those who escape it, or who can do something else. When they see some performer in spangles risk his life, at a circus, swinging around on trapezes, high up in the air, and when they are told he must do it daily, do they pity _him_? No! Super-elephants would say, and quite properly, "What a horrible life!" But it naturally seems stimulating to simians. Boys envy the fellow. On the other hand whenever we are told about factory life, we instinctively shudder to think of enduring such evils. We see some old workman, filling cans with a whirring machine; and we hear the humanitarians telling us, indignant and grieving, that he actually must stand in that nice, warm, dry room every day, safe from storms and wild beasts, and with nothing to do but fill cans; and at once we groan: "How deadly! What monotonous toil! Shorten his hours!" His work would seem blissful to super-spiders,--but to us it's intolerable. The factory system is meant for other species than ours. Our monkey-blood is also apparent in our judgments of crime. If a crime is committed on impulse, we partly forgive it. Why? Because, being simians, with a weakness for yielding to impulses, we like to excuse ourselves by feeling not accountable for them. Elephants would have probably taken an opposite stand. They aren't creatures of impulse, and would be shocked at crimes due to such causes; their fault is the opposite one of pondering too long over injuries, and becoming vindictive in the end, out of all due proportion. If a young super-elephant were to murder another on impulse, they would consider him a dangerous character and string him right up. But if he could prove that he had long thought of doing it, they would tend to forgive him. "Poor fellow, he brooded," they would say. "That's upsetting to any one." As to modesty and decency, if we are simians we have done well, considering: but if we are something else--fallen angels--we have indeed fallen far. Not being modest by instinct we invent artificial ideals, which are doubtless well-meaning but are inherently of course second-rate, so that even at our best we smell prudish. And as for our worst, when we as we say let ourselves go, we dirty the life-force unspeakably, with chuckles and leers. But a race so indecent by nature as the simians are would naturally have a hard time behaving as though they were not: and the strain of pretending that their thoughts were all pretty and sweet, would naturally send them to smutty extremes for relief. The standards of purity we have adopted are far too strict--for simians. _FOURTEEN_ We were speaking a while ago of the fertility with which simians breed. This is partly due to the constant love interest they take in each other, but it is also reënforced by their reliance on numbers. That reliance will be deep, since, to their numbers, they will owe much success. It will be thus that they will drive out other species, and garrison the globe. Such a race would naturally come to esteem fertility. It will seem profane not to. As time goes on, however, the advantage of numbers will end; and in their higher stages, large numbers will be a great drawback. The resources of a planet are limited, at each stage of the arts. Also, there is only a limited space on a planet. Yet it will come hard to them to think of ever checking their increase. They will bring more young into existence than they can either keep well or feed. The earth will be covered with them everywhere, as far as eye can see. North and south, east and west, there will always be simians huddling. Their cities will be far more distressing than cities of vermin,--for vermin are healthy and calm and successful in life. Ah, those masses of people--unintelligent, superstitious, uncivilized! What a dismal drain they will be on the race's strength! Not merely will they lessen its ultimate chance of achievement; their hardships will always distress and preoccupy minds,--fine, generous minds,--that might have done great things if free: that might have done something constructive at least, for their era, instead of being burned out attacking mere anodyne-problems. Nature will do what it can to lessen the strain, providing an appropriate remedy for their bad behavior in plagues. Many epochs will pass before the simians will learn or dare to control them--for they won't think they can, any more than they dare control propagation. They will reverently call their propagation and plagues "acts of God." When they get tired of reverence and stop their plagues, it will be too soon. Their inventiveness will be--as usual--ahead of their wisdom; and they will unfortunately end the good effects of plagues (as a check) before they are advanced enough to keep down their numbers themselves. Meanwhile, when, owing to the pressure of other desires, any group of primates does happen to become less prolific, they will feel ashamed, talk of race suicide, and call themselves decadent. And they will often be right: for though some regulation of the birth-rate is an obvious good, and its diminution often desirable in any planet's history, yet among simians it will be apt to come from second-rate motives. Greed, selfishness or fear-thoughts will be the incentives, the bribes. Contrivances, rather than continence, will be the method. How audacious, and how disconcerting to Nature, to baffle her thus! Even into her shrine they must thrust their bold paws to control her. Another race viewing them in the garlanded chambers of love, unpacking their singular devices, might think them grotesque: but the busy little simians will be blind to such quaint incongruities. Still, there is a great gift that their excess of passion will bestow on this race: it will give them romance. It will teach them what little they ever will learn about love. Other animals have little romance: there is none in the rut: that seasonal madness that drives them to mate with perhaps the first comer. But the simians will attain to a fine discrimination in love, and this will be their path to the only spiritual heights they can reach. For, in love, their inmost selves will draw near, in the silence of truth; learning little by little what the deepest sincerity means, and what clean hearts and minds and what crystal-clear sight it demands. Such intercommunication of spirit with spirit is at the beginning of all true understanding. It is the beginning of silent cosmic wisdom: it may lead to knowing the ways of that power called God. _FIFTEEN_ Not content with the whole of a planet and themselves too, to study, this race's children will also study the heavens. How few kinds of creatures would ever have felt that impulse, and yet how natural it will seem to these! How boundless and magnificent is the curiosity of these tiny beings, who sit and peer out at the night from their small whirling globe, considering deeply the huge cold seas of space, and learning with wonderful skill to measure the stars. In studies so vast, however, they are tested to the core. In these great journeys the traveler must pay dear for his flaws. For it always is when you most finely are exerting your strength that every weakness you have most tells against you. One weakness of the primates is the character of their self-consciousness. This useful faculty, that can probe so deep, has one naïve defect--it relies too readily on its own findings. It doesn't suspect enough its own unconfessed predilections. It assumes that it can be completely impartial--but isn't. To instance an obvious way in which it will betray them: beings that are intensely self-conscious and aware of their selves, will also instinctively feel that their universe is. What active principle animates the world, they will ask. A great blind force? It is possible. But they will recoil from admitting any such possibility. A self-aware purposeful force then? That is better! (More simian.) "A blind force can't have been the creator of all. It's unthinkable." Any theory _their_ brains find "unthinkable" cannot be true. (This is not to argue that it really is a blind force--or the opposite. It is merely an instance of how little impartial they are.) * * * * * A second typical weakness of this race will come from their fears. They are not either self-sufficing or gallant enough to travel great roads without cringing,--clear-eyed, unafraid. They are finely made, but not nobly made,--in that sense. They will therefore have a too urgent need of religion. Few primates have the courage to face--alone--the still inner mysteries: Infinity, Space and Time. They will think it too terrible, they will feel it would turn them to water, to live through unearthly moments of vision without creeds or beliefs. So they'll get beliefs first. Ah, poor creatures! The cart before the horse! Ah, the blasphemy (pitiful!) of their seeking high spiritual temples, with god-maps or bibles about them, made below in advance! Think of their entering into the presence of Truth, declaring so loudly and boldly they know her already, yet far from willing to stand or fall by her flames--to rise like a phoenix or die as an honorable cinder!--but creeping in, clad in their queer blindfolded beliefs, designed to shield them from her stern, bright tests! Think of Truth sadly--or merrily--eyeing such worms! _SIXTEEN_ Imagine you are watching the Bandarlog at play in the forest. As you behold them and comprehend their natures, now hugely brave and boastful, now full of dread, the most weakly emotional of any intelligent species, ever trying to attract the notice of some greater animal, not happy indeed unless noticed,--is it not plain they are bound to invent things called gods? Don't think for the moment of whether there are gods or not; think of how sure these beings would be to invent them. (Not wait to find them.) Having small self-reliance they can not bear to face life alone. With no self-sufficingness, they must have the countenance of others. It is these pressing needs that will hurry the primates to build, out of each shred of truth they can possibly twist to their purpose, and out of imaginings that will impress them because they are vast, deity after deity to prop up their souls. What a strange company they will be, these gods, in their day, each of them an old bearded simian up in the sky, who begins by fishing the universe out of a void, like a conjurer taking a rabbit out of a hat. (A hat which, if it resembled a void, wasn't there.) And after creating enormous suns and spheres, and filling the farthest heavens with vaster stars, one god will turn back and long for the smell of roast flesh, another will call desert tribes to "holy" wars, and a third will grieve about divorce or dancing. All gods that any groups of simians ever conceive of, from the woodenest little idol in the forest to the mightiest Spirit, no matter how much they may differ, will have one trait in common: a readiness to drop any cosmic affair at short notice, focus their minds on the far-away pellet called Earth, and become immediately wholly concerned, aye, engrossed, with any individual worshipper's woes or desires,--a readiness to notice a fellow when he is going to bed. This will bring indescribable comfort to simian hearts; and a god that neglects this duty won't last very long, no matter how competent he may be in other respects. But one must reciprocate. For the maker of the Cosmos, as they see him, wants noticing too; he is fond of the deference and attention that simians pay him, and naturally he will be angry if it is withheld;--or if he is not, it will be most magnanimous of him. Hence prayers and hymns. Hence queer vague attempts at communing with this noble kinsman. To desire communion with gods is a lofty desire, but hard to attain through an ignobly definite creed. Dealing with the highest, most wordless states of being, the simians will attempt to conceive them in material form. They will have beliefs, for example, as to the furnishings and occupations in heaven. And why? Why, to help men to have religious conceptions without themselves being seers,--which in any true sense of "religious" is an impossible plan. * * * * * In their efforts to be concrete they will make their creeds amusingly simian. Consider the simian amorousness of Jupiter, and the brawls on Olympus. Again, in the old Jewish Bible, what tempts the first pair? The Tree of Knowledge, of course. It appealed to the curiosity of their nature, and who could control _that_! And Satan in the Bible is distinctly a simian's devil. The snake, it is known, is the animal monkeys most dread. Hence when men give their devil a definite form they make him a snake. A race of super-chickens would have pictured their devil a hawk. _SEVENTEEN_ What are the handicaps this race will have in building religions? The greatest is this: they have such small psychic powers. The over-activity of their minds will choke the birth of such powers, or dull them. The race will be less in touch with Nature, some day, than its dogs. It will substitute the compass for its once innate sense of direction. It will lose its gifts of natural intuition, premonition, and rest, by encouraging its use of the mind to be cheaply incessant. This lack of psychic power will cheat them of insight and poise; for minds that are wandering and active, not receptive and still, can seldom or never be hushed to a warm inner peace. One service these restless minds however will do: they eventually will see through the religions they themselves invented. But ages will be thrown away in repeating this process. A simian creed will not be very hard thus to pierce. When forming a religion, they will be in far too much haste, to wait to apply a strict test to their holy men's visions. Furthermore they will have so few visions, that any will awe them; so naturally they will accept any vision as valid. Then their rapid and fertile inventiveness will come into play, and spin the wildest creeds from each vision living dust ever dreamed. They will next expect everybody to believe whatever a few men have seen, on the slippery ground that if you simply try believing it, you will then feel it's true. Such religions are vicarious; their prophets alone will see God, and the rest will be supposed to be introduced to him by the prophets. These "believers" will have no white insight at all of their own. Now, a second-hand believer who is warmed at one remove--if at all--by the breath of the spirit, will want to have exact definitions in the beliefs he accepts. Not having had a vision to go by, he needs plain commandments. He will always try to crystallize creeds. And that, plainly, is fatal. For as time goes on, new and remoter aspects of truth are discovered, which can seldom or never be fitted into creeds that are changeless. * * * * * Over and over again, this will be the process: A spiritual personality will be born; see new truth; and be killed. His new truth not only will not fit into too rigid creeds, but whatever false finality is in them it must contradict. So, the seer will be killed. His truth being mighty, however, it will kill the creeds too. There will then be nothing left to believe in--except the dead seer. For a few generations he may then be understandingly honored. But his priests will feel that is not enough: he must be honored uncritically: so uncritically that, whatever his message, it must be deemed the Whole Truth. Some of his message they themselves will have garbled; and it was not, at best, final; but still it will be made into a fixed creed and given his name. Truth will be given his name. All men who thereafter seek truth must find only his kind, else they won't be his "followers." (To be his co-seekers won't do.) Priests will always hate any new seers who seek further for truth. Their feeling will be that their seer found it, and thus ended all that. Just believe what he says. The job's over. No more truth need be sought. It's a comforting thing to believe cosmic search nicely settled. Thus the mold will be hardened. So new truths, when they come, can but break it. Then men will feel distraught and disillusioned, and civilizations will fall. Thus each cycle will run. So long as men intertwine falsehoods with every seer's visions, both perish, and every civilization that is built on them must perish too. _EIGHTEEN_ If men can ever learn to accept all their truths as not final, and if they can ever learn to build on something better than dogma, they may not be found saying, discouragedly, every once in so often, that every civilization carries in it the seeds of decay. It will carry such seeds with great certainty, though, when they're put there, by the very race, too, that will later deplore the results. Why shouldn't creeds totter when they are jerry-built creeds? On stars where creeds come late in the life of a race; where they spring from the riper, not cruder, reactions of spirit; where they grow out of nobly developed psychic powers that have put their possessors in tune with cosmic music; and where no cheap hallucinations discredit their truths; they perhaps run a finer, more beautiful course than the simians', and open the eyes of the soul to far loftier visions. _NINETEEN_ It has always been a serious matter for men when a civilization decayed. But it may at some future day prove far more serious still. Our hold on the planet is not absolute. Our descendants may lose it. Germs may do them out of it. A chestnut fungus springs up, defies us, and kills all our chestnuts. The boll weevil very nearly baffles us. The fly seems unconquerable. Only a strong civilization, when such foes are about, can preserve us. And our present efforts to cope with such beings are fumbling and slow. We haven't the habit of candidly facing this danger. We read our biological history but we don't take it in. We blandly assume we were always "intended" to rule, and that no other outcome could even be considered by Nature. This is one of the remnants of ignorance certain religions have left: but it's odd that men who don't believe in Easter should still believe this. For the facts are of course this is a hard and precarious world, where every mistake and infirmity must be paid for in full. * * * * * If mankind ever is swept aside as a failure however, what a brilliant and enterprising failure he at least will have been. I felt this with a kind of warm suddenness only today, as I finished these dreamings and drove through the gates of the park. I had been shutting my modern surroundings out of my thoughts, so completely, and living as it were in the wild world of ages ago, that when I let myself come back suddenly to the twentieth century, and stare at the park and the people, the change was tremendous. All around me were the well-dressed descendants of primitive animals, whizzing about in bright motors, past tall, soaring buildings. What gifted, energetic achievers they suddenly seemed! I thought of a photograph I had once seen, of a ship being torpedoed. There it was, the huge, finely made structure, awash in the sea, with tiny black spots hanging on to its side--crew and passengers. The great ship, even while sinking, was so mighty, and those atoms so helpless. Yet, it was those tiny beings that had created that ship. They had planned it and built it and guided its bulk through the waves. They had also invented a torpedo that could rend it asunder. * * * * * It is possible that our race may be an accident, in a meaningless universe, living its brief life uncared-for, on this dark, cooling star: but even so--and all the more--what marvelous creatures we are! What fairy story, what tale from the Arabian Nights of the jinns, is a hundredth part as wonderful as this true fairy story of simians! It is so much more heartening, too, than the tales we invent. A universe capable of giving birth to many such accidents is--blind or not--a good world to live in, a promising universe. And if there are no other such accidents, if we stand alone, if all the uncountable armies of planets are empty, or peopled by animals only, with no keys to thought, then we have done something so mighty, what may it not lead to! What powers may we not develop before the Sun dies! We once thought we lived on God's footstool: it may be a throne. This is no world for pessimists. An amoeba on the beach, blind and helpless, a mere bit of pulp,--that amoeba has grandsons today who read Kant and play symphonies. Will those grandsons in turn have descendants who will sail through the void, discover the foci of forces, the means to control them, and learn how to marshal the planets and grapple with space? Would it after all be any more startling than our rise from the slime? No sensible amoeba would have ever believed for a minute that any of his most remote children would build and run dynamos. Few sensible men of today stop to feel, in their hearts, that we live in the very same world where that miracle happened. This world, and our racial adventure, are magical still. _TWENTY_ Yet although for high-spirited marchers the march is sufficient, there still is that other way of looking at it that we dare not forget. Our adventure may satisfy _us_: does it satisfy Nature? She is letting us camp for awhile here among the wrecked graveyards of mightier dynasties, not one of which met her tests. Their bones are the message the epochs she murdered have left us: we have learned to decipher their sickening warning at last. * * * * * Yes, and even if we are permitted to have a long reign, and are not laid away with the failures, are we a success? We need so much spiritual insight, and we have so little. Our airships may some day float over the hills of Arcturus, but how will that help us if we cannot find the soul of the world? Is that soul alive and loving? or cruel? or callous? or dead? We have no sure vision. Hopes, guesses, beliefs--that is all. There are sounds we are deaf to, there are strange sights invisible to us. There are whole realms of splendor, it may be, of which we are heedless; and which we are as blind to as ants to the call of the sea. Life is enormously flexible--look at all that we've done to our dogs,--but we carry our hairy past with us wherever we go. The wise St. Bernards and the selfish toy lap-dogs are brothers, and some things are possible for them and others are not. So with us. There are definite limits to simian civilizations, due in part to some primitive traits that help keep us alive, and in part to the mere fact that every being has to be something, and when one is a simian one is not also everything else. Our main-springs are fixed, and our principal traits are deep-rooted. We cannot now re-live the ages whose imprint we bear. We have but to look back on our past to have hope in our future: but--it will be only _our_ future, not some other race's. We shall win our own triumphs, yet know that they would have been different, had we cared above all for creativeness, beauty, or love. * * * * * So we run about, busy and active, marooned on this star, always violently struggling, yet with no clearly seen goal before us. Men, animals, insects--what tribe of us asks any object, except to keep trying to satisfy its own master appetite? If the ants were earth's lords they would make no more use of their lordship than to learn and enjoy every possible method of toiling. Cats would spend their span of life, say, trying new kinds of guile. And we, who crave so much to know, crave so little but knowing. Some of us wish to know Nature most; those are the scientists. Others, the saints and philosophers, wish to know God. Both are alike in their hearts, yes, in spite of their quarrels. Both seek to assuage, to no end, the old simian thirst. If we wanted to _be_ Gods--but ah, can we grasp that ambition? A NOTE ON THE TYPE IN WHICH THIS BOOK IS SET _The text of this book was set on the linotype in Baskerville. The punches for this face were cut under the supervision of George W. Jones, an eminent English printer. Linotype Baskerville is a facsimile cutting from type cast from the original matrices of a face designed by John Baskerville. The original face was the forerunner of the "modern" group of type faces. ¶ John Baskerville (1706-75), of Birmingham, England, a writing-master, with a special renown for cutting inscriptions in stone, began experimenting about 1750 with punch-cutting and making typographical material. It was not until 1757 that he published his first work, a Virgil in royal quarto, with great-primer letters. This was followed by his famous editions of Milton, the Bible, the Book of Common Prayer, and several Latin classic authors. His types, at first criticized as unnecessarily slender, delicate, and feminine, in time were recognized as both distinct and elegant, and both his types and his printing were greatly admired. Printers, however, preferred the stronger types of Caslon, and Baskerville before his death repented of having attempted the business of printing. For four years after his death his widow continued to conduct his business. She then sold all his punches and matrices to the Société Littéraire-typographique, which used some of the types for the sumptuous Kehl edition of Voltaire's works in seventy volumes.--_ COMPOSED, PRINTED AND BOUND BY H. WOLFF, NEW YORK. PAPER MADE BY P. F. GLATFELTER & CO., SPRING GROVE, PA. 
2921	----	THE PRESENT CONDITION OF ORGANIC NATURE Lecture I. (of VI.), "Lectures To Working Men", at the Museum of Practical Geology, 1863, On Darwin's work: "Origin of Species". By Thomas H. Huxley EDITOR'S NOTE Of the great thinkers of the nineteenth century, Thomas Henry Huxley, son of an Ealing schoolmaster, was undoubtedly the most noteworthy. His researches in biology, his contributions to scientific controversy, his pungent criticisms of conventional beliefs and thoughts have probably had greater influence than the work of any other English scientist. And yet he was a "self-made" intellectualist. In spite of the fact that his father was a schoolmaster he passed through no regular course of education. "I had," he said, "two years of a pandemonium of a school (between eight and ten) and after that neither help nor sympathy in any intellectual direction till I reached manhood." When he was twelve a craving for reading found satisfaction in Hutton's "Geology," and when fifteen in Hamilton's "Logic." At seventeen Huxley entered as a student at Charing Cross Hospital, and three years later he was M.B. and the possessor of the gold medal for anatomy and physiology. An appointment as surgeon in the navy proved to be the entry to Huxley's great scientific career, for he was gazetted to the "Rattlesnake", commissioned for surveying work in Torres Straits. He was attracted by the teeming surface life of tropical seas and his study of it was the commencement of that revolution in scientific knowledge ultimately brought about by his researches. Thomas Henry Huxley was born at Ealing on May 4, 1825, and died at Eastbourne June 29, 1895. LECTURES AND ESSAYS BY T.H. HUXLEY ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE NOTICE TO THE FIRST EDITION. The Publisher of these interesting Lectures, having made an arrangement for their publication with Mr. J. A. Mays, the Reporter, begs to append the following note from Professor Huxley:-- "Mr. J. Aldous Mays, who is taking shorthand notes of my 'Lectures to Working Men,' has asked me to allow him, on his own account, to print those Notes for the use of my audience. I willingly accede to this request, on the understanding that a notice is prefixed to the effect that I have no leisure to revise the Lectures, or to make alterations in them, beyond the correction of any important error in a matter of fact." THE PRESENT CONDITION OF ORGANIC NATURE. When it was my duty to consider what subject I would select for the six lectures [*To Working Men, at the Museum of Practical Geology, 1863.] which I shall now have the pleasure of delivering to you, it occurred to me that I could not do better than endeavour to put before you in a true light, or in what I might perhaps with more modesty call, that which I conceive myself to be the true light, the position of a book which has been more praised and more abused, perhaps, than any book which has appeared for some years;--I mean Mr. Darwin's work on the "Origin of Species". That work, I doubt not, many of you have read; for I know the inquiring spirit which is rife among you. At any rate, all of you will have heard of it,--some by one kind of report and some by another kind of report; the attention of all and the curiosity of all have been probably more or less excited on the subject of that work. All I can do, and all I shall attempt to do, is to put before you that kind of judgment which has been formed by a man, who, of course, is liable to judge erroneously; but, at any rate, of one whose business and profession it is to form judgments upon questions of this nature. And here, as it will always happen when dealing with an extensive subject, the greater part of my course--if, indeed, so small a number of lectures can be properly called a course--must be devoted to preliminary matters, or rather to a statement of those facts and of those principles which the work itself dwells upon, and brings more or less directly before us. I have no right to suppose that all or any of you are naturalists; and even if you were, the misconceptions and misunderstandings prevalent even among naturalists on these matters would make it desirable that I should take the course I now propose to take,--that I should start from the beginning,--that I should endeavour to point out what is the existing state of the organic world,--that I should point out its past condition,--that I should state what is the precise nature of the undertaking which Mr. Darwin has taken in hand; that I should endeavour to show you what are the only methods by which that undertaking can be brought to an issue, and to point out to you how far the author of the work in question has satisfied those conditions, how far he has not satisfied them, how far they are satisfiable by man, and how far they are not satisfiable by man. To-night, in taking up the first part of this question, I shall endeavour to put before you a sort of broad notion of our knowledge of the condition of the living world. There are many ways of doing this. I might deal with it pictorially and graphically. Following the example of Humboldt in his "Aspects of Nature", I might endeavour to point out the infinite variety of organic life in every mode of its existence, with reference to the variations of climate and the like; and such an attempt would be fraught with interest to us all; but considering the subject before us, such a course would not be that best calculated to assist us. In an argument of this kind we must go further and dig deeper into the matter; we must endeavour to look into the foundations of living Nature, if I may so say, and discover the principles involved in some of her most secret operations. I propose, therefore, in the first place, to take some ordinary animal with which you are all familiar, and, by easily comprehensible and obvious examples drawn from it, to show what are the kind of problems which living beings in general lay before us; and I shall then show you that the same problems are laid open to us by all kinds of living beings. But first, let me say in what sense I have used the words "organic nature." In speaking of the causes which lead to our present knowledge of organic nature, I have used it almost as an equivalent of the word "living," and for this reason,--that in almost all living beings you can distinguish several distinct portions set apart to do particular things and work in a particular way. These are termed "organs," and the whole together is called "organic." And as it is universally characteristic of them, this term "organic" has been very conveniently employed to denote the whole of living nature,--the whole of the plant world, and the whole of the animal world. Few animals can be more familiar to you than that whose skeleton is shown on our diagram. You need not bother yourselves with this "Equus caballus" written under it; that is only the Latin name of it, and does not make it any better. It simply means the common Horse. Suppose we wish to understand all about the Horse. Our first object must be to study the structure of the animal. The whole of his body is inclosed within a hide, a skin covered with hair; and if that hide or skin be taken off, we find a great mass of flesh, or what is technically called muscle, being the substance which by its power of contraction enables the animal to move. These muscles move the hard parts one upon the other, and so give that strength and power of motion which renders the Horse so useful to us in the performance of those services in which we employ him. And then, on separating and removing the whole of this skin and flesh, you have a great series of bones, hard structures, bound together with ligaments, and forming the skeleton which is represented here. [Illustration: FIGURE 1. (Section through a horse.)] [Illustration: FIGURE 2. (Section through a cell.)] In that skeleton there are a number of parts to be recognized. The long series of bones, beginning from the skull and ending in the tail, is called the spine, and those in front are the ribs; and then there are two pairs of limbs, one before and one behind; and there are what we all know as the fore-legs and the hind-legs. If we pursue our researches into the interior of this animal, we find within the framework of the skeleton a great cavity, or rather, I should say, two great cavities,--one cavity beginning in the skull and running through the neck-bones, along the spine, and ending in the tail, containing the brain and the spinal marrow, which are extremely important organs. The second great cavity, commencing with the mouth, contains the gullet, the stomach, the long intestine, and all the rest of those internal apparatus which are essential for digestion; and then in the same great cavity, there are lodged the heart and all the great vessels going from it; and, besides that, the organs of respiration--the lungs: and then the kidneys, and the organs of reproduction, and so on. Let us now endeavour to reduce this notion of a horse that we now have, to some such kind of simple expression as can be at once, and without difficulty, retained in the mind, apart from all minor details. If I make a transverse section, that is, if I were to saw a dead horse across, I should find that, if I left out the details, and supposing I took my section through the anterior region, and through the fore-limbs, I should have here this kind of section of the body (Fig. 1). Here would be the upper part of the animal--that great mass of bones that we spoke of as the spine (a, Fig. 1). Here I should have the alimentary canal (b, Fig. 1). Here I should have the heart (c, Fig. 1); and then you see, there would be a kind of double tube, the whole being inclosed within the hide; the spinal marrow would be placed in the upper tube (a, Fig. 1), and in the lower tube (d d, Fig. 1), there would be the alimentary canal (b), and the heart (c); and here I shall have the legs proceeding from each side. For simplicity's sake, I represent them merely as stumps (e e, Fig. 1). Now that is a horse--as mathematicians would say--reduced to its most simple expression. Carry that in your minds, if you please, as a simplified idea of the structure of the Horse. The considerations which I have now put before you belong to what we technically call the 'Anatomy' of the Horse. Now, suppose we go to work upon these several parts,--flesh and hair, and skin and bone, and lay open these various organs with our scalpels, and examine them by means of our magnifying-glasses, and see what we can make of them. We shall find that the flesh is made up of bundles of strong fibres. The brain and nerves, too, we shall find, are made up of fibres, and these queer-looking things that are called ganglionic corpuscles. If we take a slice of the bone and examine it, we shall find that it is very like this diagram of a section of the bone of an ostrich, though differing, of course, in some details; and if we take any part whatsoever of the tissue, and examine it, we shall find it all has a minute structure, visible only under the microscope. All these parts constitute microscopic anatomy or 'Histology.' These parts are constantly being changed; every part is constantly growing, decaying, and being replaced during the life of the animal. The tissue is constantly replaced by new material; and if you go back to the young state of the tissue in the case of muscle, or in the case of skin, or any of the organs I have mentioned, you will find that they all come under the same condition. Every one of these microscopic filaments and fibres (I now speak merely of the general character of the whole process)--every one of these parts--could be traced down to some modification of a tissue which can be readily divided into little particles of fleshy matter, of that substance which is composed of the chemical elements, carbon, hydrogen, oxygen, and nitrogen, having such a shape as this (Fig. 2). These particles, into which all primitive tissues break up, are called cells. If I were to make a section of a piece of the skin of my hand, I should find that it was made up of these cells. If I examine the fibres which form the various organs of all living animals, I should find that all of them, at one time or other, had been formed out of a substance consisting of similar elements; so that you see, just as we reduced the whole body in the gross to that sort of simple expression given in Fig. 1, so we may reduce the whole of the microscopic structural elements to a form of even greater simplicity; just as the plan of the whole body may be so represented in a sense (Fig. 1), so the primary structure of every tissue may be represented by a mass of cells (Fig. 2). Having thus, in this sort of general way, sketched to you what I may call, perhaps, the architecture of the body of the Horse (what we term technically its Morphology), I must now turn to another aspect. A horse is not a mere dead structure: it is an active, living, working machine. Hitherto we have, as it were, been looking at a steam-engine with the fires out, and nothing in the boiler; but the body of the living animal is a beautifully-formed active machine, and every part has its different work to do in the working of that machine, which is what we call its life. The Horse, if you see him after his day's work is done, is cropping the grass in the fields, as it may be, or munching the oats in his stable. What is he doing? His jaws are working as a mill--and a very complex mill too--grinding the corn, or crushing the grass to a pulp. As soon as that operation has taken place, the food is passed down to the stomach, and there it is mixed with the chemical fluid called the gastric juice, a substance which has the peculiar property of making soluble and dissolving out the nutritious matter in the grass, and leaving behind those parts which are not nutritious; so that you have, first, the mill, then a sort of chemical digester; and then the food, thus partially dissolved, is carried back by the muscular contractions of the intestines into the hinder parts of the body, while the soluble portions are taken up into the blood. The blood is contained in a vast system of pipes, spreading through the whole body, connected with a force pump,--the heart,--which, by its position and by the contractions of its valves, keeps the blood constantly circulating in one direction, never allowing it to rest; and then, by means of this circulation of the blood, laden as it is with the products of digestion, the skin, the flesh, the hair, and every other part of the body, draws from it that which it wants, and every one of these organs derives those materials which are necessary to enable it to do its work. The action of each of these organs, the performance of each of these various duties, involve in their operation a continual absorption of the matters necessary for their support, from the blood, and a constant formation of waste products, which are returned to the blood, and conveyed by it to the lungs and the kidneys, which are organs that have allotted to them the office of extracting, separating, and getting rid of these waste products; and thus the general nourishment, labour, and repair of the whole machine is kept up with order and regularity. But not only is it a machine which feeds and appropriates to its own support the nourishment necessary to its existence--it is an engine for locomotive purposes. The Horse desires to go from one place to another; and to enable it to do this, it has those strong contractile bundles of muscles attached to the bones of its limbs, which are put in motion by means of a sort of telegraphic apparatus formed by the brain and the great spinal cord running through the spine or backbone; and to this spinal cord are attached a number of fibres termed nerves, which proceed to all parts of the structure. By means of these the eyes, nose, tongue, and skin--all the organs of perception--transmit impressions or sensations to the brain, which acts as a sort of great central telegraph-office, receiving impressions and sending messages to all parts of the body, and putting in motion the muscles necessary to accomplish any movement that may be desired. So that you have here an extremely complex and beautifully-proportioned machine, with all its parts working harmoniously together towards one common object--the preservation of the life of the animal. Now, note this: the Horse makes up its waste by feeding, and its food is grass or oats, or perhaps other vegetable products; therefore, in the long run, the source of all this complex machinery lies in the vegetable kingdom. But where does the grass, or the oat, or any other plant, obtain this nourishing food-producing material? At first it is a little seed, which soon begins to draw into itself from the earth and the surrounding air matters which in themselves contain no vital properties whatever; it absorbs into its own substance water, an inorganic body; it draws into its substance carbonic acid, an inorganic matter; and ammonia, another inorganic matter, found in the air; and then, by some wonderful chemical process, the details of which chemists do not yet understand, though they are near foreshadowing them, it combines them into one substance, which is known to us as 'Protein,' a complex compound of carbon, hydrogen, oxygen, and nitrogen, which alone possesses the property of manifesting vitality and of permanently supporting animal life. So that, you see, the waste products of the animal economy, the effete materials which are continually being thrown off by all living beings, in the form of organic matters, are constantly replaced by supplies of the necessary repairing and rebuilding materials drawn from the plants, which in their turn manufacture them, so to speak, by a mysterious combination of those same inorganic materials. Let us trace out the history of the Horse in another direction. After a certain time, as the result of sickness or disease, the effect of accident, or the consequence of old age, sooner or later, the animal dies. The multitudinous operations of this beautiful mechanism flag in their performance, the Horse loses its vigour, and after passing through the curious series of changes comprised in its formation and preservation, it finally decays, and ends its life by going back into that inorganic world from which all but an inappreciable fraction of its substance was derived. Its bones become mere carbonate and phosphate of lime; the matter of its flesh, and of its other parts, becomes, in the long run, converted into carbonic acid, into water, and into ammonia. You will now, perhaps, understand the curious relation of the animal with the plant, of the organic with the inorganic world, which is shown in this diagram (Fig. 3). [Illustration: FIGURE 3. (Diagram showing material relationship of the Vegetable, Animal and Inorganic Worlds.)] The plant gathers these inorganic materials together and makes them up into its own substance. The animal eats the plant and appropriates the nutritious portions to its own sustenance, rejects and gets rid of the useless matters; and, finally, the animal itself dies, and its whole body is decomposed and returned into the inorganic world. There is thus a constant circulation from one to the other, a continual formation of organic life from inorganic matters, and as constant a return of the matter of living bodies to the inorganic world; so that the materials of which our bodies are composed are largely, in all probability, the substances which constituted the matter of long extinct creations, but which have in the interval constituted a part of the inorganic world. Thus we come to the conclusion, strange at first sight, that the MATTER constituting the living world is identical with that which forms the inorganic world. And not less true is it that, remarkable as are the powers or, in other words, as are the FORCES which are exerted by living beings, yet all these forces are either identical with those which exist in the inorganic world, or they are convertible into them; I mean in just the same sense as the researches of physical philosophers have shown that heat is convertible into electricity, that electricity is convertible into magnetism, magnetism into mechanical force or chemical force, and any one of them with the other, each being measurable in terms of the other,--even so, I say, that great law is applicable to the living world. Consider why is the skeleton of this horse capable of supporting the masses of flesh and the various organs forming the living body, unless it is because of the action of the same forces of cohesion which combines together the particles of matter composing this piece of chalk? What is there in the muscular contractile power of the animal but the force which is expressible, and which is in a certain sense convertible, into the force of gravity which it overcomes? Or, if you go to more hidden processes, in what does the process of digestion differ from those processes which are carried on in the laboratory of the chemist? Even if we take the most recondite and most complex operations of animal life--those of the nervous system, these of late years have been shown to be--I do not say identical in any sense with the electrical processes--but this has been shown, that they are in some way or other associated with them; that is to say, that every amount of nervous action is accompanied by a certain amount of electrical disturbance in the particles of the nerves in which that nervous action is carried on. In this way the nervous action is related to electricity in the same way that heat is related to electricity; and the same sort of argument which demonstrates the two latter to be related to one another shows that the nervous forces are correlated to electricity; for the experiments of M. Dubois Reymond and others have shown that whenever a nerve is in a state of excitement, sending a message to the muscles or conveying an impression to the brain, there is a disturbance of the electrical condition of that nerve which does not exist at other times; and there are a number of other facts and phenomena of that sort; so that we come to the broad conclusion that not only as to living matter itself, but as to the forces that matter exerts, there is a close relationship between the organic and the inorganic world--the difference between them arising from the diverse combination and disposition of identical forces, and not from any primary diversity, so far as we can see. I said just now that the Horse eventually died and became converted into the same inorganic substances from whence all but an inappreciable fraction of its substance demonstrably originated, so that the actual wanderings of matter are as remarkable as the transmigrations of the soul fabled by Indian tradition. But before death has occurred, in the one sex or the other, and in fact in both, certain products or parts of the organism have been set free, certain parts of the organisms of the two sexes have come into contact with one another, and from that conjunction, from that union which then takes place, there results the formation of a new being. At stated times the mare, from a particular part of the interior of her body, called the ovary, gets rid of a minute particle of matter comparable in all essential respects with that which we called a cell a little while since, which cell contains a kind of nucleus in its centre, surrounded by a clear space and by a viscid mass of protein substance (Fig. 2); and though it is different in appearance from the eggs which we are mostly acquainted with, it is really an egg. After a time this minute particle of matter, which may only be a small fraction of a grain in weight, undergoes a series of changes,--wonderful, complex changes. Finally, upon its surface there is fashioned a little elevation, which afterwards becomes divided and marked by a groove. The lateral boundaries of the groove extend upwards and downwards, and at length give rise to a double tube. In the upper smaller tube the spinal marrow and brain are fashioned; in the lower, the alimentary canal and heart; and at length two pairs of buds shoot out at the sides of the body, which are the rudiments of the limbs. In fact a true drawing of a section of the embryo in this state would in all essential respects resemble that diagram of a horse reduced to its simplest expression, which I first placed before you (Fig. 1). Slowly and gradually these changes take place. The whole of the body, at first, can be broken up into "cells," which become in one place metamorphosed into muscle,--in another place into gristle and bone,--in another place into fibrous tissue,--and in another into hair; every part becoming gradually and slowly fashioned, as if there were an artificer at work in each of these complex structures that we have mentioned. This embryo, as it is called, then passes into other conditions. I should tell you that there is a time when the embryos of neither dog, nor horse, nor porpoise, nor monkey, nor man, can be distinguished by any essential feature one from the other; there is a time when they each and all of them resemble this one of the Dog. But as development advances, all the parts acquire their speciality, till at length you have the embryo converted into the form of the parent from which it started. So that you see, this living animal, this horse, begins its existence as a minute particle of nitrogenous matter, which, being supplied with nutriment (derived, as I have shown, from the inorganic world), grows up according to the special type and construction of its parents, works and undergoes a constant waste, and that waste is made good by nutriment derived from the inorganic world; the waste given off in this way being directly added to the inorganic world; and eventually the animal itself dies, and, by the process of decomposition, its whole body is returned to those conditions of inorganic matter in which its substance originated. This, then, is that which is true of every living form, from the lowest plant to the highest animal--to man himself. You might define the life of every one in exactly the same terms as those which I have now used; the difference between the highest and the lowest being simply in the complexity of the developmental changes, the variety of the structural forms, the diversity of the physiological functions which are exerted by each. If I were to take an oak tree as a specimen of the plant world, I should find that it originated in an acorn, which, too, commenced in a cell; the acorn is placed in the ground, and it very speedily begins to absorb the inorganic matters I have named, adds enormously to its bulk, and we can see it, year after year, extending itself upward and downward, attracting and appropriating to itself inorganic materials, which it vivifies, and eventually, as it ripens, gives off its own proper acorns, which again run the same course. But I need not multiply examples,--from the highest to the lowest the essential features of life are the same, as I have described in each of these cases. So much, then, for these particular features of the organic world, which you can understand and comprehend, so long as you confine yourself to one sort of living being, and study that only. But, as you know, horses are not the only living creatures in the world; and again, horses, like all other animals, have certain limits--are confined to a certain area on the surface of the earth on which we live,--and, as that is the simpler matter, I may take that first. In its wild state, and before the discovery of America, when the natural state of things was interfered with by the Spaniards, the Horse was only to be found in parts of the earth which are known to geographers as the Old World; that is to say, you might meet with horses in Europe, Asia, or Africa; but there were none in Australia, and there were none whatsoever in the whole continent of America, from Labrador down to Cape Horn. This is an empirical fact, and it is what is called, stated in the way I have given it you, the 'Geographical Distribution' of the Horse. Why horses should be found in Europe, Asia, and Africa, and not in America, is not obvious; the explanation that the conditions of life in America are unfavourable to their existence, and that, therefore, they had not been created there, evidently does not apply; for when the invading Spaniards, or our own yeomen farmers, conveyed horses to these countries for their own use, they were found to thrive well and multiply very rapidly; and many are even now running wild in those countries, and in a perfectly natural condition. Now, suppose we were to do for every animal what we have here done for the Horse,--that is, to mark off and distinguish the particular district or region to which each belonged; and supposing we tabulated all these results, that would be called the Geographical Distribution of animals, while a corresponding study of plants would yield as a result the Geographical Distribution of plants. I pass on from that now, as I merely wished to explain to you what I meant by the use of the term 'Geographical Distribution.' As I said, there is another aspect, and a much more important one, and that is, the relations of the various animals to one another. The Horse is a very well-defined matter-of-fact sort of animal, and we are all pretty familiar with its structure. I dare say it may have struck you, that it resembles very much no other member of the animal kingdom, except perhaps the Zebra or the Ass. But let me ask you to look along these diagrams. Here is the skeleton of the Horse, and here the skeleton of the Dog. You will notice that we have in the Horse a skull, a backbone and ribs, shoulder-blades and haunch-bones. In the fore-limb, one upper arm-bone, two fore arm-bones, wrist-bones (wrongly called knee), and middle hand-bones, ending in the three bones of a finger, the last of which is sheathed in the horny hoof of the fore-foot: in the hind-limb, one thigh-bone, two leg-bones, anklebones, and middle foot-bones, ending in the three bones of a toe, the last of which is encased in the hoof of the hind-foot. Now turn to the Dog's skeleton. We find identically the same bones, but more of them, there being more toes in each foot, and hence more toe-bones. Well, that is a very curious thing! The fact is that the Dog and the Horse--when one gets a look at them without the outward impediments of the skin--are found to be made in very much the same sort of fashion. And if I were to make a transverse section of the Dog, I should find the same organs that I have already shown you as forming parts of the Horse. Well, here is another skeleton--that of a kind of Lemur--you see he has just the same bones; and if I were to make a transverse section of it, it would be just the same again. In your mind's eye turn him round, so as to put his backbone in a position inclined obliquely upwards and forwards, just as in the next three diagrams, which represent the skeletons of an Orang, a Chimpanzee, a Gorilla, and you find you have no trouble in identifying the bones throughout; and lastly turn to the end of the series, the diagram representing a man's skeleton, and still you find no great structural feature essentially altered. There are the same bones in the same relations. From the Horse we pass on and on, with gradual steps, until we arrive at last at the highest known forms. On the other hand, take the other line of diagrams, and pass from the Horse downwards in the scale to this fish; and still, though the modifications are vastly greater, the essential framework of the organization remains unchanged. Here, for instance, is a Porpoise: here is its strong backbone, with the cavity running through it, which contains the spinal cord; here are the ribs, here the shoulder blade; here is the little short upper-arm bone, here are the two forearm bones, the wrist-bone, and the finger-bones. Strange, is it not, that the Porpoise should have in this queer-looking affair--its flapper (as it is called), the same fundamental elements as the fore-leg of the Horse or the Dog, or the Ape or Man; and here you will notice a very curious thing,--the hinder limbs are absent. Now, let us make another jump. Let us go to the Codfish: here you see is the forearm, in this large pectoral fin--carrying your mind's eye onward from the flapper of the Porpoise. And here you have the hinder limbs restored in the shape of these ventral fins. If I were to make a transverse section of this, I should find just the same organs that we have before noticed. So that, you see, there comes out this strange conclusion as the result of our investigations, that the Horse, when examined and compared with other animals, is found by no means to stand alone in nature; but that there are an enormous number of other creatures which have backbones, ribs, and legs, and other parts arranged in the same general manner, and in all their formation exhibiting the same broad peculiarities. I am sure that you cannot have followed me even in this extremely elementary exposition of the structural relations of animals, without seeing what I have been driving at all through, which is, to show you that, step by step, naturalists have come to the idea of a unity of plan, or conformity of construction, among animals which appeared at first sight to be extremely dissimilar. And here you have evidence of such a unity of plan among all the animals which have backbones, and which we technically call "Vertebrata". But there are multitudes of other animals, such as crabs, lobsters, spiders, and so on, which we term "Annulosa". In these I could not point out to you the parts that correspond with those of the Horse,--the backbone, for instance,--as they are constructed upon a very different principle, which is also common to all of them; that is to say, the Lobster, the Spider, and the Centipede, have a common plan running through their whole arrangement, in just the same way that the Horse, the Dog, and the Porpoise assimilate to each other. Yet other creatures--whelks, cuttlefishes, oysters, snails, and all their tribe ("Mollusca")--resemble one another in the same way, but differ from both "Vertebrata" and "Annulosa"; and the like is true of the animals called "Coelenterata" (Polypes) and "Protozoa" (animalcules and sponges). Now, by pursuing this sort of comparison, naturalists have arrived at the conviction that there are,--some think five, and some seven,--but certainly not more than the latter number--and perhaps it is simpler to assume five--distinct plans or constructions in the whole of the animal world; and that the hundreds of thousands of species of creatures on the surface of the earth, are all reducible to those five, or, at most, seven, plans of organization. But can we go no further than that? When one has got so far, one is tempted to go on a step and inquire whether we cannot go back yet further and bring down the whole to modifications of one primordial unit. The anatomist cannot do this; but if he call to his aid the study of development, he can do it. For we shall find that, distinct as those plans are, whether it be a porpoise or man, or lobster, or any of those other kinds I have mentioned, every one begins its existence with one and the same primitive form,--that of the egg, consisting, as we have seen, of a nitrogenous substance, having a small particle or nucleus in the centre of it. Furthermore, the earlier changes of each are substantially the same. And it is in this that lies that true "unity of organization" of the animal kingdom which has been guessed at and fancied for many years; but which it has been left to the present time to be demonstrated by the careful study of development. But is it possible to go another step further still, and to show that in the same way the whole of the organic world is reducible to one primitive condition of form? Is there among the plants the same primitive form of organization, and is that identical with that of the animal kingdom? The reply to that question, too, is not uncertain or doubtful. It is now proved that every plant begins its existence under the same form; that is to say, in that of a cell--a particle of nitrogenous matter having substantially the same conditions. So that if you trace back the oak to its first germ, or a man, or a horse, or lobster, or oyster, or any other animal you choose to name, you shall find each and all of these commencing their existence in forms essentially similar to each other: and, furthermore, that the first processes of growth, and many of the subsequent modifications, are essentially the same in principle in almost all. In conclusion, let me, in a few words, recapitulate the positions which I have laid down. And you must understand that I have not been talking mere theory; I have been speaking of matters which are as plainly demonstrable as the commonest propositions of Euclid--of facts that must form the basis of all speculations and beliefs in Biological science. We have gradually traced down all organic forms, or, in other words, we have analyzed the present condition of animated nature, until we found that each species took its origin in a form similar to that under which all the others commence their existence. We have found the whole of the vast array of living forms, with which we are surrounded, constantly growing, increasing, decaying and disappearing; the animal constantly attracting, modifying, and applying to its sustenance the matter of the vegetable kingdom, which derived its support from the absorption and conversion of inorganic matter. And so constant and universal is this absorption, waste, and reproduction, that it may be said with perfect certainty that there is left in no one of our bodies at the present moment a millionth part of the matter of which they were originally formed! We have seen, again, that not only is the living matter derived from the inorganic world, but that the forces of that matter are all of them correlative with and convertible into those of inorganic nature. This, for our present purposes, is the best view of the present condition of organic nature which I can lay before you: it gives you the great outlines of a vast picture, which you must fill up by your own study. In the next lecture I shall endeavour in the same way to go back into the past, and to sketch in the same broad manner the history of life in epochs preceding our own. 
20818	----	ON THE GENESIS OF SPECIES. [Illustration] ON THE GENESIS OF SPECIES. BY ST. GEORGE MIVART, F.R.S. London: MACMILLAN AND CO. 1871. [_The Right of Translation and Reproduction is reserved._] LONDON: R. CLAY, SONS, AND TAYLOR, PRINTERS, BREAD STREET HILL. * * * * * TO SIR HENRY HOLLAND, BART., M.D., F.R.S., D.C.L., ETC. ETC. MY DEAR SIR HENRY, In giving myself the pleasure to dedicate, as I now do, this work to you, it is not my intention to identify you with any views of my own advocated in it. I simply avail myself of an opportunity of paying a tribute of esteem and regard to my earliest scientific friend--the first to encourage me in pursuing the study of nature. I remain, MY DEAR SIR HENRY, Ever faithfully yours, ST. GEORGE MIVART. 7, NORTH BANK, REGENT'S PARK, _December 8, 1870._ {vii} * * * * * CONTENTS. CHAPTER I. _INTRODUCTORY_ The problem of the genesis of species stated.--Nature of its probable solution.--Importance of the question.--Position here defended.--Statement of the DARWINIAN THEORY.--Its applicability to details of geographical distribution; to rudimentary structures; to homology; to mimicry, &c.--Consequent utility of the theory.--Its wide acceptance.--Reasons for this other than, and in addition to, its scientific value. Its simplicity.--Its bearing on religious questions.--_Odium theologicum_ and _odium antitheologicum_.--The antagonism supposed by many to exist between it and theology neither necessary nor universal.--Christian authorities in favour of evolution.--Mr. Darwin's "Animals and Plants under Domestication."--Difficulties of the Darwinian theory enumerated ... _Page_ 1 CHAPTER II. _THE INCOMPETENCY OF "NATURAL SELECTION" TO ACCOUNT FOR THE INCIPIENT STAGES OF USEFUL STRUCTURES._ Mr. Darwin supposes that Natural-Selection acts by slight variations.--These must be useful at once.--Difficulties as to the giraffe; as to mimicry; as to the heads of flat-fishes; as to the origin and constancy of the vertebrate, limbs; as to whalebone; as to the young kangaroo; as to sea-urchins; as to certain processes of {viii} metamorphosis; as to the mammary gland; as to certain ape characters; as to the rattlesnake and cobra; as to the process of formation of the eye and ear; as to the fully developed condition of the eye and ear; as to the voice; as to shell-fish; as to orchids; as to ants.--The necessity for the simultaneous modification of many individuals.--Summary and conclusion ... _Page_ 23 CHAPTER III. _THE CO-EXISTENCE OF CLOSELY SIMILAR STRUCTURES OF DIVERSE ORIGIN._ Chances against concordant variations.--Examples of discordant ones.--Concordant variations not unlikely on a non-Darwinian evolutionary hypothesis.--Placental and implacental mammals.--Birds and reptiles.--Independent origins of similar sense organs.--The ear.--The eye.--Other coincidences.--Causes besides Natural Selection produce concordant variations in certain geographical regions.--Causes besides Natural Selection produce concordant variations in certain zoological and botanical groups.--There are homologous parts not genetically related.--Harmony in respect of the organic and inorganic worlds.--Summary and conclusion ... _Page_ 63 CHAPTER IV. _MINUTE AND GRADUAL MODIFICATIONS._ There are difficulties as to minute modifications, even if not fortuitous.--Examples of sudden and considerable modifications of different kinds.--Professor Owen's view.--Mr. Wallace.--Professor Huxley.--Objections to sudden changes.--Labyrinthodont.--Potto.--Cetacea.--As to origin of bird's wing.--Tendrils of climbing plants.--Animals once supposed to be connecting links.--Early specialization of structure.--Macrauchenia.--Glyptodon.--Sabre-toothed tiger.--Conclusion ... _Page_ 97 {ix} CHAPTER V. _AS TO SPECIFIC STABILITY._ What is meant by the phrase "specific stability;" such stability to be expected _a priori_, or else considerable changes at once.--Rapidly increasing difficulty of intensifying race characters; alleged causes of this phenomenon; probably an internal cause co-operates.--A certain definiteness in variations.--Mr. Darwin admits the principle of specific stability in certain cases of unequal variability.--The goose.--The peacock.--The guinea fowl.--Exceptional causes of variation under domestication.--Alleged tendency to reversion.--Instances.--Sterility of hybrids.--Prepotency of pollen of same species, but of different race.--Mortality in young gallinaceous hybrids.--A bar to intermixture exists somewhere.--Guinea-pigs.--Summary and conclusion ... _Page_ 113 CHAPTER VI. _SPECIES AND TIME._ Two relations of species to time.--No evidence of past existence of minutely intermediate forms when such might be expected _a priori_.--Bats, Pterodactyles, Dinosauria, and Birds.--Ichthyosauria, Chelonia, and Anoura.--Horse ancestry.--Labyrinthodonts and Trilobites.--Two subdivisions of the second relation of species to time.--Sir William Thomson's views.--Probable period required for ultimate specific evolution from primitive ancestral forms.---Geometrical increase of time required for rapidly multiplying increase of structural differences.--Proboscis monkey.--Time required for deposition of strata necessary for Darwinian evolution.--High organization of Silurian forms of life.--Absence of fossils in oldest rocks.--Summary and conclusion ... _Page_ 128 CHAPTER VII. _SPECIES AND SPACE._ The geographical distribution of animals presents difficulties.--These not insurmountable in themselves; harmonize with other difficulties.--Fresh-water fishes.--Forms common to Africa and India; to Africa and South America; to China and Australia; to North America and {x} China; to New Zealand and South America; to South America and Tasmania; to South America and Australia.--Pleurodont lizards.--Insectivorous mammals.--Similarity of European and South American frogs.--Analogy between European salmon and fishes of New Zealand, &c.--An ancient Antarctic continent probable.--Other modes of accounting for facts of distribution.--Independent origin of closely similar forms.--Conclusion ... _Page_ 144 CHAPTER VIII. _HOMOLOGIES._ Animals made up of parts mutually related in various ways.--What homology is.--Its various kinds.--Serial homology.--Lateral homology.--Vertical homology.--Mr. Herbert Spencer's explanations.--An internal power necessary, as shown by facts of comparative anatomy.---Of teratology.--M. St. Hilaire.--Professor Burt Wilder.--Foot-wings.--Facts of pathology.--Mr. James Paget.--Dr. William Budd.--The existence of such an internal power of individual development diminishes the improbability of an analogous law of specific origination ... _Page_ 155 CHAPTER IX. _EVOLUTION AND ETHICS._ The origin of morals an inquiry not foreign to the subject of this book.--Modern utilitarian view as to that origin.--Mr. Darwin's speculation as to the origin of the abhorrence of incest.--Cause assigned by him insufficient.--Care of the aged and infirm opposed by "Natural Selection;" also self-abnegation and asceticism.--Distinctness of the ideas right and useful.--Mr. John Stuart Mill.--Insufficiency of "Natural Selection" to account for the origin of the distinction between duty and profit.--Distinction of moral acts into material and formal.--No ground{xi} for believing that formal morality exists in brutes.--Evidence that it does exist in savages.--Facility with which savages may be misunderstood.--Objections as to diversity of customs.--Mr. Button's review of Mr. Herbert Spencer.--Anticipatory character of morals.--Sir John Lubbock's explanation.--Summary and conclusion ... _Page_ 188 CHAPTER X. _PANGENESIS._ A provisional hypothesis supplementing "Natural Selection."--Statement of the hypothesis.--Difficulty as to multitude of gemmules.--As to certain modes of reproduction.--As to formations without the requisite gemmules.--Mr. Lewes and Professor Delpino.--Difficulty as to developmental force of gemmules.--As to their spontaneous fission.--Pangenesis and Vitalism.--Paradoxical reality.--Pangenesis scarcely superior to anterior hypotheses.--Buffon.--Owen.--Herbert Spencer.--Gemmules as mysterious as "physiological units."--Conclusion ... _Page_ 208 CHAPTER XI. _SPECIFIC GENESIS._ Review of the statements and arguments of preceding chapters.--Cumulative argument against predominant action of "Natural Selection."--Whether anything positive as well as negative can be enunciated.--Constancy of laws of nature does not necessarily imply constancy of specific evolution.--Possible exceptional stability of existing epoch.--Probability that an internal cause of change exists.--Innate powers somewhere must be accepted.--Symbolism of molecular action under vibrating impulses. Professor Owen's statement.--Statement of the Author's view.--It avoids the difficulties which oppose "Natural Selection."--It harmonizes apparently conflicting conceptions.--Summary and conclusion ... _Page_ 220 [Page xii] CHAPTER XII. _THEOLOGY AND EVOLUTION._ Prejudiced opinions on the subject.--"Creation" sometimes denied from prejudice.--The unknowable.--Mr. Herbert Spencer's objections to theism; to creation.--Meanings of term "creation."--Confusion from not distinguishing between "primary" and "derivative" creation.--Mr. Darwin's objections.--Bearing of Christianity on evolution.--Supposed opposition, the result of a misconception.--Theological authority not opposed to evolution.--St. Augustin.--St. Thomas Aquinas.--Certain consequences of want of flexibility of mind.--Reason and imagination.--The first cause and demonstration.--Parallel between Christianity and natural theology.--What evolution of species is.--Professor Agassiz.--Innate powers must be recognized.--Bearing of evolution on religious belief.--Professor Huxley.--Professor Owen.--Mr. Wallace.--Mr. Darwin.--_A priori_ conception of Divine action.--Origin of man.--Absolute creation and dogma.--Mr. Wallace's view.--A supernatural origin for man's body not necessary.--Two orders of being in man.--Two modes of origin.--Harmony of the physical, hyperphysical, and supernatural.--Reconciliation of science and religion as regards evolution.--Conclusion ... _Page_ 243 INDEX ... _Page_ 289 {xiii} LIST OF ILLUSTRATIONS. Leaf Butterfly in flight and repose (_from Mr. A. Wallace's "Malay Archipelago"_) ... 31 Walking-Leaf Insect ... 35 Pleuronectidæ, with the peculiarly placed eye in different positions (_from Dr. Traquair's paper in Linn. Soc. Trans., 1865_) ... 37, 166 Mouth of Whale (_from Professor Owen's "Odontography"_) ... 40 Four plates of Baleen seen obliquely from within (_from Professor Owen's "Odontography"_) ... 41 Dugong ... 41, 175 Echinus or Sea Urchin ... 43, 167 Pedicellariæ of Echinus very much enlarged ... 44 Rattlesnake ... 49 Cobra (_from Sir Andrew Smith's "Southern Africa"_) ... 50 Wingbones of Pterodactyle, Bat, and Bird (_from Mr. Andrew Murray's "Geographical Distribution of Mammals"_) ... 64, 130, 157 Skeleton of Flying-Dragon ... 65, 158 Centipede (_from a specimen in the Museum of the Royal College of Surgeons_) ... 66, 159 Teeth of Urotrichus and Perameles ... 68 The Archeopteryx (_from Professor Owen's "Anatomy of Vertebrata"_) ... 73, 132 {xiv} Cuttle-Fish ... 75, 141 Skeleton of Ichthyosaurus ... 78, 107, 132, 177 Cytheridea Torosa (_from Messrs. Brady and Robertson's paper in Ann. and Mag. of Nat. Hist., 1870_) ... 79 A Polyzoon, with Bird's-head processes ... 80 Bird's-head processes greatly enlarged ... 81 Antechimis Minutissimus and Mus Delicatulus (_from Mr. Andrew Murray's "Geographical Distribution of Mammals"_) ... 82 Outlines of Wings of Butterflies of Celebes compared with those of allied species elsewhere ... 86 Great Shielded Grasshopper ... 89 The Six-shafted Bird of Paradise ... 90 The Long-tailed Bird of Paradise ... 91 The Red Bird of Paradise ... 92 Horned Flies ... 93 The Magnificent Bird of Paradise ... 93 _(The above seven figures are from Mr. A. Wallace's "Malay Archipelago"_) Much enlarged horizontal Section of the Tooth of a Labyrinthodon (_from Professor Owen's "Odontography"_) ... 104 Hand of the Potto (_from life_) ... 105 Skeleton of Plesiosaurus ... 106, 133 The Aye-Aye (_from Trans, of Zool. Soc._) ... 108 Dentition of Sabre-toothed Tiger (_from Professor Owen's "Odontography"_) ... 110 Trilobite ... 135, 171 Inner side of Lower Jaw of Pleurodont Lizard (_from Professor Owen's "Odontography"_) ... 148 Solenodon (_from Berlin Trans._) ... 149 Tarsal Bones of Galago and Cheirogaleus (_from Proc. Zool. Soc._) ... 159 Squilla ... 160 Parts of the Skeleton of the Lobster ... 161 [Page xv] Spine of Galago Allenii (_from Proc. Zool. Soc._) ... 162 Vertebrae of Axolotl (_from Proc. Zool. Soc._) ... 165 Annelid undergoing spontaneous fission ... 169, 211 Aard-Vark (_Orycteropus capensis_) ... 174 Pangolin (_Manis_) ... 175 Skeleton of Manus and Pes of a Tailed Batrachian (_from Professor Gegenbaur's "Tarsus and Carpus"_) ... 178 Flexor Muscles of Hand of Nycticetus (_from Proc. Zool. Soc._) ... 180 The Fibres of Corti ... 279 {1} * * * * * THE GENESIS OF SPECIES. CHAPTER I. _INTRODUCTORY._ The problem of the genesis of species stated.--Nature of its probable solution.--Importance of the question.--Position here defended.--Statement of the DARWINIAN THEORY.--Its applicability to details of geographical distribution; to rudimentary structures; to homology; to mimicry, &c.--Consequent utility of the theory.--Its wide acceptance.--Reasons for this, other than, and in addition to, its scientific value.--Its simplicity.--Its bearing on religious questions.--_Odium theologicum_ and _odium antitheologicum_.--The antagonism supposed by many to exist between it and theology neither necessary nor universal.--Christian authorities in favour of evolution.--Mr. Darwin's "Animals and Plants under Domestication."--Difficulties of the Darwinian theory enumerated. The great problem which has so long exercised the minds of naturalists, namely, that concerning the origin of different kinds of animals and plants, seems at last to be fairly on the road to receive--perhaps at no very distant future--as satisfactory a solution as it can well have. But the problem presents peculiar difficulties. The birth of a "species" has often been compared with that of an "individual." The origin, however, of even an individual animal or plant (that which determines an embryo to evolve itself,--as, _e.g._, a spider rather than a beetle, a rose-plant {2} rather than a pear) is shrouded in obscurity. _A fortiori_ must this be the case with the origin of a "species." Moreover, the analogy between a "species" and an "individual" is a very incomplete one. The word "individual" denotes a concrete whole with a real, separate, and distinct existence. The word "species," on the other hand, denotes a peculiar congeries of characters, innate powers and qualities, and a certain nature realized indeed in individuals, but having no separate existence, except ideally as a thought in some mind. Thus the birth of a "species" can only be compared metaphorically, and very imperfectly, with that of an "individual." Individuals as _individuals_, actually and directly produce and bring forth other individuals; but no "congeries of characters" no "common nature" _as such_, can directly bring forth another "common nature," because, _per se_, it has no existence (other than ideal) apart from the individuals in which it is manifested. The problem then is, "by what combination of natural laws does a new 'common nature' appear upon the scene of realized existence?" _i.e._ how is an individual embodying such new characters produced? For the approximation we have of late made towards the solution of this problem, we are mainly indebted to the invaluable labours and active brains of Charles Darwin and Alfred Wallace. Nevertheless, important as has been the impulse and direction given by those writers to both our observations and speculations, the solution will not (if the views here advocated are correct) ultimately present that aspect and character with which it has issued from the hands of those writers. Neither, most certainly, will that solution agree in appearance or substance with the more or less crude conceptions which have been put forth by most of the opponents of Messrs. Darwin and Wallace. [Page 3] Rather, judging from the more recent manifestations of thought on opposite sides, we may expect the development of some _tertium quid_--the resultant of forces coming from different quarters, and not coinciding in direction with any one of them. As error is almost always partial truth, and so consists in the exaggeration or distortion of one verity by the suppression of another which qualifies and modifies the former, we may hope, by the synthesis of the truths contended for by various advocates, to arrive at the one conciliating reality. Signs of this conciliation are not wanting: opposite scientific views, opposite philosophical conceptions, and opposite religious beliefs, are rapidly tending by their vigorous conflict to evolve such a systematic and comprehensive view of the genesis of species as will completely harmonize with the teachings of science, philosophy, and religion. To endeavour to add one stone to this temple of concord, to try and remove a few of the misconceptions and mutual misunderstandings which oppose harmonious action, is the aim and endeavour of the present work. This aim it is hoped to attain, not by shirking difficulties, but analysing them, and by endeavouring to dig down to the common root which supports and unites diverging stems of truth. It cannot but be a gain when the labourers in the three fields above mentioned, namely, science, philosophy, and religion, shall fully recognize this harmony. Then the energy too often spent in futile controversy, or withheld through prejudice, may be profitably and reciprocally exercised for the mutual benefit of all. Remarkable is the rapidity with which an interest in the question of specific origination has spread. But a few years ago it scarcely occupied the minds of any but naturalists. Then the crude theory put forth by Lamarck, and by his English interpreter the author of the "Vestiges of Creation," had rather discredited than helped on a belief in organic evolution--a belief, that is, in new kinds being produced from older {4} ones by the ordinary and constant operation of natural laws. Now, however, this belief is widely diffused. Indeed, there are few drawing-rooms where it is not the subject of occasional discussion, and artisans and schoolboys have their views as to the permanence of organic forms. Moreover, the reception of this doctrine tends actually, though by no means necessarily, to be accompanied by certain beliefs with regard to quite distinct and very momentous subject-matter. So that the question of the "Genesis of Species" is not only one of great interest, but also of much importance. But though the calm and thorough consideration of this matter is at the present moment exceedingly desirable, yet the actual importance of the question itself as to its consequences in the domain of theology has been strangely exaggerated by many, both of its opponents and supporters. This is especially the case with that form of the evolution theory which is associated with the name of Mr. Darwin; and yet neither the refutation nor the demonstration of that doctrine would be necessarily accompanied by the results which are hoped for by one party and dreaded by another. The general theory of evolution has indeed for some time past steadily gained ground, and it may be safely predicted that the number of facts which can be brought forward in its support will, in a few years, be vastly augmented. But the prevalence of this theory need alarm no one, for it is, without any doubt, perfectly consistent with strictest and most orthodox Christian theology. Moreover, it is not altogether without obscurities, and cannot yet be considered as fully demonstrated. The special Darwinian hypothesis, however, is beset with certain scientific difficulties, which must by no means be ignored, and some of which, I venture to think, are absolutely insuperable. What Darwinism or "Natural Selection" is, will be shortly explained; but before doing so, I think {5} it well to state the object of this book, and the view taken up and defended in it. It is its object to maintain the position that "Natural Selection" acts, and indeed must act, but that still, in order that we may be able to account for the production of known kinds of animals and plants, it requires to be supplemented by the action of some other natural law or laws as yet undiscovered.[1] Also, that the consequences which have been drawn from Evolution, whether exclusively Darwinian or not, to the prejudice of religion, by no means follow from it, and are in fact illegitimate. The Darwinian theory of "Natural Selection" may be shortly stated thus:[2]-- Every kind of animal and plant tends to increase in numbers in a geometrical progression. Every kind of animal and plant transmits a general likeness, with individual differences, to its offspring. Every individual may present minute variations of any kind and in any direction. Past time has been practically infinite. Every individual has to endure a very severe struggle for existence, owing to the tendency to geometrical increase of all kinds of animals and plants, while the total animal and vegetable population (man and his agency excepted) remains almost stationary. Thus, every variation of a kind tending to save the life of the individual possessing it, or to enable it more surely to propagate its kind, will in the long run be preserved, and will transmit its favourable peculiarity to some of its offspring, which peculiarity will thus become intensified {6} till it reaches the maximum degree of utility. On the other hand, individuals presenting unfavourable peculiarities will be ruthlessly destroyed. The action of this law of Natural Selection may thus be well represented by the convenient expression "survival of the fittest."[3] Now this conception of Mr. Darwin's is perhaps the most interesting theory, in relation to natural science, which has been promulgated during the present century. Remarkable, indeed, is the way in which it groups together such a vast and varied series of biological[4] facts, and even paradoxes, which it appears more or less clearly to explain, as the following instances will show. By this theory of "Natural Selection," light is thrown on the more singular facts relating to the geographical distribution of animals and plants; for example, on the resemblance between the past and present inhabitants of different parts of the earth's surface. Thus in Australia remains have been found of creatures closely allied to kangaroos and other kinds of pouched beasts, which in the present day exist nowhere but in the Australian region. Similarly in South America, and nowhere else, are found sloths and armadillos, and in that same part of the world have been discovered bones of animals different indeed from existing sloths and armadillos, but yet much more nearly related to them than to any other kinds whatever. Such coincidences between the existing and antecedent geographical distribution of forms are numerous. Again, "Natural Selection" serves to explain the circumstance that often in adjacent islands we find animals closely resembling, and appearing to represent, each other; while if certain of these islands show signs (by depth of surrounding sea or what not) of more ancient separation, the animals inhabiting them exhibit a {7} corresponding divergence.[5] The explanation consists in representing the forms inhabiting the islands as being the modified descendants of a common stock, the modification being greatest where the separation has been the most prolonged. "Rudimentary structures" also receive an explanation by means of this theory. These structures are parts which are apparently functionless and useless where they occur, but which represent similar parts of large size and functional importance in other animals. Examples of such "rudimentary structures" are the foetal teeth of whales, and of the front part of the jaw of ruminating quadrupeds. These foetal structures are minute in size, and never cut the gum, but are reabsorbed without ever coming into use, while no other teeth succeed them or represent them in the adult condition of those animals. The mammary glands of all male beasts constitute another example, as also does the wing of the apteryx--a New Zealand bird utterly incapable of flight, and with the wing in a quite rudimentary condition (whence the name of the animal). Yet this rudimentary wing contains bones which are miniature representatives of the ordinary wing-bones of birds of flight. Now, the presence of these useless bones and teeth is explained if they may be considered as actually being the inherited diminished representatives of parts of large size and functional importance in the remote ancestors of these various animals. Again, the singular facts of "homology" are capable of a similar explanation. "Homology" is the name applied to the investigation of those profound resemblances which have so often been found to underlie superficial differences between animals of very different form and habit. Thus man, the horse, the whale, and the bat, all have the pectoral limb, whether it be the arm, or fore-leg, or paddle, or wing, formed on essentially the same type, though the number and proportion of parts may{8} more or less differ. Again, the butterfly and the shrimp, different as they are in appearance and mode of life, are yet constructed on the same common plan, of which they constitute diverging manifestations. No _a priori_ reason is conceivable why such similarities should be necessary, but they are readily explicable on the assumption of a genetic relationship and affinity between the animals in question, assuming, that is, that they are the modified descendants of some ancient form--their common ancestor. That remarkable series of changes which animals undergo before they attain their adult condition, which is called their process of development, and during which they more or less closely resemble other animals during the early stages of the same process, has also great light thrown on it from the same source. The question as to the singularly complex resemblances borne by every adult animal and plant to a certain number of other animals and plants--resemblances by means of which the adopted zoological and botanical systems of classification have been possible--finds its solution in a similar manner, classification becoming the expression of a genealogical relationship. Finally, by this theory--and as yet by this alone--can any explanation be given of that extraordinary phenomenon which is metaphorically termed _mimicry_. Mimicry is a close and striking, yet superficial resemblance borne by some animal or plant to some other, perhaps very different, animal or plant. The "walking leaf" (an insect belonging to the grasshopper and cricket order) is a well-known and conspicuous instance of the assumption by an animal of the appearance of a vegetable structure (see illustration on p. 35); and the bee, fly, and spider orchids are familiar examples of a converse resemblance. Birds, butterflies, reptiles, and even fish, seem to bear in certain instances a similarly striking resemblance to other birds, butterflies, reptiles, and fish, of altogether distinct kinds. The explanation of this matter which "Natural Selection" offers, as to animals, is that certain varieties of {9} one kind have found exemption from persecution in consequence of an accidental resemblance which such varieties have exhibited to animals of another kind, or to plants; and that they were thus preserved, and the degree of resemblance was continually augmented in their descendants. As to plants, the explanation offered by this theory might perhaps be that varieties of plants which presented a certain superficial resemblance in their flowers to insects, have thereby been helped to propagate their kind, the visit of certain insects being useful or indispensable to the fertilization of many flowers. We have thus a whole series of important facts which "Natural Selection" helps us to understand and co-ordinate. And not only are all these diverse facts strung together, as it were, by the theory in question; not only does it explain the development of the complex instincts of the beaver, the cuckoo, the bee, and the ant, as also the dazzling brilliancy of the humming-bird, the glowing tail and neck of the peacock, and the melody of the nightingale; the perfume of the rose and the violet, the brilliancy of the tulip and the sweetness of the nectar of flowers; not only does it help us to understand all these, but serves as a basis of future research and of inference from the known to the unknown, and it guides the investigator to the discovery of new facts which, when ascertained, it seems also able to co-ordinate.[6] Nay, "Natural Selection" seems capable of application not only to the building up of the smallest and most insignificant organisms, but even of extension beyond the biological domain altogether, so as possibly to have relation to the stable equilibrium of the solar system{10} itself, and even of the whole sidereal universe. Thus, whether this theory be true or false, all lovers of natural science should acknowledge a deep debt of gratitude to Messrs. Darwin and Wallace, on account of its practical utility. But the utility of a theory by no means implies its truth. What do we not owe, for example, to the labours of the Alchemists? The emission theory of light, again, has been pregnant with valuable results, as still is the Atomic theory, and others which will readily suggest themselves. With regard to Mr. Darwin (with whose name, on account of the noble self-abnegation of Mr. Wallace, the theory is in general exclusively associated), his friends may heartily congratulate him on the fact that he is one of the few exceptions to the rule respecting the non-appreciation of a prophet in his own country. It would be difficult to name another living labourer in the field of physical science who has excited an interest so widespread, and given rise to so much praise, gathering round him, as he has done, a chorus of more or less completely acquiescing disciples, themselves masters in science, and each the representative of a crowd of enthusiastic followers. Such is the Darwinian theory of "Natural Selection," such are the more remarkable facts which it is potent to explain, and such is the reception it has met with in the world. A few words now as to the reasons for the very widespread interest it has awakened, and the keenness with which the theory has been both advocated and combated. The important bearing it has on such an extensive range of scientific facts, its utility, and the vast knowledge and great ingenuity of its promulgator, are enough to account for the heartiness of its reception by those learned in natural history. But quite other causes have concurred to produce the general and higher degree of interest felt in the theory beside the readiness with which it harmonizes with biological facts. These latter could only be appreciated by physiologists, zoologists, and botanists; whereas the Darwinian theory, so novel and so startling, has found a {11} cloud of advocates and opponents beyond and outside the world of physical science. In the first place, it was inevitable that a great crowd of half-educated men and shallow thinkers should accept with eagerness the theory of "Natural Selection," or rather what they think to be such (for few things are more remarkable than the way in which it has been misunderstood), on account of a certain characteristic it has in common with other theories; which should not be mentioned in the same breath with it, except, as now, with the accompaniment of protest and apology. We refer to its remarkable simplicity, and the ready way in which phenomena the most complex appear explicable by a cause for the comprehension of which laborious and persevering efforts are not required, but which may be represented by the simple phrase "survival of the fittest." With nothing more than this, can, on the Darwinian theory, all the most intricate facts of distribution and affinity, form, and colour, be accounted for; as well the most complex instincts and the most admirable adjustments, such as those of the human eye and ear. It is in great measure then, owing to this supposed simplicity, and to a belief in its being yet easier and more simple than it is, that Darwinism, however imperfectly understood, has become a subject for general conversation, and has been able thus widely to increase a certain knowledge of biological matters; and this excitation of interest in quarters where otherwise it would have been entirely wanting, is an additional motive for gratitude on the part of naturalists to the authors of the new theory. At the same time it must be admitted that a similar "simplicity"--the apparently easy explanation of complex phenomena--also constitutes the charm of such matters as hydropathy and phrenology, in the eyes of the unlearned or half-educated public. It is indeed _the_ charm of all those seeming "short cuts" to knowledge, by which the labour of mastering scientific details is spared to those who yet believe that {12} without such labour they can attain all the most valuable results of scientific research. It is not, of course, for a moment meant to imply that its "simplicity" tells at all against "Natural Selection," but only that the actual or supposed possession of that quality is a strong reason for the wide and somewhat hasty acceptance of the theory, whether it be true or not. In the second place, it was inevitable that a theory appearing to have very grave relations with questions of the last importance and interest to man, that is, with questions of religious belief, should call up an army of assailants and defenders. Nor have the supporters of the theory much reason, in many cases, to blame the more or less unskilful and hasty attacks of adversaries, seeing that those attacks have been in great part due to the unskilful and perverse advocacy of the cause on the part of some of its adherents. If the _odium theologicum_ has inspired some of its opponents, it is undeniable that the _odium antitheologicum_ has possessed not a few of its supporters. It is true (and in appreciating some of Mr. Darwin's expressions it should never be forgotten) that the theory has been both at its first promulgation and since vehemently attacked and denounced as unchristian, nay, as necessarily atheistic; but it is not less true that it has been made use of as a weapon of offence by irreligious writers, and has been again and again, especially in continental Europe, thrown, as it were, in the face of believers, with sneers and contumely. When we recollect the warmth with which what he thought was Darwinism was advocated by such a writer as Professor Vogt, one cause of his zeal was not far to seek--a zeal, by the way, certainly not "according to knowledge;" for few conceptions could have been more conflicting with true Darwinism than the theory he formerly maintained, but has since abandoned, viz. that the men of the Old World were descended from African and Asiatic apes, while, similarly, the American apes were the progenitors of the human beings of the New World. The cause of this palpable error in a too eager disciple{13} one might hope was not anxiety to snatch up all or any arms available against Christianity, were it not for the tone unhappily adopted by this author. But it is unfortunately quite impossible to mistake his meaning and intention, for he is a writer whose offensiveness is gross, while it is sometimes almost surpassed by an amazing shallowness. Of course, as might fully be expected, he adopts and reproduces the absurdly trivial objections to absolute morality drawn from differences in national customs.[7] And he seems to have as little conception of the distinction between "formally" moral actions and those which are only "materially" moral, as of that between the _verbum mentale_ and the _verbum oris_. As an example of his onesidedness, it may be remarked that he compares the skulls of the American monkeys (_Cebus apella_ and _C. albifrons_) with the intention of showing that man is of several distinct species, because skulls of different men are less alike than are those of these two monkeys; and he does this regardless of how the skulls of domestic animals (with which it is far more legitimate to compare races of men than with wild kinds), _e.g._ of different dogs or pigeons, tell precisely in the opposite direction. Regardless also of the fact that perhaps no genus of monkeys is in a more unsatisfactory state as to the determination of its different kinds than the genus chosen by him for illustration. This is so much the case that J. A. Wagner (in his supplement to Schreber's great work on Beasts) at first included all the kinds in a single species. As to the strength of his prejudice and his regretable coarseness, one quotation will be enough to display both. Speaking of certain early Christian missionaries, he says,[8] "It is not so very improbable that the new religion, before which the flourishing Roman civilization relapsed into a state of barbarism, should have been introduced by people in whose {14} skulls the anatomist finds simious characters so well developed, and in which the phrenologist finds the organ of veneration so much enlarged. I shall, in the meanwhile, call these simious narrow skulls of Switzerland 'Apostle skulls,' as I imagine that in life they must have resembled the type of Peter, the Apostle, as represented in Byzantine-Nazarene art." In face of such a spirit, can it be wondered at that disputants have grown warm? Moreover, in estimating the vehemence of the opposition which has been offered, it should be borne in mind that the views defended by religious writers are, or should be, all-important in their eyes. They could not be expected to view with equanimity the destruction in many minds of "theology, natural and revealed, psychology, and metaphysics;" nor to weigh with calm and frigid impartiality arguments which seemed to them to be fraught with results of the highest moment to mankind, and, therefore, imposing on their consciences strenuous opposition as a first duty. Cool judicial impartiality in them would have been a sign perhaps of intellectual gifts, but also of a more important deficiency of generous emotion. It is easy to complain of the onesidedness of many of those who oppose Darwinism in the interest of orthodoxy; but not at all less patent is the intolerance and narrow-mindedness of some of those who advocate it, avowedly or covertly, in the interest of heterodoxy. This hastiness of rejection or acceptance, determined by ulterior consequences believed to attach to "Natural Selection," is unfortunately in part to be accounted for by some expressions and a certain tone to be found in Mr. Darwin's writings. That his expressions, however, are not always to be construed literally is manifest. His frequent use metaphorically of the expressions, "contrivance," for example, and "purpose," has elicited, from the Duke of Argyll and others, criticisms which fail to tell against their {15} opponent, because such expressions are, in Mr. Darwin's writings, merely figurative--metaphors, and nothing more. It may be hoped, then, that a similar looseness of expression will account for passages of a directly opposite tendency to that of his theistic metaphors. Moreover, it must not be forgotten that he frequently uses that absolutely theological term, "the Creator," and that he has retained in all the editions of his "Origin of Species" an expression which has been much criticised. He speaks "of life, with its several powers, having been originally breathed by the Creator into a few forms, or into one."[9] This is merely mentioned in justice to Mr. Darwin, and by no means because it is a position which this book is intended to support. For, from Mr. Darwin's usual mode of speaking, it appears that by such divine action he means a supernatural intervention, whereas it is here contended that throughout the whole process of physical evolution--the first manifestation of life included--_supernatural_ action is assuredly not to be looked for. Again, in justice to Mr. Darwin, it may be observed that he is addressing the general public, and opposing the ordinary and common objections of popular religionists, who have inveighed against "Evolution" and "Natural Selection" as atheistic, impious, and directly conflicting with the dogma of creation. Still, in so important a matter, it is to be regretted that he did not take the trouble to distinguish between such merely popular views and those which repose upon some more venerable authority. Mr. John Stuart Mill has replied to similar critics, and shown that the assertion that his philosophy is irreconcilable with theism is unfounded; and it would have been better if Mr. Darwin had dealt in the same manner with some of his assailants, and shown the futility of certain of their objections when {16} viewed from a more elevated religious standpoint. Instead of so doing, he seems to adopt the narrowest notions of his opponents, and, far from endeavouring to expand them, appears to wish to endorse them, and to lend to them the weight of his authority. It is thus that Mr. Darwin seems to admit and assume that the idea of "creation" necessitates a belief in an interference with, or dispensation of, natural laws, and that "creation" must be accompanied by arbitrary and unorderly phenomena. None but the crudest conceptions are placed by him to the credit of supporters of the dogma of creation, and it is constantly asserted that they, to be consistent, must offer "creative fiats" as explanations of physical phenomena, and be guilty of numerous other such absurdities. It is impossible, therefore, to acquit Mr. Darwin of at least a certain carelessness in this matter; and the result is, he has the appearance of opposing ideas which he gives no clear evidence of having ever fully appreciated. He is far from being alone in this, and perhaps merely takes up and reiterates, without much consideration, assertions previously assumed by others. Nothing could be further from Mr. Darwin's mind than any, however small, intentional misrepresentation; and it is therefore the more unfortunate that he should not have shown any appreciation of a position opposed to his own other than that gross and crude one which he combats so superfluously--that he should appear, even for a moment, to be one of those, of whom there are far too many, who first misrepresent their adversary's view, and then elaborately refute it; who, in fact, erect a doll utterly incapable of self-defence and then, with a flourish of trumpets and many vigorous strokes, overthrow the helpless dummy they had previously raised. This is what many do who more or less distinctly oppose theism in the interests, as they believe, of physical science; and they often represent, amongst other things, a gross and narrow anthropomorphism as the necessary consequence of views opposed to those which they themselves advocate. {17} Mr. Darwin and others may perhaps be excused if they have not devoted much time to the study of Christian philosophy; but they have no right to assume or accept, without careful examination, as an unquestioned fact, that in that philosophy there is a necessary antagonism between the two ideas, "creation" and "evolution," as applied to organic forms. It is notorious and patent to all who choose to seek, that many distinguished Christian thinkers have accepted and do accept both ideas, _i.e._ both "creation" and "evolution." As much as ten years ago, an eminently Christian writer observed: "The creationist theory does not necessitate the perpetual search after manifestations of miraculous powers and perpetual 'catastrophes.' Creation is not a miraculous interference with the laws of nature, but the very institution of those laws. Law and regularity, not arbitrary intervention, was the patristic ideal of creation. With this notion, they admitted without difficulty the most surprising origin of living creatures, provided it took place by _law_. They held that when God said, 'Let the waters produce,' 'Let the earth produce,' He conferred forces on the elements of earth and water, which enabled them naturally to produce the various species of organic beings. This power, they thought, remains attached to the elements throughout all time."[10] The same writer quotes St. Augustine and St. Thomas Aquinas, to the effect that, "in the institution of nature we do not look for miracles, but for the laws of nature."[11] And, again, St. Basil,[12] speaks of the continued operation of natural laws in the production of all organisms. [Page 18] So much for writers of early and mediæval times. As to the present day, the Author can confidently affirm that there are many as well versed in theology as Mr. Darwin is in his own department of natural knowledge, who would not be disturbed by the thorough demonstration of his theory. Nay, they would not even be in the least painfully affected at witnessing the generation of animals of complex organization by the skilful artificial arrangement of natural forces, and the production, in the future, of a fish, by means analogous to those by which we now produce urea. And this because they know that the possibility of such phenomena, though by no means actually foreseen, has yet been fully provided for in the old philosophy centuries before Darwin, or even before Bacon, and that their place in the system can be at once assigned them without even disturbing its order or marring its harmony. Moreover, the old tradition in this respect has never been abandoned, however much it may have been ignored or neglected by some modern writers. In proof of this it may be observed that perhaps no post-mediæval theologian has a wider reception amongst Christians throughout the world than Suarez, who has a separate section[13] in opposition to those who maintain the distinct creation of the various kinds--or substantial forms--of organic life. But the consideration of this matter must be deferred for the present, and the question of evolution, whether Darwinian or other, be first gone into. It is proposed, after that has been done, to return to this subject (here merely alluded to), and to consider at some length the bearing of "Evolution," whether Darwinian or non-Darwinian, upon "Creation and Theism." Now we will revert simply to the consideration of the theory of "Natural Selection" itself. {19} Whatever may have hitherto been the amount of acceptance that this theory has met with, all, I think, anticipated that the appearance of Mr. Darwin's large and careful work on "Animals and Plants under Domestication" could but further increase that acceptance. It is, however, somewhat problematical how far such anticipations will be realized. The newer book seems to add after all but little in support of the theory, and to leave most, if not all, its difficulties exactly where they were. It is a question, also, whether the hypothesis of "Pangenesis"[14] may not be found rather to encumber than to support the theory it was intended to subserve. However, the work in question treats only of domestic animals, and probably the next instalment will address itself more vigorously and directly to the difficulties which seem to us yet to bar the way to a complete acceptance of the doctrine. If the theory of Natural Selection can be shown to be quite insufficient to explain any considerable number of important phenomena connected with the origin of species, that theory, as _the_ explanation, must be considered as provisionally discredited. If other causes than Natural (including sexual) Selection can be proved to have acted--if variation can in any cases be proved to be subject to certain determinations in special directions by other means than Natural Selection, it then becomes probable _a priori_ that it is so in others, and that Natural Selection depends upon, and only supplements, such means, {20} which conception is opposed to the pure Darwinian position. Now it is certain, _a priori_, that variation is obedient to some law and therefore that "Natural Selection" itself must be capable of being subsumed into some higher law; and it is evident, I believe, _a posteriori_, that Natural Selection is, at the very least, aided and supplemented by some other agency. Admitting, then, organic and other evolution, and that new forms of animals and plants (new species, genera, &c.) have from time to time been evolved from preceding animals and plants, it follows, if the views here advocated are true, that this evolution has not taken place by the action of "Natural Selection" _alone_, but through it (amongst other influences) aided by the concurrent action of some other natural law or laws, at present undiscovered; and probably that the genesis of species takes place partly, perhaps mainly, through laws which may be most conveniently spoken of as special powers and tendencies existing in each organism; and partly through influences exerted on each by surrounding conditions and agencies organic and inorganic, terrestrial and cosmical, among which the "survival of the fittest" plays a certain but subordinate part. The theory of "Natural Selection" may (though it need not) be taken in such a way as to lead men to regard the present organic world as formed, so to speak, _accidentally_, beautiful and wonderful as is confessedly the hap-hazard result. The same may perhaps be said with regard to the system advocated by Mr. Herbert Spencer, who, however, also relegates "Natural Selection" to a subordinate _rôle_. The view here advocated, on the other hand, regards the whole organic world as arising and going forward in one harmonious development similar to that which displays itself in the growth and action of each separate individual organism. It also regards each such separate organism as the expression of powers and tendencies not to be {21} accounted for by "Natural Selection" alone, or even by that together with merely the direct influence of surrounding conditions. The difficulties which appear to oppose themselves to the reception of "Natural Selection" or "the survival of the fittest," as the one explanation of the origin of species, have no doubt been already considered by Mr. Darwin. Nevertheless, it may be worth while to enumerate them, and to state the considerations which appear to give them weight; and there is no doubt but that a naturalist so candid and careful as the author of the theory in question, will feel obliged, rather than the reverse, by the suggestion of all the doubts and difficulties which can be brought against it. What is to be brought forward may be summed up as follows:-- That "Natural Selection" is incompetent to account for the incipient stages of useful structures. That it does not harmonize with the co-existence of closely similar structures of diverse origin. That there are grounds for thinking that specific differences may be developed suddenly instead of gradually. That the opinion that species have definite though very different limits to their variability is still tenable. That certain fossil transitional forms are absent, which might have been expected to be present. That some facts of geographical distribution supplement other difficulties. That the objection drawn from the physiological difference between "species" and "races" still exists unrefuted. That there are many remarkable phenomena in organic forms upon which "Natural Selection" throws no light whatever, but the explanations of which, if they could be attained, might throw light upon specific origination. [Page 22] Besides these objections to the sufficiency of "Natural Selection," others may be brought against the hypothesis of "Pangenesis," which, professing as it does to explain great difficulties, seems to do so by presenting others not less great--almost to be the explanation of _obscurum per {23} obscurius_. * * * * * CHAPTER II. THE INCOMPETENCY OF "NATURAL SELECTION" TO ACCOUNT FOR THE INCIPIENT STAGES OF USEFUL STRUCTURES. Mr. Darwin supposes that natural selection acts by slight variations.--These must be useful at once.--Difficulties as to the giraffe; as to mimicry; as to the heads of flat-fishes; as to the origin and constancy of the vertebrate limbs; as to whalebone; as to the young kangaroo; as to sea-urchins; as to certain processes of metamorphosis; as to the mammary gland; as to certain ape characters; as to the rattlesnake and cobra; as to the process of formation of the eye and ear; as to the fully developed condition of the eye and ear; as to the voice; as to shell-fish; as to orchids; as to ants.--The necessity for the simultaneous modification of many individuals.--Summary and conclusion. "Natural Selection," simply and by itself, is potent to explain the maintenance or the further extension and development of favourable variations, which are at once sufficiently considerable to be useful from the first to the individual possessing them. But Natural Selection utterly fails to account for the conservation and development of the minute and rudimentary beginnings, the slight and infinitesimal commencements of structures, however useful those structures may afterwards become. Now, it is distinctly enunciated by Mr. Darwin, that the spontaneous variations upon which his theory depends are individually slight, minute, and insensible. He says,[15] "Slight individual differences, however, {24} suffice for the work, and are probably the sole differences which are effective in the production of new species." And again, after mentioning the frequent sudden appearances of domestic varieties, he speaks of "the false belief as to the similarity of natural species in this respect."[16] In his work on the "Origin of Species," he also observes, "Natural Selection acts only by the preservation and accumulation of small inherited modifications."[17] And "Natural Selection, if it be a true principle, will banish the belief ... of any great and sudden modification in their structure."[18] Finally, he adds, "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down."[19] Now the conservation of minute variations in many instances is, of course, plain and intelligible enough; such, _e.g._, as those which tend to promote the destructive faculties of beasts of prey on the one hand, or to facilitate the flight or concealment of the animals pursued on the other; provided always that these minute beginnings are of such a kind as really to have a certain efficiency, however small, in favour of the conservation of the individual possessing them; and also provided that no unfavourable peculiarity in any other direction accompanies and neutralizes, in the struggle for life, the minute favourable variation. But some of the cases which have been brought forward, and which have met with very general acceptance, seem less satisfactory when carefully analysed than they at first appear to be. Amongst these we may mention "the neck of the giraffe." At first sight it would seem as though a better example in support of "Natural Selection" could hardly have been chosen. Let the fact of the {25} occurrence of occasional, severe droughts in the country which that animal has inhabited be granted. In that case, when the ground vegetation has been consumed, and the trees alone remain, it is plain that at such times only those individuals (of what we assume to be the nascent giraffe species) which were able to reach high up would be preserved, and would become the parents of the following generation, some individuals of which would, of course, inherit that high-reaching power which alone preserved their parents. Only the high-reaching issue of these high-reaching individuals would again, _cæteris paribus_, be preserved at the next drought, and would again transmit to their offspring their still loftier stature; and so on, from period to period, through æons of time, all the individuals tending to revert to the ancient shorter type of body, being ruthlessly destroyed at the occurrence of each drought. (1.) But against this it may be said, in the first place, that the argument proves too much; for, on this supposition, many species must have tended to undergo a similar modification, and we ought to have at least several forms, similar to the giraffe, developed from different Ungulata.[20] A careful observer of animal life, who has long resided in South Africa, explored the interior, and lived in the giraffe country, has assured the Author that the giraffe has powers of locomotion and endurance fully equal to those possessed by any of the other Ungulata of that continent. It would seem, therefore, that some of these other Ungulates ought to have developed in a similar manner as to the neck, under pain of being starved, when the long neck of the giraffe was in its incipient stage. To this criticism it has been objected that different kinds of animals are preserved, in the struggle for life, in very different ways, and even {26} that "high reaching" may be attained in more modes than one--as, for example, by the trunk of the elephant. This is, indeed, true, but then none of the African Ungulata[21] have, nor do they appear ever to have had, any proboscis whatsoever; nor have they acquired such a development as to allow them to rise on their hind limbs and graze on trees in a kangaroo-attitude, nor a power of climbing, nor, as far as known, any other modification tending to compensate for the comparative shortness of the neck. Again, it may perhaps be said that leaf-eating forms are exceptional, and that therefore the struggle to attain high branches would not affect many Ungulates. But surely, when these severe droughts necessary for the theory occur, the ground vegetation is supposed to be exhausted; and, indeed, the giraffe is quite capable of feeding from off the ground. So that, in these cases, the other Ungulata _must_ have taken to leaf eating or have starved, and thus must have had any accidental long-necked varieties favoured and preserved exactly as the long-necked varieties of the giraffe are supposed to have been favoured and preserved. The argument as to the different modes of preservation has been very well put by Mr. Wallace,[22] in reply to the objection that "colour, being dangerous, should not exist in nature." This objection appears similar to mine; as I say that a giraffe neck, being needful, there should be many animals with it, while the objector noticed by Mr. Wallace says, "a dull colour being needful, all animals should be so coloured." And Mr. Wallace shows in reply how porcupines, tortoises and mussels, very hard-coated bombadier beetles, stinging insects and nauseous-tasted caterpillars, can afford to be brilliant by the various means of active defence or passive protection they possess, other than obscure colouration. He says "the {27} attitudes of some insects may also protect them, as the habit of turning up the tail by the harmless rove-beetles (Staphylinidæ) no doubt leads other animals, besides children, to the belief that they can sting. The curious attitude assumed by sphinx caterpillars is probably a safeguard, as well as the blood-red tentacles which can suddenly be thrown out from the neck by the caterpillars of all the true swallow-tailed butterflies." But, because many different kinds of animals can elude the observation or defy the attack of enemies in a great variety of ways, it by no means follows that there are any similar number and variety of ways for attaining vegetable food in a country where all such food, other than the lofty branches of trees, has been for a time destroyed. In such a country we have a number of vegetable-feeding Ungulates, all of which present minute variations as to the length of the neck. If, as Mr. Darwin contends, the natural selection of these favourable variations has alone lengthened the neck of the giraffe by preserving it during droughts; similar variations, in similarly-feeding forms, at the same times, ought similarly to have been preserved and so lengthened the neck of some other Ungulates by similarly preserving them during the same droughts. (2.) It may be also objected, that the power of reaching upwards, acquired by the lengthening of the neck and legs, must have necessitated a considerable increase in the entire size and mass of the body (larger bones requiring stronger and more voluminous muscles and tendons, and these again necessitating larger nerves, more capacious blood-vessels, &c.), and it is very problematical whether the disadvantages thence arising would not, in times of scarcity, more than counterbalance the advantages. For a considerable increase in the supply of food would be requisite on account of this increase in size and mass, while at the same time there would be a certain decrease in strength; for, as Mr. Herbert Spencer {28} says,[23] "It is demonstrable that the excess of absorbed over expended nutriment must, other things equal, become less as the size of an animal becomes greater. In similarly-shaped bodies, the masses vary as the cubes of the dimensions; whereas the strengths vary as the squares of the dimensions.".... "Supposing a creature which a year ago was one foot high, has now become two feet high, while it is unchanged in proportions and structure--what are the necessary concomitant changes that have taken place in it? It is eight times as heavy; that is to say, it has to resist eight times the strain which gravitation puts on its structure; and in producing, as well as in arresting, every one of its movements, it has to overcome eight times the inertia. Meanwhile, the muscles and bones have severally increased their contractile and resisting powers, in proportion to the areas of their transverse sections; and hence are severally but four times as strong as they were. Thus, while the creature has doubled in height, and while its ability to overcome forces has quadrupled, the forces it has to overcome have grown eight times as great. Hence, to raise its body through a given space, its muscles have to be contracted with twice the intensity, at a double cost of matter expended." Again, as to the cost at which nutriment is distributed through the body, and effete matters removed from it, "Each increment of growth being added at the periphery of an organism, the force expended in the transfer of matter must increase in a rapid progression--a progression more rapid than that of the mass." There is yet another point. Vast as may have been the time during which the process of evolution has continued, it is nevertheless not infinite. Yet, as every kind, on the Darwinian hypothesis, varies slightly but indefinitely in every organ and every part of every organ, how very generally must favourable variations as to the length of the neck have {29} been accompanied by some unfavourable variation in some other part, neutralizing the action of the favourable one, the latter, moreover, only taking effect during these periods of drought! How often must not individuals, favoured by a slightly increased length of neck, have failed to enjoy the elevated foliage which they had not strength or endurance to attain; while other individuals, exceptionally robust, could struggle on yet further till they arrived at vegetation within their reach. However, allowing this example to pass, many other instances will be found to present great difficulties. Let us take the cases of mimicry amongst lepidoptera and other insects. Of this subject Mr. Wallace has given a most interesting and complete account,[24] showing in how many and strange instances this superficial resemblance by one creature to some other quite distinct creature acts as a safeguard to the first. One or two instances must here suffice. In South America there is a family of butterflies, termed _Heliconidæ_, which are very conspicuously coloured and slow in flight, and yet the individuals abound in prodigious numbers, and take no precautions to conceal themselves, even when at rest, during the night. Mr. Bates (the author of the very interesting work "The Naturalist on the River Amazons," and the discoverer of "Mimicry") found that these conspicuous butterflies had a very strong and disagreeable odour; so much so that any one handling them and squeezing them, as a collector must do, has his fingers stained and so infected by the smell, as to require time and much trouble to remove it. It is suggested that this unpleasant quality is the cause of the abundance of the Heliconidæ; Mr. Bates and other observers reporting that they have never seen them attacked by the birds, reptiles, or insects which prey upon other lepidoptera. Now it is a curious fact that very different South American butterflies{30} put on, as it were, the exact dress of these offensive beauties and mimic them even in their mode of flight. In explaining the mode of action of this protecting resemblance Mr. Wallace observes:[25] "Tropical insectivorous birds very frequently sit on dead branches of a lofty tree, or on those which overhang forest paths, gazing intently around, and darting off at intervals to seize an insect at a considerable distance, with which they generally return to their station to devour. If a bird began by capturing the slow-flying conspicuous Heliconidæ, and found them always so disagreeable that it could not eat them, it would after a very few trials leave off catching them at all; and their whole appearance, form, colouring, and mode of flight is so peculiar, that there can be little doubt birds would soon learn to distinguish them at a long distance, and never waste any time in pursuit of them. Under these circumstances, it is evident that any other butterfly of a group which birds were accustomed to devour, would be almost equally well protected by closely resembling a Heliconia externally, as if it acquired also the disagreeable odour; always supposing that there were only a few of them among a great number of Heliconias." "The approach in colour and form to the Heliconidæ, however, would be at the first a positive, though perhaps a slight, advantage; for although at short distances this variety would be easily distinguished and devoured, yet at a longer distance it might be mistaken for one of the uneatable group, and so be passed by and gain another day's life, which might in many cases be sufficient for it to lay a quantity of eggs and leave a numerous progeny, many of which would inherit the peculiarity which had been the safeguard of their parent." [Illustration: LEAF BUTTERFLY IN FLIGHT AND REPOSE. (_From Mr. Wallace's_ "_Malay Archipelago._")] As a complete example of mimicry Mr. Wallace refers to a common Indian butterfly. He says:[26] "But the most wonderful and undoubted case of protective resemblance in a butterfly, which I have ever seen, is that {31} of the common Indian _Kallima inachis_, and its Malayan ally, _Kallima paralekta_. The upper surface of these is very striking and showy, as they are of a large size, and are adorned with a broad band of rich orange {32} on a deep bluish ground. The under side is very variable in colour, so that out of fifty specimens no two can be found exactly alike, but every one of them will be of some shade of ash, or brown, or ochre, such as are found among dead, dry, or decaying leaves. The apex of the upper wings is produced into an acute point, a very common form in the leaves of tropical shrubs and trees, and the lower wings are also produced into a short narrow tail. Between these two points runs a dark curved line exactly representing the midrib of a leaf, and from this radiate on each side a few oblique lines, which serve to indicate the lateral veins of a leaf. These marks are more clearly seen on the outer portion of the base of the wings, and on the inner side towards the middle and apex, and it is very curious to observe how the usual marginal and transverse striæ of the group are here modified and strengthened so as to become adapted for an imitation of the venation of a leaf." ... "But this resemblance, close as it is, would be of little use if the habits of the insect did not accord with it. If the butterfly sat upon leaves or upon flowers, or opened its wings so as to expose the upper surface, or exposed and moved its head and antennæ as many other butterflies do, its disguise would be of little avail. We might be sure, however, from the analogy of many other cases, that the habits of the insect are such as still further to aid its deceptive garb; but we are not obliged to make any such supposition, since I myself had the good fortune to observe scores of _Kallima paralekta_, in Sumatra, and to capture many of them, and can vouch for the accuracy of the following details. These butterflies frequent dry forests, and fly very swiftly. They were seen to settle on a flower or a green leaf, but were many times lost sight of in a bush or tree of dead leaves. On such occasions they were generally searched for in vain, for while gazing intently at the very spot where one had disappeared, it would often suddenly dart out, and again vanish twenty or fifty yards further on. On one or two occasions the insect was detected{33} reposing, and it could then be seen how completely it assimilates itself to the surrounding leaves. It sits on a nearly upright twig, the wings fitting closely back to back, concealing the antennæ and head, which are drawn up between their bases. The little tails of the hind wing touch the branch, and form a perfect stalk to the leaf, which is supported in its place by the claws of the middle pair of feet, which are slender and inconspicuous. The irregular outline of the wings gives exactly the perspective effect of a shrivelled leaf. We thus have size, colour, form, markings, and habits, all combining together to produce a disguise which may be said to be absolutely perfect; and the protection which it affords is sufficiently indicated by the abundance of the individuals that possess it." Beetles also imitate bees and wasps, as do some Lepidoptera; and objects the most bizarre and unexpected are simulated, such as dung and drops of dew. Some insects, called bamboo and walking-stick insects, have a most remarkable resemblance to pieces of bamboo, to twigs and branches. Of these latter insects Mr. Wallace says:[27] "Some of these are a foot long and as thick as one's finger, and their whole colouring, form, rugosity, and the arrangement of the head, legs, and antennæ, are such as to render them absolutely identical in appearance with dry sticks. They hang loosely about shrubs in the forest, and have the extraordinary habit of stretching out their legs unsymmetrically, so as to render the deception more complete." Now let us suppose that the ancestors of these various animals were all destitute of the very special protections they at present possess, as on the Darwinian hypothesis we must do. Let it also be conceded that small deviations from the antecedent colouring or form would tend to make some of their ancestors escape destruction by causing them more or less frequently to be passed over, or mistaken by their persecutors. Yet the deviation {34} must, as the event has shown, in each case be in some definite direction, whether it be towards some other animal or plant, or towards some dead or inorganic matter. But as, according to Mr. Darwin's theory, there is a constant tendency to indefinite variation, and as the minute incipient variations will be in _all directions_, they must tend to neutralize each other, and at first to form such unstable modifications that it is difficult, if not impossible, to see how such indefinite oscillations of infinitesimal beginnings can ever build up a sufficiently appreciable resemblance to a leaf, bamboo, or other object, for "Natural Selection" to seize upon and perpetuate. This difficulty is augmented when we consider--a point to be dwelt upon hereafter--how necessary it is that many individuals should be similarly modified simultaneously. This has been insisted on in an able article in the _North British Review_ for June 1867, p. 286, and the consideration of the article has occasioned Mr. Darwin to make an important modification in his views.[28] In these cases of mimicry it seems difficult indeed to imagine a reason why variations tending in an _infinitesimal degree_ in any special direction should be preserved. All variations would be preserved which tended to obscure the perception of an animal by its enemies, whatever direction those variations might take, and the common preservation of conflicting tendencies would greatly favour their mutual neutralization and obliteration if we may rely on the many cases recently brought forward by Mr. Darwin with regard to domestic animals. [Illustration: THE WALKING-LEAF INSECT.] Mr. Darwin explains the imitation of some species by others more or less nearly allied to it, by the common origin of both the mimic and the mimicked species, and the consequent possession by both (according to the theory of "Pangenesis") of gemmules tending to reproduce ancestral characters, which characters the mimic must be assumed first to have {35} lost and then to have recovered. Mr. Darwin says,[29] "Varieties of one species frequently mimic distinct species, a fact in perfect harmony with the foregoing cases, and explicable _only on the theory of descent_." But this at the best is but a partial and very incomplete explanation. It is one, moreover, which Mr. Wallace does not accept.[30] It is very incomplete, because it has no bearing on some of the most striking cases, and of course Mr. Darwin does not pretend that it has. We should have to go back far indeed to reach the common ancestor of the mimicking {36} walking-leaf insect and the real leaf it mimics, or the original progenitor of both the bamboo insect and the bamboo itself. As these last most remarkable cases have certainly nothing to do with heredity,[31] it is unwarrantable to make use of that explanation for other protective resemblances, seeing that its inapplicability, in certain instances, is so manifest. Again, at the other end of the process it is as difficult to account for the last touches of perfection in the mimicry. Some insects which imitate leaves extend the imitation even to the very injuries on those leaves made by the attacks of insects or of fungi. Thus, speaking of one of the walking-stick insects, Mr. Wallace says:[32] "One of these creatures obtained by myself in Borneo (_Ceroxylus laceratus_) was covered over with foliaceous excrescences of a clear olive-green colour, so as exactly to resemble a stick grown over by a creeping moss or jungermannia. The Dyak who brought it me assured me it was grown over with moss although alive, and it was only after a most minute examination that I could convince myself it was not so." Again, as to the leaf butterfly, he says:[33] "We come to a still more extraordinary part of the imitation, for we find representations of leaves in every stage of decay, variously blotched, and mildewed, and pierced with holes, and in many cases irregularly covered with powdery black dots, gathered into patches and spots, so closely resembling the various kinds of minute fungi that grow on dead leaves, that it is impossible to avoid thinking at first sight that the butterflies themselves have been attacked by real fungi." Here imitation has attained a development which seems utterly beyond the power of the mere "survival of the fittest" to produce. How this double mimicry can importantly aid in the struggle for life seems puzzling indeed, but much more so how the first faint beginnings of the imitation of {37} such injuries in the leaf can be developed in the animal into such a complete representation of them--_a fortiori_ how simultaneous and similar first beginnings of imitations of such injuries could ever have been developed in several individuals, out of utterly indifferent and indeterminate infinitesimal variations in all conceivable directions. [Illustration: PLEURONECTIDÆ, WITH THE PECULIARLY PLACED EYE IN DIFFERENT POSITIONS. (_From Dr. Traquair's paper in the "Transactions of the Linnean Society, 1865."_)] Another instance which may be cited is the asymmetrical condition of the heads of the flat-fishes (Pleuronectidæ), such as the sole, the flounder, the brill, the turbot, &c. In all these fishes the two eyes, which in the young are situated as usual one on each side, come to be placed, in the adult, both on the same side of the head. If this condition had appeared at once, if in the hypothetically fortunate common ancestor of these fishes an eye had suddenly become thus transferred, then the perpetuation of such a transformation by the action of "Natural Selection" is conceivable enough. Such sudden changes, however, are not those favoured by the Darwinian theory, and indeed the accidental occurrence of such a spontaneous transformation is hardly conceivable. But if this is not so, if the transit was gradual, then how such transit of one eye a minute fraction of the {38} journey towards the other side of the head could benefit the individual is indeed far from clear. It seems, even, that such an incipient transformation must rather have been injurious. Another point with regard to these flat-fishes is that they appear to be in all probability of recent origin--_i.e._ geologically speaking. There is, of course, no great stress to be laid on the mere absence of their remains from the secondary strata, nevertheless that absence is noteworthy, seeing that existing fish families, _e.g._ sharks (Squalidæ), have been found abundantly even down so far as the carboniferous rocks, and traces of them in the Upper Silurian. Another difficulty seems to be the first formation of the limbs of the higher animals. The lowest Vertebrata[34] are perfectly limbless, and if, as most Darwinians would probably assume, the primeval vertebrate creature was also apodal, how are the preservation and development of the first rudiments of limbs to be accounted for--such rudiments being, on the hypothesis in question, infinitesimal and functionless? In reply to this it has been suggested that a mere flattening of the end of the body has been useful, such, _e.g._, as we see in sea-snakes,[35] which may be the rudiment of a tail formed strictly to aid in swimming. Also that a mere _roughness_ of the skin might be useful to a swimming animal by holding the water better, that thus minute processes might be selected and preserved, and that, in the same way, these might be gradually increased into limbs. But it is, to say the least, very questionable whether a roughness of the skin, or minute processes, would be useful to a {39} swimming animal; the motion of which they would as much impede as aid, unless they were at once capable of a suitable and appropriate action, which is against the hypothesis. Again, the change from mere indefinite and accidental processes to two regular pairs of symmetrical limbs, as the result of merely fortuitous, favouring variations, is a step the feasibility of which hardly commends itself to the reason, seeing the very different positions assumed by the ventral fins in different fishes. If the above suggestion made in opposition to the views here asserted be true, then the general constancy of position of the limbs of vertebrata may be considered as due to the position assumed by the primitive rugosities from which those limbs were generated. Clearly only two pairs of rugosities were so preserved and developed, and all limbs (on this view) are descendants of the same two pairs, as all have so similar a fundamental structure. Yet we find in many fishes the pair of fins, which correspond to the hinder limbs of other animals, placed so far forwards as to be either on the same level with, or actually in front of, the normally anterior pair of limbs; and such fishes are from this circumstance called "thoracic," or "jugular" fishes respectively, as the weaver fishes and the cod. This is a wonderful contrast to the fixity of position of vertebrate limbs generally. If then such a change can have taken place in the comparatively short time occupied by the evolution of these special fish forms, we might certainly expect other and far more bizarre structures would (did not some law forbid) have been developed, from other rugosities, in the manifold exigencies of the multitudinous organisms which must (on the Darwinian hypothesis) have been gradually evolved during the enormous period intervening between the first appearance of vertebrate life and the present day. Yet, with these exceptions, the position of the limbs is constant from the lower fishes up to man, there being always an anterior pectoral pair placed in front of a posterior or pelvic pair when both are present, and in no single {40} instance are there more than these two pairs. [Illustration: MOUTH OF A WHALE.] The development of whalebone (baleen) in the mouth of the whale is another difficulty. A whale's mouth is furnished with very numerous horny plates, which hang down from the palate along each side of the mouth. They thus form two longitudinal series, each plate of which is placed transversely to the long axis of the body, and all are very close together. On depressing the lower lip the free outer edges of these plates come into view. Their inner edges are furnished with numerous coarse hair-like processes, consisting of some of the constituent fibres of the horny plates--which, as it were, fray out--and the mouth is thus lined, except below, by a network of countless fibres formed by the inner edges of the two series of plates. This network acts as a sort of sieve. When the whale feeds it takes {41} into its mouth a great gulp of water, which it drives out again through the intervals of the horny plates of baleen, the fluid thus traversing the sieve of horny fibres, which retains the minute creatures on which these marine monsters subsist. Now it is obvious, that if this baleen had once attained such a size and development as to be at all useful, then its preservation and augmentation within serviceable limits, would be promoted by "Natural Selection" alone. But how to obtain the beginning of such useful development? There are indeed certain animals of exclusively aquatic habits (the dugong and manatee) which also possess more or less horn on the palate, and at first sight this might be taken as a mitigation of the difficulty; but it is not so, and the fact does not help us one step further along the road: for, in the first place, these latter animals differ so importantly in structure from whales and porpoises that they form an altogether distinct order, and cannot be thought to approximate to the whale's progenitors. They are vegetarians, the whales feed on animals; the former never have the ribs articulated in the mode in which they are in some of the latter; the former have pectoral mammæ, and the latter are {42} provided with two inguinal mammary glands, and have the nostrils enlarged into blowers, which the former have not. The former thus constitute the order Sirenia, while the latter belong to the Cetacea. In the second place, the horny matter on the palates of the dugong and manatee has not, even initially, that "strainer" action, which is the characteristic function of the Cetacean "baleen." [Illustration: FOUR PLATES OF BALEEN SEEN OBLIQUELY FROM WITHIN.] [Illustration: DUGONG.] There is another very curious structure, the origin or the disappearance of which it seems impossible to account for on the hypothesis of minute indefinite variations. It is that of the mouth of the young kangaroo. In all mammals, as in ourselves, the air-passage from the lungs opens in the floor of the mouth behind the tongue, and in front of the opening of the gullet, so that each particle of food as it is swallowed passes over the opening, but is prevented from falling into it (and thus causing death from choking) by the action of a small cartilaginous shield (the epiglottis), which at the right moment bends back and protects the orifice. Now the kangaroo is born in such an exceedingly imperfect and undeveloped condition, that it is quite unable to suck. The mother therefore places the minute blind and naked young upon the nipple, and then injects milk into it by means of a special muscular envelope of the mammary gland. Did no special provision exist, the young one must infallibly be choked by the intrusion of the milk into the windpipe. But there _is_ a special provision. The larynx is so elongated that it rises up into the posterior end of the nasal passage, and is thus enabled to give free entrance to the air for the lungs, while the milk passes harmlessly on each side of this elongated larynx, and so safely attains the gullet behind it. Now, on the Darwinian hypothesis, either all mammals descended from marsupial progenitors, or else the marsupials, sprung from animals having in most respects the ordinary mammalian structure. [Page 43] On the first alternative, how did "Natural Selection" remove this (at least perfectly innocent and harmless) structure in almost all other mammals, and, having done so, again reproduce it in precisely those forms which alone require it, namely, the Cetacea? That such a harmless structure _need not_ be removed any Darwinian must confess, since a structure exists in both the crocodiles and gavials, which enables the former to breathe themselves while drowning the prey which they hold in their mouths. On Mr. Darwin's hypothesis it could only have been developed where useful, therefore not in the gavials(!) which feed on fish, but which yet retain, as we might expect, this, in them superfluous but harmless formation. On the second alternative, how did the elongated larynx itself arise, seeing that if its development lagged behind that of the maternal structure, the young primeval kangaroo must be choked: while without the injecting power in the mother, it must be starved? The struggle by the sole action of which such a form was developed must indeed have been severe! [Illustration: AN ECHINUS, OR SEA-URCHIN (The spines removed from one-half.)] The sea-urchins (Echinus) present us also with structures the origin of which it seems impossible to explain by the action of "Natural {44} Selection" only. These lowly animals belong to that group of the star-fish class (Echinodermata), the species of which possess generally spheroidal bodies, built up of multitudinous calcareous plates, and constitute the order Echinoidea. They are also popularly known as sea-eggs. Utterly devoid of limbs, the locomotion of these creatures is effected by means of rows of small tubular suckers (which protrude through pores in the calcareous plates) and by moveable spines scattered over the body. [Illustration: PEDICELLARIÆ. (Immensely enlarged.)] Besides these spines and suckers there are certain very peculiar structures, termed "Pedicellariæ." Each of these consists of a long slender stalk, ending in three short limbs--or rather jaws--the whole supported by a delicate internal skeleton. The three limbs (or jaws), which start from a common point at the end of the stalk, are in the constant habit of opening and closing together again with a snapping action, while the stalk itself sways about. The utility of these appendages is, even now, problematical. It may be that they remove from the surface of the animal's body foreign substances which would be prejudicial to it, and which it cannot otherwise get rid of. But granting this, what would be the utility of the _first rudimentary beginnings_ of such structures, and how could such incipient buddings have ever preserved the life of a single Echinus? It is true that on Darwinian principles the ancestral form from which the sea-urchin developed was different, and must not be conceived merely as an Echinus devoid of pedicellariæ; but this makes the difficulty none the less. It is equally hard to imagine that the first rudiments of such structures could have been useful to _any_ animal from which the Echinus might have been{45} derived. Moreover, not even the _sudden_ development of the snapping action could have been beneficial without the freely moveable stalk, nor could the latter have been efficient without the snapping jaws, yet no minute merely indefinite variations could simultaneously evolve these complex co-ordinations of structure; to deny this seems to do no less than to affirm a startling paradox. Mr. Darwin explains the appearance of some structures, the utility of which is not apparent, by the existence of certain "laws of correlation." By these he means that certain parts or organs of the body are so related to other organs or parts, that when the first are modified by the action of "Natural Selection," or what not, the second are simultaneously affected, and increase proportionally or possibly so decrease. Examples of such are the hair and teeth in the naked Turkish dog, the general deafness of white cats with blue eyes, the relation between the presence of more or less down on young birds when first hatched, and the future colour of their plumage,[36] with many others. But the idea that the modification of any internal or external part of the body of an Echinus carries with it the effect of producing elongated, flexible, triradiate, snapping processes, is, to say the very least, fully as obscure and mysterious as what is here contended for, viz. the efficient presence of an unknown internal natural law or laws conditioning the evolution of new specific forms from preceding ones, modified by the action of surrounding conditions, by "Natural Selection" and by other controlling influences. The same difficulty seems to present itself in other examples of exceptional structure and action. In the same Echinus, as in many allied forms, and also in some more or less remote ones, a very peculiar mode of development exists. The adult is not formed from the egg directly, but {46} the egg gives rise to a creature which swims freely about, feeds, and is even somewhat complexly organized. Soon a small lump appears on one side of its stomach; this enlarges, and, having established a communication with the exterior, envelopes and appropriates the creature's stomach, with which it swims away and develops into the complete adult form, while the dispossessed individual perishes. Again, certain flies present a mode of development equally bizarre, though quite different. In these flies, the grub is, as usual, produced from the ovum, but this grub, instead of growing up into the adult in the ordinary way, undergoes a sort of liquefaction of a great part of its body, while certain patches of formative tissue, which are attached to the ramifying air tubes, or tracheæ (and which patches bear the name of "imaginal disks"), give rise to the legs, wings, eyes, &c., respectively; and these severally formed parts grow together, and build up the head and body by their mutual approximation. Such a process is unknown outside the class of insects, and inside that class it is only known in a few of the two-winged flies. Now, how "Natural Selection," or any "laws of correlation," can account for the gradual development of such an exceptional process of development--so extremely divergent from that of other insects--seems nothing less than inconceivable. Mr. Darwin himself[37] gives an account of a very peculiar and abnormal mode of development of a certain beetle, the sitaris, as described by M. Fabre. This insect, instead of at first appearing in its grub stage, and then, after a time, putting on the adult form, is at first active and furnished with six legs, two long antennæ, and four eyes. Hatched in the nests of bees, it at first attaches itself to one of the males, and then crawls, when the opportunity offers, upon a female bee. When the female bee lays her eggs, the young sitaris springs upon them and devours them. Then, losing its eyes, legs, and antennæ, and {47} becoming rudimentary, it sinks into an ordinary grub-like form, and feeds on honey, ultimately undergoing another transformation, re-acquiring its legs, &c., and emerging a perfect beetle! That such a process should have arisen by the accumulation of minute accidental variations in structure and habit, appears to many minds, quite competent to form an opinion on the subject, absolutely incredible. It may be objected, perhaps, that these difficulties are _difficulties of ignorance_--that we cannot explain them because we do not know _enough_ of the animals. But it is here contended that this is not the case; it is not that we merely fail to see how Natural Selection acted, but that there is a positive incompatibility between the cause assigned and the results. It will be stated shortly what wonderful instances of co-ordination and of unexpected utility Mr. Darwin has discovered in orchids. The discoveries are not disputed or undervalued, but the explanation of their _origin_ is deemed thoroughly unsatisfactory--utterly insufficient to explain the incipient, infinitesimal beginnings of structures which are of utility only when they are considerably developed. Let us consider the mammary gland, or breast. Is it conceivable that the young of any animal was ever saved from destruction by accidentally sucking a drop of scarcely nutritious fluid from an accidentally hypertrophied cutaneous gland of its mother? And even if one was so, what chance was there of the perpetuation of such a variation? On the hypothesis of Natural Selection itself, we must assume that up to that time the race had been well adapted to the surrounding conditions; the temporary and accidental trial and change of conditions, which caused the so-sucking young one to be the "fittest to survive" under the supposed circumstances, would soon cease to act, and then the progeny of the mother, with the accidentally hypertrophied, sebaceous glands, would have no tendency to survive the {48} far outnumbering descendants of the normal ancestral form. If, on the other hand, we assume the change of conditions not to have been temporary but permanent, and also assume that this permanent change of conditions was accidentally synchronous with the change of structure, we have a coincidence of very remote probability indeed. But if, again, we accept the presence of some harmonizing law simultaneously determining the two changes, or connecting the second with the first by causation, then, of course, we remove the accidental character of the coincidence. Again, how explain the external position of the male sexual glands in certain mammals? The utility of the modification, when accomplished, is problematical enough, and no less so the incipient stages of the descent. As was said in the first chapter, Mr. Darwin explains the brilliant plumage of the peacock or the humming-bird by the action of sexual selection: the more and more brilliant males being selected by the females (which are thus attracted) to become the fathers of the next generation, to which generation they tend to communicate their own bright nuptial vesture. But there are peculiarities of colour and of form which it is exceedingly difficult to account for by any such action. Thus, amongst apes, the female is notoriously weaker, and is armed with much less powerful canine tusks than the male. When we consider what is known of the emotional nature of these animals, and the periodicity of its intensification, it is hardly credible that a female would often risk life or limb through her admiration of a trifling shade of colour, or an infinitesimally greater though irresistibly fascinating degree of wartiness.[38] {49} [Illustration: RATTLESNAKE.] Yet the males of some kinds of ape are adorned with quite exceptionally brilliant local decoration, and the male orang is provided with remarkable, projecting, warty lumps of skin upon the cheeks. As we have said, the weaker female can hardly be supposed to have developed these by persevering and long-continued selection, nor can they be thought to tend to the preservation of the individual. On the contrary, the presence of this enlarged appendage must occasion a slight increase in the need of nutriment, and in so far must be a detriment, although its detrimental effect would not be worth speaking of except in relation to "Darwinism," according to which, "selection" has acted through unimaginable ages, {50} and has ever tended to suppress any useless development by the struggle for life.[39] [Illustration: COBRA. (_Copied, by permission, from Sir Andrew Smith's "Reptiles of South Africa."_)] In poisonous serpents, also, we have structures which, at all events at first sight, seem positively hurtful to those reptiles. Such are the rattle of the rattlesnake, and the expanding neck of the cobra, the former seeming to warn the ear of the intended victim, as the latter warns the eye. It is true we cannot perhaps demonstrate that the victims are alarmed and warned, but, on Darwinian principles, they certainly ought to be so. For the {51} rashest and most incautious of the animals preyed on would always tend to fall victims, and the existing individuals being the long-descended progeny of the timid and cautious, ought to have an inherited tendency to distrust, amongst other things, both "rattling" and "expanding" snakes. As to any power of fascination exercised by means of these actions, the most distinguished naturalists, certainly the most distinguished erpetologists, entirely deny it, and it is opposed to the careful observations of those known to us.[40] The mode of formation of both the eye and the ear of the highest animals is such that, if it is (as most Darwinians assert processes of development to be) a record of the actual steps by which such structures were first evolved in antecedent forms, it almost amounts to a demonstration that those steps were never produced by "Natural Selection." The eye is formed by a simultaneous and corresponding ingrowth of one part and outgrowth of another. The skin in front of the future eye becomes depressed, the depression increases and assumes the form of a sac, which changes into the aqueous humour and lens. An outgrowth of brain substance, on the other hand, forms the retina, while a third process is a lateral ingrowth of connective tissue, which afterwards changes into the vitreous humour of the eye. The internal ear is formed by an involution of the integument, and not by an outgrowth of the brain. But tissue, in connexion with it, becomes in part changed, thus forming the auditory nerve, which places the tegumentary sac in direct communication with the brain itself. {52} Now, these complex and simultaneous co-ordinations could never have been produced by infinitesimal beginnings, since, until so far developed as to effect the requisite junctions, they are useless. But the eye and ear when fully developed present conditions which are hopelessly difficult to reconcile with the mere action of "Natural Selection." The difficulties with regard to the eye have been well put by Mr. Murphy, especially that of the concordant result of visual development springing from different starting-points and continued on by independent roads. He says,[41] speaking of the beautiful structure of the perfect eye, "The higher the organization, whether of an entire organism or of a single organ, the greater is the number of the parts that co-operate, and the more perfect is their co-operation; and consequently, the more necessity there is for corresponding variations to take place in all the co-operating parts at once, and the more useless will be any variation whatever unless it is accompanied by corresponding variations in the co-operating parts; while it is obvious that the greater the number of variations which are needed in order to effect an improvement, the less will be the probability of their all occurring at once. It is no reply to this to say, what is no doubt abstractedly true, that whatever is possible becomes probable, if only time enough be allowed. There are improbabilities so great that the common sense of mankind treats them as impossibilities. It is not, for instance, in the strictest sense of the word, impossible that a poem and a mathematical proposition should be obtained by the process of shaking letters out of a box; but it is improbable to a degree that cannot be distinguished from impossibility; and the improbability of obtaining an improvement in an organ by means of several spontaneous variations, all occurring together, is an improbability of the same kind. If we suppose that any single variation occurs on the average once in _m_ times, the probability of {53} that variation occurring in any individual will be 1/_m_; and suppose that _x_ variations must concur in order to make an improvement, then the probability of the necessary variations all occurring together will be 1/_m_^x. Now suppose, what I think a moderate proposition, that the value of _m_ is 1,000, and the value of _x_ is 10, then 1/_m_^x = 1/1000^{10} = 1/10^{30}. A number about ten thousand times as great as the number of waves of light that have fallen on the earth since historical time began. And it is to be further observed, that no improvement will give its possessor a _certainty_ of surviving and leaving offspring, but only an _extra chance_, the value of which it is quite impossible to estimate." This difficulty is, as Mr. Murphy points out, greatly intensified by the undoubted fact that the wonderfully complex structure has been arrived at quite independently in beasts on the one hand and in cuttle-fishes on the other; while creatures of the insect and crab division present us with a third and quite separately developed complexity. As to the ear, it would take up too much space to describe its internal structure;[42] it must suffice to say that in its interior there is an immense series of minute rod-like bodies, termed _fibres of Corti_, having the appearance of a key-board, and each fibre being connected with a filament of the auditory nerve, these nerves being like strings to be struck by the keys, _i.e._ by the fibres of Corti. Moreover, this apparatus is supposed to be a key-board in function as well as in appearance, the{54} vibration of each one fibre giving rise, it is believed, to the sensation of one particular tone, and combinations of such vibrations producing chords. It is by the action of this complex organ then, that all the wonderful intricacy and beauty of Beethoven and Mozart come, most probably, to be perceived and appreciated. Now it can hardly be contended that the preservation of any race of men in the struggle for life ever depended on such an extreme delicacy and refinement of the internal ear,--a perfection only exercised in the enjoyment and appreciation of the most perfect musical performances. How, then, could either the minute incipient stages, or the final perfecting touches of this admirable structure, have been brought about by vague, aimless, and indefinite variations in all conceivable directions of an organ, suitable to enable the rudest savage to minister to his necessities, but no more? Mr. Wallace[43] makes an analogous remark with regard to the organ of voice in man--the human larynx. He says of singing: "The habits of savages give no indication of how this faculty could have been developed by Natural Selection, because it is never required or used by them. The singing of savages is a more or less monotonous howling, and the females seldom sing at all. Savages certainly never choose their wives for fine voices, but for rude health, and strength, and physical beauty. Sexual selection could not therefore have developed this wonderful power, which only comes into play among civilized people." Reverting once more to beauty of form and colour, there is one manifestation of it for which no one can pretend that sexual selection can possibly account. The instance referred to is that presented by bivalve shell-fish.[44] Here we meet with charming tints and elegant forms and markings of no direct use to their possessors[45] in the struggle for {55} life, and of no indirect utility as regards sexual selection, for fertilization takes place by the mere action of currents of water, and the least beautiful individual has fully as good a chance of becoming a parent as has the one which is the most favoured in beauty of form and colour. Again, the peculiar outline and coloration of certain orchids--notably of our own bee, fly, and spider orchids--seem hardly explicable by any action of "Natural Selection." Mr. Darwin says very little on this singular resemblance of flowers to insects, and what he does say seems hardly to be what an advocate of "Natural Selection" would require. Surely, for minute accidental indefinite variations to have built up such a striking resemblance to insects, we ought to find that the preservation of the plant, or the perpetuation of its race, depends almost constantly on relations between bees, spiders, and flies respectively and the bee, spider, and fly orchids.[46] This process must have continued for ages constantly and perseveringly, and yet what is the fact? Mr. Darwin tells us, in his work on the Fertilization of Orchids, that neither the spider nor the fly orchids are much visited by insects, while, with regard to the bee orchid, he says, "I have never seen an insect visit these flowers." And he shows how this species is even wonderfully and specially modified to effect self-fertilization. In the work just referred to Mr. Darwin gives a series of the most wonderful and minute contrivances by which the visits of insects are utilized for the fertilization of orchids,--structures so wonderful {56} that nothing could well be more so, except the attribution of their origin to minute, fortuitous, and indefinite variation. The instances are too numerous and too long to quote, but in his "Origin of Species"[47] he describes two which must not be passed over. In one (_Coryanthes_) the orchid has its lower lip enlarged into a bucket, above which stand two water-secreting horns. These latter replenish the bucket from which, when half-filled, the water overflows by a spout on one side. Bees visiting the flower fall into the bucket and crawl out at the spout. By the peculiar arrangement of the parts of the flower, the first bee which does so carries away the pollen-mass glued to his back, and then when he has his next involuntary bath in another flower, as he crawls out the pollen-mass attached to him comes in contact with the stigma of that second flower and fertilizes it. In the other example (_Catasetum_), when a bee gnaws a certain part of the flower, he inevitably touches a long delicate projection, which Mr. Darwin calls the antenna. "This antenna transmits a vibration to a certain membrane, which is instantly ruptured; this sets free a spring by which the pollen-mass is shot forth like an arrow in the right direction, and adheres by its viscid extremity to the back of the bee!" Another difficulty, and one of some importance, is presented by those communities of ants which have not only a population of sterile females, or workers, but two distinct and very different castes of such. Mr. Darwin believes that he has got over this difficulty by having found individuals intermediate in form and structure[48] between the two working castes; others may think that we have in this belief of Mr. Darwin, an example {57} of the unconscious action of volition upon credence. A vast number of difficulties similar to those which have been mentioned might easily be cited--those given, however, may suffice. There remains, however, to be noticed a very important consideration, which was brought forward in the _North British Review_ for June 1867, p. 286, namely, the necessity for the simultaneous modification of _many individuals_. This consideration seems to have escaped Mr. Darwin, for at p. 104 of his last (fifth) edition of "Natural Selection," he admits, with great candour, that until reading this article he did not "appreciate how rarely single variations, whether slight or strongly marked, could be perpetuated." The _North British Review_ (speaking of the supposition that a species is changed by the survival of a few individuals in a century through a similar and favourable variation) says: "It is very difficult to see how this can be accomplished, even when the variation is eminently favourable indeed; and still more difficult when the advantage gained is very slight, as must generally be the case. The advantage, whatever it may be, is utterly outbalanced by numerical inferiority. A million creatures are born; ten thousand survive to produce offspring. One of the million has twice as good a chance as any other of surviving; but the chances are fifty to one against the gifted individuals being one of the hundred survivors. No doubt the chances are twice as great against any one other individual, but this does not prevent their being enormously in favour of _some_ average individual. However slight the advantage may be, if it is shared by half the individuals produced, it will probably be present in at least fifty-one of the survivors, and in a larger proportion of their offspring; but the chances are against the preservation of any one 'sport' (_i.e._ sudden, marked variation) in a numerous tribe. The vague use of an imperfectly understood doctrine of chance has led Darwinian supporters, first, to confuse the two cases above distinguished; and, secondly, to imagine {58} that a very slight balance in favour of some individual sport must lead to its perpetuation. All that can be said is that in the above example the favoured sport would be preserved once in fifty times. Let us consider what will be its influence on the main stock when preserved. It will breed and have a progeny of say 100; now this progeny will, on the whole, be intermediate between the average individual and the sport. The odds in favour of one of this generation of the new breed will be, say one and a half to one, as compared with the average individual; the odds in their favour will, therefore, be less than that of their parents; but owing to their greater number, the chances are that about one and a half of them would survive. Unless these breed together, a most improbable event, their progeny would again approach the average individual; there would be 150 of them, and their superiority would be, say in the ratio of one and a quarter to one; the probability would now be that nearly two of them would survive, and have 200 children, with an eighth superiority. Rather more than two of these would survive; but the superiority would again dwindle, until after a few generations it would no longer be observed, and would count for no more in the struggle for life than any of the hundred trifling advantages which occur in the ordinary organs. An illustration will bring this conception home. Suppose a white man to have been wrecked on an island inhabited by negroes, and to have established himself in friendly relations with a powerful tribe, whose customs he has learnt. Suppose him to possess the physical strength, energy, and ability of a dominant white race, and let the food and climate of the island suit his constitution; grant him every advantage which we can conceive a white to possess over the native; concede that in the struggle for existence his chance of a long life will be much superior to that of the native chiefs; yet from all these admissions, there does not follow the conclusion that, after a limited or unlimited {59} number of generations, the inhabitants of the island will be white. Our shipwrecked hero would probably become king; he would kill a great many blacks in the struggle for existence; he would have a great many wives and children." ... "In the first generation there will be some dozens of intelligent young mulattoes, much superior in average intelligence to the negroes. We might expect the throne for some generations to be occupied by a more or less yellow king; but can any one believe that the whole island will gradually acquire a white, or even a yellow, population?" "Darwin says that in the struggle for life a grain may turn the balance in favour of a given structure, which will then be preserved. But one of the weights in the scale of nature is due to the number of a given tribe. Let there be 7000 A's and 7000 B's, representing two varieties of a given animal, and let all the B's, in virtue of a slight difference of structure, have the better chance of life by 1/7000 part. We must allow that there is a slight probability that the descendants of B will supplant the descendants of A; but let there be only 7001 A's against 7000 B's at first, and the chances are once more equal, while if there be 7002 A's to start, the odds would be laid on the A's. True, they stand a greater chance of being killed; but then they can better afford to be killed. The grain will only turn the scales when these are very nicely balanced, and an advantage in numbers counts for weight, even as an advantage in structure. As the numbers of the favoured variety diminish, so must its relative advantages increase, if the chance of its existence is to surpass the chance of its extinction, until hardly any conceivable advantage would enable the descendants of a single pair to exterminate the descendants of many thousands if they and their descendants are supposed to breed freely with the inferior variety, and so gradually lose their ascendency." Mr. Darwin himself says of the article quoted: "The justice of these remarks cannot, I think, be disputed. If, for instance, a bird of some {60} kind could procure its food more easily by having its beak curved, and if one were born with its beak strongly curved, and which consequently flourished, nevertheless there would be a very poor chance of this one individual perpetuating its kind to the exclusion of the common form." This admission seems almost to amount to a change of front in the face of the enemy! These remarks have been quoted at length because they so greatly intensify the difficulties brought forward in this chapter. If the most favourable variations have to contend with such difficulties, what must be thought as to the chance of preservation of the slightly displaced eye in a sole or of the incipient development of baleen in a whale? SUMMARY AND CONCLUSION. It has been here contended that a certain few facts, out of many which might have been brought forward, are inconsistent with the origination of species by "Natural Selection" only or mainly. Mr. Darwin's theory requires minute, indefinite, fortuitous variations of all parts in all directions, and he insists that the sole operation of "Natural Selection" upon such is sufficient to account for the great majority of organic forms, with their most complicated structures, intricate mutual adaptations and delicate adjustments. To this conception has been opposed the difficulties presented by such a structure as the form of the giraffe, which ought not to have been the solitary structure it is; also the minute beginnings and the last refinements of protective mimicry equally difficult or rather impossible to account for by "Natural Selection." Again the difficulty as to the heads of flat-fishes has been insisted on, as also the origin, and at the same time the constancy, of the limbs of the highest animals. Reference has also been made to the whalebone of whales, and to the impossibility of {61} understanding its origin through "Natural Selection" only; the same as regards the infant kangaroo, with its singular deficiency of power compensated for by maternal structures on the one hand, to which its own breathing organs bear direct relation on the other. Again, the delicate and complex pedicellariæ of Echinoderms, with a certain process of development (through a secondary larva) found in that class, together with certain other exceptional modes of development, have been brought forward. The development of colour in certain apes, the hood of the cobra, and the rattle of the rattlesnake have also been cited. Again, difficulties as to the process of formation of the eye and ear, and as to the fully developed condition of those complex organs, as well as of the voice, have been considered. The beauty of certain shell-fish; the wonderful adaptations of structure, and variety of form and resemblance, found in orchids; together with the complex habits and social conditions of certain ants, have been hastily passed in review. When all these complications are duly weighed and considered, and when it is borne in mind how necessary it is for the permanence of a new variety that many individuals in each case should be simultaneously modified, the cumulative argument seems irresistible. The Author of this book can say that though by no means disposed originally to dissent from the theory of "Natural Selection," if only its difficulties could be solved, he has found each successive year that deeper consideration and more careful examination have more and more brought home to him the inadequacy of Mr. Darwin's theory to account for the preservation and intensification of incipient, specific, and generic characters. That minute, fortuitous, and indefinite variations could have brought about such special forms and modifications as have been enumerated in this chapter, seems to contradict not imagination, but reason. [Page 62] That either many individuals amongst a species of butterfly should be simultaneously preserved through a similar accidental and minute variation in one definite direction, when variations in many other directions would also preserve; or that one or two so varying should succeed in supplanting the progeny of thousands of other individuals, and that this should by no other cause be carried so far as to produce the appearance (as we have before stated) of spots of fungi, &c.--are alternatives of an improbability so extreme as to be practically equal to impossibility. In spite of all the resources of a fertile imagination, the Darwinian, pure and simple, is reduced to the assertion of a paradox as great as any he opposes. In the place of a mere assertion of our ignorance as to the way these phenomena have been produced, he brings forward, as their explanation, a cause which it is contended in this work is demonstrably insufficient. Of course in this matter, as elsewhere throughout nature, we have to do with the operation of fixed and constant natural laws, and the knowledge of these may before long be obtained by human patience or human genius; but there is, it is believed, already enough evidence to show that these as yet unknown natural laws or law will never be resolved into the action of "Natural Selection," but will constitute or exemplify a mode and condition of organic action of which the Darwinian theory takes no account whatsoever. [Page 63] * * * * * CHAPTER III. THE CO-EXISTENCE OF CLOSELY SIMILAR STRUCTURES OF DIVERSE ORIGIN. Chances against concordant variations.--Examples of discordant ones.--Concordant variations not unlikely on a non-Darwinian evolutionary hypothesis.--Placental and implacental mammals.--Birds and reptiles.--Independent origins of similar sense organs.--The ear.--The eye.--Other coincidences.--Causes besides Natural Selection produce concordant variations in certain geographical regions.--Causes besides Natural Selection produce concordant variations in certain zoological and botanical groups.--There are homologous parts not genetically related.--Harmony in respect of the organic and inorganic worlds.--Summary and conclusion. The theory of "Natural Selection" supposes that the varied forms and structure of animals and plants have been built up merely by indefinite, fortuitous,[49] minute variations in every part and in all directions--those variations only being preserved which are directly or indirectly useful to the individual possessing them, or necessarily correlated with such useful variations. [Illustration: WINGBONES OF PTERODACTYLE, BAT, AND BIRD. (_Copied, by permission, from Mr. Andrew Murray's "Geographical Distribution of Mammals."_)] On this theory the chances are almost infinitely great against the independent, accidental occurrence and preservation of two similar series of minute variations resulting in the independent development of two closely similar forms. In all cases, no doubt (on this same theory), _some_ adaptation to habit or need would gradually be evolved, but that {64} adaptation would surely be arrived at by different roads. The organic world supplies us with multitudes of examples of similar functional results being attained by the most diverse means. Thus the body is sustained in the air by birds and by bats. In the first case it is so sustained by a limb in which the bones of the hand are excessively reduced, but which is provided with immense outgrowths from the skin--namely, the feathers of the wing. In the second case, however, the body is sustained in the air by a limb in which the bones of the hand are enormously increased in length, and so sustain a great expanse of naked skin, which is the flying membrane of the bat's wing. Certain fishes and certain reptiles can also flit and take very prolonged jumps in the air. The flying-fish, however, takes these by means of a great elongation of the rays of the pectoral fins--parts which cannot be said to be of the same nature as the constituents of the wing of either the bat or the bird. The little lizard, which enjoys the formidable name of "flying-dragon," flits by means of a structure altogether peculiar--namely, by the liberation and great elongation of some of the ribs which support a fold of skin. In the extinct pterodactyles--which were _truly_ flying {65} reptiles--we meet with an approximation to the structure of the bat, but in the pterodactyle we have only one finger elongated in each hand: a striking example of how the very same function may be provided for by a modification similar in principle, yet surely manifesting the independence of its origin. When we go to lower animals, we find flight produced by organs, as the wings of insects, which are not even modified limbs at all; or we find even the function sometimes subserved by quite artificial means, as in the aërial spiders, which use their own threads to float with in the air. In the vegetable kingdom the atmosphere is often made use of for the scattering of seeds, by their being furnished with special structures of very different kinds. The diverse modes by which such seeds are dispersed are well expressed by Mr. Darwin. He says:[50] "Seeds are disseminated {66} by their minuteness,--by their capsule being converted into a light balloon-like envelope,--by being embedded in pulp or flesh, formed of the most diverse parts, and rendered nutritious, as well as conspicuously coloured, so as to attract and be devoured by birds,--by having hooks and grapnels of many kinds and serrated awns, so as to adhere to the fur of quadrupeds,--and by being furnished with wings and plumes, as different in shape as elegant in structure, so as to be wafted by every breeze." [Illustration: SKELETON OF THE FLYING-DRAGON. (Showing the elongated ribs which support the flitting organ.)] Again, if we consider the poisoning apparatus possessed by different animals, we find in serpents a perforated--or rather very deeply channelled--tooth. In wasps and bees the sting is formed of modified parts, accessory in reproduction. In the scorpion, we have the median terminal process of the body specially organized. In the spider, we have a specially constructed antenna; and finally in the centipede a pair of modified thoracic limbs. [Illustration: A CENTIPEDE.] It would be easy to produce a multitude of such instances of similar ends being attained by dissimilar means, and it is here contended that by "the action of Natural Selection" _only_ it is so improbable as to be practically impossible for two exactly similar structures to have ever been independently developed. It is so because the number of possible {67} variations is indefinitely great, and it is therefore an indefinitely great number to one against a similar series of variations occurring and being similarly preserved in any two independent instances. The difficulty here asserted applies, however, only to pure Darwinism, which makes use _only_ of indirect modifications through the survival of the fittest. Other theories (for example, that of Mr. Herbert Spencer) admit the _direct_ action of conditions upon animals and plants--in ways not yet fully understood--there being conceived to be at the same time a certain peculiar but limited power of response and adaptation in each animal and plant so acted on. Such theories have not to contend against the difficulty proposed, and it is here urged that even very complex extremely similar structures have again and again been developed quite independently one of the other, and this because the process has taken place not by merely haphazard, indefinite variations in all directions, but by the concurrence of some other and internal natural law or laws co-operating with external influences and with Natural Selection in the evolution of organic forms. It must never be forgotten that to admit any such constant operation of any such unknown natural cause is to deny the purely Darwinian theory, which relies upon the survival of the fittest by means of minute fortuitous indefinite variations. Amongst many other obligations which the Author has to acknowledge to Professor Huxley, are the pointing out of this very difficulty, and the calling his attention to the striking resemblance between certain teeth of the dog and of the thylacine as one instance, and certain ornithic peculiarities of pterodactyles as another. Mammals[51] are divisible into one great group, which comprises the {68} immense majority of kinds termed, from their mode of reproduction, _placental Mammals_, and into another very much smaller group comprising the pouched-beasts or marsupials (which are the kangaroos, bandicoots, phalangers, &c., of Australia), and the true opossums of America, called _implacental Mammals_. Now the placental mammals are subdivided into various orders, amongst which are the flesh-eaters (Carnivora, _i.e._ cats, dogs, otters, weasels, &c.), and the insect-eaters (Insectivora, _i.e._ moles, hedgehogs, shrew-mice, &c.). The marsupial mammals also present a variety of forms (some of which are carnivorous beasts, whilst others are insectivorous), so marked that it has been even proposed to divide them into orders parallel to the orders of placental beasts. The resemblance, indeed, is so striking as, on Darwinian principles, to suggest the probability of genetic affinity; and it even led Professor Huxley, in his Hunterian Lectures, in 1866, to promulgate the notion that a vast and widely-diffused marsupial fauna may have existed anteriorly to the development of the ordinary placental, non-pouched beasts, and that the carnivorous, insectivorous, and herbivorous placentals may have respectively descended from the carnivorous, insectivorous, and herbivorous marsupials. [Illustration: TEETH OF UROTRICHUS AND PERAMELES.] Amongst other points Professor Huxley called attention to the resemblance between the anterior molars of the placental dog with those of the marsupial thylacine. These, indeed, are strikingly similar, but there are better examples still of this sort of coincidence. Thus it has often {69} been remarked that the insectivorous marsupials, _e.g. Perameles_, wonderfully correspond, as to the form of certain of the grinding teeth, with certain insectivorous placentals, _e.g. Urotrichus_. Again, the saltatory insectivores of Africa (_Macroscelides_) not only resemble the kangaroo family (_Macropodidæ_) in their jumping habits and long hind legs, but also in the structure of their molar teeth, and even further, as I have elsewhere[52] pointed out, in a certain similarity of the upper cutting teeth, or incisors. Now these correspondences are the more striking when we bear in mind that a similar dentition is often put to very different uses. The food of different kinds of apes is very different, yet how uniform is their dental structure! Again, who, looking at the teeth of different kinds of bears, would ever suspect that one kind was frugivorous, and another a devourer exclusively of animal food? The suggestion made by Professor Huxley was therefore one which had much to recommend it to Darwinians, though it has not met with any notable acceptance, and though he seems himself to have returned to the older notion, namely, that the pouched-beasts, or marsupials, are a special ancient offshoot from the great mammalian class. But whichever view may be the correct one, we have in either case a number of forms similarly modified in harmony with surrounding conditions, and eloquently proclaiming some natural plastic power, other than mere fortuitous variation with survival of the fittest. If, however, the Reader thinks that teeth are parts peculiarly qualified for rapid variation (in which view the Author cannot concur), he is requested to suspend his judgment till he has considered the question of the independent evolution of the _highest organs of sense_. If this seems to establish the {70} existence of some other law than that of "Natural Selection," then the operation of that other law may surely be also traced in the harmonious co-ordinations of dental form. The other difficulty, kindly suggested to me by the learned Professor, refers to the structure of birds, and of extinct reptiles more or less related to them. The class of birds is one which is remarkably uniform in its organization. So much is this the case, that the best mode of subdividing the class is a problem of the greatest difficulty. Existing birds, however, present forms which, though closely resembling in the greater part of their structure, yet differ importantly the one from the other. One form is exemplified by the ostrich, rhea, emeu, cassowary, apteryx, dinornis, &c. These are the _struthious_ birds. All other existing birds belong to the second division, and are called (from the keel on the breast-bone) _carinate_ birds. Now birds and reptiles have such and so many points in common, that Darwinians must regard the former as modified descendants of ancient reptilian forms. But on Darwinian principles it is impossible that the class of birds so uniform and homogeneous should have had a double reptilian origin. If one set of birds sprang from one set of reptiles, and another set of birds from another set of reptiles, the two sets could never, by "Natural Selection" only, have grown into such a perfect similarity. To admit such a phenomenon would be equivalent to abandoning the theory of "Natural Selection" as the sole origin of species. Now, until recently it has generally been supposed by evolutionists that those ancient flying reptiles, the pterodactyles, or forms allied to them, were the progenitors of the class of birds; and certain parts of their structure especially support this view. Allusion is here made to the bladebone (scapula), and the bone which passes down from the shoulder-joint to the breast-bone (viz. the coracoid). These bones are such remarkable anticipations of the same parts in ordinary (_i.e._ carinate) birds {71} that it is hardly possible for a Darwinian not to regard the resemblance as due to community of origin. This resemblance was carefully pointed out by Professor Huxley in his "Hunterian Course" for 1867, when attention was called to the existence in _Dimorphodon macronyx_ of even that small process which in birds gives attachment to the upper end of the merrythought. Also Mr. Seeley[53] has shown that in pterodactyles, as in birds, the optic lobes of the brain were placed low down on each side--"lateral and depressed." Nevertheless, the view has been put forward and ably maintained by the same Professor,[54] as also by Professor Cope in the United States, that the line of descent from reptiles to birds has not been from ordinary reptiles, through pterodactyle-like forms, to ordinary birds, but to the struthious ones from certain extinct reptiles termed Dinosauria; one of the most familiarly known of which is the Iguanodon of the Wealden formation. In these Dinosauria we find skeletal characters unlike those of ordinary (_i.e._ carinate) birds, but closely resembling in certain points the osseous structure of the struthious birds. Thus a difficulty presents itself as to the explanation of the three following relationships:--(1) That of the Pterodactyles with carinate birds; (2) that of the Dinosauria with struthious birds; (3) that of the carinate and struthious birds with each other. Either birds must have had two distinct origins whence they grew to their present conformity, or the very same skeletal, and probably cerebral characters must have spontaneously and independently arisen. Here is a dilemma, either horn of which bears a threatening aspect to the exclusive supporter of "Natural Selection," and between which it seems somewhat {72} difficult to choose. It has been suggested to me that this difficulty may be evaded by considering pterodactyles and carinate birds as independent branches from one side of an ancient common trunk, while similarly the Dinosauria and struthious birds are taken to be independent branches from the other side of the same common trunk; the two kinds of birds resembling each other so much on account of their later development from that trunk as compared with the development of the reptilian forms. But to this it may be replied that the ancient common stock could not have had at one and the same time a shoulder structure of _both kinds_. It must have been that of the struthious birds or that of the carinate birds, or something different from both. If it was that of the struthious birds, how did the pterodactyles and carinate birds independently arrive at the very same divergent structure? If it was that of the carinate birds, how did the struthious birds and Dinosauria independently agree to differ? Finally, if it was something different from either, how did the carinate birds and pterodactyles take on independently one special common structure when disagreeing in so many; while the struthious birds, agreeing in many points with the Dinosauria, agree yet more with the carinate birds? Indeed by no arrangement of branches from a stem can the difficulty be evaded. Professor Huxley seems inclined[55] to cut the Gordian knot by considering the shoulder structure of the pterodactyle as independently educed, and having relation to physiology only. This conception is one which harmonizes completely with the views here advocated, and with those of Mr. Herbert Spencer, who also calls in direct modification to the aid of "Natural Selection." That merely minute, indefinite variations in all directions should unaided have independently built up the shoulder structure of {73} the pterodactyles and carinate birds, and have laterally depressed their optic lobes, at a time so far back as the deposition of the Oolite strata,[56] is a coincidence of the highest improbability; but that an innate power and evolutionary law, aided by the corrective action of "Natural Selection," should have furnished like needs with like aids, is not at all improbable. The difficulty does not tell against the theory of evolution, but only against the specially Darwinian form of it. Now this form has never been expressly adopted by Professor Huxley; so far from it, in his lecture on this subject at the Royal Institution before referred to, he observes,[57] "I can testify, from personal experience, it is possible to have a complete faith in the general doctrine of evolution, and yet to hesitate in accepting the Nebular, or the Uniformitarian, or the Darwinian hypotheses in all their integrity and fulness." [Illustration: THE ARCHEOPTERYX (of the Oolite strata).] It is quite consistent, then, in the Professor to explain the {74} difficulty as he does; but it would not be similarly so with an absolute and pure Darwinian. Yet stronger arguments of an analogous kind are, however, to be derived from the highest organs of sense. In the most perfectly organized animals--those namely which, like ourselves, possess a spinal column--the internal organs of hearing consist of two more or less complex membranous sacs (containing calcareous particles--otoliths), which are primitively or permanently lodged in two chambers, one on each side of the cartilaginous skull. The primitive cartilaginous cranium supports and protects the base of the brain, and the auditory nerves pass from that brain into the cartilaginous chambers to reach the auditory sacs. These complex arrangements of parts could not have been evolved by "Natural Selection," _i.e._ by minute accidental variations, except by the action of such through a vast period of time; nevertheless, it was fully evolved at the time of the deposition of the upper Silurian rocks. Cuttle-fishes (_Cephalopoda_) are animals belonging to the molluscous primary division of the animal kingdom, which division contains animals formed upon a type of structure utterly remote from that on which the animals of the higher division provided with a spinal column are constructed. And indeed no transitional form (tending even to bridge over the chasm between these two groups) has ever yet been discovered, either living or in a fossilized condition.[58] Nevertheless, in the two-gilled Cephalopods (_Dibranchiata_) we find the brain supported and protected by a cartilaginous cranium. In the base of this cranium are two cartilaginous chambers. In each chamber is a membranous sac containing an otolith, and the auditory nerves pass from the cerebral ganglia into the cartilaginous chambers to reach the auditory sacs. Moreover, it has been suggested by Professor Owen that {75} sinuosities between processes projecting from the inner wall of each chamber "seem to be the first rudiments of those which, in the higher classes (_i.e._ in animals with a spinal column), are extended in the form of canals and spiral chambers, within the substance of the dense nidus of the labyrinth."[59] [Illustration: CUTTLE-FISH. A. Ventral aspect. B. Dorsal aspect.] Here, then, we have a wonderful coincidence indeed; two highly complex auditory organs, marvellously similar in structure, but which must nevertheless have been developed in entire and complete independence one of the other! It would be difficult to calculate the odds against the independent occurrence and conservation of two such complex series of merely accidental and minute haphazard variations. And it can never be {76} maintained that the sense of hearing could not be efficiently subserved otherwise than by such sacs, in cranial cartilaginous capsules so situated in relation to the brain, &c. Our wonder, moreover, may be increased when we recollect that the two-gilled cephalopods have not yet been found below the lias, where they at once abound; whereas the four-gilled cephalopods are Silurian forms. Moreover, the absence is in this case significant in spite of the imperfection of the geological record, because when we consider how many individuals of various kinds of four-gilled cephalopods have been found, it is fair to infer that at the least a certain small percentage of dibranchs would also have left traces of their presence had they existed. Thus it is probable that some four-gilled form was the progenitor of the dibranch cephalopods. Now the four-gilled kinds (judging from the only existing form, the nautilus) had the auditory organ in a very inferior condition of development to what we find in the dibranch; thus we have not only evidence of the independent high development of the organ in the former, but also evidence pointing towards a certain degree of comparative rapidity in its development. Such being the case with regard to the organ of hearing, we have another yet stronger argument with regard to the organ of sight, as has been well pointed out by Mr. J. J. Murphy.[60] He calls attention to the fact that the eye must have been perfected in at least "three distinct lines of descent," alluding not only to the molluscous division of the animal kingdom, and the division provided with a spinal column, but also to a third primary division, namely, that which includes all insects, spiders, crabs, &c., which are spoken of as Annulosa, and the type of whose structure is as distinct from that of the molluscous type on the one hand, as it is from that of the type with a spinal column (_i.e._ the vertebrate type) on the other. {77} In the cuttle-fishes we find an eye even more completely constructed on the vertebrate type than is the ear. Sclerotic, retina, choroid, vitreous humour, lens, aqueous humour, all are present. The correspondence is wonderfully complete, and there can hardly be any hesitation in saying that for such an exact, prolonged, and correlated series of similar structures to have been brought about in two independent instances by merely indefinite and minute accidental variations, is an improbability which amounts practically to impossibility. Moreover, we have here again the same imperfection of the four-gilled cephalopod, as compared with the two-gilled, and therefore (if the latter proceeded from the former) a similar indication of a certain comparative rapidity of development. Finally, and this is perhaps one of the most curious circumstances, the process of formation appears to have been, at least in some respects, the same in the eyes of these molluscous animals as in the eyes of vertebrates. For in these latter the cornea is at first perforated, while different degrees of perforation of the same part are presented by different adult cuttle-fishes--large in the calamaries, smaller in the octopods, and reduced to a minute foramen in the true cuttle-fish sepia. Some may be disposed to object that the conditions requisite for effecting vision are so rigid that similar results in all cases must be independently arrived at. But to this objection it may well be replied that Nature herself has demonstrated that there is no such necessity as to the details of the process. For in the higher Annulosa, such as the dragon-fly, we meet with an eye of an unquestionably very high degree of efficiency, but formed on a type of structure only remotely comparable with that of the fish or the cephalopod. The last-named animal might have had an eye as efficient as that of a vertebrate, but formed on a distinct type, instead of being another edition, as it were, of the very same structure. In the beginning of this chapter examples have been given of the very {78} diverse mode in which similar results have in many instances been arrived at; on the other hand, we have in the fish and the cephalopod not only the eye, but at one and the same time the ear also similarly evolved, yet with complete independence. Thus it is here contended that the similar and complex structures of both the highest organs of sense, as developed in the vertebrates on the one hand, and in the mollusks on the other, present us with residuary phenomena for which "Natural Selection" alone is quite incompetent to account. And that these same phenomena must therefore be considered as conclusive evidence for the action of some other natural law or laws conditioning the simultaneous and independent evolution of these harmonious and concordant adaptations. Provided with this evidence, it may be now profitable to enumerate other correspondences, which are not perhaps in themselves inexplicable by Natural Selection, but which are more readily to be explained by the action of the unknown law or laws referred to--which action, as its necessity has been demonstrated in one case, becomes _a priori_ probable in the others. [Illustration: SKELETON OF AN ICHTHYOSAURUS.] Thus the great oceanic Mammalia--the whales--show striking resemblances to those prodigious, extinct, marine reptiles, the Ichthyosauria, and this not only in structures readily referable to similarity of habit, but in such matters as greatly elongated premaxillary bones, together with the concealment of certain bones of the skull by other cranial bones. [Page 79] Again, the aërial mammals, the bats, resemble those flying reptiles of the secondary epoch, the pterodactyles; not only to a certain extent in the breast-bone and mode of supporting the flying membrane, but also in the proportions of different parts of the spinal column and the hinder (pelvic) limbs. Also bivalve shell-fish (_i.e._ creatures of the mussel, cockle, and oyster class, which receive their name from the body being protected by a double shell, one valve of which is placed on each side) have their two shells united by one or two powerful muscles, which pass directly across from one shell to the other, and which are termed "adductor muscles" because by their contraction they bring together the valves and so close the shell. [Illustration: CYTHERIDEA TOROSA. [An ostracod (Crustacean), externally like a bivalve shell-fish (Lamellibranch).] Now there are certain animals which belong to the crab and lobster class (Crustacea)--a class constructed on an utterly different type from that on which the bivalve shell-fish are constructed--which present a very curious approximation to both the form and, in a certain respect, the structure of true bivalves. Allusion is here made to certain small Crustacea--certain phyllopods and ostracods--which have the hard outer coat of their thorax so modified as to look wonderfully like a bivalve shell, although its {80} nature and composition are quite different. But this is by no means all,--not only is there this external resemblance between the thoracic armour of the crustacean and the bivalve shell, but the two sides of the ostracod and phyllopod thorax are connected together also by an adductor muscle! [Illustration: A POLYZOON WITH BIRD'S-HEAD PROCESSES.] {81} The pedicellariæ of the echinus have been already spoken of, and the difficulty as to their origin from minute, fortuitous, indefinite variations has been stated. But structures essentially similar (called avicularia, or "bird's-head processes") are developed from the surface of the compound masses of certain of the highest of the polyp-like animals (viz. the Polyzoa or, as they are sometimes called, the Bryozoa). These compound animals have scattered over the surface of their bodies minute processes, each of which is like the head of a bird, with an upper and lower beak, the whole supported on a slender neck. The beak opens and shuts at intervals, like the jaws of the pedicellariæ of the echinus, and there is altogether, in general principle, a remarkable similarity between the structures. Yet the echinus can have, at the best, none but the most distant genetic relationship with the Polyzoa. We have here again therefore complex and similar organs of diverse and independent origin. [Illustration: BIRD'S-HEAD PROCESSES VERY GREATLY ENLARGED.] In the highest class of animals (the Mammalia) we have almost always a placental mode of reproduction, _i.e._ the blood of the foetus is placed in nutritive relation with the blood of the mother by means of vascular prominences. No trace of such a structure exists in any bird or in any reptile, and yet it crops out again in certain sharks. There indeed it might well be supposed to end, but, marvellous as it seems, it reappears in very lowly creatures; namely, in certain of the ascidians, sometimes called tunicaries or sea-squirts. [Page 82] Now, if we were to concede that the ascidians were the common ancestors[61] of both these sharks and of the higher mammals, we should be little, if any, nearer to an explanation of the phenomenon by means of "Natural Selection," for in the sharks in question the vascular prominences are developed from one foetal structure (the umbilical vesicle), while in the higher mammals they are developed from quite another part, viz. the allantois. [Illustration: Upper Figure--ANTECHINUS MINUTISSIMUS (_implacental_). Lower Figure--MUS DELICATULUS (_placental_).] So great, however, is the number of similar, but apparently independent, structures, that we suffer from a perfect _embarras de richesses_. Thus, for example, we have the convoluted windpipe of the sloth, reminding us{83} of the condition of the windpipe in birds; and in another mammal, allied to the sloth, namely the great ant-eater (Myrmecophaga), we have again an ornithic character in its horny gizzard-like stomach. In man and the highest apes the cæcum has a vermiform appendix, as it has also in the wombat! Also the similar forms presented by the crowns of the teeth in some seals, in certain sharks, and in some extinct Cetacea may be referred to; as also the similarity of the beak in birds, some reptiles, in the tadpole, and cuttle-fishes. As to entire external form, may be adduced the wonderful similarity between a true mouse (_Mus delicatulus_) and a small marsupial, pointed out by Mr. Andrew Murray in his work on the "Geographical Distribution of Mammals," p. 53, and represented in the frontispiece by figures copied from Gould's "Mammals of Australia;" but instances enough for the present purpose have been already quoted. Additional reasons for believing that similarity of structure is produced by other causes than merely by "Natural Selection" are furnished by certain facts of zoological geography, and by a similarity in the mode of variation being sometimes extended to several species of a genus, or even to widely different groups; while the restriction and the limitation of such similarity are often not less remarkable. Thus Mr. Wallace says,[62] as to local influence: "Larger or smaller districts, or even single islands, give a special character to the majority of their Papilionidæ. For instance:--1. The species of the Indian region (Sumatra, Java, and Borneo) are almost invariably smaller than the allied species inhabiting Celebes and the Moluccas. 2. The species of New Guinea and Australia are also, though in a less degree, smaller than the nearest species or varieties of the Moluccas. 3. In the Moluccas themselves the species of Amboyna are the largest. 4. The species of Celebes equal or even surpass in size those of Amboyna. {84} 5. The species and varieties of Celebes possess a striking character in the form of the anterior wings, different from that of the allied species and varieties of all the surrounding islands. 6. Tailed species in India or the Indian region become tailless as they spread eastward through the Archipelago. 7. In Amboyna and Ceram the females of several species are dull-coloured, while in the adjacent islands they are more brilliant." Again:[63] "In Amboyna and Ceram the female of the large and handsome _Ornithoptera Helena_ has the large patch on the hind wings constantly of a pale dull ochre or buff colour; while in the scarcely distinguishable varieties from the adjacent islands, of Bouru and New Guinea, it is of a golden yellow, hardly inferior in brilliancy to its colour in the male sex. The female of _Ornithoptera Priamus_ (inhabiting Amboyna and Ceram exclusively) is of a pale dusky brown tint, while in all the allied species the same sex is nearly black, with contracted white markings. As a third example, the female of _Papilio Ulysses_ has the blue colour obscured by dull and dusky tints, while in the closely allied species from the surrounding islands, the females are of almost as brilliant an azure blue as the males. A parallel case to this is the occurrence, in the small islands of Goram, Matabello, Ké, and Aru, of several distinct species of Euploea and Diadema, having broad bands or patches of white, which do not exist in any of the allied species from the larger islands. These facts seem to indicate some local influence in modifying colour, as unintelligible and almost as remarkable as that which has resulted in the modifications of form previously described." After endeavouring to explain some of the facts in a way to be noticed directly, Mr. Wallace adds:[64] "But even the conjectural explanation now given fails us in the other cases of local modification. Why the species of the Western Islands should be smaller than those further east; why those of Amboyna should exceed in size those of Gilolo and New Guinea; why the {85} tailed species of India should begin to lose that appendage in the islands, and retain no trace of it on the borders of the Pacific; and why, in three separate cases, the females of Amboyna species should be less gaily attired than the corresponding females of the surrounding islands, are questions which we cannot at present attempt to answer. That they depend, however, on some general principle is certain, because analogous facts have been observed in other parts of the world. Mr. Bates informs me that, in three distinct groups, Papilios, which, on the Upper Amazon, and in most other parts of South America, have spotless upper wings, obtain pale or white spots at Pará and on the Lower Amazon, and also that the Æneas group of Papilios never have tails in the equatorial regions and the Amazon valley, but gradually acquire tails in many cases as they range towards the northern or southern tropic. Even in Europe we have somewhat similar facts, for the species and varieties of butterflies peculiar to the Island of Sardinia are generally smaller and more deeply coloured than those of the mainland, and the same has been recently shown to be the case with the common tortoiseshell butterfly in the Isle of Man; while _Papilio Hospiton_, peculiar to the former island, has lost the tail, which is a prominent feature of the closely allied _P. Machaon_. "Facts of a similar nature to those now brought forward would no doubt be found to occur in other groups of insects, were local faunas carefully studied in relation to those of the surrounding countries; and they seem to indicate that climate and other physical causes have, in some cases, a very powerful effect in modifying specific form and colour, and thus directly aid in producing the endless variety of nature." [Illustration: OUTLINES OF WINGS OF BUTTERFLIES OF CELEBES COMPARED WITH THOSE OF ALLIED SPECIES ELSEWHERE. Outer outline, _Papilio gigon_, of Celebes. Inner outline, _P. demolion_, of Singapore and Java.--2. Outer outline, _P. miletus_, of Celebes. Inner outline, _P. sarpedon_, India.--3. Outer outline, _Tachyris zarinda_, Celebes. Inner outline, _T. nero_.] With regard to butterflies of Celebes belonging to different families, they present "a peculiarity of outline which distinguishes them at a glance from those of any other part of the world:"[65] it is that the upper wings {86} are generally more elongated and the anterior margin more curved. Moreover, there is, in most instances, near the base an abrupt bend or elbow, which in some species is very conspicuous. Mr. Wallace endeavours to explain {87} this phenomenon by the supposed presence at some time of special persecutors of the modified forms, supporting the opinion by the remark that small, obscure, very rapidly flying and mimicked kinds have not had the wing modified. Such an enemy occasioning increased powers of flight, or rapidity in turning, he adds, "one would naturally suppose to be an insectivorous bird; but it is a remarkable fact that most of the genera of fly-catchers of Borneo and Java on the one side, and of the Moluccas on the other, are almost entirely absent from Celebes. Their place seems to be supplied by the caterpillar-catchers, of which six or seven species are known from Celebes, and are very numerous in individuals. We have no positive evidence that these birds pursue butterflies on the wing, but it is highly probable that they do so when other food is scarce. Mr. Bates suggested to me that the larger dragon-flies prey upon butterflies, but I did not notice that they were more abundant in Celebes than elsewhere."[66] Now, every opinion or conjecture of Mr. Wallace is worthy of respectful and attentive consideration, but the explanation suggested and before referred to hardly seems a satisfactory one. What the past fauna of Celebes may have been is as yet conjectural. Mr. Wallace tells us that now there is a remarkable _scarcity_ of fly-catchers, and that their place is supplied by birds of which it can only be said that it is "highly probable" that they chase butterflies "when other food is scarce." The quick eye of Mr. Wallace failed to detect them in the act, as also to note any unusual abundance of other insectivorous forms, which therefore, considering Mr. Wallace's zeal and powers of observation, we may conclude do not exist. Moreover, even if there ever has been an abundance of such, it is by no means certain that they would have succeeded in producing the conformation in question, for the effect of this peculiar curvature on flight is by no means clear. We have here, then, a structure hypothetically explained by an uncertain {88} property induced by a cause the presence of which is only conjectural. Surely it is not unreasonable to class this instance with the others before given, in which a common modification of form or colour coexists with a certain geographical distribution quite independently of the destructive agencies of animals. If physical causes connected with locality can abbreviate or annihilate the tails of certain butterflies, why may not similar causes produce an elbow-like prominence on the wings of other butterflies? There are many such instances of simultaneous modification. Mr. Darwin himself[67] quotes Mr. Gould as believing that birds of the same species are more brightly coloured under a clear atmosphere, than when living on islands or near the coast. Mr. Darwin also informs us that Wollaston is convinced that residence near the sea affects the colour of insects; and finally, that Moquin-Tandon gives a list of plants which, when growing near the sea-shore, have their leaves in some degree fleshy, though not so elsewhere. In his work on "Animals and Plants under Domestication,"[68] Mr. Darwin refers to M. Costa as having (in _Bull. de la Soc. Imp. d'Acclimat_. tome viii. p. 351) stated "that young shells taken from the shores of England and placed in the Mediterranean at once altered their manner of growth, and formed prominent diverging rays _like those on the shells of the proper Mediterranean oyster_;" also to Mr. Meehan, as stating (_Proc. Acad. Nat. Sc. of Philadelphia_, Jan. 28, 1862) "that twenty-nine kinds of American trees all differ from their nearest European allies in _a similar manner_, leaves less toothed, buds and seeds smaller, fewer branchlets," &c. These are striking examples indeed! But cases of simultaneous and similar modifications abound on all sides. Even as regards our own species there is a very generally admitted opinion that a new type has been developed in the United States, and this in about a couple of centuries only, and in a vast multitude of individuals of {89} diverse ancestry. The instances here given, however, must suffice, though more could easily be added. [Illustration: THE GREAT SHIELDED GRASSHOPPER.] It may be well now to turn to groups presenting similar variations, not through, but independently of, geographical distribution, and, as far as we know, independently of conditions other than some peculiar nature and tendency (as yet unexplained) common to members of such groups, which nature and tendency seem to induce them to vary in certain definite lines or directions which are different in different groups. Thus with regard to the group of insects, of which the walking leaf is a member, Mr. Wallace observes:[69] "The _whole family_[70] of the Phasmidæ, or spectres, to which this insect belongs, is more or less imitative, and a great number of the species are called 'walking-stick insects,' from their singular {90} resemblance to twigs and branches." [Illustration: THE SIX-SHAFTED BIRD OF PARADISE.] Again, Mr. Wallace[71] tells us of no less than four kinds of orioles, which birds mimic, more or less, four species of a genus of honey-suckers, the weak orioles finding their profit in being mistaken by certain birds of prey for the strong, active, and gregarious honey-suckers. Now, many other birds would be benefited by similar mimicry, which is none the less confined, in this part of the world, to the oriole genus. It is true that the absence of mimicry in other forms may be explained by their possessing some other (as yet unobserved) means of preservation. But it is nevertheless remarkable, not so much that one species should mimic, as that no less than four should do so in different ways and degrees, all these{91} four belonging to _one and the same genus_. [Illustration: THE LONG-TAILED BIRD OF PARADISE.] In other cases, however, there is not even the help of protective action to account for the phenomenon. Thus we have the wonderful birds of Paradise,[72] which agree in developing plumage unequalled in beauty, but a beauty which, as to details, is of different kinds, and produced in different ways in different species. To develop "beauty and singularity of plumage" is a character of the group, but not of any one definite kind, to be explained merely by inheritance. {92} [Illustration] Again, we have the very curious horned flies,[73] which agree indeed in a common peculiarity, but in one singularly different in detail, in different species and not known to have any protecting effect. Amongst plants, also, we meet with the same peculiarity. The great group of Orchids presents a number of species which offer strange and bizarre {93} approximations to different animal forms, and which have often the appearance of cases of mimicry, as it were in an incipient stage. [Illustration: HORNED FLIES.] [Illustration: THE MAGNIFICENT BIRD OF PARADISE.] The number of similar instances which could be brought forward from amongst animals and plants is very great, but the examples given are, it is {94} hoped, amply sufficient to point towards the conclusion which other facts will, it is thought, establish, viz. that there are causes operating (in the evocation of these harmonious diverging resemblances) other than "Natural Selection," or heredity, and other even than merely geographical, climatal, or any simply external conditions. Many cases have been adduced of striking likenesses between different animals, not due to inheritance; but this should be the less surprising, in that the very same individual presents us with likenesses between different parts of its body (_e.g._, between the several joints of the backbone), which are certainly not so explicable. This, however, leads to a rather large subject, which will be spoken of in the eighth chapter of the present work. Here it will be enough to affirm (leaving the proof of the assertion till later) that parts are often homologous which have no direct genetic relationship,--a fact which harmonizes well with the other facts here given, but which "Natural Selection," pure and simple, seems unable to explain. But surely the independent appearance of similar organic forms is what we might expect, _a priori_, from the independent appearance of similar inorganic ones. As Mr. G. H. Lewes well observes,[74] "We do not suppose the carbonates and phosphates found in various parts of the globe--we do not suppose that the families of alkaloids and salts have any nearer kinship than that which consists in the similarity of their elements, and the conditions of their combination. Hence, in organisms, as in salts, morphological identity may be due to a community of causal connexion, rather than community of descent. "Mr. Darwin justly holds it to be incredible that individuals identically the same should have been produced through Natural Selection from parents _specifically distinct_, but he will not deny that identical forms may issue from parents _genetically distinct_, when these parent forms and {95} the conditions of production are identical. To deny this would be to deny the law of causation." Professor Huxley has, however, suggested[75] that such mineral identity may be explained by applying also to minerals a law of descent; that is, by considering such similar forms as the descendants of atoms which inhabited one special part of the primitive nebular cosmos, each considerable space of which may be supposed to have been under the influence of somewhat different conditions. Surely, however, there can be no real parity between the relationship of existing minerals to nebular atoms, and the relationship of existing animals and plants to the earliest organisms. In the first place, the latter have produced others by generative multiplication, which mineral atoms never did. In the second, existing animals and plants spring from the living tissues of preceding animals and plants, while existing minerals spring from the chemical affinity of separate elements. Carbonate of soda is not formed, by a process of reproduction, from other carbonate of soda, but directly by the suitable juxtaposition of carbon, oxygen, and sodium. Instead of approximating animals and minerals in the mode suggested, it may be that they are to be approximated in quite a contrary fashion; namely, by attributing to mineral species an internal innate power. For, as we must attribute to each elementary atom an innate power and tendency to form (under the requisite external conditions) certain unions with other atoms, so we may attribute to certain mineral species--as crystals--an innate power and tendency to exhibit (the proper conditions being supplied) a definite and symmetrical external form. The distinction between animals and vegetables on the one hand, and minerals on the other, is that, while in the organic world close similarity is the result sometimes of inheritance, sometimes of direct production independently of parental action, in the{96} inorganic world the latter is the constant and only mode in which such similarity is produced. When we come to consider the relations of species to space--in other words, the geographical distribution of organisms--it will be necessary to return somewhat to the subject of the independent origin of closely similar forms, in regard to which some additional remarks will be found towards the end of the seventh chapter. In this third chapter an effort has been made to show that while on the Darwinian theory concordant variations are extremely improbable, yet Nature presents us with abundant examples of such; the most striking of which are, perhaps, the higher organs of sense. Also that an important influence is exercised by conditions connected with geographical distribution, but that a deeper-seated influence is at work, which is hinted at by those special tendencies in definite directions, which are the properties of certain groups. Finally, that these facts, when taken together, afford strong evidence that "Natural Selection" has not been the exclusive or predominant cause of the various organic structural peculiarities. This conclusion has also been re-enforced by the consideration of phenomena presented to us by the inorganic world. [Page 97] * * * * * CHAPTER IV. MINUTE AND GRADUAL MODIFICATIONS. There are difficulties as to minute modifications, even if not fortuitous.--Examples of sudden and considerable modifications of different kinds.--Professor Owen's view.--Mr. Wallace.--Professor Huxley.--Objections to sudden changes.--Labyrinthodont.--Potto.--Cetacea.--As to origin of bird's wing.--Tendrils of climbing plants.--Animals once supposed to be connecting links.--Early specialization of structure.--Macrauchenia.--Glyptodon.--Sabre-toothed tiger.--Conclusion. Not only are there good reasons against the acceptance of the exclusive operation of "Natural Selection" as the one means of specific origination, but there are difficulties in the way of accounting for such origination by the sole action of modifications which are infinitesimal and minute, whether fortuitous or not. Arguments may yet be advanced in favour of the view that new species have from time to time manifested themselves with suddenness, and by modifications appearing at once (as great in degree as are those which separate _Hipparion_ from _Equus_), the species remaining stable in the intervals of such modifications: by stable being meant that their variations only extend for a certain degree in various directions, like oscillations in a stable equilibrium. This is the conception of Mr. Galton,[76] who compares the development of species with a many {98} facetted spheroid tumbling over from one facet, or stable equilibrium, to another. The existence of internal conditions in animals corresponding with such facets is denied by pure Darwinians, but it is contended in this work, though not in this chapter, that something may also be said for their existence. The considerations brought forward in the last two chapters, namely, the difficulties with regard to incipient and closely similar structures respectively, together with palæontological considerations to be noticed later, appear to point strongly in the direction of sudden and considerable changes. This is notably the case as regards the young oysters already mentioned, which were taken from the shores of England and placed in the Mediterranean, and at once altered their mode of growth and formed prominent diverging rays, _like those of the proper Mediterranean oyster_; as also the twenty-nine kinds of American trees, all differing from their nearest European allies _similarly_--"leaves less toothed, buds and seeds smaller, fewer branchlets," &c. To these may be added other facts given by Mr. Darwin. Thus he says, "that climate, to a certain extent, directly modifies the form of dogs."[77] The Rev. R. Everett found that setters at Delhi, though most carefully paired, yet had young with "nostrils more contracted, noses more pointed, size inferior, and limbs more slender." Again, cats at Mombas, on the coast of Africa, have short stiff hairs instead of fur, and a cat at Algoa Bay, when left only eight weeks at Mombas, "underwent a complete metamorphosis, having parted with its sandy-coloured fur."[78] The conditions of life seem to produce a considerable effect on horses, and instances are given by Mr. Darwin of pony breeds[79] having independently arisen in different parts of the world, possessing a certain similarity in their physical {99} conditions. Also changes due to climate may be brought about at once in a second generation, though no appreciable modification is shown by the first. Thus "Sir Charles Lyell mentions that some Englishmen, engaged in conducting the operations of the Real del Monte Company in Mexico, carried out with them some greyhounds of the best breed to hunt the hares which abound in that country. It was found that the greyhounds could not support the fatigues of a long chase in this attenuated atmosphere, and before they could come up with their prey they lay down gasping for breath; but these same animals have produced whelps, which have grown up, and are not in the least degree incommoded by the want of density in the air, but run down the hares with as much ease as do the fleetest of their race in this country."[80] We have here no action of "Natural Selection;" it was not that certain puppies happened accidentally to be capable of enduring more rarefied air, and so survived, but the offspring were directly modified by the action of surrounding conditions. Neither was the change elaborated by minute modifications in many successive generations, but appeared at once in the second. With regard once more to sudden alterations of form, Nathusius is said to state positively as to pigs,[81] that the result of common experience and of his experiments was that rich and abundant food, given during youth, tends by some direct action to make the head broader and shorter. Curious jaw appendages often characterize Normandy pigs, according to M. Eudes Deslongchamps. Richardson figures these appendages on the old "Irish greyhound pig," and they are said by Nathusius to appear occasionally in all the long-eared races. Mr. Darwin observes,[82] "As no wild pigs are known to have analogous appendages, we have at present no reason to {100} suppose that their appearance is due to reversion; and if this be so, we are forced to admit that somewhat complex, though apparently useless structures may be suddenly developed without the aid of selection." Again, "Climate directly affects the thickness of the skin and hair" of cattle.[83] In the English climate an individual Porto Santo rabbit[84] recovered the proper colour of its fur in rather less than four years. The effect of the climate of India on the turkey is considerable. Mr. Blyth[85] describes it as being much degenerated in size, "utterly incapable of rising on the wing," of a black colour, and "with long pendulous appendages over the beak enormously developed." Mr. Darwin again tells us that there has suddenly appeared in a bed of common broccoli a peculiar variety, faithfully transmitting its newly acquired and remarkable characters;[86] also that there have been a rapid transformation and transplantation of American varieties of maize with a European variety;[87] that certainly "the Ancon and Manchamp breeds of sheep," and that (all but certainly) Niata cattle, turnspit and pug dogs, jumper and frizzled fowls, short-faced tumbler pigeons, hook-billed ducks, &c., and a multitude of vegetable varieties, have suddenly appeared in nearly the same state as we now see them.[88] Lastly, Mr. Darwin tells us, that there has been an occasional development (in five distinct cases) in England of the "japanned" or "black-shouldered peacock" (_Pavo nigripennis_), a distinct species, according to Dr. Sclater,[89] yet arising in Sir J. Trevelyan's flock composed entirely of the common kind, and increasing, "_to the extinction of the previously existing breed_."[90] Mr. Darwin's only explanation of the phenomena (on the supposition of the species being distinct) is by{101} reversion, owing to a supposed ancestral cross. But he candidly admits, "I have heard of no other such case in the animal or vegetable kingdom." On the supposition of its being only a variety, he observes, "The case is the most remarkable ever recorded of the abrupt appearance of a new form, which so closely resembles a true species, that it has deceived one of the most experienced of living ornithologists." As to plants, M. C. Naudin[91] has given the following instances of the sudden origination of apparently permanent forms. "The first case mentioned is that of a poppy, which took on a remarkable variation in its fruit--a crown of secondary capsules being added to the normal central capsule. A field of such poppies was grown, and M. Göppert, with seed from this field, obtained still this monstrous form in great quantity. Deformities of ferns are sometimes sought after by fern-growers. They are now always obtained by taking spores from the abnormal parts of the monstrous fern; from which spores ferns presenting the same peculiarities invariably grow.... The most remarkable case is that observed by Dr. Godron, of Nancy. In 1861 that botanist observed, amongst a sowing of _Datura tatula_, the fruits of which are very spinous, a single individual of which the capsule was perfectly smooth. The seeds taken from this plant all furnished plants having the character of this individual. The fifth and sixth generations are now growing without exhibiting the least tendency to revert to the spinous form. More remarkable still, when crossed with the normal _Datura tatula_, hybrids were produced, which, in the second generation, reverted to the original types, as true hybrids do." There are, then, abundant instances to prove that considerable {102} modifications may suddenly develop themselves, either due to external conditions or to obscure internal causes in the organisms which exhibit them. Moreover, these modifications, from whatever cause arising, are capable of reproduction--the modified individuals "breeding true." The question is whether new species have been developed by non-fortuitous variations which are insignificant and minute, or whether such variations have been comparatively sudden, and of appreciable size and importance? Either hypothesis will suit the views here maintained equally well (those views being opposed only to fortuitous, indefinite variations), but the latter is the more remote from the Darwinian conception, and yet has much to be said in its favour. Professor Owen considers, with regard to specific origination, that natural history "teaches that the change would be sudden and considerable: it opposes the idea that species are transmitted by minute and slow degrees."[92] "An innate tendency to deviate from parental type, operating through periods of adequate duration," being "the most probable nature, or way of operation of the secondary law, whereby species have been derived one from the other."[93] Now, considering the number of instances adduced of sudden modifications in domestic animals, it is somewhat startling to meet with Mr. Darwin's dogmatic assertion that it is "a _false belief_" that natural species have often originated in the same abrupt manner. The belief _may_ be false, but it is difficult to see how its falsehood can be positively asserted. It is demonstrated by Mr. Darwin's careful weighings and measurements, that, though little used parts in domestic animals get reduced in weight and somewhat in size, yet that they show no inclination to become truly "rudimentary structures." Accordingly he asserts[94] that such {103} rudimentary parts are formed "suddenly, by arrest of development" in domesticated animals, but in wild animals slowly. The latter assertion, however, is a _mere assertion_; necessary, perhaps, for the theory of "Natural Selection," but as yet unproved by facts. But why should not these changes take place suddenly in a state of nature? As Mr. Murphy says,[95] "It may be true that we have no evidence of the origin of wild species in this way. But this is not a case in which negative evidence proves anything. We have never witnessed the origin of a wild species by any process whatever; and if a species were to come suddenly into being in the wild state, as the Ancon Sheep did under domestication, how could you ascertain the fact? If the first of a newly-begotten species were found, the fact of its discovery would tell nothing about its origin. Naturalists would register it as a very rare species, having been only once met with, but they would have no means of knowing whether it were the first or the last of its race." To this Mr. Wallace has replied (in his review of Mr. Murphy's work in _Nature_[96]), by objecting that sudden changes could very rarely be useful, because each kind of animal is a nicely balanced and adjusted whole, any one sudden modification of which would in most cases be hurtful unless accompanied by other simultaneous and harmonious modifications. If, however, it is not unlikely that there is an innate tendency to deviate at certain times, and under certain conditions, it is no more unlikely that that innate tendency should be an harmonious one, calculated to simultaneously adjust the various parts of the organism to their new relations. The objection as to the sudden abortion of rudimentary organs may be similarly met. Professor Huxley seems now disposed to accept the, at least {104} occasional, intervention of sudden and considerable variations. In his review of Professor Kölliker's[97] criticisms, he himself says,[98] "We greatly suspect that she" (_i.e._ Nature) "does make considerable jumps in the way of variation now and then, and that these saltations give rise to some of the gaps which appear to exist in the series of known forms." [Illustration: MUCH ENLARGED HORIZONTAL SECTION OF THE TOOTH OF A LABYRINTHODON.] In addition to the instances brought forward in the second chapter against the minute action of Natural Selection, may be mentioned such {105} structures as the wonderfully folded teeth of the labyrinthodonts. The marvellously complex structure of these organs is not merely unaccountable as due to Natural "Selection," but its production by insignificant increments of complexity is hardly less difficult to comprehend. Similarly the aborted index of the Potto (_Perodicticus_) is a structure not likely to have been induced by minute changes; while, as to "Natural Selection," the reduction of the fore-finger to a mere rudiment is inexplicable indeed! "How this mutilation can have aided in the struggle for life, we must confess, baffles our conjectures on the subject; for that any very appreciable gain to the individual can have resulted from the slightly lessened degree of required nourishment thence resulting (_i.e._ from the suppression), seems to us to be an almost absurd proposition."[99] [Illustration: HAND OF THE POTTO (PERODICTICUS), FROM LIFE.] Again, to anticipate somewhat, the great group of whales (Cetacea) was fully developed at the deposition of the Eocene strata. On the other hand, we may pretty safely conclude that these animals were absent as late as the latest secondary rocks, so that their development could not have been so very slow, unless geological time is (although we shall presently see there are grounds to believe it is not) practically infinite. It is quite true that it is, in general, very unsafe to infer the absence of any animal forms during a certain geological period, because no remains of them {106} have as yet been found in the strata then deposited: but in the case of the Cetacea it is safe to do so; for, as Sir Charles Lyell remarks,[100] they are animals, the remains of which are singularly likely to have been preserved had they existed, in the same way that the remains were preserved of the Ichthyosauri and Plesiosauri, which appear to have represented the Cetacea during the secondary geological period. [Illustration: SKELETON OF A PLESIOSAURUS.] As another example, let us take the origin of wings, such as exist in birds. Here we find an arm, the bones of the hand of which are atrophied and reduced in number, as compared with those of most other Vertebrates. Now, if the wing arose from a terrestrial or subaërial organ, this abortion of the bones could hardly have been serviceable--hardly have preserved individuals in the struggle for life. If it arose from an aquatic organ, like the wing of the penguin, we have then a singular divergence from the ordinary vertebrate fin-limb. In the ichthyosaurus, in the plesiosaurus, in the whales, in the porpoises, in the seals, and in others, we have shortening of the bones, but no reduction in the number either of the fingers or of their joints, which are, on the contrary, multiplied in Cetacea and the ichthyosaurus. And even in the turtles we have eight carpal bones and five digits, while no finger has less than two phalanges. It{107} is difficult, then, to believe that the Avian limb was developed in any other way than by a comparatively sudden modification of a marked and important kind. [Illustration: SKELETON OF AN ICHTHYOSAURUS.] How, once more, can we conceive the peculiar actions of the tendrils of some climbing plants to have been produced by minute modifications? These, according to Mr. Darwin,[101] oscillate till they touch an object, and then embrace it. It is stated by that observer, "that a thread weighing no more than the thirty-second of a grain, if placed on the tendril of the _Passiflora gracilis_, will cause it to bend; and merely to touch the tendril with a twig causes it to bend; but if the twig is at once removed, the tendril soon straightens itself. But the contact of other tendrils of the plant, or of the falling of drops of rain, do not produce these effects."[102] But some of the zoological and anatomical discoveries of late years tend rather to diminish than to augment the evidence in favour of minute and gradual modification. Thus all naturalists now admit that certain animals, which were at one time supposed to be connecting links between groups, belong altogether to one group, and not at all to the other. For example, the aye-aye[103] (_Chiromys Madagascariensis_). {108} was till lately considered to be allied to the squirrels, and was often classed with them in the rodent order, principally on account of its dentition; at the same time that its affinities to the lemurs and apes were admitted. The thorough investigation into its anatomy that has now been made, demonstrates that it has no more essential affinity to rodents than any other lemurine creature has. [Illustration: THE AYE-AYE.] Bats were, by the earliest observers, naturally supposed to have a close relationship to birds, and cetaceans to fishes. It is almost superfluous to observe that all now agree that these mammals make not even an approach to either one or other of the two inferior classes. {109} In the same way it has been recently supposed that those extinct flying saurians, the pterodactyles, had an affinity with birds more marked than any other known animals. Now, however, as has been said earlier, it is contended that not only had they no such close affinity, but that other extinct reptiles had a far closer one. The _amphibia_ (_i.e._ frogs, toads, and efts) were long considered (and are so still by some) to be reptiles, showing an affinity to fishes. It now appears that they form with the latter one great group--the ichthyopsida of Professor Huxley--which differs widely from reptiles; while its two component classes (fishes and amphibians) are difficult to separate from each other in a thoroughly satisfactory manner. If we admit the hypothesis of gradual and minute modification, the succession of organisms on this planet must have been a progress from the more general to the more special, and no doubt this has been the case in the majority of instances. Yet it cannot be denied that some of the most recently formed fossils show a structure singularly more generalized than any exhibited by older forms; while others are more specialized than are any allied creatures of the existing creation. A notable example of the former circumstance is offered by macrauchenia--a hoofed animal, which was at first supposed to be a kind of great llama (whence its name)--the llama being a ruminant, which, like all the rest, has two toes to each foot. Now hoofed animals are divisible into two very distinct series, according as the number of functional toes on each hind foot is odd or even. And many other characters are found to go with this obvious one. Even the very earliest Ungulata show this distinction, which is completely developed and marked even in the Eocene palæotherium and anoplotherium found in Paris by Cuvier. The former of these has the toes odd (perissodactyle), the other has them even (artiodactyle). Now, the macrauchenia, from the first relics of it which were found, {110} was thought to belong, as has been said, to the even-toed division. Subsequent discoveries, however, seemed to give it an equal claim to rank amongst the perissodactyle forms. Others again inclined the balance of probability towards the artiodactyle. Finally, it appears that this very recently extinct beast presents a highly generalized type of structure, uniting in one organic form both artiodactyle and perissodactyle characters, and that in a manner not similarly found in any other known creature living, or fossil. At the same time the differentiation of artiodactyle and perissodactyle forms existed as long ago as in the period of the Eocene ungulata, and that in a marked degree, as has been before observed. Again, no armadillo _now living_ presents nearly so remarkable a speciality of structure as was possessed by the _extinct_ glyptodon. In that singular animal the spinal column had most of its joints fused together, forming a rigid cylindrical rod, a modification, as far as yet known, absolutely peculiar to it. [Illustration: DENTITION OF THE SABRE-TOOTHED TIGER (MACHAIRODUS).] In a similar way the _extinct_ machairodus, or sabre-toothed tiger, is characterized by a more highly differentiated and specially carnivorous dentition than is shown by any predacious beast of the _present day_. {111} The specialization is of this kind. The grinding teeth (or molars) of beasts are divided into premolars and true molars. The premolars are molars which have deciduous vertical predecessors (or milk teeth), and any which are in front of such, _i.e._ between such and the canine tooth. The true molars are those placed behind the molars having deciduous vertical predecessors. Now, as a dentition becomes more distinctly carnivorous, so the hindmost molars and the foremost premolars disappear. In the existing cats this process is carried so far that in the upper jaw only one true molar is left on each side. In the machairodus there is no upper true molar at all, while the premolars are reduced to two, there being only these two teeth above, on each side, behind the canine. Now, with regard to these instances of early specialization, as also with regard to the changed estimate of the degrees of affinity between forms, it is not pretended for a moment that such facts are irreconcilable with "Natural Selection." Nevertheless, they point in an opposite direction. Of course not only is it conceivable that certain antique types arrived at a high degree of specialization and then disappeared; but it is manifest they did do so. Still the fact of this early degree of excessive specialization tells to a certain, however small, extent against a progress through excessively minute steps, whether fortuitous or not; as also does the distinctness of forms formerly supposed to constitute connecting links. For, it must not be forgotten, that if species have manifested themselves generally by gradual and minute modifications, then the absence, not in one but in _all cases_, of such connecting links, is a phenomenon which remains to be accounted for. It appears then that, apart from fortuitous changes, there are certain difficulties in the way of accepting extremely minute modifications of any kind, although these difficulties may not be insuperable. Something, at all events, is to be said in favour of the opinion that sudden and {112} appreciable changes have from time to time occurred, however they may have been induced. Marked _races_ have undoubtedly so arisen (some striking instances having been here recorded), and it is at least conceivable that such may be the mode of _specific_ manifestation generally, the possible conditions as to which will be considered in a later chapter. [Page 113] * * * * * CHAPTER V. AS TO SPECIFIC STABILITY. What is meant by the phrase "specific stability;" such stability to be expected _a priori_, or else considerable changes at once.--Rapidly increasing difficulty of intensifying race characters; alleged causes of this phenomenon; probably an internal cause co-operates.--A certain definiteness in variations.--Mr. Darwin admits the principle of specific stability in certain cases of unequal variability.--The goose.--The peacock.--The guinea fowl.--Exceptional causes of variation under domestication.--Alleged tendency to reversion.--Instances.--Sterility of hybrids.--Prepotency of pollen of same species, but of different race.--Mortality in young gallinaceous hybrids.--A bar to intermixture exists somewhere.--Guinea-pigs.--Summary and conclusion. As was observed in the preceding chapters, arguments may yet be advanced in favour of the opinion that species are stable (at least in the intervals of their comparatively sudden successive manifestations); that the organic world consists, according to Mr. Galton's before-mentioned conception, of many facetted spheroids, each of which can repose upon any one facet, but, when too much disturbed, rolls over till it finds repose in stable equilibrium upon another and distinct facet. Something, it is here contended, may be urged, in favour of the existence of such facets--of such intermitting conditions of stable equilibrium. A view as to the stability of species, in the intervals of change, has been well expressed in an able article, before quoted from, as follows:[104]--"A given animal or plant appears to be contained, as it were, within a {114} sphere of variation: one individual lies near one portion of the surface; another individual, of the same species, near another part of the surface; the average animal at the centre. Any individual may produce descendants varying in any direction, but is more likely to produce descendants varying towards the centre of the sphere, and the variations in that direction will be greater in amount than the variations towards the surface." This might be taken as the representation of the normal condition of species (_i.e._ during the periods of repose of the several facets of the spheroids), on that view which, as before said, may yet be defended. Judging the organic world from the inorganic, we might expect, _a priori_, that each species of the former, like crystallized species, would have an approximate limit of form, and even of size, and at the same time that the organic, like the inorganic forms, would present modifications in correspondence with surrounding conditions; but that these modifications would be, not minute and insignificant, but definite and appreciable, equivalent to the shifting of the spheroid on to another facet for support. Mr. Murphy says,[105] "Crystalline formation is also dependent in a very remarkable way on the medium in which it takes place." "Beudant has found that common salt crystallizing from pure water forms cubes, but if the water contains a little boracic acid, the angles of the cubes are truncated. And the Rev. E. Craig has found that carbonate of copper, crystallizing from a solution containing sulphuric acid, forms hexagonal tubular prisms; but if a little ammonia is added, the form changes to that of a long rectangular prism, with secondary planes in the angles. If a little more ammonia is added, several varieties of rhombic octahedra appear; if a little nitric acid is added, the rectangular prism appears again. The changes take place not by the addition of new crystals, but by changing the growth of the original ones." These, however, may be said{115} to be the same species, after all; but recent researches by Dr. H. Charlton-Bastian seem to show that modifications in the conditions may result in the evolution of forms so diverse as to constitute different organic species. Mr. Murphy observes[106] that "it is scarcely possible to doubt that the various forms of fungi which are characteristic of particular situations are not really distinct species, but that the same germ will develop into different forms, according to the soil on which it falls;" but it is possible to interpret the facts differently, and it may be that these are the manifestations of really different and distinct species, developed according to the different and distinct circumstances in which each is placed. Mr. Murphy quotes Dr. Carpenter[107] to the effect that "No _Puccinia_ but the _Puccinia rosæ_ is found upon rose bushes, and this is seen nowhere else; _Omygena exigua_ is said to be never seen but on the hoof of a dead horse; and _Isaria felina_ has only been observed upon the dung of cats, deposited in humid and obscure situations." He adds, "We can scarcely believe that the air is full of the germs of distinct species of fungi, of which one never vegetates until it falls on the hoof of a dead horse, and another till it falls on cat's dung in a damp and dark place." This is true, but it does not quite follow that they are necessarily the same species if, as Dr. Bastian seems to show, thoroughly different and distinct organic forms[108] can be evolved one from another by modifying the conditions. This observer has brought forward arguments and facts from which it would appear that such definite, sudden, and considerable transformations may take place in the lowest organisms. If such is really the case, we might expect, _a priori_, to find in the highest organisms a tendency (much more impeded and rare in its manifestations) to {116} similarly appreciable and sudden changes, under certain stimuli; but a tendency to continued stability, under normal and ordinary conditions. The proposition that species have, under ordinary circumstances, a definite limit to their variability, is largely supported by facts brought forward by the zealous industry of Mr. Darwin himself. It is unquestionable that the degrees of variation which have been arrived at in domestic animals have been obtained more or less readily in a moderate amount of time, but that further development in certain desired directions is in some a matter of extreme difficulty, and in others appears to be all but, if not quite, an impossibility. It is also unquestionable that the degree of divergence which has been attained in one domestic species is no criterion of the amount of divergence which has been attained in another. It is contended on the other side that we have no evidence of any limits to variation other than those imposed by physical conditions, such, _e.g._, as those which determine the greatest degree of speed possible to any animal (of a given size) moving over the earth's surface; also it is said that the differences in degree of change shown by different domestic animals depend in great measure upon the abundance or scarcity of individuals subjected to man's selection, together with the varying direction and amount of his attention in different cases; finally, it is said that the changes found in nature are within the limits to which the variation of domestic animals extends,--it being the case that when changes of a certain amount have occurred to a species under nature, it becomes _another species_, or sometimes _two or more other species_ by divergent variations, each of these species being able again to vary and diverge in any useful direction. But the fact of the rapidly increasing difficulty found in producing by ever such careful selection, any further extreme in some charge already carried very far (such as the tail of the "fan-tailed pigeon" or the crop of the "pouter"), is certainly, so far as it goes, on the side of the {117} existence of definite limits to variability. It is asserted in reply, that physiological conditions of health and life may bar any such further development. Thus, Mr. Wallace says[109] of these developments: "Variation seems to have reached its limits in these birds. But so it has in nature. The fantail has not only more tail-feathers than any of the three hundred and forty existing species of pigeons, but more than any of the eight thousand known species of birds. There is, of course, some limit to the number of feathers of which a tail useful for flight can consist, and in the fantail we have probably reached that limit. Many birds have the oesophagus or the skin of the neck more or less dilatable, but in no known bird is it so dilatable as in the pouter pigeon. Here again the possible limit, compatible with a healthy existence, has probably been reached. In like manner, the differences in the size and form of the beak in the various breeds of the domestic pigeon, is greater than that between the extreme forms of beak in the various genera and sub-families of the whole pigeon tribe. From these facts, and many others of the same nature, we may fairly infer, that if rigid selection were applied to any organ, we could in a comparatively short time produce a much greater amount of change than that which occurs between species and species in a state of nature, since the differences which we do produce are often comparable with those which exist between distinct genera or distinct families." But in a domestic bird like the fantail where Natural Selection does not come into play, the tail-feathers could hardly be limited by "utility for flight," yet two more tail-feathers could certainly exist in a fancy breed if "utility for flight" were the only obstacle. It seems probable that the real barrier is an _internal_ one in the nature of the organism, and the existence of such is just what is contended for in this chapter. As to{118} the differences between domestic races being greater than those between species or even genera, that is not enough for the argument. For upon the theory of "Natural Selection" all birds have a common origin, from which they diverged by infinitesimal changes, so that we ought to meet with sufficient changes to warrant the belief that a hornbill could be produced from a humming-bird, proportionate time being allowed. But not only does it appear that there are barriers which oppose change in certain directions, but that there are positive tendencies to development along certain special lines. In a bird which has been kept and studied like the pigeon, it is difficult to believe that any remarkable spontaneous variations would pass unnoticed by breeders, or that they would fail to be attended to and developed by some one fancier or other. On the hypothesis of _indefinite_ variability, it is then hard to say why pigeons with bills like toucans, or with certain feathers lengthened like those of trogans, or those of birds of paradise, have never been produced. This, however, is a question which may be settled by experiment. Let a pigeon be bred with a bill like a toucan's, and with the two middle tail-feathers lengthened like those of the king bird of paradise, or even let individuals be produced which exhibit any marked tendency of the kind, and indefinite variability shall be at once conceded. As yet all the changes which have taken place in pigeons are of a few definite kinds only, such as may be well conceived to be compatible with a species possessed of a certain inherent capacity for considerable yet definite variation, a capacity for the ready production of certain degrees of abnormality, which then cannot be further increased. Mr. Darwin himself has already acquiesced in the proposition here maintained, inasmuch as he distinctly affirms the existence of a marked internal barrier to change in certain cases. And if this is admitted in one case, the _principle_ is conceded, and it immediately becomes probable that such internal barriers exist in all, although enclosing a much larger {119} field for variation in some cases than in others. Mr. Darwin abundantly demonstrates the variability of dogs, horses, fowls, and pigeons, but he none the less shows clearly the _very small_ extent to which the goose, the peacock, and the guinea-fowl have varied.[110] Mr. Darwin attempts to explain this fact as regards the goose by the animal being valued only for food and feathers, and from no pleasure having been felt in it on other accounts. He adds, however, at the end the striking remark,[111] which concedes the whole position, "but the goose seems to have _a singularly inflexible organization_." This is not the only place in which such expressions are used. He elsewhere makes use of phrases which quite harmonize with the conception of a normal specific constancy, but varying greatly and suddenly at intervals. Thus he speaks[112] of a _whole organization seeming to have become plastic, and tending to depart from the parental type_. That different organisms should have different degrees of variability, is only what might have been expected _a priori_ from the existence of parallel differences in inorganic species, some of these having but a single form, and others being polymorphic. To return to the goose, however, it may be remarked that it is at least as probable that its fixity of character is the cause of the neglect, as the reverse. It is by no means unfair to assume that _had_ the goose shown a tendency to vary similar in degree to the tendency to variation of the fowl or pigeon, it would have received attention at once on that account. As to the peacock it is excused on the pleas (1), that the individuals maintained are so few in number, and (2) that its beauty is so great it can hardly be improved. But the individuals maintained _have not been too few_ for the independent origin of the black-shouldered form, or for the supplanting of the commoner one by it. As to any neglect in selection,{120} it can hardly be imagined that with regard to this bird (kept as it is all but exclusively for its beauty), any spontaneous beautiful variation in colour or form would have been neglected. On the contrary, it would have been seized upon with avidity and preserved with anxious care. Yet apart from the black-shouldered and white varieties, no tendency to change has been known to show itself. As to its being too beautiful for improvement, that is a proposition which can hardly be maintained. Many consider the Javan bird as much handsomer than the common peacock, and it would be easy to suggest a score of improvements as regards either species. The guinea-fowl is excused, as being "no general favourite, and scarcely more common than the peacock;" but Mr. Darwin himself shows and admits that it is a noteworthy instance of constancy under very varied conditions. These instances alone (and there are yet others) seem sufficient to establish the assertion, that degree of change is different in different domestic animals. It is, then, somewhat unwarrantable in any Darwinian to assume that _all_ wild animals have a capacity for change similar to that existing in _some_ of the domestic ones. It seems more reasonable to assert the opposite, namely, that if, as Mr. Darwin says, the capacity for change is different in different domestic animals, it must surely be limited in those which have it least, and _a fortiori_ limited in wild animals. Indeed, it cannot be reasonably maintained that wild species certainly vary as much as do domestic races; it is possible that they may do so, but at least this has not been yet shown. Indeed, the much greater degree of variation amongst domestic animals than amongst wild ones is asserted over and over again by Mr. Darwin, and his assertions are supported by an overwhelming mass of facts and instances. Of course, it may be asserted that a tendency to indefinite change exists in all cases, and that it is only the circumstances and conditions of {121} life which modify the effects of this tendency to change so as to produce such different results in different cases. But assertion is not proof, and this assertion has not been proved. Indeed, it may be equally asserted (and the statement is more consonant with some of the facts given), that domestication in certain animals induces and occasions a capacity for change which is wanting in wild animals--the introduction of new causes occasioning new effects. For, though a certain degree of variability (normally, in all probability, only oscillation) exists in all organisms, yet domestic ones are exposed to new and different causes of variability, resulting in such striking divergencies as have been observed. Not even in this latter case, however, is it necessary to believe that the variability is indefinite, but only that the small oscillations become in certain instances intensified into large and conspicuous ones. Moreover, it is possible that some of our domestic animals have been in part chosen and domesticated through possessing variability in an eminent degree. That each species exhibits certain oscillations of structure is admitted on all hands. Mr. Darwin asserts that this is the exhibition of a tendency to vary which is absolutely indefinite. If this indefinite variability _does_ exist, of course no more need be said. But we have seen that there are arguments _a priori_ and _a posteriori_ against it, while the occurrence of variations in certain domestic animals greater in degree than the differences between many wild species, is no argument in favour of its existence, until it can be shown that the causes of variability in the one case are the same as in the other. An argument against it, however, may be drawn from the fact, that certain animals, though placed under the influence of those exceptional causes of variation to which domestic animals are subject, have yet never been known to vary, even in a degree equal to that in which certain wild kinds have been ascertained to vary. In addition to this immutability of character in some animals, it is {122} undeniable, that domestic varieties have little stability, and much tendency to reversion, whatever be the true explanation of such phenomena. In controverting the generally received opinion as to "reversion," Mr. Darwin has shown that it is not all breeds which in a few years revert to the original form; but he has shown no more. Thus, the feral rabbits of Porto Santo, Jamaica, and the Falkland Islands, have not yet so reverted in those several localities.[113] Nevertheless, a Porto Santo rabbit brought to England reverted in a manner the most striking, recovering the proper colour of its fur "in rather less than four years."[114] Again, the white silk fowl, in our climate, "reverts to the ordinary colour of the common fowl in its skin and bones, due care having been taken to prevent any cross."[115] This reversion taking place in spite of careful selection, is very remarkable. Numerous other instances of reversion are given by Mr. Darwin, both as regards plants and animals; amongst others, the singular fact of bud reversion.[116] The curiously recurring development of black sheep, in spite of the most careful breeding, may also be mentioned, though, perhaps, reversion has no part in the phenomenon. These facts seem certainly to tell in favour of limited variability, while the cases of non-reversion do not contradict it, as it is not contended that all species have the same tendency to revert, but rather that their capacities in this respect, as well as for change, are different in different kinds, so that often reversion may only show itself at the end of very long periods indeed. Yet some of the instances given as probable or possible causes of reversion by Mr. Darwin, can hardly be such. He cites, for example, the occasional presence of supernumerary digits in man.[117] For this notion, however, he is not responsible, as he rests his remark on the authority of a {123} passage published by Professor Owen. Again, he refers[118] to "the greater frequency of a monster proboscis in the pig than in any other animal." But with the exception of the peculiar muzzle of the Saiga (or European antelope), the only known proboscidian Ungulates are the elephants and tapirs, and to neither of these has the pig any close affinity. It is rather in the horse than in the pig that we might look for the appearance of a reversionary proboscis, as both the elephants and the tapirs have the toes of the hind foot of an odd number. It is true that the elephants are generally considered to form a group apart from both the odd and the even-toed Ungulata. But of the two, their affinities with the odd-toed division are more marked.[119] Another argument in favour of the, at least intermitting, constancy of specific forms and of sudden modification, may be drawn from the absence of minute transitional forms, but this will be considered in the next chapter. It remains now to notice in favour of specific stability, that the objection drawn from physiological difference between "species" and "races" still exists unrefuted. Mr. Darwin freely admits difficulties regarding the sterility of different species when crossed, and shows satisfactorily that it could never have arisen from the action of "Natural Selection." He remarks[120] also: "With some few exceptions, in the case of plants, domesticated varieties, such as those of the dog, fowl, pigeon, several fruit trees, and culinary vegetables, which differ from each other in external characters more than many species, are perfectly fertile when crossed, or even fertile in {124} excess, whilst closely allied species are almost invariably in some degree sterile." Again, after speaking of "the general law of good being, derived from the intercrossing of distinct individuals of the same species," and the evidence that the pollen of a distinct _variety_ or race is prepotent over a flower's own pollen, adds the very significant remark,[121] "When distinct _species_ are crossed, the case is directly the reverse, for a plant's own pollen is almost always prepotent over foreign pollen." Again he adds:[122] "I believe from observations communicated to me by Mr. Hewitt, who has had great experience in hybridizing pheasants and fowls, that the early death of the embryo is a very frequent cause of sterility in first crosses. Mr. Salter has recently given the results of an examination of about 500 eggs produced from various crosses between three species of Gallus and their hybrids. The majority of these eggs had been fertilized, and in the majority of the fertilized eggs the embryos either had been partially developed and had then aborted, or had become nearly mature, but the young chickens had been unable to break through the shell. Of the chickens which were born, more than four-fifths died within the first few days, or at latest weeks, 'without any obvious cause, apparently from mere inability to live,' so that from 500 eggs only twelve chickens were reared. The early death of hybrid embryos probably occurs in like manner with plants, at least it is known that hybrids raised from very distinct species are sometimes weak and dwarfed, and perish at an early age, of which fact Max Wichura has recently given some striking cases with hybrid willows." Mr. Darwin objects to the notion that there is any special sterility imposed to check specific intermixture and change, saying,[123] "To grant to species the special power of producing hybrids, and then to stop {125} their further propagation by different degrees of sterility, not strictly related to the facility of the first union between their parents, seems a strange arrangement." But this only amounts to saying that the author himself would not have so acted had he been the Creator. A "strange arrangement" must be admitted anyhow, and all who acknowledge teleology at all, must admit that the strange arrangement was designed. Mr. Darwin says, as to the sterility of species, that the cause lies exclusively in their sexual constitution; but all that need be affirmed is that sterility is brought about somehow, and it is undeniable that "crossing" _is_ checked. All that is contended for is that there _is_ a bar to the intermixture of _species_, but not of _breeds_; and if the conditions of the generative products are that bar, it is enough for the argument, no special kind of barring action being contended for. He, however, attempts to account for the modification of the sexual products of species as compared with those of varieties, by the exposure of the former to more uniform conditions during longer periods of time than those to which varieties are exposed, and that as wild animals, when captured, are often rendered sterile by captivity, so the influence of union with another species may produce a similar effect. It seems to the author an unwarrantable assumption that a cross with what, on the Darwinian theory, can only be a slightly diverging descendant of a common parent, should produce an effect equal to that of captivity, and consequent change of habit, as well as considerable modification of food. No clear case has been given by Mr. Darwin in which mongrel animals, descended from the same undoubted species, have been persistently infertile _inter se_; nor any clear case in which hybrids between animals, generally admitted to be distinct species, have been continuously fertile _inter se_. It is true that facts are brought forward tending to establish the probability of the doctrine of Pallas, that species may sometimes be {126} rendered fertile by domestication. But even if this were true, it would be no approximation towards proving the converse, _i.e._ that races and varieties may become sterile when wild. And whatever may be the preference occasionally shown by certain breeds to mate with their own variety, no sterility is recorded as resulting from unions with other varieties. Indeed, Mr. Darwin remarks,[124] "With respect to sterility from the crossing of domestic races, I know of no well-ascertained case with animals. This fact (seeing the great difference in structure between some breeds of pigeons, fowls, pigs, dogs, &c.) is extraordinary when contrasted with the sterility, of many closely-allied natural species when crossed." It has been alleged that the domestic and wild guinea-pig do not breed together, but the specific identity of these forms is very problematical. Mr. A. D. Bartlett, superintendent of the Zoological Gardens, whose experience is so great, and observation so quick, believes them to be decidedly distinct species. Thus, then, it seems that a certain normal specific stability in species, accompanied by occasional sudden and considerable modifications, might be expected _a priori_ from what we know of crystalline inorganic forms and from what we may anticipate with regard to the lowest organic ones. This presumption is strengthened by the knowledge of the increasing difficulties which beset any attempt to indefinitely intensify any race characteristics. The obstacles to this indefinite intensification, as well as to certain lines of variation in certain cases, appear to be not only external, but to depend on internal causes or an internal cause. We have seen that Mr. Darwin himself implicitly admits the principle of specific stability in asserting the singular inflexibility of the organization of the goose. We have also seen that it is not fair to conclude that all wild races can vary as much as the most variable domestic ones. It has also been shown {127} that there are grounds for believing in a tendency to reversion generally, as it is distinctly present in certain instances. Also that specific stability is confirmed by the physiological obstacles which oppose themselves to any considerable or continued intermixture of species, while no such barriers oppose themselves to the blending of varieties. All these considerations taken together may fairly be considered as strengthening the belief that specific manifestations are relatively stable. At the same time the view advocated in this book does not depend upon, and is not identified with, any such stability. All that the Author contends for is that specific manifestation takes place along certain lines, and according to law, and not in an exceedingly minute, indefinite, and fortuitous manner. Finally, he cannot but feel justified, from all that has been brought forward, in reiterating the opening assertion of this chapter that something is still to be said for the view which maintains that species are stable, at least in the intervals of their comparatively rapid successive {128} manifestations. * * * * * CHAPTER VI. SPECIES AND TIME. Two relations of species to time.--No evidence of past existence of minutely intermediate forms when such might be expected _a priori_.--Bats, Pterodactyles, Dinosauria, and Birds.--Ichthyosauria, Chelonia, and Anoura.--Horse ancestry.--Labyrinthodonts and Trilobites.--Two subdivisions of the second relation of species to time.--Sir William Thomson's views.---Probable period required for ultimate specific evolution from primitive ancestral forms.--Geometrical increase of time required for rapidly multiplying increase of structural differences.--Proboscis monkey.--Time required for deposition of strata necessary for Darwinian evolution.--High organization of Silurian forms of life.--Absence of fossils in oldest rocks.--Summary and conclusion. Two considerations present themselves with regard to the necessary relation of species to time if the theory of "Natural Selection" is valid and sufficient. The first is with regard to the evidences of the past existence of intermediate form, their duration and succession. The second is with regard to the total amount of time required for the evolution of all organic forms from a few original ones, and the bearing of other sciences on this question of time. As to the first consideration, evidence is as yet against the modification of species by "Natural Selection" alone, because not only are minutely transitional forms generally absent, but they are absent in cases where we might certainly _a priori_ have expected them to be present. [Page 129] Now it has been said:[125] "If Mr. Darwin's theory be true, the number of varieties differing one from another a very little must have been indefinitely great, so great indeed as probably far to exceed the number of individuals which have existed of any one variety. If this be true, it would be more probable that no two specimens preserved as fossils should be of one variety than that we should find a great many specimens collected from a very few varieties, provided, of course, the chances of preservation are equal for all individuals." "It is really strange that vast numbers of perfectly similar specimens should be found, the chances against their perpetuation as fossils are so great; but it is also very strange that the specimens should be so exactly alike as they are, if, in fact, they came and vanished by a gradual change." Mr. Darwin attempts[126] to show cause why we should believe _a priori_ that intermediate varieties would exist in lesser numbers than the more extreme forms; but though they would doubtless do so sometimes, it seems too much to assert that they would do so generally, still less universally. Now little less than universal and very marked inferiority in numbers would account for the absence of certain series of minutely intermediate fossil specimens. The mass of palæontological evidence is indeed overwhelmingly against minute and gradual modification. It is true that when once an animal has obtained powers of flight its means of diffusion are indefinitely increased, and we might expect to find many relics of an aërial form and few of its antecedent state--with nascent wings just commencing their suspensory power. Yet had such a slow mode of origin, as Darwinians contend for, operated exclusively in all cases, it is absolutely incredible that birds, bats, and pterodactyles should have left the remains they have, and yet not a single relic be preserved in any one instance{130} of any of these different forms of wing in their incipient and relatively imperfect functional condition! [Illustration: WING-BONES OF PTERODACTYLE, BAT, AND BIRD.] Whenever the remains of bats have been found they have presented the exact type of existing forms, and there is as yet no indication of the conditions of an incipient elevation from the ground. The pterodactyles, again, though a numerous group, are all true and perfect pterodactyles, though surely _some_ of the many incipient forms, which on the Darwinian theory have existed, must have had a good chance of preservation. As to birds, the only notable instance in which discoveries recently made appear to fill up an important hiatus, is the interpretation given by Professor Huxley[127] to the remains of Dinosaurian reptiles, and which were noticed in the third chapter of this work. The learned Professor has (as also has Professor Cope in America) shown that in very important {131} and significant points the skeletons of the Iguanodon and of its allies approach very closely to that existing in the ostrich, emeu, rhea, &c. He has given weighty reasons for thinking that the line of affinity between birds and reptiles passes to the birds last named from the Dinosauria rather than from the Pterodactyles, through Archeopteryx-like forms to the ordinary birds. Finally, he has thrown out the suggestion that the celebrated footsteps left by some extinct three-toed creatures on the very ancient sandstone of Connecticut were made, not, as hitherto supposed, by true birds, but by more or less ornithic reptiles. But even supposing all that is asserted or inferred on this subject to be fully proved, it would not approach to a demonstration of specific origin by _minute_ modification. And though it harmonizes well with "Natural Selection," it is equally consistent with the rapid and sudden development of new specific forms of life. Indeed, Professor Huxley, with a laudable caution and moderation too little observed by some Teutonic Darwinians, guarded himself carefully from any imputation of asserting dogmatically the theory of "Natural Selection," while upholding fully the doctrine of evolution. But, after all, it is by no means certain, though very probable, that the Connecticut footsteps were made by very ornithic reptiles, or extremely sauroid birds. And it must not be forgotten that a completely carinate[128] bird (the Archeopteryx) existed at a time, when, as yet, we have no evidence of some of the Dinosauria having come into being. Moreover, if the remarkable and minute similarity of the coracoid of a pterodactyle to that of a bird be merely the result of function and no sign of genetic affinity, it is not inconceivable that pelvic and leg resemblances of Dinosauria to birds may be functional likewise, though such an explanation is, of {132} course, by no means necessary to support the view maintained in this book. [Illustration: THE ARCHEOPTERYX (OF THE OOLITE STRATA).] [Illustration: SKELETON OF AN ICHTHYOSAURUS.] But the number of forms represented by many individuals, yet by _no transitional ones_, is so great that only two or three can be selected as examples. Thus those remarkable fossil reptiles, the Ichthyosauria and Plesiosauria, extended, through the secondary period, probably over the greater part of the globe. Yet no single transitional form has yet been met with in spite of the multitudinous individuals preserved. Again, with their modern representatives the Cetacea, one or two aberrant forms alone {133} have been found, but no series of transitional ones indicating minutely the line of descent. This group, the whales, is a very marked one, and it is curious, on Darwinian principles, that so few instances tending to indicate its mode of origin should have presented themselves. Here, as in the bats, we might surely expect that some relics of unquestionably incipient stages of its development would have been left. [Illustration: SKELETON OF A PLESIOSAURUS.] The singular order Chelonia, including the tortoises, turtles, and terrapins (or fresh-water tortoises), is another instance of an extreme form without any, as yet known, transitional stages. Another group may be finally mentioned, viz. the frogs and toads, anourous Batrachians, of which we have at present no relic of any kind linking them on to the Eft group on the one hand, or to reptiles on the other. The only instance in which an approach towards a series of nearly related forms has been obtained is the existing horse, its predecessor Hipparion and other extinct forms. But even here there is no proof whatever of modification by minute and infinitesimal steps; _a fortiori_ no approach to a proof of modification by "Natural Selection," acting upon indefinite fortuitous variations. On the contrary, the series is an admirable example of successive modification in one special direction along one beneficial line, and the teleologist must here be allowed to consider that one {134} motive of this modification (among probably an indefinite number of motives inconceivable to us) was the relationship in which the horse was to stand to the human inhabitants of this planet. These extinct forms, as Professor Owen, remarks,[129] "differ from each other in a greater degree than do the horse, zebra, and ass," which are not only good _zoological_ species as to form, but are species _physiologically_, _i.e._ they cannot produce a race of hybrids fertile _inter se_. As to the mere action of surrounding conditions, the same Professor remarks:[130] "Any modification affecting the density of the soil might so far relate to the changes of limb-structure, as that a foot with a pair of small hoofs dangling by the sides of the large one, like those behind the cloven hoof of the ox, would cause the foot of Hipparion, _e.g._, and _a fortiori_ the broader based three-hoofed foot of the Palæothere, to sink less deeply into swampy soil, and be more easily withdrawn than the more concentratively simplified and specialized foot of the horse. Rhinoceroses and zebras, however, tread together the arid plains of Africa in the present day; and the horse has multiplied in that half of America where two or more kinds of tapir still exist. That the continents of the Eocene or Miocene periods were less diversified in respect of swamp and sward, pampas or desert, than those of the Pliocene period, has no support from observation or analogy." Not only, however, do we fail to find any traces of the incipient stages of numerous very peculiar groups of animals, but it is undeniable that there are instances which appeared at first to indicate a _gradual transition_, yet which instances have been shown by further investigation and discovery not to indicate truly anything of the kind. Thus at one time the remains of Labyrinthodonts, which up till then had been discovered, seemed to justify the opinion that as time went on, forms had successively appeared with{135} more and more complete segmentation and ossification of the backbone, which in the earliest forms was (as it is in the lowest fishes now) a soft continuous rod or notochord. Now, however, it is considered probable that the soft back-boned Labyrinthodont Archegosaurus, was an immature or larval form,[131] while Labyrinthodonts with completely developed vertebræ have been found to exist amongst the very earliest forms yet discovered. The same may be said regarding the eyes of the trilobites, some of the oldest forms having been found as well furnished in that respect as the very last of the group which has left its remains accessible to observation. [Illustration: TRILOBITE.] Such instances, however, as well as the way in which marked and special forms (as the Pterodactyles, &c., before referred to) appear at once in and similarly disappear from the geological record, are of course explicable on the Darwinian theory, provided a sufficiently enormous amount of past time be allowed. The alleged extreme, and probably great, imperfection of that record may indeed be pleaded in excuse. But it _is_ an excuse.[132] {136} Nor is it possible to deny the _a priori_ probability of the preservation of at least a few _minutely transitional_ forms in some instances if _every_ species without exception has arisen exclusively by such minute and gradual transitions. It remains, then, to turn to the other considerations with regard to the relation of species to time: namely (1) as to the total amount of time allowable by other sciences for organic evolution; and (2) the proportion existing, on Darwinian principles, between the time anterior to the earlier fossils, and the time since; as evidenced by the proportion between the amount of evolutionary change during the latter epoch and that which must have occurred anteriorly. Sir William Thomson has lately[133] advanced arguments from three distinct lines of inquiry, and agreeing in one approximate result. The three lines of inquiry were--1. The action of the tides upon the earth's rotation. 2. The probable length of time during which the sun has illuminated this planet; and 3. The temperature of the interior of the earth. The result arrived at by these investigations is a conclusion that the existing state of things on the earth, life on the earth, all geological history showing continuity of life, must be limited within some such period of past time as one hundred million years. The first question which suggests itself, supposing Sir W. Thomson's views to be correct, is, Is this period anything like enough for the evolution of all organic forms by "Natural Selection"? The second is, Is this period anything like enough for the deposition of the strata which must have been deposited if all organic forms have been evolved by _minute_ steps, according to the Darwinian theory? In the first place, as to Sir William Thomson's views, the Author of this book cannot presume to advance any opinion; but the fact that they have not been refuted, pleads strongly in their favour when we consider how {137} much they tell against the theory of Mr. Darwin. The last-named author only remarks that "many of the elements in the calculation are more or less doubtful,"[134] and Professor Huxley[135] does not attempt to _refute_ Sir W. Thomson's arguments, but only to show cause for suspense of judgment, inasmuch as the facts _may be_ capable of other explanations. Mr. Wallace, on the other hand,[136] seems more disposed to accept them, and, after considering Sir William's objections and those of Mr. Croll, puts the probable date of the beginning of the Cambrian deposits[137] at only twenty-four million years ago. On the other hand, he seems to consider that specific change has been more rapid than generally supposed, and exceptionally stable during the last score or so of thousand years. Now, first, with regard to the time required for the evolution of all organic forms by merely accidental, minute, and fortuitous variations, the useful ones of which have been preserved: Mr. Murphy[138] is distinctly of opinion that there has not been time enough. He says, "I am inclined to think that geological time is too short for the evolution of the higher forms of life out of the lower by that accumulation of imperceptibly slow variations, to which alone Darwin ascribes the whole process." "Darwin justly mentions the greyhound as being equal to any natural species in the perfect co-ordination of its parts, 'all adapted for extreme fleetness and for running down weak prey.'" "Yet it is an artificial species (and not _physiologically_ a species _at all_), formed by long-continued selection under domestication; and there is no reason to suppose that any of the variations which have been selected to form it have been other than gradual and almost imperceptible. Suppose that it has {138} taken five hundred years to form the greyhound out of his wolf-like ancestor. This is a mere guess, but it gives the order of the magnitude." Now, if so, "how long would it take to obtain an elephant from a protozoon, or even from a tadpole-like fish? Ought it not to take much more than a million times as long?"[139] Mr. Darwin[140] would compare with the natural origin of a species "unconscious selection, that is, the preservation of the most useful or beautiful animals, with no intention of modifying the breed." He adds: "But by this process of unconscious selection, various breeds have been sensibly changed in the course of two or three centuries." "Sensibly changed!" but not formed into "new species." Mr. Darwin, of course, could not mean that species _generally_ change so rapidly, which would be strangely at variance with the abundant evidence we have of the stability of animal forms as represented on Egyptian monuments and as shown by recent deposits. Indeed, he goes on to say,--"Species, however, probably change much more slowly, and within the same country only a few change at the same time. This slowness follows from all the inhabitants of the same country being already so well adapted to each other, that places in the polity of nature do not occur until after long intervals, when changes of some kind in the physical conditions, or through immigration, have occurred, and individual differences and variations of the right nature, by which some of the inhabitants might be better fitted to their new places under altered circumstances, might not at once occur." This is true, and not only will these changes occur at distant intervals, but it must be borne in mind that in tracing back an animal to a remote ancestry, we pass through modifications of such rapidly increasing number and importance that a geometrical progression can alone indicate the increase of periods {139} which such profound alterations would require for their evolution through "Natural Selection" only. Thus let us take for an example the proboscis monkey of Borneo (_Semnopithecus nasalis_). According to Mr. Darwin's own opinion, this form might have been "sensibly changed" in the course of two or three centuries. According to this, to evolve it as a true and perfect species one thousand years would be a very moderate period. Let ten thousand years be taken to represent approximately the period of substantially constant conditions during which no considerable change would be brought about. Now, if one thousand years may represent the period required for the evolution of the species _S. nasalis_, and of the other species of the genus Semnopithecus; ten times that period should, I think, be allowed for the differentiation of that genus, the African Cercopithecus and the other genera of the family Simiidæ--the differences between the genera being certainly more than tenfold greater than those between the species of the same genus. Again we may perhaps interpose a period of ten thousand years' comparative repose. For the differentiation of the families Simiidæ and Cebidæ--so very much more distinct and different than any two genera of either family--a period ten times greater should, I believe, be allowed than that required for the evolution of the subordinate groups. A similarly increasing ratio should be granted for the successive developments of the difference between the Lemuroid and the higher forms of primates; for those between the original primate and other root-forms of placental mammals; for those between primary placental and implacental mammals, and perhaps also for the divergence of the most ancient stock of these and of the monotremes, for in all these cases modifications of structure appear to increase in complexity in at least that ratio. Finally, a vast period must be granted for the development of the lowest mammalian type from the primitive stock of the whole vertebrate sub-kingdom. Supposing this primitive stock to have {140} arisen directly from a very lowly organized animal indeed (such as a nematoid worm, or an ascidian, or a jelly-fish), yet it is not easy to believe that less than two thousand million years would be required for the totality of animal development by no other means than minute, fortuitous, occasional, and intermitting variations in all conceivable directions. If this be even an approximation to the truth, then there seem to be strong reasons for believing that geological time is not sufficient for such a process. The second question is, whether there has been time enough for the deposition of the strata which must have been deposited, if all organic forms have been evolved according to the Darwinian theory? Now this may at first seem a question for geologists only, but, in fact, in this matter geology must in some respects rather take its time from zoology than the reverse; for if Mr. Darwin's theory be true, past time down to the deposition of the Upper Silurian strata can have been but a very small fraction of that during which strata have been deposited. For when those Upper Silurian strata were formed, organic evolution had already run a great part of its course, perhaps the longest, slowest, and most difficult part of that course. At that ancient epoch not only were the vertebrate, molluscous, and arthropod types distinctly and clearly differentiated, but highly developed forms had been produced in each of these sub-kingdoms. Thus in the Vertebrata there were fishes not belonging to the lowest but to the very highest groups which are known to have ever been developed, namely, the Elasmobranchs (the highly organized sharks and rays) and the Ganoids, a group now poorly represented, but for which the sturgeon may stand as a type, and which in many important respects more nearly resemble higher Vertebrata than do the ordinary or osseous fishes. Fishes in which the ventral fins are placed in front of the pectoral ones (_i.e._ jugular fishes) have been generally considered to be comparatively modern forms. But Professor Huxley has kindly informed me that he has discovered a {141} jugular fish in the Permian deposits. Amongst the molluscous animals we have members of the very highest known class, namely, the Cephalopods, or cuttle-fish class; and amongst articulated animals we find Trilobites and Eurypterida, which do not belong to any incipient worm-like group, but are distinctly differentiated Crustacea of no low form. [Illustration: CUTTLE-FISH. A. Ventral aspect. B. Dorsal aspect.] We have in all these animal types nervous systems differentiated on distinctly different patterns, fully formed organs of circulation, digestion, excretion, and generation, complexly constructed eyes and other sense organs; in fact, all the most elaborate and complete animal structures built up, and not only once, for in the fishes and mollusca we have (as described in the third chapter of this work) the coincidence of the independently developed organs of sense attaining a nearly similar complexity in two quite distinct forms. If, then, so small an advance {142} has been made in fishes, molluscs, and arthropods since the Upper Silurian deposits, it will probably be within the mark to consider that the period before those deposits (during which all these organs would, on the Darwinian theory, have slowly built up their different perfections and complexities) occupied time at least a hundredfold greater. Now it will be a moderate computation to allow 25,000,000 years for the deposition of the strata down to and including the Upper Silurian. If, then, the evolutionary work done during this deposition, only represents a hundredth part of the sum total, we shall require 2,500,000,000 (two thousand five hundred million) years for the complete development of the whole animal kingdom to its present state. Even one quarter of this, however, would far exceed the time which physics and astronomy seem able to allow for the completion of the process. Finally, a difficulty exists as to the reason of the absence of rich fossiliferous deposits in the oldest strata--if life was then as abundant and varied as, on the Darwinian theory, it must have been. Mr. Darwin himself admits[141] "the case at present must remain inexplicable; and may be truly urged as a valid argument against the views" entertained in his book. Thus, then, we find a wonderful (and on Darwinian principles an all but inexplicable) absence of minutely transitional forms. All the most marked groups, bats, pterodactyles, chelonians, ichthyosauria, anoura, &c., appear at once upon the scene. Even the horse, the animal whose pedigree has been probably best preserved, affords no conclusive evidence of specific origin by infinitesimal, fortuitous variations; while some forms, as the labyrinthodonts and trilobites, which seemed to exhibit gradual change, are shown by further investigation to do nothing of the sort. As regards the time required for evolution (whether estimated by the probably minimum{143} period required for organic change or for the deposition of strata which accompanied that change), reasons have been suggested why it is likely that the past history of the earth does not supply us with enough. First, because of the prodigious increase in the importance and number of differences and modifications which we meet with as we traverse successively greater and more primary zoological groups; and, secondly, because of the vast series of strata necessarily deposited if the period since the Lower Silurian marks but a small fraction of the period of organic evolution. Finally, the absence or rarity of fossils in the oldest rocks is a point at present inexplicable, and not to be forgotten or neglected. Now all these difficulties are avoided if we admit that new forms of animal life of all degrees of complexity appear from time to time with comparative suddenness, being evolved according to laws in part depending on surrounding conditions, in part internal--similar to the way in which crystals (and, perhaps from recent researches, the lowest forms of life) build themselves up according to the internal laws of their component substance, and in harmony and correspondence with all environing influences and conditions. [Page 144] * * * * * CHAPTER VII. SPECIES AND SPACE. The geographical distribution of animals presents difficulties.--These not insurmountable in themselves; harmonize with other difficulties.--Fresh-water fishes.--Forms common to Africa and India; to Africa and South America; to China and Australia; to North America and China; to New Zealand and South America; to South America and Tasmania; to South America and Australia.--Pleurodont lizards.--Insectivorous mammals.--Similarity of European and South American frogs--Analogy between European salmon and fishes of New Zealand, &c. An ancient Antarctic continent probable.--Other modes of accounting for facts of distribution.--Independent origin of closely similar forms.--Conclusion. The study of the distribution of animals over the earth's surface presents us with many facts having certain not unimportant bearings on the question of specific origin. Amongst these are instances which, at least at first sight, appear to conflict with the Darwinian theory of "Natural Selection." It is not, however, here contended that such facts do by any means constitute by themselves obstacles which cannot be got over. Indeed it would be difficult to imagine any obstacles of the kind which could not be surmounted by an indefinite number of terrestrial modifications of surface--submergences and emergences--junctions and separations of continents in all directions and combinations of any desired degree of frequency. All this being supplemented by the intercalation of armies of enemies, multitudes of ancestors of all kinds, and myriads of connecting forms, whose _raison d'être_ may be simply their utility or necessity {145} for the support of the theory of "Natural Selection." Nevertheless, when brought in merely to supplement and accentuate considerations and arguments derived from other sources, in that case difficulties connected with the geographical distribution of animals are not without significance, and are worthy of mention even though, by themselves, they constitute but feeble and more or less easily explicable puzzles which could not alone suffice either to sustain or to defeat any theory of specific origination. Many facts as to the present distribution of animal life over the world are very readily explicable by the hypothesis of slight elevations and depressions of larger and smaller parts of its surface, but there are others the existence of which it is much more difficult so to explain. The distribution either of animals possessing the power of flight, or of inhabitants of the ocean, is, of course, easily to be accounted for; the difficulty, if there is really any, must mainly be with strictly terrestrial animals of moderate or small powers of locomotion and with inhabitants of fresh water. Mr. Darwin himself observes,[142] "In regard to fish, I believe that the same species never occur in the fresh waters of distant continents." Now, the Author is enabled, by the labours and through the kindness of Dr. Günther, to show that this belief cannot be maintained; he having been so obliging as to call attention to the following facts with regard to fish-distribution. These facts show that though only one species which is absolutely and exclusively an inhabitant of fresh water is as yet known to be found in distant continents, yet that in several other instances the same species _is_ found in the fresh water of distant continents, and that very often the same _genus_ is so distributed. The genus _Mastacembelus_ belongs to a family of fresh-water Indian {146} fishes. Eight species of this genus are described by Dr. Günther in his catalogue.[143] These forms extend from Java and Borneo on the one hand, to Aleppo on the other. Nevertheless, a new species (_M. cryptacanthus_) has been described by the same author,[144] which is an inhabitant of the Camaroon country of _Western_ Africa. He observes, "The occurrence of Indian forms on the West Coast of Africa, such as _Periophthalmus_, _Psettus_, _Mastacembelus_, is of the highest interest, and an almost new fact in our knowledge of the geographical distribution of fishes." _Ophiocephalus_, again, is a truly Indian genus, there being no less than twenty-five species,[145] all from the fresh waters of the East Indies. Yet Dr. Günther informs me that there is a species in the Upper Nile and in West Africa. The acanthopterygian family (_Labyrinthici_) contains nine freshwater genera, and these are distributed between the East Indies and South and Central Africa. The Carp fishes (Cyprinoids) are found in India, Africa, and Madagascar, but there are none in South America. Thus existing fresh-water fishes point to an immediate connexion between Africa and India, harmonizing with what we learn from Miocene mammalian remains. On the other hand, the Characinidæ (a family of the physostomous fishes) are found in Africa and South America, and not in India, and even its component groups are so distributed,--namely, the _Tetragonopterina_[146] and the _Hydrocyonina_.[147] Again, we have similar phenomena in that almost exclusively fresh-water group the Siluroids. Thus the genera _Clarias_[148] and _Heterobranchus_[149] are found {147} both in Africa and the East Indies. _Plotosus_ is found in Africa, India, and Australia, and the species _P. anguillaris_[150] has been brought from both China and Moreton Bay. Here, therefore, we have the same species in two distinct geographical regions. It is however a coast fish, which, though entering rivers, yet lives in the sea. _Eutropius_[151] is an African genus, but _E. obtusirostris_ comes from India. On the other hand, _Amiurus_ is a North American form; but one species, _A. cantonensis_,[152] comes from China. The genus _Galaxias_[153] has at least one species common to New Zealand and South America, and one common to South America and Tasmania. In this genus we thus have an absolutely and completely fresh-water form _of the very same species_ distributed between different and distinct geographical regions. Of the lower fishes, a lamprey, _Mordacia mordax_,[154] is common to South Australia and Chile; while another form of the same family, namely, _Geotria chilensis_,[155] is found not only in South America and Australia, but in New Zealand also. These fishes, however, probably pass part of their lives in the sea. We thus certainly have several species which _are_ common to the fresh waters of distant continents, although it cannot be certainly affirmed that they are exclusively and entirely fresh-water fishes throughout all their lives except in the case of _Galaxias_. Existing forms point to a close union between South America and Africa on the one hand, and between South America, Australia, Tasmania, and New Zealand on the other; but these unions were not synchronous any more than the unions indicated between India and Australia, China and Australia, China and North America, and India and Africa. Pleurodont lizards are such as have the teeth attached by their sides {148} to the inner surface of the jaw, in contradistinction to acrodont lizards, which have the bases of their teeth anchylosed to the summit of the margin of the jaw. Now pleurodont iguanian lizards abound in the South American region; but nowhere else, and are not as yet known to inhabit any part of the present continent of Africa. Yet pleurodont lizards, strange to say, are found in Madagascar. This is the more remarkable, inasmuch as we have no evidence yet of the existence in Madagascar of fresh-water fishes common to Africa and South America. [Illustration: INNER SIDE OF LOWER JAW OF PLEURODONT LIZARD. (Showing the teeth attached to the inner surface of its side.)] Again, that remarkable island Madagascar is the home of very singular and special insectivorous beasts of the genera Centetes, Ericulus, and Echinops; while the only other member of the group to which they belong is Solenodon, which is a resident in the West Indian Islands, Cuba and Hayti. The connexion, however, between the West Indies and Madagascar must surely have been at a time when the great lemurine group was absent; for it is difficult to understand the spread of such a form as Solenodon, and at the same time the non-extension of the active lemurs, or their utter extirpation, in such a congenial locality as the West Indian Archipelago. The close connexion of South America and Australia is demonstrated (on the Darwinian theory), not only from the marsupial fauna of both, but also from the frogs and toads which respectively inhabit those regions. A truly remarkable similarity and parallelism exist, however, between certain of the same animals inhabiting South Western America and Europe. Thus Dr.{149} Günther has described[156] a frog from Chile by the name of cacotus, which singularly resembles the European bombinator. [Illustration: SOLENODON.] Again of the salmons, two genera from South America, New Zealand, and Australia, are analogous to European salmons. In addition to this may be mentioned a quotation from Professor Dana, given by Mr. Darwin,[157] to the effect that "it is certainly a wonderful fact that New Zealand should have a closer resemblance in its crustacea to Great Britain, its antipode, than to any other part of the world:" and Mr. Darwin adds "Sir J. Richardson also speaks of the reappearance on the shores of New Zealand, Tasmania, &c. of northern forms of fish. Dr. Hooker informs me that twenty-five species of algæ are common to New Zealand and to {150} Europe, but have not been found in the intermediate tropical seas." Many more examples of the kind could easily be brought, but these must suffice. As to the last-mentioned cases Mr. Darwin explains them by the influence of the glacial epoch, which he would extend actually across the equator, and thus account, amongst other things, for the appearance in Chile of frogs having close genetic relations with European forms. But it is difficult to understand the persistence and preservation of such exceptional forms with the extirpation of all the others which probably accompanied them, if so great a migration of northern kinds had been occasioned by the glacial epoch. Mr. Darwin candidly says,[158] "I am far from supposing that all difficulties in regard to the distribution and affinities of the identical and allied species, which now live so widely separated in the north and south, and sometimes on the intermediate mountain-ranges, are removed." ... "We cannot say why certain species and not others have migrated; why certain species have been modified and have given rise to new forms, whilst others have remained unaltered." Again he adds, "Various difficulties also remain to be solved; for instance, the occurrence, as shown by Dr. Hooker, of the same plants at points so enormously remote as Kerguelen Land, New Zealand, and Fuegia; but icebergs, as suggested by Lyell, may have been concerned in their dispersal. The existence, at these and other distant points of the southern hemisphere, of species which, though distinct, belong to genera exclusively confined to the south, is a more remarkable case. Some of these species are so distinct that we cannot suppose that there has been time since the commencement of the last glacial period for their migration and subsequent modification to the necessary degree." Mr. Darwin goes on to account for these facts by the probable existence of a rich antarctic flora in a warm period anterior to the last glacial {151} epoch. There are indeed many reasons for thinking that a southern continent, rich in living forms, once existed. One such reason is the way in which struthious birds are, or have been, distributed around the antarctic region: as the ostrich in Africa, the rhea in South America, the emeu in Australia, the apteryx, dinornis, &c. in New Zealand, the epiornis in Madagascar. Still the existence of such a land would not alone explain the various geographical cross relations which have been given above. It would not, for example, account for the resemblance between the crustacea or fishes of New Zealand and of England. It would, however, go far to explain the identity (specific or generic) between fresh water and other forms now simultaneously existing in Australia and South America, or in either or both of these, and New Zealand. Again, mutations of elevation small and gradual (but frequent and intermitting), through enormous periods of time--waves, as it were, of land rolling many times in many directions--might be made to explain many difficulties as to geographical distribution, and any cases that remained would probably be capable of explanation, as being isolated but allied animal forms, now separated indeed, but being merely remnants of extensive groups which, at an earlier period, were spread over the surface of the earth. Thus none of the facts here given are any serious difficulty to the doctrine of "evolution," but it is contended in this book that if other considerations render it improbable that the manifestation of the successive forms of life has been brought about by minute, indefinite, and fortuitous variations, then these facts as to geographical distribution intensify that improbability, and are so far worthy of attention. All geographical difficulties of the kind would be evaded if we could concede the probability of the independent origin, in different localities, of the same organic forms in animals high in the scale of nature. {152} Similar causes must produce similar results, and new reasons have been lately adduced for believing, as regards the _lowest organisms_, that the same forms can arise and manifest themselves independently. The difficulty as to higher animals is, however, much greater, as (on the theory of evolution) one acting force must always be the ancestral history in each case, and this force must always tend to go on acting in the same groove and direction in the future as it has in the past. So that it is difficult to conceive that individuals, the ancestral history of which is very different, can be acted upon by all influences, external and internal, in such diverse ways and proportions that the results (unequals being added to unequals) shall be equal and similar. Still, though highly improbable, this cannot be said to be impossible; and if there _is_ an innate law of any kind helping to determine specific evolution, this may more or less, or entirely, neutralize or even reverse the effect of ancestral habit. Thus, it is quite conceivable that a pleurodont lizard might have arisen in Madagascar in perfect independence of the similarly-formed American lacertilia: just as certain teeth of carnivorous and insectivorous marsupial animals have been seen most closely to resemble those of carnivorous and insectivorous placental beasts; just as, again, the paddles of the Cetacea resemble, in the fact of a multiplication in the number of the phalanges, the many-jointed feet of extinct marine reptiles, and as the beak of the cuttle-fish or of the tadpole resembles that of birds. We have already seen (in Chapter III.) that it is impossible, upon any hypothesis, to escape admitting the independent origins of closely similar forms, It may be that they are both more frequent and more important than is generally thought. That closely similar structures may arise without a genetic relationship has been lately well urged by Mr. Ray Lankester.[159] He has brought {153} this notion forward even as regards the bones of the skull in osseous fishes and in mammals. He has done so on the ground that the probable common ancestor of mammals and of osseous fishes was a vertebrate animal of so low a type that it could not be supposed to have possessed a skull differentiated into distinct bony elements--even if it was bony at all. If this was so, then the cranial bones must have had an independent origin in each class, and in this case we have the most strikingly harmonious and parallel results from independent actions. For the bones of the skull in an osseous fish are so closely conformed to those of a mammal, that "both types of skull exhibit many bones in common," though "in each type some of these bones acquire special arrangements and very different magnitudes."[160] And no investigator of homologies doubts that a considerable number of the bones which form the skull of any osseous fish are distinctly homologous with the cranial bones of man. The occipital, the parietal, and frontal, the bones which surround the internal ear, the vomer, the premaxilla, and the quadrate bones, may be given as examples. Now, if such close relations of homology can be brought about independently of any but the most remote genetic affinity, it would be rash to affirm dogmatically that there is any impossibility in the independent origin of such forms as centetes and solenodon, or of genetically distinct batrachians, as similar to each other as are some of the frogs of South America and of Europe. At the same time such phenomena must at present be considered as very improbable, from the action of ancestral habit, as before stated. We have seen, then, that the geographical distribution of animals presents difficulties, though not insuperable ones, for the Darwinian hypothesis. If, however, other reasons against it appear of any weight--if, especially, there is reason to believe that geological time has not been {154} sufficient for it, then it will be well to bear in mind the facts here enumerated. These facts, however, are not opposed to the doctrine of evolution; and if it could be established that closely similar forms had really arisen in complete independence one of the other, they would rather tend to strengthen and to support that theory. [Page 155] * * * * * CHAPTER VIII. HOMOLOGIES. Animals made-up of parts mutually related in various ways.--What homology is.--Its various kinds.--Serial homology.--Lateral homology.--Vertical homology.--Mr. Herbert Spencer's explanations.--An internal power necessary, as shown by facts of comparative anatomy.--Of teratology.--M. St. Hilaire.--Professor Burt Wilder.--Foot-wings.--Facts of pathology.--Mr. James Paget.--Dr. William Budd.--The existence of such an internal power of individual development diminishes the improbability of an analogous law of specific origination. That concrete whole which is spoken of as "an individual" (such, _e.g._, as a bird or a lobster) is formed of a more or less complex aggregation of parts which are actually (from whatever cause or causes) grouped, together in a harmonious interdependency, and which have a multitude of complex relations amongst themselves. The mind detects a certain number of these relations as it contemplates the various component parts of an individual in one or other direction--as it follows up different lines of thought. These perceived relations, though subjective, _as relations_, have nevertheless an objective foundation as real parts, or conditions of parts, of real wholes; they are, therefore, true relations, such, _e.g._, as those between the right and left hand, between the hand and the foot, &c. The component parts of each concrete whole have also a relation of resemblance to the parts of other concrete wholes, whether of the same{156} or of different kinds, as the resemblance between the hands of two men, or that between the hand of a man and the fore-paw of a cat. Now, it is here contended that the relationships borne one to another by various component parts, imply the existence of some innate, internal condition, conveniently spoken of as a power or tendency, which is quite as mysterious as is any innate condition, power, or tendency, resulting in the orderly evolution of successive specific manifestations. These relationships, as also this developmental power, will doubtless, in a certain sense, be somewhat further explained as science advances. But the result will be merely a shifting of the inexplicability a point backwards, by the intercalation of another step between the action of the internal condition or power and its external result. In the meantime, even if by "Natural Selection" we could eliminate the puzzles of the "origin of species," yet other phenomena, not less remarkable (namely, those noticed in this chapter), would still remain unexplained and as yet inexplicable. It is not improbable that, could we arrive at the causes conditioning all the complex inter-relations between the several parts of one animal, we should at the same time obtain the key to unlock the secrets of specific origination. It is desirable, then, to see what facts there are in animal organization which point to innate conditions (powers and tendencies), as yet unexplained, and upon which the theory of "Natural Selection" is unable to throw any explanatory light. The facts to be considered are the phenomena of "homology," and especially of serial, bilateral, and vertical homology. The word "homology" indicates such a relation between two parts that they may be said in some sense to be "the same," or at least "of similar nature." This similarity, however, does not relate to the _use_ to which parts are put, but only to their relative position with regard to other parts, or to their mode of origin. There are many kinds of {157} homology,[161] but it is only necessary to consider the three kinds above enumerated. [Illustration: WINGBONES OF PTERODACTYLE, BAT, AND BIRD.] The term "homologous" may be applied to parts in two individual animals of different kinds, or to different parts of the same individual. Thus "the right and left hands," or "joints of the backbone," or "the teeth of the two jaws," are homologous parts of the same individual. But the arm of a man, the fore-leg of the horse, the paddle of the whale, and the wing of the bat and the bird are all also homologous parts, yet of another kind, _i.e._ they are the same parts existing in animals of different species. On the other hand, the wing of the humming-bird and the wing of the humming-bird moth are not homologous at all, or in any sense; for the resemblance between them consists solely in the use to which they are put, and is therefore only a relation of _analogy_. There is no relation of _homology_ between them, because they have no common resemblance as to their relations to surrounding parts, or as to their mode of origin. Similarly, there is no homology between the wing of the bat and that {158} of the flying-dragon, for the latter is formed of certain ribs, and not of limb bones. [Illustration: SKELETON OF THE FLYING DRAGON. (Showing the elongated ribs which support the flitting organ.)] Homology may be further distinguished into (1) a relationship which, on evolutionary principles, would be due to descent from a common ancestor, as the homological relation between the arm-bone of the horse and that of the ox, or between the singular ankle bones of the two lemurine genera, cheirogaleus and galago, and which relation has been termed by Mr. Ray Lankester "homogeny;"[162] and (2) a relationship induced, not derived--such as exists between parts closely similar in relative position, but with no genetic affinity, or only a remote one, as the homological relation between the chambers of the heart of a bat and those of a {159} bird, or the similar teeth of the thylacine and the dog before spoken of. For this relationship Mr. Bay Lankester has proposed the term "homoplasy." [Illustration: TARSAL BONES OF DIFFERENT LEMUROIDS. (Right tarsus of Galago; left tarsus of Cheirogaleus.)] [Illustration: A CENTIPEDE.] "Serial homology" is a relation of resemblance existing between two or more parts placed in series one behind the other in the same individual. Examples of such homologues are the ribs, or joints of the backbone of{160} a horse, or the limbs of a centipede. The latter animal is a striking example of serial homology. The body (except at its two ends) consists of a longitudinal series of similar segments. Each segment supports a pair of limbs, and the appendages of all the segments (except as before) are completely alike. [Illustration: SQUILLA.] A less complete case of serial homology is presented by Crustacea (animals of the crab class), notably by the squilla and by the common lobster. In the latter animal we have a six-jointed abdomen (the so-called tail), {161} in front of which is a large solid mass (the cephalo-thorax), terminated anteriorly by a jointed process (the rostrum). On the under surface of the body we find a quantity of moveable appendages. Such are, _e.g._, feelers (Fig. 9), jaws (Figs. 6, 7, and 8), foot-jaws (Fig. 5), claws and legs (Figs. 3 and 4), beneath the cephalo-thorax; and flat processes (Fig. 2), called "swimmerets," beneath the so-called tail or abdomen. [Illustration: PART OF THE SKELETON OF THE LOBSTER.] Now, these various appendages are distinct and different enough as we {162} see them in the adult, but they all appear in the embryo as buds of similar form and size, and the thoracic limbs at first consist each of two members, as the swimmerets always do. This shows what great differences may exist in size, in form, and in function, between parts which are developmentally the same, for all these appendages are modifications of one common kind of structure, which becomes differently modified in different situations; in other words, they are serial homologues. The segments of the body, as they follow one behind the other, are also serially alike, as is plainly seen in the abdomen or tail. In the cephalo-thorax of the lobster, however, this is disguised. It is therefore very interesting to find that in the other crustacean before mentioned, the squilla, the segmentation of the body is more completely preserved, and even the first three segments, which go to compose the head, remain permanently distinct. [Illustration: SPINE OF GALAGO ALLENII.] Such an obvious and unmistakeable serial repetition of parts does not obtain in the highest, or backboned animals, the Vertebrata. Thus in man and other mammals, nothing of the kind is _externally_ visible, and we have to penetrate to his skeleton to find such a series of homologous parts. There, indeed, we discover a number of pairs of bones, each pair so obviously resembling the others, that they all receive a common name--the ribs. There also (_i.e._ in the skeleton) we find a still more remarkable series of similar parts, the joints of the spine or backbone (vertebræ), which are admitted by all to possess a certain community of structure.{163} It is in their limbs, however, that the Vertebrata present the most obvious and striking serial homology--almost the only serial homology noticeable externally. The facts of serial homology seem hardly to have excited the amount of interest they certainly merit. Very many writers, indeed, have occupied themselves with investigations and speculations as to what portions of the leg and foot answer to what parts of the arm and hand, a question which has only recently received a more or less satisfactory solution through the successive concordant efforts of Professor Humphry,[163] Professor Huxley,[164] the Author of this work,[165] and Professor Flower.[166] Very few writers, however, have devoted much time or thought to the question of serial homology in general. Mr. Herbert Spencer, indeed, in his very interesting "First Principles of Biology," has given forth ideas on this subject, which are well worthy careful perusal and consideration, and some of which apply also to the other kinds of homology mentioned above. He would explain the serial homologies of such creatures as the lobster and centipede thus: Animals of a very low grade propagate themselves by spontaneous fission. If certain creatures found benefit from this process of division remaining incomplete, such creatures (on the theory of "Natural Selection") would transmit their selected tendency to such incomplete division to their posterity. In this way, it is conceivable, that animals might arise in the form of long chains of similar segments, each of which chains would consist of a number of imperfectly separated individuals, and be equivalent to a series of separate individuals belonging to kinds in which the fission was complete. In other words, Mr. Spencer would explain it as the coalescence of {164} organisms of a lower degree of aggregation in one longitudinal series, through survival of the fittest aggregations. This may be so. It is certainly an ingenious speculation, but facts have not yet been brought forward which demonstrate it. Had they been so, this kind of serial homology might be termed "homogenetic." The other kind of serial repetitions, namely, those of the vertebral column, are explained by Mr. Spencer as the results of alternate strains and compressions acting on a primitively homogeneous cylinder. The serial homology of the fore and hind limbs is explained by the same writer as the result of a similarity in the influences and conditions to which they are exposed. Serial homologues so formed might be called, as Mr. Ray Lankester has proposed, "homoplastic." But there are, it is here contended, abundant reasons for thinking that the predominant agent in the production of the homologies of the limbs is an _internal_ force or tendency. And if such a power can be shown to be necessary in this instance, it may also be legitimately used to explain such serial homologies as those of the centipede's segments and of the joints of the backbone. At the same time it is not, of course, pretended that external conditions do not contribute their own effects in addition. The presence of this internal power will be rendered more probable if valid arguments can be brought forward against the explanations which Mr. Herbert Spencer has offered. _Lateral homology_ (or bilateral symmetry) is the resemblance between the right and left sides of an animal, or of part of an animal; as, _e.g._, between our right hand and our left. It exists more or less at one or other time of life in all animals, except some very lowly organized creatures. In the highest animals this symmetry is laid down at the very dawn of life, the first trace of the future creature being a longitudinal streak--the embryonic "primitive groove." This kind of homology is explained by Mr. Spencer as the result of the similar way in which conditions affect {165} the right and left sides respectively. [Illustration: VERTEBRÆ OF AXOLOTL.] _Vertical homology_ (or vertical symmetry) is the resemblance existing between parts which are placed one above the other beneath. It is much less general and marked than serial, or lateral homology. Nevertheless, it is plainly to be seen in the tail region of most fishes, and in the far-extending dorsal (back) and ventral (belly) fins of such kinds as the sole and the flounder. It is also strikingly shown in the bones of the tail of certain efts, as in _Chioglossa_, where the complexity of the upper (neural) arch is closely repeated by the inferior one. Again, in _Spelerpes rubra_, where almost vertically ascending articular processes above are repeated by almost vertically descending articular processes below. Also in the axolotl, where there are douple pits, placed side by side, not only superiorly but at the same time inferiorly.[167] This kind of homology is also explained by Mr. Spencer as the result of the similarity of conditions affecting the two parts. Thus he explains the very general absence of symmetry between the dorsal and ventral surfaces of animals by the different conditions to which these two surfaces are respectively exposed, and in the same way he explains the asymmetry of the flat-fishes (_Pleuronectidæ_), of snails, &c. Now, first, as regards Mr. Spencer's explanation of animal forms by means of the influence of external conditions, the following observations may be made. Abundant instances are brought forward by him of admirable adaptation of structure to circumstances, but as to the immense majority of these it is very difficult, if not impossible, to see _how_ external conditions{166} can have produced, or even tended to have produced them. For example, we may take the migration of one eye of the sole to the other side of its head. What is there here either in the darkness, or the friction, or in any other conceivable external cause, to have produced the first beginning of such an unprecedented displacement of the eye? Mr. Spencer has beautifully illustrated that correlation which all must admit to exist between the forms of organisms and their surrounding external conditions, but by no means proved that the latter are _the cause_ of the former. [Illustration: PLEURONECTIDÆ, WITH THE PECULIARLY PLACED EYE IN DIFFERENT POSITIONS.] Some internal conditions (or in ordinary language some internal power and force) must be conceded to living organisms, otherwise incident forces must act upon them and upon non-living aggregations of matter in the same way and with similar effects. If the mere presence of these incident forces produces so ready a response in animals and plants, it must be that there are, in their case, conditions disposing and enabling them so to respond, according to the old maxim, _Quicquid recipitur, recipitur ad modum recipientis_, as the same rays of light which bleach a piece of silk, blacken nitrate of silver. If, therefore, we attribute the forms of organisms to the action of {167} external conditions, _i.e._ of incident forces on their modifiable structure, we give but a partial account of the matter, removing a step back, as it were, the action of the internal condition, power, or force which must be conceived as occasioning such ready modifiability. But indeed it is not at all easy to see how the influence of the surface of the ground or any conceivable condition or force can produce the difference which exists between the ventral and dorsal shields of the carapace of a tortoise, or by what differences of merely external causes the ovaries of the two sides of the body can be made equal in a bat and unequal in a bird. [Illustration: AN ECHINUS, OR SEA-URCHIN. (The spines removed from one-half.)] There is, on the other hand, an _a priori_ reason why we should expect to find that the symmetrical forms of all animals are due to internal causes. This reason is the fact that the symmetrical forms of minerals are undoubtedly due to such causes. It is unnecessary here to do more than allude to the beautiful and complex forms presented by inorganic structures. With regard to organisms, however, the wonderful Acanthometræ and the Polycystina may be mentioned as presenting complexities of form which can hardly be thought to be due to other than _internal_ causes. The same may be said of the great group of Echinoderms, with their amazing{168} variety of component parts. If then internal forces can so build up the most varied structures, they are surely capable of producing the serial, lateral, and vertical symmetries which higher animal forms exhibit. Mr. Spencer is the more bound to admit this, inasmuch as in his doctrine of "physiological units" he maintains that these organic atoms of his have an innate power of building up and evolving the whole and perfect animal from which they were in each case derived. To build up and evolve the various symmetries here spoken of is not one whit more mysterious. Directly to refute Mr. Spencer's assertion, however, would require the bringing forward of examples of organisms which are ill-adapted to their positions, and out of harmony with their surroundings--a difficult task indeed.[168] Secondly, as regards the last-mentioned author's explanation of such serial homology as exists in the centipede and its allies, the very groundwork is open to objection. Multiplication by spontaneous fission seems from some recent researches to be much less frequent than has been supposed, and more evidence is required as to the fact of the habitual propagation of _any_ planariæ in this fashion.[169] But even if this were as asserted, {169} nevertheless it fails to explain the peculiar condition presented by _Syllis_ and some other annelids, where a new head is formed at intervals in certain segments of the body. Here there is evidently an innate tendency to the development at intervals of a complex whole. It is not the budding out or spontaneous fission of certain segments, but the transformation in a definite and very peculiar manner of parts which already exist into other and more complex parts. Again, the processes of development presented by some of these creatures do not by any means point to an origin through{170} the linear coalescence of primitively distinct animals by means of imperfect segmentation. Thus in certain Diptera (two winged flies) the legs, wings, eyes, &c., are derived from masses of formative tissue (termed imaginal disks), which by their mutual approximation together build up parts of the head and body,[170] recalling to mind the development of Echinoderms. [Illustration: AN ANNELID DIVIDING SPONTANEOUSLY. (A new head having been formed towards the hinder end of the body of the parent.)] Again, Nicholas Wagner found in certain other Diptera, the Hessian flies, that the larva gives rise to secondary larvæ within it, which develop and burst the body of the primary larva. The secondary larvæ give rise, similarly, to another set within them, and these again to another[171] set. Again, the fact that in _Tænia echinococcus_ one egg produces numerous individuals, tends to invalidate the argument that the increase of segments during development is a relic of specific genesis. Mr. H. Spencer seems to deny serial homology to the mollusca, but it is difficult to see why the shell segments of chiton are not such homologues because the segmentation is superficial. Similarly the external processes of eolis, doris, &c., are good examples of serial homology, as also are plainly the successive chambers of the orthoceratidæ. Nor are parts of a series less serial, because arranged spirally, as in most gasteropods. Mr. Spencer observes of the molluscous as of the vertebrate animal, "You cannot cut it into transverse slices, each of which contains a digestive organ, a respiratory organ, a reproductive organ, &c."[172] But the same may be said of every single arthropod and annelid if it be meant that all these organs are not contained in every possible slice. While if it be meant that parts of all such organs are contained in certain slices, then some of the mollusca may also be included. Another objection to Mr. Spencer's speculation is derived from considerations which have already been stated, as to past time. For if{171} the annulose animals have been formed by aggregation, we ought to find this process much less perfect in the oldest form. But a complete development, such as already obtains in the lobster, &c., was reached by the Eurypterida and Trilobites of the palæozoic strata; and annelids, probably formed mainly like those of the present day, abounded during the deposition of the oldest fossiliferous rocks. [Illustration: TRILOBITE.] Thirdly, and lastly, as regards such serial homology as is exemplified by the backbone of man, there are also several objections to Mr. Spencer's mechanical explanation. On the theory of evolution most in favour, the first Vertebrata were aquatic. Now, as natation is generally effected by repeated and vigorous lateral flexions of the body, we ought to find the segmentation much more complete laterally than on the dorsal and ventral aspects of the spinal column. Nevertheless, in those species which, taken together, constitute a series of more and more distinctly segmented forms, the segmentation gradually increases _all round_ the central part of the spinal column. Mr. Spencer[173] thinks it probable that the sturgeon has retained the notochordal (that is, the primitive, unsegmented) structure because it{172} is sluggish. But Dr. Günther informs me that the sluggishness of the common tope (_Galeus vulgaris_) is much like that of the sturgeon, and yet the bodies of its vertebræ are distinct and well-ossified. Moreover, the great salamander of Japan is much more inert and sluggish than either, and yet it has a well-developed, bony spine. I can learn nothing of the habits of the sharks _Hexanchus_, _Heptanchus_, and _Echinorhinus_, but Müller describes them as possessing a persistent _chorda dorsalis_.[174] It may be they have the habits of the tope, but other sharks are amongst the very swiftest and most active of fishes. In the bony pike (_lepidosteus_), the rigidity of the bony scales by which it is completely enclosed must prevent any excessive flexion of the body, and yet its vertebral column presents a degree of ossification and vertebral completeness greater than that found in any other fish whatever. Mr. Spencer supports his argument by the non-segmentation of the anterior end of the skeletal axis, _i.e._ by the non-segmentation of the skull. But in fact the skull _is_ segmented, and, according to the quasi-vertebral theory of the skull put forward by Professor Huxley,[175] is probably formed of a number of coalesced segments, of some of which the trabeculæ cranii and the mandibular and hyoidean arches are indications. What is, perhaps, most remarkable however is, that the segmentation of the skull--its separation into the three occipital, parietal, and frontal elements--is most complete and distinct in the highest class, and this can have nothing, however remotely, to do with the cause suggested by Mr. Spencer. Thus, then, there is something to be said in opposition to both the aggregational and the mechanical explanations of serial homology. The explanations suggested are very ingenious, yet repose upon a very {173} small basis of fact. Not but that the process of vertebral segmentation may have been sometimes assisted by the mechanical action suggested. It remains now to consider what are the evidences in support of the existence of an internal power, by the action of which these homological manifestations are evolved. It is here contended that there _is_ good evidence of the existence of some such special internal power, and that not only from facts of comparative anatomy, but also from those of teratology[176] and pathology. These facts appear to show, not only that there are homological internal relations, but that they are so strong and energetic as to re-assert and re-exhibit themselves in creatures which, on the Darwinian theory, are the descendants of others in which they were much less marked. They are, in fact, sometimes even more plain and distinct in animals of the highest types than in inferior forms, and, moreover, this deep-seated tendency acts even in diseased and abnormal conditions. Mr. Darwin recognizes[177] these homological relations, and does "not doubt that they may be mastered more or less completely by Natural Selection." He does not, however, give any explanation of these phenomena other than the imposition on them of the name "laws of correlation;" and indeed he says, "The nature of the bond of correlation is frequently quite obscure." Now, it is surely more desirable to make use, if possible, of one conception than to imagine a number of, to all appearance, separate and independent "laws of correlation" between different parts of each animal. [Illustration: THE AARD-VARK (ORYCTEROPUS).] [Illustration: THE PANGOLIN (MANIS).] But even some of these alleged laws hardly appear well founded. Thus Mr. Darwin, in support of such a law of concomitant variation as regards hair and teeth, brings forward the case of Julia Pastrana,[178] and a man {174} of the Burmese Court, and adds,[179] "These cases and those of the hairless dogs forcibly call to mind the fact that the two orders of mammals, namely, the Edentata and Cetacea, which are the most abnormal in their dermal covering, are likewise the most abnormal either by deficiency or redundancy of teeth." The assertion with regard to these orders is certainly true, but it should be borne in mind at the same time that the armadillos, which are much more abnormal than are the American anteaters as regards their dermal covering, in their dentition are less so. The Cape ant-eater, on the other hand, the Aard-vark (Orycteropus), has teeth formed on a type quite different from that existing in any other mammal; yet its hairy coat is not known to exhibit any such strange peculiarity. Again, those remarkable scaly ant-eaters of the Old World--the pangolins (Manis)--stand alone amongst mammals as regards their dermal covering; having been classed {175} with lizards by early naturalists on account of their clothing of scales, yet their mouth is like that of the hairy ant-eaters of the New World. On the other hand, the duck-billed platypus of Australia (Ornithorhynchus) is the only mammal which has teeth formed of horn, yet its furry coat is normal and ordinary. Again, the Dugong and Manatee are dermally alike, yet extremely different as regards the structure and number of their teeth. The porcupine also, in spite of its enormous armature of quills, is furnished with as good a supply of teeth as are the hairy members of the same family, but not with a better one; and in spite of the deficiency of teeth in the hairless dogs, no converse redundancy of teeth has, it is believed, been remarked in Angora cats and rabbits. To say the least, then, this law {176} of correlation presents numerous and remarkable exceptions. [Illustration: DUGONG.] To return, however, to the subject of homological relations: it is surely inconceivable that indefinite variation with survival of the fittest can ever have built up these serial, bilateral, and vertical homologies, without the action of some special innate power or tendency so to build up, possessed by the organism itself in each case. By "special tendency" is meant one the laws and conditions of which are as yet unknown, but which is analogous to the innate power and tendency possessed by crystals similarly, to build up certain peculiar and very definite forms. First, with regard to comparative anatomy. The correspondence between the thoracic and pelvic limbs is notorious. Professor Gegenbaur has lately endeavoured[180] to explain this resemblance by the derivation of each limb from a primitive form of fin. This fin is supposed to have had a marginal external (radial) series of cartilages, each of which supported a series of secondary cartilages, starting from the inner (ulnar) side of the distal part of the supporting marginal piece. The root marginal piece would become the humerus or femur, as the case might be: the second marginal piece, with the piece attached to the inner side of the distal end of the root marginal piece, would together form either the radius and ulna or the tibia and fibula, and so on. Now there is little doubt (from _a priori_ considerations) but that the special differentiation of the limb bones of the higher Vertebrates has been evolved from anterior conditions existing in some fish-like form or other. But the particular view advocated by the learned Professor is open to criticism. Thus, it may be objected against this view, first, that it takes no account of the radial ossicle which becomes so enormous in the mole; secondly, that it does not explain the extra series of ossicles {177} which are formed on the _outer_ (radial or marginal) side of the paddle in the Ichthyosaurus; and thirdly, and most importantly, that even if this had been the way in which the limbs had been differentiated, it would not be at all inconsistent with the possession of an innate power of producing, and an innate tendency to produce similar and symmetrical homological resemblances. It would not be so because resemblances of the kind are found to exist, which, on the Darwinian theory, must be subsequent and secondary, not primitive and ancestral. Thus we find in animals of the eft kind (certain amphibians), in which the tarsus is cartilaginous, that the carpus is cartilaginous likewise. And we shall see in cases of disease and of malformation what a tendency there is to a similar affection of homologous parts. In efts, as Professor Gegenbaur himself has pointed out,[181] there is a striking correspondence between the bones or cartilages supporting the arm, wrist, and fingers, and those sustaining the leg, ankle, and toes, with the exception that the toes exceed the fingers in number by one. [Illustration: SKELETON OF AN ICHTHYOSAURUS.] [Illustration: A. SKELETON OF ANTERIOR EXTREMITY OF AN EFT. B. SKELETON OF POSTERIOR EXTREMITY OF THE SAME.] Yet these animals are far from being the root-forms from which all the Vertebrata have diverged, as is evidenced from the degree of specialization which their structure presents. If they have descended from such {178} primitive forms as Professor Gegenbaur imagines, then they have built up a secondary serial homology--a repetition of similar modifications--fully as remarkable as if it were primary. The Plesiosauria--those extinct marine reptiles of the Secondary period, with long necks, small heads, and paddle-like limbs--are of yet higher organization than are the efts and other Amphibia. Nevertheless they present us with a similarity of structure between the fore and hind limb, which is so great as almost to be {179} identity. But the Amphibia and Plesiosauria, though not themselves primitive vertebrate types, may be thought by some to have derived their limb-structure by direct descent from such. Tortoises, however, must be admitted to be not only highly differentiated organisms, but to be far indeed removed from primeval vertebrate structure. Yet certain tortoises[182] (notably _Chelydra Temminckii_) exhibit such a remarkable uniformity in fore and hind limb structure (extending even up to the proximal ends of the humerus and femur) that it is impossible to doubt its independent development in these forms. [Illustration: SKELETON OF A PLESIOSAURUS.] Again in the Potto (Perodicticus) there is an extra bone in the foot, situated in the transverse ligament enclosing the flexor tendons. It is noteworthy that in the _hand_ of the same animal a serially homologous structure should also be developed.[183] In the allied form called the slow lemur (Nycticebus) we have certain arrangements of the muscles and tendons of the hand which reproduce in great measure those of the foot and _vice versâ_.[184] And in the Hyrax another myological resemblance appears.[185] It is, however, needless to multiply instances which can easily be produced in large numbers if required. Secondly, with regard to teratology, it is notorious that similar abnormalities are often found to co-exist in both the pelvic and thoracic limbs. M. Isidore Geoffroy St. Hilaire remarks,[186] "L'anomalie se répète d'un membre thoracique au membre abdominal du même côté." And he afterwards quotes from Weitbrecht,[187] who had "observé dans un cas l'absence simultanée aux deux mains et aux deux pieds, de quelques doigts, de {180} quelques metacarpiens et metatarsiens, enfin de quelques os du carpe et du tarse." [Illustration: LONG FLEXOR MUSCLES AND TENDONS OF THE HAND. _P.t._ Pronator teres. _F.s._ Flexor sublimis digitorum. _F.p._ Flexor profundus digitorum. _F.l.p._ Flexor longus pollicis.] Professor Burt G. Wilder, in his paper on extra digits,[188] has {181} recorded no less than twenty-four cases where such excess coexisted in both little fingers; also one case in which the right little finger and little toe were so affected; six in which it was both the little fingers and both the little toes; and twenty-two other cases more or less the same, but in which the details were not accurately to be obtained. Mr. Darwin cites[189] a remarkable instance of what he is inclined to regard as the development in the foot of birds of a sort of representation of the wing-feathers of the hand. He says: "In several distinct breeds of the pigeon and fowl the legs and the two outer toes are heavily feathered, so that, in the trumpeter pigeon, they appear like little wings. In the feather-legged bantam, the 'boots,' or feathers, which grow from the outside of the leg, and generally from the two outer toes, have, according to the excellent authority of Mr. Hewitt, been seen to exceed the wing-feathers in length, and in one case were actually nine and a half inches in length! As Mr. Blyth has remarked to me, these leg-feathers resemble the primary wing-feathers, and are totally unlike the fine down which naturally grows on the legs of some birds, such as grouse and owls. Hence it may be suspected that excess of food has first given redundancy to the plumage, and then that the law of homologous variation has led to the development of feathers on the legs, in a position corresponding with those on the wing, namely, on the outside of the tarsi and toes. I am strengthened in this belief by the following curious case of correlation, which for a long time seemed to me utterly inexplicable,--namely, that in pigeons of any breed, if the legs are feathered, the two outer toes are partially connected by skin. These two outer toes correspond with our third and fourth toes. Now, in the wing of the pigeon, or any other bird, the first and fifth digits are wholly aborted; the second is rudimentary, and carries the so-called 'bastard wing;' whilst the third and fourth {182} digits are completely united and enclosed by skin, together forming the extremity of the wing. So that in feather-footed pigeons not only does the exterior surface support a row of long feathers like wing-feathers, but the very same digits which in the wing are completely united by skin become partially united by skin in the feet; and thus, by the law of the correlated variation of homologous parts, we can understand the curious connexion of feathered legs and membrane between the outer toes." Irregularities in the circulating system are far from uncommon, and sometimes illustrate this homological tendency. My friend and colleague Mr. George G. Gascoyen, assistant surgeon at St. Mary's Hospital, has supplied me with two instances of symmetrical affections which have come under his observation. In the first of these the brachial artery bifurcated almost at its origin, the two halves re-uniting at the elbow-joint, and then dividing into the radial and ulnar arteries in the usual manner. In the second case an aberrant artery was given off from the radial side of the brachial artery, again almost at its origin. This aberrant artery anastomosed below the elbow-joint with the radial side of the radial artery. In each of these cases the right and left sides varied in precisely the same manner. Thirdly, as to pathology. Mr. James Paget,[190] speaking of symmetrical diseases, says: "A certain morbid change of structure on one side of the body is repeated in the exactly corresponding part of the other side." He then quotes and figures a diseased lion's pelvis from the College of Surgeons Museum, and says of it: "Multiform as the pattern is in which the new bone, the product of some disease comparable with a human rheumatism, is deposited--a pattern more complex and irregular than the spots upon a map--there is not one spot or line on one side which is not represented, as exactly as it would be in a mirror, on the other. The likeness has more than daguerreotype exactness." He goes on to observe: "I need not {183} describe many examples of such diseases. Any out-patients' room will furnish abundant instances of exact symmetry in the eruptions of eczema, lepra, and psoriasis; in the deformities of chronic rheumatism, the paralyses from lead; in the eruptions excited by iodide of potassium or copaiba. And any large museum will contain examples of equal symmetry in syphilitic ulcerations of the skull; in rheumatic and syphilitic deposits on the tibiæ and other bones; in all the effects of chronic rheumatic arthritis, whether in the bones, the ligaments, or the cartilages; in the fatty and earthy deposits in the coats of arteries."[191] He also considered it to be proved that, "Next to the parts which are symmetrically placed, none are so nearly identical in composition as those which are homologous. For example, the backs of the hands and of the feet, or the palms and soles, are often not only symmetrically, but similarly, affected with psoriasis. So are the elbows and the knees; and similar portions of the thighs and the arms may be found affected with ichthyosis. Sometimes also specimens of fatty and earthy deposits in the arteries occur, in which exact similarity is shown in the plan, though not in the degree, with which the disease affects severally the humeral and femoral, the radial and peroneal, the ulnar and posterior tibial arteries." Dr. William Budd[192] gives numerous instances of symmetry in disease, both lateral and serial. Thus, amongst others, we have one case (William Godfrey), in which the hands and feet were distorted. "The distortion of the right hand is greater than that of the left, of the right foot greater than that of the left foot." In another (Elizabeth Alford) lepra affected the extensor surfaces of the thoracic and pelvic limbs. Again, in the case of skin disease illustrated in Plate III., "The analogy between the {184} elbows and knees is clearly expressed in the fact that these were the only parts affected with the disease."[193] Professor Burt Wilder,[194] in his paper on "Pathological Polarities," strongly supports the philosophical importance of these peculiar relations, adding arguments in favour of antero-posterior homologies, which it is here unnecessary to discuss, enough having been said, it is believed, to thoroughly demonstrate the existence of these deep internal relations which are named lateral and serial homologies. What explanation can be offered of these phenomena? To say that they exhibit a "nutritional relation" brought about by a "balancing of forces" is merely to give a new denomination to the unexplained fact. The changes are, _of course_, brought about by a "nutritional" process, and the symmetry is undoubtedly the result of a "balance of forces," but to say so is a truism. The question is, what is the cause of this "nutritional balancing"? It is here contended that it must be due to an internal cause which at present science is utterly incompetent to explain. It is an internal property possessed by each living organic whole as well as by each non-living crystalline mass, and that there is such internal power or tendency, which may be spoken of as a "polarity," seems to be demonstrated by the instances above given, which can easily be multiplied indefinitely. Mr. Herbert Spencer[195] (speaking of the reproduction, by budding, of a Begonia-leaf) recognizes a power of the kind. He says, "We have, therefore, no alternative but to say that the living particles composing one of these fragments have an innate tendency to arrange themselves into the shape of the organism to which they belong. We must infer that a plant or animal of any species is made up of special units, in all of which there dwells the intrinsic aptitude to aggregate into the form of that species; just as{185} in the atoms of a salt, there dwells the intrinsic aptitude to crystallize in a particular way. It seems difficult to conceive that this can be so; but we see that it _is_ so." ... "For this property there is no fit term. If we accept the word polarity as a name for the force by which inorganic units are aggregated into a form peculiar to them, we may apply this word to the analogous force displayed by organic limits." Dr. Jeffries Wyman,[196] in his paper on the "Symmetry and Homology of Limbs," has a distinct chapter on the "Analogy between Symmetry and Polarity," illustrating it by the effects of magnets on "particles in a polar condition." Mr. J. J. Murphy, after noticing[197] the power which crystals have to repair injuries inflicted on them and the modifications they undergo through the influence of the medium in which they may be formed, goes on to say:[198] "It needs no proof that in the case of spheres and crystals the forms and the structures are the effect, and not the cause, of the formative principles. Attraction, whether gravitative or capillary, produces the spherical form; the spherical form does not produce attraction. And crystalline polarities produce crystalline structure and form; crystalline structure and form do not produce crystalline polarities. The same is not quite so evident of organic forms, but it is equally true of them also." ... "It is not conceivable that the microscope should reveal peculiarities of structure corresponding to peculiarities of habitual tendency in the embryo, which at its first formation has no structure whatever;"[199] and he adds that "there is something quite inscrutable and mysterious" in the formation of a new individual from the germinal {186} matter of the embryo. In another place[200] he says: "We know that in crystals, notwithstanding the variability of form within the limits of the same species, there are definite and very peculiar formative laws, which cannot possibly depend on anything like organic functions, because crystals have no such functions; and it ought not to surprise us if there are similar formative or morphological laws among organisms, which, like the formative laws of crystallization, cannot be referred to any relation of form or structure to function. Especially, I think, is this true of the lowest organisms, many of which show great beauty of form, of a kind that appears to be altogether due to symmetry of growth; as the beautiful star-like rayed forms of the _acanthometræ_, which are low animal organisms not very different from the Foraminifera." Their "definiteness of form does not appear to be accompanied by any corresponding differentiation of function between different parts; and, so far as I can see, the beautiful regularity and symmetry of their radiated forms are altogether due to unknown laws of symmetry of growth, just like the equally beautiful and somewhat similar forms of the compound six-rayed, star-shaped crystals of snow." Altogether, then, it appears that each organism has an innate tendency to develop in a symmetrical manner, and that this tendency is controlled and subordinated by the action of external conditions, and not that this symmetry is superinduced only _ab externo_. In fact, that each organism has its own internal and special laws of growth and development. If, then, it is still necessary to conceive an internal law or "substantial form," moulding each organic being,[201] and directing its development{187} as a crystal is built up, only in an indefinitely more complex manner, it is congruous to imagine the existence of some internal law accounting at the same time for specific divergence as well as for specific identity. A principle regulating the successive evolution of different organic forms is not one whit more mysterious than is the mysterious power by which a particle of structureless sarcode develops successively into an egg, a grub, a chrysalis, a butterfly, when all the conditions, cosmical, physical, chemical, and vital, are supplied, which are the requisite accompaniments to determine such evolution. [Page 188] * * * * * CHAPTER IX. EVOLUTION AND ETHICS. The origin of morals an inquiry not foreign to the subject of this book.--Modern utilitarian view as to that origin.--Mr. Darwin's speculation as to the origin of the abhorrence of incest.--Cause assigned by him insufficient.--Care of the aged and infirm opposed by "Natural Selection;" also self-abnegation and asceticism.--Distinctness of the ideas "right" and "useful."--Mr. John Stuart Mill.--Insufficiency of "Natural Selection" to account for the origin of the distinction between duty and profit.---Distinction of moral acts into "material" and "formal."--No ground for believing that formal morality exists in brutes.--Evidence that it does exist in savages.--Facility with which savages may be misunderstood.--Objections as to diversity of customs.--Mr. Hutton's review of Mr. Herbert Spencer.--Anticipatory character of morals.--Sir John Lubbock's explanation.--Summary and conclusion. Any inquiry into the origin of the notion of "morality"--the conception of "right"--may, perhaps, be considered as somewhat remote from the question of the Genesis of Species; the more so, since Mr. Darwin, at one time, disclaimed any pretension to explain the origin of the higher psychical phenomena of man. His disciples, however, were never equally reticent, and indeed he himself is now not only about to produce a work on man (in which this question must be considered), but he has distinctly announced the extension of the application of his theory to the very phenomena in question. He says:[202] "In the distant future I see open fields for {189} far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history." It may not be amiss then to glance slightly at the question, so much disputed, concerning the origin of ethical conceptions and its bearing on the theory of "Natural Selection." The followers of Mr. John Stuart Mill, of Mr. Herbert Spencer, and apparently, also, of Mr. Darwin, assert that in spite of the great _present_ difference between the ideas "useful" and "right," yet that they are, nevertheless, one in _origin_, and that that origin consisted ultimately of pleasurable and painful sensations. They say that "Natural Selection" has evolved moral conceptions from perceptions of what was useful, _i.e._ pleasurable, by having through long ages preserved a predominating number of those individuals who have had a natural and spontaneous liking for practices and habits of mind useful to the race, and that the same power has destroyed a predominating number of those individuals who possessed a marked tendency to contrary practices. The descendants of individuals so preserved have, they say, come to inherit such a liking and such useful habits of mind, and that at last (finding this inherited tendency thus existing in themselves, distinct from their tendency to conscious self-gratification) they have become apt to regard it as fundamentally distinct, _innate_, and independent of all experience. In fact, according to this school, the idea of "right" is only the result of the gradual accretion of useful predilections which, from time to time, arose in a series of ancestors naturally selected. In this way, "morality" is, as it were, the congealed past experience of the race, and "virtue" becomes no more than a sort of "retrieving," which the thus improved human animal practises by a perfected and inherited habit, regardless of self-gratification, just as the brute animal has acquired the habit of seeking prey and bringing it to his master, instead of devouring it {190} himself. Though Mr. Darwin has not as yet expressly advocated this view, yet some remarks made by him appear to show his disposition to sympathise with it. Thus, in his work on "Animals and Plants under Domestication,"[203] he asserts that "the savages of Australia and South America hold the crime of incest in abhorrence;" but he considers that this abhorrence has probably arisen by "Natural Selection," the ill effects of close interbreeding causing the less numerous and less healthy offspring of incestuous unions to disappear by degrees, in favour of the descendants (greater both in number and strength) of individuals who naturally, from some cause or other, as he suggests, preferred to mate with strangers rather than with close blood-relations; this preference being transmitted and becoming thus instinctive, or habitual, in remote descendants. But on Mr. Darwin's own ground, it maybe objected that this notion fails to account for "abhorrence," and "moral reprobation;" for, as no stream can rise higher than its source, the original "slight feeling" which was _useful_ would have been perpetuated, but would never have been augmented beyond the degree requisite to ensure this beneficial preference, and therefore would not certainly have become magnified into "abhorrence." It will not do to assume that the union of males and females, each possessing the required "slight feeling," must give rise to offspring with an intensified feeling of the same kind; for, apart from reversion, Mr. Darwin has called attention to the unexpected modifications which sometimes result from the union of _similarly_ constituted parents. Thus, for example, he tells us:[204] "If two top-knotted canaries are matched, the young, instead of having very fine top-knots, are generally bald." From examples of this kind, it is fair, on Darwinian principles, to infer that the union of {191} parents who possessed a similar inherited aversion might result in phenomena quite other than the augmentation of such aversion, even if the two aversions should be altogether similar; while, very probably, they might be so different in their nature as to tend to neutralize each other. Besides, the union of parents so similarly emotional would be rare indeed amongst savages, where marriages would be owing to almost anything rather than to congeniality of mind between the spouses. Mr. Wallace tells us,[205] that they choose their wives for "rude health and physical beauty," and this is just what might be naturally supposed. Again, we must bear in mind the necessity there is that _many individuals_ should be similarly and simultaneously affected with this aversion from consanguineous unions; as we have seen in the second chapter, how infallibly variations presented by only a few individuals, tend to be eliminated by mere force of numbers. Mr. Darwin indeed would throw back this aversion, if possible, to a pre-human period; since he speculates as to whether the gorillas or orang-utans, in effecting their matrimonial relations, show any tendency to respect the prohibited degrees of affinity.[206] No tittle of evidence, however, has yet been adduced pointing in any such direction, though surely if it were of such importance and efficiency as to result (through the aid of "Natural Selection" alone) in that "abhorrence" before spoken of, we might expect to be able to detect unmistakeable evidence of its incipient stages. On the contrary, as regards the ordinary apes (for with regard to the highest there is no evidence of the kind) as we see them in confinement, it would be difficult to name any animals less restricted, by even a generic bar, in the gratification of the sexual instinct. And although the conditions under which they have been observed are abnormal, yet these are hardly the animals to present us in a state of nature, with an extraordinary and exceptional sensitiveness in such matters. [Page 192] To take an altogether different case. Care of, and tenderness towards, the aged and infirm are actions on all hands admitted to be "right;" but it is difficult to see how such actions could ever have been so useful to a community as to have been seized on and developed by the exclusive action of the law of the "survival of the fittest." On the contrary, it seems probable that on strict utilitarian principles the rigid political economy of Tierra del Fuego would have been eminently favoured and diffused by the impartial action of "Natural Selection" alone. By the rigid political economy referred to, is meant that destruction and utilization of "useless mouths" which Mr. Darwin himself describes in his highly interesting "Journal of Researches."[207] He says: "It is certainly true, that when pressed in winter by hunger, they kill and devour their old women before they kill their dogs. The boy being asked why they did this, answered, 'Doggies catch otters, old women no.' They often run away into the mountains, but they are pursued by the men and brought back to the slaughter-house at their own firesides." Mr. Edward Bartlett, who has recently returned from the Amazons, reports that at one Indian village where the cholera made its appearance, the whole population immediately dispersed into the woods, leaving the sick to perish uncared for and alone. Now, had the Indians remained, undoubtedly far more would have died; as doubtless, in Tierra del Fuego, the destruction of the comparatively useless old women has often been the means of preserving the healthy and reproductive young. Such acts surely must be greatly favoured by the stern and unrelenting action of exclusive "Natural Selection." In the same way that admiration which all feel for acts of self-denial done for the good of others, and tending even towards the destruction of the actor, could hardly be accounted for on Darwinian principles alone; for self-immolators must but rarely leave direct descendants, while the community they benefit must by their destruction tend, so far, to {193} morally deteriorate. But devotion to others of the same community is by no means _all_ that has to be accounted for. Devotion to the whole human race, and devotion to God--in the form of asceticism--have been and are very generally recognized as "good;" and the Author contends that it is simply impossible to conceive that such ideas and sanctions should have been developed by "Natural Selection" alone, from only that degree of unselfishness necessary for the preservation of brutally barbarous communities in the struggle for life. That degree of unselfishness once attained, further improvement would be checked by the mutual opposition of diverging moral tendencies and spontaneous variations in all directions. Added to which, we have the principle of reversion and atavism, tending powerfully to restore and reproduce that more degraded anterior condition whence the later and better state painfully emerged. Very few, however, dispute the complete distinctness, here and now, of the ideas of "duty" and "interest" whatever may have been the origin of those ideas. No one pretends that ingratitude may, in any past abyss of time, have been a virtue, or that it may be such now in Arcturus or the Pleiades. Indeed, a certain eminent writer of the utilitarian school of ethics has amusingly and very instructively shown how radically distinct even in his own mind are the two ideas which he nevertheless endeavours to identify. Mr. John Stuart Mill, in his examination of "Sir William Hamilton's Philosophy," says,[208] if "I am informed that the world is ruled by a being whose attributes are infinite, but what they are we cannot learn, nor what the principles of his government, except that 'the highest human morality which we are capable of conceiving' does not sanction them; convince me of it, and I will bear my fate as I may. But when I am told that I must believe this, and at the same time call this being by the {194} names which express and affirm the highest human morality, I say in plain terms that I will not. Whatever power such a being may have over me, there is one thing which he shall not do: he shall not compel me to worship him. I will call no being good, who is not what I mean when I apply that epithet to my fellow-creatures; and if such a being can sentence me to hell for not so calling him, to hell I will go." This is unquestionably an admirable sentiment on the part of Mr. Mill (with which every absolute moralist will agree), but it contains a complete refutation of his own position, and is a capital instance[209] of the vigorous life of moral intuition in one who professes to have eliminated any fundamental distinction between the "right" and the "expedient." For if an action is morally good, and to be done, merely in proportion to the amount of pleasure it secures, and morally bad and to be avoided as tending to misery, and if it could be _proved_ that by calling God good--whether He is so or not, in our sense of the term,--we could secure a maximum of pleasure, and by refusing to do so we should incur endless torment, clearly, on utilitarian principles, the flattery would be good. Mr. Mill, of course, must also mean that, in the matter in question, all men would do well to act with him. Therefore, he must mean that it would be well for all to accept (on the hypothesis above given) infinite and final misery for all as the result of the pursuit of happiness as the only end. It must be recollected that in consenting to worship this unholy God, Mr. Mill is not asked to do harm to his neighbour, so that his refusal reposes simply on his perception of the immorality of the requisition. It is also noteworthy that an omnipotent Deity is supposed incapable of altering Mr. Mill's mind and moral perceptions. Mr. Mill's decision is right, but it is difficult indeed to see how, {195} without the recognition of an "absolute morality," he can justify so utter and final an abandonment of all utility in favour of a clear and distinct moral perception. These two ideas, the "right" and the "useful," being so distinct here and now, a greater difficulty meets us with regard to their origin from some common source, than met us before when considering the first beginnings of certain bodily structures. For the distinction between the "right" and the "useful" is so fundamental and essential that not only does the idea of benefit not enter into the idea of duty, but we see that the very fact of an act _not_ being beneficial to us makes it the more praiseworthy, while gain tends to diminish the merit of an action. Yet this idea, "right," thus excluding, as it does, all reference to utility or pleasure, has nevertheless to be constructed and evolved from utility and pleasure, and ultimately from pleasurable sensations, if we are to accept pure Darwinianism: if we are to accept, that is, the evolution of man's psychical nature and highest powers, by the exclusive action of "Natural Selection," from such faculties as are possessed by brutes; in other words, if we are to believe that the conceptions of the highest human morality arose through minute and fortuitous variations of brutal desires and appetites in all conceivable directions. It is here contended, on the other hand, that no conservation of any such variations could ever have given rise to the faintest beginning of any such moral perceptions; that by "Natural Selection" alone the maxim _fiat justitia, ruat coelum_ could never have been excogitated, still less have found a widespread acceptance; that it is impotent to suggest even an approach towards an explanation of the _first beginning_ of the idea of "right." It need hardly be remarked that acts may be distinguished not only as pleasurable, useful, or beautiful, but also as good in two different senses: (1) _materially_ moral acts, and (2) acts which are _formally_ moral. The first are acts good in themselves, _as acts_, apart from any intention of the agent which may or may not have been directed towards{196} "right." The second are acts which are good not only in themselves, as acts, but also in the deliberate _intention_ of the agent who recognizes his actions as being "right." Thus acts may be _materially_ moral or immoral, in a very high degree, without being in the least _formally_ so. For example, a person may tend and minister to a sick man with scrupulous care and exactness, having in view all the time nothing but the future reception of a good legacy. Another may, in the dark, shoot his own father, taking him to be an assassin, and so commit what is _materially_ an act of parricide, though _formally_ it is only an act of self-defence of more or less culpable rashness. A woman may innocently, because ignorantly, marry a married man, and so commit a _material_ act of adultery. She may discover the facts, and persist, and so make her act _formal_ also. Actions of brutes, such as those of the bee, the ant, or the beaver, however materially good as regards their relation to the community to which such animals belong, are absolutely destitute of the most incipient degree of real, _i.e._ formal "goodness," because unaccompanied by mental acts of conscious will directed towards the fulfilment of duty. Apology is due for thus stating so elementary a distinction, but the statement is not superfluous, for confusion of thought, resulting from confounding together these very distinct things, is unfortunately far from uncommon. Thus some Darwinians assert that the germs of morality exist in brutes, and we have seen that Mr. Darwin himself speculates on the subject as regards the highest apes. It may safely be affirmed, however, that there is no trace in brutes of any actions simulating morality which are not explicable by the fear of punishment, by the hope of pleasure, or by personal affection. No sign of moral reprobation is given by any brute, and yet had such existed in germ through Darwinian abysses of past time, some evidence of its existence must surely have been rendered perceptible through "survival of the fittest" in other forms besides man, if that {197} "survival" has alone and exclusively produced it in him. Abundant examples may, indeed, be brought forward of useful acts which simulate morality, such as parental care of the young, &c. But did the most undeviating habits guide all brutes in such matters, were even aged and infirm members of a community of insects or birds carefully tended by young which benefited by their experience, such acts would not indicate even the faintest rudiment of real, _i.e._ formal, morality. "Natural Selection" would, of course, often lead to the prevalence of acts beneficial to a community, and to acts _materially_ good; but unless they can be shown to be _formally_ so, they are not in the least to the point, they do not offer any explanation of the origin of an altogether new and fundamentally different motive and conception. It is interesting, on the other hand, to note Mr. Darwin's statement as to the existence of a distinct moral feeling, even in, perhaps, the very lowest and most degraded of all the human races known to us. Thus in the same "Journal of Researches"[210] before quoted, bearing witness to the existence of moral reprobation on the part of the Fuegians, he says: "The nearest approach to religious feeling which I heard of was shown by York Minster (a Fuegian so named), who, when Mr. Bynoe shot some very young ducklings as specimens, declared in the most solemn manner, 'Oh, Mr. Bynoe, much rain, snow, blow much.' This was evidently a retributive punishment for wasting human food." Mr. Wallace gives the most interesting testimony, in his "Malay Archipelago," to the existence of a very distinct, and in some instances highly developed moral sense in the natives with whom he came in contact. In one case,[211] a Papuan who had been paid in advance for bird-skins and who had not been able to fulfil his contract before Mr. Wallace was on{198} the point of starting, "came running down after us holding up a bird, and saying with great satisfaction, 'Now I owe you nothing!'" And this though he could have withheld payment with complete impunity. Mr. Wallace's observations and opinions on this head seem hardly to meet with due appreciation in Sir John Lubbock's recent work on Primitive Man.[212] But considering the acute powers of observation and the industry of Mr. Wallace, and especially considering the years he passed in familiar and uninterrupted intercourse with natives, his opinion and testimony should surely carry with it great weight. He has informed the Author that he found a strongly marked and widely diffused modesty, in sexual matters, amongst all the tribes with which he came in contact. In the same way Mr. Bonwick, in his work on the Tasmanians, testifies to the modesty exhibited by the naked females of that race, who by the decorum of their postures gave evidence of the possession in germ of what under circumstances would become the highest chastity and refinement. Hasty and incomplete observations and inductions are prejudicial enough to physical science, but when their effect is to degrade untruthfully our common humanity, there is an additional motive to regret them. A hurried visit to a tribe, whose language, traditions and customs are unknown, is sometimes deemed sufficient for "smart" remarks as to "ape characters," &c., which are as untrue as irrelevant. It should not be forgotten how extremely difficult it is to enter into the ideas and feelings of an alien race. If in the nineteenth century a French theatrical audience can witness with acquiescent approval, as a type of English manners and ideas, the representation of a marquis who sells his wife at Smithfield, &c. &c., it is surely no wonder if the ideas of a tribe of newly visited savages {199} should be more or less misunderstood. To enter into such ideas requires long and familiar intimacy, like that experienced by the explorer of the Malay Archipelago. From him, and others, we have abundant evidence that moral ideas exist, at least in germ, in savage races of men, while they sometimes attain even a highly developed state. No amount of evidence as to acts of moral depravity is to the point, as the object here aimed at is to establish that moral intuitions _exist_ in savages, not that their actions are good. Objections, however, are sometimes drawn from the different notions as to the moral value of certain acts, entertained by men of various countries or of different epochs; also from the difficulty of knowing what particular actions in certain cases are the right ones, and from the effects which prejudice, interest, passion, habit, or even, indirectly, physical conditions, may have upon our moral perceptions. Thus Sir John Lubbock speaks[213] of certain Feejeeans, who, according to the testimony of Mr. Hunt,[214] have the custom of piously choking their parents under certain circumstances, in order to insure their happiness in a future life. Should any one take such facts as telling _against_ the belief in an absolute morality, he would show a complete misapprehension of the point in dispute; for such facts tell in _favour_ of it. Were it asserted that man possesses a distinct innate power and faculty by which he is made intuitively aware what acts considered in and by themselves are right and what wrong,--an infallible and universal internal code,--the illustration would be to the point. But all that need be contended for is that the intellect perceives not only truth, but also a quality of "higher" which ought to be followed, and of "lower" which ought to be avoided; when two lines of conduct are presented to the will for choice, the intellect so acting being the conscience. {200} This has been well put by Mr. James Martineau in his excellent essay on Whewell's Morality. He says,[215] "If moral good were a quality resident in each action, as whiteness in snow, or sweetness in fruits; and if the moral faculty was our appointed instrument for detecting its presence; many consequences would ensue which are at variance with fact. The wide range of differences observable in the ethical judgments of men would not exist; and even if they did, could no more be reduced and modified by discussion than constitutional differences of hearing or of vision. And, as the quality of moral good either must or must not exist in every important operation of the will, we should discern its presence or absence separately in each; and even though we never had the conception of more than one insulated action, we should be able to pronounce upon its character. This, however, we have plainly no power to do. Every moral judgment is relative, and involves a comparison of two terms. When we praise what _has been_ done, it is with the coexistent conception of something _else_ that _might have been_ done; and when we resolve on a course as right, it is to the exclusion of some other that is wrong. This fact, that every ethical decision is in truth a _preference_, an election of one act as higher than another, appears of fundamental importance in the analysis of the moral sentiments." From this point of view it is plain how trifling are arguments drawn from the acts of a savage, since an action highly immoral in us might be one exceedingly virtuous in him--being the highest presented to his choice in his degraded intellectual condition and peculiar circumstances. It need only be contended, then, that there _is_ a perception of "right" incapable of further analysis; not that there is any infallible internal guide as to all the complex actions which present themselves for {201} choice. The _principle_ is given in our nature, the _application_ of the principle is the result of a thousand educational influences. It is no wonder, then, that, in complex "cases of conscience," it is sometimes a matter of exceeding difficulty to determine which of two courses of action is the less objectionable. This no more invalidates the truth of moral principles than does the difficulty of a mathematical problem cast doubt on mathematical principles. Habit, education, and intellectual gifts facilitate the correct application of both. Again, if our moral insight is intensified or blunted by our habitual wishes or, indirectly, by our physical condition, the same may be said of our perception of the true relations of physical facts one to another. An eager wish for marriage has led many a man to exaggerate the powers of a limited income, and a fit of dyspepsia has given an unreasonably gloomy aspect to more than one balance-sheet. Considering that moral intuitions have to do with _insensible_ matters, they cannot be expected to be more clear than the perception of physical facts. And if the latter perceptions may be influenced by volition, desire, or health, our moral views may also be expected to be so influenced, and this in a higher degree because they so often run counter to our desires. A bottle or two of wine may make a sensible object appear double; what wonder, then, if our moral perceptions are sometimes warped and distorted by such powerful agencies as an evil education or an habitual absence of self-restraint. In neither case does occasional distortion invalidate the accuracy of normal and habitual perception. The distinctness here and now of the ideas of "right" and "useful" is however, as before said, fully conceded by Mr. Herbert Spencer, although he contends that these conceptions are one in root and origin. His utilitarian Genesis of Morals, however, has been recently combated{202} by Mr. Richard Holt Hutton in a paper which appeared in _Macmillan's Magazine_.[216] This writer aptly objects an _argumentum ad hominem_, applying to morals the same argument that has been applied in this work to our sense of musical harmony, and by Mr. Wallace to the vocal organs of man. Mr. Herbert Spencer's notions on the subject are thus expressed by himself: "To make my position fully understood, it seems needful to add that, corresponding to the fundamental propositions of a developed moral science, there have been, and still are developing in the race certain fundamental moral intuitions; and that, though these moral intuitions are the result of accumulated experiences of utility gradually organized and inherited, they have come to be quite independent of conscious experience. Just in the same way that I believe the intuition of space possessed by any living individual to have arisen from organized and consolidated experiences of all antecedent individuals, who bequeathed to him their slowly developed nervous organizations; just as I believe that this intuition, requiring only to be made definite and complete by personal experiences, has practically become a form of thought quite independent of experience;--so do I believe that the experiences of utility, organized and consolidated through all past generations of the human race, have been producing corresponding nervous modifications which, by continued transmissions and accumulation, have become in us certain faculties of moral intuition, active emotions responding to right and wrong conduct, which have no apparent basis in the individual experiences of utility. I also hold that, just as the space intuition responds to the exact demonstrations of geometry, and has its rough conclusions interpreted and verified by them, so will moral intuitions respond to the demonstrations of moral science, and will have their rough conclusions interpreted and verified by them." {203} Against this view of Mr. Herbert Spencer, Mr. Hutton objects--"1. That even as regards Mr. Spencer's illustration from geometrical intuitions, his process would be totally inadequate, since you could not deduce the necessary space intuition of which he speaks from any possible accumulations of familiarity with space relations.... We cannot _inherit_ more than our fathers _had_: no amount of experience of facts, however universal, can give rise to that particular characteristic of intuitions and _a priori_ ideas, which compels us to deny the possibility that in any other world, however otherwise different, our experience (as to space relations) could be otherwise. "2. That the case of moral intuitions is very much stronger. "3. That if Mr. Spencer's theory accounts for anything, it accounts not for the deepening of a sense of utility and inutility into right and wrong, but for the drying up of the sense of utility and inutility into mere inherent tendencies, which would exercise over us not _more_ authority but _less_, than a rational sense of utilitarian issues. "4. That Mr. Spencer's theory could not account for the intuitional sacredness now attached to _individual_ moral rules and principles, without accounting _a fortiori_ for the general claim of the greatest happiness principle over us as the final moral intuition---which is conspicuously contrary to the fact, as not even the utilitarians themselves plead any instinctive or intuitive sanction for their great principle. "5. That there is no trace of positive evidence of any single instance of the transformation of a utilitarian rule of right into an intuition, since we find no utilitarian principle of the most ancient times which is now an accepted moral intuition, nor any moral intuition, however sacred, which has not been promulgated thousands of years ago, and which has not constantly had to stop the tide of utilitarian _objections_ to its authority--and this age after age, in our own day quite as much as in days gone by.... Surely, if anything is remarkable in the history of {204} morality, it is the _anticipatory_ character, if I may use the expression, of moral principles--the intensity and absoluteness with which they are laid down ages before the world has approximated to the ideal thus asserted." Sir John Lubbock, in his work on Primitive Man before referred to, abandons Mr. Spencer's explanation of the genesis of morals while referring to Mr. Hutton's criticisms on the subject. Sir John proposes to substitute "deference to authority" instead of "sense of interest" as the origin of our conception of "duty," saying that what has been found to be beneficial has been traditionally inculcated on the young, and thus has become to be dissociated from "interest" in the mind, though the inculcation itself originally sprung from that source. This, however, when analysed, turns out to be a distinction without a difference. It is nothing but utilitarianism, pure and simple, after all. For it can never be intended that authority is obeyed because of an intuition that it _should be deferred to_, for that would be to admit the very principle of absolute morality which Sir John combats. It must be meant, then, that authority is obeyed through fear of the consequences of disobedience, or through pleasure felt in obeying the authority which commands. In the latter case we have "pleasure" as the end and no rudiment of the conception "duty." In the former we have fear of punishment, which appeals directly to the sense of "utility to the individual," and no amount of such a sense will produce the least germ of "ought" which is a conception different _in kind_, and in which the notion of "punishment" has no place. Thus, Sir John Lubbock's explanation only concerns a _mode_ in which the sense of "duty" may be stimulated or appealed to, and makes no approximation to an explanation of its origin. Could the views of Mr. Herbert Spencer, of Mr. Mill, or of Mr. Darwin on this subject be maintained, or should they come to be generally accepted, the consequences would be disastrous indeed! Were it really the case that virtue was a _mere kind of "retrieving,"_ then certainly we should {205} have to view with apprehension the spread of intellectual cultivation, which would lead the human "retrievers" to regard from a new point of view their fetching and carrying. We should be logically compelled to acquiesce in the vociferations of some continental utilitarians, who would banish altogether the senseless words "duty" and "merit;" and then, one important influence which has aided human progress being withdrawn, we should be reduced to hope that in this case the maxim _cessante causa cessat ipse effectus_ might through some incalculable accident fail to apply. It is true that Mr. Spencer tries to erect a safeguard against such moral disruption, by asserting that for every immoral act, word, or thought, each man during this life receives minute and exact retribution, and that thus a regard for individual self-interest will effectually prevent any moral catastrophe. But by what means will he enforce the acceptance of a dogma which is not only incapable of proof, but is opposed to the commonly received opinion of mankind in all ages? Ancient literature, sacred and profane, teems with protests against the successful evil-doer, and certainly, as Mr. Hutton observes,[217] "Honesty must have been associated by our ancestors with many unhappy as well as many happy consequences, and we know that in ancient Greece dishonesty was openly and actually associated with happy consequences.... When the concentrated experience of previous generations was held, _not_ indeed to justify, but to excuse by utilitarian considerations, craft, dissimulation, sensuality, selfishness." This dogma is opposed to the moral consciousness of many as to the events of their own lives; and the Author, for one, believes that it is absolutely contrary to fact. History affords multitudes of instances, but an example may be selected from one of the most critical periods of modern times. Let it be {206} granted that Lewis the Sixteenth of France and his queen had all the defects attributed to them by the most hostile of serious historians; let all the excuses possible be made for his predecessor, Lewis the Fifteenth, and also for Madame de Pompadour, can it be pretended that there are grounds for affirming that the vices of the two former so far exceeded those of the latter, that their respective fates were plainly and evidently just? that while the two former died in their beds, after a life of the most extreme luxury, the others merited to stand forth through coming time as examples of the most appalling and calamitous tragedy? This theme, however, is too foreign to the immediate matter in hand to be further pursued, tempting as it is. But a passing protest against a superstitious and deluding dogma may stand,--a dogma which may, like any other dogma, be vehemently asserted and maintained, but which is remarkable for being destitute, at one and the same time, of both authoritative sanction and the support of reason and observation. To return to the bearing of moral conceptions on "Natural Selection," it seems that, from the reasons given in this chapter, we may safely affirm--1. That "Natural Selection" could not have produced, from the sensations of pleasure and pain experienced by brutes, a higher degree of morality than was useful; therefore it could have produced any amount of "beneficial habits," but not abhorrence of certain acts as impure and sinful. 2. That it could not have developed that high esteem for acts of care and tenderness to the aged and infirm which actually exists, but would rather have perpetuated certain low social conditions which obtain in some savage localities. 3. That it could not have evolved from ape sensations the noble virtue of a Marcus Aurelius, or the loving but manly devotion of a St. Lewis. 4. That, alone, it could not have given rise to the maxim _fiat justitia, ruat coelum_. [Page 207] 5. That the interval between material and formal morality is one altogether beyond its power to traverse. Also, that the anticipatory character of moral principles is a fatal bar to that explanation of their origin which is offered to us by Mr. Herbert Spencer. And, finally, that the solution of that origin proposed recently by Sir John Lubbock is a mere version of simple utilitarianism, appealing to the pleasure or safety of the individual, and therefore utterly incapable of solving the riddle it attacks. Such appearing to be the case as to the power of "Natural Selection," we, nevertheless, find moral conceptions--_formally_ moral ideas--not only spread over the civilized world, but manifesting themselves unmistakeably (in however rudimentary a condition, and however misapplied) amongst the lowest and most degraded of savages. If from amongst these, individuals can be brought forward who seem to be destitute of any moral conception, similar cases also may easily be found in highly civilized communities. Such cases tell no more against moral intuitions than do cases of colour-blindness or idiotism tell against sight and reason. We have thus a most important and conspicuous fact, the existence of which is fatal to the theory of "Natural Selection," as put forward of late by Mr. Darwin and his most ardent followers. It must be remarked, however, that whatever force this fact may have against a belief in the origination of man from brutes by minute, fortuitous variations, it has no force whatever against the conception of the orderly evolution and successive manifestation of specific forms by ordinary natural law--even if we include amongst such the upright frame, the ready hand and massive brain of man himself. [Page 208] * * * * * CHAPTER X. PANGENESIS. A provisional hypothesis supplementing "Natural Selection."--Statement of the hypothesis.--Difficulty as to multitude of gemmules.--As to certain modes of reproduction.--As to formations without the requisite gemmules.--Mr. Lewes and Professor Delpino.--Difficulty as to developmental force of gemmules.--As to their spontaneous fission.--Pangenesis and Vitalism.--Paradoxical reality.--Pangenesis scarcely superior to anterior hypotheses.--Buffon.--Owen.--Herbert Spencer.--"Gemmules" as mysterious as "physiological units."--Conclusion. In addition to the theory of "Natural Selection," by which it has been attempted to account for the origin of species, Mr. Darwin has also put forward what he modestly terms "a provisional hypothesis" (that of _Pangenesis_), by which to account for the origin of each and every individual form. Now, though the hypothesis of Pangenesis is no necessary part of "Natural Selection," still any treatise on specific origination would be incomplete if it did not take into consideration this last speculation of Mr. Darwin. The hypothesis in question may be stated as follows: That each living organism is ultimately made up of an almost infinite number of minute particles, or organic atoms, termed "gemmules," each of which has the power of reproducing its kind. Moreover, that these particles circulate freely about the organism which is made up of them, and are derived from all the parts of all the organs of the less remote ancestors of each such {209} organism during all the states and stages of such several ancestors' existence; and therefore of the several states of each of such ancestors' organs. That such a complete collection of gemmules is aggregated in each ovum and spermatozoon in most animals, and in each part capable of reproducing by gemmation (budding) in the lowest animals and in plants. Therefore in many of such lower organisms such a congeries of ancestral gemmules must exist in every part of their bodies, since in them every part is capable of reproducing by gemmation. Mr. Darwin must evidently admit this, since he says: "It has often been said by naturalists that each cell of a plant has the actual or potential capacity of reproducing the whole plant; but it has this power only in virtue of containing gemmules _derived from every part_."[218] Moreover, these gemmules are supposed to tend to aggregate themselves, and to reproduce in certain definite relations to other gemmules. Thus, when the foot of an eft is cut off, its reproduction is explained by Mr. Darwin as resulting from the aggregation of those floating gemmules which come next in order to those of the cut surface, and the successive aggregations of the other kinds of gemmules which come after in regular order. Also, the most ordinary processes of repair are similarly accounted for, and the successive development of similar parts and organs in creatures in which such complex evolutions occur is explained in the same way, by the independent action of separate gemmules. In order that each living creature may be thus furnished, the number of such gemmules in each must be inconceivably great. Mr. Darwin says:[219] "In a highly organized and complex animal, the gemmules thrown off from each different cell or unit throughout the body must be inconceivably numerous and minute. Each unit of each part, as it changes during development--and we know that some insects undergo at least twenty {210} metamorphoses--must throw off its gemmules. All organic beings, moreover, include many dormant gemmules derived from their grandparents and more remote progenitors, but not from all their progenitors. These _almost infinitely numerous_ and minute gemmules must be included in each bud, ovule, spermatozoon, and pollen grain." We have seen also that in certain cases a similar multitude of gemmules must be included also in every considerable part of the whole body of each organism, but where are we to stop? There must be gemmules not only from every organ, but from every component part of such organ, from every subdivision of such component part, and from every cell, thread, or fibre entering into the composition of such subdivision. Moreover, not only from all these, but from each and every successive stage of the evolution and development of such successively more and more elementary parts. At the first glance this new atomic theory has charms from its apparent simplicity, but the attempt thus to follow it out into its ultimate limits and extreme consequences seems to indicate that it is at once insufficient and cumbrous. Mr. Darwin himself is, of course, fully aware that there must be _some_ limit to this aggregation of gemmules. He says:[220] "Excessively minute and numerous as they are believed to be, an infinite number derived, during a long course of modification and descent, from each cell of each progenitor, could not be supported and nourished by the organism." But apart from these matters, which will be more fully considered further on, the hypothesis not only does not appear to account for certain phenomena which, in order to be a valid theory, it ought to account for; but it seems absolutely to conflict with patent and notorious facts. How, for example, does it explain the peculiar reproduction which is {211} found to take place in certain marine worms--certain annelids? [Illustration: AN ANNELID DIVIDING SPONTANEOUSLY. (A new head having been formed towards the hinder end of the body of the parent.)] In such creatures we see that, from time to time, one of the segments of the body gradually becomes modified till it assumes the condition of a head, and this remarkable phenomenon is repeated again and again, the body of the worm thus multiplying serially into new individuals which successively detach themselves from the older portion. The development of such a mode of reproduction by "Natural Selection" seems not less inexplicable than does its continued performance through the aid of {212} "pangenesis." For how can gemmules attach themselves to others to which they do not normally or generally succeed? Scarcely less difficult to understand is the process of the stomach-carrying-off mode of metamorphosis before spoken of as existing in the Echinoderms. Next, as to certain patent and notorious facts: On the hypothesis of pangenesis, no creature can develop an organ unless it possesses the component gemmules which serve for its formation. No creature can possess such gemmules unless it inherits them from its parents, grandparents, or its less remote ancestors. Now, the Jews are remarkably scrupulous as to marriage, and rarely contract such a union with individuals not of their own race. This practice has gone on for thousands of years, and similarly also for thousands of years the rite of circumcision has been unfailingly and carefully performed. If then the hypothesis of pangenesis is well founded, that rite ought to be now absolutely or nearly superfluous from the necessarily continuous absence of certain gemmules through so many centuries and so many generations. Yet it is not at all so, and this fact seems to amount almost to an experimental demonstration that the hypothesis of pangenesis is an insufficient explanation of individual evolution. Two exceedingly good criticisms of Mr. Darwin's hypothesis have appeared. One of these is by Mr. G. H. Lewes,[221] the other by Professor Delpino of Florence.[222] The latter gentleman gives a report of an observation made by him upon a certain plant, which observation adds force to what has just been said about the Jewish race. He says:[223] "If we examine and compare the numerous species of the genus _Salvia_, commencing with _Salvia officinalis_, which may pass as the main state of the genus, and {213} concluding with _Salvia verticillata_, which may be taken as the most highly developed form, and as the most distant from the type, we observe a singular phenomenon. The lower cell of each of the two fertile anthers, which is much reduced and different from the superior even in _Salvia officinalis_, is transmuted in other _salviæ_ into an organ (nectarotheca) having a very different form and function, and finally disappears entirely in _Salvia verticillata_. "Now, on one occasion, in a flower belonging to an individual of _Salvia verticillata_, and only on the left stamen, I observed a perfectly developed and pollinigerous lower cell, perfectly homologous with that which is normally developed in _Salvia officinalis_. This case of atavism is truly singular. According to the theory of Pangenesis, it is necessary to assume that all the gemmules of this anomalous formation, and therefore the mother-gemmule of the cell, and the daughter-gemmules of the special epidermic tissue, and of the very singular subjacent tissue of the endothecium, have been perpetuated, and transmitted from parent to offspring in a dormant state, and through a number of generations, such as startles the imagination, and leads it to refuse its consent to the theory of Pangenesis, however seductive it may be." This seems a strong confirmation of what has been here advanced. The main objection raised against Mr. Darwin's hypothesis is that it (Pangenesis) requires so many subordinate hypotheses for its support, and that some of these are not tenable. Professor Delpino considers[224] that as many as eight of these subordinate hypotheses are required, namely, that-- "1. The emission of the gemmules takes place, or may take place in all states of the cell. "2. The quantity of gemmules emitted from every cell is very great. "3. The minuteness of the gemmules is extreme. {214} "4. The gemmules possess two sorts of affinity, one of which might be called _propagative_, and the other _germinative_ affinity. "5. By means of the propagative affinity all the gemmules emitted by all the cells of the individual flow together and become condensed in the cells which compose the sexual organs, whether male or female (embryonal vesicle, cells of the embryo, pollen grains, fovilla, antherozoids, spermatozoids), and likewise flow together and become condensed in the cells which constitute the organs of a sexual or agamic reproduction (buds, spores, bulbilli, portions of the body separated by scission, &c.). "6. By means of the germinative affinity, every gemmule (except in cases of anomalies or monstrosities) can be developed only in cells homologous with the mother-cells of the cell from which they originated. In other words, the gemmules from any cell can only be developed in unison with the cell preceding it in due order of succession, and whilst in a nascent state. "7. Of each kind of gernmule a great number perishes; a great number remains in a dormant state through many generations in the bodies of descendants; the remainder germinate and reproduce the mother-cell. "8. Every gemmule may multiply itself by a process of scission into any number of equivalent gemmules." Mr. Darwin has published a short notice in reply to Professor Delpino, in _Scientific Opinion_ of October 20, 1869, p. 426. In this reply he admits the justice of Professor Delpino's attack, but objects to the alleged necessity of the first subordinate hypothesis, namely, that the emission of gemmules takes place in all states of the cell. But if this is not the case, then a great part of the utility and distinction of pangenesis is destroyed, or as Mr. Lewes justly says,[225] "If gemmules produce whole cells, we have the very power which was pronounced mysterious in larger organisms." {215} Mr. Darwin also does not see the force of the objection to the power of self-division which must be asserted of the gemmules themselves if Pangenesis be true. The objection, however, appears to many to be formidable. To admit the power of spontaneous division and multiplication in such rudimentary structures, seems a complete contradiction. The gemmules, by the hypothesis of Pangenesis, are the ultimate organized components of the body, the absolute organic atoms of which each body is composed; how then _can_ they be divisible? Any part of a gemmule would be an impossible (because a _less_ than possible) quantity. If it is divisible into still smaller organic wholes, as a germ-cell is, it must be made up as the germ-cell is, of subordinate component atoms, which are then the _true_ gemmules. This process may be repeated _ad infinitum_, unless we get to true organic atoms, the true gemmules, whatever they may be, and they necessarily will be incapable of any process of spontaneous fission. It is remarkable that Mr. Darwin brings forward in support of gemmule fission, the observation that "Thuret has seen the zoospore of an alga divide itself, and both halves germinate." Yet on the hypothesis of Pangenesis, the zoospore of an alga must contain gemmules from all the cells of the parent algæ, and from all the parts of all their less remote ancestors in all their stages of existence. What wonder then that such an excessively complex body should divide and multiply; and what parity is there between such a body and a gemmule? A steam-engine and a steel-filing might equally well be compared together. Professor Delpino makes a further objection which, however, will only be of weight in the eyes of Vitalists. He says,[226] Pangenesis is not to be received because "it leads directly to the negation of a specific vital principle, co-ordinating and regulating all the movements, acts, and functions of the individuals in which it is incarnated. For Pangenesis of the individual is a term without meaning. If, in contemplating an {216} animal of high organization, we regard it purely as an aggregation of developed gemmules, although these gemmules have been evolved successively one after the other, and one within the other, notwithstanding they elude the conception of the _real and true individual_, these problematical and invisible gemmules must be regarded as so many individuals. Now, that real, true, living individuals exist in nature, is a truth which is persistently attested to us by our consciousness. But how, then, can we explain that a great quantity of dissimilar elements, like the atoms of matter, can unite to form those perfect unities which we call individuals, if we do not suppose the existence of a specific principle, proper to the individual but foreign to the component atoms, which aggregates these said atoms, groups them into molecules, and then moulds the molecules into cells, the cells into tissues, the tissues into organs, and the organs into apparatus?" "But, it may be urged in opposition by the Pangenesists, your vital principle is an unknown and irresolute _x_. This is true; but, on the other hand, let us see whether Pangenesis produces a clearer formula, and one free from unknown elements. The existence of the gemmules is a first unknown element; the propagative affinity of the gemmules is a second; their germinative affinity is a third; their multiplication by fission is a fourth--and what an unknown element!" "Thus, in Pangenesis, everything proceeds by force of unknown elements, and we may ask whether it is more logical to prefer a system which assumes a multitude of unknown elements to a system which assumes only a single one?" Mr. Darwin appears, by "Natural Selection," to destroy the reality of species, and by Pangenesis that of the individual. Mr. Lewes observes[227] of the individual that "This whole is only a subjective conception which summarizes the parts, and that in point of fact it is the parts which {217} are reproduced." But the parts are also, from the same point of view, merely subjective until we come to the absolute organic atoms. These atoms, on the other hand, are utterly invisible, intangible; indeed, in the words of Mr. Darwin, inconceivable. Thus, then, it results from the theories in question, that the organic world is reduced to utter unreality as regards all that can be perceived by the senses or distinctly imagined by the mind; while the only reality consists of the invisible, the insensible, the inconceivable; in other words, nothing is known that really is, and only the nonexistent can be known. A somewhat paradoxical outcome of the speculations of those who profess to rely exclusively on the testimony of sense. "_Les extrêmes se touchent_," and extreme sensationalism shakes hands with the "das seyn ist das nichts" of Hegel. Altogether the hypothesis of Pangenesis seems to be little, if at all, superior to anterior hypotheses of a more or less similar nature. Apart from the atoms of Democritus, and apart also from the speculations of mediæval writers, the molecules of Bonnet and of Buffon almost anticipated the hypothesis of Pangenesis. According to the last-named author,[228] organic particles from every part of the body assemble in the sexual secretions, and by their union build up the embryo, each particle taking its due place, and occupying in the offspring a similar position to that which it occupied in the parents. In 1849 Professor Owen, in his treatise on "Parthenogenesis," put forward another conception. According to this, the cells resulting from the subdivision of the germ-cell preserve their developmental force, unless employed in building up definite organic structures. In certain creatures, and in certain parts of other creatures, germ-cells unused are stored up, and by their agency lost limbs and {218} other mutilations are repaired. Such unused products of the germ-cell are also supposed to become located in the generative products. According to Mr. Herbert Spencer, in his "Principles of Biology," each living organism consists of certain so-called "physiological units." Each of these units has an innate power and capacity, by which it tends to build up and reproduce the entire organism of which it forms a part, unless in the meantime its force is exhausted by its taking part in the production of some distinct and definite tissue--a condition somewhat similar to that conceived by Professor Owen. Now, at first sight, Mr. Darwin's atomic theory appears to be more simple than any of the others. It has been objected that while Mr. Spencer's theory requires the assumption of an innate power and tendency in each physiological unit, Mr. Darwin's, on the other hand, requires nothing of the kind, but explains the evolution of each individual by purely mechanical conceptions. In fact, however, it is not so. Each gemmule, according to Mr. Darwin, is really the seat of powers, elective affinities, and special tendencies as marked and mysterious as those possessed by the physiological unit of Mr. Spencer, with the single exception that the former has no tendency to build up the whole living, complex organism of which it forms a part. Some may think this an important distinction, but it can hardly be so, for Mr. Darwin considers that his gemmule has the innate power and tendency to build up and transform itself into the whole living, complex cell of which it forms a part; and the one tendency is, in principle, fully as difficult to understand, fully as mysterious, as is the other. The difference is but one of degree, not of kind. Moreover, the one mystery in the case of the "physiological unit" explains all, while with regard to the gemmule, as we have seen, it has to be supplemented by other powers and tendencies, each distinct, and each in itself inexplicable and profoundly mysterious. [Page 219] That there should be physiological units possessed of the power attributed to them, harmonizes with what has recently been put forward by Dr. H. Charlton Bastian; who maintains that under fit conditions the simplest organisms develop themselves into relatively large and complex ones. This is not supposed by him to be due to any inheritance of ancestral gemmules, but to direct growth and transformation of the most minute and the simplest organisms, which themselves, by all reason and analogy, owe their existence to immediate transformation from the inorganic world. Thus, then, there are grave difficulties in the way of the reception of the hypothesis of Pangenesis, which moreover, if established, would leave the evolution of individual organisms, when thoroughly analysed, little if at all less mysterious or really explicable than it is at present. As was said at the beginning of this chapter, "Pangenesis" and "Natural Selection" are quite separable and distinct hypotheses. The fall of one of these by no means necessarily includes that of the other. Nevertheless, Mr. Darwin has associated them closely together, and, therefore, the refutation of Pangenesis may render it advisable for those who have hitherto accepted "Natural Selection" to reconsider that theory. [Page 220] * * * * * CHAPTER XI. SPECIFIC GENESIS. Review of the statements and arguments of preceding chapters.--Cumulative argument against predominant action of "Natural Selection."--Whether anything positive as well as negative can be enunciated.--Constancy of laws of nature does not necessarily imply constancy of specific evolution.--Possible exceptional stability of existing epoch.--Probability that an internal cause of change exists.--Innate powers must be conceived as existing somewhere or other.--Symbolism of molecular action under vibrating impulses.--Professor Owen's statement.--Statement of the Author's view.--It avoids the difficulties which oppose "Natural Selection."--It harmonizes apparently conflicting conceptions.--Summary and conclusion. Having now severally reviewed the principal biological facts which bear upon specific manifestation, it remains to sum up the results, and to endeavour to ascertain what, if anything, can be said _positively_, as well as negatively, on this deeply interesting question. In the preceding chapters it has been contended, in the first place, that no mere survival of the fittest accidental and minute variations can account for the incipient stages of useful structures, such as, _e.g._, the heads of flat-fishes, the baleen of whales, vertebrate limbs, the laryngeal structures of the newborn kangaroo, the pedicellariæ of Echinoderms, or for many of the facts of mimicry, and especially those last touches of mimetic perfection, where an insect not only mimics a leaf, but one worm-eaten and attacked by fungi. [Page 221] Also, that structures like the hood of the cobra and the rattle of the rattlesnake seem to require another explanation. Again, it has been contended that instances of colour, as in some apes; of beauty, as in some shell-fish; and of utility, as in many orchids, are examples of conditions which are quite beyond the power of Natural Selection to originate and develop. Next, the peculiar mode of origin of the eye (by the simultaneous and concurrent modification of distinct parts), with the wonderful refinement of the human ear and voice, have been insisted on; as also, that the importance of all these facts is intensified through the necessity (admitted by Mr. Darwin) that many individuals should be similarly and simultaneously modified in order that slightly favourable variations may hold their own in the struggle for life, against the overwhelming force and influence of mere number. Again, we have considered, in the third chapter, the great improbability that from minute variations in all directions alone and unaided, save by the survival of the fittest, closely similar structures should independently arise; though, on a non-Darwinian evolutionary hypothesis, their development might be expected _a priori_. We have seen, however, that there are many instances of wonderfully close similarity which are not due to genetic affinity; the most notable instance, perhaps, being that brought forward by Mr. Murphy, namely, the appearance of the same eye-structure in the vertebrate and molluscous sub-kingdoms. A curious resemblance, though less in degree, has also been seen to exist between the auditory organs of fishes and of Cephalopods. Remarkable similarities between certain placental and implacental mammals, between the bird's-head processes of Polyzoa and the pedicellariæ of Echinoderms, between Ichthyosauria and Cetacea, with very many other similar coincidences, have also been pointed out. Evidence has also been brought forward to show that similarity is sometimes directly induced by very obscure conditions, at present quite {222} inexplicable, _e.g._ by causes immediately connected with geographical distribution; as in the loss of the tail in certain forms of Lepidoptera and in simultaneous modifications of colour in others, and in the direct modification of young English oysters, when transported to the shore of the Mediterranean. Again, it has been asserted that certain groups of organic forms seem to have an innate tendency to remarkable developments of some particular kind, as beauty and singularity of plumage in the group of birds of paradise. It has also been contended that there is something to be said in favour of sudden, as opposed to exceedingly minute and gradual, modifications, even if the latter are not fortuitous. Cases were brought forward, in Chapter IV., such as the bivalve just mentioned, twenty-seven kinds of American trees simultaneously and similarly modified, also the independent production of pony breeds, and the case of the English greyhounds in Mexico, the offspring of which produced directly acclimated progeny. Besides these, the case of the Normandy pigs, of _Datura tatula_, and also of the black-shouldered peacock, have been spoken of. The teeth of the labyrinthodon, the hand of the potto, the whalebone of whales, the wings of birds, the climbing tendrils of some plants, &c. have also been adduced as instances of structures, the origin and production of which are probably due rather to considerable modifications than to minute increments. It has also been shown that certain forms which were once supposed to be especially transitional and intermediate (as, _e.g._, the aye-aye) are really by no means so; while the general rule, that the progress of forms has been "from the more general to the more special," has been shown to present remarkable exceptions, as, _e.g._, Macrauchenia, the Glyptodon, and the sabre-toothed tiger (Machairodus). Next, as to specific stability, it has been seen that there may be a {223} certain limit to normal variability, and that if changes take place they may be expected _a priori_ to be marked and considerable ones, from the facts of the inorganic world, and perhaps also of the lowest forms of the organic world. It has also been seen that with regard to minute spontaneous variations in races, there is a rapidly increasing difficulty in intensifying them, in any one direction, by ever such careful breeding. Moreover, it has appeared that different species show a tendency to variability in special directions, and probably in different degrees, and that at any rate Mr. Darwin himself concedes the existence of an internal barrier to change when he credits the goose with "a singularly inflexible organization;" also, that he admits the presence of an _internal_ proclivity to change when he speaks of "a whole organization seeming to have become plastic, and tending to depart from the parental type." We have seen also that a marked tendency to reversion does exist, inasmuch as it sometimes takes place in a striking manner, as exemplified in the white silk fowl in England, _in spite of_ careful selection in breeding. Again, we have seen that a tendency exists in nature to eliminate hybrid races, by whatever means that elimination is effected, while no similar tendency bars the way to an indefinite blending of varieties. This has also been enforced by statements as to the prepotency of certain pollen of identical species, but of distinct races. To all the preceding considerations have been added others derived from the relations of species to past time. It has been contended that we have as yet no evidence of minutely intermediate forms connecting uninterruptedly together undoubtedly distinct species. That while even "horse ancestry" fails to supply such a desideratum, in very strongly marked and exceptional kinds (such as the Ichthyosauria, Chelonia, and Anoura), the absence of links is very important and significant. For if every species, without{224} exception, has arisen by minute modifications, it seems incredible that a small percentage of such transitional forms should not have been preserved. This, of course, is especially the case as regards the marine Ichthyosauria and Plesiosauria, of which such numbers of remains have been discovered. Sir William Thomson's great authority has been seen to oppose itself to "Natural Selection," by limiting, on astronomical and physical grounds, the duration of life on this planet to about one hundred million years. This period, it has been contended, is not nearly enough on the one hand for the evolution of all organic forms by the exclusive action of mere minute, fortuitous variations; on the other hand, for the deposition of all the strata which must have been deposited, if minute fortuitous variation was the manner of successive specific manifestation. Again, the geographical distribution of existing animals has been seen to present difficulties which, though not themselves insurmountable, yet have a certain weight when taken in conjunction with all the other objections. The facts of homology, serial, bilateral and vertical, have also been passed in review. Such facts, it has been contended, are not explicable without admitting the action of what may most conveniently be spoken of as an _internal_ power, the existence of which is supported by facts not only of comparative anatomy but of teratology and pathology also. "Natural Selection" also has been shown to be impotent to explain these phenomena, while the existence of such an internal power of homologous evolution diminishes the _a priori_ improbability of an analogous law of specific origination. All these various considerations have been supplemented by an endeavour to show the utter inadequacy of Mr. Darwin's theory with regard to the higher psychical phenomena of man (especially the evolution of moral conceptions), and with regard to the evolution of individual organisms by the action{225} of Pangenesis. And it was implied that if Mr. Darwin's latter hypothesis can be shown to be untenable, an antecedent doubt is thus thrown upon his other conception, namely, the theory of "Natural Selection." A cumulative argument thus arises against the prevalent action of "Natural Selection," which, to the mind of the Author, is conclusive. As before observed, he was not originally disposed to reject Mr. Darwin's fascinating theory. Reiterate endeavours to solve its difficulties have, however, had the effect of convincing him that that theory as the one or as the leading explanation of the successive evolution and manifestation of specific forms, is untenable. At the same time he admits fully that "Natural Selection" acts and must act, and that it plays in the organic world a certain though a secondary and subordinate part. The one _modus operandi_ yet suggested having been found insufficient, the question arises, Can another be substituted in its place? If not, can anything that is positive, and if anything, what, be said as to the question of specific origination? Now, in the first place, it is of course axiomatic that the laws which conditioned the evolution of extinct and of existing species are of as much efficacy at this moment as at any preceding period, that they _tend_ to the manifestation of new forms as much now as ever before. It by no means necessarily follows, however, that this tendency is actually being carried into effect, and that new species of the higher animals and plants are actually now produced. They may be so or they may not, according as existing circumstances favour, or conflict with, the action of those laws. It is possible that lowly organized creatures may be continually evolved at the present day, the requisite conditions being more or less easily supplied. There is, however, no similar evidence at present as to higher forms; while, as we have seen in Chapter VII., there are _a priori_ considerations which militate against their being similarly evolved. {226} The presence of wild varieties and the difficulty which often exists in the determination of species are sometimes adduced as arguments that high forms are now in process of evolution. These facts, however, do not necessarily prove more than that some species possess a greater variability than others, and (what is indeed unquestionable) that species have often been unduly multiplied by geologists and botanists. It may be, for example, that Wagner was right, and that all the American monkeys of the genus cebus may be reduced to a single species or to two. With regard to the lower organisms, and supposing views recently advanced to become fully established, there is no reason to think that the forms said to be evolved were new species, but rather reappearances of definite kinds which had appeared before and will appear again under the same conditions. In the same way, with higher forms similar conditions must educe similar results, but here practically similar conditions can rarely obtain because of the large part which "descent" and "inheritance" always play in such highly organized forms. Still it is conceivable that different combinations at different times may have occasionally the same outcome just as the multiplications of different numbers may have severally the same result. There are reasons, however, for thinking it possible that the human race is a witness of an exceptionally unchanging and stable condition of things, if the calculations of Mr. Croll are valid as to how far variations in the eccentricity in the earth's orbit together with the precession of the equinoxes have produced changes in climate. Mr. Wallace has pointed out[229] that the last 60,000 years having been exceptionally unchanging as regards these conditions, specific evolution may have been {227} exceptionally rare. It becomes then possible to suppose that for a similar period stimuli to change in the manifestation of animal forms may have been exceptionally few and feeble,--that is, if the conditions of the earth's orbit have been as exceptional as stated. However, even if new species are actually now being evolved as actively as ever, or if they have been so quite recently, no conflict thence necessarily arises with the view here advocated. For it by no means follows that if some examples of new species have recently been suddenly produced from individuals of antecedent species, we ought to be able to put our fingers on such cases; as Mr. Murphy well observes[230] in a passage before quoted, "If a species were to come suddenly into being in the wild state, as the Ancon sheep did under domestication, how could we ascertain the fact? If the first of a newly-born species were found, the fact of its discovery would tell nothing about its origin. Naturalists would register it as a very rare species, having been only once met with, but they would have no means of knowing whether it were the first or the last of its race." But are there any grounds for thinking that in the genesis of species an _internal_ force or tendency interferes, co-operates with and controls the action of external conditions? It is here contended that there are such grounds, and that though inheritance, reversion, atavism, Natural Selection, &c., play a part not unimportant, yet that such an internal power is a great, perhaps the main, determining agent. It will, however, be replied that such an entity is no _vera causa_; that if the conception is accepted, it is no real explanation; and that it is merely a roundabout way of saying that the facts are as they are, while the cause remains unknown. To this it may be rejoined that for all who believe in the existence of the abstraction "force" at all, other than will, {228} this conception of an internal force must be accepted and located somewhere--cannot be eliminated altogether; and that therefore it may as reasonably be accepted in this mode as in any other. It was urged at the end of the third chapter that it is congruous to credit mineral species with an internal power or force. By such a power it may be conceived that crystals not only assume their external symmetry, but even repair it when injured. Ultimate chemical elements must also be conceived as possessing an innate tendency to form certain unions, and to cohere in stable aggregations. This was considered towards the end of Chapter VIII. Turning to the organic world, even on the hypothesis of Mr. Herbert Spencer or that of Mr. Darwin, it is impossible to escape the conception of innate internal forces. With regard to the physiological units of the former, Mr. Spencer himself, as we have seen, distinctly attributes to them "an _innate_ tendency" to evolve the parent form from which they sprang. With regard to the gemmules of Mr. Darwin, we have seen, in Chapter X., with how many innate powers, tendencies, and capabilities they must each be severally endowed, to reproduce their kind, to evolve complex organisms or cells, to exercise germinative affinity, &c. If then (as was before said at the end of Chapter VIII.) such innate powers must be attributed to chemical atoms, to mineral species, to gemmules, and to physiological units, it is only reasonable to attribute such to each individual organism. The conception of such internal and latent capabilities is somewhat like that of Mr. Galton, before mentioned, according to which the organic world consists of entities, each of which is, as it were, a spheroid with many facets on its surface, upon one of which it reposes in stable equilibrium. When by the accumulated action of incident forces this equilibrium is {229} disturbed, the spheroid is supposed to turn over until it settles on an adjacent facet once more in stable equilibrium. The internal tendency of an organism to certain considerable and definite changes would correspond to the facets on the surface of the spheroid. It may be objected that we have no knowledge as to how terrestrial, cosmical and other forces can affect organisms so as to stimulate and evolve these latent, merely potential forms. But we have had evidence that such mysterious agencies _do_ affect organisms in ways as yet inexplicable, in the very remarkable effects of geographical conditions which were detailed in the third chapter. It is quite conceivable that the material organic world may be so constituted that the simultaneous action upon it of all known forces, mechanical, physical, chemical, magnetic, terrestrial, and cosmical, together with other as yet unknown forces which probably exist, may result in changes which are harmonious and symmetrical, just as the internal nature of vibrating plates causes particles of sand scattered over them to assume definite and symmetrical figures when made to oscillate in different ways by the bow of a violin being drawn along their edges. The results of these combined internal powers and external influences might be represented under the symbol of complex series of vibrations (analogous to those of sound or light) forming a most complex harmony or a display of most varied colours. In such a way the reparation of local injuries might be symbolized as a filling up and completion of an interrupted rhythm. Thus also monstrous aberrations from typical structure might correspond to a discord, and sterility from crossing be compared with the darkness resulting from the interference of waves of light. Such symbolism will harmonize with the peculiar reproduction, before mentioned, of heads in the body of certain annelids, with the facts of serial homology, as well as those of bilateral and vertical symmetry. {230} Also, as the atoms of a resonant body may be made to give out sound by the juxtaposition of a vibrating tuning-fork, so it is conceivable that the physiological units of a living organism may be so influenced by surrounding conditions (organic and other) that the accumulation of these conditions may upset the previous rhythm of such units, producing modifications in them--a fresh chord in the harmony of nature--a new species! But it may be again objected that to say that species arise by the help of an innate power possessed by organisms is no explanation, but is a reproduction of the absurdity, _l'opium endormit parcequ'il a une vertu soporifique_. It is contended, however, that this objection does not apply, even if it be conceded that there is that force in Molière's ridicule which is generally attributed to it.[231] Much, however, might be said in opposition to more than one of that brilliant dramatist's smart philosophical epigrams, just as to the theological ones of Voltaire, or to the biological one of that other Frenchman who for a time discredited a cranial skeletal theory by the phrase "Vertèbre pensante."[232] In fact, however, it is a real explanation of how a man lives to say that he lives independently, on his own income, instead of being supported by his relatives and friends. In the same way, there is fully as real a distinction between the production of new specific manifestations entirely _ab externo_, and by the production of the same through an innate force and tendency, the determination of which into action is occasioned by {231} external circumstances. To say that organisms possess this innate power, and that by it new species are from time to time produced, is by no means a mere assertion that they _are_ produced, and in an unknown mode. It is the negation of that view which deems external forces alone sufficient, and at the same time the assertion of something positive, to be arrived at by the process of _reductio ad absurdum_. All physical explanations result ultimately in such conceptions of innate power, or else in that of will force. The far-famed explanation of the celestial motions ends in the conception that every particle of matter has the innate power of attracting every other particle directly as the mass, and inversely as the square of the distance. We are logically driven to this positive conception if we do not accept the view that there is no force but volition, and that all phenomena whatever are the immediate results of the action of intelligent and self-conscious will. We have seen that the notion of sudden changes--saltatory actions in nature--has received countenance from Professor Huxley.[233] We must conceive that these jumps are orderly, and according to law, inasmuch as the whole cosmos is such. Such orderly evolution harmonizes with a teleology derived, not indeed from external nature directly, but from the mind of man. On this point, however, more will be said in the next chapter. But, once more, if new species are not manifested by the action of external conditions upon minute indefinite individual differences, in what precise way may we conceive that manifestation to have taken place? Are new species now evolving, as they have been from time to time evolved? If so, in what way and by what conceivable means? {232} In the first place, they must be produced by natural action in pre-existing material, or by supernatural action. For reasons to be given in the next chapter, the second hypothesis need not be considered. If, then, new species are and have been evolved from pre-existing material, must that material have been organic or inorganic? As before said, additional arguments have lately been brought forward to show that individual organisms _do_ arise from a basis of _in_-organic material only. As, however, this at the most appears to be the case, if at all, only with the lowest and most minute organisms exclusively, the process cannot be observed, though it may perhaps be fairly inferred. We may therefore, if for no other reason, dismiss the notion that highly organized animals and plants can be suddenly or gradually built up by any combination of physical forces and natural powers acting externally and internally upon and in merely inorganic material as a base. But the question is, how have the highest kinds of animals and plants arisen? It seems impossible that they can have appeared otherwise than by the agency of antecedent organisms not greatly different from them. A multitude of facts, ever increasing in number and importance, all point to such a mode of specific manifestation. One very good example has been adduced by Professor Flower in the introductory lecture of his first Hunterian Course.[234] It is the reduction in size, to a greater or less degree, of the second and third digits of the foot in Australian marsupials, and this, in spite of the very different form and function of the foot in different groups of those animals. A similarly significant evidence of relationship is afforded by processes of the zygomatic region of the skull in certain edentates existing and extinct. {233} Again, the relation between existing and recent faunas of the different regions of the world, and the predominating (though by no means exclusive) march of organization, from the more general to the more special, point in the same direction. Almost all the facts brought forward by the patient industry of Mr. Darwin in support of his theory of "Natural Selection," are of course available as evidence in favour of the agency of pre-existing and similar animals in specific evolution. Now the new forms must be produced by changes taking place in organisms in, after or before their birth, either in their embryonic, or towards or in their adult, condition. Examples of strange births are sufficiently common, and they may arise either from direct embryonic modifications or apparently from some obscure change in the parental action. To the former category belong the hosts of instances of malformation through arrest of development, and perhaps generally monstrosities of some sort are the result of such affections of the embryo. To the second category belong all cases of hybridism, of cross breed, and in all probability the new varieties and forms, such as the memorable one of the black-shouldered peacock. In all these cases we do not have abortions or monstrosities, but more or less harmonious forms often of great functional activity, endowed with marked viability and generative prepotency, except in the case of hybrids, when we often find even a more marked generative impotency. It seems probable therefore that new species may arise from some constitutional affection of parental forms--an affection mainly, if not exclusively, of their generative system. Mr. Darwin has carefully collected[235] numerous instances to show how excessively sensitive to various influences this system is. He says:[236] "Sterility is independent of general health, and is often accompanied by excess of size, or {234} great luxuriance," and, "No one can tell, till he tries; whether any particular animal will breed under confinement, or any exotic plant seed freely under culture." Again, "When a new character arises, whatever its nature may be, it generally tends to be inherited, at least in a temporary and sometimes in a most persistent manner."[237] Yet the obscure action of conditions will alter characters long inherited, as the grandchildren of Aylesbury ducks, removed to a distant part of England, completely lost their early habit of incubation, and hatched their eggs at the same time with the common ducks of the same place.[238] Mr. Darwin quotes Mr. Bartlett as saying: "It is remarkable that lions breed more freely in travelling collections than in the zoological gardens; probably the constant excitement and irritation produced by moving from place to place, or change of air, may have considerable influence in the matter."[239] Mr. Darwin also says: "There is reason to believe that insects are affected by confinement like the higher animals," and he gives examples.[240] Again, he gives examples of change of plumage in the linnet, bunting, oriole, and other birds, and of the temporary modification of the horns of a male deer during a voyage.[241] Finally, he adds that these changes cannot be attributed to loss of health or vigour, "when we reflect how healthy, long-lived, and vigorous many animals are under captivity, such as parrots, and hawks when used for hawking, chetahs when used for hunting, and elephants. The reproductive organs themselves are not diseased; and the diseases from which animals in menageries usually perish, are not those which in any way affect their fertility. No domestic animal is more subject to disease than the sheep, yet it is remarkably prolific.... It would appear that any change in {235} the habits of life, whatever these habits may be, if great enough, tends to affect in an inexplicable manner the powers of reproduction." Such, then, is the singular sensitiveness of the generative system. As to the means by which that system is affected, we see that a variety of conditions affect it; but as to the modes in which they act upon it, we have as yet little if any clue. We have also seen the singular effects (in tailed Lepidoptera, &c.) of causes connected with geographical distribution, the mode of action of which is as yet quite inexplicable; and we have also seen the innate tendency which there appears to be in certain groups (birds of paradise, &c.) to develop peculiarities of a special kind. It is, to say the least, probable that other influences exist, terrestrial and cosmical, as yet un-noted. The gradually accumulating or diversely combining actions of all these on highly sensitive structures, which are themselves possessed of internal responsive powers and tendencies, may well result in occasional repeated productions of forms harmonious and vigorous, and differing from the parental forms in proportion to the result of the combining or conflicting action of all external and internal influences. If, in the past history of this planet, more causes ever intervened, or intervened more energetically than at present, we might _a priori_ expect a richer and more various evolution of forms more radically differing than any which could be produced under conditions of more perfect equilibrium. At the same time, if it be true that the last few thousand years have been a period of remarkable and exceptional uniformity as regards this planet's astronomical relations, there are then some grounds for thinking that organic evolution may have been exceptionally depressed during the same epoch. Now, as to the fact that sudden changes and sudden developments have {236} occurred, and as to the probability that such changes are likely to occur, evidence was given in Chapter IV. In Chapter V. we also saw that minerals become modified suddenly and considerably by the action of incident forces--as, _e.g._, the production of hexagonal tabular crystals of carbonate of copper by sulphuric acid, and of long rectangular prisms by ammonia, &c. We have thus a certain antecedent probability that if changes are produced in specific manifestation through incident forces, these changes will be sensible and considerable, not minute and infinitesimal. Consequently, it is probable that new species have appeared from time to time with comparative suddenness, and that they still continue so to arise if all the conditions necessary for specific evolution now obtain. This probability will be increased if the observations of Dr. Bastian are confirmed by future investigation. According to his report, when the requisite conditions were supplied, the transformations which appeared to take place (from very low to higher organisms) were sudden, definite, and complete. Therefore, if this is so, there must probably exist in higher forms a similar tendency to such change. That tendency may indeed be long suppressed, and ultimately modified by the action of heredity--an action which would increase in force with the increase in the perfection and complexity of the organism affected. Still we might expect that such changes as do take place would be also sudden, definite, and complete. Moreover, as the same causes produce the same effects, several individual parent forms must often have been similarly and simultaneously affected. That they should be so affected--at least that several similarly modified individuals should simultaneously arise--has been seen to be a generally necessary circumstance for the permanent duration of such new modifications. It is also conceivable that such new forms may be endowed with {237} excessive constitutional strength and viability, and with generative prepotency, as was the case with the black-shouldered peacock in Sir J. Trevelyan's flock. This flock was entirely composed of the common kind, and yet the new form rapidly developed itself "_to the extinction of the previously existing breed_."[242] Indeed, the notion accepted by both Mr. Darwin and Mr. Herbert Spencer, and which is plainly the fact (namely, that changes of conditions and incident forces, within limits, augment the viability and fertility of individuals), harmonizes well with the suggested possibility as to an augmented viability and prepotency in new organic forms evolved by peculiar consentaneous actions of conditions and forces, both external and internal. The remarkable series of changes noted by Dr. Bastian were certainly not produced by external incident forces _only_, but by these acting on a peculiar _materia_, having special properties and powers. Therefore, the changes were induced by the consentaneous action of internal and external forces.[243] In the same way then, we may expect changes in higher forms to be evolved by similar united action of internal and external forces. One other point may here be alluded to. When the remarkable way in which structure and function simultaneously change, is borne in mind; when those numerous instances in which nature has supplied similar wants by similar means, as detailed in Chapter III., are remembered; when also all the wonderful contrivances of orchids, of mimicry, and the strange complexity of certain instinctive actions are considered: then the conviction forces itself on many minds that the organic world is the expression of an intelligence of some kind. This view has been well advocated by Mr. Joseph John Murphy, in his recent work so often here referred to. {238} This intelligence, however, is evidently not altogether such as ours, or else has other ends in view than those most obvious to us. For the end is often attained in singularly roundabout ways, or with a prodigality of means which seems out of all proportion with the result: not with the simple action directed to one end which generally marks human activity. Organic nature then speaks clearly to many minds of the action of an intelligence resulting, on the whole and in the main, in order, harmony, and beauty, yet of an intelligence the ways of which are not such as ours. This view of evolution harmonizes well with Theistic conceptions; not, of course, that this harmony is brought forward as an argument in its favour generally, but it will have weight with those who are convinced that Theism reposes upon solid grounds of reason as _the_ rational view of the universe. To such it may be observed that, thus conceived, the Divine action has that slight amount of resemblance to, and that wide amount of divergence from what human action would be, which might be expected _a priori_--might be expected, that is, from a Being whose nature and aims are utterly beyond our power to imagine, however faintly, but whose truth and goodness are the fountain and source of our own perceptions of such qualities. The view of evolution maintained in this work, though arrived at in complete independence, yet seems to agree in many respects with the views advocated by Professor Owen in the last volume of his "Anatomy of Vertebrates," under the term "derivation." He says:[244] "Derivation holds that every species changes in time, by virtue of inherent tendencies thereto. 'Natural Selection' holds that no such change can take place without the influence of altered external circumstances.[245] {239} 'Derivation' sees among the effects of the innate tendency to change irrespective of altered circumstances, a manifestation of creative power in the variety and beauty of the results; and, in the ultimate forthcoming of a being susceptible of appreciating such beauty, evidence of the pre-ordaining of such relation of power to the appreciation. 'Natural Selection' acknowledges that if ornament or beauty, in itself, should be a purpose in creation, it would be absolutely fatal to it as a hypothesis." "'Natural Selection' sees grandeur in the view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one. 'Derivation' sees therein a narrow invocation of a special miracle and an unworthy limitation of creative power, the grandeur of which is manifested daily, hourly, in calling into life many forms, by conversion of physical and chemical into vital modes of force, under as many diversified conditions of the requisite elements to be so combined." The view propounded in this work allows, however, a greater and more important part to the share of external influences, it being believed by the Author, however, that these external influences equally with the internal ones are the results of one harmonious action underlying the whole of nature, organic and inorganic, cosmical, physical, chemical, terrestrial, vital, and social. According to this view, an internal law presides over the actions of every part of every individual, and of every organism as a unit, and of the entire organic world as a whole. It is believed that this conception of an internal innate force will ever remain necessary, however much its subordinate processes and actions may become explicable: That by such a force, from time to time, new species are manifested by ordinary generation just as _Pavo nigripennis_ appeared suddenly, these new forms not being monstrosities but harmonious self-consistent wholes. That thus, as specific distinctness is manifested by obscure sexual {240} conditions, so in obscure sexual modifications specific distinctions arise. That these "jumps" are considerable in comparison with the minute variations of "Natural Selection"--are in fact sensible steps, such as discriminate species from species. That the latent tendency which exists to these sudden evolutions is determined to action by the stimulus of external conditions. That "Natural Selection" rigorously destroys monstrosities, and abortive and feeble attempts at the performance of the evolutionary process. That "Natural Selection" removes the antecedent species rapidly when the new one evolved is more in harmony with surrounding conditions. That "Natural Selection" favours and develops useful variations, though it is impotent to originate them or to erect the physiological barrier which seems to exist between species. By some such conception as this, the difficulties here enumerated, which beset the theory of "Natural Selection" pure and simple, are to be got over. Thus, for example, the difficulties discussed in the first chapter--namely, those as to the origins and first beginnings of certain structures--are completely evaded. Again, as to the independent origin of closely similar structures, such as the eyes of the Vertebrata and cuttle-fishes, the difficulty is removed if we may adopt the conception of an innate force similarly directed in each case, and assisted by favourable external conditions. Specific stability, limitation to variability, and the facts of reversion, all harmonize with the view here put forward. The same may be said with regard to the significant facts of homology, and of organic symmetry; and our consideration of the hypothesis of Pangenesis in Chapter X., has seemed to result in a view as to innate powers which accords well with what is here advocated. [Page 241] The evolutionary hypothesis here advocated also serves to explain all those remarkable facts which were stated in the first chapter to be explicable by the theory of Natural Selection, namely, the relation of existing to recent faunas and floras; the phenomena of homology and of rudimentary structures; also the processes gone through in development; and lastly, the wonderful facts of mimicry. Finally, the view adopted is the synthesis of many distinct and, at first sight, conflicting conceptions, each of which contains elements of truth, and all of which it appears to be able more or less to harmonize. Thus it has been seen that "Natural Selection" is accepted. It acts and must act, though alone it does not appear capable of fulfilling the task assigned to it by Mr. Darwin. Pangenesis has probably also much truth in it, and has certainly afforded valuable and pregnant suggestions, but unaided and alone it seems inadequate to explain the evolution of the individual organism. Those three conceptions of the organic world which may be spoken of as the teleological, the typical, and the transmutationist, have often been regarded as mutually antagonistic and conflicting. The genesis of species as here conceived, however, accepts, locates, and harmonizes all the three. Teleology concerns the ends for which organisms were designed. The recognition, therefore, that their formation took place by an evolution not fortuitous, in no way invalidates the acknowledgment of their final causes if on other grounds there are reasons for believing that such final causes exist. Conformity to type, or the creation of species according to certain "divine ideas," is in no way interfered with by such a process of evolution as is here advocated. Such "divine ideas" must be accepted or declined upon quite other grounds than the mode of their realization, and of their manifestation in the world of sensible phenomena. [Page 242] Transmutationism (an old name for the evolutionary hypothesis), which was conceived at one time to be the very antithesis to the two preceding conceptions, harmonizes well with them if the evolution be conceived to be orderly and designed. It will in the next chapter be shown to be completely in harmony with conceptions, upon the acceptance of which "final causes" and "divine ideal archetypes" alike depend. Thus then, if the cumulative argument put forward in this book is valid, we must admit the insufficiency of Natural Selection both on account of the residuary phenomena it fails to explain, and on account of certain other phenomena which seem actually to conflict with that theory. We have seen that though the laws of nature are constant, yet some of the conditions which determine specific change may be exceptionally absent at the present epoch of the world's history; also that it is not only possible, but highly probable, that an internal power or tendency is an important if not the main agent in evoking the manifestation of new species on the scene of realized existence, and that in any case, from the facts of homology, innate internal powers to the full as mysterious must anyhow be accepted, whether they act in specific origination or not. Besides all this, we have seen that it is probable that the action of this innate power is stimulated, evoked, and determined by external conditions, and also that the same external conditions, in the shape of "Natural Selection," play an important part in the evolutionary process: and finally, it has been affirmed that the view here advocated, while it is supported by the facts on which Darwinism rests, is not open to the objections and difficulties which oppose themselves to the reception of "Natural Selection," as the exclusive or even as the main agent in the successive and orderly evolution of organic forms in the _genesis of species_. [Page 243] * * * * * CHAPTER XII. THEOLOGY AND EVOLUTION. Prejudiced opinions on the subject.--"Creation" sometimes denied from prejudice.---The unknowable.--Mr. Herbert Spencer's objections to theism; to creation.--Meanings of term "creation."--Confusion from not distinguishing between "primary" and "derivative" creation.--Mr. Darwin's objections.--Bearing of Christianity on the theory of evolution.--Supposed opposition, the result of a misconception.--Theological authority not opposed to evolution.--St. Augustin.--St. Thomas Aquinas.--Certain consequences of want of flexibility of mind.--Reason and imagination.--The first cause and demonstration.--Parallel between Christianity and natural theology.--What evolution of species is.--Professor Agassiz.--Innate powers must be recognized.--Bearing of evolution on religious belief.--Professor Huxley.--Professor Owen.--Mr. Wallace.--Mr. Darwin.--_A priori_ conception of Divine action.--Origin of man.--Absolute creation and dogma.--Mr. Wallace's view.--A supernatural origin for man's body not necessary.--Two orders of being in man.--Two modes of origin.--Harmony of the physical, hyperphysical, and supernatural.--Reconciliation of science and religion as regards evolution.--Conclusion. The special "Darwinian Theory" and that of an evolutionary process neither excessively minute nor fortuitous, having now been considered, it is time to turn to the important question, whether both or either of these conceptions may have any bearing, and if any, what, upon Christian belief? Some readers will consider such an inquiry to be a work of supererogation. Seeing clearly themselves the absurdity of prevalent popular views, and the shallowness of popular objections, they may be impatient of any discussion, on the subject. But it is submitted that there are many minds worthy {244} of the highest esteem and of every consideration, which have regarded the subject hitherto almost exclusively from one point of view; that there are some persons who are opposed to the progress (in their own minds or in that of their children or dependents) of physical scientific truth--the natural revelation--through a mistaken estimate of its religious bearings, while there are others who are zealous in its promotion from a precisely similar error. For the sake of both these then the Author may perhaps be pardoned for entering slightly on very elementary matters relating to the question, whether evolution or Darwinism have any, and if any, what, bearing on theology? There are at least two classes of men who will certainly assert that they have a very important and highly significant bearing upon it. One of these classes consists of persons zealous for religion indeed, but who identify orthodoxy with their own private interpretation of Scripture or with narrow opinions in which they have been brought up--opinions doubtless widely spread, but at the same time destitute of any distinct and authoritative sanction on the part of the Christian Church. The other class is made up of men hostile to religion, and who are glad to make use of any and every argument which they think may possibly be available against it. Some individuals within this latter class may not believe in the existence of God, but may yet abstain from publicly avowing this absence of belief, contenting themselves with denials of "creation" and "design," though these denials are really consequences of their attitude of mind respecting the most important and fundamental of all beliefs. Without a distinct belief in a personal God it is impossible to have any religion worthy of the name, and no one can at the same time accept the Christian religion and deny the dogma of creation. [Page 245] "I believe in God," "the Creator of Heaven and Earth," the very first clauses of the Apostles' Creed, formally commit those who accept them to the assertion of this belief. If, therefore, any theory of physical science really conflicts with such an authoritative statement, its importance to Christians is unquestionable. As, however, "creation" forms a part of "revelation," and as "revelation" appeals for its acceptance to "reason" which has to prepare a basis for it by an intelligent acceptance of theism on _purely rational grounds_, it is necessary to start with a few words as to the reasonableness of belief in God, which indeed are less superfluous than some readers may perhaps imagine; "a few words," because this is not the place where the argument can be drawn out, but only one or two hints given in reply to certain modern objections. No better example perhaps can be taken, as a type of these objections, than a passage in Mr. Herbert Spencer's First Principles.[246] This author constantly speaks of the "ultimate cause of things" as "the Unknowable," a term singularly unfortunate, and as Mr. James Martineau has pointed out,[247] even self-contradictory: for that entity, the knowledge of {246} the existence of which presses itself ever more and more upon the cultivated intellect, cannot be the unknown, still less _the unknowable_, because we certainly know it, in that we know for certain that it exists. Nay more, to predicate incognoscibility of it, is even a certain knowledge of the mode of its existence. Mr. H. Spencer says:[248] "The consciousness of an Inscrutable Power manifested to us through all phenomena has been growing ever clearer; and must eventually be freed from its imperfections. The certainty that on the one hand such a Power exists, while on the other hand its nature transcends intuition, and is beyond imagination, is the certainty towards which intelligence has from the first been progressing." One would think then that the familiar and accepted word "the Inscrutable" (which is in this passage actually employed, and to which no theologian would object) would be an indefinitely better term than "the unknowable." The above extract has, however, such a theistic aspect that some readers may think the opposition here offered superfluous; it may be well, therefore, to quote two other sentences. In another place he observes,[249] "Passing over the consideration of credibility, and confining ourselves to that of conceivability, we see that atheism, pantheism, and theism, when rigorously analysed, severally prove to be absolutely unthinkable;" and speaking of "every form of religion," he adds,[250] "The analysis of every possible hypothesis proves, not simply that no hypothesis is sufficient but that no hypothesis is even thinkable." The unknowable is admitted to be a power which cannot be regarded as having sympathy with us, but as one to which no emotion whatever can be ascribed, and we are expressly {247} forbidden "by _duty_," to affirm personality of God as much as to deny it of Him. How such a being can be presented as an object on which to exercise religious emotion it is difficult indeed to understand.[251] Aspiration, love, devotion to be poured forth upon what we can never know, upon what we can never affirm to know, or care for, us, our thoughts or actions, or to possess the attributes of wisdom and goodness! The worship offered in such a religion must be, as Professor Huxley says,[252] "for the most part of the silent sort"--silent not only as to the spoken word, but silent as to the mental conception also. It will be difficult to distinguish the follower of this religion from the follower of none, and the man who declines either to assert or to deny the existence of God, is practically in the position of an atheist. For theism enjoins the cultivation of sentiments of love and devotion to God, and the practice of their external expression. Atheism forbids both, while the simply non-theist abstains in conformity with the prohibition of the atheist and thus practically sides with him. Moreover, since man cannot imagine that of which he has no experience in any way whatever, and since he has experience only of _human_ perfections and of the powers and properties of _inferior_ existences; if he be required to deny human perfections and to abstain from making use of such conceptions, he is thereby necessarily reduced to others of an inferior order. Mr. H. Spencer says,[253] "Those who espouse this {248} alternative position, make the erroneous assumption that the choice is between personality and something lower than personality; whereas the choice is rather between personality and something higher. Is it not just possible that there is a mode of being as much transcending intelligence and will, as these transcend mechanical motion?" "It is true we are totally unable to conceive any such higher mode of being. But this is not a reason for questioning its existence; it is rather the reverse." "May we not therefore rightly refrain from assigning to the 'ultimate cause' any attributes whatever, on the ground that such attributes, derived as they must be from our own natures, are not elevations but degradations?" The way however to arrive at the object aimed at (_i.e_. to obtain the best attainable conception of the First Cause) is not to refrain from _the only conceptions possible to us_, but to seek the very highest of these, and then declare their utter inadequacy; and this is precisely the course which has been pursued by theologians. It is to be regretted that before writing on this matter Mr. Spencer did not more thoroughly acquaint himself with the ordinary doctrine on the subject. It is always taught in the Church schools of divinity, that nothing, not even _existence_, is to be predicated _univocally_ of "God" and "creatures;" that after exhausting ingenuity to arrive at the loftiest possible conceptions, we must declare them to be _utterly inadequate_; that, after all, they are but accommodations to human infirmity; that they are in a sense objectively false (because of their inadequacy), though subjectively and very practically true. But the difference between this mode of treatment and that adopted by Mr. Spencer is wide indeed; for the practical result of the mode inculcated by the Church is that each one may freely affirm and act upon the highest human conceptions he can attain of the{249} power, wisdom, and goodness of God, His watchful care, His loving providence for every man, at every moment and in every need; for the Christian knows that the falseness of his conceptions lies only in their _inadequacy_; he may therefore strengthen and refresh himself, may rejoice and revel in conceptions of the goodness of God, drawn from the tenderest human images of fatherly care and love, or he may chasten and abase himself by consideration of the awful holiness and unapproachable majesty of the Divinity derived from analogous sources, knowing that no thought of man can ever be _true enough_, can ever attain the incomprehensible reality, which nevertheless really _is_ all that can be conceived, _plus_ an inconceivable infinity beyond. A good illustration of what is here meant, and of the difference between the theistic position and Mr. Spencer's, may be supplied by an example he has himself proposed. Thus,[254] he imagines an intelligent watch speculating as to its maker, and conceiving of him in terms of watch-being, and figuring him as furnished with springs, escapements, cogged wheels, &c., his motions facilitated by oil--in a word, like himself. It is assumed by Mr. Spencer that this necessary watch conception would be completely false, and the illustration is made use of to show "the presumption of theologians"--the absurdity and unreasonableness of those men who figure the incomprehensible cause of all phenomena as a Being in some way comparable with man. Now, putting aside for the moment all other considerations, and accepting the illustration, surely the example demonstrates rather the unreasonableness of the _objector himself_! It is true, indeed, that a man is an organism indefinitely more complex and perfect than any watch; but if the watch could only conceive of its maker in watch terms, or else in terms altogether inferior, the watch would plainly be right in speaking of its maker as a, to it, inconceivably {250} perfect kind of watch, acknowledging at the same time, that this, its conception of him, was _utterly inadequate_, although the best its inferior nature allowed it to form. For if, instead of so conceiving of its maker, it refused to make use of these relative perfections as a makeshift, and so necessarily thought of him as amorphous metal, or mere oil, or by the help of any other inferior conception which a watch might be imagined capable of entertaining, that watch would he wrong indeed. For man can much more properly be compared with, and has much more affinity to, a perfect watch in full activity than to a mere piece of metal, or drop of oil. But the watch is even more in the right still, for its maker, man, virtually _has_ the cogged wheels, springs, escapements, oil, &c., which the watch's conception has been supposed to attribute to him; inasmuch as all these parts must have existed as distinct ideas in the human watchmaker's mind before he could actually construct the clock formed by him. Nor is even this all, for, by the hypothesis, the watch _thinks_. It must, therefore, think of its maker as "a thinking being," and in this it is _absolutely and completely right_.[255] Either, therefore, the hypothesis is _absurd_ or it actually _demonstrates the very position it was chosen to refute_. Unquestionably, then, on the mere ground taken by Mr. Herbert Spencer himself, if we are compelled to think of the First Cause either in human terms (but with human imperfections abstracted and human perfections carried to the highest conceivable degree), or, on the other hand, in terms decidedly inferior, such as those are driven to who think of Him, but decline to accept as a help the term "personality;" there can be no question but that the first conception is immeasurably nearer the truth than the second. Yet the latter is the one put forward and advocated by that author in spite of its unreasonableness, and in spite also of its{251} conflicting with the whole moral nature of man and all his noblest aspirations. Again, Mr. Herbert Spencer objects to the conception of God as "first cause," on the ground that "when our symbolic conceptions are such that no cumulative or indirect processes of thought can enable us to ascertain that there are corresponding actualities, nor any predictions be made whose fulfilment can prove this, then they are altogether vicious and illusive, and in no way distinguishable from pure fictions."[256] Now, it is quite true that "symbolic conceptions," which are not to be justified either (1) by presentations of sense, or (2) by intuitions, are invalid as representations of real truth. Yet the conception of God referred to _is_ justified by our primary intuitions, and we can assure ourselves that it _does_ stand for an actuality by comparing it with (1) our intuitions of free-will and causation, and (2) our intuitions of morality and responsibility. That we _have_ these intuitions is a point on which the Author joins issue with Mr. Spencer, and confidently affirms that they cannot logically be denied without at the same time complete and absolute scepticism resulting from such denial--scepticism wherein vanishes any certainty as to the existence both of Mr. Spencer and his critic, and by which it is equally impossible to have a thought free from doubt, or to go so far as to affirm the existence of that very doubt or of the doubter who doubts it. It may not be amiss here to protest against the intolerable assumption of a certain school, who are continually talking in lofty terms of "science," but who actually speak of primary religious conceptions as "unscientific," and habitually employ the word "science," when they should limit it by the prefix "physical." This is the more amazing as not a few of this school adopt the idealist philosophy, and affirm that "matter and force" are but names for certain "modes of consciousness." It might be expected of them at least to admit that opinions which repose on primary and fundamental {252} intuitions, are especially and _par excellence_ scientific. Such are some of the objections to the Christian conception of God. We may now turn to those which are directed against God as the Creator, _i.e._ as the absolute originator of the universe, without the employment of any pre-existing means or material. This is again considered by Mr. Spencer as a thoroughly illegitimate symbolic conception, as much so as the atheistic one--the difficulty as to a _self-existent Creator_ being in his opinion equal to that of a _self-existent universe_. To this it may be replied that both are of course equally _unimaginable_, but that it is not a question of facility of conception--not which is easiest to conceive, but which best accounts for, and accords with, psychological facts; namely, with the above-mentioned intuitions. It is contended that _we have_ these primary intuitions, and that with these the conception of a self-existent Creator is perfectly harmonious. On the other hand, the notion of a self-existent universe--that there is no real distinction between the finite and the infinite--that the universe and ourselves are one and the same things with the infinite and the self-existent; these assertions, in _addition to_ being unimaginable, _contradict_ our primary intuitions. Mr. Darwin's objections to "Creation" are of quite a different kind, and, before entering upon them, it will be well to endeavour clearly to understand what we mean by "Creation," in the various senses in which the term may be used. In the strictest and highest sense "Creation" is the absolute origination of anything by God without pre-existing means or material, and is a _supernatural_ act.[257] In the secondary and lower sense, "Creation" is the formation of anything by God _derivatively_; that is, that the preceding matter has been created with the potentiality to evolve from it, under suitable conditions, {253} all the various forms it subsequently assumes. And this power having been conferred by God in the first instance, and those laws and powers having been instituted by Him, through the action of which the suitable conditions are supplied, He is said in this lower sense to create such various subsequent forms. This is the _natural_ action of God in the physical world, as distinguished from His direct, or, as it may be here called, supernatural action. In yet a third sense, the word "Creation" may be more or less improperly applied to the construction of any complex formation or state by a voluntary self-conscious being who makes use of the powers and laws which God has imposed, as when a man is spoken of as the creator of a museum, or of "his own fortune," &c. Such action of a created conscious intelligence is purely natural, but more than physical, and may be conveniently spoken of as hyperphysical. We have thus (1) direct or supernatural action; (2) physical action; and (3) hyperphysical action---the two latter both belonging to the order of nature.[258] Neither the physical nor the hyperphysical actions, however, exclude the idea of the Divine concurrence, and with every consistent theist that idea is necessarily included. Dr. Asa Gray has given expression to this.[259] He says, "Agreeing that plants and animals were produced by Omnipotent fiat, does not exclude the idea of natural order and what we call secondary causes. The record of the fiat--'Let the earth bring forth grass, the herb yielding seed,' &c., 'let the earth bring forth the living creature after his kind'--seems even to imply them," and leads to the conclusion that the various kinds were produced through natural agencies. {254} Now, much confusion has arisen from not keeping clearly in view this distinction between _absolute_ creation and _derivative_ creation. With the first, physical science has plainly nothing whatever to do, and is impotent to prove or to refute it. The second is also safe from any attack on the part of physical science, for it is primarily derived from psychical not physical phenomena. The greater part of the apparent force possessed by objectors to creation, like Mr. Darwin, lies in their treating the assertion of derivative creation as if it was an assertion of absolute creation, or at least of supernatural action. Thus, he asks whether some of his opponents believe "that at innumerable periods in the earth's history, certain elemental atoms have been commanded suddenly to flash into living tissues."[260] Certain of Mr. Darwin's objections, however, are not physical, but _metaphysical_, and really attack the dogma of secondary or derivative creation, though to some perhaps they may appear to be directed against absolute creation only. Thus he uses, as an illustration, the conception of a man who builds an edifice from fragments of rock at the base of a precipice, by selecting for the construction of the various parts of the building the pieces which are the most suitable owing to the shape they happen to have broken into. Afterwards, alluding to this illustration, he says,[261] "The shape of the fragments of stone at the base of our precipice may be called accidental, but this is not strictly correct, for the shape of each depends on a long sequence of events, all obeying natural laws, on the nature of the rock, on the lines of stratification or cleavage, on the form of the mountain which depends on its upheaval and subsequent denudation, and lastly, on the storm and earthquake which threw down the fragments. But in regard to the use to which the fragments may be put, their shape may strictly be said to be{255} accidental. And here we are led to face a great difficulty, in alluding to which I am aware that I am travelling beyond my proper province." "An omniscient Creator must have foreseen every consequence which results from the laws imposed by Him; but can it be reasonably maintained that the Creator intentionally ordered, if we use the words in any ordinary sense, that certain fragments of rock should assume certain shapes, so that the builder might erect his edifice? If the various laws which have determined the shape of each fragment were not predetermined for the builder's sake, can it with any greater probability be maintained that He specially ordained, for the sake of the breeder, each of the innumerable variations in our domestic animals and plants--many of these variations being of no service to man, and not beneficial, far more often injurious, to the creatures themselves? Did He ordain that the crop and tail-feathers of the pigeon should vary, in order that the fancier might make his grotesque pouter and fantail breeds? Did He cause the frame and mental qualities of the dog to vary, in order that a breed might be formed of indomitable ferocity, with jaws fitted to pin down the bull for man's brutal sport? But, if we give up the principle in one case---if we do not admit that the variations of the primeval dog were intentionally guided, in order that the greyhound, for instance, that perfect image of symmetry and vigour, might be formed,--no shadow of reason can be assigned for the belief that the variations, alike in nature, and the result of the same general laws, which have been the groundwork through Natural Selection of the formation of the most perfectly adapted animals in the world, man included, were intentionally and specially guided. However much we may wish it, we can hardly follow Professor Asa Gray in his belief that 'variation has been led along certain beneficial lines,' like a stream 'along definite and useful lines of irrigation.'" "If we assume that each particular variation was from the beginning of{256} all time pre-ordained, the plasticity of the organization, which leads to many injurious deviations of structure, as well as that redundant power of reproduction which inevitably leads to a struggle for existence, and, as a consequence, to the Natural Selection and survival of the fittest, must appear to us superfluous laws of nature. On the other hand, an omnipotent and omniscient Creator ordains everything and foresees everything. Thus we are brought face to face with a difficulty as insoluble as is that of freewill and predestination." Before proceeding to reply to this remarkable passage, it may be well to remind some readers that belief in the existence of God, in His primary creation of the universe, and in His derivative creation of all kinds of being, inorganic and organic, do not repose upon physical phenomena, but, as has been said, on primary intuitions. To deny or ridicule any of these beliefs on physical grounds is to commit the fallacy of _ignoratio elenchi_. It is to commit an absurdity analogous to that of saying a blind child could not recognize his father because he could not _see_ him, forgetting that he could _hear_ and _feel_ him. Yet there are some who appear to find it unreasonable and absurd that men should regard phenomena in a light not furnished by or deducible from the very phenomena themselves, although the men so regarding them avow that the light in which they do view them comes from quite another source. It is as if a man, A, coming into B's room and finding there a butterfly, should insist that B had no right to believe that the butterfly had not flown in at the open window, inasmuch as there was nothing about the room or insect to lead to any other belief; while B can well sustain his right so to believe, he having met C, who told him he brought in the chrysalis and, having seen the insect emerge, took away the skin. By a similarly narrow and incomplete view the assertion that human conceptions, such as "the vertebrate idea," &c., are ideas in the mind of God, is sometimes ridiculed; as if the assertors either on the one {257} hand pretended to some prodigious acuteness of mind--a far-reaching genius not possessed by most naturalists--or, on the other hand, as if they detected in the very phenomena furnishing such special conception evidences of Divine imaginings. But let the idea of God, according to the highest conceptions of Christianity, be once accepted, and then it becomes simply a truism to say that the mind of the Deity contains all that is _good_ and _positive_ in the mind of man, _plus_, of course, an absolutely inconceivable infinity beyond. That thus such human conceptions may, nay must, be asserted to be at the same time ideas in the Divine mind also, as every real and separate individual that has been, is, or shall be, is present to the same mind. Nay, more, that such human conceptions are but faint and obscure adumbrations of corresponding ideas which exist in the mind of God in perfection and fulness.[262] The theist, having arrived at his theistic convictions from quite other sources than a consideration of zoological or botanical phenomena, {258} returns to the consideration of such phenomena and views them in a theistic light without of course asserting or implying that such light has been derived _from them_, or that there is an obligation of reason so to view them on the part of others who refuse to enter upon or to accept those other sources whence have been derived the theistic convictions of the theist. But Mr. Darwin is not guilty of arguing against metaphysical ideas on physical grounds only, for he employs very distinctly metaphysical ones; namely, his conceptions of the nature and attributes of the First Cause. But what conceptions does he offer us? Nothing but that low anthropomorphism which, unfortunately, he so often seems to treat as the necessary result of Theism. It is again the dummy, helpless and deformed, set up merely for the purpose of being knocked down. It must once more be insisted on, that though man is indeed compelled to conceive of God in human terms, and to speak of Him by epithets objectively false, from their hopeless inadequacy, yet nevertheless the Christian thinker declares that inadequacy in the strongest manner, and vehemently rejects from his idea of God all terms distinctly implying infirmity or limitation. Now, Mr. Darwin speaks as if all who believe in the Almighty were compelled to accept as really applicable to the Deity conceptions which affirm limits and imperfections. Thus he says: "Can it be reasonably maintained that the Creator intentionally ordered" "that certain fragments of rock should assume certain shapes, so that the builder might erect his edifice?" Why, surely every theist must maintain that in the first foundation of the universe--the primary and absolute creation--God saw and knew every purpose which every atom and particle of matter should ever subserve in all suns and systems, and throughout all coming æons of time. It is almost incredible, but nevertheless it seems necessary to think that the difficulty thus proposed rests on a sort of notion that amidst the boundless profusion of nature there is too much for God to superintend; that the number of objects is too great for an infinite and {259} _omnipresent_ being to attend singly to each and all in their due proportions and needs! In the same way Mr. Darwin asks whether God can have ordered the race variations referred to in the passage last quoted, for the considerations therein mentioned. To this it may be at once replied that even man often has _several_ distinct intentions and motives for a _single_ action, and the theist has no difficulty in supposing that, out of an infinite number of motives, the motive mentioned in each case may have been an exceedingly subordinate one. The theist, though properly attributing to God what, for want of a better term, he calls "purpose" and "design," yet affirms that the limitations of human purposes and motives are by no means applicable to the Divine "purposes." Out of many, say a thousand million, reasons for the institution of the laws of the physical universe, some few are to a certain extent conceivable by us; and amongst these the benefits, material and moral, accruing from them to men, and to each individual man in every circumstance of his life, play a certain, perhaps a very subordinate, part.[263] As Baden Powell observes, "How can we {260} undertake to affirm, amid all the possibilities of things of which we confessedly know so little, that a thousand ends and purposes may not be answered, because we can trace none, or even imagine none, which seem to our short-sighted faculties to be answered in these particular arrangements?"[264] The objection to the bull-dog's ferocity in connexion with "man's brutal sport" opens up the familiar but vast question of the existence of evil, a problem the discussion of which would be out of place here. Considering, however, the very great stress which is laid in the present day on the subject of animal suffering by so many amiable and excellent people, one or two remarks on that matter may not be superfluous. To those who accept the belief in God, the soul and moral responsibility; and recognize the full results of that acceptance--to such, physical suffering and moral evil are simply incommensurable. To them the placing of non-moral beings in the same scale with moral agents will be utterly unendurable. But even considering physical pain only, all must admit that this depends greatly on the mental condition of the sufferer. Only during consciousness does it exist, and only in the most highly-organized men does it reach its acme. The Author has been assured that lower races of men appear less keenly sensitive to physical pain than do more cultivated and refined human beings. Thus only in man can there really be any intense degree of suffering, because only in him is there that intellectual recollection of past moments and that anticipation of future ones, which constitute in great part the bitterness of suffering.[265] The momentary pang, the present pain, which beasts endure, though real enough, is yet, doubtless, not to be compared as {261} to its intensity with the suffering which is produced in man through his high prerogative of self-consciousness.[266] As to the "beneficial lines" (of Dr. Asa Gray, before referred to), some of the facts noticed in the preceding chapters seem to point very decidedly in that direction, but all must admit that the actual existing outcome is far more "beneficial" than the reverse. The natural universe has resulted in the development of an unmistakable harmony and beauty, and in a decided preponderance of good and of happiness over their opposites. Even if "laws of nature" did appear, on the theistic hypothesis, to be "superfluous" (which it is by no means intended here to admit), it would be nothing less than puerile to prefer rejecting the hypothesis to conceiving that the appearance of superfluity was probably due to human ignorance; and this especially might be expected from naturalists to whom the interdependence of nature and the harmony and utility of obscure phenomena are becoming continually more clear, as, _e.g._, the structure of orchids to their illustrious expositor. Having now cleared the ground somewhat, we may turn to the question what bearing Christian dogma has upon evolution, and whether Christians, as such, need take up any definite attitude concerning it. As has been said, it is plain that physical science and "evolution" _can_ have nothing whatever to do with absolute or primary creation. The Rev. Baden Powell well expresses this, saying: "Science demonstrates incessant past changes, and dimly points to yet earlier links in a more vast series of development of material existence; but the idea of a _beginning_, or of _creation_, in the sense of the original operation of the Divine volition to constitute nature and matter, is beyond the province of physical {262} philosophy."[267] With secondary or derivative creation, physical science is also incapable of conflict; for the objections drawn by some writers seemingly from physical science, are, as has been already argued, rather metaphysical than physical. Derivative creation is not a supernatural act, but is simply the Divine action by and through natural laws. To recognize such action in such laws is a religious mode of regarding phenomena, which a consistent theist must necessarily accept, and which an atheistic believer must similarly reject. But this conception, if deemed superfluous by any naturalist, can never be shown to be _false_ by any investigations concerning natural laws, the constant action of which it presupposes. The conflict has arisen through a misunderstanding. Some have supposed that by "creation" was necessarily meant either primary, that is, absolute creation, or, at least, some supernatural action; they have therefore opposed the dogma of "creation" in the imagined interest of physical science. Others have supposed that by "evolution" was necessarily meant a denial of Divine action, a negation of the providence of God. They have therefore combated the theory of "evolution" in the imagined interest of religion. It appears plain then that Christian thinkers are perfectly free to accept the general evolution theory. But are there any theological authorities to justify this view of the matter? Now, considering how extremely recent are these biological speculations, it might hardly be expected _a priori_ that writers of earlier ages should have given expression to doctrines harmonizing in any degree with such very modern views,[268] nevertheless such most certainly is the case, and {263} it would be easy to give numerous examples. It will be better, however, only to cite one or two authorities of weight. Now, perhaps no writer {264} of the earlier Christian ages could be quoted whose authority is more generally recognized than that of St. Augustin. The same may be said of the mediæval period, for St. Thomas Aquinas; and, since the movement of Luther, Suarez may be taken as a writer widely venerated as an authority and one whose orthodoxy has never been questioned. It must be borne in mind that for a considerable time after even the last of these writers no one had disputed the generally received view as to the small age of the world or at least of the kinds of animals and plants inhabiting it. It becomes therefore much more striking if views formed under such a condition of opinion are found to harmonize with modern ideas regarding "Creation" and organic life. Now St. Augustin insists in a very remarkable manner on the merely derivative sense in which God's creation of organic forms is to be understood; that is, that God created them by conferring on the material world the power to evolve them under suitable conditions. He says in his book on Genesis:[269] "Terrestria animalia, tanquam ex ultimo elemento mundi ultima; nihilominus _potentialiter_, quorum numeros tempus postea visibiliter explicaret." Again he says:-- "Sicut autem in ipso grano invisibiliter erant omnia simul, quæ per tempora in arborem surgerent; ita ipse mundus cogitandus est, cum Deus _simul omnia creavit_, habuisse simul omnia quæ in illo et cum illo facta sunt quando factus est dies; non solum coelum cum sole et lunâ et sideribus ... ; sed etiam illa quæ aqua et terra produxit potentialiter atque causaliter, priusquam per temporum moras ita exorirentur, quomodo nobis jam nota sunt in eis operibus, quæ Deus usque nunc operatur."[270] "Omnium quippe rerum quæ corporaliter visibiliterque nascuntur, {265} occulta quædam semina in istis corporeis mundi hujus elementis latent."[271] And again: "Ista quippe originaliter ac primordialiter in quadam textura elementorum cuncta jam creata sunt; sed acceptis opportunitatibus prodeunt."[272] St. Thomas Aquinas, as was said in the first chapter, quotes with approval the saying of St. Augustin that in the first institution of nature we do not look for _Miracles_, but for the _laws of Nature_: "In prima institutione naturæ non quæritur miraculum, sed quid natura rerum habeat, ut Augustinus dicit."[273] Again, he quotes with approval St. Augustin's assertion that the kinds were created only derivatively, "_potentialiter tantum_."[274] Also he says, "In prima autem rerum institutione fuit principium activum verbum Dei, quod de materia elementari produxit animalia, vel in actu vel _virtute_, secundum Aug. lib. 5 de Gen. ad lit. c. 5."[275] Speaking of "kinds" (in scholastic phraseology "substantial forms") latent in matter, he says: "Quas quidam posuerunt non incipere per actionem naturæ sed prius in materia exstitisse, ponentes latitationem formarum. Et hoc accidit eis ex ignorantia materiæ, quia nesciebant distinguere inter potentiam et actum. Quia enim formæ præexistunt eas simpliciter præexistere."[276] Also Cornelius à Lapide[277] contends that at least certain animals were not absolutely, but only derivatively created, saying of them, "Non fuerunt creata formaliter, sed potentialiter." As to Suarez, it will be enough to refer to Disp. xv., 2, n. 9, p. 508, t. i. Edition _Vives_, Paris; also Nos. 13--15, and many other references{266} to the same effect could easily be given, but these may suffice. It is then evident that ancient and most venerable theological authorities distinctly assert _derivative_ creation, and thus harmonize with all that modern science can possibly require. It may indeed truly be said with Roger Bacon, "The saints never condemned many an opinion which the moderns think ought to be condemned."[278] The various extracts given show clearly how far "evolution" is from any necessary opposition to the most orthodox theology. The same may be said of spontaneous generation. The most recent form of it, lately advocated by Dr. H. Charlton Bastian,[279] teaches that matter exists in two different forms, the crystalline (or statical) and the colloidal (or dynamical) conditions. It also teaches that colloidal matter, when exposed to certain conditions, presents the phenomena of life, and that it can be formed from crystalline matter, and thus that the _prima materia_ of which these are diverse forms contains potentially all the multitudinous kinds of animal and vegetable existence. This theory moreover harmonizes well with the views here advocated, for just as crystalline matter builds itself, under suitable conditions, along _certain definite lines_, so analogously colloidal matter has _its definite lines and directions_ of development. It is not collected in haphazard, accidental aggregations, but evolves according to its proper laws and special properties. The perfect orthodoxy of these views is unquestionable. Nothing is plainer from the venerable writers quoted, as well as from a mass of other {267} authorities, than that "the supernatural" is not to be looked for or expected in the sphere of mere nature. For this statement there is a general _consensus_ of theological authority. The teaching which the Author has received is, that God is indeed inscrutable and incomprehensible to us from the infinity of His attributes, so that our minds can, as it were, only take in, in a most fragmentary and indistinct manner (as through a glass darkly), dim conceptions of infinitesimal portions of His inconceivable perfection. In this way the partial glimpses obtained by us in different modes differ from each other; not that God is anything but the most perfect unity, but that apparently conflicting views arise from our inability to apprehend Him, except in this imperfect manner, _i.e._ by successive slight approximations along different lines of approach. Sir William Hamilton has said,[280] "Nature conceals God, and man reveals Him." It is not, according to the teaching spoken of, exactly thus; but rather that physical nature reveals to us one side, one aspect of the Deity, while the moral and religious worlds bring us in contact with another, and at first, to our apprehension, a very different one. The difference and discrepancy, however, which is at first felt, is soon seen to proceed not from the reason but from a want of flexibility in the imagination. This want is far from surprising. Not only may a man naturally be expected to be an adept in his own art, but at the same time to show an incapacity for a very different mode of activity.[281] We rarely find an artist who takes much interest in jurisprudence, or {268} a prizefighter who is an acute metaphysician. Nay, more than this, a positive distaste may grow up, which, in the intellectual order, may amount to a spontaneous and unreasoning disbelief in that which appears to be in opposition to the more familiar concept, and this at all times. It is often and truly said, "that past ages were pre-eminently credulous as compared with our own, yet the difference is not so much in the amount of the credulity, as in the direction which it takes."[282] Dr. Newman observes: "Any one study, of whatever kind, exclusively pursued, deadens in the mind the interest, nay the perception of any other. Thus Cicero says, that Plato and Demosthenes, Aristotle and Isocrates, might have respectively excelled in each other's province, but that each was absorbed in his own. Specimens of this peculiarity occur every day. You can hardly persuade some men to talk about anything but their own pursuit; they refer the whole world to their own centre, and measure all matters by their own rule, like the fisherman in the drama, whose eulogy on his deceased lord was 'he was so fond of fish.'"[283] The same author further says:[284] "When anything, which comes before us, is very unlike what we commonly experience, we consider it on that account untrue; not because it really shocks our reason as improbable, but because it startles our imagination as strange. Now, revelation presents to us a perfectly different aspect of the universe from that presented by the sciences. The two informations are like the distinct subjects represented by the lines of the same drawing, which, accordingly as they are read {269} on their concave or convex side, exhibit to us now a group of trees with branches and leaves, and now human faces." ... "While then reason and revelation are consistent in fact, they often are inconsistent in appearance; and this seeming discordance acts most keenly on the imagination, and may suddenly expose a man to the temptation, and even hurry him on to the commission of definite acts of unbelief, in which reason itself really does not come into exercise at all."[285] Thus we find in fact just that distinctness between the ideas derived from physical science on the one hand and from religion on the other, which we might _a priori_ expect if there exists that distinctness between the natural and the miraculous which theological authorities lay down. Assuming, for argument's sake, the truth of Christianity, it evidently has not been the intention of its Author to make the evidence for it so plain that its rejection would be the mark of intellectual incapacity. Conviction is not forced upon men in the way that the knowledge that the government of England is constitutional, or that Paris is the capital of France, is forced upon all who choose to inquire into those subjects. The Christian system is one which puts on the strain, as it were, _every_ faculty of man's nature, and the intellect is not (any more than we should _a priori_ expect it to be) exempted from taking part in the probationary trial. A moral element enters into the acceptance of that system. And so with natural religion--with those ideas of the supernatural, viz. God, Creation, and Morality, which are anterior to revelation and repose upon reason. Here again it evidently has not been the intention of the Creator to make the evidence of His existence so plain that its non-recognition would be the mark of intellectual incapacity. {270} Conviction, as to theism, is not forced upon men as is the conviction of the existence of the sun at noon-day.[286] A moral element enters also here, and the analogy there is in this respect between Christianity and theism speaks eloquently of their primary derivation from one common author. Thus we might expect that it would be a vain task to seek anywhere in nature for evidence of Divine action, such that no one could sanely deny it. God will not allow Himself to be caught at the bottom of any man's crucible, or yield Himself to the experiments of gross-minded and irreverent inquirers. The natural, like the supernatural, revelation appeals to _the whole_ of man's mental nature and not to the _reason alone_.[287] None, therefore, need feel disappointed that evidence of the direct action of the first cause in merely natural phenomena ever eludes our grasp; for assuredly those same phenomena will ever remain fundamentally inexplicable by physical science alone. There being then nothing in either authority or reason which makes "evolution" repugnant to Christianity, is there anything in the Christian doctrine of "Creation" which is repugnant to the theory of "evolution"? Enough has been said as to the distinction between absolute and derivative "creation." It remains to consider the successive "evolution" (Darwinian and other) of "specific forms," in a theological light. As to what "evolution" is, we cannot of course hope to explain it completely, but it may be enough to define it as the manifestation to the intellect, by means of sensible impressions, of some ideal entity (power, principle, nature, or activity) which before that manifestation was in{271} a latent, unrealized, and merely "potential" state--a state that is capable of becoming realized, actual, or manifest, the requisite conditions being supplied. "Specific forms," kinds or species, are (as was said in the introductory chapter) "peculiar congeries of characters or attributes, innate powers and qualities, and a certain nature realized in individuals." Thus, then, the "evolution of specific forms" means the actual manifestation of special powers, or natures, which before were latent, in such a successive manner that there is in some way a genetic relation between posterior manifestations and those which preceded them. On the special Darwinian hypothesis the manifestation of these forms is determined simply by the survival of the fittest of many indefinite variations. On the hypothesis here advocated the manifestation is controlled and helped by such survival, but depends on some unknown internal law or laws which determine variation at special times and in special directions. Professor Agassiz objects to the evolution theory, on the ground that "species, genera, families, &c., exist as thoughts, individuals as facts,"[288] and he offers the dilemma, "If species do not exist at all, as the supporters of the transmutation theory maintain, how can they vary? and if individuals alone exist, how can the differences which may be observed among them prove the variability of species?" But the supporter of "evolution" need only maintain that the several "kinds" become manifested gradually by slight differences among the various individual embodiments of one specific idea. He might reply to the dilemma by saying, species do not exist _as species_ in the sense in which they are said to vary (variation applying only to the concrete embodiments of {272} the specific idea), and the evolution of species is demonstrated not by individuals _as individuals_, but as embodiments of different specific ideas. Some persons seem to object to the term "creation" being applied to evolution, because evolution is an "exceedingly slow and gradual process." Now even if it were demonstrated that such is really the case, it may be asked, what is "slow and gradual"? The terms are simply relative, and the evolution of a specific form in ten thousand years would be instantaneous to a being whose days were as hundreds of millions of years. There are others again who are inclined absolutely to deny the existence of species altogether, on the ground that their evolution is so gradual that if we could see all the stages it would be impossible to say _when_ the manifestation of the old specific form ceased and that of the new one began. But surely it is no approach to a reason against the existence of a thing that we cannot determine the exact moment of its first manifestation. When watching "dissolving views," who can tell, whilst closely observing the gradual changes, exactly at what moment a new picture, say St. Mark's, Venice, can be said to have commenced its manifestation, or have begun to dominate a preceding representation of "Dotheboys' Hall"? That, however, is no reason for denying the complete difference between the two pictures and the ideas they respectively embody. The notion of a special nature, a peculiar innate power and activity--what the scholastics called a "substantial form"--will be distasteful to many. The objection to the notion seems, however, to be a futile one, for it is absolutely impossible to altogether avoid such a conception and such an assumption. If we refuse it to the individuals which embody the species, we must admit it as regards their component parts--nay, even if we accept the hypothesis of pangenesis, we are nevertheless compelled to attribute to each gemmule that peculiar power of reproducing its own nature (its own "substantial form"), with its special activity, and that remarkable {273} power of annexing itself to certain other well-defined gemmules whose nature it is also to plant themselves in a certain definite vicinity. So that in each individual, instead of one such peculiar power and activity dominating and controlling all the parts, you have an infinity of separate powers and activities limited to the several minute component gemmules. It is possible that in some minds, the notion may lurk that such powers are simpler and easier to understand, because the bodies they affect are so minute! This absurdity hardly bears stating. We can easily conceive a being so small, that a gemmule would be to it as large as St. Paul's would be to us. Admitting then the existence of species, and of their successive evolution, is there anything in these ideas hostile to Christian belief? Writers such as Vogt and Buchner will of course contend that there is; but naturalists, generally, assume that God acts in and by the various laws of nature. And this is equivalent to admitting the doctrine of "derivative creation." With very few exceptions, none deny such Divine concurrence. Even "design" and "purpose" are recognized as quite compatible with evolution, and even with the special "nebular" and Darwinian forms of it. Professor Huxley well says,[289] "It is necessary to remark that there is a wider teleology, which is not touched by the doctrine of evolution, but is actually based upon the fundamental proposition of evolution." ... "The teleological and the mechanical views of nature are not necessarily mutually exclusive; on the contrary, the more purely a mechanist the speculator is, the more firmly does he assume a primordial molecular arrangement, of which all the phenomena of the universe are the consequences; and the more completely thereby is he at the mercy of the teleologist, who can always defy him to disprove that this primordial {274} molecular arrangement was not intended to evolve the phenomena of the universe."[290] Professor Owen says, that natural evolution, through secondary causes, "by means of slow physical and organic operations through long ages, is not the less clearly recognizable as the act of all adaptive mind, because we have abandoned the old error of supposing it to be the result[291] of a primary, direct, and sudden act of creational construction." ... "The succession of species by continuously operating law, is not necessarily a 'blind operation.' Such law, however discerned in the properties and successions of natural objects, intimates, nevertheless, a preconceived progress. Organisms may be evolved in orderly succession, stage after stage, towards a foreseen goal, and the broad features of the course may still show the unmistakable impress of Divine volition." Mr. Wallace[292] declares that the opponents of evolution present a less elevated view of the Almighty. He says: "Why should we suppose the machine too complicated to have been designed by the Creator so complete that it would necessarily work out harmonious results? The theory of 'continual interference' is a limitation of the Creator's power. It assumes that He could not work by pure law in the organic, as He has done in the inorganic world." Thus, then, there is not only no necessary antagonism between the general theory of "evolution" and a Divine action, but the compatibility between the two is recognized by naturalists who cannot be suspected of any strong theological bias. {275} The very same may be said as to the special Darwinian form of the theory of evolution. It is true Mr. Darwin writes sometimes as if he thought that his theory militated against even _derivative creation_.[293] This, however, there is no doubt, was not really meant; and indeed, in the passage before quoted and criticised, the possibility of the Divine ordination of each variation is spoken of as a tenable view. He says ("Origin of Species," p. 569), "I see no good reason why the views given in this volume should shock the religious feelings of anyone;" and he speaks of life "having been originally breathed by the Creator into a few forms or into one," which is _more_ than the dogma of creation actually requires. We find then that no _in_compatibility is asserted (by any scientific writers worthy of mention) between "evolution" and the co-operation of the Divine will; while the same "evolution" has been shown to be thoroughly acceptable to the most orthodox theologians who repudiate the intrusion of the supernatural into the domain of nature. A more complete harmony could scarcely be desired. But if we may never hope to find, in physical nature, evidence of supernatural action, what sort of action might we expect to find there, looking at it from a theistic point of view? Surely an action the results of which harmonize with man's reason,[294] which is orderly, which {276} disaccords with the action of blind chance and with the "fortuitous concourse of atoms" of Democritus; but at the same time an action which, as to its modes, ever, in parts, and in ultimate analysis, eludes our grasp, and the modes of which are different from those by which we should have attempted to accomplish such ends. Now, this is just what we _do_ find. The harmony, the beauty, and the order of the physical universe are the themes of continual panegyrics on the part of naturalists, and Mr. Darwin, as the Duke of Argyll remarks,[295] "exhausts every form of words and of illustration by which intention or mental purpose can be described"[296] when speaking of the wonderfully complex adjustments to secure the fertilization of orchids. Also, we find co-existing with this harmony a mode of proceeding so different from that of man as (the direct supernatural action eluding us) to form a stumbling-block to many in the way of their recognition of Divine action at all: although nothing can be more inconsistent than to speak of the first cause as utterly inscrutable and incomprehensible, and at the same time to expect to find traces of a mode of action exactly similar to our own. It is surely enough if the results harmonize on the whole and preponderatingly with the rational, moral, and æsthetic instincts of man. Mr. J. J. Murphy[297] has brought strongly forward the evidence of "intelligence" throughout organic nature. He believes "that there is something in organic progress which mere Natural Selection among spontaneous variations will not account for," and that "this something is that organizing intelligence which guides the action of the inorganic forces, and forms structures which neither Natural Selection nor any other unintelligent agency could form." {277} This intelligence, however, Mr. Murphy considers may be unconscious, a conception which it is exceedingly difficult to understand, and which to many minds appears to be little less than a contradiction in terms; the very first condition of an intelligence being that, if it knows anything, it should at least know its own existence. Surely the evidence from physical facts agrees well with the overruling, concurrent action of God in the order of nature; which is no miraculous action, but the operation of laws which owe their foundation, institution, and maintenance to an omniscient Creator of whose intelligence our own is a feeble adumbration, inasmuch as it is created in the "image and likeness" of its Maker. This leads to the final consideration, a difficulty by no means to be passed over in silence, namely the ORIGIN OF MAN. To the general theory of Evolution, and to the special Darwinian form of it, no exception, it has been shown, need be taken on the ground of orthodoxy. But in saying this, it has not been meant to include the soul of man. It is a generally received doctrine that the soul of every individual man is absolutely created in the strict and primary sense of the word, that it is produced by a direct or supernatural[298] act, and, of course, that by such an act the soul of the first man was similarly created. It is therefore important to inquire whether "evolution" conflicts with this doctrine. Now the two beliefs are in fact perfectly compatible, and that either on the hypothesis--1. That man's body was created in a manner different in kind from that by which the bodies of other animals were created; or 2. That it was created in a similar manner to theirs. One of the authors of the Darwinian theory, indeed, contends that even{278} as regards man's body, an action took place different from that by which brute forms were evolved. Mr. Wallace[299] considers that "Natural Selection" alone could not have produced so large a brain in the savage, in possessing which he is furnished with an organ beyond his needs. Also that it could not have produced that peculiar distribution of hair, especially the nakedness of the back, which is common to all races of men, nor the peculiar construction of the feet and hands. He says,[300] after speaking of the prehensile foot, common without a single exception to all the apes and lemurs, "It is difficult to see why the prehensile power should have been taken away" by the mere operation of Natural Selection. "It must certainly have been useful in climbing, and the case of the baboons shows that it is quite compatible with terrestrial locomotion. It may not be compatible with perfectly easy erect locomotion; but, then, how can we conceive that early man, _as an animal_, gained anything by purely erect locomotion? Again, the hand of man contains latent capacities and powers which are unused by savages, and must have been even less used by palæolithic man and his still ruder predecessors. It has all the appearance of an organ prepared for the use of civilized man, and one which was required to render civilization possible." Again speaking of the "wonderful power, range, flexibility, and sweetness of the musical sounds producible by the human larynx," he adds, "The habits of savages give no indication of how this faculty could have been developed by Natural Selection; because it is never required or used by them. The singing of savages is a more or less monotonous howling, and the females seldom sing at all. Savages certainly never choose their wives for fine voices, but for rude health, and strength and physical beauty. Sexual selection could not therefore have developed this wonderful power, which only comes into play among civilized people. It seems as if the organ had been prepared in anticipation of the future {279} progress of man, since it contains latent capacities which are useless to him in his earlier condition. The delicate correlations of structure that give it such marvellous powers, could not therefore have been acquired by means of Natural Selection." [Illustration: FIBRES OF CORTI.] To this may be added the no less wonderful faculty in the ear of appreciating delicate musical tones, and the harmony of chords. It matters not what part of the organ subserves this function, but it has been supposed that it is ministered to by the fibres _of Corti_.[301] Now it can hardly be contended that the preservation of any race of men in the struggle for life could have depended on such an extreme delicacy and refinement of the internal ear,[302]--a perfection only fully exercised in the enjoyment and appreciation of the most exquisite musical performances. Here, surely, we have an instance of an organ preformed, ready beforehand for such action as could never by itself have been the cause of its development,--the action having only been subsequent, not anterior. The Author is not aware what may be the minute structure of the internal ear in the highest apes, but if (as from analogy is probable) it is much as in man, then _a fortiori_ we have an instance of _anticipatory_ development of a most marked and unmistakable kind. And this is not all. There is no {280} reason to suppose that any animal besides man appreciates musical _harmony_. It is certain that no other one _produces_ it. Mr. Wallace also urges objections drawn from the origin of some of man's mental faculties, such as "the capacity to form ideal conceptions of space and time, of eternity and infinity--the capacity for intense artistic feelings of pleasure, in form, colour and composition--and for those abstract notions of form and number which render geometry and arithmetic possible," also from the origin of the moral sense.[303] The validity of these objections is fully conceded by the Author of this book, but he would push it much further, and contend (as has been now repeatedly said), that another law, or other laws, than "Natural Selection" have determined the evolution of _all_ organic forms, and of inorganic forms also. And it must be contended that Mr. Wallace, in order to be quite self-consistent, should arrive at the very same conclusion, inasmuch as he is inclined to trace all phenomena to the action of superhuman WILL. He says:[304] "If therefore we have traced one force, however minute, to an origin in our own WILL, while we have no knowledge of any other primary cause of force, it does not seem an improbable conclusion that all force may be will-force; and thus, that the whole universe is not merely dependent on, but actually _is_, the WILL of higher intelligences, or of one Supreme Intelligence." If there is really evidence, as Mr. Wallace believes, of the action of an overruling intelligence in the evolution of the "human form divine;" if we may go so far as this, then surely an analogous action may well be traced in the production of the horse, the camel, or the dog, so largely identified with human wants and requirements. And if from other than physical considerations we may believe that such action, though undemonstrable, has been and is; then (reflecting on sensible {281} phenomena the theistic light derived from psychical facts) we may, in the language of Mr. Wallace, "see indications of that power in facts which, by themselves, would not serve to prove its existence."[305] Mr. Murphy, as has been said before, finds it necessary to accept the wide-spread action of "intelligence" as the agent by which _all_ organic forms have been called forth from the inorganic. But all science tends to unity, and this tendency makes it reasonable to extend to all physical existences a mode of formation which we may have evidence for in any _one_ of them. It therefore makes it reasonable to extend, if possible, the very same agency which we find operating in the field of biology, also to the inorganic world. If on the grounds brought forward the action of intelligence may be affirmed in the production of man's bodily structure, it becomes probable _a priori_ that it may also be predicated of the formative action by which has been produced the animals which minister to him, and all organic life whatsoever. Nay more, it is then congruous to expect analogous action in the development of crystalline and colloidal structures, and in that of all chemical compositions, in geological evolutions, and the formation not only of this earth, but of the solar system and whole sidereal universe. If such really be the direction in which physical science, philosophically considered, points; if intelligence may thus be seen to preside over the evolution of each system of worlds and the unfolding of every blade of grass--this grand result harmonizes indeed with the teachings of faith that God acts and concurs, in the natural order, with those laws of the material universe which were not only instituted by His will, but are sustained by His concurrence; and we are thus enabled to discern in the natural order, however darkly, the Divine Author of nature--Him in whom "we live, and move, and have our being." But if this view is accepted, then it is no longer absolutely {282} necessary to suppose that any action different in kind took place in the production of man's body, from that which took place in the production of the bodies of other animals, and of the whole material universe. Of course, if it _can_ be demonstrated that that difference which Mr. Wallace asserts really exists, it is plain that we then have to do with facts not only harmonizing with religion, but, as it were, preaching and proclaiming it. It is not, however, necessary for Christianity that any such view should prevail. Man, according to the old scholastic definition, is "a rational animal" (_animal rationale_), and his animality is distinct in nature from his rationality, though inseparably joined, during life, in one common personality. This animal body must have had a different source from that of the spiritual soul which informs it, from the distinctness of the two orders to which those two existences severally belong. Scripture seems plainly to indicate this when it says that "God made man from the dust of the earth, and breathed into his nostrils the breath of life." This is a plain and direct statement that man's _body_ was _not_ created in the primary and absolute sense of the word, but was evolved from pre-existing material (symbolized by the term "dust of the earth"), and was therefore only _derivatively created_, i.e. by the operation of secondary laws. His _soul_, on the other hand, was created in quite a different way, not by any pre-existing means, external to God himself, but by the direct action of the Almighty, symbolized by the term "breathing:" the very form adopted by Christ, when conferring the _supernatural_ powers and graces of the Christian dispensation, and a form still daily used in the rites and ceremonies of the Church. That the first man should have had this double origin agrees with what we now experience. For supposing each human soul to be directly and immediately created, yet each human body is evolved by the ordinary operation of natural physical laws. [Page 283] Professor Flower in his Introductory Lecture[306] (p. 20) to his course of Hunterian Lectures for 1870 well observes: "Whatever man's place may be, either _in_ or _out_ of nature, whatever hopes, or fears or feelings about himself or his race he may have, we all of us admit that these are quite uninfluenced by our knowledge of the fact that each individual man comes into the world by the ordinary processes of generation, according to the same laws which apply to the development of all organic beings whatever, that every part of him which can come under the scrutiny of the anatomist or naturalist, has been evolved according to these regular laws from a simple minute ovum, indistinguishable to our senses from that of any of the inferior animals. If this be so--if man is what he is, notwithstanding the corporeal mode of origin of the individual man, so he will assuredly be neither less nor more than man, whatever may be shown regarding the corporeal origin of the whole race, whether this was from the dust of the earth, or by the modification of some pre-existing animal form." Man is indeed compound, in him two distinct orders of being impinge and mingle; and with this an origin from two concurrent modes of action is congruous, and might be expected _a priori_. At the same time as the "soul" is "the form of the body," the former might be expected to modify the latter into a structure of harmony and beauty standing alone in the organic world of nature. Also that, with the full perfection and beauty of that soul, attained by the concurrent action of "Nature" and "Grace," a character would be formed like nothing else which is visible in this world, and having a mode of action different, inasmuch as complementary to all inferior modes of action. Something of this is evident even to those who approach the subject from the point of view of physical science only. Thus Mr. Wallace observes,[307] that on his view man is to be placed "apart, as not only the head and {284} culminating point of the grand series of organic nature, but as in some degree _a new and distinct order of being_.[308] From those infinitely remote ages when the first rudiments of organic life appeared upon the earth, every plant and every animal has been subject to one great law of physical change. As the earth has gone through its grand cycles of geological, climatal, and organic progress, every form of life has been subject to its irresistible action, and has been continually but imperceptibly moulded into such new shapes as would preserve their harmony with the ever-changing universe. No living thing could escape this law of its being; none (except, perhaps, the simplest and most rudimentary organisms) could remain unchanged and live amid the universal change around it." "At length, however, there came into existence a being in whom that subtle force we term _mind_, became of greater importance than his mere bodily structure. Though with a naked and unprotected body, _this_ gave him clothing against the varying inclemencies of the seasons. Though unable to compete with the deer in swiftness, or with the wild bull in strength, _this_ gave him weapons with which to capture or overcome both. Though less capable than most other animals of living on the herbs and the fruits that unaided nature supplies, this wonderful faculty taught him to govern and direct nature to his own benefit, and make her produce food for him when and where he pleased. From the moment when the first skin was used as a covering; when the first rude spear was formed to assist in the chase; when fire was first used to cook his food; when the first seed was sown or shoot planted, a grand revolution was effected in nature, a revolution which in all the previous ages of the earth's history had had no parallel, for a being had arisen who was no longer necessarily subject to change with the changing universe, a being who was in some degree superior to nature, inasmuch as he knew how to control and regulate her action, and could {285} keep himself in harmony with her, not by a change in body, but by an advance in mind." "On this view of his special attributes, we may admit 'that he is indeed a being apart.' Man has not only escaped 'Natural Selection' himself, but he is actually able to take away some of that power from nature which before his appearance she universally exercised. We can anticipate the time when the earth will produce only cultivated plants and domestic animals; when man's selection shall have supplanted 'Natural Selection;' and when the ocean will be the only domain in which that power can be exerted." Baden Powell[309] observes on this subject: "The relation of the animal man to the intellectual, moral, and spiritual man, resembles that of a crystal slumbering in its native quarry to the same crystal mounted in the polarizing apparatus of the philosopher. The difference is not in physical nature, but in investing that nature with a new and higher application. Its continuity with the material world remains the same, but a new relation is developed in it, and it claims kindred with ethereal matter and with celestial light." This well expresses the distinction between the merely physical and the hyperphysical natures of man, and the subsumption of the former into the latter which dominates it. The same author in speaking of man's moral and spiritual nature says,[310] "The assertion in its very nature and essence refers wholly to a DIFFERENT ORDER OF THINGS, apart from and transcending any material ideas whatsoever." Again[311] he adds, "In proportion as man's _moral_ superiority is held to consist in attributes _not_ of a _material_ or corporeal kind or origin, it can signify little how his _physical_ nature may have originated." Now physical science, as such, has nothing to do with the soul of man which is hyperphysical. That such an entity exists, that the correlated {286} physical forces go through their Protean transformations, have their persistent ebb and flow outside of the world of WILL and SELF-CONSCIOUS MORAL BEING, are propositions the proofs of which have no place in this work. This at least may however be confidently affirmed, that no reach of physical science in any coming century will ever approach to a demonstration that countless modes of being, as different from each other as are the force of gravitation and conscious maternal love, may not co-exist. Two such modes are made known to us by our natural faculties only: the physical, which includes the first of these examples; the hyperphysical, which embraces the other. For those who accept revelation, a third and a distinct mode of being and of action is also made known, namely, the direct and immediate or, in the sense here given to the term, the supernatural. An analogous relationship runs through and connects all these modes of being and of action. The higher mode in each case employs and makes use of the lower, the action of which it occasionally suspends or alters, as gravity is suspended by electro-magnetic action, or the living energy of an organic being restrains the inter-actions of the chemical affinities belonging to its various constituents. Thus conscious will controls and directs the exercise of the vital functions according to desire, and moral consciousness tends to control desire in obedience to higher dictates.[312] The action of living {287} organisms depends upon and subsumes the laws of inorganic matter. Similarly the actions of animal life depend upon and subsume the laws of organic matter. In the same way the actions of a self-conscious moral agent, such as man, depend upon and subsume the laws of animal life. When a part or the whole series of these natural actions is altered or suspended by the intervention of action of a still higher order, we have then a "miracle." In this way we find a perfect harmony in the double nature of man, his rationality making use of and subsuming his animality; his soul arising from direct and immediate creation, and his body being formed at first (as now in each separate individual) by derivative or secondary creation, through natural laws. By such secondary creation, _i.e._ by natural laws, for the most part as yet unknown but controlled by "Natural Selection," all the various kinds of animals and plants have been manifested on this planet. That Divine action has concurred and concurs in these laws we know by deductions from our primary intuitions; and physical science, if unable to demonstrate such action, is at least as impotent to disprove it. Disjoined from these deductions, the phenomena of the universe present an aspect devoid of all that appeals to the loftiest aspirations of man, that which stimulates his efforts after goodness, and presents consolations for unavoidable shortcomings. Conjoined with these same deductions, all the harmony of physical nature and the constancy of its laws are preserved unimpaired, while the reason, the conscience, and the æsthetic instincts are alike gratified. We have thus a true reconciliation of science and religion, in which each gains and neither loses, one being complementary to the other. Some apology is due to the reader for certain observations and arguments which have been here advanced, and which have little in the shape of novelty to recommend them. But after all, novelty can hardly be predicated of the views here criticised and opposed. Some of these seem almost a {288} return to the "fortuitous concourse of atoms" of Democritus, and even the very theory of "Natural Selection" itself--a "survival of the fittest"--was in part thought out not hundreds but _thousands_ of years ago. Opponents of Aristotle maintained that by the accidental occurrence of combinations, organisms have been preserved and perpetuated such as final causes, did they exist, would have brought about, disadvantageous combinations or variations being speedily exterminated. "For when the very same combinations happened to be produced which the law of final causes would have called into being, those combinations which proved to be advantageous to the organism were preserved; while those which were not advantageous perished, and still perished like the minotaurs and sphinxes of Empedocles."[313] In conclusion, the Author ventures to hope that this treatise may not be deemed useless, but have contributed, however slightly, towards clearing the way for peace and conciliation and for a more ready perception, of the harmony which exists between those deductions from our primary intuitions before alluded to, and the teachings of physical science, as far, that is, as concerns the evolution of organic forms--_the genesis of species_. The aim has been to support the doctrine that these species have been evolved by ordinary _natural laws_ (for the most part unknown) controlled by the _subordinate_ action of "Natural Selection," and at the same time to remind some that there is and can be absolutely nothing in physical science which forbids them to regard those natural laws as acting with the Divine concurrence and in obedience to a creative fiat originally imposed on the primeval Cosmos, "in the beginning," by its Creator, its Upholder, and its Lord. {289} * * * * * INDEX. A. Aard-Vark, 174. Absolute creation, 252. Acanthometræ, 186. Acrodont teeth, 148. Acts formally moral, 195. Acts materially moral, 195. Adductor muscles, 79. Agassiz, Professor, 271. Aged, care of, 192. Aggregational theory, 163. Algoa Bay, cat of, 98. Allantois, 82. Amazons, butterflies of, 85. Amazons, cholera in the, 192. American butterflies, 29. American maize, 100. American monkeys, 226. Amiurus, 147. Amphibia, 109. Analogical relations, 157. Ancon sheep, 100, 103, 227. Andrew Murray, Mr., 83. Angora cats, 175. Animal's sufferings, 260. Ankle bones, 158. Annelids undergoing fission, 169, 211. Annulosa, eye of, 76. Anoplotherium, 109. Anteater, 83. Antechinus, 82. Antenna, of orchid, 56. Anthropomorphism, 258. Ape's sexual characters, 49. Apostles' Creed, 245. Appendages of lobster, 161. Appendages of Normandy pigs, 99. Appendages of turkey, 100. Appendix, vermiform, 83. Appreciation of Mr. Darwin, 10. Apteryx, 7, 70. Aqueous humour, 76. Aquinas, St. Thomas, 17, 263, 265. Archegosaurus, 135. Archeopteryx, 73. Arcturus, 193. Argyll, Duke of, 14, 276. Aristotle, 288. Armadillo, extinct kind, 110. Arthritis, rheumatic, 183. Artiodactyle foot, 109. Asa Gray, Dr., 253, 255, 261. Asceticism, 193. Ascidians, placental structure, 81. Assumptions of Mr. Darwin, 16. Astronomical objections, 136. Auditory organ, 74. Augustin, St., 17, 263, 264. Aurelius, Marcus, 206. Avian limb, 106. Avicularia, 80. Axolotl, 165. Aye-Aye, 107. Aylesbury ducks, 234. B. Backbone, 135, 162. Bacon, Roger, 266. Baleen, 40. Bamboo insect, 33. Bandicoot, 67. Bartlett, Mr. A. D., 126, 234. Bartlett, Mr. E., 192. Basil, St., 17. Bastian, Dr. H. Charlton, 115, 219, 237, 266. Bat, wing of, 64. Bates, Mr., 29, 85, 87. [Page 290] Bats, 108. Beaks, 83. Beasts, sufferings of, 260. Beauty of shell-fish, 54. Bee orchid, 55. Bird, wings of, 64. Birds compared with reptiles, 70. Bird's-head processes, 80. Birds of Paradise, 90. Birth of individual and species, 2. Bivalves, 79. Black sheep, 122. Black-shouldered peacock, 100. Bladebone, 70. Blood-vessels, 182. Blyth, Mr., 100, 181. Bones of skull, 153. Bonnet, M., 217. Borwick, Mr., 198. "Boots" of pigeons, 181. Breathing, modified power of, 99. Breeding of lions, 234. Brill, 37. Broccoli, variety of, 100. Bryozoa, 81. Buchner, Dr., 273. Budd, Dr. W., 183. Buffon, 217. Bull-dog's instinct, 260. Burt, Prof. Wilder, 180, 184. Butterflies, 29. Butterflies, Amazonian, 85. Butterflies, American, 29. Butterflies of Indian region, 83. Butterflies, tails of, 85. Butterfly, Leaf, 31. C. Cacotus, 149. Cæcum, 83. Calamaries, 77. Cambrian deposits, 137. Cape ant-eater, 174. Care of aged, 192. Carinate birds, 70. Carnivora, 68. Carnivorous dentition, 110. Carp fishes, 146. Carpal bones, 106, 178. Carpenter, Dr., 115. Carpus, 177, 178. Cases of conscience, 201. Cassowary, 70. Catasetum, 56. Causes of spread of Darwinism, 10. Cebus, 226. Celebes, butterflies of, 85. Centetes, 148. Centipede, 66, 159. Cephalopoda, 74. Ceroxylus laceratus, 36. Cetacea, 42, 83, 105, 108, 174. Chances against few individuals, 57. Characinidæ, 146. Cheirogaleus, 158. Chetahs, 234. Chickens, mortality of hybrids, 124. Chioglossa, 165. Chiromys, 107. Cholera, 192. Choroid, 76. Chronic rheumatism, 183. Circumcision, 212. Clarias, 146. Climate, effects of, 98. Climbing plants, 107. Clock-thinking illustration, 249. Cobra, 50. Cockle, 79. Cod, 39. Colloidal matter, 266. Conceptions, symbolic, 251. Connecticut footsteps, 131. Connecting links, supposed, 107. Conscience, cases of, 201. Conscientious Papuan, 197. Cope, Professor, 71, 130. Coracoid, of birds and reptiles, 70. Cornea, 77. Cornelius à Lapide, 265. Correlation, laws of, 173. Corti, fibres of, 53, 279. Coryanthes, 56. Costa, M., 88. Cranial segments, 172. Creation, 245, 252. Creator, 15, 252. Creed, Apostles', 245. Crocodile, 43. Croll, Mr., 137. Crustacea, 79, 160. Cryptacanthus, 146. Crystalline matter, 266. Crystals of snow, 186. Cuttle-fishes, 74, 75. Cuvier, 109. Cyprinoids, 146. Cytheridea, 79. [Page 291] D. Dana, Professor, 149. Darwin, Mr. Charles, 2, 10, 12, 14-21, 23, 27, 34, 35, 43, 45, 47, 48, 55-57, 59, 65, 88, 94, 98-100, 107, 118-126, 129, 138, 142, 145, 149, 150, 181, 188-190, 196, 208, 209, 214-216, 218, 223, 233, 234, 252, 254, 258, 259, 275, 276. Datura tatula, 101. Delhi, days at, 98. Delpino, Signor, 212, 213, 215. Democritus, 217, 275, 288. Density of air for breathing, 99. Dentition, carnivorous, 110. Derivation, 238. Derivative creation, 252, 282. Design, 259. Devotion, 193. Dibranchiata, 74. Difficulties of problem of specific origin, 1. Digits, supernumerary, 122, 181. Digits, turtle's, 106. Dimorphodon, 71. Dinornis, 70. Dinosauria, 71. Diseased pelvis, 182. Dissemination of seeds, 65. Doris, 170. Dotheboys' Hall, 272. Dragon, the flying, 64, 158. Dragon-fly, 77. Droughts, 25. Duck-billed platypus, 175. Dugong, 41, 175. Duke of Argyll, 14, 276. Dyspepsia, 201. E. Ear, 74. Ear, formation of, 51. Early specialization, 111. Echinodermata, 44. Echinoidea, 44. Echinops, 148. Echinorhinus, 172. Echinus, 43. Economy, Fuegian political, 192. Eczema, 183. Edentata, 174. Egyptian monuments, 138. Elasmobranchs, 140. Elbow and knee affections, 183. Empedocles, 288. Eocene ungulata, 110. Eolis, 170. Equus, 97. Ericulus, 148. Ethics, 188. Eudes Deslongchamps, 99. Eurypterida, 141, 171. Eutropius, 147. Everett, Rev. R., 98. Evolution requires geometrical increase of time, 139. Eye, 76. Eye, formation of, 51. Eye of trilobites, 135. F. Fabre, M., 46. Feather-legged breeds, 181. Feejeans, 199. Fertilization of orchids, 55. "Fiat justitia, ruat coelum," 195. Fibres of Corti, 53, 279. Final misery, 194. Finger of Potto, 105. Fish, flying, 64. Fishes, fresh-water, 145. Fishes, thoracic and jugular, 39, 140. Fixity of position of limbs, 39. Flat-fishes, 37, 166. Flexibility of bodily organization, degrees of, 119. Flexibility of mind, 267. Flies, horned, 93. Flight of spiders, 65. Flounder, 37. Flower, Professor, 163, 232, 283. Fly, orchid, 55. Flying-dragon, 64, 158. Flying fish, 64. Foetal teeth of whales, 7. Food, effects on pigs, 99. Footsteps of Connecticut, 131. Foraminifera, 186. Formally moral acts, 195. Formation of eye and ear, 51. Forms, substantial, 186, 272. Four-gilled Cephalopods, 76. Fowls, white silk, 122. French theatrical audience, 198. Fresh-water fishes, 145. Frogs, Chilian and European, 149. Fuego, Terra del, 192. [Page 292] G. Galago, 158. Galaxias, 147. Galeus vulgaris, 172. Galton, Mr. F., 97, 113, 228. Gascoyen, Mr., 182. Gavials, 43. Gegenbaur, Prof., 176-178. Gemmules, 208. Generative system, its sensitiveness, 235. Genesis of morals, 201. Geographical distribution, 144. Geographical distribution explained by Natural Selection, 6. Geometrical increments of time, 139. Geotria, 147. Giraffe, neck of, 24. Gizzard-like stomach, 83. Glacial epoch, 150. Glyptodon, 110. Godron, Dr., 101. Goose, its inflexibility, 119. Göppert, Mr., 101. Gould, Mr., 88. Grasshopper, Great Shielded, 89. Gray, Dr. Asa, 253, 255, 261. Great Ant-eater, 83. Great Salamander, 172. Great Shielded Grasshopper, 89. Greyhounds in Mexico, 99. Greyhounds, time for evolution of, 138. Guinea-fowl, 120. Guinea-pig, 126. Günther, Dr., 145, 146, 172. H. Hairless Dogs, 174, 175. Hamilton, Sir Wm., 267. Harmony, musical, 54, 279. Heart in birds and reptiles, 158. Hegel, 217. Heliconidæ, 29. Hell, 194. Heptanchus, 172. Herbert Spencer, Mr., 20, 28, 67, 72, 163-166, 168, 170-172, 184, 187, 202, 203, 205, 218, 228, 245, 246, 248, 251. Hessian flies, 170. Heterobranchus, 146. Hewitt, Mr., 124, 181. Hexanchus, 172. Hipparion, 97, 134. Homogeny, 158. Homology, bilateral or lateral, 156, 164. Homology, meaning of term, 7, 156. Homology, serial, 159. Homology, vertical, 165. Homoplasy, 159. Honey-suckers, 90. Hood of cobra, 50. Hook-billed ducks, 100. Hooker, Dr., 150. Horned flies, 93. Horny plates, 40, 42. Horny stomach, 83. Human larynx, 54, 278. Humphry, Professor, 163. Hutton, Mr. R. Holt, 202, 203. Huxley, Professor, 67-69, 71, 72, 95, 103, 109, 130, 131, 137, 141, 163, 172, 173, 231, 247, 273. Hybrids, mortality of, 124. Hydrocyonina, 146. Hyperphysical action, 253. Hyrax, 179. I. Ichthyopsida, 109. Ichthyosaurus, 78, 106, 132, 177. Ichthyosis, 183. Iguanodon, 71. Illegitimate symbolic conceptions, 251. Illustration by clock-thinking, 249. Imaginal disks, 46, 170. Implacental mammals, 67, 68. Independent origins, 152. Indian butterfly, 30. Indian region's butterflies, 83. Indians and cholera, 192. Individual, meaning of word, 2. Infirm, care of, 192. Influence, local, 83. Insect, walking-leaf, 35. Insects, walking-stick and bamboo, 33. Insectivora, 68. Insectivorous mammals, 148. Insectivorous teeth, 68. Instinct of bull-dog, 260. Intermediate forms, 128. Intuitions, primary, 251. Irregularities in blood-vessels, 182. Isaria felina, 115. [Page 293] J. Japanned Peacock, 100. Jews, 212. Joints of backbone, 157, 162. Jugular fishes, 39, 141. Julia Pastrana, 174. K. Kallima inachis, 31. Kallima paralekta, 31. Kangaroo, 42, 67. Kowalewsky, 81. Knee and elbow affections, 183. Kölliker, Professor, 104. L. Labyrinthici, 146. Labyrinthodon, 104, 134. Lamarck, 3. Lankester, Mr. Ray, 152, 158. Larynx of kangaroo, 42. Larynx of man, 54, 278. Lateral homology, 164. Laws of correlation, 173. Leaf butterfly, 31. Legitimate symbolic conceptions, 251. Lens, 76. Lepidosteus, 172. Lepra, 183. Lewes, Mr. G. H., 94, 212, 214, 216. Lewis, St., 206. Lewis XV., 206. Lewis XVI., 206. Limb genesis, 176. Limb muscles, 180. Limbs, fixity of position of, 39. Limbs of lobster, 161. Links, supposed connecting, 107. Lions, breeding, 234. Lions, diseased pelvis, 182. Llama, 109. Local influences, 83. Lobster, 160. Long-tailed bird of Paradise, 91. Lubbock, Sir John, 193, 204. Lyell Sir, Charles, on dogs, 99, 106. M. Machairodus, 110. Macrauchenia, 109. Macropodidæ, 69. Macroscelides, 68. Madagascar, 148, 152. Magnificent Bird of Paradise, 93. Maize, American, 100. Mammals, 67. Mammary gland of kangaroo, 42. Mammary gland, origin of, 47. Man, origin of, 277. Man reveals God, 267. Man, voice of, 54. Manatee, 41, 175. Manchamp breed of sheep, 100. Manis, 175. Man's larynx, 54. Many simultaneous modifications, 57. Marcus Aurelius, 206. Martineau, Mr. James, 200, 245. Mastacembelus, 145. Materially moral acts, 195. Matter, crystalline and colloidal, 266. Meaning of word "individual," 2. Meaning of word "species," 2. Mechanical theory of spine, 164. Mediterranean oyster, 88, 98. Meehan, Mr., 88. Mexico, dogs in, 99. Mill, John Stuart, 15, 189, 193, 194. Mimicry, 8, 29. Miracle, 287. Molars, 111. Mole, 176. Molière, 230. Mombas, cats at, 98. Monkeys, American, 226. Monster proboscis, 123. Moral acts, 195. Mordacia, 147. Murphy, Mr. J. J., 52, 53, 76, 103, 114, 115, 137, 185, 221, 276, 281. Murray, Mr. Andrew, 83. Mus delicatulus, 82. Muscles of limbs, 180. Mussel, 79. Myrmecophaga, 83. N. Nasalis, Semnopithecus, 139. Nathusius, 99. Natural Selection, shortly stated, 5. Naudin, M. C., 101. Nautilus, 76. Nebular evolution, 273. Neck of giraffe, 24. Newman, the Rev. Dr., 260, 268, 270, 286. [Page 294] New Zealand crustacea, 149. New Zealand fishes, 147. Niata cattle, 100. Nile fishes, 146. Normandy pig, 99. North American fish, 147 Nycticebus, 179. O. Object of book, 5. Objections from astronomy, 136. Octopods, 77. Offensive remarks of Prof. Vogt, 13. Old, care of the, 192. Old Fuegian women, 192. Omygena exigua, 115. Ophiocephalus, 146. Optic lobes of pterodactyls, 71. Orchids, 92. Orchids, Bee, &c., 55. Organ of hearing, 74. Organ of sight, 76. Organic polarities, 185. Origin of man, 277. Orioles, 90. Ornithoptera, 84. Ornithorhynchus, 175. Orthoceratidæ, 170. Orycteropus, 174. Ostracods, 79. Ostrich, 70. Otoliths, 74. Outlines of butterflies' wings, 86. Owen, Professor, 74, 102, 123, 217, 238, 274. Oyster of Mediterranean, 88, 98. Oysters, 79. P. Paget, Mr. J., 182. Palæotherium, 109. Pallas, 125. Pangenesis, 19, 208. Pangolin, 175. Papilio Hospiton, 85. Papilio Machaon, 85. Papilio Ulysses, 84. Papilionidæ, 83. Papuan morals, 197, 198. Parthenogenesis, 217. Passiflora gracilis, 107. Pastrana, Julia, 174. Pathological polarities, 184. Pavo nigripennis, 100. Peacock, black shouldered, 100. Peacock, inflexibility of, 119. Pedicellariæ, 44. Pelvis, diseased, 182. Pendulous appendages of turkey, 100. Perameles, 68. Periophthalmus, 146. Perissodactyle ungulates, 109. Permian, jugular fish, 141. Perodicticus, 105, 179. Phalangers, 67. Phasmidæ, 89. Phyllopods, 79. Physical actions, 253. "Physiological units," 168, 218. Pigeons' "boots," 181. Placental mammals, 67. Placental reproduction, 81. Plants, tendrils of, 107. Plates of baleen, 40. Platypus, 175. Pleiades, 193. Plesiosaurus, 106, 133, 178. Pleurodont dentition, 148. Pleuronectidæ, 37, 166. Plotosus, 147. Poisoning apparatus, 66. Poisonous serpents, 50. Polarities, organic, 184, 185. Political economy, Fuegian, 192. Polyzoa, 80, 81. Pompadour, Madame de, 206. Poppy, variety of, 101. Porcupine, 175. Porto Santo rabbit, 100, 122. Potto, 105, 179. Pouched beasts, 67. Powell, the Rev. Baden, 259, 261, 285. Premolars, 111. Prepotency, 124. Primary intuitions, 251. Primitive man, 204. Problem of origin of kinds, 1. Proboscis monkey, 139. Proboscis of ungulates, 123. Processes, bird's-head, 80. Psettus, 146. Psoriasis, 183. Pterodactyles, compared with birds, 70. Pterodactyles, wing of, 64. Puccinia, 115. Purpose, 259. [Page 295] Q. Quasi-vertebral theory of skull, 172. R. Rabbit of Porto Santo, 100, 122. Radial ossicle, 176. Rarefied air, effect on dogs, 99. Rattlesnake, 49, 50. Red bird of Paradise, 92. Relations, analogical, 157. Relations, homological, 156. Reptiles compared with birds, 70. Retina, 76. Retrieving, virtue a kind of, 189, 205. Reversion, cases of, 122. Rhea, 70. Ribs of Cetacea and Sirenia, 41. Ribs of flying-dragon, 64, 158. Richardson's figures of pigs, 99. Roger Bacon, 266. Rudimentary structures, 7, 102. S. Sabre-toothed tiger, 110. St. Augustin, 17, 263-265. St. Basil, 17. St. Hilaire, M., 179. St. Thomas Aquinas, 17, 263, 265. Salamander, great, 172. Salter, Mr., 124. Salvia officinalis, 213. Salvia verticillata, 213. Scapula of birds and reptiles, 70. Schreber, 13. Sclerotic, 76. Scorpion, sting of, 66. Seals, 83. Sea squirts, 81. Seeds, dissemination of, 65. Seeley, Mr., on pterodactyles, 71. Segmentation of skull, 172. Segmentation of spine, 171. Segments, similar, 160. Self-existence, 252. Semnopithecus, 139. Sense, organ of, 51, 69, 74, 76. Sensitiveness of generative system, 235. Sepia, 77. Serpents, poisonous, 50. Sexual characters of apes, 49. Sexual selection, 48. Sharks, 83. Shell-fish, beauty of, 54. Shells of oysters, 88, 98. Shielded grasshopper, 89. Silurian strata, 140, 142. Simultaneous modifications, 57. Sirenia, 42 Sir John Lubbock, 198, 204. Sir William Thomson, 136. Sitaris, 46. Six-shafted bird of Paradise, 90. Skull bones, 153. Skull segments, 172. Sloth, windpipe of, 82. Smithfield, wife-selling in, 198. Snow, crystals of, 186. Sole, 37. Solenodon, 148. Species, meaning of word, 2. Spelerpes, 165. Spencer, see Herbert Spencer. Spider orchid, 55. Spiders, flight of, 65. Spine of Glyptodon, 110. Spine, segmentation of, 172. Squalidæ, 38. Squilla, 160. Sterility of hybrids, 125. Stings, 66. Straining action of baleen, 41. Struthious birds, 70, 151. Sturgeon, 171. Suarez, 18, 263. Substantial forms, 186, 272. Sufferings of beasts, 260. Supernatural action, 252. Supernatural action not to be looked for in nature, 15. Supernumerary digits, 122, 181. Syllis, 169, 211. Symbolic conceptions, 251. Symmetrical diseases, 182. Syphilitic deposits, 183. T. Tadpole's beak, 83. Tails of butterflies, 85. Tapir, 123, 134. Tarsal bones, 159, 198. Teeth of Cetacea, 83. Teeth of Insectivora, 68. Teeth of kangaroo and Macroscelides, 69. Teeth of seals, 83. Teeth of sharks, 83. [Page 296] Teleology and evolution compatible, 273. Tendrils of climbing plants, 107. Tenia echinococcus, 170. Teratology, 173. Tetragonopterina, 146. Thomson, Sir William, 136. Thoracic fishes, 39. Thorax of crustaceans, 79. Thylacine, 67. Tierra del Fuego, 192. Tiger, sabre-toothed, 110. Time required for evolution, 128. Tope, 172. Trabeculæ cranii, 172. Transitional forms, 128. Transmutationism, 242. Trevelyan, Sir J. Peacock, 100. Trilobites, 135, 141, 171. Tunicaries, 81. Turbot, 37. Turkey, effects of climate on, 100. Turkish dog, 45. Two-gilled cephalopods, 76. Type, conformity to, 241. U. Umbilical vesicle, 82. Ungulata, 25, 109. Ungulata eocene, 110. Units, physiological, 168, 218. Unknowable, the, 245. Upper Silurian strata, 140, 142. Urotrichus, 68. V. Variability, different degrees of, 119. Vermiform appendix, 83. Vertebræ of skull, 172. Vertebral column, 162, 171. Vertebrate limbs, 38, 163. Vertical homology, 165. Vesicle, umbilical, 82. "Vestiges of Creation," 3. View here advocated, 5. Vitreous humour, 76. Vogt, Professor, 12, 273. Voice of man, 54. Voltaire, 230. W. Wagner, J. A., 13. Wagner, Nicholas, 170. Walking leaf, 35. Walking-stick insect, 33. Wallace, Mr. Alfred, 2, 10, 26, 29, 30, 32, 35, 36, 54, 83, 84, 87, 89, 90, 103, 117, 191, 197, 226, 274, 281-283. Weaver fishes, 39. Weitbrecht, 179. Whale, foetal teeth of, 7. Whale, mouth of, 40. Whalebone, 40. Whales, 78. White silk fowls, 122. Wife selling, 198. Wild animals, their variability, 120. Wilder, Professor Burt, 180, 184. Windpipe, 82. Wings of bats, birds, and pterodactyles, 64, 130. Wings of birds, origin of, 106. Wings of butterflies, outline of, 86. Wings of flying-dragon, 64, 158. Wings of humming-bird, 157. Wings of humming-bird hawk moth, 157. Wings of insects, 65. Wombat, 83. Women, old Fuegian, 192. Worms undergoing fission, 169, 211. Wyman, Dr. Jeffries, 185. Y. York Minster, a Fuegian, 197. Z. Zebras, 134. Zoological Gardens, Superintendent of, 126. R. CLAY, SONS, AND TAYLOR, PRINTERS, LONDON. * * * * * Notes [1] In the last edition of the "Origin of Species" (1869) Mr. Darwin himself admits that "Natural Selection" has not been the exclusive means of modification, though he still contends it has been the most important one. [2] See Mr. Wallace's recent work, entitled "Contributions to the Theory of Natural Selection," where, at p. 302, it is very well and shortly stated. [3] "Natural Selection" is happily so termed by Mr. Herbert Spencer in his "Principles of Biology." [4] Biology is the science of life. It contains zoology, or the science of animals, and botany, or that of plants. [5] For very interesting examples, see Mr. Wallace's "Malay Archipelago." [6] See Müller's work, "Für Darwin," lately translated into English by Mr. Dallas. Mr. Wallace also predicts the discovery, in Madagascar, of a hawk-moth with an enormously long proboscis, and he does this on account of the discovery there of an orchid with a nectary from ten to fourteen inches in length. See _Quarterly Journal of Science_, October 1867, and "Natural Selection," p. 275. [7] "Lectures on Man," translated by the Anthropological Society, 1864, p. 229. [8] Ibid. p. 378. [9] See Fifth Edition, 1869, p. 579. [10] _The Rambler_, March 1860, vol. xii. p. 372. [11] "In primâ institutione naturæ non quæritur miraculum, sed quid natura rerum habeat, ut Augustinus dicit, lib. ii. sup. Gen. ad lit. c. l." (St. Thomas, Sum. I^æ. lxvii. 4, ad 3.) [12] "Hexaem." Hom. ix. p. 81. [13] Suarez, Metaphysica. Edition Vivés. Paris, 1868. Vol. I. Disputatio xv. § 2. [14] "Pangenesis" is the name of the new theory proposed by Mr. Darwin, in order to account for various obscure physiological facts, such, _e.g._, as the occasional reproduction, by individuals, of parts which they have lost; the appearance in offspring of parental, and sometimes of remote ancestral, characters, &c. It accounts for these phenomena by supposing that every creature possesses countless indefinitely-minute organic atoms, termed "gemmules," which atoms are supposed to be generated in every part of every organ, to be in constant circulation about the body, and to have the power of reproduction. Moreover, atoms from every part are supposed to be stored in the generative products. [15] "Animals and Plants under Domestication," vol. ii. p. 192. [16] "Animals and Plants under Domestication," vol. ii. p. 414. [17] "Origin of Species," 5th edit., 1869, p. 110. [18] Ibid. p. 111. [19] Ibid. p. 227. [20] The order _Ungulata_ contains the hoofed beasts; that is, all oxen, deer, antelopes, sheep, goats, camels, hogs, the hippopotamus, the different kinds of rhinoceros, the tapirs, horses, asses, zebras, quaggas, &c. [21] The elephants of Africa and India, with their extinct allies, constitute the order _Proboscidea_, and do not belong to the Ungulata. [22] See "Natural Selection," pp. 60-75. [23] "Principles of Biology," vol. i. p. 122. [24] See "Natural Selection," chap. iii. p. 45. [25] Loc. cit. p. 80. [26] Ibid. p. 59. [27] Loc. cit. p. 64. [28] "Origin of Species," 5th edit. p. 104. [29] "Animals and Plants under Domestication," vol. ii. p. 351. [30] Loc. cit. pp. 109, 110. [31] Heredity is the term used to denote the tendency which there is in offspring to reproduce parental features. [32] Loc. cit. p. 64. [33] Loc. cit. p. 60. [34] The term "Vertebrata" denotes that large group of animals which are characterized by the possession of a spinal column, commonly known as the "backbone." Such animals are ourselves, together with all beasts, birds, reptiles, frogs, toads, and efts, and also fishes. [35] It is hardly necessary to observe that these "sea-snakes" have no relation to the often-talked-of "sea-serpent." They are small, venomous reptiles, which abound in the Indian seas. [36] "Origin of Species," 5th edit., 1869, p. 179. [37] "Origin of Species," 5th edit., p. 532. [38] Mr. A. D. Bartlett, of the Zoological Society, informs me that at these periods female apes admit with perfect readiness the access of any males of different species. To be sure this is in confinement; but the fact is, I think, quite conclusive against any such sexual selection in a state of nature as would account for the local coloration referred to. [39] Mr. Darwin, in the last (fifth) edition of "Natural Selection," 1869, p. 102, admits that all sexual differences are not to be attributed to the agency of sexual selection, mentioning the wattle of carrier pigeons, tuft of turkey-cock, &c. These characters, however, seem less inexplicable by sexual selection than those given in the text. [40] I am again indebted to the kindness of Mr. A. D. Bartlett, amongst others. That gentleman informs me that, so far from any mental emotion being produced in rabbits by the presence and movements of snakes, that he has actually seen a male and female rabbit satisfy the sexual instinct in that presence, a rabbit being seized by a snake when _in coitu_. [41] "Habit and Intelligence," vol. i. p. 319. [42] The reader may consult Huxley's "Lessons in Elementary Physiology," p. 204. [43] "Natural Selection," p. 350. [44] Bivalve shell-fish are creatures belonging to the oyster, scallop, and cockle group, _i.e._ to the class Lamellibranchiata. [45] The attempt has been made to explain these facts as owing to "manner and symmetry of growth, and to colour being incidental on the chemical nature of the constituents of the shell." But surely beauty depends on some such matters in _all_ cases! [46] It has been suggested in opposition to what is here said, that there is no real resemblance, but that the likeness is "_fanciful!_" The denial, however, of the fact of a resemblance which has struck so many observers, reminds one of the French philosopher's estimate of facts hostile to his theory--"Tant pis pour les faits!" [47] Fifth Edition, p. 236. [48] Mr. Smith, of the Entomological department of the British Museum, has kindly informed me that the individuals intermediate in structure are very few in number--not more than five per cent.--compared with the number of distinctly differentiated individuals. Besides, in the Brazilian kinds these intermediate forms are wanting. [49] By accidental variations Mr. Darwin does not, of course, mean to imply variations really due to "chance," but to utterly indeterminate antecedents. [50] "Origin of Species," 5th edition, p. 235. [51] _I.e._ warm-blooded animals which suckle their young, such as apes, bats, hoofed beasts, lions, dogs, bears, weasels, rats, squirrels, armadillos, sloths, whales, porpoises, kangaroos, opossums, &c. [52] "Journal of Anatomy and Physiology" (1868), vol. ii. p. 139. [53] See "Ann. and Mag. of Nat. Hist." for August 1870, p. 140. [54] See "Proceedings of the Royal Institution," vol. v. part iv. p. 278: Report of a Lecture delivered February 7, 1868. Also "Quarterly Journal of the Geological Society," February 1870: "Contributions to the Anatomy and Taxonomy of the Dinosauria." [55] "Proceedings of Geological Society," November 1869, p. 38. [56] The archeopteryx of the oolite has the true carinate shoulder structure. [57] "Proceedings of the Royal Institution," vol. v. p. 279. [58] This remark is made without prejudice to possible affinities in the direction of the Ascidians,--an affinity which, if real, would be irrelevant to the question here discussed. [59] "Lectures on the Comp. Anat. of the Invertebrate Animals," 2nd edit. 1855, p. 619; and Todd's "Cyclopædia of Anatomy," vol. i. p. 554. [60] See "Habit and Intelligence," vol. i. p. 321. [61] A view recently propounded by Kowalewsky. [62] "Natural Selection," p. 167. [63] "Natural Selection," p. 173. [64] Ibid. p. 177. [65] "Malay Archipelago," vol. i. p. 439. [66] "Natural Selection," p. 177. [67] "Origin of Species," 5th edition, p. 166. [68] Vol. ii. p. 280. [69] See "Natural Selection," p. 64. [70] The italics are not Mr. Wallace's. [71] "Malay Archipelago," vol. ii. p. 150; and "Natural Selection," p. 104. [72] See "Malay Archipelago," vol. ii. chap. xxxviii. [73] Loc. cit. p. 314. [74] _Fortnightly Review_, New Series, vol. iii (April 1868), p. 372. [75] "Lay Sermons," p. 339. [76] "Hereditary Genius, an Inquiry into its Laws," &c. By Francis Galton, F.R.S. (London: Macmillan.) [77] "Animals and Plants under Domestication," vol. i. p. 37. [78] Ibid. p. 47. [79] Ibid. p. 52. [80] Carpenter's "Comparative Physiology," p. 987, quoted by Mr. J. J. Murphy, "Habit and Intelligence," vol. i. p. 171. [81] "Animals and Plants under Domestication," vol. i. p. 72. [82] Ibid. p. 76. [83] "Animals and Plants under Domestication," vol. i. p. 71. [84] Ibid. p. 114. [85] Quoted, Ibid. p. 274. [86] Ibid. p. 324. [87] Ibid. p. 322. [88] Ibid. vol. ii. p. 414. [89] Proc. Zool. Soc. of London, April 24, 1860. [90] "Animals and Plants under Domestication," vol. i. p. 291. [91] Extracted by J. J. Murphy, vol. i. p. 197, from the _Quarterly Journal of Science_, of October 1867, p. 527. [92] "Anatomy of Vertebrates," vol. iii. p. 795. [93] Ibid. p. 807. [94] "Animals and Plants under Domestication," vol. ii. p. 318. [95] "Habit and Intelligence," vol. i. p. 344. [96] See Dec. 2, 1869, vol. i. p. 132. [97] "Über die Darwin'sche Schöpfungstheorie:" ein Vortrag, von Kölliker; Leipzig, 1864. [98] See "Lay Sermons," p. 342. [99] "Anatomy of the Lemuroidea." By James Murie, M.D., and St. George Mivart. Trans. Zool. Soc., March 1866, p. 91. [100] "Principles of Geology," last edition, vol. i. p. 163. [101] _Quarterly Journal of Science_, April 1866, pp. 257-8. [102] "Habit and Intelligence," vol. i. p. 178. [103] This animal belongs to the order Primates, which includes man, the apes, and the lemurs. The lemurs are the lower kinds of the order, and differ much from the apes. They have their head-quarters in the Island of Madagascar. The aye-aye is a lemur, but it differs singularly from all its congeners, and still more from all apes. In its dentition it strongly approximates to the rodent (rat, squirrel, and guinea-pig) order, as it has two cutting teeth above, and two below, growing from permanent pulps, and in the adult condition has no canines. [104] _North British Review_, New Series, vol. vii., March 1867, p. 282. [105] "Habit and Intelligence," vol. i. p. 75. [106] "Habit and Intelligence," vol. i. p. 202. [107] "Comparative Physiology," p. 214, note. [108] See _Nature_, June and July 1870, Nos. 35, 36, and 37, pp. 170, 193, and 219. [109] "Natural Selection," p. 293. [110] "Animals and Plants under Domestication," vol. i. pp. 289-295. [111] "Origin of Species," 5th edition, 1869, p. 45. [112] Ibid. p. 13. [113] "Animals and Plants under Domestication," vol. i. p. 115. [114] Ibid. vol. i. p. 114. [115] Ibid. vol. i. p. 243. [116] Ibid. vol. ii. p. 361. [117] Ibid. vol. ii. p. 16. [118] "Animals and Plants under Domestication," vol. ii. p. 57. [119] This has been shown by my late friend, Mr. H. N. Turner, jun., in an excellent paper by him in the "Proceedings of the Zoological Society for 1849," p. 147. The untimely death, through a dissecting wound, of this most promising young naturalist, was a very great loss to zoological science. [120] "Animals and Plants under Domestication," vol. ii. p. 189. [121] "Origin of Species," 5th edition, 1839, p. 115. [122] Ibid. p. 322. [123] Ibid. p. 314. [124] "Animals and Plants under Domestication," vol. ii. p. 104. [125] _North British Review_, New Series, vol. vii., March 1867, p. 317. [126] "Origin of Species," 5th edition, 1869, p. 212. [127] See also the _Popular Science Review_ for July 1868. [128] A bird with a keeled breast-bone, such as almost all existing birds possess. [129] "Anatomy of Vertebrates," vol. iii. p. 792. [130] Ibid. p. 793. [131] As a tadpole is the _larval form_ of a frog. [132] As Professor Huxley, with his characteristic candour, fully admitted in his lecture on the Dinosauria before referred to. [133] "Transactions of the Geological Society of Glasgow," vol. iii. [134] "Origin of Species," 5th edition, p. 354. [135] See his address to the Geological Society, on February 19, 1869. [136] See _Nature_, vol. i. p. 399, February 17, 1870. [137] Ibid. vol. i. p. 454. [138] "Habit and Intelligence," vol. i. p. 344. [139] "Habit and Intelligence," vol. i. p. 345. [140] "Origin of Species," 5th edition, p. 353. [141] "Origin of Species," 5th edition, p. 381. [142] "Origin of Species," 5th edition, 1869, p. 463. [143] See his Catalogue of Acanthopterygian Fishes in the British Museum, vol. iii. p. 540. [144] Proc. Zool. Soc. 1867, p. 102, and Ann. Mag. of Nat. Hist. vol. xx. p. 110. [145] See Catalogue, vol. iii. p. 469. [146] Ibid. vol. v. p. 311. [147] Ibid. p. 345. [148] Ibid. p. 13. [149] Ibid. p. 21. [150] See Catalogue, vol. v. p. 24. [151] Ibid. p. 52. [152] Ibid. p. 109. [153] Ibid. vol. vi. 208. [154] Ibid. vol. viii. p. 507. [155] Ibid. p. 509. [156] Proc. Zool. Soc. 1868, p. 482 [157] "Origin of Species," 5th edition, 1869, p. 454. [158] "Origin of Species," 5th edition, p. 459. [159] See Ann. and Mag. of Nat. Hist., July 1870, p. 37. [160] Professor Huxley's Lectures on the Elements of Comp. Anat. p. 184. [161] For an enumeration of the more obvious homological relationships see Ann. and Mag. of Nat. Hist. for August 1870, p. 118. [162] See Ann. and Mag, of Nat. Hist., July 1870. [163] Treatise on the Human Skeleton, 1858. [164] Hunterian Lectures for 1864. [165] Linnæan Transactions, vol. xxv. p. 395, 1866. [166] Hunterian Lectures for 1870, and Journal of Anat. for May 1870. [167] See a Paper on the "Axial Skeleton of the Urodela," in Proc. Zool. Soc. 1870, p. 266. [168] Just as Button's superfluous lament over the unfortunate organization of the sloth has been shown, by the increase of our knowledge, to have been uncalled for and absurd, so other supposed instances of non-adaptation will, no doubt, similarly disappear. Mr. Darwin, in his "Origin of Species," 5th edition, p. 220, speaks of a woodpecker (_Colaptes campestris_) as having an organization quite at variance with its habits, and as never climbing a tree, though possessed of the special arboreal structure of other woodpeckers. It now appears, however, from the observations of Mr. W. H. Hudson, C.M.Z.S., that its habits are in harmony with its structure. See Mr. Hudson's third letter to the Zoological Society, published in the Proceedings of that Society for March 24, 1870, p. 159. [169] Dr. Cobbold has informed the Author that he has never observed a planaria divide spontaneously, and he is sceptical as to that process taking place at all. Dr. H. Charlton Bastian has also stated that, in spite of much observation, he has never seen the process in _vorticella_. [170] Professor Huxley's Hunterian Lecture, March 16, 1868. [171] Ibid. March 18. [172] "Principles of Biology," vol. ii. p. 105. [173] "Principles of Biology," vol. ii. p. 203. [174] Quoted by H. Stannius in his "Handbuch der Anatomie der Wirbelthiere," Zweite Auflage, Erstes Buch, § 7, p. 17. [175] In his last Hunterian Course of Lectures, 1869. [176] "The Science of Abnormal Forms." [177] "Animals and Plants under Domestication," vol. ii. p. 322; and "Origin of Species," 5th edition, 1869, p. 178. [178] A remarkable woman exhibited in London a few years ago. [179] "Animals and Plants under Domestication," vol. ii. p. 328. [180] "Ueber das Gliedmaassenskelet der Enaliosaurier, Jenaischen Zeitschrift," Bd. v. Heft 3, Taf. xiii. [181] In his work on the Carpus and Tarsus. [182] An excellent specimen displaying this resemblance is preserved in the Museum of the Royal College of Surgeons. [183] Phil. Trans. 1867, p. 353. [184] Proc. Zool. Soc. 1865, p. 255. [185] Ibid. p. 351. [186] "Hist. Générale des Anomalies," t. i. p. 228. Bruxelles, 1837. [187] Nov. Comment. Petrop. t. ix. p. 269. [188] Read on June 2, 1868, before the Massachusetts Medical Society. See vol. ii. No. 3. [189] "Animals and Plants under Domestication," vol. ii. p. 322. [190] "Lectures on Surgical Pathology," 1853, vol. i. p. 18. [191] "Lectures on Surgical Pathology," 1853, vol. i. p. 22. [192] See "Medico-Chirurgical Transactions," vol. xxv. (or vii. of 2nd series), 1842, p. 100, Pl. III. [193] Med.-Chirurg. Trans, vol. xxv. (or vii. of 2nd series), 1842, p. 122. [194] See _Boston Medical and Surgical Journal_ for April 5, 1866, vol. lxxiv. p. 189. [195] "Principles of Biology," vol. i. p. 180. [196] See the "Proceedings of the Boston Society of Natural History," vol. xi. June 5, 1867. [197] "Habit and Intelligence," vol. i. p. 75. [198] Ibid. p. 112. [199] Ibid. p. 170. [200] "Habit and Intelligence," vol. i. p. 229. [201] It is hardly necessary to say that the Author does not mean that there is, in addition to a real objective crystal, another real, objective separate thing beside it, namely the "force" directing it. All that is meant is that the action of the crystal in crystallizing must be _ideally_ separated from the crystal itself, not that it is _really_ separate. [202] "Origin of Species," 5th edition, 1869, p. 577. [203] Vol. ii. p. 122. [204] "Animals and Plants under Domestication," vol. i p. 295. [205] "Natural Selection," p. 350. [206] "Animals and Plants under Domestication," vol. ii. [207] See 2nd edition, vol. i. p. 214. [208] Page 103. [209] I have not the merit of having noticed this inconsistency; it was pointed out to me by my friend the Rev. W. W. Roberts. [210] Vol. i. p. 215. [211] "Malay Archipelago," vol. ii. p. 365. [212] "The Origin of Civilization and the Primitive Condition of Man," p. 261. Longmans, 1870. [213] "Primitive Man," p. 248. [214] "Fiji and the Fijians," vol. i. p. 183. [215] "Essays," Second Series, vol. ii. p. 13. [216] See No. 117, July 1869, p. 272. [217] _Macmillan's Magazine_, No. 117, July 1869. [218] "Animals and Plants under Domestication," vol. ii. p. 403. [219] Ibid. p. 366. [220] "Animals and Plants under Domestication," vol. ii. p. 402. [221] See _Fortnightly Review_, New Series, vol. iii. April 1868, p. 352. [222] This appeared in the _Rivista Contemporanea Nazionale Italiana_, and was translated and given to the English public in _Scientific Opinion_ for September 29, October 6, and October 13, 1869, pp. 365, 391, and 407. [223] See _Scientific Opinion_, of October 13, 1869, p. 407. [224] See _Scientific Opinion_ of September 29, 1869, p. 366. [225] _Fortnightly Review_, New Series, vol. iii. April 1868, p. 508. [226] _Scientific Opinion_, of October 13, 1869, p. 408. [227] _Fortnightly Review_, New Series, vol. iii. April 1868, p. 509. [228] "Histoire Naturelle, générale et particulière," tome ii. 1749, p. 327. "Ces liqueurs séminales sont toutes deux un extrait de toutes les parties du corps," &c. [229] See _Nature_, March 3, 1870, p. 454. Mr. Wallace says (referring to Mr. Croll's paper in the _Phil. Mag._), "As we are now, and have been for 60,000 years, in a period of low eccentricity, _the rate of change of species during that time may be no measure of the rate that has generally obtained in past geological epochs_." [230] "Habit and Intelligence," vol. i. p. 344. [231] If anyone were to contend that beside the opium there existed a real distinct objective entity, "its soporific virtue," he would be open to ridicule indeed. But the constitution of our minds is such that we cannot but distinguish ideally a thing from its even essential attributes and qualities. The joke is sufficiently amusing, however, regarded as the solemn enunciation of a mere truism. [232] Noticed by Professor Owen in his "Archetype," p. 76. Recently it has been attempted to discredit Darwinism in France by speaking of it as "_de la science mousseuse!_" [233] "Lay Sermons," p. 342. [234] Introductory Lecture of February 14, 1870, pp. 24-30, Figs. 1-4. (Churchill and Sons.) [235] See especially "Animals and Plants under Domestication," vol. ii. chap. xviii. [236] "Origin of Species," 5th edition, pp. 323, 324. [237] "Animals and Plants under Domestication," vol. ii. p. 2. [238] Ibid. p. 25. [239] Ibid. p. 151. [240] Ibid. p. 157. [241] Ibid. p. 158. [242] "Animals and Plants under Domestication," vol. i. p. 291. [243] Though hardly necessary, it may be well to remark that the views here advocated in no way depend upon the truth of the doctrine of Spontaneous Generation. [244] Vol. iii. p. 808. [245] This is hardly an exact representation of Mr. Darwin's view. On his theory, if a favourable variation happens to arise (the external circumstances remaining the same), it will yet be preserved. [246] See 2nd edition, p. 113. [247] "Essays, Philosophical and Theological," Trübner and Co., First Series, 1866, p. 190. "Every relative disability may be read two ways. A disqualification in the nature of thought for knowing _x_ is, from the other side, a disqualification in the nature of _x_ from being known. To say then that the First Cause is wholly removed from our apprehension is not simply a disclaimer of faculty on our part: it is a charge of inability against the First Cause too. The dictum about it is this: 'It is a Being that may exist out of knowledge, but that is precluded from entering within the sphere of knowledge.' We are told in one breath that this Being must be in every sense 'perfect, complete, total--including in itself all power, and transcending all law' (p. 38); and in another that this perfect and omnipotent One is totally incapable of revealing any one of an infinite store of attributes. Need we point out the contradictions which this position involves? If you abide by it, you deny the Absolute and Infinite in the very act of affirming it, for, in debarring the First Cause from self-revelation, you impose a limit on its nature. And in the very act of declaring the First Cause incognizable, you do not permit it to remain unknown. For that only is unknown, of which you can neither affirm nor deny any predicate; here you deny the power of self-disclosure to the 'Absolute,' of which therefore something is known;--viz., that nothing can be known!" [248] Loc. cit. p. 108. [249] Loc. cit. p. 43. [250] Loc. cit. p. 46. [251] Mr. J. Martineau, in his "Essays," vol. i. p. 211, observes, "Mr. Spencer's conditions of pious worship are hard to satisfy; there must be between the Divine and human no communion of thought, relations of conscience, or approach of affection." ... "But you cannot constitute a religion out of mystery alone, any more than out of knowledge alone; nor can you measure the relation of doctrines to humility and piety by the mere amount of conscious darkness which they leave. All worship, being directed to what is _above_ us and transcends our comprehension, stands in presence of a mystery. But not all that stands before a mystery is worship." [252] "Lay Sermons," p. 20. [253] Loc. cit. p. 109. [254] Loc. cit. p. 111. [255] In this criticism on Mr. Herbert Spencer, the Author finds he has been anticipated by Mr. James Martineau. (See "Essays," vol. i. p. 208.) [256] Loc. cit. p. 29. [257] The Author means by this, that it is _directly_ and _immediately_ the act of God, the word "supernatural" being used in a sense convenient for the purposes of this work, and not in its ordinary theological sense. [258] The phrase "order of nature" is not here used in its theological sense as distinguished from the "order of grace," but as a term, here convenient, to denote actions not due to direct and immediate Divine intervention. [259] "A Free Examination of Darwin's Treatise," p. 29, reprinted from the _Atlantic Monthly_ for July, August, and October, 1860. [260] "Origin of Species," 5th edition, p. 571. [261] "Animals and Plants under Domestication," vol. ii. p. 431. [262] The Rev. Baden Powell says, "All sciences approach perfection as they approach to a unity of first principles,--in all cases recurring to or tending towards certain high elementary conceptions which are the representatives of the unity of the great archetypal ideas according to which the whole system is arranged. Inductive conceptions, very partially and imperfectly realized and apprehended by human intellect, are the exponents in our minds of these great principles in nature." "All science is but the partial reflexion in the _reason of man_, of the great all-pervading _reason of the universe_. And thus the _unity_ of science is the reflexion of the _unity_ of nature, and of the _unity_ of that supreme reason and intelligence which pervades and rules over nature, and from whence all reason and all science is derived." (Unity of Worlds, Essay i., § ii.; Unity of Sciences, pp. 79 and 81.) Also he quotes from Oersted's "Soul in Nature" (pp. 12, 16, 18, 87, 92, and 377). "If the laws of reason did not exist in nature, we should vainly attempt to force them upon her: if the laws of nature did not exist in our reason, we should not be able to comprehend them." ... "We find an agreement between our reason and works which our reason did not produce." ... "All existence is a dominion of reason." "The laws of nature are laws of reason, and altogether form an endless unity of reason; ... one and the same throughout the universe." [263] In the same way Mr. Lewes, in criticising the Duke of Argyll's "Reign of Law" (_Fortnightly Review_, July 1867, p. 100), asks whether we should consider that man wise who spilt a gallon of wine in order to fill a wineglass? But, because we should not do so, it by no means follows that we can argue from such an action to the action of God in the visible universe. For the man's object, in the case supposed, is simply to fill the wine-glass, and the wine spilt is so much loss. With God it may be entirely different in both respects. All these objections are fully met by the principle thus laid down by St. Thomas Aquinas: "Quod si aliqua causa particularis deficiat a suo effectu, hoc est propter aliquam causam particularem impediantem quæ continetur sub ordine causæ universalis. Unde effectus ordinem causæ universalis nullo modo potest exire." ... "Sicut indigestio contingit præter ordinem virtutis nutritivæ ex aliquo impedimento, puta ex grossitie cibi, quam necesse est reducere in aliam causam, et sic usque ad causam primam universalem. Cum igitur Deus sit prima causa universalis non unius generi tantum, sed universaliter totius entis, impossibile est quod aliquid contingat præter ordinem divinæ gubernationis; sed ex hoc ipso quod aliquid ex unâ parte videtur exire ab ordine divinæ providentiæ, quo consideratur secundam aliquam particularem causam, necesse est quod in eundem ordinem relabatur secundum aliam causam."--_Sum. Theol_. p. i. q. 19, a. 6, and q. 103, a. 7. [264] "Unity of Worlds," Essay ii., § ii., p. 260. [265] See the exceedingly good passage on this subject by the Rev. Dr. Newman, in his "Discourses for Mixed Congregations," 1850, p. 345. [266] See Mr. G. H. Lewes's "Sea-Side Studies," for some excellent remarks, beginning at p. 329, as to the small susceptibility of certain animals to pain. [267] "Philosophy of Creation," Essay iii., § iv., p. 480. [268] It seems almost strange that modern English thought should so long hold aloof from familiar communion with Christian writers of other ages and countries. It is rarely indeed that acquaintance is shown with such authors, though a bright example to the contrary was set by Sir William Hamilton. Sir Charles Lyell (in his "Principles of Geology," 7th edition, p. 35) speaks with approval of the early Italian geologists. Of Vallisneri he says, "I return with pleasure to the geologists of Italy who preceded, as has been already shown, the naturalists of other countries in their investigations into the ancient history of the earth, and who still maintained a decided pre-eminence. They refuted and ridiculed the physico-theological systems of Burnet, Whiston, and Woodward; while Vallisneri, in his comments on the Woodwardian theory, remarked how much the interests of religion, as well as of those of sound philosophy, had suffered by perpetually mixing up the sacred writings with questions of physical science." Again, he quotes the Carmelite friar Generelli, who, illustrating Moro before the Academy of Cremona in 1749, strongly opposed those who would introduce the supernatural into the domain of nature. "I hold in utter abomination, most learned Academicians! those systems which are built with their foundations in the air, and cannot be propped up without a miracle, and I undertake, with the assistance of Moro, to explain to you how these marine monsters were transported into the mountains by natural causes." Sir Charles Lyell notices with exemplary impartiality the spirit of intolerance on both sides. How in France, Buffon, on the one hand, was influenced by the theological faculty of the Sorbonne to recant his theory of the earth, and how Voltaire, on the other, allowed his prejudices to get the better, if not of his judgment, certainly of his expression of it. Thinking that fossil remains of shells, &c., were evidence in favour of orthodox views, Voltaire, Sir Charles Lyell (Principles, p. 56) tells us, "endeavoured to inculcate scepticism as to the real nature of such shells, and to recall from contempt the exploded dogma of the sixteenth century, that they were sports of nature. He also pretended that vegetable impressions were not those of real plants." ... "He would sometimes, in defiance of all consistency, shift his ground when addressing the vulgar; and, admitting the true nature of the shells collected in the Alps and other places, pretend that they were Eastern species, which had fallen from the hats of pilgrims coming from Syria. The numerous essays written by him on geological subjects were all calculated to strengthen prejudices, partly because he was ignorant of the real state of the science, and partly from his bad faith." As to the harmony between many early Church writers of great authority and modern views as regards certain matters of geology, see "Geology and Revelation," by the Rev. Gerald Molloy, D.D., London, 1870. [269] "De Genesi ad Litt.," lib. v., cap. v., No. 14 in Ben. Edition, voi. iii. p. 186. [270] Lib. cit., cap. xxii., No. 44. [271] Lib. cit., "De Trinitate," lib. iii., cap. viii, No. 14. [272] Lib. cit., cap. ix., No. 16. [273] St. Thomas, Summa, i., quest. 67, art. 4, ad 3. [274] Primæ Partis, vol. ii., quest. 74, art. 2. [275] Lib. cit., quest. 71, art. 1. [276] Lib. cit., quest. 45, art. 8. [277] _Vide_ In Genesim Comment, cap. i. [278] Roger Bacon, Opus tertium, c. ix. p. 27, quoted in the _Rambler_ for 1859, vol. xii. p. 375. [279] See _Nature_, June and July, 1870. Those who, like Professors Huxley and Tyndall, do not accept his conclusions, none the less agree with him in principle, though they limit the evolution of the organic world from the inorganic to a very remote period of the world's history. (See Professor Huxley's address to the British Association at Liverpool, 1870, p. 17.) [280] "Lectures on Metaphysics and Logic," vol. i. Lecture ii., p. 40. [281] In the same way that an undue cultivation of any one kind of knowledge is prejudicial to philosophy. Mr. James Martineau well observes, "Nothing is more common than to see maxims, which are unexceptionable as the assumptions of particular sciences, coerced into the service of a universal philosophy, and so turned into instruments of mischief and distortion. That "we can know nothing but phenomena,"--that "causation is simply constant priority,"--that "men are governed invariably by their interests," are examples of rules allowable as dominant hypotheses in physics or political economy, but exercising a desolating tyranny when thrust on to the throne of universal empire. He who seizes upon these and similar maxims, and carries them in triumph on his banner, may boast of his escape from the uncertainties of metaphysics, but is himself all the while the unconscious victim of their very vulgarest deception." ("Essays," Second Series, _A Plea for Philosophical Studies_, p. 421.) [282] Lecky's "History of Rationalism," vol. i. p. 73. [283] "Lectures on University Subjects," by J. H. Newman, D.D., p. 322. [284] Loc. cit. p. 324. [285] Thus Professor Tyndall, in the _Pall Mall Gazette_ of June 15, 1868, speaking of physical science, observes, "The _logical feebleness_ of science is not sufficiently borne in mind. It keeps down the weed of superstition, not by logic, but by slowly rendering the mental soil unfit for its cultivation." [286] By this it is not, of course, meant to deny that the existence of God can be demonstrated so as to demand the assent of the intellect taken, so to speak, by itself. [287] See some excellent remarks in the Rev. Dr. Newman's Parochial Sermons--the new edition (1869), vol. i. p. 211. [288] _American Journal of Science_, July 1860, p. 143, quoted in Dr. Asa Gray's pamphlet, p. 47. [289] See _The Academy_ for October 1869, No. 1, p. 13. [290] Professor Huxley goes on to say that the mechanist may, in turn, demand of the teleologist how the latter knows it was so intended. To this it may be replied he knows it as a necessary truth of reason deduced from his own primary intuitions, which intuitions cannot be questioned without _absolute_ scepticism. [291] The Professor doubtless means the _direct_ and _immediate_ result. (See Trans. Zool. Soc. vol. v. p. 90.) [292] "Natural Selection," p. 280. [293] Dr. Asa Gray, _e.g._, has thus understood Mr. Darwin. The Doctor says in his pamphlet, p. 38, "Mr. Darwin uses expressions which imply that the natural forms which surround us, because they have a history or natural sequence, could have been only generally, but not particularly designed,--a view at once superficial and contradictory; whereas his true line should be, that his hypothesis concerns the _order_ and not the _cause_, the _how_ and not the _why_ of the phenomena, and so leaves the question of design just where it was before." [294] "All science is but the partial reflexion in the _reason of man_, of the great all-pervading _reason of the universe_. And the _unity_ of science is the reflexion of the _unity_ of nature and of the _unity_ of that supreme reason and intelligence which pervades and rules over nature, and from whence all reason and all science is derived." (Rev. Baden Powell, "Unity of the Sciences," Essay i. § ii. p. 81.) [295] "The Reign of Law," p. 40. [296] Though Mr. Darwin's epithets denoting design are metaphorical, his admiration of the result is unequivocal, nay, enthusiastic! [297] See "Habit and Intelligence," vol. i. p. 348. [298] The term, as before said, not being used in its ordinary theological sense, but to denote an immediate Divine action as distinguished from God's action through the powers conferred on the physical universe. [299] See "Natural Selection," pp. 332 to 360. [300] Loc. cit., p. 349. [301] See Professor Huxley's "Lessons in Elementary Physiology," p. 218. [302] It may be objected, perhaps, that excessive delicacy of the ear might have been produced by having to guard against the approach of enemies, some savages being remarkable for their keenness of hearing at great distances. But the perceptions of _intensity_ and _quality_ of sound are very different. Some persons who have an extremely acute ear for delicate sounds, and who are fond of music, have yet an incapacity for detecting whether an instrument is slightly out of tune. [303] Loc. cit., pp. 351, 352. [304] Loc. cit., p. 368. [305] Loc. cit., p. 350. [306] Published by John Churchill. [307] Natural Selection, p. 324. [308] The italics are not Mr. Wallace's. [309] "Unity of Worlds," Essay ii. § ii. p. 247. [310] Ibid. Essay i. § ii. p. 76. [311] Ibid. Essay iii. § iv. p. 466. [312] A good exposition of how an inferior action has to yield to one higher is given by Dr. Newman in his "Lectures on University Subjects," p. 372. "What is true in one science, is dictated to us indeed according to that science, but not according to another science, or in another department. "What is certain in the military art, has force in the military art, but not in statesmanship; and if statesmanship be a higher department of action than war, and enjoins the contrary, it has no force on our reception and obedience at all. And so what is true in medical science, might in all cases be carried out, _were_ man a mere animal or brute without a soul; but since he is a rational, responsible being, a thing may be ever so true in medicine, yet may be unlawful in fact, in consequence of the _higher_ law of morals and religion coming to some different conclusion." [313] Quoted from the _Rambler_ of March 1860, p. 364: [Greek: "Hopou men oun hapanta sunebê, hôsper kain ei heneka tou egineto, tauta men esôthê apo tou automatou sustanta epitêdeiôs hosa de mê houtôs apôleto kai apollutai, kathapeo Empedoklês legei ta bougenê kai androprôra.]"--ARIST. _Phys._ ii. c. 8. 
22728	----	generously made available by The Internet Archive/Canadian Libraries) THE FOUNDATIONS OF THE ORIGIN OF SPECIES CAMBRIDGE UNIVERSITY PRESS London: FETTER LANE, E.C. C. F. CLAY, MANAGER {Illustration} Edinburgh: 100, PRINCES STREET ALSO London: H. K. LEWIS, 136, GOWER STREET, W.C. Berlin: A. ASHER AND CO. Leipzig: F. A. BROCKHAUS New York: G. P. PUTNAM'S SONS Bombay and Calcutta: MACMILLAN AND Co., LTD. _All rights reserved_ {Illustration: Charles Darwin from a photograph by Maull & Fox in 1854} THE FOUNDATIONS OF THE ORIGIN OF SPECIES TWO ESSAYS WRITTEN IN 1842 AND 1844 by CHARLES DARWIN Edited by his son FRANCIS DARWIN Honorary Fellow of Christ's College Cambridge: at the University Press 1909 Astronomers might formerly have said that God ordered each planet to move in its particular destiny. In same manner God orders each animal created with certain form in certain country. But how much more simple and sublime power,--let attraction act according to certain law, such are inevitable consequences,--let animal(s) be created, then by the fixed laws of generation, such will be their successors. From DARWIN'S _Note Book_, 1837, p. 101. TO THE MASTER AND FELLOWS OF CHRIST'S COLLEGE, THIS BOOK IS DEDICATED BY THE EDITOR IN TOKEN OF RESPECT AND GRATITUDE CONTENTS ESSAY OF 1842 PAGES INTRODUCTION xi PART I § i. On variation under domestication, and on the principles of selection 1 § ii. On variation in a state of nature and on the natural means of selection 4 § iii. On variation in instincts and other mental attributes 17 PART II §§ iv. and v. On the evidence from Geology. (The reasons for combining the two sections are given in the Introduction) 22 § vi. Geographical distribution 29 § vii. Affinities and classification 35 § viii. Unity of type in the great classes 38 § ix. Abortive organs 45 § x. Recapitulation and conclusion 48 ESSAY OF 1844 PART I CHAPTER I 57-80 ON THE VARIATION OF ORGANIC BEINGS UNDER DOMESTICATION; AND ON THE PRINCIPLES OF SELECTION. Variation On the hereditary tendency Causes of Variation On Selection Crossing Breeds Whether our domestic races have descended from one or more wild stocks Limits to Variation in degree and kind In what consists Domestication--Summary CHAPTER II 81-111 ON THE VARIATION OF ORGANIC BEINGS IN A WILD STATE; ON THE NATURAL MEANS OF SELECTION; AND ON THE COMPARISON OF DOMESTIC RACES AND TRUE SPECIES. Variation Natural means of Selection Differences between "Races" and "Species":-first, in their trueness or variability Difference between "Races" and "Species" in fertility when crossed Causes of Sterility in Hybrids Infertility from causes distinct from hybridisation Points of Resemblance between "Races" and "Species" External characters of Hybrids and Mongrels Summary Limits of Variation CHAPTER III 112-132 ON THE VARIATION OF INSTINCTS AND OTHER MENTAL ATTRIBUTES UNDER DOMESTICATION AND IN A STATE OF NATURE; ON THE DIFFICULTIES IN THIS SUBJECT; AND ON ANALOGOUS DIFFICULTIES WITH RESPECT TO CORPOREAL STRUCTURES. Variation of mental attributes under domestication Hereditary habits compared with instincts Variation in the mental attributes of wild animals Principles of Selection applicable to instincts Difficulties in the acquirement of complex instincts by Selection Difficulties in the acquirement by Selection of complex corporeal structures PART II ON THE EVIDENCE FAVOURABLE AND OPPOSED TO THE VIEW THAT SPECIES ARE NATURALLY FORMED RACES, DESCENDED FROM COMMON STOCKS. CHAPTER IV 133-143 ON THE NUMBER OF INTERMEDIATE FORMS REQUIRED ON THE THEORY OF COMMON DESCENT; AND ON THEIR ABSENCE IN A FOSSIL STATE CHAPTER V 144-150 GRADUAL APPEARANCE AND DISAPPEARANCE OF SPECIES. Gradual appearance of species Extinction of species CHAPTER VI ON THE GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS IN PAST AND PRESENT TIMES. SECTION FIRST 151-174 Distribution of the inhabitants in the different continents Relation of range in genera and species Distribution of the inhabitants in the same continent Insular Faunas Alpine Floras Cause of the similarity in the floras of some distant mountains Whether the same species has been created more than once On the number of species, and of the classes to which they belong in different regions SECOND SECTION 174-182 Geographical distribution of extinct organisms Changes in geographical distribution Summary on the distribution of living and extinct organic beings SECTION THIRD 183-197 An attempt to explain the foregoing laws of geographical distribution, on the theory of allied species having a common descent Improbability of finding fossil forms intermediate between existing species CHAPTER VII 198-213 ON THE NATURE OF THE AFFINITIES AND CLASSIFICATION OF ORGANIC BEINGS. Gradual appearance and disappearance of groups What is the Natural System? On the kind of relation between distinct groups Classification of Races or Varieties Classification of Races and Species similar Origin of genera and families CHAPTER VIII 214-230 UNITY OF TYPE IN THE GREAT CLASSES; AND MORPHOLOGICAL STRUCTURES. Unity of Type Morphology Embryology Attempt to explain the facts of embryology On the graduated complexity in each great class Modification by selection of the forms of immature animals Importance of embryology in classification Order in time in which the great classes have first appeared CHAPTER IX 231-238 ABORTIVE OR RUDIMENTARY ORGANS. The abortive organs of Naturalists The abortive organs of Physiologists Abortion from gradual disuse CHAPTER X 239-255 RECAPITULATION AND CONCLUSION. Recapitulation Why do we wish to reject the Theory of Common Descent? Conclusion INDEX 257 Portrait _frontispiece_ Facsimile _to face_ p. 50 INTRODUCTION We know from the contents of Charles Darwin's Note Book of 1837 that he was at that time a convinced Evolutionist{1}. Nor can there be any doubt that, when he started on board the _Beagle_, such opinions as he had were on the side of immutability. When therefore did the current of his thoughts begin to set in the direction of Evolution? {1} See the extracts in _Life and Letters of Charles Darwin_, ii. p. 5. We have first to consider the factors that made for such a change. On his departure in 1831, Henslow gave him vol. I. of Lyell's _Principles_, then just published, with the warning that he was not to believe what he read{2}. But believe he did, and it is certain (as Huxley has forcibly pointed out{3}) that the doctrine of uniformitarianism when applied to Biology leads of necessity to Evolution. If the extermination of a species is no more catastrophic than the natural death of an individual, why should the birth of a species be any more miraculous than the birth of an individual? It is quite clear that this thought was vividly present to Darwin when he was writing out his early thoughts in the 1837 Note Book{4}:-- "Propagation explains why modern animals same type as extinct, which is law almost proved. They die, without they change, like golden pippins; it is a _generation of species_ like generation _of individuals_." "If _species_ generate other _species_ their race is not utterly cut off." {2} The second volume,--especially important in regard to Evolution,--reached him in the autumn of 1832, as Prof. Judd has pointed out in his most interesting paper in _Darwin and Modern Science_. Cambridge, 1909. {3} Obituary Notice of C. Darwin, _Proc. R. Soc._ vol. 44. Reprinted in Huxley's _Collected Essays_. See also _Life and Letters of C. Darwin_, ii. p. 179. {4} See the extracts in the _Life and Letters_, ii. p. 5. These quotations show that he was struggling to see in the origin of species a process just as scientifically comprehensible as the birth of individuals. They show, I think, that he recognised the two things not merely as similar but as identical. It is impossible to know how soon the ferment of uniformitarianism began to work, but it is fair to suspect that in 1832 he had already begun to see that mutability was the logical conclusion of Lyell's doctrine, though this was not acknowledged by Lyell himself. There were however other factors of change. In his Autobiography{5} he wrote:--"During the voyage of the _Beagle_ I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos; secondly, by the manner in which closely allied animals replace one another in proceeding southward over the Continent; and thirdly, by the South American character of most of the productions of the Galapagos archipelago, and more especially by the manner in which they differ slightly on each island of the group; none of the islands appearing to be very ancient in a geological sense. It was evident that such facts as these, as well as many others, could only be explained on the supposition that species gradually become modified; and the subject haunted me." {5} _Life and Letters_, i. p. 82. Again we have to ask: how soon did any of these influences produce an effect on Darwin's mind? Different answers have been attempted. Huxley{6} held that these facts could not have produced their essential effect until the voyage had come to an end, and the "relations of the existing with the extinct species and of the species of the different geographical areas with one another were determined with some exactness." He does not therefore allow that any appreciable advance towards evolution was made during the actual voyage of the _Beagle_. {6} _Obituary Notice_, _loc. cit._ Professor Judd{7} takes a very different view. He holds that November 1832 may be given with some confidence as the "date at which Darwin commenced that long series of observations and reasonings which eventually culminated in the preparation of the _Origin of Species_." {7} _Darwin and Modern Science._ Though I think these words suggest a more direct and continuous march than really existed between fossil-collecting in 1832 and writing the _Origin of Species_ in 1859, yet I hold that it was during the voyage that Darwin's mind began to be turned in the direction of Evolution, and I am therefore in essential agreement with Prof. Judd, although I lay more stress than he does on the latter part of the voyage. Let us for a moment confine our attention to the passage, above quoted, from the Autobiography and to what is said in the Introduction to the _Origin_, Ed. i., viz. "When on board H.M.S. 'Beagle,' as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent." These words, occurring where they do, can only mean one thing,--namely that the facts suggested an evolutionary interpretation. And this being so it must be true that his thoughts _began to flow in the direction of Descent_ at this early date. I am inclined to think that the "new light which was rising in his mind{8}" had not yet attained any effective degree of steadiness or brightness. I think so because in his Pocket Book under the date 1837 he wrote, "In July opened first note-book on 'transmutation of species.' Had been greatly struck _from about month of previous March_{9} on character of South American fossils, and species on Galapagos Archipelago. These facts origin (_especially latter_), of all my views." But he did not visit the Galapagos till 1835 and I therefore find it hard to believe that his evolutionary views attained any strength or permanence until at any rate quite late in the voyage. The Galapagos facts are strongly against Huxley's view, for Darwin's attention was "thoroughly aroused{10}" by comparing the birds shot by himself and by others on board. The case must have struck him at once,--without waiting for accurate determinations,--as a microcosm of evolution. {8} Huxley, _Obituary_, p. xi. {9} In this citation the italics are mine. {10} _Journal of Researches_, Ed. 1860, p. 394. It is also to be noted, in regard to the remains of extinct animals, that, in the above quotation from his Pocket Book, he speaks of March 1837 as the time at which he began to be "greatly struck on character of South American fossils," which suggests at least that the impression made in 1832 required reinforcement before a really powerful effect was produced. We may therefore conclude, I think, that the evolutionary current in my father's thoughts had continued to increase in force from 1832 onwards, being especially reinforced at the Galapagos in 1835 and again in 1837 when he was overhauling the results, mental and material, of his travels. And that when the above record in the Pocket Book was made he unconsciously minimised the earlier beginnings of his theorisings, and laid more stress on the recent thoughts which were naturally more vivid to him. In his letter{11} to Otto Zacharias (1877) he wrote, "On my return home in the autumn of 1836, I immediately began to prepare my Journal for publication, and then saw how many facts indicated the common descent of species." This again is evidence in favour of the view that the later growths of his theory were the essentially important parts of its development. {11} F. Darwin's _Life of Charles Darwin_ (in one volume), 1892, p. 166. In the same letter to Zacharias he says, "When I was on board the _Beagle_ I believed in the permanence of species, but as far as I can remember vague doubts occasionally flitted across my mind." Unless Prof. Judd and I are altogether wrong in believing that late or early in the voyage (it matters little which) a definite approach was made to the evolutionary standpoint, we must suppose that in 40 years such advance had shrunk in his recollection to the dimensions of "vague doubts." The letter to Zacharias shows I think some forgetting of the past where the author says, "But I did not become convinced that species were mutable until, I think, two or three years had elapsed." It is impossible to reconcile this with the contents of the evolutionary Note Book of 1837. I have no doubt that in his retrospect he felt that he had not been "convinced that species were mutable" until he had gained a clear conception of the mechanism of natural selection, _i.e._ in 1838-9. But even on this last date there is some room, not for doubt, but for surprise. The passage in the Autobiography{12} is quite clear, namely that in October 1838 he read Malthus's _Essay on the principle of Population_ and "being well prepared to appreciate the struggle for existence ..., it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here then I had at last got a theory by which to work." {12} _Life and Letters_, i. p. 83. It is surprising that Malthus should have been needed to give him the clue, when in the Note Book of 1837 there should occur--however obscurely expressed--the following forecast{13} of the importance of the survival of the fittest. "With respect to extinction, we can easily see that a variety of the ostrich (Petise{14}), may not be well adapted, and thus perish out; or on the other hand, like Orpheus{15}, being favourable, many might be produced. This requires the principle that the permanent variations produced by confined breeding and changing circumstances are continued and produce<d> according to the adaptation of such circumstances, and therefore that death of species is a consequence (contrary to what would appear in America) of non-adaptation of circumstances." {13} _Life and Letters_, ii. p. 8. {14} Avestruz Petise, _i.e. Rhea Darwini_. {15} A bird. I can hardly doubt, that with his knowledge of the interdependence of organisms and the tyranny of conditions, his experience would have crystallized out into "a theory by which to work" even without the aid of Malthus. In my father's Autobiography{16} he writes, "In June 1842 I first allowed myself the satisfaction of writing a very brief abstract of my theory in pencil in 35 pages; and this was enlarged during the summer of 1844 into one of 230 pages{17}, which I had fairly copied out and still possess." These two Essays, of 1842 and 1844, are now printed under the title _The Foundations of the Origin of Species_. {16} _Life and Letters_, i. p. 84. {17} It contains as a fact 231 pp. It is a strongly bound folio, interleaved with blank pages, as though for notes and additions. His own MS. from which it was copied contains 189 pp. It will be noted that in the above passage he does not mention the MS. of 1842 as being in existence, and when I was at work on _Life and Letters_ I had not seen it. It only came to light after my mother's death in 1896 when the house at Down was vacated. The MS. was hidden in a cupboard under the stairs which was not used for papers of any value, but rather as an overflow for matter which he did not wish to destroy. The statement in the Autobiography that the MS. was written in 1842 agrees with an entry in my fathers Diary:-- "1842. May 18th went to Maer. June 15th to Shrewsbury, and on 18th to Capel Curig.... During my stay at Maer and Shrewsbury (five years after commencement) wrote pencil sketch of my species theory." Again in a letter to Lyell (June 18, 1858) he speaks of his "MS. sketch written out in 1842{18}." In the _Origin of Species_, Ed. i. p. 1, he speaks of beginning his speculations in 1837 and of allowing himself to draw up some "short notes" after "five years' work," _i.e._ in 1842. So far there seems no doubt as to 1842 being the date of the first sketch; but there is evidence in favour of an earlier date{19}. Thus across the Table of Contents of the bound copy of the 1844 MS. is written in my father's hand "This was sketched in 1839." Again in a letter to Mr Wallace{20} (Jan. 25, 1859) he speaks of his own contributions to the Linnean paper{21} of July 1, 1858, as "written in 1839, now just twenty years ago." This statement as it stands is undoubtedly incorrect, since the extracts are from the MS. of 1844, about the date of which no doubt exists; but even if it could be supposed to refer to the 1842 Essay, it must, I think, be rejected. I can only account for his mistake by the supposition that my father had in mind the date (1839) at which the framework of his theory was laid down. It is worth noting that in his Autobiography (p. 88) he speaks of the time "about 1839, when the theory was clearly conceived." However this may be there can be no doubt that 1842 is the correct date. Since the publication of _Life and Letters_ I have gained fresh evidence on this head. A small packet containing 13 pp. of MS. came to light in 1896. On the outside is written "First Pencil Sketch of Species Theory. Written at Maer and Shrewsbury during May and June 1842." It is not however written in pencil, and it consists of a single chapter on _The Principles of Variation in Domestic Organisms_. A single unnumbered page is written in pencil, and is headed "Maer, May 1842, useless"; it also bears the words "This page was thought of as introduction." It consists of the briefest sketch of the geological evidence for evolution, together with words intended as headings for discussion,--such as "Affinity,--unity of type,--foetal state,--abortive organs." {18} _Life and Letters_, ii. p. 116. {19} _Life and Letters_, ii. p. 10. {20} _Life and Letters_, ii. p. 146. {21} _J. Linn. Soc. Zool._ iii. p. 45. The back of this "useless" page is of some interest, although it does not bear on the question of date,--the matter immediately before us. It seems to be an outline of the Essay or sketch of 1842, consisting of the titles of the three chapters of which it was to have consisted. "I. The Principles of Var. in domestic organisms. "II. The possible and probable application of these same principles to wild animals and consequently the possible and probable production of wild races, analogous to the domestic ones of plants and animals. "III. The reasons for and against believing that such races have really been produced, forming what are called species." It will be seen that Chapter III as originally designed corresponds to Part II (p. 22) of the Essay of 1842, which is (p. 7) defined by the author as discussing "whether the characters and relations of animated things are such as favour the idea of wild species being races descended from a common stock." Again at p. 23 the author asks "What then is the evidence in favour of it (the theory of descent) and what the evidence against it." The generalised section of his Essay having been originally Chapter III{22} accounts for the curious error which occurs in pp. 18 and 22 where the second Part of the Essay is called Part III. {22} It is evident that _Parts_ and _Chapters_ were to some extent interchangeable in the author's mind, for p. 1 (of the MS. we have been discussing) is headed in ink Chapter I, and afterwards altered in pencil to Part I. The division of the Essay into two parts is maintained in the enlarged Essay of 1844, in which he writes: "The Second Part of this work is devoted to the general consideration of how far the general economy of nature justifies or opposes the belief that related species and genera are descended from common stocks." The _Origin of Species_ however is not so divided. We may now return to the question of the date of the Essay. I have found additional evidence in favour of 1842 in a sentence written on the back of the Table of Contents of the 1844 MS.--not the copied version but the original in my father's writing: "This was written and enlarged from a sketch in 37 pages{23} in Pencil (the latter written in summer of 1842 at Maer and Shrewsbury) in beginning of 1844, and finished it <_sic_> in July; and finally corrected the copy by Mr Fletcher in the last week in September." On the whole it is impossible to doubt that 1842 is the date of the earlier of the two Essays. {23} On p. 23 of the MS. of the _Foundations_ is a reference to the "back of p. 21 bis": this suggests that additional pages had been interpolated in the MS. and that it may once have had 37 in place of 35 pp. The sketch of 1842 is written on bad paper with a soft pencil, and is in many parts extremely difficult to read, many of the words ending in mere scrawls and being illegible without context. It is evidently written rapidly, and is in his most elliptical style, the articles being frequently omitted, and the sentences being loosely composed and often illogical in structure. There is much erasure and correction, apparently made at the moment of writing, and the MS. does not give the impression of having been re-read with any care. The whole is more like hasty memoranda of what was clear to himself, than material for the convincing of others. Many of the pages are covered with writing on the back, an instance of his parsimony in the matter of paper{24}. This matter consists partly of passages marked for insertion in the text, and these can generally (though by no means always) be placed where he intended. But he also used the back of one page for a preliminary sketch to be rewritten on a clean sheet. These parts of the work have been printed as footnotes, so as to allow what was written on the front of the pages to form a continuous text. A certain amount of repetition is unavoidable, but much of what is written on the backs of the pages is of too much interest to be omitted. Some of the matter here given in footnotes may, moreover, have been intended as the final text and not as the preliminary sketch. {24} _Life and Letters_, i. p. 153. When a word cannot be deciphered, it is replaced by:--<illegible>, the angular brackets being, as already explained, a symbol for an insertion by the editor. More commonly, however, the context makes the interpretation of a word reasonably sure although the word is not strictly legible. Such words are followed by an inserted mark of interrogation <?>. Lastly, words inserted by the editor, of which the appropriateness is doubtful, are printed thus <variation?>. Two kinds of erasure occur in the MS. of 1842. One by vertical lines which seem to have been made when the 35 pp. MS. was being expanded into that of 1844, and merely imply that such a page is done with: and secondly the ordinary erasures by horizontal lines. I have not been quite consistent in regard to these: I began with the intention of printing (in square brackets) all such erasures. But I ultimately found that the confusion introduced into the already obscure sentences was greater than any possible gain; and many such erasures are altogether omitted. In the same way I have occasionally omitted hopelessly obscure and incomprehensible fragments, which if printed would only have burthened the text with a string of <illegible>s and queried words. Nor have I printed the whole of what is written on the backs of the pages, where it seemed to me that nothing but unnecessary repetition would have been the result. In the matter of punctuation I have given myself a free hand. I may no doubt have misinterpreted the author's meaning in so doing, but without such punctuation, the number of repellantly crabbed sentences would have been even greater than at present. In dealing with the Essay of 1844, I have corrected some obvious slips without indicating such alterations, because the MS. being legible, there is no danger of changing the author's meaning. The sections into which the Essay of 1842 is divided are in the original merely indicated by a gap in the MS. or by a line drawn across the page. No titles are given except in the case of § VIII.; and § II. is the only section which has a number in the original. I might equally well have made sections of what are now subsections, _e.g. Natural Selection_ p. 7, or _Extermination_ p. 28. But since the present sketch is the germ of the Essay of 1844, it seemed best to preserve the identity between the two works, by using such of the author's divisions as correspond to the chapters of the enlarged version of 1844. The geological discussion with which Part II begins corresponds to two chapters (IV and V) of the 1844 Essay. I have therefore described it as §§ IV. and V., although I cannot make sure of its having originally consisted of two sections. With this exception the ten sections of the Essay of 1842 correspond to the ten chapters of that of 1844. The _Origin of Species_ differs from the sketch of 1842 in not being divided into two parts. But the two volumes resemble each other in general structure. Both begin with a statement of what may be called the mechanism of evolution,--variation and selection: in both the argument proceeds from the study of domestic organisms to that of animals and plants in a state of nature. This is followed in both by a discussion of the _Difficulties on Theory_ and this by a section _Instinct_ which in both cases is treated as a special case of difficulty. If I had to divide the _Origin_ (first edition) into two parts without any knowledge of earlier MS., I should, I think, make Part II begin with Ch. VI, _Difficulties on Theory_. A possible reason why this part of the argument is given in Part I of the Essay of 1842 may be found in the Essay of 1844, where it is clear that the chapter on instinct is placed in Part I because the author thought it of importance to show that heredity and variation occur in mental attributes. The whole question is perhaps an instance of the sort of difficulty which made the author give up the division of his argument into two Parts when he wrote the _Origin_. As matters stand §§ IV. and V. of the 1842 Essay correspond to the geological chapters, IX and X, in the _Origin_. From this point onwards the material is grouped in the same order in both works: geographical distribution; affinities and classification; unity of type and morphology; abortive or rudimentary organs; recapitulation and conclusion. In enlarging the Essay of 1842 into that of 1844, the author retained the sections of the sketch as chapters in the completer presentment. It follows that what has been said of the relation of the earlier Essay to the _Origin_ is generally true of the 1844 Essay. In the latter, however, the geological discussion is, clearly instead of obscurely, divided into two chapters, which correspond roughly with Chapters IX and X of the _Origin_. But part of the contents of Chapter X (_Origin_) occurs in Chapter VI (1844) on Geographical Distribution. The treatment of distribution is particularly full and interesting in the 1844 Essay, but the arrangement of the material, especially the introduction of § III. p. 183, leads to some repetition which is avoided in the _Origin_. It should be noted that Hybridism, which has a separate chapter (VIII) in the _Origin_, is treated in Chapter II of the Essay. Finally that Chapter XIII (_Origin_) corresponds to Chapters VII, VIII and IX of the work of 1844. The fact that in 1842, seventeen years before the publication of the _Origin_, my father should have been able to write out so full an outline of his future work, is very remarkable. In his Autobiography{25} he writes of the 1844 Essay, "But at that time I overlooked one problem of great importance.... This problem is the tendency in organic beings descended from the same stock to diverge in character as they become modified." The absence of the principle of divergence is of course also a characteristic of the sketch of 1842. But at p. 37, the author is not far from this point of view. The passage referred to is: "If any species, _A_, in changing gets an advantage and that advantage ... is inherited, _A_ will be the progenitor of several genera or even families in the hard struggle of nature. _A_ will go on beating out other forms, it might come that _A_ would people <the> earth,--we may now not have one descendant on our globe of the one or several original creations{26}." But if the descendants of _A_ have peopled the earth by beating out other forms, they must have diverged in occupying the innumerable diverse modes of life from which they expelled their predecessors. What I wrote{27} on this subject in 1887 is I think true: "Descent with modification implies divergence, and we become so habituated to a belief in descent, and therefore in divergence, that we do not notice the absence of proof that divergence is in itself an advantage." {25} _Life and Letters_, i. p. 84. {26} In the footnotes to the Essay of 1844 attention is called to similar passages. {27} _Life and Letters_, ii. p. 15. The fact that there is no set discussion on the principle of divergence in the 1844 Essay, makes it clear why the joint paper read before the Linnean Society on July 1, 1858, included a letter{28} to Asa Gray, as well as an extract{29} from the Essay of 1844. It is clearly because the letter to Gray includes a discussion on divergence, and was thus, probably, the only document, including this subject, which could be appropriately made use of. It shows once more how great was the importance attached by its author to the principle of divergence. {28} The passage is given in the _Life and Letters_, ii. p. 124. {29} The extract consists of the section on _Natural Means of Selection_, p. 87. I have spoken of the hurried and condensed manner in which the sketch of 1842 is written; the style of the later Essay (1844) is more finished. It has, however, the air of an uncorrected MS. rather than of a book which has gone through the ordeal of proof sheets. It has not all the force and conciseness of the _Origin_, but it has a certain freshness which gives it a character of its own. It must be remembered that the _Origin_ was an abstract or condensation of a much bigger book, whereas the Essay of 1844 was an expansion of the sketch of 1842. It is not therefore surprising that in the _Origin_ there is occasionally evident a chafing against the author's self-imposed limitation. Whereas in the 1844 Essay there is an air of freedom, as if the author were letting himself go, rather than applying the curb. This quality of freshness and the fact that some questions were more fully discussed in 1844 than in 1859, makes the earlier work good reading even to those who are familiar with the _Origin_. The writing of this Essay "during the summer of 1844," as stated in the Autobiography{30}, and "from memory," as Darwin says elsewhere{31}, was a remarkable achievement, and possibly renders more conceivable the still greater feat of the writing of the _Origin_ between July 1858 and September 1859. {30} _Life and Letters_, i. p. 84. {31} _Life and Letters_, ii. p. 18. It is an interesting subject for speculation: what influence on the world the Essay of 1844 would have exercised, had it been published in place of the Origin. The author evidently thought of its publication in its present state as an undesirable expedient, as appears clearly from the following extracts from the _Life and Letters_, vol. ii. pp. 16--18: _C. Darwin to Mrs Darwin._ DOWN, _July 5, 1844_. "... I have just finished my sketch of my species theory. If, as I believe, my theory in time be accepted even by one competent judge, it will be a considerable step in science. "I therefore write this in case of my sudden death, as my most solemn and last request, which I am sure you will consider the same as if legally entered in my will, that you will devote £400 to its publication, and further will yourself, or through Hensleigh{32}, take trouble in promoting it. I wish that my sketch be given to some competent person, with this sum to induce him to take trouble in its improvement and enlargement. I give to him all my books on Natural History, which are either scored or have references at the end to the pages, begging him carefully to look over and consider such passages as actually bearing, or by possibility bearing, on this subject. I wish you to make a list of all such books as some temptation to an editor. I also request that you will hand over <to> him all those scraps roughly divided into eight or ten brown paper portfolios. The scraps, with copied quotations from various works, are those which may aid my editor. I also request that you, or some amanuensis, will aid in deciphering any of the scraps which the editor may think possibly of use. I leave to the editor's judgment whether to interpolate these facts in the text, or as notes, or under appendices. As the looking over the references and scraps will be a long labour, and as the _correcting_ and enlarging and altering my sketch will also take considerable time, I leave this sum of £400 as some remuneration, and any profits from the work. I consider that for this the editor is bound to get the sketch published either at a publisher's or his own risk. Many of the scraps in the portfolios contain mere rude suggestions and early views, now useless, and many of the facts will probably turn out as having no bearing on my theory. {32} Mrs Darwin's brother. "With respect to editors, Mr Lyell would be the best if he would undertake it; I believe he would find the work pleasant, and he would learn some facts new to him. As the editor must be a geologist as well as a naturalist, the next best editor would be Professor Forbes of London. The next best (and quite best in many respects) would be Professor Henslow. Dr Hooker would be _very_ good. The next, Mr Strickland{33}. If none of these would undertake it, I would request you to consult with Mr Lyell, or some other capable man, for some editor, a geologist and naturalist. Should one other hundred pounds make the difference of procuring a good editor, I request earnestly that you will raise £500. {33} After Mr Strickland's name comes the following sentence, which has been erased, but remains legible. "Professor Owen would be very good; but I presume he would not undertake such a work." "My remaining collections in Natural History may be given to any one or any museum where <they> would be accepted...." <The following note seems to have formed part of the original letter, but may have been of later date:> "Lyell, especially with the aid of Hooker (and of any good zoological aid), would be best of all. Without an editor will pledge himself to give up time to it, it would be of no use paying such a sum. "If there should be any difficulty in getting an editor who would go thoroughly into the subject, and think of the bearing of the passages marked in the books and copied out of scraps of paper, then let my sketch be published as it is, stating that it was done several years ago{34}, and from memory without consulting any works, and with no intention of publication in its present form." {34} The words "several years ago, and" seem to have been added at a later date. The idea that the sketch of 1844 might remain, in the event of his death, as the only record of his work, seems to have been long in his mind, for in August, 1854, when he had finished with the Cirripedes, and was thinking of beginning his "species work," he added on the back of the above letter, "Hooker by far best man to edit my species volume. August 1854." I have called attention in footnotes to many points in which the _Origin_ agrees with the _Foundations_. One of the most interesting is the final sentence, practically the same in the Essays of 1842 and 1844, and almost identical with the concluding words of the _Origin_. I have elsewhere pointed out{35} that the ancestry of this eloquent passage may be traced one stage further back,--to the Note Book of 1837. I have given this sentence as an appropriate motto for the _Foundations_ in its character of a study of general laws. It will be remembered that a corresponding motto from Whewell's _Bridgewater Treatise_ is printed opposite the title-page of the _Origin of Species_. {35} _Life and Letters_, ii. p. 9. Mr Huxley who, about the year 1887, read the Essay of 1844, remarked that "much more weight is attached to the influence of external conditions in producing variation and to the inheritance of acquired habits than in the _Origin_." In the _Foundations_ the effect of conditions is frequently mentioned, and Darwin seems to have had constantly in mind the need of referring each variation to a cause. But I gain the impression that the slighter prominence given to this view in the _Origin_ was not due to change of opinion, but rather because he had gradually come to take this view for granted; so that in the scheme of that book, it was overshadowed by considerations which then seemed to him more pressing. With regard to the inheritance of acquired characters I am not inclined to agree with Huxley. It is certain that the _Foundations_ contains strong recognition of the importance of germinal variation, that is of external conditions acting indirectly through the "reproductive functions." He evidently considered this as more important than the inheritance of habit or other acquired peculiarities. Another point of interest is the weight he attached in 1842-4 to "sports" or what are now called "mutations." This is I think more prominent in the _Foundations_ than in the first edition of the _Origin_, and certainly than in the fifth and sixth editions. Among other interesting points may be mentioned the "good effects of crossing" being "possibly analogous to good effects of change in condition,"--a principle which he upheld on experimental grounds in his _Cross and Self-Fertilisation_ in 1876. In conclusion, I desire to express my thanks to Mr Wallace for a footnote he was good enough to supply: and to Professor Bateson, Sir W. Thiselton-Dyer, Dr Gadow, Professor Judd, Dr Marr, Col. Prain and Dr Stapf for information on various points. I am also indebted to Mr Rutherford, of the University Library, for his careful copy of the manuscript of 1842. CAMBRIDGE, _June 9, 1909._ EXPLANATION OF SIGNS, &c. [] Means that the words so enclosed are erased in the original MS. <> Indicates an insertion by the Editor. _Origin_, Ed. vi. refers to the Popular Edition. PART I. § I. <ON VARIATION UNDER DOMESTICATION, AND ON THE PRINCIPLES OF SELECTION.> An individual organism placed under new conditions [often] sometimes varies in a small degree and in very trifling respects such as stature, fatness, sometimes colour, health, habits in animals and probably disposition. Also habits of life develope certain parts. Disuse atrophies. [Most of these slight variations tend to become hereditary.] When the individual is multiplied for long periods by buds the variation is yet small, though greater and occasionally a single bud or individual departs widely from its type (example){36} and continues steadily to propagate, by buds, such new kind. {36} Evidently a memorandum that an example should be given. When the organism is bred for several generations under new or varying conditions, the variation is greater in amount and endless in kind [especially{37} holds good when individuals have long been exposed to new conditions]. The nature of the external conditions tends to effect some definite change in all or greater part of offspring,--little food, small size--certain foods harmless &c. &c. organs affected and diseases--extent unknown. A certain degree of variation (Müller's twins){38} seems inevitable effect of process of reproduction. But more important is that simple <?> generation, especially under new conditions [when no crossing] <causes> infinite variation and not direct effect of external conditions, but only in as much as it affects the reproductive functions{39}. There seems to be no part (_beau ideal_ of liver){40} of body, internal or external, or mind or habits, or instincts which does not vary in some small degree and [often] some <?> to a great amount. {37} The importance of exposure to new conditions for several generations is insisted on in the _Origin_, Ed. i. p. 7, also p. 131. In the latter passage the author guards himself against the assumption that variations are "due to chance," and speaks of "our ignorance of the cause of each particular variation." These statements are not always remembered by his critics. {38} Cf. _Origin_, Ed. i. p. 10, vi. p. 9, "Young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Müller has remarked, have apparently been exposed to exactly the same conditions of life." {39} This is paralleled by the conclusion in the _Origin_, Ed. i. p. 8, that "the most frequent cause of variability may be attributed to the male and female reproductive elements having been affected prior to the act of conception." {40} The meaning seems to be that there must be some variability in the liver otherwise anatomists would not speak of the 'beau ideal' of that organ. [All such] variations [being congenital] or those very slowly acquired of all kinds [decidedly evince a tendency to become hereditary], when not so become simple variety, when it does a race. Each{41} parent transmits its peculiarities, therefore if varieties allowed freely to cross, except by the _chance_ of two characterized by same peculiarity happening to marry, such varieties will be constantly demolished{42}. All bisexual animals must cross, hermaphrodite plants do cross, it seems very possible that hermaphrodite animals do cross,--conclusion strengthened: ill effects of breeding in and in, good effects of crossing possibly analogous to good effects of change in condition <?>{43}. {41} The position of the following passage is uncertain. "If individuals of two widely different varieties be allowed to cross, a third race will be formed--a most fertile source of the variation in domesticated animals. <In the _Origin_, Ed. i. p. 20 the author says that "the possibility of making distinct races by crossing has been greatly exaggerated."> If freely allowed, the characters of pure parents will be lost, number of races thus <illegible> but differences <?> besides the <illegible>. But if varieties differing in very slight respects be allowed to cross, such small variation will be destroyed, at least to our senses,--a variation [clearly] just to be distinguished by long legs will have offspring not to be so distinguished. Free crossing great agent in producing uniformity in any breed. Introduce tendency to revert to parent form." {42} The swamping effect of intercrossing is referred to in the _Origin_, Ed. i. p. 103, vi. p. 126. {43} A discussion on the intercrossing of hermaphrodites in relation to Knight's views occurs in the _Origin_, Ed. i. p. 96, vi. p. 119. The parallelism between crossing and changed conditions is briefly given in the _Origin_, Ed. i. p. 267, vi. p. 391, and was finally investigated in _The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom_, 1876. Therefore if in any country or district all animals of one species be allowed freely to cross, any small tendency in them to vary will be constantly counteracted. Secondly reversion to parent form--analogue of _vis medicatrix_{44}. But if man selects, then new races rapidly formed,--of late years systematically followed,--in most ancient times often practically followed{45}. By such selection make race-horse, dray-horse--one cow good for tallow, another for eating &c.--one plant's good lay <illegible> in leaves another in fruit &c. &c.: the same plant to supply his wants at different times of year. By former means animals become adapted, as a direct effect to a cause, to external conditions, as size of body to amount of food. By this latter means they may also be so adapted, but further they may be adapted to ends and pursuits, which by no possibility can affect growth, as existence of tallow-chandler cannot tend to make fat. In such selected races, if not removed to new conditions, and <if> preserved from all cross, after several generations become very true, like each other and not varying. But man{46} selects only <?> what is useful and curious--has bad judgment, is capricious,--grudges to destroy those that do not come up to his pattern,--has no [knowledge] power of selecting according to internal variations,--can hardly keep his conditions uniform,--[cannot] does not select those best adapted to the conditions under which <the> form <?> lives, but those most useful to him. This might all be otherwise. {44} There is an article on the _vis medicatrix_ in Brougham's _Dissertations_, 1839, a copy of which is in the author's library. {45} This is the classification of selection into methodical and unconscious given in the _Origin_, Ed. i. p. 33, vi. p. 38. {46} This passage, and a similar discussion on the power of the Creator (p. 6), correspond to the comparison between the selective capacities of man and nature, in the _Origin_, Ed. i. p. 83, vi. p. 102. § II. <ON VARIATION IN A STATE OF NATURE AND ON THE NATURAL MEANS OF SELECTION.> Let us see how far above principles of variation apply to wild animals. Wild animals vary exceedingly little--yet they are known as individuals{47}. British Plants, in many genera number quite uncertain of varieties and species: in shells chiefly external conditions{48}. Primrose and cowslip. Wild animals from different [countries can be recognized]. Specific character gives some organs as varying. Variations analogous in kind, but less in degree with domesticated animals--chiefly external and less important parts. {47} i.e. they are individually distinguishable. {48} See _Origin_, Ed. i. p. 133, vi. p. 165. Our experience would lead us to expect that any and every one of these organisms would vary if <the organism were> taken away <?> and placed under new conditions. Geology proclaims a constant round of change, bringing into play, by every possible <?> change of climate and the death of pre-existing inhabitants, endless variations of new conditions. These <?> generally very slow, doubtful though <illegible> how far the slowness <?> would produce tendency to vary. But Geolog<ists> show change in configuration which, together with the accidents of air and water and the means of transportal which every being possesses, must occasionally bring, rather suddenly, organism to new conditions and <?> expose it for several generations. Hence <?> we should expect every now and then a wild form to vary{49}; possibly this may be cause of some species varying more than others. {49} When the author wrote this sketch he seems not to have been so fully convinced of the general occurrence of variation in nature as he afterwards became. The above passage in the text possibly suggests that at this time he laid more stress on _sports_ or _mutations_ than was afterwards the case. According to nature of new conditions, so we might expect all or majority of organisms born under them to vary in some definite way. Further we might expect that the mould in which they are cast would likewise vary in some small degree. But is there any means of selecting those offspring which vary in the same manner, crossing them and keeping their offspring separate and thus producing selected races: otherwise as the wild animals freely cross, so must such small heterogeneous varieties be constantly counter-balanced and lost, and a uniformity of character [kept up] preserved. The former variation as the direct and necessary effects of causes, which we can see can act on them, as size of body from amount of food, effect of certain kinds of food on certain parts of bodies &c. &c.; such new varieties may then become adapted to those external [natural] agencies which act on them. But can varieties be produced adapted to end, which cannot possibly influence their structure and which it is absurd to look <at> as effects of chance. Can varieties like some vars of domesticated animals, like almost all wild species be produced adapted by exquisite means to prey on one animal or to escape from another,--or rather, as it puts out of question effects of intelligence and habits, can a plant become adapted to animals, as a plant which cannot be impregnated without agency of insect; or hooked seeds depending on animal's existence: woolly animals cannot have any direct effect on seeds of plant. This point which all theories about climate adapting woodpecker{50} to crawl <?> up trees, <illegible> miseltoe, <sentence incomplete>. But if every part of a plant or animal was to vary <illegible>, and if a being infinitely more sagacious than man (not an omniscient creator) during thousands and thousands of years were to select all the variations which tended towards certain ends ([or were to produce causes <?> which tended to the same end]), for instance, if he foresaw a canine animal would be better off, owing to the country producing more hares, if he were longer legged and keener sight,--greyhound produced{51}. If he saw that aquatic <animal would need> skinned toes. If for some unknown cause he found it would advantage a plant, which <?> like most plants is occasionally visited by bees &c.: if that plant's seed were occasionally eaten by birds and were then carried on to rotten trees, he might select trees with fruit more agreeable to such birds as perched, to ensure their being carried to trees; if he perceived those birds more often dropped the seeds, he might well have selected a bird who would <illegible> rotten trees or [gradually select plants which <he> had proved to live on less and less rotten trees]. Who, seeing how plants vary in garden, what blind foolish man has done{52} in a few years, will deny an all-seeing being in thousands of years could effect (if the Creator chose to do so), either by his own direct foresight or by intermediate means,--which will represent <?> the creator of this universe. Seems usual means. Be it remembered I have nothing to say about life and mind and _all_ forms descending from one common type{53}. I speak of the variation of the existing great divisions of the organised kingdom, how far I would go, hereafter to be seen. {50} The author may possibly have taken the case of the woodpecker from Buffon, _Histoire Nat. des Oiseaux_, T. vii. p. 3, 1780, where however it is treated from a different point of view. He uses it more than once, see for instance _Origin_, Ed. i. pp. 3, 60, 184, vi. pp. 3, 76, 220. The passage in the text corresponds with a discussion on the woodpecker and the mistletoe in _Origin_, Ed. i. p. 3, vi. p. 3. {51} This illustration occurs in the _Origin_, Ed. i. pp. 90, 91, vi. pp. 110, 111. {52} See _Origin_, Ed. i. p. 83, vi. p. 102, where the word _Creator_ is replaced by _Nature_. {53} Note in the original. "Good place to introduce, saying reasons hereafter to be given, how far I extend theory, say to all mammalia--reasons growing weaker and weaker." Before considering whether <there> be any natural means of selection, and secondly (which forms the 2nd Part of this sketch) the far more important point whether the characters and relations of animated <things> are such as favour the idea of wild species being races <?> descended from a common stock, as the varieties of potato or dahlia or cattle having so descended, let us consider probable character of [selected races] wild varieties. _Natural Selection._ De Candolle's war of nature,--seeing contented face of nature,--may be well at first doubted; we see it on borders of perpetual cold{54}. But considering the enormous geometrical power of increase in every organism and as <?> every country, in ordinary cases <countries> must be stocked to full extent, reflection will show that this is the case. Malthus on man,--in animals no moral [check] restraint <?>--they breed in time of year when provision most abundant, or season most favourable, every country has its seasons,--calculate robins,--oscillating from years of destruction{55}. If proof were wanted let any singular change of climate <occur> here <?>, how astoundingly some tribes <?> increase, also introduced animals{56}, the pressure is always ready,--capacity of alpine plants to endure other climates,--think of endless seeds scattered abroad,--forests regaining their percentage{57},--a thousand wedges{58} are being forced into the oeconomy of nature. This requires much reflection; study Malthus and calculate rates of increase and remember the resistance,--only periodical. {54} See _Origin_, Ed. i. pp. 62, 63, vi. p. 77, where similar reference is made to De Candolle; for Malthus see _Origin_, p. 5. {55} This may possibly refer to the amount of destruction going on. See _Origin_, Ed. i. p. 68, vi. p. 84, where there is an estimate of a later date as to death-rate of birds in winter. "Calculate robins" probably refers to a calculation of the rate of increase of birds under favourable conditions. {56} In the _Origin_, Ed. i. pp. 64, 65, vi. p. 80, he instances cattle and horses and certain plants in S. America and American species of plants in India, and further on, as unexpected effects of changed conditions, the enclosure of a heath, and the relation between the fertilisation of clover and the presence of cats (_Origin_, Ed. i. p. 74, vi. p. 91). {57} _Origin_, Ed. i. p. 74, vi. p. 91. "It has been observed that the trees now growing on ... ancient Indian mounds ... display the same beautiful diversity and proportion of kinds as in the surrounding virgin forests." {58} The simile of the wedge occurs in the _Origin_, Ed. i. p. 67; it is deleted in Darwin's copy of the first edition: it does not occur in Ed. vi. The unavoidable effect of this <is> that many of every species are destroyed either in egg or [young or mature (the former state the more common)]. In the course of a thousand generations infinitesimally small differences must inevitably tell{59}; when unusually cold winter, or hot or dry summer comes, then out of the whole body of individuals of any species, if there be the smallest differences in their structure, habits, instincts [senses], health &c, <it> will on an average tell; as conditions change a rather larger proportion will be preserved: so if the chief check to increase falls on seeds or eggs, so will, in the course of 1000 generations or ten thousand, those seeds (like one with down to fly{60}) which fly furthest and get scattered most ultimately rear most plants, and such small differences tend to be hereditary like shades of expression in human countenance. So if one parent <?> fish deposits its egg in infinitesimally different circumstances, as in rather shallower or deeper water &c., it will then <?> tell. {59} In a rough summary at the close of the Essay, occur the words:--"Every creature lives by a struggle, smallest grain in balance must tell." {60} Cf. _Origin_, Ed. i. p. 77, vi. p. 94. Let hares{61} increase very slowly from change of climate affecting peculiar plants, and some other <illegible> rabbit decrease in same proportion [let this unsettle organisation of], a canine animal, who formerly derived its chief sustenance by springing on rabbits or running them by scent, must decrease too and might thus readily become exterminated. But if its form varied very slightly, the long legged fleet ones, during a thousand years being selected, and the less fleet rigidly destroyed must, if no law of nature be opposed to it, alter forms. {61} This is a repetition of what is given at p. 6. Remember how soon Bakewell on the same principle altered cattle and Western, sheep,--carefully avoiding a cross (pigeons) with any breed. We cannot suppose that one plant tends to vary in fruit and another in flower, and another in flower and foliage,--some have been selected for both fruit and flower: that one animal varies in its covering and another not,--another in its milk. Take any organism and ask what is it useful for and on that point it will be found to vary,--cabbages in their leaf,--corn in size <and> quality of grain, both in times of year,--kidney beans for young pod and cotton for envelope of seeds &c. &c.: dogs in intellect, courage, fleetness and smell <?>: pigeons in peculiarities approaching to monsters. This requires consideration,--should be introduced in first chapter if it holds, I believe it does. It is hypothetical at best{62}. {62} Compare _Origin_, Ed. i. p. 41, vi. p. 47. "I have seen it gravely remarked, that it was most fortunate that the strawberry began to vary just when gardeners began to attend closely to this plant. No doubt the strawberry had always varied since it was cultivated, but the slight varieties had been neglected." Nature's variation far less, but such selection far more rigid and scrutinising. Man's races not [even so well] only not better adapted to conditions than other races, but often not <?> one race adapted to its conditions, as man keeps and propagates some alpine plants in garden. Nature lets <an> animal live, till on actual proof it is found less able to do the required work to serve the desired end, man judges solely by his eye, and knows not whether nerves, muscles, arteries, are developed in proportion to the change of external form. Besides selection by death, in bisexual animals <illegible> the selection in time of fullest vigour, namely struggle of males; even in animals which pair there seems a surplus <?> and a battle, possibly as in man more males produced than females, struggle of war or charms{63}. Hence that male which at that time is in fullest vigour, or best armed with arms or ornaments of its species, will gain in hundreds of generations some small advantage and transmit such characters to its offspring. So in female rearing its young, the most vigorous and skilful and industrious, <whose> instincts <are> best developed, will rear more young, probably possessing her good qualities, and a greater number will thus <be> prepared for the struggle of nature. Compared to man using a male alone of good breed. This latter section only of limited application, applies to variation of [specific] sexual characters. Introduce here contrast with Lamarck,--absurdity of habit, or chance?? or external conditions, making a woodpecker adapted to tree{64}. {63} Here we have the two types of sexual selection discussed in the _Origin_, Ed. i. pp. 88 et seq., vi. pp. 108 et seq. {64} It is not obvious why the author objects to "chance" or "external conditions making a woodpecker." He allows that variation is ultimately referable to conditions and that the nature of the connexion is unknown, i.e. that the result is fortuitous. It is not clear in the original to how much of the passage the two ? refer. Before considering difficulties of theory of selection let us consider character of the races produced, as now explained, by nature. Conditions have varied slowly and the organisms best adapted in their whole course of life to the changed conditions have always been selected,--man selects small dog and afterwards gives it profusion of food,--selects a long-backed and short-legged breed and gives it no particular exercise to suit this function &c. &c. In ordinary cases nature has not allowed her race to be contaminated with a cross of another race, and agriculturists know how difficult they find always to prevent this,--effect would be trueness. This character and sterility when crossed, and generally a greater amount of difference, are two main features, which distinguish domestic races from species. [Sterility not universal admitted by all{65}. _Gladiolus_, _Crinum_, _Calceolaria_{66} must be species if there be such a thing. Races of dogs and oxen: but certainly very general; indeed a gradation of sterility most perfect{67} very general. Some nearest species will not cross (crocus, some heath <?>), some genera cross readily (fowls{68} and grouse, peacock &c.). Hybrids no ways monstrous quite perfect except secretions{69} hence even the mule has bred,--character of sterility, especially a few years ago <?> thought very much more universal than it now is, has been thought the distinguishing character; indeed it is obvious if all forms freely crossed, nature would be a chaos. But the very gradation of the character, even if it always existed in some degree which it does not, renders it impossible as marks <?> those <?> suppose distinct as species{70}]. Will analogy throw any light on the fact of the supposed races of nature being sterile, though none of the domestic ones are? Mr Herbert <and> Koelreuter have shown external differences will not guide one in knowing whether hybrids will be fertile or not, but the chief circumstance is constitutional differences{71}, such as being adapted to different climate or soil, differences which [must] probably affect the whole body of the organism and not any one part. Now wild animals, taken out of their natural conditions, seldom breed. I do not refer to shows or to Zoological Societies where many animals unite, but <do not?> breed, and others will never unite, but to wild animals caught and kept _quite tame_ left loose and well fed about houses and living many years. Hybrids produced almost as readily as pure breds. St Hilaire great distinction of tame and domestic,--elephants,--ferrets{72}. Reproductive organs not subject to disease in Zoological Garden. Dissection and microscope show that hybrid is in exactly same condition as another animal in the intervals of breeding season, or those animals which taken wild and _not bred_ in domesticity, remain without breeding their whole lives. It should be observed that so far from domesticity being unfavourable in itself <it> makes more fertile: [when animal is domesticated and breeds, productive power increased from more food and selection of fertile races]. As far as animals go might be thought <an> effect on their mind and a special case. {65} The meaning is "That sterility is not universal is admitted by all." {66} See _Var. under Dom._, Ed. 2, i. p. 388, where the garden forms of _Gladiolus_ and _Calceolaria_ are said to be derived from crosses between distinct species. Herbert's hybrid _Crinums_ are discussed in the _Origin_, Ed. i. p. 250, vi. p. 370. It is well known that the author believed in a multiple origin of domestic dogs. {67} The argument from gradation in sterility is given in the _Origin_, Ed. i. pp. 248, 255, vi. pp. 368, 375. In the _Origin_, I have not come across the cases mentioned, viz. crocus, heath, or grouse and fowl or peacock. For sterility between closely allied species, see _Origin_, Ed. i. p. 257, vi. p. 377. In the present essay the author does not distinguish between fertility between species and the fertility of the hybrid offspring, a point on which he insists in the _Origin_, Ed. i. p. 245, vi. p. 365. {68} Ackermann (_Ber. d. Vereins f. Naturkunde zu Kassel_, 1898, p. 23) quotes from Gloger that a cross has been effected between a domestic hen and a _Tetrao tetrix_; the offspring died when three days old. {69} No doubt the sexual cells are meant. I do not know on what evidence it is stated that the mule has bred. {70} The sentence is all but illegible. I think that the author refers to forms usually ranked as varieties having been marked as species when it was found that they were sterile together. See the case of the red and blue _Anagallis_ given from Gärtner in the _Origin_, Ed. i. p. 247, vi. p. 368. {71} In the _Origin_, Ed. i. p. 258, where the author speaks of constitutional differences in this connexion, he specifies that they are confined to the reproductive system. {72} The sensitiveness of the reproductive system to changed conditions is insisted on in the _Origin_, Ed. i. p. 8, vi. p. 10. The ferret is mentioned, as being prolific in captivity, in _Var. under Dom._, Ed. 2, ii. p. 90. But turning to plants we find same class of facts. I do not refer to seeds not ripening, perhaps the commonest cause, but to plants not setting, which either is owing to some imperfection of ovule or pollen. Lindley says sterility is the [curse] bane of all propagators,--Linnæus about alpine plants. American bog plants,--pollen in exactly same state as in hybrids,--same in geraniums. Persian and Chinese{73} lilac will not seed in Italy and England. Probably double plants and all fruits owe their developed parts primarily <?> to sterility and extra food thus <?> applied{74}. There is here gradation <in> sterility and then parts, like diseases, are transmitted hereditarily. We cannot assign any cause why the Pontic Azalea produces plenty of pollen and not American{75}, why common lilac seeds and not Persian, we see no difference in healthiness. We know not on what circumstances these facts depend, why ferret breeds, and cheetah{76}, elephant and pig in India will not. {73} Lindley's remark is quoted in the _Origin_, Ed. i. p. 9. Linnæus' remark is to the effect that Alpine plants tend to be sterile under cultivation (see _Var. under Dom._, Ed. 2, ii. p. 147). In the same place the author speaks of peat-loving plants being sterile in our gardens,--no doubt the American bog-plants referred to above. On the following page (p. 148) the sterility of the lilac (_Syringa persica_ and _chinensis_) is referred to. {74} The author probably means that the increase in the petals is due to a greater food supply being available for them owing to sterility. See the discussion in _Var. under Dom._, Ed. 2, ii. p. 151. It must be noted that doubleness of the flower may exist without noticeable sterility. {75} I have not come across this case in the author's works. {76} For the somewhat doubtful case of the cheetah (_Felis jubata_) see _Var. under Dom._, Ed. 2, ii. p. 133. I do not know to what fact "pig in India" refers. Now in crossing it is certain every peculiarity in form and constitution is transmitted: an alpine plant transmits its alpine tendency to its offspring, an American plant its American-bog constitution, and <with> animals, those peculiarities, on which{77} when placed out of their natural conditions they are incapable of breeding; and moreover they transmit every part of their constitution, their respiration, their pulse, their instinct, which are all suddenly modified, can it be wondered at that they are incapable of breeding? I think it may be truly said it would be more wonderful if they did. But it may be asked why have not the recognised varieties, supposed to have been produced through the means of man, [not refused to breed] have all bred{78}. Variation depends on change of condition and selection{79}, as far as man's systematic or unsystematic selection <has> gone; he takes external form, has little power from ignorance over internal invisible constitutional differences. Races which have long been domesticated, and have much varied, are precisely those which were capable of bearing great changes, whose constitutions were adapted to a diversity of climates. Nature changes slowly and by degrees. According to many authors probably breeds of dogs are another case of modified species freely crossing. There is no variety which <illegible> has been <illegible> adapted to peculiar soil or situation for a thousand years and another rigorously adapted to another, till such can be produced, the question is not tried{80}. Man in past ages, could transport into different climates, animals and plants which would freely propagate in such new climates. Nature could effect, with selection, such changes slowly, so that precisely those animals which are adapted to submit to great changes have given rise to diverse races,--and indeed great doubt on this head{81}. {77} This sentence should run "on which depends their incapacity to breed in unnatural conditions." {78} This sentence ends in confusion: it should clearly close with the words "refused to breed" in place of the bracket and the present concluding phrase. {79} The author doubtless refers to the change produced by the _summation_ of variation by means of selection. {80} The meaning of this sentence is made clear by a passage in the MS. of 1844:--"Until man selects two varieties from the same stock, adapted to two climates or to other different external conditions, and confines each rigidly for one or several thousand years to such conditions, always selecting the individuals best adapted to them, he cannot be said to have even commenced the experiment." That is, the attempt to produce mutually sterile domestic breeds. {81} This passage is to some extent a repetition of a previous one and may have been intended to replace an earlier sentence. I have thought it best to give both. In the _Origin_, Ed. i. p. 141, vi. p. 176, the author gives his opinion that the power of resisting diverse conditions, seen in man and his domestic animals, is an example "of a very common flexibility of constitution." Before leaving this subject well to observe that it was shown that a certain amount of variation is consequent on mere act of reproduction, both by buds and sexually,--is vastly increased when parents exposed for some generations to new conditions{82}, and we now find that many animals when exposed for first time to very new conditions, are <as> incapable of breeding as hybrids. It [probably] bears also on supposed fact of crossed animals when not infertile, as in mongrels, tending to vary much, as likewise seems to be the case, when true hybrids possess just sufficient fertility to propagate with the parent breeds and _inter se_ for some generations. This is Koelreuter's belief. These facts throw light on each other and support the truth of each other, we see throughout a connection between the reproductive faculties and exposure to changed conditions of life whether by crossing or exposure of the individuals{83}. {82} In the _Origin_, Ed. i. Chs. I. and V., the author does not admit reproduction, apart from environment, as being a cause of variation. With regard to the cumulative effect of new conditions there are many passages in the _Origin_, Ed. i. e.g. pp. 7, 12, vi. pp. 8, 14. {83} As already pointed out, this is the important principle investigated in the author's _Cross and Self-Fertilisation_. Professor Bateson has suggested to me that the experiments should be repeated with gametically pure individuals. _Difficulties on theory of selection_{84}. It may be objected such perfect organs as eye and ear, could never be formed, in latter less difficulty as gradations more perfect; at first appears monstrous and to <the> end appears difficulty. But think of gradation, even now manifest, (Tibia and Fibula). Everyone will allow if every fossil preserved, gradation infinitely more perfect; for possibility of selection a perfect <?> gradation is required. Different groups of structure, slight gradation in each group,--every analogy renders it probable that intermediate forms have existed. Be it remembered what strange metamorphoses; part of eye, not directly connected with vision, might come to be [thus used] gradually worked in for this end,--swimming bladder by gradation of structure is admitted to belong to the ear system,--rattlesnake. [Woodpecker best adapted to climb.] In some cases gradation not possible,--as vertebræ,--actually vary in domestic animals,--less difficult if growth followed. Looking to whole animals, a bat formed not for flight{85}. Suppose we had flying fish{86} and not one of our now called flying fish preserved, who would have guessed intermediate habits. Woodpeckers and tree-frogs both live in countries where no trees{87}. {84} In the _Origin_ a chapter is given up to "difficulties on theory": the discussion in the present essay seems slight even when it is remembered how small a space is here available. For _Tibia_ &c. see p. 48. {85} This may be interpreted "The general structure of a bat is the same as that of non-flying mammals." {86} That is truly winged fish. {87} The terrestrial woodpecker of S. America formed the subject of a paper by Darwin, _Proc. Zool. Soc._, 1870. See _Life and Letters_, vol. iii. p. 153. The gradations by which each individual organ has arrived at its present state, and each individual animal with its aggregate of organs has arrived, probably never could be known, and all present great difficulties. I merely wish to show that the proposition is not so monstrous as it at first appears, and that if good reason can be advanced for believing the species have descended from common parents, the difficulty of imagining intermediate forms of structure not sufficient to make one at once reject the theory. § III. <ON VARIATION IN INSTINCTS AND OTHER MENTAL ATTRIBUTES.> The mental powers of different animals in wild and tame state [present still greater difficulties] require a separate section. Be it remembered I have nothing to do with origin of memory, attention, and the different faculties of the mind{88}, but merely with their differences in each of the great divisions of nature. Disposition, courage, pertinacity <?>, suspicion, restlessness, ill-temper, sagacity and <the> reverse unquestionably vary in animals and are inherited (Cuba wildness dogs, rabbits, fear against particular object as man Galapagos{89}). Habits purely corporeal, breeding season &c., time of going to rest &c., vary and are hereditary, like the analogous habits of plants which vary and are inherited. Habits of body, as manner of movement d^o. and d^o. Habits, as pointing and setting on certain occasions d^o. Taste for hunting certain objects and manner of doing so,--sheep-dog. These are shown clearly by crossing and their analogy with true instinct thus shown,--retriever. Do not know objects for which they do it. Lord Brougham's definition{90}. Origin partly habit, but the amount necessarily unknown, partly selection. Young pointers pointing stones and sheep--tumbling pigeons--sheep{91} going back to place where born. Instinct aided by reason, as in the taylor-bird{92}. Taught by parents, cows choosing food, birds singing. Instincts vary in wild state (birds get wilder) often lost{93}; more perfect,--nest without roof. These facts [only clear way] show how incomprehensibly brain has power of transmitting intellectual operations. {88} The same proviso occurs in the _Origin_, Ed. i. p. 207, vi. p. 319. {89} The tameness of the birds in the Galapagos is described in the _Journal of Researches_ (1860), p. 398. Dogs and rabbits are probably mentioned as cases in which the hereditary fear of man has been lost. In the 1844 MS. the author states that the Cuban feral dog shows great natural wildness, even when caught quite young. {90} In the _Origin_, Ed. i. p. 207, vi. p. 319, he refuses to define instinct. For Lord Brougham's definition see his _Dissertations on Subjects of Science etc._, 1839, p. 27. {91} See James Hogg (the Ettrick Shepherd), Works, 1865, _Tales and Sketches_, p. 403. {92} This refers to the tailor-bird making use of manufactured thread supplied to it, instead of thread twisted by itself. {93} _Often lost_ applies to _instinct_: _birds get wilder_ is printed in a parenthesis because it was apparently added as an after-thought. _Nest without roof_ refers to the water-ousel omitting to vault its nest when building in a protected situation. Faculties{94} distinct from true instincts,--finding [way]. It must I think be admitted that habits whether congenital or acquired by practice [sometimes] often become inherited{95}; instincts, influence, equally with structure, the preservation of animals; therefore selection must, with changing conditions tend to modify the inherited habits of animals. If this be admitted it will be found _possible_ that many of the strangest instincts may be thus acquired. I may observe, without attempting definition, that an inherited habit or trick (trick because may be born) fulfils closely what we mean by instinct. A habit is often performed unconsciously, the strangest habits become associated, d^o. tricks, going in certain spots &c. &c., even against will, is excited by external agencies, and looks not to the end,--a person playing a pianoforte. If such a habit were transmitted it would make a marvellous instinct. Let us consider some of the most difficult cases of instincts, whether they could be _possibly_ acquired. I do not say _probably_, for that belongs to our 3rd Part{96}, I beg this may be remembered, nor do I mean to attempt to show exact method. I want only to show that whole theory ought not at once to be rejected on this score. {94} In the MS. of 1844 is an interesting discussion on _faculty_ as distinct from _instinct_. {95} At this date and for long afterwards the inheritance of acquired characters was assumed to occur. {96} Part II. is here intended: see the Introduction. Every instinct must, by my theory, have been acquired gradually by slight changes <illegible> of former instinct, each change being useful to its then species. Shamming death struck me at first as remarkable objection. I found none really sham death{97}, and that there is gradation; now no one doubts that those insects which do it either more or less, do it for some good, if then any species was led to do it more, and then <?> escaped &c. &c. {97} The meaning is that the attitude assumed in _shamming_ is not accurately like that of death. Take migratory instincts, faculty distinct from instinct, animals have notion of time,--like savages. Ordinary finding way by memory, but how does savage find way across country,--as incomprehensible to us, as animal to them,--geological changes,--fishes in river,--case of sheep in Spain{98}. Architectural instincts,--a manufacturer's employee in making single articles extraordinary skill,--often said seem to make it almost <illegible>, child born with such a notion of playing{99},--we can fancy tailoring acquired in same perfection,--mixture of reason,--water-ouzel,--taylor-bird,--gradation of simple nest to most complicated. {98} This refers to the _transandantes_ sheep mentioned in the MS. of 1844, as having acquired a migratory instinct. {99} In the _Origin_, Ed. i. p. 209, vi. p. 321, Mozart's pseudo-instinctive skill in piano-playing is mentioned. See _Phil. Trans._, 1770, p. 54. Bees again, distinction of faculty,--how they make a hexagon,--Waterhouse's theory{100},--the impulse to use whatever faculty they possess,--the taylor-bird has the faculty of sewing with beak, instinct impels him to do it. {100} In the discussion on bees' cells, _Origin_, Ed. i. p. 225, vi. p. 343, the author acknowledges that his theory originated in Waterhouse's observations. Last case of parent feeding young with different food (take case of Galapagos birds, gradation from Hawfinch to Sylvia) selection and habit might lead old birds to vary taste <?> and form, leaving their instinct of feeding their young with same food{101},--or I see no difficulty in parents being forced or induced to vary the food brought, and selection adapting the young ones to it, and thus by degree any amount of diversity might be arrived at. Although we can never hope to see the course revealed by which different instincts have been acquired, for we have only present animals (not well known) to judge of the course of gradation, yet once grant the principle of habits, whether congenital or acquired by experience, being inherited and I can see no limit to the [amount of variation] extraordinariness <?> of the habits thus acquired. {101} The hawfinch-and _Sylvia-_types are figured in the _Journal of Researches_, p. 379. The discussion of change of form in relation to change of instinct is not clear, and I find it impossible to suggest a paraphrase. _Summing up this Division._ If variation be admitted to occur occasionally in some wild animals, and how can we doubt it, when we see [all] thousands <of> organisms, for whatever use taken by man, do vary. If we admit such variations tend to be hereditary, and how can we doubt it when we <remember> resemblances of features and character,--disease and monstrosities inherited and endless races produced (1200 cabbages). If we admit selection is steadily at work, and who will doubt it, when he considers amount of food on an average fixed and reproductive powers act in geometrical ratio. If we admit that external conditions vary, as all geology proclaims, they have done and are now doing,--then, if no law of nature be opposed, there must occasionally be formed races, [slightly] differing from the parent races. So then any such law{102}, none is known, but in all works it is assumed, in <?> flat contradiction to all known facts, that the amount of possible variation is soon acquired. Are not all the most varied species, the oldest domesticated: who <would> think that horses or corn could be produced? Take dahlia and potato, who will pretend in 5000 years{103} <that great changes might not be effected>: perfectly adapted to conditions and then again brought into varying conditions. Think what has been done in few last years, look at pigeons, and cattle. With the amount of food man can produce he may have arrived at limit of fatness or size, or thickness of wool <?>, but these are the most trivial points, but even in these I conclude it is impossible to say we know the limit of variation. And therefore with the [adapting] selecting power of nature, infinitely wise compared to those of man, <I conclude> that it is impossible to say we know the limit of races, which would be true <to their> kind; if of different constitutions would probably be infertile one with another, and which might be adapted in the most singular and admirable manner, according to their wants, to external nature and to other surrounding organisms,--such races would be species. But is there any evidence <that> species <have> been thus produced, this is a question wholly independent of all previous points, and which on examination of the kingdom of nature <we> ought to answer one way or another. {102} I should interpret this obscure sentence as follows, "No such opposing law is known, but in all works on the subject a law is (in flat contradiction to all known facts) assumed to limit the possible amount of variation." In the _Origin_, the author never limits the power of variation, as far as I know. {103} In _Var. under Dom._ Ed. 2, ii. p. 263, the _Dahlia_ is described as showing sensitiveness to conditions in 1841. All the varieties of the _Dahlia_ are said to have arisen since 1804 (_ibid._ i. p. 393). PART II{104}. {104} In the original MS. the heading is: Part III.; but Part II. is clearly intended; for details see the Introduction. I have not been able to discover where § IV. ends and § V. begins. §§ IV. & V. <ON THE EVIDENCE FROM GEOLOGY.> I may premise, that according to the view ordinarily received, the myriads of organisms peopling this world have been created by so many distinct acts of creation. As we know nothing of the <illegible> will of a Creator,--we can see no reason why there should exist any relation between the organisms thus created; or again, they might be created according to any scheme. But it would be marvellous if this scheme should be the same as would result from the descent of groups of organisms from [certain] the same parents, according to the circumstances, just attempted to be developed. With equal probability did old cosmogonists say fossils were created, as we now see them, with a false resemblance to living beings{105}; what would the Astronomer say to the doctrine that the planets moved <not> according to the law of gravitation, but from the Creator having willed each separate planet to move in its particular orbit? I believe such a proposition (if we remove all prejudices) would be as legitimate as to admit that certain groups of living and extinct organisms, in their distribution, in their structure and in their relations one to another and to external conditions, agreed with the theory and showed signs of common descent, and yet were created distinct. As long as it was thought impossible that organisms should vary, or should anyhow become adapted to other organisms in a complicated manner, and yet be separated from them by an impassable barrier of sterility{106}, it was justifiable, even with some appearance in favour of a common descent, to admit distinct creation according to the will of an Omniscient Creator; or, for it is the same thing, to say with Whewell that the beginnings of all things surpass the comprehension of man. In the former sections I have endeavoured to show that such variation or specification is not impossible, nay, in many points of view is absolutely probable. What then is the evidence in favour of it and what the evidence against it. With our imperfect knowledge of past ages [surely there will be some] it would be strange if the imperfection did not create some unfavourable evidence. {105} This passage corresponds roughly to the conclusion of the _Origin_, see Ed. i. p. 482, vi. p. 661. {106} A similar passage occurs in the conclusion of the _Origin_, Ed. i. p. 481, vi. p. 659. Give sketch of the Past,--beginning with facts appearing hostile under present knowledge,--then proceed to geograph. distribution,--order of appearance,--affinities,--morphology &c., &c. Our theory requires a very gradual introduction of new forms{107}, and extermination of the old (to which we shall revert). The extermination of old may sometimes be rapid, but never the introduction. In the groups descended from common parent, our theory requires a perfect gradation not differing more than breed<s> of cattle, or potatoes, or cabbages in forms. I do not mean that a graduated series of animals must have existed, intermediate between horse, mouse, tapir{108}, elephant [or fowl and peacock], but that these must have had a common parent, and between horse and this <?> parent &c., &c., but the common parent may possibly have differed more from either than the two do now from each other. Now what evidence of this is there? So perfect gradation in some departments, that some naturalists have thought that in some large divisions, if all existing forms were collected, a near approach to perfect gradation would be made. But such a notion is preposterous with respect to all, but evidently so with mammals. Other naturalists have thought this would be so if all the specimens entombed in the strata were collected{109}. I conceive there is no probability whatever of this; nevertheless it is certain all the numerous fossil forms fall in<to>, as Buckland remarks, _not_ present classes, families and genera, they fall between them: so is it with new discoveries of existing forms. Most ancient fossils, that is most separated <by> space of time, are most apt to fall between the classes--(but organisms from those countries most separated by space also fall between the classes <_e.g._> Ornithorhyncus?). As far as geological discoveries <go> they tend towards such gradation{110}. Illustrate it with net. Toxodon,--tibia and fibula,--dog and otter,--but so utterly improbable is <it>, in _ex. gr._ Pachydermata, to compose series as perfect as cattle, that if, as many geologists seem to infer, each separate formation presents even an approach to a consecutive history, my theory must be given up. Even if it were consecutive, it would only collect series of one district in our present state of knowledge; but what probability is there that any one formation during the _immense_ period which has elapsed during each period will _generally_ present a consecutive history. [Compare number living at one period to fossils preserved--look at enormous periods of time.] {107} See _Origin_, Ed. i. p. 312, vi. p. 453. {108} See _Origin_, Ed. i. pp. 280, 281, vi. p. 414. The author uses his experience of pigeons for examples for what he means by _intermediate_; the instance of the horse and tapir also occurs. {109} The absence of intermediate forms between living organisms (and also as regards fossils) is discussed in the _Origin_, Ed. i. pp. 279, 280, vi. p. 413. In the above discussion there is no evidence that the author felt this difficulty so strongly as it is expressed in the _Origin_, Ed. i. p. 299,--as perhaps "the most obvious and gravest objection that can be urged against my theory." But in a rough summary written on the back of the penultimate page of the MS. he refers to the geological evidence:--"Evidence, as far as it does go, is favourable, exceedingly incomplete,--greatest difficulty on this theory. I am convinced not insuperable." Buckland's remarks are given in the _Origin_, Ed. i. p. 329, vi. p. 471. {110} That the evidence of geology, as far as it goes, is favourable to the theory of descent is claimed in the _Origin_, Ed. i. pp. 343-345, vi. pp. 490-492. For the reference to _net_ in the following sentence, see Note 1, p. 48, {Note 161} of this Essay. Referring only to marine animals, which are obviously most likely to be preserved, they must live where <?> sediment (of a kind favourable for preservation, not sand and pebble){111} is depositing quickly and over large area and must be thickly capped, <illegible> littoral deposits: for otherwise denudation <will destroy them>,--they must live in a shallow space which sediment will tend to fill up,--as movement is <in?> progress if soon brought <?> up <?> subject to denudation,--[if] as during subsidence favourable, accords with facts of European deposits{112}, but subsidence apt to destroy agents which produce sediment{113}. {111} See _Origin_, Ed. i. p. 288, vi. p. 422. "The remains that do become embedded, if in sand and gravel, will, when the beds are upraised, generally be dissolved by the percolation of rain-water." {112} The position of the following is not clear:--"Think of immense differences in nature of European deposits,--without interposing new causes,--think of time required by present slow changes, to cause, on very same area, such diverse deposits, iron-sand, chalk, sand, coral, clay!" {113} The paragraph which ends here is difficult to interpret. In spite of obscurity it is easy to recognize the general resemblance to the discussion on the importance of subsidence given in the _Origin_, Ed. i. pp. 290 et seq., vi. pp. 422 et seq. I believe safely inferred <that> groups of marine <?> fossils only preserved for future ages where sediment goes on long <and> continuous<ly> and with rapid but not too rapid deposition in <an> area of subsidence. In how few places in any one region like Europe will <?> these contingencies be going on? Hence <?> in past ages mere [gaps] pages preserved{114}. Lyell's doctrine carried to extreme,--we shall understand difficulty if it be asked:--what chance of series of gradation between cattle by <illegible> at age <illegible> as far back as Miocene{115}? We know then cattle existed. Compare number of living,--immense duration of each period,--fewness of fossils. {114} See Note 3, p. 27. {115} Compare _Origin_, Ed. i. p. 298, vi. p. 437. "We shall, perhaps, best perceive the improbability of our being enabled to connect species by numerous, fine, intermediate, fossil links, by asking ourselves whether, for instance, geologists at some future period will be able to prove that our different breeds of cattle, sheep, horses, and dogs have descended from a single stock or from several aboriginal stocks." This only refers to consecutiveness of history of organisms of each formation. The foregoing argument will show firstly, that formations are distinct merely from want of fossils <of intermediate beds>, and secondly, that each formation is full of gaps, has been advanced to account for _fewness_ of _preserved_ organisms compared to what have lived on the world. The very same argument explains why in older formations the organisms appear to come on and disappear suddenly,--but in [later] tertiary not quite suddenly{116}, in later tertiary gradually,--becoming rare and disappearing,--some have disappeared within man's time. It is obvious that our theory requires gradual and nearly uniform introduction, possibly more sudden extermination,--subsidence of continent of Australia &c., &c. {116} The sudden appearance of groups of allied species in the lowest known fossiliferous strata is discussed in the _Origin_, Ed. i. p. 306, vi. p. 446. The gradual appearance in the later strata occurs in the _Origin_, Ed. i. p. 312, vi. p. 453. Our theory requires that the first form which existed of each of the great divisions would present points intermediate between existing ones, but immensely different. Most geologists believe Silurian{117} fossils are those which first existed in the whole world, not those which have chanced to be the oldest not destroyed,--or the first which existed in profoundly deep seas in progress of conversion from sea to land: if they are first they <? we> give up. Not so Hutton or Lyell: if first reptile{118} of Red Sandstone <?> really was first which existed: if Pachyderm{119} of Paris was first which existed: fish of Devonian: dragon fly of Lias: for we cannot suppose them the progenitors: they agree too closely with existing divisions. But geologists consider Europe as <?> a passage from sea to island <?> to continent (except Wealden, see Lyell). These animals therefore, I consider then mere introduction <?> from continents long since submerged. {117} Compare _Origin_, Ed. i. p. 307, vi. p. 448. {118} I have interpreted as _Sandstone_ a scrawl which I first read as _Sea_; I have done so at the suggestion of Professor Judd, who points out that "footprints in the red sandstone were known at that time, and geologists were not then particular to distinguish between Amphibians and Reptiles." {119} This refers to Cuvier's discovery of _Palæotherium_ &c. at Montmartre. Finally, if views of some geologists be correct, my theory must be given up. [Lyell's views, as far as they go, are in _favour_, but they go so little in favour, and so much more is required, that it may <be> viewed as objection.] If geology present us with mere pages in chapters, towards end of <a> history, formed by tearing out bundles of leaves, and each page illustrating merely a small portion of the organisms of that time, the facts accord perfectly with my theory{120}. {120} This simile is more fully given in the _Origin_, Ed. i. p. 310, vi. p. 452. "For my part, following out Lyell's metaphor, I look at the natural geological record, as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines. Each word of the slowly-changing language, in which the history is supposed to be written, being more or less different in the interrupted succession of chapters, may represent the apparently abruptly changed forms of life, entombed in our consecutive, but widely separated formations." Professor Judd has been good enough to point out to me, that Darwin's metaphor is founded on the comparison of geology to history in Ch. i. of the _Principles of Geology_, Ed. i. 1830, vol. i. pp. 1-4. Professor Judd has also called my attention to another passage,--_Principles_, Ed. i. 1833, vol. iii. p. 33, when Lyell imagines an historian examining "two buried cities at the foot of Vesuvius, immediately superimposed upon each other." The historian would discover that the inhabitants of the lower town were Greeks while those of the upper one were Italians. But he would be wrong in supposing that there had been a sudden change from the Greek to the Italian language in Campania. I think it is clear that Darwin's metaphor is partly taken from this passage. See for instance (in the above passage from the _Origin_) such phrases as "history ... written in a changing dialect"--"apparently abruptly changed forms of life." The passage within [] in the above paragraph:--"Lyell's views as far as they go &c.," no doubt refers, as Professor Judd points out, to Lyell not going so far as Darwin on the question of the imperfection of the geological record. _Extermination._ We have seen that in later periods the organisms have disappeared by degrees and [perhaps] probably by degrees in earlier, and I have said our theory requires it. As many naturalists seem to think extermination a most mysterious circumstance{121} and call in astonishing agencies, it is well to recall what we have shown concerning the struggle of nature. An exterminating agency is at work with every organism: we scarcely see it: if robins would increase to thousands in ten years how severe must the process be. How imperceptible a small increase: fossils become rare: possibly sudden extermination as Australia, but as present means very slow and many means of escape, I shall doubt very sudden exterminations. Who can explain why some species abound more,--why does marsh titmouse, or ring-ouzel, now little change,--why is one sea-slug rare and another common on our coasts,--why one species of Rhinoceros more than another,--why is <illegible> tiger of India so rare? Curious and general sources of error, the place of an organism is instantly filled up. {121} On rarity and extinction see _Origin_, Ed. i. pp. 109, 319, vi. pp. 133, 461. We know state of earth has changed, and as earthquakes and tides go on, the state must change,--many geologists believe a slow gradual cooling. Now let us see in accordance with principles of [variation] specification explained in Sect. II. how species would probably be introduced and how such results accord with what is known. The first fact geology proclaims is immense number of extinct forms, and new appearances. Tertiary strata leads to belief, that forms gradually become rare and disappear and are gradually supplied by others. We see some forms now becoming rare and disappearing, we know of no sudden creation: in older periods the forms _appear_ to come in suddenly, scene shifts: but even here Devonian, Permian &c. [keep on supplying new links in chain]--Genera and higher forms come on and disappear, in same way leaving a species on one or more stages below that in which the form abounded. <GEOGRAPHICAL DISTRIBUTION.> § VI. Let us consider the absolute state of distribution of organisms of earth's face. Referring chiefly, but not exclusively (from difficulty of transport, fewness, and the distinct characteristics of groups) to Mammalia; and first considering the three or four main [regions] divisions; North America, Europe, Asia, including greater part of E. Indian Archipelago and Africa are intimately allied. Africa most distinct, especially most southern parts. And the Arctic regions, which unite N. America, Asia and Europe, only separated (if we travel one way by Behring's St.) by a narrow strait, is most intimately allied, indeed forms but one restricted group. Next comes S. America,--then Australia, Madagascar (and some small islands which stand very remote from the land). Looking at these main divisions separately, the organisms vary according to changes in condition{122} of different parts. But besides this, barriers of every kind seem to separate regions in a greater degree than proportionally to the difference of climates on each side. Thus great chains of mountains, spaces of sea between islands and continents, even great rivers and deserts. In fact the amount <of> difference in the organisms bears a certain, but not invariable relation to the amount of physical difficulties to transit{123}. {122} In the _Origin_, Ed. i. p. 346, vi. p. 493, the author begins his discussion on geographical distribution by minimising the effect of physical conditions. He lays great stress on the effect of _barriers_, as in the present Essay. {123} Note in the original, "Would it be more striking if we took animals, take Rhinoceros, and study their habitats?" There are some curious exceptions, namely, similarity of fauna of mountains of Europe and N. America and Lapland. Other cases just <the> reverse, mountains of eastern S. America, Altai <?>, S. India <?>{124}: mountain summits of islands often eminently peculiar. Fauna generally of some islands, even when close, very dissimilar, in others very similar. [I am here led to observe one or more centres of creation{125}.] {124} Note by Mr A. R. Wallace. "The want of similarity referred to, is, between the mountains of Brazil and Guiana and those of the Andes. Also those of the Indian peninsula as compared with the Himalayas. In both cases there is continuous intervening land. "The islands referred to were, no doubt, the Galapagos for dissimilarity from S. America; our own Islands as compared with Europe, and perhaps Java, for similarity with continental Asia." {125} The arguments against multiple centres of creation are given in the _Origin_, Ed. i. p. 352, vi. p. 499. The simple geologist can explain many of the foregoing cases of distribution. Subsidence of a continent in which free means of dispersal, would drive the lowland plants up to the mountains, now converted into islands, and the semi-alpine plants would take place of alpine, and alpine be destroyed, if mountains originally were not of great height. So we may see, during gradual changes{126} of climate on a continent, the propagation of species would vary and adapt themselves to small changes causing much extermination{127}. The mountains of Europe were quite lately covered with ice, and the lowlands probably partaking of the Arctic climate and Fauna. Then as climate changed, arctic fauna would take place of ice, and an inundation of plants from different temperate countries <would> seize the lowlands, leaving islands of arctic forms. But if this had happened on an island, whence could the new forms have come,--here the geologist calls in creationists. If island formed, the geologist will suggest <that> many of the forms might have been borne from nearest land, but if peculiar, he calls in creationist,--as such island rises in height &c., he still more calls in creation. The creationist tells one, on a <illegible> spot the American spirit of creation makes _Orpheus_ and _Tyrannus_ and American doves, and in accordance with past and extinct forms, but no persistent relation between areas and distribution, Geologico-Geograph.-Distribution. {126} In the _Origin_, Ed. i. p. 366, vi. p. 516, the author does not give his views on the distribution of alpine plants as original but refers to Edward Forbes' work (_Geolog. Survey Memoirs_, 1846). In his autobiography, Darwin refers to this. "I was forestalled" he says, "in only one important point, which my vanity has always made me regret." (_Life and Letters_, i. p. 88.) {127} <The following is written on the back of a page of the MS.> Discuss one or more centres of creation: allude strongly to facilities of dispersal and amount of geological change: allude to mountain-summits afterwards to be referred to. The distribution varies, as everyone knows, according to adaptation, explain going from N. to S. how we come to fresh groups of species in the same general region, but besides this we find difference, according to greatness of barriers, in greater proportion than can be well accounted for by adaptation. <On representive species see _Origin_, Ed. i. p. 349, vi. p. 496.> This very striking when we think of cattle of Pampas, plants <?> &c. &c. Then go into discussion; this holds with 3 or 4 main divisions as well as the endless minor ones in each of these 4 great ones: in these I chiefly refer to mammalia &c. &c. The similarity of type, but not in species, in same continent has been much less insisted on than the dissimilarity of different great regions generically: it is more striking. <I have here omitted an incomprehensible sentence.> Galapagos Islands, Tristan d'Acunha, _volcanic_ islands covered with craters we know lately did not support any organisms. How unlike these islands in nature to neighbouring lands. These facts perhaps more striking than almost any others. [Geology apt to affect geography therefore we ought to expect to find the above.] Geological-geographical distribution. In looking to past times we find Australia equally distinct. S. America was distinct, though with more forms in common. N. America its nearest neighbour more in common,--in some respects more, in some less allied to Europe. Europe we find <?> equally European. For Europe is now part of Asia though not <illegible>. Africa unknown,--examples, Elephant, Rhinoceros, Hippopotamus, Hyaena. As geology destroys geography we cannot be surprised in going far back we find Marsupials and Edentata in Europe: but geology destroys geography. Now according to analogy of domesticated animals let us see what would result. Let us take case of farmer on Pampas, where everything approaches nearer to state of nature. He works on organisms having strong tendency to vary: and he knows <that the> only way to make a distinct breed is to select and separate. It would be useless to separate the best bulls and pair with best cows if their offspring run loose and bred with the other herds, and tendency to reversion not counteracted; he would endeavour therefore to get his cows on islands and then commence his work of selection. If several farmers in different _rincons_{128} were to set to work, especially if with different objects, several breeds would soon be produced. So would it be with horticulturist and so history of every plant shows; the number of varieties{129} increase in proportion to care bestowed on their selection and, with crossing plants, separation. Now, according to this analogy, change of external conditions, and isolation either by chance landing <of> a form on an island, or subsidence dividing a continent, or great chain of mountains, and the number of individuals not being numerous will best favour variation and selection{130}. No doubt change could be effected in same country without any barrier by long continued selection on one species: even in case of a plant not capable of crossing would easier get possession and solely occupy an island{131}. Now we can at once see that <if> two parts of a continent isolated, new species thus generated in them, would have closest affinities, like cattle in counties of England: if barrier afterwards destroyed one species might destroy the other or both keep their ground. So if island formed near continent, let it be ever so different, that continent would supply inhabitants, and new species (like the old) would be allied with that continent. An island generally very different soil and climate, and number and order of inhabitants supplied by chance, no point so favourable for generation of new species{132},--especially the mountains, hence, so it is. As isolated mountains formed in a plain country (if such happens) is an island. As other islands formed, the old species would spread and thus extend and the fauna of distant island might ultimately meet and a continent formed between them. No one doubts continents formed by repeated elevations and depressions{133}. In looking backwards, but not so far that all geographical boundaries are destroyed, we can thus at once see why existing forms are related to the extinct in the same manner as existing ones are in some part of existing continent. By chance we might even have one or two absolute parent fossils. {128} _Rincon_ in Spanish means a _nook_ or _corner_, it is here probably used to mean a small farm. {129} The following is written across the page: "No one would expect a set of similar varieties to be produced in the different countries, so species different." {130} <The following passage seems to have been meant to follow here.> The parent of an organism, we may generally suppose to be in less favourable condition than the selected offspring and therefore generally in fewer numbers. (This is not borne out by horticulture, mere hypothesis; as an organism in favourable conditions might by selection be adapted to still more favourable conditions.) Barrier would further act in preventing species formed in one part migrating to another part. {131} <The following notes occur on the back of the page.> Number of species not related to capabilities of the country: furthermore not always those best adapted, perhaps explained by creationists by changes and progress. <See p. 34, note 1.{Note 134}> Although creationists can, by help of geology, explain much, how can he explain the marked relation of past and present in same area, the varying relation in other cases, between past and present, the relation of different parts of same great area. If island, to adjoining continent, if quite different, on mountain summits,--the number of individuals not being related to capabilities, or how &c.--our theory, I believe, can throw much light and all facts accord. {132} See _Origin_, Ed. i. p. 390, vi. p. 543. {133} On oscillation see _Origin_, Ed. i. p. 291, vi. p. 426. The detection of transitional forms would be rendered more difficult on rising point of land. The distribution therefore in the above enumerated points, even the trivial ones, which on any other <theory?> can be viewed as so many ultimate facts, all follow <in> a simple manner on the theory of the occurrence of species by <illegible> and being adapted by selection to <illegible>, conjoined with their power of dispersal, and the steady geographico-geological changes which are now in progress and which undoubtedly have taken place. Ought to state the opinion of the immutability of species and the creation by so many separate acts of will of the Creator{134}. {134} <From the back of MS.> Effect of climate on stationary island and on continent, but continent once island. Moreover repeated oscillations fresh diffusion when non-united, then isolation, when rising again immigration prevented, new habitats formed, new species, when united free immigration, hence uniform characters. Hence more forms <on?> the island. Mountain summits. Why not true species. First let us recall in Part I, conditions of variation: change of conditions during several generations, and if frequently altered so much better [perhaps excess of food]. Secondly, continued selection [while in wild state]. Thirdly, isolation in all or nearly all,--as well to recall advantages of. [In continent, if we look to terrestrial animal, long continued change might go on, which would only cause change in numerical number <? proportions>: if continued long enough might ultimately affect all, though to most continents <there is> chance of immigration. Some few of whole body of species must be long affected and entire selection working same way. But here isolation absent, without barrier, cut off such <illegible>. We can see advantage of isolation. But let us take case of island thrown up by volcanic agency at some distances, here we should have occasional visitants, only in few numbers and exposed to new conditions and <illegible> more important,--a quite new grouping of organic beings, which would open out new sources of subsistence, or <would> control <?> old ones. The number would be few, can old have the very best opportunity. <The conquest of the indigenes by introduced organisms shows that the indigenes were not perfectly adapted, see _Origin_, Ed. i. p. 390.> Moreover as the island continued changing,--continued slow changes, river, marshes, lakes, mountains &c. &c., new races as successively formed and a fresh occasional visitant. If island formed continent, some species would emerge and immigrate. Everyone admits continents. We can see why Galapagos and C. Verde differ <see _Origin_, Ed. i. p. 398>], depressed and raised. We can see from this repeated action and the time required for a continent, why many more forms than in New Zealand <see _Origin_, Ed. i. p. 389 for a comparison between New Zealand and the Cape> no mammals or other classes <see however, _Origin_, Ed. i. p. 393 for the case of the frog>. We can at once see how it comes when there has been an old channel of migration,--Cordilleras; we can see why Indian Asiatic Flora,--[why species] having a wide range gives better chance of some arriving at new points and being selected, and adapted to new ends. I need hardly remark no necessity for change. Finally, as continent (most extinction <?> during formation of continent) is formed after repeated elevation and depression, and interchange of species we might foretell much extinction, and that the survivor would belong to same type, as the extinct, in same manner as different part of same continent, which were once separated by space as they are by time <see _Origin_, Ed. i. pp. 339 and 349>. As all mammals have descended from one stock, we ought to expect that every continent has been at some time connected, hence obliteration of present ranges. I do not mean that the fossil mammifers found in S. America are the lineal successors <ancestors> of the present forms of S. America: for it is highly improbable that more than one or two cases (who will say how many races after Plata bones) should be found. I believe this from numbers, who have lived,--mere <?> chance of fewness. Moreover in every case from very existence of genera and species only few at one time will leave progeny, under form of new species, to distant ages; and the more distant the ages the fewer the progenitors. An observation may be here appended, bad chance of preservation on rising island, the nurseries of new species, appeal to experience <see _Origin_, Ed. i. p. 292>. This observation may be extended, that in all cases, subsiding land must be, in early stages, less favourable to formation of new species; but it will isolate them, and then if land recommences rising how favourable. As preoccupation is bar to diffusion to species, so would it be to a selected variety. But it would not be if that variety was better fitted to some not fully occupied station; so during elevation or the formation of new stations, is scene for new species. But during elevation not favourable to preservation of fossil (except in caverns <?>); when subsidence highly favourable in early stages to preservation of fossils; when subsidence, less sediment. So that our strata, as general rule will be the tomb of old species (not undergoing any change) when rising land the nursery. But if there be vestige will generally be preserved to future ages, the new ones will not be entombed till fresh subsidence supervenes. In this long gap we shall have no record: so that wonderful if we should get transitional forms. I do not mean every stage, for we cannot expect that, as before shown, until geologists will be prepared to say that although under unnaturally favourable condition we can trace in future ages short-horn and Herefordshire <see note 2, p. 26>. {Note 115} § VII. <AFFINITIES AND CLASSIFICATION.> Looking now to the affinities of organisms, without relation to their distribution, and taking all fossil and recent, we see the degrees of relationship are of different degrees and arbitrary,--sub-genera,--genera,--sub-families, families, orders and classes and kingdoms. The kind of classification which everyone feels is most correct is called the natural system, but no can define this. If we say with Whewell <that we have an> undefined instinct of the importance of organs{135}, we have no means in lower animals of saying which is most important, and yet everyone feels that some one system alone deserves to be called natural. The true relationship of organisms is brought before one by considering relations of analogy, an otter-like animal amongst mammalia and an otter amongst marsupials. In such cases external resemblance and habit of life and _the final end of whole organization_ very strong, yet no relation{136}. Naturalists cannot avoid these terms of relation and affinity though they use them metaphorically. If used in simple earnestness the natural system ought to be a genealogical <one>; and our knowledge of the points which are most easily affected in transmission are those which we least value in considering the natural system, and practically when we find they do vary we regard them of less value{137}. In classifying varieties the same language is used and the same kind of division: here also (in pine-apple){138} we talk of the natural classification, overlooking similarity of the fruits, because whole plant differs. The origin of sub-genera, genera, &c., &c., is not difficult on notion of genealogical succession, and accords with what we know of similar gradations of affinity in domesticated organisms. In the same region the organic beings are <illegible> related to each other and the external conditions in many physical respects are allied{139} and their differences of same kind, and therefore when a new species has been selected and has obtained a place in the economy of nature, we may suppose that generally it will tend to extend its range during geographical changes, and thus, becoming isolated and exposed to new conditions, will slightly alter and its structure by selection become slightly remodified, thus we should get species of a sub-genus and genus,--as varieties of merino-sheep,--varieties of British and Indian cattle. Fresh species might go on forming and others become extinct and all might become extinct, and then we should have <an> extinct genus; a case formerly mentioned, of which numerous cases occur in Palæontology. But more often the same advantages which caused the new species to spread and become modified into several species would favour some of the species being preserved: and if two of the species, considerably different, each gave rise to group of new species, you would have two genera; the same thing will go on. We may look at case in other way, looking to future. According to mere chance every existing species may generate another, but if any species, A, in changing gets an advantage and that advantage (whatever it may be, intellect, &c., &c., or some particular structure or constitution) is inherited{140}, A will be the progenitor of several genera or even families in the hard struggle of nature. A will go on beating out other forms, it might come that A would people earth,--we may now not have one descendant on our globe of the one or several original creations{141}. External conditions air, earth, water being same{142} on globe, and the communication not being perfect, organisms of widely different descent might become adapted to the same end and then we should have cases of analogy{143}, [they might even tend to become numerically representative]. From this often happening each of the great divisions of nature would have their representative eminently adapted to earth, to <air>{144}, to water, and to these in <illegible> and then these great divisions would show numerical relations in their classification. {135} After "organs" is inserted, apparently as an afterthought:--"no, and instance metamorphosis, afterwards explicable." {136} For analogical resemblances see _Origin_, Ed. i. p. 427, vi. p. 582. {137} "Practically when naturalists are at work, they do not trouble themselves about the physiological value of the characters.... If they find a character nearly uniform, ... they use it as one of high value," _Origin_, Ed. i. p. 417, vi. p. 573. {138} "We are cautioned ... not to class two varieties of the pine-apple together, merely because their fruit, though the most important part, happens to be nearly identical," _Origin_, Ed. i. p. 423, vi. p. 579. {139} The whole of this passage is obscure, but the text is quite clear, except for one illegible word. {140} <The exact position of the following passage is uncertain:> "just as it is not likely every present breed of fancy birds and cattle will propagate, only some of the best." {141} This suggests that the author was not far from the principle of divergence on which he afterwards laid so much stress. See _Origin_, Ed. i. p. 111, vi. p. 134, also _Life and Letters_, i. p. 84. {142} That is to say the same conditions occurring in different parts of the globe. {143} The position of the following is uncertain, "greyhound and racehorse have an analogy to each other." The same comparison occurs in the _Origin_, Ed. i. p. 427, vi. p. 583. {144} _Air_ is evidently intended; in the MS. _water_ is written twice. § VIII. UNITY [OR SIMILARITY] OF TYPE IN THE GREAT CLASSES. Nothing more wonderful in Nat. Hist. than looking at the vast number of organisms, recent and fossil, exposed to the most diverse conditions, living in the most distant climes, and at immensely remote periods, fitted to wholely different ends, yet to find large groups united by a similar type of structure. When we for instance see bat, horse, porpoise-fin, hand, all built on same structure{145}, having bones{146} with same name, we see there is some deep bond of union between them{147}, to illustrate this is the foundation and objects <?> <of> what is called the Natural System; and which is foundation of distinction <?> of true and adaptive characters{148}. Now this wonderful fact of hand, hoof, wing, paddle and claw being the same, is at once explicable on the principle of some parent-forms, which might either be <illegible> or walking animals, becoming through infinite number of small selections adapted to various conditions. We know that proportion, size, shape of bones and their accompanying soft parts vary, and hence constant selection would alter, to almost any purpose <?> the framework of an organism, but yet would leave a general, even closest similarity in it. {145} Written between the lines occurs:--"extend to birds and other classes." {146} Written between the lines occurs:--"many bones merely represented." {147} In the _Origin_, Ed. i. p. 434, vi. p. 595, the term _morphology_ is taken as including _unity of type_. The paddle of the porpoise and the wing of the bat are there used as instances of morphological resemblance. {148} The sentence is difficult to decipher. [We know the number of similar parts, as vertebræ and ribs can vary, hence this also we might expect.] Also <if> the changes carried on to a certain point, doubtless type will be lost, and this is case with Plesiosaurus{149}. The unity of type in past and present ages of certain great divisions thus undoubtedly receives the simplest explanation. {149} In the _Origin_, Ed. i. p. 436, vi. p. 598, the author speaks of the "general pattern" being obscured in the paddles of "extinct gigantic sea-lizards." There is another class of allied and almost identical facts, admitted by the soberest physiologists, [from the study of a certain set of organs in a group of organisms] and refers <? referring> to a unity of type of different organs in the same individual, denominated the science of "Morphology." The <? this> discovered by beautiful and regular series, and in the case of plants from monstrous changes, that certain organs in an individual are other organs metamorphosed. Thus every botanist considers petals, nectaries, stamens, pistils, germen as metamorphosed leaf. They thus explain, in the most lucid manner, the position and number of all parts of the flower, and the curious conversion under cultivation of one part into another. The complicated double set of jaws and palpi of crustaceans{150}, and all insects are considered as metamorphosed <limbs> and to see the series is to admit this phraseology. The skulls of the vertebrates are undoubtedly composed of three metamorphosed vertebræ; thus we can understand the strange form of the separate bones which compose the casket holding man's brain. These{151} facts differ but slightly from those of last section, if with wing, paddle, hand and hoof, some common structure was yet visible, or could be made out by a series of occasional monstrous conversions, and if traces could be discovered of <the> whole having once existed as walking or swimming instruments, these organs would be said to be metamorphosed, as it is they are only said to exhibit a common type. {150} See _Origin_, Ed. i. p. 437, vi. p. 599. {151} The following passage seems to have been meant to precede the sentence beginning "These facts":--"It is evident, that when in each individual species, organs are metamorph. a unity of type extends." This distinction is not drawn by physiologists, and is only implied by some by their general manner of writing. These facts, though affecting every organic being on the face of the globe, which has existed, or does exist, can only be viewed by the Creationist as ultimate and inexplicable facts. But this unity of type through the individuals of a group, and this metamorphosis of the same organ into other organs, adapted to diverse use, necessarily follows on the theory of descent{152}. For let us take case of Vertebrata, which if{153} they descended from one parent and by this theory all the Vertebrata have been altered by slow degrees, such as we see in domestic animals. We know that proportions alter, and even that occasionally numbers of vertebræ alter, that parts become soldered, that parts are lost, as tail and toes, but we know <that?> here we can see that possibly a walking organ might <?> be converted into swimming or into a gliding organ and so on to a flying organ. But such gradual changes would not alter the unity of type in their descendants, as parts lost and soldered and vertebræ. But we can see that if this carried to extreme, unity lost,--Plesiosaurus. Here we have seen the same organ is formed <?> <for> different purposes <ten words illegible>: and if, in several orders of vertebrata, we could trace origin <of> spinous processes and monstrosities &c. we should say, instead of there existing a unity of type, morphology{154}, as we do when we trace the head as being the vertebræ metamorphosed. Be it observed that Naturalists, as they use terms of affinity without attaching real meaning, here also they are obliged to use metamorphosis, without meaning that any parent of crustacean was really an animal with as many legs as crustacean has jaws. The theory of descent at once explains these wonderful facts. {152} This is, I believe, the first place in which the author uses the words "theory of descent." {153} The sentence should probably run, "Let us take the case of the vertebrata: if we assume them to be descended from one parent, then by this theory they have been altered &c." {154} That is "we should call it a morphological fact." Now few of the physiologists who use this language really suppose that the parent of insect with the metamorphosed jaw, was an insect with [more] so many legs, or that the parent of flowering plants, originally had no stamens, or pistils or petals, but some other means of propagation,--and so in other cases. Now according to our theory during the infinite number of changes, we might expect that an organ used for a purpose might be used for a different one by his descendant, as must have been the case by our theory with the bat, porpoise, horse, &c., which are descended from one parent. And if it so chanced that traces of the former use and structure of the part should be retained, which is manifestly possible if not probable, then we should have the organs, on which morphology is founded and which instead of being metaphorical becomes plain and <and instead of being> utterly unintelligible becomes simple matter of fact{155}. {155} In the _Origin_, Ed. i. p. 438, vi. p. 602, the author, referring to the expressions used by naturalists in regard to morphology and metamorphosis, says "On my view these terms may be used literally." <_Embryology._> This general unity of type in great groups of organisms (including of course these morphological cases) displays itself in a most striking manner in the stages through which the foetus passes{156}. In early stage, the wing of bat, hoof, hand, paddle are not to be distinguished. At a still earlier <stage> there is no difference between fish, bird, &c. &c. and mammal. It is not that they cannot be distinguished, but the arteries{157} <illegible>. It is not true that one passes through the form of a lower group, though no doubt fish more nearly related to foetal state{158}. {156} See _Origin_, Ed. i. p. 439, vi. p. 605. {157} In the _Origin_, Ed. i. p. 440, vi. p. 606, the author argues that the "loop-like course of the arteries" in the vertebrate embryo has no direct relation to the conditions of existence. {158} The following passages are written across the page:--"They pass through the same phases, but some, generally called the higher groups, are further metamorphosed. ? Degradation and complication? no tendency to perfection. ? Justly argued against Lamarck?" This similarity at the earliest stage is remarkably shown in the course of the arteries which become greatly altered, as foetus advances in life and assumes the widely different course and number which characterize full-grown fish and mammals. How wonderful that in egg, in water or air, or in womb of mother, artery{159} should run in same course. {159} An almost identical passage occurs in the _Origin_, Ed. i. p. 440, vi. p. 606. Light can be thrown on this by our theory. The structure of each organism is chiefly adapted to the sustension of its life, when full-grown, when it has to feed itself and propagate{160}. The structure of a kitten is quite in secondary degree adapted to its habits, whilst fed by its mother's milk and prey. Hence variation in the structure of the full-grown species will _chiefly_ determine the preservation of a species now become ill-suited to its habitat, or rather with a better place opened to it in the economy of Nature. It would not matter to the full-grown cat whether in its young state it was more or less eminently feline, so that it become so when full-grown. No doubt most variation, (not depending on habits of life of individual) depends on early change{161} and we must suspect that at whatever time of life the alteration of foetus is effected, it tends to appear at same period. When we <see> a tendency to particular disease in old age transmitted by the male, we know some effect is produced during conception, on the simple cell of ovule, which will not produce its effect till half a century afterwards and that effect is not visible{162}. So we see in grey-hound, bull-dog, in race-horse and cart-horse, which have been selected for their form in full-life, there is much less (?) difference in the few first days after birth{163}, than when full-grown: so in cattle, we see it clearly in cases of cattle, which differ obviously in shape and length of horns. If man were during 10,000 years to be able to select, far more diverse animals from horse or cow, I should expect there would be far less differences in the very young and foetal state: and this, I think, throws light on above marvellous fact. In larvæ, which have long life selection, perhaps, does much,--in the pupa not so much{164} There is no object gained in varying form &c. of foetus (beyond certain adaptations to mother's womb) and therefore selection will not further act on it, than in giving to its changing tissues a tendency to certain parts afterwards to assume certain forms. {160} The following: "Deaths of brothers <when> old by same peculiar disease" which is written between the lines seems to have been a memorandum which is expanded a few lines lower. I believe the case of the brothers came from Dr R. W. Darwin. {161} See the discussion to this effect in the _Origin_, Ed. i. pp. 443-4, vi. p. 610. The author there makes the distinction between a cause affecting the germ-cell and the reaction occurring at a late period of life. {162} Possibly the sentence was meant to end "is not visible till then." {163} See _Origin_, Ed. i. pp. 444-5, vi. p. 611. The query appended to _much less_ is justified, since measurement was necessary to prove that the greyhound and bulldog puppies had not nearly acquired "their full amount of proportional difference." {164} <The following discussion, from the back of the page, is in large measure the same as the text.> I think light can be thrown on these facts. From the following peculiarities being hereditary, [we know that some change in the germinal vesicle is effected, which will only betray itself years after] diseases--man, goitre, gout, baldness, fatness, size, [longevity <illegible> time of reproduction, shape of horns, case of old brothers dying of same disease]. And we know that the germinal vesicle must have been affected, though no effect is apparent or can be apparent till years afterwards,--no more apparent than when these peculiarities appear by the exposure of the full-grown individual. <That is, "the young individual is as apparently free from the hereditary changes which will appear later, as the young is actually free from the changes produced by exposure to certain conditions in adult life."> So that when we see a variety in cattle, even if the variety be due to act of reproduction, we cannot feel sure at what period this change became apparent. It may have been effected during early age of free life <or> foetal existence, as monsters show. From arguments before used, and crossing, we may generally suspect in germ; but I repeat it does not follow, that the change should be apparent till life fully developed; any more than fatness depending on heredity should be apparent during early childhood, still less during foetal existence. In case of horns of cattle, which when inherited must depend on germinal vesicle, obviously no effect till cattle full-grown. Practically it would appear that the [hereditary] peculiarities characterising our domestic races, therefore resulting from vesicle, do not appear with their full characters in very early states; thus though two breeds of cows have calves different, they are not so different,--grey-hound and bull-dog. And this is what is <to> be expected, for man is indifferent to characters of young animals and hence would select those full-grown animals which possessed the desirable characteristics. So that from mere chance we might expect that some of the characters would be such only as became fully apparent in mature life. Furthermore we may suspect it to be a law, that at whatever time a new character appears, whether from vesicle, or effects of external conditions, it would appear at corresponding time <see _Origin_, Ed. i. p. 444>. Thus diseases appearing in old age produce children with d^o.,--early maturity,--longevity,--old men, brothers, of same disease--young children of d^o. I said men do not select for quality of young,--calf with big bullocks. Silk-worms, peculiarities which, appear in caterpillar state or cocoon state, are transmitted to corresponding states. The effect of this would be that if some peculiarity was born in a young animal, but never exercised, it might be inherited in young animal; but if exercised that part of structure would be increased and would be inherited in corresponding time of life after such training. I have said that man selects in full-life, so would it be in Nature. In struggle of existence, it matters nothing to a feline animal, whether kitten eminently feline, as long as it sucks. Therefore natural selection would act equally well on character which was fully <developed> only in full age. Selection could tend to alter no character in foetus, (except relation to mother) it would alter less in young state (putting on one side larva condition) but alter every part in full-grown condition. Look to a foetus and its parent, and again after ages foetus and its <i. e. the above mentioned parents> descendant; the parent more variable <?> than foetus, which explains all.] Thus there is no power to change the course of the arteries, as long as they nourish the foetus; it is the selection of slight changes which supervene at any time during <illegible> of life. The less differences of foetus,--this has obvious meaning on this view: otherwise how strange that a [monkey] horse, a man, a bat should at one time of life have arteries, running in a manner, which is only intelligibly useful in a fish! The natural system being on theory genealogical, we can at once see, why foetus, retaining traces of the ancestral form, is of the highest value in classification. § IX. <ABORTIVE ORGANS.> There is another grand class of facts relating to what are called abortive organs. These consist of organs which the same reasoning power that shows us how beautifully these organs in some cases are adapted to certain end, declares in other cases are absolutely useless. Thus teeth in Rhinoceros{165}, whale, narwhal,--bone on tibia, muscles which do not move,--little bone of wing of Apteryx,--bone representing extremities in some snake,--little wings within <?> soldered cover of beetles,--men and bulls, mammæ: filaments without anthers in plants, mere scales representing petals in others, in feather-hyacinth whole flower. Almost infinitely numerous. No one can reflect on these without astonishment, can anything be clearer than that wings are to fly and teeth <to bite>, and yet we find these organs perfect in every detail in situations where they cannot possibly be of their normal use{166}. {165} Some of these examples occur in _Origin_, Ed. i. pp. 450-51, vi. pp. 619-20. {166} The two following sentences are written, one down the margin, the other across the page. "Abortive organs eminently useful in classification. Embryonic state of organs. Rudiments of organs." The term abortive organ has been thus applied to above structure (as _invariable_ as all other parts{167}) from their absolute similarity to monstrous cases, where from _accident_, certain organs are not developed; as infant without arms or fingers with mere stump representing them: teeth represented by mere points of ossification: headless children with mere button,--viscera represented by small amorphous masses, &c.,--the tail by mere stump,--a solid horn by minute hanging one{168}. There is a tendency in all these cases, when life is preserved, for such structures to become hereditary. We see it in tailless dogs and cats. In plants we see this strikingly,--in Thyme, in _Linum flavum_,--stamen in _Geranium pyrenaicum_{169}. Nectaries abort into petals in Columbine <_Aquilegia_>, produced from some accident and then become hereditary, in some cases only when propagated by buds, in other cases by seed. These cases have been produced suddenly by accident in early growth, but it is part of law of growth that when any organ is not used it tends to diminish (duck's wing{170}?) muscles of dog's ears, <and of> rabbits, muscles wither, arteries grow up. When eye born defective, optic nerve (Tuco Tuco) is atrophied. As every part whether useful or not (diseases, double flowers) tends to be transmitted to offspring, the origin of abortive organs whether produced at the birth or slowly acquired is easily understood in domestic races of organisms: [a struggle between the atrophy and hereditariness. Abortive organs in domestic races.] There will always be a struggle between atrophy of an organ rendered useless, and hereditariness{171}. Because we can understand the origin of abortive organs in certain cases, it would be wrong to conclude absolutely that all must have had same origin, but the strongest analogy is in favour of it. And we can by our theory, for during infinite changes some organ, we might have anticipated, would have become useless. <We can> readily explain the fact, so astounding on any other view, namely that organs possibly useless have been formed often with the same exquisite care as when of vital importance. {167} I imagine the meaning to be that abortive organs are specific characters in contrast to monstrosities. {168} Minute hanging horns are mentioned in the _Origin_, Ed. i. p. 454, vi. p. 625, as occurring in hornless breeds of cattle. {169} _Linum flavum_ is dimorphic: thyme gynodiæcious. It is not clear what point is referred to under _Geranium pyrenaicum_. {170} The author's work on duck's wings &c. is in _Var. under Dom._, Ed. 2, i. p. 299. {171} The words _vis medicatrix_ are inserted after "useless," apparently as a memorandum. Our theory, I may remark would permit an organ <to> become abortive with respect to its primary use, to be turned to any other purpose, (as the buds in a cauliflower) thus we can see no difficulty in bones of male marsupials being used as fulcrum of muscles, or style of marygold{172},--indeed in one point of view, the heads of [vertebrated] animal may be said to be abortive vertebræ turned into other use: legs of some crustacea abortive jaws, &c., &c. De Candolle's analogy of table covered with dishes{173}. {172} In the male florets of certain Compositæ the style functions merely as a piston for forcing out the pollen. {173} <On the back of the page is the following.> If abortive organs are a trace preserved by hereditary tendency, of organ in ancestor of use, we can at once see why important in natural classification, also why more plain in young animal because, as in last section, the selection has altered the old animal most. I repeat, these wondrous facts, of parts created for no use in past and present time, all can by my theory receive simple explanation; or they receive none and we must be content with some such empty metaphor, as that of De Candolle, who compares creation to a well covered table, and says abortive organs may be compared to the dishes (some should be empty) placed symmetrically! <The following passage was possibly intended to be inserted here.> Degradation and complication see Lamarck: no tendency to perfection: if room, [even] high organism would have greater power in beating lower one, thought <?> to be selected for a degraded end. § X. RECAPITULATION AND CONCLUSION. Let us recapitulate the whole <?> <of> these latter sections by taking case of the three species of Rhinoceros, which inhabit Java, Sumatra, and mainland of Malacca or India. We find these three close neighbours, occupants of distinct but neighbouring districts, as a group having a different aspect from the Rhinoceros of Africa, though some of these latter inhabit very similar countries, but others most diverse stations. We find them intimately related [scarcely <?> differences more than some breeds of cattle] in structure to the Rhinoceros, which for immense periods have inhabited this one, out of three main zoological divisions of the world. Yet some of these ancient animals were fitted to very different stations: we find all three <illegible> of the generic character of the Rhinoceros, which form a [piece of net]{174} set of links in the broken chain representing the Pachydermata, as the chain likewise forms a portion in other and longer chains. We see this wonderfully in dissecting the coarse leg of all three and finding nearly the same bones as in bat's wings or man's hand, but we see the clear mark in solid tibia of the fusion into it of the fibula. In all three we find their heads composed of three altered vertebræ, short neck, same bones as giraffe. In the upper jaws of all three we find small teeth like rabbit's. In dissecting them in foetal state we find at a not very early stage their form exactly alike the most different animals, and even with arteries running as in a fish: and this similarity holds when the young one is produced in womb, pond, egg or spawn. Now these three undoubted species scarcely differ more than breeds of cattle, are probably subject to many the same contagious diseases; if domesticated these forms would vary, and they might possibly breed together, and fuse into something{175} different <from> their aboriginal forms; might be selected to serve different ends. {174} The author doubtless meant that the complex relationships between organisms can be roughly represented by a net in which the knots stand for species. {175} Between the lines occurs:--"one <?> form be lost." Now the Creationist believes these three Rhinoceroses were created{176} with their deceptive appearance of true, not <illegible> relationship; as well can I believe the planets revolve in their present courses not from one law of gravity but from distinct volition of Creator. {176} The original sentence is here broken up by the insertion of:--"out of the dust of Java, Sumatra, these <?> allied to past and present age and <illegible>, with the stamp of inutility in some of their organs and conversion in others." If real species, sterile one with another, differently adapted, now inhabiting different countries, with different structures and instincts, are admitted to have common descent, we can only legitimately stop where our facts stop. Look how far in some case a chain of species will lead us. <This probably refers to the Crustacea, where the two ends of the series have "hardly a character in common." _Origin_, Ed. i. p. 419.> May we not jump (considering how much extermination, and how imperfect geological records) from one sub-genus to another sub-genus. Can genera restrain us; many of the same arguments, which made us give up species, inexorably demand genera and families and orders to fall, and classes tottering. We ought to stop only when clear unity of type, independent of use and adaptation, ceases. Be it remembered no naturalist pretends to give test from external characters of species; in many genera the distinction is quite arbitrary{177}. But there remains one other way of comparing species with races; it is to compare the effects of crossing them. Would it not be wonderful, if the union of two organisms, produced by two separate acts of Creation, blended their characters together when crossed according to the same rules, as two races which have undoubtedly descended from same parent stock; yet this can be shown to be the case. For sterility, though a usual <?>, is not an invariable concomitant, it varies much in degree and has been shown to be probably dependent on causes closely analogous with those which make domesticated organisms sterile. Independent of sterility there is no difference between mongrels and hybrids, as can be shown in a long series of facts. It is strikingly seen in cases of instincts, when the minds of the two species or races become blended together{178}. In both cases if the half-breed be crossed with either parent for a few generations, all traces of the one parent form is lost (as Kölreuter in two tobacco species almost sterile together), so that the Creationist in the case of a species, must believe that one act of creation is absorbed into another! {177} Between the lines occur the words:--"Species vary according to same general laws as varieties; they cross according to same laws." {178} "A cross with a bull-dog has affected for many generations the courage and obstinacy of greyhounds," _Origin_, Ed. i. p. 214, vi. p. 327. {Illustration: Facsimile of the original manuscript of the paragraph on p. 50.} CONCLUSION. Such are my reasons for believing that specific forms are not immutable. The affinity of different groups, the unity of types of structure, the representative forms through which foetus passes, the metamorphosis of organs, the abortion of others cease to be metaphorical expressions and become intelligible facts. We no longer look <an> on animal as a savage does at a ship{179}, or other great work of art, as a thing wholly beyond comprehension, but we feel far more interest in examining it. How interesting is every instinct, when we speculate on their origin as an hereditary or congenital habit or produced by the selection of individuals differing slightly from their parents. We must look at every complicated mechanism and instinct, as the summary of a long history, <as the summing up> of{180} useful contrivances, much like a work of art. How interesting does the distribution of all animals become, as throwing light on ancient geography. [We see some seas bridged over.] Geology loses in its glory from the imperfection of its archives{181}, but how does it gain in the immensity of the periods of its formations and of the gaps separating these formations. There is much grandeur in looking at the existing animals either as the lineal descendants of the forms buried under thousand feet of matter, or as the coheirs of some still more ancient ancestor. It accords with what we know of the law impressed on matter by the Creator, that the creation and extinction of forms, like the birth and death of individuals should be the effect of secondary [laws] means{182}. It is derogatory that the Creator of countless systems of worlds should have created each of the myriads of creeping parasites and [slimy] worms which have swarmed each day of life on land and water <on> [this] one globe. We cease being astonished, however much we may deplore, that a group of animals should have been directly created to lay their eggs in bowels and flesh of other,--that some organisms should delight in cruelty,--that animals should be led away by false instincts,--that annually there should be an incalculable waste of eggs and pollen. From death, famine, rapine, and the concealed war of nature we can see that the highest good, which we can conceive, the creation of the higher animals has directly come. Doubtless it at first transcends our humble powers, to conceive laws capable of creating individual organisms, each characterised by the most exquisite workmanship and widely-extended adaptations. It accords better with [our modesty] the lowness of our faculties to suppose each must require the fiat of a creator, but in the same proportion the existence of such laws should exalt our notion of the power of the omniscient Creator{183}. There is a simple grandeur in the view of life with its powers of growth, assimilation and reproduction, being originally breathed into matter under one or a few forms, and that whilst this our planet has gone circling on according to fixed laws, and land and water, in a cycle of change, have gone on replacing each other, that from so simple an origin, through the process of gradual selection of infinitesimal changes, endless forms most beautiful and most wonderful have been evolved{184}. {179} The simile of the savage and the ship occurs in the _Origin_, Ed. i. p. 485, vi. p. 665. {180} In the _Origin_, Ed. i. p. 486, vi. p. 665, the author speaks of the "summing up of many contrivances": I have therefore introduced the above words which make the passage clearer. In the _Origin_ the comparison is with "a great mechanical invention,"--not with a work of art. {181} See a similar passage in the _Origin_, Ed. i. p. 487, vi. p. 667. {182} See the _Origin_, Ed. i. p. 488, vi. p. 668. {183} The following discussion, together with some memoranda are on the last page of the MS. "The supposed creative spirit does not create either number or kind which <are> from analogy adapted to site (viz. New Zealand): it does not keep them all permanently adapted to any country,--it works on spots or areas of creation,--it is not persistent for great periods,--it creates forms of same groups in same regions, with no physical similarity,--it creates, on islands or mountain summits, species allied to the neighbouring ones, and not allied to alpine nature as shown in other mountain summits--even different on different island of similarly constituted archipelago, not created on two points: never mammifers created on small isolated island; nor number of organisms adapted to locality: its power seems influenced or related to the range of other species wholly distinct of the same genus,--it does not equally effect, in amount of difference, all the groups of the same class." {184} This passage is the ancestor of the concluding words in the first edition of the _Origin of Species_ which have remained substantially unchanged throughout subsequent editions, "There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved." In the 2nd edition "by the Creator" is introduced after "originally breathed." N.B.--There ought somewhere to be a discussion from Lyell to show that external conditions do vary, or a note to Lyell's works <work?>. Besides other difficulties in ii. Part, non-acclimatisation of plants. Difficulty when asked _how_ did white and negro become altered from common intermediate stock: no facts. We do NOT know that species are immutable, on the contrary. What arguments against this theory, except our not perceiving every step, like the erosion of valleys{185}. {185} Compare the _Origin_, Ed. i. p. 481, vi. p. 659, "The difficulty is the same as that felt by so many geologists, when Lyell first insisted that long lines of inland cliffs had been formed, and great valleys excavated, by the slow action of the coast-waves." THE ESSAY OF 1844 PART I CHAPTER I ON THE VARIATION OF ORGANIC BEINGS UNDER DOMESTICATION; AND ON THE PRINCIPLES OF SELECTION The most favourable conditions for variation seem to be when organic beings are bred for many generations under domestication{186}: one may infer this from the simple fact of the vast number of races and breeds of almost every plant and animal, which has long been domesticated. Under certain conditions organic beings even during their individual lives become slightly altered from their usual form, size, or other characters: and many of the peculiarities thus acquired are transmitted to their offspring. Thus in animals, the size and vigour of body, fatness, period of maturity, habits of body or consensual movements, habits of mind and temper, are modified or acquired during the life of the individual{187}, and become inherited. There is reason to believe that when long exercise has given to certain muscles great development, or disuse has lessened them, that such development is also inherited. Food and climate will occasionally produce changes in the colour and texture of the external coverings of animals; and certain unknown conditions affect the horns of cattle in parts of Abyssinia; but whether these peculiarities, thus acquired during individual lives, have been inherited, I do not know. It appears certain that malconformation and lameness in horses, produced by too much work on hard roads,--that affections of the eyes in this animal probably caused by bad ventilation,--that tendencies towards many diseases in man, such as gout, caused by the course of life and ultimately producing changes of structure, and that many other diseases produced by unknown agencies, such as goitre, and the idiotcy resulting from it, all become hereditary. {186} The cumulative effect of domestication is insisted on in the _Origin_, see _e.g. Origin_, Ed. i. p. 7, vi. p. 8. {187} This type of variation passes into what he describes as the direct effect of conditions. Since they are due to causes acting during the adult life of the organism they might be called individual variations, but he uses this term for congenital variations, _e.g._ the differences discoverable in plants raised from seeds of the same pod _(Origin_, Ed. i. p. 45, vi. p. 53). It is very doubtful whether the flowers and leaf-buds, annually produced from the same bulb, root, or tree, can properly be considered as parts of the same individual, though in some respects they certainly seem to be so. If they are parts of an individual, plants also are subject to considerable changes during their _individual_ lives. Most florist-flowers if neglected degenerate, that is, they lose some of their characters; so common is this, that trueness is often stated, as greatly enhancing the value of a variety{188}: tulips break their colours only after some years' culture; some plants become double and others single, by neglect or care: these characters can be transmitted by cuttings or grafts, and in some cases by true or seminal propagation. Occasionally a single bud on a plant assumes at once a new and widely different character: thus it is certain that nectarines have been produced on peach trees and moss roses on provence roses; white currants on red currant bushes; flowers of a different colour from that of the stock, in Chrysanthemums, Dahlias, sweet-williams, Azaleas, &c., &c.; variegated leaf-buds on many trees, and other similar cases. These new characters appearing in single buds, can, like those lesser changes affecting the whole plant, be multiplied not only by cuttings and such means, but often likewise by true seminal generation. {188} <It is not clear where the following note is meant to come>: Case of Orchis,--most remarkable as not long cultivated by seminal propagation. Case of varieties which soon acquire, like _Ægilops_ and Carrot (and Maize) _a certain general character_ and then go on varying. The changes thus appearing during the lives of individual animals and plants are extremely rare compared with those which are congenital or which appear soon after birth. Slight differences thus arising are infinitely numerous: the proportions and form of every part of the frame, inside and outside, appear to vary in very slight degrees: anatomists dispute what is the "beau ideal" of the bones, the liver and kidneys, like painters do of the proportions of the face: the proverbial expression that no two animals or plants are born absolutely alike, is much truer when applied to those under domestication, than to those in a state of nature{189}. Besides these slight differences, single individuals are occasionally born considerably unlike in certain parts or in their whole structure to their parents: these are called by horticulturists and breeders "sports"; and are not uncommon except when very strongly marked. Such sports are known in some cases to have been parents of some of our domestic races; and such probably have been the parents of many other races, especially of those which in some senses may be called hereditary monsters; for instance where there is an additional limb, or where all the limbs are stunted (as in the Ancon sheep), or where a part is wanting, as in rumpless fowls and tailless dogs or cats{190}. The effects of external conditions on the size, colour and form, which can rarely and obscurely be detected during one individual life, become apparent after several generations: the slight differences, often hardly describable, which characterize the stock of different countries, and even of districts in the same country, seem to be due to such continued action. {189} Here, as in the MS. of 1842, the author is inclined to minimise the variation occurring in nature. {190} This is more strongly stated than in the _Origin_, Ed. i. p. 30. _On the hereditary tendency._ A volume might be filled with facts showing what a strong tendency there is to inheritance, in almost every case of the most trifling, as well as of the most remarkable congenital peculiarities{191}. The term congenital peculiarity, I may remark, is a loose expression and can only mean a peculiarity apparent when the part affected is nearly or fully developed: in the Second Part, I shall have to discuss at what period of the embryonic life connatal peculiarities probably first appear; and I shall then be able to show from some evidence, that at whatever period of life a new peculiarity first appears, it tends hereditarily to appear at a corresponding period{192}. Numerous though slight changes, slowly supervening in animals during mature life (often, though by no means always, taking the form of disease), are, as stated in the first paragraphs, very often hereditary. In plants, again, the buds which assume a different character from their stock likewise tend to transmit their new peculiarities. There is not sufficient reason to believe that either mutilations{193} or changes of form produced by mechanical pressure, even if continued for hundreds of generations, or that any changes of structure quickly produced by disease, are inherited; it would appear as if the tissue of the part affected must slowly and freely grow into the new form, in order to be inheritable. There is a very great difference in the hereditary tendency of different peculiarities, and of the same peculiarity, in different individuals and species; thus twenty thousand seeds of the weeping ash have been sown and not one come up true;--out of seventeen seeds of the weeping yew, nearly all came up true. The ill-formed and almost monstrous "Niata" cattle of S. America and Ancon sheep, both when bred together and when crossed with other breeds, seem to transmit their peculiarities to their offspring as truly as the ordinary breeds. I can throw no light on these differences in the power of hereditary transmission. Breeders believe, and apparently with good cause, that a peculiarity generally becomes more firmly implanted after having passed through several generations; that is if one offspring out of twenty inherits a peculiarity from its parents, then its descendants will tend to transmit this peculiarity to a larger proportion than one in twenty; and so on in succeeding generations. I have said nothing about mental peculiarities being inheritable for I reserve this subject for a separate chapter. {191} See _Origin_, Ed. i. p. 13. {192} _Origin_, Ed. i. p. 86, vi. p. 105. {193} It is interesting to find that though the author, like his contemporaries, believed in the inheritance of acquired characters, he excluded the case of mutilation. _Causes of Variation._ Attention must here be drawn to an important distinction in the first origin or appearance of varieties: when we see an animal highly kept producing offspring with an hereditary tendency to early maturity and fatness; when we see the wild-duck and Australian dog always becoming, when bred for one or a few generations in confinement, mottled in their colours; when we see people living in certain districts or circumstances becoming subject to an hereditary taint to certain organic diseases, as consumption or plica polonica,--we naturally attribute such changes to the direct effect of known or unknown agencies acting for one or more generations on the parents. It is probable that a multitude of peculiarities may be thus directly caused by unknown external agencies. But in breeds, characterized by an extra limb or claw, as in certain fowls and dogs; by an extra joint in the vertebræ; by the loss of a part, as the tail; by the substitution of a tuft of feathers for a comb in certain poultry; and in a multitude of other cases, we can hardly attribute these peculiarities directly to external influences, but indirectly to the laws of embryonic growth and of reproduction. When we see a multitude of varieties (as has often been the case, where a cross has been carefully guarded against) produced from seeds matured in the very same capsule{194}, with the male and female principle nourished from the same roots and necessarily exposed to the same external influences; we cannot believe that the endless slight differences between seedling varieties thus produced, can be the effect of any corresponding difference in their exposure. We are led (as Müller has remarked) to the same conclusion, when we see in the same litter, produced by the same act of conception, animals considerably different. {194} This corresponds to _Origin_, Ed. i. p. 10, vi. p. 9. As variation to the degree here alluded to has been observed only in organic beings under domestication, and in plants amongst those most highly and long cultivated, we must attribute, in such cases, the varieties (although the difference between each variety cannot possibly be attributed to any corresponding difference of exposure in the parents) to the indirect effects of domestication on the action of the reproductive system{195}. It would appear as if the reproductive powers failed in their ordinary function of producing new organic beings closely like their parents; and as if the entire organization of the embryo, under domestication, became in a slight degree plastic{196}. We shall hereafter have occasion to show, that in organic beings, a considerable change from the natural conditions of life, affects, independently of their general state of health, in another and remarkable manner the reproductive system. I may add, judging from the vast number of new varieties of plants which have been produced in the same districts and under nearly the same routine of culture, that probably the indirect effects of domestication in making the organization plastic, is a much more efficient source of variation than any direct effect which external causes may have on the colour, texture, or form of each part. In the few instances in which, as in the Dahlia{197}, the course of variation has been recorded, it appears that domestication produces little effect for several generations in rendering the organization plastic; but afterwards, as if by an accumulated effect, the original character of the species suddenly gives way or breaks. {195} _Origin_, Ed. i. p. 8, vi. p. 10. {196} For _plasticity_ see _Origin_, Ed. i. pp. 12, 132. {197} _Var. under Dom._, Ed. ii. I. p. 393. _On Selection._ We have hitherto only referred to the first appearance in individuals of new peculiarities; but to make a race or breed, something more is generally{198} requisite than such peculiarities (except in the case of the peculiarities being the direct effect of constantly surrounding conditions) should be inheritable,--namely the principle of selection, implying separation. Even in the rare instances of sports, with the hereditary tendency very strongly implanted, crossing must be prevented with other breeds, or if not prevented the best characterized of the half-bred offspring must be carefully selected. Where the external conditions are constantly tending to give some character, a race possessing this character will be formed with far greater ease by selecting and breeding together the individuals most affected. In the case of the endless slight variations produced by the indirect effects of domestication on the action of the reproductive system, selection is indispensable to form races; and when carefully applied, wonderfully numerous and diverse races can be formed. Selection, though so simple in theory, is and has been important to a degree which can hardly be overrated. It requires extreme skill, the results of long practice, in detecting the slightest difference in the forms of animals, and it implies some distinct object in view; with these requisites and patience, the breeder has simply to watch for every the smallest approach to the desired end, to select such individuals and pair them with the most suitable forms, and so continue with succeeding generations. In most cases careful selection and the prevention of accidental crosses will be necessary for several generations, for in new breeds there is a strong tendency to vary and especially to revert to ancestral forms: but in every succeeding generation less care will be requisite for the breed will become truer; until ultimately only an occasional individual will require to be separated or destroyed. Horticulturalists in raising seeds regularly practise this, and call it "roguing," or destroying the "rogues" or false varieties. There is another and less efficient means of selection amongst animals: namely repeatedly procuring males with some desirable qualities, and allowing them and their offspring to breed freely together; and this in the course of time will affect the whole lot. These principles of selection have been _methodically_ followed for scarcely a century; but their high importance is shown by the practical results, and is admitted in the writings of the most celebrated agriculturalists and horticulturalists;--I need only name Anderson, Marshall, Bakewell, Coke, Western, Sebright and Knight. {198} Selection is here used in the sense of isolation, rather than as implying the summation of small differences. Professor Henslow in his _Heredity of Acquired Characters in Plants_, 1908, p. 2, quotes from Darwin's _Var. under Dom._, Ed. i. II. p. 271, a passage in which the author, speaking of the direct action of conditions, says:--"A new sub-variety would thus be produced without the aid of selection." Darwin certainly did not mean to imply that such varieties are freed from the action of natural selection, but merely that a new form may appear without _summation_ of new characters. Professor Henslow is apparently unaware that the above passage is omitted in the second edition of _Var. under Dom._, II. p. 260. Even in well-established breeds the individuals of which to an unpractised eye would appear absolutely similar, which would give, it might have been thought, no scope to selection, the whole appearance of the animal has been changed in a few years (as in the case of Lord Western's sheep), so that practised agriculturalists could scarcely credit that a change had not been effected by a cross with other breeds. Breeders both of plants and animals frequently give their means of selection greater scope, by crossing different breeds and selecting the offspring; but we shall have to recur to this subject again. The external conditions will doubtless influence and modify the results of the most careful selection; it has been found impossible to prevent certain breeds of cattle from degenerating on mountain pastures; it would probably be impossible to keep the plumage of the wild-duck in the domesticated race; in certain soils, no care has been sufficient to raise cauliflower seed true to its character; and so in many other cases. But with patience it is wonderful what man has effected. He has selected and therefore in one sense made one breed of horses to race and another to pull; he has made sheep with fleeces good for carpets and other sheep good for broadcloth; he has, in the same sense, made one dog to find game and give him notice when found, and another dog to fetch him the game when killed; he has made by selection the fat to lie mixed with the meat in one breed and in another to accumulate in the bowels for the tallow-chandler{199}; he has made the legs of one breed of pigeons long, and the beak of another so short, that it can hardly feed itself; he has previously determined how the feathers on a bird's body shall be coloured, and how the petals of many flowers shall be streaked or fringed, and has given prizes for complete success;--by selection, he has made the leaves of one variety and the flower-buds of another variety of the cabbage good to eat, at different seasons of the year; and thus has he acted on endless varieties. I do not wish to affirm that the long-and short-wooled sheep, or that the pointer and retriever, or that the cabbage and cauliflower have certainly descended from one and the same aboriginal wild stock; if they have not so descended, though it lessens what man has effected, a large result must be left unquestioned. {199} See the Essay of 1842, p. 3. In saying as I have done that man makes a breed, let it not be confounded with saying that man makes the individuals, which are given by nature with certain desirable qualities; man only adds together and makes a permanent gift of nature's bounties. In several cases, indeed, for instance in the "Ancon" sheep, valuable from not getting over fences, and in the turnspit dog, man has probably only prevented crossing; but in many cases we positively know that he has gone on selecting, and taking advantage of successive small variations. Selection{200} has been _methodically_ followed, as I have said, for barely a century; but it cannot be doubted that occasionally it has been practised from the remotest ages, in those animals completely under the dominion of man. In the earliest chapters of the Bible there are rules given for influencing the colours of breeds, and black and white sheep are spoken of as separated. In the time of Pliny the barbarians of Europe and Asia endeavoured by cross-breeding with a wild stock to improve the races of their dogs and horses. The savages of Guyana now do so with their dogs: such care shows at least that the characters of individual animals were attended to. In the rudest times of English history, there were laws to prevent the exportation of fine animals of established breeds, and in the case of horses, in Henry VIII's time, laws for the destruction of all horses under a certain size. In one of the oldest numbers of the _Phil. Transactions_, there are rules for selecting and improving the breeds of sheep. Sir H. Bunbury, in 1660, has given rules for selecting the finest seedling plants, with as much precision as the best recent horticulturalist could. Even in the most savage and rude nations, in the wars and famines which so frequently occur, the most useful of their animals would be preserved: the value set upon animals by savages is shown by the inhabitants of Tierra del Fuego devouring their old women before their dogs, which as they asserted are useful in otter-hunting{201}: who can doubt but that in every case of famine and war, the best otter-hunters would be preserved, and therefore in fact selected for breeding. As the offspring so obviously take after their parents, and as we have seen that savages take pains in crossing their dogs and horses with wild stocks, we may even conclude as probable that they would sometimes pair the most useful of their animals and keep their offspring separate. As different races of men require and admire different qualities in their domesticated animals, each would thus slowly, though unconsciously, be selecting a different breed. As Pallas has remarked, who can doubt but that the ancient Russian would esteem and endeavour to preserve those sheep in his flocks which had the thickest coats. This kind of insensible selection by which new breeds are not selected and kept separate, but a peculiar character is slowly given to the whole mass of the breed, by often saving the life of animals with certain characteristics, we may feel nearly sure, from what we see has been done by the more direct method of separate selection within the last 50 years in England, would in the course of some thousand years produce a marked effect. {200} See _Origin_, Ed. i. p. 33, vi. p. 38. The evidence is given in the present Essay rather more fully than in the _Origin_. {201} _Journal of Researches_, Ed. 1860, p. 214. "Doggies catch otters, old women no." _Crossing Breeds._ When once two or more races are formed, or if more than one race, or species fertile _inter se_, originally existed in a wild state, their crossing becomes a most copious source of new races{202}. When two well-marked races are crossed the offspring in the first generation take more or less after either parent or are quite intermediate between them, or rarely assume characters in some degree new. In the second and several succeeding generations, the offspring are generally found to vary exceedingly, one compared with another, and many revert nearly to their ancestral forms. This greater variability in succeeding generations seems analogous to the breaking or variability of organic beings after having been bred for some generations under domestication{203}. So marked is this variability in cross-bred descendants, that Pallas and some other naturalists have supposed that all variation is due to an original cross; but I conceive that the history of the potato, Dahlia, Scotch Rose, the guinea-pig, and of many trees in this country, where only one species of the genus exists, clearly shows that a species may vary where there can have been no crossing. Owing to this variability and tendency to reversion in cross-bred beings, much careful selection is requisite to make intermediate or new permanent races: nevertheless crossing has been a most powerful engine, especially with plants, where means of propagation exist by which the cross-bred varieties can be secured without incurring the risk of fresh variation from seminal propagation: with animals the most skilful agriculturalists now greatly prefer careful selection from a well-established breed, rather than from uncertain cross-bred stocks. {202} The effects of crossing is much more strongly stated here than in the _Origin_. See Ed. i. p. 20, vi. p. 23, where indeed the opposite point of view is given. His change of opinion may be due to his work on pigeons. The whole of the discussion on crossing corresponds to Chapter VIII of the _Origin_, Ed. i. rather than to anything in the earlier part of the book. {203} The parallelism between the effects of a cross and the effects of conditions is given from a different point of view in the _Origin_, Ed. i. p. 266, vi. p. 391. See the experimental evidence for this important principle in the author's work on _Cross and Self-Fertilisation_. Professor Bateson has suggested that the experiments should be repeated with gametically pure plants. Although intermediate and new races may be formed by the mingling of others, yet if the two races are allowed to mingle quite freely, so that none of either parent race remain pure, then, especially if the parent races are not widely different, they will slowly blend together, and the two races will be destroyed, and one mongrel race left in its place. This will of course happen in a shorter time, if one of the parent races exists in greater number than the other. We see the effect of this mingling, in the manner in which the aboriginal breeds of dogs and pigs in the Oceanic Islands and the many breeds of our domestic animals introduced into S. America, have all been lost and absorbed in a mongrel race. It is probably owing to the freedom of crossing, that, in uncivilised countries, where inclosures do not exist, we seldom meet with more than one race of a species: it is only in enclosed countries, where the inhabitants do not migrate, and have conveniences for separating the several kinds of domestic animals, that we meet with a multitude of races. Even in civilised countries, want of care for a few years has been found to destroy the good results of far longer periods of selection and separation. This power of crossing will affect the races of all _terrestrial_ animals; for all terrestrial animals require for their reproduction the union of two individuals. Amongst plants, races will not cross and blend together with so much freedom as in terrestrial animals; but this crossing takes place through various curious contrivances to a surprising extent. In fact such contrivances exist in so very many hermaphrodite flowers by which an occasional cross may take place, that I cannot avoid suspecting (with Mr Knight) that the reproductive action requires, at _intervals_, the concurrence of distinct individuals{204}. Most breeders of plants and animals are firmly convinced that benefit is derived from an occasional cross, not with another race, but with another family of the same race; and that, on the other hand, injurious consequences follow from long-continued close interbreeding in the same family. Of marine animals, many more, than was till lately believed, have their sexes on separate individuals; and where they are hermaphrodite, there seems very generally to be means through the water of one individual occasionally impregnating another: if individual animals can singly propagate themselves for perpetuity, it is unaccountable that no terrestrial animal, where the means of observation are more obvious, should be in this predicament of singly perpetuating its kind. I conclude, then, that races of most animals and plants, when unconfined in the same country, would tend to blend together. {204} The so-called Knight-Darwin Law is often misunderstood. See Goebel in _Darwin and Modern Science_, 1909, p. 419; also F. Darwin, _Nature_, Oct. 27, 1898. _Whether our domestic races have descended from one or more wild stocks._ Several naturalists, of whom Pallas{205} regarding animals, and Humboldt regarding certain plants, were the first, believe that the breeds of many of our domestic animals such as of the horse, pig, dog, sheep, pigeon, and poultry, and of our plants have descended from more than one aboriginal form. They leave it doubtful, whether such forms are to be considered wild races, or true species, whose offspring are fertile when crossed _inter se_. The main arguments for this view consist, firstly, of the great difference between such breeds, as the Race-and Cart-Horse, or the Greyhound and Bull-dog, and of our ignorance of the steps or stages through which these could have passed from a common parent; and secondly that in the most ancient historical periods, breeds resembling some of those at present most different, existed in different countries. The wolves of N. America and of Siberia are thought to be different species; and it has been remarked that the dogs belonging to the savages in these two countries resemble the wolves of the same country; and therefore that they have probably descended from two different wild stocks. In the same manner, these naturalists believe that the horse of Arabia and of Europe have probably descended from two wild stocks both apparently now extinct. I do not think the assumed fertility of these wild stocks any very great difficulty on this view; for although in animals the offspring of most cross-bred species are infertile, it is not always remembered that the experiment is very seldom fairly tried, except when two near species _both_ breed freely (which does not readily happen, as we shall hereafter see) when under the dominion of man. Moreover in the case of the China{206} and common goose, the canary and siskin, the hybrids breed freely; in other cases the offspring from hybrids crossed with either pure parent are fertile, as is practically taken advantage of with the yak and cow; as far as the analogy of plants serves, it is impossible to deny that some species are quite fertile _inter se_; but to this subject we shall recur. {205} Pallas' theory is discussed in the _Origin_, Ed. i. pp. 253, 254, vi. p. 374. {206} See Darwin's paper on the fertility of hybrids from the common and Chinese goose in _Nature_, Jan. 1, 1880. On the other hand, the upholders of the view that the several breeds of dogs, horses, &c., &c., have descended each from one stock, may aver that their view removes all _difficulty about fertility_, and that the main argument from the high antiquity of different breeds, somewhat similar to the present breeds, is worth little without knowing the date of the domestication of such animals, which is far from being the case. They may also with more weight aver that, knowing that organic beings under domestication do vary in some degree, the argument from the great difference between certain breeds is worth nothing, without we know the limits of variation during a long course of time, which is far from the case. They may argue that almost every county in England, and in many districts of other countries, for instance in India, there are slightly different breeds of the domestic animals; and that it is opposed to all that we know of the distribution of wild animals to suppose that these have descended from so many different wild races or species: if so, they may argue, is it not probable that countries quite separate and exposed to different climates would have breeds not slightly, but considerably, different? Taking the most favourable case, on both sides, namely that of the dog; they might urge that such breeds as the bull-dog and turnspit have been reared by man, from the ascertained fact that strictly analogous breeds (namely the Niata ox and Ancon sheep) in other quadrupeds have thus originated. Again they may say, seeing what training and careful selection has effected for the greyhound, and seeing how absolutely unfit the Italian greyhound is to maintain itself in a state of nature, is it not probable that at least all greyhounds,--from the rough deerhound, the smooth Persian, the common English, to the Italian,--have descended from one stock{207}? If so, is it so improbable that the deerhound and long-legged shepherd dog have so descended? If we admit this, and give up the bull-dog, we can hardly dispute the probable common descent of the other breeds. {207} _Origin_, Ed. i. p. 19, vi. p. 22. The evidence is so conjectural and balanced on both sides that at present I conceive that no one can decide: for my own part, I lean to the probability of most of our domestic animals having descended from more than one wild stock; though from the arguments last advanced and from reflecting on the slow though inevitable effect of different races of mankind, under different circumstances, saving the lives of and therefore selecting the individuals most useful to them, I cannot doubt but that one class of naturalists have much overrated the probable number of the aboriginal wild stocks. As far as we admit the difference of our races <to be> due to the differences of their original stocks, so much must we give up of the amount of variation produced under domestication. But this appears to me unimportant, for we certainly know in some few cases, for instance in the Dahlia, and potato, and rabbit, that a great number of varieties have proceeded from one stock; and, in many of our domestic races, we know that man, by slowly selecting and by taking advantage of sudden sports, has considerably modified old races and produced new ones. Whether we consider our races as the descendants of one or several wild stocks, we are in far the greater number of cases equally ignorant what these stocks were. _Limits to Variation in degree and kind._ Man's power in making races deends, in the first instance, on the stock on which he works being variable; but his labours are modified and limited, as we have seen, by the direct effects of the external conditions,--by the deficient or imperfect hereditariness of new peculiarities,--and by the tendency to continual variation and especially to reversion to ancestral forms. If the stock is not variable under domestication, of course he can do nothing; and it appears that species differ considerably in this tendency to variation, in the same way as even sub-varieties from the same variety differ greatly in this respect, and transmit to their offspring this difference in tendency. Whether the absence of a tendency to vary is an unalterable quality in certain species, or depends on some deficient condition of the particular state of domestication to which they are exposed, there is no evidence. When the organization is rendered variable, or plastic, as I have expressed it, under domestication, different parts of the frame vary more or less in different species: thus in the breeds of cattle it has been remarked that the horns are the most constant or least variable character, for these often remain constant, whilst the colour, size, proportions of the body, tendency to fatten &c., vary; in sheep, I believe, the horns are much more variable. As a general rule the less important parts of the organization seem to vary most, but I think there is sufficient evidence that every part occasionally varies in a slight degree. Even when man has the primary requisite variability he is necessarily checked by the health and life of the stock he is working on: thus he has already made pigeons with such small beaks that they can hardly eat and will not rear their own young; he has made families of sheep with so strong a tendency to early maturity and to fatten, that in certain pastures they cannot live from their extreme liability to inflammation; he has made (_i.e._ selected) sub-varieties of plants with a tendency to such early growth that they are frequently killed by the spring frosts; he has made a breed of cows having calves with such large hinder quarters that they are born with great difficulty, often to the death of their mothers{208}; the breeders were compelled to remedy this by the selection of a breeding stock with smaller hinder quarters; in such a case, however, it is possible by long patience and great loss, a remedy might have been found in selecting cows capable of giving birth to calves with large hinder quarters, for in human kind there <are> no doubt hereditary bad and good confinements. Besides the limits already specified, there can be little doubt that the variation of different parts of the frame are connected together by many laws{209}: thus the two sides of the body, in health and disease, seem almost always to vary together: it has been asserted by breeders that if the head is much elongated, the bones of the extremities will likewise be so; in seedling-apples large leaves and fruit generally go together, and serve the horticulturalist as some guide in his selection; we can here see the reason, as the fruit is only a metamorphosed leaf. In animals the teeth and hair seem connected, for the hairless Chinese dog is almost toothless. Breeders believe that one part of the frame or function being increased causes other parts to decrease: they dislike great horns and great bones as so much flesh lost; in hornless breeds of cattle certain bones of the head become more developed: it is said that fat accumulating in one part checks its accumulation in another, and likewise checks the action of the udder. The whole organization is so connected that it is probable there are many conditions determining the variation of each part, and causing other parts to vary with it; and man in making new races must be limited and ruled by all such laws. {208} _Var. under Dom._, Ed. ii. vol. II. p. 211. {209} This discussion corresponds to the _Origin_, Ed. i. pp. 11 and 143, vi. pp. 13 and 177. _In what consists Domestication._ In this chapter we have treated of variation under domestication, and it now remains to consider in what does this power of domestication consist{210}, a subject of considerable difficulty. Observing that organic beings of almost every class, in all climates, countries, and times, have varied when long bred under domestication, we must conclude that the influence is of some very general nature{211}. Mr Knight alone, as far as I know, has tried to define it; he believes it consists of an excess of food, together with transport to a more genial climate, or protection from its severities. I think we cannot admit this latter proposition, for we know how many vegetable products, aborigines of this country, here vary, when cultivated without any protection from the weather; and some of our variable trees, as apricots, peaches, have undoubtedly been derived from a more genial climate. There appears to be much more truth in the doctrine of excess of food being the cause, though I much doubt whether this is the sole cause, although it may well be requisite for the kind of variation desired by man, namely increase of size and vigour. No doubt horticulturalists, when they wish to raise new seedlings, often pluck off all the flower-buds, except a few, or remove the whole during one season, so that a great stock of nutriment may be thrown into the flowers which are to seed. When plants are transported from high-lands, forests, marshes, heaths, into our gardens and greenhouses, there must be a considerable change of food, but it would be hard to prove that there was in every case an excess of the kind proper to the plant. If it be an excess of food, compared with that which the being obtained in its natural state{212}, the effects continue for an improbably long time; during how many ages has wheat been cultivated, and cattle and sheep reclaimed, and we cannot suppose their _amount_ of food has gone on increasing, nevertheless these are amongst the most variable of our domestic productions. It has been remarked (Marshall) that some of the most highly kept breeds of sheep and cattle are truer or less variable than the straggling animals of the poor, which subsist on commons, and pick up a bare subsistence{213}. In the case of forest-trees raised in nurseries, which vary more than the same trees do in their aboriginal forests, the cause would seem simply to lie in their not having to struggle against other trees and weeds, which in their natural state doubtless would limit the conditions of their existence. It appears to me that the power of domestication resolves itself into the accumulated effects of a change of all or some of the natural conditions of the life of the species, often associated with excess of food. These conditions moreover, I may add, can seldom remain, owing to the mutability of the affairs, habits, migrations, and knowledge of man, for very long periods the same. I am the more inclined to come to this conclusion from finding, as we shall hereafter show, that changes of the natural conditions of existence seem peculiarly to affect the action of the reproductive system{214}. As we see that hybrids and mongrels, after the first generation, are apt to vary much, we may at least conclude that variability does not altogether depend on excess of food. {210} See _Origin_, Ed. i. p. 7, vi. p. 7. {211} <Note in the original.> "Isidore G. St Hilaire insists that breeding in captivity essential element. Schleiden on alkalies. <See _Var. under Dom._, Ed. ii. vol. II. p. 244, note 10.> What is it in domestication which causes variation?" {212} <Note in the original.> "It appears that slight changes of condition <are> good for health; that more change affects the generative system, so that variation results in the offspring; that still more change checks or destroys fertility not of the offspring." Compare the _Origin_, Ed. i. p. 9, vi. p. 11. What the meaning of "not of the offspring" may be is not clear. {213} In the _Origin_, Ed. i. p. 41, vi. p. 46 the question is differently treated; it is pointed out that a large stock of individuals gives a better chance of available variations occurring. Darwin quotes from Marshall that sheep in small lots can never be improved. This comes from Marshall's _Review of the Reports to the Board of Agriculture_, 1808, p. 406. In this Essay the name Marshall occurs in the margin. Probably this refers to _loc. cit._ p. 200, where unshepherded sheep in many parts of England are said to be similar owing to mixed breeding not being avoided. {214} See _Origin_, Ed. i. p. 8, vi. p. 8. After these views, it may be asked how it comes that certain animals and plants, which have been domesticated for a considerable length of time, and transported from very different conditions of existence, have not varied much, or scarcely at all; for instance, the ass, peacock, guinea-fowl, asparagus, Jerusalem artichoke{215}. I have already said that probably different species, like different sub-varieties, possess different degrees of tendency to vary; but I am inclined to attribute in these cases the want of numerous races less to want of variability than to selection not having been practised on them. No one will take the pains to select without some corresponding object, either of use or amusement; the individuals raised must be tolerably numerous, and not so precious, but that he may freely destroy those not answering to his wishes. If guinea-fowls or peacocks{216} became "fancy" birds, I cannot doubt that after some generations several breeds would be raised. Asses have not been worked on from mere neglect; but they differ in _some_ degree in different countries. The insensible selection, due to different races of mankind preserving those individuals most useful to them in their different circumstances, will apply only to the oldest and most widely domesticated animals. In the case of plants, we must put entirely out of the case those exclusively (or almost so) propagated by cuttings, layers or tubers, such as the Jerusalem artichoke and laurel; and if we put on one side plants of little ornament or use, and those which are used at so early a period of their growth that no especial characters signify, as asparagus{217} and seakale, I can think of none long cultivated which have not varied. In no case ought we to expect to find as much variation in a race when it alone has been formed, as when several have been formed, for their crossing and recrossing will greatly increase their variability. {215} See _Origin_, Ed. i. p. 42, vi. p. 48. {216} <Note in the original.> There are white peacocks. {217} <Note in the original.> There are varieties of asparagus. _Summary of first Chapter._ To sum up this chapter. Races are made under domestication: 1st, by the direct effects of the external conditions to which the species is exposed: 2nd, by the indirect effects of the exposure to new conditions, often aided by excess of food, rendering the organization plastic, and by man's selecting and separately breeding certain individuals, or introducing to his stock selected males, or often preserving with care the life of the individuals best adapted to his purposes: 3rd, by crossing and recrossing races already made, and selecting their offspring. After some generations man may relax his care in selection: for the tendency to vary and to revert to ancestral forms will decrease, so that he will have only occasionally to remove or destroy one of the yearly offspring which departs from its type. Ultimately, with a large stock, the effects of free crossing would keep, even without this care, his breed true. By these means man can produce infinitely numerous races, curiously adapted to ends, both most important and most frivolous; at the same time that the effects of the surrounding conditions, the laws of inheritance, of growth, and of variation, will modify and limit his labours. CHAPTER II ON THE VARIATION OF ORGANIC BEINGS IN A WILD STATE; ON THE NATURAL MEANS OF SELECTION; AND ON THE COMPARISON OF DOMESTIC RACES AND TRUE SPECIES Having treated of variation under domestication, we now come to it in a _state of nature_. Most organic beings in a state of nature vary exceedingly little{218}: I put out of the case variations (as stunted plants &c., and sea-shells in brackish water{219}) which are directly the effect of external agencies and which we do not _know are in the breed_{220}, or are _hereditary_. The amount of hereditary variation is very difficult to ascertain, because naturalists (partly from the want of knowledge, and partly from the inherent difficulty of the subject) do not all agree whether certain forms are species or races{221}. Some strongly marked races of plants, comparable with the decided sports of horticulturalists, undoubtedly exist in a state of nature, as is actually known by experiment, for instance in the primrose and cowslip{222}, in two so-called species of dandelion, in two of foxglove{223}, and I believe in some pines. Lamarck has observed that, as long as we confine our attention to one limited country, there is seldom much difficulty in deciding what forms to call species and what varieties; and that it is when collections flow in from all parts of the world that naturalists often feel at a loss to decide the limit of variation. Undoubtedly so it is, yet amongst British plants (and I may add land shells), which are probably better known than any in the world, the best naturalists differ very greatly in the relative proportions of what they call species and what varieties. In many genera of insects, and shells, and plants, it seems almost hopeless to establish which are which. In the higher classes there are less doubts; though we find considerable difficulty in ascertaining what deserve to be called species amongst foxes and wolves, and in some birds, for instance in the case of the white barn-owl. When specimens are brought from different parts of the world, how often do naturalists dispute this same question, as I found with respect to the birds brought from the Galapagos islands. Yarrell has remarked that the individuals of the same undoubted species of birds, from Europe and N. America, usually present slight, indefinable though perceptible differences. The recognition indeed of one animal by another of its kind seems to imply some difference. The disposition of wild animals undoubtedly differs. The variation, such as it is, chiefly affects the same parts in wild organisms as in domestic breeds; for instance, the size, colour, and the external and less important parts. In many species the variability of certain organs or qualities is even stated as one of the specific characters: thus, in plants, colour, size, hairiness, the number of the stamens and pistils, and even their presence, the form of the leaves; the size and form of the mandibles of the males of some insects; the length and curvature of the beak in some birds (as in Opetiorynchus) are variable characters in some species and quite fixed in others. I do not perceive that any just distinction can be drawn between this recognised variability of certain parts in many species and the more general variability of the whole frame in domestic races. {218} In Chapter II of the first edition of the _Origin_ Darwin insists rather on the presence of variability in a state of nature; see, for instance, p. 45, Ed. vi. p. 53, "I am convinced that the most experienced naturalist would be surprised at the number of the cases of variability ... which he could collect on good authority, as I have collected, during a course of years." {219} See _Origin_, Ed. i. p. 44, vi. p. 52. {220} <Note in the original.> Here discuss _what is a species_, sterility can most rarely be told when crossed.--Descent from common stock. {221} <Note in the original.> Give only rule: chain of intermediate forms, and _analogy_; this important. Every Naturalist at first when he gets hold of new variable type is _quite puzzled_ to know what to think species and what variations. {222} The author had not at this time the knowledge of the meaning of dimorphism. {223} <Note in original.> Compare feathered heads in very different birds with spines in Echidna and Hedgehog. <In _Variation under Domestication_, Ed. ii. vol. II. p. 317, Darwin calls attention to laced and frizzled breeds occurring in both fowls and pigeons. In the same way a peculiar form of covering occurs in Echidna and the hedgehog.> Plants under very different climate not varying. Digitalis shows jumps <?> in variation, like Laburnum and Orchis case--in fact hostile cases. Variability of sexual characters alike in domestic and wild. Although the amount of variation be exceedingly small in most organic beings in a state of nature, and probably quite wanting (as far as our senses serve) in the majority of cases; yet considering how many animals and plants, taken by mankind from different quarters of the world for the most diverse purposes, have varied under domestication in every country and in every age, I think we may safely conclude that all organic beings with few exceptions, if capable of being domesticated and bred for long periods, would vary. Domestication seems to resolve itself into a change from the natural conditions of the species [generally perhaps including an increase of food]; if this be so, organisms in a state of nature must _occasionally_, in the course of ages, be exposed to analogous influences; for geology clearly shows that many places must, in the course of time, become exposed to the widest range of climatic and other influences; and if such places be isolated, so that new and better adapted organic beings cannot freely emigrate, the old inhabitants will be exposed to new influences, probably far more varied, than man applies under the form of domestication. Although every species no doubt will soon breed up to the full number which the country will support, yet it is easy to conceive that, on an average, some species may receive an increase of food; for the times of dearth may be short, yet enough to kill, and recurrent only at long intervals. All such changes of conditions from geological causes would be exceedingly slow; what effect the slowness might have we are ignorant; under domestication it appears that the effects of change of conditions accumulate, and then break out. Whatever might be the result of these slow geological changes, we may feel sure, from the means of dissemination common in a lesser or greater degree to every organism taken conjointly with the changes of geology, which are steadily (and sometimes suddenly, as when an isthmus at last separates) in progress, that occasionally organisms must suddenly be introduced into new regions, where, if the conditions of existence are not so foreign as to cause its extermination, it will often be propagated under circumstances still more closely analogous to those of domestication; and therefore we expect will evince a tendency to vary. It appears to me quite _inexplicable_ if this has never happened; but it can happen very rarely. Let us then suppose that an organism by some chance (which might be hardly repeated in 1000 years) arrives at a modern volcanic island in process of formation and not fully stocked with the most appropriate organisms; the new organism might readily gain a footing, although the external conditions were considerably different from its native ones. The effect of this we might expect would influence in some small degree the size, colour, nature of covering &c., and from inexplicable influences even special parts and organs of the body. But we might further (and <this> is far more important) expect that the reproductive system would be affected, as under domesticity, and the structure of the offspring rendered in some degree plastic. Hence almost every part of the body would tend to vary from the typical form in slight degrees, and in no determinate way, and therefore _without selection_ the free crossing of these small variations (together with the tendency to reversion to the original form) would constantly be counteracting this unsettling effect of the extraneous conditions on the reproductive system. Such, I conceive, would be the unimportant result without selection. And here I must observe that the foregoing remarks are equally applicable to that small and admitted amount of variation which has been observed in some organisms in a state of nature; as well as to the above hypothetical variation consequent on changes of condition. Let us now suppose a Being{224} with penetration sufficient to perceive differences in the outer and innermost organization quite imperceptible to man, and with forethought extending over future centuries to watch with unerring care and select for any object the offspring of an organism produced under the foregoing circumstances; I can see no conceivable reason why he could not form a new race (or several were he to separate the stock of the original organism and work on several islands) adapted to new ends. As we assume his discrimination, and his forethought, and his steadiness of object, to be incomparably greater that those qualities in man, so we may suppose the beauty and complications of the adaptations of the new races and their differences from the original stock to be greater than in the domestic races produced by man's agency: the ground-work of his labours we may aid by supposing that the external conditions of the volcanic island, from its continued emergence and the occasional introduction of new immigrants, vary; and thus to act on the reproductive system of the organism, on which he is at work, and so keep its organization somewhat plastic. With time enough, such a Being might rationally (without some unknown law opposed him) aim at almost any result. {224} A corresponding passage occurs in _Origin_, Ed. i. p. 83, vi. p. 101, where however Nature takes the place of the selecting Being. For instance, let this imaginary Being wish, from seeing a plant growing on the decaying matter in a forest and choked by other plants, to give it power of growing on the rotten stems of trees, he would commence selecting every seedling whose berries were in the smallest degree more attractive to tree-frequenting birds, so as to cause a proper dissemination of the seeds, and at the same time he would select those plants which had in the slightest degree more and more power of drawing nutriment from rotten wood; and he would destroy all other seedlings with less of this power. He might thus, in the course of century after century, hope to make the plant by degrees grow on rotten wood, even high up on trees, wherever birds dropped the non-digested seeds. He might then, if the organization of the plant was plastic, attempt by continued selection of chance seedlings to make it grow on less and less rotten wood, till it would grow on sound wood{225}. Supposing again, during these changes the plant failed to seed quite freely from non-impregnation, he might begin selecting seedlings with a little sweeter <or> differently tasted honey or pollen, to tempt insects to visit the flowers regularly: having effected this, he might wish, if it profited the plant, to render abortive the stamens and pistils in different flowers, which he could do by continued selection. By such steps he might aim at making a plant as wonderfully related to other organic beings as is the mistletoe, whose existence absolutely depends on certain insects for impregnation, certain birds for transportal, and certain trees for growth. Furthermore, if the insect which had been induced regularly to visit this hypothetical plant profited much by it, our same Being might wish by selection to modify by gradual selection the insect's structure, so as to facilitate its obtaining the honey or pollen: in this manner he might adapt the insect (always presupposing its organization to be in some degree plastic) to the flower, and the impregnation of the flower to the insect; as is the case with many bees and many plants. {225} The mistletoe is used as an illustration in _Origin_, Ed. i. p. 3, vi. p. 3, but with less detail. Seeing what blind capricious man has actually effected by selection during the few last years, and what in a ruder state he has probably effected without any systematic plan during the last few thousand years, he will be a bold person who will positively put limits to what the supposed Being could effect during whole geological periods. In accordance with the plan by which this universe seems governed by the Creator, let us consider whether there exists any _secondary_ means in the economy of nature by which the process of selection could go on adapting, nicely and wonderfully, organisms, if in ever so small a degree plastic, to diverse ends. I believe such secondary means do exist{226}. {226} <Note in original.> The selection, in cases where adult lives only few hours as Ephemera, must fall on larva--curious speculation of the effect <which> changes in it would bring in parent. _Natural means of Selection{227}._ {227} This section forms part of the joint paper by Darwin and Wallace read before the Linnean Society on July 1, 1858. De Candolle, in an eloquent passage, has declared that all nature is at war, one organism with another, or with external nature. Seeing the contented face of nature, this may at first be well doubted; but reflection will inevitably prove it is too true. The war, however, is not constant, but only recurrent in a slight degree at short periods and more severely at occasional more distant periods; and hence its effects are easily overlooked. It is the doctrine of Malthus applied in most cases with ten-fold force. As in every climate there are seasons for each of its inhabitants of greater and less abundance, so all annually breed; and the moral restraint, which in some small degree checks the increase of mankind, is entirely lost. Even slow-breeding mankind has doubled in 25 years{228}, and if he could increase his food with greater ease, he would double in less time. But for animals, without artificial means, _on an average_ the amount of food for each species must be constant; whereas the increase of all organisms tends to be geometrical, and in a vast majority of cases at an enormous ratio. Suppose in a certain spot there are eight pairs of [robins] birds, and that _only_ four pairs of them annually (including double hatches) rear only four young; and that these go on rearing their young at the same rate: then at the end of seven years (a short life, excluding violent deaths, for any birds) there will be 2048 robins, instead of the original sixteen; as this increase is quite impossible, so we must conclude either that robins do not rear nearly half their young or that the average life of a robin when reared is from accident not nearly seven years. Both checks probably concur. The same kind of calculation applied to all vegetables and animals produces results either more or less striking, but in scarcely a single instance less striking than in man{229}. {228} Occurs in _Origin_, Ed. i. p. 64, vi. p. 79. {229} Corresponds approximately with _Origin_, Ed. i. pp. 64-65, vi. p. 80. Many practical illustrations of this rapid tendency to increase are on record, namely during peculiar seasons, in the extraordinary increase of certain animals, for instance during the years 1826 to 1828, in La Plata, when from drought, some millions of cattle perished, the whole country _swarmed_ with innumerable mice: now I think it cannot be doubted that during the breeding season all the mice (with the exception of a few males or females in excess) ordinarily pair; and therefore that this astounding increase during three years must be attributed to a greater than usual number surviving the first year, and then breeding, and so on, till the third year, when their numbers were brought down to their usual limits on the return of wet weather. Where man has introduced plants and animals into a new country favourable to them, there are many accounts in how surprisingly few years the whole country has become stocked with them. This increase would necessarily stop as soon as the country was fully stocked; and yet we have every reason to believe from what is known of wild animals that _all_ would pair in the spring. In the majority of cases it is most difficult to imagine where the check falls, generally no doubt on the seeds, eggs, and young; but when we remember how impossible even in mankind (so much better known than any other animal) it is to infer from repeated casual observations what the average of life is, or to discover how different the percentage of deaths to the births in different countries, we ought to feel no legitimate surprise at not seeing where the check falls in animals and plants. It should always be remembered that in most cases the checks are yearly recurrent in a small regular degree, and in an extreme degree during occasionally unusually cold, hot, dry, or wet years, according to the constitution of the being in question. Lighten any check in the smallest degree, and the geometrical power of increase in every organism will instantly increase the average numbers of the favoured species. Nature may be compared to a surface, on which rest ten thousand sharp wedges touching each other and driven inwards by incessant blows{230}. Fully to realise these views much reflection is requisite; Malthus on man should be studied; and all such cases as those of the mice in La Plata, of the cattle and horses when first turned out in S. America, of the robins by our calculation, &c., should be well considered: reflect on the enormous multiplying power _inherent and annually in action_ in all animals; reflect on the countless seeds scattered by a hundred ingenious contrivances, year after year, over the whole face of the land; and yet we have every reason to suppose that the average percentage of every one of the inhabitants of a country will _ordinarily_ remain constant. Finally, let it be borne in mind that this average number of individuals (the external conditions remaining the same) in each country is kept up by recurrent struggles against other species or against external nature (as on the borders of the arctic regions{231}, where the cold checks life); and that ordinarily each individual of each species holds its place, either by its own struggle and capacity of acquiring nourishment in some period (from the egg upwards) of its life, or by the struggle of its parents (in short lived organisms, when the main check occurs at long intervals) against and compared with other individuals of the _same_ or _different_ species. {230} This simile occurs in _Origin_, Ed. i. p. 67, not in the later editions. {231} <Note in the original.> In case like mistletoe, it may be asked why not more species, no other species interferes; answer almost sufficient, same causes which check the multiplication of individuals. But let the external conditions of a country change; if in a small degree, the relative proportions of the inhabitants will in most cases simply be slightly changed; but let the number of inhabitants be small, as in an island{232}, and free access to it from other countries be circumscribed; and let the change of condition continue progressing (forming new stations); in such case the original inhabitants must cease to be so perfectly adapted to the changed conditions as they originally were. It has been shown that probably such changes of external conditions would, from acting on the reproductive system, cause the organization of the beings most affected to become, as under domestication, plastic. Now can it be doubted from the struggle each individual (or its parents) has to obtain subsistence that any minute variation in structure, habits, or instincts, adapting that individual better to the new conditions, would tell upon its vigour and health? In the struggle it would have a better _chance_ of surviving, and those of its offspring which inherited the variation, let it be ever so slight, would have a better _chance_ to survive. Yearly more are bred than can survive; the smallest grain in the balance, in the long run, must tell on which death shall fall, and which shall survive{233}. Let this work of selection, on the one hand, and death on the other, go on for a thousand generations; who would pretend to affirm that it would produce no effect, when we remember what in a few years Bakewell effected in cattle and Western in sheep, by this identical principle of selection. {232} See _Origin_, Ed. i. pp. 104, 292, vi. pp. 127, 429. {233} Recognition of the importance of minute differences in the struggle occurs in the Essay of 1842, p. 8 note 3.{Note 59} To give an imaginary example, from changes in progress on an island, let the organization{234} of a canine animal become slightly plastic, which animal preyed chiefly on rabbits, but sometimes on hares; let these same changes cause the number of rabbits very slowly to decrease and the number of hares to increase; the effect of this would be that the fox or dog would be driven to try to catch more hares, and his numbers would tend to decrease; his organization, however, being slightly plastic, those individuals with the lightest forms, longest limbs, and best eye-sight (though perhaps with less cunning or scent) would be slightly favoured, let the difference be ever so small, and would tend to live longer and to survive during that time of the year when food was shortest; they would also rear more young, which young would tend to inherit these slight peculiarities. The less fleet ones would be rigidly destroyed. I can see no more reason to doubt but that these causes in a thousand generations would produce a marked effect, and adapt the form of the fox to catching hares instead of rabbits, than that greyhounds can be improved by selection and careful breeding. So would it be with plants under similar circumstances; if the number of individuals of a species with plumed seeds could be increased by greater powers of dissemination within its own area (that is if the check to increase fell chiefly on the seeds), those seeds which were provided with ever so little more down, or with a plume placed so as to be slightly more acted on by the winds, would in the long run tend to be most disseminated; and hence a greater number of seeds thus formed would germinate, and would tend to produce plants inheriting this slightly better adapted down. {234} See _Origin_, Ed. i. p. 90, vi. p. 110. Besides this natural means of selection, by which those individuals are preserved, whether in their egg or seed or in their mature state, which are best adapted to the place they fill in nature, there is a second agency at work in most bisexual animals tending to produce the same effect, namely the struggle of the males for the females. These struggles are generally decided by the law of battle; but in the case of birds, apparently, by the charms of their song{235}, by their beauty or their power of courtship, as in the dancing rock-thrush of Guiana. Even in the animals which pair there seems to be an excess of males which would aid in causing a struggle: in the polygamous animals{236}, however, as in deer, oxen, poultry, we might expect there would be severest struggle: is it not in the polygamous animals that the males are best formed for mutual war? The most vigorous males, implying perfect adaptation, must generally gain the victory in their several contests. This kind of selection, however, is less rigorous than the other; it does not require the death of the less successful, but gives to them fewer descendants. This struggle falls, moreover, at a time of year when food is generally abundant, and perhaps the effect chiefly produced would be the alteration of sexual characters, and the selection of individual forms, no way related to their power of obtaining food, or of defending themselves from their natural enemies, but of fighting one with another. This natural struggle amongst the males may be compared in effect, but in a less degree, to that produced by those agriculturalists who pay less attention to the careful selection of all the young animals which they breed and more to the occasional use of a choice male{237}. {235} These two forms of sexual selection are given in _Origin_, Ed. i. p. 87, vi. p. 107. The Guiana rock-thrush is given as an example of bloodless competition. {236} <Note in original.> Seals? Pennant about battles of seals. {237} In the Linnean paper of July 1, 1858 the final word is _mate_: but the context shows that it should be _male_; it is moreover clearly so written in the MS. _Differences between "Races" and "Species":--first, in their trueness or variability._ Races{238} produced by these natural means of selection{239} we may expect would differ in some respects from those produced by man. Man selects chiefly by the eye, and is not able to perceive the course of every vessel and nerve, or the form of the bones, or whether the internal structure corresponds to the outside shape. He{240} is unable to select shades of constitutional differences, and by the protection he affords and his endeavours to keep his property alive, in whatever country he lives, he checks, as much as lies in his power, the selecting action of nature, which will, however, go on to a lesser degree with all living things, even if their length of life is not determined by their own powers of endurance. He has bad judgment, is capricious, he does not, or his successors do not, wish to select for the same exact end for hundreds of generations. He cannot always suit the selected form to the properest conditions; nor does he keep those conditions uniform: he selects that which is useful to him, not that best adapted to those conditions in which each variety is placed by him: he selects a small dog, but feeds it highly; he selects a long-backed dog, but does not exercise it in any peculiar manner, at least not during every generation. He seldom allows the most vigorous males to struggle for themselves and propagate, but picks out such as he possesses, or such as he prefers, and not necessarily those best adapted to the existing conditions. Every agriculturalist and breeder knows how difficult it is to prevent an occasional cross with another breed. He often grudges to destroy an individual which departs considerably from the required type. He often begins his selection by a form or sport considerably departing from the parent form. Very differently does the natural law of selection act; the varieties selected differ only slightly from the parent forms{241}; the conditions are constant for long periods and change slowly; rarely can there be a cross; the selection is rigid and unfailing, and continued through many generations; a selection can _never be made_ without the form be _better_ adapted to the conditions than the parent form; the selecting power goes on without caprice, and steadily for thousands of years adapting the form to these conditions. The selecting power is not deceived by external appearances, it tries the being during its whole life; and if less well <?> adapted than its _congeners_, without fail it is destroyed; every part of its structure is thus scrutinised and proved good towards the place in nature which it occupies. {238} In the _Origin_ the author would here have used the word _variety_. {239} The whole of p. 94 and 15 lines of p. 95 are, in the MS., marked through in pencil with vertical lines, beginning at "Races produced, &c." and ending with "to these conditions." {240} See _Origin_, Ed. i. p. 83, vi. p. 102. {241} In the present Essay there is some evidence that the author attributed more to _sports_ than was afterwards the case: but the above passage points the other way. It must always be remembered that many of the minute differences, now considered small mutations, are the small variations on which Darwin conceived selection to act. We have every reason to believe that in proportion to the number of generations that a domestic race is kept free from crosses, and to the care employed in continued steady selection with one end in view, and to the care in not placing the variety in conditions unsuited to it; in such proportion does the new race become "true" or subject to little variation{242}. How incomparably "truer" then would a race produced by the above rigid, steady, natural means of selection, excellently trained and perfectly adapted to its conditions, free from stains of blood or crosses, and continued during thousands of years, be compared with one produced by the feeble, capricious, misdirected and ill-adapted selection of man. Those races of domestic animals produced by savages, partly by the inevitable conditions of their life, and partly unintentionally by their greater care of the individuals most valuable to them, would probably approach closest to the character of a species; and I believe this is the case. Now the characteristic mark of a species, next, if not equal in importance to its sterility when crossed with another species, and indeed almost the only other character (without we beg the question and affirm the essence of a species, is its not having descended from a parent common to any other form), is the similarity of the individuals composing the species, or in the language of agriculturalists their "trueness." {242} See _Var. under Dom._, Ed. ii. vol. II. p. 230. _Difference between "Races" and "Species" in fertility when crossed._ The sterility of species, or of their offspring, when crossed has, however, received more attention than the uniformity in character of the individuals composing the species. It is exceedingly natural that such sterility{243} should have been long thought the certain characteristic of species. For it is obvious that if the allied different forms which we meet with in the same country could cross together, instead of finding a number of distinct species, we should have a confused and blending series. The fact however of a perfect gradation in the degree of sterility between species, and the circumstance of some species most closely allied (for instance many species of crocus and European heaths) refusing to breed together, whereas other species, widely different, and even belonging to distinct genera, as the fowl and the peacock, pheasant and grouse{244}, Azalea and Rhododendron, Thuja and Juniperus, breeding together ought to have caused a doubt whether the sterility did not depend on other causes, distinct from a law, coincident with their creation. I may here remark that the fact whether one species will or will not breed with another is far less important than the sterility of the offspring when produced; for even some domestic races differ so greatly in size (as the great stag-greyhound and lap-dog, or cart-horse and Burmese ponies) that union is nearly impossible; and what is less generally known is, that in plants Kölreuter has shown by hundreds of experiments that the pollen of one species will fecundate the germen of another species, whereas the pollen of this latter will never act on the germen of the former; so that the simple fact of mutual impregnation certainly has no relation whatever to the distinctness in creation of the two forms. When two species are attempted to be crossed which are so distantly allied that offspring are never produced, it has been observed in some cases that the pollen commences its proper action by exserting its tube, and the germen commences swelling, though soon afterwards it decays. In the next stage in the series, hybrid offspring are produced though only rarely and few in number, and these are absolutely sterile: then we have hybrid offspring more numerous, and occasionally, though very rarely, breeding with either parent, as is the case with the common mule. Again, other hybrids, though infertile _inter se_, will breed _quite_ freely with either parent, or with a third species, and will yield offspring generally infertile, but sometimes fertile; and these latter again will breed with either parent, or with a third or fourth species: thus Kölreuter blended together many forms. Lastly it is now admitted by those botanists who have longest contended against the admission, that in certain families the hybrid offspring of many of the species are sometimes perfectly fertile in the first generation when bred together: indeed in some few cases Mr Herbert{245} found that the hybrids were decidedly more fertile than either of their pure parents. There is no way to escape from the admission that the hybrids from some species of plants are fertile, except by declaring that no form shall be considered as a species, if it produces with another species fertile offspring: but this is begging the question{246}. It has often been stated that different species of animals have a sexual repugnance towards each other; I can find no evidence of this; it appears as if they merely did not excite each others passions. I do not believe that in this respect there is any essential distinction between animals and plants; and in the latter there cannot be a feeling of repugnance. {243} <Note in the original.> If domestic animals are descended from several species and _become_ fertile _inter se_, then one can see they gain fertility by becoming adapted to new conditions and certainly domestic animals can withstand changes of climate without loss of fertility in an astonishing manner. {244} See Suchetet, _L'Hybridité dans la Nature_, Bruxelles, 1888, p. 67. In _Var. under Dom._, Ed. ii. vol. II. hybrids between the fowl and the pheasant are mentioned. I can give no information on the other cases. {245} _Origin_, Ed. i. p. 250, vi. p. 370. {246} This was the position of Gärtner and of Kölreuter: see _Origin_, Ed. i. pp. 246-7, vi. pp. 367-8. _Causes of Sterility in Hybrids._ The difference in nature between species which causes the greater or lesser degree of sterility in their offspring appears, according to Herbert and Kölreuter, to be connected much less with external form, size, or structure, than with constitutional peculiarities; by which is meant their adaptation to different climates, food and situation, &c.: these peculiarities of constitution probably affect the entire frame, and no one part in particular{247}. {247} <Note in the original.> Yet this seems introductory to the case of the heaths and crocuses above mentioned. <Herbert observed that crocus does not set seed if transplanted before pollination, but that such treatment after pollination has no sterilising effect. (_Var. under Dom._, Ed. ii. vol. II. p. 148.) On the same page is a mention of the Ericaceæ being subject to contabescence of the anthers. For _Crinum_ see _Origin_, Ed. i. p. 250: for _Rhododenron_ and _Calceolaria_ see p. 251.> From the foregoing facts I think we must admit that there exists a perfect gradation in fertility between species which when crossed are quite fertile (as in Rhododendron, Calceolaria, &c.), and indeed in an extraordinary degree fertile (as in Crinum), and those species which never produce offspring, but which by certain effects (as the exsertion of the pollen-tube) evince their alliance. Hence, I conceive, we must give up sterility, although undoubtedly in a lesser or greater degree of very frequent occurrence, as an unfailing mark by which _species_ can be distinguished from _races_, _i.e._ from those forms which have descended from a common stock. _Infertility from causes distinct from hybridisation._ Let us see whether there are any analogous facts which will throw any light on this subject, and will tend to explain why the offspring of certain species, when crossed, should be sterile, and not others, without requiring a distinct law connected with their creation to that effect. Great numbers, probably a large majority of animals when caught by man and removed from their natural conditions, although taken very young, rendered quite tame, living to a good old age, and apparently quite healthy, seem incapable under these circumstances of breeding{248}. I do not refer to animals kept in menageries, such as at the Zoological Gardens, many of which, however, appear healthy and live long and unite but do not produce; but to animals caught and left partly at liberty in their native country. Rengger{249} enumerates several caught young and rendered tame, which he kept in Paraguay, and which would not breed: the hunting leopard or cheetah and elephant offer other instances; as do bears in Europe, and the 25 species of hawks, belonging to different genera, thousands of which have been kept for hawking and have lived for long periods in perfect vigour. When the expense and trouble of procuring a succession of young animals in a wild state be borne in mind, one may feel sure that no trouble has been spared in endeavours to make them breed. So clearly marked is this difference in different kinds of animals, when captured by man, that St Hilaire makes two great classes of animals useful to man:--the _tame_, which will not breed, and the _domestic_ which will breed in domestication. From certain singular facts we might have supposed that the non-breeding of animals was owing to some perversion of instinct. But we meet with exactly the same class of facts in plants: I do not refer to the large number of cases where the climate does not permit the seed or fruit to ripen, but where the flowers do not "set," owing to some imperfection of the ovule or pollen. The latter, which alone can be distinctly examined, is often manifestly imperfect, as any one with a microscope can observe by comparing the pollen of the Persian and Chinese lilacs{250} with the common lilac; the two former species (I may add) are equally sterile in Italy as in this country. Many of the American bog plants here produce little or no pollen, whilst the Indian species of the same genera freely produce it. Lindley observes that sterility is the bane of the horticulturist{251}: Linnæus has remarked on the sterility of nearly all alpine flowers when cultivated in a lowland district{252}. Perhaps the immense class of double flowers chiefly owe their structure to an excess of food acting on parts rendered slightly sterile and less capable of performing their true function, and therefore liable to be rendered monstrous, which monstrosity, like any other disease, is inherited and rendered common. So far from domestication being in itself unfavourable to fertility, it is well known that when an organism is once capable of submission to such conditions <its> fertility is increased{253} beyond the natural limit. According to agriculturists, slight changes of conditions, that is of food or habitation, and likewise crosses with races slightly different, increase the vigour and probably the fertility of their offspring. It would appear also that even a great change of condition, for instance, transportal from temperate countries to India, in many cases does not in the least affect fertility, although it does health and length of life and the period of maturity. When sterility is induced by domestication it is of the same kind, and varies in degree, exactly as with hybrids: for be it remembered that the most sterile hybrid is no way monstrous; its organs are perfect, but they do not act, and minute microscopical investigations show that they are in the same state as those of pure species in the intervals of the breeding season. The defective pollen in the cases above alluded to precisely resembles that of hybrids. The occasional breeding of hybrids, as of the common mule, may be aptly compared to the most rare but occasional reproduction of elephants in captivity. The cause of many exotic Geraniums producing (although in vigorous health) imperfect pollen seems to be connected with the period when water is given them{254}; but in the far greater majority of cases we cannot form any conjecture on what exact cause the sterility of organisms taken from their natural conditions depends. Why, for instance, the cheetah will not breed whilst the common cat and ferret (the latter generally kept shut up in a small box) do,--why the elephant will not whilst the pig will abundantly--why the partridge and grouse in their own country will not, whilst several species of pheasants, the guinea-fowl from the deserts of Africa and the peacock from the jungles of India, will. We must, however, feel convinced that it depends on some constitutional peculiarities in these beings not suited to their new condition; though not necessarily causing an ill state of health. Ought we then to wonder much that those hybrids which have been produced by the crossing of species with different constitutional tendencies (which tendencies we know to be eminently inheritable) should be sterile: it does not seem improbable that the cross from an alpine and lowland plant should have its constitutional powers deranged, in nearly the same manner as when the parent alpine plant is brought into a lowland district. Analogy, however, is a deceitful guide, and it would be rash to affirm, although it may appear probable, that the sterility of hybrids is due to the constitutional peculiarities of one parent being disturbed by being blended with those of the other parent in exactly the same manner as it is caused in some organic beings when placed by man out of their natural conditions{255}. Although this would be rash, it would, I think, be still rasher, seeing that sterility is no more incidental to _all_ cross-bred productions than it is to all organic beings when captured by man, to assert that the sterility of certain hybrids proved a distinct creation of their parents. {248} <Note in original.> Animals seem more often made sterile by being taken out of their native condition than plants, and so are more sterile when crossed. We have one broad fact that sterility in hybrids is not closely related to external difference, and these are what man alone gets by selection. {249} See _Var. under Dom._, Ed. ii. vol. II. p. 132; for the case of the cheetah see _loc cit._ p. 133. {250} _Var. under Dom._, Ed. ii. vol. II. p. 148. {251} Quoted in the _Origin_, Ed. i. p. 9. {252} See _Var. under Dom._, Ed. ii. vol. II. p. 147. {253} _Var. under Dom._, Ed. ii. vol. II. p. 89. {254} See _Var. under Dom._, Ed. ii. vol. II. p. 147. {255} _Origin_, Ed. i. p. 267, vi. p. 392. This is the principle experimentally investigated in the author's _Cross-and Self-Fertilisation_. But it may be objected{256} (however little the sterility of certain hybrids is connected with the distinct creations of species), how comes it, if species are only races produced by natural selection, that when crossed they so frequently produce sterile offspring, whereas in the offspring of those races confessedly produced by the arts of man there is no one instance of sterility. There is not much difficulty in this, for the races produced by the natural means above explained will be slowly but steadily selected; will be adapted to various and diverse conditions, and to these conditions they will be rigidly confined for immense periods of time; hence we may suppose that they would acquire different constitutional peculiarities adapted to the stations they occupy; and on the constitutional differences between species their sterility, according to the best authorities, depends. On the other hand man selects by external appearance{257}; from his ignorance, and from not having any test at least comparable in delicacy to the natural struggle for food, continued at intervals through the life of each individual, he cannot eliminate fine shades of constitution, dependent on invisible differences in the fluids or solids of the body; again, from the value which he attaches to each individual, he asserts his utmost power in contravening the natural tendency of the most vigorous to survive. Man, moreover, especially in the earlier ages, cannot have kept his conditions of life constant, and in later ages his stock pure. Until man selects two varieties from the same stock, adapted to two climates or to other different external conditions, and confines each rigidly for one or several thousand years to such conditions, always selecting the individuals best adapted to them, he cannot be said to have even commenced the experiment. Moreover, the organic beings which man has longest had under domestication have been those which were of the greatest use to him, and one chief element of their usefulness, especially in the earlier ages, must have been their capacity to undergo sudden transportals into various climates, and at the same time to retain their fertility, which in itself implies that in such respects their constitutional peculiarities were not closely limited. If the opinion already mentioned be correct, that most of the domestic animals in their present state have descended from the fertile commixture of wild races or species, we have indeed little reason now to expect infertility between any cross of stock thus descended. {256} _Origin_, Ed. i. p. 268, vi. p. 398. {257} <Notes in original.> Mere difference of structure no guide to what will or will not cross. First step gained by races keeping apart. <It is not clear where these notes were meant to go.> It is worthy of remark, that as many organic beings, when taken by man out of their natural conditions, have their reproductive system <so> affected as to be incapable of propagation, so, we saw in the first chapter, that although organic beings when taken by man do propagate freely, their offspring after some generations vary or sport to a degree which can only be explained by their reproductive system being <in> some way affected. Again, when species cross, their offspring are generally sterile; but it was found by Kölreuter that when hybrids are capable of breeding with either parent, or with other species, that their offspring are subject after some generations to excessive variation{258}. Agriculturists, also, affirm that the offspring from mongrels, after the first generation, vary much. Hence we see that both sterility and variation in the succeeding generations are consequent both on the removal of individual species from their natural states and on species crossing. The connection between these facts may be accidental, but they certainly appear to elucidate and support each other,--on the principle of the reproductive system of all organic beings being eminently sensitive to any disturbance, whether from removal or commixture, in their constitutional relations to the conditions to which they are exposed. {258} _Origin_, Ed. i. p. 272, vi. p. 404. _Points of Resemblance between "Races" and "Species{259}."_ {259} This section seems not to correspond closely with any in the _Origin_, Ed. i.; in some points it resembles pp. 15, 16, also the section on analogous variation in distinct species, _Origin_, Ed. i. p. 159, vi. p. 194. Races and reputed species agree in some respects, although differing from causes which, we have seen, we can in some degree understand, in the fertility and "trueness" of their offspring. In the first place, there is no clear sign by which to distinguish races from species, as is evident from the great difficulty experienced by naturalists in attempting to discriminate them. As far as external characters are concerned, many of the races which are descended from the same stock differ far more than true species of the same genus; look at the willow-wrens, some of which skilful ornithologists can hardly distinguish from each other except by their nests; look at the wild swans, and compare the distinct species of these genera with the races of domestic ducks, poultry, and pigeons; and so again with plants, compare the cabbages, almonds, peaches and nectarines, &c. with the species of many genera. St Hilaire has even remarked that there is a greater difference in size between races, as in dogs (for he believes all have descended from one stock), than between the species of any one genus; nor is this surprising, considering that amount of food and consequently of growth is the element of change over which man has most power. I may refer to a former statement, that breeders believe the growth of one part or strong action of one function causes a decrease in other parts; for this seems in some degree analogous to the law of "organic compensation{260}," which many naturalists believe holds good. To give an instance of this law of compensation,--those species of Carnivora which have the canine teeth greatly developed have certain molar teeth deficient; or again, in that division of the Crustaceans in which the tail is much developed, the thorax is little so, and the converse. The points of difference between different races is often strikingly analogous to that between species of the same genus: trifling spots or marks of colour{261} (as the bars on pigeons' wings) are often preserved in races of plants and animals, precisely in the same manner as similar trifling characters often pervade all the species of a genus, and even of a family. Flowers in varying their colours often become veined and spotted and the leaves become divided like true species: it is known that the varieties of the same plant never have red, blue and yellow flowers, though the hyacinth makes a very near approach to an exception{262}; and different species of the same genus seldom, though sometimes they have flowers of these three colours. Dun-coloured horses having a dark stripe down their backs, and certain domestic asses having transverse bars on their legs, afford striking examples of a variation analogous in character to the distinctive marks of other species of the same genus. {260} The law of compensation is discussed in the _Origin_, Ed. i. p. 147, vi. p. 182. {261} <Note in original.> Boitard and Corbié on outer edging red in tail of bird,--so bars on wing, white or black or brown, or white edged with black or <illegible>: analogous to marks running through genera but with different colours. Tail coloured in pigeons. {262} <Note in original.> Oxalis and Gentian. <In Gentians blue, yellow and reddish colours occur. In Oxalis yellow, purple, violet and pink.> _External characters of Hybrids and Mongrels._ There is, however, as it appears to me, a more important method of comparison between species and races, namely the character of the offspring{263} when species are crossed and when races are crossed: I believe, in no one respect, except in sterility, is there any difference. It would, I think, be a marvellous fact, if species have been formed by distinct acts of creation, that they should act upon each other in uniting, like races descended from a common stock. In the first place, by repeated crossing one species can absorb and wholly obliterate the characters of another, or of several other species, in the same manner as one race will absorb by crossing another race. Marvellous, that one act of creation should absorb another or even several acts of creation! The offspring of species, that is hybrids, and the offspring of races, that is mongrels, resemble each other in being either intermediate in character (as is most frequent in hybrids) or in resembling sometimes closely one and sometimes the other parent; in both the offspring produced by the same act of conception sometimes differ in their degree of resemblance; both hybrids and mongrels sometimes retain a certain part or organ very like that of either parent, both, as we have seen, become in succeeding generations variable; and this tendency to vary can be transmitted by both; in both for many generations there is a strong tendency to reversion to their ancestral form. In the case of a hybrid laburnum and of a supposed mongrel vine different parts of the same plants took after each of their two parents. In the hybrids from some species, and in the mongrel of some races, the offspring differ according as which of the two species, or of the two races, is the father (as in the common mule and hinny) and which the mother. Some races will breed together, which differ so greatly in size, that the dam often perishes in labour; so it is with some species when crossed; when the dam of one species has borne offspring to the male of another species, her succeeding offspring are sometimes stained (as in Lord Morton's mare by the quagga, wonderful as the fact{264} is) by this first cross; so agriculturists positively affirm is the case when a pig or sheep of one breed has produced offspring by the sire of another breed. {263} This section corresponds roughly to that on _Hybrids and Mongrels compared independently of their fertility_, _Origin_, Ed. i. p. 272, vi. p. 403. The discussion on Gärtner's views, given in the _Origin_, is here wanting. The brief mention of prepotency is common to them both. {264} See _Animals and Plants_, Ed. ii. vol. I. p. 435. The phenomenon of _Telegony_, supposed to be established by this and similar cases, is now generally discredited in consequence of Ewart's experiments. _Summary of second chapter_{265}. {265} The section on p. 109 is an appendix to the summary. Let us sum up this second chapter. If slight variations do occur in organic beings in a state of nature; if changes of condition from geological causes do produce in the course of ages effects analogous to those of domestication on any, however few, organisms; and how can we doubt it,--from what is actually known, and from what may be presumed, since thousands of organisms taken by man for sundry uses, and placed in new conditions, have varied. If such variations tend to be hereditary; and how can we doubt it,--when we see shades of expression, peculiar manners, monstrosities of the strangest kinds, diseases, and a multitude of other peculiarities, which characterise and form, being inherited, the endless races (there are 1200 kinds of cabbages{266}) of our domestic plants and animals. If we admit that every organism maintains its place by an almost periodically recurrent struggle; and how can we doubt it,--when we know that all beings tend to increase in a geometrical ratio (as is instantly seen when the conditions become for a time more favourable); whereas on an average the amount of food must remain constant, if so, there will be a natural means of selection, tending to preserve those individuals with any slight deviations of structure more favourable to the then existing conditions, and tending to destroy any with deviations of an opposite nature. If the above propositions be correct, and there be no law of nature limiting the possible amount of variation, new races of beings will,--perhaps only rarely, and only in some few districts,--be formed. {266} I do not know the authority for this statement. _Limits of Variation._ That a limit to variation does exist in nature is assumed by most authors, though I am unable to discover a single fact on which this belief is grounded{267}. One of the commonest statements is that plants do not become acclimatised; and I have even observed that kinds not raised by seed, but propagated by cuttings, &c., are instanced. A good instance has, however, been advanced in the case of kidney beans, which it is believed are now as tender as when first introduced. Even if we overlook the frequent introduction of seed from warmer countries, let me observe that as long as the seeds are gathered promiscuously from the bed, without continual observation and _careful_ selection of those plants which have stood the climate best during their whole growth, the experiment of acclimatisation has hardly been begun. Are not all those plants and animals, of which we have the greatest number of races, the oldest domesticated? Considering the quite recent progress{268} of systematic agriculture and horticulture, is it not opposed to every fact, that we have exhausted the capacity of variation in our cattle and in our corn,--even if we have done so in some trivial points, as their fatness or kind of wool? Will any one say, that if horticulture continues to flourish during the next few centuries, that we shall not have numerous new kinds of the potato and Dahlia? But take two varieties of each of these plants, and adapt them to certain fixed conditions and prevent any cross for 5000 years, and then again vary their conditions; try many climates and situations; and who{269} will predict the number and degrees of difference which might arise from these stocks? I repeat that we know nothing of any limit to the possible amount of variation, and therefore to the number and differences of the races, which might be produced by the natural means of selection, so infinitely more efficient than the agency of man. Races thus produced would probably be very "true"; and if from having been adapted to different conditions of existence, they possessed different constitutions, if suddenly removed to some new station, they would perhaps be sterile and their offspring would perhaps be infertile. Such races would be undistinguishable from species. But is there any evidence that the species, which surround us on all sides, have been thus produced? This is a question which an examination of the economy of nature we might expect would answer either in the affirmative or negative{270}. {267} In the _Origin_ no limit is placed to variation as far as I know. {268} <Note in original.> History of pigeons shows increase of peculiarities during last years. {269} Compare an obscure passage in the Essay of 1842, p. 14. {270} <Note in original.> Certainly <two pages in the MS.> ought to be here introduced, viz., difficulty in forming such organ, as eye, by selection. <In the _Origin_, Ed. i., a chapter on _Difficulties on Theory_ follows that on _Laws of Variation_, and precedes that on _Instinct_: this was also the arrangement in the Essay of 1842; whereas in the present Essay _Instinct_ follows _Variation_ and precedes _Difficulties_.> CHAPTER III ON THE VARIATION OF INSTINCTS AND OTHER MENTAL ATTRIBUTES UNDER DOMESTICATION AND IN STATE OF NATURE; ON THE DIFFICULTIES IN THIS SUBJECT; AND ON ANALOGOUS DIFFICULTIES WITH RESPECT TO CORPOREAL STRUCTURES _Variation of mental attributes under domestication._ I have as yet only alluded to the mental qualities which differ greatly in different species. Let me here premise that, as will be seen in the Second Part, there is no evidence and consequently no attempt to show that _all_ existing organisms have descended from any one common parent-stock, but that only those have so descended which, in the language of naturalists, are clearly related to each other. Hence the facts and reasoning advanced in this chapter do not apply to the first origin of the senses{271}, or of the chief mental attributes, such as of memory, attention, reasoning, &c., &c., by which most or all of the great related groups are characterised, any more than they apply to the first origin of life, or growth, or the power of reproduction. The application of such facts as I have collected is merely to the differences of the primary mental qualities and of the instincts in the species{272} of the several great groups. In domestic animals every observer has remarked in how great a degree, in the individuals of the same species, the dispositions, namely courage, pertinacity, suspicion, restlessness, confidence, temper, pugnaciousness, affection, care of their young, sagacity, &c., &c., vary. It would require a most able metaphysician to explain how many primary qualities of the mind must be changed to cause these diversities of complex dispositions. From these dispositions being inherited, of which the testimony is unanimous, families and breeds arise, varying in these respects. I may instance the good and ill temper of different stocks of bees and of horses,--the pugnacity and courage of game fowls,--the pertinacity of certain dogs, as bull-dogs, and the sagacity of others,--for restlessness and suspicion compare a wild rabbit reared with the greatest care from its earliest age with the extreme tameness of the domestic breed of the same animal. The offspring of the domestic dogs which have run wild in Cuba{273}, though caught quite young, are most difficult to tame, probably nearly as much so as the original parent-stock from which the domestic dog descended. The habitual "_periods_" of different families of the same species differ, for instance, in the time of year of reproduction, and the period of life when the capacity is acquired, and the hour of roosting (in Malay fowls), &c., &c. These periodical habits are perhaps essentially corporeal, and may be compared to nearly similar habits in plants, which are known to vary extremely. Consensual movements (as called by Müller) vary and are inherited,--such as the cantering and ambling paces in horses, the tumbling of pigeons, and perhaps the handwriting, which is sometimes so similar between father and sons, may be ranked in this class. _Manners_, and even tricks which perhaps are only _peculiar_ manners, according to W. Hunter and my father, are distinctly inherited in cases where children have lost their parent in early infancy. The inheritance of expression, which often reveals the finest shades of character, is familiar to everyone. {271} A similar proviso occurs in the chapter on instinct in _Origin_, Ed. i. p. 207, vi. p. 319. {272} The discussion occurs later in Chapter VII of the _Origin_, Ed. i. than in the present Essay, where moreover it is fuller in some respects. {273} In the margin occurs the name of Poeppig. In _Var. under Dom._, Ed. ii. vol. I. p. 28, the reference to Poeppig on the Cuban dogs contains no mention of the wildness of their offspring. Again the tastes and pleasures of different breeds vary, thus the shepherd-dog delights in chasing the sheep, but has no wish to kill them,--the terrier (see Knight) delights in killing vermin, and the spaniel in finding game. But it is impossible to separate their mental peculiarities in the way I have done: the tumbling of pigeons, which I have instanced as a consensual movement, might be called a trick and is associated with a taste for flying in a close flock at a great height. Certain breeds of fowls have a taste for roosting in trees. The different actions of pointers and setters might have been adduced in the same class, as might the peculiar _manner_ of hunting of the spaniel. Even in the same breed of dogs, namely in fox-hounds, it is the fixed opinion of those best able to judge that the different pups are born with different tendencies; some are best to find their fox in the cover; some are apt to run straggling, some are best to make casts and to recover the lost scent, &c.; and that these peculiarities undoubtedly are transmitted to their progeny. Or again the tendency to point might be adduced as a distinct habit which has become inherited,--as might the tendency of a true sheep dog (as I have been assured is the case) to run round the flock instead of directly at them, as is the case with other young dogs when attempted to be taught. The "transandantes" sheep{274} in Spain, which for some centuries have been yearly taken a journey of several hundred miles from one province to another, know when the time comes, and show the greatest restlessness (like migratory birds in confinement), and are prevented with difficulty from starting by themselves, which they sometimes do, and find their own way. There is a case on good evidence{275} of a sheep which, when she lambed, would return across a mountainous country to her own birth-place, although at other times of year not of a rambling disposition. Her lambs inherited this same disposition, and would go to produce their young on the farm whence their parent came; and so troublesome was this habit that the whole family was destroyed. {274} <Note in original.> Several authors. {275} In the margin "Hogg" occurs as authority for this fact. For the reference, see p. 17, note 4. These facts must lead to the conviction, justly wonderful as it is, that almost infinitely numerous shades of disposition, of tastes, of peculiar movements, and even of individual actions, can be modified or acquired by one individual and transmitted to its offspring. One is forced to admit that mental phenomena (no doubt through their intimate connection with the brain) can be inherited, like infinitely numerous and fine differences of corporeal structure. In the same manner as peculiarities of corporeal structure slowly acquired or lost during mature life (especially cognisant <?> in disease), as well as congenital peculiarities, are transmitted; so it appears to be with the mind. The inherited paces in the horse have no doubt been acquired by compulsion during the lives of the parents: and temper and tameness may be modified in a breed by the treatment which the individuals receive. Knowing that a pig has been taught to point, one would suppose that this quality in pointer-dogs was the simple result of habit, but some facts, with respect to the occasional appearance of a similar quality in other dogs, would make one suspect that it originally appeared in a less perfect degree, "_by chance_," that is from a congenital tendency{276} in the parent of the breed of pointers. One cannot believe that the tumbling, and high flight in a compact body, of one breed of pigeons has been taught; and in the case of the slight differences in the manner of hunting in young fox-hounds, they are doubtless congenital. The inheritance of the foregoing and similar mental phenomena ought perhaps to create less surprise, from the reflection that in no case do individual acts of reasoning, or movements, or other phenomena connected with consciousness, appear to be transmitted. An action, even a very complicated one, when from long practice it is performed unconsciously without any effort (and indeed in the case of many peculiarities of manners opposed to the will) is said, according to a common expression, to be performed "instinctively." Those cases of languages, and of songs, learnt in early childhood and _quite_ forgotten, being _perfectly_ repeated during the unconsciousness of illness, appear to me only a few degrees less wonderful than if they had been transmitted to a second generation{277}. {276} In the _Origin_, Ed. i., he speaks more decidedly against the belief that instincts are hereditary habits, see for instance pp. 209, 214, Ed. vi. pp. 321, 327. He allows, however, something to habit (p. 216). {277} A suggestion of Hering's and S. Butler's views on memory and inheritance. It is not, however, implied that Darwin was inclined to accept these opinions. _Hereditary habits compared with instincts._ The chief characteristics of true instincts appear to be their invariability and non-improvement during the mature age of the individual animal: the absence of knowledge of the end, for which the action is performed, being associated, however, sometimes with a degree of reason; being subject to mistakes and being associated with certain states of the body or times of the year or day. In most of these respects there is a resemblance in the above detailed cases of the mental qualities acquired or modified during domestication. No doubt the instincts of wild animals are more uniform than those habits or qualities modified or recently acquired under domestication, in the same manner and from the same causes that the corporeal structure in this state is less uniform than in beings in their natural conditions. I have seen a young pointer point as fixedly, the first day it was taken out, as any old dog; Magendie says this was the case with a retriever which he himself reared: the tumbling of pigeons is not probably improved by age: we have seen that in the case above given that the young sheep inherited the migratory tendency to their particular birth-place the first time they lambed. This last fact offers an instance of a domestic instinct being associated with a state of body; as do the "transandantes" sheep with a time of year. Ordinarily the acquired instincts of domestic animals seem to require a certain degree of education (as generally in pointers and retrievers) to be perfectly developed: perhaps this holds good amongst wild animals in rather a greater degree than is generally supposed; for instance, in the singing of birds, and in the knowledge of proper herbs in Ruminants. It seems pretty clear that bees transmit knowledge from generation to generation. Lord Brougham{278} insists strongly on ignorance of the end proposed being eminently characteristic of true instincts; and this appears to me to apply to many acquired hereditary habits; for instance, in the case of the young pointer alluded to before, which pointed so steadfastly the first day that we were obliged several times to carry him away{279}. This puppy not only pointed at sheep, at large white stones, and at every little bird, but likewise "backed" the other pointers: this young dog must have been as unconscious for what end he was pointing, namely to facilitate his master's killing game to eat, as is a butterfly which lays her eggs on a cabbage, that her caterpillars would eat the leaves. So a horse that ambles instinctively, manifestly is ignorant that he performs that peculiar pace for the ease of man; and if man had never existed, he would never have ambled. The young pointer pointing at white stones appears to be as much a mistake of its acquired instinct, as in the case of flesh-flies laying their eggs on certain flowers instead of putrifying meat. However true the ignorance of the end may generally be, one sees that instincts are associated with some degree of reason; for instance, in the case of the tailor-bird, who spins threads with which to make her nest <yet> will use artificial threads when she can procure them{280}; so it has been known that an old pointer has broken his point and gone round a hedge to drive out a bird towards his master{281}. {278} Lord Brougham's _Dissertations on Subjects of Science_, etc., 1839, p. 27. {279} This case is more briefly given in the _Origin_, Ed. i. p. 213, vi. p. 326. The simile of the butterfly occurs there also. {280} "A little dose, as Pierre Huber expresses it, of judgment or reason, often comes into play." _Origin_, Ed. i. p. 208, vi. p. 320. {281} In the margin is written "Retriever killing one bird." This refers to the cases given in the _Descent of Man_, 2nd Ed. (in 1 vol.) p. 78, of a retriever being puzzled how to deal with a wounded and a dead bird, killed the former and carried both at once. This was the only known instance of her wilfully injuring game. There is one other quite distinct method by which the instincts or habits acquired under domestication may be compared with those given by nature, by a test of a fundamental kind; I mean the comparison of the mental powers of mongrels and hybrids. Now the instincts, or habits, tastes, and dispositions of one _breed_ of animals, when crossed with another breed, for instance a shepherd-dog with a harrier, are blended and appear in the same curiously mixed degree, both in the first and succeeding generations, exactly as happens when one _species_ is crossed with another{282}. This would hardly be the case if there was any fundamental difference between the domestic and natural instinct{283}; if the former were, to use a metaphorical expression, merely superficial. {282} See _Origin_, Ed. i. p. 214, vi. p. 327. {283} <Note in original.> Give some definition of instinct, or at least give chief attributes. <In _Origin_, Ed. i. p. 207, vi. p. 319, Darwin refuses to define instinct.> The term instinct is often used in <a> sense which implies no more than that the animal does the action in question. Faculties and instincts may I think be imperfectly separated. The mole has the faculty of scratching burrows, and the instinct to apply it. The bird of passage has the faculty of finding its way and the instinct to put it in action at certain periods. It can hardly be said to have the faculty of knowing the time, for it can possess no means, without indeed it be some consciousness of passing sensations. Think over all habitual actions and see whether faculties and instincts can be separated. We have faculty of waking in the night, if an instinct prompted us to do something at certain hour of night or day. Savages finding their way. Wrangel's account--probably a faculty inexplicable by the possessor. There are besides faculties "_means_," as conversion of larvæ into neuters and queens. I think all this generally implied, anyhow useful. <This discussion, which does not occur in the _Origin_, is a first draft of that which follows in the text, p. 123.> _Variation in the mental attributes of wild animals._ With respect to the variation{284} of the mental powers of animals in a wild state, we know that there is a considerable difference in the disposition of different individuals of the same species, as is recognised by all those who have had the charge of animals in a menagerie. With respect to the wildness of animals, that is fear directed particularly against man, which appears to be as true an instinct as the dread of a young mouse of a cat, we have excellent evidence that it is slowly acquired and becomes hereditary. It is also certain that, in a natural state, individuals of the same species lose or do not practice their migratory instincts--as woodcocks in Madeira. With respect to any variation in the more complicated instincts, it is obviously most difficult to detect, even more so than in the case of corporeal structure, of which it has been admitted the variation is exceedingly small, and perhaps scarcely any in the majority of species at any one period. Yet, to take one excellent case of instinct, namely the nests of birds, those who have paid most attention to the subject maintain that not only certain individuals <? species> seem to be able to build very imperfectly, but that a difference in skill may not unfrequently be detected between individuals{285}. Certain birds, moreover, adapt their nests to circumstances; the water-ouzel makes no vault when she builds under cover of a rock--the sparrow builds very differently when its nest is in a tree or in a hole, and the golden-crested wren sometimes suspends its nest below and sometimes places it _on_ the branches of trees. {284} A short discussion of a similar kind occurs in the _Origin_, Ed. i. p. 211, vi. p. 324. {285} This sentence agrees with the MS., but is clearly in need of correction. _Principles of Selection applicable to instincts._ As the instincts of a species are fully as important to its preservation and multiplication as its corporeal structure, it is evident that if there be the slightest congenital differences in the instincts and habits, or if certain individuals during their lives are induced or compelled to vary their habits, and if such differences are in the smallest degree more favourable, under slightly modified external conditions, to their preservation, such individuals must in the long run have a better _chance_ of being preserved and of multiplying{286}. If this be admitted, a series of small changes may, as in the case of corporeal structure, work great changes in the mental powers, habits and instincts of any species. {286} This corresponds to _Origin_, Ed. i. p. 212, vi. p. 325. _Difficulties in the acquirement of complex instincts by Selection._ Every one will at first be inclined to explain (as I did for a long time) that many of the more complicated and wonderful instincts could not be acquired in the manner here supposed{287}. The Second Part of this work is devoted to the general consideration of how far the general economy of nature justifies or opposes the belief that related species and genera are descended from common stocks; but we may here consider whether the instincts of animals offer such a _primâ facie_ case of impossibility of gradual acquirement, as to justify the rejection of any such theory, however strongly it may be supported by other facts. I beg to repeat that I wish here to consider not the _probability_ but the _possibility_ of complicated instincts having been acquired by the slow and long-continued selection of very slight (either congenital or produced by habit) modifications of foregoing simpler instincts; each modification being as useful and necessary, to the species practising it, as the most complicated kind. {287} This discussion is interesting in differing from the corresponding section of the _Origin_, Ed. i. p. 216, vi. p. 330, to the end of the chapter. In the present Essay the subjects dealt with are nest-making instincts, including the egg-hatching habit of the Australian bush-turkey. The power of "shamming death." "Faculty" in relation to instinct. The instinct of lapse of time, and of direction. Bees' cells very briefly given. Birds feeding their young on food differing from their own natural food. In the _Origin_, Ed. i., the cases discussed are the instinct of laying eggs in other birds' nests; the slave-making instinct in ants; the construction of the bee's comb, very fully discussed. First, to take the case of birds'-nests; of existing species (almost infinitely few in comparison with the multitude which must have existed, since the period of the new Red Sandstone of N. America, of whose habits we must always remain ignorant) a tolerably perfect series could be made from eggs laid on the bare ground, to others with a few sticks just laid round them, to a simple nest like the wood-pigeons, to others more and more complicated: now if, as is asserted, there occasionally exist slight differences in the building powers of an individual, and if, which is at least probable, that such differences would tend to be inherited, then we can see that it is at least _possible_ that the nidificatory instincts may have been acquired by the gradual selection, during thousands and thousands of generations, of the eggs and young of those individuals, whose nests were in some degree better adapted to the preservation of their young, under the then existing conditions. One of the most surprising instincts on record is that of the Australian bush-turkey, whose eggs are hatched by the heat generated from a huge pile of fermenting materials, which it heaps together; but here the habits of an allied species show how this instinct _might possibly_ have been acquired. This second species inhabits a tropical district, where the heat of the sun is sufficient to hatch its eggs; this bird, burying its eggs, apparently for concealment, under a lesser heap of rubbish, but of a dry nature, so as not to ferment. Now suppose this bird to range slowly into a climate which was cooler, and where leaves were more abundant, in that case, those individuals, which chanced to have their collecting instinct strongest developed, would make a somewhat larger pile, and the eggs, aided during some colder season, under the slightly cooler climate by the heat of incipient fermentation, would in the long run be more freely hatched and would probably produce young ones with the same more highly developed collecting tendencies; of these again, those with the best developed powers would again tend to rear most young. Thus this strange instinct might _possibly_ be acquired, every individual bird being as ignorant of the laws of fermentation, and the consequent development of heat, as we know they must be. Secondly, to take the case of animals feigning death (as it is commonly expressed) to escape danger. In the case of insects, a perfect series can be shown, from some insects, which momentarily stand still, to others which for a second slightly contract their legs, to others which will remain immovably drawn together for a quarter of an hour, and may be torn asunder or roasted at a slow fire, without evincing the smallest sign of sensation. No one will doubt that the length of time, during which each remains immovable, is well adapted to <favour the insect's> escape <from> the dangers to which it is most exposed, and few will deny the _possibility_ of the change from one degree to another, by the means and at the rate already explained. Thinking it, however, wonderful (though not impossible) that the attitude of death should have been acquired by methods which imply no imitation, I compared several species, when feigning, as is said, death, with others of the same species really dead, and their attitudes were in no one case the same. Thirdly, in considering many instincts it is useful to _endeavour_ to separate the faculty{288} by which they perform it, and the mental power which urges to the performance, which is more properly called an instinct. We have an instinct to eat, we have jaws &c. to give us the faculty to do so. These faculties are often unknown to us: bats, with their eyes destroyed, can avoid strings suspended across a room, we know not at present by what faculty they do this. Thus also, with migratory birds, it is a wonderful instinct which urges them at certain times of the year to direct their course in certain directions, but it is a faculty by which they know the time and find their way. With respect to time{289}, man without seeing the sun can judge to a certain extent of the hour, as must those cattle which come down from the inland mountains to feed on sea-weed left bare at the changing hour of low-water{290}. A hawk (D'Orbigny) seems certainly to have acquired a knowledge of a period of every 21 days. In the cases already given of the sheep which travelled to their birth-place to cast their lambs, and the sheep in Spain which know their time of march{291}, we may conjecture that the tendency to move is associated, we may then call it instinctively, with some corporeal sensations. With respect to direction we can easily conceive how a tendency to travel in a certain course may possibly have been acquired, although we must remain ignorant how birds are able to preserve any direction whatever in a dark night over the wide ocean. I may observe that the power of some savage races of mankind to find their way, although perhaps wholly different from the faculty of birds, is nearly as unintelligible to us. Bellinghausen, a skilful navigator, describes with the utmost wonder the manner in which some Esquimaux guided him to a certain point, by a course never straight, through newly formed hummocks of ice, on a thick foggy day, when he with a compass found it impossible, from having no landmarks, and from their course being so extremely crooked, to preserve any sort of uniform direction: so it is with Australian savages in thick forests. In North and South America many birds slowly travel northward and southward, urged on by the food they find, as the seasons change; let them continue to do this, till, as in the case of the sheep in Spain, it has become an urgent instinctive desire, and they will gradually accelerate their journey. They would cross narrow rivers, and if these were converted by subsidence into narrow estuaries, and gradually during centuries to arms of the sea, still we may suppose their restless desire of travelling onwards would impel them to cross such an arm, even if it had become of great width beyond their span of vision. How they are able to preserve a course in any direction, I have said, is a faculty unknown to us. To give another illustration of the means by which I conceive it _possible_ that the direction of migrations have been determined. Elk and reindeer in N. America annually cross, as if they could marvellously smell or see at the distance of a hundred miles, a wide tract of absolute desert, to arrive at certain islands where there is a scanty supply of food; the changes of temperature, which geology proclaims, render it probable that this desert tract formerly supported some vegetation, and thus these quadrupeds might have been annually led on, till they reached the more fertile spots, and so acquired, like the sheep of Spain, their migratory powers. {288} The distinction between _faculty_ and _instinct_ corresponds in some degree to that between perception of a stimulus and a specific reaction. I imagine that the author would have said that the sensitiveness to light possessed by a plant is _faculty_, while _instinct_ decides whether the plant curves to or from the source of illumination. {289} <Note in the original in an unknown handwriting.> At the time when corn was pitched in the market instead of sold by sample, the geese in the town fields of Newcastle <Staffordshire?> used to know market day and come in to pick up the corn spilt. {290} <Note in original.> Macculloch and others. {291} I can find no reference to the _transandantes_ sheep in Darwin's published work. He was possibly led to doubt the accuracy of the statement on which he relied. For the case of the sheep returning to their birth-place see p. 17, note 4.{Note 91} Fourthly, with respect to the combs of the hive-bee{292}; here again we must look to some faculty or means by which they make their hexagonal cells, without indeed we view these instincts as mere machines. At present such a faculty is quite unknown: Mr Waterhouse supposes that several bees are led by their instinct to excavate a mass of wax to a certain thinness, and that the result of this is that hexagons necessarily remain. Whether this or some other theory be true, some such means they must possess. They abound, however, with true instincts, which are the most wonderful that are known. If we examine the little that is known concerning the habits of other species of bees, we find much simpler instincts: the humble bee merely fills rude balls of wax with honey and aggregates them together with little order in a rough nest of grass. If we knew the instinct of all the bees, which ever had existed, it is not improbable that we should have instincts of every degree of complexity, from actions as simple as a bird making a nest, and rearing her young, to the wonderful architecture and government of the hive-bee; at least such is _possible_, which is all that I am here considering. {292} _Origin_, Ed. i. p. 224, vi. p. 342. Finally, I will briefly consider under the same point of view one other class of instincts, which have often been advanced as truly wonderful, namely parents bringing food to their young which they themselves neither like nor partake of{293};--for instance, the common sparrow, a granivorous bird, feeding its young with caterpillars. We might of course look into the case still earlier, and seek how an instinct in the parent, of feeding its young at all, was first derived; but it is useless to waste time in conjectures on a series of gradations from the young feeding themselves and being slightly and occasionally assisted in their search, to their entire food being brought to them. With respect to the parent bringing a different kind of food from its own kind, we may suppose either that the remote stock, whence the sparrow and other congenerous birds have descended, was insectivorous, and that its own habits and structure have been changed, whilst its ancient instincts with respect to its young have remained unchanged; or we may suppose that the parents have been induced to vary slightly the food of their young, by a slight scarcity of the proper kind (or by the instincts of some individuals not being so truly developed), and in this case those young which were most capable of surviving were necessarily most often preserved, and would themselves in time become parents, and would be similarly compelled to alter their food for their young. In the case of those animals, the young of which feed themselves, changes in their instincts for food, and in their structure, might be selected from slight variations, just as in mature animals. Again, where the food of the young depends on where the mother places her eggs, as in the case of the caterpillars of the cabbage-butterfly, we may suppose that the parent stock of the species deposited her eggs sometimes on one kind and sometimes on another of congenerous plants (as some species now do), and if the cabbage suited the caterpillars better than any other plant, the caterpillars of those butterflies, which had chosen the cabbage, would be most plentifully reared, and would produce butterflies more apt to lay their eggs on the cabbage than on the other congenerous plants. {293} This is an expansion of an obscure passage in the Essay of 1842, p. 19. However vague and unphilosophical these conjectures may appear, they serve, I think, to show that one's first impulse utterly to reject any theory whatever, implying a gradual acquirement of these instincts, which for ages have excited man's admiration, may at least be delayed. Once grant that dispositions, tastes, actions or habits can be slightly modified, either by slight congenital differences (we must suppose in the brain) or by the force of external circumstances, and that such slight modifications can be rendered inheritable,--a proposition which no one can reject,--and it will be difficult to put any limit to the complexity and wonder of the tastes and habits which may _possibly_ be thus acquired. _Difficulties in the acquirement by Selection of complex corporeal structures._ After the past discussion it will perhaps be convenient here to consider whether any particular corporeal organs, or the entire structure of any animals, are so wonderful as to justify the rejection _primâ facie_ of our theory{294}. In the case of the eye, as with the more complicated instincts, no doubt one's first impulse is to utterly reject every such theory. But if the eye from its most complicated form can be shown to graduate into an exceedingly simple state,--if selection can produce the smallest change, and if such a series exists, then it is clear (for in this work we have nothing to do with the first origin of organs in their simplest forms{295}) that it may _possibly_ have been acquired by gradual selection of slight, but in each case, useful deviations{296}. Every naturalist, when he meets with any new and singular organ, always expects to find, and looks for, other and simpler modifications of it in other beings. In the case of the eye, we have a multitude of different forms, more or less simple, not graduating into each other, but separated by sudden gaps or intervals; but we must recollect how incomparably greater would the multitude of visual structures be if we had the eyes of every fossil which ever existed. We shall discuss the probable vast proportion of the extinct to the recent in the succeeding Part. Notwithstanding the large series of existing forms, it is most difficult even to conjecture by what intermediate stages very many simple organs could possibly have graduated into complex ones: but it should be here borne in mind, that a part having originally a wholly different function, may on the theory of gradual selection be slowly worked into quite another use; the gradations of forms, from which naturalists believe in the hypothetical metamorphosis of part of the ear into the swimming bladder in fishes{297}, and in insects of legs into jaws, show the manner in which this is possible. As under domestication, modifications of structure take place, without any continued selection, which man finds very useful, or valuable for curiosity (as the hooked calyx of the teazle, or the ruff round some pigeons' necks), so in a state of nature some small modifications, apparently beautifully adapted to certain ends, may perhaps be produced from the accidents of the reproductive system, and be at once propagated without long-continued selection of small deviations towards that structure{298}. In conjecturing by what stages any complicated organ in a species may have arrived at its present state, although we may look to the analogous organs in other existing species, we should do this merely to aid and guide our imaginations; for to know the real stages we must look only through one line of species, to one ancient stock, from which the species in question has descended. In considering the eye of a quadruped, for instance, though we may look at the eye of a molluscous animal or of an insect, as a proof how simple an organ will serve some of the ends of vision; and at the eye of a fish as a nearer guide of the manner of simplification; we must remember that it is a mere chance (assuming for a moment the truth of our theory) if any existing organic being has preserved any one organ, in exactly the same condition, as it existed in the ancient species at remote geological periods. {294} The difficulties discussed in the _Origin_, Ed. i. p. 171, vi. p. 207, are the rarity of transitional varieties, the origin of the tail of the giraffe; the otter-like polecat (_Mustela vison_); the flying habit of the bat; the penguin and the logger-headed duck; flying fish; the whale-like habit of the bear; the woodpecker; diving petrels; the eye; the swimming bladder; Cirripedes; neuter insects; electric organs. Of these, the polecat, the bat, the woodpecker, the eye, the swimming bladder are discussed in the present Essay, and in addition some botanical problems. {295} In the _Origin_, Ed. vi. p. 275, the author replies to Mivart's criticisms (_Genesis of Species_, 1871), referring especially to that writer's objection "that natural selection is incompetent to account for the incipient stages of useful structures." {296} <The following sentence seems to have been intended for insertion here> "and that each eye throughout the animal kingdom is not only most useful, but _perfect_ for its possessor." {297} _Origin_, Ed. i. p. 190, vi. p. 230. {298} This is one of the most definite statements in the present Essay of the possible importance of _sports_ or what would now be called _mutations_. As is well known the author afterwards doubted whether species could arise in this way. See _Origin_, Ed. v. p. 103, vi. p. 110, also _Life and Letters_, vol. iii. p. 107. The nature or condition of certain structures has been thought by some naturalists to be of no use to the possessor{299}, but to have been formed wholly for the good of other species; thus certain fruit and seeds have been thought to have been made nutritious for certain animals--numbers of insects, especially in their larval state, to exist for the same end--certain fish to be bright coloured to aid certain birds of prey in catching them, &c. Now could this be proved (which I am far from admitting) the theory of natural selection would be quite overthrown; for it is evident that selection depending on the advantage over others of one individual with some slight deviation would never produce a structure or quality profitable only to another species. No doubt one being takes advantage of qualities in another, and may even cause its extermination; but this is far from proving that this quality was produced for such an end. It may be advantageous to a plant to have its seeds attractive to animals, if one out of a hundred or a thousand escapes being digested, and thus aids dissemination: the bright colours of a fish may be of some advantage to it, or more probably may result from exposure to certain conditions in favourable haunts for food, _notwithstanding_ it becomes subject to be caught more easily by certain birds. {299} See _Origin_, Ed. i. p. 210, vi. p. 322, where the question is discussed for the case of instincts with a proviso that the same argument applies to structure. It is briefly stated in its general bearing in _Origin_, Ed. i. p. 87, vi. p. 106. If instead of looking, as above, at certain individual organs, in order to speculate on the stages by which their parts have been matured and selected, we consider an individual animal, we meet with the same or greater difficulty, but which, I believe, as in the case of single organs, rests entirely on our ignorance. It may be asked by what intermediate forms could, for instance, a bat possibly have passed; but the same question might have been asked with respect to the seal, if we had not been familiar with the otter and other semi-aquatic carnivorous quadrupeds. But in the case of the bat, who can say what might have been the habits of some parent form with less developed wings, when we now have insectivorous opossums and herbivorous squirrels fitted for merely gliding through the air{300}. One species of bat is at present partly aquatic in its habits{301}. Woodpeckers and tree-frogs are especially adapted, as their names express, for climbing trees; yet we have species of both inhabiting the open plains of La Plata, where a tree does not exist{302}. I might argue from this circumstance that a structure eminently fitted for climbing trees might descend from forms inhabiting a country where a tree did not exist. Notwithstanding these and a multitude of other well-known facts, it has been maintained by several authors that one species, for instance of the carnivorous order, could not pass into another, for instance into an otter, because in its transitional state its habits would not be adapted to any proper conditions of life; but the jaguar{303} is a thoroughly terrestrial quadruped in its structure, yet it takes freely to the water and catches many fish; will it be said that it is _impossible_ that the conditions of its country might become such that the jaguar should be driven to feed more on fish than they now do; and in that case is it impossible, is it not probable, that any the slightest deviation in its instincts, its form of body, in the width of its feet, and in the extension of the skin (which already unites the base of its toes) would give such individuals a better _chance_ of surviving and propagating young with similar, barely perceptible (though thoroughly exercised), deviations{304}? Who will say what could thus be effected in the course of ten thousand generations? Who can answer the same question with respect to instincts? If no one can, the _possibility_ (for we are not in this chapter considering the _probability_) of simple organs or organic beings being modified by natural selection and the effects of external agencies into complicated ones ought not to be absolutely rejected. {300} <Note in original.> No one will dispute that the gliding is most useful, probably necessary for the species in question. {301} <Note in original.> Is this the Galeopithecus? I forget. <_Galeopithecus_ "or the flying Lemur" is mentioned in the corresponding discussion in the _Origin_, Ed. i. p. 181, vi. p. 217, as formerly placed among the bats. I do not know why it is described as partly aquatic in its habits.> {302} In the _Origin_, Ed. vi. p. 221, the author modified the statement that it _never_ climbs trees; he also inserted a sentence quoting Mr Hudson to the effect that in other districts this woodpecker climbs trees and bores holes. See Mr Darwin's paper, _Zoolog. Soc. Proc._, 1870, and _Life and Letters_, iii. p. 153. {303} Note by the late Alfred Newton. Richardson in _Fauna Boreali-Americana_, i. p. 49. {304} <Note in original.> See Richardson a far better case of a polecat animal <_Mustela vison_>, which half-year is aquatic. <Mentioned in _Origin_, Ed. i. p. 179, vi. p. 216.> PART II{305} ON THE EVIDENCE FAVOURABLE AND OPPOSED TO THE VIEW THAT SPECIES ARE NATURALLY FORMED RACES, DESCENDED FROM COMMON STOCKS {305} In the _Origin_ the division of the work into Parts I and II is omitted. In the MS. the chapters of Part II are numbered afresh, the present being Ch. I of Pt. II. I have thought it best to call it Ch. IV and there is evidence that Darwin had some thought of doing the same. It corresponds to Ch. IX of _Origin_, Ed. i., Ch. X in Ed. vi. CHAPTER IV ON THE NUMBER OF INTERMEDIATE FORMS REQUIRED ON THE THEORY OF COMMON DESCENT; AND ON THEIR ABSENCE IN A FOSSIL STATE I must here premise that, according to the view ordinarily received, the myriads of organisms, which have during past and present times peopled this world, have been created by so many distinct acts of creation. It is impossible to reason concerning the will of the Creator, and therefore, according to this view, we can see no cause why or why not the individual organism should have been created on any fixed scheme. That all the organisms of this world have been produced on a scheme is certain from their general affinities; and if this scheme can be shown to be the same with that which would result from allied organic beings descending from common stocks, it becomes highly improbable that they have been separately created by individual acts of the will of a Creator. For as well might it be said that, although the planets move in courses conformably to the law of gravity, yet we ought to attribute the course of each planet to the individual act of the will of the Creator{306}. It is in every case more conformable with what we know of the government of this earth, that the Creator should have imposed only general laws. As long as no method was known by which races could become exquisitely adapted to various ends, whilst the existence of species was thought to be proved by the sterility{307} of their offspring, it was allowable to attribute each organism to an individual act of creation. But in the two former chapters it has (I think) been shown that the production, under existing conditions, of exquisitely adapted species, is at least _possible_. Is there then any direct evidence in favour <of> or against this view? I believe that the geographical distribution of organic beings in past and present times, the kind of affinity linking them together, their so-called "metamorphic" and "abortive" organs, appear in favour of this view. On the other hand, the imperfect evidence of the continuousness of the organic series, which, we shall immediately see, is required on our theory, is against it; and is the most weighty objection{308}. The evidence, however, even on this point, as far as it goes, is favourable; and considering the imperfection of our knowledge, especially with respect to past ages, it would be surprising if evidence drawn from such sources were not also imperfect. {306} In the Essay of 1842 the author uses astronomy in the same manner as an illustration. In the _Origin_ this does not occur; the reference to the action of secondary causes is more general, _e.g._ Ed. i. p. 488, vi. p. 668. {307} It is interesting to find the argument from sterility given so prominent a place. In a corresponding passage in the _Origin_, Ed. i. p. 480, vi. p. 659, it is more summarily treated. The author gives, as the chief bar to the acceptance of evolution, the fact that "we are always slow in admitting any great change of which we do not see the intermediate steps"; and goes on to quote Lyell on geological action. It will be remembered that the question of sterility remained a difficulty for Huxley. {308} Similar statements occur in the Essay of 1842, p. 24, note 1, and in the _Origin_, Ed. i. p. 299. As I suppose that species have been formed in an analogous manner with the varieties of the domesticated animals and plants, so must there have existed intermediate forms between all the species of the same group, not differing more than recognised varieties differ. It must not be supposed necessary that there should have existed forms exactly intermediate in character between any two species of a genus, or even between any two varieties of a species; but it is necessary that there should have existed every intermediate form between the one species or variety of the common parent, and likewise between the second species or variety, and this same common parent. Thus it does not necessarily follow that there ever has existed <a> series of intermediate sub-varieties (differing no more than the occasional seedlings from the same seed-capsule,) between broccoli and common red cabbage; but it is certain that there has existed, between broccoli and the wild parent cabbage, a series of such intermediate seedlings, and again between red cabbage and the wild parent cabbage: so that the broccoli and red cabbage are linked together, but not _necessarily_ by directly intermediate forms{309}. It is of course possible that there _may_ have been directly intermediate forms, for the broccoli may have long since descended from a common red cabbage, and this from the wild cabbage. So on my theory, it must have been with species of the same genus. Still more must the supposition be avoided that there has necessarily ever existed (though one _may_ have descended from <the> other) directly intermediate forms between any two genera or families--for instance between the genus _Sus_ and the Tapir{310}; although it is necessary that intermediate forms (not differing more than the varieties of our domestic animals) should have existed between Sus and some unknown parent form, and Tapir with this same parent form. The latter may have differed more from Sus and Tapir than these two genera now differ from each other. In this sense, according to our theory, there has been a gradual passage (the steps not being wider apart than our domestic varieties) between the species of the same genus, between genera of the same family, and between families of the same order, and so on, as far as facts, hereafter to be given, lead us; and the number of forms which must have at former periods existed, thus to make good this passage between different species, genera, and families, must have been almost infinitely great. {309} In the _Origin_, Ed. i. p. 280, vi. p. 414 he uses his newly-acquired knowledge of pigeons to illustrate this point. {310} Compare the _Origin_, Ed. i. p. 281, vi. p. 414. What evidence{311} is there of a number of intermediate forms having existed, making a passage in the above sense, between the species of the same groups? Some naturalists have supposed that if every fossil which now lies entombed, together with all existing species, were collected together, a perfect series in every great class would be formed. Considering the enormous number of species requisite to effect this, especially in the above sense of the forms not being _directly_ intermediate between the existing species and genera, but only intermediate by being linked through a common but often widely different ancestor, I think this supposition highly improbable. I am however far from underrating the probable number of fossilised species: no one who has attended to the wonderful progress of palæontology during the last few years will doubt that we as yet have found only an exceedingly small fraction of the species buried in the crust of the earth. Although the almost infinitely numerous intermediate forms in no one class may have been preserved, it does not follow that they have not existed. The fossils which have been discovered, it is important to remark, do tend, the little way they go, to make good the series; for as observed by Buckland they all fall into or between existing groups{312}. Moreover, those that fall between our existing groups, fall in, according to the manner required by our theory, for they do not directly connect two existing species of different groups, but they connect the groups themselves: thus the Pachydermata and Ruminantia are now separated by several characters, <for instance> the Pachydermata{313} have both a tibia and fibula, whilst Ruminantia have only a tibia; now the fossil Macrauchenia has a leg bone exactly intermediate in this respect, and likewise has some other intermediate characters. But the Macrauchenia does not connect any one species of Pachydermata with some one other of Ruminantia but it shows that these two groups have at one time been less widely divided. So have fish and reptiles been at one time more closely connected in some points than they now are. Generally in those groups in which there has been most change, the more ancient the fossil, if not identical with recent, the more often it falls between existing groups, or into small existing groups which now lie between other large existing groups. Cases like the foregoing, of which there are many, form steps, though few and far between, in a series of the kind required by my theory. {311} _Origin_, Ed. i. p. 301, vi. p. 440. {312} _Origin_, Ed. i. p. 329, vi. p. 471. {313} The structure of the Pachyderm leg was a favourite with the author. It is discussed in the Essay of 1842, p. 48. In the present Essay the following sentence in the margin appears to refer to Pachyderms and Ruminants: "There can be no doubt, if we banish all fossils, existing groups stand more separate." The following occurs between the lines "The earliest forms would be such as others could radiate from." As I have admitted the high improbability, that if every fossil were disinterred, they would compose in each of the Divisions of Nature a perfect series of the kind required; consequently I freely admit, that if those geologists are in the right who consider the lowest known formation as contemporaneous with the first appearances of life{314}; or the several formations as at all closely consecutive; or any one formation as containing a nearly perfect record of the organisms which existed during the whole period of its deposition in that quarter of the globe;--if such propositions are to be accepted, my theory must be abandoned. {314} _Origin_, Ed. i. p. 307, vi. p. 448. If the Palæozoic system is really contemporaneous with the first appearance of life, my theory must be abandoned, both inasmuch as it limits _from shortness of time_ the total number of forms which can have existed on this world, and because the organisms, as fish, mollusca{315} and star-fish found in its lower beds, cannot be considered as the parent forms of all the successive species in these classes. But no one has yet overturned the arguments of Hutton and Lyell, that the lowest formations known to us are only those which have escaped being metamorphosed <illegible>; if we argued from some considerable districts, we might have supposed that even the Cretaceous system was that in which life first appeared. From the number of distant points, however, in which the Silurian system has been found to be the lowest, and not always metamorphosed, there are some objections to Hutton's and Lyell's view; but we must not forget that the now existing land forms only 1/5 part of the superficies of the globe, and that this fraction is only imperfectly known. With respect to the fewness of the organisms found in the Silurian and other Palæozoic formations, there is less difficulty, inasmuch as (besides their gradual obliteration) we can expect formations of this vast antiquity to escape entire denudation, only when they have been accumulated over a wide area, and have been subsequently protected by vast superimposed deposits: now this could generally only hold good with deposits accumulating in a wide and deep ocean, and therefore unfavourable to the presence of many living things. A mere narrow and not very thick strip of matter, deposited along a coast where organisms most abound, would have no chance of escaping denudation and being preserved to the present time from such immensely distant ages{316}. {315} <Pencil insertion by the author.> The parent-forms of Mollusca would probably differ greatly from all recent,--it is not directly that any one division of Mollusca would descend from first time unaltered, whilst others had become metamorphosed from it. {316} _Origin_, Ed. i. p. 291, vi. p. 426. If the several known formations are at all nearly consecutive in time, and preserve a fair record of the organisms which have existed, my theory must be abandoned. But when we consider the great changes in mineralogical nature and texture between successive formations, what vast and entire changes in the geography of the surrounding countries must generally have been effected, thus wholly to have changed the nature of the deposits on the same area. What time such changes must have required! Moreover how often has it not been found, that between two conformable and apparently immediately successive deposits a vast pile of water-worn matter is interpolated in an adjoining district. We have no means of conjecturing in many cases how long a period{317} has elapsed between successive formations, for the species are often wholly different: as remarked by Lyell, in some cases probably as long a period has elapsed between two formations as the whole Tertiary system, itself broken by wide gaps. {317} <Note in original.> Reflect on coming in of the Chalk, extending from Iceland to the Crimea. Consult the writings of any one who has particularly attended to any one stage in the Tertiary system (and indeed of every system) and see how deeply impressed he is with the time required for its accumulation{318}. Reflect on the years elapsed in many cases, since the latest beds containing only living species have been formed;--see what Jordan Smith says of the 20,000 years since the last bed, which is above the boulder formation in Scotland, has been upraised; or of the far longer period since the recent beds of Sweden have been upraised 400 feet, what an enormous period the boulder formation must have required, and yet how insignificant are the records (although there has been plenty of elevation to bring up submarine deposits) of the shells, which we know existed at that time. Think, then, over the entire length of the Tertiary epoch, and think over the probable length of the intervals, separating the Secondary deposits. Of these deposits, moreover, those consisting of sand and pebbles have seldom been favourable, either to the embedment or to the preservation of fossils{319}. {318} _Origin_, Ed. i. p. 282, vi. p. 416. {319} _Origin_, Ed. i. pp. 288, 300, vi. pp. 422, 438. Nor can it be admitted as probable that any one Secondary formation contains a fair record even of those organisms which are most easily preserved, namely hard marine bodies. In how many cases have we not certain evidence that between the deposition of apparently closely consecutive beds, the lower one existed for an unknown time as land, covered with trees. Some of the Secondary formations which contain most marine remains appear to have been formed in a wide and not deep sea, and therefore only those marine animals which live in such situations would be preserved{320}. In all cases, on indented rocky coasts, or any other coast, where sediment is not accumulating, although often highly favourable to marine animals, none can be embedded: where pure sand and pebbles are accumulating few or none will be preserved. I may here instance the great western line of the S. American coast{321}, tenanted by many peculiar animals, of which none probably will be preserved to a distant epoch. From these causes, and especially from such deposits as are formed along a line of coast, steep above and below water, being necessarily of little width, and therefore more likely to be subsequently denuded and worn away, we can see why it is improbable that our Secondary deposits contain a fair record of the Marine Fauna of any one period. The East Indian Archipelago offers an area, as large as most of our Secondary deposits, in which there are wide and shallow seas, teeming with marine animals, and in which sediment is accumulating; now supposing that all the hard marine animals, or rather those having hard parts to preserve, were preserved to a future age, excepting those which lived on rocky shores where no sediment or only sand and gravel were accumulating, and excepting those embedded along the steeper coasts, where only a narrow fringe of sediment was accumulating, supposing all this, how poor a notion would a person at a future age have of the Marine Fauna of the present day. Lyell{322} has compared the geological series to a work of which only the few latter but not consecutive chapters have been preserved; and out of which, it may be added, very many leaves have been torn, the remaining ones only illustrating a scanty portion of the Fauna of each period. On this view, the records of anteceding ages confirm my theory; on any other they destroy it. {320} <Note in original.> Neither highest or lowest fish (_i.e._ Myxina <?> or Lepidosiren) could be preserved in intelligible condition in fossils. {321} _Origin_, Ed. i. p. 290, vi. p. 425. {322} See _Origin_, Ed. i. p. 310, vi. p. 452 for Lyell's metaphor. I am indebted to Prof. Judd for pointing out that Darwin's version of the metaphor is founded on the first edition of Lyell's _Principles_, vol. I. and vol. III.; see the Essay of 1842, p. 27. Finally, if we narrow the question into, why do we not find in some instances every intermediate form between any two species? the answer may well be that the average duration of each specific form (as we have good reason to believe) is immense in years, and that the transition could, according to my theory, be effected only by numberless small gradations; and therefore that we should require for this end a most perfect record, which the foregoing reasoning teaches us not to expect. It might be thought that in a vertical section of great thickness in the same formation some of the species ought to be found to vary in the upper and lower parts{323}, but it may be doubted whether any formation has gone on accumulating without any break for a period as long as the duration of a species; and if it had done so, we should require a series of specimens from every part. How rare must be the chance of sediment accumulating for some 20 or 30 thousand years on the same spot{324}, with the bottom subsiding, so that a proper depth might be preserved for any one species to continue living: what an amount of subsidence would be thus required, and this subsidence must not destroy the source whence the sediment continued to be derived. In the case of terrestrial animals, what chance is there when the present time is become a pleistocene formation (at an earlier period than this, sufficient elevation to expose marine beds could not be expected), what chance is there that future geologists will make out the innumerable transitional sub-varieties, through which the short-horned and long-horned cattle (so different in shape of body) have been derived from the same parent stock{325}? Yet this transition has been effected in _the same country_, and in a far _shorter time_, than would be probable in a wild state, both contingencies highly favourable for the future hypothetical geologists being enabled to trace the variation. {323} See _More Letters_, vol. I. pp. 344-7, for Darwin's interest in the celebrated observations of Hilgendorf and Hyatt. {324} This corresponds partly to _Origin_, Ed. i. p. 294, vi. p. 431. {325} _Origin_, Ed. i. p. 299, vi. p. 437. CHAPTER V GRADUAL APPEARANCE AND DISAPPEARANCE OF SPECIES{326} {326} This chapter corresponds to ch. X of _Origin_, Ed. i., vi. ch. XI, "On the geological succession of organic beings." In the Tertiary system, in the last uplifted beds, we find all the species recent and living in the immediate vicinity; in rather older beds we find only recent species, but some not living in the immediate vicinity{327}; we then find beds with two or three or a few more extinct or very rare species; then considerably more extinct species, but with gaps in the regular increase; and finally we have beds with only two or three or not one living species. Most geologists believe that the gaps in the percentage, that is the sudden increments, in the number of the extinct species in the stages of the Tertiary system are due to the imperfection of the geological record. Hence we are led to believe that the species in the Tertiary system have been gradually introduced; and from analogy to carry on the same view to the Secondary formations. In these latter, however, entire groups of species generally come in abruptly; but this would naturally result, if, as argued in the foregoing chapter, these Secondary deposits are separated by wide epochs. Moreover it is important to observe that, with our increase of knowledge, the gaps between the older formations become fewer and smaller; geologists of a few years standing remember how beautifully has the Devonian system{328} come in between the Carboniferous and Silurian formations. I need hardly observe that the slow and gradual appearance of new forms follows from our theory, for to form a new species, an old one must not only be plastic in its organization, becoming so probably from changes in the conditions of its existence, but a place in the natural economy of the district must [be made,] come to exist, for the selection of some new modification of its structure, better fitted to the surrounding conditions than are the other individuals of the same or other species{329}. {327} _Origin_, Ed. i. p. 312, vi. p. 453. {328} In the margin the author has written "Lonsdale." This refers to W. Lonsdale's paper "Notes on the age of the Limestone of South Devonshire," _Geolog. Soc. Trans._, Series 2, vol. V. 1840, p. 721. According to Mr H. B. Woodward (_History of the Geological Society of London_, 1907, p. 107) "Lonsdale's 'important and original suggestion of the existence of an intermediary type of Palæozoic fossils, since called Devonian,' led to a change which was then 'the greatest ever made at one time in the classification of our English formations'." Mr Woodward's quotations are from Murchison and Buckland. {329} <Note in original.> Better begin with this. If species really, after catastrophes, created in showers over world, my theory false. <In the above passage the author is obviously close to his theory of divergence.> In the Tertiary system the same facts, which make us admit as probable that new species have slowly appeared, lead to the admission that old ones have slowly disappeared, not several together, but one after another; and by analogy one is induced to extend this belief to the Secondary and Palæozoic epochs. In some cases, as the subsidence of a flat country, or the breaking or the joining of an isthmus, and the sudden inroad of many new and destructive species, extinction might be locally sudden. The view entertained by many geologists, that each fauna of each Secondary epoch has been suddenly destroyed over the whole world, so that no succession could be left for the production of new forms, is subversive of my theory, but I see no grounds whatever to admit such a view. On the contrary, the law, which has been made out, with reference to distinct epochs, by independent observers, namely, that the wider the geographical range of a species the longer is its duration in time, seems entirely opposed to any universal extermination{330}. The fact of species of mammiferous animals and fish being renewed at a quicker rate than mollusca, though both aquatic; and of these the terrestrial genera being renewed quicker than the marine; and the marine mollusca being again renewed quicker than the Infusorial animalcula, all seem to show that the extinction and renewal of species does not depend on general catastrophes, but on the particular relations of the several classes to the conditions to which they are exposed{331}. {330} Opposite to this passage the author has written "d'Archiac, Forbes, Lyell." {331} This passage, for which the author gives as authorities the names of Lyell, Forbes and Ehrenberg, corresponds in part to the discussion beginning on p. 313 of _Origin_, Ed. i., vi. p. 454. Some authors seem to consider the fact of a few species having survived{332} amidst a number of extinct forms (as is the case with a tortoise and a crocodile out of the vast number of extinct sub-Himalayan fossils) as strongly opposed to the view of species being mutable. No doubt this would be the case, if it were presupposed with Lamarck that there was some inherent tendency to change and development in all species, for which supposition I see no evidence. As we see some species at present adapted to a wide range of conditions, so we may suppose that such species would survive unchanged and unexterminated for a long time; time generally being from geological causes a correlative of changing conditions. How at present one species becomes adapted to a wide range, and another species to a restricted range of conditions, is of difficult explanation. {332} The author gives Falconer as his authority: see _Origin_, Ed. i. p. 313, vi. p. 454. _Extinction of species._ The extinction of the larger quadrupeds, of which we imagine we better know the conditions of existence, has been thought little less wonderful than the appearance of new species; and has, I think, chiefly led to the belief of universal catastrophes. When considering the wonderful disappearance within a late period, whilst recent shells were living, of the numerous great and small mammifers of S. America, one is strongly induced to join with the catastrophists. I believe, however, that very erroneous views are held on this subject. As far as is historically known, the disappearance of species from any one country has been slow--the species becoming rarer and rarer, locally extinct, and finally lost{333}. It may be objected that this has been effected by man's direct agency, or by his indirect agency in altering the state of the country; in this latter case, however, it would be difficult to draw any just distinction between his agency and natural agencies. But we now know in the later Tertiary deposits, that shells become rarer and rarer in the successive beds, and finally disappear: it has happened, also, that shells common in a fossil state, and thought to have been extinct, have been found to be still living species, but very _rare_ ones{334}. If the rule is that organisms become extinct by becoming rarer and rarer, we ought not to view their extinction, even in the case of the larger quadrupeds, as anything wonderful and out of the common course of events. For no naturalist thinks it wonderful that one species of a genus should be rare and another abundant, notwithstanding he be quite incapable of explaining the causes of the comparative rareness{335}. Why is one species of willow-wren or hawk or woodpecker common in England, and another extremely rare: why at the Cape of Good Hope is one species of rhinoceros or antelope far more abundant than other species? Why again is the same species much more abundant in one district of a country than in another district? No doubt there are in each case good causes: but they are unknown and unperceived by us. May we not then safely infer that as certain causes are acting _unperceived_ around us, and are making one species to be common and another exceedingly rare, that they might equally well cause the final extinction of some species without being perceived by us? We should always bear in mind that there is a recurrent struggle for life in every organism, and that in every country a destroying agency is always counteracting the geometrical tendency to increase in every species; and yet without our being able to tell with certainty at what period of life, or at what period of the year, the destruction falls the heaviest. Ought we then to expect to trace the steps by which this destroying power, always at work and scarcely perceived by us, becomes increased, and yet if it continues to increase ever so slowly (without the fertility of the species in question be likewise increased) the average number of the individuals of that species must decrease, and become finally lost. I may give a single instance of a check causing local extermination which might long have escaped discovery{336}; the horse, though swarming in a wild state in La Plata, and likewise under apparently the most unfavourable conditions in the scorched and alternately flooded plains of Caraccas, will not in a wild state extend beyond a certain degree of latitude into the intermediate country of Paraguay; this is owing to a certain fly depositing its eggs on the navels of the foals: as, however, man with a _little_ care can rear horses in a tame state _abundantly_ in Paraguay, the problem of its extinction is probably complicated by the greater exposure of the wild horse to occasional famine from the droughts, to the attacks of the jaguar and other such evils. In the Falkland Islands the check to the _increase_ of the wild horse is said to be loss of the sucking foals{337}, from the stallions compelling the mares to travel across bogs and rocks in search of food: if the pasture on these islands decreased a little, the horse, perhaps, would cease to exist in a wild state, not from the absolute want of food, but from the impatience of the stallions urging the mares to travel whilst the foals were too young. {333} This corresponds approximately to _Origin_, Ed. i. p. 317, vi. p. 458. {334} The case of _Trigonia_, a great Secondary genus of shells surviving in a single species in the Australian seas, is given as an example in the _Origin_, Ed. i. p. 321, vi. p. 463. {335} This point, on which the author laid much stress, is discussed in the _Origin_, Ed. i. p. 319, vi. p. 461. {336} _Origin_, Ed. i. p. 72, vi. p. 89. {337} This case does not occur in the _Origin_, Ed. From our more intimate acquaintance with domestic animals, we cannot conceive their extinction without some glaring agency; we forget that they would undoubtedly in a state of nature (where other animals are ready to fill up their place) be acted on in some part of their lives by a destroying agency, keeping their numbers on an average constant. If the common ox was known only as a wild S. African species, we should feel no surprise at hearing that it was a very rare species; and this rarity would be a stage towards its extinction. Even in man, so infinitely better known than any other inhabitant of this world, how impossible it has been found, without statistical calculations, to judge of the proportions of births and deaths, of the duration of life, and of the increase and decrease of population; and still less of the causes of such changes: and yet, as has so often been repeated, decrease in numbers or rarity seems to be the high-road to extinction. To marvel at the extermination of a species appears to me to be the same thing as to know that illness is the road to death,--to look at illness as an ordinary event, nevertheless to conclude, when the sick man dies, that his death has been caused by some unknown and violent agency{338}. {338} An almost identical sentence occurs in the _Origin_, Ed. i. p. 320, vi. p. 462. In a future part of this work we shall show that, as a general rule, groups of allied species{339} gradually appear and disappear, one after the other, on the face of the earth, like the individuals of the same species: and we shall then endeavour to show the probable cause of this remarkable fact. {339} _Origin_, Ed. i. p. 316, vi. p. 457. CHAPTER VI ON THE GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS IN PAST AND PRESENT TIMES For convenience sake I shall divide this chapter into three sections{340}. In the first place I shall endeavour to state the laws of the distribution of existing beings, as far as our present object is concerned; in the second, that of extinct; and in the third section I shall consider how far these laws accord with the theory of allied species having a common descent. {340} Chapters XI and XII in the _Origin_, Ed. i., vi. chs. XII and XIII ("On geographical distribution") show signs of having been originally one, in the fact that one summary serves for both. The geological element is not separately treated there, nor is there a separate section on "how far these laws accord with the theory, &c." In the MS. the author has here written in the margin "If same species appear at two spot at once, fatal to my theory." See _Origin_, Ed. i. p. 352, vi. p. 499 SECTION FIRST. _Distribution of the inhabitants in the different continents._ In the following discussion I shall chiefly refer to terrestrial mammifers, inasmuch as they are better known; their differences in different countries, strongly marked; and especially as the necessary means of their transport are more evident, and confusion, from the accidental conveyance by man of a species from one district to another district, is less likely to arise. It is known that all mammifers (as well as all other organisms) are united in one great system; but that the different species, genera, or families of the same order inhabit different quarters of the globe. If we divide the land{341} into two divisions, according to the amount of difference, and disregarding the numbers of the terrestrial mammifers inhabiting them, we shall have first Australia including New Guinea; and secondly the rest of the world: if we make a three-fold division, we shall have Australia, S. America, and the rest of the world; I must observe that North America is in some respects neutral land, from possessing some S. American forms, but I believe it is more closely allied (as it certainly is in its birds, plants and shells) with Europe. If our division had been four-fold, we should have had Australia, S. America, Madagascar (though inhabited by few mammifers) and the remaining land: if five-fold, Africa, especially the southern eastern parts, would have to be separated from the remainder of the world. These differences in the mammiferous inhabitants of the several main divisions of the globe cannot, it is well known, be explained by corresponding differences in their conditions{342}; how similar are parts of tropical America and Africa; and accordingly we find some _analogous_ resemblances,--thus both have monkeys, both large feline animals, both large Lepidoptera, and large dung-feeding beetles; both have palms and epiphytes; and yet the essential difference between their productions is as great as between those of the arid plains of the Cape of Good Hope and the grass-covered savannahs of La Plata{343}. Consider the distribution of the Marsupialia, which are eminently characteristic of Australia, and in a lesser degree of S. America; when we reflect that animals of this division, feeding both on animal and vegetable matter, frequent the dry open or wooded plains and mountains of Australia, the humid impenetrable forests of New Guinea and Brazil; the dry rocky mountains of Chile, and the grassy plains of Banda Oriental, we must look to some other cause, than the nature of the country, for their absence in Africa and other quarters of the world. {341} This division of the land into regions does not occur in the _Origin_, Ed. i. {342} _Origin_, Ed. i. p. 346, vi. p. 493. {343} Opposite this passage is written "_not botanically_," in Sir J. D. Hooker's hand. The word _palms_ is underlined three times and followed by three exclamation marks. An explanatory note is added in the margin "singular paucity of palms and epiphytes in Trop. Africa compared with Trop. America and Ind. Or." <=East Indies>. Furthermore it may be observed that _all_ the organisms inhabiting any country are not perfectly adapted to it{344}; I mean by not being perfectly adapted, only that some few other organisms can generally be found better adapted to the country than some of the aborigines. We must admit this when we consider the enormous number of horses and cattle which have run wild during the three last centuries in the uninhabited parts of St Domingo, Cuba, and S. America; for these animals must have supplanted some aboriginal ones. I might also adduce the same fact in Australia, but perhaps it will be objected that 30 or 40 years has not been a sufficient period to test this power of struggling <with> and overcoming the aborigines. We know the European mouse is driving before it that of New Zealand, like the Norway rat has driven before it the old English species in England. Scarcely an island can be named, where casually introduced plants have not supplanted some of the native species: in La Plata the Cardoon covers square leagues of country on which some S. American plants must once have grown: the commonest weed over the whole of India is an introduced Mexican poppy. The geologist who knows that slow changes are in progress, replacing land and water, will easily perceive that even if all the organisms of any country had originally been the best adapted to it, this could hardly continue so during succeeding ages without either extermination, or changes, first in the relative proportional numbers of the inhabitants of the country, and finally in their constitutions and structure. {344} This partly corresponds to _Origin_, Ed. i. p. 337, vi. p. 483. Inspection of a map of the world at once shows that the five divisions, separated according to the greatest amount of difference in the mammifers inhabiting them, are likewise those most widely separated from each other by barriers{345} which mammifers cannot pass: thus Australia is separated from New Guinea and some small adjoining islets only by a narrow and shallow strait; whereas New Guinea and its adjoining islets are cut off from the other East Indian islands by deep water. These latter islands, I may remark, which fall into the great Asiatic group, are separated from each other and the continent only by shallow water; and where this is the case we may suppose, from geological oscillations of level, that generally there has been recent union. South America, including the southern part of Mexico, is cut off from North America by the West Indies, and the great table-land of Mexico, except by a mere fringe of tropical forests along the coast: it is owing, perhaps, to this fringe that N. America possesses some S. American forms. Madagascar is entirely isolated. Africa is also to a great extent isolated, although it approaches, by many promontories and by lines of shallower sea, to Europe and Asia: southern Africa, which is the most distinct in its mammiferous inhabitants, is separated from the northern portion by the Great Sahara Desert and the table-land of Abyssinia. That the distribution of organisms is related to barriers, stopping their progress, we clearly see by comparing the distribution of marine and terrestrial productions. The marine animals being different on the two sides of land tenanted by the same terrestrial animals, thus the shells are wholly different on the opposite sides of the temperate parts of South America{346}, as they are (?) in the Red Sea and the Mediterranean. We can at once perceive that the destruction of a barrier would permit two geographical groups of organisms to fuse and blend into one. But the original cause of groups being different on opposite sides of a barrier can only be understood on the hypothesis of each organism having been created or produced on one spot or area, and afterwards migrating as widely as its means of transport and subsistence permitted it. {345} On the general importance of barriers, see _Origin_, Ed. i. p. 347, vi. p. 494. {346} _Origin_, Ed. i. p. 348, vi. p. 495. _Relation of range in genera and species._ It is generally{347} found, that where a genus or group ranges over nearly the entire world, many of the species composing the group have wide ranges: on the other hand, where a group is restricted to any one country, the species composing it generally have restricted ranges in that country{348}. Thus among mammifers the feline and canine genera are widely distributed, and many of the individual species have enormous ranges [the genus Mus I believe, however, is a strong exception to the rule]. Mr Gould informs me that the rule holds with birds, as in the owl genus, which is mundane, and many of the species range widely. The rule holds also with land and fresh-water mollusca, with butterflies and very generally with plants. As instances of the converse rule, I may give that division of the monkeys which is confined to S. America, and amongst plants, the Cacti, confined to the same continent, the species of both of which have generally narrow ranges. On the ordinary theory of the separate creation of each species, the cause of these relations is not obvious; we can see no reason, because many allied species have been created in the several main divisions of the world, that several of these species should have wide ranges; and on the other hand, that species of the same group should have narrow ranges if all have been created in one main division of the world. As the result of such and probably many other unknown relations, it is found that, even in the same great classes of beings, the different divisions of the world are characterised by either merely different species, or genera, or even families: thus in cats, mice, foxes, S. America differs from Asia and Africa only in species; in her pigs, camels and monkeys the difference is generic or greater. Again, whilst southern Africa and Australia differ more widely in their mammalia than do Africa and S. America, they are more closely (though indeed very distantly) allied in their plants. {347} <Note in original.> The same laws seem to govern distribution of species and genera, and individuals in time and space. <See _Origin_, Ed. i. p. 350, vi. p. 497, also a passage in the last chapter, p. 146.> {348} _Origin_, Ed. i. p. 404, vi. p. 559. _Distribution of the inhabitants in the same continent._ If we now look at the distribution of the organisms in any one of the above main divisions of the world, we shall find it split up into many regions, with all or nearly all their species distinct, but yet partaking of one common character. This similarity of type in the subdivisions of a great region is equally well-known with the dissimilarity of the inhabitants of the several great regions; but it has been less often insisted on, though more worthy of remark. Thus for instance, if in Africa or S. America, we go from south to north{349}, or from lowland to upland, or from a humid to a dryer part, we find wholly different species of those genera or groups which characterise the continent over which we are passing. In these subdivisions we may clearly observe, as in the main divisions of the world, that sub-barriers divide different groups of species, although the opposite sides of such sub-barriers may possess nearly the same climate, and may be in other respects nearly similar: thus it is on the opposite sides of the Cordillera of Chile, and in a lesser degree on the opposite sides of the Rocky mountains. Deserts, arms of the sea, and even rivers form the barriers; mere preoccupied space seems sufficient in several cases: thus Eastern and Western Australia, in the same latitude, with very similar climate and soils, have scarcely a plant, and few animals or birds, in common, although all belong to the peculiar genera characterising Australia. It is in short impossible to explain the differences in the inhabitants, either of the main divisions of the world, or of these sub-divisions, by the differences in their physical conditions, and by the adaptation of their inhabitants. Some other cause must intervene. {349} _Origin_, Ed. i. p. 349, vi. p. 496. We can see that the destruction of sub-barriers would cause (as before remarked in the case of the main divisions) two sub-divisions to blend into one; and we can only suppose that the original difference in the species, on the opposite sides of sub-barriers, is due to the creation or production of species in distinct areas, from which they have wandered till arrested by such sub-barriers. Although thus far is pretty clear, it may be asked, why, when species in the same main division of the world were produced on opposite sides of a sub-barrier, both when exposed to similar conditions and when exposed to widely different influences (as on alpine and lowland tracts, as on arid and humid soils, as in cold and hot climates), have they invariably been formed on a similar type, and that type confined to this one division of the world? Why when an ostrich{350} was produced in the southern parts of America, was it formed on the American type, instead of on the African or on Australian types? Why when hare-like and rabbit-like animals were formed to live on the Savannahs of La Plata, were they produced on the peculiar Rodent type of S. America, instead of on the true{351} hare-type of North America, Asia and Africa? Why when borrowing Rodents, and camel-like animals were formed to tenant the Cordillera, were they formed on the same type{352} with their representatives on the plains? Why were the mice, and many birds of different species on the opposite sides of the Cordillera, but exposed to a very similar climate and soil, created on the same peculiar S. American type? Why were the plants in Eastern and Western Australia, though wholly different as species, formed on the same peculiar Australian types? The generality of the rule, in so many places and under such different circumstances, makes it highly remarkable and seems to demand some explanation. {350} The case of the ostrich (_Rhea_) occurs in the _Origin_, Ed. i. p. 349, vi. p. 496. {351} <Note in original.> There is a hare in S. America,--so bad example. {352} See _Origin_, Ed. i. p. 349, vi. p. 497. _Insular Faunas._ If we now look to the character of the inhabitants of small islands{353}, we shall find that those situated close to other land have a similar fauna with that land{354}, whilst those at a considerable distance from other land often possess an almost entirely peculiar fauna. The Galapagos Archipelago{355} is a remarkable instance of this latter fact; here almost every bird, its one mammifer, its reptiles, land and sea shells, and even fish, are almost all peculiar and distinct species, not found in any other quarter of the world: so are the majority of its plants. But although situated at the distance of between 500 and 600 miles from the S. American coast, it is impossible to even glance at a large part of its fauna, especially at the birds, without at once seeing that they belong to the American type{356}. Hence, in fact, groups of islands thus circumstanced form merely small but well-defined sub-divisions of the larger geographical divisions. But the fact is in such cases far more striking: for taking the Galapagos Archipelago as an instance; in the first place we must feel convinced, seeing that every island is wholly volcanic and bristles with craters, that in a geological sense the whole is of recent origin comparatively with a continent; and as the species are nearly all peculiar, we must conclude that they have in the same sense recently been produced on this very spot; and although in the nature of the soil, and in a lesser degree in the climate, there is a wide difference with the nearer part of the S. American coast, we see that the inhabitants have been formed on the same closely allied type. On the other hand, these islands, as far as their physical conditions are concerned, resemble closely the Cape de Verde volcanic group, and yet how wholly unlike are the productions of these two archipelagoes. The Cape de Verde{357} group, to which may be added the Canary Islands, are allied in their inhabitants (of which many are peculiar species) to the coast of Africa and southern Europe, in precisely the same manner as the Galapagos Archipelago is allied to America. We here clearly see that mere geographical proximity affects, more than any relation of adaptation, the character of species. How many islands in the Pacific exist far more like in their physical conditions to Juan Fernandez than this island is to the coast of Chile, distant 300 miles; why then, except from mere proximity, should this island alone be tenanted by two very peculiar species of humming-birds--that form of birds which is so exclusively American? Innumerable other similar cases might be adduced. {353} For the general problem of Oceanic Islands, see _Origin_, Ed. i. p. 388, vi. p. 541. {354} This is an illustration of the general theory of barriers (_Origin_, Ed. i. p. 347, vi. p. 494). At i. p. 391, vi. p. 544 the question is discussed from the point of view of means of transport. Between the lines, above the words "with that land," the author wrote "Cause, formerly joined, no one doubts after Lyell." {355} _Origin_, Ed. i. p. 390, vi. p. 543. {356} See _Origin_, Ed. i. p. 397, vi. p. 552. {357} The Cape de Verde and Galapagos Archipelagoes are compared in the _Origin_, Ed. i. p. 398, vi. p. 553. See also _Journal of Researches_, 1860, p. 393. The Galapagos Archipelago offers another, even more remarkable, example of the class of facts we are here considering. Most of its genera are, as we have said, American, many of them are mundane, or found everywhere, and some are quite or nearly confined to this archipelago. The islands are of absolutely similar composition, and exposed to the same climate; most of them are in sight of each other; and yet several of the islands are inhabited, each by peculiar species (or in some cases perhaps only varieties) of some of the genera characterising the archipelago. So that the small group of the Galapagos Islands typifies, and follows exactly the same laws in the distribution of its inhabitants, as a great continent. How wonderful it is that two or three closely similar but distinct species of a mocking-thrush{358} should have been produced on three neighbouring and absolutely similar islands; and that these three species of mocking-thrush should be closely related to the other species inhabiting wholly different climates and different districts of America, and only in America. No similar case so striking as this of the Galapagos Archipelago has hitherto been observed; and this difference of the productions in the different islands may perhaps be partly explained by the depth of the sea between them (showing that they could not have been united within recent geological periods), and by the currents of the sea sweeping _straight_ between them,--and by storms of wind being rare, through which means seeds and birds could be blown, or drifted, from one island to another. There are however some similar facts: it is said that the different, though neighbouring islands of the East Indian Archipelago are inhabited by some different species of the same genera; and at the Sandwich group some of the islands have each their peculiar species of the same genera of plants. {358} In the _Origin_, Ed. i. p. 390, a strong point is made of birds which immigrated "with facility and in a body" not having been modified. Thus the author accounts for the small percentage of peculiar "marine birds." Islands standing quite isolated within the intra-tropical oceans have generally very peculiar floras, related, though feebly (as in the case of St Helena{359} where almost every species is distinct), with the nearest continent: Tristan d'Acunha is feebly related, I believe, in its plants, both to Africa and S. America, not by having species in common, but by the genera to which they belong{360}. The floras of the numerous scattered islands of the Pacific are related to each other and to all the surrounding continents; but it has been said, that they have more of an Indo-Asiatic than American character{361}. This is somewhat remarkable, as America is nearer to all the Eastern islands, and lies in the direction of the trade-wind and prevailing currents; on the other hand, all the heaviest gales come from the Asiatic side. But even with the aid of these gales, it is not obvious on the ordinary theory of creation how the possibility of migration (without we suppose, with extreme improbability, that each species with an Indo-Asiatic character has actually travelled from the Asiatic shores, where such species do not now exist) explains this Asiatic character in the plants of the Pacific. This is no more obvious than that (as before remarked) there should exist a relation between the creation of closely allied species in several regions of the world, and the fact of many such species having wide ranges; and on the other hand, of allied species confined to one region of the world having in that region narrow ranges. {359} "The affinities of the St Helena flora are strongly South African." Hooker's _Lecture on Insular Floras_ in the _Gardeners' Chronicle_, Jan. 1867. {360} It is impossible to make out the precise form which the author intended to give to this sentence, but the meaning is clear. {361} This is no doubt true, the flora of the Sandwich group however has marked American affinities. _Alpine Floras._ We will now turn to the floras of mountain-summits which are well known to differ from the floras of the neighbouring lowlands. In certain characters, such as dwarfness of stature, hairiness, &c., the species from the most distant mountains frequently resemble each other,--a kind of analogy like that for instance of the succulency of most desert plants. Besides this analogy, Alpine plants present some eminently curious facts in their distribution. In some cases the summits of mountains, although immensely distant from each other, are clothed by the same identical species{362} which are likewise the same with those growing on the likewise very distant Arctic shores. In other cases, although few or none of the species may be actually identical, they are closely related; whilst the plants of the lowland districts surrounding the two mountains in question will be wholly dissimilar. As mountain-summits, as far as their plants are concerned, are islands rising out of an ocean of land in which the Alpine species cannot live, nor across which is there any known means of transport, this fact appears directly opposed to the conclusion which we have come to from considering the general distribution of organisms both on continents and on islands--namely, that the degree of relationship between the inhabitants of two points depends on the completeness and nature of the barriers between those points{363}. I believe, however, this anomalous case admits, as we shall presently see, of some explanation. We might have expected that the flora of a mountain summit would have presented the same relation to the flora of the surrounding lowland country, which any isolated part of a continent does to the whole, or an island does to the mainland, from which it is separated by a rather wide space of sea. This in fact is the case with the plants clothing the summits of _some_ mountains, which mountains it may be observed are particularly isolated; for instance, all the species are peculiar, but they belong to the forms characteristic of the surrounding continent, on the mountains of Caraccas, of Van Dieman's Land and of the Cape of Good Hope{364}. On some other mountains, for instance <in> Tierra del Fuego and in Brazil, some of the plants though distinct species are S. American forms; whilst others are allied to or are identical with the Alpine species of Europe. In islands of which the lowland flora is distinct <from> but allied to that of the nearest continent, the Alpine plants are sometimes (or perhaps mostly) eminently peculiar and distinct{365}; this is the case on Teneriffe, and in a lesser degree even on some of the Mediterranean islands. {362} See _Origin_, Ed. i. p. 365, vi. p. 515. The present discussion was written before the publication of Forbes' celebrated paper on the same subject; see _Life and Letters_, vol. I. p. 88. {363} The apparent breakdown of the doctrine of barriers is slightly touched on in the _Origin_, Ed. i. p. 365, vi. p. 515. {364} In the _Origin_, Ed. i. p. 375, vi. p. 526, the author points out that on the mountains at the Cape of Good Hope "some few representative European forms are found, which have not been discovered in the inter-tropical parts of Africa." {365} See Hooker's _Lecture on Insular Floras_ in the _Gardeners' Chronicle_, Jan. 1867. If all Alpine floras had been characterised like that of the mountain of Caraccas, or of Van Dieman's Land, &c., whatever explanation is possible of the general laws of geographical distribution would have applied to them. But the apparently anomalous case just given, namely of the mountains of Europe, of some mountains in the United States (Dr Boott) and of the summits of the Himalaya (Royle), having many identical species in common conjointly with the Arctic regions, and many species, though not identical, closely allied, require a separate explanation. The fact likewise of several of the species on the mountains of Tierra del Fuego (and in a lesser degree on the mountains of Brazil) not belonging to American forms, but to those of Europe, though so immensely remote, requires also a separate explanation. _Cause of the similarity in the floras of some distant mountains._ Now we may with confidence affirm, from the number of the then floating icebergs and low descent of the glaciers, that within a period so near that species of shells have remained the same, the whole of Central Europe and of North America (and perhaps of Eastern Asia) possessed a very cold climate; and therefore it is probable that the floras of these districts were the same as the present Arctic one,--as is known to have been to some degree the case with then existing sea-shells, and those now living on the Arctic shores. At this period the mountains must have been covered with ice of which we have evidence in the surfaces polished and scored by glaciers. What then would be the natural and almost inevitable effects of the gradual change into the present more temperate climate{366}? The ice and snow would disappear from the mountains, and as new plants from the more temperate regions of the south migrated northward, replacing the Arctic plants, these latter would crawl{367} up the now uncovered mountains, and likewise be driven northward to the present Arctic shores. If the Arctic flora of that period was a nearly uniform one, as the present one is, then we should have the same plants on these mountain-summits and on the present Arctic shores. On this view the Arctic flora of that period must have been a widely extended one, more so than even the present one; but considering how similar the physical conditions must always be of land bordering on perpetual frost, this does not appear a great difficulty; and may we not venture to suppose that the almost infinitely numerous icebergs, charged with great masses of rocks, soil and _brushwood_{368} and often driven high up on distant beaches, might have been the means of widely distributing the seeds of the same species? {366} In the margin the author has written "(Forbes)." This may have been inserted at a date later than 1844, or it may refer to a work by Forbes earlier than his Alpine paper. {367} See _Origin_, Ed. i. p. 367, vi. p. 517. {368} <Note in original.> Perhaps vitality checked by cold and so prevented germinating. <On the carriage of seeds by icebergs, see _Origin_, Ed. i. p. 363, vi. p. 513.> I will only hazard one other observation, namely that during the change from an extremely cold climate to a more temperate one the conditions, both on lowland and mountain, would be singularly favourable for the diffusion of any existing plants, which could live on land, just freed from the rigour of eternal winter; for it would possess no inhabitants; and we cannot doubt that _preoccupation_{369} is the chief bar to the diffusion of plants. For amongst many other facts, how otherwise can we explain the circumstance that the plants on the opposite, though similarly constituted sides of a wide river in Eastern Europe (as I was informed by Humboldt) should be widely different; across which river birds, swimming quadrupeds and the wind must often transport seeds; we can only suppose that plants already occupying the soil and freely seeding check the germination of occasionally transported seeds. {369} A note by the author gives "many authors" apparently as authority for this statement. At about the same period when icebergs were transporting boulders in N. America as far as 36° south, where the cotton tree now grows in South America, in latitude 42° (where the land is now clothed with forests having an almost tropical aspect with the trees bearing epiphytes and intertwined with canes), the same ice action was going on; is it not then in some degree probable that at this period the whole tropical parts of the two Americas possessed{370} (as Falconer asserts that India did) a more temperate climate? In this case the Alpine plants of the long chain of the Cordillera would have descended much lower and there would have been a broad high-road{371} connecting those parts of North and South America which were then frigid. As the present climate supervened, the plants occupying the districts which now are become in both hemispheres temperate and even semi-tropical must have been driven to the Arctic and Antarctic{372} regions; and only a few of the loftiest points of the Cordillera can have retained their former connecting flora. The transverse chain of Chiquitos might perhaps in a similar manner during the ice-action period have served as a connecting road (though a broken one) for Alpine plants to become dispersed from the Cordillera to the highlands of Brazil. It may be observed that some (though not strong) reasons can be assigned for believing that at about this same period the two Americas were not so thoroughly divided as they now are by the West Indies and tableland of Mexico. I will only further remark that the present most singularly close similarity in the vegetation of the lowlands of Kerguelen's Land{373} and of Tierra del Fuego (Hooker), though so far apart, may perhaps be explained by the dissemination of seeds during this same cold period, by means of icebergs, as before alluded to{374}. {370} Opposite to this passage, in the margin, the author has written:--"too hypothetical." {371} The Cordillera is described as supplying a great line of invasion in the _Origin_, Ed. i. p. 378. {372} This is an approximation to the author's views on trans-tropical migration (_Origin_, Ed. i. pp. 376-8). See Thiselton-Dyer's interesting discussion in _Darwin and Modern Science_, p. 304. {373} See Hooker's _Lecture on Insular Floras_ in the _Gardeners' Chronicle_, Jan. 1867. {374} <Note by the author.> Similarity of flora of coral islands easily explained. Finally, I think we may safely grant from the foregoing facts and reasoning that the anomalous similarity in the vegetation of certain very distant mountain-summits is not in truth opposed to the conclusion of the intimate relation subsisting between proximity in space (in accordance with the means of transport in each class) and the degree of affinity of the inhabitants of any two countries. In the case of several quite isolated mountains, we have seen that the general law holds good. _Whether the same species has been created more than once._ As the fact of the same species of plants having been found on mountain-summits immensely remote has been one chief cause of the belief of some species having been contemporaneously produced or created at two different points{375}, I will here briefly discuss this subject. On the ordinary theory of creation, we can see no reason why on two similar mountain-summits two similar species may not have been created; but the opposite view, independently of its simplicity, has been generally received from the analogy of the general distribution of all organisms, in which (as shown in this chapter) we almost always find that great and continuous barriers separate distinct series; and we are naturally led to suppose that the two series have been separately created. When taking a more limited view we see a river, with a quite similar country on both sides, with one side well stocked with a certain animal and on the other side not one (as is the case with the Bizcacha{376} on the opposite sides of the Plata), we are at once led to conclude that the Bizcacha was produced on some one point or area on the western side of the river. Considering our ignorance of the many strange chances of diffusion by birds (which occasionally wander to immense distances) and quadrupeds swallowing seeds and ova (as in the case of the flying water-beetle which disgorged the eggs of a fish), and of whirlwinds carrying seeds and animals into strong upper currents (as in the case of volcanic ashes and showers of hay, grain and fish{377}), and of the possibility of species having survived for short periods at intermediate spots and afterwards becoming extinct there{378}; and considering our knowledge of the great changes which _have_ taken place from subsidence and elevation in the surface of the earth, and of our ignorance of the greater changes which _may have_ taken place, we ought to be very slow in admitting the probability of double creations. In the case of plants on mountain-summits, I think I have shown how almost necessarily they would, under the past conditions of the northern hemisphere, be as similar as are the plants on the present Arctic shores; and this ought to teach us a lesson of caution. {375} On centres of creation see _Origin_, Ed. i. p. 352, vi. p. 499. {376} In the _Journal of Researches_, Ed. 1860, p. 124, the distribution of the Bizcacha is described as limited by the river Uruguay. The case is not I think given in the _Origin_. {377} In the _Origin_, Ed. i. a special section (p. 356, vi. p. 504) is devoted to _Means of Dispersal_. The much greater prominence given to this subject in the _Origin_ is partly accounted for by the author's experiments being of later date, _i.e._ 1855 (_Life and Letters_, vol. II. p. 53). The carriage of fish by whirlwinds is given in the _Origin_, Ed. i. p. 384, vi. p. 536. {378} The case of islands serving as halting places is given in the _Origin_, Ed. i. p. 357, vi. p. 505. But here the evidence of this having occurred is supposed to be lost by the subsidence of the islands, not merely by the extinction of the species. But the strongest argument against double creations may be drawn from considering the case of mammifers{379} in which, from their nature and from the size of their offspring, the means of distribution are more in view. There are no cases where the same species is found in _very remote_ localities, except where there is a continuous belt of land: the Arctic region perhaps offers the strongest exception, and here we know that animals are transported on icebergs{380}. The cases of lesser difficulty may all receive a more or less simple explanation; I will give only one instance; the nutria{381}, I believe, on the eastern coast of S. America live exclusively in fresh-water rivers, and I was much surprised how they could have got into rivulets, widely apart, on the coast of Patagonia; but on the opposite coast I found these quadrupeds living exclusively in the sea, and hence their migration along the Patagonian coast is not surprising. There is no case of the same mammifer being found on an island far from the coast, and on the mainland, as happens with plants{382}. On the idea of double creations it would be strange if the same species of several plants should have been created in Australia and Europe; and no one instance of the same species of mammifer having been created, or aboriginally existing, in two as nearly remote and equally isolated points. It is more philosophical, in such cases, as that of some plants being found in Australia and Europe, to admit that we are ignorant of the means of transport. I will allude only to one other case, namely, that of the Mydas{383}, an Alpine animal, found only on the distant peaks of the mountains of Java: who will pretend to deny that during the ice period of the northern and southern hemispheres, and when India is believed to have been colder, the climate might not have permitted this animal to haunt a lower country, and thus to have passed along the ridges from summit to summit? Mr Lyell has further observed that, _as in space, so in time_, there is no reason to believe that after the extinction of a species, the self-same form has ever reappeared{384}. I think, then, we may, notwithstanding the many cases of difficulty, conclude with some confidence that every species has been created or produced on a single point or area. {379} "We find no inexplicable cases of the same mammal inhabiting distant points of the world." _Origin_, Ed. i. p. 352, vi. p. 500. See also _Origin_, Ed. i. p. 393, vi. p. 547. {380} <Note by the author.> Many authors. <See _Origin_, Ed. i. p. 394, vi. p. 547.> {381} _Nutria_ is the Spanish for otter, and is now a synonym for _Lutra_. The otter on the Atlantic coast is distinguished by minute differences from the Pacific species. Both forms are said to take to the sea. In fact the case presents no especial difficulties. {382} In _Origin_, Ed. i. p. 394, vi. p. 548, bats are mentioned as an explicable exception to this statement. {383} This reference is doubtless to _Mydaus_, a badger-like animal from the mountains of Java and Sumatra (Wallace, _Geographical Distribution_, ii. p. 199). The instance does not occur in the _Origin_ but the author remarks (_Origin_, Ed. i. p. 376, vi. p. 527) that cases, strictly analogous to the distribution of plants, occur among terrestrial mammals. {384} See _Origin_, Ed. i. p. 313, vi. p. 454. _On the number of species, and of the classes to which they belong in different regions._ The last fact in geographical distribution, which, as far as I can see, in any way concerns the origin of species, relates to the absolute number and nature of the organic beings inhabiting different tracts of land. Although every species is admirably adapted (but not necessarily better adapted than every other species, as we have seen in the great increase of introduced species) to the country and station it frequents; yet it has been shown that the entire difference between the species in distant countries cannot possibly be explained by the difference of the physical conditions of these countries. In the same manner, I believe, neither the number of the species, nor the nature of the great classes to which they belong, can possibly in all cases be explained by the conditions of their country. New Zealand{385}, a linear island stretching over about 700 miles of latitude, with forests, marshes, plains and mountains reaching to the limits of eternal snow, has far more diversified habitats than an equal area at the Cape of Good Hope; and yet, I believe, at the Cape of Good Hope there are, of phanerogamic plants, from five to ten times the number of species as in all New Zealand. Why on the theory of absolute creations should this large and diversified island only have from 400 to 500 (? Dieffenbach) phanerogamic plants? and why should the Cape of Good Hope, characterised by the uniformity of its scenery, swarm with more species of plants than probably any other quarter of the world? Why on the ordinary theory should the Galapagos Islands abound with terrestrial reptiles? and why should many equal-sized islands in the Pacific be without a single one{386} or with only one or two species? Why should the great island of New Zealand be without one mammiferous quadruped except the mouse, and that was probably introduced with the aborigines? Why should not one island (it can be shown, I think, that the mammifers of Mauritius and St Iago have all been introduced) in the open ocean possess a mammiferous quadruped? Let it not be said that quadrupeds cannot live in islands, for we know that cattle, horses and pigs during a long period have run wild in the West Indian and Falkland Islands; pigs at St Helena; goats at Tahiti; asses in the Canary Islands; dogs in Cuba; cats at Ascension; rabbits at Madeira and the Falklands; monkeys at St Iago and the Mauritius; even elephants during a long time in one of the very small Sooloo Islands; and European mice on very many of the smallest islands far from the habitations of man{387}. Nor let it be assumed that quadrupeds are more slowly created and hence that the oceanic islands, which generally are of volcanic formation, are of too recent origin to possess them; for we know (Lyell) that new forms of quadrupeds succeed each other quicker than Mollusca or Reptilia. Nor let it be assumed (though such an assumption would be no explanation) that quadrupeds cannot be created on small islands; for islands not lying in mid-ocean do possess their peculiar quadrupeds; thus many of the smaller islands of the East Indian Archipelago possess quadrupeds; as does Fernando Po on the West Coast of Africa; as the Falkland Islands possess a peculiar wolf-like fox{388}; so do the Galapagos Islands a peculiar mouse of the S. American type. These two last are the most remarkable cases with which I am acquainted; inasmuch as the islands lie further from other land. It is possible that the Galapagos mouse may have been introduced in some ship from the S. American coast (though the species is at present unknown there), for the aboriginal species soon haunts the goods of man, as I noticed in the roof of a newly erected shed in a desert country south of the Plata. The Falkland Islands, though between 200 and 300 miles from the S. American coast, may in one sense be considered as intimately connected with it; for it is certain that formerly many icebergs loaded with boulders were stranded on its southern coast, and the old canoes which are occasionally now stranded, show that the currents still set from Tierra del Fuego. This fact, however, does not explain the presence of the _Canis antarcticus_ on the Falkland Islands, unless we suppose that it formerly lived on the mainland and became extinct there, whilst it survived on these islands, to which it was borne (as happens with its northern congener, the common wolf) on an iceberg, but this fact removes the anomaly of an island, in appearance effectually separated from other land, having its own species of quadruped, and makes the case like that of Java and Sumatra, each having their own rhinoceros. {385} The comparison between New Zealand and the Cape is given in the _Origin_, Ed. i. p. 389, vi. p. 542. {386} In a corresponding discussion in the _Origin_, Ed. i. p. 393, vi. p. 546, stress is laid on the distribution of Batrachians not of reptiles. {387} The whole argument is given--more briefly than here--in the _Origin_, Ed. i. p. 394, vi. p. 547. {388} See _Origin_, Ed i. p. 393, vi. p. 547. The discussion is much fuller in the present Essay. Before summing up all the facts given in this section on the present condition of organic beings, and endeavouring to see how far they admit of explanation, it will be convenient to state all such facts in the past geographical distribution of extinct beings as seem anyway to concern the theory of descent. SECTION SECOND. _Geographical distribution of extinct organisms._ I have stated that if the land of the entire world be divided into (we will say) three sections, according to the amount of difference of the terrestrial mammifers inhabiting them, we shall have three unequal divisions of (1st) Australia and its dependent islands, (2nd) South America, (3rd) Europe, Asia and Africa. If we now look to the mammifers which inhabited these three divisions during the later Tertiary periods, we shall find them almost as distinct as at the present day, and intimately related in each division to the existing forms in that division{389}. This is wonderfully the case with the several fossil Marsupial genera in the caverns of New South Wales and even more wonderfully so in South America, where we have the same peculiar group of monkeys, of a guanaco-like animal, of many rodents, of the Marsupial Didelphys, of Armadilloes and other Edentata. This last family is at present very characteristic of S. America, and in a late Tertiary epoch it was even more so, as is shown by the numerous enormous animals of the Megatheroid family, some of which were protected by an osseous armour like that, but on a gigantic scale, of the recent Armadillo. Lastly, over Europe the remains of the several deer, oxen, bears, foxes, beavers, field-mice, show a relation to the present inhabitants of this region; and the contemporaneous remains of the elephant, rhinoceros, hippopotamus, hyæna, show a relation with the grand Africo-Asiatic division of the world. In Asia the fossil mammifers of the Himalaya (though mingled with forms long extinct in Europe) are equally related to the existing forms of the Africo-Asiatic division; but especially to those of India itself. As the gigantic and now extinct quadrupeds of Europe have naturally excited more attention than the other and smaller remains, the relation between the past and the present mammiferous inhabitants of Europe has not been sufficiently attended to. But in fact the mammifers of Europe are at present nearly as much Africo-Asiatic as they were formerly when Europe had its elephants and rhinoceroses, etc.; Europe neither now nor then possessed peculiar groups as does Australia and S. America. The extinction of certain peculiar forms in one quarter does not make the remaining mammifers of that quarter less related to its own great division of the world: though Tierra del Fuego possesses only a fox, three rodents, and the guanaco, no one (as these all belong to S. American types, but not to the most characteristic forms) would doubt for one minute <as to> classifying this district with S. America; and if fossil Edentata, Marsupials and monkeys were to be found in Tierra del Fuego, it would not make this district more truly S. American than it now is. So it is with Europe{390}, and so far as is known with Asia, for the lately past and present mammifers all belong to the Africo-Asiatic division of the world. In every case, I may add, the forms which a country has is of more importance in geographical arrangement than what it has not. {389} See _Origin_, Ed. i. p. 339, vi. p. 485. {390} In the _Origin_, Ed. i. p. 339, vi. p. 485, which corresponds to this part of the present Essay, the author does not make a separate section for such cases as the occurrence of fossil Marsupials in Europe (_Origin_, Ed. i. p. 340, vi. p. 486) as he does in the present Essay; see the section on _Changes in geographical distribution_, p. 177. We find some evidence of the same general fact in a relation between the recent and the Tertiary sea-shells, in the different main divisions of the marine world. This general and most remarkable relation between the lately past and present mammiferous inhabitants of the three main divisions of the world is precisely the same kind of fact as the relation between the different species of the several sub-regions of any one of the main divisions. As we usually associate great physical changes with the total extinction of one series of beings, and its succession by another series, this identity of relation between the past and the present races of beings in the same quarters of the globe is more striking than the same relation between existing beings in different sub-regions: but in truth we have no reason for supposing that a change in the conditions has in any of these cases supervened, greater than that now existing between the temperate and tropical, or between the highlands and lowlands of the same main divisions, now tenanted by related beings. Finally, then, we clearly see that in each main division of the world the same relation holds good between its inhabitants in time as over space{391}. {391} "We can understand how it is that all the forms of life, ancient and recent, make together one grand system; for all are connected by generation." _Origin_, Ed. i. p. 344, vi. p. 491. _Changes in geographical distribution._ If, however, we look closer, we shall find that even Australia, in possessing a terrestrial Pachyderm, was so far less distinct from the rest of the world than it now is; so was S. America in possessing the Mastodon, horse, [hyæna,]{392} and antelope. N. America, as I have remarked, is now, in its mammifers, in some respects neutral ground between S. America and the great Africo-Asiatic division; formerly, in possessing the horse, Mastodon and three Megatheroid animals, it was more nearly related to S. America; but in the horse and Mastodon, and likewise in having the elephant, oxen, sheep, and pigs, it was as much, if not more, related to the Africo-Asiatic division. Again, northern India was much more closely related (in having the giraffe, hippopotamus, and certain musk-deer) to southern Africa than it now is; for southern and eastern Africa deserve, if we divide the world into five parts, to make one division by itself. Turning to the dawn of the Tertiary period, we must, from our ignorance of other portions of the world, confine ourselves to Europe; and at that period, in the presence of Marsupials{393} and Edentata, we behold an _entire_ blending of those mammiferous forms which now eminently characterise Australia and S. America{394}. {392} The word _hyæna_ is erased. There appear to be no fossil Hyænidæ in S. America. {393} See note 1{390}, p. 175, also _Origin_, Ed. i. p. 340, vi. p. 486. {394} <Note by the author.> And see Eocene European mammals in N. America. If we now look at the distribution of sea-shells, we find the same changes in distribution. The Red Sea and the Mediterranean were more nearly related in these shells than they now are. In different parts of Europe, on the other hand, during the Miocene period, the sea-shells seem to have been more different than at present. In{395} the Tertiary period, according to Lyell, the shells of N. America and Europe were less related than at present, and during the Cretaceous still less like; whereas, during this same Cretaceous period, the shells of India and Europe were more like than at present. But going further back to the Carbonaceous period, in N. America and Europe, the productions were much more like than they now are{396}. These facts harmonise with the conclusions drawn from the present distribution of organic beings, for we have seen, that from species being created in different points or areas, the formation of a barrier would cause or make two distinct geographical areas; and the destruction of a barrier would permit their diffusion{397}. And as long-continued geological changes must both destroy and make barriers, we might expect, the further we looked backwards, the more changed should we find the present distribution. This conclusion is worthy of attention; because, finding in widely different parts of the same main division of the world, and in volcanic islands near them, groups of distinct, but related, species;--and finding that a singularly analogous relation holds good with respect to the beings of past times, when none of the present species were living, a person might be tempted to believe in some mystical relation between certain areas of the world, and the production of certain organic forms; but we now see that such an assumption would have to be complicated by the admission that such a relation, though holding good for long revolutions of years, is not truly persistent. {395} <Note by the author.> All this requires much verification. {396} This point seems to be less insisted on in the _Origin_. {397} _Origin_, Ed. i. p. 356, vi. p. 504. I will only add one more observation to this section. Geologists finding in the most remote period with which we are acquainted, namely in the Silurian period, that the shells and other marine productions{398} in North and South America, in Europe, Southern Africa, and Western Asia, are much more similar than they now are at these distant points, appear to have imagined that in these ancient times the laws of geographical distribution were quite different than what they now are: but we have only to suppose that great continents were extended east and west, and thus did not divide the inhabitants of the temperate and tropical seas, as the continents now do; and it would then become probable that the inhabitants of the seas would be much more similar than they now are. In the immense space of ocean extending from the east coast of Africa to the eastern islands of the Pacific, which space is connected either by lines of tropical coast or by islands not very distant from each other, we know (Cuming) that many shells, perhaps even as many as 200, are common to the Zanzibar coast, the Philippines, and the eastern islands of the Low or Dangerous Archipelago in the Pacific. This space equals that from the Arctic to the Antarctic pole! Pass over the space of quite open ocean, from the Dangerous Archipelago to the west coast of S. America, and every shell is different: pass over the narrow space of S. America, to its eastern shores, and again every shell is different! Many fish, I may add, are also common to the Pacific and Indian Oceans. {398} <Note by the author.> D'Orbigny shows that this is not so. _Summary on the distribution of living and extinct organic beings._ Let us sum up the several facts now given with respect to the past and present geographical distribution of organic beings. In a previous chapter it was shown that species are not exterminated by universal catastrophes, and that they are slowly produced: we have also seen that each species is probably only once produced, on one point or area once in time; and that each diffuses itself, as far as barriers and its conditions of life permit. If we look at any one main division of the land, we find in the different parts, whether exposed to different conditions or to the same conditions, many groups of species wholly or nearly distinct as species, nevertheless intimately related. We find the inhabitants of islands, though distinct as species, similarly related to the inhabitants of the nearest continent; we find in some cases, that even the different islands of one such group are inhabited by species distinct, though intimately related to one another and to those of the nearest continent:--thus typifying the distribution of organic beings over the whole world. We find the floras of distant mountain-summits either very similar (which seems to admit, as shown, of a simple explanation) or very distinct but related to the floras of the surrounding region; and hence, in this latter case, the floras of two mountain-summits, although exposed to closely similar conditions, will be very different. On the mountain-summits of islands, characterised by peculiar faunas and floras, the plants are often eminently peculiar. The dissimilarity of the organic beings inhabiting nearly similar countries is best seen by comparing the main divisions of the world; in each of which some districts may be found very similarly exposed, yet the inhabitants are wholly unlike;--far more unlike than those in very dissimilar districts in the same main division. We see this strikingly in comparing two volcanic archipelagoes, with nearly the same climate, but situated not very far from two different continents; in which case their inhabitants are totally unlike. In the different main divisions of the world, the amount of difference between the organisms, even in the same class, is widely different, each main division having only the species distinct in some families, in other families having the genera distinct. The distribution of aquatic organisms is very different from that of the terrestrial organisms; and necessarily so, from the barriers to their progress being quite unlike. The nature of the conditions in an isolated district will not explain the number of species inhabiting it; nor the absence of one class or the presence of another class. We find that terrestrial mammifers are not present on islands far removed from other land. We see in two regions, that the species though distinct are more or less related, according to the greater or less _possibility_ of the transportal in past and present times of species from one to the other region; although we can hardly admit that all the species in such cases have been transported from the first to the second region, and since have become extinct in the first: we see this law in the presence of the fox on the Falkland Islands; in the European character of some of the plants of Tierra del Fuego; in the Indo-Asiatic character of the plants of the Pacific; and in the circumstance of those genera which range widest having many species with wide ranges; and those genera with restricted ranges having species with restricted ranges. Finally, we find in each of the main divisions of the land, and probably of the sea, that the existing organisms are related to those lately extinct. Looking further backwards we see that the past geographical distribution of organic beings was different from the present; and indeed, considering that geology shows that all our land was once under water, and that where water now extends land is forming, the reverse could hardly have been possible. Now these several facts, though evidently all more or less connected together, must by the creationist (though the geologist may explain some of the anomalies) be considered as so many ultimate facts. He can only say, that it so pleased the Creator that the organic beings of the plains, deserts, mountains, tropical and temperature forests, of S. America, should all have some affinity together; that the inhabitants of the Galapagos Archipelago should be related to those of Chile; and that some of the species on the similarly constituted islands of this archipelago, though most closely related, should be distinct; that all its inhabitants should be totally unlike those of the similarly volcanic and arid Cape de Verde and Canary Islands; that the plants on the summit of Teneriffe should be eminently peculiar; that the diversified island of New Zealand should have not many plants, and not one, or only one, mammifer; that the mammifers of S. America, Australia and Europe should be clearly related to their ancient and exterminated prototypes; and so on with other facts. But it is absolutely opposed to every analogy, drawn from the laws imposed by the Creator on inorganic matter, that facts, when connected, should be considered as ultimate and not the direct consequences of more general laws. SECTION THIRD. _An attempt to explain the foregoing laws of geographical distribution, on the theory of allied species having a common descent._ First let us recall the circumstances most favourable for variation under domestication, as given in the first chapter--viz. 1st, a change, or repeated changes, in the conditions to which the organism has been exposed, continued through several seminal (_i.e._ not by buds or divisions) generations: 2nd, steady selection of the slight varieties thus generated with a fixed end in view: 3rd, isolation as perfect as possible of such selected varieties; that is, the preventing their crossing with other forms; this latter condition applies to all terrestrial animals, to most if not all plants and perhaps even to most (or all) aquatic organisms. It will be convenient here to show the advantage of isolation in the formation of a new breed, by comparing the progress of two persons (to neither of whom let time be of any consequence) endeavouring to select and form some very peculiar new breed. Let one of these persons work on the vast herds of cattle in the plains of La Plata{399}, and the other on a small stock of 20 or 30 animals in an island. The latter might have to wait centuries (by the hypothesis of no importance){400} before he obtained a "sport" approaching to what he wanted; but when he did and saved the greater number of its offspring and their offspring again, he might hope that his whole little stock would be in some degree affected, so that by continued selection he might gain his end. But on the Pampas, though the man might get his first approach to his desired form sooner, how hopeless would it be to attempt, by saving its offspring amongst so many of the common kind, to affect the whole herd: the effect of this one peculiar "sport{401}" would be quite lost before he could obtain a second original sport of the same kind. If, however, he could separate a small number of cattle, including the offspring of the desirable "sport," he might hope, like the man on the island, to effect his end. If there be organic beings of which two individuals _never_ unite, then simple selection whether on a continent or island would be equally serviceable to make a new and desirable breed; and this new breed might be made in surprisingly few years from the great and geometrical powers of propagation to beat out the old breed; as has happened (notwithstanding crossing) where good breeds of dogs and pigs have been introduced into a limited country,--for instance, into the islands of the Pacific. {399} This instance occurs in the Essay of 1842, p. 32, but not in the _Origin_; though the importance of isolation is discussed (_Origin_, Ed. i. p. 104, vi. p. 127). {400} The meaning of the words within parenthesis is obscure. {401} It is unusual to find the author speaking of the selection of _sports_ rather than small variations. Let us now take the simplest natural case of an islet upheaved by the volcanic or subterranean forces in a deep sea, at such a distance from other land that only a few organic beings at rare intervals were transported to it, whether borne by the sea{402} (like the seeds of plants to coral-reefs), or by hurricanes, or by floods, or on rafts, or in roots of large trees, or the germs of one plant or animal attached to or in the stomach of some other animal, or by the intervention (in most cases the most probable means) of other islands since sunk or destroyed. It may be remarked that when one part of the earth's crust is raised it is probably the general rule that another part sinks. Let this island go on slowly, century after century, rising foot by foot; and in the course of time we shall have instead <of> a small mass of rock{403}, lowland and highland, moist woods and dry sandy spots, various soils, marshes, streams and pools: under water on the sea shore, instead of a rocky steeply shelving coast, we shall have in some parts bays with mud, sandy beaches and rocky shoals. The formation of the island by itself must often slightly affect the surrounding climate. It is impossible that the first few transported organisms could be perfectly adapted to all these stations; and it will be a chance if those successively transported will be so adapted. The greater number would probably come from the lowlands of the nearest country; and not even all these would be perfectly adapted to the new islet whilst it continued low and exposed to coast influences. Moreover, as it is certain that all organisms are nearly as much adapted in their structure to the other inhabitants of their country as they are to its physical conditions, so the mere fact that a _few_ beings (and these taken in great degree by chance) were in the first case transported to the islet, would in itself greatly modify their conditions{404}. As the island continued rising we might also expect an occasional new visitant; and I repeat that even one new being must often affect beyond our calculation by occupying the room and taking part of the subsistence of another (and this again from another and so on), several or many other organisms. Now as the first transported and any occasional successive visitants spread or tended to spread over the growing island, they would undoubtedly be exposed through several generations to new and varying conditions: it might also easily happen that some of the species _on an average_ might obtain an increase of food, or food of a more nourishing quality{405}. According then to every analogy with what we have seen takes place in every country, with nearly every organic being under domestication, we might expect that some of the inhabitants of the island would "sport," or have their organization rendered in some degree plastic. As the number of the inhabitants are supposed to be few and as all these cannot be so well adapted to their new and varying conditions as they were in their native country and habitat, we cannot believe that every place or office in the economy of the island would be as well filled as on a continent where the number of aboriginal species is far greater and where they consequently hold a more strictly limited place. We might therefore expect on our island that although very many slight variations were of no use to the plastic individuals, yet that occasionally in the course of a century an individual might be born{406} of which the structure or constitution in some slight degree would allow it better to fill up some office in the insular economy and to struggle against other species. If such were the case the individual and its offspring would have a better _chance_ of surviving and of beating out its parent form; and if (as is probable) it and its offspring crossed with the unvaried parent form, yet the number of the individuals being not very great, there would be a chance of the new and more serviceable form being nevertheless in some slight degree preserved. The struggle for existence would go on annually selecting such individuals until a new race or species was formed. Either few or all the first visitants to the island might become modified, according as the physical conditions of the island and those resulting from the kind and number of other transported species were different from those of the parent country--according to the difficulties offered to fresh immigration--and according to the length of time since the first inhabitants were introduced. It is obvious that whatever was the country, generally the nearest from which the first tenants were transported, they would show an affinity, even if all had become modified, to the natives of that country and even if the inhabitants of the same source (?) had been modified. On this view we can at once understand the cause and meaning of the affinity of the fauna and flora of the Galapagos Islands with that of the coast of S. America; and consequently why the inhabitants of these islands show not the smallest affinity with those inhabiting other volcanic islands, with a very similar climate and soil, near the coast of Africa{407}. {402} This brief discussion is represented in the _Origin_, Ed. i. by a much fuller one (pp. 356, 383, vi. pp. 504, 535). See, however, the section in the present Essay, p. 168. {403} On the formation of new stations, see _Origin_, Ed. i. p. 292, vi. p. 429. {404} _Origin_, Ed. i. pp. 390, 400, vi. pp. 543, 554. {405} In the MS. _some of the species ... nourishing quality_ is doubtfully erased. It seems clear that he doubted whether such a problematical supply of food would be likely to cause variation. {406} At this time the author clearly put more faith in the importance of sport-like variation than in later years. {407} _Origin_, Ed. i. p. 398, vi. p. 553. To return once again to our island, if by the continued action of the subterranean forces other neighbouring islands were formed, these would generally be stocked by the inhabitants of the first island, or by a few immigrants from the neighbouring mainland; but if considerable obstacles were interposed to any communication between the terrestrial productions of these islands, and their conditions were different (perhaps only by the number of different species on each island), a form transported from one island to another might become altered in the same manner as one from the continent; and we should have several of the islands tenanted by representative races or species, as is so wonderfully the case with the different islands of the Galapagos Archipelago. As the islands become mountainous, if mountain-species were not introduced, as could rarely happen, a greater amount of variation and selection would be requisite to adapt the species, which originally came from the lowlands of the nearest continent, to the mountain-summits than to the lower districts of our islands. For the lowland species from the continent would have first to struggle against other species and other conditions on the coast-land of the island, and so probably become modified by the selection of its best fitted varieties, then to undergo the same process when the land had attained a moderate elevation; and then lastly when it had become Alpine. Hence we can understand why the faunas of insular mountain-summits are, as in the case of Teneriffe, eminently peculiar. Putting on one side the case of a widely extended flora being driven up the mountain-summits, during a change of climate from cold to temperate, we can see why in other cases the floras of mountain-summits (or as I have called them islands in a sea of land) should be tenanted by peculiar species, but related to those of the surrounding lowlands, as are the inhabitants of a real island in the sea to those of the nearest continent{408}. {408} See _Origin_, Ed. i. p. 403, vi. p. 558, where the author speaks of Alpine humming birds, rodents, plants, &c. in S. America, all of strictly American forms. In the MS. the author has added between the lines "As world has been getting hotter, there has been radiation from high-lands,--old view?--curious; I presume Diluvian in origin." Let us now consider the effect of a change of climate or of other conditions on the inhabitants of a continent and of an isolated island without any great change of level. On a continent the chief effects would be changes in the numerical proportion of the individuals of the different species; for whether the climate became warmer or colder, drier or damper, more uniform or extreme, some species are at present adapted to its diversified districts; if for instance it became cooler, species would migrate from its more temperate parts and from its higher land; if damper, from its damper regions, &c. On a small and isolated island, however, with few species, and these not adapted to much diversified conditions, such changes instead of merely increasing the number of certain species already adapted to such conditions, and decreasing the number of other species, would be apt to affect the constitutions of some of the insular species: thus if the island became damper it might well happen that there were no species living in any part of it adapted to the consequences resulting from more moisture. In this case therefore, and still more (as we have seen) during the production of new stations from the elevation of the land, an island would be a far more fertile source, as far as we can judge, of new specific forms than a continent. The new forms thus generated on an island, we might expect, would occasionally be transported by accident, or through long-continued geographical changes be enabled to emigrate and thus become slowly diffused. But if we look to the origin of a continent; almost every geologist will admit that in most cases it will have first existed as separate islands which gradually increased in size{409}; and therefore all that which has been said concerning the probable changes of the forms tenanting a small archipelago is applicable to a continent in its early state. Furthermore, a geologist who reflects on the geological history of Europe (the only region well known) will admit that it has been many times depressed, raised and left stationary. During the sinking of a continent and the probable generally accompanying changes of climate the effect would be little, _except_ on the numerical proportions and in the extinction (from the lessening of rivers, the drying of marshes and the conversion of high-lands into low &c.) of some or of many of the species. As soon however as the continent became divided into many isolated portions or islands, preventing free immigration from one part to another, the effect of climatic and other changes on the species would be greater. But let the now broken continent, forming isolated islands, begin to rise and new stations thus to be formed, exactly as in the first case of the upheaved volcanic islet, and we shall have equally favourable conditions for the modification of old forms, that is the formation of new races or species. Let the islands become reunited into a continent; and then the new and old forms would all spread, as far as barriers, the means of transportal, and the preoccupation of the land by other species, would permit. Some of the new species or races would probably become extinct, and some perhaps would cross and blend together. We should thus have a multitude of forms, adapted to all kinds of slightly different stations, and to diverse groups of either antagonist or food-serving species. The oftener these oscillations of level had taken place (and therefore generally the older the land) the greater the number of species <which> would tend to be formed. The inhabitants of a continent being thus derived in the first stage from the same original parents, and subsequently from the inhabitants of one wide area, since often broken up and reunited, all would be obviously related together and the inhabitants of the most _dissimilar_ stations on the same continent would be more closely allied than the inhabitants of two very _similar_ stations on two of the main divisions of the world{410}. {409} See the comparison between the Malay Archipelago and the probable former state of Europe, _Origin_, Ed. i. p. 299, vi. p. 438, also _Origin_, Ed. i. p. 292, vi. p. 429. {410} _Origin_, Ed. i. p. 349, vi. p. 496. The arrangement of the argument in the present Essay leads to repetition of statements made in the earlier part of the book: in the _Origin_ this is avoided. I need hardly point out that we now can obviously see why the number of species in two districts, independently of the number of stations in such districts, should be in some cases as widely different as in New Zealand and the Cape of Good Hope{411}. We can see, knowing the difficulty in the transport of terrestrial mammals, why islands far from mainlands do not possess them{412}; we see the general reason, namely accidental transport (though not the precise reason), why certain islands should, and others should not, possess members of the class of reptiles. We can see why an ancient channel of communication between two distant points, as the Cordillera probably was between southern Chile and the United States during the former cold periods; and icebergs between the Falkland Islands and Tierra del Fuego; and gales, at a former or present time, between the Asiatic shores of the Pacific and eastern islands in this ocean; is connected with (or we may now say causes) an affinity between the species, though distinct, in two such districts. We can see how the better chance of diffusion, from several of the species of any genus having wide ranges in their own countries, explains the presence of other species of the same genus in other countries{413}; and on the other hand, of species of restricted powers of ranging, forming genera with restricted ranges. {411} _Origin_, Ed. i. p. 389, vi. p. 542. {412} _Origin_, Ed. i. p. 393, vi. p. 547. {413} _Origin_, Ed. i. pp. 350, 404, vi. pp. 498, 559. As every one would be surprised if two exactly similar but peculiar varieties{414} of any species were raised by man by long continued selection, in two different countries, or at two very different periods, so we ought not to expect that an exactly similar form would be produced from the modification of an old one in two distinct countries or at two distinct periods. For in such places and times they would probably be exposed to somewhat different climates and almost certainly to different associates. Hence we can see why each species appears to have been produced singly, in space and in time. I need hardly remark that, according to this theory of descent, there is no necessity of modification in a species, when it reaches a new and isolated country. If it be able to survive and if slight variations better adapted to the new conditions are not selected, it might retain (as far as we can see) its old form for an indefinite time. As we see that some sub-varieties produced under domestication are more variable than others, so in nature, perhaps, some species and genera are more variable than others. The same precise form, however, would probably be seldom preserved through successive geological periods, or in widely and differently conditioned countries{415}. {414} _Origin_, Ed. i. p. 352, vi. p. 500. {415} _Origin_, Ed. i. p. 313, vi. p. 454. Finally, during the long periods of time and probably of oscillations of level, necessary for the formation of a continent, we may conclude (as above explained) that many forms would become extinct. These extinct forms, and those surviving (whether or not modified and changed in structure), will all be related in each continent in the same manner and degree, as are the inhabitants of any two different sub-regions in that same continent. I do not mean to say that, for instance, the present Marsupials of Australia or Edentata and rodents of S. America have descended from any one of the few fossils of the same orders which have been discovered in these countries. It is possible that, in a very few instances, this may be the case; but generally they must be considered as merely codescendants of common stocks{416}. I believe in this, from the improbability, considering the vast number of species, which (as explained in the last chapter) must by our theory have existed, that the _comparatively_ few fossils which have been found should chance to be the immediate and linear progenitors of those now existing. Recent as the yet discovered fossil mammifers of S. America are, who will pretend to say that very many intermediate forms may not have existed? Moreover, we shall see in the ensuing chapter that the very existence of genera and species can be explained only by a few species of each epoch leaving modified successors or new species to a future period; and the more distant that future period, the fewer will be the _linear_ heirs of the former epoch. As by our theory, all mammifers must have descended from the same parent stock, so is it necessary that each land now possessing terrestrial mammifers shall at some time have been so far united to other land as to permit the passage of mammifers{417}; and it accords with this necessity, that in looking far back into the earth's history we find, first changes in the geographical distribution, and secondly a period when the mammiferous forms most distinctive of two of the present main divisions of the world were living together{418}. {416} _Origin_, Ed. i. p. 341, vi. p. 487. {417} _Origin_, Ed. i. p. 396, vi. p. 549. {418} _Origin_, Ed. i. p. 340, vi. p. 486. I think then I am justified in asserting that most of the above enumerated and often trivial points in the geographical distribution of past and present organisms (which points must be viewed by the creationists as so many ultimate facts) follow as a simple consequence of specific forms being mutable and of their being adapted by natural selection to diverse ends, conjoined with their powers of dispersal, and the geologico-geographical changes now in slow progress and which undoubtedly have taken place. This large class of facts being thus explained, far more than counterbalances many separate difficulties and apparent objections in convincing my mind of the truth of this theory of common descent. _Improbability of finding fossil forms intermediate between existing species._ There is one observation of considerable importance that may be here introduced, with regard to the improbability of the chief transitional forms between any two species being found fossil. With respect to the finer shades of transition, I have before remarked that no one has any cause to expect to trace them in a fossil state, without he be bold enough to imagine that geologists at a future epoch will be able to trace from fossil bones the gradations between the Short-Horns, Herefordshire, and Alderney breeds of cattle{419}. I have attempted to show that rising islands, in process of formation, must be the best nurseries of new specific forms, and these points are the least favourable for the embedment of fossils{420}: I appeal, as evidence, to the state of the _numerous_ scattered islands in the several great oceans: how rarely do any sedimentary deposits occur on them; and when present they are mere narrow fringes of no great antiquity, which the sea is generally wearing away and destroying. The cause of this lies in isolated islands being generally volcanic and rising points; and the effects of subterranean elevation is to bring up the surrounding newly-deposited strata within the destroying action of the coast-waves: the strata, deposited at greater distances, and therefore in the depths of the ocean, will be almost barren of organic remains. These remarks may be generalised:--periods of subsidence will always be most favourable to an accumulation of great thicknesses of strata, and consequently to their long preservation; for without one formation be protected by successive strata, it will seldom be preserved to a distant age, owing to the enormous amount of denudation, which seems to be a general contingent of time{421}. I may refer, as evidence of this remark, to the vast amount of subsidence evident in the great pile of the European formations, from the Silurian epoch to the end of the Secondary, and perhaps to even a later period. Periods of elevation on the other hand cannot be favourable to the accumulation of strata and their preservation to distant ages, from the circumstance just alluded to, viz. of elevation tending to bring to the surface the circum-littoral strata (always abounding most in fossils) and destroying them. The bottom of tracts of deep water (little favourable, however, to life) must be excepted from this unfavourable influence of elevation. In the quite open ocean, probably no sediment{422} is accumulating, or at a rate so slow as not to preserve fossil remains, which will always be subject to disintegration. Caverns, no doubt, will be equally likely to preserve terrestrial fossils in periods of elevation and of subsidence; but whether it be owing to the enormous amount of denudation, which all land seems to have undergone, no cavern with fossil bones has been found belonging to the Secondary period{423}. {419} _Origin_, Ed. i. p. 299, vi. p. 437. {420} "Nature may almost be said to have guarded against the frequent discovery of her transitional or linking forms," _Origin_, Ed. i. p. 292. A similar but not identical passage occurs in _Origin_, Ed. vi. p. 428. {421} _Origin_, Ed. i. p. 291, vi. p. 426. {422} _Origin_, Ed. i. p. 288, vi. p. 422. {423} _Origin_, Ed. i. p. 289, vi. p. 423. Hence many more remains will be preserved to a distant age, in any region of the world, during periods of its subsidence{424}, than of its elevation. {424} _Origin_, Ed. i. p. 300, vi. p. 439. But during the subsidence of a tract of land, its inhabitants (as before shown) will from the decrease of space and of the diversity of its stations, and from the land being fully preoccupied by species fitted to diversified means of subsistence, be little liable to modification from selection, although many may, or rather must, become extinct. With respect to its circum-marine inhabitants, although during a change from a continent to a _great_ archipelago, the number of stations fitted for marine beings will be increased, their means of diffusion (an important check to change of form) will be greatly improved; for a continent stretching north and south, or a quite open space of ocean, seems to be to them the only barrier. On the other hand, during the elevation of a small archipelago and its conversion into a continent, we have, whilst the number of stations are increasing, both for aquatic and terrestrial productions, and whilst these stations are not fully preoccupied by perfectly adapted species, the most favourable conditions for the selection of new specific forms; but few of them in their early transitional states will be preserved to a distant epoch. We must wait during an enormous lapse of time, until long-continued subsidence shall have taken the place in this quarter of the world of the elevatory process, for the best conditions of the embedment and the preservation of its inhabitants. Generally the great mass of the strata in every country, from having been chiefly accumulated during subsidence, will be the tomb, not of transitional forms, but of those either becoming extinct or remaining unmodified. The state of our knowledge, and the slowness of the changes of level, do not permit us to test the truth of these remarks, by observing whether there are more transitional or "fine" (as naturalists would term them) species, on a rising and enlarging tract of land, than on an area of subsidence. Nor do I know whether there are more "fine" species on isolated volcanic islands in process of formation, than on a continent; but I may remark, that at the Galapagos Archipelago the number of forms, which according to some naturalists are true species, and according to others are mere races, is considerable: this particularly applies to the different species or races of the same genera inhabiting the different islands of this archipelago. Furthermore it may be added (as bearing on the great facts discussed in this chapter) that when naturalists confine their attention to any one country, they have comparatively little difficulty in determining what forms to call species and what to call varieties; that is, those which can or cannot be traced or shown to be probably descendants of some other form: but the difficulty increases, as species are brought from many stations, countries and islands. It was this increasing (but I believe in few cases insuperable) difficulty which seems chiefly to have urged Lamarck to the conclusion that species are mutable. CHAPTER VII ON THE NATURE OF THE AFFINITIES AND CLASSIFICATION OF ORGANIC BEINGS{425} {425} Ch. XIII of the _Origin_, Ed. i., Ch. XIV Ed. vi. begins with a similar statement. In the present Essay the author adds a note:--"The obviousness of the fact (_i.e._ the natural grouping of organisms) alone prevents it being remarkable. It is scarcely explicable by creationist: groups of aquatic, of vegetable feeders and carnivorous, &c., might resemble each other; but why as it is. So with plants,--analogical resemblance thus accounted for. Must not here enter into details." This argument is incorporated with the text in the _Origin_, Ed. i. _Gradual appearance and disappearance of groups._ It has been observed from the earliest times that organic beings fall into groups{426}, and these groups into others of several values, such as species into genera, and then into sub-families, into families, orders, &c. The same fact holds with those beings which no longer exist. Groups of species seem to follow the same laws in their appearance and extinction{427}, as do the individuals of any one species: we have reason to believe that, first, a few species appear, that their numbers increase; and that, when tending to extinction, the numbers of the species decrease, till finally the group becomes extinct, in the same way as a species becomes extinct, by the individuals becoming rarer and rarer. Moreover, groups, like the individuals of a species, appear to become extinct at different times in different countries. The Palæotherium was extinct much sooner in Europe than in India: the Trigonia{428} was extinct in early ages in Europe, but now lives in the seas of Australia. As it happens that one species of a family will endure for a much longer period than another species, so we find that some whole groups, such as Mollusca, tend to retain their forms, or to remain persistent, for longer periods than other groups, for instance than the Mammalia. Groups therefore, in their appearance, extinction, and rate of change or succession, seem to follow nearly the same laws with the individuals of a species{429}. {426} _Origin_, Ed. i. p. 411, vi. p. 566. {427} _Origin_, Ed. i. p. 316, vi. p. 457. {428} _Origin_, Ed. i. p. 321, vi. p. 463. {429} In the _Origin_, Ed. i. this preliminary matter is replaced (pp. 411, 412, vi. pp. 566, 567) by a discussion in which extinction is also treated, but chiefly from the point of view of the theory of divergence. _What is the Natural System?_ The proper arrangement of species into groups, according to the natural system, is the object of all naturalists; but scarcely two naturalists will give the same answer to the question, What is the natural system and how are we to recognise it? The most important characters{430} it might be thought (as it was by the earliest classifiers) ought to be drawn from those parts of the structure which determine its habits and place in the economy of nature, which we may call the final end of its existence. But nothing is further from the truth than this; how much external resemblance there is between the little otter (Chironectes) of Guiana and the common otter; or again between the common swallow and the swift; and who can doubt that the means and ends of their existence are closely similar, yet how grossly wrong would be the classification, which put close to each other a Marsupial and Placental animal, and two birds with widely different skeletons. Relations, such as in the two latter cases, or as that between the whale and fishes, are denominated "analogical{431}," or are sometimes described as "relations of adaption." They are infinitely numerous and often very singular; but are of no use in the classification of the higher groups. How it comes, that certain parts of the structure, by which the habits and functions of the species are settled, are of no use in classification, whilst other parts, formed at the same time, are of the greatest, it would be difficult to say, on the theory of separate creations. {430} _Origin_, Ed. i. p. 414, vi. p. 570. {431} _Origin_, Ed. i. p. 414, vi. p. 570. Some authors as Lamarck, Whewell &c., believe that the degree of affinity on the natural system depends on the degrees of resemblance in organs more or less physiologically important for the preservation of life. This scale of importance in the organs is admitted to be of difficult discovery. But quite independent of this, the proposition, as a general rule, must be rejected as false; though it may be partially true. For it is universally admitted that the same part or organ, which is of the highest service in classification in one group, is of very little use in another group, though in both groups, as far as we can see, the part or organ is of equal physiological importance: moreover, characters quite unimportant physiologically, such as whether the covering of the body consists of hair or feathers, whether the nostrils communicated with the mouth{432} &c., &c., are of the highest generality in classification; even colour, which is so inconstant in many species, will sometimes well characterise even a whole group of species. Lastly, the fact, that no one character is of so much importance in determining to what great group an organism belongs, as the forms through which the embryo{433} passes from the germ upwards to maturity, cannot be reconciled with the idea that natural classification follows according to the degrees of resemblance in the parts of most physiological importance. The affinity of the common rock-barnacle with the Crustaceans can hardly be perceived in more than a single character in its mature state, but whilst young, locomotive, and furnished with eyes, its affinity cannot be mistaken{434}. The cause of the greater value of characters, drawn from the early stages of life, can, as we shall in a succeeding chapter see, be in a considerable degree explained, on the theory of descent, although inexplicable on the views of the creationist. {432} These instances occur with others in the _Origin_, Ed. i. p. 416, vi. p. 572. {433} _Origin_, Ed. i. p. 418, vi. p. 574. {434} _Origin_, Ed. i. pp. 419, 440, vi. pp. 575, 606. Practically, naturalists seem to classify according to the resemblance of those parts or organs which in related groups are most uniform, or vary least{435}: thus the æstivation, or manner in which the petals etc. are folded over each other, is found to afford an unvarying character in most families of plants, and accordingly any difference in this respect would be sufficient to cause the rejection of a species from many families; but in the Rubiaceæ the æstivation is a varying character, and a botanist would not lay much stress on it, in deciding whether or not to class a new species in this family. But this rule is obviously so arbitrary a formula, that most naturalists seem to be convinced that something ulterior is represented by the natural system; they appear to think that we only discover by such similarities what the arrangement of the system is, not that such similarities make the system. We can only thus understand Linnæus'{436} well-known saying, that the characters do not make the genus; but that the genus gives the characters: for a classification, independent of characters, is here presupposed. Hence many naturalists have said that the natural system reveals the plan of the Creator: but without it be specified whether order in time or place, or what else is meant by the plan of the Creator, such expressions appear to me to leave the question exactly where it was. {435} _Origin_, Ed. i. pp. 418, 425, vi. pp. 574, 581. {436} _Origin_, Ed. i. p. 413, vi. p. 569. Some naturalists consider that the geographical position{437} of a species may enter into the consideration of the group into which it should be placed; and most naturalists (either tacitly or openly) give value to the different groups, not solely by their relative differences in structure, but by the number of forms included in them. Thus a genus containing a few species might be, and has often been, raised into a family on the discovery of several other species. Many natural families are retained, although most closely related to other families, from including a great number of closely similar species. The more logical naturalist would perhaps, if he could, reject these two contingents in classification. From these circumstances, and especially from the undefined objects and criterions of the natural system, the number of divisions, such as genera, sub-families, families, &c., &c., has been quite arbitrary{438}; without the clearest definition, how can it be possible to decide whether two groups of species are of equal value, and of what value? whether they should both be called genera or families; or whether one should be a genus, and the other a family{439}? {437} _Origin_, Ed. i. pp. 419, 427, vi. pp. 575, 582. {438} This is discussed from the point of view of divergence in the _Origin_, Ed. i. pp. 420, 421, vi. pp. 576, 577. {439} <Footnote by the author.> I discuss this because if Quinarism true, I false. <The Quinary System is set forth in W. S. Macleay's _Horæ Entomologicæ_, 1821.> _On the kind of relation between distinct groups._ I have only one other remark on the affinities of organic beings; that is, when two quite distinct groups approach each other, the approach is _generally_ generic{440} and not special; I can explain this most easily by an example: of all Rodents the Bizcacha, by certain peculiarities in its reproductive system, approaches nearest to the Marsupials; of all Marsupials the Phascolomys, on the other hand, appears to approach in the form of its teeth and intestines nearest to the Rodents; but there is no special relation between these two genera{441}; the Bizcacha is no nearer related to the Phascolomys than to any other Marsupial in the points in which it approaches this division; nor again is the Phascolomys, in the points of structure in which it approaches the Rodents, any nearer related to the Bizcacha than to any other Rodent. Other examples might have been chosen, but I have given (from Waterhouse) this example as it illustrates another point, namely, the difficulty of determining what are analogical or adaptive and what real affinities; it seems that the teeth of the Phascolomys though _appearing closely_ to resemble those of a Rodent are found to be built on the Marsupial type; and it is thought that these teeth and consequently the intestines may have been adapted to the peculiar life of this animal and therefore may not show any real relation. The structure in the Bizcacha that connects it with the Marsupials does not seem a peculiarity related to its manner of life, and I imagine that no one would doubt that this shows a real affinity, though not more with any one Marsupial species than with another. The difficulty of determining what relations are real and what analogical is far from surprising when no one pretends to define the meaning of the term relation or the ulterior object of all classification. We shall immediately see on the theory of descent how it comes that there should be "real" and "analogical" affinities; and why the former alone should be of value in classification--difficulties which it would be I believe impossible to explain on the ordinary theory of separate creations. {440} In the corresponding passage in the _Origin_, Ed. i. p. 430, vi. p. 591, the term _general_ is used in place of _generic_, and seems a better expression. In the margin the author gives Waterhouse as his authority. {441} _Origin_, Ed. i. p. 430, vi. p. 591. _Classification of Races or Varieties._ Let us now for a few moments turn to the classification of the generally acknowledged varieties and subdivisions of our domestic beings{442}; we shall find them systematically arranged in groups of higher and higher value. De Candolle has treated the varieties of the cabbage exactly as he would have done a natural family with various divisions and subdivisions. In dogs again we have one main division which may be called the _family_ of hounds; of these, there are several (we will call them) _genera_, such as blood-hounds, fox-hounds, and harriers; and of each of these we have different _species_, as the blood-hound of Cuba and that of England; and of the latter again we have breeds truly producing their own kind, which may be called races or varieties. Here we see a classification practically used which typifies on a lesser scale that which holds good in nature. But amongst true species in the natural system and amongst domestic races the number of divisions or groups, instituted between those most alike and those most unlike, seems to be quite arbitrary. The number of the forms in both cases seems practically, whether or not it ought theoretically, to influence the denomination of groups including them. In both, geographical distribution has sometimes been used as an aid to classification{443}; amongst varieties, I may instance, the cattle of India or the sheep of Siberia, which from possessing some characters in common permit a classification of Indian and European cattle, or Siberian and European sheep. Amongst domestic varieties we have even something very like the relations of "analogy" or "adaptation{444}"; thus the common and Swedish turnip are both artificial varieties which strikingly resemble each other, and they fill nearly the same end in the economy of the farm-yard; but although the swede so much more resembles a turnip than its presumed parent the field cabbage, no one thinks of putting it out of the cabbages into the turnips. Thus the greyhound and racehorse, having been selected and trained for extreme fleetness for short distances, present an analogical resemblance of the same kind, but less striking as that between the little otter (Marsupial) of Guiana and the common otter; though these two otters are really less related than <are> the horse and dog. We are even cautioned by authors treating on varieties, to follow the _natural_ in contradistinction of an artificial system and not, for instance, to class two varieties of the pine-apple{445} near each other, because their fruits accidentally resemble each other closely (though the fruit may be called _the final end_ of this plant in the economy of its world, the hothouse), but to judge from the general resemblance of the entire plants. Lastly, varieties often become extinct; sometimes from unexplained causes, sometimes from accident, but more often from the production of more useful varieties, and the less useful ones being destroyed or bred out. {442} In a corresponding passage in the _Origin_, Ed. i. p. 423, vi. p. 579, the author makes use of his knowledge of pigeons. The pseudo-genera among dogs are discussed in _Var. under Dom._, Ed. ii. vol. I. p. 38. {443} _Origin_, Ed. i. pp. 419, 427, vi. pp. 575, 582. {444} _Origin_, Ed. i. pp. 423, 427, vi. pp. 579, 583. {445} _Origin_, Ed. i. p. 423, vi. p. 579. I think it cannot be doubted that the main cause of all the varieties which have descended from the aboriginal dog or dogs, or from the aboriginal wild cabbage, not being equally like or unlike--but on the contrary, obviously falling into groups and sub-groups--must in chief part be attributed to different degrees of true relationship; for instance, that the different kinds of blood-hound have descended from one stock, whilst the harriers have descended from another stock, and that both these have descended from a different stock from that which has been the parent of the several kinds of greyhound. We often hear of a florist having some choice variety and breeding from it a whole group of sub-varieties more or less characterised by the peculiarities of the parent. The case of the peach and nectarine, each with their many varieties, might have been introduced. No doubt the relationship of our different domestic breeds has been obscured in an extreme degree by their crossing; and likewise from the slight difference between many breeds it has probably often happened that a "sport" from one breed has less closely resembled its parent breed than some other breed, and has therefore been classed with the latter. Moreover the effects of a similar climate{446} may in some cases have more than counterbalanced the similarity, consequent on a common descent, though I should think the similarity of the breeds of cattle of India or sheep of Siberia was far more probably due to the community of their descent than to the effects of climate on animals descended from different stocks. {446} A general statement of the influence of conditions on variation occurs in the _Origin_, Ed. i. pp. 131-3, vi. pp. 164-5. Notwithstanding these great sources of difficulty, I apprehend every one would admit, that if it were possible, a genealogical classification of our domestic varieties would be the most satisfactory one; and as far as varieties were concerned would be the natural system: in some cases it has been followed. In attempting to follow out this object a person would have to class a variety, whose parentage he did not know, by its external characters; but he would have a distinct ulterior object in view, namely, its descent in the same manner as a regular systematist seems also to have an ulterior but undefined end in all his classifications. Like the regular systematist he would not care whether his characters were drawn from more or less important organs as long as he found in the tribe which he was examining that the characters from such parts were persistent; thus amongst cattle he does value a character drawn from the form of the horns more than from the proportions of the limbs and whole body, for he finds that the shape of the horns is to a considerable degree persistent amongst cattle{447}, whilst the bones of the limbs and body vary. No doubt as a frequent rule the more important the organ, as being less related to external influences, the less liable it is to variation; but he would expect that according to the object for which the races had been selected, parts more or less important might differ; so that characters drawn from parts generally most liable to vary, as colour, might in some instances be highly serviceable--as is the case. He would admit that general resemblances scarcely definable by language might sometimes serve to allocate a species by its nearest relation. He would be able to assign a clear reason why the close similarity of the fruit in two varieties of pine-apple, and of the so-called root in the common and Swedish turnips, and why the similar gracefulness of form in the greyhound and racehorse, are characters of little value in classification; namely, because they are the result, not of community of descent, but either of selection for a common end, or of the effects of similar external conditions. {447} _Origin_, Ed. i. p. 423, vi. p. 579. In the margin Marshall is given as the authority. _Classification of "races" and species similar._ Thus seeing that both the classifiers of species and of varieties{448} work by the same means, make similar distinctions in the value of the characters, and meet with similar difficulties, and that both seem to have in their classification an ulterior object in view; I cannot avoid strongly suspecting that the same cause, which has made amongst our domestic varieties groups and sub-groups, has made similar groups (but of higher values) amongst species; and that this cause is the greater or less propinquity of actual descent. The simple fact of species, both those long since extinct and those now living, being divisible into genera, families, orders &c.--divisions analogous to those into which varieties are divisible--is otherwise an inexplicable fact, and only not remarkable from its familiarity. {448} _Origin_, Ed. i. p. 423, vi. p. 579. _Origin of genera and families._ Let us suppose{449} for example that a species spreads and arrives at six or more different regions, or being already diffused over one wide area, let this area be divided into six distinct regions, exposed to different conditions, and with stations slightly different, not fully occupied with other species, so that six different races or species were formed by selection, each best fitted to its new habits and station. I must remark that in every case, if a species becomes modified in any one sub-region, it is probable that it will become modified in some other of the sub-regions over which it is diffused, for its organization is shown to be capable of being rendered plastic; its diffusion proves that it is able to struggle with the other inhabitants of the several sub-regions; and as the organic beings of every great region are in some degree allied, and as even the physical conditions are often in some respects alike, we might expect that a modification in structure, which gave our species some advantage over antagonist species in one sub-region, would be followed by other modifications in other of the sub-regions. The races or new species supposed to be formed would be closely related to each other; and would either form a new genus or sub-genus, or would rank (probably forming a slightly different section) in the genus to which the parent species belonged. In the course of ages, and during the contingent physical changes, it is probable that some of the six new species would be destroyed; but the same advantage, whatever it may have been (whether mere tendency to vary, or some peculiarity of organization, power of mind, or means of distribution), which in the parent-species and in its six selected and changed species-offspring, caused them to prevail over other antagonist species, would generally tend to preserve some or many of them for a long period. If then, two or three of the six species were preserved, they in their turn would, during continued changes, give rise to as many small groups of species: if the parents of these small groups were closely similar, the new species would form one great genus, barely perhaps divisible into two or three sections: but if the parents were considerably unlike, their species-offspring would, from inheriting most of the peculiarities of their parent-stocks, form either two or more sub-genera or (if the course of selection tended in different ways) genera. And lastly species descending from different species of the newly formed genera would form new genera, and such genera collectively would form a family. {449} The discussion here following corresponds more or less to the _Origin_, Ed. i. pp. 411, 412, vi. pp. 566, 567; although the doctrine of divergence is not mentioned in this Essay (as it is in the _Origin_) yet the present section seems to me a distinct approximation to it. The extermination of species follows from changes in the external conditions, and from the increase or immigration of more favoured species: and as those species which are undergoing modification in any one great region (or indeed over the world) will very often be allied ones from (as just explained) partaking of many characters, and therefore advantages in common, so the species, whose place the new or more favoured ones are seizing, from partaking of a common inferiority (whether in any particular point of structure, or of general powers of mind, of means of distribution, of capacity for variation, &c., &c.), will be apt to be allied. Consequently species of the same genus will slowly, one after the other, _tend_ to become rarer and rarer in numbers, and finally extinct; and as each last species of several allied genera fails, even the family will become extinct. There may of course be occasional exceptions to the entire destruction of any genus or family. From what has gone before, we have seen that the slow and successive formation of several new species from the same stock will make a new genus, and the slow and successive formation of several other new species from another stock will make another genus; and if these two stocks were allied, such genera will make a new family. Now, as far as our knowledge serves, it is in this slow and gradual manner that groups of species appear on, and disappear from, the face of the earth. The manner in which, according to our theory, the arrangement of species in groups is due to partial extinction, will perhaps be rendered clearer in the following way. Let us suppose in any one great class, for instance in the Mammalia, that every species and every variety, during each successive age, had sent down one unaltered descendant (either fossil or living) to the present time; we should then have had one enormous series, including by small gradations every known mammiferous form; and consequently the existence of groups{450}, or chasms in the series, which in some parts are in greater width, and in some of less, is solely due to former species, and whole groups of species, not having thus sent down descendants to the present time. {450} The author probably intended to write "groups separated by chasms." With respect to the "analogical" or "adaptive" resemblances between organic beings which are not really related{451}, I will only add, that probably the isolation of different groups of species is an important element in the production of such characters: thus we can easily see, in a large increasing island, or even a continent like Australia, stocked with only certain orders of the main classes, that the conditions would be highly favourable for species from these orders to become adapted to play parts in the economy of nature, which in other countries were performed by tribes especially adapted to such parts. We can understand how it might happen that an otter-like animal might have been formed in Australia by slow selection from the more carnivorous Marsupial types; thus we can understand that curious case in the southern hemisphere, where there are no auks (but many petrels), of a petrel{452} having been modified into the external general form so as to play the same office in nature with the auks of the northern hemisphere; although the habits and form of the petrels and auks are normally so wholly different. It follows, from our theory, that two orders must have descended from one common stock at an immensely remote epoch; and we can perceive when a species in either order, or in both, shows some affinity to the other order, why the affinity is usually generic and not particular--that is why the Bizcacha amongst Rodents, in the points in which it is related to the Marsupial, is related to the whole group{453}, and not particularly to the Phascolomys, which of all Marsupialia is related most to the Rodents. For the Bizcacha is related to the present Marsupialia, only from being related to their common parent-stock; and not to any one species in particular. And generally, it may be observed in the writings of most naturalists, that when an organism is described as intermediate between two _great_ groups, its relations are not to particular species of either group, but to both groups, as wholes. A little reflection will show how exceptions (as that of the Lepidosiren, a fish closely related to _particular_ reptiles) might occur, namely from a few descendants of those species, which at a very early period branched out from a common parent-stock and so formed the two orders or groups, having survived, in nearly their original state, to the present time. {451} A similar discussion occurs in the _Origin_, Ed. i. p. 427, vi. p. 582. {452} _Puffinuria berardi_, see _Origin_, Ed. i. p. 184, vi. p. 221. {453} _Origin_, Ed. i. p. 430, vi. p. 591. Finally, then, we see that all the leading facts in the affinities and classification of organic beings can be explained on the theory of the natural system being simply a genealogical one. The similarity of the principles in classifying domestic varieties and true species, both those living and extinct, is at once explained; the rules followed and difficulties met with being the same. The existence of genera, families, orders, &c., and their mutual relations, naturally ensues from extinction going on at all periods amongst the diverging descendants of a common stock. These terms of affinity, relations, families, adaptive characters, &c., which naturalists cannot avoid using, though metaphorically, cease being so, and are full of plain signification. CHAPTER VIII UNITY OF TYPE IN THE GREAT CLASSES; AND MORPHOLOGICAL STRUCTURES _Unity of Type_{454}. {454} _Origin_, Ed. i. p. 434, vi. p. 595. Ch. VIII corresponds to a section of Ch. XIII in the _Origin_, Ed. i. Scarcely anything is more wonderful or has been oftener insisted on than that the organic beings in each great class, though living in the most distant climes and at periods immensely remote, though fitted to widely different ends in the economy of nature, yet all in their internal structure evince an obvious uniformity. What, for instance, is more wonderful than that the hand to clasp, the foot or hoof to walk, the bat's wing to fly, the porpoise's fin{455} to swim, should all be built on the same plan? and that the bones in their position and number should be so similar that they can all be classed and called by the same names. Occasionally some of the bones are merely represented by an apparently useless, smooth style, or are soldered closely to other bones, but the unity of type is not by this destroyed, and hardly rendered less clear. We see in this fact some deep bond of union between the organic beings of the same great classes--to illustrate which is the object and foundation of the natural system. The perception of this bond, I may add, is the evident cause that naturalists make an ill-defined distinction between true and adaptive affinities. {455} _Origin_, Ed. i. p. 434, vi. p. 596. In the _Origin_, Ed. i. these examples occur under the heading _Morphology_; the author does not there draw much distinction between this heading and that of _Unity of Type_. _Morphology._ There is another allied or rather almost identical class of facts admitted by the least visionary naturalists and included under the name of Morphology. These facts show that in an individual organic being, several of its organs consist of some other organ metamorphosed{456}: thus the sepals, petals, stamens, pistils, &c. of every plant can be shown to be metamorphosed leaves; and thus not only can the number, position and transitional states of these several organs, but likewise their monstrous changes, be most lucidly explained. It is believed that the same laws hold good with the gemmiferous vesicles of Zoophytes. In the same manner the number and position of the extraordinarily complicated jaws and palpi of Crustacea and of insects, and likewise their differences in the different groups, all become simple, on the view of these parts, or rather legs and all metamorphosed appendages, being metamorphosed legs. The skulls, again, of the Vertebrata are composed of three metamorphosed vertebræ, and thus we can see a meaning in the number and strange complication of the bony case of the brain. In this latter instance, and in that of the jaws of the Crustacea, it is only necessary to see a series taken from the different groups of each class to admit the truth of these views. It is evident that when in each species of a group its organs consist of some other part metamorphosed, that there must also be a "unity of type" in such a group. And in the cases as that above given in which the foot, hand, wing and paddle are said to be constructed on a uniform type, if we could perceive in such parts or organs traces of an apparent change from some other use or function, we should strictly include such parts or organs in the department of morphology: thus if we could trace in the limbs of the Vertebrata, as we can in their ribs, traces of an apparent change from being processes of the vertebræ, it would be said that in each species of the Vertebrata the limbs were "metamorphosed spinal processes," and that in all the species throughout the class the limbs displayed a "unity of type{457}." {456} See _Origin_, Ed. i. p. 436, vi. p. 599, where the parts of the flower, the jaws and palpi of Crustaceans and the vertebrate skull are given as examples. {457} The author here brings _Unity of Type_ and _Morphology_ together. These wonderful parts of the hoof, foot, hand, wing, paddle, both in living and extinct animals, being all constructed on the same framework, and again of the petals, stamina, germens, &c. being metamorphosed leaves, can by the creationist be viewed only as ultimate facts and incapable of explanation; whilst on our theory of descent these facts all necessary follow: for by this theory all the beings of any one class, say of the mammalia, are supposed to be descended from one parent-stock, and to have been altered by such slight steps as man effects by the selection of chance domestic variations. Now we can see according to this view that a foot might be selected with longer and longer bones, and wider connecting membranes, till it became a swimming organ, and so on till it became an organ by which to flap along the surface or to glide over it, and lastly to fly through the air: but in such changes there would be no tendency to alter the framework of the internal inherited structure. Parts might become lost (as the tail in dogs, or horns in cattle, or the pistils in plants), others might become united together (as in the feet of the Lincolnshire breed of pigs{458}, and in the stamens of many garden flowers); parts of a similar nature might become increased in number (as the vertebræ in the tails of pigs, &c., &c. and the fingers and toes in six-fingered races of men and in the Dorking fowls), but analogous differences are observed in nature and are not considered by naturalists to destroy the uniformity of the types. We can, however, conceive such changes to be carried to such length that the unity of type might be obscured and finally be undistinguishable, and the paddle of the Plesiosaurus has been advanced as an instance in which the uniformity of type can hardly be recognised{459}. If after long and gradual changes in the structure of the co-descendants from any parent stock, evidence (either from monstrosities or from a graduated series) could be still detected of the function, which certain parts or organs played in the parent stock, these parts or organs might be strictly determined by their former function with the term "metamorphosed" appended. Naturalists have used this term in the same metaphorical manner as they have been obliged to use the terms of affinity and relation; and when they affirm, for instance, that the jaws of a crab are metamorphosed legs, so that one crab has more legs and fewer jaws than another, they are far from meaning that the jaws, either during the life of the individual crab or of its progenitors, were really legs. By our theory this term assumes its literal meaning{460}; and this wonderful fact of the complex jaws of an animal retaining numerous characters, which they would probably have retained if they had really been metamorphosed during many successive generations from true legs, is simply explained. {458} The solid-hoofed pigs mentioned in _Var. under Dom._, Ed. ii. vol. II. p. 424 are not _Lincolnshire pigs_. For other cases see Bateson, _Materials for the Study of Variation_, 1894, pp. 387-90. {459} In the margin C. Bell is given as authority, apparently for the statement about Plesiosaurus. See _Origin_, Ed. i. p. 436, vi. p. 598, where the author speaks of the "general pattern" being obscured in "extinct gigantic sea lizards." In the same place the suctorial Entomostraca are added as examples of the difficulty of recognising the type. {460} _Origin_, Ed. i. p. 438, vi. p. 602. _Embryology_. The unity of type in the great classes is shown in another and very striking manner, namely, in the stages through which the embryo passes in coming to maturity{461}. Thus, for instance, at one period of the embryo, the wings of the bat, the hand, hoof or foot of the quadruped, and the fin of the porpoise do not differ, but consist of a simple undivided bone. At a still earlier period the embryo of the fish, bird, reptile and mammal all strikingly resemble each other. Let it not be supposed this resemblance is only external; for on dissection, the arteries are found to branch out and run in a peculiar course, wholly unlike that in the full-grown mammal and bird, but much less unlike that in the full-grown fish, for they run as if to ærate blood by branchiæ{462} on the neck, of which even the slit-like orifices can be discerned. How wonderful it is that this structure should be present in the embryos of animals about to be developed into such different forms, and of which two great classes respire only in the air. Moreover, as the embryo of the mammal is matured in the parent's body, and that of the bird in an egg in the air, and that of the fish in an egg in the water, we cannot believe that this course of the arteries is related to any external conditions. In all shell-fish (Gasteropods) the embryo passes through a state analogous to that of the Pteropodous Mollusca: amongst insects again, even the most different ones, as the moth, fly and beetle, the crawling larvæ are all closely analogous: amongst the Radiata, the jelly-fish in its embryonic state resembles a polype, and in a still earlier state an infusorial animalcule--as does likewise the embryo of the polype. From the part of the embryo of a mammal, at one period, resembling a fish more than its parent form; from the larvæ of all orders of insects more resembling the simpler articulate animals than their parent insects{463}; and from such other cases as the embryo of the jelly-fish resembling a polype much nearer than the perfect jelly-fish; it has often been asserted that the higher animal in each class passes through the state of a lower animal; for instance, that the mammal amongst the vertebrata passes through the state of a fish{464}: but Müller denies this, and affirms that the young mammal is at no time a fish, as does Owen assert that the embryonic jelly-fish is at no time a polype, but that mammal and fish, jelly-fish and polype pass through the same state; the mammal and jelly-fish being only further developed or changed. {461} _Origin_, Ed. i. p. 439, vi. p. 604. {462} The uselessness of the branchial arches in mammalia is insisted on in the _Origin_, Ed. i. p. 440, vi. p. 606. Also the uselessness of the spots on the young blackbird and the stripes of the lion-whelp, cases which do not occur in the present Essay. {463} In the _Origin_, Ed. i. pp. 442, 448, vi. pp. 608, 614 it is pointed out that in some cases the young form resembles the adult, _e.g._ in spiders; again, that in the Aphis there is no "worm-like stage" of development. {464} In the _Origin_, Ed. i. p. 449, vi. p. 618, the author speaks doubtfully about the recapitulation theory. As the embryo, in most cases, possesses a less complicated structure than that into which it is to be developed, it might have been thought that the resemblance of the embryo to less complicated forms in the same great class, was in some manner a necessary preparation for its higher development; but in fact the embryo, during its growth, may become less, as well as more, complicated{465}. Thus certain female Epizoic Crustaceans in their mature state have neither eyes nor any organs of locomotion; they consist of a mere sack, with a simple apparatus for digestion and procreation; and when once attached to the body of the fish, on which they prey, they never move again during their whole lives: in their embryonic condition, on the other hand, they are furnished with eyes, and with well articulated limbs, actively swim about and seek their proper object to become attached to. The larvæ, also, of some moths are as complicated and are more active than the wingless and limbless females, which never leave their pupa-case, never feed and never see the daylight. {465} This corresponds to the _Origin_, Ed. i. p. 441, vi. p. 607, where, however, the example is taken from the Cirripedes. _Attempt to explain the facts of embryology._ I think considerable light can be thrown by the theory of descent on these wonderful embryological facts which are common in a greater or less degree to the whole animal kingdom, and in some manner to the vegetable kingdom: on the fact, for instance, of the arteries in the embryonic mammal, bird, reptile and fish, running and branching in the same courses and nearly in the same manner with the arteries in the full-grown fish; on the fact I may add of the high importance to systematic naturalists{466} of the characters and resemblances in the embryonic state, in ascertaining the true position in the natural system of mature organic beings. The following are the considerations which throw light on these curious points. {466} _Origin_, Ed. i. p. 449, vi. p. 617. In the economy, we will say of a feline animal{467}, the feline structure of the embryo or of the sucking kitten is of quite secondary importance to it; hence, if a feline animal varied (assuming for the time the possibility of this) and if some place in the economy of nature favoured the selection of a longer-limbed variety, it would be quite unimportant to the production by natural selection of a long-limbed breed, whether the limbs of the embryo and kitten were elongated if they _became_ so _as soon_ as the animal had to provide food for itself. And if it were found after continued selection and the production of several new breeds from one parent-stock, that the successive variations had supervened, not very early in the youth or embryonic life of each breed (and we have just seen that it is quite unimportant whether it does so or not), then it obviously follows that the young or embryos of the several breeds will continue resembling each other more closely than their adult parents{468}. And again, if two of these breeds became each the parent-stock of several other breeds, forming two genera, the young and embryos of these would still retain a greater resemblance to the one original stock than when in an adult state. Therefore if it could be shown that the period of the slight successive variations does not always supervene at a very early period of life, the greater resemblance or closer unity in type of animals in the young than in the full-grown state would be explained. Before practically{469} endeavouring to discover in our domestic races whether the structure or form of the young has or has not changed in an exactly corresponding degree with the changes of full-grown animals, it will be well to show that it is at least quite _possible_ for the primary germinal vesicle to be impressed with a tendency to produce some change on the growing tissues which will not be fully effected till the animal is advanced in life. {467} This corresponds to the _Origin_, Ed. i. pp. 443-4, vi. p. 610: the "feline animal" is not used to illustrate the generalisation, but is so used in the Essay of 1842, p. 42. {468} _Origin_, Ed. i. p. 447, vi. p. 613. {469} In the margin is written "Get young pigeons"; this was afterwards done, and the results are given in the _Origin_, Ed. i. p. 445, vi. p. 612. From the following peculiarities of structure being inheritable and appearing only when the animal is full-grown--namely, general size, tallness (not consequent on the tallness of the infant), fatness either over the whole body, or local; change of colour in hair and its loss; deposition of bony matter on the legs of horses; blindness and deafness, that is changes of structure in the eye and ear; gout and consequent deposition of chalk-stones; and many other diseases{470}, as of the heart and brain, &c., &c.; from all such tendencies being I repeat inheritable, we clearly see that the germinal vesicle is impressed with some power which is wonderfully preserved during the production of infinitely numerous cells in the ever changing tissues, till the part ultimately to be affected is formed and the time of life arrived at. We see this clearly when we select cattle with any peculiarity of their horns, or poultry with any peculiarity of their second plumage, for such peculiarities cannot of course reappear till the animal is mature. Hence, it is certainly _possible_ that the germinal vesicle may be impressed with a tendency to produce a long-limbed animal, the full proportional length of whose limbs shall appear only when the animal is mature{471}. {470} In the _Origin_, Ed. i. the corresponding passages are at pp. 8, 13, 443, vi. pp. 8, 15, 610. In the _Origin_, Ed. i. I have not found a passage so striking as that which occurs a few lines lower "that the germinal vesicle is impressed with some power which is wonderfully preserved, &c." In the _Origin_ this _preservation_ is rather taken for granted. {471} <In the margin is written> Aborted organs show, perhaps, something about period <at> which changes supervene in embryo. In several of the cases just enumerated we know that the first cause of the peculiarity, when _not_ inherited, lies in the conditions to which the animal is exposed during mature life, thus to a certain extent general size and fatness, lameness in horses and in a lesser degree blindness, gout and some other diseases are certainly in some degree caused and accelerated by the habits of life, and these peculiarities when transmitted to the offspring of the affected person reappear at a nearly corresponding time of life. In medical works it is asserted generally that at whatever period an hereditary disease appears in the parent, it tends to reappear in the offspring at the same period. Again, we find that early maturity, the season of reproduction and longevity are transmitted to corresponding periods of life. Dr Holland has insisted much on children of the same family exhibiting certain diseases in similar and peculiar manners; my father has known three brothers{472} die in very old age in a _singular_ comatose state; now to make these latter cases strictly bear, the children of such families ought similarly to suffer at corresponding times of life; this is probably not the case, but such facts show that a tendency in a disease to appear at particular stages of life can be transmitted through the germinal vesicle to different individuals of the same family. It is then certainly possible that diseases affecting widely different periods of life can be transmitted. So little attention is paid to very young domestic animals that I do not know whether any case is on record of selected peculiarities in young animals, for instance, in the first plumage of birds, being transmitted to their young. If, however, we turn to silk-worms{473}, we find that the caterpillars and coccoons (which must correspond to a _very early_ period of the embryonic life of mammalia) vary, and that these varieties reappear in the offspring caterpillars and coccoons. {472} See p. 42, note 5.{Note 160} {473} The evidence is given in _Var. under Dom._, I. p. 316. I think these facts are sufficient to render it probable that at whatever period of life any peculiarity (capable of being inherited) appears, whether caused by the action of external influences during mature life, or from an affection of the primary germinal vesicle, it _tends_ to reappear in the offspring at the corresponding period of life{474}. Hence (I may add) whatever effect training, that is the full employment or action of every newly selected slight variation, has in fully developing and increasing such variation, would only show itself in mature age, corresponding to the period of training; in the second chapter I showed that there was in this respect a marked difference in natural and artificial selection, man not regularly exercising or adapting his varieties to new ends, whereas selection by nature presupposes such exercise and adaptation in each selected and changed part. The foregoing facts show and presuppose that slight variations occur at various periods of life _after birth_; the facts of monstrosity, on the other hand, show that many changes take place before birth, for instance, all such cases as extra fingers, hare-lip and all sudden and great alterations in structure; and these when inherited reappear during the embryonic period in the offspring. I will only add that at a period even anterior to embryonic life, namely, during the _egg_ state, varieties appear in size and colour (as with the Hertfordshire duck with blackish eggs{475}) which reappear in the egg; in plants also the capsule and membranes of the seed are very variable and inheritable. {474} _Origin_, Ed. i. p. 444, vi. p. 610. {475} In _Var. under Dom._, Ed. ii. vol. I. p. 295, such eggs are said to be laid early in each season by the black Labrador duck. In the next sentence in the text the author does not distinguish the characters of the vegetable capsule from those of the ovum. If then the two following propositions are admitted (and I think the first can hardly be doubted), viz. that variation of structure takes place at all times of life, though no doubt far less in amount and seldomer in quite mature life{476} (and then generally taking the form of disease); and secondly, that these variations tend to reappear at a corresponding period of life, which seems at least probable, then we might _a priori_ have expected that in any selected breed the _young_ animal would not partake in a corresponding degree the peculiarities characterising the _full-grown_ parent; though it would in a lesser degree. For during the thousand or ten thousand selections of slight increments in the length of the limbs of individuals necessary to produce a long-limbed breed, we might expect that such increments would take place in different individuals (as we do not certainly know at what period they do take place), some earlier and some later in the embryonic state, and some during early youth; and these increments would reappear in their offspring only at corresponding periods. Hence, the entire length of limb in the new long-limbed breed would only be acquired at the latest period of life, when that one which was latest of the thousand primary increments of length supervened. Consequently, the foetus of the new breed during the earlier part of its existence would remain much less changed in the proportions of its limbs; and the earlier the period the less would the change be. {476} This seems to me to be more strongly stated here than in the _Origin_, Ed. i. Whatever may be thought of the facts on which this reasoning is grounded, it shows how the embryos and young of different species might come to remain less changed than their mature parents; and practically we find that the young of our domestic animals, though differing, differ less than their full-grown parents. Thus if we look at the young puppies{477} of the greyhound and bulldog--(the two most obviously modified of the breeds of dog)--we find their puppies at the age of six days with legs and noses (the latter measured from the eyes to the tip) of the same length; though in the proportional thicknesses and general appearance of these parts there is a great difference. So it is with cattle, though the young calves of different breeds are easily recognisable, yet they do not differ so much in their proportions as the full-grown animals. We see this clearly in the fact that it shows the highest skill to select the best forms early in life, either in horses, cattle or poultry; no one would attempt it only a few hours after birth; and it requires great discrimination to judge with accuracy even during their full youth, and the best judges are sometimes deceived. This shows that the ultimate proportions of the body are not acquired till near mature age. If I had collected sufficient facts to firmly establish the proposition that in artificially selected breeds the embryonic and young animals are not changed in a corresponding degree with their mature parents, I might have omitted all the foregoing reasoning and the attempts to explain how this happens; for we might safely have transferred the proposition to the breeds or species naturally selected; and the ultimate effect would necessarily have been that in a number of races or species descended from a common stock and forming several genera and families the embryos would have resembled each other more closely than full-grown animals. Whatever may have been the form or habits of the parent-stock of the Vertebrata, in whatever course the arteries ran and branched, the selection of variations, supervening after the first formation of the arteries in the embryo, would not tend from variations supervening at corresponding periods to alter their course at that period: hence, the similar course of the arteries in the mammal, bird, reptile and fish, must be looked at as a most ancient record of the embryonic structure of the common parent-stock of these four great classes. {477} _Origin_, Ed. i. p. 444, vi. p. 611. A long course of selection might cause a form to become more simple, as well as more complicated; thus the adaptation of a crustaceous{478} animal to live attached during its whole life to the body of a fish, might permit with advantage great simplification of structure, and on this view the singular fact of an embryo being more complex than its parent is at once explained. {478} _Origin_, Ed. i. p. 441, vi. p. 607. _On the graduated complexity in each great class._ I may take this opportunity of remarking that naturalists have observed that in most of the great classes a series exists from very complicated to very simple beings; thus in Fish, what a range there is between the sand-eel and shark,--in the Articulata, between the common crab and the Daphnia{479},--between the Aphis and butterfly, and between a mite and a spider{480}. Now the observation just made, namely, that selection might tend to simplify, as well as to complicate, explains this; for we can see that during the endless geologico-geographical changes, and consequent isolation of species, a station occupied in other districts by less complicated animals might be left unfilled, and be occupied by a degraded form of a higher or more complicated class; and it would by no means follow that, when the two regions became united, the degraded organism would give way to the aboriginally lower organism. According to our theory, there is obviously no power tending constantly to exalt species, except the mutual struggle between the different individuals and classes; but from the strong and general hereditary tendency we might expect to find some tendency to progressive complication in the successive production of new organic forms. {479} Compare _Origin_, Ed. i. p. 419, vi. p. 575. {480} <Note in original.> Scarcely possible to distinguish between non-development and retrograde development. _Modification by selection of the forms of immature animals._ I have above remarked that the feline{481} form is quite of secondary importance to the embryo and to the kitten. Of course, during any great and prolonged change of structure in the mature animal, it might, and often would be, indispensable that the form of the embryo should be changed; and this could be effected, owing to the hereditary tendency at corresponding ages, by selection, equally well as in mature age: thus if the embryo tended to become, or to remain, either over its whole body or in certain parts, too bulky, the female parent would die or suffer more during parturition; and as in the case of the calves with large hinder quarters{482}, the peculiarity must be either eliminated or the species become extinct. Where an embryonic form has to seek its own food, its structure and adaptation is just as important to the species as that of the full-grown animal; and as we have seen that a peculiarity appearing in a caterpillar (or in a child, as shown by the hereditariness of peculiarities in the milk-teeth) reappears in its offspring, so we can at once see that our common principle of the selection of slight accidental variations would modify and adapt a caterpillar to a new or changing condition, precisely as in the full-grown butterfly. Hence probably it is that caterpillars of different species of the Lepidoptera differ more than those embryos, at a corresponding early period of life, do which remain inactive in the womb of their parents. The parent during successive ages continuing to be adapted by selection for some one object, and the larva for quite another one, we need not wonder at the difference becoming wonderfully great between them; even as great as that between the fixed rock-barnacle and its free, crab-like offspring, which is furnished with eyes and well-articulated, locomotive limbs{483}. {481} See p. 42, where the same illustration is used. {482} _Var. under Dom._, Ed. ii. vol. I. p. 452. {483} _Origin_, Ed. i. p. 441, vi. p. 607. _Importance of embryology in classification._ We are now prepared to perceive why the study of embryonic forms is of such acknowledged importance in classification{484}. For we have seen that a variation, supervening at any time, may aid in the modification and adaptation of the full-grown being; but for the modification of the embryo, only the variations which supervene at a very early period can be seized on and perpetuated by selection: hence there will be less power and less tendency (for the structure of the embryo is mostly unimportant) to modify the young: and hence we might expect to find at this period similarities preserved between different groups of species which had been obscured and quite lost in the full-grown animals. I conceive on the view of separate creations it would be impossible to offer any explanation of the affinities of organic beings thus being plainest and of the greatest importance at that period of life when their structure is not adapted to the final part they have to play in the economy of nature. {484} _Origin_, Ed. i. p. 449, vi. p. 617. _Order in time in which the great classes have first appeared._ It follows strictly from the above reasoning only that the embryos of (for instance) existing vertebrata resemble more closely the embryo of the parent-stock of this great class than do full-grown existing vertebrata resemble their full-grown parent-stock. But it may be argued with much probability that in the earliest and simplest condition of things the parent and embryo must have resembled each other, and that the passage of any animal through embryonic states in its growth is entirely due to subsequent variations affecting _only_ the more mature periods of life. If so, the embryos of the existing vertebrata will shadow forth the full-grown structure of some of those forms of this great class which existed at the earlier periods of the earth's history{485}: and accordingly, animals with a fish-like structure ought to have preceded birds and mammals; and of fish, that higher organized division with the vertebræ extending into one division of the tail ought to have preceded the equal-tailed, because the embryos of the latter have an unequal tail; and of Crustacea, entomostraca ought to have preceded the ordinary crabs and barnacles--polypes ought to have preceded jelly-fish, and infusorial animalcules to have existed before both. This order of precedence in time in some of these cases is believed to hold good; but I think our evidence is so exceedingly incomplete regarding the number and kinds of organisms which have existed during all, especially the earlier, periods of the earth's history, that I should put no stress on this accordance, even if it held truer than it probably does in our present state of knowledge. {485} _Origin_, Ed. i. p. 449, vi. p. 618. CHAPTER IX ABORTIVE OR RUDIMENTARY ORGANS _The abortive organs of naturalists._ Parts of structure are said to be "abortive," or when in a still lower state of development "rudimentary{486}," when the same reasoning power, which convinces us that in some cases similar parts are beautifully adapted to certain ends, declares that in others they are absolutely useless. Thus the rhinoceros, the whale{487}, etc., have, when young, small but properly formed teeth, which never protrude from the jaws; certain bones, and even the entire extremities are represented by mere little cylinders or points of bone, often soldered to other bones: many beetles have exceedingly minute but regularly formed wings lying under their wing-cases{488}, which latter are united never to be opened: many plants have, instead of stamens, mere filaments or little knobs; petals are reduced to scales, and whole flowers to buds, which (as in the feather hyacinth) never expand. Similar instances are almost innumerable, and are justly considered wonderful: probably not one organic being exists in which some part does not bear the stamp of inutility; for what can be clearer{489}, as far as our reasoning powers can reach, than that teeth are for eating, extremities for locomotion, wings for flight, stamens and the entire flower for reproduction; yet for these clear ends the parts in question are manifestly unfit. Abortive organs are often said to be mere representatives (a metaphorical expression) of similar parts in other organic beings; but in some cases they are more than representatives, for they seem to be the actual organ not fully grown or developed; thus the existence of mammæ in the male vertebrata is one of the oftenest adduced cases of abortion; but we know that these organs in man (and in the bull) have performed their proper function and secreted milk: the cow has normally four mammæ and two abortive ones, but these latter in some instances are largely developed and even (??) give milk{490}. Again in flowers, the representatives of stamens and pistils can be traced to be really these parts not developed; Kölreuter has shown by crossing a diæcious plant (a Cucubalus) having a rudimentary pistil{491} with another species having this organ perfect, that in the hybrid offspring the rudimentary part is more developed, though still remaining abortive; now this shows how intimately related in nature the mere rudiment and the fully developed pistil must be. {486} In the _Origin_, Ed. i. p. 450, vi. p. 619, the author does not lay stress on any distinction in meaning between the terms _abortive_ and _rudimentary_ organs. {487} _Origin_, Ed. i. p. 450, vi. p. 619. {488} _Ibid._ {489} This argument occurs in _Origin_, Ed. i. p. 451, vi. p. 619. {490} _Origin_, Ed. i. p. 451, vi. p. 619, on male mammæ. In the _Origin_ he speaks certainly of the abortive mammæ of the cow giving milk,--a point which is here queried. {491} _Origin_, Ed. i. p. 451, vi. p. 620. Abortive organs, which must be considered as useless as far as their ordinary and normal purpose is concerned, are sometimes adapted to other ends{492}: thus the marsupial bones, which properly serve to support the young in the mother's pouch, are present in the male and serve as the fulcrum for muscles connected only with male functions: in the male of the marigold flower the pistil is abortive for its proper end of being impregnated, but serves to sweep the pollen out of the anthers{493} ready to be borne by insects to the perfect pistils in the other florets. It is likely in many cases, yet unknown to us, that abortive organs perform some useful function; but in other cases, for instance in that of teeth embedded in the solid jaw-bone, or of mere knobs, the rudiments of stamens and pistils, the boldest imagination will hardly venture to ascribe to them any function. Abortive parts, even when wholly useless to the individual species, are of great signification in the system of nature; for they are often found to be of very high importance in a natural classification{494}; thus the presence and position of entire abortive flowers, in the grasses, cannot be overlooked in attempting to arrange them according to their true affinities. This corroborates a statement in a previous chapter, viz. that the physiological importance of a part is no index of its importance in classification. Finally, abortive organs often are only developed, proportionally with other parts, in the embryonic or young state of each species{495}; this again, especially considering the classificatory importance of abortive organs, is evidently part of the law (stated in the last chapter) that the higher affinities of organisms are often best seen in the stages towards maturity, through which the embryo passes. On the ordinary view of individual creations, I think that scarcely any class of facts in natural history are more wonderful or less capable of receiving explanation. {492} The case of rudimentary organs adapted to new purposes is discussed in the _Origin_, Ed. i. p. 451, vi. p. 620. {493} This is here stated on the authority of Sprengel; see also _Origin_, Ed. i. p. 452, vi. p. 621. {494} _Origin_, Ed. i. p. 455, vi. p. 627. In the margin R. Brown's name is given apparently as the authority for the fact. {495} _Origin_, Ed. i. p. 455, vi. p. 626. _The abortive organs of physiologists._ Physiologists and medical men apply the term "abortive" in a somewhat different sense from naturalists; and their application is probably the primary one; namely, to parts, which from accident or disease before birth are not developed or do not grow{496}: thus, when a young animal is born with a little stump in the place of a finger or of the whole extremity, or with a little button instead of a head, or with a mere bead of bony matter instead of a tooth, or with a stump instead of a tail, these parts are said to be aborted. Naturalists on the other hand, as we have seen, apply this term to parts not stunted during the growth of the embryo, but which are as regularly produced in successive generations as any other most essential parts of the structure of the individual: naturalists, therefore, use this term in a metaphorical sense. These two classes of facts, however, blend into each other{497}; by parts accidentally aborted, during the embryonic life of one individual, becoming hereditary in the succeeding generations: thus a cat or dog, born with a stump instead of a tail, tends to transmit stumps to their offspring; and so it is with stumps representing the extremities; and so again with flowers, with defective and rudimentary parts, which are annually produced in new flower-buds and even in successive seedlings. The strong hereditary tendency to reproduce every either congenital or slowly acquired structure, whether useful or injurious to the individual, has been shown in the first part; so that we need feel no surprise at these truly abortive parts becoming hereditary. A curious instance of the force of hereditariness is sometimes seen in two little loose hanging horns, quite useless as far as the function of a horn is concerned, which are produced in hornless races of our domestic cattle{498}. Now I believe no real distinction can be drawn between a stump representing a tail or a horn or the extremities; or a short shrivelled stamen without any pollen; or a dimple in a petal representing a nectary, when such rudiments are regularly reproduced in a race or family, and the true abortive organs of naturalists. And if we had reason to believe (which I think we have not) that all abortive organs had been at some period _suddenly_ produced during the embryonic life of an individual, and afterwards become inherited, we should at once have a simple explanation of the origin of abortive and rudimentary organs{499}. In the same manner as during changes of pronunciation certain letters in a word may become useless{500} in pronouncing it, but yet may aid us in searching for its derivation, so we can see that rudimentary organs, no longer useful to the individual, may be of high importance in ascertaining its descent, that is, its true classification in the natural system. {496} _Origin_, Ed. i. p. 454, vi. p. 625. {497} In the _Origin_, Ed. i. p. 454, vi. p. 625, the author in referring to semi-monstrous variations adds "But I doubt whether any of these cases throw light on the origin of rudimentary organs in a state of nature." In 1844 he was clearly more inclined to an opposite opinion. {498} _Origin_, Ed. i. p. 454, vi. p. 625. {499} See _Origin_, Ed. i. p. 454, vi. p. 625. The author there discusses monstrosities in relation to rudimentary organs, and comes to the conclusion that disuse is of more importance, giving as a reason his doubt "whether species under nature ever undergo abrupt changes." It seems to me that in the _Origin_ he gives more weight to the "Lamarckian factor" than he did in 1844. Huxley took the opposite view, see the Introduction. {500} _Origin_, Ed. i. p. 455, vi. p. 627. _Abortion from gradual disuse._ There seems to be some probability that continued disuse of any part or organ, and the selection of individuals with such parts slightly less developed, would in the course of ages produce in organic beings under domesticity races with such parts abortive. We have every reason to believe that every part and organ in an individual becomes fully developed only with exercise of its functions; that it becomes developed in a somewhat lesser degree with less exercise; and if forcibly precluded from all action, such part will often become atrophied. Every peculiarity, let it be remembered, tends, especially where both parents have it, to be inherited. The less power of flight in the common duck compared with the wild, must be partly attributed to disuse{501} during successive generations, and as the wing is properly adapted to flight, we must consider our domestic duck in the first stage towards the state of the Apteryx, in which the wings are so curiously abortive. Some naturalists have attributed (and possibly with truth) the falling ears so characteristic of most domestic dogs, some rabbits, oxen, cats, goats, horses, &c., &c., as the effects of the lesser use of the muscles of these flexible parts during successive generations of inactive life; and muscles, which cannot perform their functions, must be considered verging towards abortion. In flowers, again, we see the gradual abortion during successive seedlings (though this is more properly a conversion) of stamens into imperfect petals, and finally into perfect petals. When the eye is blinded in early life the optic nerve sometimes becomes atrophied; may we not believe that where this organ, as is the case with the subterranean mole-like Tuco-tuco <_Ctenomys_>{502}, is frequently impaired and lost, that in the course of generations the whole organ might become abortive, as it normally is in some burrowing quadrupeds having nearly similar habits with the Tuco-tuco? {501} _Origin_, Ed. i. p. 11, vi. p. 13, where drooping-ears of domestic animals are also given. {502} _Origin_, Ed. i. p. 137, vi. p. 170. In as far then as it is admitted as probable that the effects of disuse (together with occasional true and sudden abortions during the embryonic period) would cause a part to be less developed, and finally to become abortive and useless; then during the infinitely numerous changes of habits in the many descendants from a common stock, we might fairly have expected that cases of organs becom<ing> abortive would have been numerous. The preservation of the stump of the tail, as usually happens when an animal is born tailless, we can only explain by the strength of the hereditary principle and by the period in embryo when affected{503}: but on the theory of disuse gradually obliterating a part, we can see, according to the principles explained in the last chapter (viz. of hereditariness at corresponding periods of life{504}, together with the use and disuse of the part in question not being brought into play in early or embryonic life), that organs or parts would tend not to be utterly obliterated, but to be reduced to that state in which they existed in early embryonic life. Owen often speaks of a part in a full-grown animal being in an "embryonic condition." Moreover we can thus see why abortive organs are most developed at an early period of life. Again, by gradual selection, we can see how an organ rendered abortive in its primary use might be converted to other purposes; a duck's wing might come to serve for a fin, as does that of the penguin; an abortive bone might come to serve, by the slow increment and change of place in the muscular fibres, as a fulcrum for a new series of muscles; the pistil{505} of the marigold might become abortive as a reproductive part, but be continued in its function of sweeping the pollen out of the anthers; for if in this latter respect the abortion had not been checked by selection, the species must have become extinct from the pollen remaining enclosed in the capsules of the anthers. {503} These words seem to have been inserted as an afterthought. {504} _Origin_, Ed. i. p. 444, vi. p. 611. {505} This and similar cases occur in the _Origin_, Ed. i. p. 452, vi. p. 621. Finally then I must repeat that these wonderful facts of organs formed with traces of exquisite care, but now either absolutely useless or adapted to ends wholly different from their ordinary end, being present and forming part of the structure of almost every inhabitant of this world, both in long-past and present times--being best developed and often only discoverable at a very early embryonic period, and being full of signification in arranging the long series of organic beings in a natural system--these wonderful facts not only receive a simple explanation on the theory of long-continued selection of many species from a few common parent-stocks, but necessarily follow from this theory. If this theory be rejected, these facts remain quite inexplicable; without indeed we rank as an explanation such loose metaphors as that of De Candolle's{506}, in which the kingdom of nature is compared to a well-covered table, and the abortive organs are considered as put in for the sake of symmetry! {506} The metaphor of the dishes is given in the Essay of 1842, p. 47, note 3.{Note 173} CHAPTER X RECAPITULATION AND CONCLUSION _Recapitulation._ I will now recapitulate the course of this work, more fully with respect to the former parts, and briefly <as to> the latter. In the first chapter we have seen that most, if not all, organic beings, when taken by man out of their natural condition, and bred during several generations, vary; that is variation is partly due to the direct effect of the new external influences, and partly to the indirect effect on the reproductive system rendering the organization of the offspring in some degree plastic. Of the variations thus produced, man when uncivilised naturally preserves the life, and therefore unintentionally breeds from those individuals most useful to him in his different states: when even semi-civilised, he intentionally separates and breeds from such individuals. Every part of the structure seems occasionally to vary in a very slight degree, and the extent to which all kinds of peculiarities in mind and body, when congenital and when slowly acquired either from external influences, from exercise, or from disuse <are inherited>, is truly wonderful. When several breeds are once formed, then crossing is the most fertile source of new breeds{507}. Variation must be ruled, of course, by the health of the new race, by the tendency to return to the ancestral forms, and by unknown laws determining the proportional increase and symmetry of the body. The amount of variation, which has been effected under domestication, is quite unknown in the majority of domestic beings. {507} Compare however Darwin's later view:--"The possibility of making distinct races by crossing has been greatly exaggerated," _Origin_, Ed. i. p. 20, vi. p. 23. The author's change of opinion was no doubt partly due to his experience in breeding pigeons. In the second chapter it was shown that wild organisms undoubtedly vary in some slight degree: and that the kind of variation, though much less in degree, is similar to that of domestic organisms. It is highly probable that every organic being, if subjected during several generations to new and varying conditions, would vary. It is certain that organisms, living in an _isolated_ country which is undergoing geological changes, must in the course of time be so subjected to new conditions; moreover an organism, when by chance transported into a new station, for instance into an island, will often be exposed to new conditions, and be surrounded by a new series of organic beings. If there were no power at work selecting every slight variation, which opened new sources of subsistence to a being thus situated, the effects of crossing, the chance of death and the constant tendency to reversion to the old parent-form, would prevent the production of new races. If there were any selective agency at work, it seems impossible to assign any limit{508} to the complexity and beauty of the adaptive structures, which _might_ thus be produced: for certainly the limit of possible variation of organic beings, either in a wild or domestic state, is not known. {508} In the _Origin_, Ed. i. p. 469, vi. p. 644, Darwin makes a strong statement to this effect. It was then shown, from the geometrically increasing tendency of each species to multiply (as evidenced from what we know of mankind and of other animals when favoured by circumstances), and from the means of subsistence of each species on an _average_ remaining constant, that during some part of the life of each, or during every few generations, there must be a severe struggle for existence; and that less than a grain{509} in the balance will determine which individuals shall live and which perish. In a country, therefore, undergoing changes, and cut off from the free immigration of species better adapted to the new station and conditions, it cannot be doubted that there is a most powerful means of selection, _tending_ to preserve even the slightest variation, which aided the subsistence or defence of those organic beings, during any part of their whole existence, whose organization had been rendered plastic. Moreover, in animals in which the sexes are distinct, there is a sexual struggle, by which the most vigorous, and consequently the best adapted, will oftener procreate their kind. {509} "A grain in the balance will determine which individual shall live and which shall die," _Origin_, Ed. i. p. 467, vi. p. 642. A similar statement occurs in the 1842 Essay, p. 8, note 3.{Note 59} A new race thus formed by natural selection would be undistinguishable from a species. For comparing, on the one hand, the several species of a genus, and on the other hand several domestic races from a common stock, we cannot discriminate them by the amount of external difference, but only, first, by domestic races not remaining so constant or being so "true" as species are; and secondly by races always producing fertile offspring when crossed. And it was then shown that a race naturally selected--from the variation being slower--from the selection steadily leading towards the same ends{510}, and from every new slight change in structure being adapted (as is implied by its selection) to the new conditions and being fully exercised, and lastly from the freedom from occasional crosses with other species, would almost necessarily be "truer" than a race selected by ignorant or capricious and short-lived man. With respect to the sterility of species when crossed, it was shown not to be a universal character, and when present to vary in degree: sterility also was shown probably to depend less on external than on constitutional differences. And it was shown that when individual animals and plants are placed under new conditions, they become, without losing their healths, as sterile, in the same manner and to the same degree, as hybrids; and it is therefore conceivable that the cross-bred offspring between two species, having different constitutions, might have its constitution affected in the same peculiar manner as when an individual animal or plant is placed under new conditions. Man in selecting domestic races has little wish and still less power to adapt the whole frame to new conditions; in nature, however, where each species survives by a struggle against other species and external nature, the result must be very different. {510} Thus according to the author what is now known as _orthogenesis_ is due to selection. Races descending from the same stock were then compared with species of the same genus, and they were found to present some striking analogies. The offspring also of races when crossed, that is mongrels, were compared with the cross-bred offspring of species, that is hybrids, and they were found to resemble each other in all their characters, with the one exception of sterility, and even this, when present, often becomes after some generations variable in degree. The chapter was summed up, and it was shown that no ascertained limit to the amount of variation is known; or could be predicted with due time and changes of condition granted. It was then admitted that although the production of new races, undistinguishable from true species, is probable, we must look to the relations in the past and present geographical distribution of the infinitely numerous beings, by which we are surrounded--to their affinities and to their structure--for any direct evidence. In the third chapter the inheritable variations in the mental phenomena of domestic and of wild organic beings were considered. It was shown that we are not concerned in this work with the first origin of the leading mental qualities; but that tastes, passions, dispositions, consensual movements, and habits all became, either congenitally or during mature life, modified and were inherited. Several of these modified habits were found to correspond in every essential character with true instincts, and they were found to follow the same laws. Instincts and dispositions &c. are fully as important to the preservation and increase of a species as its corporeal structure; and therefore the natural means of selection would act on and modify them equally with corporeal structures. This being granted, as well as the proposition that mental phenomena are variable, and that the modifications are inheritable, the possibility of the several most complicated instincts being slowly acquired was considered, and it was shown from the very imperfect series in the instincts of the animals now existing, that we are not justified in _prima facie_ rejecting a theory of the common descent of allied organisms from the difficulty of imagining the transitional stages in the various now most complicated and wonderful instincts. We were thus led on to consider the same question with respect both to highly complicated organs, and to the aggregate of several such organs, that is individual organic beings; and it was shown, by the same method of taking the existing most imperfect series, that we ought not at once to reject the theory, because we cannot trace the transitional stages in such organs, or conjecture the transitional habits of such individual species. In the Second Part{511} the direct evidence of allied forms having descended from the same stock was discussed. It was shown that this theory requires a long series of intermediate forms between the species and groups in the same classes--forms not directly intermediate between existing species, but intermediate with a common parent. It was admitted that if even all the preserved fossils and existing species were collected, such a series would be far from being formed; but it was shown that we have not _good_ evidence that the oldest known deposits are contemporaneous with the first appearance of living beings; or that the several subsequent formations are nearly consecutive; or that any one formation preserves a nearly perfect fauna of even the hard marine organisms, which lived in that quarter of the world. Consequently, we have no reason to suppose that more than a small fraction of the organisms which have lived at any one period have ever been preserved; and hence that we ought not to expect to discover the fossilised sub-varieties between any two species. On the other hand, the evidence, though extremely imperfect, drawn from fossil remains, as far as it does go, is in favour of such a series of organisms having existed as that required. This want of evidence of the past existence of almost infinitely numerous intermediate forms, is, I conceive, much the weightiest difficulty{512} on the theory of common descent; but I must think that this is due to ignorance necessarily resulting from the imperfection of all geological records. {511} Part II begins with Ch. IV. See the Introduction, where the absence of division into two parts (in the _Origin_) is discussed. {512} In the recapitulation in the last chapter of the _Origin_, Ed. i. p. 475, vi. p. 651, the author does not insist on this point as the weightiest difficulty, though he does so in Ed. i. p. 299. It is possible that he had come to think less of the difficulty in question: this was certainly the case when he wrote the 6th edition, see p. 438. In the fifth chapter it was shown that new species gradually{513} appear, and that the old ones gradually disappear, from the earth; and this strictly accords with our theory. The extinction of species seems to be preceded by their rarity; and if this be so, no one ought to feel more surprise at a species being exterminated than at its being rare. Every species which is not increasing in number must have its geometrical tendency to increase checked by some agency seldom accurately perceived by us. Each slight increase in the power of this unseen checking agency would cause a corresponding decrease in the average numbers of that species, and the species would become rarer: we feel not the least surprise at one species of a genus being rare and another abundant; why then should we be surprised at its extinction, when we have good reason to believe that this very rarity is its regular precursor and cause. {513} <The following words:> The fauna changes singly <were inserted by the author, apparently to replace a doubtful erasure>. In the sixth chapter the leading facts in the geographical distribution of organic beings were considered--namely, the dissimilarity in areas widely and effectually separated, of the organic beings being exposed to very similar conditions (as for instance, within the tropical forests of Africa and America, or on the volcanic islands adjoining them). Also the striking similarity and general relations of the inhabitants of the same great continents, conjoined with a lesser degree of dissimilarity in the inhabitants living on opposite sides of the barriers intersecting it--whether or not these opposite sides are exposed to similar conditions. Also the dissimilarity, though in a still lesser degree, in the inhabitants of different islands in the same archipelago, together with their similarity taken as a whole with the inhabitants of the nearest continent, whatever its character may be. Again, the peculiar relations of Alpine floras; the absence of mammifers on the smaller isolated islands; and the comparative fewness of the plants and other organisms on islands with diversified stations; the connection between the possibility of occasional transportal from one country to another, with an affinity, though not identity, of the organic beings inhabiting them. And lastly, the clear and striking relations between the living and the extinct in the same great divisions of the world; which relation, if we look very far backward, seems to die away. These facts, if we bear in mind the geological changes in progress, all simply follow from the proposition of allied organic beings having lineally descended from common parent-stocks. On the theory of independent creations they must remain, though evidently connected together, inexplicable and disconnected. In the seventh chapter, the relationship or grouping of extinct and recent species; the appearance and disappearance of groups; the ill-defined objects of the natural classification, not depending on the similarity of organs physiologically important, not being influenced by adaptive or analogical characters, though these often govern the whole economy of the individual, but depending on any character which varies least, and especially on the forms through which the embryo passes, and, as was afterwards shown, on the presence of rudimentary and useless organs. The alliance between the nearest species in _distinct_ groups being general and not especial; the close similarity in the rules and objects in classifying domestic races and true species. All these facts were shown to follow on the natural system being a genealogical system. In the eighth chapter, the unity of structure throughout large groups, in species adapted to the most different lives, and the wonderful metamorphosis (used metaphorically by naturalists) of one part or organ into another, were shown to follow simply on new species being produced by the selection and inheritance of successive _small_ changes of structure. The unity of type is wonderfully manifested by the similarity of structure, during the embryonic period, in the species of entire classes. To explain this it was shown that the different races of our domestic animals differ less, during their young state, than when full grown; and consequently, if species are produced like races, the same fact, on a greater scale, might have been expected to hold good with them. This remarkable law of nature was attempted to be explained through establishing, by sundry facts, that slight variations originally appear during all periods of life, and that when inherited they tend to appear at the corresponding period of life; according to these principles, in several species descended from the same parent-stock, their embryos would almost necessarily much more closely resemble each other than they would in their adult state. The importance of these embryonic resemblances, in making out a natural or genealogical classification, thus becomes at once obvious. The occasional greater simplicity of structure in the mature animal than in the embryo; the gradation in complexity of the species in the great classes; the adaptation of the larvæ of animals to independent powers of existence; the immense difference in certain animals in their larval and mature states, were all shown on the above principles to present no difficulty. In the <ninth> chapter, the frequent and almost general presence of organs and parts, called by naturalists abortive or rudimentary, which, though formed with exquisite care, are generally absolutely useless <was considered>. <These structures,> though sometimes applied to uses not normal,--which cannot be considered as mere representative parts, for they are sometimes capable of performing their proper function,--which are always best developed, and sometimes only developed, during a very early period of life,--and which are of admitted high importance in classification,--were shown to be simply explicable on our theory of common descent. _Why do we wish to reject the theory of common descent?_ Thus have many general facts, or laws, been included under one explanation; and the difficulties encountered are those which would naturally result from our acknowledged ignorance. And why should we not admit this theory of descent{514}? Can it be shown that organic beings in a natural state are _all absolutely invariable_? Can it be said that the _limit of variation_ or the number of varieties capable of being formed under domestication are known? Can any distinct line be drawn _between a race and a species_? To these three questions we may certainly answer in the negative. As long as species were thought to be divided and defined by an impassable barrier of _sterility_, whilst we were ignorant of geology, and imagined that the _world was of short duration_, and the number of its past inhabitants few, we were justified in assuming individual creations, or in saying with Whewell that the beginnings of all things are hidden from man. Why then do we feel so strong an inclination to reject this theory--especially when the actual case of any two species, or even of any two races, is adduced--and one is asked, have these two originally descended from the same parent womb? I believe it is because we are always slow in admitting any great change of which we do not see the intermediate steps. The mind cannot grasp the full meaning of the term of a million or hundred million years, and cannot consequently add up and perceive the full effects of small successive variations accumulated during almost infinitely many generations. The difficulty is the same with that which, with most geologists, it has taken long years to remove, as when Lyell propounded that great valleys{515} were hollowed out [and long lines of inland cliffs had been formed] by the slow action of the waves of the sea. A man may long view a grand precipice without actually believing, though he may not deny it, that thousands of feet in thickness of solid rock once extended over many square miles where the open sea now rolls; without fully believing that the same sea which he sees beating the rock at his feet has been the sole removing power. {514} This question forms the subject of what is practically a section of the final chapter of the _Origin_ (Ed. i. p. 480, vi. p. 657). {515} _Origin_, Ed. i. p. 481, vi. p. 659. Shall we then allow that the three distinct species of rhinoceros{516} which separately inhabit Java and Sumatra and the neighbouring mainland of Malacca were created, male and female, out of the inorganic materials of these countries? Without any adequate cause, as far as our reason serves, shall we say that they were merely, from living near each other, created very like each other, so as to form a section of the genus dissimilar from the African section, some of the species of which section inhabit very similar and some very dissimilar stations? Shall we say that without any apparent cause they were created on the same generic type with the ancient woolly rhinoceros of Siberia and of the other species which formerly inhabited the same main division of the world: that they were created, less and less closely related, but still with interbranching affinities, with all the other living and extinct mammalia? That without any apparent adequate cause their short necks should contain the same number of vertebræ with the giraffe; that their thick legs should be built on the same plan with those of the antelope, of the mouse, of the hand of the monkey, of the wing of the bat, and of the fin of the porpoise. That in each of these species the second bone of their leg should show clear traces of two bones having been soldered and united into one; that the complicated bones of their head should become intelligible on the supposition of their having been formed of three expanded vertebræ; that in the jaws of each when dissected young there should exist small teeth which never come to the surface. That in possessing these useless abortive teeth, and in other characters, these three rhinoceroses in their embryonic state should much more closely resemble other mammalia than they do when mature. And lastly, that in a still earlier period of life, their arteries should run and branch as in a fish, to carry the blood to gills which do not exist. Now these three species of rhinoceros closely resemble each other; more closely than many generally acknowledged races of our domestic animals; these three species if domesticated would almost certainly vary, and races adapted to different ends might be selected out of such variations. In this state they would probably breed together, and their offspring would possibly be quite, and probably in some degree, fertile; and in either case, by continued crossing, one of these specific forms might be absorbed and lost in another. I repeat, shall we then say that a pair, or a gravid female, of each of these three species of rhinoceros, were separately created with deceptive appearances of true relationship, with the stamp of inutility on some parts, and of conversion in other parts, out of the inorganic elements of Java, Sumatra and Malacca? or have they descended, like our domestic races, from the same parent-stock? For my own part I could no more admit the former proposition than I could admit that the planets move in their courses, and that a stone falls to the ground, not through the intervention of the secondary and appointed law of gravity, but from the direct volition of the Creator. {516} The discussion on the three species of _Rhinoceros_ which also occurs in the Essay of 1842, p. 48, was omitted in Ch. XIV of the _Origin_, Ed. i. Before concluding it will be well to show, although this has incidentally appeared, how far the theory of common descent can legitimately be extended{517}. If we once admit that two true species of the same genus can have descended from the same parent, it will not be possible to deny that two species of two genera may also have descended from a common stock. For in some families the genera approach almost as closely as species of the same genus; and in some orders, for instance in the monocotyledonous plants, the families run closely into each other. We do not hesitate to assign a common origin to dogs or cabbages, because they are divided into groups analogous to the groups in nature. Many naturalists indeed admit that all groups are artificial; and that they depend entirely on the extinction of intermediate species. Some naturalists, however, affirm that though driven from considering sterility as the characteristic of species, that an entire incapacity to propagate together is the best evidence of the existence of natural genera. Even if we put on one side the undoubted fact that some species of the same genus will not breed together, we cannot possibly admit the above rule, seeing that the grouse and pheasant (considered by some good ornithologists as forming two families), the bull-finch and canary-bird have bred together. {517} This corresponds to a paragraph in the _Origin_, Ed. i. p. 483, vi. p. 662, where it is assumed that animals have descended "from at most only four or five progenitors, and plants from an equal or lesser number." In the _Origin_, however, the author goes on, Ed. i. p. 484, vi. p. 663: "Analogy would lead me one step further, namely, to the belief that all animals and plants have descended from some one prototype." No doubt the more remote two species are from each other, the weaker the arguments become in favour of their common descent. In species of two distinct families the analogy, from the variation of domestic organisms and from the manner of their intermarrying, fails; and the arguments from their geographical distribution quite or almost quite fails. But if we once admit the general principles of this work, as far as a clear unity of type can be made out in groups of species, adapted to play diversified parts in the economy of nature, whether shown in the structure of the embryonic or mature being, and especially if shown by a community of abortive parts, we are legitimately led to admit their community of descent. Naturalists dispute how widely this unity of type extends: most, however, admit that the vertebrata are built on one type; the articulata on another; the mollusca on a third; and the radiata on probably more than one. Plants also appear to fall under three or four great types. On this theory, therefore, all the organisms _yet discovered_ are descendants of probably less than ten parent-forms. _Conclusion._ My reasons have now been assigned for believing that specific forms are not immutable creations{518}. The terms used by naturalists of affinity, unity of type, adaptive characters, the metamorphosis and abortion of organs, cease to be metaphorical expressions and become intelligible facts. We no longer look at an organic being as a savage does at a ship{519} or other great work of art, as at a thing wholly beyond his comprehension, but as a production that has a history which we may search into. How interesting do all instincts become when we speculate on their origin as hereditary habits, or as slight congenital modifications of former instincts perpetuated by the individuals so characterised having been preserved. When we look at every complex instinct and mechanism as the summing up of a long history of contrivances, each most useful to its possessor, nearly in the same way as when we look at a great mechanical invention as the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen. How interesting does the geographical distribution of all organic beings, past and present, become as throwing light on the ancient geography of the world. Geology loses glory{520} from the imperfection of its archives, but it gains in the immensity of its subject. There is much grandeur in looking at every existing organic being either as the lineal successor of some form now buried under thousands of feet of solid rock, or as being the co-descendant of that buried form of some more ancient and utterly lost inhabitant of this world. It accords with what we know of the laws impressed by the Creator{521} on matter that the production and extinction of forms should, like the birth and death of individuals, be the result of secondary means. It is derogatory that the Creator of countless Universes should have made by individual acts of His will the myriads of creeping parasites and worms, which since the earliest dawn of life have swarmed over the land and in the depths of the ocean. We cease to be astonished{522} that a group of animals should have been formed to lay their eggs in the bowels and flesh of other sensitive beings; that some animals should live by and even delight in cruelty; that animals should be led away by false instincts; that annually there should be an incalculable waste of the pollen, eggs and immature beings; for we see in all this the inevitable consequences of one great law, of the multiplication of organic beings not created immutable. From death, famine, and the struggle for existence, we see that the most exalted end which we are capable of conceiving, namely, the creation of the higher animals{523}, has directly proceeded. Doubtless, our first impression is to disbelieve that any secondary law could produce infinitely numerous organic beings, each characterised by the most exquisite workmanship and widely extended adaptations: it at first accords better with our faculties to suppose that each required the fiat of a Creator. There{524} is a [simple] grandeur in this view of life with its several powers of growth, reproduction and of sensation, having been originally breathed into matter under a few forms, perhaps into only one{525}, and that whilst this planet has gone cycling onwards according to the fixed laws of gravity and whilst land and water have gone on replacing each other--that from so simple an origin, through the selection of infinitesimal varieties, endless forms most beautiful and most wonderful have been evolved. {518} This sentence corresponds, not to the final section of the _Origin_, Ed. i. p. 484, vi. p. 664, but rather to the opening words of the section already referred to (_Origin_, Ed. i. p. 480, vi. p. 657). {519} This simile occurs in the Essay of 1842, p. 50, and in the _Origin_, Ed. i. p. 485, vi. p. 665, _i.e._ in the final section of Ch. XIV (vi. Ch. XV). In the MS. there is some erasure in pencil of which I have taken no notice. {520} An almost identical sentence occurs in the _Origin_, Ed. i. p. 487, vi. p. 667. The fine prophecy (in the _Origin_, Ed. i. p. 486, vi. p. 666) on "the almost untrodden field of inquiry" is wanting in the present Essay. {521} See the last paragraph on p. 488 of the _Origin_, Ed. i., vi. p. 668. {522} A passage corresponding to this occurs in the sketch of 1842, p. 51, but not in the last chapter of the _Origin_. {523} This sentence occurs in an almost identical form in the _Origin_, Ed. i. p. 490, vi. p. 669. It will be noted that man is not named though clearly referred to. Elsewhere (_Origin_, Ed. i. p. 488) the author is bolder and writes "Light will be thrown on the origin of man and his history." In Ed. vi. p. 668, he writes "Much light &c." {524} For the history of this sentence (with which the _Origin of Species_ closes) see the Essay of 1842, p. 52, note 2{Note 184}: also the concluding pages of the Introduction. {525} These four words are added in pencil between the lines. INDEX For the names of Authors, Birds, Mammals (including names of classes) and Plants, see sub-indexes under _Authors_, _Birds_, _Mammals_ and _Plants_. Acquired characters, _see_ Characters Affinities and classification, 35 America, fossils, 177 Analogy, resemblance by, 36, 82, 199, 205, 211 Animals, marine, preservation of as fossils, 25, 139, 141; --marine distribution, 155, 196 Australia, fossils, 177 AUTHORS, NAMES OF:--Ackerman on hybrids, 11; Bakewell, 9, 91; Bateson, W., xxix, 69 _n._, 217; Bellinghausen, 124; Boitard and Corbié, 106 _n._; Brougham, Lord, 17, 117; Brown, R., 233; Buckland on fossils, 24, 137, 145 _n._; Buffon on woodpecker, 6; Bunbury (_Sir_ H.), rules for selection, 67; Butler, S., 116 _n._; d'Archiac, 146 _n._; Darwin, C., origin of his evolutionary views, xi-xv; --on Forbes' theory, 30; --his _Journal of Researches_ quoted, 67 _n._, 168 _n._; --his _Cross-and Self-Fertilisation_, 69 _n._, 103 _n._; --on crossing Chinese and common goose, 72 _n._; Darwin, Mrs, letter to, xxvi; Darwin, F., on Knight's Law, 70 _n._; Darwin, R. W., fact supplied by, 42 _n._, 223; Darwin and Wallace, joint paper by, xxiv, 87 _n._; De Candolle, 7, 47, 87, 204, 238; D'Orbigny, 124, 179 _n._; Ehrenberg, 146 _n._; Ewart on telegony, 108 _n._; Falconer, 167; Forbes, E., xxvii, 30, 146 _n._, 163 _n._, 165 _n._; Gadow, Dr, xxix; Gärtner, 98, 107; Goebel on Knight's Law, 70 _n._; Gould on distribution, 156; Gray, Asa, letter to, publication of in Linnean paper explained, xxiv; Henslow, G., on evolution without selection, 63 _n._; Henslow, J. S., xxvii; Herbert on hybrids, 12, 98; --sterility of crocus, 99 _n._; Hering, 116 _n._; Hogg, 115 _n._; Holland, Dr, 223; Hooker, J. D., xxvii, xxviii, 153 _n._; --on Insular Floras, 161, 164, 167; Huber, P., 118; Hudson on woodpecker, 131 _n._; Humboldt, 71, 166; Hunter, W., 114; Hutton, 27, 138; Huxley, 134 _n._; --on Darwin, xi, xii, xiv; --on Darwin's Essay of 1844, xxviii, 235; Judd, xi, xiii, xxix, 28, 141 _n._; Knight, A., 3 _n._, 65, 114; --on Domestication, 77; Knight-Darwin Law, 70 _n._; Kölreuter, 12, 97, 98, 104, 232; Lamarck, 42 _n._, 47, 82, 146, 200; --reasons for his belief in mutability, 197; Lindley, 101; Linnean Society, joint paper, _see_ Darwin and Wallace; Linnæus on sterility of Alpine plants, 101; --on generic characters, 201; Lonsdale, 145 _n._; Lyell, xxvii, 134 _n._, 138, 141 and _n._, 146 _n._, 159, 171, 173, 178; --his doctrine carried to an extreme, 26; --his geological metaphor, 27 _n._, 141; --his uniformitarianism, 53 _n._; --his views on imperfection of geological record, 27; Macculloch, 124 _n._; Macleay, W. S., 202; Magendie, 117; Malthus, xv, 7, 88, 90; Marr, Dr, xxix; Marshall, 65; --on sheep and cattle, 78 and _n._; --on horns of cattle, 207; Mivart, criticisms, 128 _n._; Mozart as a child, his skill on the piano compared to instinct, 19 _n._; Müller on consensual movements, 113; --on variation under uniform conditions, (2), 62; --on recapitulation theory, 219; Murchison, 145 _n._; Newton, Alfred, 132 _n._; Owen, R., xxvii, 219; Pallas, 68, 69; Pennant, 93 _n._; Pliny on selection, 67; Poeppig, 113 _n._; Prain, Col., xxix; Rengger, sterility, 100; Richardson, 132 _n._; Rutherford, H. W., xxix; St Hilaire on races of dogs, 106; --on sterility of tame and domestic animals, 12, 100; Smith, Jordan, 140; Sprengel, 233; Stapf, Dr, xxix; Strickland, xxvii; Suchetet, 97 _n._; Thiselton-Dyer, Sir W., xxix, 167; Wallace, xxiv, xxix, 30, 170 _n._; Waterhouse, 125, 126; Western, Lord, 9, 65, 91; Whewell, xxviii, 200; Woodward, H. B., 145 _n._; Wrangel, 119 _n._; Zacharias, Darwin's letter to, xv Barriers and distribution, 30, 154, 157, 178 Bees, 113, 117; combs of Hive-bee, 19, 121, 125, 126 Beetles, abortive wings of, 45 BIRDS, transporting seeds, 169; feeding young with food different to their own, 19, 126; migration, 123, 124; nests, 120, 121, 122, 126; of Galapagos, 19, 159; rapid increase, 88; song, 117 BIRDS, NAMES OF:--Apteryx, 45, 236; Duck, 46, 61, 65, 128, 224 _n._; Fowl, domestic, 59, 82 _n._, 97, 113, 114, 217; Goose, 72; --periodic habit, 124 _n._; Grouse, hybridised, 97, 102; Guinea-fowl, 79; Hawk, sterility, 100; --periodic habit, 124; Opetiorynchus, 83; Orpheus, 31; Ostrich, distribution of, 158; Owl, white barn, 82; Partridge, infertility of, 102; Peacock, 79, 97, 102; Penguin, 128 _n._, 237; Petrel, 128 _n._; Pheasant, 97, 102; Pigeon, 66, 82, 110 _n._, 113, 114, 116, 117, 129, 135; _see_ Wood-pigeon; Rhea, 158; Robins, increase in numbers, 88, 90; Rock-thrush of Guiana, 93; Swan, species of, 105; Tailor-bird, 18, 118; Turkey, Australian bush-turkey, 121 _n._, 122; Tyrannus, 31; Water-ouzel, 18 _n._, 120; Woodcock, loss of migratory instinct, 120; Woodpecker, 6, 16, 128 _n._, 148; --in treeless lands, 16, 131; Wood-pigeon, 122; Wren, gold-crested, 120; --willow, 105, 148 Breeds, domestic, parentage of, 71 Brothers, death of by same peculiar disease in old age, 42 _n._, 44 _n._, 223 Bud variation, 58; _see_ Sports Butterfly, cabbage, 127 Catastrophes, geological, 145, 147 Caterpillars, food, 126, 127 Characters, acquired, inheritance of, 1, 57, 60, 225; --congenital, 60; --fixed by breeding, 61; --mental, variation in, 17, 112, 119; --running through whole groups, 106; --useless for classification, 199 Cirripedes, 201, 229 Classification, natural system of, 35, 199, 206, 208; --by any constant character, 201; --relation of, to geography, 202; --a law that members of two distinct groups resemble each other not specifically but generally, 203, 212; --of domestic races, 204; --rarity and extinction in relation to, 210 Compensation, law of, 106 Conditions, direct, action of, 1, 57 _n._, 62, 65; --change of, analogous to crossing, 15, 77 _n._, 105; --accumulated effects of, 60, 78; --affecting reproduction, 1, 4, 78, 99; --and geographical distribution, 152 Continent originating as archipelago, bearing of on distribution, 189 Cordillera, as channel of migration, 34 _n._, 191 Correlation, 76 Creation, centres of, 168, 192 Crocodile, 146 _Cross-and Self-Fertilisation_, early statement of principles of, 15, 69 _n._, 103 _n._ Crossing, swamping effect of, 2, 69, 96; --of bisexual animals and hermaphrodite plants, 2; --analogous to change in conditions, 3, 15, 69; --in relation to breeds, 68; --in plants, adaptations for, 70 Death, feigned by insects, 123 Difficulties, on theory of evolution, 15, 121, 128, 134 Disease, hereditary, 43 _n._, 58, 222 Distribution, geographical, 29, 31, 151, 174, 177; --in space and time, subject to same laws, 155; --occasional means of (seeds, eggs, &c.), 169 Disuse, inherited effects of, 46, 57 Divergence, principle of, xxv, 37 _n._, 145 _n._, 208 _n._ Domestication, variation under, 57, 62; --accumulated effects of, 75, 78; --analysis of effects of, 76, 83 Ears, drooping, 236 Elevation, geological, favouring birth of new species, 32, 34 _n._, 35 _n._, 185-189; --alternating with subsidence, importance of for evolution, 33, 190; --bad for preservation of fossils, 194 Embryo, branchial arches of, 42, 220; --absence of special adaptation in, 42, 44 _n._, 220, 228; --less variable than parent, hence importance of embryology for classification, 44 _n._, 229; --alike in all vertebrates, 42, 218; --occasionally more complicated than adult, 219, 227 Embryology, 42, 218; its value in classification, 45, 200; law of inheritance at corresponding ages, 44 _n._, 224; young of very distinct breeds closely similar, 44 _n._, 225 Ephemera, selection falls on larva, 87 _n._ Epizoa, 219 Essay of 1842, question as to date of, xvi; description of MS., XX; compared with the _Origin_, xxii Essay of 1844, writing of, xvi; compared with that of 1842 and with the _Origin_, xxii Evolution, theory of, why do we tend to reject it, 248 Expression, inheritance of, 114 Extinction, 23, 147, 192; locally sudden, 145; continuous with rarity, 147, 198 Extinction and rarity, 198 Eye, 111 _n._, 128, 129, 130 Faculty, in relation to instinct, 123 Faunas, alpine, 30, 170, 188; of Galapagos, 31 _n._, 82, 159; insular-alpine very peculiar, 188; insular, 159, 160 Fauna and flora, of islands related to nearest land, 187 Fear of man, inherited, 17, 113 Fertility, interracial, 103, 104 Fish, colours of, 130, 131; eggs of carried by water-beetle, 169; flying, 128 _n._; --transported by whirlwind, 169 Floras, alpine, 162; of oceanic islands, 162; alpine, related to surrounding lowlands, 163; alpine, identity of on distant mountains, 163; alpine resembling arctic, 164; arctic relation to alpine, 164 Flower, morphology of, 39, 216; degenerate under domestication if neglected, 58; changed by selection, 66 Fly, causing extinction, 149 Flying, evolution of, 16, 131 Food, causing variations, 1, 58, 77, 78 Formation (geological) evidence from Tertiary system, 144; (geological), groups of species appear suddenly in Secondary, 26, 144; Palæozoic, if contemporary with beginning of life, author's theory false, 138 Formations, most ancient escape denudation in conditions unfavourable to life, 25, 139 Forms, transitional, 24, 35 _n._, 136, 142, 194; on rising land, 196; indirectly intermediate, 24, 135 Fossils, Silurian, not those which first existed in the world, 26, 138; falling into or between existing groups and indirectly intermediate, 24, 137; conditions favourable to preservation, not favourable to existence of much life, 25, 139, 141 Fruit, attractive to animals, 130 Galapagos Islands and Darwin's views, xiv; physical character of in relation to fauna, 31 _n._, 159 Galapagos Islands, fauna, 31 _n._, 82 Gasteropods, embryology, 218 Genera, crosses between, 11, 97; wide ranging, has wide ranging species, 155; origin of, 209 Geography, in relation to geology, 31 _n._, 174, 177 Geographical distribution, _see_ Distribution Geology, as producing changed conditions, 4; evidence from, 22, 133; "destroys geography," 31 _n._ Glacial period, effect of on distribution of alpine and arctic plants, 165 Habit in relation to instinct, 17, 113, 115, 116 Habits in animals taught by parent, 18 Heredity, _see_ Inheritance Homology of limbs, 38, 214 Homology, serial, 39, 215 Hybrid, fowls and grouse, 11; fowl and peacock, 97; pheasant and grouse, 97; Azalea and Rhododendron, 97 Hybrids, gradation in sterility of, 11, 72, 97; sterility of not reciprocal, 97; variability of, 78; compared and contrasted with mongrel, 107 Individual, meaning of term, 58 Inheritance of acquired characters, _see_ Character Inheritance, delayed or latent, 43, 44 _n._, 223; of character at a time of life corresponding to that at which it first appeared, 43, 44 _n._, 223; germinal, 44, 222, 223 Insect, adapted to fertilise flowers, 87; feigning death, 123; metamorphosis, 129; variation in larvæ, 223 Instinct, variation in, 17, 112; and faculty, 18, 123; guided by reason, 18, 19, 118; migratory, 19; migratory, loss of by woodcocks, 120; migratory, origin of, 125; due to germinal variation rather than habit, 116; requiring education for perfection, 117; characterised by ignorance of end: _e.g._ butterflies laying eggs, 17, 118; butterflies laying eggs on proper plant, 118, 127; instinct, natural selection applicable to, 19, 120 Instinct, for finding the way, 124; periodic, _i.e._ for lapse of time, 124; comb-making of bee, 125; birds feeding young, 19, 126; nest-building, gradation in, 18, 120, 121, 122; instincts, complex, difficulty in believing in their evolution, 20, 121 Intermediate forms, _see_ Forms Island, _see_ Elevation, Fauna, Flora Island, upheaved and gradually colonised, 184 Islands, nurseries of new species, 33, 35 _n._, 185, 189 Isolation, 32, 34 _n._, 64, 95, 183, 184 Lepidosiren, 140 _n._, 212 Limbs, vertebrate, of one type, 38, 216 MAMMALS, arctic, transported by icebergs, 170; distribution, 151, 152, 193; distribution of, ruled by barriers, 154; introduced by man on islands, 172; not found on oceanic islands, 172; relations in time and space, similarity of, 176; of Tertiary period, relation of to existing forms in same region, 174 MAMMALS, NAMES OF:-- Antelope, 148; Armadillo, 174; Ass, 79, 107, 172; Bat, 38, 123, 128 _n._, 131, 132, 214; Bear, sterile in captivity, 100; --whale-like habit, 128 _n._; Bizcacha, 168, 203, 212; Bull, mammæ of, 232; Carnivora, law of compensation in, 106; Cats, run wild at Ascension, 172; --tailless, 60; Cattle, horns of, 75, 207; --increase in S. America, 90; --Indian, 205; --Niata, 61, 73; --suffering in parturition from too large calves, 75; Cheetah, sterility of, 100 and _n._; Chironectes, 199; Cow, abortive mammæ, 232; Ctenomys, _see_ Tuco-tuco; Dog, 106, 114; --in Cuba, 113 and _n._; --mongrel breed in oceanic islands, 70; --difference in size a bar to crossing, 97; --domestic, parentage of, 71, 72, 73; --drooping ears, 236; --effects of selection, 66; --inter-fertile, 14; --long-legged breed produced to catch hares, 9, 10, 91, 92; --of savages, 67; --races of resembling genera, 106, 204; --Australian, change of colour in, 61; --bloodhound, Cuban, 204; --bull-dog, 113; --foxhound, 114, 116; --greyhound and bull-dog, young of resembling each other, 43, 44 _n._, 225; --pointer, 114, 115, 116, 117, 118; --retriever, 118 _n._; --setter, 114; --shepherd-dog and harrier crossed, instinct of, 118, 119; --tailless, 60; --turnspit, 66; Echidna, 82 _n._; Edentata, fossil and living in S. America, 174; Elephant, sterility of, 12, 100; Elk, 125; Ferret, fertility of, 12, 102; Fox, 82, 173, 181; Galeopithecus, 131 _n._; Giraffe, fossil, 177; --tail, 128 _n._; Goat, run wild at Tahiti, 172; Guanaco, 175; Guinea-pig, 69; Hare, S. American, 158 _n._; Hedgehog, 82 _n._; Horse, 67, 113, 115, 148, 149; --checks to increase, 148, 149; --increase in S. America, 90; --malconformations and lameness inherited, 58; --parentage, 71, 72; --stripes on, 107; --young of cart-horse and racehorse resembling each other, 43; Hyena, fossil, 177; Jaguar, catching fish, 132; Lemur, flying, 131 _n._; Macrauchenia, 137; Marsupials, fossil in Europe, 175 _n._, 177; --pouch bones, 232, 237; Mastodon, 177; Mouse, 153, 155; --enormous rate of increase, 89, 90; Mule, occasionally breeding, 97, 102; Musk-deer, fossil, 177; _Mustela vison_, 128 _n._, 132 _n._; Mydas, 170; Mydaus, 170; Nutria, _see_ Otter; Otter, 131, 132, 170; --marsupial, 199, 205, 211; Pachydermata, 137; Phascolomys, 203, 212; Pig, 115, 217; --in oceanic islands, 70; --run wild at St Helena, 172; Pole-cat, aquatic, 128 _n._, 132 _n._; Porpoise, paddle of, 38, 214; Rabbit, 74, 113, 236; Rat, Norway, 153; Reindeer, 125; Rhinoceros, 148; --abortive teeth of, 45, 231; --three oriental species of, 48, 249; Ruminantia, 137 and _n._; Seal, 93 _n._, 131; Sheep, 68, 78, 117, 205; --Ancon variety, 59, 66, 73; --inherited habit of returning home to lamb, 115; --transandantes of Spain, their migratory instinct, 114, 117, 124 _n._; Squirrel, flying, 131; Tapir, 135, 136; Tuco-tuco, blindness of, 46, 236; Whale, rudimentary teeth, 45, 229; Wolf, 71, 72, 82; Yak, 72 Metamorphosis, literal not metaphorical, 41, 217 Metamorphosis, _e.g._ leaves into petals, 215 Migrants to new land, struggle among, 33, 185 Migration, taking the place of variation, 188 Monstrosities, as starting-points of breeds, 49, 59; their relation to rudimentary organs, 46, 234 Morphology, 38, 215; terminology of, no longer metaphorically used, 41, 217 Mutation, _see_ Sports Natural selection, _see_ Selection Nest, bird's, _see_ Instinct Ocean, depth of, and fossils, 25, 195 Organisms, gradual introduction of new, 23, 144; extinct related to, existing in the same manner as representative existing ones to each other, 33, 192; introduced, beating indigenes, 153; dependent on other organisms rather than on physical surroundings, 185; graduated complexity in the great classes, 227; immature, how subject to natural selection, 42, 220, 228; all descended from a few parent-forms, 52, 252 Organs, perfect, objection to their evolution, 15, 128; distinct in adult life, indistinguishable in embryo, 42, 218; rudimentary, 45, 231, 232, 233; rudimentary, compared to monstrosities, 46, 234; rudimentary, caused by disuse, 46, 235; rudimentary, adapted to new ends, 47, 237 Orthogenesis, 241 _n._ Oscillation of level in relation to continents, 33, 34 _n._, 189 Pallas, on parentage of domestic animals, 71 Pampas, imaginary case of farmer on, 32, 184 Perfection, no inherent tendency towards, 227 Plants, _see also_ Flora; fertilisation, 70; migration of, to arctic and antarctic regions, 167; alpine and arctic, migration of, 31, 166; alpine, characters common to, 162; alpine, sterility of, 13, 101 PLANTS, NAMES OF:--Ægilops, 58 _n._; Artichoke (Jerusalem), 79; Ash, weeping, seeds of, 61; Asparagus, 79; Azalea, 13, 59, 97; Cabbage, 109, 135, 204; Calceolaria, 11, 99; Cardoon, 153; Carrot, variation of, 58 _n._; Chrysanthemum, 59; Crinum, 11, 99; Crocus, 96, 99 _n._; Cucubalus, crossing, 232; Dahlia, 21, 59, 63, 69, 74, 110; Foxglove, 82; Gentian, colour of flower, 107 _n._; Geranium, 102; Gladiolus, crossed, ancestry of, 11; Grass, abortive flowers, 233; Heath, sterility, 96; Hyacinth, colours of, 106; --feather-hyacinth, 229; Juniperus, hybridised, 97; Laburnum, peculiar hybrid, 108; Lilac, sterility of, 13, 100; Marigold, style of, 47, 233, 237; Mistletoe, 6, 86, 87, 90 _n._; Nectarines on peach trees, 59; Oxalis, colour of flowers of, 107 _n._; Phaseolus, cultivated form suffers from frost, 109; Pine-apple, 207; Poppy, Mexican, 154; Potato, 69, 74, 110; Rhododendron, 97, 99; Rose, moss, 59; --Scotch, 69; Seakale, 79; Sweet-william, 59; Syringa, persica and chinensis, _see_ Lilac; Teazle, 129; Thuja, hybridised, 97; Tulips, "breaking" of, 58; Turnip, Swedish and common, 205; Vine, peculiar hybrid, 108; Yew, weeping, seeds of, 61 Plasticity, produced by domestication, 1, 63 Plesiosaurus, loss of unity of type in, 41, 217 Pteropods, embryology, 218 Quadrupeds, extinction of large, 147 Quinary System, 202 Race, the word used as equivalent to variety, 94 Races, domestic, classification of, 204 Rarity, 28, 148; and extinction, 28, 149, 210 Recapitulation theory, 42, 219, 230, 239 Record, geological, imperfection of, 26, 140 Regions, geographical, of the world, 29, 152, 174; formerly less distinct as judged by fossils, 177 Resemblance, analogical, 36, 199 Reversion, 3, 64, 69, 74 "Roguing," 65 Rudimentary organs, _see_ Organs Savages, domestic animals of, 67, 68, 96 Selection, human, 3, 63; references to the practice of, in past times, 67; great effect produced by, 3, 91; necessary for the formation of breeds, 64; methodical, effects of, 3, 65; unconscious, 3, 67 Selection, natural, xvi, 7, 87; natural compared to human, 85, 94, 224; of instincts, 19, 120; difficulty of believing, 15, 121, 128 Selection, sexual, two types of, 10, 92 Silk-worms, variation in larval state, 44 _n._, 223 Skull, morphology of, 39, 215 Species, representative, seen in going from N. to S. in a continent, 31 _n._, 156; representative in archipelagoes, 187; wide-ranging, 34 _n._, 146; and varieties, difficulty of distinguishing, 4, 81, 197; sterility of crosses between, supposed to be criterion, 11, 134; gradual appearance and disappearance of, 23, 144; survival of a few among many extinct, 146 Species, not created more than once, 168, 171, 191; evolution of, compared to birth of individuals, 150, 198, 253; small number in New Zealand as compared to the Cape, 171, 191; persistence of, unchanged, 192, 199 Sports, 1, 58, 59, 64, 74, 95, 129, 186, 206, 224 Sterility, due to captivity, 12, 77 _n._, 100; of various plants, 13, 101; of species when crossed, 11, 23, 96, 99, 103; produced by conditions, compared to sterility due to crossing, 101, 102 Struggle for life, 7, 91, 92, 148, 241 Subsidence, importance of, in relation to fossils, 25, 35 _n._, 195; of continent leading to isolation of organisms, 190; not favourable to birth of new species, 196 Swimming bladder, 16, 129 System, natural, is genealogical, 36, 208 Telegony, 108 Tibia and fibula, 48, 137 Time, enormous lapse of, in geological epochs, 25, 140 Tortoise, 146 Transitional forms, _see_ Forms Trigonia, 147 _n._, 199 Tree-frogs in treeless regions, 131 Type, unity of, 38, 214; uniformity of, lost in Plesiosaurus, 217; persistence of, in continents, 158, 178 Uniformitarian views of Lyell, bearing on evolution, 249 Use, inherited effects of, _see_ Characters, acquired Variability, as specific character, 83; produced by change and also by crossing, 105 Variation, by Sports, _see_ Sports; under domestication, 1, 57, 63, 78; due to causes acting on reproductive system, _see_ Variation, germinal; --germinal, 2, 43, 62, 222; individual, 57 _n._; causes of, 1, 4, 57, 61; due to crossing, 68, 69; limits of, 74, 75, 82, 109; small in state of nature, 4, 59 _n._, 81, 83; results of _without_ selection, 84; --minute, value of, 91; analogous in species of same genus, 107; of mental attributes, 17, 112; in mature life, 59, 224, 225 Varieties, minute, in birds, 82; resemblance of to species, 81 _n._, 82, 105 Vertebrate skull, morphology of, 215 Wildness, hereditary, 113, 119 CAMBRIDGE: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS +--------------------------------------------------------------+ | Transcriber's Notes & Errata | | | | Inline transcriber's notes are enclosed in curly brackets. | | | | Footnote anchors and labels are enclosed in curly brackets. | | | | The footnotes have been renumbered consecutively. | | | | Because of this, the changed footnote numbers are appended | | in curly brackets to the internal cross-references. | | | | Superscript letters are denoted by a preceding caret e.g., | | d^o | | | | 'oe' ligatures have been rendered as separate letters. | | | | The following typographical errors have been corrected. | | | | |simplication |simplification | | | |care |case | | | |apparant |apparent | | | | | The following words were found in both hyphenated and | | unhyphenated forms. The figures in parentheses are the | | number of instances of each. | | | | |after-thought (1) |afterthought (2) | | | |blood-hound (2) |bloodhound (1) | | | |bull-dog (7) |bulldog (2) | | | |co-descendants (1) |codescendants (1) | | | |feather-hyacinth (2) |feather hyacinth (1) | | | |grey-hound (2) |greyhound (10) | | | |high-lands (3) |highlands (2) | | | |long-legged (2) |long legged (1) | | | |race-horse (2) |racehorse (4) | | | |shepherd-dog (3) |shepherd dog (1) | | | |sub-divisions (3) |subdivisions (4) | | | |table-land (2) |tableland (1) | | | | +--------------------------------------------------------------+ 
15707	----	ZOONOMIA; OR, THE LAWS OF ORGANIC LIFE. VOL. I. _By ERASMUS DARWIN, M.D. F.R.S._ AUTHOR OF THE BOTANIC GARDEN. * * * * * Principiò coelum, ac terras, camposque liquentes, Lucentemque globum lunæ, titaniaque astra, Spiritus intùs alit, totamque infusa per artus Mens agitat molem, et magno se corpore miscet.--VIRG. Æn. vi. Earth, on whose lap a thousand nations tread, And Ocean, brooding his prolific bed, Night's changeful orb, blue pole, and silvery zones, Where other worlds encircle other suns, One Mind inhabits, one diffusive Soul Wields the large limbs, and mingles with the whole. * * * * * _THE SECOND EDITION, CORRECTED._ * * * * * LONDON: PRINTED FOR. J. JOHNSON, IN ST. PAUL'S CHURCH-YARD. 1796. Entered at Stationers' Hall. * * * * * DEDICATION. To the candid and ingenious Members of the College of Physicians, of the Royal Philosophical Society, of the Two Universities, and to all those, who study the Operations of the Mind as a Science, or who practice Medicine as a Profession, the subsequent Work is, with great respect, inscribed by the Author, DERBY, May 1, 1794. CONTENTS. _Preface._ SECT. I. _Of Motion._ II. _Explanations and Definitions._ III. _The Motions of the Retina demonstrated by Experiments._ IV. _Laws of Animal Causation._ V. _Of the four Faculties or Motions of the Sensorium._ VI. _Of the four Classes of Fibrous Motions._ VII. _Of Irritative Motions._ VIII. _Of Sensitive Motions._ IX. _Of Voluntary Motions._ X. _Of Associate Motions._ XI. _Additional Observations on the Sensorial Powers._ XII. _Of Stimulus, Sensorial Exertion, and Fibrous Contraction._ XIII. _Of Vegetable Animation._ XIV. _Of the Production of Ideas._ XV. _Of the Classes of Ideas._ XVI. _Of Instinct._ XVII. _The Catenation of Animal Motions._ XVIII. _Of Sleep._ XIX. _Of Reverie._ XX. _Of Vertigo._ XXI. _Of Drunkenness._ XXII. _Of Propensity to Motion. Repetition. Imitation._ XXIII. _Of the Circulatory System._ XXIV. _Of the Secretion of Saliva, and of Tears. And of the Lacrymal Sack._ XXV. _Of the Stomach and Intestines._ XXVI. _Of the Capillary Glands, and of the Membranes._ XXVII. _Of Hemorrhages._ XXVIII. _The Paralysis of the Lacteals._ XXIX. _The Retrograde Motions of the Absorbent Vessels._ XXX. _The Paralysis of the Liver._ XXXI. _Of Temperaments._ XXXII. _Diseases of Irritation._ XXXIII. ---- _of Sensation._ XXXIV. ---- _of Volition._ XXXV. ---- _of Relation._ XXXVI. _The Periods of Diseases._ XXXVII. _Of Digestion, Secretion, Nutrition._ XXXVIII. _Of the Oxygenation of the Blood in the Lungs and Placenta._ XXXIX. _Of Generation._ XL. _Of Ocular Spectra._ * * * * * TO ERASMUS DARWIN, ON HIS WORK INTITLED ZOONOMIA, _By DEWHURST BILSBORROW._ * * * * * HAIL TO THE BARD! who sung, from Chaos hurl'd How suns and planets form'd the whirling world; How sphere on sphere Earth's hidden strata bend, And caves of rock her central fires defend; Where gems new-born their twinkling eyes unfold, 5 And young ores shoot in arborescent gold. How the fair Flower, by Zephyr woo'd, unfurls Its panting leaves, and waves its azure curls; Or spreads in gay undress its lucid form To meet the sun, and shuts it to the storm; 10 While in green veins impassion'd eddies move, And Beauty kindles into life and love. How the first embryon-fibre, sphere, or cube, Lives in new forms,--a line,--a ring,--a tube; Closed in the womb with limbs unfinish'd laves, 15 Sips with rude mouth the salutary waves; Seeks round its cell the sanguine streams, that pass, And drinks with crimson gills the vital gas; Weaves with soft threads the blue meandering vein, The heart's red concave, and the silver brain; 20 Leads the long nerve, expands the impatient sense, And clothes in silken skin the nascent Ens. Erewhile, emerging from its liquid bed, It lifts in gelid air its nodding head; The lights first dawn with trembling eyelid hails, 25 With lungs untaught arrests the balmy gales; Tries its new tongue in tones unknown, and hears The strange vibrations with unpractised ears; Seeks with spread hands the bosom's velvet orbs. With closing lips the milky fount absorbs; 30 And, as compress'd the dulcet streams distil, Drinks warmth and fragrance from the living rill;-- Eyes with mute rapture every waving line, Prints with adoring kiss the Paphian shrine, And learns erelong, the perfect form confess'd, 35 Ideal Beauty from its mother's breast. Now in strong lines, with bolder tints design'd, You sketch ideas, and portray the mind; Teach how fine atoms of impinging light To ceaseless change the visual sense excite; 40 While the bright lens collects the rays, that swerve, And bends their focus on the moving nerve. How thoughts to thoughts are link'd with viewless chains, Tribes leading tribes, and trains pursuing trains; With shadowy trident how Volition guides, 45 Surge after surge, his intellectual tides; Or, Queen of Sleep, Imagination roves With frantic Sorrows, or delirious Loves. Go on, O FRIEND! explore with eagle-eye; Where wrapp'd in night retiring Causes lie: 50 Trace their slight bands, their secret haunts betray, And give new wonders to the beam of day; Till, link by link with step aspiring trod, You climb from NATURE to the throne of GOD. --So saw the Patriarch with admiring eyes 55 From earth to heaven a golden ladder rise; Involv'd in clouds the mystic scale ascends, And brutes and angels crowd the distant ends. TRIN. COL. CAMBRIDGE, _Jan._ 1, 1794. * * * * * REFERENCES TO THE WORK. _Botanic Garden._ Part I. Line 1. Canto I. l. 105. ---- 3. ---- IV. l. 402. ---- 4. ---- I. l. 140. ---- 5. ---- III. l. 401. ---- 8. ---- IV. l. 452. ---- 9. ---- I. l. 14. _Zoonomia._ ---- 12. Sect. XIII. ---- 13. ---- XXXIX. 4. 1. ---- 18. ---- XVI. 2. and XXXVIII. ---- 26. ---- XVI. 4. ---- 30. ---- XVI. 4. ---- 36. ---- XVI. 6. ---- 38. ---- III. and VII. ---- 43. ---- X. ---- 44. ---- XVIII. 17. ---- 45. ---- XVII. 3. 7. ---- 47. ---- XVIII. 8. ---- 50. ---- XXXIX. 4. 8. ---- 51. ---- XXXIX the Motto. ---- 54. ---- XXXIX. 8. * * * * * PREFACE. * * * * * The purport of the following pages is an endeavour to reduce the facts belonging to ANIMAL LIFE into classes, orders, genera, and species; and, by comparing them with each other, to unravel the theory of diseases. It happened, perhaps unfortunately for the inquirers into the knowledge of diseases, that other sciences had received improvement previous to their own; whence, instead of comparing the properties belonging to animated nature with each other, they, idly ingenious, busied themselves in attempting to explain the laws of life by those of mechanism and chemistry; they considered the body as an hydraulic machine, and the fluids as passing through a series of chemical changes, forgetting that animation was its essential characteristic. The great CREATOR of all things has infinitely diversified the works of his hands, but has at the same time stamped a certain similitude on the features of nature, that demonstrates to us, that _the whole is one family of one parent_. On this similitude is founded all rational analogy; which, so long as it is concerned in comparing the essential properties of bodies, leads us to many and important discoveries; but when with licentious activity it links together objects, otherwise discordant, by some fanciful similitude; it may indeed collect ornaments for wit and poetry, but philosophy and truth recoil from its combinations. The want of a theory, deduced from such strict analogy, to conduct the practice of medicine is lamented by its professors; for, as a great number of unconnected facts are difficult to be acquired, and to be reasoned from, the art of medicine is in many instances less efficacious under the direction of its wisest practitioners; and by that busy crowd, who either boldly wade in darkness, or are led into endless error by the glare of false theory, it is daily practised to the destruction of thousands; add to this the unceasing injury which accrues to the public by the perpetual advertisements of pretended nostrums; the minds of the indolent become superstitiously fearful of diseases, which they do not labour under; and thus become the daily prey of some crafty empyric. A theory founded upon nature, that should bind together the scattered facts of medical knowledge, and converge into one point of view the laws of organic life, would thus on many accounts contribute to the interest of society. It would capacitate men of moderate abilities to practise the art of healing with real advantage to the public; it would enable every one of literary acquirements to distinguish the genuine disciples of medicine from those of boastful effrontery, or of wily address; and would teach mankind in some important situations the _knowledge of themselves_. There are some modern practitioners, who declaim against medical theory in general, not considering that to think is to theorize; and that no one can direct a method of cure to a person labouring under disease without thinking, that is, without theorizing; and happy therefore is the patient, whose physician possesses the best theory. The words idea, perception, sensation, recollection, suggestion, and association, are each of them used in this treatise in a more limited sense than in the writers of metaphysic. The author was in doubt, whether he should rather have substituted new words instead of them; but was at length of opinion, that new definitions of words already in use would be less burthensome to the memory of the reader. A great part of this work has lain by the writer above twenty years, as some of his friends can testify: he had hoped by frequent revision to have made it more worthy the acceptance of the public; this however his other perpetual occupations have in part prevented, and may continue to prevent, as long as he may be capable of revising it; he therefore begs of the candid reader to accept of it in its present state, and to excuse any inaccuracies of expression, or of conclusion, into which the intricacy of his subject, the general imperfection of language, or the frailty he has in common with other men, may have betrayed him; and from which he has not the vanity to believe this treatise to be exempt. * * * * * ZOONOMIA. * * * * * SECT. I. OF MOTION. The whole of nature may be supposed to consist of two essences or substances; one of which may be termed spirit, and the other matter. The former of these possesses the power to commence or produce motion, and the latter to receive and communicate it. So that motion, considered as a cause, immediately precedes every effect; and, considered as an effect, it immediately succeeds every cause. The MOTIONS OF MATTER may be divided into two kinds, primary and secondary. The secondary motions are those, which are given to or received from other matter in motion. Their laws have been successfully investigated by philosophers in their treatises on mechanic powers. These motions are distinguished by this circumstance, that the velocity multiplied into the quantity of matter of the body acted upon is equal to the velocity multiplied into the quantity of matter of the acting body. The primary motions of matter may be divided into three classes, those belonging to gravitation, to chemistry, and to life; and each class has its peculiar laws. Though these three classes include the motions of solid, liquid, and aerial bodies; there is nevertheless a fourth division of motions; I mean those of the supposed ethereal fluids of magnetism, electricity, heat, and light; whose properties are not so well investigated as to be classed with sufficient accuracy. _1st._ The gravitating motions include the annual and diurnal rotation of the earth and planets, the flux and reflux of the ocean, the descent of heavy bodies, and other phænomena of gravitation. The unparalleled sagacity of the great NEWTON has deduced the laws of this class of motions from the simple principle of the general attraction of matter. These motions are distinguished by their tendency to or from the centers of the sun or planets. _2d._ The chemical class of motions includes all the various appearances of chemistry. Many of the facts, which belong to these branches of science, are nicely ascertained, and elegantly classed; but their laws have not yet been developed from such simple principles as those above-mentioned; though it is probable, that they depend on the specific attractions belonging to the particles of bodies, or to the difference of the quantity of attraction belonging to the sides and angles of those particles. The chemical motions are distinguished by their being generally attended with an evident decomposition or new combination of the active materials. _3d._ The third class includes all the motions of the animal and vegetable world; as well those of the vessels, which circulate their juices, and of the muscles, which perform their locomotion, as those of the organs of sense, which constitute their ideas. This last class of motion is the subject of the following pages; which, though conscious of their many imperfections, I hope may give some pleasure to the patient reader, and contribute something to the knowledge and to the cure of diseases. * * * * * SECT. II. EXPLANATIONS AND DEFINITIONS. I. _Outline of the animal economy._--II. 1. _Of the sensorium._ 2. _Of the brain and nervous medulla._ 3. _A nerve._ 4. _A muscular fibre._ 5. _The immediate organs of sense._ 6. _The external organs of sense._ 7. _An idea or sensual motion._ 8. _Perception._ 9. _Sensation._ 10. _Recollection and suggestion._ 11. _Habit, causation, association, catenation._ 12. _Reflex ideas._ 13. _Stimulus defined._ * * * * * As some explanations and definitions will be necessary in the prosecution of the work, the reader is troubled with them in this place, and is intreated to keep them in his mind as he proceeds, and to take them for granted, till an apt opportunity occurs to evince their truth; to which I shall premise a very short outline of the animal economy. * * * * * I.--1. The nervous system has its origin from the brain, and is distributed to every part of the body. Those nerves, which serve the senses, principally arise from that part of the brain, which is lodged in the head; and those, which serve the purposes of muscular motion, principally arise from that part of the brain, which is lodged in the neck and back, and which is erroneously called the spinal marrow. The ultimate fibrils of these nerves terminate in the immediate organs of sense and muscular fibres, and if a ligature be put on any part of their passage from the head or spine, all motion and perception cease in the parts beneath the ligature. 2. The longitudinal muscular fibres compose the locomotive muscles, whose contractions move the bones of the limbs and trunk, to which their extremities are attached. The annular or spiral muscular fibres compose the vascular muscles, which constitute the intestinal canal, the arteries, veins, glands, and absorbent vessels. 3. The immediate organs of sense, as the retina of the eye, probably consist of moving fibrils, with a power of contraction similar to that of the larger muscles above described. 4. The cellular membrane consists of cells, which resemble those of a sponge, communicating with each other, and connecting together all the other parts of the body. 5. The arterial system consists of the aortal and the pulmonary artery, which are attended through their whole course with their correspondent veins. The pulmonary artery receives the blood from the right chamber of the heart, and carries it to the minute extensive ramifications of the lungs, where it is exposed to the action of the air on a surface equal to that of the whole external skin, through the thin moist coats of those vessels, which are spread on the air-cells, which constitute the minute terminal ramifications of the wind-pipe. Here the blood changes its colour from a dark red to a bright scarlet. It is then collected by the branches of the pulmonary vein, and conveyed to the left chamber of the heart. 6. The aorta is another large artery, which receives the blood from the left chamber of the heart, after it has been thus aerated in the lungs, and conveys it by ascending and descending branches to every other part of the system; the extremities of this artery terminate either in glands, as the salivary glands, lacrymal glands, &c. or in capillary vessels, which are probably less involuted glands; in these some fluid, as saliva, tears, perspiration, are separated from the blood; and the remainder of the blood is absorbed or drank up by branches of veins correspondent to the branches of the artery; which are furnished with valves to prevent its return; and is thus carried back, after having again changed its colour to a dark red, to the right chamber of the heart. The circulation of the blood in the liver differs from this general system; for the veins which drink up the refluent blood from those arteries, which are spread on the bowels and mesentery, unite into a trunk in the liver, and form a kind of artery, which is branched into the whole substance of the liver, and is called the vena portarum; and from which the bile is separated by the numerous hepatic glands, which constitute that viscus. 7. The glands may be divided into three systems, the convoluted glands, such as those above described, which separate bile, tears, saliva, &c. Secondly, the glands without convolution, as the capillary vessels, which unite the terminations of the arteries and veins; and separate both the mucus, which lubricates the cellular membrane, and the perspirable matter, which preserves the skin moist and flexible. And thirdly, the whole absorbent system, consisting of the lacteals, which open their mouths into the stomach and intestines, and of the lymphatics, which open their mouths on the external surface of the body, and on the internal linings of all the cells of the cellular membrane, and other cavities of the body. These lacteal and lymphatic vessels are furnished with numerous valves to prevent the return of the fluids, which they absorb, and terminate in glands, called lymphatic glands, and may hence be considered as long necks or mouths belonging to these glands. To these they convey the chyle and mucus, with a part of the perspirable matter, and atmospheric moisture; all which, after having passed through these glands, and having suffered some change in them, are carried forward into the blood, and supply perpetual nourishment to the system, or replace its hourly waste. 8. The stomach and intestinal canal have a constant vermicular motion, which carries forwards their contents, after the lacteals have drank up the chyle from them; and which is excited into action by the stimulus of the aliment we swallow, but which becomes occasionally inverted or retrograde, as in vomiting, and in the iliac passion. II. 1. The word _sensorium_ in the following pages is designed to express not only the medullary part of the brain, spinal marrow, nerves, organs of sense, and of the muscles; but also at the same time that living principle, or spirit of animation, which resides throughout the body, without being cognizable to our senses, except by its effects. The changes which occasionally take place in the sensorium, as during the exertions of volition, or the sensations of pleasure or pain, are termed _sensorial motions_. 2. The similarity of the texture of the brain to that of the pancreas, and some other glands of the body, has induced the inquirers into this subject to believe, that a fluid, perhaps much more subtile than the electric aura, is separated from the blood by that organ for the purposes of motion and sensation. When we recollect, that the electric fluid itself is actually accumulated and given out voluntarily by the torpedo and the gymnotus electricus, that an electric shock will frequently stimulate into motion a paralytic limb, and lastly that it needs no perceptible tubes to convey it, this opinion seems not without probability; and the singular figure of the brain and nervous system seems well adapted to distribute it over every part of the body. For the medullary substance of the brain not only occupies the cavities of the head and spine, but passes along the innumerable ramifications of the nerves to the various muscles and organs of sense. In these it lays aside its coverings, and is intermixed with the slender fibres, which constitute those muscles and organs of sense. Thus all these distant ramifications of the sensorium are united at one of their extremities, that is, in the head and spine; and thus these central parts of the sensorium constitute a communication between all the organs of sense and muscles. 3. A _nerve_ is a continuation of the medullary substance of the brain from the head or spine towards the other parts of the body, wrapped in its proper membrane. 4. The _muscular fibres_ are moving organs intermixed with that medullary substance, which is continued along the nerves, as mentioned above. They are indued with the power of contraction, and are again elongated either by antagonist muscles, by circulating fluids, or by elastic ligaments. So the muscles on one side of the forearm bend the fingers by means of their tendons, and those on the other side of the fore-arm extend them again. The arteries are distended by the circulating blood; and in the necks of quadrupeds there is a strong elastic ligament, which assists the muscles, which elevate the head, to keep it in its horizontal position, and to raise it after it has been depressed. 5. The _immediate organs of sense_ consist in like manner of moving fibres enveloped in the medullary substance above mentioned; and are erroneously supposed to be simply an expansion of the nervous medulla, as the retina of the eye, and the rete mucosum of the skin, which are the immediate organs of vision, and of touch. Hence when we speak of the contractions of the fibrous parts of the body, we shall mean both the contractions of the muscles, and those of the immediate organs of sense. These _fibrous motions_ are thus distinguished from the _sensorial motions_ above mentioned. 6. The _external organs_ of sense are the coverings of the immediate organs of sense, and are mechanically adapted for the reception or transmission of peculiar bodies, or of their qualities, as the cornea and humours of the eye, the tympanum of the ear, the cuticle of the fingers and tongue. 7. The word _idea_ has various meanings in the writers of metaphysic: it is here used simply for those notions of external things, which our organs of sense bring us acquainted with originally; and is defined a contraction, or motion, or configuration, of the fibres, which constitute the immediate organ of sense; which will be explained at large in another part of the work. Synonymous with the word idea, we shall sometimes use the words _sensual motion_ in contradistinction to _muscular motion_. 8. The word _perception_ includes both the action of the organ of sense in consequence of the impact of external objects, and our attention to that action; that is, it expresses both the motion of the organ of sense, or idea, and the pain or pleasure that succeeds or accompanies it. 9. The pleasure or pain which necessarily accompanies all those perceptions or ideas which we attend to, either gradually subsides, or is succeeded by other fibrous motions. In the latter case it is termed _sensation_, as explained in Sect. V. 2, and VI. 2.--The reader is intreated to keep this in his mind, that through all this treatise the word sensation is used to express pleasure or pain only in its active state, by whatever means it is introduced into the system, without any reference to the stimulation of external objects. 10. The vulgar use of the word _memory_ is too unlimited for our purpose: those ideas which we voluntarily recall are here termed ideas of _recollection_, as when we will to repeat the alphabet backwards. And those ideas which are suggested to us by preceding ideas are here termed ideas of _suggestion_, as whilst we repeat the alphabet in the usual order; when by habits previously acquired B is suggested by A, and C by B, without any effort of deliberation. 11. The word _association_ properly signifies a society or convention of things in some respects similar to each other. We never say in common language, that the effect is associated with the cause, though they necessarily accompany or succeed each other. Thus the contractions of our muscles and organs of sense may be said to be associated together, but cannot with propriety be said to be associated with irritations, or with volition, or with sensation; because they are caused by them, as mentioned in Sect. IV. When fibrous contractions succeed other fibrous contractions, the connection is termed _association_; when fibrous contractions succeed sensorial motions, the connection is termed _causation_; when fibrous and sensorial motions reciprocally introduce each other in progressive trains or tribes, it is termed _catenation_ of animal motions. All these connections are said to be produced by _habit_; that is, by frequent repetition. 12. It may be proper to observe, that by the unavoidable idiom of our language the ideas of perception, of recollection, or of imagination, in the plural number signify the ideas belonging to perception, to recollection, or to imagination; whilst the idea of perception, of recollection, or of imagination, in the singular number is used for what is termed "a reflex idea of any of those operations of the sensorium." 13. By the word _stimulus_ is not only meant the application of external bodies to our organs of sense and muscular fibres, which excites into action the sensorial power termed irritation; but also pleasure or pain, when they excite into action the sensorial power termed sensation; and desire or aversion, when they excite into action the power of volition; and lastly, the fibrous contractions which precede association; as is further explained in Sect. XII. 2. 1. * * * * * SECT. III. THE MOTIONS OF THE RETINA DEMONSTRATED BY EXPERIMENTS. I. _Of animal motions and of ideas._ II. _The fibrous structure of the retina._ III. _The activity of the retina in vision._ 1. _Rays of light have no momentum._ 2. _Objects long viewed become fainter._ 3. _Spectra of black objects become luminous._ 4. _Varying spectra from gyration._ 5. _From long inspection of various colours._ IV. _Motions of the organs of sense constitute ideas._ 1. _Light from pressing the eye-ball, and sound from the pulsation of the carotid artery._ 2. _Ideas in sleep mistaken for perceptions._ 3. _Ideas of imagination produce pain and sickness like sensations._ 4. _When the organ of sense is destroyed, the ideas belonging to that sense perish._ V. _Analogy between muscular motions and sensual motions, or ideas._ 1. _They are both originally excited by irritations._ 2. _And associated together in the same manner._ 3. _Both act in nearly the same times._ 4. _Are alike strengthened or fatigued by exercise._ 5. _Are alike painful from inflammation._ 6. _Are alike benumbed by compression._ 7. _Are alike liable to paralysis._ 8. _To convulsion._ 9. _To the influence of old age._--VI. _Objections answered._ 1. _Why we cannot invent new ideas._ 2. _If ideas resemble external objects._ 3. _Of the imagined sensation in an amputated limb._ 4. _Abstract ideas._--VII. _What are ideas, if they are not animal motions?_ Before the great variety of animal motions can be duly arranged into natural classes and orders, it is necessary to smooth the way to this yet unconquered field of science, by removing some obstacles which thwart our passage. I. To demonstrate that the retina and other immediate organs of sense possess a power of motion, and that these motions constitute our ideas, according to the fifth and seventh of the preceding assertions, claims our first attention. Animal motions are distinguished from the communicated motions, mentioned in the first section, as they have no mechanical proportion to their cause; for the goad of a spur on the skin of a horse shall induce him to move a load of hay. They differ from the gravitating motions there mentioned as they are exerted with equal facility in all directions, and they differ from the chemical class of motions, because no apparent decompositions or new combinations are produced in the moving materials. Hence, when we say animal motion is excited by irritation, we do not mean that the motion bears any proportion to the mechanical impulse of the stimulus; nor that it is affected by the general gravitation of the two bodies; nor by their chemical properties, but solely that certain animal fibres are excited into action by something external to the moving organ. In this sense the stimulus of the blood produces the contractions of the heart; and the substances we take into our stomach and bowels stimulate them to perform their necessary functions. The rays of light excite the retina into animal motion by their stimulus; at the same time that those rays of light themselves are physically converged to a focus by the inactive humours of the eye. The vibrations of the air stimulate the auditory nerve into animal action; while it is probable that the tympanum of the ear at the same time undergoes a mechanical vibration. To render this circumstance more easy to be comprehended, _motion may be defined to be a variation of figure_; for the whole universe may be considered as one thing possessing a certain figure; the motions of any of its parts are a variation of this figure of the whole: this definition of motion will be further explained in Section XIV. 2. 2. on the production of ideas. Now the motions of an organ of sense are a succession of configurations of that organ; these configurations succeed each other quicker or slower; and whatever configuration of this organ of sense, that is, whatever portion of the motion of it is, or has usually been, attended to, constitutes an idea. Hence the configuration is not to be considered as an effect of the motion of the organ, but rather as a part or temporary termination of it; and that, whether a pause succeeds it, or a new configuration immediately takes place. Thus when a succession of moving objects are presented to our view, the ideas of trumpets, horns, lords and ladies, trains and canopies, are configurations, that is, parts or links of the successive motions of the organ of vision. [Illustration: Plate I.] These motions or configurations of the organs of sense differ from the sensorial motions to be described hereafter, as they appear to be simply contractions of the fibrous extremities of those organs, and in that respect exactly resemble the motions or contractions of the larger muscles, as appears from the following experiment. Place a circular piece of red silk about an inch in diameter on a sheet of white paper in a strong light, as in Plate I.--look for a minute on this area, or till the eye becomes somewhat fatigued, and then, gently closing your eyes, and shading them with your hand, a circular green area of the same apparent diameter becomes visible in the closed eye. This green area is the colour reverse to the red area, which had been previously inspected, as explained in the experiments on ocular spectra at the end of the work, and in Botanical Garden, P. 1. additional note, No. 1. Hence it appears, that a part of the retina, which had been fatigued by contraction in one direction, relieves itself by exerting the antagonist fibres, and producing a contraction in an opposite direction, as is common in the exertions of our muscles. Thus when we are tired with long action of our arms in one direction, as in holding a bridle on a journey, we occasionally throw them into an opposite position to relieve the fatigued muscles. Mr. Locke has defined an idea to be "whatever is present to the mind;" but this would include the exertions of volition, and the sensations of pleasure and pain, as well as those operations of our system, which acquaint us with external objects; and is therefore too unlimited for our purpose. Mr. Lock seems to have fallen into a further error, by conceiving, that the mind could form a general or abstract idea by its own operation, which was the copy of no particular perception; as of a triangle in general, that was neither acute, obtuse, nor right angled. The ingenious Dr. Berkley and Mr. Hume have demonstrated, that such general ideas have no existence in nature, not even in the mind of their celebrated inventor. We shall therefore take for granted at present, that our recollection or imagination of external objects consists of a partial repetition of the perceptions, which were excited by those external objects, at the time we became acquainted with them; and that our reflex ideas of the operations of our minds are partial repetitions of those operations. II. The following article evinces that the organ of vision consists of a fibrous part as well as of the nervous medulla, like other white muscles; and hence, as it resembles the muscular parts of the body in its structure, we may conclude, that it must resemble them in possessing a power of being excited into animal motion.--The subsequent experiments on the optic nerve, and on the colours remaining in the eye, are copied from a paper on ocular spectra published in the seventy-sixth volume of the Philos. Trans. by Dr. R. Darwin of Shrewsbury; which, as I shall have frequent occasion to refer to, is reprinted in this work, Sect. XL. The retina of an ox's eye was suspended in a glass of warm water, and forcibly torn in a few places; the edges of these parts appeared jagged and hairy, and did not contract and become smooth like simple mucus, when it is distended till it breaks; which evinced that it consisted of fibres. This fibrous construction became still more distinct to the light by adding some caustic alcali to the water; as the adhering mucus was first eroded, and the hair-like fibres remained floating in the vessel. Nor does the degree of transparency of the retina invalidate this evidence of its fibrous structure, since Leeuwenhoek has shewn, that the crystalline humour itself consists of fibres. Arc. Nat. V. I. 70. Hence it appears, that as the muscles consist of larger fibres intermixed with a smaller quantity of nervous medulla, the organ of vision consists of a greater quantity of nervous medulla intermixed with smaller fibres. It is probable that the locomotive muscles of microscopic animals may have greater tenuity than these of the retina; and there is reason to conclude from analogy, that the other immediate organs of sense, as the portio mollis of the auditory nerve, and the rete mucosum of the skin, possess a similarity of structure with the retina, and a similar power of being excited into animal motion. III. The subsequent articles shew, that neither mechanical impressions, nor chemical combinations of light, but that the animal activity of the retina constitutes vision. 1. Much has been conjectured by philosophers about the momentum of the rays of light; to subject this to experiment a very light horizontal balance was constructed by Mr. Michel, with about an inch square of thin leaf-copper suspended at each end of it, as described in Dr. Priestley's History of Light and Colours. The focus of a very large convex mirror was thrown by Dr. Powel, in his lectures on experimental philosophy, in my presence, on one wing of this delicate balance, and it receded from the light; thrown on the other wing, it approached towards the light, and this repeatedly; so that no sensible impulse could be observed, but what might well be ascribed to the ascent of heated air. Whence it is reasonable to conclude, that the light of the day must be much too weak in its dilute state to make any mechanical impression on so tenacious a substance as the retina of the eye.--Add to this, that as the retina is nearly transparent, it could therefore make less resistance to the mechanical impulse of light; which, according, to the observations related by Mr. Melvil in the Edinburgh Literary Essays, only communicates heat, and should therefore only communicate momentum, where it is obstructed, reflected, or refracted.--From whence also may be collected the final cause of this degree of transparency of the retina, viz. left by the focus of stronger lights, heat and pain should have been produced in the retina, instead of that stimulus which excites it into animal motion. 2. On looking long on an area of scarlet silk of about an inch in diameter laid on white paper, as in Plate I. the scarlet colour becomes fainter, till at length it entirely vanishes, though the eye is kept uniformly and steadily upon it. Now if the change or motion of the retina was a mechanical impression, or a chemical tinge of coloured light, the perception would every minute become stronger and stronger,--whereas in this experiment it becomes every instant weaker and weaker. The same circumstance obtains in the continued application of sound, or of sapid bodies, or of odorous ones, or of tangible ones, to their adapted organs of sense. [Illustration: Plate II.] Thus when a circular coin, as a shilling, is pressed on the palm of the hand, the sense of touch is mechanically compressed; but it is the stimulus of this pressure that excites the organ of touch into animal action, which constitutes the perception of hardness and of figure; for in some minutes the perception ceases, though the mechanical pressure of the object remains. 3. Make with ink on white paper a very black spot about half an inch in diameter, with a tail about an inch in length, so as to resemble a tadpole, as in Plate II.; look steadfastly for a minute on the center of this spot, and, on moving the eye a little, the figure of the tadpole will be seen on the white part of the paper; which figure of the tadpole will appear more luminous than the other part of the white paper; which can only be explained by supposing that a part of the retina, on which the tadpole was delineated, to have become more sensible to light than the other parts of it, which were exposed to the white paper; and not from any idea of mechanical impression or chemical combination of light with the retina. 4. When any one turns round rapidly, till he becomes dizzy, and falls upon the ground, the spectra of the ambient objects continue to present themselves in rotation, and he seems to behold the objects still in motion. Now if these spectra were impressions on a passive organ, they either must continue as they were received last, or not continue at all. 5. Place a piece of red silk about an inch in diameter on a sheet of white paper in a strong light, as in Plate I; look steadily upon it from the distance of about half a yard for a minute; then closing your eye-lids, cover them with your hands and handkerchief, and a green spectrum will be seen in your eyes resembling in form the piece of red silk. After some seconds of time the spectrum will disappear, and in a few more seconds will reappear; and thus alternately three or four times, if the experiment be well made, till at length it vanishes entirely. [Illustration: Plate III.] 6. Place a circular piece of white paper, about four inches in diameter, in the sunshine, cover the center of this with a circular piece of black silk, about three inches in diameter; and the center of the black silk with a circle of pink silk, about two inches in diameter; and the center of the pink silk with a circle of yellow silk, about one inch in diameter; and the center of this with a circle of blue silk, about half an inch in diameter; make a small spot with ink in the center of the blue silk, as in Plate III.; look steadily for a minute on this central spot, and then closing your eyes, and applying your hand at about an inch distance before them, so as to prevent too much or too little light from passing through the eye-lids, and you will see the most beautiful circles of colours that imagination can conceive; which are most resembled by the colours occasioned by pouring a drop or two of oil on a still lake in a bright day. But these circular irises of colours are not only different from the colours of the silks above mentioned, but are at the same time perpetually changing as long as they exist. From all these experiments it appears, that these spectra in the eye are not owing to the mechanical impulse of light impressed on the retina; nor to its chemical combination with that organ; nor to the absorption and emission of light, as is supposed, perhaps erroneously, to take place in calcined shells and other phosphorescent bodies, after having been exposed to the light: for in all these cases the spectra in the eye should either remain of the same colour, or gradually decay, when the object is withdrawn; and neither their evanescence during the presence of their object, as in the second experiment, nor their change from dark to luminous, as in the third experiment, nor their rotation, as in the fourth experiment, nor the alternate presence and evanescence of them, as in the fifth experiment, nor the perpetual change of colours of them, as in the last experiment, could exist. IV. The subsequent articles shew, that these animal motions or configurations of our organs of sense constitute our ideas. 1. If any one in the dark presses the ball of his eye, by applying his finger to the external corner of it, a luminous appearance is observed; and by a smart stroke on the eye great slashes of fire are perceived. (Newton's Optics.) So that when the arteries, that are near the auditory nerve, make stronger pulsations than usual, as in some fevers, an undulating sound is excited in the ears. Hence it is not the presence of the light and sound, but the motions of the organ, that are immediately necessary to constitute the perception or idea of light and sound. 2. During the time of sleep, or in delirium, the ideas of imagination are mistaken for the perceptions of external objects; whence it appears, that these ideas of imagination, are no other than a reiteration of those motions of the organs of sense, which were originally excited by the stimulus of external objects: and in our waking hours the simple ideas, that we call up by recollection or by imagination, as the colour of red, or the smell of a rose, are exact resemblances of the same simple ideas from perception; and in consequence must be a repetition of those very motions. 3. The disagreeable sensation called the tooth-edge is originally excited by the painful jarring of the teeth in biting the edge of the glass, or porcelain cup, in which our food was given us in our infancy, as is further explained in the Section XVI. 10, on Instinct.--This disagreeable sensation is afterwards excitable not only by a repetition of the sound, that was then produced, but by imagination alone, as I have myself frequently experienced; in this case the idea of biting a china cup, when I imagine it very distinctly, or when I see another person bite a cup or glass, excites an actual pain in the nerves of my teeth. So that this idea and pain seem to be nothing more than the reiterated motions of those nerves, that were formerly so disagreeably affected. Other ideas that are excited by imagination or recollection in many instances produce similar effects on the constitution, as our perceptions had formerly produced, and are therefore undoubtedly a repetition of the same motions. A story which the celebrated Baron Van Swieton relates of himself is to this purpose. He was present when the putrid carcase of a dead dog exploded with prodigious stench; and some years afterwards, accidentally riding along the same road, he was thrown into the same sickness and vomiting by the idea of the stench, as he had before experienced from the perception of it. 4. Where the organ of sense is totally destroyed, the ideas which were received by that organ seem to perish along with it, as well as the power of perception. Of this a satisfactory instance has fallen under my observation. A gentleman about sixty years of age had been totally deaf for near thirty years: he appeared to be a man of good understanding, and amused himself with reading, and by conversing either by the use of the pen, or by signs made with his fingers, to represent letters. I observed that he had so far forgot the pronunciation of the language, that when he attempted to speak, none of his words had distinct articulation, though his relations could sometimes understand his meaning. But, which is much to the point, he assured me, that in his dreams he always imagined that people conversed with him by signs or writing, and never that he heard any one speak to him. From hence it appears, that with the perceptions of sounds he has also lost the ideas of them; though the organs of speech still retain somewhat of their usual habits of articulation. This observation may throw some light on the medical treatment of deaf people; as it may be learnt from their dreams whether the auditory nerve be paralytic, or their deafness be owing to some defect of the external organ. It rarely happens that the immediate organ of vision is perfectly destroyed. The most frequent causes of blindness are occasioned by defects of the external organ, as in cataracts and obfuscations of the cornea. But I have had the opportunity of conversing with two men, who had been some years blind; one of them had a complete gutta serena, and the other had lost the whole substance of his eyes. They both told me that they did not remember to have ever dreamt of visible objects, since the total loss of their sight. V. Another method of discovering that our ideas are animal motions of the organs of sense, is from considering the great analogy they bear to the motions of the larger muscles of the body. In the following articles it will appear that they are originally excited into action by the irritation of external objects like our muscles; are associated together like our muscular motions; act in similar time with them; are fatigued by continued exertion like them; and that the organs of sense are subject to inflammation, numbness, palsy, convulsion, and the defects of old age, in the same manner as the muscular fibres. 1. All our perceptions or ideas of external objects are universally allowed to have been originally excited by the stimulus of those external objects; and it will be shewn in a succeeding section, that it is probable that all our muscular motions, as well those that are become voluntary as those of the heart and glandular system, were originally in like manner excited by the stimulus of something external to the organ of motion. 2. Our ideas are also associated together after their production precisely in the same manner as our muscular motions; which will likewise be fully explained in the succeeding section. 3. The time taken up in performing an idea is likewise much the same as that taken up in performing a muscular motion. A musician can press the keys of an harpsichord with his fingers in the order of a tune he has been accustomed to play, in as little time as he can run over those notes in his mind. So we many times in an hour cover our eye-balls with our eye-lids without perceiving that we are in the dark; hence the perception or idea of light is not changed for that of darkness in so small a time as the twinkling of an eye; so that in this case the muscular motion of the eye-lid is performed quicker than the perception of light can be changed for that of darkness.--So if a fire-stick be whirled round in the dark, a luminous circle appears to the observer; if it be whirled somewhat slower, this circle becomes interrupted in one part; and then the time taken up in such a revolution of the stick is the same that the observer uses in changing his ideas: thus the [Greek: dolikoskoton enkos] of Homer, the long shadow of the flying javelin, is elegantly designed to give us an idea of its velocity, and not of its length. 4. The fatigue that follows a continued attention of the mind to one object is relieved by changing the subject of our thoughts; as the continued movement of one limb is relieved by moving another in its stead. Whereas a due exercise of the faculties of the mind strengthens and improves those faculties, whether of imagination or recollection; as the exercise of our limbs in dancing or fencing increases the strength and agility of the muscles thus employed. 5. If the muscles of any limb are inflamed, they do not move without pain; so when the retina is inflamed, its motions also are painful. Hence light is as intolerable in this kind of ophthalmia, as pressure is to the finger in the paronychia. In this disease the patients frequently dream of having their eyes painfully dazzled; hence the idea of strong light is painful as well as the reality. The first of these facts evinces that our perceptions are motions of the organs of sense; and the latter, that our imaginations are also motions of the same organs. 6. The organs of sense, like the moving muscles, are liable to become benumbed, or less sensible, from compression. Thus, if any person on a light day looks on a white wall, he may perceive the ramifications of the optic artery, at every pulsation of it, represented by darker branches on the white wall; which is evidently owing to its compressing the retina during the diastole of the artery. Savage Nosolog. 7. The organs of sense and the moving muscles are alike liable to be affected with palsy, as in the gutta serena, and in some cases of deafness; and one side of the face has sometimes lost its power of sensation, but retained its power of motion; other parts of the body have lost their motions but retained their sensation, as in the common hemiplagia; and in other instances both these powers have perished together. 8. In some convulsive diseases a delirium or insanity supervenes, and the convulsions cease; and conversely the convulsions shall supervene, and the delirium cease. Of this I have been a witness many times in a day in the paroxysms of violent epilepsies; which evinces that one kind of delirium is a convulsion of the organs of sense, and that our ideas are the motions of these organs: the subsequent cases will illustrate this observation. Miss G----, a fair young lady, with light eyes and hair, was seized with most violent convulsions of her limbs, with outrageous hiccough, and most vehement efforts to vomit: after near an hour was elapsed this tragedy ceased, and a calm talkative delirium supervened for about another hour; and these relieved each other at intervals during the greatest part of three or four days. After having carefully considered this disease, I thought the convulsions of her ideas less dangerous than those of her muscles; and having in vain attempted to make any opiate continue in her stomach, an ounce of laudanum was rubbed along the spine of her back, and a dram of it was used as an enema; by this medicine a kind of drunken delirium was continued many hours; and when it ceased the convulsions did not return; and the lady continued well many years, except some lighter relapses, which were relieved in the same manner. Miss H----, an accomplished young lady, with light eyes and hair, was seized with convulsions of her limbs, with hiccough, and efforts to vomit, more violent than words can express; these continued near an hour, and were succeeded with a cataleptic spasm of one arm, with the hand applied to her head; and after about twenty minutes these spasms ceased, and a talkative reverie supervened for near an other hour, from which no violence, which it was proper to use, could awaken her. These periods of convulsions, first of the muscles, and then of the ideas, returned twice a day for several weeks; and were at length removed by great doses of opium, after a great variety of other medicines and applications had been in vain experienced. This lady was subject to frequent relapses, once or twice a year for many years, and was as frequently relieved by the same method. Miss W----, an elegant young lady, with black eyes and hair, had sometimes a violent pain of her side, at other times a most painful strangury, which were every day succeeded by delirium; which gave a temporary relief to the painful spasms. After the vain exhibition of variety of medicines and applications by different physicians, for more than a twelvemonth, she was directed to take some doses of opium, which were gradually increased, by which a drunken delirium was kept up for a day or two, and the pains prevented from returning. A flesh diet, with a little wine or beer, instead of the low regimen she had previously used, in a few weeks completely established her health; which, except a few relapses, has continued for many years. 9. Lastly, as we advance in life all the parts of the body become more rigid, and are rendered less susceptible of new habits of motion, though they retain those that were before established. This is sensibly observed by those who apply themselves late in life to music, fencing, or any of the mechanic arts. In the same manner many elderly people retain the ideas they had learned early in life, but find great difficulty in acquiring new trains of memory; insomuch that in extreme old age we frequently see a forgetfulness of the business of yesterday, and at the same time a circumstantial remembrance of the amusements of their youth; till at length the ideas of recollection and activity of the body gradually cease together,--such is the condition of humanity!--and nothing remains but the vital motions and sensations. VI. 1. In opposition to this doctrine of the production of our ideas, it may be asked, if some of our ideas, like other animal motions, are voluntary, why can we not invent new ones, that have not been received by perception? The answer will be better understood after having perused the succeeding section, where it will be explained, that the muscular motions likewise are originally excited by the stimulus of bodies external to the moving organ; and that the will has only the power of repeating the motions thus excited. 2. Another objector may ask, Can the motion of an organ of sense resemble an odour or a colour? To which I can only answer, that it has not been demonstrated that any of our ideas resemble the objects that excite them; it has generally been believed that they do not; but this shall be discussed at large in Sect. XIV. 3. There is another objection that at first view would seem less easy to surmount. After the amputation, of a foot or a finger, it has frequently happened, that an injury being offered to the stump of the amputated limb, whether from cold air, too great pressure, or other accidents, the patient has complained, of a sensation of pain in the foot or finger, that was cut off. Does not this evince that all our ideas are excited in the brain, and not in the organs of sense? This objection is answered, by observing that our ideas of the shape, place, and solidity of our limbs, are acquired by our organs of touch and of sight, which are situated in our fingers and eyes, and not by any sensations in the limb itself. In this case the pain or sensation, which formerly has arisen in the foot or toes, and been propagated along the nerves to the central part of the sensorium, was at the same time accompanied with a visible idea of the shape and place, and with a tangible idea of the solidity of the affected limb: now when these nerves are afterwards affected by any injury done to the remaining stump with a similar degree or kind of pain, the ideas of the shape, place, or solidity of the lost limb, return by association; as these ideas belong to the organs of sight and touch, on which they were first excited. 4. If you wonder what organs of sense can be excited into motion, when you call up the ideas of wisdom or benevolence, which Mr. Locke has termed abstracted ideas; I ask you by what organs of sense you first became acquainted with these ideas? And the answer will be reciprocal; for it is certain that all our ideas were originally acquired by our organs of sense; for whatever excites our perception must be external to the organ that perceives it, and we have no other inlets to knowledge but by our perceptions: as will be further explained in Section XIV. and XV. on the Productions and Classes of Ideas. VII. If our recollection or imagination be not a repetition of animal movements, I ask, in my turn, What is it? You tell me it consists of images or pictures of things. Where is this extensive canvas hung up? or where are the numerous receptacles in which those are deposited? or to what else in the animal system have they any similitude? That pleasing picture of objects, represented in miniature on the retina of the eye, seems to have given rise to this illusive oratory! It was forgot that this representation belongs rather to the laws of light, than to those of life; and may with equal elegance be seen in the camera obscura as in the eye; and that the picture vanishes for ever, when the object is withdrawn. * * * * * SECT. IV. LAWS OF ANIMAL CAUSATION. I. The fibres, which constitute the muscles and organs of sense, possess a power of contraction. The circumstances attending the exertion of this power of CONTRACTION constitute the laws of animal motion, as the circumstances attending the exertion of the power of ATTRACTION constitute the laws of motion of inanimate matter. II. The spirit of animation is the immediate cause of the contraction of animal fibres, it resides in the brain and nerves, and is liable to general or partial diminution or accumulation. III. The stimulus of bodies external to the moving organ is the remote cause of the original contractions of animal fibres. IV. A certain quantity of stimulus produces irritation, which is an exertion of the spirit of animation exciting the fibres into contraction. V. A certain quantity of contraction of animal fibres, if it be perceived at all, produces pleasure; a greater or less quantity of contraction, if it be perceived at all, produces pain; these constitute sensation. VI. A certain quantity of sensation produces desire or aversion; these constitute volition. VII. All animal motions which have occurred at the same time, or in immediate succession, become so connected, that when one of them is reproduced, the other has a tendency to accompany or succeed it. When fibrous contractions succeed or accompany other fibrous contractions, the connection is termed association; when fibrous contractions succeed sensorial motions, the connexion is termed causation; when fibrous and sensorial motions reciprocally introduce each other, it is termed catenation of animal motions. All these connections are said to be produced by habit, that is, by frequent repetition. These laws of animal causation will be evinced by numerous facts, which occur in our daily exertions; and will afterwards be employed to explain the more recondite phænomena of the production, growth, diseases, and decay of the animal system. * * * * * SECT. V. OF THE FOUR FACULTIES OR MOTIONS OF THE SENSORIUM. 1. _Four sensorial powers._ 2. _Irritation, sensation, volition, association defined._ 3. _Sensorial motions distinguished from fibrous motions._ 1. The spirit of animation has four different modes of action, or in other words the animal sensorium possesses four different faculties, which are occasionally exerted, and cause all the contractions of the fibrous parts of the body. These are the faculty of causing fibrous contractions in consequence of the irritations excited by external bodies, in consequence of the sensations of pleasure or pain, in consequence of volition, and in consequence of the associations of fibrous contractions with other fibrous contractions, which precede or accompany them. These four faculties of the sensorium during their inactive state are termed irritability, sensibility, voluntarity, and associability; in their active state they are termed as above, irritation, sensation, volition, association. 2. IRRITATION is an exertion or change of some extreme part of the sensorium residing in the muscles or organs of sense, in consequence of the appulses of external bodies. SENSATION is an exertion or change of the central parts of the sensorium, or of the whole of it, _beginning_ at some of those extreme parts of it, which reside in the muscles or organs of sense. VOLITION is an exertion or change of the central parts of the sensorium, or of the whole of it, _terminating_ in some of those extreme parts of it, which reside in the muscles or organs of sense. ASSOCIATION is an exertion or change of some extreme part of the sensorium residing in the muscles or organs of sense, in consequence of some antecedent or attendant fibrous contractions. 3. These four faculties of the animal sensorium may at the time of their exertions be termed motions without impropriety of language; for we cannot pass from a state of insensibility or inaction to a state of sensibility or of exertion without some change of the sensorium, and every change includes motion. We shall therefore sometimes term the above described faculties _sensorial motions_ to distinguish them from _fibrous motions_; which latter expression includes the motions of the muscles and organs of sense. The active motions of the fibres, whether those of the muscles or organs of sense, are probably simple contractions; the fibres being again elongated by antagonist muscles, by circulating fluids, or sometimes by elastic ligaments, as in the necks of quadrupeds. The sensorial motions, which constitute the sensations of pleasure or pain, and which constitute volition, and which cause the fibrous contractions in consequence of irritation or of association, are not here supposed to be fluctuations or refluctuations of the spirit of animation; nor are they supposed to be vibrations or revibrations, nor condensations or equilibrations of it; but to be changes or motions of it peculiar to life. * * * * * SECT. VI. OF THE FOUR CLASSES OF FIBROUS MOTIONS. I. _Origin of fibrous contractions._ II. _Distribution of them into four classes, irritative motions, sensitive motions, voluntary motions, and associate motions, defined._ I. All the fibrous contractions of animal bodies originate from the sensorium, and resolve themselves into four classes, correspondent with the four powers or motions of the sensorium above described, and from which they have their causation. 1. These fibrous contractions were originally caused by the irritations excited by objects, which are external to the moving organ. As the pulsations of the heart are owing to the irritations excited by the stimulus of the blood; and the ideas of perception are owing to the irritations excited by external bodies. 2. But as painful or pleasurable sensations frequently accompanied those irritations, by habit these fibrous contractions became causeable by the sensations, and the irritations ceased to be necessary to their production. As the secretion of tears in grief is caused by the sensation of pain; and the ideas of imagination, as in dreams or delirium, are excited by the pleasure or pain, with which they were formerly accompanied. 3. But as the efforts of the will frequently accompanied these painful or pleasureable sensations, by habit the fibrous contractions became causable by volition; and both the irritations and sensations ceased to be necessary to their production. As the deliberate locomotions of the body, and the ideas of recollection, as when we will to repeat the alphabet backwards. 4. But as many of these fibrous contractions frequently accompanied other fibrous contractions, by habit they became causable by their associations with them; and the irritations, sensations, and volition, ceased to be necessary to their production. As the actions of the muscles of the lower limbs in fencing are associated with those of the arms; and the ideas of suggestion are associated with other ideas, which precede or accompany them; as in repeating carelessly the alphabet in its usual order after having began it. II. We shall give the following names to these four classes of fibrous motions, and subjoin their definitions. 1. Irritative motions. That exertion or change of the sensorium, which is caused by the appulses of external bodies, either simply subsides, or is succeeded by sensation, or it produces fibrous motions; it is termed irritation, and irritative motions are those contractions of the muscular fibres, or of the organs of sense, that are immediately consequent to this exertion or change of the sensorium. 2. Sensitive motions. That exertion or change of the sensorium, which constitutes pleasure or pain, either simply subsides, or is succeeded by volition, or it produces fibrous motions; it is termed sensation, and the sensitive motions are those contractions of the muscular fibres, or of the organs of sense, that are immediately consequent to this exertion or change of the sensorium. 3. Voluntary motions. That exertion or change of the sensorium, which constitutes desire or aversion, either simply subsides, or is succeeded by fibrous motions; it is then termed volition, and voluntary motions are those contractions of the muscular fibres, or of the organs of sense, that are immediately consequent to this exertion or change of the sensorium. 4. Associate motions. That exertion or change of the sensorium, which accompanies fibrous motions, either simply subsides, or is succeeded by sensation or volition, or it produces other fibrous motions; it is then termed association, and the associate motions are those contractions of the muscular fibres, or of the organs of sense, that are immediately consequent to this exertion or change of the sensorium. * * * * * SECT. VII. OF IRRITATIVE MOTIONS. I. 1. _Some muscular motions are excited by perpetual irritations._ 2. _Others more frequently by sensations._ 3. _Others by volition. Case of involuntary stretchings in paralytic limbs._ 4. _Some sensual motions are excited by perpetual irritations._ 5. _Others more frequently by sensation or volition._ II. 1. _Muscular motions excited by perpetual irritations occasionally become obedient sensation and to volition._ 2. _And the sensual motions._ III. 1. _Other muscular motions are associated with the irritative ones._ 2. _And other ideas with irritative ones. Of letters, language, hieroglyphics. Irritative ideas exist without our attention to them._ I. 1. Many of our muscular motions are excited by perpetual irritations, as those of the heart and arterial system by the circumfluent blood. Many other of them are excited by intermitted irritations, as those of the stomach and bowels by the aliment we swallow; of the bile-ducts by the bile; of the kidneys, pancreas, and many other glands, by the peculiar fluids they separate from the blood; and those of the lacteal and other absorbent vessels by the chyle, lymph, and moisture of the atmosphere. These motions are accelerated or retarded, as their correspondent irritations are increased or diminished, without our attention or consciousness, in the same manner as the various secretions of fruit, gum, resin, wax, and, honey, are produced in the vegetable world, and as the juices of the earth and the moisture of the atmosphere are absorbed by their roots and foliage. 2. Other muscular motions, that are most frequently connected with our sensations, as those of the sphincters of the bladder and anus, and the musculi erectores penis, were originally excited into motion by irritation, for young children make water, and have other evacuations without attention to these circumstances; "et primis etiam ab incunabulis tenduntur sæpius puerorum penes, amore nondum expergefacto." So the nipples of young women are liable to become turgid by irritation, long before they are in a situation to be excited by the pleasure of giving milk to the lips of a child. 3. The contractions of the larger muscles of our bodies, that are most frequently connected with volition, were originally excited into action by internal irritations: as appears from the stretching or yawning of all animals after long sleep. In the beginning of some fevers this irritation of the muscles produces perpetual stretching and yawning; in other periods of fever an universal restlessness arises from the same cause, the patient changing the attitude of his body every minute. The repeated struggles of the foetus in the uterus must be owing to this internal irritation: for the foetus can have no other inducement to move its limbs but the tædium or irksomeness of a continued posture. The following case evinces, that the motions of stretching the limbs after a continued attitude are not always owing to the power of the will. Mr. Dean, a mason, of Austry in Leicestershire, had the spine of the third vertebra of the back enlarged; in some weeks his lower extremities became feeble, and at length quite paralytic: neither the pain of blisters, the heat of fomentations, nor the utmost efforts of the will could produce the least motion in these limbs; yet twice or thrice a day for many months his feet, legs, and thighs, were affected for many minutes with forceable stretchings, attended with the sensation of fatigue; and he at length recovered the use of his limbs, though the spine continued protuberant. The same circumstance is frequently seen in a less degree in the common hemiplagia; and when this happens, I have believed repeated and strong shocks of electricity to have been of great advantage. 4. In like manner the various organs of sense are originally excited into motion by various external stimuli adapted to this purpose, which motions are termed perceptions or ideas; and many of these motions during our waking hours are excited by perpetual irritation, as those of the organs of hearing and of touch. The former by the constant low indistinct noises that murmur around us, and the latter by the weight of our bodies on the parts which support them; and by the unceasing variations of the heat, moisture, and pressure of the atmosphere; and these sensual motions, precisely as the muscular ones above mentioned, obey their correspondent irritations without our attention or consciousness. 5. Other classes of our ideas are more frequently excited by our sensations of pleasure or pain, and others by volition: but that these have all been originally excited by stimuli from external objects, and only vary in their combinations or reparations, has been fully evinced by Mr. Locke: and are by him termed the ideas of perception in contradistinction to those, which he calls the ideas of reflection. II. 1. These muscular motions, that are excited by perpetual irritation, are nevertheless occasionally excitable by the sensations of pleasure or pain, or by volition; as appears by the palpitation of the heart from fear, the increased secretion of saliva at the sight of agreeable food, and the glow on the skin of those who are ashamed. There is an instance told in the Philosophical Transactions of a man, who could for a time stop the motion of his heart when he pleased; and Mr. D. has often told me, be could so far increase the peristaltic motion of his bowels by voluntary efforts, as to produce an evacuation by stool at any time in half an hour. 2. In like manner the sensual motions, or ideas, that are excited by perpetual irritation, are nevertheless occasionally excited by sensation or volition; as in the night, when we listen under the influence of fear, or from voluntary attention, the motions excited in the organ of hearing by the whispering of the air in our room, the pulsation of our own arteries, or the faint beating of a distant watch, become objects of perception. III. 1. Innumerable trains or tribes of other motions are associated with these muscular motions which are excited by irritation; as by the stimulus of the blood in the right chamber of the heart, the lungs are induced to expand themselves; and the pectoral and intercostal muscles, and the diaphragm, act at the same time by their associations with them. And when the pharinx is irritated by agreeable food, the muscles of deglutition are brought into action by association. Thus when a greater light falls on the eye, the iris is brought into action without our attention; and the ciliary process, when the focus is formed before or behind the retina, by their associations with the increased irritative motions of the organ of vision. Many common actions of life are produced in a similar manner. If a fly settle on my forehead, whilst I am intent on my present occupation, I dislodge it with my finger, without exciting my attention or breaking the train of my ideas. 2. In like manner the irritative ideas suggest to us many other trains or tribes of ideas that are associated with them. On this kind of connection, language, letters, hieroglyphics, and every kind of symbol, depend. The symbols themselves produce irritative ideas, or sensual motions, which we do not attend to; and other ideas, that are succeeded by sensation, are excited by their association with them. And as these irritative ideas make up a part of the chain of our waking thoughts, introducing other ideas that engage our attention, though themselves are unattended to, we find it very difficult to investigate by what steps many of our hourly trains of ideas gain their admittance. It may appear paradoxical, that ideas can exist, and not be attended to; but all our perceptions are ideas excited by irritation, and succeeded by sensation. Now when these ideas excited by irritation give us neither pleasure nor pain, we cease to attend to them. Thus whilst I am walking through that grove before my window, I do not run against the trees or the benches, though my thoughts are strenuously exerted on some other object. This leads us to a distinct knowledge of irritative ideas, for the idea of the tree or bench, which I avoid, exists on my retina, and induces by association the action of certain locomotive muscles; though neither itself nor the actions of those muscles engage my attention. Thus whilst we are conversing on this subject, the tone, note, and articulation of every individual word forms its correspondent irritative idea on the organ of hearing; but we only attend to the associated ideas, that are attached by habit to these irritative ones, and are succeeded by sensation; thus when we read the words "PRINTING-PRESS" we do not attend to the shape, size, or existence of the letters which compose these words, though each of them excites a correspondent irritative motion of our organ of vision, but they introduce by association our idea of the most useful of modern inventions; the capacious reservoir of human knowledge, whose branching streams diffuse sciences, arts, and morality, through all nations and all ages. * * * * * SECT. VIII. OF SENSITIVE MOTIONS. I. 1. _Sensitive muscular motions were originally excited into action by irritation._ 2. _And sensitive sensual motions, ideas of imagination, dreams._ II. 1. _Sensitive muscular motions are occasionally obedient to volition._ 2. _And sensitive sensual motions._ III. 1. _Other muscular motions are associated with the sensitive ones._ 2. _And other sensual motions._ I. 1. Many of the motions of our muscles, that are excited into action by irritation, are at the same time accompanied with painful or pleasurable sensations; and at length become by habit causable by the sensations. Thus the motions of the sphincters of the bladder and anus were originally excited into action by irritation; for young children give no attention to these evacuations; but as soon as they become sensible of the inconvenience of obeying these irritations, they suffer the water or excrement to accumulate, till it disagreeably affects them; and the action of those sphincters is then in consequence of this disagreeable sensation. So the secretion of saliva, which in young children is copiously produced by irritation, and drops from their mouths, is frequently attended with the agreeable sensation produced by the mastication of tasteful food;, till at length the sight of such food to a hungry person excites into action these salival glands; as is seen in the slavering of hungry dogs. The motions of those muscles, which are affected by lascivious ideas, and those which are exerted in smiling, weeping, starting from fear, and winking at the approach of danger to the eye, and at times the actions of every large muscle of the body become causable by our sensations. And all these motions are performed with strength and velocity in proportion to the energy of the sensation that excites them, and the quantity of sensorial power. 2. Many of the motions of our organs of sense, or ideas, that were originally excited into action by irritation, become in like manner more frequently causable by our sensations of pleasure or pain. These motions are then termed the ideas of imagination, and make up all the scenery and transactions of our dreams. Thus when any painful or pleasurable sensations possess us, as of love, anger, fear; whether in our sleep or waking hours, the ideas, that have been formerly excited by the objects of these sensations, now vividly recur before us by their connection with these sensations themselves. So the fair smiling virgin, that excited your love by her presence, whenever that sensation recurs, rises before you in imagination; and that with all the pleasing circumstances, that had before engaged your attention. And in sleep, when you dream under the influence of fear, all the robbers, fires, and precipices, that you formerly have seen or heard of, arise before you with terrible vivacity. All these sensual motions, like the muscular ones above mentioned, are performed with strength and velocity in proportion to the energy of the sensation of pleasure or pain, which excites them, and the quantity of sensorial power. II. 1. Many of these muscular motions above described, that are most frequently excited by our sensations, are nevertheless occasionally causable by volition; for we can smile or frown spontaneously, can make water before the quantity or acrimony of the urine produces a disagreeable sensation, and can voluntarily masticate a nauseous drug, or swallow a bitter draught, though our sensation would strongly dissuade us. 2. In like manner the sensual motions, or ideas, that are most frequently excited by our sensations, are nevertheless occasionally causeable by volition, as we can spontaneously call up our last night's dream before us, tracing it industriously step by step through all its variety of scenery and transaction; or can voluntarily examine or repeat the ideas, that have been excited by out disgust or admiration. III. 1. Innumerable trains or tribes of motions are associated with these sensitive muscular motions above mentioned; as when a drop of water falling into the wind-pipe disagreeably affects the air-vessels of the lungs, they are excited into violent action; and with these sensitive motions are associated the actions of the pectoral and intercostal muscles, and the diaphragm; till by their united and repeated succussions the drop is returned through the larinx. The same occurs when any thing disagreeably affects the nostrils, or the stomach, or the uterus; variety of muscles are excited by association into forcible action, not to be suppressed by the utmost efforts of the will; as in sneezing, vomiting, and parturition. 2. In like manner with these sensitive sensual motions, or ideas of imagination, are associated many other trains or tribes of ideas, which by some writers of metaphysics have been classed under the terms of resemblance, causation, and contiguity; and will be more fully treated of hereafter. * * * * * SECT. IX. OF VOLUNTARY MOTIONS. I. 1. _Voluntary muscular motions are originally excited by irritations._ 2. _And voluntary ideas. Of reason._ II. 1. _Voluntary muscular motions are occasionally causable by sensations._ 2. _And voluntary ideas._ III. 1. _Voluntary muscular motions are occasionally obedient to irritations._ 2. _And voluntary ideas._ IV. 1. _Voluntary muscular motions are associated with other muscular motions._ 2. _And voluntary ideas._ When pleasure or pain affect the animal system, many of its motions both muscular and sensual are brought into action; as was shewn in the preceding section, and were called sensitive motions. The general tendency of these motions is to arrest and to possess the pleasure, or to dislodge or avoid the pain: but if this cannot immediately be accomplished, desire or aversion are produced, and the motions in consequence of this new faculty of the sensorium are called voluntary. I. 1. Those muscles of the body that are attached to bones, have in general their principal connections with volition, as I move my pen or raise my body. These motions were originally excited by irritation, as was explained in the section on that subject, afterwards the sensations of pleasure or pain, that accompanied the motions thus excited, induced a repetition of them; and at length many of them were voluntarily practised in succession or in combination for the common purposes of life, as in learning to walk, or to speak; and are performed with strength and velocity in proportion to the energy of the volition, that excites them, and the quantity of sensorial power. 2. Another great class of voluntary motions consists of the ideas of recollection. We will to repeat a certain train of ideas, as of the alphabet backwards; and if any ideas, that do not belong to this intended train, intrude themselves by other connections, we will to reject them, and voluntarily persist in the determined train. So at my approach to a house which I have but once visited, and that at the distance of many months, I will to recollect the names of the numerous family I expect to see there, and I do recollect them. On this voluntary recollection of ideas our faculty of reason depends, as it enables us to acquire an idea of the dissimilitude of any two ideas. Thus if you voluntarily produce the idea of a right-angled triangle, and then of a square; and after having excited these ideas repeatedly, you excite the idea of their difference, which is that of another right-angled triangle inverted over the former; you are said to reason upon this subject, or to compare your ideas. These ideas of recollection, like the muscular motions above mentioned, were originally excited by the irritation of external bodies, and were termed ideas of perception: afterwards the pleasure or pain, that accompanied these motions, induced a repetition of them in the absence of the external body, by which they were first excited; and then they were termed ideas of imagination. At length they become voluntarily practised in succession or in combination for the common purposes of life; as when we make ourselves masters of the history of mankind, or of the sciences they have investigated; and are then called ideas of recollection; and are performed with strength and velocity in proportion to the energy of the volition that excites them, and the quantity of sensorial power. II. 1. The muscular motions above described, that are most frequently obedient to the will are nevertheless occasionally causable by painful or pleasurable sensation, as in the starting from fear, and the contraction of the calf of the leg in the cramp. 2. In like manner the sensual motions, or ideas, that are most frequently connected with volition, are nevertheless occasionally causable by painful or pleasurable sensation. As the histories of men, or the description of places, which we have voluntarily taken pains to remember, sometimes occur to us in our dreams. III. 1. The muscular motions that are generally subservient to volition, are also occasionally causable by irritation, as in stretching the limbs after sleep, and yawning. In this manner a contraction of the arm is produced by passing the electric fluid from the Leyden phial along its muscles; and that even though the limb is paralytic. The sudden motion of the arm produces a disagreeable sensation in the joint, but the muscles seem to be brought into action simply by irritation. 2. The ideas, that are generally subservient to the will, are in like manner occasionally excited by irritation; as when we view again an object, we have before well studied, and often recollected. IV. 1. Innumerable trains or tribes of motions are associated with these voluntary muscular motions above mentioned; as when I will to extend my arm to a distant object, some other muscles are brought into action, and preserve the balance of my body. And when I wish to perform any steady exertion, as in threading a needle, or chopping with an ax, the pectoral muscles are at the same time brought into action to preserve the trunk of the body motionless, and we cease to respire for a time. 2. In like manner the voluntary sensual motions, or ideas of recollection, are associated with many other trains or tribes of ideas. As when I voluntarily recollect a gothic window, that I saw some time ago, the whole front of the cathedral occurs to me at the same time. * * * * * SECT. X. OF ASSOCIATE MOTIONS. I. 1. _Many muscular motions excited by irritations in trains or tribes become associated._ 2. _And many ideas._ II. 1. _Many sensitive muscular motions become associated._ 2. _And many sensitive ideas._ III. 1. _Many voluntary muscular motions become associated._ 2. _And then become obedient to sensation or irritation._ 3. _And many voluntary ideas become associated._ All the fibrous motions, whether muscular or sensual, which are frequently brought into action together, either in combined tribes, or in successive trains, become so connected by habit, that when one of them is reproduced the others have a tendency to succeed or accompany it. I. 1. Many of our muscular motions were originally excited in successive trains, as the contractions of the auricles and of the ventricles of the heart; and others in combined tribes, as the various divisions of the muscles which compose the calf of the leg, which were originally irritated into synchronous action by the tædium or irksomeness of a continued posture. By frequent repetitions these motions acquire associations, which continue during our lives, and even after the destruction of the greatest part of the sensorium; for the heart of a viper or frog will continue to pulsate long after it is taken from the body; and when it has entirely ceased to move, if any part of it is goaded with a pin, the whole heart will again renew its pulsations. This kind of connection we shall term irritative association, to distinguish it from sensitive and voluntary associations. 2. In like manner many of our ideas are originally excited in tribes; as all the objects of sight, after we become so well acquainted with the laws of vision, as to distinguish figure and distance as well as colour; or in trains, as while we pass along the objects that surround us. The tribes thus received by irritation become associated by habit, and have been termed complex ideas by the writers of metaphysics, as this book, or that orange. The trains have received no particular name, but these are alike associations of ideas, and frequently continue during our lives. So the taste of a pine-apple, though we eat it blindfold, recalls the colour and shape of it; and we can scarcely think on solidity without figure. II. 1. By the various efforts of our sensations to acquire or avoid their objects, many muscles are daily brought into successive or synchronous actions; these become associated by habit, and are then excited together with great facility, and in many instances gain indissoluble connections. So the play of puppies and kittens is a representation of their mode of fighting or of taking their prey; and the motions of the muscles necessary for those purposes become associated by habit, and gain a great adroitness of action by these early repetitions: so the motions of the abdominal muscles, which were originally brought into concurrent action, with the protrusive motion of the rectum or bladder by sensation, become so conjoined with them by habit, that they not only easily obey these sensations occasioned by the stimulus of the excrement and urine, but are brought into violent and unrestrainable action in the strangury and tenesmus. This kind of connection we shall term sensitive association. 2. So many of our ideas, that have been excited together or in succession by our sensations, gain synchronous or successive associations, that are sometimes indissoluble but with life. Hence the idea of an inhuman or dishonourable action perpetually calls up before us the idea of the wretch that was guilty of it. And hence those unconquerable antipathies are formed, which some people have to the sight of peculiar kinds of food, of which in their infancy they have eaten to excess or by constraint. III. 1. In learning any mechanic art, as music, dancing, or the use of the sword, we teach many of our muscles to act together or in succession by repeated voluntary efforts; which by habit become formed into tribes or trains of association, and serve all our purposes with great facility, and in some instances acquire an indissoluble union. These motions are gradually formed into a habit of acting together by a multitude of repetitions, whilst they are yet separately causable by the will, as is evident from the long time that is taken up by children in learning to walk and to speak; and is experienced by every one, when he first attempts to skate upon the ice or to swim: these we shall term voluntary associations. 2. All these muscular movements, when they are thus associated into tribes or trains, become afterwards not only obedient to volition, but to the sensations and irritations; and the same movement composes a part of many different tribes or trains of motion. Thus a single muscle, when it acts in consort with its neighbours on one side, assists to move the limb in one direction; and in another, when, it acts with those in its neighbourhood on the other side; and in other directions, when it acts separately or jointly with those that lie immediately under or above it; and all these with equal facility after their associations have been well established. The facility, with which each muscle changes from one associated tribe to another, and that either backwards or forwards, is well observable in the muscles of the arm in moving the windlass of an air-pump; and the slowness of those muscular movements, that have not been associated by habit, may be experienced by any one, who shall attempt to saw the air quick perpendicularly with one hand, and horizontally with the other at the same time. 3. In learning every kind of science we voluntarily associate many tribes and trains of ideas, which afterwards are ready for all the purposes either of volition, sensation, or irritation; and in some instances acquire indissoluble habits of acting together, so as to affect our reasoning, and influence our actions. Hence the necessity of a good education. These associate ideas are gradually formed into habits of acting together by frequent repetition, while they are yet separately obedient to the will; as is evident from the difficulty we experience in gaining so exact an idea of the front of St. Paul's church, as to be able to delineate it with accuracy, or in recollecting a poem of a few pages. And these ideas, thus associated into tribes, not only make up the parts of the trains of volition, sensation, and irritation; but the same idea composes a part of many different tribes and trains of ideas. So the simple idea of whiteness composes a part of the complex idea of snow, milk, ivory; and the complex idea of the letter A composes a part of the several associated trains of ideas that make up the variety of words, in which this letter enters. The numerous trains of these associated ideas are divided by Mr. Hume into three classes, which he has termed contiguity, causation, and resemblance. Nor should we wonder to find them thus connected together, since it is the business of our lives to dispose them into those three classes; and we become valuable to ourselves and our friends, as we succeed in it. Those who have combined an extensive class of ideas by the contiguity of time or place, are men learned in the history of mankind, and of the sciences they have cultivated. Those who have connected a great class of ideas of resemblances, possess the source of the ornaments of poetry and oratory, and of all rational analogy. While those who have connected great classes of ideas of causation, are furnished with the powers of producing effects. These are the men of active wisdom, who lead armies to victory, and kingdoms to prosperity; or discover and improve the sciences, which meliorate and adorn the condition of humanity. * * * * * SECT. XI. ADDITIONAL OBSERVATIONS ON THE SENSORIAL POWERS. I. _Stimulation is of various kinds adapted to the organs of sense, to the muscles, to hollow membranes, and glands. Some objects irritate our senses by repeated impulses._ II. 1. _Sensation and volition frequently affect the whole sensorium._ 2. _Emotions, passions, appetites._ 3. _Origin of desire and aversion. Criterion of voluntary actions, difference of brutes and men._ 4. _Sensibility and voluntarity._ III. _Associations formed before nativity, irritative motions mistaken for officiated ones._ _Irritation._ I. The various organs of sense require various kinds of stimulation to excite them into action; the particles of light penetrate the cornea and humours of the eye, and then irritate the naked retina; rapid particles, dissolved or diffused in water or saliva, and odorous ones, mixed or combined with the air, irritate the extremities of the nerves of taste and smell; which either penetrate, or are expanded on the membranes of the tongue and nostrils; the auditory nerves are stimulated by the vibrations of the atmosphere communicated by means of the tympanum and of the fluid, whether of air or of water, behind it; and the nerves of touch by the hardness of surrounding bodies, though the cuticle is interposed between these bodies and the medulla of the nerve. As the nerves of the senses have each their appropriated objects, which stimulate them into activity; so the muscular fibres, which are the terminations of other sets of nerves, have their peculiar objects, which excite them into action; the longitudinal muscles are stimulated into contraction by extension, whence the stretching or pandiculation after a long continued posture, during which they have been kept in a state of extension; and the hollow muscles are excited into action by distention, as those of the rectum and bladder are induced to protrude their contents from their sense of the distention rather than of the acrimony of those contents. There are other objects adapted to stimulate the nerves, which terminate in variety of membranes, and those especially which form the terminations of canals; thus the preparations of mercury particularly affect the salivary glands, ipecacuanha the stomach, aloe the sphincter of the anus, cantharides that of the bladder, and lastly every gland of the body appears to be indued with a kind of taste, by which it selects or forms each its peculiar fluid from the blood; and by which it is irritated into activity. Many of these external properties of bodies, which stimulate our organs of sense, do not seem to effect this by a single impulse, but by repeated impulses; as the nerve of the ear is probably not excitable by a single vibration of air, nor the optic nerve by a single particle of light; which circumstance produces some analogy between those two senses, at the same time the solidity of bodies is perceived by a single application of a solid body to the nerves of touch, and that even through the cuticle; and we are probably possessed of a peculiar sense to distinguish the nice degrees of heat and cold. The senses of touch and of hearing acquaint us with the mechanical impact and vibration of bodies, those of smell and taste seem to acquaint us with some of their chemical properties, while the sense of vision and of heat acquaint us with the existence of their peculiar fluids. _Sensation and Volition._ II. Many motions are produced by pleasure or pain, and that even in contradiction to the power of volition, as in laughing, or in the strangury; but as no name has been given to pleasure or pain, at the time it is exerted so as to cause fibrous motions, we have used the term sensation for this purpose; and mean it to bear the same analogy to pleasure and pain, that the word volition does to desire and aversion. 1. It was mentioned in the fifth Section, that, what we have termed sensation is a motion of the central parts, or of the whole sensorium, _beginning_ at some of the extremities of it. This appears first, because our pains and pleasures are always caused by our ideas or muscular motions, which are the motions of the extremities of the sensorium. And, secondly, because the sensation of pleasure or pain frequently continues some time after the ideas or muscular motions which excited it have ceased: for we often feel a glow of pleasure from an agreeable reverie, for many minutes after the ideas, that were the subject of it, have escaped our memory; and frequently experience a dejection of spirits without being able to assign the cause of it but by much recollection. When the sensorial faculty of desire or aversion is exerted so as to cause fibrous motions, it is termed volition; which is said in Sect. V. to be a motion of the central parts, or of the whole sensorium, _terminating_ in some of the extremities of it. This appears, first, because our desires and aversions always terminate in recollecting and comparing our ideas, or in exerting our muscles; which are the motions of the extremities of the sensorium. And, secondly, because desire or aversion begins, and frequently continues for a time in the central parts of the sensorium, before it is peculiarly exerted at the extremities of it; for we sometimes feel desire or aversion without immediately knowing their objects, and in consequence without immediately exerting any of our muscular or sensual motions to attain them: as in the beginning of the passion of love, and perhaps of hunger, or in the ennui of indolent people. Though sensation and volition begin or terminate at the extremities or central parts of the sensorium, yet the whole of it is frequently influenced by the exertion of these faculties, as appears from their effects on the external habit: for the whole skin is reddened by shame, and an universal trembling is produced by fear: and every muscle of the body is agitated in angry people by the desire of revenge. There is another very curious circumstance, which shews that sensation and volition are movements of the sensorium in contrary directions; that is, that volition begins at the central parts of it, and proceeds to the extremities; and that sensation begins at the extremities, and proceeds to the central parts: I mean that these two sensorial faculties cannot be strongly exerted at the same time; for when we exert our volition strongly, we do not attend to pleasure or pain; and conversely, when we are strongly affected with the sensation of pleasure or pain, we use no volition. As will be further explained in Section XVIII. on sleep, and Section XXXIV. on volition. 2. All our emotions and passions seem to arise out of the exertions of these two faculties of the animal sensorium. Pride, hope, joy, are the names of particular pleasures: shame, despair, sorrow, are the names of peculiar pains: and love, ambition, avarice, of particular desires: hatred, disgust, fear, anxiety, of particular aversions. Whilst the passion of anger includes the pain from a recent injury, and the aversion to the adversary that occasioned it. And compassion is the pain we experience at the sight of misery, and the desire of relieving it. There is another tribe of desires, which are commonly termed appetites, and are the immediate consequences of the absence of some irritative motions. Those, which arise from defect of internal irritations, have proper names conferred upon them, as hunger, thirst, lust, and the desire of air, when our respiration is impaired by noxious vapours; and of warmth, when we are exposed to too great a degree of cold. But those, whose stimuli are external to the body, are named from the objects, which are by nature constituted to excite them; these desires originate from our past experience of the pleasurable sensations they occasion, as the smell of an hyacinth, or the taste of a pine-apple. Whence it appears, that our pleasures and pains are at least as various and as numerous as our irritations; and that our desires and aversions must be as numerous as our pleasures and pains. And that as sensation is here used as a general term for our numerous pleasures and pains, when they produce the contractions of our fibres; so volition is the general name for our desires and aversions, when they produce fibrous contractions. Thus when a motion of the central parts, or of the whole sensorium, terminates in the exertion of our muscles, it is generally called voluntary action; when it terminates in the exertion of our ideas, it is termed recollection, reasoning, determining. 3. As the sensations of pleasure and pain are originally introduced by the irritations of external objects: so our desires and aversions are originally introduced by those sensations; for when the objects of our pleasures or pains are at a distance, and we cannot instantaneously possess the one, or avoid the other, then desire or aversion is produced, and a voluntary exertion of our ideas or muscles succeeds. The pain of hunger excites you to look out for food, the tree, that shades you, presents its odoriferous fruit before your eyes, you approach, pluck, and eat. The various movements of walking to the tree, gathering the fruit, and masticating it, are associated motions introduced by their connection with sensation; but if from the uncommon height of the tree, the fruit be inaccessible, and you are prevented from quickly possessing the intended pleasure, desire is produced. The consequence of this desire is, first, a deliberation about the means to gain the object of pleasure in process of time, as it cannot be procured immediately; and, secondly, the muscular action necessary for this purpose. You voluntarily call up all your ideas of causation, that are related to the effect you desire, and voluntarily examine and compare them, and at length determine whether to ascend the tree, or to gather stones from the neighbouring brook, is easier to practise, or more promising of success; and, finally, you gather the stones, and repeatedly fling them to dislodge the fruit. Hence then we gain a criterion to distinguish voluntary acts or thoughts from those caused by sensation. As the former are always employed about the _means_ to acquire pleasurable objects, or the _means_ to avoid painful ones; while the latter are employed in the possession of those, which are already in our power. Hence the activity of this power of volition produces the great difference between the human and the brute creation. The ideas and the actions of brutes are almost perpetually employed about their present pleasures, or their present pains; and, except in the few instances which are mentioned in Section XVI, on instinct, they seldom busy themselves about the means of procuring future bliss, or of avoiding future misery; so that the acquiring of languages, the making of tools, and labouring for money, which are all only the means to procure pleasures; and the praying to the Deity, as another means to procure happiness, are characteristic of human nature. 4. As there are many diseases produced by the quantity of the sensation of pain or pleasure being too great or too little; so are there diseases produced by the susceptibility of the constitution to motions causable by these sensations being too dull or too vivid. This susceptibility of the system to sensitive motions is termed sensibility, to distinguish it from sensation, which is the actual existence or exertion of pain or pleasure. Other classes of diseases are owing to the excessive promptitude, or sluggishness of the constitution to voluntary exertions, as well as to the quantity of desire or of aversion. This susceptibility of the system to voluntary motions is termed voluntarity, to distinguish it from volition, which is the exertion of desire or aversion; these diseases will be treated of at length in the progress of the work. _Association._ III. 1. It is not easy to assign a cause, why those animal movements, that have once occurred in succession, or in combination, should afterwards have a tendency to succeed or accompany each other. It is a property of animation, and distinguishes this order of being from the other productions of nature. When a child first wrote the word man, it was distinguished in his mind into three letters, and those letters into many parts of letters; but by repeated use the word man becomes to his hand in writing it, as to his organs of speech in pronouncing it, but one movement without any deliberation, or sensation, or irritation, interposed between the parts of it. And as many separate motions of our muscles thus become united, and form, as it were, one motion; so each separate motion before such union may be conceived to consist of many parts or spaces moved through; and perhaps even the individual fibres of our muscles have thus gradually been brought to act in concert, which habits began to be acquired as early as the very formation of the moving organs, long before the nativity of the animal; as explained in the Section XVI. 2. on instinct. 2. There are many motions of the body, belonging to the irritative class, which might by a hasty observer be mistaken for associated ones; as the peristaltic motion of the stomach and intestines, and the contractions of the heart and arteries, might be supposed to be associated with the irritative motions of their nerves of sense, rather than to be excited by the irritation of their muscular fibres by the distention, acrimony, or momentum of the blood. So the distention or elongation of muscles by objects external to them irritates them into contraction, though the cuticle or other parts may intervene between the stimulating body and the contracting muscle. Thus a horse voids his excrement when its weight or bulk irritates the rectum or sphincter ani. These muscles act from the irritation of distention, when he excludes his excrement, but the muscles of the abdomen and diaphragm are brought into motion by association with those of the sphincter and rectum. * * * * * SECT. XII. OF STIMULUS, SENSORIAL EXERTION, AND FIBROUS CONTRACTION. I. Of fibrous contraction. 1. _Two particles of a fibre cannot approach without the intervention of something, as in magnetism, electricity, elasticity. Spirit of life is not electric ether. Galvani's experiments._ 2. _Contraction of a fibre._ 3. _Relaxation succeeds._ 4. _Successive contractions, with intervals. Quick pulse from debility, from paucity of blood. Weak contractions performed in less time, and with shorter intervals._ 5. _Last situation of the fibres continues after contraction._ 6. _Contraction greater than usual induces pleasure or pain._ 7. _Mobility of the fibres uniform. Quantity of sensorial power fluctuates. Constitutes excitability._ II. Of sensorial exertion. 1. _Animal motion includes stimulus, sensorial power, and contractile fibres. The sensorial faculties act separately or conjointly. Stimulus of four kinds. Strength and weakness defined. Sensorial power perpetually exhausted and renewed. Weakness from defect of stimulus. From defect of sensorial power, the direct and indirect debility of Dr. Brown. Why we become warm in Buxton bath after a time, and see well after a time in a darkish room. Fibres may act violently, or with their whole force, and yet feebly. Great exertion in inflammation explained. Great muscular force of some insane people._ 2. _Occasional accumulation of sensorial power in muscles subject to constant stimulus. In animals sleeping in winter. In eggs, seeds, schirrous tumours, tendons, bones._ 3. _Great exertion introduces pleasure or pain. Inflammation. Libration of the system between torpor and activity. Fever-fits._ 4. _Desire and aversion introduced. Excess of volition cures fevers._ III. Of repeated stimulus. 1. _A stimulus repeated too frequently looses effect. As opium, wine, grief. Hence old age. Opium and aloes in small doses._ 2. _A stimulus not repeated too frequently does not lose effect. Perpetual movement of the vital organs._ 3. _A stimulus repeated at uniform times produces greater effect. Irritation combined with association._ 4. _A stimulus repeated frequently and uniformly may be withdrawn, and the action of the organ will continue. Hence the bark cures agues, and strengthens weak constitutions._ 5. _Defect of stimulus repeated at certain intervals causes fever-fits._ 6. _Stimulus long applied ceases to act a second time._ 7. _If a stimulus excites sensation in an organ not usually excited into sensation, inflammation is produced._ IV. Of stimulus greater than natural. 1. _A stimulus greater than natural diminishes the quantity of sensorial power in general._ 2. _In particular organs._ 3. _Induces the organ into spasmodic actions._ 4. _Induces the antagonist fibres into action._ 5. _Induces the organ into convulsive or fixed spasms._ 6. _Produces paralysis of the organ._ V. Of stimulus less than natural. 1. _Stimulus less than natural occasions accumulation of sensorial power in general._ 2. _In particular organs, flushing of the face in a frosty morning. In fibres subject to perpetual stimulus only. Quantity of sensorial power inversely as the stimulus._ 3. _Induces pain. As of cold, hunger, head-ach._ 4. _Induces more feeble and frequent contraction. As in low fevers. Which are frequently owing to deficiency of sensorial power rather than to deficiency of stimulus._ 5. _Inverts successive trains of motion. Inverts ideas._ 6. _Induces paralysis and death._ VI. Cure of increased exertion. 1. _Natural cure of exhaustion of sensorial power._ 2. _Decrease the irritations. Venesection. Cold. Abstinence._ 3. _Prevent the previous cold fit. Opium. Bark. Warmth. Anger. Surprise._ 4. _Excite some other part of the system. Opium and warm bath relieve pains both from defect and from excess of stimulus._ 5. _First increase the stimulus above, and then decrease it beneath the natural quantity._ VII. Cure of decreased exertion. 1. _Natural cure by accumulation of sensorial power. Ague-fits. Syncope._ 2. _Increase the stimulation, by wine, opium, given so as not to intoxicate. Cheerful ideas._ 3. _Change the kinds of stimulus._ 4. _Stimulate the associated organs. Blisters of use in heart-burn, and cold extremities._ 5. _Decrease the stimulation for a time, cold bath._ 6. _Decrease the stimulation below natural, and then increase it above natural. Bark after emetics. Opium after venesection. Practice of Sydenham in chlorosis._ 7. _Prevent unnecessary expenditure of sensorial power. Decumbent posture, silence, darkness. Pulse quickened by rising out of bed._ 8. _To the greatest degree of quiescence apply the least stimulus. Otherwise paralysis or inflammation of the organ ensues. Gin, wine, blisters, destroy by too great stimulation in fevers with debility. Intoxication in the slightest degree succeeded by debility. Golden rule for determining the best degree of stimulus in low fevers. Another golden rule for determining the quantity of spirit which those, who are debilitated by drinking it, may safely omit._ I. _Of fibrous contraction._ 1. If two particles of iron lie near each other without motion, and afterwards approach each other; it is reasonable to conclude that something besides the iron particles is the cause of their approximation; this invisible something is termed magnetism. In the same manner, if the particles, which compose an animal muscle, do not touch each other in the relaxed state of the muscle, and are brought into contact during the contraction of the muscle, it is reasonable to conclude, that some other agent is the cause of this new approximation. For nothing can act, where it does not exist; for to act includes to exist; and therefore the particles of the muscular fibre (which in its state of relaxation are supposed not to touch) cannot affect each other without the influence of some intermediate agent; this agent is here termed the spirit of animation, or sensorial power, but may with equal propriety be termed the power, which causes contraction; or may be called by any other name, which the reader may choose to affix to it. The contraction of a muscular fibre may be compared to the following electric experiment, which is here mentioned not as a philosophical analogy, but as an illustration or simile to facilitate the conception of a difficult subject. Let twenty very small Leyden phials properly coated be hung in a row by fine silk threads at a small distance from each other; let the internal charge of one phial be positive, and of the other negative alternately, if a communication be made from the internal surface of the first to the external surface of the last in the row, they will all of them instantly approach each other, and thus shorten a line that might connect them like a muscular fibre. See Botanic Garden, p. 1. Canto I. 1. 202, note on Gymnotus. The attractions of electricity or of magnetism do not apply philosophically to the illustration of the contraction of animal fibres, since the force of those attractions increases in some proportion inversely as the distance, but in muscular motion there appears no difference in velocity or strength during the beginning or end of the contraction, but what may be clearly ascribed to the varying mechanic advantage in the approximation of one bone to another. Nor can muscular motion be assimilated with greater plausibility to the attraction of cohesion or elasticity; for in bending a steel spring, as a small sword, a less force is required to bend it the first inch than the second; and the second than the third; the particles of steel on the convex side of the bent spring endeavouring to restore themselves more powerfully the further they are drawn from each other. See Botanic Garden, P. I. addit. Note XVIII. I am aware that this may be explained another way, by supposing the elasticity of the spring to depend more on the compression of the particles on the concave side than on the extension of them on the convex side; and by supposing the elasticity of the elastic gum to depend more on the resistance to the lateral compression of its particles than to the longitudinal extension of them. Nevertheless in muscular contraction, as above observed, there appears no difference in the velocity or force of it at its commencement or at its termination; from whence we must conclude that animal contraction is governed by laws of its own, and not by those of mechanics, chemistry, magnetism, or electricity. On these accounts I do not think the experiments conclusive, which were lately published by Galvani, Volta, and others, to shew a similitude between the spirit of animation, which contracts the muscular fibres, and the electric fluid. Since the electric fluid may act only as a more potent stimulus exciting the muscular fibres into action, and not by supplying them with a new quantity of the spirit of life. Thus in a recent hemiplegia I have frequently observed, when the patient yawned and stretched himself, that the paralytic limbs moved also, though they were totally disobedient to the will. And when he was electrified by passing shocks from the affected hand to the affected foot, a motion of the paralytic limbs was also produced. Now as in the act of yawning the muscles of the paralytic limbs were excited into action by the stimulus of the irksomeness of a continued posture, and not by any additional quantity of the spirit of life; so we may conclude, that the passage of the electric fluid, which produced a similar effect, acted only as a stimulus, and not by supplying any addition of sensorial power. If nevertheless this theory should ever become established, a stimulus must be called an eductor of vital ether; which stimulus may consist of sensation or volition, as in the electric eel, as well as in the appulses of external bodies; and by drawing off the charges of vital fluid may occasion the contraction or motions of the muscular fibres, and organs of sense. 2. The immediate effect of the action of the spirit of animation or sensorial power on the fibrous parts of the body, whether it acts in the mode of irritation, sensation, volition, or association, is a contraction of the animal fibre, according to the second law of animal causation. Sect. IV. Thus the stimulus of the blood induces the contraction of the heart; the agreeable taste of a strawberry produces the contraction of the muscles of deglutition; the effort of the will contracts the muscles, which move the limbs in walking; and by association other muscles of the trunk are brought into contraction to preserve the balance of the body. The fibrous extremities of the organs of sense have been shewn, by the ocular spectra in Sect. III. to suffer similar contraction by each of the above modes of excitation; and by their configurations to constitute our ideas. 3. After animal fibres have for some time been excited into contraction, a relaxation succeeds, even though the exciting cause continues to act. In respect to the irritative motions this is exemplified in the peristaltic contractions of the bowels; which cease and are renewed alternately, though the stimulus of the aliment continues to be uniformly applied; in the sensitive motions, as in strangury, tenesmus, and parturition, the alternate contractions and relaxations of the muscles exist, though the stimulus is perpetual. In our voluntary exertions it is experienced, as no one can hang long by the hands, however vehemently he wills so to do; and in the associate motions the constant change of our attitudes evinces the necessity of relaxation to those muscles, which have been long in action. This relaxation of a muscle after its contraction, even though the stimulus continues to be applied, appears to arise from the expenditure or diminution of the spirit of animation previously resident in the muscle, according to the second law of animal causation in Sect. IV. In those constitutions, which are termed weak, the spirit of animation becomes sooner exhausted, and tremulous motions are produced, as in the hands of infirm people, when they lift a cup to their mouths. This quicker exhaustion of the spirit of animation is probably owing to a less quantity of it residing in the acting fibres, which therefore more frequently require a supply from the nerves, which belong to them. 4. If the sensorial power continues to act, whether it acts in the mode of irritation, sensation, volition, or association, a new contraction of the animal fibre succeeds after a certain interval; which interval is of shorter continuance in weak people than in strong ones. This is exemplified in the shaking of the hands of weak people, when they attempt to write. In a manuscript epistle of one of my correspondents, which is written in a small hand, I observed from four to six zigzags in the perpendicular stroke of every letter, which shews that both the contractions of the fingers, and intervals between them, must have been performed in very short periods of time. The times of contraction of the muscles of enfeebled people being less, and the intervals between those contractions being less also, accounts for the quick pulse in fevers with debility, and in dying animals. The shortness of the intervals between one contraction and another in weak constitutions, is probably owing to the general deficiency of the quantity of the spirit of animation, and that therefore there is a less quantity of it to be received at each interval of the activity of the fibres. Hence in repeated motions, as of the fingers in performing on the harpsichord, it would at first sight appear, that swiftness and strength were incompatible; nevertheless the single contraction of a muscle is performed with greater velocity as well as with greater force by vigorous constitutions, as in throwing a javelin. There is however another circumstance, which may often contribute to cause the quickness of the pulse in nervous fevers, as in animals bleeding to death in the slaughter-house; which is the deficient quantity of blood; whence the heart is but half distended, and in consequence sooner contracts. See Sect. XXXII. 2. 1. For we must not confound frequency of repetition with quickness of motion, or the number of pulsations with the velocity, with which the fibres, which constitute the coats of the arteries, contract themselves. For where the frequency of the pulsations is but seventy-five in a minute, as in health; the contracting fibres, which constitute the sides of the arteries, may move through a greater space in a given time, than where the frequency of pulsation is one hundred and fifty in a minute, as in some fevers with great debility. For if in those fevers the arteries do not expand themselves in their diastole to more than half the usual diameter of their diastole in health, the fibres which constitute their coats, will move through a less space in a minute than in health, though they make two pulsations for one. Suppose the diameter of the artery during its systole to be one line, and that the diameter of the same artery during its diastole is in health is four lines, and in a fever with, great debility only two lines. It follows, that the arterial fibres contract in health from a circle of twelve lines in circumference to a circle of three lines in circumference, that is they move through a space of nine lines in length. While the arterial fibres in the fever with debility would twice contract from a circle of six lines to a circle of three lines; that is while they move through a space equal to six lines. Hence though the frequency of pulsation in fever be greater as two to one, yet the velocity of contraction in health is greater as nine to six, or as three to two. On the contrary in inflammatory diseases with strength, as in the pleurisy, the velocity of the contracting sides of the arteries is much greater than in health, for if we suppose the number of pulsations in a pleurisy to be half as much more than in health, that is as one hundred and twenty to eighty, (which is about what generally happens in inflammatory diseases) and if the diameter of the artery in diastole be one third greater than in health, which I believe is near the truth, the result will be, that the velocity of the contractile sides of the arteries will be in a pleurisy as two and a half to one, compared to the velocity of their contraction in a state of health, for if the circumference of the systole of the artery be three lines, and the diastole in health be twelve lines in circumference, and in a pleurisy eighteen lines; and secondly, if the artery pulsates thrice in the diseased state for twice in the healthy one, it follows, that the velocity of contraction in the diseased state to that in the healthy state will be forty-five to eighteen, or as two and a half to one. From hence it would appear, that if we had a criterion to determine the velocity of the arterial contractions, it would at the same time give us their strength, and thus be of more service in distinguishing diseases, than the knowledge of their frequency. As such a criterion cannot be had, the frequency of pulsation, the age of the patient being allowed for, will in some measure assist us to distinguish arterial strength from arterial debility, since in inflammatory diseases with strength the frequency seldom exceeds one hundred and eighteen or one hundred and twenty pulsations in a minute; unless under peculiar circumstance, as the great additional stimuli of wine or of external heat. 5. After a muscle or organ of sense has been excited into contraction, and the sensorial power ceases to act, the last situation or configuration of it continues; unless it be disturbed by the action of some antagonist fibres, or other extraneous power. Thus in weak or languid people, wherever they throw their limbs on their bed or sofa, there they lie, till another exertion changes their attitude; hence one kind of ocular spectra seems to be produced after looking at bright objects; thus when a fire-stick is whirled round in the night, there appears in the eye a complete circle of fire; the action or configuration of one part of the retina not ceasing before the return of the whirling fire. Thus if any one looks at the setting sun for a short time, and then covers his closed eyes with his hand, he will for many seconds of time perceive the image of the sun on his retina. A similar image of all other bodies would remain some time in the eye, but is effaced by the eternal change of the motions of the extremity of this nerve in our attention to other objects. See Sect. XVIII. 5. on Sleep. Hence the dark spots, and other ocular spectra, are more frequently attended to, and remain longer in the eyes of weak people, as after violent exercise, intoxication, or want of sleep. 6. A contraction of the fibres somewhat greater than usual introduces pleasurable sensation into the system, according to the fourth law of animal causation. Hence the pleasure in the beginning of drunkenness is owing to the increased action of the system from the stimulus of vinous spirit or of opium. If the contractions be still greater in energy or duration, painful sensations are introduced, as in consequence of great heat, or caustic applications, or fatigue. If any part of the system, which is used to perpetual activity, as the stomach, or heart, or the fine vessels of the skin, acts for a time with less energy, another kind of painful sensation ensues, which is called hunger, or faintness, or cold. This occurs in a less degree in the locomotive muscles, and is called wearysomeness. In the two former kinds of sensation there is an expenditure of sensorial power, in these latter there is an accumulation of it. 7. We have used the words exertion of sensorial power as a general term to express either irritation, sensation, volition, or association; that is, to express the activity or motion of the spirit of animation, at the time it produces the contractions of the fibrous parts of the system. It may be supposed that there may exist a greater or less mobility of the fibrous parts of our system, or a propensity to be stimulated into contraction by the greater or less quantity or energy of the spirit of animation; and that hence if the exertion of the sensorial power be in its natural state, and the mobility of the fibres be increased, the same quantity of fibrous contraction will be caused, as if the mobility of the fibres continues in its natural state, and the sensorial exertion be increased. Thus it may be conceived, that in diseases accompanied with strength, as in inflammatory fevers with arterial strength, that the cause of greater fibrous contraction, may exist in the increased mobility of the fibres, whose contractions are thence both more forceable and more frequent. And that in diseases attended with debility, as in nervous fevers, where the fibrous contractions are weaker, and more frequent, it may be conceived that the cause consists in a decrease of mobility of the fibres; and that those weak constitutions, which are attended with cold extremities and large pupils of the eyes, may possess less mobility of the contractile fibres, as well as less quantity of exertion of the spirit of animation. In answer to this mode of reasoning it may be sufficient to observe, that the contractile fibres consist of inert matter, and when the sensorial power is withdrawn, as in death, they possess no power of motion at all, but remain in their last state, whether of contraction or relaxation, and must thence derive the whole of this property from the spirit of animation. At the same time it is not improbable, that the moving fibres of strong people may possess a capability of receiving or containing a greater quantity of the spirit of animation than those of weak people. In every contraction of a fibre there is an expenditure of the sensorial power, or spirit of animation; and where the exertion of this sensorial power has been for some time increased, and the muscles or organs of sense have in consequence acted with greater energy, its propensity to activity is proportionally lessened; which is to be ascribed to the exhaustion or diminution of its quantity. On the contrary, where there has been less fibrous contraction than usual for a certain time, the sensorial power or spirit of animation becomes accumulated in the inactive part of the system. Hence vigour succeeds rest, and hence the propensity to action of all our organs of sense and muscles is in a state of perpetual fluctuation. The irritability for instance of the retina, that is, its quantity of sensorial power, varies every moment according to the brightness or obscurity of the object last beheld compared with the present one. The same occurs to our sense of heat, and to every part of our system, which is capable of being excited into action. When this variation of the exertion of the sensorial power becomes much and permanently above or beneath the natural quantity, it becomes a disease. If the irritative motions be too great or too little, it shews that the stimulus of external things affect this sensorial power too violently or too inertly. If the sensitive motions be too great or too little, the cause arises from the deficient or exuberant quantity of sensation produced in consequence of the motions of the muscular fibres or organs of sense; if the voluntary actions are diseased the cause is to be looked for in the quantity of volition produced in consequence of the desire or aversion occasioned by the painful or pleasurable sensations above mentioned. And the diseases of associations probably depend on the greater or less quantity of the other three sensorial powers by which they were formed. From whence it appears that the propensity to action, whether it be called irritability, sensibility, voluntarity, or associability, is only another mode of expression for the quantity of sensorial power residing in the organ to be excited. And that on the contrary the words inirritability and insensibility, together with inaptitude to voluntary and associate motions, are synonymous with deficiency of the quantity of sensorial power, or of the spirit of animation, residing in the organs to be excited. II. _Of sensorial Exertion._ 1. There are three circumstances to be attended to in the production of animal motions, 1st. The stimulus. 2d. The sensorial power. 3d. The contractile fibre. 1st. A stimulus, external to the organ, originally induces into action the sensorial faculty termed irritation; this produces the contraction of the fibres, which, if it be perceived at all, introduces pleasure or pain; which in their active state are termed sensation; which is another sensorial faculty, and occasionally produces contraction of the fibres; this pleasure or pain is therefore to be considered as another stimulus, which may either act alone or in conjunction with the former faculty of the sensorium termed irritation. This new stimulus of pleasure or pain either induces into action the sensorial faculty termed sensation, which then produces the contraction of the fibres; or it introduces desire or aversion, which excite into action another sensorial faculty, termed volition, and may therefore be considered as another stimulus, which either alone or in conjunction with one or both of the two former faculties of the sensorium produces the contraction of animal fibres. There is another sensorial power, that of association, which perpetually, in conjunction with one or more of the above, and frequently singly, produces the contraction of animal fibres, and which is itself excited into action by the previous motions of contracting fibres. Now as the sensorial power, termed irritation, residing in any particular fibres, is excited into exertion by the stimulus of external bodies acting on those fibres; the sensorial power, termed sensation, residing in any particular fibres is excited into exertion by the stimulus of pleasure or pain acting on those fibres; the sensorial power, termed volition, residing in any particular fibres is excited into exertion by the stimulus of desire or aversion; and the sensorial power, termed association, residing in any particular fibres, is excited into action by the stimulus of other fibrous motions, which had frequently preceded them. The word stimulus may therefore be used without impropriety of language, for any of these four causes, which excite the four sensorial powers into exertion. For though the immediate cause of volition has generally been termed _a motive_; and that of irritation only has generally obtained the name of _stimulus_; yet as the immediate cause, which excites the sensorial powers of sensation, or of association into exertion, have obtained no general name, we shall use the word stimulus for them all. Hence the quantity of motion produced in any particular part of the animal system will be as the quantity of stimulus and the quantity of sensorial power, or spirit of animation, residing in the contracting fibres. Where both these quantities are great, _strength_ is produced, when that word is applied to the motions of animal bodies. Where either of them is deficient, _weakness_ is produced, as applied to the motions of animal bodies. Now as the sensorial power, or spirit of animation, is perpetually exhausted by the expenditure of it in fibrous contractions, and is perpetually renewed by the secretion or production of it in the brain and spinal marrow, the quantity of animal strength must be in a perpetual state of fluctuation on this account; and if to this be added the unceasing variation of all the four kinds of stimulus above described, which produce the exertions of the sensorial powers, the ceaseless vicissitude of animal strength becomes easily comprehended. If the quantity of sensorial power remains the same, and the quantity of stimulus be lessened, a weakness of the fibrous contractions ensues, which may be denominated _debility from defect of stimulus_. If the quantity of stimulus remains the same, and the quantity of sensorial power be lessened, another kind of weakness ensues, which may be termed _debility from defect of sensorial power_; the former of these is called by Dr. Brown, in his Elements of Medicine, direct debility, and the latter indirect debility. The coincidence of some parts of this work with correspondent deductions in the Brunonian Elementa Medicina, a work (with some exceptions) of great genius, must be considered as confirmations of the truth of the theory, as they were probably arrived at by different trains of reasoning. Thus in those who have been exposed to cold and hunger there is a deficiency of stimulus. While in nervous fever there is a deficiency of sensorial power. And in habitual drunkards, in a morning before their usual potation, there is a deficiency both of stimulus and of sensorial power. While, on the other hand, in the beginning of intoxication there is an excess of stimulus; in the hot-ach, after the hands have been immersed in snow, there is a redundancy of sensorial power; and in inflammatory diseases with arterial strength, there is an excess of both. Hence if the sensorial power be lessened, while the quantity of stimulus remains the same as in nervous fever, the frequency of repetition of the arterial contractions may continue, but their force in respect to removing obstacles, as in promoting the circulation of the blood, or the velocity of each contraction, will be diminished, that is, the animal strength will be lessened. And secondly, if the quantity of sensorial power be lessened, and the stimulus be increased to a certain degree, as in giving opium in nervous fevers, the arterial contractions may be performed more frequently than natural, yet with less strength. And thirdly, if the sensorial power continues the same in respect to quantity, and the stimulus be somewhat diminished, as in going into a darkish room, or into a coldish bath, suppose of about eighty degrees of heat, as Buxton-bath, a temporary weakness of the affected fibres is induced, till an accumulation of sensorial power gradually succeeds, and counterbalances the deficiency of stimulus, and then the bath ceases to feel cold, and the room ceases to appear dark; because the fibres of the subcutaneous vessels, or of the organs of sense, act with their usual energy. A set of muscular fibres may thus be stimulated into violent exertion, that is, they may act frequently, and with their whole sensorial power, but may nevertheless not act strongly; because the quantity of their sensorial power was originally small, or was previously exhausted. Hence a stimulus may be great, and the irritation in consequence act with its full force, as in the hot paroxysms of nervous fever; but if the sensorial power, termed irritation, be small in quantity, the force of the fibrous contractions, and the times of their continuance in their contracted state, will be proportionally small. In the same manner in the hot paroxysm of putrid fevers, which are shewn in Sect. XXXIII. to be inflammatory fevers with arterial debility, the sensorial power termed sensation is exerted with great activity, yet the fibrous contractions, which produce the circulation of the blood, are performed without strength, because the quantity of sensorial power then residing in that part of the system is small. Thus in irritative fever with arterial strength, that is, with excess of spirit of animation, the quantity of exertion during the hot part of the paroxysm is to be estimated from the quantity of stimulus, and the quantity of sensorial power. While in sensitive (or inflammatory) fever with arterial strength, that is, with excess of spirit of animation, the violent and forcible actions of the vascular system during the hot part of the paroxysm are induced by the exertions of two sensorial powers, which are excited by two kinds of stimulus. These are the sensorial power of irritation excited by the stimulus of bodies external to the moving fibres, and the sensorial power of sensation excited by the pain in consequence of the increased contractions of those moving fibres. And in insane people in some cases the force of their muscular actions will be in proportion to the quantity of sensorial power, which they possess, and the quantity of the stimulus of desire or aversion, which excites their volition into action. At the same time in other cases the stimulus of pain or pleasure, and the stimulus of external bodies, may excite into action the sensorial powers of sensation and irritation, and thus add greater force to their muscular actions. 2. The application of the stimulus, whether that stimulus be some quality of external bodies, or pleasure or pain, or desire or aversion, or a link of association, excites the correspondent sensorial power into action, and this causes the contraction of the fibre. On the contraction of the fibre a part of the spirit of animation becomes expended, and the fibre ceases to contract, though the stimulus continues to be applied; till in a certain time the fibre having received a supply of sensorial power is ready to contract again, if the stimulus continues to be applied. If the stimulus on the contrary be withdrawn, the same quantity of quiescent sensorial power becomes resident in the fibre as before its contraction; as appears from the readiness for action of the large locomotive muscles of the body in a short time after common exertion. But in those muscular fibres, which are subject to constant stimulus, as the arteries, glands, and capillary vessels, another phenomenon occurs, if their accustomed stimulus be withdrawn; which is, that the sensorial power becomes accumulated in the contractile fibres, owing to the want of its being perpetually expended, or carried away, by their usual unremitted contractions. And on this account those muscular fibres become afterwards excitable into their natural actions by a much weaker stimulus; or into unnatural violence of action by their accustomed stimulus, as is seen in the hot fits of intermittent fevers, which are in consequence of the previous cold ones. Thus the minute vessels of the skin are constantly stimulated by the fluid matter of heat; if the quantity of this stimulus of heat be a while diminished, as in covering the hands with snow, the vessels cease to act, as appears from the paleness of the skin; if this cold application of snow be continued but a short time, the sensorial power, which had habitually been supplied to the fibres, becomes now accumulated in them, owing to the want of its being expended by their accustomed contractions. And thence a less stimulus of heat will now excite them into violent contractions. If the quiescence of fibres, which had previously been subject to perpetual stimulus, continues a longer time; or their accustomed stimulus be more completely withdrawn; the accumulation of sensorial power becomes still greater, as in those exposed to cold and hunger; pain is produced, and the organ gradually dies from the chemical changes, which take place in it; or it is at a great distance of time restored to action by stimulus applied with great caution in small quantity, as happens to some larger animals and to many insects, which during the winter months lie benumbed with cold, and are said to sleep, and to persons apparently drowned, or apparently frozen to death. Snails have been said to revive by throwing them into water after having been many years shut up in the cabinets of the curious; and eggs and seeds in general are restored to life after many months of torpor by the stimulus of warmth and moisture. The inflammation of schirrous tumours, which have long existed in a state of inaction, is a process of this kind; as well as the sensibility acquired by inflamed tendons and bones, which had at their formation a similar sensibility, which had so long lain dormant in their uninflamed state. 3. If after long quiescence from defect of stimulus the fibres, which had previously been habituated to perpetual stimulus, are again exposed to but their usual quantity of it; as in those who have suffered the extremes of cold or hunger; a violent exertion of the affected organ commences, owing, as above explained, to the great accumulation of sensorial power. This violent exertion not only diminishes the accumulated spirit of animation, but at the same time induces pleasure or pain into the system, which, whether it be succeeded by inflammation or not, becomes an additional stimulus, and acting along with the former one, produces still greater exertions; and thus reduces the sensorial power in the contracting fibres beneath its natural quantity. When the spirit of animation is thus exhausted by useless exertions, the organ becomes torpid or unexcitable into action, and a second fit of quiescence succeeds that of abundant activity. During this second fit of quiescence the sensorial power becomes again accumulated, and another fit of exertion follows in train. These vicissitudes of exertion and inertion of the arterial system constitute the paroxysms of remittent fevers; or intermittent ones, when there is an interval of the natural action of the arteries between the exacerbations. In these paroxysms of fevers, which consist of the libration of the arterial system between the extremes of exertion and quiescence, either the fits become less and less violent from the contractile fibres becoming coming less excitable to the stimulus by habit, that is, by becoming accustomed to it, as explained below XII. 3. 1. or the whole sensorial power becomes exhausted, and the arteries cease to beat, and the patient dies in the cold part of the paroxysm. Or secondly, so much pain is introduced into the system by the violent contractions of the fibres, that inflammation arises, which prevents future cold fits by expending a part of the sensorial power in the extension of old vessels or the production of new ones; and thus preventing the too great accumulation or exertion of it in other parts of the system; or which by the great increase of stimulus excites into great action the whole glandular system as well as the arterial, and thence a greater quantity of sensorial power is produced in the brain, and thus its exhaustion in any peculiar part of the system ceases to be affected. 4. Or thirdly, in consequence of the painful or pleasurable sensation above mentioned, desire and aversion are introduced, and inordinate volition succeeds; which by its own exertions expends so much of the spirit of animation, that the two other sensorial faculties, or irritation and sensation, act so much more feebly; that the paroxysms of fever, or that libration between the extremes of exertion and inactivity of the arterial system, gradually subsides. On this account a temporary insanity is a favourable sign in fevers, as I have had some opportunities of observing. III. _Of repeated Stimulus._ 1. When a stimulus is repeated more frequently than the expenditure of sensorial power can be renewed in the acting organ, the effect of the stimulus becomes gradually diminished. Thus if two grains of opium be swallowed by a person unused to so strong a stimulus, all the vascular systems in the body act with greater energy, all the secretions and the absorption from those secreted fluids are increased in quantity; and pleasure or pain are introduced into the system, which adds an additional stimulus to that already too great. After some hours the sensorial power becomes diminished in quantity, expended by the great activity of the system; and thence, when the stimulus of the opium is withdrawn, the fibres will not obey their usual degree of natural stimulus, and a consequent torpor or quiescence succeeds, as is experienced by drunkards, who on the day after a great excess of spirituous potation feel indigestion, head-ach, and general debility. In this fit of torpor or quiescence of a part or of the whole of the system, an accumulation of the sensorial power in the affected fibres is formed, and occasions a second paroxysm of exertion by the application only of the natural stimulus, and thus a libration of the sensorial exertion between one excess and the other continues for two or three days, where the stimulus was violent in degree; and for weeks in some fevers, from the stimulus of contagious matter. But if a second dose of opium be exhibited before the fibres have regained their natural quantity of sensorial power, its effect will be much less than the former, because the spirit of animation or sensorial power is in part exhausted by the previous excess of exertion. Hence all medicines repeated too frequently gradually lose their effect, as opium and wine. Many things of disagreeable taste at first cease to be disagreeable by frequent repetition, as tobacco; grief and pain gradually diminish, and at length cease altogether, and hence life itself becomes tolerable. Besides the temporary diminution of the spirit of animation or sensorial power, which is naturally stationary or resident in every living fibre, by a single exhibition of a powerful stimulus, the contractile fibres themselves, by the perpetual application of a new quantity of stimulus, before they have regained their natural quantity of sensorial power, appear to suffer in their capability of receiving so much as the natural quantity of sensorial power; and hence a permanent deficiency of spirit of animation takes place, however long the stimulus may have been withdrawn. On this cause depends the permanent debility of those, who have been addicted to intoxication, the general weakness of old age, and the natural debility or inirritability of those, who have pale skins and large pupils of their eyes. There is a curious phenomenon belongs to this place, which has always appeared difficult of solution; and that is, that opium or aloes may be exhibited in small doses at first, and gradually increased to very large ones without producing stupor or diarrhoea. In this case, though the opium and aloes are given in such small doses as not to produce intoxication or catharsis, yet they are exhibited in quantities sufficient in some degree to exhaust the sensorial power, and hence a stronger and a stronger dose is required; otherwise the medicine would soon cease to act at all. On the contrary, if the opium or aloes be exhibited in a large dose at first, so as to produce intoxication or diarrhoea; after a few repetitions the quantity of either of them may be diminished, and they will still produce this effect. For the more powerful stimulus dissevers the progressive catenations of animal motions, described in Sect. XVII. and introduces a new link between them; whence every repetition strengthens this new association or catenation, and the stimulus may be gradually decreased, or be nearly withdrawn, and yet the effect shall continue; because the sensorial power of association or catenation being united with the stimulus, increases in energy with every repetition of the catenated circle; and it is by these means that all the irritative associations of motions are originally produced. 2. When a stimulus is repeated at such distant intervals of time, that the natural quantity of sensorial power becomes completely restored in the acting fibres, it will act with the same energy as when first applied. Hence those who have lately accustomed themselves to large doses of opium by beginning with small ones, and gradually increasing them, and repeating them frequently, as mentioned in the preceding paragraph; if they intermit the use of it for a few days only, must begin again with as small doses as they took at first, otherwise they will experience the inconveniences of intoxication. On this circumstance depend the constant unfailing effects of the various kinds of stimulus, which excite into action all the vascular systems in the body; the arterial, venous, absorbent, and glandular vessels, are brought into perpetual unwearied action by the fluids, which are adapted to stimulate them; but these have the sensorial power of association added to that of irritation, and even in some degree that of sensation, and even of volition, as will be spoken of in their places; and life itself is thus carried on by the production of sensorial power being equal to its waste or expenditure in the perpetual movement of the vascular organization. 3. When a stimulus is repeated at uniform intervals of time with such distances between them, that the expenditure of sensorial power in the acting fibres becomes completely renewed, the effect is produced with greater facility or energy. For the sensorial power of association is combined with the sensorial power of irritation, or, in common language, the acquired habit assists the power of the stimulus. This circumstance not only obtains in the annual and diurnal catenations of animal motions explained in Sect. XXXVI. but in every less circle of actions or ideas, as in the burthen of a song, or the iterations of a dance; and constitutes the pleasure we receive from repetition and imitation; as treated of in Sect. XXII. 2. 4. When a stimulus has been many times repeated at uniform intervals, so as to produce the complete action of the organ, it may then be gradually diminished, or totally withdrawn, and the action of the organ will continue. For the sensorial power of association becomes united with that of irritation, and by frequent repetition becomes at length of sufficient energy to carry on the new link in the circle of actions, without the irritation which at first introduced it. Hence, when the bark is given at stated intervals for the cure of intermittent fevers, if sixty grains of it be given every three hours for the twenty-four hours preceding the expected paroxysm, so as to stimulate the defective part of the system into action, and by that means to prevent the torpor or quiescence of the fibres, which constitutes the cold fit; much less than half the quantity, given before the time at which another paroxysm of quiescence would have taken place, will be sufficient to prevent it; because now the sensorial power, termed association, acts in a twofold manner. First, in respect to the period of the catenation in which the cold fit was produced, which is now dissevered by the stronger stimulus of the first doses of the bark; and, secondly, because each dose of bark being repeated at periodical times, has its effect increased by the sensorial faculty of association being combined with that of irritation. Now, when sixty grains of Peruvian bark are taken twice a day, suppose at ten o'clock and at six, for a fortnight, the irritation excited by this additional stimulus becomes a part of the diurnal circle of actions, and will at length carry on the increased action of the system without the assistance of the stimulus of the bark. On this theory the bitter medicines, chalybeates, and opiates in appropriated doses, exhibited for a fortnight, give permanent strength to pale feeble children, and other weak constitutions. 5. When a defect of stimulus, as of heat, recurs at certain diurnal intervals, which induces some torpor or quiescence of a part of the system, the diurnal catenation of actions becomes disordered, and a new association with this link of torpid action is formed; on the next period the quantity of quiescence will be increased, suppose the same defect of stimulus to recur, because now the new association conspires with the defective irritation in introducing the torpid action of this part of the diurnal catenation. In this manner many fever-fits commence, where the patient is for some days indisposed at certain hours, before the cold paroxysm of fever is completely formed. See Sect. XVII. 3. 3. on Catenation of Animal Motions. 6. If a stimulus, which at first excited the affected organ into so great exertion as to produce sensation, be continued for a certain time, it will cease to produce sensation both then and when repeated, though the irritative motions in consequence of it may continue or be re-excited. Many catenations of irritative motions were at first succeeded by sensation, as the apparent motions of objects when we walk past them, and probably the vital motions themselves in the early state of our existence. But as those sensations were followed by no movements of the system in consequence of them, they gradually ceased to be produced, not being joined to any succeeding link of catenation. Hence contagious matter, which has for some weeks stimulated the system into great and permanent sensation, ceases afterwards to produce general sensation, or inflammation, though it may still induce topical irritations. See Sect. XXXIII. 2. 8. XIX. 9. Our absorbent system then seems to receive those contagious matters, which it has before experienced, in the same manner as it imbibes common moisture or other fluids; that is, without being thrown into so violent action as to produce sensation; the consequence of which is an increase of daily energy or activity, till inflammation and its consequences succeed. 7. If a stimulus excites an organ into such violent contractions as to produce sensation, the motions of which organ had not usually produced sensation, this new sensorial power, added to the irritation occasioned by the stimulus, increases the activity of the organ. And if this activity be catenated with the diurnal circle of actions, an increasing inflammation is produced; as in the evening paroxysms of small-pox, and other fevers with inflammation. And hence schirrous tumours, tendons and membranes, and probably the arteries themselves become inflamed, when they are strongly stimulated. IV. _Of Stimulus greater than natural._ 1. A quantity of stimulus greater than natural, producing an increased exertion of sensorial power, whether that exertion be in the mode of irritation, sensation, volition, or association, diminishes the general quantity of it. This fact is observable in the progress of intoxication, as the increased quantity or energy of the irritative motions, owing to the stimulus of vinous spirit, introduces much pleasurable sensation into the system, and much exertion of muscular or sensual motions in consequence of this increased sensation; the voluntary motions, and even the associate ones, become much impaired or diminished; and delirium and staggering succeed. See Sect. XXI. on Drunkenness. And hence the great prostration of the strength of the locomotive muscles in some fevers, is owing to the exhaustion of sensorial power by the increased action of the arterial system. In like manner a stimulus greater than natural, applied to a part of the system, increases the exertion of sensorial power in that part, and diminishes it in some other part. As in the commencement of scarlet fever, it is usual to see great redness and heat on the faces and breasts of children, while at the same time their feet are colder than natural; partial heats are observable in other fevers with debility, and are generally attended with torpor or quiescence of some other part of the system. But these partial exertions of sensorial power are sometimes attended with increased partial exertions in other parts of the system, which sympathize with them, as the flushing of the face after a full meal. Both these therefore are to be ascribed to sympathetic associations, explained in Sect. XXXV. and not to general exhaustion or accumulation of sensorial power. 2. A quantity of stimulus greater than natural, producing an increased exertion of sensorial power in any particular organ, diminishes the quantity of it in that organ. This appears from the contractions of animal fibres being not so easily excited by a less stimulus after the organ has been subjected to a greater. Thus after looking at any luminous object of a small size, as at the setting sun, for a short time, so as not much to fatigue the eye, this part of the retina becomes less sensible to smaller quantities of light; hence when the eyes are turned on other less luminous parts of the sky, a dark spot is seen resembling the shape of the sun, or other luminous object which we last behold. See Sect. XL. No. 2. Thus we are some time before we can distinguish objects in an obscure room after coming from bright day-light, though the iris presently contracts itself. We are not able to hear weak sounds after loud ones. And the stomachs of those who have been much habituated to the stronger stimulus of fermented or spirituous liquors, are not excited into due action by weaker ones. 3. A quantity of stimulus something greater than the last mentioned, or longer continued, induces the organ into spasmodic action, which ceases and recurs alternately. Thus on looking for a time on the setting sun, so as not greatly to fatigue the sight, a yellow spectrum is seen when the eyes are closed and covered, which continues for a time, and then disappears and recurs repeatedly before it entirely vanishes. See Sect. XL. No. 5. Thus the action of vomiting ceases and is renewed by intervals, although the emetic drug is thrown up with the first effort. A tenesmus continues by intervals some time after the exclusion of acrid excrement; and the pulsations of the heart of a viper are said to continue some time after it is cleared from its blood. In these cases the violent contractions of the fibres produce pain according to law 4; and this pain constitutes an additional kind or quantity of excitement, which again induces the fibres into contraction, and which painful excitement is again renewed, and again induces contractions of the fibres with gradually diminishing effect. 4. A quantity of stimulus greater than that last mentioned, or longer continued, induces the antagonist muscles into spasmodic action. This is beautifully illustrated by the ocular spectra described in Sect. XL. No. 6. to which the reader is referred. From those experiments there is reason to conclude that the fatigued part of the retina throws itself into a contrary mode of action like oscitation or pandiculation, as soon as the stimulus, which has fatigued it, is withdrawn; but that it still remains liable to be excited into action by any other colours except the colour with which it has been fatigued. Thus the yawning and stretching the limbs after a continued action or attitude seems occasioned by the antagonist muscles being stimulated by their extension during the contractions of those in action, or in the situation in which that action last left them. 5. A quantity of stimulus greater than the last, or longer continued, induces variety of convulsions or fixed spasms either of the affected organ or of the moving fibres in the other parts of the body. In respect to the spectra in the eye, this is well illustrated in No. 7 and 8, of Sect. XL. Epileptic convulsions, as the emprosthotonos and opisthotonos, with the cramp of the calf of the leg, locked jaw, and other cataleptic fits, appear to originate from pain, as some of these patients scream aloud before the convulsion takes place; which seems at first to be an effort to relieve painful sensation, and afterwards an effort to prevent it. In these cases the violent contractions of the fibres produce so much pain, as to constitute a perpetual excitement; and that in so great a degree as to allow but small intervals of relaxation of the contracting fibres as in convulsions, or no intervals at all as in fixed spasms. 6. A quantity of stimulus greater than the last, or longer continued, produces a paralysis of the organ. In many cases this paralysis is only a temporary effect, as on looking long on a small area of bright red silk placed on a sheet of white paper on the floor in a strong light, the red silk gradually becomes paler, and at length disappears; which evinces that a part of the retina, by being violently excited, becomes for a time unaffected by the stimulus of that colour. Thus cathartic medicines, opiates, poisons, contagious matter, cease to influence our system after it has been habituated to the use of them, except by the exhibition of increased quantities of them; our fibres not only become unaffected by stimuli, by which they have previously been violently irritated, as by the matter of the small-pox or measles; but they also become unaffected by sensation, where the violent exertions, which disabled them, were in consequence of too great quantity of sensation. And lastly the fibres, which become disobedient to volition, are probably disabled by their too violent exertions in consequence of too great a quantity of volition. After every exertion of our fibres a temporary paralysis succeeds, whence the intervals of all muscular contractions, as mentioned in No. 3 and 4 of this Section; the immediate cause of these more permanent kinds of paralysis is probably owing in the same manner to the too great exhaustion of the spirit of animation in the affected part; so that a stronger stimulus is required, or one of a different kind from that, which occasioned those too violent contractions, to again excite the affected organ into activity; and if a stronger stimulus could be applied, it must again induce paralysis. For these powerful stimuli excite pain at the same time, that they produce irritation; and this pain not only excites fibrous motions by its stimulus, but it also produces volition; and thus all these stimuli acting at the same time, and sometimes with the addition of their associations, produce so great exertion as to expend the whole of the sensorial power in the affected fibres. V. _Of Stimulus less than natural._ 1. A quantity of stimulus less than natural, producing a decreased exertion of sensorial power, occasions an accumulation of the general quantity of it. This circumstance is observable in the hemiplagia, in which the patients are perpetually moving the muscles, which are unaffected. On this account we awake with greater vigour after sleep, because during so many hours, the great usual expenditure of sensorial power in the performance of voluntary actions, and in the exertions of our organs of sense, in consequence of the irritations occasioned by external objects had been suspended, and a consequent accumulation had taken place. In like manner the exertion of the sensorial power less than natural in one part of the system, is liable to produce an increase of the exertion of it in some other part. Thus by the action of vomiting, in which the natural exertion of the motions of the stomach are destroyed or diminished, an increased absorption of the pulmonary and cellular lymphatics is produced, as is known by the increased absorption of the fluid deposited in them in dropsical cases. But these partial quiescences of sensorial power are also sometimes attended with other partial quiescences, which sympathize with them, as cold and pale extremities from hunger. These therefore are to be ascribed to the associations of sympathy explained in Sect. XXXV. and not to the general accumulation of sensorial power. 2. A quantity of stimulus less than natural, applied to fibres previously accustomed to perpetual stimulus, is succeeded by accumulation of sensorial power in the affected organ. The truth of this proposition is evinced, because a stimulus less than natural, if it be somewhat greater than that above mentioned, will excite the organ so circumstanced into violent activity. Thus on a frosty day with wind, the face of a person exposed to the wind is at first pale and shrunk; but on turning the face from the wind, it becomes soon of a glow with warmth and flushing. The glow of the skin in emerging from the cold-bath is owing to the same cause. It does not appear, that an accumulation of sensorial power above the natural quantity is acquired by those muscles, which are not subject to perpetual stimulus, as the locomotive muscles: these, after the greatest fatigue, only acquire by rest their usual aptitude to motion; whereas the vascular system, as the heart and arteries, after a short quiescence, are thrown into violent action by their natural quantity of stimulus. Nevertheless by this accumulation of sensorial power during the application of decreased stimulus, and by the exhaustion of it during the action of increased stimulus, it is wisely provided, that the actions of the vascular muscles and organs of sense are not much deranged by small variations of stimulus; as the quantity of sensorial power becomes in some measure inversely as the quantity of stimulus. 3. A quantity of stimulus less than that mentioned above, and continued for some time, induces pain in the affected organ, as the pain of cold in the hands, when they are immersed in snow, is owing to a deficiency of the stimulation of heat. Hunger is a pain from the deficiency of the stimulation of food. Pain in the back at the commencement of ague-fits, and the head-achs which attend feeble people, are pains from defect of stimulus, and are hence relieved by opium, essential oils, spirit of wine. As the pains, which originate from defect of stimulus, only occur in those parts of the system, which have been previously subjected to perpetual stimulus; and as an accumulation of sensorial power is produced in the quiescent organ along with the pain, as in cold or hunger, there is reason to believe, that the pain is owing to the accumulation of sensorial power. For, in the locomotive muscles, in the retina of the eye, and other organs of senses, no pain occurs from the absence of stimulus, nor any great accumulation of sensorial power beyond their natural quantity, since these organs have not been used to a perpetual supply of it. There is indeed a greater accumulation occurs in the organ of vision after its quiescence, because it is subject to more constant stimulus. 4. A certain quantity of stimulus less than natural induces the moving organ into feebler and more frequent contractions, as mentioned in No. I. 4. of this Section. For each contraction moving through a less space, or with less force, that is, with less expenditure of the spirit of animation, is sooner relaxed, and the spirit of animation derived at each interval into the acting fibres being less, these intervals likewise become shorter. Hence the tremours of the hands of people accustomed to vinous spirit, till they take their usual stimulus; hence the quick pulse in fevers attended with debility, which is greater than in fevers attended with strength; in the latter the pulse seldom beats above 120 times in a minute, in the former it frequently exceeds 140. It must be observed, that in this and the two following articles the decreased action of the system is probably more frequently occasioned by deficiency in the quantity of sensorial power, than in the quantity of stimulus. Thus those feeble constitutions which have large pupils of their eyes, and all who labour under nervous fevers, seem to owe their want of natural quantity of activity in the system to the deficiency of sensorial power; since, as far as can be seen, they frequently possess the natural quantity of stimulus. 5. A certain quantity of stimulus, less than that above mentioned, inverts the order of successive fibrous contractions; as in vomiting the vermicular motions of the stomach and duodenum are inverted, and their contents ejected, which is probably owing to the exhaustion of the spirit of animation in the acting muscles by a previous excessive stimulus, as by the root of ipecacuanha, and the consequent defect of sensorial power. The same retrograde motions affect the whole intestinal canal in ileus; and the oesophagus in globus hystericus. See this further explained in Sect. XXIX. No. 11. on Retrograde Motions. I must observe, also, that something similar happens in the production of our ideas, or sensual motions, when they are too weakly excited; when any one is thinking intensely about one thing, and carelessly conversing about another, he is liable to use the word of a contrary meaning to that which he designed, as cold weather for hot weather, summer for winter. 6. A certain quantity of stimulus, less than that above mentioned, is succeeded by paralysis, first of the voluntary and sensitive motions, and afterwards of those of irritation, and of association, which constitutes death. VI. _Cure of increased Exertion._ 1. The cure, which nature has provided for the increased exertion of any part of the system, consists in the consequent expenditure of the sensorial power. But as a greater torpor follows this exhaustion of sensorial power, as explained in the next paragraph, and a greater exertion succeeds this torpor, the constitution frequently sinks under these increasing librations between exertion and quiescence; till at length complete quiescence, that is, death, closes the scene. For, during the great exertion of the system in the hot fit of fever, an increase of stimulus is produced from the greater momentum of the blood, the greater distention of the heart and arteries, and the increased production of heat, by the violent actions of the system occasioned by this augmentation of stimulus, the sensorial power becomes diminished in a few hours much beneath its natural quantity, the vessels at length cease to obey even these great degrees of stimulus, as shewn in Sect. XL. 9. 1. and a torpor of the whole or of a part of the system ensues. Now as this second cold fit commences with a greater deficiency of sensorial power, it is also attended with a greater deficiency of stimulus than in the preceding cold fit, that is, with less momentum of blood, less distention of the heart. On this account the second cold fit becomes more violent and of longer duration than the first; and as a greater accumulation of sensorial power must be produced before the system of vessels will again obey the diminished stimulus, it follows, that the second hot fit of fever will be more violent than the former one. And that unless some other causes counteract either the violent exertions in the hot fit, or the great torpor in the cold fit, life will at length be extinguished by the expenditure of the whole of the sensorial power. And from hence it appears, that the true means of curing fevers must be such as decrease the action of the system in the hot fit, and increase it in the cold fit; that is, such as prevent the too great diminution of sensorial power in the hot fit, and the too great accumulation of it in the cold one. 2. Where the exertion of the sensorial powers is much increased, as in the hot fits of fever or inflammation, the following are the usual means of relieving it. Decrease the irritations by blood-letting, and other evacuations; by cold water taken into the stomach, or injected as an enema, or used externally; by cold air breathed into the lungs, and diffused over the skin; with food of less stimulus than the patient has been accustomed to. 3. As a cold fit, or paroxysm of inactivity of some parts of the system, generally precedes the hot fit, or paroxysm of exertion, by which the sensorial power becomes accumulated, this cold paroxysm should be prevented by stimulant medicines and diet, as wine, opium, bark, warmth, cheerfulness, anger, surprise. 4. Excite into greater action some other part of the system, by which means the spirit of animation may be in part expended, and thence the inordinate actions of the diseased part may be lessened. Hence when a part of the skin acts violently, as of the face in the eruption of the small-pox, if the feet be cold they should be covered. Hence the use of a blister applied near a topical inflammation. Hence opium and warm bath relieve pains both from excess and defect of stimulus. 5. First increase the general stimulation above its natural quantity, which may in some degree exhaust the spirit of animation, and then decrease the stimulation beneath its natural quantity. Hence after sudorific medicines and warm air, the application of refrigerants may have greater effect, if they could be administered without danger of producing too great torpor of some part of the system; as frequently happens to people in health from coming out of a warm room into the cold air, by which a topical inflammation in consequence of torpor of the mucous membrane of the nostril is produced, and is termed a cold in the head. VII. _Cure of decreased Exertion._ 1. Where the exertion of the sensorial powers is much decreased, as in the cold fits of fever, a gradual accumulation of the spirit of animation takes place; as occurs in all cases where inactivity or torpor of a part of the system exists; this accumulation of sensorial power increases, till stimuli less than natural are sufficient to throw it into action, then the cold fit ceases; and from the action of the natural stimuli a hot one succeeds with increased activity of the whole system. So in fainting fits, or syncope, there is a temporary deficiency of sensorial exertion, and a consequent quiescence of a great part of the system. This quiescence continues, till the sensorial power becomes again accumulated in the torpid organs; and then the usual diurnal stimuli excite the revivescent parts again into action; but as this kind of quiescence continues but a short time compared to the cold paroxysm of an ague, and less affects the circulatory system, a less superabundancy of exertion succeeds in the organs previously torpid, and a less excess of arterial activity. See Sect. XXXIV. 1. 6. 2. In the diseases occasioned by a defect of sensorial exertion, as in cold fits of ague, hysteric complaint, and nervous fever, the following means are those commonly used. 1. Increase the stimulation above its natural quantity for some weeks, till a new habit of more energetic contraction of the fibres is established. This is to be done by wine, opium, bark, steel, given at exact periods, and in appropriate quantities; for if these medicines be given in such quantity, as to induce the least degree of intoxication, a debility succeeds from the useless exhaustion of spirit of animation in consequence of too great exertion of the muscles or organs of sense. To these irritative stimuli should be added the sensitive ones of cheerful ideas, hope, affection. 3. Change the kinds of stimulus. The habits acquired by the constitution depend on such nice circumstances, that when one kind of stimulus ceases to excite the sensorial power into the quantity of exertion necessary to health, it is often sufficient to change the stimulus for another apparently similar in quantity and quality. Thus when wine ceases to stimulate the constitution, opium in appropriate doses supplies the defect; and the contrary. This is also observed in the effects of cathartic medicines, when one loses its power, another, apparently less efficacious, will succeed. Hence a change of diet, drink, and stimulating medicines, is often advantageous in diseases of debility. 4. Stimulate the organs, whose motions are associated with the torpid parts of the system. The actions of the minute vessels of the various parts of the external skin are not only associated with each other, but are strongly associated with those of some of the internal membranes, and particularly of the stomach. Hence when the exertion of the stomach is less than natural, and indigestion and heartburn succeed, nothing so certainly removes these symptoms as the stimulus of a blister on the back. The coldness of the extremities, as of the nose, ears, or fingers, are hence the best indication for the successful application of blisters. 5. Decrease the stimulus for a time. By lessening the quantity of heat for a minute or two by going into the cold bath, a great accumulation of sensorial power is produced; for not only the minute vessels of the whole external skin for a time become inactive, as appears by their paleness; but the minute vessels of the lungs lose much of their activity also by concert with those of the skin, as appears from the difficulty of breathing at first going into cold water. On emerging from the bath the sensorial power is thrown into great exertion by the stimulus of the common degree of the warmth of the atmosphere, and a great production of animal heat is the consequence. The longer a person continues in the cold bath the greater must be the present inertion of a great part of the system, and in consequence a greater accumulation of sensorial power. Whence M. Pomè recommends some melancholy patients to be kept from two to six hours in spring-water, and in baths still colder. 6. Decrease the stimulus for a time below the natural, and then increase it above natural. The effect of this process, improperly used, is seen in giving much food, or applying much warmth, to those who have been previously exposed to great hunger, or to great cold. The accumulated sensorial power is thrown into so violent exertion, that inflammations and mortifications supervene, and death closes the catastrophe. In many diseases this method is the most successful; hence the bark in agues produces more certain effect after the previous exhibition of emetics. In diseases attended with violent pain, opium has double the effect, if venesection and a cathartic have been previously used. On this seems to have been founded the successful practice of Sydenham, who used venesection and a cathartic in chlorosis before the exhibition of the bark, steel, and opiates. 7. Prevent any unnecessary expenditure of sensorial power. Hence in fevers with debility, a decumbent posture is preferred, with silence, little light, and such a quantity of heat as may prevent any chill sensation, or any coldness of the extremities. The pulse of patients in fevers with debility increases in frequency above ten pulsations in a minute on their rising out of bed. For the expenditure of sensorial power to preserve an erect posture of the body adds to the general deficiency of it, and thus affects the circulation. 8. The longer in time and the greater in degree the quiescence or inertion of an organ has been, so that it still retains life or excitability, the less stimulus should at first be applied to it. The quantity of stimulation is a matter of great nicety to determine, where the torpor or quiescence of the fibres has been experienced in a great degree, or for a considerable time, as in cold fits of the ague, in continued fevers with great debility, or in people famished at sea, or perishing with cold. In the two last cases, very minute quantities of food should be first supplied, and very few additional degrees of heat. In the two former cases, but little stimulus of wine or medicine, above what they had been lately accustomed to, should be exhibited, and this at frequent and stated intervals, so that the effect of one quantity may be observed before the exhibition of another. If these circumstances are not attended to, as the sensorial power becomes accumulated in the quiescent fibres, an inordinate exertion takes place by the increase of stimulus acting on the accumulated quantity of sensorial power, and either the paralysis, or death of the contractile fibres ensues, from the total expenditure of the sensorial power in the affected organ, owing to this increase of exertion, like the debility after intoxication. Or, secondly, the violent exertions above mentioned produce painful sensation, which becomes a new stimulus, and by thus producing inflammation, and increasing the activity of the fibres already too great, sooner exhausts the whole of the sensorial power in the acting organ, and mortification, that is, the death of the part, supervenes. Hence there have been many instances of people, whose limbs have been long benumbed by exposure to cold, who have lost them by mortification on their being too hastily brought to the fire; and of others, who were nearly famished at sea, who have died soon after having taken not more than an usual meal of food. I have heard of two well-attested instances of patients in the cold fit of ague, who have died from the exhibition of gin and vinegar, by the inflammation which ensued. And in many fevers attended with debility, the unlimited use of wine, and the wanton application of blisters, I believe, has destroyed numbers by the debility consequent to too great stimulation, that is, by the exhaustion of the sensorial power by its inordinate exertion. Wherever the least degree of intoxication exists, a proportional debility is the consequence; but there is a golden rule by which the necessary and useful quantity of stimulus in fevers with debility may be ascertained. When wine or beer are exhibited either alone or diluted with water, if the pulse becomes slower the stimulus is of a proper quantity; and should be repeated every two or three hours, or when the pulse again becomes quicker. In the chronical debility brought on by drinking spirituous or fermented liquors, there is another golden rule by which I have successfully directed the quantity of spirit which they may safely lessen, for there is no other means by which they can recover their health. It should be premised, that where the power of digestion in these patients is totally destroyed, there is not much reason to expect a return to healthful vigour. I have directed several of these patients to omit one fourth part of the quantity of vinous spirit they have been lately accustomed to, and if in a fortnight their appetite increases, they are advised to omit another fourth part; but if they perceive that their digestion becomes impaired from the want of this quantity of spirituous potation, they are advised to continue as they are, and rather bear the ills they have, than risk the encounter of greater. At the same time flesh-meat with or without spice is recommended, with Peruvian bark and steel in small quantities between their meals, and half a grain of opium or a grain, with five or eight grains of rhubarb at night. * * * * * SECT. XIII. OF VEGETABLE ANIMATION. I. 1. _Vegetables are irritable; mimosa, dionæa muscipula. Vegetable secretions._ 2. _Vegetable buds are inferior animals, are liable to greater or less irritability._ II. _Stamens and pistils of plants shew marks of sensibility._ III. _Vegetables possess some degree of volition._ IV. _Motions of plants are associated like those of animals._ V. 1. _Vegetable structure like that of animals, their anthers and stigmas are living creatures. Male-flowers of Vallisneria._ 2. _Whether vegetables, possess ideas? They have organs of sense as of touch and smell, and ideas of external things?_ I. 1. The fibres of the vegetable world, as well as those of the animal, are excitable into a variety of motion by irritations of external objects. This appears particularly in the mimosa or sensitive plant, whose leaves contract on the slightest injury; the dionæa muscipula, which was lately brought over from the marshes of America, presents us with another curious instance of vegetable irritability; its leaves are armed with spines on their upper edge, and are spread on the ground around the stem; when an insect creeps on any of them in its passage to the flower or seed, the leaf shuts up like a steel rat-trap, and destroys its enemy. See Botanic Garden, Part II. note on Silene. The various secretions of vegetables, as of odour, fruit, gum, resin, wax, honey, seem brought about in the same manner as in the glands of animals; the tasteless moisture of the earth is converted by the hop-plant into a bitter juice; as by the caterpillar in the nut-shell the sweet kernel is converted into a bitter powder. While the power of absorption in the roots and barks of vegetables is excited into action by the fluids applied to their mouths like the lacteals and lymphatics of animals. 2. The individuals of the vegetable world may be considered as inferior or less perfect animals; a tree is a congeries of many living buds, and in this respect resembles the branches of coralline, which are a congeries of a multitude of animals. Each of these buds of a tree has its proper leaves or petals for lungs, produces its viviparous or its oviparous offspring in buds or seeds; has its own roots, which extending down the stem of the tree are interwoven with the roots of the other buds, and form the bark, which is the only living part of the stem, is annually renewed, and is superinduced upon the former bark, which then dies, and with its stagnated juices gradually hardening into wood forms the concentric circles, which we see in blocks of timber. The following circumstances evince the individuality of the buds of trees. First, there are many trees, whose whole internal wood is perished, and yet the branches are vegete and healthy. Secondly, the fibres of the barks of trees are chiefly longitudinal, resembling roots, as is beautifully seen in those prepared barks, that were lately brought from Otaheita. Thirdly, in horizontal wounds of the bark of trees, the fibres of the upper lip are always elongated downwards like roots, but those of the lower lip do not approach to meet them. Fourthly, if you wrap wet moss round any joint of a vine, or cover it with moist earth, roots will shoot out from it. Fifthly, by the inoculation or engrafting of trees many fruits are produced from one stem. Sixthly, a new tree is produced from a branch plucked from an old one, and set in the ground. Whence it appears that the buds of deciduous trees are so many annual plants, that the bark is a contexture of the roots of each individual bud; and that the internal wood is of no other use but to support them in the air, and that thus they resemble the animal world in their individuality. The irritability of plants, like that of animals, appears liable to be increased or decreased by habit; for those trees or shrubs, which are brought from a colder climate to a warmer, put out their leaves and blossoms a fortnight sooner than the indigenous ones. Professor Kalm, in his Travels in New York, observes that the apple-trees brought from England blossom a fortnight sooner than the native ones. In our country the shrubs, that are brought a degree or two from the north, are observed to flourish better than those, which come from the south. The Siberian barley and cabbage are said to grow larger in this climate than the similar more southern vegetables. And our hoards of roots, as of potatoes and onions, germinate with less heat in spring, after they have been accustomed to the winter's cold, than in autumn after the summer's heat. II. The stamens and pistils of flowers shew evident marks of sensibility, not only from many of the stamens and some pistils approaching towards each other at the season of impregnation, but from many of them closing their petals and calyxes during the cold parts of the day. For this cannot be ascribed to irritation, because cold means a defect of the stimulus of heat; but as the want of accustomed stimuli produces pain, as in coldness, hunger, and thirst of animals, these motions of vegetables in closing up their flowers must be ascribed to the disgreeable sensation, and not to the irritation of cold. Others close up their leaves during darkness, which, like the former, cannot be owing to irritation, as the irritating material is withdrawn. The approach of the anthers in many flowers to the stigmas, and of the pistils of some flowers to the anthers, must be ascribed to the passion of love, and hence belongs to sensation, not to irritation. III. That the vegetable world possesses some degree of voluntary powers, appears from their necessity to sleep, which we have shewn in Sect. XVIII. to consist in the temporary abolition of voluntary power. This voluntary power seems to be exerted in the circular movement of the tendrils of vines, and other climbing vegetables; or in the efforts to turn the upper surface of their leaves, or their flowers to the light. IV. The associations of fibrous motions are observable in the vegetable world, as well as in the animal. The divisions of the leaves of the sensitive plant have been accustomed to contract at the same time from the absence of light; hence if by any other circumstance, as a slight stroke or injury, one division is irritated into contraction, the neighbouring ones contract also, from their motions being associated with those of the irritated part. So the various stamina of the class of syngenesia have been accustomed to contract together in the evening, and thence if you stimulate one of them with a pin, according to the experiment of M. Colvolo, they all contract from their acquired associations. To evince that the collapsing of the sensitive plant is not owing to any mechanical vibrations propagated along the whole branch, when a single leaf is struck with the finger, a leaf of it was slit with sharp scissors, and some seconds of time passed before the plant seemed sensible of the injury; and then the whole branch collapsed as far as the principal stem: this experiment was repeated several times with the least possible impulse to the plant. V. 1. For the numerous circumstances in which vegetable buds are analogous to animals, the reader is referred to the additional notes at the end of the Botanic Garden, Part I. It is there shewn, that the roots of vegetables resemble the lacteal system of animals; the sap-vessels in the early spring, before their leaves expand, are analogous to the placental vessels of the foetus; that the leaves of land-plants resemble lungs, and those of aquatic plants the gills of fish; that there are other systems of vessels resembling the vena portarum of quadrupeds, or the aorta of fish; that the digestive power of vegetables is similar to that of animals converting the fluids, which they absorb, into sugar; that their seeds resemble the eggs of animals, and their buds and bulbs their viviparous offspring. And, lastly, that the anthers and stigmas are real animals, attached indeed to their parent tree like polypi or coral insects, but capable of spontaneous motion; that they are affected with the passion of love, and furnished with powers of reproducing their species, and are fed with honey like the moths and butterflies, which plunder their nectaries. See Botanic Garden, Part I. add. note XXXIX. The male flowers of vallisneria approach still nearer to apparent animality, as they detach themselves from the parent plant, and float on the surface of the water to the female ones. Botanic Garden, Part II. Art. Vallisneria. Other flowers of the classes of monecia and diecia, and polygamia, discharge the fecundating farina, which floating in the air is carried to the stigma of the female flowers, and that at considerable distances. Can this be effected by any specific attraction? or, like the diffusion of the odorous particles of flowers, is it left to the currents of winds, and the accidental miscarriages of it counteracted by the quantity of its production? 2. This leads us to a curious enquiry, whether vegetables have ideas of external things? As all our ideas are originally received by our senses, the question may be changed to, whether vegetables possess any organs of sense? Certain it is, that they possess a sense of heat and cold, another of moisture and dryness, and another of light and darkness; for they close their petals occasionally from the presence of cold, moisture, or darkness. And it has been already shewn, that these actions cannot be performed simply from irritation, because cold and darkness are negative quantities, and on that account sensation or volition are implied, and in consequence a sensorium or union of their nerves. So when we go into the light, we contract the iris; not from any stimulus of the light on the fine muscles of the iris, but from its motions being associated with the sensation of too much light on the retina: which could not take place without a sensorium or center of union of the nerves of the iris with those of vision. See Botanic Garden, Part I. Canto 3. l. 440. note. Besides these organs of sense, which distinguish cold, moisture, and darkness, the leaves of mimosa, and of dionæa, and of drosera, and the stamens of many flowers, as of the berbery, and the numerous class of syngenesia, are sensible to mechanic impact, that is, they possess a sense of touch, as well as a common sensorium; by the medium of which their muscles are excited into action. Lastly, in many flowers the anthers, when mature, approach the stigma, in others the female organ approaches to the male. In a plant of collinsonia, a branch of which is now before me, the two yellow stamens are about three eights of an inch high, and diverge from each other, at an angle of about fifteen degrees, the purple style is half an inch high, and in some flowers is now applied to the stamen on the right hand, and in others to that of the left; and will, I suppose, change place to-morrow in those, where the anthers have not yet effused their powder. I ask, by what means are the anthers in many flowers, and stigmas in other flowers, directed to find their paramours? How do either of them know, that the other exists in their vicinity? Is this curious kind of storge produced by mechanic attraction, or by the sensation of love? The latter opinion is supported by the strongest analogy, because a reproduction of the species is the consequence; and then another organ of sense must be wanted to direct these vegetable amourettes to find each other, one probably analogous to our sense of smell, which in the animal world directs the new-born infant to its source of nourishment, and they may thus possess a faculty of perceiving as well as of producing odours. Thus, besides a kind of taste at the extremities of their roots, similar to that of the extremities of our lacteal vessels, for the purpose of selecting their proper food: and besides different kinds of irritability residing in the various glands, which separate honey, wax, resin, and other juices from their blood; vegetable life seems to possess an organ of sense to distinguish the variations of heat, another to distinguish the varying degrees of moisture, another of light, another of touch, and probably another analogous to our sense of smell. To these must be added the indubitable evidence of their passion of love, and I think we may truly conclude, that they are furnished with a common sensorium belonging to each bud and that they must occasionally repeat those perceptions either in their dreams or waking hours, and consequently possess ideas of so many of the properties of the external world, and of their own existence. * * * * * SECT. XIV. OF THE PRODUCTION OF IDEAS. I. _Of material and immaterial beings. Doctrine of St. Paul._ II. 1. _Of the sense of touch. Of solidity._ 2. _Of figure. Motion. Time. Place. Space. Number._ 3. _Of the penetrability of matter._ 4. _Spirit of animation possesses solidity, figure, visibility, &c. Of Spirits and angels._ 5. _The existence of external things._ III. _Of vision._ IV. _Of hearing._ V. _Of smell and taste._ VI. _Of the organ of sense by which we perceive heat and cold, not by the sense of touch._ VII. _Of the sense of extension, the whole of the locomotive muscles may be considered as one organ of sense._ VIII. _Of the senses of hunger, thirst, want of fresh air, suckling children, and lust._ IX. _Of many other organs of sense belonging to the glands. Of painful sensations from the excess of light, pressure, heat, itching, caustics, and electricity._ I. Philosophers have been much perplexed to understand, in what manner we become acquainted with the external world; insomuch that Dr. Berkly even doubted its existence, from having observed (as he thought) that none of our ideas resemble their correspondent objects. Mr. Hume asserts, that our belief depends on the greater distinctness or energy of our ideas from perception; and Mr. Reid has lately contended, that our belief of external objects is an innate principle necessarily joined with our perceptions. So true is the observation of the famous Malbranch, "that our senses are not given us to discover the essences of things, but to acquaint us with the means of preserving our existence," (L. I. ch. v.) a melancholy reflection to philosophers! Some philosophers have divided all created beings into material and immaterial: the former including all that part of being, which obeys the mechanic laws of action and reaction, but which can begin no motion of itself; the other is the cause of all motion, and is either termed the power of gravity, or of specific attraction, or the spirit of animation. This immaterial agent is supposed to exist in or with matter, but to be quite distinct from it, and to be equally capable of existence, after the matter, which now possesses it, is decomposed. Nor is this theory ill supported by analogy, since heat, electricity, and magnetism, can be given to or taken from a piece of iron; and must therefore exist, whether separated from the metal, or combined with it. From a parity of reasoning, the spirit of animation, would appear to be capable of existing as well separately from the body as with it. I beg to be understood, that I do not wish to dispute about words, and am ready to allow, that the powers of gravity, specific attraction, electricity, magnetism, and even the spirit of animation, may consist of matter of a finer kind; and to believe, with St. Paul and Malbranch, that the ultimate cause only of all motion is immaterial, that is God. St. Paul says, "in him we live and move, and have our being;" and, in the 15th chapter to the Corinthians, distinguishes between the psyche or living spirit, and the pneuma or reviving spirit. By the words spirit of animation or sensorial power, I mean only that animal life, which mankind possesses in common with brutes, and in some degree even with vegetables, and leave the consideration of the immortal part of us, which is the object of religion, to those who treat of revelation. II. 1. _Of the Sense of Touch._ The first idea we become acquainted with, are those of the sense of touch; for the foetus must experience some varieties of agitation, and exert some muscular action, in the womb; and may with great probability be supposed thus to gain some ideas of its own figure, of that of the uterus, and of the tenacity of the fluid, that surrounds it, (as appears from the facts mentioned in the succeeding Section upon Instinct.) Many of the organs of sense are confined to a small part of the body, as the nostrils, ear, or eye, whilst the sense of touch is diffused over the whole skin, but exists with a more exquisite degree of delicacy at the extremities of the fingers and thumbs, and in the lips. The sense of touch is thus very commodiously disposed for the purpose of encompassing smaller bodies, and for adapting itself to the inequalities of larger ones. The figure of small bodies seems to be learnt by children by their lips as much as by their fingers; on which account they put every new object to their mouths, when they are satiated with food, as well as when they are hungry. And puppies seem to learn their ideas of figure principally by the lips in their mode of play. We acquire our tangible ideas of objects either by the simple pressure of this organ of touch against a solid body, or by moving our organ of touch along the surface of it. In the former case we learn the length and breadth of the object by the quantity of our organ of touch, that is impressed by it: in the latter case we learn the length and breadth of objects by the continuance of their pressure on our moving organ of touch. It is hence, that we are very slow in acquiring our tangible ideas, and very slow in recollecting them; for if I now think of the tangible idea of a cube, that is, if I think of its figure, and of the solidity of every part of that figure, I must conceive myself as passing my fingers over it, and seem in some measure to feel the idea, as I formerly did the impression, at the ends of them, and am thus very slow in distinctly recollecting it. When a body compresses any part of our sense of touch, what happens? First, this part of our sensorium undergoes a mechanical compression, which is termed a stimulus; secondly, an idea, or contraction of a part of the organ of sense is excited; thirdly, a motion of the central parts, or of the whole sensorium, which is termed sensation, is produced; and these three constitute the perception of solidity. 2. _Of Figure, Motion, Time, Place, Space, Number._ No one will deny, that the medulla of the brain and nerves has a certain figure; which, as it is diffused through nearly the whole of the body, must have nearly the figure of that body. Now it follows, that the spirit of animation, or living principle, as it occupies this medulla, and no other part, (which is evinced by a great variety of cruel experiments on living animals,) it follows, that this spirit of animation has also the same figure as the medulla above described. I appeal to common sense! the spirit of animation acts, Where does it act? It acts wherever there is the medulla above mentioned; and that whether the limb is yet joined to a living animal, or whether it be recently detached from it; as the heart of a viper or frog will renew its contractions, when pricked with a pin, for many minutes of time after its exsection from the body.--Does it act any where else?--No; then it certainly exists in this part of space, and no where else; that is, it hath figure; namely, the figure of the nervous system, which is nearly the figure of the body. When the idea of solidity is excited, as above explained, a part of the extensive organ of touch is compressed by some external body, and this part of the sensorium so compressed exactly resembles _in figure_ the figure of the body that compressed it. Hence, when we acquire the idea of solidity, we acquire at the same time the idea of FIGURE; and this idea of figure, or motion of _a part_ of the organ of touch, exactly resembles _in its figure_ the figure of the body that occasions it; and thus exactly acquaints us with this property of the external world. Now, as the whole universe with all its parts possesses a certain form or figure, if any part of it moves, that form or figure of the whole is varied: hence, as MOTION is no other than a perpetual variation of figure, our idea of motion is also a real resemblance of the motion that produced it. It may be said in objection to this definition of motion, that an ivory globe may revolve on its axis, and that here will be a motion without change of figure. But the figure of the particle _x_ on one side of this globe is not the _same_ figure as the figure of _y_ on the other side, any more than the particles themselves are the same, though they are _similar_ figures; and hence they cannot change place with each other without disturbing or changing the figure of the whole. Our idea of TIME is from the same source, but is more abstracted, as it includes only the comparative velocities of these variations of figure; hence if it be asked, How long was this book in printing? it may be answered, Whilst the sun was passing through Aries. Our idea of PLACE includes only the figure of a group of bodies, not the figures of the bodies themselves. If it be asked where is Nottinghamshire, the answer is, it is surrounded by Derbyshire, Lincolnshire and Leicestershire; hence place is our idea of the figure of one body surrounded by the figures of other bodies. The idea of SPACE is a more abstracted idea of place excluding the group of bodies. The idea of NUMBER includes only the particular arrangements, or distributions of a group of bodies, and is therefore only a more abstracted idea of the parts of the figure of the group of bodies; thus when I say England is divided into forty counties, I only speak of certain divisions of its figure. Hence arises the certainty of the mathematical sciences, as they explain these properties of bodies, which are exactly resembled by our ideas of them, whilst we are obliged to collect almost all our other knowledge from experiment; that is, by observing the effects exerted by one body upon another. 3. _Of the Penetrability of Matter._ The impossibility of two bodies existing together in the same space cannot be deduced from our idea of solidity, or of figure. As soon as we perceive the motions of objects that surround us, and learn that we possess a power to move our own bodies, we experience, that those objects, which excite in us the idea of solidity and of figure, oppose this voluntary movement of our own organs; as whilst I endeavour to compress between my hands an ivory ball into a spheroid. And we are hence taught by experience, that our own body and those, which we touch, cannot exist in the same part of space. But this by no means demonstrates, that no two bodies can exist together in the same part of space. Galilæo in the preface to his works seems to be of opinion, that matter is not impenetrable; Mr. Michel, and Mr. Boscowich in his Theoria. Philos. Natur. have espoused this hypothesis: which has been lately published by Dr. Priestley, to whom the world is much indebted for so many important discoveries in science. (Hist. of Light and Colours, p. 391.) The uninterrupted passage of light through transparent bodies, of the electric æther through metallic and aqueous bodies, and of the magnetic effluvia through all bodies, would seem to give some probability to this opinion. Hence it appears, that beings may exist without possessing the property of solidity, as well as they can exist without possessing the properties, which excite our smell or taste, and can thence occupy space without detruding other bodies from it; but we cannot become acquainted with such beings by our sense of touch, any more than we can with odours or flavours without our senses of smell and taste. But that any being can exist without existing in space, is to my ideas utterly incomprehensible. My appeal is to common sense. _To be_ implies a when and a where; the one is comparing it with the motions of other beings, and the other with their situations. If there was but one object, as the whole creation may be considered as one object, then I cannot ask where it exists? for there are no other objects to compare its situation with. Hence if any one denies, that a being exists in space, he denies, that there are any other beings but that one; for to answer the question, "Where does it exist?" is only to mention the situation of the objects that surround it. In the same manner if it be asked--"When does a being exist?" The answer only specifies the successive motions either of itself, or of other bodies; hence to say, a body exists not in time, is to say, that there is, or was, no motion in the world. 4. _Of the Spirit of Animation._ But though there may exist beings in the universe, that have not the property of solidity; that is, which can possess any part of space, at the same time that it is occupied by other bodies; yet there may be other beings, that can assume this property of solidity, or disrobe themselves of it occasionally, as we are taught of spirits, and of angels; and it would seem, that THE SPIRIT OF ANIMATION must be endued with this property, otherwise how could it occasionally give motion to the limbs of animals?--or be itself stimulated into motion by the obtrusions of surrounding bodies, as of light, or odour? If the spirit of animation was always necessarily penetrable, it could not influence or be influenced by the solidity of common matter; they would exist together, but could not detrude each other from the part of space, where they exist; that is, they could not communicate motion to each other. _No two things can influence or affect each other, which have not some property common to both of them_; for to influence or affect another body is to give or communicate some property to it, that it had not before; but how can one body give that to another, which it does not possess itself?--The words imply, that they must agree in having the power or faculty of possessing some common property. Thus if one body removes another from the part of space, that it possesses, it must have the power of occupying that space itself: and if one body communicates heat or motion to another, it follows, that they have alike the property of possessing heat or motion. Hence the spirit of animation at the time it communicates or receives motion from solid bodies, must itself possess some property of solidity. And in consequence at the time it receives other kinds of motion from light, it must possess that property, which light possesses, to communicate that kind of motion; and for which no language has a name, unless it may be termed Visibility. And at the time it is stimulated into other kinds of animal motion by the particles of sapid and odorous bodies affecting the senses of taste and smell, it must resemble these particles of flavour, and of odour, in possessing some similar or correspondent property; and for which language has no name, unless we may use the words Saporosity and Odorosity for those common properties, which are possessed by our organs of taste and smell, and by the particles of sapid and odorous bodies; as the words Tangibility and Audibility may express the common property possessed by our organs of touch, and of hearing, and by the solid bodies, or their vibrations, which affect those organs. 5. Finally, though the figures of bodies are in truth resembled by the figure of the part of the organ of touch, which is stimulated into motion; and that organ resembles the solid body, which stimulates it, in its property of solidity; and though the sense of hearing resembles the vibrations of external bodies in its capability of being stimulated into motion by those vibrations; and though our other organs of sense resemble the bodies, that stimulate them, in their capability of being stimulated by them; and we hence become acquainted with these properties of the external world; yet as we can repeat all these motions of our organs of sense by the efforts of volition, or in consequence of the sensation of pleasure or pain, or by their association with other fibrous motions, as happens in our reveries or in sleep, there would still appear to be some difficulty in demonstrating the existence of any thing external to us. In our dreams we cannot determine this circumstance, because our power of volition is suspended, and the stimuli of external objects are excluded; but in our waking hours we can compare our ideas belonging to one sense with those belonging to another, and can thus distinguish the ideas occasioned by irritation from those excited by sensation, volition, or association. Thus if the idea of the sweetness of sugar should be excited in our dreams, the whiteness and hardness of it occur at the same time by association; and we believe a material lump of sugar present before us. But if, in our waking hours, the idea of the sweetness of sugar occurs to us, the stimuli of surrounding objects, as the edge of the table, on which we press, or green colour of the grass, on which we tread, prevent the other ideas of the hardness and whiteness of the sugar from being exerted by association. Or if they should occur, we voluntarily compare them with the irritative ideas of the table or grass above mentioned, and detect their fallacy. We can thus distinguish the ideas caused by the stimuli of external objects from those, which are introduced by association, sensation, or volition; and during our waking hours can thus acquire a knowledge of the external world. Which nevertheless we cannot do in our dreams, because we have neither perceptions of external bodies, nor the power of volition to enable us to compare them with the ideas of imagination. III. _Of Vision._ Our eyes observe a difference of colour, or of shade, in the prominences and depressions of objects, and that those shades uniformly vary, when the sense of touch observes any variation. Hence when the retina becomes stimulated by colours or shades of light in a certain form, as in a circular spot; we know by experience, that this is a sign, that a tangible body is before us; and that its figure is resembled by the miniature figure of the part of the organ of vision, that is thus stimulated. Here whilst the stimulated part of the retina resembles exactly the visible figure of the whole in miniature, the various kinds of stimuli from different colours mark the visible figures of the minuter parts; and by habit we instantly recall the tangible figures. Thus when a tree is the object of sight, a part of the retina resembling a flat branching figure is stimulated by various shades of colours; but it is by suggestion, that the gibbosity of the tree, and the moss, that fringes its trunk, appear before us. These are ideas of suggestion, which we feel or attend to, associated with the motions of the retina, or irritative ideas, which we do not attend to. So that though our visible ideas resemble in miniature the outline of the figure of coloured bodies, in other respects they serve only as a language, which by acquired associations introduce the tangible ideas of bodies. Hence it is, that this sense is so readily deceived by the art of the painter to our amusement and instruction. The reader will find much very curious knowledge on this subject in Bishop Berkley's Essay on Vision, a work of great ingenuity. The immediate object however of the sense of vision is light; this fluid, though its velocity is so great, appears to have no perceptible mechanical impulse, as was mentioned in the third Section, but seems to stimulate the retina into animal motion by its transmission through this part of the sensorium: for though the eyes of cats or other animals appear luminous in obscure places; yet it is probable, that none of the light, which falls on the retina, is reflected from it, but adheres to or enters into combination with the choroide coat behind it. The combination of the particles of light with opake bodies, and therefore with the choroide coat of the eye, is evinced from the heat, which is given out, as in other chemical combinations. For the sunbeams communicate no heat in their passage through transparent bodies, with which they do not combine, as the air continues cool even in the focus of the largest burning-glasses, which in a moment vitrifies a particle of opaque matter. IV. _Of the Organ of Hearing._ It is generally believed, that the tympanum of the ear vibrates mechanically, when exposed to audible sounds, like the strings of one musical instrument, when the same notes are struck upon another. Nor is this opinion improbable, as the muscles and cartilages of the larynx are employed in producing variety of tones by mechanical vibration: so the muscles and bones of the ear seem adapted to increase or diminish the tension of the tympanum for the purposes of similar mechanical vibrations. But it appears from dissection, that the tympanum is not the immediate organ of hearing, but that like the humours and cornea of the eye, it is only of use to prepare the object for the immediate organ. For the portio mollis of the auditory nerve is not spread upon the tympanum, but upon the vestibulum, and cochlea, and semicircular canals of the ear; while between the tympanum and the expansion of the auditory nerve the cavity is said by Dr. Cotunnus and Dr. Meckel to be filled with water; as they had frequently observed by freezing the heads of dead animals before they dissected them; and water being a more dense fluid than air is much better adapted to the propagation of vibrations. We may add, that even the external opening of the ear is not absolutely necessary for the perception of sound: for some people, who from these defects would have been completely deaf, have distinguished acute or grave sounds by the tremours of a stick held between their teeth propagated along the bones of the head, (Haller. Phys. T. V. p. 295). Hence it appears, that the immediate organ of hearing is not affected by the particles of the air themselves, but is stimulated into animal motion by the vibrations of them. And it is probable from the loose bones, which are found in the heads of some fishes, that the vibrations of water are sensible to the inhabitants of that element by a similar organ. The motions of the atmosphere, which we become acquainted with by the sense of touch, are combined with its solidity, weight, or vis intertiæ; whereas those, that are perceived by this organ, depend alone on its elasticity. But though the vibration of the air is the immediate object of the sense of hearing, yet the ideas, we receive by this sense, like those received from light, are only as a language, which by acquired associations acquaints us with those motions of tangible bodies, which depend on their elasticity; and which we had before learned by our sense of touch. V. _Of Smell and of Taste._ The objects of smell are dissolved in the fluid atmosphere, and those of taste in the saliva, or other aqueous fluid, for the better diffusing them on their respective organs, which seem to be stimulated into animal motion perhaps by the chemical affinities of these particles, which constitute the sapidity and odorosity of bodies with the nerves of sense, which perceive them. Mr. Volta has lately observed a curious circumstance relative to our sense of taste. If a bit of clean lead and a bit of clean silver be separately applied to the tongue and palate no taste is perceived; but by applying them in contact in respect to the parts out of the mouth, and nearly so in respect to the parts, which are immediately applied to the tongue and palate, a saline or acidulous taste is perceived, as of a fluid like a stream of electricity passing from one of them to the other. This new application of the sense of taste deserves further investigation, as it may acquaint us with new properties of matter. From the experiments above mentioned of Galvani, Volta, Fowler, and others, it appears, that a plate of zinc and a plate of silver have greater effect than lead and silver. If one edge of a plate of silver about the size of half a crown-piece be placed upon the tongue, and one edge of a plate of zinc about the same size beneath the tongue, and if their opposite edges are then brought into contact before the point of the tongue, a taste is perceived at the moment of their coming into contact; secondly, if one of the above plates be put between the upper lip and the gum of the fore-teeth, and the other be placed under the tongue, and their exterior edges be then brought into contact in a darkish room, a flash of light is perceived in the eyes. These effects I imagine only shew the sensibility of our nerves of sense to very small quantities of the electric fluid, as it passes through them; for I suppose these sensations are occasioned by slight electric shocks produced in the following manner. By the experiments published by Mr. Bennet, with his ingenious doubler of electricity, which is the greatest discovery made in that science since the coated jar, and the eduction of lightning from the skies, it appears that zinc was always found minus, and silver was always found plus, when both of them were in their separate state. Hence, when they are placed in the manner above described, as soon as their exterior edges come nearly into contact, so near as to have an extremely thin plate of air between them, that plate of air becomes charged in the same manner as a plate of coated glass; and is at the same instant discharged through the nerves of taste or of sight, and gives the sensations, as above described, of light or of saporocity; and only shews the great sensibility of these organs of sense to the stimulus of the electric fluid in suddenly passing through them. VI. _Of the Sense of Heat._ There are many experiments in chemical writers, that evince the existence of heat as a fluid element, which covers and pervades all bodies, and is attracted by the solutions of some of them, and is detruded from the combination of others. Thus from the combinations of metals with acids, and from those combinations of animal fluids, which are termed secretions, this fluid matter of heat is given out amongst the neighbouring bodies; and in the solutions of salts in water, or of water in air, it is absorbed from the bodies, that surround them; whilst in its facility in passing through metallic bodies, and its difficulty in pervading resins and glass, it resembles the properties of the electric aura; and is like that excited by friction, and seems like that to gravitate amongst other bodies in its uncombined state, and to find its equilibrium. There is no circumstance of more consequence in the animal economy than a due proportion of this fluid of heat; for the digestion of our nutriment in the stomach and bowels, and the proper qualities of all our secreted fluids, as they are produced or prepared partly by animal and partly by chemical processes, depend much on the quantity of heat; the excess of which, or its deficiency, alike gives us pain, and induces us to avoid the circumstances that occasion them. And in this the perception of heat essentially differs from the perceptions of the sense of touch, as we receive pain from too great pressure of solid bodies, but none from the absence of it. It is hence probable, that nature has provided us with a set of nerves for the perception of this fluid, which anatomists have not yet attended to. There may be some difficulty in the proof of this assertion; if we look at a hot fire, we experience no pain of the optic nerve, though the heat along with the light must be concentrated upon it. Nor does warm water or warm oil poured into the ear give pain to the organ of hearing; and hence as these organs of sense do not perceive small excesses or deficiences of heat; and as heat has no greater analogy to the solidity or to the figures of bodies, than it has to their colours or vibrations; there seems no sufficient reason for our ascribing the perception of heat and cold to the sense of touch; to which it has generally been attributed, either because it is diffused beneath the whole skin like the sense of touch, or owing to the inaccuracy of our observations, or the defect of our languages. There is another circumstance would induce us to believe, that the perceptions of heat and cold do not belong to the organ of touch; since the teeth, which are the least adapted for the perceptions of solidity or figure, are the most sensible to heat or cold; whence we are forewarned from swallowing those materials, whose degree of coldness or of heat would injure our stomachs. The following is an extract from a letter of Dr. R.W. Darwin, of Shrewsbury, when he was a student at Edinburgh. "I made an experiment yesterday in our hospital, which much favours your opinion, that the sensation of heat and of touch depend on different sets of nerves. A man who had lately recovered from a fever, and was still weak, was seized with violent cramps in his legs and feet; which were removed by opiates, except that one of his feet remained insensible. Mr. Ewart pricked him with a pin in five or six places, and the patient declared he did not feel it in the least, nor was he sensible of a very smart pinch. I then held a red-hot poker at some distance, and brought it gradually nearer till it came within three inches, when he asserted that he felt it quite distinctly. I suppose some violent irritation on the nerves of touch had caused the cramps, and had left them paralytic; while the nerves of heat, having suffered no increased stimulus, retained their irritability." Add to this, that the lungs, though easily stimulated into inflammation, are not sensible to heat. See Class. III. 1. 1. 10. VII. _Of the Sense of Extension._ The organ of touch is properly the sense of pressure, but the muscular fibres themselves constitute the organ of sense, that feels extension. The sense of pressure is always attended with the ideas of the figure and solidity of the object, neither of which accompany our perception of extension. The whole set of muscles, whether they are hollow ones, as the heart, arteries, and intestines, or longitudinal ones attached to bones, contract themselves, whenever they are stimulated by forcible elongation; and it is observable, that the white muscles, which constitute the arterial system, seem to be excited into contraction from no other kinds of stimulus, according to the experiments of Haller. And hence the violent pain in some inflammations, as in the paronychia, obtains immediate relief by cutting the membrane, that was stretched by the tumour of the subjacent parts. Hence the whole muscular system may be considered as one organ of sense, and the various attitudes of the body, as ideas belonging to this organ, of many of which we are hourly conscious, while many others, like the irritative ideas of the other senses, are performed without our attention. When the muscles of the heart cease to act, the refluent blood again distends or elongates them; and thus irritated they contract as before. The same happens to the arterial system, and I suppose to the capillaries, intestines, and various glands of the body. When the quantity of urine, or of excrement, distends the bladder, or rectum, those parts contract, and exclude their contents, and many other muscles by association act along with them; but if these evacuations are not soon complied with, pain is produced by a little further extension of the muscular fibres: a similar pain is caused in the muscles, when a limb is much extended for the reduction of dislocated bones; and in the punishment of the rack: and in the painful cramps of the calf of the leg, or of other muscles, for a greater degree of contraction of a muscle, than the movement of the two bones, to which its ends are affixed, will admit of, must give similar pain to that, which is produced by extending it beyond its due length. And the pain from punctures or incisions arises from the distention of the fibres, as the knife passes through them; for it nearly ceases as soon as the division is completed. All these motions of the muscles, that are thus naturally excited by the stimulus of distending bodies, are also liable to be called into strong action by their catenation, with the irritations or sensations produced by the momentum of the progressive particles of blood in the arteries, as in inflammatory fevers, or by acrid substances on other sensible organs, as in the strangury, or tenesmus, or cholera. We shall conclude this account of the sense of extension by observing, that the want of its object is attended with a disagreeable sensation, as well as the excess of it. In those hollow muscles, which have been accustomed to it, this disagreeable sensation is called faintness, emptiness, and sinking; and, when it arises to a certain degree, is attended with syncope, or a total quiescence of all motions, but the internal irritative ones, as happens from sudden loss of blood, or in the operation of tapping in the dropsy. VIII. _Of the Appetites of Hunger, Thirst, Heat, Extension, the want of fresh Air, animal Love, and the Suckling of Children._ Hunger is most probably perceived by those numerous ramifications of nerves that are seen about the upper opening of the stomach; and thirst by the nerves about the fauces, and the top of the gula. The ideas of these senses are few in the generality of mankind, but are more numerous in those, who by disease, or indulgence, desire particular kinds of foods or liquids. A sense of heat has already been spoken of, which may with propriety be called an appetite, as we painfully desire it, when it is deficient in quantity. The sense of extension may be ranked amongst these appetites, since the deficiency of its object gives disagreeable sensation; when this happens in the arterial system, it is called faintness, and seems to bear some analogy to hunger and to cold; which like it are attended with emptiness of a part of the vascular system. The sense of want of fresh air has not been attended to, but is as distinct as the others, and the first perhaps that we experience after our nativity; from the want of the object of this sense many diseases are produced, as the jail-fever, plague, and other epidemic maladies. Animal love is another appetite, which occurs later in life, and the females of lactiferous animals have another natural inlet of pleasure or pain from the suckling their offspring. The want of which either owing to the death of their progeny, or to the fashion of their country, has been fatal to many of the sex. The males have also pectoral glands, which are frequently turgid with a thin milk at their nativity, and are furnished with nipples, which erect on titillation like those of the female; but which seem now to be of no further use, owing perhaps to some change which these animals have undergone in the gradual progression of the formation of the earth, and of all that it inhabit. These seven last mentioned senses may properly be termed appetites, as they differ from those of touch, sight, hearing, taste, and smell, in this respect; that they are affected with pain as well by the defect of their objects as by the excess of them, which is not so in the latter. Thus cold and hunger give us pain, as well as an excess of heat or satiety; but it is not so with darkness and silence. IX. Before we conclude this Section on the organs of sense, we must observe, that, as far as we know, there are many more senses, than have been here mentioned, as every gland seems to be influenced to separate from the blood, or to absorb from the cavities of the body, or from the atmosphere, its appropriated fluid, by the stimulus of that fluid on the living gland; and not by mechanical capillary absorption, nor by chemical affinity. Hence it appears, that each of these glands must have a peculiar organ to perceive these irritations, but as these irritations are not succeeded by sensation, they have not acquired the names of senses. However when these glands are excited into motions stronger than usual, either by the acrimony of their fluids, or by their own irritability being much increased, then the sensation of pain is produced in them as in all the other senses of the body; and these pains are all of different kinds, and hence the glands at this time really become each a different organ of sense, though these different kinds of pain have acquired no names. Thus a great excess of light does not give the idea of light but of pain; as in forcibly opening the eye when it is much inflamed. The great excess of pressure or distention, as when the point of a pin is pressed upon our skin, produces pain, (and when this pain of the sense of distention is slighter, it is termed itching, or tickling), without any idea of solidity or of figure: an excess of heat produces smarting, of cold another kind of pain; it is probable by this sense of heat the pain produced by caustic bodies is perceived, and of electricity, as all these are fluids, that permeate, distend, or decompose the parts that feel them. * * * * * SECT. XV. OF THE CLASSES OF IDEAS. I. 1. _Ideas received in tribes._ 2. _We combine them further, or abstract from these tribes._ 3. _Complex ideas._ 4. _Compounded ideas._ 5. _Simple ideas, modes, substances, relations, general ideas._ 6. _Ideas of reflexion._ 7. _Memory and imagination imperfectly defined. Ideal presence. Memorandum-rings._ II. 1. _Irritative ideas. Perception._ 2. _Sensitive ideas, imagination._ 3. _Voluntary ideas, recollection._ 4. _Associated ideas, suggestion._ III. 1. _Definitions of perception, memory._ 2. _Reasoning, judgment, doubting, distinguishing, comparing._ 3. _Invention._ 4. _Consciousness._ 5. _Identity._ 6. _Lapse of time._ 7. _Free-will._ I. 1. As the constituent elements of the material world are only perceptible to our organs of sense in a state of combination; it follows, that the ideas or sensual motions excited by them, are never received singly, but ever with a greater or less degree of combination. So the colours of bodies or their hardnesses occur with their figures: every smell and taste has its degree of pungency as well as its peculiar flavour: and each note in music is combined with the tone of some instrument. It appears from hence, that we can be sensible of a number of ideas at the same time, such as the whiteness, hardness, and coldness, of a snow-ball, and can experience at the same time many irritative ideas of surrounding bodies, which we do not attend to, as mentioned in Section VII. 3. 2. But those ideas which belong to the same sense, seem to be more easily combined into synchronous tribes, than those which were not received by the same sense, as we can more easily think of the whiteness and figure of a lump of sugar at the same time, than the whiteness and sweetness of it. 2. As these ideas, or sensual motions, are thus excited with greater or less degrees of combination; so we have a power, when we repeat them either by our volition or sensation, to increase or diminish this degree of combination, that is, to form compounded ideas from those, which were more simple; and abstract ones from those, which were more complex, when they were first excited; that is, we can repeat a part or the whole of those sensual motions, which did constitute our ideas of perception; and the repetition of which now constitutes our ideas of recollection, or of imagination. 3. Those ideas, which we repeat without change of the quantity of that combination, with which we first received them, are called complex ideas, as when you recollect Westminster Abbey, or the planet Saturn: but it must be observed, that these complex ideas, thus re-excited by volition, sensation, or association, are seldom perfect copies of their correspondent perceptions, except in our dreams, where other external objects do not detract our attention. 4. Those ideas, which are more complex than the natural objects that first excited them, have been called compounded ideas, as when we think of a sphinx, or griffin. 5. And those that are less complex than the correspondent natural objects, have been termed abstracted ideas: thus sweetness, and whiteness, and solidity, are received at the same time from a lump of sugar, yet I can recollect any of these qualities without thinking of the others, that were excited along with them. When ideas are so far abstracted as in the above example, they have been termed simple by the writers of metaphysics, and seem indeed to be more complete repetitions of the ideas or sensual motions, originally excited by external objects. Other classes of these ideas, where the abstraction has not been so great, have been termed, by Mr. Locke, modes, substances, and relations, but they seem only to differ in their degree of abstraction from the complex ideas that were at first excited; for as these complex or natural ideas are themselves imperfect copies of their correspondent perceptions, so these abstract or general ideas are only still more imperfect copies of the same perceptions. Thus when I have seen an object but once, as a rhinoceros, my abstract idea of this animal is the same as my complex one. I may think more or less distinctly of a rhinoceros, but it is the very rhinoceros that I saw, or some part or property of him, which recurs to my mind. But when any class of complex objects becomes the subject of conversation, of which I have seen many individuals, as a castle or an army, some property or circumstance belonging to it is peculiarly alluded to; and then I feel in my own mind, that my abstract idea of this complex object is only an idea of that part, property, or attitude of it, that employs the present conversation, and varies with every sentence that is spoken concerning it. So if any one should say, "one may sit upon a horse safer than on a camel," my abstract idea of the two animals includes only an outline of the level back of the one, and the gibbosity on the back of the other. What noise is that in the street?--Some horses trotting over the pavement. Here my idea of the horses includes principally the shape and motion of their legs. So also the abstract ideas of goodness and courage are still more imperfect representations of the objects they were received from; for here we abstract the material parts, and recollect only the qualities. Thus we abstract so much from some of our complex ideas, that at length it becomes difficult to determine of what perception they partake; and in many instances our idea seems to be no other than of the sound or letters of the word, that stands for the collective tribe, of which we are said to have an abstracted idea, as noun, verb, chimæra, apparition. 6. Ideas have been divided into those of perception and those of reflection, but as whatever is perceived must be external to the organ that perceives it, all our ideas must originally be ideas of perception. 7. Others have divided our ideas into those of memory, and those of imagination; they have said that a recollection of ideas in the order they were received constitutes memory, and without that order imagination; but all the ideas of imagination, excepting the few that are termed simple ideas, are parts of trains or tribes in the order they were received; as if I think of a sphinx, or a griffin, the fair face, bosom, wings, claws, tail, are all complex ideas in the order they were received: and it behoves the writers, who adhere to this definition, to determine, how small the trains must be, that shall be called imagination; and how great those, that shall be called memory. Others have thought that the ideas of memory have a greater vivacity than those of imagination: but the ideas of a person in sleep, or in a waking reverie, where the trains connected with sensation are uninterrupted, are more vivid and distinct than those of memory, so that they cannot be distinguished by this criterion. The very ingenious author of the Elements of Criticism has described what he conceives to be a species of memory, and calls it ideal presence; but the instances he produces are the reveries of sensation, and are therefore in truth connections of the imagination, though they are recalled in the order they were received. The ideas connected by association are in common discourse attributed to memory, as we talk of memorandum-rings, and tie a knot on our handkerchiefs to bring something into our minds at a distance of time. And a school-boy, who can repeat a thousand unmeaning lines in Lilly's Grammar, is said to have a good memory. But these have been already shewn to belong to the class of association; and are termed ideas of suggestion. II. Lastly, the method already explained of classing ideas into those excited by irritation, sensation, volition, or association, we hope will be found more convenient both for explaining the operations of the mind, and for comparing them with those of the body; and for the illustration and the cure of the diseases of both, and which we shall here recapitulate. 1. Irritative ideas are those, which are preceded by irritation, which is excited by objects external to the organs of sense: as the idea of that tree, which either I attend to, or which I shun in walking near it without attention. In the former case it is termed perception, in the latter it is termed simply an irritative idea. 2. Sensitive ideas are those, which are preceded by the sensation of pleasure or pain; as the ideas, which constitute our dreams or reveries, this is called imagination. 3. Voluntary ideas are those, which are preceded by voluntary exertion, as when I repeat the alphabet backwards: this is called recollection. 4. Associate ideas are those, which are preceded by other ideas or muscular motions, as when we think over or repeat the alphabet by rote in its usual order; or sing a tune we are accustomed to; this is called suggestion. III. 1. Perceptions signify those ideas, which are preceded by irritation and succeeded by the sensation of pleasure or pain, for whatever excites our attention interests us; that is, it is accompanied with, pleasure or pain; however slight may be the degree or quantity of either of them. The word memory includes two classes of ideas, either those which, are preceded by voluntary exertion, or those which are suggested by their associations with other ideas. 2. Reasoning is that operation of the sensorium, by which we excite two or many tribes of ideas; and then re-excite the ideas, in which they differ, or correspond. If we determine this difference, it is called judgment; if we in vain endeavour to determine it, it is called doubting. If we re-excited the ideas, in which they differ, it is called distinguishing. If we re-excite those in which they correspond, it is called comparing. 3. Invention is an operation of the sensorium, by which we voluntarily continue to excite one train of ideas, suppose the design of raising water by a machine; and at the same time attend to all other ideas, which are connected with this by every kind of catenation; and combine or separate them voluntarily for the purpose of obtaining some end. For we can create nothing new, we can only combine or separate the ideas, which we have already received by our perceptions: thus if I wish to represent a monster, I call to my mind the ideas of every thing disagreeable and horrible, and combine the nastiness and gluttony of a hog, the stupidity and obstinacy of an ass, with the fur and awkwardness of a bear, and call the new combination Caliban. Yet such a monster may exist in nature, as all his attributes are parts of nature. So when I wish to represent every thing, that is excellent, and amiable; when I combine benevolence with cheerfulness, wisdom, knowledge, taste, wit, beauty of person, and elegance of manners, and associate them in one lady as a pattern to the world, it is called invention; yet such a person may exist,--such a person does exist!--It is ---- ----, who is as much a monster as Caliban. 4. In respect to consciousness, we are only conscious of our existence, when we think about it; as we only perceive the lapse of time, when we attend to it; when we are busied about other objects, neither the lapse of time nor the consciousness of our own existence can occupy our attention. Hence, when we think of our own existence, we only excite abstracted or reflex ideas (as they are termed), of our principal pleasures or pains, of our desires or aversions, or of the figure, solidity, colour, or other properties of our bodies, and call that act of the sensorium a consciousness of our existence. Some philosopher, I believe it is Des Cartes, has said, "I think, therefore I exist." But this is not right reasoning, because thinking is a mode of existence; and it is thence only saying, "I exist, therefore I exist." For there are three modes of existence, or in the language of grammarians three kinds of verbs. First, simply I am, or exist. Secondly, I am acting, or exist in a state of activity, as I move. Thirdly, I am suffering, or exist in a state of being acted upon, as I am moved. The when, and the where, as applicable to this existence, depends on the successive motions of our own or of other bodies; and on their respective situations, as spoken of Sect. XIV. 2. 5. 5. Our identity is known by our acquired habits or catenated trains of ideas and muscular motions; and perhaps, when we compare infancy with old age, in those alone can our identity be supposed to exist. For what else is there of similitude between the first speck of living entity and the mature man?--every deduction of reasoning, every sentiment or passion, with every fibre of the corporeal part of our system, has been subject almost to annual mutation; while some catenations alone of our ideas and muscular actions have continued in part unchanged. By the facility, with which we can in our waking hours voluntarily produce certain successive trains of ideas, we know by experience, that we have before reproduced them; that is, we are conscious of a time of our existence previous to the present time; that is, of our identity now and heretofore. It is these habits of action, these catenations of ideas and muscular motions, which begin with life, and only terminate with it; and which we can in some measure deliver to our posterity; as explained in Sect. XXXIX. 6. When the progressive motions of external bodies make a part of our present catenation of ideas, we attend to the lapse of time; which appears the longer, the more frequently we thus attend to it; as when we expect something at a certain hour, which much interests us, whether it be an agreeable or disagreeable event; or when we count the passing seconds on a stop-watch. When an idea of our own person, or a reflex idea of our pleasures and pains, desires and aversions, makes a part of this catenation, it is termed consciousness; and if this idea of consciousness makes a part of a catenation, which we excite by recollection, and know by the facility with which we excite it, that we have before experienced it, it is called identity, as explained above. 7. In respect to freewill, it is certain, that we cannot will to think of a new train of ideas, without previously thinking of the first link of it; as I cannot will to think of a black swan, without previously thinking of a black swan. But if I now think of a tail, I can voluntarily recollect all animals, which have tails; my will is so far free, that I can pursue the ideas linked to this idea of tail, as far as my knowledge of the subject extends; but to will without motive is to will without desire or aversion; which is as absurd as to feel without pleasure or pain; they are both solecisms in the terms. So far are we governed by the catenations of motions, which affect both the body and the mind of man, and which begin with our irritability, and end with it. * * * * * SECT. XVI. OF INSTINCT. Haud equidem credo, quia sit divinitus illis Ingenium, aut rerum fato prudentia major.--Virg. Georg. L. I. 415. I. _Instinctive actions defined. Of connate passions._ II. _Of the sensations and motions of the foetus in the womb._ III. _Some animals are more perfectly formed than others before nativity. Of learning to walk._ IV. _Of the swallowing, breathing, sucking, pecking, and lapping of young animals._ V. _Of the sense of smell, and its uses to animals. Why cats do not eat their kittens._ VI. _Of the accuracy of sight in mankind, and their sense of beauty. Of the sense of touch in elephants, monkies, beavers, men._ VII. _Of natural language._ VIII. _The origin of natural language;_ 1. _the language of fear;_ 2. _of grief;_ 3. _of tender pleasure;_ 4. _of serene pleasure;_ 5. _of anger;_ 6. _of attention._ IX. _Artificial language of turkies, hens, ducklings, wagtails, cuckoos, rabbits, dogs, and nightingales._ X. _Of music; of tooth-edge; of a good ear; of architecture._ XI. _Of acquired knowledge; of foxes, rooks, fieldfares, lapwings, dogs, cats, horses, crows, and pelicans._ XII. _Of birds of passage, dormice, snakes, bats, swallows, quails, ringdoves, stare, chaffinch, hoopoe, chatterer, hawfinch, crossbill, rails and cranes._ XIII. _Of birds nests; of the cuckoo; of swallows nests; of the taylor bird._ XIV. _Of the old soldier; of haddocks, cods, and dog fish; of the remora; of crabs, herrings, and salmon._ XV. _Of spiders, caterpillars, ants, and the ichneumon._ XVI. 1. _Of locusts, gnats;_ 2. _bees;_ 3. _dormice, flies, worms, ants, and wasps._ XVII. _Of the faculty that distinguishes man from the brutes._ I. All those internal motions of animal bodies, which contribute to digest their aliment, produce their secretions, repair their injuries, or increase their growth, are performed without our attention or consciousness. They exist as well in our sleep, as in our waking hours, as well in the foetus during the time of gestation, as in the infant after nativity, and proceed with equal regularity in the vegetable as in the animal system. These motions have been shewn in a former part of this work to depend on the irritations of peculiar fluids, and as they have never been classed amongst the instinctive actions of animals, are precluded from our present disquisition. But all those actions of men or animals, that are attended with consciousness, and seem neither to have been directed by their appetites, taught by their experience, nor deduced from observation or tradition, have been referred to the power of instinct. And this power has been explained to be a _divine something_, a kind of inspiration; whilst the poor animal, that possesses it, has been thought little better than _a machine_! The _irksomeness_, that attends a continued attitude of the body, or the _pains_, that we receive from heat, cold, hunger, or other injurious circumstances, excite us to _general locomotion_: and our senses are so formed and constituted by the hand of nature, that certain objects present us with pleasure, others with pain, and we are induced to approach and embrace these, to avoid and abhor those, as such sensations direct us. Thus the palates of some animals are gratefully affected by the mastication of fruits, others of grains, and others of flesh; and they are thence instigated to attain, and to consume those materials; and are furnished with powers of muscular motion, and of digestion proper for such purposes. These _sensations_ and _desires_ constitute a part of our system, as our _muscles_ and _bones_ constitute another part: and hence they may alike be termed _natural_ or _connate_; but neither of them can properly be termed _instinctive_: as the word instinct in its usual acceptation refers only to the _actions_ of animals, as above explained: the origin of these _actions_ is the subject of our present enquiry. The reader is intreated carefully to attend to this definition of _instinctive actions_, lest by using the word instinct without adjoining any accurate idea to it, he may not only include the natural desires of love and hunger, and the natural sensations of pain or pleasure, but the figure and contexture of the body, and the faculty of reason itself under this general term. II. We experience some sensations, and perform some actions before our nativity; the sensations of cold and warmth, agitation and rest, fulness and inanition, are instances of the former; and the repeated struggles of the limbs of the foetus, which begin about the middle of gestation, and those motions by which it frequently wraps the umbilical chord around its neck or body, and even sometimes ties it on a knot; are instances of the latter. Smellie's Midwifery, (Vol. I. p. 182.) By a due attention to these circumstances many of the actions of young animals, which at first sight seemed only referable to an inexplicable instinct, will appear to have been acquired like all other animal actions, that are attended with consciousness, _by the repeated efforts of our muscles under the conduct of our sensations or desires_. The chick in the shell begins to move its feet and legs on the sixth day of incubation (Mattreican, p. 138); or on the seventh day, (Langley); afterwards they are seen to move themselves gently in the liquid that surrounds them, and to open and shut their mouths, (Harvei, de Generat. p. 62, and 197. Form de Poulet. ii. p. 129). Puppies before the membranes are broken, that involve them, are seen to move themselves, to put out their tongues, and to open and shut their mouths, (Harvey, Gipson, Riolan, Haller). And calves lick themselves and swallow many of their hairs before their nativity: which however puppies do not, (Swammerden, p. 319. Flemyng Phil. Trans. Ann. 1755. 42). And towards the end of gestation, the foetus of all animals are proved to drink part of the liquid in which they swim, (Haller. Physiol. T. 8. 204). The white of egg is found in the mouth and gizzard of the chick, and is nearly or quite consumed before it is hatched, (Harvie de Generat. 58). And the liquor amnii is found in the mouth and stomach of the human foetus, and of calves; and how else should that excrement be produced in the intestines of all animals, which is voided in great quantity soon after their birth; (Gipson, Med. Essays, Edinb. V. i. 13. Halleri Physiolog. T. 3. p. 318. and T. 8). In the stomach of a calf the quantity of this liquid amounted to about three pints, and the hairs amongst it were of the same colour with those on its skin, (Blasii Anat. Animal, p.m. 122). These facts are attested by many other writers of credit, besides those above mentioned. III. It has been deemed a surprising instance of instinct, that calves and chickens should be able to walk by a few efforts almost immediately after their nativity: whilst the human infant in those countries where he is not incumbered with clothes, as in India, is five or six months, and in our climate almost a twelvemonth, before he can safely stand upon his feet. The struggles of all animals in the womb must resemble their mode of swimming, as by this kind of motion they can best change their attitude in water. But the swimming of the calf and chicken resembles their manner of walking, which they have thus in part acquired before their nativity, and hence accomplish it afterwards with very few efforts, whilst the swimming of the human creature resembles that of the frog, and totally differs from his mode of walking. There is another circumstance to be attended to in this affair, that not only the growth of those peculiar parts of animals, which are first wanted to secure their subsistence, are in general furthest advanced before their nativity: but some animals come into the world more completely formed throughout their whole system than others: and are thence much forwarder in all their habits of motion. Thus the colt, and the lamb, are much more perfect animals than the blind puppy, and the naked rabbit; and the chick of the pheasant, and the partridge, has more perfect plumage, and more perfect eyes, as well as greater aptitude to locomotion, than the callow nestlings of the dove, and of the wren. The parents of the former only find it necessary to shew them their food, and to teach them to take it up; whilst those of the latter are obliged for many days to obtrude it into their gaping mouths. IV. From the facts mentioned in No. 2. of this Section, it is evinced that the foetus learns to swallow before its nativity; for it is seen to open its mouth, and its stomach is found filled with the liquid that surrounds it. It opens its mouth, either instigated by hunger, or by the irksomeness of a continued attitude of the muscles of its face; the liquor amnii, in which it swims, is agreeable to its palate, as it consists of a nourishing material, (Haller Phys. T. 8. p. 204). It is tempted to experience its taste further in the mouth, and by a few efforts learns to swallow, in the same manner as we learn all other animal actions, which are attended with consciousness, _by the repeated efforts of our muscles under the conduct of our sensations or volitions_. The inspiration of air into the lungs is so totally different from that of swallowing a fluid in which we are immersed, that it cannot be acquired before our nativity. But at this time, when the circulation of the blood is no longer continued through the placenta, that suffocating sensation, which we feel about the precordia, when we are in want of fresh air, disagreeably affects the infant: and all the muscles of the body are excited into action to relieve this oppression; those of the breast, ribs, and diaphragm are found to answer this purpose, and thus respiration is discovered, and is continued throughout our lives, as often as the oppression begins to recur. Many infants, both of the human creature, and of quadrupeds, struggle for a minute after they are born before they begin to breathe, (Haller Phys. T. 8. p. 400. ib pt. 2. p. 1). Mr. Buffon thinks the action of the dry air upon the nerves of smell of new-born animals, by producing an endeavour to sneeze, may contribute to induce this first inspiration, and that the rarefaction of the air by the warmth of the lungs contributes to induce expiration, (Hist. Nat. Tom. 4. p. 174). Which latter it may effect by producing a disagreeable sensation by its delay, and a consequent effort to relieve it. Many children sneeze before they respire, but not all, as far as I have observed, or can learn from others. At length, by the direction of its sense of smell, or by the officious care of its mother, the young animal approaches the odoriferous rill of its future nourishment, already experienced to swallow. But in the act of swallowing, it is necessary nearly to close the mouth, whether the creature be immersed in the fluid it is about to drink, or not: hence, when the child first attempts to suck, it does not slightly compress the nipple between its lips, and suck as an adult person would do, by absorbing the milk; but it takes the whole nipple into its mouth for this purpose, compresses it between its gums, and thus repeatedly chewing (as it were) the nipple, presses out the milk, exactly in the same manner as it is drawn from the teats of cows by the hands of the milkmaid. The celebrated Harvey observes, that the foetus in the womb must have sucked in a part of its nourishment, because it knows how to suck the minute it is born, as any one may experience by putting a finger between its lips, and because in a few days it forgets this art of sucking, and cannot without some difficulty again acquire it, (Exercit. de Gener. Anim. 48). The same observation is made by Hippocrates. A little further experience teaches the young animal to suck by absorption, as well as by compression; that is, to open the chest as in the beginning of respiration, and thus to rarefy the air in the mouth, that the pressure of the denser external atmosphere may contribute to force out the milk. The chick yet in the shell has learnt to drink by swallowing a part of the white of the egg for its food; but not having experienced how to take up and swallow solid seeds, or grains, is either taught by the felicitous industry of its mother; or by many repeated attempts is enabled at length to distinguish and to swallow this kind of nutriment. And puppies, though they know how to suck like other animals from their previous experience in swallowing, and in respiration; yet are they long in acquiring the art of lapping with their tongues, which from the flaccidity of their cheeks, and length of their mouths, is afterwards a more convenient way for them to take in water. V. The senses of smell and taste in many other animals greatly excel those of mankind, for in civilized society, as our victuals are generally prepared by others, and are adulterated with salt, spice, oil, and empyreuma, we do not hesitate about eating whatever is set before us, and neglect to cultivate these senses: whereas other animals try every morsel by the smell, before they take it into their mouths, and by the taste before they swallow it: and are led not only each to his proper nourishment by this organ of sense, but it also at a maturer age directs them in the gratification of their appetite of love. Which may be further understood by considering the sympathies of these parts described in Class IV. 2. 1. 7. While the human animal is directed to the object of his love by his sense of beauty, as mentioned in No. VI. of this Section. Thus Virgil. Georg. III. 250. Nonne vides, ut tota tremor pertentat equorum Corpora, si tantum notas odor attulit auras? Nonne canis nidum veneris nasutus odore Quærit, et erranti trahitur sublambere linguâ? Respuit at gustum cupidus, labiisque retractis Elevat os, trepidansque novis impellitur æstris Inserit et vivum felici vomere semen.-- Quam tenui filo cæcos adnectit amores Docta Venus, vitæque monet renovare favillam!--ANON. The following curious experiment is related by Galen. "On dissecting a goat great with young I found a brisk embryon, and having detached it from the matrix, and snatching it away before it saw its dam, I brought it into a certain room, where there were many vessels, some filled with wine, others with oil, some with honey, others with milk, or some other liquor; and in others were grains and fruits; we first observed the young animal get upon its feet, and walk; then it shook itself, and afterwards scratched its side with one of its feet: then we saw it smelling to every one of these things, that were set in the room; and when it had smelt to them all, it drank up the milk." L. 6. de locis. cap. 6. Parturient quadrupeds, as cats, and bitches, and sows, are led by their sense of smell to eat the placenta as other common food; why then do they not devour their whole progeny, as is represented in an antient emblem of TIME? This is said sometimes to happen in the unnatural state in which we confine sows; and indeed nature would seem to have endangered her offspring in this nice circumstance! But at this time the stimulus of the milk in the tumid teats of the mother excites her to look out for, and to desire some unknown circumstance to relieve her. At the same time the smell of the milk attracts the exertions of the young animals towards its source, and thus the delighted mother discovers a new appetite, as mentioned in Sect. XIV. 8. and her little progeny are led to receive and to communicate pleasure by this most beautiful contrivance. VI. But though the human species in some of their sensations are much inferior to other animals, yet the accuracy of the sense of touch, which they possess in so eminent a degree, gives them a great superiority of understanding; as is well observed by the ingenious Mr. Buffon. The extremities of other animals terminate in horns, and hoofs, and claws, very unfit for the sensation of touch; whilst the human hand is finely adapted to encompass its object with this organ of sense. The elephant is indeed endued with a fine sense of feeling at the extremity of his proboscis, and hence has acquired much more accurate ideas of touch and of sight than most other creatures. The two following instances of the sagacity of these animals may entertain the reader, as they were told me by some gentlemen of distinct observation, and undoubted veracity, who had been much conversant with our eastern settlements. First, the elephants that are used to carry the baggage of our armies, are put each under the care of one of the natives of Indostan, and whilst himself and his wife go into the woods to collect leaves and branches of trees for his food, they fix him to the ground by a length of chain, and frequently leave a child yet unable to walk, under his protection: and the intelligent animal not only defends it, but as it creeps about, when it arrives near the extremity of his chain, he wraps his trunk gently round its body, and brings it again into the centre of his circle. Secondly, the traitor elephants are taught to walk on a narrow path between two pit-falls, which are covered with turf, and then to go into the woods, and to seduce the wild elephants to come that way, who fall into these wells, whilst he passes safe between them: and it is universally observed, that those wild elephants that escape the snare, pursue the traitor with the utmost vehemence, and if they can overtake him, which sometimes happens, they always beat him to death. The monkey has a hand well enough adapted for the sense of touch, which contributes to his great facility of imitation; but in taking objects with his hands, as a stick or an apple, he puts his thumb on the same side of them with his fingers, instead of counteracting the pressure of his fingers with it: from this neglect he is much slower in acquiring the figures of objects, as he is less able to determine the distances or diameters of their parts, or to distinguish their vis inertiæ from their hardness. Helvetius adds, that the shortness of his life, his being fugitive before mankind, and his not inhabiting all climates, combine to prevent his improvement. (De l'Esprit. T. 1. p.) There is however at this time an old monkey shewn in Exeter Change, London, who having lost his teeth, when nuts are given him, takes a stone into his hand, and cracks them with it one by one; thus using tools to effect his purpose like mankind. The beaver is another animal that makes much use of his hands, and if we may credit the reports of travellers, is possessed of amazing ingenuity. This however, M. Buffon affirms, is only where they exist in large numbers, and in countries thinly peopled with men; while in France in their solitary state they shew no uncommon ingenuity. Indeed all the quadrupeds, that have collar-bones, (claviculæ) use their fore-limbs in some measure as we use our hands, as the cat, squirrel, tyger, bear and lion; and as they exercise the sense of touch more universally than other animals, so are they more sagacious in watching and surprising their prey. All those birds, that use their claws for hands, as the hawk, parrot, and cuckoo, appear to be more docile and intelligent; though the gregarious tribes of birds have more acquired knowledge. Now as the images, that are painted on the retina of the eye, are no other than signs, which recall to our imaginations the objects we had before examined by the organ of touch, as is fully demonstrated by Dr. Berkley in his treatise on vision; it follows that the human creature has greatly more accurate and distinct sense of vision than that of any other animal. Whence as he advances to maturity he gradually acquires a sense of female beauty, which at this time directs him to the object of his new passion. Sentimental love, as distinguished from the animal passion of that name, with which it is frequently accompanied, consists in the desire or sensation of beholding, embracing, and saluting a beautiful object. The characteristic of beauty therefore is that it is the object of love; and though many other objects are in common language called beautiful, yet they are only called so metaphorically, and ought to be termed agreeable. A Grecian temple may give us the pleasurable idea of sublimity, a Gothic temple may give us the pleasurable idea of variety, and a modern house the pleasurable idea of utility; music and poetry may inspire our love by association of ideas; but none of these, except metaphorically, can be termed beautiful; as we have no wish to embrace or salute them. Our perception of beauty consists in our recognition by the sense of vision of those objects, first, which have before inspired our love by the pleasure, which they have afforded to many of our senses: as to our sense of warmth, of touch, of smell, of taste, hunger and thirst; and, secondly, which bear any analogy of form to such objects. When the babe, soon after it is born into this cold world, is applied to its mother's bosom; its sense of perceiving warmth is first agreeably affected; next its sense of smell is delighted with the odour of her milk; then its taste is gratified by the flavour of it: afterwards the appetites of hunger and of thirst afford pleasure by the possession of their objects, and by the subsequent digestion of the aliment; and, lastly, the sense of touch is delighted by the softness and smoothness of the milky fountain, the source of such variety of happiness. All these various kinds of pleasure at length become associated with the form of the mother's breast; which the infant embraces with its hands, presses with its lips, and watches with its eyes; and thus acquires more accurate ideas of the form of its mother's bosom, than of the odour and flavour or warmth, which it perceives by its other senses. And hence at our maturer years, when any object of vision is presented to us, which by its waving or spiral lines bears any similitude to the form of the female bosom, whether it be found in a landscape with soft gradations of rising and descending surface, or in the forms of some antique vases, or in other works of the pencil or the chissel, we feel a general glow of delight, which seems to influence all our senses; and, if the object be not too large, we experience an attraction to embrace it with our arms, and to salute it with our lips, as we did in our early infancy the bosom of our mother. And thus we find, according to the ingenious idea of Hogarth, that the waving lines of beauty were originally taken from the temple of Venus. This animal attraction is love; which is a sensation, when the object is present; and a desire, when it is absent. Which constitutes the purest source of human felicity, the cordial drop in the otherwise vapid cup of life, and which overpays mankind for the care and labour, which are attached to the pre-eminence of his situation above other animals. It should have been observed, that colour as well as form sometimes enters into our idea of a beautiful object, as a good complexion for instance, because a fine or fair colour is in general a sign of health, and conveys to us an idea of the warmth of the object; and a pale countenance on the contrary gives an idea of its being cold to the touch. It was before remarked, that young animals use their lips to distinguish the forms of things, as well as their fingers, and hence we learn the origin of our inclination to salute beautiful objects with our lips. For a definition of Grace, see Class III. 1. 2. 4. VII. There are two ways by which we become acquainted with the passions of others: first, by having observed the effects of them, as of fear or anger, on our own bodies, we know at sight when others are under the influence of these affections. So when two cocks are preparing to fight, each feels the feathers rise round his own neck, and knows from the same sign the disposition of his adversary: and children long before they can speak, or understand the language of their parents, may be frightened by an angry countenance, or soothed by smiles and blandishments. Secondly, when we put ourselves into the attitude that any passion naturally occasions, we soon in some degree acquire that passion; hence when those that scold indulge themselves in loud oaths, and violent actions of the arms, they increase their anger by the mode of expressing themselves: and on the contrary the counterfeited smile of pleasure in disagreeable company soon brings along with it a portion of the reality, as is well illustrated by Mr. Burke. (Essay on the Sublime and Beautiful.) This latter method of entering into the passions of others is rendered of very extensive use by the pleasure we take in imitation, which is every day presented before our eyes, in the actions of children, and indeed in all the customs and fashions of the world. From this our aptitude to imitation, arises what is generally understood by the word sympathy so well explained by Dr. Smith of Glasgow. Thus the appearance of a cheerful countenance gives us pleasure, and of a melancholy one makes us sorrowful. Yawning and sometimes vomiting are thus propagated by sympathy, and some people of delicate fibres, at the presence of a spectacle of misery, have felt pain in the same parts of their own bodies, that were diseased or mangled in the other. Amongst the writers of antiquity Aristotle thought this aptitude to imitation an essential property of the human species, and calls man an imitative animal. [Greek: To zôon mimômenon]. These then are the natural signs by which we understand each other, and on this slender basis is built all human language. For without some natural signs, no artificial ones could have been invented or understood, as is very ingeniously observed by Dr. Reid. (Inquiry into the Human Mind.) VIII. The origin of this universal language is a subject of the highest curiosity, the knowledge of which has always been thought utterly inaccessible. A part of which we shall however here attempt. Light, sound, and odours, are unknown to the foetus in the womb, which, except the few sensations and motions already mentioned, sleeps away its time insensible of the busy world. But the moment he arrives into day, he begins to experience many vivid pains and pleasures; these are at the same time attended with certain muscular motions, and from this their early, and individual association, they acquire habits of occurring together, that are afterwards indissoluble. 1. _Of Fear._ As soon as the young animal is born, the first important sensations, that occur to him, are occasioned by the oppression about his precordia for want of respiration, and by his sudden transition from ninety-eight degrees of heat into so cold a climate.--He trembles, that is, he exerts alternately all the muscles of his body, to enfranchise himself from the oppression about his bosom, and begins to breathe with frequent and short respirations; at the same time the cold contracts his red skin, gradually turning it pale; the contents of the bladder and of the bowels are evacuated: and from the experience of these first disagreeable sensations the passion of fear is excited, which is no other than the expectation of disagreeable sensations. This early association of motions and sensations persists throughout life; the passion of fear produces a cold and pale skin, with tremblings, quick respiration, and an evacuation of the bladder and bowels, and thus constitutes the natural or universal language of this passion. On observing a Canary bird this morning, January 28, 1772, at the house of Mr. Harvey, near Tutbury, in Derbyshire, I was told it always fainted away, when its cage was cleaned, and desired to see the experiment. The cage being taken from the ceiling, and its bottom drawn out, the bird began to tremble, and turned quite white about the root of his bill: he then opened his mouth as if for breath, and respired quick, stood straighter up on his perch, hung his wings, spread his tail, closed his eyes, and appeared quite stiff and cataleptic for near half an hour, and at length with much trembling and deep respirations came gradually to himself. 2. _Of Grief._ That the internal membrane of the nostrils may be kept always moist, for the better perception of odours, there are two canals, that conduct the tears after they have done their office in moistening and cleaning the ball of the eye into a sack, which is called the lacrymal sack; and from which there is a duct, that opens into the nostrils: the aperture of this duct is formed of exquisite sensibility, and when it is stimulated by odorous particles, or by the dryness or coldness of the air, the sack contracts itself, and pours more of its contained moisture on the organ of smell. By this contrivance the organ is rendered more fit for perceiving such odours, and is preserved from being injured by those that are more strong or corrosive. Many other receptacles of peculiar fluids disgorge their contents, when the ends of their ducts are stimulated; as the gall bladder, when the contents of the duodenum stimulate the extremity of the common bile duct: and the salivary glands, when the termination of their ducts in the mouth are excited by the stimulus of the food we masticate. Atque vesiculæ seminales suum exprimunt fluidum glande penis fricatâ. The coldness and dryness of the atmosphere, compared with the warmth and moisture, which the new-born infant had just before experienced, disagreeably affects the aperture of this lacrymal sack: the tears, that are contained in this sack, are poured into the nostrils, and a further supply is secreted by the lacrymal glands, and diffused upon the eye-balls; as is very visible in the eyes and nostrils of children soon after their nativity. The same happens to us at our maturer age, for in severe frosty weather, snivelling and tears are produced by the coldness and dryness of the air. But the lacrymal glands, which separate the tears from the blood, are situated on the upper external part of the globes of each eye; and, when a greater quantity of tears are wanted, we contract the forehead, and bring down the eye-brows, and use many other distortions of the face, to compress these glands. Now as the suffocating sensation, that produces respiration, is removed almost as soon as perceived, and does not recur again: this disagreeable irritation of the lacrymal ducts, as it must frequently recur, till the tender organ becomes used to variety of odours, is one of the first pains that is repeatedly attended to: and hence throughout our infancy, and in many people throughout their lives, all disagreeable sensations are attended with snivelling at the nose, a profusion of tears, and some peculiar distortions of countenance: according to the laws of early association before mentioned, which constitutes the natural or universal language of grief. You may assure yourself of the truth of this observation, if you will attend to what passes, when you read a distressful tale alone; before the tears overflow your eyes, you will invariably feel a titillation at that extremity of the lacrymal duct, which terminates in the nostril, then the compression of the eyes succeeds, and the profusion of tears. Linnæus asserts, that the female bear sheds tears in grief; the same has been said of the hind, and some other animals. 3. _Of Tender Pleasure._ The first most lively impression of pleasure, that the infant enjoys after its nativity, is excited by the odour of its mother's milk. The organ of smell is irritated by this perfume, and the lacrymal sack empties itself into the nostrils, as before explained, and an increase of tears is poured into the eyes. Any one may observe this, when very young infants are about to suck; for at those early periods of life, the sensation affects the organ of smell, much more powerfully, than after the repeated habits of smelling has inured it to odours of common strength: and in our adult years, the stronger smells, though they are at the same time agreeable to us, as of volatile spirits, continue to produce an increased secretion of tears. This pleasing sensation of smell is followed by the early affection of the infant to the mother that suckles it, and hence the tender feelings of gratitude and love, as well as of hopeless grief, are ever after joined with the titillation of the extremity of the lacrymal ducts, and a profusion of tears. Nor is it singular, that the lacrymal sack should be influenced by pleasing ideas, as the sight of agreeable food produces the same effect on the salivary glands. Ac dum vidimus insomniis lascivæ puellæ simulacrum tenditur penis. Lambs shake or wriggle their tails, at the time when they first suck, to get free of the hard excrement, which had been long lodged in their bowels. Hence this becomes afterwards a mark of pleasure in them, and in dogs, and other tailed animals. But cats gently extend and contract their paws when they are pleased, and purr by drawing in their breath, both which resemble their manner of sucking, and thus become their language of pleasure, for these animals having collar-bones use their paws like hands when they suck, which dogs and sheep do not. 4. _Of Serene Pleasure._ In the action of sucking, the lips of the infant are closed around the nipple of its mother, till he has filled his stomach, and the pleasure occasioned by the stimulus of this grateful food succeeds. Then the sphincter of the mouth, fatigued by the continued action of sucking, is relaxed; and the antagonist muscles of the face gently acting, produce the smile of pleasure: as cannot but be seen by all who are conversant with children. Hence this smile during our lives is associated with gentle pleasure; it is visible in kittens, and puppies, when they are played with, and tickled; but more particularly marks the human features. For in children this expression of pleasure is much encouraged, by their imitation of their parents, or friends; who generally address them with a smiling countenance: and hence some nations are more remarkable for the gaiety, and others for the gravity of their looks. 5. _Of Anger._ The actions that constitute the mode of fighting, are the immediate language of anger in all animals; and a preparation for these actions is the natural language of threatening. Hence the human creature clenches his fist, and sternly surveys his adversary, as if meditating where to make the attack; the ram, and the bull, draws himself some steps backwards, and levels his horns; and the horse, as he most frequently fights by striking with his hinder feet, turns his heels to his foe, and bends back his ears, to listen out the place of his adversary, that the threatened blow may not be ineffectual. 6. _Of Attention._ The eye takes in at once but half our horizon, and that only in the day, and our smell informs us of no very distant objects, hence we confide principally in the organ of hearing to apprize us of danger: when we hear any the smallest sound, that we cannot immediately account for, our fears are alarmed, we suspend our steps, hold every muscle still, open our mouths a little, erect our ears, and listen to gain further information: and this by habit becomes the general language of attention to objects of sight, as well as of hearing; and even to the successive trains of our ideas. The natural language of violent pain, which is expressed by writhing the body, grinning, and screaming; and that of tumultuous pleasure, expressed in loud laughter; belong to Section XXXIV. on Diseases from Volition. IX. It must have already appeared to the reader, that all other animals, as well as man, are possessed of this natural language of the passions, expressed in signs or tones; and we shall endeavour to evince, that those animals, which have preserved themselves from being enslaved by mankind, and are associated in flocks, are also possessed of some artificial language, and of some traditional knowledge. The mother-turkey, when she eyes a kite hovering high in air, has either seen her own parents thrown into fear at his presence, or has by observation been acquainted with his dangerous designs upon her young. She becomes agitated with fear, and uses the natural language of that passion, her young ones catch the fear by imitation, and in an instant conceal themselves in the grass. At the same time that she shews her fears by her gesture and deportment, she uses a certain exclamation, Koe-ut, Koe-ut, and the young ones afterwards know, when they hear this note, though they do not see their dam, that the presence of their adversary is denounced, and hide themselves as before. The wild tribes of birds have very frequent opportunities of knowing their enemies, by observing the destruction they make among their progeny, of which every year but a small part escapes to maturity: but to our domestic birds these opportunities so rarely occur, that their knowledge of their distant enemies must frequently be delivered by tradition in the manner above explained, through many generations. This note of danger, as well as the other notes of the mother-turkey, when she calls her flock to their food, or to sleep under her wings, appears to be an artificial language, both as expressed by the mother, and as understood by the progeny. For a hen teaches this language with equal ease to the ducklings, she has hatched from suppositious eggs, and educates as her own offspring: and the wagtails, or hedge-sparrows, learn it from the young cuckoo their softer nursling, and supply him with food long after he can fly about, whenever they hear his cuckooing, which Linnæus tells us, is his call of hunger, (Syst. Nat.) And all our domestic animals are readily taught to come to us for food, when we use one tone of voice, and to fly from our anger, when we use another. Rabbits, as they cannot easily articulate sounds, and are formed into societies, that live under ground, have a very different method of giving alarm. When danger is threatened, they thump on the ground with one of their hinder feet, and produce a sound, that can be heard a great way by animals near the surface of the earth, which would seem to be an artificial sign both from its singularity and its aptness to the situation of the animal. The rabbits on the island of Sor, near Senegal, have white flesh, and are well tasted, but do not burrow in the earth, so that we may suspect their digging themselves houses in this cold climate is an acquired art, as well as their note of alarm, (Adanson's Voyage to Senegal). The barking of dogs is another curious note of alarm, and would seem to be an acquired language, rather than a natural sign: for "in the island of Juan Fernandes, the dogs did not attempt to bark, till some European dogs were put among them, and then they gradually begun to imitate them, but in a strange manner at first, as if they were learning a thing that was not natural to them," (Voyage to South America by Don G. Juan, and Don Ant. de Ulloa. B. 2. c. 4). Linnæus also observes, that the dogs of South America do not bark at strangers, (Syst. Nat.) And the European dogs, that have been carried to Guinea, are said in three or four generations to cease to bark, and only howl, like the dogs that are natives of that coast, (World Displayed, Vol. XVII. p. 26.) A circumstance not dissimilar to this, and equally curious, is mentioned by Kircherus, de Musurgia, in his Chapter de Lusciniis, "That the young nightingales, that are hatched under other birds, never sing till they are instructed by the company of other nightingales." And Jonston affirms, that the nightingales that visit Scotland, have not the same harmony as those of Italy, (Pennant's Zoology, octavo, p. 255); which would lead us to suspect that the singing of birds, like human music, is an artificial language rather than a natural expression of passion. X. Our music like our language, is perhaps entirely constituted of artificial tones, which by habit suggest certain agreeable passions. For the same combination of notes and tones do not excite devotion, love, or poetic melancholy in a native of Indostan and of Europe. And "the Highlander has the same warlike ideas annexed to the sound of a bagpipe (an instrument which an Englishman derides), as the Englishman has to that of a trumpet or fife," (Dr. Brown's Union of Poetry and Music, p. 58.) So "the music of the Turks is very different from the Italian, and the people of Fez and Morocco have again a different kind, which to us appears very rough and horrid, but is highly pleasing to them," (L'Arte Armoniaca a Giorgio Antoniotto). Hence we see why the Italian opera does not delight an untutored Englishman; and why those, who are unaccustomed to music, are more pleased with a tune, the second or third time they hear it, than the first. For then the same melodious train of sounds excites the melancholy, they had learned from the song; or the same vivid combination of them recalls all the mirthful ideas of the dance and company. Even the sounds, that were once disagreeable to us, may by habit be associated with other ideas, so as to become agreeable. Father Lasitau, in his account of the Iroquois, says "the music and dance of those Americans, have something in them extremely barbarous, which at first disgusts. We grow reconciled to them by degrees, and in the end partake of them with pleasure, the savages themselves are fond of them to distraction," (Moeurs des Savages, Tom. ii.) There are indeed a few sounds, that we very generally associate with agreeable ideas, as the whistling of birds, or purring of animals, that are delighted; and some others, that we as generally associate with disagreeable ideas, as the cries of animals in pain, the hiss of some of them in anger, and the midnight howl of beasts of prey. Yet we receive no terrible or sublime ideas from the lowing of a cow, or the braying of an ass. Which evinces, that these emotions are owing to previous associations. So if the rumbling of a carriage in the street be for a moment mistaken for thunder, we receive a sublime sensation, which ceases as soon as we know it is the noise of a coach and six. There are other disagreeable sounds, that are said to set the teeth on edge; which, as they have always been thought a necessary effect of certain discordant notes, become a proper subject of our enquiry. Every one in his childhood has repeatedly bit a part of the glass or earthen vessel, in which his food has been given him, and has thence had a very disagreeable sensation in the teeth, which sensation was designed by nature to prevent us from exerting them on objects harder than themselves. The jarring sound produced between the cup and the teeth is always attendant on this disagreeable sensation: and ever after when such a sound is accidentally produced by the conflict of two hard bodies, we feel by association of ideas the concomitant disagreeable sensation in our teeth. Others have in their infancy frequently held the corner of a silk handkerchief in their mouth, or the end of the velvet cape of their coat, whilst their companions in play have plucked it from them, and have given another disagreeable sensation to their teeth, which has afterwards recurred on touching those materials. And the sight of a knife drawn along a china plate, though no sound is excited by it, and even the imagination of such a knife and plate so scraped together, I know by repeated experience will produce the same disagreeable sensation of the teeth. These circumstances indisputably prove, that this sensation of the tooth-edge is owing to associated ideas; as it is equally excitable by sight, touch, hearing, or imagination. In respect to the artificial proportions of sound excited by musical instruments, those, who have early in life associated them with agreeable ideas, and have nicely attended to distinguish them from each other, are said to have a good ear, in that country where such proportions are in fashion: and not from any superior perfection in the organ of hearing, or any intuitive sympathy between certain sounds and passions. I have observed a child to be exquisitely delighted with music, and who could with great facility learn to sing any tune that he heard distinctly, and yet whole organ of hearing was so imperfect, that it was necessary to speak louder to him in common conversation than to others. Our music, like our architecture, seems to have no foundation in nature, they are both arts purely of human creation, as they imitate nothing. And the professors of them have only classed those circumstances, that are most agreeable to the accidental taste of their age, or country; and have called it Proportion. But this proportion must always fluctuate, as it rests on the caprices, that are introduced into our minds by our various modes of education. And these fluctuations of taste must become more frequent in the present age, where mankind have enfranchised themselves from the blind obedience to the rules of antiquity in perhaps every science, but that of architecture. See Sect. XII. 7. 3. XI. There are many articles of knowledge, which the animals in cultivated countries seem to learn very early in their lives, either from each other, or from experience, or observation: one of the most general of these is to avoid mankind. There is so great a resemblance in the natural language of the passions of all animals, that we generally know, when they are in a pacific, or in a malevolent humour, they have the same knowledge of us; and hence we can scold them from us by some tones and gestures, and could possibly attract them to us by others, if they were not already apprized of our general malevolence towards them. Mr. Gmelin, Professor at Petersburg, assures us, that in his journey into Siberia, undertaken by order of the Empress of Russia, he saw foxes, that expressed no fear of himself or companions, but permitted him to come quite near them, having never seen the human creature before. And Mr. Bongainville relates, that at his arrival at the Malouine, or Falkland's Islands, which were not inhabited by men, all the animals came about himself and his people; the fowls settling upon their heads and shoulders, and the quadrupeds running about their feet. From the difficulty of acquiring the confidence of old animals, and the ease of taming young ones, it appears that the fear, they all conceive at the sight of mankind, is an acquired article of knowledge. This knowledge is more nicely understood by rooks, who are formed into societies, and build, as it were, cities over our heads; they evidently distinguish, that the danger is greater when a man is armed with a gun. Every one has seen this, who in the spring of the year has walked under a rookery with a gun in his hand: the inhabitants of the trees rise on their wings, and scream to the unfledged young to shrink into their nests from the sight of the enemy. The vulgar observing this circumstance so uniformly to occur, assert that rooks can smell gun-powder. The fieldfares, (turdus pilarus) which breed in Norway, and come hither in the cold season for our winter berries; as they are associated in flocks, and are in a foreign country, have evident marks of keeping a kind of watch, to remark and announce the appearance of danger. On approaching a tree, that is covered with them, they continue fearless till one at the extremity of the bush rising on his wings gives a loud and peculiar note of alarm, when they all immediately fly, except one other, who continues till you approach still nearer, to certify as it were the reality of the danger, and then he also flies off repeating the note of alarm. And in the woods about Senegal there is a bird called uett-uett by the negroes, and squallers by the French, which, as soon as they see a man, set up a loud scream, and keep flying round him, as if their intent was to warn other birds, which upon hearing the cry immediately take wing. These birds are the bane of sportsmen, and frequently put me into a passion, and obliged me to shoot them, (Adanson's Voyage to Senegal, 78). For the same intent the lesser birds of our climate seem to fly after a hawk, cuckoo, or owl, and scream to prevent their companions from being surprised by the general enemies of themselves, or of their eggs and progeny. But the lapwing, (charadrius pluvialis Lin.) when her unfledged offspring run about the marshes, where they were hatched, not only gives the note of alarm at the approach of men or dogs, that her young may conceal themselves; but flying and screaming near the adversary, she appears more felicitous and impatient, as he recedes from her family, and thus endeavours to mislead him, and frequently succeeds in her design. These last instances are so apposite to the situation, rather than to the natures of the creatures, that use them; and are so similar to the actions of men in the same circumstances, that we cannot but believe, that they proceed from a similar principle. Miss M.E. Jacson acquainted me, that she witnessed this autumn an agreeable instance of sagacity in a little bird, which seemed to use the means to obtain an end; the bird repeatedly hopped upon a poppy-stem, and shook the head with its bill, till many seeds were scattered, then it settled on the ground, and eat the seeds, and again repeated the same management. Sept. 1, 1794. On the northern coast of Ireland a friend of mine saw above a hundred crows at once preying upon muscles; each crow took a muscle up into the air twenty or forty yards high, and let it fall on the stones, and thus by breaking the shell, got possession of the animal.--A certain philosopher (I think it was Anaxagoras) walking along the sea-shore to gather shells, one of these unlucky birds mistaking his bald head for a stone, dropped a shell-fish upon it, and killed at once a philosopher and an oyster. Our domestic animals, that have some liberty, are also possessed of some peculiar traditional knowledge: dogs and cats have been forced into each other's society, though naturally animals of a very different kind, and have hence learned from each other to eat dog's grass (agrostis canina) when they are sick, to promote vomiting. I have seen a cat mistake the blade of barley for this grass, which evinces it is an acquired knowledge. They have also learnt of each other to cover their excrement and urine;--about a spoonful of water was spilt upon my hearth from the tea-kettle, and I observed a kitten cover it with ashes. Hence this must also be an acquired art, as the creature mistook the application of it. To preserve their fur clean, and especially their whiskers, cats wash their faces, and generally quite behind their ears, every time they eat. As they cannot lick those places with their tongues, they first wet the inside of the leg with saliva, and then repeatedly wash their faces with it, which must originally be an effect of reasoning, because a means is used to produce an effect; and seems afterwards to be taught or acquired by imitation, like the greatest part of human arts. These animals seem to possess something like an additional sense by means of their whiskers; which have perhaps some analogy to the antennæ of moths and butterflies. The whiskers of cats consist not only of the long hairs on their upper lips, but they have also four or five long hairs standing up from each eyebrow, and also two or three on each cheek; all which, when the animal erects them, make with their points so many parts of the periphery of a circle, of an extent at least equal to the circumference of any part of their own bodies. With this instrument, I conceive, by a little experience, they can at once determine, whether any aperture amongst hedges or shrubs, in which animals of this genus live in their wild state, is large enough to admit their bodies; which to them is a matter of the greatest consequence, whether pursuing or pursued. They have likewise a power of erecting and bringing forward the whiskers on their lips; which probably is for the purpose of feeling, whether a dark hole be further permeable. The antennæ, or horns, of butterflies and moths, who have awkward wings, the minute feathers of which are very liable to injury, serve, I suppose, a similar purpose of measuring, as they fly or creep amongst the leaves of plants and trees, whither their wings can pass without touching them. Mr. Leonard, a very intelligent friend of mine, saw a cat catch a trout by darting upon it in a deep clear water at the mill at Weaford, near Lichfield. The cat belonged to Mr. Stanley, who had often seen her catch fish in the same manner in summer, when the mill-pool was drawn so low, that the fish could be seen. I have heard of other cats taking fish in shallow water, as they stood on the bank. This seems a natural art of taking their prey in cats, which their acquired delicacy by domestication has in general prevented them from using, though their desire of eating fish continues in its original strength. Mr. White, in his ingenious History of Selbourn, was witness to a cat's suckling a young hare, which followed her about the garden, and came jumping to her call of affection. At Elford, near Lichfield, the Rev. Mr. Sawley had taken the young ones out of a hare, which was shot; they were alive, and the cat, who had just lost her own kittens, carried them away, as it was supposed, to eat them; but it presently appeared, that it was affection not hunger which incited her, as she suckled them, and brought them up as their mother. Other instances of the mistaken application of what has been termed instinct may be observed in flies in the night, who mistaking a candle for day-light, approach and perish in the flame. So the putrid smell of the stapelia, or carrion-flower, allures the large flesh-fly to deposit its young worms on its beautiful petals, which perish there for want of nourishment. This therefore cannot be a necessary instinct, because the creature mistakes the application of it. Though in this country horses shew little vestiges of policy, yet in the deserts of Tartary, and Siberia, when hunted by the Tartars they are seen to form a kind of community, set watches to prevent their being surprised, and have commanders, who direct, and hasten their flight, Origin of Language, Vol. I. p. 212. In this country, where four or five horses travel in a line, the first always points his ears forward, and the last points his backward, while the intermediate ones seem quite careless in this respect; which seems a part of policy to prevent surprise. As all animals depend most on the ear to apprize them of the approach of danger, the eye taking in only half the horizon at once, and horses possess a great nicety of this sense; as appears from their mode of fighting mentioned No. 8. 5. of this Section, as well as by common observation. There are some parts of a horse, which he cannot conveniently rub, when they itch, as about the shoulder, which he can neither bite with his teeth, nor scratch with his hind foot; when this part itches, he goes to another horse, and gently bites him in the part which he wishes to be bitten, which is immediately done by his intelligent friend. I once observed a young foal thus bite its large mother, who did not choose to drop the grass she had in her mouth, and rubbed her nose against the foal's neck instead of biting it; which evinces that she knew the design of her progeny, and was not governed by a necessary instinct to bite where she was bitten. Many of our shrubs, which would otherwise afford an agreeable food to horses, are armed with thorns or prickles, which secure them from those animals; as the holly, hawthorn, gooseberry, gorse. In the extensive moorlands of Staffordshire, the horses have learnt to stamp upon a gorse-bush with one of their fore-feet for a minute together, and when the points are broken, they eat it without injury. The horses in the new forest in Hampshire are affirmed to do the same by Mr. Gilpin. Forest Scenery, II. 251, and 112. Which is an art other horses in the fertile parts of the country do not possess, and prick their mouths till they bleed, if they are induced by hunger or caprice to attempt eating gorse. Swine have a sense of touch as well as of smell at the end of their nose, which they use as a hand, both to root up the soil, and to turn over and examine objects of food, somewhat like the proboscis of an elephant. As they require shelter from the cold in this climate, they have learnt to collect straw in their mouths to make their nest, when the wind blows cold; and to call their companions by repeated cries to assist in the work, and add to their warmth by their numerous bedfellows. Hence these animals, which are esteemed so unclean, have also learned never to befoul their dens, where they have liberty, with their own excrement; an art, which cows and horses, which have open hovels to run into, have never acquired. I have observed great sagacity in swine; but the short lives we allow them, and their general confinement, prevents their improvement, which might probably be otherwise greater than that of dogs. Instances of the sagacity and knowledge of animals are very numerous to every observer, and their docility in learning various arts from mankind, evinces that they may learn similar arts from their own species, and thus be possessed of much acquired and traditional knowledge. A dog whose natural prey is sheep, is taught by mankind, not only to leave them unmolested, but to guard them; and to hunt, to set, or to destroy other kinds of animals, as birds, or vermin; and in some countries to catch fish, in others to find truffles, and to practise a great variety of tricks; is it more surprising that the crows should teach each other, that the hawk can catch less birds, by the superior swiftness of his wing, and if two of them follow him, till he succeeds in his design, that they can by force share a part of the capture? This I have formerly observed with attention and astonishment. There is one kind of pelican mentioned by Mr. Osbeck, one of Linnæus's travelling pupils (the pelicanus aquilus), whose food is fish; and which it takes from other birds, because it is not formed to catch them itself; hence it is called by the English a Man-of-war-bird, Voyage to China, p. 88. There are many other interesting anecdotes of the pelican and cormorant, collected from authors of the best authority, in a well-managed Natural History for Children, published by Mr. Galton. Johnson. London. And the following narration from the very accurate Mons. Adanson, in his Voyage to Senegal, may gain credit with the reader: as his employment in this country was solely to make observations in natural history. On the river Niger, in his road to the island Griel, he saw a great number of pelicans, or wide throats. "They moved with great state like swans upon the water, and are the largest bird next to the ostrich; the bill of the one I killed was upwards of a foot and half long, and the bag fastened underneath it held two and twenty pints of water. They swim in flocks, and form a large circle, which they contract afterwards, driving the fish before them with their legs: when they see the fish in sufficient number confined in this space, they plunge their bill wide open into the water, and shut it again with great quickness. They thus get fish into their throat-bag, which they eat afterwards on shore at their leisure." P. 247. XII. The knowledge and language of those birds, that frequently change their climate with the seasons, is still more extensive: as they perform these migrations in large societies, and are less subject to the power of man, than the resident tribes of birds. They are said to follow a leader during the day, who is occasionally changed, and to keep a continual cry during the night to keep themselves together. It is probable that these emigrations were at first undertaken as accident directed, by the more adventurous of their species, and learned from one another like the discoveries of mankind in navigation. The following circumstances strongly support this opinion. 1. Nature has provided these animals, in the climates where they are produced, with another resource: when the season becomes too cold for their constitutions, or the food they were supported with ceases to be supplied, I mean that of sleeping. Dormice, snakes, and bats, have not the means of changing their country; the two former from the want of wings, and the latter from his being not able to bear the light of the day. Hence these animals are obliged to make use of this resource, and sleep during the winter. And those swallows that have been hatched too late in the year to acquire their full strength of pinion, or that have been maimed by accident or disease, have been frequently found in the hollows of rocks on the sea coasts, and even under water in this torpid state, from which they have been revived by the warmth of a fire. This torpid state of swallows is testified by innumerable evidences both of antient and modern names. Aristotle speaking of the swallows says, "They pass into warmer climates in winter, if such places are at no great distance; if they are, they bury themselves in the climates where they dwell," (8. Hist. c. 16. See also Derham's Phys. Theol. v. ii. p. 177.) Hence their emigrations cannot depend on a _necessary_ instinct, as the emigrations themselves are not _necessary_. 2. When the weather becomes cold, the swallows in the neighbourhood assemble in large flocks; that is, the unexperienced attend those that have before experienced the journey they are about to undertake: they are then seen some time to hover on the coast, till there is calm whether, or a wind, that suits the direction of their flight. Other birds of passage have been drowned by thousands in the sea, or have settled on ships quite exhausted with fatigue. And others, either by mistaking their course, or by distress of weather, have arrived in countries where they were never seen before: and thus are evidently subject to the same hazards that the human species undergo, in the execution of their artificial purposes. 3. The same birds are emigrant from some countries and not so from others: the swallows were seen at Goree in January by an ingenious philosopher of my acquaintance, and he was told that they continued there all the year; as the warmth of the climate was at all seasons sufficient for their own constitutions, and for the production of the flies that supply them with nourishment. Herodotus says, that in Libya, about the springs of the Nile, the swallows continue all the year. (L. 2.) Quails (tetrao corturnix, Lin.) are birds of passage from the coast of Barbary to Italy, and have frequently settled in large shoals on ships fatigued with their flight. (Ray, Wisdom of God, p. 129. Derham. Physic. Theol. v. ii. p. 178,) Dr. Ruffel, in his History of Aleppo, observes that the swallows visit that country about the end of February, and having hatched their young disappear about the end of July; and returning again about the beginning of October, continue about a fortnight, and then again disappear. (P. 70.) When my late friend Dr. Chambres, of Derby, was on the island of Caprea in the bay of Naples, he was informed that great flights of quails annually settle on that island about the beginning of May, in their passage from Africa to Europe. And that they always come when the south-east wind blows, are fatigued when they rest on this island, and are taken in such amazing quantities and sold to the Continent, that the inhabitants pay the bishop his stipend out of the profits arising from the sale of them. The flights of these birds across the Mediterranean are recorded near three thousand years ago. "There went forth a wind from the Lord and brought quails from the sea, and let them fall upon the camp, a day's journey round about it, and they were two cubits above the earth," (Numbers, chap. ii. ver. 31.) In our country, Mr. Pennant informs us, that some quails migrate, and others only remove from the internal parts of the island to the coasts, (Zoology, octavo, 210.) Some of the ringdoves and stares breed here, others migrate, (ibid. 510, ii.) And the slender billed small birds do not all quit these kingdoms in the winter, though the difficulty of procuring the worms and insects, that they feed on, supplies the same reason for migration to them all, (ibid. 511.) Linnæus has observed, that in Sweden the female chaffinches quit that country in September, migrating into Holland, and leave their mates behind till their return in spring. Hence he has called them Fringilla cælebs, (Amæn. Acad. ii. 42. iv. 595.) Now in our climate both sexes of them are perennial birds. And Mr. Pennant observes that the hoopoe, chatterer, hawfinch, and crossbill, migrate into England so rarely, and at such uncertain times, as not to deserve to be ranked among our birds of passage, (ibid. 511.) The water fowl, as geese and ducks, are better adapted for long migrations, than the other tribes of birds, as, when the weather is calm, they can not only rest themselves, or sleep upon the ocean, but possibly procure some kind of food from it. Hence in Siberia, as soon as the lakes are frozen, the water fowl, which are very numerous, all disappear, and are supposed to fly to warmer climates, except the rail, which, from its inability for long flights, probably sleeps, like our bat, in their winter. The following account from the Journey of Professor Gmelin, may entertain the reader. "In the neighbourhood of Krasnoiark, amongst many other emigrant water fowls, we observed a great number of rails, which when pursued never took flight, but endeavoured to escape by running. We enquired how these birds, that could not fly, could retire into other countries in the winter, and were told, both by the Tartars and Assanians, that they well knew those birds could not alone pass into other countries: but when the cranes (les grues) retire in autumn, each one takes a rail (un rale) upon his back, and carries him to a warmer climate." _Recapitulation._ 1. All birds of passage can exist in the climates, where they are produced. 2. They are subject in their migrations to the same accidents and difficulties, that mankind are subject to in navigation. 3. The same species of birds migrate from some countries, and are resident in others. From all these circumstances it appears that the migrations of birds are not produced by a necessary instinct, but are accidental improvements, like the arts among mankind, taught by their cotemporaries, or delivered by tradition from one generation of them to another. XIII. In that season of the year which supplies the nourishment proper for the expected brood, the birds enter into a contract of marriage, and with joint labour construct a bed for the reception of their offspring. Their choice of the proper season, their contracts of marriage, and the regularity with which they construct their nests, have in all ages excited the admiration of naturalists; and have always been attributed to the power of instinct, which, like the occult qualities of the antient philosophers, prevented all further enquiry. We shall consider them in their order. _Their Choice of the Season._ Our domestic birds, that are plentifully supplied throughout the year with their adapted food, and are covered with houses from the inclemency of the weather, lay their eggs at any season: which evinces that the spring of the year is not pointed out to them by a necessary instinct. Whilst the wild tribes of birds choose this time of the year from their acquired knowledge, that the mild temperature of the air is more convenient for hatching their eggs, and is soon likely to supply that kind of nourishment, that is wanted for their young. If the genial warmth of the spring produced the passion of love, as it expands the foliage of trees, all other animals should feel its influence as well as birds: but, the viviparous creatures, as they suckle their young, that is, as they previously digest the natural food, that it may better suit the tender stomachs of their offspring, experience the influence of this passion at all seasons of the year, as cats and bitches. The graminivorous animals indeed generally produce their young about the time when grass is supplied in the greatest plenty, but this is without any degree of exactness, as appears from our cows, sheep, and hares, and may be a part of the traditional knowledge, which they learn from the example of their parents. _Their Contracts of Marriage._ Their mutual passion, and the acquired knowledge, that their joint labour is necessary to procure sustenance for their numerous family, induces the wild birds to enter into a contract of marriage, which does not however take place among the ducks, geese, and fowls, that are provided with their daily food from our barns. An ingenious philosopher has lately denied, that animals can enter into contracts, and thinks this an essential difference between them and the human creature:--but does not daily observation convince us, that they form contracts of friendship with each other, and with mankind? When puppies and kittens play together, is there not a tacit contract, that they will not hurt each other? And does not your favorite dog expect you should give him his daily food, for his services and attention to you? And thus barters his love for your protection? In the same manner that all contracts are made amongst men, that do not understand each others arbitrary language. _Construction of their Nests._ 1. They seem to be instructed how to build their nests from their observation of that, in which they were educated, and from their knowledge of those things, that are most agreeable to their touch in respect: to warmth, cleanliness, and stability. They choose their situations from their ideas of safety from their enemies, and of shelter from the weather. Nor is the colour of their nests a circumstance unthought of; the finches, that build in green hedges, cover their habitations with green moss; the swallow or martin, that builds against rocks and houses, covers her's with clay, whilst the lark chooses vegetable straw nearly of the colour of the ground she inhabits: by this contrivance, they are all less liable to be discovered by their adversaries. 2. Nor are the nests of the same species of birds constructed always of the same materials, nor in the same form; which is another circumstance that ascertains, that they are led by observation. In the trees before Mr. Levet's house in Lichfield, there are annually nests built by sparrows, a bird which usually builds under the tiles of houses, or the thatch of barns. Not finding such convenient situations for their nests, they build a covered nest bigger than a man's head, with an opening like a mouth at the side, resembling that of a magpie, except that it is built with straw and hay, and lined with feathers, and so nicely managed as to be a defence against both wind and rain. The following extract from a Letter of the Rev. Mr. J. Darwin, of Carleton Scroop in Lincolnshire, authenticates a curious fact of this kind. "When I mentioned to you the circumstance of crows or rooks building in the spire of Welbourn church, you expressed a desire of being well informed of the certainty of the fact. Welbourn is situated in the road from Grantham to Lincoln on the Cliff row; I yesterday took a ride thither, and enquired of the rector, Mr. Ridgehill, whether the report was true, that rooks built in the spire of his church. He assured me it was true, and that they had done so time immemorial, as his parishioners affirmed. There was a common tradition, he said, that formerly a rookery in some high trees adjoined the church yard, which being cut down (probably in the spring, the building season), the rooks removed to the church, and built their nests on the outside of the spire on the tops of windows, which by their projection a little from the spire made them convenient room, but that they built also on the inside. I saw two nests made with sticks on the outside, and in the spires, and Mr. Ridgehill said there were always a great many. "I spent the day with Mr. Wright, a clergyman, at Fulbeck, near Welbourn, and in the afternoon Dr. Ellis of Headenham, about two miles from Welbourn, drank tea at Mr. Wright's, who said he remembered, when Mr. Welby lived at Welbourn, that he received a letter from an acquaintance in the west of England, desiring an answer, whether the report of rooks building in Welbourn church was true, as a wager was depending on that subject; to which he returned an answer ascertaining the fact, and decided the wager." Aug. 30, 1794. So the jackdaw (corvus monedula) generally builds in church-steeples, or under the roofs of high houses; but at Selbourn, in Southamptonshire, where towers and steeples are not sufficiently numerous, these birds build in forsaken rabbit burrows. See a curious account of these subterranean nests in White's History of Selbourn, p. 59. Can the skilful change of architecture in these birds and the sparrows above mentioned be governed by instinct? Then they must have two instincts, one for common, and the other for extraordinary occasions. I have seen green worsted in a nest, which no where exists in nature: and the down of thistles in those nests, that were by some accident constructed later in the summer, which material could not be procured for the earlier nests: in many different climates they cannot procure the same materials, that they use in ours. And it is well known, that the canary birds, that are propagated in this country, and the finches, that are kept tame, will build their nests of any flexile materials, that are given them. Plutarch, in his Book on Rivers, speaking of the Nile, says, "that the swallows collect a material, when the waters recede, with which they form nests, that are impervious to water." And in India there is a swallow that collects a glutinous substance for this purpose, whose nest is esculent, and esteemed a principal rarity amongst epicures, (Lin. Syst. Nat.) Both these must be constructed of very different materials from those used by the swallows of our country. In India the birds exert more artifice in building their nests on account of the monkeys and snakes: some form their pensile nests in the shape of a purse, deep and open at top; others with a hole in the side; and others, still more cautious, with an entrance at the very bottom, forming their lodge near the summit. But the taylor-bird will not ever trust its nest to the extremity of a tender twig, but makes one more advance to safety by fixing it to the leaf itself. It picks up a dead leaf, and sews it to the side of a living one, its slender bill being its needle, and its thread some fine fibres; the lining consists of feathers, gossamer, and down; its eggs are white, the colour of the bird light yellow, its length three inches, its weight three sixteenths of an ounce; so that the materials of the nest, and the weight of the bird, are not likely to draw down an habitation so slightly suspended. A nest of this bird is preserved in the British Museum, (Pennant's Indian Zoology). This calls to one's mind the Mosaic account of the origin of mankind, the first dawning of art there ascribed to them, is that of sewing leaves together. For many other curious kinds of nests see Natural History for Children, by Mr. Galton. Johnson. London. Part I. p. 47. Gen. Oriolus. 3. Those birds that are brought up by our care, and have had little communication with others of their own species, are very defective in this acquired knowledge; they are not only very awkward in the construction of their nests, but generally scatter their eggs in various parts of the room or cage, where they are confined, and seldom produce young ones, till, by failing in their first attempt, they have learnt something from their own observation. 4. During the time of incubation birds are said in general to turn their eggs every day; some cover them, when they leave the nest, as ducks and geese; in some the male is said to bring food to the female, that she may have less occasion of absence, in others he is said to take her place, when she goes in quest of food; and all of them are said to leave their eggs a shorter time in cold weather than in warm. In Senegal the ostrich sits on her eggs only during the night, leaving them in the day to the heat of the sun; but at the Cape of Good Hope, where the heat is less, she sits on them day and night. If it should be asked, what induces a bird to sit weeks on its first eggs unconscious that a brood of young ones will be the product? The answer must be, that it is the same passion that induces the human mother to hold her offspring whole nights and days in her fond arms, and press it to her bosom, unconscious of its future growth to sense and manhood, till observation or tradition have informed her. 5. And as many ladies are too refined to nurse their own children, and deliver them to the care and provision of others; so is there one instance of this vice in the feathered world. The cuckoo in some parts of England, as I am well informed by a very distinct and ingenious gentleman, hatches and educates her own young; whilst in other parts she builds no nest, but uses that of some lesser bird, generally either of the wagtail, or hedge sparrow, and depositing one egg in it, takes no further care of her progeny. As the Rev. Mr. Stafford was walking in Glosop Dale, in the Peak of Derbyshire, he saw a cuckoo rise from its nest. The nest was on the stump of a tree, that had been some time felled, among some chips that were in part turned grey, so as much to resemble the colour of the bird, in this nest were two young cuckoos: tying a string about the leg of one of them, he pegged the other end of it to the ground, and very frequently for many days beheld the old cuckoo feed these her young, as he stood very near them. The following extract of a Letter from the Rev. Mr. Wilmot, of Morley, near Derby, strengthens the truth of the fact above mentioned, of the cuckoo sometimes making a nest, and hatching her own young. "In the beginning of July 1792, I was attending some labourers on my farm, when one of them said to me, "There is a bird's nest upon one of the Coal-slack Hills; the bird is now sitting, and is exactly like a cuckoo. They say that cuckoo's never hatch their own eggs, otherwise I should have sworn it was one." He took me to the spot, it was in an open fallow ground; the bird was upon the nest, I stood and observed her some time, and was perfectly satisfied it was a cuckoo; I then put my hand towards her, and she almost let me touch her before she rose from the nest, which she appeared to quit with great uneasiness, skimming over the ground in the manner that a hen partridge does when disturbed from a new hatched brood, and went only to a thicket about forty or fifty yards from the nest; and continued there as long as I staid to observe her, which was not many minutes. In the nest, which was barely a hole scratched out of the coal-slack in the manner of a plover's nest, I observed three eggs, but did not touch them. As I had labourers constantly at work in that field, I went thither every day, and always looked to see if the bird was there, but did not disturb her for seven or eight days, when I was tempted to drive her from the nest, and found _two_ young ones, that appeared to have been hatched some days, but there was no appearance of the third egg. I then mentioned this extraordinary circumstance (for such I thought it) to Mr. and Mrs. Holyoak of Bidford Grange, Warwickshire, and to Miss M. Willes, who were on a visit at my house, and who all went to see it. Very lately I reminded Mr. Holyoak of it, who told me he had a perfect recollection of the whole, and that, considering it a curiosity, he walked to look at it several times, was perfectly satisfied as to its being a cuckoo, and thought her more attentive to her young, than any other bird he ever observed, having always found her brooding her young. In about a week after I first saw the young ones, one of them was missing, and I rather suspected my plough-boys having taken it; though it might possibly have been taken by a hawk, some time when the old one was seeking food. I never found her off her nest but once, and that was the last time I saw the remaining young one, when it was almost full feathered. I then went from home for two or three days, and, when I returned, the young one was gone, which I take for granted had flown. Though during this time I frequently saw cuckoos in the thicket I mention, I never observed any one, that I supposed to be the cock-bird, paired with this hen." Nor is this a new observation, though it is entirely overlooked by the modern naturalists, for Aristotle speaking of the cuckoo, asserts that she sometimes builds her nest among broken rocks, and on high mountains, (L. 6. H. c. 1.) but adds in another place that she generally possesses the nest of another bird, (L. 6. H. c. 7.) And Niphus says that cuckoos rarely build for themselves, most frequently laying their eggs in the nests of other birds, (Gesner, L. 3. de Cuculo.) The Philosopher who is acquainted with these facts concerning the cuckoo, would seem to have very little _reason_ himself, if he could imagine this neglect of her young to be a necessary _instinct_! XIV. The deep recesses of the ocean are inaccessible to mankind, which prevents us from having much knowledge of the arts and government of its inhabitants. 1. One of the baits used by the fisherman is an animal called an Old Soldier, his size and form are somewhat like the craw-fish, with this difference, that his tail is covered with a tough membrane instead of a shell; and to obviate this defect, he seeks out the uninhabited shell of some dead fish, that is large enough to receive his tail, and carries it about with him as part of his clothing or armour. 2. On the coasts about Scarborough, where the haddocks, cods, and dog-fish, are in great abundance, the fishermen universally believe that the dog-fish make a line, or semicircle, to encompass a shoal of haddocks and cod, confining them within certain limits near the shore, and eating them as occasion requires. For the haddocks and cod are always found near the shore without any dog-fish among them, and the dog-fish further off without any haddocks or cod; and yet the former are known to prey upon the latter, and in some years devour such immense quantities as to render this fishery more expensive than profitable. 3. The remora, when he wishes to remove his situation, as he is a very slow swimmer, is content to take an outside place on whatever conveyance is going his way; nor can the cunning animal be tempted to quit his hold of a ship when she is sailing, not even for the lucre of a piece of pork, lest it should endanger the loss of his passage: at other times he is easily caught with the hook. 4. The crab-fish, like many other testaceous animals, annually changes its shell; it is then in a soft state, covered only with a mucous membrane, and conceals itself in holes in the sand or under weeds; at this place a hard shelled crab always stands centinel, to prevent the sea insects from injuring the other in its defenceless state; and the fishermen from his appearance know where to find the soft ones, which they use for baits in catching other fish. And though the hard shelled crab, when he is on this duty, advances boldly to meet the foe, and will with difficulty quit the field; yet at other times he shews great timidity, and has a wonderful speed in attempting his escape; and, if often interrupted, will pretend death like the spider, and watch an opportunity to sink himself into the sand, keeping only his eyes above. My ingenious friend Mr. Burdett, who favoured me with these accounts at the time he was surveying the coasts, thinks the commerce between the sexes takes place at this time, and inspires the courage of the creature. 5. The shoals of herrings, cods, haddocks, and other fish, which approach our shores at certain seasons, and quit them at other seasons without leaving one behind; and the salmon, that periodically frequent our rivers, evince, that there are vagrant tribes of fish, that perform as regular migrations as the birds of passage already mentioned. 6. There is a cataract on the river Liffey in Ireland about nineteen feet high: here in the salmon season many of the inhabitants amuse themselves in observing these fish leap up the torrent. They dart themselves quite out of the water as they ascend, and frequently fall back many times before they surmount it, and baskets made of twigs are placed near the edge of the stream to catch them in their fall. I have observed, as I have sat by a spout of water, which descends from a stone trough about two feet into a stream below, at particular seasons of the year, a great number of little fish called minums, or pinks, throw themselves about twenty times their own length out of the water, expecting to get into the trough above. This evinces that the storgee, or attention of the dam to provide for the offspring, is strongly exerted amongst the nations of fish, where it would seem to be the most neglected; as these salmon cannot be supposed to attempt so difficult and dangerous a task without being conscious of the purpose or end of their endeavours. It is further remarkable, that most of the old salmon return to the sea before it is proper for the young shoals to attend them, yet that a few old ones continue in the rivers so late, that they become perfectly emaciated by the inconvenience of their situation, and this apparently to guide or to protect the unexperienced brood. Of the smaller water animals we have still less knowledge, who nevertheless probably possess many superior arts; some of these are mentioned in Botanic Garden, P. I. Add. Note XXVII. and XXVIII. The nympha of the water-moths of our rivers, which cover themselves with cases of straw, gravel, and shell, contrive to make their habitations, nearly in equilibrium with the water; when too heavy, they add a bit of wood or straw; when too light, a bit of gravel. Edinb. Trans. All these circumstances bear a near resemblance to the deliberate actions of human reason. XV. We have a very imperfect acquaintance with the various tribes of insects: their occupations, manner of life, and even the number of their senses, differ from our own, and from each other; but there is reason to imagine, that those which possess the sense of touch in the most exquisite degree, and whole occupations require the most constant exertion of their powers, are induced with a greater proportion or knowledge and ingenuity. The spiders of this country manufacture nets of various forms, adapted to various situations, to arrest the flies that are their food; and some of them have a house or lodging-place in the middle of the net, well contrived for warmth, security, or concealment. There is a large spider in South America, who constructs nets of so strong a texture as to entangle small birds, particularly the humming bird. And in Jamaica there is another spider, who digs a hole in the earth obliquely downwards, about three inches in length, and one inch in diameter, this cavity she lines with a tough thick web, which when taken out resembles a leathern purse: but what is most curious, this house has a door with hinges, like the operculum of some sea shells; and herself and family, who tenant this nest, open and shut the door, whenever they pass or repass. This history was told me, and the nest with its operculum shewn me by the late Dr. Butt of Bath, who was some years physician in Jamaica. The production of these nets is indeed a part of the nature or conformation of the animal, and their natural use is to supply the place of wings, when she wishes to remove to another situation. But when she employs them to entangle her prey, there are marks of evident design, for she adapts the form of each net to its situation, and strengthens those lines, that require it, by joining others to the middle of them, and attaching those others to distant objects, with the same individual art, that is used by mankind in supporting the masts and extending the sails of ships. This work is executed with more mathematical exactness and ingenuity by the field spiders, than by those in our houses, as their constructions are more subjected to the injuries of dews and tempests. Besides the ingenuity shewn by these little creatures in taking their prey, the circumstance of their counterfeiting death, when they are put into terror, is truly wonderful; and as soon as the object of terror is removed, they recover and run away. Some beetles are also said to possess this piece of hypocrisy. The curious webs, or chords, constructed by some young caterpillars to defend themselves from cold, or from insects of prey; and by silk-worms and some other caterpillars, when they transmigrate into aureliæ or larvæ, have deservedly excited the admiration of the inquisitive. But our ignorance of their manner of life, and even of the number of their senses, totally precludes us from understanding the means by which they acquire this knowledge. The care of the salmon in choosing a proper situation for her spawn, the structure of the nests of birds, their patient incubation, and the art of the cuckoo in depositing her egg in her neighbour's nursery, are instances of great sagacity in those creatures: and yet they are much inferior to the arts exerted by many of the insect tribes on similar occasions. The hairy excrescences on briars, the oak apples, the blasted leaves of trees, and the lumps on the backs of cows, are situations that are rather produced than chosen by the mother insect for the convenience of her offspring. The cells of bees, wasps, spiders, and of the various coralline insects, equally astonish us, whether we attend to the materials or to the architecture. But the conduct of the ant, and of some species of the ichneumon fly in the incubation of their eggs, is equal to any exertion of human science. The ants many times in a day move their eggs nearer the surface of their habitation, or deeper below it, as the heat of the weather varies; and in colder days lie upon them in heaps for the purpose of incubation: if their mansion is too dry, they carry them to places where there is moisture, and you may distinctly see the little worms move and suck up the water. When too much moisture approaches their nest, they convey their eggs deeper in the earth, or to some other place of safety. (Swammerd. Epil. ad Hist. Insects, p. 153. Phil. Trans. No. 23. Lowthrop. V. 2. p. 7.) There is one species of ichneumon-fly, that digs a hole in the earth, and carrying into it two or three living caterpillars, deposits her eggs, and nicely closing up the nest leaves them there; partly doubtless to assist the incubation, and partly to supply food to her future young, (Derham. B. 4, c. 13. Aristotle Hist. Animal, L. 5. c. 20.) A friend of mine put about fifty large caterpillars collected from cabbages on some bran and a few leaves into a box, and covered it with gauze to prevent their escape. After a few days we saw, from more than three fourths of them, about eight or ten little caterpillars of the ichneumon-fly come out of their backs, and spin each a small cocoon of silk, and in a few days the large caterpillars died. This small fly it seems lays its egg in the back of the cabbage caterpillar, which when hatched preys upon the material, which is produced there for the purpose of making silk for the future nest of the cabbage caterpillar; of which being deprived, the creature wanders about till it dies, and thus our gardens are preserved by the ingenuity of this cruel fly. This curious property of producing a silk thread, which is common to some sea animals, see Botanic Garden, Part I. Note XXVII. and is designed for the purpose of their transformation as in the silk-worm, is used for conveying themselves from higher branches to lower ones of trees by some caterpillars, and to make themselves temporary nests or tents, and by the spider for entangling his prey. Nor is it strange that so much knowledge should be acquired by such small animals; since there is reason to imagine, that these insects have the sense of touch, either in their proboscis, or their antennæ, to a great degree of perfection; and thence may possess, as far as their sphere extends, as accurate knowledge, and as subtle invention, as the discoverers of human arts. XVI. 1. If we were better acquainted with the histories of those insects that are formed into societies, as the bees, wasps, and ants, I make no doubt but we should find, that their arts and improvements are not so similar and uniform as they now appear to us, but that they arose in the same manner from experience and tradition, as the arts of our own species; though their reasoning is from fewer ideas, is busied about fewer objects, and is exerted with less energy. There are some kinds of insects that migrate like the birds before mentioned. The locust of warmer climates has sometimes come over to England; it is shaped like a grasshopper, with very large wings, and a body above an inch in length. It is mentioned as coming into Egypt with an east wind, "The lord brought an east wind upon the land all that day and night, and in the morning the east wind brought the locusts, and covered the face of the earth, so that the land was dark," Exod. x. 13. The migrations of these insects are mentioned in another part of the scripture, "The locusts have no king, yet go they forth all of them in bands," Prov. xxx. 27. The accurate Mr. Adanson, near the river Gambia in Africa, was witness to the migration of these insects. "About eight in the morning, in the month of February, there suddenly arose over our heads a thick cloud, which darkened the air, and deprived us of the rays of the sun. We found it was a cloud of locusts raised about twenty or thirty fathoms from the ground, and covering an extent of several leagues; at length a shower of these insects descended, and after devouring every green herb, while they rested, again resumed their flight. This cloud was brought by a strong east-wind, and was all the morning in passing over the adjacent country." (Voyage to Senegal, 158.) In this country the gnats are sometimes seen to migrate in clouds, like the musketoes of warmer climates, and our swarms of bees frequently travel many miles, and are said in North America always to fly towards the south. The prophet Isaiah has a beautiful allusion to these migrations, "The Lord shall call the fly from the rivers of Egypt, and shall hiss for the bee that is in the land of Assyria," Isa. vii. 18. which has been lately explained by Mr. Bruce, in his travels to discover the source of the Nile. 2. I am well informed that the bees that were carried into Barbadoes, and other western islands, ceased to lay up any honey after the first year, as they found it not useful to them: and are now become very troublesome to the inhabitants of those islands by infesting their sugar houses; but those in Jamaica continue to make honey, as the cold north winds, or rainy seasons of that island, confine them at home for several weeks together. And the bees of Senegal, which differ from those of Europe only in size, make their honey not only superior to ours in delicacy of flavour, but it has this singularity, that it never concretes, but remains liquid as syrup, (Adanson). From some observations of Mr. Wildman, and of other people of veracity, it appears, that during the severe part of the winter season for weeks together the bees are quite benumbed and torpid from the cold, and do not consume any of their provision. This state of sleep, like that of swallows and bats, seems to be the natural resource of those creatures in cold climates, and the making of honey to be an artificial improvement. As the death of our hives of bees appears to be owning to their being kept so warm, as to require food when their stock is exhausted; a very observing gentleman at my request put two hives for many weeks into a dry cellar, and observed, during all that time, they did not consume any of their provision, for their weight did not decrease as it had done when they were kept in the open air. The same observation is made in the Annual Register for 1768, p. 113. And the Rev. Mr. White, in his Method of preserving Bees, adds, that those on the north side of his house consumed less honey in the winter than those on the south side. There is another observation on bees well ascertained, that they at various times, when the season begins to be cold, by a general motion of their legs as they hang in clusters produce a degree of warmth, which is easily perceptible by the hand. Hence by this ingenious exertion, they for a long time prevent the torpid state they would naturally fall into. According to the late observations of Mr. Hunter, it appears that the bee's-wax is not made from the dust of the anthers of flowers, which they bring home on their thighs, but that this makes what is termed bee-bread, and is used for the purpose of feeding the bee-maggots; in the same manner butterflies live on honey, but the previous caterpillar lives on vegetable leaves, while the maggots of large flies require flesh for their food, and those of the ichneumon fly require insects for their food. What induces the bee who lives on honey to lay up vegetable powder for its young? What induces the butterfly to lay its eggs on leaves, when itself feeds on honey? What induces the other flies to seek a food for their progeny different from what they consume themselves? If these are not deductions from their own previous experience or observation, all the actions of mankind must be resolved into instinct. 3. The dormouse consumes but little of its food during the rigour of the season, for they roll themselves up, or sleep, or lie torpid the greatest part of the time; but on warm sunny days experience a short revival, and take a little food, and then relapse into their former state." (Pennant Zoolog. p. 67.) Other animals, that sleep in winter without laying up any provender, are observed to go into their winter beds fat and strong, but return to day-light in the spring season very lean and feeble. The common flies sleep during the winter without any provision for their nourishment, and are daily revived by the warmth of the sun, or of our fires. These whenever they see light endeavour to approach it, having observed, that by its greater vicinity they get free from the degree of torpor, that the cold produces; and are hence induced perpetually to burn themselves in our candles: deceived, like mankind, by the misapplication of their knowledge. Whilst many of the subterraneous insects, as the common worms, seem to retreat so deep into the earth as not to be enlivened or awakened by the difference of our winter days; and stop up their holes with leaves or straws, to prevent the frosts from injuring them, or the centipes from devouring them. The habits of peace, or the stratagems of war, of these subterranean nations are covered from our view; but a friend of mine prevailed on a distressed worm to enter the hole of another worm on a bowling-green, and he presently returned much wounded about his head. And I once saw a worm rise hastily out of the earth into the sunshine, and observed a centipes hanging at its tail: the centipes nimbly quitted the tail, and seizing the worm about its middle cut it in half with its forceps, and preyed upon one part, while the other escaped. Which evinces they have design in stopping the mouths of their habitations. 4. The wasp of this country fixes his habitation under ground, that he may not be affected with the various changes of our climate; but in Jamaica he hangs it on the bough of a tree, where the seasons are less severe. He weaves a very curious paper of vegetable fibres to cover his nest, which is constructed on the same principle with that of the bee, but with a different material; but as his prey consists of flesh, fruits, and insects, which are perishable commodities, he can lay up no provender for the winter. M. de la Loubiere, in his relation of Siam, says, "That in a part of that kingdom, which lies open to great inundations, all the ants make their settlements upon trees; no ants' nests are to be seen any where else." Whereas in our country the ground is their only situation. From the scriptual account of these insects, one might be led to suspect, that in some climates they lay up a provision for the winter. Origen affirms the same, (Cont. Cels. L. 4.) But it is generally believed that in this country they do not, (Prov. vi. 6. xxx. 25.) The white ants of the coast of Africa make themselves pyramids eight or ten feet high, on a base of about the same width, with a smooth surface of rich clay, excessively hard and well built, which appear at a distance like an assemblage of the huts of the negroes, (Adanson). The history of these has been lately well described in the Philosoph. Transactions, under the name of termes, or termites. These differ very much from the nest of our large ant; but the real history of this creature, as well as of the wasp, is yet very imperfectly known. Wasps are said to catch large spiders, and to cut off their legs, and carry their mutilated bodies to their young, Dict. Raison. Tom. I. p. 152. One circumstance I shall relate which fell under my own eye, and shewed the power or reason in a wasp, as it is exercised among men. A wasp, on a gravel walk, had caught a fly nearly as large as himself; kneeling on the ground I observed him separate the tail and the head from the body part, to which the wings were attached. He then took the body part in his paws, and rose about two feet from the ground with it; but a gentle breeze wafting the wings of the fly turned him round in the air, and he settled again with his prey upon the gravel. I then distinctly observed him cut off with his mouth, first one of the wings, and then the other, after which he flew away with it unmolested by the wind. Go, thou sluggard, learn arts and industry from the bee, and from the ant! Go, proud reasoner, and call the worm thy sister! XVII. _Conclusion._ It was before observed how much the superior accuracy of our sense of touch contributes to increase our knowledge; but it is the greater energy and activity of the power of volition (as explained in the former Sections of this work) that marks mankind, and has given him the empire of the world. There is a criterion by which we may distinguish our voluntary acts or thoughts from those that are excited by our sensations: "The former are always employed about the _means_ to acquire pleasureable objects, or to avoid painful ones: while the latter are employed about the _possession_ of those that are already in our power." If we turn our eyes upon the fabric of our fellow animals, we find they are supported with bones, covered with skins, moved by muscles; that they possess the same senses, acknowledge the same appetites, and are nourished by the same aliment with ourselves; and we should hence conclude from the strongest analogy, that their internal faculties were also in some measure similar to our own. Mr. Locke indeed published an opinion, that other animals possessed no abstract or general ideas, and thought this circumstance was the barrier between the brute and the human world. But these abstracted ideas have been since demonstrated by Bishop Berkley, and allowed by Mr. Hume, to have no existence in nature, not even in the mind of their inventor, and we are hence necessitated to look for some other mark of distinction. The ideas and actions of brutes, like those of children, are almost perpetually produced by their present pleasures, or their present pains; and, except in the few instances that have been mentioned in this Section, they seldom busy themselves about the _means_ of procuring future bliss, or of avoiding future misery. Whilst the acquiring of languages, the making of tools, and the labouring for money; which are all only the _means_ of procuring pleasure; and the praying to the Deity, as another _means_ to procure happiness, are characteristic of human nature. * * * * * SECT. XVII. THE CATENATION OF MOTIONS. I. 1. _Catenations of animal motion._ 2. _Are produced by irritations, by sensations, by volitions._ 3. _They continue some time after they have been excited. Cause of catenation._ 4. _We can then exert our attention on other objects._ 5. _Many catenations of motions go on together._ 6. _Some links of the catenations of motions may be left out without disuniting the chain._ 7. _Interrupted circles of motion continue confusedly till they come to the part of the circle, where they were disturbed._ 8. _Weaker catenations are dissevered by stronger._ 9. _Then new catenations take place._ 10. _Much effort prevents their reuniting. Impediment of speech._ 11. _Trains more easily dissevered than circles._ 12. _Sleep destroys volition and external stimulus._ II. _Instances of various catenations in a young lady playing on the harpsichord._ III. 1. _What catenations are the strongest._ 2. _Irritations joined with associations from strongest connexions. Vital motions._ 3. _New links with increased force, cold fits of fever produced._ 4. _New links with decreased force. Cold bath._ 5. _Irritation joined with sensation. Inflammatory fever. Why children cannot tickle themselves. 6. Volition joined with sensation. Irritative ideas of sound become sensible._ 7. _Ideas of imagination, dissevered by irritations, by volition, production of surprise._ I. 1. To investigate with precision the catenations of animal motions, it would be well to attend to the manner of their production; but we cannot begin this disquisition early enough for this purpose, as the catenations of motion seem to begin with life, and are only extinguishable with it; We have spoken of the power of irritation, of sensation, of volition, and of association, as preceding the fibrous motions; we now step forwards, and consider, that conversely they are in their turn preceded by those motions; and that all the successive trains or circles of our actions are composed of this twofold concatenation. Those we shall call trains of action, which continue to proceed without any stated repetitions; and those circles of action, when the parts of them return at certain periods, though the trains, of which they consist, are not exactly similar. The reading an epic poem is a train of actions; the reading a song with a chorus at equal distances in the measure constitutes so many circles of action. 2. Some catenations of animal motion are produced by reiterated successive irritations, as when we learn to repeat the alphabet in its order by frequently reading the letters of it. Thus the vermicular motions of the bowels were originally produced by the successive irritations of the passing aliment; and the succession of actions of the auricles and ventricles of the heart was originally formed by successive stimulus of the blood, these afterwards become part of the diurnal circles of animal actions, as appears by the periodical returns of hunger, and the quickened pulse of weak people in the evening. Other catenations of animal motion are gradually acquired by successive agreeable sensations, as in learning a favourite song or dance; others by disagreeable sensations, as in coughing or nictitation; these become associated by frequent repetition, and afterwards compose parts of greater circles of action like those above mentioned. Other catenations of motions are gradually acquired by frequent voluntary repetitions; as when we deliberately learn to march, read, fence, or any mechanic art, the motions of many of our muscles become gradually linked together in trains, tribes, or circles of action. Thus when any one at first begins to use the tools in turning wood or metals in a lathe, he wills the motions of his hand or fingers, till at length these actions become so connected with the effect, that he seems only to will the point of the chisel. These are caused by volition, connected by association like those above described, and afterwards become parts of our diurnal trains or circles of action. 3. All these catenations of animal motions, are liable to proceed some time after they are excited, unless they are disturbed or impeded by other irritations, sensations, or volitions; and in many instances in spite of our endeavours to stop them; and this property of animal motions is probably the cause of their catenation. Thus when a child revolves some minute on one foot, the spectra of the ambient objects appear to circulate round him some time after he falls upon the ground. Thus the palpitation of the heart continues some time after the object of fear, which occasioned it, is removed. The blush of shame, which is an excess of sensation, and the glow of anger, which is an excess of volition, continue some time, though the affected person finds, that those emotions were caused by mistaken facts, and endeavours to extinguish their appearance. See Sect. XII. 1. 5. 4. When a circle of motions becomes connected, by frequent repetitions as above, we can exert our attention strongly on other objects, and the concatenated circle of motions will nevertheless proceed in due order; as whilst you are thinking on this subject, you use variety of muscles in walking about your parlour, or in sitting at your writing-table. 5. Innumerable catenations of motions may proceed at the same time, without incommoding each other. Of these are the motions of the heart and arteries; those of digestion and glandular secretion; of the ideas, or sensual motions; those of progression, and of speaking; the great annual circle of actions so apparent in birds in their times of breeding and moulting; the monthly circles of many female animals; and the diurnal circles of sleeping and waking, of fulness and inanition. 6. Some links of successive trains or of synchronous tribes of action may be left out without disjoining the whole. Such are our usual trains of recollection; after having travelled through an entertaining country, and viewed many delightful lawns, rolling rivers, and echoing rocks; in the recollection of our journey we leave out the many districts, that we crossed, which were marked with no peculiar pleasure. Such also are our complex ideas, they are catenated tribes of ideas, which do not perfectly resemble their correspondent perceptions, because some of the parts are omitted. 7. If an interrupted circle of actions is not entirely dissevered, it will continue to proceed confusedly, till it comes to the part of the circle, where it was interrupted. The vital motions in a fever from drunkenness, and in other periodical diseases, are instances of this circumstance. The accidental inebriate does not recover himself perfectly till about the same hour on the succeeding day. The accustomed drunkard is disordered, if he has not his usual potation of fermented liquor. So if a considerable part of a connected tribe of action be disturbed, that whole tribe goes on with confusion, till the part of the tribe affected regains its accustomed catenations. So vertigo produces vomiting, and a great secretion of bile, as in sea-sickness, all these being parts of the tribe of irritative catenations. 8. Weaker catenated trains may be dissevered by the sudden exertion of the stronger. When a child first attempts to walk across a room, call to him, and he instantly falls upon the ground. So while I am thinking over the virtues of my friends, if the tea-kettle spurt out some hot water on my stocking; the sudden pain breaks the weaker chain of ideas, and introduces a new group of figures of its own. This circumstance is extended to some unnatural trains of action, which have not been confirmed by long habit; as the hiccough, or an ague-fit, which are frequently curable by surprise. A young lady about eleven years old had for five days had a contraction of one muscle in her fore arm, and another in her arm, which occurred four or five times every minute; the muscles were seen to leap, but without bending the arm. To counteract this new morbid habit, an issue was placed over the convulsed muscle of her arm, and an adhesive plaster wrapped tight like a bandage over the whole fore arm, by which the new motions were immediately destroyed, but the means were continued some weeks to prevent a return. 9. If any circle of actions is dissevered, either by omission of some of the links, as in sleep, or by insertion of other links, as in surprise, new catenations take place in a greater or less degree. The last link of the broken chain of actions becomes connected with the new motion which has broken it, or with that which was nearest the link omitted; and these new catenations proceed instead of the old ones. Hence the periodic returns of ague-fits, and the chimeras of our dreams. 10. If a train of actions is dissevered, much effort of volition or sensation will prevent its being restored. Thus in the common impediment of speech, when the association of the motions of the muscles of enunciation with the idea of the word to be spoken is disordered, the great voluntary efforts, which distort the countenance, prevent the rejoining of the broken associations. See No. II. 10. of this Section. It is thus likewise observable in some inflammations of the bowels, the too strong efforts made by the muscles to carry forwards the offending material fixes it more firmly in its place, and prevents the cure. So in endeavouring to recal to our memory some particular word of a sentence, if we exert ourselves too strongly about it, we are less likely to regain it. 11. Catenated trains or tribes of action are easier dissevered than catenated circles of action. Hence in epileptic fits the synchronous connected tribes of action, which keep the body erect, are dissevered, but the circle of vital motions continues undisturbed. 12. Sleep destroys the power of volition, and precludes the stimuli of external objects, and thence dissevers the trains, of which these are a part; which confirms the other catenations, as those of the vital motions, secretions, and absorptions; and produces the new trains of ideas, which constitute our dreams. II. 1. All the preceding circumstances of the catenations of animal motions will be more clearly understood by the following example of a person learning music; and when we recollect the variety of mechanic arts, which are performed by associated trains of muscular actions catenated with the effects they produce, as in knitting, netting, weaving; and the greater variety of associated trains of ideas caused or catenated by volitions or sensations, as in our hourly modes of reasoning, or imagining, or recollecting, we shall gain some idea of the innumerable catenated trains and circles of action, which form the tenor of our lives, and which began, and will only cease entirely with them. 2. When a young lady begins to learn music, she voluntarily applies herself to the characters of her music-book, and by many repetitions endeavours to catenate them with the proportions of sound, of which they are symbols. The ideas excited by the musical characters are slowly connected with the keys of the harpsichord, and much effort is necessary to produce every note with the proper finger, and in its due place and time; till at length a train of voluntary exertions becomes catenated with certain irritations. As the various notes by frequent repetitions become connected in the order, in which they are produced, a new catenation of sensitive exertions becomes mixed with the voluntary ones above described; and not only the musical symbols of crotchets and quavers, but the auditory notes and tones at the same time, become so many successive or synchronous links in this circle of catenated actions. At length the motions of her fingers become catenated with the musical characters; and these no sooner strike the eye, than the finger presses down the key without any voluntary attention between them; the activity of the hand being connected with the irritation of the figure or place of the musical symbol on the retina; till at length by frequent repetitions of the same tune the movements of her fingers in playing, and the muscles of the larynx in singing, become associated with each other, and form part of those intricate trains and circles of catenated motions, according with the second article of the preceding propositions in No. 1. of this Section. 3. Besides the facility, which by habit attends the execution of this musical performance, a curious circumstance occurs, which is, that when our young musician has began a tune, she finds herself inclined to continue it; and that even when she is carelessly singing alone without attending to her own song; according with the third preceding article. 4. At the same time that our young performer continues to play with great exactness this accustomed tune, she can bend her mind, and that intensely, on some other object, according with the fourth article of the preceding proportions. The manuscript copy of this work was lent to many of my friends at different times for the purpose of gaining their opinions and criticisms on many parts of it, and I found the following anecdote written with a pencil opposite to this page, but am not certain by whom. "I remember seeing the pretty young actress, who succeeded Mrs. Arne in the performance of the celebrated Padlock, rehearse the musical parts at her harpsichord under the eye of her master with great taste and accuracy; though I observed her countenance full of emotion, which I could not account for; at last she suddenly burst into tears; for she had all this time been eyeing a beloved canary bird, suffering great agonies, which at that instant fell dead from its perch." 5. At the same time many other catenated circles of action are going on in the person of our fair musician, as well as the motions of her fingers, such as the vital motions, respiration, the movements of her eyes and eyelids, and of the intricate muscles of vocality, according with the fifth preceding article. 6. If by any strong impression on the mind of our fair musician she should be interrupted for a very inconsiderable time, she can still continue her performance, according to the sixth article. 7. If however this interruption be greater, though the chain of actions be not dissevered, it proceeds confusedly, and our young performer continues indeed to play, but in a hurry without accuracy and elegance, till she begins the tune again, according to the seventh of the preceding articles. 8. But if this interruption be still greater, the circle of actions becomes entirely dissevered, and she finds herself immediately under the necessity to begin over again to recover the lost catenation, according to the eighth preceding article. 9. Or in trying to recover it she will sing some dissonant notes, or strike some improper keys, according to the ninth preceding article. 10. A very remarkable thing attends this breach of catenation, if the performer has forgotten some word of her song, the more energy of mind she uses about it, the more distant is she from regaining it; and artfully employs her mind in part on some other object, or endeavours to dull its perceptions, continuing to repeat, as it were inconsciously, the former part of the song, that she remembers, in hopes to regain the lost connexion. For if the activity of the mind itself be more energetic, or takes its attention more, than the connecting word, which is wanted; it will not perceive the slighter link of this lost word; as who listens to a feeble sound, must be very silent and motionless; so that in this case the very vigour of the mind itself seems to prevent it from regaining the lost catenation, as well as the too great exertion in endeavouring to regain it, according to the tenth preceding article. We frequently experience, when we are doubtful about the spelling of a word, that the greater voluntary exertion we use, that is the more intensely we think about it, the further are we from regaining the lost association between the letters of it, but which readily recurs when we have become careless about it. In the same manner, after having for an hour laboured to recollect the name of some absent person, it shall seem, particularly after sleep, to come into the mind as it were spontaneously; that is the word we are in search of, was joined to the preceding one by association; this association being dissevered, we endeavour to recover it by volition; this very action of the mind strikes our attention more, than the faint link of association, and we find it impossible by this means to retrieve the lost word. After sleep, when volition is entirely suspended, the mind becomes capable of perceiving the fainter link of association, and the word is regained. On this circumstance depends the impediment of speech before mentioned; the first syllable of a word is causable by volition, but the remainder of it is in common conversation introduced by its associations with this first syllable acquired by long habit. Hence when the mind of the stammerer is vehemently employed on some idea of ambition of shining, or fear of not succeeding, the associations of the motions of the muscles of articulation with each other become dissevered by this greater exertion, and he endeavours in vain by voluntary efforts to rejoin the broken association. For this purpose he continues to repeat the first syllable, which is causable by volition, and strives in vain, by various distortions of countenance, to produce the next links, which are subject to association. See Class IV. 3. 1. 1. 11. After our accomplished musician has acquired great variety of tunes and songs, so that some of them begin to cease to be easily recollected, she finds progressive trains of musical notes more frequently forgotten, than those which are composed of reiterated circles, according with the eleventh preceding article. 12. To finish our example with the preceding articles we must at length suppose, that our fair performer falls asleep over her harpsichord; and thus by the suspension of volition, and the exclusion of external stimuli, she dissevers the trains and circles of her musical exertions. III. 1. Many of these circumstances of catenations of motions receive an easy explanation from the four following consequences to the seventh law of animal causation in Sect. IV. These are, first, that those successions or combinations of animal motions, whether they were united by causation, association, or catenation, which have been most frequently repeated, acquire the strongest connection. Secondly, that of these, those, which have been less frequently mixed with other trains or tribes of motion, have the strongest connection. Thirdly, that of these, those, which were first formed, have the strongest connection. Fourthly, that if an animal motion be excited by more than one causation, association, or catenation, at the same time, it will be performed with greater energy. 2. Hence also we understand, why the catenations of irritative motions are more strongly connected than those of the other classes, where the quantity of unmixed repetition has been equal; because they were first formed. Such are those of the secerning and absorbent systems of vessels, where the action of the gland produces a fluid, which stimulates the mouths of its correspondent absorbents. The associated motions seem to be the next most strongly united, from their frequent repetition; and where both these circumstances unite, as in the vital motions, their catenations are indissoluble but by the destruction of the animal. 3. Where a new link has been introduced into a circle of actions by some accidental defect of stimulus; if that defect of stimulus be repeated at the same part of the circle a second or a third time, the defective motions thus produced, both by the repeated defect of stimulus and by their catenation with the parts of the circle of actions, will be performed with less and less energy. Thus if any person is exposed to cold at a certain hour to-day, so long as to render some part of the system for a time torpid; and is again exposed to it at the same hour to-morrow, and the next day; he will be more and more affected by it, till at length a cold fit of fever is completely formed, as happens at the beginning of many of those fevers, which are called nervous or low fevers. Where the patient has slight periodical shiverings and paleness for many days before the febrile paroxysm is completely formed. 4. On the contrary, if the exposure to cold be for so short a time, as not to induce any considerable degree of torpor or quiescence, and is repeated daily as above mentioned, it loses its effect more and more at every repetition, till the constitution can bear it without inconvenience, or indeed without being conscious of it. As in walking into the cold air in frosty weather. The same rule is applicable to increased stimulus, as of heat, or of vinous spirit, within certain limits, as is applied in the two last paragraphs to Deficient Stimulus; as is further explained in Sect. XXXVI. on the Periods of Diseases. 5. Where irritation coincides with sensation to produce the same catenations of motion, as in inflammatory fevers, they are excited with still greater energy than by the irritation alone. So when children expect to be tickled in play, by a feather lightly passed over the lips, or by gently vellicating the soles of their feet, laughter is most vehemently excited; though they can stimulate these parts with their own fingers unmoved. Here the pleasureable idea of playfulness coincides with the vellication; and there is no voluntary exertion used to diminish the sensation, as there would be, if a child should endeavour to tickle himself. See Sect. XXXIV. 1. 4. 6. And lastly, the motions excited by the junction of voluntary exertion with irritation are performed with more energy, than those by irritation singly; as when we listen to small noises, as to the ticking of a watch in the night, we perceive the most weak sounds, that are at other times unheeded. So when we attend to the irritative ideas of sound in our ears, which are generally not attended to, we can hear them; and can see the spectra of objects, which remain in the eye, whenever we please to exert our voluntary power in aid of those weak actions of the retina, or of the auditory nerve. 7. The temporary catenations of ideas, which are caused by the sensations of pleasure or pain, are easily dissevered either by irritations, as when a sudden noise disturbs a day-dream; or by the power of volition, as when we awake from sleep. Hence in our waking hours, whenever an idea occurs, which is incongruous to our former experience, we instantly dissever the train of imagination by the power of volition, and compare the incongruous idea with our previous knowledge of nature, and reject it. This operation of the mind has not yet acquired a specific name, though it is exerted every minute of our waking hours; unless it may be termed INTUITIVE ANALOGY. It is an act of reasoning of which we are unconscious except from its effects in preserving the congruity of our ideas, and bears the same relation to the sensorial power of volition, that irritative ideas, of which we are inconscious except by their effects, do to the sensorial power of irritation; as the former is produced by volition without our attention to it, and the latter by irritation without our attention to them. If on the other hand a train of imagination or of voluntary ideas are excited with great energy, and passing on with great vivacity, and become dissevered by some violent stimulus, as the discharge of a pistol near one's ear, another circumstance takes place, which is termed SURPRISE; which by exciting violent irritation, and violent sensation, employs for a time the whole sensorial energy, and thus dissevers the passing trains of ideas, before the power of volition has time to compare them with the usual phenomena of nature. In this case fear is generally the companion of surprise, and adds to our embarrassment, as every one experiences in some degree when he hears a noise in the dark, which he cannot instantly account for. This catenation of fear with surprise is owing to our perpetual experience of injuries from external bodies in motion, unless we are upon our guard against them. See Sect. XVIII. 17. XIX. 2. Many other examples of the catenations of animal motions are explained in Sect. XXXVI. on the Periods of Diseases. * * * * * SECT. XVIII. OF SLEEP. 1. _Volition is suspended in sleep._ 2. _Sensation continues. Dreams prevent delirium and inflammation._ 3. _Nightmare._ 4. _Ceaseless flow of ideas in dreams._ 5. _We seem to receive them by the senses. Optic nerve perfectly sensible in sleep. Eyes less dazzled after dreaming of visible objects._ 6. _Reverie, belief._ 7. _How we distinguish ideas from perceptions._ 8. _Variety of scenery in dreams, excellence of the sense of vision._ 9. _Novelty of combination in dreams._ 10. _Distinctness of imagery in dreams._ 11. _Rapidity of transaction in dreams._ 12. _Of measuring time. Of dramatic time and place. Why a dull play induces sleep, and an interesting one reverie._ 13. _Consciousness of our existence and identity in dreams._ 14. _How we awake sometimes suddenly, sometimes frequently._ 15. _Irritative motions continue in sleep, internal irritations are succeeded by sensation. Sensibility increases during sleep, and irritability. Morning dreams. Why epilepsies occur in sleep. Ecstacy of children. Case of convulsions in sleep. Cramp, why painful. Asthma. Morning sweats. Increase of heat. Increase of urine in sleep. Why more liable to take cold in sleep. Catarrh from thin night-caps. Why we feel chilly at the approach of sleep, and at waking in the open air._ 16. _Why the gout commences in sleep. Secretions are more copious in sleep, young animals and plants grow more in sleep._ 17. _Inconsistency of dreams. Absence of surprise in dreams._ 18. _Why we forget some dreams and not others._ 19. _Sleep-talkers awake with surprise._ 20. _Remote causes of sleep. Atmosphere with less oxygene. Compression of the brain in spina bifida. By whirling on an horizontal wheel. By cold._ 21. _Definition of sleep._ 1. There are four situations of our system, which in their moderate degrees are not usually termed diseases, and yet abound with many very curious and instructive phenomena; these are sleep, reverie, vertigo, drunkenness. These we shall previously consider, before we step forwards to develop the causes and cures of diseases with the modes of the operation of medicines. As all those trains and tribes of animal motion, which are subjected to volition, were the last that were caused, their connection is weaker than that of the other classes; and there is a peculiar circumstance attending this causation, which is, that it is entirely suspended during sleep; whilst the other classes of motion, which are more immediately necessary to life, as those caused by internal stimuli, for instance the pulsations of the heart and arteries, or those catenated with pleasurable sensation, as the powers of digestion, continue to strengthen their habits without interruption. Thus though man in his sleeping state is a much less perfect animal, than in his waking hours; and though he consumes more than one third of his life in this his irrational situation; yet is the wisdom of the Author of nature manifest even in this seeming imperfection of his work! The truth of this assertion with respect to the large muscles of the body, which are concerned in locomotion, is evident; as no one in perfect sanity walks about in his sleep, or performs any domestic offices: and in respect to the mind, we never exercise our reason or recollection in dreams; we may sometimes seem distracted between contending passions, but we never compare their objects, or deliberate about the acquisition of those objects, if our sleep is perfect. And though many synchronous tribes or successive trains of ideas may represent the houses or walks, which have real existence, yet are they here introduced by their connection with our sensations, and are in truth ideas of imagination, not of recollection. 2. For our sensations of pleasure and pain are experienced with great vivacity in our dreams; and hence all that motley group of ideas, which are caused by them, called the ideas of imagination, with their various associated trains, are in a very vivid manner acted over in the sensorium; and these sometimes call into action the larger muscles, which have been much associated with them; as appears from the muttering sentences, which some people utter in their dreams, and from the obscure barking of sleeping dogs, and the motions of their feet and nostrils. This perpetual flow of the trains of ideas, which constitute our dreams, and which are caused by painful or pleasurable sensation, might at first view be conceived to be an useless expenditure of sensorial power. But it has been shewn, that those motions, which are perpetually excited, as those of the arterial system by the stimulus of the blood, are attended by a great accumulation of sensorial power, after they have been for a time suspended; as the hot-fit of fever is the consequence of the cold one. Now as these trains of ideas caused by sensation are perpetually excited during our waking hours, if they were to be suspended in sleep like the voluntary motions, (which are exerted only by intervals during our waking hours,) an accumulation of sensorial power would follow; and on our awaking a delirium would supervene, since these ideas caused by sensation would be produced with such energy, that we should mistake the trains of imagination for ideas excited by irritation; as perpetually happens to people debilitated by fevers on their first awaking; for in these fevers with debility the general quantity of irritation being diminished, that of sensation is increased. In like manner if the actions of the stomach, intestines, and various glands, which are perhaps in part at least caused by or catenated with agreeable sensation, and which perpetually exist during our waking hours, were like the voluntary motions suspended in our sleep; the great accumulation of sensorial power, which would necessarily follow, would be liable to excite inflammation in them. 3. When by our continued posture in sleep, some uneasy sensations are produced, we either gradually awake by the exertion of volition, or the muscles connected by habit with such sensations alter the position of the body; but where the sleep is uncommonly profound, and those uneasy sensations great, the disease called the incubus, or nightmare, is produced. Here the desire of moving the body is painfully exerted, by the power of moving it, or volition, is incapable of action, till we awake. Many less disagreeable struggles in our dreams, as when we wish in vain to fly from terrifying objects, constitute a slighter degree of this disease. In awaking from the nightmare I have more than once observed, that there was no disorder in my pulse; nor do I believe the respiration is laborious, as some have affirmed. It occurs to people whose sleep is too profound, and some disagreeable sensation exists, which at other times would have awakened them, and have thence prevented the disease of nightmare; as after great fatigue or hunger with too large a supper and wine, which occasion our sleep to be uncommonly profound. See No. 14, of this Section. 4. As the larger muscles of the body are much more frequently excited by volition than by sensation, they are but seldom brought into action in our sleep: but the ideas of the mind are by habit much more frequently connected with sensation than with volition; and hence the ceaseless flow of our ideas in dreams. Every one's experience will teach him this truth, for we all daily exert much voluntary muscular motion: but few of mankind can bear the fatigue of much voluntary thinking. 5. A very curious circumstance attending these our sleeping imaginations is, that we seem to receive them by the senses. The muscles, which are subservient to the external organs of sense, are connected with volition, and cease to act in sleep; hence the eyelids are closed, and the tympanum of the ear relaxed; and it is probable a similarity of voluntary exertion may be necessary for the perceptions of the other nerves of sense; for it is observed that the papillæ of the tongue can be seen to become erected, when we attempt to taste any thing extremely grateful. Hewson Exper. Enquir. V. 2. 186. Albini Annot. Acad. L. i. c. 15. Add to this, that the immediate organs of sense have no objects to excite them in the darkness and silence of the night, but their nerves of sense nevertheless continue to possess their perfect activity subservient to all their numerous sensitive connections. This vivacity of our nerves of sense during the time of sleep is evinced by a circumstance, which almost every one must at some time or other have experienced; that is, if we sleep in the daylight, and endeavour to see some object in our dream, the light is exceedingly painful to our eyes; and after repeated struggles we lament in our sleep, that we cannot see it. In this case I apprehend the eyelid is in some degree opened by the vehemence of our sensations; and, the iris being dilated, the optic nerve shews as great or greater sensibility than in our waking hours. See No. 15. of this Section. When we are forcibly waked at midnight from profound sleep, our eyes are much dazzled with the light of the candle for a minute or two, after there has been sufficient time allowed for the contraction of the iris; which is owing to the accumulation of sensorial power in the organ of vision during its state of less activity. But when we have dreamt much of visible objects, this accumulation of sensorial power in the organ of vision is lessened or prevented, and we awake in the morning without being dazzled with the light, after the iris has had time to contract itself. This is a matter of great curiosity, and may be thus tried by any one in the day-light. Close your eyes, and cover them with your hat; think for a minute on a tune, which you are accustomed to, and endeavour to sing it with as little activity of mind as possible. Suddenly uncover and open your eyes, and in one second of time the iris will contract itself, but you will perceive the day more luminous for several seconds, owing to the accumulation of sensorial power in the optic nerve. Then again close and cover your eyes, and think intensely on a cube of ivory two inches diameter, attending first to the north and south sides of it, and then to the other four sides of it; then get a clear image in your mind's eye of all the sides of the same cube coloured red; and then of it coloured green; and then of it coloured blue; lastly, open your eyes as in the former experiment, and after the first second of time allowed for the contraction of the iris, you will not perceive any increase of the light of the day, or dazzling; because now there is no accumulation of sensorial power in the optic nerve; that having been expended by its action in thinking over visible objects. This experiment is not easy to be made at first, but by a few patient trials the fact appears very certain; and shews clearly, that our ideas of imagination are repetitions of the motions of the nerve, which were originally occasioned by the stimulus of external bodies; because they equally expend the sensorial power in the organ of sense. See Sect. III. 4. which is analogous to our being as much fatigued by thinking as by labour. 6. Nor is it in our dreams alone, but even in our waking reveries, and in great efforts of invention, so great is the vivacity of our ideas, that we do not for a time distinguish them from the real presence of substantial objects; though the external organs of sense are open, and surrounded with their usual stimuli. Thus whilst I am thinking over the beautiful valley, through which I yesterday travelled, I do not perceive the furniture of my room: and there are some, whose waking imaginations are so apt to run into perfect reverie, that in their common attention to a favourite idea they do not hear the voice of the companion, who accosts them, unless it is repeated with unusual energy. This perpetual mistake in dreams and reveries, where our ideas of imagination are attended with a belief of the presence of external objects, evinces beyond a doubt, that all our ideas are repetitions of the motions of the nerves of sense, by which they were acquired; and that this belief is not, as some late philosophers contend, an instinct necessarily connected only with our perceptions. 7. A curious question demands our attention in this place; as we do not distinguish in our dreams and reveries between our perceptions of external objects, and our ideas of them in their absence, how do we distinguish them at any time? In a dream, if the sweetness of sugar occurs to my imagination, the whiteness and hardness of it, which were ideas usually connected with the sweetness, immediately follow in the train; and I believe a material lump of sugar present before my senses: but in my waking hours, if the sweetness occurs to my imagination, the stimulus of the table to my hand, or of the window to my eye, prevents the other ideas of the hardness and whiteness of the sugar from succeeding; and hence I perceive the fallacy, and disbelieve the existence of objects correspondent to those ideas, whose tribes or trains are broken by the stimulus of other objects. And further in our waking hours, we frequently exert our volition in comparing present appearances with such, as we have usually observed; and thus correct the errors of one sense by our general knowledge of nature by intuitive analogy. See Sect. XVII. 3. 7. Whereas in dreams the power of volition is suspended, we can recollect and compare our present ideas with none of our acquired knowledge, and are hence incapable of observing any absurdities in them. By this criterion we distinguish our waking from our sleeping hours, we can voluntarily recollect our sleeping ideas, when we are awake, and compare them with our waking ones; but we cannot in our sleep _voluntarily_ recollect our waking ideas at all. 8. The vast variety of scenery, novelty of combination, and distinctness of imagery, are other curious circumstances of our sleeping imaginations. The variety of scenery seems to arise from the superior activity and excellence of our sense of vision; which in an instant unfolds to the mind extensive fields of pleasurable ideas; while the other senses collect their objects slowly, and with little combination; add to this, that the ideas, which this organ presents us with, are more frequently connected with our sensation than those of any other. 9. The great novelty of combination is owing to another circumstance; the trains of ideas, which are carried on in our waking thoughts, are in our dreams dissevered in a thousand places by the suspension of volition, and the absence of irritative ideas, and are hence perpetually falling into new catenations. As explained in Sect. XVII. 1. 9. For the power of volition is perpetually exerted during our waking hours in comparing our passing trains of ideas with our acquired knowledge of nature, and thus forms many intermediate links in their catenation. And the irritative ideas excited by the stimulus of the objects, with which we are surrounded, are every moment intruded upon us, and form other links of our unceasing catenations of ideas. 10. The absence of the stimuli of external bodies, and of volition, in our dreams renders the organs of sense liable to be more strongly affected by the powers of sensation, and of association. For our desires or aversions, or the obtrusions of surrounding bodies, dissever the sensitive and associate tribes of ideas in our waking hours by introducing those of irritation and volition amongst them. Hence proceeds the superior distinctness of pleasurable or painful imagery in our sleep; for we recal the figure and the features of a long lost friend, whom we loved, in our dreams with much more accuracy and vivacity than in our waking thoughts. This circumstance contributes to prove, that our ideas of imagination are reiterations of those motions of our organs of sense, which were excited by external objects; because while we are exposed to the stimuli of present objects, our ideas of absent objects cannot be so distinctly formed. 11. The rapidity of the succession of transactions in our dreams is almost inconceivable; insomuch that, when we are accidentally awakened by the jarring of a door, which is opened into our bed-chamber, we sometimes dream a whole history of thieves or fire in the very instant of awaking. During the suspension of volition we cannot compare our other ideas with those of the parts of time in which they exist; that is, we cannot compare the imaginary scene, which is before us, with those changes of it, which precede or follow it: because this act of comparing requires recollection or voluntary exertion. Whereas in our waking hours, we are perpetually making this comparison, and by that means our waking ideas are kept confident with each other by intuitive analogy; but this companion retards the succession of them, by occasioning their repetition. Add to this, that the transactions of our dreams consist chiefly of visible ideas, and that a whole history of thieves and fire may be _beheld_ in an instant of time like the figures in a picture. 12. From this incapacity of attending to the parts of time in our dreams, arises our ignorance of the length of the night; which, but from our constant experience to the contrary, we should conclude was but a few minutes, when our sleep is perfect. The same happens in our reveries; thus when we are possessed with vehement joy, grief, or anger, time appears short, for we exert no volition to compare the present scenery with the past or future; but when we are compelled to perform those exercises of mind or body, which, are unmixed with passion, as in travelling over a dreary country, time appears long; for our desire to finish our journey occasions us more frequently to compare our present situation with the parts of time or place, which are before and behind us. So when we are enveloped in deep contemplation of any kind, or in reverie, as in reading a very interesting play or romance, we measure time very inaccurately; and hence, if a play greatly affects our passions, the absurdities of passing over many days or years, and or perpetual changes of place, are not perceived by the audience; as is experienced by every one, who reads or sees some plays of the immortal Shakespear; but it is necessary for inferior authors to observe those rules of the [Greek: pithanon] and [Greek: prepon] inculcated by Aristotle, because their works do not interest the passions sufficiently to produce complete reverie. Those works, however, whether a romance or a sermon, which do not interest us so much as to induce reverie, may nevertheless incline us to sleep. For those pleasurable ideas, which are presented to us, and are too gentle to excite laughter, (which is attended with interrupted voluntary exertions, as explained Sect. XXXIV. 1. 4.) and which are not accompanied with any other emotion, which usually excites some voluntary exertion, as anger, or fear, are liable to produce sleep; which consists in a suspension of all voluntary power. But if the ideas thus presented to us, and interest our attention, are accompanied with so much pleasurable or painful sensation as to excite our voluntary exertion at the same time, reverie is the consequence. Hence an interesting play produces reverie, a tedious one produces sleep: in the latter we become exhausted by attention, and are not excited to any voluntary exertion, and therefore sleep; in the former we are excited by some emotion, which prevents by its pain the suspension of volition, and in as much as it interests us, induces reverie, as explained in the next Section. But when our sleep is imperfect, as when we have determined to rise in half an hour, time appears longer to us than in most other situations. Here our solicitude not to oversleep the determined time induces us in this imperfect sleep to compare the quick changes of imagined scenery with the parts of time or place, they would have taken up, had they real exigence; and that more frequently than in our waking hours; and hence the time appears longer to us: and I make no doubt, but the permitted time appears long to a man going to the gallows, as the fear of its quick lapse will make him think frequently about it. 13. As we gain our knowledge of time by comparing the present scenery with the past and future, and of place by comparing the situations of objects with each other; so we gain our idea of consciousness by comparing ourselves with the scenery around us; and of identity by comparing our present consciousness with our past consciousness: as we never think of time or place, but when we make the companions above mentioned, so we never think of consciousness, but when we compare our own existence with that of other objects; nor of identity, but when we compare our present and our past consciousness. Hence the consciousness of our own existence, and of our identity, is owing to a voluntary exertion of our minds: and on that account in our complete dreams we neither measure time, are surprised at the sudden changes of place, nor attend to our own existence, or identity; because our power of volition is suspended. But all these circumstances are more or less observable in our incomplete ones; for then we attend a little to the lapse of time, and the changes of place, and to our own existence; and even to our identity of person; for a lady seldom dreams, that she is a soldier; nor a man, that he is brought to bed. 14. As long as our sensations only excite their sensual motions, or ideas, our sleep continues sound; but as soon as they excite desires or aversions, our sleep becomes imperfect; and when that desire or aversion is so strong, as to produce voluntary motions, we begin to awake; the larger muscles of the body are brought into action to remove that irritation or sensation, which a continued posture has caused; we stretch our limbs, and yawn, and our sleep is thus broken by the accumulation of voluntary power. Sometimes it happens, that the act of waking is suddenly produced, and this soon after the commencement of sleep; which is occasioned by some sensation so disagreeable, as instantaneously to excite the power of volition; and a temporary action of all the voluntary motions suddenly succeeds, and we start awake. This is sometimes accompanied with loud noise in the ears, and with some degree of fear; and when it is in great excess, so as to produce continued convulsive motions of those muscles, which are generally subservient to volition, it becomes epilepsy: the fits of which in some patients generally commence during sleep. This differs from the night-mare described in No. 3. of this Section, because in that the disagreeable sensation is not so great as to excite the power of volition into action; for as soon as that happens, the disease ceases. Another circumstance, which sometimes awakes people soon after the commencement of their sleep, is where the voluntary power is already so great in quantity as almost to prevent them from falling asleep, and then a little accumulation of it soon again awakens them; this happens in cases of insanity, or where the mind has been lately much agitated by fear or anger. There is another circumstance in which sleep is likewise of short duration, which arises from great debility, as after great over-fatigue, and in some fevers, where the strength of the patient is greatly diminished, as in these cases the pulse intermits or flutters, and the respiration is previously affected, it seems to originate from the want of some voluntary efforts to facilitate respiration, as when we are awake. And is further treated of in Vol. II. Class I. 2. 1. 2. on the Diseases of the Voluntary Power. Art. Somnus interruptus. 15. We come now to those motions which depend on irritation. The motions of the arterial and glandular systems continue in our sleep, proceeding slower indeed, but stronger and more uniformly, than in our waking hours, when they are incommoded by external stimuli, or by the movements of volition; the motions of the muscles subservient to respiration continue to be stimulated into action, and the other internal senses of hunger, thirst, and lust, are not only occasionally excited in our sleep, but their irritative motions are succeeded by their usual sensations, and make a part of the farrago of our dreams. These sensations of the want of air, of hunger, thirst, and lust, in our dreams, contribute to prove, that the nerves of the external senses are also alive and excitable in our sleep; but as the stimuli of external objects are either excluded from them by the darkness and silence of the night, or their access to them is prevented by the suspension of volition, these nerves of sense fall more readily into their connexions with sensation and with association; because much sensorial power, which during the day was expended in moving the external organs of sense in consequence of irritation from external stimuli, or in consequence of volition, becomes now in some degree accumulated, and renders the internal or immediate organs of sense more easily excitable by the other sensorial powers. Thus in respect to the eye, the irritation from external stimuli, and the power of volition during our waking hours, elevate the eye-lids, adapt the aperture of the iris to the quantity of light, the focus of the crystalline humour, and the angle of the optic axises to the distance of the object, all which perpetual activity during the day expends much sensorial power, which is saved during our sleep. Hence it appears, that not only those parts of the system, which are always excited by internal stimuli, as the stomach, intestinal canal, bile-ducts, and the various glands, but the organs of sense also may be more violently excited into action by the irritation from internal stimuli, or by sensation, during our sleep than in our waking hours; because during the suspension of volition, there is a greater quantity of the spirit of animation to be expended by the other sensorial powers. On this account our irritability to internal stimuli, and our sensibility to pain or pleasure, is not only greater in sleep, but increases as our sleep is prolonged. Whence digestion and secretion are performed better in sleep, than in our waking hours, and our dreams in the morning have greater variety and vivacity, as our sensibility increases, than at night when we first lie down. And hence epileptic fits, which are always occasioned by some disagreeable sensation, so frequently attack those, who are subject to them, in their sleep; because at this time the system is more excitable by painful sensation in consequence of internal stimuli; and the power of volition is then suddenly exerted to relieve this pain, as explained Sect. XXXIV. 1. 4. There is a disease, which frequently affects children in the cradle, which is termed ecstasy, and seems to consist in certain exertions to relieve painful sensation, in which the voluntary power is not so far excited as totally to awaken them, and yet is sufficient to remove the disagreeable sensation, which excites it; in this case changing the posture of the child frequently relieves it. I have at this time under my care an elegant young man about twenty-two years of age, who seldom sleeps more than an hour without experiencing a convulsion fit; which ceases in about half a minute without any subsequent stupor. Large doses of opium only prevented the paroxysms, so long as they prevented him from sleeping by the intoxication, which they induced. Other medicines had no effect on him. He was gently awakened every half hour for one night, but without good effect, as he soon slept again, and the fit returned at about the same periods of time, for the accumulated sensorial power, which occasioned the increased sensibility to pain, was not thus exhausted. This case evinces, that the sensibility of the system to internal excitation increases, as our sleep is prolonged; till the pain thus occasioned produces voluntary exertion; which, when it is in its usual degree, only awakens us; but when it is more violent, it occasions convulsions. The cramp in the calf of the leg is another kind of convulsion, which generally commences in sleep, occasioned by the continual increase of irritability from internal stimuli, or of sensibility, during that state of our existence. The cramp is a violent exertion to relieve pain, generally either of the skin from cold, or of the bowels, as in some diarrhoeas, or from the muscles having been previously overstretched, as in walking up or down steep hills. But in these convulsions of the muscles, which form the calf of the leg, the contraction is so violent as to occasion another pain in consequence of their own too violent contraction; as soon as the original pain, which caused the contraction, is removed. And hence the cramp, or spasm, of these muscles is continued without intermission by this new pain, unlike the alternate convulsions and remissions in epileptic fits. The reason, that the contraction of these muscles of the calf of the leg is more violent during their convulsion than that of others, depends on the weakness of their antagonist muscles; for after these have been contracted in their usual action, as at every step in walking, they are again extended, not, as most other muscles are, by their antagonists, but by the weight of the whole body on the balls of the toes; and that weight applied to great mechanical advantage on the heel, that is, on the other end of the bone of the foot, which thus acts as a lever. Another disease, the periods of which generally commence during our sleep, is the asthma. Whatever may be the remote cause of paroxysms of asthma, the immediate cause of the convulsive respiration, whether in the common asthma, or in what is termed the convulsive asthma, which are perhaps only different degrees of the same disease, must be owing to violent voluntary exertions to relieve pain, as in other convulsions; and the increase of irritability to internal stimuli, or of sensibility, during sleep must occasion them to commence at this time. Debilitated people, who have been unfortunately accustomed to great ingurgitation of spirituous potation, frequently part with a great quantity of water during the night, but with not more than usual in the day-time. This is owing to a beginning torpor of the absorbent system, and precedes anasarca, which commences in the day, but is cured in the night by the increase of the irritability of the absorbent system during sleep, which thus imbibes from the cellular membrane the fluids, which had been accumulated there during the day; though it is possible the horizontal position of the body may contribute something to this purpose, and also the greater irritability of some branches of the absorbent vessels, which open their mouths in the cells of the cellular membrane, than that of other branches. As soon as a person begins to sleep, the irritability and sensibility of the system begins to increase, owing to the suspension of volition and the exclusion of external stimuli. Hence the actions of the vessels in obedience to internal stimulation become stronger and more energetic, though less frequent in respect to number. And as many of the secretions are increased, so the heat of the system is gradually increased, and the extremities of feeble people, which had been cold during the day, become warm. Till towards morning many people become so warm, as to find it necessary to throw off some of their bed-clothes, as soon as they awake; and in others sweats are so liable to occur towards morning during their sleep. Thus those, who are not accustomed to sleep in the open air, are very liable to take cold, if they happen to fall asleep on a garden bench, or in a carriage with the window open. For as the system is warmer during sleep, as above explained, if a current of cold air affects any part of the body, a torpor of that part is more effectually produced, as when a cold blast of air through a key-hole or casement falls upon a person in a warm room. In those cases the affected part possesses less irritability in respect to heat, from its having previously been exposed to a greater stimulus of heat, as in the warm room, or during sleep; and hence, when the stimulus of heat is diminished, a torpor is liable to ensue; that is, we take cold. Hence people who sleep in the open air, generally feel chilly both at the approach of sleep, and on their awaking; and hence many people are perpetually subject to catarrhs if they sleep in a less warm head-dress, than that which they wear in the day. 16. Not only the sensorial powers of irritation and of sensation, but that of association also appear to act with greater vigour during the suspension of volition in sleep. It will be shewn in another place, that the gout generally first attacks the liver, and that afterwards an inflammation of the ball of the great toe commences by association, and that of the liver ceases. Now as this change or metastasis of the activity of the system generally commences in sleep, it follows, that these associations of motion exist with greater energy at that time; that is, that the sensorial faculty of association, like those of irritation and of sensation, becomes in some measure accumulated during the suspension of volition. Other associate tribes and trains of motions, as well as the irritative and sensitive ones, appear to be increased in their activity during the suspension of volition in sleep. As those which contribute to circulate the blood, and to perform the various secretions; as well as the associate tribes and trains of ideas, which contribute to furnish the perpetual dreams of our dreaming imaginations. In sleep the secretions have generally been supposed to be diminished, as the expectorated mucus in coughs, the fluids discharged in diarrhoeas, and in salivation, except indeed the secretion of sweat, which is often visibly increased. This error seems to have arisen from attention to the excretions rather than to the secretions. For the secretions, except that of sweat, are generally received into reservoirs, as the urine into the bladder, and the mucus of the intestines and lungs into their respective cavities; but these reservoirs do not exclude these fluids immediately by their stimulus, but require at the same time some voluntary efforts, and therefore permit them to remain during sleep. And as they thus continue longer in those receptacles in our sleeping hours, a greater part is absorbed from them, and the remainder becomes thicker, and sometimes in less quantity, though at the time it was secreted the fluid was in greater quantity than in our waking hours. Thus the urine is higher coloured after long sleep; which shews that a greater quantity has been secreted, and that more of the aqueous and saline part has been reabsorbed, and the earthy part left in the bladder; hence thick urine in fevers shews only a greater action of the vessels which secrete it in the kidneys, and of those which absorb it from the bladder. The same happens to the mucus expectorated in coughs, which is thus thickened by absorption of its aqueous and saline parts; and the same of the feces of the intestines. From hence it appears, and from what has been said in No. 15. of this Section concerning the increase of irritability and of sensibility during sleep, that the secretions are in general rather increased than diminished during these hours of our existence; and it is probable that nutrition is almost entirely performed in sleep; and that young animals grow more at this time than in their waking hours, as young plants have long since been observed to grow more in the night, which is their time of sleep. 17. Two other remarkable circumstances of our dreaming ideas are their inconsistency, and the total absence of surprise. Thus we seem to be present at more extraordinary metamorphoses of animals or trees, than are to be met with in the fables of antiquity; and appear to be transported from place to place, which seas divide, as quickly as the changes of scenery are performed in a play-house; and yet are not sensible of their inconsistency, nor in the least degree affected with surprise. We must consider this circumstance more minutely. In our waking trains of ideas, those that are inconsistent with the usual order of nature, so rarely have occurred to us, that their connexion is the slightest of all others: hence, when a consistent train of ideas is exhausted, we attend to the external stimuli, that usually surround us, rather than to any inconsistent idea, which might otherwise present itself; and if an inconsistent idea should intrude itself, we immediately compare it with the preceding one, and voluntarily reject the train it would introduce; this appears further in the Section on Reverie, in which state of the mind external stimuli are not attended to, and yet the streams of ideas are kept consistent by the efforts of volition. But as our faculty of volition is suspended, and all external stimuli are excluded in sleep, this slighter connexion of ideas takes place; and the train is said to be inconsistent; that is, dissimilar to the usual order of nature. But, when any consistent train of sensitive or voluntary ideas is flowing along, if any external stimulus affects us so violently, as to intrude irritative ideas forcibly into the mind, it disunites the former train of ideas, and we are affected with surprise. These stimuli of unusual energy or novelty not only disunite our common trains of ideas, but the trains of muscular motions also, which have not been long established by habit, and disturb those that have. Some people become motionless by great surprise, the fits of hiccup and or ague have been often removed by it, and it even affects the movements of the heart, and arteries; but in our sleep, all external stimuli are excluded, and in consequence no surprise can exist. See Section XVII. 3. 7. 18. We frequently awake with pleasure from a dream, which has delighted us, without being able to recollect the transactions of it; unless perhaps at a distance of time, some analogous idea may introduce afresh this forgotten train: and in our waking reveries we sometimes in a moment lose the train of thought, but continue to feel the glow of pleasure, or the depression of spirits, it occasioned: whilst at other times we can retrace with ease these histories of our reveries and dreams. The above explanation of surprise throws light upon this subject. When we are suddenly awaked by any violent stimulus, the surprise totally disunites the trains of our sleeping ideas from these of our waking ones; but if we gradually awake, this does not happen; and we readily unravel the preceding trains of imagination. 19. There are various degrees of surprise; the more intent we are upon the train of ideas, which we are employed about, the more violent must be the stimulus that interrupts them, and the greater is the degree of surprise. I have observed dogs, who have slept by the fire, and by their obscure barking and struggling have appeared very intent on their prey, that shewed great surprise for a few seconds after their awaking by looking eagerly around them; which they did not do at other times of waking. And an intelligent friend of mine has remarked, that his lady, who frequently speaks much and articulately in her sleep, could never recollect her dreams in the morning, when this happened to her: but that when she did not speak in her sleep, she could always recollect them. Hence, when our sensations act so strongly in sleep as to influence the larger muscles, as in those, who talk or struggle in their dreams; or in those, who are affected with complete reverie (as described in the next Section), great surprise is produced, when they awake; and these as well as those, who are completely drunk or delirious, totally forget afterwards their imaginations at those times. 20. As the immediate cause of sleep consists in the suspension of volition, it follows, that whatever diminishes the general quantity of sensorial power, or derives it from the faculty of volition, will constitute a remote cause of sleep; such as fatigue from muscular or mental exertion, which diminishes the general quantity of sensorial power; or an increase of the sensitive motions, as by attending to soft music, which diverts the sensorial power from the faculty of volition; or lastly, by increase of the irritative motions, as by wine, or food; or warmth; which not only by their expenditure of sensorial power diminish the quantity of volition; but also by their producing pleasureable sensations (which occasion other muscular or sensual motions in consequence), doubly decrease the voluntary power, and thus more forcibly produce sleep. See Sect. XXXIV. 1. 4. Another method of inducing sleep is delivered in a very ingenious work lately published by Dr. Beddoes. Who, after lamenting that opium frequently occasions restlessness, thinks, "that in most cases it would be better to induce sleep by the abstraction of stimuli, than by exhausting the excitability;" and adds, "upon this principle we could not have a better soporific than an atmosphere with a diminished proportion of oxygene air, and that common air might be admitted after the patient was asleep." (Observ. on Calculus, &c. by Dr. Beddoes, Murray.) If it should be found to be true, that the excitability of the system depends on the quantity of oxygene absorbed by the lungs in respiration according to the theory of Dr. Beddoes, and of M. Girtanner, this idea of sleeping in an atmosphere with less oxygene in its composition might be of great service in epileptic cases, and in cramp, and even in fits of the asthma, where their periods commence from the increase of irritability during sleep. Sleep is likewise said to be induced by mechanic pressure on the brain in the cases of spina bifida. Where there has been a defect of one of the vertebræ of the back, a tumour is protruded in consequence; and, whenever this tumour has been compressed by the hand, sleep is said to be induced, because the whole of the brain both within the head and spine becomes compressed by the retrocession of the fluid within the tumour. But by what means a compression of the brain induces sleep has not been explained, but probably by diminishing the secretion of sensorial power, and then the voluntary motions become suspended previously to the irritative ones, as occurs in most dying persons. Another way of procuring sleep mechanically was related to me by Mr. Brindley, the famous canal engineer, who was brought up to the business of a mill-wright; he told me, that he had more than once seen the experiment of a man extending himself across the large stone of a corn-mill, and that by gradually letting the stone whirl, the man fell asleep, before the stone had gained its full velocity, and he supposed would have died without pain by the continuance or increase of the motion. In this case the centrifugal motion of the head and feet must accumulate the blood in both those extremities of the body, and thus compress the brain. Lastly, we should mention the application of cold; which, when in a less degree, produces watchfulness by the pain it occasions, and the tremulous convulsions of the subcutaneous muscles; but when it is applied in great degree, is said to produce sleep. To explain this effect it has been said, that as the vessels of the skin and extremities become first torpid by the want of the stimulus of heat, and as thence less blood is circulated through them, as appears from their paleness, a greater quantity of blood poured upon the brain produces sleep by its compression of that organ. But I should rather imagine, that the sensorial power becomes exhausted by the convulsive actions in consequence of the pain of cold, and of the voluntary exercise previously used to prevent it, and that the sleep is only the beginning to die, as the suspension of voluntary power in lingering deaths precedes for many hours the extinction of the irritative motions. 21. The following are the characteristic circumstances attending perfect sleep. 1. The power of volition is totally suspended. 2. The trains of ideas caused by sensation proceed with greater facility and vivacity; but become inconsistent with the usual order of nature. The muscular motions caused by sensation continue; as those concerned in our evacuations during infancy, and afterwards in digestion, and in priapismus. 3. The irritative muscular motions continue, as those concerned in the circulation, in secretion, in respiration. But the irritative sensual motions, or ideas, are not excited; as the immediate organs of sense are not stimulated into action by external objects, which are excluded by the external organs of sense; which are not in sleep adapted to their reception by the power of volition, as in our waking hours. 4. The associate motions continue; but their first link is not excited into action by volition, or by external stimuli. In all respects, except those above mentioned, the three last sensorial powers are somewhat increased in energy during the suspension of volition, owing to the consequent accumulation of the spirit of animation. * * * * * SECT. XIX. OF REVERIE. 1. _Various degrees of reverie._ 2. _Sleep-walkers. Case of a young lady. Great surprise at awaking. And total forgetfulness of what passed in reverie._ 3. _No suspension of volition in reverie._ 4. _Sensitive motions continue, and are consistent._ 5. _Irritative motions continue, but are not succeeded by sensation._ 6. _Volition necessary for the perception of feeble impressions._ 7. _Associated motions continue._ 8. _Nerves of sense are irritable in sleep, but not in reverie._ 9. _Somnambuli are not asleep. Contagion received but once._ 10. _Definition of reverie._ 1. When we are employed with great sensation of pleasure, or with great efforts of volition, in the pursuit of some interesting train of ideas, we cease to be conscious of our existence, are inattentive to time and place, and do not distinguish this train of sensitive and voluntary ideas from the irritative ones excited by the presence of external objects, though our organs of sense are furnished with their accustomed stimuli, till at length this interesting train of ideas becomes exhausted, or the appulses of external objects are applied with unusual violence, and we return with surprise, or with regret, into the common track of life. This is termed reverie or studium. In some constitutions these reveries continue a considerable time, and are not to be removed without greater difficulty, but are experienced in a less degree by us all; when we attend earnestly to the ideas excited by volition or sensation, with their associated connexions, but are at the same time conscious at intervals of the stimuli of surrounding bodies. Thus in being present at a play, or in reading a romance, some persons are so totally absorbed as to forget their usual time of sleep, and to neglect their meals; while others are said to have been so involved in voluntary study as not to have heard the discharge of artillery; and there is a story of an Italian politician, who could think so intensely on other subjects, as to be insensible to the torture of the rack. From hence it appears, that these catenations of ideas and muscular motions, which form the trains of reverie, are composed both of voluntary and sensitive associations of them; and that these ideas differ from those of delirium or of sleep, as they are kept consistent by the power of volition; and they differ also from the trains of ideas belonging to insanity, as they are as frequently excited by sensation as by volition. But lastly, that the whole sensorial power is so employed on these trains of complete reverie, that like the violent efforts of volition, as in convulsions or insanity; or like the great activity of the irritative motions in drunkenness; or of the sensitive motions in delirium; they preclude all sensation consequent to external stimulus. 2. Those persons, who are said to walk in their sleep, are affected with reverie to so great a degree, that it becomes a formidable disease; the essence of which consists in the inaptitude of the mind to attend to external stimuli. Many histories of this disease have been published by medical writers; of which there is a very curious one in the Lausanne Transactions. I shall here subjoin an account of such a case, with its cure, for the better illustration of this subject. A very ingenious and elegant young lady, with light eyes and hair, about the age of seventeen, in other respects well, was suddenly seized soon after her usual menstruation with this very wonderful malady. The disease began with vehement convulsions of almost every muscle of her body, with great but vain efforts to vomit, and the most violent hiccoughs, that can be conceived: these were succeeded in about an hour with a fixed spasm; in which one hand was applied to her head, and the other to support it: in about half an hour these ceased, and the reverie began suddenly, and was at first manifest by the look of her eyes and countenance, which seemed to express attention. Then she conversed aloud with imaginary persons with her eyes open, and could not for about an hour be brought to attend to the stimulus of external objects by any kind of violence, which it was proper to use; these symptoms returned in this order every day for five or six weeks. These conversations were quite consistent, and we could understand, what she supposed her imaginary companions to answer, by the continuation of her part of the discourse. Sometimes she was angry, at other times shewed much wit and vivacity, but was most frequently inclined to melancholy. In these reveries she sometimes sung over some music with accuracy, and repeated whole pages from the English poets. In repeating some lines from Mr. Pope's works she had forgot one word, and began again, endeavouring to recollect it; when she came to the forgotten word, it was shouted aloud in her ear, and this repeatedly, to no purpose; but by many trials she at length regained it herself. These paroxysms were terminated with the appearance of inexpressible surprise, and great fear, from which she was some minutes in recovering herself, calling on her sister with great agitation, and very frequently underwent a repetition of convulsions, apparently from the pain of fear. See Sect. XVII. 3. 7. After having thus returned for about an hour every day for two or three weeks, the reveries seemed to become less complete, and some of their circumstances varied; so that she could walk about the room in them without running against any of the furniture; though these motions were at first very unsteady and tottering. And afterwards she once drank a dish of tea, when the whole apparatus of the tea-table was set before her; and expressed some suspicion, that a medicine was put into it, and once seemed to smell of a tuberose, which was in flower in her chamber, and deliberated aloud about breaking it from the stem, saying, "it would make her sister so charmingly angry." At another time in her melancholy moments she heard the sound of a passing bell, "I wish I was dead," she cried, listening to the bell, and then taking off one of her shoes, as she sat upon the bed, "I love the colour black," says she, "a little wider, and a little longer, even this might make me a coffin!"--Yet it is evident, she was not sensible at this time, any more than formerly, of seeing or hearing any person about her; indeed when great light was thrown upon her by opening the shutters of the window, her trains of ideas seemed less melancholy; and when I have forcibly held her hands, or covered her eyes, she appeared to grow impatient, and would say, she could not tell what to do, for she could neither see nor move. In all these circumstances her pulse continued unaffected as in health. And when the paroxysm was over, she could never recollect a single idea of what had passed in it. This astonishing disease, after the use of many other medicines and applications in vain, was cured by very large doses of opium given about an hour before the expected returns of the paroxysms; and after a few relapses, at the intervals of three or four months, entirely disappeared. But she continued at times to have other symptoms of epilepsy. 3. We shall only here consider, what happened during the time of her reveries, as that is our present subject; the fits of convulsion belong to another part of this treatise. Sect. XXXIV. 1. 4. There seems to have been no suspension of volition during the fits of reverie, because she endeavoured to regain the lost idea in repeating the lines of poetry, and deliberated about breaking the tuberose, and suspected the tea to have been medicated. 4. The ideas and muscular movements depending on sensation were exerted with their usual vivacity, and were kept from being inconsistent by the power of volition, as appeared from her whole conversation, and was explained in Sect. XVII. 3. 7. and XVIII. 16. 5. The ideas and motions dependant on irritation during the first weeks of her disease, whilst the reverie was complete, were never succeeded by the sensation of pleasure or pain; as she neither saw, heard, nor felt any of the surrounding objects. Nor was it certain that any irritative motions succeeded the stimulus of external objects, till the reverie became less complete, and then she could walk about the room without running against the furniture of it. Afterwards, when the reverie became still less complete from the use of opium, some few irritations were at times succeeded by her attention to them. As when she smelt at a tuberose, and drank a dish of tea, but this only when she seemed voluntarily to attend to them. 6. In common life when we listen to distant sounds, or wish to distinguish objects in the night, we are obliged strongly to exert our volition to dispose the organs of sense to perceive them, and to suppress the other trains of ideas, which might interrupt these feeble sensations. Hence in the present history the strongest stimuli were not perceived, except when the faculty of volition was exerted on the organ of sense; and then even common stimuli were sometimes perceived: for her mind was so strenuously employed in pursuing its own trains of voluntary or sensitive ideas, that no common stimuli could so far excite her attention as to disunite them; that is, the quantity of volition or of sensation already existing was greater than any, which could be produced in consequence of common degrees of stimulation. But the few stimuli of the tuberose, and of the tea, which she did perceive, were such, as accidentally coincided with the trains of thought, which were passing in her mind; and hence did not disunite those trains, and create surprise. And their being perceived at all was owing to the power of volition preceding or coinciding with that of irritation. This explication is countenanced by a fact mentioned concerning a somnambulist in the Lausanne Transactions, who sometimes opened his eyes for a short time to examine, where he was, or where his ink-pot stood, and then shut them again, dipping his pen into the pot every now and then, and writing on, but never opening his eyes afterwards, although he wrote on from line to line regularly, and corrected some errors of the pen, or in spelling: so much easier was it to him to refer to his ideas of the positions of things, than to his perceptions of them. 7. The associated motions persisted in their usual channel, as appeared by the combinations of her ideas, and the use of her muscles, and the equality of her pulse; for the natural motions of the arterial system, though originally excited like other motions by stimulus, seem in part to continue by their association with each other. As the heart of a viper pulsates long after it is cut out of the body, and removed from the stimulus of the blood. 8. In the section on sleep, it was observed that the nerves of sense are equally alive and susceptible to irritation in that state, as when we are awake; but that they are secluded from stimulating objects, or rendered unfit to receive them: but in complete reverie the reverse happens, the immediate organs of sense are exposed to their usual stimuli; but are either not excited into action at all, or not into so great action, as to produce attention or sensation. The total forgetfulness of what passes in reveries; and the surprise on recovering from them, are explained in Section XVIII. 19. and in Section XVII. 3. 7. 9. It appears from hence, that reverie is a disease of the epileptic or cataleptic kind, since the paroxysms of this young lady always began and frequently terminated with convulsions; and though in its greatest degree it has been called somnambulation, or sleep-walking, it is totally different from sleep; because the essential character of sleep consists in the total suspension of volition, which in reverie is not affected; and the essential character of reverie consists not in the absence of those irritative motions of our senses, which are occasioned by the stimulus of external objects, but in their never being productive of sensation. So that during a fit of reverie that strange event happens to the whole system of nerves, which occurs only to some particular branches of them in those, who are a second time exposed to the action of contagious matter. If the matter of the small-pox be inserted into the arm of one, who has previously had that disease, it will stimulate the wound, but the general sensation or inflammation of the system does not follow, which constitutes the disease. See Sect. XII. 3. 6. XXXIII. 2. 8. 10. The following is the definition or character of complete reverie. 1. The irritative motions occasioned by internal stimuli continue, those from the stimuli of external objects are either not produced at all, or are never succeeded by sensation or attention, unless they are at the same time excited by volition. 2. The sensitive motions continue, and are kept consistent by the power of volition. 3. The voluntary motions continue undisturbed. 4. The associate motions continue undisturbed. Two other cases of reverie are related in Section XXXIV. 3. which further evince, that reverie is an effort of the mind to relieve some painful sensation, and is hence allied to convulsion, and to insanity. Another case is related in Class III. 1. 2. 2. * * * * * SECT. XX. OF VERTIGO. 1. _We determine our perpendicularity by the apparent motions of objects. A person hood-winked cannot walk in a straight line. Dizziness in looking from a tower, in a room stained with uniform lozenges, on riding over snow._ 2. _Dizziness from moving objects. A whirling-wheel. Fluctuations of a river. Experiment with a child._ 3. _Dizziness from our own motions and those of other objects._ 4. _Riding over a broad stream. Sea-sickness._ 5. _Of turning round on one foot. Dervises in Turkey. Attention of the mind prevents slight sea-sickness. After a voyage ideas of vibratory motions are still perceived on shore._ 6. _Ideas continue some time after they are excited. Circumstances of turning on one foot, standing on a tower, and walking in the dark, explained._ 7. _Irritative ideas of apparent motions. Irritative ideas of sounds. Battèment of the sound of bells and organ-pipes. Vertiginous noise in the head. Irritative motions of the stomach, intestines, and glands._ 8. _Symptoms that accompany vertigo. Why vomiting comes on in strokes of the palsy. By the motion of a ship. By injuries on the head. Why motion makes sick people vomit._ 9. _Why drunken people are vertiginous. Why a stone in the ureter, or bile-duct, produces vomiting._ 10. _Why after a voyage ideas of vibratory motions are perceived on shore._ 11. _Kinds of vertigo and their cure._ 12. _Definition of vertigo._ 1. In learning to walk we judge of the distances of the objects, which we approach, by the eye; and by observing their perpendicularity determine our own. This circumstance not having been attended to by the writers on vision, the disease called vertigo or dizziness has been little understood. When any person loses the power of muscular action, whether he is erect or in a sitting posture, he sinks down upon the ground; as is seen in fainting fits, and other instances of great debility. Hence it follows, that some exertion of muscular power is necessary to preserve our perpendicular attitude. This is performed by proportionally exerting the antagonist muscles of the trunk, neck, and limbs; and if at any time in our locomotions we find ourselves inclining to one side, we either restore our equilibrium by the efforts of the muscles on the other side, or by moving one of our feet extend the base, which we rest upon, to the new center of gravity. But the most easy and habitual manner of determining our want of perpendicularity, is by attending to the apparent motion of the objects within the sphere of distinct vision; for this apparent motion of objects, when we incline from our perpendicularity, or begin to fall, is as much greater than the real motion of the eye, as the diameter of the sphere of distinct vision is to our perpendicular height. Hence no one, who is hood-winked, can walk in a straight line for a hundred steps together; for he inclines so greatly, before he is warned of his want of perpendicularity by the sense of touch, not having the apparent motions of ambient objects to measure this inclination by, that he is necessitated to move one of his feet outwards, to the right or to the left, to support the new centre of gravity, and thus errs from the line he endeavours to proceed in. For the same reason many people become dizzy, when they look from the summit of a tower, which is raised much above all other objects, as these objects are out of the sphere of distinct vision, and they are obliged to balance their bodies by the less accurate feelings of their muscles. There is another curious phenomenon belonging to this place, if the circumjacent visible objects are so small, that we do not distinguish their minute parts; or so similar, that we do not know them from each other; we cannot determine our perpendicularity by them. Thus in a room hung with a paper, which is coloured over with similar small black lozenges or rhomboids, many people become dizzy; for when they begin to fall, the next and the next lozenge succeeds upon the eye; which they mistake for the first, and are not aware, that they have any apparent motion. But if you fix a sheet of paper, or draw any other figure, in the midst of these lozenges, the charm ceases, and no dizziness is perceptible.--The same occurs, when we ride over a plain covered with snow without trees or other eminent objects. 2. But after having compared visible objects at rest with the sense of touch, and learnt to distinguish their shapes and shades, and to measure our want of perpendicularity by their apparent motions, we come to consider them in real motion. Here a new difficulty occurs, and we require some experience to learn the peculiar mode of motion of any moving objects, before we can make use of them for the purposes of determining our perpendicularity. Thus some people become dizzy at the sight of a whirling wheel, or by gazing on the fluctuations of a river, if no steady objects are at the same time within the sphere of their distinct vision; and when a child first can stand erect upon his legs, if you gain his attention to a white handkerchief steadily extended like a sail, and afterwards make it undulate, he instantly loses his perpendicularity, and tumbles on the ground. 3. A second difficulty we have to encounter is to distinguish our own real movements from the apparent motions of objects. Our daily practice of walking and riding on horseback soon instructs us with accuracy to discern these modes of motion, and to ascribe the apparent motions of the ambient objects to ourselves; but those, which we have not acquired by repeated habit, continue to confound us. So as we ride on horseback the trees and cottages, which occur to us, appear at rest; we can measure their distances with our eye, and regulate our attitude by them; yet if we carelessly attend to distant hills or woods through a thin hedge, which is near us, we observe the jumping and progressive motions of them; as this is increased by the paralax of these objects; which we have not habituated ourselves to attend to. When first an European mounts an elephant sixteen feet high, and whose mode of motion he is not accustomed to, the objects seem to undulate, as he passes, and he frequently becomes sick and vertiginous, as I am well informed. Any other unusual movement of our bodies has the same effect, as riding backwards in a coach, swinging on a rope, turning round swiftly on one leg, scating on the ice, and a thousand others. So after a patient has been long confined to his bed, when he first attempts to walk, he finds himself vertiginous, and is obliged by practice to learn again the particular modes of the apparent motions of objects, as he walks by them. 4. A third difficulty, which occurs to us in learning to balance ourselves by the eye, is, when both ourselves and the circumjacent objects are in real motion. Here it is necessary, that we should be habituated to both these modes of motion in order to preserve our perpendicularity. Thus on horseback we accurately observe another person, whom we meet, trotting towards us, without confounding his jumping and progressive motion with our own, because we have been accustomed to them both; that is, to undergo the one, and to see the other at the same time. But in riding over a broad and fluctuating stream, though we are well experienced in the motions of our horse, we are liable to become dizzy from our inexperience in that of the water. And when first we go on ship-board, where the movements of ourselves, and the movements of the large waves are both new to us, the vertigo is almost unavoidable with the terrible sickness, which attends it. And this I have been assured has happened to several from being removed from a large ship into a small one; and again from a small one into a man of war. 5. From the foregoing examples it is evident, that, when we are surrounded with unusual motions, we lose our perpendicularity: but there are some peculiar circumstances attending this effect of moving objects, which we come now to mention, and shall hope from the recital of them to gain some insight into the manner of their production. When a child moves round quick upon one foot, the circumjacent objects become quite indistinct, as their distance increases their apparent motions; and this great velocity confounds both their forms, and their colours, as is seen in whirling round a many coloured wheel; he then loses his usual method of balancing himself by vision, and begins to stagger, and attempts to recover himself by his muscular feelings. This staggering adds to the instability of the visible objects by giving a vibratory motion besides their rotatory one. The child then drops upon the ground, and the neighbouring objects seem to continue for some seconds of time to circulate around him, and the earth under him appears to librate like a balance. In some seconds of time these sensations of a continuation of the motion of objects vanish; but if he continues turning round somewhat longer, before he falls, sickness and vomiting are very liable to succeed. But none of these circumstances affect those who have habituated themselves to this kind of motion, as the dervises in Turkey, amongst whom these swift gyrations are a ceremony of religion. In an open boat passing from Leith to Kinghorn in Scotland, a sudden change of the wind shook the undistended sail, and stopt our boat; from this unusual movement the passengers all vomited except myself. I observed, that the undulation of the ship, and the instability of all visible objects, inclined me strongly to be sick; and this continued or increased, when I closed my eyes, but as often as I bent my attention with energy on the management and mechanism of the ropes and sails, the sickness ceased; and recurred again, as often as I relaxed this attention; and I am assured by a gentleman of observation and veracity, that he has more than once observed, when the vessel has been in immediate danger, that the sea-sickness of the passengers has instantaneously ceased, and recurred again, when the danger was over. Those, who have been upon the water in a boat or ship so long, that they have acquired the necessary habits of motion upon that unstable element, at their return on land frequently think in their reveries, or between sleeping and waking, that they observe the room, they sit in, or some of its furniture, to librate like the motion of the vessel. This I have experienced myself, and have been told, that after long voyages, it is some time before these ideas entirely vanish. The same is observable in a less degree after having travelled some days in a stage coach, and particularly when we lie down in bed, and compose ourselves to sleep; in this case it is observable, that the rattling noise of the coach, as well as the undulatory motion, haunts us. The drunken vertigo, and the vulgar custom of rocking children, will be considered in the next Section. 6. The motions, which are produced by the power of volition, may be immediately stopped by the exertion of the same power on the antagonist muscles; otherwise these with all the other classes of motion continue to go on, some time after they are excited, as the palpitation of the heart continues after the object of fear, which occasioned it, is removed. But this circumstance is in no class of motions more remarkable than in those dependent on irritation; thus if any one looks at the sun, and then covers his eyes with his hand, he will for many seconds of time, perceive the image of the sun marked on his retina: a similar image of all other visible objects would remain some time formed on the retina, but is extinguished by the perpetual change of the motions of this nerve in our attention to other objects. To this must be added, that the longer time any movements have continued to be excited without fatigue to the organ, the longer will they continue spontaneously, after the excitement is withdrawn: as the taste of tobacco in the mouth after a person has been smoaking it. This taste remains so strong, that if a person continues to draw air through a tobacco pipe in the dark, after having been smoking some time, he cannot distinguish whether his pipe be lighted or not. From these two considerations it appears, that the dizziness felt in the head, after seeing objects in unusual motion, is no other than a continuation of the motions of the optic nerve excited by those objects and which engage our attention. Thus on turning round on one foot, the vertigo continues for some seconds of time after the person is fallen on the ground; and the longer he has continued to revolve, the longer will continue these successive motions of the parts of the optic nerve. _Additional Observations on _VERTIGO. After revolving with your eyes open till you become vertiginous, as soon as you cease to revolve, not only the circum-ambient objects appear to circulate round you in a direction contrary to that, in which you have been turning, but you are liable to roll your eyes forwards and backwards; as is well observed, and ingeniously demonstrated by Dr. Wells in a late publication on vision. The same occurs, if you revolve with your eyes closed, and open them immediately at the time of your ceasing to turn; and even during the whole time of revolving, as may be felt by your hand pressed lightly on your closed eyelids. To these movements of the eyes, of which he supposes the observer to be inconscious, Dr. Wells ascribes the apparent circumgyration of objects on ceasing to revolve. The cause of thus turning our eyes forwards, and then back again, after our body is at rest, depends, I imagine, on the same circumstance, which induces us to follow the indistinct spectra, which are formed on one side of the center of the retina, when we observe them apparently on clouds, as described in Sect. XL. 2. 2.; and then not being able to gain a more distinct vision of them, we turn our eyes back, and again and again pursue the flying shade. But this rolling of the eyes, after revolving till we become vertiginous, cannot cause the apparent circumgyration of objects, in a direction contrary to that in which we have been revolving, for the following reasons. 1. Because in pursuing a spectrum in the sky, or on the ground, as above mentioned, we perceive no retrograde motions of objects. 2. Because the apparent retrograde motions of objects, when we have revolved till we are vertiginous, continues much longer than the rolling of the eyes above described. 3. When we have revolved from right to left, the apparent motion of objects, when we stop, is from left to right; and when we have revolved from left to right, the apparent circulation of objects is from right to left; yet in both these cases the eyes of the revolver are seen equally to roll forwards and backwards. 4. Because this rolling of the eyes backwards and forwards takes place during our revolving, as may be perceived by the hand lightly pressed on the closed eyelids, and therefore exists before the effect ascribed to it. And fifthly, I now come to relate an experiment, in which the rolling of the eyes does not take place at all after revolving, and yet the vertigo is more distressing than in the situations above mentioned. If any one looks steadily at a spot in the ceiling over his head, or indeed at his own finger held up high over his head, and in that situation turns round till he becomes giddy; and then stops, and looks horizontally; he now finds, that the apparent rotation of objects is from above downwards, or from below upwards; that is, that the apparent circulation of objects is now vertical instead of horizontal, making part of a circle round the axis of his _eye_; and this without any rolling of his eyeballs. The reason of there being no rolling of the eyeballs, perceived after this experiment, is, because the images of objects are formed in rotation round the axis of the eye, and not from one side to the other of the axis of it; so that, as the eyeball has not power to turn in its socket round its own axis, it cannot follow the apparent motions of these evanescent spectra, either before or after the body is at rest. From all which arguments it is manifest, that these apparent retrograde gyrations of objects are not caused by the rolling of the eyeballs; first, because no apparent retrogression of objects is observed in other rollings of the eyes: secondly, because the apparent retrogression of objects continues many seconds after the rolling of the eyeballs ceases. Thirdly, because the apparent retrogression of objects is sometimes one way, and sometimes another, yet the rolling of the eyeballs is the same. Fourthly, because the rolling of the eyeballs exists before the apparent retrograde motions of objects is observed; that is, before the revolving person stops. And fifthly, because the apparent retrograde gyration of objects is produced, when there is no rolling of the eyeballs at all. Doctor Wells imagines, that no spectra can be gained in the eye, if a person revolves with his eyelids closed, and thinks this a sufficient argument against the opinion, that the apparent progression of the spectra of light or colours in the eye can cause the apparent retrogression of objects in the vertigo above described; but it is certain, when any person revolves in a light room with his eyes closed, that he nevertheless perceives differences of light both in quantity and colour through his eyelids, as he turns round; and readily gains spectra of those differences. And these spectra are not very different except in vivacity from those, which he acquires, when he revolves with unclosed eyes, since if he then revolves very rapidly the colours and forms of surrounding objects are as it were mixed together in his eye;. as when, the prismatic colours are painted on a wheel, they appear white as they revolve. The truth of this is evinced by the staggering or vertigo of men perfectly blind, when they turn round; which is not attended with apparent circulation of objects, but is a vertiginous disorder of the sense of touch. Blind men balance themselves by their sense of touch; which, being less adapted for perceiving small deviations from their perpendicular, occasions them to carry themselves more erect in walking. This method of balancing themselves by the direction of their pressure against the floor, becomes disordered by the unusual mode of action in turning round, and they begin to lose their perpendicularity, that is, they become vertiginous; but without any apparent circular motions of visible objects. It will appear from the following experiments, that the apparent progression of the ocular spectra of light or colours is the cause of the apparent retrogression of objects, after a person has revolved, till he is vertiginous. First, when a person turns round in a light room with his eyes open, but closes them before he stops, he will seem to be carried forwards in the direction he was turning for a short time after he stops. But if he opens his eyes again, the objects before him instantly appear to move in a retrograde direction, and he loses the sensation of being carried forwards. The same occurs if a person revolves in a light room with his eyes closed; when he stops, he seems to be for a time carried forwards, if his eyes are still closed; but the instant he opens them, the surrounding objects appear to move in retrograde gyration. From hence it may be concluded, that it is the sensation or imagination of our continuing to go forwards in the direction in which we were turning, that causes the apparent retrograde circulation of objects. Secondly, though there is an audible vertigo, as is known by the battement, or undulations of sound in the ears, which many vertiginous people experience; and though there is also a tangible vertigo, as when a blind person turns round, as mentioned above; yet as this circumgyration of objects is an hallucination or deception of the sense of sight, we are to look for the cause of our appearing to move forward, when we stop with our eyes closed after gyration, to some affection of this sense. Now, thirdly, if the spectra formed in the eye during our rotation, continue to change, when we stand still, like the spectra described in Sect. III. 3. 6. such changes must suggest to us the idea or sensation of our still continuing to turn round; as is the case, when we revolve in a light room, and close our eyes before we stop. And lastly, on opening our eyes in the situation above described, the objects we chance to view amid these changing spectra in the eye, must seem to move in a contrary direction; as the moon sometimes appears to move retrograde, when swift-gliding clouds are passing forwards so much nearer the eye of the beholder. To make observations on faint ocular spectra requires some degree of habit, and composure of mind, and even patience; some of those described in Sect. XL. were found difficult to see, by many, who tried them; now it happens, that the mind, during the confusion of vertigo, when all the other irritative tribes of motion, as well as those of vision, are in some degree disturbed, together with the fear of falling, is in a very unfit state for the contemplation of such weak sensations, as are occasioned by faint ocular spectra. Yet after frequently revolving, both with my eyes closed, and with them open, and attending to the spectra remaining in them, by shading the light from my eyelids more or less with my hand, I at length ceased to have the idea of going forward, after I stopped with my eyes closed; and saw changing spectra in my eyes, which seemed to move, as it were, over the field of vision; till at length, by repeated trials on sunny days, I persuaded myself, on opening my eyes, after revolving some time, on a shelf of gilded books in my library, that I could perceive the spectra in my eyes move forwards over one or two of the books, like the vapours in the air of a summer's day; and could so far undeceive myself, as to perceive the books to stand still. After more trials I sometimes brought myself to believe, that I saw changing spectra of lights and shades moving in my eyes, after turning round for some time, but did not imagine either the spectra or the objects to be in a state of gyration. I speak, however, with diffidence of these facts, as I could not always make the experiments succeed, when there was not a strong light in my room, or when my eyes were not in the most proper state for such observations. The ingenious and learned M. Sauvage has mentioned other theories to account for the apparent circumgyration of objects in vertiginous people. As the retrograde motions of the particles of blood in the optic arteries, by spasm, or by fear, as is seen in the tails of tadpoles, and membranes between the fingers of frogs. Another cause he thinks may be from the librations to one side, and to the other, of the crystalline lens in the eye, by means of involuntary actions of the muscles, which constitute the ciliary process. Both these theories lie under the same objection as that of Dr. Wells before mentioned; namely, that the apparent motions of objects, after the observer has revolved for some time, should appear to vibrate this way and that; and not to circulate uniformly in a direction contrary to that, in which the observer had revolved. M. Sauvage has, lastly, mentioned the theory of colours left in the eye, which he has termed impressions on the retina. He says, "Experience teaches us, that impressions made on the retina by a visible object remain some seconds after the object is removed; as appears from the circle of fire which we see, when a fire-stick is whirled round in the dark; therefore when we are carried round our own axis in a circle, we undergo a temporary vertigo, when we stop; because the impressions of the circumjacent objects remain for a time afterwards on the retina." Nosolog. Method. Clas. VIII. I. 1. We have before observed, that the changes of these colours remaining in the eye, evinces them to be motions of the fine terminations of the retina, and not impressions on it; as impressions on a passive substance must either remain, or cease intirely. See an additional note at the end of the second volume. Any one, who stands alone on the top of a high tower, if he has not been accustomed to balance himself by objects placed at such distances and with such inclinations, begins to stagger, and endeavours to recover himself by his muscular feelings. During this time the apparent motion of objects at a distance below him is very great, and the spectra of these apparent motions continue a little time after he has experienced them; and he is persuaded to incline the contrary way to counteract their effects; and either immediately falls, or applying his hands to the building, uses his muscular feelings to preserve his perpendicular attitude, contrary to the erroneous persuasions of his eyes. Whilst the person, who walks in the dark, staggers, but without dizziness; for he neither has the sensation of moving objects to take off his attention from his muscular feelings, nor has he the spectra of those motions continued on his retina to add to his confusion. It happens indeed sometimes to one landing on a tower, that the idea of his not having room to extend his base by moving one of his feet outwards, when he begins to incline, superadds fears to his other inconveniences; which like surprise, joy, or any great degree of sensation, enervates him in a moment, by employing the whole sensorial power, and by thus breaking all the associated trains and tribes of motion. 7. The irritative ideas of objects, whilst we are awake, are perpetually present to our sense of sight; as we view the furniture of our rooms, or the ground, we tread upon, throughout the whole day without attending to it. And as our bodies are never at perfect rest during our waking hours, these irritative ideas of objects are attended perpetually with irritative ideas of their apparent motions. The ideas of apparent motions are always irritative ideas, because we never attend to them, whether we attend to the objects themselves, or to their real motions, or to neither. Hence the ideas of the apparent motions of objects are a complete circle of irritative ideas, which continue throughout the day. Also during all our waking hours, there is a perpetual confused sound of various bodies, as of the wind in our rooms, the fire, distant conversations, mechanic business; this continued buzz, as we are seldom quite motionless, changes its loudness perpetually, like the sound of a bell; which rises and falls as long as it continues, and seems to pulsate on the ear. This any one may experience by turning himself round near a waterfall; or by striking a glass bell, and then moving the direction of its mouth towards the ears, or from them, as long as its vibrations continue. Hence this undulation of indistinct sound makes another concomitant circle of irritative ideas, which continues throughout the day. We hear this undulating sound, when we are perfectly at rest ourselves, from other sonorous bodies besides bells; as from two organ-pipes, which are nearly but not quite in unison, when they are sounded together. When a bell is struck, the circular form is changed into an eliptic one; the longest axis of which, as the vibrations continue, moves round the periphery of the bell; and when either axis of this elipse is pointed towards our ears, the sound is louder; and less when the intermediate parts of the elipse are opposite to us. The vibrations of the two organ-pipes may be compared to Nonius's rule; the sound is louder, when they coincide, and less at the intermediate times. But, as the sound of bells is the most familiar of those sounds, which have a considerable battement, the vertiginous patients, who attend to the irritative circles of sounds above described, generally compare it to the noise of bells. The peristaltic motions of our stomach and intestines, and the secretions of the various glands, are other circles of irritative motions, some of them more or less complete, according to our abstinence or satiety. So that the irritative ideas of the apparent motions of objects, the irritative battements of sounds, and the movements of our bowels and glands compose a great circle of irritative tribes of motion: and when one considerable part of this circle of motions becomes interrupted, the whole proceeds in confusion, as described in Section XVII. 1. 7. on Catenation of Motions. 8. Hence a violent vertigo, from whatever cause it happens, is generally attended with undulating noise in the head, perversions of the motions of the stomach and duodenum, unusual excretion of bile and gastric juice, with much pale urine, sometimes with yellowness of the skin, and a disordered secretion of almost every gland of the body, till at length the arterial system is affected, and fever succeeds. Thus bilious vomitings accompany the vertigo occasioned by the motion of a ship; and when the brain is rendered vertiginous by a paralytic affection of any part of the body, a vomiting generally ensues, and a great discharge of bile: and hence great injuries of the head from external violence are succeeded with bilious vomitings, and sometimes with abscesses of the liver. And hence, when a patient is inclined to vomit from other causes, as in some fevers, any motions of the attendants in his room, or of himself when he is raised or turned in his bed, presently induces the vomiting by superadding a degree of vertigo. 9. And conversely it is very usual with those, whose stomachs are affected from internal causes, to be afflicted with vertigo, and noise in the head; such is the vertigo of drunken people, which continues, when their eyes are closed, and themselves in a recumbent posture, as well as when they are in an erect posture, and have their eyes open. And thus the irritation of a stone in the bile-duct, or in the ureter, or an inflammation of any of the intestines, are accompanied with vomitings and vertigo. In these cases the irritative motions of the stomach, which are in general not attended to, become so changed by some unnatural stimulus, as to become uneasy, and excite our sensation or attention. And thus the other irritative trains of motions, which are associated with it, become disordered by their sympathy. The same happens, when a piece of gravel sticks in the ureter, or when some part of the intestinal canal becomes inflamed. In these cases the irritative muscular motions are first disturbed by unusual stimulus, and a disordered action of the sensual motions, or dizziness ensues. While in sea-sickness the irritative sensual motions, as vertigo, precedes; and the disordered irritative muscular motions, as those of the stomach in vomiting, follow. 10. When these irritative motions are disturbed, if the degree be not very great, the exertion of voluntary attention to any other object, or any sudden sensation, will disjoin these new habits of motion. Thus some drunken people have become sober immediately, when any accident has strongly excited their attention; and sea-sickness has vanished, when the ship has been in danger. Hence when our attention to other objects is most relaxed, as just before we fall asleep, or between our reveries when awake, these irritative ideas of motion and sound are most liable to be perceived; as those, who have been at sea, or have travelled long in a coach, seem to perceive the vibrations of the ship, or the rattling of the wheels, at these intervals; which cease again, as soon as they exert their attention. That is, at those intervals they attend to the apparent motions, and to the battement of sounds of the bodies around them, and for a moment mistake them for those real motions of the ship, and noise of wheels, which they had lately been accustomed to: or at these intervals of reverie, or on the approach of sleep, these supposed motions or sounds may be produced entirely by imagination. We may conclude from this account of vertigo, that sea-sickness is not an effort of nature to relieve herself, but a necessary consequence of the associations or catenations of animal motions. And may thence infer, that the vomiting, which attends the gravel in the ureter, inflammations of the bowels, and the commencement of some fevers, has a similar origin, and is not always an effort of the vis medicatrix naturæ. But where the action of the organ is the immediate consequence of the stimulating cause, it is frequently exerted to dislodge that stimulus, as in vomiting up an emetic drug; at other times, the action of an organ is a general effort to relieve pain, as in convulsions of the locomotive muscles; other actions drink up and carry on the fluids, as in absorption and secretion; all which may be termed efforts of nature to relieve, or to preserve herself. 11. The cure of vertigo will frequently depend on our previously investigating the cause of it, which from what has been delivered above may originate from the disorder of any part of the great tribes of irritative motions, and of the associate motions catenated with them. Many people, when they arrive at fifty or sixty years of age, are affected with slight vertigo; which is generally but wrongly ascribed to indigestion, but in reality arises from a beginning defect of their sight; as about this time they also find it necessary to begin to use spectacles, when they read small prints, especially in winter, or by candle light, but are yet able to read without them during the summer days, when the light is stronger. These people do not see objects so distinctly as formerly, and by exerting their eyes more than usual, they perceive the apparent motions of objects, and confound them with the real motions of them; and therefore cannot accurately balance themselves so as easily to preserve their perpendicularity by them. That is, the apparent motions of objects, which are at rest, as we move by them, should only excite irritative ideas: but as these are now become less distinct, owing to the beginning imperfection of our sight, we are induced _voluntarily_ to attend to them; and then these apparent motions become succeeded by sensation; and thus the other parts of the trains of irritative ideas, or irritative muscular motions, become disordered, as explained above. In these cases of slight vertigo I have always promised my patients, that they would get free from it in two or three months, as they should acquire the habit of balancing their bodies by less distinct objects, and have seldom been mistaken in my prognostic. There is an auditory vertigo, which is called a noise in the head, explained in No. 7. of this section, which also is very liable to affect people in the advance of life, and is owing to their hearing less perfectly than before. This is sometimes called a ringing, and sometimes a singing, or buzzing, in the ears, and is occasioned by our first experiencing a disagreeable sensation from our not being able distinctly to hear the sounds, we used formerly to hear distinctly. And this disagreeable sensation excites desire and consequent volition; and when we voluntarily attend to small indistinct sounds, even the whispering of the air in a room, and the pulsations of the arteries of the ear are succeeded by sensation; which minute sounds ought only to have produced irritative sensual motions, or unperceived ideas. See Section XVII. 3. 6. These patients after a while lose this auditory vertigo, by acquiring a new habit of not attending voluntarily to these indistinct sounds, but contenting themselves with the less accuracy of their sense of hearing. Another kind of vertigo begins with the disordered action of some irritative muscular motions, as those of the stomach from intoxication, or from emetics; or those of the ureter, from the stimulus of a stone lodged in it; and it is probable, that the disordered motions of some of the great congeries of glands, as of those which form the liver, or of the intestinal canal, may occasion vertigo in consequence of their motions being associated or catenated with the great circles of irritative motions; and from hence it appears, that the means of cure must be adapted to the cause. To prevent sea-sickness it is probable, that the habit of swinging for a week or two before going on shipboard might be of service. For the vertigo from failure of sight, spectacles may be used. For the auditory vertigo, æther may be dropt into the ear to stimulate the part, or to dissolve ear-wax, if such be a part of the cause. For the vertigo arising from indigestion, the peruvian bark and a blister are recommended. And for that owing to a stone in the ureter, venesection, cathartics, opiates, sal soda aerated. 12. Definition of vertigo. 1. Some of the irritative sensual, or muscular motions, which were usually not succeeded by sensation, are in this disease succeeded by sensation; and the trains or circles of motions, which were usually catenated with them, are interrupted, or inverted, or proceed in confusion. 2. The sensitive and voluntary motions continue undisturbed. 3. The associate trains or circles of motions continue; but their catenations with some of the irritative motions are disordered, or inverted, or dissevered. * * * * * SECT. XXI. OF DRUNKENNESS. 1. _Sleep from satiety of hunger. From rocking children. From uniform sounds._ 2. _Intoxication from common food after fatigue and inanition._ 3. _From wine or of opium. Chilness after meals. Vertigo. Why pleasure is produced by intoxication, and by swinging and rocking children. And why pain is relieved by it._ 4. _Why drunkards stagger and stammer, and are liable to weep._ 5. _And become delirious, sleepy, and stupid._ 6. _Or make pale urine and vomit._ 7. _Objects are seen double._ 8. _Attention of the mind diminishes drunkenness._ 9. _Disordered irritative motions of all the senses._ 10. _Diseases from drunkenness._ 11. _Definition of drunkenness._ 1. In the state of nature when the sense of hunger is appeased by the stimulus of agreeable food, the business of the day is over, and the human savage is at peace with the world, he then exerts little attention to external objects, pleasing reveries of imagination succeed, and at length sleep is the result: till the nourishment which he has procured, is carried over every part of the system to repair the injuries of action, and he awakens with fresh vigour, and feels a renewal of his sense of hunger. The juices of some bitter vegetables, as of the poppy and the laurocerasus, and the ardent spirit produced in the fermentation of the sugar found in vegetable juices, are so agreeable to the nerves of the stomach, that, taken in a small quantity, they instantly pacify the sense of hunger; and the inattention to external stimuli with the reveries of imagination, and sleep, succeeds, in the same manner as when the stomach is filled with other less intoxicating food. This inattention to the irritative motions occasioned by external stimuli is a very important circumstance in the approach of sleep, and is produced in young children by rocking their cradles: during which all visible objects become indistinct to them. An uniform soft repeated sound, as the murmurs of a gentle current, or of bees, are said to produce the same effect, by presenting indistinct ideas of inconsequential sounds, and by thus stealing our attention from other objects, whilst by their continued reiterations they become familiar themselves, and we cease gradually to attend to any thing, and sleep ensues. 2. After great fatigue or inanition, when the stomach is suddenly filled with flesh and vegetable food, the inattention to external stimuli, and the reveries of imagination, become so conspicuous as to amount to a degree of intoxication. The same is at any time produced by superadding a little wine or opium to our common meals; or by taking these separately in considerable quantity; and this more efficaciously after fatigue or inanition; because a less quantity of any stimulating material will excite an organ into energetic action, after it has lately been torpid from defect of stimulus; as objects appear more luminous, after we have been in the dark; and because the suspension of volition, which is the immediate cause of sleep, is sooner induced, after a continued voluntary exertion has in part exhausted the sensorial power of volition; in the same manner as we cannot contract a single muscle long together without intervals of inaction. 3. In the beginning of intoxication we are inclined to sleep, as mentioned above, but by the excitement of external circumstances, as of noise, light, business, or by the exertion of volition, we prevent the approaches of it, and continue to take into our stomach greater quantities of the inebriating materials. By these means the irritative movements of the stomach are excited into greater action than is natural; and in consequence all the irritative tribes and trains of motion, which are catenated with them, become susceptible of stronger action from their accustomed stimuli; because these motions are excited both by their usual irritation, and by their association with the increased actions of the stomach and lacteals. Hence the skin glows, and the heat of the body is increased, by the more energetic action of the whole glandular system; and pleasure is introduced in consequence of these increased motions from internal stimulus. According to Law 5. Sect. IV. on Animal Causation. From this great increase of irritative motions from internal stimulus, and the increased sensation introduced into the system in consequence; and secondly, from the increased sensitive motions in consequence of this additional quantity of sensation, so much sensorial power is expended, that the voluntary power becomes feebly exerted, and the irritation from the stimulus of external objects is less forcible; the external parts of the eye are not therefore voluntarily adapted to the distances of objects, whence the apparent motions of those objects either are seen double, or become too indistinct for the purpose of balancing the body, and vertigo is induced. Hence we become acquainted with that very curious circumstance, why the drunken vertigo is attended with an increase of pleasure; for the irritative ideas and motions occasioned by internal stimulus, that were not attended to in our sober hours, are now just so much increased as to be succeeded by pleasurable sensation, in the same manner as the more violent motions of our organs are succeeded by painful sensation. And hence a greater quantity of pleasurable sensation is introduced into the constitution; which is attended in some people with an increase of benevolence and good humour. If the apparent motions of objects is much increased, as when we revolve on one foot, or are swung on a rope, the ideas of these apparent motions are also attended to, and are succeeded with pleasureable sensation, till they become familiar to us by frequent use. Hence children are at first delighted with these kinds of exercise, and with riding, and failing, and hence rocking young children inclines them to sleep. For though in the vertigo from intoxication the irritative ideas of the apparent motions of objects are indistinct from their decrease of energy: yet in the vertigo occasioned by rocking or swinging the irritative ideas of the apparent motions of objects are increased in energy, and hence they induce pleasure into the system, but are equally indistinct, and in consequence equally unfit to balance ourselves by. This addition of pleasure precludes desire or aversion, and in consequence the voluntary power is feebly exerted, and on this account rocking young children inclines them to sleep. In what manner opium and wine act in relieving pain is another article, that well deserves our attention. There are many pains that originate from defect as well as from excess of stimulus; of these are those of the six appetites of hunger, thirst, lust, the want of heat, of distention, and of fresh air. Thus if our cutaneous capillaries cease to act from the diminished stimulus of heat, when we are exposed to cold weather, or our stomach is uneasy for want of food; these are both pains from defect of stimulus, and in consequence opium, which stimulates all the moving system into increased action, must relieve them. But this is not the case in those pains, which arise from excess of stimulus, as in violent inflammations: in these the exhibition of opium is frequently injurious by increasing the action of the system already too great, as in inflammation of the bowels mortification is often produced by the stimulus of opium. Where, however, no such bad consequences follow; the stimulus of opium, by increasing all the motions of the system, expends so much of the sensorial power, that the actions of the whole system soon become feebler, and in consequence those which produced the pain and inflammation. 4. When intoxication proceeds a little further, the quantity of pleasurable sensation is so far increased, that all desire ceases, for there is no pain in the system to excite it. Hence the voluntary exertions are diminished, staggering and stammering succeed; and the trains of ideas become more and more inconsistent from this defect of voluntary exertion, as explained in the sections on sleep and reverie, whilst those passions which are unmixed with volition are more vividly felt, and shewn with less reserve; hence pining love, or superstitious fear, and the maudling tear dropped on the remembrance of the most trifling distress. 5. At length all these circumstances are increased; the quantity of pleasure introduced into the system by the increased irritative muscular motions of the whole sanguiferous, and glandular, and absorbent systems, becomes so great, that the organs of sense are more forcibly excited into action by this internal pleasurable sensation, than by the irritation from the stimulus of external objects. Hence the drunkard ceases to attend to external stimuli, and as volition is now also suspended, the trains of his ideas become totally inconsistent as in dreams, or delirium: and at length a stupor succeeds from the great exhaustion of sensorial power, which probably does not even admit of dreams, and in which, as in apoplexy, no motions continue but those from internal stimuli, from sensation, and from association. 6. In other people a paroxysm of drunkenness has another termination; the inebriate, as soon as he begins to be vertiginous, makes pale urine in great quantities and very frequently, and at length becomes sick, vomits repeatedly, or purges, or has profuse sweats, and a temporary fever ensues with a quick strong pulse. This in some hours is succeeded by sleep; but the unfortunate bacchanalian does not perfectly recover himself till about the same time of the succeeding day, when his course of inebriation began. As shewn in Sect. XVII. 1. 7. on Catenation. The temporary fever with strong pulse is owing to the same cause as the glow on the skin mentioned in the third paragraph of this Section: the flow of urine and sickness arises from the whole system of irritative motions being thrown into confusion by their associations with each other; as in sea-sickness, mentioned in Sect. XX. 4. on Vertigo; and which is more fully explained in Section XXIX. on Diabetes. 7. In this vertigo from internal causes we see objects double, as two candles instead of one, which is thus explained. Two lines drawn through the axes of our two eyes meet at the object we attend to: this angle of the optic axes increases or diminishes with the less or greater distances of objects. All objects before or behind the place where this angle is formed, appear double; as any one may observe by holding up a pen between his eyes and the candle; when he looks attentively at a spot on the pen, and carelessly at the candle, it will appear double; and the reverse when he looks attentively at the candle and carelessly at the pen; so that in this case the muscles of the eye, like those of the limbs, stagger and are disobedient to the expiring efforts of volition. Numerous objects are indeed sometimes seen by the inebriate, occasioned by the refractions made by the tears, which stand upon his eye-lids. 8. This vertigo also continues, when the inebriate lies in his bed, in the dark, or with his eyes closed; and this more powerfully than when he is erect, and in the light. For the irritative ideas of the apparent motions of objects are now excited by irritation from internal stimulus, or by association with other irritative motions; and the inebriate, like one in a dream, believes the objects of these irritative motions to be present, and feels himself vertiginous. I have observed in this situation, so long as my eyes and mind were intent upon a book, the sickness and vertigo ceased, and were renewed again the moment I discontinued this attention; as was explained in the preceding account of sea-sickness. Some drunken people have been known to become sober instantly from some accident, that has strongly excited their attention, as the pain of a broken bone, or the news of their house being on fire. 9. Sometimes the vertigo from internal causes, as from intoxication, or at the beginning of some fevers, becomes so universal, that the irritative motions which belong to other organs of sense are succeeded by sensation or attention, as well as those of the eye. The vertiginous noise in the ears has been explained in Section XX. on Vertigo. The taste of the saliva, which in general is not attended to, becomes perceptible, and the patients complain of a bad taste in their mouth. The common smells of the surrounding air sometimes excite the attention of these patients, and bad smells are complained of, which to other people are imperceptible. The irritative motions that belong to the sense of pressure, or of touch, are attended to, and the patient conceives the bed to librate, and is fearful of falling out of it. The irritative motions belonging to the senses of distention, and of heat, like those above mentioned, become attended to at this time: hence we feel the pulsation of our arteries all over us, and complain of heat, or of cold, in parts of the body where there is no accumulation or diminution of actual heat. All which are to be explained, as in the last paragraph, by the irritative ideas belonging to the various senses being now excited by internal stimuli, or by their associations with other irritative motions. And that the inebriate, like one in a dream, believes the external objects, which usually caused these irritative ideas, to be now present. 10. The diseases in consequence of frequent inebriety, or of daily taking much vinous spirit without inebriety, consist in the paralysis, which is liable to succeed violent stimulation. Organs, whose actions are associated with others, are frequently more affected than the organ, which is stimulated into too violent action. See Sect. XXIV. 2. 8. Hence in drunken people it generally happens, that the secretory vessels of the liver become first paralytic, and a torpor with consequent gall-stones or schirrus of this viscus is induced with concomitant jaundice; otherwise it becomes inflamed in consequence of previous torpor, and this inflammation is frequently transferred to a more sensible part, which is associated with it, and produces the gout, or the rosy eruption of the face, or some other leprous eruption on the head, or arms, or legs. Sometimes the stomach is first affected, and paralysis of the lacteal system is induced: whence a total abhorrence from flesh-food, and general emaciation. In others the lymphatic system is affected with paralysis, and dropsy is the consequence. In some inebriates the torpor of the liver produces pain without apparent schirrus, or gall stones, or inflammation, or consequent gout, and in these epilepsy or insanity are often the consequence. All which will be more fully treated of in the course of the work. I am well aware, that it is a common opinion, that the gout is as frequently owing to gluttony in eating, as to intemperance in drinking fermented or spirituous liquors. To this I answer, that I have seen no person afflicted with the gout, who has not drank freely of fermented liquor, as wine and water, or small beer; though as the disposition to all the diseases, which have originated from intoxication, is in some degree hereditary, a less quantity of spirituous potation will induce the gout in those, who inherit the disposition from their parents. To which I must add, that in young people the rheumatism is frequently mistaken for the gout. Spice is seldom taken in such quantity as to do any material injury to the system, flesh-meats as well as vegetables are the natural diet of mankind; with these a glutton may be crammed up to the throat, and fed fat like a stalled ox; but he will not be diseased, unless he adds spirituous or fermented liquor to his food. This is well known in the distilleries, where the swine, which are fattened by the spirituous sediments of barrels, acquire diseased livers. But mark what happens to a man, who drinks a quart of wine or of ale, if he has not been habituated to it. He loses the use both of his limbs and of his understanding! He becomes a temporary idiot, and has a temporary stroke of the palsy! And though he slowly recovers after some hours, is it not reasonable to conclude, that a perpetual repetition of so powerful a poison must at length permanently affect him?--If a person accidentally becomes intoxicated by eating a few mushrooms of a peculiar kind, a general alarm is excited, and he is said to be poisoned, and emetics are exhibited; but so familiarised are we to the intoxication from vinous spirit, that it occasions laughter rather than alarm. There is however considerable danger in too hastily discontinuing the use of so strong a stimulus, lest the torpor of the system, or paralysis, should sooner be induced by the omission than by the continuance of this habit, when unfortunately acquired. A golden rule for determining the quantity, which may with safety be discontinued, is delivered in Sect. XII. 7. 8. 11. Definition of drunkenness. Many of the irritative motions are much increased in energy by internal stimulation. 2. A great additional quantity of pleasurable sensation is occasioned by this increased exertion of the irritative motions. And many sensitive motions are produced in consequence of this increased sensation. 3. The associated trains and tribes of motions, catenated with the increased irritative and sensitive motions, are disturbed, and proceed in confusion. 4. The faculty of volition is gradually impaired, whence proceeds the instability of locomotion, inaccuracy of perception, and inconsistency of ideas; and is at length totally suspended, and a temporary apoplexy succeeds. * * * * * SECT. XXII. OF PROPENSITY TO MOTION, REPETITION AND IMITATION. I. _Accumulation of sensorial power in hemiplagia, in sleep, in cold fit of fever, in the locomotive muscles, in the organs of sense. Produces propensity to action._ II. _Repetition by three sensorial powers. In rhimes and alliterations, in music, dancing, architecture, landscape-painting, beauty._ III. 1. _Perception consists in imitation. Four kinds of imitation._ 2. _Voluntary. Dogs taught to dance._ 3. _Sensitive. Hence sympathy, and all our virtues. Contagious matter of venereal ulcers, of hydrophobia, of jail-fever, of small-pox, produced by imitation, and the sex of the embryon._ 4. _Irritative imitation._ 5. _Imitations resolvable into associations._ I. 1. In the hemiplagia, when the limbs on one side have lost their power of voluntary motion, the patient is for many days perpetually employed in moving those of the other. 2. When the voluntary power is suspended during sleep, there commences a ceaseless flow of sensitive motions, or ideas of imagination, which compose our dreams. 3. When in the cold fit of an intermittent fever some parts of the system have for a time continued torpid, and have thus expended less than their usual expenditure of sensorial power; a hot fit succeeds, with violent action of those vessels, which had previously been quiescent. All these are explained from an accumulation of sensorial power during the inactivity of some part of the system. Besides the very great quantity of sensorial power perpetually produced and expended in moving the arterial, venous, and glandular systems, with the various organs or digestion, as described in Section XXXII. 3. 2. there is also a constant expenditure of it by the action of our locomotive muscles and organs of sense. Thus the thickness of the optic nerves, where they enter the eye, and the great expansion of the nerves of touch beneath the whole of the cuticle, evince the great consumption of sensorial power by these senses. And our perpetual muscular actions in the common offices of life, and in constantly preserving the perpendicularity of our bodies during the day, evince a considerable expenditure of the spirit of animation by our locomotive muscles. It follows, that if the exertion of these organs of sense and muscles be for a while intermitted, that some quantity of sensorial power must be accumulated, and a propensity to activity of some kind ensue from the increased excitability of the system. Whence proceeds the irksomeness of a continued attitude, and of an indolent life. However small this hourly accumulation of the spirit of animation may be, it produces a propensity to some kind of action; but it nevertheless requires either desire or aversion, either pleasure or pain, or some external stimulus, or a previous link of association, to excite the system into activity; thus it frequently happens, when the mind and body are so unemployed as not to possess any of the three first kinds of stimuli, that the last takes place, and consumes the small but perpetual accumulation of sensorial power. Whence some indolent people repeat the same verse for hours together, or hum the same tune. Thus the poet: Onward he trudged, not knowing what he sought, And whistled, as he went, for want of thought. II. The repetitions of motions may be at first produced either by volition, or by sensation, or by irritation, but they soon become easier to perform than any other kinds of action, because they soon become associated together, according to Law the seventh, Section IV. on Animal Causation. And because their frequency of repetition, if as much sensorial power be produced during every reiteration as is expended, adds to the facility of their production. If a stimulus be repeated at uniform intervals of time, as described in Sect. XII. 3. 3. the action, whether of our muscles or organs of sense, is produced with still greater facility or energy; because the sensorial power of association, mentioned above, is combined with the sensorial power of irritation; that is, in common language, the acquired habit assists the power of the stimulus. This not only obtains in the annual, lunar, and diurnal catenations of animal motions, as explained in Sect. XXXVI. which are thus performed with great facility and energy; but in every less circle of actions or ideas, as in the burthen of a song, or the reiterations of a dance. To the facility and distinctness, with which we hear sounds at repeated intervals, we owe the pleasure, which we receive from musical time, and from poetic time; as described in Botanic Garden, P. 2. Interlude 3. And to this the pleasure we receive from the rhimes and alliterations of modern verification; the source of which without this key would be difficult to discover. And to this likewise should be ascribed the beauty of the duplicature in the perfect tense of the Greek verbs, and of some Latin ones, as tango tetegi, mordeo momordi. There is no variety of notes referable to the gamut in the beating of the drum, yet if it be performed in musical time, it is agreeable to our ears; and therefore this pleasurable sensation must be owing to the repetition of the divisions of the sounds at certain intervals of time, or musical bars. Whether these times or bars are distinguished by a pause, or by an emphasis, or accent, certain it is, that this distinction is perpetually repeated; otherwise the ear could not determine instantly, whether the successions of sound were in common or in triple time. In common time there is a division between every two crotchets, or other notes of equivalent time; though the bar in written music is put after every fourth crotchet, or notes equivalent in time; in triple time the division or bar is after every three crotchets, or notes equivalent; so that in common time the repetition recurs more frequently than in triple time. The grave or heroic verses of the Greek and Latin poets are written in common time; the French heroic verses, and Mr. Anstie's humorous verses in his Bath Guide, are written in the same time as the Greek and Latin verses, but are one bar shorter. The English grave or heroic verses are measured by triple time, as Mr. Pope's translation of Homer. But besides these little circles of musical time, there are the greater returning periods, and the still more distant choruses, which, like the rhimes at the ends of verses, owe their beauty to repetition; that is, to the facility and distinctness with which we perceive sounds, which we expect to perceive, or have perceived before; or in the language of this work, to the greater ease and energy with which our organ is excited by the combined sensorial powers of association and irritation, than by the latter singly. A certain uniformity or repetition of parts enters the very composition of harmony. Thus two octaves nearest to each other in the scale commence their vibrations together after every second vibration of the higher one. And where the first, third, and fifth compose a chord the vibrations concur or coincide frequently, though less to than in the two octaves. It is probable that these chords bear some analogy to a mixture of three alternate colours in the sun's spectrum separated by a prism. The pleasure we receive from a melodious succession of notes referable to the gamut is derived from another source, viz. to the pandiculation or counteraction of antagonist fibres. See Botanic Garden, P. 2. Interlude 3. If to these be added our early associations of agreeable ideas with certain proportions of sound, I suppose, from these three sources springs all the delight of music, so celebrated by ancient authors, and so enthusiastically cultivated at present. See Sect. XVI. No. 10. on Instinct. This kind of pleasure arising from repetition, that is from the facility and distinctness, with which we perceive and understand repeated sensations, enters into all the agreeable arts; and when it is carried to excess is termed formality. The art of dancing like that of music depends for a great part of the pleasure, it affords, on repetition; architecture, especially the Grecian, consists of one part being a repetition of another; and hence the beauty of the pyramidal outline in landscape-painting; where one side of the picture may be said in some measure to balance the other. So universally does repetition contribute to our pleasure in the fine arts, that beauty itself has been defined by some writers to consist in a due combination of uniformity and variety. See Sect. XVI. 6. III. 1. Man is termed by Aristotle an imitative animal; this propensity to imitation not only appears in the actions of children, but in all the customs and fashions of the world: many thousands tread in the beaten paths of others, for one who traverses regions of his own discovery. The origin of this propensity of imitation has not, that I recollect, been deduced from any known principle; when any action presents itself to the view of a child, as of whetting a knife, or threading a needle, the parts of this action in respect of time, motion, figure, is imitated by a part of the retina of his eye; to perform this action therefore with his hands is easier to him than to invent any new action, because it consists in repeating with another set of fibres, viz. with the moving muscles, what he had just performed by some parts of the retina; just as in dancing we transfer the times of motion from the actions of the auditory nerves to the muscles of the limbs. Imitation therefore consists of repetition, which we have shewn above to be the easiest kind of animal action, and which we perpetually fall into, when we possess an accumulation of sensorial power, which is not otherwise called into exertion. It has been shewn, that our ideas are configurations of the organs of sense, produced originally in consequence of the stimulus of external bodies. And that these ideas, or configurations of the organs of sense, referable in some property a correspondent property of external matter; as the parts of the senses of light and of touch, which are excited into action, resemble in figure the figure of the stimulating body; and probably also the colour, and the quantity of density, which they perceive. As explained in Sect. XIV. 2. 2. Hence it appears, that our perceptions themselves are copies, that is, imitations of some properties of external matter; and the propensity to imitation is thus interwoven with our existence, as it is produced by the stimuli of external bodies, and is afterwards repeated by our volitions and sensations, and thus constitutes all the operations of our minds. 2. Imitations resolve themselves into four kinds, voluntary, sensitive, irritative, and associate. The voluntary imitations are, when we imitate deliberately the actions of others, either by mimicry, as in acting a play, or in delineating a flower; or in the common actions of our lives, as in our dress, cookery, language, manners, and even in our habits of thinking. Not only the greatest part of mankind learn all the common arts of life by imitating others, but brute animals seem capable of acquiring knowledge with greater facility by imitating each other, than by any methods by which we can teach them; as dogs and cats, when they are sick, learn of each other to eat grass; and I suppose, that by making an artificial dog perform certain tricks, as in dancing on his hinder legs, a living dog might be easily induced to imitate them; and that the readiest way of instructing dumb animals is by practising them with others of the same species, which have already learned the arts we wish to teach them. The important use of imitation in acquiring natural language is mentioned in Section XVI. 7. and 8. on Instinct. 3. The sensitive imitations are the immediate consequences of pleasure or pain, and these are often produced even contrary to the efforts of the will. Thus many young men on seeing cruel surgical operations become sick, and some even feel pain in the parts of their own bodies, which they see tortured or wounded in others; that is, they in some measure imitate by the exertions of their own fibres the violent actions, which they witnessed in those of others. In this case a double imitation takes place, first the observer imitates with the extremities of the optic nerve the mangled limbs, which are present before his eyes; then by a second imitation he excites to violent action of the fibres of his own limbs as to produce pain in those parts of his own body, which he saw wounded in another. In these pains produced by imitation the effect has some similarity to the cause, which distinguishes them from those produced by association; as the pains of the teeth, called tooth-edge, which are produced by association with disagreeable sounds, as explained in Sect. XVI. 10. The effect of this powerful agent, imitation, in the moral world, is mentioned in Sect. XVI. 7. as it is the foundation of all our intellectual sympathies with the pains and pleasures of others, and is in consequence the source of all our virtues. For in what consists our sympathy with the miseries, or with the joys, of our fellow creatures, but in an involuntary excitation of ideas in some measure similar or imitative of those, which we believe to exist in the minds of the persons, whom we commiserate or congratulate? There are certain concurrent or successive actions of some of the glands, or other parts of the body, which are possessed of sensation, which become intelligible from this propensity to imitation. Of these are the production of matter by the membranes of the fauces, or by the skin, in consequence of the venereal disease previously affecting the parts of generation. Since as no fever is excited, and as neither the blood of such patients, nor even the matter from ulcers of the throat, or from cutaneous ulcers, will by inoculation produce the venereal disease in others, as observed by Mr. Hunter, there is reason to conclude, that no contagious matter is conveyed thither by the blood-vessels, but that a milder matter is formed by the actions of the fine vessels in those membranes imitating each other. See Section XXXIII. 2. 9. In this disease the actions of these vessels producing ulcers on the throat and skin are imperfect imitations of those producing chanker, or gonorrhoea; since the matter produced by them is not infectious, while the imitative actions in the hydrophobia appear to be perfect resemblances, as they produce a material equally infectious with the original one, which induced them. The contagion from the bite of a mad dog differs from other contagious materials, from its being communicable from other animals to mankind, and from many animals to each other; the phenomena attending the hydrophobia are in some degree explicable on the foregoing theory. The infectious matter does not appear to enter the circulation, as it cannot be traced along the course of the lymphatics from the wound, nor is there any swelling of the lymphatic glands, nor does any fever attend, as occurs in the small-pox, and in many other contagious diseases; yet by some unknown process the disease is communicated from the wound to the throat, and that many months after the injury, so as to produce pain and hydrophobia, with a secretion of infectious saliva of the same kind, as that of the mad dog, which inflicted the wound. This subject is very intricate.--It would appear, that by certain morbid actions of the salivary glands of the mad dog, a peculiar kind of saliva is produced; which being instilled into a wound of another animal stimulates the cutaneous or mucous glands into morbid actions, but which are ineffectual in respect to the production of a similar contagious material; but the salivary glands by irritative sympathy are thrown into similar action, and produce an infectious saliva similar to that instilled into the wound. Though in many contagious fevers a material similar to that which produced the disease, is thus generated by imitation; yet there are other infectious materials, which do not thus propagate themselves, but which seem to act like slow poisons. Of this kind was the contagious matter, which produced the jail-fever at the assizes at Oxford about a century ago. Which, though fatal to so many, was not communicated to their nurses or attendants. In these cases, the imitations of the fine vessels, as above described, appear to be imperfect, and do not therefore produce a matter similar to that, which stimulates them; in this circumstance resembling the venereal matter in ulcers of the throat or skin, according to the curious discovery of Mr. Hunter above related, who found, by repeated inoculations, that it would not infect. Hunter on Venereal Disease, Part vi. ch. 1. Another example of morbid imitation is in the production of a great quantity of contagious matter, as in the inoculated small-pox, from a small quantity of it inserted into the arm, and probably diffused in the blood. These particles of contagious matter stimulate the extremities of the fine arteries of the skin, and cause them to imitate some properties of those particles of contagious matter, so as to produce a thousandfold of a similar material. See Sect. XXXIII. 2. 6. Other instances are mentioned in the Section on Generation, which shew the probability that the extremities of the seminal glands may imitate certain ideas of the mind, or actions of the organs of sense, and thus occasion the male or female sex of the embryon. See Sect. XXXIX. 6. 4. We come now to those imitations, which are not attended with sensation. Of these are all the irritative ideas already explained, as when the retina of the eye imitates by its action or configuration the tree or the bench, which I shun in walking past without attending to them. Other examples of these irritative imitations are daily observable in common life; thus one yawning person shall set a whole company a yawning; and some have acquired winking of the eyes or impediments of speech by imitating their companions without being conscious of it. 5. Besides the three species of imitations above described there may be some associate motions, which may imitate each other in the kind as well as in the quantity of their action; but it is difficult to distinguish them from the associations of motions treated of in Section XXXV. Where the actions of other persons are imitated there can be no doubt, or where we imitate a preconceived idea by exertion of our locomotive muscles, as in painting a dragon; all these imitations may aptly be referred to the sources above described of the propensity to activity, and the facility of repetition; at the same time I do not affirm, that all those other apparent sensitive and irritative imitations may not be resolvable into associations of a peculiar kind, in which certain distant parts of similar irritability or sensibility, and which have habitually acted together, may affect each other exactly with the same kinds of motion; as many parts are known to sympathise in the quantity of their motions. And that therefore they may be ultimately resolvable into associations of action, as described in Sect. XXXV. * * * * * SECT. XXIII. OF THE CIRCULATORY SYSTEM. I. _The heart and arteries have no antagonist muscles. Veins absorb the blood, propel it forwards, and distend the heart; contraction of the heart distends the arteries. Vena portarum._ II. _Glands which take their fluids from the blood. With long necks, with short necks._ III. _Absorbent system._ IV. _Heat given out from glandular secretions. Blood changes colour in the lungs and in the glands and capillaries._ V. _Blood is absorbed by veins, as chyle by lacteal vessels, otherwise they could not join their streams._ VI. _Two kinds of stimulus, agreeable and disagreeable. Glandular appetency. Glands originally possessed sensation._ I. We now step forwards to illustrate some of the phenomena of diseases, and to trace out their most efficacious methods of cure; and shall commence this subject with a short description of the circulatory system. As the nerves, whose extremities form our various organs of sense and muscles, are all joined, or communicate, by means of the brain, for the convenience perhaps of the distribution of a subtile ethereal fluid for the purpose of motion; so all those vessels of the body, which carry the grosser fluids for the purposes of nutrition, communicate with each other by the heart. The heart and arteries are hollow muscles, and are therefore indued with power of contraction in consequence of stimulus, like all other muscular fibres; but, as they have no antagonist muscles, the cavities of the vessels, which they form, would remain for ever closed, after they have contracted themselves, unless some extraneous power be applied to again distend them. This extraneous power in respect to the heart is the current of blood, which is perpetually absorbed by the veins from the various glands and capillaries, and pushed into the heart by a power probably very similar to that, which raises the sap in vegetables in the spring, which, according to Dr. Hale's experiment on the stump of a vine, exerted a force equal to a column of water above twenty feet high. This force of the current of blood in the veins is partly produced by their absorbent power, exerted at the beginning of every fine ramification; which may be conceived to be a mouth absorbing blood, as the mouths of the lacteals and lymphatics absorb chyle and lymph. And partly by their intermitted compression by the pulsations of their generally concomitant arteries; by which the blood is perpetually propelled towards the heart, as the valves in many veins, and the absorbent mouths in them all, will not suffer it to return. The blood, thus forcibly injected into the chambers of the heart, distends this combination of hollow muscles; till by the stimulus of distention they contract themselves; and, pushing forwards the blood into the arteries, exert sufficient force to overcome in less than a second of time the vis inertiæ, and perhaps some elasticity, of the very extensive ramifications of the two great systems of the aortal and pulmonary arteries. The power necessary to do this in so short a time must be considerable, and has been variously estimated by different physiologists. The muscular coats of the arterial system are then brought into action by the stimulus of distention, and propel the blood to the mouths, or through the convolutions, which precede the secretory apertures of the various glands and capillaries. In the vessels of the liver there is no intervention of the heart; but the vena portarum, which does the office of an artery, is distended by the blood poured into it from the mesenteric veins, and is by this distention stimulated to contract itself, and propel the blood to the mouths of the numerous glands, which compose that viscus. II. The glandular system of vessels may be divided into those, which take some fluid from the circulation; and those, which give something to it. Those, which take their fluid from the circulation are the various glands, by which the tears, bile, urine, perspiration, and many other secretions are produced; these glands probably consist of a mouth to select, a belly to digest, and an excretory aperture to emit their appropriated fluids; the blood is conveyed by the power of the heart and arteries to the mouths of these glands, it is there taken up by the living power of the gland, and carried forwards to its belly, and excretory aperture, where a part is separated, and the remainder absorbed by the veins for further purposes. Some of these glands are furnished with long convoluted necks or tubes, as the seminal ones, which are curiously seen when injected with quicksilver. Others seem to consist of shorter tubes, as that great congeries of glands, which constitute the liver, and those of the kidneys. Some have their excretory apertures opening into reservoirs, as the urinary and gall-bladders. And others on the external body, as those which secrete the tears, and perspirable matter. Another great system of glands, which have very short necks, are the capillary vessels; by which the insensible perspiration is secreted on the skin; and the mucus of various consistences, which lubricates the interstices of the cellular membrane, of the muscular fibres, and of all the larger cavities of the body. From the want of a long convolution of vessels some have doubted, whether these capillaries should be considered as glands, and have been led to conclude, that the perspirable matter rather exuded than was secreted. But the fluid of perspiration is not simple water, though that part of it, which exhales into the air may be such; for there is another part of it, which in a state of health is absorbed again; but which, when the absorbents are diseased, remains on the surface of the skin, in the form of scurf, or indurated mucus. Another thing, which shews their similitude to other glands, is their sensibility to certain affections of the mind; as is seen in the deeper colour of the skin in the blush of shame, or the greater paleness of it from fear. III. Another series of glandular vessels is called the absorbent system; these open their mouths into all the cavities, and upon all those surfaces of the body, where the excretory apertures of the other glands pour out their fluids. The mouths of the absorbent system drink up a part or the whole of these fluids, and carry them forwards by their living power to their respective glands, which are called conglobate glands. There these fluids undergo some change, before they pass on into the circulation; but if they are very acrid, the conglobate gland swells, and sometimes suppurates, as in inoculation of the small-pox, in the plague, and in venereal absorptions; at other times the fluid may perhaps continue there, till it undergoes some chemical change, that renders it less noxious; or, what is more likely, till it is regurgitated by the retrograde motion of the gland in spontaneous sweats or diarrhoeas, as disagreeing food is vomited from the stomach. IV. As all the fluids, that pass through these glands, and capillary vessels, undergo a chemical change, acquiring new combinations, the matter of heat is at the same time given out; this is apparent, since whatever increases insensible perspiration, increases the heat of the skin; and when the action of these vessels is much increased but for a moment, as in blushing, a vivid heat on the skin is the immediate consequence. So when great bilious secretions, or those of any other gland, are produced, heat is generated in the part in proportion to the quantity of the secretion. The heat produced on the skin by blushing may be thought by some too sudden to be pronounced a chemical effect, as the fermentations or new combinations taking place in a fluid is in general a slower process. Yet are there many chemical mixtures in which heat is given out as instantaneously; as in solutions of metals in acids, or in mixtures of essential oils and acids, as of oil of cloves and acid of nitre. So the bruised parts of an unripe apple become almost instantaneously sweet; and if the chemico-animal process of digestion be stopped for but a moment, as by fear, or even by voluntary eructation, a great quantity of air is generated, by the fermentation, which instantly succeeds the stop of digestion. By the experiments of Dr. Hales it appears, that an apple during fermentation gave up above six hundred times its bulk of air; and the materials in the stomach are such, and in such a situation, as immediately to run into fermentation, when digestion is impeded. As the blood passes through the small vessels of the lungs, which connect the pulmonary artery and vein, it undergoes a change of colour from a dark to a light red; which may be termed a chemical change, as it is known to be effected by an admixture of oxygene, or vital air; which, according to a discovery of Dr. Priestley, passes through the moist membranes, which constitute the sides of these vessels. As the blood passes through the capillary vessels, and glands, which connect the aorta and its various branches with their correspondent veins in the extremities of the body, it again loses the bright red colour, and undergoes some new combinations in the glands or capillaries, in which the matter of heat is given out from the secreted fluids. This process therefore, as well as the process of respiration, has some analogy to combustion, as the vital air or oxygene seems to become united to some inflammable base, and the matter of heat escapes from the new acid, which is thus produced. V. After the blood has passed these glands and capillaries, and parted with whatever they chose to take from it, the remainder is received by the veins, which are a set of blood-absorbing vessels in general corresponding with the ramifications of the arterial system. At the extremity of the fine convolutions of the glands the arterial force ceases; this in respect to the capillary vessels, which unite the extremities of the arteries with the commencement of the veins, is evident to the eye, on viewing the tail of a tadpole by means of a solar, or even by a common microscope, for globules of blood are seen to endeavour to pass, and to return again and again, before they become absorbed by the mouths of the veins; which returning of these globules evinces, that the arterial force behind them has ceased. The veins are furnished with valves like the lymphatic absorbents; and the great trunks of the veins, and of the lacteals and lymphatics, join together before the ingress of their fluids into the left chamber of the heart; both which evince, that the blood in the veins, and the lymph and chyle in the lacteals and lymphatics, are carried on by a similar force; otherwise the stream, which was propelled with a less power, could not enter the vessels, which contained the stream propelled with a greater power. From whence it appears, that the veins are a system of vessels absorbing blood, as the lacteals and lymphatics are a system of vessels absorbing chyle and lymph. See Sect. XXVII. 1. VI. The movements of their adapted fluids in the various vessels of the body are carried forwards by the actions of those vessels in consequence of two kinds of stimulus, one of which may be compared to a pleasurable sensation or desire inducing the vessel to seize, and, as it were, to swallow the particles thus selected from the blood; as is done by the mouths of the various glands, veins, and other absorbents, which may be called glandular appetency. The other kind of stimulus may be compared to disagreeable sensation, or aversion, as when the heart has received the blood, and is stimulated by it to push it forwards into the arteries; the same again stimulates the arteries to contract, and carry forwards the blood to their extremities, the glands and capillaries. Thus the mesenteric veins absorb the blood from the intestines by glandular appetency, and carry it forward to the vena portarum; which acting as an artery contracts itself by disagreeable stimulus, and pushes it to its ramified extremities, the various glands, which constitute the liver. It seems probable, that at the beginning of the formation of these vessels in the embryon, an agreeable sensation was in reality felt by the glands during secretion, as is now felt in the act of swallowing palatable food; and that a disagreeable sensation was originally felt by the heart from the distention occasioned by the blood, or by its chemical stimulus; but that by habit these are all become irritative motions; that is, such motions as do not affect the whole system, except when the vessels are diseased by inflammation. * * * * * SECT. XXIV. OF THE SECRETIONS OF SALIVA, AND OF TEARS, AND OF THE LACRYMAL SACK. I. _Secretion of saliva increased by mercury in the blood._ 1. _By the food in the mouth. Dryness of the mouth not from a deficiency of saliva._ 2. _By Sensitive ideas._ 3. _By volition._ 4. _By distasteful substances. It is secreted in a dilute and saline state. It then becomes more viscid._ 5. _By ideas of distasteful substances._ 6. _By nausea._ 7. _By aversion._ 8. _By catenation with stimulating substances in the ear._ II. 1. _Secretion of tears less in sleep. From stimulation of their excretory duct._ 2. _Lacrymal sack is a gland._ 3. _Its uses._ 4. _Tears are secreted, when the nasal duct is stimulated._ 5. _Or when it is excited by sensation._ 6. _Or by volition._ 7. _The lacrymal sack can regurgitate its contents into the eye._ 8. _More tears are secreted by association with the irritation of the nasal duct of the lacrymal sack, than the puncta lacrymalia can imbibe. Of the gout in the liver and stomach._ I. The salival glands drink up a certain fluid from the circumfluent blood, and pour it into the mouth. They are sometimes stimulated into action by the blood, that surrounds their origin, or by some part of that heterogeneous fluid: for when mercurial salts, or oxydes, are mixed with the blood, they stimulate these glands into unnatural exertions; and then an unusual quantity of saliva is separated. 1. As the saliva secreted by these glands is most wanted during the mastication of our food, it happens, when the terminations of their ducts in the mouth are stimulated into action, the salival glands themselves are brought into increased action at the same time by association, and separate a greater quantity of their juices from the blood; in the same manner as tears are produced in greater abundance during the stimulus of the vapour of onions, or of any other acrid material in the eye. The saliva is thus naturally poured into the mouth only during the stimulus of our food in mastication; for when there is too great an exhalation of the mucilaginous secretion from the membranes, which line the mouth, or too great an absorption of it, the mouth becomes dry, though there is no deficiency in the quantity of saliva; as in those who sleep with their mouths open, and in some fevers. 2. Though during the mastication of our natural food the salival glands are excited into action by the stimulus on their excretory ducts, and a due quantity of saliva is separated from the blood, and poured into the mouth; yet as this mastication of our food is always attended with a degree of pleasure; and that pleasurable sensation is also connected with our ideas of certain kinds of aliment; it follows, that when these ideas are reproduced, the pleasurable sensation arises along with them, and the salival glands are excited into action, and fill the mouth with saliva from this sensitive association, as is frequently seen in dogs, who slaver at the sight of food. 3. We have also a voluntary power over the action of these salival glands, for we can at any time produce a flow of saliva into our mouth, and spit out, or swallow it at will. 4. If any very acrid material be held in the mouth, as the root of pyrethrum, or the leaves of tobacco, the salival glands are stimulated into stronger action than is natural, and thence secrete a much larger quantity of saliva; which is at the same time more viscid than in its natural state; because the lymphatics, that open their mouths into the ducts of the salival glands, and on the membranes, which line the mouth, are likewise stimulated into stronger action, and absorb the more liquid parts of the saliva with greater avidity; and the remainder is left both in greater quantity and more viscid. The increased absorption in the mouth by some stimulating substances, which are called astringents, as crab juice, is evident from the instant dryness produced in the mouth by a small quantity of them. As the extremities of the glands are of exquisite tenuity, as appears by their difficulty of injection, it was necessary for them to secrete their fluids in a very dilute state; and, probably for the purpose of stimulating them into action, a quantity of neutral salt is likewise secreted or formed by the gland. This aqueous and saline part of all secreted fluids is again reabsorbed into the habit. More than half of some secreted fluids is thus imbibed from the reservoirs, into which they are poured; as in the urinary bladder much more than half of what is secreted by the kidneys becomes reabsorbed by the lymphatics, which are thickly dispersed around the neck of the bladder. This seems to be the purpose of the urinary bladders of fish, as otherwise such a receptacle for the urine could have been of no use to an animal immersed in water. 5. The idea of substances disagreeably acrid will also produce a quantity of saliva in the mouth; as when we smell very putrid vapours, we are induced to spit out our saliva, as if something disagreeable was actually upon our palates. 6. When disagreeable food in the stomach produces nausea, a flow of saliva is excited in the mouth by association; as efforts to vomit are frequently produced by disagreeable drugs in the mouth by the same kind of association. 7. A preternatural flow of saliva is likewise sometimes occasioned by a disease of the voluntary power; for if we think about our saliva, and determine not to swallow it, or not to spit it out, an exertion is produced by the will, and more saliva is secreted against our wish; that is, by our aversion, which bears the same analogy to desire, as pain does to pleasure; as they are only modifications of the same disposition of the sensorium. See Class IV. 3. 2. 1. 8. The quantity of saliva may also be increased beyond what is natural, by the catenation of the motions of these glands with other motions, or sensations, as by an extraneous body in the ear; of which I have known an instance; or by the application of stizolobium, siliqua hirsuta, cowhage, to the seat of the parotis, as some writers have affirmed. II. 1. The lacrymal gland drinks up a certain fluid from the circumfluent blood, and pours it on the ball of the eye, on the upper part of the external corner of the eyelids. Though it may perhaps be stimulated into the performance of its natural action by the blood, which surrounds its origin, or by some part of that heterogeneous fluid; yet as the tears secreted by this gland are more wanted at some times than at others, its secretion is variable, like that of the saliva above mentioned, and is chiefly produced when its excretory duct is stimulated; for in our common sleep there seems to be little or no secretion of tears; though they are occasionally produced by our sensations in dreams. Thus when any extraneous material on the eye-ball, or the dryness of the external covering of it, or the coldness of the air, or the acrimony of some vapours, as of onions, stimulates the excretory duct of the lacrymal gland, it discharges its contents upon the ball; a quicker secretion takes place in the gland, and abundant tears succeed, to moisten, clean, and lubricate the eye. These by frequent nictitation are diffused over the whole ball, and as the external angle of the eye in winking is closed sooner than the internal angle, the tears are gradually driven forwards, and downwards from the lacrymal gland to the puncta lacrymalia. 2. The lacrymal sack, with its puncta lacrymalia, and its nasal duct, is a complete gland; and is singular in this respect, that it neither derives its fluid from, nor disgorges it into the circulation. The simplicity of the structure of this gland, and both the extremities of it being on the surface of the body, makes it well worthy our minuter observation; as the actions of more intricate and concealed glands may be better understood from their analogy to this. 3. This simple gland consists of two absorbing mouths, a belly, and an excretory duct. As the tears are brought to the internal angle of the eye, these two mouths drink them up, being stimulated into action by this fluid, which they absorb. The belly of the gland, or lacrymal sack, is thus filled, in which the saline part of the tears is absorbed, and when the other end of the gland, or nasal duct, is stimulated by the dryness, or pained by the coldness of the air, or affected by any acrimonious dust or vapour in the nostrils, it is excited into action together with the sack, and the tears are disgorged upon the membrane, which lines the nostrils; where they serve a second purpose to moisten, clean, and lubricate, the organ of smell. 4. When the nasal duct of this gland is stimulated by any very acrid material, as the powder of tobacco, or volatile spirits, it not only disgorges the contents of its belly or receptacle (the lacrymal sack), and absorbs hastily all the fluid, that is ready for it in the corner of the eye; but by the association of its motions with those of the lacrymal gland, it excites that also into increased action, and a large flow of tears is poured into the eye. 5. This nasal duct is likewise excited into strong action by sensitive ideas, as in grief, or joy, and then also by its associations with the lacrymal gland it produces a great flow of tears without any external stimulus; as is more fully explained in Sect. XVI. 8. on Instinct. 6. There are some, famous in the arts of exciting compassion, who are said to have acquired a voluntary power of producing a flow of tears in the eye; which, from what has been said in the section on Instinct above mentioned, I should suspect, is performed by acquiring a voluntary power over the action of this nasal duct. 7. There is another circumstance well worthy our attention, that when by any accident this nasal duct is obstructed, the lacrymal sack, which is the belly or receptacle of this gland, by slight pressure of the finger is enabled to disgorge its contents again into the eye; perhaps the bile in the same manner, when the biliary ducts are obstructed, is returned into the blood by the vessels which secrete it? 8. A very important though minute occurrence must here be observed, that though the lacrymal gland is only excited into action, when we weep at a distressful tale, by its association with this nasal duct, as is more fully explained in Sect. XVI. 8; yet the quantity of tears secreted at once is more than the puncta lacrymalia can readily absorb; which shews _that the motions occasioned by associations are frequently more energetic than the original motions, by which they were occasioned_. Which we shall have occasion to mention hereafter, to illustrate, why pains frequently exist in a part distant from the cause of them, as in the other end of the urethra, when a stone stimulates the neck of the bladder. And why inflammations frequently arise in parts distant from their cause, as the gutta rosea of drinking people, from an inflamed liver. The inflammation of a part is generally preceded by a torpor or quiescence of it; if this exists in any large congeries of glands, as in the liver, or any membranous part, as the stomach, pain is produced and chilliness in consequence of the torpor of the vessels. In this situation sometimes an inflammation of the parts succeeds the torpor; at other times a distant more sensible part becomes inflamed; whose actions have previously been associated with it; and the torpor of the first part ceases. This I apprehend happens, when the gout of the foot succeeds a pain of the biliary duct, or of the stomach. Lastly, it sometimes happens, that the pain of torpor exists without any consequent inflammation of the affected part, or of any distant part associated with it, as in the membranes about the temple and eye-brows in hemicrania, and in those pains, which occasion convulsions; if this happens to gouty people, when it affects the liver, I suppose epileptic fits are produced; and, when it affects the stomach, death is the consequence. In these cases the pulse is weak, and the extremities cold, and such medicines as stimulate the quiescent parts into action, or which induce inflammation in them, or in any distant part, which is associated with them, cures the present pain of torpor, and saves the patient. I have twice seen a gouty inflammation of the liver, attended with jaundice; the patients after a few days were both of them affected with cold fits, like ague-fits, and their feet became affected with gout, and the inflammation of their livers ceased. It is probable, that the uneasy sensations about the stomach, and indigestion, which precedes gouty paroxysms, are generally owing to torpor or slight inflammation of the liver, and biliary ducts; but where great pain with continued sickness, with feeble pulse, and sensation of cold, affect the stomach in patients debilitated by the gout, that it is a torpor of the stomach itself, and destroys the patient from the great connexion of that viscus with the vital organs. See Sect. XXV. 17. * * * * * SECT. XXV. OF THE STOMACH AND INTESTINES. 1. _Of swallowing our food. Ruminating animals._ 2. _Action of the stomach._ 3. _Action of the intestines. Irritative motions connected with these._ 4. _Effects of repletion._ 5. _Stronger action of the stomach and intestines from more stimulating food._ 6. _Their action inverted by still greater stimuli. Or by disgustful ideas. Or by volition._ 7. _Other glands strengthen or invert their motions by sympathy._ 8. _Vomiting performed by intervals._ 9. _Inversion of the cutaneous absorbents._ 10. _Increased secretion of bile and pancreatic juice._ 11. _Inversion of the lacteals._ 12. _And of the bile-ducts._ 13. _Case of a cholera._ 14. _Further account of the inversion of lacteals._ 15. _Iliac passions. Valve of the colon._ 16. _Cure of the iliac passion._ 17. _Pain of gall-stone distinguished from pain of the stomach. Gout of the stomach from torpor, from inflammation. Intermitting pulse owing to indigestion. To overdose of foxglove. Weak pulse from emetics. Death from a blow on the stomach. From gout of the stomach._ 1. The throat, stomach, and intestines, may be considered as one great gland; which like the lacrymal sack above mentioned, neither begins nor ends in the circulation. Though the act of masticating our aliment belongs to the sensitive class of motions, for the pleasure of its taste induces the muscles of the jaw into action; yet the deglutition of it when masticated is generally, if not always, an irritative motion, occasioned by the application of the food already masticated to the origin of the pharinx; in the same manner as we often swallow our spittle without attending to it. The ruminating class of animals have the power to invert the motion of their gullet, and of their first stomach, from the stimulus of this aliment, when it is a little further prepared; as is their daily practice in chewing the cud; and appears to the eye of any one, who attends to them, whilst they are employed in this second mastication of their food. 2. When our natural aliment arrives into the stomach, this organ is simulated into its proper vermicular action; which beginning at the upper orifice of it, and terminating at the lower one, gradually mixes together and pushes forwards the digesting materials into the intestine beneath it. At the same time the glands, that supply the gastric juices, which are necessary to promote the chemical part of the process of digestion, are stimulated to discharge their contained fluids, and to separate a further supply from the blood-vessels: and the lacteals or lymphatics, which open their mouths into the stomach, are stimulated into action, and take up some part of the digesting materials. 3. The remainder of these digesting materials is carried forwards into the upper intestines, and stimulates them into their peristaltic motion similar to that of the stomach; which continues gradually to mix the changing materials, and pass them along through the valve of the colon to the excretory end of this great gland, the sphincter ani. The digesting materials produce a flow of bile, and of pancreatic juice, as they pass along the duodenum, by stimulating the excretory ducts of the liver and pancreas, which terminate in that intestine: and other branches of the absorbent or lymphatic system, called lacteals, are excited to drink up, as it passes, those parts of the digesting materials, that are proper for their purpose, by its stimulus on their mouths. 4. When the stomach and intestines are thus filled with their proper food, not only the motions of the gastric glands, the pancreas, liver, and lacteal vessels, are excited into action; but at the same time the whole tribe of irritative motions are exerted with greater energy, a greater degree of warmth, colour, plumpness, and moisture, is given to the skin from the increased action of those glands called capillary vessels; pleasurable sensation is excited, the voluntary motions are less easily exerted, and at length suspended; and sleep succeeds, unless it be prevented by the stimulus of surrounding objects, or by voluntary exertion, or by an acquired habit, which was originally produced by one or other of these circumstances, as is explained in Sect. XXI. on Drunkenness. At this time also, as the blood-vessels become replete with chyle, more urine is separated into the bladder, and less of it is reabsorbed; more mucus poured into the cellular membranes, and less of it reabsorbed; the pulse becomes fuller, and softer, and in general quicker. The reason why less urine and cellular mucus is absorbed after a full meal with sufficient drink is owing to the blood-vessels being fuller: hence one means to promote absorption is to decrease the resistance by emptying the vessels by venesection. From this decreased absorption the urine becomes pale as well as copious, and the skin appears plump as well as florid. By daily repetition of these movements they all become connected together, and make a diurnal circle of irritative action, and if one of this chain be disturbed, the whole is liable to be put into disorder. See Sect. XX. on Vertigo. 5. When the stomach and intestines receive a quantity of food, whose stimulus is greater than usual, all their motions, and those of the glands and lymphatics, are stimulated into stronger action than usual, and perform their offices with greater vigour and in less time: such are the effects of certain quantities of spice or of vinous spirit. 6. But if the quantity or duration of these stimuli are still further increased, the stomach and throat are stimulated into a motion, whose direction is contrary to the natural one above described; and they regurgitate the materials, which they contain, instead of carrying them forwards. This retrograde motion of the stomach may be compared to the stretchings of wearied limbs the contrary way, and is well elucidated by the following experiment. Look earnestly for a minute or two on an area an inch square of pink silk, placed in a strong light, the eye becomes fatigued, the colour becomes faint, and at length vanishes, for the fatigued eye can no longer be stimulated into direct motions; then on closing the eye a green spectrum will appear in it, which is a colour directly contrary to pink, and which will appear and disappear repeatedly, like the efforts in vomiting. See Section XXIX. 11. Hence all those drugs, which by their bitter or astringent stimulus increase the action of the stomach, as camomile and white vitriol, if their quantity is increased above a certain dose become emetics. These inverted motions of the stomach and throat are generally produced from the stimulus of unnatural food, and are attended with the sensation of nausea or sickness: but as this sensation is again connected with an idea of the distasteful food, which induced it; so an idea of nauseous food will also sometimes excite the action of nausea; and that give rise by association to the inversion of the motions of the stomach and throat. As some, who have had horse-flesh or dogs-flesh given them for beef or mutton, are said to have vomited many hours afterwards, when they have been told of the imposition. I have been told of a person, who had gained a voluntary command over these inverted motions of the stomach and throat, and supported himself by exhibiting this curiosity to the public. At these exhibitions he swallowed a pint of red rough gooseberries, and a pint of white smooth ones, brought them up in small parcels into his mouth, and restored them separately to the spectators, who called for red or white as they pleased, till the whole were redelivered. 7. At the same time that these motions of the stomach and throat are stimulated into inversion, some of the other irritative motions, that had acquired more immediate connexions with the stomach, as those of the gastric glands, are excited into stronger action by this association; and some other of these motions, which are more easily excited, as those of the gastric lymphatics, are inverted by their association with the retrograde motions of the stomach, and regurgitate their contents, and thus a greater quantity of mucus, and of lymph, or chyle, is poured into the stomach, and thrown up along with its contents. 8. These inversions of the motion of the stomach in vomiting are performed by intervals, for the same reason that many other motions are reciprocally exerted and relaxed; for during the time of exertion the stimulus, or sensation, which caused this exertion, is not perceived; but begins to be perceived again, as soon as the exertion ceases, and is some time in again producing its effect. As explained in Sect. XXXIV. on Volition, where it is shewn, that the contractions of the fibres, and the sensation of pain, which occasioned that exertion, cannot exist at the same time. The exertion ceases from another cause also, which is the exhaustion of the sensorial power of the part, and these two causes frequently operate together. 9. At the times of these inverted efforts of the stomach not only the lymphatics, which open their mouths into the stomach, but those of the skin also, are for a time inverted; for sweats are sometimes pushed out during the efforts of vomiting without an increase of heat. 10. But if by a greater stimulus the motions of the stomach are inverted still more violently or more permanently, the duodenum has its peristaltic motions inverted at the same time by their association with those of the stomach; and the bile and pancreatic juice, which it contains, are by the inverted motions brought up into the stomach, and discharged along with its contents; while a greater quantity of bile and pancreatic juice is poured into this intestine; as the glands, that secrete them, are by their association with the motions of the intestine excited into stronger action than usual. 11. The other intestines are by association excited into more powerful action, while the lymphatics, that open their mouths into them, suffer an inversion of their motions corresponding with the lymphatics of the stomach, and duodenum; which with a part of the abundant secretion of bile is carried downwards, and contributes both to stimulate the bowels, and to increase the quantity of the evacuations. This inversion of the motion of the lymphatics appears from the quantity of chyle, which comes away by stools; which is otherwise absorbed as soon as produced, and by the immense quantity of thin fluid, which is evacuated along with it. 12. But if the stimulus, which inverts the stomach, be still more powerful, or more permanent, it sometimes happens, that the motions of the biliary glands, and of their excretory ducts, are at the same time inverted, and regurgitate their contained bile into the blood-vessels, as appears by the yellow colour of the skin, and of the urine; and it is probable the pancreatic secretion may suffer an inversion at the same time, though we have yet no mark by which this can be ascertained. 13. Mr. ---- eat two putrid pigeons out of a cold pigeon-pye, and drank about a pint of beer and ale along with them, and immediately rode about five miles. He was then seized with vomiting, which was after a few periods succeeded by purging; these continued alternately for two hours; and the purging continued by intervals for six or eight hours longer. During this time he could not force himself to drink more than one pint in the whole; this great inability to drink was owing to the nausea, or inverted motions of the stomach, which the voluntary exertion of swallowing could seldom and with difficulty overcome; yet he discharged in the whole at least six quarts; whence came this quantity of liquid? First, the contents of the stomach were emitted, then of the duodenum, gall-bladder, and pancreas, by vomiting. After this the contents of the lower bowels, then the chyle, that was in the lacteal vessels, and in the receptacle of chyle, was regurgitated into the intestines by a retrograde motion of these vessels. And afterwards the mucus deposited in the cellular membrane, and on the surface of all the other membranes, seems to have been absorbed; and with the fluid absorbed from the air to have been carried up their respective lymphatic branches by the increased energy of their natural motions, and down the visceral lymphatics, or lacteals, by the inversion of their motions. 14. It may be difficult to invent experiments to demonstrate the truth of this inversion of some branches of the absorbent system, and increased absorption of others, but the analogy of these vessels to the intestinal canal, and the symptoms of many diseases, render this opinion more probable than many other received opinions of the animal oeconomy. In the above instance, after the yellow excrement was voided, the fluid ceased to have any smell, and appeared like curdled milk, and then a thinner fluid, and some mucus, were evacuated; did not these seem to partake of the chyle, of the mucous fluid from all the cells of the body, and lastly, of the atmospheric moisture? All these facts may be easily observed by any one, who takes a brisk purge. 15. Where the stimulus on the stomach, or on some other part of the intestinal canal, is still more permanent, not only the lacteal vessels, but the whole canal itself, becomes inverted from its associations: this is the iliac passion, in which all the fluids mentioned above are thrown up by the mouth. At this time the valve in the colon, from the inverted motions of that bowel, and the inverted action of this living valve, does not prevent the regurgitation of its contents. The structure of this valve may be represented by a flexile leathern pipe standing up from the bottom of a vessel of water: its sides collapse by the pressure of the ambient fluid, as a small part of that fluid passes through it; but if it has a living power, and by its inverted action keeps itself open, it becomes like a rigid pipe, and will admit the whole liquid to pass. See Sect. XXIX. 2. 5. In this case the patient is averse to drink, from the constant inversion of the motions of the stomach, and yet many quarts are daily ejected from the stomach, which at length smell of excrement, and at last seem to be only a thin mucilaginous or aqueous liquor. From whence is it possible, that this great quantity of fluid for many successive days can be supplied, after the cells of the body have given up their fluids, but from the atmosphere? When the cutaneous branch of absorbents acts with unnatural strength, it is probable the intestinal branch has its motions inverted, and thus a fluid is supplied without entering the arterial system. Could oiling or painting the skin give a check to this disease? So when the stomach has its motions inverted, the lymphatics of the stomach, which are most strictly associated with it, invert their motions at the same time. But the more distant branches of lymphatics, which are less strictly associated with it, act with increased energy; as the cutaneous lymphatics in the cholera, or iliac passion, above described. And other irritative motions become decreased, as the pulsations of the arteries, from the extra-derivation or exhaustion of the sensorial power. Sometimes when stronger vomiting takes place the more distant branches of the lymphatic system invert their motions with those of the stomach, and loose stools are produced, and cold sweats. So when the lacteals have their motions inverted, as during the operation of strong purges, the urinary and cutaneous absorbents have their motions increased to supply the want of fluid in the blood, as in great thirst; but after a meal with sufficient potation the urine is pale, that is, the urinary absorbents act weakly, no supply of water being wanted for the blood. And when the intestinal absorbents act too violently, as when too great quantities of fluid have been drank, the urinary absorbents invert their motions to carry off the superfluity, which is a new circumstance of association, and a temporary diabetes supervenes. 16. I have had the opportunity of seeing four patients in the iliac passion, where the ejected material smelled and looked like excrement. Two of these were so exhausted at the time I saw them, that more blood could not be taken from them, and as their pain had ceased, and they continued to vomit up every thing which they drank, I suspected that a mortification of the bowel had already taken place, and as they were both women advanced in life, and a mortification is produced with less preceding pain in old and weak people, these both died. The other two, who were both young men, had still pain and strength sufficient for further venesection, and they neither of them had any appearance of hernia, both recovered by repeated bleeding, and a scruple of calomel given to one, and half a dram to the other, in very small pills: the usual means of clysters, and purges joined with opiates, had been in vain attempted. I have thought an ounce or two of crude mercury in less violent diseases of this kind has been of use, by contributing to restore its natural motion to some part of the intestinal canal, either by its weight or stimulus; and that hence the whole tube recovered its usual associations of progressive peristaltic motion. I have in three cases seen crude mercury given in small doses, as one or two ounces twice a day, have great effect in stopping pertinacious vomitings. 17. Besides the affections above described, the stomach is liable, like many other membranes of the body, to torpor without consequent inflammation: as happens to the membranes about the head in some cases of hemicrania, or in general head-ach. This torpor of the stomach is attended with indigestion, and consequent flatulency, and with pain, which is usually called the cramp of the stomach, and is relievable by aromatics, essential oils, alcohol, or opium. The intrusion of a gall-stone into the common bile-duct from the gall-bladder is sometimes mistaken for a pain of the stomach, as neither of them are attended with fever; but in the passage of a gall-stone, the pain is confined to a less space, which is exactly where the common bile-duct enters the duodenum, as explained in Section XXX. 1. 3. Whereas in this gastrodynia the pain is diffused over the whole stomach; and, like other diseases from torpor, the pulse is weaker, and the extremities colder, and the general debility greater, than in the passage of a gall-stone; for in the former the debility is the consequence of the pain, in the latter it is the cause of it. Though the first fits of the gout, I believe, commence with a torpor of the liver; and the ball of the toe becomes inflamed instead of the membranes of the liver in consequence of this torpor, as a coryza or catarrh frequently succeeds a long exposure of the feet to cold, as in snow, or on a moist brick-floor; yet in old or exhausted constitutions, which have been long habituated to its attacks, it sometimes commences with a torpor of the stomach, and is transferable to every membrane of the body. When the gout begins with torpor of the stomach, a painful sensation of cold occurs, which the patient compares to ice, with weak pulse, cold extremities, and sickness; this in its slighter degree is relievable by spice, wine, or opium; in its greater degree it is succeeded by sudden death, which is owing to the sympathy of the stomach with the heart, as explained below. If the stomach becomes inflamed in consequence of this gouty torpor of it, or in consequence of its sympathy with some other part, the danger is less. A sickness and vomiting continues many days, or even weeks, the stomach rejecting every thing stimulant, even opium or alcohol, together with much viscid mucus; till the inflammation at length ceases, as happens when other membranes, as those of the joints, are the seat of gouty inflammation; as observed in Sect. XXIV. 2. 8. The sympathy, or association of motions, between those of the stomach and those of the heart, are evinced in many diseases. First, many people are occasionally affected with an intermission of their pulse for a few days, which then ceases again. In this case there is a stop of the motion of the heart, and at the same time a tendency to eructation from the stomach. As soon as the patient feels a tendency to the intermission of the motion of his heart, if he voluntarily brings up wind from his stomach, the stop of the heart does not occur. From hence I conclude that the stop of digestion is the primary disease; and that air is instantly generated from the aliment, which begins to ferment, if the digestive process is impeded for a moment, (see Sect. XXIII. 4.); and that the stop of the heart is in consequence of the association of the motions of these viscera, as explained in Sect. XXXV. 1. 4.; but if the little air, which is instantly generated during the temporary torpor of the stomach, be evacuated, the digestion recommences, and the temporary torpor of the heart does not follow. One patient, whom I lately saw, and who had been five or six days much troubled with this intermission of a pulsation of his heart, and who had hemicrania with some fever, was immediately relieved from them all by losing ten ounces of blood, which had what is termed an inflammatory crust on it. Another instance of this association between the motions of the stomach and heart is evinced by the exhibition of an over dose of foxglove, which induces an incessant vomiting, which is attended with very slow, and sometimes intermitting pulse.--Which continues in spite of the exhibition of wine and opium for two or three days. To the same association must be ascribed the weak pulse, which constantly attends the exhibition of emetics during their operation. And also the sudden deaths, which have been occasioned in boxing by a blow on the stomach; and lastly, the sudden death of those, who have been long debilitated by the gout, from the torpor of the stomach. See Sect. XXXV. 1. 4. * * * * * SECT. XXVI. OF THE CAPILLARY GLANDS AND MEMBRANES. I. 1. _The capillary vessels are glands._ 2. _Their excretory ducts. Experiments on the mucus of the intestines, abdomen, cellular membrane, and on the humours of the eye._ 3. _Scurf on the head, cough, catarrh, diarrhoea, gonorrhoea._ 4. _Rheumatism. Gout. Leprosy._ II. 1. _The most minute membranes are unorganized._ 2. _Larger membranes are composed of the ducts of the capillaries, and the mouths of the absorbents._ 3. _Mucilaginous fluid is secreted on their surfaces._ III. _Three kinds of rheumatism._ I. 1. The capillary-vessels are like all the other glands except the absorbent system, inasmuch as they receive blood from the arteries, separate a fluid from it, and return the remainder by the veins. 2. This series of glands is of the most extensive use, as their excretory ducts open on the whole external skin forming its perspirative pores, and on the internal surfaces of every cavity of the body. Their secretion on the skin is termed insensible perspiration, which in health is in part reabsorbed by the mouths of the lymphatics, and in part evaporated in the air; the secretion on the membranes, which line the larger cavities of the body, which have external openings, as the mouth and intestinal canal, is termed mucus, but is not however coagulable by heat; and the secretion on the membranes of those cavities of the body, which have no external openings, is called lymph or water, as in the cavities of the cellular membrane, and of the abdomen; this lymph however is coagulable by the heat of boiling water. Some mucus nearly as viscid as the white of egg, which was discharged by stool, did not coagulate, though I evaporated it to one fourth of the quantity, nor did the aqueous and vitreous humours of a sheep's eye coagulate by the like experiment: but the serosity from an anasarcous leg, and that from the abdomen of a dropsical person, and the crystalline humour of a sheep's eye, coagulated in the same heat. 3. When any of these capillary glands are stimulated into greater irritative actions, than is natural, they secrete a more copious material; and as the mouths of the absorbent system, which open in their vicinity, are at the same time stimulated into greater action, the thinner and more saline part of the secreted fluid is taken up again; and the remainder is not only more copious but also more viscid than natural. This is more or less troublesome or noxious according to the importance of the functions of the part affected: on the skin and bronchiæ, where this secretion ought naturally to evaporate, it becomes so viscid as to adhere to the membrane; on the tongue it forms a pellicle, which can with difficulty be scraped off; produces the scurf on the heads of many people; and the mucus, which is spit up by others in coughing. On the nostrils and fauces, when the secretion of these capillary glands is increased, it is termed simple catarrh; when in the intestines, a mucous diarrhoea; and in the urethra, or vagina, it has the name of gonorrhoea, or fluor albus. 4. When these capillary glands become inflamed, a still more viscid or even cretaceous humour is produced upon the surfaces of the membranes, which is the cause or the effect of rheumatism, gout, leprosy, and of hard tumours of the legs, which are generally termed scorbutic; all which will be treated of hereafter. II. 1. The whole surface of the body, with all its cavities and contents, are covered with membrane. It lines every vessel, forms every cell, and binds together all the muscular and perhaps the osseous fibres of the body; and is itself therefore probably a simpler substance than those fibres. And as the containing vessels of the body from the largest to the least are thus lined and connected with membranes, it follows that these membranes themselves consisted of unorganized materials. For however small we may conceive the diameters of the minutest vessels of the body, which escape our eyes and glasses, yet these vessels must consist of coats or sides, which are made up of an unorganized material, and which are probably produced from a gluten, which hardens after its production, like the silk or web of caterpillars and spiders. Of this material consist the membranes, which line the shells of eggs, and the shell itself, both which are unorganized, and are formed from mucus, which hardens after it is formed, either by the absorption of its more fluid part, or by its uniting with some part of the atmosphere. Such is also the production of the shells of snails, and of shell-fish, and I suppose of the enamel of the teeth. 2. But though the membranes, that compose the sides of the most minute vessels, are in truth unorganized materials, yet the larger membranes, which are perceptible to the eye, seem to be composed of an intertexture of the mouths of the absorbent system, and of the excretory ducts of the capillaries, with their concomitant arteries, veins, and nerves: and from this construction it is evident, that these membranes must possess great irritability to peculiar stimuli, though they are incapable of any motions, that are visible to the naked eye: and daily experience shews us, that in their inflamed state they have the greatest sensibility to pain, as in the pleurisy and paronychia. 3. On all these membranes a mucilaginous or aqueous fluid is secreted, which moistens and lubricates their surfaces, as was explained in Section XXIII. 2. Some have doubted, whether this mucus is separated from the blood by an appropriated set of glands, or exudes through the membranes, or is an abrasion or destruction of the surface of the membrane itself, which is continually repaired on the other side of it, but the great analogy between the capillary vessels, and the other glands, countenances the former opinion; and evinces, that these capillaries are the glands, that secrete it; to which we must add, that the blood in passing these capillary vessels undergoes a change in its colour from florid to purple, and gives out a quantity of heat; from whence, as in other glands, we must conclude that something is secreted from it. III. The seat of rheumatism is in the membranes, or upon them; but there are three very distinct diseases, which commonly are confounded under this name. First, when a membrane becomes affected with torpor, or inactivity of the vessels which compose it, pain and coldness succeed, as in the hemicrania, and other head-achs, which are generally termed nervous rheumatism; they exist whether the part be at rest or in motion, and are generally attended with other marks of debility. Another rheumatism is said to exist, when inflammation and swelling, as well as pain, affect some of the membranes of the joints, as of the ancles, wrists, knees, elbows, and sometimes of the ribs. This is accompanied with fever, is analogous to pleurisy and other inflammations, and is termed the acute rheumatism. A third disease is called chronic rheumatism, which is distinguished from that first mentioned, as in this the pain only affects the patient during the motion of the part, and from the second kind of rheumatism above described, as it is not attended with quick pulse or inflammation. It is generally believed to succeed the acute rheumatism of the same part, and that some coagulable lymph, or cretaceous, or calculous material, has been left on the membrane; which gives pain, when the muscles move over it, as some extraneous body would do, which was too insoluble to be absorbed. Hence there is an analogy between this chronic rheumatism and the diseases which produce gravel or gout-stones; and it may perhaps receive relief from the same remedies, such as aerated sal soda. * * * * * SECT. XXVII. OF HÆMORRHAGES. I. _The veins are absorbent vessels._ 1. _Hæmorrhages from inflammation. Case of hæmorrhage from the kidney cured by cold bathing. Case of hæmorrhage from the nose cured by cold immersion._ II. _Hæmorrhage from venous paralysis. Of Piles. Black stools. Petechiæ. Consumption. Scurvy of the lungs. Blackness of the face and eyes in epileptic fits. Cure of hæmorrhages from venous inability._ I. As the imbibing mouths of the absorbent system already described open on the surface, and into the larger cavities of the body, so there is another system of absorbent vessels, which are not commonly esteemed such, I mean the veins, which take up the blood from the various glands and capillaries, after their proper fluids or secretions have been separated from it. The veins resemble the other absorbent vessels; as the progression of their contents is carried on in the same manner in both, they alike absorb their appropriated fluids, and have valves to prevent its regurgitation by the accidents of mechanical violence. This appears first, because there is no pulsation in the very beginnings of the veins, as is seen by microscopes; which must happen, if the blood was carried into them by the actions of the arteries. For though the concurrence of various venous streams of blood from different distances must prevent any pulsation in the larger branches, yet in the very beginnings of all these branches a pulsation must unavoidably exist, if the circulation in them was owing to the intermitted force of the arteries. Secondly, the venous absorption of blood from the penis, and from the teats of female animals after their erection, is still more similar to the lymphatic absorption, as it is previously poured into cells, where all arterial impulse must cease. There is an experiment, which seems to evince this venous absorption, which consists in the external application of a stimulus to the lips, as of vinegar, by which they become instantly pale; that is, the bibulous mouths of the veins by this stimulus are excited to absorb the blood faster, than it can be supplied by the usual arterial exertion. See Sect. XXIII. 5. There are two kinds of hæmorrhages frequent in diseases, one is where the glandular or capillary action is too powerfully exerted, and propels the blood forwards more hastily, than the veins can absorb it; and the other is, where the absorbent power of the veins is diminished, or a branch of them is become totally paralytic. 1. The former of these cases is known by the heat of the part, and the general fever or inflammation that accompanies the hæmorrhage. An hæmorrhage from the nose or from the lungs is sometimes a crisis of inflammatory diseases, as of the hepatitis and gout, and generally ceases spontaneously, when the vessels are considerably emptied. Sometimes the hæmorrhage recurs by daily periods accompanying the hot fits of fever, and ceasing in the cold fits, or in the intermissions; this is to be cured by removing the febrile paroxysms, which will be treated of in their place. Otherwise it is cured by venesection, by the internal or external preparations of lead, or by the application of cold, with an abstemious diet, and diluting liquids, like other inflammations. Which by inducing a quiescence on those glandular parts, that are affected, prevents a greater quantity of blood from being protruded forwards, than the veins are capable of absorbing. Mr. B---- had an hæmorrhage from his kidney, and parted with not less than a pint of blood a day (by conjecture) along with his urine for above a fortnight: venesections, mucilages, balsams, preparations of lead, the bark, alum, and dragon's blood, opiates, with a large blister on his loins, were separately tried, in large doses, to no purpose. He was then directed to bathe in a cold spring up to the middle of his body only, the upper part being covered, and the hæmorrhage diminished at the first, and ceased at the second immersion. In this case the external capillaries were rendered quiescent by the coldness of the water, and thence a less quantity of blood was circulated through them; and the internal capillaries, or other glands, became quiescent from their irritative associations with the external ones; and the hæmorrhage was stopped a sufficient time for the ruptured vessels to contract their apertures, or for the blood in those apertures to coagulate. Mrs. K---- had a continued haemorrhage from her nose for some days; the ruptured vessel was not to be reached by plugs up the nostrils, and the sensibility of her fauces was such that nothing could be born behind the uvula. After repeated venesection, and other common applications, she was directed to immerse her whole head into a pail of water, which was made colder by the addition of several handfuls of salt, and the hæmorrhage immediately ceased, and returned no more; but her pulse continued hard, and she was necessitated to lose blood from the arm on the succeeding day. Query, might not the cold bath instantly stop hæmorrhages from the lungs in inflammatory cases?--for the shortness of breath of those, who go suddenly into cold water, is not owing to the accumulation of blood in the lungs, but to the quiescence of the pulmonary capillaries from association, as explained in Section XXXII. 3. 2. II. The other kind of hæmorrhage is known from its being attended with a weak pulse, and other symptoms of general debility, and very frequently occurs in those, who have diseased livers, owing to intemperance in the use of fermented liquors. These constitutions are shewn to be liable to paralysis of the lymphatic absorbents, producing the various kinds of dropsies in Section XXIX. 5. Now if any branch of the venous system loses its power of absorption, the part swells, and at length bursts and discharges the blood, which the capillaries or other glands circulate through them. It sometimes happens that the large external veins of the legs burst, and effuse their blood; but this occurs most frequently in the veins of the intestines, as the vena portarum is liable to suffer from a schirrus of the liver opposing the progression of the blood, which is absorbed from the intestines. Hence the piles are a symptom of hepatic obstruction, and hence the copious discharges downwards or upwards of a black material, which has been called melancholia, or black bile; but is no other than the blood, which is probably discharged from the veins of the intestines. J.F. Meckel, in his Experimenta de Finibus Vasorum, published at Berlin, 1772, mentions his discovery of a communication of a lymphatic vessel with the gastric branch of the vena portarum. It is possible, that when the motion of the lymphatic becomes retrograde in some diseases, that blood may obtain a passage into it, where it anastomoses with the vein, and thus be poured into the intestines. A discharge of blood with the urine sometimes attends diabetes, and may have its source in the same manner. Mr. A----, who had been a hard drinker, and had the gutta rosacea on his face and breast, after a stroke of the palsy voided near a quart of a black viscid material by stool: on diluting it with water it did not become yellow, as it must have done if it had been inspissated bile, but continued black like the grounds of coffee. But any other part of the venous system may become quiescent or totally paralytic as well as the veins of the intestines: all which occur more frequently in those who have diseased livers, than in any others. Hence troublesome bleedings of the nose, or from the lungs with a weak pulse; hence hæmorrhages from the kidneys, too great menstruation; and hence the oozing of blood from every part of the body, and the petechiæ in those fevers, which are termed putrid, and which is erroneously ascribed to the thinness of the blood: for the blood in inflammatory diseases is equally fluid before it coagulates in the cold air. Is not that hereditary consumption, which occurs chiefly in dark-eyed people about the age of twenty, and commences with slight pulmonary hæmorrhages without fever, a disease of this kind?--These hæmorrhages frequently begin during sleep, when the irritability of the lungs is not sufficient in these patients to carry on the circulation without the assistance of volition; for in our waking hours, the motions of the lungs are in part voluntary, especially if any difficulty of breathing renders the efforts of volition necessary. See Class I. 2. 1. 3. and Class III. 2. 1. 12. Another species of pulmonary consumption which seems more certainly of scrophulous origin is described in the next Section, No. 2. I have seen two cases of women, of about forty years of age, both of whom were seized with quick weak pulse, with difficult respiration, and who spit up by coughing much viscid mucus mixed with dark coloured blood. They had both large vibices on their limbs, and petechiæ; in one the feet were in danger of mortification, in the other the legs were oedematous. To relieve the difficult respiration, about six ounces of blood were taken from one of them, which to my surprise was sizy, like inflamed blood: they had both palpitations or unequal pulsations of the heart. They continued four or five weeks with pale and bloated countenances, and did not cease spitting phlegm mixed with black blood, and the pulse seldom slower than 130 or 135 in a minute. This blood, from its dark colour, and from the many vibices and petechiæ, seems to have been venous blood; the quickness of the pulse, and the irregularity of the motion of the heart, are to be ascribed to debility of that part of the system; as the extravasation of blood originated from the defect of venous absorption. The approximation of these two cases to sea-scurvy is peculiar, and may allow them to be called scorbutus pulmonalis. Had these been younger subjects, and the paralysis of the veins had only affected the lungs, it is probable the disease would have been a pulmonary consumption. Last week I saw a gentleman of Birmingham, who had for ten days laboured under great palpitation of his heart, which was so distinctly felt by the hand, as to discountenance the idea of there being a fluid in the pericardium. He frequently spit up mucus stained with dark coloured blood, his pulse very unequal and very weak, with cold hands and nose. He could not lie down at all, and for about ten days past could not sleep a minute together, but waked perpetually with great uneasiness. Could those symptoms be owing to very extensive adhesions of the lungs? or is this a scorbutus pulmonalis? After a few days he suddenly got so much better as to be able to sleep many hours at a time by the use of one grain of powder of foxglove twice a day, and a grain of opium at night. After a few days longer, the bark was exhibited, and the opium continued with some wine; and the palpitations of his heart became much relieved, and he recovered his usual degree of health, but died suddenly some months afterwards. In epileptic fits the patients frequently become black in the face, from the temporary paralysis of the venous system of this part. I have known two instances where the blackness has continued many days. M. P----, who had drank intemperately, was seized with the epilepsy when he was in his fortieth year; in one of these fits the white part of his eyes was left totally black with effused blood; which was attended with no pain or heat, and was in a few weeks gradually absorbed, changing colour as is usual with vibices from bruises. The hæmorrhages produced from the inability of the veins to absorb the refluent blood, is cured by opium, the preparations of steel, lead, the bark, vitriolic acid, and blisters; but these have the effect with much more certainty, if a venesection to a few ounces, and a moderate cathartic with four or six grains of calomel be premised, where the patient is not already too much debilitated; as one great means of promoting the absorption of any fluid consists in previously emptying the vessels, which are to receive it. * * * * * SECT. XXVIII. OF THE PARALYSIS OF THE ABSORBENT SYSTEM. I. _Paralysis of the lacteals, atrophy. Distaste to animal food._ II. _Cause of dropsy. Cause of herpes. Scrophula. Mesenteric consumption. Pulmonary consumption. Why ulcers in the lungs are so difficult to heal._ The term paralysis has generally been used to express the loss of voluntary motion, as in the hemiplagia, but may with equal propriety be applied to express the disobediency of the muscular fibres to the other kinds of stimulus; as to those of irritation or sensation. I. There is a species of atrophy, which has not been well understood; when the absorbent vessels of the stomach and intestines have been long inured to the stimulus of too much spirituous liquor, they at length, either by the too sudden omission of fermented or spirituous potation, or from the gradual decay of nature, become in a certain degree paralytic; now it is observed in the larger muscles of the body, when one side is paralytic, the other is more frequently in motion, owing to the less expenditure of sensorial power in the paralytic limbs; so in this case the other part of the absorbent system acts with greater force, or with greater perseverance, in consequence of the paralysis of the lacteals; and the body becomes greatly emaciated in a small time. I have seen several patients in this disease, of which the following are the circumstances. 1. They were men about fifty years of age, and had lived freely in respect to fermented liquors. 2. They lost their appetite to animal food. 3. They became suddenly emaciated to a great degree. 4. Their skins were dry and rough. 5. They coughed and expectorated with difficulty a viscid phlegm. 6. The membrane of the tongue was dry and red, and liable to become ulcerous. The inability to digest animal food, and the consequent distaste to it, generally precedes the dropsy, and other diseases, which originate from spirituous potation. I suppose when the stomach becomes inirritable, that there is at the same time a deficiency of gastric acid; hence milk seldom agrees with these patients, unless it be previously curdled, as they have not sufficient gastric acid to curdle it; and hence vegetable food, which is itself acescent, will agree with their stomachs longer than animal food, which requires more of the gastric acid for its digestion. In this disease the skin is dry from the increased absorption of the cutaneous lymphatics, the fat is absorbed from the increased absorption of the cellular lymphatics, the mucus of the lungs is too viscid to be easily spit up by the increased absorption of the thinner parts of it, the membrana sneideriana becomes dry, covered with hardened mucus, and at length becomes inflamed and full of aphthæ, and either these sloughs, or pulmonary ulcers, terminate the scene. II. The immediate cause of dropsy is the paralysis of some other branches of the absorbent system, which are called lymphatics, and which open into the larger cavities of the body, or into the cells of the cellular membrane; whence those cavities or cells become distended with the fluid, which is hourly secreted into them for the purpose of lubricating their surfaces. As is more fully explained in No. 5. of the next Section. As those lymphatic vessels consist generally of a long neck or mouth, which drinks up its appropriated fluid, and of a conglobate gland, in which this fluid undergoes some change, it happens, that sometimes the mouth of the lymphatic, and sometimes the belly or glandular part of it, becomes totally or partially paralytic. In the former case, where the mouths of the cutaneous lymphatics become torpid or quiescent, the fluid secreted on the skin ceases to be absorbed, and erodes the skin by its saline acrimony, and produces eruptions termed herpes, the discharge from which is as salt, as the tears, which are secreted too fast to be reabsorbed, as in grief, or when the puncta lacrymalia are obstructed, and which running down the cheek redden and inflame the skin. When the mouths of the lymphatics, which open on the mucous membrane of the nostrils, become torpid, as on walking into the air in a frosty morning; the mucus, which continues to be secreted, has not its aqueous and saline part reabsorbed, which running over the upper lip inflames it, and has a salt taste, if it falls on the tongue. When the belly, or glandular part of these lymphatics, becomes torpid, the fluid absorbed by its mouth stagnates, and forms a tumour in the gland. This disease is called the scrophula. If these glands suppurate externally, they gradually heal, as those of the neck; if they suppurate without an opening on the external habit, as the mesenteric glands, a hectic fever ensues, which destroys the patient; if they suppurate in the lungs, a pulmonary consumption ensues, which is believed thus to differ from that described in the preceding Section, in respect to its seat or proximate cause. It is remarkable, that matter produced by suppuration will lie concealed in the body many weeks, or even months, without producing hectic fever; but as soon as the wound is opened, so as to admit air to the surface of the ulcer, a hectic fever supervenes, even in very few hours, which is probably owing to the azotic part of the atmosphere rather than to the oxygene; because those medicines, which contain much oxygene, as the calces or oxydes of metals, externally applied, greatly contribute to heal ulcers, of these are the solutions of lead and mercury, and copper in acids, or their precipitates. Hence when wounds are to be healed by the first intention, as it is called, it is necessary carefully to exclude the air from them. Hence we have one cause, which prevents pulmonary ulcers from healing, which is their being perpetually exposed to the air. Both the dark-eyed patients, which are affected with pulmonary ulcers from deficient venous absorption, as described in Section. XXVII. 2. and the light-eyed patients from deficient lymphatic absorption, which we are now treating of, have generally large apertures of the iris; these large pupils of the eyes are a common mark of want of irritability; and it generally happens, that an increase of sensibility, that is, of motions in consequence of sensation, attends these constitutions. See Sect. XXXI. 2. Whence inflammations may occur in these from stagnated fluids more frequently than in those constitutions, which possess more irritability and less sensibility. Great expectations in respect to the cure of consumptions, as well as of many other diseases, are produced by the very ingenious exertions of DR. BEDDOES; who has established an apparatus for breathing various mixtures of airs or gasses, at the hot-wells near Bristol, which well deserves the attention of the public. DR. BEDDOES very ingeniously concludes, from the florid colour of the blood of consumptive patients, that it abounds in oxygene; and that the redness of their tongues, and lips, and the fine blush of their cheeks shew the presence of the same principle, like flesh reddened by nitre. And adds, that the circumstance of the consumptions of pregnant women being stopped in their progress during pregnancy, at which time their blood may be supposed to be in part deprived of its oxygene, by oxygenating the blood of the foetus, is a forceable argument in favour of this theory; which must soon be confirmed or confuted by his experiments. See Essay on Scurvy, Consumption, &c. by Dr. Beddoes. Murray. London. Also Letter to Dr. Darwin, by the same. Murray. London. * * * * * SECT. XXIX. ON THE RETROGRADE MOTIONS OF THE ABSORBENT SYSTEM. I. _Account of the absorbent system._ II. _The valves of the absorbent vessels may suffer their fluids to regurgitate in some diseases._ III. _Communication from the alimentary canal to the bladder by means of the absorbent vessels._ IV. _The phenomena of diabetes explained._ V. 1. _The phenomena of dropsies explained._ 2. _Cases of the use of foxglove._ VI. _Of cold sweats._ VII. _Translations of matter, of chyle, of milk, of urine, operation of purging drugs applied externally._ VIII. _Circumstances by which the fluids, that are effused by the retrograde motions of the absorbent vessels, are distinguished._ IX. _Retrograde motions of vegetable juices._ X. _Objections answered._ XI. _The causes, which induce the retrograde motions of animal vessels, and the medicines by which the natural motions are restored._ _N.B. The following Section is a translation of a part of a Latin thesis written by the late Mr. Charles Darwin, which was printed with his prize-dissertation on a criterion between matter and mucus in 1780. Sold by Cadell, London._ I. _Account of the Absorbent System._ 1. The absorbent system of vessels in animal bodies consists of several branches, differing in respect to their situations, and to the fluids, which they absorb. The intestinal absorbents open their mouths on the internal surfaces of the intestines; their office is to drink up the chyle and the other fluids from the alimentary canal; and they are termed lacteals, to distinguish them from the other absorbent vessels, which have been termed lymphatics. Those, whose mouths are dispersed on the external skin, imbibe a great quantity of water from the atmosphere, and a part of the perspirable matter, which does not evaporate, and are termed cutaneous absorbents. Those, which arise from the internal surface of the bronchia, and which imbibe moisture from the atmosphere, and a part of the bronchial mucus, are called pulmonary absorbents. Those, which open their innumerable mouths into the cells of the whole cellular membrane; and whose use is to take up the fluid, which is poured into those cells, after it has done its office there; may be called cellular absorbents. Those, which arise from the internal surfaces of the membranes, which line the larger cavities of the body, as the thorax, abdomen, scrotum, pericardium, take up the mucus poured into those cavities; and are distinguished by the names of their respective cavities. Whilst those, which arise from the internal surfaces of the urinary bladder, gall-bladder, salivary ducts, or other receptacles of secreted fluids, may take their names from those fluids; the thinner parts of which it is their office to absorb: as urinary, bilious, or salivary absorbents. 2. Many of these absorbent vessels, both lacteals and lymphatics, like some of the veins, are replete with valves: which seem designed to assist the progress of their fluids, or at least to prevent their regurgitation; where they are subjected to the intermitted pressure of the muscular, or arterial actions in their neighbourhood. These valves do not however appear to be necessary to all the absorbents, any more than to all the veins; since they are not found to exist in the absorbent system of fish; according to the discoveries of the ingenious, and much lamented Mr. Hewson. Philos. Trans. v. 59, Enquiries into the Lymph. Syst. p. 94. 3. These absorbent vessels are also furnished with glands, which are called conglobate glands; whose use is not at present sufficiently investigated; but it is probable that they resemble the conglomerate glands both in structure and in use, except that their absorbent mouths are for the conveniency of situation placed at a greater distance from the body of the gland. The conglomerate glands open their mouths immediately into the sanguiferous vessels, which bring the blood, from whence they absorb their respective fluids, quite up to the gland: but these conglobate glands collect their adapted fluids from very distant membranes, or cysts, by means of mouths furnished with long necks for this purpose; and which are called lacteals, or lymphatics. 4. The fluids, thus collected from various parts of the body, pass by means of the thoracic duct into the left subclavian near the jugular vein; except indeed that those collected from the right side of the head and neck, and from the right arm, are carried into the right subclavian vein: and sometimes even the lymphatics from the right side of the lungs are inserted into the right subclavian vein; whilst those of the left side of the head open but just into the summit of the thoracic duct. 5. In the absorbent system there are many anastomoses of the vessels, which seem of great consequence to the preservation of health. These anastomoses are discovered by dissection to be very frequent between the intestinal and urinary lymphatics, as mentioned by Mr. Hewson, (Phil. Trans. v. 58.) 6. Nor do all the intestinal absorbents seem to terminate in the thoracic duct, as appears from some curious experiments of D. Munro, who gave madder to some animals, having previously put a ligature on the thoracic duct, and found their bones, and the serum of their blood, coloured red. II. _The Valves of the Absorbent System may suffer their Fluids to regurgitate in some Diseases._ 1. The many valves, which occur in the progress of the lymphatic and lacteal vessels, would seem insuperable obstacles to the regurgitation of their contents. But as these valves are placed in vessels, which are indued with life, and are themselves indued with life also; and are very irritable into those natural motions, which absorb, or propel the fluids they contain; it is possible, in some diseases, where these valves or vessels are stimulated into unnatural exertions, or are become paralytic, that during the diastole of the part of the vessel to which the valve is attached, the valve may not so completely close, as to prevent the relapse of the lymph or chyle. This is rendered more probable, by the experiments of injecting mercury, or water, or suet, or by blowing air down these vessels: all which pass the valves very easily, contrary to the natural course of their fluids, when the vessels are thus a little forcibly dilated, as mentioned by Dr. Haller, Elem. Physiol. t. iii. s. 4. "The valves of the thoracic duct are few, some assert they are not more than twelve, and that they do not very accurately perform their office, as they do not close the whole area of the duct, and thence may permit chyle to repass them downwards. In living animals, however, though not always, yet more frequently than in the dead, they prevent the chyle from returning. The principal of these valves is that, which presides over the insertion of the thoracic duct, into the subclavian vein; many have believed this also to perform the office of a valve, both to admit the chyle into the vein, and to preclude the blood from entering the duct; but in my opinion it is scarcely sufficient for this purpose." Haller, Elem. Phys. t. vii. p. 226. 2. The mouths of the lymphatics seem to admit water to pass through them after death, the inverted way, easier than the natural one; since an inverted bladder readily lets out the water with which it is filled; whence it may be inferred, that there is no obstacle at the mouths of these vessels to prevent the regurgitation of their contained fluids. I was induced to repeat this experiment, and having accurately tied the ureters and neck of a fresh ox's bladder, I made an opening at the fundus of it; and then, having turned it inside outwards, filled it half full with water, and was surprised to see it empty itself so hastily. I thought the experiment more apposite to my purpose by suspending the bladder with its neck downwards, as the lymphatics are chiefly spread upon this part of it, as shewn by Dr. Watson, Philos. Trans. v. 59. p. 392. 3. In some diseases, as in the diabetes and scrophula, it is probable the valves themselves are diseased, and are thence incapable of preventing the return of the fluids they should support. Thus the valves of the aorta itself have frequently been found schirrous, according to the dissections of Mons. Lieutaud, and have given rise to an interrupted pulse, and laborious palpitations, by suffering a return of part of the blood into the heart. Nor are any parts of the body so liable to schirrosity as the lymphatic glands and vessels, insomuch that their schirrosities have acquired a distinct name, and been termed scrophula. 4. There are valves in other parts of the body, analogous to those of the absorbent system, and which are liable, when diseased, to regurgitate their contents: thus the upper and lower orifices of the stomach are closed by valves, which, when too great quantities of warm water have been drank with a design to promote vomiting, have sometimes resisted the utmost efforts of the abdominal muscles, and diaphragm: yet, at other times, the upper valve, or cardia, easily permits the evacuation of the contents of the stomach; whilst the inferior valve, or pylorus, permits the bile, and other contents of the duodenum, to regurgitate into the stomach. 5. The valve of the colon is well adapted to prevent the retrograde motion of the excrements; yet, as this valve is possessed of a living power, in the iliac passion, either from spasm, or other unnatural exertions, it keeps itself open, and either suffers or promotes the retrograde movements of the contents of the intestines below; as in ruminating animals the mouth of the first stomach seems to be so constructed, as to facilitate or assist the regurgitation of the food; the rings of the oesophagus afterwards contracting themselves in inverted order. De Haeu, by means of a syringe, forced so much water into the rectum intestinum of a dog, that he vomited it in a full stream from his mouth; and in the iliac passion above mentioned, excrements and clyster are often evacuated by the mouth. See Section XXV. 15. 6. The puncta lacrymalia, with the lacrymal sack and nasal duct, compose a complete gland, and much resemble the intestinal canal: the puncta lacrymalia are absorbent mouths, that take up the tears from the eye, when they have done their office there, and convey them into the nostrils; but when the nasal duct is obstructed, and the lacrymal sack distended with its fluid, on pressure with the finger the mouths of this gland (puncta lacrymalia) will readily disgorge the fluid, they had previously absorbed, back into the eye. 7. As the capillary vessels receive blood from the arteries, and separating the mucus, or perspirable matter from it, convey the remainder back by the veins; these capillary vessels are a set of glands, in every respect similar to the secretory vessels of the liver, or other large congeries of glands. The beginnings of these capillary vessels have frequent anastomoses into each other, in which circumstance they are resembled by the lacteals; and like the mouths or beginnings of other glands, they are a set of absorbent vessels, which drink up the blood which is brought to them by the arteries, as the chyle is drank up by the lacteals: for the circulation of the blood through the capillaries is proved to be independent of arterial impulse; since in the blush of shame, and in partial inflammations, their action is increased, without any increase of the motion of the heart. 8. Yet not only the mouths, or beginnings of these anastomosing capillaries are frequently seen by microscopes, to regurgitate some particles of blood, during the struggles of the animal; but retrograde motion of the blood, in the veins of those animals, from the very heart of the extremity of the limbs, is observable, by intervals, during the distresses of the dying creature. Haller, Elem. Physiol. t. i. p. 216. Now, as the veins have perhaps all of them a valve somewhere between their extremities and the heart, here is ocular demonstration of the fluids in this diseased condition of the animal, repassing through venous valves: and it is hence highly probable, from the strictest analogy, that if the course of the fluids, in the lymphatic vessels, could be subjected to microscopic observation, they would also, in the diseased state of the animal, be seen to repass the valves, and the mouths of those vessels, which had previously absorbed them, or promoted their progression. III. _Communication from the Alimentary Canal to the Bladder, by means of the Absorbent Vessels._ Many medical philosophers, both ancient and modern, have suspected that there was a nearer communication between the stomach and the urinary bladder, than that of the circulation: they were led into this opinion from the great expedition with which cold water, when drank to excess, passes off by the bladder; and from the similarity of the urine, when produced in this hasty manner, with the material that was drank. The former of these circumstances happens perpetually to those who drink abundance of cold water, when they are much heated by exercise, and to many at the beginning of intoxication. Of the latter, many instances are recorded by Etmuller, t. xi. p. 716. where simple water, wine, and wine with sugar, and emulsions, were returned by urine unchanged. There are other experiments, that seem to demonstrate the existence of another passage to the bladder, besides that through the kidneys. Thus Dr. Kratzenstein put ligatures on the ureters of a dog, and then emptied the bladder by a catheter; yet in a little time the dog drank greedily, and made a quantity of water, (Disputat. Morbor. Halleri. t. iv. p. 63.) A similar experiment is related in the Philosophical Transactions, with the same event, (No. 65, 67, for the year 1670.) Add to this, that in some morbid cases the urine has continued to pass, after the suppuration or total destruction of the kidneys; of which many instances are referred to in the Elem. Physiol. t. vii. p. 379. of Dr. Haller. From all which it must be concluded, that some fluids have passed from the stomach or abdomen, without having gone through the sanguiferous circulation: and as the bladder is supplied with many lymphatics, as described by Dr. Watson, in the Philos. Trans. v. 59. p. 392. and as no other vessels open into it besides these and the ureters, it seems evident, that the unnatural urine, produced as above described, when the ureters were tied, or the kidneys obliterated, was carried into the bladder by the retrograde motions of the urinary branch of the lymphatic system. The more certainly to ascertain the existence of another communication between the stomach and bladder, besides that of the circulation, the following experiment was made, to which I must beg your patient attention:--A friend of mine (June 14, 1772) on drinking repeatedly of cold small punch, till he began to be intoxicated, made a quantity of colourless urine. He then drank about two drams of nitre dissolved in some of the punch, and eat about twenty stalks of boiled asparagus: on continuing to drink more of the punch, the next urine that he made was quite clear, and without smell; but in a little time another quantity was made, which was not quite so colourless, and had a strong smell of the asparagus: he then lost about four ounces of blood from the arm. The smell of asparagus was not at all perceptible in the blood, neither when fresh taken, nor the next morning, as myself and two others accurately attended to; yet this smell was strongly perceived in the urine, which was made just before the blood was taken from his arm. Some bibulous paper, moistened in the serum of this blood, and suffered to dry, shewed no signs of nitre by its manner of burning. But some of the same paper, moistened in the urine, and dried, on being ignited, evidently shewed the presence of nitre. This blood and the urine stood some days exposed to the sun in the open air, till they were evaporated to about a fourth of their original quantity, and began to stink: the paper, which was then moistened with the concentrated urine, shewed the presence of much nitre by its manner of burning; whilst that moistened with the blood shewed no such appearance at all. Hence it appears, that certain fluids at the beginning of intoxication, find another passage to the bladder besides the long course of the arterial circulation; and as the intestinal absorbents are joined with the urinary lymphatics by frequent anastomoses, as Hewson has demonstrated; and as there is no other road, we may justly conclude, that these fluids pass into the bladder by the urinary branch of the lymphatics, which has its motions inverted during the diseased state of the animal. A gentleman, who had been some weeks affected with jaundice, and whose urine was in consequence of a very deep yellow, took some cold small punch, in which was dissolved about a dram of nitre; he then took repeated draughts of the punch, and kept himself in a cool room, till on the approach of slight intoxication he made a large quantity of water; this water had a slight yellow tinge, as might be expected from a small admixture of bile secreted from the kidneys; but if the whole of it had passed through the sanguiferous vessels, which were now replete with bile (his whole skin being as yellow as gold) would not this urine also, as well as that he had made for weeks before, have been of a deep yellow? Paper dipped in this water, and dryed, and ignited, shewed evident marks of the presence of nitre, when the flame was blown out. IV. _The Phænomena of the Diabetes explained, and of some Diarrhoeas._ The phenomena of many diseases are only explicable from the retrograde motions of some of the branches of the lymphatic system; as the great and immediate flow of pale urine in the beginning of drunkenness; in hysteric paroxysms; from being exposed to cold air; or to the influence of fear or anxiety. Before we endeavour to illustrate this doctrine, by describing the phænomena of these diseases, we must premise one circumstance; that all the branches of the lymphatic system have a certain sympathy with each other, insomuch that when one branch is stimulated into unusual kinds or quantities of motion, some other branch has its motions either increased, or decreased, or inverted at the same time. This kind of sympathy can only be proved by the concurrent testimony of numerous facts, which will be related in the course of the work. I shall only add here, that it is probable, that this sympathy does not depend on any communication of nervous filaments, but on habit; owing to the various branches of this system having frequently been stimulated into action at the same time. There are a thousand instances of involuntary motions associated in this manner; as in the act of vomiting, while the motions of the stomach and oesophagus are inverted, the pulsations of the arterial system by a certain sympathy become weaker; and when the bowels or kidneys are stimulated by poison, a stone, or inflammation, into more violent action; the stomach and oesophagus by sympathy invert their motions. 1. When any one drinks a moderate quantity of vinous spirit, the whole system acts with more energy by consent with the stomach and intestines, as is seen from the glow on the skin, and the increase of strength and activity; but when a greater quantity of this inebriating material is drank, at the same time that the lacteals are excited into greater action to absorb it; it frequently happens, that the urinary branch of absorbents, which is connected with the lacteals by many anastomoses, inverts its motions, and a great quantity of pale unanimalized urine is discharged. By this wise contrivance too much of an unnecessary fluid is prevented from entering the circulation--This may be called the drunken diabetes, to distinguish it from the other temporary diabetes, which occur in hysteric diseases, and from continued fear or anxiety. 2. If this idle ingurgitation of too much vinous spirit be daily practised, the urinary branch of absorbents at length gains an habit of inverting its motions, whenever the lacteals are much stimulated; and the whole or a great part of the chyle is thus daily carried to the bladder without entering the circulation, and the body becomes emaciated. This is one kind of chronic diabetes, and may be distinguished from the others by the taste and appearance of the urine; which is sweet, and the colour of whey, and may be termed the chyliferous diabetes. 3. Many children have a similar deposition of chyle in their urine, from the irritation of worms in their intestines, which stimulating the mouths of the lacteals into unnatural action, the urinary branch of the absorbents becomes inverted, and carries part of the chyle to the bladder: part of the chyle also has been carried to the iliac and lumbar glands, of which instances are recorded by Haller, t. vii. 225. and which can be explained on no other theory: but the dissections of the lymphatic system of the human body, which have yet been published, are not sufficiently extensive for our purpose; yet if we may reason from comparative anatomy, this translation of chyle to the bladder is much illustrated by the account given of this system of vessels in a turtle, by Mr. Hewson, who observed, "That the lacteals near the root of the mesentery anastomose, so as to form a net-work, from which several large branches go into some considerable lymphatics lying near the spine; and which can be traced almost to the anus, and particularly to the kidneys." Philos. Trans. v. 59. p. 199--Enquiries, p. 74. 4. At the same time that the urinary branch of absorbents, in the beginning of diabetes, is excited into inverted action, the cellular branch is excited by the sympathy above mentioned, into more energetic action; and the fat, that was before deposited, is reabsorbed and thrown into the blood vessels; where it floats, and was mistaken for chyle, till the late experiments of the ingenious Mr. Hewson demonstrated it to be fat. This appearance of what was mistaken for chyle in the blood, which was drawn from these patients, and the obstructed liver, which very frequently accompanies this disease, seems to have led Dr. Mead to suspect the diabetes was owing to a defect of sanguification; and that the schirrosity of the liver was the original cause of it: but as the schirrhus of the liver is most frequently owing to the same causes, that produce the diabetes and dropsies; namely, the great use of fermented liquors; there is no wonder they should exist together, without being the consequence of each other. 5. If the cutaneous branch of absorbents gains a habit of being excited into stronger action, and imbibes greater quantities of moisture from the atmosphere, at the same time that the urinary branch has its motions inverted, another kind of diabetes is formed, which may be termed the aqueous diabetes. In this diabetes the cutaneous absorbents frequently imbibe an amazing quantity of atmospheric moisture; insomuch that there are authentic histories, where many gallons a day, for many weeks together, above the quantity that has been drank, have been discharged by urine. Dr. Keil, in his Medicina Statica, found that he gained eighteen ounces from the moist air of one night; and Dr. Percival affirms, that one of his hands imbibed, after being well chafed, near an ounce and half of water, in a quarter of an hour. (Transact. of the College, London, vol. ii. p. 102.) Home's Medic. Facts, p. 2. sect. 3. The pale urine in hysterical women, or which is produced by fear or anxiety, is a temporary complaint of this kind; and it would in reality be the same disease, if it was confirmed by habit. 6. The purging stools, and pale urine, occasioned by exposing the naked body to cold air, or sprinkling it with cold water, originate from a similar cause; for the mouths of the cutaneous lymphatics being suddenly exposed to cold become torpid, and cease, or nearly cease, to act; whilst, by the sympathy above described, not only the lymphatics of the bladder and intestines cease also to absorb the more aqueous and saline part of the fluids secreted into them; but it is probable that these lymphatics invert their motions, and return the fluids, which were previously absorbed, into the intestines and bladder. At the very instant that the body is exposed naked to the cold air, an unusual movement is felt in the bowels; as is experienced by boys going into the cold bath: this could not occur from an obstruction of the perspirable matter, since there is not time, for that to be returned to the bowels by the course of the circulation. There is also a chronic aqueous diarrhoea, in which the atmospheric moisture, drank up by the cutaneous and pulmonary lymphatics, is poured into the intestines, by the retrograde motions of the lacteals. This disease is most similar to the aqueous diabetes, and is frequently exchanged for it: a distinct instance of this is recorded by Benningerus, Cent. v. Obs. 98. in which an aqueous diarrhoea succeeded an aqueous diabetes, and destroyed the patient. There is a curious example of this, described by Sympson (De Re Medica)--"A young man (says he) was seized with a fever, upon which a diarrhoea came on, with great stupor; and he refused to drink any thing, though he was parched up with excessive heat: the better to supply him with moisture, I directed his feet to be immersed in cold water; immediately I observed a wonderful decrease of water in the vessel, and then an impetuous stream of a fluid, scarcely coloured, was discharged by stool, like a cataract." 7. There is another kind of diarrhoea, which has been called cæliaca; in this disease the chyle, drank up by the lacteals of the small intestines, is probably poured into the large intestines, by the retrograde motions of their lacteals: as in the chyliferous diabetes, the chyle is poured into the bladder, by the retrograde motions of the urinary branch of absorbents. The chyliferous diabetes, like this chyliferous diarrhoea, produces sudden atrophy; since the nourishment, which ought to supply the hourly waste of the body, is expelled by the bladder, or rectum: whilst the aqueous diabetes, and the aqueous diarrhoea produce excessive thirst; because the moisture, which is obtained from the atmosphere, is not conveyed to the thoracic receptacle, as it ought to be, but to the bladder, or lower intestines; whence the chyle, blood, and whole system of glands, are robbed of their proportion of humidity. 8. There is a third species of diabetes, in which the urine is mucilaginous, and appears ropy in pouring it from one vessel into another; and will sometimes coagulate over the fire. This disease appears by intervals, and ceases again, and seems to be occasioned by a previous dropsy in some part of the body. When such a collection is reabsorbed, it is not always returned into the circulation; but the same irritation that stimulates one lymphatic branch to reabsorb the deposited fluid, inverts the urinary branch, and pours it into the bladder. Hence this mucilaginous diabetes is a cure, or the consequence of a cure, of a worse disease, rather than a disease itself. Dr. Cotunnius gave half an ounce of cream of tartar, every morning, to a patient, who had the anasarca; and he voided a great quantity of urine; a part of which, put over the fire, coagulated, on the evaporation of half of it, so as to look like the white of an egg. De Ischiade Nervos. This kind of diabetes frequently precedes a dropsy; and has this remarkable circumstance attending it, that it generally happens in the night; as during the recumbent state of the body, the fluid, that was accumulated in the cellular membrane, or in the lungs, is more readily absorbed, as it is less impeded by its gravity. I have seen more than one instance of this disease. Mr. D. a man in the decline of life, who had long accustomed himself to spirituous liquor, had swelled legs, and other symptoms of approaching anasarca; about once in a week, or ten days, for several months, he was seized, on going to bed, with great general uneasiness, which his attendants resembled to an hysteric fit; and which terminated in a great discharge of viscid urine; his legs became less swelled, and he continued in better health for some days afterwards. I had not the opportunity to try if this urine would coagulate over the fire, when part of it was evaporated, which I imagine would be the criterion of this kind of diabetes; as the mucilaginous fluid deposited in the cells and cysts of the body, which have no communication with the external air, seems to acquire, by stagnation, this property of coagulation by heat, which the secreted mucus of the intestines and bladder do not appear to possess; as I have found by experiment: and if any one should suppose this coagulable urine was separated from the blood by the kidneys, he may recollect, that in the most inflammatory diseases, in which the blood is most replete or most ready to part with the coagulable lymph, none of this appears in the urine. 9. Different kinds of diabetes require different methods of cure. For the first kind, or chyliferous diabetes, after clearing the stomach and intestines, by ipecacuanha and rhubarb, to evacuate any acid material, which may too powerfully stimulate the mouths of the lacteals, repeated and large doses of tincture of cantharides have been much recommended. The specific stimulus of this medicine, on the neck of the bladder, is likely to excite the numerous absorbent vessels, which are spread on that part, into stronger natural actions, and by that means prevent their retrograde ones; till, by persisting in the use of the medicine, their natural habits of motions might again be established. Another indication of cure, requires such medicines, as by lining the intestines with mucilaginous substances, or with such as consist of smooth particles, or which chemically destroy the acrimony of their contents, may prevent the too great action of the intestinal absorbents. For this purpose, I have found the earth precipitated from a solution of alum, by means of fixed alcali, given in the dose of half a dram every six hours, of great advantage, with a few grains of rhubarb, so as to produce a daily evacuation. The food should consist of materials that have the least stimulus, with calcareous water, as of Bristol and Matlock; that the mouths of the lacteals may be as little stimulated as is necessary for their proper absorption; lest with their greater exertions, should be connected by sympathy, the inverted motions of the urinary lymphatics. The same method may be employed with equal advantage in the aqueous diabetes, so great is the sympathy between the skin and the stomach. To which, however, some application to the skin might be usefully added; as rubbing the patient all over with oil, to prevent the too great action of the cutaneous absorbents. I knew an experiment of this kind made upon one patient with apparent advantage. The mucilaginous diabetes will require the same treatment, which is most efficacious in the dropsy, and will be described below. I must add, that the diet and medicines above mentioned, are strongly recommended by various authors, as by Morgan, Willis, Harris, and Etmuller; but more histories of the successful treatment of these diseases are wanting to fully ascertain the most efficacious methods of cure. In a letter from Mr. Charles Darwin, dated April 24, 1778, Edinburgh, is the subsequent passage:--"A man who had long laboured under a diabetes died yesterday in the clinical ward. He had for some time drank four, and passed twelve pounds of fluid daily; each pound of urine contained an ounce of sugar. He took, without considerable relief, gum kino, sanguis diaconis melted with alum, tincture of cantharides, isinglass, gum arabic, crabs eyes, spirit of hartshorn, and eat ten or fifteen oysters thrice a day. Dr. Home, having read my thesis, bled him, and found that neither the fresh blood nor the serum tasted sweet. His body was opened this morning--every viscus appeared in a sound and natural state, except that the left kidney had a very small pelvis, and that there was a considerable enlargement of most of the mesenteric lymphatic glands. I intend to insert this in my thesis, as it coincides with the experiment, where some asparagus was eaten at the beginning of intoxication, and its smell perceived in the urine, though not in the blood." The following case of chyliferous diabetes is extracted from some letters of Mr. Hughes, to whose unremitted care the infirmary at Stafford for many years was much indebted. Dated October 10, 1778. Richard Davis, aged 33, a whitesmith by trade, had drank hard by intervals; was much troubled with sweating of his hands, which incommoded him in his occupation, but which ceased on his frequently dipping them in lime. About seven months ago he began to make large quantities of water; his legs are oedematous, his belly tense, and he complains of a rising in his throat, like the globus hystericus: he eats twice as much as other people, drinks about fourteen pints of small beer a day, besides a pint of ale, some milk-porridge, and a bason of broth, and he makes about eighteen pints of water a day. He tried alum, dragon's blood, steel, blue vitriol, and cantharides in large quantities, and duly repeated, under the care of Dr. Underhill, but without any effect; except that on the day after he omitted the cantharides, he made but twelve pints of water, but on the next day this good effect ceased again. November 21.--He made eighteen pints of water, and he now, at Dr. Darwin's request, took a grain of opium every four hours, and five grains of aloes at night; and had a flannel shirt given him. 22.--Made sixteen pints. 23.--Thirteen pints: drinks less. 24.--Increased the opium to a grain and quarter every four hours: he made twelve pints. 25.--Increased the opium to a grain and half: he now makes ten pints; and drinks eight pints in a day. The opium was gradually increased during the next fortnight, till he took three grains every four hours, but without any further diminution of his water. During the use of the opium he sweat much in the nights, so as to have large drops stand on his face and all over him. The quantity of opium was then gradually decreased, but not totally omitted, as he continued to take about a grain morning and evening. January 17.--He makes fourteen pints of water a day. Dr. Underhill now directed him two scruples of common rosin triturated with as much sugar, every six hours; and three grains of opium every night. 19.--Makes fifteen pints of water: sweats at night. 21.--Makes seventeen pints of water; has twitchings of his limbs in a morning, and pains of his legs: he now takes a dram of rosin for a dose, and continues the opium. 23.--Water more coloured, and reduced to sixteen pints, and he thinks has a brackish taste. 26.--Water reduced to fourteen pints. 28.--Water thirteen pints: he continues the opium, and takes four scruples of the rosin for a dose. February 1.--Water twelve pints. 4.--Water eleven pints: twitchings less; takes five scruples for a dose. 8.--Water ten pints: has had many stools. 12.--Appetite less: purges very much. After this the rosin either purged him, or would not stay on his stomach; and he gradually relapsed nearly to his former condition, and in a few months sunk under the disease. October 3, Mr. Hughes evaporated two quarts of the water, and obtained from it four ounces and half of a hard and brittle saccharine mass, like treacle which had been some time boiled. Four ounces of blood, which he took from his arm with design to examine it, had the common appearances, except that the serum resembled cheese-whey; and that on the evidence of four persons, two of whom did not know what it was they tasted, _the serum had a saltish taste_. From hence it appears, that the saccharine matter, with which the urine of these patients so much abounds, does not enter the blood-vessels like the nitre and asparagus mentioned above; but that the process of digestion resembles the process of the germination of vegetables, or of making barley into malt; as the vast quantity of sugar found in the urine must be made from the food which he took (which was double that taken by others), and from the fourteen pints of small beer which he drank. And, secondly, as the serum of the blood was not sweet, the chyle appears to have been conveyed to the bladder without entering the circulation of the blood, since so large a quantity of sugar, as was found in the urine, namely, twenty ounces a day, could not have previously existed in the blood without being perceptible to the taste. November 1. Mr. Hughes dissolved two drams of nitre in a pint of a decoction of the roots of asparagus, and added to it two ounces of tincture of rhubarb: the patient took a fourth part of this mixture every five minutes, till he had taken the whole.--In about half an hour he made eighteen ounces of water, which was very manifestly tinged with the rhubarb; the smell of asparagus was doubtful. He then lost four ounces of blood, the serum of which was not so opake as that drawn before, but of a yellowish cast, as the serum of the blood usually appears. Paper, dipped three or four times in the tinged urine and dried again, did not scintillate when it was set on fire; but when the flame was blown out, the fire ran along the paper for half an inch; which, when the same paper was unimpregnated, it would not do; nor when the same paper was dipped in urine made before he took the nitre, and dried in the same manner. Paper, dipped in the serum of the blood and dried in the same manner as in the urine, did not scintillate when the flame was blown out, but burnt exactly in the same manner as the same paper dipped in the serum of blood drawn from another person. This experiment, which is copied from a letter of Mr. Hughes, as well as the former, seems to evince the existence of another passage from the intestines to the bladder, in this disease, besides that of the sanguiferous system; and coincides with the curious experiment related in section the third, except that the smell of the asparagus was not here perceived, owing perhaps to the roots having been made use of instead of the heads. The rising in the throat of this patient, and the twitchings of his limbs, seem to indicate some similarity between the diabetes and the hysteric disease, besides the great flow of pale urine, which is common to them both. Perhaps if the mesenteric glands were nicely inspected in the dissections of these patients; and if the thoracic duct, and the larger branches of the lacteals, and if the lymphatics, which arise from the bladder, were well examined by injection, or by the knife, the cause of diabetes might be more certainly understood. The opium alone, and the opium with the rosin, seem much to have served this patient, and might probably have effected a cure, if the disease had been slighter, or the medicine had been exhibited, before it had been confirmed by habit during the seven months it had continued. The increase of the quantity of water on beginning the large doses of rosin was probably owing to his omitting the morning doses of opium. V. _The Phænomena of Dropsies explained._ I. Some inebriates have their paroxysms of inebriety terminated by much pale urine, or profuse sweats, or vomiting, or stools; others have their paroxysms terminated by stupor, or sleep, without the above evacuations. The former kind of these inebriates have been observed to be more liable to diabetes and dropsy; and the latter to gout, gravel, and leprosy. Evoe! attend ye bacchanalians! start at this dark train of evils, and, amid your immodest jests, and idiot laughter, recollect, Quem Deus vult perdere, prius dementat. In those who are subject to diabetes and dropsy, the absorbent vessels are naturally more irritable than in the latter; and by being frequently disturbed or inverted by violent stimulus, and by their too great sympathy with each other, they become at length either entirely paralytic, or are only susceptible of motion from the stimulus of very acrid materials; as every part of the body, after having been used to great irritations, becomes less affected by smaller ones. Thus we cannot distinguish objects in the night, for some time after we come out of a strong light, though the iris is presently dilated; and the air of a summer evening appears cold, after we have been exposed to the heat of the day. There are no cells in the body, where dropsy may not be produced, if the lymphatics cease to absorb that mucilaginous fluid, which is perpetually deposited in them, for the purpose of lubricating their surfaces. If the lymphatic branch, which opens into the cellular membrane, either does its office imperfectly, or not at all; these cells become replete with a mucilaginous fluid, which, after it has stagnated some time in the cells, will coagulate over the fire; and is erroneously called water. Wherever the seat of this disease is, (unless in the lungs or other pendent viscera) the mucilaginous liquid above mentioned will subside to the most depending parts of the body, as the feet and legs, when those are lower than the head and trunk; for all these cells have communications with each other. When the cellular absorbents are become insensible to their usual irritations, it most frequently happens, but not always, that the cutaneous branch of absorbents, which is strictly associated with them, suffers the like inability. And then, as no water is absorbed from the atmosphere, the urine is not only less diluted at the time of its secretion, and consequently in less quantity and higher coloured: but great thirst is at the same time induced, for as no water is absorbed from the atmosphere to dilute the chyle and blood, the lacteals and other absorbent vessels, which have not lost their powers, are excited into more constant or more violent action, to supply this deficiency; whence the urine becomes still less in quantity, and of a deeper colour, and turbid like the yolk of an egg, owing to a greater absorption of its thinner parts. From this stronger action of those absorbents, which still retain their irritability, the fat is also absorbed, and the whole body becomes emaciated. This increased exertion of some branches of the lymphatics, while others are totally or partially paralytic, is resembled by what constantly occurs in the hemiplagia; when the patient has lost the use of the limbs on one side, he is incessantly moving those of the other; for the moving power, not having access to the paralytic limbs, becomes redundant in those which are not diseased. The paucity of urine and thirst cannot be explained from a greater quantity of mucilaginous fluid being deposited in the cellular membrane: for though these symptoms have continued many weeks, or even months, this collection frequently does not amount to more than very few pints. Hence also the difficulty of promoting copious sweats in anasarca is accounted for, as well as the great thirst, paucity of urine, and loss of fat; since, when the cutaneous branch of absorbents is paralytic, or nearly so, there is already too small a quantity of aqueous fluid in the blood: nor can these torpid cutaneous lymphatics be readily excited into retrograde motions. Hence likewise we understand, why in the ascites, and some other dropsies, there is often no thirst, and no paucity of urine; in these cases the cutaneous absorbents continue to do their office. Some have believed, that dropsies were occasioned by the inability of the kidneys, from having only observed the paucity of urine; and have thence laboured much to obtain diuretic medicines; but it is daily observable, that those who die of a total inability to make water, do not become dropsical in consequence of it: Fernelius mentions one, who laboured under a perfect suppression of urine during twenty days before his death, and yet had no symptoms of dropsy. Pathol. 1. vi. c. 8. From the same idea many physicians have restrained their patients from drinking, though their thirst has been very urgent; and some cases have been published, where this cruel regimen has been thought advantageous: but others of nicer observation are of opinion, that it has always aggravated the distresses of the patient; and though it has abated his swellings, yet by inducing a fever it has hastened his dissolution. See Transactions of the College, London, vol. ii. p. 235. Cases of Dropsy by Dr. G. Baker. The cure of anasarca, so far as respects the evacuation of the accumulated fluid, coincides with the idea of the retrograde action of the lymphatic system. It is well known that vomits, and other drugs, which induce sickness or nausea; at the same time that they evacuate the stomach, produce a great absorption of the lymph accumulated in the cellular membrane. In the operation of a vomit, not only the motions of the stomach and duodenum become inverted, but also those of the lymphatics and lacteals, which belong to them; whence a great quantity of chyle and lymph is perpetually poured into the stomach and intestines, during the operation, and evacuated by the mouth. Now at the same time, other branches of the lymphatic system, viz. those which open on the cellular membrane, are brought into more energetic action, by the sympathy above mentioned, and an increase of their absorption is produced. Hence repeated vomits, and cupreous salts, and small doses of squill or foxglove, are so efficacious in this disease. And as drastic purges act also by inverting the motions of the lacteals; and thence the other branches of lymphatics are induced into more powerful natural action, by sympathy, and drink up the fluids from all the cells of the body; and by their anastomoses, pour them into the lacteal branches; which, by their inverted actions, return them into the intestines; and they are thus evacuated from the body:--these purges also are used with success in discharging the accumulated fluid in anasarca. II. The following cases are related with design to ascertain the particular kinds of dropsy in which the digitalis purpurea, or common foxglove, is preferable to squill, or other evacuants, and were first published in 1780, in a pamphlet entitled Experiments on mucilaginous and purulent Matter, &c. Cadell. London. Other cases of dropsy, treated with digitalis, were afterwards published by Dr. Darwin in the Medical Transactions, vol. iii. in which there is a mistake in respect to the dose of the powder of foxglove, which should have been from five grains to one, instead of from five grains to ten. _Anasarca of the Lungs._ 1. A lady, between forty and fifty years of age, had been indisposed some time, was then seized with cough and fever, and afterwards expectorated much digested mucus. This expectoration suddenly ceased, and a considerable difficulty of breathing supervened, with a pulse very irregular both in velocity and strength; she was much distressed at first lying down, and at first rising; but after a minute or two bore either of those attitudes with ease. She had no pain or numbness in her arms; she had no hectic fever, nor any cold shiverings, and the urine was in due quantity, and of the natural colour. The difficulty of breathing was twice considerably relieved by small doses of ipecacuanha, which operated upwards and downwards, but recurred in a few days: she was then directed a decoction of foxglove, (digitalis purpurea) prepared by boiling four ounces of the fresh leaves from two pints of water to one pint; to which was added two ounces of vinous spirit: she took three large spoonfuls of this mixture every two hours, till she had taken it four times; a continued sickness supervened, with frequent vomiting, and a copious flow of urine: these evacuations continued at intervals for two or three days, and relieved the difficulty of breathing--She had some relapses afterwards, which were again relieved by the repetition of the decoction of foxglove. 2. A gentleman, about sixty years of age, who had been addicted to an immoderate use of fermented liquors, and had been very corpulent, gradually lost his strength and flesh, had great difficulty of breathing, with legs somewhat swelled, and a very irregular pulse. He was very much distressed at first lying down, and at first rising from his bed, yet in a minute or two was easy in both those attitudes. He made straw-coloured urine in due quantity, and had no pain or numbness of his arms. He took a large spoonful of the decoction of foxglove, as above, every hour, for ten or twelve successive hours, had incessant sickness for about two days, and passed a large quantity of urine; upon which his breath became quite easy, and the swelling of his legs subsided; but as his whole constitution was already sinking from the previous intemperance of his life, he did not survive more than three or four months. _Hydrops Pericardii._ 3. A gentleman of temperate life and sedulous application to business, between thirty and forty years of age, had long been subject, at intervals, to an irregular pulse: a few months ago he became weak, with difficulty of breathing, and dry cough. In this situation a physician of eminence directed him to abstain from all animal food and fermented liquor, during which regimen all his complaints increased; he now became emaciated, and totally lost his appetite; his pulse very irregular both in velocity and strength; with great difficulty of breathing, and some swelling of his legs; yet he could lie down horizontally in his bed, though he got little sleep, and passed a due quantity of urine, and of the natural colour: no fullness or hardness could be perceived about the region of the liver; and he had no pain or numbness in his arms. One night he had a most profuse sweat all over his body and limbs, which quite deluged his bed, and for a day or two somewhat relieved his difficulty of breathing, and his pulse became less irregular: this copious sweat recurred three or four times at the intervals of five or six days, and repeatedly alleviated his symptoms. He was directed one large spoonful of the above decoction of foxglove every hour, till it procured some considerable evacuation: after he had taken it eleven successive hours he had a few liquid stools, attended with a great flow of urine, which last had a dark tinge, as if mixed with a few drops of blood: he continued sick at intervals for two days, but his breath became quite easy, and his pulse quite regular, the swelling of his legs disappeared, and his appetite and sleep returned. He then took three grains of white vitriol twice a day, with some bitter medicines, and a grain of opium with five grains of rhubarb every night; was advised to eat flesh meat, and spice, as his stomach would bear it, with small beer, and a few glasses of wine; and had issues made in his thighs; and has suffered no relapse. 4. A lady, about fifty years of age, had for some weeks great difficulty of breathing, with very irregular pulse, and considerable general debility: she could lie down in bed, and the urine was in due quantity and of the natural colour, and she had no pain or numbness of her arms. She took one large spoonful of the above decoction of foxglove every hour, for ten or twelve successive hours; was sick, and made a quantity of pale urine for about two days, and was quite relieved both of the difficulty of breathing, and the irregularity of her pulse. She then took a grain of opium, and five grains of rhubarb, every night, night, for many weeks; with some slight chalybeate and bitter medicines, and has suffered no relapse. _Hydrops Thoracis._ 5. A tradesman, about fifty years of age, became weak and short of breath, especially on increase of motion, with pain in one arm, about the insertion of the biceps muscle. He observed he sometimes in the night made an unusual quantity of pale water. He took calomel, alum, and peruvian bark, and all his symptoms increased: his legs began to swell considerably; his breath became more difficult, and he could not lie down in bed; but all this time he made a due quantity of straw-coloured water. The decoction of foxglove was given as in the preceding cases, which operated chiefly by purging, and seemed to relieve his breath for a day or two; but also seemed to contribute to weaken him.--He became after some weeks universally dropsical, and died comatous. 6. A young lady of delicate constitution, with light eyes and hair, and who had perhaps lived too abstemiously both in respect to the quantity and quality of what she eat and drank, was seized with great difficulty of breathing, so as to threaten immediate death. Her extremities were quite cold, and her breath felt cold to the back of one's hand. She had no sweat, nor could be down for a single moment; and had previously, and at present, complained of great weakness and pain and numbness of both her arms; had no swelling of her legs, no thirst, water in due quantity and colour. Her sister, about a year before, was afflicted with similar symptoms, was repeatedly blooded, and died universally dropsical. A grain of opium was given immediately, and repeated every six hours with evident and amazing advantage; afterwards a blister, with chalybeates, bitters, and essential oils, were exhibited, but nothing had such eminent effect in relieving the difficulty of breathing and coldness of her extremities as opium, by the use of which in a few weeks she perfectly regained her health, and has suffered no relapse. _Ascites._ 7. A young lady of delicate constitution having been exposed to great fear, cold, and fatigue, by the overturn of a chaise in the night, began with pain and tumour in the right hypochondrium: in a few months a fluctuation was felt throughout the whole abdomen, more distinctly perceptible indeed about the region of the stomach; since the integuments of the lower part of the abdomen generally become thickened in this disease by a degree of anasarca. Her legs were not swelled, no thirst, water in due quantity and colour.--She took the foxglove so as to induce sickness and stools, but without abating the swelling, and was obliged at length to submit to the operation of tapping. 8. A man about sixty-seven, who had long been accustomed to spirituous potation, had some time laboured under ascites; his legs somewhat swelled; his breath easy in all attitudes; no appetite; great thirst; urine in exceedingly small quantity, very deep coloured, and turbid; pulse equal. He took the foxglove in such quantity as vomited him, and induced sickness for two days; but procured no flow of urine, or diminution of his swelling; but was thought to leave him considerably weaker. 9. A corpulent man, accustomed to large potation of fermented liquors, had vehement cough, difficult breathing, anasarca of his legs, thighs, and hands, and considerable tumour, with evident fluctuation of his abdomen; his pulse was equal; his urine in small quantity, of deep colour, and turbid. These swellings had been twice considerably abated by drastic cathartics. He took three ounces of a decoction of foxglove (made by boiling one ounce of the fresh leaves in a pint of water) every three hours, for two whole days; it then began to vomit and purge him violently, and promoted a great flow of urine; he was by these evacuations completely emptied in twelve hours. After two or three months all these symptoms returned, and were again relieved by the use of the foxglove; and thus in the space of about three years he was about ten times evacuated, and continued all that time his usual potations: excepting at first, the medicine operated only by urine, and did not appear considerably to weaken him--The last time he took it, it had no effect; and a few weeks afterwards he vomited a great quantity of blood, and expired. QUERIES. 1. As the first six of these patients had a due discharge of urine, and of the natural colour, was not the feat of the disease confined to some part of the thorax, and the swelling of the legs rather a symptom of the obstructed circulation of the blood, than of a paralysis of the cellular lymphatics of those parts? 2. When the original disease is a general anasarca, do not the cutaneous lymphatics always become paralytic at the same time with the cellular ones, by their greater sympathy with each other? and hence the paucity of urine, and the great thirst, distinguish this kind of dropsy? 3. In the anasarca of the lungs, when the disease is not very great, though the patients have considerable difficulty of breathing at their first lying down, yet after a minute or two their breath becomes easy again; and the same occurs at their first rising. Is not this owing to the time necessary for the fluid in the cells of the lungs to change its place, so as the least to incommode respiration in the new attitude? 4. In the dropsy of the pericardium does not the patient bear the horizontal or perpendicular attitude with equal ease? Does this circumstance distinguish the dropsy of the pericardium from that of the lungs and of the thorax? 5. Do the universal sweats distinguish the dropsy of the pericardium, or of the thorax? and those, which cover the upper parts of the body only, the anasarca of the lungs? 6. When in the dropsy of the thorax, the patient endeavours to lie down, does not the extravasated fluid compress the upper parts of the bronchia, and totally preclude the access of air to every part of the lungs; whilst in the perpendicular attitude the inferior parts of the lungs only are compressed? Does not something similar to this occur in the anasarca of the lungs, when the disease is very great, and thus prevent those patients also from lying down? 7. As a principal branch of the fourth cervical nerve of the left side, after having joined a branch of the third and of the second cervical nerves, descending between the subclavian vein and artery, is received in a groove formed for it in the pericardium, and is obliged to make a considerable turn outwards to go over the prominent part of it, where the point of the heart is lodged, in its course to the diaphragm; and as the other phrenic nerve of the right side has a straight course to the diaphragm; and as many other considerable branches of this fourth pair of cervical nerves are spread on the arms; does not a pain in the left arm distinguish a disease of the pericardium, as in the angina pectoris, or in the dropsy of the pericardium? and does not a pain or weakness in both arms distinguish the dropsy of the thorax? 8. Do not the dropsies of the thorax and pericardium frequently exist together, and thus add to the uncertainty and fatality of the disease? 9. Might not the foxglove be serviceable in hydrocephalus internus, in hydrocele, and in white swellings of the joints? VI. _Of cold Sweats._ There have been histories given of chronical immoderate sweatings, which bear some analogy to the diabetes. Dr. Willis mentions a lady then living, whose sweats where for many years so profuse, that all her bed-clothes were not only moistened, but deluged with them every night; and that many ounces, and sometimes pints, of this sweat, were received in vessels properly placed, as it trickled down her body. He adds, that she had great thirst, had taken many medicines, and submitted to various rules of life, and changes of climate, but still continued to have these immoderate sweats. Pharmac. ration. de sudore anglico. Dr. Willis has also observed, that the sudor anglicanus which appeared in England, in 1483, and continued till 1551, was in some respects similar to the diabetes; and as Dr. Caius, who saw this disease, mentions the viscidity, as well as the quantity of these sweats, and adds, that the extremities were often cold, when the internal parts were burnt up with heat and thirst, with great and speedy emaciation and debility: there is great reason to believe, that the fluids were absorbed from the cells of the body by the cellular and cystic branches of the lymphatics, and poured on the skin by the retrograde motions of the cutaneous ones. Sydenham has recorded, in the stationary fever of the year 1685, the viscid sweats flowing from the head, which were probably from the same source as those in the sweating plague above mentioned. It is very common in dropsies of the chest or lungs to have the difficulty of breathing relieved by copious sweats, flowing from the head and neck. Mr. P. about 50 years of age, had for many weeks been afflicted with anasarca of his legs and thighs, attended with difficulty of breathing; and had repeatedly been relieved by squill, other bitters, and chalybeates.--One night the difficulty of breathing became so great, that it was thought he must have expired; but so copious a sweat came out of his head and neck, that in a few hours some pints, by estimation, were wiped off from those parts, and his breath was for a time relieved. This dyspnoea and these sweats recurred at intervals, and after some weeks he ceased to exist. The skin of his head and neck felt cold to the hand, and appeared pale at the time these sweats flowed so abundantly; which is a proof, that they were produced by an inverted motion of the absorbents of those parts: for sweats, which are the consequence of an increased action of the sanguiferous system, are always attended with a warmth of the skin, greater than is natural, and a more florid colour; as the sweats from exercise, or those that succeed the cold fits of agues. Can any one explain how these partial sweats should relieve the difficulty of breathing in anasarca, but by supposing that the pulmonary branch of absorbents drank up the fluid in the cavity of the thorax, or in the cells of the lungs, and threw it on the skin, by the retrograde motions of the cutaneous branch? for, if we could suppose, that the increased action of the cutaneous glands or capillaries poured upon the skin this fluid, previously absorbed from the lungs; why is not the whole surface of the body covered with sweat? why is not the skin warm? Add to this, that the sweats above mentioned were clammy or glutinous, which the condensed perspirable matter is not; whence it would seem to have been a different fluid from that of common perspiration. Dr. Dobson, of Liverpool, has given a very ingenious explanation of the acid sweats, which he observed in a diabetic patient--he thinks part of the chyle is secreted by the skin, and afterwards undergoes an acetous fermentation.--Can the chyle get thither, but by an inverted motion of the cutaneous lymphatics? in the same manner as it is carried to the bladder, by the inverted motions of the urinary lymphatics. Medic. Observat. and Enq. London, vol. v. Are not the cold sweats in some fainting fits, and in dying people, owing to an inverted motion of the cutaneous lymphatics? for in these there can be no increased arterial or glandular action. Is the difficulty of breathing, arising from anasarca of the lungs, relieved by sweats from the head and neck; whilst that difficulty of breathing, which arises from a dropsy of the thorax, or pericardium, is never attended with these sweats of the head? and thence can these diseases be distinguished from each other? Do the periodic returns of nocturnal asthma rise from a temporary dropsy of the lungs, collected during their more torpid state in sound deep, and then re-absorbed by the vehement efforts of the disordered organs of respiration, and carried off by the copious sweats about the head and neck? More extensive and accurate dissections of the lymphatic system are wanting to enable us to unravel these knots of science. VII. _Translations of Matter, of Chyle, of Milk, of Urine. Operation of purging Drugs applied externally._ 1. The translations of matter from one part of the body to another, can only receive an explanation from the doctrine of the occasional retrograde motions of some branches of the lymphatic system: for how can matter, absorbed and mixed with the whole mass of blood, be so hastily collected again in any one part? and is it not an immutable law, in animal bodies, that each gland can secrete no other, but its own proper fluid? which is, in part, fabricated in the very gland by an animal process, which it there undergoes: of these purulent translations innumerable and very remarkable instances are recorded. 2. The chyle, which is seen among the materials thrown up by violent vomiting, or in purging stools, can only come thither by its having been poured into the bowels by the inverted motions of the lacteals: for our aliment is not converted into chyle in the stomach or intestines by a chemical process, but is made in the very mouths of the lacteals; or in the mesenteric glands; in the same manner as other secreted fluids are made by an animal process in their adapted glands. Here a curious phænomenon in the exhibition of mercury is worth explaining:--If a moderate dose of calomel, as six or ten grains, be swallowed, and within one or two days a cathartic is given, a salivation is prevented: but after three or four days, a salivation having come on, repeated purges every day, for a week or two, are required to eliminate the mercury from the constitution. For this acrid metallic preparation, being absorbed by the mouth of the lacteals, continues, for a time arrested by the mesenteric glands, (as the variolous or venereal poisons swell the subaxillar or inguinal glands): which, during the operation of a cathartic, is returned into the intestines by the inverted action of the lacteals, and thus carried out of the system. Hence we understand the use of vomits or purges, to those who have swallowed either contagious or poisonous materials, even though exhibited a day or even two days after such accidents; namely, that by the retrograde motions of the lacteals and lymphatics, the material still arrested in the mesenteric, or other glands, may be eliminated from the body. 3. Many instances of milk and chyle found in ulcers are given by Haller, El. Physiol. t. vii. p. 12, 23, which admit of no other explanation than by supposing, that the chyle, imbibed by one branch of the absorbent system, was carried to the ulcer, by the inverted motions of another branch of the same system. 4. Mrs. P. on the second day after delivery, was seized with a violent purging, in which, though opiates, mucilages, the bark, and testacea were profusely used, continued many days, till at length she recovered. During the time of this purging, no milk could be drawn from her breasts; but the stools appeared like the curd of milk broken into small pieces. In this case, was not the milk taken up from the follicles of the pectoral glands, and thrown on the intestines, by a retrogression of the intestinal absorbents? for how can we for a moment suspect that the mucous glands of the intestines could separate pure milk from the blood? Doctor Smelly has observed, that loose stools, mixed with milk, which is curdled in the intestines, frequently relieves the turgescency of the breasts of those who studiously repel their milk. Cases in Midwifery, 43, No. 2. 1. 5. J.F. Meckel observed in a patient, whose urine was in small quantity and high coloured, that a copious sweat under the arm-pits, of a perfectly urinous smell, stained the linen; which ceased again when the usual quantity of urine was discharged by the urethra. Here we must believe from analogy, that the urine was first secreted in the kidneys, then re-absorbed by the increased action of the urinary lymphatics, and lastly carried to the axillae by the retrograde motions of the lymphatic branches of those parts. As in the jaundice it is necessary, that the bile should first be secreted by the liver, and re-absorbed into the circulation, to produce the yellowness of the skin; as was formerly demonstrated by the late Dr. Munro, (Edin. Medical Essays) and if in this patient the urine had been re-absorbed into the mass of blood, as the bile in the jaundice, why was it not detected in other parts of the body, as well as in the arm-pits? 6. Cathartic and vermifuge medicines applied externally to the abdomen, seem to be taken up by the cutaneous branch of lymphatics, and poured on the intestines by the retrograde motions of the lacteals, without having passed the circulation. For when the drastic purges are taken by the mouth, they excite the lacteals of the intestines into retrograde motions, as appears from the chyle, which is found coagulated among the fæces, as was shewn above, (sect. 2 and 4.) And as the cutaneous lymphatics are joined with the lacteals of the intestines, by frequent anastomoses; it would be more extraordinary, when a strong purging drug, absorbed by the skin, is carried to the anastomosing branches of the lacteals unchanged, if it should not excite them into retrograde action as efficaciously, as if it was taken by the mouth, and mixed with the food of the stomach. VIII. _Circumstances by which the Fluids, that are effused by the retrograde Motions of the absorbent Vessels, are distinguished._ 1. We frequently observe an unusual quantity of mucus or other fluids in some diseases, although the action of the glands, by which those fluids are separated from the blood, is not unusually increased; but when the power of absorption alone is diminished. Thus the catarrhal humour from the nostrils of some, who ride in frosty weather; and the tears, which run down the cheeks of those, who have an obstruction of the puncta lacrymalia; and the ichor of those phagedenic ulcers, which are not attended with inflammation, are all instances of this circumstance. These fluids however are easily distinguished from others by their abounding in ammoniacal or muriatic salts; whence they inflame the circumjacent skin: thus in the catarrh the upper lip becomes red and swelled from the acrimony of the mucus, and patients complain of the saltness of its taste. The eyes and cheeks are red with the corrosive tears, and the ichor of some herpetic eruptions erodes far and wide the contiguous parts, and is pungently salt to the taste, as some patients have informed me. Whilst, on the contrary, those fluids, which are effused by the retrograde action of the lymphatics, are for the most part mild and innocent; as water, chyle, and the natural mucus: or they take their properties from the materials previously absorbed, as in the coloured or vinous urine, or that scented with asparagus, described before. 2. Whenever the secretion of any fluid is increased, there is at the same time an increased heat in the part; for the secreted fluid, as the bile, did not previously exist in the mass of blood, but a new combination is produced in the gland. Now as solutions are attended with cold, so combinations are attended with heat; and it is probable the sum of the heat given out by all the secreted fluids of animal bodies may be the cause of their general heat above that of the atmosphere. Hence the fluids derived from increased secretions are readily distinguished from those originating from the retrograde motions of the lymphatics: thus an increase of heat either in the diseased parts, or diffused over the whole body, is perceptible, when copious bilious stools are consequent to an inflamed liver; or a copious mucous salivation from the inflammatory angina. 3. When any secreted fluid is produced in an unusual quantity, and at the same time the power of absorption is increased in equal proportion, not only the heat of the gland becomes more intense, but the secreted fluid becomes thicker and milder, its thinner and saline parts being re-absorbed: and these are distinguishable both by their greater consistence, and by their heat, from the fluids, which are effused by the retrograde motions of the lymphatics; as is observable towards the termination of gonorrhoea, catarrh, chincough, and in those ulcers, which are said to abound with laudable pus. 4. When chyle is observed in stools, or among the materials ejected by vomit, we may be confident it must have been brought thither by the retrograde motions of the lacteals; for chyle does not previously exist amid the contents of the intestines, but is made in the very mouths of the lacteals, as was before explained. 5. When chyle, milk, or other extraneous fluids are found in the urinary bladder, or in any other excretory receptacle of a gland; no one can for a moment believe, that these have been collected from the mass of blood by a morbid secretion, as it contradicts all analogy. ---- Aurea duræ Mala ferant quercus? Narcisco floreat alnus? Pinguia corticibus sudent electra myricæ?--VIRGIL. IX. _Retrograde Motions of Vegetable juices._ There are besides some motions of the sap in vegetables, which bear analogy to our present subject; and as the vegetable tribes are by many philosophers held to be inferior animals, it may be a matter of curiosity at least to observe, that their absorbent vessels seem evidently, at times, to be capable of a retrograde motion. Mr. Perault cut off a forked branch of a tree, with the leaves on; and inverting one of the forks into a vessel of water, observed, that the leaves on the other branch continued green much longer than those of a similar branch, cut off from the same tree; which shews, that the water from the vessel was carried up one part of the forked branch, by the retrograde motion of its vessels, and supplied nutriment some time to the other part of the branch, which was out of the water. And the celebrated Dr. Hales found, by numerous very accurate experiments, that the sap of trees rose upwards during the warmer hours of the day, and in part descended again during the cooler ones. Vegetable Statics. It is well known that the branches of willows, and of many other trees, will either take root in the earth or engraft on other trees, so as to have their natural direction inverted, and yet flourish with vigour. Dr. Hope has also made this pleasing experiment, after the manner of Hales--he has placed a forked branch, cut from one tree, erect between two others; then cutting off a part of the bark from one fork applied it to a similar branch of one of the trees in its vicinity; and the same of the other fork; so that a tree is seen to grow suspended in the air, between two other trees; which supply their softer friend with due nourishment. Miranturque novas frondes, et non sua poma. All these experiments clearly evince, that the juices of vegetables can occasionally pass either upwards or downwards in their absorbent system of vessels. X. _Objections answered._ The following experiment, at first view, would seem to invalidate this opinion of the retrograde motions of the lymphatic vessels, in some diseases. About a gallon of milk having been giving to an hungry swine, he was suffered to live about an hour, and was then killed by a stroke or two on his head with an axe.--On opening his belly the lacteals were well seen filled with chyle; on irritating many of the branches of them with a knife, they did not appear to empty themselves hastily; but they did however carry forwards their contents in a little time. I then passed a ligature round several branches of lacteals, and irritated them much with a knife beneath the ligature, but could not make them regurgitate their contained fluid into the bowels. I am not indeed certain, that the nerve was not at the same time included in the ligature, and thus the lymphatic rendered unirritable or lifeless; but this however is certain, that it is not any quantity of any stimulus, which induces the vessels of animal bodies to revert their motions; but a certain quantity of a certain stimulus, as appears from wounds in the stomach, which do not produce vomiting; and wounds of the intestines, which do not produce the cholera morbus. At Nottingham, a few years ago, two shoemakers quarrelled, and one of them with a knife, which they use in their occupation, stabbed his companion about the region of the stomach. On opening the abdomen of the wounded man after his death the food and medicines he had taken were in part found in the cavity of the belly, on the outside of the bowels; and there was a wound about half an inch long at the bottom of the stomach; which I suppose was distended with liquor and food at the time of the accident; and thence was more liable to be injured at its bottom: but during the whole time he lived, which was about ten days, he had no efforts to vomit, nor ever even complained of being sick at the stomach! Other cases similar to this are mentioned in the philosophical transactions. Thus, if you vellicate the throat with a feather, nausea is produced; if you wound it with a penknife, pain is induced, but not sickness. So if the soles of the feet of children or their armpits are tickled, convulsive laughter is excited, which ceases the moment the hand is applied, so as to rub them more forcibly. The experiment therefore above related upon the lacteals of a dead pig, which were included in a strict ligature, proves nothing; as it is not the quantity, but the kind of stimulus, which excites the lymphatic vessels into retrograde motion. XI. _The Causes which induce the retrograde Motions of animal Vessels; and the Medicines by which the natural Motions are restored._ 1. Such is the construction of animal bodies, that all their parts, which are subjected to less stimuli than nature designed, perform their functions with less accuracy: thus, when too watery or too acescent food is taken into the stomach, indigestion, and flatulency, and heartburn succeed. 2. Another law of irritation, connate with our existence, is, that all those parts of the body, which have previously been exposed to too great a quantity of such stimuli, as strongly affect them, become for some time afterwards disobedient to the natural quantity of their adapted stimuli.--Thus the eye is incapable of seeing objects in an obscure room, though the iris is quite dilated, after having been exposed to the meridian sun. 3. There is a third law of irritation, that all the parts of our bodies, which have been lately subjected to less stimulus, than they have been accustomed to, when they are exposed to their usual quantity of stimulus, are excited into more energetic motions: thus when we come from a dusky cavern into the glare of daylight, our eyes are dazzled; and after emerging from the cold bath, the skin becomes warm and red. 4. There is a fourth law of irritation, that all the parts of our bodies, which are subjected to still stronger stimuli for a length of time, become torpid, and refuse to obey even these stronger stimuli; and thence do their offices very imperfectly.--Thus, if any one looks earnestly for some minutes on an area, an inch diameter, of red silk, placed on a sheet of white paper, the image of the silk will gradually become pale, and at length totally vanish. 5. Nor is it the nerves of sense alone, as the optic and auditory nerves, that thus become torpid, when the stimulus is withdrawn or their irritability decreased; but the motive muscles, when they are deprived of their natural stimuli, or of their irritability, become torpid and paralytic; as is seen in the tremulous hand of the drunkard in a morning; and in the awkward step of age. The hollow muscles also, of which the various vessels of the body are constructed, when they are deprived of their natural stimuli, or of their due degree of irritability, not only become tremulous, as the arterial pulsations of dying people; but also frequently invert their motions, as in vomiting, in hysteric suffocations, and diabetes above described. I must beg your patient attention, for a few moments whilst I endeavour to explain, how the retrograde actions of our hollow muscles are the consequence of their debility; as the tremulous actions of the solid muscles are the consequence of their debility. When, through fatigue, a muscle can act no longer; the antagonist muscles, either by their inanimate elasticity, or by their animal action, draw the limb into a contrary direction: in the solid muscles, as those of locomotion, their actions are associated in tribes, which have been accustomed to synchronous action only; hence when they are fatigued, only a single contrary effort takes place; which is either tremulous, when the fatigued muscles are again immediately brought into action; or it is a pandiculation, or stretching, where they are not immediately again brought into action. Now the motions of the hollow muscles, as they in general propel a fluid along their cavities, are associated in trains, which have been accustomed to successive actions: hence when one ring of such a muscle is fatigued from its too great debility, and is brought into retrograde action, the next ring from its association falls successively into retrograde action; and so on throughout the whole canal. See Sect. XXV. 6. 6. But as the retrograde motions of the stomach, oesophagus, and fauces in vomiting are, as it were, apparent to the eye; we shall consider this operation more minutely, that the similar operations in the more recondite parts of our system may be easier understood. From certain nauseous ideas of the mind, from an ungrateful taste in the mouth, or from foetid smells, vomiting is sometimes instantly excited; or even from a stroke on the head, or from the vibratory motions of a ship; all which originate from association, or sympathy. See Sect. XX. on Vertigo. But when the stomach is subjected to a less stimulus than is natural, according to the first law of irritation mentioned above, its motions become disturbed, as in hunger; first pain is produced, then sickness, and at length vain efforts to vomit, as many authors inform us. But when a great quantity of wine, or of opium, is swallowed, the retrograde motions of the stomach do not occur till after several minutes, or even hours; for when the power of so strong a stimulus ceases, according to the second law of irritation, mentioned above, the peristaltic motions become tremulous, and at length retrograde; as is well known to the drunkard, who on the next morning has sickness and vomitings. When a still greater quantity of wine, or of opium, or when nauseous vegetables, or strong bitters, or metallic salts, are taken into the stomach, they quickly induce vomiting; though all these in less doses excite the stomach into more energetic action, and strengthen the digestion; as the flowers of chamomile, and the vitriol of zinc: for, according to the fourth law of irritation, the stomach will not long be obedient to a stimulus so much greater than is natural; but its action becomes first tremulous and then retrograde. 7. When the motions of any vessels become retrograde, less heat of the body is produced; for in paroxysms of vomiting, of hysteric affections, of diabetes, of asthma, the extremities of the body are cold: hence we may conclude, that these symptoms arise from the debility of the parts in action; for an increase of muscular action is always attended with increase of heat. 8. But as animal debility is owing to defect of stimulus, or to defect of irritability, as shewn above, the method of cure is easily deduced: when the vascular muscles are not excited into their due action by the natural stimuli, we should exhibit those medicines, which possess a still greater degree of stimulus; amongst these are the foetids, the volatiles, aromatics, bitters, metallic salts, opiates, wine, which indeed should be given in small doses, and frequently repeated. To these should be added constant, but moderate exercise, cheerfulness of mind, and change of country to a warmer climate; and perhaps occasionally the external stimulus of blisters. It is also frequently useful to diminish the quantity of natural stimulus for a short time, by which afterwards the irritability of the system becomes increased; according to the third law of irritation above-mentioned, hence the use of baths somewhat colder than animal heat, and of equitation in the open air. _The catalogue of diseases owing to the retrograde motions of lymphatics is here omitted, as it will appear in the second volume of this work. The following is the conclusion to this thesis of_ Mr. CHARLES DARWIN. Thus have I endeavoured in a concise manner to explain the numerous diseases, which deduce their origin from the inverted motions of the hollow muscles of our bodies: and it is probable, that Saint Vitus's dance, and the stammering of speech, originate from a similar, inverted order of the associated motions of some of the solid muscles; which, as it is foreign to my present purpose, I shall not here discuss. I beg, illustrious professors, and ingenious fellow-students, that you will recollect how difficult a talk I have attempted, to evince the retrograde motions of the lymphatic vessels, when the vessels themselves for so many ages escaped the eyes and glasses of philosophers: and if you are not yet convinced of the truth of this theory, hold, I entreat you, your minds in suspense, till ANATOMY draws her sword with happier omens, cuts asunder the knots, which entangle PHYSIOLOGY; and, like an augur inspecting the immolated victim, announces to mankind the wisdom of HEAVEN. * * * * * SECT. XXX. PARALYSIS OF THE LIVER AND KIDNEYS. I. 1._Bile-ducts less irritable after having been stimulated much._ 2. _Jaundice from paralysis of the bile-ducts cured by electric shocks._ 3. _From bile-stones. Experiments on bile-stones. Oil vomit._ 4. _Palsy of the liver, two cases._ 5. _Schirrosity of the liver._ 6. _Large livers of geese._ II. _Paralysis of the kidneys._ III. _Story of Prometheus._ I. 1. From the ingurgitation of spirituous liquors into the stomach and duodenum, the termination of the common bile-duct in that bowel becomes stimulated into unnatural action, and a greater quantity of bile is produced from all the secretory vessels of the liver, by the association of their motions with those of their excretory ducts; as has been explained in Section XXIV. and XXV. but as all parts of the body, that have been affected with stronger stimuli for any length of time, become less susceptible of motion, from their natural weaker stimuli, it follows, that the motions of the secretory vessels, and in consequence the secretion of bile, is less than is natural during the intervals of sobriety. 2. If this ingurgitation of spirituous liquors has been daily continued in considerable quantity, and is then suddenly intermitted, a languor or paralysis of the common bile-duct is induced; the bile is prevented from being poured into the intestines; and as the bilious absorbents are stimulated into stronger action by its accumulation, and by the acrimony or viscidity, which it acquires by delay, it is absorbed, and carried to the receptacle of the chyle; or otherwise the secretory vessels of the liver, by the above-mentioned stimulus, invert their motions, and regurgitate their contents into the blood, as sometimes happens to the tears in the lachrymal sack, see Sect. XXIV. 2. 7. and one kind of jaundice is brought on. There is reason to believe, that the bile is most frequently returned into the circulation by the inverted motions of these hepatic glands, for the bile does not seem liable to be absorbed by the lymphatics, for it soaks through the gall-ducts, and is frequently found in the cellular membrane. This kind of jaundice is not generally attended with pain, neither at the extremity of the bile-duct, where it enters the duodenum, nor on the region of the gall-bladder. Mr. S. a gentleman between 40 and 50 years of age, had had the jaundice about six weeks, without pain, sickness, or fever; and had taken emetics, cathartics, mercurials, bitters, chalybeates, essential oil, and ether, without apparent advantage. On a supposition that the obstruction of the bile might be owing to the paralysis, or torpid action of the common bile-duct, and the stimulants taken into the stomach seeming to have no effect, I directed half a score smart electric shocks from a coated bottle, which held about a quart, to be passed through the liver, and along the course of the common gall-duct, as near as could be guessed, and on that very day the stools became yellow; he continued the electric shocks a few days more, and his skin gradually became clear. 3. The bilious vomiting and purging, that affects some people by intervals of a few weeks, is a less degree of this disease; the bile-duct is less irritable than natural, and hence the bile becomes accumulated in the gall-bladder, and hepatic ducts, till by its quantity, acrimony or viscidity, a greater degree of irritation is produced, and it is suddenly evacuated, or lastly from the absorption of the more liquid parts of the bile, the remainder becomes inspissated, and chrystallizes into masses too large to pass, and forms another kind of jaundice, where the bile-duct is not quite paralytic, or has regained its irritability. This disease is attended with much pain, which at first is felt at the pit of the stomach, exactly in the centre of the body, where the bile-duct enters the duodenum; afterwards, when the size of the bile-stones increase, it is also felt on the right side, where the gall-bladder is situated. The former pain at the pit of the stomach recurs by intervals, as the bile-stone is pushed against the neck of the duct; like the paroxysms of the stone in the urinary bladder, the other is a more dull and constant pain. Where these bile-stones are too large to pass, and the bile-ducts possess their sensibility, this becomes a very painful and hopeless disease. I made the following experiments with a view to their chemical solution. Some fragments of the same bile-stone were put into the weak spirit of marine salt, which is sold in the shops, and into solution of mild alcali; and into a solution of caustic alcali; and into oil of turpentine; without their being dissolved. All these mixtures were after some time put into a heat of boiling water, and then the oil of turpentine dissolved its fragments of bile-stone, but no alteration was produced upon those in the other liquids except some change of their colour. Some fragments of the same bile-stone were put into vitriolic æther, and were quickly dissolved without additional heat. Might not æther mixed with yolk of egg or with honey be given advantageously in bilious concretions? I have in two instances seen from 30 to 50 bile-stones come away by stool, about the size of large peas, after having given six grains of calomel in the evening, and four ounces of oil of almonds or olives on the succeeding morning. I have also given half a pint of good olive or almond oil as an emetic during the painful fit, and repeated it in half an hour, if the first did not operate, with frequent good effect. 4. Another disease of the liver, which I have several times observed, consists in the inability or paralysis of the secretory vessels. This disease has generally the same cause as the preceding one, the too frequent potation of spirituous liquors, or the too sudden omission of them, after the habit is confined; and is greater or less in proportion, as the whole or a part of the liver is affected, and as the inability or paralysis is more or less complete. This palsy of the liver is known from these symptoms, the patients have generally passed the meridian of life, have drank fermented liquors daily, but perhaps not been opprobrious drunkards; they lose their appetite, then their flesh and strength diminish in consequence, there appears no bile in their stools, nor in their urine, nor is any hardness or swelling perceptible on the region of the liver. But what is peculiar to this disease, and distinguishes it from all others at the first glance of the eye, is the bombycinous colour of the skin, which, like that of full-grown silkworms, has a degree of transparency with a yellow tint not greater than is natural to the serum of the blood. Mr. C. and Mr. B. both very strong men, between 50 and 60 years of age, who had drank ale at their meals instead of small beer, but were not reputed hard-drinkers, suddenly became weak, lost their appetite, flesh, and strength, with all the symptoms above enumerated, and died in about two months from the beginning of their malady. Mr. C. became anasarcous a few days before his death, and Mr. B. had frequent and great hæmorrhages from an issue, and some parts of his mouth, a few days before his death. In both these cases calomel, bitters and chalybeates were repeatedly used without effect. One of the patients described above, Mr. C, was by trade a plumber; both of them could digest no food, and died apparently for want of blood. Might not the transfusion of blood be used in these cases with advantage? 5. When the paralysis of the hepatic glands is less complete, or less universal, a schirrosity of some part of the liver is induced; for the secretory vessels retaining some of their living power take up a fluid from the circulation, without being sufficiently irritable to carry it forwards to their excretory ducts; hence the body, or receptacle of each gland, becomes inflated, and this distension increases, till by its very great stimulus inflammation is produced, or till those parts of the viscus become totally paralytic. This disease is distinguishable from the foregoing by the palpable hardness or largeness of the liver; and as the hepatic glands are not totally paralytic, or the whole liver not affected, some bile continues to be made. The inflammations of this viscus, consequent to the schirrosity of it, belong to the diseases of the sensitive motions, and will be treated of hereafter. 6. The ancients are said to have possessed an art of increasing the livers of geese to a size greater than the remainder of the goose. Martial. l. 13. epig. 58.--This is said to have been done by fat and figs. Horace, l. 2. sat. 8.--Juvenal sets these large livers before an epicure as a great rarity. Sat. 5. l. 114; and Persius, sat. 6. l. 71. Pliny says these large goose-livers were soaked in mulled milk, that is, I suppose, milk mixed with honey and wine; and adds, "that it is uncertain whether Scipio Metellus, of consular dignity, or M. Sestius, a Roman knight, was the great discoverer of this excellent dish." A modern traveller, I believe Mr. Brydone, asserts that the art of enlarging the livers of geese still exists in Sicily; and it is to be lamented that he did not import it into his native country, as some method of affecting the human liver might perhaps have been collected from it; besides the honour he might have acquired in improving our giblet pies. Our wiser caupones, I am told, know how to fatten their fowls, as well as their geese, for the London markets, by mixing gin instead of figs and fat with their food; by which they are said to become sleepy, and to fatten apace, and probably acquire enlarged livers; as the swine are asserted to do, which are fed on the sediments of barrels in the distilleries; and which so frequently obtains in those, who ingurgitate much ale, or wine, or drams. II. The irritative diseases of the kidneys, pancreas, spleen, and other glands, are analogous to those of the liver above described, differing only in the consequences attending their inability to action. For instance, when the secretory vessels of the kidneys become disobedient to the stimulus of the passing current of blood, no urine is separated or produced by them; their excretory mouths become filled with concreted mucus, or calculus matter, and in eight or ten days stupor and death supervenes in consequence of the retention of the feculent part of the blood. This disease in a slighter degree, or when only a part of the kidney is affected, is succeeded by partial inflammation of the kidney in consequence of previous torpor. In that case greater actions of the secretory vessels occur, and the nucleus of gravel is formed by the inflamed mucous membranes of the tubuli uriniferi, as farther explained in its place. This torpor, or paralysis of the secretory vessels of the kidneys, like that of the liver, owes its origin to their being previously habituated to too great stimulus; which in this country is generally owing to the alcohol contained in ale or wine; and hence must be registered amongst the diseases owing to inebriety; though it may be caused by whatever occasionally inflames the kidney; as too violent riding on horseback, or the cold from a damp bed, or by sleeping on the cold ground; or perhaps by drinking in general too little aqueous fluids. III. I shall conclude this section on the diseases of the liver induced by spirituous liquors, with the well known story of Prometheus, which seems indeed to have been invented by physicians in those ancient times, when all things were clothed in hieroglyphic, or in fable. Prometheus was painted as stealing fire from heaven, which might well represent the inflammable spirit produced by fermentation; which may be said to animate or enliven the man of clay: whence the conquests of Bacchus, as well as the temporary mirth and noise of his devotees. But the after punishment of those, who steal this accursed fire, is a vulture gnawing the liver; and well allegorises the poor inebriate lingering for years under painful hepatic diseases. When the expediency of laying a further tax on the distillation of spirituous liquors from grain was canvassed before the House of Commons some years ago, it was said of the distillers, with great truth, "_They take the bread from the people, and convert it into poison!_" Yet is this manufactory of disease permitted to continue, as appears by its paying into the treasury above 900,000l. near a million of money annually. And thus, under the names of rum, brandy, gin, whisky, usquebaugh, wine, cyder, beer, and porter, alcohol is become the bane of the Christian world, as opium of the Mahometan. Evoe! parce, liber? Parce, gravi metuende thirso!--Hor. * * * * * SECT. XXXI. OF TEMPERAMENTS. I. _The temperament of decreased irritability known by weak pulse, large pupils of the eyes, cold extremities. Are generally supposed to be too irritable. Bear pain better than labour. Natives of North-America contrasted with those upon the coast of Africa. Narrow and broad shouldered people. Irritable constitutions bear labour better than pain._ II. _Temperament of increased sensibility. Liable to intoxication, to inflammation, hæmoptoe, gutta serena, enthusiasm, delirium, reverie. These constitutions are indolent to voluntary exertions, and dull to irritations. The natives of South-America, and brute animals of this temperament._ III. _Of increased voluntarity; these are subject to locked jaw, convulsions, epilepsy, mania. Are very active, bear cold, hunger, fatigue. Are suited to great exertions. This temperament distinguishes mankind from other animals._ IV. _Of increased association. These have great memories, are liable to quartan agues, and stronger sympathies of parts with each other._ V. _Change of temperaments into one another._ Antient writers have spoken much of temperaments, but without sufficient precision. By temperament of the system should be meant a permanent predisposition to certain classes of diseases: without this definition a temporary predisposition to every distinct malady might be termed a temperament. There are four kinds of constitution, which permanently deviate from good health, and are perhaps sufficiently marked to be distinguished from each other, and constitute the temperaments or predispositions to the irritative, sensitive, voluntary, and associate classes of diseases. I. _The Temperament of decreased Irritability._ The diseases, which are caused by irritation, most frequently originate from the defect of it; for those, which are immediately owing to the excess of it, as the hot fits of fever, are generally occasioned by an accumulation of sensorial power in consequence of a previous defect of irritation, as in the preceding cold fits of fever. Whereas the diseases, which are caused by sensation and volition, most frequently originate from the excess of those sensorial powers, as will be explained below. The temperament of decreased irritability appears from the following circumstances, which shew that the muscular fibres or organs of sense are liable to become torpid or quiescent from less defect of stimulation than is productive of torpor or quiescence in other constitutions. 1. The first is the weak pulse, which in some constitutions is at the same time quick. 2. The next most marked criterion of this temperament is the largeness of the aperture of the iris, or pupil of the eye, which has been reckoned by some a beautiful feature in the female countenance, as an indication of delicacy, but to an experienced observer it is an indication of debility, and is therefore a defect, not an excellence. The third most marked circumstance in this constitution is, that the extremities, as the hands and feet, or nose and ears, are liable to become cold and pale in situations in respect to warmth, where those of greater strength are not affected. Those of this temperament are subject to hysteric affections, nervous fevers, hydrocephalus, scrophula, and consumption, and to all other diseases of debility. Those, who possess this kind of constitution, are popularly supposed to be more irritable than is natural, but are in reality less so. This mistake has arisen from their generally having a greater quickness of pulse, as explained in Sect. XII. 1. 4. XII. 3. 3.; but this frequency of pulse is not necessary to the temperament, like the debility of it. Persons of this temperament are frequently found amongst the softer sex, and amongst narrow-shouldered men; who are said to bear labour worse, and pain better than others. This last circumstance is supposed to have prevented the natives of North America from having been made slaves by the Europeans. They are a narrow-shouldered race of people, and will rather expire under the lash, than be made to labour. Some nations of Asia have small hands, as may be seen by the handles of their scymetars; which with their narrow shoulders shew, that they have not been accustomed to so great labour with their hands and arms, as the European nations in agriculture, and those on the coasts of Africa in swimming and rowing. Dr. Maningham, a popular accoucheur in the beginning of this century, observes in his aphorisms, that broad-shouldered men procreate broad-shouldered children. Now as labour strengthens the muscles employed, and increases their bulk, it would seem that a few generations of labour or of indolence may in this respect change the form and temperament of the body. On the contrary, those who are happily possessed of a great degree of irritability, bear labour better than pain; and are strong, active, and ingenious. But there is not properly a temperament of increased irritability tending to disease, because an increased quantity of irritative motions generally induces an increase of pleasure or pain, as in intoxication, or inflammation; and then the new motions are the immediate consequences of increased sensation, not of increased irritation; which have hence been so perpetually confounded with each other. II. _Temperament of Sensibility._ There is not properly a temperament, or predisposition to disease, from decreased sensibility, since irritability and not sensibility is immediately necessary to bodily health. Hence it is the excess of sensation alone, as it is the defect of irritation, that most frequently produces disease. This temperament of increased sensibility is known from the increased activity of all those motions of the organs of sense and muscles, which are exerted in consequence of pleasure or pain, as in the beginning of drunkenness, and in inflammatory fever. Hence those of this constitution are liable to inflammatory diseases, as hepatitis; and to that kind of consumption which is hereditary, and commences with slight repeated hæmoptoe. They have high-coloured lips, frequently dark hair and dark eyes with large pupils, and are in that case subject to gutta serena. They are liable to enthusiasm, delirium, and reverie. In this last circumstance they are liable to start at the clapping of a door; because the more intent any one is on the passing current of his ideas, the greater surprise he experiences on their being dissevered by some external violence, as explained in Sect. XIX. on reverie. As in these constitutions more than the natural quantities of sensitive motions are produced by the increased quantity of sensation existing in the habit, it follows, that the irritative motions will be performed in some degree with less energy, owing to the great expenditure of sensorial power on the sensitive ones. Hence those of this temperament do not attend to slight stimulations, as explained in Sect. XIX. But when a stimulus is so great as to excite sensation, it produces greater sensitive actions of the system than in others; such as delirium or inflammation. Hence they are liable to be absent in company; sit or lie long in one posture; and in winter have the skin of their legs burnt into various colours by the fire. Hence also they are fearful of pain; covet music and sleep; and delight in poetry and romance. As the motions in consequence of sensation are more than natural, it also happens from the greater expenditure of sensorial power on them, that the voluntary motions are less easily exerted. Hence the subjects of this temperament are indolent in respect to all voluntary exertions, whether of mind or body. A race of people of this description seems to have been found by the Spaniards in the islands of America, where they first landed, ten of whom are said not to have consumed more food than one Spaniard, nor to have been capable of more than one tenth of the exertion of a Spaniard. Robertson's History.--In a state similar to this the greatest part of the animal world pass their lives, between sleep or inactive reverie, except when they are excited by the call of hunger. III. _The Temperament of increased Voluntarity._ Those of this constitution differ from both the last mentioned in this, that the pain, which gradually subsides in the first, and is productive of inflammation or delirium in the second, is in this succeeded by the exertion of the muscles or ideas, which are most frequently connected with volition; and they are thence subject to locked jaw, convulsions, epilepsy, and mania, as explained in Sect. XXXIV. Those of this temperament attend to the slightest irritations or sensations, and immediately exert themselves to obtain or avoid the objects of them; they can at the same time bear cold and hunger better than others, of which Charles the Twelfth of Sweden was an instance. They are suited and generally prompted to all great exertions of genius or labour, as their desires are more extensive and more vehement, and their powers of attention and of labour greater. It is this facility of voluntary exertion, which distinguishes men from brutes, and which has made them lords of the creation. IV. _The Temperament of increased Association._ This constitution consists in the too great facility, with which the fibrous motions acquire habits of association, and by which these associations become proportionably stronger than in those of the other temperaments. Those of this temperament are slow in voluntary exertions, or in those dependent on sensation, or on irritation. Hence great memories have been said to be attended with less sense and less imagination from Aristotle down to the present time; for by the word memory these writers only understood the unmeaning repetition of words or numbers in the order they were received, without any voluntary efforts of the mind. In this temperament those associations of motions, which are commonly termed sympathies, act with greater certainty and energy, as those between disturbed vision and the inversion of the motion of the stomach, as in sea-sickness; and the pains in the shoulder from hepatic inflammation. Add to this, that the catenated circles of actions are of greater extent than in the other constitutions. Thus if a strong vomit or cathartic be exhibited in this temperament, a smaller quantity will produce as great an effect, if it be given some weeks afterwards; whereas in other temperaments this is only to be expected, if it be exhibited in a few days after the first dose. Hence quartan agues are formed in those of this temperament, as explained in Section XXXII. on diseases from irritation, and other intermittents are liable to recur from slight causes many weeks after they have been cured by the bark. V. The first of these temperaments differs from the standard of health from defect, and the others from excess of sensorial power; but it sometimes happens that the same individual, from the changes introduced into his habit by the different seasons of the year, modes or periods of life, or by accidental diseases, passes from one of these temperaments to another. Thus a long use of too much fermented liquor produces the temperament of increased sensibility; great indolence and solitude that of decreased irritability; and want of the necessaries of life that of increased voluntarity. * * * * * SECT. XXXII. DISEASES OF IRRITATION. I. _Irritative fevers with strong pulse. With weak pulse. Symptoms of fever, Their source._ II. 1. _Quick pulse is owing to decreased irritability_. 2. _Not in sleep or in apoplexy._ 3. _From inanition. Owing to deficiency of sensorial power._ III. 1. _Causes of fever. From defect of heat. Heat from secretions. Pain of cold in the loins and forehead._ 2. _Great expense of sensorial power in the vital motions. Immersion in cold water. Succeeding glow of heat. Difficult respiration in cold bathing explained. Why the cold bath invigorates. Bracing and relaxation are mechanical terms._ 3. _Uses of cold bathing. Uses of cold air in fevers._ 4. _Ague fits from cold air. Whence their periodical returns._ IV. _Defect of distention a cause of fever. Deficiency of blood. Transfusion of blood._ V. 1. _Defect of momentum of the blood from mechanic stimuli. 2. Air injected into the blood-vessels._ 3. _Exercise increases the momentum of the blood._ 4. _Sometimes bleeding increases the momentum of it._ VI. _Influence of the sun and moon on diseases. The chemical stimulus of the blood. Menstruation obeys the lunations. Queries._ VII. _Quiesence of large glands a cause of fever. Swelling of the præcordia._ VIII. _Other causes of quiescence, as hunger, bad air, fear, anxiety._ IX. 1. _Symptoms of the cold fit._ 2. _Of the hot fit._ 3. _Second cold fit why._ 4. _Inflammation introduced, or delirium, or stupor._ X. _Recapitulation. Fever not an effort of nature to relieve herself. Doctrine of spasm._ I. When the contractile sides of the heart and arteries perform a greater number of pulsations in a given time, and move through a greater area at each pulsation, whether these motions are occasioned by the stimulus of the acrimony or quantity of the blood, or by their association with other irritative motions, or by the increased irritability of the arterial system, that is, by an increased quantity of sensorial power, one kind of fever is produced; which may be called Synocha irritativa, or Febris irritativa pulsu forti, or irritative fever with strong pulse. When the contractile sides of the heart and arteries perform a greater number of pulsations in a given time, but move through a much less area at each pulsation, whether these motions are occasioned by defect of their natural stimuli, or by the defect of other irritative motions with which they are associated, or from the inirritability of the arterial system, that is, from a decreased quantity of sensorial power, another kind of fever arises; which may be termed, Typhus irritativus, or Febris irritativa pulsu debili, or irritative fever with weak pulse. The former of these fevers is the synocha of nosologists, and the latter the typhus mitior, or nervous fever. In the former there appears to be an increase of sensorial power, in the latter a deficiency of it; which is shewn to be the immediate cause of strength and weakness, as defined in Sect. XII. 1. 3. It should be added, that a temporary quantity of strength or debility may be induced by the defect or excess of stimulus above what is natural; and that in the same fever _debility always exists during the cold fit, though strength does not always exist during the hot fit._ These fevers are always connected with, and generally induced by, the disordered irritative motions of the organs of sense, or of the intestinal canal, or of the glandular system, or of the absorbent system; and hence are always complicated with some or many of these disordered motions, which are termed the symptoms of the fever, and which compose the great variety in these diseases. The irritative fevers both with strong and with weak pulse, as well as the sensitive fevers with strong and with weak pulse, which are to be described in the next section, are liable to periodical remissions, and then they take the name of intermittent fevers, and are distinguished by the periodical times of their access. II. For the better illustration of the phenomena of irritative fevers we must refer the reader to the circumstances of irritation explained in Sect. XII. and shall commence this intricate subject by speaking of the quick pulse, and proceed by considering many of the causes, which either separately or in combination most frequently produce the cold fits of fevers. 1. If the arteries are dilated but to half their usual diameters, though they contract twice as frequently in a given time, they will circulate only half their usual quantity of blood: for as they are cylinders, the blood which they contain must be as the squares of their diameters. Hence when the pulse becomes quicker and smaller in the same proportion, the heart and arteries act with less energy than in their natural state. See Sect. XII. 1. 4. That this quick small pulse is owing to want of irritability, appears, first, because it attends other symptoms of want of irritability; and, secondly, because on the application of a stimulus greater than usual, it becomes slower and larger. Thus in cold fits of agues, in hysteric palpitations of the heart, and when the body is much exhausted by hæmorrhages, or by fatigue, as well as in nervous fevers, the pulse becomes quick and small; and secondly, in all those cases if an increase of stimulus be added, by giving a little wine or opium; the quick small pulse becomes slower and larger, as any one may easily experience on himself, by counting his pulse after drinking one or two glasses of wine, when he is faint from hunger or fatigue. Now nothing can so strongly evince that this quick small pulse is owing to defect of irritability, than that an additional stimulus, above what is natural, makes it become slower and larger immediately: for what is meant by a defect of irritability, but that the arteries and heart are not excited into their usual exertions by their usual quantity of stimulus? but if you increase the quantity of stimulus, and they immediately act with their usual energy, this proves their previous want of their natural degree of irritability. Thus the trembling hands of drunkards in a morning become steady, and acquire strength to perform their usual offices, by the accustomed stimulus of a glass or two of brandy. 2. In sleep and in apoplexy the pulse becomes slower, which is not owing to defect of irritability, for it is at the same time larger; and thence the quantity of the circulation is rather increased than diminished. In these cases the organs of sense are closed, and the voluntary power is suspended, while the motions dependent on internal irritations, as those of digestion and secretion, are carried on with more than their usual vigour; which has led superficial observers to confound these cases with those arising from want of irritability. Thus if you lift up the eyelid of an apoplectic patient, who is not actually dying, the iris will, as usual, contract itself, as this motion is associated with the stimulus of light; but it is not so in the last stages of nervous fevers, where the pupil of the eye continues expanded in the broad day-light: in the former case there is a want of voluntary power, in the latter a want of irritability. Hence also those constitutions which are deficient in quantity of irritability, and which possess too great sensibility, as during the pain of hunger, of hysteric spasms, or nervous headachs, are generally supposed to have too much irritability; and opium, which in its due dose is a most powerful stimulant, is erroneously called a sedative; because by increasing the irritative motions it decreases the pains arising from defect of them. Why the pulse should become quicker both from an increase of irritation, as in the synocha irritativa, or irritative fever with strong pulse; and from the decrease of it, as in the typhus irritativus, or irritative fever with weak pulse; seems paradoxical. The former circumstance needs no illustration; since if the stimulus of the blood, or the irritability of the sanguiferous system be increased, and the strength of the patient not diminished, it is plain that the motions must be performed quicker and stronger. In the latter circumstance the weakness of the muscular power of the heart is soon over-balanced by the elasticity of the coats of the arteries, which they possess besides a muscular power of contraction; and hence the arteries are distended to less than their usual diameters. The heart being thus stopped, when it is but half emptied, begins sooner to dilate again; and the arteries being dilated to less than their usual diameters, begin so much sooner to contract themselves; insomuch, that in the last stages of fevers with weakness the frequency of pulsation of the heart and arteries becomes doubled; which, however, is never the case in fevers with strength, in which they seldom exceed 118 or 120 pulsations in a minute. It must be added, that in these cases, while the pulse is very small and very quick, the heart often feels large, and labouring to one's hand; which coincides with the above explanation, shewing that it does not completely empty itself. 3. In cases however of debility from paucity of blood, as in animals which are bleeding to death in the slaughter-house, the quick pulsations of the heart and arteries may be owing to their not being distended to more than half their usual diastole; and in consequence they must contract sooner, or more frequently, in a given time. As weak people are liable to a deficient quantity of blood, this cause may occasionally contribute to quicken the pulse in fevers with debility, which may be known by applying one's hand upon the heart as above; but the principal cause I suppose to consist in the diminution of sensorial power. When a muscle contains, or is supplied with but little sensorial power, its contraction soon ceases, and in consequence may soon recur, as is seen in the trembling hands of people weakened by age or by drunkenness. See Sect. XII. 1. 4. XII. 3. 4. It may nevertheless frequently happen, that both the deficiency of stimulus, as where the quantity of blood is lessened (as described in No. 4. of this section), and the deficiency of sensorial power, as in those of the temperament of irritability, described in Sect. XXXI. occur at the same time; which will thus add to the quickness of the pulse and to the danger of the disease. III. 1. A certain degree of heat is necessary to muscular motion, and is, in consequence, essential to life. This is observed in those animals and insects which pass the cold season in a torpid state, and which revive on being warmed by the fire. This necessary stimulus of heat has two sources; one from the fluid atmosphere of heat, in which all things are immersed, and the other from the internal combinations of the particles, which form the various fluids, which are produced in the extensive systems of the glands. When either the external heat, which surrounds us, or the internal production of it, becomes lessened to a certain degree, the pain of cold is perceived. This pain of cold is experienced most sensibly by our teeth, when ice is held in the mouth; or by our whole system after having been previously accustomed to much warmth. It is probable, that this pain does not arise from the mechanical or chemical effects of a deficiency of heat; but that, like the organs of sense by which we perceive hunger and thirst, this sense of heat suffers pain, when the stimulus of its object is wanting to excite the irritative motions of the organ; that is, when the sensorial power becomes too much accumulated in the quiescent fibres. See Sect. XII. 5. 3. For as the peristaltic motions of the stomach are lessened, when the pain of hunger is great, so the action of the cutaneous capillaries are lessened during the pain of cold; as appears by the paleness of the skin, as explained in Sect. XIV. 6. on the production of ideas. The pain in the small of the back and forehead in the cold fits of the ague, in nervous hemicrania, and in hysteric paroxysms, when all the irritative motions are much impaired, seems to arise from this cause; the vessels of these membranes or muscles become torpid by their irritative associations with other parts of the body, and thence produce less of their accustomed secretions, and in consequence less heat is evolved, and they experience the pain of cold; which coldness may often be felt by the hand applied upon the affected part. 2. The importance of a greater or less deduction of heat from the system will be more easy to comprehend, if we first consider the great expense of sensorial power used in carrying on the vital motions; that is, which circulates, absorbs, secretes, aerates, and elaborates the whole mass of fluids with unceasing assiduity. The sensorial power, or spirit of animation, used in giving perpetual and strong motion to the heart, which overcomes the elasticity and vis inertiæ of the whole arterial system; next the expense of sensorial power in moving with great force and velocity the innumerable trunks and ramifications of the arterial system; the expense of sensorial power in circulating the whole mass of blood through the long and intricate intortions of the very fine vessels, which compose the glands and capillaries; then the expense of sensorial power in the exertions of the absorbent extremities of all the lacteals, and of all the lymphatics, which open their mouths on the external surface of the skin, and on the internal surfaces of every cell or interstice of the body; then the expense of sensorial power in the venous absorption, by which the blood is received from the capillary vessels, or glands, where the arterial power ceases, and is drank up, and returned to the heart; next the expense of sensorial power used by the muscles of respiration in their office of perpetually expanding the bronchia, or air-vessels, of the lungs; and lastly in the unceasing peristaltic motions of the stomach and whole system of intestines, and in all the secretions of bile, gastric juice, mucus, perspirable matter, and the various excretions from the system. If we consider the ceaseless expense of sensorial power thus perpetually employed, it will appear to be much greater in a day than all the voluntary exertions of our muscles and organs of sense consume in a week; and all this without any sensible fatigue! Now, if but a part of these vital motions are impeded, or totally stopped for but a short time, we gain an idea, that there must be a great accumulation of sensorial power; as its production in these organs, which are subject to perpetual activity, is continued during their quiescence, and is in consequence accumulated. While, on the contrary, where those vital organs act too forcibly by increase of stimulus without a proportionally-increased production of sensorial power in the brain, it is evident, that a great deficiency of action, that is torpor, must soon follow, as in fevers; whereas the locomotive muscles, which act only by intervals, are neither liable to so great accumulation of sensorial power during their times of inactivity, nor to so great an exhaustion of it during their times of action. Thus, on going into a very cold bath, suppose at 33 degrees of heat on Fahrenheit's scale, the action of the subcutaneous capillaries, or glands, and of the mouths of the cutaneous absorbents is diminished, or ceases for a time. Hence less or no blood passes these capillaries, and paleness succeeds. But soon after emerging from the bath, a more florid colour and a greater degree of heat is generated on the skin than was possessed before immersion; for the capillary glands, after this quiescent state, occasioned by the want of stimulus, become more irritable than usual to their natural stimuli, owing to the accumulation of sensorial power, and hence a greater quantity of blood is transmitted through them, and a greater secretion of perspirable matter; and, in consequence, a greater degree of heat succeeds. During the continuance in cold water the breath is cold, and the act of respiration quick and laborious; which have generally been ascribed to the obstruction of the circulating fluid by a spasm of the cutaneous vessels, and by a consequent accumulation of blood in the lungs, occasioned by the pressure as well as by the coldness of the water. This is not a satisfactory account of this curious phænomenon, since at this time the whole circulation is less, as appears from the smallness of the pulse and coldness of the breath; which shew that less blood passes through the lungs in a given time; the same laborious breathing immediately occurs when the paleness of the skin is produced by fear, where no external cold or pressure are applied. The minute vessels of the bronchia, through which the blood passes from the arterial to the venal system, and which correspond with the cutaneous capillaries, have frequently been exposed to cold air, and become quiescent along with those of the skin; and hence their motions are so associated together, that when one is affected either with quiescence or exertion, the other sympathizes with it, according to the laws of irritative association. See Sect. XXVII. 1. on hæmorrhages. Besides the quiescence of the minute vessels of the lungs, there are many other systems of vessels which become torpid from their irritative associations with those of the skin, as the absorbents of the bladder and intestines; whence an evacuation of pale urine occurs, when the naked skin is exposed only to the coldness of the atmosphere; and sprinkling the naked body with cold water is known to remove even pertinacious constipation of the bowels. From the quiescence of such extensive systems of vessels as the glands and capillaries of the skin, and the minute vessels of the lungs, with their various absorbent series of vessels, a great accumulation of sensorial powers is occasioned; part of which is again expended in the increased exertion of all these vessels, with an universal glow of heat in consequence of this exertion, and the remainder of it adds vigour to both the vital and voluntary exertions of the whole day. If the activity of the subcutaneous vessels, and of those with which their actions are associated, was too great before cold immersion, as in the hot days of summer, and by that means the sensorial power was previously diminished, we see the cause why the cold bath gives such present strength; namely, by stopping the unnecessary activity of the subcutaneous vessels, and thus preventing the too great exhaustion of sensorial power; which, in metaphorical language, has been called _bracing_ the system: which is, however, a mechanical term, only applicable to drums, or musical strings: as on the contrary the word _relaxation_, when applied to living animal bodies, can only mean too small a quantity of stimulus, or too small a quantity of sensorial power; as explained in Sect. XII. 1. 3. This experiment of cold bathing presents us with a simple fever-fit; for the pulse is weak, small, and quick during the cold immersion; and becomes strong, full, and quick during the subsequent glow of heat; till in a few minutes these symptoms subside, and the temporary fever ceases. In those constitutions where the degree of inirritability, or of debility, is greater than natural, the coldness and paleness of the skin with the quick and weak pulse continue a long time after the patient leaves the bath; and the subsequent heat approaches by unequal flushings, and he feels himself disordered for many hours. Hence the bathing in a cold spring of water, where the heat is but forty-eight degrees on Fahrenheit's thermometer, much disagrees with those of weak or inirritable habits of body; who possess so little sensorial power, that they cannot without injury bear to have it diminished even for a short time; but who can nevertheless bear the more temperate coldness of Buxton bath, which is about eighty degrees of heat, and which strengthens them, and makes them by habit less liable to great quiescence from small variations of cold, and thence less liable to be disordered by the unavoidable accidents of life. Hence it appears, why people of these inirritable constitutions, which is another expression for sensorial deficiency, are often much injured by bathing in a cold spring of water; and why they should continue but a very short time in baths, which are colder than their bodies; and should gradually increase both the degree of coldness of the water, and the time of their continuance in it, if they would obtain salutary effects from cold immersions. See Sect. XII. 2. 1. On the other hand, in all cases where the heat of the external surface of the body, or of the internal surface of the lungs, is greater than natural, the use of exposure to cool air may be deduced. In fever-fits attended with strength, that is with great quantity of sensorial power, it removes the additional stimulus of heat from the surfaces above mentioned, and thus prevents their excess of useless motion; and in fever-fits attended with debility, that is with a deficiency of the quantity of sensorial power, it prevents the great and dangerous waste of sensorial power expended in the unnecessary increase of the actions of the glands and capillaries of the skin and lungs. 4. In the same manner, when any one is long exposed to very cold air, a quiescence is produced of the cutaneous and pulmonary capillaries and absorbents, owing to the deficiency of their usual stimulus of heat; and this quiescence of so great a quantity of vessels affects, by irritative association, the whole absorbent and glandular system, which becomes in a greater or less degree quiescent, and a cold fit of fever is produced. If the deficiency of the stimulus of heat is very great, the quiescence becomes so general as to extinguish life, as in those who are frozen to death. If the deficiency of heat be in less degree, but yet so great as in some measure to disorder the system, and should occur the succeeding day, it will induce a greater degree of quiescence than before, from its acting in concurrence with the period of the diurnal circle of actions, explained in Sect. XXXVI. Hence from a small beginning a greater and greater degree of quiescence may be induced, till a complete fever-fit is formed; and which will continue to recur at the periods by which it was produced. See Sect. XVII. 3. 6. If the degree of quiescence occasioned by defect of the stimulus of heat be very great, it will recur a second time by a slighter cause, than that which first induced it. If the cause, which induces the second fit of quiescence, recurs the succeeding day, the quotidian fever is produced; if not till the alternate day, the tertian fever; and if not till after seventy-two hours from the first fit of quiescence, the quartan fever is formed. This last kind of fever recurs less frequently than the other, as it is a disease only of those of the temperament of associability, as mentioned in Sect. XXXI.; for in other constitutions the capability of forming a habit ceases, before the new cause of quiescence is again applied, if that does not occur sooner than in seventy-two hours. And hence those fevers, whose cause is from cold air of the night or morning, are more liable to observe the solar day in their periods; while those from other causes frequently observe the lunar day in their periods, their paroxysms returning near an hour later every day, as explained in Sect. XXXVI. IV. Another frequent cause of the cold fits of fever is the defect of the stimulus of distention. The whole arterial system would appear, by the experiments of Haller, to be irritable by no other stimulus, and the motions of the heart and alimentary canal are certainly in some measure dependant on the same cause. See Sect. XIV. 7. Hence there can be no wonder, that the diminution of distention should frequently induce the quiescence, which constitutes the beginning of fever-fits. Monsieur Leiutaud has judiciously mentioned the deficiency of the quantity of blood amongst the causes of diseases, which he says is frequently evident in dissections: fevers are hence brought on by great hæmorrhages, diarrhoeas, or other evacuations; or from the continued use of diet, which contains but little nourishment; or from the exhaustion occasioned by violent fatigue, or by those chronic diseases in which the digestion is much impaired; as where the stomach has been long affected with the gout or schirrus; or in the paralysis of the liver, as described in Sect. XXX. Hence a paroxysm of gout is liable to recur on bleeding or purging; as the torpor of some viscus, which precedes the inflammation of the foot, is thus induced by the want of the stimulus of distention. And hence the extremities of the body, as the nose and fingers, are more liable to become cold, when we have long abstained from food; and hence the pulse is increased both in strength and velocity above the natural standard after a full meal by the stimulus of distention. However, this stimulus of distention, like the stimulus of heat above described, though it contributes much to the due action not only of the heart, arteries, and alimentary canal, but seems necessary to the proper secretion of all the various glands; yet perhaps it is not the sole cause of any of these numerous motions: for as the lacteals, cutaneous absorbents, and the various glands appear to be stimulated into action by the peculiar pungency of the fluids they absorb, so in the intestinal canal the pungency of the digesting aliment, or the acrimony of the fæces, seem to contribute, as well as their bulk, to promote the peristaltic motions; and in the arterial system, the momentum of the particles of the circulating blood, and their acrimony, stimulate the arteries, as well as the distention occasioned by it. Where the pulse is small this defect of distention is present, and contributes much to produce the febris irritativa pulsu debili, or irritative fever with weak pulse, called by modern writers nervous fever, as a predisponent cause. See Sect. XII. 1. 4. Might not the transfusion of blood, suppose of four ounces daily from a strong man, or other healthful animal, as a sheep or an ass, be used in the early state of nervous or putrid fevers with great prospect of success? V. 1. The defect of the momentum of the particles of the circulating blood is another cause of the quiescence, with which the cold fits of fever commence. This stimulus of the momentum of the progressive particles of the blood does not act over the whole body like those of heat and distention above described, but is confined to the arterial system; and differs from the stimulus of the distention of the blood, as much as the vibration of the air does from the currents of it. Thus are the different organs of our bodies stimulated by four different mechanic properties of the external world: the sense of touch by the pressure of solid bodies so as to distinguish their figure; the muscular system by the distention, which they occasion; the internal surface of the arteries, by the momentum of their moving particles; and the auditory nerves, by the vibration of them: and these four mechanic properties are as different from each other as the various chemical ones, which are adapted to the numerous glands, and to the other organs of sense. 2. The momentum of the progressive particles of blood is compounded of their velocity and their quantity of matter: hence whatever circumstances diminish either of these without proportionally increasing the other, and without superadding either of the general stimuli of heat or distention, will tend to produce a quiescence of the arterial system, and from thence of all the other irritative motions, which are connected with it. Hence in all those constitutions or diseases where the blood contains a greater proportion of serum, which is the lightest part of its composition, the pulsations of the arteries are weaker, as in nervous fevers, chlorosis, and hysteric complaints; for in these cases the momentum of the progressive particles of blood is less: and hence, where the denser parts of its composition abound, as the red part of it, or the coagulable lymph, the arterial pulsations are stronger; as in those of robust health, and in inflammatory diseases. That this stimulus of the momentum of the particles of the circulating fluid is of the greatest consequence to the arterial action, appears from the experiment of injecting air into the blood vessels, which seems to destroy animal life from the want of this stimulus of momentum; for the distention of the arteries is not diminished by it, it possesses no corrosive acrimony, and is less liable to repass the valves than the blood itself; since air-valves in all machinery require much less accuracy of construction than those which are opposed to water. 3. One method of increasing the velocity of the blood, and in consequence the momentum of its particles, is by the exercise of the body, or by the friction of its surface: so, on the contrary, too great indolence contributes to decrease this stimulus of the momentum of the particles of the circulating blood, and thus tends to induce quiescence; as is seen in hysteric cases, and chlorosis, and the other diseases of sedentary people. 4. The velocity of the particles of the blood in certain circumstances is increased by venesection, which, by removing a part of it, diminishes the resistance to the motion of the other part, and hence the momentum of the particles of it is increased. This may be easily understood by considering it in the extreme, since, if the resistance was greatly increased, so as to overcome the propelling power, there could be no velocity, and in consequence no momentum at all. From this circumstance arises that curious phænomenon, the truth of which I have been more than once witness to, that venesection will often instantaneously relieve those nervous pains, which attend the cold periods of hysteric, asthmatic, or epileptic diseases; and that even where large doses of opium have been in vain exhibited. In these cases the pulse becomes stronger after the bleeding, and the extremities regain their natural warmth; and an opiate then given acts with much more certain effect. VI. There is another cause, which seems occasionally to induce quiescence into some part of our system, I mean the influence of the sun and moon; the attraction of these luminaries, by decreasing the gravity of the particles of the blood, cannot affect their momentum, as their vis inertiæ remains the same; but it may nevertheless produce some chemical change in them, because whatever affects the general attractions of the particles of matter may be supposed from analogy to affect their specific attractions or affinities: and thus the stimulus of the particles of blood may be diminished, though not their momentum. As the tides of the sea obey the southing and northing of the moon (allowing for the time necessary for their motion, and the obstructions of the shores), it is probable, that there are also atmospheric tides on both sides of the earth, which to the inhabitants of another planet might so deflect the light as to resemble the ring of Saturn. Now as these tides of water, or of air, are raised by the diminution of their gravity, it follows, that their pressure on the surface of the earth is no greater than the pressure of the other parts of the ocean, or of the atmosphere, where no such tides exist; and therefore that they cannot affect the mercury in the barometer. In the same manner, the gravity of all other terrestrial bodies is diminished at the times of the southing and northing of the moon, and that in a greater degree when this coincides with the southing and northing of the sun, and this in a still greater degree about the times of the equinoxes. This decrease of the gravity of all bodies during the time the moon passes our zenith or nadir might possibly be shewn by the slower vibrations of a pendulum, compared with a spring clock, or with astronomical observation. Since a pendulum of a certain length moves slower at the line than near the poles, because the gravity being diminished and the vis inertiæ continuing the same, the motive power is less, but the resistance to be overcome continues the same. The combined powers of the lunar and solar attraction is estimated by Sir Isaac Newton not to exceed one 7,868,850th part of the power of gravitation, which seems indeed but a small circumstance to produce any considerable effect on the weight of sublunary bodies, and yet this is sufficient to raise the tides at the equator above ten feet high; and if it be considered, what small impulses of other bodies produce their effects on the organs of sense adapted to the perception of them, as of vibration on the auditory nerves, we shall cease to to be surprised, that so minute a diminution in the gravity of the particles of blood should so far affect their chemical changes, or their stimulating quality, as, joined with other causes, sometimes to produce the beginnings of diseases. Add to this, that if the lunar influence produces a very small degree of quiescence at first, and if that recurs at certain periods even with less power to produce quiescence than at first, yet the quiescence will daily increase by the acquired habit acting at the same time, till at length so great a degree of quiescence is induced as to produce phrensy, canine madness, epilepsy, hysteric pains or cold fits of fever, instances of many of which are to be found in Dr. Mead's work on this subject. The solar influence also appears daily in several diseases; but as darkness, silence, sleep, and our periodical meals mark the parts of the solar circle of actions, it is sometimes dubious to which of these the periodical returns of these diseases are to be ascribed. As far as I have been able to observe, the periods of inflammatory diseases observe the solar day; as the gout and rheumatism have their greatest quiescence about noon and midnight, and their exacerbations some hours after; as they have more frequently their immediate cause from cold air, inanition, or fatigue, than from the effects of lunations: whilst the cold fits of hysteric patients, and those in nervous fevers, more frequently occur twice a day, later by near half an hour each time, according to the lunar day; whilst some fits of intermittents, which are undisturbed by medicines, return at regular solar periods, and others at lunar ones; which may, probably, be owing to the difference of the periods of those external circumstances of cold, inanition, or lunation, which immediately caused them. We must, however, observe, that the periods of quiescence and exacerbation in diseases do not always commence at the times of the syzygies or quadratures of the moon and sun, or at the times of their passing the zenith or nadir; but as it is probable, that the stimulus of the particles of the circumfluent blood is gradually diminished from the time of the quadratures to that of the syzygies, the quiescence may commence at any hour, when co-operating with other causes of quiescence, it becomes great enough to produce a disease: afterwards it will continue to recur at the same period of the lunar or solar influence; the same cause operating conjointly with the acquired habit, that is with the catenation of this new motion with the dissevered links of the lunar or solar circles of animal action. In this manner the periods of menstruation obey the lunar month with great exactness in healthy patients (and perhaps the venereal orgasm in brute animals does the same), yet these periods do not commence either at the syzygies or quadratures of the lunations, but at whatever time of the lunar periods they begin, they observe the same in their returns till some greater cause disturbs them. Hence, though the best way to calculate the time of the expected returns of the paroxysms of periodical diseases is to count the number of hours between the commencement of the two preceding fits, yet the following observations may be worth attending to, when we endeavour to prevent the returns of maniacal or epileptic diseases; whose periods (at the beginning of them especially) frequently observe the syzygies of the moon and sun, and particularly about the equinox. The greatest of the two tides happening in every revolution of the moon, is that when the moon approaches nearest to the zenith or nadir; for this reason, while the sun is in the northern signs, that is during the vernal and summer months, the greater of the two diurnal tides in our latitude is that, when the moon is above the horizon; and when the sun is in the southern signs, or during the autumnal and winter months, the greater tide is that, which arises when the moon is below the horizon: and as the sun approaches somewhat nearer the earth in winter than in summer, the greatest equinoctial tides are observed to be a little before the vernal equinox, and a little after the autumnal one. Do not the cold periods of lunar diseases commence a few hours before the southing of the moon during the vernal and summer months, and before the northing of the moon during the autumnal and winter months? Do not palsies and apoplexies, which occur about the equinoxes, happen a few days before the vernal equinoctial lunation, and after the autumnal one? Are not the periods of those diurnal diseases more obstinate, that commence many hours before the southing or northing of the moon, than of those which commence at those times? Are not those palsies and apoplexies more dangerous which commence many days before the syzygies of the moon, than those which happen at those times? See Sect. XXXVI. on the periods of diseases. VII. Another very frequent cause of the cold fit of fever is the quiescence of some of those large congeries of glands, which compose the liver, spleen, or pancreas; one or more of which are frequently so enlarged in the autumnal intermittents as to be perceptible to the touch externally, and are called by the vulgar ague-cakes. As these glands are stimulated into action by the specific pungency of the fluids, which they absorb, the general cause of their quiescence seems to be the too great insipidity of the fluids of the body, co-operating perhaps at the same time with other general causes of quiescence. Hence, in marshy countries at cold seasons, which have succeeded hot ones, and amongst those, who have lived on innutritious and unstimulating diet, these agues are most frequent. The enlargement of these quiescent viscera, and the swelling of the præcordia in many other fevers, is, most probably, owing to the same cause; which may consist in a general deficiency of the production of sensorial power, as well as in the diminished stimulation of the fluids; and when the quiescence of so great a number of glands, as constitute one of those large viscera, commences, all the other irritative motions are affected by their connection with it, and the cold fit of fever is produced. VIII. There are many other causes, which produce quiescence of some part of the animal system, as fatigue, hunger, thirst, bad diet, disappointed love, unwholesome air, exhaustion from evacuations, and many others; but the last cause, that we shall mention, as frequently productive of cold fits of fever, is fear or anxiety of mind. The pains, which we are first and most generally acquainted with, have been produced by defect of some stimulus; thus, soon after our nativity we become acquainted with the pain from the coldness of the air, from the want of respiration, and from the want of food. Now all these pains occasioned by defect of stimulus are attended with quiescence of the organ, and at the same time with a greater or less degree of quiescence of other parts of the system: thus, if we even endure the pain of hunger so as to miss one meal instead of our daily habit of repletion, not only the peristaltic motions of the stomach and bowels are diminished, but we are more liable to coldness of our extremities, as of our noses, and ears, and feet, than at other times. Now, as fear is originally excited by our having experienced pain, and is itself a painful affection, the same quiescence of other fibrous motions accompany it, as have been most frequently connected with this kind of pain, as explained in Sect. XVI. 8. 1. as the coldness and paleness of the skin, trembling, difficult respiration, indigestion, and other symptoms, which contribute to form the cold fit of fevers. Anxiety is fear continued through a longer time, and, by producing chronical torpor of the system, extinguishes life slowly, by what is commonly termed a broken heart. IX. 1. We now step forwards to consider the other symptoms in consequence of the quiescence which begins the fits of fever. If by any of the circumstances before described, or by two or more of them acting at the same time, a great degree of quiescence is induced on any considerable part of the circle of irritative motions, the whole class of them is more or less disturbed by their irritative associations. If this torpor be occasioned by a deficient supply of sensorial power, and happens to any of those parts of the system, which are accustomed to perpetual activity, as the vital motions, the torpor increases rapidly, because of the great expenditure of sensorial power by the incessant activity of those parts of the system, as shewn in No. 3. 2. of this Section. Hence a deficiency of all the secretions succeeds, and as animal heat is produced in proportion to the quantity of those secretions, the coldness of the skin is the first circumstance, which is attended to. Dr. Martin asserts, that some parts of his body were warmer than natural in the cold fit of fever; but it is certain, that those, which are uncovered, as the fingers, and nose, and ears, are much colder to the touch, and paler in appearance. It is possible, that his experiments were made at the beginning of the subsequent hot fits; which commence with partial distributions of heat, owing to some parts of the body regaining their natural irritability sooner than others. From the quiescence of the anastomosing capillaries a paleness of the skin succeeds, and a less secretion of the perspirable matter; from the quiescence of the pulmonary capillaries a difficulty of respiration arises; and from the quiescence of the other glands less bile, less gastric and pancreatic juice, are secreted into the stomach and intestines, and less mucus and saliva are poured into the mouth; whence arises the dry tongue, costiveness, dry ulcers, and paucity of urine. From the quiescence of the absorbent system arises the great thirst, as less moisture is absorbed from the atmosphere. The absorption from the atmosphere was observed by Dr. Lyster to amount to eighteen ounces in one night, above what he had at the same time insensibly perspired. See Langrish. On the same account the urine is pale, though in small quantity, for the thinner part is not absorbed from it; and when repeated ague-fits continue long, the legs swell from the diminished absorption of the cellular absorbents. From the quiescence of the intestinal canal a loss of appetite and flatulencies proceed. From the partial quiescence of the glandular viscera a swelling and tension about the præcordia becomes sensible to the touch; which is occasioned by the delay of the fluids from the defect of venous or lymphatic absorption. The pain of the forehead, and of the limbs, and of the small of the back, arises from the quiescence of the membranous fascia, or muscles of those parts, in the same manner as the skin becomes painful, when the vessels, of which it is composed, become quiescent from cold. The trembling in consequence of the pain of coldness, the restlessness, and the yawning, and stretching of the limbs, together with the shuddering, or rigours, are convulsive motions; and will be explained amongst the diseases of volition; Sect. XXXIV. Sickness and vomiting is a frequent symptom in the beginnings of fever-fits, the muscular fibres of the stomach share the general torpor and debility of the system; their motions become first lessened, and then stop, and then become retrograde; for the act of vomiting, like the globus hystericus and the borborigmi of hypochondriasis, is always a symptom of debility, either from want of stimulus, as in hunger; or from want of sensorial power, as after intoxication; or from sympathy with some other torpid irritative motions, as in the cold fits of ague. See Sect. XII. 5. 5. XXIX. 11. and XXXV. 1. 3. where this act of vomiting is further explained. The small pulse, which is said by some writers to be slow at the commencement of ague-fits, and which is frequently trembling and intermittent, is owing to the quiescence of the heart and arterial system, and to the resistance opposed to the circulating fluid from the inactivity of all the glands and capillaries. The great weakness and inability to voluntary motions, with the insensibility of the extremities, are owing to the general quiescence of the whole moving system; or, perhaps, simply to the deficient production of sensorial power. If all these symptoms are further increased, the quiescence of all the muscles, including the heart and arteries, becomes complete, and death ensues. This is, most probably, the case of those who are starved to death with cold, and of those who are said to die in Holland from long skaiting on their frozen canals. 2. As soon as this general quiescence of the system ceases, either by the diminution of the cause, or by the accumulation of sensorial power, (as in syncope, Sect. XII. 7. 1.) which is the natural consequence of previous quiescence, the hot fit commences. Every gland of the body is now stimulated into stronger action than is natural, as its irritability is increased by accumulation of sensorial power during its late quiescence, a superabundance of all the secretions is produced, and an increase of heat in consequence of the increase of these secretions. The skin becomes red, and the perspiration great, owing to the increased action of the capillaries during the hot part of the paroxysm. The secretion of perspirable matter is perhaps greater during the hot fit than in the sweating fit which follows; but as the absorption of it also is greater, it does not stand on the skin in visible drops: add to this, that the evaporation of it also is greater, from the increased heat of the skin. But at the decline of the hot fit, as the mouths of the absorbents of the skin are exposed to the cooler air, or bed-clothes, these vessels sooner lose their increased activity, and cease to absorb more than their natural quantity: but the secerning vessels for some time longer, being kept warm by the circulating blood, continue to pour out an increased quantity of perspirable matter, which now stands on the skin in large visible drops; the exhalation of it also being lessened by the greater coolness of the skin, as well as its absorption by the diminished action of the lymphatics. See Class I. 1. 2. 3. The increased secretion of bile and of other fluids poured into the intestines frequently induce a purging at the decline of the hot fit; for as the external absorbent vessels have their mouths exposed to the cold air, as above mentioned, they cease to be excited into unnatural activity sooner than the secretory vessels, whose mouths are exposed to the warmth of the blood: now, as the internal absorbents sympathize with the external ones, these also, which during the hot fit drank up the thinner part of the bile, or of other secreted fluids, lose their increased activity before the gland loses its increased activity, at the decline of the hot fit; and the loose dejections are produced from the same cause, that the increased perspiration stands on the surface of the skin, from the increased absorption ceasing sooner than the increased secretion. The urine during the cold fit is in small quantity and pale, both from a deficiency of the secretion and a deficiency of the absorption. During the hot fit it is in its usual quantity, but very high coloured and turbid, because a greater quantity had been secreted by the increased action of the kidnies, and also a greater quantity of its more aqueous part had been absorbed from it in the bladder by the increased action of the absorbents; and lastly, at the decline of the hot fit it is in large quantity and less coloured, or turbid, because the absorbent vessels of the bladder, as observed above, lose their increased action by sympathy with the cutaneous ones sooner than the secretory vessels of the kidnies lose their increased activity. Hence the quantity of the sediment, and the colour of the urine, in fevers, depend much on the quantity secreted by the kidnies, and the quantity absorbed from it again in the bladder: the kinds of sediment, as the lateritious, purulent, mucous, or bloody sediments, depend on other causes. It should be observed, that if the sweating be increased by the heat of the room, or of the bed-clothes, that a paucity of turbid urine will continue to be produced, as the absorbents of the bladder will have their activity increased by their sympathy with the vessels of the skin, for the purpose of supplying the fluid expended in perspiration. The pulse becomes strong and full owing to the increased irritability of the heart and arteries, from the accumulation of sensorial power during their quiescence, and to the quickness of the return of the blood from the various glands and capillaries. This increased action of all the secretory vessels does not occur very suddenly, nor universally at the same time. The heat seems to begin about the center, and to be diffused from thence irregularly to the other parts of the system. This may be owing to the situation of the parts which first became quiescent and caused the fever-fit, especially when a hardness or tumour about the præcordia can be felt by the hand; and hence this part, in whatever viscus it is seated, might be the first to regain its natural or increased irritability. 3. It must be here noted, that, by the increased quantity of heat, and of the impulse of the blood at the commencement of the hot fit, a great increase of stimulus is induced, and is now added to the increased irritability of the system, which was occasioned by its previous quiescence. This additional stimulus of heat and momentum of the blood augments the violence of the movements of the arterial and glandular system in an increasing ratio. These violent exertions still producing more heat and greater momentum of the moving fluids, till at length the sensoral power becomes wasted by this great stimulus beneath its natural quantity, and predisposes the system to a second cold fit. At length all these unnatural exertions spontaneously subside with the increased irritability that produced them; and which was itself produced by the preceding quiescence, in the same manner as the eye, on coming from darkness into day-light, in a little time ceases to be dazzled and pained, and gradually recovers its natural degree of irritability. 4. But if the increase of irritability, and the consequent increase of the stimulus of heat and momentum, produce more violent exertions than those above described; great pain arises in some part of the moving system, as in the membranes of the brain, pleura, or joints; and new motions of the vessels are produced in consequence of this pain, which are called inflammation; or delirium or stupor arises; as explained in Sect. XXI. and XXXIII.: for the immediate effect is the same, whether the great energy of the moving organs arises from an increase of stimulus or an increase of irritability; though in the former case the waste of sensorial power leads to debility, and in the latter to health. _Recapitulation._ X. Those muscles, which are less frequently exerted, and whose actions are interrupted by sleep, acquire less accumulation of sensorial power during their quiescent state, as the muscles of locomotion. In these muscles after great exertion, that is, after great exhaustion of sensorial power, the pain of fatigue ensues; and during rest there is a renovation of the natural quantity of sensorial power; but where the rest, or quiescence of the muscle, is long continued, a quantity of sensorial power becomes accumulated beyond what is necessary; as appears by the uneasiness occasioned by want of exercise; and which in young animals is one cause exciting them into action, as is seen in the play of puppies and kittens. But when those muscles, which are habituated to perpetual actions, as those of the stomach by the stimulus of food, those of the vessels of the skin by the stimulus of heat, and those which constitute the arteries and glands by the stimulus of the blood, become for a time quiescent, from the want of their appropriated stimuli, or by their associations with other quiescent parts of the system; a greater accumulation of sensorial power is acquired during their quiescence, and a greater or quicker exhaustion of it is produced during their increased action. This accumulation of sensorial power from deficient action, if it happens to the stomach from want of food, occasions the pain of hunger; if it happens to the vessels of the skin from want of heat, it occasions the pain of cold; and if to the arterial system from the want of its adapted stimuli, many disagreeable sensations are occasioned, such as are experienced in the cold fits of intermittent fevers, and are as various, as there are glands or membranes in the system, and are generally termed universal uneasiness. When the quiescence of the arterial system is not owing to defect of stimulus as above, but to the defective quantity of sensorial power, as in the commencement of nervous fever, or irritative fever with weak pulse, a great torpor of this system is quickly induced; because both the irritation from the stimulus of the blood, and the association of the vascular motions with each other, continue to excite the arteries into action, and thence quickly exhaust the ill-supplied vascular muscles; for to rest is death; and therefore those vascular muscles continue to proceed, though with feebler action, to the extreme of weariness or faintness: while nothing similar to this affects the locomotive muscles, whose actions are generally caused by volition, and not much subject either to irritation or to other kinds of associations besides the voluntary ones, except indeed when they are excited by the lash of slavery. In these vascular muscles, which are subject to perpetual action, and thence liable to great accumulation of sensorial power during their quiescence from want of stimulus, a great increase of activity occurs, either from the renewal of their accustomed stimulus, or even from much less quantities of stimulus than usual. This increase of action constitutes the hot fit of fever, which is attended with various increased secretions, with great concomitant heat, and general uneasiness. The uneasiness attending this hot paroxysm of fever, or fit of exertion, is very different from that, which attends the previous cold fit, or fit of quiescence, and is frequently the cause of inflammation, as in pleurisy, which is treated of in the next section. A similar effect occurs after the quiescence of our organs of sense; those which are not subject to perpetual action, as the taste and smell, are less liable to an exuberant accumulation of sensorial power after their having for a time been inactive; but the eye, which is in perpetual action during the day, becomes dazzled, and liable to inflammation after a temporary quiescence. Where the previous quiescence has been owing to a defect of sensorial power, and not to a defect of stimulus, as in the irritative fever with weak pulse, a similar increase of activity of the arterial system succeeds, either from the usual stimulus of the blood, or from a stimulus less than usual; but as there is in general in these cases of fever with weak pulse a deficiency of the quantity of the blood, the pulse in the hot fit is weaker than in health, though it is stronger than in the cold fit, as explained in No. 2. of this section. But at the same time in those fevers, where the defect of irritation is owing to the defect of the quantity of sensorial power, as well as to the defect of stimulus, another circumstance occurs; which consists in the partial distribution of it, as appears in partial flushings, as of the face or bosom, while the extremities are cold; and in the increase of particular secretions, as of bile, saliva, insensible perspiration, with great heat of the skin, or with partial sweats, or diarrhoea. There are also many uneasy sensations attending these increased actions, which, like those belonging to the hot fit of fever with strong pulse, are frequently followed by inflammation, as in scarlet fever; which inflammation is nevertheless accompanied with a pulse weaker, though quicker, than the pulse during the remission or intermission of the paroxysms, though stronger than that of the previous cold fit. From hence I conclude, that both the cold and hot fits of fever are necessary consequences of the perpetual and incessant action of the arterial and glandular system; since those muscular fibres and those organs of sense, which are most frequently exerted, become necessarily most affected both with defect and accumulation of sensorial power: and that hence _fever-fits are not an effort of nature to relieve herself_, and that therefore they should always be prevented or diminished as much as possible, by any means which decrease the general or partial vascular actions, when they are greater, or by increasing them when they are less than in health, as described in Sect. XII. 6. 1. Thus have I endeavoured to explain, and I hope to the satisfaction of the candid and patient reader, the principal symptoms or circumstances of fever without the introduction of the supernatural power of spasm. To the arguments in favour of the doctrine of spasm it may be sufficient to reply, that in the evolution of medical as well as of dramatic catastrophe, Nec Deus intersit, nisi dignus vindice nodus inciderit.--HOR. * * * * * SECT. XXXIII. DISEASES OF SENSATION. I. 1. _Motions excited by sensation. Digestion. Generation. Pleasure of existence. Hypochondriacism._ 2. _Pain introduced. Sensitive fevers of two kinds._ 3. _Two sensorial powers exerted in sensitive fevers. Size of the blood. Nervous fevers distinguished from putrid ones. The septic and antiseptic theory._ 4. _Two kinds of delirium._ 5. _Other animals are less liable to delirium, cannot receive our contagious diseases, and are less liable to madness._ II. 1. _Sensitive motions generated._ 2. _Inflammation explained._ 3. _Its remote causes from excess of irritation, or of irritability, not from those pains which are owing to defect of irritation. New vessels produced, and much heat._ 4. _Purulent matter secreted._ 5. _Contagion explained._ 6. _Received but once._ 7. _If common matter be contagious?_ 8. _Why some contagions are received but once._ 9. _Why others may be received frequently. Contagions of small-pox and measles do not act at the same times. Two cases of such patients._ 10. _The blood from patients in the small-pox will not infect others. Cases of children thus inoculated. The variolous contagion is not received into the blood. It acts by sensitive association between the stomach and skin._ III. 1. _Absorption of solids and fluids._ 2. _Art of healing ulcers._ 3. _Mortification attended with less pain in weak people._ I. 1. As many motions of the body are excited and continued by irritations, so others require, either conjunctly with these, or separately, the pleasurable or painful sensations, for the purpose of producing them with due energy. Amongst these the business of digestion supplies us with an instance: if the food, which we swallow, is not attended with agreeable sensation, it digests less perfectly; and if very disagreeable sensation accompanies it, such as a nauseous idea, or very disgustful taste, the digestion becomes impeded; or retrograde motions of the stomach and oesophagus succeed, and the food is ejected. The business of generation depends so much on agreeable sensation, that, where the object is disgustful, neither voluntary exertion nor irritation can effect the purpose; which is also liable to be interrupted by the pain of fear or bashfulness. Besides the pleasure, which attends the irritations produced by the objects of lust and hunger, there seems to be a sum of pleasurable affection accompanying the various secretions of the numerous glands, which constitute the pleasure of life, in contradistinction to the tedium vitæ. This quantity or sum of pleasurable affection, seems to contribute to the due or energetic performance of the whole moveable system, as well that of the heart and arteries, as of digestion and of absorption; since without the due quantity of pleasurable sensation, flatulency and hypochondriacism affect the intestines, and a languor seizes the arterial pulsations and secretions; as occurs in great and continued anxiety of the mind. 2. Besides the febrile motions occasioned by irritation, described in Sect. XXXII. and termed irritative fever, it frequently happens that pain is excited by the violence of the fibrous contractions; and other new motions are then superadded, in consequence of sensation, which we shall term febris sensitiva, or sensitive fever. It must be observed, that most irritative fevers begin with a decreased exertion of irritation, owing to defect of stimulus; but that on the contrary the sensitive fevers, or inflammations, generally begin with the increased exertion of sensation, as mentioned in Sect. XXXI. on temperaments: for though the cold fit, which introduces inflammation, commences with decreased irritation, yet the inflammation itself commences in the hot fit during the increase of sensation. Thus a common pustule, or phlegmon, in a part of little sensibility does not excite an inflammatory fever; but if the stomach, intestines, or the tender substance beneath the nails, be injured, great sensation is produced, and the whole system is thrown into that kind of exertion, which constitutes inflammation. These sensitive fevers, like the irritative ones, resolve themselves into those with arterial strength, and those with arterial debility, that is with excess or defect of sensorial power; these may be termed the febris sensitiva pulsu forti, sensitive fever with strong pulse, which is the synocha, or inflammatory fever; and the febris sensitiva pulsu debili, sensitive fever with weak pulse, which is the typhus gravior, or putrid fever of some writers. 3. The inflammatory fevers, which are here termed sensitive fevers with strong pulse, are generally attended with some topical inflammation, as pleurisy, peripneumony, or rheumatism, which distinguishes them from irritative fevers with strong pulse. The pulse is strong, quick, and full; for in this fever there is great irritation, as well as great sensation, employed in moving the arterial system. The size, or coagulable lymph, which appears on the blood, is probably an increased secretion from the inflamed internal lining of the whole arterial system, the thinner part being taken away by the increased absorption of the inflamed lymphatics. The sensitive fevers with weak pulse, which are termed putrid or malignant fevers, are distinguished from irritative fevers with weak pulse, called nervous fevers, described in the last section, as the former consist of inflammation joined with debility, and the latter of debility alone. Hence there is greater heat and more florid colour of the skin in the former, with petechiæ, or purple spots, and aphthæ, or sloughs in the throat, and generally with previous contagion. When animal matter dies, as a slough in the throat, or the mortified part of a carbuncle, if it be kept moist and warm, as during its abhesion to a living body, it will soon putrify. This, and the origin of contagion from putrid animal substances, seem to have given rise to the septic and antiseptic theory of these fevers. The matter in pustules and ulcers is thus liable to become putrid, and to produce microscopic animalcula; the urine, if too long retained, may also gain a putrescent smell, as well as the alvine feces; but some writers have gone so far as to believe, that the blood itself in these fevers has smelt putrid, when drawn from the arm of the patient: but this seems not well founded; since a single particle of putrid matter taken into the blood can produce fever, how can we conceive that the whole mass could continue a minute in a putrid state without destroying life? Add to this, that putrid animal substances give up air, as in gangrenes; and that hence if the blood was putrid, air should be given out, which in the blood-vessels is known to occasion immediate death. In these sensitive fevers with strong pulse (or inflammations) there are two sensorial faculties concerned in producing the disease, viz. irritation and sensation; and hence, as their combined action is more violent, the general quantity of sensorial power becomes further exhausted during the exacerbation, and the system more rapidly weakened than in irritative fever with strong pulse; where the spirit of animation is weakened by but one mode of its exertion: so that this febris sensitiva pulsu forti (or inflammatory fever,) may be considered as the febris irritativa pulsu forti, with the addition of inflammation; and the febris sensitiva pulsu debili (or malignant fever) may be considered as the febris irritativa pulsu debili (or nervous fever), with the addition of inflammation. 4. In these putrid or malignant fevers a deficiency of irritability accompanies the increase of sensibility; and by this waste of sensorial power by the excess of sensation, which was already too small, arises the delirium and stupor which so perpetually attend these inflammatory fevers with arterial debility. In these cases the voluntary power first ceases to act from deficiency of sensorial spirit; and the stimuli from external bodies have no effect on the exhausted sensorial power, and a delirium like a dream is the consequence. At length the internal stimuli cease to excite sufficient irritation, and the secretions are either not produced at all, or too parsimonious in quantity. Amongst these the secretion of the brain, or production of the sensorial power, becomes deficient, till at last all sensorial power ceases, except what is just necessary to perform the vital motions, and a stupor succeeds; which is thus owing to the same cause as the preceding delirium exerted in a greater degree. This kind of delirium is owing to a suspension of volition, and to the disobedience of the senses to external stimuli, and is always occasioned by great debility, or paucity of sensorial power; it is therefore a bad sign at the end of inflammatory fevers, which had previous arterial strength, as rheumatism, or pleurisy, as it shews the presence of great exhaustion of sensorial power in a system, which having lately been exposed to great excitement, is not so liable to be stimulated into its healthy action, either by additional stimulus of food and medicines, or by the accumulation of sensorial power during its present torpor. In inflammatory fevers with debility, as those termed putrid fevers, delirium is sometimes, as well as stupor, rather a favourable sign; as less sensorial power is wasted during its continuance (see Class II. 1. 6. 8.), and the constitution not having been previously exposed to excess of stimulation, is more liable to be excited after previous quiescence. When the sum of general pleasurable sensation becomes too great, another kind of delirium supervenes, and the ideas thus excited are mistaken for the irritations of external objects: such a delirium is produced for a time by intoxicating drugs, as fermented liquors, or opium: a permanent delirium of this kind is sometimes induced by the pleasures of inordinate vanity, or by the enthusiastic hopes of heaven. In these cases the power of volition is incapable of exertion, and in a great degree the external senses become incapable of perceiving their adapted stimuli, because the whole sensorial power is employed or expended on the ideas excited by pleasurable sensation. This kind of delirium is distinguished from that which attends the fevers above mentioned from its not being accompanied with general debility, but simply with excess of pleasurable sensation; and is therefore in some measure allied to madness or to reverie; it differs from the delirium of dreams, as in this the power of volition is not totally suspended, nor are the senses precluded from external stimulation; there is therefore a degree of consistency, in this kind of delirium, and a degree of attention to external objects, neither of which exist in the delirium of fevers or in dreams. 5. It would appear, that the vascular system of other animals are less liable to be put into action by their general sum of pleasurable or painful sensation; and that the trains of their ideas, and the muscular motions usually associated with them, are less powerfully connected than in the human system. For other animals neither weep, nor smile, nor laugh; and are hence seldom subject to delirium, as treated of in Sect. XVI. on Instinct. Now as our epidemic and contagious diseases are probably produced by disagreeable sensation, and not simply by irritation; there appears a reason, why brute animals are less liable to epidemic or contagious diseases; and secondly, why none of our contagions, as the small-pox or measles, can be communicated to them, though one of theirs, viz. the hydrophobia, as well as many of their poisons, as those of snakes and of in insects, communicate their deleterious or painful effects to mankind. Where the quantity of general painful sensation is too great in the system, inordinate voluntary exertions are produced either of our ideas, as in melancholy and madness, or of our muscles, as in convulsion. From these maladies also brute animals are much more exempt than mankind, owing to their greater inaptitude to voluntary exertion, as mentioned in Sect. XVI. on Instinct. II. 1. When any moving organ is excited into such violent motions, that a quantity of pleasurable or painful sensation is produced, it frequently happens (but not always) that new motions of the affected organ are generated in consequence of the pain or pleasure, which are termed inflammation. These new motions are of a peculiar kind, tending to distend the old, and to produce new fibres, and thence to elongate the straight muscles, which serve locomotion, and to form new vessels at the extremities or sides of the vascular muscles. 2. Thus the pleasurable sensations produce an enlargement of the nipples of nurses, of the papillæ of the tongue, of the penis, and probably produce the growth of the body from its embryon state to its maturity; whilst the new motions in consequence of painful sensation, with the growth of the fibres or vessels, which they occasion, are termed inflammation. Hence when the straight muscles are inflamed, part of their tendons at each extremity gain new life and sensibility, and thus the muscle is for a time elongated; and inflamed bones become soft, vascular, and sensible. Thus new vessels shoot over the cornea of inflamed eyes, and into scirrhous tumours, when they become inflamed; and hence all inflamed parts grow together by intermixture, and inosculation of the new and old vessels. The heat is occasioned from the increased secretions either of mucus, or of the fibres, which produce or elongate the vessels. The red colour is owing to the pellucidity of the newly formed vessels, and as the arterial parts of them are probably formed before their correspondent venous parts. 3. These new motions are excited either from the increased quantity of sensation in consequence of greater fibrous contractions, or from increased sensibility, that is, from the increased quantity of sensorial power in the moving organ. Hence they are induced by great external stimuli, as by wounds, broken bones; and by acrid or infectious materials; or by common stimuli on those organs, which have been some time quiescent; as the usual light of the day inflames the eyes of those, who have been confined in dungeons; and the warmth of a common fire inflames those, who have been previously exposed to much cold. But these new motions are never generated by that pain, which arises from defect of stimulus, as from hunger, thirst, cold, or inanition, with all those pains, which are termed nervous. Where these pains exist, the motions of the affected part are lessened; and if inflammation succeeds, it is in some distant parts; as coughs are caused by coldness and moisture being long applied to the feet; or it is in consequence of the renewal of the stimulus, as of heat or food, which excites our organs into stronger action after their temporary quiescence; as kibed heels after walking in snow. 4. But when these new motions of the vascular muscles are exerted with greater violence, and these vessels are either elongated too much or too hastily, a new material is secreted from their extremities, which is of various kinds according to the peculiar animal motions of this new kind of gland, which secretes it; such is the pus laudabile or common matter, the variolous matter, venereal matter, catarrhous matter, and many others. 5. These matters are the product of an animal process; they are secreted or produced from the blood by certain diseased motions of the extremities of the blood-vessels, and are on that account all of them contagious; for if a portion of any of these matters is transmitted into the circulation, or perhaps only inserted into the skin, or beneath the cuticle of an healthy person, its stimulus in a certain time produces the same kind of morbid motions, by which itself was produced; and hence a similar kind is generated. See Sect. XXXIX. 6. 1. 6. It is remarkable, that many of these contagious matters are capable of producing a similar disease but once; as the small-pox and measles; and I suppose this is true of all those contagious diseases, which are spontaneously cured by nature in a certain time; for if the body was capable of receiving the disease a second time, the patient must perpetually infect himself by the very matter, which he has himself produced, and is lodged about him; and hence he could never become free from the disease. Something similar to this is seen in the secondary fever of the confluent small-pox; there is a great absorption of variolous matter, a very minute part of which would give the genuine small-pox to another person; but here it only stimulates the system into common fever; like that which common puss, or any other acrid material might occasion. 7. In the pulmonary consumption, where common matter is daily absorbed, an irritative fever only, without new inflammation, is generally produced; which is terminated like other irritative fevers by sweats, or loose stools. Hence it does not appear, that this absorbed matter always acts as a contagious material producing fresh inflammation or new abscesses. Though there is reason to believe, that the first time any common matter is absorbed, it has this effect, but not the second time, like the variolous matter above mentioned. This accounts for the opinion, that the pulmonary consumption is sometimes infectious, which opinion was held by the ancients, and continues in Italy at present; and I have myself seen three or four instances, where a husband and wife, who have slept together, and have thus much received each other's breath, who have infected each other, and both died in consequence of the original taint of only one of them. This also accounts for the abscesses in various parts of the body, that are sometimes produced after the inoculated small-pox is terminated; for this second absorption of variolous matter acts like common matter, and produces only irritative fever in those children, whose constitutions have already experienced the absorption of common matter; and inflammation with a tendency to produce new abscesses in those, whose constitutions have not experienced the absorptions of common matter. It is probable, that more certain proofs might have been found to shew, that common matter is infectious the first time it is absorbed, tending to produce similar abscesses, but not the second time of its absorption, if this subject had been attended to. 8. These contagious diseases are very numerous, as the plague, small-pox, chicken-pox, measles, scarlet-fever, pemphigus, catarrh, chincough, venereal disease, itch, trichoma, tinea. The infectious material does not seem to be dissolved by the air, but only mixed with it perhaps in fine powder, which soon subsides; since many of these contagions can only be received by actual contact; and others of them only at small distances from the infected person; as is evident from many persons having been near patients of the small-pox without acquiring the disease. The reason, why many of these diseases are received but once, and others repeatedly, is not well understood; it appears to me, that the constitution becomes so accustomed to the stimuli of these infectious materials, by having once experienced them, that though irritative motions, as hectic fevers, may again be produced by them, yet no sensation, and in consequence no general inflammation succeeds; as disagreeable smells or tastes by habit cease to be perceived; they continue indeed to excite irritative ideas on the organs of sense, but these are not succeeded by sensation. There are many irritative motions, which were at first succeeded by sensation, but which by frequent repetition cease to excite sensation, as explained in Sect. XX. on Vertigo. And, that this circumstance exists in respect to infectious matter appears from a known fact; that nurses, who have had the small-pox, are liable to experience small ulcers on their arms by the contact of variolous matter in lifting their patients; and that when patients, who have formerly had the small-pox have been inoculated in the arm, a phlegmon, or inflamed sore, has succeeded, but no subsequent fever. Which shews, that the contagious matter of the small-pox has not lost its power of stimulating the part it is applied to, but that the general system is not affected in consequence. See Section XII. 7. 6. XIX. 9. 9. From the accounts of the plague, virulent catarrh, and putrid dysentery, it seems uncertain, whether these diseases are experienced more than once; but the venereal disease and itch are doubtless repeatedly infectious; and as these diseases are never cured spontaneously, but require medicines, which act without apparent operation, some have suspected, that the contagious material produces similar matter rather by a chemical change of the fluids, than by an animal process; and that the specific medicines destroy their virus by chemically combining with it. This opinion is successfully combated by Mr. Hunter, in his Treatise on Venereal Disease, Part I. c. i. But this opinion wants the support of analogy, as there is no known process in animal bodies, which is purely chemical, not even digestion; nor can any of these matters be produced by chemical processes. Add to this, that it is probable, that the insects, observed in the pustules of the itch, and in the stools of dysenteric patients, are the consequences, and not the causes of these diseases. And that the specific medicines, which cure the itch and lues venerea, as brimstone and mercury, act only by increasing the absorption of the matter in the ulcuscles of those diseases, and thence disposing them to heal; which would otherwise continue to spread. Why the venereal disease, and itch, and tenia, or scald head, are repeatedly contagious, while those contagions attended with fever can be received but once, seems to depend on their being rather local diseases than universal ones, and are hence not attended with fever, except the purulent fever in their last stages, when the patient is destroyed by them. On this account the whole of the system does not become habituated to these morbid actions, so as to cease to be affected with sensation by a repetition of the contagion. Thus the contagious matter of the venereal disease, and of the tenia, affects the lymphatic glands, as the inquinal glands, and those about the roots of the hair and neck, where it is arrested, but does not seem to affect the blood-vessels, since no fever ensues. Hence it would appear, that these kinds of contagion are propagated not by means of the circulation, but by sympathy of distant parts with each other; since if a distant part, as the palate, should be excited by sensitive association into the same kind of motions, as the parts originally affected by the contact of infectious matter; that distant part will produce the same kind of infectious matter; for every secretion from the blood is formed from it by the peculiar motions of the fine extremities of the gland, which secretes it; the various secreted fluids, as the bile, saliva, gastric juice, not previously existing, as such, in the blood-vessels. And this peculiar sympathy between the genitals and the throat, owing to sensitive association, appears not only in the production of venereal ulcers in the throat, but in variety of other instances, as in the mumps, in the hydrophobia, some coughs, strangulation, the production of the beard, change of voice at puberty. Which are further described in Class IV. 1. 2. 7. To evince that the production of such large quantities of contagious matter, as are seen in some variolous patients, so as to cover the whole skin almost with pustules, does not arise from any chemical fermentation in the blood, but that it is owing to morbid motions of the fine extremities of the capillaries, or glands, whether these be ruptured or not, appears from the quantity of this matter always corresponding with the quantity of the fever; that is, with the violent exertions of those glands and capillaries, which are the terminations of the arterial system. The truth of this theory is evinced further by a circumstance observed by Mr. J. Hunter, in his Treatise on Venereal Disease; that in a patient, who was inoculated for the small-pox, and who appeared afterwards to have been previously infested with the measles, the progress of the small-pox was delayed till the measles had run their course, and that then the small-pox went through its usual periods. Two similar cases fell under my care, which I shall here relate, as it confirms that of Mr. Hunter, and contributes to illustrate this part of the theory of contagious diseases. I have transcribed the particulars from a letter of Mr. Lightwood of Yoxal, the surgeon who daily attended them, and at my request, after I had seen them, kept a kind of journal of their cases. Miss H. and Miss L. two sisters, the one about four and the other about three years old, were inoculated Feb. 7, 1791. On the 10th there was a redness on both arms discernible by a glass. On the 11th their arms were so much inflamed as to leave no doubt of the infection having taken place. On the 12th less appearance of inflammation on their arms. In the evening Miss L. had an eruption, which resembled the measles. On the 12th the eruption on Miss L. was very full on the face and breast, like the measles, with considerable fever. It was now known, that the measles were in a farm house in the neighbourhood. Miss H.'s arm less inflamed than yesterday. On the 14th Miss L.'s fever great, and the eruption universal. The arm appears to be healed. Miss H.'s arm somewhat redder. They were now put into separate rooms. On the 15th Miss L.'s arms as yesterday. Eruption continues. Miss H.'s arms have varied but little. 16th, the eruptions on Miss L. are dying away, her fever gone. Begins to have a little redness in one arm at the place of inoculation. Miss H.'s arms get redder, but she has no appearance of complaint. 20th, Miss L.'s arms have advanced slowly till this day, and now a few pustules appear. Miss H.'s arm has made little progress from the 16th to this day, and now she has some fever. 21st, Miss L. as yesterday. Miss H. has much inflammation, and an increase of the red circle on one arm to the size of half a crown, and had much fever at night, with fetid breath. 22d, Miss L.'s pustules continue advancing. Miss H.'s inflammation of her arm and red circle increases. A few red spots appear in different parts with some degree of fever this morning, 23d. Miss L. has a larger crop of pustules. Miss H. has small pustules and great inflammation of her arms, with but one pustule likely to suppurate. After this day they gradually got well, and the pustules disappeared. In one of these cases the measles went through their common course with milder symptoms than usual, and in the other the measly contagion seemed just sufficient to stop the progress of variolous contagion, but without itself throwing the constitution into any disorder. At the same time both the measles and small-pox seem to have been rendered milder. Does not this give an idea, that if they were both inoculated at the same time, that neither of them might affect the patient? From these cases I contend, that the contagious matter of these diseases does not affect the constitution by a fermentation, or chemical change of the blood, because then they must have proceeded together, and have produced a third something, not exactly similar to either of them: but that they produce new motions of the cutaneous terminations of the blood-vessels, which for a time proceed daily with increasing activity, like some paroxysms of fever, till they at length secrete or form a similar poison by these unnatural actions. Now as in the measles one kind of unnatural motion takes place, and in the small-pox another kind, it is easy to conceive, that these different kinds of morbid motions cannot exist together; and therefore, that that which has first begun will continue till the system becomes habituated to the stimulus which occasions it, and has ceased to be thrown into action by it; and then the other kind of stimulus will in its turn produce fever, and new kinds of motions peculiar to itself. 10. On further considering the action of contagious matter, since the former part of this work was sent to the press; where I have asserted, in Sect. XXII. 3. 3. that it is probable, that the variolous matter is diffused through the blood; I prevailed on my friend Mr. Power, surgeon at Bosworth in Leicestershire to try, whether the small-pox could be inoculated by using the blood of a variolous patient instead of the matter from the pustules; as I thought such an experiment might throw some light at least on this interesting subject. The following is an extract from his letter:-- "March 11, 1793. I inoculated two children, who had not had the small-pox, with blood; which was taken from a patient on the second day after the eruption commenced, and before it was completed. And at the same time I inoculated myself with blood from the same person, in order to compare the appearances, which might arise in a person liable to receive the infection, and in one not liable to receive it. On the same day I inoculated four other children liable to receive the infection with blood taken from another person on the fourth day after the commencement of the eruption. The patients from whom the blood was taken had the disease mildly, but had the most pustules of any I could select from twenty inoculated patients; and as much of the blood was insinuated under the cuticle as I could introduce by elevating the skin without drawing blood; and three or four such punctures were made in each of their arms, and the blood was used in its fluid state. "As the appearances in all these patients, as well as in myself, were similar, I shall only mention them in general terms. March 13. A slight subcuticular discoloration, with rather a livid appearance, without soreness or pain, was visible in them all, as well as in my own hand. 15. The discoloration somewhat less, without pain or soreness. Some patients inoculated on the same day with variolous matter have considerable inflammation. 17. The discoloration is quite gone in them all, and from my own hand, a dry mark only remaining. And they were all inoculated on the 18th, with variolous matter, which produced the disease in them all." Mr. Power afterwards observes, that, as the patients from whom the blood was taken had the disease mildly, it may be supposed, that though the contagious matter might be mixed with the blood, it might still be in too dilute a state to convey the infection; but adds at the same time, that he has diluted recent matter with at least five times its quantity of water, and which has still given the infection; though he has sometimes diluted it so far as to fail. The following experiments were instituted at my request by my friend Mr. Hadley, surgeon in Derby, to ascertain whether the blood of a person in the small-pox be capable of communicating the disease. "Experiment 1st. October 18th, 1793. I took some blood from a vein in the arm of a person who had the small-pox, on the second day of the eruption, and introduced a small quantity of it immediately with the point of a lancet between the scars and true skin of the right arm of a boy nine years old in two or three different places; the other arm was inoculated with variolous matter at the same time. "19th. The punctured parts of the right arm were surrounded with some degree of subcuticular inflammation. 20th. The inflammation more considerable, with a slight degree of itching, but no pain upon pressure. 21st. Upon examining the arm this day with a lens I found the inflammation less extensive, and the redness changing to a deep yellow or orange-colour, 22d. Inflammation nearly gone. 23d. Nothing remained, except a slight discoloration and a little scurfy appearance on the punctures. At the same time the inflammation of the arm inoculated with variolous matter was increasing fast, and he had the disease mildly at the usual time. "Experiment 2d. I inoculated another child at the same time and in the same manner, with blood taken on the first day of the eruption; but as the appearance and effects were similar to those in the preceding experiment, I shall not relate them minutely. "Experiment 3d. October 20th. Blood was taken from a person who had the small-pox, on the third day of the eruption, and on the sixth from the commencement of the eruptive fever. I introduced some of it in its fluid state into both arms of a boy seven years old. 21st. There appeared to be some inflammation under the cuticle, where the punctures were made. 22d. Inflammation more considerable. 23d. On this day the inflammation was somewhat greater, and the cuticle rather elevated. "24th. Inflammation much less, and only a brown or orange-colour remained. 25th. Scarcely any discoloration left. On this day he was inoculated with variolous matter, the progress of the infection went on in the usual way, and he had the small-pox very favourably. "At this time I was requested to inoculate a young person, who was thought to have had the small-pox, but his parents were not quite certain; in one arm I introduced variolous matter, and in the other blood, taken as in experiment 3d. On the second day after the operation, the punctured parts were inflamed, though I think the arm in which I had inserted variolous matter was rather more so than the other. On the third the inflammation was increased, and looked much the same as in the preceding experiment. 4th. The inflammation was much diminished, and on the 5th almost gone. He was exposed at the same time to the natural infection, but has continued perfectly well. "I have frequently observed (and believe most practitioners have done the same), that if variolous matter be inserted in the arm of a person who has previously had the small-pox, that the inflammation on the second or third days is much greater, than if they had not had the disease, but on the fourth or fifth it disappears. "On the 23d I introduced blood into the arms of three more children, taken on the third and fourth days of the eruption. The appearances were much the same as mentioned in experiments first and third. They were afterwards inoculated with variolous matter, and had the disease in the regular way. "The above experiments were made with blood taken from a small vein in the hand or foot of three or four different patients, whom I had at that time under inoculation. They were selected from 160, as having the greatest number of pustules. The part was washed with warm water before the blood was taken, to prevent the possibility of any matter being mixed with it from the surface." Shall we conclude from hence, that the variolous matter never enters the blood-vessels? but that the morbid motions of the vessels of the skin around the insertion of it continue to increase in a larger and larger circle for six or seven days; that then their quantity of morbid action becomes great enough to produce a fever-fit, and to affect the stomach by association of motions? and finally, that a second association of motions is produced between the stomach and the other parts of the skin, inducing them into morbid actions similar to those of the circle round the insertion of the variolous matter? Many more experiments and observations are required before this important question can be satisfactorily answered. It may be adduced, that as the matter inserted into the skin of the arm frequently swells the lymphatic in the axilla, that in that circumstance it seems to be there arrested in its progress, and cannot be imagined to enter the blood by that lymphatic gland till the swelling of it subsides. Some other phænomena of the disease are more easily reconcileable to this theory of sympathetic motions than to that of absorption; as the time taken up between the insertion of the matter, and the operation of it on the system, as mentioned above. For the circle around the insertion is seen to increase, and to inflame; and I believe, undergoes a kind of diurnal paroxysm of torpor and paleness with a succeeding increase of action and colour, like a topical fever-fit. Whereas if the matter is conceived to circulate for six or seven days with the blood, without producing disorder, it ought to be rendered milder, or the blood-vessels more familiarized to its acrimony. It is much easier to conceive from this doctrine of associated or sympathetic motions of distant parts of the system, how it happens, that the variolous infection can be received but once, as before explained; than by supposing, that a change is effected in the mass of blood by any kind of fermentative process. The curious circumstance of the two contagions of small-pox and measles not acting at the same time, but one of them resting or suspending its action till that of the other ceases, may be much easier explained from sympathetic or associated actions of the infected part with other parts of the system, than it can from supposing the two contagions to enter the circulation. The skin of the face is subject to more frequent vicissitudes of heat and cold, from its exposure to the open air, and is in consequence more liable to sensitive association with the stomach than any other part of the surface of the body, because their actions have been more frequently thus associated. Thus in a surfeit from drinking cold water, when a person is very hot and fatigued, an eruption is liable to appear on the face in consequence of this sympathy. In the same manner the rosy eruption on the faces of drunkards more probably arises from the sympathy of the face with the stomach, rather than between the face and the liver, as is generally supposed. This sympathy between the stomach and the skin of the face is apparent in the eruption of the small-pox; since, where the disease is in considerable quantity, the eruption on the face first succeeds the sickness of the stomach. In the natural disease the stomach seems to be frequently primarily affected, either alone or along with the tonsils, as the matter seems to be only diffused in the air, and by being mixed with the saliva, or mucus of the tonsils, to be swallowed into the stomach. After some days the irritative circles of motions become disordered by this new stimulus, which acts upon the mucus lining of the stomach; and sickness, vertigo, and a diurnal fever succeed. These disordered irritative motions become daily increased for two or three days, and then by their increased action certain sensitive motions, or inflammation, is produced, and at the next cold fit of fever, when the stomach recovers from its torpor, an inflammation of the external skin is formed in points (which afterwards suppurate), by sensitive association, in the same manner as a cough is produced in consequence of exposing the feet to cold, as described in Sect. XXV. 17. and Class IV. 2. I. 7. If the inoculated skin of the arm, as far as it appears inflamed, was to be cut out, or destroyed by caustic, before the fever commenced, as suppose on the fourth day after inoculation, would this prevent the disease? as it is supposed to prevent the hydrophobia. III. 1. Where the new vessels, and enlarged old ones, which constitute inflammation, are not so hastily distended as to burst, and form a new kind of gland for the secretion of matter, as above mentioned; if such circumstances happen as diminish the painful sensation, the tendency to growth ceases, and by and by an absorption commences, not only of the superabundant quantity of fluids deposited in the inflamed part, but of the solids likewise, and this even of the hardest kind. Thus during the growth of the second set of teeth in children, the roots of the first set are totally absorbed, till at length nothing of them remains but the crown; though a few weeks before, if they are drawn immaturely, their roots are found complete. Similar to this Mr. Hunter has observed, that where a dead piece of bone is to exfoliate, or to separate from a living one, that the dead part does not putrify, but remains perfectly sound, while the surface of the living part of the bone, which is in contact with the dead part, becomes absorbed, and thus effects its separation. Med. Comment. Edinb. V. 1. 425. In the same manner the calcareous matter of gouty concretions, the coagulable lymph deposited on inflamed membranes in rheumatism and extravasated blood become absorbed; which are all as solid and as indissoluble materials as the new vessels produced in inflammation. This absorption of the new vessels and deposited fluids of inflamed parts is called resolution: it is produced by first using such internal means as decrease the pain of the part, and in consequence its new motions, as repeated bleeding, cathartics, diluent potations, and warm bath. After the vessels are thus emptied, and the absorption of the new vessels and deposited fluids is evidently begun, it is much promoted by stimulating the part externally by solutions of lead, or other metals, and internally by the bark, and small doses of opium. Hence when an ophthalmy begins to become paler, any acrid eye-water, as a solution of six grains of white vitriol in an ounce of water, hastens the absorption, and clears the eye in a very short time. But the same application used a few days sooner would have increased the inflammation. Hence after evacuation opium in small doses may contribute to promote the absorption of fluids deposited on the brain, as observed by Mr. Bromfield in his treatise of surgery. 2. Where an abscess is formed by the rupture of these new vessels, the violence of inflammation ceases, and a new gland separates a material called pus: at the same time a less degree of inflammation produces new vessels called vulgarly proud flesh; which, if no bandage confines its growth, nor any other circumstance promotes absorption in the wound, would rise to a great height above the usual size of the part. Hence the art of healing ulcers consists in producing a tendency to absorption in the wound greater than the deposition. Thus when an ill-conditioned ulcer separates a copious and thin discharge, by the use of any stimulus, as of salts of lead, or mercury, or copper externally applied, the discharge becomes diminished in quantity, and becomes thicker, as the thinner parts are first absorbed. But nothing so much contributes to increase the absorption in a wound as covering the whole limb above the sore with a bandage, which should be spread with some plaster, as with emplastrum de minio, to prevent it from slipping. By this artificial tightness of the skin, the arterial pulsations act with double their usual power in promoting the ascending current of the fluid in the valvular lymphatics. Internally the absorption from ulcers should be promoted first by evacuation, then by opium, bark, mercury, steel. 3. Where the inflammation proceeds with greater violence or rapidity, that is, when by the painful sensation a more inordinate activity of the organ is produced, and by this great activity an additional quantity of painful sensation follows in an increasing ratio, till the whole of the sensorial power, or spirit of animation, in the part becomes exhausted, a mortification ensues, as in a carbuncle, in inflammations of the bowels, in the extremities of old people, or in the limbs of those who are brought near a fire after having been much benumbed with cold. And from hence it appears, why weak people are more subject to mortification than strong ones, and why in weak persons less pain will produce mortification, namely, because the sensorial power is sooner exhausted by any excess of activity. I remember seeing a gentleman who had the preceding day travelled two stages in a chaise with what he termed a bearable pain in his bowels; which when I saw him had ceased rather suddenly, and without a passage through him; his pulse was then weak, though not very quick; but as nothing which he swallowed would continue in his stomach many minutes, I concluded that the bowel was mortified; he died on the next day. It is usual for patients sinking under the small-pox with mortified pustules, and with purple spots intermixed, to complain of no pain, but to say they are pretty well to the last moment. _Recapitulation._ IV. When the motions of any part of the system, in consequence of previous torpor, are performed with more energy than in the irritative fevers, a disagreeable sensation is produced, and new actions of some part of the system commence in consequence of this sensation conjointly with the irritation: which motions constitute inflammation. If the fever be attended with a strong pulse, as in pleurisy, or rheumatism, it is termed synocha sensitiva, or sensitive fever with strong pulse; which is usually termed inflammatory fever. If it be attended with weak pulse, it is termed typhus sensitivus, or sensitive fever with weak pulse, or typhus gravior, or putrid malignant fever. The synocha sensitiva, or sensitive fever with strong pulse, is generally attended with some topical inflammation, as in peripneumony, hepatitis, and is accompanied with much coagulable lymph, or size; which rises to the surface of the blood, when taken into a bason, as it cools; and which is believed to be the increased mucous secretion from the coats of the arteries, inspissated by a greater absorption of its aqueous and saline part, and perhaps changed by its delay in the circulation. The typhus sensitivus, or sensitive fever with weak pulse, is frequently attended with delirium, which is caused by the deficiency of the quantity of sensorial power, and with variety of cutaneous eruptions. Inflammation is caused by the pains occasioned by excess of action, and not by those pains which are occasioned by defect of action. These morbid actions, which are thus produced by two sensorial powers, viz. by irritation and sensation, secrete new living fibres, which elongate the old vessels, or form new ones, and at the same time much heat is evolved from these combinations. By the rupture of these vessels, or by a new construction of their apertures, purulent matters are secreted of various kinds; which are infectious the first time they are applied to the skin beneath the cuticle, or swallowed with the saliva into the stomach. This contagion acts not by its being absorbed into the circulation, but by the sympathies, or associated actions, between the part first stimulated by the contagious matter and the other parts of the system. Thus in the natural small-pox the contagion is swallowed with the saliva, and by its stimulus inflames the stomach; this variolous inflammation of the stomach increases every day, like the circle round the puncture of an inoculated arm, till it becomes great enough to disorder the circles of irritative and sensitive motions, and thus produces fever-fits, with sickness and vomiting. Lastly, after the cold paroxysm, or fit of torpor, of the stomach has increased for two or three successive days, an inflammation of the skin commences in points; which generally first appear upon the face, as the associated actions between the skin of the face and that of the stomach have been more frequently exerted together than those of any other parts of the external surface. Contagious matters, as those of the measles and small-pox, do not act upon the system at the same time; but the progress of that which was last received is delayed, till the action of the former infection ceases. All kinds of matter, even that from common ulcers, are probably contagious the first time they are inserted beneath the cuticle or swallowed into the stomach; that is, as they were formed by certain morbid actions of the extremities of the vessels, they have the power to excite similar morbid actions in the extremities of other vessels, to which they are applied; and these by sympathy, or associations of motion, excite similar morbid actions in distant parts of the system, without entering the circulation; and hence the blood of a patient in the small-pox will not give that disease by inoculation to others. When the new fibres or vessels become again absorbed into the circulation, the inflammation ceases; which is promoted, after sufficient evacuations, by external stimulants and bandages: but where the action of the vessels is very great, a mortification of the part is liable to ensue, owing to the exhaustion of sensorial power; which however occurs in weak people without much pain, and without very violent previous inflammation; and, like partial paralysis, may be esteemed one mode of natural death of old people, a part dying before the whole. * * * * * SECT. XXXIV. DISEASES OF VOLITION. I. 1. _Volition defined. Motions termed involuntary are caused by volition. Desires opposed to each other. Deliberation. Ass between two hay-cocks. Saliva swallowed against one's desire. Voluntary motions distinguished from those associated with sensitive motions._ 2. _Pains from excess, and from defect of motion. No pain is felt during vehement voluntary exertion; as in cold fits of ague, labour-pains, strangury, tenesmus, vomiting, restlessness in fevers, convulsion of a wounded muscle._ 3. _Of holding the breath and screaming in pain; why swine and dogs cry out in pain, and not sheep and horses. Of grinning and biting in pain; why mad animals bite others._ 4. _Epileptic convulsions explained, why the fits begin with quivering of the under jaw, biting the tongue, and setting the teeth; why the convulsive motions are alternately relaxed. The phenomenon of laughter explained. Why children cannot tickle themselves. How some have died from immoderate laughter._ 5. _Of cataleptic spasms, of the locked jaw, of painful cramps._ 6. _Syncope explained. Why no external objects are perceived in syncope._ 7. _Of palsy and apoplexy from violent exertions. Case of Mrs. Scot. From dancing, scating, swimming. Case of Mr. Nairn. Why palsies are not always immediately preceded by violent exertions. Palsy and epilepsy from diseased livers. Why the right arm more frequently paralytic than the left. How paralytic limbs regain their motions._ II. _Diseases of the sensual motions from excess or defect of voluntary exertion._ 1. _Madness._ 2. _Distinguished from delirium._ 3. _Why mankind more liable to insanity than brutes._ 4. _Suspicion. Want of shame, and of cleanliness._ 5. _They bear cold, hunger, and fatigue. Charles XII. of Sweden._ 6. _Pleasureable delirium, and insanity. Child riding on a stick. Pains of martyrdom not felt._ 7. _Dropsy._ 8. _Inflammation cured by insanity._ III. 1. _Pain relieved by reverie. Reverie is an exertion of voluntary and sensitive motions._ 2. _Case of reverie._ 3. _Lady supposed to have two souls._ 4. _Methods of relieving pain._ I. 1. Before we commence this Section on Diseased Voluntary Motions, it may be necessary to premise, that the word volition is not used in this work exactly in its common acceptation. Volition is said in Section V. to bear the same analogy to desire and aversion, which sensation does to pleasure and pain. And hence that, when desire or aversion produces any action of the muscular fibres, or of the organs of sense, they are termed volition; and the actions produced in consequence are termed voluntary actions. Whence it appears, that motions of our muscles or ideas may be produced in consequence of desire or aversion without our having the power to prevent them, and yet these motions may be termed voluntary, according to our definition of the word; though in common language they would be called involuntary. The objects of desire and aversion are generally at a distance, whereas those of pleasure and pain are immediately acting upon our organs. Hence, before desire or aversion are exerted, so as to cause any actions, there is generally time for deliberation; which consists in discovering the means to obtain the object of desire, or to avoid the object of aversion; or in examining the good or bad consequences, which may result from them. In this case it is evident, that we have a power to delay the proposed action, or to perform it; and this power of choosing, whether we shall act or not, is in common language expressed by the word volition, or will. Whereas in this work the word volition means simply the active state of the sensorial faculty in producing motion in consequence of desire or aversion: whether we have the power of restraining that action, or not; that is, whether we exert any actions in consequence of opposite desires or aversions, or not. For if the objects of desire or aversion are present, there is no necessity to investigate or compare the _means_ of obtaining them, nor do we always deliberate about their consequences; that is, no deliberation necessarily intervenes, and in consequence the power of choosing to act or not is not exerted. It is probable, that this twofold use of the word volition in all languages has confounded the metaphysicians, who have disputed about free will and necessity. Whereas from the above analysis it would appear, that during our sleep, we use no voluntary exertions at all; and in our waking hours, that they are the consequence of desire or aversion. To will is to act in consequence of desire; but to desire means to desire something, even if that something be only to become free from the pain, which causes the desire; for to desire nothing is not to desire; the word desire, therefore, includes both the action and the object or motive; for the object and motive of desire are the same thing. Hence to desire without an object, that is, without a motive, is a solecism in language. As if one should ask, if you could eat without food, or breathe without air. From this account of volition it appears, that convulsions of the muscles, as in epileptic fits, may in the common sense of that word be termed involuntary; because no deliberation is interposed between the desire or aversion and the consequent action; but in the sense of the word, as above defined, they belong to the class of voluntary motions, as delivered in Vol. II. Class III. If this use of the word be discordant to the ear of the reader, the term morbid voluntary motions, or motions in consequence of aversion, may be substituted in its stead. If a person has a desire to be cured of the ague, and has at the same time an aversion (or contrary desire) to swallowing an ounce of Peruvian bark; he balances desire against desire, or aversion against aversion; and thus he acquires the power of choosing, which is the common acceptation of the word _willing_. But in the cold fit of ague, after having discovered that the act of shuddering, or exerting the subcutaneous muscles, relieves the pain of cold; he immediately exerts this act of volition, and shudders, as soon as the pain and consequent aversion return, without any deliberation intervening; yet is this act, as well as that of swallowing an ounce of the bark, caused by volition; and that even though he endeavours in vain to prevent it by a weaker contrary volition. This recalls to our minds the story of the hungry ass between two hay-stacks, where the two desires are supposed so exactly to counteract each other, that he goes to neither of the stacks, but perishes by want. Now as two equal and opposite desires are thus supposed to balance each other, and prevent all action, it follows, that if one of these hay-stacks was suddenly removed, that the ass would irresistibly be hurried to the other, which in the common use of the word might be called an involuntary act; but which, in our acceptation of it, would be classed amongst voluntary actions, as above explained. Hence to deliberate is to compare opposing desires or aversions, and that which is the most interesting at length prevails, and produces action. Similar to this, where two pains oppose each other, the stronger or more interesting one produces action; as in pleurisy the pain from suffocation would produce expansion of the lungs, but the pain occasioned by extending the inflamed membrane, which lines the chest, opposes this expansion, and one or the other alternately prevails. When any one moves his hand quickly near another person's eyes, the eye-lids instantly close; this act in common language is termed involuntary, as we have not time to deliberate or to exert any contrary desire or aversion, but in this work it would be termed a voluntary act, because it is caused by the faculty of volition, and after a few trials the nictitation can be prevented by a contrary or opposing volition. The power of opposing volitions is best exemplified in the story of Mutius Scævola, who is said to have thrust his hand into the fire before Porcenna, and to have suffered it to be consumed for having failed him in his attempt on the life of that general. Here the aversion for the loss of same, or the unsatisfied desire to serve his country, the two prevalent enthusiasms at that time, were more powerful than the desire of withdrawing his hand, which must be occasioned by the pain of combustion; of these opposing volitions Vincit amor patriæ, laudumque immensa cupido. If any one is told not to swallow his saliva for a minute, he soon swallows it contrary to his will, in the common sense of that word; but this also is a voluntary action, as it is performed by the faculty of volition, and is thus to be understood. When the power of volition is exerted on any of our senses, they become more acute, as in our attempts to hear small noises in the night. As explained in Section XIX. 6. Hence by our attention to the fauces from our desire not to swallow our saliva; the fauces become more sensible; and the stimulus of the saliva is followed by greater sensation, and consequent desire of swallowing it. So that the desire or volition in consequence of the increased sensation of the saliva is more powerful, than the previous desire not to swallow it. See Vol. II. Deglutitio invita. In the same manner if a modest man wishes not to want to make water, when he is confined with ladies in a coach or an assembly-room; that very act of volition induces the circumstance, which he wishes to avoid, as above explained; insomuch that I once saw a partial insanity, which might be called a voluntary diabetes, which was occasioned by the fear (and consequent aversion) of not being able to make water at all. It is further necessary to observe here, to prevent any confusion of voluntary, with sensitive, or associate motions, that in all the instances of violent efforts to relieve pain, those efforts are at first voluntary exertions; but after they have been frequently repeated for the purpose of relieving certain pains, they become associated with those pains, and cease at those times to be subservient to the will; as in coughing, sneezing, and strangury. Of these motions those which contribute to remove or dislodge the offending cause, as the actions of the abdominal muscles in parturition or in vomiting, though they were originally excited by volition, are in this work termed sensitive motions; but those actions of the muscles or organs of sense, which do not contribute to remove the offending cause, as in general convulsions or in madness, are in this work termed voluntary motions, or motions in consequence of aversion, though in common language they are called involuntary ones. Those sensitive unrestrainable actions, which contribute to remove the cause of pain are uniformly and invariably exerted, as in coughing or sneezing; but those motions which are exerted in consequence of aversion without contributing to remove the painful cause, but only to prevent the sensation of it, as in epileptic, or cataleptic fits, are not uniformly and invariably exerted, but change from one set of muscles to another, as will be further explained; and may by this criterion also be distinguished from the former. At the same time those motions, which are excited by perpetual stimulus, or by association with each other, or immediately by pleasureable or painful sensation, may properly be termed involuntary motions, as those of the heart and arteries; as the faculty of volition seldom affects those, except when it exists in unnatural quantity, as in maniacal people. 2. It was observed in Section XIV. on the Production of Ideas, that those parts of the system, which are usually termed the organs of sense, are liable to be excited into pain by the excess of the stimulus of those objects, which are by nature adapted to affect them; as of too great light, sound, or pressure. But that these organs receive no pain from the defect or absence of these stimuli, as in darkness or silence. But that our other organs of perception, which have generally been called appetites, as of hunger, thirst, want of heat, want of fresh air, are liable to be affected with pain by the defect, as well as by the excess of their appropriated stimuli. This excess or defect of stimulus is however to be considered only as the remote cause of the pain, the immediate cause being the excess or defect of the natural action of the affected part, according to Sect. IV. 5. Hence all the pains of the body may be divided into those from excess of motion, and those from defect of motion; which distinction is of great importance in the knowledge and the cure of many diseases. For as the pains from excess of motion either gradually subside, or are in general succeeded by inflammation; so those from defect of motion either gradually subside, or are in general succeeded by convulsion, or madness. These pains are easily distinguishable from each other by this circumstance, that the former are attended with heat of the pained part, or of the whole body; whereas the latter exists without increase of heat in the pained part, and is generally attended with coldness of the extremities of the body; which is the true criterion of what have been called nervous pains. Thus when any acrid material, as snuff or lime, falls into the eye, pain and inflammation and heat are produced from the excess of stimulus; but violent hunger, hemicrania, or the clavus hystericus, are attended with coldness of the extremities, and defect of circulation. When we are exposed to great cold, the pain we experience from the deficiency of heat is attended with a quiescence of the motions of the vascular system; so that no inflammation is produced, but a great desire of heat, and a tremulous motion of the subcutaneous muscles, which is properly a convulsion in consequence of this pain from defect of the stimulus of heat. It was before mentioned, that as sensation consists in certain movements of the sensorium, beginning at some of the extremities of it, and propagated to the central parts of it; so volition consists of certain other movements of the sensorium, commencing in the central parts of it, and propagated to some of its extremities. This idea of these two great powers of motion in the animal machine is confirmed from observing, that they never exist in a great degree or universally at the same time; for while we strongly exert our voluntary motions, we cease to feel the pains or uneasinesses, which occasioned us to exert them. Hence during the time of fighting with fists or swords no pain is felt by the combatants, till they cease to exert themselves. Thus in the beginning of ague-fits the painful sensation of cold is diminished, while the patient exerts himself in the shivering and gnashing of his teeth. He then ceases to exert himself, and the pain of cold returns; and he is thus perpetually induced to reiterate these exertions, from which he experiences a temporary relief. The same occurs in labour-pains, the exertion of the parturient woman relieves the violence of the pains for a time, which recur again soon after she has ceased to use those exertions. The same is true in many other painful diseases, as in the strangury, tenesmus, and the efforts of vomiting; all these disagreeable sensations are diminished or removed for a time by the various exertions they occasion, and recur alternately with those exertions. The restlessness in some fevers is an almost perpetual exertion of this kind, excited to relieve some disagreeable sensations; the reciprocal opposite exertions of a wounded worm, the alternate emprosthotonos and opisthotonos of some spasmodic diseases, and the intervals of all convulsions, from whatever cause, seem to be owing to this circumstance of the laws of animation; that great or universal exertion cannot exist at the same time with great or universal sensation, though they can exist reciprocally; which is probably resolvable into the more general law, that the whole sensorial power being expended in one mode of exertion, there is none to spare for any other. Whence syncope, or temporary apoplexy, succeeds to epileptic convulsions. 3. Hence when any violent pain afflicts us, of which we can neither avoid nor remove the cause, we soon learn to endeavour to alleviate it, by exerting some violent voluntary effort, as mentioned above; and are naturally induced to use those muscles for this purpose, which have been in the early periods of our lives most frequently or most powerfully exerted. Now the first muscles, which infants use most frequently, are those of respiration; and on this account we gain a habit of holding our breath, at the same time that we use great efforts to exclude it, for this purpose of alleviating unavoidable pain; or we press out our breath through a small aperture of the larynx, and scream violently, when the pain is greater than is relievable by the former mode of exertion. Thus children scream to relieve any pain either of body or mind, as from anger, or fear of being beaten. Hence it is curious to observe, that those animals, who have more frequently exerted their muscles of respiration violently, as in talking, barking, or grunting, as children, dogs, hogs, scream much more, when they are in pain, than those other animals, who use little or no language in their common modes of life; as horses, sheep, and cows. The next most frequent or most powerful efforts, which infants are first tempted to produce, are those with the muscles in biting hard substances; indeed the exertion of these muscles is very powerful in common mastication, as appears from the pain we receive, if a bit of bone is unexpectedly found amongst our softer food; and further appears from their acting to so great mechanical disadvantage, particularly when we bite with the incisores, or canine teeth; which are first formed, and thence are first used to violent exertion. Hence when a person is in great pain, the cause of which he cannot remove, he sets his teeth firmly together, or bites some substance between them with great vehemence, as another mode of violent exertion to produce a temporary relief. Thus we have a proverb where no help can be had in pain, "to grin and abide;" and the tortures of hell are said to be attended with "gnashing of teeth." Hence in violent spasmodic pains I have seen people bite not only their tongues, but their arms or fingers, or those of the attendants, or any object which was near them; and also strike, pinch, or tear, others or themselves, particularly the part of their own body, which is painful at the time. Soldiers, who die of painful wounds in battle, are said in Homer to bite the ground. Thus also in the bellon, or colica saturnina, the patients are said to bite their own flesh, and dogs in this disease to bite up the ground they lie upon. It is probable that the great endeavours to bite in mad dogs, and the violence of other mad animals, is owing to the same cause. 4. If the efforts of our voluntary motions are exerted with still greater energy for the relief of some disagreeable sensation, convulsions are produced; as the various kinds of epilepsy, and in some hysteric paroxysms. In all these diseases a pain, or disagreeable sensation is produced, frequently by worms, or acidity in the bowels, or by a diseased nerve in the side, or head, or by the pain of a diseased liver. In some constitutions a more intolerable degree of pain is produced in some part at a distance from the cause by sensitive association, as before explained; these pains in such constitutions arise to so great a degree, that I verily believe no artificial tortures could equal some, which I have witnessed; and am confident life would not have long been preserved, unless they had been soon diminished or removed by the universal convulsion of the voluntary motions, or by temporary madness. In some of the unfortunate patients I have observed, the pain has risen to an inexpressible degree, as above described, before the convulsions have supervened; and which were preceded by screaming, and grinning; in others, as in the common epilepsy, the convulsion has immediately succeeded the commencement of the disagreeable sensations; and as a stupor frequently succeeds the convulsions, they only seemed to remember that a pain at the stomach preceded the fit, or some other uneasy feel; or more frequently retained no memory at all of the immediate cause of the paroxysm. But even in this kind of epilepsy, where the patient does not recollect any preceding pain, the paroxysms generally are preceded by a quivering motion of the under jaw, with a biting of the tongue; the teeth afterwards become pressed together with vehemence, and the eyes are then convulsed, before the commencement of the universal convulsion; which are all efforts to relieve pain. The reason why these convulsive motions are alternately exerted and remitted was mentioned above, and in Sect. XII. 1. 3. when the exertions are such as give a temporary relief to the pain, which excites them, they cease for a time, till the pain is again perceived; and then new exertions are produced for its relief. We see daily examples of this in the loud reiterated laughter of some people; the pleasureable sensation, which excites this laughter, arises for a time so high as to change its name and become painful: the convulsive motions of the respiratory muscles relieve the pain for a time; we are, however, unwilling to lose the pleasure, and presently put a stop to this exertion, and immediately the pleasure recurs, and again as instantly rises into pain. All of us have felt the pain of immoderate laughter; children have been tickled into convulsions of the whole body; and others have died in the act of laughing; probably from a paralysis succeeding the long continued actions of the muscles of respiration. Hence we learn the reason, why children, who are so easily excited to laugh by the tickling of other people's fingers, cannot tickle themselves into laughter. The exertion of their hands in the endeavour to tickle themselves prevents the necessity of any exertion of the respiratory muscles to relieve the excess of pleasurable affection. See Sect. XVII. 3. 5. Chrysippus is recorded to have died laughing, when an ass was invited to sup with him. The same is related of one of the popes, who, when he was ill, saw a tame monkey at his bedside put on the holy thiara. Hall. Phys. T. III. p. 306. There are instances of epilepsy being produced by laughing recorded by Van Swieten, T. III. 402 and 308. And it is well known, that many people have died instantaneously from the painful excess of joy, which probably might have been prevented by the exertions of laughter. Every combination of ideas, which we attend to, occasions pain or pleasure; those which occasion pleasure, furnish either social or selfish pleasure, either malicious or friendly, or lascivious, or sublime pleasure; that is, they give us pleasure mixed with other emotions, or they give us unmixed pleasure, without occasioning any other emotions or exertions at the same time. This unmixed pleasure, if it be great, becomes painful, like all other animal motions from stimuli of every kind; and if no other exertions are occasioned at the same time, we use the exertion of laughter to relieve this pain. Hence laughter is occasioned by such wit as excites simple pleasure without any other emotion, such as pity, love, reverence. For sublime ideas are mixed with admiration, beautiful ones with love, new ones with surprise; and these exertions of our ideas prevent the action of laughter from being necessary to relieve the painful pleasure above described. Whence laughable wit consists of frivolous ideas, without connections of any consequence, such as puns on words, or on phrases, incongruous junctions of ideas; on which account laughter is so frequent in children. Unmixed pleasure less than that, which causes laughter, causes sleep, as in singing children to sleep, or in slight intoxication from wine or food. See Sect. XVIII. 12. 5. If the pains, or disagreeable sensations, above described do not obtain a temporary relief from these convulsive exertions of the muscles, those convulsive exertions continue without remission, and one kind of catalepsy is produced. Thus when a nerve or tendon produces great pain by its being inflamed or wounded, the patient sets his teeth firmly together, and grins violently, to diminish the pain; and if the pain is not relieved by this exertion, no relaxation of the maxillary muscles takes place, as in the convulsions above described, but the jaws remain firmly fixed together. This locked jaw is the most frequent instance of cataleptic spasm, because we are more inclined to exert the muscles subservient to mastication from their early obedience to violent efforts of volition. But in the case related in Sect. XIX. on Reverie, the cataleptic lady had pain in her upper teeth; and pressing one of her hands vehemently against her cheek-bone to diminish this pain, it remained in that attitude for about half an hour twice a day, till the painful paroxysm was over. I have this very day seen a young lady in this disease, (with which she has frequently been afflicted,) she began to-day with violent pain shooting from one side of the forehead to the occiput, and after various struggles lay on the bed with her fingers and wrists bent and stiff for about two hours; in other respects she seemed in a syncope with a natural pulse. She then had intervals of pain and of spasm, and took three grains of opium every hour till she had taken nine grains, before the pains and spasm ceased. There is, however, another species of fixed spasm, which differs from the former, as the pain exists in the contracted muscle, and would seem rather to be the consequence than the cause of the contraction, as in the cramp in the calf of the leg, and in many other parts of the body. In these spasms it should seem, that the muscle itself is first thrown into contraction by some disagreeable sensation, as of cold; and that then the violent pain is produced by the great contraction of the muscular fibres extending its own tendons, which are said to be sensible to extension only; and is further explained in Sect. XVIII. 15. 6. Many instances have been given in this work, where after violent motions excited by irritation, the organ has become quiescent to less, and even to the great irritation, which induced it into violent motion; as after looking long at the sun or any bright colour, they cease to be seen; and after removing from bright day-light into a gloomy room, the eye cannot at first perceive the objects, which stimulate it less. Similar to this is the syncope, which succeeds after the violent exertions of our voluntary motions, as after epileptic fits, for the power of volition acts in this case as the stimulus in the other. This syncope is a temporary palsy, or apoplexy, which ceases after a time, the muscles recovering their power of being excited into action by the efforts of volition; as the eye in the circumstance above mentioned recovers in a little time its power of seeing objects in a gloomy room; which were invisible immediately after coming out of a stronger light. This is owing to an accumulation of sensorial power during the inaction of those fibres, which were before accustomed to perpetual exertions, as explained in Sect. XII. 7. 1. A slighter degree of this disease is experienced by every one after great fatigue, when the muscles gain such inability to further action, that we are obliged to rest them for a while, or to summon a greater power of volition to continue their motions. In all the syncopes, which I have seen induced after convulsive fits, the pulse has continued natural, though the organs of sense, as well as the locomotive muscles, have ceased to perform their functions; for it is necessary for the perception of objects, that the external organs of sense should be properly excited by the voluntary power, as the eye-lids must be open, and perhaps the muscles of the eye put into action to distend, and thence give greater pellucidity to the cornea, which in syncope, as in death, appears flat and less transparent. The tympanum of the ear also seems to require a voluntary exertion of its muscles, to gain its due tension, and it is probable the other external organs of sense require a similar voluntary exertion to adapt them to the distinct perception of objects. Hence in syncope as in sleep, as the power of volition is suspended, no external objects are perceived. See Sect. XVIII. 5. During the time which the patient lies in a fainting fit, the spirit of animation becomes accumulated; and hence the muscles in a while become irritable by their usual stimulation, and the fainting fit ceases. See Sect. XII. 7. 1. 7. If the exertion of the voluntary motions has been still more energetic, the quiescence, which succeeds, is so complete, that they cannot again be excited into action by the efforts of the will. In this manner the palsy, and apoplexy (which is an universal palsy) are frequently produced after convulsions, or other violent exertions; of this I shall add a few instances. Platernus mentions some, who have died apoplectic from violent exertions in dancing; and Dr. Mead, in his Essay on Poisons, records a patient in the hydrophobia, who at one effort broke the cords which bound him, and at the same instant expired. And it is probable, that those, who have expired from immoderate laughter, have died from this paralysis consequent to violent exertion. Mrs. Scott of Stafford was walking in her garden in perfect health with her neighbour Mrs. ----; the latter accidentally fell into a muddy rivulet, and tried in vain to disengage herself by the assistance of Mrs. Scott's hand. Mrs. Scott exerted her utmost power for many minutes, first to assist her friend, and next to prevent herself from being pulled into the morass, as her distressed companion would not disengage her hand. After other assistance was procured by their united screams, Mrs. Scott walked to a chair about twenty yards from the brook, and was seized with an apoplectic stroke: which continued many days, and terminated in a total loss of her right arm, and her speech; neither of which she ever after perfectly recovered. It is said, that many people in Holland have died after skating too long or too violently on their frozen canals; it is probable the death of these, and of others, who have died suddenly in swimming, has been owing to this great quiescence or paralysis; which has succeeded very violent exertions, added to the concomitant cold, which has had greater effect after the sufferers had been heated and exhausted by previous exercise. I remember a young man of the name of Nairne at Cambridge, who walking on the edge of a barge fell into the river. His cousin and fellow-student of the same name, knowing the other could not swim, plunged into the water after him, caught him by his clothes, and approaching the bank by a vehement exertion propelled him safe to the land, but that instant, seized, as was supposed, by the cramp, or paralysis, sunk to rise no more. The reason why the cramp of the muscles, which compose the calf of the leg, is so liable to affect swimmers, is, because these muscles have very weak antagonists, and are in walking generally elongated again after their contraction by the weight of the body on the ball of the toe, which is very much greater than the resistance of the water in swimming. See Section XVIII. 15. It does not follow that every apoplectic or paralytic attack is immediately preceded by vehement exertion; the quiescence, which succeeds exertion, and which is not so great as to be termed paralysis, frequently recurs afterwards at certain periods; and by other causes of quiescence, occurring with those periods, as was explained in treating of the paroxysms of intermitting fevers; the quiescence at length, becomes so great as to be incapable of again being removed by the efforts of volition, and complete paralysis is formed. See Section XXXII. 3. 2. Many of the paralytic patients, whom I have seen, have evidently had diseased livers from the too frequent potation of spirituous liquors; some of them have had the gutta rosea on their faces and breasts; which has in some degree receded either spontaneously, or by the use of external remedies, and the paralytic stroke has succeeded; and as in several persons, who have drank much vinous spirits, I have observed epileptic fits to commence at about forty or fifty years of age, without any hereditary taint, from the stimulus, as I believed, of a diseased liver; I was induced to ascribe many paralytic cases to the same source; which were not evidently the effect of age, or of unacquired debility. And the account given before of dropsies, which very frequently are owing to a paralysis of the absorbent system, and are generally attendant on free drinkers of spirituous liquors, confirmed me in this opinion. The disagreeable irritation of a diseased liver produces exertions and consequent quiescence; these by the accidental concurrence of other causes of quiescence, as cold, solar or lunar periods, inanition, the want of their usual portion of spirit of wine, at length produces paralysis. This is further confirmed by observing, that the muscles, we most frequently, or most powerfully exert, are most liable to palsy; as those of the voice and of articulation, and of those paralytics which I have seen, a much greater proportion have lost the use of their right arm; which is so much more generally exerted than the left. I cannot dismiss this subject without observing, that after a paralytic stroke, if the vital powers are not much injured, that the patient has all the movements of the affected limb to learn over again, just as in early infancy; the limb is first moved by the irritation of its muscles, as in stretching, (of which a case was related in Section VII. 1. 3.) or by the electric concussion; afterwards it becomes obedient to sensation, as in violent danger or fear; and lastly, the muscles become again associated with volition, and gradually acquire their usual habits of acting together. Another phænomenon in palsies is, that when the limbs of one side are disabled, those of the other are in perpetual motion. This can only be explained from conceiving that the power of motion, whatever it is, or wherever it resides, and which is capable of being exhausted by fatigue, and accumulated in rest, is now less expended, whilst one half of the body is capable of receiving its usual proportion of it, and is hence derived with greater ease or in greater abundance into the limbs, which remain unaffected. II. 1. The excess or defect of voluntary exertion produces similar effects upon the sensual motions, or ideas of the mind, as those already mentioned upon the muscular fibres. Thus when any violent pain, arising from the defect of some peculiar stimulus, exists either in the muscular or sensual systems of fibres, and which cannot be removed by acquiring the defective stimulus; as in some constitutions convulsions of the muscles are produced to procure a temporary relief, so in other constitutions vehement voluntary exertions of the ideas of the mind are produced for the same purpose; for during this exertion, like that of the muscles, the pain either vanishes or is diminished: this violent exertion constitutes madness; and in many cases I have seen the madness take place, and the convulsions cease, and reciprocally the madness cease, and the convulsions supervene. See Section III. 5. 8. 2. Madness is distinguishable from delirium, as in the latter the patient knows not the place where he resides, nor the persons of his friends or attendants, nor is conscious of any external objects, except when spoken to with a louder voice, or stimulated with unusual force, and even then he soon relapses into a state of inattention to every thing about him. Whilst in the former he is perfectly sensible to every thing external, but has the voluntary powers of his mind intensely exerted on some particular object of his desire or aversion, he harbours in his thoughts a suspicion of all mankind, lest they should counteract his designs; and while he keeps his intentions, and the motives of his actions profoundly secret; he is perpetually studying the means of acquiring the object of his wish, or of preventing or revenging the injuries he suspects. 3. A late French philosopher, Mr. Helvetius, has deduced almost all our actions from this principle of their relieving us from the ennui or tædium vitæ; and true it is, that our desires or aversions are the motives of all our voluntary actions; and human nature seems to excel other animals in the more facil use of this voluntary power, and on that account is more liable to insanity than other animals. But in mania this violent exertion of volition is expended on mistaken objects, and would not be relieved, though we were to gain or escape the objects, that excite it. Thus I have seen two instances of madmen, who conceived that they had the itch, and several have believed they had the venereal infection, without in reality having a symptom of either of them. They have been perpetually thinking upon this subject, and some of them were in vain salivated with design of convincing them to the contrary. 4. In the minds of mad people those volitions alone exist, which are unmixed with sensation; immoderate suspicion is generally the first symptom, and want of shame, and want of delicacy about cleanliness. Suspicion is a voluntary exertion of the mind arising from the pain of fear, which it is exerted to relieve: shame is the name of a peculiar disagreeable sensation, see Fable of the Bees, and delicacy about cleanliness arises from another disagreeable sensation. And therefore are not found in the minds of maniacs, which are employed solely in voluntary exertions. Hence the most modest women in this disease walk naked amongst men without any kind of concern, use obscene discourse, and have no delicacy about their natural evacuations. 5. Nor are maniacal people more attentive to their natural appetites, or to the irritations which surround them, except as far as may respect their suspicions or designs; for the violent and perpetual exertions of their voluntary powers of mind prevents their perception of almost every other object, either of irritation or of sensation. Hence it is that they bear cold, hunger, and fatigue, with much greater pertinacity than in their sober hours, and are less injured by them in respect to their general health. Thus it is asserted by historians, that Charles the Twelfth of Sweden slept on the snow, wrapped only in his cloak, at the siege of Frederickstad, and bore extremes of cold and hunger, and fatigue, under which numbers of his soldiers perished; because the king was insane with ambition, but the soldier had no such powerful stimulus to preserve his system from debility and death. 6. Besides the insanities arising from exertions in consequence of pain, there is also a pleasurable insanity, as well as a pleasurable delirium; as the insanity of personal vanity, and that of religious fanaticism. When agreeable ideas excite into motion the sensorial power of sensation, and this again causes other trains of agreeable ideas, a constant stream of pleasurable ideas succeeds, and produces pleasurable delirium. So when the sensorial power of volition excites agreeable ideas, and the pleasure thus produced excites more volition in its turn, a constant flow of agreeable voluntary ideas succeeds; which when thus exerted in the extreme constitutes insanity. Thus when our muscular actions are excited by our sensations of pleasure, it is termed play; when they are excited by our volition, it is termed work; and the former of these is attended with less fatigue, because the muscular actions in play produce in their turn more pleasurable sensation; which again has the property of producing more muscular action. An agreeable instance of this I saw this morning. A little boy, who was tired with walking, begged of his papa to carry him. "Here," says the reverend doctor, "ride upon my gold-headed cane;" and the pleased child, putting it between his legs, gallopped away with delight, and complained no more of his fatigue. Here the aid of another sensorial power, that of pleasurable sensation, superadded vigour to the exertion of exhausted volition. Which could otherwise only have been excited by additional pain, as by the lash of slavery. On this account where the whole sensorial power has been exerted on the contemplation of the promised joys of heaven, the saints of all persecuted religions have borne the tortures of martyrdom with otherwise unaccountable firmness. 7. There are some diseases, which obtain at least a temporary relief from the exertions of insanity; many instances of dropsies being thus for a time cured are recorded. An elderly woman labouring with ascites I twice saw relieved for some weeks by insanity, the dropsy ceased for several weeks, and recurred again alternating with the insanity. A man afflicted with difficult respiration on lying down, with very irregular pulse, and oedematous legs, whom I saw this day, has for above a week been much relieved in respect to all those symptoms by the accession of insanity, which is shewn by inordinate suspicion, and great anger. In cases of common temporary anger the increased action of the arterial system is seen by the red skin, and increased pulse, with the immediate increase of muscular activity. A friend of mine, when he was painfully fatigued by riding on horseback, was accustomed to call up ideas into his mind, which used to excite his anger or indignation, and thus for a time at least relieved the pain of fatigue. By this temporary insanity, the effect of the voluntary power upon the whole of his system was increased; as in the cases of dropsy above mentioned, it would appear, that the increased action of the voluntary faculty of the sensorium affected the absorbent system, as well as the secerning one. 8. In respect to relieving inflammatory pains, and removing fever, I have seen many instances, as mentioned in Sect. XII. 2. 4. One lady, whom I attended, had twice at some years interval a locked jaw, which relieved a pain on her sternum with peripneumony. Two other ladies I saw, who towards the end of violent peripneumony, in which they frequently lost blood, were at length cured by insanity supervening. In the former the increased voluntary exertion of the muscles of the jaw, in the latter that of the organs of sense, removed the disease; that is, the disagreeable sensation, which had produced the inflammation, now excited the voluntary power, and these new voluntary exertions employed or expended the superabundant sensorial power, which had previously been exerted on the arterial system, and caused inflammation. Another case, which I think worth relating, was of a young man about twenty; he had laboured under an irritative fever with debility for three or four weeks, with very quick and very feeble pulse, and other usual symptoms of that species of typhus, but at this time complained much and frequently of pain of his legs and feet. When those who attended him were nearly in despair of his recovery, I observed with pleasure an insanity of mind supervene: which was totally different from delirium, as he knew his friends, calling them by their names, and the room in which he lay, but became violently suspicious of his attendants, and calumniated with vehement oaths his tender mother, who sat weeping by his bed. On this his pulse became slower and firmer, but the quickness did not for some time intirely cease, and he gradually recovered. In this case the introduction of an increased quantity of the power of volition gave vigour to those movements of the system, which are generally only actuated by the power of irritation, and of association. Another case I recollect of a young man, about twenty-five, who had the scarlet-fever, with very quick pulse, and an universal eruption on his skin, and was not without reason esteemed to be in great danger of his life. After a few days an insanity supervened, which his friends mistook for delirium, and he gradually recovered, and the cuticle peeled off. From these and a few other cases I have always esteemed insanity to be a favourable sign in fevers, and have cautiously distinguished it from delirium. III. Another mode of mental exertion to relieve pain, is by producing a train of ideas not only by the efforts of volition, as in insanity; but by those of sensation likewise, as in delirium and sleep. This mental effort is termed reverie, or somnambulation, and is described more at large in Sect. XIX. on that subject. But I shall here relate another case of that wonderful disease, which fell yesterday under my eye, and to which I have seen many analogous alienations of mind, though not exactly similar in all circumstances. But as all of them either began or terminated with pain or convulsion, there can be no doubt but that they are of epileptic origin, and constitute another mode of mental exertion to relieve some painful sensation. 1. Master A. about nine years old, had been seized at seven every morning for ten days with uncommon fits, and had had slight returns in the afternoon. They were supposed to originate from worms, and had been in vain attempted to be removed by vermifuge purges. As his fit was expected at seven yesterday morning, I saw him before that hour; he was asleep, seemed free from pain, and his pulse natural. About seven he began to complain of pain about his navel, or more to the left side, and in a few minutes had exertions of his arms and legs like swimming. He then for half an hour hunted a pack of hounds; as appeared by his hallooing, and calling the dogs by their names, and discoursing with the attendants of the chase, describing exactly a day of hunting, which (I was informed) he had witnessed a year before, going through all the most minute circumstances of it; calling to people, who were then present, and lamenting the absence of others, who were then also absent. After this scene he imitated, as he lay in bed, some of the plays of boys, as swimming and jumping. He then sung an English and then an Italian song; part of which with his eyes open, and part with them closed, but could not be awakened or excited by any violence, which it was proper to use. After about an hour he came suddenly to himself with apparent surprise, and seemed quite ignorant of any part of what had passed, and after being apparently well for half an hour, he suddenly fell into a great stupor, with slower pulse than natural, and a slow moaning respiration, in which he continued about another half hour, and then recovered. The sequel of this disease was favourable; he was directed one grain of opium at six every morning, and then to rise out of bed; at half past six he was directed fifteen drops of laudanum in a glass of wine and water. The first day the paroxysm became shorter, and less violent. The dose of opium was increased to one-half more, and in three or four days the fits left him. The bark and filings of iron were also exhibited twice a day; and I believe the complaint returned no more. 2. In this paroxysm it must be observed, that he began with pain, and ended with stupor, in both circumstances resembling a fit of epilepsy. And that therefore the exertions both of mind and body, both the voluntary ones, and those immediately excited by pleasurable sensation, were exertions to relieve pain. The hunting scene appeared to be rather an act of memory than of imagination, and was therefore rather a voluntary exertion, though attended with the pleasurable eagerness, which was the consequence of those ideas recalled by recollection, and not the cause of them. These ideas thus voluntarily recollected were succeeded by sensations of pleasure, though his senses were unaffected by the stimuli of visible or audible objects; or so weakly excited by them as not to produce sensation or attention. And the pleasure thus excited by volition produced other ideas and other motions in consequence of the sensorial power of sensation. Whence the mixed catenations of voluntary and sensitive ideas and muscular motions in reverie; which, like every other kind of vehement exertion, contribute to relieve pain, by expending a large quantity of sensorial power. Those fits generally commence during sleep, from whence I suppose they have been thought to have some connection with sleep, and have thence been termed Somnambulism; but their commencement during sleep is owing to our increased excitability by internal sensations at that time, as explained in Sect. XVIII. 14. and 15., and not to any similitude between reverie and sleep. 3. I was once concerned for a very elegant and ingenious young lady, who had a reverie on alternate days, which continued nearly the whole day; and as in her days of disease she took up the same kind of ideas, which she had conversed about on the alternate day before, and could recollect nothing of them on her well-day; she appeared to her friends to possess two minds. This case also was of epileptic kind, and was cured, with some relapses, by opium administered before the commencement of the paroxysm. 4. Whence it appears, that the methods of relieving inflammatory pains, is by removing all stimulus, as by venesection, cool air, mucilaginous diet, aqueous potation, silence, darkness. The methods of relieving pains from defect of stimulus is by supplying the peculiar stimulus required, as of food, or warmth. And the general method of relieving pain is by exciting into action some great part of the system for the purpose of expending a part of the sensorial power. This is done either by exertion of the voluntary ideas and muscles, as in insanity and convulsion; or by exerting both voluntary and sensitive motions, as in reverie; or by exciting the irritative motions by wine or opium internally, and by the warm bath or blisters externally; or lastly, by exciting the sensitive ideas by good news, affecting stories, or agreeable passions. * * * * * SECT. XXXV. DISEASES OF ASSOCIATION. I. 1. _Sympathy or consent of parts. Primary and secondary parts of an associated train of motions reciprocally affect each other. Parts of irritative trains of motion affect each other in four ways. Sympathies of the skin and stomach. Flushing of the face after a meal. Eruption of the small-pox on the face. Chilness after a meal._ 2. _Vertigo from intoxication._ 3. _Absorption from the lungs and pericardium by emetics. In vomiting the actions of the stomach are decreased, not increased. Digestion strengthened after an emetic. Vomiting from deficiency of sensorial power._ 4. _Dyspnoea from cold bathing. Slow pulse from digitalis. Death from gout in the stomach._ II. 1. _Primary and secondary parts of sensitive associations affect each other. Pain from gall-stone, from urinary stone, Hemicrania. Painful epilepsy._ 2. _Gout and red face from inflamed liver. Shingles from inflamed kidney._ 3. _Coryza from cold applied to the feet. Pleurisy. Hepatitis._ 4. _Pain of shoulders from inflamed liver._ III. _Diseases from the associations of ideas._ I. 1. Many synchronous and successive motions of our muscular fibres, and of our organs of sense, or ideas, become associated so as to form indissoluble tribes or trains of action, as shewn in Section X. on Associate Motions. Some constitutions more easily establish these associations, whether by voluntary, sensitive, or irritative repetitions, and some more easily lose them again, as shewn in Section XXXI. on Temperaments. When the beginning of such a train of actions becomes by any means disordered, the succeeding part is liable to become disturbed in consequence, and this is commonly termed sympathy or consent of parts by the writers of medicine. For the more clear understanding of these sympathies we must consider a tribe or train of actions as divided into two parts, and call one of them the primary or original motions, and the other the secondary or sympathetic ones. The primary and secondary parts of a train of irritative actions may reciprocally affect each other in four different manners. 1. They may both be exerted with greater energy than natural. 2. The former may act with greater, and the latter with less energy. 3. The former may act with less, and the latter with greater energy. 4. They may both act with less energy than natural. I shall now give an example of each kind of these modes of action, and endeavour to shew, that though the primary and secondary parts of these trains or tribes of motion are connected by irritative association, or their previous habits of acting together, as described in Sect. XX. on Vertigo. Yet that their acting with similar or dissimilar degrees of energy, depends on the greater or less quantity of sensorial power, which the primary part of the train expends in its exertions. The actions of the stomach constitute so important a part of the associations of both irritative and sensitive motions, that it is said to sympathize with almost every part of the body; the first example, which I shall adduce to shew that both the primary and secondary parts of a train of irritative associations of motion act with increased energy, is taken from the consent of the skin with this organ. When the action of the fibres of the stomach is increased, as by the stimulus of a full meal, the exertions of the cutaneous arteries of the face become increased by their irritative associations with those of the stomach, and a glow or flushing of the face succeeds. For the small vessels of the skin of the face having been more accustomed to the varieties of action, from their frequent exposure to various degrees of cold and heat become more easily excited into increased action, than those of the covered parts of our bodies, and thus act with more energy from their irritative or sensitive associations with the stomach. On this account in small-pox the eruption in consequence of the previous affection of the stomach breaks out a day sooner on the face than on the hands, and two days sooner than on the trunk, and recedes in similar times after maturation. But secondly, in weaker constitutions, that is, in those who possess less sensorial power, so much of it is expended in the increased actions of the fibres of the stomach excited by the stimulus of a meal, that a sense of chilness succeeds instead of the universal glow above mentioned; and thus the secondary part of the associated train of motions is diminished in energy, in consequence of the increased activity of the primary part of it. 2. Another instance of a similar kind, where the secondary part of the train acts with less energy in consequence of the greater exertions of the primary part, is the vertigo attending intoxication; in this circumstance so much sensorial power is expended on the stomach, and on its nearest or more strongly associated motions, as those of the subcutaneous vessels, and probably of the membranes of some internal viscera, that the irritative motions of the retina become imperfectly exerted from deficiency of sensorial power, as explained in Sect. XX. and XXI. 3. on Vertigo and on Drunkenness, and hence the staggering inebriate cannot completely balance himself by such indistinct vision. 3. An instance of the third circumstance, where the primary part of a train of irritative motions acts with less, and the secondary part with greater energy, may be observed by making the following experiment. If a person lies with his arms and shoulders out of bed, till they become cold, a temporary coryza or catarrh is produced; so that the passage of the nostrils becomes totally obstructed; at least this happens to many people; and then on covering the arms and shoulders, till they become warm, the passage of the nostrils ceases again to be obstructed, and a quantity of mucus is discharged from them. In this case the quiescence of the vessels of the skin of the arms and shoulders, occasioned by exposure to cold air, produces by irritative association an increased action of the vessels of the membrane of the nostrils; and the accumulation of sensorial power during the torpor of the arms and shoulders is thus expended in producing a temporary coryza or catarrh. Another instance may be adduced from the sympathy or consent of the motions of the stomach with other more distant links of the very extensive tribes or trains of irritative motions associated with them, described in Sect. XX. on Vertigo. When the actions of the fibres of the stomach are diminished or inverted, the actions of the absorbent vessels, which take up the mucus from the lungs, pericardium, and other cells of the body, become increased, and absorb the fluids accumulated in them with greater avidity, as appears from the exhibition of foxglove, antimony, or other emetics in cases of anasarca, attended with unequal pulse and difficult respiration. That the act of nausea and vomiting is a decreased exertion of the fibres of the stomach may be thus deduced; when an emetic medicine is administered, it produces the pain of sickness, as a disagreeable taste in the mouth produces the pain of nausea; these pains, like that of hunger, or of cold, or like those, which are usually termed nervous, as the head-ach or hemicrania, do not excite the organ into greater action; but in this case I imagine the pains of sickness or of nausea counteract or destroy the pleasurable sensation, which seems necessary to digestion, as shewn in Sect. XXXIII. 1. 1. The peristaltic motions of the fibres of the stomach become enfeebled by the want of this stimulus of pleasurable sensation, and in consequence stop for a time, and then become inverted; for they cannot become inverted without being previously stopped. Now that this inversion of the trains of motion of the fibres of the stomach is owing to the deficiency of pleasurable sensation is evinced from this circumstance, that a nauseous idea excited by words will produce vomiting as effectually us a nauseous drug. Hence it appears, that the act of nausea or vomiting expends less sensorial power than the usual peristaltic motions of the stomach in the digestion of our aliment; and that hence there is a greater quantity of sensorial power becomes accumulated in the fibres of the stomach, and more of it in consequence to spare for the action of those parts of the system, which are thus associated with the stomach, as of the whole absorbent series of vessels, and which are at the same time excited by their usual stimuli. From this we can understand, how after the operation of an emetic the stomach becomes more irritable and sensible to the stimulus, and the pleasure of food; since as the sensorial power becomes accumulated during the nausea and vomiting, the digestive power is afterwards exerted more forceably for a time. It should, however, be here remarked, that though vomiting is in general produced by the defect of this stimulus of pleasurable sensation, as when a nauseous drug is administered; yet in long continued vomiting, as in sea-sickness, or from habitual dram-drinking, it arises from deficiency of sensorial power, which in the former case is exhausted by the increased exertion of the irritative ideas of vision, and in the latter by the frequent application of an unnatural stimulus. 4. An example of the fourth circumstance above mentioned, where both the primary and secondary parts of a train of motions proceed with energy less than natural, may be observed in the dyspnoea, which occurs in going into a very cold bath, and which has been described and explained in Sect. XXXII. 3. 2. And by the increased debility of the pulsations of the heart and arteries during the operation of an emetic. Secondly, from the slowness and intermission of the pulsations of the heart from the incessant efforts to vomit occasioned by an overdose of digitalis. And thirdly, from the total stoppage of the motions of the heart, or death, in consequence of the torpor of the stomach, when affected with the commencement or cold paroxysm of the gout. See Sect. XXV. 17. II. 1. The primary and secondary parts of the trains of sensitive association reciprocally affect each other in different manners. 1. The increased sensation of the primary part may cease, when that of the secondary part commences. 2. The increased action of the primary part may cease, when that of the secondary part commences. 3. The primary part may have increased sensation, and the secondary part increased action. 4. The primary part may have increased action, and the secondary part increased sensation. Examples of the first mode, where the increased sensation of the primary part of a train of sensitive association ceases, when that of the secondary part commences, are not unfrequent; as this is the general origin of those pains, which continue some time without being attended with inflammation, such as the pain at the pit of the stomach from a stone at the neck of the gall-bladder, and the pain of strangury in the glans penis from a stone at the neck of the urinary bladder. In both these cases the part, which is affected secondarily, is believed to be much more sensible than the part primarily affected, as described in the catalogue of diseases, Class II. 1. 1. 11. and IV. 2. 2. 2. and IV. 2. 2. 4. The hemicrania, or nervous headach, as it is called, when it originates from a decaying tooth, is another disease of this kind; as the pain of the carious tooth always ceases, when the pain over one eye and temple commences. And it is probable, that the violent pains, which induce convulsions in painful epilepsies, are produced in the same manner, from a more sensible part sympathizing with a diseased one of less sensibility. See Catalogue of Diseases, Class IV. 2. 2. 8. and III. 1. 1. 6. The last tooth, or dens sapientiæ, of the upper jaw most frequently decays first, and is liable to produce pain over the eye and temple of that side. The last tooth of the under-jaw is also liable to produce a similar hemicrania, when it begins to decay. When a tooth in the upper-jaw is the cause of the headach, a slighter pain is sometimes perceived on the cheek-bone. And when a tooth in the lower-jaw is the cause of headach, a pain sometimes affects the tendons of the muscles of the neck, which are attached near the jaws. But the clavus hystericus, or pain about the middle of the parietal bone on one side of the head, I have seen produced by the second of the molares, or grinders, of the under-jaw; of which I shall relate the following case. See Class IV. 2. 2. 8. Mrs. ----, about 30 years of age, was seized with great pain about the middle of the right parietal bone, which had continued a whole day before I saw her, and was so violent as to threaten to occasion convulsions. Not being able to detect a decaying tooth, or a tender one, by examination with my eye, or by striking them with a tea-spoon, and fearing bad consequences from her tendency to convulsion, I advised her to extract the last tooth of the under-jaw on the affected side; which was done without any good effect. She was then directed to lose blood, and to take a brisk cathartic; and after that had operated, about 60 drops of laudanum were given her, with large doses of bark; by which the pain was removed. In about a fortnight she took a cathartic medicine by ill advice, and the pain returned with greater violence in the same place; and, before I could arrive, as she lived 30 miles from me, she suffered a paralytic stroke; which affected her limbs and her face on one side, and relieved the pain of her head. About a year afterwards I was again called to her on account of a pain as violent as before exactly on the same part of the other parietal bone. On examining her mouth I found the second molaris of the under-jaw on the side before affected was now decayed, and concluded, that this tooth had occasioned the stroke of the palsy by the pain and consequent exertion it had caused. On this account I earnestly entreated her to allow the sound molaris of the same jaw opposite to the decayed one to be extracted; which was forthwith done, and the pain of her head immediately ceased, to the astonishment of her attendants. In the cases above related of the pain existing in a part distant from the seat of the disease, the pain is owing to defect of the usual motions of the painful part. This appears from the coldness, paleness, and emptiness of the affected vessels, or of the extremities of the body in general, and from there being no tendency to inflammation. The increased action of the primary part of these associated motions, as of the hepatic termination of the bile-duct; from the stimulus of a gall-stone, or of the interior termination of the urethra from the stimulus of a stone in the bladder, or lastly, of a decaying tooth in hemicrania, deprives the secondary part of these associated motions, namely, the exterior terminations of the bile-duct or urethra, or the pained membranes of the head in hemicrania, of their natural share of sensorial power: and hence the secondary parts of these sensitive trains of association become pained from the deficiency of their usual motions, which is accompanied with deficiency of secretions and of heat. See Sect. IV. 5. XII. 5. 3. XXXIV. 1. Why does the pain of the primary part of the association cease, when that of the secondary part commences? This is a question of intricacy, but perhaps not inexplicable. The pain of the primary part of these associated trains of motion was owing to too great stimulus, as of the stone at the neck of the bladder, and was consequently caused by too great action of the pained part. This greater action than natural of the primary part of these associated motions, by employing or expending the sensorial power of irritation belonging to the whole associated train of motions, occasioned torpor, and consequent pain in the secondary part of the associated train; which was possessed of greater sensibility than the primary part of it. Now the great pain of the secondary part of the train, as soon as it commences, employs or expends the sensorial power of sensation belonging to the whole associated train of motions; and in consequence the motions of the primary part, though increased by the stimulus of an extraneous body, cease to be accompanied with pain or sensation. If this mode of reasoning be just it explains a curious fact, why when two parts of the body are strongly stimulated, the pain is felt only in one of them, though it is possible by voluntary attention it may be alternately perceived in them both. In the same manner, when two new ideas are presented to us from the stimulus of external bodies, we attend to but one of them at a time. In other words, when one set of fibres, whether of the muscles or organs of sense, contract so strongly as to excite much sensation; another set of fibres contracting more weakly do not excite sensation at all, because the sensorial power of sensation is pre-occupied by the first set of fibres. So we cannot will more than one effect at once, though by associations previously formed we can move many fibres in combination. Thus in the instances above related, the termination of the bile duct in the duodenum, and the exterior extremity of the urethra, are more sensible than their other terminations. When these parts are deprived of their usual motions by deficiency of sensorial power, as above explained, they become painful according to law the fifth in Section IV. and the less pain originally excited by the stimulus of concreted bile, or of a stone at their other extremities ceases to be perceived. Afterwards, however, when the concretions of bile, or the stone on the urinary bladder, become more numerous or larger, the pain from their increased stimulus becomes greater than the associated pain; and is then felt at the neck of the gall bladder or urinary bladder; and the pain of the glans penis, or at the pit of the stomach, ceases to be perceived. 2. Examples of the second mode, where the increased action of the primary part of a train of sensitive association ceases, when that of the secondary part commences, are also not unfrequent; as this is the usual manner of the translation of inflammations from internal to external parts of the system, such as when an inflammation of the liver or stomach is translated to the membranes of the foot, and forms the gout; or to the skin of the face, and forms the rosy drop; or when an inflammation of the membranes of the kidneys is translated to the skin of the loins, and forms one kind of herpes, called shingles; in these cases by whatever cause the original inflammation may have been produced, as the secondary part of the train of sensitive association is more sensible, it becomes exerted with greater violence than the first part of it; and by both its increased pain, and the increased motion of its fibres, so far diminishes or exhausts the sensorial power of sensation; that the primary part of the train being less sensible ceases both to feel pain, and to act with unnatural energy. 3. Examples of the third mode, where the primary part of a train of sensitive association of motions may experience increased sensation, and the secondary part increased action, are likewise not unfrequent; as it is in this manner that most inflammations commence. Thus, after standing some time in snow, the feet become affected with the pain of cold, and a common coryza, or inflammation of the membrane of the nostrils, succeeds. It is probable that the internal inflammations, as pleurisies, or hepatitis, which are produced after the cold paroxysm of fever, originate in the same manner from the sympathy of those parts with some others, which were previously pained from quiescence; as happens to various parts of the system during the cold fits of fevers. In these cases it would seem, that the sensorial power of sensation becomes accumulated during the pain of cold, as the torpor of the vessels occasioned by the defect of heat contributes to the increase or accumulation of the sensorial power of irritation, and that both these become exerted on some internal part, which was not rendered torpid by the cold which affected the external parts, nor by its association with them; or which sooner recovered its sensibility. This requires further consideration. 4. An example of the fourth mode, or where the primary part of a sensitive association of motions may have increased action, and the secondary part increased sensation, may be taken from the pain of the shoulder, which attends inflammation of the membranes of the liver, see Class IV. 2. 2. 9.; in this circumstance so much sensorial power seems to be expended in the violent actions and sensations of the inflamed membranes of the liver, that the membranes associated with them become quiescent to their usual stimuli, and painful in consequence. There may be other modes in which the primary and secondary parts of the trains of associated sensitive motions may reciprocally affect each other, as may be seen by looking over Class IV. in the catalogue of diseases; all which may probably be resolved into the plus and minus of sensorial power, but we have not yet had sufficient observations made upon them with a view to this doctrine. III. The associated trains of our ideas may have sympathies, and their primary and secondary parts affect each other in some manner similar to those above described; and may thus occasion various curious phenomena not yet adverted to, besides those explained in the Sections on Dreams, Reveries, Vertigo, and Drunkenness; and may thus disturb the deductions of our reasonings, as well as the streams of our imaginations; present us with false degrees of fear, attach unfounded value to trivial circumstances; give occasion to our early prejudices and antipathies; and thus embarrass the happiness of our lives. A copious and curious harvest might be reaped from this province of science, in which, however, I shall not at present wield my sickle. * * * * * SECT. XXXVI. OF THE PERIODS OF DISEASES. I. _Muscles excited by volition soon cease to contract, or by sensation, or by irritation, owing to the exhaustion of sensorial power. Muscles subjected to less stimulus have their sensorial power accumulated. Hence the periods of some fevers. Want of irritability after intoxication._ II. 1. _Natural actions catenated with daily habits of life._ 2. _With solar periods. Periods of sleep. Of evacuating the bowels._ 3. _Natural actions catenated with lunar periods. Menstruation. Venereal orgasm of animals. Barrenness._ III. _Periods of diseased animal actions from stated returns of nocturnal cold, from solar and lunar influence. Periods of diurnal fever, hectic fever, quotidian, tertian, quartan fever. Periods of gout, pleurisy, of fevers with arterial debility, and with arterial strength, Periods of rhaphania, of nervous cough, hemicrania, arterial hæmorrhages, hæmorrhoids, hæmoptoe, epilepsy, palsy, apoplexy, madness._ IV. _Critical days depend on lunar periods. Lunar periods in the small pox._ I. If any of our muscles be made to contract violently by the power of volition, as those of the fingers, when any one hangs by his hands on a swing, fatigue soon ensues; and the muscles cease to act owing to the temporary exhaustion of the spirit of animation; as soon as this is again accumulated in the muscles, they are ready to contract again by the efforts of volition. Those violent muscular actions induced by pain become in the same manner intermitted and recurrent; as in labour-pains, vomiting, tenesmus, strangury; owing likewise to the temporary exhaustion of the spirit of animation, as above mentioned. When any stimulus continues long to act with unnatural violence, so as to produce too energetic action of any of our moving organs, those motions soon cease, though the stimulus continues to act; as in looking long on a bright object, as on an inch-square of red silk laid on white paper in the sunshine. See Plate I. in Sect. III. 1. On the contrary, where less of the stimulus of volition, sensation, or irritation, have been applied to a muscle than usual; there appears to be an accumulation of the spirit of animation in the moving organ; by which it is liable to act with greater energy from less quantity of stimulus, than was previously necessary to excite it into so great action; as after having been immersed in snow the cutaneous vessels of our hands are excited into stronger action by the stimulus of a less degree of heat, than would previously have produced that effect. From hence the periods of some fever-fits may take their origin, either simply, or by their accidental coincidence with lunar and solar periods, or with the diurnal periods of heat and cold, to be treated of below; for during the cold fit at the commencement of a fever, from whatever cause that cold fit may have been induced, it follows, 1. That the spirit of animation must become accumulated in the parts, which exert during this cold fit less than their natural quantity of action. 2. If the cause producing the cold fit does not increase, or becomes diminished; the parts before benumbed or inactive become now excitable by smaller stimulus, and are thence thrown into more violent action than is natural; that is a hot fit succeeds the cold one. 3. By the energetic action of the system during the hot fit, if it continues long, an exhaustion of the spirit of animation takes place; and another cold fit is liable to succeed, from the moving system not being excitable into action from its usual stimulus. This inirritability of the system from a too great previous stimulus, and consequent exhaustion of sensorial power, is the cause of the general debility, and sickness, and head-ach, some hours after intoxication. And hence we see one of the causes of the periods of fever-fits; which however are frequently combined with the periods of our diurnal habits, or of heat and cold, or of solar or lunar periods. When besides the tendency to quiescence occasioned by the expenditure of sensorial power during the hot fit of fever, some other cause of torpor, as the solar or lunar periods, is necessary to the introduction of a second cold fit; the fever becomes of the intermittent kind; that is, there is a space of time intervenes between the end of the hot fit, and the commencement of the next cold one. But where no exteriour cause is necessary to the introduction of the second cold fit; no such interval of health intervenes; but the second cold fit commences, as soon as the sensorial power is sufficiently exhausted by the hot fit; and the fever becomes continual. II. 1. The following are natural animal actions, which are frequently catenated with our daily habits of life, as well as excited by their natural irritations. The periods of hunger and thirst become catenated with certain portions of time, or degrees of exhaustion, or other diurnal habits of life. And if the pain of hunger be not relieved by taking food at the usual time, it is liable to cease till the next period of time or other habits recur; this is not only true in respect to our general desire of food, but the kinds of it also are governed by this periodical habit; insomuch that beer taken to breakfast will disturb the digestion of those, who have been accustomed to tea; and tea taken at dinner will disagree with those, who have been accustomed to beer. Whence it happens, that those, who have weak stomachs, will be able to digest more food, if they take their meals at regular hours; because they have both the stimulus of the aliment they take, and the periodical habit, to assist their digestion. The periods of emptying the bladder are not only dependent on the acrimony or distention of the water in it, but are frequently catenated with external cold applied to the skin, as in cold bathing, or washing the hands; or with other habits of life, as many are accustomed to empty the bladder before going to bed, or into the house after a journey, and this whether it be full or not. Our times of respiration are not only governed by the stimulus of the blood in the lungs, or our desire of fresh air, but also by our attention to the hourly objects before us. Hence when a person is earnestly contemplating an idea of grief, he forgets to breathe, till the sensation in his lungs becomes very urgent; and then a sigh succeeds for the purpose of more forceably pushing forwards the blood, which is accumulated in the lungs. Our times of respiration are also frequently governed in part by our want of a steady support for the actions of our arms, and hands, as in threading a needle, or hewing wood, or in swimming; when we are intent upon these objects, we breathe at the intervals of the exertion of the pectoral muscles. 2. The following natural animal actions are influenced by solar periods. The periods of sleep and of waking depend much on the solar period, for we are inclined to sleep at a certain hour, and to awake at a certain hour, whether we have had more or less fatigue during the day, if within certain limits; and are liable to wake at a certain hour, whether we went to bed earlier or later, within certain limits. Hence it appears, that those who complain of want of sleep, will be liable to sleep better or longer, if they accustom themselves to go to rest, and to rise, at certain hours. The periods of evacuating the bowels are generally connected with some part of the solar day, as well as with the acrimony or distention occasioned by the feces. Hence one method of correcting costiveness is by endeavouring to establish a habit of evacuation at a certain hour of the day, as recommended by Mr. Locke, which may be accomplished by using daily voluntary efforts at those times, joined with the usual stimulus of the material to be evacuated. 3. The following natural animal actions are connected with lunar periods. 1. The periods of female menstruation are connected with lunar periods to great exactness, in some instances even to a few hours. These do not commence or terminate at the full or change, or at any other particular part of the lunation, but after they have commenced at any part of it, they continue to recur at that part with great regularity, unless disturbed by some violent circumstance, as explained in Sect. XXXII. No. 6. their return is immediately caused by deficient venous absorption, which is owing to the want of the stimulus, designed by nature, of amatorial copulation, or of the growing fetus. When the catamenia returns sooner than the period of lunation, it shows a tendency of the constitution to inirritability; that is to debility, or deficiency of sensorial power, and is to be relieved by small doses of steel and opium. The venereal orgasm of birds and quadrupeds seems to commence, or return about the most powerful lunations at the vernal or autumnal equinoxes; but if it be disappointed of its object, it is said to recur at monthly periods; in this respect resembling the female catamenia. Whence it is believed, that women are more liable to become pregnant at or about the time of their catamenia, than at the intermediate times; and on this account they are seldom much mistaken in their reckoning of nine lunar periods from the last menstruation; the inattention to this may sometimes have been the cause of supposed barrenness, and is therefore worth the observation of those, who wish to have children. III. We now come to the periods of diseased animal actions. The periods of fever-fits, which depend on the stated returns of nocturnal cold, are discussed in Sect. XXXII. 3. Those, which originate or recur at solar or lunar periods, are also explained in Section XXXII. 6. These we shall here enumerate; observing, however, that it is not more surprising, that the influence of the varying attractions of the sun and moon, should raise the ocean into mountains, than that it should affect the nice sensibilities of animal bodies; though the manner of its operation on them is difficult to be understood. It is probable however, that as this influence gradually lessens during the course of the day, or of the lunation, or of the year, some actions of our system become less and less; till at length a total quiescence of some part is induced; which is the commencement of the paroxysms of fever, of menstruation, of pain with decreased action of the affected organ, and of consequent convulsion. 1. A diurnal fever in some weak people is distinctly observed to come on towards evening, and to cease with a moist skin early in the morning, obeying the solar periods. Persons of weak constitutions are liable to get into better spirits at the access of the hot fit of this evening fever; and are thence inclined to sit up late; which by further enfeebling them increases the disease; whence they lose their strength and their colour. 2. The periods of hectic fever, supposed to arise from absorption of matter, obeys the diurnal periods like the above, having the exacerbescence towards evening, and its remission early in the morning, with sweats, or diarrhoea, or urine with white sediment. 3. The periods of quotidian fever are either catenated with solar time, and return at the intervals of twenty-four hours; or with lunar time, recurring at the intervals of about twenty-five hours. There is great use in knowing with what circumstances the periodical return or new morbid motions are conjoined, as the most effectual times of exhibiting the proper medicines are thus determined. So if the torpor, which ushers in an ague fit, is catenated with the lunar day: it is known, when the bark or opium must be given, so as to exert its principal effect about the time of the expected return. Solid opium should be given about an hour before the expected cold fit; liquid opium and wine about half an hour; the bark repeatedly for six or eight hours previous to the expected return. 4. The periods of tertian fevers, reckoned from the commencement of one cold fit to the commencement of the next cold fit, recur with solar intervals of forty-eight hours, or with lunar ones of about fifty hours. When these of recurrence begin one or two hours earlier than the solar period, it shews, that the torpor or cold fit is produced by less external influence; and therefore that it is more liable to degenerate into a fever with only remissions; so when menstruation recurs sooner than the period of lunation, it shews a tendency of the habit to torpor of inirritability. 5. The periods of quartan fevers return at solar intervals of seventy-two hours, or at lunar ones of about seventy-four hours and an half. This kind of ague appears most in moist cold autumns, and in cold countries replete with marshes. It is attended with greater debility, and its cold access more difficult to prevent. For where there is previously a deficiency of sensorial power, the constitution is liable to run into greater torpor from any further diminution of it; two ounces of bark and some steel should be given on the day before the return of the cold paroxysm, and a pint of wine by degrees a few hours before its return, and thirty drops of laudanum one hour before the expected cold fit. 6. The periods of the gout generally commence about an hour before sun-rise, which is usually the coldest part of the twenty-four hours. The greater periods of the gout seem also to observe the solar influence, returning about the same season of the year. 7. The periods of the pleurisy recur with exacerbation of the pain and fever about sun-set, at which time venesection is of most service. The same may be observed of the inflammatory rheumatism, and other fevers with arterial strength, which seem to obey solar periods; and those with debility seem to obey lunar ones. 8. The periods of fevers with arterial debility seem to obey the lunar day, having their access daily nearly an hour later; and have sometimes two accesses in a day, resembling the lunar effects upon the tides. 9. The periods of rhaphania, or convulsions of the limbs from rheumatic pains, seem to be connected with solar influence, returning at nearly the same hour for weeks together, unless disturbed by the exhibition of powerful doses of opium. So the periods of Tussis ferina, or violent cough with slow pulse, called nervous cough, recurs by solar periods. Five grains of opium, given at the time the cough commenced disturbed the period, from seven in the evening to eleven, at which time it regularly returned for some days, during which time the opium was gradually omitted. Then 120 drops of laudanum were given an hour before the access of the cough, and it totally ceased. The laudanum was continued a fortnight, and then gradually discontinued. 10. The periods of hemicrania, and of painful epilepsy, are liable to obey lunar periods, both in their diurnal returns, and in their greater periods of weeks, but are also induced by other exciting causes. 11. The periods of arterial hæmorrhages seem to return at solar periods about the same hour of the evening or morning. Perhaps the venous hæmorrhages obey the lunar periods, as the catamenia, and hæmorrhoids. 12. The periods of the hæmorrhoids, or piles, in some recur monthly, in others only at the greater lunar influence about the equinoxes. 13. The periods of hæmoptoe sometimes obey solar influence, recurring early in the morning for several days; and sometimes lunar periods, recurring monthly; and sometimes depend on our hours of sleep. See Class I. 2. 1. 9. 14. Many of the first periods of epileptic fits obey the monthly lunation with some degree of accuracy; others recur only at the most powerful lunations before the vernal equinox, and after the autumnal one; but when the constitution has gained a habit of relieving disagreeable sensations by this kind of exertion, the fit recurs from any slight cause. 15. The attack of palsy and apoplexy are known to recur with great frequency about the equinoxes. 16. There are numerous instances of the effect of the lunations upon the periods of insanity, whence the name of lunatic has been given to those afflicted with this disease. IV. The critical days, in which fevers are supposed to terminate, have employed the attention of medical philosophers from the days of Hippocrates to the present time. In whatever part of a lunation a fever commences, which owes either its whole cause to solar and lunar influence, or to this in conjunction with other causes; it would seem, that the effect would be the greatest at the full and new moon, as the tides rise highest at those times, and would be the least at the quadratures; thus if a fever-fit should commence at the new or full moon, occasioned by the solar and lunar attraction diminishing some chemical affinity of the particles of blood, and thence decreasing their stimulus on our sanguiferous system, as mentioned in Sect. XXXII. 6. this effect will daily decrease for the first seven days, and will then increase till about the fourteenth day, and will again decrease till about the twenty-first day, and increase again till the end of the lunation. If a fever-fit from the above cause should commence on the seventh day after either lunation, the reverse of the above circumstances would happen. Now it is probable, that those fevers, whose crisis or terminations are influenced by lunations, may begin at one or other of the above times, namely at the changes or quadratures; though sufficient observations have not been made to ascertain this circumstance. Hence I conclude, that the small-pox and measles have their critical days, not governed by the times required for certain chemical changes in the blood, which affect or alter the stimulus of the contagious matter, but from the daily increasing or decreasing effect of this lunar link of catenation, as explained in Section XVII. 3. 3. And as other fevers terminate most frequently about the seventh, fourteenth, twenty-first, or about the end of four weeks, when no medical assistance has disturbed their periods, I conclude, that these crises, or terminations, are governed by periods of the lunations; though we are still ignorant of their manner of operation. In the distinct small-pox the vestiges of lunation are very apparent, after inoculation a quarter of a lunation precedes the commencement of the fever, another quarter terminates with the complete eruption, another quarter with the complete maturation, and another quarter terminates the complete absorption of a material now rendered inoffensive to the constitution. * * * * * SECT. XXXVII. OF DIGESTION, SECRETION, NUTRITION. I. _Crystals increase by the greater attraction of their sides. Accretion by chemical precipitations, by welding, by pressure, by agglutination._ II. _Hunger, digestion, why it cannot be imitated out of the body. Lacteals absorb by animal selection or appetency._ III. _The glands and pores absorb nutritious particles by animal selection. Organic particles of Buffon. Nutrition applied at the time of elongation of fibres. Like inflammation._ IV. _It seems easier to have preserved animals than to reproduce them. Old age and death from inirritability. Three causes of this. Original fibres of the organs of sense and muscles unchanged._ V. _Art of producing long life._ I. The larger crystals of saline bodies may be conceived to arise from the combination of smaller crystals of the same form, owing to the greater attractions of their sides than of their angles. Thus if four cubes were floating in a fluid, whose friction or resistance is nothing, it is certain the sides of these cubes would attract each other stronger than their angles; and hence that these four smaller cubes would so arrange themselves as to produce one larger one. There are other means of chemical accretion, such as the depositions of dissolved calcareous or siliceous particles, as are seen in the formation of the stalactites of limestone in Derbyshire, or of calcedone in Cornwall. Other means of adhesion are produced by heat and pressure, as in the welding of iron-bars; and other means by simple pressure, as in forcing two pieces of caoutchou, or elastic gum, to adhere; and lastly, by the agglutination of a third substance penetrating the pores of the other two, as in the agglutination of wood by means of animal gluten. Though the ultimate particles of animal bodies are held together during life, as well as after death, by their specific attraction of cohesion, like all other matter; yet it does not appear, that their original organization was produced by chemical laws, and their production and increase must therefore only be looked for from the laws of animation. II. When the pain of hunger requires relief, certain parts of the material world, which surround us, when applied to our palates, excite into action the muscles of deglutition; and the material is swallowed into the stomach. Here the new aliment becomes mixed with certain animal fluids, and undergoes a chemical process, termed digestion; which however chemistry has not yet learnt to imitate out of the bodies of living animals or vegetables. This process seems very similar to the saccharine process in the lobes of farinaceous seeds, as of barley, when it begins to germinate; except that, along with the sugar, oil and mucilage are also produced; which form the chyle of animals, which is very similar to their milk. The reason, I imagine, why this chyle-making, or saccharine process, has not yet been imitated by chemical operations, is owing to the materials being in such a situation in respect to warmth, moisture, and motion; that they will immediately change into the vinous or acetous fermentation; except the new sugar be absorbed by the numerous lacteal or lymphatic vessels, as soon as it is produced; which is not easy to imitate in the laboratory. These lacteal vessels have mouths, which are irritated into action by the stimulus of the fluid, which surrounds them; and by animal selection, or appetency, they absorb such part of the fluid as is agreeable to their palate; those parts, for instance, which are already converted into chyle, before they have time to undergo another change by a vinous or acetous fermentation. This animal absorption of fluid is almost visible to the naked eye in the action of the puncta lacrymalia; which imbibe the tears from the eye, and discharge them again into the nostrils. III. The arteries constitute another reservoir of a changeful fluid; from which, after its recent oxygenation in the lungs, a further animal selection of various fluids is absorbed by the numerous glands; these select their respective fluids from the blood, which is perpetually undergoing a chemical change; but the selection by these glands, like that of the lacteals, which open their mouths into the digesting aliment in the stomach, is from animal appetency, not from chemical affinity; secretion cannot therefore be imitated in the laboratory, as it consists in a selection of part of a fluid during the chemical change of that fluid. The mouths of the lacteals, and lymphatics, and the ultimate terminations of the glands, are finer than can easily be conceived; yet it is probable, that the pores, or interstices of the parts, or coats, which constitute these ultimate vessels, may still have greater tenuity; and that these pores from the above analogy must posses a similar power of irritability, and absorb by their living energy the particles of fluid adapted to their purposes, whether to replace the parts abraded or dissolved, or to elongate and enlarge themselves. Not only every kind of gland is thus endued with its peculiar appetency, and selects the material agreeable to its taste from the blood, but every individual pore acquires by animal selection the material, which it wants; and thus nutrition seems to be performed in a manner so similar to secretion; that they only differ in the one retaining, and the other parting again with the particles, which they have selected from the blood. This way of accounting for nutrition from stimulus, and the consequent animal selection of particles, is much more analogous to other phenomena of the animal microcosm, than by having recourse to the microscopic animalcula, or organic particles of Buffon, and Needham; which being already compounded must themselves require nutritive particles to continue their own existence. And must be liable to undergo a change by our digestive or secretory organs; otherwise mankind would soon resemble by their theory the animals, which they feed upon. He, who is nourished by beef or venison, would in time become horned; and he, who feeds on pork or bacon, would gain a nose proper for rooting into the earth, as well as for the perception of odours. The whole animal system may be considered as consisting of the extremities of the nerves, or of having been produced from them; if we except perhaps the medullary part of the brain residing in the head and spine, and in the trunks of the nerves. These extremities of the nerves are either of those of locomotion, which are termed muscular fibres; or of those of sensation, which constitute the immediate organs of sense, and which have also their peculiar motions. Now as the fibres, which constitute the bones and membranes, possessed originally sensation and motion; and are liable again to possess them, when they become inflamed; it follows, that those were, when first formed, appendages to the nerves of sensation or locomotion, or were formed from them. And that hence all these solid parts of the body, as they have originally consisted of extremities of nerves, require an apposition of nutritive particles of a similar kind, contrary to the opinion of Buffon and Needham above recited. Lastly, as all these filaments have possessed, or do possess, the power of contraction, and of consequent inertion or elongation; it seems probable, that the nutritive particles are applied during their times of elongation; when their original constituent particles are removed to a greater distance from each other. For each muscular or sensual fibre may be considered as a row or string of beads; which approach, when in contraction, and recede during its rest or elongation; and our daily experience shews us, that great action emaciates the system, and that it is repaired during rest. Something like this is seen out of the body; for if a hair, or a single untwisted fibre of flax or silk, be soaked in water; it becomes longer and thicker by the water, which is absorbed into its pores. Now if a hair could be supposed to be thus immersed in a solution of particles similar to those, which compose it; one may imagine, that it might be thus increased in weight and magnitude; as the particles of oak-bark increase the substance of the hides of beasts in the process of making leather. I mention these not as philosophic analogies, but as similes to facilitate our ideas, how an accretion of parts may be effected by animal appetences, or selections, in a manner somewhat similar to mechanical or chemical attractions. If those new particles of matter, previously prepared by digestion and sanguification, only supply the places of those, which have been abraded by the actions of the system, it is properly termed nutrition. If they are applied to the extremities of the nervous fibrils, or in such quantity as to increase the length or crassitude of them, the body becomes at the same time enlarged, and its growth is increased, as well as its deficiences repaired. In this last case something more than a simple apposition or selection of particles seems to be necessary; as many parts of the system during its growth are caused to recede from those, with which they were before in contact; as the ends of the bones, or cartilages, recede from each other, as their growth advances: this process resembles inflammation, as appears in ophthalmy, or in the production of new flesh in ulcers, where old vessels are enlarged, and new ones produced; and like that is attended with sensation. In this situation the vessels become distended with blood, and acquire greater sensibility, and may thus be compared to the erection of the penis, or of the nipples of the breasts of women; while new particles become added at the same time; as in the process of nutrition above described. When only the natural growth of the various parts of the body are produced, a pleasurable sensation attends it, as in youth, and perhaps in those, who are in the progress of becoming fat. When an unnatural growth is the consequence, as in inflammatory diseases, a painful sensation attends the enlargement of the system. IV. This apposition of new parts, as the old ones disappear, selected from the aliment we take, first enlarges and strengthens our bodies for twenty years, for another twenty years it keeps us in health and vigour, and adds strength and solidity to the system; and then gradually ceases to nourish us properly, and for another twenty years we gradually sink into decay, and finally cease to act, and to exist. On considering this subject one should have imagined at first view, that it might have been easier for nature to have supported her progeny for ever in health and life, than to have perpetually reproduced them by the wonderful and mysterious process of generation. But it seems our bodies by long habit cease to obey the stimulus of the aliment, which should support us. After we have acquired our height and solidity we make no more new parts, and the system obeys the irritations, sensations, volitions; and associations, with, less and less energy, till the whole sinks into inaction. Three causes may conspire to render our nerves less excitable, which have been already mentioned, 1. If a stimulus be greater than natural, it produces too great an exertion of the stimulated organ, and in consequence exhausts the spirit of animation; and the moving organ ceases to act, even though the stimulus be continued. And though rest will recruit this exhaustion, yet some degree of permanent injury remains, as is evident after exposing the eyes long to too strong a light. 2. If excitations weaker than natural be applied, so as not to excite the organ into action, (as when small doses of aloe or rhubarb are exhibited,) they may be gradually increased, without exciting the organ into action; which will thus acquire a habit of disobedience to the stimulus; thus by increasing the dose by degrees, great quantities of opium or wine may be taken without intoxication. See Sect. XII. 3. 1. 3. Another mode, by which life is gradually undermined, is when irritative motions continue to be produced in consequence of stimulus, but are not succeeded by sensation; hence the stimulus of contagious matter is not capable of producing fever a second time, because it is not succeeded by sensation. See Sect. XII. 3. 6. And hence, owing to the want of the general pleasurable sensation, which ought to attend digestion and glandular secretion, an irksomeness of life ensues; and, where this is in greater excess, the melancholy of old age occurs, with torpor or debility. From hence I conclude, that it is probable that the fibrillæ, or moving filaments at the extremities of the nerves of sense, and the fibres which constitute the muscles (which are perhaps the only parts of the system that are endued with contractile life) are not changed, as we advance in years, like the other parts of the body; but only enlarged or elongated with our growth; and in consequence they become less and less excitable into action. Whence, instead of gradually changing the old animal, the generation of a totally new one becomes necessary with undiminished excitability; which many years will continue to acquire new parts, or new solidity, and then losing its excitability in time, perish like its parent. V. From this idea the art of preserving long health and life may be deduced; which must consist in using no greater stimulus, whether of the quantity or kind of our food and drink, or of external circumstances, such as heat, and exercise, and wakefulness, than is sufficient to preserve us in vigour; and gradually, as we grow old to increase the stimulus of our aliment, as the irritability of our system increases. The debilitating effects ascribed by the poet MARTIAL to the excessive use of warm bathing in Italy, may with equal propriety be applied to the warm rooms of England; which, with the general excessive stimulus of spirituous or fermented liquors, and in some instances of immoderate venery, contribute to shorten our lives. _Balnea, vina, venus, corrumpunt corpora nostra_, _At faciunt vitam balnea, vina, venus!_ Wine, women, warmth, against our lives combine; But what is life without warmth, women, wine! * * * * * SECT. XXXVIII. OF THE OXYGENATION OF THE BLOOD IN THE LUNGS, AND IN THE PLACENTA. I. _Blood absorbs oxygene from the air, whence phosphoric acid changes its colour, gives out heat, and some phlogistic material, and acquires an ethereal spirit, which is dissipated in fibrous motion._ II. _The placenta is a pulmonary organ like the gills of fish. Oxygenation of the blood from air, from water, by lungs, by gills, by the placenta; necessity of this oxygenation to quadrupeds, to fish, to the foetus in utero. Placental vessels inserted into the arteries of the mother. Use of cotyledons in cows. Why quadrupeds have not sanguiferous lochia. Oxygenation of the chick in the egg, of feeds._ III. _The liquor amnii is not excrementitious. It is nutritious. It is found in the esophagus and stomach, and forms the meconium. Monstrous births without heads. Question of Dr. Harvey._ I. From the recent discoveries of many ingenious philosophers it appears, that during respiration the blood imbibes the vital part of the air, called oxygene, through the membranes of the lungs; and that hence respiration may be aptly compared to a slow combustion. As in combustion the oxygene of the atmosphere unites with some phlogistic or inflammable body, and forms an acid (as in the production of vitriolic acid from sulphur, or carbonic acid from charcoal,) giving out at the same time a quantity of the matter of heat; so in respiration the oxygene of the air unites with the phlogistic part of the blood, and probably produces phosphoric or animal acid, changing the colour of the blood from a dark to a bright red; and probably some of the matter of heat is at the same time given out according to the theory of Dr. Crawford. But as the evolution of heat attends almost all chemical combinations, it is probable, that it also attends the secretions of the various fluids from the blood; and that the constant combinations or productions of new fluids by means of the glands constitute the more general source of animal heat; this seems evinced by the universal evolution of the matter of heat in the blush of shame or of anger; in which at the same time an increased secretion of the perspirable matter occurs; and the partial evolution of it from topical inflammations, as in gout or rheumatism, in which there is a secretion of new blood-vessels. Some medical philosophers have ascribed the heat of animal bodies to the friction of the particles of the blood against the sides of the vessels. But no perceptible heat has ever been produced by the agitation of water, or oil, or quicksilver, or other fluids; except those fluids have undergone at the same time some chemical change, as in agitating milk or wine, till they become sour. Besides the supposed production of phosphoric acid, and change of colour of the blood, and the production of carbonic acid, there would appear to be something of a more subtile nature perpetually acquired from the atmosphere; which is too fine to be long contained in animal vessels, and therefore requires perpetual renovation; and without which life cannot continue longer than a minute or two; this ethereal fluid is probably secreted from the blood by the brain, and perpetually dissipated in the actions of the muscles and organs of sense. That the blood acquires something from the air, which is immediately necessary to life, appears from an experiment of Dr. Hare (Philos. Transact. abridged, Vol. III. p. 239.) who found, "that birds, mice, &c. would live as long again in a vessel, where he had crowded in double the quantity of air by a condensing engine, than they did when confined in air of the common density." Whereas if some kind of deleterious vapour only was exhaled from the blood in respiration; the air, when condensed into half its compass, could not be supposed to receive so much of it. II. Sir Edward Hulse, a physician of reputation at the beginning of the present century, was of opinion, that the placenta was a respiratory organ, like the gills of fish; and not an organ to supply nutriment to the foetus; as mentioned in Derham's Physico-theology. Many other physicians seem to have espoused the same opinion, as noticed by Haller. Elem. Physiologiæ, T. 1. Dr. Gipson published a defence of this theory in the Medical Essays of Edinburgh, Vol. I. and II. which doctrine is there controverted at large by the late Alexander Monro; and since that time the general opinion has been, that the placenta is an organ of nutrition only, owing perhaps rather to the authority of so great a name, than to the validity of the arguments adduced in its support. The subject has lately been resumed by Dr. James Jeffray, and by Dr. Forester French, in their inaugural dissertations at Edinburgh and at Cambridge; who have defended the contrary opinion in an able and ingenious manner; and from whose Theses I have extracted many of the following remarks. First, by the late discoveries of Dr. Priestley, M. Lavoisier, and other philosophers, it appears, that the basis of atmospherical air, called oxygene, is received by the blood through the membranes of the lungs; and that by this addition the colour of the blood is changed from a dark to a light red. Secondly, that water possesses oxygene also as a part of its composition, and contains air likewise in its pores; whence the blood of fish receives oxygene from the water, or from the air it contains, by means of their gills, in the same manner as the blood is oxygenated in the lungs of air-breathing animals; it changes its colour at the same time from a dark to a light red in the vessels of their gills, which constitute a pulmonary organ adapted to the medium in which they live. Thirdly, that the placenta consists of arteries carrying the blood to its extremities, and a vein bringing it back, resembling exactly in structure the lungs and gills above mentioned; and that the blood changes its colour from a dark to a light red in passing through these vessels. This analogy between the lungs and gills of animals, and the placenta of the fetus, extends through a great variety of other circumstances; thus air-breathing creatures and fish can live but a few minutes without air or water; or when they are confined in such air or water, as has been spoiled by their own respiration; the same happens to the fetus, which, as soon as the placenta is separated from the uterus, must either expand its lungs, and receive air, or die. Hence from the structure, as well as the use of the placenta, it appears to be a respiratory organ, like the gills of fish, by which the blood in the fetus becomes oxygenated. From the terminations of the placental vessels not being observed to bleed after being torn from the uterus, while those of the uterus effuse a great quantity of florid arterial blood, the terminations of the placental vessels would seem to be inserted into the arterial ones of the mother; and to receive oxygenation from the passing currents of her blood through their coats or membranes; which oxygenation is proved by the change of the colour of the blood from dark to light red in its passage from the placental arteries to the placental vein. The curious structure of the cavities or lacunæ of the placenta, demonstrated by Mr. J. Hunter, explain this circumstance. That ingenious philosopher has shewn, that there are numerous cavities of lacunæ formed on that side of the placenta, which is in contact with the uterus; those cavities or cells are filled with blood from the maternal arteries, which open into them; which blood is again taken up by the maternal veins, and is thus perpetually changed. While the terminations of the placental arteries and veins are spread in fine reticulation on the sides of these cells. And thus, as the growing fetus requires greater oxygenation, an apparatus is produced resembling exactly the air-cells of the lungs. In cows, and other ruminating animals, the internal surface of the uterus is unequal like hollow cups, which have been called cotyledons; and into these cavities the prominencies of the numerous placentas, with which the fetus of those animals is furnished, are inserted, and strictly adhere; though they may be extracted without effusion of blood. These inequalities of the uterus, and the numerous placentas in consequence, seem to be designed for the purpose of expanding a greater surface for the terminations of the placental vessels for the purpose of receiving oxygenation from the uterine ones; as the progeny of this class of animals are more completely formed before their nativity, than that of the carnivorous classes, and must thence in the latter weeks of pregnancy require greater oxygenation. Thus calves and lambs can walk about in a few minutes after their birth; while puppies and kittens remain many days without opening their eyes. And though on the separation of the cotyledons of ruminating animals no blood is effused, yet this is owing clearly to the greater power of contraction of their uterine lacunæ or alveoli. See Medical Essays, Vol. V. page 144. And from the same cause they are not liable to a sanguiferous menstruation. The necessity of the oxygenation of the blood in the fetus is farther illustrated by the analogy of the chick in the egg; which appears to have its blood oxygenated at the extremities of the vessels surrounding the yolk; which are spread on the air-bag at the broad end of the egg, and may absorb oxygene through that moist membrane from the air confined behind it; and which is shewn by experiments in the exhausted receiver to be changeable though the shell. This analogy may even be extended to the growing seeds of vegetables; which were shewn by Mr. Scheele to require a renovation of the air over the water, in which they were confined. Many vegetable seeds are surrounded with air in their pods or receptacles, as peas, the fruit of staphylea, and lichnis vesicaria; but it is probable, that those seeds, after they are shed, as well as the spawn of fish, by the situation of the former on or near the moist and aerated surface of the earth, and of the latter in the ever-changing and ventilated water, may not be in need of an apparatus for the oxygenation of their first blood, before the leaves of one, and the gills of the other, are produced for this purpose. III. 1. There are many arguments, besides the strict analogy between the liquor amnii and the albumen ovi, which shew the former to be a nutritive fluid; and that the fetus in the latter months of pregnancy takes it into its stomach; and that in consequence the placenta is produced for some other important purpose. First, that the liquor amnii is not an excrementitious fluid is evinced, because it is found in greater quantity, when the fetus is young, decreasing after a certain period till birth. Haller asserts, "that in some animals but a small quantity of this fluid remains at the birth. In the eggs of hens it is consumed on the eighteenth day, so that at the exclusion of the chick scarcely any remains. In rabbits before birth there is none." Elem. Physiol. Had this been an excrementitious fluid, the contrary would probably have occurred. Secondly, the skin of the fetus is covered with a whitish crust or pellicle, which would seem to preclude any idea of the liquor amnii being produced by any exsudation of perspirable matter. And it cannot consist of urine, because in brute animals the urachus passes from the bladder to the alantois for the express purpose of carrying off that fluid; which however in the human fetus seems to be retained in the distended bladder, as the feces are accumulated in the bowels of all animals. 2. The nutritious quality of the liquid, which surrounds the fetus, appears from the following considerations. 1. It is coagulable by heat, by nitrous acid, and by spirit of wine, like milk, serum of blood, and other fluids, which daily experience evinces to be nutritious. 2. It has a saltish taste according to the accurate Baron Haller, not unlike the whey of milk, which it even resembles in smell. 3. The white of the egg which constitutes the food of the chick, is shewn to be nutritious by our daily experience; besides the experiment of its nutritious effects mentioned by Dr. Fordyce in his late Treatise on Digestion, p. 178; who adds, that it much resembles the essential parts of the serum of blood. 3. A fluid similar to the fluid, with which the fetus is surrounded, except what little change may be produced by a beginning digestion, is found in the stomach of the fetus; and the white of the egg is found, in the same manner in the stomach of the chick. Numerous hairs, similar to those of its skin, are perpetually found among the contents of the stomach in new-born calves; which must therefore have licked themselves before their nativity. Blasii Anatom. See Sect. XVI. 2. on Instinct. The chick in the egg is seen gently to move in its surrounding fluid, and to open and shut its mouth alternately. The same has been observed in puppies. Haller's El. Phys. I. 8. p. 201. A column of ice has been seen to reach down the oesophagus from the mouth to the stomach in a frozen fetus; and this ice was the liquor amnii frozen. The meconium, or first fæces, in the bowels of new-born infants evince, that something has been digested; and what could this be but the liquor amnii together with the recrements of the gastric juice and gall, which were necessary for its digestion? There have been recorded some monstrous births of animals without heads, and consequently without mouths, which seem to have been delivered on doubtful authority, or from inaccurate observation. There are two of such monstrous productions however better attested; one of a human fetus, mentioned by Gipson in the Scots Medical Essays; which having the gula impervious was furnished with an aperture into the wind-pipe, which communicated below into the gullet; by means of which the liquor amnii might be taken into the stomach before nativity without danger of suffocation, while the fetus had no occasion to breathe. The other monstrous fetus is described by Vander Wiel, who asserts, that he saw a monstrous lamb, which had no mouth; but instead of it was furnished with an opening in the lower part of the neck into the stomach. Both these instances evidently favour the doctrine of the fetus being nourished by the mouth; as otherwise there had been no necessity for new or unnatural apertures into the stomach, when the natural ones were deficient? From these facts and observations we may safely infer, that the fetus in the womb is nourished by the fluid which surrounds it; which during the first period of gestation is absorbed by the naked lacteals; and is afterwards swallowed into the stomach and bowels, when these organs are perfected; and lastly that the placenta is an organ for the purpose of giving due oxygenation to the blood of the fetus; which is more necessary, or at least more frequently necessary, than even the supply of food. The question of the great Harvey becomes thus easily answered. "Why is not the fetus in the womb suffocated for want of air, when it remains there even to the tenth month without respiration: yet if it be born in the seventh or eighth month, and has once respired, it becomes immediately suffocated for want of air, if its respiration be obstructed?" For further information on this subject, the reader is referred to the Tentamen Medicum of Dr. Jeffray, printed at Edinburgh in 1786. And it is hoped that Dr. French will some time give his theses on this subject to the public. * * * * * SECT. XXXIX. OF GENERATION. Felix, qui causas altà caligine mersas Pandit, et evolvit tenuissima vincula rerum. I. _Habits of acting and feeling of individuals attend the soul into a future life, and attend the new embryon at the time of its production. The new speck of entity absorbs nutriment, and receives oxygene. Spreads the terminations of its vessels on cells, which communicate with the arteries of the uterus; sometimes with those of the peritoneum. Afterwards it swallows the liquor amnii, which it produces by its irritation from the uterus, or peritoneum. Like insects in the heads of calves and sheep. Why the white of egg is of two consistencies. Why nothing is found in quadrupeds similar to the yolk, nor in most vegetable seeds._ II. 1. _Eggs of frogs and fish impregnated out of their bodies. Eggs of fowls which are not fecundated, contain only the nutriment for the embryon. The embryon is produced by the male, and the nutriment by the female. Animalcula in semine. Profusion of nature's births._ 2. _Vegetables viviparous. Buds and bulbs have each a father but no mother. Vessels of the leaf and bud inosculate. The paternal offspring exactly resembles the parent._ 3. _Insects impregnated for six generations. Polypus branches like buds. Creeping roots. Viviparous flowers. Tænia, volvox. Eve from Adam's rib. Semen not a stimulus to the egg._ III. 1. _Embryons not originally created within other embryons. Organized matter is not so minute._ 2. _All the parts of the embryon are not formed in the male parent. Crabs produce their legs, worms produce their heads and tails. In wens, cancers, and inflammations, new vessels are formed. Mules partake of the forms of both parents. Hair and nails grow by elongation, not by distention._ 3. _Organic particles of Buffon._ IV. 1. _Rudiment of the embryon a simple living filament, becomes a living ring, and then a living tube._ 2. _It acquires irritabilities, and sensibilities with new organizations, as in wounded snails, polypi, moths, gnats, tadpoles. Hence new parts are acquired by addition not by distention._ 3. _All parts of the body grow if not confined._ 4. _Fetuses deficient at their extremities, or have a duplicature of parts. Monstrous births. Double parts of vegetables._ 5. _Mules cannot be formed by distention of the seminal ens._ 6. _Families of animals from a mixture of their orders. Mules imperfect._ 7. _Animal appetency like chemical affinity. Vis fabricatrix and medicatrix of nature._ 8. _The changes of animals before and after nativity. Similarity of their structure. Changes in them from lust, hunger, and danger. All warm-blooded animals derived from one living filament. Cold-blooded animals, insects, worms, vegetables, derived also from one living filament. Male animals have teats. Male pigeon gives milk. The world itself generated. The cause of causes. A state of probation and responsibility._ V. 1. _Efficient cause of the colours of birds eggs, and of hair and feathers, which become white in snowy countries. Imagination of the female colours the egg. Ideas or motions of the retina imitated by the extremities of the nerves of touch, or rete mucosum._ 2. _Nutriment supplied by the female of three kinds. Her imagination can only affect the first kind. Mules how produced, and mulattoes. Organs of reproduction why deficient in mules. Eggs with double yolks._ VI. 1. _Various secretions produced by the extremities of the vessels, as in the glands. Contagious matter. Many glands affected by pleasurable ideas, as those which secrete the semen._ 2. _Snails and worms are hermaphrodite, yet cannot impregnate themselves. Final cause of this._ 3. _The imagination of the male forms the sex. Ideas, or motions of the nerves of vision or of touch, are imitated by the ultimate extremities of the glands of the testes, which mark the sex. This effect of the imagination belongs only to the male. The sex of the embryon is not owing to accident._ 4. _Causes of the changes in animals from imagination as in monsters. From the male. From the female._ 5. _Miscarriages from fear._ 6. _Power of the imagination of the male over the colour, form, and sex of the progeny. An instance of._ 7. _Act of generation accompanied with ideas of the male or female form. Art of begetting beautiful children of either sex._ VII. _Recapitulation._ VIII. _Conclusion. Of cause and effect. The atomic philosophy leads to a first cause._ I. The ingenious Dr. Hartley in his work on man, and some other philosophers, have been of opinion, that our immortal part acquires during this life certain habits of action or of sentiment, which become for ever indissoluble, continuing after death in a future state of existence; and add, that if these habits are of the malevolent kind, they must render the possessor miserable even in heaven. I would apply this ingenious idea to the generation or production of the embryon, or new animal, which partakes so much of the form and propensities of the parent. Owing to the imperfection of language the offspring is termed a _new_ animal, but is in truth a branch or elongation of the parent; since a part of the embryon-animal is, or was, a part of the parent; and therefore in strict language it cannot be said to be entirely _new_ at the time of its production; and therefore it may retain some of the habits of the parent-system. At the earliest period of its existence the embryon, as secreted from the blood of the male, would seem to consist of a living filament with certain capabilities of irritation, sensation, volition, and association; and also with some acquired habits or propensities peculiar to the parent: the former of these are in common with other animals; the latter seem to distinguish or produce the kind of animal, whether man or quadruped, with the similarity of feature or form to the parent. It is difficult to be conceived, that a living entity can be separated or produced from the blood by the action of a gland; and which shall afterwards become an animal similar to that in whose vessels it is formed; even though we should suppose with some modern theorists, that the blood is alive; yet every other hypothesis concerning generation rests on principles still more difficult to our comprehension. At the time of procreation this speck of entity is received into an appropriated nidus, in which it must acquire two circumstances necessary to its life and growth; one of these is food or sustenance, which is to be received by the absorbent mouths of its vessels; and the other is that part of atmospherical air, or of water, which by the new chemistry is termed oxygene, and which affects the blood by passing through the coats of the vessels which contain it. The fluid surrounding the embryon in its new habitation, which is called liquor amnii, supplies it with nourishment; and as some air cannot but be introduced into the uterus along with a new embryon, it would seem that this same fluid would for a short time, suppose for a few hours, supply likewise a sufficient quantity of the oxygene for its immediate existence. On this account the vegetable impregnation of aquatic plants is performed in the air; and it is probable that the honey-cup or nectary of vegetables requires to be open to the air, that the anthers and stigmas of the flower may have food of a more oxygenated kind than the common vegetable sap-juice. On the introduction of this primordium of entity into the uterus the irritation of the liquor amnii, which surrounds it, excites the absorbent mouths of the new vessels into action; they drink up a part of it, and a pleasurable sensation accompanies this new action; at the same time the chemical affinity of the oxygene acts through the vessels of the rubescent blood; and a previous want, or disagreeable sensation, is relieved by this process. As the want of this oxygenation of the blood is perpetual, (as appears from the incessant necessity of breathing by lungs or gills,) the vessels become extended by the efforts of pain or desire to seek this necessary object of oxygenation, and to remove the disagreeable sensation, which that want occasions. At the same time new particles of matter are absorbed, or applied to these extended vessels, and they become permanently elongated, as the fluid in contact with them soon loses the oxygenous part, which it at first possessed, which was owing to the introduction of air along with the embryon. These new blood-vessels approach the sides of the uterus, and penetrate with their fine terminations into the vessels of the mother; or adhere to them, acquiring oxygene through their coats from the passing currents of the arterial blood of the mother. See Sect. XXXVIII. 2. This attachment of the placental vessels to the internal side of the uterus by their own proper efforts appears further illustrated by the many instances of extra-uterine fetuses, which have thus attached or inserted their vessels into the peritoneum; or on the viscera, exactly in the same manner as they naturally insert or attach them to the uterus. The absorbent vessels of the embryon continue to drink up nourishment from the fluid in which they swim, or liquor amnii; and which at first needs no previous digestive preparation; but which, when the whole apparatus of digestion becomes complete, is swallowed by the mouth into the stomach, and being mixed with saliva, gastric juice, bile, pancreatic juice, and mucus of the intestines, becomes digested, and leaves a recrement, which produces the first feces of the infant, called meconium. The liquor amnii is secreted into the uterus, as the fetus requires it, and may probably be produced by the irritation of the fetus as an extraneous body; since a similar fluid is acquired from the peritoneum in cases of extra-uterine gestation. The young caterpillars of the gadfly placed in the skins of cows, and the young of the ichneumon-fly placed in the backs of the caterpillars on cabbages, seem to produce their nourishment by their irritating the sides of their nidus. A vegetable secretion and concretion is thus produced on oak-leaves by the gall-insect, and by the cynips in the bedeguar of the rose; and by the young grasshopper on many plants, by which the animal surrounds itself with froth. But in no circumstance is extra-uterine gestation so exactly resembled as by the eggs of a fly, which are deposited in the frontal sinus of sheep and calves. These eggs float in some ounces of fluid collected in a thin pellicle or hydatide. This bag of fluid compresses the optic nerve on one side, by which the vision being less distinct in that eye, the animal turns in perpetual circles towards the side affected, in order to get a more accurate view of objects; for the same reason as in squinting the affected eye is turned away from the object contemplated. Sheep in the warm months keep their noses close to the ground to prevent this fly from so readily getting into their nostrils. The liquor amnii is secreted into the womb as it is required, not only in respect to quantity, but, as the digestive powers of the fetus become formed, this fluid becomes of a different consistence and quality, till it is exchanged for milk after nativity. Haller. Physiol. V. 1. In the egg the white part, which is analogous to the liquor amnii of quadrupeds, consists of two distinct parts; one of which is more viscid, and probably more difficult of digestion, and more nutritive than the other; and this latter is used in the last week of incubation. The yolk of the egg is a still stronger or more nutritive fluid, which is drawn up into the bowels of the chick just at its exclusion from the shell, and serves it for nourishment for a day or two, till it is able to digest, and has learnt to choose the harder seeds or grains, which are to afford it sustenance. Nothing analogous to this yolk is found in the fetus of lactiferous animals, as the milk is another nutritive fluid ready prepared for the young progeny. The yolk therefore is not necessary to the spawn of fish, the eggs of insects, or for the seeds of vegetables; as their embryons have probably their food presented to them as soon as they are excluded from their shells, or have extended their roots. Whence it happens that some insects produce a living progeny in the spring and summer, and eggs in the autumn; and some vegetables have living roots or buds produced in the place of seeds, as the polygonum viviparum, and magical onions. See Botanic Garden, p. 11. art. anthoxanthum. There seems however to be a reservoir of nutriment prepared for some seeds besides their cotyledons or seed-leaves, which may be supposed in some measure analogous to the yolk of the egg. Such are the saccharine juices of apples, grapes and other fruits, which supply nutrition to the seeds after they fall on the ground. And such is the milky juice in the centre of the cocoa-nut, and part of the kernel of it; the same I suppose of all other monocotyledon seeds, as of the palms, grasses, and lilies. II. 1. The process of generation is still involved in impenetrable obscurity, conjectures may nevertheless be formed concerning some of its circumstances. First, the eggs of fish and frogs are impregnated, after they leave the body of the female; because they are deposited in a fluid, and are not therefore covered with a hard shell. It is however remarkable, that neither frogs nor fish will part with their spawn without the presence of the male; on which account female carp and gold-fish in small ponds, where there are no males, frequently die from the distention of their growing spawn. 2. The eggs of fowls, which are laid without being impregnated, are seen to contain only the yolk and white, which are evidently the food or sustenance for the future chick. 3. As the cicatricula of these eggs is given by the cock, and is evidently the rudiment of the new animal; we may conclude, that the embryon is produced by the male, and the proper food and nidus by the female. For if the female be supposed to form an equal part of the embryon, why should she form the whole of the apparatus for nutriment and for oxygenation? the male in many animals is larger, stronger, and digests more food than the female, and therefore should contribute as much or more towards the reproduction of the species; but if he contributes only half the embryon and none of the apparatus for sustenance and oxygenation, the division is unequal; the strength of the male, and his consumption of food are too great for the effect, compared with that of the female, which is contrary to the usual course of nature. In objection to this theory of generation it may be said, if the animalcula in femine, as seen by the microscope, be all of them rudiments of homunculi, when but one of them can find a nidus, what a waste nature has made of her productions? I do not assert that these moving particles, visible by the microscope, are homunciones; perhaps they may be the creatures of stagnation or putridity, or perhaps no creatures at all; but if they are supposed to be rudiments of homunculi, or embryons, such a profusion of them corresponds with the general efforts of nature to provide for the continuance of her species of animals. Every individual tree produces innumerable seeds, and every individual fish innumerable spawn, in such inconceivable abundance as would in a short space of time crowd the earth and ocean with inhabitants; and these are much more perfect animals than the animalcula in femine can be supposed to be, and perish in uncounted millions. This argument only shews, that the productions of nature are governed by general laws; and that by a wise superfluity of provision she has ensured their continuance. 2. That the embryon is secreted or produced by the male, and not by the conjunction of fluids from both male and female, appears from the analogy of vegetable seeds. In the large flowers, as the tulip, there is no similarity of apparatus between the anthers and the stigma: the seed is produced according to the observations of Spallanzani long before the flowers open, and in consequence long before it can be impregnated, like the egg in the pullet. And after the prolific dust is shed on the stigma, the seed becomes coagulated in one point first, like the cicatricula of the impregnated egg. See Botanic Garden, Part I. additional note 38. Now in these simple products of nature, if the female contributed to produce the new embryon equally with the male, there would probably have been some visible similarity of parts for this purpose, besides those necessary for the nidus and sustenance of the new progeny. Besides in many flowers the males are more numerous than the females, or than the separate uterine cells in their germs, which would shew, that the office of the male was at least as important as that of the female; whereas if the female, besides producing the egg or seed, was to produce an equal part of the embryon, the office of reproduction would be unequally divided between them. Add to this, that in the most simple kind of vegetable reproduction, I mean the buds of trees, which are their viviparous offspring, the leaf is evidently the parent of the bud, which rises in its bosom, according to the observation of Linnaeus. This leaf consists of absorbent vessels, and pulmonary ones, to obtain its nutriment, and to impregnate it with oxygene. This simple piece of living organization is also furnished with a power of reproduction; and as the new offspring is thus supported adhering to its father, it needs no mother to supply it with a nidus, and nutriment, and oxygenation; and hence no female leaf has existence. I conceive that the vessels between the bud and the leaf communicate or inosculate; and that the bud is thus served with vegetable blood, that is, with both nutriment and oxygenation, till the death of the parent-leaf in autumn. And in this respect it differs from the fetus of viviparous animals. Secondly, that then the bark-vessels belonging to the dead-leaf, and in which I suppose a kind of manna to have been deposited, become now the placental vessels, if they may be so called, of the new bud. From the vernal sap thus produced of one sugar-maple-tree in New-York and in Pennsylvania, five or six pounds of good sugar may be made annually without destroying the tree. Account of maple-sugar by B. Rushes. London, Phillips. (See Botanic Garden, Part I. additional note on vegetable placentation.) These vessels, when the warmth of the vernal sun hatches the young bud, serve it with a saccharine nutriment, till it acquires leaves of its own, and shoots a new system of absorbents down the bark and root of the tree, just as the farinaceous or oily matter in seeds, and the saccharine matter in fruits, serve their embryons with nutriment, till they acquire leaves and roots. This analogy is as forceable in so obscure a subject, as it is curious, and may in large buds, as of the horse-chesnut, be almost seen by the naked eye; if with a penknife the remaining rudiment of the last year's leaf, and of the new bud in its bosom, be cut away slice by slice. The seven ribs of the last year's leaf will be seen to have arisen from the pith in seven distinct points making a curve; and the new bud to have been produced in their centre, and to have pierced the alburnum and cortex, and grown without the assistance of a mother. A similar process may be seen on dissecting a tulip-root in winter; the leaves, which inclosed the last year's flower-stalk, were not necessary for the flower; but each of these was the father of a new bud, which may be now found at its base; and which, as it adheres to the parent, required no mother. This paternal offspring of vegetables, I mean their buds and bulbs, is attended with a very curious circumstance; and that is, that they exactly resemble their parents, as is observable in grafting fruit-trees, and in propagating flower-roots; whereas the seminal offspring of plants, being supplied with nutriment by the mother, is liable to perpetual variation. Thus also in the vegetable class dioicia, where the male flowers are produced on one tree, and the female ones on another; the buds of the male trees uniformly produce either male flowers, or other buds similar to themselves; and the buds of the female trees produce either female flowers, or other buds similar to themselves; whereas the seeds of these trees produce either male or female plants. From this analogy of the production of vegetable buds without a mother, I contend that the mother does not contribute to the formation of the living ens in animal generation, but is necessary only for supplying its nutriment and oxygenation. There is another vegetable fact published by M. Koelreuter, which he calls "a complete metamorphosis of one natural species of plants into another," which shews, that in seeds as well as in buds, the embryon proceeds from the male parent, though the form of the subsequent mature plant is in part dependant on the female. M. Koelreuter impregnated a stigma of the nicotiana rustica with the farina of the nicotiana paniculata, and obtained prolific seeds from it. With the plants which sprung from these seeds, he repeated the experiment, impregnating them with the farina of the nicotiana paniculata. As the mule plants which he thus produced were prolific, he continued to impregnate them for many generations with the farina of the nicotiana paniculata, and they became more and more like the male parent, till he at length obtained six plants in every respect perfectly similar to the nicotiana paniculata; and in no respect resembling their female parent the nicotiana rustica. _Blumenbach_ on Generation. 3. It is probable that the insects, which are said to require but one impregnation for six generations, as the aphis (see Amenit. Academ.) produce their progeny in the manner above described, that is, without a mother, and not without a father; and thus experience a lucina sine concubitu. Those who have attended to the habits of the polypus, which is found in the stagnant water of our ditches in July, affirm, that the young ones branch out from the side of the parent like the buds of trees, and after a time separate themselves from them. This is so analogous to the manner in which the buds of trees appear to be produced, that these polypi may be considered as all male animals, producing embryons, which require no mother to supply them with a nidus, or with nutriment, and oxygenation. This lateral or lineal generation of plants, not only obtains in the buds of trees, which continue to adhere to them, but is beautifully seen in the wires of knot-grass, polygonum aviculare, and in those of strawberries, fragaria vesca. In these an elongated creeping bud is protruded, and, where it touches the ground, takes root, and produces a new plant derived from its father, from which it acquires both nutriment and oxygenation; and in consequence needs no maternal apparatus for these purposes. In viviparous flowers, as those of allium magicum, and polygonum viviparum, the anthers and the stigmas become effete and perish; and the lateral or paternal offspring succeeds instead of seeds, which adhere till they are sufficiently mature, and then fall upon the ground, and take root like other bulbs. The lateral production of plants by wires, while each new plant is thus chained to its parent, and continues to put forth another and another, as the wire creeps onward on the ground, is exactly resembled by the tape-worm, or tænia, so often found in the bowels, stretching itself in a chain quite from the stomach to the rectum. Linnæus asserts, "that it grows old at one extremity, while it continues to generate young ones at the other, proceeding ad infinitum, like a root of grass. The separate joints are called gourd-worms, and propagate new joints like the parent without end, each joint being furnished with its proper mouth, and organs of digestion." Systema naturæ. Vermes tenia. In this animal there evidently appears a power of reproduction without any maternal apparatus for the purpose of supplying nutriment and oxygenation to the embryon, as it remains attached to its father till its maturity. The volvox globator, which is a transparent animal, is said by Linnæus to bear within it sons and grand-sons to the fifth generation. These are probably living fetuses, produced by the father, of different degrees of maturity, to be detruded at different periods of time, like the unimpregnated eggs of various sizes, which are found in poultry; and as they are produced without any known copulation, contribute to evince, that the living embryon in other orders of animals is formed by the male-parent, and not by the mother, as one parent has the power to produce it. This idea of the reproduction of animals from a single living filament of their fathers, appears to have been shadowed or allegorized in the curious account in sacred writ of the formation of Eve from a rib of Adam. From all these analogies I conclude, that the embryon is produced solely by the male, and that the female supplies it with a proper nidus, with sustenance, and with oxygenation; and that the idea of the semen of the male constituting only a stimulus to the egg of the female, exciting it into life, (as held by some philosophers) has no support from experiment or analogy. III. 1. Many ingenious philosophers have found so great difficulty in conceiving the manner of the reproduction of animals, that they have supposed all the numerous progeny, to have existed in miniature in the animal originally created; and that these infinitely minute forms are only evolved or distended, as the embryon increases in the womb. This idea, besides its being unsupported by any analogy we are acquainted with, ascribes a greater tenuity to organized matter, than we can readily admit; as these included embryons are supposed each of them to consist of the various and complicate parts of animal bodies: they must possess a much greater degree of minuteness, than that which was ascribed to the devils that tempted St. Anthony; of whom 20,000 were said to have been able to dance a saraband on the point of the finest needle without incommoding each other. 2. Others have supposed, that all the parts of the embryon are formed in the male, previous to its being deposited in the egg or uterus; and that it is then only to have its parts evolved or distended as mentioned above; but this is only to get rid of one difficulty by proposing another equally incomprehensible: they found it difficult to conceive, how the embryon could be formed in the uterus or egg, and therefore wished it to be formed before it came thither. In answer to both these doctrines it may be observed, 1st, that some animals, as the crab-fish, can reproduce a whole limb, as a leg which has been broken off; others, as worms and snails, can reproduce a head, or a tail, when either of them has been cut away; and that hence in these animals at least a part can be formed anew, which cannot be supposed to have existed previously in miniature. Secondly, there are new parts or new vessels produced in many diseases, as on the cornea of the eye in ophthalmy, in wens and cancers, which cannot be supposed to have had a prototype or original miniature in the embryon. Thirdly, how could mule-animals be produced, which partake of the forms of both the parents, if the original embryon was a miniature existing in the semen of the male parent? if an embryon of the male ass was only expanded, no resemblance to the mare could exist in the mule. This mistaken idea of the extension of parts seems to have had its rise from the mature man resembling the general form of the fetus; and from thence it was believed, that the parts of the fetus were distended into the man; whereas they have increased 100 times in weight, as well as 100 times in size; now no one will call the additional 99 parts a distention of the original one part in respect to weight. Thus the uterus during pregnancy is greatly enlarged in thickness and solidity as well as in capacity, and hence must have acquired this additional size by accretion of new parts, not by an extension of the old ones; the familiar act of blowing up the bladder of an animal recently slaughtered has led our imaginations to apply this idea of distention to the increase of size from natural growth; which however must be owing to the apposition of new parts; as it is evinced from the increase of weight along with the increase of dimension; and is even visible to our eyes in the elongation of our hair from the colour of its ends; or when it has been dyed on the head; and in the growth of our nails from the specks sometimes observable on them; and in the increase of the white crescent at their roots, and in the growth of new flesh in wounds, which consists of new nerves as well as of new blood-vessels. 3. Lastly, Mr. Buffon has with great ingenuity imagined the existence of certain organic particles, which are supposed to be partly alive, and partly mechanic springs. The latter of these were discovered by Mr. Needham in the milt or male organ of a species of cuttle fish, called calmar; the former, or living animalcula, are found in both male and female secretions, in the infusions of seeds, as of pepper, in the jelly of roasted veal, and in all other animal and vegetable substances. These organic particles he supposes to exist in the spermatic fluids of both sexes, and that they are derived thither from every part of the body, and must therefore resemble, as he supposes, the parts from whence they are derived. These organic particles he believes to be in constant activity, till they become mixed in the womb, and then they instantly join and produce an embryon or fetus similar to the two parents. Many objections might be adduced to this fanciful theory, I shall only mention two. First, that it is analogous to no known animal laws. And secondly, that as these fluids, replete with organic particles derived both from the male and female organs, are supposed to be similar; there is no reason why the mother should not produce a female embryon without the assistance of the male, and realize the lucina sine concubitu. IV. 1. I conceive the primordium, or rudiment of the embryon, as secreted from the blood of the parent, to consist of a simple living filament as a muscular fibre; which I suppose to be an extremity of a nerve of loco-motion, as a fibre of the retina is an extremity of a nerve of sensation; as for instance one of the fibrils, which compose the mouth of an absorbent vessel; I suppose this living filament, of whatever form it may be, whether sphere, cube, or cylinder, to be endued with the capability of being excited into action by certain kinds of stimulus. By the stimulus of the surrounding fluid, in which it is received from the male, it may bend into a ring; and thus form the beginning of a tube. Such moving filaments, and such rings, are described by those, who have attended to microscopic animalcula. This living ring may now embrace or absorb a nutritive particle of the fluid, in which it swims; and by drawing it into its pores, or joining it by compression to its extremities, may increase its own length or crassitude; and by degrees the living ring may become a living tube. 2. With this new organization, or accretion of parts, new kinds of irritability may commence; for so long as there was but one living organ, it could only be supposed to possess irritability; since sensibility may be conceived to be an extension of the effect of irritability over the rest of the system. These new kinds of irritability and of sensibility in consequence of new organization, appear from variety of facts in the more mature animal; thus the formation of the testes, and consequent secretion of the semen, occasion the passion of lust; the lungs must be previously formed before their exertions to obtain fresh air can exist; the throat or oesophagus must be formed previous to the sensation or appetites of hunger and thirst; one of which seems to reside at the upper end, and the other at the lower end of that canal. Thus also the glans penis, when it is distended with blood, acquires a new sensibility, and a new appetency. The same occurs to the nipples of the breasts of female animals, when they are distended with blood, they acquire the new appetency of giving milk. So inflamed tendons and membranes, and even bones, acquire new sensations; and the parts of mutilated animals, as of wounded snails, and polypi, and crabs, are reproduced; and at the same time acquire sensations adapted to their situations. Thus when the head of a snail is reproduced after decollation with a sharp rasor, those curious telescopic eyes are also reproduced, and acquire their sensibility to light, as well as their adapted muscles for retraction on the approach of injury. With every new change, therefore, of organic form, or addition of organic parts, I suppose a new kind of irritability or of sensibility to be produced; such varieties of irritability or of sensibility exist in our adult state in the glands; every one of which is furnished with an irritability, or a taste, or appetency, and a consequent mode of action peculiar to itself. In this manner I conceive the vessels of the jaws to produce those of the teeth, those of the fingers to produce the nails, those of the skin to produce the hair; in the same manner as afterwards about the age of puberty the beard and other great changes in the form of the body, and disposition of the mind, are produced in consequence of the new secretion of semen; for if the animal is deprived of this secretion those changes do not take place. These changes I conceive to be formed not by elongation or distention of primeval stamina, but by apposition of parts; as the mature crab-fish, when deprived of a limb, in a certain space of time has power to regenerate it; and the tadpole puts forth its feet long after its exclusion from the spawn; and the caterpillar in changing into a butterfly acquires a new form, with new powers, new sensations, and new desires. The natural history of butterflies, and moths, and beetles, and gnats, is full of curiosity; some of them pass many months, and others even years, in their caterpillar or grub state; they then rest many weeks without food, suspended in the air, buried in the earth, or submersed in water; and change themselves during this time into an animal apparently of a different nature; the stomachs of some of them, which before digested vegetable leaves or roots, now only digest honey; they have acquired wings for the purpose of seeking this new food, and a long proboscis to collect it from flowers, and I suppose a sense of smell to detect the secret places in flowers, where it is formed. The moths, which fly by night, have a much longer proboscis rolled up under their chins like a watch spring; which they extend to collect the honey from flowers in their sleeping state; when they are closed, and the nectaries in consequence more difficult to be plundered. The beetle kind are furnished with an external covering of a hard material to their wings, that they may occasionally again make holes in the earth, in which they passed the former state of their existence. But what most of all distinguishes these new animals is, that they are new furnished with the powers of reproduction; and that they now differ from each other in sex, which does not appear in their caterpillar or grub state. In some of them the change from a caterpillar into a butterfly or moth seems to be accomplished for the sole purpose of their propagation; since they immediately die after this is finished, and take no food in the interim, as the silk-worm in this climate; though it is possible, it might take honey as food, if it was presented to it. For in general it would seem, that food of a more stimulating kind, the honey of vegetables instead of their leaves, was necessary for the purpose of the seminal reproduction of these animals, exactly similar to what happens in vegetables; in these the juices of the earth are sufficient for their purpose of reproduction by buds or bulbs; in which the new plant seems to be formed by irritative motions, like the growth of their other parts, as their leaves or roots; but for the purpose of seminal or amatorial reproduction, where sensation is required, a more stimulating food becomes necessary for the anther, and stigma; and this food is honey; as explained in Sect. XIII. on Vegetable Animation. The gnat and the tadpole resemble each other in their change from natant animals with gills into aerial animals with lungs; and in their change of the element in which they live; and probably of the food, with which they are supported; and lastly, with their acquiring in their new state the difference of sex, and the organs of seminal or amatorial reproduction. While the polypus, who is their companion in their former state of life, not being allowed to change his form and element, can only propagate like vegetable buds by the same kind of irritative motions, which produces the growth of his own body, without the seminal or amatorial propagation, which requires sensation; and which in gnats and tadpoles seems to require a change both of food and of respiration. From hence I conclude, that with the acquisition of new parts, new sensations, and new desires, as well as new powers, are produced; and this by accretion to the old ones, and not by distention of them. And finally, that the most essential parts of the system, as the brain for the purpose of distributing the power of life, and the placenta for the purpose of oxygenating the blood, and the additional absorbent vessels for the purpose of acquiring aliment, are first formed by the irritations above mentioned, and by the pleasurable sensations attending those irritations, and by the exertions in consequence of painful sensations, similar to those of hunger and suffocation. After these an apparatus of limbs for future uses, or for the purpose of moving the body in its present natant state, and of lungs for future respiration, and of testes for future reproduction, are formed by the irritations and sensations, and consequent exertions of the parts previously existing, and to which the new parts are to be attached. 3. In confirmation of these ideas it may be observed, that all the parts of the body endeavour to grow, or to make additional parts to themselves throughout our lives; but are restrained by the parts immediately containing them; thus, if the skin be taken away, the fleshy parts beneath soon shoot out new granulations, called by the vulgar proud flesh. If the periosteum be removed, a similar growth commences from the bone. Now in the case of the imperfect embryon, the containing or confining parts are not yet supposed to be formed, and hence there is nothing to restrain its growth. 4. By the parts of the embryon being thus produced by new apportions, many phenomena both of animal and vegetable productions receive an easier explanation; such as that many fetuses are deficient at the extremities, as in a finger or a toe, or in the end of the tongue, or in what is called a hare-lip with deficiency of the palate. For if there should be a deficiency in the quantity of the first nutritive particles laid up in the egg for the reception of the first living filament, the extreme parts, as being last formed, must shew this deficiency by their being imperfect. This idea of the growth of the embryon accords also with the production of some monstrous births, which consist of a duplicature of the limbs, as chickens with four legs; which could not occur, if the fetus was formed by the distention of an original stamen, or miniature. For if there should be a superfluity of the first nutritive particles laid up in the egg for the first living filament; it is easy to conceive, that a duplicature of some parts may be formed. And that such superfluous nourishment sometimes exists, is evinced by the double yolks in some eggs, which I suppose were thus formed previous to their impregnation by the exuberant nutriment of the hen. This idea is confirmed by the analogy of the monsters in the vegetable world also; in which a duplicate or triplicate production of various parts of the flower is observable, as a triple nectary in some columbines, and a triple petal in some primroses; and which are supposed to be produced by abundant nourishment. 5. If the embryon be received into a fluid, whose stimulus is different in some degree from the natural, as in the production of mule-animals, the new irritabilities or sensibilities acquired by the increasing or growing organized parts may differ, and thence produce parts not similar to the father, but of a kind belonging in part to the mother; and thus, though the original stamen or living ens was derived totally from the father, yet new irritabilities or sensibilities being excited, a change of form corresponding with them will be produced. Nor could the production of mules exist, if the stamen or miniature of all the parts of the embryon is previously formed in the male semen, and is only distended by nourishment in the female uterus. Whereas this difficulty ceases, if the embryon be supposed to consist of a living filament, which acquires or makes new parts with new irritabilities, as it advances in its growth. The form, solidity, and colour, of the particles of nutriment laid up for the reception of the first living filament, as well as their peculiar kind of stimulus, may contribute to produce a difference in the form, solidity, and colour of the fetus, so as to resemble the mother, as it advances in life. This also may especially happen during the first state of the existence of the embryon, before it has acquired organs, which can change these first nutritive particles, as explained in No. 5. 2. of this Section. And as these nutritive particles are supposed to be similar to those, which are formed for her own nutrition, it follows that the fetus should so far resemble the mother. This explains, why hereditary diseases may be derived either from the male or female parent, as well as the peculiar form of either of their bodies. Some of these hereditary diseases are simply owing to a deficient activity of a part of the system, as of the absorbent vessels, which open into the cells or cavities of the body, and thus occasion dropsies. Others are at the same time owing to an increase of sensation, as in scrophula and consumption; in these the obstruction of the fluids is first caused by the inirritability of the vessels, and the inflammation and ulcers which succeed, are caused by the consequent increase of sensation in the obstructed part. Other hereditary diseases, as the epilepsy, and other convulsions, consist in too great voluntary exertions in consequence of disagreeable sensation in some particular diseased part. Now as the pains, which occasion these convulsions, are owing to defect of the action of the diseased part, as shewn in Sect. XXXIV. it is plain, that all these hereditary diseases may have their origin either from defective irritability derived from the father, or from deficiency of the stimulus of the nutriment derived from the mother. In either case the effect would be similar; as a scrophulous race is frequently produced among the poor from the deficient stimulus of bad diet, or of hunger; and among the rich, by a deficient irritability from their having been long accustomed to too great stimulus, as of vinous spirit. 6. From this account of reproduction it appears, that all animals have a similar origin, viz. from a single living filament; and that the difference of their forms and qualities has arisen only from the different irritabilities and sensibilities, or voluntarities, or associabilities, of this original living filament; and perhaps in some degree from the different forms of the particles of the fluids, by which it has been at first stimulated into activity. And that from hence, as Linnæus has conjectured in respect to the vegetable world, it is not impossible, but the great variety of species of animals, which now tenant the earth, may have had their origin from the mixture of a few natural orders. And that those animal and vegetable mules, which could continue their species, have done so, and constitute the numerous families of animals and vegetables which now exist; and that those mules, which were produced with imperfect organs of generation, perished without reproduction, according to the observation of Aristotle; and are the animals, which we now call mules. See Botanic Garden, Part II. Note on Dianthus. Such a promiscuous intercourse of animals is said to exist at this day in New South Wales by Captain Hunter. And that not only amongst the quadrupeds and birds of different kinds, but even amongst the fish, and, as he believes, amongst the vegetables. He speaks of an animal between the opossum and the kangaroo, from the size of a sheep to that of a rat. Many fish seemed to partake of the shark; some with a shark's head and shoulders, and the hind part of a shark; others with a shark's head and the body of a mullet; and some with a shark's head and the flat body of a sting-ray. Many birds partake of the parrot; some have the head, neck, and bill of a parrot, with long straight feet and legs; others with legs and feet of a parrot, with head and neck of a sea gull. Voyage to South Wales by Captain John Hunter, p. 68. 7. All animals therefore, I contend, have a similar cause of their organization, originating from a single living filament, endued indeed with different kinds of irritabilities and sensibilities, or of animal appetencies; which exist in every gland, and in every moving organ of the body, and are as essential to living organization as chemical affinities are to certain combinations of inanimate matter. If I might be indulged to make a simile in a philosophical work, I should say, that the animal appetencies are not only perhaps less numerous originally than the chemical affinities; but that like these latter, they change with every new combination; thus vital air and azote, when combined, produce nitrous acid; which now acquires the property of dissolving silver; so with every new additional part to the embryon, as of the throat or lungs, I suppose a new animal appetency to be produced. In this early formation of the embryon from the irritabilities, sensibilities, and associabilities, and consequent appetencies, the faculty of volition can scarcely be supposed to have had its birth. For about what can the fetus deliberate, when it has no choice of objects? But in the more advanced state of the fetus, it evidently possesses volition; as it frequently changes its attitude, though it seems to sleep the greatest part of its time; and afterwards the power of volition contributes to change or alter many parts of the body during its growth to manhood, by our early modes of exertion in the various departments of life. All these faculties then constitute the vis fabricatrix, and the vis conservatrix, as well as the vis medicatrix of nature, so much spoken of, but so little understood by philosophers. 8. When we revolve in our minds, first, the great changes, which we see naturally produced in animals after their nativity, as in the production of the butterfly with painted wings from the crawling caterpillar; or of the respiring frog from the subnatant tadpole; from the feminine boy to the bearded man, and from the infant girl to the lactescent woman; both which changes may be prevented by certain mutilations of the glands necessary to reproduction. Secondly, when we think over the great changes introduced into various animals by artificial or accidental cultivation, as in horses, which we have exercised for the different purposes of strength or swiftness, in carrying burthens or in running races; or in dogs, which have been cultivated for strength and courage, as the bull-dog; or for acuteness of his sense or smell, as the hound and spaniel; or for the swiftness of his foot, as the greyhound; or for his swimming in the water, or for drawing snow-sledges, as the rough-haired dogs of the north; or lastly, as a play-dog for children, as the lap-dog; with the changes of the forms of the cattle, which have been domesticated from the greatest antiquity, as camels, and sheep; which have undergone so total a transformation, that we are now ignorant from what species of wild animals they had their origin. Add to these the great changes of shape and colour, which we daily see produced in smaller animals from our domestication of them, as rabbits, or pigeons; or from the difference of climates and even of seasons; thus the sheep of warm climates are covered with hair instead of wool; and the hares and partridges of the latitudes, which are long buried in snow, become white during the winter months; add to these the various changes produced in the forms of mankind, by their early modes of exertion; or by the diseases occasioned by their habits of life; both of which became hereditary, and that through many generations. Those who labour at the anvil, the oar, or the loom, as well as those who carry sedan-chairs, or who have been educated to dance upon the rope, are distinguishable by the shape of their limbs; and the diseases occasioned by intoxication deform the countenance with leprous eruptions, or the body with tumid viscera, or the joints with knots and distortions. Thirdly, when we enumerate the great changes produced in the species of animals before their nativity; these are such as resemble the form or colour of their parents, which have been altered by the cultivation or accidents above related, and are thus continued to their posterity. Or they are changes produced by the mixture of species as in mules; or changes produced probably by the exuberance of nourishment supplied to the fetus, as in monstrous births with additional limbs; many of these enormities of shape are propagated, and continued as a variety at least, if not as a new species of animal. I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw, and with wings to their feet; and of others without rumps. Mr. Buffon mentions a breed of dogs without tails, which are common at Rome and at Naples, which he supposes to have been produced by a custom long established of cutting their tails close off. There are many kinds of pigeons, admired for their peculiarities, which are monsters thus produced and propagated. And to these must be added, the changes produced by the imagination of the male parent, as will be treated of more at large in No. VI. of this Section. When we consider all these changes of animal form, and innumerable others, which may be collected from the books of natural history; we cannot but be convinced, that the fetus or embryon is formed by apposition of new parts, and not by the distention of a primordial nest of germs, included one within another, like the cups of a conjurer. Fourthly, when we revolve in our minds the great similarity of structure, which obtains in all the warm-blooded animals, as well quadrupeds, birds, and amphibious animals, as in mankind; from the mouse and bat to the elephant and whale; one is led to conclude, that they have alike been produced from a similar living filament. In some this filament in its advance to maturity has acquired hands and fingers, with a fine sense of touch, as in mankind. In others it has acquired claws or talons, as in tygers and eagles. In others, toes with an intervening web, or membrane, as in seals and geese. In others it has acquired cloven hoofs, as in cows and swine; and whole hoofs in others, as in the horse. While in the bird kind this original living filament has put forth wings instead of arms or legs, and feathers instead of hair. In some it has protruded horns on the forehead instead of teeth in the fore part of the upper jaw; in others tushes instead of horns; and in others beaks instead of either. And all this exactly as is daily seen in the transmutations of the tadpole, which acquires legs and lungs, when he wants them; and loses his tail, when it is no longer of service to him. Fifthly, from their first rudiment, or primordium, to the termination of their lives, all animals undergo perpetual transformations; which are in part produced by their own exertions in consequence of their desires and aversions, of their pleasures and their pains, or of irritations, or of associations; and many of these acquired forms or propensities are transmitted to their posterity. See Sect. XXXI. 1. As air and water are supplied to animals in sufficient profusion, the three great objects of desire, which have changed the forms of many animals by their exertions to gratify them, are those of lust, hunger, and security. A great want of one part of the animal world has consisted in the desire of the exclusive possession of the females; and these have acquired weapons to combat each other for this purpose, as the very thick, shield-like, horny skin on the shoulder of the boar is a defence only against animals of his own species, who strike obliquely upwards, nor are his tushes for other purposes, except to defend himself, as he is not naturally a carnivorous animal. So the horns of the stag are sharp to offend his adversary, but are branched for the purpose of parrying or receiving the thrusts of horns similar to his own, and have therefore been formed for the purpose of combating other stags for the exclusive possession of the females; who are observed, like the ladies in the times of chivalry, to attend the car of the victor. The birds, which do not carry food to their young, and do not therefore marry, are armed with spurs for the purpose of fighting for the exclusive possession of the females, as cocks and quails. It is certain that these weapons are not provided for their defence against other adversaries, because the females of these species are without this armour. The final cause of this contest amongst the males seems to be, that the strongest and most active animal should propagate the species, which should thence become improved. Another great want consists in the means of procuring food, which has diversified the forms of all species of animals. Thus the nose of the swine has become hard for the purpose of turning up the soil in search of insects and of roots. The trunk of the elephant is an elongation of the nose for the purpose of pulling down the branches of trees for his food, and for taking up water without bending his knees. Beasts of prey have acquired strong jaws or talons. Cattle have acquired a rough tongue and a rough palate to pull off the blades of grass, as cows and sheep. Some birds have acquired harder beaks to crack nuts, as the parrot. Others have acquired beaks adapted to break the harder seeds, as sparrows. Others for the softer seeds of flowers, or the buds of trees, as the finches. Other birds have acquired long beaks to penetrate the moister soils in search of insects or roots, as woodcocks; and others broad ones to filtrate the water of lakes, and to retain aquatic insects. All which seem to have been gradually produced during many generations by the perpetual endeavour of the creatures to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purposes required. The third great want amongst animals is that of security, which seems much to have diversified the forms of their bodies and the colour of them; these consist in the means of escaping other animals more powerful than themselves. Hence some animals have acquired wings instead of legs, as the smaller birds, for the purpose of escape. Others great length of fin, or of membrane, as the flying fish, and the bat. Others great swiftness of foot, as the hare. Others have acquired hard or armed shells, as the tortoise and the echinus marinus. Mr. Osbeck, a pupil of Linnæus, mentions the American frog fish, Lophius Histrio, which inhabits the large floating islands of sea-weed about the Cape of Good Hope, and has fulcra resembling leaves, that the fishes of prey may mistake it for the sea-weed, which it inhabits. Voyage to China, p. 113. The contrivances for the purposes of security extend even to vegetables, as is seen in the wonderful and various means of their concealing or defending their honey from insects, and their seeds from birds. On the other hand swiftness of wing has been acquired by hawks and swallows to pursue their prey; and a proboscis of admirable structure has been acquired by the bee, the moth, and the humming bird, for the purpose of plundering the nectaries of flowers. All which seem to have been formed by the original living filament, excited into action by the necessities of the creatures, which possess them, and on which their existence depends. From thus meditating on the great similarity of the structure of the warm-blooded animals, and at the same time of the great changes they undergo both before and after their nativity; and by considering in how minute a portion of time many of the changes of animals above described have been produced; would it be too bold to imagine, that in the great length of time, since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, would it be too bold to imagine, that all warm-blooded animals have arisen from one living filament, which THE GREAT FIRST CAUSE endued with animality, with the power of acquiring new parts, attended with new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down those improvements by generation to its posterity, world without end! Sixthly, The cold-blooded animals, as the fish-tribes, which are furnished with but one ventricle of the heart, and with gills instead of lungs, and with fins instead of feet or wings, bear a great similarity to each other; but they differ, nevertheless, so much in their general structure from the warm-blooded animals, that it may not seem probable at first view, that the same living filament could have given origin to this kingdom of animals, as to the former. Yet are there some creatures, which unite or partake of both these orders of animation, as the whales and seals; and more particularly the frog, who changes from an aquatic animal furnished with gills to an aerial one furnished with lungs. The numerous tribes of insects without wings, from the spider to the scorpion, from the flea to the lobster; or with wings, from the gnat and the ant to the wasp and the dragon-fly, differ so totally from each other, and from the red-blooded classes above described, both in the forms of their bodies, and their modes of life; besides the organ of sense, which they seem to possess in their antennæ or horns, to which it has been thought by some naturalists, that other creatures have nothing similar; that it can scarcely be supposed that this nation of animals could have been produced by the same kind of living filament, as the red-blooded classes above mentioned. And yet the changes which many of them undergo in their early state to that of their maturity, are as different, as one animal can be from another. As those of the gnat, which passes his early state in water, and then stretching out his new wings, and expanding his new lungs, rises in the air; as of the caterpillar, and bee-nymph, which feed on vegetable leaves or farina, and at length bursting from their self-formed graves, become beautiful winged inhabitants of the skies, journeying from flower to flower, and nourished by the ambrosial food of honey. There is still another class of animals, which are termed vermes by Linnæus, which are without feet, or brain, and are hermaphrodites, as worms, leeches, snails, shell-fish, coralline insects, and sponges; which possess the simplest structure of all animals, and appear totally different from those already described. The simplicity of their structure, however, can afford no argument against their having been produced from a living filament as above contended. Last of all the various tribes of vegetables are to be enumerated amongst the inferior orders of animals. Of these the anthers and stigmas have already been shewn to possess some organs of sense, to be nourished by honey, and to have the power of generation like insects, and have thence been announced amongst the animal kingdom in Sect. XIII. and to these must be added the buds and bulbs which constitute the viviparous offspring of vegetation. The former I suppose to be beholden to a single living filament for their seminal or amatorial procreation; and the latter to the same cause for their lateral or branching generation, which they possess in common with the polypus, tænia, and volvox; and the simplicity of which is an argument in favour of the similarity of its cause. Linnæus supposes, in the Introduction to his Natural Orders, that very few vegetables were at first created, and that their numbers were increased by their intermarriages, and adds, suadent hæc Creatoris leges a simplicibus ad composita. Many other changes seem to have arisen in them by their perpetual contest for light and air above ground, and for food or moisture beneath the soil. As noted in Botanic Garden, Part II. Note on Cuscuta. Other changes of vegetables from climate, or other causes, are remarked in the Note on Curcuma in the same work. From these one might be led to imagine, that each plant at first consisted of a single bulb or flower to each root, as the gentianella and daisy; and that in the contest for air and light new buds grew on the old decaying flower stem, shooting down their elongated roots to the ground, and that in process of ages tall trees were thus formed, and an individual bulb became a swarm of vegetables. Other plants, which in this contest for light and air were too slender to rise by their own strength, learned by degrees to adhere to their neighbours, either by putting forth roots like the ivy, or by tendrils like the vine, or by spiral contortions like the honeysuckle; or by growing upon them like the misleto, and taking nourishment from their barks; or by only lodging or adhering on them, and deriving nourishment from the air, as tillandsia. Shall we then say that the vegetable living filament was originally different from that of each tribe of animals above described? And that the productive living filament of each of those tribes was different originally from the other? Or, as the earth and ocean were probably peopled with vegetable productions long before the existence of animals; and many families of these animals long before other families of them, shall we conjecture that one and the same kind of living filaments is and has been the cause of all organic life? This idea of the gradual formation and improvement of the animal world accords with the observations of some modern philosophers, who have supposed that the continent of America has been raised out of the ocean at a later period of time than the other three quarters of the globe, which they deduce from the greater comparative heights of its mountains, and the consequent greater coldness of its respective climates, and from the less size and strength of its animals, as the tygers and allegators compared with those of Asia or Africa. And lastly, from the less progress in the improvements of the mind of its inhabitants in respect to voluntary exertions. This idea of the gradual formation and improvement of the animal world seems not to have been unknown to the ancient philosophers. Plato having probably observed the reciprocal generation of inferior animals, as snails and worms, was of opinion, that mankind with all other animals were originally hermaphrodites during the infancy of the world, and were in process of time separated into male and female. The breasts and teats of all male quadrupeds, to which no use can be now assigned, adds perhaps some shadow of probability to this opinion. Linnæus excepts the horse from the male quadrupeds, who have teats; which might have shewn the earlier origin of his exigence; but Mr. J. Hunter asserts, that he has discovered the vestiges of them on his sheath, and has at the same time enriched natural history with a very curious fact concerning the male pigeon; at the time of hatching the eggs both the male and female pigeon undergo a great change in their crops; which thicken and become corrugated, and secrete a kind of milky fluid, which coagulates, and with which alone they for a few days feed their young, and afterwards feed them with this coagulated fluid mixed with other food. How this resembles the breasts of female quadrupeds after the production of their young! and how extraordinary, that the male should at this time give milk as well as the female! See Botanic Garden, Part II. Note on Curcuma. The late Mr. David Hume, in his posthumous works, places the powers of generation much above those of our boasted reason; and adds, that reason can only make a machine, as a clock or a ship, but the power of generation makes the maker of the machine; and probably from having observed, that the greatest part of the earth has been formed out of organic recrements; as the immense beds of limestone, chalk, marble, from the shells of fish; and the extensive provinces of clay, sandstone, ironstone, coals, from decomposed vegetables; all which have been first produced by generation, or by the secretions of organic life; he concludes that the world itself might have been generated, rather than created; that is, it might have been gradually produced from very small beginnings, increasing by the activity of its inherent principles, rather than by a sudden evolution of the whole by the Almighty fire.--What a magnificent idea of the infinite power of THE GREAT ARCHITECT! THE CAUSE OF CAUSES! PARENT OF PARENTS! ENS ENTIUM! For if we may compare infinities, it would seem to require a greater infinity of power to cause the causes of effects, than to cause the effects themselves. This idea is analogous to the improving excellence observable in every part of the creation; such as in the progressive increase of the solid or habitable parts of the earth from water; and in the progressive increase of the wisdom and happiness of its inhabitants; and is consonant to the idea of our present situation being a state of probation, which by our exertions we may improve, and are consequently responsible for our actions. V. 1. The efficient cause of the various colours of the eggs of birds, and of the air and feathers of animals, is a subject so curious, that I shall beg to introduce it in this place. The colours of many animals seem adapted to their purposes of concealing themselves either to avoid danger, or to spring upon their prey. Thus the snake and wild cat, and leopard, are so coloured as to resemble dark leaves and their lighter interstices; birds resemble the colour of the brown ground, or the green hedges, which they frequent; and moths and butterflies are coloured like the flowers which they rob of their honey. Many instances are mentioned of this kind in Botanic Garden, p. 2. Note on Rubia. These colours have, however, in some instances another use, as the black diverging area from the eyes of the swan; which, as his eyes are placed less prominent than those of other birds, for the convenience of putting down his head under water, prevents the rays of light from being reflected into his eye, and thus dazzling his sight, both in air and beneath the water; which must have happened, if that surface had been white like the rest of his feathers. There is a still more wonderful thing concerning these colours adapted to the purpose of concealment; which is, that the eggs of birds are so coloured as to resemble the colour of the adjacent objects and their interfaces. The eggs of hedge-birds are greenish with dark spots; those of crows and magpies, which are seen from beneath through wicker nests, are white with dark spots; and those of larks and partridges are russet or brown, like their nests or situations. A thing still more astonishing is, that many animals in countries covered with snow become white in winter, and are said to change their colour again in the warmer months, as bears, hares, and partridges. Our domesticated animals lose their natural colours, and break into great variety, as horses, dogs, pigeons. The final cause of these colours is easily understood, as they serve some purposes of the animal, but the efficient cause would seem almost beyond conjecture. First, the choroid coat of the eye, on which the semitransparent retina is expanded, is of different colour in different animals; in those which feed on grass it is green; from hence there would appear some connexion between the colour of the choroid coat and of that constantly painted on the retina by the green grass. Now, when the ground becomes covered with snow, it would seem, that that action of the retina, which is called whiteness, being constantly excited in the eye, may be gradually imitated by the extremities of the nerves of touch, or rete mucosum of the skin. And if it be supposed, that the action of the retina in producing the perception of any colour consists in so disposing its own fibres or surface, as to reflect those coloured rays only, and transmit the others like soap-bubbles; then that part of the retina, which gives us the perception of snow, must at that time be white; and that which gives us the perception of grass, must be green. Then if by the laws of imitation, as explained in Section XII. 3. 3. and XXXIX. 6. the extremities of the nerves of touch in the rete mucosum be induced into similar action, the skin or feathers, or hair, may in like manner so dispose their extreme fibres, as to reflect white; for it is evident, that all these parts were originally obedient to irritative motions during their growth, and probably continue to be so; that those irritative motions are not liable in a healthy state to be succeeded by sensation; which however is no uncommon thing in their diseased state, or in their infant state, as in plica polonica, and in very young pen-feathers, which are still full of blood. It was shewn in Section XV. on the Production of Ideas, that the moving organ of sense in some circumstances resembled the object which produced that motion. Hence it may be conceived, that the rete mucosum, which is the extremity of the nerves of touch, may by imitating the motions of the retina become coloured. And thus, like the fable of the camelion, all animals may possess a tendency to be coloured somewhat like the colours they most frequently inspect, and finally, that colours may be thus given to the egg-shell by the imagination of the female parent; which shell is previously a mucous membrane, indued with irritability, without which it could not circulate its fluids, and increase in its bulk. Nor is this more wonderful than that a single idea of imagination mould in an instant colour the whole surface of the body of a bright scarlet, as in the blush of shame, though by a very different process. In this intricate subject nothing but loose analogical conjectures can be had, which may however lead to future discoveries; but certain it is that both the change of the colour of animals to white in the winters of snowy countries, and the spots on birds eggs, must have some efficient cause; since the uniformity of their production shews it cannot arise from a fortuitous concurrence of circumstances; and how is this efficient cause to be detected, or explained, but from its analogy to other animal facts? 2. The nutriment supplied by the female parent in viviparous animals to their young progeny may be divided into three kinds, corresponding with the age of the new creature. 1. The nutriment contained in the ovum as previously prepared for the embryon in the ovary. 2. The liquor amnii prepared for the fetus in the uterus, and in which it swims; and lastly, the milk prepared in the pectoral glands for the new born-child. There is reason to conclude that variety of changes may be produced in the new animal from all these sources of nutriment, but particularly from the first of them.. The organs of digestion and of sanguification in adults, and afterwards those of secretion, prepare or separate the particles proper for nourishment from other combinations of matter, or recombine them into new kinds of matter, proper to excite into action the filaments, which absorb or attract them by animal appetency. In this process we must attend not only to the action of the living filament which receives a nutritive particle to its bosom, but also to the kind of particle, in respect to form, or size, or colour, or hardness, which is thus previously prepared for it by digestion, sanguification, and secretion. Now as the first filament of entity cannot be furnished with the preparative organs above mentioned, the nutritive particles, which are at first to be received by it, are prepared by the mother; and deposited in the ovum ready for its reception. These nutritive particles must be supposed to differ in some respects, when thus prepared by different animals. They may differ in size, solidity, colour, and form; and yet may be sufficiently congenial to the living filament, to which they are applied, as to excite its activity by their stimulus, and its animal appetency to receive them, and to combine them with itself into organization. By this first nutriment thus prepared for the embryon is not meant the liquor amnii, which is produced afterwards, nor the larger exterior parts of the white of the egg; but the fluid prepared, I suppose, in the ovary of viviparous animals, and that which immediately surrounds the cicatricula of an impregnated egg, and is visible to the eye in a boiled one. Now these ultimate particles of animal matter prepared by the glands of the mother may be supposed to resemble the similar ultimate particles, which were prepared for her own nourishment; that is, to the ultimate particles of which her own organization consists. And that hence when these become combined with a new embryon, which in its early state is not furnished with stomach, or glands, to alter them; that new embryon will bear some resemblance to the mother. This seems to be the origin of the compound forms of mules, which evidently partake of both parents, but principally of the male parent. In this production of chimeras the antients seem to have indulged their fancies, whence the sphinxes, griffins, dragons, centaurs, and minotaurs, which are vanished from modern credulity. It would seem, that in these unnatural conjunctions, when the nutriment deposited by the female was so ill adapted to stimulate the living filament derived from the male into action, and to be received; or embraced by it, and combined with it into organization, as not to produce the organs necessary to life, as the brain, or heart, or stomach, that no mule was produced. Where all the parts necessary to life in these compound animals were formed sufficiently perfect, except the parts of generation, those animals were produced which are now called mules. The formation of the organs of sexual generation, in contradistinction to that by lateral buds, in vegetables, and in some animals, as the polypus, the tænia, and the volvox, seems the chef d'oeuvre, the master-piece of nature; as appears from many flying insects, as in moths and butterflies, who seem to undergo a general change of their forms solely for the purpose of sexual reproduction, and in all other animals this organ is not complete till the maturity of the creature. Whence it happens that, in the copulation of animals of different species, the parts necessary to life are frequently completely formed; but those for the purpose of generation are defective, as requiring a nicer organization; or more exact coincidence of the particles of nutriment to the irritabilities or appetencies of the original living filament. Whereas those mules, where all the parts could be perfectly formed, may have been produced in early periods of time, and may have added to the numbers of our various species of animals, as before observed. As this production of mules is a constant effect from the conjunction of different species of animals, those between the horse and the female ass always resembling the horse more than the ass; and those, on the contrary, between the male ass and the mare, always resembling the ass more than the mare; it cannot be ascribed to the imagination of the male animal which cannot be supposed to operate so uniformly; but to the form of the first nutritive particles, and to their peculiar stimulus exciting the living filament to select and combine them with itself. There is a similar uniformity of effect in respect to the colour of the progeny produced between a white man, and a black woman, which, if I am well informed, is always of the mulatto kind, or a mixture of the two; which may perhaps be imputed to the peculiar form of the particles of nutriment supplied to the embryon by the mother at the early period of its existence, and their peculiar stimulus; as this effect, like that of the mule progeny above treated of, is uniform and consistent, and cannot therefore be ascribed to the imagination of either of the parents. Dr. Thunberg observes, in his Journey to the Cape of Good Hope, that there are some families, which have descended from blacks in the female line for three generations. The first generation proceeding from an European, who married a tawny slave, remains tawny, but approaches to a white complexion; but the children of the third generation, mixed with Europeans, become quite white, and are often remarkably beautiful. V. i. p. 112. When the embryon has produced a placenta, and furnished itself with vessels for selection of nutritious particles, and for oxygenation of them, no great change in its form or colour is likely to be produced by the particles of sustenance it now takes from the fluid, in which it is immersed; because it has now acquired organs to alter or new combine them. Hence it continues to grow, whether this fluid, in which it swims, be formed by the uterus or by any other cavity of the body, as in extra-uterine gestation; and which would seem to be produced by the stimulus of the fetus on the sides of the cavity, where it is found, as mentioned before. And thirdly, there is still less reason to expect any unnatural change to happen to the child after its birth from the difference of the milk it now takes; because it has acquired a stomach, and lungs, and glands, of sufficient power to decompose and recombine the milk; and thus to prepare from it the various kinds of nutritious particles, which the appetencies of the various fibrils or nerves may require. From all this reasoning I would conclude, that though the imagination of the female may be supposed to affect the embryon by producing a difference in its early nutriment; yet that no such power can affect it after it has obtained a placenta, and other organs; which may select or change the food, which is presented to it either in the liquor amnii, or in the milk. Now as the eggs in pullets, like the seeds in vegetables, are produced gradually, long before they are impregnated, it does not appear how any sudden effect of imagination of the mother at the time of impregnation can produce any considerable change in the nutriment already thus laid up for the expected or desired embryon. And that hence any changes of the embryon, except those uniform ones in the production of mules and mulattoes, more probably depend on the imagination of the male parent. At the same time it seems manifest, that those monstrous births, which consist in some deficiencies only, or some redundancies of parts, originate from the deficiency or redundance of the first nutriment prepared in the ovary, or in the part of the egg immediately surrounding the cicatricula, as described above; and which continues some time to excite the first living filament into action, after the simple animal is completed; or ceases to excite it, before the complete form is accomplished. The former of these circumstances is evinced by the eggs with double yolks, which frequently happen to our domesticated poultry, and which, I believe, are so formed before impregnation, but which would be well worth attending to, both before and after impregnation; as it is probable, something valuable on this subject might be learnt from them. The latter circumstance, or that of deficiency of original nutriment, may be deduced from reverse analogy. There are, however, other kinds of monstrous births, which neither depend on deficiency of parts, or supernumerary ones; nor are owing to the conjunction of animals of different species; but which appear to be new conformations, or new dispositions of parts in respect to each other, and which, like the variation of colours and forms of our domesticated animals, and probably the sexual parts of all animals, may depend on the imagination of the male parent, which we now come to consider. VI. 1. The nice actions of the extremities of our various glands are exhibited in their various productions, which are believed to be made by the gland, and not previously to exist as such in the blood. Thus the glands, which constitute the liver, make bile; those of the stomach make gastric acid; those beneath the jaw, saliva; those of the ears, ear-wax; and the like. Every kind of gland must possess a peculiar irritability, and probably a sensibility, at the early state of its existence; and must be furnished with a nerve of sense, or of motion, to perceive, and to select, and to combine the particles, which compose the fluid it secretes. And this nerve of sense which perceives the different articles which compose the blood, must at least be conceived to be as fine and subtile an organ, as the optic or auditory nerve, which perceive light or sound. See Sect. XIV. 9. But in nothing is this nice action of the extremities of the blood-vessels so wonderful, as in the production of contagious matter. A small drop of variolous contagion diffused in the blood, or perhaps only by being inserted beneath the cuticle, after a time, (as about a quarter of a lunation,) excites the extreme vessels of the skin into certain motions, which produce a similar contagious material, filling with it a thousand pustules. So that by irritation, or by sensation in consequence of irritation, or by association of motions, a material is formed by the extremities of certain cutaneous vessels, exactly similar to the stimulating material, which caused the irritation, or consequent sensation, or association. Many glands of the body have their motions, and in consequence their secreted fluids, affected by pleasurable or painful ideas, since they are in many instances influenced by sensitive associations, as well as by the irritations of the particles of the passing blood. Thus the idea of meat, excited in the minds of hungry dogs, by their sense of vision, or of smell, increases the discharge of saliva, both in quantity and viscidity; as is seen in its hanging down in threads from their mouths, as they stand round a dinner-table. The sensations of pleasure, or of pain, of peculiar kinds, excite in the same manner a great discharge of tears; which appear also to be more saline at the time of their secretion, from their inflaming the eyes and eye-lids. The paleness from fear, and the blush of shame, and of joy, are other instances of the effects of painful, or pleasurable sensations, on the extremities of the arterial system. It is probable, that the pleasurable sensation excited in the stomach by food, as well as its irritation, contributes to excite into action the gastric glands, and to produce a greater secretion of their fluids. The same probably occurs in the secretion of bile; that is, that the pleasurable sensation excited in the stomach, affects this secretion by sensitive association, as well as by irritative association. And lastly it would seem, that all the glands in the body have their secreted fluids affected, in quantity and quality, by the pleasurable or painful sensations, which produce or accompany those secretions. And that the pleasurable sensations arising from these secretions may constitute the unnamed pleasure of exigence, which is contrary to what is meant by tedium vitæ, or ennui; and by which we sometimes feel ourselves happy, without being able to ascribe it to any mental cause, as after an agreeable meal, or in the beginning of intoxication. Now it would appear, that no secretion or excretion of fluid is attended with so much agreeable sensation, as that of the semen; and it would thence follow, that the glands, which perform this secretion, are more likely to be much affected by their catenations with pleasurable sensations. This circumstance is certain, that much more of this fluid is produced in a given time, when the object of its exclusion is agreeable to the mind. 2. A forceable argument, which shews the necessity of pleasurable sensation to copulation, is, that the act cannot be performed without it; it is easily interrupted by the pain of fear or bashfulness; and no efforts of volition or of irritation can effect this process, except such as induce pleasurable ideas or sensations. See Sect. XXXIII. 1. 1. A curious analogical circumstance attending hermaphrodite insects, as snails and worms, still further illustrates this theory; if the snail or worm could have impregnated itself, there might have been a saving of a large male apparatus; but as this is not so ordered by nature, but each snail and worm reciprocally receives and gives impregnation, it appears, that a pleasurable excitation seems also to have been required. This wonderful circumstance of many insects being hermaphrodites, and at the same time not having power to impregnate themselves, is attended to by Dr. Lister, in his Exercitationes Anatom. de Limacibus, p. 145; who, amongst many other final causes, which he adduces to account for it, adds, ut tam tristibus et frigidis animalibus majori cum voluptate perficiatur venus. There is, however, another final cause, to which this circumstance may be imputed: it was observed above, that vegetable buds and bulbs, which are produced without a mother, are always exact resemblances of their parent; as appears in grafting fruit-trees, and in the flower-buds of the dioiceous plants, which are always of the same sex on the same tree; hence those hermaphrodite insects, if they could have produced young without a mother, would not have been, capable of that change or improvement, which is seen in all other animals, and in those vegetables, which are procreated by the male embryon received and nourished by the female. And it is hence probable, that if vegetables could only have been produced by buds and bulbs, and not by sexual generation, that there would not at this time have existed one thousandth part of their present number of species; which have probably been originally mule-productions; nor could any kind of improvement or change have happened to them, except by the difference of soil or climate. 3. I conclude, that the imagination of the male at the time of copulation, or at the time of the secretion of the semen, may so affect this secretion by irritative or sensitive association, as described in No. 5. 1. of this section, as to cause the production of similarity of form and of features, with the distinction of sex; as the motions of the chissel of the turner imitate or correspond with those of the ideas of the artist. It is not here to be understood, that the first living fibre, which is to form an animal, is produced with any similarity of form to the future animal; but with propensities, or appetences, which shall produce by accretion of parts the similarity of form, feature, or sex, corresponding to the imagination of the father. Our ideas are movements of the nerves of sense, as of the optic nerve in recollecting visible ideas, suppose of a triangular piece of ivory. The fine moving fibres of the retina act in a manner to which I give the name of white; and this action is confined to a defined part of it; to which figure I give the name of triangle. And it is a preceding pleasurable sensation existing in my mind, which occasions me to produce this particular motion of the retina, when no triangle is present. Now it is probable, that the acting fibres of the ultimate terminations of the secreting apertures of the vessels of the testes, are as fine as those of the retina; and that they are liable to be thrown into that peculiar action, which marks the sex of the secreted embryon, by sympathy with the pleasurable motions of the nerves of vision or of touch; that is, with certain ideas of imagination. From hence it would appear, that the world has long been mistaken in ascribing great power to the imagination of the female, whereas from this account of it, the real power of imagination, in the act of generation, belongs solely to the male. See Sect. XII. 3. 3. It may be objected to this theory, that a man may be supposed to have in his mind, the idea of the form and features of the female, rather than his own, and therefore there should be a greater number of female births. On the contrary, the general idea of our own form occurs to every one almost perpetually, and is termed consciousness of our existence, and thus may effect, that the number of males surpasses that of females. See Sect. XV. 3. 4. and XVIII. 13. And what further confirms this idea is, that the male children most frequently resemble the father in form, or feature, as well as in sex; and the female most frequently resemble the mother, in feature, and form, as well as in sex. It may again be objected, if a female child sometimes resembles the father, and a male child the mother, the ideas of the father, at the time of procreation, must suddenly change from himself to the mother, at the very instant, when the embryon is secreted or formed. This difficulty ceases when we consider, that it is as easy to form an idea of feminine features with male organs of reproduction, or of male features with female ones, as the contrary; as we conceive the idea of a sphinx or mermaid as easily and as distinctly as of a woman. Add to this, that at the time of procreation the idea of the male organs, and of the female features, are often both excited at the same time, by contact, or by vision. I ask, in my turn, is the sex of the embryon produced by accident? Certainly whatever is produced has a cause; but when this cause is too minute for our comprehension, the effect is said in common language to happen by chance, as in throwing a certain number on dice. Now what cause can occasionally produce the male or female character of the embryon, but the peculiar actions of those glands, which form the embryon? And what can influence or govern these actions of the gland, but its associations or catenations with other sensitive motions? Nor is this more extraordinary, than that the catenations of irritative motions with the apparent vibrations of objects at sea should produce sickness of the stomach; or that a nauseous story should occasion vomiting. 4. An argument, which evinces the effect of imagination on the first rudiment of the embryon, may be deduced from the production of some peculiar monsters. Such, for instance, as those which have two heads joined to one body, and those which have two bodies joined to one head; of which frequent examples occur amongst our domesticated quadrupeds, and poultry. It is absurd to suppose, that such forms could exist in primordial germs, as explained in No. IV. 4. of this section. Nor is it possible, that such deformities could be produced by the growth of two embryons, or living filaments; which should afterwards adhere together; as the head and tail part of different polypi are said to do (Blumenbach on Generation, Cadel, London); since in that case one embryon, or living filament, must have begun to form one part first, and the other another part first. But such monstrous conformations become less difficult to comprehend, when they are considered as an effect of the imagination, as before explained, on the living filament at the time of its secretion; and that such duplicature of limbs were produced by accretion of new parts, in consequence of propensities, or animal appetencies thus acquired from the male parent. For instance, I can conceive, if a turkey-cock should behold a rabbit, or a frog, at the time of procreation, that it might happen, that a forcible or even a pleasurable idea of the form of a quadruped might so occupy his imagination, as to cause a tendency in the nascent filament to resemble such a form, by the apposition of a duplicature of limbs. Experiments on the production of mules and monsters would be worthy the attention of a Spallanzani, and might throw much light upon this subject, which at present must be explained by conjectural analogies. The wonderful effect of imagination, both in the male and female parent, is shewn in the production of a kind of milk in the crops both of the male and female pigeons after the birth of their young, as observed by Mr. Hunter, and mentioned before. To this should be added, that there are some instances of men having had milk secreted in their breasts, and who have given suck to children, as recorded by Mr. Buffon. This effect of imagination, of both the male and female parent, seems to have been attended to in very early times; Jacob is said not only to have placed rods of trees, in part stripped of their bark, so as to appear spotted, but also to have placed spotted lambs before the flocks, at the time of their copulation. Genesis, chap. xxx. verse 40. 5. In respect to the imagination of the mother, it is difficult to comprehend, how this can produce any alteration in the fetus, except by affecting the nutriment laid up for its first reception, as described in No. V. 2. of this section, or by affecting the nourishment or oxygenation with which she supplies it afterwards. Perpetual anxiety may probably affect the secretion of the liquor amnii into the uterus, as it enfeebles the whole system; and sudden fear is a frequent cause of miscarriage; for fear, contrary to joy, decreases for a time the action of the extremities of the arterial system; hence sudden paleness succeeds, and a shrinking or contraction of the vessels of the skin, and other membranes. By this circumstance, I imagine, the terminations of the placental vessels are detached from their adhesions, or insertions, into the membrane of the uterus; and the death of the child succeeds, and consequent miscarriage. Of this I recollect a remarkable instance, which could be ascribed to no other cause, and which I shall therefore relate in few words. A healthy young woman, about twenty years of age, had been about five months pregnant, and going down into her cellar to draw some beer, was frighted by a servant boy starting up from behind the barrel, where he had concealed himself with design to alarm the maid-servant, for whom he mistook his mistress. She came with difficulty up stairs, began to flood immediately, and miscarried in a few hours. She has since borne several children, nor ever had any tendency to miscarry of any of them. 6. In respect to the power of the imagination of the male over the form, colour, and sex of the progeny, the following instances have fallen under my observation, and may perhaps be found not very unfrequent, if they were more attended to. I am acquainted with a gentleman, who has one child with dark hair and eyes, though his lady and himself have light hair and eyes; and their other four children are like their parents. On observing this dissimilarity of one child to the others he assured me, that he believed it was his own imagination, that produced the difference; and related to me the following story. He said, that when his lady lay in of her third child, he became attached to a daughter of one of his inferior tenants, and offered her a bribe for her favours in vain; and afterwards a greater bribe, and was equally unsuccessful; that the form of this girl dwelt much in his mind for some weeks, and that the next child, which was the dark-ey'd young lady above mentioned, was exceedingly like, in both features and colour, to the young woman who refused his addresses. To this instance I must add, that I have known two families, in which, on account of an intailed estate in expectation, a male heir was most eagerly desired by the father; and on the contrary, girls were produced to the seventh in one, and to the ninth in another; and then they had each of them a son. I conclude, that the great desire of a male heir by the father produced rather a disagreeable than an agreeable sensation; and that his ideas dwelt more on the fear of generating a female, than on the pleasurable sensations or ideas of his own male form or organs at the time of copulation, or of the secretion of the semen; and that hence the idea of the female character was more present to his mind than that of the male one; till at length in despair of generating a male these ideas ceased, and those of the male character presided at the genial hour. 7. Hence I conclude, that the act of generation cannot exist without being accompanied with ideas, and that a man must have at that time either a general idea of his own male form, or of the form of his male organs; or an idea of the female form, or of her organs; and that this marks the sex, and the peculiar resemblances of the child to either parent. From whence it would appear, that the phalli, which were hung round the necks of the Roman ladies, or worn in their hair, might have effect in producing a greater proportion of male children; and that the calipædia, or art of begetting beautiful children, and of procreating either males or females, may be taught by affecting the imagination of the male-parent; that is, by the fine extremities of the seminal glands, imitating the actions of the organs of sense either of sight or touch. But the manner of accomplishing this cannot be unfolded with sufficient delicacy for the public eye; but may be worth the attention of those, who are seriously interested in the procreation of a male or female child. _Recapitulation._ VII. 1. A certain quantity of nutritive particles are produced by the female parent before impregnation, which require no further digestion, secretion, or oxygenation. Such are seen in the unimpregnated eggs of birds, and in the unimpregnated seed-vessels of vegetables. 2. A living filament is produced by the male, which being inserted amidst these first nutritive particles, is stimulated into action by them; and in consequence of this action, some of the nutritive particles are embraced, and added to the original living filament; in the same manner as common nutrition is performed in the adult animal. 3. Then this new organization, or additional part, becomes stimulated by the nutritive particles in its vicinity, and sensation is now superadded to irritation; and other particles are in consequence embraced, and added to the living filament; as is seen in the new granulations of flesh in ulcers. By the power of association, or by irritation, the parts already produced continue their motions, and new ones are added by sensation, as above mentioned; and lastly by volition, which last sensorial power is proved to exist in the fetus in its maturer age, because it has evidently periods of activity and of sleeping; which last is another word for a temporary suspension of volition. The original living filament may be conceived to possess a power of repulsing the particles applied to certain parts of it, as well as of embracing others, which stimulate other parts of it; as these powers exist in different parts of the mature animal; thus the mouth of every gland embraces the particles or fluid, which suits its appetency; and its excretory duct repulses those particles, which are disagreeable to it. 4. Thus the outline or miniature of the new animal is produced gradually, but in no great length of time; because the original nutritive particles require no previous preparation by digestion, secretion, and oxygenation: but require simply the selection and apposition, which is performed by the living filament. Mr. Blumenbach says, that he possesses a human fetus of only five weeks old, which is the size of a common bee, and has all the features of the face, every finger, and every toe, complete; and in which the organs of generation are distinctly seen. P. 76. In another fetus, whose head was not larger than a pea, the whole of the basis of the skull with all its depressions, apertures, and processes, were marked in the most sharp and distinct manner, though without any ossification. Ib. 5. In some cases by the nutriment originally deposited by the mother the filament acquires parts not exactly similar to those of the father, as in the production of mules and mulattoes. In other cases, the deficiency of this original nutriment causes deficiencies of the extreme parts of the fetus, which are last formed, as the fingers, toes, lips. In other cases, a duplicature of limbs are caused by the superabundance of this original nutritive fluid, as in the double yolks of eggs, and the chickens from them with four legs and four wings. But the production of other monsters, as those with two heads, or with parts placed in wrong situations, seems to arise from the imagination of the father being in some manner imitated by the extreme vessels of the seminal glands; as the colours of the spots on eggs, and the change of the colour of the hair and feathers of animals by domestication, may be caused in the same manner by the imagination of the mother. 6. The living filament is a part of the father, and has therefore certain propensities, or appetencies, which belong to him; which may have been gradually acquired during a million of generations, even from the infancy of the habitable earth; and which now possesses such properties, as would render, by the apposition of nutritious particles, the new fetus exactly similar to the father; as occurs in the buds and bulbs of vegetables, and in the polypus, and tænia or tape-worm. But as the first nutriment is supplied by the mother, and therefore resembles such nutritive particles, as have been used for her own nutriment or growth, the progeny takes in part of the likeness of the mother. Other similarity of the excitability, or of the form of the male parent, such as the broad or narrow shoulders, or such as constitute certain hereditary diseases, as scrophula, epilepsy, insanity, have their origin produced in one or perhaps two generations; as in the progeny of those who drink much vinous spirits; and those hereditary propensities cease again, as I have observed, if one or two sober generations succeed; otherwise the family becomes extinct. This living filament from the father is also liable to have its propensities, or appetencies, altered at the time of its production by the imagination of the male parent; the extremities of the seminal glands imitating the motions of the organs of sense; and thus the sex of the embryon is produced; which may be thus made a male or a female by affecting the imagination of the father at the time of impregnation. See Sect. XXXIX. 6. 3. and 7. 7. After the fetus is thus completely formed together with its umbilical vessels and placenta, it is now supplied with a different kind of food, as appears by the difference of consistency of the different parts of the white of the egg, and of the liquor amnii, for it has now acquired organs for digestion or secretion, and for oxygenation, though they are as yet feeble; which can in some degree change, as well as select, the nutritive particles, which are now presented to it. But may yet be affected by the deficiency of the quantity of nutrition supplied by the mother, or by the degree of oxygenation supplied to its placenta by the maternal blood. The augmentation of the complete fetus by additional particles of nutriment is not accomplished by distention only, but by apposition to every part both external and internal; each of which acquires by animal appetencies the new addition of the particles which it wants. And hence the enlarged parts are kept similar to their prototypes, and may be said to be extended; but their extension must be conceived only as a necessary consequence of the enlargement of all their parts by apposition of new particles. Hence the new apposition of parts is not produced by capillary attraction, because the whole is extended; whereas capillary attraction would rather tend to bring the sides of flexible tubes together, and not to distend them. Nor is it produced by chemical affinities, for then a solution of continuity would succeed, as when sugar is dissolved in water; but it is produced by an animal process, which is the consequence of irritation, or sensation; and which may be termed animal appetency. This is further evinced from experiments, which have been instituted to shew, that a living muscle of an animal body requires greater force to break it, than a similar muscle of a dead body. Which evinces, that besides the attraction of cohesion, which all matter possesses, and besides the chemical attractions of affinities, which hold many bodies together, there is an animal adhesion, which adds vigour to these common laws of the inanimate world. 8. At the nativity of the child it deposits the placenta or gills, and by expanding its lungs acquires more plentiful oxygenation from the currents of air, which it must now continue perpetually to respire to the end of its life; as it now quits the liquid element, in which it was produced, and like the tadpole, when it changes into a frog, becomes an aerial animal. 9. As the habitable parts of the earth have been, and continue to be, perpetually increasing by the production of sea-shells and corallines, and by the recrements of other animals, and vegetables; so from the beginning of the existence of this terraqueous globe, the animals, which inhabit it, have constantly improved, and are still in a state of progressive improvement. This idea of the gradual generation of all things seems to have been as familiar to the ancient philosophers as to the modern ones; and to have given rise to the beautiful hieroglyphic figure of the [Greek: proton ôon], or first great egg, produced by NIGHT, that is, whose origin is involved in obscurity, and animated by [Greek: eros], that is, by DIVINE LOVE; from whence proceeded all things which exist. _Conclusion._ VIII. 1. Cause and effect may be considered as the progression, or successive motions, of the parts of the great system of Nature. The state of things at this moment is the effect of the state of things, which existed in the preceding moment; and the cause of the state of things, which shall exist in the next moment. These causes and effects may be more easily comprehended, if motion be considered as a change of the figure of a group of bodies, as proposed in Sect. XIV. 2. 2. inasmuch as our ideas of visible or tangible objects are more distinct, than our abstracted ideas of their motions. Now the change of the configuration of the system of nature at this moment must be an effect of the preceding configuration, for a change of configuration cannot exist without a previous configuration; and the proximate cause of every effect must immediately precede that effect. For example, a moving ivory ball could not proceed onwards, unless it had previously began to proceed; or unless an impulse had been previously given it; which previous motion or impulse constitutes a part of the last situation of things. As the effects produced in this moment of time become causes in the next, we may consider the progressive motions of objects as a chain of causes only; whose first link proceeded from the great Creator, and which have existed from the beginning of the created universe, and are perpetually proceeding. 2. These causes may be conveniently divided into two kinds, efficient and inert causes, according with the two kinds of entity supposed to exist in the natural world, which may be termed matter and spirit, as proposed in Sect. I. and further treated of in Sect. XIV. The efficient causes of motion, or new configuration, consist either of the principle of general gravitation, which actuates the sun and planets; or of the principle of particular gravitation, as in electricity, magnetism, heat; or of the principle of chemical affinity, as in combustion, fermentation, combination; or of the principle of organic life, as in the contraction of vegetable and animal fibres. The inert causes of motion, or new configuration, consist of the parts of matter, which are introduced within the spheres of activity of the principles above described. Thus, when an apple falls on the ground, the principle of gravitation is the efficient cause, and the matter of the apple the inert cause. If a bar of iron be approximated to a magnet, it may be termed the inert cause of the motion, which brings these two bodies into contact; while the magnetic principle may be termed the efficient cause. In the same manner the fibres, which constitute the retina, may be called the inert cause of the motions of that organ in vision, while the sensorial power may be termed the efficient cause. 3. Another more common distribution of the perpetual chain of causes and effects, which constitute the motions, or changing configurations, of the natural world, is into active and passive. Thus, if a ball in motion impinges against another ball at rest, and communicates its motion to it, the former ball is said to act, and the latter to be acted upon. In this sense of the words a magnet is said to attract iron; and the prick of a spur to stimulate a horse into exertion; so that in this view of the works of nature all things may be said either simply to exist, or to exist as causes, or to exist as effects; that is, to exist either in an active or passive state. This distribution of objects, and their motions, or changes of position, has been found so convenient for the purposes of common life, that on this foundation rests the whole construction or theory of language. The names of the things themselves are termed by grammarians Nouns, and their modes of existence are termed Verbs. The nouns are divided into substantives, which denote the principal things spoken of; and into adjectives, which denote some circumstances, or less kinds of things, belonging to the former. The verbs are divided into three kinds, such as denote the existence of things simply, as, to be; or their existence in an active state, as, to eat; or their existence in a passive state, as, to be eaten. Whence it appears, that all languages consist only of nouns and verbs, with their abbreviations for the greater expedition of communicating our thoughts; as explained in the ingenious work of Mr. Horne Tooke, who has unfolded by a single flash of light the whole theory of language, which had so long lain buried beneath the learned lumber of the schools. Diversions of Purley. Johnson. London. 4. A third division of causes has been into proximate and remote; these have been much spoken of by the writers on medical subjects, but without sufficient precision. If to proximate and remote causes we add proximate and remote effects, we shall include four links of the perpetual chain of causation; which will be more convenient for the discussion of many philosophical subjects. Thus if a particle of chyle be applied to the mouth of a lacteal vessel, it may be termed the remote cause of the motions of the fibres, which compose the mouth of that lacteal vessel; the sensorial power is the proximate cause; the contraction of the fibres of the mouth of the vessel is the proximate effect; and their embracing the particle of chyle is the remote effect; and these four links of causation constitute absorption. Thus when we attend to the rising sun, first the yellow rays of light stimulate the sensorial power residing in the extremities of the optic nerve, this is the remote cause. 2. The sensorial power is excited into a state of activity, this is the proximate cause. 3. The fibrous extremities of the optic nerve are contracted, this is the proximate effect. 4. A pleasurable or painful sensation is produced in consequence of the contraction of these fibres of the optic nerve, this is the remote effect; and these four links of the chain of causation constitute the sensitive idea, or what is commonly termed the sensation of the rising sun. 5. Other causes have been announced by medical writers under the names of causa procatarctica, and causa proegumina, and causa sine quâ non. All which are links more or less distant of the chain of remote causes. To these must be added the final cause, so called by many authors, which means the motive, for the accomplishment of which the preceding chain of causes was put into action. The idea of a final cause, therefore, includes that of a rational mind, which employs means to effect its purposes; thus the desire of preserving himself from the pain of cold, which he has frequently experienced, induces the savage to construct his hut; the fixing stakes into the ground for walls, branches of trees for rafters, and turf for a cover, are a series of successive voluntary exertions; which are so many means to produce a certain effect. This effect of preserving himself from cold, is termed the final cause; the construction of the hut is the remote effect; the action of the muscular fibres of the man, is the proximate effect; the volition, or activity of desire to preserve himself from cold, is the proximate cause; and the pain of cold, which excited that desire, is the remote cause. 6. This perpetual chain of causes and effects, whose first link is rivetted to the throne of GOD, divides itself into innumerable diverging branches, which, like the nerves arising from the brain, permeate the most minute and most remote extremities of the system, diffusing motion and sensation to the whole. As every cause is superior in power to the effect, which it has produced, so our idea of the power of the Almighty Creator becomes more elevated and sublime, as we trace the operations of nature from cause to cause, climbing up the links of these chains of being, till we ascend to the Great Source of all things. Hence the modern discoveries in chemistry and in geology, by having traced the causes of the combinations of bodies to remoter origins, as well as those in astronomy, which dignify the present age, contribute to enlarge and amplify our ideas of the power of the Great First Cause. And had those ancient philosophers, who contended that the world was formed from atoms, ascribed their combinations to certain immutable properties received from the hand of the Creator, such as general gravitation, chemical affinity, or animal appetency, instead of ascribing them to a blind chance; the doctrine of atoms, as constituting or composing the material world by the variety of their combinations, so far from leading the mind to atheism, would strengthen the demonstration of the existence of a Deity, as the first cause of all things; because the analogy resulting from our perpetual experience of cause and effect would have thus been exemplified through universal nature. _The heavens declare the glory of _GOD_, and the firmament sheweth his handywork! One day telleth another, and one night certifieth another; they have neither speech nor language, yet their voice is gone forth into all lands, and their words into the ends of the world. Manifold are thy works, _O LORD!_ in wisdom hast thou made them all._ Psal. xix. civ. * * * * * SECT. XL. On the OCULAR SPECTRA of Light and Colours, by Dr. R. W. Darwin, of Shrewsbury. Reprinted, by Permission, from the Philosophical Transactions, Vol. LXXVI. p. 313. _Spectra of four kinds._ 1. _Activity of the retina in vision._ 2. _Spectra from defect of sensibility._ 3. _Spectra from excess of sensibility_. 4. _Of direct ocular spectra._ 5. _Greater stimulus excites the retina into spasmodic action._ 6. _Of reverse ocular spectra._ 7. _Greater stimulus excites the retina into various successive spasmodic actions._ 8. _Into fixed spasmodic action._ 9. _Into temporary paralysis._ 10. _Miscellaneous remarks;_ 1. _Direct and reverse spectra at the same time. A spectral halo. Rule to predetermine the colours of spectra._ 2. _Variation of spectra from extraneous light._ 3. _Variation of spectra in number, figure, and remission._ 4. _Circulation of the blood in the eye is visible._ 5. _A new way of magnifying objects. Conclusion._ When any one has long and attentively looked at a bright object, as at the setting sun, on closing his eyes, or removing them, an image, which resembles in form the object he was attending to, continues some time to be visible; this appearance in the eye we shall call the ocular spectrum of that object. These ocular spectra are of four kinds: 1st, Such as are owing to a less sensibility of a defined part of the retina; or _spectra from defect of sensibility._ 2d, Such as are owing to a greater sensibility of a defined part of the retina; or _spectra from excess of sensibility_. 3d, Such as resemble their object in its colour as well as form; which may be termed _direct ocular spectra_. 4th, Such as are of a colour contrary to that of their object; which may be termed _reverse ocular spectra_. The laws of light have been most successfully explained by the great Newton, and the perception of visible objects has been ably investigated by the ingenious Dr. Berkeley and M. Malebranche; but these minute phenomena of vision have yet been thought reducible to no theory, though many philosophers have employed a considerable degree of attention upon them: among these are Dr. Jurin, at the end of Dr. Smith's Optics; M. Æpinus, in the Nov. Com. Petropol. V. 10.; M. Beguelin, in the Berlin Memoires, V. II. 1771; M. d'Arcy, in the Histoire de l'Acad. des Scienc. 1765; M. de la Hire; and, lastly, the celebrated M. de Buffon, in the Memoires de l'Acad. des Scien. who has termed them accidental colours, as if subjected to no established laws, Ac. Par. 1743. M. p. 215. I must here apprize the reader, that it is very difficult for different people to give the same names to various shades of colours; whence, in the following pages, something must be allowed, if on repeating the experiments the colours here mentioned should not accurately correspond with his own names of them. I. _Activity of the Retina in Vision._ From the subsequent experiments it appears, that the retina is in an active not in a passive state during the existence of these ocular spectra; and it is thence to be concluded, that all vision is owing to the activity of this organ. 1. Place a piece of red silk, about an inch in diameter, as in plate 1, at Sect. III. 1., on a sheet of white paper, in a strong light; look steadily upon it from about the distance of half a yard for a minute; then closing your eyelids cover them with your hands, and a green spectrum will be seen in your eyes, resembling in form the piece of red silk: after some time, this spectrum will disappear and shortly reappear; and this alternately three or four times, if the experiment is well made, till at length it vanishes entirely. 2. Place on a sheet of white paper a circular piece of blue silk, about four inches in diameter, in the sunshine; cover the center of this with a circular piece of yellow silk, about three inches in diameter; and the center of the yellow silk with a circle of pink silk, about two inches in diameter; and the center of the pink silk with a circle of green silk, about one inch in diameter; and the centre of this with a circle of indigo, about half an inch in diameter; make a small speck with ink in the very center of the whole, as in plate 3, at Sect. III. 3. 6.; look steadily for a minute on this central spot, and then closing your eyes, and applying your hand at about an inch distance before them, so as to prevent too much or too little light from passing through the eyelids, you will see the most beautiful circles of colours that imagination can conceive, which are most resembled by the colours occasioned by pouring a drop or two of oil on a still lake in a bright day; but these circular irises of colours are not only different from the colours of the silks above mentioned, but are at the same time perpetually changing as long as they exist. 3. When any one in the dark presses either corner of his eye with his finger, and turns his eye away from his finger, he will see a circle of colours like those in a peacock's tail: and a sudden flash of light is excited in the eye by a stroke on it. (Newton's Opt. Q. 16.) 4. When any one turns round rapidly on one foot, till he becomes dizzy, and falls upon the ground, the spectra of the ambient objects continue to present themselves in rotation, or appear to librate, and he seems to behold them for some time still in motion. From all these experiments it appears, that the spectra in the eye are not owing to the mechanical impulse of light impressed on the retina, nor to its chemical combination with that organ, nor to the absorption and emission of light, as is observed in many bodies; for in all these cases the spectra must either remain uniformly, or gradually diminish; and neither their alternate pretence and evanescence as in the first experiment, nor the perpetual changes of their colours as in the second, nor the flash of light or colours in the pressed eye as in the third, nor the rotation or libration of the spectra as in the fourth, could exist. It is not absurd to conceive, that the retina may be stimulated into motion, as well as the red and white muscles which form our limbs and vessels; since it consists of fibres, like those, intermixed with its medullary substance. To evince this structure, the retina of an ox's eye was suspended in a glass of warm water, and forcibly torn in a few places; the edges of these parts appeared jagged and hairy, and did not contract, and become smooth like simple mucus, when it is distended till it breaks; which shews that it consists of fibres; and that its fibrous construction became still more distinct to the sight, by adding some caustic alkali to the water, as the adhering mucus was first eroded, and the hair-like fibres remained floating in the vessel. Nor does the degree of transparency of the retina invalidate the evidence of its fibrous structure, since Leeuwenhoek has shewn that the crystalline humour itself consists of fibres. (Arcana Naturæ, V. 1. p. 70.) Hence it appears, that as the muscles have larger fibres intermixed with a smaller quantity of nervous medulla, the organ of vision has a greater quantity of nervous medulla intermixed with smaller fibres; and it is probable that the locomotive muscles, as well as the vascular ones, of microscopic animals have much greater tenuity than these of the retina. And besides the similar laws, which will be shewn in this paper to govern alike the actions of the retina and of the muscles, there are many other analogies which exist between them. They are both originally excited into action by irritations, both are nearly in the same quantity of time, are alike strengthened or fatigued by exertion, are alike painful if excited into action when they are in an inflamed state, are alike liable to paralysis, and to the torpor of old age. II. OF SPECTRA FROM DEFECT OF SENSIBILITY. _The retina is not so easily excited into action by less irritation after having been lately subjected to greater._ 1. When any one passes from the bright daylight into a darkened room, the irises of his eyes expand themselves to their utmost extent in a few seconds of time; but it is very long before the optic nerve, after having been stimulated by the greater light of the day, becomes sensible of the less degree of it in the room; and, if the room is not too obscure, the irises will again contract themselves in some degree, as the sensibility of the retina returns. 2. Place about half an inch square of white paper on a black hat, and looking steadily on the center of it for a minute, remove your eyes to a sheet of white paper; and after a second or two a dark square will be seen on the white paper, which will continue some time. A similar dark square will be seen in the closed eye, if light be admitted through the eyelids. So after looking at any luminous object of a small size, as at the sun, for a short time, so as not much to fatigue the eyes, this part of the retina becomes less sensible to smaller quantities of light; hence, when the eyes are turned on other less luminous parts of the sky, a dark spot is seen resembling the shape of the sun, or other luminous object which we last beheld. This is the source of one kind of the dark-coloured _muscæ volitantes_. If this dark spot lies above the center of the eye, we turn our eyes that way, expecting to bring it into the center of the eye, that we may view it more distinctly; and in this case the dark spectrum seems to move upwards. If the dark spectrum is found beneath the centre of the eye, we pursue it from the same motive, and it seems to move downwards. This has given rise to various conjectures of something floating in the aqueous humours of the eyes; but whoever, in attending to these spots, keeps his eyes unmoved by looking steadily at the corner of a cloud, at the same time that he observes the dark spectra, will be thoroughly convinced, that they have no motion but what is given to them by the movement of our eyes in pursuit of them. Sometimes the form of the spectrum, when it has been received from a circular luminous body, will become oblong; and sometimes it will be divided into two circular spectra, which is not owing to our changing the angle made by the two optic axises, according to the distance of the clouds or other bodies to which the spectrum is supposed to be contiguous, but to other causes mentioned in No. X. 3. of this section. The apparent size of it will also be variable according to its supposed distance. As these spectra are more easily observable when our eyes are a little weakened by fatigue, it has frequently happened, that people of delicate constitutions have been much alarmed at them, fearing a beginning decay of their sight, and have thence fallen into the hands of ignorant oculists; but I believe they never are a prelude to any other disease of the eye, and that it is from habit alone, and our want of attention to them, that we do not see them on all objects every hour of our lives. But as the nerves of very weak people lose their sensibility, in the same manner as their muscles lose their activity, by a small time of exertion, it frequently happens, that sick people in the extreme debility of fevers are perpetually employed in picking something from the bed-clothes, occasioned by their mistaking the appearance of these _muscæ volitantes_ in their eyes. Benvenuto Celini, an Italian artist, a man of strong abilities, relates, that having passed the whole night on a distant mountain with some companions and a conjurer, and performed many ceremonies to raise the devil, on their return in the morning to Rome, and looking up when the sun began to rise, they saw numerous devils run on the tops of the houses, as they passed along; so much were the spectra of their weakened eyes magnified by fear, and made subservient to the purposes of fraud or superstition. (Life of Ben. Celini.) 3. Place a square inch of white paper on a large piece of straw-coloured silk; look steadily some time on the white paper, and then move the centre of your eyes on the silk, and a spectrum of the form of the paper will appear on the silk, of a deeper yellow than the other part of it: for the central part of the retina, having been some time exposed to the stimulus of a greater quantity of white light, is become less sensible to a smaller quantity of it, and therefore sees only the yellow rays in that part of the straw-coloured silk. Facts similar to these are observable in other parts of our system: thus, if one hand be made warm, and the other exposed to the cold, and then both of them immersed in subtepid water, the water is perceived warm to one hand, and cold to the other; and we are not able to hear weak sounds for some time after we have been exposed to loud ones; and we feel a chilliness on coming into an atmosphere of temperate warmth, after having been some time confined in a very warm room: and hence the stomach, and other organs of digestion, of those who have been habituated to the greater stimulus of spirituous liquor, are not excited into their due action by the less stimulus of common food alone; of which the immediate consequence is indigestion and hypochondriacism. III. OF SPECTRA FROM EXCESS OF SENSIBILITY. _The retina is more easily excited into action by greater irritation after having been lately subjected to less._ 1. If the eyes are closed, and covered perfectly with a hat, for a minute or two, in a bright day; on removing the hat a red or crimson light is seen through the eyelids. In this experiment the retina, after being some time kept in the dark, becomes so sensible to a small quantity of light, as to perceive distinctly the greater quantity of red rays than of others which pass through the eyelids. A similar coloured light is seen to pass through the edges of the fingers, when the open hand is opposed to the flame of a candle. 2. If you look for some minutes steadily on a window in the beginning of the evening twilight, or in a dark day, and then move your eyes a little, so that those parts of the retina, on which the dark frame-work of the window was delineated, may now fall on the glass part of it, many luminous lines, representing the frame-work, will appear to lie across the glass panes: for those parts of the retina, which were before least stimulated by the dark frame-work, are now more sensible to light than the other parts of the retina which were exposed to the more luminous parts of the window, 3. Make with ink on white paper a very black spot, about half an inch in diameter, with a tail about an inch in length, so as to represent a tadpole, as in plate 2, at Sect. III. 3. 3.; look steadily for a minute on this spot, and, on moving the eye a little, the figure of the tadpole will be seen on the white part of the paper, which figure of the tadpole will appear whiter or more luminous than the other parts of the white paper; for the part of the retina on which the tadpole was delineated, is now more sensible to light, than the other parts of it, which were exposed to the white paper. This experiment is mentioned by Dr. Irwin, but is not by him ascribed to the true cause, namely, the greater sensibility of that part of the retina which has been exposed to the black spot, than of the other parts which had received the white field of paper, which is put beyond a doubt by the next experiment. 4. On closing the eyes after viewing the black spot on the white paper, as in the foregoing experiment, a red spot is seen of the form of the black spot: for that part of the retina, on which the black spot was delineated, being now more sensible to light than the other parts of it, which were exposed to the white paper, is capable of perceiving the red rays which penetrate the eyelids. If this experiment be made by the light of a tallow candle, the spot will be yellow instead of red; for tallow candles abound much with yellow light, which passes in greater quantity and force through the eyelids than blue tight; hence the difficulty of distinguishing blue and green by this kind of candle light. The colour of the spectrum may possibly vary in the daylight, according to the different colour of the meridian or the morning or evening light. M. Beguelin, in the Berlin Memoires, V. II. 1771, observes, that, when he held a book so that the sun shone upon his half-closed eyelids, the black letters, which he had long inspected, became red, which must have been thus occasioned. Those parts of the retina which had received for some time the black letters, were so much more sensible than those parts which had been opposed to the white paper, that to the former the red light, which passed through the eyelids, was perceptible. There is a similar story told, I think, in de Voltaire's Historical Works, of a Duke of Tuscany, who was playing at dice with the general of a foreign army, and, believing he saw bloody spots upon the dice, portended dreadful events, and retired in confusion. The observer, after looking for a minute on the black spots of a die, and carelessly closing his eyes, on a bright day; would see the image of a die with red spots upon it, as above explained. 5. On emerging from a dark cavern, where we have long continued, the light of a bright day becomes intolerable to the eye for a considerable time, owing to the excess of sensibility existing in the eye, after having been long exposed to little or no stimulus. This occasions us immediately to contract the iris to its smallest aperture, which becomes again gradually dilated, as the retina becomes accustomed to the greater stimulus of the daylight. The twinkling of a bright star, or of a distant candle in the night, is perhaps owing to the same cause. While we continue to look upon these luminous objects, their central parts gradually appear paler, owing to the decreasing sensibility of the part of the retina exposed to their light; whilst, at the same time, by the unsteadiness of the eye, the edges of them are perpetually falling on parts of the retina that were just before exposed to the darkness of the night, and therefore tenfold more sensible to light than the part on which the star or candle had been for some time delineated. This pains the eye in a similar manner as when we come suddenly from a dark room into bright daylight, and gives the appearance of bright scintillations. Hence the stars twinkle most when the night is darkest, and do not twinkle through telescopes, as observed by Musschenbroeck; and it will afterwards be seen why this twinkling is sometimes of different colours when the object is very bright, as Mr. Melvill observed in looking at Sirius. For the opinions of others on this subject, see Dr. Priestley's valuable History of Light and Colours, p. 494. Many facts observable in the animal system are similar to these; as the hot glow occasioned by the usual warmth of the air, or our clothes, on coming out of a cold bath; the pain of the fingers on approaching the fire after having handled snow; and the inflamed heels from walking in snow. Hence those who have been exposed to much cold have died on being brought to a fire, or their limbs have become so much inflamed as to mortify. Hence much food or wine given suddenly to those who have almost perished by hunger has destroyed them; for all the organs of the famished body are now become so much more irritable to the stimulus of food and wine, which they have long been deprived of, that inflammation is excited, which terminates in gangrene or fever. IV. OF DIRECT OCULAR SPECTRA. _A quantity of stimulus somewhat greater than natural excites the retina into spasmodic action, which ceases in a few seconds._ A certain duration and energy of the stimulus of light and colours excites the perfect action of the retina in vision; for very quick motions are imperceptible to us, as well as very slow ones, as the whirling of a top, or the shadow on a sun-dial. So perfect darkness does not affect the eye at all; and excess of light produces pain, not vision. 1. When a fire-coal is whirled round in the dark, a lucid circle remains a considerable time in the eye; and that with so much vivacity of light, that it is mistaken for a continuance of the irritation of the object. In the same manner, when a fiery meteor shoots across the night, it appears to leave a long lucid train behind it, part of which, and perhaps sometimes the whole, is owing to the continuance of the action of the retina after having been thus vividly excited. This is beautifully illustrated by the following experiment: fix a paper sail, three or four inches in diameter, and made like that of a smoke jack, on a tube of pasteboard; on looking through the tube at a distant prospect, some disjointed parts of it will be seen through the narrow intervals between the sails; but as the fly begins to revolve, these intervals appear larger; and when it revolves quicker, the whole prospect is seen quite as distinct as if nothing intervened, though less luminous. [Illustration: Fig. 3.] 2. Look through a dark tube, about half a yard long, at the area of a yellow circle of half an inch diameter, lying upon a blue area of double that diameter, for half a minute; and on closing your eyes the colours of the spectrum will appear similar to the two areas, as in fig. 3.; but if the eye is kept too long upon them, the colours of the spectrum will be the reverse of those upon the paper, that is, the internal circle will become blue, and the external area yellow; hence some attention is required in making this experiment. 3. Place the bright flame of a spermaceti candle before a black object in the night; look steadily at it for a short time, till it is observed to become somewhat paler; and on closing the eyes, and covering them carefully, but not so as to compress them, the image of the blazing candle will continue distinctly to be visible. 4. Look steadily, for a short time, at a window in a dark day, as in Exp. 2. Sect. III. and then closing your eyes, and covering them with your hands, an exact delineation of the window remains for some time visible in the eye. This experiment requires a little practice to make it succeed well; since, if the eyes are fatigued by looking too long on the window, or the day be too bright, the luminous parts of the window will appear dark in the spectrum, and the dark parts of the frame-work will appear luminous, as in Exp. 2. Sect. III. And it is even difficult for many, who first try this experiment, to perceive the spectrum at all; for any hurry of mind, or even too great attention to the spectrum itself, will disappoint them, till they have had a little experience in attending to such small sensations. The spectra described in this section, termed direct ocular spectra, are produced without much fatigue of the eye; the irritation of the luminous object being soon withdrawn, or its quantity of light being not so great as to produce any degree of uneasiness in the organ of vision; which distinguishes them from the next class of ocular spectra, which are the consequence of fatigue. These direct spectra are best observed in such circumstances that no light, but what comes from the object, can fall upon the eye; as in looking through a tube, of half a yard long, and an inch wide, at a yellow paper on the side of a room, the direct spectrum was easily produced on closing the eye without taking it from the tube; but if the lateral light is admitted through the eyelids, or by throwing the spectrum on white paper, it becomes a reverse spectrum, as will be explained below. The other senses also retain for a time the impressions that have been made upon them, or the actions they have been excited into. So if a hard body is pressed upon the palm of the hand, as is practised in tricks of legerdemain, it is not easy to distinguish for a few seconds whether it remains or is removed; and tastes continue long to exist vividly in the mouth, as the smoke of tobacco, or the taste of gentian, after the sapid material is withdrawn. V. _A quantity of stimulus somewhat greater than the last mentioned excites the retina into spasmodic action, which ceases and recurs alternately._ 1. On looking for a time on the setting sun, so as not greatly to fatigue the sight, a yellow spectrum is seen when the eyes are closed and covered, which continues for a time, and then disappears and recurs repeatedly before it entirely vanishes. This yellow spectrum of the sun when the eyelids are opened becomes blue; and if it is made to fall on the green grass, or on other coloured objects, it varies its own colour by an intermixture of theirs, as will be explained in another place. 2. Place a lighted spermaceti candle in the night about one foot from your eye, and look steadily on the centre of the flame, till your eye becomes much more fatigued than in Sect. IV. Exp. 3.; and on closing your eyes a reddish spectrum will be perceived, which will cease and return alternately. The action of vomiting in like manner ceases, and is renewed by intervals, although the emetic drug is thrown up with the first effort: so after-pains continue some time after parturition; and the alternate pulsations of the heart of a viper are renewed for some time after it is cleared from its blood. VI. OF REVERSE OCULAR SPECTRA. _The retina, after having been excited into action by a stimulus somewhat greater them the last mentioned falls into opposite spasmodic action._ The actions of every part of animal bodies may be advantageously compared with each other. This strict analogy contributes much to the investigation of truth; while those looser analogies, which compare the phenomena of animal life with those of chemistry or mechanics, only serve to mislead our inquiries. When any of our larger muscles have been in long or in violent action, and their antagonists have been at the same time extended, as soon as the action of the former ceases, the limb is stretched the contrary way for our ease, and a pandiculation or yawning takes place. By the following observations it appears, that a similar circumstance obtains in the organ of vision; after it has been fatigued by one kind of action, it spontaneously falls into the opposite kind. 1. Place a piece of coloured silk, about an inch in diameter, on a sheet of white paper, about half a yard from your eyes; look steadily upon it for a minute; then remove your eyes upon another part of the white paper, and a spectrum will be seen of the form of the silk thus inspected, but of a colour opposite to it. A spectrum nearly similar will appear if the eyes are closed, and the eyelids shaded by approaching the hand near them, so as to permit some, but to prevent too much light falling on them. Red silk produced a green spectrum. Green produced a red one. Orange produced blue. Blue produced orange. Yellow produced violet. Violet produced yellow. That in these experiments the colours of the spectra are the reverse of the colours which occasioned them, may be seen by examining the third figure in Sir Isaac Newton's Optics, L. II. p. 1, where those thin laminæ of air, which reflected yellow, transmitted violet; those which reflected red, transmitted a blue green; and so of the rest, agreeing with the experiments above related. 2. These reverse spectra are similar to a colour, formed by a combination of all the primary colours except that with which the eye has been fatigued in making the experiment: thus the reverse spectrum of red must be such a green as would be produced by a combination of all the other prismatic colours. To evince this fact the following satisfactory experiment was made. The prismatic colours were laid on a circular pasteboard wheel, about four inches in diameter, in the proportions described in Dr. Priestley's History of Light and Colours, pl. 12. fig. 83. except that the red compartment was entirely left out, and the others proportionably extended so as to complete the circle. Then, as the orange is a mixture of red and yellow, and as the violet is a mixture of red and indigo, it became necessary to put yellow on the wheel instead of orange, and indigo instead of violet, that the experiment might more exactly quadrate with the theory it was designed to establish or confute; because in gaining a green spectrum from a red object, the eye is supposed to have become insensible to red light. This wheel, by means of an axis, was made to whirl like a top; and on its being put in motion, a green colour was produced, corresponding with great exactness to the reverse spectrum of red. 3. In contemplating any one or these reverse spectra in the closed and covered eye, it disappears and re-appears several times successively, till at length it entirely vanishes, like the direct spectra in Sect. V.; but with this additional circumstance, that when the spectrum becomes faint or evanescent, it is instantly revived by removing the hand from before the eyelids, so as to admit more light: because then not only the fatigued part of the retina is inclined spontaneously to fall into motions of a contrary direction, but being still sensible to all other rays of light, except that with which it was lately fatigued, is by these rays at the same time stimulated into those motions which form the reverse spectrum. From these experiments there is reason to conclude, that the fatigued part of the retina throws itself into a contrary mode of action, like oscitation or pandiculation, as soon as the stimulus which has fatigued it is withdrawn; and that it still remains sensible, that is, liable to be excited into action by any other colours at the same time, except the colour with which it has been fatigued. VII. _The retina after having been excited into action by a stimulus somewhat greater than the last mentioned falls into various successive spasmodic actions._ 1. On looking at the meridian sun as long as the eyes can well bear its brightness, the disk first becomes pale, with a luminous crescent, which seems to librate from one edge of it to the other, owing to the unsteadiness of the eye; then the whole phasis of the sun becomes blue, surrounded with a white halo; and on closing the eyes, and covering them with the hands, a yellow spectrum is seen, which in a little time changes into a blue one. M. de la Hire observed, after looking at the bright sun, that the impression in his eye first assumed a yellow appearance, and then green, and then blue; and wishes to ascribe these appearances to some affection of the nerves. (Porterfield on the Eye, Vol. I. p. 313.) 2. After looking steadily on about an inch square of pink silk, placed on white paper, in a bright sunshine, at the distance of a foot from my eyes, and closing and covering my eyelids, the spectrum of the silk was at first a dark green, and the spectrum of the white paper became of a pink. The spectra then both disappeared; and then the internal spectrum was blue; and then, after a second disappearance, became yellow, and lastly pink, whilst the spectrum of the field varied into red and green. These successions of different coloured spectra were not exactly the same in the different experiments, though observed, as near as could be, with the same quantity of light, and other similar circumstances; owing, I suppose, to trying too many experiments at a time; so that the eye was not quite free from the spectra of the colours which were previously attended to. The alternate exertions of the retina in the preceding section resembled the oscitation or pandiculation of the muscles, as they were performed in directions contrary to each other, and were the consequence of fatigue rather than of pain. And in this they differ from the successive dissimilar exertions of the retina, mentioned in this section, which resemble in miniature the more violent agitations of the limbs in convulsive diseases, as epilepsy, chorea S. Viti, and opisthotonos; all which diseases are perhaps, at first, the consequence of pain, and have their periods afterwards established by habit. VIII. _The retina, after having been excited into action by a stimulus somewhat greater than the last mentioned falls into a fixed spasmodic action, which continues for some days._ 1. After having looked long at the meridian sun, in making some of the preceding experiments, till the disks faded into a pale blue, I frequently observed a bright blue spectrum of the sun on other objects all the next and the succeeding day, which constantly occurred when I attended to it, and frequently when I did not previously attend to it. When I closed and covered my eyes, this appeared of a dull yellow; and at other times mixed with the colours of other objects on which it was thrown. It may be imagined, that this part of the retina was become insensible to white light, and thence a bluish spectrum became visible on all luminous objects; but as a yellowish spectrum was also seen in the closed and covered eye, there can remain no doubt of this being the spectrum of the sun. A similar appearance was observed by M. Æpinus, which he acknowledges he could give no account of. (Nov. Com. Petrop. V. 10. p. 2. and 6.) The locked jaw, and some cataleptic spasms, are resembled by this phenomenon; and from hence we may learn the danger to the eye by inspecting very luminous objects too long a time. IX. _A quantity of stimulus greater than the preceding induces a temporary paralysis of the organ of vision._ 1. Place a circular piece of bright red silk, about half an inch in diameter, on the middle of a sheet of white paper; lay them on the floor in a bright sunshine, and fixing your eyes steadily on the center of the red circle, for three or four minutes, at the distance of four or six feet from the object, the red silk will gradually become paler, and finally cease to appear red at all. 2. Similar to these are many other animal facts; as purges, opiates, and even poisons, and contagious matter, cease to stimulate our system, after we have been habituated to their use. So some people sleep undisturbed by a clock, or even by a forge hammer in their neighbourhood: and not only continued irritations, but violent exertions of any kind, are succeeded by temporary paralysis. The arm drops down after violent action, and continues for a time useless; and it is probable, that those who have perished suddenly in swimming, or in scating on the ice, have owed their deaths to the paralysis, or extreme fatigue, which succeeds every violent and continued exertion. X. MISCELLANEOUS REMARKS. There were some circumstances occurred in making these experiments, which were liable to alter the results of them, and which I shall here mention for the assistance of others, who may wish to repeat them. 1. _Of direct and inverse spectra existing at the same time_; _of reciprocal direct spectra_; _of a combination of direct and inverse spectra_; _of a spectral halo_; _rules to pre-determine the colours of spectra_. a. When an area, about six inches square, of bright pink Indian paper, had been viewed on an area, about a foot square, of white writing paper, the internal spectrum in the closed eye was green, being the reverse spectrum of the pink paper; and the external spectrum was pink, being the direct spectrum of the pink paper. The same circumstance happened when the internal area was white, and external one pink; that is, the internal spectrum was pink, and the external one green. All the same appearances occurred when the pink paper was laid on a black hat. b. When six inches square of deep violet polished paper was viewed on a foot square of white writing paper, the internal spectrum was yellow, being the reverse spectrum of the violet paper, and the external one was violet, being the direct spectrum of the violet paper. c. When six inches square of pink paper was viewed on a foot square of blue paper, the internal spectrum was blue, and the external spectrum was pink; that is, the internal one was the direct spectrum of the external object, and the external one was the direct spectrum of the internal object, instead of their being each the reverse spectrum of the objects they belonged to. d. When six inches square of blue paper were viewed on a foot square of yellow paper, the interior spectrum became a brilliant yellow, and the exterior one a brilliant blue. The vivacity of the spectra was owing to their being excited both by the stimulus of the interior and exterior objects; so that the interior yellow spectrum was both the reverse spectrum of the blue paper, and the direct one of the yellow paper; and the exterior blue spectrum was both the reverse spectrum of the yellow paper, and the direct one of the blue paper. e. When the internal area was only a square half-inch of red paper, laid on a square foot of dark violet paper, the internal spectrum was green, with a reddish-blue halo. When the red internal paper was two inches square, the internal spectrum was a deeper green, and the external one redder. When the internal paper was six inches square, the spectrum of it became blue, and the spectrum of the external paper was red. f. When a square half-inch of blue paper was laid on a six-inch square of yellow paper, the spectrum of the central paper in the closed eye was yellow, incircled with a blue halo. On looking long on the meridian sun, the disk fades into a pale blue surrounded with a whitish halo. These circumstances, though they very much perplexed the experiments till they were investigated, admit of a satisfactory explanation; for while the rays from the bright internal object in exp. a. fall with their full force on the center of the retina, and, by fatiguing that part of it, induce the reverse spectrum, many scattered rays, from the same internal pink paper, fall on the more external parts of the retina, but not in such quantity as to occasion much fatigue, and hence induce the direct spectrum of the pink colour in those parts of the eye. The same reverse and direct spectra occur from the violet paper in exp. b.: and in exp. c. the scattered rays from the central pink paper produce a direct spectrum of this colour on the external parts of the eye, while the scattered rays from the external blue paper produce a direct spectrum of that colour on the central part of the eye, instead of these parts of the retina falling reciprocally into their reverse spectra. In exp. d. the colours being the reverse of each other, the scattered rays from the exterior object falling on the central parts of the eye, and there exciting their direct spectrum, at the same time that the retina was excited into a reverse spectrum by the central object, and this direct and reverse spectrum being of similar colour, the superior brilliancy of this spectrum was produced. In exp. e. the effect of various quantities of stimulus on the retina, from the different respective sizes of the internal and external areas, induced a spectrum of the internal area in the center of the eye, combined of the reverse spectrum of that internal area and the direct one of the external area, in various shades of colour, from a pale green to a deep blue, with similar changes in the spectrum of the external area. For the same reasons, when an internal bright object was small, as in exp. f. instead of the whole of the spectrum of the external object being reverse to the colour of the internal object, only a kind of halo, or radiation of colour, similar to that of the internal object, was spread a little way on the external spectrum. For this internal blue area being so small, the scattered rays from it extended but a little way on the image of the external area of yellow paper, and could therefore produce only a blue halo round the yellow spectrum in the center. If any one should suspect that the scattered rays from the exterior coloured object do not intermix with the rays from the interior coloured object, and thus affect the central part of the eye, let him look through an opake tube, about two feet in length, and an inch in diameter, at a coloured wall of a room with one eye, and with the other eye naked; and he will find, that by shutting out the lateral light, the area of the wall seen through a tube appears as if illuminated by the sunshine, compared with the other parts of it; from whence arises the advantage of looking through a dark tube at distant paintings. Hence we may safely deduce the following rules to determine before-hand the colours of all spectra. 1. The direct spectrum without any lateral light is an evanescent representation of its object in the unfatigued eye. 2. With some lateral light it becomes of a colour combined of the direct spectrum of the central object, and of the circumjacent objects, in proportion to their respective quantity and brilliancy. 3. The reverse spectrum without lateral light is a representation in the fatigued eye of the form of its objects, with such a colour as would be produced by all the primary colours, except that of the object. 4. With lateral light the colour is compounded of the reverse spectrum of the central object, and the direct spectrum of the circumjacent objects, in proportion to their respective quantity and brilliancy. 2. _Variation and vivacity of the spectra occasioned by extraneous light._ The reverse spectrum, as has been before explained, is similar to a colour, formed by a combination of all the primary colours, except that with which the eye has been fatigued in making the experiment: so the reverse spectrum of red is such a green as would be produced by a combination of all the other prismatic colours. Now it must be observed, that this reverse spectrum of red is therefore the direct spectrum of a combination of all the other prismatic colours, except the red; whence, on removing the eye from a piece of red silk to a sheet of white paper, the green spectrum, which is perceived, may either be called the reverse spectrum of the red silk, or the direct spectrum of all the rays from the white paper, except the red; for in truth it is both. Hence we see the reason why it is not easy to gain a direct spectrum of any coloured object in the day-time, where there is much lateral light, except of very bright objects, as of the setting sun, or by looking through an opake tube; because the lateral external light falling also on the central part of the retina, contributes to induce the reverse spectrum, which is at the same time the direct spectrum of that lateral light, deducting only the colour of the central object which we have been viewing. And for the same reason, it is difficult to gain the reverse spectrum, where there is no lateral light to contribute to its formation. Thus, in looking through an opake tube on a yellow wall, and closing my eye, without admitting any lateral light, the spectra were all at first yellow; but at length changed into blue. And on looking in the same manner on red paper, I did at length get a green spectrum; but they were all at first red ones: and the same after looking at a candle in the night. The reverse spectrum was formed with greater facility when the eye was thrown from the object on a sheet of white paper, or when light was admitted through the closed eyelids; because not only the fatigued part of the retina was inclined spontaneously to fall into motions of a contrary direction; but being still sensible to all other rays of light except that with which it was lately fatigued, was by these rays stimulated at the same time into those motions which form the reverse spectrum. Hence, when, the reverse spectrum of any colour became faint, it was wonderfully revived by admitting more light through the eyelids, by removing the hand from before them: and hence, on covering the closed eyelids, the spectrum would often cease for a time, till the retina became sensible to the stimulus of the smaller quantity of light, and then it recurred. Nor was the spectrum only changed in vivacity, or in degree, by this admission of light through the eyelids; but it frequently happened, after having viewed bright objects, that the spectrum in the closed and covered eye was changed into a third spectrum, when light was admitted through the eyelids: which third spectrum was composed of such colours as could pass through the eyelids, except those of the object. Thus, when an area of half an inch diameter of pink paper was viewed on a sheet of white paper in the sunshine, the spectrum with closed and covered eyes was green; but on removing the hands from before the closed eyelids, the spectrum became yellow, and returned instantly again to green, as often as the hands were applied to cover the eyelids, or removed from them: for the retina being now insensible to red light, the yellow rays passing through the eyelids in greater quantity than the other colours, induced a yellow spectrum; whereas if the spectrum was thrown on white paper, with the eyes open, it became only a lighter green. Though a certain quantity of light facilitates the formation of the reverse spectrum, a greater quantity prevents its formation, as the more powerful stimulus excites even the fatigued parts of the eye into action; otherwise we should see the spectrum of the last viewed object as often as we turn our eyes. Hence the reverse spectra are best seen by gradually approaching the hand near the closed eyelids to a certain distance only, which must be varied with the brightness of the day, or the energy of the spectrum. Add to this, that all dark spectra, as black, blue, or green, if light be admitted through the eyelids, after they have been some time covered, give reddish spectra, for the reasons given in Sect. III. Exp. 1. From these circumstances of the extraneous light coinciding with the spontaneous efforts of the fatigued retina to produce a reverse spectrum, as was observed before, it is not easy to gain a direct spectrum, except of objects brighter than the ambient light; such as a candle in the night, the setting sun, or viewing a bright object through an opake tube; and then the reverse spectrum is instantaneously produced by the admission of some external light; and is as instantly converted again to the direct spectrum by the exclusion of it. Thus, on looking at the setting sun, on closing the eyes, and covering them, a yellow spectrum is seen, which is the direct spectrum of the setting sun; but on opening the eyes on the sky, the yellow spectrum is immediately changed into a blue one, which is the reverse spectrum of the yellow sun, or the direct spectrum of the blue sky, or a combination of both. And this is again transformed into a yellow one on closing the eyes, and so reciprocally, as quick as the motions of the opening and closing eyelids. Hence, when Mr. Melvill observed the scintillations of the star Sirius to be sometimes coloured, these were probably the direct spectrum of the blue sky on the parts of the retina fatigued by the white light of the star. (Essays Physical and Literary, p. 81. V. 2.) When a direct spectrum is thrown on colours darker than itself, it mixes with them; as the yellow spectrum of the setting sun, thrown on the green grass, becomes a greener yellow. But when a direct spectrum is thrown on colours brighter than itself, it becomes instantly changed into the reverse spectrum, which mixes with those brighter colours. So the yellow spectrum of the setting sun thrown on the luminous sky becomes blue, and changes with the colour or brightness of the clouds on which it appears. But the reverse spectrum mixes with every kind of colour on which it is thrown, whether brighter than itself or not; thus the reverse spectrum, obtained by viewing a piece of yellow silk, when thrown on white paper, was a lucid blue green; when thrown on black Turkey leather, becomes a deep violet. And the spectrum of blue silk, thrown on white paper, was a light yellow; on black silk was an obscure orange; and, the blue spectrum, obtained from orange-coloured silk, thrown on yellow, became a green. In these cases the retina is thrown into activity or sensation by the stimulus of external colours, at the same time that it continues the activity or sensation which forms the spectra; in the same manner as the prismatic colours, painted on a whirling top, are seen to mix together. When these colours of external objects are brighter than the direct spectrum which is thrown upon them, they change it into the reverse spectrum, like the admission of external light on a direct spectrum, as explained above. When they are darker than the direct spectrum, they mix with it, their weaker stimulus being inefficient to induce the reverse spectrum. 3. _Variation of spectra in respect to number, and figure, and remission._ [Illustration: Fig. 4.] When we look long and attentively at any object, the eye cannot always be kept entirely motionless; hence, on inspecting a circular area of red silk placed on white paper, a lucid crescent or edge is seen to librate on one side or other of the red circle: for the exterior parts of the retina sometimes falling on the edge of the central silk, and sometimes on the white paper, are less fatigued with red light than the central part of the retina, which is constantly, exposed to it; and therefore, when they fall on the edge of the red silk, they perceive it more vividly. Afterwards, when the eye becomes fatigued, a green spectrum in the form of a crescent is seen to librate on one side or other of the central circle, as by the unsteadiness of the eye a part of the fatigued retina falls on the white paper; and as by the increasing fatigue of the eye the central part of the silk appears paler, the edge on which the unfatigued part of the retina occasionally falls will appear of a deeper red than the original silk, because it is compared with the pale internal part of it. M. de Buffon in making this experiment observed, that the red edge of the silk was not only deeper coloured than the original silk; but, on his retreating a little from it, it became oblong, and at length divided into two, which must have been owing to his observing it either before or behind the point of intersection of the two optic axises. Thus, if a pen is held up before a distant candle, when we look intensely at the pen two candles are seen behind it; when we look intensely at the candle two pens are seen. If the sight be unsteady at the time of beholding the sun, even though one eye only be used, many images of the sun will appear, or luminous lines, when the eye is closed. And as some parts of these will be more vivid than others, and some parts of them will be produced nearer the center of the eye than others, these will disappear sooner than the others; and hence the number and shape of these spectra of the sun will continually vary, as long as they exist. The cause of some being more vivid than others, is the unsteadiness of the eye of the beholder, so that some parts of the retina have been longer exposed to the sunbeams. That some parts of a complicated spectrum fade and return before other parts of it, the following experiment evinces. Draw three concentric circles; the external one an inch and a half in diameter, the middle one an inch, and the internal one half an inch; colour the external and internal areas blue, and the remaining one yellow, as in Fig. 4.; after having looked about a minute on the center of these circles, in a bright light, the spectrum of the external area appears first in the closed eye, then the middle area, and lastly the central one; and then the central one disappears, and the others in inverted order. If concentric circles of more colours are added, it produces the beautiful ever changing spectrum in Sect. I. Exp. 2. From hence it would seem, that the center of the eye produces quicker remissions of spectra, owing perhaps to its greater sensibility; that is, to its more energetic exertions. These remissions of spectra bear some analogy to the tremors of the hands, and palpitations of the heart, of weak people: and perhaps a criterion of the strength of any muscle or nerve may be taken from the time it can be continued in exertion. 4. _Variation of spectra in respect to brilliancy; the visibility of the circulation of the blood in the eye._ 1. The meridian or evening light makes a difference in the colours of some spectra; for as the sun descends, the red rays, which are less refrangible by the convex atmosphere, abound in great quantity. Whence the spectrum of the light parts of a window at this time, or early in the morning, is red; and becomes blue either a little later or earlier; and white in the meridian day; and is also variable from the colour of the clouds or sky which are opposed to the window. 2. All these experiments are liable to be confounded, if they are made too soon after each other, as the remaining spectrum will mix with the new ones. This is a very troublesome circumstance to painters, who are obliged to look long upon the same colour; and in particular to those whose eyes, from natural debility, cannot long, continue the same kind of exertion. For the same reason, in making these experiments, the result becomes much varied if the eyes, after viewing any object, are removed on other objects for but an instant of time, before we close them to view the spectrum; for the light from the object, of which we had only a transient view, in the very time of closing our eyes acts as a stimulus on the fatigued retina; and for a time prevents the defined spectrum from appearing, or mixes its own spectrum with it. Whence, after the eyelids are closed, either a dark field, or some unexpected colours, are beheld for a few seconds, before the desired spectrum becomes distinctly visible. 3. The length of time taken up in viewing an object, of which we are to observe the spectrum, makes a great difference in the appearance of the spectrum, not only in its vivacity, but in its colour; as the direct spectrum of the central object, or of the circumjacent ones, and also the reverse spectra of both, with their various combinations, as well as the time of their duration in the eye, and of their remissions or alternations, depend upon the degree of fatigue the retina is subjected to. The Chevalier d'Arcy constructed a machine by which a coal of fire was whirled round in the dark, and found, that when a luminous body made a revolution in eight thirds of time, it presented to the eye a complete circle of fire; from whence he concludes, that the impression continues on the organ about the seventh part of a second. (Mem. de l'Acad. des Sc. 1765.) This, however, is only to be considered as the shortest time of the duration of these direct spectra; since in the fatigued eye both the direct and reverse spectra, with their intermissions, appear to take up many seconds of time, and seem very variable in proportion to the circumstances of fatigue or energy. 4. It sometimes happens, if the eyeballs have been rubbed hard with the fingers, that lucid sparks are seen in quick motion amidst the spectrum we are attending to. This is similar to the flashes of fire from a stroke on the eye in fighting, and is resembled by the warmth and glow, which appears upon the skin after friction, and is probably owing to an acceleration of the arterial blood into the vessels emptied by the previous pressure. By being accustomed to observe such small sensations in the eye, it is easy to see the circulation of the blood in this organ. I have attended to this frequently, when I have observed my eyes more than commonly sensible to other spectra. The circulation may be seen either in both eyes at a time, or only in one of them; for as a certain quantity of light is necessary to produce this curious phenomenon, if one hand be brought nearer the closed eyelids than the other, the circulation in that eye will for a time disappear. For the easier viewing the circulation, it is sometimes necessary to rub the eyes with a certain degree of force after they are closed, and to hold the breath rather longer than is agreeable, which, by accumulating more blood in the eye, facilitates the experiment; but in general it may be seen distinctly after having examined other spectra with your back to the light, till the eyes become weary; then having covered your closed eyelids for half a minute, till the spectrum is faded away which you were examining, turn your face to the light, and removing your hands from the eyelids, by and by again shade them a little, and the circulation becomes curiously distinct. The streams of blood are however generally seen to unite, which shews it to be the venous circulation, owing, I suppose, to the greater opacity of the colour of the blood in these vessels; for this venous circulation is also much more easily seen by the microscope in the tail of a tadpole. 5. _Variation of spectra in respect to distinctness and size; with a new way of magnifying objects._ 1. It was before observed, that when the two colours viewed together were opposite to each other, as yellow and blue, red and green, &c. according to the table of reflections and transmissions of light in Sir Isaac Newton's Optics, B. II. Fig. 3. the spectra of those colours were of all others the most brilliant, and best defined; because they were combined of the reverse spectrum of one colour, and of the direct spectrum of the other. Hence, in books printed with small types, or in the minute graduation of thermometers, or of clock-faces, which are to be seen at a distance, if the letters or figures are coloured with orange, and the ground with indigo; or the letters with red, and the ground with green; or any other lucid colour is used for the letters, the spectrum of which is similar to the colour of the ground; such letters will be seen much more distinctly, and with less confusion, than in black or white: for as the spectrum of the letter is the same colour with the ground on which they are seen, the unsteadiness of the eye in long attending to them will not produce coloured lines by the edges of the letters, which is the principal cause of their confusion. The beauty of colours lying in vicinity to each other, whose spectra are thus reciprocally similar to each colour, is owing to this greater ease that the eye experiences in beholding them distinctly; and it is probable, in the organ of hearing, a similar circumstance may constitute the pleasure of melody. Sir Isaac Newton observes, that gold and indigo were agreeable when viewed together; and thinks there may be some analogy between the sensations of light and sound. (Optics, Qu. 14.) In viewing the spectra of bright objects, as of an area of red silk of half an inch diameter on white paper, it is easy to magnify it to tenfold its size: for if, when the spectrum is formed, you still keep your eye fixed on the silk area, and remove it a few inches further from you, a green circle is seen round the red silk: for the angle now subtended by the silk is less than it was when the spectrum was formed, but that of the spectrum continues the same, and our imagination places them at the same distance. Thus when you view a spectrum on a sheet of white paper, if you approach the paper to the eye, you may diminish it to a point; and if the paper is made to recede from the eye, the spectrum will appear magnified in proportion to the distance. [Illustration: Fig. 5.] I was surprised, and agreeably amused, with the following experiment. I covered a paper about four inches square with yellow, and with a pen filled with a blue colour wrote upon the middle of it the word BANKS in capitals, as in Fig. 5, and sitting with my back to the sun, fixed my eyes for a minute exactly on the center of the letter N in the middle of the word; after closing my eyes, and shading them somewhat with my hand, the word was distinctly seen in the spectrum in yellow letters on a blue field; and then, on opening my eyes on a yellowish wall at twenty feet distance, the magnified name of BANKS appeared written on the wall in golden characters. _Conclusion._ It was observed by the learned M. Sauvage (Nosol. Method. Cl. VIII. Ord. i.) that the pulsations of the optic artery might be perceived by looking attentively on a white wall well illuminated. A kind of net-work, darker than the other parts of the wall, appears and vanishes alternately with every pulsation. This change of the colour of the wall he well ascribes to the compression of the retina by the diastole of the artery. The various colours produced in the eye by the pressure of the finger, or by a stroke on it, as mentioned by Sir Isaac Newton, seem likewise to originate from the unequal pressure on various parts of the retina. Now as Sir Isaac Newton has shewn, that all the different colours are reflected or transmitted by the laminæ of soap bubbles, or of air, according to their different thickness or thinness, is it not probable, that the effect of the activity of the retina may be to alter its thickness or thinness, so as better to adapt it to reflect or transmit the colours which stimulate it into action? May not muscular fibres exist in the retina for this purpose, which may be less minute than the locomotive muscles of microscopic animals? May not these muscular actions of the retina constitute the sensation of light and colours; and the voluntary repetitions of them, when the object is withdrawn, constitute our memory of them? And lastly, may not the laws of the sensations of light, here investigated, be applicable to all our other senses, and much contribute to elucidate many phenomena of animal bodies both in their healthy and diseased state; and thus render this investigation well worthy the attention of the physician, the metaphysician, and the natural philosopher? November 1, 1785. * * * * * Dum, Liber! astra petis volitans trepidantibus alis, Irruis immemori, parvula gutta, mari. Me quoque, me currente rotâ revolubilis ætas Volverit in tenebras,--i, Liber, ipse sequor. * * * * * INDEX TO THE SECTIONS OF PART FIRST. A. Abortion from fear, xxxix. 6. 5. Absorbent vessels, xxiii. 3. xxix. 1. ---- regurgitate their fluids, xxix. 2. ---- their valves, xxix. 2. ---- communicate with vena portarum, xxvii. 2. Absorption of solids, xxxiii. 3. 1. xxxvii. ---- of fluids in anasarca, xxxv. 1. 3. Accumulation of sensorial power, iv. 2. xii. 5. 2. Activity of system too great, cure of, xii. 6. ---- too small, cure of, xii. 7. Age, old, xii. 3. 1. xxxvii. 4. Ague-fit, xii. 7. 1. xxxii. 3. 4. xxxii. 9. ---- how cured by bark, xii. 3. 4. ---- periods, how occasioned, xii. 2. 3. xxxii. 3. 4. Ague cakes, xxxii. 7. xxxii. 9. Air, sense of fresh, xiv. 8. ---- injures ulcers, xxviii. 2. ---- injected into veins, xxxii. 5. Alcohol deleterious, xxx. 3. Alliterations, why agreeable, xxii. 2. Aloes in lessened doses, xii. 3. 1. American natives indolent, xxxi. 2. ---- narrow shouldered, xxxi. 1. Analogy intuitive, xvii. 3. 7. Animals less liable to madness, xxxiii. 1. ---- less liable to contagion, xxxiii. 1. ---- how to teach, xxii. 3. 2. ---- their similarity to each other, xxxix. 4. 8. ---- their changes after nativity, xxxix. 4. 8. ---- their changes before nativity, xxxix. 4. 8. ---- less liable to contagious diseases, why, xxxiii. 1. 5. ---- less liable to delirium and insanity, why, xxxiii. 1. 5. ---- easier to preserve than to reproduce, xxxvii. ---- food, distaste of, xxviii. 1. ---- appetency, xxxix. 4. 7. Antipathy, x. 2. 2. Aphthæ, xxviii. Apoplexy, xxxiv. 1. 7. ---- not from deficient irritation, xxxii. 2. 1. Appetites, xi. 2. 2. xiv. 8. Architecture, xxii. 2. xvi. 10. Arts, fine, xxii. 2. Asparagus, its smell in urine, xxix. Association defined, ii. 2. 11. iv. 7. v. 2. ---- associate motions, x. ---- stronger than irritative ones, xxiv. 2. 8. ---- formed before nativity, xi. 3. ---- with irritative ones, xxiv. 2. 8. ---- with retrograde ones, xxv. 7. xxv. 10. xxv. 15. ---- diseases from, xxxv. Asthma, xviii. 15. Attention, language of, xvi. 8. 6. Atrophy, xxviii. Aversion, origin of, xi. 2. 3. B. Balance ourselves by vision, xx. 1. Bandage increases absorption, xxxiii. 3. 2. Barrenness, xxxvi. 2. 3. Battement of sounds, xx. 7. Bath, cold. See Cold Bath. Beauty, sense of, xvi. 6. xxii. 2. Bile-ducts, xxx. ---- stones, xxx. 1. 3. ---- regurgitates into the blood, xxiv. 2. 7. ---- vomiting of, xxx. 1. 3. Birds of passage, xvi. 12. ---- nests of, xvi. 13. ---- colour of their eggs, xxxix. 5. Biting in pain, xxxiv. 1. 3. ---- of mad animals, xxxiv. 1. 3. Black spots on dice appear red, xl. 3. Bladder, communication of with the intestines, xxix. 3. ---- of fish, xxiv. 1. 4. Blood, transfusion of in nervous fevers, xxxii. 4. ---- deficiency of, xxxii. 2. and 4. ---- from the vena portarum into the intestines, xxvii. 2. ---- its momentum, xxxii. 5. 2. ---- momentum increased by venesection, xxxii. 5. 4. ---- drawn in nervous pains, xxxii. 5. 4. ---- its oxygenation, xxxviii. Breasts of men, xiv. 8. Breathing, how learnt, xvi. 4. Brutes differ from men, xi. 2. 3. xvi. 17. Brutes. See Animals. Buxton bath, why it feels warm, xii. 2. 1. xxxii. 3. 3. C. Capillary vessels are glands, xxvi. 1. Catalepsy, xxxiv. 1. 5. Catarrh from cold skin, xxxv. 1. 3. xxxv. 2. 3. ---- from thin caps in sleep, xviii. 15. Catenation of motions defined, ii. 2. 11. iv. 7. ---- cause of them, xvii. 1. 3. ---- described, xvii. ---- continue some time after their production, xvii. 1. 3. ---- voluntary ones dissevered in sleep, xvii. 1. 12. xvii. 3. 7. Cathartics, external, their operation, xxix. 7. 6. Causation, animal, defined, ii. 2. 11. iv. 7. Cause of causes, xxxix. 4. 8. Causes inert and efficient, xxxix. 8. 2. ---- active and passive, xxxix. 8. 3. ---- proximate and remote, xxxix. 8. 4. Chick in the egg, oxygenation of, xxxviii. 2. Child riding on a stick, xxxiv. 2. 6. Chilness after meals, xxi. 3. xxxv. 1. 1. Cholera, case of, xxv. 13. Circulation in the eye visible, xl. 10. 4. Cold in the head, xii. 6. 5. ---- perceived by the teeth, xxxii. 3. 1. xiv. 6. ---- air, uses of in fevers, xxxii. 3. 3. ---- feet, produces coryza, xxxv. 2. 3. xxxv. 1. 3. ---- bath, why it strengthens, xxxii. 3. 2. ---- short and cold breathing in it, xxxii. 3. 2. ---- produces a fever-fit, xxxii. 3. 2. ---- fit of fever the consequence of hot fit, xxxii. 9. 3. ---- bathing in pulmonary hæmorrhage, xxvii. 1. ---- fits of fever, xxxii. 4. xxxii. 9. xvii. 3. 3. Colours of animals, efficient cause of, xxxix. 5. 1. ---- of eggs from female imagination, xxxix. 5. 1. ---- of the choroid coat of the eye, xxxix. 5. 1. ---- of birds nests, xvi. 13. Comparing ideas, xv. 3. Consciousness, xv. 3. 4. ---- in dreams, xviii. 13. Consent of parts. See Sympathy. Consumption, its temperament, xxxi. 1. and 2. ---- of dark-eyed patients, xxvii. 2. ---- of light-eyed patients, xxviii. 2. ---- is contagious, xxxiii. 2. 7. Contagion, xii. 3. 6. xix. 9. xxxiii. 2. 6. and 8. xxii. 3. 3. ---- does not enter the blood, xxxiii. 2. 10. xxii. 3. 3. Contraction and attraction, iv. 1. ---- of fibres produces sensation, iv. 5. xii. 1. 6. ---- continues some time, xii. 1. 5. ---- alternates with relaxation, xii. 1. 3. Convulsion, xvii. 1. 8. xxxiv. 1. 1. and 4. iii. 5. 8. ---- of particular muscles, xvii. 1. 8. ---- periods of, xxxvi. 3. 9. Coryza. See Catarrh. Cough, nervous, periods of, xxxvi. 3. 9. Cramp, xviii. 15. xxxiv. 1. 7. Critical days from lunations, xxxvi. 4. D. Darkish room, why we see well in it, xii. 2. 1. Debility sensorial and stimulatory, xii. 2. 1. ---- direct and indirect of Dr. Brown, xii. 2. 1. xxxii. 3. 2. ---- See Weakness. ---- from drinking spirits, cure of, xii. 7. 8. ---- in fevers, cure of, xii. 7. 8. Deliberation, what, xxxiv. 1. Delirium, two kinds of, xxxiii. 1. 4. xxxiv. 2. 2. ---- cases of, iii. 5. 8. ---- prevented by dreams, xviii. 2. Desire, origin of, xi. 2. 3. Diabetes explained, xxix. 4. ---- with bloody urine, xxvii. 2. ---- in the night, xviii. 15. Diarrhoea, xxix. 4. Digestion, xxxiii. 1. xxxvii. ---- strengthened by emetics, xxxv. 1. 3. ---- strengthened by regular hours, why, xxxvi. 2. 1. Digitalis, use of in dropsy, xxix. 5. 2. Distention acts as a stimulus, xxxii. 4. ---- See Extension. Distinguishing, xv. 3. Diurnal circle of actions, xxv. 4. Doubting, xv. 3. Dreams, viii. 1. 2. xiv. 2. 5. ---- their inconsistency, xviii. 17. ---- no surprise in them, xviii. 17. ---- much novelty of combination, xviii. 9. Dropsies explained, xxix. 5. 1. Dropsy cured by insanity, xxxiv. 2. 7. ---- cure of, xxix. 5. 2. Drunkards weak till next day, xvii. 1. 7. ---- stammer, and stagger, and weep, xii. 4. 1. xxi. 4. ---- see objects double, why, xxi. 7. ---- become delirious, sleepy, stupid, xxi. 5. Drunkenness. See Intoxication, xxi. ---- diminished by attention, xxi. 8. Dyspnoea in cold bath, xxxii. 3. 2. E. Ear, a good one, xvi. 10. ---- noise in, xx. 7. Eggs of frogs, fish, fowl, xxxix. 2. ---- of birds, why spotted, xxxix. 5. ---- with double yolk, xxxix. 4. 4. Electricity, xii. 1. xiv. 9. ---- jaundice cured by it, xxx. 1. 2. Embryon produced by the male, xxxix. 2. ---- consists of a living fibre, xxxix. 4. ---- absorbs nutriment, receives oxygen, xxxix. 1. ---- its actions and sensations, xvi. 2. Emetic. See Vomiting. Emotions, xi. 2. 2. Ennui, or tædium vitæ, xxxiv. 2. 3. xxxiii. 1. 1. xxxix. 6. Epileptic fits explained, xxxiv. 1. 4. xxvii. 2. ---- in sleep, why, xviii. 14. & 15. Equinoxial lunations, xxxii. 6. Excitability perpetually varies, xii. 1. 7. ---- synonymous to quantity of sensorial power, xii. 1. 7. Exercise, its use, xxxii. 5. 3. Exertion of sensorial power defined, xii. 2. 1. Existence in space, xiv. 2. 5. Extension, sense of, xiv. 7. Eyes become black in some epilepsies, xxvii. 2. F. Face, flushing of after dinner, xxxv. 1. 1. ---- why first affected in small-pox, xxxv. 1. 1. ---- red from inflamed liver, xxxv. 2. 2. Fainting fits, xii. 7. 1. xiv. 7. Fear, language of, xvi. 8. 1. ---- a cause of fever, xxxii. 8. ---- cause of, xvii. 3. 7. Fetus. See Embryon, xvi. 2. xxxix. 1. Fevers, irritative, xxxii. 1. ---- intermittent, xxxii. 1. xxxii. 3. ---- sensitive, xxxiii. 1. ---- not an effort of nature for relief, xxxii. 10. ---- paroxysms of, xii. 7. 1. xii. 2. 3. xii. 3. 5. ---- why some intermit and not others, xxxvi. 1. ---- cold fits of, xxxii. 4. xxxii. 9. xvii. 3. 3. ---- periods of, xxxvi. 3. ---- have solar or lunar periods, xxxii. 6. ---- source of the symptoms of, xxxii. 1. ---- prostration of strength in, xii. 4. 1. xxxii. 3. 2. ---- cure of, xii. 6. 1. ---- how cured by the bark, xii. 3. 4. ---- cured by increased volition, xii. 2. 4. xxxiv. 2. 8. ---- best quantity of stimulus in, xii. 7. 8. Fibres. See Muscles. Fibres, their mobility, xii. 1. 7. xii. 1. 1. ---- contractions of, vi. xii. 1. 1. ---- four classes of their motions, vi. ---- their motions distinguished from sensorial ones, v. 3. Figure, xiv. 2. 2. iii. 1. Fish, their knowledge, xvi. 14. Foxglove, its use in dropsies, xxix. 5. 2. ---- overdose of, xxv. 17. Free-will, xv. 3. 7. G. Gall-stone, xxv. 17. ---- See Bile-stones. Generation, xxxiii. 1. xxxix. Gills of fish, xxxviii. 2. Glands, xxiii. 2. ---- conglobate glands, xxiii. 3. ---- have their peculiar stimulus, xi. 1. ---- their senses, xiv. 9. xxxix. 6. ---- invert their motions, xxv. 7. ---- increase their motions, xxv. 7. Golden rule for exhibiting wine, xii. 7. 8. ---- for leaving off wine, xii. 7. 8. Gout from inflamed liver, xxxv. 2. 2. xviii. 16. xxiv. 2. 8. ---- in the stomach, xxiv. 2. 8. xxv. 17. ---- why it returns after evacuations, xxxii. 4. ---- owing to vinous spirit only, xxi. 10. ---- periods of, xxxvi. 3. 6. Grinning in pain, xxxiv. 1. 3. Gyration on one foot, xx. 5. and 6. H. Habit defined, ii. 2. 11. iv. 7. Hæmorrhages, periods of, xxxvi. 3. 11. ---- from paralysis of veins, xxvii. 1. and 2. Hair and nails, xxxix. 3. 2. ---- colour of, xxxix. 5. 1. Harmony, xxii. 2. Head-achs, xxxv. 2. 1. Hearing, xiv. 4. Heat, sense of, xiv. 6. xxxii. 3. 1. ---- produced by the glands, xxxii. 3. ---- external and internal, xxxii. 3. 1. ---- atmosphere of heat, xxxii. 3. 1. ---- increases during sleep, xviii. 15. Hemicrania, xxxv. 2. 1. ---- from decaying teeth, xxxv. 2. 1. Hepatitis, cause of, xxxv. 2. 3. Hereditary diseases, xxxix. 7. 6. Hermaphrodite insects, xxxix. 5. Herpes, xxviii. 2. ---- from inflamed kidney, xxxv. 2. 2. Hilarity from diurnal fever, xxxvi. 3. 1. Hunger, sense of, xiv. 8. Hydrophobia, xxii. 3. 3. Hypochondriacism, xxxiii. 1. 1. xxxiv. 2. 3. I. Ideas defined, ii. 2. 7. ---- are motions of the organs of sense, iii. 4. xviii. 5. xviii. 10. xviii. 6. ---- analogous to muscular motions, iii. 5. ---- continue some time, xx. 6. ---- new ones cannot be invented, iii. 6. 1. ---- abstracted ones, iii. 6. 4. ---- inconsistent trains of, xviii. 17. ---- perish with the organ of sense, iii. 4. 4. ---- painful from inflammation of the organ, iii. 5. 5. ---- irritative ones, vii. 1. 4. vii. 3. 2. xv. 2. xx. 7. ---- of resemblance, contiguity, causation, viii. 3. 2. x. 3. 3. ---- resemble the figure and other properties of bodies, xiv. 2. 2. ---- received in tribes, xv. 1. ---- of the same sense easier combined, xv. 1. 1. ---- of reflection, xv. 1. 6. ii. 2. 12. Ideal presence, xv. 1. 7. Identity, xv. 3. 5. xviii. 13. Iliac passion, xxv. 15. Imagination, viii. 1. 2. xv. 1. 7. xv. 2. 2. ---- of the male forms the sex, xxxix. 6. Imitation, origin of, xii. 3. 3. xxxix. 5. xxii. 3. xvi. 7. Immaterial beings, xiv. 1. xiv. 2. 4. Impediment of speech, xvii. 1. 10. xvii. 2. 10. Infection. See Contagion. Inflammation, xii. 2. 3. xxxiii. 2. 2. ---- great vascular exertion in, xii. 2. 1. ---- not from pains from defect of stimulus, xxxiii. 2. 3. ---- of parts previously insensible, xii. 3. 7. ---- often distant from its cause, xxiv. 2. 8. ---- observes solar days, xxxii. 6. ---- of the eye, xxxiii. 3. 1. ---- of the bowels prevented by their continued action in sleep, xviii. 2. Inoculation with blood, xxxiii. 2. 10. Insane people, their great strength, xii. 2. 1. Insanity (see Madness) pleasurable one, xxxiv. 2. 6. Insects, their knowledge, xvi. 15. and 16. ---- in the heads of calves, xxxix. 1. ---- class of, xxxix. 4. 8. Instinctive actions defined, xvi. 1. Intestines, xxv. 3. Intoxication relieves pain, why, xxi. 3. ---- from food after fatigue, xxi. 2. ---- diseases from it, xxi. 10. ---- See Drunkenness. Intuitive analogy, xvii. 3. 7. Invention, xv. 3. 3. Irritability increases during sleep, xviii. 15. Itching, xiv. 9. J. Jaundice from paralysis of the liver, xxx. 1. 2. ---- cured by electricity, xxx. 1. 2. Jaw-locked, xxxiv. 1. 5. Judgment, xv. 3. K. Knowledge of various animals, xvi. 11. L. Lachrymal sack, xvi. 8. xxiv. 2. 2. and 7. Lacteals, paralysis of, xxviii. ---- See Absorbents. Lady playing on the harpsichord, xvii. 2. ---- distressed for her dying bird, xvii. 2. 10. Language, natural, its origin, xvi. 7. & 8. ---- of various passions described, xvi. 8. ---- artificial, of various animals, xvi. 9. ---- theory of, xxxix. 8. 3. Lapping of puppies, xvi. 4. Laughter explained, xxxiv. 1. 4. ---- from tickling, xvii. 3. 5. xxxiv. 1. 4. ---- from frivolous ideas, xxxiv. 1. 4. xviii. 12. Life, long, art of producing, xxxvii. Light has no momentum, iii. 3. 1. Liquor amnii, xvi. 2. xxxviii. 2. ---- is nutritious, xxxviii. 3. ---- frozen, xxxviii. 3. Liver, paralysis of, xxx. 1. 4. ---- large of geese, xxx. 1. 6. Love, sentimental, its origin, xvi. 6. ---- animal, xiv. 8. xvi. 5. Lunar periods affect diseases, xxxii. 6. Lust, xiv. 8. xvi. 5. Lymphatics, paralysis of, xxviii. ---- See Absorbents. M. Mad-dog, bite of, xxii. 3. 3. Madness, xxxiv. 2. 1. xii. 2. 1. Magnetism, xii. 1. 1. Magnifying objects, new way of, xl. 10. 5. Male animals have teats, xxxix. 4. 8. ---- pigeons give milk, xxxix. 4. 8. Man distinguished from brutes, xi. 2. 3. xvi. 17. Material world, xiv. 1. xiv. 2. 5. xviii. 7. Matter, penetrability of, xiv. 2. 3. ---- purulent, xxxiii. 2. 4. Measles, xxxiii. 2. 9. Membranes, xxvi. 2. Memory defined, ii. 2. 10. xv. 1. 7. xv. 3. Menstruation by lunar periods, xxxii. 6. Miscarriage from fear, xxxix. 6. 5. Mobility of fibres, xii. 1. 7. Momentum of the blood, xxxii. 5. 2. ---- sometimes increased by venesection, xxxii. 5. 4. Monsters, xxxix. 4. 4. and 5. 2. ---- without heads, xxxviii. 3. Moon and sun, their influence, xxxii. 6. Mortification, xxxiii. 3. 3. Motion is either cause or effect, i. xiv. 2. 2. ---- primary and secondary, i. ---- animal, i. iii. 1. ---- propensity to, xxii. 1. ---- animal, continue some time after their production, xvii. 1. 3. ---- defined, a variation of figure, iii. 1. xiv. 2. 2. xxxix. 8. Mucus, experiments on, xxvi. 1. ---- secretion of, xxvi. 2. Mules, xxxix. 4. 5. and 6. xxxix. 5. 2. Mule plants, xxxix. 2. Muscæ volitantes, xl. 2. Muscles constitute an organ of sense, xiv. 7. ii. 2. 4. ---- stimulated by extension, xi. 1. xiv. 7. ---- contract by spirit of animation, xii. 1. 1. and 3. Music, xvi. 10. xxii. 2. Musical time, why agreeable, xii. 3. 3. N. Nausea, xxv. 6. Nerves and brain, ii. 2. 3. ---- extremities of form the whole system, xxxvii. 3. ---- are not changed with age, xxxvii. 4. Nervous pains defined, xxxiv. 1. 1. Number defined, xiv. 2. 2. Nutriment for the embryon, xxxix. 5. 2. Nutrition owing to stimulus, xxxvii. 3. ---- by animal selection, xxxvii. 3. ---- when the fibres are elongated, xxxvii. 3. ---- like inflammation, xxxvii. 3. O. Objects long viewed become faint, iii. 3. 2. Ocular spectra, xl. Oil externally in diabætes, xxix. 4. Old age from inirritability, xxxvii. Opium is stimulant, xxxii. 2. 2. ---- promotes absorption after evacuation, xxxiii. 3. 1. ---- in increasing doses, xii. 3. 1. Organs of sense, ii. 2. 5. and 6. Organs when destroyed cease to produce ideas, iii. 4. 4. Organic particles of Buffon, xxxvii. 3. xxxix. 3. 3. Organ-pipes, xx. 7. Oxygenation of the blood, xxxviii. P. Pain from excess and defect of motion, iv. 5. xii. 5. 3. xxxiv. 1. xxxv. 2. 1. ---- not felt during exertion, xxxiv. 1. 2. ---- from greater contraction of fibres, xii. 1. 6. ---- from accumulation of sensorial power, xii. 5. 3. ---- from light, pressure, heat, caustics, xiv. 9. ---- in epilepsy, xxxv. 2. 1. ---- distant from its cause, xxiv. 2. 8. ---- from stone in the bladder, xxxv. 2. 1. ---- of head and back from defect, xxxii. 3. ---- from a gall-stone, xxxv. 2. 1. xxv. 17. ---- of the stomach in gout, xxv. 17. ---- of shoulder in hepatitis, xxxv. 2. 4. ---- produces volition, iv. 6. Paleness in cold fit, xxxii. 3. 2. Palsies explained, xxxiv. 1. 7. Paralytic limbs stretch from irritation, vii. 1. 3. ---- patients move their sound limb much, xii. 5. 1. Paralysis from great exertion, xii. 4. 6. ---- from less exertion, xii. 5. 6. ---- of the lacteals, xxviii. ---- of the liver, xxx. 1. 4. ---- of the right arm, why, xxxiv. 1. 7. ---- of the veins, xxvii. 2. Particles of matter will not approach, xii. 1. 1. Passions, xi. 2. 2. ---- connate, xvi. 1. Pecking of chickens, xvi. 4. Perception defined, ii. 2. 8. xv. 3. 1. Periods of agues, how formed, xxxii. 3. 4. ---- of diseases, xxxvi. ---- of natural actions and of diseased actions, xxxvi. Perspiration in fever-fits, xxxii. 9. See Sweat. Petechiæ, xxvii. 2. Pigeons secrete milk in their stomachs, xxxix. 4. 8. Piles, xxvii. 2. Placenta a pulmonary organ, xxxviii. 2. Pleasure of life, xxxiii. 1. xxxix. 5. ---- from greater fibrous contractions, xii. 1. 6. ---- what kind causes laughter, xxxiv. 1. 4. ---- what kind causes sleep, xxxiv. 1. 4. Pleurisy, periods of, xxxvi. 3. 7. ---- cause of, xxxv. 2. 3. Prometheus, story of, xxx. 3. Prostration of strength in fevers, xii. 4. 1. Pupils of the eyes large, xxxi. 1. Pulse quick in fevers with debility, xii. 1. 4. xii. 5. 4. xxxii. 2. 1. ---- in fevers with strength, xxxii. 2. ---- from defect of blood, xxxii. 2. 3. xii. 1. 4. ---- weak from emetics, xxv. 17. Q. Quack advertisements injurious. Preface. Quadrupeds have no sanguiferous lochia, xxxviii. 2. ---- have nothing similar to the yolk of egg, xxxix. 1. R. Rhaphania, periods of, xxxvi. 3. 9. Reason, ix. 1. 2. xv. 3. Reasoning, xv. 3. Recollection, ii. 2. 10. ix. 1. 2. xv. 2. 3. Relaxation and bracing, xxxii. 3. 2. Repetition, why agreeable, xii. 3. 3. xxii. 2. Respiration affected by attention, xxxvi. 2. 1. Restlessness in fevers, xxxiv. 1. 2. Retrograde motions, xii. 5. 5. xxv. 6. xxix. 11. ---- of the stomach, xxv. 6. ---- of the skin, xxv. 9. ---- of fluids, how distinguished, xxix. 8. ---- how caused, xxix. 11. 5. ---- vegetable motions, xxix. 9. Retina is fibrous, iii. 2. xl. 1. ---- is active in vision, iii. 3. xl. 1. ---- excited into spasmodic motions, xl. 7. ---- is sensible during sleep, xviii. 5. xix. 8. Reverie, xix. 1. xxxiv. 3. ---- case of a sleep-walker, xix. 2. ---- is an epileptic disease, xix. 9. Rhymes in poetry, why agreeable, xxii. 2. Rheumatism, three kinds of, xxvi. 3. Rocking young children, xxi. 3. Ruminating animals, xxv. 1. S. Saliva produced by mercury, xxiv. 1. ---- by food, xxiv. 1. 1. ---- by ideas, xxiv. 1. 2. and 5. ---- by disordered volition, xxiv. 1. 7. Schirrous tumours revive, xii. 2. 2. Screaming in pain, xxxiv. 1. 3. Scrophula, its temperament, xxxi. 1. ---- xxviii. 2. xxxix. 4. 5. Scurvy of the lungs, xxvii. 2. Sea-sickness, xx. 4. ---- stopped by attention, xx. 5. Secretion, xxxiii. 1. xxxvii. ---- increased during sleep, xviii. 16. Seeds require oxygenation, xxxviii. 2. Sensation defined, ii. 2. 9. v. 2. xxxix. 8. 4. ---- diseases of, xxxiii. ---- from fibrous contractions, iv. 5. xii. 1. 6. ---- in an amputated limb, iii. 6. 3. ---- affects the whole sensorium, xi. 2. ---- produces volition, iv. 6. Sensibility increases during sleep, xviii. 15. Sensitive motions, viii. xxxiii. 2. xxxiv. 1. ---- fevers of two kinds, xxxiii. 1. 2. ---- ideas, xv. 2. 2. Sensorium defined, ii. 2. 1. Senses correct one another, xviii. 7. ---- distinguished from appetites, xxxiv. 1. 1. Sensorial power. See Spirit of Animation. ---- great expence of in the vital motions, xxxii. 3. 2. ---- two kinds of excited in sensitive fevers, xxxiii. 1. 3. ---- powers defined, v. 1. ---- motions distinguished from fibrous motions, v. 3. ---- not much, accumulated in sleep, xviii. 2. ---- powers, accumulation of, xii. 5. 1. ---- exhaustion of, xii. 4. 1. ---- wasted below natural in hot fits, xxxii. 9. 3. ---- less exertion of produces pain, xii. 5. 3. ---- less quantity of it, xii. 5. 4. Sensual motions distinguished from muscular, ii. 2. 7. Sex owing to the imagination of the father, xxxix. 7. 6. xxxix. 6. 3. xxxix. 6. 7. xxxix. 5. Shingles from inflamed kidney, xxxv. 2. 2. Shoulders broad, xxxi. 1. xxxix. 7. 6. Shuddering from cold, xxxiv. 1. 1. and 2. Sight, its accuracy in men, xvi. 6. Skin, skurf on it, xxvi. 1. Sleep suspends volition, xviii. 1. ---- defined, xviii. 21. ---- remote causes, xviii. 20. ---- sensation continues in it, xviii. 2. ---- from food, xxi. 1. ---- from rocking, uniform sounds, xxi. 1. ---- from wine and opium, xxi. 3. ---- why it invigorates, xii. 5. 1. ---- pulse slower and fuller, xxxii. 2. 2. ---- interrupted, xxvii. 2. ---- from breathing less oxygene, xviii. 20. ---- from being whirled on a millstone, xviii. 20. ---- from application of cold, xviii. 20. ---- induced by regular hours, xxxvi. 2. 2. Sleeping animals, xii. 2. 2. Sleep-walkers. See Reverie, xix. 1. Small-pox, xxxiii. 2. 6. xxxix. 6. 1. ---- eruption first on the face, why, xxxv. 1. 1. xxxiii. 2. 10. ---- the blood will not infect, xxxiii. 2. 10. ---- obeys lunations, xxxvi. 4. Smell, xiv. 5. xvi. 5. Smiling, origin of, xvi. 8. 4. Solidity, xiv. 2. 1. Somnambulation. See Reverie, xix. 1. Space, xiv. 2. 2. Spasm, doctrine of, xxxii. 10. Spectra, ocular, xl. ---- mistaken for spectres, xl. 2. ---- vary from long inspection, iii. 3. 5. Spirit of animation. See Sensorial Power. ---- of animation causes fibrous contraction, iv. 2. ii. 2. 1. xiv. 2. 4. ---- possesses solidity, figure, and other properties of matter, xiv. 2. 4. Spirits and angels, xiv. 2. 4. Stammering explained, xvii. 1. 10. xvii. 2. 10. Stimulus defined, ii. 2. 13. iv. 4. xii. 2. 1. ---- of various kinds, xi. 1. ---- with lessened effect, xii. 3. 1. ---- with greater effect, xii. 3. 3. ---- ceases to produce sensation, xii. 3. 6. Stomach and intestines, xxv. ---- inverted by great stimulus, xxv. 6. ---- its actions decreased in vomiting, xxxv. 1. 3. ---- a blow on it occasions death, xxv. 17. Stools black, xxvii. 2. Strangury, xxxv. 2. 1. Sucking before nativity, xvi. 4. Suckling children, sense of, xiv. 8. Suggestion defined, ii. 2. 10. xv. 2. 4. Sun and moon, their influence, xxxii. 6. Surprise, xvii. 3. 7. xviii. 17. Suspicion attends madness, xxxiv. 2. 4. Swallowing, act of, xxv. 1. xvi. 4. Sweat, cold, xxv. 9. xxix. 6. ---- in hot fit of fever, xxxii. 9. ---- in a morning, why, xviii. 15. Sweaty hands cured by lime, xxix. 4. 9. Swinging and rocking, why agreeable, xxi. 3. Sympathy, xxxv. 1. Syncope, xii. 7. 1. xxxiv. 1. 6. T. Tædium vitæ. See Ennui. Tape-worm, xxxix. 2. 3. Taste, sense of, xiv. 5. Tears, secretion of, xxiv. ---- from grief, xvi. 8. 2. ---- from tender pleasure, xvi. 8. 3. ---- from stimulus of nasal duct, xvi. 8. xxiv. 2. 4. ---- by volition, xxiv. 2. 6. Teeth decaying cause headachs, xxxv. 2. 1. Temperaments, xxxi. Theory of medicine, wanted. Preface. Thirst, sense of, xiv. 8. ---- why in dropsies, xxix. 5. Tickle themselves, children cannot, xvii. 3. 5. Tickling, xiv. 9. Time, xiv. 2. 2. xviii. 12. ---- lapse of, xv. 3. 6. ---- poetic and musical, why agreeable, xxii. 2. ---- dramatic, xviii. 12. Tooth-edge, xvi. 10. iii. 4. 3. xxii. 3. 3. Touch, sense of, xiv. 2. 1. ---- liable to vertigo, xxi. 9. ---- of various animals, xvi. 6. Trains of motions inverted, xii. 5. 5. Transfusion of blood in nervous fever, xxxii. 4. Translations of matter, xxix. 7. Typhus, best quantity of stimulus in, xii. 7. 8. ---- periods of observe lunar days, xxxii. 6. U. Ulcers, art of healing, xxxiii. 3. 2. ---- of the lungs, why difficult to heal, xxviii. 2. Uniformity in the fine arts, why agreeable, xxii. 2. Urine pale in intoxication, xxi. 6. ---- paucity of in anasarca, why, xxix. 5. ---- its passage from intestines to bladder, xxix. 3. ---- copious during sleep, xviii. 15. V. Variation, perpetual, of irritability, xii. 2. 1. Vegetable buds are inferior animals, xiii. 1. ---- exactly resemble their parents, xxxix. ---- possess sensation and volition, xiii. 2. ---- have associate and retrograde motions, xiii. 4. xxix. 9. ---- their anthers and stigmas are alive, xiii. 5. ---- have organs of sense and ideas, xiii. 5. ---- contend for light and air, xxxix. 4. 8. ---- duplicature of their flowers, xxxix. 4. 4. Veins are absorbents, xxvii. 1. ---- paralysis of, xxvii. 1. Venereal orgasm of brutes, xxxii. 6. Venesection in nervous pains, xxxii. 5. 4. Verbs of three kinds, xv. 3. 4. Verses, their measure, xxii. 2. Vertigo, xx. ---- defined, xx. 11. ---- in looking from a tower, xx. 1. ---- in a ship at sea, xx. 4. ---- of all the senses, xxi. 9. ---- by intoxication, xxxv. 1. 2. Vibratory motions perceived after sailing, xx. 5. xx. 10. Vinegar makes the lips pale, xxvii. 1. Vis medicatrix of nature, xxxix. 4. 7. Vision, sense of, xiv. 3. Volition defined, v. 2. xxxiv. 1. ---- affects the whole sensorium, xi. 2. ---- diseases of, xxxiv. Voluntarity, xi. 2. 4. Voluntary motions, ix. xxxiv. 1. Voluntary ideas, xv. 2. 3. ---- criterion of, xi. 2. 3. xxxiv. 1. Vomiting from vertigo, xx. 8. ---- from drunkenness, xx. 8. xxi. 6. ---- by intervals, xxv. 8. ---- by voluntary efforts, xxv. 6. ---- of two kinds, xxxv. 1. 3. ---- in cold fit of fever, xxxii. 9. 1. ---- stopped by quicksilver, xxv. 16. ---- weakens the pulse, xxv. 17. W. Waking, how, xviii. 14. Walking, how learnt, xvi. 3. Warmth in sleep, why, xviii. 15. Weakness defined, xii. 1. 3. xii. 2. 1. xxxii. 3. 2. ---- cure of, xii. 7. 8. ---- See Debility. Wit producing laughter, xxxiv. 1. 4. World generated, xxxix. 4. 8. * * * * * END OF THE FIRST VOLUME. 
2922	----	THE PAST CONDITION OF ORGANIC NATURE Lecture II. (of VI.), Lectures To Working Men, at the Museum of Practical Geology, 1863, On Darwin's work: "Origin of Species". by Thomas H. Huxley IN the lecture which I delivered last Monday evening, I endeavoured to sketch in a very brief manner, but as well as the time at my disposal would permit, the present condition of organic nature, meaning by that large title simply an indication of the great, broad, and general principles which are to be discovered by those who look attentively at the phenomena of organic nature as at present displayed. The general result of our investigations might be summed up thus: we found that the multiplicity of the forms of animal life, great as that may be, may be reduced to a comparatively few primitive plans or types of construction; that a further study of the development of those different forms revealed to us that they were again reducible, until we at last brought the infinite diversity of animal, and even vegetable life, down to the primordial form of a single cell. We found that our analysis of the organic world, whether animals or plants, showed, in the long run, that they might both be reduced into, and were, in fact, composed of, the same constituents. And we saw that the plant obtained the materials constituting its substance by a peculiar combination of matters belonging entirely to the inorganic world; that, then, the animal was constantly appropriating the nitrogenous matters of the plant to its own nourishment, and returning them back to the inorganic world, in what we spoke of as its waste; and that finally, when the animal ceased to exist, the constituents of its body were dissolved and transmitted to that inorganic world whence they had been at first abstracted. Thus we saw in both the blade of grass and the horse but the same elements differently combined and arranged. We discovered a continual circulation going on,--the plant drawing in the elements of inorganic nature and combining them into food for the animal creation; the animal borrowing from the plant the matter for its own support, giving off during its life products which returned immediately to the inorganic world; and that, eventually, the constituent materials of the whole structure of both animals and plants were thus returned to their original source: there was a constant passage from one state of existence to another, and a returning back again. Lastly, when we endeavoured to form some notion of the nature of the forces exercised by living beings, we discovered that they--if not capable of being subjected to the same minute analysis as the constituents of those beings themselves--that they were correlative with--that they were the equivalents of the forces of inorganic nature--that they were, in the sense in which the term is now used, convertible with them. That was our general result. And now, leaving the Present, I must endeavour in the same manner to put before you the facts that are to be discovered in the Past history of the living world, in the past conditions of organic nature. We have, to-night, to deal with the facts of that history--a history involving periods of time before which our mere human records sink into utter insignificance--a history the variety and physical magnitude of whose events cannot even be foreshadowed by the history of human life and human phenomena--a history of the most varied and complex character. We must deal with the history, then, in the first place, as we should deal with all other histories. The historical student knows that his first business should be to inquire into the validity of his evidence, and the nature of the record in which the evidence is contained, that he may be able to form a proper estimate of the correctness of the conclusions which have been drawn from that evidence. So, here, we must pass, in the first place, to the consideration of a matter which may seem foreign to the question under discussion. We must dwell upon the nature of the records, and the credibility of the evidence they contain; we must look to the completeness or incompleteness of those records themselves, before we turn to that which they contain and reveal. The question of the credibility of the history, happily for us, will not require much consideration, for, in this history, unlike those of human origin, there can be no cavilling, no differences as to the reality and truth of the facts of which it is made up; the facts state themselves, and are laid out clearly before us. But, although one of the greatest difficulties of the historical student is cleared out of our path, there are other difficulties--difficulties in rightly interpreting the facts as they are presented to us--which may be compared with the greatest difficulties of any other kinds of historical study. What is this record of the past history of the globe, and what are the questions which are involved in an inquiry into its completeness or incompleteness? That record is composed of mud; and the question which we have to investigate this evening resolves itself into a question of the formation of mud. You may think, perhaps, that this is a vast step--of almost from the sublime to the ridiculous--from the contemplation of the history of the past ages of the world's existence to the consideration of the history of the formation of mud! But, in nature, there is nothing mean and unworthy of attention; there is nothing ridiculous or contemptible in any of her works; and this inquiry, you will soon see, I hope, takes us to the very root and foundations of our subject. How, then, is mud formed? Always, with some trifling exception, which I need not consider now--always, as the result of the action of water, wearing down and disintegrating the surface of the earth and rocks with which it comes in contact--pounding and grinding it down, and carrying the particles away to places where they cease to be disturbed by this mechanical action, and where they can subside and rest. For the ocean, urged by winds, washes, as we know, a long extent of coast, and every wave, loaded as it is with particles of sand and gravel as it breaks upon the shore, does something towards the disintegrating process. And thus, slowly but surely, the hardest rocks are gradually ground down to a powdery substance; and the mud thus formed, coarser or finer, as the case may be, is carried by the rush of the tides, or currents, till it reaches the comparatively deeper parts of the ocean, in which it can sink to the bottom, that is, to parts where there is a depth of about fourteen or fifteen fathoms, a depth at which the water is, usually, nearly motionless, and in which, of course, the finer particles of this detritus, or mud as we call it, sinks to the bottom. Or, again, if you take a river, rushing down from its mountain sources, brawling over the stones and rocks that intersect its path, loosening, removing, and carrying with it in its downward course the pebbles and lighter matters from its banks, it crushes and pounds down the rocks and earths in precisely the same way as the wearing action of the sea waves. The matters forming the deposit are torn from the mountain-side and whirled impetuously into the valley, more slowly over the plain, thence into the estuary, and from the estuary they are swept into the sea. The coarser and heavier fragments are obviously deposited first, that is, as soon as the current begins to lose its force by becoming amalgamated with the stiller depths of the ocean, but the finer and lighter particles are carried further on, and eventually deposited in a deeper and stiller portion of the ocean. It clearly follows from this that mud gives us a chronology; for it is evident that supposing this, which I now sketch, to be the sea bottom, and supposing this to be a coast-line; from the washing action of the sea upon the rock, wearing and grinding it down into a sediment of mud, the mud will be carried down, and at length, deposited in the deeper parts of this sea bottom, where it will form a layer; and then, while that first layer is hardening, other mud which is coming from the same source will, of course, be carried to the same place; and, as it is quite impossible for it to get beneath the layer already there, it deposits itself above it, and forms another layer, and in that way you gradually have layers of mud constantly forming and hardening one above the other, and conveying a record of time. It is a necessary result of the operation of the law of gravitation that the uppermost layer shall be the youngest and the lowest the oldest, and that the different beds shall be older at any particular point or spot in exactly the ratio of their depth from the surface. So that if they were upheaved afterwards, and you had a series of these different layers of mud, converted into sandstone, or limestone, as the case might be, you might be sure that the bottom layer was deposited first, and that the upper layers were formed afterwards. Here, you see, is the first step in the history--these layers of mud give us an idea of time. The whole surface of the earth,--I speak broadly, and leave out minor qualifications,--is made up of such layers of mud, so hard, the majority of them, that we call them rock whether limestone or sandstone, or other varieties of rock. And, seeing that every part of the crust of the earth is made up in this way, you might think that the determination of the chronology, the fixing of the time which it has taken to form this crust is a comparatively simple matter. Take a broad average, ascertain how fast the mud is deposited upon the bottom of the sea, or in the estuary of rivers; take it to be an inch, or two, or three inches a year, or whatever you may roughly estimate it at; then take the total thickness of the whole series of stratified rocks, which geologists estimate at twelve or thirteen miles, or about seventy thousand feet, make a sum in short division, divide the total thickness by that of the quantity deposited in one year, and the result will, of course, give you the number of years which the crust has taken to form. Truly, that looks a very simple process! It would be so except for certain difficulties, the very first of which is that of finding how rapidly sediments are deposited; but the main difficulty--a difficulty which renders any certain calculations of such a matter out of the question--is this, the sea-bottom on which the deposit takes place is continually shifting. Instead of the surface of the earth being that stable, fixed thing that it is popularly believed to be, being, in common parlance, the very emblem of fixity itself, it is incessantly moving, and is, in fact, as unstable as the surface of the sea, except that its undulations are infinitely slower and enormously higher and deeper. Now, what is the effect of this oscillation? Take the case to which I have previously referred. The finer or coarser sediments that are carried down by the current of the river, will only be carried out a certain distance, and eventually, as we have already seen, on reaching the stiller part of the ocean, will be deposited at the bottom. Let C y (Fig. 4) be the sea-bottom, y D the shore, x y the sea-level, then the coarser deposit will subside over the region B, the finer over A, while beyond A there will be no deposit at all; and, consequently, no record will be kept, simply because no deposit is going on. Now, suppose that the whole land, C, D, which we have regarded as stationary, goes down, as it does so, both A and B go further out from the shore, which will be at y1; x1, y1, being the new sea-level. The consequence will be that the layer of mud (A), being now, for the most part, further than the force of the current is strong enough to convey even the finest 'debris', will, of course, receive no more deposits, and having attained a certain thickness will now grow no thicker. We should be misled in taking the thickness of that layer, whenever it may be exposed to our view, as a record of time in the manner in which we are now regarding this subject, as it would give us only an imperfect and partial record: it would seem to represent too short a period of time. [Illustration: Fig.4.] Suppose, on the other hand, that the land (C D) had gone on rising slowly and gradually--say an inch or two inches in the course of a century,--what would be the practical effect of that movement? Why, that the sediment A and B which has been already deposited, would eventually be brought nearer to the shore-level, and again subjected to the wear and tear of the sea; and directly the sea begins to act upon it, it would of course soon cut up and carry it away, to a greater or less extent, to be re-deposited further out. Well, as there is, in all probability, not one single spot on the whole surface of the earth, which has not been up and down in this way a great many times, it follows that the thickness of the deposits formed at any particular spot cannot be taken (even supposing we had at first obtained correct data as to the rate at which they took place) as affording reliable information as to the period of time occupied in its deposit. So that you see it is absolutely necessary from these facts, seeing that our record entirely consists of accumulations of mud, superimposed one on the other; seeing in the next place that any particular spots on which accumulations have occurred, have been constantly moving up and down, and sometimes out of the reach of a deposit, and at other times its own deposit broken up and carried away, it follows that our record must be in the highest degree imperfect, and we have hardly a trace left of thick deposits, or any definite knowledge of the area that they occupied, in a great many cases. And mark this! That supposing even that the whole surface of the earth had been accessible to the geologist,--that man had had access to every part of the earth, and had made sections of the whole, and put them all together,--even then his record must of necessity be imperfect. But to how much has man really access? If you will look at this Map you will see that it represents the proportion of the sea to the earth: this coloured part indicates all the dry land, and this other portion is the water. You will notice at once that the water covers three-fifths of the whole surface of the globe, and has covered it in the same manner ever since man has kept any record of his own observations, to say nothing of the minute period during which he has cultivated geological inquiry. So that three-fifths of the surface of the earth is shut out from us because it is under the sea. Let us look at the other two-fifths, and see what are the countries in which anything that may be termed searching geological inquiry has been carried out: a good deal of France, Germany, and Great Britain and Ireland, bits of Spain, of Italy, and of Russia, have been examined, but of the whole great mass of Africa, except parts of the southern extremity, we know next to nothing; little bits of India, but of the greater part of the Asiatic continent nothing; bits of the Northern American States and of Canada, but of the greater part of the continent of North America, and in still larger proportion, of South America, nothing! Under these circumstances, it follows that even with reference to that kind of imperfect information which we can possess, it is only of about the ten-thousandth part of the accessible parts of the earth that has been examined properly. Therefore, it is with justice that the most thoughtful of those who are concerned in these inquiries insist continually upon the imperfection of the geological record; for, I repeat, it is absolutely necessary, from the nature of things, that that record should be of the most fragmentary and imperfect character. Unfortunately this circumstance has been constantly forgotten. Men of science, like young colts in a fresh pasture, are apt to be exhilarated on being turned into a new field of inquiry, to go off at a hand-gallop, in total disregard of hedges and ditches, losing sight of the real limitation of their inquiries, and to forget the extreme imperfection of what is really known. Geologists have imagined that they could tell us what was going on at all parts of the earth's surface during a given epoch; they have talked of this deposit being contemporaneous with that deposit, until, from our little local histories of the changes at limited spots of the earth's surface, they have constructed a universal history of the globe as full of wonders and portents as any other story of antiquity. But what does this attempt to construct a universal history of the globe imply? It implies that we shall not only have a precise knowledge of the events which have occurred at any particular point, but that we shall be able to say what events, at any one spot, took place at the same time with those at other spots. Let us see how far that is in the nature of things practicable. Suppose that here I make a section of the Lake of Killarney, and here the section of another lake--that of Loch Lomond in Scotland for instance. The rivers that flow into them are constantly carrying down deposits of mud, and beds, or strata, are being as constantly formed, one above the other, at the bottom of those lakes. Now, there is not a shadow of doubt that in these two lakes the lower beds are all older than the upper--there is no doubt about that; but what does 'this' tell us about the age of any given bed in Loch Lomond, as compared with that of any given bed in the Lake of Killarney? It is, indeed, obvious that if any two sets of deposits are separated and discontinuous, there is absolutely no means whatever given you by the nature of the deposit of saying whether one is much younger or older than the other; but you may say, as many have said and think, that the case is very much altered if the beds which we are comparing are continuous. Suppose two beds of mud hardened into rock,--A and B-are seen in section. (Fig. 5.) [Illustration: Fig. 5.] Well, you say, it is admitted that the lowermost bed is always the older. Very well; B, therefore, is older than A. No doubt, 'as a whole', it is so; or if any parts of the two beds which are in the same vertical line are compared, it is so. But suppose you take what seems a very natural step further, and say that the part 'a' of the bed A is younger than the part 'b' of the bed B. Is this sound reasoning? If you find any record of changes taking place at 'b', did they occur before any events which took place while 'a' was being deposited? It looks all very plain sailing, indeed, to say that they did; and yet there is no proof of anything of the kind. As the former Director of this Institution, Sir H. De la Beche, long ago showed, this reasoning may involve an entire fallacy. It is extremely possible that 'a' may have been deposited ages before 'b'. It is very easy to understand how that can be. To return to Fig. 4; when A and B were deposited, they were 'substantially' contemporaneous; A being simply the finer deposit, and B the coarser of the same detritus or waste of land. Now suppose that that sea-bottom goes down (as shown in Fig. 4), so that the first deposit is carried no farther than 'a', forming the bed Al, and the coarse no farther than 'b', forming the bed B1, the result will be the formation of two continuous beds, one of fine sediment (A A1) over-lapping another of coarse sediment (B B1). Now suppose the whole sea-bottom is raised up, and a section exposed about the point Al; no doubt, 'at this spot', the upper bed is younger than the lower. But we should obviously greatly err if we concluded that the mass of the upper bed at A was younger than the lower bed at B; for we have just seen that they are contemporaneous deposits. Still more should we be in error if we supposed the upper bed at A to be younger than the continuation of the lower bed at Bl; for A was deposited long before B1. In fine, if, instead of comparing immediately adjacent parts of two beds, one of which lies upon another, we compare distant parts, it is quite possible that the upper may be any number of years older than the under, and the under any number of years younger than the upper. Now you must not suppose that I put this before you for the purpose of raising a paradoxical difficulty; the fact is, that the great mass of deposits have taken place in sea-bottoms which are gradually sinking, and have been formed under the very conditions I am here supposing. Do not run away with the notion that this subverts the principle I laid down at first. The error lies in extending a principle which is perfectly applicable to deposits in the same vertical line to deposits which are not in that relation to one another. It is in consequence of circumstances of this kind, and of others that I might mention to you, that our conclusions on and interpretations of the record are really and strictly only valid so long as we confine ourselves to one vertical section. I do not mean to tell you that there are no qualifying circumstances, so that, even in very considerable areas, we may safely speak of conformably superimposed beds being older or younger than others at many different points. But we can never be quite sure in coming to that conclusion, and especially we cannot be sure if there is any break in their continuity, or any very great distance between the points to be compared. Well now, so much for the record itself,--so much for its imperfections,--so much for the conditions to be observed in interpreting it, and its chronological indications, the moment we pass beyond the limits of a vertical linear section. Now let us pass from the record to that which it contains,--from the book itself to the writing and the figures on its pages. This writing and these figures consist of remains of animals and plants which, in the great majority of cases, have lived and died in the very spot in which we now find them, or at least in the immediate vicinity. You must all of you be aware--and I referred to the fact in my last lecture--that there are vast numbers of creatures living at the bottom of the sea. These creatures, like all others, sooner or later die, and their shells and hard parts lie at the bottom; and then the fine mud which is being constantly brought down by rivers and the action of the wear and tear of the sea, covers them over and protects them from any further change or alteration; and, of course, as in process of time the mud becomes hardened and solidified, the shells of these animals are preserved and firmly imbedded in the limestone or sandstone which is being thus formed. You may see in the galleries of the Museum up stairs specimens of limestones in which such fossil remains of existing animals are imbedded. There are some specimens in which turtles' eggs have been imbedded in calcareous sand, and before the sun had hatched the young turtles, they became covered over with calcareous mud, and thus have been preserved and fossilized. Not only does this process of imbedding and fossilization occur with marine and other aquatic animals and plants, but it affects those land animals and plants which are drifted away to sea, or become buried in bogs or morasses; and the animals which have been trodden down by their fellows and crushed in the mud at the river's bank, as the herd have come to drink. In any of these cases, the organisms may be crushed or be mutilated, before or after putrefaction, in such a manner that perhaps only a part will be left in the form in which it reaches us. It is, indeed, a most remarkable fact, that it is quite an exceptional case to find a skeleton of any one of all the thousands of wild land animals that we know are constantly being killed, or dying in the course of nature: they are preyed on and devoured by other animals or die in places where their bodies are not afterwards protected by mud. There are other animals existing in the sea, the shells of which form exceedingly large deposits. You are probably aware that before the attempt was made to lay the Atlantic telegraphic cable, the Government employed vessels in making a series of very careful observations and soundings of the bottom of the Atlantic; and although, as we must all regret, up to the present time that project has not succeeded, we have the satisfaction of knowing that it yielded some most remarkable results to science. The Atlantic Ocean had to be sounded right across, to depths of several miles in some places, and the nature of its bottom was carefully ascertained. Well, now, a space of about 1,000 miles wide from east to west, and I do not exactly know how many from north to south, but at any rate 600 or 700 miles, was carefully examined, and it was found that over the whole of that immense area an excessively fine chalky mud is being deposited; and this deposit is entirely made up of animals whose hard parts are deposited in this part of the ocean, and are doubtless gradually acquiring solidity and becoming metamorphosed into a chalky limestone. Thus, you see, it is quite possible in this way to preserve unmistakable records of animal and vegetable life. Whenever the sea-bottom, by some of those undulations of the earth's crust that I have referred to, becomes upheaved, and sections or borings are made, or pits are dug, then we become able to examine the contents and constituents of these ancient sea-bottoms, and find out what manner of animals lived at that period. Now it is a very important consideration in its bearing on the completeness of the record, to inquire how far the remains contained in these fossiliferous limestones are able to convey anything like an accurate or complete account of the animals which were in existence at the time of its formation. Upon that point we can form a very clear judgment, and one in which there is no possible room for any mistake. There are of course a great number of animals--such as jelly-fishes, and other animals--without any hard parts, of which we cannot reasonably expect to find any traces whatever: there is nothing of them to preserve. Within a very short time, you will have noticed, after they are removed from the water, they dry up to a mere nothing; certainly they are not of a nature to leave any very visible traces of their existence on such bodies as chalk or mud. Then again, look at land animals; it is, as I have said, a very uncommon thing to find a land animal entire after death. Insects and other carnivorous animals very speedily pull them to pieces, putrefaction takes place, and so, out of the hundreds of thousands that are known to die every year, it is the rarest thing in the world to see one imbedded in such a way that its remains would be preserved for a lengthened period. Not only is this the case, but even when animal remains have been safely imbedded, certain natural agents may wholly destroy and remove them. Almost all the hard parts of animals--the bones and so on--are composed chiefly of phosphate of lime and carbonate of lime. Some years ago, I had to make an inquiry into the nature of some very curious fossils sent to me from the North of Scotland. Fossils are usually hard bony structures that have become imbedded in the way I have described, and have gradually acquired the nature and solidity of the body with which they are associated; but in this case I had a series of 'holes' in some pieces of rock, and nothing else. Those holes, however, had a certain definite shape about them, and when I got a skilful workman to make castings of the interior of these holes, I found that they were the impressions of the joints of a backbone and of the armour of a great reptile, twelve or more feet long. This great beast had died and got buried in the sand; the sand had gradually hardened over the bones, but remained porous. Water had trickled through it, and that water being probably charged with a superfluity of carbonic acid, had dissolved all the phosphate and carbonate of lime, and the bones themselves had thus decayed and entirely disappeared; but as the sandstone happened to have consolidated by that time, the precise shape of the bones was retained. If that sandstone had remained soft a little longer, we should have known nothing whatsoever of the existence of the reptile whose bones it had encased. How certain it is that a vast number of animals which have existed at one period on this earth have entirely perished, and left no trace whatever of their forms, may be proved to you by other considerations. There are large tracts of sandstone in various parts of the world, in which nobody has yet found anything but footsteps. Not a bone of any description, but an enormous number of traces of footsteps. There is no question about them. There is a whole valley in Connecticut covered with these footsteps, and not a single fragment of the animals which made them has yet been found. Let me mention another case while upon that matter, which is even more surprising than those to which I have yet referred. There is a limestone formation near Oxford, at a place called Stonesfield, which has yielded the remains of certain very interesting mammalian animals, and up to this time, if I recollect rightly, there have been found seven specimens of its lower jaws, and not a bit of anything else, neither limb-bones nor skull, or any part whatever; not a fragment of the whole system! Of course, it would be preposterous to imagine that the beasts had nothing else but a lower jaw! The probability is, as Dr. Buckland showed, as the result of his observations on dead dogs in the river Thames, that the lower jaw, not being secured by very firm ligaments to the bones of the head, and being a weighty affair, would easily be knocked off, or might drop away from the body as it floated in water in a state of decomposition. The jaw would thus be deposited immediately, while the rest of the body would float and drift away altogether, ultimately reaching the sea, and perhaps becoming destroyed. The jaw becomes covered up and preserved in the river silt, and thus it comes that we have such a curious circumstance as that of the lower jaws in the Stonesfield slates. So that, you see, faulty as these layers of stone in the earth's crust are, defective as they necessarily are as a record, the account of contemporaneous vital phenomena presented by them is, by the necessity of the case, infinitely more defective and fragmentary. It was necessary that I should put all this very strongly before you, because, otherwise, you might have been led to think differently of the completeness of our knowledge by the next facts I shall state to you. The researches of the last three-quarters of a century have, in truth, revealed a wonderful richness of organic life in those rocks. Certainly not fewer than thirty or forty thousand different species of fossils have been discovered. You have no more ground for doubting that these creatures really lived and died at or near the places in which we find them than you have for like scepticism about a shell on the sea-shore. The evidence is as good in the one case as in the other. Our next business is to look at the general character of these fossil remains, and it is a subject which it will be requisite to consider carefully; and the first point for us is to examine how much the extinct 'Flora' and 'Fauna' as a 'whole'--disregarding altogether the 'succession' of their constituents, of which I shall speak afterwards--differ from the 'Flora' and 'Fauna' of the present day;--how far they differ in what we 'do' know about them, leaving altogether out of consideration speculations based upon what we 'do not' know. I strongly imagine that if it were not for the peculiar appearance that fossilised animals have, any of you might readily walk through a museum which contains fossil remains mixed up with those of the present forms of life, and I doubt very much whether your uninstructed eyes would lead you to see any vast or wonderful difference between the two. If you looked closely, you would notice, in the first place, a great many things very like animals with which you are acquainted now: you would see differences of shape and proportion, but on the whole a close similarity. I explained what I meant by ORDERS the other day, when I described the animal kingdom as being divided in sub-kingdoms, classes and orders. If you divide the animal kingdom into orders, you will find that there are about one hundred and twenty. The number may vary on one side or the other, but this is a fair estimate. That is the sum total of the orders of all the animals which we know now, and which have been known in past times, and left remains behind. Now, how many of those are absolutely extinct? That is to say, how many of these orders of animals have lived at a former period of the world's history, but have at present no representatives? That is the sense in which I meant to use the word "extinct." I mean that those animals did live on this earth at one time, but have left no one of their kind with us at the present moment. So that estimating the number of extinct animals is a sort of way of comparing the past creation as a whole with the present as a whole. Among the mammalia and birds there are none extinct; but when we come to the reptiles there is a most wonderful thing: out of the eight orders, or thereabouts, which you can make among reptiles, one-half are extinct. These diagrams of the plesiosaurus, the ichthyosaurus, the pterodactyle, give you a notion of some of these extinct reptiles. And here is a cast of the pterodactyle and bones of the ichthyosaurus and the plesiosaurus, just as fresh as if it had been recently dug up in a churchyard. Thus, in the reptile class, there are no less than half of the orders which are absolutely extinct. If we turn to the 'Amphibia', there was one extinct order, the Labyrinthodonts, typified by the large salamander-like beast shown in this diagram. No order of fishes is known to be extinct. Every fish that we find in the strata--to which I have been referring--can be identified and placed in one of the orders which exist at the present day. There is not known to be a single ordinal form of insect extinct. There are only two orders extinct among the 'Crustacea'. There is not known to be an extinct order of these creatures, the parasitic and other worms; but there are two, not to say three, absolutely extinct orders of this class, the 'Echinodermata'; out of all the orders of the 'Coelenterata' and 'Protozoa' only one, the Rugose Corals. So that, you see, out of somewhere about 120 orders of animals, taking them altogether, you will not, at the outside estimate, find above ten or a dozen extinct. Summing up all the orders of animals which have left remains behind them, you will not find above ten or a dozen which cannot be arranged with those of the present day; that is to say, that the difference does not amount to much more than ten per cent.: and the proportion of extinct orders of plants is still smaller. I think that that is a very astounding, a most astonishing fact, seeing the enormous epochs of time which have elapsed during the constitution of the surface of the earth as it at present exists; it is, indeed, a most astounding thing that the proportion of extinct ordinal types should be so exceedingly small. But now, there is another point of view in which we must look at this past creation. Suppose that we were to sink a vertical pit through the floor beneath us, and that I could succeed in making a section right through in the direction of New Zealand, I should find in each of the different beds through which I passed the remains of animals which I should find in that stratum and not in the others. First, I should come upon beds of gravel or drift containing the bones of large animals, such as the elephant, rhinoceros, and cave tiger. Rather curious things to fall across in Piccadilly! If I should dig lower still, I should come upon a bed of what we call the London clay, and in this, as you will see in our galleries upstairs, are found remains of strange cattle, remains of turtles, palms, and large tropical fruits; with shell-fish such as you see the like of now only in tropical regions. If I went below that, I should come upon the chalk, and there I should find something altogether different, the remains of ichthyosauri and pterodactyles, and ammonites, and so forth. I do not know what Mr. Godwin Austin would say comes next, but probably rocks containing more ammonites, and more ichthyosauri and plesiosauri, with a vast number of other things; and under that I should meet with yet older rocks, containing numbers of strange shells and fishes; and in thus passing from the surface to the lowest depths of the earth's crust, the forms of animal life and vegetable life which I should meet with in the successive beds would, looking at them broadly, be the more different the further that I went down. Or, in other words, inasmuch as we started with the clear principle, that in a series of naturally-disposed mud beds the lowest are the oldest, we should come to this result, that the further we go back in time the more difference exists between the animal and vegetable life of an epoch and that which now exists. That was the conclusion to which I wished to bring you at the end of this Lecture. 
2923	----	THE METHOD BY WHICH THE CAUSES OF THE PRESENT AND PAST CONDITIONS OF ORGANIC NATURE ARE TO BE DISCOVERED.--THE ORIGINATION OF LIVING BEINGS Lecture III. (of VI.), Lectures To Working Men, at the Museum of Practical Geology, 1863, On Darwin's work: "Origin of Species". By Thomas H. Huxley In the two preceding lectures I have endeavoured to indicate to you the extent of the subject-matter of the inquiry upon which we are engaged; and now, having thus acquired some conception of the Past and Present phenomena of Organic Nature, I must now turn to that which constitutes the great problem which we have set before ourselves;--I mean, the question of what knowledge we have of the causes of these phenomena of organic nature, and how such knowledge is obtainable. Here, on the threshold of the inquiry, an objection meets us. There are in the world a number of extremely worthy, well-meaning persons, whose judgments and opinions are entitled to the utmost respect on account of their sincerity, who are of opinion that Vital Phenomena, and especially all questions relating to the origin of vital phenomena, are questions quite apart from the ordinary run of inquiry, and are, by their very nature, placed out of our reach. They say that all these phenomena originated miraculously, or in some way totally different from the ordinary course of nature, and that therefore they conceive it to be futile, not to say presumptuous, to attempt to inquire into them. To such sincere and earnest persons, I would only say, that a question of this kind is not to be shelved upon theoretical or speculative grounds. You may remember the story of the Sophist who demonstrated to Diogenes in the most complete and satisfactory manner that he could not walk; that, in fact, all motion was an impossibility; and that Diogenes refuted him by simply getting up and walking round his tub. So, in the same way, the man of science replies to objections of this kind, by simply getting up and walking onward, and showing what science has done and is doing--by pointing to that immense mass of facts which have been ascertained and systematized under the forms of the great doctrines of Morphology, of Development, of Distribution, and the like. He sees an enormous mass of facts and laws relating to organic beings, which stand on the same good sound foundation as every other natural law; and therefore, with this mass of facts and laws before us, therefore, seeing that, as far as organic matters have hitherto been accessible and studied, they have shown themselves capable of yielding to scientific investigation, we may accept this as proof that order and law reign there as well as in the rest of nature; and the man of science says nothing to objectors of this sort, but supposes that we can and shall walk to a knowledge of the origin of organic nature, in the same way that we have walked to a knowledge of the laws and principles of the inorganic world. But there are objectors who say the same from ignorance and ill-will. To such I would reply that the objection comes ill from them, and that the real presumption, I may almost say the real blasphemy, in this matter, is in the attempt to limit that inquiry into the causes of phenomena which is the source of all human blessings, and from which has sprung all human prosperity and progress; for, after all, we can accomplish comparatively little; the limited range of our own faculties bounds us on every side,--the field of our powers of observation is small enough, and he who endeavours to narrow the sphere of our inquiries is only pursuing a course that is likely to produce the greatest harm to his fellow-men. But now, assuming, as we all do, I hope, that these phenomena are properly accessible to inquiry, and setting out upon our search into the causes of the phenomena of organic nature, or, at any rate, setting out to discover how much we at present know upon these abstruse matters, the question arises as to what is to be our course of proceeding, and what method we must lay down for our guidance. I reply to that question, that our method must be exactly the same as that which is pursued in any other scientific inquiry, the method of scientific investigation being the same for all orders of facts and phenomena whatsoever. I must dwell a little on this point, for I wish you to leave this room with a very clear conviction that scientific investigation is not, as many people seem to suppose, some kind of modern black art. I say that you might easily gather this impression from the manner in which many persons speak of scientific inquiry, or talk about inductive and deductive philosophy, or the principles of the "Baconian philosophy." I do protest that, of the vast number of cants in this world, there are none, to my mind, so contemptible as the pseudoscientific cant which is talked about the "Baconian philosophy." To hear people talk about the great Chancellor--and a very great man he certainly was,--you would think that it was he who had invented science, and that there was no such thing as sound reasoning before the time of Queen Elizabeth. Of course you say, that cannot possibly be true; you perceive, on a moment's reflection, that such an idea is absurdly wrong, and yet, so firmly rooted is this sort of impression,--I cannot call it an idea, or conception,--the thing is too absurd to be entertained,--but so completely does it exist at the bottom of most men's minds, that this has been a matter of observation with me for many years past. There are many men who, though knowing absolutely nothing of the subject with which they may be dealing, wish, nevertheless, to damage the author of some view with which they think fit to disagree. What they do, then, is not to go and learn something about the subject, which one would naturally think the best way of fairly dealing with it; but they abuse the originator of the view they question, in a general manner, and wind up by saying that, "After all, you know, the principles and method of this author are totally opposed to the canons of the Baconian philosophy." Then everybody applauds, as a matter of course, and agrees that it must be so. But if you were to stop them all in the middle of their applause, you would probably find that neither the speaker nor his applauders could tell you how or in what way it was so; neither the one nor the other having the slightest idea of what they mean when they speak of the "Baconian philosophy." You will understand, I hope, that I have not the slightest desire to join in the outcry against either the morals, the intellect, or the great genius of Lord Chancellor Bacon. He was undoubtedly a very great man, let people say what they will of him; but notwithstanding all that he did for philosophy, it would be entirely wrong to suppose that the methods of modern scientific inquiry originated with him, or with his age; they originated with the first man, whoever he was; and indeed existed long before him, for many of the essential processes of reasoning are exerted by the higher order of brutes as completely and effectively as by ourselves. We see in many of the brute creation the exercise of one, at least, of the same powers of reasoning as that which we ourselves employ. The method of scientific investigation is nothing but the expression of the necessary mode of working of the human mind. It is simply the mode at which all phenomena are reasoned about, rendered precise and exact. There is no more difference, but there is just the same kind of difference, between the mental operations of a man of science and those of an ordinary person, as there is between the operations and methods of a baker or of a butcher weighing out his goods in common scales, and the operations of a chemist in performing a difficult and complex analysis by means of his balance and finely-graduated weights. It is not that the action of the scales in the one case, and the balance in the other, differ in the principles of their construction or manner of working; but the beam of one is set on an infinitely finer axis than the other, and of course turns by the addition of a much smaller weight. You will understand this better, perhaps, if I give you some familiar example. You have all heard it repeated, I dare say, that men of science work by means of Induction and Deduction, and that by the help of these operations, they, in a sort of sense, wring from Nature certain other things, which are called Natural Laws, and Causes, and that out of these, by some cunning skill of their own, they build up Hypotheses and Theories. And it is imagined by many, that the operations of the common mind can be by no means compared with these processes, and that they have to be acquired by a sort of special apprenticeship to the craft. To hear all these large words, you would think that the mind of a man of science must be constituted differently from that of his fellow men; but if you will not be frightened by terms, you will discover that you are quite wrong, and that all these terrible apparatus are being used by yourselves every day and every hour of your lives. There is a well-known incident in one of Moliere's plays, where the author makes the hero express unbounded delight on being told that he had been talking prose during the whole of his life. In the same way, I trust, that you will take comfort, and be delighted with yourselves, on the discovery that you have been acting on the principles of inductive and deductive philosophy during the same period. Probably there is not one here who has not in the course of the day had occasion to set in motion a complex train of reasoning, of the very same kind, though differing of course in degree, as that which a scientific man goes through in tracing the causes of natural phenomena. A very trivial circumstance will serve to exemplify this. Suppose you go into a fruiterer's shop, wanting an apple,--you take up one, and, on biting it, you find it is sour; you look at it, and see that it is hard and green. You take up another one, and that too is hard, green, and sour. The shopman offers you a third; but, before biting it, you examine it, and find that it is hard and green, and you immediately say that you will not have it, as it must be sour, like those that you have already tried. Nothing can be more simple than that, you think; but if you will take the trouble to analyze and trace out into its logical elements what has been done by the mind, you will be greatly surprised. In the first place, you have performed the operation of Induction. You found that, in two experiences, hardness and greenness in apples go together with sourness. It was so in the first case, and it was confirmed by the second. True, it is a very small basis, but still it is enough to make an induction from; you generalize the facts, and you expect to find sourness in apples where you get hardness and greenness. You found upon that a general law, that all hard and green apples are sour; and that, so far as it goes, is a perfect induction. Well, having got your natural law in this way, when you are offered another apple which you find is hard and green, you say, "All hard and green apples are sour; this apple is hard and green, therefore this apple is sour." That train of reasoning is what logicians call a syllogism, and has all its various parts and terms,--its major premiss, its minor premiss, and its conclusion. And, by the help of further reasoning, which, if drawn out, would have to be exhibited in two or three other syllogisms, you arrive at your final determination, "I will not have that apple." So that, you see, you have, in the first place, established a law by Induction, and upon that you have founded a Deduction, and reasoned out the special conclusion of the particular case. Well now, suppose, having got your law, that at some time afterwards, you are discussing the qualities of apples with a friend: you will say to him, "It is a very curious thing,--but I find that all hard and green apples are sour!" Your friend says to you, "But how do you know that?" You at once reply, "Oh, because I have tried it over and over again, and have always found them to be so." Well, if we were talking science instead of common sense, we should call that an Experimental Verification. And, if still opposed, you go further, and say, "I have heard from the people in Somersetshire and Devonshire, where a large number of apples are grown, that they have observed the same thing. It is also found to be the case in Normandy, and in North America. In short, I find it to be the universal experience of mankind wherever attention has been directed to the subject." Whereupon, your friend, unless he is a very unreasonable man, agrees with you, and is convinced that you are quite right in the conclusion you have drawn. He believes, although perhaps he does not know he believes it, that the more extensive Verifications are,--that the more frequently experiments have been made, and results of the same kind arrived at,--that the more varied the conditions under which the same results have been attained, the more certain is the ultimate conclusion, and he disputes the question no further. He sees that the experiment has been tried under all sorts of conditions, as to time, place, and people, with the same result; and he says with you, therefore, that the law you have laid down must be a good one, and he must believe it. In science we do the same thing;--the philosopher exercises precisely the same faculties, though in a much more delicate manner. In scientific inquiry it becomes a matter of duty to expose a supposed law to every possible kind of verification, and to take care, moreover, that this is done intentionally, and not left to a mere accident, as in the case of the apples. And in science, as in common life, our confidence in a law is in exact proportion to the absence of variation in the result of our experimental verifications. For instance, if you let go your grasp of an article you may have in your hand, it will immediately fall to the ground. That is a very common verification of one of the best established laws of nature--that of gravitation. The method by which men of science establish the existence of that law is exactly the same as that by which we have established the trivial proposition about the sourness of hard and green apples. But we believe it in such an extensive, thorough, and unhesitating manner because the universal experience of mankind verifies it, and we can verify it ourselves at any time; and that is the strongest possible foundation on which any natural law can rest. So much by way of proof that the method of establishing laws in science is exactly the same as that pursued in common life. Let us now turn to another matter (though really it is but another phase of the same question), and that is, the method by which, from the relations of certain phenomena, we prove that some stand in the position of causes towards the others. I want to put the case clearly before you, and I will therefore show you what I mean by another familiar example. I will suppose that one of you, on coming down in the morning to the parlour of your house, finds that a tea-pot and some spoons which had been left in the room on the previous evening are gone,--the window is open, and you observe the mark of a dirty hand on the window-frame, and perhaps, in addition to that, you notice the impress of a hob-nailed shoe on the gravel outside. All these phenomena have struck your attention instantly, and before two minutes have passed you say, "Oh, somebody has broken open the window, entered the room, and run off with the spoons and the tea-pot!" That speech is out of your mouth in a moment. And you will probably add, "I know there has; I am quite sure of it!" You mean to say exactly what you know; but in reality what you have said has been the expression of what is, in all essential particulars, an Hypothesis. You do not 'know' it at all; it is nothing but an hypothesis rapidly framed in your own mind! And it is an hypothesis founded on a long train of inductions and deductions. What are those inductions and deductions, and how have you got at this hypothesis? You have observed, in the first place, that the window is open; but by a train of reasoning involving many Inductions and Deductions, you have probably arrived long before at the General Law--and a very good one it is--that windows do not open of themselves; and you therefore conclude that something has opened the window. A second general law that you have arrived at in the same way is, that tea-pots and spoons do not go out of a window spontaneously, and you are satisfied that, as they are not now where you left them, they have been removed. In the third place, you look at the marks on the window-sill, and the shoemarks outside, and you say that in all previous experience the former kind of mark has never been produced by anything else but the hand of a human being; and the same experience shows that no other animal but man at present wears shoes with hob-nails on them such as would produce the marks in the gravel. I do not know, even if we could discover any of those "missing links" that are talked about, that they would help us to any other conclusion! At any rate the law which states our present experience is strong enough for my present purpose.--You next reach the conclusion, that as these kinds of marks have not been left by any other animals than men, or are liable to be formed in any other way than by a man's hand and shoe, the marks in question have been formed by a man in that way. You have, further, a general law, founded on observation and experience, and that, too, is, I am sorry to say, a very universal and unimpeachable one,--that some men are thieves; and you assume at once from all these premisses--and that is what constitutes your hypothesis--that the man who made the marks outside and on the window-sill, opened the window, got into the room, and stole your tea-pot and spoons. You have now arrived at a 'Vera Causa';--you have assumed a Cause which it is plain is competent to produce all the phenomena you have observed. You can explain all these phenomena only by the hypothesis of a thief. But that is a hypothetical conclusion, of the justice of which you have no absolute proof at all; it is only rendered highly probable by a series of inductive and deductive reasonings. I suppose your first action, assuming that you are a man of ordinary common sense, and that you have established this hypothesis to your own satisfaction, will very likely be to go off for the police, and set them on the track of the burglar, with the view to the recovery of your property. But just as you are starting with this object, some person comes in, and on learning what you are about, says, "My good friend, you are going on a great deal too fast. How do you know that the man who really made the marks took the spoons? It might have been a monkey that took them, and the man may have merely looked in afterwards." You would probably reply, "Well, that is all very well, but you see it is contrary to all experience of the way tea-pots and spoons are abstracted; so that, at any rate, your hypothesis is less probable than mine." While you are talking the thing over in this way, another friend arrives, one of that good kind of people that I was talking of a little while ago. And he might say, "Oh, my dear sir, you are certainly going on a great deal too fast. You are most presumptuous. You admit that all these occurrences took place when you were fast asleep, at a time when you could not possibly have known anything about what was taking place. How do you know that the laws of Nature are not suspended during the night? It may be that there has been some kind of supernatural interference in this case." In point of fact, he declares that your hypothesis is one of which you cannot at all demonstrate the truth, and that you are by no means sure that the laws of Nature are the same when you are asleep as when you are awake. Well, now, you cannot at the moment answer that kind of reasoning. You feel that your worthy friend has you somewhat at a disadvantage. You will feel perfectly convinced in your own mind, however, that you are quite right, and you say to him, "My good friend, I can only be guided by the natural probabilities of the case, and if you will be kind enough to stand aside and permit me to pass, I will go and fetch the police." Well, we will suppose that your journey is successful, and that by good luck you meet with a policeman; that eventually the burglar is found with your property on his person, and the marks correspond to his hand and to his boots. Probably any jury would consider those facts a very good experimental verification of your hypothesis, touching the cause of the abnormal phenomena observed in your parlour, and would act accordingly. Now, in this suppositious case, I have taken phenomena of a very common kind, in order that you might see what are the different steps in an ordinary process of reasoning, if you will only take the trouble to analyse it carefully. All the operations I have described, you will see, are involved in the mind of any man of sense in leading him to a conclusion as to the course he should take in order to make good a robbery and punish the offender. I say that you are led, in that case, to your conclusion by exactly the same train of reasoning as that which a man of science pursues when he is endeavouring to discover the origin and laws of the most occult phenomena. The process is, and always must be, the same; and precisely the same mode of reasoning was employed by Newton and Laplace in their endeavours to discover and define the causes of the movements of the heavenly bodies, as you, with your own common sense, would employ to detect a burglar. The only difference is, that the nature of the inquiry being more abstruse, every step has to be most carefully watched, so that there may not be a single crack or flaw in your hypothesis. A flaw or crack in many of the hypotheses of daily life may be of little or no moment as affecting the general correctness of the conclusions at which we may arrive; but, in a scientific inquiry, a fallacy, great or small, is always of importance, and is sure to be constantly productive of mischievous, if not fatal results. Do not allow yourselves to be misled by the common notion that an hypothesis is untrustworthy simply because it is an hypothesis. It is often urged, in respect to some scientific conclusion, that, after all, it is only an hypothesis. But what more have we to guide us in nine-tenths of the most important affairs of daily life than hypotheses, and often very ill-based ones? So that in science, where the evidence of an hypothesis is subjected to the most rigid examination, we may rightly pursue the same course. You may have hypotheses and hypotheses. A man may say, if he likes, that the moon is made of green cheese: that is an hypothesis. But another man, who has devoted a great deal of time and attention to the subject, and availed himself of the most powerful telescopes and the results of the observations of others, declares that in his opinion it is probably composed of materials very similar to those of which our own earth is made up: and that is also only an hypothesis. But I need not tell you that there is an enormous difference in the value of the two hypotheses. That one which is based on sound scientific knowledge is sure to have a corresponding value; and that which is a mere hasty random guess is likely to have but little value. Every great step in our progress in discovering causes has been made in exactly the same way as that which I have detailed to you. A person observing the occurrence of certain facts and phenomena asks, naturally enough, what process, what kind of operation known to occur in nature applied to the particular case, will unravel and explain the mystery? Hence you have the scientific hypothesis; and its value will be proportionate to the care and completeness with which its basis had been tested and verified. It is in these matters as in the commonest affairs of practical life: the guess of the fool will be folly, while the guess of the wise man will contain wisdom. In all cases, you see that the value of the result depends on the patience and faithfulness with which the investigator applies to his hypothesis every possible kind of verification. I dare say I may have to return to this point by-and-by; but having dealt thus far with our logical methods, I must now turn to something which, perhaps, you may consider more interesting, or, at any rate, more tangible. But in reality there are but few things that can be more important for you to understand than the mental processes and the means by which we obtain scientific conclusions and theories. [1] Having granted that the inquiry is a proper one, and having determined on the nature of the methods we are to pursue and which only can lead to success, I must now turn to the consideration of our knowledge of the nature of the processes which have resulted in the present condition of organic nature. Here, let me say at once, lest some of you misunderstand me, that I have extremely little to report. The question of how the present condition of organic nature came about, resolves itself into two questions. The first is: How has organic or living matter commenced its existence? And the second is: How has it been perpetuated? On the second question I shall have more to say hereafter. But on the first one, what I now have to say will be for the most part of a negative character. If you consider what kind of evidence we can have upon this matter, it will resolve itself into two kinds. We may have historical evidence and we may have experimental evidence. It is, for example, conceivable, that inasmuch as the hardened mud which forms a considerable portion of the thickness of the earth's crust contains faithful records of the past forms of life, and inasmuch as these differ more and more as we go further down,--it is possible and conceivable that we might come to some particular bed or stratum which should contain the remains of those creatures with which organic life began upon the earth. And if we did so, and if such forms of organic life were preservable, we should have what I would call historical evidence of the mode in which organic life began upon this planet. Many persons will tell you, and indeed you will find it stated in many works on geology, that this has been done, and that we really possess such a record; there are some who imagine that the earliest forms of life of which we have as yet discovered any record, are in truth the forms in which animal life began upon the globe. The grounds on which they base that supposition are these:--That if you go through the enormous thickness of the earth's crust and get down to the older rocks, the higher vertebrate animals--the quadrupeds, birds, and fishes--cease to be found; beneath them you find only the invertebrate animals; and in the deepest and lowest rocks those remains become scantier and scantier, not in any very gradual progression, however, until, at length, in what are supposed to be the oldest rocks, the animal remains which are found are almost always confined to four forms--'Oldhamia', whose precise nature is not known, whether plant or animal; 'Lingula', a kind of mollusc; 'Trilobites', a crustacean animal, having the same essential plan of construction, though differing in many details from a lobster or crab; and Hymenocaris, which is also a crustacean. So that you have all the 'Fauna' reduced, at this period, to four forms: one a kind of animal or plant that we know nothing about, and three undoubted animals--two crustaceans and one mollusc. I think, considering the organization of these mollusca and crustacea, and looking at their very complex nature, that it does indeed require a very strong imagination to conceive that these were the first created of all living things. And you must take into consideration the fact that we have not the slightest proof that these which we call the oldest beds are really so: I repeat, we have not the slightest proof of it. When you find in some places that in an enormous thickness of rocks there are but very scanty traces of life, or absolutely none at all; and that in other parts of the world rocks of the very same formation are crowded with the records of living forms, I think it is impossible to place any reliance on the supposition, or to feel oneself justified in supposing that these are the forms in which life first commenced. I have not time here to enter upon the technical grounds upon which I am led to this conclusion,--that could hardly be done properly in half a dozen lectures on that part alone;--I must content myself with saying that I do not at all believe that these are the oldest forms of life. I turn to the experimental side to see what evidence we have there. To enable us to say that we know anything about the experimental origination of organization and life, the investigator ought to be able to take inorganic matters, such as carbonic acid, ammonia, water, and salines, in any sort of inorganic combination, and be able to build them up into Protein matter, and that that Protein matter ought to begin to live in an organic form. That, nobody has done as yet, and I suspect it will be a long while before anybody does do it. But the thing is by no means so impossible as it looks; for the researches of modern chemistry have shown us--I won't say the road towards it, but, if I may so say, they have shown the finger-post pointing to the road that may lead to it. It is not many years ago--and you must recollect that Organic Chemistry is a young science, not above a couple of generations old,--you must not expect too much of it; it is not many years ago since it was said to be perfectly impossible to fabricate any organic compound; that is to say, any non-mineral compound which is to be found in an organized being. It remained so for a very long period; but it is now a considerable number of years since a distinguished foreign chemist contrived to fabricate Urea, a substance of a very complex character, which forms one of the waste products of animal structures. And of late years a number of other compounds, such as Butyric Acid, and others, have been added to the list. I need not tell you that chemistry is an enormous distance from the goal I indicate; all I wish to point out to you is, that it is by no means safe to say that that goal may not be reached one day. It may be that it is impossible for us to produce the conditions requisite to the origination of life; but we must speak modestly about the matter, and recollect that Science has put her foot upon the bottom round of the ladder. Truly he would be a bold man who would venture to predict where she will be fifty years hence. There is another inquiry which bears indirectly upon this question, and upon which I must say a few words. You are all of you aware of the phenomena of what is called spontaneous generation. Our forefathers, down to the seventeenth century, or thereabouts, all imagined, in perfectly good faith, that certain vegetable and animal forms gave birth, in the process of their decomposition, to insect life. Thus, if you put a piece of meat in the sun, and allowed it to putrefy, they conceived that the grubs which soon began to appear were the result of the action of a power of spontaneous generation which the meat contained. And they could give you receipts for making various animal and vegetable preparations which would produce particular kinds of animals. A very distinguished Italian naturalist, named Redi, took up the question, at a time when everybody believed in it; among others our own great Harvey, the discoverer of the circulation of the blood. You will constantly find his name quoted, however, as an opponent of the doctrine of spontaneous generation; but the fact is, and you will see it if you will take the trouble to look into his works, Harvey believed it as profoundly as any man of his time; but he happened to enunciate a very curious proposition--that every living thing came from an 'egg'; he did not mean to use the word in the sense in which we now employ it, he only meant to say that every living thing originated in a little rounded particle of organized substance; and it is from this circumstance, probably, that the notion of Harvey having opposed the doctrine originated. Then came Redi, and he proceeded to upset the doctrine in a very simple manner. He merely covered the piece of meat with some very fine gauze, and then he exposed it to the same conditions. The result of this was that no grubs or insects were produced; he proved that the grubs originated from the insects who came and deposited their eggs in the meat, and that they were hatched by the heat of the sun. By this kind of inquiry he thoroughly upset the doctrine of spontaneous generation, for his time at least. Then came the discovery and application of the microscope to scientific inquiries, which showed to naturalists that besides the organisms which they already knew as living beings and plants, there were an immense number of minute things which could be obtained apparently almost at will from decaying vegetable and animal forms. Thus, if you took some ordinary black pepper or some hay, and steeped it in water, you would find in the course of a few days that the water had become impregnated with an immense number of animalcules swimming about in all directions. From facts of this kind naturalists were led to revive the theory of spontaneous generation. They were headed here by an English naturalist,--Needham,--and afterwards in France by the learned Buffon. They said that these things were absolutely begotten in the water of the decaying substances out of which the infusion was made. It did not matter whether you took animal or vegetable matter, you had only to steep it in water and expose it, and you would soon have plenty of animalcules. They made an hypothesis about this which was a very fair one. They said, this matter of the animal world, or of the higher plants, appears to be dead, but in reality it has a sort of dim life about it, which, if it is placed under fair conditions, will cause it to break up into the forms of these little animalcules, and they will go through their lives in the same way as the animal or plant of which they once formed a part. The question now became very hotly debated. Spallanzani, an Italian naturalist, took up opposite views to those of Needham and Buffon, and by means of certain experiments he showed that it was quite possible to stop the process by boiling the water, and closing the vessel in which it was contained. "Oh!" said his opponents; "but what do you know you may be doing when you heat the air over the water in this way? You may be destroying some property of the air requisite for the spontaneous generation of the animalcules." However, Spallanzani's views were supposed to be upon the right side, and those of the others fell into discredit; although the fact was that Spallanzani had not made good his views. Well, then, the subject continued to be revived from time to time, and experiments were made by several persons; but these experiments were not altogether satisfactory. It was found that if you put an infusion in which animalcules would appear if it were exposed to the air into a vessel and boiled it, and then sealed up the mouth of the vessel, so that no air, save such as had been heated to 212 degrees, could reach its contents, that then no animalcules would be found; but if you took the same vessel and exposed the infusion to the air, then you would get animalcules. Furthermore, it was found that if you connected the mouth of the vessel with a red-hot tube in such a way that the air would have to pass through the tube before reaching the infusion, that then you would get no animalcules. Yet another thing was noticed: if you took two flasks containing the same kind of infusion, and left one entirely exposed to the air, and in the mouth of the other placed a ball of cotton wool, so that the air would have to filter itself through it before reaching the infusion, that then, although you might have plenty of animalcules in the first flask, you would certainly obtain none from the second. These experiments, you see, all tended towards one conclusion--that the infusoria were developed from little minute spores or eggs which were constantly floating in the atmosphere, which lose their power of germination if subjected to heat. But one observer now made another experiment which seemed to go entirely the other way, and puzzled him altogether. He took some of this boiled infusion that I have been speaking of, and by the use of a mercurial bath--a kind of trough used in laboratories--he deftly inverted a vessel containing the infusion into the mercury, so that the latter reached a little beyond the level of the mouth of the 'inverted' vessel. You see that he thus had a quantity of the infusion shut off from any possible communication with the outer air by being inverted upon a bed of mercury. He then prepared some pure oxygen and nitrogen gases, and passed them by means of a tube going from the outside of the vessel, up through the mercury into the infusion; so that he thus had it exposed to a perfectly pure atmosphere of the same constituents as the external air. Of course, he expected he would get no infusorial animalcules at all in that infusion; but, to his great dismay and discomfiture, he found he almost always did get them. Furthermore, it has been found that experiments made in the manner described above answer well with most infusions; but that if you fill the vessel with boiled milk, and then stop the neck with cotton-wool, you 'will' have infusoria. So that you see there were two experiments that brought you to one kind of conclusion, and three to another; which was a most unsatisfactory state of things to arrive at in a scientific inquiry. Some few years after this, the question began to be very hotly discussed in France. There was M. Pouchet, a professor at Rouen, a very learned man, but certainly not a very rigid experimentalist. He published a number of experiments of his own, some of which were very ingenious, to show that if you went to work in a proper way, there was a truth in the doctrine of spontaneous generation. Well, it was one of the most fortunate things in the world that M. Pouchet took up this question, because it induced a distinguished French chemist, M. Pasteur, to take up the question on the other side; and he has certainly worked it out in the most perfect manner. I am glad to say, too, that he has published his researches in time to enable me to give you an account of them. He verified all the experiments which I have just mentioned to you--and then finding those extraordinary anomalies, as in the case of the mercury bath and the milk, he set himself to work to discover their nature. In the case of milk he found it to be a question of temperature. Milk in a fresh state is slightly alkaline; and it is a very curious circumstance, but this very slight degree of alkalinity seems to have the effect of preserving the organisms which fall into it from the air from being destroyed at a temperature of 212 degrees, which is the boiling point. But if you raise the temperature 10 degrees when you boil it, the milk behaves like everything else; and if the air with which it comes in contact, after being boiled at this temperature, is passed through a red-hot tube, you will not get a trace of organisms. He then turned his attention to the mercury bath, and found on examination that the surface of the mercury was almost always covered with a very fine dust. He found that even the mercury itself was positively full of organic matters; that from being constantly exposed to the air, it had collected an immense number of these infusorial organisms from the air. Well, under these circumstances he felt that the case was quite clear, and that the mercury was not what it had appeared to M. Schwann to be,--a bar to the admission of these organisms; but that, in reality, it acted as a reservoir from which the infusion was immediately supplied with the large quantity that had so puzzled him. But not content with explaining the experiments of others, M. Pasteur went to work to satisfy himself completely. He said to himself: "If my view is right, and if, in point of fact, all these appearances of spontaneous generation are altogether due to the falling of minute germs suspended in the atmosphere,--why, I ought not only to be able to show the germs, but I ought to be able to catch and sow them, and produce the resulting organisms." He, accordingly, constructed a very ingenious apparatus to enable him to accomplish this trapping of this "germ dust" in the air. He fixed in the window of his room a glass tube, in the centre of which he had placed a ball of gun-cotton, which, as you all know, is ordinary cotton-wool, which, from having been steeped in strong acid, is converted into a substance of great explosive power. It is also soluble in alcohol and ether. One end of the glass tube was, of course, open to the external air; and at the other end of it he placed an aspirator, a contrivance for causing a current of the external air to pass through the tube. He kept this apparatus going for four-and-twenty hours, and then removed the 'dusted' gun-cotton, and dissolved it in alcohol and ether. He then allowed this to stand for a few hours, and the result was, that a very fine dust was gradually deposited at the bottom of it. That dust, on being transferred to the stage of a microscope, was found to contain an enormous number of starch grains. You know that the materials of our food and the greater portion of plants are composed of starch, and we are constantly making use of it in a variety of ways, so that there is always a quantity of it suspended in the air. It is these starch grains which form many of those bright specks that we see dancing in a ray of light sometimes. But besides these, M. Pasteur found also an immense number of other organic substances such as spores of fungi, which had been floating about in the air and had got caged in this way. He went farther, and said to himself, "If these really are the things that give rise to the appearance of spontaneous generation, I ought to be able to take a ball of this 'dusted' gun-cotton and put it into one of my vessels, containing that boiled infusion which has been kept away from the air, and in which no infusoria are at present developed, and then, if I am right, the introduction of this gun-cotton will give rise to organisms." Accordingly, he took one of these vessels of infusion, which had been kept eighteen months, without the least appearance of life, and by a most ingenious contrivance, he managed to break it open and introduce such a ball of gun-cotton, without allowing the infusion or the cotton ball to come into contact with any air but that which had been subjected to a red heat, and in twenty-four hours he had the satisfaction of finding all the indications of what had been hitherto called spontaneous generation. He had succeeded in catching the germs and developing organisms in the way he had anticipated. It now struck him that the truth of his conclusions might be demonstrated without all the apparatus he had employed. To do this, he took some decaying animal or vegetable substance, such as urine, which is an extremely decomposable substance, or the juice of yeast, or perhaps some other artificial preparation, and filled a vessel having a long tubular neck with it. He then boiled the liquid and bent that long neck into an S shape or zig-zag, leaving it open at the end. The infusion then gave no trace of any appearance of spontaneous generation, however long it might be left, as all the germs in the air were deposited in the beginning of the bent neck. He then cut the tube close to the vessel, and allowed the ordinary air to have free and direct access; and the result of that was the appearance of organisms in it, as soon as the infusion had been allowed to stand long enough to allow of the growth of those it received from the air, which was about forty-eight hours. The result of M. Pasteur's experiments proved, therefore, in the most conclusive manner, that all the appearances of spontaneous generation arose from nothing more than the deposition of the germs of organisms which were constantly floating in the air. To this conclusion, however, the objection was made, that if that were the cause, then the air would contain such an enormous number of these germs, that it would be a continual fog. But M. Pasteur replied that they are not there in anything like the number we might suppose, and that an exaggerated view has been held on that subject; he showed that the chances of animal or vegetable life appearing in infusions, depend entirely on the conditions under which they are exposed. If they are exposed to the ordinary atmosphere around us, why, of course, you may have organisms appearing early. But, on the other hand, if they are exposed to air from a great height, or from some very quiet cellar, you will often not find a single trace of life. So that M. Pasteur arrived at last at the clear and definite result, that all these appearances are like the case of the worms in the piece of meat, which was refuted by Redi, simply germs carried by the air and deposited in the liquids in which they afterwards appear. For my own part, I conceive that, with the particulars of M. Pasteur's experiments before us, we cannot fail to arrive at his conclusions; and that the doctrine of spontaneous generation has received a final 'coup de grace'. You, of course, understand that all this in no way interferes with the 'possibility' of the fabrication of organic matters by the direct method to which I have referred, remote as that possibility may be. [Footnote 1: Those who wish to study fully the doctrines of which I have endeavoured to give some rough and ready illustrations, must read Mr. John Stuart Mill's 'System of Logic'.] 
23427	----	Evolution, Old & New "The want of a practical acquaintance with Natural History leads the author to take an erroneous view of the bearing of his own theories on those of Mr. Darwin.--_Review of 'Life and Habit,' by Mr. A. R. Wallace, in 'Nature,' March 27, 1879._ "Neither lastly would our observer be driven out of his conclusion, or from his confidence in its truth, by being told that he knows nothing at all about the matter. He knows enough for his argument; he knows the utility of the end; he knows the subserviency and adaptation of the means to the end. These points being known, his ignorance concerning other points, his doubts concerning other points, affect not the certainty of his reasoning. The consciousness of knowing little need not beget a distrust of that which he does know." Paley's '_Natural Theology_,' chap. i. Evolution, Old & New Or the Theories of Buffon, Dr. Erasmus Darwin and Lamarck, as compared with that of Charles Darwin _by_ Samuel Butler New York E. P. Dutton & Company 681 Fifth Avenue _Made and printed in Great Britain_ NOTE The demand for a new edition of "Evolution, Old and New," gives me an opportunity of publishing Butler's latest revision of his work. The second edition of "Evolution, Old and New," which was published in 1882 and re-issued with a new title-page in 1890, was merely a re-issue of the first edition with a new preface, an appendix, and an index. At a later date, though I cannot say precisely when, Butler revised the text of the book in view of a future edition. The corrections that he made are mainly verbal and do not, I think, affect the argument to any considerable extent. Butler, however, attached sufficient importance to them to incur the expense of having the stereos of more than fifty pages cancelled and new stereos substituted. I have also added a few entries to the index, which are taken from a copy of the book, now in my possession, in which Butler made a few manuscript notes. R. A. STREATFEILD. _October, 1911._ AUTHOR'S PREFACE TO THE SECOND EDITION Since the proof-sheets of the Appendix to this book left my hands, finally corrected, and too late for me to be able to recast the first of the two chapters that compose it, I hear, with the most profound regret, of the death of Mr. Charles Darwin. It being still possible for me to refer to this event in a preface, I hasten to say how much it grates upon me to appear to renew my attack upon Mr. Darwin under the present circumstances. I have insisted in each of my three books on Evolution upon the immensity of the service which Mr. Darwin rendered to that transcendently important theory. In "Life and Habit," I said: "To the end of time, if the question be asked, 'Who taught people to believe in Evolution?' the answer must be that it was Mr. Darwin." This is true; and it is hard to see what palm of higher praise can be awarded to any philosopher. I have always admitted myself to be under the deepest obligations to Mr. Darwin's works; and it was with the greatest reluctance, not to say repugnance, that I became one of his opponents. I have partaken of his hospitality, and have had too much experience of the charming simplicity of his manner not to be among the readiest to at once admire and envy it. It is unfortunately true that I believe Mr. Darwin to have behaved badly to me; this is too notorious to be denied; but at the same time I cannot be blind to the fact that no man can be judge in his own case, and that after all Mr. Darwin may have been right, and I wrong. At the present moment, let me impress this latter alternative upon my mind as far as possible, and dwell only upon that side of Mr. Darwin's work and character, about which there is no difference of opinion among either his admirers or his opponents. _April 21, 1882._ PREFACE. Contrary to the advice of my friends, who caution me to avoid all appearance of singularity, I venture upon introducing a practice, the expediency of which I will submit to the judgment of the reader. It is one which has been adopted by musicians for more than a century--to the great convenience of all who are fond of music--and I observe that within the last few years two such distinguished painters as Mr. Alma-Tadema and Mr. Hubert Herkomer have taken to it. It is a matter for regret that the practice should not have been general at an earlier date, not only among painters and musicians, but also among the people who write books. It consists in signifying the number of a piece of music, picture, or book by the abbreviation "Op." and the number whatever it may happen to be. No work can be judged intelligently unless not only the author's relations to his surroundings, but also the relation in which the work stands to the life and other works of the author, is understood and borne in mind; nor do I know any way of conveying this information at a glance, comparable to that which I now borrow from musicians. When we see the number against a work of Beethoven, we need ask no further to be informed concerning the general character of the music. The same holds good more or less with all composers. Handel's works were not numbered--not at least his operas and oratorios. Had they been so, the significance of the numbers on Susanna and Theodora would have been at once apparent, connected as they would have been with the number on Jephthah, Handel's next and last work, in which he emphatically repudiates the influence which, perhaps in a time of self-distrust, he had allowed contemporary German music to exert over him. Many painters have dated their works, but still more have neglected doing so, and some of these have been not a little misconceived in consequence. As for authors, it is unnecessary to go farther back than Lord Beaconsfield, Thackeray, Dickens, and Scott, to feel how much obliged we should have been to any custom that should have compelled them to number their works in the order in which they were written. When we think of Shakespeare, any doubt which might remain as to the advantage of the proposed innovation is felt to disappear. My friends, to whom I urged all the above, and more, met me by saying that the practice was doubtless a very good one in the abstract, but that no one was particularly likely to want to know in what order my books had been written. To which I answered that even a bad book which introduced so good a custom would not be without value, though the value might lie in the custom, and not in the book itself; whereon, seeing that I was obstinate, they left me, and interpreting their doing so into at any rate a modified approbation of my design, I have carried it into practice. The edition of the 'Philosophie Zoologique' referred to in the following volume, is that edited by M. Chas. Martins, Paris, Librairie F. Savy, 24, Rue de Hautefeuille, 1873. The edition of the 'Origin of Species' is that of 1876, unless another edition be especially named. The italics throughout the book are generally mine, except in the quotations from Miss Seward, where they are all her own. I am anxious also to take the present opportunity of acknowledging the obligations I am under to my friend Mr. H. F. Jones, and to other friends (who will not allow me to mention their names, lest more errors should be discovered than they or I yet know of), for the invaluable assistance they have given me while this work was going through the press. If I am able to let it go before the public with any comfort or peace of mind, I owe it entirely to the carefulness of their supervision. I am also greatly indebted to Mr. Garnett, of the British Museum, for having called my attention to many works and passages of which otherwise I should have known nothing. _March 31, 1879._ CONTENTS. CHAPTER I. Statement of the Question--Current Opinion adverse to Teleology 1 CHAPTER II. The Teleology of Paley and the Theologians 12 CHAPTER III. Impotence of Paley's Conclusion--The Teleology of the Evolutionist 24 CHAPTER IV. Failure of the First Evolutionists to see their Position as Teleological 34 CHAPTER V. The Teleological Evolution of Organism--The Philosophy of the Unconscious 43 CHAPTER VI. Scheme of the Remainder of the Work--Historical Sketch of the Theory of Evolution 60 CHAPTER VII. Pre-Buffonian Evolution, and some German Writers 68 CHAPTER VIII. Buffon--Memoir 74 CHAPTER IX. Buffon's Method--The Ironical Character of his Work 78 CHAPTER X. Supposed Fluctuations of Opinion--Causes or Means of the Transformation of Species 97 CHAPTER XI. Buffon--Puller Quotations 107 CHAPTER XII. Sketch of Dr. Erasmus Darwin's Life 173 CHAPTER XIII. Philosophy of Dr. Erasmus Darwin 195 CHAPTER XIV. Fuller Quotations from the 'Zoonomia' 214 CHAPTER XV. Memoir of Lamarck 235 CHAPTER XVI. General Misconception concerning Lamarck--His Philosophical Position 244 CHAPTER XVII. Summary of the 'Philosophie Zoologique' 261 CHAPTER XVIII. Mr. Patrick Matthew, MM. Étienne and Isidore Geoffroy St. Hilaire, and Mr. Herbert Spencer 315 CHAPTER XIX. Main Points of Agreement and of Difference between the Old and New Theories of Evolution 335 CHAPTER XX. Natural Selection considered as a Means of Modification--The Confusion which this Expression occasions 345 CHAPTER XXI. Mr. Darwin's Defence of the Expression, Natural Selection--Professor Mivart and Natural Selection 362 CHAPTER XXII. The Case of the Madeira Beetles as illustrating the Difference between the Evolution of Lamarck and of Mr. Charles Darwin--Conclusion 373 APPENDIX 385 INDEX 409 EVOLUTION, OLD AND NEW CHAPTER I. STATEMENT OF THE QUESTION. CURRENT OPINION ADVERSE TO TELEOLOGY. Of all the questions now engaging the attention of those whose destiny has commanded them to take more or less exercise of mind, I know of none more interesting than that which deals with what is called teleology--that is to say, with design or purpose, as evidenced by the different parts of animals and plants. The question may be briefly stated thus:-- Can we or can we not see signs in the structure of animals and plants, of something which carries with it the idea of contrivance so strongly that it is impossible for us to think of the structure, without at the same time thinking of contrivance, or design, in connection with it? It is my object in the present work to answer this question in the affirmative, and to lead my reader to agree with me, perhaps mainly, by following the history of that opinion which is now supposed to be fatal to a purposive view of animal and vegetable organs. I refer to the theory of evolution or descent with modification. Let me state the question more at large. When we see organs, or living tools--for there is no well-developed organ of any living being which is not used by its possessor as an instrument or tool for the effecting of some purpose which he considers or has considered for his advantage--when we see living tools which are as admirably fitted for the work required of them, as is the carpenter's plane for planing, or the blacksmith's hammer and anvil for the hammering of iron, or the tailor's needle for sewing, what conclusion shall we adopt concerning them? Shall we hold that they must have been designed or contrived, not perhaps by mental processes indistinguishable from those by which the carpenter's saw or the watch has been designed, but still by processes so closely resembling these that no word can be found to express the facts of the case so nearly as the word "design"? That is to say, shall we imagine that they were arrived at by a living mind as the result of scheming and contriving, and thinking (not without occasional mistakes) which of the courses open to it seemed best fitted for the occasion, or are we to regard the apparent connection between such an organ, we will say, as the eye, and the sight which is affected by it, as in no way due to the design or plan of a living intelligent being, but as caused simply by the accumulation, one upon another, of an almost infinite series of small pieces of good fortune? In other words, shall we see something for which, as Professor Mivart has well said, "to us the word 'mind' is the least inadequate and misleading symbol," as having given to the eagle an eyesight which can pierce the sun, but which, in the night is powerless; while to the owl it has given eyes which shun even the full moon, but find a soft brilliancy in darkness? Or shall we deny that there has been any purpose or design in the fashioning of these different kinds of eyes, and see nothing to make us believe that any living being made the eagle's eye out of something which was not an eye nor anything like one, or that this living being implanted this particular eye of all others in the eagle's head, as being most in accordance with the habits of the creature, and as therefore most likely to enable it to live contentedly and leave plenitude of offspring? And shall we then go on to maintain that the eagle's eye was formed little by little by a series of accidental variations, each one of which was thrown for, as it were, with dice? We shall most of us feel that there must have been a little cheating somewhere with these accidental variations before the eagle could have become so great a winner. I believe I have now stated the question at issue so plainly that there can be no mistake about its nature, I will therefore proceed to show as briefly as possible what have been the positions taken in regard to it by our forefathers, by the leaders of opinion now living, and what I believe will be the next conclusion that will be adopted for any length of time by any considerable number of people. In the times of the ancients the preponderance of opinion was in favour of teleology, though impugners were not wanting. Aristotle[1] leant towards a denial of purpose, while Plato[2] was a firm believer in design. From the days of Plato to our own times, there have been but few objectors to the teleological or purposive view of nature. If an animal had an eye, that eye was regarded as something which had been designed in order to enable its owner to see after such fashion as should be most to its advantage. This, however, is now no longer the prevailing opinion either in this country or in Germany. Professor Haeckel holds a high place among the leaders of German philosophy at the present day. He declares a belief in evolution and in purposiveness to be incompatible, and denies purpose in language which holds out little prospect of a compromise. "As soon, in fact," he writes, "as we acknowledge the exclusive activity of the physico-chemical causes in living (organic) bodies as well as in so-called inanimate (inorganic) nature,"--and this is what Professor Haeckel holds we are bound to do if we accept the theory of descent with modification--"we concede exclusive dominion to that view of the universe, which we may designate as _mechanical_, and which is opposed to the teleological conception. If we compare all the ideas of the universe prevalent among different nations at different times, we can divide them all into two sharply contrasted groups--a _causal_ or _mechanical_, and a _teleological_ or _vitalistic_. The latter has prevailed generally in biology until now, and accordingly the animal and vegetable kingdoms have been considered as the products of a creative power, acting for a definite purpose. In the contemplation of every organism, the unavoidable conviction seemed to press itself upon us, that such a wonderful machine, so complicated an apparatus for motion as exists in the organism, could only be produced by a power analogous to, but infinitely more powerful than the power of man in the construction of his machines."[3] A little lower down he continues:-- "_I maintain with regard to_" this "_much talked of 'purpose in nature' that it has no existence but for those persons who observe phenomena in plants and animals in the most superficial manner_. Without going more deeply into the matter, we can see at once that the rudimentary organs are a formidable obstacle to this theory. And, indeed, anyone who makes a really close study of the organization and mode of life of the various animals and plants, ... must necessarily come to the conclusion, that this 'purposiveness' no more exists than the much talked of 'beneficence' of the Creator."[4] Professor Haeckel justly sees no alternative between, upon the one hand, the creation of independent species by a Personal God--by a "Creator," in fact, who "becomes an organism, who designs a plan, reflects upon and varies this plan, and finally forms creatures according to it, as a human architect would construct his building,"[5]--and the denial of all plan or purpose whatever. There can be no question but that he is right here. To talk of a "designer" who has no tangible existence, no organism with which to think, no bodily mechanism with which to carry his purposes into effect; whose design is not design inasmuch as it has to contend with no impediments from ignorance or impotence, and who thus contrives but by a sort of make-believe in which there is no contrivance; who has a familiar name, but nothing beyond a name which any human sense has ever been able to perceive--this is an abuse of words--an attempt to palm off a shadow upon our understandings as though it were a substance. It is plain therefore that there must either be a designer who "becomes an organism, designs a plan, &c.," or that there can be no designer at all and hence no design. We have seen which of these alternatives Professor Haeckel has adopted. He holds that those who accept evolution are bound to reject all "purposiveness." And here, as I have intimated, I differ from him, for reasons which will appear presently. I believe in an organic and tangible designer of every complex structure, for so long a time past, as that reasonable people will be incurious about all that occurred at any earlier time. Professor Clifford, again, is a fair representative of opinions which are finding favour with the majority of our own thinkers. He writes:-- "There are here some words, however, which require careful definition. And first the word purpose. A thing serves a purpose when it is adapted for some end; thus a corkscrew is adapted to the end of extracting corks from bottles, and our lungs are adapted to the end of respiration. We may say that the extraction of corks is the purpose of the corkscrew, and that respiration is the purpose of the lungs, but here we shall have used the word in two different senses. A man made the corkscrew with a purpose in his mind, and he knew and intended that it should be used for pulling out corks. _But nobody made our lungs with a purpose in his mind and intended that they should be used for breathing._ The respiratory apparatus was adapted to its purpose by natural selection, namely, by the gradual preservation of better and better adaptations, and by the killing-off of the worse and imperfect adaptations."[6] No denial of anything like design could be more explicit. For Professor Clifford is well aware that the very essence of the "Natural Selection" theory, is that the variations shall have been mainly accidental and without design of any sort, but that the adaptations of structure to need shall have come about by the accumulation, through natural selection, of any variation that _happened_ to be favourable. It will be my business on a later page not only to show that the lungs are as purposive as the corkscrew, but furthermore that if drawing corks had been a matter of as much importance to us as breathing is, the list of our organs would have been found to comprise one corkscrew at the least, and possibly two, twenty, or ten thousand; even as we see that the trowel without which the beaver cannot plaster its habitation in such fashion as alone satisfies it, is incorporate into the beaver's own body by way of a tail, the like of which is to be found in no other animal. To take a name which carries with it a far greater authority, that of Mr. Charles Darwin. He writes:-- "It is scarcely possible to avoid comparing the eye with a telescope. We know that this instrument has been perfected by the long-continued efforts of the highest human intellects; and we naturally infer that the eye has been formed by a somewhat analogous process. But may not this inference be presumptuous? Have we any right to declare that the Creator works by intellectual powers like those of man?"[7] Here purposiveness is not indeed denied point-blank, but the intention of the author is unmistakable, it is to refer the wonderful result to the gradual accumulation of small accidental improvements which were not due as a rule, if at all, to anything "analogous" to design. "Variation," he says, "will cause the slight alterations;" that is to say, the slight successive variations whose accumulation results in such a marvellous structure as the eye, are caused by--variation; or in other words, they are indefinite, due to nothing that we can lay our hands upon, and therefore certainly not due to design. "Generation," continues Mr. Darwin, "will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement. Let this process go on for millions of years, and during each year on millions of individuals of many kinds; and may we not believe that a living optical instrument might be thus formed as superior to one of glass, as the works of the Creator are to those of man?"[8] The reader will observe that the only skill--and this involves design--supposed by Mr. Darwin to be exercised in the foregoing process, is the "unerring skill" of natural selection. Natural selection, however, is, as he himself tells us, a synonym for the survival of the fittest, which last he declares to be the "more accurate" expression, and to be "sometimes" equally convenient.[9] It is clear then that he only speaks metaphorically when he here assigns "unerring skill" to the fact that the fittest individuals commonly live longest and transmit most offspring, and that he sees no evidence of design in the numerous slight successive "alterations"--or variations--which are "caused by variation." It were easy to multiply quotations which should prove that the denial of "purposiveness" is commonly conceived to be the inevitable accompaniment of a belief in evolution. I will, however, content myself with but one more--from Isidore Geoffroy St. Hilaire. "Whoever," says this author, "holds the doctrine of final causes, will, if he is consistent, hold also that of the immutability of species; and again, the opponent of the one doctrine will oppose the other also."[10] Nothing can be plainer; I believe, however, that even without quotation the reader would have recognized the accuracy of my contention that a belief in the purposiveness or design of animal and vegetable organs is commonly held to be incompatible with the belief that they have all been evolved from one, or at any rate, from not many original, and low, forms of life. Generally, however, as this incompatibility is accepted, it is not unchallenged. From time to time a voice is uplifted in protest, whose tones cannot be disregarded. "I have always felt," says Sir William Thomson, in his address to the British Association, 1871, "that this hypothesis" (natural selection) "does not contain the true theory of evolution, if indeed evolution there has been, in biology. Sir John Herschel, in expressing a favourable judgment on the hypothesis of zoological evolution (with however some reservation in respect to the origin of man), objected to the doctrine of natural selection on the ground that it was too like the Laputan method of making books, and that it did not sufficiently take into account a continually guiding and controlling intelligence. This seems to me a most valuable and instructive criticism. _I feel profoundly convinced that the argument of design has been greatly too much lost sight of in recent zoological speculations._ Reaction against the frivolities of teleology such as are to be found in the notes of the learned commentators on Paley's 'Natural Theology,' has, I believe, had a temporary effect in turning attention from the solid and irrefragable argument so well put forward in that excellent old book. But overpoweringly strong proofs of intelligent and benevolent design lie all around us,"[11] &c. Sir William Thomson goes on to infer that all living beings depend on an ever-acting Creator and Ruler--meaning, I am afraid, a Creator who is not an organism. Here I cannot follow him, but while gladly accepting his testimony to the omnipresence of intelligent design in almost every structure, whether of animal or plant, I shall content myself with observing the manner in which plants and animals act and with the consequences that are legitimately deducible from their action. FOOTNOTES: [1] See note to Mr. Darwin, Historical Sketch, &c., 'Origin of Species, p. xiii. ed. 1876, and Arist. 'Physicæ Auscultationes,' lib. ii. cap. viii. s. 2. [2] See Phædo and Timæus. [3] 'History of Creation,' vol. i. p. 18 (H. S. King and Co., 1876). [4] Ibid. p. 19. [5] 'History of Creation,' vol. i. p. 73 (H. S. King and Co., 1876). [6] 'Fortnightly Review,' new series, vol. xviii. p. 795. [7] 'Origin of Species,' p. 146, ed. 1876. [8] 'Origin of Species,' p. 146, ed. 1876. [9] Page 49. [10] 'Vie et Doctrine scientifique d'Étienne Geoffroy St. Hilaire,' by Isidore Geoffroy St. Hilaire. Paris, 1847, p. 344. [11] Address to the British Association, 1871. CHAPTER II THE TELEOLOGY OF PALEY AND THE THEOLOGIANS. Let us turn for a while to Paley, to whom Sir W. Thomson has referred us. His work should be so well known that an apology is almost due for quoting it, yet I think it likely that at least nine out of ten of my readers will (like myself till reminded of it by Sir W. Thomson's address) have forgotten its existence. "In crossing a heath," says Paley, "suppose I pitched my foot against a stone, and were asked how the stone came to be there; I might possibly answer that for anything I knew to the contrary, it had lain there for ever; nor would it perhaps be very easy to show the absurdity of this answer. But suppose I had found a _watch_ upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of the answer I had before given--that for anything I knew the watch might have been always there. Yet, why should not this answer serve for the watch as well as for the stone? Why is it not as admissible in the second case as in the first? For this reason, and for no other, viz. that when we come to inspect the watch, we perceive (what we could not discover in the stone) that its several parts are framed and put together for a purpose, e. g. that they are so formed and adjusted as to produce motion, and that motion so regulated as to point out the hour of the day: that if the different parts had been differently shaped from what they are, of a different size from what they are, or placed after any other manner, or in any other order, than that in which they are placed, either no motion at all would have been carried on in the machine, or none that would have answered the use which is now served by it. To reckon up a few of the plainest of these parts, and of their offices all tending to one result: we see a cylindrical box containing a coiled elastic spring, which, by its endeavours to relax itself, turns round the box. We next observe a flexible chain (artificially wrought for the sake of flexure) communicating the action of the spring from the box to the fusee. We then find a series of wheels the teeth of which catch in, and apply to each other, conducting the motion from the fusee to the balance, and from the balance to the pointer; and at the same time by the size and shape of those wheels so regulating the motion as to terminate in causing an index, by an equable and measured progression, to pass over a given space in a given time. We take notice that the wheels are made of brass in order to keep them from rust; the springs of steel, no other metal being so elastic; that over the face of the watch there is placed a glass, a material employed on no other part of the work, but in the room of which if there had been any other than a transparent substance, the hour could not have been observed without opening the case. This mechanism being observed, ... the inference, we think, is inevitable that the watch must have had a maker; that there must have existed, at _some time, and at some place or other, an artificer_ or artificers who formed it for the purpose which we find it actually to answer; who comprehended its construction and designed its use."[12] . . . . . . "That an animal is a machine, is a proposition neither correctly true nor wholly false.... I contend that there is a mechanism in animals; that this mechanism is as properly such, as it is in machines made by art; that this mechanism is intelligible and certain; that it is not the less so because it often begins and terminates with something which is not mechanical; that wherever it is intelligible and certain, it demonstrates intention and contrivance, as well in the works of nature as in those of art; and that it is the best demonstration which either can afford."[13] There is only one legitimate inference deducible from these premises if they are admitted as sound, namely, that there must have existed "_at some time, and in some place, an artificer_" who formed the animal mechanism after much the same mental processes of observation, endeavour, successful contrivance, and after a not wholly unlike succession of bodily actions, as those with which a watchmaker has made a watch. Otherwise the conclusion is impotent, and the whole argument becomes a mere juggle of words. "Now, supposing or admitting," continues Paley, "that we know nothing of the proper internal constitution of a gland, or of the mode of its acting upon the blood; then our situation is precisely like that of an unmechanical looker-on who stands by a stocking loom, a corn mill, a carding machine, or a threshing machine, at work, the fabric and mechanism of which, as well as all that passes within, is hidden from his sight by the outside case; or if seen, would be too complicated for his uninformed, uninstructed understanding to comprehend. And what is that situation? This spectator, ignorant as he is, sees at one end a material enter the machine, as unground grain the mill, raw cotton the carding machine, sheaves of unthreshed corn the threshing machine, and when he casts his eye to the other end of the apparatus, he sees the material issuing from it in a new state and what is more, a state manifestly adapted for its future uses: the grain in meal fit for the making of bread, the wool in rovings fit for the spinning into threads, the sheaf in corn fit for the mill. Is it necessary that this man, in order to be convinced that design, that intention, that contrivance has been employed about the machine, should be allowed to pull it to pieces, should be enabled to examine the parts separately, explore their action upon one another, or their operation, whether simultaneous or successive, upon the material which is presented to them? He may long to do this to satisfy his curiosity; he may desire to do it to improve his theoretic knowledge; ... but for the purpose of ascertaining the existence of counsel and design in the formation of the machine, he wants no such intromission or privity. The effect upon the material, the change produced in it, the utility of the change for future applications, abundantly testify, be the concealed part of the machine, or of its construction, what it will, _the hand and agency of a contriver_."[14] This is admirably put, but it will apply to the mechanism of animal and vegetable bodies only, if it is used to show that they too must have had a contriver who has a hand, or something tantamount to one; who does act; who, being a contriver, has what all other contrivers must have, if they are to be called contrivers--a body which can suffer more or less pain or chagrin if the contrivance is unsuccessful. If this is what Paley means, his argument is indeed irrefragable; but if he does not intend this, his words are frivolous, as so clear and acute a reasoner must have perfectly well known. Whether Paley's argument will prove a source of lasting strength to himself or no, is a point which my readers will decide presently; but I am very clear about its usefulness to my own position. I know few writers whom I would willingly quote more largely, or from whom I find it harder to leave off quoting when I have once begun. A few more passages, however, must suffice. "I challenge any man to produce in the joints and pivots of the most complicated or the most flexible machine that ever was contrived, a construction _more artificial_" (here we have it again), "or more evidently artificial than the human neck. Two things were to be done. The head was to have the power of bending forward and backward as in the act of nodding, stooping, looking upwards or downwards; and at the same time of turning itself round upon the body to a certain extent, the quadrant, we will say, or rather perhaps a hundred and twenty degrees of a circle. For these two purposes two distinct contrivances are employed. First the head rests immediately upon the uppermost part of the vertebra, and is united to it by a hinge-joint; upon this joint the head plays freely backward and forward as far either way as is necessary or as the ligaments allow, which was the first thing required. "But then the rotatory motion is thus unprovided for; therefore, secondly, to make the head capable of this a further mechanism is introduced, not between the head and the uppermost bone of the neck, where the hinge is, but between that bone and the next underneath it. It is a mechanism resembling a tenon and mortise. This second or uppermost bone but one has what the anatomists call a process, viz. a projection somewhat similar in size and shape to a tooth, which tooth, entering a corresponding hollow socket in the bone above it, forms a pivot or axle, upon which that upper bone, together with the head which it supports, turns freely in a circle, and as far in the circle as the attached muscles permit the head to turn. Thus are both motions perfect without interfering with each other. When we nod the head we use the hinge-joint, which lies between the head and the first bone of the neck. When we turn the head round, we use the tenon and mortise, which runs between the first bone of the neck and the second. We see the same contrivance and the same principle employed in the frame or mounting of a telescope. It is occasionally requisite that the object end of the instrument be moved up and down as well as horizontally or equatorially. For the vertical motion there is a hinge upon which the telescope plays, for the horizontal or equatorial motion, an axis upon which the telescope and the hinge turn round together. And this is exactly the mechanism which is applied to the action of the head, nor will anyone here doubt of the existence of counsel and design, except it be by that debility of mind which can trust to its own reasonings in nothing."[15] . . . . . . "The patella, or knee-pan, is a curious little bone; in its form and office unlike any other bone in the body. It is circular, the size of a crown-piece, pretty thick, a little convex on both sides, and covered with a smooth cartilage. It lies upon the front of the knee, and the powerful tendons by which the leg is brought forward pass through it (or rather make it a part of their continuation) from their origin in the thigh to their insertion in the tibia. It protects both the tendon and the joint from any injury which either might suffer by the rubbing of one against the other, or by the pressure of unequal surfaces. It also gives to the tendons a very considerable mechanical advantage by altering the line of their direction, and by advancing it farther out of the centre of motion; and this upon the principles of the resolution of force, upon which all machinery is founded. These are its uses. But what is most observable in it is that it appears to be supplemental, as it were, to the frame; added, as it should almost seem, afterwards; not quite necessary, but very convenient. It is separate from the other bones; that is, it is not connected with any other bones by the common mode of union. It is soft, or hardly formed in infancy; and is produced by an ossification, of the inception or progress of which no account can be given from the structure or exercise of the part."[16] It is positively painful to me to pass over Paley's description of the joints, but I must content myself with a single passage from this admirable chapter. "The joints, or rather the ends of the bones which form them, display also in their configuration another use. The nerves, blood-vessels, and tendons which are necessary to the life, or for the motion of the limbs, must, it is evident in their way from the trunk of the body to the place of their destination, travel over the moveable joints; and it is no less evident that in this part of their course they will have from sudden motions, and from abrupt changes of curvature, to encounter the danger of compression, attrition, or laceration. To guard fibres so tender against consequences so injurious, their path is in those parts protected with peculiar care; and that by a provision in the figure of the bones themselves. The nerves which supply the fore arm, especially the inferior cubital nerves, are at the elbow conducted by a kind of covered way, between the condyle, or rather under the inner extuberances, of the bone which composes the upper part of the arm. At the knee the extremity of the thigh-bone is divided by a sinus or cliff into two heads or protuberances; and these heads on the back part stand out beyond the cylinder of the bone. Through the hollow which lies between the hind parts of these two heads, that is to say, under the ham, between the ham strings, and within the concave recess of the bone formed by the extuberances on either side; in a word, along a defile between rocks pass the great vessels and nerves which go to the leg. Who led these vessels by a road so defended and secured? In the joint at the shoulder, in the edge of the cup which receives the head of the bone, is a notch which is covered at the top with a ligament. Through this hole thus guarded the blood-vessels steal to their destination in the arm instead of mounting over the edge of the concavity."[17] . . . . . . "What contrivance can be more mechanical than the following, viz.: a slit in one tendon to let another tendon pass through it? This structure is found in the tendons which move the toes and fingers. The long tendon, as it is called in the foot, which bends the first joint of the toe, passes through the short tendon which bends the second joint; which course allows to the sinews more liberty and a more commodious action than it would otherwise have been capable of exerting. There is nothing, I believe, in a silk or cotton mill, in the belts or straps or ropes by which the motion is communicated from one part of the machine to another that is more artificial, or more evidently so, than this perforation. "The next circumstance which I shall mention under this head of muscular arrangement, is so decidedly a mark of intention, that it always appeared to me to supersede in some measure the necessity of seeking for any other observation upon the subject; and that circumstance is the tendons which pass from the leg to the foot being bound down by a ligament at the ankle, the foot is placed at a considerable angle with the leg. It is manifest, therefore, that flexible strings passing along the interior of the angle, if left to themselves, would, when stretched, start from it. The obvious" (and it must not be forgotten that the preventive _was_ obvious) "preventive is to tie them down. And this is done in fact. Across the instep, or rather just above it, the anatomist finds a strong ligament, under which the tendons pass to the foot. The effect of the ligament as a bandage can be made evident to the senses, for if it be cut the tendons start up. The simplicity, yet the clearness of this contrivance, its exact resemblance to established resources of art, place it amongst the most indubitable manifestations of design with which we are acquainted." Then follows a passage which is interesting, as being the earliest attempt I know of to bring forward an argument against evolution, which was, even in Paley's day, called "Darwinism," after Dr. Erasmus Darwin its propounder.[18] The argument, I mean, which is drawn from the difficulty of accounting for the incipiency of complex structures. This has been used with greater force by the Rev. J. J. Murphy, Professor Mivart, and others, against that (as I believe) erroneous view of evolution which is now generally received as Darwinism. "There is also a further use," says Paley, "to be made of this present example, and that is as it precisely contradicts the opinion, that the parts of animals may have been all formed by what is called appetency, i. e. endeavour, perpetuated and imperceptibly working its effect through an incalculable series of generations. We have here no endeavour, but the reverse of it; a constant resistency and reluctance. The endeavour is all the other way. The pressure of the ligament constrains the tendons; the tendons react upon the pressure of the ligament. It is impossible that the ligament should ever have been generated by the exercise of the tendons, or in the course of that exercise, forasmuch as the force of the tendon perpendicularly resists the fibre which confines it, and is constantly endeavouring not to form but to rupture and displace the threads of which the ligament is composed."[19] This must suffice. "True theories," says M. Flourens, inspired by a passage from Fontenelle, which he proceeds to quote, "true theories make themselves," they are not made, but are born and grow; they cannot be stopped from insisting upon their vitality by anything short of intellectual violence, nor will a little violence only suffice to kill them. "True theories," he continues, "are but the spontaneous mental coming together of facts, which have combined with one another by virtue only of their own natural affinity."[20] When a number of isolated facts, says Fontenelle, take form, group themselves together coherently, and present the mind so vividly with an idea of their interdependence and mutual bearing upon each other, that no matter how violently we tear them asunder they insist on coming together again; then, and not till then, have we a theory. Now I submit that there is hardly one of my readers who can be considered as free from bias or prejudice, who will not feel that the idea of design--or perception by an intelligent living being, of ends to be obtained and of the means of obtaining them--and the idea of the tendons of the foot and of the ligament which binds them down, come together so forcibly, that no matter how strongly Professors Haeckel and Clifford and Mr. Darwin may try to separate them, they are no sooner pulled asunder than they straightway fly together again of themselves. I shall argue, therefore, no further upon this head, but shall assume it as settled, and shall proceed at once to the consideration that next suggests itself. FOOTNOTES: [12] 'Natural Theology,' ch. i. § 1. [13] Ch. vii. [14] Ch. vii. [15] 'Natural Theology.' ch. viii. [16] 'Natural Theology,' ch. viii. [17] 'Natural Theology,' ch. viii. [18] "What!" says Coleridge, in a note on Stillingfleet, to which Mr. Garnett, of the British Museum, has kindly called my attention, "Did Sir Walter Raleigh believe that a male and female ounce (and if so why not two tigers and lions, &c.?) would have produced in course of generations a cat, or a cat a lion? This is Darwinising with a vengeance."--See 'Athenæum,' March 27, 1875, p. 423. [19] 'Natural Theology,' ch. ix. [20] "La vraie théorie n'est que l'enchaînement naturel des faits, qui dès qu'ils sont assez nombreux, se touchent, et se lient, les uns aux autres par leur seule vertu propre."--Flourens, 'Buffon, Hist. de ses Travaux.' Paris, 1844, p. 82. CHAPTER III. IMPOTENCE OF PALEY'S CONCLUSION. THE TELEOLOGY OF THE EVOLUTIONIST. Though the ideas of design, and of the foot, have come together in our minds with sufficient spontaneity, we yet feel that there is a difference--and a wide difference if we could only lay our hands upon it--between the design and manufacture of the ligament and tendons of the foot on the one hand, and on the other the design, manufacture, and combination of artificial strings, pieces of wood, and bandages, whereby a model of the foot might be constructed. If we conceive of ourselves as looking simultaneously upon a real foot, and upon an admirably constructed artificial one, placed by the side of it, the idea of design, and design by an intelligent living being with a body and soul (without which, as has been already insisted on, the use of the word design is delusive), will present itself strongly to our minds in connection both with the true foot, and with the model; but we find another idea asserting itself with even greater strength, namely, that the design of the true foot is far more intricate, and yet is carried into execution in far more masterly manner than that of the model. We not only feel that there is a wider difference between the ability, time, and care which have been lavished on the real foot and upon the model, than there is between the skill and the time taken to produce Westminster Abbey, and that bestowed upon a gingerbread cake stuck with sugar plums so as to represent it, but also that these two objects must have been manufactured on different principles. We do not for a moment doubt that the real foot was designed, but we are so astonished at the dexterity of the designer that we are at a loss for some time to think who could have designed it, where he can live, in what manner he studied, for how long, and by what processes he carried out his design, when matured, into actual practice. Until recently it was thought that there was no answer to many of these questions, more especially to those which bear upon the mode of manufacture. For the last hundred years, however, the importance of a study has been recognized which does actually reveal to us in no small degree the processes by which the human foot is manufactured, so that in the endeavour to lay our hands upon the points of difference between the kind of design with which the foot itself is designed, and the design of the model, we turn naturally to the guidance of those who have made this study their specialty; and a very wide difference does this study, embryology, at once reveal to us. Writing of the successive changes through which each embryo is forced to pass, the late Mr. G. H. Lewes says that "none of these phases have any adaptation to the future state of the animal, but are in positive contradiction to it or are simply purposeless; whereas all show stamped on them the unmistakable characters of _ancestral_ adaptation, and the progressions of organic evolution. What does the fact imply? There is not a single known example of a complex organism which is not developed out of simpler forms. Before it can attain the complex structure which distinguishes it, there must be an evolution of forms similar to those which distinguish the structure of organisms lower in the series. On the hypothesis of a plan which prearranged the organic world, nothing could be more unworthy of a supreme intelligence than this inability to construct an organism at once, without making several previous tentative efforts, undoing to-day what was so carefully done yesterday, and _repeating for centuries the same tentatives in the same succession_. Do not let us blink this consideration. There is a traditional phrase much in vogue among the anthropomorphists, which arose naturally enough from a tendency to take human methods as an explanation of the Divine--a phrase which becomes a sort of argument--'The Great Architect.' But if we are to admit the human point of view, a glance at the facts of embryology must produce very uncomfortable reflections. For what should we say to an architect who was unable, or being able was obstinately unwilling, to erect a palace except by first using his materials in the shape of a hut, then pulling them down and rebuilding them as a cottage, then adding story to story and room to room, _not_ with any reference to the ultimate purposes of the palace, but wholly with reference to the way in which houses were constructed in ancient times? What should we say to the architect who could not form a museum out of bricks and mortar, but was forced to begin as if going to construct a mansion, and after proceeding some way in this direction, altered his plan into a palace, and that again into a museum? Yet this is the sort of succession on which organisms are constructed. The fact has long been familiar; how has it been reconciled with infinite wisdom? Let the following passage answer for a thousand:--'The embryo is nothing like the miniature of the adult. For a long while the body in its entirety and in its details, presents the strangest of spectacles. Day by day and hour by hour, the aspect of the scene changes, and this instability is exhibited by the most essential parts no less than by the accessory parts. One would say that nature feels her way, and only reaches the goal after many times missing the path' (on dirait que la nature tâtonne et ne conduit son oeuvre à bon fin, qu'après s'être souvent trompée)."[21] The above passage does not, I think, affect the evidence for design which we adduced in the preceding chapter. However strange the process of manufacture may appear, when the work comes to be turned out the design is too manifest to be doubted. If the reader were to come upon some lawyer's deed which dealt with matters of such unspeakable intricacy, that it baffled his imagination to conceive how it could ever have been drafted, and if in spite of this he were to find the intricacy of the provisions to be made, exceeded only by the ease and simplicity with which the deed providing for them was found to work in practice; and after this, if he were to discover that the deed, by whomsoever drawn, had nevertheless been drafted upon principles which at first seemed very foreign to any according to which he was in the habit of drafting deeds himself, as for example, that the draftsman had begun to draft a will as a marriage settlement, and so forth--yet an observer would not, I take it, do either of two things. He would not in the face of the result deny the design, making himself judge rather of the method of procedure than of the achievement. Nor yet after insisting in the manner of Paley, on the wonderful proofs of intention and on the exquisite provisions which were to be found in every syllable--thus leading us up to the highest pitch of expectation--would he present us with such an impotent conclusion as that the designer, though a living person and a true designer, was yet immaterial and intangible, a something, in fact, which proves to be a nothing: an omniscient and omnipotent vacuum. Our observer would feel he need not have been at such pains to establish his design if this was to be the upshot of his reasoning. He would therefore admit the design, and by consequence the designer, but would probably ask a little time for reflection before he ventured to say who, or what, or where the designer was. Then gaining some insight into the manner in which the deed had been drawn, he would conclude that the draftsman was a specialist who had had long practice in this particular kind of work, but who now worked almost as it might be said automatically and without consciousness, and found it difficult to depart from a habitual method of procedure. We turn, then, on Paley, and say to him: "We have admitted your design and your designer. Where is he? Show him to us. If you cannot show him to us as flesh and blood, show him as flesh and sap; show him as a living cell; show him as protoplasm. Lower than this we should not fairly go; it is not in the bond or _nexus_ of our ideas that something utterly inanimate and inorganic should scheme, design, contrive, and elaborate structures which can make mistakes: it may elaborate low unerring things, like crystals, but it cannot elaborate those which have the power to err. Nevertheless, we will commit such abuse with our understandings as to waive this point, and we will ask you to show him to us as air which, if it cannot be seen, yet can be felt, weighed, handled, transferred from place to place, be judged by its effects, and so forth; or if this may not be, give us half a grain of hydrogen, diffused through all space and invested with some of the minor attributes of matter; or if you cannot do this, give us an imponderable like electricity, or even the higher mathematics, but give us something or throw off the mask and tell us fairly out that it is your paid profession to hoodwink us on this matter if you can, and that you are but doing your best to earn an honest living." We may fancy Paley as turning the tables upon us and as saying: "But you too have admitted a designer--you too then must mean a designer with a body and soul, who must be somewhere to be found in space, and who must live in time. Where is this your designer? Can you show him more than I can? Can you lay your finger on him and demonstrate him so that a child shall see him and know him, and find what was heretofore an isolated idea concerning him, combine itself instantaneously with the idea of the designer, we will say, of the human foot, so that no power on earth shall henceforth tear those two ideas asunder? Surely if you cannot do this, you too are trifling with words, and abusing your own mind and that of your reader. Where, then, is your designer of man? Who made him? And where, again, is your designer of beasts and birds, of fishes, and of plants?" Our answer is simple enough; it is that we can and do point to a living tangible person with flesh, blood, eyes, nose, ears, organs, senses, dimensions, who did of his own cunning after infinite proof of every kind of hazard and experiment scheme out, and fashion each organ of the human body. This is the person whom we claim as the designer and artificer of that body, and he is the one of all others the best fitted for the task by his antecedents, and his practical knowledge of the requirements of the case--for he is man himself. Not man, the individual of any given generation, but man in the entirety of his existence from the dawn of life onwards to the present moment. In like manner we say that the designer of all organisms is so incorporate with the organisms themselves--so lives, moves, and has its being in those organisms, and is so one with them--they in it, and it in them--that it is more consistent with reason and the common use of words to see the designer of each living form in the living form itself, than to look for its designer in some other place or person. Thus we have a third alternative presented to us. Mr. Charles Darwin and his followers deny design, as having any appreciable share in the formation of organism at all. Paley and the theologians insist on design, but upon a designer outside the universe and the organism. The third opinion is that suggested in the first instance, and carried out to a very high degree of development by Buffon. It was improved, and, indeed, made almost perfect by Dr. Erasmus Darwin, but too much neglected by him after he had put it forward. It was borrowed, as I think we may say with some confidence, from Dr. Darwin by Lamarck, and was followed up by him ardently thenceforth, during the remainder of his life, though somewhat less perfectly comprehended by him than it had been by Dr. Darwin. It is that the design which has designed organisms, has resided within, and been embodied in, the organisms themselves. With but a very little change in the present signification of words, the question resolves itself into this. Shall we see God henceforth as embodied in all living forms; as dwelling in them; as being that power in them whereby they have learnt to fashion themselves, each one according to its ideas of its own convenience, and to make itself not only a microcosm, or little world, but a little unwritten history of the universe from its own point of view into the bargain? From everlasting, in time past, only in so far as life has lasted; invisible, only in so far as the ultimate connection between the will to do and the thing which does is invisible; imperishable, only in so far as life as a whole is imperishable; omniscient and omnipotent, within the limits only of a very long and large experience, but ignorant and impotent in respect of all else--limited in all the above respects, yet even so incalculably vaster than anything that we can conceive? Or shall we see God as we were taught to say we saw him when we were children--as an artificial and violent attempt to combine ideas which fly asunder and asunder, no matter how often we try to force them into combination? "The true mainspring of our existence," says Buffon, "lies not in those muscles, veins, arteries, and nerves, which have been described with so much minuteness, it is to be found in the more hidden forces which are not bounden by the gross mechanical laws which we would fain set over them. Instead of trying to know these forces by their effects, we have endeavoured to uproot even their very idea, so as to banish them utterly from philosophy. But they return to us and with renewed vigour; they return to us in gravitation, in chemical affinity, in the phenomena of electricity, &c. Their existence rests upon the clearest evidence; the omnipresence of their action is indisputable, but that action is hidden away from our eyes, and is a matter of inference only; we cannot actually see them, therefore we find difficulty in admitting that they exist; we wish to judge of everything by its exterior; we imagine that the exterior is the whole, and deeming that it is not permitted us to go beyond it, we neglect all that may enable us to do so."[22] Or may we not say that the unseen parts of God are those deep buried histories, the antiquity and the repeatedness of which go as far beyond that of any habit handed down to us from our earliest protoplasmic ancestor, as the distance of the remotest star in space transcends our distance from the sun? By vivisection and painful introspection we can rediscover many a long buried history--rekindling that sense of novelty in respect of its action, whereby we can alone become aware of it. But there are other remoter histories, and more repeated thoughts and actions, before which we feel so powerless to reawaken fresh interest concerning them, that we give up the attempt in despair, and bow our heads, overpowered by the sense of their immensity. Thus our inability to comprehend God is coextensive with our difficulty in going back upon the past--and our sense of him is a dim perception of our own vast and now inconceivably remote history. FOOTNOTES: [21] Quatrefages, 'Metamorphoses de l'Homme et des Animaux,' 1862, p. 42; G. H. Lewes, 'Physical Basis of Mind,' 1877, p. 83. [22] Tom. ii. p. 486, 1794. CHAPTER IV. FAILURE OF THE FIRST EVOLUTIONISTS TO SEE THEIR POSITION AS TELEOLOGICAL. It follows necessarily from the doctrine of Dr. Erasmus Darwin and Lamarck, if not from that of Buffon himself, that the greater number of organs are as purposive to the evolutionist as to the theologian, and far more intelligibly so. Circumstances, however, prevented these writers from acknowledging this fact to the world, and perhaps even to themselves. Their _crux_ was, as it still is to so many evolutionists, the presence of rudimentary organs, and the processes of embryological development. They would not admit that rudimentary and therefore useless organs were designed by a Creator to take their place once and for ever as part of a scheme whose main idea was, that every animal structure was to serve some useful end in connection with its possessor. This was the doctrine of final causes as then commonly held; in the face of rudimentary organs it was absurd. Buffon was above all things else a plain matter of fact thinker, who refused to go far beyond the obvious. Like all other profound writers, he was, if I may say so, profoundly superficial. He felt that the aim of research does not consist in the knowing this or that, but in the easing of the desire to know or understand more completely--in the peace of mind which passeth all understanding. His was the perfection of a healthy mental organism by which over effort is felt instinctively to be as vicious and contemptible as indolence. He knew this too well to know the grounds of his knowledge, but we smaller people who know it less completely, can see that such felicitous instinctive tempering together of the two great contradictory principles, love of effort and love of ease, has underlain every step of all healthy growth through all conceivable time. Nothing is worth looking at which is seen either too obviously or with too much difficulty. Nothing is worth doing or well done which is not done fairly easily, and some little deficiency of effort is more pardonable than any very perceptible excess; for virtue has ever erred rather on the side of self-indulgence than of asceticism, and well-being has ever advanced through the pleasures rather than through austerity. According to Buffon, then--as also according to Dr. Darwin, who was just such another practical and genial thinker, and who was distinctly a pupil of Buffon, though a most intelligent and original one--if an organ after a reasonable amount of inspection appeared to be useless, it was to be called useless without more ado, and theories were to be ordered out of court if they were troublesome. In like manner, if animals bred freely _inter se_ before our eyes, as for example the horse and ass, the fact was to be noted, but no animals were to be classed as capable of interbreeding until they had asserted their right to such classification by breeding with tolerable certainty. If, again, an animal looked as if it felt, that is to say, if it moved about pretty quickly or made a noise, it must be held to feel; if it did neither of these things, it did not look as if it felt and therefore it must be said not to feel. _De non apparentibus et non existentibus eadem est lex_ was one of the chief axioms of their philosophy; no writers have had a greater horror of mystery or of ideas that have not become so mastered as to be, or to have been, superficial. Lamarck was one of those men of whom I believe it has been said that they have brain upon the brain. He had his theory that an animal could not feel unless it had a nervous system, and at least a spinal marrow--and that it could not think at all without a brain--all his facts, therefore, have to be made to square with this. With Buffon and Dr. Darwin we feel safe that however wrong they may sometimes be, their conclusions have always been arrived at on that fairly superficial view of things in which, as I have elsewhere said, our nature alone permits us to be comforted. To these writers, then, the doctrine of final causes for rudimentary organs was a piece of mystification and an absurdity; no less fatal to any such doctrine were the processes of embryological development. It was plain that the commonly received teleology must be given up; but the idea of design or purpose was so associated in their minds with theological design that they avoided it altogether. They seem to have forgotten that an internal teleology is as much teleology as an external one; hence, unfortunately, though their whole theory of development is intensely purposive, it is the fact rather than the name of teleology which has hitherto been insisted upon, even by the greatest writers on evolution--the name having been denied even by those who were most insisting on the thing itself. It is easy to understand the difficulty felt by the fathers of evolution when we remember how much had to be seen before the facts could lie well before them. It was necessary to attain, firstly, to a perception of the unity of person between parents and offspring in successive generations; secondly, it must be seen that an organism's memory goes back for generations beyond its birth, to the first beginnings in fact, of which we know anything whatever; thirdly, the latency of that memory, as of memory generally till the associated ideas are reproduced, must be brought to bear upon the facts of heredity; and lastly, the unconsciousness with which habitual actions come to be performed, must be assigned as the explanation of the unconsciousness with which we grow and discharge most of our natural functions. Buffon was too busy with the fact that animals descended with modification at all, to go beyond the development and illustration of this great truth. I doubt whether he ever saw more than the first, and that dimly, of the four considerations above stated. Dr. Darwin was the first to point out the first two considerations with some clearness, but he can hardly be said to have understood their full importance: the two latter ideas do not appear to have occurred to him. Lamarck had little if any perception of any one of the four. When, however, they are firmly seized and brought into their due bearings one upon another, the facts of heredity become as simple as those of a man making a tobacco pipe, and rudimentary organs are seen to be essentially of the same character as the little rudimentary protuberance at the bottom of the pipe to which I referred in 'Erewhon.'[23] These organs are now no longer useful, but they once were so, and were therefore once purposive, though not so now. They are the expressions of a bygone usefulness; sayings, as it were, about which there was at one time infinite wrangling, as to what both the meaning and the expression should best be, so that they then had living significance in the mouths of those who used them, though they have become such mere shibboleths and cant formulæ to ourselves that we think no more of their meaning than we do of Julius Cæsar in the month of July. They continue to be reproduced through the force of habit, and through indisposition to get out of any familiar groove of action until it becomes too unpleasant for us to remain in it any longer. It has long been felt that embryology and rudimentary structures indicated community of descent. Dr. Darwin and Lamarck insisted on this, as have all subsequent writers on evolution; but the explanation of why and how the structures come to be repeated--namely, that they are simply examples of the force of habit--can only be perceived intelligently by those who admit so much unity between parents and offspring that the self-development of the latter can be properly called habitual (as being a repetition of an act by one and the same individual), and can only be fully sympathized with by those who recognize that if habit be admitted as the key to the fact at all, the unconscious manner in which the habit comes to be repeated is only of a piece with all our other observations concerning habit. For the fuller development of the foregoing, I must refer the reader to my work 'Life and Habit.' The purposiveness, which even Dr. Darwin, and Lamarck still less, seem never to have quite recognized in spite of their having insisted so much on what amounts to the same thing, now comes into full view. It is seen that the organs external to the body, and those internal to it are, the second as much as the first, things which we have made for our own convenience, and with a prevision that we shall have need of them; the main difference between the manufacture of these two classes of organs being, that we have made the one kind so often that we can no longer follow the processes whereby we make them, while the others are new things which we must make introspectively or not at all, and which are not yet so incorporate with our vitality as that we should think they grow instead of being manufactured. The manufacture of the tool, and the manufacture of the living organ prove therefore to be but two species of the same genus, which, though widely differentiated, have descended as it were from one common filament of desire and inventive faculty. The greater or less complexity of the organs goes for very little. It is only a question of the amount of intelligence and voluntary self-adaptation which we must admit, and this must be settled rather by an appeal to what we find in organism, and observe concerning it, than by what we may have imagined _à priori_. Given a small speck of jelly with some kind of circumstance-suiting power, some power of slightly varying its actions in accordance with slightly varying circumstances and desires--given such a jelly-speck with a power of assimilating other matter, and thus, of reproducing itself, given also that it should be possessed of a memory, and we can show how the whole animal world can have descended it may be from an amoeba without interference from without, and how every organ in every creature is designed at first roughly and tentatively but finally fashioned with the most consummate perfection, by the creature which has had need of that organ, which best knew what it wanted, and was never satisfied till it had got that which was the best suited to its varying circumstances in their entirety. We can even show how, if it becomes worth the Ethiopian's while to try and change his skin, or the leopard's to change his spots, they can assuredly change them within a not unreasonable time and adapt their covering to their own will and convenience, and to that of none other; thus what is commonly conceived of as direct creation by God is moved back to a time and space inconceivable in their remoteness, while the aim and design so obvious in nature are shown to be still at work around us, growing ever busier and busier, and advancing from day to day both in knowledge and power. It was reserved for Mr. Darwin and for those who have too rashly followed him to deny purpose as having had any share in the development of animal and vegetable organs; to see no evidence of design in those wonderful provisions which have been the marvel and delight of observers in all ages. The one who has drawn our attention more than perhaps any other living writer to those very marvels of coadaptation, is the foremost to maintain that they are the result not of desire and design, either within the creature or without it, but of blind chance, working no whither, and due but to the accumulation of innumerable lucky accidents. "There are men," writes Professor Tyndall in the 'Nineteenth Century,' for last November, "and by no means the minority, who, however wealthy in regard to facts, can never rise into the region of principles; and they are sometimes intolerant of those that can. They are formed to plod meritoriously on in the lower levels of thought; unpossessed of the pinions necessary to reach the heights, they cannot realize the mental act--the act of inspiration it might well be called--by which a man of genius, after long pondering and proving, reaches a theoretic conception which unravels and illuminates the tangle of centuries of observation and experiment. There are minds, it may be said in passing, who, at the present moment, stand in this relation to Mr. Darwin." The more rhapsodical parts of the above must go for what they are worth, but I should be sorry to think that what remains conveyed a censure which might fall justly on myself. As I read the earlier part of the passage I confess that I imagined the conclusion was going to be very different from what it proved to be. Fresh from the study of the older men and also of Mr. Darwin himself, I failed to see that Mr. Darwin had "unravelled and illuminated" a tangled skein, but believed him, on the contrary, to have tangled and obscured what his predecessors had made in great part, if not wholly, plain. With the older writers, I had felt as though in the hands of men who wished to understand themselves and to make their reader understand them with the smallest possible exertion. The older men, if not in full daylight, at any rate saw in what quarter of the sky the dawn was breaking, and were looking steadily towards it. It is not they who have put their hands over their own eyes and ours, and who are crying out that there is no light, but chance and blindness everywhere. FOOTNOTES: [23] Page 210, first edition. CHAPTER V. THE TELEOLOGICAL EVOLUTION OF ORGANISM--THE PHILOSOPHY OF THE UNCONSCIOUS. I have stated the foregoing in what I take to be an extreme logical development, in order that the reader may more easily perceive the consequences of those premises which I am endeavouring to re-establish. But it must not be supposed that an animal or plant has ever conceived the idea of some organ widely different from any it was yet possessed of, and has set itself to design it in detail and grow towards it. The small jelly-speck, which we call the amoeba, has no organs save what it can extemporize as occasion arises. If it wants to get at anything, it thrusts out part of its jelly, which thus serves it as an arm or hand: when the arm has served its purpose, it is absorbed into the rest of the jelly, and has now to do the duty of a stomach by helping to wrap up what it has just purveyed. The small round jelly-speck spreads itself out and envelops its food, so that the whole creature is now a stomach, and nothing but a stomach. Having digested its food, it again becomes a jelly-speck, and is again ready to turn part of itself into hand or foot as its next convenience may dictate. It is not to be believed that such a creature as this, which is probably just sensitive to light and nothing more, should be able to form a conception of an eye and set itself to work to grow one, any more than it is believable that he who first observed the magnifying power of a dew drop, or even he who first constructed a rude lens, should have had any idea in his mind of Lord Rosse's telescope with all its parts and appliances. Nothing could be well conceived more foreign to experience and common sense. Animals and plants have travelled to their present forms as man has travelled to any one of his own most complicated inventions. Slowly, step by step, through many blunders and mischances which have worked together for good to those that have persevered in elasticity. They have travelled as man has travelled, with but little perception of a want till there was also some perception of a power, and with but little perception of a power till there was a dim sense of want; want stimulating power, and power stimulating want; and both so based upon each other that no one can say which is the true foundation, but rather that they must be both baseless and, as it were, meteoric in mid air. They have seen very little ahead of a present power or need, and have been then most moral, when most inclined to pierce a little into futurity, but also when most obstinately declining to pierce too far, and busy mainly with the present. They have been so far blindfolded that they could see but for a few steps in front of them, yet so far free to see that those steps were taken with aim and definitely, and not in the dark. "Plus il a su," says Buffon, speaking of man, "plus il a pu, mais aussi moins il a fait, moins il a su." This holds good wherever life holds good. Wherever there is life there is a moral government of rewards and punishments understood by the amoeba neither better nor worse than by man. The history of organic development is the history of a moral struggle. We know nothing as yet about the origin of a creature able to feel want and power, nor yet what want and power spring from. It does not seem worth while to go into these questions until an understanding has been come to as to whether the interaction of want and power in some low form or forms of life which could assimilate matter, reproduce themselves, vary their actions, and be capable of remembering, will or will not suffice to explain the development of the varied organs and desires which we see in the higher vertebrates and man. When this question has been settled, then it will be time to push our inquiries farther back. But given such a low form of life as here postulated, and there is no force in Paley's pretended objection to the Darwinism of his time. "Give our philosopher," he says, "appetencies; give him a portion of living irritable matter (a nerve or the clipping of a nerve) to work upon; give also to his incipient or progressive forms the power of propagating their like in every stage of their alteration; and if he is to be believed, he could replenish the world with all the vegetable and animal productions which we now see in it."[24] After meeting this theory with answers which need not detain us, he continues:-- "The senses of animals appear to me quite incapable of receiving the explanation of their origin which this theory affords. Including under the word 'sense' the organ and the perception, we have no account of either. How will our philosopher get at vision or make an eye? Or, suppose the eye formed, would the perception follow? The same of the other senses. And this objection holds its force, ascribe what you will to the hand of time, to the power of habit, to changes too slow to be observed by man, or brought within any comparison which he is able to make of past things with the present. Concede what you please to these arbitrary and unattested superstitions, how will they help you? Here is no inception. No laws, no course, no powers of nature which prevail at present, nor any analogous to these would give commencement to a new sense; and it is in vain to inquire how that might proceed which would never _begin_." In answer to this, let us suppose that some inhabitants of another world were to see a modern philosopher so using a microscope that they should believe it to be a part of the philosopher's own person, which he could cut off from and join again to himself at pleasure, and suppose there were a controversy as to how this microscope had originated, and that one party maintained the man had made it little by little because he wanted it, while the other declared this to be absurd and impossible; I ask, would this latter party be justified in arguing that microscopes could never have been perfected by degrees through the preservation of and accumulation of small successive improvements, inasmuch as men could not have begun to want to use microscopes until they had had a microscope which should show them that such an instrument would be useful to them, and that hence there is nothing to account for the _beginning_ of microscopes, which might indeed make some progress when once originated, but which could never originate? It might be pointed out to such a reasoner, firstly, that as regards any acquired power the various stages in the acquisition of which he might be supposed able to remember, he would find that, logic notwithstanding, the wish did originate the power, and yet was originated by it, both coming up gradually out of something which was not recognisable as either power or wish, and advancing through vain beating of the air, to a vague effort, and from this to definite effort with failure, and from this to definite effort with success, and from this to success with little consciousness of effort, and from this to success with such complete absence of effort that he now acts unconsciously and without power of introspection, and that, do what he will, he can rarely or never draw a sharp dividing line whereat anything shall be said to begin, though none less certain that there has been a continuity in discontinuity, and a discontinuity in continuity between it and certain other past things; moreover, that his opponents postulated so much beginning of the microscope as that there should be a dew drop, even as our evolutionists start with a sense of touch, of which sense all the others are modifications, so that not one of them but is resolvable into touch by more or less easy stages; and secondly, that the question is one of fact and of the more evident deductions therefrom, and should not be carried back to those remote beginnings where the nature of the facts is so purely a matter of conjecture and inference. No plant or animal, then, according to our view, would be able to conceive more than a very slight improvement on its organization at a given time, so clearly as to make the efforts towards it that would result in growth of the required modification; nor would these efforts be made with any far-sighted perception of what next and next and after, but only of what next; while many of the happiest thoughts would come like all other happy thoughts--thoughtlessly; by a chain of reasoning too swift and subtle for conscious analysis by the individual, as will be more fully insisted on hereafter. Some of these modifications would be noticeable, but the majority would involve no more noticeable difference than can be detected between the length of the shortest day, and that of the shortest but one. Thus a bird whose toes were not webbed, but who had under force of circumstances little by little in the course of many generations learned to swim, either from having lived near a lake, and having learnt the art owing to its fishing habits, or from wading about in shallow pools by the sea-side at low water, and finding itself sometimes a little out of its depth and just managing to scramble over the intermediate yard or so between it and safety--such a bird did not probably conceive the idea of swimming on the water and set itself to learn to do so, and then conceive the idea of webbed feet and set itself to get webbed feet. The bird found itself in some small difficulty, out of which it either saw, or at any rate found that it could extricate itself by striking out vigorously with its feet and extending its toes as far as ever it could; it thus began to learn the art of swimming and conceived the idea of swimming synchronously, or nearly so; or perhaps wishing to get over a yard or two of deep water, and trying to do so without being at the trouble of rising to fly, it would splash and struggle its way over the water, and thus practically swim, though without much perception of what it had been doing. Finding that no harm had come to it, the bird would do the same again, and again; it would thus presently lose fear, and would be able to act more calmly; then it would begin to find out that it could swim a little, and if its food lay much in the water so that it would be of great advantage to it to be able to alight and rest without being forced to return to land, it would begin to make a practice of swimming. It would now discover that it could swim the more easily according as its feet presented a more extended surface to the water; it would therefore keep its toes extended whenever it swam, and as far as in it lay, would make the most of whatever skin was already at the base of its toes. After very many generations it would become web-footed, if doing as above described should have been found continuously convenient, so that the bird should have continuously used the skin about its toes as much as possible in this direction. For there is a margin in every organic structure (and perhaps more than we imagine in things inorganic also), which will admit of references, as it were, side notes, and glosses upon the original text. It is on this margin that we may err or wander--the greatness of a mistake depending rather upon the extent of the departure from the original text, than on the direction that the departure takes. A little error on the bad side is more pardonable, and less likely to hurt the organism than a too great departure upon the right one. This is a fundamental proposition in any true system of ethics, the question what is too much or too sudden being decided by much the same higgling as settles the price of butter in a country market, and being as invisible as the link which connects the last moment of desire with the first of power and performance, and with the material result achieved. It is on this margin that the fulcrum is to be found, whereby we obtain the little purchase over our structure, that enables us to achieve great results if we use it steadily, with judgment, and with neither too little effort nor too much. It is by employing this that those who have a fancy to move their ears or toes without moving other organs learn to do so. There is a man at the Agricultural Hall now playing the violin with his toes, and playing it, as I am told, sufficiently well. The eye of the sailor, the wrist of the conjuror, the toe of the professional medium, are all found capable of development to an astonishing degree, even in a single lifetime; but in every case success has been attained by the simple process of making the best of whatever power a man has had at any given time, and by being on the look out to take advantage of accident, and even of misfortune. If a man would learn to paint, he must not theorize concerning art, nor think much what he would do beforehand, but he must do _something_--it does not matter what, except that it should be whatever at the moment will come handiest and easiest to him; and he must do that something as well as he can. This will presently open the door for something else, and a way will show itself which no conceivable amount of searching would have discovered, but which yet could never have been discovered by sitting still and taking no pains at all. "Dans l'animal," says Buffon, "il y a moins de jugement que de sentiment."[25] It may appear as though this were blowing hot and cold with the same breath, inasmuch as I am insisting that important modifications of structure have been always purposive; and at the same time am denying that the creature modified has had any purpose in the greater part of all those actions which have at length modified both structure and instinct. Thus I say that a bird learns to swim without having any purpose of learning to swim before it set itself to make those movements which have resulted in its being able to do so. At the same time I maintain that it has only learned to swim by trying to swim, and this involves the very purpose which I have just denied. The reconciliation of these two apparently irreconcilable contentions must be found in the consideration that the bird was not the less trying to swim, merely because it did not know the name we have chosen to give to the art which it was trying to master, nor yet how great were the resources of that art. A person, who knew all about swimming, if from some bank he could watch our supposed bird's first attempt to scramble over a short space of deep water, would at once declare that the bird was trying to swim--if not actually swimming. Provided then that there is a very little perception of, and prescience concerning, the means whereby the next desired end may be attained, it matters not how little in advance that end may be of present desires or faculties; it is still reached through purpose, and must be called purposive. Again, no matter how many of these small steps be taken, nor how absolute was the want of purpose or prescience concerning any but the one being actually taken at any given moment, this does not bar the result from having been arrived at through design and purpose. If each one of the small steps is purposive the result is purposive, though there was never purpose extended over more than one, two, or perhaps at most three, steps at a time. Returning to the art of painting for an example, are we to say that the proficiency which such a student as was supposed above will certainly attain, is not due to design, merely because it was not until he had already become three parts excellent that he knew the full purport of all that he had been doing? When he began he had but vague notions of what he would do. He had a wish to learn to represent nature, but the line into which he has settled down has probably proved very different from that which he proposed to himself originally. Because he has taken advantage of his accidents, is it, therefore, one whit the less true that his success is the result of his desires and his design? The 'Times' pointed out not long ago that the theory which now associates meteors and comets in the most unmistakable manner, was suggested by one accident, and confirmed by another. But the writer added well that "such accidents happen only to the zealous student of nature's secrets." In the same way the bird that is taking to the habit of swimming, and of making the most of whatever skin it already has between its toes, will have doubtless to thank accidents for no small part of its progress; but they will be such accidents as could never have happened to, or been taken advantage of by any creature which was not zealously trying to make the most of itself--and between such accidents as this, and design, the line is hard to draw; for if we go deep enough we shall find that most of our design resolves itself into as it were a shaking of the bag to see what will come out that will suit our purpose, and yet at the same time that most of our shaking of the bag resolves itself into a design that the bag shall contain only such and such things, or thereabouts. Again, the fact that animals are no longer conscious of design and purpose in much that they do, but act unreflectingly, and as we sometimes say concerning ourselves "automatically" or "mechanically"--that they have no idea whatever of the steps whereby they have travelled to their present state, and show no sign of doubt about what must have been at one time the subject of all manner of doubts, difficulties, and discussions--that whatever sign of reflection they now exhibit is to be found only in case of some novel feature or difficulty presenting itself; these facts do not bar that the results achieved should be attributed to an inception in reason, design, and purpose, no matter how rapidly and as we call it instinctively, the creatures may now act. For if we look closely at such an invention as the steam engine in its latest and most complicated developments, about which there can be no dispute but that they are achievements of reason, purpose, and design, we shall find them present us with examples of all those features the presence of which in the handiwork of animals is too often held to bar reason and purpose from having had any share therein. Assuredly such men as the Marquis of Worcester and Captain Savery had very imperfect ideas as to the upshot of their own action. The simplest steam engine now in use in England is probably a marvel of ingenuity as compared with the highest development which appeared possible to these two great men, while our newest and most highly complicated engines would seem to them more like living beings than machines. Many, again, of the steps leading to the present development have been due to action which had but little heed of the steam engine, being the inventions of attendants whose desire was to save themselves the trouble of turning this or that cock, and who were indifferent to any other end than their own immediate convenience. No step in fact along the whole route was ever taken with much perception of what would be the next step after the one being taken at any given moment. Nor do we find that an engine made after any old and well-known pattern is now made with much more consciousness of design than we can suppose a bird's nest to be built with. The greater number of the parts of any such engine, are made by the gross as it were like screws and nuts, which are turned out by machinery and in respect of which the labour of design is now no more felt than is the design of him who first invented the wheel. It is only when circumstances require any modification in the article to be manufactured that thought and design will come into play again; but I take it few will deny that if circumstances compel a bird either to give up a nest three-parts built altogether, or to make some trifling deviation from its ordinary practice, it will in nine cases out of ten make such deviation as shall show that it had thought the matter over, and had on the whole concluded to take such and such a course, that is to say, that it had reasoned and had acted with such purpose as its reason had dictated. And I imagine that this is the utmost that anyone can claim even for man's own boasted powers. Set the man who has been accustomed to make engines of one type, to make engines of another type without any intermediate course of training or instruction, and he will make no better figure with his engines than a thrush would do if commanded by her mate to make a nest like a blackbird. It is vain then to contend that the ease and certainty with which an action is performed, even though it may have now become matter of such fixed habit that it cannot be suddenly and seriously modified without rendering the whole performance abortive, is any argument against that action having been an achievement of design and reason in respect of each one of the steps that have led to it; and if in respect of each one of the steps then as regards the entire action; for we see our own most reasoned actions become no less easy, unerring, automatic, and unconscious, than the actions which we call instinctive when they have been repeated a sufficient number of times. This has been often pointed out, but I insisted upon it and developed it in 'Life and Habit,' more I believe than has been done hitherto, at the same time making it the key to many phenomena of growth and heredity which without such key seem explained by words rather than by any corresponding peace of mind in our ideas concerning them. Seeing that I dwelt much on the importance of bearing in mind the vanishing tendency of consciousness, volition, and memory upon their becoming intense, a tendency which no one after five minutes' reflection will venture to deny, some reviewers have imagined that I am advocating the same views as have been put forward by Von Hartmann under the title of 'the Philosophy of the Unconscious.' Unless, however, I am much mistaken, their opinion is without foundation. For so far as I can gather, Von Hartmann personifies the unconscious and makes it act and think--in fact deifies it--whereas I only infer a certain history for certain of our growths and actions in consequence of observing that often repeated actions come in time to be performed unconsciously. I cannot think I have done more than note a fact which all must acknowledge, and drawn from it an inference which may or may not be true, but which is at any rate perfectly intelligible, whereas if Von Hartmann's meaning is anything like what Mr. Sully says it is,[26] I can only say that it has not been given to me to form any definite conception whatever as to what that meaning may be. I am encouraged moreover to hope that I am not in the same condemnation with Von Hartmann--if, indeed, Von Hartmann is to be condemned, about which I know nothing--by the following extract from a German Review of 'Life and Habit.' "Der erste dieser beiden Erklärungsversuche, ist eine wahre 'Philosophie des Unbewussten' nicht des Hartmann'schen Unbewussten welches hellsehend und wunderthätig von aussen in die natürliche Entwickelung der Organismen eingreift, sondern eines Unbewussten welches wie der Verfasser zeigt, in allen organischen Wesen anzunehmen unsere eigene Erfahrung und die Stufenfolge der Organismen von den Moneren und Amoeben bis zu den höchsten Pflanzen und Thieren und uns selbst aufwärts--uns gestattet, wenn nicht uns nöthigt. Der Gedankengang dieser neuen oder wenigstens in diesem Sinne wohl zum ersten Male consequent im Einzelnen durchgeführten Philosophie des Unbewussten ist, seinen Hauptzügen nach kurz angedeutet, folgender."[27] Even here I am made to personify more than I like; I do not wish to say that the unconscious does this or that, but that when we have done this or that sufficiently often we do it unconsciously. If the foregoing be granted, and it be admitted that the unconsciousness and seeming automatism with which any action may be performed is no bar to its having a foundation in memory, reason, and at one time consciously recognized effort--and this I believe to be the chief addition which I have ventured to make to the theory of Buffon and Dr. Erasmus Darwin--then the wideness of the difference between the Darwinism of eighty years ago and the Darwinism of to-day becomes immediately apparent, and it also becomes apparent, how important and interesting is the issue which is raised between them. According to the older Darwinism the lungs are just as purposive as the corkscrew. They, no less than the corkscrew, are a piece of mechanism designed and gradually improved upon and perfected by an intelligent creature for the gratification of its own needs. True there are many important differences between mechanism which is part of the body, and mechanism which is no such part, but the differences are such as do not affect the fact that in each case the result, whether, for example, lungs or corkscrew, is due to desire, invention, and design. And now I will ask one more question, which may seem, perhaps, to have but little importance, but which I find personally interesting. I have been told by a reviewer, of whom upon the whole I have little reason to complain, that the theory I put forward in 'Life and Habit,' and which I am now again insisting on, is pessimism--pure and simple. I have a very vague idea what pessimism means, but I should be sorry to believe that I am a pessimist. Which, I would ask, is the pessimist? He who sees love of beauty, design, steadfastness of purpose, intelligence, courage, and every quality to which success has assigned the name of "worth," as having drawn the pattern of every leaf and organ now and in all past time, or he who sees nothing in the world of nature but a chapter of accidents and of forces interacting blindly? FOOTNOTES: [24] 'Nat. Theol.,' ch. xxiii. [25] 'Oiseaux,' vol. i. p. 5. [26] 'Westminster Review,' vol. xlix. p. 124. [27] Translation: "The first of these two attempts is a true 'philosophy of the unconscious,' not Hartmann's unconscious, which influences the natural evolution of organism from without as though by Providence and miracle, but of an unconscious, which, as the author shows, our own experience and the progressive succession of organisms from the monads and amoebæ up to the highest plants and animals, including ourselves, allows, if it does not compel us to assume [as obtaining] in all organic beings. This philosophy of the unconscious is new, or at any rate now for the first time carried out consequentially in detail; its main features, briefly stated are as follows." CHAPTER VI. SCHEME OF THE REMAINDER OF THE WORK. HISTORICAL SKETCH OF THE THEORY OF EVOLUTION. I have long felt that evolution must stand or fall according as it is made to rest or not on principles which shall give a definite purpose and direction to the variations whose accumulation results in specific, and ultimately in generic differences. In other words, according as it is made to stand upon the ground first clearly marked out for it by Dr. Erasmus Darwin and afterwards adopted by Lamarck, or on that taken by Mr. Charles Darwin. There is some reason to fear that in consequence of the disfavour into which modern Darwinism is seen to be falling by those who are more closely watching the course of opinion upon this subject, evolution itself may be for a time discredited as something inseparable from the theory that it has come about mainly through "the means" of natural selection. If people are shown that the arguments by which a somewhat startling conclusion has been reached will not legitimately lead to that conclusion, they are very ready to assume that the conclusion must be altogether unfounded, especially when, as in the present case, there is a vast mass of vested interests opposed to the conclusion. Few know that there are other great works upon descent with modification besides Mr. Darwin's. Not one person in ten thousand has any distinct idea of what Buffon, Dr. Darwin, and Lamarck propounded. Their names have been discredited by the very authors who have been most indebted to them; there is hardly a writer on evolution who does not think it incumbent upon him to warn Lamarck off the ground which he at any rate made his own, and to cast a stone at what he will call the "shallow speculations" or "crude theories" or the "well-known doctrine" of the foremost exponent of Buffon and Dr. Darwin. Buffon is a great name, Dr. Darwin is no longer even this, and Lamarck has been so systematically laughed at that it amounts to little less than philosophical suicide for anyone to stand up in his behalf. Not one of our scientific elders or chief priests but would caution a student rather to avoid the three great men whom I have named than to consult them. It is a perilous task therefore to try and take evolution from the pedestal on which it now appears to stand so securely, and to put it back upon the one raised for it by its propounders; yet this is what I believe will have to be done sooner or later unless the now general acceptance of evolution is to be shaken more rudely than some of its upholders may anticipate. I propose therefore to give a short biographical sketch of the three writers whose works form new departures in the history of evolution, with a somewhat full _résumé_ of the positions they took in regard to it. I will also touch briefly upon some other writers who have handled the same subject. The reader will thus be enabled to follow the development of a great conception as it has grown up in the minds of successive men of genius, and by thus growing with it, as it were, through its embryonic stages, he will make himself more thoroughly master of it in all its bearings. I will then contrast the older with the newer Darwinism, and will show why the 'Origin of Species,' though an episode of incalculable value, cannot, any more than the 'Vestiges of Creation,' take permanent rank in the literature of evolution. It will appear that the evolution of evolution has gone through the following principal stages:-- I. A general conception of the fact that specific types were not always immutable. This was common to many writers, both ancient and modern; it has been occasionally asserted from the times of Anaximander and Lucretius to those of Bacon and Sir Walter Raleigh. II. A definite conception that animal and vegetable forms were so extensively mutable that few (and, if so, perhaps but one) could claim to be of an original stock; the direct effect of changed conditions being assigned as the cause of modification, and the important consequences of the struggle for existence being in many respects fully recognized. The fact of design or purpose in connection with organism, as causing habits and thus as underlying all variation, was also indicated with some clearness, but was not thoroughly understood. This phase must be identified with the name of Buffon, who, as I will show reason for believing, would have carried his theory much further if he had not felt that he had gone as far in the right direction as was then desirable. Buffon put forward his opinions, with great reserve and yet with hardly less frankness, in volume after volume from 1749 to 1788, the year of his death, but they do not appear to have taken root at once in France. They took root in England, and were thence transplanted back to France. III. A development in England of the Buffonian system, marked by glimpses of the unity between offspring and parents, and broad suggestions to the effect that the former must be considered as capable of remembering, under certain circumstances, what had happened to it, and what it did, when it was part of the personality of those from whom it had descended. A definite belief, openly expressed, that not only are many species mutable, but that all living forms, whether animal or vegetable, are descended from a single, or at any rate from not many, original low forms of life, and this as the direct consequence of the actions and requirements of the living forms themselves, and as the indirect consequence of changed conditions. A definite cause is thus supposed to underlie variations, and the resulting adaptations become purposive; but this was not said, nor, I am afraid, seen. This is the original Darwinism of Dr. Erasmus Darwin. It was put forward in his 'Zoonomia,' in 1794, and was adopted almost in its entirety by Lamarck, who, when he had caught the leading idea (probably through a French translation of the 'Loves of the Plants,' which appeared in 1800), began to expound it in 1801; in 1802, 1803, 1806, and 1809, he developed it with greater fulness of detail than Dr. Darwin had done, but perhaps with a somewhat less nice sense of some important points. Till his death, in 1831, Lamarck, as far as age and blindness would permit, continued to devote himself to the exposition of the theory of descent with modification. IV. A more distinct perception of the unity of parents and offspring, with a bolder reference of the facts of heredity (whether of structure or instinct), to memory pure and simple; a clearer perception of the consequences that follow from the survival of the fittest, and a just view of the relation in which those consequences stand to "the circumstance-suiting" power of animals and plants; a reference of the variations whose accumulation results in species, to the volition of the animal or plant which varies, and perhaps a dawning perception that all adaptations of structure to need must therefore be considered as "purposive." This must be connected with Mr. Matthew's work on 'Naval Timber and Arboriculture,' which appeared in 1831. The remarks which it contains in reference to evolution are confined to an appendix, but when brought together, as by Mr. Matthew himself, in the 'Gardeners' Chronicle' for April 7, 1860, they form one of the most perfect yet succinct expositions of the theory of evolution that I have ever seen. I shall therefore give them in full.[28] This book was well received, and was reviewed in the 'Quarterly Review,'[29] but seems to have been valued rather for its views on naval timber than on evolution. Mr. Matthew's merit lies in a just appreciation of the importance of each one of the principal ideas which must be present in combination before we can have a correct conception of evolution, and of their bearings upon one another. In his scheme of evolution I find each part kept in due subordination to the others, so that the whole theory becomes more coherent and better articulated than I have elsewhere found it; but I do not detect any important addition to the ideas which Dr. Darwin and Lamarck had insisted upon. I pass over the 'Vestiges of Creation,' which should be mentioned only as having, as Mr. Charles Darwin truly says, "done excellent service in this country, in calling attention to this subject, in removing prejudice, and in thus preparing the ground for the reception of analogous views."[30] The work neither made any addition to ideas which had been long familiar, nor arranged old ones in a satisfactory manner. Such as it is, it is Dr. Darwin and Lamarck, but Dr. Darwin and Lamarck spoiled. The first edition appeared in 1844. I also pass over Isidore Geoffroy St. Hilaire's 'Natural History,' which appeared 1854-62, and the position of which is best described by calling it intermediate between the one which Buffon thought fit to pretend to take, and that actually taken by Lamarck. The same may be said also of Étienne Geoffroy. I will, however, just touch upon these writers later on. A short notice, again, will suffice for the opinions of Goethe, Treviranus, and Oken, none of whom can I discover as having originated any important new idea; but knowing no German, I have taken this opinion from the résumé of each of these writers, given by Professor Haeckel in his 'History of Creation.' V. A time of retrogression, during which we find but little apparent appreciation of the unity between parents and offspring; no reference to memory in connection with heredity, whether of instinct or structure; an exaggerated view of the consequences which may be deduced from the fact that the fittest commonly survive in the struggle for existence; the denial of any known principle as underlying variations; comparatively little appreciation of the circumstance-suiting power of plants and animals, and a rejection of purposiveness. By far the most important exponent of this phase of opinion concerning evolution is Mr. Charles Darwin, to whom, however, we are more deeply indebted than to any other living writer for the general acceptance of evolution in one shape or another. The 'Origin of Species' appeared in 1859, the same year, that is to say, as the second volume of Isidore Geoffroy's 'Histoire Naturelle Générale.' VI. A reaction against modern Darwinism, with a demand for definite purpose and design as underlying variations. The best known writers who have taken this line are the Rev. J. J. Murphy and Professor Mivart, whose 'Habit and intelligence' and 'Genesis of Species' appeared in 1869 and 1871 respectively. In Germany Professor Hering has revived the idea of memory as explaining the phenomena of heredity satisfactorily, without probably having been more aware that it had been advanced already than I was myself when I put it forward recently in 'Life and Habit.' I have never seen the lecture in which Professor Hering has referred the phenomena of heredity to memory, but will give an extract from it which appeared in the 'Athenæum,' as translated by Professor Ray Lankester.[31] The only new feature which I believe I may claim to have added to received ideas concerning evolution, is a perception of the fact that the unconsciousness with which we go through our embryonic and infantile stages, and with which we discharge the greater number and more important of our natural functions, is of a piece with what we observe concerning all habitual actions, as well as concerning memory; an explanation of the phenomena of old age; and of the main principle which underlies longevity. I may, perhaps, claim also to have more fully explained the passage of reason into instinct than I yet know of its having been explained elsewhere.[32] FOOTNOTES: [28] See ch. xviii. of this volume. [29] Vol. xlix. p. 125. [30] 'Origin of Species,' Hist. Sketch, xvii. [31] See page 199 of this volume. [32] Apropos of this, a friend has kindly sent me the following extract from Balzac:--"Historiquement, les paysans sont encore au lendemain de la Jacquerie, leur défaite est restée inscrite dans leur cervelle. _Ils ne se souviennent plus du fait, il est passé à l'état d'idée instinctive._"--Balzac, 'Les Paysans,' v. CHAPTER VII. PRE-BUFFONIAN EVOLUTION, AND SOME GERMAN WRITERS. Let us now proceed to the fuller development of the foregoing sketch. "Undoubtedly," says Isidore Geoffroy, "from the most ancient times many philosophers have imagined vaguely that one species can be transformed into another. This doctrine seems to have been adopted by the Ionian school from the sixth century before our era.... Undoubtedly also the same opinion reappeared on several occasions in the middle ages, and in modern times; it is to be found in some of the hermetic books, where the transmutation of animal and vegetable species, and that of metals, are treated as complementary to one another. In modern times we again find it alluded to by some philosophers, and especially by Bacon, whose boldness is on this point extreme. Admitting it as 'incontestable that plants sometimes degenerate so far as to become plants of another species,' Bacon did not hesitate to try and put his theory into practice. He tried, in 1635, to give 'the rules' for the art of changing 'plants of one species into those of another.'" This must be an error. Bacon died in 1626. The passage of Bacon referred to is in 'Nat. Hist.,' Cent. vi. ("Experiments in consort touching the degenerating of plants, and the transmutation of them one into another"), and is as follows:-- "518. This rule is certain, that plants for want of culture degenerate to be baser in the same kind; and sometimes so far as to change into another kind. 1. The standing long and not being removed maketh them degenerate. 2. Drought unless the earth, of itself, be moist doth the like. 3. So doth removing into worse earth, or forbearing to compost the earth; as we see that water mint turneth into field mint, and the colewort into rape by neglect, &c." "525. It is certain that in very steril years corn sown will grow to another kind:-- 'Grandia sæpe quibus mandavimus hordea sulcis, Infelix lolium, et steriles dominantur avenæ.' And generally it is a rule that plants that are brought forth for culture, as corn, will sooner change into other species, than those that come of themselves; for that culture giveth but an adventitious nature, which is more easily put off." Changed conditions, according to Bacon (though he does not use these words), appear to be "the first rule for the transmutation of plants." "But how much value," continues M. Geoffroy, "ought to be attached to such prophetic glimpses, when they were neither led up to, nor justified by any serious study? They are conjectures only, which, while bearing evidence to the boldness or rashness of those who hazarded them, remain almost without effect upon the advance of science. Bacon excepted, they hardly deserve to be remembered. As for De Maillet, who makes birds spring from flying fishes, reptiles from creeping fishes, and men from tritons, his dreams, taken in part from Anaximander, should have their place not in the history of science, but in that of the aberrations of the human mind."[33] A far more forcible and pregnant passage, however, is the following, from Sir Walter Raleigh's 'History of the World,' which Mr. Garnett has been good enough to point out to me:-- "For mine owne opinion I find no difference but only in magnitude between the Cat of Europe, and the Ounce of India; and even those dogges which are become wild in Hispagniola, with which the Spaniards used to devour the naked Indians, are now changed to Wolves, and begin to destroy the breed of their Cattell, and doe often times teare asunder their owne children. The common crow and rooke of India is full of red feathers in the droun'd and low islands of Caribana, and the blackbird and thrush hath his feathers mixt with black and carnation in the north parts of Virginia. The Dog-fish of England is the Sharke of the South Ocean. For if colour or magnitude made a difference of Species, then were the Negroes, which wee call the Blacke-Mores, _non animalia rationalia_, not Men but some kind of strange Beasts, and so the giants of the South America should be of another kind than the people of this part of the World. We also see it dayly that the nature of fruits are changed by transplantation."[34] For information concerning the earliest German writers on evolution, I turn to Professor Haeckel's 'History of Creation,' and find Goethe's name to head the list. I do not gather, however, that Goethe added much to the ideas which Buffon had already made sufficiently familiar. Professor Haeckel does not seem to be aware of Buffon's work, and quotes Goethe as making an original discovery when he writes, in the year 1796:--"Thus much then we have gained, that we may assert without hesitation that all the more perfect organic natures, such as fishes, amphibious animals, birds, mammals, and man at the head of the last, were all formed upon one original type, which only varies more or less in parts which were none the less permanent, and still daily changes and modifies its form by propagation."[35] But these, as we shall see, are almost Buffon's own words--words too that Buffon insisted on for many years. Again Professor Haeckel quotes Goethe as writing in the year 1807:-- "If we consider plants and animals in their most imperfect condition, they can hardly be distinguished." This, however, had long been insisted upon by Bonnet and Dr. Erasmus Darwin, the first of whom was a naturalist of world-wide fame, while the 'Zoonomia' of Dr. Darwin had been translated into German between the years 1795 and 1797, and could hardly have been unknown to Goethe in 1807, who continues: "But this much we may say, that the creatures which by degrees emerge as plants and animals out of a common phase where they are barely distinguishable, arrive at perfection in two opposite directions, so that the plant in the end reaches its highest glory in the tree, which is immovable and stiff, the animal in man who possesses the greatest elasticity and freedom." Professor Haeckel considers this to be a remarkable passage, but I do not think it should cause its author to rank among the founders of the evolution theory, though he may justly claim to have been one of the first to adopt it. Goethe's anatomical researches appear to have been more important, but I cannot find that he insisted on any new principle, or grasped any unfamiliar conception, which had not been long since grasped and widely promulgated by Buffon and by Dr. Erasmus Darwin. Treviranus (1776-1837), whom Professor Haeckel places second to Goethe, is clearly a disciple of Buffon, and uses the word "degeneration" in the same sense as Buffon used it many years earlier, that is to say, as "descent with modification," without any reference to whether the offspring was, as Buffon says, "perfectionné ou dégradé." He cannot claim, any more than Goethe, to rank as a principal figure in the history of evolution. Of Oken, Professor Haeckel says that his 'Naturphilosophie,' which appeared in 1809--in the same year, that is to say, as the 'Philosophie Zoologique' of Lamarck--was "the nearest approach to the natural theory of descent, newly established by Mr. Charles Darwin," of any work that appeared in the first decade of our century. But I do not detect any important difference of principle between his system and that of Dr. Erasmus Darwin, among whose disciples he should be reckoned. "We now turn," says Professor Haeckel after referring to a few more German writers who adopted a belief in evolution, "from the German to the French nature-philosophers who have likewise held the theory of descent, since the beginning of this century. At their head stands Jean Lamarck, who occupies the first place next to Darwin and Goethe in the history of the doctrine of Filiation."[36] This is rather a surprising assertion, but I will leave the reader of the present volume to assign the value which should be attached to it. Professor Haeckel devotes ten lines to Dr. Erasmus Darwin, who he declares "expresses views very similar to those of Goethe and Lamarck, without, however, _then_ knowing anything about these two men;" which is all the more strange inasmuch as Dr. Darwin preceded them, and was a good deal better known to them, probably, than they to him; but it is plain Professor Haeckel has no acquaintance with the 'Zoonomia' of Dr. Erasmus Darwin. From all, then, that I am able to collect, I conclude that I shall best convey to the reader an idea of the different phases which the theory of descent with modification has gone through, by confining his attention almost entirely to Buffon, Dr. Erasmus Darwin, Lamarck, and Mr. Charles Darwin. FOOTNOTES: [33] 'Hist. Nat. Gen.,' vol. ii. p. 385, 1859. [34] 'History of the World,' bk. i. ch. vii. § 9 ('Athenæum,' March 27, 1875). [35] 'History of Creation,' vol. i. p. 91. [36] 'History of Creation,' bk. i. ch. iii. (H. S. King, 1876). CHAPTER VIII. BUFFON--MEMOIR. Buffon, says M. Flourens, was born at Montbar, on the 7th of September, 1707; he died in Paris, at the Jardin du Roi, on the 16th of April, 1788, aged 81 years. More than fifty of these years, as he used himself to say, he had passed at his writing-desk. His father was a councillor of the parliament of Burgundy. His mother was celebrated for her wit, and Buffon cherished her memory. He studied at Dijon with much _éclat_, and shortly after leaving became accidentally acquainted with the Duke of Kingston, a young Englishman of his own age, who was travelling abroad with a tutor. The three travelled together in France and Italy, and Buffon then passed some months in England. Returning to France, he translated Hales's 'Vegetable Statics' and Newton's 'Treatise on Fluxions.' He refers to several English writers on natural history in the course of his work, but I see he repeatedly spells the English name Willoughby, "Willulghby." He was appointed superintendent of the Jardin du Roi in 1739, and from thenceforth devoted himself to science. In 1752 Buffon married Mdlle. de Saint Bélin, whose beauty and charm of manner were extolled by all her contemporaries. One son was born to him, who entered the army, became a colonel, and I grieve to say, was guillotined at the age of twenty-nine, a few days only before the extinction of the Reign of Terror. Of this youth, who inherited the personal comeliness and ability of his father, little is recorded except the following story. Having fallen into the water and been nearly drowned when he was about twelve years old, he was afterwards accused of having been afraid: "I was so little afraid," he answered, "that though I had been offered the hundred years which my grandfather lived, I would have died then and there, if I could have added one year to the life of my father;" then thinking for a minute, a flush suffused his face, and he added, "but I should petition for one quarter of an hour in which to exult over the thought of what I was about to do." On the scaffold he showed much composure, smiling half proudly, half reproachfully, yet wholly kindly upon the crowd in front of him. "Citoyens," he said, "Je me nomme Buffon," and laid his head upon the block. The noblest outcome of the old and decaying order, overwhelmed in the most hateful birth frenzy of the new. So in those cataclysms and revolutions which take place in our own bodies during their development, when we seem studying in order to become fishes and suddenly make, as it were, different arrangements and resolve on becoming men--so, doubtless, many good cells must go, and their united death cry comes up, it may be, in the pain which an infant feels on teething. But to return. The man who could be father of such a son, and who could retain that son's affection, as it is well known that Buffon retained it, may not perhaps always be strictly accurate, but it will be as well to pay attention to whatever he may think fit to tell us. These are the only people whom it is worth while to look to and study from. "Glory," said Buffon, after speaking of the hours during which he had laboured, "glory comes always after labour if she can--_and she generally can_." But in his case she could not well help herself. "He was conspicuous," says M. Flourens, "for elevation and force of character, for a love of greatness and true magnificence in all he did. His great wealth, his handsome person, and graceful manners seemed in correspondence with the splendour of his genius, so that of all the gifts which Fortune has it in her power to bestow she had denied him nothing." Many of his epigrammatic sayings have passed into proverbs: for example, that "genius is but a supreme capacity for taking pains." Another and still more celebrated passage shall be given in its entirety and with its original setting. "Style," says Buffon, "is the only passport to posterity. It is not range of information, nor mastery of some little known branch of science, nor yet novelty of matter that will ensure immortality. Works that can claim all this will yet die if they are conversant about trivial objects only, or written without taste, genius and true nobility of mind; for range of information, knowledge of details, novelty of discovery are of a volatile essence and fly off readily into other hands that know better how to treat them. The matter is foreign to the man, and is not of him; the manner is the man himself."[37] "Le style, c'est l'homme même." Elsewhere he tells us what true style is, but I quote from memory and cannot be sure of the passage. "Le style," he says, "est comme le bonheur; il vient de la douceur de l'âme." Is it possible not to think of the following?-- "But whether there be prophecies they shall fail; whether there be tongues they shall cease; whether there be knowledge it shall vanish away ... and now abideth faith, hope and charity, these three; but the greatest of these is charity."[38] FOOTNOTES: [37] 'Discours de Réception à l'Académie Française.' [38] 1 Cor. xiii. 8, 13. CHAPTER IX. BUFFON'S METHOD--THE IRONICAL CHARACTER OF HIS WORK. Buffon's idea of a method amounts almost to the denial of the possibility of method at all. "The true method," he writes, "is the complete description and exact history of each particular object,"[39] and later on he asks, "is it not more simple, more natural and more true to call an ass an ass, and a cat a cat, than to say, without knowing why, that an ass is a horse, and a cat a lynx."[40] He admits such divisions as between animals and vegetables, or between vegetables and minerals, but that done, he rejects all others that can be founded on the nature of things themselves. He concludes that one who could see things in their entirety and without preconceived opinions, would classify animals according to the relations in which he found himself standing towards them:-- "Those which he finds most necessary and useful to him will occupy the first rank; thus he will give the precedence among the lower animals to the dog and the horse; he will next concern himself with those which without being domesticated, nevertheless occupy the same country and climate as himself, as for example stags, hares, and all wild animals; nor will it be till after he has familiarized himself with all these that curiosity will lead him to inquire what inhabitants there may be in foreign climates, such as elephants, dromedaries, &c. The same will hold good for fishes, birds, insects, shells, and for all nature's other productions; he will study them in proportion to the profit which he can draw from them; he will consider them in that order in which they enter into his daily life; he will arrange them in his head according to this order, which is in fact that in which he has become acquainted with them, and in which it concerns him to think about them. This order--the most natural of all--is the one which I have thought it well to follow in this volume. My classification has no more mystery in it than the reader has just seen ... it is preferable to the most profound and ingenious that can be conceived, for there is none of all the classifications which ever have been made or ever can be, which has not more of an arbitrary character than this has. Take it for all in all," he concludes, "it is more easy, more agreeable, and more useful, to consider things in their relation to ourselves than from any other standpoint."[41] "Has it not a better effect not only in a treatise on natural history, but in a picture or any work of art to arrange objects in the order and place in which they are commonly found, than to force them into association in virtue of some theory of our own? Is it not better to let the dog which has toes, come after the horse which has a single hoof, in the same way as we see him follow the horse in daily life, than to follow up the horse by the zebra, an animal which is little known to us, and which has no other connection with the horse than the fact that it has a single hoof?"[42] Can we suppose that Buffon really saw no more connection than this? The writer whom we shall presently find[43] declining to admit any essential difference between the skeletons of man and of the horse, can here see no resemblance between the zebra and the horse, except that they each have a single hoof. Is he to be taken at his word? It is perhaps necessary to tell the reader that Buffon carried the foregoing scheme into practice as nearly as he could in the first fifteen volumes of his 'Natural History.' He begins with man--and then goes on to the horse, the ass, the cow, sheep, goat, pig, dog, &c. One would be glad to know whether he found it always more easy to decide in what order of familiarity this or that animal would stand to the majority of his readers than other classifiers have found it to know whether an individual more resembles one species or another; probably he never gave the matter a thought after he had gone through the first dozen most familiar animals, but settled generally down into a classification which becomes more and more specific--as when he treats of the apes and monkeys--till he reaches the birds, when he openly abandons his original idea, in deference, as he says, to the opinion of "le peuple des naturalistes." Perhaps the key to this piece of apparent extravagance is to be found in the word "mystérieuse."[44] Buffon wished to raise a standing protest against mystery mongering. Or perhaps more probably, he wished at once "to turn to animals and plants under domestication," so as to insist early on the main object of his work--the plasticity of animal forms. I am inclined to think that a vein of irony pervades the whole, or much the greater part of Buffon's work, and that he intended to convey, one meaning to one set of readers, and another to another; indeed, it is often impossible to believe that he is not writing between his lines for the discerning, what the undiscerning were not intended to see. It must be remembered that his 'Natural History' has two sides,--a scientific and a popular one. May we not imagine that Buffon would be unwilling to debar himself from speaking to those who could understand him, and yet would wish like Handel and Shakespeare to address the many, as well as the few? But the only manner in which these seemingly irreconcilable ends could be attained, would be by the use of language which should be self-adjusting to the capacity of the reader. So keen an observer can hardly have been blind to the signs of the times which were already close at hand. Free-thinker though he was, he was also a powerful member of the aristocracy, and little likely to demean himself--for so he would doubtless hold it--by playing the part of Voltaire or Rousseau. He would help those who could see to see still further, but he would not dazzle eyes that were yet imperfect with a light brighter than they could stand. He would therefore impose upon people, as much as he thought was for their good; but, on the other hand, he would not allow inferior men to mystify them. "In the private character of Buffon," says Sir William Jardine in a characteristic passage, "we regret there is not much to praise; his disposition was kind and benevolent, and he was generally beloved by his inferiors, followers, and dependents, which were numerous over his extensive property; he was strictly honourable, and was an affectionate parent. In early youth he had entered into the pleasures and dissipations of life, and licentious habits seem to have been retained to the end. But the great blemish in such a mind was his declared infidelity; it presents one of those exceptions among the persons who have been devoted to the study of nature; and it is not easy to imagine a mind apparently with such powers, scarcely acknowledging a Creator, and when noticed, only by an arraignment for what appeared wanting or defective in his great works. So openly, indeed, was the freedom of his religious opinions expressed, that the indignation of the Sorbonne was provoked. He had to enter into an explanation which he in some way rendered satisfactory; and while he afterwards attended to the outward ordinances of religion, he considered them as a system of faith for the multitude, and regarded those most impolitic who most opposed them."[45] This is partly correct and partly not. Buffon was a free-thinker, and as I have sufficiently explained, a decided opponent of the doctrine that rudimentary and therefore useless organs were designed by a Creator in order to serve some useful end throughout all time to the creature in which they are found. He was not, surely, to hide the magnificent conceptions which he had been the first to grasp, from those who were worthy to receive them; on the other hand he would not tell the uninstructed what they would interpret as a license to do whatever they pleased, inasmuch as there was no God. What he did was to point so irresistibly in the right direction, that a reader of any intelligence should be in no doubt as to the road he ought to take, and then to contradict himself so flatly as to reassure those who would be shocked by a truth for which they were not yet ready. If I am right in the view which I have taken of Buffon's work, it is not easy to see how he could have formed a finer scheme, nor have carried it out more finely. I should, however, warn the reader to be on his guard against accepting my view too hastily. So far as I know I stand alone in taking it. Neither Dr. Darwin nor Flourens, nor Isidore Geoffroy, nor Mr. Charles Darwin see any subrisive humour in Buffon's pages; but it must be remembered that Flourens was a strong opponent of mutability, and probably paid but little heed to what Buffon said on this question; Isidore Geoffroy is not a safe guide, as will appear presently; Mr. Charles Darwin seems to have adopted the one half of Isidore Geoffroy's conclusions without verifying either; and Dr. Erasmus Darwin, who has no small share of a very pleasant conscious humour, yet sometimes rises to such heights of unconscious humour, that Buffon's puny labour may well have been invisible to him. Dr. Darwin wrote a great deal of poetry, some of which was about the common pump. Miss Seward tells us, as we shall see later on, that he "illustrated this familiar object with a picture of Maternal Beauty administering sustenance to her infant." Buffon could not have done anything like this. Buffon never, then, "arraigned the Creator for what was wanting or defective in His works;" on the contrary, whenever he has led up by an irresistible chain of reasoning to conclusions which should make men recast their ideas concerning the Deity, he invariably retreats under cover of an appeal to revelation. Naturally enough, the Sorbonne objected to an artifice which even Buffon could not conceal completely. They did not like being undermined; like Buffon himself, they preferred imposing upon the people, to seeing others do so. Buffon made his peace with the Sorbonne immediately, and, perhaps, from that time forward, contradicted himself a little more impudently than heretofore. It is probably for the reasons above suggested that Buffon did not propound a connected scheme of evolution or descent with modification, but scattered his theory in fragments up and down his work in the prefatory remarks with which he introduces the more striking animals or classes of animals. He never wastes evolutionary matter in the preface to an uninteresting animal; and the more interesting the animal, the more evolution will there be commonly found. When he comes to describe the animal more familiarly--and he generally begins a fresh chapter or half chapter when he does so--he writes no more about evolution, but gives an admirable description, which no one can fail to enjoy, and which I cannot think is nearly so inaccurate as is commonly supposed. These descriptions are the parts which Buffon intended for the general reader, expecting, doubtless, and desiring that such a reader should skip the dry parts he had been addressing to the more studious. It is true the descriptions are written _ad captandum_, as are all great works, but they succeed in captivating, having been composed with all the pains a man of genius and of great perseverance could bestow upon them. If I am not mistaken, he looked to these parts of his work to keep the whole alive till the time should come when the philosophical side of his writings should be understood and appreciated. Thus the goat breeds with the sheep, and may therefore serve as the text for a dissertation on hybridism, which is accordingly given in the preface to this animal. The presence of rudimentary organs under a pig's hoof suggests an attack upon the doctrine of final causes in so far as it is pretended that every part of every animal or plant was specially designed with a view to the wants of the animal or plant itself once and for ever throughout all time. The dog with his great variety of breeds gives an opportunity for an article on the formation of breeds and sub-breeds by man's artificial selection. The cat is not honoured with any philosophical reflections, and comes in for nothing but abuse. The hare suggests the rabbit, and the rabbit is a rapid breeder, although the hare is an unusually slow one; but this is near enough, so the hare shall serve us for the theme of a discourse on the geometrical ratio of increase and the balance of power which may be observed in nature. When we come to the carnivora, additional reflections follow upon the necessity for death, and even for violent death; this leads to the question whether the creatures that are killed suffer pain; here, then, will be the proper place for considering the sensations of animals generally. Perhaps the most pregnant passage concerning evolution is to be found in the preface to the ass, which is so near the beginning of the work as to be only the second animal of which Buffon treats after having described man himself. It points strongly in the direction of his having believed all animal forms to have been descended from one single common ancestral type. Buffon did not probably choose to take his very first opportunity in order to insist upon matter that should point in this direction; but the considerations were too important to be deferred long, and are accordingly put forward under cover of the ass, his second animal. When we consider the force with which Buffon's conclusion is led up to; the obviousness of the conclusion itself when the premises are once admitted; the impossibility that such a conclusion should be again lost sight of if the reasonableness of its being drawn had been once admitted; the position in his scheme which is assigned to it by its propounder; the persistency with which he demonstrates during forty years thereafter that the premises, which he has declared should establish the conclusion in question, are indisputable;--when we consider, too, that we are dealing with a man of unquestionable genius, and that the times and circumstances of his life were such as would go far to explain reserve and irony--is it, I would ask, reasonable to suppose that Buffon did not, in his own mind, and from the first, draw the inference to which he leads his reader, merely because from time to time he tells the reader, with a shrug of the shoulders, that _he_ draws no inferences opposed to the Book of Genesis? Is it not more likely that Buffon intended his reader to draw his inferences for himself, and perhaps to value them all the more highly on that account? The passage to which I am alluding is as follows:-- "If from the boundless variety which animated nature presents to us, we choose the body of some animal or even that of man himself to serve as a model with which to compare the bodies of other organized beings, we shall find that though all these beings have an individuality of their own, and are distinguished from one another by differences of which the gradations are infinitely subtle, there exists at the same time a primitive and general design which we can follow for a long way, and the departures from which (_dégénérations_) are far more gentle than those from mere outward resemblance. For not to mention organs of digestion, circulation, and generation, which are common to all animals, and without which the animal would cease to be an animal, and could neither continue to exist nor reproduce itself--there is none the less even in those very parts which constitute the main difference in outward appearance, a striking resemblance which carries with it irresistibly the idea of a single pattern after which all would appear to have been conceived. The horse, for example--what can at first sight seem more unlike mankind? Yet when we compare man and horse point by point and detail by detail, is not our wonder excited rather by the points of resemblance than of difference that are to be found between them? Take the skeleton of a man; bend forward the bones in the region of the pelvis, shorten the thigh bones, and those of the leg and arm, lengthen those of the feet and hands, run the joints together, lengthen the jaws, and shorten the frontal bone, finally, lengthen the spine, and the skeleton will now be that of a man no longer, but will have become that of a horse--for it is easy to imagine that in lengthening the spine and the jaws we shall at the same time have increased the number of the vertebræ, ribs, and teeth. It is but in the number of these bones, which may be considered accessory, and by the lengthening, shortening, or mode of attachment of others, that the skeleton of the horse differs from that of the human body.... We find ribs in man, in all the quadrupeds, in birds, in fishes, and we may find traces of them as far down as the turtle, in which they seem still to be sketched out by means of furrows that are to be found beneath the shell. Let it be remembered that the foot of the horse, which seems so different from a man's hand, is, nevertheless, as M. Daubenton has pointed out, composed of the same bones, and that we have at the end of each of our fingers a nail corresponding to the hoof of a horse's foot. Judge, then, whether this hidden resemblance is not more marvellous than any outward differences--whether this constancy to a single plan of structure which we may follow from man to the quadrupeds, from the quadrupeds to the cetacea, from the cetacea to birds, from birds to reptiles, from reptiles to fishes--in which all such essential parts as heart, intestines, spine, are invariably found--whether, I say, this does not seem to indicate that the Creator when He made them would use but a single main idea, though at the same time varying it in every conceivable way, so that man might admire equally the magnificence of the execution and the simplicity of the design.[46] "If we regard the matter thus, not only the ass and the horse, _but even man himself, the apes, the quadrupeds, and all animals might be regarded but as forming members of one and the same family_. But are we to conclude that within this vast family which the Creator has called into existence out of nothing, there are other and smaller families, projected as it were by Nature, and brought forth by her in the natural course of events and after a long time, of which some contain but two members, as the ass and the horse, others many members, as the weasel, martin, stoat, ferret, &c., and that on the same principle there are families of vegetables, containing ten, twenty, or thirty plants, as the case may be? If such families had any real existence they could have been formed only by crossing, by the accumulation of successive variations (_variation successive_), and by degeneration from an original type; but if we once admit that there are families of plants and animals, so that the ass may be of the family of the horse, and that the one may only differ from the other through degeneration from a common ancestor, we might be driven to admit that the ape is of the family of man, that he is but a degenerate man, and that he and man have had a common ancestor, even as the ass and horse have had. It would follow then that every family, whether animal or vegetable, had sprung from a single stock, which after a succession of generations, had become higher in the case of some of its descendants and lower in that of others." What inference could be more aptly drawn? But it was not one which Buffon was going to put before the general public. He had said enough for the discerning, and continues with what is intended to make the conclusions they should draw even plainer to them, while it conceals them still more carefully from the general reader. "The naturalists who are so ready to establish families among animals and vegetables, do not seem to have sufficiently considered the consequences which should follow from their premises, for these would limit direct creation to as small a number of forms as anyone might think fit (reduisoient le produit immédiat de la création, à un nombre d'individus aussi petit que l'on voudroit). _For if it were once shown that we had right grounds for establishing these families; if the point were once gained that among animals and vegetables there had been, I do not say several species, but even a single one, which had been produced in the course of direct descent from another species; if for example it could be once shown that the ass was but a degeneration from the horse--then there is no further limit to be set to the power of nature, and we should not be wrong in supposing that with sufficient time she could have evolved all other organized forms from one primordial type (et l'on n'auroit pas tort de supposer, que d'un seul être elle a su tirer avec le temps tous les autres êtres organisés)._" Buffon now felt that he had sailed as near the wind as was desirable. His next sentence is as follows:-- "But no! It is certain _from revelation_ that all animals have alike been favoured with the grace of an act of direct creation, and that the first pair of every species issued full formed from the hands of the Creator."[47] This might be taken as _bonâ fide_, if it had been written by Bonnet, but it is impossible to accept it from Buffon. It is only those who judge him at second hand, or by isolated passages, who can hold that he failed to see the consequences of his own premises. No one could have seen more clearly, nor have said more lucidly, what should suffice to show a sympathetic reader the conclusion he ought to come to. Even when ironical, his irony is not the ill-natured irony of one who is merely amusing himself at other people's expense, but the serious and legitimate irony of one who must either limit the circle of those to whom he appeals, or must know how to make the same language appeal differently to the different capacities of his readers, and who trusts to the good sense of the discerning to understand the difficulty of his position, and make due allowance for it. The compromise which he thought fit to put before the public was that "Each species has a type of which the principal features are engraved in indelible and eternally permanent characters, while all accessory touches vary."[48] It would be satisfactory to know where an accessory touch is supposed to begin and end. And again:-- "The essential characteristics of every animal have been conserved without alteration in their most important parts.... The individuals of each genus still represent the same forms as they did in the earliest ages, especially in the case of the larger animals" (so that the generic forms even of the larger animals prove not to be the same, but only 'especially' the same as in the earliest ages).[49] This transparently illogical position is maintained ostensibly from first to last, much in the same spirit as in the two foregoing passages, written at intervals of thirteen years. But they are to be read by the light of the earlier one--placed as a lantern to the wary upon the threshold of his work in 1753--to the effect that a single, well substantiated case of degeneration would make it conceivable that all living beings were descended from a single common ancestor. If after having led up to this by a remorseless logic, a man is found five-and-twenty years later still substantiating cases of degeneration, as he has been substantiating them unceasingly in thirty quartos during the whole interval, there should be little question how seriously we are to take him when he wishes us to stop short of the conclusions he has told us we ought to draw from the premises that he has made it the business of his life to establish--especially when we know that he has a Sorbonne to keep a sharp eye upon him. I believe that if the reader will bear in mind the twofold, serious and ironical, character of Buffon's work he will understand it, and feel an admiration for it which will grow continually greater and greater the more he studies it, otherwise he will miss the whole point. Buffon on one of the early pages of his first volume protested against the introduction of either "_plaisanterie_" or "_équivoque_" (p. 25) into a serious work. But I have observed that there is an unconscious irony in most disclaimers of this nature. When a writer begins by saying that he has "an ineradicable tendency to make things clear," we may infer that we are going to be puzzled; so when he shows that he is haunted by a sense of the impropriety of allowing humour to intrude into his work, we may hope to be amused as well as interested. As showing how far the objection to humour which he expressed upon his twenty-fifth page succeeded in carrying him safely over his twenty-sixth and twenty-seventh, I will quote the following, which begins on page twenty-six:-- "Aldrovandus is the most learned and laborious of all naturalists; after sixty years of work he has left an immense number of volumes behind him, which have been printed at various times, the greater number of them after his death. It would be possible to reduce them to a tenth part if we could rid them of all useless and foreign matter, and of a prolixity which I find almost overwhelming; were this only done, his books should be regarded as among the best we have on the subject of natural history in its entirety. The plan of his work is good, his classification distinguished for its good sense, his dividing lines well marked, his descriptions sufficiently accurate--monotonous it is true, but painstaking; the historical part of his work is less good; it is often confused and fabulous, and the author shows too manifestly the credulous tendencies of his mind. "While going over his work, I have been struck with that defect, or rather excess, which we find in almost all the books of a hundred or a couple of hundred years ago, and which prevails still among the Germans--I mean with that quantity of useless erudition with which they intentionally swell out their works, and the result of which is that their subject is overlaid with a mass of extraneous matter on which they enlarge with great complacency, but with no consideration whatever for their readers. They seem, in fact, to have forgotten what they have to say in their endeavour to tell us what has been said by other people. "I picture to myself a man like Aldrovandus, after he has once conceived the design of writing a complete natural history. I see him in his library reading, one after the other, ancients, moderns, philosophers, theologians, jurisconsults, historians, travellers, poets, and reading with no other end than with that of catching at all words and phrases which can be forced from far or near into some kind of relation with his subject. I see him copying all these passages, or getting them copied for him, and arranging them in alphabetical order. He fills many portfolios with all manner of notes, often taken without either discrimination or research, and at last sets himself to write with a resolve that not one of all these notes shall remain unused. The result is that when he comes to his account of the cow or of the hen, he will tell us all that has ever yet been said about cows or hens; all that the ancients ever thought about them; all that has ever been imagined concerning their virtues, characters, and courage; every purpose to which they have ever yet been put; every story of every old woman that he can lay hold of; all the miracles which certain religions have ascribed to them; all the superstitions they have given rise to; all the metaphors and allegories which poets have drawn from them; the attributes that have been assigned to them; the representations that have been made of them in hieroglyphics and armorial bearings, in a word all the histories and all fables in which there was ever yet any mention either of a cow or hen. How much natural history is likely to be found in such a lumber room? and how is one to lay one's hand upon the little that there may actually be?"[50] It is hoped that the reader will see Buffon, much us Buffon saw the learned Aldrovandus. He should see him going into his library, &c., and quietly chuckling to himself as he wrote such a passage as the one in which we lately found him saying that the larger animals had "especially" the same generic forms as they had always had. And the reader should probably see Daubenton chuckling also. FOOTNOTES: [39] Tom. i. p. 24, 1749. [40] Tom. i. p. 40, 1749. [41] Vol. i. p. 34, 1749. [42] Tom. i. p. 36. [43] See p. 88 of this volume; see also p. 155, and 164. [44] Tom. i. p. 33. [45] 'The Naturalist's Library,' vol. ii. p. 23, Edinburgh, 1843. [46] Tom. iv. p. 381, 1753. [47] Tom. iv. p. 383, 1753 (this was the first volume on the lower animals). [48] Tom. xiii. p. ix. 1765. [49] Sup. tom. v. p. 27, 1778. [50] Tom. i. p. 28, 1749. CHAPTER X. SUPPOSED FLUCTUATIONS OF OPINION--CAUSES OR MEANS OF THE TRANSFORMATION OF SPECIES. Enough, perhaps, has been already said to disabuse the reader's mind of the common misconception of Buffon, namely, that he was more or less of an elegant trifler with science, who cared rather about the language in which his ideas were clothed than about the ideas themselves, and that he did not hold the same opinions for long together; but the accusation of instability has been made in such high quarters that it is necessary to refute it still more completely. Mr. Darwin, for example, in his "Historical Sketch of the Recent Progress of Opinion on the Origin of Species" prefixed to all the later editions of his own 'Origin of Species,' says of Buffon that he "was the first author who, in modern times, has treated" the origin of species "in a scientific spirit. But," he continues, "as his opinions fluctuated greatly at different periods, and as he does not enter on the causes or means of the transformation of species, I need not here enter on details."[51] Mr. Darwin seems to have followed the one half of Isidore Geoffroy St. Hilaire's "full account of Buffon's conclusions" upon the subject of descent with modification,[52] to which he refers with approval on the second page of his historical sketch.[53] Turning, then, to Isidore Geoffroy's work, I find that in like manner he too has been following the one half of what Buffon actually said. But even so, he awards Buffon very high praise. "Buffon," he writes, "is to the doctrine of the mutability of species what Linnæus is to that of its fixity. It is only since the appearance of Buffon's 'Natural History,' and in consequence thereof, that the mutability of species has taken rank among scientific questions."[54] . . . . . . "Buffon, who comes next in chronological order after Bacon, follows him in no other respect than that of time. He is entirely original in arriving at the doctrine of the variability of organic types, and in enouncing it after long hesitation, during which one can watch the labour of a great intelligence freeing itself little by little from the yoke of orthodoxy. "But from this source come difficulties in the interpretation of Buffon's work which have misled many writers. Buffon expresses absolutely different opinions in different parts of his natural history--so much so that partisans and opponents of the doctrine of the fixity of species have alike believed and still believe themselves at liberty to claim Buffon as one of the great authorities upon their side." Then follow the quotations upon which M. Geoffroy relies--to which I will return presently--after which the conclusion runs thus:-- "The dates, however, of the several passages in question are sufficient to explain the differences in their tenor, in a manner worthy of Buffon. Where are the passages in which Buffon affirms the immutability of species? At the beginning of his work. His first volume on animals[55] is dated 1753. The two following are those in which Buffon still shares the views of Linnæus; they are dated 1755 and 1756. Of what date are those in which Buffon declares for variability? From 1761 to 1766. And those in which, after having admitted variability and declared in favour of it, he proceeds to limit it? From 1765 to 1778. "The inference is sufficiently simple. Buffon does but correct himself. He does not fluctuate. He goes once for all from one opinion to the other, from what he accepted at starting on the authority of another to what he recognized as true after twenty years of research. If while trying to set himself free from the prevailing notions, he in the first instance went, like all other innovators, somewhat to the opposite extreme, he essays as soon as may be to retrace his steps in some measure, and thenceforward to remain unchanged. "Let the reader cast his eye over the general table of contents wherein Buffon, at the end of his 'Natural History,' gives a _résumé_ of all of it that he is anxious to preserve. He passes over alike the passages in which he affirms and those in which he unreservedly denies the immutability of species, and indicates only the doctrine of the permanence of essential features and the variability of details (toutes les touches accessoires); he repeats this eleven years later in his 'Époques de la Nature'" (published 1778).[56] But I think I can show that the passages which M. Geoffroy brings forward, to prove that Buffon was in the first instance a supporter of invariability, do not bear him out in the deduction he has endeavoured to draw from them. "What author," he asks, "has ever pronounced more decidedly than Buffon in favour of the invariability of species? Where can we find a more decided expression of opinion than the following? "'The different species of animals are separated from one another by a space which Nature cannot overstep.'" On turning, however, to Buffon himself, I find the passage to stand as follows:-- "_Although_ the different species of animals are separated from one another by a space which Nature cannot overstep--_yet some of them approach so nearly to one another in so many respects that there is only room enough left for the getting in of a line of separation between them_,"[57] and on the following page he distinctly encourages the idea of the mutability of species in the following passage:-- "In place of regarding the ass as a degenerate horse, there would be more reason in calling the horse a more perfect kind of ass (un âne perfectionné), and the sheep a more delicate kind of goat, that we have tended, perfected, and propagated for our use, and that the more perfect animals in general--especially the domestic animals--_draw their origin from some less perfect species of that kind of wild animal which they most resemble. Nature alone not being able to do as much as Nature and man can do in concert with one another_."[58] But Buffon had long ago declared that if the horse and the ass could be considered as being blood relations there was no stopping short of the admission that all animals might also be blood relations--that is to say, descended from common ancestors--and now he tells us that the ass and horse _are_ in all probability descended from common ancestors. Will a reader of any literary experience hold that so laborious, and yet so witty a writer, and one so studious of artistic effect, could ignore the broad lines he had laid down for himself, or forget how what he had said would bear on subsequent passages, and subsequent passages on it? A less painstaking author than Buffon may yet be trusted to remember his own work well enough to avoid such literary bad workmanship as this. If Buffon had seen reason to change his mind he would have said so, and would have contradicted the inference he had originally pronounced to be deducible from an admission of kinship between the ass and the horse. This, it is hardly necessary to say, he never does, though he frequently thinks it well to remind his reader of the fact that the ass and the horse are in all probability closely related. This is bringing two and two together with sufficient closeness for all practical purposes. Should not M. Geoffroy's question, then, have rather been "Who has ever pronounced more grudgingly, even in an early volume, &c., &c., and who has more completely neutralized whatever concession he might appear to have been making?" Nor does the only other passage which M. Geoffroy brings forward to prove that Buffon was originally a believer in the fixity of species bear him out much better. It is to be found on the opening page of a brief introduction to the wild animals. M. Geoffroy quotes it thus: "We shall see Nature dictating her laws, so simple yet so unchangeable, and imprinting her own immutable characters upon every species." But M. Geoffroy does not give the passage which, on the same page, admits mutability among domesticated animals, in the case of which he declares we find Nature "rarement perfectionnée, souvent alterée, défigurée;" nor yet does he deem it necessary to show that the context proves that this unchangeableness of wild animals is only relative; and this he should certainly have done, for two pages later on Buffon speaks of the American tigers, lions, and panthers as being "degenerated, if their original nature was cruel and ferocious; or, rather, they have experienced the effect of climate, and under a milder sky have assumed a milder nature, their excesses have become moderated, and by the changes which they have undergone they have become more in conformity with the country they inhabit."[59] And again:-- "If we consider each species in the different climates which it inhabits, we shall find perceptible varieties as regards size and form: they all derive an impress to a greater or less extent from the climate in which they live. _These changes are only made slowly and imperceptibly._ Nature's great workman is Time. He marches ever with an even pace, and does nothing by leaps and bounds, but by degrees, gradations, and succession he does all things; and the changes which he works--at first imperceptible--become little by little perceptible, and show themselves eventually in results about which there can be no mistake. "Nevertheless animals in a free, wild state are perhaps less subject than any other living beings, man not excepted, to alterations, changes, and variations of all kinds. Being free to choose their own food and climate, they vary less than domestic animals vary."[60] The conditions of their existence, in fact, remaining practically constant, the animals are no less constant themselves. The writer of the above could hardly be claimed as a very thick and thin partisan of immutability, even though he had not shown from the first how clearly he saw that there was no middle position between the denial of all mutability, and the admission that in the course of sufficient time any conceivable amount of mutability is possible. I will give a considerable part of what I have found in the first six volumes of Buffon to bear one way or the other on his views concerning the mutability of species; and I think the reader, so far from agreeing with M. Isidore Geoffroy that Buffon began his work with a belief in the fixity of species, will find, that from the very first chapter onward, he leant strongly to mutability, even if he did not openly avow his belief in it. In support of this assertion, one quotation must suffice:-- "Nature advances by gradations which pass unnoticed. She passes from one species, and often from one genus to another by imperceptible degrees, so that we meet with a great number of mean species and objects of such doubtful characters that we know not where to place them."[61] The reader who turns to Buffon himself will find the idea that Buffon took a less advanced position in his old age than he had taken in middle life is also without foundation. Mr. Darwin has said that Buffon "does not enter into the causes or means of the transformation of species." It is not easy to admit the justice of this. Independently of his frequently insisting on the effect of all kinds of changed surroundings, he has devoted a long chapter of over sixty quarto pages to this very subject; it is to be found in his fourteenth volume, and is headed "De la Dégénération des Animaux," of which words "On descent with modification" will be hardly more than a literal translation. I shall give a fuller but still too brief outline of the chapter later on, and will confine myself here to saying that the three principal causes of modification which Buffon brings forward are changes of climate, of food, and the effects of domestication. He may be said to have attributed variation to the direct and specific action of changed conditions of life, and to have had but little conception of the view which he was himself to suggest to Dr. Erasmus Darwin, and through him to Lamarck. Isidore Geoffroy, writing of Lamarck, and comparing his position with that taken by Buffon, says, on the whole truly, that "what Buffon ascribes to the general effects of climate, Lamarck maintains to be caused, especially in the case of animals, by the force of habits; _so that, according to him, they are not, properly speaking, modified by the conditions of their existence, but are only induced by these conditions to set about modifying themselves_."[62] But it is very hard to say how much Buffon saw and how much he did not see. He may be trusted to have seen that if he once allowed the thin end of this wedge into his system, he could no more assign limits to the effect which living forms might produce upon their own organisms by effort and ingenuity in the course of long time, than he could set limits to what he had called the power of Nature if he was once to admit that an ass and a horse might, through that power, have been descended from a common ancestor. Nevertheless, he shows no unwillingness or recalcitrancy about letting the wedge enter, for he speaks of domestication as inducing modifications "sufficiently profound to become constant and hereditary in successive generations ... _by its action on bodily habits it influences also their natures, instincts, and most inward qualities_."[63] This is a very thick thin end to have been allowed to slip in unawares; but it is astonishing how little Buffon can see when he likes. I hardly doubt but he would have been well enough pleased to have let the wedge enter still farther, but this fluctuating writer had assigned himself his limits some years before, and meant adhering to them. Again, in this very chapter on Degeneration, to which M. Geoffroy has referred, there are passages on the callosities on a camel's knees, on the llama, and on the haunches of pouched monkeys which might have been written by Dr. Darwin himself.[64] They will appear more fully presently. Buffon now probably felt that he had said enough, and that others might be trusted to carry the principle farther when the time was riper for its enforcement. FOOTNOTES: [51] 'Origin of Species,' p. xiii. ed. 1876. [52] 'Hist. Nat. Gén.,' tom. ii. p. 405, 1859. [53] 'Origin of Species,' p. xiv. 1876. [54] 'Hist. Nat. Gén.,' tom. ii. p. 383. [55] Tom. iv. [56] 'Hist. Nat. Gén.,' tom. ii. p. 391, 1859. [57] Tom. v. p. 59, 1755. [58] Tom. v. p. 60. [59] Tom. vi. p. 58, 1756. [60] Tom. vi. pp. 59-60, 1756. [61] Tom. i. p. 13, 1749. [62] 'Hist. Nat. Gén.,' tom. ii. p. 411, 1859. [63] Tom. xi. p. 290, 1764 (misprinted on title-page 1754). [64] See tom. xiv. p. 326, 1766; and p. 162 of this volume. CHAPTER XI. BUFFON--FULLER QUOTATIONS. Let us now proceed to those fuller quotations which may answer the double purpose of bearing me out in the view of Buffon's work which I have taken in the foregoing pages, and of inducing the reader to turn to Buffon himself. I have already said that from the very commencement of his work Buffon showed a proclivity towards considerations which were certain to lead him to a theory of evolution, even though he had not, as I believe he had, already taken a more comprehensive view of the subject than he thought fit to proclaim unreservedly. In 1749, at the beginning of his first volume he writes:-- "The first truth that makes itself apparent on serious study of Nature, is one that man may perhaps find humiliating; it is this--that he, too, must take his place in the ranks of animals, being, as he is, an animal in every material point. It is possible also that the instinct of the lower animals will strike him as more unerring, and their industry more marvellous than his own. Then, running his eye over the different objects of which the universe is composed, he will observe with astonishment that we can descend by almost imperceptible degrees from the most perfect creature to the most formless matter--from the most highly organized animal to the most entirely inorganic substance. He will recognize this gradation as the great work of Nature; and he will observe it not only as regards size and form, but also in respect of movements, and in the successive generations of every species.[65] "Hence," he continues, "arises the difficulty of arriving at any perfect system or method in dealing either with Nature as a whole or even with any single one of her subdivisions. The gradations are so subtle that we are often obliged to make arbitrary divisions. Nature knows nothing about our classifications, and does not choose to lend herself to them without reserve. We therefore see a number of intermediate species and objects which it is very hard to classify, and which of necessity derange our system whatever it may be."[66] "The attempt to form perfect systems has led to such disastrous results that it is now more easy to learn botany than the terminology which has been adopted as its language."[67] After saying that "_la marche de la Nature_" has been misunderstood, and that her progress has ever been by a succession of slow steps, he maintains that the only proper course is to class together whatever objects resemble one another, and to separate those which are unlike. If individual specimens are absolutely alike, or differ so little that the differences can hardly be perceived, they must be classed as of the same species; if the differences begin to be perceptible, but if at the same time there is more resemblance than difference, the individuals presenting these features should be classed as of a different species, but as of the same genus; if the differences are still more marked, but nevertheless do not exceed the resemblances, then they must be taken as not only specific but generic, though as not sufficient to warrant the individuals in which they appear, being placed in different classes. If they are still greater, then the individuals are not even of the same class; but it should be always understood that the resemblances and differences are to be considered in reference to the entirety of the plant or animal, and not in reference to any particular part only.[68] The two rocks which are equally to be avoided are, on the one hand, absence of method, and, on the other, a tendency to over-systematize.[69] Like Dr. Erasmus Darwin, and more recently Mr. Francis Darwin, Buffon is more struck with the resemblances than with the differences between animals and plants, but he supposes the vegetable kingdom to be a continuation of the animal, extending lower down the scale, instead of holding as Dr. Darwin did, that animals and vegetables have been contemporaneous in their degeneration from a common stock. "We see," he writes, "that there is no absolute and essential difference between animals and vegetables, but that Nature descends by subtle gradations from what we deem the most perfect animal to one which is less so, and again from this to the vegetable. The fresh-water polypus may perhaps be considered as the lowest animal, and as at the same time the highest plant."[70] Looking to the resemblances between animals and plants, he declares that their modes of reproduction and growth involve such close analogy that no difference of an essential nature can be admitted between them.[71] On the other hand, Buffon appears, at first sight, to be more struck with the points of difference between the mental powers of the lower animals and man than with those which they present in common. It is impossible, however, to accept this as Buffon's real opinion, on the strength of isolated passages, and in face of a large number of others which point stealthily but irresistibly to an exactly opposite conclusion. We find passages which show a clear apprehension of facts that the world is only now beginning to consider established, followed by others which no man who has kept a dog or cat will be inclined to agree with. I think I have already explained this sufficiently by referring it to the impossibility of his taking any other course under the circumstances of his own position and the times in which he lived. Buffon does not deal with such pregnant facts, as, for example, the geometrical ratio of increase, in such manner as to suggest that he was only half aware of their importance and bearing. On the contrary, in the very middle of those passages which, if taken literally, should most shake confidence in his judgment, there comes a sustaining sentence, so quiet that it shall pass unnoticed by all who are not attentive listeners, yet so encouraging to those who are taking pains to understand their author that their interest is revived at once. Thus, he has insisted, and means insisting much further, on the many points of resemblance between man and the lower animals, and it has now become necessary to neutralize the effect of what he has written upon the minds of those who are not yet fitted to see instinct and reason as differentiations of a single faculty. He accordingly does this, and, as is his wont, he does it handsomely; so handsomely that even his most admiring followers begin to be uncomfortable. Whereon he begins his next paragraph with "Animals have excellent senses, but not _generally, all of them_, as good as man's."[72] We have heard of damning with faint praise. Is not this to praise with faint damnation? Yet we can lay hold of nothing. It was not Buffon's intention that we should. An ironical writer, concerning whom we cannot at once say whether he is in earnest or not, is an actor who is continually interrupting his performance in order to remind the spectator that he is acting. Complaint, then, against an ironical writer on the score that he puzzles us, is a complaint against irony itself; for a writer is not ironical unless he puzzles. He should not puzzle unless he believes that this is the best manner of making his reader understand him in the end, or without having a _bonne bouche_ for those who will be at the pains to puzzle over him; and he should make it plain that for long parts of his work together he is to be taken according to the literal interpretation of his words; but if he has observed the above duly, he is a successful or unsuccessful writer according as he puzzles or fails to do so, and should be praised or blamed accordingly. To condemn irony entirely, is to say that there should be no people allowed to go about the world but those to whom irony would be an impertinence. Having already in some measure reassured us by the faintness with which he disparages the senses of the lower animals, Buffon continues, that these senses, whether in man or in animals, may be greatly developed by exercise: which we may suppose that a man of even less humour than Buffon must know to be great nonsense, unless it be taken to involve that animals as well as man can reflect and remember; it now, therefore, becomes necessary to reassure the other side, and to maintain that animals cannot reflect, and have no memory. "_Je crois_," he writes, "_qu'on peut démontrer que les animaux n'ont aucune connaissance du passé, aucune idée du temps, et que par conséquent ils n'ont pas la mémoire_."[73] I am ashamed of even arguing seriously against the supposition that this was Buffon's real opinion. The very sweepingness of the assertion, the baldness, and I might say brutality with which it is made, are convincing in their suggestiveness of one who is laughing very quietly in his sleeve. "Society," he continues, later on, "considered even in the case of a single human family, involves the power of reason; it involves feeling in such of the lower animals as form themselves into societies freely and of their own accord, but it involves nothing whatever in the case of bees, who have found themselves thrown together through no effort of their own. Such societies can only be, and it is plain have only been, the results--neither foreseen, nor ordained, nor conceived by those who achieve them--of the universal mechanism and of the laws of movement established by the Creator."[74] A hive of bees, in fact, is to be considered as composed of "ten thousand animated automata."[75] Years later he repeats these views with little if any modification.[76] A still more remarkable passage is to be found a little farther on. "If," he asks, "animals have neither understanding, mind, nor memory, if they are wholly without intelligence, and if they are limited to the exercise and experience of feeling only," and it must be remembered that Buffon has denied all these powers to the inferior animals, "whence comes that remarkable prescient instinct which so many of them exhibit? Is the mere power of feeling sensations sufficient to make them garner up food during the summer, on which food they may subsist in winter? Does not this involve the power of comparing dates, and the idea of a coming future, an '_inquiétude raisonnée_'? Why do we find in the hole of the field-mouse enough acorns to keep him until the following summer? Why do we find such an abundant store of honey and wax within the bee-hive? Why do ants store food? Why should birds make nests if they do not know that they will have need of them? Whence arise the stories that we hear of the wisdom of foxes, which hide their prey in different spots, that they may find it at their need and live upon it for days together? Or of the subtilty of owls, which husband their store of mice by biting off their feet, so that they cannot run away? Or of the marvellous penetration of bees, which know beforehand that their queen should lay so many eggs in such and such a time, and that so many of these eggs should be of a kind which will develop into drones, and so many more of such another kind as should become neuters; and who in consequence of this their foreknowledge build so many larger cells for the first, and so many smaller for the second?"[77] Buffon answers these questions thus:-- "Before replying to them," he says, "we should make sure of the facts themselves;--are they to be depended upon? Have they been narrated by men of intelligence and philosophers, or are they popular fables only?" (How many delightful stories of the same character does he not soon proceed to tell us himself). "I am persuaded that all these pretended wonders will disappear, and the cause of each one of them be found upon due examination. But admitting their truth for a moment, and granting to the narrators of them that animals have a presentiment, a forethought, and even a certainty concerning coming events, does it therefore follow that this should spring from intelligence? If so, theirs is assuredly much greater than our own. For our foreknowledge amounts to conjecture only; the vaunted light of our reason doth but suffice to show us a little probability; whereas the forethought of animals is unerring, and must spring from some principle far higher than any we know of through our own experience. Does not such a consequence, I ask, _prove repugnant alike to religion and common sense_?"[78] This is Buffon's way. Whenever he has shown us clearly what we ought to think, he stops short suddenly on religious grounds. It is incredible that the writer who at the very commencement of his work makes man take his place among the animals, and who sees a subtle gradation extending over all living beings "from the most perfect creature"--who must be man--"to the most entirely inorganic substance"--I say it is incredible that such a writer should not see that he had made out a stronger case in favour of the reason of animals than against it. According to him, the test whether a thing is to have such and such a name is whether it looks fairly like other things to which the same name is given; if it does, it is to have the name; if it does not, it is not. No one accepted this lesson more heartily than Dr. Darwin, whose shrewd and homely mind, if not so great as Buffon's, was still one of no common order. Let us see the view he took of this matter. He writes:-- "If we were better acquainted with the histories of those insects which are formed into societies, as the bees, wasps, and ants, I make no doubt but we should find that their arts and improvements are not so similar and uniform as they now appear to us, but that they arose in the same manner from experience and tradition, as the arts of our own species; though their reasoning is from fewer ideas, is busied about fewer objects, and is executed with less energy."[79] And again, a little later:-- "According to the late observations of Mr. Hunter, it appears that beeswax is not made from the dust of the anthers of flowers, which they bring home on their thighs, but that this makes what is termed bee-bread, and is used for the purpose of feeding the bee-maggots; in the same way butterflies live on honey, but the previous caterpillar lives on vegetable leaves, while the maggots of large flies require flesh for their food. What induces the bee, who lives on honey, to lay up vegetable powder for its young? What induces the butterfly to lay its eggs on leaves when itself feeds on honey?... If these are not deductions from their own previous experience or observation, all the actions of mankind must be resolved into instincts."[80] Or again:-- "Common worms stop up their holes with leaves or straws to prevent the frost from injuring them, or the centipes from devouring them. The habits of peace or the stratagems of war of these subterranean nations are covered from our view; but a friend of mine prevailed on a distressed worm to enter the hole of another worm on a bowling green, and he presently returned much wounded about the head, ... which evinces they have design in stopping the mouths of their habitations."[81] Does it not look as if Dr. Darwin had in his mind the very passage of Buffon which I have been last quoting? and is it likely that the facts which were accepted by Dr. Darwin without question, or the conclusions which were obvious to him, were any less accepted by or obvious to Buffon? _The Goat--Hybridism._ In his prefatory remarks upon the goat, Buffon complains of the want of systematic and certified experiment as to what breeds and species will be fertile _inter se_, and with what results. The passage is too long to quote, but is exceedingly good, and throughout involves belief in a very considerable amount of modification in the course of successive generations. I may give the following as an example:-- "We do not know whether or no the zebra would breed with the horse or ass--whether the large-tailed Barbary sheep would be fertile if crossed with our own--whether the chamois is not a wild goat; and whether it would not form an intermediate breed if crossed with our domesticated goats; we do not know whether the differences between apes are really specific, or whether apes are not like dogs, one single species, of which there are many different breeds.... Our ignorance concerning all these facts is almost inevitable, as the experiments which would decide them require more time, pains, and money than can be spared from, the life and fortune of an ordinary man. I have spent many years in experiments of this kind, and will give my results when I come to my chapter on mules; but I may as well say at once that they have thrown but little light upon the subject, and have been for the most part unsuccessful."[82] "But these," he continues, "are the very points which must determine our whole knowledge concerning animals, their right division into species, and the true understanding of their history." He proposes therefore, in the present lack of knowledge, "to regard all animals as different species which do not breed together under our eyes," and to leave time and experiment to correct mistakes.[83] _The Pig--Doctrine of Final Causes._ We have seen that the doctrine of the mutability of species has been unfortunately entangled with that of final causes, or the belief that every organ and every part of each animal or plant has been designed to serve some purpose useful to the animal, and this not only useful at some past time, but useful now, and for all time to come. He who believes species to be mutable will see in many organs signs of the history of the individual, but nothing more. Buffon, as I have said, is explicit in his denial of final causes in the sense expressed above. After pointing out that the pig is an animal whose relation to other animals it is difficult to define, he says:-- "In a word, it is of a nature altogether equivocal and ambiguous, or, rather, it must appear so to those who believe the hypothetical order of their own ideas to be the real order of things, and who see nothing in the infinite chain of existences but a few apparent points to which they will refer everything. "But we cannot know Nature by inclosing her action within the narrow circle of our own thoughts.... Instead of limiting her action, we should extend it through immensity itself; we should regard nothing as impossible, but should expect to find all things--supposing that all things are possible--nay, _are_. Doubtful species, then, irregular productions, anomalous existences will henceforth no longer surprise us, and will find their place in the infinite order of things as duly as any others. They fill up the links of the chain; they form knots and intermediate points, and also they mark its extremities: they are of especial value to human intelligence, as providing it with cases in which Nature, being less in conformity with herself, is taken more unawares, so that we can recognize singular characters and fleeting traits which show us that her ends are much more general than are our own views of those ends, and that, though she does nothing in vain, yet she does but little with the designs which we ascribe to her."[84] "The pig," he continues, "is not formed on an original, special, and perfect type; its type is compounded of that of many other animals. It has parts which are evidently useless, or which at any rate it cannot use--such as toes, all the bones of which are perfectly formed but which are yet of no service to it. Nature then is far from subjecting herself to final causes in the composition of her creatures. Why should she not sometimes add superabundant parts, seeing she so often omits essential ones?" "How many animals are there not which lack sense and limbs? Why is it considered so necessary that every part in an individual should be useful to the other parts and to the whole animal? Should it not be enough that they do not injure each other nor stand in the way of each other's fair development? All parts coexist which do not injure each other enough to destroy each other, and perhaps in the greater number of living beings the parts which must be considered as relative, useful, or necessary, are fewer than those which are indifferent, useless, and superabundant. But we--ever on the look out to refer all parts to a certain end--when we can see no apparent use for them suppose them to have hidden uses, and imagine connections which are without foundation, and serve only to obscure our perception of Nature as she really is: we fail to see that we thus rob philosophy of her true character, which is to inquire into the 'how' of things--into the manner in which Nature acts--and that we substitute for this true object a vain idea, seeking to divine the 'why'--the ends which she has proposed in acting."[85] _The Dog--Varieties in consequence of Man's Selection._ "Of all animals the dog is most susceptible of impressions, and becomes most easily modified by moral causes. He is also the one whose nature is most subject to the variations and alterations caused by physical influences: he varies to a prodigious extent, in temperament, mental powers, and in habits: his very form is not constant;" ... but presents so many differences that "dogs have nothing in common but conformity of interior organization, and the power of interbreeding freely."... ... "How then can we detect the characters of the original race? How recognize the effects produced by climate, food, &c.? How, again, distinguish these from those other effects which come from the intermixture of races, either when wild or in a state of domestication? All these causes, in the course of time, alter even the most constant forms, so that the imprint of Nature does not preserve its sharpness in races which man has dealt with largely. Those animals which are free to choose climate and food for themselves can best conserve their original character, ... but those which man has subjected to his own influence--which he has taken with him from clime to clime, whose food, habits, and manner of life he has altered--must also have changed their form far more than others; and as a matter of fact we find much greater variety in the species of domesticated animals than in those of wild ones. Of all these, however, the dog is the one most closely attached to man, living like man the least regular manner of life; he is also the one whose feelings so master him as to make him docile, obedient, susceptible of every kind of impression, and even of every kind of constraint; it is not surprising, then, that he should of all animals present us with the greatest variety in shape, stature, colour, and all physical and mental qualities." Here again the direct cause of modification is given as being the inner feelings of the animal modified, change of conditions being the indirect cause as with Dr. Erasmus Darwin and Lamarck. "Other circumstances, however, concur to produce these results. The dog is short-lived: he breeds often and freely: he is perpetually under the eye of man; hence when--by some chance common enough with Nature--a variation or special feature has made its appearance, man has tried to perpetuate it by uniting together the individuals in which it has appeared, as people do now who wish to form new breeds of dogs and other animals. Moreover, though species were all formed at the same time, yet the number of generations since the creation has been much greater in the short-lived than in the long-lived species: hence variations, alterations, and departure from the original type, may be expected to have become more perceptible in the case of animals which are so much farther removed from their original stock. "Man is now eight times nearer Adam than the dog is to the first dog--for man lives eighty years, while the dog lives but ten. If, then, these species have an equal tendency to depart from their original type, the departure should be eight times more apparent with the dog than with man."[86] Here follow remarks upon the great variability of ephemeral insects and of animal plants, on the impossibility of discovering the parent-stock of our wheat and of others of our domesticated plants,[87] and on the tendency of both plants and animals to resume feral characteristics on becoming wild again after domestication.[88] _The Hare--Geometrical Ratio of Increase._ We have already seen that it was Buffon's pleasure to consider the hare a rabbit for the time being, and to make it the text for a discourse upon fecundity. I have no doubt he enjoyed doing this, and would have found comparatively little pleasure in preaching the same discourse upon the rabbit. Speaking of the way in which even the races of mankind have struggled and crowded each other out, Buffon says:-- "These great events--these well-marked epochs in the history of the human race--are yet but ripples, as it were, on the current of life; which, as a general rule, flows onward evenly and in equal volume. "It may be said that the movement of Nature turns upon two immovable pivots--one, the illimitable fecundity which she has given to all species; the other, the innumerable difficulties which reduce the results of that fecundity, and leave throughout time nearly the same quantity of individuals in every species.[89]... Taking the earth as a whole, and the human race in its entirety, the numbers of mankind, like those of animals, should remain nearly constant throughout time; for they depend upon an equilibrium of physical causes which has long since been reached, and which neither man's moral nor his physical efforts can disturb, inasmuch as these moral efforts do but spring from physical causes, of which they are the special effects. No matter what care man may take of his own species, he can only make it more abundant in one place by destroying it or diminishing its numbers in another. When one part of the globe is overpeopled, men emigrate, spread themselves over other countries, destroy one another, and establish laws and customs which sometimes only too surely prevent excess of population. In those climates where fecundity is greatest, as in China, Egypt, and Guinea, they banish, mutilate, sell, or drown infants. Here, we condemn them to a perpetual celibacy. Those who are in being find it easy to assert rights over the unborn. Regarding themselves as the necessary, they annihilate the contingent, and suppress future generations for their own pleasure and advantage. Man does for his own race, without perceiving it, what he does also for the inferior animals: that is to say, he protects it and encourages it to increase, or neglects it according to his sense of need--according as advantage or inconvenience is expected as the consequence of either course. And since all these moral effects themselves depend upon physical causes, which have been in permanent equilibrium ever since the world was formed, it follows that the numbers of mankind, like those of animals, should remain constant. "Nevertheless, this fixed state, this constant number, is not absolute, all physical and moral causes, and all the results which spring from them, balance themselves, as though, upon a see-saw, which has a certain play, but never so much as that equilibrium should be altogether lost. As everything in the universe is in movement, and as all the forces which are contained in matter act one against the other and counterbalance one another, all is done by a kind of oscillation; of which the mean points are those to which we refer as being the ordinary course of nature, while the extremes are the periods which deviate from that course most widely. And, as a matter of fact, with animals as much as with plants, a time of unusual fecundity is commonly followed by one of sterility; abundance and dearth come alternately, and often at such short intervals that we may foretell the production of a coming year by our knowledge of the past one. Our apples, pears, oaks, beeches, and the greater number of our fruit and forest trees, bear freely but about one year in two. Caterpillars, cockchafers, woodlice, which in one year may multiply with great abundance, will appear but sparsely in the next. What indeed would become of all the good things of the earth, what would become of the useful animals, and indeed of man himself, if each individual in these years of excess was to leave its quotum of offspring? This, however, does not happen, for destruction and sterility follow closely upon excessive fecundity, and, independently of the contagion which follows inevitably upon overcrowding, each species has its own special sources of death and destruction, which are of themselves sufficient to compensate for excess in any past generation. "Nevertheless the foregoing should not be taken in an absolute sense, nor yet too strictly,--especially in the case of those races which are not left entirely to the care of Nature. Those which man takes care of--commencing with his own--are more abundant than they would be without his care, yet, as his power of taking this care is limited, the increase which has taken place is also fixed, and has long been restrained within impassable boundaries. Again, though in civilized countries man, and all the animals useful to him, are more numerous than in other places, yet their numbers never become excessive, for the same power which brings them into being destroys them as soon as they are found inconvenient."[90] _The Carnivora--Sensation._ Buffon begins his seventh volume with some remarks on the _carnivora_ in general, which I would gladly quote at fuller length than my space will allow. He dwells on the fact that the number, as well as the fecundity of the insect races is greater than that of the mammalia, and even than of plants; and he points out that "violent death is almost as necessary an usage as is the law that we must all, in one way or another, die." This leads him to the question whether animals can feel. "To speak seriously," (au réel) he says (and why this, if he had always spoken seriously?[91]), "can we doubt that those animals whose organization resembles our own, feel the same sensations as we do? They must feel, for they have senses, and they must feel more and more in proportion as their senses are more active and more perfect." Those whose organ of any sense is imperfect, have but imperfect perception in respect of that sense; and those that are entirely without the organ want also all corresponding sensation. "Movement is the necessary consequence of acts of perception. I have already shown that in whatever manner a living being is organized, if it has perceptions at all, it cannot fail to show that it has them by some kind of movement of its body. Hence plants, though highly organized, have no feeling, any more than have those animals which, like plants, manifest no power of motion. Among animals there are those which, like the sensitive plant, have but a certain power of movement about their own parts, and which have no power of locomotion; such animals have as yet but little perception. Those, again, which have power of locomotion, but which, like automata, do but a small number of things, and always after the same fashion, can have only small powers of perception, and these limited to a small number of objects. But in the case of man, what automata, indeed, have we not here! How much do not education and the intercommunication of ideas increase our powers and vivacity of perception. What difference can we not see in this respect between civilized and uncivilized races, between the peasant girl, and the woman of the world? And in like manner among animals, those which live with us have their perceptions increased in range, while those that are wild have but their natural instinct, which is often more certain but always more limited in range than is the intelligence of domesticated animals."[92] . . . . . . "For perception to exist in its fullest development in any animal body, that body must form a whole--an _ensemble_, which shall not only be capable of feeling in all its parts, but shall be so arranged that all these feeling parts shall have a close correspondence with one another, and that no one of them can be disturbed without communicating a portion of that disturbance to every other part. There must also be a single chief centre, with which all these different disturbances may be connected, and from which, as from a common _point d'appui_, the reactions against them may take their rise. Hence man, and those animals whose organization most resembles man's, will be the most capable of perceptions, while those whose unity is less complete, whose parts have a less close correspondence with each other--which have several centres of sensation, and which seem, in consequence, less to envelope a single existence in a single body than to contain many centres of existence separated and different from one another--these will have fewer and duller perceptions. The polypus, which can be reproduced by fission; the wasp, whose head even after separation from the body still moves, lives, acts, and even eats as heretofore; the lizard which we deprive neither of sensation nor movement by cutting off part of its body; the lobster which can restore its amputated limbs; the turtle whose heart beats long after it has been plucked out, in a word all the animals whose organization differs from our own, have but small powers of perception, and the smaller the more they differ from us."[93] This is Buffon's way of satirizing our inability to bear in mind that we are compelled to judge all things by our own standards. He also wishes to reassure those who might be alarmed at the tendency of some of his foregoing remarks, and who he knew would find comfort in being told that a thing which does not express itself as they do does not feel at all. The diaphragm according to Buffon appears to be the centre of the powers of sensation; the slightest injury "even to the attachments of the diaphragm is followed by strong convulsions, and even by death. The brain which has been called the seat of 'sensations' is yet not the centre of 'perception,' since we can wound it, and even take considerable parts of it away, without death's ensuing, and without preventing an animal from living, moving and feeling in all its parts." Buffon thus distinguishes between "sensation" and "perception." "Sensation," he says, "is simply the activity of a sense, but perception is the pleasantness or unpleasantness of this sensation," "perceived by its being propagated and becoming active throughout the entire system." I have therefore several times, when translating from Buffon, rendered the word "_sentiment_" by "perception," and shall continue to do so. "I say," writes Buffon, "the pleasantness or unpleasantness, because this is the very essence of perception; the one feature of perception consists in perceiving either pain or pleasure; and though movements which do not affect us in either one or the other of these two ways may indeed take place within us, yet we are indifferent to them, and do not perceive that we are affected by them. All external movement, and all exercise of the animal powers, spring from perception; its action is proportionate to the extent of its excitation, to the extent of the feeling which is being felt.[94] And this same part, which we regard as the centre of sensation, will also be that of all the animal powers; or, if it is preferred to call it so, it will be the common _point d'appui_ from which they all take rise. The diaphragm is to the animal what the 'stock' is to the plant; both divide an organism transversely, both serve as the _point d'appui_ of opposing forces; for the forces which push upward those parts of a tree which should form its trunk and branches, bear upon and are supported by the 'stock,' as do those opposing forces, which drive the roots downwards. . . . . . . "Even on a cursory examination we can see that all our innermost affections, our most lively emotions, our most expansive moments of delight, and, on the other hand, our sudden starts, pains, sicknesses, and swoons--in fact, all our strong impressions concerning the pleasure or pain of any sensation--make themselves felt within the body, and about the region of the diaphragm. The brain, on the contrary, shows no sign of being a seat of perception. In the head there are pure sensations and nothing else, or rather, there are but the representations of sensations stripped of the character of perception; that is to say, we can remember and call to mind whether such and such a sensation was pleasant to us or otherwise, and if this operation, which goes on in the head, is followed by a vivid perception, then the impression made is perceived in the interior of the body, and always in the region of the diaphragm. Hence, in the foetus where this membrane is without use, there is no perception, or so little that nothing comes of it, the movements of the foetus, such as they are, being rather mechanical than dependent on sensation and will. "Whatever the matter may be which serves as the vehicle of perception, and produces muscular movement, it is certain that it is propagated through the nerves, and that it communicates itself instantaneously from one extremity of the system to the other. In whatever manner this operation is conducted, whether by the vibrations, as it were, of elastic cords or by a subtle fire, or by a matter resembling electricity, which not only resides in animal as in all other bodies, but is being continually renewed in them by the movements of the heart and lungs, by the friction of the blood within the arteries, and also by the action of exterior causes upon our organs of sense--in whatever manner, I say, the operation is conducted, it is nevertheless certain that the nerves and membranes are the only parts in an animal body that can feel. The blood, lymphs, and all other fluids, the fats, bone, flesh, and all other solids, are of themselves void of sensation. And so also is the brain; it is a soft and inelastic substance, incapable therefore of producing or of propagating the movement, vibrations, or concussions which, result in perception. The meninges, on the other hand, are exceedingly sensitive, and are the envelopes of all the nerves; like the nerves, they take rise in the head; and, dividing themselves like the branches of the nerves, they extend even to their smallest ramifications: they are, so to speak, flattened nerves; they are of the same substance as the nerves, are nearly of the same degree of elasticity, and form a necessary part of the system of sensation. If, then, the seat of the sensations must be placed in the head, let it be placed in the meninges, and not in the medullary part of the brain, which is of an entirely different substance."[95] If this is so, it appears from what will follow as though the meninges must be the "stock" rather than the diaphragm. "What perhaps has given rise to the opinion that the seat of all sensations and the centre of all sensibility is in the brain, is the fact that the nerves, which are the organs of perception, all attach themselves to the brain, which has hence come to be regarded as the one common centre which can receive all their vibrations and impressions. This fact alone has sufficed to indicate the brain as the origin of perceptions--as the essential organ of sensations; in a word, as the common sensorium. This supposition has appeared so simple and natural that its physical impossibility has been overlooked, an impossibility, however, which should be sufficiently apparent. For how can a part which cannot feel--a soft inactive substance like the brain--be the very organ of perception and movement? How can this soft and perceptionless part not only receive impressions, but preserve them for a length of time, and transmit their undulatory movements (_en propage les ébranlements_) throughout all the solid and feeling parts of the body? It may perhaps be maintained with Descartes and M. de Peyronie that the principle of sensation does not reside in the brain, but in the pineal gland or in the _corpus callosum_; but a glance at the conformation of the brain itself will suffice to show that these parts do not join on to the nerves, but that they are entirely surrounded by those parts of the brain which do not feel, and are so separated from the nerves that they cannot receive any movement from them; whence it follows that this second supposition is as groundless as the first."[96] What, then, asks Buffon, _is_ the use of the brain? Man, the quadrupeds, and birds all have larger brains, and at the same time more extended perceptions, than fishes, insects, and those other living beings whose brains are smaller in proportion. "When the brain is compressed, there is suspension of all power of movement. If this part is not the source of our powers of motion, why is it so necessary and so essential? Why, again, does it seem so proportionate in each animal to the amount of perceiving power which that animal possesses? "I think I can answer this question in a satisfactory manner, difficult though it seems; but in order that I may do so, I would ask the reader to lend me his attention for a few moments while we regard the brain simply _as brain_, and have no other idea concerning it than we can derive from inspection and reflection. The brain, as well as the _medulla oblongata_ and the spinal marrow, which are but prolongations of the brain itself, is only a kind of hardly organized mucilage; we find in it nothing but the extremities of small arteries, which run into it in very great numbers, but which convey a white and nourishing lymph instead of blood. When the parts of the brain are disunited by maceration, these same small arteries, or lymphatic vessels, appear as very delicate threads throughout their whole length. The nerves, on the contrary, do not penetrate the substance of the brain; they abut upon its surface only; before reaching it they lose their elasticity and solidity, and the extremities of the nerves which are nearest to the brain are soft, and nearly mucilaginous. From this exposition, in which there is nothing hypothetical, it appears that the brain, which is nourished by the lymphatic arteries, does in its turn provide nourishment for the nerves, and that we must regard these as a kind of vegetation which rises as trunks and branches from the brain, and become subsequently subdivided into an infinite number, as it were, of twigs. The brain is to the nerves what the earth is to plants: the last extremities of the nerves are the roots, which with every vegetable are more soft and tender than the trunk or branches; they contain a ductile matter fit for the growth and nourishment of the nervous tree or fibre; they draw the ductile matter from the substance of the brain itself, to which the arteries are continually bringing the lymph that is necessary to supply it. The brain, then, instead of being the seat of the sensations, and the originator of perception, is an organ of secretion and nutrition only, though a very essential organ, without which the nerves could neither grow nor be maintained. "This organ is greater in man, in quadrupeds, and in birds, because the number or bulk of the nerves is greater in these animals than in fishes or insects, whose power of perception is more feeble, for this very reason, that they have but a small brain; one, in fact, that is proportioned to the small quantity of nerves which that brain must support. Nor can I omit to state here that man has not, as has been pretended by some, a larger brain than has any other animal; for there are apes and cetacea which have more brain than man in proportion to the volume of their bodies--another fact which proves that the brain is neither the seat of sensations nor the originator of perception, since in that case these animals would have more sensations and perception than man. "If we consider the manner in which plants derive their nourishment, we shall find that they do not draw up the grosser parts either of earth or water; these parts must be reduced by warmth into subtle vapours before the roots can suck them up into the plant. In like manner the nutrition of the nerves is only effected by means of the more subtle parts of the humidity of the brain, which are sucked up by the roots or extremities of the nerves, and are carried thence through all the branches of the sensory system. This system forms, as we have said, a whole, all whose parts are interconnected by so close a union that we cannot wound one without communicating a violent shock to all the others; the wounding or simply pulling of the smallest nerve is sufficient to cause lively irritation to all the others, and to put the body in convulsion; nor can we ease this pain and convulsion except by cutting the nerve higher up than the injured part; but on this all the parts abutting on this nerve become thenceforward senseless and immovable for ever. The brain should not be considered as of the same character, nor as an organic portion of the nervous system, for it has not the same properties nor the same substance, being neither solid nor elastic, nor yet capable of feeling. I admit that on its compression perception ceases, but this very fact shows it to be a body foreign to the nervous system itself, which, acting by its weight, or pressure, against the extremities of the nerves, oppresses them and stupefies them in the same way as a weight placed upon the arm, leg, or any other part of the body, stupefies the nerves and deadens the perceptions of that part. And it is evident that this cessation of sensation on compression is but a suspension and temporary stupefaction, for the moment the compression of the brain ceases, perception and the power of movement returns. Again, I admit that on tearing the medullary substance, and on wounding the brain till the _corpus callosum_ is reached, convulsion, loss of sensation, and death ensue; but this is because the nerves are so entirely deranged that they are, so to speak, torn up by the roots and wounded all together, and at their source. "In further proof that the brain is neither the centre of perception nor the seat of the sensations, I may remind the reader that animals and even children have been born without heads and brains, and have yet had feeling, movement, and life. There are also whole classes of animals, like insects and worms, with a brain that is by no means a distinct mass nor of sensible volume, but with only something which corresponds with the _medulla oblongata_ and the spinal marrow. There would be more reason, then, in placing the seat of the feelings and perceptions in the spinal marrow, which no animal is without, than in the brain which is not an organ common to all creatures that can feel." If Buffon's ideas concerning the brain are as just as they appear to be, the resemblance between plants and animals is more close than is apparent, even to a superficial observer, on a first inspection of the phenomena. Such an observer, however, on looking but a little more intently, will see the higher _vertebrata_ as perambulating vegetables planted upside down. So the man who had been born blind, on being made to see, and on looking at the objects before him with unsophisticated eyes, said without hesitation that he saw "men as trees walking," thus seeing with more prophetic insight than either he or the bystanders could interpret. For our skull is as a kind of flower-pot, and holds the soil from which we spring, that is to say the brain; our mouth and stomach are roots, in two stories or stages; our bones are the trellis-work to which we cling while going about in search of sustenance for our roots; or they are as the woody trunk of a tree; _we_ are the nerves which are rooted in the brain, and which draw thence the sustenance which is supplied it by the stomach; our lungs are leaves which are folded up within us, as the blossom of a fig is hidden within the fruit itself. This is what should follow if Buffon's theory of the brain is allowed to stand, which I hope will prove to be the case, for it is the only comfortable thought concerning the brain that I have met with in any writer. I have given it here at some length on account of its importance, and for the illustration it affords of Buffon's hatred of mystery, rather than for its bearing upon evolution. The fact that our leading men of science have adopted other theories will weigh little with those who have watched scientific orthodoxy with any closeness. What Buffon thought of that orthodoxy may be gathered from the following:-- "The greatest obstacles to the advancement of human knowledge lie less in things themselves than in man's manner of considering them. However complicated a machine the human body may be, it is still less complicated than are our own ideas concerning it. It is less difficult to see Nature as she is, than as she is presented to us. She carries a veil only, while we would put a mask over her face; we load her with our own prejudices, and suppose her to act and to conduct her operations even after the same fashion as ourselves.[97] . . . . . . "I am by no means speaking of those purely arbitrary systems which we are able at a glance to detect as chimeras that are being pretended to us as realities, but I refer to the methods whereby people have set themselves seriously to study nature. Even the experimental method itself has been more fertile of error than of truth, for though it is indeed the surest, yet is it no surer than the hand of him who uses it. No matter how little we incline out of the straight path, we soon find ourselves wandering in a sterile wilderness, where we can see but a few obscure objects scattered sparsely; nevertheless we do violence to these facts and to ourselves, and resemble them together on a conceit of analogies and common properties amongst them. Then, passing and repassing complaisantly over the tortuous path which we have ourselves beaten, we deem the road a worn one, and though it leads no whither, the world follows it, adopts it, and accepts its supposed consequences as first principles. I could show this by laying bare the origin of that which goes by the name of 'principle' in all the sciences, whether abstract or natural. In the case of the former, the basis of principle is abstraction--that is to say, one or more suppositions: in that of the second, principles are but the consequences, better or worse, of the methods which may have been followed. And to speak here of anatomy only, did not he who first surmounted his natural repugnance and set himself to work to open a human body--did he not believe that through going all over it, dissecting it, dividing it into all its parts, he would soon learn its structure, mechanism, and functions? But he found the task greater than he had expected, and renouncing such pretensions, was fain to content himself with a method--not for seeing and judging, but for seeing after an orderly fashion. This method ... is still the sole business of our ablest anatomists, but it is not science. It is the road which should lead scienceward, and might perhaps have reached science itself, if instead of walking ever on a single narrow path men had set the anatomy of man and that of animals face to face with one another. For, what real knowledge can be drawn from an isolated pursuit? Is not the foundation of all science seen to consist in the comparison which the human mind can draw between different objects in the matter of their resemblances and differences--of their analogous or conflicting properties, and of all the relations in which they stand to one another? The absolute, if it exist at all, is but of the concurrence of man's own knowledge; we judge and can judge of things only by their bearings one upon another; hence whenever a method limits us to only a single subject, whenever we consider it in its solitude and without regard to its resemblances or to its differences from other objects, we can attain to no real knowledge, nor yet, much less, reach any general principle. We do but give names, and make descriptions of a thing, and of all its parts. Hence comes it that, after three thousand years of dissection, anatomy is still but a nomenclature, and has hardly advanced a step towards its true object, which is the science of animal economy. Furthermore, what defects are there not in the method itself, which should above all things else be simple and easy to be understood, depending as it does upon inspection and having denominations only for its end! For seeing that nomenclature has been mistaken for knowledge, men have made it their chief business to multiply names, instead of limiting things; they have crushed themselves under the burden of details, and been on the look out for differences where there was no distinction. When they had given a new name they conceived of it as a new thing, and described the smallest parts with the most minutious exactness, while the description of some still smaller part, forgotten or neglected by previous anatomists, has been straightway hailed as a discovery. The denominations themselves being often taken from things which had no relation to the object that it was desired to denominate, have served but to confound confusion. The part of the brain, for example, which is called testes and nates, wherein does it so differ from the rest of the brain that it should deserve a name? These names, taken at haphazard or springing from some preconceived opinion, have themselves become the parents of new prejudices and speculations; other names given to parts which have been ill observed, or which are even non-existent, have been sources of new errors. What functions and uses has it not been attempted to foist upon the pineal gland, and on the alleged empty space in the brain which is called the arch, the first of which is but a gland, while the very existence of the other is doubtful,--the empty space being perhaps produced by the hand of the anatomist and the method of dissection."[98] _The Genus felis._ In his preliminary remarks upon the lion, Buffon while still professing to believe in some considerable mutability of species, seems very far from admitting that all living forms are capable of modification. But he has shown us long since how clearly he saw the impossibility of limiting mutability, if he once admitted so much of the thin end of the wedge as that a horse and an ass might be related. It is plain, therefore, that he is not speaking "_au réel_" here, and we accordingly find him talking clap-trap about the nobleness of the lion in having no species immediately allied to it. A few lines lower on he reminds us in a casual way that the ass and horse are related. He writes:-- "Added to all these noble individual features the lion has also what may be called a _specific_ nobility. For I call those species noble which are constant, invariable, and which are above suspicion of having degenerated. These species are commonly isolated, and the only ones of their genus. They are distinguished by such well-marked features that they cannot be mistaken, nor confounded with any other species. To begin for example with man, the noblest of created beings; he is but of a single species, inasmuch as men and women will breed freely _inter se_ in spite of all existing differences of race, climate and colour; and also inasmuch as there is no other animal which can claim either a distant or near relationship with him. The horse, on the other hand, is more noble as an individual than as a species, for he has the ass as his near neighbour, _and seems himself to be nearly enough related to it_; ... the dog is perhaps of even less noble species, approaching as he does to the wolf, fox, and jackal, _which we can only consider to be the degenerated species of a single family_"[99]--all which may seem very natural opinions for a French aristocrat in the days before the Revolution, but which cannot for a moment be believed to have been Buffon's own. I have not ascertained the date of Buffon's little quarrel with the Sorbonne, but I cannot doubt that if we knew the inner history of the work we are considering, we should find this passage and others like it explained by the necessity of quieting orthodox adversaries. He concludes the paragraph from which I have just been quoting by saying, "To class man and the ape together, or the lion with the cat, and to say that the lion is a _cat with a mane and a long tail_--this were to degrade and disfigure nature instead of describing her and denominating her species." Buffon very rarely uses italics, but those last given are his, not mine; could words be better chosen to make us see the lion and the cat as members of the same genus? No wonder the Sorbonne considered him an infelicitous writer; why could he not have said "cat," and have done with it, instead of giving a couple of sly but telling touches, which make the cat as like a lion as possible, and then telling us that we must not call her one? Sorbonnes never do like people who write in this way. "The lion, then, belongs to a most noble species, standing as he does alone, and incapable of being confounded with the tiger, leopard, ounce, &c., while, on the contrary, those species, which appear to be least distant from the lion, are very sufficiently indistinguishable, so that travellers and nomenclators are continually confounding them."[100] If this is not pure malice, never was a writer more persistently unfortunate in little ways. Why remind us here that the species which come nearest to the lion are so hard to distinguish? Why not have said nothing about it? As it is, the case stands thus: we are required to admit close resemblance between the leopard and the tiger, while we are to deny it between the tiger and the lion, in spite of there being no greater outward difference between the first than between the second pair, and in spite of the hurried whisper "_cat with a mane and a long tail_" still haunting our ears. Isidore Geoffroy and his followers may consent to this arrangement, but I hope the majority of my readers will not do so. I went on to the account of the tiger with some interest to see the line which Buffon would take concerning it. I anticipated that we should find cats, pumas, lynxes, &c., to be really very like tigers, and was surprised to learn that the "true" tiger, though certainly not unlike these animals, was still to be distinguished from "many others which had since been called tigers." He is on no account to be confounded with these, in spite of the obvious temptation to confound him. He is "a rare animal, little known to the ancients, and badly described by the moderns." He is a beast "of great ferocity, of terrible swiftness, and surpassing even the proportions of the lion." The effect of the description is that we no longer find the lion standing alone, but with the tiger on a par with him if not above him; but at the same time we fall easy victims to the temptation to confound the tiger with "the many other animals which are also called tigers." A surface stream has swept the members of the cat family in different directions, but a stealthy undercurrent has seized them from beneath, and they are now happily reunited. _Animals of the Old and New World--Changed Geographical Distribution._ Writing upon the animals of the old world,[101] and referring to the humps of the camel and the bison, Buffon shows that very considerable modification may be effected in some animals within even a few generations, but he attributes the effect produced to the direct influence of climate. Buffon concludes his sketch of the animals of the new world by pointing out that the larger animals of the African torrid zone have been hindered by sea and desert from finding their way to America, and by claiming to be the first "even to have suspected" that there was not a single denizen of the torrid zone of one continent which was common also to the other.[102] The animals common to both continents are those which can stand the cold and which are generally suited for a temperate climate. These, Buffon believes, to have travelled either over some land still unknown, or "more probably," over territory which has long since been submerged. The species of the old and new world are never without some well-marked difference, which however should not be held sufficient for us to refuse to admit their practical identity. But he maintains, I imagine wilfully, that there is a tendency in all the mammalia to become smaller on being transported to the new world, and refers the fact to the quality of the earth, the condition of the climate, the degrees of heat and humidity, to the height of mountains, amounts of running or stagnant waters, extent of forest, and above all to the brutal condition of nature in a new country, which he evidently regards with true aristocratic abhorrence.[103] Then follows a passage which I had better perhaps give in full:-- The mammoth "was certainly the greatest and strongest of all quadrupeds; but it has disappeared; and if so, how many smaller, feebler, and less remarkable species must have also perished without leaving us any traces or even hints of their having existed? How many other species have changed their nature, that is to say, become perfected or degraded, through great changes in the distribution of land and ocean, through the cultivation or neglect of the country which they inhabit, through the long-continued effects of climatic changes, so that they are no longer the same animals that they once were? Yet of all living beings after man, the quadrupeds are the ones whose nature is most fixed and form most constant: birds and fishes vary much more easily; insects still more again than these, and if we descend to plants, which certainly cannot be excluded from animated nature, we shall be surprised at the readiness with which species are seen to vary, and at the ease with which they change their forms and adopt new natures. "It is probable then that all the animals of the new world are derived from congeners in the old, without any deviation from the ordinary course of nature. We may believe that having become separated in the lapse of ages, by vast oceans and countries which they could not traverse, they have gradually been affected by, and derived impressions from, a climate which has itself been modified so as to become a new one through the operation of those same causes which dissociated the individuals of the old and new world from one another; thus in the course of time they have grown smaller and changed their characters. This, however, should not prevent our classifying them as different species now, for the difference is no less real whether it is caused by time, climate and soil, or whether it dates from the creation. _Nature I maintain is in a state of continual flux and movement. It is enough for man if he can grasp her as she is in his own time, and throw but a glance or two upon the past and future, so as to try and perceive what she may have been in former times and what one day she may attain to._"[104] _The Buffalo--Animals under Domestication._ "The bison and the aurochs," says Buffon, "differ only in unessential characteristics, and are, by consequence, of the same species as our domestic cattle, so that I believe all the pretended species of the ox, whether ancient or modern, may be reduced to three--the bull, the buffalo, and the bubalus. "The case of animals under domestication is in many respects different from that of wild ones; they vary much more in disposition, size and shape, especially as regards the exterior parts of their bodies: the effects of climate, so powerful throughout nature, act with far greater effect upon captive animals than upon wild ones. Food prepared by man, and often ill chosen, combined with the inclemency of an uncongenial climate--these eventuate in modifications sufficiently profound to become constant and hereditary in successive generations. I do not pretend to say that this general cause of modification is so powerful as to change radically the nature of beings which have had their impress stamped upon them in that surest of moulds--heredity; but it nevertheless changes them in not a few respects; it masks and transforms their outward appearance; it suppresses some of their parts, and gives them new ones; it paints them with various colours, and _by its action on bodily habits influences also their natures, instincts, and most inward qualities_" (and what is this but "radically changing their nature"?). "The modification of but a single part, moreover, in a whole as perfect as an animal body, will necessitate a correlative modification in every other part, and it is from this cause that our domestic animals differ almost as much in nature and instinct, as in form, from those from which they originally sprung."[105] Buffon confirms this last assertion by quoting the sheep as an example--an animal which can now no longer exist in a wild state. Then returning to cattle, he repeats that many varieties have been formed by the effects--"diverse in themselves, and diverse in their combinations--of climate, food, and treatment, whether under domestication or in their wild state." These are the main causes of variation ("causes générales de variété"),[106] among our domesticated animals, but by far the greatest is changed climate in consequence of their accompanying man in his migrations. The effects of the foregoing causes of modification, especially the last of them, are repeatedly insisted on in the course of the forty pages which complete the preliminary account of the buffalo. What holds good for the buffalo does so also for the mouflon or wild sheep. This, Buffon declares to be the source of all our domesticated breeds: of these there are in all some four or five, "all of them being but degenerations from a single stock, produced by man's agency, and propagated for his convenience."[107] At the same time that man has protected them he has hunted out the original race which was "less useful to him,"[108] so that it is now to be found only in a few secluded spots, such as the mountains of Greece, Cyprus, and Sardinia. Buffon does not consider even the differences between sheep and goats to be sufficiently characteristic to warrant their being classed as different species. "I shall never tire," he continues, "of repeating--seeing how important the matter is--that we must not form our opinions concerning nature, nor differentiate (différencier) her species, by a reference to minor special characteristics. And, again, that systems, far from having illustrated the history of animals, have, on the contrary, served rather to obscure it ... leading, as they do, to the creation of arbitrary species which nature knows nothing about; perpetually confounding real and hypothetical existences; giving us false ideas as to the very essence of species; uniting them and separating them without foundation or knowledge, and often without our having seen the animal with which we are dealing."[109] _First and Second Views of Nature._ The twelfth volume begins with a preface, entitled "A First View of Nature," from which I take the following:-- "What cannot Nature effect with such means at her disposal? She can do all except either create matter or destroy it. These two extremes of power the deity has reserved for himself only; creation and destruction are the attributes of his omnipotence. To alter and undo, to develop and to renew--these are powers which he has handed over to the charge of Nature."[110] The thirteenth volume opens with a second view of nature. After describing what a man would have observed if he could have lived during many continuous ages, Buffon goes on to say:-- "And as the number, sustenance, and balance of power among species is constant, Nature would present ever the same appearance, and would be in all times and under all climates absolutely and relatively the same, if it were not her fashion to vary her individual forms as much as possible. The type of each species is founded in a mould of which the principal features have been cut in characters that are ineffaceable and eternally permanent, but all the accessory touches vary; no one individual is the exact facsimile of any other, and no species exists without a large number of varieties. In the human race on which the divine seal has been set most firmly, there are yet varieties of black and white, large and small races, the Patagonian, Hottentot, European, American, Negro, which, though all descended from a common father, nevertheless exhibit no very brotherly resemblance to one another."[111] On an earlier page there is a passage which I may quote as showing Buffon to have not been without some--though very imperfect--perception of the fact which evidently made so deep an impression upon his successor, Dr. Erasmus Darwin. I refer to that continuity of life in successive generations, and that oneness of personality between parents and offspring, which is the only key that will make the phenomena of heredity intelligible. "Man," he says, "and especially educated man, is no longer a single individual, but represents no small part of the human race in its entirety. He was the first to receive from his fathers the knowledge which their own ancestors had handed down to them. These, having discovered the divine art of fixing their thoughts so that they can transmit them to their posterity, become, as it were, one and the same people with their descendants (_se sont, pour ainsi dire, identifiés avec leur neveux_); while our descendants will in their turn be one and the same people with ourselves (_s'identifieront avec nous_). This reunion in a single person of the experience of many ages, throws back the boundaries of man's existence to the utmost limits of the past; he is no longer a single individual, limited as other beings are to the sensations and experiences of to-day. In place of the individual we have to deal, as it were, with the whole species."[112] "Differences in exterior are nothing in comparison with those in interior parts. These last must be regarded as the causes, while the others are but the effects. The interior parts of living beings are the foundation of the plan of their design; this is their essential form, their real shape, their exterior is only the surface, or rather the drapery in which their true figure is enveloped. How often does not the study of comparative anatomy show us that two exteriors which differ widely conceal interiors absolutely like each other, and, on the contrary, that the smallest internal difference is accompanied by the most marked differences of outward appearance, changing as it does even the natural habits, faculties and attributes of the animal?"[113] _Apes and Monkeys._ The fourteenth volume is devoted to apes and monkeys, and to the chapter with which the volumes on quadrupeds are brought to a conclusion--a chapter for which perhaps the most important position in the whole work is thus assigned. It is very long, and is headed "On Descent with Modification" ("De la Dégénération des Animaux"). This is the chapter in which Buffon enters more fully into the "causes or means" of the transformation of species. At the opening of the chapter on the nomenclature of monkeys, the theory is broached that there is a certain fixed amount of life-substance as of matter in nature; and that neither can be either augmented or diminished. Buffon maintains this organic and living substance to be as real and durable as inanimate matter; as permanent in its state of life as the other in that of death; it is spread over the whole of nature, and passes from vegetables to animals by way of nutrition, and from animals back to vegetables through putrefaction, thus circulating incessantly to the animation of all that lives. As might be expected, Buffon is loud in his protest against any real similarity between man and the apes--man has had the spirit of the Deity breathed into his nostrils, and the lowest creature with this is higher than the highest without it. Having settled this point, he makes it his business to show how little difference in other respects there is between the apes and man. "One who could view," he writes, "Nature in her entirety, from first to last, and then reflect upon the manner in which these two substances--the living and the inanimate--act and react upon one another, would see that every living being is a mould which casts into its own shape those substances upon which it feeds; that it is this assimilation which constitutes the growth of the body, whose development is not simply an augmentation of volume, but an extension in all its dimensions, a penetration of new matter into all parts of its mass: he would see that these parts augment proportionately with the whole, and the whole proportionately with these parts, while general configuration remains the same until the full development is accomplished.... He would see that man, the quadruped, the cetacean, the bird, reptile, insect, tree, plant, herb, all are nourished, grow, and reproduce themselves on this same system, and that though their manner of feeding and of reproducing themselves may appear so different, this is only because the general and common cause upon which these operations depend can only operate in the individual agreeably with the form of each species. Travelling onward (for it has taken the human mind ages to arrive at these great truths, from which all others are derived), he would compare living forms, give them names to distinguish them, and other names to connect them with each other. Taking his own body as the model with which all living forms should be compared, and having measured them, explained them thoroughly, and compared them in all their parts, he would see that there is but small difference between the forms of living beings; that by dissecting the ape he could arrive at the anatomy of man, and that taking some other animal we find always the same ultimate plan of organization, the same senses, the same viscera, the same bones, the same flesh, the same movements of the fluids, the same play and action of the solids; he would find all of them with a heart, veins, arteries, in all the same organs of circulation, respiration, digestion, nutrition, secretion; in all of them a solid frame, composed of pieces put together in nearly the same manner; and he would find this system always the same, from man to the ape, from the ape to the quadrupeds, from the quadrupeds to the cetacea, birds, fishes, reptiles; this system or plan then, I say, if firmly laid hold of and comprehended by the human mind, is a true copy of nature; it is the simplest and most general point of view from which we can consider her, and if we extend our view, and go on from what lives to what vegetates, we may see this plan--which originally did but vary almost imperceptibly--change its scope and descend gradually from reptiles to insects, from insects to worms, from worms to zoophytes, from zoophytes to plants, and yet keeping ever the same fundamental unity in spite of differences of detail, insomuch that nutrition, development, and reproduction remain the common traits of all organic bodies; traits eternally essential and divinely implanted; which time, far from effacing or destroying, does but make plainer and plainer continually." This is the writer who can see nothing in common between the horse and the zebra except that each has a solid hoof.[114] He continues:-- "If from this grand tableau of resemblances, in which the living universe presents itself to our eyes as though it were a single family, we pass to a tableau rather of the differences between living forms, we shall see that, with the exception of some of the greater species, such as the elephant, rhinoceros, hippopotamus, tiger, lion, which must each have their separate place, the other races seem all to blend with neighbouring forms, and to fall into groups of likenesses, greater or lesser, and of genera which our nomenclators represent to us by a network of shapes, of which some are held together by the feet, others by the teeth, horns, and skin, and others by points of still minor importance. And even those whose form strikes us as most perfect, as approaching most nearly to our own--even the apes--require some attention before they can be distinguished from one another, for the privilege of being an isolated species has been assigned less to form than to size; and man himself, though of a separate species and differing infinitely from all or any others, has but a medium size, and is less isolated and has nearer neighbours than have the greater animals. If we study the Orang-outang with regard only to his configuration, we might regard him, with equal justice, as either the highest of the apes or as the lowest of mankind, because, with the exception of the soul, he wants nothing of what we have ourselves, and because, as regards his body, he differs less from man than he does from other animals which are still called apes."[115] The want of a soul Buffon maintains to be the only essential difference between the Orang-outang and man--"his body, limbs, senses, brain and tongue are the same as ours. He can execute whatever movements man can execute; yet he can neither think nor speak, nor do any action of a distinctly human character. Is this merely through want of training? or may it not be through wrong comparison on our own parts? We compare the wild ape in the woods to the civilized citizen of our great towns. No wonder the ape shows to disadvantage. He should be compared with the hideous Hottentot rather, who is himself almost as much above the lowest man, as the lowest man is above the Orang-outang."[116] The passage is a much stronger one than I have thought it fit to quote. The reader can refer to it for himself. After reading it I entertain no further doubt that Buffon intended to convey the impression that men and apes are descended from common ancestors. He was not, however, going to avow this conclusion openly. "I admit," he continues, "that if we go by mere structure the ape might be taken for a variety of the human race; the Creator did not choose to model mankind upon an entirely distinct system from the other animals: He comprised their form and man's under a plan which is in the main uniform."[117] Buffon then dwells upon the possession of a soul by man; "even the lowest creature," he avers, "which had this, would have become man's rival." "The ape then is purely an animal, far from being a variety of our own species, he does not even come first in the order of animals, since he is not the most intelligent: the high opinion which men have of the intelligence of apes is a prejudice based only upon the resemblance between their outward appearance and our own."[118] But the undiscerning were not only to be kept quiet, they were to be made happy. With this end, if I am not much mistaken, Buffon brings his chapter on the nomenclature of apes to the following conclusion:-- "The ape, which the philosopher and the uneducated have alike regarded as difficult to define, and as being at best equivocal, and midway between man and the lower animals, proves in fact to be an animal and nothing more; he is masked externally in the shape of man, but internally he is found incapable of thought, and of all that constitutes man; apes are below several of the other animals in respect of qualities corresponding to their own, and differ essentially from man, in nature, temperament, the time which must be spent upon their gestation and education, in their period of growth, duration of life, and in fact in all those profounder habits which constitute what is called the 'nature' of any individual existence."[119] This is handsome, and leaves the more timorous reader in full possession of the field. Buffon is accordingly at liberty in the following chapter to bring together every fact he can lay his hands on which may point the resemblance between man and the Orang-outang most strongly; but he is careful to use inverted commas here much more freely than is his wont. Having thus made out a strong case for the near affinity between man and the Orang-outang, and having thrown the responsibility on the original authors of the passages he quotes, he excuses himself for having quoted them on the ground that "everything may seem important in the history of a brute which resembles man so nearly," and then insists upon the points of difference between the Orang-outang and ourselves. They do not, however, in Buffon's hands come to much, until the end of the chapter, when, after a _résumé_ dwelling on the points of resemblance, the differences are again emphatically declared to have the best of it. I need not follow Buffon through his description of the remaining monkeys. It comprises 250 pp., and is confined to details with which we have no concern; but the last chapter--"De la Dégénération des Animaux"--deserves much fuller quotation than my space will allow me to make from it. The chapter is very long, comprising, as I have said, over sixty quarto pages. It is impossible, therefore, for me to give more than an outline of its contents. _Causes or Means of the Transformation of Species._ The human race is declared to be the one most capable of modification, all its different varieties being descended from a common stock, and owing their more superficial differences to changes of climate, while their profounder ones, such as woolly hair, flat noses, and thick lips, are due to differences of diet, which again will vary with the nature of the country inhabited by any race. Changes will be exceedingly gradual; it will take centuries of unbroken habit to bring about modifications which can be transmitted with certainty so as to eventuate in national characteristics.[120] It is a pleasure to find that here, too, habit is assigned as the main cause which underlies heredity. Modification will be much prompter with animals. When compelled to abandon their native land, they undergo such rapid and profound modification, that at first sight they can hardly be recognized as the same race, and cannot be detected in their disguise till after the most careful inspection, and on grounds of analogy only. Domestication will produce still more surprising results; the stigmata of their captivity, the marks of their chains, can be seen upon all those animals which man has enslaved; the older and more confirmed the servitude, the deeper will be its scars, until at length it will be found impossible to rehabilitate the creature and restore to it its lost attributes. "Temperature of climate, quality of food, and the ills of slavery--here are the three main causes of the alteration and degeneration of animals. The consequences of each of these should be particularly considered, so that by examining Nature as she is to-day we may thus perceive what she was in her original condition."[121] I have more than once admitted that there is a wide difference between this opinion, which assigns modification to the direct influence of climate, food, and other changed conditions of life, and that of Dr. Erasmus Darwin, which assigns only an indirect effect to these, while the direct effect is given to changed actions in consequence of changed desires; but it is surprising how nearly Buffon has approached the later and truer theory, which may perhaps have been suggested to Dr. Darwin by the following pregnant passage--as pregnant, probably, to Buffon himself as to another:-- "The camel is the animal which seems to me to have felt the weight of slavery most profoundly. He is born with wens upon his back and callosities upon his knees and chest; these callosities are the unmistakable results of rubbing, for they are full of pus and of corrupted blood. The camel never walks without carrying a heavy burden, and the pressure of this has hindered, for generations, the free extension and uniform growth of the muscular parts of the back; whenever he reposes or sleeps his driver compels him to do so upon his folded legs, so that little by little this position becomes habitual with him. All the weight of his body bears, during several hours of the day continuously, upon his chest and knees, so that the skin of these parts, pressed and rubbed against the earth, loses its hair, becomes bruised, hardened, and disorganized. "The llama, which like the camel passes its life beneath burdens, and also reposes only by resting its weight upon its chest, has similar callosities, which again are perpetuated in successive generations. Baboons, and pouched monkeys, whose ordinary position is a sitting one, whether waking or sleeping, have callosities under the region of the haunches, and this hard skin has even become inseparable from the bone against which it is being continually pressed by the weight of the body; in the case, however, of these animals the callosities are dry and healthy, for they do not come from the constraint of trammels, nor from the burden of a foreign weight, but are the effects only of the natural habits of the animal, which cause it to continue longer seated than in any other position. There are callosities of these pouched monkeys which resemble the double sole of skin which we have ourselves under our feet; this sole is a natural hardness which our continued habit of walking or standing upright will make thicker or thinner according to the greater or less degree of friction to which we subject our feet."[122] This involves the whole theory of Dr. Darwin. Wild animals would not change either their food or climate if left to themselves, and in this case they would not vary, but either man or some other enemies have harassed most of them into migrations; "those whose nature was sufficiently flexible to lend itself to the new situation spread far and wide, while others have had no resource but the deserts in the neighbourhood of their own countries."[123] Since food and climate, and still less man's empire over them, can have but little effect upon wild animals, Buffon refers their principal varieties in great measure to their sexual habits, variations being much less frequent among animals that pair and breed slowly, than among those which do not mate and breed more freely. After running rapidly over several animals, and discussing the flexibility or inflexibility of their organizations, he declares the elephant to be the only one on which a state of domestication has produced no effect, inasmuch as "it refuses to breed under confinement, and cannot therefore transmit the badges of its servitude to its descendants."[124] Here is an example of Buffon's covert manner, in the way he maintains that descent with modification may account not only for specific but for generic differences. "But after having taken a rapid survey of the varieties which indicate to us the alterations that each species has undergone, there arises a broader and more important question, how far, namely, species themselves can change--how far there has been an older degeneration, immemorial from all antiquity, which has taken place in every family, or, if the term is preferred, _in all the genera_ under which those species are comprehended which neighbour one another without presenting points of any very profound dissimilarity? We have only a few isolated species, such as man, which form at once the species and the whole genus; the elephant, the rhinoceros, the hippopotamus, and the giraffe form genera, or simple species, which go down in a single line, with no collateral branches. All other races appear to form families, in which we may perceive a common source or stock from which the different branches seem to have sprung in greater or less numbers according as the individuals of each species are smaller and more fecund."[125] I can see no explanation of the introduction of this passage unless that it is intended to raise the question whether modification may be not only specific but generic, the point of the paragraph lying in the words "dans chaque famille, _ou si l'on veut, dans chacun des genres_." We are told in the next paragraph, that if we choose to look at the matter in this light, well--in that case--we ought to see not only the ass and the horse, but _the zebra too_, as members of the same family; "the number of their points of resemblance being infinitely greater than those in respect of which they differ."[126] Thus, at the close of his work on the quadrupeds, he thinks it well, as at the commencement seventeen years earlier, to emphasize--in his own quiet way--his perception that the principles on which he has been insisting should be carried much farther than he has chosen to carry them. His conclusion is, that "after comparing all the animals and bringing them each under their proper genus, we shall find the two hundred species we have already described to be reducible into a sufficiently small number of families or main stocks from which it is not impossible that all the others may be derived."[127] The chapter closes thus:-- "To account for the origin of these animals" (certain of those peculiar to America), "we must go back to the time when the two continents were not yet separated, and call to mind the earliest geological changes. At the same time, we must consider the two hundred existing species of quadrupeds as reduced to thirty-eight families. And though this is not at all the state of Nature as she is in our time, and as she has been represented in this volume, and though, in fact, it is a condition which we can only arrive at by induction, and by analogies almost as difficult to lay hold of as is the time which has effaced the greater number of their traces, I shall, nevertheless, endeavour to ascend to these first ages of Nature by the aid of facts and monuments which yet remain to us, and to represent the epochs which these facts seem to indicate."[128] The fifteenth volume contains a description of a few more monkeys, as also of some animals which Buffon had never actually seen, a great part being devoted to indices. _Supplement._ The first four volumes of the Supplement to Buffon's 'Natural History,' 1774-1789, contain little which throws additional light upon his opinions concerning the mutability of species. At the beginning, however, of the fifth volume I find the following:-- "On comparing these ancient records of the first ages of life [fossils] with the productions of to-day, we see with sufficient clearness that the essential form has been preserved without alteration in its principal parts: there has been no change whatever in the general type of each species; the plan of the inner parts has been preserved without variation. However long a time we may imagine for the succession of ages, whatever number of generations we may suppose, the individuals of to-day present to us in each genus the same forms as they did in the earliest ages; and this is more especially true of the greater species, whose characters are more invariable and nature more fixed; for the inferior species have, as we have said, experienced in a perceptible manner all the effects of different causes of degeneration. Only it should be remarked in regard to these greater species, such as the elephant and hippopotamus, that in comparing their fossil remains with the existing forms we find the earlier ones to have been larger. Nature was then in the full vigour of her youth, and the interior heat of the earth gave to her productions all the force and all the extent of which they were capable ... if there have been lost species, that is to say animals which existed once, but no longer do so, these can only have been animals which required a heat greater than that of our present torrid zone."[129] The context proves Buffon to have been thinking of such huge creatures as the megatherium and mastodon, but his words seem to limit the extinction of species to the denizens of a hot climate which had turned colder. It is not at all likely that Buffon meant this, as the passage quoted at p. 146 of this work will suffice to show. The whole paragraph is ironical. I can see nothing to justify the conclusion drawn from this passage by Isidore Geoffroy, that Buffon had modified his opinions, and was inclined to believe in a more limited mutability than he had done a few years earlier. His exoteric position is still identical with what it was in the outset, and his esoteric may be seen from the spirit which is hardly concealed under the following:-- "I shall be told that analogy points towards the belief that our own race has followed the same path, and dates from the same period as other species; that it has spread itself even more widely than they; and that if man's creation has a later date than that of the other animals, nothing shows that he has not been subjected to the same laws of nature, the same alterations, and the same changes as they. We will grant that the human species does not differ essentially from others in the matter of bodily organs, and that, in respect of these, our lot has been much the same as that of other animals."[130] _Plants under Domestication._ "If more modern and even recent examples are required in order to prove man's power over the vegetable kingdom, it is only necessary to compare our vegetables, flowers, and fruits with the same species such as they were a hundred and fifty years ago; this can be done with much ease and certainty by running the eye over the great collection of coloured drawings begun in the time of Gaston of Orleans, and continued to the present day at the Jardin du Roi. We find with surprise that the finest flowers of that date, as the ranunculuses, pinks, tulips, bear's ears, &c., would be rejected now, I do not say by our florists, but by our village gardeners. These flowers, though then already cultivated, were still not far above their wild condition. They had a single row of petals only, long pistils, colours hard and false; they had little velvety texture, variety, or gradation of tints, and, in fact, presented all the characteristics of untamed nature. Of herbs there was a single kind of endive, and two of lettuce--both bad--while we can now reckon more than fifty lettuces and endives, all excellent. We can even name the very recent dates of our best pippins and kernel fruits--all of them differing from those of our forefathers, which they resemble in name only. In most cases things remain while names change; here, on the contrary, it is the names that have been constant while the things have varied.[131] . . . . . . "It is not that every one of these good varieties did not arise from the same wild stock; but how many attempts has not man made on Nature before he succeeded in getting them. How many millions of germs has he not committed to the earth, before she has rewarded him by producing them? It was only by sowing, tending, and bringing to maturity an almost infinite number of plants of the same kind that he was able to recognize some individuals with fruits sweeter and better than others; and this first discovery, which itself involves so much care, would have remained for ever fruitless if he had not made a second, which required as much genius as the first required patience--I mean the art of grafting those precious individuals, which, unfortunately, cannot continue a line as noble as their own, nor themselves propagate their rare and admirable qualities? And this alone proves that these qualities are purely individual, and not specific, for the pips or stones of these excellent fruits bring forth the original wild stock, so that they do not form species essentially different from this. Man, however, by means of grafting, produces what may be called secondary species, which he can propagate at will; for the bud or small branch which he engrafts upon the stock contains within itself the individual quality which cannot be transmitted by seed, but which needs only to be developed in order to bring forth the same fruits as the individual from which it was taken in order to be grafted on to the wild stock. The wild stock imparts none of its bad qualities to the bud, for it did not contribute to the forming thereof, being, as it were, a wet nurse, and no true mother. "In the case of animals, the greater number of those features which appear individual, do not fail to be transmitted to offspring, in the same way as specific characters. It was easier then for man to produce an effect upon the natures of animals than of plants. The different breeds in each animal species are variations that have become constant and hereditary, while vegetable species on the other hand present no variations that can be depended on to be transmitted with certainty. "In the species of the fowl and the pigeon alone, a large number of breeds have been formed quite recently, which are all constant, and in other species we daily improve breeds by crossing them. From time to time we acclimatize and domesticate some foreign and wild species. All these examples of modern times prove that man has but tardily discovered the extent of his own power, and that he is not even yet sufficiently aware of it. It depends entirely upon the exercise of his intelligence; the more, therefore, he observes and cultivates nature the more means he will find of making her subservient to him, and of drawing new riches from her bosom without diminishing the treasures of her inexhaustible fecundity."[132] _Birds._ In the preface to his volumes upon birds, Buffon says that these are not only much more numerous than quadrupeds, but that they also exhibit a far larger number of varieties, and individual variations. "The diversities," he declares, "which arise from the effects of climate and food, of domestication, captivity, transportation, voluntary and compulsory migration--all the causes in fact of alteration and degeneration--unite to throw difficulties in the way of the ornithologist."[133] He points out the infinitely keener vision of birds than that of man and quadrupeds, and connects it with their habits and requirements.[134] He does not appear to consider it as caused by those requirements, though it is quite conceivable that he saw this, but thought he had already said enough. He repeatedly refers to the effects of changed climate and of domestication, but I find nothing in the first volume which modifies the position already taken by him in regard to descent with modification: it is needless, therefore, to repeat the few passages which are to be found bearing at all upon the subject. The chapter on the birds that cannot fly, contains a sentence which seems to be the germ that has been developed, in the hands of Lamarck, into the comparison between nature and a tree. Buffon says that the chain of nature is not a single long chain, but is comparable rather to something woven, "which at certain intervals throws out a branch sideways that unites it with the strands of some other weft."[135] On the following page there is a passage which has been quoted as an example of Buffon's contempt for the men of science of his time. The writer maintains that the most lucid arrangement of birds, would have been to begin with those which most resembled quadrupeds. "The ostrich, which approaches the camel in the shape of its legs, and the porcupine in the quills with which its wings are armed, should have immediately followed the quadrupeds, but philosophy is often obliged to make a show of yielding to popular opinions, and _the tribe of naturalists_ is both numerous and impatient of any disturbance of its methods. It would only, then, have regarded this arrangement as an unreasonable innovation caused by a desire to contradict and to be singular."[136] It is, I believe, held not only by "_le peuple des naturalistes_," but by most sensible persons, that the proposed arrangement would not have been an improvement. I find, however, in the preface to the third volume on birds that M. Gueneau de Montbeillard described all the birds from the ostrich to the quail, so the foregoing passage is perhaps his and not Buffon's. If so, the imitation is fair, but when we reflect upon it we feel uncertain whether it is or is not beneath Buffon's dignity. Here, as often with pictures and music, we cannot criticise justly without taking more into consideration than is actually before us. We feel almost inclined to say that if the passage is by Buffon it is probably right, and if by M. Gueneau de Montbeillard, probably wrong. It must also be remembered that, as we learn from the preface already referred to, Buffon was seized at this point in his work with a long and painful illness, which continued for two years; a single hasty passage in so great a writer may well be pardoned under such circumstances. Looking through the third and remaining volumes on birds, the greater part of which was by Gueneau de Montbeillard, and bearing in mind that in point of date they are synchronous with some of those upon quadrupeds from which I have already extracted as much as my space will allow, and not seeing anything on a rapid survey which promises to throw new light upon the author's opinions, I forbear to quote further. I therefore leave Buffon with the hope that I have seen him more justly than some others have done, but with the certainty that the points I have caught and understood are few in comparison with those that I have missed. FOOTNOTES: [65] 'Hist. Nat.,' tom. i. p. 13, 1749. [66] Ibid. [67] Ibid. p. 16. [68] Tom. i. p. 21. [69] Ibid. p. 23. [70] Tom. ii. p. 9, 1749. [71] Ibid. p. 10. [72] Tom. iv. p. 31, 1753. [73] Tom. iv. p. 55. [74] Tom. iv. p. 98, 1753. [75] Ibid. [76] Tom. viii. p. 283, &c., 1760. [77] Tom. iv. p. 102, 1760. [78] Tom. iv. p. 103, 1753. [79] Dr. Darwin, 'Zoonomia,' vol. i. p. 183, 1796. [80] Ibid. p. 184. [81] Dr. Darwin,'Zoonomia,' vol. i. p. 186. [82] Tom. v. p. 63, 1755. [83] Ibid. p. 64. [84] Tom. v. p. 103, 1755. [85] Tom. v. p. 104, 1755. [86] Tom. v. pp. 192-195, 1755. [87] Tom. v. p. 195. [88] Tom. v. pp. 196, 197. [89] This passage would seem to be the one which has suggested the following to the author of 'The Vestiges of Creation':-- "He [the Deity] has endowed the families which enjoy His bounty with an almost infinite fecundity, ... but the limitation of the results of this fecundity ... is accomplished in a befitting manner by His ordaining that certain other animals shall have endowments sure so to act as to bring the rest of animated beings to a proper balance" (p. 317, ed. 1853). [90] Tom. vi. p. 252, 1756. [91] 'Discours sur la Nature des Animaux,' vol. iv. and p. 113 of this vol. [92] Tom. vii. p. 9, 1758. [93] Tom. vii. p. 10, 1758. [94] Tom. vii. p. 12, 1758. [95] Tom. vii. p. 14, 1758 [96] Tom. vii. p. 15, 1758. [97] Tom. vii. p. 19, 1758. [98] Tom. vii. p. 23, 1758. See Sténon's Discourse upon this subject. [99] Tom. ix. p. 10, 1761. [100] Tom. ix. p. 11, 1761. [101] Tom. ix. p. 68, 1761. [102] Ibid. p. 96, 1761. [103] Tom. ix. p. 107 and following pages (during which he rails at the new world generally), 1761. [104] Tom. ix. p. 127, 1761. [105] Tom. xi. p. 290, 1764 (misprinted on title-page 1754). [106] Ibid. p. 296. [107] Ibid. p. 363. [108] Ibid. p. 363. [109] Tom. xi. p. 370, 1764. [110] Ibid. xii., preface, iv. 1764. [111] Tom. xiii., preface, x. 1765. [112] Tom. xiii., preface, iv. 1765. [113] Ibid. xiii. p. 37. [114] See p. 80 of this volume. [115] Tom. xiv. p. 30, 1766. [116] Tom. xiv. p. 31, 1766. [117] Ibid. p. 32, 1766. [118] Tom. xiv. p. 38, 1766. [119] Ibid. p. 42, 1766. [120] Tom. xiv. p. 316, 1766. [121] Ibid. p. 317. [122] Tom. xiv. p. 326, 1766. [123] Ibid. p. 327. [124] Tom. xiv. p. 333. [125] Ibid. p. 335, 1766. [126] See p. 80 of this volume. [127] Tom. xiv. p. 358, 1766. [128] Tom. xiv. p. 374, 1766. [129] 'Hist. Nat.,' Sup. tom. v. p. 27, 1778. [130] Sup. tom. v. p. 187, 1778. [131] Sup. tom. v. p. 250, 1778. [132] Sup. tom. v. p. 253, 1778. [133] 'Oiseaux,' tom. i., preface, v. 1770. [134] Ibid. pp. 9-11. [135] 'Oiseaux,' tom. i. pp. 394, 395. [136] Ibid. p. 396, 1771. CHAPTER XII. SKETCH OF DR. ERASMUS DARWIN'S LIFE. Proceeding now to the second of the three founders of the theory of evolution, I find, from a memoir by Dr. Dowson, that Dr. Erasmus Darwin was born at Elston, near Newark, in Nottinghamshire, on the 12th of December, 1731, being the seventh child and fourth son of Robert Darwin, "a private gentleman, who had a taste for literature and science, which he endeavoured to impart to his sons. Erasmus received his early education at Chesterfield School, and later on was entered at St. John's College, Cambridge, where he obtained a scholarship of about 16_l._ a year, and distinguished himself by his poetical exercises, which he composed with uncommon facility. He took the degree of M.B. there in 1755, and afterwards prepared himself for the practice of medicine by attendance on the lectures of Dr. Hunter in London, and a course of studies in Edinburgh. "He first settled as a physician at Nottingham; but meeting with no success there, he removed in the autumn of 1756, his twenty-fifth year, to Lichfield, where he was more fortunate; for a few weeks after his arrival, to use the words of Miss Seward, 'he brilliantly opened his career of fame.' A young gentleman of family and fortune lay sick of a dangerous fever. A physician who had for many years possessed the confidence of Lichfield and the neighbourhood attended, but at length pronounced the case hopeless, and took his leave. Dr. Darwin was then called in, and by 'a reverse and entirely novel kind of treatment' the patient recovered."[137] Of Dr. Darwin's personal appearance Miss Seward says:-- "He was somewhat above the middle size; his form athletic, and inclined to corpulence; his limbs were too heavy for exact proportion; the traces of a severe smallpox disfigured features and a countenance which, when they were not animated by social pleasure, were rather saturnine than sprightly; a stoop in the shoulders, and the then professional appendage--a large full-bottomed wig--gave at that early period of life an appearance of nearly twice the years he bore. Florid health and the earnest of good humour, a funny smile on entering a room and on first accosting his friends, rendered in his youth that exterior agreeable, to which beauty and symmetry had not been propitious. "He stammered extremely, but whatever he said, whether gravely or in jest, was always well worth waiting for, though the inevitable impression it made might not be always pleasant to individual self-love. Conscious of great native elevation above the general standard of intellect, he became early in life sore upon opposition, whether in argument or conduct, and always resented it by sarcasm of very keen edge. Nor was he less impatient of the sallies of egotism and vanity, even when they were in so slight a degree that strict politeness would rather tolerate than ridicule them. Dr. Darwin seldom failed to present their caricature in jocose but wounding irony. If these ingredients of colloquial despotism were discernible in _unworn_ existence, they increased as it advanced, fed by an ever growing reputation within and without the pale of medicine."[138] I imagine that this portrait is somewhat too harshly drawn. Dr. Darwin's taste for English wines is the worst trait which I have been able to discover in his character. On this head Miss Seward tells us that "he despised the prejudice which deems foreign wines more wholesome than the wines of the country. 'If you must drink wine,' said he, 'let it be home-made.'" "It is well known," she continues, "that Dr. Darwin's influence and example have sobered the county of Derby; that intemperance in fermented fluid of every species is almost unknown among its gentlemen,"[139] which, if he limited them to cowslip wine, is hardly to be wondered at. Dr. Dowson, quoting Miss Edgeworth, says that Dr. Darwin attributed almost all the diseases of the upper classes to the too great use of fermented liquors. "This opinion he supported in his writings with the force of his eloquence and reason; and still more in conversation by all those powers of wit, satire, and peculiar humour, which never appeared fully to the public in his works, but which gained him strong ascendancy in private society.... When he heard that my father was bilious, he suspected that this must be the consequence of his having, since his residence in Ireland, and in compliance with the fashion of the country, indulged too freely in drinking. His letter, I remember, concluded with, 'Farewell, my dear friend; God keep you from whisky--if He can.'"[140] On the other hand, Dr. Darwin seems to have been a very large eater. "Acid fruits with sugar, and all sorts of creams and butter were his luxuries; but he always ate plentifully of animal food. This liberal alimentary regimen he prescribed to people of every age where unvitiated appetite rendered them capable of following it; even to infants." Dr. Dowson writes:-- "I have mentioned already that he had in his carriage a receptacle for paper and pencils, with which he wrote as he travelled, and in one corner a pile of books; but he had also a receptacle for a knife, fork, and spoon, and in the other corner a hamper, containing fruit and sweetmeats, cream and sugar. He provided also for his horses by having a large pail lashed to his carriage for watering them, as well as hay and oats to be eaten on the road. Mrs. Schimmelpenninck says that when he came on a professional visit to her father's house they had, as was the custom whenever he came, 'a luncheon-table set out with hothouse fruits and West India sweetmeats, clotted cream, stilton cheese, &c. While the conversation went on, the dishes in his vicinity were rapidly emptied, and what,' she adds, 'was my astonishment when, at the end of the three hours during which the meal had lasted, he expressed his joy at hearing the dressing bell, and hoped dinner would soon be announced.' This was not mere gluttony; he thought an abundance, or what most people would consider a superabundance of food, conducive to health. '_Eat or be eaten_' is said to have been often his medical advice. He had especially a very high opinion of the nutritive value of sugar, and said 'that if ever our improved chemistry should discover the art of making sugar from fossil or aerial matter without the assistance of vegetation, food for animals would then become as plentiful as water, and mankind might live upon the earth as thick as blades of grass, with no restraint to their numbers but want of room.'--Botanic Garden, vol. i. p. 470."[141] "Professional generosity," says Miss Seward, "distinguished Dr. Darwin's practice. Whilst resident in Lichfield he always cheerfully gave to the priest and lay vicars of its cathedral and their families _his advice_, but never took fees from any of them. Diligently also did he attend the health of the poor in that city, and afterwards at Derby, and supplied their necessities by food, and all sort of charitable assistance. In each of those towns _his_ was the cheerful board of almost open-housed hospitality, without extravagance or parade; generosity, wit, and science were his household gods."[142] Of his first marriage the following account is given:-- "In 1757 he married Miss Howard, of the Close of Lichfield, a blooming and lovely young lady of eighteen.... Mrs. Darwin's own mind, by nature so well endowed, strengthened and expanded in the friendship, conversation, and confidence of so beloved a preceptor. But alas! upon her too early youth, and too delicate constitution, the frequency of her maternal situation, during the first five years of her marriage, had probably a baneful effect. The potent skill and assiduous cares of _him_ before whom disease daily vanished from the frame of _others_, could not expel it radically from that of her he loved. It was, however, kept at bay during thirteen years. "Upon the distinguished happiness of those years she spoke with fervour to two intimate female friends in the last week of her existence, which closed at the latter end of the summer 1770. 'Do not weep for my impending fate,' said the dying angel with a smile of unaffected cheerfulness. 'In the short term of my life a great deal of happiness has been comprised. The maladies of my frame were peculiar; those of my head and stomach which no medicine could eradicate, were spasmodic and violent; and required stronger measures to render them supportable while they lasted than my constitution could sustain without injury. The periods of exemption from those pains were frequently of several days' duration, and in my intermissions I felt no indications of malady. Pain taught me the value of ease, and I enjoyed it with a glow of spirit, seldom, perhaps, felt by the habitually healthy. While Dr. Darwin combated and assuaged my disease from time to time, his indulgence to all my wishes, his active desire to see me amused and happy, proved incessant. His house, as you know, has ever been the resort of people of science and merit. If, from my husband's great and extensive practice, I had much less of his society than I wished, yet the conversation of his friends, and of my own, was ever ready to enliven the hours of his absence. As occasional malady made me doubly enjoy health, so did those frequent absences give a zest even to delight, when I could be indulged with his company. My three boys have ever been docile and affectionate. Children as they are, I could trust them with important secrets, so sacred do they hold every promise they make. They scorn deceit and falsehood of every kind, and have less selfishness than generally belongs to childhood. Married to any other man, I do not suppose I could have lived a third part of the years which I have passed with Dr. Darwin; he has prolonged my days, and he has blessed them.' "Thus died this superior woman, in the bloom of life, sincerely regretted by all who knew how to value her excellence, and _passionately_ regretted by the selected few whom she honoured with her personal and confidential friendship."[143] I find Miss Seward's pages so fascinating, that I am in danger of following her even in those parts of her work which have no bearing on Dr. Darwin. I must, however, pass over her account of Mr. Edgeworth and of his friend Mr. Day, the author of 'Sandford and Merton,' "which, by wise parents, is put into every youthful hand," but the description of Mr. Day's portrait cannot be omitted. "In the course of the year 1770, Mr. Day stood for a full-length picture to Mr. Wright, of Derby. A strong likeness and a dignified portrait were the result. Drawn in the open air, the surrounding sky is tempestuous, lurid, dark. He stands leaning his left arm against a column inscribed to Hambden (_sic_). Mr. Day looks upwards, as enthusiastically meditating on the contents of a book held in his dropped right hand. The open leaf is the oration of that virtuous patriot in the senate, against the grant of ship money, demanded by King Charles I. A flash of lightning plays in Mr. Day's hair, and illuminates the contents of the volume. The poetic fancy and what were _then_ the politics of the original, appear in the choice of subject and attitude. Dr. Darwin sat to Mr. Wright about the same period. _That_ was a simply contemplative portrait, of the most perfect resemblance."[144] . . . . . . "In the year 1768, Dr. Darwin met with an accident of irretrievable injury to the human frame. His propensity to mechanics had unfortunately led him to construct a very singular carriage. It was a platform with a seat fixed upon a very high pair of wheels, and supported in the front upon the back of the horse, by means of a kind of proboscis which, forming an arch, reached over the hind-quarters of the horse, and passed through a ring, placed on an upright piece of iron, which worked in a socket fixed in the saddle. The horse could thus move from one side of the road to the other, quartering, as it is called, at the will of the driver, whose constant attention was necessarily employed to regulate a piece of machinery contrived, but _not well_ contrived, for that purpose." I cannot help the reader to understand the foregoing description. "From this whimsical carriage, however, the doctor was several times thrown, and the last time he used it had the misfortune, from a similar accident, to break the patella of his right knee, which caused, as it must always cause, an incurable weakness in the fractured part, and a lameness not very discernible, indeed, when walking on even ground."[145] Miss Seward presently tells a story which reads as though it might have been told by Plutarch of some Greek or Roman sage. Much as we must approve of Dr. Darwin's habitual sobriety, we shall most of us be agreed that a few more such stories would have been cheaply purchased by a corresponding number of lapses on the doctor's part. Miss Seward writes:-- "Since these memoirs commenced, an odd anecdote of Dr. Darwin's early residence at Lichfield, was narrated to a friend of the author by a gentleman, who was of the party in which it happened. Mr. Sneyd, then of Bishton, and a few more gentlemen of Staffordshire, prevailed upon the doctor to join them in an expedition by water from Burton to Nottingham, and on to Newark. They had cold provisions on board, and plenty of wine. It was midsummer; the day ardent and sultry. The noon-tide meal had been made, and the glass had gone gaily round. It was one of those _few_ instances in which the medical votary of the Naiads transgressed his general and strict sobriety," in which, in fact, he may be said to have--remembered himself. "If not absolutely intoxicated, his spirits were in a high state of vinous exhilaration. On the boat approaching Nottingham, within the distance of a few fields, he surprised his companions by stepping, without any previous notice, from the boat into the middle of the river, and swimming to shore. They saw him get upon the bank, and walk coolly over the meadows towards the town: they called to him in vain, but he did not once turn his head. "Anxious lest he should take a dangerous cold by remaining in his wet clothes, and uncertain whether or not he intended to desert the party, they rowed instantly to the town at which they had not designed to have touched, and went in search of their river-god. "In passing through the market-place they saw him standing upon a tub, encircled by a crowd of people, and resisting the entreaties of an apothecary of the place, one of his old acquaintances, who was importuning him to his house, and to accept other raiments till his own could be dried. "The party on pressing through the crowd were surprised to hear him speaking without any degree of his usual stammer:--'Have I not told you, my friend, that I had drank a considerable quantity of wine before I committed myself to the river. You know my general sobriety, and as a professional man you _ought_ to know that the _unusual_ existence of internal stimulus would, in its effects upon the system, counteract the _external_ cold and moisture.'" "Then perceiving his companions near him, he nodded, smiled, and waived his hand, as enjoining them silence, thus, without hesitation, addressing the populace:-- "'Ye men of Nottingham, listen to me. You are ingenious and industrious mechanics. By your industry life's comforts are procured for yourselves and families. If you lose your health the power of being industrious will forsake you. _That_ you know, but you may _not_ know that to breathe fresh and changed air constantly, is not less necessary to preserve health than sobriety itself. Air becomes unwholesome in a few hours if the windows are shut. Open those of your sleeping rooms whenever you quit them to go to your workshops. Keep the windows of your workshops open whenever the weather is not insupportably cold. I have no _interest_ in giving you this advice; remember what I, your countryman and a physician, tell you. If you would not bring infection and disease upon yourselves, and to your wives and little ones, change the air you breathe, change it many times a day, by opening your windows.' "So saying, he stepped down from the tub, and, returning with his party to their boat, they pursued their voyage."[146] Could any missionary be more perfectly sober and sensible, or more alive to the immorality of trying to effect too sudden a modification in the organisms he was endeavouring to influence? If the men of Nottingham want a statue in their market-place, I would respectfully suggest that a subject is here afforded them. * * * * * "Dr. Johnson was several times at Lichfield on visits to Mrs. Lucy Porter, his daughter-in-law, while Dr. Darwin was one of the inhabitants. They had one or two interviews, but never afterwards sought each other. Mutual and strong dislike subsisted between them. It is curious that in Johnson's various letters to Mrs. Thrale, now Mrs. Piozzi, published by that lady after his death, many of them dated from Lichfield, the name of Darwin cannot be found, nor, indeed, that of any of the ingenious and lettered people who lived there; while of its mere common-life characters there is frequent mention, with many hints of Lichfield's intellectual barrenness, while it could boast a Darwin and other men of classical learning, poetic talents, and liberal information."[147] Here there follows a pleasant sketch of the principal Lichfield notabilities, which I am compelled to omit. "_These_ were the men," exclaims Miss Seward, "whose intellectual existence passed unnoticed by Dr. Johnson in his depreciating estimate of Lichfield talents. But Johnson liked only _worshippers_. Archdeacon Vyse, Mr. Seward, and Mr. Robinson paid all the respect and attention to Dr. Johnson, on these his visits to their town, due to his great abilities, his high reputation, and to whatever was estimable in his _mixed_ character; but they were not in the herd that 'paged his heels,' and sunk in servile silence under the force of his dogmas, when their hearts and their judgments bore _contrary_ testimony. "Certainly, however, it was an arduous hazard to the feelings of the company to oppose in the slightest degree Dr. Johnson's opinions. His stentor lungs; that combination of wit, humour, and eloquence, which 'could make the _worse_ appear the _better_ reason,' that sarcastic contempt of his antagonist, never suppressed or even softened by the due restraints of good breeding, were sufficient to close the lips in his presence, of men who could have met him in fair argument, on _any_ ground, literary or political, moral or characteristic. "Where Dr. Johnson was, Dr. Darwin had no chance of being heard, though at least his equal in genius, his superior in science; nor, indeed, from his impeded utterance, in the company of any overbearing declaimer; and he was too intellectually great to be an humble listener to Johnson. Therefore he shunned him on having experienced what manner of man he was. The surly dictator felt the mortification, and revenged it by _affecting_ to avow his disdain of powers too distinguished to be objects of _genuine_ scorn. "Dr. Darwin, in his turn, was not much more just to Dr. Johnson's genius. He uniformly spoke of him in terms which, had they been deserved, would have justified Churchill's 'immane Pomposo' as an appellation of _scorn_; since if his person was huge, and his manners pompous and violent, so were his talents vast and powerful, in a degree from which only prejudice and resentment could withhold respect. "Though Dr. Darwin's hesitation in speaking precluded his flow of colloquial eloquence, it did not impede, or at all lessen, the force of that conciser quality, _wit_. Of satiric wit he possessed a very peculiar species. It was neither the dead-doing broadside of Dr. Johnson's satire, nor the aurora borealis of Gray ... whose arch yet coy and quiet fastidiousness of taste and feeling, as recorded by Mason, glanced bright and cold through his conversation, while it seemed difficult to define its nature; and while its effects were rather _perceived_ than _felt_, exciting surprise more than mirth, and never awakening the pained sense of being the object of its ridicule. That unique in humorous verse, the Long Story, is a complete and beautiful specimen of Gray's singular vein. "Darwinian wit is not more easy to be defined; instances will best convey an idea of its character to those who never conversed with its possessor. "Dr. Darwin was conversing with a brother botanist concerning the plant kalmia, then a just imported stranger in our greenhouses and gardens. A lady who was present, concluding he had seen it, which in fact he had not, asked the doctor what were the colours of the plant. He replied, 'Madam, the kalmia has precisely the colours of a seraph's wing.' So fancifully did he express his want of consciousness concerning the appearance of a flower, whose name and rareness were all he knew of the matter. "Dr. Darwin had a large company at tea. His servant announced a stranger, lady and gentleman. The female was a conspicuous figure, ruddy, corpulent, and tall. She held by the arm a little, meek-looking, pale, effeminate man, who, from his close adherence to the side of the lady, seemed to consider himself as under her protection. "'Dr. Darwin, I seek you not as a physician, but as a _Belle Esprit_. I make this husband of mine,' and she looked down with a side glance upon the animal, 'treat me every summer with a tour through one of the British counties, to explore whatever it contains worth the attention of ingenious people. On arriving at the several inns in our route I always search out the man of the vicinity most distinguished for his genius and taste, and introduce myself, that he may direct as the objects of our examination, whatever is curious in nature, art, or science. Lichfield will be our headquarters during several days. Come, doctor, whither must we go; what must we investigate to-morrow, and the next day, and the next? Here are my tablets and pencil.' "'You arrive, madam, at a fortunate juncture. To-morrow you will have an opportunity of surveying an annual exhibition perfectly worthy your attention. To-morrow, madam, you will go to Tutbury bull-running.' "The satiric laugh with which he stammered out the last word more keenly pointed this sly, yet broad rebuke to the vanity and arrogance of her speech. She had been up amongst the boughs, and little expected they would break under her so suddenly, and with so little mercy. Her large features swelled, and her eyes flashed with anger--'I was recommended to a man of genius, and I find him insolent and ill-bred.' Then, gathering up her meek and alarmed husband, whom she had loosed when she first spoke, under the shadow of her broad arm and shoulder, she strutted out of the room. "After the departure of this curious couple, his guests told their host he had been very unmerciful. 'I chose,' replied he, 'to avenge the cause of the little man, whose nothingness was so ostentatiously displayed by his lady-wife. Her vanity has had a smart emetic. If it abates the symptoms, she will have reason to thank her physician who administered without hope of a fee.'"[148] "In the spring of 1778 the children of Colonel and Mrs. Pole of Radburn, in Derbyshire, had been injured by a dangerous quantity of the cicuta, injudiciously administered to them in the hooping-cough by a physician of the neighbourhood. Mrs. Pole brought them to the house of Dr. Darwin in Lichfield, remaining with them there a few weeks, till by his art the poison was expelled from their constitutions and their health restored. "Mrs. Pole was then in the full bloom of her youth and beauty. Agreeable features; the glow of health; a fine form, tall and graceful; playful sprightliness of manner; a benevolent heart, and maternal affection, in all its unwearied cares and touching tenderness, contributed to inspire Dr. Darwin's admiration, and to secure his esteem."[149] "In the autumn of this year" (1778) "Mrs. Pole of Radburn was taken ill; her disorder a violent fever. Dr. Darwin was called in, and never perhaps since the death of Mrs. Darwin, prescribed with such deep anxiety. Not being requested to continue in the house during the ensuing night, which he apprehended might prove critical, he passed the remaining hours till day-dawn beneath a tree opposite her apartment, watching the passing and repassing lights in the chamber. During the period in which a life so passionately valued was in danger, he paraphrased Petrarch's celebrated sonnet, narrating a dream whose prophecy was accomplished by the death of Laura. It took place the night on which the vision arose amid his slumber. Dr. Darwin extended the thought of that sonnet into the following elegy:-- "Dread dream, that, hovering in the midnight air, Clasp'd with thy dusky wing my aching head, While to imagination's startled ear Toll'd the slow bell, for bright Eliza dead. "Stretched on her sable bier, the grave beside, A snow-white shroud her breathless bosom bound, O'er her wan brow the mimic lace was tied, And loves and virtues hung their garlands round. "From those cold lips did softest accents flow? Round that pale mouth did sweetest dimples play? On this dull cheek the rose of beauty blow, And those dim eyes diffuse celestial day? "Did this cold hand, unasking Want relieve, Or wake the lyre to every rapturous sound? How sad for other's woe this breast would heave! How light this heart for other's transport bound! "Beats not the bell again?--Heavens, do I wake? Why heave my sighs, why gush my tears anew? Unreal forms my trembling doubts mistake, And frantic sorrow fears the vision true. "Dreams to Eliza bend thy airy flight, Go, tell my charmer all my tender fears, How love's fond woes alarm the silent night, And steep my pillow in unpitied tears." Unwilling as I am to extend this memoir, I must give Miss Seward's criticism on the foregoing. "The second verse of this charming elegy affords an instance of Dr. Darwin's too exclusive devotion to distinct picture in poetry; that it sometimes betrayed him into bringing objects so precisely to the eye as to lose in such precision their power of striking forcibly on the heart. The pathos in the second verse is much injured by the words 'mimic lace,' which allude to the perforated borders on the shroud. The expression is too minute for the solemnity of the subject. Certainly it cannot be natural for a shocked and agitated mind to observe, or to describe with such petty accuracy. Besides, the allusion is not sufficiently obvious. The reader pauses to consider what the poet means by 'mimic lace.' Such pauses deaden sensation and break the course of attention. A friend of the doctor's pleaded greatly that the line might run thus:-- "On her wan brow the _shadowy crape_ was tied;" but the alteration was rejected. Inattention to the rules of grammar in the first verse was also pointed out to him at the same time. The dream is addressed: "Dread dream, that clasped my aching head," but nothing is said to it, and therefore the sense is left unfinished, while the elegy proceeds to give a picture of the lifeless beauty. The same friend suggested a change which would have remedied the defect. Thus:-- "Dread _was the dream_ that in the midnight air Clasped with its dusky wing my aching head, While to" &c., &c. "Hence not only the grammatic error would have been done away, but the grating sound produced by the near alliteration of the harsh _dr_ in '_dr_ead _dr_eam' removed, by placing those words at a greater distance from each other. "This alteration was, for the same reason, rejected. The doctor would not spare the word _hovering_, which he said strengthened the picture; but surely the image ought not to be elaborately precise, by which a dream is transformed into an animal with black wings."[150] Then Mrs. Pole got well, and the doctor wrote more verses and Miss Seward more criticism. It was not for nothing that Dr. Johnson came down to Lichfield. * * * * * In 1780 Colonel Pole died, and his widow, still young, handsome, witty, and--for those days--rich, was in no want of suitors. "Colonel Pole," says Miss Seward, "had numbered twice the years of his fair wife. His temper was said to have been peevish and suspicious; yet not beneath those circumstances had her kind and cheerful attentions to him grown cold or remiss. He left her a jointure of 600_l._ per annum, a son to inherit his estate, and two female children amply portioned. "Mrs. Pole, it has already been remarked, had much vivacity and sportive humour, with very engaging frankness of temper and manners. Early in her widowhood she was rallied in a large company upon Dr. Darwin's passion for her, and was asked what she would do with her captive philosopher. 'He is not very fond of churches, I believe,' said she, 'and even if he would go there for my sake, I shall scarcely follow him. He is too old for me.' 'Nay, Madam,' was the answer, 'what are fifteen years on the right side?' She replied, with an arch smile, 'I have had so _much_ of that right side.' "This confession was thought inauspicious for the doctor's hopes, but it did not prove so. The triumph of intellect was complete."[151] Mrs. Pole had taken a strong dislike to Lichfield, and had made it a condition of her marriage that Dr. Darwin should not reside there after he had married her. In 1781, therefore, immediately after his marriage, he removed to Derby, and continued to live there till a fortnight before his death. Here he wrote 'The Botanic Garden' and a great part of the 'Zoonomia.' Those who wish for a detailed analysis of 'The Botanic Garden' can hardly do better than turn to Miss Seward's pages. Opening them at random, I find the following:-- "The mention of Brindley, the father of commercial canals, has propriety as well as happiness. Similitude for their course to the sinuous track of a serpent, produces a fine picture of a gliding animal of that species, and it is succeeded by these supremely happy lines:-- "'So with strong arms immortal Brindley leads His long canals, and parts the velvet meads; Winding in lucid lines, the watery mass Mines the firm rock, or loads the deep morass;'[152] &c. &c. &c. . . . . . . "The mechanism of the pump is next described with curious ingenuity. Common as is the machine, it is not unworthy a place in this splendid composition, as being, after the sinking of wells, the earliest of those inventions, which in situations of exterior aridness gave ready accession to water. This familiar object is illustrated by a picture of Maternal Beauty administering sustenance to her infant."[153] Here we will leave the poetical part of the 'Botanic Garden.' The notes, however, to which are "still," as Dr. Dowson says, "instructive and amusing," and contain matter which, at the time they were written, was for the most part new. Of the 'Zoonomia' there is no occasion to speak here, as a sufficient number of extracts from those parts that concern us as bearing upon evolution will be given presently. On the 18th of April, 1802, Dr. Darwin had written "one page of a very sprightly letter to Mr. Edgeworth, describing the Priory and his purposed alterations there, when the fatal signal was given. He rang the bell and ordered the servant to send Mrs. Darwin to him. She came immediately, with his daughter, Miss Emma Darwin. They saw him shivering and pale. He desired them to send to Derby for his surgeon, Mr. Hadley. They did so, but all was over before he could arrive. "It was reported at Lichfield that, perceiving himself growing rapidly worse, he said to Mrs. Darwin, 'My dear, you must bleed me instantly.' 'Alas! I dare not, lest--' 'Emma, will you? There is no time to be lost.' 'Yes, my dear father, if you will direct me.' At that moment he sank into his chair and expired."[154] Dr. Dowson gives the letter to Mr. Edgeworth, which is as follows:-- "Dear Edgeworth, "I am glad to find that you still amuse yourself with mechanism, in spite of the troubles of Ireland. "The _use_ of turning aside or downwards the claw of a table, I don't see; as it must then be reared against a wall, for it will not stand alone. If the use be for carriage, the feet may shut up, like the usual brass feet of a reflecting telescope. "We have all been now removed from Derby about a fortnight, to the Priory, and all of us like our change of situation. We have a pleasant house, a good garden, ponds full of fish, and a pleasing valley, somewhat like Shenstone's--deep, umbrageous, and with a talkative stream running down it. Our house is near the top of the valley, well screened by hills from the east and north, and open to the south, where at four miles distance we see Derby tower. "Four or more strong springs rise near the house, and have formed the valley which, like that of Petrarch, may be called Val Chiusa, as it begins, or is shut at the situation of the house. I hope you like the description, and hope farther that yourself and any part of your family will sometimes do us the pleasure of a visit. "Pray tell the authoress" (Miss Maria Edgeworth) "that the water-nymphs of our valley will be happy to assist her next novel. "My bookseller, Mr. Johnson, will not begin to print the 'Temple of Nature' till the price of paper is fixed by Parliament. I suppose the present duty is paid...." At these words Dr. Darwin's pen stopped. What followed was written on the opposite side of the paper by another hand. FOOTNOTES: [137] 'Sketch, &c., of Erasmus Darwin,' pp. 3, 4. [138] Miss Seward's 'Memoirs of Dr. Darwin,' p. 3. [139] Ibid. [140] Dr. Dowson's 'Sketch of Dr. Erasmus Darwin,' p. 50. [141] Dr. Dowson's 'Sketch of Dr. Darwin,' p. 53. [142] Miss Seward's 'Memoirs,' &c., p. 6. [143] 'Memoirs,' &c., p. 14. [144] 'Memoirs,' &c., p. 21. [145] 'Memoirs,' &c., p. 62. [146] 'Memoirs,' &c., p. 68. [147] Miss Seward's 'Memoirs,' p. 69. [148] 'Memoirs,' &c., p. 84. [149] Ibid., p. 105. [150] 'Memoirs,' &c., p. 120. [151] 'Memoirs,' &c., p. 149. [152] 'Memoirs,' &c., p. 249. [153] 'Memoirs,' &c., p. 250. [154] 'Memoirs,' &c., p. 426. CHAPTER XIII. PHILOSOPHY OF DR. ERASMUS DARWIN. Considering the wide reputation enjoyed by Dr. Darwin at the beginning of this century, it is surprising how completely he has been lost sight of. The 'Botanic Garden' was translated into Portuguese in 1803; the 'Loves of the Plants' into French and Italian in 1800 and 1805; while, as I have already said, the 'Zoonomia' had appeared some years earlier in Germany. Paley's 'Natural Theology' is written throughout at the 'Zoonomia,' though he is careful, _more suo_, never to mention this work by name. Paley's success was probably one of the chief causes of the neglect into which the Buffonian and Darwinian systems fell in this country. Dr. Darwin is as reticent about teleology as Buffon, and presumably for the same reason, but the evidence in favour of design was too obvious; Paley, therefore, with his usual keen-sightedness seized upon this weak point, and had the battle all his own way, for Dr. Darwin died the same year as that in which the 'Natural Theology' appeared. The unfortunate failure to see that evolution involves design and purpose as necessarily and far more intelligibly than the theological view of creation, has retarded our perception of many important facts for three-quarters of a century. However this may be, Dr. Darwin's name has been but little before the public during the controversies of the last thirty years. Mr. Charles Darwin, indeed, in the "historical sketch" which he has prefixed to the later editions of his 'Origin of Species,' says, "It is curious how largely my grandfather, Dr. Erasmus Darwin, anticipated the views and erroneous grounds of opinion of Lamarck in his 'Zoonomia,' vol. i. pp. 500-510, published in 1794."[155] And a few lines lower Mr. Darwin adds, "It is rather a singular instance of the manner in which similar views arise at about the same time, that Goethe in Germany, and Geoffroy St. Hilaire (as we shall immediately see) in France, came to the same conclusion on the 'Origin of Species' in the years 1794-1796." Acquaintance with Buffon's work will explain much of the singularity, while those who have any knowledge of the writings of Dr. Darwin and Étienne Geoffroy St. Hilaire will be aware that neither would admit the other as "coming to the same conclusion," or even nearly so, as himself. Dr. Darwin goes beyond his successor, Lamarck, while Étienne Geoffroy does not even go so far as Dr. Darwin's predecessor, Buffon, had thought fit to let himself be known as going. I have found no other reference to Dr. Darwin in the 'Origin of Species,' except the two just given from the same note. In the first edition I find no mention of him. The chief fault to be found with Dr. Darwin's treatise on evolution is that there is not enough of it; what there is, so far from being "erroneous," is admirable. But so great a subject should have had a book to itself, and not a mere fraction of a book. If his opponents, not venturing to dispute with him, passed over one book in silence, he should have followed it up with another, and another, and another, year by year, as Buffon and Lamarck did; it is only thus that men can expect to succeed against vested interests. Dr. Darwin could speak with a freedom that was denied to Buffon. He took Buffon at his word as well as he could, and carried out his principles to what he conceived to be their logical conclusion. This was doubtless what Buffon had desired and reckoned on, but, as I have said already, I question how far Dr. Darwin understood Buffon's humour; he does not present any of the phenomena of having done so, and therefore I am afraid he must be said to have missed it. Like Buffon, Dr. Darwin had no wish to see far beyond the obvious; he missed good things sometimes, but he gained more than he lost; he knew that it is always on the margin, as it were, of the self-evident that the greatest purchase against the nearest difficulty is obtainable. His life was not one of Herculean effort, but, like the lives of all those organisms that are most likely to develop and transmit a useful modification, it was one of well-sustained activity; it was a long-continued keeping open of the windows of his own mind, much after the advice he gave to the Nottingham weavers. Dr. Darwin knew, and, I imagine, quite instinctively, that nothing tends to oversight like overseeing. He does not trouble himself about the origin of life; as for the perceptions and reasoning faculties of animals and plants, it is enough for him that animals and plants do things which we say involve sensation and consciousness when we do them ourselves or see others do them. If, then, plants and animals appear as if they felt and understood, let the matter rest there, and let us say they feel and understand--being guided by the common use of language, rather than by any theories concerning brain and nervous system. If any young writer happens to be in want of a subject, I beg to suggest that he may find his opportunity in a 'Philosophy of the Superficial.' Though Dr. Darwin was more deeply impressed than Buffon with the oneness of personality between parents and offspring, so that these latter are not "new" creatures, but "elongations of the parents," and hence "may retain some of the habits of the parent system," he did not go on to infer definitely all that he might easily have inferred from such a pregnant premiss. He did not refer the repetition by offspring, of actions which their parents have done for many generations, but which they can never have seen those parents do, to the memory (in the strict sense of the word) of their having done those actions when they were in the persons of their parents; which memory, though dormant until awakened by the presence of associated ideas, becomes promptly kindled into activity when a sufficient number of these ideas are reproduced. This, I gather, is the theory put forward by Professor Hering, of whose work, however, I know no more than is told us by Professor Ray Lankester in an article which, appeared in 'Nature,' July 13th, 1876. This theory seems to be adopted by Professor Haeckel, and to receive support from Professor Ray Lankester himself. Knowing no German, I have been unable to make myself acquainted with Professor Hering's position in detail, but its similarity to, if not identity with, that taken by myself subsequently, but independently, in 'Life and Habit,' seems sufficiently established by the following extracts; it is to be wished, however, that a full account of this lecture were accessible to English readers. The extracts are as follows:-- "Professor Hering has the merit of introducing some striking phraseology into his treatment of the subject which serves to emphasize the leading idea. He points out that since all transmission of 'qualities' from cell to cell in the growth and repair of one and the same organ, or from parent to offspring, is a transmission of vibrations or affections of material particles, whether these qualities manifest themselves as form, or as a facility for entering on a given series of vibrations, we may speak of all such phenomena as 'memory,' whether it be the conscious memory exhibited by the nerve cells of the brain or the unconscious memory we call habit, or the inherited memory we call instinct; or whether, again, it be the reproduction of parental form and minute structure. All equally may be called the 'memory of living matter.' From the earliest existence of protoplasm to the present day the memory of living matter is continuous. Though individuals die, the universal memory of living matter is carried on. "Professor Hering, in short, helps us to a comprehensive conception of the nature of heredity and adaptation, by giving us the term 'memory' conscious or unconscious, for the continuity of Mr. Herbert Spencer's polar forces, or polarities of physiological units. . . . . . . "The undulatory movement of the plastidules is the key to the mechanical explanation of all the essential phenomena of life. The plastidules are liable to have their undulations affected by every external force, and, once modified, the movement does not return to its pristine condition. By assimilation they continually increase to a certain point in size, and then divide, and thus perpetuate in the undulatory movement of successive generations, the impressions or resultants due to the action of external agencies on individual plastidules. This is Memory. All plastidules possess memory; and Memory which we see in its ultimate analysis is identical with reproduction, is the distinguishing feature of the plastidule; is that which it alone of all molecules possesses, in addition to the ordinary properties of the physicist's molecule; is, in fact, that which distinguishes it as vital. To the sensitiveness of the movement of plastidules is due Variability--to their unconscious Memory the power of Hereditary Transmission. As we know them to-day they may 'have learnt little, and forgotten nothing' in one organism, and 'have learnt much, and forgotten much' in another; but in all, their memory if sometimes fragmentary, yet reaches back to the dawn of life upon the earth.--E. Ray Lankester." Nothing can well be plainer and more uncompromising than the above. Professor Hering would, I gather, no less than myself, refer the building of its nest by a bird to the intense--but unconscious, owing to its very perfection and intensity--recollection by the bird of the nests it built when it was in the persons of its ancestors; this memory would begin to stimulate action when the surrounding associations, such as temperature, state of vegetation, &c., reminded it of the time when it had been in the habit of beginning to build in countless past generations. Dr. Darwin does not go so far as this. He says that wild birds choose spring as their building time "from their _acquired_ knowledge that the mild temperature of the air is more convenient for hatching their eggs," and a little lower down he speaks of the fact that graminivorous animals generally produce their young in spring, as "part of the traditional knowledge which they learn _from the example_ of their parents."[156] Again he says, that birds "seem to be instructed how to build their nests _from their observation_ of that in which they were educated, and from their knowledge of those things that are most agreeable to their touch in respect to warmth, cleanliness, and stability." Had Dr. Darwin laid firmly hold of two superficial facts concerning memory which we can all of us test for ourselves--I mean its dormancy until kindled by the return of a sufficient number of associated ideas, and its unselfconsciousness upon becoming intense and perfect--and had he connected these two facts with the unity of life through successive generations--an idea which plainly haunted him--he would have been saved from having to refer instinct to imitation, in the face of the fact that in a thousand instances the creature imitating can never have seen its model, save when it was a part of its parents,--seeing what they saw, doing what they did, feeling as they felt, and remembering what they remembered. Miss Seward tells us that Dr. Darwin read his chapter on instinct "to a lady who was in the habit of rearing canary birds. She observed that the pair which he then saw building their nest in her cage, were a male and female, who had been hatched and reared in that very _cage_, and were not in existence when the mossy cradle was fabricated in which _they_ first saw light." She asked him, and quite reasonably, "how, upon his principle of imitation, he could account for the nest he then saw building, being constructed even to the precise disposal of every hair and shred of wool upon the model of _that_ in which the pair were born, and on which every other canary bird's nest is constructed, when the proper materials are furnished. That of the pyefinch," she added, "is of much compacter form, warmer, and more comfortable. Pull one of these nests to pieces for its materials; and place another nest before these canary birds as a pattern, and see if they will make the slightest attempt to imitate their model! No, the result of their labour will, upon instinctive hereditary impulse, be exactly the slovenly little mansion of their race, the same with that which their parents built before themselves were hatched. The Doctor could not do away the force of that single fact, with which his system was incompatible, yet he maintained that system with philosophic sturdiness, though experience brought confutation from a thousand sources."[157] As commonly happens in such disputes, both were right and both were wrong. The lady was right in refusing to refer instinct to imitation, and the Doctor was right in maintaining reason and instinct to be but different degrees of perfection of the same mental processes. Had he substituted "memory" for "imitation," and asked the lady to define "sameness" or "personal identity," he would have soon secured his victory. The main fact, compared with which all else is a matter of detail, is the admission that instinct is only reason become habitual. This admission involves, consciously or unconsciously, the admission of all the principles contended for in 'Life and Habit'; principles which, if admitted, make the facts of heredity intelligible by showing that they are of the same character as other facts which we call intelligible, but denial of which makes nonsense of half the terms in common use concerning it. For the view that instinct is habitual reason involves sameness of personality and memory as common to parents and offspring; it involves also the latency of that memory till rekindled by the return of a sufficient number of its associated ideas, and points the unconsciousness with which habitual actions are performed. These principles being grasped, the infertility _inter se_ of widely distant species, the commonly observed sterility of hybrids, the sterility of certain animals and plants under confinement, the phenomena of old age as well as those of growth, and the principle which underlies longevity and alternate generations, follow logically and coherently, as I showed in 'Life and Habit.' Moreover, we find that the terms in common use show an unconscious sense that some such view as I have insisted on was wanted and would come, for we find them made and to hand already; few if any will require altering; all that is necessary is to take common words according to their common meanings. Dr. Darwin is very good on this head. Here, as everywhere throughout his work, if things or qualities appear to resemble one another sufficiently and without such traits of unlikeness, on closer inspection, as shall destroy the likeness which was apparent at first, he connects them, all theories notwithstanding. I have given two instances of his manner of looking at instinct and reason.[158] "If these are not," he concludes, "deductions _from their own previous experience, or observation_, all the actions of mankind must be resolved into instincts."[159] If by "previous experience" we could be sure that Dr. Darwin persistently meant "previous experience in the persons of their ancestors," he would be in an impregnable position. As it is, we feel that though he had caught sight of the truth, and had even held it in his hands, yet somehow or other it just managed to slip through his fingers. Again he writes:-- "So flies burn themselves in candles, deceived like mankind by the misapplication of their knowledge." Again:-- "An ingenious philosopher has lately denied that animals can enter into contracts, and thinks this an essential difference between them and the human creature: but does not daily observation convince us that they form contracts of friendship with each other and with mankind? When puppies and kittens play together is there not a tacit contract that they will not hurt each other? And does not your favourite dog expect you should give him his daily food for his services and attention to you? And thus barters his love for your protection? In the same manner that all contracts are made among men that do not understand each other's arbitrary language."[160] One more extract from a chapter full of excellent passages must suffice. "One circumstance I shall relate which fell under my own eye, and showed the power of reason in a wasp, as it is exercised among men. A wasp on a gravel walk had caught a fly nearly as large as himself; kneeling on the ground, I observed him separate the tail and the head from the body part, to which the wings were attached. He then took the body part in his paws, and rose about two feet from the ground with it; but a gentle breeze wafting the wings of the fly turned him round in the air, and he settled again with his prey upon the gravel. I then distinctly observed him cut off with his mouth first one of the wings and then the other, after which he flew away with it, unmolested by the wind. "Go, proud reasoner, and call the worm thy sister!"[161] Dr. Darwin's views on the essential unity of animal and vegetable life are put forward in the following admirable chapter on "Vegetable Animation," which I will give in full, and which is confirmed in all important respects by the latest conclusions of our best modern scientists, so, at least, I gather from Mr. Francis Darwin's interesting lecture.[162] "I. 1. The fibres of the vegetable world, as well as those of the animal, are excitable into a variety of motion by irritations of external objects. This appears particularly in the mimosa or sensitive plant, whose leaves contract on the slightest injury: the _Dionæa muscipula_, which was lately brought over from the marshes of America, presents us with another curious instance of vegetable irritability; its leaves are armed with spines on their upper edge, and are spread on the ground around the stem; when an insect creeps on any of them in its passage to the flower or seed, the leaf shuts up like a steel rat-trap, and destroys its enemy.[163] "The various secretions of vegetables as of odour, fruit, gum, resin, wax, honey, seem brought about in the same manner as in the glands of animals; the tasteless moisture of the earth is converted by the hop plant into a bitter juice; as by the caterpillar in the nutshell, the sweet powder is converted into a bitter powder. While the power of absorption in the roots and barks of vegetables is excited into action by the fluids applied to their mouths like the lacteals and lymphatics of animals. "2. The individuals of the vegetable world may be considered as inferior or less perfect animals; a tree is a congeries of many living buds, and in this respect resembles the branches of the coralline, which are a congeries of a multitude of animals. Each of these buds of a tree has its proper leaves or petals for lungs, produces its viviparous or its oviparous offspring in buds or seeds; has its own roots, which, extending down the stem of the tree, are interwoven with the roots of the other buds, and form the bark, which is the only living part of the stem, is annually renewed and is superinduced upon the former bark, which then dies, and, with its stagnated juices gradually hardening into wood, forms the concentric circles which we see in blocks of timber. "The following circumstances evince the individuality of the buds of trees. First, there are many trees whose whole internal wood is perished, and yet the branches are vegete and healthy. Secondly, the fibres of the bark of trees are chiefly longitudinal, resembling roots, as is beautifully seen in those prepared barks that were lately brought from Otaheita. Thirdly, in horizontal wounds of the bark of trees, the fibres of the upper lip are always elongated downwards like roots, but those of the lower lip do not approach to meet them. Fourthly, if you wrap wet moss round any joint of a vine, or cover it with moist earth, roots will shoot out from it. Fifthly, by the inoculation or engrafting of trees many fruits are produced from one stem. Sixthly, a new tree is produced from a branch plucked from an old one and set in the ground. Whence it appears that the buds of deciduous trees are so many annual plants, that the bark is a contexture of the roots of each individual bud, and that the internal wood is of no other use but to support them in the air, and that thus they resemble the animal world in their individuality. "The irritability of plants, like that of animals, appears liable to be increased or decreased by habit; for those trees or shrubs which are brought from a colder climate to a warmer, put out their leaves and blossoms a fortnight sooner than the indigenous ones. "Professor Kalm, in his travels in New York, observes that the apple trees brought from England blossom a fortnight sooner than the native ones. In our country, the shrubs that are brought a degree or two from the north are observed to flourish better than those which come from the south. The Siberian barley and cabbage are said to grow larger in this climate than the similar more southern vegetables; and our hoards of roots, as of potatoes and onions, germinate with less heat in spring, after they have been accustomed to the winter's cold, than in autumn, after the summer's heat. "II. The stamens and pistils of flowers show evident marks of sensibility, not only from many of the stamens and some pistils approaching towards each other at the season of impregnation, but from many of them closing their petals and calyxes during the cold part of the day. For this cannot be ascribed to irritation, because cold means a defect of the stimulus of heat; but as the want of accustomed stimuli produces pain, as in coldness, hunger, and thirst of animals, these motions of vegetables in closing up their flowers must be ascribed to the disagreeable sensation, and not to the irritation of cold. Others close up their leaves during darkness, which, like the former, cannot be owing to irritation, as the irritating material is withdrawn. "The approach of the anthers in many flowers to the stigmas, and of the pistils of some flowers to the anthers, must be ascribed to the passion of love, and hence belongs to sensation, not to irritation. "III. That the vegetable world possesses some degree of voluntary powers appears from their necessity to sleep, which we have shown in Section XVIII. to consist in the temporary abolition of voluntary power. This voluntary power seems to be exerted in the circular movement of the tendrils of the vines, and other climbing vegetables; or in the efforts to turn the upper surfaces of their leaves, or their flowers, to the light. "IV. The associations of fibrous motions are observable in the vegetable world as well as in the animal. The divisions of the leaves of the sensitive plant have been accustomed to contract at the same time from the absence of light; hence, if by any other circumstance, as a slight stroke or injury, one division is irritated into contraction, the neighbouring ones contract also from their motions being associated with those of the irritated part. So the various stamina of the class of syngenesia have been accustomed to contract together in the evening, and thence if you stimulate any one of them with a pin, according to the experiment of M. Colvolo, they all contract from their acquired associations. "To evince that the collapsing of the sensitive plant is not owing to any mechanical vibrations propagated along the whole branch when a single leaf is struck with the finger, a leaf of it was slit with sharp scissors, with as little disturbance as possible, and some seconds of time passed before the plant seemed sensible of the injury, and then the whole branch collapsed as far as the principal stem. This experiment was repeated several times with the least possible impulse to the plant. "V. 1. For the numerous circumstances in which vegetable buds are analogous to animals, the reader is referred to the additional notes at the end of 'Botanic Garden,' Part I. It is there shown that the roots of vegetables resemble the lacteal system of animals; the sap vessels in the early spring, before their leaves expand, are analogous to the placental vessels of the foetus; that the leaves of land plants resemble lungs, and those of aquatic plants the gills of fish; that there are other systems of vessels resembling the vena portarum of quadrupeds, or the aorta of fish; that the digestive power of vegetables is similar to that of animals converting the fluids which they absorb into sugar;[164] that their seeds resemble the eggs of animals, and their buds and bulbs their viviparous offspring; and lastly, that the anthers and stigmas are real animals attached to their parent tree like polypi or coral insects, but capable of spontaneous motion; that they are affected with the passion of love, and furnished with powers of reproducing their species, and are fed with honey like the moths and butterflies which plunder their nectaries.[165] "The male flowers of Vallisneria approach still nearer to apparent animality, as they detach themselves from the parent plant, and float on the surface of the water to the female ones.[166] Other flowers of the classes of monoecia and dioecia, and polygamia discharge the fecundating farina, which, floating in the air, is carried to the stigma of the female flowers, and that at considerable distances. Can this be effected by any specific attraction? Or, like the diffusion of the odorous particles of flowers, is it left to the currents of the winds, and the accidental miscarriages of it counteracted by the quantity of its production? "2. This leads us to a curious inquiry, whether vegetables have ideas of external things? As all our ideas are originally received by our senses, the question may be changed to whether vegetables possess any organs of sense? Certain it is that they possess a sense of heat and cold, another of moisture and dryness, and another of light and darkness, for they close their petals occasionally from the presence of cold, moisture, or darkness. And it has been already shown that these actions cannot be performed simply from irritation, because cold and darkness are negative quantities, and on that account sensation, or volition are implied, and in consequence a sensorium or union of their nerves. So when we go into the light we contract the iris; not from any stimulus of the light on the fine muscles of the iris, but from its motions being associated with the sensation of too much light upon the retina, which could not take place without a sensorium or centre of union of the nerves of the iris, with those of vision.[167] "Besides these organs of sense, which distinguish cold, moisture, and darkness, the leaves of mimosa, and of dionæa, and of drosera, and the stamens of many flowers, as of the berbery, and the numerous class of syngenesia, are sensible to mechanic impact, that is, they possess a sense of touch, as well as a common sensorium, by the medium of which their muscles are excited into action. Lastly, in many flowers the anthers, when mature, approach the stigma, in others the female organ approaches to the male. In a plant of collinsonia, a branch of which is now before me, the two yellow stamens are about three-eighths of an inch high, and diverge from each other at an angle of about fifteen degrees, the purple style is half an inch high, and in some flowers is now applied to the stamen on the right hand, and in others to that of the left; and will, I suppose, change place to-morrow in those, where the anthers have not yet effused their powder. "I ask by what means are the anthers in many flowers and stigmas in other flowers directed to find their paramours? How do either of them know that the other exists in their vicinity? Is this curious kind of storge produced by mechanic attraction, or by the sensation of love? The latter opinion is supported by the strongest analogy, because a reproduction of the species is the consequence; and then another organ of sense must be wanted to direct these vegetable amourettes to find each other, one probably analogous to our sense of smell, which in the animal world directs the new-born infant to its source of nourishment, and they may thus possess a faculty of perceiving as well as of producing odours. "Thus, besides a kind of taste at the extremity of their roots, similar to that of the extremities of our lacteal vessels, for the purpose of selecting their proper food, and besides different kinds of irritability residing in the various glands, which separate honey, wax, resin, and other juices from their blood; vegetable life seems to possess an organ of sense to distinguish the variations of heat, another to distinguish the varying degrees of moisture, another of light, another of touch, and probably another analogous to our sense of smell. To these must be added the indubitable evidence of their passion of love, and I think we may truly conclude that they are furnished with a common sensorium for each bud, and that they must occasionally repeat those perceptions, either in their dreams or waking hours, and consequently possess ideas of so many of the properties of the external world, and of their own existence."[168] FOOTNOTES: [155] 'Origin of Species,' note on p. xiv. [156] 'Zoonomia,' vol. i. p. 170. [157] Miss Seward's 'Memoirs,' &c., p. 491. [158] See p. 116 of this volume. [159] 'Zoonomia,' vol. i. p. 184. [160] 'Zoonomia,' p. 171. [161] 'Zoonomia,' p. 187. [162] 'Nature,' March 14 and 21, 1878. [163] See 'Botanic Garden,' part ii., note on Silene. [164] 'On the Digestive Powers of Plants.' See Mr. Francis Darwin's lecture, already referred to. [165] See 'Botanic Garden, part i., add. note, p. xxxix. [166] Ibid., part ii., art. "Vallisneria." [167] See 'Botanic Garden,' part i. cant 3, l. 440. [168] 'Zoonomia,' vol. i. p. 107. CHAPTER XIV. FULLER QUOTATIONS FROM THE 'ZOONOMIA.' The following are the passages in the 'Zoonomia' which have the most important bearing on evolution:-- "The ingenious Dr. Hartley, in his work on man, and some other philosophers have been of opinion, that our immortal part acquires during this life certain habits of action or of sentiment which become for ever indissoluble, continuing after death in a future state of existence; and add that if these habits are of the malevolent kind, they must render their possessor miserable even in Heaven. I would apply this ingenious idea to the generation or production of the embryon or new animal, which partakes so much of the form and propensities of its parent. "_Owing to the imperfection of language the offspring is termed a new animal, but is in truth a branch or elongation of the parent, since a part of the embryon-animal is, or was, a part of the parent, and therefore in strict language, cannot be said to be entirely new at the time of its production; and, therefore, it may retain some of the habits of the parent system._ "At the earliest period of its existence the embryon would seem to consist of a living filament with certain capabilities of irritation, sensation, volition, and association, and also with some acquired habits or propensities peculiar to the parents; the former of these are in common with other animals; the latter seem to distinguish or produce the kind of animal, whether man or quadruped, with the similarity of feature or form to the parent."[169] * * * * * Going on to describe the gradual development of the embryo, Dr. Darwin continues:-- "As the want of this oxygenation of the blood is perpetual (as appears from the incessant necessity of breathing by lungs or gills), the vessels become extended by the efforts of pain or desire to seek this necessary object of oxygenation, and to remove the disagreeable sensations which this want occasions."[170] . . . . . . "The lateral production of plants by wires, while each new plant is thus chained to its parent, and continues to put forth another and another as the wire creeps onward on the ground, is exactly resembled by the tape-worm or tænia, so often found in the bowels, stretching itself in a chain quite from the stomach to the rectum. Linnæus asserts 'that it grows old at one extremity, while it continues to generate younger ones at the other, proceeding _ad infinitum_ like a sort of grass; the separate joints are called gourd worms, and propagate new joints like the parent without end, each joint being furnished with its proper mouth and organs of digestion.'"[171] . . . . . . "Many ingenious philosophers have found so great difficulty in conceiving the manner of the reproduction of animals, that they have supposed all the numerous progeny to have existed in miniature in the animal originally created; and that these infinitely minute forms are only evolved or distended, as the embryon increases in the womb. This idea, besides its being unsupported by any analogy we are acquainted with, ascribes a greater tenuity to organized matter than we can readily admit; as these included embryons are supposed each of them to consist of the various and complicate parts of animal bodies, they must possess a much greater degree of minuteness than that which was ascribed to the devils which tempted St. Anthony, of whom 20,000 were said to have been able to dance a saraband on the point of the finest needle without incommoding one another."[172] . . . . . . "I conceive the primordium or rudiment of the embryon as secreted from the blood of the parent to consist of a simple living filament as a muscular fibre; which I suppose to be an extremity of a nerve of locomotion, as a fibre of the retina is an extremity of a nerve of sensation; as, for instance, one of the fibrils which compose the mouth of an absorbent vessel. I suppose this living filament of whatever form it may be, whether sphere, cube, or cylinder, to be endued with the capability of being excited into action by certain kinds of stimulus. By the stimulus of the surrounding fluid in which it is received from the male it may bend into a ring, and thus form the beginning of a tube. Such moving filaments and such rings are described by those who have attended to microscopic animalculæ. This living ring may now embrace or absorb a nutritive particle of the fluid in which it swims; and by drawing it into its pores, or joining it by compression to its extremities, may increase its own length or crassitude, and by degrees the living ring may become a living tube. "With this new organization, or accretion of parts, new kinds of irritability may commence; for so long as there was but one living organ it could only be supposed to possess irritability; since sensibility may be conceived to be an extension of the effect of irritability over the rest of the system. These new kinds of irritability and of sensibility in consequence of new organization appear from variety of facts in the more mature animals; thus ... the lungs must be previously formed before their exertions to obtain fresh air can exist; the throat, or oesophagus, must be formed previous to the sensation or appetites of hunger and thirst, one of which seems to reside at the upper end and the other at the lower end of that canal."[173] It seems to me Dr. Darwin is wrong in supposing that the organ must have preceded the power to use it. The organ and its use--the desire to do and the power to do--have always gone hand in hand, the organism finding itself able to do more according as it advanced its desires, and desiring to do more simultaneously with any increase in power, so that neither appetency nor organism can claim precedence, but power and desire must be considered as Siamese twins begotten together, conceived together, born together, and inseparable always from each other. At the same time they are torn by mutual jealousy; each claims, with some vain show of reason, to have been the elder brother; each intrigues incessantly from the beginning to the end of time to prevent the other from outstripping him; each is in turn successful, but each is doomed to death with the extinction of the other. "So inflamed tendons and membranes, and even bones, acquire new sensations; and the parts of mutilated animals, as of wounded snails and polypi and crabs, are reproduced; and at the same time acquire sensations adapted to their situation. Thus when the head of a snail is reproduced after decollation with a sharp razor, those curious telescopic eyes are also reproduced, and acquire their sensibility to light, as well as their adapted muscles for retraction on the approach of injury. "With every change, therefore, of organic form or addition of organic parts, I suppose a new kind of irritability or of sensibility to be produced; such varieties of irritability or of sensibility exist in our adult state in the glands; every one of which is furnished with an irritability or a taste or appetency, and a consequent mode of action peculiar to itself. "In this manner I conceive the vessels of the jaws to produce those of the teeth; those of the fingers to produce the nails; those of the skin to produce the hair; in the same manner as afterwards, about the age of puberty, the beard and other great changes in the form of the body and disposition of the mind are produced in consequence of new developments; for, if the animal is deprived of these developments, those changes do not take place. These changes I believe to be formed not by elongation or distension of primeval stamina, but by apposition of parts; as the mature crab fish when deprived of a limb, in a certain space of time, has power to regenerate it; and the tadpole puts forth its feet after its long exclusion from the spawn, and the caterpillar in changing into a butterfly acquires a new form with new powers, new sensations, and new desires."[174] . . . . . . "From hence I conclude that with the acquisition of new parts, new sensations and new desires, as well as new powers are produced; and this by accretion to the old ones and not by distension of them. And finally, that the most essential parts of the system, as the brain for the purpose of distributing the powers of life, and the placenta for the purpose of oxygenating the blood, and the additional absorbent vessels, for the purpose of acquiring aliment, are first formed by the irritations above mentioned, and by the pleasurable sensations attending those irritations, and by the exertions in consequence of painful sensations similar to those of hunger and suffocation. After these an apparatus of limbs for future uses, or for the purpose of moving the body in its present natant state, and of lungs for future respiration, and of _testes_ for future reproduction, are formed by the irritations and sensations and consequent exertions of the parts previously existing, and to which the new parts are to be attached.[175] . . . . . . "The embryon" must "be supposed to be a living filament, which acquires or makes new parts, with new irritabilities as it advances in its growth."[176] . . . . . . "From this account of reproduction it appears that all animals have a similar origin, viz. a single living filament; and that the difference of their forms and qualities has arisen only from the different irritabilities and sensibilities, or voluntarities, or associabilities, of this original living filament, and perhaps in some degree from the different forms of the particles of the fluids by which it has at first been stimulated into activity."[177] . . . . . . "All animals, therefore, I contend, have a similar cause of their organization, originating from a single living filament, endued with different kinds of irritabilities and sensibilities, or of animal appetencies, which exist in every gland, and in every moving organ of the body, and are as essential to living organism as chemical affinities are to certain combinations of inanimate matter. "If I might be indulged to make a simile in a philosophical work, I should say that the animal appetencies are not only perhaps less numerous originally than the chemical affinities, but that, like these latter, they change with every fresh combination; thus vital air and azote, when combined, produce nitrous acid, which now acquires the property of dissolving silver; so that with every new additional part to the embryon, as of the throat or lungs, I suppose a new animal appetency to be produced."[178] * * * * * Here, again, it should be insisted on that neither can the "additional part" precede "the appetency," nor the appetency precede the additional part for long together--the two advance nearly _pari passu_; sometimes the power a little ahead of the desire, stimulates the desire to an activity it would not otherwise have known; as those who have more money than they once had, feel new wants which they would not have known if they had not obtained the power to gratify them; sometimes, on the other hand, the desire is a little more active than the power, and pulls the power up to itself by means of the effort made to gratify the desire--as those who want a little more of this or that than they have money to pay for, will try all manner of shifts to earn the additional money they want, unless it is so much in excess of their present means that they give up the endeavour as hopeless; but whichever gets ahead, immediately sets to work to pull the other level with it, the getting ahead either of power or desire being exclusively the work of external agencies, while the coming up level of the other is due to agencies that are incorporate with the organism itself. Thus an unusually abundant supply of food, due to causes entirely beyond the control of the individual, is an external agency; it will immediately set power a little ahead of desire. On this the individual will eat as much as it can--thus learning _pro tanto_ to be able to eat more, and to want more under ordinary circumstances--and will also breed rapidly up to the balance of the abundance. This is the work of the agencies incorporate in the organism, and will bring desire level with power again. Famine, on the other hand, puts desire ahead of power, and the incorporate agencies must either bring power up by resource and invention, or must pull desire back by eating less, both as individuals, and as the race, that is to say, by breeding less freely; for breeding is an assimilation of outside matter so closely akin to feeding, that it is only the feeding of the race, as against that of the individual. I do not think the reader will find any clearer manner of picturing to himself the development of organism than by keeping the normal growth of wealth continually in his mind. He will find few of the phenomena of organic development which have not their counterpart in the acquisition of wealth. Thus a too sudden acquisition, owing to accidental and external circumstances and due to no internal source of energy, will be commonly lost in the next few generations. So a sudden sport due to a lucky accident of soil will not generally be perpetuated if the offspring plant be restored to its normal soil. Again, if the advance in power carry power suddenly far beyond any past desire, or be far greater than any past-remembered advance of power beyond desire--then desire will not come up level easily, but only with difficulty and all manner of extravagance, such as is likely to destroy the power itself. Demand and Supply are also good illustrations. But to return to Dr. Darwin. "When we revolve in our minds," he writes, "first the great changes which we see naturally produced in animals after their nativity, as in the production of the butterfly with painted wings from the crawling caterpillar; or of the respiring frog from the subnatant tadpole; from the boy to the bearded man, from the infant girl to the woman,--in both which cases mutilation will prevent due development. "Secondly, when we think over the great changes introduced into various animals by artificial or accidental cultivation, as in horses, which we have exercised for the different purposes of strength or swiftness, in carrying burthens or in running races, or in dogs which have been cultivated for strength and courage, as the bull-dog; or for acuteness of his sense of smell, as the hound or spaniel; or for the swiftness of his foot, as the greyhound; or for his swimming in the water or for drawing snow sledges, as the rough-haired dogs of the north; or, lastly, as a play dog for children, as the lapdog; with the changes of the forms of the cattle which have been domesticated from the greatest antiquity, as camels and sheep, which have undergone so total a transformation that we are now ignorant from what species of wild animal they had their origin. Add to these the great changes of shape and colour which we daily see produced in smaller animals from our domestication of them, as rabbits or pigeons, or from the difference of climates and even of seasons; thus the sheep of warm climates are covered with hair instead of wool; and the hares and partridges of the latitudes which are long buried in snow become white during the winter months; add to these the various changes produced in the forms of mankind by their early modes of exertion, or by the diseases occasioned by their habits of life, both of which become hereditary, and that through many generations. Those who labour at the anvil, the oar, or the loom, as well as those who carry sedan chairs or who have been educated to dance upon the rope, are distinguishable by the shape of their limbs; and the diseases occasioned by intoxication deform the countenance with leprous eruptions, or the body with tumid viscera, or the joints with knots and distortions. "Thirdly, when we enumerate the great changes produced in the species of animals before their nativity, as, for example, when the offspring reproduces the effects produced upon the parent by accident or cultivation; or the changes produced by the mixture of species, as in mules; or the changes produced probably by the exuberance of nourishment supplied to the fetus, as in monstrous births with additional limbs; many of these enormities of shape are propagated and continued as a variety at least, if not as a new species of animal. I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw, and with wings to their feet; and of others without rumps. Mr. Buffon mentions a breed of dogs without tails which are common at Rome and Naples--which he supposes to have been produced by a custom long established of cutting their tails close off. There are many kinds of pigeons admired for their peculiarities which are more or less thus produced and propagated.[179] . . . . . . "When we consider all these changes of animal form and innumerable others which may be collected from the books of natural history, we cannot but be convinced that the fetus or embryon is formed by apposition of new parts, and not by the distention of a primordial nest of germs included one within another like the cups of a conjurer. "Fourthly, when we revolve in our minds the great similarity of structure which obtains in all the warm-blooded animals, as well quadrupeds, birds, and amphibious animals, as in mankind; from the mouse and bat to the elephant and whale; one is led to conclude that they have alike been produced from a similar living filament. In some this filament in its advance to maturity has acquired hands and fingers with a fine sense of touch, as in mankind. In others it has acquired claws or talons, as in tigers and eagles. In others, toes with an intervening web or membrane, as in seals and geese. In others it has acquired cloven hoofs, as in cows and swine; and whole hoofs in others, as in the horse: while in the bird kind this original living filament has put forth wings instead of arms or legs, and feathers instead of hair. In some it has protruded horns on the forehead instead of teeth in the fore part of the upper jaw; in others, tusks instead of horns; and in the others, beaks instead of either. And all this exactly as is seen daily in the transmutation of the tadpole, which acquires legs and lungs when he wants them, and loses his tail when it is no longer of service to him. "Fifthly, from their first rudiment or primordium to the termination of their lives, all animals undergo perpetual transformations; _which are in part produced by their own exertions in consequence of their desires and aversions, of their pleasures and their pains, or of irritations or of associations; and many of these acquired forms or propensities are transmitted to their posterity_. "As air and water are supplied to animals in sufficient profusion, the three great objects of desire which have changed the forms of many animals by their desires to gratify them are those of lust, hunger, and security. A great want of one part of the animal world has consisted in the desire of the exclusive possession of the females; and these have acquired weapons to combat each other for this purpose, as the very thick, shield-like, horny skin on the shoulder of the boar is a defence only against animals of his own species who strike obliquely upwards, nor are his tusks for other purposes except to defend himself, as he is not naturally a carnivorous animal. So the horns of the stag are sharp to offend his adversary, but are branched for the purpose of parrying or receiving the thrust of horns similar to his own, and have therefore been formed for the purpose of combating other stags, for the exclusive possession of the females; who are observed like the ladies in the times of chivalry to attend the car of the victor. "The birds which do not carry food to their young, and do not therefore marry, are armed with spurs for the purpose of fighting for the exclusive possession of the females, as cocks and quails. It is certain that these weapons are not provided for their defence against other adversaries, because the females of these species are without this armour. The final cause of this contest among the males seems to be _that the strongest and most active animal should propagate the species, which should thence become improved_."[180] Dr. Darwin would have been on stronger ground if he had said that the _effect_ of the contest among the males was that the fittest should survive, and hence transmit any fit modifications which had occurred to them as vitally true, rather than that the desire to attain this end had caused the contest; but either way the sentence just given is sufficient to show that he was not blind to the fact that the fittest commonly survive, and to the consequences of this fact. The use, however, of the word "thence," as well as of the expression "final cause," is loose, as Dr. Darwin would no doubt readily have admitted. Improvement in the species is due quite as much, by Dr. Darwin's own showing, to the causes which have led to such and such an animal's making itself the fittest, as to the fact that if fittest it will be more likely to survive and transmit its improvement. There have been two factors in modification; the one provides variations, the other accumulates them; neither can claim exclusive right to the word "thence," as though the modification was due to it and to it only. Dr. Darwin's use of the word "thence" here is clearly a slip, and nothing else; but it is one which brings him for the moment into the very error into which his grandson has fallen more disastrously. "Another great want," he continues, "consists in the means of procuring food, which has diversified the forms of all species of animals. Thus the nose of the swine has become hard for the purpose of turning up the soil in search of insects and of roots. The trunk of the elephant is an elongation of the nose for the purpose of pulling down the branches of trees for his food, and for taking up water without bending his knees. Beasts of prey have acquired strong jaws or talons. Cattle have acquired a rough tongue and a rough palate to pull off the blades of grass, as cows and sheep. Some birds have acquired harder beaks to crack nuts, as the parrot. Others have acquired beaks to break the harder seeds, as sparrows. Others for the softer kinds of flowers, or the buds of trees, as the finches. Other birds have acquired long beaks to penetrate the moister soils in search of insects or roots, as woodcocks, and others broad ones to filtrate the water of lakes and to retain aquatic insects. All which seem to have been gradually produced during many generations _by the perpetual endeavour of the creature to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purposes required_. "The third great want among animals is that of security, which seems to have diversified the forms of their bodies and the colour of them; these consist in the means of escaping other animals more powerful than themselves. Hence some animals have acquired wings instead of legs, as the smaller birds, for purposes of escape. Others, great length of fin or of membrane, as the flying fish and the bat. Others have acquired hard or armed shells, as the tortoise and the _Echinus marinus_. "Mr. Osbeck, a pupil of Linnæus, mentions the American frog-fish, _Lophius Histrio_, which inhabits the large floating islands of sea-weed about the Cape of Good Hope, and has fulcra resembling leaves, that the fishes of prey may mistake it for the sea-weed, which it inhabits.[181] "The contrivances for the purposes of security extend even to vegetables, as is seen in the wonderful and various means of their concealing or defending their honey from insects and their seeds from birds. On the other hand, swiftness of wing has been acquired by hawks and swallows to pursue their prey; and a proboscis of admirable structure has been acquired by the bee, the moth, and the humming bird for the purpose of plundering the nectaries of flowers. _All which seem to have been formed by the original living filament, excited into action by the necessities of the creatures which possess them_, and on which their existence depends. "From thus meditating on the great similarity of the structure of the warm-blooded animals, and at the same time of the great changes they undergo both before and after their nativity; and by considering in how minute a portion of time many of the changes of animals above described have been produced; would it be too bold to imagine that in the great length of time since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind--would it be too bold to imagine that all warm-blooded animals have arisen from one living filament, which the Great First Cause endued with animality, with the power of attaining new parts, attended with new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve, by its own inherent activity, and of delivering down those improvements by generation to its posterity world without end! "Sixthly, the cold-blooded animals, as the fish tribes, which are furnished with but one ventricle of the heart, and with gills instead of lungs, and with fins instead of feet or wings, bear a great similarity to each other; but they differ nevertheless so much in their general structure from the warm-blooded animals, that it may not seem probable at first view that the same living filament could have given origin to this kingdom of animals, as to the former. Yet are there some creatures which unite or partake of both these orders of animation, as the whales and seals; and more particularly the frog, who changes from an aquatic animal furnished with gills to an aerial one furnished with lungs. "The numerous tribes of insects without wings, from the spider to the scorpion, from the flea to the lobster; or with wings, from the gnat or the ant to the wasp and the dragon-fly, differ so totally from each other, and from the red-blooded classes above described, both in the forms of their bodies and in their modes of life; besides the organ of sense, which they seem to possess in their antennæ or horns, to which it has been thought by some naturalists that other creatures have nothing similar; that it can scarcely be supposed that this nature of animals could have been produced by the same kind of living filament as the red-blooded classes above mentioned. And yet the changes which many of them undergo in their early state to that of their maturity, are as different as one animal can be from another. As those of the gnat, which passes his early state in water, and then stretching out his new wings and expanding his new lungs, rises in the air; as of the caterpillar and bee-nymph, which feed on vegetable leaves or farina, and at length bursting from their self-formed graves, become beautiful winged inhabitants of the skies, journeying from flower to flower, and nourished by the ambrosial food of honey. "There is still another class of animals which are termed vermes by Linnæus, which are without feet or brain, and are hermaphrodites, as worms, leeches, snails, shell-fish, coralline insects, and sponges, which possess the simplest structure of all animals, and appear totally different from those already described. The simplicity of their structure, however, can afford no argument against their having been produced from a single living filament, as above contended. "Last of all, the various tribes of vegetables are to be enumerated amongst the inferior orders of animals. Of these the anthers and stigmas have already been shown to possess some organs of sense, to be nourished by honey, and to have the power of generation like insects, and have thence been announced amongst the animal kingdom in Section XIII.; and to these must be added the buds and bulbs, which constitute the viviparous offspring of vegetation. The former I suppose to be beholden to a single living filament for their seminal or amatorial procreation; and the latter to the same cause for their lateral or branching generation, which they possess in common with the polypus, tænia, and volvox, and the simplicity of which is an argument in favour of the similarity of its cause. "Linnæus supposes, in the introduction to his natural orders, that very few vegetables were at first created, and that their numbers were increased by their intermarriages, and adds, 'Suaderet hæc Creatoris leges a simplicibus ad composita.' Many other changes appear to have arisen in them by their perpetual contest for light and air above ground, and for food or moisture beneath the soil. As noted in the 'Botanic Garden,' Part II., note on Cuscuta. Other changes of vegetables from climate or other causes are remarked in the note on Curcuma in the same work. From these one might be led to imagine that each plant at first consisted of a single bulb or flower to each root, as the gentianella and daisy, and that in the contest for air and light, new buds grew on the old decaying flower-stem, shooting down their elongated roots to the ground, and that in process of ages tall trees were thus formed, and an individual bulb became a swarm of vegetables. Other plants which in this contest for light and air were too slender to rise by their own strength, learned by degrees to adhere to their neighbours, either by putting forth roots like the ivy, or by tendrils like the vine, or by spiral contortions like the honeysuckle, or by growing upon them like the mistleto, and taking nourishment from their barks, or by only lodging or adhering on them and deriving nourishment from the air as tillandsia. "Shall we then say that the vegetable living filament was originally different from that of each tribe of animals above described? And that the productive living filament of each of those tribes was different from the other? Or as the earth and ocean were probably peopled with vegetable productions long before the existence of animals; and many families of these animals, long before other families of them, shall we conjecture _that one and the same kind of living filament is and has been the cause of all organic life_?[182] . . . . . . "The late Mr. David Hume in his posthumous works places the powers of generation much above those of our boasted reason, and adds, that reason can only make a machine, as a clock or a ship, but the power of generation makes the maker of the machine; and probably from having observed that the greatest part of the earth has been formed out of organic recrements, as the immense beds of limestone, chalk, marble, from the shells of fish; and the extensive provinces of clay, sandstone, ironstone, coals, from decomposed vegetables; all of which have been first produced by generation, or by the secretion of organic life; he concludes that the world itself might have been generated rather than created; that it might have been gradually produced from very small beginnings, increasing by the activity of its inherent principles, rather than by a sudden evolution of the whole by the Almighty fire. What a magnificent idea of the infinite power of the great Architect! The Cause of causes! Parent of parents! Ens entium!"[183] FOOTNOTES: [169] 'Zoonomia,' vol. i. p. 484. [170] Ibid. p. 485. [171] Ibid. p. 493. [172] 'Zoonomia,' vol. i. p. 494. [173] 'Zoonomia,' vol. i. p. 497. [174] 'Zoonomia,' vol. i. p. 498. [175] 'Zoonomia,' vol. i. p. 500. [176] Ibid. p. 501. [177] Ibid. p. 502. [178] 'Zoonomia,' vol. i. p. 503. [179] 'Zoonomia,' vol. i. p. 505. [180] 'Zoonomia,' vol. i. p. 507. [181] 'Voyage to China,' p. 113. [182] 'Zoonomia,' vol. i. p. 511. [183] 'Zoonomia,' vol. i. p. 513. CHAPTER XV. MEMOIR OF LAMARCK. I take the following memoir of Lamarck entirely from the biographical sketch prefixed by M. Martins to his excellent edition of the 'Philosophie Zoologique.'[184] From this sketch I find that "Lamarck was born August 1, 1744, at Barenton, in Picardy, being the eleventh child of Pierre de Monet, squire of the place, a man of old family, but poor. His father intended him for the Church, the ordinary resource of younger sons at that time, and accordingly placed him under the care of the Jesuits at Amiens. But this was not his vocation: the annals of his family spoke all to him of military glory; his eldest brother had died in the breaches at the siege of Bergen-op-Zoom; two others were still serving in the army, and France was exhausting her energies in an unequal struggle. His father would not yield to his wishes, but on his death, in 1760, Lamarck was left free to take his own line, and made his way at once--upon a very bad horse--to the army of Germany, then encamped at Lippstadt in Westphalia. "He was the bearer of a letter written by Madame de Lameth, one of his neighbours in the country, and recommending him to M. de Lastic, colonel of the regiment of Beaujolais. This gentleman, on seeing before him a lad of seventeen, whose somewhat stunted growth made him look still younger than he really was, sent the youth immediately to his own quarters. The next day a battle was immediately impending, and M. de Lastic, on passing his regiment in review, saw his protégé in the first rank of a company of grenadiers. The French army was under the orders of the Marshal de Broglie and of the Prince de Soubise; the allied troops were commanded by Ferdinand of Brunswick. The two French generals were beaten owing to their divided counsels, and Lamarck's company, almost annihilated by the enemy's fire, was forgotten in the confusion of the retreat. All the officers, commissioned and non-commissioned, were killed, and only fourteen men out of the whole company remained alive: the eldest proposed to retreat, but Lamarck, improvising himself as commander, declared that they ought not to retire without orders. Presently the colonel seeing that this company did not rally sent an orderly officer who made his way up to it by protected paths. Next day Lamarck was made an officer, and shortly afterwards lieutenant. "Fortunately for science," continues M. Martins, "this brilliant _début_ was not to decide his career. After peace had been signed he was sent into garrison at Toulon and Monaco, where an inflammation of the lymphatic ganglions of the neck necessitated an operation which left him deeply scarred for life. "The vegetation in the neighbourhood of Toulon and Monaco now arrested the young officer's attention. He had already derived some little knowledge of botany from the '_Traité des Plantes usuelles_' of Chomel. Having retired from the service, and having nothing beyond his modest pension of four hundred francs a year, he took a situation at Paris with a banker; but drawn irresistibly to the study of nature, he used to study from his attic window the forms and movements of clouds, and made himself familiar with the plants in the Jardin du Roi or in the public gardens. He began to feel that he was on his right path, and understood, as Voltaire said of Condorcet, that discoveries of permanent value could make him no less illustrious than military glory. "Dissatisfied with the botanical systems of his time, in six months he wrote his '_Flore française_,' preceded by the '_Clé dichotomique_,' with the help of which it is easy even for a beginner to arrive with certainty at the name of the plant before him." Of this work, M. Martins tells us in a note, that the second edition, published by Candolle in 1815, is still the standard work on French plants. "In 1778 Rousseau had brought botany into vogue. Women and men of fashion took to it. Buffon had the three volumes of '_Flore française_' printed at the royal press, and in the following year Lamarck entered the Academy of Sciences. Buffon being anxious that his son should travel, gave him Lamarck for his companion and tutor. He thus made a trip through Holland, Germany, and Hungary, and became acquainted with Gleditsch at Berlin, with Jacquin at Vienna, and with Murray at Gottingen. "The '_Encyclopédie méthodique_,' begun by Diderot and D'Alembert, was not yet completed. For this work Lamarck wrote four volumes, describing all the then known plants whose names began with the letters from A to P. This great work was completed by Poiret, and comprises twelve volumes, which appeared between the years 1783 and 1817. A still more important work, also part of the Encyclopedia, and continually quoted by botanists, is the '_Illustration des Genres_.' In this work Lamarck describes two thousand _genera_, and illustrates them, according to the title-page, with nine hundred engravings. Only a botanist can form any idea of the research in collections, gardens, and books, which such a work must have involved. But Lamarck's activity was inexhaustible. Sonnerat returned from India in 1781 with a very large number of dried plants; no one except Lamarck thought it worth while to inspect them, and Sonnerat, charmed with his enthusiasm, gave him the whole magnificent collection. "In spite, however, of his incessant toil, Lamarck's position continued to be most precarious. He lived by his pen, as a publisher's hack, and it was with difficulty that he obtained even the poorly paid post of keeper of the king's cabinet of dried plants. Like most other naturalists he had thus to contend with incessant difficulties during a period of fifteen years. "At length fortune bettered his condition while changing the direction of his labours. France was now under the Convention; what Carnot had done for the army Lakanal undertook to do for the natural sciences. At his suggestion a museum of natural history was established. Professors had been found for all the chairs save that of Zoology; but in that time of enthusiasm, so different from the present, France could find men of war and men of science wherever and whenever she had need of them. Étienne Geoffroy St. Hilaire was twenty-one years old, and was engaged in the study of mineralogy under Haüy. Daubenton said to him, 'I will undertake the responsibility for your inexperience. I have a father's authority over you. Take this professorship, and let us one day say that you have made zoology a French science.' Geoffroy accepted, and undertook the higher animals. Lakanal knew that a single professor could not suffice for the task of arranging the collections of the entire animal kingdom, and as Geoffroy was to class the vertebrate animals only, there remained the invertebrata--that is to say, insects, molluscs, worms, zoophytes--in a word, what was then the chaos of the unknown. 'Lamarck,' says M. Michelet, 'accepted the unknown.' He had devoted some attention to the study of shells with Bruguières, but he had still everything to learn, or I should perhaps say rather, everything to create in that unexplored territory into which Linnæus had declined to enter, and into which he had thus introduced none of the order he had so well known how to establish among the higher animals. "Lamarck began his course of lectures at the museum in 1794, after a year's preparation, and at once established that great division of animals into vertebrate and invertebrate, which science has ever since recognized. "Dividing the vertebrate animals--as Linnæus had already divided them--into mammals, birds, reptiles, and fishes, he divided the invertebrates into molluscs, insects, worms, echinoderms, and polyps. In 1799 he separated the crustacea from the insects, with which they had been classed hitherto; in 1800 he established the arachnids as a class distinct from the insects; in 1802 that of the annelids, a subdivision of the worms, and that of the radiata as distinct from the polyps. Time has approved the wisdom of these divisions, founded all of them upon the organic type of the creatures themselves--that is to say, upon the rational method introduced into zoology by Cuvier, Lamarck, and Geoffroy St. Hilaire. "This introduction being devoted only to Lamarck's labours as a naturalist, we will pass over certain works in which he treats of physics and chemistry. These attempts--errors of a powerful mind which thought itself able by the help of pure reason to establish truths which rest only upon experience--attempts, moreover, which were some of them but resuscitations of exploded theories, such as that of 'phlogistic'--had not even the honour of being refuted: they did not deserve to be so, and should be a warning to all those who would write upon a subject without the necessary practical knowledge. . . . . . . "At the beginning of this century there was not yet any such science as geology. People observed but little, and in lieu of observation made theories to embrace the entire globe. Lamarck made his in 1802, and twenty-three years later the judicious Cuvier still yielded to the prevailing custom in publishing his 'Discoveries on the Earth's Revolutions.' "Lamarck's merit was to have discovered that there had been no catastrophes, but that the gradual action of forces during thousands of ages accounted for the changes observable upon the face of the earth, better than any sudden and violent perturbations. 'Nature,' he writes, 'has no difficulty on the score of time; she has it always at command; it is with her a boundless space in which she has room for the greatest as for the smallest operations.'" Here we must not forget Buffon's fine passage, "Nature's great workman is Time," &c. See page 103. "Lamarck," continues M. Martins, "was the first to distinguish littoral from ocean fossils, but no one accepts his theory that oceans make their beds deeper owing to the action of the tides, and distribute themselves differently over the earth's surface without any change of level of the different parts of that surface. . . . . . . "Settling down to a single branch of science, in consequence of his professorship, Lamarck now devoted himself to the twofold labour of lecturing and classifying the collections at the museum. In 1802 he published his 'Considerations on the Organization of Living Bodies'; in 1809 his '_Philosophie Zoologique_,' a development of the 'Considerations'; and from 1816 to 1822 his Natural History of the invertebrate animals, in seven volumes. This is his great work, and, being entirely a work of description and classification, was received with the unanimous approbation of the scientific world. His 'Fossil Shells of the Neighbourhood of Paris'--a work in which his profound knowledge of existing shells enabled him to class with certainty the remains of forms that had disappeared thousands of ages ago--met also with a favourable reception. "Lamarck was fifty years old before he began to study zoology; and prolonged microscopic examinations first fatigued and at length enfeebled his eyesight. The clouds which obscured it gradually thickened, and he became quite blind. Married four times, the father of seven children, he saw his small patrimony and even his earlier savings swallowed up by one of those hazardous investments with which promoters impose on the credulity of the public. His small endowment as professor alone protected him from destitution. Men of science whom his reputation as a botanist and zoologist had attracted near him, wondered at the manner in which he was neglected. . . . . . . "He passed the last ten years of his laborious life in darkness, tended only by the affectionate care of his two daughters. The eldest wrote from his dictation part of the sixth and seventh volumes of his work on the invertebrate animals. From the time her father became confined to his room his daughter never left the house; and when first she did so after his death, she was distressed by the fresh air to which she had been so long a stranger. "Lamarck died December 18, 1829, at the age of eighty-five. Latreille and Blainville were his successors at the museum. The incredible activity of the first professor had so greatly increased the number of the known invertebrata that it was found necessary to endow two professors, where one had originally been sufficient. "His two daughters were left penniless. In the year 1832 I myself saw Mlle. Cornélie de Lamarck earning a scanty pittance by fastening dried plants on to paper, in the museum of which her father had been a professor. Many a species named and described by him must have passed under her eyes and increased the bitterness of her regret."[185] FOOTNOTES: [184] Paris, 1873. [185] Introduction Biographique to M. Martins' edition of the 'Phil. Zool.,' pp. ix-xx. CHAPTER XVI. GENERAL MISCONCEPTION CONCERNING LAMARCK--HIS PHILOSOPHICAL POSITION. "If Cuvier," says M. Isidore Geoffroy St. Hilaire,[186] "is the modern successor of Linnæus, so is Lamarck of Buffon. But Cuvier does not go so far as Linnæus, and Lamarck goes much farther than Buffon. Lamarck, moreover, took his own line, and his conjectures are not only much bolder, or rather more hazardous, but they are profoundly different from Buffon's. "It is well known that the vast labours of Lamarck were divided between botany and physical science in the eighteenth century, and between zoology and natural philosophy in the nineteenth; it is, however, less generally known that Lamarck was long a partisan of the immutability of species. It was not till 1801, when he was already old, that he freed himself from the ideas then generally prevailing. But Lamarck, having once made up his mind, never changed it; in his ripe age he exhibits all the ardour of youth in propagating and defending his new convictions. "In the three years, 1801, 1802, 1803, he enounced them twice in his lectures, and three times in his writings.[187] He returns to the subject and states his views precisely in 1806,[188] and in 1809 he devotes a great part of his principal work, the 'Philosophie Zoologique,' to their demonstration.[189] Here he might have rested and have quietly awaited the judgment of his peers; but he is too much convinced; he believes the future of science to depend so much upon his doctrine that to his dying day he feels compelled to explain it further and insist upon it. When already over seventy years of age he enounces it again, and maintains it as firmly as ever in 1815, in his 'Histoire des Animaux sans Vertèbres,' and in 1820 in his 'Système des Connaissances Positives.'[190] "This doctrine, so dearly cherished by its author, and the conception, exposition, and defence of which so laboriously occupied the second half of his scientific career, has been assuredly too much admired by some, who have forgotten that Lamarck had a precursor, and that that precursor was Buffon. It has, on the other hand, been too severely condemned by others who have involved it in its entirety in broad and sweeping condemnation. As if it were possible that so great labour on the part of so great a naturalist should have led him to 'a fantastic conclusion' only--to a 'flighty error,' and, as has been often said, though not written, to 'one absurdity the more.' Such was the language which Lamarck heard during his protracted old age, saddened alike by the weight of years and blindness; this was what people did not hesitate to utter over his grave yet barely closed, and what, indeed, they are still saying--commonly, too, without any knowledge of what Lamarck maintained, but merely repeating at second hand bad caricatures of his teaching. "When will the time come when we may see Lamarck's theory discussed--and, I may as well at once say, refuted in some important points--with at any rate the respect due to one of the most illustrious masters of our science? And when will this theory, the hardihood of which has been greatly exaggerated, become freed from the interpretations and commentaries by the false light of which so many naturalists have formed their opinion concerning it? If its author is to be condemned, let it be, at any rate, not before he has been heard."[191] It is not necessary for me to give the extracts from Lamarck which M. Isidore Geoffroy St. Hilaire quotes in order to show what he really maintained, inasmuch as they will be given at greater length in the following chapter; but I may perhaps say that I have not found M. Geoffroy refuting Lamarck in any essential point. Professor Haeckel says that to Lamarck "will always belong the immortal glory of having for the first time worked out the theory of descent as an independent scientific theory of the first order, and as the philosophical foundation of the whole science of Biology." . . . . . . "The 'Philosophie Zoologique,'" continues Professor Haeckel, "is the first connected exposition of the theory of descent carried out strictly into all its consequences; ... and with the exception of Darwin's work, which appeared exactly half a century later, we know of none which we could in this respect place by the side of the 'Philosophie Zoologique.' How far it was in advance of its time is perhaps best seen from the circumstance that it was not understood by most men, and for fifty years was not spoken of at all."[192] This is an exaggeration, both as regards the originality of Lamarck's work and the reception it has met with. It is probably more accurate to say with M. Martins that Lamarck's theory has "never yet had the honour of being discussed seriously,"[193] not, at least, in connection with the name of its originators. So completely has this been so that the author of the 'Vestiges of Creation,' even in the edition of 1860, in which he unreservedly acknowledges the adoption of Lamarck's views, not unfrequently speaks disparagingly of Lamarck himself, and never gives him his due meed of recognition. I am not, therefore, wholly displeased to find this author conceiving himself to have been treated by Mr. Charles Darwin with some of the injustice which he has himself inflicted on Lamarck. In the 1859 edition of the 'Origin of Species,' and in a very prominent place, Mr. Darwin says:--"The author of the 'Vestiges of Creation' would I presume say, that after a certain number of unknown generations, some bird had given birth to a woodpecker, and some plant to a misseltoe, and that these had been produced perfect as we now see them."[194] This is the only allusion to the 'Vestiges' which I have found in the first edition of the 'Origin of Species.' Those who have read the 1853 edition of the 'Vestiges' will not be surprised to find the author rejoining, in his edition of 1860, that it was to be regretted Mr. Darwin should have read the 'Vestiges' "nearly as much amiss as though, like its declared opponents, he had an interest in misunderstanding it." And a little lower he adds that Mr. Darwin's book in no essential respect contradicts the 'Vestiges'; "on the contrary, while adding to its explanations of nature, it expresses substantially the same general ideas."[195] It is right to say that the passage thus objected to is not to be found in later editions of the 'Origin of Species,' while in the historical sketch we now read as follows:--"In my opinion it (the 'Vestiges of Creation') has done excellent service in this country by calling attention to the subject, removing prejudice, and in thus preparing the ground for the reception of analogous views." Mr. Darwin, the main part of whose work on the 'Origin of Species' is taken up with supporting the theory of descent with modification (which frequently in the recapitulation chapter of the 'Origin of Species' he seems to treat as synonymous with natural selection), has fallen into the common error of thinking that Lamarck can be ignored or passed over in a couple of sentences. I only find Lamarck's name twice in the 1859 edition of the 'Origin,' once on p. 242, where Mr. Darwin writes: "I am surprised that no one has advanced this demonstrative case of neuter insects, against the well-known doctrine of Lamarck;" and again, p. 427, where Lamarck is stated to have been the first to call attention to the "very important distinction between real affinities and analogical or adaptive resemblances." How far from demonstrative is the particular case which in 1859 Mr. Darwin considered so fatal to "the well-known doctrine of Lamarck"--which should surely, one would have thought, include the doctrine of descent with modification, which Mr. Darwin is himself supporting--I have attempted to show in 'Life and Habit,' but had perhaps better recapitulate briefly here. Mr. Darwin writes: "In the simpler case of neuter insects all of one caste, _which, as I believe, have been rendered different from the fertile males and females through natural selection_...."[196] He thus attributes the sterility and peculiar characteristics, we will say, of the common hive working bees--"neuter insects all of one caste"--to natural selection. Now, nothing is more certain than that these characteristics--sterility, a cavity in the thigh for collecting wax, a proboscis for gathering honey, &c.--are due to the treatment which the eggs laid by the queen bee receive after they have left her body. Take an egg and treat it in a certain way, and it becomes a working bee; treat the same egg in a certain other way, and it becomes a queen. If the bees are in danger of becoming queenless they take eggs which were in the way of being developed into working bees, and change their food and cells, whereon they develop into queens instead. How Mr. Darwin could attribute the neutralization of the working bees--an act which is obviously one of abortion committed by the body politic of the hive on a balance of considerations--to the action of what he calls "natural selection," and how, again, he could suppose that what he was advancing had any but a confirmatory bearing upon Lamarck's position, is incomprehensible, unless the passage in question be taken as a mere slip. That attention has been called to it is plain, for the words "the well-known doctrine of Lamarck" have been changed in later editions into "the well-known doctrine of inherited habit as advanced by Lamarck,"[197] but this correction, though some apparent improvement on the original text, does little indeed in comparison with what is wanted. Mr. Darwin has since introduced a paragraph concerning Lamarck into the "historical sketch," already more than once referred to in these pages. In this he summarises the theory which I am about to lay before the reader, by saying that Lamarck "upheld the doctrine that all species, including man, are descended from other species." If Lamarck had been alive he would probably have preferred to see Mr. Darwin write that he upheld "the doctrine of descent with modification as the explanation of all differentiations of structure and instinct." Mr. Darwin continues, that Lamarck "seems" to have been chiefly led to his conclusion on the gradual change of species, "by the difficulty of distinguishing species and varieties, by the almost perfect gradation of forms in certain groups, and by the analogy of domestic productions." Lamarck would probably have said that though he did indeed turn--as Mr. Darwin has done, and as Buffon and Dr. Darwin had done before him--to animals and plants under domestication, in illustration and support of the theory of descent with modification; and that though he did also insist, as so many other writers have done, on the arbitrary and artificial nature of the distinction between species and varieties, he was mainly led to agree with Buffon and Dr. Darwin by a broad survey of the animal kingdom, with the details also of which few naturalists have ever been better acquainted. "Great," says Mr. Darwin, "is the power of steady misrepresentation,"--and greatly indeed has the just fame of Lamarck been eclipsed in consequence; "but," as Mr. Darwin finely continues, "the history of science shows that fortunately this power does not long endure."[198] That Lamarck anticipated it, was prepared to face it, and even felt that things were thus, after all, as they should be, will appear from the shrewd and pleasant passage which is to be found near the close of his preface:-- "So great is the power of preconceived opinion, especially when any personal interest is enlisted on the same side as itself, that though it is hard to deduce new truths from the study of nature, it is still harder to get them recognized by other people. "These difficulties, however, are on the whole more beneficial than hurtful to the cause of science; for it is through them that a number of eccentric, though perhaps plausible speculations, perish in their infancy, and are never again heard of. Sometimes, indeed, valuable ideas are thus lost; but it is better that a truth, when once caught sight of, should have to struggle for a long time without meeting the attention it deserves, than that every outcome of a heated imagination should be readily received. "The more I reflect upon the numerous causes which affect our judgments, the more convinced I am that, with the exception of such physical and moral facts as no one can now throw doubt upon, all else is matter of opinion and argument; and we know well that there is hardly an argument to be found anywhere, against which another argument cannot plausibly be adduced. Hence, though it is plain that the various opinions of men differ greatly in probability and in the weight which should be attached to them, it seems to me that we are wrong when we blame those who differ from us. "Are we then to recognize no opinions as well founded but those which are generally received? Nay--experience teaches us plainly that the highest and most cultivated minds must be at all times in an exceedingly small minority. No one can dispute this. Authority should be told by weight and not by number--but in good truth authority is a hard thing to weigh. "Nor again--in spite of the many and severe conditions which a judgment must fulfil before it can be declared good--is it quite certain that those whom public opinion has declared to be authorities, are always right in the conclusions they arrive at. "Positive facts are the only solid ground for man; the deductions he draws from them are a very different matter. Outside the facts of nature all is a question of probabilities, and the most that can be said is that some conclusions are more probable than others." Lamarck's poverty was perhaps one main reason of the ease with which it was found possible to neglect his philosophical opinions. Science is not a kingdom into which a poor man can enter easily, if he happens to differ from a philosopher who gives good dinners, and has "his sisters and his cousins and his aunts" to play the part of chorus to him. Lamarck's two daughters do not appear to have been the kind of persons who could make effective sisters or cousins or aunts. Men of science are of like passions even with the other holy ones who have set themselves up in all ages as the pastors and prophets of mankind. The saint has commonly deemed it to be for the interests of saintliness that he should strain a point or two in his own favour--and the more so according as his reputation for an appearance of candour has been the better earned. If, then, Lamarck's opponents could keep choruses, while Lamarck had nothing to fall back upon but the merits of his case only, it is not surprising that he should have found himself neglected by the scientists of his own time. Moreover he was too old to have undertaken such an unequal contest. If he had been twenty years younger when he began it, he would probably have enjoyed his full measure of success before he died. Not that Lamarck can claim, as a thinker, to stand on the same level with Dr. Darwin, and still less so with Buffon. He attempted to go too fast and too far. Seeing that if we accept descent with modification, the question arises whether what we call life and consciousness may not themselves be evolved from some thing or things which looked at one time so little living and conscious that we call them inanimate--and being anxious to see his theory reach, and to follow it, as far back as possible, he speculates about the origin of life; having formed a theory thereon, he is more inclined to interpret the phenomena of lower animal life so as to make them fit in with his theory, than as he would have interpreted them if there had been no theory at stake. Thus his denial that sensation, and much more, intelligence and deliberate action, can exist without a brain and a nervous system, has led him to deny sensation, consciousness, and intelligence to many animals which act in such manner as would certainly have made him say that they feel and know what they are about, if he had formed no theory about brains and nervous systems. Nothing can be more different than the manners in which Lamarck and Dr. Darwin wrote on this head. Lamarck over and over again maintains that where there is no nervous system there can be no sensation. Combating, for example, the assertion of Cabanis, that to live is to feel, he says that "the greater number of the polypi and all the infusoria, having no nervous system, it must be said of them as also of worms, that to live is still not to feel; and so again of plants."[199] How different from this is the un-theory-ridden language of Dr. Darwin, quoted on p. 116 of this work. Lamarck again writes:-- "The very imperfect animals of the lowest classes, having no nervous system, are simply irritable, have nothing but certain habits, experience no sensations, and never conceive ideas." This, in the face of the performances of the amoeba--a minute jelly speck, without any special organ whatever--in making its tests, cannot be admitted. Is it possible that Lamarck was in some measure misled by believing Buffon to be in earnest when he advanced propositions little less monstrous? "But," continues Lamarck, "the less imperfect animals which have a nervous system, though they have not the organ of intelligence, have instinct, habits, and proclivities; they feel sensations, and yet form no ideas whatever. I venture to say that where there is no organ for a faculty that faculty cannot exist."[200] Who can tell what ideas a worm does or does not form? We can watch its actions, and see that they are such as involve what we call design and a perception of its own interest. Under these circumstances it seems better to call the worm a reasonable creature with Dr. Darwin than to say with Lamarck that because worms do not appear to have that organ which he assumes to be the sole means of causing sensation and ideas, therefore they can neither feel nor think. Doubtless they cannot feel and think as many sensations and thoughts as we can, but our ideas of what they can and cannot feel must be formed through consideration of what we see them do, and must be biassed by no theories of what they ought to be able to feel or not feel. Again Lamarck, shortly after an excellent passage in which he points out that the lower animals gain by experience just as man does (and here probably he had in his mind the passage of Buffon referred to at p. 112 of this work), nevertheless writes:-- "If the facts and considerations put forward in this volume be held worthy of attention, it will follow necessarily that there are some animals which have neither reason nor instinct" (I should be glad to see one of these animals and to watch its movements), "such as those which have no power of feeling; that there are others which have instinct but no degree whatever of reason" (whereas from Dr. Darwin's premises it should follow, and would doubtless be readily admitted by him, that instinct is reason, but reason many times repeated made perfect, and finally repeated by rote; so that far from being prior to reason, as Lamarck here implies, it can only come long afterwards), "such as those which have a system enabling them to feel, but which still lack the organ of intelligence; and finally, that there are those which have not only instinct, but over and above this a certain degree of reasoning power, such as those creatures which have one system for sensations and another for acts involving intelligence. Instinct is with these last animals the motive power of almost all their actions, and they rarely use what little reason they have. Man, who comes next above them, is also possessed of instincts which inspire some of his actions, but he can acquire much reason, and can use it so as to direct the greater part of his actions."[201] All this will be felt to be less satisfactory than the simple directness of Dr. Darwin. It comes in great measure from following Buffon without being _en rapport_ with him. On the other hand, Lamarck must be admitted to have elaborated the theory of "descent with modification" with no less clearness than Dr. Darwin, and with much greater fulness of detail. There is no substantial difference between the points they wish to establish; Dr. Darwin has the advantage in that not content with maintaining that there will be a power of adaptation to the conditions of an animal's existence which will determine its organism, he goes on to say what the principal conditions are, and shows more lucidly than Lamarck has done (though Lamarck adopts the same three causes in a passage which will follow), that struggle, and consequently modification, will be chiefly conversant about the means of subsistence, of reproduction, and of self-protection. Nevertheless, though Dr. Darwin has said enough to show that he had the whole thing clearly before him, and could have elaborated it as finely as or better than Lamarck himself has done, if he had been so minded, yet the palm must be given to Lamarck on the score of what he actually did, and this I observe to be the verdict of history, for whereas Lamarck's name is still daily quoted, Dr. Darwin's is seldom mentioned, and never with the applause which it deserves. The resemblance between the two writers--that is to say, the complete coincidence of their views--is so remarkable that the question is forced upon us how far Lamarck knew the substance of Dr. Darwin's theory. Lamarck knew Buffon personally; he had been tutor to Buffon's son, and Buffon had three of Lamarck's volumes on the French Flora printed at the royal printing press;--how can we account for Lamarck's having had Buffon's theory of descent with modification before him for so many years, and yet remaining a partisan of immutability till 1801? Before this year we find no trace of his having accepted evolution; thenceforward he is one of the most ardent and constant exponents which this doctrine has ever had. What was it that repelled him in Buffon's system? How is it that in the 'Philosophie Zoologique' there is not, so far as I can remember, a single reference to Buffon, from whom, however, as we shall see, many paragraphs are taken with but very little alteration? I am inclined to think that the secret of this sudden conversion must be found in a French translation by M. Deleuze of Dr. Darwin's poem, 'The Loves of the Plants' which appeared in 1800. Lamarck--the most eminent botanist of his time--was sure to have heard of and seen this, and would probably know the translator, who would be able to give him a fair idea of the 'Zoonomia.' I will give a few of the passages which Lamarck would find in this translation. Speaking of Dr. Darwin, M. Deleuze says:--"Il falloit encore qu'un nouvel observateur, entrant dans la route qui venoit de s'ouvrir, s'y frayât des sentiers ignorés; que liant la physique végétale à la botanique il nous montrât dans les plantes, non seulement des corps organisés soumis à des lois constantes, mais des êtres doués sinon de sensibilité, au moins d'une irritabilité particulière, d'un principe de vie _qui leur fait exécuter des mouvements analogues à leurs besoins_....[202] "Il est des animaux et des plantes qui par le laps du tems paroissent avoir éprouvé des changemens dans leur organisation, _pour s'accommoder à de nouveaux genres de nourriture et aux moyens de se la procurer_. Peut-être les productions de la nature font elles des progrès vers la perfection. Cette idée appuyée par les observations modernes sur l'accroissement progressif des parties solides du globe, s'accorde avec la dignité et la providence du créateur de l'univers."[203] "La nature semble s'être fait un jeu d'établir entre tous les êtres organisés une sorte de guerre qui entretient leur activité: si elle a donné aux uns des moyens de défense, elle a donné aux autres des moyens d'attaque."[204] Turning to the 'Botanic Garden' itself, I find that this admirable sentence belongs to M. Deleuze, and not to Dr. Darwin, who, however, has said what comes to much the same thing,[205] as may be seen p. 227 of this volume. But the authorship is immaterial; whether the passage was by Dr. Darwin or M. Deleuze, it was, in all probability, known to Lamarck before his change of front. * * * * * The note on Trapa Natans again[206] suggests itself as the source from which the passage in the 'Philosophie Zoologique' about the Ranunculus aquatilis is taken,[207] while one of the most important passages in the work, a summary, in fact, of the principal means of modification, seems to be taken, the first half of it from Buffon, and the second from Dr. Darwin. I have called attention to it on pp. 300, 301. We may then suppose that Lamarck failed to understand Buffon, and conceived that he ought either to have gone much farther, or not so far; not being yet prepared to go the whole length himself, he opposed mutability till Dr. Darwin's additions to Buffon's ostensible theory reached him, whereon he at once adopted them, and having received nothing but a few notes and hints, felt himself at liberty to work the theory out independently and claim it. In so original a work as the '_Philosophie Zoologique_' must always be considered, this may be legitimate, but I find in it, as Isidore Geoffroy seems also to have found, a little more claim to complete independence than is acceptable to one who is fresh from Buffon and Dr. Darwin. FOOTNOTES: [186] 'Hist. Nat. Gén.,' tom. ii. p. 404, 1859. [187] 'Système des Animaux sans Vertèbres,' Paris, in-8, an. ix. (1801); 'Discours d'Ouverture,' p. 12, &c.; 'Recherches sur l'Organisation des Corps Vivants,' Paris, in-8, 1802, p. 50, &c.; 'Discours d'Ouverture d'un Cours de Zoologie pour l'an ix.,' Paris, in-8, 1803. This discourse is entirely devoted to the consideration of the question, "What is Species?" [188] 'Discours d'Ouverture d'un Cours de Zoologie,' 1806, Paris, in-8, p. 8, &c. [189] See following chapter. [190] 'Hist, des Anim. sans Vertèb.,' tom, i., Introduction, 1^re ed., 1815; 'Syst. des Conn. Positives,' Paris, in-8, 1820, 1^re part, 2^me sect. ch. ii. p. 114, &c. [191] 'Hist. Nat. Gén.,' tom. ii. p. 407. [192] 'History of Creation,' English translation, vol. i. pp. 111, 112. [193] M. Martins' edition of the 'Philosophie Zoologique,' Paris, 1873. Introd., p. vi. [194] 'Origin of Species,' p. 3, 1859. [195] 'Vestiges of Creation,' ed. 1860, Proofs, Illustrations, &c., p. lxiv. [196] 'Origin of Species,' ed. 1, p. 239; ed. 6, p. 231. [197] 'Origin of Species,' ed. 1, p. 242; ed. 6, 1876, p. 233. [198] 'Origin of Species,' p. 421, ed. 1876. [199] 'Phil. Zool.,' vol. i. p. 404. [200] Ibid. vol. ii. p. 324. [201] 'Phil. Zool.,' vol. ii. p. 410. [202] 'Les Amours des Plantes,' Discours Prélim., p. 7. Paris, 1800. [203] Ibid., Notes du chant i., p. 202. [204] Ibid. p. 238. [205] 'Zoonomia,' vol. i. p. 507. [206] 'Les Amours des Plantes,' p. 360. [207] Vol. i. p. 231, ed. M. Martins, 1873. CHAPTER XVII. SUMMARY OF THE 'PHILOSOPHIE ZOOLOGIQUE.' The first part of the '_Philosophie Zoologique_' is the one which deals with the doctrine of evolution or descent with modification. It is to this, therefore, that our attention will be confined. Yet only a comparatively small part of the three hundred and fifty pages which constitute Lamarck's first part are devoted to setting forth the reasons which led him to arrive at his conclusions--the greater part of the volume being occupied with the classification of animals, which we may again omit, as foreign to our purpose. I shall condense whenever I can, but I do not think the reader will find that I have left out much that bears upon the argument. I shall also use inverted commas while translating with such freedom as to omit several lines together, where I can do so without suppressing anything essential to the elucidation of Lamarck's meaning. I shall, however, throughout refer the reader to the page of the original work from which I am translating. "The common origin of bodily and mental phenomena," says Lamarck in his preliminary chapter, "has been obscured, because we have studied them chiefly in man, who, as the most highly developed of living beings, presents the problem in its most difficult and complicated aspect. If we had begun our study with that of the lowest organisms, and had proceeded from these to the more complex ones, we should have seen the progression which is observable in organization, and the successive acquisition of various special organs, with new faculties for every additional organ. We should thus have seen that sense of needs--originally hardly perceptible, but gradually increasing in intensity and variety--has led to the attempt to gratify them; that the actions thus induced, having become habitual and energetic, have occasioned the development of organs adapted for their performance; that the force which excites organic movements can in the case of the lowest animals exist outside them and yet animate them; that this force was subsequently introduced into the animals themselves, and fixed within them; and, lastly, that it gave rise to sensibility and, in the end, to intelligence."[208] The reader had better be on his guard here, and whenever Lamarck is speculating about the lowest forms of action and sensation. I have thought it well, however, to give enough of these speculations, as occasion arises, to show their tendency. "Sensation is not the proximate cause of organic movements. It may be so with the higher animals, but it cannot be shown to be so with plants, nor even with all known animals. At the outset of life there was none of that sensation which could only arise where organic beings had already attained a considerable development. Nature has done all by slow gradations, both organs and faculties being the outcome of a progressive development.[209] "The mere composition of an animal is but a small part of what deserves study in connection with the animal itself. The effects of its surroundings in causing new wants, the effects of its wants in giving rise to actions, those of its actions in developing habits and tendencies, the effects of use and disuse as affecting any organ, the means which nature takes to preserve and make perfect what has been already acquired--these are all matters of the highest importance.[210] "In their bearing upon these questions the invertebrate animals are more important and interesting than the vertebrate, for they are more in number, and being more in number are more varied; their variations are more marked, and the steps by which they have advanced in complexity are more easily observed.[211] "I propose, therefore, to divide this work into three parts, of which the first shall deal with the conventions necessary for the treatment of the subject, the importance of analogical structures, and the meaning which should be attached to the word species. I will point out on the one hand the evidence of a graduated descending scale, as existing between the highest and the lowest organisms; and, on the other, the effect of surroundings and habits on the organs of living beings, as the cause of their development or arrest of development. Lastly, I will treat of the natural order of animals, and show what should be their fittest classification and arrangement."[212] It seems unnecessary to give Lamarck's intentions with regard to his second and third parts, as they do not here concern us; they deal with the origin of life and mind. The first chapter of the work opens with the importance of bearing in mind the difference between the conventional and the natural, that is to say, between words and things. Here, as indeed largely throughout this part of his work, he follows Buffon, by whom he is evidently influenced. "The conventional deals with systems of arrangement, classification, orders, families, genera, and the nomenclature, whether of different sections or of individual objects. "An arrangement should be called systematic, or arbitrary, when it does not conform to the genealogical order taken by nature in the development of the things arranged, and when, by consequence it is not founded upon well-considered analogies. There is such a thing as a natural order in every department of nature; it is the order in which its several component items have been successively developed.[213] "Some lines certainly seem to have been drawn by Nature herself. It was hard to believe that mammals, for example, and birds, were not well-defined classes. Nevertheless the sharpness of definition was an illusion, and due only to our limited knowledge. The ornithorhynchus and the echidna bridge the gulf.[214] "Simplicity is the main end of any classification. If all the races, or as they are called, species, of any kingdom were perfectly known, and if the true analogies between each species, and between the groups which species form, were also known, so that their approximations to each other and the position of the several groups were in conformity with the natural analogies between them--then classes, orders, sections, and genera would be families, larger or smaller; for each division would be a greater or smaller section of a natural order or sequence.[215] But in this case it would be very difficult to assign the limits of each division; they would be continually subjected to arbitrary alteration, and agreement would only exist where plain and palpable gaps were manifest in our series. Happily, however, for classifiers there are, and will always probably remain, a number of unknown forms."[216] That the foregoing is still felt to be true by those who accept evolution, may be seen from the following passage, taken from Mr. Darwin's 'Origin of Species':-- "As all the organic beings which have ever lived can be arranged within a few great classes; and as all within each class have, according to our theory, been connected together by fine gradations, the best, and if our collections were nearly perfect, the only possible arrangement would be genealogical: descent being the hidden bond of connection which naturalists have been seeking under the term of the Natural System. On this view, we can understand how it is that in the eyes of most naturalists, the structure of the embryo is even more important for classifications than that of the adult."[217] In his second chapter Lamarck deals with the importance of comparative anatomy, and the study of homologous structures. These indicate a sort of blood relationship between the individuals in which they are found, and are our safest guide to any natural system of classification. Their importance is not confined to the study of classes, families, or even species; they must be studied also in the individuals of each species, as it is thus only, that we can recognize either identity or difference of species. The results arrived at, however, are only trustworthy over a limited period, for though the individuals of any species commonly so resemble one another at any given time, as to enable us to generalize from them, at the date of our observing them, yet species are not fixed and immutable through all time: they change, though with such extreme slowness that we do not observe their doing so, and when we come upon a species that _has_ changed, we consider it as a new one, and as having always been such as we now see it.[218] "It is none the less true that when we compare the same kind of organs in different individuals, we can quickly and easily tell whether they are very like each other or not, and hence, whether the animals or plants in which they are found, should be set down as members of the same or of a different species. It is only therefore the general inference drawn from the apparent immutability of species, that has been too inconsiderately drawn.[219] "The analogies and points of agreement between living organisms, are always incomplete when based upon the consideration of any single organ only. But though still incomplete, they will be much more important according as the organ on which they are founded is an essential one or otherwise. "With animals, those analogies are most important which exist between organs most necessary for the conservation of their life. With plants, between their organs of generation. Hence, with animals, it will be the interior structure which will determine the most important analogies: with plants it will be the manner in which they fructify.[220] "With animals we should look to nerves, organs of respiration, and those of the circulation; with plants, to the embryo and its accessories, the sexual organs of their flowers, &c.[221] To do this, will set us on to the Natural Method, which is as it were a sketch traced by man of the order taken by Nature in her productions.[222] Nevertheless the divisions which we shall be obliged to establish, will still be arbitrary and artificial, though presenting to our view sections arranged in the order which Nature has pursued.[223] "What, then," he asks,[224] "_is_ species--and can we show that species has changed--however slowly?" He now covers some of the ground since enlarged upon in Mr. Darwin's second chapter, in which the arbitrary nature of the distinction between species and varieties is so well exposed. "I shall show," says Lamarck (in substance, but I am compelled to condense much), "that the habits by which we now recognize any species, are due to the conditions of life [_circonstances_] under which it has for a long time existed, and that these habits have had such an influence upon the structure of each individual of the species, as to have at length modified this structure, and adapted it to the habits which have been contracted.[225] "The individuals of any species," he continues, "certainly resemble their parents; it is a universal law of nature that all offspring should differ but little from its immediate progenitors, but this does not justify the ordinary belief that species never vary. Indeed, naturalists themselves are in continual difficulty as regards distinguishing species from varieties; they do not recognize the fact that species are only constant as long as the conditions in which they are placed are constant. Individuals vary and form breeds which blend so insensibly into the neighbouring species, that the distinctions made by naturalists between species and varieties, are for the most part arbitrary, and the confusion upon this head is becoming day by day more serious.[226] "Not perceiving that species will not vary as long as the conditions in which they are placed remain essentially unchanged, naturalists have supposed that each species was due to a special act of creation on the part of the Supreme Author of all things. Assuredly, nothing can exist but by the will of this Supreme Author, but can we venture to assign rules to him in the execution of his will? May not his infinite power have chosen to create an order of things which should evolve in succession all that we know as well as all that we do not know? Whether we regard species as created or evolved, the boundlessness of his power remains unchanged, and incapable of any diminution whatsoever. Let us then confine ourselves simply to observing the facts around us, and if we find any clue to the path taken by Nature, let us say fearlessly that it has pleased her Almighty Author that she should take this path.[227] "What applies to species applies also to genera; the further our knowledge extends, the more difficult do we find it to assign its exact limits to any genus. Gaps in our collections are being continually filled up, to the effacement of our dividing lines of demarcation. We are thus compelled to settle the limits of species and variety arbitrarily, and in a manner about which there will be constant disagreement. Naturalists are daily classifying new species which blend into one another so insensibly that there can hardly be found words to express the minute differences between them. The gaps that exist are simply due to our not having yet found the connecting species. "I do not, however, mean to say that animal life forms a simple and continuously blended series. Life is rather comparable to a ramification. In life we should see, as it were, a ramified continuity, if certain species had not been lost. The species which, according to this illustration, stands at the extremity of each bough, should bear a resemblance, at least upon one side, to the other neighbouring species; and this certainly is what we observe in nature. "Having arranged living forms in such an order as this, let us take one, and then, passing over several boughs, let us take another at some distance from it; a wide difference will now be seen between the species which the forms selected represent. Our earliest collections supplied us with such distantly allied forms only; now, however, that we have such an infinitely greater number of specimens, we can see that many of them blend one into the other without presenting noteworthy differences at any step."[228] This has been well extended by Mr. Darwin in a passage which begins:--"The affinities of all beings of the same class have sometimes been represented by a great tree. I believe that this simile largely speaks the truth."[229] "What, then," continues Lamarck, "can be the cause of all this? Surely the following: namely, that when individuals of any species change their situation, climate, mode of existence, or habits [conditions of life], their structure, form, organization, and in fact their whole being becomes little by little modified, till in the course of time it responds to the changes experienced by the creature."[230] In his preface Lamarck had already declared that "the thread which gives us a clue to the causes of the various phenomena of animal organization, in the manifold diversity of its developments, is to be found in the fact that Nature conserves in offspring all that their life and environments has developed in parents." Heredity--"the hidden bond of common descent"--tempered with the modifications induced by changed habits--which changed habits are due to new conditions and surroundings--this with Lamarck, as with Buffon and Dr. Darwin, is the explanation of the diversity of forms which we observe in nature. He now goes on to support this--briefly, in accordance with his design--but with sufficient detail to prevent all possibility of mistake about his meaning. "In the same climate differences in situation, and a greater or less degree of exposure, affect simply, in the first instance, the individuals exposed to them; but in the course of time, these repeated differences of surroundings in individuals which reproduce themselves continually under similar circumstances, induce differences which become part of their very nature; so that after many successive generations, these individuals, which were originally, we will say, of any given species, become transformed into a different one."[231] "Let us suppose that a grass growing in a low-lying meadow gets carried by some accident to the brow of a neighbouring hill, where the soil is still damp enough for the plant to be able to exist. Let it live here for many generations, till it has become thoroughly accustomed to its position, and let it then gradually find its way to the dry and almost arid soil of a mountain side; if the plant is able to stand the change and to perpetuate itself for many generations, it will have become so changed that botanists will class it as a new species."[232] "The same sort of process goes on in the animal kingdom, but animals are modified more slowly than plants."[233] The sterility of hybrids, to which Mr. Darwin devotes a great part of the ninth chapter of his 'Origin of Species,'[234] is then touched on--briefly, but sufficiently--as follows:-- "The idea that species were fixed and immutable involved the belief that distinct species could not be fertile _inter se_. But unfortunately observation has proved, and daily proves, that this supposition is unfounded. Hybrids are very common among plants, and quite sufficiently so among animals to show that the boundaries of these so-called immutable species are not so well defined as has been supposed. Often, indeed, there is no offspring between the individuals of what are called distinct species, especially when they are widely different, and again, the offspring when produced is generally sterile; but when there is less difference between the parents, both the difficulty of breeding the hybrid, and its sterility when produced, are found to disappear. In this very power of crossing we see a source from which breeds, and ultimately species, may arise."[235] Mr. Darwin arrives at the same conclusion. He writes:-- "We must, therefore, either give up the belief of the universal sterility of species when crossed, or we must look at this sterility in animals, not as an indelible characteristic, but as one capable of being removed by domestication. "Finally, on considering all the ascertained facts on the intercrossing of plants and animals, it may be concluded that some degree of sterility, both in first crosses and in hybrids, is an exceedingly general result, but that it cannot, under our present state of knowledge, be considered as absolutely universal."[236] Returning to Lamarck, we find him saying:-- "The limits, therefore, of so-called species are not so constant and unvarying as is commonly supposed. Consider also the following. All living forms upon the face of the globe have been brought forth in the course of infinite time by the process of generation only. Nature has directly created none but the lowest organisms; these she is still producing every day, they being, as it were, the first sketches of life, and produced by what is called spontaneous generation. Organs have been gradually developed in these low forms, and these organs have in the course of time increased in diversity and complexity. The power of growth in each living body has given rise to various modes of reproduction, and thus progress, already acquired, has been preserved and handed down to offspring.[237] With sufficient time, favourable conditions of life [_circonstances_], successive changes in the surface of the globe, and the power of new surroundings and habits to modify the organs of living bodies, all animal and vegetable forms have been imperceptibly rendered such as we now see them. It follows that species will be constant only in relation to their environments, and cannot be as old as Nature herself. "But what are we to say of instinct? Can we suppose that all the tricks, cunning, artifices, precautions, patience, and skill of animals are due to evolution only? Must we not see here the design of an all-powerful Creator? No one certainly will assign limits to the Creator's power, but it is a bold thing to say that he did not choose to work in this way or that way, when his own handiwork declares to us that this is the way he chose. I find proof in Nature--meaning by nature the _ensemble_ of all that is,[238] but regarding her as herself the effect of an unknown first cause[239]--that she is the author of organization, life, and even sensation; that she has multiplied and diversified the organs and mental powers of the creatures which she sustains and reproduces; that she has developed in animals, through the sole instrumentality of sense of need as establishing and directing their habits, all actions and all habits, from the simplest up to those which constitute instinct, industry, and finally reason.[240] "Against this it is alleged that we have no reason to believe species to have changed within any known era. The skeletons of some Egyptian birds, preserved two or three thousand years ago, differ in no particular from the same kind of creatures at the present day. But this is what we should expect, inasmuch as the position and climate of Egypt itself do not appear to have changed. If the conditions of life have not varied, why should the species subjected to those conditions have done so? Moreover, birds can move about freely, and if one place does not suit them they can find another that does. All that these Egyptian mummies really prove is, that there were animals in Egypt two or three thousand years ago which are like the animals of to-day; but how short a space is two or three thousand years, as compared with the time which Nature has had at her disposal! A time infinitely great _quâ_ man, is still infinitely short _quâ_ Nature.[241] "If, however, we turn to animals under confinement, we find immediate proof that the most startling changes are capable of being produced after some generations of changed habits. In the sixth chapter we shall have occasion to observe the power of changed conditions [_circonstances_] to develop new desires in animals, and to induce new courses of action; we shall see the power which these new actions will have, after a certain amount of repetition, to engender new habits and tendencies; and we shall also note the effects of use and disuse in either fortifying and developing an organ, or in diminishing it and causing it to disappear. With plants under domestication, we shall find corresponding phenomena. Species will thus appear to be unchangeable for comparatively short periods only."[242] It is interesting to see that Mr. Darwin lays no less stress on the study of animals and plants under domestication than Buffon, Dr. Darwin, and Lamarck. Indeed, all four writers appear to have been in great measure led to their conclusions by this very study. "At the commencement of my investigations," writes Mr. Darwin, "it seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this obscure problem. Nor have I been disappointed; in this and in all other perplexing cases, I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the best and safest clue. I may venture to express my conviction of the high value of such studies, though they have been very commonly neglected by naturalists."[243] In justice to the three writers whom I have named, it should be borne in mind that they also ventured to express their conviction of the high value of these studies. Buffon, indeed, as we have seen, gives animals under domestication the foremost place in his work. He does not treat of wild animals till he has said all he has to say upon our most important domesticated breeds,--on whose descent from one or two wild stocks he is never weary of insisting. It was doubtless because of the opportunities they afforded him for demonstrating the plasticity of living organism that the most important position in his work was assigned to them. Lamarck professes himself unable to make up his mind about extinct species; how far, that is to say, whole breeds must be considered as having died out, or how far the difference between so many now living and fossil forms is due to the fact that our living species are modified descendants of the fossil ones. Such large parts of the globe were still practically unknown in Lamarck's time, and the recent discovery of the ornithorhynchus has raised such hopes as to what might yet be found in Australia, that he was inclined to think that only such creatures as man found hurtful to him, as, for example, the megatherium and the mastodon, had become truly extinct, nor was he, it would seem, without a hope that these would yet one day be discovered. The climatic and geological changes that have occurred in past ages, would, he believed, account for all the difference which we observe between living and fossil forms, inasmuch as they would have changed the conditions under which animals lived, and therefore their habits and organs would have become correspondingly modified. He therefore rather wondered to find so much, than so little, resemblance between existing and fossil forms. Buffon took a juster view of this matter; it will be remembered that he concluded his remarks upon the mammoth by saying that many species had doubtless disappeared without leaving any living descendants, while others had left descendants which had become modified. Lamarck anticipated Lyell in supposing geological changes to have been due almost entirely to the continued operation of the causes which we observe daily at work in nature: thus he writes:-- "Every observer knows that the surface of the earth has changed; every valley has been exalted, the crooked has been made straight, and the rough places plain; not even is climate itself stable. Hence changed conditions; and these involve changed needs and habits of life; if such changes can give rise to modifications or developments, it is clear that every living body must vary, especially in its outward character, though the variation can only be perceptible after several generations. "It is not surprising then that so few living species should be represented in the geologic record. It is surprising rather that we should find any living species represented at all.[244] "Catastrophes have indeed been supposed, and they are an easy way of getting out of the difficulty; but unfortunately, they are not supported by evidence. Local catastrophes have undoubtedly occurred, as earthquakes and volcanic eruptions, of which the effects can be sufficiently seen; but why suppose any universal catastrophe, when the ordinary progress of nature suffices to account for the phenomena? Nature is never _brusque_. She proceeds slowly step by step, and this with occasional local catastrophes will remove all our difficulties."[245] In his fourth chapter Lamarck points out that animals move themselves, or parts of themselves, not through impulsion or movement communicated to them as from one billiard ball to another, but by reason of a cause which excites their irritability, which cause is within some animals and forms part of them, while it is wholly outside of others.[246] I should again warn the reader to be on his guard against the opinion that any animals can be said to live if they have no "inward motion" of their own which prompts them to act. We cannot call anything alive which moves only as wind and water may make it move, but without any impulse from within to execute the smallest action and without any capacity of feeling. Such a creature does not look sufficiently like the other things which we call alive; it should be first shown to us, so that we may make up our minds whether the facts concerning it have been truly stated, and if so, what it most resembles; we may then classify it accordingly. "Some animals change their place by creeping, some by walking, some by running or leaping; others again fly, while others live in the water and swim. "The origin of these different kinds of locomotion is to be found in the two great wants of animal life: 1, the means of procuring food; 2, the search after mates with a view to reproduction. "Since then the power of locomotion was a matter affecting their individual self-preservation, as well as that of their race, the existence of the want led to the means of its being gratified."[247] Lamarck is practically at one with Dr. Erasmus Darwin, that modification will commonly travel along three main lines which spring from the need of reproduction, of procuring food, and (Dr. Darwin has added) the power of self-protection; but Dr. Darwin's treatment of this part of his subject is more lucid and satisfactory than Lamarck's, inasmuch as he immediately brings forward instances of various modifications which have in each case been due to one of the three main desires above specified, namely, reproduction, subsistence, and self-defence. Lamarck concludes the chapter with some passages which show that he was alive--as what Frenchman could fail to be after Buffon had written?--to the consequences which must follow from the geometrical ratio of increase, and to the struggle for existence, with consequent survival of the fittest, which must always be one of the conditions of any wild animal's existence. The paragraphs, indeed, on this subject are taken with very little alteration from Buffon's work. As Lamarck's theory is based upon the fact that it is on the nature of these conditions that the habits and consequently the structure of any animal will depend, he must have seen that the shape of many of its organs must vary greatly in correlation to the conditions to which it was subjected in the matter of self-protection. I do not see, then, that there is any substantial difference between the positions taken by Dr. Erasmus Darwin and by Lamarck in this respect. "Let us conclude," he writes, "by showing the means employed by nature to prevent the number of her creatures from injuring the conservation of what has been produced already, and of the general order which should subsist.[248] . . . . . . "In consequence of the extremely rapid rate of increase of the smaller, and especially of the most imperfect, animals, their numbers would become so great as to prove injurious to the conservation of breeds, and to the progress already made towards more perfect organization, unless nature had taken precautions to keep them down within certain fixed limits which she cannot exceed."[249] This seems to contain, and in a nutshell, as much of the essence of what Mr. Herbert Spencer and Mr. Charles Darwin have termed the survival of the fittest in the struggle for existence, as was necessary for Lamarck's purpose. To Lamarck, as to Dr. Darwin and Buffon, it was perfectly clear that the facts, that animals have to find their food under varying circumstances, and that they must defend themselves in all manner of varying ways against other creatures which would eat them if they could, were simply some of the conditions of their existence. In saying that the surrounding circumstances--which amount to the conditions of existence--determined the direction in which any plant or animal should be slowly modified, Lamarck includes as a matter of course the fact that the "stronger and better armed should eat the weaker," and thus survive and bear offspring which would inherit the strength and better armour of its parents. Nothing therefore can be more at variance with the truth than to represent Lamarck and the other early evolutionists as ignoring the struggle for existence and the survival of the fittest; these are inevitably implied whenever they use the word "_circonstances_" or environment, as I will more fully show later on, and are also expressly called attention to by the greater number of them.[250] "Animals, except those which are herbivorous, prey upon one another; and the herbivorous are exposed to the attacks of the flesh-eating races. "_The strongest and best armed for attack eat the weaker_, and the greater kinds eat the smaller. Individuals of the same race rarely eat one another; they war only with other races than their own."[251] Dr. Darwin here again has the advantage over Lamarck; for he has pointed out how the males contend with one another for the possession of the females, which I do not find Lamarck to have done, though he would at once have admitted the fact. Lamarck continues:-- "The smaller kinds of animals breed so numerously and so rapidly that they would people the globe to the exclusion of other forms of life, if nature had not limited their inconceivable multitude. As, however, they are the prey of a number of other creatures, live but a short time, and perish easily with cold, they are kept always within the proportions necessary for the maintenance both of their own and of other races.[252] "As regards the larger and stronger animals, they would become dominant, and be injurious to the conservation of many other races, if they could multiply in too great numbers. But as it is, they devour one another, and breed but slowly, and few at a birth, so that equilibrium is duly preserved among them. Man alone is the unquestionably dominant animal, but men war among themselves, so that it may be safely said the world will never be peopled to its utmost capacity."[253] In his fifth chapter Lamarck returns to the then existing arrangement and classification of animals. "Naturalists having remarked that many species, and some genera and even families present characters which as it were isolate them, it has been imagined that these approached or drew further from each other according as their points of agreement or difference seemed greater or less when set down as it were on a chart or map. They regard the small well-marked series which have been styled natural families, as groups which should be placed between the isolated species and their nearest neighbours so as to form a kind of reticulation. This idea, which some of our modern naturalists have held to be admirable, is evidently mistaken, and will be discarded on a profounder and more extended knowledge of organization, and more especially when the distinction has been duly drawn between what is due to the action of special conditions and to general advance of organization."[254] I take it that Lamarck is here attempting to express what Mr. Charles Darwin has rendered much more clearly in the following excellent passage:-- "It should always be borne in mind what sort of intermediate forms must, on the theory [what theory?], have formerly existed. I have found it difficult when looking at any two species to avoid picturing to myself forms _directly_ intermediate between them. But this is a wholly false view; we should always look for forms intermediate between each species and a common but unknown progenitor; and the progenitor will generally have differed in some respects from all its modified descendants. To give a simple illustration: the fantail and pouter pigeons are both descended from the rock pigeon. If we possessed all the intermediate varieties which have ever existed, we should have an extremely close series, between both and the rock pigeon; but we should have no varieties directly intermediate between the fantail and the pouter; none, for instance, combining a tail somewhat expanded with a crop somewhat enlarged, the characteristic features of these two breeds. These two breeds, moreover, have become so much modified that, if we had no historical or indirect evidence regarding their origin, it would not have been possible to have determined, from a mere comparison of their structure with that of the rock pigeon C. livia, whether they had descended from this species, or from some other allied form, as C. oenas. "So with natural species, if we look to forms very distinct--for instance, to the horse and the tapir--we have no reason to suppose that links directly intermediate between them ever existed, but between each and an unknown common parent. The common parent will have had in its whole organization much general resemblance to the tapir and the horse; but in some points of structure it may have differed considerably from both, even perhaps more than they differ from each other. Hence in all such cases we should be unable to recognize the parent form of any two or more species, even if we closely compared the structure of the parent with that of its modified descendants, unless at the same time we had a nearly perfect chain of the intermediate links. . . . . . . "By the theory of natural selection [surely this is a slip for "by the theory of descent with modification"] all living species have been connected with the parent species of each genus, by differences not greater than we see between the natural and domestic varieties of the same species at the present day; and their parent species, now generally extinct, have in their turn been similarly connected with more ancient forms, and so on backwards, always converging to the common ancestor of each great class; so that the number of intermediate and transitional links between all living and extinct species must have been inconceivably great. But assuredly if this theory [the theory of descent with modification or that of "natural selection"?] be true, such have lived upon the earth."[255] To return, however, to Lamarck. "Though Nature," he continues, "in the course of long time has evolved all animals and plants in a true scale of progression, the steps of this scale can be perceived only in the principal groups of living forms; it cannot be perceived in species nor even in genera. The reason of this lies in the extreme diversity of the surroundings in which each different race of animals and plants has existed. These surroundings have often been out of harmony with the growing organization of the plants and animals themselves; this has led to anomalies, and, as it were, digressions, which the mere development of organization by itself could not have occasioned."[256] Or, in other words, to that divergency of type which is so well insisted on by Mr. Charles Darwin. "It is only therefore the principal groups of animal and vegetable life which can be arranged in a vertical line of descent; species and even genera cannot always be so--for these contain beings whose organization has been dependent on the possession of such and such a special system of essential organs. "Each great and separate group has its own system of essential organs, and it is these systems which can be seen to descend, within the limits of the group, from their most complex to their simplest form. But each organ, considered individually, does not descend by equally regular gradation; the gradations are less and less regular according as the organ is of less importance, and is more susceptible of modification by the conditions which surround it. Organs of small importance, and not essential to existence, are not always either perfected or degraded at an equal rate, so that in observing all the species of any class we find an organ in one species in the highest degree of perfection, while another organ, which in this same species is impoverished or very imperfect, is highly developed in another species of the same group."[257] The facts maintained in the preceding paragraph are in great measure supported by Mr. Charles Darwin, who, however, assigns their cause to natural selection. Mr. Darwin writes, "Ordinary specific characters are more variable than generic;" and again, a little lower down, "The points in which all the species of a genus resemble each other, and in which they differ from allied genera, are called generic characters; and these characters may be attributed to inheritance from a common progenitor, for it can rarely happen that natural selection will have modified several distinct species fitted to more or less widely different habits, in exactly the same manner; and as these so called generic characters have been inherited from before the period when the several species first branched off from their common progenitor, and subsequently have not varied or come to differ in any degree, or only in a slight degree, it is not probable that they should vary at the present day. On the other hand, the points in which species differ from other species of the same genus are called specific characters; and as these specific characters have varied and come to differ since the period when the species branched off from a common progenitor, it is probable that they should still often be in some degree variable, or at least more variable than those parts of the organization which have for a very long time remained constant."[258] The fact, then, that it is specific characters which vary most is agreed upon by both Lamarck and Mr. Darwin. Lamarck, however, maintains that it is these specific characters which are most capable of being affected by the habits of the creature, and that it is for this reason they will be most variable, while Mr. Darwin simply says they _are_ most variable, and that, this being so, the favourable variations will be preserved and accumulated--an assertion which Lamarck would certainly not demur to. "Irregular degrees of perfection," says Lamarck, "and degradation in the less essential organs, are due to the fact that these are more liable than the more essential ones to the influence of external circumstances: these induce corresponding differences in the more outward parts of the animal, and give rise to such considerable and singular difference in species, that instead of being able to arrange them in a direct line of descent, as we can arrange the main groups, these species often form lateral ramifications round about the main groups to which they belong, and in their extreme development are truly isolated."[259] In his summary of the second chapter of his 'Origin of Species,' Mr. Darwin well confirms this when he says, "In large genera the species are apt to be closely, but unequally, allied together, forming little clusters round other species." "A longer time," says Lamarck, "and a greater influence of surrounding conditions, is necessary in order to modify interior organs. Nevertheless we see that Nature does pass from one system to another without any sudden leap, when circumstances require it, provided the systems are not too far apart. Her method is to proceed from the more simple to the more complex.[260] "She does this not only in the race, but in the individual." Here Lamarck, like Dr. Erasmus Darwin, shows his perception of the importance of embryology in throwing light on the affinities of animals--as since more fully insisted on by the author of the 'Vestiges of Creation,' and by Mr. Darwin,[261] as well as by other writers. "Breathing through gills is nearer to breathing through lungs than breathing through trachea is. Not only do we see Nature pass from gills to lungs in families which are not too far apart, as may be seen by considering the case of fishes and reptiles; but she does so during the existence of a single individual, which may successively make use both of the one and of the other system. The frog while yet a tadpole breathes through gills; on becoming a frog it breathes through lungs; but we cannot find that Nature in any case passes from trachea to lungs."[262] Lamarck now rapidly reviews previous classifications, and propounds his own, which stands thus:--I. Vertebrata, consisting of Mammals, Birds, Fishes, and Reptiles. II. Invertebrata, consisting of Molluscs, Centipedes, Annelids, Crustacea, Arachnids, Insects, Worms, Radiata, Polyps, Infusoria. "The degradation of organism," he concludes, "in this descending scale is not perfectly even, and cannot be made so by any classification, nevertheless there is such evidence of sustained degradation in the principal groups as must point in the direction of some underlying general principle."[263] Lamarck's sixth chapter is headed "Degradation and Simplification of the Animal Chain as we proceed downwards from the most complex to the most simple Organisms." "This is a positive fact, and results from the operation of a constant law of nature; but a disturbing cause, which can be easily recognized, varies the regular operation of the law from one end to the other of the chain of life.[264] "We can see, nevertheless, that special organs become more and more simple the lower we descend; that they become changed, impoverished, and attenuated little by little; that they lose their local centres, and finally become definitely annihilated before we reach the lowest extremity of the chain.[265] "As has been said already, the degradation of organism is not always regular; such and such an organ often fails or changes suddenly, and sometimes in its changes assumes forms which are not allied with any others by steps that we can recognize. An organ may disappear and reappear several times before being entirely lost: but this is what we might expect, for the cause which has led to the evolution of living organisms has evolved many varieties, due to external influences. Nevertheless, looking at organization broadly, we observe a descending scale."[266] "If the tendency to progressive development was the only cause which had influenced the forms and organs of animals, development would have been regular throughout the animal chain; but it has not been so: Nature is compelled to submit her productions to an environment which acts upon them, and variation in environment will induce variation in organism: this is the true cause of the sometimes strange deviations from the direct line of progression which we shall have to observe.[267] "If Nature had only called aquatic beings into existence, and if these beings had lived always in the same climate, in the same kind of water, and at the same depth, the organization of these animals would doubtless have presented an even and regular scale of development. But there has been fresh water, salt water, running and stagnant water, warm and cold climates, an infinite variety of depth: animals exposed to these and other differences in their surroundings have varied in accordance with them.[268] In like manner those animals which have been gradually fitted for living in air instead of water have been subjected to an endless diversity in their surroundings. The following law, then, may be now propounded, namely:-- "_That anomalies in the development of organism are due to the influences of the environment and to the habits of the creature._[269] "Some have said that the anomalies above mentioned are so great as to disprove the existence of any scale which should indicate descent; but the nearer we approach species, the smaller we see differences become, till with species itself we find them at times almost imperceptible."[270] Lamarck here devotes about seventy pages to a survey of the animal kingdom in its entirety, beginning with the mammals and ending with the infusoria. He points out the manner in which organ after organ disappears as we descend the scale, till we are left with a form which, though presenting all the characteristics of life, has yet no special organ whatever. I am obliged to pass this classification over, but do so very unwillingly, for it is illustrative of Lamarck, both at his best and at his worst. The seventh chapter is headed-- "On the influence of their surroundings on the actions and habits of animals, and on the effect of these habits and actions in modifying their organization." "The effect of different conditions of our organization upon our character, tendencies, actions, and even our ideas, has been often remarked, but no attention has yet been paid to that of our actions and habits upon our organization itself. These actions and habits depend entirely upon our relations to the surroundings in which we habitually exist; we shall have occasion, therefore, to see how great is the effect of environment upon organization. "But for our having domesticated plants and animals we should never have arrived at the perception of this truth; for though the influence of the environment is at all times and everywhere active upon all living bodies, its effects are so gradual that they can only be perceived over long periods of time.[271] "Taking the chain of life in the inverse order of nature--that is to say, from man downwards--we certainly perceive a sustained but irregular degradation of organism, with an increasing simplicity both in organism and faculties. "This fact should throw light upon the order taken by nature, but it does not show us why the gradation is so irregular, nor why throughout its extent we find so many anomalies or digressions which have apparently no order at all in their manifold varieties.[272] The explanation of this must be sought for in the infinite diversity of circumstances under which organisms have been developed. On the one hand, there is a tendency to a regular progressive development; on the other, there is a host of widely different surroundings which tend continually to destroy the regularity of development. "It is necessary to explain what is meant by such expressions as 'the effect of its environment upon the form and organization of an animal.' It must not be supposed that its surroundings directly effect any modification whatever in the form and organization of an animal.[273] Great changes in surroundings involve great changes in the wants of animals, and these changes in their wants involve corresponding changes in their actions. If these new wants become permanent, or of very long duration, the animals contract new habits, which last as long as the wants which gave rise to them.[274] A great change in surroundings, if it persist for a long time, must plainly, therefore, involve the contraction of new habits. These new habits in their turn involve a preference for the employment of such and such an organ over such and such another organ, and in certain cases the total disuse of an organ which is no longer wanted. This is perfectly self-evident.[275] "On the one hand, new wants have rendered a part necessary, which part has accordingly been created by a succession of efforts: use has kept it in existence, gradually strengthening and developing it till in the end it attains a considerable degree of perfection. On the other, new circumstances having in some cases rendered such or such a part useless, disuse has led to its gradually ceasing to receive the development which the other parts attain to; on this it becomes reduced, and in time disappears.[276] "Plants have neither actions nor habits properly so called, nevertheless they change in a changed environment as much as animals do. This is due to changes in nutrition, absorption and transpiration, to degrees of heat, light, and moisture, and to the preponderance over others which certain of the vital functions attain to." Lamarck is led into the statement that plants have neither actions nor habits, by his theories about the nervous system and the brain. Plain matter-of-fact people will prefer the view taken by Buffon, Dr. Darwin, and, more recently, by Mr. Francis Darwin, that there is no radical difference between plants and animals. "The differences between well-nourished and ill-nourished plants become little by little very noticeable. If individuals, whether animal or vegetable, are continually ill-fed and exposed to hardships for several generations, their organization becomes eventually modified, and the modification is transmitted until a race is formed which is quite distinct from those descendants of the common parent stock which have been placed in favourable circumstances.[277] In a dry spring the meagre and stunted herbage seeds early. When, on the other hand, the spring is warm but with occasional days of rain, there is an excellent hay-crop. If, however, any cause perpetuates unfavourable circumstances, plants will vary correspondingly, first in appearance and general conditions, and then in several particulars of their actual character, certain organs having received more development than others, these differences will in the course of time become hereditary.[278] "Nature changes a plant or animal's surroundings gradually--man sometimes does so suddenly. All botanists know that plants vary so greatly under domestication that in time they become hardly recognizable. They undergo so much change that botanists do not at all like describing domesticated varieties. Wheat itself is an example. Where can wheat be found as a wild plant, unless it have escaped from some neighbouring cultivation? Where are our cauliflowers, our lettuces, to be found wild, with the same characters as they possess in our kitchen gardens? "The same applies to our domesticated breeds of animals. What a variety of breeds has not man produced among fowls and pigeons, of which we can find no undomesticated examples!"[279] The foregoing remarks on the effects of domestication seem to have been inspired by those given p. 123 and pp. 168, 169 of this volume.[280] "Some, doubtless, have changed less than others, owing to their having undergone a less protracted domestication, and a less degree of change in climate; nevertheless, though our ducks and geese, for example, are of the same type as their wild progenitors, they have lost the power of long and sustained flight, and have become in other respects considerably modified.[281] "A bird, after having been kept five or six years in a cage, cannot on being liberated fly like its brethren which have been always free. Such a change in a single lifetime has not effected any transmissible modification of type; but captivity, continued during many successive generations, would undoubtedly do so. If to the effects of captivity there be added also those of changed climate, changed food, and changed actions for the purpose of laying hold of food, these, united together and become constant, would in the course of time develop an entirely new breed." This, again, is almost identical with the passage from Buffon,[282] p. 148 of this volume. See also pp. 169, 170. "Where can our many domestic breeds of dogs be found in a wild state? Where are our bulldogs, greyhounds, spaniels, and lapdogs, breeds presenting differences which, in wild animals, would be certainly called specific? These are all descended from an animal nearly allied to the wolf, if not from the wolf itself. Such an animal was domesticated by early man, taken at successive intervals into widely different climates, trained to different habits, carried by man in his migrations as a precious capital into the most distant countries, and crossed from time to time with other breeds which had been developed in similar ways. Hence our present multiform breeds."[283] Here, also, it is impossible to forget Buffon's passages on the dog, given pp. 121, 122. See also p. 223. "Observe the gradations which are found between the _ranunculus aquatilis_ and the _ranunculus hederaceus_: the latter--a land plant--resembles those parts of the former which grow above the surface of the water, but not those that grow beneath it.[284] "The modifications of animals arise more slowly than those of plants; they are therefore less easily watched, and less easily assignable to their true causes, but they arise none the less surely. As regards these causes, the most potent is diversity of the surroundings in which they exist, but there are also many others.[285] "The climate of the same place changes, and the place itself changes with changed climate and exposure, but so slowly that we imagine all lands to be stable in their conditions. This, however, is not true; climatic and other changes induce corresponding changes in environment and habit, and these modify the structure of the living forms which are subjected to them. Indeed, we see intermediate forms and species corresponding to intermediate conditions. "To the above causes must be ascribed the infinite variety of existing forms, independently of any tendency towards progressive development."[286] The reader has now before him a fair sample of "the well-known doctrine of inherited habit as advanced by Lamarck."[287] In what way, let me ask in passing, does "the case of neuter insects" prove "demonstrative" against it, unless it is held equally demonstrative against Mr. Darwin's own position? Lamarck continues:-- "The character of any habitable quarter of the globe is _quâ_ man constant: the constancy of type in species is therefore also _quâ_ man persistent. But this is an illusion. We establish, therefore, the three following propositions:-- "1. That every considerable and sustained change in the surroundings of any animal involves a real change in its needs. "2. That such change of needs involves the necessity of changed action in order to satisfy these needs, and, in consequence, of new habits.[288] "3. It follows that such and such parts, formerly less used, are now more frequently employed, and in consequence become more highly developed; new parts also become insensibly evolved in the creature by its own efforts from within. "From the foregoing these two general laws may be deduced:-- "_Firstly. That in every animal which has not passed its limit of development, the more frequent and sustained employment of any organ develops and aggrandizes it, giving it a power proportionate to the duration of its employment, while the same organ in default of constant use becomes insensibly weakened and deteriorated, decreasing imperceptibly in power until it finally disappears._[289] "_Secondly. That these gains or losses of organic development, due to use or disuse, are transmitted to offspring, provided they have been common to both sexes, or to the animals from which the offspring have descended._"[290] Lamarck now sets himself to establish the fact that animals have developed modifications which have been transmitted to their offspring. "Naturalists," he says, "have believed that the possession of certain organs has led to their employment. This is not so: it is need and use which have developed the organs, and even called them into existence." [I have already sufficiently insisted that it is impossible to dispense with either of these two views. Demand and Supply have gone hand in hand, each reacting upon the other.] "Otherwise a special act of creation would be necessary for every different combination of conditions; and it would be also necessary that the conditions should remain always constant. "If this were really so we should have no racehorses like those of England, nor drayhorses so heavy in build and so unlike the racehorse; for there are no such breeds in a wild state. For the same reason, we should have no turnspit dogs with crooked legs, no greyhounds nor water-spaniels; we should have no tailless breed of fowls nor fantail pigeons, &c. Nor should we be able to cultivate wild plants in our gardens, for any length of time we please, without fear of their changing. "'Habit,' says the proverb, 'is a second nature'; what possible meaning can this proverb have, if descent with modification is unfounded?[291] "As regards the circumstances which give rise to variation, the principal are climatic changes, different temperatures of any of a creature's environments, differences of abode, of habit, of the most frequent actions; and lastly, of the means of obtaining food, self-defence, reproduction, &c., &c."[292] Here we have absolute agreement with Dr. Erasmus Darwin,[293] except that there seems a tendency in this passage to assign more effect to the direct action of conditions than is common with Lamarck. He seems to be mixing Buffon and Dr. Darwin. "In consequence of change in any of these respects, the faculties of an animal become extended and enlarged by use: they become diversified through the long continuance of the new habits, until little by little their whole structure and nature, as well as the organs originally affected, participate in the effects of all these influences, and are modified to an extent which is capable of transmission to offspring."[294] This sentence alone would be sufficient to show that Lamarck was as much alive as Buffon and Dr. Darwin were before him, to the fact that one of the most important conditions of an animal's life, is the relation in which it stands to the other inhabitants of the same neighbourhood--from which the survival of the fittest follows as a self-evident proposition. Nothing, therefore, can be more unfounded than the attempt, so frequently made by writers who have not read Lamarck, or who think others may be trusted not to do so, to represent him as maintaining something perfectly different from what is maintained by modern writers on evolution. The difference, in so far as there is any difference, is one of detail only. Lamarck would not have hesitated to admit, that, if animals are modified in a direction which is favourable to them, they will have a better chance of surviving and transmitting their favourable modifications. In like manner, our modern evolutionists should allow that animals are modified not because they subsequently survive, but because they have done this or that which has led to their modification, and hence to their surviving. Having established that animals and plants are capable of being materially changed in the course of a few generations, Lamarck proceeds to show that their modification is due to changed distribution of the use and disuse of their organs at any given time. "_The disuse of an organ_," he writes, "_if it becomes constant in consequence of new habits, gradually reduces the organ, and leads finally to its disappearance_."[295] "Thus whales have lost their teeth, though teeth are still found in the embryo. So, again, M. Geoffroy has discovered in birds the groove where teeth were formerly placed. The ant-eater, which belongs to a genus that has long relinquished the habit of masticating its food, is as toothless as the whale."[296] Then are adduced further examples of rudimentary organs, which will be given in another place, and need not be repeated here. Speaking of the fact, however, that serpents have no legs, though they are higher in the scale of life than the batrachians, Lamarck attributes this "to the continued habit of trying to squeeze through very narrow places, where four feet would be in the way, and would be very little good to them, inasmuch as more than four would be wanted in order to turn bodies that were already so much elongated."[297] If it be asked why, on Lamarck's theory, if serpents wanted more legs they could not have made them, the answer is that the attempt to do this would be to unsettle a question which had been already so long settled, that it would be impossible to reopen it. The animal must adapt itself to four legs, or must get rid of all or some of them if it does not like them; but it has stood so long committed to the theory that if there are to be legs at all, there are to be not more than four, that it is impossible for it now to see this matter in any other light. The experiments of M. Brown Séquard on guinea pigs, quoted by Mr. Darwin,[298] suggest that the form of the serpent may be due to its having lost its legs by successive accidents in squeezing through narrow places, and that the wounds having been followed by disease, the creature may have bitten the limbs off, in which case the loss might have been very readily transmitted to offspring; the animal would accordingly take to a sinuous mode of progression that would doubtless in time elongate the body still further. M. Brown Séquard "carefully recorded" thirteen cases, and saw even a greater number, in which the loss of toes by guinea pigs which had gnawed their own toes off, was immediately transmitted to offspring. Accidents followed by disease seem to have been somewhat overlooked as a possible means of modification. The missing forefinger to the hand of the potto[299] would appear at first sight to have been lost by some such mishap. Returning to Lamarck, we find him saying:-- "Even in the lifetime of a single individual we can see organic changes in consequence of changed habits. Thus M. Tenon has constantly found the intestinal canal of drunkards to be greatly shorter than that of people who do not drink. This is due to the fact that habitual drunkards eat but little solid food, so that the stomach and intestines are more rarely distended. The same applies to people who lead studious and sedentary lives. The stomachs of such persons and of drunkards have little power, and a small quantity will fill them, while those of men who take plenty of exercise remain in full vigour and are even increased."[300] It becomes now necessary to establish the converse proposition, namely that:-- "_The frequent use of an organ increases its power; it even develops the organ itself, and makes it acquire dimensions and powers which it is not found to have in animals which make no use of such an organ._ "In support of this we see that the bird whose needs lead it to the water, in which to find its prey, extends the toes of its feet when it wants to strike the water, and move itself upon the surface. The skin at the base of the toes of such a bird contracts the habit of extending itself from continual practice. To this cause, in the course of time, must be attributed the wide membrane which unites the toes of ducks, geese, &c. The same efforts to swim, that is to say, to push the water for the purpose of moving itself forward, has extended the membrane between the toes of frogs, turtles, the otter, and the beaver."[301] [This is taken, I believe, from Dr. Darwin or Buffon, but I have lost the passage, if, indeed, I ever found it. It had been met by Paley some years earlier (1802) in the following:-- "There is nothing in the action of swimming as carried on by a bird upon the surface of the water that should generate a membrane between the toes. As to that membrane it is an action of constant resistance.... The web feet of amphibious quadrupeds, seals, otters, &c., fall under the same observation."[302]] "On the other hand those birds whose habits lead them to perch on trees, and which have sprung from parents that have long contracted this habit, have their toes shaped in a perfectly different manner. Their claws become lengthened, sharpened, and curved, so as to enable the creature to lay hold of the boughs on which it so often rests. The shore bird again, which does not like to swim, is nevertheless continually obliged to enter the water when searching after its prey. Not liking to plunge its body in the water, it makes every endeavour to extend and lengthen its lower limbs. In the course of long time these birds have come to be elevated, as it were, on stilts, and have got long legs bare of feathers as far as their thighs, and often still higher. The same bird is continually trying to extend its neck in order to fish without wetting its body, and in the course of time its neck has become modified accordingly.[303] "Swans, indeed, and geese have short legs and very long necks, but this is because they plunge their heads as low in the water as they can in their search for aquatic larvæ and other animalcules, but make no effort to lengthen their legs."[304] This too is taken from some passage which I have either never seen or have lost sight of. Paley never gives a reference to an opponent, though he frequently does so when quoting an author on his own side, but I can hardly doubt that he had in his mind the passage from which Lamarck in 1809 derived the foregoing, when in 1802 he wrote § 5 of chapter xv. and the latter half of chapter xxiii. of his 'Natural Theology.' "The tongues of the ant-eater and the woodpecker," continues Lamarck, "have become elongated from similar causes. Humming birds catch hold of things with their tongues; serpents and lizards use their tongues to touch and reconnoitre objects in front of them, hence their tongues have come to be forked. "Need--always occasioned by the circumstances in which an animal is placed, and followed by sustained efforts at gratification--can not only modify an organ, that is to say, augment or reduce it, but can change its position when the case requires its removal.[305] "Ocean fishes have occasion to see what is on either side of them, and have their eyes accordingly placed on either side their head. Some fishes, however, have their abode near coasts on submarine banks and inclinations, and are thus forced to flatten themselves as much as possible in order to get as near as they can to the shore. In this situation they receive more light from above than from below, and find it necessary to pay attention to whatever happens to be above them; this need has involved the displacement of their eyes, which now take the remarkable position which we observe in the case of soles, turbots, plaice, &c. The transfer of position is not even yet complete in the case of these fishes, and the eyes are not, therefore, symmetrically placed; but they are so with the skate, whose head and whole body are equally disposed on either side a longitudinal section. Hence the eyes of this fish are placed symmetrically upon the uppermost side.[306] "The eyes of serpents are placed on the sides and upper portions of the head, so that they can easily see what is on one side of them or above them; but they can only see very little in front of them, and supplement this deficiency of power with their tongue, which is very long and supple, and is in many kinds so divided that it can touch more than one object at a time; the habit of reconnoitring objects in front of them with their tongues has even led to their being able to pass it through the end of their nostrils without being obliged to open their jaws.[307] "Herbivorous mammals, such as the elephant, rhinoceros, ox, buffalo, horse, &c., owe their great size to their habit of daily distending themselves with food and taking comparatively little exercise. They employ their feet for standing, walking, or running, but not for climbing trees. Hence the thick horn which covers their toes. These toes have become useless to them, and are now in many cases rudimentary only. Some pachyderms have five toes covered with horn; some four, some three. The ruminants, which appear to be the earliest mammals that confined themselves to a life upon the ground, have but two hooves, while the horse has only one.[308] "Some herbivorous animals, especially among the ruminants, have been incessantly preyed upon by carnivorous animals, against which their only refuge is in flight. Necessity has therefore developed the light and active limbs of antelopes, gazelles, &c. Ruminants, only using their jaws to graze with, have but little power in them, and therefore generally fight with their heads. The males fight frequently with one another, and their desires prompt an access of fluids to the parts of their heads with which they fight; thus the horns and bosses have arisen with which the heads of most of these animals are armed.[309] The giraffe owes its long neck to its continued habit of browsing upon trees, whence also the great length of its fore legs as compared with its hinder ones. Carnivorous animals, in like manner, have had their organs modified in correlation with their desires and habits. Some climb, some scratch in order to burrow in the earth, some tear their prey; they therefore have need of toes, and we find their toes separated and armed with claws. Some of them are great hunters, and also plunge their claws deeply into the bodies of their victims, trying to tear out the part on which they have seized; this habit has developed a size and curvature of claw which would impede them greatly in travelling over stony ground; they have therefore been obliged to make efforts to draw back their too projecting claws, and so, little by little, has arisen the peculiar sheath into which cats, tigers, lions, &c., withdraw their claws when they no longer wish to use them.[310] "We see then that the long-sustained and habitual exercise of any part of a living organism, in consequence of the necessities engendered by its environment, develops such part, and gives it a form which it would never have attained if the exercise had not become an habitual action. All known animals furnish us with examples of this.[311] If anyone maintains that the especially powerful development of any organ has had nothing to do with its habitual use--that use has added nothing, and disuse detracted nothing from its efficiency, but that the organ has always been as we now see it from the creation of the particular species onwards--I would ask why cannot our domesticated ducks fly like wild ducks? I would also quote a multitude of examples of the effects of use and disuse upon our own organs, effects which, if the use and disuse were constant for many generations, would become much more marked. "A great number of facts show, as will be more fully insisted on, that when its will prompts an animal to this or that action, the organs which are to execute it receive an excess of nervous fluid, and this is the determinant cause of the movements necessary for the required action. Modifications acquired in this way eventually become permanent in the breed that has acquired them, and are transmitted to offspring, without the offspring's having itself gone through the processes of acquisition which were necessary in the case of the ancestor.[312] Frequent crosses, however, with unmodified individuals, destroy the effect produced. It is only owing to the isolation of the races of man through geographical and other causes, that man himself presents so many varieties, each with a distinctive character. "A review of all existing classes, orders, genera, and species would show that their structure, organs, and faculties, are in all cases solely attributable to the surroundings to which each creature has been subjected by nature, and to the habits which individuals have been compelled to contract; and that they are not at all the result of a form originally bestowed, which has imposed certain habits upon the creature.[313] "It is unnecessary to multiply instances; the fact is simply this, that all animals have certain habits, and that their organization is always in perfect harmony with these habits.[314] The conclusion hitherto accepted is that the Author of Nature, when he created animals, foresaw all the possible circumstances in which they would be placed, and gave an unchanging organism to each creature, in accordance with its future destiny. The conclusion, on the other hand, here maintained is that nature has evolved all existing forms of life successively, beginning with the simplest organisms and gradually proceeding to those which are more complete. Forms of life have spread themselves throughout all the habitable parts of the earth, and each species has received its habits and corresponding modification of organs, from the influence of the surroundings in which it found itself placed.[315] "The first conclusion supposes an unvarying organism and unvarying conditions. The second, which is my theory (_la mienne propre_), supposes that each animal is capable of modifications which in the course of generations amount to a wide divergence of type. "If a single animal can be shown to have varied considerably under domestication, the first conclusion is proved to be inadmissible, and the second to be in conformity with the laws of nature." This is a milder version of Buffon's conclusion (see _ante_, pp. 90, 91). It is a little grating to read the words "la mienne propre," and to recall no mention of Buffon in the 'Philosophie Zoologique.' "Animal forms then are the result of conditions of life and of the habits engendered thereby. With new forms new faculties are developed, and thus nature has little by little evolved the existing differentiations of animal and vegetable life."[316] Lamarck makes no exception in man's favour to the rule of descent with modification. He supposes that a race of quadrumanous apes gradually acquired the upright position in walking, with a corresponding modification of the feet and facial angle. Such a race having become master of all the other animals, spread itself over all parts of the world that suited it. It hunted out the other higher races which were in a condition to dispute with it for enjoyment of the world's productions, and drove them to take refuge in such places as it did not desire to occupy. It checked the increase of the races nearest itself, and kept them exiled in woods and desert places, so that their further development was arrested, while itself, able to spread in all directions, to multiply without opposition, and to lead a social life, it developed new requirements one after another, which urged it to industrial pursuits, and gradually perfected its capabilities. Eventually this pre-eminent race, having acquired absolute supremacy, came to be widely different from even the most perfect of the lower animals. "Certain apes approach man more nearly than any other animal approaches him; nevertheless, they are far inferior to him, both in bodily and mental capacity. Some of them frequently stand upright, but as they do not habitually maintain this attitude, their organization has not been sufficiently modified to prevent it from being irksome to them to stand for long together. They fall on all fours immediately at the approach of danger. This reveals their true origin.[317] "But is the upright position altogether natural, even to man? He uses it in moving from place to place, but still standing is a fatiguing position, and one which can only be maintained for a limited time, and by the aid of muscular contraction. The vertebrate column does not pass through the axis of the head so as to maintain it in like equilibrium with other limbs. The head, chest, stomach, and intestines weigh almost entirely on the anterior part of the vertebrate column, and this column itself is placed obliquely, so that, as M. Richerand has observed, continual watchfulness and muscular exertion are necessary to avoid the falls towards which the weight and disposition of our parts are continually inclining us. 'Children,' he remarks, 'have a constant tendency to assume the position of quadrupeds.'"[318] "Surely these facts should reveal man's origin as analogous to that of the other mammals, if his organization only be looked to. But the following consideration must be added. New wants, developed in societies which had become numerous, must have correspondingly multiplied the ideas of this dominant race, whose individuals must have therefore gradually felt the need of fuller communication with each other. Hence the necessity for increasing and varying the number of the signs suitable for mutual understanding. It is plain therefore that incessant efforts would be made in this direction.[319] "The lower animals, though often social, have been kept in too great subjection for any such development of power. They continue, therefore, stationary as regards their wants and ideas, very few of which need be communicated from one individual to another. A few movements of the body, a few simple cries and whistles, or inflexions of voice, would suffice for their purpose. With the dominant race, on the other hand, the continued multiplication of ideas which it was desirable to communicate rapidly, would exhaust the power of pantomimic gesture and of all possible inflexions of the voice--therefore by a succession of efforts this race arrived at the utterance of articulate sounds. A few only would be at first made use of, and these would be supplemented by inflexions of the voice: presently they would increase in number, variety, and appropriateness, with the increase of needs and of the efforts made to speak. Habitual exercise would increase the power of the lips and tongue to articulate distinctly. "The diversity of language is due to geographical distribution, with consequent greater or less isolation of certain races, and corruption of the signs originally agreed upon for each idea. Man's own wants, therefore, will have achieved the whole result. They will have given rise to endeavour, and habitual use will have developed the organs of articulation."[320] How, let me ask again, is "the case of neuter insects" "demonstrative" against the "well-known" theory put forward in the foregoing chapter? FOOTNOTES: [208] 'Phil. Zool.,' tom. i., edited by M. Martins, 1873, pp. 25, 26. [209] 'Phil. Zool.' tom. i. pp. 26, 27. [210] Page 28. [211] Pages 28-31. [212] 'Phil. Zool.,' tom. i. pp. 34, 35. [213] Page 42. [214] Page 46. [215] 'Phil. Zool.,' tom. i. p. 50. [216] Pages 50, 51. [217] 'Origin of Species,' p. 395, ed. 1876. [218] 'Phil. Zool.,' tom. i. p. 61. [219] 'Phil. Zool.,' tom. i. p. 62. [220] Page 63. [221] Page 64. [222] Page 65. [223] Page 67. [224] Chap. iii. [225] 'Phil. Zool.,' tom. i. p. 72. [226] Pages 71-73. [227] 'Phil. Zool.,' tom. i. p. 74, 75. [228] 'Phil. Zool.,' tom. i. pp. 75-77. [229] 'Origin of Species,' p. 104, ed. 1876. [230] 'Phil. Zool.,' tom. i. p. 79. [231] 'Phil. Zool.,' tom. i. pp. 79, 80. [232] 'Phil. Zool.,' tom. i. p. 80. [233] Page 80. [234] Ed. 1876. [235] 'Phil. Zool.,' tom. i. p. 81. [236] 'Origin of Species,' p. 241. [237] 'Phil. Zool.,' p. 82. [238] 'Phil. Zool.,' tom. i. p. 83. [239] Pages 349-351. [240] Page 84. [241] 'Phil. Zool.,' tom. i. p. 88. [242] Page 90. [243] 'Origin of Species,' p. 3. [244] 'Phil. Zool.,' tom. i. p. 94. [245] Pages 95-96. [246] Page 97. [247] Phil. Zool.,' tom. i. p. 98. [248] 'Phil. Zool.,' tom. i. p. 111. [249] 'Phil. Zool.,' tom. i. p. 112. [250] See pp. 227 and 259 of this book. [251] 'Phil. Zool.,' tom. i. p. 113. [252] Page 113. [253] 'Phil Zool.,' tom. i. p. 113. [254] This passage is rather obscure. I give it therefore in the original:-- "Ainsi les naturalistes ayant remarqué que beaucoup d'espèces, certains genres, et même quelques familles paraissent dans une sorte d'isolement, quant à leurs caractères, plusieurs se sont imaginés que les êtres vivants, dans l'un ou l'autre règne, s'avoisinaient, ou s'éloignaient entre eux, relativement à leurs _rapports naturels_, dans une disposition semblable aux differents points d'une carte de géographie ou d'une mappemonde. Ils regardent les petites séries bien prononcées qu'on a nommées familles naturelles, comme devant être disposées entre elles de manière à former une réticulation. Cette idée qui a paru sublime à quelques modernes, est évidemment une erreur, et, sans doute, elle se dissipera dès qu'on aura des connaissances plus profondes et plus générales de l'organisation, et surtout lorsqu'on distinguera ce qui appartient à l'influence des lieux d'habitation et des habitudes contractées, de ce qui résulte des progrès plus ou moins avancés dans la composition ou le perfectionnement de l'organisation."--(p. 120). [255] 'Origin of Species,' pp. 265, 266. [256] 'Phil. Zool.,' tom. i. p. 121. [257] 'Phil. Zool.,' tom. i. p. 122. [258] 'Origin of Species,' pp. 122, 123. [259] 'Phil. Zool.,' tom. i. p. 123. [260] 'Phil. Zool.,' tom. i. p. 123. [261] 'Origin of Species,' chap. xiv. [262] 'Phil. Zool.,' tom. i. p. 123. [263] 'Phil. Zool.,' tom. i. p. 140. [264] Page 142. [265] Page 143. [266] 'Phil. Zool.,' tom. i. p. 143. [267] Page 144. [268] Ibid. [269] 'Phil. Zool.,' tom. i. p. 145. [270] Page 146. [271] 'Phil. Zool.,' tom. i. p. 221. [272] Page 222. [273] 'Phil. Zool.,' tom. i. p. 223. [274] Page 224. [275] Page 223. [276] Page 225. [277] 'Phil. Zool.,' tom. i. p. 225. [278] Page 226. [279] 'Phil. Zool.,' tom. i. p. 228. [280] See Buffon, 'Hist. Nat.,' tom. v. pp. 196, 197, and Supp. tom. v. pp. 250-253. [281] 'Phil. Zool.,' tom. i. p. 229. [282] 'Hist. Nat.,' tom. xi. p. 290. [283] 'Phil. Zool.,' tom. i. p. 231. [284] Page 231. See Dr. Darwin's note on _Trapa natans_, 'Botanic Garden,' part ii. canto 4, l. 204. [285] 'Phil. Zool.,' tom. i. p. 232. [286] Page 233. See Buffon on Climate, tom. ix., 'The Animals of the Old and New Worlds.' [287] 'Origin of Species,' p. 233, ed. 1876. [288] 'Phil. Zool.,' tom. i. p 234. [289] Page 235. [290] Page 236. [291] 'Phil. Zool.,' tom. i. p. 237. [292] Page 238. [293] See _ante_, pp. 220-228. [294] 'Phil. Zool.,' tom. i. p. 239. [295] 'Phil. Zool.,' tom. i. p 240. [296] Page 241. [297] Page 245. [298] 'Animals and Plants under Domestication,' vol. i. p. 467, &c. [299] See frontispiece to Professor Mivart's 'Genesis of Species.' [300] 'Phil. Zool.,' tom. i. p. 247. [301] Page 248. [302] 'Nat. Theol.,' vol. xii., end of § viii. [303] 'Phil. Zool.,' tom. i. p. 249. [304] 'Phil. Zool.,' tom. i. p. 250. [305] Page 250. [306] 'Phil. Zool.,' tom. i. p. 251. [307] Page 252. [308] 'Phil. Zool.,' tom. i. p. 253. [309] Page 254. [310] 'Phil. Zool.,' tom. i. p. 256. [311] Page 257. [312] 'Phil. Zool.,' tom. i. p. 259. [313] Page 260. [314] Page 263. [315] 'Phil. Zool.,' tom. i. p. 263. [316] Page 265. [317] 'Phil. Zool.,' tom. i. p. 343. [318] 'Phil. Zool.,' tom. i. p. 343. [319] Page 346. [320] 'Phil. Zool.,' tom. i. p. 347. CHAPTER XVIII. MR. PATRICK MATTHEW, MM. ÉTIENNE AND ISIDORE GEOFFROY ST. HILAIRE, AND MR. HERBERT SPENCER. The same complaint must be made against Mr. Matthew's excellent survey of the theory of evolution, as against Dr. Erasmus Darwin's original exposition of the same theory, namely, that it is too short. It may be very true that brevity is the soul of wit, but the leaders of science will generally succeed in burking new-born wit, unless the brevity of its soul is found compatible with a body of some bulk. Mr. Darwin writes thus concerning Mr. Matthew in the historical sketch to which I have already more than once referred. "In 1831 Mr. Patrick Matthew published his work on 'Naval Timber and Arboriculture,' in which he gives precisely the same view on the origin of species as that (presently to be alluded to) propounded by Mr. Wallace and myself in the 'Linnean Journal,' and as that enlarged in the present volume. Unfortunately the view was given by Mr. Matthew very briefly, in scattered passages in an appendix to a work on a different subject, so that it remained unnoticed until Mr. Matthew himself drew attention to it in the 'Gardener's Chronicle' for April 7, 1860. The differences of Mr. Matthew's view from mine are not of much importance; he seems to consider that the world was nearly depopulated at successive periods, and then re-stocked, and he gives as an alternative, that new forms may be generated 'without the presence of any mould or germ of former aggregates.' I am not sure that I understand some passages; but it seems that he attributes much influence to the direct action of the conditions of life. He clearly saw, however, the full force of the principle of natural selection."[321] Nothing could well be more misleading. If Mr. Matthew's view of the origin of species is "precisely the same as that" propounded by Mr. Darwin, it is hard to see how Mr. Darwin can call those of Lamarck and Dr. Erasmus Darwin "erroneous"; for Mr. Matthew's is nothing but an excellent and well-digested summary of the conclusions arrived at by these two writers and by Buffon. If, again, Mr. Darwin is correct in saying that Mr. Matthew "clearly saw the full force of the principle of natural selection," he condemns the view he has himself taken of it in his 'Origin of Species,' for Mr. Darwin has assigned a far more important and very different effect to the fact that the fittest commonly survive in the struggle for existence, than Mr. Matthew has done. Mr. Matthew sees a cause underlying all variations; he takes the most teleological or purposive view of organism that has been taken by any writer (not a theologian) except myself, while Mr. Darwin's view, if not the least teleological, is certainly nearly so, and his confession of inability to detect any general cause underlying variations, leaves, as will appear presently, less than common room for ambiguity. Here are Mr. Matthew's own words:-- "There is a law universal in nature, tending to render every reproductive being the best possibly suited to the condition that its kind, or that organized matter is susceptible of, and which appears intended to model the physical and mental or instinctive, powers to their highest perfection, and to continue them so. This law sustains the lion in his strength, the hare in her swiftness, and the fox in his wiles. As nature in all her modifications of life has a power of increase far beyond what is needed to supply the place of what falls by Time's decay, those individuals who possess not the requisite strength, swiftness, hardihood, or cunning, fall prematurely without reproducing--either a prey to their natural devourers, or sinking under disease, generally induced by want of nourishment, their place being occupied by the more perfect of their own kind, who are pressing on the means of existence. "Throughout this volume, we have felt considerable inconvenience from the adopted dogmatical classification of plants, and have all along been floundering between species and variety, which certainly under culture soften into each other. A particular conformity, each after its own kind, when in a state of nature, termed species, no doubt exists to a considerable degree. This conformity has existed during the last forty centuries; geologists discover a like particular conformity--fossil species--through the deep deposition of each great epoch; but they also discover an almost complete difference to exist between the species or stamp of life of one epoch from that of every other. We are therefore led to admit either a repeated miraculous conception, or _a power of change under change of circumstances_ to belong to living organized matter, or rather to the congeries of inferior life which appears to form superior." (By this I suppose Mr. Matthew to imply his assent to the theory, that our personality or individuality is but as it were "the consensus, or full flowing river of a vast number of subordinate individualities or personalities, each one of which is a living being with thoughts and wishes of its own.") "The derangements and changes in organized existence, induced by a change of circumstances from the interference of man, afford us proof of the plastic quality of superior life; and the likelihood that circumstances have been very different in the different epochs, though steady in each, tend strongly to heighten the probability of the latter theory. "When we view the immense calcareous and bituminous formations, principally from the waters and atmosphere, and consider the oxidations and depositions which have taken place, either gradually or during some of the great convulsions, it appears at least probable that the liquid elements containing life have varied considerably at different times in composition and weight; that our atmosphere has contained a much greater proportion of carbonic acid or oxygen; and our waters, aided by excess of carbonic acid, and greater heat resulting from greater density of atmosphere, have contained a greater quantity of lime, and other mineral solutions. Is the inference, then, unphilosophic that living things which are proved to have _a circumstance-suiting power_ (a very slight change of circumstance by culture inducing a corresponding change of character), may have gradually accommodated themselves to the variations of the elements containing them, and without new creation, have presented the diverging changeable phenomena of past and present organized existence? "The destructive liquid currents before which the hardest mountains have been swept and comminuted into gravel, sand, and mud, which intervened between and divided these epochs, probably extending over the whole surface of the globe and destroying nearly all living things, must have reduced existence so much that an unoccupied field would be formed for new diverging ramifications of life, which from the connected sexual system of vegetables, and the natural instinct of animals to herd and combine with their own kind, would fall into specific groups--these remnants in the course of time moulding and accommodating their being anew to the change of circumstances, and to every possible means of subsistence--and the millions of ages of regularity which appear to have followed between the epochs, probably after this accommodation was completed, affording fossil deposit of regular specific character. . . . . . . "In endeavouring to trace ... the principle of these changes of fashion which have taken place in the domiciles of life the following questions occur: Do they arise from admixture of species nearly allied producing intermediate species? Are they the diverging ramifications of the living principle under modification of circumstance? or have they resulted from the combined agency of both? "_Is there only one living principle? Does organized existence, and perhaps all material existence, consist of one Proteus principle of life_ capable of gradual circumstance-suited modifications and aggregations without bound, under the solvent or motion-giving principle of heat or light? There is more beauty and unity of design in this continual balancing of life to circumstance, and greater conformity to those dispositions of nature that are manifest to us, than in total destruction and new creation. It is improbable that much of this diversification is owing to commixture of species nearly allied; all change by this appears very limited and confined within the bounds of what is called species; the progeny of the same parents under great difference of circumstance, might in several generations even become distinct species, incapable of co-reproduction. "The self-regulating adaptive disposition of organized life may, in part, be traced to the extreme fecundity of nature, who, as before stated, has in all the varieties of her offspring a prolific power much beyond (in many cases a thousand fold) what is necessary to fill up the vacancies caused by senile decay. As the field of existence is limited and preoccupied, it is only the hardier, more robust, better suited to circumstance individuals, who are able to struggle forward to maturity, these inhabiting only the situations to which they have _superior adaptation and greater power of occupancy than any other kind; the weaker and less circumstance-suited being prematurely destroyed_. This principle is in constant action; it regulates the colour, the figure, the capacities, and instincts; those individuals in each species whose colour and covering are best suited to concealment or protection from enemies, or defence from inclemencies and vicissitudes of climate, whose figure is best accommodated to health, strength, defence, and support; whose capacities and instincts can best regulate the physical energies to self-advantage according to circumstances--in such immense waste of primary and youthful life those only come forward to maturity from the strict ordeal by which nature tests their adaptation to her standard of perfection and fitness to continue their kind by reproduction. "From the unremitting operation of this law acting in concert with the tendency which the progeny have to take the more particular qualities of the parents, together with the connected sexual system in vegetables and instinctive limitation to its own kind in animals, a considerable uniformity of figure, colour, and character is induced constituting species; the breed gradually acquiring the very best possible adaptation of these to its condition which it is susceptible of, and when alteration of circumstance occurs, thus changing in character to suit these, as far as its nature is susceptible of change. "This circumstance-adaptive law operating upon the slight but continued natural disposition to sport in the progeny (seedling variety) _does not preclude the supposed influence which volition or sensation may have had over the configuration of the body_. To examine into the disposition to sport in the progeny, even when there is only one parent as in many vegetables, and to investigate how much variation is modified by the mind or nervous sensation of the parents, or of the living thing itself during its progress to maturity; how far it depends upon external circumstance, and how far on the will, irritability, and muscular exertion, is open to examination and experiment. In the first place, we ought to examine its dependency upon the preceding links of the particular chain of life, variety being often merely types or approximations of former parentage; thence the variation of the family as well as of the individual must be embraced by our experiments. "This continuation of family type, not broken by casual particular aberration, is mental as well as corporeal, and is exemplified in many of the dispositions or instincts of particular races of men. _These innate or continuous ideas or habits seem proportionally greater in the insect tribes, and in those especially of shorter revolution; and forming an abiding memory, may resolve much of the enigma of instinct, and the foreknowledge which these tribes have of what is necessary to completing their round of life, reducing this to knowledge or impressions and habits acquired by a long experience._ "This greater continuity of existence, or rather continuity of perceptions and impressions in insects, is highly probable; _it is even difficult in some to ascertain the particular steps when each individual commences_, under the different phases of egg, larva, pupa, or if much consciousness of individuality exists. The continuation of reproduction for several generations by the females alone in some of these tribes, _tends to the probability of the greater continuity of existence; and the subdivisions of life by cuttings (even in animal life), at any rate, must stagger the advocate of individuality_. "Among the millions of specific varieties of living things which occupy the humid portions of the surface of our planet, as far back as can be traced, there does not appear, with the exception of man, to have been any particular engrossing race, but a pretty fair balance of power of occupancy--or rather most wonderful variation of circumstance parallel to the nature of every species, _as if circumstance and species had grown up together_. There are, indeed, several races which have threatened ascendancy in some particular regions; but it is man alone from whom any general imminent danger to the existence of his brethren is to be dreaded. "As far back as history reaches, man had already had considerable influence, and had made encroachments upon his fellow denizens, probably occasioning the destruction of many species, and the production and continuation of a number of varieties, and even species, which he found more suited to supply his wants, but which from the infirmity of their condition--_not having undergone selection by the law of nature_, of which we have spoken--cannot maintain their ground without culture and protection. "It is only however in the present age that man has begun to reap the fruits of his tedious education, and has proven how much 'knowledge is power.' He has now acquired a dominion over the material world, and a consequent power of increase, so as to render it probable that the whole surface of the earth may soon be overrun by this engrossing anomaly, to the annihilation of every wonderful and beautiful variety of animal existence which does not administer to his wants, principally as laboratories of preparation to befit cruder elemental matter for assimilation by his organs. . . . . . . "The consequences are being now developed of our deplorable ignorance of, or inattention to, one of the most evident traits of natural history--that vegetables, as well as animals, are generally liable to an almost unlimited diversification, regulated by climate, soil, nourishment, and new commixture of already-formed varieties. In those with which man is most intimate, and where his agency in throwing them from their natural locality and disposition has brought out this power of diversification in stronger shades, it has been forced upon his notice, as in man himself, in the dog, horse, cow, sheep, poultry,--in the apple, pear, plum, gooseberry, potato, pea, which sport in infinite varieties, differing considerably in size, colour, taste, firmness of texture, period of growth, almost in every recognizable quality. In all these kinds man is influential in preventing deterioration, by careful selection of the largest or most valuable as breeders."[322] _Étienne and Isidore Geoffroy._ "Both Cuvier and Étienne Geoffroy," says Isidore Geoffroy, "had early perceived the philosophical importance of a question (evolution) which must be admitted as--with that of unity of composition--the greatest in natural history. We find them laying it down in the year 1795 in one of their joint 'Memoirs' (on the Orangs), in the very plainest terms, in the following question, 'Must we see,' they inquire, 'what we commonly call species, as the modified descendants of the same original form?' "Both were at that time doubtful. Some years afterwards Cuvier not only answered this question in the negative, but declared, and pretended to prove, that the same forms have been perpetuated from the beginning of things. Lamarck, his antagonist _par excellence_ on this point, maintained the contrary position with no less distinctness, showing that living beings are unceasingly variable with change of their surroundings, and giving with some boldness a zoological genesis in conformity with this doctrine. "Geoffroy St. Hilaire had long pondered over this difficult subject. The doctrine which in his old age he so firmly defended, does not seem to have been conceived by him till after he had completed his 'Philosophie Anatomique,' and except through lectures delivered orally to the museum and the faculty, it was not published till 1828; nor again in the work then published do we find his theory in its neatest expression and fullest development." Isidore Geoffroy St. Hilaire tells us in a note that the work referred to as first putting his father's views before the public in a printed form, was a report to the Academy of Sciences on a memoir by M. Roulin; but that before this report some indications of them are to be found in a paper on the Gavials, published in 1825. Their best rendering, however, and fullest development is in several memoirs, published in succession, between the years 1828 and 1837. "This doctrine," he continues, "is diametrically opposed to that of Cuvier, and is not entirely the same as Lamarck's. Geoffroy St. Hilaire refutes the one, he restrains and corrects the other. Cuvier, according to him, sums up against the facts, while Lamarck goes further than they will bear him out. Essentially however on questions of this nature he is a follower of Lamarck, and took pleasure on several occasions in describing himself as the disciple of his illustrious _confrère_."[323] I have been unable to detect any substantial difference of opinion between Geoffroy St. Hilaire and Lamarck, except that the first maintained that a line must be drawn somewhere--and did not draw it--while the latter said that no line could be drawn, and therefore drew none. Mr. Darwin is quite correct in saying that Geoffroy St. Hilaire "relied chiefly on the conditions of life, or the 'monde ambiant,' as the cause of change." But this is only Lamarck over again, for though Lamarck attributes variation directly to change of habits in the creature, he is almost wearisome in his insistence on the fact that the habit will not change, unless the conditions of life also do so. With both writers then it is change in the relative positions of the exterior circumstances, and of the organism, which results in variation, and finally in specific modification. Here is another sketch of Étienne Geoffroy, also by his son Isidore. In 1795, while Lamarck was still a believer in immutability, Étienne Geoffroy St. Hilaire "had ventured to say that species might well be 'degenerations from a single type,'" but, though he never lost sight of the question, he waited more than a quarter of a century before passing from meditation to action. "He at length put forward his opinion in 1825, he returned to it, but still briefly, in 1828 and 1829, and did not set himself to develop and establish it till the year 1831--the year following the memorable discussion in the Academy, on the unity of organic composition."[324] "If," says his son, "he began by paying homage to his illustrious precursor, and by laying it down as a general axiom, that there is no such thing as fixity in nature, and especially in animated nature, he follows this adhesion to the general doctrine of variability by a dissent which goes to the very heart of the matter. And this dissent becomes deeper and deeper in his later works. Not only is Geoffroy St. Hilaire at pains to deny the unlimited extension of variability which is the foundation of the Lamarckian system, but he moreover and particularly declines to explain those degenerations which he admits as possible, by changes of action and habit on the part of the creature varying--Lamarck's favourite hypothesis, which he laboured to demonstrate without even succeeding in making it appear probable."[325] Isidore Geoffroy then declares that his father, "though chronologically a follower of Lamarck, should be ranked philosophically as having continued the work of Buffon, to whom all his differences of opinion with Lamarck serve to bring him nearer."[326] If he had understood Buffon he would not have said so. His conclusions are thus summed up:--"Geoffroy St. Hilaire maintains that species are variable if the environment varies in character; differences, then, more or less considerable according to the power of the modifying causes _may have_ been produced in the course of time, and the living forms of to-day _may be_ the descendants of more ancient forms."[327] It is not easy to see that much weight should be attached to Geoffroy St. Hilaire's opinion. He seems to have been a person of hesitating temperament, under an impression that there was an opening just then through which a judicious trimmer might pass himself in among men of greater power. If his son has described his teaching correctly, it amounts practically to a _bonâ fide_ endorsement of what Buffon can only be considered to have pretended to believe. The same objection that must be fatal to the view pretended by Buffon, is so in like manner to those put forward seriously of both the Geoffroys--for Isidore Geoffroy followed his father, but leant a little more openly towards Lamarck. He writes:-- "The characters of species are neither absolutely fixed, as has been maintained by some; nor yet, still more, indefinitely variable as according to others. They are fixed for each species as long as that species continues to reproduce itself in an unchanged environment; but they become modified if the environment changes."[328] This is all that Lamarck himself would expect, as no one could be more fully aware than M. Geoffroy, who, however, admits that degeneration may extend to generic differences.[329] I have been unable to find in M. Isidore Geoffroy's work anything like a refutation of Lamarck's contention that the modifications in animals and plants are due to the needs and wishes of the animals and plants themselves; on the contrary, to some extent he countenances this view himself, for he says, "hence arise notable differences of habitation and climate, and these in their turn induce secondary differences in diet _and even in habits_."[330] From which it must follow, though I cannot find it said expressly, that the author attributes modification in some measure to changed habits, and therefore to the changed desires from which the change of habits has arisen; but in the main he appears to refer modification to the direct action of a changed environment. _Mr. Herbert Spencer._ "Those who cavalierly reject the theory of Lamarck and his followers as not adequately supported by facts," wrote Mr. Herbert Spencer,[331] "seem quite to forget that their own theory is supported by no facts at all"--inasmuch as no one pretends to have seen an act of direct creation. Mr. Spencer points out that, according to the best authorities, there are some 320,000 species of plants now existing, and about 2,000,000 species of animals, including insects, and that if the extinct forms which have successively appeared and disappeared be added to these, there cannot have existed in all less than some ten million species. "Which," asks Mr. Spencer, "is the most rational theory about these ten millions of species? Is it most likely that there have been ten millions of special creations? or, is it most likely that by continual modification _due to change of circumstances_, ten millions of varieties may have been produced as varieties are being produced still?" . . . . . . "Even could the supporters of the development hypothesis merely show that the production of species by the process of modification is conceivable, they would be in a better position than their opponents. But they can do much more than this; they can show that the process of modification has effected and is effecting great changes in all organisms, subject to modifying influences ... they can show that any existing species--animal or vegetable--when placed under conditions different from its previous ones, _immediately begins to undergo certain changes of structure_ fitting it for the new conditions. They can show that in successive generations these changes continue until ultimately the new conditions become the natural ones. They can show that in cultivated plants and domesticated animals, and in the several races of men, these changes have uniformly taken place. They can show that the degrees of difference, so produced, are often, as in dogs, greater than those on which distinctions of species are in other cases founded. They can show that it is a matter of dispute whether some of these modified forms _are_ varieties or modified species. They can show too that the changes daily taking place in ourselves; the facility that attends long practice, and the loss of aptitude that begins when practice ceases; the strengthening of passions habitually gratified, and the weakening of those habitually curbed; the development of every faculty, bodily, moral or intellectual, according to the use made of it, are all explicable on this same principle. And thus they can show that throughout all organic nature there _is_ at work a modifying influence of the kind they assign as the cause of these specific differences, an influence which, though slow in its action, does in time, if the circumstances demand it, produce marked changes; an influence which, to all appearance, would produce in the millions of years, and under the great varieties of condition which geological records imply, any amount of change." This leaves nothing to be desired. It is Buffon, Dr. Darwin, and Lamarck, well expressed. Those were the days before "Natural Selection" had been discharged into the waters of the evolution controversy, like the secretion of a cuttle fish. Changed circumstances immediately induce changed habits, and hence a changed use of some organs, and disuse of others: as a consequence of this, organs and instincts become changed, "and these changes continue in successive generations, until ultimately the new conditions become the natural ones." This is the whole theory of "development," "evolution," or "descent with modification." Volumes may be written to adduce the details which warrant us in accepting it, and to explain the causes which have brought it about, but I fail to see how anything essential can be added to the theory itself, which is here so well supported by Mr. Spencer, and which is exactly as Lamarck left it. All that remains is to have a clear conception of the oneness of personality between parents and offspring, of the eternity, and latency, of memory, and of the unconsciousness with which habitual actions are repeated, which last point, indeed, Mr. Spencer has himself touched upon. Mr. Spencer continues--"That by any series of changes a zoophyte should ever become a mammal, seems to those who are not familiar with zoology, and who have not seen how clear becomes the relationship between the simplest and the most complex forms, when all intermediate forms are examined, a very grotesque notion ... they never realize the fact that by small increments of modification, any amount of modification may in time be generated. That surprise which they feel on finding one whom they last saw as a boy, grown into a man, becomes incredulity when the degree of change is greater. Nevertheless, abundant instances are at hand of the mode in which we may pass to the most diverse forms by insensible gradations." Nothing can be more satisfactory and straightforward. I will make one more quotation from this excellent article:-- "But the blindness of those who think it absurd to suppose that complex organic forms may have arisen by successive modifications out of simple ones, becomes astonishing when we remember that complex organic forms are daily being thus produced. A tree differs from a seed immeasurably in every respect--in bulk, in structure, in colour, in form, in specific gravity, in chemical composition--differs so greatly that no visible resemblance of any kind can be pointed out between them. Yet is the one changed in the course of a few years into the other--changed so gradually that at no moment can it be said, 'Now the seed ceases to be, and the tree exists.' What can be more widely contrasted than a newly-born child, and the small, semi-transparent gelatinous spherule constituting the human ovum? The infant is so complex in structure that a cyclopædia is needed to describe its constituent parts. The germinal vesicle is so simple, that a line will contain all that can be said of it. Nevertheless, a few months suffices to develop the one out of the other, and that too by a series of modifications so small, that were the embryo examined at successive minutes, not even a microscope would disclose any sensible changes. That the uneducated and ill-educated should think the hypothesis that all races of beings, man inclusive, may in process of time have been evolved from the simplest monad a ludicrous one is not to be wondered at. But for the physiologist, who knows that every individual being _is_ so evolved--who knows further that in their earliest condition the germs of all plants and animals whatsoever are so similar, 'that there is no appreciable distinction among them which would enable it to be determined whether a particular molecule is the germ of a conferva or of an oak, of a zoophyte or of a man'[332]--for him to make a difficulty of the matter is inexcusable. Surely, if a single structureless cell may, when subjected to certain influences, become a man in the space of twenty years, there is nothing absurd in the hypothesis that under certain other influences a cell may, in the course of millions of years, give origin to the human race. The two processes are generically the same, and differ only in length and complexity." * * * * * The very important extract from Professor Hering's lecture should perhaps have been placed here. The reader will, however, find it on page 199. FOOTNOTES: [321] 'Origin of Species,' Hist. Sketch, p. xvi. [322] See 'Naval Timber and Arboriculture,' by Patrick Matthew, published by Adam and C. Black, Edinburgh, and Longmans and Co., London, 1831, pp. 364, 365, 381-388, and also 106-108, 'Gardeners' Chronicle,' April 7, 1860. [323] 'Vie et Doctrine Scientifique de Geoffroy Étienne St. Hilaire,' Paris, Strasbourg, 1847, pp. 344-346. [324] 'Hist. Nat. Gén.,' tom. ii. 413. [325] 'Hist. Nat. Gén.,' tom. ii. p. 415. [326] Ibid. [327] Ibid. p. 421. [328] 'Hist. Nat. Gén.,' vol. ii. p. 431, 1859. [329] 'Origin of Species,' Hist. Sketch, p. xix. [330] 'Hist. Nat. Gén.,' vol. ii. p. 432. [331] See 'The Leader,' March 20, 1852, "The Haythorne Papers." [332] Carpenter's 'Principles of Physiology', 3rd ed., p. 867. CHAPTER XIX. MAIN POINTS OF AGREEMENT AND OF DIFFERENCE BETWEEN THE OLD AND NEW THEORIES OF EVOLUTION. Having put before the reader with some fulness the theories of the three writers to whom we owe the older or teleological view of evolution, I will now compare that view more closely with the theory of Mr. Darwin and Mr. Wallace, to whom, in spite of my profound difference of opinion with them on the subject of natural selection, I admit with pleasure that I am under deep obligation. For the sake of brevity, I shall take Lamarck as the exponent of the older view, and Mr. Darwin as that of the one now generally accepted. We have seen, that up to a certain point there is very little difference between Lamarck and Mr. Darwin. Lamarck maintains that animals and plants vary: so does Mr. Darwin. Lamarck maintains that variations having once arisen have a tendency to be transmitted to offspring and accumulated: so does Mr. Darwin. Lamarck maintains that the accumulation of variations, so small, each one of them, that it cannot be, or is not noticed, nevertheless will lead in the course of that almost infinite time during which life has existed upon earth, to very wide differences in form, structure, and instincts: so does Mr. Darwin. Finally, Lamarck declares that all, or nearly all, the differences which we observe between various kinds of animals and plants are due to this exceedingly gradual and imperceptible accumulation, during many successive generations, of variations each one of which was in the outset small: so does Mr. Darwin. But in the above we have a complete statement of the fact of evolution, or descent with modification--wanting nothing, but entire, and incapable of being added to except in detail, and by way of explanation of the causes which have brought the fact about. As regards the general conclusion arrived at, therefore, I am unable to detect any difference of opinion between Lamarck and Mr. Darwin. They are both bent on establishing the theory of evolution in its widest extent. The late Sir Charles Lyell, in his 'Principles of Geology,' bears me out here. In a note to his _résumé_ of the part of the 'Philosophie Zoologique' which bears upon evolution, he writes:-- "I have reprinted in this chapter word for word my abstract of Lamarck's doctrine of transmutation, as drawn up by me in 1832 in the first edition of the 'Principles of Geology.'[333] I have thought it right to do this in justice to Lamarck, in order to show how nearly the opinions taught by him at the commencement of this century resembled those now in vogue amongst a large body of naturalists respecting the infinite variability of species, and the progressive development in past time of the organic world. The reader must bear in mind that when I made this analysis of the 'Philosophie Zoologique' in 1832, I was altogether opposed to the doctrine that the animals and plants now living were the lineal descendants of distinct species, only known to us in a fossil state, and ... so far from exaggerating, I did not do justice to the arguments originally adduced by Lamarck and Geoffroy St. Hilaire, especially those founded on the occurrence of rudimentary organs. There is therefore no room for suspicion that my account of the Lamarckian hypothesis, written by me thirty-five years ago, derived any colouring from my own views tending to bring it more into harmony with the theory since propounded by Darwin."[334] So little difference did Sir Charles Lyell discover between the views of Lamarck and those of his successors. With the identity, however, of the main proposition which, both Lamarck and Mr. Darwin alike endeavour to establish, the points of agreement between the two writers come to an end. Lamarck's great aim was to discover the cause of those variations whose accumulation results in specific, and finally in generic, differences. Not content with establishing the fact of descent with modification, he, like his predecessors, wishes to explain how it was that the fact came about. He finds its explanation in changed surroundings--that is to say, in changed conditions of existence--as the indirect cause, and in the varying needs arising from these changed conditions as the direct cause. According to Lamarck, there is a broad principle which underlies variation generally, and this principle is the power which all living beings possess of slightly varying their actions in accordance with varying needs, coupled with the fact observable throughout nature that use develops, and disuse enfeebles an organ, and that the effects, whether of use or disuse, become hereditary after many generations. This resolves itself into the effect of the mutual interaction of mind on body and of body on mind. Thus he writes:-- "The physical and the mental are to start with undoubtedly one and the same thing; this fact is most easily made apparent through study of the organization of the various orders of known animals. From the common source there proceeded certain effects, and these effects, in the outset hardly separated, have in the course of time become so perfectly distinct, that when looked at in their extremest development they appear to have little or nothing in common. "The effect of the body upon the mind has been already sufficiently recognized; not so that of the mind upon the body itself. The two, one in the outset though they were, interact upon each other more and more the more they present the appearance of having become widely sundered, and it can be shown that each is continually modifying the other and causing it to vary."[335] And again, later:-- "I shall show that the habits by which we now recognize any creature are due to the environment (_circonstances_) under which it has for a long while existed, _and that these habits have had such an influence upon the structure of each individual of the species as to have at length_" (that is to say, through many successive slight variations, each due to habit engendered by the wishes of the animal itself), "modified this structure and adapted it to the habits contracted."[336] These quotations must suffice, for the reader has already had Lamarck's argument sufficiently put before him. Variation, and consequently modification, are, according to Lamarck, the outward and visible signs of the impressions made upon animals and plants in the course of their long and varied history, each organ chronicling a time during which such and such thoughts and actions dominated the creature, and specific changes being the effect of certain long-continued wishes upon the body, and of certain changed surroundings upon the wishes. Plants and animals are living forms of faith, or faiths of form, whichever the reader pleases. Mr. Darwin, on the other hand, repeatedly avows ignorance, and profound ignorance, concerning the causes of those variations which, or nothing, must be the fountain-heads of species. Thus he writes of "the complex and _little known_ laws of variation."[337] "There is also _some probability_ in the view propounded by Andrew Knight, that variability _may be partly_ connected with excess of food."[338] "Many laws regulate variation, _some few of which_ can be _dimly seen_."[339] "The results of the _unknown_, or _but dimly understood_, laws of variation are infinitely complex and diversified."[340] "We are _profoundly ignorant_ of the cause of each slight variation or individual difference."[341] "We are _far too ignorant_ to speculate on the relative importance of the several known and unknown causes of variation."[342] He admits, indeed, the effects of use and disuse to have been important, but how important we have no means of knowing; he also attributes considerable effect to the action of changed conditions of life--but how considerable again we know not; nevertheless, he sees no great principle underlying the variations generally, and tending to make them appear for a length of time together in any definite direction advantageous to the creature itself, but either expressly, as at times, or by implication, as throughout his works, ascribes them to accident or chance. In other words, he admits his ignorance concerning them, and dwells only on the accumulation of variations the appearance of which for any length of time in any given direction he leaves unaccounted for. Lamarck, again, having established his principle that sense of need is the main direct cause of variation, and having also established that the variations thus engendered are inherited, so that divergences accumulate and result in species and genera, is comparatively indifferent to further details. His work is avowedly an outline. Nevertheless, we have seen that he was quite alive to the effects of the geometrical ratio of increase, and of the struggle for existence which thence inevitably follows. Mr. Darwin, on the other hand, comparatively indifferent to, or at any rate silent concerning the causes of those variations which appeared so all-important to Lamarck, inasmuch as they are the raindrops which unite to form the full stream of modification, goes into very full detail upon natural selection, or the survival of the fittest, and maintains it to have been "the most important but not the exclusive means of modification."[343] It will be readily seen that, according to Lamarck, the variations which when accumulated amount to specific and generic differences, will have been due to causes which have been mainly of the same kind for long periods together. Conditions of life change for the most part slowly, steadily, and in a set direction; as in the direction of steady, gradual increase or decrease of cold or moisture; of the steady, gradual increase of such and such an enemy, or decrease of such and such a kind of food; of the gradual upheaval or submergence of such and such a continent, and consequent drying up or encroachment of such and such a sea, and so forth. The thoughts of the creature varying will thus have been turned mainly in one direction for long together; and hence the consequent modifications will also be mainly in fixed and definite directions for many successive generations; as in the direction of a warmer or cooler covering; of a better means of defence or of attack in relation to such and such another species; of a longer neck and longer legs, or of whatever other modification the gradually changing circumstances may be rendering expedient. It is easy to understand the accumulation of slight successive modifications which thus make their appearance in given organs and in a set direction. With Mr. Darwin, on the contrary, the variations being accidental, and due to no special and uniform cause, will not appear for any length of time in any given direction, nor in any given organ, but will be just as liable to appear in one organ as in another, and may be in one generation in one direction, and in another in another. In confirmation of the above, and in illustration of the important consequences that will follow according as we adopt the old or the more recent theory, I would quote the following from Mr. Mivart's 'Genesis of Species.' Shortly before maintaining that two similar structures have often been developed independently of one another, Mr. Mivart points out that if we are dependent upon indefinite variations only, as provided for us by Mr. Darwin, this would be "so improbable as to be practically impossible."[344] The number of possible variations being indefinitely great, "it is therefore an indefinitely great number to one against a similar series of variations occurring and being similarly preserved in any two independent instances." It will be felt (as Mr. Mivart presently insists) that this objection does not apply to a system which maintains that in case an animal feels any given want it will gradually develop the structure which shall meet the want--that is to say, if the want be not so great and so sudden as to extinguish the creature to which it has become a necessity. For if there be such a power of self-adaptation as thus supposed, two or more very widely different animals feeling the same kind of want might easily adopt similar means to gratify it, and hence develop eventually a substantially similar structure; just as two men, without any kind of concert, have often hit upon like means of compassing the same ends. Mr. Spencer's theory--so Mr. Mivart tells us--and certainly that of Lamarck, whose disciple Mr. Spencer would appear to be,[345] admits "a certain peculiar, but limited power of response and adaptation in each animal and plant"--to the conditions of their existence. "Such theories," says Mr. Mivart, "have not to contend against the difficulty proposed, and it has been urged that even very complex extremely similar structures have again and again been developed quite independently one of the other, and this because the process has taken place not by merely haphazard, indefinite variations in all directions, but by the concurrence of some other internal natural law or laws co-operating with external influences and with Natural Selection in the evolution of organic forms. "_It must never be forgotten that to admit any such constant operation of any such unknown natural cause is to deny the purely Darwinian theory which relies upon the survival of the fittest by means of minute fortuitous indefinite variations._ "Among many other obligations which the author has to acknowledge to Professor Huxley, are the pointing out of this very difficulty, and the calling his attention to the striking resemblance between certain teeth of the dog, and of the thylacine, as one instance, and certain ornithic peculiarities of pterodactyles as another."[346] In brief then, changed distribution of use and disuse in consequence of changed conditions of the environment is with Lamarck the main cause of modification. According to Mr. Darwin natural selection, or the survival of favourable but accidental variations, is the most important means of modification. In a word, with Lamarck the variations are definite; with Mr. Darwin indefinite. FOOTNOTES: [333] Vol. ii. chap. i. [334] Vol. ii. chap, xxxiv., ed. 1872. [335] 'Philosophie Zoologique,' ed. M. Martins, Paris, Lyons, 1873, tom. i. p. 24. [336] 'Philosophie Zoologique,' tom. i. p. 72. [337] 'Origin of Species,' p. 3. [338] Ibid. p. 5. [339] 'Origin of Species,' p. 8. [340] Ibid. p. 9. [341] Ibid. p. 158. [342] Ibid. p. 159. [343] 'Origin of Species,' p. 4. [344] 'Genesis of Species,' p. 74, 1871. [345] See _ante_, p. 330, line 1 after heading. [346] 'Genesis of Species,' p. 76, ed. 1871. CHAPTER XX. NATURAL SELECTION CONSIDERED AS A MEANS OF MODIFICATION. THE CONFUSION WHICH THIS EXPRESSION OCCASIONS. When Mr. Darwin says that natural selection is the most important "means" of modification, I am not sure that I understand what he wishes to imply by the word "means." I do not see how the fact that those animals which are best fitted for the conditions of their existence commonly survive in the struggle for life, can be called in any special sense a "means" of modification. "Means" is a dangerous word; it slips too easily into "cause." We have seen Mr. Darwin himself say that Buffon did not enter on "the _causes or means_"[347] of modification, as though these two words were synonymous, or nearly so. Nevertheless, the use of the word "means" here enables Mr. Darwin to speak of Natural Selection as if it were an active cause (which he constantly does), and yet to avoid expressly maintaining that it is a cause of modification. This, indeed, he has not done in express terms, but he does it by implication when he writes, "Natural Selection _might be most effective in giving_ the proper colour to each kind of grouse, and in _keeping_ that colour when once acquired." Such language, says the late Mr. G. H. Lewes, "is misleading;" it makes "selection an agent."[348] It is plain that natural selection cannot be considered a cause of variation; and if not of variation, which is as the rain drop, then not of specific and generic modification, which are as the river; for the variations must make their appearance before they can be selected. Suppose that it is an advantage to a horse to have an especially hard and broad hoof, then a horse born with such a hoof will indeed probably survive in the struggle for existence, but he was not born with the larger and harder hoof _because of his subsequently surviving_. He survived because he was born fit--not, he was born fit because he survived. The variation must arise first and be preserved afterwards. Mr. Darwin therefore is in the following dilemma. If he does not treat natural selection as a cause of variation, the 'Origin of Species' will turn out to have no _raison d'être_. It will have professed to have explained to us the manner in which species has originated, but it will have left us in the dark concerning the origin of those variations which, when added together, amount to specific and generic differences. Thus, as I said in 'Life and Habit,' Mr. Darwin will have made us think we know the whole road, in spite of his having almost ostentatiously blindfolded us at every step in the journey. The 'Origin of Species' would thus prove to be no less a piece of intellectual sleight-of-hand than Paley's 'Natural Theology.' If, on the other hand, Mr. Darwin maintains natural selection to be a cause of variation, this comes to saying that when an animal has varied in an advantageous direction, the fact of its subsequently surviving in the struggle for existence is the cause of its having varied in the advantageous direction--or more simply still--that the fact of its having varied is the cause of its having varied. And this is what we have already seen Mr. Darwin actually to say, in a passage quoted near the beginning of this present book. When writing of the eye he says, "Variation will cause the slight alterations;"[349] but the "slight alterations" _are_ the variations; so that Mr. Darwin's words come to this--that "variation will cause the variations." There does not seem any better way out of this dilemma than that which Mr. Darwin has adopted--namely, to hold out natural selection as "a means" of modification, and thenceforward to treat it as an efficient cause; but at the same time to protest again and again that it is not a cause. Accordingly he writes that "Natural Selection _acts only by the preservation and accumulation_ of small inherited modifications,"[350]--that is to say, it has had no share in inducing or causing these modifications. Again, "What applies to one animal will apply throughout all time to all animals--_that is, if they vary, for otherwise natural selection can effect nothing_"[351]; and again, "for natural selection only _takes advantage of such variations as arise_"[352]--the variations themselves arising, as we have just seen, from variation. Nothing, then, can be clearer from these passages than that natural selection is not a cause of modification; while, on the other hand, nothing can be clearer, from a large number of such passages, as, for instance, "natural selection may be _effective_ in _giving_ and _keeping_ colour,"[353] than that natural selection is an efficient cause; and in spite of its being expressly declared to be only a "means" of modification, it will be accepted as cause by the great majority of readers. Mr. Darwin explains this apparent inconsistency thus:--He maintains that though the advantageous modification itself is fortuitous, or without known cause or principle underlying it, yet its becoming the predominant form of the species in which it appears is due to the fact that those animals which have been advantageously modified commonly survive in times of difficulty, while the unmodified individuals perish: offspring therefore is more frequently left by the favourably modified animal, and thus little by little the whole species will come to inherit the modification. Hence the survival of the fittest becomes a means of modification, though it is no cause of variation. It will appear more clearly later on how much this amounts to. I will for the present content myself with the following quotation from the late Mr. G. H. Lewes in reference to it. Mr. Lewes writes:-- "Mr. Darwin seems to imply that the external conditions which cause a variation are to be distinguished from the conditions which accumulate and perfect such variation, that is to say, he implies a radical difference between the process of variation and the process of selection. This I have already said does not seem to me acceptable; the selection I conceive to be simply the variation which has survived."[354] Certainly those animals and plants which are best fitted for their environment, or, as Lamarck calls it, "_circonstances_"--those animals, in fact, which are best fitted to comply with the conditions of their existence--are most likely to survive and transmit their especial fitness. No one would admit this more readily than Lamarck. This is no theory; it is a commonly observed fact in nature which no one will dispute, but it is not more "a means of modification" than many other commonly observed facts concerning animals. Why is "the survival of the fittest" more a means of modification than, we will say, the fact that animals live at all, or that they live in successive generations, being born, continuing their species, and dying, instead of living on for ever as one single animal in the common acceptation of the term; or than that they eat and drink? The heat whereby the water is heated, the water which is turned into steam, the piston on which the steam acts, the driving wheel, &c., &c., are all one as much as another a means whereby a train is made to go from one place to another; it is impossible to say that any one of them is the main means. So (_mutatis mutandis_) with modification. There is no reason therefore why "the survival of the fittest" should claim to be an especial "means of modification" rather than any other necessary adjunct of animal or vegetable life. I find that the late Mr. G. H. Lewes has insisted on this objection in his 'Physical Basis of Mind.' I observe, also, that in the very passage in which he does so, Mr. Lewes appears to have been misled by Mr. Darwin's use of that dangerous word "means," and, at the same time, by his frequent treatment of natural selection as though it were an active cause; so that Mr. Lewes supposes Mr. Darwin to have fallen into the very error of which, as I have above shown, he is evidently struggling to keep clear--namely, that of maintaining natural selection to be a "cause" of variation. Mr. Lewes then continues:-- "He [Mr. Darwin] separates Natural Selection from all the primary causes of variation either internal or external--either as results of the laws of growth, of the correlations of variation, of use and disuse, &c., and limits it to the slow accumulation of such variations as are profitable in the struggle with competitors. And for his purpose this separation is necessary. But biological philosophy must, I think, regard the distinction as artificial, _referring only to one of the great factors in the production of species_."[355] The fact that one in a brood or litter is born fitter for the conditions of its existence than its brothers and sisters, and, again, the causes that have led to this one's having been born fitter--which last is what the older evolutionists justly dwelt upon as the most interesting consideration in connection with the whole subject--are more noteworthy factors of modification than the factor that an animal, if born fitter for its conditions, will commonly survive longer in the struggle for existence. If the first of these can be explained in such a manner as to be accepted as true, or highly probable, we have a substantial gain to our knowledge. The second is little--if at all--better than a truism. Granted, if it were not generally the case that those forms are most likely to survive which are best fitted for the conditions of their existence, no adaptation of form to conditions of existence could ever have come about. "The survival of the fittest" therefore, or, perhaps better, "the fertility of the fittest," is thus a _sine quâ non_ for modification. But, as we have just insisted, this does not render "the fertility of the fittest" an especial "means of modification," rather than any other _sine quâ non_ for modification. But, to look at the matter in another light. Mr. Darwin maintains natural selection to be "the most important but not the exclusive means of modification." For "natural selection" substitute the words "survival of the fittest," which we may do with Mr. Darwin's own consent abundantly given. To the words "survival of the fittest" add what is elided, but what is, nevertheless, unquestionably as much implied as though it were said openly whenever these words are used, and without which "fittest" has no force--I mean, "for the conditions of their existence." We thus find that when Mr. Darwin says that natural selection is the most important, but not exclusive means of modification, he means that the survival in the struggle for existence of those creatures which are best fitted to comply with the conditions of their existence is the most important, but not exclusive means whereby the descendants of a creature, we will say, A, have become modified, so as to be now represented by a creature, we will say, B. But the word "_circonstances_," so frequently used by Lamarck for the conditions of an animal's existence, contains, by implication, the idea of animals _which shall exist or not according as they fulfil those conditions or fail to fulfil them_. Conditions of existence are conditions which something capable of existing must fulfil if it would exist at all, and nothing is a condition of an animal's existence which that animal need not comply with and may yet continue to exist. Again, the words "animals" and "plants" comprehend the ideas of "fit," "fitter," and "fittest," "unfit," "unfitter," and "unfittest" for certain conditions, for we know of no animals or plants in which we do not observe degrees of fitness or unfitness for their "_circonstances_" or environment, or conditions of existence. The use, therefore, of the term "conditions of existence" is sufficient to show that the person using it intends to imply that those animals and plants will live longest (or survive) and thrive best which are best able to fulfil those conditions. Hence it implies neither more nor less than what is implied by the words "struggle for existence, with consequent survival of the fittest"--that is to say, if we hold the complying with any condition of life to which difficulty is attached to be part of "the struggle" for life, and this we should certainly do. The words "conditions of existence" may, then, be used instead of the "struggle for existence with consequent survival of the fittest," for as they cannot imply any less than the "struggle, &c.," when they are set out in full, and without suppression, so neither do they imply more; for nothing is a condition of existence, in so far as its power of effecting the modification of any animal is concerned, which does not also involve more or less difficulty or struggle; for if there is no difficulty or struggle there will be nothing to bring about change of habit, and hence of structure. This identity of meaning may be also seen if we call to mind that the conditions of existence can be only a synonym for "the conditions of continuing to live," and "the conditions of continuing to live" a synonym for "the conditions of continuing to live a longer time," and "the conditions of continuing to live a longer time," for "the conditions of survival," and "the conditions of survival," for "the survival of the fittest," inasmuch as the being fittest is the condition of being the longest survivor. But we have already seen that "the survival of the fittest," is, according to Mr. Darwin, a synonym for "natural selection"; hence it follows that "the conditions of existence" imply neither more nor less than what is implied by "natural selection" when this expression is properly explained, and may be used instead of it; so that when Mr. Darwin says that "natural selection" is the main but not exclusive means of modification, he must mean, consciously or unconsciously, that "the conditions of existence" are the main but not exclusive means of modification. But this is only falling in with "the views and erroneous grounds of opinion," as Mr. Darwin briefly calls them, of Lamarck himself; a fact which Mr. Darwin's readers would have seen more readily if he had kept to the use of the words "survival of the fittest" instead of "natural selection." Of that expression Mr. Darwin says[356] that it is "more accurate" than natural selection, but naively adds, "and sometimes equally convenient." I have said that there is a practical identity of meaning between "natural selection" and "the conditions of existence," when both expressions are fully extended. I say this, however, without prejudice to my right of maintaining that, of the two expressions, the one is accurate, lucid, and calculated to keep the thread of the argument well in sight of the reader, while the other is inaccurate, and always, if I may say so, less "convenient," as being always liable to lead the reader astray. Nor should it be lost sight of that Lamarck and Dr. Erasmus Darwin maintain that species and genera have arisen _because animals can fashion themselves into accord with_ their conditions, so that, as Lamarck is so continually insisting, the action of the conditions is indirect only--changed use and disuse being the direct causes; while, according to Mr. Darwin, it is natural selection itself (which, as we have seen, is but another way of saying conditions of existence) that is the most important means of modification. The identity of meaning above insisted on was, on the face of it, almost as obscure as that between "_evêque_ and bishop." Yet we know that "_evêque_" is "episc" and "bishop" "piscop," and that "episcopus" is the Latin for bishop; the words, therefore, are really one and the same, in spite of the difference in their appearance. I think I can show, moreover, that Mr. Darwin himself holds natural selection and the conditions of existence to be one and the same thing. For he writes, "in one sense," and it is hard to see any sense but one in what follows, "the conditions of life may be said not only to cause variability" (so that here Mr. Darwin appears to support Lamarck's main thesis) "either directly or indirectly, but likewise to include natural selection; for the conditions determine whether this or that variety shall survive."[357] But later on we find that "the expression of conditions of existence, so often insisted upon by the illustrious Cuvier" (and surely also by the illustrious Lamarck, though he calls them "_circonstances_") "is fully embraced by the principle of natural selection."[358] So we see that the conditions of life "_include_" natural selection, and yet the conditions of existence "_are fully embraced by_" natural selection, which, I take it, is an enigmatic way of saying that they are one and the same thing, for it is not until two bodies absolutely coincide and occupy the same space that the one can be said both to include and to be embraced by the other. The difficulty, again, of understanding Mr. Darwin's meaning is enhanced by his repeatedly writing of "natural selection," or the fact that the fittest survive in the struggle for existence, as though it were the same thing as "evolution" or the descent, through the accumulation of small modifications in many successive generations, of one species from another and different one. In the concluding and recapitulatory chapter of the 'Origin of Species,' he writes:-- "Turning to geographical distribution, the difficulties encountered _on the theory of descent with modification_ are serious enough;"[359] and in the next paragraph, "As, according to _the theory of natural selection, &c._," the context showing that in each case descent with modification is intended. Again:-- "On the theory of the _natural selection_ of successive, slight, but profitable, modifications,"[360] that is to say, on the theory of the survival of the fittest; while on the next page we find "_the theory of descent with modification_," and "_the principle of natural selection_," used as though they were convertible terms. Again:-- "The existence of closely allied or representative species in any two areas implies, _on the theory of descent with modification, &c._;"[361] and, in the next paragraph, "_the theory of natural selection_, with its contingencies of extinction and divergence of character," is substituted as though the two expressions were identical. This is calculated to mislead. Independently of the fact that "natural selection," or "the survival of the fittest," is in no sense a theory, but simply an observed fact, yet even if the words are allowed to stand for "descent with modification by means of natural selection," it is still misleading to write as though this were synonymous with "the theory of evolution," or "the theory of descent with modification." To do this prevents the reader from bearing in mind that "evolution by means of the circumstance-suiting power of plants and animals" as advanced by the earlier evolutionists; and "evolution by means of lucky accidents" with comparatively little circumstance-suiting power, are two very different things, of which the one may be true and the other untrue. It leads the reader to forget that evolution by no means stands or falls with evolution by means of natural selection, and makes him think that if he accepts evolution at all, he is bound to Mr. Darwin's view of it. Hence, when he falls in with such writers as Professor Mivart and the Rev. J. J. Murphy, who show, and very plainly, that the survival of the fittest, unsupplemented by something which shall give a definite aim to the variations which successively occur, fails to account for the coadaptations of need and structure, he imagines that evolution has much less to say for itself than it really has. If Mr. Darwin, instead of taking the line which he has thought fit to adopt towards Buffon, Dr. Erasmus Darwin, Lamarck, and the author of the 'Vestiges,' had shown us what these men taught, why they taught it, wherein they were wrong, and how he proposed to set them right, he would have taken a course at once more agreeable with ordinary practice, and more likely to clear misconception from his own mind and from those of his readers. Mr. Darwin says,[362] "it is easy to hide our ignorance under such expressions as 'the plan of creation' and 'unity of design.'" Surely, also, it is easy to hide want of precision of thought, and the absence of any fundamental difference between his own main conclusion and that of Dr. Darwin and Lamarck whom he condemns, under the term "natural selection." I assure the reader that I find the task of forming a clear, well-defined conception of Mr. Darwin's meaning, as expressed in his 'Origin of Species,' comparable only to that of one who has to act on the advice of a lawyer who has obscured the main issue as far as he can, and whose chief aim has been to make as many loopholes as possible for himself to escape through in case of his being called to account. Or, again, to that of one who has to construe an Act of Parliament which was originally framed so as to throw dust in the eyes of those who would oppose the measure, and which, having been since found unworkable, has had clauses repealed and inserted up and down it, till it is in an inextricable tangle of confusion and contradiction. As an example of my meaning, I will quote a passage to which I called attention in 'Life and Habit.' It runs:-- "In the earlier editions of this work I underrated, as now seems probable, the frequency and importance of modifications due to spontaneous variability. But it is impossible to attribute to _this cause_" (i. e. spontaneous variability, which is itself only an expression for unknown causes) "the innumerable structures which are so well adapted to the habits of life of each species. I can no more believe in _this_" (i. e. that the innumerable structures, &c., can be due to unknown causes) "than that the well adapted form of a racehorse or greyhound, which, before the principle of selection by man was well understood, excited so much surprise in the minds of the older naturalists, can _thus_" (i. e. by attributing them to unknown causes) "be explained."[363] This amounts to saying that unknown causes can do so much, but cannot do so much more. On this passage I wrote, in 'Life and Habit':-- "It is impossible to believe that, after years of reflection upon his subject, Mr. Darwin should have written as above, especially in such a place, if his mind was clear about his own position. Immediately after the admission of a certain amount of miscalculation there comes a more or less exculpatory sentence, which sounds so right that ninety-nine people out of a hundred would walk through it, unless led by some exigency of their own position to examine it closely, but which yet, upon examination, proves to be as nearly meaningless as a sentence can be."[364] No one, to my knowledge, has impugned the justice of this criticism, and I may say that further study of Mr. Darwin's works has only strengthened my conviction of the confusion and inaccuracy of thought, which detracts so greatly from their value. So little is it generally understood that "evolution" and what is called "Darwinism" convey indeed the same main conclusion, but that this conclusion has been reached by two distinct roads, one of which is impregnable, while the other has already fallen into the hands of the enemy, that in the last November number of the 'Nineteenth Century' Professor Tyndall, while referring to descent with modification or evolution, speaks of it as though it were one and inseparable from Mr. Darwin's theory that it has come about mainly by means of natural selection. He writes:-- "_Darwin's theory_, as pointed out nine or ten years ago by Helmholtz and Hooker, was then exactly in this condition of growth; and had they to speak of the subject to-day they would be able to announce an enormous strengthening of the theoretic fibre. Fissures in continuity which then existed, and which left little hope of being ever spanned, have been since bridged over, so that the further _the theory_ is tested the more fully does it harmonize with progressive experience and discovery. We shall never probably fill all the gaps; but this will not prevent a profound belief in the truth of _the theory_ from taking root in the general mind. Much less will it justify a total denial of _the theory_. The man of science, who assumes in such a case the position of a denier, is sure to be stranded and isolated." This is in the true vein of the professional and orthodox scientist; of that new orthodoxy which is clamouring for endowment, and which would step into the Pope's shoes to-morrow, if we would only let it. If Professor Tyndall means that those who deny evolution will find themselves presently in a very small minority, I agree with him; but if he means that evolution is Mr. Darwin's theory, and that he who rejects what Mr. Darwin calls "the theory of natural selection" will find himself stranded, his assertion will pass muster with those only who know little of the history and literature of evolution. FOOTNOTES: [347] 'Origin of Species,' Hist. Sketch, p. xiii. [348] 'Physical Basis of Mind,' p. 108. [349] 'Origin of Species,' p. 146. [350] Ibid. p. 75. [351] Ibid. p. 88. [352] 'Origin of Species,' p. 98. [353] Ibid. p. 66. [354] 'Physical Basis of the Mind,' p. 109, 1878. [355] 'Physical Basis of the Mind,' p. 107, 1878. [356] 'Origin of Species,' p. 49. [357] 'Origin of Species,' p. 107. [358] Ibid. p. 166. [359] 'Origin of Species,' p. 406. [360] Ibid, p. 416. [361] Ibid. p. 419. [362] 'Origin of Species,' p. 422. [363] 'Origin of Species,' p. 171, ed. 1876. [364] 'Life and Habit,' p. 260. CHAPTER XXI. MR. DARWIN'S DEFENCE OF THE EXPRESSION, NATURAL SELECTION--PROFESSOR MIVART AND NATURAL SELECTION. So important is it that we should come to a clear understanding upon the positions taken by Mr. Darwin and Lamarck respectively, that at the risk of wearying the reader I will endeavour to exhaust this subject here. In order to do so, I will follow Mr. Darwin's answer to those who have objected to the expression, "natural selection." Mr. Darwin says:-- "Several writers have misapprehended or objected to the term 'natural selection.' Some have even imagined that natural selection induces variability."[365] And small wonder if they have; but those who have fallen into this error are hardly worth considering. The true complaint is that Mr. Darwin has too often written of "natural selection" as though it does induce variability, and that his language concerning it is so confusing that the reader is not helped to see that it really comes to nothing but a cloak of difference from his predecessors, under which there lurks a concealed identity of opinion as to the main facts. The reader is thus led to look upon it as something positive and special, and, in spite of Mr. Darwin's disclaimer, to think of it as an actively efficient cause. Few will deny that this complaint is a just one, or that ninety-nine out of a hundred readers of average intelligence, if asked, after reading Mr. Darwin's 'Origin of Species,' what was the most important cause of modification, would answer "natural selection." Let the same readers have read the 'Zoonomia' of Dr. Erasmus Darwin, or the 'Philosophie Zoologique' of Lamarck, and they would at once reply, "the wishes of an animal or plant, as varying with its varying conditions," or more briefly, "sense of need." "Whereas," continues Mr. Darwin, "it" (natural selection) "implies only the preservation of such variations as arise, and are beneficial to the being under its conditions of life. No one objects to agriculturists speaking of the potent effects of man's selection." Of course not; for there _is_ an actual creature man, who actually does select with a set purpose in order to produce such and such a result, which result he presently produces. "And in this case the individual differences given by nature, which man for some object selects, must first occur." This shows that the complaint has already reached Mr. Darwin, that in not showing us how "the individual differences first occur," he is really leaving us absolutely in the dark as to the cause of all modification--giving us an 'Origin of Species' with "the origin" cut out; but I do not think that any reader who has not been compelled to go somewhat deeply into the question would find out that this is the real gist of the objection which Mr. Darwin is appearing to combat. A general impression is left upon the reader that some very foolish objectors are being put to silence, that Mr. Darwin is the most candid literary opponent in the world, and as just as Aristides himself; but if the unassisted reader will cross-question himself what it is all about, I shall be much surprised if he is ready with his answer. "Others"--to resume our criticism on Mr. Darwin's defence--"have objected that the term implies conscious choice in the animals which become modified, and it has been even urged that as plants have no volition, natural selection is not applicable to them!" This--unfortunately--must have been the objection of a slovenly, or wilfully misapprehending reader, and was unworthy of serious notice. But its introduction here tends to draw the reader from the true ground of complaint, which is that at the end of Mr. Darwin's book we stand much in the same place as we did when we started, as regards any knowledge of what is the "origin of species." "In the literal sense of the word, no doubt, natural selection is a false term." Then why use it when another, and, by Mr. Darwin's own admission, a "more accurate" one is to hand in "the survival of the fittest"?[366] This term is not appreciably longer than natural selection. Mr. Darwin may say, indeed, that it is "sometimes" as convenient a term as natural selection; but the kind of men who exercise permanent effect upon the opinions of other people will bid such a passage as this stand aside somewhat sternly. If a term is not appreciably longer than another, and if at the same time it more accurately expresses the idea which is intended to be conveyed, it is not sometimes only, but always, more convenient, and should immediately be substituted for the less accurate one. No one complains of the use of what is, strictly speaking, an inaccurate expression, when it is nevertheless the best that we can get. It may be doubted whether there is any such thing possible as a perfectly accurate expression. All words that are not simply names of things are apt to turn out little else than compendious false analogies; but we have a right to complain when a writer tells us that he is using a less accurate expression when a more accurate one is ready to his hand. Hence, when Mr. Darwin continues, "Who ever objected to chemists speaking of the elective affinities of the various elements? and yet an acid cannot strictly be said to elect the base with which it by preference combines," he is beside the mark. Chemists do not speak of "elective affinities" in spite of there being a more accurate and not appreciably longer expression at their disposal. "It has been said," continues Mr. Darwin, "that I speak of natural selection as an active power or deity. But who objects to an author speaking of the attraction of gravity? Everyone knows what is meant and implied by such metaphorical expressions, and they are almost necessary for brevity." Mr. Darwin certainly does speak of natural selection "acting," "accumulating," "operating"; and if "every-one knew what was meant and implied by this metaphorical expression," as they now do, or think they do, in the case of the attraction of gravity, there might be less ground of complaint; but the expression was known to very few at the time Mr. Darwin introduced it, and was used with so much ambiguity, and with so little to protect the reader from falling into the error of supposing that it was the cause of the modifications which we see around us, that we had a just right to complain, even in the first instance; much more should we do so on the score of the retention of the expression when a more accurate one had been found. If the "survival of the fittest" had been used, to the total excision of "natural selection" from every page in Mr. Darwin's book--it would have been easily seen that "the survival of the fittest" is no more a cause of modification, and hence can give no more explanation concerning the origin of species, than the fact of a number of competitors in a race failing to run the whole course, or to run it as quickly as the winner, can explain how the winner came to have good legs and lungs. According to Lamarck, the winner will have got these by means of sense of need, and consequent practice and training, on his own part, and on that of his forefathers; according to Mr. Darwin, the "most important means" of his getting them is his "happening" to be born with them, coupled, with the fact that his uncles and aunts for many generations could not run so well as his ancestors in the direct line. But can the fact of his uncles and aunts running less well than his fathers and mothers be a means of his fathers and mothers coming to run _better than they used to run_? If the reader will bear in mind the idea of the runners in a race, it will help him to see the point at issue between Mr. Darwin and Lamarck. Perhaps also the double meaning of the word race, as expressing equally a breed and a competition, may not be wholly without significance. What we want to be told is, not that a runner will win the prize if he can run "ever such a little" faster than his fellows--we know this--but by what process he comes to be able to run ever such a little faster. "So, again," continues Mr. Darwin, "it is difficult to avoid personifying nature, but I mean by nature only the aggregate action and product of many natural laws, and by laws the sequence of events as ascertained by us." This, again, is raising up a dead man in order to knock him down. Nature has been personified for more than two thousand years, and every one understands that nature is no more really a woman than hope or justice, or than God is like the pictures of the mediæval painters; no one whose objection was worth notice could have objected to the personification of nature. Mr. Darwin concludes:-- "With a little familiarity, such superficial objections will be forgotten."[367] As a matter of fact, I do not see any greater tendency to acquiesce in Mr. Darwin's claim on behalf of natural selection than there was a few years ago, but on the contrary, that discontent is daily growing. To say nothing of the Rev. J. J. Murphy and Professor Mivart, the late Mr. G. H. Lewes did not find the objection a superficial one, nor yet did he find it disappear "with a little familiarity"; on the contrary, the more familiar he became with it the less he appeared to like it. I may even go, without fear, so far as to say that any writer who now uses the expression "natural selection," writes himself down thereby as behind the age. It is with great pleasure that I observe Mr. Francis Darwin in his recent lecture[368] to have kept clear of it altogether, and to have made use of no expression, and advocated no doctrine to which either Dr. Erasmus Darwin or Lamarck would not have readily assented. I think I may affirm confidently that a few years ago any such lecture would have contained repeated reference to Natural Selection. For my own part I know of few passages in any theological writer which please me less than the one which I have above followed sentence by sentence. I know of few which should better serve to show us the sort of danger we should run if we were to let men of science get the upper hand of us. Natural Selection, then, is only another way of saying "Nature." Mr. Darwin seems to be aware of this when he writes, "Nature, if I may be allowed to personify the natural preservation or survival of the fittest." And again, at the bottom of the same page, "It may metaphorically be said that _natural selection is daily and hourly scrutinizing_ throughout the world the slightest variations."[369] It may be metaphorically said that _Nature_ is daily and hourly scrutinizing, but it cannot be said consistently with any right use of words, metaphorical or otherwise, that natural selection scrutinizes, unless natural selection is merely a somewhat cumbrous synonym for Nature. When, therefore, Mr. Darwin says that natural selection is the "most important, but not the exclusive means" whereby any modification has been effected, he is really saying that Nature is the most important means of modification--which is only another way of telling us that variation causes variations, and is all very true as far as it goes. I did not read Professor Mivart's 'Lessons from Nature,' until I had written all my own criticism on Mr. Darwin's position. From that work, however, I now quote the following:-- "It cannot then be contested that the far-famed 'Origin of Species,' that, namely, by 'Natural Selection,' has been repudiated in fact, though not expressly even by its own author. This circumstance, which is simply undeniable, might dispense us from any further consideration of the hypothesis itself. But the "conspiracy of silence," which has accompanied the repudiation tends to lead the unthinking many to suppose that the same importance still attaches to it as at first. On this account it may be well to ask the question, what, after all, _is_ 'Natural Selection'? "The answer may seem surprising to some, but it is none the less true, that 'Natural Selection' is simply nothing. It is an apparently positive name for a really negative effect, and is therefore an eminently misleading term. By 'Natural Selection' is meant the result of all the destructive agencies of Nature, destructive to individuals and to races by destroying their lives or their powers of propagation. Evidently, _the cause of the distinction of species_ (supposing such distinction to be brought about in natural generation) _must be that which causes variation, and variation in one determinate direction in at least several individuals simultaneously_." I should like to have added here the words "and during many successive generations," but they will go very sufficiently without saying. "At the same time," continues Professor Mivart, "it is freely conceded that the destructive agencies in nature do succeed in preventing the perpetuation of monstrous, abortive, and feeble attempts at the performance of the evolutionary process, that they rapidly remove antecedent forms when new ones are evolved more in harmony with surrounding conditions, and that their action results in the formation of new characters when these have once attained sufficient completeness to be of real utility to their possessor. "Continued reflection, and five years further pondering over the problems of specific origin have more and more convinced me that the conception, that the origin of all species 'man included' is due simply to conditions which are (to use Mr. Darwin's own words) 'strictly accidental,' is a conception utterly irrational." . . . . . . "With regard to the conception as now put forward by Mr. Darwin, I cannot truly characterize it but by an epithet which I employ only with much reluctance. I weigh my words and have present to my mind the many distinguished naturalists who have accepted the notion, and yet I cannot hesitate to call it a '_puerile hypothesis_.'"[370] I am afraid I cannot go with Professor Mivart farther than this point, though I have a strong feeling as though his conclusion is true, that "the material universe is always and everywhere sustained and directed by an infinite cause, for which to us the word mind is the least inadequate and misleading symbol." But I feel that any attempt to deal with such a question is going far beyond that sphere in which man's powers may be at present employed with advantage: I trust, therefore, that I may never try to verify it, and am indifferent whether it is correct or not. Again, I should probably differ from Professor Mivart in finding this mind inseparable from the material universe in which we live and move. So that I could neither conceive of such a mind influencing and directing the universe from a point as it were outside the universe itself, nor yet of a universe as existing without there being present--or having been present--in its every particle something for which mind should be the least inadequate and misleading symbol. But the subject is far beyond me. As regards Professor Mivart's denunciations of natural selection, I have only one fault to find with them, namely, that they do not speak out with sufficient bluntness. The difficulty of showing the fallacy of Mr. Darwin's position, is the difficulty of grasping a will-o'-the-wisp. A concluding example will put this clearly before the reader, and at the same time serve to illustrate the most tangible feature of difference between Mr. Darwin and Lamarck. FOOTNOTES: [365] 'Origin of Species,' p. 62. [366] 'Origin of Species,' p. 49. [367] 'Origin of Species,' p. 63. [368] 'Nature,' March 14 and 21, 1878. [369] 'Origin of Species,' p. 65. [370] 'Lessons from Nature,' p. 300. CHAPTER XXII. THE CASE OF THE MADEIRA BEETLES AS ILLUSTRATING THE DIFFERENCE BETWEEN THE EVOLUTION OF LAMARCK AND OF MR. CHARLES DARWIN--CONCLUSION. An island of no very great extent is surrounded by a sea which cuts it off for many miles from the nearest land. It lies a good deal exposed to winds, so that the beetles which live upon it are in continual danger of being blown out to sea if they fly during the hours and seasons when the wind is blowing. It is found that an unusually large proportion of the beetles inhabiting this island are either without wings or have their wings in a useless and merely rudimentary state; and that a large number of kinds which are very common on the nearest mainland, but which are compelled to use their wings in seeking their food, are here entirely wanting. It is also observed that the beetles on this island generally lie much concealed until the wind lulls and the sun shines. These are the facts; let us now see how Lamarck would treat them. Lamarck would say that the beetles once being on this island it became one of the conditions of their existence that they should not get blown out to sea. For once blown out to sea, they would be quite certain to be drowned. Beetles, when they fly, generally fly for some purpose, and do not like having that purpose interfered with by something which can carry them all-whithers, whether they like it or no. If they are flying and find the wind taking them in a wrong direction, or seaward--which they know will be fatal to them--they stop flying as soon as may be, and alight on _terra firma_. But if the wind is very prevalent the beetles can find but little opportunity for flying at all: they will therefore lie quiet all day and do as best they can to get their living on foot instead of on the wing. There will thus be a long-continued disuse of wings, and this will gradually diminish the development of the wings themselves, till after a sufficient number of generations these will either disappear altogether, or be seen in a rudimentary condition only. For each beetle which has made but little use of its wings will be liable to leave offspring with a slightly diminished wing, some other organ which has been used instead of the wing becoming proportionately developed. It is thus seen that the conditions of existence are the indirect cause of the wings becoming rudimentary, inasmuch as they preclude the beetles from using them; the disuse however on the part of the beetles themselves is the direct cause. Now let us see how Mr. Darwin deals with the same case. He writes:-- "In some cases we might easily set down to disuse, modifications of structure which are _wholly_ or _mainly_ due to natural selection." Then follow the facts about the beetles of Madeira, as I have given them above. While we are reading them we naturally make up our minds that the winglessness of the beetles will prove due either wholly, or at any rate mainly, to natural selection, and that though it would be easy to set it down to disuse, yet we must on no account do so. The facts having been stated, Mr. Darwin continues:--"These several considerations make me believe that the wingless condition of so many Madeira beetles is mainly due to the action of natural selection," and when we go on to the words that immediately follow, "combined probably with disuse," we are almost surprised at finding that disuse has had anything to do with the matter. We feel a languid wish to know exactly how much and in what way it has entered into the combination; but we find it difficult to think the matter out, and are glad to take it for granted that the part played by disuse must be so unimportant that we need not consider it. Mr. Darwin continues:-- "For during many successive generations each individual beetle which flew least, either from its wings having been ever so little less perfectly developed, or from indolent habit, will have had the best chance of surviving from not having been blown out to sea; and on the other hand those beetles which most readily took to flight would oftenest be blown out to sea and perish."[371] So apt are we to believe what we are told, when it is told us gravely and with authority, and when there is no statement at hand to contradict it, that we fail to see that Mr. Darwin is all the time really attributing the winglessness of the Madeira beetles either to the _quâ_ him _unknown causes_ which have led to the "ever so little less perfect development of wing" on the part of the beetles that leave offspring--that is to say, is admitting that he can give no account of the matter--or else to the "indolent habit" of the parent beetles which has led them to disuse their wings, and hence gradually to lose them--which is neither more nor less than the "erroneous grounds of opinion," and "well-known doctrine" of Lamarck. For Mr. Darwin cannot mean that the fact of some beetles being blown out to sea is the most important means whereby certain other beetles come to have smaller wings--that the Madeira beetles in fact come to have smaller wings mainly because their large winged uncles and aunts--go away. But if he does not mean this, what becomes of natural selection? For in this case we are left exactly where Lamarck left us, and must hold that such beetles as have smaller wings have them because the conditions of life or "circumstances" in which their parents were placed, rendered it inconvenient to them to fly, and thus led them to leave off using their wings. Granted, that if there had been nothing to take unmodified beetles away, there would have been less room and scope for the modified beetles; also that unmodified beetles would have intermixed with the modified, and impeded the prevalence of the modification. But anything else than such removal of unmodified individuals would be contrary to our hypothesis. The very essence of conditions of existence is that there _shall be_ something to take away those which do not comply with the conditions; if there is nothing to render such and such a course a _sine quâ non_ for life, there is no condition of existence in respect of this course, and no modification according to Lamarck could follow, as there would be no changed distribution of use. I think that if I were to leave this matter here I should have said enough to make the reader feel that Lamarck's system is direct, intelligible and sufficient--while Mr. Darwin's is confused and confusing. I may however quote Mr. Darwin himself as throwing his theory about the Madeira beetles on one side in a later passage, for he writes:-- "It is probable that _disuse has been the main agent in rendering organs rudimentary_," or in other words that Lamarck was quite right--nor does one see why if disuse is after all the main agent in rendering an organ rudimentary, use should not have been the main agent in developing it--but let that pass. "It (disuse) would at first lead," continues Mr. Darwin, "by slow steps to the more and more complete reduction of a part, until at last it became rudimentary--as in the case of the eyes of animals inhabiting dark caverns, and of the wings of birds inhabiting oceanic islands, which have seldom been forced by beasts of prey to take flight, and have ultimately lost the power of flying. Again, an organ useful under certain conditions, might become injurious under others, _as with the wings of beetles living on small and exposed islands_;"[372] so that the rudimentary condition of the Madeira beetles' wings is here set down as mainly due to disuse--while above we find it mainly due to natural selection--I should say that immediately after the word "islands" just quoted, Mr. Darwin adds "and in this case natural selection will have aided in reducing the organ, until it was rendered harmless and rudimentary," but this is Mr. Darwin's manner, and must go for what it is worth. How refreshing to turn to the simple straightforward language of Lamarck. "Long continued disuse," he writes, "in consequence of the habits which an animal has contracted, gradually reduces an organ, and leads to its final disappearance.... "Eyes placed in the head form an essential part of that plan on which we observe all vertebrate organisms to be constructed. Nevertheless the mole which uses its vision very little, has eyes which are only very small and hardly apparent. "The _aspalax_ of Olivier, which lives underground like the mole, and exposes itself even less than the mole to the light of day, has wholly lost the use of its sight, nor does it retain more than mere traces of visual organs, these traces again being hidden under the skin and under certain other parts which cover them up and leave not even the smallest access to the light. The Proteus, an aquatic reptile akin to the Salamander and living in deep and obscure cavities under water, has, like the aspalax, no longer anything but traces of eyes remaining--traces which are again entirely hidden and covered up.[373] "The following consideration should be decisive. "Light cannot penetrate everywhere, and as a consequence, animals which live habitually in places which it cannot reach, do not have an opportunity of using eyes, even though they have got them; but animals which form part of a system of organization which comprises eyes as an invariable rule among its organs, must have had eyes originally. Since then we find among these animals some which have lost their eyes, and which have only concealed traces of these organs, it is evident that the impoverishment, and even disappearance of the organs in question, must be the effect of long-continued disuse. "A proof of this is to be found in the fact that the organ of hearing is never in like case with that of sight; we always find it in animals of whose system of organization hearing is a component part; and for the following reason, namely, that sound, which is the effect of vibration upon the ear, can penetrate everywhere, and pass even through massive intermediate bodies. Any animal, therefore, with an organic system of which the ear is an essential part, can always find a use for its ears, no matter where it inhabits. We never, therefore, come upon rudimentary ears among the vertebrata, and when, going down the scale of life lower than the vertebrata, we come to a point at which the ear is no longer to be found; we never come upon ears again in any lower class. "Not so with the organ of sight: we see this organ disappear, reappear, and disappear again with the possibility or impossibility of using eyes on the part of the creature itself.[374] "The great development of mantle in the acephalous molluscs has rendered eyes, and even a head, entirely useless to them. These organs, though belonging to the type of the organism, and by rights included in it, have had to disappear and become annihilated owing to continued default of use. . . . . . . "Many insects which, by the analogy of their order and even genus, should have wings, have nevertheless lost them more or less completely through disuse. A number of coleoptera, orthoptera, hymenoptera, and hemiptera give us examples, the habits of these animals never leading them to use their wings."[375] * * * * * I will here bring this present volume to a conclusion, hoping, however, to return to the same subject shortly, but to that part of it which bears upon longevity and the phenomena of old age. In 'Life and Habit' I pointed out that if differentiations of structure and instinct are considered as due to the different desires under different circumstances of an organism, which must be regarded as a single creature, though its development has extended over millions of years, and which is guided mainly by habit and memory until some disturbing cause compels invention--then the longevity of each generation or stage of this organism should depend upon the lateness of the average age of reproduction in each generation; so that an organism (using the word in its usual signification) which did not upon the average begin to reproduce itself till it was twenty, should be longer lived than one that on the average begins to reproduce itself at a year old. I also maintained that the phenomena of old age should be referred to failure of memory on the part of the organism, which in the embryonic stages, infancy, youth, and early manhood, leans upon the memory of what it did when it was in the persons of its ancestors; in middle life, carries its action onward by means of the impetus, already received, and by the force of habit; and in old age becomes puzzled, having no experience of any past existence at seventy-five, we will say, to guide it, and therefore forgetting itself more and more completely till it dies. I hope to extend this, and to bring forward arguments in support of it in a future work. Of the importance of the theory put forward in 'Life and Habit'--I am daily more and more convinced. Unless we admit oneness of personality between parents and offspring, memory of the often repeated facts of past existences, the latency of that memory until it is rekindled by the presence of the associated ideas, or of a sufficient number of them, and the far-reaching consequences of the unconsciousness which results from habitual action, evolution does not greatly add to our knowledge as to how we shall live here to the best advantage. Add these considerations, and its value as a guide becomes immediately apparent; a new light is poured upon a hundred problems of the greatest delicacy and difficulty. Not the least interesting of these is the gradual extension of human longevity--an extension, however, which cannot be effected till many many generations as yet unborn have come and gone. There is nothing, however, to prevent man's becoming as long lived as the oak if he will persevere for many generations in the steps which can alone lead to this result. Another interesting achievement which should be more quickly attainable, though still not in our own time, is the earlier maturity of those animals whose rapid maturity is an advantage to us, but whose longevity is not to our purpose. * * * * * The question--Evolution or Direct Creation of all species?--has been settled in favour of Evolution. A hardly less interesting and important battle has now to be fought over the question whether we are to accept the evolution of the founders of the theory--with the adjuncts hinted at by Dr. Darwin and Mr. Matthew, and insisted on, so far as I can gather, by Professor Hering and myself--or the evolution of Mr. Darwin, which denies the purposiveness or teleology inherent in evolution as first propounded. I am assured that such of my readers as I can persuade to prefer the old evolution to the new will have but little reason to regret their preference. * * * * * P.S.--As these sheets leave my hands, my attention is called to a review of Professor Haeckel's 'Evolution of Man,' by Mr. A. E. Wallace, in the 'Academy' for April 12, 1879. "Professor Haeckel maintains," says Mr. Wallace, "_that the struggle for existence in nature evolves new forms without design, just as the will of man produces new varieties in cultivation with design_." I maintain in preference with the older evolutionists, that in consequence of change in the conditions of their existence, _organisms design new forms for themselves, and carry those designs out in additions to, and modifications of, their own bodies_. "The science of rudimentary organs," continues Mr. Wallace, "which Haeckel terms 'dysteleology, or the doctrine of purposelessness,' is here discussed, and a number of interesting examples are given, the conclusion being that they prove the mechanical or monistic conception of the origin of organisms to be correct, and the idea of any 'all-wise creative plan an ancient fable.'" I see no reason to suppose, or again not to suppose, an all-wise creative plan. I decline to go into this question, believing it to be not yet ripe, nor nearly ripe, for consideration. I see purpose, however, in rudimentary organs as much as in useful ones, but a spent or extinct purpose--a purpose which has been fulfilled, and is now forgotten--the rudimentary organ being repeated from force of habit, indolence, and dislike of change, so long as it does not, to use the words of Buffon, "stand in the way of the fair development" of other parts which are found useful and necessary. I demur, therefore, to the inference of "purposelessness" which I gather that Professor Haeckel draws from these organs. In the 'Academy' for April 19, 1879, Mr. Wallace quotes Professor Haeckel as saying that our "highly purposive and admirably-constituted sense-organs have developed without premeditated aim; that they have originated by the same mechanical process of Natural Selection, by the same constant interaction of Adaptation and Heredity [what _is_ Heredity but another word for unknown causes, unless it is explained in some such manner as in 'Life and Habit'?] by which all the other purposive contrivances of the animal organization have been slowly and gradually evolved during the struggle for existence." I see no evidence for "premeditated aim" at any modification very far in advance of an existing organ, any more than I do for "premeditated aim" on man's part at any as yet inconceivable mechanical invention; but as in the case of man's inventions, so also in that of the organs of animals and plants, modification is due to the accumulation of small, well-considered improvements, as found necessary in practice, and the conduct of their affairs. Each step having been purposive, the whole road has been travelled purposively; nor is the purposiveness of such an organ, we will say, as the eye, barred by the fact that invention has doubtless been aided by some of those happy accidents which from time to time happen to all who keep their wits about them, and know how to turn the gifts of Fortune to account. FOOTNOTES: [371] 'Origin of Species,' p. 109. [372] 'Origin of Species, p. 401. [373] 'Phil. Zool.,' tom. i. p. 242. [374] 'Phil. Zool.,' tom. i. p. 244. [375] 'Phil. Zool.,' tom. i. p. 245. APPENDIX. CHAPTER I. REVIEWS OF 'EVOLUTION, OLD AND NEW.' Those who have been at the pains to read the foregoing book will, perhaps, pardon me if I put before them a short account of the reception it has met with: I will not waste time by arguing with my critics at any length; it will be enough if I place some of their remarks upon my book under the same cover as the book itself, with here and there a word or two of comment. The only reviews which have come under my notice appeared in the 'Academy' and the 'Examiner,' both of May 17, 1879; the 'Edinburgh Daily Review,' May 23, 1879; 'City Press,' May 21, 1879; 'Field,' May 26, 1879; 'Saturday Review,' May 31, 1879; 'Daily Chronicle,' May 31, 1879; 'Graphic' and 'Nature,' both June 12, 1879; 'Pall Mall Gazette,' June 18, 1879; 'Literary World,' June 20, 1879; 'Scotsman,' June 24, 1879; 'British Journal of Homoeopathy' and 'Mind,' both July 1, 1879; 'Journal of Science,' July 18, 1879; 'Westminster Review,' July, 1879; 'Athenæum,' July 26, 1879; 'Daily News,' July 29, 1879; 'Manchester City News,' August 16, 1879; 'Nonconformist,' November 26, 1879; 'Popular Science Review,' Jan. 1, 1880; 'Morning Post,' Jan. 12, 1880. Some of the most hostile passages in the reviews above referred to are as follows:-- "From beginning to end, our eccentric author treats us to a dazzling flood of epigram, invective, and what appears to be argument; and finally leaves us without a single clear idea as to what he has been driving at." . . . . . . "Mr. Butler comes forward, as it were, to proclaim himself a professional satirist, and a mystifier who will do his best to leave you utterly in the dark with regard to his system of juggling. Is he a teleological theologian making fun of evolution? Is he an evolutionist making fun of teleology? Is he a man of letters making fun of science? Or is he a master of pure irony making fun of all three, and of his audience as well? For our part we decline to commit ourselves, and prefer to observe, as Mr. Butler observes of Von Hartmann, that if his meaning is anything like what he says it is, we can only say that it has not been given us to form any definite conception whatever as to what that meaning may be."--'Academy,' May 17, 1879, Signed Grant Allen. * * * * * Here is another criticism of "Evolution, Old and New"--also, I believe I am warranted in saying, by Mr. Grant Allen. These two criticisms appeared on the same day; how many more Mr. Allen may have written later on I do not know. We find the writer who in the 'Academy' declares that he has been left without "a single clear idea" as to what 'Evolution, Old and New,' has been driving at saying on the same day in the 'Examiner' that 'Evolution, Old and New,' "has a more evident purpose than any of its predecessors." If so, I am afraid the predecessors must have puzzled Mr. Allen very unpleasantly. What the purpose of 'Evolution, Old and New,' is, he proceeds to explain:-- "As to his (Mr. Butler's) main argument, it comes briefly to this: natural selection does not originate favourable varieties, it only passively permits them to exist; therefore it is the unknown cause which produced the variations, not the natural selection which spared them, that ought to count as the mainspring of evolution. That unknown cause Mr. Butler boldly declares to be the will of the organism itself. An intelligent ascidian wanted a pair of eyes,[376] so set to work and made itself a pair, exactly as a man makes a microscope; a talented fish conceived the idea of walking on dry land, so it developed legs, turned its swim bladder into a pair of lungs, and became an amphibian; an æsthetic guinea-fowl admired bright colours, so it bought a paint-box, studied Mr. Whistler's ornamental designs, and, painting itself a gilded and ocellated tail, was thenceforth a peacock. But how about plants? Mr. Butler does not shirk even this difficulty. The theory must be maintained at all hazards.... This is the sort of mystical nonsense from which we had hoped Mr. Darwin had for ever saved us."--'Examiner,' May 17, 1879. * * * * * In this last article, Mr. Allen has said that I am a man of genius, "with the unmistakable signet-mark upon my forehead." I have been subjected to a good deal of obloquy and misrepresentation at one time or another, but this passage by Mr. Allen is the only one I have seen that has made me seriously uneasy about the prospects of my literary reputation. I see Mr. Allen has been lately writing an article in the 'Fortnightly Review' on the decay of criticism. Looking over it somewhat hurriedly, my eye was arrested by the following:-- "Nowadays any man can write, because there are papers enough to give employment to everybody. No reflection, no deliberation, no care; all is haste, fatal facility, stock phrases, commonplace ideas, and a ready pen that can turn itself to any task with equal ease, because supremely ignorant of all alike." . . . . . . "The writer takes to his craft nowadays, not because he has taste for literature, but because he has an incurable faculty for scribbling. He has no culture, and he soon loses the power of taking pains, if he ever possessed it. But he can talk with glib superficiality and imposing confidence about every conceivable subject, from a play or a picture to a sermon or a metaphysical essay. It is the utter indifference to subject-matter, joined with the vulgar unscrupulousness of pretentious ignorance, that strikes the keynote of our existing criticism. Men write without taking the trouble to read or think."[377] * * * * * The 'Saturday Review' attacked 'Evolution, Old and New,' I may almost say savagely. It wrote: "When Mr. Butler's 'Life and Habit' came before us, we doubted whether his ambiguously expressed speculations belonged to the regions of playful but possibly scientific imagination, or of unscientific fancies; and we gave him the benefit of the doubt. In fact, we strained a point or two to find a reasonable meaning for him. He has now settled the question against himself. Not professing to have any particular competence in biology, natural history, or the scientific study of evidence in any shape whatever, and, indeed, rather glorying in his freedom from any such superfluities, he undertakes to assure the overwhelming majority of men of science, and the educated public who have followed their lead, that, while they have done well to be converted to the doctrine of the evolution and transmutation of species, they have been converted on entirely wrong grounds." . . . . . . "When a writer who has not given as many weeks to the subject as Mr. Darwin has given years [as a matter of fact, it is now twenty years since I began to publish on the subject of Evolution] is not content to air his own crude, though clever, fallacies, but presumes to criticize Mr. Darwin with the superciliousness of a young schoolmaster looking over a boy's theme, it is difficult not to take him more seriously than he deserves or perhaps desires. One would think that Mr. Butler was the travelled and laborious observer of Nature, and Mr. Darwin the pert speculator, who takes all his facts at secondhand." . . . . . . "Let us once more consider how matters stood a year or two before the 'Origin of Species' first appeared. The continuous evolution of animated Nature had in its favour the difficulty of drawing fixed lines between species and even larger divisions, all the indications of comparative anatomy and embryology, and a good deal of general scientific presumption. Several well-known writers, and some eminent enough to command respect, had expressed their belief in it. One or two far-seeing thinkers, among whom the place of honour must be assigned to Mr. Herbert Spencer, had done more. They had used their philosophic insight, which, to science, is the eye of faith, to descry the promised land almost within reach; they knew and announced how rich and spacious the heritage would be, if once the entry could be made good. But on that 'if' everything hung. Nature was not bound to give up her secret, or was bound only in a mocking covenant with an impossible condition: _Si cælum digito tetigeris_; if only some fortunate hand could touch the inaccessible firmament, and bring down the golden chain to earth! But fruition seemed out of sight. Even those who were most willing to advance in this direction, could only regret that they saw no road clear. There was a tempting vision, but nothing proven--many would have said nothing provable. A few years passed, and all this was changed. The doubtful speculation had become a firm and connected theory. In the room of scattered foragers and scouts, there was an irresistibly advancing column. Nature had surrendered her stronghold, and was disarmed of her secret. And if we ask who were the men by whom this was done, the answer is notorious, and there is but one answer possible: the names that are for ever associated with this great triumph are those of Charles Darwin and Wallace."[378] I gave the lady or gentleman who wrote this an opportunity of acknowledging the authorship; but she or he preferred, not I think unnaturally, to remain anonymous. The only other criticism of 'Evolution, Old and New,' to which I would call attention, appeared in 'Nature,' in a review of 'Unconscious Memory,' by Mr. Romanes, and contained the following passages:-- "But to be serious, if in charity we could deem Mr. Butler a lunatic, we should not be unprepared for any aberration of common sense that he might display.... A certain nobody writes a book ['Evolution, Old and New'] accusing the most illustrious man in his generation of burying the claims of certain illustrious predecessors out of the sight of all men. In the hope of gaining some notoriety by deserving, and perhaps receiving a contemptuous refutation from the eminent man in question, he publishes this book which, if it deserved serious consideration, would be not more of an insult to the particular man of science whom it accuses of conscious and wholesale plagiarism [there is no such accusation in 'Evolution, Old and New'] than it would be to men of science in general for requiring such elementary instruction on some of the most famous literature in science from an upstart ignoramus, who, until two or three years ago, considered himself a painter by profession."--'Nature,' Jan. 27, 1881. * * * * * In a subsequent letter to 'Nature,' Mr. Romanes said he had been "acting the part of policeman" by writing as he had done. Any unscrupulous reviewer may call himself a policeman if he likes, but he must not expect those whom he assails to recognize his pretensions. 'Evolution, Old and New,' was not written for the kind of people whom Mr. Romanes calls men of science; if "men of science" means men like Mr. Romanes, I trust they say well who maintain that I am not a man of science; I believe the men to whom Mr. Romanes refers to be men, not of that kind of science which desires to know, but of that kind whose aim is to thrust itself upon the public as actually knowing. 'Evolution, Old and New,' could be of no use to these; certainly, it was not intended as an insult to them, but if they are insulted by it, I do not know that I am sorry, for I value their antipathy and opposition as much as I should dislike their approbation: of one thing, however, I am certain--namely, that before 'Evolution, Old and New,' was written, Professors Huxley and Tyndall, for example, knew very little of the earlier history of Evolution. Professor Huxley, in his article on Evolution in the ninth edition of the 'Encyclopædia Britannica,' published in 1878, says of the two great pioneers of Evolution, that Buffon "contributed nothing to the general doctrine of Evolution,"[379] and that Erasmus Darwin "can hardly be said to have made any real advance on his predecessors."[380] Professor Haeckel evidently knew little of Erasmus Darwin, and still less, apparently, about Buffon.[381] Professor Tyndall,[382] in 1878, spoke of Evolution as "Darwin's theory"; and I have just read Mr. Grant Allen as saying that Evolutionism "is an almost exclusively English impulse."[383] Since 'Evolution, Old and New,' was published, I have observed several of the so-called men of science--among them Professor Huxley and Mr. Romanes--airing Buffon; but I never observed any of them do this till within the last three years. I maintain that "men of science" were, and still are, very ignorant concerning the history of Evolution; but, whether they were or were not, I did not write 'Evolution, Old and New,' for them; I wrote for the general public, who have been kind enough to testify their appreciation of it in a sufficiently practical manner. The way in which Mr. Charles Darwin met 'Evolution, Old and New,' has been so fully dealt with in my book, 'Unconscious Memory;' in the 'Athenæum,' Jan. 31, 1880; the 'St. James's Gazette,' Dec. 8, 1880; and 'Nature,' Feb. 3, 1881, that I need not return to it here, more especially as Mr. Darwin has, by his silence, admitted that he has no defence to make. I have quoted by no means the moat exceptionable parts of Mr. Romanes' article, and have given them a permanence they would not otherwise attain, inasmuch as nothing can better show the temper of the kind of men who are now--as I said in the body of the foregoing work--clamouring for endowment, and who would step into the Pope's shoes to-morrow if we would only let them. FOOTNOTES: [376] See p. 44, and the whole of chap. v., where I say of this supposition, that "nothing could be conceived more foreign to experience and common sense." [377] 'Fortnightly Review,' March 1, 1882, pp. 344, 345. [378] 'Saturday Review,' May 31, 1879, pp. 682-3. [379] P. 748. [380] _Ibid._ [381] See pp. 71-73. [382] 'Nineteenth Century' for November, pp. 360, 361. [383] 'Fortnightly Review,' March, 1882. CHAPTER II. ROME AND PANTHEISM. Evolution would after all be a poor doctrine if it did not affect human affairs at every touch and turn. I propose to devote the second chapter of this Appendix to the consideration of an aspect of Evolution which will always interest a very large number of people--the development of the relation that may exist between religion and science. If the Church of Rome would only develop some doctrine or, I know not how, provide some means by which men like myself, who cannot pretend to believe in the miraculous element of Christianity, could yet join her as a conservative stronghold, I, for one, should gladly do so. I believe the difference between her faith and that of all who can be called gentlemen to be one of words rather than things. Our practical working ideal is much the same as hers; when we use the word "gentleman" we mean the same thing that the Church of Rome does; so that, if we get down below the words that formulate her teaching, there are few points upon which we should not agree. But, alas! words are often so very important. How is it possible for myself, for example, to give people to understand that I believe in the doctrine of the Immaculate Conception or in the Lourdes miracles? If the Pope could spare time to think about so insignificant a person, would he wish me to pretend such beliefs or think better of me if I did pretend them? I should be sorry to see him turn suddenly round and deny his own faith, and I am persuaded that, in like manner, he would have me continue to hold my own in peace; nevertheless, the duty of subordinating private judgment to the avoidance of schism is so obvious that, if we could see a practicable way of bridging the gulf between ourselves and Rome, we should be heartily glad to bridge it. I speak as though the Church of Rome was the only one we can look to. I do not see how it is easy to dispute this. Protestantism has been tried and failed; it has long ceased to grow, but it has by no means ceased to disintegrate. Note the manner in which it is torn asunder by dissensions, and the rancour which these dissensions engender--a rancour which finds its way into the political and social life of Europe, with incalculable damage to the health and well-being of the world. Who can doubt but that there will be a split even in the Church of England ere so many years are over? Protestantism is like one of those drops of glass which tend to split up into minuter and minuter fragments the moment the bond that united them has been removed. It is as though the force of gravity had lost its hold, and a universal power of repulsion taken the place of attraction. This may, perhaps, come about some day in the material as well as in the spiritual and political world, but the spirit of the age is as yet one of aggregation; the spirit of Protestantism is one of disintegration. I maintain, therefore, that it is not likely to be permanent. All the great powers of Europe have from numberless distinct tribes become first a few kingdoms or dukedoms, then two or three nations, and now homogeneous wholes, so that there is no chance of their further dismemberment through internal discontent; a process which has been going on for so many hundreds of years all over Europe is not likely to be arrested without ample warning. True, during the Roman Empire the world was practically bonded together, yet broke in pieces again; but this, I imagine, was because the bonding was prophetic and superficial rather than genuine. Nature very commonly makes one or two false starts, and misses her aim a time or two before she hits it. She nearly hit it in the time of Alexander the Great, but this was a short-lived success; in the case of the Roman Empire she succeeded better and for longer together. Where Nature has once or twice hit her mark as near as this she will commonly hit it outright eventually; the disruption of the Roman Empire, therefore, does not militate against the supposition that the normal condition of right-minded people is one which tends towards aggregation, or, in other words, towards compromise and the merging of much of one's own individuality for the sake of union and concerted action. See, again, how Rome herself, within the limits of Italy, was an aggregation, an aggregation which has now within these last few years come together again after centuries of disruption; all middle-aged men have seen many small countries come together in their own lifetime, while in America a gigantic attempt at disruption has completely failed. Success will, of course, sometimes attend disruption, but on the whole the balance inclines strongly in favour of aggregation and homogeneity; analogy points in the direction of supposing that the great civilized nations of Europe, as they are the coalition of subordinate provinces, so must coalesce themselves also to form a larger, but single empire. Wars will then cease, and surely anything that seems likely to tend towards so desirable an end deserves respectful consideration. The Church of Rome is essentially a unifier. It is a great thing that nations should have so much in common as the acknowledgment of the same tribunal for the settlement of spiritual and religious questions, and there is no head under which Christendom can unite with as little disturbance as under Rome. Nothing more tends to keep men apart than religious differences; this certainly ought not to be the case, but it no less certainly is, and therefore we should strain many points and subordinate our private judgment to a very considerable extent if called upon to do so. A man, under these circumstances, is right in saying he believes in much that he does not believe in. Nevertheless there are limits to this, and the Church of Rome requires more of us at present than we can by any means bring ourselves into assenting to. It may be asked, Why have a Church at all? Why not unite in community of negation rather than of assertion? When I wrote 'Evolution, Old and New,' three years ago, I thought, as now, that the only possible Church must be a development of the Church of Rome; and seeing no chance of agreement between avowed free-thinkers, like myself, and Rome (for I believed Rome immovable), I leaned towards absolute negation as the best chance for unity among civilized nations; but even then, I expressed myself as "having a strong feeling as though Professor Mivart's conclusion is true, that 'the material universe is always and everywhere sustained and directed by an infinite cause, for which to us the word mind is the least inadequate and misleading symbol.'"[384] I had hardly finished 'Evolution, Old and New,' before I began to deal with this question according to my lights, in a series of articles upon God[385] which appeared in the 'Examiner' during the summer of 1879, and I returned to the same matter more than once in 'Unconscious Memory,' my next succeeding work. The articles I intend recasting and rewriting, as they go upon a false assumption; but subsequent reflection has only confirmed me in the general result I arrived at--namely, the omnipresence of mind in the universe. I have therefore come to see that we can go farther than negation, and in this case--a positive expression of faith as regards an invisible universe of some sort being possible--a Church of some sort is also possible, which shall formulate and express the general convictions as regards man's position in respect of this faith. I think the instinct which has led so many countries towards a double legislative chamber, and ourselves, till at any rate quite recently, to a double system of jurisprudence, law and equity, was not arrived at without having passed through the stages of reason and reflection. There are a variety of delicate, almost intangible, questions which belong rather to conscience than to law, and for which a Church is a fitter tribunal--at any rate for many ages hence--than a parliament or law court. There is room, therefore, for both a State and a Church, each of which should be influenced by the action of the other. I do not say that I personally should like to see the Church of Rome as at present constituted in the position which I should be glad to see attained by an ideal Church. If it were in that position I would attack it to the utmost of my power; but I have little hesitation in thinking that the world with a very possible feasible Church, would be better than the world with no Church at all; and, if so, I have still less hesitation in concluding, for the reasons already given, that it is to Rome we must turn as the source from which the Church of the future is to be evolved, if it is to come at all. For the new, if it is to strike deep root and be permanent, must grow out of the old, without too violent a transition. Some violence there will always be, even in the kindliest birth; but the less the better, and a leap greater than the one from Judaism to Christianity is not desirable, even if it were possible. As a free-thinker, therefore, but also as one who wishes to take a practical view of the manner in which things will, and ought to go, I neither expect to see the religions of the world come once for all to an end with the belief in Christianity--which to me is tantamount to saying with Rome--nor am I at all sure that such a consummation is more desirable than likely to come about. The ultimate fight will, I believe, be between Rome and Pantheism; and the sooner the two contending parties can be ranged into their opposite camps by the extinction of all intermediate creeds, the sooner will an issue of some sort be arrived at. This will not happen in our time, but we should work towards it. When it arrives, what is to happen? Is Pantheism to absorb Rome, and, if so, what sort of a religious formula is to be the result? or is Rome so to modify her dogmas that the Pantheist can join her without doing too much violence to his convictions? We who are outside the Church's pale are in the habit of thinking that she will make little if any advances in our direction. The dream of a Pantheistic Rome seems so wild as hardly to be entertained seriously; nevertheless I am much mistaken if I do not detect at least one sign as though more were within the bounds of possibility than even the most sanguine of us could have hoped for a few years back. We do not expect the Church to go our whole length; it is the business of some to act as pioneers, but this is the last function a Church should assume. A Church should be as the fly-wheel of a steam-engine, which conserves, regulates and distributes energy, but does not originate it. In all cases it is more moral and safer to be a little behind the age than a little in front of it; a Church, therefore, ought to cling to an old-established belief, even though her leaders know it to be unfounded, so long as any considerable number of her members would be shocked at its abandonment. The question is whether there are any signs as though the Church of Rome thought the time had come when she might properly move a step forward, and I rejoice to think, as I have said above, that at any rate one such sign--and a very important one--has come under my notice. In his Encyclical of August 4, 1879, the Pope desires the Bishops and Clergy to restore the golden wisdom of St. Thomas Aquinas, and to spread it far and wide. "Vos omnes," he writes, "Venerabiles Fratres, quam enixe hortamur ut ad Catholicæ fidei tutelam et decus, ad societatis bonum, ad scientiarum omnium incrementum auream Sancti Thomæ sapientiam restituatis, et quam latissime propagetis." He proceeds then with the following remarkable passage: "We say the wisdom of St. Thomas. For whatever has been worked out with too much subtleness by the doctors of the schools, or handed down inconsiderately, whatever is not consistent with the teachings of a later age, or finally, is in any way NOT PROBABLE, We in no wise intend to propose for acceptance in these days."[386] It would be almost possible to suppose that these words had been written inadvertently, so the Pope practically repeats them thus: "We willingly and gratefully declare that whatsoever can be excepted with advantage, is to be excepted, no matter by whom it has been invented."[387] The passage just quoted is so pregnant that a few words of comment may be very well excused. In the first place, I cannot but admire the latitude which the Pope not only tolerates, but enjoins: he defines nothing, but declares point blank that if we find anything in St. Thomas Aquinas "not consistent with the assured teachings of a later age, or finally IN ANY WAY NOT PROBABLE"--(what is not involved here?)--we are "in no wise to suppose" that it is being proposed for our acceptance. But it is a small step from allowing latitude in accepting or rejecting the parts of St. Thomas Aquinas which conflict with the assured result of later discoveries to allowing a similar latitude in respect, we will say, of St. Jude; and if of St. Jude, then of St. James the Less; and if of St. James the Less, then surely ere very long of St. James the Greater and St. John and St. Paul; nor will the matter stop there. How marvellously closely are the two extremes of doctrine approaching to one another! We, on the one hand, who begin with _tabulæ rasæ_ having made a clean sweep of every shred of doctrine, lay hold of the first thing we can grasp with any firmness, and work back from it. We grope our way to evolution; through this to purposive evolution; through this to the omnipresence of mind and design throughout the universe; what is this but God? So that we can say with absolute freedom from _équivoque_ that we are what we are through the will of God. The theologian, on the other hand, starts with God, and finds himself driven through this to evolution, as surely as we found ourselves driven through evolution to the omnipresence of God. Let us look a little more closely at the ground which the Church of Rome and the Evolutionist hold in common. St. Paul speaks of there being "one body and one spirit," and of one God as being "above all, and through all, and in you all."[388] Again, he tells us that we are members of God's body, "of his flesh and of his bones;"[389] in another place he writes that God has reconciled us to himself, "in the body of his flesh,"[390] and in yet another of the Spirit of God "dwelling in us."[391] St. Paul indeed is continually using language which implies the closest physical as well as spiritual union between God and those at any rate of mankind who were Christians. Then he speaks of our "being builded together for an habitation of God through the spirit,"[392] and of our being "filled with the fulness of God."[393] He calls Christian men's bodies "temples of the Holy Spirit,"[394] in fact it is not too much to say that he regarded Christian men's limbs as the actual living organs of God himself, for the expressions quoted above--and many others could be given--come to no less than this. It follows that since any man could unite himself to "the flesh and bones" of God by becoming a Christian, Paul had a perception of the unity at any rate of human life; and what Paul admitted I am persuaded the Church of Rome will not deny. Granted that Paul's notion of the unity of all mankind in one spirit animating, or potentially animating the whole was mystical, I submit that the main difference between him and the Evolutionist is that the first uses certain expressions more or less prophetically, and without perhaps a full perception of their import; while the second uses the same expressions literally, and with the ordinary signification attached to the words that compose them. It is not so much that we do not hold what Paul held, but that we hold it with the greater definiteness and comprehension which modern discovery has rendered possible. We not only accept his words, but we extend them, and not only accept them as articles of faith to be taken on the word of others, but as so profoundly entering into our views of the world around us that that world loses the greater part of its significance if we may not take such sayings as that "we are God's flesh and his bones" as meaning neither more nor less than what appears upon the face of them. We believe that what we call our life is part of the universal life of the Deity--which is literally and truly made manifest to us in flesh that can be seen and handled--ever changing, but the same yesterday, and to-day, and for ever. So much for the closeness with which we have come together on matters of fact, and now for the _rapprochement_ between us in respect of how much conformity is required for the sake of avoiding schism. We find ourselves driven through considerations of great obviousness and simplicity to the conclusion that a man both may and should keep no small part of his opinions to himself, if they are too widely different from those of other people for the sake of union and the strength gained by concerted action; and we also find the Pope declaring of one of the brightest saints and luminaries of the Church that we need not follow him when it is plainly impossible for us to do so. Is it so very much to hope that ere many years are over the approximation will become closer still? I have sometimes imagined that the doctrine of Papal Infallibility may be the beginning of a way out of the difficulty, and that its promoters were so eager for it, rather for the facilities it afforded for the repealing of old dogmas than for the imposition of new ones. The Pope cannot, even now, under any circumstances, declare a dogma of the Church to be obsolete or untrue, but I should imagine he can, in council, _ex cathedra_, modify the interpretation to be put upon any dogma, if he should find the interpretation commonly received to be prejudicial to the good of the Church: and if so, the manner in which Rome can put herself more in harmony with the spirit of recent discoveries, without putting herself in an illogical position, is not likely to escape eyes so keen as those of the Catholic hierarchy. No sensible man will hesitate to admit that many an interpretation which was natural to and suitable for one age is unnatural to and unsuitable for another; as circumstances are always changing, so men's moods and the meanings they attach to words, and the state of their knowledge changes; and hence, also, the interpretation of the dogmas in which their conclusions are summarized. There is nothing to be ashamed of or that needs explaining away in this; nothing can remain changeless under changed conditions; and that institution is most likely to be permanent which contains provision for such changes as time may prove to be expedient, with the least disturbance. I can see nothing, therefore, illogical or that needs concealment in the fact of an infallible Pope putting a widely different interpretation upon a dogma now, to what a no less infallible Pope put upon the same dogma fifteen hundred, or even fifteen years ago; it is only right, reasonable, and natural that this should be so. The Church of England may have made no provision for the virtual pruning off of dogmas that have become rudimentary, but the Encyclical from which I have just quoted leads me to think that the Church of Rome has found one, and, in her own cautious way, is proceeding to make use of it. If so, she may possibly in the end get rid of Protestantism by putting herself more in harmony with the spirit of the age than Protestantism can do. In this case, the spiritual reunion of Christendom under Rome ceases to be impossible, or even, I should think improbable. I heartily wish that my conjecture concerning future possibilities is not unfounded. Scientists have been right in preaching evolution, but they have preached it in such a way as to make it almost as much of a stumbling-block as of an assistance. For though the fact that animals and plants are descended from a common stock is accepted by the greater and more reasonable part of mankind, these same people feel that the evidence in favour of design in the universe is no less strong than that in favour of evolution, and our scientists, for the most part, uphold a theory of evolution of which the cardinal doctrine is that design and evolution have nothing to do with one another; the jar they raise, therefore, is as bad as the jar they have allayed. It has been the object of the foregoing work to show that those who take this line are wrong, and that evolution not only tolerates design, but cannot get on without it. The unscrupulousness with which I have been attacked, together with the support given me by the general public, are sufficient proofs that I have not written in vain. FOOTNOTES: [384] P. 371. [385] Published as "God the Known and God the Unknown" in 1909. (Fifield.) [386] "Sapientiam Sancti Thomæ dicimus: si quid enim est a doctoribus scholasticis vel nimia subtilitate quæsitum, vel parum considerate traditum, si quid cum exploratis posterioris ævi doctrinis minus cohærens, vel denique quoque modo non probabile, id nullo pacto in animo est ætate nostra ad imitandum proponi." [387] "Edicimus libenti gratoque animo excipiendum esse quidquid utiliter fuerit a quopiam inventum atque excogitatum." [388] Eph. iv. 3, 4, 5. [389] Eph. v. 30. [390] Col. i. 22. [391] Rom. viii. 2. [392] Eph. ii. 22. [393] Eph. iii. 19. [394] 1 Cor. vii. 19. INDEX ABORTION, neutralization of working bees an act of, 250 Accessory touches, varying Buffon on, 92 Accident, many of our best thoughts come thoughtlessly, 48, 384 ---- profiting by, 51, 53 ---- and discovery of theory connecting meteors with comets, 53 ---- shaking the bag to see what will come out, 53 ---- effects of, transmitted to offspring, Dr. Erasmus Darwin, 224 ---- and design, the line between these hard to draw, 384 Accidental variations thrown for as with dice, 3 Accumulation of variations, C. Darwin deals with the, and not with the origin of, 340, 341 ---- of small divergencies, Buffon on the, 103 Accurate, survival of fittest more accurate than Nat. Sel. and _sometimes_ equally convenient, 9, 354, 365 Act of Parliament, Natural Selection compared to a certain kind of, 358 Age, old, the phenomena of, 67, 204, 381 Aggregation, the spirit of the age tends towards, 397, 398 Ahead, no organism sees very far, 44, 48, 54, 384 Aldrovandus, Buffon on the learned, 93 Alive, when we must not say that an animal is alive (to be retracted), 279 Allen, Grant, on 'Evolution, Old and New,' 386-388 ---- on the decay of criticism, 388 ---- calls Evolutionism "an almost exclusively English impulse," 393 Alternations of fat and lean years, Buffon on, 125 Amoeba, the, did not conceive the idea of an eye and work towards it, 43, 44, 384 Analogies, false, all words are apt to turn out to be, 365 Animals, contracts among, Dr. E. Darwin on, 205 Ape, the, and man, 90 Apes and monkeys, Buffon on, 153 ---- and children fall on all-fours at the approach of danger, 312 Apparentibus, _de non_, _et non existentibus, &c._, 36 Appearances, rather superficial, our only guide to classification, 34, 35, 36, 198, 204 Appetency, Paley's argument against the view that structures have been developed through, 22, 45 Aristides, C. Darwin as just as, 363 Aristotle denied teleology, 4 Artificial and real foot, differences between, 25 Asceticism, virtue errs on the side of excess rather than on that of, 35 Ass, the, and horse, Buffon's pregnant passage on their relationship, 80, 90, 91, 100, 101, 142, 143, 155, 164, 311 Authority, a hard thing to weigh, 253 BACON, F., on evolution, 69 Balzac, quotation from, on memory and instinct, 67 Bark, Erasmus Darwin's theory of, 208 Beaver, trowel incorporated into the beaver's organism, 8 Bees, neutralization of working, an act of abortion, 250 Beetles, Madeira, Lamarck and C. Darwin's views of their winglessness compared, 373, 380 Begin, How could the eye _begin_? 46, 47 Beginnings, of complex structures, a difficulty in the way of natural selection, 21, 22 ---- difficulty of accounting for, 46, 47 ---- a matter of conjecture and inference, 48 Behind, more moral to be behind the age than in front of it, 401 Best, making the best of whatever power one has, 50 Bird, how birds became web-footed, 48, 49, 51 ---- a, will modify its nest a little, under altered circumstances, 55 ---- Buffon on, 170, &c. ---- nests, Dr. Erasmus Darwin's failure to connect the power to make them with memory, 201, 203 ---- aquatic and wading, Lamarck on, 305 Bishop, and Evêque, common derivation of, 355 Blindfolded, we are so far, that we can see a few steps in front, but no more, 44 ---- us, C. Darwin has almost ostentatiously, 346 Blindly, forces interacting blindly, 59 Body and mind, Lamarck on, 338, 339, 341 Brain, Lamarck had brain upon the brain, 36 ---- Buffon on the, 131, 133, &c. Brevity may be the soul of wit, but, &c., 315 Breeding, and feeding, 222 Brown-Séquard, his experiments on guinea-pigs' legs, 303 Buds, individuality of, Dr. Erasmus Darwin on the, 207, 208 Buffalo, Buffon on the, 148, &c. Buffon, profoundly superficial, 34 ---- _plus il a su, plus il a pu, &c._, 44 ---- _dans l'animal il y a moins de jugement que de sentiment_, 51 ---- ignorance concerning, 61 ---- memoir of, 74, &c. ---- on glory, genius, and style, 76, 77 ---- ironical character of his work and method (_see_ Irony), 78, &c., 171 ---- on the ass, horse, and zebra, 80, 90, 91, 100, 101, 142, 143, 155, 164, 311 ---- would not play the part of Rousseau or Voltaire, 81 ---- Sir W. Jardine on, and the Sorbonne, 82 ---- regards all animal and vegetable life as from one common source, 90 ---- if a single species has ever been found under domestication, &c., 91 ---- on plaisanterie, and the learned Aldrovandus, 93, &c. ---- his compromise, 92 ---- accessory touches, 92 ---- "_especially_" the same, 96 ---- fluctuation of opinion an unfounded charge, 97, &c., 164 ---- on the accumulation of small divergencies, 103 ---- began preaching evolution almost on his first page, 104 ---- chapter on the _dégénération des animaux_, equivalent to "on descent with modification," 104, &c. ---- difference of opinion between him and Erasmus Darwin and Lamarck, 105 ---- probably did not differ from Lamarck, 105 ---- on direct action of changed conditions, 105, 145, 147 ---- on man and the lower animals, 108 ---- on classification, 108, 109, 141 ---- on animals and plants, 109, 110 ---- on reason and instinct, 110, 115 ---- on final causes (the pig), 118, &c. ---- on hybridism, 117, 118 ---- rudimentary organs, 120 ---- on animals under domestication, 121, &c., 148 ---- deals with these early, as giving him the best opportunities for illustrating the theory of evolution, 276 ---- approaches natural selection in his "by _some chance_ common enough in Nature," 122 ---- preaching on the hare when he should have preached on the rabbit out of pure love of mischief, 123 ---- resumption of feral characteristics, 123 ---- on the geometrical ratio of increase, 123, &c. ---- alternation of fat and lean years, 125 ---- equilibrium of Nature, 125 ---- "au réel," 126 ---- on violent death, 126 ---- on sensation, 126, &c. ---- on the interaction of organ and sense, 127 ---- the carnivora, 126 ---- his criterion of what name a thing is to bear, 127 ---- his criterion of perception and sensation, 127 ---- on the unity of the individual, 127, 128 ---- satirizes our habit of judging all things by our own standards, 129 ---- the diaphragm, 129 ---- on the stock and the diaphragm, 130 ---- distinction between perception and sensation, 129, 130 ---- on the meninges, 132 ---- on the brain, 131, 133, &c. ---- on scientific orthodoxy and mystification, 138 ---- on the relativity of science, 140 ---- on nomenclature and knowledge, 141 ---- on the genus _felis_, 143 ---- on the lion and the tiger, 143, 145 ---- on the animals of the old and new world, 145, &c. ---- on changed geographical distribution of land and water, 145, 164 ---- on extinct species, 146 ---- hates the new world, 146 ---- on heredity and habit, 148, 159, 160, 161, 162 ---- approaches Erasmus Darwin and Lamarck, _re_ the Buffalo, Camel, and Llama, 148, 160, 161 ---- on oneness of personality between parents and offspring, 151 ---- on the organic and inorganic, 153, &c. ---- on apes and monkeys, 153, &c. ---- on the causes or means of the transformation of species, 159, &c. ---- on generic (as well as specific) differences, 164 ---- on plants under domestication, 167 ---- on pigeons and fowls, 169 ---- on birds, 170, &c. ---- the assistance he rendered to Lamarck, 237, 258 ---- Isidore Geoffroy's failure to understand, 328 ---- Colonel, 75 Bulk, a _sine quâ non_ for success in literature or science, 315 Bull running, Tutbury, and Erasmus Darwin, 187 CAMEL, Buffon on the hereditary ills of the, 161 Cant, and rudimentary organs, 38 Captandum, all good things are done ad, 85 Carnivora, Buffon on the, 126 Carriage, Dr. Erasmus Darwin's, 181 Cat, family, Buffon on the, 142, &c. ---- with a mane and long tail, 143 Cataclysms, the good cells that get exterminated during the cataclysms of our own development, 75 Catastrophes, Lamarck on, 277 Causes, or "means," of modification, 301 ---- C. Darwin says that Buffon has not entered on the, 104, &c. ---- C. Darwin gets us into a fog about, 345, &c. Change, under changed circumstances, Mr. Patrick Matthew on, 318 Charity, the greatest of these is, 77 Church, a, like a second chamber, 400 ---- the world better with than without, 400 ---- should be like the fly-wheel of a steam engine, 104 _Circonstances_ (_see_ Conditions of Existence), Lamarck on, 268, 281 Circumstance, suiting power, a, Mr. Patrick Matthew on, 318-321 Classification, rather superficial appearances our best guide to, 34, 35, 36, 198, 204 ---- Buffon on, 108, 109, 141 Clear, an ineradicable tendency to make things, 92 Clifford, Professor, on "Design," 6, 7 Climbing plants, the movements of, Dr. Erasmus Darwin on, 209 Coherency, the persistency of ideas the best argument in support of their legitimate connection, 23 Coleridge, on "Darwinising," 21 Common terms, our, involve the connection between memory and heredity, 201, 205 ---- descent, the "hidden bond" of Lamarck, as also of C. Darwin, 271 Comparative anatomy, Lamarck on, 266, &c. Complex structures, the incipiency of, a difficulty in the way of the natural selection view of evolution, 21, 22 Compromise, Buffon's, 92 Conditions of existence, the very essence of condition involves that there shall be penalty in case of non-fulfilment, 352, 376, 377 ---- and the winglessness of Madeira beetles, 373, &c. ---- according to C. Darwin, "include" and yet "are fully embraced by" natural selection, 355 ---- identical with "natural selection," 351-354 ---- Étienne Geoffroy, and Lamarck on, 326, 327, 328 ---- Buffon on the, 103; difference between Buffon's and Lamarck's view of their action, 105 ---- direct action of changed, Buffon on the, 145, 147, 160 ---- Lamarck on, 105, 268, 270, 271, 275, 277, 278, 281, 291, 292, 294, 295, 298, 299, 300, &c. Continuity in discontinuity, and _vice versâ_, 47 Contracts of animals, Dr. E. Darwin on the, 205 Contrivance, does organism show signs of this? 2 Convenient, not only _sometimes_, but always, more, 365 Corkscrew for corks, and lungs for respiration, Prof. Clifford on, 7. See also p. 58 ---- we should have grown a, if drawing corks had been important to us, 7 Creator, a, who is not an organism, unintelligible, 6, 11, 24 Criticising, difficulty of, without knowing more than the mere facts which are to be criticised, 172 Criticism, Miss Seward's, on Dr. Darwin's "Elegy," 189 ---- Grant Allen on the decay of, 388 Crux, the, of the early evolutionist, 35 Cuttle-fish, natural selection like the secretion of a, 332 DAMNATION, praising with faint, 111 Darwin, Charles, on the eye, denies design, 8 ---- declares variation to be the cause of variation, 8, 347, 369 ---- and blind chance working on whither; the accumulation of innumerable lucky accidents, 41, 42 ---- our indebtedness to, 62, 66, 335 ---- has adopted one half of Isidore Geoffroy's conclusion without verifying either, 83 ---- on Buffon's fluctuation of opinion, 97 ---- on Isidore Geoffroy, 97 ---- his assertion that Buffon has not entered on the "causes or means" of transformation, 104 ---- his meagre notice of his grandfather, 196 ---- his treatment of the author of the "Vestiges of Creation," 65, 247, 248 ---- attributes the characteristics of neuter insects to natural selection, 249 ---- his treatment of Lamarck, 249, 250, 251, 298, 314, 376 ---- "great is the power of steady misrepresentation," 251 ---- his "happy simplicity" about animals and plants under domestication, 276 ---- his notice of Mr. Patrick Matthew in the imperfect historical sketch which he has prefaced to the "Origin of Species," 315, 316 ---- points of agreement between him and Lamarck, 335-337 ---- sees no broad principle underlying variation, 339 ---- dwells on the accumulation of variations, the origination of which he leaves unaccounted for, 340, 341 ---- his variations being due to no general underlying principle, will not tend to appear in definite directions, nor to many individuals at a time, nor to be constant for long together, 342 ---- speaks of natural selection as a cause of modification, while declaring it to be a means only, 345, &c. ---- his explanation of this, 384, &c. ---- his dilemma, as regards the "Origin of Species," 346 ---- declares the fact of variation to be the cause of variation, 8, 347, 369 ---- if he had told us more of what Buffon, &c., said, and where they were wrong, he would have taken a course, &c., 357 ---- on the ease with which we can hide our ignorance under a cloud of words, 358 ---- apologizes for having underrated the frequency and importance of variation due to spontaneous variability, 358 ---- his "Origin of Species" like the opinion of a lawyer who wanted to leave loopholes, or an Act of Parliament full of repealed and inserted clauses, 358 ---- accused of confusion and inaccuracy of thought, 359 ---- as just as Aristides himself, 364 ---- most candid literary opponent in the world, 364 ---- declares Nature to be the most important means of modification, and variation to be the cause of variations, 369 ---- like a will-o'-the-wisp, 372 ---- disuse, the main agent in reducing wings of Madeira beetles, 377 ---- how he and Lamarck treat the winglessness of Madeira beetles respectively, 373-380 ---- an example of his "manner," 378 ---- the way in which he met "Evolution, Old and New," 393 Darwin, Erasmus, never quite recognized design, 39 ---- ignorance concerning, 61 ---- on reason and instinct, 115, &c. ---- life of, 173, &c. ---- in Nottingham market-place, 182, 184, 197 ---- and Dr. Johnson, 184, 185 ---- and Tutbury bull running, 187 ---- his poetry about the pump, and illustration, 84, 193 ---- should have given his evolution theory a book to itself, 197 ---- had no wish to see far beyond the obvious, 197 ---- must be admitted to have missed detecting Buffon's humour, 83, 84, 197 ---- did not attribute instincts and structures to memory pure and simple, 198 ---- on the reasoning powers of animals, and on instinct, 201, 205 ---- his failure to connect memory and instinct, as with birds' nests, 201-203 ---- failed to see the four main propositions which I contended for in "Life and Habit," 37, 203, 204 ---- on the analogies between animal and vegetable life, 206, &c. ---- on sensitive plants, 206, 210 ---- on the individuality of buds, and his theory of bark, 207, 208 ---- on the movements of climbing plants, 209 ---- on the oneness of personality between parents and offspring, 214; the embryo not a new animal, 215 ---- on animals under domestication, 223 ---- on the effects of accidents transmitted to offspring, 224 ---- sees struggle, and hence modification, turn mainly round three great wants, 226, 229, 257, 279 ---- on desire as a means of modification, 226, 228, 259 ---- by a slip approaches the error of his grandson, 227, 228 ---- on embryonic metamorphoses, 230, 231 ---- believed animals and plants to be descended from a common stock, 233 ---- and Lamarck compared, 257 ---- on the struggle of existence, and the survival of the fittest, 227, 232, 259 Darwin, Mrs. Erasmus, death-bed of, 178 Darwin, Francis, mentioned, 109 ---- his interesting lecture, 206 ---- does not use the expression "natural selection," 368 Darwinising, Coleridge on, 21 Darwinism, the old Darwinism involves desire, invention, and design, 58 ---- modern, falling into disfavour, 60 ---- and evolution not to be confounded, 360, 361 Day, the portrait of, by Wright of Derby, 180 Death, violent, Buffon on, 126 ---- of Dr. Erasmus Darwin, 193, 194 Death-bed of Mrs. Erasmus Darwin, 178 Deed, illustration drawn from a very intricate, 28 Definite, with Lamarck the variations are, 341, 344 _Dégénérations_, 87 Demand and supply, like power and desire, 222, 300 Demonstrative case, "this demonstrative case of neuter insects, &c.," 249, 298, 314 Descent, with modification, spoken of as though synonymous with natural selection, 248, 356 Design, and organism, shall we or shall we not connect these ideas? 2 ---- Aristotle denied, Plato upheld, Haeckel on, 4 ---- Prof. Clifford's denial of, 6, 7 ---- does certainly involve a designer who has an organism, who can think, and make mistakes, 6, 24 ---- a belief in both design and evolution, commonly held to be incompatible, 9 ---- Sir W. Thomson and Sir J. Herschel on, 11 ---- Paley on, 12, &c. ---- light thrown by embryology on the method of, 25 ---- G. H. Lewes opposes, 26 ---- the three positions in respect to, taken by Charles Darwin, Paley, and the earlier evolutionists, 31 ---- the first evolutionists did not see that their view of evolution involved design, 34 ---- from within as much design as from without, 36 ---- was equivalent to theological design, with the early evolutionists, 36 ---- if each step is taken designedly, the whole is done designedly, 52, 384 ---- and accident, the line between them hard to draw; shaking the bag, &c., 53, 384 ---- instinct originated in, 54 ---- as much lost sight of with old-established forms of the steam-engine as with birds' nests or the wheel, 55 ---- Dr. E. Darwin's failure to see that evolution involves design, 195 ---- we feel the want of, as much as we do of evolution, 407 ---- evolution not only tolerates, but cannot get on without, 408 Designer, "I believe in an organic and tangible designer of every complex structure," 6 ---- "where is he? show him to us," &c., 29, 30 ---- the, of any organism, the organism itself, 30, 31, 40 Desire and power, interaction of, 44, 45, 47, 127, 217, 221, 300, 322 ---- and power, like wealth, 222 ---- as a means of modification, Dr. Erasmus Darwin on, 226, 228, 259 Development, the history of organic, the history of a moral struggle, 45 ---- always due to making the best of the present, 50 Devils, 20,000, dancing a saraband on the point of a needle, 216 Dew drop, or lens, the, and Lord Rosse's telescope, 44, 47 Diaphragm, Buffon on the, 129 Dice, accidental variations thrown for as with, 3 Difference between animal and ordinary mechanism, 24 ---- the main, between the manufacture of tools and that of organs, 39 Dilemma, C. Darwin's, 346 Direct action of changed conditions, Buffon on the, 105, 145, 147, 160 Discontinuity in continuity, 47 Disease, accidents followed by, 303 Disintegration, Protestantism tends towards, 397 Distribution, geographical, changed, Buffon on, 145, 164 Disuse, and the winglessness of Madeira beetles, we are almost surprised to find that they are connected at all, 375 ---- the main agent in reducing the wings of Madeira beetles, 377 ---- some examples of the effect of, adduced by Lamarck, 378 Dog, Buffon on the, 120 ---- Lamarck on the various breeds of the, 297 Domestication, a single case of a species formed under domestication sufficient to remove the _à priori_ difficulty from a comprehensive theory of evolution, 90, 91, 311 ---- plants under, Buffon on, 167, &c. ---- Buffon on animals under, 103, 120, &c., 148, &c., 159, &c., 276 ---- animals under, Dr. Erasmus Darwin on, 223 ---- animals under, Buffon on, 121, &c., 148, 276 ---- C. Darwin on, 276 ---- animals and plants under, Lamarck on, 275, 293, 296, 297, 300 ---- animals and plants under, Mr. Patrick Matthew on, 324 Door, the doing anything well will open the door for doing something else, 51 Ducks, our domesticated, why they cannot fly like wild ones, 296, 309 EARN, "you are but doing your best to earn an honest living," 29 Ears are never found in a rudimentary condition, 379 Eat, or be eaten, 177 Effort, Paley's argument that structures have not been developed through, 22, 45 ---- too much, as vicious as indolence, 35 ---- "neither too much nor too little," 50 ---- Herculean, condemned, 197 Egyptian mummies, Lamarck on, 274, 275 Embryology, the light it throws upon the mode in which organisms have been designed, 25 Embryonic metamorphoses, Erasmus Darwin on, 230, 231 Embryonic development, Lamarck on, 289 Encyclical, the Pope's, on St. Thomas Aquinas, 402, &c. Endeavour, Paley's argument against the view that structures have been developed through, 22, 45 Endowment, the new orthodoxy, which is clamouring for, 360 English wines, Dr. Erasmus Darwin's preference for, 175 Environment. _See_ Conditions of Existence Equilibrium, the, of Nature, Buffon on the, 125 Err, the power to, rated highly, 29 ---- "it is on this margin that we may err or wander," 50 ---- virtue ever errs on the side of excess, 35 Error, importance of, dependent on the distance, rather than the direction, 50 "Especially" the same, 92, 96 Ethiopian, the, can change his skin, if it becomes worth his while to try long enough, 40 Evêque and bishop, common derivation of, 355 Everlasting, God, how far, 32 Evolution, commonly held incompatible with design, 9 ---- Paley, its first serious opponent in England, 21 ---- Sir Walter Raleigh on, 21, 70 ---- must stand or fall according as it rests on a purposive foundation or no, 60 ---- brief summary of its six principal stages, 62, &c. ---- Bacon on, 69 ---- the theory of, as apart from the evidence in support of it, 332 ---- C. Darwin and Lamarck are equally intent upon establishing the same theory of evolution, 335-337 ---- and Darwinism, not to be confounded, 360, 361 ---- Rome and Pantheism meet in, 403 Evolutionists, the early, did not know that they accepted teleology, 34 ---- the early, saw design, only as design by the God of theologians, 36 Experience and instinct, Mr. Patrick Matthew on, 322 Extinct species, Lamarck on, 277 ---- Buffon on, 146, 277 Eye, no creature that had nothing like an eye ever set itself to conceive one and grow one, 44, 387 ---- Paley asks "how will our philosopher get an eye?" 46 ---- of flat fish, Lamarck on the, 307 ---- Lamarck on the, of underground and cave-inhabiting animals, 378 ---- disappear and reappear in the scale of organism according to the power of using them, 379 FAITH, forms of, or faiths of form, &c., 339 Familiarity, with a little, such superficial objections will be forgotten, 367 Far ahead, no organism ever saw an improvement a long way off and made towards it, 43, 44, 48, 49, 54, 384 Father, the man who could be father of such a son and retain his affection, &c., 76 Factors, there have been two, of modification, one producing and the other accumulating variations, 227 Fecundity, alternate years of, Buffon on, 125 Feeding and breeding, 222 Feel, if plants and animals look as if they feel, let us say they feel, 198 Feeling, there is more feeling than reason in animals, 51 Feral characteristics, resumption of, Buffon on, 123 Final causes, the doctrine of, as commonly held in the time of the early evolutionists, 34, 36 ---- Buffon on, 118, &c. Fitness, the cause of, more important than the fact that fitness is commonly fit, and therefore successful, 351 Flat fish, Lamarck on the eyes of, 307 Fluctuation of opinion, C. Darwin on Buffon's, the charge refuted, 97, &c., 164, 166 Fontenelle, on theories, 22 Foot, and model of foot, differences between, 24 Forms of faith, or faiths of form, &c., 339 Four main points which the early evolutionists failed to see in their connection and bearing on each other, 37, 203 Four main principles, the, which I contended for in "Life and Habit," 37, 203, 380, 381 Fowls and pigeons, Buffon on, 169 GARNETT, Mr. R., and "Darwinising," 21 Genius, Mr. Allen says I am a, 388 Gentleman, the Church of Rome means the same by the word as we do, 395 Geoffroy, Étienne, how small a way he goes, 196 ---- and Isidore, trimmers, 328 ---- on Buffon, 328 ---- on conditions of existence, 326, 327 ---- declares against Lamarck's hypothesis, 328 ---- his position, 325-328 Geoffroy, Isidore, on evolution and final causes, 9 ---- on Buffon's fluctuation of opinion, 98, &c., 164, 166 ---- points out the difference between the views of Buffon and Lamarck, 105 ---- statement that Buffon's opinions fluctuated again refuted, 166 ---- and Lamarck's hypothesis, 244-246, 329 ---- on Buffon, 328 ---- his position, 329 Genealogical order, Lamarck on, 264 ---- C. Darwin on, 265 Generation more remarkable than reason, Hume on, 233 Generic differences (as well as specific), Buffon on, 164 Genius, a supreme capacity for taking pains, 76 Geographical distribution, changed, Buffon on, 145, &c., 164 Geometrical ratio of increase, Buffon on, 123 ---- Lamarck, on, 280 ---- Patrick Matthew on, 320, 321 Germ of oak indistinguishable from that of a man, 334 Germans, Buffon on the, 93 Glory "comes after labour if she can," &c., 76 Go away, because their uncles, aunts, 376 God, embodied in living forms, and dwelling in them, 31 ---- how far everlasting, invisible, imperishable, omnipotent, &c., 32 ---- the unseen parts of, are as a deep-buried history, 33 Goethe, as an evolutionist, 71 Gradations infinitely subtle, 87 Grant Allen, on "Evolution, Old and New," 386-388 ---- on the decay of criticism, 388 ---- says that "Evolutionism is an almost exclusively English impulse," 393 Greyhound or racehorse, the well-adapted form of the, 359 Growth attended at each step by a felicitous tempering of two antagonistic principles, 35 Gueneau de Montbeillard, 172, 173 HABIT," "Life and. _See_ "Life and Habit." ---- rudimentary organs repeated through mere force of, 38, 39 ---- Buffon on, 148, 159, 160, 161, 162 ---- a second Nature, Lamarck on, 300 Habits, or use, and organ, Lamarck on the interaction of, 292, 311 Haeckel, on design, 4, 5 ---- on Goethe as an evolutionist, 71 ---- does not appear to know of Buffon as an evolutionist, 71, 393 ---- his surprising statement concerning Lamarck, 73 ---- his ignorance concerning Erasmus Darwin, 73, 393 ---- on Lamarck, 246, 247 ---- A. R. Wallace's review of his "Evolution of Man," 382, 384 Hamlet, the "Origin of Species" like "Hamlet" without Hamlet, 363 Handiest, a man should do whatever comes handiest, 51, 52 Hare, Buffon on the, 123, &c. Hartmann's philosophy of the unconscious, and "Life and Habit," 56, 57 Hearing, when we once reach animals so low as to have no organ of, we lose this organ for good and all, 379 Heredity and habit, Buffon on, 148, 159, 160, 161, 162 ---- only another term for unknown causes, unless the "Life and Habit" theory be adopted, 384 Hering, Professor, referred to, 66, 67 ---- his theory as given in "Nature" by Ray Lankester, 198-200 Herschel, Sir John, compares natural selection to the Laputan method of making books, 10 Higgling and haggling of the market, 50 History of the universe, each organism is a, from its own point of view, 31 Horse and ass, Buffon's most pregnant passage on the, 80, 90, 91, 100, 101, 142, 143, 155, 164, 311 ---- and man, skeleton of the, 88, 89 ---- and zebra, Buffon on the, example of irony, 80, 155, 164 Hume, his saying that generation is more remarkable than reason, 233 Huxley, Professor, referred to, 93 ---- pointed out to Professor Mivart the difficulty in the way of natural selection, 344 ---- his ignorance concerning the earlier history of evolution, 392, 393 Hybridism, Buffon on, 117, 118 Hybrids, sterility of, Lamarck on, and C. Darwin on, 272, 273 IDEAS, the bond or nexus of our, 23, 29, 30 Ignorance, the prevailing, concerning the earlier evolutionists, 61 ---- it is easy to hide our, under such expressions as "plan of creation," or natural selection, 358 Imitation, instinct not referable to, as maintained by Erasmus Darwin, 202 Immutability of species and design commonly accepted together, 9, 10 Improvements, small successive, in man's inventions, 44, 46, 47, 54, 55, 384 Inaccuracy of thought, C. Darwin accused of, 359 Incipiency, of complex structures, a difficulty in the way of the Natural selection view of evolution, 21, 22 Incorporate, the designer is, with the organism, 30 Increase, geometrical ratio of Buffon on the, 123 ---- Lamarck on, 280 ---- Patrick Matthew on, 320, 321 Indefinite, with C. Darwin the variations are, 342, 344 Indifference, I say I am more indifferent than I think I am, whether mind is or is not the least misleading symbol for the cause that sustains the universe, 371 Indirect action of conditions of existence according to Lamarck, 294, 299, 306. (_See_ "Conditions of Existence") Individuality, Buffon on, 128 ---- of buds, Erasmus Darwin on the, 207, 208 ---- our, a _consensus_, or full-flowing river, 318 Infallibility, possible results of the doctrine of Papal, 406 Insectivorous plants, Erasmus Darwin on, 206 Instep, ligament that binds the tendons of the, Paley on the, 22 Instinct, present, does not bar its having arisen in reason and reflection, 53, 54 ---- returns to its earlier phase, _i. e._ to reason on the presence of the unfamiliar, 54, 55, 56 ---- and reason, Buffon on, 110-116 ---- Darwin, Erasmus, on, 115, 116, 204 ---- not referable to imitation, as maintained by Erasmus Darwin, 202 ---- is reason become habitual, 203 ---- reason perfected and got by rote, 256 ---- and reason, Lamarck on, 256, 257, 274 ---- referred to experience and memory, by Patrick Matthew, 322 Insult, "Evolution, Old and New," not intended as an insult to men of science, 392 Interaction of want and power, 44, 45, 47, 217, 218, 221, 300, 323 ---- of body and mind, Lamarck on the, 338, 339, 341 Interesting, the more interesting the animal the more evolution Buffon puts into his account of it, 84 Intermediate forms, Lamarck on, 283, 286 ---- C. Darwin, 284, 285 Inventions, small successive improvements in man's, and development of, analogous to that of organism, 44, 46, 47, 54, 55, 384 Irony, good-natured and the reverse, 91 ---- an apology for, and explanation how far it is legitimate, 111, 112 ---- Buffon's, 78, &c., 91, 92, 93, 155, 157, 163, 164 JARDINE, Sir W., on Buffon's character, 82 Johnson, Dr., and Erasmus Darwin, 184, 185 Joints, Paley on the human, 19, 20 Juggle, Paley's argument a juggle, unless man has had a _bonâ fide_ personal, and therefore organic designer, 14, 16 KNEE-PAN, Paley on the human, 18 Knowledge, nomenclature mistaken for, 141 LABOUR, glory comes after, if she can, 76 Lamarck, had brain upon the brain, 36 ---- never quite recognized design, 39 ---- Haeckel's surprising statement concerning, 73 ---- wherein he mainly differs from Buffon, 105 ---- memoir of, 235 ---- his connection with Buffon, as tutor to his son, &c., 237, 258 ---- his daughters, 242, 253 ---- his poverty and blindness, 242, 253 ---- Isidore Geoffroy on, bad caricature of his teaching, 244-246 ---- Haeckel on, 246, 247 ---- never seriously discussed, 247 ---- "the well-known doctrine of," C. Darwin's reference to, 249, 250, 251, 298, 314, 376 ---- on the opposition his theory met with, 252 ---- too old to have begun his unequal contest, 253 ---- on the feeling of animals, 254, 255 ---- too theory-ridden, 254 ---- misled by Buffon (query), 255 ---- took from Buffon without sufficient acknowledgment, 255, 258, 260, 311 ---- as compared with Dr. Erasmus Darwin, 257 ---- like Dr. E. Darwin, sees struggle and modification turn mainly round three great wants, 257, 279, 300, 309 ---- when and how he came over to the side of mutability, 258 ---- and the French translation of the "Loves of the Plant," 259 ---- on comparative anatomy, 266 ---- on species, 267, &c. ---- on conditions of existence (_circonstances_), 105, 268, 270, 271, 275, 277, 278, 281, 291, 292, 294, 295, 298, 299, 300, &c. ---- on instinct, 274 ---- on animals and plants under domestication, 275, 293, 296, 297, 300 ---- on extinct species, 277 ---- anticipated Lyell in rejecting catastrophes, 277 ---- on the geometrical ratio of increase and struggle for existence, 280-282 ---- on embryonic development, 289 ---- the main principles which he supposes to underlie variations, 292, 299, 338, 339 ---- his contention that plants have neither actions nor habits, 295 ---- on use and disuse, 294, 296, 299, 301, 302, 304, 305, 307-309 ---- on the various breeds of the dog, 297 ---- habit a second nature, 300 ---- like Erasmus Darwin and Buffon, understood the survival of the fittest, 301 ---- on the way in which serpents have lost their legs, 303 ---- on wading and aquatic birds, 305 ---- on the eyes of flat fish, 307 ---- on man, 311, &c. ---- on a single instance of considerable variation under domestication, 311 ---- on speech, 313, 314 ---- on the upright position of man and certain apes, 313 ---- his, and Étienne Geoffroy's views on conditions of existence, 326, 327, 328 ---- his hypothesis, and Isidore Geoffroy, 329 ---- Herbert Spencer on, 330, 331 ---- desired to discover the law underlying variations, 337 ---- the extent to which he and C. Darwin take common ground, 335-337 ---- on body and mind, 338, 339, 341 ---- on his theory variations will be definite, will appear in large numbers of individuals at the same time, for long periods together, 341 ---- how he and C. Darwin treat the winglessness of Madeira beetles respectively, 373-380 ---- on the eyes and ears of cave-inhabiting animals, 378, 379 Laputan method of making books, the, and natural selection, 11 Lawyer's deed, if we come across a very intricate, &c., 27 Leopard, the, can change his spots if it becomes worth his while to try long enough, 40 Lewes, G. H., on embryology, 25 ---- his objection to the tentativeness with which the same errors are repeated generation after generation, 26 ---- his objection to C. Darwin's language concerning natural selection, 346 Lewes, G. H., on natural selection, 348, 349, 359 Life, some remarks about the criterion of, that I must retract, 279 ---- one Proteus principal of, 320 "Life and Habit," what I believe to have been its most important features, 67, 203, 204 ---- recapitulation of the main principle insisted on, 37, 56, 203, 380, 381, 384 ---- and Hartmann's philosophy of the unconscious, German review, 56, 57 Lifetime, considerable modifications effected during a single, 304 ---- the changes undergone by organisms during a single, Herbert Spencer, on, 332-334 Ligament, the, which binds down the tendons of the instep, 21 Living, Paley is but doing his best to earn an honest, 29 ---- forms of faith, or faiths of form, 339 Lines, no sharp can be drawn, 47 Lion and tiger, Buffon on the, 143, 145 Llama, Buffon on the hereditary ills of the, 161 Longevity, the principle underlying, 67, 380, 381 Loopholes for escape, the "Origin of Species" full of, 358 "Loves of the Plants," French translation of the, 63, 259 Lungs for respiration, and corkscrew for corks, Professor Clifford on, 7. (_See_ also p. 58) Lyell, Sir C., and Lamarck, 277 ---- on the similarity between Lamarck's theory and Mr. Darwin's, 336, 337 MACHINE, Paley declares animals to be neither wholly machines nor wholly not machines, 14 Madeira beetles, the ways in which Lamarck and C. Darwin would treat their winglessness, 373-380 Maillet, de, referred to, 70 Mainspring, the true, of our existence lies not in these muscles, &c., 32 Man, the designer of man, 30 ---- and horse, skeleton of the, 88, 89 ---- and the ape, 90 ---- and the lower animals, Buffon on, 107, 108 ---- Lamarck on, 311, &c. Manner, the, is the man himself, 77 ---- "but this is Mr. Darwin's", 378 Manufacture, the, of tools and of organs, two species of the same genus, 39 Margin, there is a margin in every organic structure, &c., 49, 50 ---- on the margin of the self-evident the greatest purchase is obtainable, 197 Market, the higgling and haggling of the, 50 Martins, M., his life of Lamarck, 235, &c. Matter less important than the manner, 77 ---- and mind, inseparable, 371 Matthew, Mr. Patrick, his work on naval timber and arboriculture, 64, 65 ---- extracts from, 315, &c. ---- Mr. C. Darwin on, 315 ---- on animals and plants under domestication, 324 ---- on will as influencing organism, 320, 321, 322 ---- on the struggle for existence with survival of the fittest, 320, 322 ---- and natural selection, 323 ---- on instinct and memory, and on the continued personality of parents in offspring, 321, 322, 323 Means, C. Darwin's dangerous use of this word, 345 ---- one _sine quâ non_ for a thing is as much a means of that thing's coming about as anything else is, 349 Mechanism of animals, Paley on the, 14 Mechanism of animals, evidence of design in any ordinary, 15 Memory, and life and heredity, 37, 38, 39, 56, 67, 198-203, 332, 380, 381 ---- Professor Hering on, 198-200 ---- Patrick Matthew on, 322 Meteoric, both want and power are, 44, 45 Meninges, Buffon on the, 132 Microcosm, each organism a history of the universe from its own point of view, 31 Microscope, illustration from successive improvements in the, 46, 47 Mind, "the least inadequate and misleading symbol," for the power that has designed organism, 3, 371 ---- and body, Lamarck on, 338, 339, 341 ---- and matter inseparable, 371 Misfortune, take advantage of, 51 Misrepresentation, "great is the power of steady," 251 Missionaries should avoid trying to effect sudden modifications, 183 Mistake, the power to make, rated highly, 29 ---- importance of, depends on magnitude rather than on the direction, 50 Mivart, Professor, says that, "Mind is the least adequate and misleading symbol," &c., 3, 371 ---- referred to, 22, 66, 67 ---- admits that his objection does not tell against the Lamarckian theory of evolution, 343 ---- points out that the admission of a principle underlying variations is fatal to C. Darwin's theory concerning natural selection, 343 ---- on C. Darwin's "haphazard, indefinite variations," 343 ---- how Professor Huxley pointed out to him the objection to C. Darwin's theory concerning natural selection, 344 ---- asks what is natural selection? and declares it to be repudiated by its propounder, 369 ---- declares it to be "nothing," and a puerile hypothesis, 370, 371 ---- declares the causes of variation to be the causes of the distinction of species, 370 Model, artificial, of a foot, and true foot, difference between, 24 Modification. It is only on modification that reason reasserts itself, 55 ---- there have been two factors of, one producing variations, and the other accumulating them, 227 ---- arrived at by struggle round three great wants, Erasmus Darwin on, 226-229 ---- Lamarck on the same, 257, 279, 300, 301 ---- the cause of survival, not survival the cause of modification, 302 Moral, an organism is most, when looking a little ahead, but not too far, 44 ---- struggle, the history of organic development, the history of a, 45 ---- more, and safer, to be behind the age than in front of it, 401 Movement, Buffon's great criterion of sensation, 127 Mummies, Egyptian, Lamarck on, 274, 275 Murphy, Rev. J. J., mentioned, 22 ---- referred to, 66, 67 Mutability of species commonly held to be incompatible with a belief in design, 9, 10 Mystery-mongering, that Buffon wished to protest against, 81, 171 Mystification, scientific, and orthodoxy, Buffon on, 138 NAIVELY, as Mr. Darwin naively adds, "_sometimes_ equally convenient," 354 Natural selection, the essence of the theory is that the variations shall have been mainly accidental, 7 Natural selection, the unerring skill of, 9 ---- Sir William Thomson and Sir John Herschel on, 10 ---- Button, and, "by _some chance_ common enough with Nature," 122 ---- spoken of as though synonymous with descent with modification, 248, 285, 356 ---- C. Darwin attributes the instincts of neuter insects to, 249 ---- Mr. Patrick Matthew and, 323 ---- like the secretion of a cuttle-fish, 332 ---- G. H. Lewes's objection to C. Darwin's language concerning, 346 ---- if this is declared to be a cause, the fact of variation is declared to be the cause of variation, 347 ---- declared by C. Darwin to be a means of variation, 347 ---- treated as a cause, 348 ---- G. H. Lewes on, 348, 349, 350 ---- identity with "conditions of existence," 351-354 ---- according to C. Darwin, "fully embraces" and yet "is included in" conditions of existence, 355 ---- a cloak for want of precision of thought, and of substantial difference from Lamarck, 358 ---- "some have even imagined that it induces variability;" and small wonder, considering C. Darwin's language concerning it, 362 ---- C. Darwin's reply to those who have objected to the term, 362-368 ---- a cloak of difference from C. Darwin's predecessors, under which there lurks a concealed identity of opinion as to main facts, 362, 363 ---- "implies only the preservation of such variations as arise," &c., 363 ---- admitted by C. Darwin to be a false term, 364 ---- the complaint is that the expression has been retained when an avowedly more accurate one is to hand, 365, 366 ---- only another way of saying Nature, 368, 369 ---- the dislike of it is increasing, 368, 369 ---- Francis Darwin does not use the expression, 368, 369 ---- daily and hourly scrutinizing throughout the world, &c., 369 ---- practically repudiated by C. Darwin himself, 369 ---- Professor Mivart declares it to be "simply nothing," 370 ---- a "puerile hypothesis," 371 ---- and not disuse, the true main cause of the winglessness of Madeira beetles, according to C. Darwin, 374 ---- _not_ the main cause of the winglessness of Madeira beetles, according to C. Darwin, 377 ---- "combined probably with disuse," will account, according to C. Darwin, for the winglessness of Madeira beetles, 375 _Naturalistes_, _le peuple des_, 80, 171 Nature, the personification of comparatively venial, 367 ---- and natural selection the same thing, 368, 369 ---- the most important means of modification, and variation the cause of variation, 369 Neck, Paley on the human, 17, 18 Need, sense of, the main idea in connection with evolution that is left with the reader by the "Zoonomia," or "Philosophie Zoologique," 363 Needle, 20,000 devils dancing a saraband on the point of a, 216 Nest, a bird will alter its nest a little, to meet altered circumstances, 55 Nests, birds', Dr. E. Darwin on, 201 Neuter insects, "the demonstrative case of neuter insects," &c., 249, 298, 314 New countries, Buffon a hater of, 146 Nomenclature, mistaken for knowledge, 141 Nottingham market-place, Erasmus Darwin in, 182, 184, 197 OAK and man, the germs of, indistinguishable, 334 ---- man may become as long-lived as the, 382 Obvious, Erasmus Darwin had no wish to see far beyond the, 197 Oken, alluded to, 72 Old age, the phenomena of, 67, 204, 381 ---- and new worlds, Buffon on the fauna of, 145, &c. One source for all life, Buffon on, 91 ---- Erasmus Darwin on, 109, 233 Oneness of personality between parents and offspring, 37, 38, 39 ---- Buffon on the, 151 ---- Erasmus Darwin and Professor Hering on the, 198-200 ---- Dr. E. Darwin's failure to grasp the whole facts in connection with this, 198, 201, 203 ---- Dr. E. Darwin on, 214, 215 ---- Patrick Matthew on, 322, 323 ---- mentioned, 332, 380, 381 Orang-outang, Buffon on the, 156-159 Organ and use. _See_ "Use." ---- and sense, interaction of the, Buffon on, 127 ---- and faculty, Lamarck on, 255 Organs are living tools, 2 ---- the manufacture of, and that of tools, two species of the same genus, 39, 43, &c. ---- are the expressions of mental phases, 339, 341 Organic structures have a margin, 49, 50 Organic strictures and inorganic, Buffon on the, 153, &c. Organisms, have been developed as man's inventions have, 44, 46, 47, 384 "Origin of Species," the, cannot take permanent rank in the literature of evolution, 62 ---- has no _raison d'être_, if natural selection is not a cause of variation, 346 ---- a piece of intellectual sleight of hand, 346 ---- compared to the advice of a lawyer who wanted to leave plenty of loopholes, or to a cobbled Act of Parliament, 358 ---- is "Hamlet" with the part of Hamlet cut out, 363 ---- most readers would say that it advocated natural selection as the most important cause of variation, 363 ---- and the "Zoonomia," or the "Philosophie Zoologique"; the one upholds natural selection, the other, sense of need, 363 Orthodoxy, scientific, and mystification, Buffon on, 138 ---- scientific, clamouring for endowment, 360 ---- dangers of, 368 Overseeing tends to oversight, 197 PAINS, genius a supreme capacity for taking, 76 Painting, a man should do _something_, no matter what, 51, 52 Paley, quotations from, 12, &c. ---- his argument a juggle, unless some one designed man, much as man designed the watch, 14, 16 ---- on ordinary mechanism, as showing design, 15 ---- on the human neck, 16, 17 ---- on the patella, 18 ---- on the joints, 19, 20 ---- as a writer against evolution, 21 ---- on the ligament that binds the tendons of the instep, 21, 22 ---- opposes the view that structures have been formed through appetency, endeavour or effort, 22, 45 ---- we turn on him and say, Show us your designer, 29 ---- asks, How will our philosopher get an eye? 46 ---- his "Natural Theology" written throughout at the "Zoonomia," 195 ---- never gives a reference when quoting an opponent, 195, 306 Pantheism and Rome will in the end be the two sole combatants, 401 ---- common ground held by Rome and Pantheism, 403-405 ---- of Paul, 404 Parents and offspring, oneness of personality between (_see_ "Personality") Passions, of like passions, men of science are, with other pastors and prophets, 253 Patella, or knee-pan, Paley on the, 18 Paul, St., his pantheistic tendencies, 404 ---- we want to accept him literally, 405 Peace, the, that passeth understanding, 35 Perception and sensation, Buffon on the difference between, 129, 130 Personality, oneness of, between parents and offspring, 37, 38, 39 ---- Buffon on the, 151 ---- Erasmus Darwin and Professor Hering on the, 198-200 ---- Erasmus Darwin's failure to grasp the whole conception, 198, 201, 203 ---- Erasmus Darwin on the, 214, 215 ---- Patrick Matthew on the, 322, 323 ---- mentioned, 332, 380, 381 Personification, the, of Nature, comparatively venial, 367 Pessimism: "Which is the pessimist I or Mr. Darwin?" 59 Peuple des Naturalistes, le, 80, 171 "Philosophie Zoologique," summary of, 261-314 ---- the, leaves "sense of need" on the reader's mind; the "Origin of Species," natural selection, 363 Pig, Buffon on the, 118, &c. Pigeons and fowls, Buffon on, 169 Plaisanterie, Button's disclaimer of, 93 Planted upside down, the vertebrata regarded as vegetables, 137 Plants under domestication, Buffon on, 167, &c. ---- Dr. Erasmus Darwin, on the life of, 206, &c. ---- Lamarck's assertion that they have no action nor habits, 294, 295 Plato upheld teleology, 4 _Plus il a su_, &c., 44 Poem, a, by Dr. Erasmus Darwin, 189 Poetry, Dr. Erasmus Darwin's, 83, 189, 193 Pope's shoes, scientists would step into the, if we would let them, 360, 394 Portrait of Mr. Day, author of "Sandford and Merton," 180 Potto, the missing forefinger of the, 303 Power and desire, interaction of, 44, 45, 47, 127, 217, 221, 300, 323 Praising, with faint damnation, 111 Prescience, need not extend over more than the next step, and yet the whole road may have been travelled presciently, 52, 384 Present, development due to a wise use of the, 50-52 Probable, whatever in the teaching of St. Thomas Aquinas is not probable is to be rejected, 402, 403 Proficiency is due to design if each step was taken designedly, though the end was not far foreseen, 52, 384 Protestantism tends towards disintegration, 396 Proteus principle of life, one, 320 Pump, Erasmus Darwin's poetry about the, 84, 193 Purpose, instinctive actions were once done with a, 54 ---- spent or extinct, and rudimentary organs, 38, 383 Purposive, if each step is purposive, the whole is purposive, 52, 384 Purposiveness: I maintain the lungs to be as purposive us the corkscrew, 5, 6, 7, 58 RACE, the runners in a, and natural selection, 366, 367 ---- significance of the words being used for a breed and a competition, 366, 367 Racehorse or greyhound, "the well-adapted forms of the," 359 Ranunculus aquatilis, Lamarck's passage on, 260, 297 Raleigh, Sir Walter, and evolution, 21, 70 Ray Lankester, Professor, on Hering's theory connecting memory and heredity, 198-200 Reason, there is less reason than feeling in animals, Buffon, 51 ---- perfected becomes instinct, but reasserts itself when the circumstances alter, 54, 55, 56, 203 ---- and instinct, Buffon on, 110, 116 ---- Erasmus Darwin on, 115, 116, 201-205 ---- a less remarkable faculty than generation, Hume on, 233 ---- and instinct, Lamarck on, 256, 274 ---- declared to be incipient instinct, 256 _Réel_, _au_, Buffon's use of these words, 126 Relativity of the sciences, Buffon on the, 140 Religion, Buffon's appeals to, 91, 115 Reopen settled questions, animals cannot, serpents must have no more than four legs, 303 Resume earlier habits, the tendency to, on the approach of a difficulty, 312, 313 Retrogressive, Mr. Darwin's views of evolution retrogressive, 66 Revelation, Buffon's appeals to, against evolution, 91, 115 Reviews of "Evolution, Old and New," 385, &c. Riches, the normal growth of, and evolution, 222 Roman Empire, the, prophetic, 397 Romanes, G. R., on "Evolution, Old and New," 391-393 Rome, Church of, means the same by "gentleman" as we do, 395 ---- I would join, if I could, 395, 396 ---- a unifier, 398 ---- the only source from which a church can come, 398-401 ---- and Pantheism, the ultimate fight will be between, 401 ---- points of agreement between Rome and Pantheists, 403-405 ---- may, and should get rid of Protestantism by outbidding it, 407 Rousseau, Buffon would not play part of, 81 Rudimentary organs, the crux of the early evolutionist in respect of design, 34 ---- are now mere cant formulæ, force of habit, 38, 383 ---- like the protuberance at the bottom of a tobacco-pipe, 38 ---- Buffon would not accept them as designed, 83 ---- Buffon on, 120 ---- Professor Haeckel on, 383 Run, how did the winner come to be able to run ever such a little faster than his fellows, 367 Runners in a race and natural selection, 366, 367 "SANDFORD and Merton," Miss Seward on the author of, 179, 180 Saints will commonly strain a point or two in their own favour, 253 _Saturday Review_ on "Evolution, Old and New," 389-391 Savery, Captain, 54 Science, men of, of like passions with other priests and prophets, 253 ---- not a kingdom into which a poor man can enter easily, 253 ---- the leaders of will generally burke new-born wit unless, &c., 315 ---- not of that kind which desires to know, 392 Scientific orthodoxy and mystification, Buffon on, 138 ---- danger of, 360, 368 Scramble, birds learned to swim through scrambling, 48, 51 Self-indulgence, virtue has ever erred rather on the side of, than on that of asceticism, 35 Sensation, Buffon on, 126, 129 Sense, "in one sense," 355 Sensitive plants, Dr. E. Darwin on, 206, 210 Seriously, Buffon speaking, 126 Serpents, how it is that they have lost their legs, 302 Seward, Miss, her life of Erasmus Darwin, 174, &c. Shakspeare and Handel address the many as well as the few, 81 Shortest day, and shortest day but one, no difference perceptible between, 48 Skeletons, the, of man and of the horse, 88, &c. Skill, the unerring, of natural selection, 9 Siamese twins, desire and power compared to, 218, 300 Simplicity, happy, an example of, 276 Sisters, "his, and his cousins and his aunts," 253 Slit, a slit in one tendon to let another pass through, 20 Something a man should do, no matter what, 51 Sometimes, "equally convenient" ("the survival of the fittest" with natural selection), 9, 354, 365 Son, the people who can get good sons and retain their affection are the only ones worth studying from, 76 Sorbonne, the, and Buffon, 82, 84 Sorbonnes, never do like people who write in this way, 143 Specialists, embryos are, 28 Species, Buffon on the causes or means of transformation, 159, &c. ---- Lamarck on, 267, &c. ---- clusters of, Lamarck on, 288 ---- C. Darwin on, 289 Specific characteristics vary more than generic, Lamarck on, 287, 288 ---- C. Darwin on, 288 Speech, Lamarck on, 313, 314 Spencer, Herbert, on Lamarck's hypothesis, 330, 331 ---- a follower of Buffon, Dr. Erasmus Darwin and Lamarck, 332 Spent, or extinct purpose, and rudimentary organs, 383 Spontaneous: C. Darwin uses this word in connection with variability, 358 ---- variability (or unknown causes), C. Darwin, on what it will account for, or make known, 358 Steam engine, latest development of, not foreseen, though each immediate step in advance was so, 54, 384 ---- design lost sight of in the most common patterns, as with a bird's-nest, or the wheel, 55 Step, if each step is purposive, the whole road has been travelled purposively, 52, 384 ---- only the few nearest are taken definitely, 44, 384 Sterility of hybrids, Lamarck on, 272 ---- C. Darwin on, 273 Stock, Buffon on the, and the diaphragm, 130 Stronger, the, succeed, and the weaker fail, 320, 321 Strongest, the, eat the weaker, 282 Struggle for existence, Buffon on the, 123 ---- and hence modification, according to Dr. Erasmus Darwin, mainly conversant about three wants, 226-229, 232 ---- comparison between Erasmus Darwin and Lamarck's views on the foregoing, 257 ---- Lamarck on the foregoing, 279 ---- and survival of the fittest, Lamarck on the, 281, 282 ---- Patrick Matthew on, 321 Style, Buffon on, 76, 77 Sudden, the question what is too, to be settled by higgling and haggling, 50 ---- modifications, missionaries should avoid trying to effect, 183 Superficial, philosophy of the, 34, 35, 36, 198, 204 Supply and demand, and desire and power, 223, 300 Survival of the fittest, a synonym for natural selection, 9 ---- Dr. Erasmus Darwin on the, 227 ---- in the struggle for existence, Lamarck on the, 281, 282 ---- understood and admitted by Buffon, Erasmus Darwin, and Lamarck, 301 ---- subsequent to modification, and therefore not the cause of it, 302, 346 ---- Patrick Matthew on, 321 ---- this is not a theory, but a fact, 356, 357 Swimming, no shore bird ever set itself to learn, of malice prepense, 48, 51 TAIL, the beaver's, has become an incarnate trowel, 8 Teething, the pain an infant feels is the death-cry of many a good cell, 75 Teleological, failure of the early evolutionists to see their position as, 34 Teleology, statement of the question, 1 ---- Aristotle denied, Plato upheld, 4 ---- the, of Paley and the theologians, 12, &c. ---- internal as much teleology as external, 36 ---- _See_ also "Design." Telescope, Lord Rosse's, and dew-drop, 44, 47 Tempering, the felicitous, of two great contradictory principles, 35 Tendon, a slit in one, to let another pass through, 20 Terminology of botany harder than botany, 108 ---- Buffon on, 140, 141 Test, Buffon's, as to the name an object is to bear, 115 ---- of perception and sensation, Buffon's, 127 Theological writer, few passages in any, displease me more, &c., 368 Theory, the survival of the fittest is a fact, not a theory, 356, 357 Theories, true, Fontenelle on, 22, 23 ---- to be ordered out of court if troublesome, 35 This: "I can no more believe in this," &c., 359 ---- "it is impossible to attribute to this cause," 358 Thomas, St., Aquinas, Papal encyclical on, 402, 403 Thomson, Sir W., natural selection and design, 10 Thought is expressed in organ, 339, 341 Time, Buffon on, 103 ---- Lamarck on, 241 Tobacco-pipe, a rudimentary organ on a, 38 Toes, a man who plays the violin with his, 50 Tools, organs are living tools, 2 ---- the manufacture of, and that of organs, two species of the same genus, 39 Touch, all senses modifications of the sense of touch, 47 Transformation of species, Buffon on the causes or means of, 159 Translation of the "Loves of the Plants" into French, 63, 258, 259 Translation of the "Zoonomia" into German, 71 ---- of Dr. E. Darwin's other works, 195 Trapa Natans, Erasmus Darwin's note on, 260 Treviranus alluded to, 72 Tree, life seen as a tree, by Lamarck, 269 ---- by C. Darwin, 270 ---- nature compared to a, by Buffon, 171 Trees, the blind man who saw men as trees walking, 137 Trowel, the beaver has an incarnate trowel, 8 True, vitally, 227 ---- all very, as far as it goes (that Nature is the most important means of modification), 369 Truism, the survival of the fittest, a, 351 Tutbury bull running, 187 Tyndall, Professor, a rhapsody about C. Darwin, 41 ---- calls evolution C. Darwin's theory, 360, 361 UNCLES and aunts do not beget their nephews and nieces, 367, 376 Unconscious, our acquired habits come to be done as unconsciously as though instinctive, on repetition, 56 ---- difference between my view of the, and Von Hartmann's, 58 Unconsciousness, the, with which habitual actions come to be performed, 37, 38, 39, 56-58, 67, 203, 332, 381 Understanding, the peace of mind that passeth, 35 Unity of the individual, Buffon on the, 127, 128. (_See_ "Oneness") "Unknown causes," according to Mr. Darwin, can do so much, but not so much more, 359 ---- their identity with spontaneous variability, 359 ---- heredity only another name for, unless the "Life and Habit" theory be adopted, 384 Upright position in man and certain apes, and children, Lamarck on, 312 Upside down, the vertebrata are perambulating vegetables planted, 137 Use and organ, 44, 45, 47, 217, 218, 221, 292, 294, 296, 299, 301, 302, 304, 305, 307-309, 311, 323 VACUUM, an omniscient and omnipotent, 28 Vague, efforts and desires are vague in the outset, 47, 52, 384 Variation, C. Darwin declares the fact of variation to be the cause of variation, 8, 9, 347, 369 Variations, one factor of modification provides, the other accumulates, 227 ---- Lamarck strove to discover the law underlying, 337 ---- C. Darwin sees no cause underlying them, 339, 340 ---- according to Lamarck, they will tend to appear in definite directions in large numbers of individuals, for long periods together; according to C. Darwin they will not do thus, 341 ---- must appear before they can be preserved, 346 ---- the cause of variations is the cause of species (Professor Mivart on this), 370 Vary, man cannot vary his practices much more than animals can, 55 "Vestiges of Creation," the, 65 ---- C. Darwin on the, 65 ---- the author of, on Lamarck, 247 ---- Darwin's treatment of, 247, 248 Virtue has ever erred on the side of excess than on that of asceticism, 35 Violin, a man who plays the, with his toes, 50 Vitally true, 227 Volition. (_See_ "Will") Voltaire, Buffon would not play the part of, 81 WALLACE, A. R., his review of Professor Haeckel's "Evolution of Man," 382-384 Want and power, interaction of, 44, 45, 47, 48, 217, 218, 221, 300, 323 Wasp, cutting a fly in half, Dr. Erasmus Darwin on, 205 Watch, Paley's argument from the, 13 Weaker, the strongest eat the, 282 Wealth, the normal growth of, and evolution, 222 Web-footed, how birds, became, 48, 49, 51 ---- development of, birds, Lamarck on, 305 ---- Paley on, 305 Wedge, Buffon let in the thin end of the wedge, by saying that changed habits modify form, 105, 106 Whisky, God keep you from--if he can, 176 Will, Patrick Matthew on, as influencing organism, 320-322. (_See_ also "Desire," "Design," "Want," "Wish") Will-o'-the-wisp, C. Darwin like a, 372 Wish and power, their interaction, 44, 45, 47, 48, 217, 218, 221, 300, 323 Wit, brevity may be its soul, but the leaders of science, &c., 315 Worcester, the Marquis of, 54 Words are apt to turn out compendious false analogies, 365 Worms, reasonable creatures, 255 Worth, nothing worth looking at or doing, except at a fair price, 35 Wright, of Derby, his portrait of Mr. Day, 180 ZEBRA and horse, Buffon on the, 80, 155, 164 "Zoonomia," German translation of the, 71 ---- Paley's "Natural Theology" written at the, 195 ---- fuller quotations from the, 214, &c. ---- the, and the "Origin of Species," the different ideas that an average reader would carry away with him from these two works ("Sense of Need" and "Natural Selection"), 363 _The Mayflower Press, Plymouth, England._ William Brendon & Son, Ltd. 
20556	----	images of public domain material from the Google Print project.) LAMARCK [Illustration: Attempt at a reconstruction of the Profile of Lamarck from an unpublished etching by Dr. Cachet] LAMARCK THE FOUNDER OF EVOLUTION _HIS LIFE AND WORK_ WITH TRANSLATIONS OF HIS WRITINGS ON ORGANIC EVOLUTION By ALPHEUS S. PACKARD, M.D., LL.D. Professor of Zoölogy and Geology in Brown University; author of "Guide to the Study of Insects," "Text-book of Entomology," etc., etc. "La postérité vous honorera!" --_Mlle. Cornelie de Lamarck_ LONGMANS, GREEN, AND CO. 91 AND 93 FIFTH AVENUE, NEW YORK LONDON AND BOMBAY 1901 COPYRIGHT, 1901, BY LONGMANS, GREEN, AND CO. _All rights reserved_ Press of J. J. Little & Co. Astor Place, New York PREFACE Although it is now a century since Lamarck published the germs of his theory, it is perhaps only within the past fifty years that the scientific world and the general public have become familiar with the name of Lamarck and of Lamarckism. The rise and rehabilitation of the Lamarckian theory of organic evolution, so that it has become a rival of Darwinism; the prevalence of these views in the United States, Germany, England, and especially in France, where its author is justly regarded as the real founder of organic evolution, has invested his name with a new interest, and led to a desire to learn some of the details of his life and work, and of his theory as he unfolded it in 1800 and subsequent years, and finally expounded it in 1809. The time seems ripe, therefore, for a more extended sketch of Lamarck and his theory, as well as of his work as a philosophical biologist, than has yet appeared. But the seeker after the details of his life is baffled by the general ignorance about the man--his antecedents, his parentage, the date of his birth, his early training and education, his work as a professor in the Jardin des Plantes, the house he lived in, the place of his burial, and his relations to his scientific contemporaries. Except the _éloges_ of Geoffroy St. Hilaire and Cuvier, and the brief notices of Martins, Duval, Bourguignat, and Bourguin, there is no special biography, however brief, except a _brochure_ of thirty-one pages, reprinted from a few scattered articles by the distinguished anthropologist, M. Gabriel de Mortillet, in the fourth and last volume of a little-known journal, _l'Homme_, entitled _Lamarck. Par un Groupe de Transformistes, ses Disciples_, Paris, 1887. This exceedingly rare pamphlet was written by the late M. Gabriel de Mortillet, with the assistance of Philippe Salmon and Dr. A. Mondière, who with others, under the leadership of Paul Nicole, met in 1884 and formed a _Réunion Lamarck_ and a _Dîner Lamarck_, to maintain and perpetuate the memory of the great French transformist. Owing to their efforts, the exact date of Lamarck's birth, the house in which he lived during his lifetime at Paris, and all that we shall ever know of his place of burial have been established. It is a lasting shame that his remains were not laid in a grave, but were allowed to be put into a trench, with no headstone to mark the site, on one side of a row of graves of others better cared for, from which trench his bones, with those of others unknown and neglected, were exhumed and thrown into the catacombs of Paris. Lamarck left behind him no letters or manuscripts; nothing could be ascertained regarding the dates of his marriages, the names of his wives or of all his children. Of his descendants but one is known to be living, an officer in the army. But his aims in life, his undying love of science, his noble character and generous disposition are constantly revealed in his writings. The name of Lamarck has been familiar to me from my youth up. When a boy, I used to arrange my collection of shells by the Lamarckian system, which had replaced the old Linnean classification. For over thirty years the Lamarckian factors of evolution have seemed to me to afford the foundation on which natural selection rests, to be the primary and efficient causes of organic change, and thus to account for the origin of variations, which Darwin himself assumed as the starting point or basis of his selection theory. It is not lessening the value of Darwin's labors, to recognize the originality of Lamarck's views, the vigor with which he asserted their truth, and the heroic manner in which, against adverse and contemptuous criticism, to his dying day he clung to them. During a residence in Paris in the spring and summer of 1899, I spent my leisure hours in gathering material for this biography. I visited the place of his birth--the little hamlet of Bazentin, near Amiens--and, thanks to the kindness of the schoolmaster of that village, M. Duval, was shown the house where Lamarck was born, the records in the old parish register at the _mairie_ of the birth of the father of Lamarck and of Lamarck himself. The Jesuit Seminary at Amiens was also visited, in order to obtain traces of his student life there, though the search was unsuccessful. My thanks are due to Professor A. Giard of Paris for kind assistance in the loan of rare books, for copies of his own essays, especially his _Leçon d'Ouverture des Cours de l'Évolution des Êtres organisés_, 1888, and in facilitating the work of collecting data. Introduced by him to Professor Hamy, the learned anthropologist and archivist of the Muséum d'Histoire Naturelle, I was given by him the freest access to the archives in the Maison de Buffon, which, among other papers, contained the MS. _Archives du Muséum_; _i.e._, the _Procès verbaux des Séances tenues par les Officiers du Jardin des Plantes_, from 1790 to 1830, bound in vellum, in thirty-four volumes. These were all looked through, though found to contain but little of biographical interest relating to Lamarck, beyond proving that he lived in that ancient edifice from 1793 until his death in 1829. Dr. Hamy's elaborate history of the last years of the Royal Garden and of the foundation of the Muséum d'Histoire Naturelle, in the volume commemorating the centennial of the foundation of the Museum, has been of essential service. My warmest thanks are due to M. Adrien de Mortillet, formerly secretary of the Society of Anthropology of Paris, for most essential aid. He kindly gave me a copy of a very rare pamphlet, entitled _Lamarck. Par un Groupe de Transformistes, ses Disciples_. He also referred me to notices bearing on the genealogy of Lamarck and his family in the _Revue de Gascogne_ for 1876. To him also I am indebted for the privilege of having electrotypes made of the five illustrations in the _Lamarck_, for copies of the composite portrait of Lamarck by Dr. Gachet, and also for a photograph of the _Acte de Naissance_ reproduced by the late M. Salmon. I have also to acknowledge the kindness shown me by Dr. J. Deniker, the librarian of the Bibliothèque du Muséum d'Histoire Naturelle. I had begun in the museum library, which contains nearly if not every one of Lamarck's publications, to prepare a bibliography of all of Lamarck's writings, when, to my surprise and pleasure, I was presented with a very full and elaborate one by the assistant-librarian, M. Godefroy Malloisel. To Professor Edmond Perrier I am indebted for a copy of his valuable _Lamarck et le Transformisme Actuel_, reprinted from the noble volume commemorative of the centennial of the foundation of the Muséum d'Histoire Naturelle, which has proved of much use. Other sources from which biographical details have been taken are Cuvier's _éloge_, and the notice of Lamarck, with a list of many of his writings, in the _Revue biographique de la Société malacologique de France_, 1886. This notice, which is illustrated by three portraits of Lamarck, one of which has been reproduced, I was informed by M. Paul Kleinsieck was prepared by the late J. R. Bourguignat, the eminent malacologist and anthropologist. The notices by Professor Mathias Duval and by L. A. Bourguin have been of essential service. As regards the account of Lamarck's speculative and theoretical views, I have, so far as possible, preferred, by abstracts and translations, to let him tell his own story, rather than to comment at much length myself on points about which the ablest thinkers and students differ so much. It is hoped that Lamarck's writings referring to the evolution theory may, at no distant date, be reprinted in the original, as they are not bulky and could be comprised in a single volume. This life is offered with much diffidence, though the pleasure of collecting the materials and of putting them together has been very great. BROWN UNIVERSITY, PROVIDENCE, R. I., _October, 1901._ CONTENTS CHAPTER PAGE I. BIRTH, FAMILY, YOUTH, AND MILITARY CAREER 1 II. STUDENT LIFE AND BOTANICAL CAREER 15 III. LAMARCK'S SHARE IN THE REORGANIZATION OF THE JARDIN DES PLANTES AND MUSEUM OF NATURAL HISTORY 23 IV. PROFESSOR OF INVERTEBRATE ZOÖLOGY AT THE MUSEUM 32 V. LAST DAYS AND DEATH 51 VI. POSITION IN THE HISTORY OF SCIENCE; OPINIONS OF HIS CONTEMPORARIES AND SOME LATER BIOLOGISTS 64 VII. LAMARCK'S WORK IN METEOROLOGY AND PHYSICAL SCIENCE 79 VIII. LAMARCK'S WORK IN GEOLOGY 89 IX. LAMARCK THE FOUNDER OF INVERTEBRATE PALÆONTOLOGY 124 X. LAMARCK'S OPINIONS ON GENERAL PHYSIOLOGY AND BIOLOGY 156 XI. LAMARCK AS A BOTANIST 173 XII. LAMARCK THE ZOÖLOGIST 180 XIII. THE EVOLUTIONARY VIEWS OF BUFFON AND OF GEOFFROY ST. HILAIRE 198 XIV. THE VIEWS OF ERASMUS DARWIN 216 XV. WHEN DID LAMARCK CHANGE HIS VIEWS REGARDING THE 226 MUTABILITY OF SPECIES? XVI. THE STEPS IN THE DEVELOPMENT OF LAMARCK'S VIEWS ON 232 EVOLUTION BEFORE THE PUBLICATION OF HIS "PHILOSOPHIE ZOOLOGIQUE" XVII. THE "PHILOSOPHIE ZOOLOGIQUE" 279 XVIII. LAMARCK'S THEORY AS TO THE EVOLUTION OF MAN 357 XIX. LAMARCK'S THOUGHTS ON MORALS, AND ON THE RELATION 372 BETWEEN SCIENCE AND RELIGION XX. THE RELATIONS BETWEEN LAMARCKISM AND DARWINISM; 382 NEOLAMARCKISM BIBLIOGRAPHY 425 LIST OF ILLUSTRATIONS ATTEMPT AT A RECONSTRUCTION OF THE PROFILE OF LAMARCK BY DR. GACHET (Photogravure) _Frontispiece_ FACING PAGE BIRTHPLACE OF LAMARCK, FRONT VIEW } } 4 BIRTHPLACE OF LAMARCK " " } ACT OF BIRTH 6 AUTOGRAPH OF LAMARCK, JANUARY 25, 1802 10 LAMARCK AT THE AGE OF 35 YEARS 20 BIRTHPLACE OF LAMARCK. REAR VIEW FROM THE WEST } } 42 MAISON DE BUFFON, IN WHICH LAMARCK LIVED IN PARIS, } 1793-1829 } PORTRAIT OF LAMARCK, WHEN OLD AND BLIND, IN THE COSTUME OF A MEMBER OF THE INSTITUTE. ENGRAVED IN 1824 54 PORTRAIT OF LAMARCK 180 MAISON DE BUFFON, IN WHICH LAMARCK LIVED, 1793-1829 198 É. GEOFFROY ST. HILAIRE 212 LAMARCK, THE FOUNDER OF EVOLUTION. HIS LIFE AND WORK CHAPTER I BIRTH, FAMILY, YOUTH, AND MILITARY CAREER The life of Lamarck is the old, old story of a man of genius who lived far in advance of his age, and who died comparatively unappreciated and neglected. But his original and philosophic views, based as they were on broad conceptions of nature, and touching on the burning questions of our day, have, after the lapse of a hundred years, gained fresh interest and appreciation, and give promise of permanent acceptance. The author of the _Flore Française_ will never be forgotten by his countrymen, who called him the French Linné; and he who wrote the _Animaux sans Vertèbres_ at once took the highest rank as the leading zoölogist of his period. But Lamarck was more than a systematic biologist of the first order. Besides rare experience and judgment in the classification of plants and of animals, he had an unusually active, inquiring, and philosophical mind, with an originality and boldness in speculation, and soundness in reasoning and in dealing with such biological facts as were known in his time, which have caused his views as to the method of organic evolution to again come to the front. As a zoölogical philosopher no one of his time approached Lamarck. The period, however, in which he lived was not ripe for the hearty and general adoption of the theory of descent. As in the organic world we behold here and there prophetic types, anticipating, in their generalized synthetic nature, the incoming, ages after, of more specialized types, so Lamarck anticipated by more than half a century the principles underlying the present evolutionary theories. So numerous are now the adherents, in some form, of Lamarck's views, that at the present time evolutionists are divided into Darwinians and Lamarckians or Neolamarckians. The factors of organic evolution as stated by Lamarck, it is now claimed by many, really comprise the primary or foundation principles or initiative causes of the origin of life-forms. Hence not only do many of the leading biologists of his native country, but some of those of Germany, of the United States, and of England, justly regard him as the founder of the theory of organic evolution. Besides this, Lamarck lived in a transition period. He prepared the way for the scientific renascence in France. Moreover, his simple, unselfish character was a rare one. He led a retired life. His youth was tinged with romance, and during the last decade of his life he was blind. He manfully and patiently bore adverse criticisms, ridicule, forgetfulness, and inappreciation, while, so far from renouncing his theoretical views, he tenaciously clung to them to his dying day. The biography of such a character is replete with interest, and the memory of his unselfish and fruitful devotion to science should be forever cherished. His life was also notable for the fact that after his fiftieth year he took up and mastered a new science; and at a period when many students of literature and science cease to be productive and rest from their labors, he accomplished the best work of his life--work which has given him lasting fame as a systematist and as a philosophic biologist. Moreover, Lamarckism comprises the fundamental principles of evolution, and will always have to be taken into consideration in accounting for the origin, not only of species, but especially of the higher groups, such as orders, classes, and phyla. This striking personage in the history of biological science, who has made such an ineffaceable impression on the philosophy of biology, certainly demands more than a brief _éloge_ to keep alive his memory. ~ ~ ~ ~ ~ Jean-Baptiste-Pierre-Antoine de Monet, Chevalier de Lamarck, was born August 1, 1744, at Bazentin-le-Petit. This little village is situated in Picardy, or what is now the Department of the Somme, in the Arrondissement de Péronne, Canton d'Albert, a little more than four miles from Albert, between this town and Bapaume, and near Longueval, the nearest post-office to Bazentin. The village of Bazentin-le-Grand, composed of a few more houses than its sister hamlet, is seen half a mile to the southeast, shaded by the little forest such as borders nearly every town and village in this region. The two hamlets are pleasantly situated in a richly cultivated country, on the chalk uplands or downs of Picardy, amid broad acres of wheat and barley variegated with poppies and the purple cornflower, and with roadsides shaded by tall poplars. The peasants to the number of 251 compose the diminishing population. There were 356 in 1880, or about that date. The silence of the single little street, with its one-storied, thatched or tiled cottages, is at infrequent intervals broken by an elderly dame in her _sabots_, or by a creaking, rickety village cart driven by a farmer-boy in blouse and hob-nailed shoes. The largest inhabited building is the _mairie_, a modern structure, at one end of which is the village school, where fifteen or twenty urchins enjoy the instructions of the worthy teacher. A stone church, built in 1774, and somewhat larger than the needs of the hamlet at present require, raises its tower over the quiet scene. Our pilgrimage to Bazentin had for its object the discovery of the birthplace of Lamarck, of which we could obtain no information in Paris. Our guide from Albert took us to the _mairie_, and it was with no little satisfaction that we learned from the excellent village teacher, M. Duval, that the house in which the great naturalist was born was still standing, and but a few steps away, in the rear of the church and of the _mairie_. With much kindness he left his duties in the schoolroom, and accompanied us to the ancient structure. [Illustration: BIRTHPLACE OF LAMARCK, FRONT VIEW] [Illustration: BIRTHPLACE OF LAMARCK] The modest _château_ stands a few rods to the westward of the little village, and was evidently the seat of the leading family of the place. It faces east and is a two-storied house of the shape seen everywhere in France, with its high, incurved roof; the walls, nearly a foot and a half thick, built of brick; the corners and windows of blocks of white limestone. It is about fifty feet long and twenty-five feet wide. Above the roof formerly rose a small tower. There is no porch over the front door. Within, a rather narrow hall passes through the centre, and opens into a large room on each side. What was evidently the drawing-room or _salon_ was a spacious apartment with a low white wainscot and a heavy cornice. Over the large, roomy fireplace is a painting on the wood panel, representing a rural scene, in which a shepherdess and her lover are engaged in other occupations than the care of the flock of sheep visible in the distance. Over the doorway is a smaller but quaint painting of the same description. The house is uninhabited, and perhaps uninhabitable--indeed almost a ruin--and is used as a storeroom for wood and rubbish by the peasants in the adjoining house to the left, on the south. The ground in front was cultivated with vegetables, not laid down to a lawn, and the land stretched back for perhaps three hundred to four hundred feet between the old garden walls. Here, amid these rural scenes, even now so beautiful and tranquil, the subject of our sketch was born and lived through his infancy and early boyhood.[1] If his parents did not possess an ample fortune, they were blessed with a numerous progeny, for Lamarck was the eleventh and youngest child, and seems to have survived all the others. Biographers have differed as to the date of the birth of Lamarck.[2] Happily the exact date had been ascertained through the researches of M. Philippe Salmon; and M. Duval kindly showed us in the thin volume of records, with its tattered and torn leaves, the register of the _Acte de Naissance_, and made a copy of it, as follows: _Extrait du Registre aux Actes de Baptême de la Commune de Bazentin, pour l'Année 1744._ L'an mil sept cent quarante-quatre, le premier août est né en légitime mariage et le lendemain a été baptisé par moy curé soussigné Jean Baptiste Pierre Antoine, fils de Messire Jacques Philippe de Monet, chevalier de Lamarck, seigneur des Bazentin grand et petit et de haute et puissante Dame Marie Françoise de Fontaine demeurant en leur château de Bazentin le petit, son parrain a été Messire Jean Baptiste de Fossé, prêtre-chanoine de l'église collégiale de St. Farcy de Péronne, y demeurant, sa marraine Dame Antoinette Françoise de Bucy, nièce de Messire Louis Joseph Michelet, chevalier, ancien commissaire de l'artillerie de France demeurante au château de Guillemont, qui ont signé avec mon dit sieur de Bazentin et nous. Ont signé: De Fossé, De Bucy Michelet, Bazentin. Cozette, curé. [Illustration: ACT OF BIRTH] Of Lamarck's parentage and ancestry there are fortunately some traces. In the _Registre aux Actes de Baptême pour l'Année 1702_, still preserved in the _mairie_ of Bazentin-le-Petit, the record shows that his father was born in February, 1702, at Bazentin. The infant was baptised February 16, 1702, the permission to the _curé_ by Henry, Bishop of Amiens, having been signed February 3, 1702. Lamarck's grandparents were, according to this certificate of baptism, Messire Philippe de Monet de Lamarck, Ecuyer, Seigneur des Bazentin, and Dame Magdeleine de Lyonne. The family of Lamarck, as stated by H. Masson,[3] notwithstanding his northern and almost Germanic name of Chevalier de Lamarck, originated in the southwest of France. Though born at Bazentin, in old Picardy, it is not less true that he descended on the paternal side from an ancient house of Béarn, whose patrimony was very modest. This house was that of Monet. Another genealogist, Baron C. de Cauna,[4] tells us that there is no doubt that the family of Monet in Bigorre[5] was divided. One of its representatives formed a branch in Picardy in the reign of Louis XIV. or later. Lamarck's grandfather, Philippe de Monet, "seigneur de Bazentin et autres lieux," was also "chevalier de l'ordre royal et militaire de Saint-Louis, commandant pour le roi en la ville et château de Dinan, pensionnaire de sa majesté." The descendants of Philippe de Lamarck were, adds de Cauna, thus thrown into two branches, or at least two offshoots or stems (_brisures_), near Péronne. But the actual posterity of the Monet of Picardy was reduced to a single family, claiming back, with good reason, to a southern origin. One of its scions in the maternal line was a brilliant officer of the military marine and also son-in-law of a very distinguished naval officer. The family of Monet was represented among the French nobility of 1789 by Messires de Monet de Caixon and de Monet de Saint-Martin. By marriage their grandson was connected with an honorable family of Montant, near Saint-Sever-Cap. Another authority, the Abbé J. Dulac, has thrown additional light on the genealogy of the de Lamarck family, which, it may be seen, was for at least three centuries a military one.[6] The family of Monet, Seigneur de Saint-Martin et de Sombran, was maintained as a noble one by order of the Royal Council of State of June 20, 1678. He descended (I) from Bernard de Monet, esquire, captain of the château of Lourdes, who had as a son (II) Étienne de Monet, esquire, who, by contract dated August 15, 1543, married Marguerite de Sacaze. He was the father of (III) Pierre de Monet, esquire, "Seigneur d'Ast, en Béarn, guidon des gendarmes de la compagnie du roi de Navarre." From him descended (IV) Étienne de Monet, esquire, second of the name, "Seigneur d'Ast et Lamarque, de Julos." He was a captain by rank, and bought the estate of Saint-Martin in 1592. He married, in 1612, Jeanne de Lamarque, daughter of William de Lamarck, "Seigneur de Lamarque et de Bretaigne." They had three children, the third of whom was Philippe, "chevalier de Saint-Louis, commandant du château de Dinan, Seigneur de Bazentin, en Picardy," who, as we have already seen, was the father of the naturalist Lamarck, who lived from 1744 to 1829. The abbé relates that Philippe, the father of the naturalist, was born at Saint-Martin, in the midst of Bigorre, "_in pleine Bigorre_," and he very neatly adds that "the Bigorrais have the right to claim for their land of flowers one of the glories of botany."[7] The name was at first variously spelled de Lamarque, de la Marck, or de Lamarck. He himself signed his name, when acting as secretary of the Assembly of Professors-administrative of the Museum of Natural History during the years of the First Republic, as plain Lamarck. The inquiry arises how, being the eleventh child, he acquired the title of chevalier, which would naturally have become extinct with the death of the oldest son. The Abbé Dulac suggests that the ten older of the children had died, or that by some family arrangement he was allowed to add the domanial name to the patronymic one. Certainly he never tarnished the family name, which, had it not been for him, would have remained in obscurity. As to his father's tastes and disposition, what influence his mother had in shaping his character, his home environment, as the youngest of eleven children, the nature of his education in infancy and boyhood, there are no sources of information. But several of his brothers entered the army, and the domestic atmosphere was apparently a military one. Philippe de Lamarck, with his large family, had endowed his first-born son so that he could maintain the family name and title, and had found situations for several of the others in the army. Jean Lamarck did not manifest any taste for the clerical profession. He lived in a martial atmosphere. For centuries his ancestors had borne arms. His eldest brother had been killed in the breach at the siege of Berg-op-Zoom; two others were still in the service, and in the troublous times at the beginning of the war in 1756, a young man of high spirit and courage would naturally not like to relinquish the prospect of renown and promotion. But, yielding to the wishes of his father, he entered as a student at the college of the Jesuits at Amiens.[8] His father dying in 1760, nothing could induce the incipient abbé, then seventeen years of age, to longer wear his bands. Immediately on returning home he bought himself a wretched horse, for want of means to buy a better one, and, accompanied by a poor lad of his village, he rode across the country to join the French army, then campaigning in Germany. [Illustration: AUTOGRAPH OF LAMARCK, JANUARY 25, 1802 je prie le Citoyen qui assemble dans le Magazin de l'imprimerie du Citoyen Agasse de remettre à Madame chevalier Cent exemplaires de mon hydrogeologie, pour les Brocher. Paris le 5 pluviose an dix Lamarck] He carried with him a letter of recommendation from one of his neighbors on an adjoining estate in the country, Madame de Lameth, to M. de Lastic, colonel of the regiment of Beaujolais.[9] "We can imagine [says Cuvier] the feelings of this officer on thus finding himself hampered with a boy whose puny appearance made him seem still younger than he was. However, he sent him to his quarters, and then busied himself with his duties. The period indeed was a critical one. It was the 16th of July, 1761. The Marshal de Broglie had just united his army with that of the Prince de Soubise, and the next day was to attack the allied army commanded by the Prince Ferdinand of Brunswick. At the break of day M. de Lastic rode along the front of his corps, and the first man that met his gaze was the new recruit, who, without saying anything to him, had placed himself in the front rank of a company of grenadiers, and nothing could induce him to quit his post. "It is a matter of history that this battle, which bears the name of the little village of Fissingshausen, between Ham and Lippstadt, in Westphalia, was lost by the French, and that the two generals, mutually accusing each other of this defeat, immediately separated, and abandoned the campaign. "During the movement of the battle, de Lamarck's company was stationed in a position exposed to the direct fire of the enemy's artillery. In the confusion of the retreat he was forgotten. Already all the officers and non-commissioned officers had been killed; there remained only fourteen men, when the oldest grenadier, seeing that there were no more of the French troops in sight, proposed to the young volunteer, become so promptly commander, to withdraw his little troop. 'But we are assigned to this post,' said the boy, 'and we should not withdraw from it until we are relieved.' And he made them remain there until the colonel, seeing that the squad did not rally, sent him an orderly, who crept by all sorts of covered ways to reach him. This bold stand having been reported to the marshal, he promoted him on the field to the rank of an officer, although his order had prescribed that he should be very chary of these kinds of promotions." His physical courage shown at this age was paralleled by his moral courage in later years. The staying power he showed in immovably adhering to his views on evolution through many years, and under the direct and raking fire of harsh and unrelenting criticism and ridicule from friend and foe, affords a striking contrast to the moral timidity shown by Buffon when questioned by the Sorbonne. We can see that Lamarck was the stuff martyrs are made of, and that had he been tried for heresy he would have been another Tycho Brahe. Soon after, de Lamarck was nominated to a lieutenancy; but so glorious a beginning of his military career was most unexpectedly checked. A sudden accident forced him to leave the service and entirely change his course of life. His regiment had been, during peace, sent into garrison, first at Toulon and then at Monaco. While there a comrade in play lifted him by the head; this gave rise to an inflammation of the lymphatic glands of the neck, which, not receiving the necessary attention on the spot, obliged him to go to Paris for better treatment. "The united efforts [says Cuvier] of several surgeons met with no better success, and danger had become very imminent, when our _confrère_, the late M. Tenon, with his usual sagacity, recognized the trouble, and put an end to it by a complicated operation, of which M. de Lamarck preserved deep scars. This treatment lasted for a year, and, during this time, the extreme scantiness of his resources confined him to a solitary life, when he had the leisure to devote himself to meditations." FOOTNOTES: [1] In the little chapel next the church lies buried, we were told by M. Duval, a Protestant of the family of de Guillebon, the purchaser (_acquéreur_) of the _château_. Whether the estate is now in the hands of his heirs we did not ascertain. [2] As stated by G. de Mortillet, the date of his birth is variously given. Michaud's _Dictionnaire Biographique_ gives the date April 1; other authors, April 11; others, the correct one, August 1, 1744. (_Lamarck. Par un Groupe de Transformistes, ses Disciples._ _L'Homme_, iv. p. 289, 1887.) [3] "Sur la maison de Viella--les Mortiers-brévise et les Montalembert en Gascogne--et sur le naturaliste Lamarck." Par Hippolyte Masson. (_Revue de Gascogne_, xvii., pp. 141-143, 1876.) [4] _Ibid._, p. 194. [5] A small town in southwestern France, near Lourdes and Pau; it is about eight miles north of Tarbes, in Gascony. [6] _Revue de Gascogne_, pp. 264-269, 1876. [7] The abbé attempts to answer the question as to what place gave origin to the name of Lamarck, and says: "The author of the history of Béarn considered the cradle of the race to have been the freehold of Marca, parish of Gou (Basses-Pyrénées). A branch of the family established in le Magnoac changed its name of Marca to that of La Marque." It was M. d'Ossat who gave rise to this change by addressing his letters to M. de Marca (at the time when he was preceptor of his nephew), sometimes under the name of M. Marca, sometimes _M. la Marqua_, or of _M. de la Marca_, but more often still under that of _M. de la Marque_, "with the object, no doubt, of making him a Frenchman" ("_dans la vue sans doute de le franciser_"). (_Vie du Cardinal d'Ossat_, tome i., p. 319.) "To recall their origin, the branch of Magnoac to-day write their name _Marque-Marca_. If the Marca of the historian belongs to Béarn, the Lamarque of the naturalist, an orthographic name in principle, proceeds from Bigorre, actually chosen (_désignée_) by _Lamarcq, Pontacq, or Lamarque près Béarn_. That the _Lamarque_ of the botanist of the royal cabinet distinguished himself from all the _Lamarques_ of Béarn or of Bigorre, which it bears (_qu'il gise_) to this day in the Hautes-Pyrénées, Canton d'Ossun, we have many proofs: Aast at some distance, Bourcat and Couet all near l'Abbaye Laïque, etc. The village so determined is called in turn _Marca_, _La Marque_, _Lamarque_; names predestined to several destinations; judge then to the mercy of a botanist, _Lamarck_, _La Marck_, _Delamarque_, _De Lamarck_, who shall determine their number? As to the last, I only explain it by a fantasy of the man who would de-Bigorrize himself in order to Germanize himself in the hope, apparently, that at the first utterance of the name people would believe that he was from the _outre Rhin_ rather than from the borders of Gave or of Adour. Consequently a hundred times more learned and a hundred times more worthy of a professorship in the Museum, where Monet would seem (_entrevait_) much less than Lamarque." It may be added that Béarn was an ancient province of southern France nearly corresponding to the present Department of Basses-Pyrénées. Its capital was Pau. [8] We have been unable to ascertain the date when young Lamarck entered the seminary. On making inquiries in June, 1899, at the Jesuits' Seminary in Amiens, one of the faculty, after consultation with the Father Superior, kindly gave us in writing the following information as to the exact date: "The registers of the great seminary were carried away during the French Revolution, and we do not know whither they have been transported, and whether they still exist to-day. Besides, it is very doubtful whether Lamarck resided here, because only ecclesiastics preparing for receiving orders were received in the seminary. Do you not confound the seminary with the ancient college of Rue Poste de Paris, college now destroyed?" [9] We are following the _Éloge_ of Cuvier almost verbatim, also reproduced in the biographical notice in the _Revue biographique de la Société Malacologique de France_, said to have been prepared by J. R. Bourguignat. CHAPTER II STUDENT LIFE AND BOTANICAL CAREER The profession of arms had not led Lamarck to forget the principles of physical science which he had received at college. During his sojourn at Monaco the singular vegetation of that rocky country had attracted his attention, and Chomel's _Traité des Plantes usuelles_ accidentally falling into his hands had given him some smattering of botany. Lodged at Paris, as he has himself said, in a room much higher up than he could have wished, the clouds, almost the only objects to be seen from his windows, interested him by their ever-changing shapes, and inspired in him his first ideas of meteorology. There were not wanting other objects to excite interest in a mind which had always been remarkably active and original. He then realized, to quote from his biographer, Cuvier, what Voltaire said of Condorcet, that solid enduring discoveries can shed a lustre quite different from that of a commander of a company of infantry. He resolved to study some profession. This last resolution was but little less courageous than the first. Reduced to a pension (_pension alimentaire_) of only 400 francs a year, he attempted to study medicine, and while waiting until he had the time to give to the necessary studies, he worked in the dreary office of a bank. The meditations, the thoughts and aspirations of a contemplative nature like his, in his hours of work or leisure, in some degree consoled the budding philosopher during this period of uncongenial labor, and when he did have an opportunity of communicating his ideas to his friends, of discussing them, of defending them against objection, the hardships of his workaday life were for the time forgotten. In his ardor for science all the uncongenial experiences of his life as a bank clerk vanished. Like many another rising genius in art, literature, or science, his zeal for knowledge and investigation in those days of grinding poverty fed the fires of his genius, and this was the light which throughout his long poverty-stricken life shed a golden lustre on his toilsome existence. He did not then know that the great Linné, the father of the science he was to illuminate and so greatly to expand, also began life in extreme poverty, and eked out his scanty livelihood by mending over again for his own use the cast-off shoes of his fellow-students. (Cuvier.) Bourguin[10] tells us that Lamarck's medical course lasted four years, and this period of severe study--for he must have made it such--evidently laid the best possible foundation that Paris could then afford for his after studies. He seems, however, to have wavered in his intentions of making medicine his life work, for he possessed a decided taste for music. His eldest brother, the Chevalier de Bazentin, strongly opposed, and induced him to abandon this project, though not without difficulty. At about this time the two brothers lived in a quiet village[11] near Paris, and there for a year they studied together science and history. And now happened an event which proved to be the turning point, or rather gave a new and lasting impetus to Lamarck's career and decided his vocation in life. In one of their walks they met the philosopher and sentimentalist, Jean Jacques Rousseau. We know little about Lamarck's acquaintance with this genius, for all the details of his life, both in his early and later years, are pitifully scanty. Lamarck, however, had attended at the Jardin du Roi a botanical course, and now, having by good fortune met Rousseau, he probably improved the acquaintance, and, found by Rousseau to be a congenial spirit, he was soon invited to accompany him in his herborizations. Still more recently Professor Giard[12] has unearthed from the works of Rousseau the following statement by him regarding species: "Est-ce qu'à proprement parler il n'existerait point d'espèces dans la nature, mais seulement des individus?"[13] In his _Discours sur l'Inégalité parmi les Hommes_ is the following passage, which shows, as Giard says, that Rousseau perfectly understood the influence of the _milieu_ and of wants on the organism; and this brilliant writer seems to have been the first to suggest natural selection, though only in the case of man, when he says that the weaker in Sparta were eliminated in order that the superior and stronger of the race might survive and be maintained. "Accustomed from infancy to the severity of the weather and the rigors of the seasons, trained to undergo fatigue, and obliged to defend naked and without arms their life and their prey against ferocious beasts, or to escape them by flight, the men acquired an almost invariably robust temperament; the infants, bringing into the world the strong constitution of their fathers, and strengthening themselves by the same kind of exercise as produced it, have thus acquired all the vigor of which the human species is capable. Nature uses them precisely as did the law of Sparta the children of her citizens. She rendered strong and robust those with a good constitution, and destroyed all the others. Our societies differ in this respect, where the state, in rendering the children burdensome to the father, indirectly kills them before birth."[14] Soon Lamarck abandoned not only a military career, but also music, medicine, and the bank, and devoted himself exclusively to science. He was now twenty-four years old, and, becoming a student of botany under Bernard de Jussieu, for ten years gave unremitting attention to this science, and especially to a study of the French flora. Cuvier states that the _Flore Française_ appeared after "six months of unremitting labor." However this may be, the results of over nine preceding years of study, gathered together, written, and printed within the brief period of half a year, was no hasty _tour de force_, but a well-matured, solid work which for many years remained a standard one. It brought him immediate fame. It appeared at a fortunate epoch. The example of Rousseau and the general enthusiasm he inspired had made the study of flowers very popular--"_une science à la mode_," as Cuvier says--even among many ladies and in the world of fashion, so that the new work of Lamarck, though published in three octavo volumes, had a rapid success. The preface was written by Daubenton.[15] Buffon also took much interest in the work, opposing as it did the artificial system of Linné, for whom he had, for other reasons, no great degree of affection. He obtained the privilege of having the work published at the royal printing office at the expense of the government, and the total proceeds of the sale of the volumes were given to the author. This elaborate work at once placed young Lamarck in the front rank of botanists, and now the first and greatest honor of his life came to him. The young lieutenant, disappointed in a military advancement, won his spurs in the field of science. A place in botany had become vacant at the Academy of Sciences, and M. de Lamarck having been presented in the second rank (_en seconde ligne_), the ministry, a thing almost unexampled, caused him to be given by the king, in 1779, the preference over M. Descemet, whose name was presented before his, in the first rank, and who since then, and during a long life, never could recover the place which he unjustly lost.[16] "In a word, the poor officer, so neglected since the peace, obtained at one stroke the good fortune, always very rare, and especially so at that time, of being both the recipient of the favor of the Court and of the public."[17] [Illustration: LAMARCK AT THE AGE OF 35 YEARS] The interest and affection felt for him by Buffon were of advantage to him in another way. Desiring to have his son, whom he had planned to be his successor as Intendant of the Royal Garden, and who had just finished his studies, enjoy the advantage of travel in foreign lands, Buffon proposed to Lamarck to go with him as a guide and friend; and, not wishing him to appear as a mere teacher, he procured for him, in 1781, a commission as Royal Botanist, charged with visiting the foreign botanical gardens and museums, and of placing them in communication with those of Paris. His travels extended through portions of the years 1781 and 1782. According to his own statement,[18] in pursuit of this object he collected not only rare and interesting plants which were wanting in the Royal Garden, but also minerals and other objects of natural history new to the Museum. He went to Holland, Germany, Hungary, etc., visiting universities, botanical gardens, and museums of natural history. He examined the mines of the Hartz in Hanover, of Freyburg in Saxony, of Chemnitz and of Cremnitz in Hungary, making there numerous observations which he incorporated in his work on physics, and sent collections of ores, minerals, and seeds to Paris. He also made the acquaintance of the botanists Gleditsch at Berlin, Jacquin at Vienna, and Murray at Göttingen. He obtained some idea of the magnificent establishments in these countries devoted to botany, "and which," he says, "ours do not yet approach, in spite of all that had been done for them during the last thirty years."[19] On his return, as he writes, he devoted all his energies and time to research and to carrying out his great enterprises in botany; as he stated: "Indeed, for the last ten years my works have obliged me to keep in constant activity a great number of artists, such as draughtsmen, engravers, and printers."[20] But the favor of Buffon, powerful as his influence was,[21] together with the aid of the minister, did not avail to give Lamarck a permanent salaried position. Soon after his return from his travels, however, M. d'Angiviller, the successor of Buffon as Intendant of the Royal Garden, who was related to Lamarck's family, created for him the position of keeper of the herbarium of the Royal Garden, with the paltry salary of 1,000 francs. According to the same _État_, Lamarck had now been attached to the Royal Garden five years. In 1789 he received as salary only 1,000 livres or francs; in 1792 it was raised to the sum of 1,800 livres. FOOTNOTES: [10] _Les Grand Naturalists Français au Commencement du XIX Siècle._ [11] Was this quiet place in the region just out of Paris possibly near Mont Valérien? He must have been about twenty-two years old when he met Rousseau and began to study botany seriously. His _Flore Française_ appeared in 1778, when he was thirty-four years old. Rousseau, at the end of his checkered life, from 1770 to 1778, lived in Paris. He often botanized in the suburbs; and Mr. Morley, in his _Rousseau_, says that "one of his greatest delights was to watch Mont Valérien in the sunset" (p. 436). Rousseau died in Paris in 1778. That Rousseau expressed himself vaguely in favor of evolution is stated by Isidore Geoffroy St. Hilaire, who quotes a "_Phrase, malheureusement un peu ambiguë, qui semble montrer, dans se grand écrivain, un partisan de plus de la variabilité du type_." (_Résumé des Vues sur l'espèce organique_, p. 18, Paris, 1889.) The passage is quoted in Geoffroy's _Histoire Naturelle Générale des Règnes organiques_, ii., ch. I., p. 271. I have been unable to verify this quotation. [12] _Leçon d'Ouverture du Cours de l'Évolution des Êtres organisés._ Paris, 1888. [13] _Dictionnaire des Termes de la Botanique._ Art. APHRODITE. [14] _Discours sur l'Origine et les Fondements de l'Inégalité parmi les Hommes._ 1754. [15] Since 1742, the keeper and demonstrator of the Cabinet, who shared with Thouin, the chief gardener, the care of the Royal Gardens. Daubenton was at that time the leading anatomist of France, and after Buffon's death he gathered around him all the scientific men who demanded the transformation of the superannuated and incomplete Jardin du Roi, and perhaps initiated the movement which resulted five years later in the creation of the present Museum of Natural History. (Hamy, _l. c._, p. 12.) [16] De Mortillet (_Lamarck. Par un Groupe de Transformistes_, p. 11) states that Lamarck was elected to the Academy at the age of thirty; but as he was born in 1744, and the election took place in 1779, he must have been thirty-five years of age. [17] Cuvier's _Éloge_, p. viii.; also _Revue biographique de la Société Malacologique_, p. 67. [18] See letters to the Committee of Public Instruction. [19] Cuvier's _Éloge_, p. viii; also Bourguignat in _Revue biog. Soc. Malacologique_, p. 67. [20] He received no remuneration for this service. As was afterwards stated in the National Archives, _État des personnes attachées au Muséum National d'Histoire Naturelle a l'époque du messidor an II de la République_, he "sent to this establishment seeds of rare plants, interesting minerals, and observations made during his travels in Holland, Germany, and in France. He did not receive any compensation for this service." [21] "The illustrious Intendant of the Royal Garden and Cabinet had concentrated in his hands the most varied and extensive powers. Not only did he hold, like his predecessors, the _personnel_ of the establishment entirely at his discretion, but he used the appropriations which were voted to him with a very great independence. Thanks to the universal renown which he had acquired both in science and in literature, Buffon maintained with the men who succeeded one another in office relations which enabled him to do almost anything he liked at the Royal Garden." His manner to public men, as Condorcet said, was conciliatory and tactful, and to his subordinates he was modest and unpretending. (Professor G. T. Hamy, _Les Derniers Jours du Jardin du Roi_, etc., p. 3.) Buffon, after nearly fifty years of service as Intendant, died April 16, 1788. CHAPTER III LAMARCK'S SHARE IN THE REORGANIZATION OF THE JARDIN DES PLANTES AND MUSEUM OF NATURAL HISTORY Even in his humble position as keeper of the herbarium, with its pitiable compensation, Lamarck, now an eminent botanist, with a European reputation, was by no means appreciated or secure in his position. He was subjected to many worries, and, already married and with several children, suffered from a grinding poverty. His friend and supporter, La Billarderie, was a courtier, with much influence at the Tuileries, but as Intendant of the Royal Garden without the least claim to scientific fitness for the position; and in 1790 he was on the point of discharging Lamarck.[22] On the 20th of August the Finance Committee reduced the expenses of the Royal Garden and Cabinet, and, while raising the salary of the professor of botany, to make good the deficiency thus ensuing suppressed the position of keeper of the herbarium, filled by Lamarck. Lamarck, on learning of this, acted promptly, and though in this cavalier way stricken off from the rolls of the Royal Garden, he at once prepared, printed, and distributed among the members of the National Assembly an energetic claim for restoration to his office.[23] His defence formed two brochures; in one he gave an account of his life, travels, and works, and in the other he showed that the place which he filled was a pressing necessity, and could not be conveniently or usefully added to that of the professor of botany, who was already overworked. This manly and able plea in his own defence also comprised a broad, comprehensive plan for the organization and development of a great national museum, combining both vast collections and adequate means of public instruction. The paper briefly stated, in courteous language, what he wished to say to public men, in general animated with good intentions, but little versed in the study of the sciences and the knowledge of their application. It praised, in fit terms, the work of the National Assembly, and gave, without too much emphasis, the assurance of an entire devotion to the public business. Then in a very clear and comprehensive way were given all the kinds of service which an establishment like the Royal Garden should render to the sciences and arts, and especially to agriculture, medicine, commerce, etc. Museums, galleries, and botanical gardens; public lectures and demonstrations in the museum and school of botany; an office for giving information, the distribution of seeds, etc.--all the resources already so varied, as well as the facilities for work at the Jardin, passed successively in review before the representatives of the country, and the address ended in a modest request to the Assembly that its author be allowed a few days to offer some observations regarding the future organization of this great institution. The Assembly, adopting the wise views announced in the manifest which had been presented by the officers of the Jardin and Cabinet, sent the address to the Committee, and gave a month's time to the petitioners to prepare and present a plan and regulations which should establish the organization of their establishment.[24] It was in 1790 that the decisive step was taken by the officers of the Royal Garden[25] and Cabinet of Natural History which led to the organization of the present Museum of Natural History as it is to-day. Throughout the proceedings, Lamarck, as at the outset, took a prominent part, his address having led the Assembly to invite the officers of the double establishment to draw up rules for its government. The officers met together August 23d, and their distrust and hostility against the Intendant were shown by their nomination of Daubenton, the Nestor of the French savants, to the presidency, although La Billarderie, as representing the royal authority, was present at the meeting. At the second meeting (August 24th) he took no part in the proceedings, and absented himself from the third, held on August 27, 1790. It will be seen that even while the office of Intendant lasted, that official took no active part in the meetings or in the work of the institution, and from that day to this it has been solely under the management of a director and scientific corps of professors, all of them original investigators as well as teachers. Certainly the most practical and efficient sort of organization for such an establishment.[26] Lamarck, though holding a place subordinate to the other officers, was present, as the records of the proceedings of the officers of the Jardin des Plantes at this meeting show. During the middle of 1791, the Intendant, La Billarderie, after "four years of incapacity," placed his resignation in the hands of the king. The Minister of the Interior, instead of nominating Daubenton as Intendant, reserved the place for a _protégé_, and, July 1, 1791, sent in the name of Jacques-Henri Bernardin de Saint-Pierre, the distinguished author of _Paul et Virginie_ and of _Études sur la Nature_. The new Intendant was literary in his tastes, fond of nature, but not a practical naturalist. M. Hamy wittily states that "Bernardin Saint-Pierre contemplated and dreamed, and in his solitary meditations had imagined a system of the world which had nothing in common with that which was to be seen in the Faubourg Saint Victor, and one can readily imagine the welcome that the officers of the Jardin gave to the singular naturalist the Tuileries had sent them."[27] Lamarck suffered an indignity from the intermeddling of this second Intendant of the Jardin. In his budget of expenses[28] sent to the Minister of the Interior, Bernardin de Saint-Pierre took occasion to refer to Lamarck in a disingenuous and blundering way, which may have both amused and disgusted him. But the last days of the Jardin du Roi were drawing to a close, and a new era in French natural science, signalized by the reorganization of the Jardin and Cabinet under the name of the _Muséum d'Histoire Naturelle_, was dawning. On the 6th of February, 1793, the National Convention, at the request of Lakanal,[29] ordered the Committees of Public Instruction and of Finances to at once make a report on the new organization of the administration of the Jardin des Plantes. Lakanal consulted with Daubenton, and inquired into the condition and needs of the establishment; Daubenton placed in his hands the brochure of 1790, written by Lamarck. The next day Lakanal, after a short conference with his colleagues of the Committee of Public Instruction, read in the tribune a short report and a decree which the Committee adopted without discussion. Their minds were elsewhere, for grave news had come in from all quarters. The Austrians were bombarding Valenciennes, the Prussians had invested Mayence, the Spanish were menacing Perpignan, and bands of Vendeans had seized Saumur after a bloody battle; while at Caen, at Evreux, at Bordeaux, at Marseilles, and elsewhere, muttered the thunders of the outbreaks provoked by the proscription of the Girondins. So that under these alarming conditions the decree of the 10th of June, in spite of its importance to science and higher learning in France, was passed without discussion. In his _Lamarck_ De Mortillet states explicitly that Lamarck, in his address of 1790, changed the name of the Jardin du Roi to Jardin des Plantes.[30] As the article states, "Entirely devoted to his studies, Lamarck entered into no intrigue under the falling monarchy, so he always remained in a position straitened and inferior to his merits." It was owing to this and his retired mode of life that the single-minded student of nature was not disturbed in his studies and meditations by the Revolution. And when the name of the Jardin du Roi threatened to be fatal to this establishment, it was he who presented a memoir to transform it, under the name of Jardin des Plantes, into an institution of higher instruction, with six professors. In 1793, Lakanal adopted Lamarck's plan, and, enlarging upon it, created twelve chairs for the teaching of the natural sciences. Bourguin thus puts the matter: "In June, 1793, Lakanal, having learned that 'the Vandals' (that is his expression) had demanded of the tribune of the Convention the suppression of the Royal Garden, as being an annex of the king's palace, recurred to the memoirs of Lamarck presented in 1790 and gave his plan of organization. He inspired himself with Lamarck's ideas, but enlarged upon them. Instead of six positions of professors-administrative, which Lamarck asked for, Lakanal established twelve chairs for the teaching of different branches of natural science."[31] FOOTNOTES: [22] Another intended victim of La Billarderie, whose own salary had been at the same time reduced, was Faujas de Saint-Fond, one of the founders of geology. But his useful discoveries in economic geology having brought him distinction, the king had generously pensioned him, and he was retained in office on the printed _État_ distributed by the Committee of Finance. (Hamy, _l. c._, p. 29.) [23] Hamy, _l. c._, p. 29. This brochure, of which I possess a copy, is a small quarto pamphlet of fifteen pages, signed, on the last page, "_J. B. Lamarck, ancien Officier au Régiment de Beaujolais, de l'Académie des Sciences de Paris, Botaniste attaché au Cabinet d'Histoire Naturelle du Jardin des Plantes_." [24] Hamy, _l. c._, p. 31; also _Pièces Justificatives_, Nos. 11 _et_ 12, pp. 97-101. The Intendant of the Garden was completely ignored, and his unpopularity and inefficiency led to his resignation. But meanwhile, in his letter to Condorcet, the perpetual Secretary of the Institute of France, remonstrating against the proposed suppression by the Assembly of the place of Intendant, he partially retracted his action against Lamarck, saying that Lamarck's work, "_peut être utile, mais n'est pas absolutement nécessaire_." The Intendant, as Hamy adds, knew well the value of the services rendered by Lamarck at the Royal Garden, and that, as a partial recompense, he had been appointed botanist to the museum. He also equally well knew that the author of the _Flore Française_ was in a most precarious situation and supported on his paltry salary a family of seven persons, as he was already at this time married and had five children. "But his own place was in peril, and he did not hesitate to sacrifice the poor savant whom he had himself installed as keeper of the herbarium." (Hamy, _l. c._, pp. 34, 35.) [25] The first idea of the foundation of the Jardin dates from 1626, but the actual carrying out of the conception was in 1635. The first act of installation took place in 1640. Gui de la Brosse, in order to please his high protectors, the first physicians of the king, named his establishment _Jardin des Plantes Medicinales_. It was renovated by Fagon, who was born in the Jardin, and whose mother was the niece of Gui de la Brosse. By his disinterestedness, activity, and great scientific capacity, he regenerated the garden, and under his administration flourished the great professors, Duverney, Tournefort, Geoffroy the chemist, and others (Perrier, _l. c._, p. 59). Fagon was succeeded by Buffon, "the new legislator and second founder." His Intendancy lasted from 1739 to 1788. [26] Three days after, August 30th, the report was ready, the discussion began, and the foundations of the new organization were definitely laid. "No longer any Jardin or Cabinets, but a Museum of Natural History, whose aim was clearly defined. No officers with unequal functions; all are professors and all will give instruction. They elect themselves and present to the king _a candidate for each vacant place_. _Finally, the general administration of the Museum will be confided to the officers of the establishment_, this implying the suppression of the Intendancy." (Hamy, _l. c._, p. 37.) [27] Hamy, _l. c._, p. 37. The Faubourg Saint Victor was a part of the Quartier Latin, and included the Jardin des Plantes. [28] _Devis de la Dépense du Jardin National des Plantes et du Cabinet d'Histoire Naturelle pour l'Année 1793_, presented to the National Convention by Citoyen Bernardin de Saint-Pierre. In it appeared a note relative to Lamarck, which, after stating that, though full of zeal and of knowledge of botany, his time was not entirely occupied; that for two months he had written him in regard to the duties of his position; referred to the statements of two of his seniors, who repeated the old gossip as to the claim of La Billarderie that his place was useless, and also found fault with him for not recognizing the artificial system of Linné in the arrangement of the herbarium, added: "However, desirous of retaining M. La Marck, father of six children, in the position which he needs, and not wishing to let his talents be useless, after several conversations with the older officers of the Jardin, I have believed that, M. Desfontaines being charged with the botanical lectures in the school, and M. Jussieu in the neighborhood of Paris, it would be well to send M. La Marck to herborize in some parts of the kingdom, in order to complete the French flora, as this will be to his taste, and at the same time very useful to the progress of botany; thus everybody will be employed and satisfied."--Perrier, _Lamarck et le Transformisme Actuel_, pp. 13, 14. (Copied from the National Archives.) "The life of Bernardin de St. Pierre (1737-1814) was nearly as irregular as that of his friend and master [Rousseau]. But his character was essentially crafty and selfish, like that of many other sentimentalists of the first order." (Morley's _Rousseau_, p. 437, footnote.) [29] Joseph Lakanal was born in 1762, and died in 1845. He was a professor of philosophy in a college of the Oratory, and doctor of the faculty at Angers, when in 1792 he was sent as a representative (_député_) to the National Convention, and being versed in educational questions he was placed on the Committee of Public Instruction and elected its president. He was the means, as Hamy states, of saving from a lamentable destruction, by rejuvenizing them, the scientific institutions of ancient France. During the Revolution he voted for the death of Louis XVI. Lakanal also presented a plan of organization of a National Institute, what is now the Institut de France, and was charged with designating the first forty-eight members, who should elect all the others. He was by the first forty-eight thus elected. Proscribed as a regicide at the second restoration, he sailed for the United States, where he was warmly welcomed by Jefferson. The United States Congress voted him five hundred acres of land. The government of Louisiana offered him the presidency of its university, which, however, he did not accept. In 1825 he went to live on the shores of Mobile Bay on land which he purchased from the proceeds of the sale of the land given him by Congress. Here he became a pioneer and planter. In 1830 he manifested a desire to return to his native country, and offered his services to the new government, but received no answer and was completely ignored. But two years later, thanks to the initiative of Geoffroy St. Hilaire, who was the means of his reëlection to the French Academy, he decided to return, and did so in 1837. He lived in retirement in Paris, where he occupied himself until his death in 1845 in writing a book entitled _Séjour d'un Membre de l'Institut de France aux États-Unis pendant vingt-deux ans_. The manuscript mysteriously disappeared, no trace of it ever having been found. (Larousse, _Grand Dictionnaire Universel_, Art. LAKANAL.) His bust now occupies a prominent place among those of other great men in the French Academy of Sciences. [30] This is seen to be the case by the title of the pamphlet: _Mémoire sur les Cabinets d'Histoire Naturelle, et particulièrement sur celui du Jardin des Plantes_. [31] Bourguin also adds that "on one point Lamarck, with more foresight, went farther than Lakanal. He had insisted on the necessity of the appointment of four demonstrators for zoölogy. In the decree of June 10, 1793, they were even reduced to two. Afterwards they saw that this number was insufficient, and to-day (1863) the department of zoölogy is administered at the museum by four professors, in conformity with the division indicated by Lamarck." CHAPTER IV PROFESSOR OF INVERTEBRATE ZOÖLOGY AT THE MUSEUM Lamarck's career as a botanist comprised about twenty-five years. We now come to the third stage of his life--Lamarck the zoölogist and evolutionist. He was in his fiftieth year when he assumed the duties of his professorship of the zoölogy of the invertebrate animals; and at a period when many men desire rest and freedom from responsibility, with the vigor of an intellectual giant Lamarck took upon his shoulders new labors in an untrodden field both in pure science and philosophic thought. It was now the summer of 1793, and on the eve of the Reign of Terror, when Paris, from early in October until the end of the year, was in the deadliest throes of revolution. The dull thud of the guillotine, placed in front of the Tuileries, in the Place de la Revolution, which is now the Place de la Concorde, a little to the east of where the obelisk of Luxor now stands, could almost be heard by the quiet workers in the Museum, for sansculottism in its most aggressive and hideous forms raged not far from the Jardin des Plantes, then just on the border of the densest part of the Paris of the first Revolution. Lavoisier, the founder of modern chemistry, was guillotined some months later. The Abbé Haüy, the founder of crystallography, had been, the year previous, rescued from prison by young Geoffroy St. Hilaire, his neck being barely saved from the gleaming axe. Roland, the friend of science and letters, had been so hunted down that at Rouen, in a moment of despair, on hearing of his wife's death, he thrust his sword-cane through his heart. Madame Roland had been beheaded, as also a cousin of her husband, and we can well imagine that these fateful summer and autumn days were scarcely favorable to scientific enterprises.[32] Still, however, amid the loud alarums of this social tempest, the Museum underwent a new birth which proved not to be untimely. The Minister of the Interior (Garat) invited the professors of the Museum to constitute an assembly to nominate a director and a treasurer, and he begged them to present extracts of their deliberations for him to send to the executive council, "under the supervision of which the National Museum is for the future placed;" though in general the assembly only reported to the Minister matters relating to the expenses, the first annual grant of the Museum being 100,000 livres. Four days after, June 14th, the assembly met and adopted the name of the establishment in the following terms: _Muséum d'Histoire Naturelle décrété par la Convention Nationale le 10 Juin, 1793_; and at a meeting held on the 9th of July the assembly definitely organized the first bureau, with Daubenton as director, Thouin treasurer, and Desfontaines secretary. Lamarck, as the records show, was present at all these meetings, and at the first one, June 14th, Lamarck and Fourcroy were designated as commissioners for the formation of the Museum library. All this was done without the aid or presence of Bernardin de Saint-Pierre, the Intendant. The Minister of the Interior, meanwhile, had communicated to him the decision of the National Convention, and invited him to continue his duties up to the moment when the new organization should be established. After remaining in his office until July 9th, he retired from the Museum August 7th following, and finally withdrew to the country at Essones. The organization of the Museum is the same now as in 1793, having for over a century been the chief biological centre of France, and with its magnificent collections was never more useful in the advancement of science than at this moment. Let us now look at the composition of the assembly of professors, which formed the Board of Administration of the Museum at the time of his appointment. The associates of Lamarck and Geoffroy St. Hilaire, who had already been connected with the Royal Garden and Cabinet, were Daubenton, Thouin, Desfontaines, Portal, and Mertrude. The Nestor of the faculty was Daubenton, who was born in 1716. He was the collaborator of Buffon in the first part of his _Histoire Naturelle_, and the author of treatises on the mammals and of papers on the bats and other mammals, also on reptiles, together with embryological and anatomical essays. Thouin, the professor of horticulture, was the veteran gardener and architect of the Jardin des Plantes, and withal a most useful man. He was affable, modest, genial, greatly beloved by his students, a man of high character, and possessing much executive ability. A street near the Jardin was named after him. He was succeeded by Bosc. Desfontaines had the chair of botany, but his attainments as a botanist were mediocre, and his lectures were said to have been tame and uninteresting. Portal taught human anatomy, while Mertrude lectured on vertebrate anatomy; his chair was filled by Cuvier in 1795. Of this group Lamarck was _facile princeps_, as he combined great sagacity and experience as a systematist with rare intellectual and philosophic traits. For this reason his fame has perhaps outlasted that of his young contemporary, Geoffroy St. Hilaire. The necessities of the Museum led to the division of the chair of zoölogy, botany being taught by Desfontaines. And now began a new era in the life of Lamarck. After twenty-five years spent in botanical research he was compelled, as there seemed nothing else for him to undertake, to assume charge of the collection of invertebrate animals, and to him was assigned that enormous, chaotic mass of forms then known as molluscs, insects, worms, and microscopic animals. Had he continued to teach botany, we might never have had the Lamarck of biology and biological philosophy. But turned adrift in a world almost unexplored, he faced the task with his old-time bravery and dogged persistence, and at once showed the skill of a master mind in systematic work. The two new professorships in zoölogy were filled, one by Lamarck, previously known as a botanist, and the other by the young Étienne Geoffroy St. Hilaire, then twenty-two years old, who was at that time a student of Haüy, and in charge of the minerals, besides teaching mineralogy with especial reference to crystallography. To Geoffroy was assigned the four classes of vertebrates, but in reality he only occupied himself with the mammals and birds. Afterwards Lacépède[33] took charge of the reptiles and fishes. On the other hand, Lamarck's field comprised more than nine-tenths of the animal kingdom. Already the collections of insects, crustacea, worms, molluscs, echinoderms, corals, etc., at the Museum were enormous. At this time France began to send out those exploring expeditions to all parts of the globe which were so numerous and fruitful during the first third of the nineteenth century. The task of arranging and classifying single-handed this enormous mass of material was enough to make a young man quail, and it is a proof of the vigor, innate ability, and breadth of view of the man that in this pioneer work he not only reduced to some order this vast horde of forms, but showed such insight and brought about such radical reforms in zoölogical classification, especially in the foundation and limitation of certain classes, an insight no one before him had evinced. To him and to Latreille much of the value of the _Règne Animal_ of Cuvier, as regards invertebrate classes, is due. The exact title of the chair held by Lamarck is given in the _État_ of persons attached to the National Museum of Natural History at the date of the 1er messidor, an II. of the Republic (1794), where he is mentioned as follows: "LAMARCK--fifty years old; married for the second time; wife _enceinte_; six children; professor of zoölogy, of insects, of worms, and microscopic animals." His salary, like that of the other professors, was put at 2,868 livres, 6 sous, 8 deniers.[34] Étienne Geoffroy St. Hilaire[35] has related how the professorship was given to Lamarck. "The law of 1793 had prescribed that all parts of the natural sciences should be equally taught. The insects, shells, and an infinity of organisms--a portion of creation still almost unknown--remained to be treated in such a course. A desire to comply with the wishes of his colleagues, members of the administration, and without doubt, also, the consciousness of his powers as an investigator, determined M. de Lamarck: this task, so great, and which would tend to lead him into numberless researches; this friendless, unthankful task he accepted--courageous resolution, which has resulted in giving us immense undertakings and great and important works, among which posterity will distinguish and honor forever the work which, entirely finished and collected into seven volumes, is known under the name of _Animaux sans Vertèbres_." Before his appointment to this chair Lamarck had devoted considerable attention to the study of conchology, and already possessed a rather large collection of shells. His last botanical paper appeared in 1800, but practically his botanical studies were over by 1793. During the early years of the Revolution, namely, from 1789 to and including 1791, Lamarck published nothing. Whether this was naturally due to the social convulsions and turmoil which raged around the Jardin des Plantes, or to other causes, is not known. In 1792, however, Lamarck and his friends and colleagues, Bruguière, Olivier, and the Abbé Haüy, founded the _Journal d'Histoire Naturelle_, which contains nineteen botanical articles, two on shells, besides one on physics, by Lamarck. These, with many articles by other men of science, illustrated by plates, indicate that during the years of social unrest and upheaval in Paris, and though France was also engaged in foreign wars, the philosophers preserved in some degree, at least, the traditional calm of their profession, and passed their days and nights in absorption in matters biological and physical. In 1801 appeared his _Système des Animaux sans Vertèbres_, preceded by the opening discourse of his lectures on the lower animals, in which his views on the origin of species were first propounded. During the years 1793-1798, or for a period of six years, he published nothing on zoölogy, and during this time only one paper appeared, in 1798, on the influence of the moon on the earth's atmosphere. But as his memoirs on fire and on sound were published in 1798, it is evident that his leisure hours during this period, when not engaged in museum work and the preparation of his lectures, were devoted to meditations on physical and meteorological subjects, and most probably it was towards the end of this period that he brooded over and conceived his views on organic evolution. It appears that he was led, in the first place, to conchological studies through his warm friendship for a fellow naturalist, and this is one of many proofs of his affectionate, generous nature. The touching story is told by Étienne Geoffroy St. Hilaire.[36] "It was impossible to assign him a professorship of botany. M. de Lamarck, then forty-nine years old, accepted this change in his scientific studies to take charge of that which everybody had neglected; because it was, indeed, a heavy load, this branch of natural history, where, with so varied relations, everything was to be created. On one group he was a little prepared, but it was by accident; a self-sacrifice to friendship was the cause. For it was both to please his friend Bruguière as well as to penetrate more deeply into the affections of this very reserved naturalist, and also to converse with him in the only language which he wished to hear, which was restricted to conversations on shells, that M. de Lamarck had made some conchological studies. Oh, how, in 1793, did he regret that his friend had gone to Persia! He had wished, he had planned, that he should take the professorship which it was proposed to create. He would at least supply his place; it was in answer to the yearnings of his soul, and this affectionate impulse became a fundamental element in the nature of one of the greatest of zoölogical geniuses of our epoch." Once settled in his new line of work, Lamarck, the incipient zoölogist, at a period in life when many students of less flexible and energetic natures become either hide-bound and conservative, averse to taking up a different course of study, or actually cease all work and rust out--after a half century of his life had passed, this rare spirit, burning with enthusiasm, charged like some old-time knight or explorer into a new realm and into "fresh fields and pastures new." His spirit, still young and fresh after nearly thirty years of mental toil, so unrequited in material things, felt a new stimulus as he began to investigate the lower animals, so promising a field for discovery. He said himself: "That which is the more singular is that the most important phenomena to be considered have been offered to our meditations only since the time when attention has been paid to the animals least perfect, and when researches on the different complications of the organization of these animals have become the principal foundation of their study. It is not less singular to realize that it was almost always from the examination of the smallest objects which nature presents to us, and that of considerations which seem to us the most minute, that we have obtained the most important knowledge to enable us to arrive at the discovery of her laws, and to determine her course." After a year of preparation he opened his course at the Museum in the spring of 1794. In his introductory lecture, given in 1803, after ten years of work on the lower animals, he addressed his class in these words: "Indeed it is among those animals which are the most multiplied and numerous in nature, and the most ready to regenerate themselves, that we should seek the most instructive facts bearing on the course of nature, and on the means she has employed in the creation of her innumerable productions. In this case we perceive that, relatively to the animal kingdom, we should chiefly devote our attention to the invertebrate animals, because their enormous multiplicity in nature, the singular diversity of their systems of organization and of their means of multiplication, their increasing simplification, and the extreme fugacity of those which compose the lowest orders of these animals, show us, much better than the higher animals, the true course of nature, and the means which she has used and which she still unceasingly employs to give existence to all the living bodies of which we have knowledge." During this decade (1793-1803) and the one succeeding, Lamarck's mind grew and expanded. Before 1801, however much he may have brooded over the matter, we have no utterances in print on the transformation theory. His studies on the lower animals, and his general knowledge of the vertebrates derived from the work of his contemporaries and his observations in the Museum and menagerie, gave him a broad grasp of the entire animal kingdom, such as no one before him had. As the result, his comprehensive mind, with its powers of rapid generalization, enabled him to appreciate the series from monad (his _ébauche_) to man, the range of forms from the simple to the complex. Even though not a comparative anatomist like Cuvier, he made use of the latter's discoveries, and could understand and appreciate the gradually increasing complexity of forms; and, unlike Cuvier, realize that they were blood relations, and not separate, piece-meal creations. Animal life, so immeasurably higher than vegetable forms, with its highly complex physiological functions and varied means of reproduction, and the relations of its forms to each other and to the world around, affords facts for evolution which were novel to Lamarck, the descriptive botanist. [Illustration: BIRTHPLACE OF LAMARCK. REAR VIEW, FROM THE WEST] [Illustration: MAISON DE BUFFON, IN WHICH LAMARCK LIVED IN PARIS. 1793-1829] In accordance with the rules of the Museum, which required that all the professors should be lodged within the limits of the Jardin, the choice of lodgings being given to the oldest professors, Lamarck, at the time of his appointment, took up his abode in the house now known as the Maison de Buffon, situated on the opposite side of the Jardin des Plantes from the house afterwards inhabited by Cuvier, and in the angle between the Galerie de Zoologie and the Museum library.[37] With little doubt the windows of his study, where his earlier addresses, the _Recherches sur l'Organisation des Corps Vivans_, and the _Philosophie Zoologique_, were probably written, looked out upon what is now the court on the westerly side of the house, that facing the Rue Geoffroy St. Hilaire. At the time of his entering on his duties as professor of zoölogy, Lamarck was in his fiftieth year. He had married twice and was the father of six children, and without fortune. He married for a third, and afterwards for a fourth time, and in all, seven children were born to him, as in the year (1794) the minute referring to his request for an indemnity states: "Il est chargé de sept enfans dont un est sur les vaisseaux de la République." Another son was an artist, as shown by the records of the Assembly of the Museum for September 23, 1814, when he asked for a chamber in the lodgings of Thouin, for the use of his son, "_peintre_." Geoffroy St. Hilaire, in 1829, spoke of one of his sons, M. Auguste de Lamarck, as a skilful and highly esteemed engineer of Ponts-et-Chaussées, then advantageously situated. But man cannot live by scientific researches and philosophic meditations alone. The history of Lamarck's life is painful from beginning to end. With his large family and slender salary he was never free from carking cares and want. On the 30 fructidor, an II. of the Republic, the National Convention voted the sum of 300,000 livres, with which an indemnity was to be paid to citizens eminent in literature and art. Lamarck had sacrificed much time and doubtless some money in the preparation and publication of his works, and he felt that he had a just claim to be placed on the list of those who had been useful to the Republic, and at the same time could give proof of their good citizenship, and of their right to receive such indemnity or appropriation. Accordingly, in 1795 he sent in a letter, which possesses much autobiographical interest, to the Committee of Public Instruction, in which he says: "During the twenty-six years that he has lived in Paris the citizen Lamarck has unceasingly devoted himself to the study of natural history, and particularly botany. He has done it successfully, for it is fifteen years since he published under the title of _Flore Française_ the history and description of the plants of France, with the mention of their properties and of their usefulness in the arts; a work printed at the expense of the government, well received by the public, and which now is much sought after and very rare." He then describes his second great botanical undertaking, the _Encyclopædia and Illustration of Genera_, with nine hundred plates. He states that for ten years past he has kept busy "a great number of Parisian artists, three printing presses for different works, besides delivering a course of lectures." The petition was granted. At about this period a pension of twelve hundred francs from the Academy of Sciences, and which had increased to three thousand francs, had ceased eighteen months previously to be paid to him. But at the time (an II.) Lamarck was "chargé de sept enfans," and this appropriation was a most welcome addition to his small salary. The next year (an III.) he again applied for a similar allowance from the funds providing an indemnity for men of letters and artists "whose talents are useful to the Republic." Again referring to the _Flore Française_, and his desire to prepare a second edition of it, and his other works and travels in the interest of botanical science, he says: "If I had been less overburdened by needs of all kinds for some years, and especially since the suppression of my pension from the aforesaid Academy of Sciences, I should prepare the second edition of this useful work; and this would be, without doubt, indeed, the opportunity of making a new present to my country. "Since my return to France I have worked on the completion of my great botanical enterprises, and indeed for about ten years past my works have obliged me to keep in constant activity a great number of artists, such as draughtsmen, engravers, and printers. But these important works that I have begun, and have in a well-advanced state, have been in spite of all my efforts suspended and practically abandoned for the last ten years. The loss of my pension from the Academy of Sciences and the enormous increase in the price of articles of subsistence have placed me, with my numerous family, in a state of distress which leaves me neither the time nor the freedom from care to cultivate science in a fruitful way." Lamarck's collection of shells, the accumulation of nearly thirty years,[38] was purchased by the government at the price of five thousand livres. This sum was used by him to balance the price of a national estate for which he had contracted by virtue of the law of 28 ventôse de l'an IV.[39] This little estate, which was the old domain of Beauregard, was a modest farm-house or country-house at Héricourt-Saint-Samson, in the Department of Seine-et-Oise, not far to the northward of Beauvais, and about fifty miles from Paris. It is probable that as a proprietor of a landed property he passed the summer season, or a part of it, on this estate. This request was, we may believe, made from no unworthy or mercenary motive, but because he thought that such an indemnity was his due. Some years after (in 1809) the chair of zoölogy, newly formed by the Faculté des Sciences in Paris, was offered to him. Desirable as the salary would have been in his straitened circumstances, he modestly refused the offer, because he felt unable at that time of life (he was, however, but sixty-five years of age) to make the studies required worthily to occupy the position. One of Lamarck's projects, which he was never able to carry out, for it was even then quite beyond the powers of any man single-handed to undertake, was his _Système de la Nature_. We will let him describe it in his own words, especially since the account is somewhat autobiographical. It is the second memoir he addressed to the Committee of Public Instruction of the National Convention, dated 4 vendémiaire, l'an III. (1795): "In my first memoir I have given you an account of the works which I have published and of those which I have undertaken to contribute to the progress of natural history; also of the travels and researches which I have made. "But for a long time I have had in view a very important work--perhaps better adapted for education in France than those I have already composed or undertaken--a work, in short, which the National Convention should without doubt order, and of which no part could be written so advantageously as in Paris, where are to be found abundant means for carrying it to completion. "This is a _Système de la Nature_, a work analogous to the _Systema naturæ_ of Linnæus, but written in French, and presenting the picture complete, concise, and methodical, of all the natural productions observed up to this day. This important work (of Linnæus), which the young Frenchmen who intend to devote themselves to the study of natural history always require, is the object of speculations by foreign authors, and has already passed through thirteen different editions. Moreover, their works, which, to our shame, we have to use, because we have none written expressly for us, are filled (especially the last edition edited by Gmelin) with gross mistakes, omissions of double and triple occurrence, and errors in synonymy, and present many generic characters which are inexact or imperceptible and many series badly divided, or genera too numerous in species, and difficulties insurmountable to students. "If the Committee of Public Instruction had the time to devote any attention to the importance of my project, to the utility of publishing such a work, and perhaps to the duty prescribed by the national honor, I would say to it that, after having for a long time reflected and meditated and determined upon the most feasible plan, finally after having seen amassed and prepared the most essential materials, I offer to put this beautiful project into execution. I have not lost sight of the difficulties of this great enterprise. I am, I believe, as well aware of them, and better, than any one else; but I feel that I can overcome them without descending to a simple and dishonorable compilation of what foreigners have written on the subject. I have some strength left to sacrifice for the common advantage; I have had some experience and practice in writing works of this kind; my herbarium is one of the richest in existence; my numerous collection of shells is almost the only one in France the specimens of which are determined and named according to the method adopted by modern naturalists--finally, I am in a position to profit by all the aid which is to be found in the National Museum of Natural History. With these means brought together, I can then hope to prepare in a suitable manner this interesting work. "I had at first thought that the work should be executed by a society of naturalists; but after having given this idea much thought, and having already the example of the new encyclopædia, I am convinced that in such a case the work would be very defective in arrangement, without unity or plan, without any harmony of principles, and that its composition might be interminable. "Written with the greatest possible conciseness, this work could not be comprised in less than eight volumes in 8vo, namely: One volume for the quadrupeds and birds; one volume for the reptiles and fishes; two volumes for the insects; one volume for the worms (the molluscs, madrepores, lithophytes, and naked worms); two volumes for the plants; one volume for the minerals: eight volumes in all. "It is impossible to prepare in France a work of this nature without having special aid from the nation, because the expense of printing (on account of the enormous quantity of citations and figures which it would contain) would be such that any arrangement with the printer or the manager of the edition could not remunerate the author for writing such an immense work. "If the nation should wish to print the work at its own expense, and then give to the author the profits of the sale of this edition, the author would be very much pleased, and would doubtless not expect any further aid. But it would cost the nation a great deal, and I believe that this useful project could be carried through with greater economy. "Indeed, if the nation will give me twenty thousand francs, in a single payment, I will take the whole responsibility, and I agree, if I live, that before the expiration of seven years the _Système de la Nature_ in French, with the complemental addition, the corrections, and the convenient explanations, shall be at the disposition of all those who love or study natural history." FOOTNOTES: [32] Most men of science of the Revolution, like Monge and others, were advanced republicans, and the Chevalier Lamarck, though of noble birth, was perhaps not without sympathy with the ideas which led to the establishment of the republic. It is possible that in his walks and intercourse with Rousseau he may have been inspired with the new notions of liberty and equality first promulgated by that philosopher. His studies and meditations were probably not interrupted by the events of the Terror. Stevens, in his history of the French Revolution, tells us that Paris was never gayer than in the summer of 1793, and that during the Reign of Terror the restaurants, _cafés_, and theatres were always full. There were never more theatres open at the same period than then, though no single great play or opera was produced. Meanwhile the great painter David at this time built up a school of art and made that city a centre for art students. Indeed the Revolution was "a grand time for enthusiastic young men," while people in general lived their ordinary lives. There is little doubt, then, that the savants, except the few who were occupied by their duties as members of the _Convention Nationale_, worked away quietly at their specialties, each in his own study or laboratory or lecture-room. [33] Bern. Germ. Étienne, Comte de Lacépède, born in 1756, died in 1825, was elected professor of the zoölogy of "quadrupedes ovipares, reptiles, et poissons," January 12, 1795 (Records of the Museum). He was the author of works on amphibia, reptiles, and mammals, forming continuations of Buffon's _Histoire Naturelle_. He also published _Histoire Naturelle des Poissons_ (1798-1803), _Histoire des Cétacés_ (1804), and _Histoire Naturelle de l'Homme_ (1827), _Les Ages de la Nature et Histoire de l'Espèce Humaine_, tome 2, 1830. [34] Perrier, _l. c._, p. 14. [35] _Fragments Biographiques_, p. 214. [36] _Fragments Biographiques_, p. 213. [37] A few years ago, when we formed the plan of writing his life, we wrote to friends in Paris for information as to the exact house in which Lamarck lived, and received the answer that it was unknown; another proof of the neglect and forgetfulness that had followed Lamarck so many years after his death, and which was even manifested before he died. Afterwards Professor Giard kindly wrote that by reference to the _procès verbaux_ of the Assembly, it had been found by Professor Hamy that he had lived in the house of Buffon. The house is situated at the corner of Rue de Buffon and Rue Geoffroy St. Hilaire. The courtyard facing Rue Geoffroy St. Hilaire bears the number 2 Rue de Buffon, and is in the angle between the Galerie de Zoologie and the Bibliothèque. The edifice is a large four-storied one. Lamarck occupied the second _étage_, what we should call the third story; it was first occupied by Buffon. His bedroom, where he died, was on the _premier étage_. It was tenanted by De Quatrefages in his time, and is at present occupied by Professor G. T. Hamy; Professor L. Vaillant living in the first _étage_, or second story, and Dr. J. Deniker, the _bibliothécaire_ and learned anthropologist, in the third. The second _étage_ was, about fifty years ago (1840-50), renovated for the use of Fremy the chemist, so that the exact room occupied by Lamarck as a study cannot be identified. This ancient house was originally called _La Croix de Fer_, and was built about two centuries before the foundation of the Jardin du Roi. It appears from an inspection of the notes on the titles and copies of the original deeds, preserved in the Archives, and kindly shown me by Professor G. T. Hamy, the Archivist of the Museum, that this house was erected in 1468, the deed being dated _1xbre_, 1468. The house is referred to as _maison ditte La Croix de Fer_ in deeds of 1684, 1755, and 1768. It was sold by Charles Roger to M. le Compte de Buffon, March 23, 1771. One of the old gardens overlooked by it was called _de Jardin de la Croix_. It was originally the first structure erected on the south side of the Jardin du Roi. [38] In the "avertissement" to his _Système des Animaux sans Vertèbres_ (1801), after stating that he had at his disposition the magnificent collection of invertebrate animals of the museum, he refers to his private collection as follows: "Et une autre assez riche que j'ai formée moi-même par près de trente années de recherches," p. vii. Afterwards he formed another collection of shells named according to his system, and containing a part of the types described in his _Histoire Naturelle des Animaux sans Vertèbres_ and in his minor articles. This collection the government did not acquire, and it is now in the museum at Geneva. The Paris museum, however, possesses a good many of the Lamarckian types, which are on exhibition (Perrier, _l. c._, p. 20). [39] _Lettre du Ministre des Finances (de Ramel) au Ministre de l'Intérieur_ (13 pr. an V.). See Perrier, _l. c._, p. 20. CHAPTER V LAST DAYS AND DEATH Lamarck's life was saddened and embittered by the loss of four wives, and the pangs of losing three of his children;[40] also by the rigid economy he had to practise and the unending poverty of his whole existence. A very heavy blow to him and to science was the loss, at an advanced age, of his eyesight. It was, apparently, not a sudden attack of blindness, for we have hints that at times he had to call in Latreille and others to aid him in the study of the insects. The continuous use of the magnifying lens and the microscope, probably, was the cause of enfeebled eyesight, resulting in complete loss of vision. Duval[41] states that he passed the last ten years of his life in darkness; that his loss of sight gradually came on until he became completely blind. In the reports of the meetings of the Board of Professors there is but one reference to his blindness. Previous to this we find that, at his last appearance at these sessions--_i.e._, April 19, 1825--since his condition did not permit him to give his course of lectures, he had asked M. Latreille to fill his place; but such was the latter's health, he proposed that M. Audouin, sub-librarian of the French Institute, should lecture in his stead, on the invertebrate animals. This was agreed to. The next reference, and the only explicit one, is that in the records for May 23, 1826, as follows: "Vu la cécité dont M. de Lamarck est frappé, M. Bosc[42] continuera d'exercer sur les parties confiert à M. Audouin la surveillance attribuée au Professeur." But, according to Duval, long before this he had been unable to use his eyes. In his _Système analytique des Connaissances positives de l'Homme_, published in 1820, he refers to the sudden loss of his eyesight. Even in advanced life Lamarck seems not to have suffered from ill-health, despite the fact that he apparently during the last thirty years of his life lived in a very secluded way. Whether he went out into the world, to the theatre, or even went away from Paris and the Museum into the country in his later years, is a matter of doubt. It is said that he was fond of novels, his daughters reading to him those of the best French authors. After looking with some care through the records of the sessions of the Assembly of Professors, we are struck with the evidences of his devotion to routine museum work and to his courses of lectures. At that time the Museum sent out to the _Écoles centrales_ of the different departments of France named collections made up from the duplicates, and in this sort of drudgery Lamarck took an active part. He also took a prominent share in the business of the Museum, in the exchange and in the purchase of specimens and collections in his department, and even in the management of the menagerie. Thus he reported on the dentition of the young lions (one dying from teething), on the illness and recovery of one of the elephants, on the generations of goats and kids in the park; also on a small-sized bull born of a small cow covered by a Scottish bull, the young animal having, as he states, all the characters of the original. For one year (1794) he was secretary of the Board of Professors of the Museum.[43] The records of the meetings from 4 vendémiaire, l'an III., until 4 vendémiaire, l'an IV., are each written in his bold, legible handwriting or signed by him. He signed his name _Lamarck_, this period being that of the first republic. Afterwards, in the records, his name is written _De Lamarck_. He was succeeded by É. Geoffroy St. Hilaire, who signed himself plain _Geoffroy_. In 1802 he acted as treasurer of the Assembly, and again for a period of six years, until and including 1811, when he resigned, the reason given being: "Il s'occupe depuis six ans et que ses travaux et son age lui rendent penibles." Lamarck was extremely regular in his attendance at these meetings. From 1793 until 1818 he rarely, if ever, missed a meeting. We have only observed in the records of this long period the absence of his name on two or three occasions from the list of those present. During 1818 and the following year it was his blindness which probably prevented his regular attendance. July 15, 1818, he was present, and presented the fifth volume of his _Animaux sans Vertèbres_; and August 31, 1819, he was present[44] and laid before the Assembly the sixth volume of the same great work. [Illustration: PORTRAIT OF LAMARCK, WHEN OLD AND BLIND, IN THE COSTUME OF A MEMBER OF THE INSTITUTE, ENGRAVED IN 1824.] From the observations of the records we infer that Lamarck never had any long, lingering illness or suffered from overwork, though his life had little sunshine or playtime in it. He must have had a strong constitution, his only infirmity being the terrible one (especially to an observer of nature) of total blindness. Lamarck's greatest work in systematic zoölogy would never have been completed had it not been for the self-sacrificing spirit and devotion of his eldest daughter. A part of the sixth and the whole of the last volume of the _Animaux sans Vertèbres_ were presented to the Assembly of Professors September 10, 1822. This volume was dictated to and written out by one of his daughters, Mlle. Cornelie De Lamarck. On her the aged savant leaned during the last ten years of his life--those years of failing strength and of blindness finally becoming total. The frail woman accompanied him in his hours of exercise, and when he was confined to his house she never left him. It is stated by Cuvier, in his eulogy, that at her first walk out of doors after the end came she was nearly overcome by the fresh air, to which she had become so unaccustomed. She, indeed, practically sacrificed her life to her father. It is one of the rarest and most striking instances of filial devotion known in the annals of science or literature, and is a noticeable contrast to the daughters of the blind Milton, whose domestic life was rendered unhappy by their undutifulness, as they were impatient of the restraint and labors his blindness had imposed upon them. Besides this, the seventh volume is a voluminous scientific work, filled with very dry special details, making the labor of writing out from dictation, of corrections and preparation for the press, most wearisome and exhausting, to say nothing of the corrections of the proof-sheets, a task which probably fell to her--work enough to break down the health of a strong man. It was a natural and becoming thing for the Assembly of Professors of the Museum, in view of the "malheureuse position de la famille," to vote to give her employment in the botanical laboratory in arranging and pasting the dried plants, with a salary of 1,000 francs. Of the last illness of Lamarck, and the nature of the sickness to which he finally succumbed, there is no account. It is probable that, enfeebled by the weakness of extreme old age, he gradually sank away without suffering from any acute disease. The exact date of his death has been ascertained by Dr. Mondière,[45] with the aid of M. Saint-Joanny, archiviste du Dèpartment de la Seine, who made special search for the record. The "acte" states that December 28, 1829, Lamarck, then a widower, died in the Jardin du Roi, at the age of eighty-five years. The obsequies, as stated in the _Moniteur Universel_ of Paris for December 23, 1829, were celebrated on the Sunday previous in the Church of Saint-Médard, his parish. From the church the remains were borne to the cemetery of Montparnasse. At the interment, which took place December 30, M. Latreille, in the name of the Academy of Sciences, and M. Geoffroy St. Hilaire, in the name and on behalf of his colleagues, the Professors of the Museum of Natural History, pronounced eulogies at the grave. The eulogy prepared by Cuvier, and published after his death, was read at a session of the Academy of Sciences, by Baron Silvestre, November 26, 1832. With the exception of these formalities, the great French naturalist, "the Linné of France," was buried as one forgotten and unknown. We read with astonishment, in the account by Dr. A. Mondière, who made zealous inquiries for the exact site of the grave of Lamarck, that it is and forever will be unknown. It is a sad and discreditable, and to us inexplicable, fact that his remains did not receive decent burial. They were not even deposited in a separate grave, but were thrown into a trench apparently situated apart from the other graves, and from which the bones of those thrown there were removed every five years. They are probably now in the catacombs of Paris, mingled with those of the thousands of unknown or paupers in that great ossuary.[46] Dr. Mondière's account is as follows. Having found in the _Moniteur_ the notice of the burial services, as above stated, he goes on to say: "Armed with this document, I went again to the cemetery of Montparnasse, where I fortunately found a conservator, M. Lacave, who is entirely _au courant_ with the question of transformism. He therefore interested himself in my inquiries, and, thanks to him, I have been able to determine exactly where Lamarck had been buried. I say had been, because, alas! he had been simply placed in a _trench off on one side_ (_fosse à part_), that is to say, one which should change its occupant at the end of five years. Was it negligence, was it the jealousy of his colleagues, was it the result of the troubles of 1830? In brief, there had been no permission granted to purchase a burial lot. The bones of Lamarck are probably at this moment mixed with those of all the other unknown which lie there. What had at first led us into an error is that we made the inquiries under the name of Lamarck instead of that of de Monnet. In reality, the register of inscription bears the following mention: "'De Monnet de Lamarck buried this 20 December 1829 (85 years), 3d square, 1st division, 2d line, trench 22.' "At some period later, a friendly hand, without doubt, had written on the margin of the register the following information: "'To the left of M. Dassas.' "M. Lacave kindly went with us to search for the place where Lamarck had been interred, and on the register we saw this: "'Dassas, 1st division, 4th line south, No. 6 to the west, concession 1165-1829.' On arriving at the spot designated, we found some new graves, but nothing to indicate that of M. Dassas, our only mark by which we could trace the site after the changes wrought since 1829. After several ineffectual attempts, I finally perceived a flat grave, surrounded by an iron railing, and covered with weeds. Its surface seemed to me very regular, and I probed this lot. There was a gravestone there. The grave-digger who accompanied us cleared away the surface, and I confess that it was with the greatest pleasure and with deep emotion that we read the name Dassas. [Illustration: POSITION OF THE BURIAL PLACE OF LAMARCK IN THE CEMETERY OF MONTPARNASSE.] "We found the place, but unfortunately, as I have previously said, the remains of Lamarck are no longer there." Mondière added to his letter a little plan (p. 59), which he drew on the spot.[47] But the life-work of Lamarck and his theory of organic evolution, as well as the lessons of his simple and noble character, are more durable and lasting than any monument of stone or brass. His name will never be forgotten either by his own countrymen or by the world of science and philosophy. After the lapse of nearly a hundred years, and in this first year of the twentieth century, his views have taken root and flourished with a surprising strength and vigor, and his name is preëminent among the naturalists of his time. No monument exists in Montparnasse, but within the last decade, though the reparation has come tardily, the bust of Lamarck may be seen by visitors to the Jardin des Plantes, on the outer wall of the Nouvelle Galerie, containing the Museums of Comparative Anatomy, Palæontology, and Anthropology. Although the city of Paris has not yet erected a monument to its greatest naturalist, some public recognition of his eminent services to the city and nation was manifested when the Municipal Council of Paris, on February 10, 1875, gave the name Lamarck to a street.[48] This is a long and not unimportant street on the hill of Montmartre in the XVIII^e _arrondissement_, and in the zone of the old stone or gypsum quarries which existed before Paris extended so far out in that direction, and from which were taken the fossil remains of the early tertiary mammals described by Cuvier. The city of Toulouse has also honored itself by naming one of its streets after Lamarck; this was due to the proposal of Professor Émile Cartailhac to the Municipal Council, which voted to this effect May 12, 1886. In the meetings of the Assembly of Professors no one took the trouble to prepare and enter minutes, however brief and formal, relative to his decease. The death of Lamarck is not even referred to in the _Procès-verbaux_. This is the more marked because there is an entry in the same records for 1829, and about the same date, of an extraordinary _séance_ held November 19, 1829, when "the Assembly" was convoked to take measures regarding the death of Professor Vauquelin relative to the choice of a candidate, Chevreul being elected to fill his chair. Lamarck's chair was at his death divided, and the two professorships thus formed were given to Latreille and De Blainville. At the session of the Assembly of Professors held December 8, 1829, Geoffroy St. Hilaire sent in a letter to the Assembly urging that the department of invertebrate animals be divided into two, and referred to the bad state of preservation of the insects, the force of assistants to care for these being insufficient. He also, in his usual tactful way, referred to the "_complaisance extrème de la parte de M. De Lamarck_" in 1793, in assenting to the reunion in a single professorship of the mass of animals then called "_insectes et vermes_." The two successors of the chair held by Lamarck were certainly not dilatory in asking for appointments. At a session of the Professors held December 22, 1829, the first meeting after his death, we find the following entry: "M. Latreille écrit pour exprimer son désir d'être présenté comme candidat à la chaire vacante par le décès de M. Lamarck et pour rappeler ses titres à cette place." M. de Blainville also wrote in the same manner: "Dans le cas que la chaire serait divisée, il demande la place de Professeur de l'histoire des animaux inarticulés. Dans le cas contraire il se présente également comme candidat, voulant, tout en respectant les droits acquis, ne pas laisser dans l'oubli ceux qui lui appartiennent." January 12, 1830, Latreille[49] was unanimously elected by the Assembly a candidate to the chair of entomology, and at a following session (February 16th) De Blainville was unanimously elected a candidate for the chair of _Molluscs, Vers et Zoophytes_, and on the 16th of March the royal ordinance confirming those elections was received by the Assembly. There could have been no fitter appointments made for those two positions. Lamarck had long known Latreille "and loved him as a son." De Blainville honored and respected Lamarck, and fully appreciated his commanding abilities as an observer and thinker. FOOTNOTES: [40] I have been unable to ascertain the names of any of his wives, or of his children, except his daughter, Cornelie. [41] "L'examen minutieux de petits animaux, analysés à l'aide d'instruments grossissants, fatigua, puis affaiblait, sa vue. Bientôt il fut complement aveugle. Il passa les dix derniers années de sa vie plongé dans les ténèbres, entouré des soins de ses deux tilles, à l'une desquelles il dictait le dernier volume de son _Histoire des Animaux sans Vertèbres_."--_Le Transformiste Lamarck_, _Bull. Soc. Anthropologie_, xii., 1889, p. 341. Cuvier, also, in his history of the progress of natural science for 1819, remarks: "M. de La Marck, malgré l'affoiblissement total de sa vue, poursuit avec un courage inaltérable la continuation de son grand ouvrage sur les animaux sans vertèbres" (p. 406). [42] Louis Auguste Guillaume Bosc, born in Paris, 1759; died in 1828. Author of now unimportant works, entitled: _Histoire Naturelle des Coquilles_ (1801); _Hist. Nat. des Vers_ (1802); _Hist. Nat. des Crustacés_ (1828), and papers on insects and plants. He was associated with Lamarck in the publication of the _Journal d'Histoire Naturelle_. During the Reign of Terror in 1793 he was a friend of Madame Roland, was arrested, but afterwards set free and placed first on the Directory in 1795. In 1798 he sailed for Charleston, S. C. Nominated successively vice-consul at Wilmington and consul at New York, but not obtaining his exequatur from President Adams, he went to live with the botanist Michaux in Carolina in his botanical garden, where he devoted himself to natural history until the quarrel in 1800 between the United States and France caused him to return to France. On his return he sent North American insects to his friends Fabricius and Olivier, fishes to Lacépède, birds to Daudin, reptiles to Latreille. Not giving all his time to public life, he devoted himself to natural history, horticulture, and agriculture, succeeding Thouin in the chair of horticulture, where he was most usefully employed until his death.--(Cuvier's _Éloge_.) [43] The first director of the Board or Assembly of Professors-administrative of the Museum was Daubenton, Lacépède being the secretary, Thouin the treasurer. Daubenton was succeeded by Jussieu; and Lacépède, first by Desfontaines and afterwards by Lamarck, who was elected secretary 18 fructidor, an II. (1794). [44] His attendance this year was infrequent. July 10, 1820, he was present and made a report relative to madrepores and molluscs. In the summer of 1821 he attended several of the meetings. August 7, 1821, he was present, and referred to the collection of shells of Struthiolaria. He was present May 23d and June 9th, when it was voted that he should enjoy the garden of the house he occupied and that a chamber should be added to his lodgings. He was frequent in attendance this year, especially during the summer months. He attended a few meetings at intervals in 1822, 1823, and only twice in 1824. At a meeting held April 19, 1825, he was present, and, stating that his condition did not permit him to lecture, asked to have Audouin take his place, as Latreille's health did not allow him to take up the work. The next week (26th) he was likewise present. On May 10 he was present, as also on June 28, October 11, and also through December, 1825. His last appearance at these business meetings was on July 11, 1828. [45] See, for the _Acte de décès_, _L'Homme_, iv. p. 289, and _Lamarck. Par un Groupe de Transformistes_, etc., p. 24. [46] Dr. Mondière in _L'Homme_, iv. p. 291, and _Lamarck. Par un Groupe de Transformistes_, p. 271. A somewhat parallel case is that of Mozart, who was buried at Vienna in the common ground of St. Marx, the exact position of his grave being unknown. There were no ceremonies at his grave, and even his friends followed him no farther than the city gates, owing to a violent storm.--(_The Century Cyclopedia of Names._) [47] Still hoping that the site of the grave might have been kept open, and desiring to satisfy myself as to whether there was possibly space enough left on which to erect a modest monument to the memory of Lamarck, I took with me the _brochure_ containing the letter and plan of Dr. Mondière to the cemetery of Montparnasse. With the aid of one of the officials I found what he told me was the site, but the entire place was densely covered with the tombs and grave-stones of later interments, rendering the erection of a stone, however small and simple, quite out of the question. [48] The Rue Lamarck begins at the elevated square on which is situated the Church of the Sacré-Coeur, now in process of erection, and from this point one obtains a commanding and very fine view overlooking the city; from there the street curves round to the westward, ending in the Avenue de Saint-Ouen, and continues as a wide and long thoroughfare, ending to the north of the cemetery of Montmartre. A neighboring street, Rue Becquerel, is named after another French savant, and parallel to it is a short street named Rue Darwin. [49] Latreille was born at Brives, November 29, 1762, and died February 6, 1833. He was the leading entomologist of his time, and to him Cuvier was indebted for the arrangement of the insects in the _Règne Animal_. His bust is to be seen on the same side of the Nouvelle Galerie in the Jardin des Plantes as those of Lamarck, Cuvier, De Blainville, and D'Orbigny. His first paper was introduced by Lamarck in 1792. In the minutes of the session of 4 thermidor, l'an VI. (July, 1798), we find this entry: "The citizen Lamarck announces that the citizen Latreille offered to the administration to work under the direction of that professor in arranging the very numerous collection of insects of the Museum, so as to place them under the eye of the public." And here he remained until his appointment. Several years (1825) before Lamarck's death he had asked to have Latreille fill his place in giving instruction. Audouin (1797-1841), also an eminent entomologist and morphologist, was appointed _aide-naturaliste-adjoint_ in charge of Mollusca, Crustacea, Worms, and Zoöphytes. He was afterwards associated with H. Milne Edwards in works on annelid worms. December 26, 1827, Latreille asked to be allowed to employ Boisduval as a _préparateur_; he became the author of several works on injurious insects and Lepidoptera. CHAPTER VI POSITION IN THE HISTORY OF SCIENCE; OPINIONS OF HIS CONTEMPORARIES AND SOME LATER BIOLOGISTS De Blainville, a worthy successor of Lamarck, in his posthumous book, _Cuvier et Geoffroy Saint-Hilaire_, pays the highest tribute to his predecessor, whose position as the leading naturalist of his time he fully and gratefully acknowledges, saying: "Among the men whose lectures I have had the advantage of hearing, I truly recognize only three masters, M. de Lamarck, M. Claude Richard, and M. Pinel" (p. 43). He also speaks of wishing to write the scientific biographies of Cuvier and De Lamarck, the two zoölogists of this epoch whose lectures he most frequently attended and whose writings he studied, and "who have exercised the greatest influence on the zoölogy of our time" (p. 42). Likewise in the opening words of the preface he refers to the rank taken by Lamarck: "The aim which I have proposed to myself in my course on the principles of zoölogy demonstrated by the history of its progress from Aristotle to our time, and consequently the plan which I have followed to attain this aim, have very naturally led me, so to speak, in spite of myself, to signalize in M. de Lamarck the expression of one of those phases through which the science of organization has to pass in order to arrive at its last term before showing its true aim. From my point of view this phase does not seem to me to have been represented by any other naturalist of our time, whatever may have been the reputation which he made during his life." He then refers to the estimation in which Lamarck was held by Auguste Comte, who, in his _Cours de Philosophie Positive_, has anticipated and even surpassed himself in the high esteem he felt for "the celebrated author of the _Philosophie Zoologique_." The eulogy by Cuvier, which gives most fully the details of the early life of Lamarck, and which has been the basis for all the subsequent biographical sketches, was unworthy of him. Lamarck had, with his customary self-abnegation and generosity, aided and favored the young Cuvier in the beginning of his career,[50] who in his _Règne Animal_ adopted the classes founded by Lamarck. Thoroughly convinced of the erroneous views of Cuvier in regard to cataclysms, he criticised and opposed them in his writings in a courteous and proper way without directly mentioning Cuvier by name or entering into any public debate with him. When the hour came for the great comparative anatomist and palæontologist, from his exalted position, to prepare a tribute to the memory of a naturalist of equal merit and of a far more thoughtful and profound spirit, to be read before the French Academy of Sciences, what a eulogy it was--as De Blainville exclaims, _et quel éloge_! It was not printed until after Cuvier's death, and then, it is stated, portions were omitted as not suitable for publication.[51] This is, we believe, the only stain on Cuvier's life, and it was unworthy of the great man. In this _éloge_, so different in tone from the many others which are collected in the three volumes of Cuvier's eulogies, he indiscriminately ridicules all of Lamarck's theories. Whatever may have been his condemnation of Lamarck's essays on physical and chemical subjects, he might have been more reserved and less dogmatic and sarcastic in his estimate of what he supposed to be the value of Lamarck's views on evolution. It was Cuvier's adverse criticisms and ridicule and his anti-evolutional views which, more than any other single cause, retarded the progress of biological science and the adoption of a working theory of evolution for which the world had to wait half a century. It even appears that Lamarck was in part instrumental in inducing Cuvier in 1795 to go to Paris from Normandy, and become connected with the Museum. De Blainville relates that the Abbé Tessier met the young zoölogist at Valmont near Fécamp, and wrote to Geoffroy that "he had just discovered in Normandy a pearl," and invited him to do what he could to induce Cuvier to come to Paris. "I made," said Geoffroy, "the proposition to my _confrères_, but I was supported, and only feebly, by M. de Lamarck, who slightly knew M. Cuvier as the author of a memoir on entomology." The eulogy pronounced by Geoffroy St. Hilaire over the remains of his old friend and colleague was generous, sympathetic, and heartfelt. "Yes [he said, in his eloquent way], for us who knew M. de Lamarck, whom his counsels have guided, whom we have found always indefatigable, devoted, occupied so willingly with the most difficult labors, we shall not fear to say that such a loss leaves in our ranks an immense void. From the blessings of such a life, so rich in instructive lessons, so remarkable for the most generous self-abnegation, it is difficult to choose. "A man of vigorous, profound ideas, and very often admirably generalized, Lamarck conceived them with a view to the public good. If he met, as often happened, with great opposition, he spoke of it as a condition imposed on every one who begins a reform. Moreover, the great age, the infirmities, but especially the grievous blindness of M. de Lamarck had reserved for him another lot. This great and strong mind could enjoy some consolation in knowing the judgment of posterity, which for him began in his own lifetime. When his last tedious days, useless to science, had arrived, when he had ceased to be subjected to rivalry, envy and passion became extinguished and justice alone remained. De Lamarck then heard impartial voices, the anticipated echo of posterity, which would judge him as history will judge him. Yes, the scientific world has pronounced its judgment in giving him the name of 'the French Linné,' thus linking together the two men who have both merited a triple crown by their works on general natural history, zoölogy and botany, and whose names, increasing in fame from age to age, will both be handed down to the remotest posterity."[52] Also in his _Études sur la Vie, les Ouvrages, et les Doctrines de Buffon_ (1838), Geoffroy again, with much warmth of affection, says: "Attacked on all sides, injured likewise by odious ridicule, Lamarck, too indignant to answer these cutting epigrams, submitted to the indignity with a sorrowful patience.... Lamarck lived a long while poor, blind, and forsaken, but not by me; I shall ever love and venerate him."[53] The following evidently heartfelt and sincere tribute to his memory, showing warm esteem and thorough respect for Lamarck, and also a confident feeling that his lasting fame was secure, is to be found in an obscure little book[54] containing satirical, humorous, but perhaps not always fair or just, characterizations and squibs concerning the professors and aid-naturalists of the Jardin des Plantes. "What head will not be uncovered on hearing pronounced the name of the man whose genius was ignored and who languished steeped in bitterness. Blind, poor, forgotten, he remained alone with a glory of whose extent he himself was conscious, but which only the coming ages will sanction, when shall be revealed more clearly the laws of organization. "Lamarck, thy abandonment, sad as it was in thy old age, is better than the ephemeral glory of men who only maintain their reputation by sharing in the errors of their time. "Honor to thee! Respect to thy memory! Thou hast died in the breach while fighting for truth, and the truth assures thee immortality." Lamarck's theoretical views were not known in Germany until many years after his death. Had Goethe, his contemporary (1749-1832), known of them, he would undoubtedly have welcomed his speculations, have expressed his appreciation of them, and Lamarck's reputation would, in his own lifetime, have raised him from the obscurity of his later years at Paris. Hearty appreciation, though late in the century, came from Ernst Haeckel, whose bold and suggestive works have been so widely read. In his _History of Creation_ (1868) he thus estimates Lamarck's work as a philosopher: "To him will always belong the immortal glory of having for the first time worked out the theory of descent, as an independent scientific theory of the first order, and as the philosophical foundation of the whole science of biology." Referring to the _Philosophie Zoologique_, he says: "This admirable work is the first connected exposition of the theory of descent carried out strictly into all its consequences. By its purely mechanical method of viewing organic nature, and the strictly philosophical proofs brought forward in it, Lamarck's work is raised far above the prevailing dualistic views of his time; and with the exception of Darwin's work, which appeared just half a century later, we know of none which we could, in this respect, place by the side of the _Philosophie Zoologique_. How far it was in advance of its time is perhaps best seen from the circumstance that it was not understood by most men, and for fifty years was not spoken of at all. Cuvier, Lamarck's greatest opponent, in his _Report on the Progress of Natural Science_, in which the most unimportant anatomical investigations are enumerated, does not devote a single word to this work, which forms an epoch in science. Goethe, also, who took such a lively interest in the French nature-philosophy and in the 'thoughts of kindred minds beyond the Rhine,' nowhere mentions Lamarck, and does not seem to have known the _Philosophie Zoologique_ at all." Again in 1882 Haeckel writes:[55] "We regard it as a truly tragic fact that the _Philosophie Zoologique_ of Lamarck, one of the greatest productions of the great literary period of the beginning of our century, received at first only the slightest notice, and within a few years became wholly forgotten.... Not until fully fifty years later, when Darwin breathed new life into the transformation views founded therein, was the buried treasure again recovered, and we cannot refrain from regarding it as the most complete presentation of the development theory before Darwin. "While Lamarck clearly expressed all the essential fundamental ideas of our present doctrine of descent; and excites our admiration at the depth of his morphological knowledge, he none the less surprises us by the prophetic (_vorausschauende_) clearness of his physiological conceptions." In his views on life, the nature of the will and reason, and other subjects, Haeckel declares that Lamarck was far above most of his contemporaries, and that he sketched out a programme of the biology of the future which was not carried out until our day. J. Victor Carus[56] also claims for Lamarck "the lasting merit of having been the first to have placed the theory (of descent) on a scientific foundation." The best, most catholic, and just exposition of Lamarck's views, and which is still worth reading, is that by Lyell Chapters XXXIV.-XXXVI. of his _Principles of Geology_, 1830, and though at that time one would not look for an acceptance of views which then seemed extraordinary and, indeed, far-fetched, Lyell had no words of satire and ridicule, only a calm, able statement and discussion of his principles. Indeed, it is well known that when, in after years, his friend Charles Darwin published his views, Lyell expressed some leaning towards the older speculations of Lamarck. Lyell's opinions as to the interest and value of Lamarck's ideas may be found in his _Life and Letters_, and also in the _Life and Letters of Charles Darwin_. In the chapter, _On the Reception of the Origin of Species_, by Huxley, are the following extracts from Lyell's _Letters_ (ii., pp. 179-204). In a letter addressed to Mantell (dated March 2, 1827), Lyell speaks of having just read Lamarck; he expresses his delight at Lamarck's theories, and his personal freedom from any objections based on theological grounds. And though he is evidently alarmed at the pithecoid origin of man involved in Lamarck's doctrine, he observes: "But, after all, what changes species may really undergo! How impossible will it be to distinguish and lay down a line beyond which some of the so-called extinct species have never passed into recent ones?" He also quotes a remarkable passage in the postscript to a letter written to Sir John Herschel in 1836: "In regard to the origination of new species, I am very glad to find that you think it probable it may be carried on through the intervention of intermediate causes." How nearly Lyell was made a convert to evolution by reading Lamarck's works may be seen by the following extracts from his letters, quoted by Huxley: "I think the old 'creation' is almost as much required as ever, but of course it takes a new form if Lamarck's views, improved by yours, are adopted." (To Darwin, March 11, 1863, p. 363.) ~ ~ ~ ~ ~ "As to Lamarck, I find that Grove, who has been reading him, is wonderfully struck with his book. I remember that it was the conclusion he (Lamarck) came to about man, that fortified me thirty years ago against the great impression which his argument at first made on my mind--all the greater because Constant Prevost, a pupil of Cuvier forty years ago, told me his conviction 'that Cuvier thought species not real, but that science could not advance without assuming that they were so.'" ~ ~ ~ ~ ~ "When I came to the conclusion that after all Lamarck was going to be shown to be right, that we must 'go the whole orang,' I re-read his book, and remembering when it was written, I felt I had done him injustice. "Even as to man's gradual acquisition of more and more ideas, and then of speech slowly as the ideas multiplied, and then his persecution of the beings most nearly allied and competing with him--all this is very Darwinian. "The substitution of the variety-making power for 'volition,' 'muscular action,' etc. (and in plants even volition was not called in), is in some respects only a change of names. Call a new variety a new creation, one may say of the former, as of the latter, what you say when you observe that the creationist explains nothing, and only affirms 'it is so because it is so.' "Lamarck's belief in the slow changes in the organic and inorganic world in the year 1800 was surely above the standard of his times, and he was right about progression in the main, though you have vastly advanced that doctrine. As to Owen in his 'Aye Aye' paper, he seems to me a disciple of Pouchet, who converted him at Rouen to 'spontaneous generation.' "Have I not, at p. 412, put the vast distinction between you and Lamarck as to 'necessary progression' strongly enough?" (To Darwin, March 15, 1863. _Lyell's Letters_, ii., p. 365.) Darwin, in the freedom of private correspondence, paid scant respect to the views of his renowned predecessor, as the following extracts from his published letters will show: "Heaven forfend me from Lamarck nonsense of a 'tendency to progression,' 'adaptations from the slow willing of animals,' etc. But the conclusions I am led to are not widely different from his; though the means of change are wholly so." (Darwin's _Life and Letters_, ii., p. 23, 1844.) ~ ~ ~ ~ ~ "With respect to books on this subject, I do not know of any systematical ones, except Lamarck's, which is veritable rubbish.... Is it not strange that the author of such a book as the _Animaux sans Vertèbres_ should have written that insects, which never see their eggs, should _will_ (and plants, their seeds) to be of particular forms, so as to become attached to particular objects."[57] (ii., p. 29, 1844.) ~ ~ ~ ~ ~ "Lamarck is the only exception, that I can think of, of an accurate describer of species, at least in the Invertebrate Kingdom, who has disbelieved in permanent species, but he in his absurd though clever work has done the subject harm." (ii., p. 39, no date.) ~ ~ ~ ~ ~ "To talk of climate or Lamarckian habit producing such adaptions to other organic beings is futile." (ii., p. 121, 1858.) On the other hand, another great English thinker and naturalist of rare breadth and catholicity, and despite the fact that he rejected Lamarck's peculiar evolutional views, associated him with the most eminent biologists. In a letter to Romanes, dated in 1882, Huxley thus estimates Lamarck's position in the scientific world: "I am not likely to take a low view of Darwin's position in the history of science, but I am disposed to think that Buffon and Lamarck would run him hard in both genius and fertility. In breadth of view and in extent of knowledge these two men were giants, though we are apt to forget their services. Von Bär was another man of the same stamp; Cuvier, in a somewhat lower rank, another; and J. Müller another." (_Life and Letters of Thomas Henry Huxley_, ii., p. 42, 1900.) The memory of Lamarck is deeply and warmly cherished throughout France. He gave his country a second Linné. One of the leading botanists in Europe, and the greatest zoölogist of his time, he now shares equally with Geoffroy St. Hilaire and with Cuvier the distinction of raising biological science to that eminence in the first third of the nineteenth century which placed France, as the mother of biologists, in the van of all the nations. When we add to his triumphs in pure zoölogy the fact that he was in his time the philosopher of biology, it is not going too far to crown him as one of the intellectual glories, not only of France, but of the civilized world. How warmly his memory is now cherished may be appreciated by the perusal of the following letter, with its delightful reminiscences, for which we are indebted to the venerable and distinguished zoölogist and comparative anatomist who formerly occupied the chair made illustrious by Lamarck, and by his successor, De Blainville, and who founded the Laboratoire Arago on the Mediterranean, also that of Experimental Zoölogy at Roscoff, and who still conducts the _Journal de Zoologie Expérimentale_. PARIS LE 28 _Décembre_, 1899. M. le PROFESSEUR PACKARD. _Cher Monsieur_: Vous m'avez fait l'honneur de me demander des renseignements sur la famille de De Lamarck, et sur ses relations, afin de vous en servir dans la biographie que vous préparez de notre grand naturaliste. Je n'ai rien appris de plus que ce que vous voulez bien me rappeler comme l'ayant trouvé dans mon adresse de 1889. Je ne connais plus ni les noms ni les adresses des parents de De Lamarck, et c'est avec regret qu'il ne m'est pas possible de répondre à vos désirs. Lorsque je commençai mes études à Paris, on ne s'occupait guère des idées générales de De Lamarck que pour s'en moquer. Excepté Geoffroy St. Hilaire et De Blainville, dont j'ai pu suivre les belles leçons et qui le citaient souvent, on parlait peu de la philosophie zoologique. Il m'a été possible de causer avec des anciens collègues du grand naturaliste; au Jardin des Plantes de très grands savants, dont je ne veux pas écrire le nom, le traitaient _de fou_! Il avait loué un appartement sur le haut d'une maison, et là cherchait d'après la direction des nuages à prévoir l'état du temps. On riait de ces études. N'est-ce pas comme un observatoire de météorologie que ce savant zoologiste avait pour ainsi dire fondé avant que la science ne se fut emparée de l'idée? Lorsque j'eus l'honneur d'être nommé professeur au Jardin des Plantes en 1865, je fis l'historique de la chaire que j'occupais, et qui avait été illustrée par De Lamarck et De Blainville. Je crois que je suis le premier à avoir fait l'histoire de notre grand naturaliste dans un cours public. Je dus travailler pas mal pour arriver à bien saisir l'idée fondamentale de la philosophie. Les définitions de la nature et des forces qui président aux changements qui modifient les êtres d'après les conditions auxquelles ils sont soumis ne sont pas toujours faciles à rendre claires pour un public souvent difficile. Ce qui frappe surtout dans ses raisonnements, c'est que De Lamarck est parfaitement logique. Il comprend très bien ce que plus d'un transformiste de nos jours ne cherche pas à éclairer, que le premier pas, le pas difficile à faire pour arriver à expliquer la création par des modifications successives, c'est le passage de la matière inorganique à la matière organisée, et il imagine la chaleur et l'électricité comme étant les deux facteurs qui par attraction ou répulsion finissent par former ces petits amas organisés qui seront le point de départ de toutes les transformations de tous les organismes. Voilà le point de départ--la génération spontanée se trouve ainsi expliquée! De Lamarck était un grand et profond observateur. On me disait au Museum (des contemporains) qu'il avait l'Instinct de l'Espèce. Il y aurait beaucoup à dire sur cette expression--l'instinct de l'espèce--il m'est difficile dans une simple lettre de développer des idées philosophiques que j'ai sur cette question,--laquelle suppose la notion de l'individu parfaitement définie et acquis. Je ne vous citerai qu'un exemple. Je ne l'ai vu signalé nulle part dans les ouvrages anciens sur De Lamarck. Qu'étaient nos connaissances à l'époque de De Lamarck sur les Polypiers? Les Hydraires étaient loin d'avoir fourni les remarquables observations qui parurent dans le milieu à peu près du siècle qui vient de finir, et cependant De Lamarck déplace hardiment la Lucernaire--l'éloigne des Coralliaires, et la rapproche des êtres qui forment le grand groupe des Hydraires. Ce trait me paraît remarquable et le rapporte à cette réputation qu'il avait au Museum de jouir de l'instinct de l'espèce. De toute part on acclame le grand naturaliste, et'il n'y a pas même une rue portant son nom aux environs du Jardin des Plantes? J'ai eu beau réclamer le conseil municipal de Paris à d'autres favoris que De Lamarck. Lorsque le Jardin des Plantes fut réorganisé par la Convention, De Lamarck avait 50 ans. Il ne s'était jusqu'alors occupé que de botanique. Il fut à cet age chargé de l'histoire de la partie du règne animal renfermant les animaux invertèbres sauf les Insectes et les Crustacés. La chaire est restée la même; elle comprend les vers, les helminthes, les mollusques, et ce qu'on appelait autrefois les Zoophytes ou Rayonnées, enfin les Infusoires. Quelle puissance de travail! Ne fallait-il pas pour passer de la Botanique, à 50 ans, à la Zoologie, et laisser un ouvrage semblable à celui qui illustre encore le nom du Botaniste devenue Zoologiste par ordre de la Convention! Sans doute dans cet ouvrage il y a bien des choses qui ne sont plus acceptables--mais pour le juger avec équité, il faut se porter a l'époque où il fut fait, et alors on est pris d'admiration pour l'auteur d'un aussi immense travail. J'ai une grande admiration pour le génie de De Lamarck, et je ne puis que vous louer de le faire encore mieux connaître de nos contemporains. Recevez, mon cher collègue, l'expression de mes sentiments d'estime pour vos travaux remarquables et croyez-moi--tout à vous, H. DE LACAZE DUTHIERS. FOOTNOTES: [50] For example, while Cuvier's chair was in the field of vertebrate zoölogy, owing to the kindness of Lamarck ("_par gracieuseté de la part de M. de Lamarck_") he had retained that of Mollusca, and yet it was in the special classification of the molluscs that Lamarck did his best work (Blainville, _l. c._, p. 116). [51] De Blainville states that "the Academy did not even allow it to be printed in the form in which it was pronounced" (p. 324); and again he speaks of the lack of judgment in Cuvier's estimate of Lamarck, "the naturalist who had the greatest force in the general conception of beings and of phenomena, although he might often be far from the path" (p. 323). [52] _Fragments Biographiques_, pp. 209-219. [53] _L. c._ p. 81. [54] _Histoire Naturelle Drolatique et Philosophique des Professeurs du Jardin des Plantes, _etc._ Par Isid. S. de Gosse. Avec des Annotations de M. Frédéric Gerard._ Paris, 1847. [55] _Die Naturanschauung von Darwin, Goethe und Lamarck_, Jena, 1882. [56] _Geschichte der Zoologie bis auf Joh. Müller und Charles Darwin_, 1872. [57] We have been unable to find these statements in any of Lamarck's writings. CHAPTER VII LAMARCK'S WORK IN METEOROLOGY AND PHYSICAL SCIENCE When a medical student in Paris, Lamarck, from day to day watching the clouds from his attic windows, became much interested in meteorology, and, indeed, at first this subject had nearly as much attraction for him as botany. For a long period he pursued these studies, and he was the first one to foretell the probabilities of the weather, thus anticipating by over half a century the modern idea of making the science of meteorology of practical use to mankind. His article, "De l'influence de la lune sur l'atmosphère terrestre," appeared in the _Journal de Physique_ for 1798, and was translated in two English journals. The titles of several other essays will be found in the Bibliography at the close of this volume. From 1799 to 1810 he regularly published an annual meteorological report containing the statement of probabilities acquired by a long series of observations on the state of the weather and the variations of the atmosphere at different times of the year, giving indications of the periods when to expect pleasant weather, or rain, storms, tempests, frosts, thaws, etc.; finally the citations of these probabilities of times favorable to fêtes, journeys, voyages, harvesting crops, and other enterprises dependent on good weather. Lamarck thus explained the principles on which he based his probabilities: Two kinds of causes, he says, displace the fluids which compose the atmosphere, some being variable and irregular, others constant, whose action is subject to progressive and fixed laws. Between the tropics constant causes exercise an action so considerable that the irregular effects of variable causes are there in some degree lost; hence result the prevailing winds which in these climates become established and change at determinate epochs. Beyond the tropics, and especially toward the middle of the temperate zones, variable causes predominate. We can, however, still discover there the effects of the action of constant causes, though much weakened; we can assign them the principal epochs, and in a great number of cases make this knowledge turn to our profit. It is in the elevation and depression (_abaissement_) of the moon above and below the celestial equator that we should seek for the most constant of these causes. With his usual facility in such matters, he was not long in advancing a theory, according to which the atmosphere is regarded as resembling the sea, having a surface, waves, and storms; it ought likewise to have a flux and reflux, for the moon ought to exercise the same influence upon it that it does on the ocean. In the temperate and frigid zones, therefore, the wind, which is only the tide of the atmosphere, must depend greatly on the declination of the moon; it ought to blow toward the pole that is nearest to it, and advancing in that direction only, in order to reach every place, traversing dry countries or extensive seas, it ought then to render the sky serene or stormy. If the influence of the moon on the weather is denied, it is only that it may be referred to its phases, but its position in the ecliptic is regarded as affording probabilities much nearer the truth.[58] In each of these annuals Lamarck took great care to avoid making any positive predictions. "No one," he says, "could make these predictions without deceiving himself and abusing the confidence of persons who might place reliance on them." He only intended to propose simple probabilities. After the publication of the first of these annuals, at the request of Lamarck, who had made it the subject of a memoir read to the Institute in 1800 (9 ventôse, l'an IX.), Chaptal, Minister of the Interior, thought it well to establish in France a regular correspondence of meteorological observations made daily at different points remote from each other, and he conferred the direction of it on Lamarck. This system of meteorological reports lasted but a short time, and was not maintained by Chaptal's successor. After three of these annual reports had appeared, Lamarck rather suddenly stopped publishing them, and an incident occurred in connection with their cessation which led to the story that he had suffered ill treatment and neglect from Napoleon I. It has been supposed that Lamarck, who was frank and at times brusque in character, had made some enemies, and that he had been represented to the Emperor as a maker of almanacs and of weather predictions, and that Napoleon, during a reception, showing to Lamarck his great dissatisfaction with the annuals, had ordered him to stop their publication. But according to Bourguin's statement this is not the correct version. He tells us: "According to traditions preserved in the family of Lamarck things did not happen so at all. During a reception given to the Institute at the Tuileries, Napoleon, who really liked Lamarck, spoke to him in a jocular way about his weather probabilities, and Lamarck, very much provoked (_très contrarié_) at being thus chaffed in the presence of his colleagues, resolved to stop the publication of his observations on the weather. What proves that this version is the true one is that Lamarck published another annual which he had in preparation for the year 1810. In the preface he announced that his age, ill health, and his circumstances placed him in the unfortunate necessity of ceasing to busy himself with this periodical work. He ended by inviting those who had the taste for meteorological observations, and the means of devoting their time to it, to take up with confidence an enterprise good in itself, based on a genuine foundation, and from which the public would derive advantageous results." These opuscles, such as they were, in which Lamarck treated different subjects bearing on the winds, great droughts, rainy seasons, tides, etc., became the precursors of the _Annuaires du Bureau des Longitudes_. An observation of Lamarck's on a rare and curious form of cloud has quite recently been referred to by a French meteorologist. It is probable, says M. E. Durand-Greville in _La Nature_, November 24, 1900, that Lamarck was the first to observe the so-called pocky or festoon cloud, or mammato-cirrus cloud, which at rare intervals has been observed since his time.[59] Full of over confidence in the correctness of his views formed without reference to experiments, although Lavoisier, by his discovery of oxygen in the years 1772-85, and other researches, had laid the foundations of the antiphlogistic or modern chemistry, Lamarck quixotically attempted to substitute his own speculative views for those of the discoverers of oxygen--Priestley (1774) and the great French chemist Lavoisier. Lamarck, in his _Hydrogéologie_ (1802), went so far as to declare: "It is not true, and it seems to me even absurd to believe that pure air, which has been justly called _vital air_, and which chemists now call _oxygen gas_, can be the radical of saline matters--namely, can be the principle of acidity, of causticity, or any salinity whatever. There are a thousand ways of refuting this error without the possibility of a reply.... This hypothesis, the best of all those which had been imagined when Lavoisier conceived it, cannot now be longer held, since I have discovered what is really _caloric_" (p. 161). After paying his respects to Priestley, he asks: "What, then, can be the reason why the views of chemists and mine are so opposed?" and complains that the former have avoided all written discussion on this subject. And this after his three physico-chemical works, the _Réfutation_, the _Recherches_, and the _Mémoires_ had appeared, and seemed to chemists to be unworthy of a reply. It must be admitted that Lamarck was on this occasion unduly self-opinionated and stubborn in adhering to such views at a time when the physical sciences were being placed on a firm and lasting basis by experimental philosophers. The two great lessons of science--to suspend one's judgment and to wait for more light in theoretical matters on which scientific men were so divided--and the necessity of adhering to his own line of biological study, where he had facts of his own observing on which to rest his opinions, Lamarck did not seem ever to have learned. The excuse for his rash and quixotic course in respect to his physico-chemical vagaries is that he had great mental activity. Lamarck was a synthetic philosopher. He had been brought up in the encyclopædic period of learning. He had from his early manhood been deeply interested in physical subjects. In middle age he probably lived a very retired life, did not mingle with his compeers or discuss his views with them. So that when he came to publish them, he found not a single supporter. His speculations were received in silence and not deemed worthy of discussion. A very just and discriminating judge of Lamarck's work, Professor Cleland, thus refers to his writings on physics and chemistry: "The most prominent defect in Lamarck must be admitted, quite apart from all consideration of the famous hypothesis which bears his name, to have been want of control in speculation. Doubtless the speculative tendency furnished a powerful incentive to work, but it outran the legitimate deductions from observation, and led him into the production of volumes of worthless chemistry without experimental basis, as well as into spending much time in fruitless meteorological predictions." (_Encyc. Brit._, Art. LAMARCK.) How a modern physicist regards Lamarck's views on physics may be seen by the following statement kindly written for this book by Professor Carl Barus of Brown University, Providence: "Lamarck's physical and chemical speculations, made throughout on the basis of the alchemistic philosophy of the time, will have little further interest to-day than as evidence showing the broadly philosophic tendencies of Lamarck's mind. Made without experiment and without mathematics, the contents of the three volumes will hardly repay perusal, except by the historian interested in certain aspects of pre-Lavoisierian science. The temerity with which physical phenomena are referred to occult static molecules, permeated by subtle fluids, the whole mechanism left without dynamic quality, since the mass of the molecule is to be non-essential, is markedly in contrast with the discredit into which such hypotheses have now fallen. It is true that an explanation of natural phenomena in terms "le feu éthéré, le feu calorique, et le feu fixé" might be interpreted with reference to the modern doctrine of energy; but it is certain that Lamarck, antedating Fresnel, Carnot, Ampère, not to mention their great followers, had not the faintest inkling of the possibility of such an interpretation. Indeed, one may readily account for the resemblance to modern views, seeing that all speculative systems of science must to some extent run in parallel, inasmuch as they begin with the facts of common experience. Nor were his speculations in any degree stimulating to theoretical science. Many of his mechanisms in which the ether operates on a plane of equality with the air can only be regarded with amusement. The whole of his elaborate schemes of color classification may be instanced as forerunners of the methods commercially in vogue to-day; they are not the harbingers of methods scientifically in vogue. One looks in vain for research adequate to carry the load of so much speculative text. "Even if we realize that the beginnings of science could but be made amid such groping in the dark, it is a pity that a man of Lamarck's genius, which seems to have been destitute of the instincts of an experimentalist, should have lavished so much serious thought in evolving a system of chemical physics out of himself." The chemical status of Lamarck's writings is thus stated by Professor H. Carrington Bolton in a letter dated Washington, D. C., February 9, 1900: "Excuse delay in replying to your inquiry as to the chemical status of the French naturalist, Lamarck. Not until this morning have I found it convenient to go to the Library of Congress. That Library has not the _Recherches_ nor the _Mémoires_, but the position of Lamarck is well known. He had no influence on chemistry, and his name is not mentioned in the principal histories of chemistry. He made no experiments, but depended upon his imagination for his facts; he opposed the tenets of the new French school founded by Lavoisier, and proposed a fanciful scheme of abstract principles that remind one of alchemy. "Cuvier, in his _Éloge_ (_Mémoires Acad. Royale des Sciences_, 1832), estimates Lamarck correctly as respects his position in physical science." Lamarck boldly carried the principle of change and evolution into inorganic nature by the same law of change of circumstances producing change of species. Under the head, "De l'espèce parmi les minéraux," p. 149, the author states that he had for a long time supposed that there were no species among minerals. Here, also, he doubts, and boldly, if not rashly, in this case, opposes accepted views, and in this field, as elsewhere, shows, at least, his independence of thought. "They teach in Paris," he says, "that the integrant molecule of each kind of compound is invariable in nature, and consequently that it is as old as nature, hence, mineral species are constant. "For myself, I declare that I am persuaded, and even feel convinced, that the integrant molecule of every compound substance whatever, may change its nature, namely, may undergo changes in the number and in the proportions of the principles which compose it." He enlarges on this subject through eight pages. He was evidently led to take this view from his assumption that everything, every natural object, organic or inorganic, undergoes a change. But it may be objected that this view will not apply to minerals, because those of the archæan rocks do not differ, and have undergone no change since then to the present time, unless we except such minerals as are alteration products due to metamorphism. The primary laws of nature, of physics, and of chemistry are unchangeable, while change, progression from the generalized to the specialized, is distinctly characteristic of the organic as opposed to the inorganic world. FOOTNOTES: [58] "On the Influence of the Moon on the Earth's Atmosphere," _Journal de Physique_, prairial, l'an VI. (1798). [59] Nature, Dec. 6, 1900. CHAPTER VIII LAMARCK'S WORK IN GEOLOGY Whatever may be said of his chemical and physical lucubrations, Lamarck in his geological and palæontological writings is, despite their errors, always suggestive, and in some most important respects in advance of his time. And this largely for the reason that he had once travelled, and to some extent observed geological phenomena, in the central regions of France, in Germany, and Hungary; visiting mines and collecting ores and minerals, besides being in a degree familiar with the French cretaceous fossils, but more especially those of the tertiary strata of Paris and its vicinity. He had, therefore, from his own experience, slight as it was, some solid grounds of facts and observations on which to meditate and from which to reason. He did not attempt to touch upon cosmological theories--chaos and creation--but, rather, confined himself to the earth, and more particularly to the action of the ocean, and to the changes which he believed to be due to organic agencies. The most impressive truth in geology is the conception of the immensity of past time, and this truth Lamarck fully realized. His views are to be found in a little book of 268 pages, entitled _Hydrogéologie_. It appeared in 1802 (an X.), or ten years before the first publication of Cuvier's famous _Discours sur les Revolutions de la Surface du Globe_ (1812). Written in his popular and attractive style, and thoroughly in accord with the cosmological and theological prepossessions of the age, the Discours was widely read, and passed through many editions. On the other hand, the _Hydrogéologie_ died stillborn, with scarcely a friend or a reader, never reaching a second edition, and is now, like most of his works, a bibliographical rarity. The only writer who has said a word in its favor, or contrasted it with the work of Cuvier, is the judicious and candid Huxley, who, though by no means favorable to Lamarck's factors of evolution, frankly said: "The vast authority of Cuvier was employed in support of the traditionally respectable hypotheses of special creation and of catastrophism; and the wild speculations of the _Discours sur les Revolutions de la Surface du Globe_ were held to be models of sound scientific thinking, while the really much more sober and philosophic hypotheses of the _Hydrogéologie_ were scouted."[60] Before summarizing the contents of this book, let us glance at the geological atmosphere--thin and tenuous as it was then--in which Lamarck lived. The credit of being the first observer, before Steno (1669), to state that fossils are the remains of animals which were once alive, is due to an Italian, Frascatero, of Verona, who wrote in 1517. "But," says Lyell,[61] "the clear and philosophical views of Frascatero were disregarded, and the talent and argumentative powers of the learned were doomed for three centuries to be wasted in the discussion of these two simple and preliminary questions: First, whether fossil remains had ever belonged to living creatures; and, secondly, whether, if this be admitted, all the phenomena could not be explained by the deluge of Noah." Previous to this the great artist, architect, engineer, and musician, Leonardo da Vinci (1452-1519), who, among other great works, planned and executed some navigable canals in Northern Italy, and who was an observer of rare penetration and judgment, saw how fossil shells were formed, saying that the mud of rivers had covered and penetrated into the interior of fossil shells at a time when these were still at the bottom of the sea near the coast.[62] That versatile and observing genius, Bernard Palissy, as early as 1580, in a book entitled _The Origin of Springs from Rain-water_, and in other writings, criticized the notions of the time, especially of Italian writers, that petrified shells had all been left by the universal deluge. "It has happened," said Fontenelle, in his eulogy on Palissy, delivered before the French Academy a century and a half later, "that a potter who knew neither Latin nor Greek dared, toward the end of the sixteenth century, to say in Paris, and in the presence of all the doctors, that fossil shells were veritable shells deposited at some time by the sea in the places where they were then found; that the animals had given to the figured stones all their different shapes, and that he boldly defied all the school of Aristotle to attack his proofs."[63] Then succeeded, at the end of the seventeenth century, the forerunners of modern geology: Steno (1669), Leibnitz (1683), Ray (1692), Woodward (1695), Vallisneri (1721), while Moro published his views in 1745. In the eighteenth century Réaumur[64] (1720) presented a paper on the fossil shells of Touraine. Cuvier[65] thus pays his respects, in at least an unsympathetic way, to the geological essayists and compilers of the seventeenth century: "The end of the seventeenth century lived to see the birth of a new science, which took, in its infancy, the high-sounding name of 'Theory of the Earth.' Starting from a small number of facts, badly observed, connecting them by fantastic suppositions, it pretended to go back to the origin of worlds, to, as it were, play with them, and to create their history. Its arbitrary methods, its pompous language, altogether seemed to render it foreign to the other sciences, and, indeed, the professional savants for a long time cast it out of the circle of their studies." Their views, often premature, composed of half-truths, were mingled with glaring errors and fantastic misconceptions, but were none the less germinal. Leibnitz was the first to propose the nebular hypothesis, which was more fully elaborated by Kant and Laplace. Buffon, influenced by the writing of Leibnitz, in his _Théorie de la Terre_, published in 1749, adopted his notion of an original volcanic nucleus and a universal ocean, the latter as he thought leaving the land dry by draining into subterranean caverns. He also dimly saw, or gathered from his reading, that the mountains and valleys were due to secondary causes; that fossiliferous strata had been deposited by ocean currents, and that rivers had transported materials from the highlands to the lowlands. He also states that many of the fossil shells which occur in Europe do not live in the adjacent seas, and that there are remains of fishes and of plants not now living in Europe, and which are either extinct or live in more southern climates, and others in tropical seas. Also that the bones and teeth of elephants and of the rhinoceros and hippopotamus found in Siberia and elsewhere in northern Europe and Asia indicate that these animals must have lived there, though at present restricted to the tropics. In his last essay, _Époques de la Nature_ (1778), he claims that the earth's history may be divided into epochs, from the earliest to the present time. The first epoch was that of fluidity, of incandescence, when the earth and the planets assumed their form; the second, of cooling; the third, when the waters covered the earth, and volcanoes began to be active; the fourth, that of the retreat of the seas, and the fifth the age when the elephants, the hippopotamus, and other southern animals lived in the regions of the north; the sixth, when the two continents, America and the old world, became separate; the seventh and last being the age of man. Above all, by his attractive style and bold suggestions he popularized the subjects and created an interest in these matters and a spirit of inquiry which spread throughout France and the rest of Europe. But notwithstanding the crude and uncritical nature of the writings of the second half of the eighteenth century, resulting from the lack of that more careful and detailed observation which characterizes our day, there was during this period a widespread interest in physical and natural science, and it led up to that more exact study of nature which signalizes the nineteenth century. "More new truths concerning the external world," says Buckle, "were discovered in France during the latter half of the eighteenth century than during all preceding periods put together."[66] As Perkins[67] says: "Interest in scientific study, as in political investigation, seemed to rise suddenly from almost complete inactivity to extraordinary development. In both departments English thinkers had led the way, but if the impulse to such investigations came from without, the work done in France in every branch of scientific research during the eighteenth century was excelled by no other nation, and England alone could assert any claim to results of equal importance. The researches of Coulomb in electricity, of Buffon in geology, of Lavoisier in chemistry, of Daubenton in comparative anatomy, carried still farther by their illustrious successors towards the close of the century, did much to establish conceptions of the universe and its laws upon a scientific basis." And not only did Rousseau make botany fashionable, but Goldsmith wrote from Paris in 1755: "I have seen as bright a circle of beauty at the chemical lectures of Rouelle as gracing the court of Versailles." Petit lectured on astronomy to crowded houses, and among his listeners were gentlemen and ladies of fashion, as well as professional students.[68] The popularizers of science during this period were Voltaire, Montesquieu, Alembert, Diderot, and other encyclopædists. Here should be mentioned one of Buffon's contemporaries and countrymen; one who was the first true field geologist, an observer rather than a compiler or theorist. This was Jean E. Guettard (1715-1786). He published, says Sir Archibald Geikie, in his valuable work, _The Founders of Geology_, about two hundred papers on a wide range of scientific subjects, besides half a dozen quarto volumes of his observations, together with many excellent plates. Geikie also states that he is undoubtedly entitled to rank among the first great pioneers of modern geology. He was the first (1751) to make a geological map of northern France, and roughly traced the limits of his three bands or formations from France across the southeastern English counties. In his work on "The degradation of mountains effected in our time by heavy rains, rivers, and the sea,"[69] he states that the sea is the most potent destroyer of the land, and that the material thus removed is deposited either on the land or along the shores of the sea. He thought that the levels of the valleys are at present being raised, owing to the deposit of detritus in them. He points out that the deposits laid down by the ocean do not extend far out to sea, "that consequently the elevations of new mountains in the sea, by the deposition of sediment, is a process very difficult to conceive; that the transport of the sediment as far as the equator is not less improbable; and that still more difficult to accept is the suggestion that the sediment from our continent is carried into the seas of the New World. In short, we are still very little advanced towards the theory of the earth as it now exists." Guettard was the first to discover the volcanoes of Auvergne, but he was "hopelessly wrong" in regard to the origin of basalt, forestalling Werner in his mistakes as to its aqueous origin. He was thus the first Neptunist, while, as Geikie states, his "observations in Auvergne practically started the Vulcanist camp." We now come to Lamarck's own time. He must have been familiar with the results of Pallas's travels in Russia and Siberia (1793-94). The distinguished German zoölogist and geologist, besides working out the geology of the Ural Mountains, showed, in 1777, that there was a general law in the formation of all mountain chains composed chiefly of primary rocks;[70] the granitic axis being flanked by schists, and these by fossiliferous strata. From his observations made on the Volga and about its mouth, he presented proofs of the former extension, in comparatively recent times, of the Caspian Sea. But still more pregnant and remarkable was his discovery of an entire rhinoceros, with its flesh and skin, in the frozen soil of Siberia. His memoir on this animal places him among the forerunners of, if not within the ranks of, the founders of palæontology. Meanwhile Soldani, an Italian, had, in 1780, shown that the limestone strata of Italy had accumulated in a deep sea, at least far from land, and he was the first to observe the alternation of marine and fresh-water strata in the Paris basin. Lamarck must have taken much interest in the famous controversy between the Vulcanists and Neptunists. He visited Freyburg in 1771; whether he met Werner is not known, as Werner began to lecture in 1775. He must have personally known Faujas of Paris, who, in 1779, published his description of the volcanoes of Vivarais and Velay; while Desmarest's (1725-1815) elaborate work on the volcanoes of Auvergne, published in 1774, in which he proved the igneous origin of basalt, was the best piece of geological exploration which had yet been accomplished, and is still a classic.[71] Werner (1750-1817), the propounder of the Neptunian theory, was one of the founders of modern geology and of palæontology. His work entitled _Ueber die aüssern Kennzeichen der Fossilien_ appeared in 1774; his _Kurze Klassifikation und Beschreibung der Gebirgsarten_ in 1787. He discovered the law of the superposition of stratified rocks, though he wrongly considered volcanic rocks, such as basalt, to be of aqueous origin, being as he supposed formed of chemical precipitates from water. But he was the first to state that the age of different formations can be told by their fossils, certain species being confined to particular beds, while others ranged throughout whole formations, and others seemed to occur in several different formations; "the original species found in these formations appearing to have been so constituted as to live through a variety of changes which had destroyed hundreds of other species which we find confined to particular beds."[72] His views as regards fossils, as Jameson states, were probably not known to Cuvier, and it is more than doubtful whether Lamarck knew of them. He observed that fossils appear first in "transition" or palæozoic strata, and were mainly corals and molluscs; that in the older carboniferous rocks the fossils are of higher types, such as fish and amphibious animals; while in the tertiary or alluvial strata occur the remains of birds and quadrupeds. He thought that marine plants were more ancient than land plants. His studies led him to infer that the fossils contained in the oldest rocks are very different from any of the species of the present time; that the newer the formation, the more do the remains approach in form to the organic beings of the present creation, and that in the very latest formations, fossil remains of species now existing occur. Such advanced views as these would seem to entitle Werner to rank as one of the founders of palæontology.[73] Hutton's _Theory of the Earth_ appeared in 1785, and in a more developed state, as a separate work, in 1795.[74] "The ruins of an older world," he said, "are visible in the present structure of our planet, and the strata which now compose our continents have been once beneath the sea, and were formed out of the waste of preëxisting continents. The same forces are still destroying, by chemical decomposition or mechanical violence, even the hardest rocks, and transporting the materials to the sea, where they are spread out and form strata analogous to those of more ancient date. Although loosely deposited along the bottom of the ocean, they became afterwards altered and consolidated by volcanic heat, and were then heaved up, fractured, and contorted." Again he said: "In the economy of the world I can find no traces of a beginning, no prospect of an end." As Lyell remarks: "Hutton imagined that the continents were first gradually destroyed by aqueous degradation, and when their ruins had furnished materials for new continents, they were upheaved by violent convulsions. He therefore required alternate periods of general disturbance and repose." To Hutton, therefore, we are indebted for the idea of the immensity of the duration of time. He was the forerunner of Lyell and of the uniformitarian school of geologists. Hutton observed that fossils characterized certain strata, but the value of fossils as time-marks and the principle of the superposition of stratified fossiliferous rocks were still more clearly established by William Smith, an English surveyor, in 1790. Meanwhile the Abbé Haüy, the founder of crystallography, was in 1802 Professor of Mineralogy in the Jardin des Plantes. _Lamarck's Contributions to Physical Geology; his Theory of the Earth._ Such were the amount and kind of knowledge regarding the origin and structure of our earth which existed at the close of the eighteenth century, while Lamarck was meditating his _Hydrogéologie_, and had begun to study the invertebrate fossils of the Paris tertiary basin. His object, he says in his work, is to present certain considerations which he believed to be new and of the first order, which had escaped the notice of physicists, and which seemed to him should serve as the foundations for a good theory of the earth. His theses are: 1. What are the natural consequences of the influence and the movements of the waters on the surface of the globe? 2. Why does the sea constantly occupy a basin within the limits which contain it, and there separate the dry parts of the surface of the globe always projecting above it? 3. Has the ocean basin always existed where we actually see it, and if we find proofs of the sojourn of the sea in places where it no longer remains, by what cause was it found there, and why is it no longer there? 4. What influence have living bodies exerted on the substances found on the surface of the earth and which compose the crust which invests it, and what are the general results of this influence? Lamarck then disclaims any intentions of framing brilliant hypotheses based on supposititious principles, but nevertheless, as we shall see, he falls into this same error, and like others of his period makes some preposterous hypotheses, though these are far less so than those of Cuvier's _Discours_. He distinguishes between the action of rivers or of fresh-water currents, torrents, storms, the melting of snow, and the work of the ocean. The rivers wear away and bear materials from the highlands to the lowlands, so that the plains are gradually elevated; ravines form and become immense valleys, and their sides form elevated crests and pass into mountain ranges. He brings out and emphasizes the fact, now so well known, that the erosive action of rain and rivers has formed mountains of a certain class. "It is then evident to me, that every mountain which is not the result of a _volcanic irruption_ or of some local catastrophe, has been carved out from a plain, where its mass is gradually formed, and was a part of it; hence what in this case are the summits of the mountains are only the remains of the former level of the plain unless the process of washing away and other means of degradation have not since reduced its height." Now this will apply perfectly well to our table-lands, mesas, the mountains of our bad-lands, even to our Catskills and to many elevations of this nature in France and in northern Africa. But Lamarck unfortunately does not stop here, but with the zeal of an innovator, by no means confined to his time alone, claims that the mountain masses of the Alps and the Andes were carved out of plains which had been raised above the sea-level to the present heights of those mountains. Two causes, he says, have concurred in forming these elevated plains. "One consists in the continual accumulation of material filling the portion of the ocean-basin from which the same seas slowly retreat; for it does not abandon those parts of the ocean-basin which are situated nearer and nearer to the shores that it tends to leave, until after having filled its bottom and having gradually raised it. It follows that the coasts which the sea is abandoning are never made by a very deep-lying formation, however often it appears to be such, for they are continually elevated as the result of the perpetual balancing of the sea, which casts off from its shores all the sediments brought down by the rivers; in such a way that the great depths of the ocean are not near the shore from which the sea retreats, but out in the middle of the ocean and near the opposite shores which the sea tends to invade. "The other cause, as we shall see, is found in the detritus of organic bodies successively accumulated, which perpetually elevates, although with extreme slowness, the soil of the dry portions of the globe, and which does it all the more rapidly, as the situation of these parts gives less play to the degradation of the surface caused by the rivers. "Doubtless a plain which is destined some day to furnish the mountains which the rivers will carve out from its mass would have, when still but a little way from the sea, but a moderate elevation above its river channels; but gradually as the ocean basin removed from this plain, this basin constantly sinking down into the interior (_épaisseur_) of the external crust of the globe, and the soil of the plain perpetually rising higher from the deposition of the detritus of organic bodies, it results that, after ages of elevation of the plain in question, it would be in the end sufficiently thick for high mountains to be shaped and carved out of its mass. "Although the ephemeral length of life of man prevents his appreciation of this fact, it is certain that the soil of a plain unceasingly acquires a real increase in its elevation in proportion as it is covered with different plants and animals. Indeed the débris successively heaped up for numerous generations of all these beings which have by turns perished, and which, as the result of the action of their organs, have, during the course of this life, given rise to combinations which would never have existed without this means, most of the principles which have formed them not being borrowed from the soil; this débris, I say, wasting successively on the soil of the plain in question, gradually increases the thickness of its external bed, multiplies there the mineral matters of all kinds and gradually elevates the formation." Our author, as is evident, had no conception, nor had any one else at the time he wrote, of the slow secular elevation of a continental plateau by crust-movements, and Lamarck's idea of the formation of elevated plains on land by the accumulation of débris of organisms is manifestly inadequate, our aërial or eolian rocks and loess being wind-deposits of sand and silt rather than matters of organic origin. Thus he cites as an example of his theory the vast elevated plains of Tartary, which he thought had been dry land from time immemorable, though we now know that the rise took place in the quaternary or present period. On the other hand, given these vast elevated plains, he was correct in affirming that rivers flowing through them wore out enormous valleys and carved out high mountains, left standing by atmospheric erosion, for examples of such are to be seen in the valley of the Nile, the Colorado, the Upper Missouri, etc. He then distinguishes between granitic or crystalline mountains, and those composed of stratified rocks and volcanic mountains. The erosive action of rivers is thus discussed; they tend first, he says, to fill up the ocean basins, and second, to make the surface of the land broken and mountainous, by excavating and furrowing the plains. Our author did not at all understand the causes of the inclination or tilting up of strata. Little close observation or field work had yet been done, and the rocks about Paris are but slightly if at all disturbed. He attributes the dipping down of strata to the inclination of the shores of the sea, though he adds that nevertheless it is often due to local subsidences. And then he remarks that "indeed in many mountains, and especially in the Pyrenees, in the very centre of these mountains, we observe that the strata are for the most part either vertical or so inclined that they more or less approach this direction." "But," he asks, "should we conclude from this that there has necessarily occurred a universal catastrophe, a general overturning? This assumption, so convenient for those naturalists who would explain all the facts of this kind without taking the trouble to observe and study the course which nature follows, is not at all necessary here; for it is easy to conceive that the inclined direction of the beds in the mountains may have been produced by other causes, and especially by causes more natural and less hypothetical than a general overturning of strata." While streams of fresh water tend to fill up and destroy the ocean basins, he also insists that the movements of the sea, such as the tides, currents, storms, submarine volcanoes, etc., on the contrary, tend to unceasingly excavate and reëstablish these basins. Of course we now know that tides and currents have no effect in the ocean depths, though their scouring effects near shore in shallow waters have locally had a marked effect in changing the relations of land and sea. Lamarck went so far as to insist that the ocean basin owes its existence and its preservation to the scouring action of the tides and currents. The earth's interior was, in Lamarck's opinion, solid, formed of quartzose and silicious rocks, and its centre of gravity did not coincide with its geographical centre, or what he calls the _centre de forme_. He imagined also that the ocean revolved around the globe from east to west, and that this movement, by its continuity, displaced the ocean basin and made it pass successively over all the surface of the earth. Then, in the third chapter, he asks if the basin of the sea has always been where we now actually see it, and whether we find proofs of the sojourn of the sea in the place where it is now absent; if so, what are the causes of these changes. He reiterates his strange idea of a general movement of the ocean from east to west, at the rate of at least three leagues in twenty-four hours and due to the moon's influence. And here Lamarck, in spite of his uniformitarian principles, is strongly cataclysmic. What he seems to have in mind is the great equatorial current between Africa and the West Indies. To this perpetual movement of the waters of the Atlantic Ocean he ventures to attribute the excavation of the Gulf of Mexico, and presumes that at the end of ages it will break through the Isthmus of Panama, and transform America into two great islands or two small continents. Not understanding that the islands are either the result of upheaval, or outliers of continents, due to subsidence, Lamarck supposed that his westward flow of the ocean, due to the moon's attraction, eroded the eastern shores of America, and the currents thus formed "in their efforts to move westward, arrested by America and by the eastern coasts of China, were in great part diverted towards the South Pole, and seeking to break through a passage across the ancient continent have, a long time since, reduced the portion of this continent which united New Holland to Asia into an archipelago which comprises the Molucca, Philippine, and Mariana Islands." The West Indies and Windward Islands were formed by the same means, and the sea not breaking through the Isthmus of Panama was turned southward, and the action of its currents resulted in detaching the island of Tierra del Fuego from South America. In like manner New Zealand was separated from New Holland, Madagascar from Africa, and Ceylon from India. He then refers to other "displacements of the ocean basin," to the shallowing of the Straits of Sunda, of the Baltic Sea, the ancient subsidence of the coast of Holland and Zealand, and states that Sweden offers all the appearance of having recently emerged from the sea, while the Caspian Sea, formerly much larger than at present, was once in communication with the Black Sea, and that some day the Straits of Sunda and the Straits of Dover will be dry land, so that the union of England and France will be formed anew. Strangely enough, with these facts known to him, Lamarck did not see that such changes were due to changes of level of the land rather than to their being abandoned or invaded by the sea, but explained these by his bizarre hypothesis of westward-flowing currents due to the moon's action; though it should be in all fairness stated that down to recent times there have been those who believed that it is the sea and not the land which has changed its level. This idea, that the sea and not the land has changed its level, was generally held at the time Lamarck wrote, though Strabo had made the shrewd observation that it was the land which moved. The Greek geographer threw aside the notion of some of his contemporaries, and with wonderful prevision, considering the time he wrote and the limited observations he could make, claimed that it is not the sea which has risen or fallen, but the land itself which is sometimes raised up and sometimes depressed, while the sea-bottom may also be elevated or sunk down. He refers to such facts as deluges, earthquakes, and volcanic eruptions, and sudden swellings of the land beneath the sea. "And it is not merely the small, but the large islands also, not merely the islands, but the continents which can be lifted up together with the sea; and, too, the large and small tracts may subside, for habitations and cities, like Bure, Bizona, and many others, have been engulfed by earthquakes."[75] But it was not until eighteen centuries later that this doctrine, under the teachings of Playfair, Leopold von Buch, and Élie de Beaumont (1829-30) became generally accepted. In 1845 Humboldt remarked, "It is a fact to-day recognized by all geologists, that the rise of continents is due to an actual upheaval, and not to an apparent subsidence occasioned by a general depression of the level of the sea" (_Cosmos_, i). Yet as late as 1869 we have an essay by H. Trautschold[76] in which is a statement of the arguments which can be brought forward in favor of the doctrine that the increase of the land above sea level is due to the retirement of the sea.[77] As authentic and unimpeachable proofs of the former existence of the sea where now it is absent, Lamarck cites the occurrence of fossils in rocks inland. Lamarck's first paper on fossils was read to the Institute in 1799, or about three years previous to the publication of the _Hydrogéologie_. He restricts the term "fossils" to vegetable and animal remains, since the word in his time was by some loosely applied to minerals as well as fossils; to anything dug out of the earth. "We find fossils," he says, "on dry land, even in the middle of continents and large islands; and not only in places far removed from the sea, but even on mountains and in their bowels, at considerable heights, each part of the earth's surface having at some time been a veritable ocean bottom." He then quotes at length accounts of such instances from Buffon, and notices their prodigious number, and that while the greater number are marine, others are fresh-water and terrestrial shells, and the marine shells may be divided into littoral and pelagic. "This distinction is very important to make, because the consideration of fossils is, as we have already said, one of the principal means of knowing well the revolutions which have taken place on the surface of our globe. This subject is of great importance, and under this point of view it should lead naturalists to study fossil shells, in order to compare them with their analogues which we can discover in the sea; finally, to carefully seek the places where each species lives, the banks which are formed of them, the different beds which these banks may present, etc., etc., so that we do not believe it out of place to insert here the principal considerations which have already resulted from that which is known in this respect. "_The fossils which are found in the dry parts of the surface of the globe are evident indications of a long sojourn of the sea in the very places where we observe them._" Under this heading, after repeating the statement previously made that fossils occur in all parts of the dry land, in the midst of the continents and on high mountains, he inquires _by what cause_ so many marine shells could be found in the explored parts of the world. Discarding the old idea that they are monuments of the deluge, transformed into fossils, he denies that there was such a general catastrophe as a universal deluge, and goes on to say in his assured, but calm and philosophic way: "On the globe which we inhabit, everything is submitted to continual and inevitable changes, which result from the essential order of things: they take place, in truth, with more or less promptitude or slowness, according to the nature, the condition, or the situation of the objects; nevertheless they are wrought in some time or other. "To nature, time is nothing, and it never presents a difficulty; she always has it at her disposal, and it is for her a means without limit, with which she has made the greatest as well as the least things. "The changes to which everything in this world is subjected are changes not only of form and of nature, but they are changes also of bulk, and even of situation. "All the considerations stated in the preceding chapters should convince us that nothing on the surface of the terrestrial globe is immutable. They teach us that the vast ocean which occupies so great a part of the surface of our globe cannot have its bed constantly fixed in the same place; that the dry or exposed parts of this surface themselves undergo perpetual changes in their condition, and that they are in turn successively invaded and abandoned by the sea. "There is, indeed, every evidence that these enormous masses of water continually displace themselves, both their bed and their limits. "In truth these displacements, which are never interrupted, are in general only made with extreme and almost inappreciable slowness, but they are in ceaseless operation, and with such constancy that the ocean bottom, which necessarily loses on one side while it gains on another, has already, without doubt, spread over not only once, but even several times, every point of the surface of the globe. "If it is thus, if each point of the surface of the terrestrial globe has been in turn dominated by the seas--that is to say, has contributed to form the bed of those immense masses of water which constitute the ocean--it should result (1) that the insensible but uninterrupted transfer of the bed of the ocean over the whole surface of the globe has given place to deposits of the remains of marine animals which we should find in a fossil state; (2) that this translation of the ocean basin should be the reason why the dry portions of the earth are always more elevated than the level of the sea; so that the old ocean bed should become exposed without being elevated above the sea, and without consequently giving rise to the formation of mountains which we observe in so many different regions of the naked parts of our globe." Thus littoral shells of many genera, such as Pectens, Tellinæ, cockle shells, turban shells (_sabots_), etc., madrepores and other littoral polyps, the bones of marine or of amphibious animals which have lived near the sea, and which occur as fossils, are then unimpeachable monuments of the sojourn of the sea on the points of the dry parts of the globe where we observe their deposits, and besides these occur deep-water forms. "Thus the encrinites, the belemnites, the orthoceratites, the ostracites, the terebratules, etc., all animals which habitually live at the bottom, found for the most part among the fossils deposited on the point of the globe in question, are unimpeachable witnesses which attest that this same place was once part of the bottom or great depths of the sea." He then attempts to prove, and does so satisfactorily, that the shells he refers to are what he calls deep-water (pélagiennes). He proves the truth of his thesis by the following facts: 1. We are already familiar with a marine Gryphæa, and different Terebratulæ, also marine shell-fish, which do not, however, live near shore. 2. Also the greatest depth which has been reached with the rake or the dredge is not destitute of molluscs, since we find there a great number which only live at this depth, and without instruments to reach and bring them up we should know nothing of the _cones_, _olives_, Mitra, many species of Murex, Strombus, etc. 3. Finally, since the discovery of a living Encrinus, drawn up on a sounding line from a great depth, and where lives the animal or polyp in question, it is not only possible to assure ourselves that at this depth there are other living animals, but on the contrary we are strongly bound to think that other species of the same genus, and probably other animals of different genera, also live at the same depths. All this leads one to admit, with Bruguière,[78] the existence of deep-water shell-fish and polyps, which, like him, I distinguish from littoral shells and polyps. "The two sorts of monuments of which I have above spoken, namely, littoral and deep-sea fossils, may be, and often should be, found separated by different beds in the same bank or in the same mountains, since they have been deposited there at very different epochs. But they may often be found mixed together, because the movements of the water, the currents, submarine volcanoes, etc., have overturned the beds, yet some regular deposits in water always tranquil would be left in quite distant beds.... Every dry part of the earth's surface, when the presence or the abundance of marine fossils prove that formerly the sea has remained in that place, has necessarily twice received, for a single incursion of the sea, littoral shells, and once deep-sea shells, in three different deposits--this will not be disputed. But as such an incursion of the sea can only be accomplished by a period of immense duration, it follows that the littoral shells deposited at the first sojourn of the edge of the sea, and constituting the first deposit, have been destroyed--that is to say, have not been preserved to the present time; while the deep-water shells form the second deposit, and there the littoral shells of the third deposit are, in fact, the only ones which now exist, and which constitute the fossils that we see." He again asserts that these deposits could not be the result of any sudden catastrophe, because of the necessarily long sojourn of the sea to account for the extensive beds of fossil shells, the remains of "infinitely multiplied generations of shelled animals which have lived in this place, and have there successively deposited their débris." He therefore supposes that these remains, "continually heaped up, have formed these shell banks, become fossilized after the lapse of considerable time, and in which it is often possible to distinguish different beds." He then continues his line of anti-catastrophic reasoning, and we must remember that in his time facts in biology and geology were feebly grasped, and scientific reasoning or induction was in its infancy. "I would again inquire how, in the supposition of a universal catastrophe, there could have been preserved an infinity of delicate shells which the least shock would break, but of which we now find a great number uninjured among other fossils. How also could it happen that bivalve shells, with which calcareous rocks and even those changed into a silicious condition are interlarded, should be all still provided with their two valves, as I have stated, if the animals of these shells had not lived in these places? "There is no doubt but that the remains of so many molluscs, that so many shells deposited and consequently changed into fossils, and most of which were totally destroyed before their substance became silicified, furnished a great part of the calcareous matter which we observe on the surface and in the upper beds of the earth. "Nevertheless there is in the sea, for the formation of calcareous matter, a cause which is greater than shelled molluscs, which is consequently still more powerful, and to which must be referred ninety-nine hundredths, and indeed more, of the calcareous matter occurring in nature. This cause, so important to consider, is the existence of _coralligenous polyps_, which we might therefore call _testaceous polyps_, because, like the testaceous molluscs, these polyps have the faculty of forming, by a transudation or a continual secretion of their bodies, the stony and calcareous polypidom on which they live. "In truth these polyps are animals so small that a single one only forms a minute quantity of calcareous matter. But in this case what nature does not obtain in any volume or in quantity from any one individual, she simply receives by the number of animals in question, through the enormous multiplicity of these animals, and their astonishing fecundity--namely, by the wonderful faculty they have of promptly regenerating, of multiplying in a short time their generations successively, and rapidly accumulating; finally, by the total amount of reunion of the products of these numerous little animals. "Moreover, it is a fact now well known and well established that the coralligenous polyps, namely, this great family of animals with coral stocks, such as the millepores, the madrepores, astrææ, meandrinæ, etc., prepare on a great scale at the bottom of the sea, by a continual secretion of their bodies, and as the result of their enormous multiplication and their accumulated generations, the greatest part of the calcareous matter which exists. The numerous coral stocks which these animals produce, and whose bulk and numbers perpetually increase, form in certain places islands of considerable extent, fill up extensive bays, gulfs, and roadsteads; in a word, close harbors, and entirely change the condition of coasts. "These enormous banks of madrepores and millepores, heaped upon each other, covered and intermingled with serpulæ, different kinds of oysters, patellæ, barnacles, and other shells fixed by their base, form irregular mountains of an almost limitless extent. "But when, after the lapse of considerable time, the sea has left the places where these immense deposits are laid down, then the slow but combined alteration that these great masses undergo, left uncovered and exposed to the incessant action of the air, light, and a variable humidity, changes them gradually into fossils and destroys their membranous or gelatinous part, which is the readiest to decompose. This alteration, which the enormous masses of the corals in question continued to undergo, caused their structure to gradually disappear, and their great porosity unceasingly diminished the parts of these stony masses by displacing and again bringing together the molecules composing them, so that, undergoing a new aggregation, these calcareous molecules obtained a number of points of contact, and constituted harder and more compact masses. It finally results that instead of the original masses of madrepores and millepores there occurs only masses of a compact calcareous rock, which modern mineralogists have improperly called _primitive limestone_, because, seeing in it no traces of shells or corals, they have mistaken these stony masses for deposits of a matter primitively existing in nature." He then reiterates the view that these deposits of marble and limestones, often forming mountain ranges, could not have been the result of a universal catastrophe, and in a very modern way goes on to specify what the limits of catastrophism are. The only catastrophes which a naturalist can reasonably admit as having taken place are partial or local ones, those dependent on causes acting in isolated places, such as the disturbances which are caused by volcanic eruptions, by earthquakes, by local inundations, by violent storms, etc. These catastrophes are with reason admissible, because we observe their analogues, and because we know that they often happen. He then gives examples of localities along the coast of France, as at Manche, where there are ranges of high hills made up of limestones containing Gryphææ, ammonites, and other deep-water shells. In the conclusion of the chapter, after stating that the ocean has repeatedly covered the greater part of the earth, he then claims that "the displacement of the sea, producing a constantly variable inequality in the mass of the terrestrial radii, has necessarily caused the earth's centre of gravity to vary, as also its two poles.[79] Moreover, since it appears that this variation, very irregular as it is, not being subjected to any limits, it is very probable that each point of the surface of the planet we inhabit is really in the case of successively finding itself subjected to different climates." He then exclaims in eloquent, profound, and impassioned language: "How curious it is to see that such suppositions receive their confirmation from the consideration of the state of the earth's surface and of its external crust, from that of the nature of certain fossils found in abundance in the northern regions of the earth, and whose analogues now live in warm climates; finally, in that of the ancient astronomical observations of the Egyptians. "Oh, how great is the antiquity of the terrestrial globe, and how small are the ideas of those who attribute to the existence of this globe a duration of six thousand and some hundred years since its origin down to our time! "The physico-naturalist and the geologist in this respect see things very differently; for if they have given the matter the slightest consideration--the one, the nature of fossils spread in such great numbers in all the exposed parts of the globe, both in elevated situations and at considerable depths in the earth; the other, the number and disposition of the beds, as also the nature and order of the materials which compose the external crust of this globe studied throughout a great part of its thickness and in the mountain masses--have they not had opportunities to convince themselves that the antiquity of this same globe is so great that it is absolutely beyond the power of man to appreciate it in an adequate way! "Assuredly our chronologies do not extend back very far, and they could only have been made by propping them up by fables. Traditions, both oral and written, become necessarily lost, and it is in the nature of things that this should be so. "Even if the invention of printing had been more ancient than it is, what would have resulted at the end of ten thousand years? Everything changes, everything becomes modified, everything becomes lost or destroyed. Every living language insensibly changes its idiom; at the end of a thousand years the writings made in any language can only be read with difficulty; after two thousand years none of these writings will be understood. Besides wars, vandalism, the greediness of tyrants and of those who guide religious opinions, who always rely on the ignorance of the human race and are supported by it, how many are the causes, as proved by history and the sciences, of epochs after epochs of revolutions, which have more or less completely destroyed them. "How many are the causes by which man loses all trace of that which has existed, and cannot believe nor even conceive of the immense antiquity of the earth he inhabits! "How great will yet seem this antiquity of the terrestrial globe in the eyes of man when he shall form a just idea of the origin of living bodies, as also of the causes of the development and of the gradual process of perfection of the organization of these bodies, and especially when it will be conceived that, time and favorable circumstances having been necessary to give existence to all the living species such as we actually see, he is himself the last result and the actual maximum of this process of perfecting, the limit (_terme_) of which, if it exists, cannot be known." In the fourth chapter of the book there is less to interest the reader, since the author mainly devotes it to a reiteration of the ideas of his earlier works on physics and chemistry. He claims that the minerals and rocks composing the earth's crust are all of organic origin, including even granite. The thickness of this crust he thinks, in the absence of positive knowledge, to be from three to four leagues, or from nine to twelve miles. After describing the mode of formation of minerals, including agates, flint, geodes, etc., he discusses the process of fossilization by molecular changes, silicious particles replacing the vegetable or animal matter, as in the case of fossil wood. While, then, the products of animals such as corals and molluscs are limestones, those of vegetables are humus and clay; and all of these deposits losing their less fixed principles pass into a silicious condition, and end by being reduced to quartz, which is the earthy element in its purest form. The salts, pyrites, and metals only differ from other minerals by the different circumstances under which they were accumulated, in their different proportions, and in their much greater amount of carbonic or acidific fire. Regarding granite, which, he says, naturalists very erroneously consider as _primitive_, he begins by observing that it is only by conjecture that we should designate as primitive any matter whatever. He recognizes the fact that granite forms the highest mountains, which are generally arranged in more or less regular chains. But he strangely assumes that the constituents of granite, _i.e._, felspar, quartz, and mica, did not exist before vegetables, and that these minerals and their aggregation into granite were the result of slow deposition in the ocean.[80] He goes so far as to assert that the porphyritic rocks were not thus formed in the sea, but that they are the result of deposits carried down by streams, especially torrents flowing down from mountains. Gneiss, he thinks, resulted from the detritus of granitic rocks, by means of an inappreciable cement, and formed in a way analogous to that of the porphyries. Then he attacks the notion of Leibnitz of a liquid globe, in which all mineral substances were precipitated tumultuously, replacing this idea by his chemical notion of the origin of the crystalline and volcanic rocks. He is on firmer ground in explaining the origin of chalk and clay, for the rocks of the region about Paris, with which he was familiar, are sedimentary and largely of organic origin. In the "Addition" (pp. 173-188) following the fourth chapter Lamarck states that, allowing for the variations in the intensity of the cause of elevation of the land as the result of the accumulations of organic matter, he thinks he can, without great error, consider the mean rate as 324 mm. (1 foot) a century. As a concrete example it has been observed, he says, that one river valley has risen a foot higher in the space of eleven years. Passing by his speculations on the displacement of the poles of the earth, and on the elevations of the equatorial regions, which will dispense with the necessity of considering the earth as originally in a liquid condition, he allows that "the terrestrial globe is not at all a body entirely and truly solid, but that it is a combination (_réunion_) of bodies more or less solid, displaceable in their mass or in their separate parts, and among which there is a great number which undergo continual changes in condition." It was, of course, too early in the history of geology for Lamarck to seize hold of the fact, now so well known, that the highest mountain ranges, as the Alps, Pyrenees, the Caucasus, Atlas ranges, and the Mountains of the Moon (he does not mention the Himalayas) are the youngest, and that the lowest mountains, especially those in the more northern parts of the continents, are but the roots or remains of what were originally lofty mountain ranges. His idea, on the contrary, was, that the high mountain chains above mentioned were the remains of ancient equatorial elevations, which the fresh waters, for an enormous multitude of ages, were in the process of progressively eroding and wearing down. What he says of the formation of coal is noteworthy: "Wherever there are masses of fossil wood buried in the earth, the enormous subterranean beds of coal that are met with in different countries, these are the witnesses of ancient encroachments of the sea, over a country covered with forests; it has overturned them, buried them in deposits of clay, and then after a time has withdrawn." In the appendix he briefly rehearses the laws of evolution as stated in his opening lecture of his course given in the year IX. (1801), and which would be the subject of his projected work, _Biologie_, the third and last part of the Terrestrial Physics, a work which was not published, but which was probably comprised in his _Philosophie zoologique_. The _Hydrogéologie_ closes with a "_Mémoire sur la matière du feu_" and one "_sur la matière du son_," both being reprinted from the _Journal de Physique_. FOOTNOTES: [60] _Evolution in Biology_, in _Darwiniana_, New York, 1896, p. 212. [61] _Principles of Geology_. [62] Lyell's _Principles of Geology_, 8th edit., p. 22. [63] Quoted from Flourens' _Éloge Historique de Georges Cuvier_, Hoefer's edition. Paris, 1854. [64] _Remarques sur les Coquilles fossiles de quelques Cantons de la Touraine_. Mém. Acad. Sc. Paris, 1720, pp. 400-417. [65] _Éloge Historique de Werner_, p. 113. [66] _History of Civilization_, i. p. 627. [67] _France under Louis XV._, p. 359. [68] _France under Louis XV._, p. 360. [69] See vol. iii. of his _Mémoires sur differentes Parties des Sciences et des Arts_, pp. 209-403. Geikie does not give the date of the third volume of his work, but it was apparently about 1771, as vol. ii. was published in 1770. I copy Geikie's account of Guettard's observations often in his own words. [70] Lyell's _Principles of Geology_. [71] Geikie states that the doctrine of the origin of valleys by the erosive action of the streams which flow through them, though it has been credited to various writers, was first clearly taught from actual concrete examples by Desmarest. _L. c._, p. 65. [72] Jameson's _Cuvier's Theory of the Earth_, New York, 1818. [73] J. G. Lehmann of Berlin, in 1756, first formally stated that there was some regular succession in the strata, his observations being based on profiles of the Hartz and the Erzgebirge. He proposed the names Zechstein, Kupferschiefer, rothes Todtliegendes, which still linger in German treatises. G. C. Fuchsel (1762) wrote on the stratigraphy of the coal measures, the Permian and the later systems in Thuringia. (Zittel.) [74] James Hutton was born at Edinburgh, June 3, 1726, where he died March 26, 1797. [75] Quoted from Lyell's _Principles of Geology_, eighth edit., p. 17. [76] _Bulletin Société Imp. des Naturalistes De Moscou_, xlii. (1869), pt. 1. p. 4, quoted from Geikie's _Geology_, p. 276, footnote. [77] Suess also, in his _Anlitz_ etc., substitutes for the folding of the earth's crust by tangential pressure the subsidence by gravity of portions of the crust, their falling in obliging the sea to follow. Suess also explains the later transgressions of the sea by the progressive accumulation of sediments which raise the level of the sea by their deposition at its bottom. Thus he believes that the true factor in the deformation of the globe is vertical descent, and not, as Neumayr had previously thought, the folding of the crust. [78] Bruguière (1750-1799), a conchologist of great merit. His descriptions of new species were clear and precise. In his paper on the coal mines of the mountains of Cevennes (Choix de Mémoires d'Hist. Nat., 1792) he made the first careful study of the coal formation in the Cevennes, including its beds of coal, sandstone, and shale. A. de Jussieu had previously supposed that the immense deposits of coal were due to sudden cataclysms or to one of the great revolutions of the earth during which the seas of the East or West Indies, having been driven as far as into Europe, had deposited on its soil all these exotic plants to be found there, after having torn them up on their way. But Bruguière, who is to be reckoned among the early uniformitarians, says that "the capacity for observation is now too well-informed to be contented with such a theory," and he explains the formation of coal deposits in the following essentially modern way: "The stores of coal, although formed of vegetable substances, owe their origin to the sea. It is when the places where we now find them were covered by its waters that these prodigious masses of vegetable substances were gathered there, and this operation of nature, which astonishes the imagination, far from depending on any extraordinary commotion of the globe, seems, on the contrary, to be only the result of time, of an order of things now existing, and especially that of slow changes" (i, pp. 116, 117). The proofs he brings forward are the horizontality of the beds, both of coal and deposits between them, the marine shells in the sandstones, the fossil fishes intermingled with the plant remains in the shales; moreover, some of the coal deposits are covered by beds of limestone containing marine shells which lived in the sea at a very great depth. The alternation of these beds, the great mass of vegetable matter which lived at small distances from the soil which conceals them, and the occurrence of these beds so high up, show that at this time Europe was almost wholly covered by the sea, the summits of the Alps and the Pyrenees being then, as he says, so many small islands in the midst of the ocean. He also intimates that the climate when these ferns ("bamboo" and "banana") lived was warmer than that of Europe at present. In this essay, then, we see a great advance in correctness of geological observation and reasoning over any previous writers, while its suggestions were appreciated and adopted by Lamarck. [79] Hooke had previously, in order to explain the presence of tropical fossil shells in England, indulged in a variety of speculations concerning changes in the position of the axis of the earth's rotation, "a shifting of the earth's centre of gravity analogous to the revolutions of the magnetic pole, etc." (Lyell's _Principles_). See also p. 132. [80] Cuvier, in a footnote to his _Discours_ (sixth edition, p. 49), in referring to this view, states that it originated with Rodig (_La Physique_, p. 106, Leipzig, 1801) and De Maillet (_Telliamed_, tome ii., p. 169), "also an infinity of new German works." He adds: "M. de Lamarck has recently expanded this system in France at great length in his _Hydrogéologie_ and in his _Philosophie zoologique_." Is the Rodig referred to Ih. Chr. Rodig, author of _Beiträge zur Naturwissenschaft_ (Leipzig, 1803. 8^o)? We have been unable to discover this view in De Maillet; Cuvier's reference to p. 169 is certainly incorrect, as quite a different subject is there discussed. CHAPTER IX LAMARCK THE FOUNDER OF INVERTEBRATE PALÆONTOLOGY It was fortunate for palæontology that the two greatest zoölogists of the end of the eighteenth and the beginning of the nineteenth centuries, Lamarck and Cuvier, lived in the Paris basin, a vast cemetery of corals, shells, and mammals; and not far from extensive deposits of cretaceous rocks packed with fossil invertebrates. With their then unrivalled knowledge of recent or existing forms, they could restore the assemblages of extinct animals which peopled the cretaceous ocean, and more especially the tertiary seas and lakes. Lamarck drew his supplies of tertiary shells from the tertiary beds situated within a radius of from twenty-five to thirty miles from the centre of Paris, and chiefly from the village of Grignon, about ten miles west of Paris, beyond Versailles, and still a rich collecting ground for the students of the Museum and Sorbonne. He acknowledges the aid received from Defrance,[81] who had already collected at Grignon five hundred species of fossil shells, three-fourths of which, he says, had not then been described. Lamarck's first essay ("_Sur les fossiles_") on fossils in general was published at the end of his _Système des Animaux sans Vertèbres_ (pp. 401-411), in 1801, a year before the publication of the _Hydrogéologie_. "I give the name _fossils_," he says, "to remains of living beings, changed by their long sojourn in the earth or under water, but whose forms and structure are still recognizable. "From this point of view, the bones of vertebrate animals and the remains of testaceous molluscs, of certain crustacea, of many echinoderms, coral polyps, when after having been for a long time buried in the earth or hidden under the sea, will have undergone an alteration which, while changing their substance, has nevertheless destroyed neither their forms, their figures, nor the special features of their structures." He goes on to say that the animal parts having been destroyed, the shell remains, being composed of calcareous matter. This shell, then, has lost its lustre, its colors, and often even its nacre, if it had any; and in this altered condition it is usually entirely white. In some cases where the shells have remained for a long period buried in a mud of some particular color, the shell receives the same color. "In France, the fossil shells of Courtagnon near Reims, Grignon near Versailles, of what was formerly Touraine, etc., are almost all still in this calcareous state, having more or less completely lost their animal parts--namely, their lustre, their peculiar colors, and their nacre. "Other fossils have undergone such an alteration that not only have they lost their animal portion, but their substance has been changed into a silicious matter. I give to this second kind of fossil the name of _silicious fossils_, and examples of this kind are the different oysters ('des ostracites'), many terebratulæ ('des terebratulites'), trigoniæ, ammonites, echinites, encrinites, etc. "The fossils of which I have just spoken are in part buried in the earth, and others lie scattered over its surface. They occur in all the exposed parts of our globe, in the middle even of the largest continents, and, what is very remarkable, they occur on mountains up to very considerable altitudes. In many places the fossils buried in the earth form banks extending several leagues in length."[82] Conchologists, he says, did not care to collect or study fossil shells, because they had lost their lustre, colors, and beauty, and they were rejected from collections on this account as "dead" and uninteresting. "But," he adds, "since attention has been drawn to the fact that these fossils are extremely valuable _monuments_ for the study of the revolutions which have taken place in different regions of the earth, and of the changes which the beings living there have themselves successively undergone (in my lectures I have always insisted on these considerations), consequently the search for and study of fossils have excited special interest, and are now the objects of the greatest interest to naturalists." Lamarck then combats the views of several naturalists, undoubtedly referring to Cuvier, that the fossils are extinct species, and that the earth has passed through a general catastrophe (_un bouleversement universel_) with the result that a multitude of species of animals and plants were consequently absolutely lost or destroyed, and remarks in the following telling and somewhat derisive language: "A universal catastrophe (_bouleversement_) which necessarily regulates nothing, mixes up and disperses everything, is a very convenient way to solve the problem for those naturalists who wish to explain everything, and who do not take the trouble to observe and investigate the course followed by nature as respects its production and everything which constitutes its domain. I have already elsewhere said what should be thought of this so-called universal overturning of the globe; I return to fossils. "It is very true that, of the great quantity of fossil shells gathered in the different countries of the earth, there are yet but a very small number of species whose living or marine analogues are known. Nevertheless, although this number may be very small, which no one will deny, it is enough to suppress the universality announced in the proposition cited above. "It is well to remark that among the fossil shells whose marine or living analogues are not known, there are many which have a form closely allied to shells of the same genera known to be now living in the sea. However, they differ more or less, and cannot be rigorously regarded as the same species as those known to be living, since they do not perfectly resemble them. These are, it is said, extinct species. "I am convinced that it is possible never to find, among fresh or marine shells, any shells perfectly similar to the fossil shells of which I have just spoken. I believe I know the reason; I proceed to succinctly indicate, and I hope that it will then be seen, that although many fossil shells are different from all the marine shells known, this does not prove that the species of these shells are extinct, but only that these species have changed as the result of time, and that actually they have different forms from those individuals whose fossil remains we have found." Then he goes on in the same strain as in the opening discourse, saying that nothing terrestrial remains constant, that geological changes are continually occurring, and that these changes produce in living organisms a diversity of habits, a different mode of life, and as the result modifications or developments in their organs and in the shape of their parts. "We should still realize that all the modifications which the organism undergoes in its structure and form as the result of the influence of circumstances which would influence this being, are propagated by generation, and that after a long series of ages not only will it be able to form new species, new genera, and even new orders, but also each species will even necessarily vary in its organization and in its forms. "We should not be more surprised then if, among the numerous fossils which occur in all the dry parts of the globe and which offer us the remains of so many animals which have formerly existed, there should be found so few of which we know the living analogues. If there is in this, on the contrary, anything which should astonish us, it is to find that among these numerous fossil remains of beings which have lived there should be known to us some whose analogues still exist, from a germ to a vast multitude of living forms, of different and ascending grades of perfection, ending in man. "This fact, as our collection of fossils proves, should lead us to suppose that the fossil remains of the animals whose living analogues we know are the less ancient fossils. The species to which each of them belongs had doubtless not yet time to vary in any of its forms. "We should, then, never expect to find among the living species the totality of those that we meet with in the fossil state, and yet we cannot conclude that any species can really be lost or extinct. It is undoubtedly possible that among the largest animals some species have been destroyed as a result of the multiplication of man in the regions where they live. But this conjecture cannot be based on the consideration of fossils alone; we can only form an opinion in this respect when all the inhabited parts of the globe will have become perfectly known." Lamarck did not have, as we now have, a knowledge of the geological succession of organic forms. The comparatively full and detailed view which we possess of the different vast assemblages of plant and animal life which have successively peopled the surface of our earth is a vision on which his eyes never rested. His slight, piecemeal glimpse of the animal life of the Paris Basin, and of the few other extinct forms then known, was all he had to depend upon or reason from. He was not disposed to believe that the thread of life once begun in the earliest times could be arbitrarily broken by catastrophic means; that there was no relation whatever between the earlier and later faunas. He utterly opposed Cuvier's view that species once formed could ever be lost or become extinct without ancestors or descendants. He on the contrary believed that species underwent a slow modification, and that the fossil forms are the ancestors of the animals now living. Moreover, Lamarck was the inventor of the first genealogical tree; his phylogeny, in the second volume of his _Philosophie zoologique_ (p. 463), proves that he realized that the forms leading up to the existing ones were practically extinct, as we now use the word. Lamarck in theory was throughout, as Houssay well says, at one with us who are now living, but a century behind us in knowledge of the facts needed to support his theory. In this first published expression of his views on palæontology, we find the following truths enumerated on which the science is based: (1) The great length of geological time; (2) The continuous existence of animal life all through the different geological periods without sudden total extinctions and as sudden recreations of new assemblages; (3) The physical environment remaining practically the same throughout in general, but with (4) continual gradual but not catastrophic changes in the relative distribution of land and sea and other modifications in the physical geography, changes which (5) caused corresponding changes in the habitat, and (6) consequently in the habits of the living beings; so that there has been all through geological history a slow modification of life-forms. Thus Lamarck's idea of creation is _evolutional_ rather than _uniformitarian_. There was, from his point of view, not simply a uniform march along a dead level, but a progression, a change from the lower or generalized to the higher or specialized--an evolution or unfolding of organic life. In his effort to disprove catastrophism he failed to clearly see that species, as we style them, became extinct, though really the changes in the species practically amounted to extinctions of the earlier species as such. The little that was known to Lamarck at the time he wrote, prevented his knowing that species became extinct, as we say, or recognizing the fact that while some species, genera, and even orders may rise, culminate, and die, others are modified, while a few persist from one period to another. He did, however, see clearly that, taking plant and animal life as a whole, it underwent a slow modification, the later forms being the descendants of the earlier; and this truth is the central one of modern palæontology. Lamarck's first memoir on fossil shells, in which he described many new species, was published in 1802, after the appearance of his _Hydrogéologie_, to which he refers. It was the first of a series of descriptive papers, which appeared at intervals from 1802 to 1806. He does not fail to open the series of memoirs with some general remarks, which prove his broad, philosophic spirit, that characterizing the founder of a new science. He begins by saying that the fossil forms have their analogues in the tropical seas. He claims that there was evident proof that these molluscs could not have lived in a climate like that of places in which they now occur, instancing _Nautilius pompilius_, which now lives in the seas of warm countries; also the presence of exotic ferns, palms, fossil amber, fossil gum elastic, besides the occurrence of fossil crocodiles and elephants both in France and Germany.[83] Hence there have been changes of climate since these forms flourished, and, he adds, the intervals between these changes of climate were stationary periods, whose duration was practically without limit. He assigns a duration to these stationary or intermediate periods of from three to five million years each--"a duration infinitely small relative to those required for all the changes of the earth's surface." He refers in an appreciative way to the first special treatise on fossil shells ever published, that of an Englishman named Brander,[84] who collected the shells "out of the cliffs by the sea-coast between Christ Church and Lymington, but more especially about the cliffs by the village of Hordwell," where the strata are filled with these fossils. Lamarck, working upon collections of tertiary shells from Grignon and also from Courtagnon near Reims, with the aid of Brander's work showed that these beds, not known to be Eocene, extended into Hampshire, England; thus being the first to correlate by their fossils, though in a limited way to be sure, the tertiary beds of France with those of England. How he at a later period (1805) regarded fossils and their relations to geology may be seen in his later memoirs, _Sur les Fossiles des environs de Paris_.[85] "The determination of the characters, both generic and specific, of animals of which we find the fossil remains in almost all the dry parts of the continents and large islands of our globe will be, from several points of view, a thing extremely useful to the progress of natural history. At the outset, the more this determination is advanced, the more will it tend to complete our knowledge in regard to the species which exist in nature and of those which have existed, as it is true that some of them have been lost, as we have reason to believe, at least as concerns the large animals. Moreover, this same determination will be singularly advantageous for the advancement of geology; for the fossil remains in question may be considered, from their nature, their condition, and their situation, as authentic monuments of the revolutions which the surface of our globe has undergone, and they can throw a strong light on the nature and character of these revolutions." This series of papers on the fossils of the Paris tertiary basin extended through the first eight volumes of the _Annales_, and were gathered into a volume published in 1806. In his descriptions his work was comparative, the fossil species being compared with their living representatives. The thirty plates, containing 483 figures representing 184 species (exclusive of those figured by Brard), were afterwards published, with the explanations, but not the descriptions, as a separate volume in 1823.[86] This (the text published in 1806) is the first truly scientific palæontological work ever published, preceding Cuvier's _Ossemens fossiles_ by six years. When we consider Lamarck's--at his time unrivalled--knowledge of molluscs, his philosophical treatment of the relations of the study of fossils to geology, his correlation of the tertiary beds of England with those of France, and his comparative descriptions of the fossil forms represented by the existing shells, it seems not unreasonable to regard him as the founder of invertebrate palæontology, as Cuvier was of vertebrate or mammalian palæontology. We have entered the claim that Lamarck was one of the chief founders of palæontology, and the first French author of a genuine, detailed palæontological treatise. It must be admitted, therefore, that the statement generally made that Cuvier was the founder of this science should be somewhat modified, though he may be regarded as the chief founder of vertebrate palæontology. In this field, however, Cuvier had his precursors not only in Germany and Holland, but also in France. Our information as to the history of the rise of vertebrate palæontology is taken from Blainville's posthumous work entitled _Cuvier et Geoffroy Saint-Hilaire_.[87] In this work, a severe critical and perhaps not always sufficiently appreciative account of Cuvier's character and work, we find an excellent history of the first beginnings of vertebrate palæontology. Blainville has little or nothing to say of the first steps in invertebrate palæontology, and, singularly enough, not a word of Lamarck's principles and of his papers and works on fossil shells--a rather strange oversight, because he was a friend and admirer of Lamarck, and succeeded him in one of the two departments of invertebrates created at the Museum d'Histoire Naturelle after Lamarck's death. Blainville, who by the way was the first to propose the word _palæontology_, shows that the study of the great extinct mammals had for forty years been held in great esteem in Germany, before Faujas and Cuvier took up the subject in France. Two Frenchmen, also before 1789, had examined mammalian bones. Thus Bernard de Jussieu knew of the existence in a fossil state of the teeth of the hippopotamus. Guettard[88] published in 1760 a memoir on the fossil bones of Aix en Provence. Lamanon (1780-1783)[89] in a beautiful memoir described a head, almost entire, found in the gypsum beds of Paris. Daubenton had also slightly anticipated Cuvier's law of correlation, giving "a very remarkable example of the mode of procedure to follow in order to solve these kinds of questions by the way in which he had recognized a bone of a giraffe whose skeleton he did not possess" (De Blainville). "But it was especially in Germany, in the hands of Pallas, Camper, Blumenbach, anatomists and physicians, also those of Walch, Merck, Hollmann, Esper, Rosenmüller, and Collini (who was not, however, occupied with natural history), of Beckman, who had even discussed the subject in a general way (_De reductione rerum fossilium ad genera naturalia prototyporum--Nov. Comm. Soc. Scient. Goettingensis_, t. ii.), that palæontology applied to quadrupeds had already settled all that pertained to the largest species." As early as 1764, Hollmann[90] had admirably identified the bones of a rhinoceros found in a bone-deposit of the Hartz, although he had no skeleton of this animal for comparison. Pallas, in a series of memoirs dating from 1773, had discovered and distinguished the species of Siberian elephant or mammoth, the rhinoceros, and the large species of oxen and buffalo whose bones were found in such abundance in the quaternary deposits of Siberia; and, as Blainville says, if he did not distinguish the species, it was because at this epoch the question of the distinction of the two species of rhinoceros and of elephants, in the absence of material, could not be solved. This solution, however, was made by the Dutch anatomist Camper, in 1777, who had brought together at Amsterdam a collection of skeletons and skulls of the existing species which enabled him for the first time to make the necessary comparisons between the extinct and living species. A few years later (1780) Blumenbach confirmed Camper's identification, and gave the name of _Elephas primigenius_ to the Siberian mammoth. "Beckman" [says Blainville] "as early as 1772 had even published a very good memoir on the way in which we should consider fossil organic bodies; he was also the first to propose using the name _fossilia_ instead of _petrefacta_, and to name the science which studies fossils _Oryctology_. It was also he who admitted that these bodies should be studied with reference to the class, order, genus, species, as we would do with a living being, and he compared them, which he called _prototypes_,[91] with their analogues. He then passes in review, following the zoölogical order, the fossils which had been discovered by naturalists. He even described one of them as a new species, besides citing, with an erudition then rare, all the authors and all the works where they were described. He did no more than to indicate but not name each species. Thus he was the means of soon producing a number of German authors who made little advance from lack of anatomical knowledge; but afterwards the task fell into the hands of men capable of giving to the newly created palæontology a remarkable impulse, and one which since then has not abated." Blumenbach,[92] the most eminent and all-round German anatomist and physiologist of his time, one of the founders of anthropology as well as of palæontology, had meanwhile established the fact that there were two species of fossil cave-bear, which he named _Ursus spelæus_ and _U. arctoideus_. He began to publish his _Archæologia telluris_,[93] the first part of which appeared in 1803. From Blainville's useful summary we learn that Blumenbach, mainly limiting his work to the fossils of Hanover, aimed at studying fossils in order to explain the revolutions of the earth. "Hence the order he proposed to follow was not that commonly followed in treatises on oryctology, namely, systematic, following the classes and the orders of the animal and vegetable kingdom, but in a chronological order, in such a way as to show that the classes, so far as it was possible to conjecture with any probability, were established after or in consequence of the different revolutions of the earth. "Thus, as we see, all the great questions, more or less insoluble, which the study of fossil organic bodies can offer, were raised and even discussed by the celebrated professor of Göttingen as early as 1803, before anything of the sort could have arisen from the essays of M. G. Cuvier; the errors of distribution in the classes committed by Blumenbach were due to the backward state of geology." The political troubles of Germany, which also bore heavily upon the University of Göttingen, probably brought Blumenbach's labors to an end, for after a second "specimen" of his work, of less importance than the first, the _Archæologia telluris_ was discontinued. The French geologist Faujas,[94] who also published several articles on fossil animals, ceased his labors, and now Cuvier began his memorable work. The field of the labors and triumphs of palæontology were now transferred to France. We have seen that the year 1793, when Lamarck and Geoffroy Saint-Hilaire were appointed to fill the new zoölogical chairs, and the latter had in 1795 called Cuvier from Normandy to Paris, was a time of renascence of the natural sciences in France. Cuvier began a course of lectures on comparative anatomy at the Museum of Natural History. He was more familiar than any one else in France with the progress in natural science in Germany, and had felt the stimulus arising from this source; besides, as Blainville stated, he was also impelled by the questions boldly raised by Faujas in his geological lectures, who was somewhat of the school of Buffon. Cuvier, moreover, had at his disposition the collection of skeletons of the Museum, which was frequently increased by those of the animals which died in the menagerie. With his knowledge of comparative anatomy, of which, after Vicq-d'Azyr, he was the chief founder, and with the gypsum quarry of Montmartre, that rich cemetery of tertiary mammals, to draw from, he had the whole field before him, and rapidly built up his own vast reputation and thus added to the glory of France. His first contribution to palæontology[95] appeared in 1798, in which he announced his intention of publishing an extended work on fossil bones of quadrupeds, to restore the skeletons and to compare them with those now living, and to determine their relations and differences; but, says Blainville, in the list of thirty or forty species which he enumerates in his tableau, none was apparently discovered by him, unless it was the species of "dog" of Montmartre, which he afterward referred to his new genera Palæotherium and Anaplotherium. In 1801 (le 26 brumaire, an IX.) he published, by order of the Institut, the programme of a work on fossil quadrupeds, with an increased number of species; but, as Blainville states, "It was not until 1804, and in tome iii. of the _Annales du Muséum_, namely, more than three years after his programme, that he began his publications by fragments and without any order, while these publications lasted more than eight years before they were collected into a general work"; this "_corps d'ouvrage_" being the _Ossemens fossiles_, which was issued in 1812 in four quarto volumes, with an atlas of plates. It is with much interest, then, that we turn to Cuvier's great work, which brought him such immediate and widespread fame, in order to see how he treated his subject. His general views are contained in the preliminary remarks in his well-known "Essay on the Theory of the Earth" (1812), which was followed in 1821 by his _Discours sur les Révolutions de la Surface du Globe_. It was written in a more attractive and vigorous style than the writings of Lamarck, more elegant, concise, and with less repetition, but it is destitute of the philosophic grasp, and is not the work of a profound thinker, but rather of a man of talent who was an industrious collector and accurate describer of fossil bones, of a high order to be sure, but analytical rather than synthetical, of one knowing well the value of carefully ascertained and demonstrated facts, but too cautious, if he was by nature able to do so, to speculate on what may have seemed to him too few facts. It is also the work of one who fell in with the current views of the time as to the general bearing of his discoveries on philosophy and theology, believing as he did in the universality of the Noachian deluge. Like Lamarck, Cuvier independently made use of the comparative method, the foundation method in palæontology; and Cuvier's well-known "law of correlation of structures," so well exemplified in the vertebrates, was a fresh, new contribution to philosophical biology. In his _Discours_, speaking of the difficulty of determining the bones of fossil quadrupeds, as compared with fossil shells or the remains of fishes, he remarks:[96] "Happily comparative anatomy possessed a principle which, well developed, was capable of overcoming every difficulty; it was that of the correlation of forms in organic beings, by means of which each kind of organism can with exactitude be recognized by every fragment of each of its parts.--Every organized being," he adds, "forms an entire system, unique and closed, whose organs mutually correspond, and concur in the same definite action by a reciprocal reaction. Hence none of these parts can change without the other being also modified, and consequently each of them, taken separately, indicates and produces (_donne_) all the others. "A claw, a shoulder-blade, a condyle, a leg or arm-bone, or any other bone separately considered, enables us to discover the kind of teeth to which they have belonged; so also reciprocally we may determine the form of the other bones from the teeth. Thus, commencing our investigation by a careful survey of any one bone by itself, a person who is sufficiently master of the laws of organic structure can reconstruct the entire animal. The smallest facet of bone, the smallest apophysis, has a determinate character, relative to the class, the order, the genus, and the species to which it belongs, so that even when one has only the extremity of a well-preserved bone, he can, with careful examination, assisted by analogy and exact comparison, determine all these things as surely as if he had before him the entire animal." Cuvier adds that he has enjoyed every kind of advantage for such investigations owing to his fortunate situation in the Museum of Natural History, and that by assiduous researches for nearly thirty years[97] he has collected skeletons of all the genera and sub-genera of quadrupeds, with those of many species in certain genera, and several individuals of certain species. With such means it was easy for him to multiply his comparisons, and to verify in all their details the applications of his laws. Such is the famous law of correlation of parts, of Cuvier. It could be easily understood by the layman, and its enunciation added vastly to the popular reputation and prestige of the young science of comparative anatomy.[98] In his time, and applied to the forms occurring in the Paris Basin, it was a most valuable, ingenious, and yet obvious method, and even now is the principal rule the palæontologist follows in identifying fragments of fossils of any class. But it has its limitations, and it goes without saying that the more complete the fossil skeleton of a vertebrate, or the remains of an arthropod, the more complete will be our conception of the form of the extinct organism. It may be misleading in the numerous cases of convergence and of generalized forms which now abound in our palæontological collections. We can well understand how guarded one must be in working out the restorations of dinosaurs and fossil birds, of the Permian and Triassic theromorphs, and the Tertiary creodonts as compared with existing carnivora. As the late O. C. Marsh[99] observed: "We know to-day that unknown extinct animals cannot be restored from a single tooth or claw unless they are very similar to forms already known. Had Cuvier himself applied his methods to many forms from the early tertiary or older formations he would have failed. If, for instance, he had had before him the disconnected fragments of an eocene tillodont he would undoubtedly have referred a molar tooth to one of his pachyderms, an incisor tooth to a rodent, and a claw bone to a carnivore. The tooth of a Hesperornis would have given him no possible hint of the rest of the skeleton, nor its swimming feet the slightest clue to the ostrich-like sternum or skull. And yet the earnest belief in his own methods led Cuvier to some of his most important discoveries." Let us now examine from Cuvier's own words in his _Discours_, not relying on the statements of his expositors or followers, just what he taught notwithstanding the clear utterances of his older colleague, Lamarck, whose views he set aside and either ignored or ridiculed.[100] ~ ~ ~ ~ ~ He at the outset affirms that nature has, like mankind, also had her intestine wars, and that "the surface of the globe has been much convulsed by successive revolutions and various catastrophes." As first proof of the revolutions on the surface of the earth he instances fossil shells, which in the lowest and most level parts of the earth are "almost everywhere in such a perfect state of preservation that even the smallest of them retain their most delicate parts, their sharpest ridges, and their finest and tenderest processes." "We are therefore forcibly led to believe not only that the sea has at one period or another covered all our plains, but that it must have remained there for a long time and in a state of tranquillity, which circumstance was necessary for the formation of deposits so extensive, so thick, in part so solid, and filled with the exuviæ of aquatic animals." But the traces of revolutions become still more marked when we ascend a little higher and approach nearer to the foot of the great mountain chains. Hence the strata are variously inclined, and at times vertical, contain shells differing specifically from those of beds on the plains below, and are covered by horizontal later beds. Thus the sea, previous to the formation of the horizontal strata, had formed others, which by some means have been broken, lifted up, and overturned in a thousand ways. There had therefore been also at least one change in the basin of that sea which preceded ours; it had also experienced at least one revolution. He then gives proofs that such revolutions have been numerous. "Thus the great catastrophes which have produced revolutions in the basins of the sea were preceded, accompanied, and followed by changes in the nature of the fluid and of the substances which it held in solution, and when the surface of the seas came to be divided by islands and projecting ridges, different changes took place in every separate basin." We now come to the Cuvierian doctrine _par excellence_, one in which he radically differs from Lamarck's views as to the genetic relations between the organisms of successive strata. "Amid these changes of the general fluid it must have been almost impossible for the same kind of animals to continue to live, nor did they do so in fact. Their species, and even their genera, change with the strata, and although the same species occasionally recur at small distances, it is generally the case that the shells of the ancient strata have forms peculiar to themselves; that they gradually disappear till they are not to be seen at all in the recent strata, still less in the existing seas, in which, indeed, we never discover their corresponding species, and where several even of their genera are not to be found; that, on the contrary, the shells of the recent strata resemble, as regards the genus, those which still exist in the sea, and that in the last formed and loosest of these strata there are some species which the eye of the most expert naturalists cannot distinguish from those which at present inhabit the ocean. "In animal nature, therefore, there has been a succession of changes corresponding to those which have taken place in the chemical nature of the fluid; and when the sea last receded from our continent its inhabitants were not very different from those which it still continues to support." He then refers to successive irruptions and retreats of the sea, "the final result of which, however, has been a universal depression of the level of the sea." "These repeated irruptions and retreats of the sea have neither been slow nor gradual; most of the catastrophes which have occasioned them have been sudden." He then adds his proofs of the occurrence of revolutions before the existence of living beings. Like Lamarck, Cuvier was a Wernerian, and in speaking of the older or primitive crystalline rocks which contain no vestige of fossils, he accepted the view of the German theorist in geology, that granites forming the axis of mountain chains were formed in a fluid. We must give Cuvier the credit of fully appreciating the value of fossils as being what he calls "historical documents," also for appreciating the fact that there were a number of revolutions marking either the incoming or end of a geological period; but as he failed to perceive the unity of organization in organic beings, and their genetic relationship, as had been indicated by Lamarck and by Geoffroy St. Hilaire, so in geological history he did not grasp, as did Lamarck, the vast extent of geological time, and the general uninterrupted continuity of geological events. He was analytic, thoroughly believing in the importance of confining himself to the discovery of facts, and, considering the multitude of fantastic hypotheses and suggestions of previous writers of the eighteenth century, this was sound, sensible, and thoroughly scientific. But unfortunately he did not stop here. Master of facts concerning the fossil mammals of the Paris Basin, he also--usually cautious and always a shrewd man of the world--fell into the error of writing his "theory of the world," and of going to the extreme length of imagining universal catastrophes where there are but local ones, a universal Noachian deluge when there was none, and of assuming that there were at successive periods thoroughgoing total and sudden extinctions of life, and as sudden recreations. Cuvier was a natural leader of men, a ready debater, and a clear, forcible writer, a man of great executive force, but lacking in insight and imagination; he dominated scientific Paris and France, he was the law-giver and autocrat of the laboratories of Paris, and the views of quiet, thoughtful, profound scholars such as Lamarck and Geoffroy St. Hilaire were disdainfully pushed aside, overborne, and the progress of geological thought was arrested, while, owing to his great prestige, the rising views of the Lamarckian school were nipped in the bud. Every one, after the appearance of Cuvier's great work on fossil mammals and of his _Règne Animal_, was a Cuvierian, and down to the time of Lyell and of Charles Darwin all naturalists, with only here and there an exception, were pronounced Cuvierians in biology and geology--catastrophists rather than uniformitarians. We now, with the increase of knowledge of physical and historical geology, of the succession of life on the earth, of the unity of organization pervading that life from monad to man all through the ages from the Precambrian to the present age, know that there were vast periods of preparation followed by crises, perhaps geologically brief, when there were widespread changes in physical geography, which reacted on the life-forms, rendering certain ones extinct, and modifying others; but this conception is entirely distinct from the views of Cuvier and his school,[101] which may, in the light of our present knowledge, properly be deemed not only totally inadequate, but childish and fantastic. Cuvier cites the view of Dolomieu, the well-known geologist and mineralogist (1770-1801), only, however, to reject it, who went to the extent of supposing that "tides of seven or eight hundred fathoms have carried off from time to time the bottom of the ocean, throwing it up in mountains and hills on the primitive valleys and plains of the continents" (Dolomieu in _Journal de Physique_). Cuvier met with objections to his extreme views. In his discourse he thus endeavors to answer "the following objection" which "has already been stated against my conclusions": "Why may not the non-existing races of mammiferous land quadrupeds be mere modifications or varieties of those ancient races which we now find in the fossil state, which modifications may have been produced by change of climate and other local circumstances, and since raised to the present excessive differences by the operation of similar causes during a long succession of ages? "This objection may appear strong to those who believe in the indefinite possibility of change of forms in organized bodies, and think that during a succession of ages, and by alternations of habits, all the species may change into each other, or one of them give birth to all the rest. Yet to these persons the following answer may be given from their own system: If the species have changed by degrees, as they assume, we ought to find traces of this gradual modification. Thus, between the Palæotherium and the species of our own days, we should be able to discover some intermediate forms; and yet no such discovery has ever been made. Since the bowels of the earth have not preserved monuments of this strange genealogy, we have a right to conclude that the ancient and now extinct species were as permanent in their forms and characters as those which exist at present; or, at least, that the catastrophe which destroyed them did not have sufficient time for the production of the changes that are alleged to have taken place." Cuvier thus emphatically rejects all idea that any of the tertiary mammals could have been the ancestral forms of those now existing. "From all these well-established facts, there does not seem to be the smallest foundation for supposing that the new genera which I have discovered or established among extraneous fossils, such as the _palæotherium_, _anaplotherium_, _megalonynx_, _mastodon_, _pterodactylis_, etc., have ever been the sources of any of our present animals, which only differ as far as they are influenced by time or climate. Even if it should prove true, which I am far from believing to be the case, that the fossil elephants, rhinoceroses, elks, and bears do not differ further from the present existing species of the same genera than the present races of dogs differ among themselves, this would by no means be a sufficient reason to conclude that they were of the same species; since the races or varieties of dogs have been influenced by the trammels of domestication, which these other animals never did and indeed never could experience."[102] The extreme views of Cuvier as to the frequent renewal and extinction of life were afterward (in 1850) carried out to an exaggerated extent by D'Orbigny, who maintained that the life of the earth must have become extinct and again renewed twenty-seven times. Similar views were held by Agassiz, who, however, maintained the geological succession of animals and the parallelism between their embryonic development and geological succession, the two foundation stones of the biogenetic law of Haeckel. But immediately after the publication of Cuvier's _Ossemens fossiles_, as early as 1813, Von Schlotheim, the founder of vegetable palæontology, refused to admit that each set of beds was the result of such a thoroughgoing revolution.[103] At a later date Bronn "demonstrated that certain species indeed really passed from one formation to another, and though stratigraphic boundaries are often barriers confining the persistence of some form, still this is not an absolute rule, since the species in nowise appear in their entirety."[104] At present the persistence of genera like Saccamina, Lingula, Ceratodus, etc., from one age to another, or even through two or more geological ages, is well known, while _Atrypa reticulatus_, a species of world-wide distribution, lived from near the beginning of the Upper Silurian to the Waverly or beginning of the Carboniferous age. Such were the views of the distinguished founder of vertebrate palæontology. When we compare the _Hydrogéologie_ of Lamarck with Cuvier's _Discours_, we see, though some erroneous views, some very fantastic conceptions are held, in common with others of his time, in regard to changes of level of the land and the origin of the crystalline rocks, that it did contain the principles upon which modern palæontology is founded, while those of Cuvier are now in the limbo--so densely populated--of exploded, ill-founded theories. Our claim that Lamarck should share with Cuvier the honor of being a founder of palæontology[105] is substantiated by the philosophic Lyell, who as early as 1836, in his _Principles of Geology_, expresses the same view in the following words: "The labors of Cuvier in comparative osteology, and of Lamarck in recent and fossil shells, had raised these departments of study to a rank of which they had never previously been deemed susceptible." Our distinguished American palæontologist, the late O. C. Marsh, takes the same view, and draws the following parallel between the two great French naturalists: "In looking back from this point of view, the philosophical breadth of Lamarck's conclusions, in comparison with those of Cuvier, is clearly evident. The invertebrates on which Lamarck worked offered less striking evidence of change than the various animals investigated by Cuvier; yet they led Lamarck directly to evolution, while Cuvier ignored what was before him on this point, and rejected the proof offered by others. Both pursued the same methods, and had an abundance of material on which to work, yet the facts observed induced Cuvier to believe in catastrophes, and Lamarck in the uniform course of nature. Cuvier declared species to be permanent; Lamarck, that they were descended from others. Both men stand in the first rank in science; but Lamarck was the prophetic genius, half a century in advance of his time."[106] FOOTNOTES: [81] Although Defrance (born 1759, died in 1850) aided Lamarck in collecting tertiary shells, his earliest palæontological paper (on Hipponyx) did not appear until the year 1819. [82] In a footnote Lamarck refers to an unpublished work, which probably formed a part of the _Hydrogéologie_, published in the following year. "_Voyez à ce sujet mon ouvrage intitulé: De l'influence du mouvement des eaus sur la surface du globe terrestre, et des indices du déplacement continuel du bassin des mers, ainsi que de son transport successif sur les différens points de la surface du globe_" (no date). [83] It should be stated that the first observer to inaugurate the comparative method was that remarkable forerunner of modern palæontologists, Steno the Dane, who was for a while a professor at Padua. In 1669, in his treatise entitled _De Solido intra Solidum naturaliter contento_, which Lyell translates "On gems, crystals, and organic petrefactions inclosed within solid rocks," he showed, by dissecting a shark from the Mediterranean, that certain fossil teeth found in Tuscany were also those of some shark. "He had also compared the shells discovered in the Italian strata with living species, pointed out their resemblance, and traced the various gradations from shells merely calcined, or which had only lost their animal gluten, to those petrefactions in which there was a perfect substitution of stony matter" (Lyell's _Principles_, p. 25). About twenty years afterwards, the English philosopher Robert Hooke, in a discourse on earthquakes, written in 1688, but published posthumously in 1705, was aware that the fossil ammonites, nautili, and many other shells and fossil skeletons found in England, were of different species from any then known; but he doubted whether the species had become extinct, observing that the knowledge of naturalists of all the marine species, especially those inhabiting the deep sea, was very deficient. In some parts of his writings, however, he leans to the opinion that species had been lost. Some species, he observes with great sagacity, "are _peculiar to certain places_, and not to be found elsewhere." Turtles and such large ammonites as are found in Portland seem to have been the productions of hotter countries, and he thought that England once lay under the sea within the torrid zone (Lyell's _Principles_). Gesner the botanist, of Zurich, also published in 1758 an excellent treatise on petrefactions and the changes of the earth which they testify. He observed that some fossils, "such as ammonites, gryphites, belemnites, and other shells, are either of unknown species or found only in the Indian and other distant seas" (Lyell's _Principles_). Geikie estimates very highly Guettard's labors in palæontology, saying that "his descriptions and excellent drawings entitle him to rank as the first great leader of the palæontological school of France." He published many long and elaborate memoirs containing brief descriptions, but without specific names, and figured some hundreds of fossil shells. He was the first to recognize trilobites (Illænus) in the Silurian slates of Angers, in a memoir published in 1762. Some of his generic names, says Geikie, "have passed into the languages of modern palæontology," and one of the genera of chalk sponges which he described has been named after him, _Guettardia_. In his memoir "On the accidents that have befallen fossil shells compared with those which are found to happen to shells now living in the sea" (Trans. Acad. Roy. Sciences, 1765, pp. 189, 329, 399) he shows that the beds of fossil shells on the land present the closest possible analogy to the flow of the present sea, so that it becomes impossible to doubt that the accidents, such as broken and worn shells, which have affected the fossil organisms, arose from precisely the same causes as those of exactly the same nature that still befall their successors on the existing ocean bottom. On the other hand, Geikie observes that it must be acknowledged "that Guettard does not seem to have had any clear ideas of the sequence of formations and of geological structures." [84] Scheuchzer's "Complaint and Vindication of the Fishes" (_Piscium Querelae et Vindiciae_, Germany, 1708), "a work of zoölogical merit, in which he gave some good plates and descriptions of fossil fish" (Lyell). Gesner's treatise on petrefactions preceded Lamarck's work in this direction, as did Brander's _Fossillia Hantoniensia_, published in 1766, which contained "excellent figures of fossil shells from the more modern (or Eocene) marine strata of Hampshire. In his opinion fossil animals and testacea were, for the most part, of unknown species, and of such as were known the living analogues now belonged to southern latitudes" (Lyell's _Principles_, eighth edition, p. 46). [85] _Annales du Muséum d'Histoire Naturelle_, vi., 1805, pp. 222-228. [86] _Recueil de Planches des Coquilles fossiles des environs de Paris_ (Paris, 1823). There are added two plates of fossil fresh-water shells (twenty-one species of Limnæa, etc.) by Brard, with sixty-two figures. [87] _Cuvier et Geoffroy Saint-Hilaire. Biographies scientifiques_, par Ducrotay de Blainville (Paris, 1890, p. 446). [88] "Mémoire sur des os fossiles découverts auprès de la ville d'Aix en Provence" (Mém. Acad. Sc., Paris, 1760, pp. 209-220). [89] "Sur un os d'une grosseur énorme qu'on a trouvé dans une couche de glaise au milieu de Paris; et en général sur les ossemens fossiles qui ont appartenu à de grands animaux" (_Journal de Physique_, tome xvii., 1781. pp. 393-405). Lamanon also, in 1780, published in the same _Journal_ an article on the nature and position of the bones found at Aix en Provence; and in 1783 another article on the fossil bones belonging to gigantic animals. [90] Hollmann had still earlier published a paper entitled _De corporum marinorum, aliorumque peregrinorum in terra continente origine_ (_Commentarii Soc. Goettingen._, tom. iii., 1753, pp. 285-374). [91] _Novi Commentarii Soc. Sc. Goettingensis_, tom. ii., _Commentat._, tom. i. [92] His first palæontological article appears to have been one entitled _Beiträge zur Naturgeschichte der Vorwelt_ (Lichtenberg, _Voigt's Magaz._, Bd. vi., S. 4, 1790, pp. 1-17). I have been unable to ascertain in which of his publications he describes and names the cave-bear. [93] _Specimen archæologia telluris terrarumque imprimis Hannoveranæ_, pts. i., ii. _Cum 4 tabl. aen. 4 maj._ Gottingæ, 1803. [94] Faujas Saint-Fond wrote articles on fossil bones (1794); on fossil plants both of France (1803) and of Monte Bolca (1820); on a fish from Nanterre (1802) and a fossil turtle (1803); on two species of fossil ox, whose skulls were found in Germany, France, and England (1803), and on an elephant's tusk found in the volcanic tufa of Darbres (1803); on the fossil shells of Mayence (1806); and on a new genus (_Clotho_) of bivalve shells. [95] _Sur les ossemens qui se trouvent dans le gyps de Montmartre_ (_Bulletin des sciences pour la Société philomatique_, tomes 1, 2, 1798, pp. 154-155). [96] The following account is translated from the fourth edition of the _Ossemens fossiles_, vol. 1., 1834, also the sixth edition of the _Discours_, separately published in 1830. It does not differ materially from the first edition of the _Essay on the Theory of the Earth_, translated by Jameson, and republished in New York, with additions by Samuel L. Mitchell, in 1818. [97] In the first edition of the _Théorie_ he says fifteen years, writing in 1812. In the later edition he changed the number of years to thirty. [98] De Blainville is inclined to make light of Cuvier's law and of his assumptions; and in his somewhat cynical, depreciatory way, says: "Thus for the thirty years during which appeared the works of M. G. Cuvier on fossil bones, under the most favorable circumstances, in a kind of renascence of the science of organization of animals, then almost effaced in France, aided by the richest osteological collections which then existed in Europe, M. G. Cuvier passed an active and a comparatively long life, in a region abounding in fossil bones, without having established any other principle in osteology than a witticism which he had been unable for a moment to take seriously himself, because he had not yet investigated or sufficiently studied the science of organization, which I even doubt, to speak frankly, if he ever did. Otherwise, he would himself soon have perceived the falsity of his assertion that a single facet of a bone was sufficient to reconstruct a skeleton from the observation that everything is harmoniously correlated in an animal. It is a great thing if the memory, aided by a strong imagination, can thus pass from a bone to the entire skeleton, even in an animal well known and studied even to satiety; but for an unknown animal, there is no one except a man but slightly acquainted with the anatomy of animals who could pretend to do it. It is not true anatomists like Hunter, Camper, Pallas, Vicq-d'Azyr, Blumenbach, Soemmering, and Meckel who would be so presuming, and M. G. Cuvier would have been himself much embarrassed if he had been taken at his word, and besides it is this assertion which will remain formulated in the mouths of the ignorant, and which has already made many persons believe that it is possible to answer the most difficult and often insoluble problems in palæontology, without having made any preliminary study, with the aid of dividers, and, on the other hand, discouraging the Blumenbachs and Soemmerings from giving their attention to this kind of work." Huxley has, _inter alia_, put the case in a somewhat similar way, to show that the law should at least be applied with much caution to unknown forms: "Cuvier, in the _Discours sur les Révolutions de la Surface du Globe_, strangely credits himself, and has ever since been credited by others, with the invention of a new method of palæontological research. But if you will turn to the _Recherches sur les Ossemens fossiles_, and watch Cuvier not speculating, but working, you will find that his method is neither more nor less than that of Steno. If he was able to make his famous prophecy from the jaw which lay upon the surface of a block of stone to the pelvis which lay hidden in it, it was not because either he or any one else knew, or knows, why a certain form of jaw is, as a rule, constantly accompanied by the presence of marsupial bones, but simply because experience has shown that these two structures are coördinated" (_Science and Hebrew Tradition. Rise and Progress of Paleontology_ 1881, p. 23). [99] _History and Methods of Paleontological Discovery_ (1879). [100] The following statement of Cuvier's views is taken from Jameson's translation of the first _Essay on the Theory of the Earth_, "which formed the introduction to his _Recherches sur les Ossemens fossiles_," the first edition of which appeared in 1812, or ten years after the publication of the _Hydrogéologie_. The original I have not seen, but I have compared Jameson's translation with the sixth edition of the _Discours_ (1820). [101] Cuvier, in speaking of these revolutions, "which have changed the surface of our earth," correctly reasons that they must have excited a more powerful action upon terrestrial quadrupeds than upon marine animals. "As these revolutions," he says, "have consisted chiefly in changes of the bed of the sea, and as the waters must have destroyed all the quadrupeds which they reached if their irruption over the land was general, they must have destroyed the entire class, or, if confined only to certain continents at one time, they must have destroyed at least all the species inhabiting these continents, without having the same effect upon the marine animals. On the other hand, millions of aquatic animals may have been left quite dry, or buried in newly formed strata or thrown violently on the coasts, while their races may have been still preserved in more peaceful parts of the sea, whence they might again propagate and spread after the agitation of the water had ceased." [102] _Discours_, etc. Sixth edition. [103] Felix Bernard, _The Principles of Paleontology_, Paris, 1895, translated by C. E. Brooks, edited by J. M. Clark, from 14th Annual Report New York State Geologist, 1895, pp. 127-217 (p. 16). Bernard gives no reference to the work in which Schlotheim expressed this opinion. E. v. Schlotheim's first work, _Flora der Vorwelt_, appeared in 1804, entitled _Beschreibung merkwürdiger Kraüterabdrücke und Pflanzenversteinerungen. Ein Beytrag zur Flora der Vorvelt._ I Abtheil. Mit 14 Kpfrn. 4^o. Gotha, 1804. A later work was _Beyträge zur Naturgeschichte der Versteinerungen in geognostischer Hinsicht_ (_Denkschrift d. k. Academie d. Wissenschaften zu München für den Jahren 1816 und 1817_. 8 Taf. München, 1819). He was followed in Germany by Sternberg (_Versuch einer geognostischbotanischen Darstellung der Flora der Vorvelt._ 1-8. 1811. Leipzig, 1820-38); and in France by A. T. Brongniart, 1801-1876 (_Histoire des Végétaux fossiles_, 1828). These were the pioneers in palæophytology. [104] Bernard's _History and Methods of Paleontological Discovery_ (1879), p. 23. [105] In his valuable and comprehensive _Geschichte der Geologie und Paläontologie_ (1899), Prof. K. von Zittel, while referring to Lamarck's works on the tertiary shells of Paris and his _Animaux sans Vertèbres_, also giving a just and full account of his life, practically gives him the credit of being one of the founders of invertebrate palæontology. He speaks of him as "the reformer and founder of scientific conchology," and states that "he defined with wonderful acuteness the numerous genera and species of invertebrate animals, and created thereby for the ten years following an authoritative foundation." Zittel, however, does not mention the _Hydrogéologie_. Probably so rare a book was overlooked by the eminent German palæontologist. [106] _History and Methods of Paleontological Discovery_ (1879), p. 23. CHAPTER X LAMARCK'S OPINIONS ON GENERAL PHYSIOLOGY AND BIOLOGY Lamarck died before the rise of the sciences of morphology, embryology, and cytology. As to palæontology, which he aided in founding, he had but the slightest idea of the geological succession of life-forms, and not an inkling of the biogenetic law or recapitulation theory. Little did he know or foresee that the main and strongest support of his own theory was to be this same science of the extinct forms of life. Yet it is a matter of interest to know what were his views or opinions on the nature of life; whether he made any suggestions bearing on the doctrine of the unity of nature; whether he was a vitalist or not; and whether he was a follower of Haller and of Bonnet,[107] as was Cuvier, or pronounced in favor of epigenesis. We know that he was a firm believer in spontaneous generation, and that he conceived that it took place not only in the origination of his primeval germs or _ébauches_, but at all later periods down to the present day. Yet Lamarck accepted Harvey's doctrine, published in 1651, that all living beings arose from germs or eggs.[108] He must have known of Spallanzani's experiments, published in 1776, even if he had not read the writings of Treviranus (1802-1805), both of whom had experimentally disproved the theory of the spontaneous generation of animalcules in putrid infusions, showing that the lowest organisms develop only from germs. The eighteenth century, though one of great intellectual activity, was, however, as regards cosmology, geology, general physiology or biology, a period of groping in the dim twilight, when the whole truth or even a part of it was beyond the reach of the greatest geniuses, and they could only seize on half-truths. Lamarck, both a practical botanist, systematic zoölogist, and synthetic philosopher, had done his best work before the rise of the experimental and inductive methods, when direct observation and experiments had begun to take the place of vague _à priori_ thinking and reasoning, so that he labored under a disadvantage due largely to the age in which he lived. Only the closing years of the century witnessed the rise of the experimental methods in physics and chemistry, owing to the brilliant work of Priestley and of Lavoisier. The foundations of general physiology had been laid by Haller,[109] those of embryology to a partial extent by Wolff,[110] Von Baer's work not appearing until 1829, the year in which Lamarck died. _Spontaneous Generation._--Lamarck's views on spontaneous generation are stated in his _Recherches sur l'Organisation des Corps vivans_ (1802). He begins by referring to his statement in a previous work[111] that life may be suspended for a time and then go on again. "Here I would remark it (life) can be produced (_préparée_) both by an organic act and by nature herself, without any act of this kind, in such a way that certain bodies without possessing life can be prepared to receive it, by an impression _which indicates in these bodies the first traces of organization_." We will not enter upon an exposition of his views on the nature of sexual generation and of fecundation, the character of his _vapeur subtile_ (_aura vitalis_) which he supposes to take an active part in the act of fertilization, because the notion is quite as objectionable as that of the vital force which he rejects. He goes on to say, however, that we cannot penetrate farther into the wonderful mystery of fecundation, but the opinions he expresses lead to the view that "nature herself imitates her procedures in fecundation in another state of things, without having need of the union or of the products of any preëxistent organization." He proceeds to observe that in the places where his _aura vitalis_, or subtle fluid, is very abundant, as in hot climates or in heated periods, and especially in humid places, life seems to originate and to multiply itself everywhere and with a singular rapidity. "In this high temperature the higher animals and mankind develop and mature more rapidly, and diseases run their courses more swiftly; while on the other hand these conditions are more favorable to the simpler forms of life, for the reason that in them the orgasm and irritability are entirely dependent on external influences, and all plants are in the same case, because heat, moisture, and light complete the conditions necessary to their existence. "Because heat is so advantageous to the simplest animals, let us examine whether there is not occasion for believing that it can itself form, with the concourse of favorable circumstances, the first germs of animal life. "_Nature necessarily forms generations, spontaneous or direct, at the extremity of each organic kingdom or where the simplest organic bodies occur._" This proposition, he allows, is so far removed from the view generally held, that it will be for a long time, and perhaps always, regarded as one of the errors of the human mind. "I do not," he adds, "ask any one to accord it the least confidence on my word alone. But as surely it will happen, sooner or later, that men on the one hand independent of prejudices even the most widespread, and on the other profound observers of nature, may have a glimpse of this truth, I am very content that we should know that it is of the number of those views which, in spite of the prejudices of my age, I have thought it well to accept." "Why," he asks, "should not heat and electricity act on certain matters under favorable conditions and circumstances?" He quotes Lavoisier as saying (_Chémie_, i., p. 202) "that God in creating light had spread over the world the principle of organization of feeling and of thought"; and Lamarck suggests that heat, "this mother of generation, this material soul of organized bodies," may be the chief one of the means which nature directly employs to produce in the appropriate kind of matter an act of arrangement of parts, of a primitive germ of organization, and consequently of vitalization analogous to sexual fecundation. "Not only the direct formation of the simplest living beings could have taken place, as I shall attempt to demonstrate, but the following considerations prove that it is necessary that such germ-formations should be effected and be repeated under favorable conditions, without which the state of things which we observe could neither exist nor subsist." His argument is that in the lower polyps (the Protozoa) there is no sexual reproduction, no eggs. But they perish (as he strangely thought, without apparently attempting to verify his belief) in the winter. How, he asks, can they reappear? Is it not more likely that these simple organisms are themselves regenerated? After much verbiage and repetition, he concludes: "We may conceive that the simplest organisms can arise from a minute mass of substances which possess the following conditions--namely, which will have solid parts in a state nearest the fluid conditions, consequently having the greatest suppleness and only sufficient consistence to be susceptible of constituting the parts contained in it. Such is the condition of the most gelatinous organized bodies. "Through such a mass of substances the subtile and expansive fluids spread, and, always in motion in the milieu environing it, unceasingly penetrate it and likewise dissipate it, arranging while traversing this mass the internal disposition of its parts, and rendering it suitable to continually absorb and to exhale the other environing fluids which are able to penetrate into its interior, and which are susceptible of being contained. "These other fluids, which are water charged with dissolved (_dissous_) gas, or with other tenuous substances, the atmospheric air, which contains water, etc., I call containable fluids, to distinguish them from subtile fluids, such as caloric, electricity, etc., which no known bodies are believed to contain. "The containable fluids absorbed by the small gelatinous mass in question remain almost motionless in its different parts, because the non-containable subtile fluids which always penetrate there do not permit it. "In this way the uncontainable fluids at first mark out the first traces of the simplest organization, and consequently the containable fluids by their movements and their other influences develop it, and with time and all the favorable circumstances complete it." This is certainly a sufficiently vague and unsatisfactory theory of spontaneous generation. This sort of guess-work and hypothetical reasoning is not entirely confined to Lamarck's time. Have we not, even a century later, examples among some of our biologists, and very eminent ones, of whole volumes of _à priori_ theorizing and reasoning, with scarcely a single new fact to serve as a foundation? And yet this is an age of laboratories, of experimentations and of trained observers. The best of us indulge in far-fetched hypotheses, such as pangenesis, panmixia, the existence of determinants, and if this be so should we not excuse Lamarck, who gave so many years to close observation in systematic botany and zoölogy, for his flights into the empyrean of subtle fluids, containable and uncontainable, and for his invocation of an _aura vitalis_, at a time when the world of demonstrated facts in modern biology was undiscovered and its existence unsuspected? _The Preëxistence of Germs and the Encasement Theory._--Lamarck did not believe in Bonnet's idea of the "preëxistence of germs." He asks whether there is any foundation for the notion that germs "successively develop in generations, _i.e._ in the multiplication of individuals for the preservation of species," and says: "I am not inclined to believe it if this preëxistence is taken in a general sense; but in limiting it to individuals in which the unfertilized embryos or germs are formed before generation. I then believe that it has some foundation.--They say with good reason," he adds, "that every living being originates from an egg.... But the eggs being the envelope of every kind of germ, they preëxist in the individuals which produce them, before fertilization has vivified them. The seeds of plants (which are vegetable eggs) actually exist in the ovaries of flowers before the fertilization of these ovaries."[112] From whom did he get this idea that seeds or eggs are envelopes of all sorts of germs? It is not the "evolution" of a single germ, as, for example, an excessively minute but complete chick in the hen's egg, in the sense held by Bonnet. Who it was he does not mention. He evidently, however, had the Swiss biologist in mind, who held that all living things proceed from preëxisting germs.[113] Whatever may have been his views as to the germs in the egg before fertilization, we take it that he believed in the epigenetic development of the plant or animal after the seed or egg was once fertilized.[114] Lamarck did not adopt the encasement theory of Swammerdam and of Heller. We find nothing in Lamarck's writings opposed to epigenesis. The following passage, which bears on this subject, is translated from his _Mémoires de Physique_ (p. 250), where he contrasts the growth of organic bodies with that of minerals. "The body of this living being not having been formed by _juxtaposition_, as most mineral substances, that is to say, by the external and successive apposition of particles aggregated _en masse_ by attraction, but essentially formed by generation, in its principle, it has then grown by intussusception--namely, by the introduction, the transportation, and the internal apposition of molecules borne along and deposited between its parts; whence have resulted the successive developments of parts which compose the body of this living individual, and from which afterwards also result the repairs which preserve it during a limited time." Here, as elsewhere in his various works, Lamarck brings out the fact, for the first time stated, that all material things are either non-living or mineral, inorganic; or living, organic. A favorite phrase with him is living bodies, or, as we should say, organisms. He also is the first one to show that minerals increase by juxtaposition, while organisms grow by intussusception. No one would look in his writings for an idea or suggestion of the principle of differentiation of parts or organs as we now understand it, or for the idea of the physiological division of labor; these were reserved for the later periods of embryology and morphology. _Origin of the First Vital Function._--We will now return to the germ. After it had begun spontaneous existence, Lamarck proceeds to say: "Before the containable fluids absorbed by the small, jelly-like mass in question have been expelled by the new portions of the same fluids which reach there, they can then deposit certain of the contained fluids they carry along, and the movements of the contained fluids may apply these substances to the containing parts of the newly organized microscopic being. In this way originates the first of the vital functions which becomes established in the simplest organism, _i.e._, nutrition. The environing containable fluids are, then, for the living body of very great simplicity, a veritable chyle entirely prepared by nature. "Mutilation cannot operate without gradually increasing the consistence of the parts contained within the minute new organism and without extending its dimensions. Hence soon arose the second of the vital functions, _growth or internal development_." _First Faculty of Animal Nature._--Then gradually as the continuity of this state of things within the same minute living mass in question increases the consistence of its parts enclosed within and extends its dimensions, a vital orgasm, at first very feeble, but becoming progressively more intense, is formed in these enclosed parts and renders them susceptible of _reaction_ against the slight impression of the fluids in motion which they contain, and at the same time renders them capable of contraction and of distention. Hence the origin of _animal irritability_ and the basis of feeling, which is developed wherever a nervous fluid, susceptible of locating the effects in one of several special centres, can be formed. "Scarcely will the living corpuscle, newly animalized, have received any increase in consistence and in dimensions of the parts contained, when, as the result of the organic movement which it enjoys, it will be subjected to successive changes and losses of its substance. "It will then be obliged to take nourishment not only to obtain any development whatever, but also to preserve its individual existence, because it is necessary that it repair its losses under penalty of its destruction. "But as the individual in question has not yet any special organ for nutrition, it therefore absorbs by the pores of its internal surface the substance adapted for its nourishment. Thus the first mode of taking food in a living body so simple can be no other than by absorption or a sort of suction, which is accomplished by the pores of its outer surface. "This is not all; up to the present time the animalized corpuscle we are considering is still only a primitive animalcule because it as yet has no special organ. Let us see then how nature will come to furnish it with any primitive special organ, and what will be the organ that nature will form before any others, and which in the simplest animal is the only one constantly found; this is the alimentary canal, the principal organ of digestion common to all except colpodes, vibrios, proteus (amoeba), volvoces, monads, etc. "This digestive canal is," he says--proceeding with his _à priori_ morphology--"a little different from that of this day, produced by contractions of the body, which are stronger in one part of the body than in another, until a little crease is produced on the surface of the body. This furrow or crease will receive the food. Insensibly this little furrow by the habit of being filled, and by the so frequent use of its pores, will gradually increase in depth; it will soon assume the form of a pouch or of a tubular cavity with porous walls, a blind sac, or with but a single opening. Behold the primitive alimentary canal created by nature, the simplest organ of digestion." In like _à priori_ manner he describes the creation of the faculty of reproduction. The next organ, he says, is that of reproduction due to the regenerative faculty. He describes fission and budding. Finally (p. 122) he says: "Indeed, we perceive that if the first germs of living bodies are all formed in one day in such great abundance and facility under favorable circumstances, they ought to be, nevertheless, by reason of the antiquity of the causes which make them exist, the most ancient organisms in nature." In 1794 he rejected the view once held of a continuous chain of being, the _échelle des êtres_ suggested by Locke and by Leibnitz, and more fully elaborated by Bonnet, from the inorganic to the organic worlds, from minerals to plants, from plants to polyps (our Infusoria), polyps to worms, and so on to the higher animals. He, on the contrary, affirms that nature makes leaps, that there is a wide gap between minerals and living bodies, that everything is not gradated and shaded into each other. One reason for this was possibly his strange view, expressed in 1794, that all brute bodies and inorganic matters, even granite, were not formed at the same epoch but at different times, and were derived from organisms.[115] The mystical doctrine of a vital force was rife in Lamarck's time. The chief starting point of the doctrine was due to Haller, and, as Verworn states, it is a doctrine which has confused all physiology down to the middle of the present century, and even now emerges again here and there in varied form.[116] Lamarck was not a vitalist. Life, he says,[117] is usually supposed to be a particular being or entity; a sort of principle whose nature is unknown, and which possesses living bodies. This notion he denies as absurd, saying that life is a very natural phenomenon, a physical fact; in truth a little complicated in its principles, but not in any sense a particular or special being or entity. He then defines life in the following words: "Life is an order and a state of things in the parts of every body possessing it, which permits or renders possible in it the execution of organic movement, and which, so long as it exists, is effectively opposed to death. Derange this order and this state of things to the point of preventing the execution of organic movement, or the possibility of its reëstablishment, then you cause death." Afterwards, in the _Philosophie zoologique_, he modifies this definition, which reads thus: "Life, in the parts of a body which possesses it, is an order and a state of things which permit organic movements; and these movements, which constitute active life, result from the action of a stimulating cause which excites them."[118] For the science of all living bodies Lamarck proposed the word "Biology," which is so convenient a term at the present day. The word first appears in the preface to the _Hydrogéologie_, published in 1802. It is worthy of note that in the same year the same word was proposed for the same science by G. R. Treviranus as the title of a work, _Biologie, der Philosophie der lebenden Natur_, published in 1802-1805 (vols. i.-vi., 1802-1822), the first volume appearing in 1802. In the second part of the _Philosophie zoologique_ he considers the physical causes of life, and in the introduction he defines nature as the _ensemble_ of objects which comprise: (1) All existing physical bodies; (2) the general and special laws which regulate the changes of condition and situation of these bodies; (3) finally, the movement everywhere going on among them resulting in the wonderful order of things in nature. To regard nature as eternal, and consequently as having existed from all time, is baseless and unreasonable. He prefers to think that nature is only a result, "whence, I suppose, and am glad to admit, a first cause, in a word, a supreme power which has given existence to nature, which has made it as a whole what it is." As to the source of life in bodies endowed with it, he considers it a problem more difficult than to determine the course of the stars in space, or the size, masses, and movements of the planets belonging to our solar system; but, however formidable the problem, the difficulties are not insurmountable, as the phenomena are purely physical--_i.e._, essentially resulting from acts of organization. After defining life, in the third chapter (beginning vol. ii.) he treats of the exciting cause of organic movements. This exciting cause is foreign to the body which it vivifies, and does not perish, like the latter. "This cause resides in invisible, subtile, expansive, ever-active fluids which penetrate or are incessantly developed in the bodies which they animate." These subtile fluids we should in these days regard as the physico-chemical agents, such as heat, light, electricity. What he says in the next two chapters as to the "orgasme" and irritability excited by the before-mentioned exciting cause may be regarded as a crude foreshadowing of the primary properties of protoplasm, now regarded as the physical basis of life--_i.e._, contractility, irritability, and metabolism. In Chapter VI. Lamarck discusses direct or spontaneous generation in the same way as in 1802. In the following paragraph we have foreshadowed the characteristic qualities of the primeval protoplasmic matter fitted to receive the first traces of organization and life: "Every mass of substance homogeneous in appearance, of a gelatinous or mucilaginous consistence, whose parts, coherent among themselves, will be in the state nearest fluidity, but will have only a consistence sufficient to constitute containing parts, will be the body most fitted to receive the first traces of organization and life." In the third part of the _Philosophie zoologique_ Lamarck considers the physical causes of feeling--_i.e._, those which form the productive force of actions, and those giving rise to intelligent acts. After describing the nervous system and its functions, he discusses the nervous fluid. His physiological views are based on those of Richerand's _Physiologie_, which he at times quotes. Lamarck's thoughts on the nature of the nervous fluid (_Recherches sur le fluide nerveux_) are curious and illustrative of the gropings after the truth of his age. He claims that the supposed nervous fluid has much analogy to the electric, that it is the _feu éthéré_ "animalized by the circumstances under which it occurs." In his _Recherches sur l'organisation des corps vivans_ (1802) he states that, as the result of changes continually undergone by the principal fluids of an animal, there is continually set free in a state of _feu fixé_ a special fluid, which at the instant of its disengagement occurs in the expansive state of the caloric, then becomes gradually rarefied, and insensibly arrives at the state of an extremely subtile fluid which then passes along the smallest nervous ramifications in the substance of the nerve, which is a very good conductor for it. On its side the brain sends back the subtile fluid in question along the nerves to the different organs. In the same work (1802) Lamarck defines thought as a physical act taking place in the brain. "This act of thinking gives rise to different displacements of the subtile nervous fluid and to different accumulations of this fluid in the parts of the brain where the ideas have been traced." There result from the flow of the fluid on the conserved impressions of ideas, special movements which portions of this fluid acquire with each impression, which give rise to compounds by their union producing new impressions on the delicate organ which receives them, and which constitute abstract ideas of all kinds, also the different acts of thought. All the acts which constitute thought are the comparisons of ideas, both simple and complex, and the results of these comparisons are judgments. He then discusses the influence of the nervous fluid on the muscles, and also its influence considered as the cause of feeling (_sentiment_). Finally he concludes that _feu fixé_, caloric, the nervous fluid, and the electric fluid "are only one and the same substance occurring in different states." FOOTNOTES: [107] Charles Bonnet (1720-1793), a Swiss naturalist, is famous for his work on Aphides and their parthenogenetic generation, on the mode of reproduction in the Polyzoa, and on the respiration of insects. After the age of thirty-four, when his eyesight became impaired, he began his premature speculations, which did not add to his reputation. Judging, however, by an extract from his writings by D'Archiac (_Introduction à l'Étude de la Paléontologie stratigraphique_, ii., p. 49), he had sound ideas on the theory of descent, claiming that "la diversité et la multitude des conjunctions, peut-être même la diversité des climats et des nourritures, ont donné naissance à de nouvelles espèces ou à des individus intermédiaires" (_Oeuvres d'Hist. nat. et de Philosophie_, in-8vo, p. 230, 1779). [108] See his remark: "_On a dit avec raison que tout ce qui a vie provient d'un auf_" (_Mémoires de Physique_, etc., 1797, p. 272). He appears, however, to have made the simplest organisms exceptions to this doctrine. [109] _Elementa physiologiae corporis humani_, iv. Lausanne, 1762. [110] _Theoria generationis_, 1774. [111] _Mémoires de Physique_, (1797), p. 250. [112] _Mémoires de Physique_, etc. (1797), p. 272. [113] Huxley's "Evolution in Biology" (_Darwiniana_, p. 192), where be quotes from Bonnet's statements, which "bear no small resemblance to what is understood by evolution at the present day." [114] Buffon did not accept Bonnet's theory of preëxistent germs, but he assumed the existence of "_germes accumulés_" which reproduced parts or organs, and for the production of organisms he imagined "_molécules organiques_." Réaumur had previously (1712) conjectured that there were "_germes cachés et accumulés_" to account for the regeneration of the limbs of the crayfish. The ideas of Bonnet on germs are stated in his _Mémoires sur les Salamandres_ (1777-78-80) and in his _Considérations sur les corps organisés_ (1762.) [115] _Mémoires de Physique_, etc., pp. 318, 319, 324-359. Yet the idea of a sort of continuity between the inorganic and the organic world is expressed by Verworn. [116] _General Physiology_ (English trans., 1899, p. 17). In France vitalism was founded by Bordeu (1722-1766), developed further by Barthez (1734-1806) and Chaussier (1746-1828), and formulated most distinctly by Louis Dumas (1765-1813). Later vitalists gave it a thoroughly mystical aspect, distinguishing several varieties, such as the _nisus formativus_ or formative effort, to explain the forms of organisms, accounting for the fact that from the egg of a bird, a bird and no other species always develops (_l. c._, p. 18). [117] _Recherches sur l'organisation des corps vivans_ (1802), p. 70. The same view was expressed in _Mémoires de physique_ (1797), pp. 254-257, 386. [118] Here might be quoted for comparison other famous definitions of life: "Life is the sum of the functions by which death is resisted."--Bichat. "Life is the result of organization."--(?) "Life is the principle of individuation."--Coleridge ex. Schelling. "Life is the twofold internal movement of composition and decomposition, at once general and continuous."--De Blainville, who wisely added that there are "two fundamental and correlative conditions inseparable from the living being--an organism and a medium." "Life is the continuous adjustment of internal relations to external relations."--Herbert Spencer. CHAPTER XI LAMARCK AS A BOTANIST During the century preceding the time of Lamarck, botany had not flourished in France with the vigor shown in other countries. Lamarck himself frankly stated in his address to the Committee of Public Instruction of the National Convention that the study of plants had been for a century neglected by Frenchmen, and that the great progress which it had made during this time was almost entirely due to foreigners. "I am free to say that since the distinguished Tournefort the French have remained to some extent inactive in this direction; they have produced almost nothing, unless we except some fragmentary mediocre or unimportant works. On the other hand, Linné in Sweden, Dilwillen in England, Haller in Switzerland, Jacquin in Austria, etc., have immortalized themselves by their own works, vastly extending the limit of our knowledge in this interesting part of natural history." What led young Lamarck to take up botanical studies, his botanical rambles about Paris, and his longer journeys in different parts of France and in other countries, his six years of unremitting labor on his _Flore Française_, and the immediate fame it brought him, culminating in his election as a member of the French Academy, have been already recounted. Lamarck was thirty-four when his _Flore Française_ appeared. It was not preceded, as in the case of most botanical works, by any preliminary papers containing descriptions of new or unknown species, and the three stout octavo volumes appeared together at the same date. The first volume opens with a report on the work made by MM. Duhamel and Guettard. Then follows the _Discours Préliminaire_, comprising over a hundred pages, while the main body of the work opens with the _Principes Élémentaires de Botanique_, occupying 223 pages. The work was a general elementary botany and written in French. Before this time botanists had departed from the artificial system of Linné, though it was convenient for amateurs in naming their plants. Jussieu had proposed his system of natural families, founded on a scientific basis, but naturally more difficult for the use of beginners. To obviate the matter Lamarck conceived and proposed the dichotomic method for the easy determination of species. No new species were described, and the work, written in the vernacular, was simply a guide to the indigenous plants of France, beginning with the cryptogams and ending with the flowering plants. A second edition appeared in 1780, and a third, edited and remodelled by A. P. De Candolle, and forming six volumes, appeared in 1805-1815. This was until within a comparatively few years the standard French botany. Soon after the publication of his _Flore Française_ he projected two other works which gave him a still higher position among botanists. His _Dictionnaire de Botanique_ was published in 1783-1817, forming eight volumes and five supplementary ones. The first two and part of the third volume were written by Lamarck, the remainder by other botanists, who completed it after Lamarck had abandoned botanical studies and taken up his zoölogical work. His second great undertaking was _L'Illustration des Genres_ (1791-1800), with a supplement by Poiret (1823). Cuvier speaks thus of these works: "_L'Illustration des Genres_ is a work especially fitted to enable one to acquire readily an almost complete idea of this beautiful science. The precision of the descriptions and of the definitions of Linnæus is maintained, as in the institutions of Tournefort, with figures adapted to give body to these abstractions, and to appeal both to the eye and to the mind, and not only are the flowers and fruits represented, but often the entire plant. More than two thousand genera are thus made available for study in a thousand plates in quarto, and at the same time the abridged characters of a vast number of species are given. "The _Dictionnaire_ contains more details of the history with careful descriptions, critical researches on their synonymy, and many interesting observations on their uses or on special points of their organizations. The matter is not all original in either of the works, far from it, but the choice of figures is skilfully made, the descriptions are drawn from the best authors, and there are a large number which relate to species and also some genera previously unknown." Lamarck himself says that after the publication of his _Flore Française_, his zeal for work increasing, and after travelling by order of the government in different parts of Europe, he undertook on a vast scale a general work on botany. "This work comprised two distinct features. In the first (_Le Dictionnaire_), which made a part of the new encyclopedia, the citizen Lamarck treats of philosophical botany, also giving the complete description of all the genera and species known. An immense work from the labor it cost, and truly original in its execution.... The second treatise, entitled _Illustration des Genres_, presents in the order of the sexual system the figures and the details of all the genera known in botany, and with a concise exposition of the generic characters and of the species known. This work, unique of its kind, already contains six hundred plates executed by the best artists, and will comprise nine hundred. Also for more than ten years the citizen Lamarck has employed in Paris a great number of artists. Moreover, he has kept running three separate presses for different works, all relating to natural history." Cuvier in his _Éloge_ also adds: "It is astonishing that M. de Lamarck, who hitherto had been studying botany as an amateur, was able so rapidly to qualify himself to produce so extensive a work, in which the rarest plants were described. It is because, from the moment he undertook it, with all the enthusiasm of his nature, he collected them from the gardens and examined them in all the available herbaria; passing the days at the houses of the botanists he knew, but chiefly at the home of M. de Jussieu, in that home where for more than a century a scientific hospitality welcomed with equal kindness every one who was interested in the delightful study of botany. When any one reached Paris with plants he might be sure that the first one who should visit him would be M. de Lamarck; this eager interest was the means of his receiving one of the most valuable presents he could have desired. The celebrated traveller Sonnerat, having returned in 1781 for the second time from the Indies, with very rich collections of natural history, imagined that every one who cultivated this science would flock to him; it was not at Pondichéry or in the Moluccas that he had conceived an idea of the vortex which too often in this capital draws the savants as well as men of the world; no one came but M. de Lamarck, and Sonnerat, in his chagrin, gave him the magnificent collection of plants which he had brought. He profited also by that of Commerson, and by those which had been accumulated by M. de Jussieu, and which were generously opened to him." These works were evidently planned and carried out on a broad and comprehensive scale, with originality of treatment, and they were most useful and widely used. Lamarck's original special botanical papers were numerous. They were mostly descriptive of new species and genera, but some were much broader in scope and were published over a period of ten years, from 1784 to 1794, and appeared in the _Journal d'Histoire naturelle_, which he founded, and in the _Mémoires_ of the Academy of Sciences. He discussed the shape or aspect of the plants characteristic of certain countries, while his last botanical effort was on the sensibility of plants (1798). Although not in the front rank of botanists, compared with Linné, Jussieu, De Candolle, and others, yet during the twenty-six years of his botanical career it may safely be said that Lamarck gave an immense impetus to botany in France, and fully earned the title of "the French Linné." Lamarck not only described a number of genera and species of plants, but he attempted a general classification, as Cleland states: "In 1785 (_Hist. de l'Acad._) he evinced his appreciation of the necessity of natural orders in botany by an attempt at the classification of plants, interesting though crude, and falling immeasurably short of the system which grew in the hands of his intimate friend Jussieu."--_Encyc. Brit._, Art. LAMARCK. A genus of tropical plants of the group _Solanaceæ_ was named _Markea_ by Richard, in honor of Lamarck, but changed by Persoon and Poiret to _Lamarckea_. The name _Lamarckia_ of Moench and Koeler was proposed for a genus of grasses; it is now _Chrysurus_. Lamarck's success as a botanist led to more or less intimate relations with Buffon. But it appears that the good-will of this great naturalist and courtier for the rising botanist was not wholly disinterested. Lamarck owed the humble and poorly paid position of keeper of the herbarium to Buffon. Bourguin adds, however: "_Mais il les dut moins à ses mérites qu'aux petits passions de la science officielle._ The illustrious Buffon, who was at the same time a very great lord at court, was jealous of Linné. He could not endure having any one compare his brilliant and eloquent word-pictures of animals with the cold and methodical descriptions of the celebrated Swedish naturalist. So he attempted to combat him in another field--botany. For this reason he encouraged and pushed Lamarck into notice, who, as the popularizer of the system of classification into natural families, seemed to him to oppose the development of the arrangement of Linné." Lamarck's style was never a highly finished one, and his incipient essays seemed faulty to Buffon, who took so much pains to write all his works in elegant and pure French. So he begged the Abbé Haüy to review the literary form of Lamarck's works. Here it might be said that Lamarck's is the philosophic style; often animated, clear, and pure, it at times, however, becomes prolix and tedious, owing to occasional repetition. But after all it can easily be understood that the discipline of his botanical studies, the friendship manifested for him by Buffon, then so influential and popular, the relations Lamarck had with Jussieu, Haüy, and the zoölogists of the Jardin du Roi, were all important factors in Lamarck's success in life, a success not without terrible drawbacks, and to the full fruition of which he did not in his own life attain. CHAPTER XII LAMARCK THE ZOÖLOGIST Although there has been and still may be a difference of opinion as to the value and permanency of Lamarck's theoretical views, there has never been any lack of appreciation of his labors as a systematic zoölogist. He was undoubtedly the greatest zoölogist of his time. Lamarck is the one dominant personage who in the domain of zoölogy filled the interval between Linné and Cuvier, and in acuteness and sound judgment he at times surpassed Cuvier. His was the master mind of the period of systematic zoölogy, which began with Linné--the period which, in the history of zoölogy, preceded that of comparative anatomy and morphology. After Aristotle, no epoch-making zoölogist arose until Linné was born. In England Linné was preceded by Ray, but binomial nomenclature and the first genuine attempt at the classification of animals dates back to the _Systema Naturæ_ of Linné, the tenth edition of which appeared in 1758. [Illustration: PORTRAIT OF LAMARCK] The contemporaries of Lamarck in biological science, in the eighteenth century, were Camper (1722-89), Spallanzani (1729-99), Wolff (1733-94), Hunter (1728-93), Bichat (1771-1802), and Vicq d'Azyr (1748-94). These were all anatomists and physiologists, the last-named being the first to propose and use the term "comparative anatomy," while Bichat was the founder of histology and pathological anatomy. There was in fact no prominent systematic zoölogist in the interval between Linné and Lamarck. In France there were only two zoölogists of prominence when Lamarck assumed his duties at the Museum. These were Bruguière the conchologist and Olivier the entomologist. In Germany Hermann was the leading systematic zoölogist. We would not forget the labors of the great German anatomist and physiologist Blumenbach, who was also the founder of anthropology; nor the German anatomists Tiedemann, Bojanus, and Carus; nor the embryologist Döllinger. But Lamarck's method and point of view were of a new order--he was much more than a mere systematist. His work in systematic zoölogy, unlike that of Linné, and especially of Cuvier, was that of a far higher grade. Lamarck, besides his rigid, analytical, thorough, and comprehensive work on the invertebrates, whereby he evolved order and system out of the chaotic mass of forms comprised in the Insects and Vermes of Linné, was animated with conceptions and theories to which his forerunners and contemporaries, Geoffroy St. Hilaire excepted, were entire strangers. His tabular view of the classes of the animal kingdom was to his mind a genealogical tree; his idea of the animal kingdom anticipated and was akin to that of our day. He compares the animal series to a tree with its numerous branches, rather than to a single chain of being. This series, as he expressly states, began with the monad and ended with man; it began with the simple and ended with the complex, or, as we should now say, it proceeded from the generalized or undifferentiated to the specialized and differentiated. He perceived that many forms had been subjected to what he calls degeneration, or, as we say, modification, and that the progress from the simple to the complex was by no means direct. Moreover, fossil animals were, according to his views, practically extinct species, and stood in the light of being the ancestors of the members of our existing fauna. In fact, his views, notwithstanding shortcomings and errors in classification naturally due to the limited knowledge of anatomy and development of his time, have been at the end of a century entirely confirmed--a striking testimony to his profound insight, sound judgment, and philosophic breadth. The reforms that he brought about in the classification of the invertebrate animals were direct and positive improvements, were adopted by Cuvier in his _Règne animal_, and have never been set aside. We owe to him the foundation and definition of the classes of Infusoria, Annelida, Arachnida, and Crustacea, the two latter groups being separated from the insects. He also showed the distinctness of echinoderms from polyps, thus anticipating Leuckart, who established the phylum of Coelenterata nearly half a century later. His special work was the classification of the great group of Mollusca, which he regarded as a class. When in our boyhood days we attempted to arrange our shells, we were taught to use the Lamarckian system, that of Linné having been discarded many years previous. The great reforms in the classification of shells are evidenced by the numerous manuals of conchology based on the works of Lamarck. We used to hear much of the Lamarckian genera of shells, and Lamarck was the first to perceive the necessity of breaking up into smaller categories the few genera of Linné, which now are regarded as families. He may be said to have had a wonderfully good eye for genera. All his generic divisions were at once accepted, since they were based on valid characters. Though not a comparative anatomist, he at once perceived the value of a knowledge of the internal structure of animals, and made effective use of the discoveries of Cuvier and of his predecessors--in fact, basing his system of classification on the organs of respiration, circulation, and the nervous system. He intimated that specific characters vary most, and that the peripheral parts of the body, as the shell, outer protective structures, the limbs, mouth-parts, antennæ, etc., are first affected by the causes which produce variation, while he distinctly states that it requires a longer time for variations to take place in the internal organs. On the latter he relied in defining his classes. One is curious to know how Lamarck viewed the question of species. This is discussed at length by him in his general essays, which are reproduced farther on in this biography, but his definition of what a species is far surpasses in breadth and terseness, and better satisfies the views now prevailing, than that of any other author. His definition of a species is as follows: "Every collection of similar individuals, perpetuated by generation in the same condition, so long as the circumstances of their situation do not change enough to produce variations in their habits, character, and form." Lamarck's rare skill, thoroughness, and acuteness as an observer, combined with great breadth of view, were also supplemented by the advantages arising from residence in Paris, and his connection with the Museum of Natural History. Paris was in the opening years of the nineteenth century the chief centre of biological science. France having convalesced from the intestinal disorders of the Revolution, and, as the result of her foreign wars, adding to her territory and power, had begun with the strength of a young giant to send out those splendid exploring expeditions which gathered in collections in natural history from all parts of the known or accessible world, and poured them, as it were, into the laps of the professors of the Jardin des Plantes. The shelves and cases of the galleries fairly groaned with the weight of the zoölogical riches which crowded them. From the year 1800 to 1832 the French government showed the greatest activity in sending out exploring expeditions to Egypt, Africa, and the tropics.[119] The zoölogists who explored Egypt were Geoffroy St. Hilaire and Savigny. Those who visited the East, the South Seas, the East Indian archipelago, and other regions were Bruguière, Olivier, Bory de St. Vincent, Péron, Lesueur, Quoy, Gaimard, Le Vaillant, Edoux, and Souleyet. The natural result was the enormous collections of the Jardin des Plantes, and consequently enlarged views regarding the number and distribution of species, and their relation to their environment. In Paris, about the time of Lamarck's death, flourished also Savigny, who published his immortal works on the morphology of arthropods and of ascidians; and Straus-Durckheim, whose splendidly illustrated volumes on the anatomy of the cockchafer and of the cat will never cease to be of value; and É. Geoffroy St. Hilaire, whose elaborate and classical works on vertebrate morphology, embryology, and comparative anatomy added so much to the prestige of French science. We may be sure that Lamarck did his own work without help from others, and gave full credit to those who, like Defrance or Bruguière, aided or immediately preceded him. He probably was lacking in executive force, or in the art which Cuvier knew so well to practise, of enlisting young men to do the drudgery or render material aid, and then, in some cases, neglecting to give them proper credit. The first memoir or paper published on a zoölogical subject by Lamarck was a modest one on shells, which appeared in 1792 in the _Journal d'Histoire naturelle_, the editors of which were Lamarck, Bruguière, Olivier, Haüy, and Pelletier. This paper was a review of an excellent memoir by Bruguière, who preceded Lamarck in the work of dismemberment of the Linnæan genera. His next paper was on four new species of Helix. To this _Journal_, of which only two volumes were published, Cuvier contributed his first paper--namely, on some new species of "Cloportes" (Oniscus, a genus of terrestrial crustacea or "pill-bugs"); this was followed by his second memoir on the anatomy of the limpet, his next article being descriptions of two species of flies from his collection of insects.[120] Seven years later Lamarck gave some account of the genera of cuttlefishes. His first general memoir was a prodromus of a new classification of shells (1799). Meanwhile Lamarck's knowledge of shells and corals was utilized by Cuvier in his _Tableau élémentaire_, published in 1798, who acknowledges in the preface that in the exposition of the genera of shells he has been powerfully seconded, while he indicated to him (Cuvier) a part of the subgenera of corals and alcyonarians, and adds, "I have received great aid from the examination of his collection." Also he acknowledges that he had been greatly aided (_puissamment secondé_) by Lamarck, who had even indicated the most of the subdivisions established in his _Tableau élémentaire_ for the insects (Blainville, _l. c._, p. 129), and he also accepted his genera of cuttlefishes. After this Lamarck judiciously refrained from publishing descriptions of new species, and other fragmentary labors, and for some ten years from the date of publication of his first zoölogical article reserved his strength and elaborated his first general zoölogical work, a thick octavo volume of 452 pages, entitled _Système des Animaux sans Vertèbres_, which appeared in 1801. Linné had divided all the animals below the vertebrates into two classes only, the Insecta and Vermes, the insects comprising the present classes of insects, Myriapoda, Arachnida, and Crustacea; the Vermes embracing all the other invertebrate animals, from the molluscs to the monads. Lamarck perceived the need of reform, of bringing order out of the chaotic mass of animal forms, and he says (p. 33) that he has been continually occupied since his attachment to the museum with this reform. He relies for his characters, the fundamental ones, on the organs of respiration, circulation, and on the form of the nervous system. The reasons he gives for his classification are sound and philosophical, and presented with the ease and aplomb of a master of taxonomy. He divided the invertebrates, which Cuvier had called animals with white blood, into the seven following classes. We place in a parallel column the classification of Cuvier in 1798. _Classification of Lamarck._ _Classification of Cuvier._ 1. Mollusca. I. _Mollusca._ 2. Crustacea. II. _Insectes et Vers._ 3. Arachnides (comprising 1. Insectes. the Myriapoda). 2. Vers. 4. Insectes. III. _Zoophytes._ 5. Vers. 1. Echinodermes. 2. Meduses, Animaux 6. Radiaires. infusorines, Rotifer, Vibrio, Volvox. 7. Polypes. 3. Zoophytes proprement dits. Of these, four were for the first time defined, and the others restricted. It will be noticed that he separates the Radiata (_Radiaires_) from the Polypes. His "Radiaires" included the Echinoderms (the _Vers echinoderms_ of Bruguière) and the Medusæ (his _Radiaires molasses_), the latter forming the Discophora and Siphonophora of present zoölogists. This is an anticipation of the division by Leuckart in 1839 of the Radiata of Cuvier into Coelenterata and Echinodermata. The "Polypes" of Lamarck included not only the forms now known as such, but also the Rotifera and Protozoa, though, as we shall see, he afterwards in his course of 1807 eliminated from this heterogeneous assemblage the Infusoria. Comparing this classification with that of Cuvier[121] published in 1798, we find that in the most important respects, _i.e._, the foundation of the classes of Crustacea, Arachnida, and Radiata, there is a great advance over Cuvier's system. In Cuvier's work the molluscs are separated from the worms, and they are divided into three groups, Cephalopodes, Gasteropodes, and Acephales--an arrangement which still holds, that of Lamarck into Mollusques céphalés and Mollusques acéphalés being much less natural. With the elimination of the Mollusca, Cuvier allowed the Vers or Vermes of Linné to remain undisturbed, except that the Zoöphytes, the equivalent of Lamarck's Polypes, are separately treated. He agrees with Cuvier in placing the molluscs at the head of the invertebrates, a course still pursued by some zoölogists at the present day. He states in the _Philosophie Zoologique_[122] that in his course of lectures of the year 1799 he established the class of Crustacea, and adds that "although this class is essentially distinct, it was not until six or seven years after that some naturalists consented to adopt it." The year following, or in his course of 1800, he separated from the insects the class of Arachnida, as "easy and necessary to be distinguished." But in 1809 he says that this class "is not yet admitted into any other work than my own."[123] As to the class of Annelides, he remarks: "Cuvier having discovered the existence of arterial and venous vessels in different animals which have been confounded under the name of worms (_Vers_) with other animals very differently organized, I immediately employed the consideration of this new fact in rendering my classification more perfect, and in my course of the year 10 (1802) I established the class of Annelides, a class which I have placed after the molluscs and before the crustaceans, as their known organization requires." He first established this class in his _Recherches sur les corps vivans_ (1802), but it was several years before it was adopted by naturalists. The next work in which Lamarck deals with the classification of the invertebrates is his _Discours d'ouverture du Cours des Animaux sans Vertèbres_, published in 1806. On page 70 he speaks of the animal chain or series, from the monad to man, ascending from the most simple to the most complex. The monad is one of his _Polypes amorphs_, and he says that it is the most simple animal form, the most like the original germ (_ébauche_) from which living bodies have descended. From the monad nature passes to the Volvox, Proteus (Amoeba), and Vibrio. From them are derived the _Polypes rotifères_ and other "Radiaires," and then the Vers, Arachnides, and Crustacea. On page 77 a tabular view is presented, as follows: 1. _Les Mollusques._ 2. _Les Cirrhipèdes._ 3. _Les Annelides._ 4. _Les Crustacés._ 5. _Les Arachnides._ 6. _Les Insectes._ 7. _Les Vers._ 8. _Les Radiaires._ 9. _Les Polypes._ It will be seen that at this date two additional classes are proposed and defined--_i.e._, the Annelides and the Cirrhipedes, though the class of Annelida was first privately characterized in his lectures for 1802. The elimination of the barnacles or Cirrhipedes from the molluscs was a decided step in advance, and was a proof of the acute observation and sound judgment of Lamarck. He says that this class is still very imperfectly known and its position doubtful, and adds: "The Cirrhipedes have up to the present time been placed among the molluscs, but although certain of them closely approach them in some respects, they have a special character which compels us to separate them. In short, in the genera best known the feet of these animals are distinctly articulated and even crustaceous (_crustacés_)." He does not refer to the nervous system, but this is done in his next work. It will be remembered that Cuvier overlooked this feature of the jointed limbs, and also the crustaceous-like nervous system of the barnacles, and allowed them to remain among the molluscs, notwithstanding the decisive step taken by Lamarck. It was not until many years after (1830) that Thompson proved by their life-history that barnacles are true crustacea. In the _Philosophie zoologique_ the ten classes of the invertebrates are arranged in the following order: _Les Mollusques._ _Les Cirrhipèdes._ _Les Annelides._ _Les Crustacés._ _Les Arachnides._ _Les Insectes._ _Les Vers._ _Les Radiaires._ _Les Polypes._ _Les Infusoires._ At the end of the second volume Lamarck gives a tabular view on a page by itself (p. 463), showing his conception of the origin of the different groups of animals. This is the first phylogeny or genealogical tree ever published. TABLEAU Servant à montrer l'origine des differens animaux. Vers. Infusoires. . Polypes. . Radiaires. . . . . . . . . Insectes. . Arachnides. Annelides. Crustacés. Cirrhipèdes. Mollusques. . . . Poissons. Reptiles. . . . . . Oiseaux. . . . . . Monotrèmes. M. Amphibies. . . . . . . . M. Cétacés. . . . M. Ongulés. M. Onguiculés. The next innovation made by Lamarck in the _Extrait du Cours de Zoologie_, in 1812, was not a happy one. In this work he distributed the fourteen classes of the animal kingdom into three groups, which he named _Animaux Apathiques_, _Sensibles_, and _Intelligens_. In this physiologico-psychological base for a classification he unwisely departed from his usual more solid foundation of anatomical structure, and the results were worthless. He, however, repeats it in his great work, _Histoire naturelle des Animaux sans Vertèbres_ (1815-1822). The sponges were by Cuvier, and also by Lamarck, accorded a position among the Polypes, near Alcyonium, which represents the latter's _Polypiers empâtés_; and it is interesting to notice that, for many years remaining among the Protozoa, meanwhile even by Agassiz regarded as vegetables, they were by Haeckel restored to a position among the Coelenterates, though for over twenty years they have by some American zoölogists been more correctly regarded as a separate phylum.[124] Lamarck also separated the seals and morses from the cetacea. Adopting his idea, Cuvier referred the seals to an order of carnivora. Another interesting matter, to which Professor Lacaze-Duthiers has called attention in his interesting letter on p. 77, is the position assigned _Lucernaria_ among his _Radiaires molasses_ near what are now Ctenophora and Medusæ, though one would have supposed he would, from its superficial resemblance to polyps, have placed it among the polyps. To Lamarck we are also indebted for the establishment in 1818 of the molluscan group of Heteropoda. Lamarck's acuteness is also shown in the fact that, whereas Cuvier placed them among the acephalous molluscs, he did not regard the ascidians as molluscs at all, but places them in a class by themselves under the name of _Tunicata_, following the Sipunculus worms. Yet he allowed them to remain near the Holothurians (then including Sipunculus) in his group of _Radiaires echinodermes_, between the latter and the Vers. He differs from Cuvier in regarding the tunic as the homologue of the shell of Lamellibranches, remarking that it differs in being muscular and contractile. Lamarck's fame as a zoölogist rests chiefly on this great work. It elicited the highest praise from his contemporaries. Besides containing the innovations made in the classification of the animal kingdom, which he had published in previous works, it was a summary of all which was then known of the invertebrate classes, thus forming a most convenient hand-book, since it mentioned all the known genera and all the known species except those of the insects, of which only the types are mentioned. It passed through two editions, and still is not without value to the working systematist. In his _Histoire des Progrès des Sciences naturelles_ Cuvier does it justice. Referring to the earlier volume, he states that "it has extended immensely the knowledge, especially by a new distribution, of the shelled molluscs ... M. de Lamarck has established with as much care as sagacity the genera of shells." Again he says, in noticing the three first volumes: "The great detail into which M. de Lamarck has entered, the new species he has described, renders his work very valuable to naturalists, and renders most desirable its prompt continuation, especially from the knowledge we have of means which this experienced professor possesses to carry to a high degree of perfection the enumeration which he will give us of the shells" (_Oeuvres complètes de Buffon_, 1828, t. 31, p. 354). "His excellences," says Cleland, speaking of Lamarck as a scientific observer, "were width of scope, fertility of ideas, and a preëminent faculty of precise description, arising not only from a singularly terse style, but from a clear insight into both the distinctive features and the resemblance of forms" (_Encyc. Britannica_, Art. LAMARCK). The work, moreover, is remarkable for being the first one to begin with the simplest and to end with the most highly developed forms. Lamarck's special line of study was the Mollusca. How his work is still regarded by malacologists is shown by the following letter from our leading student of molluscs, Dr. W. H. Dall: "SMITHSONIAN INSTITUTION, "UNITED STATES NATIONAL MUSEUM, WASHINGTON, D. C., "_November 4, 1899._ "Lamarck was one of the best naturalists of his time, when geniuses abounded. His work was the first well-marked step toward a natural system as opposed to the formalities of Linné. He owed something to Cuvier, yet he knew how to utilize the work in anatomy offered by Cuvier in making a natural classification. His failing eyesight, which obliged him latterly to trust to the eyes of others; his poverty and trials of various kinds, more than excuse the occasional slips which we find in some of the later volumes of the _Animaux sans Vertèbres_. These are rather of the character of typographical errors than faults of scheme or principle. "The work of Lamarck is really the foundation of rational natural malacological classification; practically all that came before his time was artificial in comparison. Work that came later was in the line of expansion and elaboration of Lamarck's, without any change of principle. Only with the application of embryology and microscopical work of the most modern type has there come any essential change of method, and this is rather a new method of getting at the facts than any fundamental change in the way of using them when found. I shall await your work on Lamarck's biography with great interest. "I remain, "Yours sincerely, "WILLIAM H. DALL." FOOTNOTES: [119] During the same period (1803-1829) Russia sent out expeditions to the North and Northeast, accompanied by the zoölogists Tilesius, Langsdorff, Chamisso, Eschscholtz, and Brandt, all of them of German birth and education. From 1823 to 1850 England fitted up and sent out exploring expeditions commanded by Beechey, Fitzroy, Belcher, Ross, Franklin, and Stanley, the naturalists of which were Bennett, Owen, Darwin, Adams, and Huxley. From Germany, less of a maritime country, at a later date, Humboldt, Spix, Prince Wied-Neuwied, Natterer, Perty, and others made memorable exploring expeditions and journeys. [120] These papers have been mercilessly criticised by Blainville in his "Cuvier et Geoffroy St. Hilaire." In the second article--_i.e._, on the anatomy of the limpet--Cuvier, in considering the organs, follows no definite plan; he gives a description "_tout-a-fait fantastique_" of the muscular fibres of the foot, and among other errors in this first essay on comparative anatomy he mistakes the tongue for the intromittent organ; the salivary glands, and what is probably part of the brain, being regarded as the testes, with other "_erreurs matérielles inconcevables, même à l'époque ou elle fut rédigée_." In his first article he mistakes a species of the myriapod genus Glomeris for the isopod genus Armadillo. In this he is corrected by the editor (possibly Lamarck himself), who remarks in a footnote that the forms to which M. Cuvier refers under the name of Armadillo are veritable species of Julus. We have verified these criticisms of Cuvier by reference to his papers in the "Journal." It is of interest to note, as Blainville does, that Cuvier at this period admits that there is a passage from the Isopoda to the armadilloes and Julus. Cuvier, then twenty-three years old, wrote: "_Nous sommes donc descendus par degrès, des Écrevisses aux Squilles, de celles-ci aux Aselles, puis aux Cloportes, aux Armadilles et aux Ïules_" (_Journal d'Hist. nat._, tom. ii., p. 29, 1792). These errors, as regards the limpet, were afterwards corrected by Cuvier (though he does not refer to his original papers) in his _Mémoires pour servir à l'Histoire et à l'Anatomie des Mollusques_ (1817). [121] _Tableau élémentaire de l'Histoire naturelle des Animaux._ Paris, An VI. (1798). 8vo, pp. 710. With 14 plates. [122] Tome i., p. 123. [123] In his _Histoire des Progrès des Sciences naturelles_ Cuvier takes to himself part of the credit of founding the class Crustacea, stating that Aristotle had already placed them in a class by themselves, and adding, "_MM. Cuvier et de Lamarck les en out distingués par des caractères de premier ordre tirés de leur circulation._" Undoubtedly Cuvier described the circulation, but it was Lamarck who actually realized the taxonomic importance of this feature and placed them in a distinct class. [124] See A. Hyatt's _Revision of North American Poriferæ_, Part II. (Boston, 1877, p. 11); also the present writer in his _Text-book of Zoölogy_ (1878). CHAPTER XIII THE EVOLUTIONARY VIEWS OF BUFFON AND OF GEOFFROY ST. HILAIRE Of the French precursors of Lamarck there were four--Duret (1609), De Maillet (1748), Robinet (1768), and Buffon. The opinions of the first three could hardly be taken seriously, as they were crude and fantastic, though involving the idea of descent. The suggestions and hypotheses of Buffon and of Erasmus Darwin were of quite a different order, and deserve careful consideration. [Illustration: MAISON DE BUFFON, IN WHICH LAMARCK LIVED, 1793-1829] George Louis Leclerc, Comte de Buffon, was born in 1707 at Montbard, Burgundy, in the same year as Linné. He died at Paris in 1788, at the age of eighty-one years. He inherited a large property from his father, who was a councillor of the parliament of Burgundy. He studied at Dijon, and travelled abroad. Buffon was rich, but, greatly to his credit, devoted all his life to the care of the Royal Garden and to writing his works, being a most prolific author. He was not an observer, not even a closet naturalist. "I have passed," he is reported to have said, "fifty years at my desk." Appointed in 1739, when he was thirty-two years old, Intendant of the Royal Garden, he divided his time between his retreat at Montbard and Paris, spending four months in Paris and the remainder of the year at Montbard, away from the distractions and dissipations of the capital. It is significant that he wrote his great _Histoire naturelle_ at Montbard and not at Paris, where were the collections of natural history. His biographer, Flourens, says: "What dominates in the character of Buffon is elevation, force, the love of greatness and glory; he loved magnificence in everything. His fine figure, his majestic air, seemed to have some relation with the greatness of his genius; and nature had refused him none of those qualities which could attract the attention of mankind. "Nothing is better known than the _naïveté_ of his self-esteem; he admired himself with perfect honesty, frankly, but good-naturedly." He was once asked how many great men he could really mention; he answered: "Five--Newton, Bacon, Leibnitz, Montesquieu, and myself." His admirable style gained him immediate reputation and glory throughout the world of letters. His famous epigram, "_Le style est l'homme même_" is familiar to every one. That his moral courage was scarcely of a high order is proved by his little affair with the theologians of the Sorbonne. Buffon was not of the stuff of which martyrs are made. His forte was that of a brilliant writer and most industrious compiler, a popularizer of science. He was at times a bold thinker; but his prudence, not to say timidity, in presenting in his ironical way his thoughts on the origin of things, is annoying, for we do not always understand what Buffon did really believe about the mutability or the fixity of species, as too plain speaking in the days he wrote often led to persecution and personal hazard.[125] His cosmological ideas were based on those of Burnet and Leibnitz. His geological notions were founded on the labors of Palissy, Steno, Woodward, and Whiston. He depended upon his friend Daubenton for anatomical facts, and on Gueneau de Montbéliard and the Abbé Bexon for his zoölogical data. As Flourens says, "Buffon was not exactly an observer: others observed and discovered for him. He discovered, himself, the observations of others; he sought for ideas, others sought facts for him." How fulsome his eulogists were is seen in the case of Flourens, who capped the climax in exclaiming, "Buffon is Leibnitz with the eloquence of Plato;" and he adds, "He did not write for savants: he wrote for all mankind." No one now reads Buffon, while the works of Réaumur, who preceded him, are nearly as valuable as ever, since they are packed with careful observations. The experiments of Redi, of Swammerdam, and of Vallisneri, and the observations of Réaumur, had no effect on Buffon, who maintained that, of the different forms of genesis, "spontaneous generation" is not only the most frequent and the most general, but the most ancient--namely, the primitive and the most universal.[126] Buffon by nature was unsystematic, and he possessed little of the spirit or aim of the true investigator. He left no technical papers or memoirs, or what we would call contributions to science. In his history of animals he began with the domestic breeds, and then described those of most general, popular interest, those most known. He knew, as Malesherbes claimed, little about the works even of Linné and other systematists, neither grasping their principles nor apparently caring to know their methods. His single positive addition to zoölogical science was generalizations on the geographical distribution of animals. He recognized that the animals of the tropical and southern portions of the old and new worlds were entirely unlike, while those of North America and northern Eurasia were in many cases the same. We will first bring together, as Flourens and also Butler have done, his scattered fragmentary views, or rather suggestions, on the fixity of species, and then present his thoughts on the mutability of species. "The species" is then "an abstract and general term."[127] "There only exist individuals and _suites_ of individuals, that is to say, species."[128] He also says that Nature "imprints on each species its unalterable characters;" that "each species has an equal right to creation;"[129] that species, even those nearest allied, "are separated by an interval over which nature cannot pass;"[130] and that "each species having been independently created, the first individuals have served as a model for their descendants."[131] Buffon, however, shows the true scientific spirit in speaking of final causes. "The pig," he says, "is not formed as an original, special, and perfect type; its type is compounded of that of many other animals. It has parts which are evidently useless, or which, at any rate, it cannot use." ... "But we, ever on the lookout to refer all parts to a certain end--when we can see no apparent use for them, suppose them to have hidden uses, and imagine connections which are without foundation, and serve only to obscure our perception of Nature as she really is: we fail to see that we thus rob philosophy of her true character, which is to inquire into the 'how' of these things--into the manner in which Nature acts--and that we substitute for this true object a vain idea, seeking to divine the 'why'--the ends which she has proposed in acting" (tome v., p. 104, 1755, _ex_ Butler). The volumes of the _Histoire naturelle_ on animals, beginning with tome iv., appeared in the years 1753 to 1767, or over a period of fourteen years. Butler, in his _Evolution, Old and New_, effectually disposes of Isidore Geoffroy St. Hilaire's statement that at the beginning of his work (tome iv., 1753) he affirms the fixity of species, while from 1761 to 1766 he declares for variability. But Butler asserts from his reading of the first edition that "from the very first chapter onward he leant strongly to mutability, even if he did not openly avow his belief in it.... The reader who turns to Buffon himself will find that the idea that Buffon took a less advanced position in his old age than he had taken in middle life is also without foundation"[132] (p. 104). But he had more to say on the other side, that of the mutability of species, and it is these tentative views that his commentators have assumed to have been his real sentiments or belief, and for this reason place Buffon among the evolutionists, though he had little or no idea of evolution in the enlarged and thoroughgoing sense of Lamarck. He states, however, that the presence of callosities on the legs of the camel and llama "are the unmistakable results of rubbing or friction; so also with the callosities of baboons and the pouched monkeys, and the double soles of man's feet."[133] In this point he anticipates Erasmus Darwin and Lamarck. As we shall see, however, his notions were much less firmly grounded than those of Erasmus Darwin, who was a close observer as well as a profound thinker. In his chapter on the _Dégénération des Animaux_, or, as it is translated, "modification of animals," Buffon insists that the three causes are climate, food, and domestication. The examples he gives are the sheep, which having originated, as he thought, from the mufflon, shows marked changes. The ox varies under the influence of food; reared where the pasturage is rich it is twice the size of those living in a dry country. The races of the torrid zones bear a hump on their shoulders; "the zebu, the buffalo, is, in short, only a variety, only a race of our domestic ox." He attributed the camel's hump to domesticity. He refers the changes of color in the northern hare to the simple change of seasons. He is most explicit in referring to the agency of climate, and also to time and to the uniformity of nature's processes in causing variation. Writing in 1756 he says: "If we consider each species in the different climates which it inhabits we shall find perceptible varieties as regards size and form; they all derive an impress to a greater or less extent from the climate in which they live. These changes are only made slowly and imperceptibly. Nature's great workman is time. He marches ever with an even pace and does nothing by leaps and bounds, but by degrees, gradations, and succession he does all things; and the changes which he works--at first imperceptible--become little by little perceptible, and show themselves eventually in results about which there can be no mistake. Nevertheless, animals in a free, wild state are perhaps less subject than any other living beings, man not excepted, to alterations, changes, and variations of all kinds. Being free to choose their own food and climate, they vary less than domestic animals vary."[134] The Buffonian factor of the direct influence of climate is not in general of so thoroughgoing a character as usually supposed by the commentators of Buffon. He generally applies it to the superficial changes, such as the increase or decrease in the amount of hair, or similar modifications not usually regarded as specific characters. The modifications due to the direct influence of climate may be effected, he says, within even a few generations. Under the head of geographical distribution (in tome ix., 1761), in which subject Buffon made his most original contribution to exact biology, he claims to have been the first "even to have suspected" that not a single tropical species is common to both eastern and western continents, but that the animals common to both continents are those adapted to a temperate or cold climate. He even anticipates the subject of migration in past geological times by supposing that those forms travelled from the Old World either over some land still unknown, or "more probably" over territory which has long since been submerged.[135] The mammoth "was certainly the greatest and strongest of all quadrupeds, but it has disappeared; and if so, how many smaller, feebler, and less remarkable species must have perished without leaving us any traces or even hints of their having existed? How many other species have changed their nature, that is to say, become perfected or degraded, through great changes in the distribution of land and ocean; through the cultivation or neglect of the country which they inhabit; through the long-continued effects of climatic changes, so that they are no longer the same animals that they once were. Yet of all living beings after man the quadrupeds are the ones whose nature is most fixed and form most constant; birds and fishes vary much more easily; insects still more again than these; and if we descend to plants, which certainly cannot be excluded from animated nature, we shall be surprised at the readiness with which species are seen to vary, and at the ease with which they change their forms and adopt new natures."[136] The following passages, debarring the error of deriving all the American from the Old World forms, and the mistake in supposing that the American forms grew smaller than their ancestors in the Old World, certainly smack of the principle of isolation and segregation, and this is Buffon's most important contribution to the theory of descent. "It is probable, then, that all the animals of the New World are derived from congeners in the Old, without any deviation from the ordinary course of nature. We may believe that, having become separated in the lapse of ages by vast oceans and countries which they could not traverse, they have gradually been affected by, and derived impressions from, a climate which has itself been modified so as to become a new one through the operations of those same causes which dissociated the individuals of the Old and the New World from one another; thus in the course of time they have grown smaller and changed their characters. This, however, should not prevent our classifying them as different species now, for the difference is no less real though it dates from the creation. _Nature, I maintain, is in a state of continual flux and movement. It is enough for man if he can grasp her as she is in his own time, and throw but a glance or two upon the past and future, so as to try and perceive what she may have been in former times and what one day she may attain to._"[137] Buffon thus suggests the principle of the struggle for existence to prevent overcrowding, resulting in the maintenance of the balance of nature: "It may be said that the movement of Nature turns upon two immovable pivots--one, the illimitable fecundity which she has given to all species; the other, the innumerable difficulties which reduce the results of that fecundity, and leave throughout time nearly the same quantity of individuals in every species; ... destruction and sterility follow closely upon excessive fecundity, and, independently of the contagion which follows inevitably upon overcrowding, each species has its own special sources of death and destruction, which are of themselves sufficient to compensate for excess in any past generation."[138] He also adds, "The species the least perfect, the most delicate, the most unwieldy, the least active, the most unarmed, etc., have already disappeared or will disappear."[139] On one occasion, in writing on the dog, he anticipates Erasmus Darwin and Lamarck in ascribing to the direct cause of modification the inner feelings of the animal modified, change of condition being the indirect cause.[140] He, however, did not suggest the idea of the transmission of acquired characters by heredity, and does not mention the word heredity. These are all the facts he stated; but though not an observer, Buffon was a broad thinker, and was led from these few data to generalize, as he could well do, from the breadth of his knowledge of geology gained from the works of his predecessors, from Leibnitz to Woodward and Whiston. "After the rapid glance," he says, "at these variations, which indicate to us the special changes undergone by each species, there arises a more important consideration, and the view of which is broader; it is that of the transformation (_changement_) of the species themselves; it is that more ancient modification which has gone on from time immemorial, which seems to have been made in each family or, if we prefer, in each of the genera in which were comprised more or less allied species."[141] In the beginning of his first volume he states "that we can descend by almost imperceptible degrees from the most perfect creature to the most formless matter--from the most highly organized animal to the most entirely inorganic substance. We will recognize this gradation as the great work of nature; and we will observe it not only as regards size and form, but also in respect of movements and in the successive generations of every species." "Hence," he continues, "arises the difficulty of arriving at any perfect system or method in dealing either with nature as a whole or even with any single one of her subdivisions. The gradations are so subtle that we are often obliged to make arbitrary divisions. Nature knows nothing about our classifications, and does not choose to lend herself to them without reasons. We therefore see a number of intermediate species and objects which it is very hard to classify, and which of necessity derange our system, whatever it may be."[142] This is all true, and was probably felt by Buffon's predecessors, but it does not imply that he thought these forms had descended from one another. "In thus comparing," he adds, "all the animals, and placing them each in its proper genus, we shall find that the two hundred species whose history we have given may be reduced to a quite small number of families or principal sources from which it is not impossible that all the others may have issued."[143] He then establishes, on the one hand, nine species which he regarded as isolated, and, on the other, fifteen principal genera, primitive sources or, as we would say, ancestral forms, from which he derived all the animals (mammals) known to him. Hence he believed that he could derive the dog, the jackal, the wolf, and the fox from a single one of these four species; yet he remarks, _per contra_, in 1753: "Although we cannot demonstrate that the production of a species by modification is a thing impossible to nature, the number of contrary probabilities is so enormous that, even philosophically, we can scarcely doubt it; for if any species has been produced by the modification of another, if the species of ass has been derived from that of the horse, this could have been done only successively and by gradual steps: there would have been between the horse and ass a great number of intermediate animals, the first of which would gradually differ from the nature of the horse, and the last would gradually approach that of the ass; and why do we not see to-day the representatives, the descendants of those intermediate species? Why are only the two extremes living?" (tome iv., p. 390). "If we once admit that the ass belongs to the horse family, and that it only differs from it because it has been modified (_dégénéré_), we may likewise say that the monkey is of the same family as man, that it is a modified man, that man and the monkey have had a common origin like the horse and ass, that each family has had but a single source, and even that all the animals have come from a single animal, which in the succession of ages has produced, while perfecting and modifying itself, all the races of other animals" (tome iv., p. 382). "If it were known that in the animals there had been, I do not say several species, but a single one which had been produced by modification from another species; if it were true that the ass is only a modified horse, there would be no limit to the power of nature, and we would not be wrong in supposing that from a single being she has known how to derive, with time, all the other organized beings" (_ibid._, p. 382). The next sentence, however, translated, reads as follows: "But no. It is certain from revelation that all animals have alike been favored with the grace of an act of direct creation, and that the first pair of every species issued fully formed from the hands of the Creator" (tome iv., p. 383). In which of these views did Buffon really believe? Yet they appear in the same volume, and not at different periods of his life. He actually does say in the same volume (iv., p. 358): "It is not impossible that all species may be derivations (_issues_)." In the same volume also (p. 215) he remarks: "There is in nature a general prototype in each species on which each individual is modelled, but which seems, in being realized, to change or become perfected by circumstances; so that, relatively to certain qualities, there is a singular (_bizarre_) variation in appearance in the succession of individuals, and at the same time a constancy in the entire species which appears to be admirable." And yet we find him saying at the same period of his life, in the previous volume, that species "are the only beings in nature, beings perpetual, as ancient, as permanent as she."[144] A few pages farther on in the same volume of the same work, apparently written at the same time, he is strongly and stoutly anti-evolutional, affirming: "The imprint of each species is a type whose principal features are graven in characters forever ineffaceable and permanent."[145] In this volume (iv., p. 55) he remarks that the senses, whether in man or in animals, may be greatly developed by exercise. The impression left on the mind, after reading Buffon, is that even if he threw out these suggestions and then retracted them, from fear of annoyance or even persecution from the bigots of his time, he did not himself always take them seriously, but rather jotted them down as passing thoughts. Certainly he did not present them in the formal, forcible, and scientific way that Erasmus Darwin did. The result is that the tentative views of Buffon, which have to be with much research extracted from the forty-four volumes of his works, would now be regarded as in a degree superficial and valueless. But they appeared thirty-four years before Lamarck's theory, and though not epoch-making, they are such as will render the name of Buffon memorable for all time. ÉTIENNE GEOFFROY ST. HILAIRE. Étienne Geoffroy St. Hilaire was born at Étampes, April 15, 1772. He died in Paris in 1844. He was destined for the church, but his tastes were for a scientific career. His acquaintance with the Abbé Haüy and Daubenton led him to study mineralogy. He was the means of liberating Haüy from a political prison; the Abbé, as the result of the events of August, 1792, being promptly set free at the request of the Academy of Sciences. The young Geoffroy was in his turn aided by the illustrious Haüy, who obtained for him the position of sub-guardian and demonstrator of mineralogy in the Cabinet of Natural History. At the early age of twenty-one years, as we have seen, he was elected professor of zoölogy in the museum, in charge of the department of mammals and birds. He was the means of securing for Cuvier, then of his own age, a position in the museum as professor-adjunct of comparative anatomy. For two years (1795 and 1796) the two youthful savants were inseparable, sharing the same apartments, the same table, the same amusements, the same studies, and their scientific papers were prepared in company and signed in common. [Illustration: É. GEOFFROY ST. HILAIRE] Geoffroy became a member of the great scientific commission sent to Egypt by Napoleon (1789-1802). By his boldness and presence of mind he, with Savigny and the botanist Delille, saved the treasures which at Alexandria had fallen into the hands of the English general in command. In 1808 he was charged by Napoleon with the duty of organizing public instruction in Portugal. Here again, by his address and firmness, he saved the collections and exchanges made there from the hands of the English. When thirty-six years old he was elected a member of the Institute. In 1818 he began to discuss philosophical anatomy, the doctrine of homologies; he also studied the embryology of the mammals, and was the founder of teratology. It was he who discovered the vestigial teeth of the baleen whale and those of embryo birds, and the bearing of this on the doctrine of descent must have been obvious to him. As early as 1795, before Lamarck had changed his views as to the stability of species, the young Geoffroy, then twenty-three years old, dared to claim that species may be only "_les diverses dégénérations d'un même type_." These views he did not abandon, nor, on the other hand, did he actively promulgate them. It was not until thirty years later, in his memoir on the anatomy of the gavials, that he began the series of his works bearing on the question of species. In 1831 was held the famous debates between himself and Cuvier in the Academy of Sciences. But the contest was not so much on the causes of the variation of species as on the doctrine of homologies and the unity of organization in the animal kingdom. In fact, Geoffroy did not adopt the views peculiar to his old friend Lamarck, but was rather a follower of Buffon. His views were preceded by two premises. The species is only "_fixé sous la raison du maintien de l'état conditionnel de son milieu ambiant_." It is modified, it changes, if the environment (_milieu ambiant_) varies, and according to the extent (selon la portée) of the variations of the latter.[146] As the result, among recent or living beings there are no essential differences as regards them--"_c'est le même cours d'événements_," or "_la même marche d'excitation_."[147] On the other hand, the _monde ambiant_ having undergone more or less considerable change from one geological epoch to another, the atmosphere having even varied in its chemical composition, and the conditions of respiration having been thus modified,[148] the beings then living would differ in structure from their ancestors of ancient times, and would differ from them according "to the degree of the modifying power."[149] Again, he says, "The animals living to-day have been derived by a series of uninterrupted generations from the extinct animals of the antediluvian world."[150] He gave as an example the crocodiles of the present day, which he believed to have descended from the fossil forms. While he admitted the possibility of one type passing into another, separated by characters of more than generic value, he always, according to his son Isidore, rejected the view which made all the living species descend "_d'une espèce antediluvienne primitive_."[151] It will be seen that Geoffroy St. Hilaire's views were chiefly based on palæontological evidence. He was throughout broad and philosophical, and his eloquent demonstration in his _Philosophie anatomique_ of the doctrine of homologies served to prepare the way for modern morphology, and affords one of the foundation stones on which rests the theory of descent. Though temporarily vanquished in the debate with Cuvier, who was a forceful debater and represented the views then prevalent, a later generation acknowledges that he was in the right, and remembers him as one of the founders of evolution. FOOTNOTES: [125] Mr. Morley, in his _Rousseau_, gives a startling picture of the hostility of the parliament at the period (1762) when Buffon's works appeared. Not only was Rousseau hunted out of France, and his books burnt by the public executioner, but there was "hardly a single man of letters of that time who escaped arbitrary imprisonment" (p. 270); among others thus imprisoned was Diderot. At this time (1750-1765) Malesherbes (born 1721, guillotined 1794), one of the "best instructed and most enlightened men of the century," was Directeur de la Libraire. "The process was this: a book was submitted to him; he named a censor for it; on the censor's report the director gave or refused permission to print or required alterations. Even after these formalities were complied with, the book was liable to a decree of the royal council, a decree of the parliament, or else a lettre-de-cachet might send the author to the Bastille" (Morley's _Rousseau_, p. 266). [126] _Histoire naturelle, générale et particulière._ 1st edition. Imprimerie royale. Paris: 1749-1804, 44 vols. 4to. Tome iv., p. 357. This is the best of all the editions of Buffon, says Flourens, from whose _Histoire des Travaux et des Idées de Buffon_, 1st edition (Paris, 1844), we take some of the quotations and references, which, however, we have verified. We have also quoted some passages from Buffon translated by Butler in his "Evolution, Old and New" (London, 1879). [127] _L. c._, tome iv., p. 384 (1753). This is the first volume on the animals below man. [128] Tome xi., p. 369 (1764). [129] Tome xii., p. 3 (1764). [130] Tome v., p. 59 (1755). [131] Tome xiii., p. vii. (1765). [132] Osborn adopts, without warrant we think, Isidore Geoffroy St. Hilaire's notion, stating that he "shows clearly that his opinions marked three periods." The writings of Isidore, the son of Étienne Geoffroy, have not the vigor, exactness, or depth of those of his father. [133] Tome xiv., p. 326 (1766). [134] Tome vi., pp. 59-60 (1756). [135] Butler, _l. c._, pp. 145-146. [136] Tome ix., p. 127, 1761 (_ex_ Butler). [137] Tome ix., p. 127, 1761 (_ex_ Butler). [138] Tome vi., p. 252, 1756 (quoted from Butler, _l. c._, pp. 123-126). [139] Quoted from Osborn, who takes it from De Lanessan. [140] Butler, _l. c._, p. 122 (from Buffon, tome v., 1755). [141] Tome xiv., p. 335 (1766). [142] Tome i., p. 13. [143] Tome xiv., p. 358. [144] Tome xiii., p. i. [145] Tome xiii., p. ix. [146] _Études progressives d'un Naturaliste_, etc., 1835, p. 107. [147] _Ibid._ [148] _Sur l'Influence du Monde ambiant pour modifier les Formes animaux (Mémoires Acad. Sciences_, xii., 1833, pp. 63, 75). [149] _Recherches sur l'Organisation des Gavials (Mémoires du Muséum d'Histoire naturelle_), xii., p. 97 (1825). [150] _Sur l'Influence du Monde ambiant_, p. 74. [151] _Dictionnaire de la Conversation_, xxxi., p. 487, 1836 (quoted by I. Geoffroy St. Hilaire); _Histoire nat. gén. des Règnes organiques_, ii., 2^e partie; also _Résumé_, p. 30 (1859). CHAPTER XIV THE VIEWS OF ERASMUS DARWIN Erasmus Darwin, the grandfather of Charles Darwin, was born in 1731, or twenty-four years after Buffon. He was an English country physician with a large practice, and not only interested in philosophy, mechanics, and natural science, but given to didactic rhyming, as evinced by _The Botanical Garden_ and _The Loves of the Plants_, the latter of which was translated into French in 1800, and into Italian in 1805. His "shrewd and homely mind," his powers of keen observation and strong common sense were revealed in his celebrated work _Zoonomia_, which was published in two volumes in 1794, and translated into German in 1795-99. He was not a zoölogist, published no separate scientific articles, and his striking and original views on evolution, which were so far in advance of his time, appear mostly in the section on "Generation," comprising 173 pages of his _Zoonomia_,[152] which was mainly a medical work. The book was widely read, excited much discussion, and his views decided opposition. Samuel Butler in his _Evolution, Old and New_ (1879) remarks: "Paley's _Natural Theology_ is written throughout at the _Zoonomia_, though he is careful, _moro suo_, never to mention this work by name. Paley's success was probably one of the chief causes of the neglect into which the Buffonian and Darwinian systems fell in this country." Dr. Darwin died in the same year (1802) as that in which the _Natural Theology_ was published. Krause also writes of the reception given by his contemporaries to his "physio-philosophical ideas." "They spoke of his wild and eccentric fancies, and the expression 'Darwinising' (as employed, for example, by the poet Coleridge when writing on Stillingfleet) was accepted in England nearly as the antithesis of sober biological investigation."[153] The grandson of Erasmus Darwin had little appreciation of the views of him of whom, through atavic heredity, he was the intellectual and scientific child. "It is curious," he says in the 'Historical Sketch' of the _Origin of Species_--"it is curious how largely my grandfather, Dr. Erasmus Darwin, anticipated the views and erroneous grounds of opinion of Lamarck in his _Zoonomia_ (vol. i., pp. 500-510), published in 1794." It seems a little strange that Charles Darwin did not devote a few lines to stating just what his ancestor's views were, for certain of them, as we shall see, are anticipations of his own. The views of Erasmus Darwin may thus be summarily stated: 1. All animals have originated "from a single living filament" (p. 230), or, stated in other words, referring to the warm-blooded animals alone, "one is led to conclude that they have alike been produced from a similar living filament" (p. 236); and again he expresses the conjecture that one and the same kind of living filament is and has been the cause of all organic life (p. 244). It does not follow that he was a "spermist," since he strongly argued against the incasement or "evolution" theory of Bonnet. 2. Changes produced by differences of climate and even seasons. Thus "the sheep of warm climates are covered with hair instead of wool, and the hares and partridges of the latitudes which are long buried in snow become white during the winter months" (p. 234). Only a passing reference is made to this factor, and the effects of domestication are but cursorily referred to. In this respect Darwin's views differed much from Buffon's, with whom they were the primary causes in the modification of animals. The other factors or agencies are not referred to by Buffon, showing that Darwin was not indebted to Buffon, but thought out the matter in his own independent way. 3. "Fifthly, from their first rudiment or primordium to the termination of their lives, all animals undergo perpetual transformations, which are in part produced by their own exertions in consequence of their desires and aversions, of their pleasures and their pains, or of irritations or of associations; and many of these acquired forms or propensities are transmitted to their posterity" (p. 237). The three great objects of desire are, he says, "lust, hunger, and security" (p. 237). 4. Contests of the males for the possession of the females, or law of battle. Under the head of desire he dwells on the desire of the male for the exclusive possession of the female; and "these have acquired weapons to combat each other for this purpose," as the very thick, shield-like horny skin on the shoulders of the boar, and his tusks, the horns of the stag, the spurs of cocks and quails. "The final cause," he says, "of this contest among the males seems to be that the strongest and most active animal should propagate the species, which should thence become improved" (p. 238). This savors so strongly of sexual selection that we wonder very much that Charles Darwin repudiated it as "erroneous." It is not mentioned by Lamarck, nor is Dr. Darwin's statement of the exertions and desires of animals at all similar to Lamarck's, who could not have borrowed his ideas on appetency from Darwin or any other predecessor. 5. The transmission of characters acquired during the lifetime of the parent. This is suggested in the following crude way: "Thirdly, when we enumerate the great changes produced in the species of animals before their maturity, as, for example, when the offspring reproduces the effects produced upon the parent by accident or cultivation; or the changes produced by the mixture of species, as in mules; or the changes produced probably by the exuberance of nourishment supplied to the fetus, as in monstrous births with additional limbs, many of these enormities of shape are propagated and continued as a variety, at least, if not as a new species of animal. I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw, and with wings to their feet, and of others without rumps. Mr. Buffon mentions a breed of dogs without tails, which are common at Rome and Naples, which he supposes to have been produced by a custom, long established, of cutting their tails close off. There are many kinds of pigeons admired for their peculiarities which are more or less thus produced and propagated."[154] 6. The means of procuring food has, he says, "diversified the forms of all species of animals. Thus the nose of the swine has become hard for the purpose of turning up the soil in search of insects and of roots. The trunk of the elephant is an elongation of the nose for the purpose of pulling down the branches of trees for his food, and for taking up water without bending his knees. Beasts of prey have acquired strong jaws or talons. Cattle have acquired a rough tongue and a rough palate to pull off the blades of grass, as cows and sheep. Some birds have acquired harder beaks to crack nuts, as the parrot. Others have acquired beaks to break the harder seeds, as sparrows. Others for the softer kinds of flowers, or the buds of trees, as the finches. Other birds have acquired long beaks to penetrate the moister soils in search of insects or roots, as woodcocks, and others broad ones to filtrate the water of lakes and to retain aquatic insects. All which seem to have been gradually produced during many generations by the perpetual endeavors of the creature to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purpose required" (p. 238). 7. The third great want among animals is that of security, which seems to have diversified the forms of their bodies and the color of them; these consist in the means of escaping other animals more powerful than themselves.[155] Hence some animals have acquired wings instead of legs, as the smaller birds, for purposes of escape. Others, great length of fin or of membrane, as the flying-fish and the bat. Others have acquired hard or armed shells, as the tortoise and the Echinus marinus (p. 239). "The colors of insects," he says, "and many smaller animals contribute to conceal them from the dangers which prey upon them. Caterpillars which feed on leaves are generally green; earthworms the color of the earth which they inhabit; butterflies, which frequent flowers, are colored like them; small birds which frequent hedges have greenish backs like the leaves, and light-colored bellies like the sky, and are hence less visible to the hawk, who passes under them or over them. Those birds which are much amongst flowers, as the goldfinch (_Fringilla carduelis_), are furnished with vivid colors. The lark, partridge, hare, are the color of dry vegetables or earth on which they rest. And frogs vary their color with the mud of the streams which they frequent; and those which live on trees are green. Fish, which are generally suspended in water, and swallows, which are generally suspended in air, have their backs the color of the distant ground, and their bellies of the sky. In the colder climates many of these become white during the existence of the snows. Hence there is apparent design in the colors of animals, whilst those of vegetables seem consequent to the other properties of the materials which possess them" (_The Loves of the Plants_, p. 38, note). In his _Zoonomia_ (§ xxxix., vi.) Darwin also speaks of the efficient cause of the various colors of the eggs of birds and of the hair and feathers of animals which are adapted to the purpose of concealment. "Thus the snake, and wild cat, and leopard are so colored as to resemble dark leaves and their light interstices" (p. 248). The eggs of hedge-birds are greenish, with dark spots; those of crows and magpies, which are seen from beneath through wicker nests, are white, with dark spots; and those of larks and partridges are russet or brown, like their nests or situations. He adds: "The final cause of their colors is easily understood, as they serve some purpose of the animal, but the efficient cause would seem almost beyond conjecture." Of all this subject of protective mimicry thus sketched out by the older Darwin, we find no hint or trace in any of Lamarck's writings. 8. Great length of time. He speaks of the "great length of time since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind" (p. 240). In this connection it may be observed that Dr. Darwin emphatically opposes the preformation views of Haller and Bonnet in these words: "Many ingenious philosophers have found so great difficulty in conceiving the manner of the reproduction of animals that they have supposed all the numerous progeny to have existed in miniature in the animal originally created, and that these infinitely minute forms are only evolved or distended as the embryon increases in the womb. This idea, besides being unsupported by any analogy we are acquainted with, ascribes a greater tenuity to organized matter than we can readily admit" (p. 317); and in another place he claims that "we cannot but be convinced that the fetus or embryon is formed by apposition of new parts, and not by the distention of a primordial nest of germs included one within another like the cups of a conjurer" (p. 235). 9. To explain instinct he suggests that the young simply imitate the acts or example of their parents. He says that wild birds choose spring as their building time "from the acquired knowledge that the mild temperature of the air is more convenient for hatching their eggs;" and further on, referring to the fact that seed-eating animals generally produce their young in spring, he suggests that it is "part of the traditional knowledge which they learn from the example of their parents."[156] 10. Hybridity. He refers in a cursory way to the changes produced by the mixture of species, as in mules. Of these ten factors or principles, and other views of Dr. Darwin, some are similar to those of Lamarck, while others are directly opposed. There are therefore no good grounds for supposing that Lamarck was indebted to Darwin for his views. Thus Erasmus Darwin supposes that the formation of organs precedes their use. As he says, "The lungs must be previously formed before their exertions to obtain fresh air can exist; the throat or oesophagus must be formed previous to the sensation or appetites of hunger and thirst" (_Zoonomia_, p. 222). Again (_Zoonomia_, i., p. 498), "From hence I conclude that with the acquisition of new parts, new sensations and new desires, as well as new powers, are produced" (p. 226). Lamarck does not carry his doctrine of use-inheritance so far as Erasmus Darwin, who claimed, what some still maintain at the present day, that the offspring reproduces "the effects produced upon the parent by accident or cultivation." The idea that all animals have descended from a similar living filament is expressed in a more modern and scientific way by Lamarck, who derived them from monads. The Erasmus Darwin way of stating that the transformations of animals are in part produced by their own exertions in consequence of their desires and aversions, etc., is stated in a quite different way by Lamarck. Finally the principle of law of battle, or the combat between the males for the possession of the females, with the result "that the strongest and most active animal should propagate the species," is not hinted at by Lamarck. This view, on the contrary, is one of the fundamental principles of the doctrine of natural selection, and was made use of by Charles Darwin and others. So also Erasmus anticipated Charles Darwin in the third great want of "security," in seeking which the forms and colors of animals have been modified. This is an anticipation of the principle of protective mimicry, so much discussed in these days by Darwin, Wallace, and others, and which was not even mentioned by Lamarck. From the internal evidence of Lamarck's writings we therefore infer that he was in no way indebted to Erasmus Darwin for any hints or ideas.[157] FOOTNOTES: [152] Vol. ii., 3d edition. Our references are to this edition. [153] Krause, _The Scientific Works of Erasmus Darwin_, footnote on p. 134: "See 'Athenæum,' March, 1875, p. 423." [154] _Zoonomia_, i., p. 505 (3d edition, p. 335). [155] The subject of protective mimicry is more explicitly stated by Dr. Darwin in his earlier book, _The Loves of the Plants_, and, as Krause states, though Rösel von Rosenhof in his _Insekten-Belustigungen_ (Nurnberg, 1746) describes the resemblance which geometric caterpillars, and also certain moths when in repose, present to dry twigs, and thus conceal themselves, "this group of phenomena seems to have been first regarded from a more general point of view by Dr. Darwin." [156] _Zoonomia_, vol. i., p. 170. [157] Mr. Samuel Butler, in his _Evolution, Old and New_, taking it for granted that Lamarck was "a partisan of immutability till 1801," intimates that "the secret of this sudden conversion must be found in a French translation by M. Deleuze of Dr. Darwin's poem, _The Loves of the Plants_, which appeared in 1800. Lamarck--the most eminent botanist of his time--was sure to have heard of and seen this, and would probably know the translator, who would be able to give him a fair idea of the _Zoonomia_" (p. 258). But this notion seems disproved by the fact that Lamarck delivered his famous lecture, published in 1801, during the last of April or in the first half of May, 1800. The views then presented must have been formed in his mind at least for some time--perhaps a year or more--previous, and were the result of no sudden inspiration, least of all from any information given him by Deleuze, whom he probably never met. If Lamarck had actually seen and read the _Zoonomia_ he would have been manly enough to have given him credit for any novel ideas. Besides that, as we have already seen, the internal evidence shows that Lamarck's views were in some important points entirely different from those of Erasmus Darwin, and were conceptions original with the French zoölogist. Krause in his excellent essay on the scientific works of Erasmus Darwin (1879) refers to Lamarck as "evidently a disciple of Darwin," stating that Lamarck worked out "in all directions" Erasmus Darwin's principles of "will and active efforts" (p. 212). CHAPTER XV WHEN DID LAMARCK CHANGE HIS VIEWS REGARDING THE MUTABILITY OF SPECIES? Lamarck's mind was essentially philosophical. He was given to inquiring into the causes and origin of things. When thirty-two years old he wrote his "Researches on the Causes of the Principal Physical Facts," though this work did not appear from the press until 1794, when he was fifty years of age. In this treatise he inquires into the origin of compounds and of minerals; also he conceived that all the rocks as well as all chemical compounds and minerals originated from organic life. These inquiries were reiterated in his "Memoirs on Physics and Natural History," which appeared in 1797, when he was fifty-three years old. The atmosphere of philosophic France, as well as of England and Germany in the eighteenth century, was charged with inquiries into the origin of things material, though more especially of things immaterial. It was a period of energetic thinking. Whether Lamarck had read the works of these philosophers or not we have no means of knowing. Buffon, we know, was influenced by Leibnitz. Did Buffon's guarded suggestions have no influence on the young Lamarck? He enjoyed his friendship and patronage in early life, frequenting his house, and was for a time the travelling companion of Buffon's son. It should seem most natural that he would have been personally influenced by his great predecessor, but we see no indubitable trace of such influence in his writings. Lamarckism is not Buffonism. It comprises in the main quite a different, more varied and comprehensive set of factors.[158] Was Lamarck influenced by the biological writings of Haller, Bonnet, or by the philosophic views of Condillac, whose _Essai sur l'Origine des Connaissances humaines_ appeared in 1786; or of Condorcet, whom he must personally have known, and whose _Esquisse d'un Tableau historique des Progrès de l'Esprit humain_ was published in 1794?[159] In one case only in Lamarck's works do we find reference to these thinkers. Was Lamarck, as the result of his botanical studies from 1768 to 1793, and being puzzled, as systematic botanists are, by the variations of the more plastic species of plants, led to deny the fixity of species? We have been unable to find any indications of a change of views in his botanical writings, though his papers are prefaced by philosophical reflections. It would indeed be interesting to know what led Lamarck to change his views. Without any explanation as to the reason from his own pen, we are led to suppose that his studies on the invertebrates, his perception of the gradations in the animal scale from monad to man, together with his inherent propensity to inquire into the origin of things, also his studies on fossils, as well as the broadening nature of his zoölogical investigations and his meditations during the closing years of the eighteenth century, must gradually have led to a change of views. It was said by Isidore Geoffroy St. Hilaire that Lamarck was "long a partisan of the immutability of species,"[160] but the use of the word "partisan" appears to be quite incorrect, as he only in one instance expresses such views. The only place where we have seen any statement of Lamarck's earlier opinions is in his _Recherches sur les Causes des principaux Faits physiques_, which was written, as the "advertisement" states, "about eighteen years" before its publication in 1794. The treatise was actually presented April 22, 1780, to the Académie des Sciences.[161] It will be seen by the following passages, which we translate, that, as Huxley states, this view presents a striking contrast to those to be found in the _Philosophie zoologique_: "685. Although my sole object in this article [article premier, p. 188] has only been to treat of the physical cause of the maintenance of life of organic beings, still I have ventured to urge at the outset that the existence of these astonishing beings by no means depends on nature; that all which is meant by the word nature cannot give life--namely, that all the faculties of matter, added to all possible circumstances, and even to the activity pervading the universe, cannot produce a being endowed with the power of organic movement, capable of reproducing its like, and subject to death. "686. All the individuals of this nature which exist are derived from similar individuals, which, all taken together, constitute the entire species. However, I believe that it is as impossible for man to know the physical origin of the first individual of each species as to assign also physically the cause of the existence of matter or of the whole universe. This is at least what the result of my knowledge and reflection leads me to think. If there exist any varieties produced by the action of circumstances, these varieties do not change the nature of the species (_ces variétés ne dénaturent point les espèces_); but doubtless we are often deceived in indicating as a species what is only a variety; and I perceive that this error may be of consequence in reasoning on this subject" (tome ii., pp. 213-214). It must apparently remain a matter of uncertainty whether this opinion, so decisively stated, was that of Lamarck at thirty-two years of age, and which he allowed to remain, as then stated, for eighteen years, or whether he inserted it when reading the proofs in 1794. It would seem as if it were the expression of his views when a botanist and a young man. In his _Mémoires de Physique et d'Histoire naturelle_, which was published in 1797, there is nothing said bearing on the stability of species, and though his work is largely a repetition of the _Recherches_, the author omits the passages quoted above. Was this period of six years, between 1794 and 1800, given to a reconsideration of the subject resulting in favor of the doctrine of descent? Huxley quotes these passages, and then in a footnote (p. 211), after stating that Lamarck's _Recherches_ was not published before 1794, and stating that at that time it presumably expressed Lamarck's mature views, adds: "It would be interesting to know what brought about the change of opinion manifested in the _Recherches sur l'Organisation des Corps vivans_, published only seven years later." In the appendix to this book (1802) he thus refers to his change of views: "I have for a long time thought that _species_ were constant in nature, and that they were constituted by the individuals which belong to each of them. I am now convinced that I was in error in this respect, and that in reality only individuals exist in nature" (p. 141). Some clew in answer to the question as to when Lamarck changed his views is afforded by an almost casual statement by Lamarck in the addition entitled _Sur les Fossiles_ to his _Système des Animaux sans Vertèbres_ (1801), where, after speaking of fossils as extremely valuable monuments for the study of the revolutions the earth has passed through at different regions on its surface, and of the changes living beings have there themselves successively undergone, he adds in parenthesis: "_Dans mes leçons j'ai toujours insiste sur ces considérations._" Are we to infer from this that these evolutionary views were expressed in his first course, or in one of the earlier courses of zoölogical lectures--_i.e._, soon after his appointment in 1793--and if not then, at least one or two, or perhaps several, years before the year 1800? For even if the change in his views were comparatively sudden, he must have meditated upon the subject for months and even, perhaps, years, before finally committing himself to these views in print. So strong and bold a thinker as Lamarck had already shown himself in these fields of thought, and one so inflexible and unyielding in holding to an opinion once formed as he, must have arrived at such views only after long reflection. There is also every reason to suppose that Lamarck's theory of descent was conceived by himself alone, from the evidence which lay before him in the plants and animals he had so well studied for the preceding thirty years, and that his inspiration came directly from nature and not from Buffon, and least of all from the writings of Erasmus Darwin. FOOTNOTES: [158] See the comparative summary of the views of the founders of evolution at the end of Chapter XVII. [159] While Rousseau was living at Montmorency "his thought wandered confusedly round the notion of a treatise to be called 'Sensitive Morality or the Materialism of the Age,' the object of which was to examine the influence of external agencies, such as light, darkness, sound, seasons, food, noise, silence, motion, rest, on our corporeal machine, and thus, indirectly, upon the soul also."--_Rousseau_, by John Morley (p. 164). [160] Butler's _Evolution, Old and New_ (p. 244), and Isidore Geoffroy St. Hilaire's _Histoire naturelle générale_, tome ii., p. 404 (1859). [161] After looking in vain through both volumes of the _Recherches_ for some expression of Lamarck's earlier views, I found a mention of it in Osborn's _From the Greeks to Darwin_, p. 152, and reference to Huxley's _Evolution in Biology_, 1878 ("Darwiniana," p. 210), where the paragraphs translated above are quoted in the original. CHAPTER XVI THE STEPS IN THE DEVELOPMENT OF LAMARCK'S VIEWS ON EVOLUTION BEFORE THE PUBLICATION OF HIS _PHILOSOPHIE ZOOLOGIQUE_ I. _From the Système des Animaux sans Vertèbres_ (1801). The first occasion on which, so far as his published writings show, Lamarck expressed his evolutional views was in the opening lecture[162] of his course on the invertebrate animals delivered in the spring of 1800, and published in 1801 as a preface to his _Système des Animaux sans Vertèbres_, this being the first sketch or prodromus of his later great work on the invertebrate animals. In the preface of this book, referring to the opening lecture, he says: "I have glanced at some important and philosophic views that the nature and limits of this work do not permit me to develop, but which I propose to take up elsewhere with the details necessary to show on what facts they are based, and with certain explanations which would prevent any one from misunderstanding them." It may be inferred from this that he had for some time previous meditated on this theme. It will now be interesting to see what factors of evolution Lamarck employed in this first sketch of his theory. After stating the distinctions existing between the vertebrate and invertebrate animals, and referring to the great diversity of animal forms, he goes on to say that Nature began with the most simply organized, and having formed them, "then with the aid of much time and of favorable circumstances she formed all the others." "It appears, as I have already said, that _time_ and _favorable conditions_ are the two principal means which nature has employed in giving existence to all her productions. We know that for her time has no limit, and that consequently she has it always at her disposal. "As to the circumstances of which she has had need and of which she makes use every day in order to cause her productions to vary, we can say that they are in a manner inexhaustible. "The essential ones arise from the influence and from all the environing media (_milieux_), from the diversity of local causes (_diversité des lieux_), of habits, of movements, of action, finally of means of living, of preserving their lives, of defending themselves, of multiplying themselves, etc. Moreover, as the result of these different influences the faculties, developed and strengthened by use (_usage_), became diversified by the new habits maintained for long ages, and by slow degrees the structure, the consistence, in a word the nature, the condition of the parts and of the organs consequently participating in all these influences, became preserved and were propagated by generation.[163] "The bird which necessity (_besoin_) drives to the water to find there the prey needed for its subsistence separates the toes of its feet when it wishes to strike the water[164] and move on its surface. The skin, which unites these toes at their base, contracts in this way the habit of extending itself. Thus in time the broad membranes which connect the toes of ducks, geese, etc., are formed in the way indicated. "But one accustomed to live perched on trees has necessarily the end of the toes lengthened and shaped in another way. Its claws are elongated, sharpened, and are curved and bent so as to seize the branches on which it so often rests. "Likewise we perceive that the shore bird, which does not care to swim, but which, however, is obliged (a _besoin_) to approach the water to obtain its prey, will be continually in danger of sinking in the mud, but wishing to act so that its body shall not fall into the liquid, it will contract the habit of extending and lengthening its feet. Hence it will result in the generations of these birds which continue to live in this manner, that the individuals will find themselves raised as if on stilts, on long naked feet; namely, denuded of feathers up to and often above the thighs. "I could here pass in review all the classes, all the orders, all the genera and species of animals which exist, and make it apparent that the conformation of individuals and of their parts, their organs, their faculties, etc., is entirely the result of circumstances to which the race of each species has been subjected by nature. "I could prove that it is not the form either of the body or of its parts which gives rise to habits, to the mode of life of animals, but, on the contrary, it is the habits, the mode of life, and all the influential circumstances which have, with time, made up the form of the body and of the parts of animals. With the new forms new faculties have been acquired, and gradually nature has reached the state in which we actually see her" (pp. 12-15). He then points out the gradation which exists from the most simple animal up to the most composite, since from the monad, which, so to speak, is only an animated point, up to the mammals, and from them up to man, there is evidently a shaded gradation in the structure of all the animals. So also among the plants there is a graduated series from the simplest, such as _Mucor viridescens_, up to the most complicated plant. But he hastens to say that by this regular gradation in the complication of the organization he does not mean to infer the existence of a linear series, with regular intervals between the species and genera: "Such a series does not exist; but I speak of a series almost regularly graduated in the principal groups (_masses_) such as the great families; series most assuredly existing, both among animals and among plants, but which, as regards genera and especially species, form in many places lateral ramifications, whose extremities offer truly isolated points." This is the first time in the history of biological science that we have stated in so scientific, broad, and modern form the essential principles of evolution. Lamarck insists that time without limit and favorable conditions are the two principal means or factors in the production of plants and animals. Under the head of favorable conditions he enumerates variations in climate, temperature, the action of the environment, the diversity of local causes, change of habits, movement, action, variation in means of living, of preservation of life, of means of defence, and varying modes of reproduction. As the result of the action of these different factors, the faculties of animals, developed and strengthened by use, become diversified by the new habits, so that by slow degrees the new structures and organs thus arising become preserved and transmitted by heredity. In this address it should be noticed that nothing is said of willing and of internal feeling, which have been so much misunderstood and ridiculed, or of the direct or indirect action of the environment. He does speak of the bird as wishing to strike the water, but this, liberally interpreted, is as much a physiological impulse as a mental desire. No reference also is made to geographical isolation, a factor which he afterwards briefly mentioned. Although Lamarck does not mention the principle of selection, he refers in the following way to competition, or at least to the checks on the too rapid multiplication of the lower invertebrates: "So were it not for the immense consumption as food which is made in nature of animals which compose the lower orders of the animal kingdom, these animals would soon overpower and perhaps destroy, by their enormous numbers, the more highly organized and perfect animals which compose the first classes and the first orders of this kingdom, so great is the difference in the means and facility of multiplying between the two. "But nature has anticipated the dangerous effects of this vast power of reproduction and multiplication. She has prevented it on the one hand by considerably limiting the duration of life of these beings so simply organized which compose the lower classes, and especially the lowest orders of the animal kingdom. On the other hand, both by making these animals the prey of each other, thus incessantly reducing their numbers, and also by determining through the diversity of climates the localities where they could exist, and by the variety of seasons--_i.e._, by the influences of different atmospheric conditions--the time during which they could maintain their existence. "By means of these wise precautions of nature everything is well balanced and in order. Individuals multiply, propagate, and die in different ways. No species predominates up to the point of effecting the extinction of another, except, perhaps, in the highest classes, where the multiplication of the individuals is slow and difficult; and as the result of this state of things we conceive that in general species are preserved" (p. 22). Here we have in anticipation the doctrine of Malthus, which, as will be remembered, so much impressed Charles Darwin, and led him in part to work out his principle of natural selection. The author then taking up other subjects, first asserts that among the changes that animals and plants unceasingly bring about by their production and _débris_, it is not the largest and most perfect animals which have caused the most considerable changes, but rather the coral polyps, etc.[165] He then, after dilating on the value of the study of the invertebrate animals, proceeds to define them, and closes his lecture by describing the seven classes into which he divides this group. II. _Recherches sur l'Organisation des Corps vivans, 1802 (Opening Discourse)._ The following is an abstract with translations of the most important passages relating to evolution: That the portion of the animal kingdom treated in these lectures comprises more species than all the other groups taken together is, however, the least of those considerations which should interest my hearers. "It is the group containing the most curious forms, the richest in marvels of every kind, the most astonishing, especially from the singular facts of organization that they present, though it is that hitherto the least considered under these grand points of view. "How much better than learning the names and characters of all the species is it to learn of the origin, relation, and mode of existence of all the natural productions with which we are surrounded. "_First Part: Progress in structure of living beings in proportion as circumstances favor them._ "When we give continued attention to the examination of the organization of different living beings, to that of different systems which this organization presents in each organic kingdom, finally to certain changes which are seen to be undergone in certain circumstances, we are convinced: "1. That the nature of organic movement is not only to develop the organization but also to multiply the organs and to fulfil the functions, and that at the outset this organic movement continually tends to restrict to functions special to certain parts the functions which were at first general--_i.e._, common to all parts of the body; "2. That the result of _nutrition_ is not only to supply to the developing organization what the organic movement tends to form, but besides, also by a forced inequality between the matters which are assimilated and those which are dissipated by losses, this function at a certain term of the duration of life causes a progressive deterioration of the organs, so that as a necessary consequence it inevitably causes death; "3. That the property of the movement of the fluids in the parts which contain them is to break out passages, places of deposit, and outlets; to there create canals and consequently different organs; to cause these canals, as well as the organs, to vary on account of the diversity both of the movements and of the nature of the fluids which give rise to them; finally to enlarge, elongate, to gradually divide and solidify [the walls of] these canals and these organs by the matters which form and incessantly separate the fluids which are there in movement, and one part of which is assimilated and added to the organs, while the other is rejected and cast out; "4. That the state of organization in each organism has been gradually acquired by the progress of the influences of the movement of fluids, and by those changes that these fluids have there continually undergone in their nature and their condition through the habitual succession of their losses and of their renewals; "5. That each organization and each form acquired by this course of things and by the circumstances which there have concurred, were preserved and transmitted successively by generation [heredity] until new modifications of these organizations and of these forms have been acquired by the same means and by new circumstances; "6. Finally, that from the uninterrupted concurrence of these causes or from these laws of nature, together with much time and with an almost inconceivable diversity of influential circumstances, organic beings of all the orders have been successively formed. "Considerations so extraordinary, relatively to the ideas that the vulgar have generally formed on the nature and origin of living bodies, will be naturally regarded by you as stretches of the imagination unless I hasten to lay before you some observations and facts which supply the most complete evidence. "From the point of view of knowledge based on observation the philosophic naturalist feels convinced that it is in that which is called the lowest classes of the two organic kingdoms--_i.e._, in those which comprise the most simply organized beings--that we can collect facts the most luminous and observations the most decisive on the _production_ and the reproduction of the living beings in question; on the causes of the formation of the organs of these wonderful beings; and on those of their developments, of their diversity and their multiplicity, which increase with the concourse of generations, of times, and of influential circumstances. "Hence we may be assured that it is only among the singular beings of these lowest classes, and especially in the lowest orders of these classes, that it is possible to find on both sides the primitive germs of life, and consequently the germs of the most important faculties of animality and vegetality." _Modification of the organization from one end to the other of the animal chain._ "One is forced," he says, "to recognize that the totality of existing animals constitute _a series of groups_ forming a true chain, and that there exists from one end to the other of this chain a gradual modification in the structure of the animals composing it, as also a proportionate diminution in the number of faculties of these animals from the highest to the lowest (the first germs), these being without doubt the form with which nature began, with the aid of much time and favorable circumstances, to form all the others." He then begins with the mammals and descends to molluscs, annelids, and insects, down to the polyps, "as it is better to proceed from the known to the unknown;" but farther on (p. 38) he finally remarks: "Ascend from the most simple to the most compound, depart from the most imperfect animalcule and ascend along the scale up to the animal richest in structure and faculties; constantly preserve the order of relation in the group, then you will hold the true thread which connects all the productions of nature; you will have a just idea of its progress, and you will be convinced that the most simple of its living productions have successively given existence to all the others. "_The series which constitutes the animal scale resides in the distribution of the groups, and not in that of the individuals and species._ "I have already said[166] that by this shaded graduation in the complication of structure I do not mean to speak of the existence of a linear and regular series of species or even genera: such a series does not exist. But I speak of a quite regularly graduated series in the principal groups, _i.e._, in the principal system of organizations known, which give rise to classes and to great families, series most assuredly existing both among animals and plants, although in the consideration of genera, and especially in that of species, it offers many lateral ramifications whose extremities are truly isolated points. "However, although there has been denied, in a very modern work, the existence in the animal kingdom of a single series, natural and at the same time graduated, in the composition of the organization of beings which it comprehends, series in truth necessarily formed of groups subordinated to each other as regards structure and not of isolated species or genera, I ask where is the well-informed naturalist who would now present a different order in the arrangement of the twelve classes of the animal kingdom of which I have just given an account? "I have already stated what I think of this view, which has seemed sublime to some moderns, and indorsed by _Professor Hermann_." Each distinct group or mass of forms has, he says, its peculiar system of essential organs, but each organ considered by itself does not follow as regular a course in its degradations (modifications). "Indeed, the least important organs, or those least essential to life, are not always in relation to each other in their improvement or their degradation; and an organ which in one species is atrophied may be very perfect in another. These irregular variations in the perfecting and in the degradation of non-essential organs are due to the fact that these organs are oftener than the others submitted to the influences of external circumstances, and give rise to a diversity of species so considerable and so singularly ordered that instead of being able to arrange them, like the groups, in a single simple linear series under the form of a regular graduated scale, these very species often form around the groups of which they are part lateral ramifications, the extremities of which offer points truly isolated. "There is needed, in order to change each internal system of organization, a combination of more influential circumstances, and of more prolonged duration than to alter and modify the external organs. "I have observed, however, that, when circumstances demand, nature passes from one system to another without making a leap, provided they are allies. It is, indeed, by this faculty that she has come to form them all in succession, in proceeding from the simple to the more complex. "It is so true that she has the power, that she passes from one system to the other, not only in two different families which are allied, but she also passes from one system to the other in the same individual. "The systems of organization which admit as organs of respiration true lungs are nearer to systems which admit gills than those which require tracheæ. Thus not only does nature pass from gills to lungs in allied classes and families, as seen in fishes and reptiles, but in the latter she passes even during the life of the same individual, which successively possesses each system. We know that the frog in the tadpole state respires by gills, while in the more perfect state of frog it respires by lungs. We never see that nature passes from a system with tracheæ to a system with lungs. "_It is not the organs, i.e., the nature and form of the parts of the body of an animal, which give rise to the special habits and faculties, but, on the contrary, its habits, its mode of life, and the circumstances in which individuals are placed, which have, with time, brought about the form of its body, the number and condition of its organs, finally the faculties which it possesses._ * * * * * "Time and favorable circumstances are the two principal means which nature employs to give existence to all her productions. We know that time has for her no limit, and that consequently she has it always at her disposition. "As to the circumstances of which she has need (_besoin_) and which she employs every day to bring about variations in all that she continues to produce, we can say that they are in her in some degree inexhaustible. "The principal ones arise from the influence of climate, from that of different temperatures, of the atmosphere, and from all environing surroundings (_milieux_); from that of the diversity of places and their situations; from that of the most ordinary habitual movements, of actions the most frequent; finally from that of the means of preservation, of the mode of life, of defence, of reproduction, etc. "Moreover, as the result of these different influences the faculties increase and strengthen themselves by use, diversify themselves by the new habits preserved through long periods, and insensibly the conformation, the consistence--in a word, the nature and state of the parts and also of the organs--consequently participate in all these influences, are preserved and propagate themselves by generation" (_Système des Animaux sans Vertèbres_, p. 12). * * * * * "It is easy for any one to see that the habit of exercising an organ in every living being which has not reached the term of diminution of its faculties not only makes this organ more perfect, but even makes it acquire developments and dimensions which insensibly change it, with the result that with time it renders it very different from the same organ considered in another organism which has not, or has but slightly, exercised it. It is also very easy to prove that the constant lack of exercise of an organ gradually reduces it and ends by atrophying it." Then follow the facts regarding the mole, spalax, ant-eater, and the lack of teeth in birds, the origin of shore birds, swimming birds and perching birds, which are stated farther on. "Thus the efforts in any direction, maintained for a long time or made habitually by certain parts of a living body, to satisfy the needs called out (_exigés_) by nature or by circumstances, develop these parts and cause them to acquire dimensions and a form which they never would have obtained if these efforts had not become an habitual action of the animals which have exercised them. Observations made on all the animals known would furnish examples of this. "When the will determines an animal to any kind of action, the organs whose function it is to execute this action are then immediately provoked by the flowing there of subtile fluids, which become the determining cause of movements which perform the action in question. A multitude of observations support this fact, which now no one would doubt. "It results from this that multiplied repetitions of these acts of organization strengthen, extend, develop, and even create the organs which are there needed. It is only necessary to closely observe that which is everywhere happening in this respect to firmly convince ourselves of this cause of developments and organic changes. "However, each change acquired in an organ by habitual use sufficient to have formed (_opéré_) it is preserved by generation, if it is common to the individuals which unite in the reproduction of their kind. Finally, this change propagates itself and is then handed down (_se passe_) to all the individuals which succeed and which are submitted to the same circumstances, without their having been obliged to acquire it by the means which have really created it. "Besides, in the unions between the sexes the intermixtures between individuals which have different qualities or forms are necessarily opposed to the constant propagation of these qualities and forms. We see that which in man, who is exposed to such different circumstances which influence individuals, prevents the qualities of accidental defects which they have happened to acquire from being preserved and propagated by heredity (_génération_). "You can now understand how, by such means and an inexhaustible diversity of circumstances, nature, with sufficient length of time, has been able to and should produce all these results. "If I should choose here to pass in review all the classes, orders, genera, and species of animals in existence I could make you see that the structure of individuals and their organs, faculties, etc., is solely the result of circumstances to which each species and all its races have been subjected by nature, and of habits that the individuals of this species have been obliged to contract. "The influences of localities and of temperatures are so striking that naturalists have not hesitated to recognize the effects on the structure, the developments, and the faculties of the living bodies subject to them. "We have long known that the animals inhabiting the torrid zone are very different from those which live in the other zones. Buffon has remarked that even in latitudes almost the same the animals of the new continent are not the same as those of the old. "Finally the Count Lacépède, wishing to give to this well-founded fact the precision which he believed it susceptible, has traced twenty-six zoölogical divisions on the dry parts of the globe, and eighteen over the ocean; but there are many other influences than those which depend on localities and temperatures. "Everything tends, then, to prove my assertion--namely, that it is not the form either of the body or of its parts which has given rise to habits and to the mode of life of animals, but, on the contrary, it is the habits, the mode of life, and all the other influential circumstances which have with time produced the form of the bodies and organs of animals. With new forms new faculties have been acquired, and gradually nature has arrived at the state where we actually see it. * * * * * "Finally as it is only at that extremity of the animal kingdom where occur the most simply organized animals that we meet those which may be regarded as the true germs of animality, and it is the same at the same end of the vegetable series; is it not at this end of the scale, both animal and vegetable, that nature has commenced and recommenced without ceasing the first germ of her living production? Who is there, in a word, who does not see that the process of perfection of those of these first germs which circumstances have favored will gradually and after the lapse of time give rise to all the degrees of perfection and of the composition of the organization, from which will result this multiplicity and this diversity of living beings of all orders with which the exterior surface of our globe is almost everywhere filled or covered? "Indeed, if the manner (_usage_) of life tends to develop the organization, and even to form and multiply the organs, as the state of an animal which has just been born proves it, compared to that where it finds itself when it has reached the term where its organs (beginning to deteriorate) cease to make new developments; if, then, each particular organ undergoes remarkable changes, according as it is exercised and according to the manner of which I have shown you some examples, you will understand that in carrying you to the end of the animal chain where are found the most simple organizations, and that in considering among these organizations those whose simplicity is so great that they lie at the very door of the creative power of nature, then this same nature--that is to say, the state of things which exist--has been to form directly the first beginnings of organization; she has been able, consequently, by the manner of life and the aid of circumstances which favor its duration, to progressively render perfect its work, and to carry it to the point where we now see it. "Time is wanting to present to you the series of results of my researches on this interesting subject, and to develop-- "1. What really is life. "2. How nature herself creates the first traces of organization in appropriate groups where it had not existed. "3. How the organic or vital movement is excited by it and held together with the aid of a stimulating and active cause which she has at her disposal in abundance in certain climates and in certain seasons of the year. "4. Finally, how this organic movement, by the influence of its duration and by that of the multitude of circumstances which modify its effects, develops, arranges, and gradually complicates the organs of the living body which possesses them. "Such has been without doubt the will of the infinite wisdom which reigns throughout nature; and such is effectively the order of things clearly indicated by the observation of all the facts which relate to them." (End of the opening discourse.) APPENDIX (p. 141). _On Species in Living Bodies._ "I have for a long time thought that _species_ were constant in nature, and that they were constituted by the individuals which belong to each of them. "I am now convinced that I was in error in this respect, and that in reality only individuals exist in nature. "The origin of this error, which I have shared with many naturalists who still hold it, arises from _the long duration_, in relation to us, _of the same state of things_ in each place which each organism inhabits; but this duration of the same state of things for each place has its limits, and with much time it makes changes in each point of the surface of the globe, which produces changes in every kind of circumstances for the organisms which inhabit it. "Indeed, we may now be assured that nothing on the surface of the terrestrial globe remains in the same state. Everything, after a while, undergoes different changes, more or less prompt, according to the nature of the objects and of circumstances. Elevated areas are constantly being lowered, and the loose material carried down to the lowlands. The beds of rivers, of streams, of even the sea, are gradually removed and changed, as also the climate;[167] in a word, the whole surface of the earth gradually undergoes a change in situation, form, nature, and aspect. We see on every hand what ascertained facts prove; it is only necessary to observe and to give one's attention to be convinced of it. "However, if, relatively to living beings, the diversity of circumstances brings about for them a diversity of habits, a different mode of existence, and, as the result, modifications in their organs and in the shape of their parts, one should believe that very gradually every living body whatever would vary in its organization and its form. "All the modifications that each living being will have undergone as the result of change of circumstances which have influenced its nature will doubtless be propagated by heredity (_génération_). But as new modifications will necessarily continue to operate, however slowly, not only will there continually be found new species, new genera, and even new orders, but each species will vary in some part of its structure and its form. "I very well know that to our eyes there seems in this respect a _stability_ which we believe to be constant, although it is not so truly; for a very great number of centuries may form a period insufficient for the changes of which I speak to be marked enough for us to appreciate them. Thus we say that the flamingo (_Phoenicopterus_) has always had as long legs and as long a neck as have those with which we are familiar; finally, it is said that all animals whose history has been transmitted for 2,000 or 3,000 years are always the same, and have lost or acquired nothing in the process of perfection of their organs and in the form of their different parts. We may be assured that this appearance of _stability_ of things in nature will always be taken for reality by the average of mankind, because in general it judges everything only relatively to itself. "But, I repeat, this consideration which has given rise to the admitted error owes its source to the very great slowness of the changes which have gone on. A little attention given to the facts which I am about to cite will afford the strongest proof of my assertion. "What nature does after a great length of time we do every day by suddenly changing, as regards a living being, the circumstances in which it and all the individuals of its species are placed. "All botanists know that the plants which they transplant from their natal spot into gardens for cultivation there gradually undergo changes which in the end render them unrecognizable. Many plants naturally very hairy, there become glabrous or nearly so; a quantity of those which were procumbent or trailing there have erect stems; others lose their spines or their thorns; finally, the dimensions of parts undergo changes which the circumstances of their new situation infallibly produce. This is so well known that botanists prefer not to describe them, at least unless they are newly cultivated. Is not wheat (_Triticum sativum_) a plant brought by man to the state wherein we actually see it, which otherwise I could not believe? Who can now say in what place its like lives in nature? "To these known facts I will add others still more remarkable, and which confirm the view that change of circumstances operates to change the parts of living organisms. "When _Ranunculus aquatilis_ lives in deep water, all it can do while growing is to make the end of its stalks reach the surface of the water where they flourish. Then all the leaves of the plant are finely cut or pinked.[168] If the same plant grows in shallower water the growth of its stalks may give them sufficient extent for the upper leaves to develop out of the water; then its lower leaves only will be divided into hair-like joints, while the upper ones will be simple, rounded, and a little lobed.[169] This is not all: when the seeds of the same plant fall into some ditch where there is only water or moisture sufficient to make them germinate, the plant develops all its leaves in the air, and then none of them is divided into capillary points, which gives rise to _Ranunculus hederaceus_, which botanists regard as a species. "Another very striking proof of the effect of a change of circumstances on a plant submitted to it is the following: "It is observed that when a tuft of _Juncus bufonius_ grows very near the edge of the water in a ditch or marsh this rush then pushes out filiform stems which lie in the water, are there deformed, becoming disturbed (_traçantes_), proliferous, and very different from that of _Juncus bufonius_ which grows out of water. This plant, modified by the circumstances I have just indicated, has been regarded as a distinct species; it is the _Juncus supinus_ of Rotte.[170] "I could also give citations to prove that the changes of circumstances relative to organisms necessarily change the influences which they undergo on the part of all that which environs them or which acts on them, and so necessarily bring about changes in their size, their shape, their different organs. "Then among living beings nature seems to me to offer in an absolute manner only individuals which succeed one another by generation. "However, in order to facilitate the study and recognition of these organisms, I give the name of _species_ to every collection of individuals which during a long period resemble each other so much in all their parts that these individuals only present small accidental differences which, in plants, reproduction by seeds causes to disappear. "But, besides that at the end of a long period the totality of individuals of such a species change as the circumstances which act on them, those of these individuals which from special causes are transported into very different situations from those where the others occur, and then constantly submitted to other influences--the former, I say, assume new forms as the result of a long habit of this other mode of existence, and then they constitute a new _species_, which comprehends all the individuals which occur in the same condition of existence. We see, then, the faithful picture of that which happened in this respect in nature, and of that which the observation of its acts can alone discover to us." III. _Lamarck's Views on Species, as published in 1803._ In the opening lecture[171] of his course at the Museum of Natural History, delivered in prairial (May 20-June 18), 1803, we have a further statement of the theoretical views of Lamarck on species and their origin. He addresses his audience as "Citoyens," France still being under the _régime_ of the Republic. The brochure containing this address is exceedingly rare, the only copy existing, as far as we know, being in the library of the Museum of Natural History in Paris. The author's name is not even given, and there is no imprint. Lamarck's name, however, is written on the outside of the cover of the copy we have translated. At the end of the otherwise blank page succeeding the last page (p. 46) is printed the words: _Esquisse d'un Philosophie zoologique_, the preliminary sketch, however, never having been added. He begins by telling his hearers that they should not desire to burden their memories with the infinite details and immense nomenclature of the prodigious quantity of animals among which we distinguish an illimitable number of species, "but what is more worthy of you, and of more educational value, you should seek to know the course of nature." "You may enter upon the study of classes, orders, genera, and even of the most interesting species, because this would be useful to you; but you should never forget that all these subdivisions, which could not, however, be well spared, are artificial, and that nature does not recognize any of them." "In the opening lecture of my last year's course I tried to convince you that it is only in the organization of animals that we find the foundation of the natural relations between the different groups, where they diverge and where they approach each other. Finally, I tried to show you that the enormous series of animals which nature has produced presents, from that of its extremities where are placed the most perfect animals, down to that which comprises the most imperfect, or the most simple, an evident modification, though irregularly defined (_nuancé_), in the structure of the organization. "To-day, after having recalled some of the essential considerations which form the base of this great truth; after having shown you the principal means by which nature is enabled to create (_opérer_) her innumerable productions and to vary them infinitely; finally, after having made you see that in the use she has made of her power of generating and multiplying living beings she has necessarily proceeded from the more simple to the more complex, gradually complicating the organization of these bodies, as also the composition of their substance, while also in that which she has done on non-living bodies she has occupied herself unremittingly in the destruction of all preëxistent combinations, I shall undertake to examine under your eyes the great question in natural history--What is a _species_ among organized beings? "When we consider the series of animals, beginning at the end comprising the most perfect and complicated, and passing down through all the degrees of this series to the other end, we see a very evident modification in structure and faculties. On the contrary, if we begin with the end which comprises animals the most simple in organization, the poorest in faculties and in organs--in a word, the most imperfect in all respects--we necessarily remark, as we gradually ascend in the series, a truly progressive complication in the organization of these different animals, and we see the organs and faculties of these beings successively multiplying and diversifying in a most remarkable manner. "These facts once known present truths which are, to some extent, eternal; for nothing here is the product of our imagination or of our arbitrary principles; that which I have just explained rests neither on systems nor on any hypothesis: it is only the very simple result of the observation of nature; hence I do not fear to advance the view that all that one can imagine, from any motives whatever, to contradict these great verities will always be destroyed by the evidence of the facts with which it deals. "To these facts it is necessary to add these very important considerations, which observation has led me to perceive, and the basis of which will always be recognized by those who pay attention to them; they are as follows: "Firstly, the exercise of life, and consequently of organic movement, constitutes its activity, tends, without ceasing, not only to develop and to extend the organization, but it tends besides to multiply the organs and to isolate them in special centres (_foyers_). To make sure whether the exercise of life tends to extend and develop the organization, it suffices to consider the state of the organs of any animal which has just been born, and to compare them in this condition with what they are when the animal has attained the period when its organs cease to receive any new development. Then we will see on what this organic law is based, which I have published in my _Recherches sur les Corps vivans_ (p. 8), _i.e._, that-- "'The special property of movement of fluids in the supple parts of the living body which contain them is to open (_frayer_) there routes, places of deposit and tissues; to create there canals, and consequently different organs; to cause these canals and these organs to vary there by reason of the diversity both of the movements as well as the nature of the fluids which occur there; finally to enlarge, to elongate, to divide and to gradually strengthen (_affermir_) these canals and their organs by the matters which are formed in the fluids in motion, which incessantly separate themselves, and a part of which is assimilated and united with organs while the rest is rejected.' "Secondly, the continual employment of an organ, especially if it is strongly exercised, strengthens this organ, develops it, increases its dimensions, enlarges and extends its faculties. "This second law of effects of exercise of life has been understood for a long time by those observers who have paid attention to the phenomena of organization. "Indeed, we know that all the time that an organ, or a system of organs, is rigorously exercised throughout a long time, not only its power, and the parts which form it, grow and strengthen themselves, but there are proofs that this organ, or system of organs, at that time attracts to itself the principal active forces of the life of the individual, because it becomes the cause which, under these conditions, makes the functions of other organs to be diminished in power. "Thus not only every organ or every part of the body, whether of man or of animals, being for a long period and more vigorously exercised than the others, has acquired a power and facility of action that the same organ could not have had before, and that it has never had in individuals which have exercised less, but also we consequently remark that the excessive employment of this organ diminishes the functions of the others and proportionately enfeebles them. "The man who habitually and vigorously exercises the organ of his intelligence develops and acquires a great facility of attention, of aptitude for thought, etc., but he has a feeble stomach and strongly limited muscular powers. He, on the contrary, who thinks little does not easily, and then only momentarily fixes his attention, while habitually giving much exercise to his muscular organs, has much vigor, possesses an excellent digestion, and is not given to the abstemiousness of the savant and man of letters. "Moreover, when one exercises long and vigorously an organ or system of organs, the active forces of life (in my opinion, the nervous fluid) have taken such a habit of acting (_porter_) towards this organ that they have formed in the individual an inclination to continue to exercise which it is difficult for it to overcome. "Hence it happens that the more we exercise an organ, the more we use it with facility, the more does it result that we perceive the need (_besoin_) of continuing to use it at the times when it is placed in action. So we remark that the habit of study, of application, of work, or of any other exercise of our organs or of any one of our organs, becomes with time an indispensable need to the individual, and often a passion which it does not know how to overcome. "Thirdly, finally, the effort made by necessity to obtain new faculties is aided by the concurrence of favorable circumstances; they create (_créent_) with time the new organs which are adapted (_propres_) to their faculties, and which as the result develop after long use (_qu'en suite un long emploi développe_). "How important is this consideration, and what light it spreads on the state of organization of the different animals now living! "Assuredly it will not be those who have long been in the habit of observing nature, and who have followed attentively that which happens to living individuals (to animals and to plants), who will deny that a great change in the circumstances of their situation and of their means of existence forces them and their race to adopt new habits; it will not be those, I say, who attempt to contest the foundation of the consideration which I have just exposed. "They can readily convince themselves of the solidity of that which I have already published in this respect.[172] "I have felt obliged to recall to you these great considerations, a sketch of which I traced for you last year, and which I have stated for the most part in my different works, because they serve, as you have seen, as a solution of the problem which interests so many naturalists, and which concerns the determination of _species_ among living bodies. "Indeed, if in ascending in the series of animals from the most simply organized animalcule, as from the monad, which seems to be only an animated point, up to the animals the most perfect, or whose structure is the most complicated--in a word, up to animals with mammæ--you observe in the different orders which comprise this great series a gradation, shaded (_nuancé_), although irregular, in the composition of the organization and in the increasing number of faculties, is it not evident that in the case where nature would exert some active power on the existence of these organized bodies she has been able to make them exist only by beginning with the most simple, and that she has been able to form directly among the animals only that which I call the rough sketches or germs (_ébauches_) of animality--that is to say, only these animalcules, almost invisible and to some extent without consistence, that we see develop spontaneously and in an astonishing abundance in certain places and under certain circumstances, while only in contrary circumstances are they totally destroyed? "Do we not therefore perceive that by the action of the laws of organization, which I have just now indicated, and by that of different means of multiplication which are due to them (_qui en dérivent_), nature has in favorable times, places, and climates multiplied her first germs (_ébauches_) of animality, given place to developments of their organizations, rendered gradually greater the duration of those which have originally descended from them, and increased and diversified their organs? Then always preserving the progress acquired by the reproductions of individuals and the succession of generations, and aided by much time and by a slow but constant diversity of circumstances, she has gradually brought about in this respect the state of things which we now observe. "How grand is this consideration, and especially how remote is it from all that is generally thought on this subject! Moreover, the astonishment which its novelty and its singularity may excite in you requires that at first you should suspend your judgment in regard to it. But the observation which establishes it is now on record (_consignée_), and the facts which support it exist and are incessantly renewed; however, as they open a vast field to your studies and to your own researches, it is to you yourselves that I appeal to pronounce on this great subject when you have sufficiently examined and followed all the facts which relate to it. "If among living bodies there are any the consideration of whose organization and of the phenomena which they produce can enlighten us as to the power of nature and its course relatively to the existence of these bodies, also as to the variations which they undergo, we certainly have to seek for them in the lowest classes of the two organic kingdoms (the animals and the plants). It is in the classes which comprise the living bodies whose organization is the least complex that we can observe and bring together facts the most luminous, observations the most decisive on the origin of these bodies, on their reproduction and their admirable diversification, finally on the formation and the development of their different organs, the whole process being aided by the concurrence of generations, of time, and of circumstances. "It is, indeed, among living bodies the most multiplied, the most numerous in nature, the most prompt and easy to regenerate themselves, that we should seek the most instructive facts bearing on the course of nature and on the means she has employed to create her innumerable productions. In this case we perceive that, relatively to the animal kingdom, we should chiefly give our attention to the invertebrate animals, because their enormous multiplicity in nature, the singular diversity of their systems of organization and of their means of multiplication, their increasing simplification, and the extreme fugacity of those which compose the lowest orders of these animals, show us much better than the others the true course of nature, and the means which she has used and which she is still incessantly employing to give existence to all the living bodies of which we have knowledge. "Her course and her means are without doubt the same for the production of the different plants which exist. And, indeed, though it is not believed, as some naturalists have wrongly held, but without proof, that plants are bodies more simple in organization than the most simple animals, it is a veritable error which observation plainly denies. "Truly, vegetable substance is less surcharged with constituent principles than any animal substance whatever, or at least most of them, but the substance of a living body and the organization of these bodies are two very different things. But there is in plants, as in animals, a true gradation in organization from the plant simplest in organization and parts up to plants the most complex in structure and with the most diversified organs. "If there is some approach, or at least some comparison to make between vegetables and animals, this can only be by opposing plants the most simply organized, like fungi and algæ, to the most imperfect animals like the polyps, and especially the amorphous polyps, which occur in the lowest order. "At present we clearly see that in order to bring about the existence of animals of all the classes, of all the orders, and of all the genera, nature has had to begin by giving existence to those which are the most simple in organization and lacking most in organs and faculties, the frailest in constituency, the most ephemeral, the quickest and easiest to multiply; and we shall find in the _amorphous_ or _microscopic polyps_ the most striking examples of this simplification of organization, and the indication that it is solely among them that occur the astonishing germs of animality. "At present we only know the principal law of the organization, the power of the exercise of the functions of life, the influence of the movement of fluids in the supple parts of organic bodies, and the power which the regenerations have of conserving the progress acquired in the composition of organs. "At present, finally, relying on numerous observations, seeing that with the aid of much time, of changes in local circumstances, in climates, and consequently in the habits of animals, the progression in the complication of their organization and in the diversity of their parts has gradually operated (_a dû s'opérer_) in a way that all the animals now known have been successively formed such as we now see them, it becomes possible to find the solution of the following question: "What is a _species_ among living beings? "All those who have much to do with the study of natural history know that naturalists at the present day are extremely embarrassed in defining what they mean by the word species. "In truth, observation for a long time has shown us, and shows us still in a great number of cases, collections of individuals which resemble each other so much in their organization and by the _ensemble_ of their parts that we do not hesitate to regard these collections of similar individuals as constituting so many species. "From this consideration we call _species_ every collection of individuals which are alike or almost so, and we remark that the regeneration of these individuals conserves the species and propagates it in continuing successively to reproduce similar individuals. "Formerly it was supposed that each species was immutable, as old as nature, and that she had caused its special creation by the Supreme Author of all which exists. "But we can impose on him laws in the execution of his will, and determine the mode which he has been pleased to follow in this respect, so it is only in this way that he permits us to recognize it by the aid of observation. Has not his infinite power created an order of things which successively gives existence to all that we see as well as to all that which exists and which we do not know? "Assuredly, whatever has been his will, the omnipotence of his power is always the same; and in whatever way this supreme will has been manifested, nothing can diminish its greatness. As regards, then, the decrees of this infinite wisdom, I confine myself to the limits of a simple observer of nature. Then, if I discover anything in the course that nature follows in her creations, I shall say, without fear of deceiving myself, that it has pleased its author that she possesses this power. "The idea that was held as to species among living bodies was quite simple, easy to grasp, and seemed confirmed by the constancy in the similar form of the individuals which reproduction or generation perpetuated. There still occur among us a very great number of these pretended species which we see every day. "However, the farther we advance in the knowledge of the different organized bodies with which almost every part of the surface of the globe is covered, the more does our embarrassment increase in determining what should be regarded as species, and the greater is the reason for limiting and distinguishing the genera. "As we gradually gather the productions of nature, as our collections gradually grow richer, we see almost all the gaps filled up, and our lines of demarcation effaced. We find ourselves compelled to make an arbitrary determination, which sometimes leads us to seize upon the slightest differences between varieties to form of them the character of that which we call species, and sometimes one person designates as a variety of such a species individuals a little different, which others regard as constituting a particular species. "I repeat, the richer our collections become, the more numerous are the proofs that all is more or less shaded (_nuancé_), that the remarkable differences become obliterated, and that the more often nature leaves it at our disposal to establish distinctions only minute, and in some degree trivial peculiarities. "But some genera among animals and plants are of such an extent, from the number of species they contain, that the study and the determination of these species are now almost impossible. The species of these genera, arranged in series and placed together according to their natural relations, present, with those allied to them, differences so slight that they shade into each other; and because these species are in some degree confounded with one another they leave almost no means of determining, by expression in words, the small differences which distinguish them. "There are also those who have been for a long time, and strongly, occupied with the determination of the species, and who have consulted rich collections, who can understand up to what point species, among living bodies, merge one into another (_fondent les unes dans les autres_), and who have been able to convince themselves, in the regions (_parties_) where we see isolated species, that this is only because there are wanting other species which are more nearly related, and which we have not yet collected. "I do not mean to say by this that the existing animals form a very simple series, one everywhere equally graduated; but I say that they form a branching series, irregularly graduated, and which has no discontinuity in its parts, or which at best has not always had, if it is true that it is to be found anywhere (_s'il est vrai qu'il s'en trouve quelque part_). It results from this that the species which terminates each branch of the general series holds a place at least on one side apart from the other allied species which intergrade with them. Behold this state of things, so well known, which I am now compelled to demonstrate. "I have no need (_besoin_) of any hypothesis or any supposition for this: I call to witness all observing naturalists. "Not only many genera, but entire orders, and some classes even, already present us with portions almost complete of the state of things which I have just indicated. "However, when in this case we have arranged the species in series, and they are all well placed according to their natural relations, if you select one of them, and it results in making a leap (_saut pardessus_) over to several others, you take another one of them a little less remote; these two species, placed in comparison, will then present the greatest differences from each other. It is thus that we had begun to regard most of the productions of nature which occur at our door. Then the generic and specific distinctions were very easy to establish. But now that our collections are very much richer, if you follow the series that I have cited above, from the species that you first chose up to that which you took in the second place, and which is very different from the first, you have passed from shade to shade without having remarked any differences worth noticing. "I ask what experienced zoölogist or botanist is there who has not thoroughly realized that which I have just explained to you? "Or how can one study, or how can one be able to determine in a thorough way the species, among the multitude of known polyps of all orders of radiates, worms, and especially of insects, where the simple genera of Papilio, Phalæna, Noctua, Tinea, Musca, Ichneumon, Curculio, Capricorn, Scarabæus, Cetonia, etc., etc., already contain so many closely allied species which shade into each other, are almost confounded one with another? What a host of molluscan shells exist in every country and in all seas which elude our means of distinction, and exhaust our resources in this respect! Ascend to the fishes, to the reptiles, to the birds, even to the mammals, and you will see, except the lacunæ which are still to be filled, everywhere shadings which take place between allied species, even the genera, and where after the most industrious study we fail to establish good distinctions. Does not botany, which considers the other series, comprising the plants, offer us, in its different parts, a state of things perfectly similar? In short, what difficulties do not arise in the study and in the determination of species in the genera Lichena, Fucus, Carex, Poa, Piper, Euphorbia, Erica, Hieracium, Solanum, Geranium, Mimosa, etc., etc.? "When these genera were established but a small number of species were known, and then it was easy to distinguish them; but at present almost all the gaps between them are filled, and our specific differences are necessarily minute and very often insufficient. "From this state of things well established we see what are the causes which have given rise to them; we see whether nature possesses the means for this, and if observation has been able to give us our explanation of it. "A great many facts teach us that gradually as the individuals of one of our species change their situation, climate, mode of life, or habits, they thus receive influences which gradually change the consistence and the proportions of their parts, their form, their faculties, even their organization; so that all of them participate eventually in the changes which they have undergone. "In the same climate, very different situations and exposures at first cause simple variations in the individuals which are found exposed there; but, as time goes on, the continual differences of situation of individuals of which I have spoken, which live and successively reproduce in the same circumstances, give rise among them to differences which are, in some degree, essential to their being, in such a way that at the end of many successive generations these individuals, which originally belonged to another species, are at the end transformed into a new species, distinct from the other. "For example, if the seeds of a grass, or of every other plant natural to a humid field, should be transplanted, by an accident, at first to the slope of a neighboring hill, where the soil, although more elevated, would yet be quite cool (_frais_) so as to allow the plant to live, and then after having lived there, and passed through many generations there, it should gradually reach the poor and almost arid soil of a mountain side--if the plant should thrive and live there and perpetuate itself during a series of generations, it would then be so changed that the botanists who should find it there would describe it as a separate species. "The same thing happens to animals which circumstances have forced to change their climate, manner of living, and habits; but for these the influences of the causes which I have just cited need still more time than in the case of plants to produce the notable changes in the individuals, though in the long run, however, they always succeed in bringing them about. "The idea of defining under the word _species_ a collection of similar individuals which perpetuate the same by generation, and which have existed thus as anciently as nature, implies the necessity that the individuals of one and the same species cannot mix, in their acts of generation, with the individuals of a different species. Unfortunately observation has proved, and still proves every day, that this consideration has no basis; for the hybrids, very common among plants, and the unions which are often observed between the individuals of very different species among animals, have made us perceive that the limits between these species, supposed to be constant, are not so rigid as is supposed. "In truth, nothing often results from these singular unions, especially when they are very incongruous, as the individuals which result from them are usually sterile; but also, when the disparities are less great, it is known that the drawbacks (_défauts_) with which it has to do no longer exist. However, this means alone suffices to gradually create the varieties which have afterwards arisen from races, and which, with time, constitute that which we call _species_. "To judge whether the idea which is formed of species has any real foundation, let us return to the considerations which I have already stated; they are, namely-- "1. That all the organic bodies of our globe are veritable productions of nature, which she has created in succession at the end of much time. "2. That in her course nature has begun, and begins anew every day, by forming the simplest organic bodies, and that she directly forms only these--that is to say, only these first primitive germs (_ébauches_) of organization, which have been badly characterized by the expression of "spontaneous generations" (_qu'on a désignées mal-à-propos par l'expression de Générations spontanées_). "3. That the first germs (_ébauches_) of the animals and plants were formed in favorable places and circumstances. The functions of life beginning and an organic movement established, these have necessarily gradually developed the organs, so that after a time and under suitable circumstances they have been differentiated, as also the different parts (_elles les ont diversifiés ainsi qui les parties_). "4. That the power of increase in each portion of organic bodies being inherited at the first production (_effets_) of life, it has given rise to different modes of multiplication and of regeneration of individuals; and in that way the progress acquired in the composition of the organization and in the forms and the diversity of the parts has been preserved. "5. That with the aid of sufficient time, of circumstances which have been necessarily favorable, of changes that all parts of the surface of the globe have successively undergone in their condition--in a word, with the power that new situations and new habits have in modifying the organs of bodies endowed with life--all those which now exist have been imperceptibly formed such as we see them. "6. Finally, that according to a similar order of things, living beings, having undergone each of the more or less great changes in the condition of their organization and of their parts, that which is designated as a species among them has been insensibly and successively so formed, can have only a relative constancy in its condition, and cannot be as ancient as nature. "But, it will be said, when it is necessary to suppose that, with the aid of much time and of an infinite variation in circumstances, nature has gradually formed the different animals that we know, would we not be stopped in this supposition by the sole consideration of the admirable diversity which we observe in the instinct of different animals, and by that of the marvels of all sorts which their different kinds of industry present? "Will one dare to carry the spirit of system (_porter l'esprit de système_) to the point of saying that it is nature, and she alone, which creates this astonishing diversity of means, of ruses, of skill, of precautions, of patience, of which the industry of animals offers us so many examples! What we observe in this respect in the class of insects alone, is it not a thousand times more than is necessary to compel us to perceive that the limits of the power of nature by no means permit her herself to produce so many marvels, and to force the most obstinate philosophy to recognize that here the will of the supreme author of all things has been necessary, and has alone sufficed to cause the existence of so many admirable things? "Without doubt one would be rash, or rather wholly unreasonable, to pretend to assign limits to the power of the first author of all things; and by that alone no one can dare to say that this infinite power has not been able to will that which nature herself shows us she has willed. "This being so, if I discover that nature herself brings about or causes all the wonders just cited; that she creates the organization, the life, even feeling; that she multiplies and diversifies, within limits which are not known to us, the organs and faculties of organic bodies the existence of which she sustains or propagates; that she has created in animals by the single way of _need_, which establishes and directs the habits, the source of all actions, from the most simple up to those which constitute _instinct_, industry, finally reason, should I not recognize in this power of nature--that is to say, of existing things--the execution of the will of its sublime author, who has been able to will that it should have this power? Shall I any the less wonder at the omnipotence of the power of the first cause of all things, if it has pleased itself that things should be thus, than if by so many (separate) acts of his omnipotent will he should be occupied and occupy himself still continually with details of all the special creations, all the variations, and all the developments and perfections, all the destructions and all the renewals--in a word, with all the changes which are in general produced in things which exist? "But I intend to prove in my 'Biologie' that nature possesses in her _faculties_ all that is necessary to have to be able herself to produce that which we admire in her works; and regarding this subject I shall then enter into sufficient details which I am here obliged to omit.[173] "However, it is still objected that all we see stated regarding the state of living bodies are unalterable conditions in the preservation of their form, and it is thought that all the animals whom history has transmitted to us for two or three thousand years have always remained the same, and have lost nothing nor acquired anything in the perfecting of their organs and in the form of their parts. "While this apparent stability has for a long time been accepted as true, it has just been attempted to establish special proofs in a report on the collections of natural history brought from Egypt by the citizen Geoffroy." Quotes three paragraphs in which the reporters (Cuvier and Geoffroy St. Hilaire) say that the mummied animals of Thebes and Memphis are perfectly similar to those of to-day. Then he goes on to say: "I have seen them, these animals, and I believe in the conformity of their resemblance with the individuals of the same species which live to-day. Thus the animals which the Egyptians worshipped and embalmed two or three thousand years ago are still in every respect similar to those which actually live in that country. "But it would be assuredly very singular that this should be otherwise; for the position of Egypt and its climate are still or very nearly the same as at former times. Therefore the animals which live there have not been compelled to change their habits. "There is, then, nothing in the observation which has just been reported which should be contrary to the considerations which I have expressed on this subject; and which especially proves that the animals of which it treats have existed during the whole period of nature. It only proves that they have existed for two or three thousand years; and every one who is accustomed to reflect, and at the same time to observe that which nature shows us of the monuments of its antiquity, readily appreciates the value of a duration of two or three thousand years in comparison with it. "Hence, as I have elsewhere said, it is sure that this appearance of the stability of things in nature will always be mistaken by the average of mankind for the reality; because in general people only judge of everything relatively to themselves. "For the man who observes, and who in this respect only judges from the changes which he himself perceives, the intervals of these changes are _stationary conditions_ (_états_) which should appear to be limitless, because of the brevity of life of the individuals of his species. Thus, as the records of his observations and the notes of facts which he has consigned to his registers only extend and mount up to several thousands of years (three to five thousand years), which is an infinitely small period of time relatively to those which have sufficed to bring about the great changes which the surface of the globe has undergone, everything seems _stable_ to him in the planet which he inhabits, and he is inclined to reject the monuments heaped up around him or buried in the earth which he treads under his feet, and which surrounds him on all sides.[174] * * * * * "It seems to me [as mistaken as] to expect some small creatures which only live a year, which inhabit some corner of a building, and which we may suppose are occupied with consulting among themselves as to the tradition, to pronounce on the duration of the edifice where they occur: and that going back in their paltry history to the twenty-fifth generation, they should unanimously decide that the building which serves to shelter them is eternal, or at least that it has always existed; because it has always appeared the same to them; and since they have never heard it said that it had a beginning. Great things (_grandeurs_) in extent and in duration are relative.[175] "When man wishes to clearly represent this truth he will be reserved in his decisions in regard to stability, which he attributes in nature to the state of things which he observes there.[176] "To admit the insensible change of species, and the modifications which individuals undergo as they are gradually forced to vary their habits or to contract new ones, we are not reduced to the unique consideration of too small spaces of time which our observations can embrace to permit us to perceive these changes; for, besides this induction, a quantity of facts collected for many years throws sufficient light on the question that I examine, so that does not remain undecided; and I can say now that our sciences of observation are too advanced not to have the solution sought for made evident. "Indeed, besides what we know of the influences and the results of heteroclite fecundations, we know positively to-day that a forced and long-sustained change, both in the habits and mode of life of animals, and in the situation, soil, and climate of plants, brings about, after a sufficient time has elapsed, a very remarkable change in the individuals which are exposed to them. "The animal which lives a free, wandering life on plains, where it habitually exercises itself in running swiftly; the birds whose needs (_besoins_) require them unceasingly to traverse great spaces in the air, finding themselves enclosed, some in the compartments of our menageries or in our stables, and others in our cages or in our poultry yards, are submitted there in time to striking influences, especially after a series of regenerations under the conditions which have made them contract new habits. The first loses in large part its nimbleness, its agility; its body becomes stouter, its limbs diminish in power and suppleness, and its faculties are no longer the same. The second become clumsy; they are unable to fly, and grow more fleshy in all parts of their bodies. "Behold in our stout and clumsy horses, habituated to draw heavy loads, and which constitute a special race by always being kept together--behold, I say, the difference in their form compared with those of English horses, which are all slender, with long necks, because for a long period they have been trained to run swiftly: behold in them the influence of a difference of habit, and judge for yourselves. You find them, then, such as they are in some degree in nature. You find there our cock and our hen in the condition we have [made] them, as also the mixed races that we have formed by mixed breeding between the varieties produced in different countries, or where they were so in the state of domesticity. You find there likewise our different races of domestic pigeons, our different dogs, etc. What are our cultivated fruits, our wheat, our cabbage, our lettuce, etc., etc., if they are not the result of changes which we ourselves have effected in these plants, in changing by our culture the conditions of their situation? Are they now found in this condition in nature? To these incontestable facts add the considerations which I have discussed in my _Recherches sur les Corps vivans_ (p. 56 _et suiv._), and decide for yourselves. "Thus, among living bodies, nature, as I have already said, offers only in an absolute way individuals which succeed each other genetically, and which descend one from the other. So the _species_ among them are only relative, and only temporary. "Nevertheless, to facilitate the study and the knowledge of so many different bodies it is useful to give the name of _species_ to the entire collection of individuals which are alike, which reproduction perpetuates in the same condition as long as the conditions of their situation do not change enough to make their habits, their character, and their form vary. "Such is, citizens, the exact sketch of that which goes on in nature since she has existed, and of that which the observation of her acts has alone enabled us to discover. I have fulfilled my object if, in presenting to you the results of my researches and of my experience, I have been able to disclose to you that which in your studies of this kind deserves your special attention. "You now doubtless conceive how important are the considerations which I have just exposed to you, and how wrong you would be if, in devoting yourself to the study of animals or of plants, you should seek to see among them only the multiplied distinctions that we have been obliged to establish; in a word, if you should confine yourselves to fixing in your memory the variable and indefinite nomenclature which is applied to so many different bodies, instead of studying Nature herself--her course, her means, and the constant results that she knows how to attain." On the next fly page are the following words: _Esquisse d'une Philosophie zoologique_. IV. _Lamarck's Views as published in 1806._[177] "Those who have observed much and have consulted the great collections, have been able to convince themselves that as gradually as the circumstances of their habitat, of exposure to their surroundings, of climate, food, mode of living, etc., have changed, the characters of size, form, of proportion between the parts, of color, of consistence, of duration, of agility, and of industry have proportionately changed. "They have been able to see, as regards the animals, that the more frequent and longer sustained use of any organ gradually strengthens this organ, develops it, enlarges it, and gives it a power proportional to the length of time it has been used; while the constant lack of use of such an organ insensibly weakens it, causes it to deteriorate, progressively diminishes its faculties, and tends to make it waste away.[178] "Finally, it has been remarked that all that nature has made individuals to acquire or lose by the sustained influence of circumstances where their race has existed for a long time, she has preserved by heredity in the new individuals which have originated from them (_elle le conserve par la génération aux nouveaux individus qui en proviennent_). These verities are firmly grounded, and can only be misunderstood by those who have never observed and followed nature in her operations. "Thus we are assured that that which is taken for _species_ among living bodies, and that all the specific differences which distinguish these natural productions, have no absolute _stability_, but that they enjoy only a relative _stability_; which it is very important to consider in order to fix the limits which we must establish in the determination of that which we must call _species_. "It is known that different places change in nature and character by reason of their position, their 'composition' [we should say geological structure or features], and their climate; that which is easily perceived in passing over different places distinguished by special characteristics; behold already a cause of variation for the natural productions which inhabit these different places. But that which is not sufficiently known, and even that which people refuse to believe, is that each place itself changes after a time, in exposure, in climate, in nature, and in character, although with a slowness so great in relation to our period of time that we attribute to it a perfect _stability_. "Now, in either case, these changed places proportionately change the circumstances relative to the living bodies which inhabit them, and these produce again other influences on those same bodies. "We see from this that if there are extremes in these changes there are also gradations (_nuances_), that is to say, steps which are intermediate, and which fill up the interval; consequently there are also gradations in the differences which distinguish that which we call _species_. "Indeed, as we constantly meet with such shades (or intermediate steps) between these so-called _species_, we find ourselves forced to descend to the minutest details to find any distinctions; the slightest peculiarities of form, of color, of size, and often even of differences only perceived in the aspect of the individual compared with other individuals which are related to it the more by their relations, are seized upon by naturalists to establish specific differences; so that, the slightest varieties being reckoned as species, our catalogues of species grow infinitely great, and the name of the productions of nature of the most interest to us are, so to speak, buried in these enormous lists, become very difficult to find, because now the objects are mostly only determined by characters which our senses can scarcely enable us to perceive. "Meanwhile we should remember that nothing of all this exists in nature; that she knows neither classes, orders, genera, nor species, in spite of all the foundation which the portion of the natural series which our collection contains has seemed to afford them; and that of organic or living bodies there are, in reality, only individuals, and among different races which gradually pass (_nuancent_) into all degrees of organization" (p. 14). On p. 70 he speaks of the animal chain from monad to man, ascending from the most simple to the most complex. The monad is the most simple, the most like a germ of living bodies, and from its nature passes to the volvoces, proteus, vibrios; from them nature arrives at the production of "polypes rotifères"--and then at "Radiaires," worms, Arachnida, Crustacea, and Cirrhipedes. FOOTNOTES: [162] _Discours d'ouverture du Cours de Zoologie donné dans le Muséum national d'Histoire naturelle, le 21 floréal, an 8 de la République_ (1800). Floréal is the name adopted by the National Convention for the eighth month of the year. In the years of the Republic 1 to 7 it extended from April 20 to May 19 inclusive, and in the years 8 to 13 from April 21 to May 20 (_Century Cyclopedia of Names_). The lecture, then, in which Lamarck first presented his views was delivered on some day between April 21 and May 20, 1800. [163] Lamarck by the word _génération_ implies heredity. He nowhere uses the word _hérédité_. [164] "L'oiseau que le besoin attire sur l'eau pour y trouver la proie qui le fait vivre, écarte les doigts de ses pieds lorsqu'il veut frapper l'eau et se mouvoir à sa surface" (p. 13). If the word _veut_ has suggested the doctrine of appetency in meaning has been pushed too far by the critics of Lamarck. [165] This he already touched upon in his _Mémoires de Physique et d'Histoire naturelle_ (p. 342). [166] _Système des Animaux sans Vertèbres_, pp. 16 and 17. [167] I have cited the incontestable proofs in my _Hydrogéologie_, and I have the conviction that one day all will be compelled to accept these great truths. [168] _Ranunculus aquaticus capillaceus_ (Tournef., p. 291). [169] _Ranunculus aquaticus_ (folio rotundo et capillaceo, Tournef., p. 291). [170] _Gramen junceum_, etc. (Moris, hist. 3, sec. 8, t. 9, f. 4). [171] _Discours d'ouverture d'un Cours de Zoologie, prononcé en prairial, an XI, au Muséum d'Histoire naturelle, sur la question, Qu'est-ce que l'espèce parmi les corps vivans?_ (1803). [172] _Recherches sur l'Organisation des Corps vivans_, p. 9. [173] "See at the end of this discourse the sketch of a _Philosophie zoologique_ relative to this subject." [This sketch was not added--only the title at the end of the book.] [174] See the _Annales du Muséum d'Hist. nat._, IV^e cahier. 1., 1802, pp. 302, 303: _Mémoires sur les Fossiles des Environs de Paris_, etc. He repeats in his _Discours_ what he wrote in 1802 in the _Annales_. [175] _Ibid._ This is repeated from the article in the _Annales_. [176] _Ibid._ "See my _Recherches sur les Corps vivans_" (Appendix, p. 141). [177] _Discours d'Ouverture du Cours des Animaux sans Vertèbres, prononcé dans le Muséum d'Histoire naturelle en mai 1806._ (No imprint. 8^o, pp. 108.) Only the most important passages are here translated. [178] "We know that all the forms of organs compared to the uses of these same organs are always perfectly adapted. But there is a common error in this connection, since it is thought that the forms of organs have caused their functions (_en ont amené l'emploi_), whereas it is easy to demonstrate by observation that it is the uses (_usages_) which have given origin to the forms of organs." CHAPTER XVII THE "PHILOSOPHIE ZOOLOGIQUE" Lamarck's mature views on the theory of descent comprise a portion of his celebrated _Philosophie zoologique_. We will let him tell the story of creation by natural causes so far as possible in his own words. In the _avertissement_, or preface, he says that his experience has led him to realize that a body of precepts and of principles relating to the study of animals and even applicable to other parts of the natural sciences would now be useful, our knowledge of zoölogical facts having, for about thirty years, made considerable progress. After referring to the differences in structure and faculties characterizing animals of different groups, he proceeds to outline his theory, and begins by asking: "How, indeed, can I consider the singular modification in the structure of animals, as we glance over the series from the most perfect to the least perfect, without asking how we can account for a fact so positive and so remarkable--a fact attested to me by so many proofs? Should I not think that nature has successively produced the different living beings by proceeding from the most simple to the most compound; because in ascending the animal scale from the most imperfect up to the most perfect, the organization perfects itself and becomes gradually complicated in a most remarkable way?" This leads him to consider what is life, and he remarks (p. xv.) that it does not exist without external stimuli. The conditions necessary for the existence of life are found completely developed in the simplest organization. We are then led to inquire how this organization, by reason of certain changes, can give rise to other organisms less simple, and finally originate creatures becoming gradually more complicated, as we see in ascending the animal scale. Then employing the two following considerations, he believes he perceives the solution of the problem which has occupied his thoughts. He then cites as factors (1) use and disuse; (2) the movement of internal fluids by which passages are opened through the cellular tissue in which they move, and finally create different organs. Hence the _movement of fluids in the interior of animals_, and the _influence of new circumstances_ as animals gradually expose themselves to them in spreading into every inhabitable place, are the two general causes which have produced the different animals in the condition we now see them. Meanwhile he perceived the importance of the preservation by heredity, though he nowhere uses that word, in the new individuals reproduced of everything which the results of the life and influencing circumstances had caused to be acquired in the organization of those which have transmitted existence to them. In the _Discours préliminaire_, referring to the _progression_ in organization of animals from the simplest to man, as also to the successive acquisition of different special organs, and consequently of as many faculties as new organs obtained, he remarks: "Then we can perceive how needs (_besoins_), at the outset reduced to nullity, and of which the number gradually increases, have produced the inclination (_penchant_) to actions fitted to satisfy it; how the actions, becoming habitual and energetic, have caused the development of the organs which execute them; how the force which excites the organic movements may, in the simplest animals, be outside of them and yet animate them; how, then, this force has been transported and fixed in the animal itself; finally, how it then has become the source of sensibility, and in the end that of acts of intelligence. "I shall add that if this method had been followed, then _sensation_ would not have been regarded as the general and immediate cause of organic movements, and it would not have been said that life is a series of movements which are executed in virtue of sensations received by different organs; or, in other words, that all the vital movements are the product of impressions received by the sensitive parts.[179] "This cause seems, up to a certain point, established as regards the most perfect animals; but had it been so relatively to all living beings, they should all be endowed with the power of sensation. But it cannot be proved that this is the case with plants, and it cannot likewise be proved that it is so with all the animals known. "But nature in creating her organisms has not begun by suddenly establishing a faculty so eminent as that of sensation: she has had the means of producing this faculty in the imperfect animals of the first classes of the animal kingdom," referring to the Protozoa. But she has accomplished this gradually and successively. "Nature has progressively created the different special organs, also the faculties which animals enjoy." He remarks that though it is indispensable to classify living forms, yet that our classifications are all artificial; that species, genera, families, orders, and classes do not exist in nature--only the individuals really exist. In the third chapter he gives the old definition of species, that they are fixed and immutable, and then speaks of the animal series, saying: "I do not mean by this to say that the existing animals form a very simple series, and especially evenly graduated; but I claim that they form a branched series,[180] irregularly graduated, and which has no discontinuity in its parts, or which, at least, has not always had, if it is true that, owing to the extinction of some species, there are some breaks. It follows that the _species_ which terminates each branch of the general series is connected at least on one side with other _species_ which intergrade with it" (p. 59). He then points out the difficulty of determining what are species in certain large genera, such as Papilio, Ichneumon, etc. How new species arise is shown by observation. "A number of facts teaches us that in proportion as the individuals of one of our species are subjected to changes in situation, climate, mode of life or habits, they thereby receive influences which gradually change the consistence and the proportions of their parts, their form, their faculties, even their structure; so that it follows that all of them after a time participate in the changes to which they have been subjected. "In the same climate very different situations and exposures cause simple variations in the individuals occurring there; but, after the lapse of time, the continual differences of situation of the individuals of which I speak, which live and successively reproduce under the same circumstances, produce differences in them which become, in some degree, essential to their existence, so that at the end of many successive generations these individuals, which originally belonged to another species, became finally transformed into a new species distinct from the other. "For example, should the seeds of a grass or of any other plant natural to a moist field be carried by any means at first to the slope of a neighboring hill, where the soil, although more elevated, will yet be sufficiently moist to allow the plant to live there, and if it results, after having lived there and having passed through several generations, that it gradually reaches the dry and almost arid soil of a mountain side; if the plant succeeds in living there, and perpetuates itself there during a series of generations, it will then be so changed that any botanists who should find it there would make a distinct species of it. "The same thing happens in the case of animals which circumstances have forced to change in climate, mode of life, and habits; but in their case the influences of the causes which I have just cited need still more time than the plants to bring about notable changes in the individuals. "The idea of embracing, under the name of _species_, a collection of like individuals which are perpetuated by generation, and which have remained the same as long as nature has endured, implies the necessity that the individuals of one and the same species should not cross with individuals of a different species. "Unfortunately observation has proved, and still proves every day, that this consideration is unfounded; for hybrids, very common among plants, and the pairings which we often observe between the individuals of very different _species_ of animals, have led us to see that the limits between these supposed constant species are not so fixed as has been imagined. "In truth, nothing often results from these singular unions, especially if they are very ill-assorted, and then the individuals which do result from them are usually infertile; but also, when the disparities are less great, we know that the default in question does not occur. "But this cause only suffices to create, step by step, varieties which finally become races, and which, with time, constitute what we call _species_. "To decide whether the idea which is formed of the _species_ has any real foundation, let us return to the considerations which I have already explained; they lead us to see: "1. That all the organized bodies of our globe are true productions of Nature, which she has successively formed after the lapse of much time; "2. That, in her course. Nature has begun, and begins over again every day, to form the simplest organisms, and that she directly creates only those, namely, which are the first germs (_ébauches_) of organization, which are designated by the expression of _spontaneous generations_; "3. That the first germs of the animal and plant having been formed in appropriate places and circumstances, the faculties of a beginning life and of an organic movement established, have necessarily gradually developed the organs, and that with time they have diversified them, as also the parts; "4. That the power of growth in each part of the organized body being inherent in the first created forms of life, it has given rise to different modes of multiplication and of regeneration of individuals; and that consequently the progress acquired in the composition of the organization and in the shape and diversity of the parts has been preserved; "5. That with the aid of sufficient time, of circumstances which have been necessarily favorable, of changes of condition that every part of the earth's surface has successively undergone--in a word, by the power which new situations and new habits have of modifying the organs of living beings, all those which now exist have been gradually formed such as we now see them; "6. Finally, that, according to a similar order of things, living beings having undergone each of the more or less great changes in the condition of their structure and parts, that which we call a _species_ among them has been gradually and successively so formed, having only a relative constancy in its condition, and not being as old as Nature herself. "But, it will be said, when it is supposed that by the aid of much time and of an infinite variation in circumstances, Nature has gradually formed the different animals known to us, shall we not be stopped in this supposition by the simple consideration of the admirable diversity which we observe in the _instincts_ of different animals, and by that of the marvels of every kind presented by their different kinds of _industry_? "Shall we dare to extend the spirit of system so far as to say that it is Nature who has herself alone created this astonishing diversity of means, of contrivances, of skill, of precautions, of patience, of which the _industry_ of animals offers us so many examples? What we observe in this respect in the simple class of _insects_, is it not a thousand times more than sufficient to make us realize that the limit to the power of Nature in nowise permits her to herself produce so many marvels, but to force the most obstinate philosopher to recognize that here the will of the Supreme Author of all things has been necessary, and has alone sufficed to create so many admirable things? "Without doubt, one would be rash or, rather, wholly insensate, to pretend to assign limits to the power of the first Author of all things; but, aside from that, no one could dare to say that this infinite power could not will that which Nature even shows us it has willed"[181] (p. 67). Referring to the alleged proof of the fixity of species brought forward by Cuvier in the _Annales du Muséum d'Histoire naturelle_ (i., pp. 235 and 236) that the mummied birds, crocodiles, and other animals of Egypt present no differences from those now living, Lamarck says: "It would assuredly be very singular if it were otherwise, because the position of Egypt and its climate are still almost exactly what they were at that epoch. Moreover, the birds which live there still exist under the same circumstances as they were then, not having been obliged to change their habits. "Moreover, who does not perceive that birds, which can so easily change their situation and seek places which suit them are less subject than many other animals to the variations of local circumstances, and hence less restricted in their habits." He adds the fact that the animals in question have inhabited Egypt for two or three thousand years, and not necessarily from all time, and that this is not time enough for marked changes. He then gives the following definition of species, which is the best ever offered: "Species, then, have only a relative stability, and are invariable only temporarily." "Yet, to facilitate the study and knowledge of so many different organisms it is useful to give the name of _species_ to every similar collection of similar individuals which are perpetuated by heredity (_génération_) in the same condition, so long as the circumstances of their situation do not change enough to render variable their habits, character, and form." He then discusses fossil species in the way already described in Chapter III. (p. 75). The subject of the checks upon over-population by the smaller and weaker animals, or the struggle for existence, is thus discussed in Chapter IV.: "Owing to the extreme multiplication of the small species, and especially of the most imperfect animals, the multiplicity of individuals might be prejudicial to the preservation of the species, to that of the progress acquired in the improvement of the organization--in a word, to the general order, if nature had not taken precautions to keep this multiplication within due limits over which she would never pass. "Animals devour one another, except those which live only on plants; but the latter are exposed to being devoured by the carnivorous animals. "We know that it is the strongest and the best armed which devour the weaker, and that the larger kinds devour the smaller. Nevertheless, the individuals of a single species rarely devour each other: they war upon other races.[182] "The multiplication of the small species of animals is so considerable, and the renewals of their generations are so prompt, that these small species would render the earth uninhabitable to the others if nature had not set a limit to their prodigious multiplication. But since they serve as prey for a multitude of other animals, as the length of their life is very limited, and as the lowering of the temperature kills them, their numbers are always maintained in proper proportions for the preservation of their races and that of others. "As to the larger and stronger animals, they would be too dominant and injure the preservation of other races if they should multiply in too great proportions. But their races devouring each other, they would only multiply slowly and in a small number at a time; this would maintain in this respect the kind of equilibrium which should exist. "Finally, only man, considered separately from all which is characteristic of him, seems capable of multiplying indefinitely, because his intelligence and his resources secure him from seeing his increase arrested by the voracity of any animals. He exercises over them such a supremacy that, instead of fearing the larger and stronger races of animals, he is thus rather capable of destroying them, and he continually checks their increase. "But nature has given him numerous passions, which, unfortunately, developing with his intelligence, thus place a great obstacle to the extreme multiplication of the individuals of his species. "Indeed, it seems as if man had taken it upon himself unceasingly to reduce the number of his fellow-creatures; for never, I do not hesitate to say, will the earth be covered with the population that it could maintain. Several of its habitable parts would always be alternately very sparsely populated, although the time for these alternate changes would be to us measureless. "Thus by these wise precautions everything is preserved in the established order; the changes and perpetual renewals which are observable in this order are maintained within limits over which they cannot pass; the races of living beings all subsist in spite of their variations; the progress acquired in the improvement of the organization is not lost; everything which appears to be disordered, overturned, anomalous, reënters unceasingly into the general order, and even coöperates with it; and especially and always the will of the sublime Author of nature and of all existing things is invariably executed" (pp. 98-101). In the sixth chapter the author treats of the degradation and simplification of the structure from one end to the other of the animal series, proceeding, as he says, inversely to the general order of nature, from the compound to the more simple. Why he thus works out this idea of a general degradation is not very apparent, since it is out of tune with his views, so often elsewhere expressed, of a progressive evolution from the simple to the complex, and to his own classification of the animal kingdom, beginning as it does with the simplest forms and ending with man. Perhaps, however, he temporarily adopts the prevailing method of beginning with the highest forms in order to bring out clearly the successive steps in inferiority or degradation presented in descending the animal scale. We will glean some passages of this chapter which bear on his theory of descent. Speaking of the different kinds of aquatic surroundings he remarks: "In the first place it should be observed that in the waters themselves she [Nature] presents considerably diversified circumstances; the fresh waters, marine waters, calm or stagnant waters, running waters or streams, the waters of warm climates, those of cold regions, finally those which are shallow and those which are very deep, offer many special circumstances, each of which acts differently on the animals living in them. Now, in a degree equal to the make-up of the organization, the races of animals which are exposed to either of these circumstances have been submitted to special influences and have been diversified by them." He then, after referring to the general degradation of the Batrachians, touches upon the atrophy of legs which has taken place in the snakes: "If we should consider as a result of _degradation_ the loss of legs seen in the snakes, the _Ophidia_ should be regarded as constituting the lowest order of reptiles; but it would be an error to admit this consideration. Indeed, the serpents being animals which, in order to hide themselves, have adopted the habit of gliding directly along the ground, their body has lengthened very considerably and disproportionately to its thickness. Now, elongated legs proving disadvantageous to their necessity of gliding and hiding, very short legs, being only four in number, since they are vertebrate animals, would be incapable of moving their bodies. Thus the habits of these animals have been the cause of the disappearance of their legs, and yet the _batrachians_, which have them, offer a more degraded organization, and are nearer the fishes" (p. 155). Referring on the next page to the fishes, he remarks:-- "Without doubt their general form, their lack of a constriction between the head and the body to form a neck, and the different fins which support them in place of legs, are the results of the influence of the dense medium which they inhabit, and not that of the _dégradation_ of their organization. But this modification (_dégradation_) is not less real and very great, as we can convince ourselves by examining their internal organs; it is such as to compel us to assign to the fishes a rank lower than that of the reptiles." He then states that the series from the lamprey and fishes to the mammals is not a regularly gradated one, and accounts for this "because the work of nature has been often changed, hindered, and diverted in direction by the influences which singularly different, even contrasted, circumstances have exercised on the animals which are there found exposed in the course of a long series of their renewed generations." Lamarck thus accounts for the production of the radial symmetry of the medusæ and echinoderms, his _Radiaires_. At the present day this symmetry is attributed perhaps more correctly to their more or less fixed mode of life. "It is without doubt by the result of this means which nature employs, at first with a feeble energy with _polyps_, and then with greater developments in the _Radiata_, that the radial form has been acquired; because the subtile ambient fluids, penetrating by the alimentary canal, and being expansive, have been able, by an incessantly renewed repulsion from the centre towards every point of the circumference, to give rise to this radiated arrangement of parts. "It is by this cause that, in the Radiata, the intestinal canal, although still very imperfect, since more often it has only a single opening, is yet complicated with numerous radiating vasculiform, often ramified, appendages. "It is, doubtless, also by this cause that in the soft Radiates, as the medusæ, etc., we observe a constant isochronic movement, movement very probably resulting from the successive intermissions between the masses of subtile fluids which penetrate into the interior of these animals and those of the same fluids which escape from it, often being spread throughout all their parts. "We cannot say that the isochronic movements of the soft Radiates are the result of their respiration; for below the vertebrate animals nature does not offer, in that of any animal, these alternate and measured movements of inspiration and expiration. Whatever may be the respiration of Radiates, it is extremely slow, and is executed without perceptible movements" (p. 200). _The Influence of Circumstances on the Actions and Habits of Animals._ It is in Chapter VII. that the views of Lamarck are more fully presented than elsewhere, and we therefore translate all of it as literally as possible, so as to preserve the exact sense of the author. "We do not here have to do with a line of argument, but with the examination of a positive fact, which is more general than is supposed, and which has not received the attention it deserves, doubtless because, very often, it is quite difficult to discover. This fact consists in the influence which circumstances exert on the different organisms subjected to them. "In truth, for a long time there has been noticed the influence of different states of our organization on our character, our propensities (_penchants_), our actions, and even our ideas; but it seems to me that no one has yet recognized that of our actions and of our habits on our organization itself. Now, as these actions and these habits entirely depend on the circumstances in which we habitually find ourselves, I shall try to show how great is the influence which these circumstances exercise on the general form, on the condition of the parts, and even on the organization of living bodies. It is therefore this very positive fact which is to be the subject of this chapter. "If we have not had numerous occasions to plainly recognize the effects of this influence on certain organisms which we have transported under entirely new and different circumstances, and if we had not seen these effects and the changes resulting from them produced, in a way, under our very eyes, the important fact in question would have always remained unknown. "The influence of circumstances is really continuously and everywhere active on living beings, but what renders it difficult for us to appreciate this influence is that its effects only become sensible or recognizable (especially in the animals) at the end of a long period. "Before stating and examining the proofs of this fact, which deserves our attention, and which is very important for a zoölogical philosophy, let us resume the thread of the considerations we had begun to discuss. "In the preceding paragraph we have seen that it is now an incontrovertible fact that, in considering the animal scale in a sense the inverse of that of nature, we find that there exists in the groups composing this scale a continuous but irregular modification (_dégradation_) in the organization of animals which they comprise, an increasing simplification in the organization of these organisms; finally, a proportionate diminution in the number of faculties of these beings. "This fact once recognized may throw the greatest light on the very order which nature has followed in the production of all the existing animals; but it does not show why the structure of animals in its increasing complexity from the more imperfect up to the most perfect offers only an irregular gradation, whose extent presents a number of anomalies or digressions which have no appearance of order in their diversity. "Now, in seeking for the reason of this singular irregularity in the increasing complexity of organization of animals, if we should consider the outcome of the influences that the infinitely diversified circumstances in all parts of the globe exercise on the general form, the parts, and the very organization of these animals, everything will be clearly explained. "It will, indeed, be evident that the condition in which we find all animals is, on one side, the result of the increasing complexity of the organization which tends to form a regular gradation, and, on the other, that it is that of the influences of a multitude of very different circumstances which continually tend to destroy the regularity in the gradations of the increasing complexity of the organization. "Here it becomes necessary for me to explain the meaning I attach to the expression _circumstances influencing the form and structure of animals_--namely, that in becoming very different they change, with time, both their form and organization by proportionate modifications. "Assuredly, if these expressions should be taken literally, I should be accused of an error; for whatever may be the circumstances, they do not directly cause any modification in the form and structure of animals. "But the great changes in the circumstances bring about in animals great changes in their needs, and such changes in their needs necessarily cause changes in their actions. Now, if the new needs become constant or very permanent, the animals then assume new _habits_, which are as durable as the needs which gave origin to them. We see that this is easily demonstrated and even does not need any explanation to make it clearer. "It is then evident that a great change in circumstances having become constant in a race of animals leads these animals into new habits. "Now, if new circumstances, having become permanent in a race of animals, have given to these animals new _habits_--that is to say, have led them to perform new actions which have become habitual--there will from this result the use of such a part by preference to that of another, and in certain cases the total lack of use of any part which has become useless. "Nothing of all this should be considered as a hypothesis or as a mere peculiar opinion; they are, on the contrary, truths which require, in order to be made evident, only attention to and the observation of facts. "We shall see presently by the citation of known facts which prove it, on one side that the new wants, having rendered such a part necessary, have really by the result of efforts given origin to this part, and that as the result of its sustained use it has gradually strengthened it, developed, and has ended in considerably increasing its size; on the other side we shall see that, in certain cases, the new circumstances and new wants having rendered such a part wholly useless, the total lack of use of this part has led to the result that it has gradually ceased to receive the development which the other parts of the animal obtain; that it gradually becomes emaciated and thin; and that finally, when this lack of use has been total during a long time, the part in question ends in disappearing. All this is a positive fact; I propose to give the most convincing proofs. "In the plants, where there are no movements, and, consequently, no habits properly so called, great changes in circumstances do not bring about less great differences in the development of their parts; so that these differences originate and develop certain of them, while they reduce and cause several others to disappear. But here everything operates by the changes occurring in the nutrition of the plant, in its absorptions and transpirations, in the amount of heat, light, air, and humidity which it habitually receives; finally, in the superiority that certain of the different vital movements may assume over others. "Between individuals of the same species, some of which are constantly well nourished, and in circumstances favorable to their entire development, while the others live under reversed circumstances, there is brought about a difference in the condition of these individuals which gradually becomes very remarkable. How many examples could I not cite regarding animals and plants, which would confirm the grounds for this view! Now, if the circumstances remain the same, rendering habitual and constant the condition of individuals badly fed, diseased, or languishing, their internal organization becomes finally modified, and reproduction between the individuals in question preserves the acquired modifications, and ends in giving rise to a race very distinct from that of the individuals which unceasingly meet with circumstances favorable to their development. "A very dry spring-time is the cause of the grass of a field growing very slowly, remaining scraggy and puny, flowering and fruiting without growing much. "A spring interspersed with warm days and rainy days makes the same grass grow rapidly, and the harvest of hay is then excellent. "But if any cause perpetuates the unfavorable circumstances surrounding these plants, they vary proportionally, at first in their appearance and general condition, and finally in several particulars of their characters. "For example, if some seed of any of the grasses referred to should be carried into an elevated place, on a dry and stony greensward much exposed to the winds, and should germinate there, the plant which should be able to live in this place would always be badly nourished, and the individuals reproduced there continuing to exist under these depressing circumstances, there would result a race truly different from that living in the field, though originating from it. The individuals of this new race would be small, scraggy, and some of their organs, having developed more than others, would then offer special proportions. "Those who have observed much, and who have consulted the great collections, have become convinced that in proportion as the circumstances of habitat, exposure, climate, food, mode of life, etc., come to change, the characters of size, form, proportion between the parts, color, consistence, agility, and industry in the animals change proportionally. "What nature accomplishes after a long time, we bring about every day by suddenly changing, in the case of a living plant, the circumstances under which it and all the individuals of its species exist. "All botanists know that the plants which they transplant from their birthplace into gardens for cultivation gradually undergo changes which at last render them unrecognizable. Many plants naturally very hairy then become glabrous, or almost so; many of those which were creeping and trailing, then become erect; others lose their spines or their prickles; others still, from the woody and perennial condition which their stem possesses in a warm climate, pass, in our climate, into an herbaceous condition, and among these several are nothing more than annual plants; finally, the dimensions of their parts themselves undergo very considerable changes. These effects of changes of circumstances are so well known that botanists prefer not to describe garden plants, at least only those which have been newly cultivated. "Is not cultivated wheat (_Triticum sativum_) only a plant brought by man into the condition in which we actually see it? Who can tell me in what country such a plant lives in a state of nature--that is to say, without being there the result of its culture in some neighboring region? "Where occur in nature our cabbage, lettuce, etc., in the condition in which we see them in our kitchen-gardens? Is it not the same as regards a number of animals which domestication has changed or considerably modified? "What very different races among our fowls and domestic pigeons, which we have obtained by raising them in different circumstances and in different countries, and how vainly do we now endeavor to rediscover them in nature! "Those which are the least changed, without doubt by a more recent process of domestication, and because they do not live in a climate which is foreign to them, do not the less possess, in the condition of some of their parts, great differences produced by the habits which we have made them contract. Thus our ducks and our domestic geese trace back their type to the wild ducks and geese; but ours have lost the power of rising into the high regions of the air, and of flying over extensive regions; finally, a decided change has been wrought in the state of their parts compared with that of animals of the race from which they have descended. "Who does not know that such a native bird, which we raise in a cage and which lives there five or six years in succession, and after that replaced in nature--namely, set free--is then unable to fly like its fellows which have always been free? The slight change of circumstance operating on this individual has only diminished its power of flight, and doubtless has not produced any change in the shape of its parts. But if a numerous series of generations of individuals of the same race should have been kept in captivity for a considerable time, there is no doubt but that even the form of the parts of these individuals would gradually undergo notable changes. For a much stronger reason, if, instead of a simple captivity constantly maintained over them, this circumstance had been at the same time accompanied by a change to a very different climate, and if these individuals by degrees had been habituated to other kinds of food, and to other kinds of movements to obtain it; certainly these circumstances, united and becoming constant, would insensibly form a new and special race. "Where do we find, in nature, this multitude of races of _dogs_, which, as the result of domesticity to which we have reduced these animals, have been brought into their present condition? Where do we find these bull-dogs, greyhounds, water spaniels, spaniels, pug-dogs, etc., etc., races which present among themselves much greater differences than those which we admit to be specific in wild animals of the same genus? "Without doubt, a primitive single race, very near the wolf, if it is not itself the true type, has been submitted by man, at some period, to the process of domestication. This race, which then offered no difference between its individuals, has been gradually dispersed by man into different countries, with different climates; and after a time these same individuals, having undergone the influences of their habitats, and of the different habits they were obliged to contract in each country, have undergone remarkable changes, and have formed different special races. Now, the man who, for commercial reasons or from interests of any other kind, travels a very great distance, having carried into a densely populated place, as for example a great capital, different races of dogs originated in some very distant country, then the increase of these races by heredity (_génération_) has given rise successively to all those we now know. "The following fact proves, as regards plants, how a change in any important circumstance leads to a change in the parts of their organisms. "So long as _Ranunculus aquatilis_ is submerged in the water, its leaves are all finely incised and the divisions hair-like; but when the stalks of this plant reach the surface of the water, the leaves which grow out in the air are wider, rounded, and simply lobed. If some feet from the same plant the roots succeed in pushing into a soil only damp, without being submerged, their stalks then are short, none of their leaves are divided into capillary divisions, which gives rise to _Ranunculus hederaceus_, which the botanists regard as a species whenever they meet with it. "There is no doubt that as regards animals important changes in the circumstances under which they are accustomed to live do not produce alteration in their organs; for here the changes are much slower in operating than in plants, and, consequently, are to us less marked, and their cause less recognizable. "As to the circumstances which have so much power in modifying the organs of living beings, the most influential are, doubtless, the diversity of the surroundings in which they live; but besides this there are many others which, in addition, have a considerable influence in the production of the effects in question. "It is known that different localities change in nature and quality owing to their position, their nature, and their climate, as is easily seen in passing over different places distinguished by special features; hence we see a cause of variation for the animals and plants which live in these different places. But what we do not sufficiently know, and even what we generally refuse to believe, is that each place itself changes with time in exposure, in climate, in nature, and quality, although with a slowness so great in relation to our own continuance that we attribute to it a perfect stability. "Now, in either case, these changed localities proportionally change the circumstances relative to the organisms which inhabit them, and the latter then give rise to other influences bearing on these same beings. "We perceive from this that, if there are extremes in these changes, there are also gradations--namely, degrees which are intermediate and which fill the interval. Consequently there are also gradations in the differences which distinguish what we call _species_. "It is then evident that the whole surface of the earth offers, in the nature and situation of the matters which occupy its different points, a diversity of circumstances which is throughout in relation with that of the forms and parts of animals, independent of the special diversity which necessarily results from the progress of the composition of organization in each animal. "In each locality where animals can live, the circumstances which establish there an order of things remain for a long time the same, and really change there only with a slowness so great that man cannot directly notice them. He is obliged to consult monuments to recognize that in each one of these places the order of things that he discovers there has not always been the same, and to perceive that it will change more. "The races of animals which live in each of these places should, then, retain their customary habits there also for a long time; hence to us seems an apparent constancy of races which we call _species_--constancy which has originated among us the idea that these races are as ancient as nature. "But in the different points of the earth's surface which can be inhabited, nature and the situation of the places and climates constitute there, for the animals as for the plants, _different circumstances_ of all sorts of degrees. The animals which inhabit these different places should then differ from each other, not only on account of the state of nature of the organization in each race, but, besides, by reason of the habits that the individuals of each race there are forced to have; so, in proportion as he traverses the larger parts of the earth's surface the observing naturalist sees circumstances changing in a manner somewhat noticeable; he constantly sees that the species change proportionately in their characters. "Now, the true order of things necessary to consider in all this consists in recognizing: "1. That every slight change maintained under the circumstances where occur each race of animals, brings about in them a real change in their wants. "2. That every change in the wants of animals necessitates in them other movements (_actions_) to satisfy the new needs, and consequently other habits. "3. That every new want necessitating new actions to satisfy it, demands of the animal which feels it both the more frequent use of such of its parts of which before it made less use, which develops and considerably enlarges them, and the use of new parts which necessity has caused to insensibly develop in it by the effects of its inner feelings; which I shall constantly prove by known facts. "Thus, to arrive at a knowledge of the true causes of so many different forms and so many different habits of which the known animals offer us examples, it is necessary to consider that circumstances infinitely diversified, but all slowly changing, into which the animals of each race are successively thrown, have caused, for each of them, new wants and necessarily changes in their habits. Moreover, this truth, which cannot be denied, being once recognized, it will be easy to see how the new needs have been able to be satisfied, and the new habits formed, if any attention be given to the two following laws of nature, which observation always confirms: "_First Law._ "In every animal which has not exceeded the term of its development, the more frequent and sustained use of any organ gradually strengthens this organ, develops and enlarges it, and gives it a strength proportioned to the length of time of such use; while the constant lack of use of such an organ imperceptibly weakens it, causes it to become reduced, progressively diminishes its faculties, and ends in its disappearance. "_Second Law._ "Everything which nature has caused individuals to acquire or lose by the influence of the circumstances to which their race may be for a long time exposed, and consequently by the influence of the predominant use of such an organ, or by that of the constant lack of use of such part, it preserves by heredity (_génération_) and passes on to the new individuals which descend from it, provided that the changes thus acquired are common to both sexes, or to those which have given origin to these new individuals. "These are the two fundamental truths which can be misunderstood only by those who have never observed or followed nature in its operations, or only by those who allow themselves to fall into the error which I have combated. "Naturalists having observed that the forms of the parts of animals compared with the uses of these parts are always in perfect accord, have thought that the forms and conditions of parts have caused the function; but this is a mistake, for it is easy to demonstrate by observation that it is, on the contrary, the needs and uses of organs which have developed these same parts, which have even given origin to them where they did not exist, and which consequently have given rise to the condition in which we observe them in each animal. "If this were not so, it would have been necessary for nature to have created for the parts of animals as many forms as the diversity of circumstances in which they have to live had required, and that these forms and also the circumstances had never varied. "This is certainly not the existing order of things, and if it were really such, we should not have the race-horses of England; we should not have our great draft horses, so clumsy and so different from the first named, for nature herself has not produced their like; we should not, for the same reason, have terrier dogs with bow legs, greyhounds so swift in running, water-spaniels, etc.; we should not have tailless fowls, fantail pigeons, etc.; finally, we could cultivate the wild plants as much as we pleased in the rich and fertile soil of our gardens without fearing to see them change by long culture. "For a long time we have felt the force of the saying which has passed into the well-known proverb--_habits form a second nature_. "Assuredly, if the habits and nature of each animal can never vary, the proverb is false, has no foundation, and does not apply to the instances which led to its being spoken. "If we should seriously consider all that I have just stated, it might be thought that I had good reason when in my work entitled _Recherches sur les Corps vivans_ (p. 50) I established the following proposition: "'It is not the organs--that is to say, the nature and form of the parts of the body of an animal--which have given rise to its habits and its special faculties; but it is, on the contrary, its habits, its manner of life, and the circumstances in which are placed the individuals from which it originates, which have, with time, brought about the form of its body, the number and condition of its organs, finally, the faculties which it enjoys.' "If we weigh this proposition, and if we recall all the observations which nature and the state of things continually lead us to do, then its importance and its solidity will become more evident. "Time and favorable circumstances are, as I have already said, the two principal means which nature employs to give existence to all her productions: we know that time for her has no limits, and that consequently it is ever at her disposal. "As to the circumstances of which she has need, and which she uses still daily to cause variations in all that she continues to produce, we can say that they are, in some degree, for her inexhaustible. "The principal circumstances arise from the influence of climate; from those of different temperatures of the atmosphere, and from all the environing media; from that of the diversity of different localities and their situation; from that of habits, the ordinary movements, the most frequent actions; finally, from that of means of preservation, of mode of living, of defence, of reproduction, etc. "Moreover, owing to these diverse influences, the faculties increase and become stronger by use, become differentiated by the new habits preserved for long ages, and insensibly the organization, the consistence--in a word, the nature and condition of parts, as also of the organs--participate in the results of all these influences, become preserved, and are propagated by generation. "These truths, which are only the results of the two natural laws above stated, are in every case completely confirmed by facts; they clearly indicate the course of nature in all the diversity of its products. "But instead of contenting ourselves with generalities which might be considered as hypothetical, let us directly examine the facts, and consider, in the animals, the result of the use or disuse of their organs on the organs themselves, according to the habits that each race has been compelled to contract. "I shall now attempt to prove that the constant lack of exercise of organs at first diminishes their faculties, gradually impoverishes them, and ends by making them disappear, or even causing them to be atrophied, if this lack of use is perpetuated for a very long time through successive generations of animals of the same race. "I shall next prove that, on the contrary, the habit of exercising an organ, in every animal which has not attained the limit of the diminution of its faculties, not only perfects and increases the faculties of this organ, but, besides, enables it to acquire developments and dimensions which insensibly change it; so that with time it renders it very different from the same organ in another animal which exercises it much less. "_The lack of use of an organ, become constant by the habits formed, gradually impoverishes this organ, and ends by causing it to disappear and even to destroy it._ "As such a proposition can only be admitted on proof, and not by its simple announcement, let us prove it by the citation of the leading known facts on which it is based. "The vertebrate animals, whose plan of organization is in all nearly the same, although they offer much diversity in their parts, have jaws armed with _teeth_; moreover, those among them which circumstances have placed in the habit of swallowing their food without previous _mastication_ are exposed to the result that their teeth become undeveloped. These teeth, then, either remain concealed between the bony edges of the jaws, without appearing above, or even their gums are found to have been atrophied. "In the baleen whales, which have been supposed to be completely deprived of teeth, M. Geoffroy has found them concealed in the jaws of the _foetus_ of this animal. This professor has also found in the birds the groove where the teeth should be situated; but they are no longer to be seen there. "In the class even of mammals, which comprises the most perfect animals, and chiefly those in which the vertebrate plan of organization is most perfectly carried out, not only the baleen has no usable teeth, but the ant-eater (_Myrmecophaga_) is also in the same condition, whose habit of not masticating its food has been for a long time established and preserved in its race. "The presence of eyes in the head is a characteristic of a great number of different animals, and becomes an essential part of the plan of organization of vertebrates. "Nevertheless the mole, which owing to its habits makes very little use of vision, has only very small eyes, which are scarcely visible, since they exercise these organs to a very slight extent. "The _Aspalax_ of Olivier (_Voyage en Egypte et en Perse_, ii. pl. 28 f. 2), which lives under ground like the mole, and which probably exposes itself still less than that animal to the light of day, has totally lost the power of sight; also it possesses only vestiges of the organ of which it is the seat; and yet these vestiges are wholly concealed under the skin and other parts which cover them, and do not permit the least access to the light. "The _Proteus_, an aquatic reptile allied to the salamander in its structure, and which lives in the dark subterranean waters of deep caves, has, like the _Aspalax_, only vestiges of the organs of sight--vestiges which are covered and concealed in the same manner. "We turn to a decisive consideration relative to this question. "Light does not penetrate everywhere; consequently animals which habitually live in situations where it does not penetrate lack the occasion of exercising the organs of sight, if nature has provided them with them. Moreover, the animals which make part of the plan of organization in which _eyes_ are necessarily present, have originally had them. However, since we find them among those which are deprived of the use of this organ, and which have only vestiges concealed and covered over, it should be evident that the impoverishment and even the disappearance of these organs are the result of a constant lack of exercise. "What proves it is that the organ of _hearing_ is never in this condition, and that we always find it in the animals when the nature of their organization should require its existence; the reason is as follows. "The _cause of sound_, that which, moved by the shock or the vibrations of bodies, transmits to the organ of hearing the impression which it receives, penetrates everywhere, traverses all the media, and even the mass of the densest bodies: from this it results that every animal which makes a part of a plan of organization to which _hearing_ is essential, has always occasion to exercise this organ in whatever situation it lives. So, among the _vertebrate animals_ we see none deprived of their organs of hearing; but in the groups below them, when the same organs are once wanting, we do not again find them. "It is not so with the organ of sight, for we see this organ disappear, reappear, and again disappear, in proportion to the possibility or impossibility of the animal's exercising it. "In the _acephalous molluscs_, the great development of the mantle of these molluscs has rendered their eyes and even their head entirely useless. These organs, also forming a part of a plan of organization which should comprise them, have disappeared and atrophied from constant lack of use. "Finally, it is a part of the plan of organization of _reptiles_, as in other vertebrate animals, to have four legs appended to their skeleton. The serpents should consequently have four, though they do not form the lowest order of reptiles, and are not so near the fishes as the batrachians (the frogs, the salamanders, etc.). "However, the serpents having taken up the habit of gliding along the ground, and of concealing themselves in the grass, their body, owing to continually repeated efforts to elongate itself so as to pass through narrow spaces, has acquired a considerable length disproportionate to its size. Moreover, limbs would have been very useless to these animals, and consequently would not have been employed: because long legs would have interfered with their need of gliding, and very short legs, not being more than four in number, would have been incapable of moving their body. Hence the lack of use of these parts having been constant in the races of these animals, has caused the total disappearance of these same parts, although really included in the plan of organization of the animals of their class. "Many insects which by the natural character of their order, and even of their genus, should have wings, lack them more or less completely from disuse. A quantity of Coleoptera, Orthoptera, Hymenoptera, and of Hemiptera, etc., afford examples; the habits of these animals do not require them to make use of their wings. "But it is not sufficient to give the explanation of the cause which has brought about the condition of the organs of different animals--a condition which we see to be always the same in those of the same species; we must besides observe the changes of condition produced in the organs of one and the same individual during its life, by the single result of a great change in the special habits in the individuals of its species. The following fact, which is one of the most remarkable, will serve to prove the influence of habits on the condition of organs, and show how changes wrought in the habits of an individual, produce the condition of the organs which are brought into action during the exercise of these habits. "M. Tenon, member of the Institute, has given an account to the Class of Sciences, that having examined the intestinal canal of several men who had been hard drinkers all their lives, he had constantly found it to be shortened to an extraordinary extent, compared with the same organ in those not given to such a habit. "We know that hard drinkers, or those who are addicted to drunkenness, take very little solid food, that they eat very lightly, and that the beverage which they take in excess frequently suffices to nourish them. "Moreover, as fluid aliments, especially spirituous liquors, do not remain a long time either in the stomach or in the intestines, the stomach and the remainder of the intestinal canal lose the habit of being distended in intemperate persons, so also in sedentary persons and those engaged in mental labor, who are habituated to take but little food. Gradually and at length their stomach becomes contracted, and their intestines shortened. "We are not concerned here with the shrinkage and shortening produced by a puckering of the parts, which permit ordinary extension, if instead of a continued emptiness these viscera should be filled; the shrinkage and shortening in question are real, considerable, and such that these organs would burst open rather than yield suddenly to the causes which would require ordinary extension. "In circumstances of persons of the same age, compare a man who, in order to devote himself to habitual study and mental work, which have rendered his digestion more difficult, has contracted the habit of eating lightly, with another who habitually takes a good deal of exercise, walks out often, and eats heartily; the stomach of the first will be weakened, and a small quantity of food will fill it, while that of the second will be not only maintained in its ordinary health but even strengthened. "We have here the case of an organ much modified in its dimensions and in its faculties by the single cause of a change in habits during the life of the individual. "_The frequent use of an organ become constant by habit increases the faculties of this organ, even develops it, and enables it to acquire dimensions and a power of action which it does not possess in animals which exercise less._ "We have just said that the lack of employment of an organ which necessarily exists modifies it, impoverishes it, and ends by its disappearing entirely. "I shall now demonstrate that the continued employment of an organ, with the efforts made to draw out its powers under circumstances where it would be of service, strengthens, extends, and enlarges this organ, or creates a new one which can exercise the necessary functions. "The bird which necessity drives to the water to find there prey fitted for its sustenance, opens the digits of its feet when it wishes to strike the water and propel itself along its surface. The skin which unites these digits at their base, by these acts of spreading apart being unceasingly repeated contracts the habit of extending; so that after a while the broad membranes which connect the digits of ducks, geese, etc., are formed as we see them. The same efforts made in swimming--_i.e._, in pushing back the water, in order to advance and to move in this liquid--have likewise extended the membrane situated between the digits of the frogs, the sea-turtles, the otter, beaver, etc. "On the contrary, the bird whose mode of life habituates it to perch on trees, and which is born of individuals who have all contracted this habit, has necessarily the digits of the feet longer and shaped in another way than those of the aquatic animals which I have just mentioned. Its claws, after a while, became elongated, pointed, and curved or hook-like in order to grasp the branches on which the animal often rests. "Likewise we see that the shore bird, which is not inclined to swim, and which moreover has need of approaching the edge of the water to find there its prey, is in continual danger of sinking in the mud. Now, this bird, wishing to act so that its body shall not fall into the water, makes every effort to extend and elongate its legs. It results from this that the long-continued habit that this bird and the others of its race contract, of extending and continually elongating their legs, is the _cause_ of the individuals of this race being raised as if on stilts, having gradually acquired long, naked legs, which are denuded of feathers up to the thighs and often above them (_Système des Animaux sans Vertèbres_, p. 16). "We also perceive that the same bird, wishing to catch fish without wetting its body, is obliged to make continual efforts to lengthen its neck. Now, the results of these habitual efforts in this individual and in those of its race have enabled them, after a time, to singularly elongate them--as, indeed, is proved by the long neck of all shore birds. "If any swimming birds, such as the swan and the goose, whose legs are short, nevertheless have a very long neck, it is because these birds in swimming on the surface of the water have the habit of plunging their head down as far as they can, to catch aquatic larvæ and different animalcules for food, and because they make no effort to lengthen their legs. "When an animal to satisfy its wants makes repeated efforts to elongate its tongue, it will acquire a considerable length (the ant-eater, green wood-pecker); when it is obliged to seize anything with this same organ, then its tongue will divide and become forked. That of the humming-birds, which seize with their tongue, and that of the lizard and serpents, which use it to feel and examine objects in front of them, are proofs of what I advocate. "Wants, always occasioned by circumstances, and followed by sustained efforts to satisfy them, are not limited in results, in modifying--that is to say, in increasing or diminishing--the extent and the faculties of organs; but they also come to displace these same organs when certain of these wants become a necessity. "The fishes which habitually swim in large bodies of water, having need of seeing laterally, have, in fact, their eyes placed on the sides of the head. Their bodies, more or less flattened according to the _species_, have their sides perpendicular to the plane of the water, and their eyes are placed in such a way that there is an eye on each flattened side. But those fishes whose habits place them under the necessity of constantly approaching the shores, and especially the shelving banks or where the slope is slight, have been forced to swim on their flattened faces, so as to be able to approach nearer the edge of the water. In this situation, receiving more light from above than from beneath, and having a special need of being always attentive to what is going on above them, this need has forced one of their eyes to undergo a kind of displacement, and to assume the very singular situation which is familiar to us in the _soles_, _turbots_, _dabs_, etc. (_Pleuronectes_ and _Achirus_). The situation of these eyes is asymmetrical, because this results from an incomplete change. Now, this change is entirely completed in the rays, where the transverse flattening of the body is entirely horizontal, as also the head. Also the eyes of the rays, both situated on the upper side, have become symmetrical. "The serpents which glide along the surface of the ground are obliged chiefly to see elevated objects, or what are above their eyes. This necessity has brought an influence to bear on the situation of the organs of vision in these animals; and, in fact, they have the eyes placed in the lateral and upper parts of the head, so as to easily perceive what is above or at their sides; but they only see for a short distance what is in front of them. Moreover, forced to supply the lack of ability to see and recognize what is in front of their head, and which might injure them, they need only to feel such objects with the aid of their tongue, which they are obliged to dart out with all their power. This habit has not only contributed to render the tongue slender, very long and retractile, but has also led in a great number of species to its division, so as to enable them to feel several objects at once; it has likewise allowed them to form an opening at the end of their head, to enable the tongue to dart out without their being obliged to open their jaws. "Nothing is more remarkable than the result of habits in the herbivorous mammals. "The quadruped to whom circumstances and the wants which they have created have given for a long period, as also to others of its race, the habit of browsing on grass, only walks on the ground, and is obliged to rest there on its four feet the greater part of its life, moving about very little, or only to a moderate extent. The considerable time which this sort of creature is obliged to spend each day to fill itself with the only kind of food which it requires, leads it to move about very little, so that it uses its legs only to stand on the ground, to walk, or run, and they never serve to seize hold of or to climb trees. "From this habit of daily consuming great amounts of food which distend the organs which receive it, and of only moving about to a limited extent, it has resulted that the bodies of these animals are thick, clumsy, and massive, and have acquired a very great volume, as we see in elephants, rhinoceroses, oxen, buffaloes, horses, etc. "The habit of standing upright on their four feet during the greater part of the day to browse has given origin to a thick hoof which envelops the extremity of the digits of their feet; and as their toes are not trained to make any movement, and because they have served no other use than as supports, as also the rest of the leg, the most of them are short, are reduced in size, and even have ended by totally disappearing. Thus in the _pachyderms_, some have five toes enveloped in horn, and consequently their foot is divided into five parts; others have only four, and still others only three. But in the _ruminants_, which seem to be the most ancient of mammals, which are limited only to standing on the ground, there are only two digits on each foot, and only a single one is to be found in the _solipedes_ (the horse, the ass). "Moreover, among these herbivorous animals, and especially among the ruminants, it has been found that from the circumstances of the desert countries they inhabit they are incessantly exposed to be the prey of carnivorous animals, and find safety only in precipitous flight. Necessity has forced them to run swiftly; and from the habit they have thus acquired their body has become slenderer and their limbs much more delicate: we see examples in the antelopes, the gazelles, etc. "Other dangers in our climate to which are continually exposed the deer, the roebuck, the fallow-deer, of perishing from the chase made by man, have reduced them to the same necessity, restrained them to similar habits, and have given rise to the same results. "The ruminating animals only using their legs as supports, and not having strong jaws, which are only exercised in cutting and browsing on grass, can only fight by striking with the head, by directing against each other the _vertex_ of this part. "In their moments of anger, which are frequent, especially among the males, their internal feelings, by their efforts, more strongly urge the fluids toward this part of their head, and it there secretes the corneous matter in some, and osseous matter mixed with corneous matter in others, which gives origin to solid protuberances; hence the origin of horns and antlers, with which most of these animals have the head armed. "As regards habits, it is curious to observe the results in the special form and height of the giraffe (_camelopardalis_); we know that this animal, the tallest of mammals, inhabits the interior of Africa, and that it lives in localities where the earth, almost always arid and destitute of herbage, obliges it to browse on the foliage of trees, and to make continual efforts to reach it. It has resulted from this habit, maintained for a long period in all the individuals of its race, that its forelegs have become longer than the hinder ones, and that its neck is so elongated that the giraffe, without standing on its hind legs, raises its head and reaches six meters in height (almost twenty feet). "Among the birds, the ostriches, deprived of the power of flight, and raised on very long legs, probably owe their singular conformation to analogous circumstances. "The result of habits is as remarkable in the carnivorous mammals as it is in the herbivorous, but it presents effects of another kind. "Indeed, those of these mammals which are habituated, as their race, both to climb as well as to scratch or dig in the ground, or to tear open and kill other animals for food, have been obliged to use the digits of their feet; moreover, this habit has favored the separation of their digits, and has formed the claws with which they are armed. "But among the carnivores there are some which are obliged to run in order to overtake their prey; moreover, since these need and consequently have the habit of daily tearing with their claws and burying them deeply in the body of another animal, to seize and then to tear the flesh, and have been enabled by their repeated efforts to procure for these claws a size and curvature which would greatly interfere in walking or running on stony soil, it has resulted in this case that the animal has been obliged to make other efforts to draw back these too salient and curved claws which would impede it, and hence there has resulted the gradual formation of those special sheaths in which the cats, tigers, lions, etc., withdraw their claws when not in action. "Thus the efforts in any direction whatever, maintained for a long time or made habitually by certain parts of a living body to satisfy necessities called out by nature or by circumstances, develop these parts and make them acquire dimensions and a shape which they never would have attained if these efforts had not become the habitual action of the animals which have exercised them. The observations made on all the animals known will everywhere furnish examples. "Can any of them be more striking than that which the _kangaroo_ offers us? This animal, which carries its young in its abdominal pouch, has adopted the habit of holding itself erect, standing only on its hind feet and tail, and only changing its position by a series of leaps, in which it preserves its erect attitude so as not to injure its young. "Let us see the result: "1. Its fore legs, of which it makes little use, and on which it rests only during the instant when it leaves its erect attitude, have never reached a development proportionate to that of the other parts, and have remained thin, very small, and weak; "2. The hind legs, almost continually in action, both for supporting the body and for leaping, have, on the contrary, obtained a considerable development, and have become very large and strong; "3. Finally, the tail, which we see is of much use in supporting the animal and in the performance of its principal movements, has acquired at its base a thickness and a strength extremely remarkable. "These well-known facts are assuredly well calculated to prove what results from the habitual use in the animals of any organ or part; and if, when there is observed in an animal an organ especially well developed, strong, and powerful, it is supposed that its habitual use has not produced it, that its continual disuse will make it lose nothing, and, finally, that this organ has always been such since the creation of the species to which this animal belongs, I will ask why our domestic ducks cannot fly like wild ducks--in a word, I might cite a multitude of examples which prove the differences in us resulting from the exercise or lack of use of such of our organs, although these differences might not be maintained in the individuals which follow them genetically, for then their products would be still more considerable. "I shall prove, in the second part, that when the will urges an animal to any action, the organs which should execute this action are immediately provoked by the affluence of subtile fluids (the nervous fluid), which then become the determining cause which calls for the action in question. A multitude of observations prove this fact, which is now indisputable. "It results that the multiplied repetitions of these acts of organization strengthen, extend, develop, and even create the organs which are necessary. It is only necessary attentively to observe that which is everywhere occurring to convince ourselves of the well-grounded basis of this cause of organic developments and changes. "Moreover, every change acquired in an organ by a habit of use sufficient to have produced it is then preserved by heredity (_génération_) if it is common to the individuals which, in fecundation, unite in the reproduction of their species. Finally, this change is propagated, and thus is transmitted to all the individuals which succeed and which are submitted to the same circumstances, unless they have been obliged to acquire it by the means which have in reality created it. "Besides, in reproductive unions the crossings between the individuals which have different qualities or forms are necessarily opposed to the continuous propagation of these qualities and these forms. We see that in man, who is exposed to so many diverse circumstances which exert an influence on him, the qualities or the accidental defects which he has been in the way of acquiring, are thus prevented from being preserved and propagated by generation. If, when some particular features of form or any defects are acquired, two individuals under this condition should always pair, they would reproduce the same features, and the successive generations being confined to such unions, a special and distinct race would then be formed. But perpetual unions between individuals which do not have the same peculiarities of form would cause all the characteristics acquired by special circumstances to disappear. "From this we can feel sure that if distances of habitation did not separate men the intermixture by generation would cause the general characteristics which distinguish the different nations to disappear. "If I should choose to pass in review all the classes, all the orders, all the genera, and all the species of animals which exist, I should show that the structure of individuals and their parts, their organs, their faculties, etc., etc., are in all cases the sole result of the circumstances in which each species is found to be subjected by nature and by the habits which the individuals which compose it have been obliged to contract, and which are only the product of a power primitively existing, which has forced the animals into their well-known habits. "We know that the animal called the _ai_, or the sloth (_Bradypus tridactylus_), is throughout life in a condition so very feeble that it is very slow and limited in its movements, and that it walks on the ground with much difficulty. Its movements are so slow that it is thought that it cannot walk more than fifty steps in a day. It is also known that the structure of this animal is in direct relation with its feeble state or its inaptitude for walking; and that should it desire to make any other movements than those which it is seen to make, it could not do it. "Therefore, supposing that this animal had received from nature its well-known organization, it is said that this organization has forced it to adopt the habits and the miserable condition it is in. "I am far from thinking so; because I am convinced that the habits which the individuals of the race of the _ai_ were originally compelled to contract have necessarily brought their organization into its actual state. "Since continual exposure to dangers has at some time compelled the individuals of this species to take refuge in trees and to live in them permanently, and then feed on their leaves, it is evident that then they would give up making a multitude of movements that animals which live on the ground perform. "All the needs of the _ai_ would then be reduced to seizing hold of the branches, to creeping along them or to drawing them in so as to reach the leaves, and then to remain on the tree in a kind of inaction, so as to prevent falling. Besides, this kind of sluggishness would be steadily provoked by the heat of the climate; for in warm-blooded animals the heat urges them rather to repose than to activity. "Moreover, during a long period of time the individuals of the race of the _ai_ having preserved the habit of clinging to trees and of making only slow and slightly varied movements, just sufficient for their needs, their organization has gradually become adapted to their new habits, and from this it will result: "1. That the arms of these animals making continual efforts readily to embrace the branches of trees, would become elongated; "2. That the nails of their digits would acquire much length and a hooked shape, by the continued efforts of the animal to retain its hold; "3. That their digits never having been trained to make special movements, would lose all mobility among themselves, would become united, and would only preserve the power of bending or of straightening out all together; "4. That their thighs, continually embracing both the trunks and the larger branches of trees, would contract a condition of habitual separation which would tend to widen the pelvis and to cause the cotyloid cavities to be directed backward; "5. Finally, that a great number of their bones would become fused, and hence several parts of their skeleton would assume an arrangement and a figure conformed to the habits of these animals, and contrary to what would be necessary for them to have for other habits. "Indeed, this can never be denied, because, in fact, nature on a thousand other occasions shows us, in the power exercised by circumstances on habits, and in that of the influence of habits on forms, dispositions, and the proportion of the parts of animals, truly analogous facts. "A great number of citations being unnecessary, we now see to what the case under discussion is reduced. "The fact is that divers animals have each, according to their genus and their species, special habits, and in all cases an organization which is perfectly adapted to these habits. "From the consideration of this fact, it appears that we should be free to admit either one or the other of the following conclusions, and that only one of them is susceptible of proof. "_Conclusion admitted up to this day_: Nature (or its Author), in creating the animals, has foreseen all the possible kinds of circumstances in which they should live, and has given to each species an unchanging organization, as also a form determinate and invariable in its different parts, which compels each species to live in the places and in the climate where we find it, and has there preserved its known habits. "_My own conclusion_: Nature, in producing in succession every species of animal, and beginning with the least perfect or the simplest to end her work with the most perfect, has gradually complicated their structure; and these animals spreading generally throughout all the inhabitable regions of the globe, each species has received, through the influence of circumstances to which it has been exposed, the habits which we have observed, and the modifications in its organs which observation has shown us it possesses. "The first of these two conclusions is that believed up to the present day--namely, that held by nearly every one; it implies, in each animal, an unchanging organization and parts which have never varied, and which will never vary; it implies also that the circumstances of the places which each species of animal inhabits will never vary in these localities; for should they vary, the same animals could not live there, and the possibility of discovering similar forms elsewhere, and of transporting them there, would be forbidden. "The second conclusion is my own: it implies that, owing to the influence of circumstances on habits, and as the result of that of habits on the condition of the parts and even on that of the organization, each animal may receive in its parts and its organization, modifications susceptible of becoming very considerable, and of giving rise to the condition in which we find all animals. "To maintain that this second conclusion is unfounded, it is necessary at first to prove that each point of the surface of the globe never varies in its nature, its aspect, its situation whether elevated or depressed, its climate, etc., etc.; and likewise to prove that any part of animals does not undergo, even at the end of a long period, any modification by changes of circumstances, and by the necessity which directs them to another kind of life and action than that which is habitual to them. "Moreover, if a single fact shows that an animal for a long time under domestication differs from the wild form from which it has descended, and if in such a species in domesticity we find a great difference in conformation between the individuals submitted to such habits and those restricted to different habits, then it will be certain that the first conclusion does not conform to the laws of nature, and that, on the contrary, the second is perfectly in accord with them. "Everything combines then to prove my assertion--namely, that it is not the form, either of the body or of its parts, which gives rise to habits, and to the mode of life among animals; but that it is on the contrary the habits, the manner of living, and all the other influencing circumstances which have, after a time, constituted the form of the body and of the parts of animals. With the new forms, new faculties have been acquired, and gradually nature has come to form the animals as we actually see them. "Can there be in natural history a consideration more important, and to which we should give more attention, than that which I have just stated? "We will end this first part with the principles and the exposition of the natural classification of animals." In the fourth chapter of the third part (vol. ii. pp. 276-301) Lamarck treats of the internal feelings of certain animals, which provoke wants (_besoins_). This is the subject which has elicited so much adverse criticism and ridicule, and has in many cases led to the wholesale rejection of all of Lamarck's views. It is generally assumed or stated by Lamarck's critics, who evidently did not read his book carefully, that while he claimed that the plants were evolved by the direct action of the physical factors, that in the case of all the animals the process was indirect. But this is not correct. He evidently, as we shall see, places the lowest animals, those without (or what he supposed to be without) a nervous system, in the same category as the plants. He distinctly states at the outset that only certain animals and man are endowed with this singular faculty, "which consists in being able to experience _internal emotions_ which provoke the wants and different external or internal causes, and which give birth to the power which enables them to perform different actions." "The nervous fluid," he says, "can, then, undergo movements in certain parts of its mass, as well as in every part at once; moreover, it is these latter movements which constitute the _general movements_ (_ébranlements_) of this fluid, and which we now proceed to consider. "The general movements of the nervous fluid are of two kinds; namely, "1. Partial movements (_ébranlements_), which finally become general and end in a reaction. It is the movements of this sort which produce feeling. We have treated of them in the third chapter. "2. The movements which are general from the time they begin, and which form no reaction. It is these which constitute internal emotions, and it is of them alone of which we shall treat. "But previously, it is necessary to say a word regarding the _feeling of existence_, because this feeling is the source from which the inner emotions originate. "_On the Feeling of Existence._ "The feeling of existence (_sentiment d'existence_), which I shall call _inner feeling_,[183] so as to separate from it the idea of a general condition (_généralité_) which it does not possess, since it is not common to all living beings and not even to all animals, is a very obscure feeling, with which are endowed those animals provided with a nervous system sufficiently developed to give them the faculty of feeling. "This sentiment, very obscure as it is, is nevertheless very powerful, for it is the source of inner emotions which test (_éprouvent_) the individuals possessing it, and, as the result, this singular force urges these individuals to themselves produce the movements and the actions which their wants require. Moreover this feeling, considered as a very active _motor_, only acts thus by sending to the muscles which necessarily cause these movements and actions the nervous fluid which excites them.... "Indeed, as the result of organic or vital movements which are produced in every animal, that which possesses a nervous system sufficiently developed has physical sensibility and continually receives in every inner and sensitive part impressions which continually affect it, and which it feels in general without being able to distinguish any single one. "The sentiment of existence [consciousness] is general, since almost every sensitive part of the body shares in it. 'It constitutes this _me_ (_moi_) with which all animals, which are only sensitive, are penetrated, without perceiving it, but which those possessing a brain are able to notice, having the power of thought and of giving attention to it. Finally, it is in all the source of a power which is aroused by wants, which acts effectively only by emotion, and through which the movements and actions derive the force which produces them'.... "Finally, the inner feeling only manifests its power, and causes movements, when there exists a system for muscular movement, which is always dependent on the nervous system, and cannot take place without it." The author then states that these emotions of the organic sense may operate in the animals and in man either without or with an act of their will. "From what has been said, we cannot doubt but that the inner and general feeling which urges the animals possessing a nervous system fitted for feeling should be susceptible of being aroused by the causes which affect it; moreover, these causes are always the need both of satisfying hunger, of escaping dangers, of avoiding pain, of seeking pleasure, or that which is agreeable to the individual, etc. "The emotions of the inner feeling can only be recognized by man, who alone pays attention to them, but he only perceives those which are strong, which excite his whole being, such as a view from a precipice, a tragic scene, etc." Lamarck then divides the emotions into physical and moral, the latter arising from our ideas, thoughts--in short, our intellectual acts--in the account of which we need not follow him. In the succeeding chapter (V.) the author dilates on the force which causes actions in animals. "We know," he says "that plants can satisfy their needs without moving, since they find their food in the environing _milieux_. But it is not the same with animals, which are obliged to move about to procure their sustenance. Moreover, most of them have other wants to satisfy, which require other kinds of movements and acts." This matter is discussed in the author's often leisurely and prolix way, with more or less repetition, which we will condense. The lowest animals--those destitute of a nervous system--move in response to a stimulus from without. Nature has gradually created the different organs of animals, varying the structure and situation of these organs according to circumstances, and has progressively improved their powers. She has begun by borrowing from without, so to speak--from the environment--the _productive force_, both of organic movements and those of the external parts. "She has thus transported this force [the result of heat, electricity, and perhaps others (p. 307)] into the animal itself, and, finally, in the most perfect animals she has placed a great part of this force at their disposal, as I will soon show." This force incessantly introduced into the lowest animals sets in motion the visible fluids of the body and excites the irritability of their contained parts, giving rise to different contractile movements which we observe; hence the appearance of an irresistible propensity (_penchant_) which constrains them to execute those movements which by their continuity or their repetition give rise to habits. The most imperfect animals, such as the _Infusoria_, especially the monads, are nourished by absorption and by "an internal inhibition of absorbed matters." "They have," he says, "no power of seeking their food, they have not even the power of recognizing it, but they absorb it because it comes in contact with every side of them (_avec tous les points de leur individu_), and because the water in which they live furnishes it to them in sufficient abundance." "These frail animals, in which the subtile fluids of the environing _milieux_ constitute the stimulating cause of the orgasm, of irritability and of organic movements, execute, as I have said, contractile movements which, provoked and varied without ceasing by this stimulating cause, facilitate and hasten the absorptions of which I have just spoken." ... _On the Transportation of the force-producing Movements in the Interior of Animals._ "If nature were confined to the employment of its first means--namely, of a force entirely external and foreign to the animal--its work would have remained very important; the animals would have remained machines totally passive, and she would never have given origin in any of these living beings to the admirable phenomena of sensibility, of inmost feelings of existence which result therefrom, of the power of action, finally, of ideas, by which she can create the most wonderful of all, that of thought--in a word, intelligence. "But, wishing to attain these grand results, she has by slow degrees prepared the means, in gradually giving consistence to the internal parts of animals; in differentiating the organs, and in multiplying and farther forming the fluids contained, etc., after which she has transported into the interior of these animals that force productive of movements and of actions which in truth it would not dominate at first, but which she has come to place, in great part, at their disposition when their organization should become very much more perfect. "Indeed, from the time that the animal organization had sufficiently advanced in its structure to possess a nervous system--even slightly developed, as in insects--the animals provided with this organization were endowed with an intimate sense of their existence, and from that time the force productive of movements was conveyed into the very interior of the animal. "I have already made it evident that this internal force which produces movements and actions should derive its origin in the intimate feeling of existence which animals with a nervous system possess, and that this feeling, solicited or aroused by needs, should then start into motion the subtile fluid contained in the nerves and carry it to the muscles which should act, this producing the actions which the needs require. "Moreover, every want felt produces an emotion in the inner feeling of the individual which experiences it; and from this emotion of the feeling in question arises the force which gives origin to the movement of the parts which are placed in activity.... "Thus, in the animals which possess the power of acting--namely, the force productive of movements and actions--the inner feeling, which on each occasion originates this force, being excited by some need, places in action the power or force in question; excites the movement of displacement in the subtile fluid of the nerves--which the ancients called _animal spirits_; directs this fluid towards that of its organs which any want impels to action; finally makes this same fluid flow back into its habitual reservoirs when the needs no longer require the organ to act. "The inner feeling takes the place of the _will_; for it is now important to consider that every animal which does not possess the special organ in which or by which it executes thoughts, judgments, etc., has in reality no will, does not make a choice, and consequently cannot control the movements which its inner feeling excites. _Instinct_ directs these actions, and we shall see that this direction always results from emotions of the inner feeling, in which intelligence has no part, and from the organization even which the habits have modified, in such a manner that the needs of animals which are in this category, being necessarily limited and always the same in the same species, the inner feeling and, consequently, the power of acting, always produces the same actions. "It is not the same in animals which besides a nervous system have a brain [the author meaning the higher vertebrates], and which make comparisons, judgments, thoughts, etc. These same animals control more or less their power of action according to the degree of perfection of their brain; and although they are still strongly subjected to the results of their habits, which have modified their structure, they enjoy more or less freedom of the will, can choose, and can vary their acts, or at least some of them." Lamarck then treats of the consumption and exhaustion of the nervous fluid in the production of animal movements, resulting in fatigue. He next occupies himself with the origin of the inclination to the same actions, and of instinct in animals. "The cause of the well-known phenomenon which constrains almost all animals to always perform the same acts, and that which gives rise in man to a propensity (_penchant_) to repeat every action, becoming habitual, assuredly merits investigation. "The animals which are only 'sensible'[184]--namely, which possess no brain, cannot think, reason, or perform intelligent acts, and their perceptions being often very confused--do not reason and can scarcely vary their actions. They are, then, invariably bound by habits. Thus the insects, which of all animals endowed with feeling have the least perfect nervous system,[185] have perceptions of objects which affect them, and seem to have memory of them when they are repeated. Yet they can vary their actions and change their habits, though they do not possess the organ whose acts could give them the means. "_On the Instincts of Animals._ "We define instinct as the sum (_ensemble_) of the decisions (_déterminations_) of animals in their actions; and, indeed, some have thought that these determinations were the product of a rational choice, and consequently the fruit of experience. Others, says Cabanis, may think with the observers of all ages that several of these decisions should not be ascribed to any kind of reasoning, and that, without ceasing as for that to have their source in physical sensibility, they are most often formed without the will of the individuals able to have any other part than in better directing the execution. It should be added, without the will having any part in it; for when it does not act, it does not, of course, direct the execution. "If it had been considered that all the animals which enjoy the power of sensation have their inner feeling susceptible of being aroused by their needs, and that the movements of their nervous fluids, which result from these emotions, are constantly directed by this inner sentiment and by habits, then it has been felt that in all the animals deprived of intelligence all the decisions of action can never be the result of a rational choice, of judgment, of profitable experience--in a word, of will--but that they are subjected to needs which certain sensations excite, and which awaken the inclinations which urge them on. "In the animals even which enjoy the power of performing certain intelligent acts, it is still more often the inner feeling and the inclinations originating from habits which decide, without choice, the acts which animals perform. "Moreover, although the executing power of movements and of actions, as also the cause which directs them, should be entirely internal, it is not well, as has been done,[186] to limit to internal impressions the primary cause or provocation of these acts, with the intention to restrict to external impressions that which provokes intelligent acts; for, from what few facts are known bearing on these considerations, we are convinced that, either way, the causes which arouse and provoke acts are sometimes internal and sometimes external, that these same causes give rise in reality to impressions all of which act internally. "According to the idea generally attached to the word _instinct_ the faculty which this word expresses is considered as a light which illuminates and guides animals in their actions, and which is with them what reason is to us. No one has shown that instinct can be a force which calls into action; that this force acts effectively without any participation of the will, and that it is constantly directed by acquired inclinations." There are, the author states, two kinds of causes which can arouse the inner feeling (organic sense)--namely, those which depend on intellectual acts, and those which, without arising from it, immediately excite it and force it to direct its power of acting in the direction of acquired inclinations. "These are the only causes of this last kind, which constitute all the acts of _instinct_; and as these acts are not the result of deliberation, of choice, of judgment, the actions which arise from them always satisfy, surely and without error, the wants felt and the propensities arising from habits. "Hence, _instinct_ in animals is an inclination which necessitates that from sensations provoked while giving rise to wants the animal is impelled to act without the participation of any thought or any act of the will. "This propensity owes to the organization what the habits have modified in its favor, and it is excited by impressions and wants which arouse the organic sense of the individual and put it in the way of sending the nervous fluid in the direction which the propensity in activity needs to the muscles to be placed in action. "I have already said that the habit of exercising such an organ, or such a part of the body, to satisfy the needs which often spring up, should give to the subtile fluid which changes its place where is to be operated the power which causes action so great a facility in moving towards this organ, where it has been so often employed, that this habit should in a way become inherent in the nature of the individual, which is unable to change it. "Moreover, the wants of animals possessing a nervous system being, in each case, dependent on the Structure of these organisms, are: "1. Of obtaining any kind of food; "2. Of yielding to sexual fecundation which excites in them certain sensations; "3. Of avoiding pain; "4. Of seeking pleasure or happiness. "To satisfy these wants they contract different kinds of habits, which are transformed into so many propensities, which they can neither resist nor change. From this originate their habitual actions, and their special propensities to which we give the name of instinct.[187] "This propensity of animals to preserve their habits and to renew the actions resulting from them being once acquired, is then propagated by means of reproduction or generation, which preserves the organization and the disposition of parts in the state thus attained, so that this same propensity already exists in the new individuals even before they have exercised it. "It is thus that the same habits and the same _instinct_ are perpetuated from generation to generation in the different species or races of animals, without offering any notable variation,[188] so long as it does not suffer change in the circumstances essential to the mode of life." "_On the Industry of Certain Animals._ "In those animals which have no brain that which we call _industry_ as applied to certain of their actions does not deserve such a name, for it is a mistake to attribute to them a faculty which they do not possess. "Propensities transmitted and received by heredity (_génération_); habits of performing complicated actions, and which result from these acquired propensities; finally, different difficulties gradually and habitually overcome by as many emotions of the organic sense (_sentiment intérieur_), constitute the sum of actions which are always the same in the individuals of the same race, to which we inconsiderately give the name of _industry_. "The instinct of animals being formed by the habit of satisfying the four kinds of wants mentioned above, and resulting from the propensities acquired for a long time which urge them on in a way determined for each species, there comes to pass, in the case of some, only a complication in the actions which can satisfy these four kinds of wants, or certain of them, and, indeed, only the different difficulties necessary to be overcome have gradually compelled the animal to extend and make contrivances, and have led it, without choice or any intellectual act, but only by the emotions of the organic sense, to perform such and such acts. "Hence the origin, in certain animals, of different complicated actions, which has been called _industry_, and which are so enthusiastically admired, because it has always been supposed, at least tacitly, that these actions were contrived and deliberately planned, which is plainly erroneous. They are evidently the fruit of a necessity which has expanded and directed the habits of the animals performing them, and which renders them such as we observe. "What I have just said is especially applicable to the invertebrate animals, in which there enters no act of intelligence. None of these can indeed freely vary its actions; none of them has the power of abandoning what we call its _industry_ to adopt any other kind. "There is, then, nothing wonderful in the supposed industry of the ant-lion (_Myrmeleon formica-leo_), which, having thrown up a hillock of movable sand, waits until its booty is thrown down to the bottom of its funnel by the showers of sand to become its victim; also there is none in the manoeuvre of the oyster, which, to satisfy all its wants, does nothing but open and close its shell. So long as their organization is not changed they will always, both of them, do what we see them do, and they will do it neither voluntarily nor rationally. "This is not the case with the vertebrate animals, and it is among them, especially in the birds and mammals, that we observe in their actions traces of a true _industry_; because in difficult cases their intelligence, in spite of their propensity to habits, can aid them in varying their actions. These acts, however, are not common, and are only slightly manifested in certain races which have exercised them more, as we have had frequent occasion to remark." Lamarck then (chapter vi.) examines into the nature of the _will_, which he says is really the principle underlying all the actions of animals. The will, he says, is one of the results of thought, the result of a reflux of a portion of the nervous fluid towards the parts which are to act. He compares the brain to a register on which are imprinted ideas of all kinds acquired by the individual, so that this individual provokes at will an effusion of the nervous fluid on this register, and directs it to any particular page. The remainder of the second volume (chapter vii.) is devoted to the understanding, its origin and that of ideas. The following additions relative to chapters vii. and viii. of the first part of this work are from vol. ii., pp. 451-466. In the last of June, 1809, the menagerie of the Museum of Natural History having received a Phoca (_Phoca vitulina_), Lamarck, as he says, had the opportunity of observing its movements and habits. After describing its habits in swimming and moving on land and observing its relation to the clawed mammals, he says his main object is to remark that the seals do not have the hind legs arranged in the same direction as the axis of their body, because these animals are constrained to habitually use them to form a caudal fin, closing and widening, by spreading their digits, the paddle (_palette_) which results from their union. "The morses, on the contrary, which are accustomed to feed on grass near the shore, never use their hind feet as a caudal fin; but their feet are united together with the tail, and cannot separate. Thus in animals of similar origin we see a new proof of the effect of habits on the form and structure of organs." He then turns to the flying mammals, such as the flying squirrel (_Sciurus volans_, _ærobates_, _petaurista_, _sagitta_, and _volucella_), and then explains the origin of their adaptation for flying leaps. "These animals, more modern than the seals, having the habit of extending their limbs while leaping to form a sort of _parachute_, can _only_ make a very prolonged leap when they glide down from a tree or spring only a short distance from one tree to another. Now, by frequent repetitions of such leaps, in the individuals of these races the skin of their sides is expanded on each side into a loose membrane, which connects the hind and fore legs, and which, enclosing a volume of air, prevents their sudden falling. These animals are, moreover, without membranes between the fingers and toes. "The Galeopithecus (_Lemur volans_), undoubtedly a more ancient form but with the same habits as the flying squirrel (_Pteromys Geoff._), has the skin of the _flancs_ more ample, still more developed, connecting not only the hinder with the fore legs, but in addition the fingers and the tail with the hind feet. Moreover, they leap much farther than the flying squirrels, and even make a sort of flight.[189] "Finally, the different bats are probably mammals still older than the Galeopithecus, in the habit of extending their membrane and even their fingers to encompass a greater volume of air, so as to sustain their bodies when they fly out into the air. "By these habits, for so long a period contracted and preserved, the bats have obtained not only lateral membranes, but also an extraordinary elongation of the fingers of their fore feet (with the exception of the thumb), between which are these very ample membranes uniting them; so that these membranes of the hands become continuous with those of the flanks, and with those which connect the tail with the two hind feet, forming in these animals great membranous wings with which they fly perfectly, as everybody knows. "Such is then the power of habits, which have a singular influence on the conformation of parts, and which give to the animals which have for a long time contracted certain of them, faculties not found in other animals. "As regards the amphibious animals of which I have often spoken, it gives me pleasure to communicate to my readers the following reflections which have arisen from an examination of all the objects which I have taken into consideration in my studies, and seen more and more to be confirmed. "I do not doubt but that the mammals have in reality originated from them, and that they are the veritable cradle (_berceau_) of the entire animal kingdom. "Indeed, we see that the least perfect animals (and they are the most numerous) live only in the water; hence it is probable, as I have said (vol. ii., p. 85), that it is only in the water or in very humid places that nature causes and still forms, under favorable conditions, direct or spontaneous generations which have produced the simplest animalcules and those from which have successively been derived all the other animals. "We know that the Infusoria, the polyps, and the Radiata only live in the water; that the worms even only live some in the water and others in very damp places. "Moreover, regarding the worms, which seem to form an initial branch of the animal scale, since it is evident that the Infusoria form another branch, we may suppose that among those of them which are wholly aquatic--namely, which do not live in the bodies of other animals, such as the Gordius and many others still unknown--there are doubtless a great many different aquatic forms; and that among these aquatic worms, those which afterwards habitually expose themselves to the air have probably produced amphibious insects, such as the mosquitoes, the ephemeras, etc., etc., which have successively given origin to all the insects which live solely in the air. But several races of these having changed their habits by the force of circumstances, and having formed habits of a life solitary, retired, or hidden, have given rise to the arachnides, almost all of which also live in the air. "Finally, those of the arachnides which have frequented the water, which have consequently become progressively habituated to live in it, and which finally cease to expose themselves to the air--this indicates the relations which, connecting the Scolopendræ to Julus, this to the Oniscus, and the last to Asellus, shrimps, etc., have caused the existence of all the Crustacea. "The other aquatic worms which are never exposed to the air, multiplying and diversifying their races with time, and gradually making progress in the complication of their structure, have caused the formation of the Annelida, Cirripedia, and molluscs, which together form an uninterrupted portion of the animal scale. "In spite of the considerable hiatus which we observe between the known molluscs and the fishes, the molluscs, whose origin I have just indicated, have, by the intermediation of those yet remaining unknown, given origin to the fishes, as it is evident that the latter have given rise to the reptiles. "In continuing to consult the probabilities on the origin of different animals, we cannot doubt but that the reptiles, by two distinct branches which circumstances have brought about, have given rise on one side to the formation of birds, and on the other to that of amphibious mammals, which have given in their turn origin to all the other mammals.[190] "Indeed, the fishes having caused the formation of Batrachia, and these of the Ophidian reptiles, both having only one auricle in the heart, nature has easily come to give a heart with a double auricle to other reptiles which constitute two special branches; finally, she has easily arrived at the end of forming, in the animals which had originated from each of these branches, a heart with two ventricles. "Thus, among the reptiles whose heart has a double auricle, on the one side, the Chelonians seem to have given origin to the birds; if, independently of several relations which we cannot disregard, I should place the head of a tortoise on the neck of certain birds, I should perceive almost no disparity in the general physiognomy of the factitious animal; and on the other side, the saurians, especially the 'planicaudes,' such as the crocodiles, seem to have given origin to the amphibious mammals. "If the branch of the Chelonians has given rise to birds, we can yet presume that the palmipede aquatic birds, especially the _brevipennes_, such as the penguins and the _manchots_, have given origin to the monotremes. "Finally, if the branch of saurians has given rise to the amphibious mammals, it will be most probable that this branch is the source whence all the mammals have taken their origin. "I therefore believe myself authorized to think that the terrestrial mammals originally descended from those aquatic mammals that we call Amphibia. Because the latter being divided into three branches by the diversity of the habits which, with the lapse of time, they have adopted, some have caused the formation of the Cetacea, others that of the ungulated mammals, and still others that of the unguiculate mammals. "For example, those of the Amphibia which have preserved the habit of frequenting the shores differ in the manner of taking their food. Some among them accustoming themselves to browse on herbage, such as the morses and lamatines, gradually gave origin to the ungulate mammals, such as the pachyderms, ruminants, etc.; the others, such as the Phocidæ, contracting the habit of feeding on fishes and marine animals, caused the existence of the unguiculate mammals, by means of races which, while becoming differentiated, became entirely terrestrial. "But those aquatic mammals which would form the habit of never leaving the water, and only rising to breathe at the surface, would probably give origin to the different known cetaceans. Moreover, the ancient and complete habitation of the Cetacea in the ocean has so modified their structure that it is now very difficult to recognize the source whence they have derived their origin. "Indeed, since the enormous length of time during which these animals have lived in the depths of the sea, never using their hind feet in seizing objects, their disused feet have wholly disappeared, as also their skeleton, and even the pelvis serving as their attachment. "The alteration which the cetaceans have undergone in their limbs, owing to the influence of the medium in which they live and the habits which they have there contracted, manifests itself also in their fore limbs, which, entirely enveloped by the skin, no longer show externally the fingers in which they end; so that they only offer on each side a fin which contains concealed within it the skeleton of a hand. "Assuredly, the cetaceans being mammals, it entered into the plan of their structure to have four limbs like the others, and consequently a pelvis to sustain their hind legs. But here, as elsewhere, that which is lacking in them is the result of atrophy brought about, at the end of a long time, by the want of use of the parts which were useless. "If we consider that in the Phocæ, where the pelvis still exists, this pelvis is impoverished, narrowed, and with no projections on the hips, we see that the lessened (_médiocre_) use of the hind feet of these animals must be the cause, and that if this use should entirely cease, the hind limbs and even the pelvis would in the end disappear. "The considerations which I have just presented may doubtless appear as simple conjectures, because it is possible to establish them only on direct and positive proofs. But if we pay any attention to the observations which I have stated in this work, and if then we examine carefully the animals which I have mentioned, as also the result of their habits and their surroundings, we shall find that these conjectures will acquire, after this examination, an eminent probability. "The following _tableau_[191] will facilitate the comprehension of what I have just stated. It will be seen that, in my opinion, the animal scale begins at least by two special branches, and that in the course of its extent some branchlets (_rameaux_) would seem to terminate in certain places. "This series of animals beginning with two branches where are situated the most imperfect, the first of these branches received their existence only by direct or spontaneous generation. "A strong reason prevents our knowing the changes successively brought about which have produced the condition in which we observe them; it is because we are never witnesses of these changes. Thus we see the work when done, but never watching them during the process, we are naturally led to believe that things have always been as we see them, and not as they have progressively been brought about. "Among the changes which nature everywhere incessantly produces in her _ensemble_, and her laws remain always the same, such of these changes as, to bring about, do not need much more time than the duration of human life, are easily understood by the man who observes them; but he cannot perceive those which are accomplished at the end of a considerable time. "If the duration of human life only extended to the length of a _second_, and if there existed one of our actual clocks mounted and in movement, each individual of our species who should look at the hour-hand of this clock would never see it change its place in the course of his life, although this hand would really not be stationary. The observations of thirty generations would never learn anything very evident as to the displacement of this hand, because its movement, only being that made during half a minute, would be too slight to make an impression; and if observations much more ancient should show that this same hand had really moved, those who should see the statement would not believe it, and would suppose there was some error, each one having always seen the hand on the same point of the dial-plate. "I leave to my readers all the applications to be made regarding this supposition. "_Nature_, that immense totality of different beings and bodies, in every part of which exists an eternal circle of movements and changes regulated by law; totality alone unchangeable, so long as it pleases its SUBLIME AUTHOR to make it exist, should be regarded as a whole constituted by its parts, for a purpose which its Author alone knows, and not exclusively for any one of them. "Each part necessarily is obliged to change, and to cease to be one in order to constitute another, with interests opposed to those of all; and if it has the power of reasoning it finds this whole imperfect. In reality, however, this whole is perfect, and completely fulfils the end for which it was designed." The last work in which Lamarck discussed the theory of descent was in his introduction to the _Animaux sans Vertèbres_. But here the only changes of importance are his four laws, which we translate, and a somewhat different phylogeny of the animal kingdom. The four laws differ from the two given in the _Philosophie zoologique_ in his theory (the second law) accounting for the origin of a new organ, the result of a new need. "_First law_: Life, by its proper forces, continually tends to increase the volume of every body which possesses it, and to increase the size of its parts, up to a limit which it brings about. "_Second law_: The production of a new organ in an animal body results from the supervention of a new want (_besoin_) which continues to make itself felt, and of a new movement which this want gives rise to and maintains. "_Third law_: The development of organs and their power of action are constantly in ratio to the employment of these organs. "_Fourth law_: Everything which has been acquired, impressed upon, or changed in the organization of individuals, during the course of their life is preserved by generation and transmitted to the new individuals which have descended from those which have undergone those changes." In explaining the second law he says: "The foundation of this law derives its proof from the third, in which the facts known allow of no doubt; for, if the forces of action of an organ, by their increase, further develop this organ--namely, increase its size and power, as is constantly proved by facts--we may be assured that the forces by which it acts, just originated by a new want felt, would necessarily give birth to the organ adapted to satisfy this new want, if this organ had not before existed. "In truth, in animals so low as not to be able to _feel_, it cannot be that we should attribute to a felt want the formation of a new organ, this formation being in such a case the product of a mechanical cause, as that of a new movement produced in a part of the fluids of the animal. "It is not the same in animals with a more complicated structure, and which are able to _feel_. They feel wants, and each want felt, exciting their inner feeling, forthwith sets the fluids in motion and forces them towards the point of the body where an action may satisfy the want experienced. Now, if there exists at this point an organ suitable for this action, it is immediately cited to act; and if the organ does not exist, and only the felt want be for instance pressing and continuous, gradually the organ originates, and is developed on account of the continuity and energy of its employment. "If I had not been convinced: 1, that the thought alone of an action which strongly interests it suffices to arouse the _inner feeling_ of an individual; 2, that a felt want can itself arouse the feeling in question; 3, that every emotion of _inner feeling_, resulting from a want which is aroused, directs at the same instant a mass of nervous fluid to the points to be set in activity, that it also creates a flow thither of the fluids of the body, and especially nutrient ones; that, finally, it then places in activity the organs already existing, or makes efforts for the formation of those which would not have existed there, and which a continual want would therefore render necessary--I should have had doubts as to the reality of the law which I have just indicated. "But, although it may be very difficult to verify this law by observation, I have no doubt as to the grounds on which I base it, the necessity of its existence being involved in that of the third law, which is now well established. "I conceive, for example, that a _gasteropod mollusc_, which, as it crawls along, finds the need of feeling the bodies in front of it, makes efforts to touch those bodies with some of the foremost parts of its head, and sends to these every time supplies of nervous fluids, as well as other fluids--I conceive, I say, that it must result from this reiterated afflux towards the points in question that the nerves which abut at these points will, by slow degrees, be extended. Now, as in the same circumstances other fluids of the animal flow also to the same places, and especially nourishing fluids, it must follow that two or more tentacles will appear and develop insensibly under those circumstances on the points referred to. "This is doubtless what has happened to all the races of _Gasteropods_, whose wants have compelled them to adopt the habit of feeling bodies with some part of their head. "But if there occur, among the _Gasteropods_, any races which, by the circumstances which concern their mode of existence or life, do not experience such wants, then their head remains without tentacles; it has even no projection, no traces of tentacles, and this is what has happened in the case of _Bullæa_, _Bulla_, and _Chiton_." In the _Supplément à la Distribution générale des Animaux_ (Introduction, p. 342), concerning the real order of origin of the invertebrate classes, Lamarck proposes a new genealogical tree. He states that the order of the animal series "is far from simple, that it is branching, and seems even to be composed of several distinct series;" though farther on (p. 456) he adds: "Je regarde _l'ordre de la production_ des animaux comme formé de deux séries distinctes. "Ainsi, je soumets à la méditation des zoologistes l'ordre présumé de la _formation_ des animaux, tel que l'exprime le tableau suivant:" In the matter of the origin of instinct, as in evolution in general, Lamarck appears to have laid the foundation on which Darwin's views, though he throws aside Lamarck's factors, must rest. The "inherited habit" theory is thus stated by Lamarck. Instinct, he claims, is not common to all animals, since the lowest forms, like plants, are entirely passive under the influences of the surrounding medium; they have no wants, are automata. "But animals with a nervous system have _wants_, _i.e._, they feel hunger, sexual desires, they desire to avoid pain or to seek pleasure, etc. To satisfy these wants they contract habits, which are gradually transformed into so many propensities which they can neither resist nor change. Hence arise habitual actions and special _propensities_, to which we give the name of _instinct_. "These propensities are inherited and become innate in the young, so that they act instinctively from the moment of birth. Thus the same habits and instincts are perpetuated from one generation to another, with no _notable_ variations, so long as the species does not suffer change in the circumstances essential to its mode of life." The same views are repeated in the introduction to the _Animaux sans Vertèbres_ (1815), and again in 1820, in his last work, and do not need to be translated, as they are repetitions of his previously published views in the _Philosophie zoologique_. Unfortunately, to illustrate his thoughts on instinct Lamarck does not give us any examples, nor did he apparently observe to any great extent the habits of animals. In these days one cannot follow him in drawing a line--as regards the possession of instincts--between the lowest organisms, or Protozoa, and the groups provided with a nervous system. _Lamarck's meaning of the word "besoins," or wants or needs._--Lamarck's use of the word wants or needs (_besoins_) has, we think, been greatly misunderstood and at times caricatured or pronounced as "absurd." The distinguished French naturalist, Quatrefages, although he was not himself an evolutionist, has protested against the way Lamarck's views have been caricatured. By nearly all authors he is represented as claiming that by simply "willing" or "desiring" the individual bird or other animal radically and with more or less rapidity changed its shape or that of some particular organ or part of the body. This is, as we have seen, by no means what he states. In no instance does he speak of an animal as simply "desiring" to modify an organ in any way. The doctrine of appetency attributed to Lamarck is without foundation. In all the examples given he intimates that owing to changes in environment, leading to isolation in a new area separating a large number of individuals from their accustomed habitat, they are driven by necessity (_besoin_) or new needs to adopt a new or different mode of life--new habits. These efforts, whatever they may be--such as attempts to fly, swim, wade, climb, burrow, etc., continued for a long time "in all the individuals of its species," or the great number forced by competition to migrate and become segregated from the others of the original species--finally, owing to the changed surroundings, affect the mass of individuals thus isolated, and their organs thus exercised in a special direction undergo a slow modification. Even so careful a writer as Dr. Alfred R. Wallace does not quite fairly, or with exactness, state what Lamarck says, when in his classical essay of 1858 he represents Lamarck as stating that the giraffe acquired its long neck by _desiring_ to reach the foliage of the more lofty shrubs, and constantly stretching its neck for the purpose. On the contrary, he does not use the word "desiring" at all. What Lamarck does say is that-- "The giraffe lives in dry, desert places, without herbage, so that it is obliged to browse on the leaves of trees, and is continually forced to reach up to them. It results from this habit, continued for a long time in all the individuals of its species, that its fore limbs have become so elongated that the giraffe, without raising itself erect on its hind legs, raises its head and reaches six meters high (almost twenty feet)."[192] We submit that this mode of evolution of the giraffe is quite as reasonable as the very hypothetical one advanced by Mr. Wallace;[193] _i.e._, that a variety occurred with a longer neck than usual, and these "at once secured a fresh range of pasture over the same ground as their shorter-necked companions, and on the first scarcity of food were thereby enabled to outlive them." Mr. Wallace's account also of Lamarck's general theory appears to us to be one-sided, inadequate, and misleading. He states it thus: "The hypothesis of Lamarck--that progressive changes in species have been produced by the attempts of animals to increase the development of their own organs, and thus modify their structure and habits." This is a caricature of what Lamarck really taught. Wants, needs (_besoins_), volitions, desires, are not mentioned by Lamarck in his two fundamental laws (see p. 303), and when the word _besoins_ is introduced it refers as much to the physiological needs as to the emotions of the animal resulting from some new environment which forces it to adopt new habits such as means of locomotion or of acquiring food. It will be evident to one who has read the original or the foregoing translations of Lamarck's writings that he does not refer so much to mental desires or volitions as to those physiological wants or needs thrust upon the animal by change of circumstances or by competition; and his _besoins_ may include lust, hunger, as well as the necessity of making muscular exertions such as walking, running, leaping, climbing, swimming, or flying. As we understand Lamarck, when he speaks of the incipient giraffe or long-necked bird as making efforts to reach up or outwards, the efforts may have been as much physiological, reflex, or instinctive as mental. A recent writer, Dr. R. T. Jackson, curiously and yet naturally enough uses the same phraseology as Lamarck when he says that the long siphon of the common clam (Mya) "was brought about by the effort to reach the surface, induced by the habit of deep burial" in its hole.[194] On the other hand, can we in the higher vertebrates entirely dissociate the emotional and mental activities from their physiological or instinctive acts? Mr. Darwin, in his _Expressions of the Emotions in Man and Animals_, discusses in an interesting and detailed way the effects of the feelings and passions on some of the higher animals. It is curious, also, that Dr. Erasmus Darwin went at least as far as Lamarck in claiming that the transformations of animals "are in part produced by their own exertions in consequence of their desires and aversions, of their pleasures and their pains, or of irritations or of associations." Cope, in the final chapter of his _Primary Factors of Organic Evolution_, entitled "The Functions of Consciousness," goes to much farther extremes than the French philosopher has been accused of doing, and unhesitatingly attributes consciousness to all animals. "Whatever be its nature," he says, "the preliminary to any animal movement which is not automatic is an effort." Hence he regards effort as the immediate source of all movement, and considers that the control of muscular movements by consciousness is distinctly observable; in fact, he even goes to the length of affirming that reflex acts are the product of conscious acts, whereas it is plain enough that reflex acts are always the result of some stimulus. Another case mentioned by Lamarck in his _Animaux sans Vertèbres_, which has been pronounced as absurd and ridiculous, and has aided in throwing his whole theory into disfavor, is his way of accounting for the development of the tentacles of the snail, which is quoted on p. 348. This account is a very probable and, in fact, the only rational explanation. The initial cause of such structures is the intermittent stimulus of occasional contact with surrounding objects, the irritation thus set up causing a flow of the blood to the exposed parts receiving the stimuli. The general cause is the same as that concerned in the production of horns and other hard defensive projections on the heads of various animals. In commenting on this case of the snail, Professor Cleland, in his just and discriminating article on Lamarck, says: "However absurd this may seem, it must be admitted that, unlimited time having been once granted for organs to be developed in series of generations, the objections to their being formed in the way here imagined are only such as equally apply to the theory of their origin by natural selection.... In judging the reasonableness of the second law of Lamarck [referring to new wants, see p. 346] as compared with more modern and now widely received theories, it must be observed that it is only an extension of his third law; and that third law is a fact. The strengthening of the blacksmith's arm by use is proverbially notorious. It is, therefore, only the sufficiency of the Lamarckian hypothesis to explain the first commencement of new organs which is in question, if evolution by the mere operation of forces acting in the organic world be granted; and surely the Darwinian theory is equally helpless to account for the beginning of a new organ, while it demands as imperatively that every stage in the assumed hereditary development of an organ must have been useful.... Lamarck gave great importance to the influence of new wants acting indirectly by stimulating growth and use. Darwin has given like importance to the effects of accidental variations acting indirectly by giving advantage in the struggle for existence. The speculative writings of Darwin have, however, been interwoven with a vast number of beautiful experiments and observations bearing on his speculations, though by no means proving his theory of evolution; while the speculations of Lamarck lie apart from his wonderful descriptive labors, unrelieved by intermixture with other matters capable of attracting the numerous class who, provided they have new facts set before them, are not careful to limit themselves to the conclusions strictly deducible therefrom. But those who read the _Philosophie Zoologique_ will find how many truths often supposed to be far more modern are stated with abundant clearness in its pages." (_Encyc. Brit._, art. "Lamarck.") COMPARATIVE SUMMARY OF THE VIEWS OF THE FOUNDERS OF THE THEORY OF EVOLUTION, WITH DATES OF PUBLICATION. -------------+-------------+------------------------+------------+------------ |Erasmus | |Geoffroy St.|Charles Buffon |Darwin |Lamarck |Hilaire |Darwin (1761-1778). |(1790-1794). |(1801-1809-1815). |(1795-1831).|(1859). -------------+-------------+------------------------+------------+------------ | | | | All animals |All animals |All organisms arose from|Unity of |Universal possibly |derived from |germs. First germ |organization|tendency to derived from |a single |originated by |in animal |fortuitous a single |filament. |spontaneous generation. |kingdom. |variability type. | |Development from the | |assumed. | |simple to the complex. |Change of | Time, its | |Animal series not |"milieu | great length,| |continuous, but |ambiant," | stated. | |tree-like; graduated |direct. | | |from monad to man; | | Immutability | |constructed the first | | of species | |phylogenetic tree. | | stated and | | |Founded the |Struggle then denied. |Time, great |Time, great length of, |doctrine of |for |length of, |definitely postulated; |homologies. |existence. Nature |definitely |its duration practically| | advances by |demanded. |unlimited. | | gradations, | | | | passing from | |Uniformitarianism of | | one species | |Hutton and of Lyell |Founder of | to another by| |anticipated. |teratology. | imperceptible| | | | degrees. |Effects of |Effects of favorable |His embryo- | |change of |circumstances, such as |logical | Changes in |climate, |changes of environment, |studies | distribution |direct |climate, soil, food, |influenced | of land and |(briefly |temperature; direct in |his | water as |stated). |case of plants and |philosophic | causing | |lowest animals, indirect|views. | variation. | |in case of the higher | | | |animals and man. | | Effects of | | | | changes of | |Conditions of existence | | climate, | |remaining constant, | | direct. | |species do not vary and | |Competition | |vice-versa. | |strongly Effects of | | | |advocated. changes of | |Struggle for existence; | | food. | |stronger devour the | |Natural |Domesti- |weaker. Competition | |selection. Effects of |cation |stated in case of ai or |Species are | domesti- |briefly |sloth. Balance of |"different |Sexual cation. |referred to. |nature. |modifi- |selection. | | |cations of | Effects of |Effects of |Effects of use and |one and the |Effects of use. (The |use: |disuse, discussed at |same type." |use and only examples|characters |length. | |disuse (in given are the|produced by | | |some callosities |their own |Vestigial structures the| |cases). on legs of |exertions in |remains of organs | | camel, of |consequence |actively used by | | baboon, and |of their |ancestors of present | | the |desires, |forms. | | thickening by|aversions, | | | use of soles |lust, hunger,|New wants or necessities| | on man's |and security.|induced by changes of | | feet.) | |climate, habitat, etc., | | |Sexual |result in production of | | |selection, |new propensities, new | | |law of |habits, and functions. | | |battle. | | | | |Change of habits | | |Protective |originate organs; change| | |mimicry. |of functions create new | | | |organs; formation of new| | |Origin of |habits precede the | | |organs before|origin of new or | | |development |modification of organs | | |of their |already formed. | | |functions. | | | | |Geographical isolation | |Isolation |Inheritance |suggested as a factor in| |"an |of acquired |case of man. | |important |characters | | |element." |(vaguely |Swamping effects of | | |stated). |crossing. | | | | | | |Instincts |Lamarck's definition of | | |result of |species the most | | |imitation. |satisfactory yet stated.| | | | | | |Opposed |Inheritance of acquired | |Inheritance |preformation |characters. | |of acquired |views of | | |characters. |Haller and |Instinct the result of | | |Bonnet. |inherited habits. | | | | | | | |Opposed preformation | | | |views; epigenesis | | | |definitely stated and | | | |adopted. | | | | | | -------------+-------------+------------------------+------------+------------ FOOTNOTES: [179] [Cabanis.] _Rapp. du Phys. et du Moral de l'Homme_, pp. 38 à 39, et 85. [180] Lamarck's idea of the animal series was that of a branched one, as shown by his genealogical tree on p. 193, and he explains that the series begins at least by two special branches, these ending in branchlets. He thus breaks entirely away from the old idea of a continuous ascending series of his predecessors Bonnet and others. Professor R. Hertwig therefore makes a decided mistake and does Lamarck a great injustice in his "Zoölogy," where he states: "Lamarck, in agreement with the then prevailing conceptions, regarded the animal kingdom as a series grading from the lowest primitive animal up to man" (p. 26); and again, on the next page, he speaks of "the theory of Geoffroy St.-Hilaire and Lamarck" as having in it "as a fundamental error the doctrine of the serial arrangement of the animal world" (English Trans.). Hertwig is in error, and could never have carefully read what Lamarck did say, or have known that he was the first to throw aside the serial arrangement, and to sketch out a genealogical tree. [181] The foregoing pages (283-286) are reprinted by the author from the _Discours_ of 1803. See pp. 266-270. [182] Perrier thus comments on this passage: "_Ici nous sommes bien près, semble-t-il, non seulement de la lutte pour la vie telle one la concevra Darwin, mais même de la sélection naturelle. Malheureusement, au lieu de poursuivre l'idée, Lamarck aussitôt s'engage dans une autre voie_," etc. (_La Philosophie zoologique avant Darwin_, p. 81). [183] The expression "_sentiment intérieur_" may be nearly equivalent to the "organic sense" of modern psychologists, but more probably corresponds to our word consciousness. [184] Lamarck's division of _Animaux sensibles_ comprises the insects, arachnids, crustacea, annelids, cirrhipedes, and molluscs. [185] Rather a strange view to take, as the brain of insects is now known to be nearly as complex as that of mammals. [186] Richerand, _Physiologie_. vol ii. p. 151. [187] "As all animals do not have the power of performing voluntary acts, so in like manner _instinct_ is not common to all animals: for those lacking the nervous system also want the organic sense, and can perform no instinctive acts. "These imperfect animals are entirely passive, they do nothing of themselves, they have no wants, and nature as regards them treats them as she does plants. But as they are irritable in their parts, the means which nature employs to maintain their existence enables them to execute movements which we call actions." It thus appears that Lamarck practically regards the lowest animals as automata, but we must remember that the line he draws between animals with and without a nervous system is an artificial one, as some of the forms which he supposed to be destitute of a nervous system are now known to possess one. [188] It should be noticed that Lamarck does not absolutely state that there are no variations whatever in instinct. His words are much less positive: "_Sans offrer de variation notable._" This dues not exclude the fact, discovered since his time, that instincts are more or less variable, thus affording grounds for Darwin's theory of the origin of new kinds of instincts from the "accidental variation of instincts." Professor James' otherwise excellent version of Lamarck's view is inexact and misleading when he makes Lamarck say that instincts are "perpetuated _without variation_ from one generation to another, so long as the outward conditions of existence remain the same" (_The Principles of Psychology_, vol. ii., p. 678, 1890). He leaves out the word notable. The italics are ours. Farther on (p. 337), it will be seen that Lamarck acknowledges that in birds and mammals instinct is variable. [189] It is interesting to compare with this Darwin's theory of the origin of the same animals, the flying squirrels and Galeopithecus (_Origin of Species_, 5th edition, New York, pp. 173-174), and see how he invokes the Lamarckian factors of change of "climate and vegetation" and "changing conditions of life," to originate the variations before natural selection can act. His account is a mixture of Lamarckism with the added Darwinian factors of competition and natural selection. We agree with this view, that the change in environment and competition sets the ball in motion, the work being finished by the selective process. The act of springing and the first attempts at flying also involve strong emotions and mental efforts, and it can hardly be denied that these Lamarckian factors came into continual play during the process of evolution of these flying creatures. [190] This sagacious, though crude suggestion of the origin of birds and mammals from the reptiles is now, after the lapse of nearly a century, being confirmed by modern morphologists and palæontologists. [191] Reproduced on page 193. [192] This is taken from my article, "Lamarck and Neo-lamarckianism," in the _Open Court_, Chicago, February, 1897. Compare also "Darwin Wrong," etc., by R. F. Licorish, M.D., Barbadoes, 1898, reprinted in _Natural Science_, April, 1899. [193] _Natural Selection_, pp. 41-42. [194] _American Naturalist_, 1891, p. 17. CHAPTER XVIII LAMARCK'S THEORY AS TO THE EVOLUTION OF MAN Lamarck's views on the origin of man are contained in his _Recherches sur l'Organisation des Corps vivans_ (1802) and his _Philosophie zoologique_, published in 1809. We give the following literal translation in full of the views he presented in 1802, and which were probably first advanced in lectures to his classes. "As to man, his origin, his peculiar nature, I have already stated in this book that I have not kept these subjects in view in making these observations. His extreme superiority over the other living creatures indicates that he is a privileged being who has in common with the animals only that which concerns animal life. "In truth, we observe a sort of gradation in the intelligence of animals, like what exists in the gradual improvement of their organization, and we remark that they have ideas, memory; that they think, choose, love, hate, that they are susceptible of jealousy, and that by different inflexions of their voice and by signs they communicate with and understand each other. It is not less evident that man alone is endowed with reason, and that on this account he is clearly distinguished from all the other productions of nature. "However, were it not for the picture that so many celebrated men have drawn of the weakness and lack of human reason; were it not that, independently of all the freaks into which the passions of man almost constantly allure him, the _ignorance_ which makes him the opinionated slave of custom and the continual dupe of those who wish to deceive him; were it not that his reason has led him into the most revolting errors, since we actually see him so debase himself as to worship animals, even the meanest, of addressing to them his prayers, and of imploring their aid; were it not, I say, for these considerations, should we feel authorized to raise any doubts as to the excellence of this special light which is the attribute of man? "An observation which has for a long time struck me is that, having remarked that the habitual use and exercise of an organ proportionally develops its size and functions, as the lack of employment weakens in the same proportion its power, and even more or less completely atrophies it, I am apprised that of all the organs of man's body which is the most strongly submitted to this influence, that is to say, in which the effects of exercise and of habitual use are the most considerable, is it not the organ of thought--in a word, is it not the brain of man? "Compare the extraordinary difference existing in the degree of intelligence of a man who rarely exercises his powers of thought, who has always been accustomed to see but a small number of things, only those related to his ordinary wants and to his limited desires; who at no time thinks about these same objects, because he is obliged to occupy himself incessantly with providing for these same wants; finally, who has few ideas, because his attention, continually fixed on the same things, makes him notice nothing, that he makes no comparisons, that he is in the very heart of nature without knowing it, that he looks upon it almost in the same way as do the beasts, and that all that surrounds him is nothing to him: compare, I say, the intelligence of this individual with that of the man who, prepared at the outset by education, has contracted the useful practice of exercising the organ of his thought in devoting himself to the study of the principal branches of knowledge; who observes and compares everything he sees and which affects him; who forgets himself in examining everything he can see, who insensibly accustoms himself to judge of everything for himself, instead of giving a blind assent to the authority of others; finally, who, stimulated by reverses and especially by injustice, quietly rises by reflection to the causes which have produced all that we observe both in nature and in human society; then you will appreciate how enormous is the difference between the intelligence of the two men in question. "If Newton, Bacon, Montesquieu, Voltaire, and so many other men have done honor to the human species by the extent of their intelligence and their genius, how nearly does the mass of brutish, ignorant men approach the animal, becoming a prey to the most absurd prejudices and constantly enslaved by their habits, this mass forming the majority of all nations? "Search deeply the facts in the comparison I have just made, you will see how in one part the organ which serves for acts of thought is perfected and acquires greater size and power, owing to sustained and varied exercise, especially if this exercise offers no more interruptions than are necessary to prevent the exhaustion of its powers; and, on the other hand, you will perceive how the circumstances which prevent an individual from exercising this organ, or from exercising it habitually only while considering a small number of objects which are always of the same nature, impede the development of his intellectual faculties. "After what I have just stated as to the results in man of a slight exercise of the organ by which he thinks, we shall no longer be astonished to see that in the nations which have come to be the most distinguished, because there is among them a small number of men who have been able, by observation and reflection, to create or advance the higher sciences, the multitude in these same nations have not been for all that exempted from the most absurd errors, and have not the less always been the dupe of impostors and victims of their prejudices. "Such is, in fact, the fatality attached to the destiny of man that, with the exception of a small number of individuals who live under favorable though special circumstances, the multitude, forced to continually busy itself with providing for its needs, remains permanently deprived of the knowledge which it should acquire; in general, exercises to a very slight extent the organ of its intelligence; preserves and propagates a multitude of prejudices which enslave it, and cannot be as happy as those who, guiding it, are themselves guided by reason and justice. "As to the animals, besides the fact that they in descending order have the brain less developed, they are otherwise proportionally more limited in the means of exercising and of varying their intellectual processes. They each exercise them only on a single or on some special points, on which they become more or less expert according to their species. And while their degree of organization remains the same and the nature of their needs (_besoins_) does not vary, they can never extend the scope of their intelligence, nor apply it to other objects than to those which are related to their ordinary needs. "Some among them, whose structure is a little more perfect than in others, have also greater means of varying and extending their intellectual faculties; but it is always within limits circumscribed by their necessities and habits. "The power of habit which is found to be still so great in man, especially in one who has but slightly exercised the organ of his thought, is among animals almost insurmountable while their physical state remains the same. Nothing compels them to vary their powers, because they suffice for their wants and these require no change. Hence it is constantly the same objects which exercise their degree of intelligence, and it results that these actions are always the same in each species. "The sole acts of variation, _i.e._, the only acts which rise above the limits of habits, and which we see performed in animals whose organization allows them to, are _acts of imitation_. I only speak of actions which they perform voluntarily or freely (_actions qu'ils font de leur plein gré_). "Birds, very limited in this respect in the powers which their structure furnishes, can only perform acts of imitation with their vocal organ; this organ, by their habitual efforts to render the sounds, and to vary them, becomes in them very perfect. Thus we know that several birds (the parrot, starling, raven, jay, magpie, canary bird, etc.) imitate the sounds they hear. "The monkeys, which are, next to man, the animals by their structure having the best means to this end, are most excellent imitators, and there is no limit to the things they can mimic. "In man, infants which are still of the age when simple ideas are formed on various subjects, and who think but little, forming no complex ideas, are also very good imitators of everything which they see or hear. "But if each order of things in animals is dependent on the state of organization occurring in each of them, which is not doubted, there is no occasion for thinking that in these same animals the order which is superior to all the others in organization is proportionally so also in extent of means, invariability of actions, and consequently in intellectual powers. "For example, in the mammals which are the most highly organized, the _Quadrumana_, which form a part of them, have, besides the advantages over other mammals, a conformation in several of their organs which considerably increases their powers, which allows of a great variability in their actions, and which extends and even makes predominant their intelligence, enabling them to deal with a greater variety of objects with which to exercise their brain. It will doubtless be said: But although man may be a true mammal in his general structure, and although among the mammals the _Quadrumana_ are most nearly allied to him, this will not be denied, not only that man is strongly distinguished from the _Quadrumana_ by a great superiority of intelligence, but he is also very considerably so in several structural features which characterize him. "First, the occipital foramen being situated entirely at the base of the cranium of man and not carried up behind, as in the other vertebrates, causes his head to be posed at the extremity of the vertebral column as on a pivot, not bowed down forward, his face not looking towards the ground. This position of the head of man, who can easily turn it to different sides, enables him to see better a larger number of objects at one time, than the much inclined position of the head of other mammals allows them to see. "Secondly, the remarkable mobility of the fingers of the hand of man, which he employs either all together or several together, or each separately, according to his pleasure, and besides, the sense of touch highly developed at the extremity of these same fingers, enables him to judge the nature of the bodies which surround him, to recognize them, to make use of them--means which no other animals possess to such a degree. "Thirdly, by the state of his organization man is able to hold himself up and walk erect. He has, for this attitude which is natural to him, large muscles at the lower extremities which are adapted to this end, and it would thus be as difficult to walk habitually on his four extremities as it would be for the other mammals, and even for the _Quadrumana_, to walk so habitually erect on the soles of their feet. "Moreover, man is not truly quadrumanous; for he has not, like the monkeys, an almost equal facility in using the fingers of his feet, and of seizing objects with them. In the feet of man the thumbs are not in opposition to the other fingers to use in grasping, as in monkeys, etc. "I appreciate all these reasons, and I see that man, although near the _Quadrumana_, is so distinct that he alone represents a separate order, belonging to a single genus and species, offering, however, many different varieties. This order may be, if it is desired, that of the _Bimana_. "However, if we consider that all the characteristics which have been cited are only differences in degree of structure, may we not suppose that this special condition of organization of man _has been gradually acquired at the close of a long period of time, with the aid of circumstances which have proved favorable?_[195] What a subject for reflection for those who have the courage to enter into it! "If the _Quadrumana_ have not the occipital opening situated directly at the base of the cranium as in man, it is assuredly much less raised posteriorly than in the dog, cat, and all the other mammals. Thus they all may quite often stand erect, although this attitude for them is very irksome. "I have not observed the situation of the occipital opening of the jacko or orang-outang (_Simia satyrus_ L.); but as I know that this animal almost habitually walks erect, though it has no strength in its legs, I suppose that the occipital foramen is not situated so far from the base of the skull as in the other _Quadrumana_. "The head of the negro, less flattened in front than that of the European man, necessarily has the occipital foramen central. "The more should the jacko contract the habit of walking about, the less mobility would he have in his toes, so that the thumbs of the feet, which are already much shorter than the other digits, would gradually cease to be placed in opposition to the other toes, and to be useful in grasping. The muscles of its lower extremities would acquire proportionally greater thickness and strength. Then the increased or more frequent exercise of the fingers of its hands would develop nervous masses at their extremities, thus rendering the sense of touch more delicate. This is what our train of reasoning indicates from the consideration of a multitude of facts and observations which support it."[196] The subject is closed by a quotation from Grandpré on the habits of the chimpanzee. It is not of sufficient importance to be here reproduced. Seven years after the publication of these views, Lamarck again returns to the subject in his _Philosophie zoologique_, which we translate. "_Some Observations Relative to Man_. "If man were distinguished from the animals by his structure alone, it would be easy to show that the structural characters which place him, with his varieties, in a family by himself, are all the product of former changes in his actions, and in the habits which he has adopted and which have become special to the individuals of his species. "Indeed, if any race whatever of _Quadrumana_, especially the most perfect, should lose, by the necessity of circumstances or from any other cause, the habit of climbing trees, and of seizing the branches with the feet, as with the hands, to cling to them; and if the individuals of this race, during a series of generations, should be obliged to use their feet only in walking, and should cease to use their hands as feet, there is no doubt, from the observations made in the preceding chapter, that these _Quadrumana_ would be finally transformed into _Bimana_, and that the thumbs of their feet would cease to be shorter than the fingers, their feet only being of use for walking. "Moreover, if the individuals of which I speak were impelled by the necessity of rising up and of looking far and wide, of endeavoring to stand erect, and of adopting this habit constantly from generation to generation, there is no doubt that their feet would gradually and imperceptibly assume a conformation adapted for an erect posture, that their legs would develop calves, and that these creatures would not afterwards walk as they do now, painfully on both hands and feet. "Also, if these same individuals should cease using their jaws for biting in self-defence, tearing or seizing, or using them like nippers in cutting leaves for food, and should they only be used in chewing food, there is no doubt that their facial angle would become higher, that their muzzle would become shorter and shorter, and that in the end this being entirely effaced, their incisor teeth would become vertical. "Now supposing that a race of _Quadrumana_, as for example the most perfect, had acquired, by habits constant in every individual, the structure I have just described, and the power of standing erect and of walking upright, and that as the result of this it had come to dominate the other races of animals, we should then conceive: "1. That this race farther advanced in its faculties, having arrived at the stage when it lords it over the others, will be spread over the surface of the globe in every suitable place; "2. That it will hunt the other higher races of animals and will struggle with them for preëminence (_lui disputer les biens de la terre_) and that it will force them to take refuge in regions which it does not occupy; "3. That being injured by the great multiplication of closely allied races, and having banished them into forests or other desert places, it will arrest the progress of improvement in their faculties, while its own self, the ruler of the region over which it spreads, will increase in population without hindrance on the part of others, and, living in numerous tribes, will in succession create new needs which should stimulate industry and gradually render still more perfect its means and powers; "4. That, finally, this preëminent race having acquired an absolute supremacy over all the others, there arose between it and the highest animals a difference and indeed a considerable interval. "Thus the most perfect race of _Quadrumana_ will have been enabled to become dominant, to change its habits as the result of the absolute dominion which it will have assumed over the others, and with its new needs, by progressively acquiring modifications in its structure and its new and numerous powers, to keep within due limits the most highly developed of the other races in the state to which they had advanced, and to create between it and these last very remarkable distinctions. "The Angola orang (_Simia troglodytes_ Lin.) is the highest animal; it is much more perfect than the orang of the Indies (_Simia satyrus_ Lin.), which is called the orang-outang, and, nevertheless, as regards their structure they are both very inferior to man in bodily faculties and intelligence. These animals often stand erect; but this attitude is not habitual, their organization not having been sufficiently modified, so that standing still (_station_) is painful for them. "It is known, from the accounts of travellers, especially in regard to the orang of the Indies, that when immediate danger obliges it to fly, it immediately falls on all fours. This betrays, they tell us, the true origin of this animal, since it is obliged to abandon the alien unaccustomed partially erect attitude which is thrust upon it. "Without doubt this attitude is foreign to it, since in its change of locality it makes less use of it, which shows that its organization is less adapted to it; but though it has become easier for man to stand up straight, is the erect posture wholly natural to him? "Although man, who, by his habits, maintained in the individuals of his species during a great series of generations, can stand erect only while changing from one place to another, this attitude is not less in his case a condition of fatigue, during which he is able to maintain himself in an upright position only during a limited time and with the aid of the contraction of several of his muscles. "If the vertebral column of the human body should form the axis of this body, and sustain the head in equilibrium, as also the other parts, the man standing would be in a state of rest. But who does not know that this is not so; that the head is not articulated at its centre of gravity; that the chest and stomach, as also the viscera which these cavities contain, weigh heavily almost entirely on the anterior part of the vertebral column; that the latter rests on an oblique base, etc.? Also, as M. Richerand observes, there is needed in standing a force active and watching without ceasing to prevent the body from falling over, the weight and disposition of parts tending to make the body fall forward. "After having developed the considerations regarding the standing posture of man, the same savant then expresses himself: 'The relative weight of the head, of the thoracic and abdominal viscera, tends therefore to throw it in front of the line, according to which all the parts of the body bear down on the ground sustaining it; a line which should be exactly perpendicular to this ground in order that the standing position may be perfect. The following fact supports this assertion: I have observed that infants with a large head, the stomach protruding and the viscera loaded with fat, accustom themselves with difficulty to stand up straight, and it is not until the end of their second year that they dare to surrender themselves to their proper forces; they stand subject to frequent falls and have a natural tendency to revert to the quadrupedal state.' (_Physiologie_, vol. ii., p. 268.) "This disposition of the parts which cause the erect position of man, being a state of activity, and consequently fatiguing, instead of being a state of rest, would then betray in him an origin analogous to that of the mammals, if his organization alone should be taken into consideration. "Now in order to follow, in all its particulars, the hypothesis presented in the beginning of these observations, it is fitting to add the following considerations: "The individuals of the dominant race previously mentioned, having taken possession of all the inhabitable places which were suitable for them, and having to a very considerable extent multiplied their necessities in proportion as the societies which they formed became more numerous, were able equally to increase their ideas, and consequently to feel the need of communicating them to their fellows. We conceive that there would arise the necessity of increasing and of varying in the same proportion the _signs_ adopted for the communication of these ideas. It is then evident that the members of this race would have to make continual efforts, and to employ every possible means in these efforts, to create, multiply, and render sufficiently varied the _signs_ which their ideas and their numerous wants would render necessary. "It is not so with any other animals; because, although the most perfect among them, such as the _Quadrumana_, live mostly in troops, since the eminent supremacy of the race mentioned they have remained stationary as regards the improvement of their faculties, having been driven out from everywhere and banished to wild, desert, usually restricted regions, whither, miserable and restless, they are incessantly constrained to fly and hide themselves. In this situation these animals no longer contract new needs, they acquire no new ideas; they have but a small number of them, and it is always the same ones which occupy their attention, and among these ideas there are very few which they have need of communicating to the other individuals of their species. There are, then, only very few different _signs_ which they employ among their fellows, so that some movements of the body or of certain of its parts, certain hisses and cries raised by the simple inflexions of the voice, suffice them. "On the contrary, the individuals of the dominant race already mentioned, having had need of multiplying the _signs_ for the rapid communication of their ideas, now become more and more numerous, and, no longer contented either with pantomimic signs or possible inflexions of their voice to represent this multitude of signs now become necessary, would succeed by different efforts in forming _articulated sounds_: at first they would use only a small number, conjointly with the inflexions of their voice; as the result they would multiply, vary, and perfect them, according to their increasing necessities, and according as they would be more accustomed to produce them. Indeed, the habitual exercise of their throat, their tongue, and their lips to make articulate sounds, will have eminently developed in them this faculty. "Hence for this particular race the origin of the wonderful power of _speech_; and as the distance between the regions where the individuals composing it would be spread would favor the corruption of the signs fitted to express each idea, from this arose the origin of languages, which must be everywhere diversified. "Then in this respect necessities alone would have accomplished everything; they would give origin to efforts; and the organs fitted for the articulation of sounds would be developed by their habitual use. "Such would be the reflections which might be made if man, considered here as the preëminent race in question, were distinguished from the animals only by his physical characters, and if his origin were not different from theirs." This is certainly, for the time it was written, an original, comprehensive, and bold attempt at explaining in a tentative way, or at least suggesting, the probable origin of man from some arboreal creature allied to the apes. It is as regards the actual evolutional steps supposed to have been taken by the simian ancestors of man, a more detailed and comprehensive hypothesis than that offered by Darwin in his _Descent of Man_,[197] which Lamarck has anticipated. Darwin does not refer to this theory of Lamarck, and seems to have entirely overlooked it, as have others since his time. The theory of the change from an arboreal life and climbing posture to an erect one, and the transformation of the hinder pair of hands into the feet of the erect human animal, remind us of the very probable hypothesis of Mr. Herbert Spencer, as to the modification of the quadrumanous posterior pair of hands to form the plantigrade feet of man. FOOTNOTES: [195] Author's italics. [196] "How much this unclean beast resembles man!"--_Ennius_. "Indeed, besides other resemblances the monkey has mammæ, a clitoris, nymphs, uterus, uvula, eye-lobes, nails, as in the human species; it also lacks a suspensory ligament of the neck. Is it not astonishing that man, endowed with wisdom, differs so little from such a disgusting animal!"--_Linnæus_. [197] Vol. i., chapter iv., pp. 135-151; ii., p. 372. CHAPTER XIX LAMARCK'S THOUGHTS ON MORALS, AND ON THE RELATION BETWEEN SCIENCE AND RELIGION One who has read the writings of the great French naturalist, who may be regarded as the founder of evolution, will readily realize that Lamarck's mind was essentially philosophic, comprehensive, and synthetic. He looked upon every problem in a large way. His breadth of view, his moral and intellectual strength, his equably developed nature, generous in its sympathies and aspiring in its tendencies, naturally led him to take a conservative position as to the relations between science and religion. He should, as may be inferred from his frequent references to the Author of nature, be regarded as a deist. When a very young man, he was for a time a friend of the erratic and gifted Rousseau, and was afterwards not unknown to Condorcet, the secretary of the French Academy of Sciences, so liberal in his views and so bitter an enemy of the Church; and though constantly in contact with the radical views and burning questions of that day, Lamarck throughout his life preserved his philosophic calm, and maintained his lofty tone and firm temper. We find no trace in his writings of sentiments other than the most elevated and inspiring, and we know that in character he was pure and sweet, self-sacrificing, self-denying, and free from self-assertion. The quotations from his _Philosophie zoologique_, published in 1809, given below, will show what were the results of his meditations on the relations between science and religion. Had his way of looking at this subject prevailed, how much misunderstanding and ill-feeling between theologians and savants would have been avoided! Had his spirit and breadth of view animated both parties, there would not have been the constant and needless opposition on the part of the Church to the grand results of scientific discovery and philosophy, or too hasty dogmatism and scepticism on the part of some scientists. In Lamarck, at the opening of the past century, we behold the spectacle of a man devoting over fifty years of his life to scientific research in biology, and insisting on the doctrine of spontaneous generation; of the immense length of geological time, so opposed to the views held by the Church; the evolution of plants and animals from a single germ, and even the origin of man from the apes, yet as earnestly claiming that nature has its Author who in the beginning established the order of things, giving the initial impulse to the laws of the universe. As Duval says, after quoting the passage given below: "Deux faits son à noter dans ce passage: d'une part, les termes dignes et conciliants dans lesquels Lamarck établit la part de la science et de la religion; cela vaut, mieux, même en tenant compte des différences d'epoques, que les abjurations de Buffon."[198] The passage quoted by M. Duval is the following one: "Surely nothing exists except by the will of the Sublime Author of all things. But can we not assign him laws in the execution of his will, and determine the method which he has followed in this respect? Has not his infinite power enabled him to create an order of things which has successively given existence to all that we see, as well as to that which exists and that of which we have no knowledge? As regards the decrees of this infinite wisdom, I have confined myself to the limits of a simple observer of nature."[199] In other places we find the following expressions: "There is then, for the animals as for the plants, an order which belongs to nature, and which results, as also the objects which this order makes exist, from the power which it has received from the SUPREME AUTHOR of all things. She is herself only the general and unchangeable order that this Sublime Author has created throughout, and only the totality of the general and special laws to which this order is subject. By these means, whose use it continues without change, it has given and will perpetually give existence to its productions; it varies and renews them unceasingly, and thus everywhere preserves the whole order which is the result of it."[200] ~ ~ ~ ~ ~ "To regard nature as eternal, and consequently as having existed from all time, is to me an abstract idea, baseless, limitless, improbable, and not satisfactory to my reason. Being unable to know anything positive in this respect, and having no means of reasoning on this subject, I much prefer to think that _all nature_ is only a result: hence, I suppose, and I am glad to admit it, a first cause, in a word, a supreme power which has given existence to nature, and which has made it in all respects what it is."[201] ~ ~ ~ ~ ~ "Nature, that immense totality of different beings and bodies, in every part of which exists an eternal circle of movements and changes regulated by law; totality alone unchangeable, so long as it pleases its SUBLIME AUTHOR to cause its existence, should be regarded as a whole constituted by its parts, for a purpose which its Author alone knows, and not exclusively for any one of them. "Each part is necessarily obliged to change, and to cease to be one in order to constitute another, with interests opposed to those of all; and if it has the power of reasoning it finds this whole imperfect. In reality, however, this whole is perfect and completely fulfils the end for which it was designed."[202] Lamarck's work on general philosophy[203] was written near the end of his life, in 1820. He begins his "Discours préliminaire" by referring to the sudden loss of his eyesight, his work on the invertebrate animals being thereby interrupted. The book was, he says, "rapidly" dictated to his daughter, and the ease with which he dictated was due, he says, to his long-continued habit of meditating on the facts he had observed. In the "Principes primordiaux" he considers man as the only being who has the power of observing nature, and the only one who has perceived the necessity of recognizing a superior and only cause, creator of the order of the wonders of the world of life. By this he is led to raise his thoughts to the _Supreme Author_ of all that exists. "In the creation of his works, and especially those we can observe, this omnipotent Being has undoubtedly been the ruling power in pursuing the method which has pleased him, namely, his will has been: "Either to create instantaneously and separately every particular living being observed by us, to personally care for and watch over them in all their changes, their movements, or their actions, to unremittingly care for each one separately, and by the exercise of his supreme will to regulate all their life; "Or to reduce his creations to a small number, and among these, to institute an order of things general and continuous, pervaded by ceaseless activity (_mouvement_), especially subject to laws by means of which all the organisms of whatever nature, all the changes they undergo, all the peculiarities they present, and all the phenomena that many of them exhibit, may be produced. "In regard to these two modes of execution, if observation taught us nothing we could not form any opinion which would be well grounded. But it is not so; we distinctly see that there exists an order of things truly created (_véritablement créé_), as unchangeable as its author allows, acting on matter alone, and which possesses the power of producing all visible beings, of executing all the changes, all the modifications, even the extinctions, so also the renewals or recreations that we observe among them. It is to this order of things that we have given the name of _nature_. The Supreme Author of all that exists is, then, the immediate creator of matter as also of nature, but he is only indirectly the creator of what nature can produce. "The end that God has proposed to himself in creating matter, which forms the basis of all bodies, and nature, which divides (_divise_) this matter, forms the bodies, makes them vary, modifies them, changes them, and renews them in different ways, can be easily known to us; for the Supreme Being cannot meet with any obstacle to his will in the execution of his works; the general results of these works are necessarily the object he had in view. Thus this end could be no other than the existence of nature, of which matter alone forms the sphere, and should not be that causing the creation of any special being. "Do we find in the two objects created, _i.e._, _matter_ and _nature_, the source of the good and evil which have almost always been thought to exist in the events of this world? To this question I shall answer that good and evil are only relative to particular objects, that they never affect by their temporary existence the general result expected (_prévu_), and that for the end which the Creator designed, there is in reality neither good nor evil, because everything in nature perfectly fulfils its object. "Has God limited his creations to the existence of only matter and nature? This question is vain, and should remain without an answer on our part; because, being reduced to knowing anything only through observation, and to bodies alone, also to what concerns them, these being for us the only observable objects, it would be rash to speak affirmatively or negatively on this subject. "What is a spiritual being? It is what, with the aid of the imagination, one would naturally suppose (_l'on vaudra supposer_). Indeed, it is only by means of opposing that which is material that we can form the idea of spirit; but as this hypothetical being is not in the category of objects which it is possible for us to observe, we do not know how to take cognizance of it. The idea that we have of it is absolutely without base. "We only know physical objects and only objects relative to these beings (_êtres_): such is the condition of our nature. If our thoughts, our reasonings, our principles have been considered as metaphysical objects, these objects, then, are not beings (_êtres_). They are only relations or consequences of relations (_rapports_), or only results of observed laws. "We know that relations are distinguished as general and special. Among these last are regarded those of nature, form, dimension, solidity, size, quantity, resemblance, and difference; and if we add to these objects the being observed and the consideration of known laws, as also that of conventional objects, we shall have all the materials on which our thoughts are based. "Thus being able to observe only the phenomena of nature, as well as the laws which regulate these phenomena, also the products of these last, in a word, only bodies (_corps_) and what concerns them, all that which immediately proceeds from supreme power is incomprehensible to us, as it itself [_i.e._, supreme power] is to our minds. To create, or to make anything out of nothing, this is an idea we cannot conceive of, for the reason that in all that we can know, we do not find any model which represents it. GOD alone, then, can create, while nature can only produce. We must suppose that, in his creations, the Divinity is not restricted to the use of any time, while, on the other hand, nature can effect nothing without the aid of long periods of time." Without translating more of this remarkable book, which is very rare, much less known than the _Philosophie zoologique_, the spirit of the remainder may be imagined from the foregoing extracts. The author refers to the numerous evils resulting from ignorance, false knowledge, lack of judgment, abuse of power, demonstrating the necessity of our confining ourselves within the circle of the objects presented by nature, and never to go beyond them if we do not wish to fall into error, because the profound study of nature and of the organization of man alone, and the exact observation of facts alone, will reveal to us "the truths most important for us to know," in order to avoid the vexations, the perfidies, the injustices, and the oppressions of all sorts, and "incalculable disorders" which arise in the social body. In this way only shall we discover and acquire the means of obtaining the enjoyment of the advantages which we have a right to expect from our state of civilization. The author endeavors to state what science can and should render to society. He dwells on the sources from which man has drawn the knowledge which he possesses, and from which he can obtain many others--sources the totality of which constitutes for him the field of realities. Lamarck also in this work has built up a system for moral philosophy. Self-love, he says, perfectly regulated, gives rise: 1. To moral force which characterizes the laborious man, so that the length and difficulties of a useful work do not repel him. 2. To the courage of him who, knowing the danger, exposes himself when he sees that this would be useful. 3. To love of wisdom. Wisdom, according to Lamarck, consists in the observance of a certain number of rules or virtues. These we cite in a slightly abridged form. Love of truth in all things; the need of improving one's mind; moderation in desires; decorum in all actions; a wise reserve in unessential wants; indulgence, toleration, humanity, good will towards all men; love of the public good and of all that is necessary to our fellows; contempt for weakness; a kind of severity towards one's self which preserves us from that multitude of artificial wants enslaving those who give up to them; resignation and, if possible, moral impassibility in suffering reverses, injustices, oppression, and losses; respect for order, for public institutions, civil authorities, laws, morality, and religion. The practice of these maxims and virtues, says Lamarck, characterizes true philosophy. And it may be added that no one practised these virtues more than Lamarck. Like Cuvier's, his life was blameless, and though he lived a most retired life, and was not called upon to fill any public station other than his chair of zoölogy at the Jardin des Plantes, we may feel sure that he had the qualities of courage, independence, and patriotism which would have rendered such a career most useful to his country. As Bourguin eloquently asserts: "Lamarck was the brave man who never deserted a dangerous post, the laborious man who never hesitated to meet any difficulty, the investigating spirit, firm in his convictions, tolerant of the opinions of others, the simple man, moderate in all things, the enemy of weakness, devoted to the public good, imperturbable under the attaints of fortune, of suffering, and of unjust and passionate attacks." FOOTNOTES: [198] Mathias Duval: "Le transformiste français Lamarck," _Bulletin de la Société d'Anthropologie de Paris_, xii., 1889, p. 345. [199] _Philosophie zoologique_, p. 56. [200] _Loc. cit._, i., p. 113. [201] _Loc. cit._, i., p. 361. [202] _Loc. cit._, ii., p. 465. [203] _Système analytique des Connaissances de l'Homme_, etc. CHAPTER XX THE RELATIONS BETWEEN LAMARCKISM AND DARWINISM; NEOLAMARCKISM Since the appearance of Darwin's _Origin of Species_, and after the great naturalist had converted the world to a belief in the general doctrine of evolution, there has arisen in the minds of many working naturalists a conviction that natural selection, or Darwinism as such, is only one of other evolutionary factors; while there are some who entirely reject the selective principle. Darwin, moreover, assumed a tendency to fortuitous variation, and did not attempt to explain its cause. Fully persuaded that he had discovered the most efficient and practically sole cause of the origin of species, he carried the doctrine to its extreme limits, and after over twenty years of observation and experiment along this single line, pushing entirely aside the Erasmus-Darwin and Lamarckian factors of change of environment, though occasionally acknowledging the value of use and disuse, he triumphantly broke over all opposition, and lived to see his doctrine generally accepted. He had besides the support of some of the strongest men in science: Wallace in a twin paper advocated the same views; Spencer, Lyell, Huxley, Hooker, Haeckel, Bates, Semper, Wyman, Gray, Leidy, and other representative men more or less endorsed Darwin's views, or at least some form of evolution, and owing largely to their efforts in scientific circles and in the popular press, the doctrine of descent rapidly permeated every avenue of thought and became generally accepted. Meanwhile, the general doctrine of evolution thus proved, and the "survival of the fittest" an accomplished fact, the next step was to ascertain "how," as Cope asked, "the fittest originated?" It was felt by some that natural selection alone was not adequate to explain the first steps in the origin of genera, families, orders, classes, and branches or phyla. It was perceived by some that natural selection by itself was not a _vera causa_, an efficient agent, but was passive, and rather expressed the results of the operations of a series of factors. The transforming should naturally precede the action of the selective agencies. We were, then, in our quest for the factors of organic evolution, obliged to fall back on the action of the physico-chemical forces such as light, or its absence, heat, cold, change of climate; and the physiological agencies of food, or in other words on changes in the physical environment, as well as in the biological environment. Lamarck was the first one who, owing to his many years' training in systematic botany and zoölogy, and his philosophic breadth, had stated more fully and authoritatively than any one else the results of changes in the action of the primary factors of evolution. Hence a return on the part of many in Europe, and especially in America, to Lamarckism or its modern form, Neolamarckism. Lamarck had already, so far as he could without a knowledge of modern morphology, embryology, cytology, and histology, suggested those fundamental principles of transformism on which rests the selective principle. Had his works been more accessible, or, where available, more carefully read, and his views more fairly represented; had he been favored in his lifetime by a single supporter, rather than been unjustly criticised by Cuvier, science would have made more rapid progress, for it is an axiomatic truth that the general acceptance of a working evolutionary theory has given a vast impetus to biology. We will now give a brief historical summary of the history of opinion held by Lamarckians regarding the causes of the "origin of the fittest," the rise of variations, and the appearance of a population of plant and animal forms sufficiently extensive and differentiated to allow for the play of the competitive forces, and of the more passive selective agencies which began to operate in pre-cambrian times, or as soon as the earth became fitted for the existence of living beings. The first writer after Lamarck to work along the lines he laid down was Mr. Herbert Spencer. In 1866-71, in his epochal and remarkably suggestive _Principles of Biology_, the doctrine of use and disuse is implicated in his statements as to the effects of motion on structure in general;[204] and in his theory as to the origin of the notochord, and of the segmentation of the vertebral column and the segmental arrangement of the muscles by muscular strains,[205] he laid the foundations for future work along this line. He also drew attention in the same work to the complementary development of parts, and likewise instanced the decreased size of the jaws in the civilized races of mankind, as a change not accounted for by the natural selection of favorable variations.[206] In fact, this work is largely based on the Lamarckian principles, as affording the basis for the action of natural selection, and thirty years later we find him affirming: "The direct action of the medium was the primordial factor of organic evolution."[207] In his well-known essay on "The Inadequacy of Natural Selection" (1893) the great philosopher, with his accustomed vigor and force, criticises the arguments of those who rely too exclusively on Darwinism alone, and especially Neodarwinism, as a sufficient factor to account for the origin of special structures as well as species. The first German author to appreciate the value of the Lamarckian factors was that fertile and comprehensive philosopher and investigator Ernst Haeckel, who also harmonized Lamarckism and Darwinism in these words: "We should, on account of the grand proofs just enumerated, have to adopt Lamarck's Theory of Descent for the explanation of biological phenomena, even if we did not possess Darwin's Theory of Selection. The one is so completely and _directly proved_ by the other, and established by mechanical causes, that there remains nothing to be desired. The laws of _Inheritance_ and _Adaptation_ are universally acknowledged physiological facts, the former traceable to propagation, the latter to the _nutrition_ of organisms. On the other hand, the _struggle for existence_ is a _biological_ fact, which with mathematical necessity follows from the general disproportion between the average number of organic individuals and the numerical excess of their germs."[208] A number of American naturalists at about the same date, as the result of studies in different directions, unbiassed by a too firm belief in the efficacy of natural selection, and relying on the inductive method alone, worked away at the evidence in favor of the primary factors of evolution along Lamarckian lines, though quite independently, for at first neither Hyatt nor Cope had read Lamarck's writings. In 1866 Professor A. Hyatt published the first of a series of classic memoirs on the genetic relations of the fossil cephalopods. His labors, so rich in results, have now been carried on for forty years, and are supplemented by careful, prolonged work on the sponges, on the tertiary shells of Steinheim, and on the land shells of the Hawaiian Islands. His first paper was on the parallelism between the different stages of life in the individual and those of the ammonites, carrying out D'Orbigny's discovery of embryonic, youthful, adult, and old-age stages in ammonites,[209] and showing that these forms are due to an acceleration of growth in the mature forms, and a retardation in the senile forms. In a memoir on the "Biological Relations of the Jurassic Ammonites,"[210] he assigns the causes of the progressive changes in these forms, the origination of new genera, and the production of young, mature, and senile forms to "the favorable nature of the physical surroundings, primarily producing characteristic changes which become perpetuated and increased by inheritance within the group." The study of the modifications of the tertiary forms of Planorbis at Steinheim, begun by Hilgendorf, led among others (nine in all) to the following conclusions: "First, that the unsymmetrical spiral forms of the shells of these and of all the Mollusca probably resulted from the action of the laws of heredity, modified by gravitation. "Second, that there are many characteristics in these shells and in other groups, which are due solely to the uniform action of the physical influence of the immediate surroundings, varying with every change of locality, but constant and uniform within each locality. "Third, that the Darwinian law of Natural Selection does not explain these relations, but applies only to the first stages in the establishment of the differences between forms or species in the same locality. That its office is to fix these in the organization and bring them within the reach of the laws of heredity." These views we find reiterated in his later palæontological papers. Hyatt's views on acceleration were adopted by Neumayr.[211] Waagen,[212] from his studies on the Jurassic cephalopods, concludes that the factors in the evolution of these forms were changes in external conditions, geographical isolation, competition, and that the fundamental law was not that of Darwin, but "the law of development." Hyatt has also shown that at first evolution was rapid. "The evolution is a purely mechanical problem in which the action of the habitat is the working agent of all the major changes; first acting upon the adult stages, as a rule, and then through heredity upon the earlier stages in successive generations." He also shows that as the primitive forms migrated and occupied new, before barren, areas, where they met with new conditions, the organisms "changed their habits and structures rapidly to accord with these new conditions."[213] While the palæontological facts afford complete and abundant proofs of the modifying action of changes in the environment, Hyatt, in 1877, from his studies on sponges,[214] shows that the origin of their endless forms "can only be explained by the action of physical surroundings directly working upon the organization and producing by such direct action the modifications or common variations above described." Mr. A. Agassiz remarks that the effect of the nature of the bottom of the sea on sponges and rhizopods "is an all-important factor in modifying the organism."[215] While Hyatt's studies were chiefly on the ammonites, molluscs, and existing sponges, Cope was meanwhile at work on the batrachians. His _Origin of Genera_ appeared shortly after Hyatt's first paper, but in the same year (1866). This was followed by a series of remarkably suggestive essays based on his extensive palæontological work, which are in part reprinted in his _Origin of the Fittest_ (1887); while in his epoch-making book, _The Primary Factors of Organic Evolution_ (1896), we have in a condensed shape a clear exposition of some of the Lamarckian factors in their modern Neolamarckian form. In the Introduction, p. 9, he remarks: "In these papers by Professor Hyatt and myself is found the first attempt to show by concrete examples of natural taxonomy that the variations that result in evolution are not multifarious or promiscuous, but definite and direct, contrary to the method which seeks no origin for variations other than natural selection. In other words, these publications constitute the first essays in systematic evolution that appeared. By the discovery of the paleontologic succession of modifications of the articulations of the vertebrate, and especially mammalian, skeleton, I first furnished an actual demonstration of the reality of the Lamarckian factor of use, or motion, as friction, impact, and strain, as an efficient cause of evolution."[216] The discussion in Cope's work of kinetogenesis, or of the effects of use and disuse, affords an extensive series of facts in support of these factors of Lamarck's. As these two books are accessible to every one, we need only refer the reader to them as storehouses of facts bearing on Neolamarckism. The present writer, from a study of the development and anatomy of Limulus and of Arthropod ancestry, was early (1870)[217] led to adopt Lamarckian views in preference to the theory of Natural Selection, which never seemed to him adequate or sufficiently comprehensive to explain the origin of variations. In the following year,[218] from a study of the insects and other animals of Mammoth Cave, we claimed that "the characters separating the genera and species of animals are those inherited from adults, modified by their physical surroundings and adaptations to changing conditions of life, inducing certain alterations in parts which have been transmitted with more or less rapidity, and become finally fixed and habitual." In an essay entitled "The Ancestry of Insects"[219] (1873) we adopted the Lamarckian factors of change of habits and environment, of use and disuse, to account for the origin of the appendages, while we attributed the origin of the metamorphoses of insects to change of habits or of the temperature of the seasons and of climates, particularly the change in the earth's climates from the earlier ages of the globe, "when the temperature of the earth was nearly the same the world over, to the times of the present distribution of heat and cold in zones." From further studies on cave animals, published in 1877,[220] we wrote as follows: "In the production of these cave species, the exceptional phenomena of darkness, want of sufficient food, and unvarying temperature, have been plainly enough _veræ causæ_. To say that the principle of natural selection accounts for the change of structure is no explanation of the phenomena; the phrase has to the mind of the writer no meaning in connection with the production of these cave forms, and has as little meaning in accounting for the origination of species and genera in general. Darwin's phrase 'natural selection,' or Herbert Spencer's term 'survival of the fittest,' expresses simply the final result, while the process of the origination of the new forms which have survived, or been selected by nature, is to be explained by the action of the physical environments of the animals coupled with inheritance-force. It has always appeared to the writer that the phrases quoted above have been misused to state the cause, when they simply express the result of the action of a chain of causes which we may, with Herbert Spencer, call the 'environment' of the organism undergoing modification; and thus a form of Lamarckianism, greatly modified by recent scientific discoveries, seems to meet most of the difficulties which arise in accounting for the origination of species and higher groups of organisms. Certainly 'natural selection' or the 'survival of the fittest' is not a _vera causa_, though the 'struggle for existence' may show us the causes which have led to the _preservation_ of species, while changes in the environment of the organism may satisfactorily account for the original tendency to variation assumed by Mr. Darwin as the starting-point where natural selection begins to act." In our work on _The Cave Animals of North America_,[221] after stating that Darwin in his _Origin of Species_ attributed the loss of eyes "wholly to disuse," remarking (p. 142) that after the more or less perfect obliteration of the eyes, "natural selection will often have effected other changes, such as an increase in the length of the antennæ or palpi, as a compensation for blindness," we then summed up as follows the causes of the production of cave faunæ in general: "1. Change in environment from light, even partial, to twilight or total darkness, and involving diminution of food, and compensation for the loss of certain organs by the hypertrophy of others. "2. Disuse of certain organs. "3. Adaptation, enabling the more plastic forms to survive and perpetuate their stock. "4. Isolation, preventing intercrossing with out-of-door forms, thus insuring the permanency of the new varieties, species, or genera. "5. Heredity, operating to secure for the future the permanence of the newly originated forms as long as the physical conditions remain the same. "Natural selection perhaps expresses the total result of the working of these five factors rather than being an efficient cause in itself, or at least constitutes the last term in a series of causes. Hence Lamarckism in a modern form, or as we have termed it, Neolamarckism, seems to us to be nearer the truth than Darwinism proper or natural selection."[222] In an attempt to apply Lamarck's principle of the origin of the spines and horns of caterpillars and other insects as well as other animals to the result of external stimuli,[223] we had not then read what he says on the subject. (See p. 316.) Having, however, been led to examine into the matter, from the views held by recent observers, especially Henslow, and it appearing that Lamarck was substantially correct in supposing that the blood (his "fluids") would flow to parts on the exposed portions of the body and thus cause the origin of horns, on the principle of the saying, "_ubi irritatio, ibi affluxus_," we came to the following conclusions: "The Lamarckian factors (1) change (both direct and indirect) in the _milieu_, (2) need, and (3) habit, and the now generally adopted principle that a change of function induces change in organs,[224] and in some or many cases actually induces the hypertrophy and specialization of what otherwise would be indifferent parts or organs;--these factors are all-important in the evolution of the colors, ornaments, and outgrowths from the cuticle of caterpillars." Our present views as to the relations between the Lamarckian factors and the Darwinian one of natural selection are shown by the following summary at the end of this essay. "1. The more prominent tubercles, and spines or bristles arising from them, are hypertrophied piliferous warts, the warts, with the seta or hair which they bear, being common to all caterpillars. "2. The hypertrophy or enlargement was probably [we should rather say _possibly_] primarily due to a change of station from herbs to trees, involving better air, a more equable temperature, perhaps a different and better food. "3. The enlarged and specialized tubercles developed more rapidly on certain segments than on others, especially the more prominent segments, because the nutritive fluids would tend more freely to supply parts most exposed to external stimuli. "4. The stimuli were in great part due to the visits of insects and birds, resulting in a mimicry of the spines and projections on the trees; the colors (lines and spots) were due to light or shade, with the general result of protective mimicry, or adaptation to tree-life. "5. As the result of some unknown factor some of the hypodermic cells at the base of the spines became in certain forms specialized so as to secrete a poisonous fluid. "6. After such primitive forms, members of different families, had become established on trees, a process of arboreal segregation or isolation would set in, and intercrossing with low-feeders would cease. "7. Heredity, or the unknown factors of which heredity is the result, would go on uninterruptedly, the result being a succession of generations perfectly adapted to arboreal life. "8. Finally the conservative agency of natural selection operates constantly, tending towards the preservation of the new varieties, species, and genera, and would not cease to act, in a given direction, so long as the environment remained the same. "9. Thus in order to account for the origin of a species, genus, family, order, or even a class, the first steps, causing the origination of variations, were in the beginning due to the primary (direct and indirect) factors of evolution (Neolamarckism), and the final stages were due to the secondary factors, segregation and natural selection (Darwinism)." From a late essay[225] we take the following extracts explaining our views: "In seeking to explain the causes of a metamorphosis in animals, one is compelled to go back to the primary factors of organic evolution, such as the change of environment, whether the factors be cosmical (gravity), physical changes in temperature, effects of increased or diminished light and shade, under- or over-nutrition, and the changes resulting from the presence or absence of enemies, or from isolation. The action of these factors, whether direct or indirect, is obvious, when we try to explain the origin or causes of the more marked metamorphoses of animals. Then come in the other Lamarckian factors of use and disuse, new needs resulting in new modes of life, habits, or functions, which bring about the origination, development, and perfection of new organs, as in new species and genera, etc., or which in metamorphic forms may result in a greater increase in the number of, and an exaggeration of the features characterizing the stages of larval life. "VI. _The Adequacy of Neolamarckism_. "It is not to be denied that in many instances all through the ceaseless operation of these fundamental factors there is going on a process of sifting or of selection of forms best adapted to their surroundings, and best fitted to survive, but this factor, though important, is quite subordinate to the initial causes of variation, and of metamorphic changes. "Neolamarckism,[226] as we understand this doctrine, has for its foundation a combination of the factors suggested by the Buffon and Geoffroy St. Hilaire school, which insisted on the direct action of the _milieu_, and of Lamarck, who relied both on the direct (plants and lowest animals) and on the indirect action of the environment, adding the important factors of need and of change of habits resulting either in the atrophy or in the development of organs by disuse or use, with the addition of the hereditary transmission of characters acquired in the lifetime of the individual. "Lamarck's views, owing to the early date of his work, which was published in 1809, before the foundation of the sciences of embryology, cytology, palæontology, zoögeography, and in short all that distinguishes modern biology, were necessarily somewhat crude, though the fundamental factors he suggested are those still invoked by all thinkers of Lamarckian tendencies. "Neolamarckism gathers up and makes use of the factors both of the St. Hilaire and Lamarckian schools, as containing the more fundamental causes of variation, and adds those of geographical isolation or segregation (Wagner and Gulick), the effects of gravity, the effects of currents of air and of water, of fixed or sedentary as opposed to active modes of life, the results of strains and impacts (Ryder, Cope, and Osborn), the principle of change of function as inducing the formation of new structures (Dohrn), the effects of parasitism, commensalism, and of symbiosis--in short, the biological environment; together with geological extinction, natural and sexual selection, and hybridity. "It is to be observed that the Neolamarckian in relying mainly on these factors does not overlook the value of natural selection as a guiding principle, and which began to act as soon as the world became stocked with the initial forms of life, but he simply seeks to assign this principle to its proper position in the hierarchy of factors. "Natural selection, as the writer from the first has insisted, is not a _vera causa_, an initial or impelling cause in the origination of new species and genera. It does not start the ball in motion; it only, so to speak, guides its movements down this or that incline. It is the expression, like that of "the survival of the fittest" of Herbert Spencer, of the results of the combined operation of the more fundamental factors. In certain cases we cannot see any room for its action; in some others we cannot at present explain the origin of species in any other way. Its action increased in proportion as the world became more and more crowded with diverse forms, and when the struggle for existence had become more unceasing and intense. It certainly cannot account for the origination of the different branches, classes, or orders of organized beings. It in the main simply corresponds to artificial selection; in the latter case, man selects forms already produced by domestication, the latter affording sports and varieties due to change in the surroundings, that is, soil, climate, food, and other physical features, as well as education. "In the case also of heredity, which began to operate as soon as the earliest life forms appeared, we have at the outset to invoke the principle of the heredity of characters acquired during the lifetime of lowest organisms. "Finally, it is noticeable that when one is overmastered by the dogma of natural selection he is apt, perhaps unconsciously, to give up all effort to work out the factors of evolution, or to seek to work out this or that cause of variation. Trusting too implicitly to the supposed _vera causa_, one may close his eyes to the effects of change of environment or to the necessity of constant attempts to discover the real cause of this or that variation, the reduction or increase in size of this or that organ; or become insensible to the value of experiments. Were the dogma of natural selection to become universally accepted, further progress would cease, and biology would tend to relapse into a stage of atrophy and degeneration. On the other hand, a revival of Lamarckism in its modern form, and a critical and doubting attitude towards natural selection as an efficient cause, will keep alive discussion and investigation, and especially, if resort be had to experimentation, will carry up to a higher plane the status of philosophical biology." Although now the leader of the Neodarwinians, and fully assured of the "all-sufficiency" of natural selection, the veteran biologist Weismann, whose earlier works were such epoch-making contributions to insect embryology, was, when active as an investigator, a strong advocate of the Lamarckian factors. In his masterly work, _Studies in the Theory of Descent_[227] (1875), although accepting Darwin's principle of natural selection, he also relied on "the transforming influence of direct action as upheld by Lamarck," although he adds, "its extent cannot as yet be estimated with any certainty." He concluded from his studies in seasonal dimorphism, "that differences of specific value can originate through the direct action of external conditions of life only." While conceding that sexual selection plays a very important part in the markings and coloring of butterflies, he adds "that a change produced directly by climate may be still further increased by sexual selection." He also inquired into the origin of variability, and held that it can be elucidated by seasonal dimorphism. He thus formulated the chief results of his investigations: "A species is only caused to change through the influence of changing external conditions of life, this change being in a fixed direction which entirely depends on the physical nature of the varying organism, and is different in different species or even in the two sexes of the same species." The influence of changes of climate on variation has been studied to especial advantage in North America, owing to its great extent, and to the fact that its territory ranges from the polar to the tropical regions, and from the Atlantic to the Pacific Ocean. As respects climatic variation in birds, Professor Baird first took up the inquiry, which was greatly extended, with especial relation to the formation of local varieties, by Dr. J. A. Allen,[228] who was the first to ascertain by careful measurements, and by a study of the difference in plumage and pelage of individuals inhabiting distant portions of a common habitat, the variations due to climatic and local causes. "That varieties," he says, "may and do arise by the action of climatic influences, and pass on to become species; and that species become, in like manner, differentiated into genera, is abundantly indicated by the facts of geographical distribution, and the obvious relation of local forms to the conditions of environment. The present more or less unstable condition of the circumstances surrounding organic beings, together with the known mutations of climate our planet has undergone in past geological ages, point clearly to the agency of physical conditions as one of the chief factors in the evolution of new forms of life. So long as the environing conditions remain stable, just so long will permanency of character be maintained; but let changes occur, however gradual or minute, and differentiations begin." He inclines to regard the modifications as due rather to the direct action of the conditions of environment than to "the round-about process of natural selection." He also admits that change of habits and food, use and disuse, are factors. The same kind of inquiry, though on far less complete data, was extended by the present writer[229] in 1873 to the moths, careful measurements of twenty-five species of geometrid moths common to the Atlantic and Pacific coasts of North America showing that there is an increase in size and variation in shape of the wings, and in some cases in color, in the Pacific Coast over Eastern or Atlantic Coast individuals of the same species, the differences being attributed to the action of climatic causes. The same law holds good in the few Notodontian moths common to both sides of our continent. Similar studies, the results depending on careful measurements of many individuals, have recently been made by C. H. Eigenmann (1895-96), W. J. Moenkhaus (1896), and H. C. Bumpus (1896-98). The discoveries of Owen, Gaudry, Huxley, Kowalevsky, Cope, Marsh, Filhol, Osborn, Scott, Wortmann, and many others, abundantly prove that the lines of vertebrate descent must have been the result of the action of the primary factors of organic evolution, including the principles of migration, isolation, and competition; the selective principle being secondary and preservative rather than originative. Important contributions to dynamic evolution or kinetogenesis are the essays of Cope, Ryder, Dall, Osborn, Jackson, Scott, and Wortmann. Ryder began in 1877 to publish a series of remarkably suggestive essays on the "mechanical genesis," through strains, of the vertebrate limbs and teeth, including the causes of the reduction of digits. In discussing the origin of the great development of the incisor teeth of rodents, he suggested that "the more severe strains to which they were subjected by enforced or intelligently assumed changes of habit, were the initiatory agents in causing them to assume their present forms, such forms as were best adapted to resist the greatest strains without breaking."[230] He afterwards[231] claimed that the articulations of the cartilaginous fin-rays of the trout (_Salmo fontinalis_) are due to the mechanical strains experienced by the rays in use as motors of the body of the fish in the water. In the line of inquiry opened up by Cope and by Ryder are the essays of Osborn[232] on the mechanical causes for the displacement of the elements of the feet in the mammals, and the phylogeny of the teeth. Also Professor W. B. Scott thus expresses the results of his studies:[233] "To sum up the results of our examination of certain series of fossil mammals, one sees clearly that transformation, whether in the way of the addition of new parts or the reduction of those already present, acts just _as if_ the direct action of the environment and the habits of the animal were the efficient cause of the change, and any explanation which excludes the direct action of such agencies is confronted by the difficulty of an immense number of the most striking coincidences.... So far as I can see, the theory of determinate variations and of use-inheritance is not antagonistic but supplementary to natural selection, the latter theory attempting no explanation of the _causes_ of variation. Nor is it pretended for a moment that use and disuse are the sole or even the chief factors in variation." As early as 1868 the Lamarckian factor of isolation, due to migration into new regions, was greatly extended, and shown by Moritz Wagner[234] to be a most important agent in the limitation and fixation of varieties and species. "Darwin's work," he says, "neither satisfactorily explains the external cause which gives the first impulse to increased individual variability, and consequently to natural selection, nor that condition which, in connection with a certain advantage in the struggle for life, renders the new characteristics indispensable. The latter is, according to my conviction, solely fulfilled by the voluntary or passive migration of organisms and colonization, which depends in a great measure upon the configuration of the country; so that only under favorable conditions would the home of a new species be founded." This was succeeded by Rev. J. T. Gulick's profound essays "On Diversity of Evolution under One Set of External Conditions"[235] (1872), and on "Divergent Evolution through Cumulative Segregation"[236] (1887). These and later papers are based on his studies on the land shells of the Hawaiian Islands. The cause of their extreme diversity of local species is, he claims, not due to climatic conditions, food, enemies, or to natural selection, but to the action of what he calls the "law of segregation." Fifteen years later Mr. Romanes published his theory of physiological selection, which covered much the same ground. A very strong little book by an ornithologist of wide experience, Charles Dixon,[237] and refreshing to read, since it is packed with facts, is Lamarckian throughout. The chief factor in the formation of local species is, he thinks, isolation; the others are climatic influences (especially the glacial period), use and disuse, and sexual selection as well as chemical agency. Dixon insists on the "vast importance of isolation in the modification of many forms of life, without the assistance of natural selection." Again he says: "Natural selection, as has often been remarked, can only preserve a beneficial variation--it cannot originate it, it is not a cause of variation; on the other hand, the use or disuse of organs is a direct cause of variation, and can furnish natural selection with abundance of material to work upon" (p. 49). The book, like the papers of Allen, Ridgway, Gulick, and others, shows the value of isolation or segregation in special areas as a factor in the origination of varieties and species, the result being the prevention of interbreeding, which would otherwise swamp the incipient varieties. Here might be cited Delboeuf's law:[238] "When a modification is produced in a very small number of individuals, this modification, even were it advantageous, would be destroyed by heredity, as the favored individuals would be obliged to unite with the unmodified individuals. _Il n'en est rien, cependant._ However great may be the number of forms similar to it, and however small may be the number of dissimilar individuals which would give rise to an isolated individual, we can always, while admitting that the different generations are propagated under the same conditions, meet with a number of generations at the end of which the sum total of the modified individuals will surpass that of the unmodified individuals." Giard adds that this law is capable of mathematical demonstration. "Thus the continuity or even the periodicity of action of a primary factor, such, for example, as a variation of the _milieu_, shows us the necessary and sufficient condition under which a variety or species originates without the aid of any secondary factor." Semper,[239] an eminent zoölogist and morphologist, who also was the first (in 1863) to criticise Darwin's theory of the mode of formation of coral atolls, though not referring to Lamarck, published a strong, catholic, and original book, which is in general essentially Lamarckian, while not undervaluing Darwin's principle of natural selection. "It appears to me," he says, in the preface, "that of all the properties of the animal organism, Variability is that which may first and most easily be traced by exact investigation to its efficient causes." "By a rearrangement of the materials of his argument, however, we obtain, as I conceive, convincing proof that external conditions can exert not only a very powerful selective force, but a transforming one as well, although it must be the more limited of the two. "An organ no longer needed for its original purpose may adapt itself to the altered circumstances, and alter correspondingly if it contains within itself, as I have explained above, the elements of such a change. Then the influence exerted by the changed conditions will be _transforming_, not _selective_. "This last view may seem somewhat bold to those readers who know that Darwin, in his theory of selection, has almost entirely set aside the direct transforming influence of external circumstances. Yet he seems latterly to be disposed to admit that he had undervalued the transforming as well as the selective influence of external conditions; and it seems to me that his objection to the idea of such an influence rested essentially on the method of his argument, which seemed indispensable for setting his theory of selection and his hypothesis as to the transformation of species in a clear light and on a firm footing" (p. 37). Dr. H. de Varigny has carried on much farther the kind of experiments begun by Semper. In his _Experimental Evolution_ he employs the Lamarckian factors of environment and use and disuse, regarding the selective factors as secondary. The Lamarckian factors are also depended upon by the late Professor Eimer in his works on the variation of the wall-lizard and on the markings of birds and mammals (1881-88), his final views being comprised in his general work.[240] The essence of his point of view may be seen by the following quotation: "According to my conception, the physical and chemical changes which organisms experience during life through the action of the environment, through light or want of light, air, warmth, cold, water, moisture, food, etc., and which they transmit by heredity, are the primary elements in the production of the manifold variety of the organic world, and in the origin of species. From the materials thus supplied the struggle for existence makes its selection. These changes, however, express themselves simply as growth" (p. 22). In a later paper[241] Eimer proposes the term "orthogenesis," or direct development, in rigorous conformity to law, in a few definite directions. Although this is simply and wholly Lamarckism, Eimer claims that it is not, "for," he strangely enough says, "Lamarck ascribed no efficiency whatever to the effects of outward influences on the animal body, and very little to their effects upon vegetable organisms." Whereas if he had read his Lamarck carefully, he would have seen that the French evolutionist distinctly states that the environment acts directly on plants and the lower animals, but indirectly on those animals with a brain, meaning the higher vertebrates. The same anti-selection views are held by Eimer's pupil, Piepers,[242] who explains organic evolution by "laws of growth, ... uncontrolled by any process of selection." Dr. Cunningham likewise, in the preface to his translation of Eimer's work, gives his reasons for adopting Neolamarckian views, concluding that "the theory of selection can never get over the difficulty of the origin of entirely new characters;" that "selection, whether natural or artificial, could not be the essential cause of the evolution of organisms." In an article on "The New Darwinism" (_Westminster Review_, July, 1891) he claims that Weismann's theory of heredity does not explain the origin of horns, venomous teeth, feathers, wings of insects, or mammary glands, phosphorescent organs, etc., which have arisen on animals whose ancestors never had anything similar. Discussing the origin of whales and other aquatic mammals, W. Kükenthal suggests that the modifications are partially attributable to mechanical principles. (_Annals and Mag. Nat. Hist._, February, 1891.) From his studies on the variation of butterflies, Karl Jordan[243] proposes the term "mechanical selection" to account for them, but he points out that this factor can only work on variations produced by other factors. Certain cases, as the similar variation in the same locality of two species of different families, but with the same wing pattern, tell in favor of the direct action of the local surroundings on the markings of the wings. In the same direction are the essays of Schroeder[244] on the markings of caterpillars, which he ascribes to the colors of the surroundings; of Fischer[245] on the transmutations of butterflies as the result of changes of temperature, and also Dormeister's[246] earlier paper. Steinach[247] attributes the color of the lower vertebrates to the direct influence of the light on the pigment cells, as does Biedermann.[248] In his address on evolution and the factors of evolution, Professor A. Giard[249] has given due credit to Lamarck as "the creator of transformism," and to the position to be assigned to natural selection as a secondary factor. He quotes at length Lamarck's views published in 1806. After enumerating the primary factors of organic evolution, he places natural selection among his secondary factors, such as heredity, segregation, amixia, etc. On the other hand, he states that Lamarck was not happy in the choice of the examples which he gave to explain the action of habits and use of parts. "Je ne rappellerai par l'histoire tant de fois critique du cou de la giraffe et des cornes de l'escargot." Another important factor in the evolution of the metazoa or many-celled animals, from the sponges and polyps upward from the one-celled forms or protozoa, is the principle of animal aggregation or colonization advanced by Professor Perrier. As civilization and progressive intelligence in mankind arose from the aggregation of men into tribes or peoples which lived a sedentary life, so the agricultural, building, and other arts forthwith sprang up; and as the social insects owe their higher degree of intelligence to their colonial mode of life, so as soon as unicellular organisms began to become fixed, and form aggregates, the sponge and polyp types of organization resulted, this leading to the gastræa, or ancestral form from which all the higher phyla may have originated. M. Perrier appears to fully accept Lamarck's views, including his speculations as to wants, and use and disuse. He, however, refuses to accept Lamarck's extreme view as to the origin through effort of entirely new organs. As he says: "Unfortunately, if Lamarck succeeded in explaining in a plausible way the modification of organs already existing, their adaptation to different uses, or even their disappearance from disuse, in regard to the appearance of new organs he made hypotheses so venturesome that they led to the momentary forgetfulness of his other forceful conceptions."[250] The popular idea of Lamarckism, and which from the first has been prejudicial to his views, is that an animal may acquire an organ by simply wishing for or desiring it, or, as his French critics put it, "Un animal finit toujours par posséder un organe quand il le veut." "Such," says Perrier,[251] "is not the idea of Lamarck, who simply attributes the transformations of species to the stimulating action of external conditions, construing it under the expression of wants (_besoins_), and explaining by that word what we now call _adaptations_. Thus the long neck of the giraffe results from the fact that the animal inhabits a country where the foliage is situated at the tops of high trees; the long legs of the wading birds have originated from the fact that these birds are obliged to seek their food in the water without wetting themselves," etc. (See p. 350.) "Many cases," says Perrier, "may be added to-day to those which Lamarck has cited to support his first law [pp. 303, 346]; the only point which is open to discussion is the extent of the changes which an organ may undergo, through the use it is put to by the animal. It is a simple question of measurement. The possibility of the creation of an organ in consequence of external stimuli is itself a matter which deserves to be studied, and which we have no right to reject without investigation, without observations, or to treat as a ridiculous dream; Lamarck would doubtless have made it more readily accepted, if he had not thought it well to pass over the intermediate steps by means of wants. It is incontestable that by lack of exercise organs atrophy and disappear." Finally, says Perrier: "Without doubt the real mechanism of the improvement (_perfectionnement_) of organisms has escaped him [Lamarck], but neither has Darwin explained it. The law of natural selection is not the indication of a process of transformation of animals; it is the expression of the total results. It states these results without showing us how they have been brought about. We indeed see that it tends to the preservation of the most perfect organisms; but Darwin does not show us how the organisms themselves originated. This is a void which we have only during these later years tried to fill" (p. 90). Dr. J. A. Jeffries, author of an essay "On the Epidermal System of Birds," in a later paper[252] thus frankly expresses his views as to the relations of natural selection to the Lamarckian factors. Referring to Darwin's case of the leg bones of domestic ducks compared with those of wild ducks, and the atrophy of disused organs, he adds: "In this case, as with most of Lamarck's laws, Darwin has taken them to himself wherever natural selection, sexual selection, and the like have fallen to the ground. "Darwin's natural selection does not depend, as is popularly supposed, on direct proof, but is adduced as an hypothesis which gains its strength from being compatible with so many facts of correlation between an organism and its surroundings. Yet the same writer who considers natural selection proved will call for positive experimental proof of Lamarck's theory, and refuse to accept its general compatibility with the facts as support. Almost any case where natural selection is held to act by virtue of advantage gained by use of a part is equally compatible with Lamarck's theory of use and development. The wings of birds of great power of flight, the relations of insects to flowers, the claws of beasts of prey, are all cases in point." Professor J. A. Thomson's useful _Synthetic Summary of the Influence of the Environment upon the Organism_ (1887) takes for its text Spencer's aphorism, that the direct action of the medium was the primordial factor of organic evolution. Professor Geddes relies on the changes in the soil and climate to account for the origin of spines in plants. The botanist Sachs, in his _Physiology of Plants_ (1887), remarks: "A far greater portion of the phenomena of life are [is] called forth by external influences than one formerly ventured to assume." Certain botanists are now strong in the belief that the species of plants have originated through the direct influence of the environment. Of these the most outspoken is the Rev. Professor G. Henslow. His view is that self-adaptation, by response to the definite action of changed conditions of life, is the true origin of species. In 1894[253] he insisted, "_in the strictest sense of the term_, that natural selection is not wanted as an 'aid' or a 'means' in originating species." In a later paper[254] he reasserts that all variations are definite, that there are no indefinite variations, and that natural selection "can take no part in the origination of varieties." He quotes with approval the conclusion of Mr. Herbert Spencer in 1852, published "seven years before Darwin and Dr. Wallace superadded natural selection as an aid in the origin of species. He saw no necessity for anything beyond the natural power of change with adaptation; and I venture now to add my own testimony, based upon upwards of a quarter of a century's observations and experiments, which have convinced me that Mr. Spencer was right and Darwin was wrong. His words are as follows: 'The supporters of the development hypothesis can show ... that any existing species, animal or vegetable, when placed under conditions different from its previous ones, immediately begins to undergo certain changes of structure fitting it for the new conditions; ... that in the successive generations these changes continue until ultimately the new conditions become the natural ones.... They can show that throughout all organic nature there is at work a modifying influence of the kind they assign as the causes of specific differences; an influence which, though slow in its action, does in time, if the circumstances demand it, produce marked changes.'"[255] Mr. Henslow adduces observations and experiments by Buckman, Bailey, Lesage, Lothelier, Costantin, Bonnier, and others, all demonstrating that the environment acts directly on the plant. Henslow also suggests that endogens have originated from exogenous plants through self-adaptation to an aquatic habit,[256] which is in line with our idea that certain classes of animals have diverged from the more primitive ones by change of habit, although this has led to the development of new class-characteristics by use and disuse, phenomena which naturally do not operate in plants, owing to their fixed conditions. Other botanists--French, German, and English--have also been led to believe in the direct influence of the _milieu_, or environment. Such are Viet,[257] and Scott Elliot,[258] who attributes the growth of bulbs to the "direct influence of the climate." In a recent work Costantin[259] shares the belief emphatically held by some German botanists in the direct influence of the environment not only as modifying the form, but also as impressing, without the aid of natural selection, that form on the species or part of its inherited stock; and one chapter is devoted to an attempt to establish the thesis that acquired characters are inherited. In his essay "On Dynamic Influences in Evolution" W. H. Dall[260] holds the view that-- "The environment stands in a relation to the individual such as the hammer and anvil bear to the blacksmith's hot iron. The organism suffers during its entire existence a continuous series of mechanical impacts, none the less real because invisible, or disguised by the fact that some of them are precipitated by voluntary effort of the individual itself.... It is probable that since the initiation of life upon the planet no two organisms have ever been subjected to exactly the same dynamic influences during their development.... The reactions of the organism against the physical forces and mechanical properties of its environment are abundantly sufficient, if we are granted a single organism, with a tendency to grow, to begin with; time for the operation of the forces; and the principle of the survival of the fittest." In his paper on the hinge of Pelecypod molluscs and its development, he has pointed out a number of the particular ways in which the dynamics of the environment may act on the characters of the hinge and shell of bivalve molluscs. He has also shown that the initiation and development of the columellar plaits in Voluta, Mitra, and other gasteropod molluscs "are the necessary mechanical result of certain comparatively simple physical conditions; and that the variations and peculiarities connected with these plaits perfectly harmonize with the results which follow within organic material subjected to analogous stresses." In the same line of study is Dr. R. T. Jackson's[261] work on the mechanical origin of characters in the lamellibranch molluscs. "The bivalve nature of the shell doubtless arose," he says, "from the splitting on the median line of a primitive univalvular ancestor;" and he adds: "A parallel case is seen in the development of a bivalve shell in ancient crustaceans;" in both types of shells "the form is induced by the mechanical conditions of the case." The adductor muscles of bivalve molluscs and crustaceans are, he shows plainly, the necessary consequence of the bivalvular condition. In his theory as to the origin of the siphon of the clam (_Mya arenaria_), he explains it in a manner identical with Lamarck's explanations of the origin of the wading and swimming birds, etc., even to the use of the words "effort" and "habit." "In _Mya arenaria_ we find a highly elongated siphon. In the young the siphon hardly extends beyond the borders of the valves, and then the animal lives at or close to the surface. In progressive growth, as the animal burrows deeper, the siphon elongates, until it attains a length many times the total length of the valves. "The ontogeny of the individual and the paleontology of the family both show that Mya came from a form with a very abbreviated siphon, and it seems evident that the long siphon of this genus was brought about by the effort to reach the surface induced by the habit of deep burial." "The tendency to equalize the form of growth in a horizontal plane, or the geomalic tendency of Professor Hyatt,[262] is seen markedly in pelecypods. In forms which crawl on the free borders of the valves, the right and left growth in relation to the perpendicular is obvious, and agrees with the right and left sides of the animal. In Pecten the animal at rest lies on the right valve, and swims or flies with the right valve lowermost. Here equalization to the right and left of the perpendicular line passing through the centre of gravity is very marked (especially in the Vola division of the group); but the induced right and left aspect corresponds to the dorsal and ventral sides of the animal, not the right and left sides, as in the former case. Lima, a near ally of Pecten, swims with the edges of the valves perpendicular. In this case the geomalic growth corresponds to the right and left sides of the animal. "The oyster has a deep or spoon-shaped attached valve, and a flat or flatter free valve. This form, or a modification of it, we find to be characteristic of all pelecypods which are attached to a foreign object of support by the cementation of one valve. All are highly modified, and are strikingly different from the normal form seen in locomotive types of the group. The oyster may be taken as the type of the form adopted by attached pelecypods. The two valves are unequal, the attached valve being concave, the free valve flat; but they are not only unequal, they are often very dissimilar--as different as if they belonged to a distinct type in what would be considered typical forms. This is remarkable as a case of acquired and inherited characteristics finding very different expression in the two valves of a group belonging to a class typically equivalvular. The attached valve is the most highly modified, and the free is least modified, retaining more fully ancestral characters. Therefore, it is to the free young before fixation takes place and to the free, least-modified valve that we must turn in tracing genetic relations of attached groups. Another characteristic of attached pelecypods is camerated structure, which is most frequent and extensive in the thick attached valve. The form as above described is characteristic of the Ostreidæ, Hinnites, Spondylus, and Plicatula, Dimya, Pernostrea, Aetheria, and Mulleria; and Chama and its near allies. These various genera, though ostreiform in the adult, are equivalvular and of totally different form in the free young. The several types cited are from widely separated families of pelecypods, yet all, under the same given conditions, adopt a closely similar form, which is strong proof that common forces acting on all alike have induced the resulting form. What the forces are that have induced this form it is not easy to see from the study of this form alone; but the ostrean form is the base of a series, from the summit of which we get a clearer view." (_Amer. Nat._, pp. 18-20.) Here we see, plainly brought out by Jackson's researches, that the Lamarckian factors of change of environment and consequently of habit, effort, use and disuse, or mechanical strains resulting in the modifications of some, and even the appearance of new organs, as the adductor muscles, have originated new characters which are peculiar to the class, and thus a new class has been originated. The mollusca, indeed, show to an unusual extent the influence of a change in environment and of use and disuse in the formation of classes. Lang's treatment, in his _Text-book of Comparative Anatomy_ (1888), of the subjects of the musculature of worms and crustacea, and of the mechanism of the motion of the segmented body in the Arthropoda, is of much value in relation to the mechanical genesis of the body segments and limbs of the members of this type. Dr. B. Sharp has also discussed the same subject (_American Naturalist_, 1893, p. 89), also Graber in his works, while the present writer in his _Text-book of Entomology_ (1898) has attempted to treat of the mechanical origin of the segments of insects, and of the limbs and their jointed structure, along the lines laid down by Herbert Spencer, Lang, Sharp, and Graber. W. Roux[263] has inquired how natural selection could have determined the special orientation of the sheets of spongy tissue of bone. He contends that the selection of accidental variation could not originate species, because such variations are isolated, and because, to constitute a real advantage, they should rest on several characters taken together. His example is the transformation of aquatic into terrestrial animals. G. Pfeffer[264] opposes the efficacy of natural selection, as do C. Emery[265] and O. Hertwig. The essence of Hertwig's _The Biological Problem of To-day_ (1894) is that "in obedience to different external influences the same rudiments may give rise to different adult structures" (p. 128). Delage, in his _Théories sur l'Hérédité_, summarizes under seven heads the objections of these distinguished biologists. Species arise, he says, from general variations, due to change in the conditions of life, such as food, climate, use and disuse, very rarely individual variations, such as sports or aberrations, which are more or less the result of disease. Mention should also be made of the essays and works of H. Driesch,[266] De Varigny,[267] Danilewsky,[268] Verworn,[269] Davenport,[270] Gadow,[271] and others. In his address on "Neodarwinism and Neolamarckism," Mr. Lester F. Ward, the palæobotanist, says: "I shall be obliged to confine myself almost exclusively to the one great mind, who far more than all others combined paved the way for the new science of biology to be founded by Darwin, namely, Lamarck." After showing that Lamarck established the functional, or what we would call the dynamic factors, he goes on to say that "Lamarck, although he clearly grasped the law of competition, or the struggle for existence, the law of adaptation, or the correspondence of the organism to the changing environment, the transmutation of species, and the genealogical descent of all organic beings, the more complex from the more simple; he nevertheless failed to conceive the selective principle as formulated by Darwin and Wallace, which so admirably complemented these great laws."[272] As is well known, Huxley was, if we understand his expressions aright, not fully convinced of the entire adequacy of natural selection. "There is no fault to be found with Mr. Darwin's method, then; but it is another question whether he has fulfilled all the conditions imposed by that method. Is it satisfactorily proved, in fact, that species may be originated by selection? that there is such a thing as natural selection? that none of the phenomena exhibited by species are inconsistent with the origin of species in this way? * * * * * "After much consideration, with assuredly no bias against Mr. Darwin's views, it is our clear conviction that, as the evidence stands, it is not absolutely proven that a group of animals, having all the characters exhibited by species in nature, has ever been originated by selection, whether artificial or natural. Groups having the morphological character of species, distinct and permanent races, in fact, have been so produced over and over again; but there is no positive evidence, at present, that any group of animals has, by variation and selective breeding, given rise to another group which was even in the least degree infertile with the first. Mr. Darwin is perfectly aware of this weak point, and brings forward a multitude of ingenious and important arguments to diminish the force of the objection."[273] We have cited the foregoing conclusions and opinions of upwards of forty working biologists, many of whom were brought up, so to speak, in the Darwinian faith, to show that the pendulum of evolutionary thought is swinging away from the narrow and restricted conception of natural selection, pure and simple, as the sole or most important factor, and returning in the direction of Lamarckism. We may venture to say of Lamarck what Huxley once said of Descartes, that he expressed "the thoughts which will be everybody's two or three centuries after" him. Only the change of belief, due to the rapid accumulation of observed facts, has come in a period shorter than "two or three centuries;" for, at the end of the very century in which Lamarck, whatever his crudities, vagueness, and lack of observations and experiments, published his views, wherein are laid the foundations on which natural selection rests, the consensus of opinion as to the direct and indirect influence of the environment, and the inadequacy of natural selection as an initial factor, was becoming stronger and deeper-rooted each year. We must never forget or underestimate, however, the inestimable value of the services rendered by Darwin, who by his patience, industry, and rare genius for observation and experiment, and his powers of lucid exposition, convinced the world of the truth of evolution, with the result that it has transformed the philosophy of our day. We are all of us evolutionists, though we may differ as to the nature of the efficient causes. FOOTNOTES: [204] Vol. ii., p. 167, 1871. [205] Vol. ii., p. 195. [206] Vol. i., § 166, p. 456. [207] _The Factors of Organic Evolution_, 1895, p. 460. [208] _Schöpfungegeschichte_, 1868. _The History of Creation_, New York, ii., p. 355. [209] Alcide d'Orbigny, _Paléontologie française_, Paris, 1840-59. [210] Abstract in Proceedings of the Boston Society of Natural History, xvii., December 16, 1874. [211] _Zeitschr. der deutsch. geol. Gesellschaft_, 1875. [212] _Palæontologica Indica_. Jurassic Fauna of Kutch. I. Cephalopoda, pp. 242-243. (See Hyatt's _Genesis of the Arietidæ_, pp. 27, 42.) [213] "Genera of Fossil Cephalopods," Proc. Bost. Soc. Nat. Hist., xxii., April 4, 1883, p. 265. [214] "Revision of the North American Poriferæ." Memoirs Bost. Soc. Nat. Hist., ii., part iv., 1877. [215] _Three Cruises of the "Blake,"_ 1888, ii., p. 158. [216] The earliest paper in which he adopted the Lamarckian doctrines of use and effort was his "Methods of Creation of Organic Types" (1871). In this paper Cope remarks that he "has never read Lamarck in French, nor seen a statement of his theory in English, except the very slight notices in the _Origin of Species_ and _Chambers' Encyclopædia_, the latter subsequent to the first reading of this paper." It is interesting to see how thoroughly Lamarckian Cope was in his views on the descent theory. [217] Proceedings of the American Association for the Advancement of Science, Troy meeting, 1870. Printed in August, 1871. [218] _American Naturalist_, v., December, 1871, p. 750. See also pp. 751, 759, 760. [219] Printed in advance, being chapter xiii. of _Our Common Insects_, Salem, 1873, pp. 172, 174, 179, 180, 181, 185. [220] "A New Cave Fauna in Utah." _Bulletin of the United States Geological Survey_, iii., April 9, 1877, p. 167. [221] Memoirs of the National Academy of Sciences, iv., 1888, pp. 156: 27 plates. See also _American Naturalist_, Sept., 1888, xxii., p. 808, and Sept., 1894, xxviii., p. 333. [222] Carl H. Eigenmann, in his elaborate memoir, _The Eyes of the Blind Vertebrates of North America (Archiv für Entwickelungsmechanik der Organismen_, 1899, viii.), concludes that the Lamarckian view, that through disuse and the transmission by heredity of the characters thus inherited the eyes of blind fishes are diminished, "is the only view so far examined that does not on the face of it present serious objections" (pp. 605-609). [223] "Hints on the Evolution of the Bristles, Spines, and Tubercles of Certain Caterpillars, etc." Proceedings Boston Society of Natural History, xxiv., 1890, pp. 493-560; 2 plates. [224] E. J. Marey: "Le Transformisme et la Physiologie Expérimentale, Cours du Collège de France," _Revue Scientifique_, 2^me série, iv., p. 818. (Function makes the organ, especially in the osseous and muscular systems.) See also A. Dohrn: _Der Ursprung der Wirbelthiere und das Princip des Functionswechsels_, Leipzig, 1875. See also Lamarck's opinion, p. 295. [225] "On the Inheritance of Acquired Characters in Animals with a Complete Metamorphosis." Proceedings Amer. Acad. Arts and Sciences, Boston, xxix. (N. S., xxi.). 1894, pp. 331-370; also monograph of "Bombycine Moths," Memoirs Nat. Acad. Sciences, vii., 1895, p. 33. [226] In 1885, in the Introduction to the _Standard Natural History_, we proposed the term Neolamarckianism, or Lamarckism in its modern form, to designate the series of factors of organic evolution, and we take the liberty to quote the passage in which the word first occurs. We may add that the briefer form, Neolamarckism, is the more preferable. "In the United States a number of naturalists have advocated what may be called Neo-Lamarckian views of evolution, especially the conception that in some cases rapid evolution may occur. The present writer, contrary to pure Darwinians, believes that many species, but more especially types of genera and families, have been produced by changes in the environment acting often with more or less rapidity on the organism, resulting at times in a new genus, or even a family type. Natural selection, acting through thousands, and sometimes millions, of generations of animals and plants, often operates too slowly; there are gaps which have been, so to speak, intentionally left by Nature. Moreover, natural selection was, as used by some writers, more an idea than a _vera causa_. Natural selection also begins with the assumption of a tendency to variation, and presupposes a world already tenanted by vast numbers of animals among which a struggle for existence was going on, and the few were victorious over the many. But the entire inadequacy of Darwinism to account for the primitive origin of life forms, for the original diversity in the different branches of the tree of life forms, the interdependence of the creation of ancient faunas and floras on geological revolutions, and consequent sudden changes in the environment of organisms, has convinced us that Darwinism is but one of a number of factors of a true evolution theory; that it comes in play only as the last term of a series of evolutionary agencies or causes; and that it rather accounts, as first suggested by the Duke of Argyll, for the _preservation_ of forms than for their origination. We may, in fact, compare Darwinism to the apex of a pyramid, the larger mass of the pyramid representing the complex of theories necessary to account for the world of life as it has been and now is. In other words, we believe in a modified and greatly extended Lamarckianism, or what may be called Neo-Lamarckianism." [227] _Studies in the Theory of Descent_. By Dr. August Weismann. Translated and edited, with notes, by Raphael Meldola. London, 1882. 2 vols. [228] "The Influence of Physical Conditions in the Genesis of Species," _Radical Review_, i., May, 1877. See also J. A. Allen in Bull. Mus. Comp. Zoöl. ii., 1871; also R. Ridgway, _American Journal of Science_, December, 1872, January, 1873. [229] Annual Report of the United States Geological and Geographical Survey Territories, 1873. Pp. 543-560. See also the author's monograph of Geometrid Moths or Phalænidæ of the United States, 1876, pp. 584-589, and monograph of Bombycine Moths (Notodontidæ), p. 50. [230] Proceedings Academy of Natural Science, Philadelphia (1877), p. 318. [231] Proceedings of the American Philosophical Society (1889), p. 546. [232] Transactions American Philosophical Society, xvi. (1890), and later papers. [233] _American Journal of Morphology_ (1891), pp. 395, 398. [234] "Über die Darwinische Theorie in Besug auf die geographische Verbreitung der Organismen." Sitzenb. der Akad. München, 1868. Translated by J. L. Laird under the title, _The Darwinian Theory and the Law of the Migration of Organisms_. London, 1873. Also _Ueber den Einfluss der geographischen Isolirung und Colonierbildung auf die morphologischen Veränderungen der Organismen_. München, 1870. [235] _Linnæan Society's Journal_: Zoölogy, xi., 1872. [236] _Linnæan Society's Journal_: Zoölogy, xx., 1887, pp. 189-274, 496-505: also _Nature_, July 18, 1872. [237] _Evolution without Natural Selection; or, The Segregation of Species without the aid of the Darwinian Hypothesis_, London (1885), pp. 1-80. [238] _Revue Scientifique_, xix. (1877). p. 669. Quoted by Giard in _Rev. Sci._, 1889, p. 646. [239] _Animal Life as Affected by the Natural Conditions of Existence._ By Karl Semper. The International Scientific Series. New York, 1881. [240] _Organic Evolution as the Result of the Inheritance of Acquired Characters, according to the Laws of Organic Growth._ Translated by J. T. Cunningham, 1890. [241] _On Orthogenesis and the Impotence of Natural Selection in Species Formation._ Chicago, 1898. [242] _Die Farbenevolution bei den Pieriden_. Leiden, 1898. [243] "On Mechanical Selection and Other Problems." _Novitates Zoologicæ_, iii. Tring, 1896. [244] _Entwicklung der Raupenzeichnung und Abhängigkeit der letzeren von der Farbe der Umgebung_, 1894. [245] _Transmutation der Schmetterlinge infolge Temperatur-veränderungen_, 1895. [246] _Ueber den Einfluss der Temperatur bei der Erzeugung der Schmetterlings-varietäten_, 1880. [247] _Ueber Farbenwechsel bei niederen Wirbelthieren, bedingt durch directe Wirkung des Lichts auf die Pigmentzellen._ _Centralblatt für Physiologie_, 1891, v., p. 326. [248] _Ueber den Farbenwechsel der Frösche._ _Pflüger's Archiv für Physiologie_, 1892, li., p. 455. [249] _Leçon d'Ouverture du Cours de l'Évolution des Êtres organisés._ Paris, 1888, and "Les Facteurs de l'Évolution," _Revue Scientifique_, November 23, 1889. [250] _Revue Encyclopédique_, 1897. p. 325. Yet we have an example of the appearance of a new organ in the case of the duckbill, in which the horny plates take the place of the teeth which Poulton has discovered in the embryo. Other cases are the adductor muscles of shelled crustacea. (See p. 418.) [251] _La Philosophie Zoologique avant Darwin_. Paris, 1884, p. 76. [252] "Lamarckism and Darwinism." Proceedings Boston Society Natural History, xxv., 1890, pp. 42-49. [253] "The Origin of Species without the Aid of Natural Selection," _Natural Science_, Oct., 1894. Also, "The Origin of Plant Structures." [254] "Does Natural Selection play any Part in the Origin of Species among Plants?" _Natural Science_, Sept., 1897. [255] "Essay on the Development Hypothesis," 1852, London _Times_. [256] "A Theoretical Origin of Endogens from Exogens through Self-Adaptation to an Aquatic Habit," _Linnean Society Journal_: Botany, 1892, _l. c._, xxix., pp. 485-528. A case analogous to kinetogenesis in animals is his statement based on mathematical calculations by Mr. Hiern, "that the best form of the margin of floating leaves for resisting the strains due to running water is circular, or at least the several portions of the margin would be circular arcs" (p. 517). [257] "De l'Influence du Milieu sur la Structure anatomique des Végétaux," _Ann. Sci. Nat. Bot._, ser. 6, xii., 1881, p. 167. [258] "Notes on the Regional Distribution of the Cape Flora," _Transactions_ Botanical Society, Edinburgh. 1891, p. 241. [259] _Les Végétaux et les Milieux cosmiques_, Paris, 1898, pp. 292. [260] Proceedings Biological Society of Washington, 1890. [261] "Phylogeny of the Pelecypoda," Memoirs Boston Society Natural History, iv., 1890, pp. 277-400. Also, _American Naturalist_, 1891, xxv., pp. 11-21. [262] "Transformations of Planorbis at Steinheim, with Remarks on the Effects of Gravity upon the Forms of Shells and Animals," Proceedings A. A. A. S., xxix., 1880. [263] _Der Kampf der Theile im Organismus_. Leipzig, 1881. Also _Gesammelte Abhandlungen über Entwickelungsmechanik der Organismen_. Leipzig, 1895. [264] _Die Unwandlung der Arten ein Vorgang functioneller Selbsgestaltung_. Leipzig, 1894. [265] _Gedanken zur Descendenz- und Vererbungstheorie; Biol. Centralblatt_, xiii., 1893, 397-420. [266] _Entwickelungmecanische Studien_, 1892-93. [267] _Experimental Evolution_, 1892; also, "Recherches sur le Nanisme experimental," _Journ. Anat. et Phys._, 1894. [268] "Ueber die organsplastischen Kräfte der Organismen," _Arbeit. nat. Ges._, Petersburg, xvi., 1885; Protok, 79-82. [269] _General Physiology_, 1899. [270] _Experimental Morphology_, 1897-99. 2 vols. [271] "Modifications of Certain Organs which seem to be Illustrations of the Inheritance of Acquired Characters in Mammals and Birds." _Zool. Jahrb. Syst. Abth._, 1890, iv., pp. 629-646; also, _The Lost Link_, by E. Haeckel, with notes, etc., by H. Gadow, 1899. [272] Proceedings Biological Society of Washington, vi., 1892, pp. 13, 19. [273] _Lay Sermons, Addresses, and Reviews_, 1870, p. 323. A BIBLIOGRAPHY OF THE WRITINGS OF J. B. DE LAMARCK[274] 1778-1828 1778 Flore française ou description succinte de toutes les plantes qui croissent naturellement en France, disposées selon une nouvelle méthode d'analyse et à laquelle on a joint la citation de leurs vertus les moins équivoques en médecine et de leur utilité dans les arts. Paris (Impr. Nationale), 1778. 8vo, 3 vol. Vol. I. Ext. du Rapport fait par MM. Duhamet et Guettard de cet ouvrage. pp. 1-4. Discours préliminaire. pp. i-cxix. Principes élémentaires de Botanique. pp. 1-223. Méthode analytique.--Plantes cryptogames. pp. 1-132, viii, pl. Vol. II. Méthode analytique.--Plantes adultes, ou dont les fleurs sont dans un état de développement parfait. pp. iv., 684. Vol. III. Méthode analytique. pp. 654, x. _Idem._ 2e édit. Paris, 1793. (1805-15) Flore française ou description succinte de toutes les plantes qui croissent naturellement en France, disposées selon une nouvelle méthode d'analyse, et précédées par un exposé des principes élémentaires de la Botanique. (En collaboration avec A. P. de Candolle). Édition III. Paris (Agasse), 1805. 4 vol., 8vo. Vol. I. Lettre de M. de Candolle à M. Lamarck. pp. xv. Discours préliminaire. (Réimpression de la 1re édit.) pp. 1-60. Principes élémentaires de Botanique, pp. 61-224. Méthode analytique: {analyse des genres. pp. 1-76. {analyse des espèces. pp. 77-388, 10 pl. Vol. II. Explication de la Carte botanique de France, pp. i-xii. Plantes acotylédonées. pp. 1-600. Carte coloriée. Vol. III. Monocotylédonées phanérogames. pp. 731. Vol. IV. " " pp. 944. Même édition, augmentée du tome 5 et tome 6, contenant 1300 espèces non décrites dans les cinq premiers volumes. Paris (Desray), 1815. 8vo, pp. 622. Lettre de M. A. P. de Candolle à M. Lamarck, pp. 10. 1783 Dictionnaire botanique.--(En Encyclopédie méthodique. Paris, in 4to.) I, 1783; II, 1786; pour le IIIe volume, 1789, Lamarck a été aidé par Desrousseaux. Le IVe, 1795, est de Desrousseaux, Poiret et Savigny. Les derniers: V, 1804; VI, 1804; VII, 1806; et VIII, 1808, sont de Poiret. Lamarck et Poiret. Encyclopédie méthod.: Botanique. 8 vols. et suppl. 1 à 3, avec 900 pl. 1784 Mémoire sur un nouveau genre de plante nommé Brucea, et sur le faux Brésillet d'Amérique. Mém. Acad. des Sci. 21 janvier 1784. pp. 342-347. 1785 Mémoire sur les classes les plus convenables à établir parmi les végétaux et sur l'analogie de leur nombre avec celles déterminées dans le règne animal, ayant égard de part et d'autre à la perfection graduée des organes. (De la classification des végétaux.) Mém. Acad. des Sci. 1785. pp. 437-453. 1788 Mémoire sur le genre du Muscadier, Myristica. Mém. Acad. des Sci. 1788. pp. 148-168, pl. v.-ix. 1790 Mémoire sur les cabinets d'histoire naturelle, et particulièrement sur celui du Jardin des Plantes; contenant l'exposition du régime et de l'ordre qui conviennent à cet établissement, pour qu'il soit vraiment utile. (No imprint.) 4to, pp. 15. Considérations en faveur du Chevalier de la Marck, ancien officier au Régiment de Beaujolais, de l'Académie Royale des Sciences; Botaniste du Roi, attaché au Cabinet d'Histoire Naturelle. [Paris] 1790. 8vo, pp. 7. 1791 Instruction aux voyageurs autour du monde, sur les observations les plus essentielles à faire en botanique. Soc. Philom. (Bull.) Paris, 1791, pp. 8. Illustrations des genres, ou exposition des caractères de tous les genres de plantes établis par les botanistes (Encyclopédie méthodique): I, 1791; II, 1793; III, 1800, avec 900 planches. (Le supplément, qui constitue le tome IV, 1823, est de Poiret.) Extrait de la flore française. Paris, 1792. 1 vol. in-8vo. Tableau encyclopédique et méthodique des trois règnes de la nature. Botanique continuée par J. L. M. Poiret. Paris (Panckoucke), 1791-1823. Text, 3 v.; Pls., 4 v. (Encyclopédie méthodique.) 4to. Tableau encyclopédique et méthodique des trois règnes de la nature. Mollusques testacés (et polypes divers). Paris (Panckoucke) [etc.], 1791-1816. Text (3), 180 pp. Pls. 2 v. (Encyclopédie méthodique.) 4to. _Idem._ Continuator Bruguière, Jean Guillaume. Histoire naturelle des vers. Par Bruguière [et J. B. P. A. de Lamarck; continuée par G. P. Deshayes]. Paris (Panckoucke) [etc.], 1792-1832, 3 v. (Encyclopédie méthodique.) 4to. 1792 Journal d'Histoire naturelle, rédigé par MM. Lamarck, Bruguière, Olivier, Haüy et Pelletier. Tomes I, II. Pl. 1-24, 25-40. Paris (Impr. du Cercle social), 1792. In-8vo, 2 vol. Le même, sous le titre: Choix de mémoires sur divers objets d'histoire naturelle, par Lamarck; formant les collections du Journal d'Hist. nat. 3 vol. in-8vo, tirés de format in-4to, dont le 3me contient 42 pl. Paris (Imprim. du Cercle social), 1792. _Nota._--Tous les exemplaires de cet ouvrage que l'on rencontre sont incomplets. Un exemplaire de format in-8vo, provenant de la Bibliothèque Cuvier (et qui se trouve à la Bibliothèque du Muséum), contient les pages 320 à 360; 8 pages copiées à la main terminent le volume, dont on connaît complet un seul exemplaire. Sur l'histoire naturelle en général. Sur la nature des articles de ce journal qui concernent la Botanique. Philosophie botanique. L'auteur propose dans cet article un nouveau genre de plante: le Genre Rothia (Rothia Carolinensis, p. 17, pl. 1). Journ. d'Hist. nat. I, 1792. pp. 1-19. (Ce recueil porte aussi le titre suivant: Choix de mémoires sur divers objets d'Histoire naturelle, par MM. Lamarck, Bruguière, Olivier, Haüy et Pelletier.) Sur le Calodendron (Calodendron Capense), pp. 56, pl. 3. Journ. d'Hist. nat. I, 1792. pp. 56-62. Philosophie botanique. Journ. d'Hist. nat. I, 1792. pp. 81-92. (Dans cet article l'auteur donne la description de: Mimosa obliqua. pp. 89, pl. 5.) Sur les travaux de Linné. Journ. d'Hist. nat. I, 1792. pp. 136-144. (L'auteur conclut que tout ce que fit Linnæus pour la botanique, il le fit aussi pour la zoologie; et ne donna pas moins de preuves de son génie en traitant le règne minéral, quoique dans cette partie de l'histoire naturelle il fut moins heureux en principes et en convenances dans les rapprochements et les déterminations, que dans les deux autres règnes.) Sur une nouvelle espèce de Vantane. Ventanea parviflora. p. 145, pl. 7. Journ. d'Hist. nat. I, 1792. pp. 144-148. Exposition d'un nouveau genre de plante nommé Drapètes. Drapetes muscosus et seq. p. 159, pl. 10, fig. 1. Journ. d'Hist. nat. I, 1792. pp. 1-190. Sur le Phyllachne. Phyllachne uliginosa. p. 192, pl. 10, fig. 2. Journ. d'Hist. nat. I, 1792. pp. 190-192. Sur l'Hyoseris Virginica. p. 222, pl. 12. Journ. d'Hist. nat. I, 1792. pp. 222-224. Sur le genre des Acacies; et particulièrement sur l'Acacie hétérophille. Mimosa heterophylla. p. 291, pl. 15. Journ. d'Hist. nat. I, 1792. pp. 288-292. Sur les Systèmes et les Méthodes de Botanique et sur l'Analyse. Journ. d'Hist. nat. I, 1792. pp. 300-307. Sur une nouvelle espèce de Grassette. Pinguicula campanulata, p. 336, pl. 18, fig. I. Journ. d'Hist. nat. I, 1792. pp. 334-338. Sur l'étude des rapports naturels. Journ. d'Hist. nat. I, 1792. pp. 361-371. Sur les relations dans leur port ou leur aspect, que les plantes de certaines contrées ont entre elles, et sur une nouvelle espèce d'Hydrophylle. Hydrophyllum Magellanicum. p. 373, pl. 19. Journ. d'Hist. nat. I. 1792. pp. 371-376. Notice sur quelques plantes rares ou nouvelles, observées dans l'Amérique Septentrionale par M. A. Michaux; adressée à la Société d'Histoire naturelle de Paris par l'auteur; et rédigée avec des observations. Canna flava--Pinguicula lutea--Ilex Americana--Ilex æstivalis--Ipomæa rubra--Mussænda frondosa--Kalmia hirsuta--Andromeda mariana--A. formosissima. Journ. d'Hist. nat I, 1792. pp. 409-419. Sur une nouvelle espèce de Loranthe. Loranthus cucullaris. p. 444, pl. 23. Journ. d'Hist. nat. I, 1792. pp. 444-448. Sur le nouveau genre Polycarpea. Polycarpæa Teneriffæ. p. 5, pl. 25. Journ. d'Hist. nat. II, 1792. pp. 3-8. Sur l'augmentation continuelle de nos connaissances à l'égard des espèces et sur une nouvelle espèce de Sauge. Salvia scabiosæfolia. p. 44, pl. 27. Journ. d'Hist. nat. II, 1792. pp. 41-47. Sur une nouvelle espèce de Pectis. Pectis pinnata. p. 150, pl. 31. Journ. d'Hist. nat. II, 1792. pp. 148-154. Sur le nouveau genre Sanvitalia. Sanvitalia procumbens. p. 178, pl. 35. Journ. d'Hist. nat. II, 1792. pp. 176-179. Sur l'augmentation remarquable des espèces dans beaucoup de genres qui n'en offraient depuis longtemps qu'une, et particulièrement sur une nouvelle espèce d'Hélénium. Helenium caniculatum. p. 213, pl. 35. Journ. d'Hist. nat. II, 1792. pp. 210-215. Observations sur les coquilles, et sur quelques-uns des genres qu'on a établis dans l'ordre des Vers testacés. Purpurea, Fusus, Murex, Terebra, etc. Journ. d'Hist. nat. II, 1792. pp. 269-280. Sur l'Administration forestière, et sur les qualités individuelles des bois indigènes, ou qui sont acclimatés en France; auxquels on a joint la description des bois exotiques, que nous fournit le commerce. Par _P. C. Varenne-Tenille_, Bourg (Philippon), 1792. 2 vol. 8vo. Journ. d'Hist. nat. II, 1792. pp. 299-301. Sur quatre espèces d'Hélices. Journ. d'Hist nat. II, 1792. pp. 347-353. Prodrome d'une nouvelle classification des coquilles, comprenant une rédaction appropriée des caractères génériques et l'établissement d'un grand nombre de genres nouveaux.--In Mém. Soc. Hist. nat. Paris, I, 1792. p. 63. Sur les ouvrages généraux en Histoire naturelle; et particulièrement sur l'édition du Systema Naturæ de Linnæus, que M. Gmelin vient de publier. Act. Soc. Hist. nat., Paris, I. 1re Part., 1792. pp. 81-85. 1794 Recherches sur les Causes des principaux Faits physiques, et particulièrement sur celles de la Combustion, de l'Elévation de l'eau dans l'état de vapeurs; de la Chaleur produite par le frottement des corps solides entre eux; de la Chaleur qui se rend sensible dans les décompositions subites, dans les effervescences et dans le corps de beaucoup d'animaux pendant la durée de leur vie; de la Causticité, de la Saveur et de l'Odeur de certains composés; de la Couleur des corps; de l'Origine des composés et de tous les minéraux; enfin, de l'Entretien de la vie des êtres organiques, de leur accroissement, de leur état de vigueur, de leur dépérissement et de leur mort. Avec une planche. Tomes 1, 2. Paris, seconde année de la république [1794]. 8vo. Mémoire sur les molécules essentiels des composés. Soc. philom. Rapp., 1792-98. pp. 56-57. Voyage de Pallas dans plusieurs provinces de l'empire de Russie et dans l'Asie septentrionale, traduit de l'allemand par Gauthier de la Peyronnerie. Nouvelle édition revue et enrichie de notes par Lamarck, Langlès et Billecoq. Paris, an II (1794). 8 vol. in-8vo, avec un atlas de 108 pl. folio. 1796 Voyage au Japon, par le cap de Bonne-Espérance, les îles de la Sonde, etc., par Thunberg, traduit, rédigé (sur la version anglaise), etc., par Langlès, et _revu, quant à l'histoire naturelle_, par Lamarck. Paris. 1796. 2 vol. in-4to (8vo, 4 vol.), av. fig. Réfutation de la théorie pneumatique et de la nouvelle théorie des chimistes modernes, etc. Paris, 1796. 1 vol. 8vo. 1797 Mémoires de physique et d'histoire naturelle, établis sur des bases de raisonnement indépendantes de toute théorie; avec l'explication de nouvelles considérations sur la cause générale des dissolutions, sur la matière du feu; sur la couleur des corps; sur la formation des composés; sur l'origine des minéraux; et sur l'organisation des corps vivants. Lus à la première classe de l'Institut national, dans ses séances ordinaires. Paris, an V (1797). 1 vol. 8vo. pp. 410. De l'influence de la lune sur l'atmosphère terrestre, etc. Bull. Soc. philom. I., 1797; pp. 116-118. Gilbert Annal. VI, 1800; pp. 204-223; et Nicholson's Journal, III, 1800; pp. 438-489. Mémoires de Physique et d'Histoire naturelle. Paris, 1797. 8vo. Biogr. un., Suppl. LXX. p. 22. 1798 De l'influence de la lune sur l'atmosphère terrestre. Journ. de Phys. XLVI, 1798; pp. 428-435. Gilbert Annal. VI, 1800; pp. 204-233. Tilloch, Philos. Mag. I, 1798; pp. 305-306. Paris, Soc. philom. (Bull.) II, 1797; pp. 116-118. Nicholson's Journ. III, 1800. pp. 488-489. Sensibility of Plants. (Translated from the Mémoires de Physique.) Tilloch, Philos. Mag. I, 1798. pp. 305-306. Mollusques testacés du tableau encyclopédique et méthodique des trois règnes de la nature, Paris, an VI (1798). 1 vol. in-4to de 299 pl., formant suite à l'Histoire des Vers de Bruguière (1792), continuée par Deshayes (1830), de l'Encyclopédie méthodique. 1799 Mémoire sur la matière du feu, considéré comme instrument chimique dans les analyses. 1º, De l'action du feu employé comme instrument chimique par la voie sèche; p. 134. 2º, De l'action du feu employé comme instrument chimique par la voie humide; p. 355. Journ. de Phys. XLVIII, 1799. pp. 345-361. Mémoire sur la matière du son. (Lu à l'Institut national, le 16 brumaire an VIII, et le 26 du même mois.) Journ. de Phys. XLIX, 1799. pp. 397-412. Sur les genres de la Sèche, du Calmar et du Poulpe, vulgairement nommés polypes de mer. (Lu à l'Institut national le 21 floréal an VI.) Soc. Hist. nat., Paris (Mém.), 1799. pp. 1-25, pl. 1, 2. Bibl. Paris, Soc. philom. (Bull.) I, Part. 2, 1799. pp. 129-131 (Extrait). Prodrome d'une nouvelle Classification des coquilles, comprenant une rédaction appropriée des caractères génériques, et l'établissement d'un grand nombre de genres nouveaux. (Lu à l'Institut national le 21 frimaire an VII.) Soc. Hist. nat., Paris (Mém.), 1789. pp. 63-91. Tableau systématique des Genres--126 g. Sur les fossiles et l'influence du mouvement des eaux, considérés comme indices du déplacement continuel du bassin des mers, et de son transport sur différents points de la surface du globe. (Lu à l'Institut national le 21 pluviôse an VII [1799].) Hydrogéologie, p. 172. Annuaire météorologique pour l'an VIII de la République française, etc. (Annonce.) Paris, Soc. philom. (Bull.) III, 1799. p. 56. 1800 Annuaire météorologique pour l'an VIII de la République. Paris, 1800. 1 vol. 16mo; 116 pp. Bibl., Gilbert Annal. VI, 1800. pp. 216-217. Mémoire sur le mode de rédiger et de noter les observations météorologiques, afin d'en obtenir des résultats utiles, et sur les considérations que l'on doit avoir en vue pour cet objet. Journ. de Phys. LI, 1800. pp. 419-426. Annuaire météorologique, contenant l'exposé des probabilités acquises par une longue suite d'observations sur l'état du ciel et sur les variations de l'atmosphère, etc. Paris, 1800-1810, 11 volumes, dont les 2 premiers in-18mo, les autres in-8vo. 1801 Système des Animaux sans Vertèbres ou Tableau général des classes, des ordres et des genres de ces animaux. Présentant leurs caractères essentiels et leur distribution d'après leurs rapports naturels, et de leur organisation; et suivant l'arrangement établi dans les galeries du Muséum d'Histoire naturelle parmi les dépouilles conservées. Précédé du discours d'Ouverture du Cours de Zoologie donné dans le Muséum d'Histoire naturelle l'an VIII de la République, le 21 floréal. Paris (Déterville), an IX (1801), VIII. pp. 452. Bibl., Paris, Soc. philom. (Bull.) III, 1802-4. pp. 7-8. Recherches sur la périodicité présumée des principales variations de l'atmosphère, et sur les moyens de s'assurer de son existence et de sa détermination. (Lues à l'Institut national de France, le 26 ventôse an IX.) Journ. de Phys. LII. 1801. pp. 296-316. Réfutation des résultats obtenus par le C. Cotte, dans ses recherches sur l'influence des constitutions lunaires, et imprimés dans le Journal de Physique, mois de fructidor an IX. p. 221. Journ. de Phys. LIII, 1801. pp. 277-281. Sur la distinction des tempêtes d'avec les orages, les ouragans, etc. Et sur le caractère du vent désastreux du 18 brumaire an IX (9 novembre 1800). (Lu à l'Institut national le 11 frimaire an IX.) Journ. de Phys. LII, floréal, 1801. pp. 377-380. 1802 Sur les variations de l'état du ciel dans les latitudes moyennes entre l'équateur et le pôle, et sur les principales causes qui y donnent lieu. Journ. de Phys. LVI. 1802. pp. 114-138. Recherches sur l'Organisation des Corps vivants et particulièrement sur son origine, sur la cause de ses développements et des progrès de sa composition, et sur celles qui, tendant continuellement à la détruire, dans chaque individu, amènent nécessairement sa mort. (Précédé du Discours d'Ouverture du Cours de Zoologie au Mus. nat. d'Hist. nat., an X de la République.) Paris (Maillard) [1802]. 1 vol. 8vo. pp. 216. Affinités chimiques, p. 73.--Anéantissement de la colonne vertébrale, p. 21.--Du coeur, p. 26.--De l'organe de la vue, p. 32.--Annélides, p. 24.--Arachnides, p. 27.--La Biologie, p. 186.--Création de la faculté de se reproduire, p. 114.--Crustacés, p. 25.--Dégradation de l'organisation d'une extrémité à l'autre de la chaîne des animaux, p. 7.--Échelle animale, p. 39.--Les éléments, p. 12.--Les espèces, pp. 141-149.--Exercice d'un organe, pp. 53, 56, 65, 125.--Les facultés, pp. 50, 56, 84, 125.--Fécondation, p. 95.--Fluide nerveux, pp. 114, 157, 166, 169.--Formation directe des premiers traits de l'organisation, pp. 68, 92, 94, 98.--Générations spontanées, pp. 46, 100, 115.--Habitudes des animaux, pp. 50, 125, 129.--Homme, p. 124.--Imitation, p. 130.--Influence du fluide nerveux sur les muscles, p. 169.--Insectes, p. 28.--Irritabilité, pp. 109, 179, 186.--Mammaux, p. 15.--Molécules intégrants des composés, p. 150.--Mollusques, p. 23.--Mouvement organique, pp. 7-9.--Multiplication des individus, pp. 117-120.--Nature animale, p. 8.--Nutrition, p. 8.--Oiseaux, p. 16.--Orgasme vital, pp. 79-83.--Organes des corps vivants, p. 111.--Organes de la pensée, p. 127.--Organisation, pp. 9, 98, 104, 134.--Pensée, p. 166.--Poissons, p. 20.--Polypes, p. 35.--Quadrumanes, pp. 131, 135, 136.--Radiaires, p. 32.--Raison, p. 125.--Reptiles, p. 18.--Sentiment, p. 177.--Troglodyte, p. 126.--Tableau du règne animal, p. 37.--Vie, p. 71. Mémoire sur la Tubicinelle. (Lu à l'Assemblée des Professeurs du Muséum d'Histoire naturelle.) Ann. Mus. Hist. nat., Paris, I, 1802. pp. 4, pl. 464. Bull. Soc. philom. III, Paris, 1801-1804. pp. 170-171. (Extrait.) Mémoires sur les Cabinets d'Histoire naturelle et particulièrement sur celui du Jardin des Plantes; contenant l'exposition du régime et de l'ordre qui conviennent à cet établissement, pour qu'il soit vraiment utile. Ext. des Ann. du Mus. (1802). Paris. in-4to. 15 p. Des diverses sortes de Cabinets où l'on rassemble des objets d'Histoire naturelle, p. 2. Vrais principes que l'on doit suivre dans l'institution d'un Cabinet d'Histoire naturelle, p. 3. Sur le Cabinet d'Histoire naturelle du Jardin des Plantes, p. 5. Hydrogéologie, ou recherches de l'influence générale des eaux sur surface du globe terrestre; sur les causes de l'existence du bassin des mers; de son déplacement et de son transport successif sur les différents points de la surface de ce globe; enfin, sur les changements que les corps vivants exercent sur la nature et l'état de cette surface. Paris, an X [1802]. 8vo. pp. 268. 1802-6 Mémoires sur les fossiles des environs de Paris, comprenant la détermination des espèces qui appartiennent aux animaux marins sans vertèbres, et dont la plupart sont figurés dans la Collection des Velins du Muséum. 1er Mémoire. Mollusques testacés dont on trouve les dépouilles fossiles dans les environs de Paris. Paris, Mus. Hist. nat. (Ann.) I, 1802. pp. 299-312; 383-391; 474-479. Paris, Mus. Hist. nat. (Ann.) II, 1803. pp. 57-64; 163-169; 217-227; 315-321; 385-391. Paris, Mus. Hist. nat. (Ann.) III, 1804. pp. 163-170; 266-274. Paris, Mus. Hist. nat. (Ann.) IV, 1804. pp. 46-55; 105-115; 211-222; 289-298; 429-436. Paris, Mus. Hist. nat. (Ann.) V, 1804. pp. 28-36; 91-98; 179-180; 237-245; 349-356. Paris, Mus. Hist. nat. (Ann.) VI, 1805. pp. 117-126; 214-221; 222-228; 337-345. Paris, Mus. Hist. nat. (Ann.) VII, 1806. pp. 53-62; 136-140; 231-242; 419-430. Paris, Mus. Hist. nat. (Ann.) VIII, 1806. pp. 156-166; 347-355; 461-469. Tirage à part. Paris. In-4to. 1806. pp. 284. 1er mémoire. Genres Chiton, Patella, Fissurella. pp. 308-312. 2e " " Emarginula, Calyptræa, Conus, Cypræa, Terebellum et Oliva. pp. 383-391. 3e mémoire. Genres Ancilla, Voluta. pp. 474-479. Paris, Mus. Hist. nat. (Ann.) I, 1802. 4e mémoire. Genres Mitra, Marginella, Cancellaria, Purpura. pp. 57-64. 5e mémoire. Genres Buccinum, Terebra, Harpa, Cassis. pp. 163-169. 6e mémoire. Genres Strombus, Rostellaria, Murex. pp. 217-227. 7e mémoire. Genre Fusus. pp. 315-321. 8e " Genres Fusus, Pyrula. pp. 385-391. Paris, Mus. Hist. nat. (Ann.) II, 1803. 9e mémoire. Genre Pleurotoma. pp. 163-170. 10e mémoire. Genres Pleurotoma, Cerithium. pp. 266-274. 11e et 12e mémoires. Genre Cerithium. pp. 343-352; 436-441. Paris, Mus. Hist. nat. (Ann.) III, 1804. 13e mémoire. Genres Trochus, Solarium. pp. 46-55. 14e " " Turbo, Delphinula, Cyclostoma. pp. 105-115. 15e mémoire. Genres Scalaria, Turritella, Bulla. pp. 212-222. 16e " " Bulimus, Phasianella, Lymnæa. pp. 289-298. 17e mémoire. Genres Melania, Auricula, pp. 429-436. Paris, Mus. Hist. nat. (Ann.) IV, 1804. 18e mémoire. Genres Volvaria, Ampullaria, Planorbis. pp. 28-36. 19e mémoire. Genres Helicina, Nerita, Natica. pp. 91-98. 20e " " Nautilus, Discorbis, Rotalia, Lenticulina. pp. 179-188. 21e mémoire. Genres Nummulites, Lituola, Spirolina. pp. 237-245. 22e mémoire. Genres Miliola, Renulina, Gyrogona. pp. 349-357. Paris, Mus. Hist. nat. (Ann.) V, 1804. 23e mémoire. Genres Pinna, Mytilus, Modiola, Nucula. pp. 117-126. 24e mémoire. Genres Pectunculus, Arca. pp. 214-221. 25e " " Cucullæa, Cardita, Cardium. pp. 337-346. 26e mémoire. Genres Crassatella, Mactra, Erycina. pp. 407-415. Paris, Mus. Hist. nat. (Ann.) VI, 1805. 27e mémoire. Genres Erycina, Venericardia, Venus. pp. 53-62. 28e " " Venus, Cytherea, Donax. pp. 130-140. 29e " " Tellina, Lucina. pp. 231-239. 30e " " Cyclas, Solen, Fistulana. pp. 419-430. Paris, Mus. Hist. nat. (Ann.) VII, 1806. 31e mémoire. Genre Ostrea. pp. 156-158. 32e " Genres Chama, Spondylus, Pecten. pp. 347-356. 33e mémoire. Genres Lima, Corbula. pp. 461-470. Paris, Mus. Hist. nat. (Ann.) VIII, 1806. Sur la crénatule, nouveau genre de coquillage. Pl. 2. Cr. avicularis.--Cr. mytiloides.--Cr. phasianoptera. Ann. Mus. Hist. nat., Paris, III, 1804. pp. 25-31, pl. 2. Sur deux nouveaux genres d'insectes de la Nouvelle Hollande: Chiroscelis bifenestra; p. 262. Panops Baudini; p. 265. Ann. Mus. Hist. nat., Paris, III, 1804. pp. 260-265. Sur une nouvelle espèce de Trigonie, et sur une nouvelle espèce d'Huître, découvertes dans le voyage du Capitaine Baudin. Trigonia suborbiculata; p. 355, pl. 4, fig. 1. Ostrea ovato-cuneiformis; p. 358, pl. 4, fig. 2. Ann. Mus. Hist. nat., Paris, IV, 1804. pp. 351-359. Mémoire sur deux nouvelles espèces de Volutes des mers de la Nouvelle Hollande. Voluta undulata; p. 157, pl. xii., fig. 1. Voluta nivosa; p. 158, pl. xii., fig. 2, 3. Ann. Mus. Hist. nat., Paris, V, 1804. pp. 154-160. Sur la Galathée, nouveau genre de coquillage bivalve. Galathea radiata. p. 433, pl. 28. Ann. Mus. Hist. nat., Paris, V, 1804. pp. 430-434. 1805 Considérations sur quelques faits applicables à la théorie du globe, observés par M. Péron dans son voyage aux terres australes, et sur quelques questions géologiques qui naissent de la connaissance de ces faits. (Observations zoologiques propres à constater l'ancien séjour de la mer sur le sommet des montagnes des îles de Diemen, de la Nouvelle Hollande et de l'île Timor.) Ann. Mus. Hist. nat., Paris, VI, 1805. pp. 26-52. Zusatz das Nordlicht am 22sten Octob., 1804, betreffend. (Translated from the Moniteur.) Gilbert Annal. XIX, 1805. pp. 143, 249-250. Sur la Dicerate, nouveau genre de coquillage bivalve. Diceras arietina. p. 300, pl. 55, fig. 2. Ann. Mus. Hist. nat., Paris, VI, 1805. pp. 298-302. Sur l'Amphibulime. A. cucullata. p. 305, pl. 55, fig. 1. Ann. Mus. Hist. nat., Paris, VI, 1805. pp. 303-306. Recherches asiatiques ou Mémoires de la Société établie au Bengale pour faire des recherches sur l'histoire et les antiquités, les arts, les sciences, etc., traduits de l'anglais par La Baume, revues et augmentés de notes, pour la partie orientale, par Langlès; pour la partie des sciences, par Lamarck, etc. Paris, 1805. 2 vol. 4to, av. pl. 1805-1809 Recueil de planches des coquilles fossiles des environs de Paris, avec leurs explications. On y a joint 2 planches de Lymnées fossiles et autres coquilles qui les accompagnent, des environs de Paris; par M. Brard. Ensemble 30 pl. gr. en taille douce. Paris (Dufour & d'Ocagne), 1823. In-4to. Explic. des 4 premières planches, 1-4. Paris, Mus. Hist. nat. (Ann.) VI, 1805. pp. 122-228, pl. 43-46. Explic. des 8 pl. suivantes, 5-7. Paris, Mus. Hist. nat. (Ann.) VII, 1806. pp. 442-444. pl. 13-15. Explic. des 3 pl. suivantes, 8-10. Paris, Mus. Hist. nat. (Ann.) VIII, 1806. pp. 77-78. pl. 35-37. Explic. des 4 pl. suivantes, 11-14. Paris, Mus. Hist. nat. (Ann.) VIII, 1806. pp. 383-388, pl. 59-62. Explic. des 4 pl. suivantes, 15-18. Paris, Mus. Hist. nat. (Ann.) IX, 1807. pp. 236-240, pl. 17-20. Explic. des 2 pl. suivantes, 19, 20. Paris, Mus. Hist. nat. (Ann.) IX, 1807. pp. 399-401, pl. 31-32. Explic. des 4 pl. suivantes, 21-24. Paris, Mus. Hist. nat. (Ann.) XII, 1808. pp. 456-459, pl. 40-43. Explic. des 4 pl. suivantes, 25-28. Paris, Mus. Hist. nat. (Ann.) XIV, 1809. pp. 374-375, pl. 20-23. 1806 Synopsis plantarum in Flora Gallica descriptarum. (En collab. avec A. P. Decandolle.) Paris (H. Agasse). 1806. 1 vol. 8vo. XXIV. 432 pp. Ordinum generumque anomalorum Clavis analytica. pp. i-xxiv. Discours d'Ouverture du Cours des Animaux sans Vertèbres, prononcé dans le Muséum d'Histoire naturelle en mai 1806. Paris, 1806. br., in-8vo. 1807 Sur la division des Mollusques acéphales conchylifères, et sur un nouveau genre de coquille appartenant à cette division (Etheria). Ann. Mus. X, 1807. pp. 389-408, 4 pl. Etwas über die Meteorologie. Gilbert Annal. XVII, 1807. pp. 355-359. Sur la division des Mollusques acéphalés conchylifères et sur un nouveau genre de coquille appartenant à cette division. (Genre Etheria.) Ann. Mus. Hist. nat., Paris, X, 1807. pp. 389-398. Sur l'Éthérie, nouveau genre de coquille bivalve de la famille des Camacées. Etheria elliptica; p. 401, pl. 29 et 31, fig. 1. Etheria trigonule; p. 403, pl. 30 et 31, fig. 2. Etheria semi-lunata; p. 404, pl. 32, fig. 1, 2. Etheria transversa; p. 406, pl. 32, fig. 3, 4. Ann. Mus. Hist. nat., Paris. X, 1807. pp. 398-408. (Ce mémoire se rattache au précédent.) 1809 Philosophie zoologique, ou exposition des considérations relatives à l'histoire naturelle des animaux; à la diversité de leur organisation et des facultés qu'ils en obtiennent; aux causes physiques qui maintiennent en eux la vie et donnent lieu aux mouvements qu'ils exécutent; enfin, à celles qui produisent, les unes les sentiments, et les autres l'intelligence de ceux qui en sont doués. Paris (Dentu), 1809. 2 vol. in-8vo, XXV, 428. 475 pages. _Idem_, nouvelle Édition. Paris, J. B. Baillière. 1830. (A reprint of the first edition.) 2me Édition. Revue et précédée d'une introduction biographique par Charles Martins. Paris. Savy. 1873. 2 vol. 8vo. LXXXIV. 412; 431 pages. Vol. I. Première Partie.--Considération sur l'histoire naturelle des animaux, leurs caractères, leurs rapports, leur organisation, leur distribution, leur classification et leurs espèces. Chap. I. Des parties de l'art dans les productions de la nature. p. 17. Chap. II. Importance de la considération des rapports. p. 39. Chap. III. De l'Espèce parmi les corps vivants et de l'idée que nous devons attacher à ce mot. p. 53. Chap. IV. Généralités sur les animaux. p. 82. Chap. V. Sur l'état actuel de la distribution et de la classification des animaux. p. 102. Chap. VI. Dégradation et simplification de l'organisation d'une extrémité à l'autre de la chaîne animale, en procédant du plus composé vers le plus simple. p. 130. Chap. VII. De l'influence des circonstances sur les actions et les habitudes des animaux, et de celle des actions et des habitudes de ces corps vivants, comme causes qui modifient leur organisation et leurs parties. p. 218. Chap. VIII. De l'ordre naturel des animaux, et de la disposition qu'il faut donner à leur distribution générale pour la rendre conforme à l'ordre même de la nature. p. 269. Deuxième Partie.--Considérations sur les causes physiques de la vie, les conditions qu'elle exige pour exister, la force excitatrice de ses mouvements, les facultés qu'elle donne aux corps qui la possèdent et les résultats de son existence dans ces corps. Chap. I. Comparaison des corps inorganiques avec les corps vivants, suivie d'une parallèle entre les animaux et les végétaux. p. 377. Chap. II. De la vie, de ce qui la constitue, et des conditions essentielles à son existence dans un corps. p. 400. Vol. II. 2me Partie. Chap. III. De la cause excitatrice des mouvements organiques. p. 1. Chap. IV. De l'orgasme et de l'irritabilité. p. 20. Chap. V. Du tissu cellulaire, considéré comme la gangue dans laquelle toute organisation a été formée. p. 46. Chap. VI. Des générations directes ou spontanées. p. 61. Chap. VII. Des résultats immédiats de la vie dans un corps. p. 91. Chap. VIII. Des facultés communes à tous les corps vivants. p. 113. Chap. IX. Des facultés particulières à certains corps vivants. p. 127. Troisième Partie.--Considérations sur les causes physiques du sentiment; celles qui constituent la force productrice des actions; enfin, celles qui donnent lieu aux actes d'intelligence qui s'observent dans différents animaux. p. 169. Chap. I. Du système nerveux, de sa formation et des différentes sortes de fonctions qu'il peut exciter. p. 180. Chap. II. Du fluide nerveux. p. 235. Chap. III. De la sensibilité et du mécanisme des sensations. p. 252. Chap. IV. Du sentiment intérieur, des émotions qu'il est susceptible d'éprouver, et de la puissance qu'il en acquiert pour la production des actions. p. 276. Chap. V. De la force productrice des actions des animaux, et de quelques faits particuliers qui résultent de l'emploi de cette force; p. 302. De la consommation et de l'épuisement du fluide nerveux dans la production des actions animales; p. 314. De l'origine du penchant aux mêmes actions; p. 318. De l'instinct des animaux; p. 320. De l'industrie de certains animaux; p. 327. Chap. VI. De la volonté. p. 330. Chap. VII. De l'entendement, de son origine, et de celle des idées. p. 346. Chap. VIII. Des principaux actes de l'entendement, ou de ceux du premier ordre dont tous les autres dérivent; p. 388. De l'imagination; p. 411. De la raison et de sa comparaison avec l'instinct; p. 441. (Ces notes ont été relevées sur l'édition de 1809.) 1810-1811 Sur la détermination des espèces parmi les animaux sans vertèbres, et particulièrement parmi les mollusques testacés. (Tirage à part, Paris, 1817. 4to. 5 pls.) Ann. Mus. Hist. nat., Paris, XV, 1810. pp. 20-26. Descript. des Espèces.--Cône (Conus). pp. 26-40; pp. 269-292; pp. 422-442. Descript. des Espèces.--Porcelaine (Cypræa). pp. 443-454. Ann. Mus. Hist. nat., Paris, XVI, 1810. Descript. des Espèces.--Porcelaine (Cypræa), suite, pp. 89-108. Descript. des Espèces.--Ovule (Ovula). pp. 109-114. " " " Tarrière (Terebellum). pp. 300-302. " " " Ancillaire (Ancillaria). pp. 302-306. " " " Olive (Oliva). pp. 306-328. Ann. Mus. Hist. nat. XVII, 1811. Descript. des Espèces.--Volute (Voluta). pp. 54-80. " " " Mitre (Mitra). pp. 195-222. Description des Espèces du Genre Conus. Ann. Muséum. XV. 1810. pp. 29-40, 263-292, 422-442. Description du genre Porcelaine (Cypræa) et des Espèces qui le composent. Ann. Mus. XV, 1810. pp. 443-454. Suite de la détermination des Espèces de Mollusques testacés. Continuation du genre Porcelaine. Ann. Mus. XVI, 1811. pp. 89-114. 1812 Extrait du cours de zoologie du Muséum d'Histoire naturelle sur les Animaux sans Vertèbres, présentant la distribution et classification de ces animaux, les caractères des principales divisions et une simple liste des genres, à l'usage de ceux qui suivent ce cours. Paris, octobre 1812. 8vo. pp. 127. 1813 Sur les polypiers empâtés. Ann. Mus. Hist. nat., Paris, XX, 1813. Pinceau (Penicillus). pp. 294, 297-299. Flabellaire (Flabellaria). pp. 298-303. Synoique (Synoicum). pp. 303-304. Éponge (Spongia). pp. 305-312; 370-386; 432-458. Ann. Mus. Hist. nat., Paris, I, 1815. Téthie (Tethya). pp. 69-71. Alcyon (Alcyonium). pp. 72-80; 162-168; 331-333. Géodie (Geodia). pp. 333-334. Botrylle (Botryllus). pp. 335-338. Polycycle (Polycyclus). pp. 338-340. 1813-15 Sur les polypiers corticifères. Mém. Mus. Hist. nat., Paris, I, 1813. p. 401. Corail (Coraillium). pp. 407-410. Mélite (Melitæa). pp. 410-413. Isis. pp. 413-416. Cymosaire (Cymosaria). pp. 467-468. Antipate (Antipathes). pp. 469-476. Mém. Mus. Hist. nat., Paris, II, 1815. Gorgone (Gorgonia). pp. 76-84; 157-164. Coralline (Corallina). pp. 227-240. Rapport fait à l'Institut (en collaboration avec Cuvier) sur les observations sur les Lombrics, ou les Vers de terre, etc., par Montègre. Paris, 1815. Br., in-8vo, 1 pl. 1815-22 Histoire naturelle des Animaux sans Vertèbres, présentant les caractères généraux et particuliers de ces animaux, leur distribution, leurs classes, leurs familles, leurs genres, et la citation des principales Espèces qui s'y rapportent; précédée d'une introduction offrant la détermination des caractères essentiels de l'Animal, sa distinction du Végétal et des autres corps naturels; enfin, l'exposition des principes fondamentaux de la zoologie. Paris, mars 1815 à août 1822. 7 vol. 8vo. 2e édit., Paris, 1835-45. 11 vol. in-8vo. 1818 Suite de la détermination des Espèces de Mollusques testacés. Genres Volute et Mitre. Ann. Mus. XVII, 1818. pp. 54-80 et 195-222. Description des genres Tarrière (Terebellum), Ancillaria et Oliva. Ann. Mus. XVII, 1818. pp. 300-328. 1820 Système analytique des connaissances de l'homme restreintes à celles qui proviennent directement ou indirectement de l'observation. Paris (Berlin), 1820. In-8vo. pp. 362. Première Partie.--Des Objets que l'homme peut considérer hors de lui, et que l'observation peut lui faire connaître, p. 13. Chap. I. De la Matière, p. 5. Chap. II. De la Nature; p. 20. Définition de la nature, et exposé des parties dont se compose l'ordre des choses qui la constitue; p. 50. Objets métaphysiques dont l'ensemble constitue la nature; p. 51. De la nécessité d'étudier la nature, c'est-à-dire l'ordre des choses qui la constitue, les lois qui régissent ses actes, et surtout, parmi ces lois, celles qui sont relatives à notre être physique; p. 60. Exposition des sources où l'homme a puisé les connaissances qu'il possède et dans lesquelles il pourra en recueillir quantité d'autres; sources dont l'ensemble constitue pour lui le champ des réalités; p. 85. Des Objets évidemment produits; p. 97. Chap. I. Des Corps inorganiques, p. 100. Chap. II. Des Corps vivants; p. 114. Des Végétaux; p. 125. Des Animaux; p. 134. Deuxième Partie.--De l'Homme et de certains systèmes organiques observés en lui, lesquels concourrent à l'exécution de ses actions; p. 149. Généralités sur le sentiment; p. 161. Analyse des phénomènes qui appartiennent au sentiment; p. 175. Sect. I.--De la sensation. p. 177. Chap. I. Des sensations particulières, p. 180. Chap. II. De la sensation générale. Sect. II.--Du sentiment intérieur et de ses principaux produits. p. 191. Chap. I. Des penchants naturels. p. 206. Chap. II. De l'instinct. p. 228. Sect. III.--De l'intelligence, des objets qu'elle emploie, et des phénomènes auxquels elle donne lieu. p. 255. Chap. I. Des idées. p. 290. Chap. II. Du jugement et de la raison. p. 325. Chap. III. Imagination. p. 348. 1823 Recueil de planches de coquilles fossiles des environs de Paris, avec leurs explications. On y a joint deux planches de Lymnées fossiles et autres coquilles qui les accompagnent, des environs de Paris; par M. Brard. Paris, 1823. 1 vol. in-4to de 30 pl. 1828 Histoire naturelle des Végétaux par Lamarck et Mirbel. Paris, Déterville (Roret). In-18mo. 15 vol., avec 120 pl. Cet ouvrage fait partie de Buffon: Cours complet d'Histoire naturelle (Edit. de Castel). 80 vol. in-18mo. Paris, 1799-1802. Déterville (Roret). Storia naturale de' vegetabili per famiglie con la citazione de la Classe et dell' ordine di Linnes, e l'indicazione dell' use che si puo far delle piante nelle arti, nel commercio, nell' agricultura, etc. Con disegni tratti dal naturale e un genere completo, secondo il sistema linneano, con de' rinvii alla famiglie naturali, di A. L. Jussieu. Da G. B. Lamarck e da B. Mirbel. Recata in lingua italiana dal A. Farini con note ed aggiunte. 3 Tom. de 5-7. Fasc. 1835-41. (Engelmann's Bibliothec. Hist. nat., 1846.) FOOTNOTES: [274] Prepared by M. G. Malloisel, with a few titles added by the author. EULOGIES AND BIOGRAPHICAL ARTICLES ON LAMARCK Geoffroy St. Hilaire, Étienne.--Discours sur Lamarck. (Recueil publié par l'Institut. 4to. Paris, 1829.) Cuvier, George.--Éloge de M. de Lamarck, par M. le Baron Cuvier. Lu à l'Académie des Sciences, le 26 novembre 1832. [No imprint.] Paris. (Trans. in Edinburgh New Philosophical Journ. No. 39.) Bourguin, L. B.--Les grands naturalistes français au commencement du XIXe siècle (Annales de la Société linnéenne du Département de Maine-et-Loire. 6me Année. Angers, 1863. 8vo. pp. 185-221). Introduction, pp. 185-193. Lacaze-Duthiers, H. de.--De Lamarck. (Cours de zoologie au Muséum d'Histoire naturelle.) Revue scientifique, 1866. Nos. 16-18-19. Memoir of Lamarck, by J. Duncan. See Jardine (Sir W.), Bart., The Naturalist's Library. Vol. 36, pp. 17-63. Edinburgh, 1843. Quatrefages, A. de.--Charles Darwin et ses précurseurs français. Étude sur le transformisme. Paris, 1870. 8vo. pp. 378. Martins, Charles.--Un naturaliste philosophe. Lamarck, sa vie et ses oeuvres. Extrait de la Revue des Deux Mondes. Livraison du 1er mars 1873. Paris. Haeckel, Ernst.--Die Naturanschauung von Darwin, Goethe und Lamarck. Vortrag in der ersten öffentlichen Sitzung der fünf und fünfzigsten Versammlung Deutscher Naturforscher und Aerzte zu Eisenach am 18 September 1882. Jena, 1882. 8vo. pp. 64. Perrier, Edmond.--La philosophie zoologique avant Darwin. Paris, 1884. pp. 292. Perrier, Edmond.--Lamarck et le transformisme actuel. (Extrait du volume commémoratif du Centenaire de la fondation du Muséum d'Histoire naturelle.) Paris, 1893. Folio. pp. 61. Bourguignat, J. R.--Lamarck, J. B. P. A. de Monnet de. (Biographical sketch, with a partial bibliography of his works, said to have been prepared by M. Bourguignat.) Revue biographique de la Société malacologique de France. Paris, 1886. pp. 61-85. With a portrait after Vaux-Bidon. Mortillet, Gabriel de.--Lamarck. Par G. de Mortillet. (L'Homme, IV, No. 1. 10 jan. 1887. pp. 1-8.) With portrait and handwriting, including autograph of Lamarck. Mortillet, Gabriel de, and others.--Lamarck. Par un groupe de transformistes, ses disciples. (Reprinted from L'Homme, IV. Paris, 1887. 8vo. pp. 31.) With portrait and figures. Mortillet, Gabriel de.--Réunion Lamarck. (La Société, l'École et le Laboratoire d'Anthropologie de Paris, à l'Exposition universelle de Paris.) Paris, 1889. pp. 72-84. Mortillet, Adrien de.--Recherches sur Lamarck (including acte de naissance, acte de décès, and letter from M. Mondière regarding his place of burial). L'Homme, IV, No. 10. Mai 25 1887. pp. 289-295. With portrait and view of the house he lived in. On p. 620, a note referring to a movement to erect a monument to Lamarck. Giard, Alfred.--Leçon d'ouverture du cours de l'évolution des êtres organisés. (Bull. sc. de la France et de la Belgique.) Paris, 1888. pp. 28. Portrait. Claus, Carl.--Lamarck als Begründer des Descendenzlehre. Wien, 1883. 8vo. pp. 35. Duval, Mathias.--Le transformiste français Lamarck. (Bull. Soc. d'Anthropologie de Paris. Tome XII, IIIe Série.) pp. 336-374. Lamarck.--Les maîtres de la science: Lamarck. Paris, 1892. G. Masson, Éditeur. 12mo. pp. 98. Hamy, E. T.--Les derniers jours du Jardin du Roi et la fondation du Muséum d'Histoire naturelle. pp. 40. (Extrait du volume commémoratif du Centenaire de la fondation du Muséum d'Histoire naturelle.) Paris, 10 juin 1893. Folio. pp. 162. Paris, 1893. Osborn, H. F.--From the Greeks to Darwin. An outline of the development of the evolution idea. New York. 1894. 8vo. pp. 259. Houssay, Frédéric.--Lamarck, son oeuvre et son esprit. Revue encyclopédique. Année 1897. pp. 969-973. Paris, Librairie Larousse. Hermanville, F. J. F.--Notice biographique sur Lamarck. Sa vie et ses oeuvres. Beauvais, 1898. 8vo. pp. 45. Portrait, after Thorel-Perrin. Packard, A. S.--Lamarck, and Neo-Lamarckism. (The Open Court. Feb., 1897.) Chicago, 1897. pp. 70-81. Packard, A. S.--Lamarck's Views on the Evolution of Man, on Morals, and on the Relation of Science to Religion. The Monist, Chicago, Oct., 1900. Chapters XVIII and XIX of the present work. INDEX Adaptation, 322, 367, 392, 412. Ærobates, 338. Ai, 320. Amphibia, 342. Ant-eater, 307, 313. Antlers, origin of, 316. Ant-lion, 337. Appetence, doctrine of, 219, 234, 236, 350, 412. Aspalax, 307. Atrophy, 274, 290, 303, 306, 307, 309, 311, 315, 343. Audouin J. V., 63. Barus, C., estimate of Lamarck's work in physics, 85. Batrachia, 342. Battle, law of, 219, 224. Beaver, 312. Besoins, 245, 270, 274, 281, 295, 302, 324, 334, 346, 350, 352, 412. Bird, humming, 313. Birds, domestic, atrophy in, 274; origin of, 342; origin of swimming, 234, 311; perching, 234, 312; shore, 234, 312. Blainville, H. D. de, 62, 64, 135. Blumenbach, 138. Bolton, H. C., 86. Bonnet, C., ideas on evolution, 156; germs, 163. Bosc, L. A. G., 52. Bourguin. L. B., 30, 31. Bradypus tridactylus, 320. Brain, 337, 360; human, 358. Bruguière, J. G., 38, 113. Buffalo, 315. Buffon, G. L. L., 19, 92, 198; factors of evolution, 205, 356; views on descent, 201. Bulla, 348. Callosities, origin of, 203. Camelo-pardalis, 316, 351. Carnivora, 317; origin of, 343. Catastrophism, 105, 117, 126, 146, 153; anti-, 105, 114, 153. Cave life, 390, 392. Cetacea, 343, 409; rudimentary teeth of, 307. Chain of being, 167, 181, 191, 208, 235, 241, 242. Changes in environment, 302; local, 301; slow, 301. Characters, acquired, heredity of, 219, 224, 246, 276, 303, 319. Chimpanzee, 367. Chiton, 348. Circumstances, influence of, 246, 247, 292, 294, 302, 305, 320, 323, 363, 400. Clam, origin of siphon of, 353, 418. Classifications, artificial, 282. Claws of birds, 312; Carnivora, 317, 414. Climate, 204, 218, 244, 283, 400, 402, 416. Coal, origin of, 113, 122. Colonies, animal, 411. Colors, animal, 221. Competition, 236, 287. Conditions, changes of, 292, 294, 302, 305, 310, 400, 407, 414. Consciousness, 325, 326, 353. Cope, E. D., 383, 389. Corals, 115. Correlation, law of, 136, 142, 145; of tertiary beds, 133. Costantin, 416. Creation by evolution, 130. Crossing, swamping effects of, 246, 320. Crustacea, origin of, 341. Cunningham, J. T., 409. Cuvier, George, 66, 140; eulogy on Lamarck, 65; first paper, 185. Dall, W. H., estimate of Lamarck's work, 196. Darkness, influence of, 308. Darwin, Charles, 423, 424; estimate of Lamarck's views, 73; factors tabulated, 356; origin of man, compared with Lamarck's, 371; views on descent, 217, 407. Darwin, Erasmus, factors of evolution, 217, 223, 356; life of, 216. Daubenton, 19, 26, 29, 136. Deer, 316. Degeneration, as used by Buffon, 204, 209; by Geoffroy, 213; by Lamarck, 182, 274, 290. Delboeuf's law, 406. Desiring, 236, 351, 412. Digits, modifications of, 234, 311, 317, 321, 338, 344; reduction of, 315. Direct action of environment, 324, 409, 410, 414, 416. Disuse, 274, 290, 296, 303, 306, 307, 311, 318, 343, 392, 412. Dixon, C., 405. Dogs, tailless, 220; domestication in, 299; races of, 299, 304. Domestic animals, 274, 304. Domestication, effects of, 298, 323. D'Orbigny, A., 386. Duck, 298, 312, 318. Duckbill, 412. Earth, great age of, 119; revolutions of, 109, 147, 150; theory of, 149. Earth's interior, 105. Effort, 213, 234, 257, 295, 339, 348, 351, 353, 354, 370, 411, 420. Egypt, mummied species of, 271, 286. Eigenmann, C. H., 393. Eimer, G. H. T., 408. Elephant, 315. Emotion, 353. Encasement theory, 162, 218, 222. Environment, 214, 410, 417, 421. Epigenesis, 156. Erosion, 101. Evil, 377. Evolution, dynamic, 417; Lamarck's views on, 322. Exercise, 211, 256. Existence, struggle for, 207, 237, 287. Extinct species, 126, 129, 130. Eyeless animals, 307, 309. Eyes, 308; of flounder, 313. Faujas de St. Fond, 23, 140. Feelings, internal, 324, 325, 330, 347. Fishes, flat, 313; form due to medium, 291; origin of, 341. Fittest, origin of, 383. Flamingo, 250. Flounder, 313. Flying mammals, origin of, 338. Fossilization, 120. Fossils, 109, 110, 112, 125, 138; deep-sea, 113; of Paris basin, 134. Frog, 312. Function, change of, 394. Galeopithecus, 339. Gasteropods, 348, 417. Generation, spontaneous, 158, 176, 201, 285. Geoffroy St. Hilaire, E., 36, 67, 307; factors tabulated, 356; life, 212; views on descent, 215; views on species, 213. Geographical distribution, 205, 246. Geological time, 119, 130, 222. Geology, Lamarck's work in, 100. Germs of life, first, 259, 261, 268; preëxistence of, 162, 218, 222. Giard, A., 406, 410. Giraffe, 316, 351, 411, 412. Goose, 298, 312, 313. Granite, origin of, 120, 149. Guettard, J. E., 95, 132, 136. Gulick, J. T., 405. Habits, 235, 247, 295, 303, 305, 314, 316, 321, 323, 324, 340, 394. Haeckel, E., 385; estimate of Lamarck's theory, 69. Hamy, E. T., 19, 22, 25. Hearing, 308. Henslow, G., 414. Heredity, 250, 276, 303, 306, 319, 336; of acquired characters, 219, 224, 246, 276, 303, 319. Hertwig, R., 282. Hoofs, origin of, 315. Hooke, Robert, 132. Horns, origin of, 316, 354, 393, 409. Horse, 274, 304, 315. Hutton, James, 99. Huxley, T. H., 423, 424; estimate of Lamarck's scientific position, 74, 90. Hyatt, A., 386, 419. Hybridity, 223. Hybrids, 284. Hydrogéologie, 89. Imitation, 361. Indirect action of environment, 324, 409. Industry, animal, 336. Infusoria, 328. Insects, wingless, 309. Intestines of man, 310. Instinct, 223, 286, 330, 331, 332, 349; variations in, 335, 337, 349. Isolation, 392, 394, 404; in man, 320, 369. Jacko, 364. Jardin des Plantes, 23. Jeffries, J. A., 413. Jordan, K., 410. Juncus bufonius, 252. Kangaroo, 318. Lacaze-Duthiers, H. de, reminiscences of Lamarck, 75. Lakanal, J., 28. Lamarck, Cornelie de, 55. Lamarck, J. B. de, birth, 6; birthplace, 4; blindness, 51; botanical career, 15, 19, 173; burial place, 57; death, 51; estimates of his life-work, 69; factors at evolution, 233, 356; founder of palæontology, 124; house in Paris, 42; meteorology and physical science, 79; military career, 11; origin of man, 357; parentage, 7; share in reorganization of Museum, 24; shells, collections of, 46; on spontaneous generation, 158; style, 179; travels, 20; views on religion, 372; work in geology, 89; zoölogical work, 32, 180. Lamarckism, relations to Darwinism, 382. Land, changes of level of, 107. Latreille, P. A., 62. Law of battle, 219, 224. Laws of evolution, Lamarck's, 303, 346. Legs, atrophy of, 290, 309, 343. Lemur volans, 339. Life, 346; conditions of, 292, 294, 302, 305, 310, 400, 414; definitions of, 168, 169, 280. Light, 410. Limbs, atrophy of, 290, 309; genesis of, 421; of seal, 338, 344; whale, 343. Lizard, 313. Local changes, 301. Lyell, Charles, estimate of Lamarck's theory, 71. Mammals, aquatic, 343; flying, 338. Man, as a check on animal life, 288; origin of, 357; origin of language, 370; origin of his plantigrade feet, 365; posture, 362, 368; relation to apes, 362; segregation of, from apes, 369; shape of his skull, 365; sign-language, 368; speech, origin of, 370; swamping effects of crossing in, 320. Medium, 214. Milieu, 214, 416. Mimicry, protective, 220, 221, 225. Minerals, growth of, 164. Mole, 307. Molluscs, 420; eyeless, 309; gasteropod, 348; pelecypod, 417; lamellibranch, 418; Lamarck's work on, 189. Monet, de, 8. Monotremes, origin from birds, 342. Morals, 372. Mortillet, G. de, 30. Mountains formed by erosion, 101, 103. Muscles, adductor, 418. Museum of Natural History, Paris, 34. Mya arenaria, 353, 418. Myrmecophaga, 307. Myrmeleon, 337. Nails, 321. Natural selection. Inadequacy of, 393, 397, 401, 407, 410, 413, 415, 421, 423. Nature, balance of, 207; definition of, 169, 345, 375. Neck, elongation of, in birds, 274, 311, 317; giraffe, 316, 351; ostrich, 317. Needs, 245, 270, 274, 281, 295, 302, 324, 334, 346, 350, 351, 352. Neodarwinism, 422. Neolamarckism, 2, 382, 396, 398, 422. Ophidia, atrophy of legs of, 290, 309. Organic sense, 325, 327, 336. Organs, changes in, 310; origin of, precedes their use, 223; follows their use, 305, 346; atrophy of, 274, 290, 303, 306, 307, 309, 311, 315; new production of, 346, 412, 420. Orang-outang, 364. Osborn, H. S., 403. Ostrich, 317. Otter, 312. Ox, 315. Oyster, 419. Palæontology, 136; Invertebrate, 135, 149. Pallas, 137. Penchants, 281, 293, 328, 331. Perrier, E., 26,411. Petaurista, 338. Philosophy, moral, Lamarck's, 379. Phoca vitulina, 338, 344. Phylogeny, 130. Pigeons, 298; fantail, 304. Planorbis, 387. Plants, changes due to cultivation, etc., 251, 267, 274, 283, 296, 297; cultivated, 298. Population, over-, checks on, 287, 288. Preformation, 162, 218, 222. Propensities, 281, 293, 328, 335, 349, 351. Proteus, 308. Pteromys, 339. Ranunculus Aquatilis, 251, 300. Religion and science, 372. Reptiles, 342. Revolutions of the earth, 109, 142. Rousseau, J. J., 17, 18. Roux, W., 421. Ruminants, 315. Ryder, J. A., 403. Science and Religion, 372. Sciurus volans, 338. Scott, W. B., 403. Sea, former existence of, 109, 110, 148. Seal, 338, 344. Segments, origin of, 421. Segregation, in man, 320, 369. Selection, mechanical, 410. Semper, C., 406. Series, animal, branching, 235, 264, 282. Serpents, origin of, 290, 309; eyes of, 314. Sexual selection, 219, 224. Shell, bivalve, origin of, 418; crustacean, 418. Shells, deep-water, 112; fossil, 40, 120, 125, 131; Lamarckian genera, 183. Simia satyrus, 367; troglodytes, 364. Sloth, 320. Snakes, atrophy of legs of, 290, 309; eyes of, 314; origin of, 290, 309; tongue of, 313. Sole, 314. Species, Buffon's views on, 201, 221; definition of, 252, 255, 262, 267, 275; extinct, 126; Geoffroy St. Hilaire, views on, 214; Lamarck's views on, 183; modification of, 131; origin of, 131, 283; stability of, 271, 277, 401; variation in, 278. Speech, 370. Spencer, Herbert, 371, 382, 384, 415. Spermist, 218. Sphalax, 307. Spines, 251, 393, 414. Sponges, 194. Squirrel, flying, 338, 339. Stimulus, external, 348, 354, 393. Struggle for existence, 207, 237, 287. Surroundings, 214, 421; local, 410. Symmetry, radial, 291. Swan, 313. Tail, of kangaroo, 318. Teeth, 307; atrophy of, 307; in embryo birds, 307; in whales, 307. Temperature, 410. Tentacles of snail, 348, 354. Tertiary shells, 110, 125, 133. Thought, definition of, 172. Time, geological, 119, 130, 222, 236. Toes, modifications of, 234, 311, 315, 317, 321, 338, 344. Tree, genealogical, first, 130, 181, 192, 193, 349. Trout, 403. Tubercles, origin of, 394. Tunicata, position of, 195. Turbot, 314. Turtle, sea, 312. Uniformitarianism, 130. Use, 248, 256, 257, 302, 303, 311, 318, 384, 412. Use-inheritance, 219, 224, 246, 276, 303, 319, 346. Use originates organs, 276, 311, 346. Variability, 407. Variation, climatic, 204, 218, 401; causes of, 218, 266. Varieties, 401. Varigny, H. de, 408. Vestigial organs, 307, 308. Vital force, 167. Vitalism, 168. Volucella, 338. Wagner, M., 404. Wallace, A. R., on origin of giraffe's neck, 351. Wants, 245, 270, 274, 281, 295, 302, 324, 334, 346, 350, 351, 352. Ward, L. F., 422. Water, diversified condition of, 290. Werner, 97. Whale, 307, 343, 409. Will, 319, 330, 337. Willing, 236, 351, 412. Weismann, A., 399. Wings, atrophy of, in insects, 309. Woodpecker, 313. 
2924	----	THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND VARIATION By Thomas Henry Huxley The inquiry which we undertook, at our last meeting, into the state of our knowledge of the causes of the phenomena of organic nature,--of the past and of the present,--resolved itself into two subsidiary inquiries: the first was, whether we know anything, either historically or experimentally, of the mode of origin of living beings; the second subsidiary inquiry was, whether, granting the origin, we know anything about the perpetuation and modifications of the forms of organic beings. The reply which I had to give to the first question was altogether negative, and the chief result of my last lecture was, that, neither historically nor experimentally, do we at present know anything whatsoever about the origin of living forms. We saw that, historically, we are not likely to know anything about it, although we may perhaps learn something experimentally; but that at present we are an enormous distance from the goal I indicated. I now, then, take up the next question, What do we know of the reproduction, the perpetuation, and the modifications of the forms of living beings, supposing that we have put the question as to their origination on one side, and have assumed that at present the causes of their origination are beyond us, and that we know nothing about them? Upon this question the state of our knowledge is extremely different; it is exceedingly large, and, if not complete, our experience is certainly most extensive. It would be impossible to lay it all before you, and the most I can do, or need do to-night, is to take up the principal points and put them before you with such prominence as may subserve the purposes of our present argument. The method of the perpetuation of organic beings is of two kinds,--the asexual and the sexual. In the first the perpetuation takes place from and by a particular act of an individual organism, which sometimes may not be classed as belonging to any sex at all. In the second case, it is in consequence of the mutual action and interaction of certain portions of the organisms of usually two distinct individuals,--the male and the female. The cases of asexual perpetuation are by no means so common as the cases of sexual perpetuation; and they are by no means so common in the animal as in the vegetable world. You are all probably familiar with the fact, as a matter of experience, that you can propagate plants by means of what are called "cuttings;" for example, that by taking a cutting from a geranium plant, and rearing it properly, by supplying it with light and warmth and nourishment from the earth, it grows up and takes the form of its parent, having all the properties and peculiarities of the original plant. Sometimes this process, which the gardener performs artificially, takes place naturally; that is to say, a little bulb, or portion of the plant, detaches itself, drops off, and becomes capable of growing as a separate thing. That is the case with many bulbous plants, which throw off in this way secondary bulbs, which are lodged in the ground and become developed into plants. This is an asexual process, and from it results the repetition or reproduction of the form of the original being from which the bulb proceeds. Among animals the same thing takes place. Among the lower forms of animal life, the infusorial animalculae we have already spoken of throw off certain portions, or break themselves up in various directions, sometimes transversely or sometimes longitudinally; or they may give off buds, which detach themselves and develop into their proper forms. There is the common fresh-water Polype, for instance, which multiplies itself in this way. Just in the same way as the gardener is able to multiply and reproduce the peculiarities and characters of particular plants by means of cuttings, so can the physiological experimentalist--as was shown by the Abbe Trembley many years ago--so can he do the same thing with many of the lower forms of animal life. M. de Trembley showed that you could take a polype and cut it into two, or four, or many pieces, mutilating it in all directions, and the pieces would still grow up and reproduce completely the original form of the animal. These are all cases of asexual multiplication, and there are other instances, and still more extraordinary ones, in which this process takes place naturally, in a more hidden, a more recondite kind of way. You are all of you familiar with those little green insects, the 'Aphis' or blight, as it is called. These little animals, during a very considerable part of their existence, multiply themselves by means of a kind of internal budding, the buds being developed into essentially asexual animals, which are neither male nor female; they become converted into young 'Aphides', which repeat the process, and their offspring after them, and so on again; you may go on for nine or ten, or even twenty or more successions; and there is no very good reason to say how soon it might terminate, or how long it might not go on if the proper conditions of warmth and nourishment were kept up. Sexual reproduction is quite a distinct matter. Here, in all these cases, what is required is the detachment of two portions of the parental organisms, which portions we know as the egg and the spermatozoon. In plants it is the ovule and the pollen-grain, as in the flowering plants, or the ovule and the antherozooid, as in the flowerless. Among all forms of animal life, the spermatozoa proceed from the male sex, and the egg is the product of the female. Now, what is remarkable about this mode of reproduction is this, that the egg by itself, or the spermatozoa by themselves, are unable to assume the parental form; but if they be brought into contact with one another, the effect of the mixture of organic substances proceeding from two sources appears to confer an altogether new vigour to the mixed product. This process is brought about, as we all know, by the sexual intercourse of the two sexes, and is called the act of impregnation. The result of this act on the part of the male and female is, that the formation of a new being is set up in the ovule or egg; this ovule or egg soon begins to be divided and subdivided, and to be fashioned into various complex organisms, and eventually to develop into the form of one of its parents, as I explained in the first lecture. These are the processes by which the perpetuation of organic beings is secured. Why there should be the two modes--why this re-invigoration should be required on the part of the female element we do not know; but it is most assuredly the fact, and it is presumable, that, however long the process of asexual multiplication could be continued, I say there is good reason to believe that it would come to an end if a new commencement were not obtained by a conjunction of the two sexual elements. That character which is common to these two distinct processes is this, that, whether we consider the reproduction, or perpetuation, or modification of organic beings as they take place asexually, or as they may take place sexually,--in either case, I say, the offspring has a constant tendency to assume, speaking generally, the character of the parent. As I said just now, if you take a slip of a plant, and tend it with care, it will eventually grow up and develop into a plant like that from which it had sprung; and this tendency is so strong that, as gardeners know, this mode of multiplying by means of cuttings is the only secure mode of propagating very many varieties of plants; the peculiarity of the primitive stock seems to be better preserved if you propagate it by means of a slip than if you resort to the sexual mode. Again, in experiments upon the lower animals, such as the polype, to which I have referred, it is most extraordinary that, although cut up into various pieces, each particular piece will grow up into the form of the primitive stock; the head, if separated, will reproduce the body and the tail; and if you cut off the tail, you will find that that will reproduce the body and all the rest of the members, without in any way deviating from the plan of the organism from which these portions have been detached. And so far does this go, that some experimentalists have carefully examined the lower orders of animals,--among them the Abbe Spallanzani, who made a number of experiments upon snails and salamanders,--and have found that they might mutilate them to an incredible extent; that you might cut off the jaw or the greater part of the head, or the leg or the tail, and repeat the experiment several times, perhaps, cutting off the same member again and again; and yet each of those types would be reproduced according to the primitive type: nature making no mistake, never putting on a fresh kind of leg, or head, or tail, but always tending to repeat and to return to the primitive type. It is the same in sexual reproduction: it is a matter of perfectly common experience, that the tendency on the part of the offspring always is, speaking broadly, to reproduce the form of the parents. The proverb has it that the thistle does not bring forth grapes; so, among ourselves, there is always a likeness, more or less marked and distinct, between children and their parents. That is a matter of familiar and ordinary observation. We notice the same thing occurring in the cases of the domestic animals--dogs, for instance, and their offspring. In all these cases of propagation and perpetuation, there seems to be a tendency in the offspring to take the characters of the parental organisms. To that tendency a special name is given--it is called 'Atavism', it expresses this tendency to revert to the ancestral type, and comes from the Latin word 'atavus', ancestor. Well, this 'Atavism' which I shall speak of, is, as I said before, one of the most marked and striking tendencies of organic beings; but, side by side with this hereditary tendency there is an equally distinct and remarkable tendency to variation. The tendency to reproduce the original stock has, as it were, its limits, and side by side with it there is a tendency to vary in certain directions, as if there were two opposing powers working upon the organic being, one tending to take it in a straight line, and the other tending to make it diverge from that straight line, first to one side and then to the other. So that you see these two tendencies need not precisely contradict one another, as the ultimate result may not always be very remote from what would have been the case if the line had been quite straight. This tendency to variation is less marked in that mode of propagation which takes place asexually; it is in that mode that the minor characters of animal and vegetable structures are most completely preserved. Still, it will happen sometimes, that the gardener, when he has planted a cutting of some favourite plant, will find, contrary to his expectation, that the slip grows up a little different from the primitive stock--that it produces flowers of a different colour or make, or some deviation in one way or another. This is what is called the 'sporting' of plants. In animals the phenomena of asexual propagation are so obscure, that at present we cannot be said to know much about them; but if we turn to that mode of perpetuation which results from the sexual process, then we find variation a perfectly constant occurrence, to a certain extent; and, indeed, I think that a certain amount of variation from the primitive stock is the necessary result of the method of sexual propagation itself; for, inasmuch as the thing propagated proceeds from two organisms of different sexes and different makes and temperaments, and as the offspring is to be either of one sex or the other, it is quite clear that it cannot be an exact diagonal of the two, or it would be of no sex at all; it cannot be an exact intermediate form between that of each of its parents--it must deviate to one side or the other. You do not find that the male follows the precise type of the male parent, nor does the female always inherit the precise characteristics of the mother,--there is always a proportion of the female character in the male offspring, and of the male character in the female offspring. That must be quite plain to all of you who have looked at all attentively on your own children or those of your neighbours; you will have noticed how very often it may happen that the son shall exhibit the maternal type of character, or the daughter possess the characteristics of the father's family. There are all sorts of intermixtures and intermediate conditions between the two, where complexion, or beauty, or fifty other different peculiarities belonging to either side of the house, are reproduced in other members of the same family. Indeed, it is sometimes to be remarked in this kind of variation, that the variety belongs, strictly speaking, to neither of the immediate parents; you will see a child in a family who is not like either its father or its mother; but some old person who knew its grandfather or grandmother, or, it may be, an uncle, or, perhaps, even a more distant relative, will see a great similarity between the child and one of these. In this way it constantly happens that the characteristic of some previous member of the family comes out and is reproduced and recognised in the most unexpected manner. But apart from that matter of general experience, there are some cases which put that curious mixture in a very clear light. You are aware that the offspring of the Ass and the Horse, or rather of the he-Ass and the Mare, is what is called a Mule; and, on the other hand, the offspring of the Stallion and the she-Ass is what is called a 'Hinny'. I never saw one myself; but they have been very carefully studied. Now, the curious thing is this, that although you have the same elements in the experiment in each case, the offspring is entirely different in character, according as the male influence comes from the Ass or the Horse. Where the Ass is the male, as in the case of the Mule, you find that the head is like that of the Ass, that the ears are long, the tail is tufted at the end, the feet are small, and the voice is an unmistakable bray; these are all points of similarity to the Ass; but, on the other hand, the barrel of the body and the cut of the neck are much more like those of the Mare. Then, if you look at the Hinny,--the result of the union of the Stallion and the she-Ass, then you find it is the Horse that has the predominance; that the head is more like that of the Horse, the ears are shorter, the legs coarser, and the type is altogether altered; while the voice, instead of being a bray, is the ordinary neigh of the Horse. Here, you see, is a most curious thing: you take exactly the same elements, Ass and Horse, but you combine the sexes in a different manner, and the result is modified accordingly. You have in this case, however, a result which is not general and universal--there is usually an important preponderance, but not always on the same side. Here, then, is one intelligible, and, perhaps, necessary cause of variation: the fact, that there are two sexes sharing in the production of the offspring, and that the share taken by each is different and variable, not only for each combination, but also for different members of the same family. Secondly, there is a variation, to a certain extent--though, in all probability, the influence of this cause has been very much exaggerated--but there is no doubt that variation is produced, to a certain extent, by what are commonly known as external conditions,--such as temperature, food, warmth, and moisture. In the long run, every variation depends, in some sense, upon external conditions, seeing that everything has a cause of its own. I use the term "external conditions" now in the sense in which it is ordinarily employed: certain it is, that external conditions have a definite effect. You may take a plant which has single flowers, and by dealing with the soil, and nourishment, and so on, you may by-and-by convert single flowers into double flowers, and make thorns shoot out into branches. You may thicken or make various modifications in the shape of the fruit. In animals, too, you may produce analogous changes in this way, as in the case of that deep bronze colour which persons rarely lose after having passed any length of time in tropical countries. You may also alter the development of the muscles very much, by dint of training; all the world knows that exercise has a great effect in this way; we always expect to find the arm of a blacksmith hard and wiry, and possessing a large development of the brachial muscles. No doubt training, which is one of the forms of external conditions, converts what are originally only instructions, teachings, into habits, or, in other words, into organizations, to a great extent; but this second cause of variation cannot be considered to be by any means a large one. The third cause that I have to mention, however, is a very extensive one. It is one that, for want of a better name, has been called "spontaneous variation;" which means that when we do not know anything about the cause of phenomena, we call it spontaneous. In the orderly chain of causes and effects in this world, there are very few things of which it can be said with truth that they are spontaneous. Certainly not in these physical matters,--in these there is nothing of the kind,--everything depends on previous conditions. But when we cannot trace the cause of phenomena, we call them spontaneous. Of these variations, multitudinous as they are, but little is known with perfect accuracy. I will mention to you some two or three cases, because they are very remarkable in themselves, and also because I shall want to use them afterwards. Reaumur, a famous French naturalist, a great many years ago, in an essay which he wrote upon the art of hatching chickens,--which was indeed a very curious essay,--had occasion to speak of variations and monstrosities. One very remarkable case had come under his notice of a variation in the form of a human member, in the person of a Maltese, of the name of Gratio Kelleia, who was born with six fingers upon each hand, and the like number of toes to each of his feet. That was a case of spontaneous variation. Nobody knows why he was born with that number of fingers and toes, and as we don't know, we call it a case of "spontaneous" variation. There is another remarkable case also. I select these, because they happen to have been observed and noted very carefully at the time. It frequently happens that a variation occurs, but the persons who notice it do not take any care in noting down the particulars, until at length, when inquiries come to be made, the exact circumstances are forgotten; and hence, multitudinous as may be such "spontaneous" variations, it is exceedingly difficult to get at the origin of them. The second case is one of which you may find the whole details in the "Philosophical Transactions" for the year 1813, in a paper communicated by Colonel Humphrey to the President of the Royal Society,--"On a new Variety in the Breed of Sheep," giving an account of a very remarkable breed of sheep, which at one time was well known in the northern states of America, and which went by the name of the Ancon or the Otter breed of sheep. In the year 1791, there was a farmer of the name of Seth Wright in Massachusetts, who had a flock of sheep, consisting of a ram and, I think, of some twelve or thirteen ewes. Of this flock of ewes, one at the breeding-time bore a lamb which was very singularly formed; it had a very long body, very short legs, and those legs were bowed! I will tell you by-and-by how this singular variation in the breed of sheep came to be noted, and to have the prominence that it now has. For the present, I mention only these two cases; but the extent of variation in the breed of animals is perfectly obvious to any one who has studied natural history with ordinary attention, or to any person who compares animals with others of the same kind. It is strictly true that there are never any two specimens which are exactly alike; however similar, they will always differ in some certain particular. Now let us go back to Atavism,--to the hereditary tendency I spoke of. What will come of a variation when you breed from it, when Atavism comes, if I may say so, to intersect variation? The two cases of which I have mentioned the history, give a most excellent illustration of what occurs. Gratio Kelleia, the Maltese, married when he was twenty-two years of age, and, as I suppose there were no six-fingered ladies in Malta, he married an ordinary five-fingered person. The result of that marriage was four children; the first, who was christened Salvator, had six fingers and six toes, like his father; the second was George, who had five fingers and toes, but one of them was deformed, showing a tendency to variation; the third was Andre; he had five fingers and five toes, quite perfect; the fourth was a girl, Marie; she had five fingers and five toes, but her thumbs were deformed, showing a tendency toward the sixth. These children grew up, and when they came to adult years, they all married, and of course it happened that they all married five-fingered and five-toed persons. Now let us see what were the results. Salvator had four children; they were two boys, a girl, and another boy; the first two boys and the girl were six-fingered and six-toed like their grandfather; the fourth boy had only five fingers and five toes. George had only four children; there were two girls with six fingers and six toes; there was one girl with six fingers and five toes on the right side, and five fingers and five toes on the left side, so that she was half and half. The last, a boy, had five fingers and five toes. The third, Andre, you will recollect, was perfectly well-formed, and he had many children whose hands and feet were all regularly developed. Marie, the last, who, of course, married a man who had only five fingers, had four children; the first, a boy, was born with six toes, but the other three were normal. Now observe what very extraordinary phenomena are presented here. You have an accidental variation arising from what you may call a monstrosity; you have that monstrosity tendency or variation diluted in the first instance by an admixture with a female of normal construction, and you would naturally expect that, in the results of such an union, the monstrosity, if repeated, would be in equal proportion with the normal type; that is to say, that the children would be half and half, some taking the peculiarity of the father, and the others being of the purely normal type of the mother; but you see we have a great preponderance of the abnormal type. Well, this comes to be mixed once more with the pure, the normal type, and the abnormal is again produced in large proportion, notwithstanding the second dilution. Now what would have happened if these abnormal types had intermarried with each other; that is to say, suppose the two boys of Salvator had taken it into their heads to marry their first cousins, the two first girls of George, their uncle? You will remember that these are all of the abnormal type of their grandfather. The result would probably have been, that their offspring would have been in every case a further development of that abnormal type. You see it is only in the fourth, in the person of Marie, that the tendency, when it appears but slightly in the second generation, is washed out in the third, while the progeny of Andre, who escaped in the first instance, escape altogether. We have in this case a good example of nature's tendency to the perpetuation of a variation. Here it is certainly a variation which carried with it no use or benefit; and yet you see the tendency to perpetuation may be so strong, that, notwithstanding a great admixture of pure blood, the variety continues itself up to the third generation, which is largely marked with it. In this case, as I have said, there was no means of the second generation intermarrying with any but five-fingered persons, and the question naturally suggests itself, What would have been the result of such marriage? Reaumur narrates this case only as far as the third generation. Certainly it would have been an exceedingly curious thing if we could have traced this matter any further; had the cousins intermarried, a six-fingered variety of the human race might have been set up. To show you that this supposition is by no means an unreasonable one, let me now point out what took place in the case of Seth Wright's sheep, where it happened to be a matter of moment to him to obtain a breed or raise a flock of sheep like that accidental variety that I have described--and I will tell you why. In that part of Massachusetts where Seth Wright was living, the fields were separated by fences, and the sheep, which were very active and robust, would roam abroad, and without much difficulty jump over these fences into other people's farms. As a matter of course, this exuberant activity on the part of the sheep constantly gave rise to all sorts of quarrels, bickerings, and contentions among the farmers of the neighbourhood; so it occurred to Seth Wright, who was, like his successors, more or less 'cute, that if he could get a stock of sheep like those with the bandy legs, they would not be able to jump over the fences so readily, and he acted upon that idea. He killed his old ram, and as soon as the young one arrived at maturity, he bred altogether from it. The result was even more striking than in the human experiment which I mentioned just now. Colonel Humphreys testifies that it always happened that the offspring were either pure Ancons or pure ordinary sheep; that in no case was there any mixing of the Ancons with the others. In consequence of this, in the course of a very few years, the farmer was able to get a very considerable flock of this variety, and a large number of them were spread throughout Massachusetts. Most unfortunately, however--I suppose it was because they were so common--nobody took enough notice of them to preserve their skeletons; and although Colonel Humphreys states that he sent a skeleton to the President of the Royal Society at the same time that he forwarded his paper, I am afraid that the variety has entirely disappeared; for a short time after these sheep had become prevalent in that district, the Merino sheep were introduced; and as their wool was much more valuable, and as they were a quiet race of sheep, and showed no tendency to trespass or jump over fences, the Otter breed of sheep, the wool of which was inferior to that of the Merino, was gradually allowed to die out. You see that these facts illustrate perfectly well what may be done if you take care to breed from stocks that are similar to each other. After having got a variation, if, by crossing a variation with the original stock, you multiply that variation, and then take care to keep that variation distinct from the original stock, and make them breed together,--then you may almost certainly produce a race whose tendency to continue the variation is exceedingly strong. This is what is called "selection"; and it is by exactly the same process as that by which Seth Wright bred his Ancon sheep, that our breeds of cattle, dogs, and fowls, are obtained. There are some possibilities of exception, but still, speaking broadly, I may say that this is the way in which all our varied races of domestic animals have arisen; and you must understand that it is not one peculiarity or one characteristic alone in which animals may vary. There is not a single peculiarity or characteristic of any kind, bodily or mental, in which offspring may not vary to a certain extent from the parent and other animals. Among ourselves this is well known. The simplest physical peculiarity is mostly reproduced. I know a case of a man whose wife has the lobe of one of her ears a little flattened. An ordinary observer might scarcely notice it, and yet every one of her children has an approximation to the same peculiarity to some extent. If you look at the other extreme, too, the gravest diseases, such as gout, scrofula, and consumption, may be handed down with just the same certainty and persistence as we noticed in the perpetuation of the bandy legs of the Ancon sheep. However, these facts are best illustrated in animals, and the extent of the variation, as is well known, is very remarkable in dogs. For example, there are some dogs very much smaller than others; indeed, the variation is so enormous that probably the smallest dog would be about the size of the head of the largest; there are very great variations in the structural forms not only of the skeleton but also in the shape of the skull, and in the proportions of the face and the disposition of the teeth. The Pointer, the Retriever, Bulldog, and the Terrier, differ very greatly, and yet there is every reason to believe that every one of these races has arisen from the same source,--that all the most important races have arisen by this selective breeding from accidental variation. A still more striking case of what may be done by selective breeding, and it is a better case, because there is no chance of that partial infusion of error to which I alluded, has been studied very carefully by Mr. Darwin,--the case of the domestic pigeons. I dare say there may be some among you who may be pigeon 'fanciers', and I wish you to understand that in approaching the subject, I would speak with all humility and hesitation, as I regret to say that I am not a pigeon fancier. I know it is a great art and mystery, and a thing upon which a man must not speak lightly; but I shall endeavour, as far as my understanding goes, to give you a summary of the published and unpublished information which I have gained from Mr. Darwin. Among the enormous variety,--I believe there are somewhere about a hundred and fifty kinds of pigeons,--there are four kinds which may be selected as representing the extremest divergences of one kind from another. Their names are the Carrier, the Pouter, the Fantail, and the Tumbler. In the large diagrams they are each represented in their relative sizes to each other. This first one is the Carrier; you will notice this large excrescence on its beak; it has a comparatively small head; there is a bare space round the eyes; it has a long neck, a very long beak, very strong legs, large feet, long wings, and so on. The second one is the Pouter, a very large bird, with very long legs and beak. It is called the Pouter because it is in the habit of causing its gullet to swell up by inflating it with air. I should tell you that all pigeons have a tendency to do this at times, but in the Pouter it is carried to an enormous extent. The birds appear to be quite proud of their power of swelling and puffing themselves out in this way; and I think it is about as droll a sight as you can well see to look at a cage full of these pigeons puffing and blowing themselves out in this ridiculous manner. The third kind I mentioned--the Fantail--is a small bird, with exceedingly small legs and a very small beak. It is most curiously distinguished by the size and extent of its tail, which, instead of containing twelve feathers, may have many more,--say thirty, or even more--I believe there are some with as many as forty-two. This bird has a curious habit of spreading out the feathers of its tail in such a way that they reach forward, and touch its head; and if this can be accomplished, I believe it is looked upon as a point of great beauty. But here is the last great variety,--the Tumbler; and of that great variety, one of the principal kinds, and one most prized, is the specimen represented here--the short-faced Tumbler. Its beak is reduced to a mere nothing. Just compare the beak of this one and that of the first one, the Carrier--I believe the orthodox comparison of the head and beak of a thoroughly well-bred Tumbler is to stick an oat into a cherry, and that will give you the proper relative proportions of the head and beak. The feet and legs are exceedingly small, and the bird appears to be quite a dwarf when placed side by side with this great Carrier. These are differences enough in regard to their external appearance; but these differences are by no means the whole or even the most important of the differences which obtain between these birds. There is hardly a single point of their structure which has not become more or less altered; and to give you an idea of how extensive these alterations are, I have here some very good skeletons, for which I am indebted to my friend, Mr. Tegetmeier, a great authority in these matters; by means of which, if you examine them by-and-by, you will be able to see the enormous difference in their bony structures. I had the privilege, some time ago, of access to some important MSS. of Mr. Darwin, who, I may tell you, has taken very great pains and spent much valuable time and attention on the investigation of these variations, and getting together all the facts that bear upon them. I obtained from these MSS. the following summary of the differences between the domestic breeds of pigeons; that is to say, a notification of the various points in which their organization differs. In the first place, the back of the skull may differ a good deal, and the development of the bones of the face may vary a great deal; the back varies a good deal; the shape of the lower jaw varies; the tongue varies very greatly, not only in correlation to the length and size of the beak, but it seems also to have a kind of independent variation of its own. Then the amount of naked skin round the eyes, and at the base of the beak, may vary enormously; so may the length of the eyelids, the shape of the nostrils, and the length of the neck. I have already noticed the habit of blowing out the gullet, so remarkable in the Pouter, and comparatively so in the others. There are great differences, too, in the size of the female and the male, the shape of the body, the number and width of the processes of the ribs, the development of the ribs, and the size, shape, and development of the breastbone. We may notice, too,--and I mention the fact because it has been disputed by what is assumed to be high authority,--the variation in the number of the sacral vertebrae. The number of these varies from eleven to fourteen, and that without any diminution in the number of the vertebrae of the back or of the tail. Then the number and position of the tail-feathers may vary enormously, and so may the number of the primary and secondary feathers of the wings. Again, the length of the feet and of the beak,--although they have no relation to each other, yet appear to go together,--that is, you have a long beak wherever you have long feet. There are differences also in the periods of the acquirement of the perfect plumage,--the size and shape of the eggs,--the nature of flight, and the powers of flight,--so-called "homing" birds having enormous flying powers; [1] while, on the other hand, the little Tumbler is so called because of its extraordinary faculty of turning head over heels in the air, instead of pursuing a direct course. And, lastly, the dispositions and voices of the birds may vary. Thus the case of the pigeons shows you that there is hardly a single particular,--whether of instinct, or habit, or bony structure, or of plumage,--of either the internal economy or the external shape, in which some variation or change may not take place, which, by selective breeding, may become perpetuated, and form the foundation of, and give rise to, a new race. [Footnote 1: The "Carrier," I learn from Mr. Tegetmeier, does not 'carry'; a high-bred bird of this breed being but a poor flier. The birds which fly long distances, and come home,--"homing" birds,--and are consequently used as carriers, are not "carriers" in the fancy sense.] If you carry in your mind's eye these four varieties of pigeons, you will bear with you as good a notion as you can have, perhaps, of the enormous extent to which a deviation from a primitive type may be carried by means of this process of selective breeding. 
2925	----	THE CONDITIONS OF EXISTENCE AS AFFECTING THE PERPETUATION OF LIVING BEINGS Lecture V. (of VI.), Lectures To Working Men, at the Museum of Practical Geology, 1863, On Darwin's work: "Origin of Species". By Thomas H. Huxley IN the last Lecture I endeavoured to prove to you that, while, as a general rule, organic beings tend to reproduce their kind, there is in them, also, a constantly recurring tendency to vary--to vary to a greater or to a less extent. Such a variety, I pointed out to you, might arise from causes which we do not understand; we therefore called it spontaneous; and it might come into existence as a definite and marked thing, without any gradations between itself and the form which preceded it. I further pointed out, that such a variety having once arisen, might be perpetuated to some extent, and indeed to a very marked extent, without any direct interference, or without any exercise of that process which we called selection. And then I stated further, that by such selection, when exercised artificially--if you took care to breed only from those forms which presented the same peculiarities of any variety which had arisen in this manner--the variation might be perpetuated, as far as we can see, indefinitely. The next question, and it is an important one for us, is this: Is there any limit to the amount of variation from the primitive stock which can be produced by this process of selective breeding? In considering this question, it will be useful to class the characteristics, in respect of which organic beings vary, under two heads: we may consider structural characteristics, and we may consider physiological characteristics. In the first place, as regards structural characteristics, I endeavoured to show you, by the skeletons which I had upon the table, and by reference to a great many well-ascertained facts, that the different breeds of Pigeons, the Carriers, Pouters, and Tumblers, might vary in any of their internal and important structural characters to a very great degree; not only might there be changes in the proportions of the skull, and the characters of the feet and beaks, and so on; but that there might be an absolute difference in the number of the vertebrae of the back, as in the sacral vertebrae of the Pouter; and so great is the extent of the variation in these and similar characters that I pointed out to you, by reference to the skeletons and the diagrams, that these extreme varieties may absolutely differ more from one another in their structural characters than do what naturalists call distinct SPECIES of pigeons; that is to say, that they differ so much in structure that there is a greater difference between the Pouter and the Tumbler than there is between such wild and distinct forms as the Rock Pigeon or the Ring Pigeon, or the Ring Pigeon and the Stock Dove; and indeed the differences are of greater value than this, for the structural differences between these domesticated pigeons are such as would be admitted by a naturalist, supposing he knew nothing at all about their origin, to entitle them to constitute even distinct genera. As I have used this term SPECIES, and shall probably use it a good deal, I had better perhaps devote a word or two to explaining what I mean by it. Animals and plants are divided into groups, which become gradually smaller, beginning with a KINGDOM, which is divided into SUB-KINGDOMS; then come the smaller divisions called PROVINCES; and so on from a PROVINCE to a CLASS from a CLASS to an ORDER, from ORDERS to FAMILIES, and from these to GENERA, until we come at length to the smallest groups of animals which can be defined one from the other by constant characters, which are not sexual; and these are what naturalists call SPECIES in practice, whatever they may do in theory. If, in a state of nature, you find any two groups of living beings, which are separated one from the other by some constantly-recurring characteristic, I don't care how slight and trivial, so long as it is defined and constant, and does not depend on sexual peculiarities, then all naturalists agree in calling them two species; that is what is meant by the use of the word species--that is to say, it is, for the practical naturalist, a mere question of structural differences. [1] We have seen now--to repeat this point once more, and it is very essential that we should rightly understand it--we have seen that breeds, known to have been derived from a common stock by selection, may be as different in their structure from the original stock as species may be distinct from each other. But is the like true of the physiological characteristics of animals? Do the physiological differences of varieties amount in degree to those observed between forms which naturalists call distinct species? This is a most important point for us to consider. As regards the great majority of physiological characteristics, there is no doubt that they are capable of being developed, increased, and modified by selection. There is no doubt that breeds may be made as different as species in many physiological characters. I have already pointed out to you very briefly the different habits of the breeds of Pigeons, all of which depend upon their physiological peculiarities,--as the peculiar habit of tumbling, in the Tumbler--the peculiarities of flight, in the "homing" birds,--the strange habit of spreading out the tail, and walking in a peculiar fashion, in the Fantail,--and, lastly, the habit of blowing out the gullet, so characteristic of the Pouter. These are all due to physiological modifications, and in all these respects these birds differ as much from each other as any two ordinary species do. So with Dogs in their habits and instincts. It is a physiological peculiarity which leads the Greyhound to chase its prey by sight,--that enables the Beagle to track it by the scent,--that impels the Terrier to its rat-hunting propensity,--and that leads the Retriever to its habit of retrieving. These habits and instincts are all the results of physiological differences and peculiarities, which have been developed from a common stock, at least there is every reason to believe so. But it is a most singular circumstance, that while you may run through almost the whole series of physiological processes, without finding a check to your argument, you come at last to a point where you do find a check, and that is in the reproductive processes. For there is a most singular circumstance in respect to natural species--at least about some of them--and it would be sufficient for the purposes of this argument if it were true of only one of them, but there is, in fact, a great number of such cases--and that is, that, similar as they may appear to be to mere races or breeds, they present a marked peculiarity in the reproductive process. If you breed from the male and female of the same race, you of course have offspring of the like kind, and if you make the offspring breed together, you obtain the same result, and if you breed from these again, you will still have the same kind of offspring; there is no check. But if you take members of two distinct species, however similar they may be to each other and make them breed together, you will find a check, with some modifications and exceptions, however, which I shall speak of presently. If you cross two such species with each other, then,--although you may get offspring in the case of the first cross, yet, if you attempt to breed from the products of that crossing, which are what are called HYBRIDS--that is, if you couple a male and a female hybrid--then the result is that in ninety-nine cases out of a hundred you will get no offspring at all; there will be no result whatsoever. The reason of this is quite obvious in some cases; the male hybrids, although possessing all the external appearances and characteristics of perfect animals, are physiologically imperfect and deficient in the structural parts of the reproductive elements necessary to generation. It is said to be invariably the case with the male mule, the cross between the Ass and the Mare; and hence it is, that, although crossing the Horse with the Ass is easy enough, and is constantly done, as far as I am aware, if you take two mules, a male and a female, and endeavour to breed from them, you get no offspring whatever; no generation will take place. This is what is called the sterility of the hybrids between two distinct species. You see that this is a very extraordinary circumstance; one does not see why it should be. The common teleological explanation is, that it is to prevent the impurity of the blood resulting from the crossing of one species with another, but you see it does not in reality do anything of the kind. There is nothing in this fact that hybrids cannot breed with each other, to establish such a theory; there is nothing to prevent the Horse breeding with the Ass, or the Ass with the Horse. So that this explanation breaks down, as a great many explanations of this kind do, that are only founded on mere assumptions. Thus you see that there is a great difference between "mongrels," which are crosses between distinct races, and "hybrids," which are crosses between distinct species. The mongrels are, so far as we know, fertile with one another. But between species, in many cases, you cannot succeed in obtaining even the first cross: at any rate it is quite certain that the hybrids are often absolutely infertile one with another. Here is a feature, then, great or small as it may be, which distinguishes natural species of animals. Can we find any approximation to this in the different races known to be produced by selective breeding from a common stock? Up to the present time the answer to that question is absolutely a negative one. As far as we know at present, there is nothing approximating to this check. In crossing the breeds between the Fantail and the Pouter, the Carrier and the Tumbler, or any other variety or race you may name--so far as we know at present--there is no difficulty in breeding together the mongrels. Take the Carrier and the Fantail, for instance, and let them represent the Horse and the Ass in the case of distinct species; then you have, as the result of their breeding, the Carrier-Fantail mongrel,--we will say the male and female mongrel,--and, as far as we know, these two when crossed would not be less fertile than the original cross, or than Carrier with Carrier. Here, you see, is a physiological contrast between the races produced by selective modification and natural species. I shall inquire into the value of this fact, and of some modifying circumstances by and by; for the present I merely put it broadly before you. But while considering this question of the limitations of species, a word must be said about what is called RECURRENCE--the tendency of races which have been developed by selective breeding from varieties to return to their primitive type. This is supposed by many to put an absolute limit to the extent of selective and all other variations. People say, "It is all very well to talk about producing these different races, but you know very well that if you turned all these birds wild, these Pouters, and Carriers, and so on, they would all return to their primitive stock." This is very commonly assumed to be a fact, and it is an argument that is commonly brought forward as conclusive; but if you will take the trouble to inquire into it rather closely, I think you will find that it is not worth very much. The first question of course is, Do they thus return to the primitive stock? And commonly as the thing is assumed and accepted, it is extremely difficult to get anything like good evidence of it. It is constantly said, for example, that if domesticated Horses are turned wild, as they have been in some parts of Asia Minor and South America, that they return at once to the primitive stock from which they were bred. But the first answer that you make to this assumption is, to ask who knows what the primitive stock was; and the second answer is, that in that case the wild Horses of Asia Minor ought to be exactly like the wild Horses of South America. If they are both like the same thing, they ought manifestly to be like each other! The best authorities, however, tell you that it is quite different. The wild Horse of Asia is said to be of a dun colour, with a largish head, and a great many other peculiarities; while the best authorities on the wild Horses of South America tell you that there is no similarity between their wild Horses and those of Asia Minor; the cut of their heads is very different, and they are commonly chestnut or bay-coloured. It is quite clear, therefore, that as by these facts there ought to have been two primitive stocks, they go for nothing in support of the assumption that races recur to one primitive stock, and so far as this evidence is concerned, it falls to the ground. Suppose for a moment that it were so, and that domesticated races, when turned wild, did return to some common condition, I cannot see that this would prove much more than that similar conditions are likely to produce similar results; and that when you take back domesticated animals into what we call natural conditions, you do exactly the same thing as if you carefully undid all the work you had gone through, for the purpose of bringing the animal from its wild to its domesticated state. I do not see anything very wonderful in the fact, if it took all that trouble to get it from a wild state, that it should go back into its original state as soon as you removed the conditions which produced the variation to the domesticated form. There is an important fact, however, forcibly brought forward by Mr. Darwin, which has been noticed in connection with the breeding of domesticated pigeons; and it is, that however different these breeds of pigeons may be from each other, and we have already noticed the great differences in these breeds, that if, among any of those variations, you chance to have a blue pigeon turn up, it will be sure to have the black bars across the wings, which are characteristic of the original wild stock, the Rock Pigeon. Now, this is certainly a very remarkable circumstance; but I do not see myself how it tells very strongly either one way or the other. I think, in fact, that this argument in favour of recurrence to the primitive type might prove a great deal too much for those who so constantly bring it forward. For example, Mr. Darwin has very forcibly urged, that nothing is commoner than if you examine a dun horse--and I had an opportunity of verifying this illustration lately, while in the islands of the West Highlands, where there are a great many dun horses--to find that horse exhibit a long black stripe down his back, very often stripes on his shoulder, and very often stripes on his legs. I, myself, saw a pony of this description a short time ago, in a baker's cart, near Rothesay, in Bute: it had the long stripe down the back, and stripes on the shoulders and legs, just like those of the Ass, the Quagga, and the Zebra. Now, if we interpret the theory of recurrence as applied to this case, might it not be said that here was a case of a variation exhibiting the characters and conditions of an animal occupying something like an intermediate position between the Horse, the Ass, the Quagga, and the Zebra, and from which these had been developed? In the same way with regard even to Man. Every anatomist will tell you that there is nothing commoner, in dissecting the human body, than to meet with what are called muscular variations--that is, if you dissect two bodies very carefully, you will probably find that the modes of attachment and insertion of the muscles are not exactly the same in both, there being great peculiarities in the mode in which the muscles are arranged; and it is very singular, that in some dissections of the human body you will come upon arrangements of the muscles very similar indeed to the same parts in the Apes. Is the conclusion in that case to be, that this is like the black bars in the case of the Pigeon, and that it indicates a recurrence to the primitive type from which the animals have been probably developed? Truly, I think that the opponents of modification and variation had better leave the argument of recurrence alone, or it may prove altogether too strong for them. To sum up,--the evidence as far as we have gone is against the argument as to any limit to divergences, so far as structure is concerned; and in favour of a physiological limitation. By selective breeding we can produce structural divergences as great as those of species, but we cannot produce equal physiological divergences. For the present I leave the question there. Now, the next problem that lies before us--and it is an extremely important one--is this: Does this selective breeding occur in nature? Because, if there is no proof of it, all that I have been telling you goes for nothing in accounting for the origin of species. Are natural causes competent to play the part of selection in perpetuating varieties? Here we labour under very great difficulties. In the last lecture I had occasion to point out to you the extreme difficulty of obtaining evidence even of the first origin of those varieties which we know to have occurred in domesticated animals. I told you, that almost always the origin of these varieties is overlooked, so that I could only produce two of three cases, as that of Gratio Kelleia and of the Ancon sheep. People forget, or do not take notice of them until they come to have a prominence; and if that is true of artificial cases, under our own eyes, and in animals in our own care, how much more difficult it must be to have at first hand good evidence of the origin of varieties in nature! Indeed, I do not know that it is possible by direct evidence to prove the origin of a variety in nature, or to prove selective breeding; but I will tell you what we can prove--and this comes to the same thing--that varieties exist in nature within the limits of species, and, what is more, that when a variety has come into existence in nature, there are natural causes and conditions, which are amply competent to play the part of a selective breeder; and although that is not quite the evidence that one would like to have--though it is not direct testimony--yet it is exceeding good and exceedingly powerful evidence in its way. As to the first point, of varieties existing among natural species, I might appeal to the universal experience of every naturalist, and of any person who has ever turned any attention at all to the characteristics of plants and animals in a state of nature; but I may as well take a few definite cases, and I will begin with Man himself. I am one of those who believe that, at present, there is no evidence whatever for saying, that mankind sprang originally from any more than a single pair; I must say, that I cannot see any good ground whatever, or even any tenable sort of evidence, for believing that there is more than one species of Man. Nevertheless, as you know, just as there are numbers of varieties in animals, so there are remarkable varieties of men. I speak not merely of those broad and distinct variations which you see at a glance. Everybody, of course, knows the difference between a Negro and a white man, and can tell a Chinaman from an Englishman. They each have peculiar characteristics of colour and physiognomy; but you must recollect that the characters of these races go very far deeper--they extend to the bony structure, and to the characters of that most important of all organs to us--the brain; so that, among men belonging to different races, or even within the same race, one man shall have a brain a third, or half, or even seventy per cent. bigger than another; and if you take the whole range of human brains, you will find a variation in some cases of a hundred per cent. Apart from these variations in the size of the brain, the characters of the skull vary. Thus if I draw the figures of a Mongul and of a Negro head on the blackboard, in the case of the last the breadth would be about seven-tenths, and in the other it would be nine-tenths of the total length. So that you see there is abundant evidence of variation among men in their natural condition. And if you turn to other animals there is just the same thing. The fox, for example, which has a very large geographical distribution all over Europe, and parts of Asia, and on the American Continent, varies greatly. There are mostly large foxes in the North, and smaller ones in the South. In Germany alone, the foresters reckon some eight different sorts. Of the tiger, no one supposes that there is more than one species; they extend from the hottest parts of Bengal, into the dry, cold, bitter steppes of Siberia, into a latitude of 50 degrees,--so that they may even prey upon the reindeer. These tigers have exceedingly different characteristics, but still they all keep their general features, so that there is no doubt as to their being tigers. The Siberian tiger has a thick fur, a small mane, and a longitudinal stripe down the back, while the tigers of Java and Sumatra differ in many important respects from the tigers of Northern Asia. So lions vary; so birds vary; and so, if you go further back and lower down in creation, you find that fishes vary. In different streams, in the same country even, you will find the trout to be quite different to each other and easily recognisable by those who fish in the particular streams. There is the same differences in leeches; leech collectors can easily point out to you the differences and the peculiarities which you yourself would probably pass by; so with fresh-water mussels; so, in fact, with every animal you can mention. In plants there is the same kind of variation. Take such a case even as the common bramble. The botanists are all at war about it; some of them wanting to make out that there are many species of it, and others maintaining that they are but many varieties of one species; and they cannot settle to this day which is a species and which is a variety! So that there can be no doubt whatsoever that any plant and any animal may vary in nature; that varieties may arise in the way I have described,--as spontaneous varieties,--and that those varieties may be perpetuated in the same way that I have shown you spontaneous varieties are perpetuated; I say, therefore, that there can be no doubt as to the origin and perpetuation of varieties in nature. But the question now is:--Does selection take place in nature? is there anything like the operation of man in exercising selective breeding, taking place in nature? You will observe that, at present, I say nothing about species; I wish to confine myself to the consideration of the production of those natural races which everybody admits to exist. The question is, whether in nature there are causes competent to produce races, just in the same way as man is able to produce by selection, such races of animals as we have already noticed. When a variety has arisen, the CONDITIONS OF EXISTENCE are such as to exercise an influence which is exactly comparable to that of artificial selection. By Conditions of Existence I mean two things,--there are conditions which are furnished by the physical, the inorganic world, and there are conditions of existence which are furnished by the organic world. There is, in the first place, CLIMATE; under that head I include only temperature and the varied amount of moisture of particular places. In the next place there is what is technically called STATION, which means--given the climate, the particular kind of place in which an animal or a plant lives or grows; for example, the station of a fish is in the water, of a fresh-water fish in fresh water; the station of a marine fish is in the sea, and a marine animal may have a station higher or deeper. So again with land animals: the differences in their stations are those of different soils and neighbourhoods; some being best adapted to a calcareous, and others to an arenaceous soil. The third condition of existence is FOOD, by which I mean food in the broadest sense, the supply of the materials necessary to the existence of an organic being; in the case of a plant the inorganic matters, such as carbonic acid, water, ammonia, and the earthy salts or salines; in the case of the animal the inorganic and organic matters, which we have seen they require; then these are all, at least the two first, what we may call the inorganic or physical conditions of existence. Food takes a mid-place, and then come the organic conditions; by which I mean the conditions which depend upon the state of the rest of the organic creation, upon the number and kind of living beings, with which an animal is surrounded. You may class these under two heads: there are organic beings, which operate as 'opponents', and there are organic beings which operate as 'helpers' to any given organic creature. The opponents may be of two kinds: there are the 'indirect opponents', which are what we may call 'rivals'; and there are the 'direct opponents', those which strive to destroy the creature; and these we call 'enemies'. By rivals I mean, of course, in the case of plants, those which require for their support the same kind of soil and station, and, among animals, those which require the same kind of station, or food, or climate; those are the indirect opponents; the direct opponents are, of course, those which prey upon an animal or vegetable. The 'helpers' may also be regarded as direct and indirect: in the case of a carnivorous animal, for example, a particular herbaceous plant may in multiplying be an indirect helper, by enabling the herbivora on which the carnivore preys to get more food, and thus to nourish the carnivore more abundantly; the direct helper may be best illustrated by reference to some parasitic creature, such as the tape-worm. The tape-worm exists in the human intestines, so that the fewer there are of men the fewer there will be of tape-worms, other things being alike. It is a humiliating reflection, perhaps, that we may be classed as direct helpers to the tape-worm, but the fact is so: we can all see that if there were no men there would be no tape-worms. It is extremely difficult to estimate, in a proper way, the importance and the working of the Conditions of Existence. I do not think there were any of us who had the remotest notion of properly estimating them until the publication of Mr. Darwin's work, which has placed them before us with remarkable clearness; and I must endeavour, as far as I can in my own fashion, to give you some notion of how they work. We shall find it easiest to take a simple case, and one as free as possible from every kind of complication. I will suppose, therefore, that all the habitable part of this globe--the dry land, amounting to about 51,000,000 square miles,--I will suppose that the whole of that dry land has the same climate, and that it is composed of the same kind of rock or soil, so that there will be the same station everywhere; we thus get rid of the peculiar influence of different climates and stations. I will then imagine that there shall be but one organic being in the world, and that shall be a plant. In this we start fair. Its food is to be carbonic acid, water and ammonia, and the saline matters in the soil, which are, by the supposition, everywhere alike. We take one single plant, with no opponents, no helpers, and no rivals; it is to be a "fair field, and no favour". Now, I will ask you to imagine further that it shall be a plant which shall produce every year fifty seeds, which is a very moderate number for a plant to produce; and that, by the action of the winds and currents, these seeds shall be equally and gradually distributed over the whole surface of the land. I want you now to trace out what will occur, and you will observe that I am not talking fallaciously any more than a mathematician does when he expounds his problem. If you show that the conditions of your problem are such as may actually occur in nature and do not transgress any of the known laws of nature in working out your proposition, then you are as safe in the conclusion you arrive at as is the mathematician in arriving at the solution of his problem. In science, the only way of getting rid of the complications with which a subject of this kind is environed, is to work in this deductive method. What will be the result, then? I will suppose that every plant requires one square foot of ground to live upon; and the result will be that, in the course of nine years, the plant will have occupied every single available spot in the whole globe! I have chalked upon the blackboard the figures by which I arrive at the result:-- Plants. Plants 1 x 50 in 1st year = 50 50 x 50 " 2nd " = 2,500 2,500 x 50 " 3rd " = 125,000 125,000 x 50 " 4th " = 6,250,000 6,250,000 x 50 " 5th " = 312,500,000 312,500,000 x 50 " 6th " = 15,625,000,000 15,625,000,000 x 50 " 7th " = 781,250,000,000 781,250,000,000 x 50 " 8th " = 39,062,500,000,000 39,062,500,000,000 x 50& " 9th " = 1,953,125,000,000,000 51,000,000 sq. miles--the dry surface of the earth x 27,878,400--the number of sq. ft. in 1 sq. mile = sq. ft. 1,421,798,400,000,000 being 531,326,600,000,000 square feet less than would be required at the end of the ninth year. You will see from this that, at the end of the first year the single plant will have produced fifty more of its kind; by the end of the second year these will have increased to 2,500; and so on, in succeeding years, you get beyond even trillions; and I am not at all sure that I could tell you what the proper arithmetical denomination of the total number really is; but, at any rate, you will understand the meaning of all those noughts. Then you see that, at the bottom, I have taken the 51,000,000 of square miles, constituting the surface of the dry land; and as the number of square feet are placed under and subtracted from the number of seeds that would be produced in the ninth year, you can see at once that there would be an immense number more of plants than there would be square feet of ground for their accommodation. This is certainly quite enough to prove my point; that between the eighth and ninth year after being planted the single plant would have stocked the whole available surface of the earth. This is a thing which is hardly conceivable--it seems hardly imaginable--yet it is so. It is indeed simply the law of Malthus exemplified. Mr. Malthus was a clergyman, who worked out this subject most minutely and truthfully some years ago; he showed quite clearly,--and although he was much abused for his conclusions at the time, they have never yet been disproved and never will be--he showed that in consequence of the increase in the number of organic beings in a geometrical ratio, while the means of existence cannot be made to increase in the same ratio, that there must come a time when the number of organic beings will be in excess of the power of production of nutriment, and that thus some check must arise to the further increase of those organic beings. At the end of the ninth year we have seen that each plant would not be able to get its full square foot of ground, and at the end of another year it would have to share that space with fifty others the produce of the seeds which it would give off. What, then, takes place? Every plant grows up, flourishes, occupies its square foot of ground, and gives off its fifty seeds; but notice this, that out of this number only one can come to anything; there is thus, as it were, forty-nine chances to one against its growing up; it depends upon the most fortuitous circumstances whether any one of these fifty seeds shall grow up and flourish, or whether it shall die and perish. This is what Mr. Darwin has drawn attention to, and called the "STRUGGLE FOR EXISTENCE"; and I have taken this simple case of a plant because some people imagine that the phrase seems to imply a sort of fight. I have taken this plant and shown you that this is the result of the ratio of the increase, the necessary result of the arrival of a time coming for every species when exactly as many members must be destroyed as are born; that is the inevitable ultimate result of the rate of production. Now, what is the result of all this? I have said that there are forty-nine struggling against every one; and it amounts to this, that the smallest possible start given to any one seed may give it an advantage which will enable it to get ahead of all the others; anything that will enable any one of these seeds to germinate six hours before any of the others will, other things being alike, enable it to choke them out altogether. I have shown you that there is no particular in which plants will not vary from each other; it is quite possible that one of our imaginary plants may vary in such a character as the thickness of the integument of its seeds; it might happen that one of the plants might produce seeds having a thinner integument, and that would enable the seeds of that plant to germinate a little quicker than those of any of the others, and those seeds would most inevitably extinguish the forty-nine times as many that were struggling with them. I have put it in this way, but you see the practical result of the process is the same as if some person had nurtured the one and destroyed the other seeds. It does not matter how the variation is produced, so long as it is once allowed to occur. The variation in the plant once fairly started tends to become hereditary and reproduce itself; the seeds would spread themselves in the same way and take part in the struggle with the forty-nine hundred, or forty-nine thousand, with which they might be exposed. Thus, by degrees, this variety, with some slight organic change or modification, must spread itself over the whole surface of the habitable globe, and extirpate or replace the other kinds. That is what is meant by NATURAL SELECTION; that is the kind of argument by which it is perfectly demonstrable that the conditions of existence may play exactly the same part for natural varieties as man does for domesticated varieties. No one doubts at all that particular circumstances may be more favourable for one plant and less so for another, and the moment you admit that, you admit the selective power of nature. Now, although I have been putting a hypothetical case, you must not suppose that I have been reasoning hypothetically. There are plenty of direct experiments which bear out what we may call the theory of natural selection; there is extremely good authority for the statement that if you take the seed of mixed varieties of wheat and sow it, collecting the seed next year and sowing it again, at length you will find that out of all your varieties only two or three have lived, or perhaps even only one. There were one or two varieties which were best fitted to get on, and they have killed out the other kinds in just the same way and with just the same certainty as if you had taken the trouble to remove them. As I have already said, the operation of nature is exactly the same as the artificial operation of man. But if this be true of that simple case, which I put before you, where there is nothing but the rivalry of one member of a species with others, what must be the operation of selective conditions, when you recollect as a matter of fact, that for every species of animal or plant there are fifty or a hundred species which might all, more or less, be comprehended in the same climate, food, and station;--that every plant has multitudinous animals which prey upon it, and which are its direct opponents; and that these have other animals preying upon them,--that every plant has its indirect helpers in the birds that scatter abroad its seed, and the animals that manure it with their dung;--I say, when these things are considered, it seems impossible that any variation which may arise in a species in nature should not tend in some way or other either to be a little better or worse than the previous stock; if it is a little better it will have an advantage over and tend to extirpate the latter in this crush and struggle; and if it is a little worse it will itself be extirpated. I know nothing that more appropriately expresses this, than the phrase, "the struggle for existence"; because it brings before your minds, in a vivid sort of way, some of the simplest possible circumstances connected with it. When a struggle is intense there must be some who are sure to be trodden down, crushed, and overpowered by others; and there will be some who just manage to get through only by the help of the slightest accident. I recollect reading an account of the famous retreat of the French troops, under Napoleon, from Moscow. Worn out, tired, and dejected, they at length came to a great river over which there was but one bridge for the passage of the vast army. Disorganised and demoralised as that army was, the struggle must certainly have been a terrible one--every one heeding only himself, and crushing through the ranks and treading down his fellows. The writer of the narrative, who was himself one of those who were fortunate enough to succeed in getting over, and not among the thousands who were left behind or forced into the river, ascribed his escape to the fact that he saw striding onward through the mass a great strong fellow,--one of the French Cuirassiers, who had on a large blue cloak--and he had enough presence of mind to catch and retain a hold of this strong man's cloak. He says, "I caught hold of his cloak, and although he swore at me and cut at and struck me by turns, and at last, when he found he could not shake me off, fell to entreating me to leave go or I should prevent him from escaping, besides not assisting myself, I still kept tight hold of him, and would not quit my grasp until he had at last dragged me through." Here you see was a case of selective saving--if we may so term it--depending for its success on the strength of the cloth of the Cuirassier's cloak. It is the same in nature; every species has its bridge of Beresina; it has to fight its way through and struggle with other species; and when well nigh overpowered, it may be that the smallest chance, something in its colour, perhaps--the minutest circumstance--will turn the scale one way or the other. Suppose that by a variation of the black race it had produced the white man at any time--you know that the Negroes are said to believe this to have been the case, and to imagine that Cain was the first white man, and that we are his descendants--suppose that this had ever happened, and that the first residence of this human being was on the West Coast of Africa. There is no great structural difference between the white man and the Negro, and yet there is something so singularly different in the constitution of the two, that the malarias of that country, which do not hurt the black at all, cut off and destroy the white. Then you see there would have been a selective operation performed; if the white man had risen in that way, he would have been selected out and removed by means of the malaria. Now there really is a very curious case of selection of this sort among pigs, and it is a case of selection of colour too. In the woods of Florida there are a great many pigs, and it is a very curious thing that they are all black, every one of them. Professor Wyman was there some years ago, and on noticing no pigs but these black ones, he asked some of the people how it was that they had no white pigs, and the reply was that in the woods of Florida there was a root which they called the Paint Root, and that if the white pigs were to eat any of it, it had the effect of making their hoofs crack, and they died, but if the black pigs eat any of it, it did not hurt them at all. Here was a very simple case of natural selection. A skilful breeder could not more carefully develope the black breed of pigs, and weed out all the white pigs, than the Paint Root does. To show you how remarkably indirect may be such natural selective agencies as I have referred to, I will conclude by noticing a case mentioned by Mr. Darwin, and which is certainly one of the most curious of its kind. It is that of the Humble Bee. It has been noticed that there are a great many more humble bees in the neighbourhood of towns, than out in the open country; and the explanation of the matter is this: the humble bees build nests, in which they store their honey and deposit the larvae and eggs. The field mice are amazingly fond of the honey and larvae; therefore, wherever there are plenty of field mice, as in the country, the humble bees are kept down; but in the neighbourhood of towns, the number of cats which prowl about the fields eat up the field mice, and of course the more mice they eat up the less there are to prey upon the larvae of the bees--the cats are therefore the INDIRECT HELPERS of the bees! [2] Coming back a step farther we may say that the old maids are also indirect friends of the humble bees, and indirect enemies of the field mice, as they keep the cats which eat up the latter! This is an illustration somewhat beneath the dignity of the subject, perhaps, but it occurs to me in passing, and with it I will conclude this lecture. [Footnote 1: I lay stress here on the 'practical' signification of "Species." Whether a physiological test between species exist or not, it is hardly ever applicable by the practical naturalist.] [Footnote 2: The humble bees, on the other hand, are direct helpers of some plants, such as the heartsease and red clover, which are fertilized by the visits of the bees; and they are indirect helpers of the numerous insects which are more or less completely supported by the heartsease and red clover.] 
2926	----	A CRITICAL EXAMINATION OF THE POSITION OF MR. DARWIN'S WORK, "ON THE ORIGIN OF SPECIES," IN RELATION TO THE COMPLETE THEORY OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE By Thomas H. Huxley IN the preceding five lectures I have endeavoured to give you an account of those facts, and of those reasonings from facts, which form the data upon which all theories regarding the causes of the phenomena of organic nature must be based. And, although I have had frequent occasion to quote Mr. Darwin--as all persons hereafter, in speaking upon these subjects, will have occasion to quote his famous book on the "Origin of Species,"--you must yet remember that, wherever I have quoted him, it has not been upon theoretical points, or for statements in any way connected with his particular speculations, but on matters of fact, brought forward by himself, or collected by himself, and which appear incidentally in his book. If a man 'will' make a book, professing to discuss a single question, an encyclopaedia, I cannot help it. Now, having had an opportunity of considering in this sort of way the different statements bearing upon all theories whatsoever, I have to lay before you, as fairly as I can, what is Mr. Darwin's view of the matter and what position his theories hold, when judged by the principles which I have previously laid down, as deciding our judgments upon all theories and hypotheses. I have already stated to you that the inquiry respecting the causes of the phenomena of organic nature resolves itself into two problems--the first being the question of the origination of living or organic beings; and the second being the totally distinct problem of the modification and perpetuation of organic beings when they have already come into existence. The first question Mr. Darwin does not touch; he does not deal with it at all; but he says--given the origin of organic matter--supposing its creation to have already taken place, my object is to show in consequence of what laws and what demonstrable properties of organic matter, and of its environments, such states of organic nature as those with which we are acquainted must have come about. This, you will observe, is a perfectly legitimate proposition; every person has a right to define the limits of the inquiry which he sets before himself; and yet it is a most singular thing that in all the multifarious, and, not unfrequently, ignorant attacks which have been made upon the 'Origin of Species', there is nothing which has been more speciously criticised than this particular limitation. If people have nothing else to urge against the book, they say--"Well, after all, you see, Mr. Darwin's explanation of the 'Origin of Species' is not good for much, because, in the long run, he admits that he does not know how organic matter began to exist. But if you admit any special creation for the first particle of organic matter you may just as well admit it for all the rest; five hundred or five thousand distinct creations are just as intelligible, and just as little difficult to understand, as one." The answer to these cavils is two-fold. In the first place, all human inquiry must stop somewhere; all our knowledge and all our investigation cannot take us beyond the limits set by the finite and restricted character of our faculties, or destroy the endless unknown, which accompanies, like its shadow, the endless procession of phenomena. So far as I can venture to offer an opinion on such a matter, the purpose of our being in existence, the highest object that human beings can set before themselves, is not the pursuit of any such chimera as the annihilation of the unknown; but it is simply the unwearied endeavour to remove its boundaries a little further from our little sphere of action. I wonder if any historian would for a moment admit the objection, that it is preposterous to trouble ourselves about the history of the Roman Empire, because we do not know anything positive about the origin and first building of the city of Rome! Would it be a fair objection to urge, respecting the sublime discoveries of a Newton, or a Kepler, those great philosophers, whose discoveries have been of the profoundest benefit and service to all men,--to say to them--"After all that you have told us as to how the planets revolve, and how they are maintained in their orbits, you cannot tell us what is the cause of the origin of the sun, moon, and stars. So what is the use of what you have done?" Yet these objections would not be one whit more preposterous than the objections which have been made to the 'Origin of Species.' Mr. Darwin, then, had a perfect right to limit his inquiry as he pleased, and the only question for us--the inquiry being so limited--is to ascertain whether the method of his inquiry is sound or unsound; whether he has obeyed the canons which must guide and govern all investigation, or whether he has broken them; and it was because our inquiry this evening is essentially limited to that question, that I spent a good deal of time in a former lecture (which, perhaps, some of you thought might have been better employed), in endeavouring to illustrate the method and nature of scientific inquiry in general. We shall now have to put in practice the principles that I then laid down. I stated to you in substance, if not in words, that wherever there are complex masses of phenomena to be inquired into, whether they be phenomena of the affairs of daily life, or whether they belong to the more abstruse and difficult problems laid before the philosopher, our course of proceeding in unravelling that complex chain of phenomena with a view to get at its cause, is always the same; in all cases we must invent an hypothesis; we must place before ourselves some more or less likely supposition respecting that cause; and then, having assumed an hypothesis, having supposed cause for the phenomena in question, we must endeavour, on the one hand, to demonstrate our hypothesis, or, on the other, to upset and reject it altogether, by testing it in three ways. We must, in the first place, be prepared to prove that the supposed causes of the phenomena exist in nature; that they are what the logicians call 'vera causae'--true causes;--in the next place, we should be prepared to show that the assumed causes of the phenomena are competent to produce such phenomena as those which we wish to explain by them; and in the last place, we ought to be able to show that no other known causes are competent to produce those phenomena. If we can succeed in satisfying these three conditions we shall have demonstrated our hypothesis; or rather I ought to say we shall have proved it as far as certainty is possible for us; for, after all, there is no one of our surest convictions which may not be upset, or at any rate modified by a further accession of knowledge. It was because it satisfied these conditions that we accepted the hypothesis as to the disappearance of the tea-pot and spoons in the case I supposed in a previous lecture; we found that our hypothesis on that subject was tenable and valid, because the supposed cause existed in nature, because it was competent to account for the phenomena, and because no other known cause was competent to account for them; and it is upon similar grounds that any hypothesis you choose to name is accepted in science as tenable and valid. What is Mr. Darwin's hypothesis? As I apprehend it--for I have put it into a shape more convenient for common purposes than I could find 'verbatim' in his book--as I apprehend it, I say, it is, that all the phenomena of organic nature, past and present, result from, or are caused by, the inter-action of those properties of organic matter, which we have called ATAVISM and VARIABILITY, with the CONDITIONS OF EXISTENCE; or, in other words,--given the existence of organic matter, its tendency to transmit its properties, and its tendency occasionally to vary; and, lastly, given the conditions of existence by which organic matter is surrounded--that these put together are the causes of the Present and of the Past conditions of ORGANIC NATURE. Such is the hypothesis as I understand it. Now let us see how it will stand the various tests which I laid down just now. In the first place, do these supposed causes of the phenomena exist in nature? Is it the fact that in nature these properties of organic matter--atavism and variability--and those phenomena which we have called the conditions of existence,--is it true that they exist? Well, of course, if they do not exist, all that I have told you in the last three or four lectures must be incorrect, because I have been attempting to prove that they do exist, and I take it that there is abundant evidence that they do exist; so far, therefore, the hypothesis does not break down. But in the next place comes a much more difficult inquiry:--Are the causes indicated competent to give rise to the phenomena of organic nature? I suspect that this is indubitable to a certain extent. It is demonstrable, I think, as I have endeavoured to show you, that they are perfectly competent to give rise to all the phenomena which are exhibited by RACES in nature. Furthermore, I believe that they are quite competent to account for all that we may call purely structural phenomena which are exhibited by SPECIES in nature. On that point also I have already enlarged somewhat. Again, I think that the causes assumed are competent to account for most of the physiological characteristics of species, and I not only think that they are competent to account for them, but I think that they account for many things which otherwise remain wholly unaccountable and inexplicable, and I may say incomprehensible. For a full exposition of the grounds on which this conviction is based, I must refer you to Mr. Darwin's work; all that I can do now is to illustrate what I have said by two or three cases taken almost at random. I drew your attention, on a previous evening, to the facts which are embodied in our systems of Classification, which are the results of the examination and comparison of the different members of the animal kingdom one with another. I mentioned that the whole of the animal kingdom is divisible into five sub-kingdoms; that each of these sub-kingdoms is again divisible into provinces; that each province may be divided into classes, and the classes into the successively smaller groups, orders, families, genera, and species. Now, in each of these groups, the resemblance in structure among the members of the group is closer in proportion as the group is smaller. Thus, a man and a worm are members of the animal kingdom in virtue of certain apparently slight though really fundamental resemblances which they present. But a man and a fish are members of the same sub-kingdom 'Vertebrata', because they are much more like one another than either of them is to a worm, or a snail, or any member of the other sub-kingdoms. For similar reasons men and horses are arranged as members of the same Class, 'Mammalia'; men and apes as members of the same Order, 'Primates'; and if there were any animals more like men than they were like any of the apes, and yet different from men in important and constant particulars of their organization, we should rank them as members of the same Family, or of the same Genus, but as of distinct Species. That it is possible to arrange all the varied forms of animals into groups, having this sort of singular subordination one to the other, is a very remarkable circumstance; but, as Mr. Darwin remarks, this is a result which is quite to be expected, if the principles which he lays down be correct. Take the case of the races which are known to be produced by the operation of atavism and variability, and the conditions of existence which check and modify these tendencies. Take the case of the pigeons that I brought before you; there it was shown that they might be all classed as belonging to some one of five principal divisions, and that within these divisions other subordinate groups might be formed. The members of these groups are related to one another in just the same way as the genera of a family, and the groups themselves as the families of an order, or the orders of a class; while all have the same sort of structural relations with the wild rock-pigeon, as the members of any great natural group have with a real or imaginary typical form. Now, we know that all varieties of pigeons of every kind have arisen by a process of selective breeding from a common stock, the rock-pigeon; hence, you see, that if all species of animals have proceeded from some common stock, the general character of their structural relations, and of our systems of classification, which express those relations, would be just what we find them to be. In other words, the hypothetical cause is, so far, competent to produce effects similar to those of the real cause. Take, again, another set of very remarkable facts,--the existence of what are called rudimentary organs, organs for which we can find no obvious use, in the particular animal economy in which they are found, and yet which are there. Such are the splint-like bones in the leg of the horse, which I here show you, and which correspond with bones which belong to certain toes and fingers in the human hand and foot. In the horse you see they are quite rudimentary, and bear neither toes nor fingers; so that the horse has only one "finger" in his fore-foot and one "toe" in his hind foot. But it is a very curious thing that the animals closely allied to the horse show more toes than he; as the rhinoceros, for instance: he has these extra toes well formed, and anatomical facts show very clearly that he is very closely related to the horse indeed. So we may say that animals, in an anatomical sense nearly related to the horse, have those parts which are rudimentary in him, fully developed. Again, the sheep and the cow have no cutting-teeth, but only a hard pad in the upper jaw. That is the common characteristic of ruminants in general. But the calf has in its upper jaw some rudiments of teeth which never are developed, and never play the part of teeth at all. Well, if you go back in time, you find some of the older, now extinct, allies of the ruminants have well-developed teeth in their upper jaws; and at the present day the pig (which is in structure closely connected with ruminants) has well-developed teeth in its upper jaw; so that here is another instance of organs well-developed and very useful, in one animal, represented by rudimentary organs, for which we can discover no purpose whatsoever, in another closely allied animal. The whalebone whale, again, has horny "whalebone" plates in its mouth, and no teeth; but the young foetal whale, before it is born, has teeth in its jaws; they, however, are never used, and they never come to anything. But other members of the group to which the whale belongs have well-developed teeth in both jaws. Upon any hypothesis of special creation, facts of this kind appear to me to be entirely unaccountable and inexplicable, but they cease to be so if you accept Mr. Darwin's hypothesis, and see reason for believing that the whalebone whale and the whale with teeth in its mouth both sprang from a whale that had teeth, and that the teeth of the foetal whale are merely remnants--recollections, if we may so say--of the extinct whale. So in the case of the horse and the rhinoceros: suppose that both have descended by modification from some earlier form which had the normal number of toes, and the persistence of the rudimentary bones which no longer support toes in the horse becomes comprehensible. In the language that we speak in England, and in the language of the Greeks, there are identical verbal roots, or elements entering into the composition of words. That fact remains unintelligible so long as we suppose English and Greek to be independently created tongues; but when it is shown that both languages are descended from one original, the Sanscrit, we give an explanation of that resemblance. In the same way the existence of identical structural roots, if I may so term them, entering into the composition of widely different animals, is striking evidence in favour of the descent of those animals from a common original. To turn to another kind of illustration:--If you regard the whole series of stratified rocks--that enormous thickness of sixty or seventy thousand feet that I have mentioned before, constituting the only record we have of a most prodigious lapse of time, that time being, in all probability, but a fraction of that of which we have no record;--if you observe in these successive strata of rocks successive groups of animals arising and dying out, a constant succession, giving you the same kind of impression, as you travel from one group of strata to another, as you would have in travelling from one country to another;--when you find this constant succession of forms, their traces obliterated except to the man of science,--when you look at this wonderful history, and ask what it means, it is only a paltering with words if you are offered the reply,--'They were so created.' But if, on the other hand, you look on all forms of organized beings as the results of the gradual modification of a primitive type, the facts receive a meaning, and you see that these older conditions are the necessary predecessors of the present. Viewed in this light the facts of palaeontology receive a meaning--upon any other hypothesis, I am unable to see, in the slightest degree, what knowledge or signification we are to draw out of them. Again, note as bearing upon the same point, the singular likeness which obtains between the successive Faunae and Florae, whose remains are preserved on the rocks: you never find any great and enormous difference between the immediately successive Faunae and Florae, unless you have reason to believe there has also been a great lapse of time or a great change of conditions. The animals, for instance, of the newest tertiary rocks, in any part of the world, are always, and without exception, found to be closely allied with those which now live in that part of the world. For example, in Europe, Asia, and Africa, the large mammals are at present rhinoceroses, hippopotamuses, elephants, lions, tigers, oxen, horses, etc.; and if you examine the newest tertiary deposits, which contain the animals and plants which immediately preceded those which now exist in the same country, you do not find gigantic specimens of ant-eaters and kangaroos, but you find rhinoceroses, elephants, lions, tigers, etc.,--of different species to those now living,--but still their close allies. If you turn to South America, where, at the present day, we have great sloths and armadilloes and creatures of that kind, what do you find in the newest tertiaries? You find the great sloth-like creature, the 'Megatherium', and the great armadillo, the 'Glyptodon', and so on. And if you go to Australia you find the same law holds good, namely, that that condition of organic nature which has preceded the one which now exists, presents differences perhaps of species, and of genera, but that the great types of organic structure are the same as those which now flourish. What meaning has this fact upon any other hypothesis or supposition than one of successive modification? But if the population of the world, in any age, is the result of the gradual modification of the forms which peopled it in the preceding age,--if that has been the case, it is intelligible enough; because we may expect that the creature that results from the modification of an elephantine mammal shall be something like an elephant, and the creature which is produced by the modification of an armadillo-like mammal shall be like an armadillo. Upon that supposition, I say, the facts are intelligible; upon any other, that I am aware of, they are not. So far, the facts of palaeontology are consistent with almost any form of the doctrine of progressive modification; they would not be absolutely inconsistent with the wild speculations of De Maillet, or with the less objectionable hypothesis of Lamarck. But Mr. Darwin's views have one peculiar merit; and that is, that they are perfectly consistent with an array of facts which are utterly inconsistent with and fatal to, any other hypothesis of progressive modification which has yet been advanced. It is one remarkable peculiarity of Mr. Darwin's hypothesis that it involves no necessary progression or incessant modification, and that it is perfectly consistent with the persistence for any length of time of a given primitive stock, contemporaneously with its modifications. To return to the case of the domestic breeds of pigeons, for example; you have the Dove-cot pigeon, which closely resembles the Rock pigeon, from which they all started, existing at the same time with the others. And if species are developed in the same way in nature, a primitive stock and its modifications may, occasionally, all find the conditions fitted for their existence; and though they come into competition, to a certain extent, with one another, the derivative species may not necessarily extirpate the primitive one, or 'vice versa'. Now palaeontology shows us many facts which are perfectly harmonious with these observed effects of the process by which Mr. Darwin supposes species to have originated, but which appear to me to be totally inconsistent with any other hypothesis which has been proposed. There are some groups of animals and plants, in the fossil world, which have been said to belong to "persistent types," because they have persisted, with very little change indeed, through a very great range of time, while everything about them has changed largely. There are families of fishes whose type of construction has persisted all the way from the carboniferous rock right up to the cretaceous; and others which have lasted through almost the whole range of the secondary rocks, and from the lias to the older tertiaries. It is something stupendous this--to consider a genus lasting without essential modifications through all this enormous lapse of time while almost everything else was changed and modified. Thus I have no doubt that Mr. Darwin's hypothesis will be found competent to explain the majority of the phenomena exhibited by species in nature; but in an earlier lecture I spoke cautiously with respect to its power of explaining all the physiological peculiarities of species. There is, in fact, one set of these peculiarities which the theory of selective modification, as it stands at present, is not wholly competent to explain, and that is the group of phenomena which I mentioned to you under the name of Hybridism, and which I explained to consist in the sterility of the offspring of certain species when crossed one with another. It matters not one whit whether this sterility is universal, or whether it exists only in a single case. Every hypothesis is bound to explain, or, at any rate, not be inconsistent with, the whole of the facts which it professes to account for; and if there is a single one of these facts which can be shown to be inconsistent with (I do not merely mean inexplicable by, but contrary to) the hypothesis, the hypothesis falls to the ground,--it is worth nothing. One fact with which it is positively inconsistent is worth as much, and as powerful in negativing the hypothesis, as five hundred. If I am right in thus defining the obligations of an hypothesis, Mr. Darwin, in order to place his views beyond the reach of all possible assault, ought to be able to demonstrate the possibility of developing from a particular stock by selective breeding, two forms, which should either be unable to cross one with another, or whose cross-bred offspring should be infertile with one another. For, you see, if you have not done that you have not strictly fulfilled all the conditions of the problem; you have not shown that you can produce, by the cause assumed, all the phenomena which you have in nature. Here are the phenomena of Hybridism staring you in the face, and you cannot say, 'I can, by selective modification, produce these same results.' Now, it is admitted on all hands that, at present, so far as experiments have gone, it has not been found possible to produce this complete physiological divergence by selective breeding. I stated this very clearly before, and I now refer to the point, because, if it could be proved, not only that this 'has' not been done, but that it 'cannot' be done; if it could be demonstrated that it is impossible to breed selectively, from any stock, a form which shall not breed with another, produced from the same stock; and if we were shown that this must be the necessary and inevitable results of all experiments, I hold that Mr. Darwin's hypothesis would be utterly shattered. But has this been done? or what is really the state of the case? It is simply that, so far as we have gone yet with our breeding, we have not produced from a common stock two breeds which are not more or less fertile with one another. I do not know that there is a single fact which would justify any one in saying that any degree of sterility has been observed between breeds absolutely known to have been produced by selective breeding from a common stock. On the other hand, I do not know that there is a single fact which can justify any one in asserting that such sterility cannot be produced by proper experimentation. For my own part, I see every reason to believe that it may, and will be so produced. For, as Mr. Darwin has very properly urged, when we consider the phenomena of sterility, we find they are most capricious; we do not know what it is that the sterility depends on. There are some animals which will not breed in captivity; whether it arises from the simple fact of their being shut up and deprived of their liberty, or not, we do not know, but they certainly will not breed. What an astounding thing this is, to find one of the most important of all functions annihilated by mere imprisonment! So, again, there are cases known of animals which have been thought by naturalists to be undoubted species, which have yielded perfectly fertile hybrids; while there are other species which present what everybody believes to be varieties [1] which are more or less infertile with one another. There are other cases which are truly extraordinary; there is one, for example, which has been carefully examined,--of two kinds of sea-weed, of which the male element of the one, which we may call A, fertilizes the female element of the other, B; while the male element of B will not fertilize the female element of A; so that, while the former experiment seems to show us that they are 'varieties', the latter leads to the conviction that they are 'species'. When we see how capricious and uncertain this sterility is, how unknown the conditions on which it depends, I say that we have no right to affirm that those conditions will not be better understood by and by, and we have no ground for supposing that we may not be able to experiment so as to obtain that crucial result which I mentioned just now. So that though Mr. Darwin's hypothesis does not completely extricate us from this difficulty at present, we have not the least right to say it will not do so. There is a wide gulf between the thing you cannot explain and the thing that upsets you altogether. There is hardly any hypothesis in this world which has not some fact in connection with it which has not been explained, but that is a very different affair to a fact that entirely opposes your hypothesis; in this case all you can say is, that your hypothesis is in the same position as a good many others. Now, as to the third test, that there are no other causes competent to explain the phenomena, I explained to you that one should be able to say of an hypothesis, that no other known causes than those supposed by it are competent to give rise to the phenomena. Here, I think, Mr. Darwin's view is pretty strong. I really believe that the alternative is either Darwinism or nothing, for I do not know of any rational conception or theory of the organic universe which has any scientific position at all beside Mr. Darwin's. I do not know of any proposition that has been put before us with the intention of explaining the phenomena of organic nature, which has in its favour a thousandth part of the evidence which may be adduced in favour of Mr. Darwin's views. Whatever may be the objections to his views, certainly all others are absolutely out of court. Take the Lamarckian hypothesis, for example. Lamarck was a great naturalist, and to a certain extent went the right way to work; he argued from what was undoubtedly a true cause of some of the phenomena of organic nature. He said it is a matter of experience that an animal may be modified more or less in consequence of its desires and consequent actions. Thus, if a man exercise himself as a blacksmith, his arms will become strong and muscular; such organic modification is a result of this particular action and exercise. Lamarck thought that by a very simple supposition based on this truth he could explain the origin of the various animal species: he said, for example, that the short-legged birds which live on fish had been converted into the long-legged waders by desiring to get the fish without wetting their bodies, and so stretching their legs more and more through successive generations. If Lamarck could have shown experimentally, that even races of animals could be produced in this way, there might have been some ground for his speculations. But he could show nothing of the kind, and his hypothesis has pretty well dropped into oblivion, as it deserved to do. I said in an earlier lecture that there are hypotheses and hypotheses, and when people tell you that Mr. Darwin's strongly-based hypothesis is nothing but a mere modification of Lamarck's, you will know what to think of their capacity for forming a judgment on this subject. But you must recollect that when I say I think it is either Mr. Darwin's hypothesis or nothing; that either we must take his view, or look upon the whole of organic nature as an enigma, the meaning of which is wholly hidden from us; you must understand that I mean that I accept it provisionally, in exactly the same way as I accept any other hypothesis. Men of science do not pledge themselves to creeds; they are bound by articles of no sort; there is not a single belief that it is not a bounden duty with them to hold with a light hand and to part with it cheerfully, the moment it is really proved to be contrary to any fact, great or small. And if, in course of time I see good reasons for such a proceeding, I shall have no hesitation in coming before you, and pointing out any change in my opinion without finding the slightest occasion to blush for so doing. So I say that we accept this view as we accept any other, so long as it will help us, and we feel bound to retain it only so long as it will serve our great purpose--the improvement of Man's estate and the widening of his knowledge. The moment this, or any other conception, ceases to be useful for these purposes, away with it to the four winds; we care not what becomes of it! But to say truth, although it has been my business to attend closely to the controversies roused by the publication of Mr. Darwin's book, I think that not one of the enormous mass of objections and obstacles which have been raised is of any very great value, except that sterility case which I brought before you just now. All the rest are misunderstandings of some sort, arising either from prejudice, or want of knowledge, or still more from want of patience and care in reading the work. For you must recollect that it is not a book to be read with as much ease as its pleasant style may lead you to imagine. You spin through it as if it were a novel the first time you read it, and think you know all about it; the second time you read it you think you know rather less about it; and the third time, you are amazed to find how little you have really apprehended its vast scope and objects. I can positively say that I never take it up without finding in it some new view, or light, or suggestion that I have not noticed before. That is the best characteristic of a thorough and profound book; and I believe this feature of the 'Origin of Species' explains why so many persons have ventured to pass judgment and criticisms upon it which are by no means worth the paper they are written on. Before concluding these lectures there is one point to which I must advert,--though, as Mr. Darwin has said nothing about man in his book, it concerns myself rather than him;--for I have strongly maintained on sundry occasions that if Mr. Darwin's views are sound, they apply as much to man as to the lower mammals, seeing that it is perfectly demonstrable that the structural differences which separate man from the apes are not greater than those which separate some apes from others. There cannot be the slightest doubt in the world that the argument which applies to the improvement of the horse from an earlier stock, or of ape from ape, applies to the improvement of man from some simpler and lower stock than man. There is not a single faculty--functional or structural, moral, intellectual, or instinctive,--there is no faculty whatever that is not capable of improvement; there is no faculty whatsoever which does not depend upon structure, and as structure tends to vary, it is capable of being improved. Well, I have taken a good deal of pains at various times to prove this, and I have endeavoured to meet the objections of those who maintain, that the structural differences between man and the lower animals are of so vast a character and enormous extent, that even if Mr. Darwin's views are correct, you cannot imagine this particular modification to take place. It is, in fact, easy matter to prove that, so far as structure is concerned, man differs to no greater extent from the animals which are immediately below him than these do from other members of the same order. Upon the other hand, there is no one who estimates more highly than I do the dignity of human nature, and the width of the gulf in intellectual and moral matters, which lies between man and the whole of the lower creation. But I find this very argument brought forward vehemently by some. "You say that man has proceeded from a modification of some lower animal, and you take pains to prove that the structural differences which are said to exist in his brain do not exist at all, and you teach that all functions, intellectual, moral, and others, are the expression or the result, in the long run, of structures, and of the molecular forces which they exert." It is quite true that I do so. "Well, but," I am told at once, somewhat triumphantly, "you say in the same breath that there is a great moral and intellectual chasm between man and the lower animals. How is this possible when you declare that moral and intellectual characteristics depend on structure, and yet tell us that there is no such gulf between the structure of man and that of the lower animals?" I think that objection is based upon a misconception of the real relations which exist between structure and function, between mechanism and work. Function is the expression of molecular forces and arrangements no doubt; but, does it follow from this, that variation in function so depends upon variation in structure that the former is always exactly proportioned to the latter? If there is no such relation, if the variation in function which follows on a variation in structure, may be enormously greater than the variation of the structure, then, you see, the objection falls to the ground. Take a couple of watches--made by the same maker, and as completely alike as possible; set them upon the table, and the function of each--which is its rate of going--will be performed in the same manner, and you shall be able to distinguish no difference between them; but let me take a pair of pincers, and if my hand is steady enough to do it, let me just lightly crush together the bearings of the balance-wheel, or force to a slightly different angle the teeth of the escapement of one of them, and of course you know the immediate result will be that the watch, so treated, from that moment will cease to go. But what proportion is there between the structural alteration and the functional result? Is it not perfectly obvious that the alteration is of the minutest kind, yet that slight as it is, it has produced an infinite difference in the performance of the functions of these two instruments? Well, now, apply that to the present question. What is it that constitutes and makes man what he is? What is it but his power of language--that language giving him the means of recording his experience--making every generation somewhat wiser than its predecessor,--more in accordance with the established order of the universe? What is it but this power of speech, of recording experience, which enables men to be men--looking before and after and, in some dim sense, understanding the working of this wondrous universe--and which distinguishes man from the whole of the brute world? I say that this functional difference is vast, unfathomable, and truly infinite in its consequences; and I say at the same time, that it may depend upon structural differences which shall be absolutely inappreciable to us with our present means of investigation. What is this very speech that we are talking about? I am speaking to you at this moment, but if you were to alter, in the minutest degree, the proportion of the nervous forces now active in the two nerves which supply the muscles of my glottis, I should become suddenly dumb. The voice is produced only so long as the vocal chords are parallel; and these are parallel only so long as certain muscles contract with exact equality; and that again depends on the equality of action of those two nerves I spoke of. So that a change of the minutest kind in the structure of one of these nerves, or in the structure of the part in which it originates, or of the supply of blood to that part, or of one of the muscles to which it is distributed, might render all of us dumb. But a race of dumb men, deprived of all communication with those who could speak, would be little indeed removed from the brutes. And the moral and intellectual difference between them and ourselves would be practically infinite, though the naturalist should not be able to find a single shadow of even specific structural difference. But let me dismiss this question now, and, in conclusion, let me say that you may go away with it as my mature conviction, that Mr. Darwin's work is the greatest contribution which has been made to biological science since the publication of the 'Regne Animal' of Cuvier, and since that of the 'History of Development' of Von Baer. I believe that if you strip it of its theoretical part it still remains one of the greatest encyclopaedias of biological doctrine that any one man ever brought forth; and I believe that, if you take it as the embodiment of an hypothesis, it is destined to be the guide of biological and psychological speculation for the next three or four generations. [Footnote 1: And as I conceive with very good reason; but if any objector urges that we cannot prove that they have been produced by artificial or natural selection, the objection must be admitted-- ultrasceptical as it is. But in science, scepticism is a duty.] 
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2930	----	CRITICISMS ON "THE ORIGIN OF SPECIES" 'The Natural History Review', 1864 [1] By Thomas H. Huxley In the course of the present year several foreign commentaries upon Mr. Darwin's great work have made their appearance. Those who have perused that remarkable chapter of the 'Antiquity of Man,' in which Sir Charles Lyell draws a parallel between the development of species and that of languages, will be glad to hear that one of the most eminent philologers of Germany, Professor Schleicher, has, independently, published a most instructive and philosophical pamphlet (an excellent notice of which is to be found in the 'Reader', for February 27th of this year) supporting similar views with all the weight of his special knowledge and established authority as a linguist. Professor Haeckel, to whom Schleicher addresses himself, previously took occasion, in his splendid monograph on the 'Radiolaria' [2], to express his high appreciation of, and general concordance with, Mr. Darwin's views. But the most elaborate criticisms of the 'Origin of Species' which have appeared are two works of very widely different merit, the one by Professor Kolliker, the well-known anatomist and histologist of Wurzburg; the other by M. Flourens, Perpetual Secretary of the French Academy of Sciences. Professor Kolliker's critical essay 'Upon the Darwinian Theory' is, like all that proceeds from the pen of that thoughtful and accomplished writer, worthy of the most careful consideration. It comprises a brief but clear sketch of Darwin's views, followed by an enumeration of the leading difficulties in the way of their acceptance; difficulties which would appear to be insurmountable to Professor Kolliker, inasmuch as he proposes to replace Mr. Darwin's Theory by one which he terms the 'Theory of Heterogeneous Generation.' We shall proceed to consider first the destructive, and secondly, the constructive portion of the essay. We regret to find ourselves compelled to dissent very widely from many of Professor Kolliker's remarks; and from none more thoroughly than from those in which he seeks to define what we may term the philosophical position of Darwinism. "Darwin," says Professor Kolliker, "is, in the fullest sense of the word, a Teleologist. He says quite distinctly (First Edition, pp. 199, 200) that every particular in the structure of an animal has been created for its benefit, and he regards the whole series of animal forms only from this point of view." And again: "7. The teleological general conception adopted by Darwin is a mistaken one. "Varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent. "The assumption that an organism exists only on account of some definite end in view, and represents something more than the incorporation of a general idea, or law, implies a one-sided conception of the universe. Assuredly, every organ has, and every organism fulfils, its end, but its purpose is not the condition of its existence. Every organism is also sufficiently perfect for the purpose it serves, and in that, at least, it is useless to seek for a cause of its improvement." It is singular how differently one and the same book will impress different minds. That which struck the present writer most forcibly on his first perusal of the 'Origin of Species' was the conviction that Teleology, as commonly understood, had received its deathblow at Mr. Darwin's hands. For the teleological argument runs thus: an organ or organism (A) is precisely fitted to perform a function or purpose (B); therefore it was specially constructed to perform that function. In Paley's famous illustration, the adaptation of all the parts of the watch to the function, or purpose, of showing the time, is held to be evidence that the watch was specially contrived to that end; on the ground, that the only cause we know of, competent to produce such an effect as a watch which shall keep time, is a contriving intelligence adapting the means directly to that end. Suppose, however, that any one had been able to show that the watch had not been made directly by any person, but that it was the result of the modification of another watch which kept time but poorly; and that this again had proceeded from a structure which could hardly be called a watch at all--seeing that it had no figures on the dial and the hands were rudimentary; and that going back and back in time we came at last to a revolving barrel as the earliest traceable rudiment of the whole fabric. And imagine that it had been possible to show that all these changes had resulted, first, from a tendency of the structure to vary indefinitely; and secondly, from something in the surrounding world which helped all variations in the direction of an accurate time-keeper, and checked all those in other directions; then it is obvious that the force of Paley's argument would be gone. For it would be demonstrated that an apparatus thoroughly well adapted to a particular purpose might be the result of a method of trial and error worked by unintelligent agents, as well as of the direct application of the means appropriate to that end, by an intelligent agent. Now it appears to us that what we have here, for illustration's sake, supposed to be done with the watch, is exactly what the establishment of Darwin's Theory will do for the organic world. For the notion that every organism has been created as it is and launched straight at a purpose, Mr. Darwin substitutes the conception of something which may fairly be termed a method of trial and error. Organisms vary incessantly; of these variations the few meet with surrounding conditions which suit them and thrive; the many are unsuited and become extinguished. According to Teleology, each organism is like a rifle bullet fired straight at a mark; according to Darwin, organisms are like grapeshot of which one hits something and the rest fall wide. For the teleologist an organism exists because it was made for the conditions in which it is found; for the Darwinian an organism exists because, out of many of its kind, it is the only one which has been able to persist in the conditions in which it is found. Teleology implies that the organs of every organism are perfect and cannot be improved; the Darwinian theory simply affirms that they work well enough to enable the organism to hold its own against such competitors as it has met with, but admits the possibility of indefinite improvement. But an example may bring into clearer light the profound opposition between the ordinary teleological, and the Darwinian, conception. Cats catch mice, small birds and the like, very well. Teleology tells us that they do so because they were expressly constructed for so doing--that they are perfect mousing apparatuses, so perfect and so delicately adjusted that no one of their organs could be altered, without the change involving the alteration of all the rest. Darwinism affirms on the contrary, that there was no express construction concerned in the matter; but that among the multitudinous variations of the Feline stock, many of which died out from want of power to resist opposing influences, some, the cats, were better fitted to catch mice than others, whence they throve and persisted, in proportion to the advantage over their fellows thus offered to them. Far from imagining that cats exist 'in order' to catch mice well, Darwinism supposes that cats exist 'because' they catch mice well--mousing being not the end, but the condition, of their existence. And if the cat type has long persisted as we know it, the interpretation of the fact upon Darwinian principles would be, not that the cats have remained invariable, but that such varieties as have incessantly occurred have been, on the whole, less fitted to get on in the world than the existing stock. If we apprehend the spirit of the 'Origin of Species' rightly, then, nothing can be more entirely and absolutely opposed to Teleology, as it is commonly understood, than the Darwinian Theory. So far from being a "Teleologist in the fullest sense of the word," we would deny that he is a Teleologist in the ordinary sense at all; and we should say that, apart from his merits as a naturalist, he has rendered a most remarkable service to philosophical thought by enabling the student of Nature to recognise, to their fullest extent, those adaptations to purpose which are so striking in the organic world, and which Teleology has done good service in keeping before our minds, without being false to the fundamental principles of a scientific conception of the universe. The apparently diverging teachings of the Teleologist and of the Morphologist are reconciled by the Darwinian hypothesis. But leaving our own impressions of the 'Origin of Species,' and turning to those passages especially cited by Professor Kolliker, we cannot admit that they bear the interpretation he puts upon them. Darwin, if we read him rightly, does 'not' affirm that every detail in the structure of an animal has been created for its benefit. His words are (p. 199):-- "The foregoing remarks lead me to say a few words on the protest lately made by some naturalists against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that very many structures have been created for beauty in the eyes of man, or for mere variety. This doctrine, if true, would be absolutely fatal to my theory--yet I fully admit that many structures are of no direct use to their possessor." And after sundry illustrations and qualifications, he concludes (p. 200):-- "Hence every detail of structure in every living creature (making some little allowance for the direct action of physical conditions) may be viewed either as having been of special use to some ancestral form, or as being now of special use to the descendants of this form--either directly, or indirectly, through the complex laws of growth." But it is one thing to say, Darwinically, that every detail observed in an animal's structure is of use to it, or has been of use to its ancestors; and quite another to affirm, teleologically, that every detail of an animal's structure has been created for its benefit. On the former hypothesis, for example, the teeth of the foetal Balaena have a meaning; on the latter, none. So far as we are aware, there is not a phrase in the 'Origin of Species', inconsistent with Professor Kolliker's position, that "varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent." On the contrary, Mr. Darwin writes (Summary of Chap. V.):-- "Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part varies more or less from the same part in the parents.... The external conditions of life, as climate and food, etc., seem to have induced some slight modifications. Habit, in producing constitutional differences, and use, in strengthening, and disuse, in weakening and diminishing organs, seem to have been more potent in their effects." And finally, as if to prevent all possible misconception, Mr. Darwin concludes his Chapter on Variation with these pregnant words:-- "Whatever the cause may be of each slight difference in the offspring from their parents--and a cause for each must exist--it is the steady accumulation, through natural selection of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure which the innumerable beings on the face of the earth are enabled to struggle with each other, and the best adapted to survive." We have dwelt at length upon this subject, because of its great general importance, and because we believe that Professor Kolliker's criticisms on this head are based upon a misapprehension of Mr. Darwin's views--substantially they appear to us to coincide with his own. The other objections which Professor Kolliker enumerates and discusses are the following [3]:-- "1. No transitional forms between existing species are known; and known varieties, whether selected or spontaneous, never go so far as to establish new species." To this Professor Kolliker appears to attach some weight. He makes the suggestion that the short-faced tumbler pigeon may be a pathological product. "2. No transitional forms of animals are met with among the organic remains of earlier epochs." Upon this, Professor Kolliker remarks that the absence of transitional forms in the fossil world, though not necessarily fatal to Darwin's views, weakens his case. "3. The struggle for existence does not take place." To this objection, urged by Pelzeln, Kolliker, very justly, attaches no weight. "4. A tendency of organisms to give rise to useful varieties, and a natural selection, do not exist. "The varieties which are found arise in consequence of manifold external influences, and it is not obvious why they all, or partially, should be particularly useful. Each animal suffices for its own ends, is perfect of its kind, and needs no further development. Should, however, a variety be useful and even maintain itself, there is no obvious reason why it should change any further. The whole conception of the imperfection of organisms and the necessity of their becoming perfected is plainly the weakest side of Darwin's Theory, and a 'pis aller' (Nothbehelf) because Darwin could think of no other principle by which to explain the metamorphoses which, as I also believe, have occurred." Here again we must venture to dissent completely from Professor Kolliker's conception of Mr. Darwin's hypothesis. It appears to us to be one of the many peculiar merits of that hypothesis that it involves no belief in a necessary and continual progress of organisms. Again, Mr. Darwin, if we read him aright, assumes no special tendency of organisms to give rise to useful varieties, and knows nothing of needs of development, or necessity of perfection. What he says is, in substance: All organisms vary. It is in the highest degree improbable that any given variety should have exactly the same relations to surrounding conditions as the parent stock. In that case it is either better fitted (when the variation may be called useful), or worse fitted, to cope with them. If better, it will tend to supplant the parent stock; if worse, it will tend to be extinguished by the parent stock. If (as is hardly conceivable) the new variety is so perfectly adapted to the conditions that no improvement upon it is possible,--it will persist, because, though it does not cease to vary, the varieties will be inferior to itself. If, as is more probable, the new variety is by no means perfectly adapted to its conditions, but only fairly well adapted to them, it will persist, so long as none of the varieties which it throws off are better adapted than itself. On the other hand, as soon as it varies in a useful way, i.e. when the variation is such as to adapt it more perfectly to its conditions, the fresh variety will tend to supplant the former. So far from a gradual progress towards perfection forming any necessary part of the Darwinian creed, it appears to us that it is perfectly consistent with indefinite persistence in one estate, or with a gradual retrogression. Suppose, for example, a return of the glacial epoch and a spread of polar climatal conditions over the whole globe. The operation of natural selection under these circumstances would tend, on the whole, to the weeding out of the higher organisms and the cherishing of the lower forms of life. Cryptogamic vegetation would have the advantage over Phanerogamic; Hydrozoa over Corals; Crustacea over Insecta, and Amphipoda and Isopoda over the higher Crustacea; Cetaceans and Seals over the Primates; the civilization of the Esquimaux over that of the European. "5. Pelzeln has also objected that if the later organisms have proceeded from the earlier, the whole developmental series, from the simplest to the highest, could not now exist; in such a case the simpler organisms must have disappeared." To this Professor Kolliker replies, with perfect justice, that the conclusion drawn by Pelzeln does not really follow from Darwin's premisses, and that, if we take the facts of Palaeontology as they stand, they rather support than oppose Darwin's theory. "6. Great weight must be attached to the objection brought forward by Huxley, otherwise a warm supporter of Darwin's hypothesis, that we know of no varieties which are sterile with one another, as is the rule among sharply distinguished animal forms. "If Darwin is right, it must be demonstrated that forms may be produced by selection, which, like the present sharply distinguished animal forms, are infertile, when coupled with one another, and this has not been done." The weight of this objection is obvious; but our ignorance of the conditions of fertility and sterility, the want of carefully conducted experiments extending over long series of years, and the strange anomalies presented by the results of the cross-fertilization of many plants, should all, as Mr. Darwin has urged, be taken into account in considering it. The seventh objection is that we have already discussed ('supra', p. 178). The eighth and last stands as follows:-- "8. The developmental theory of Darwin is not needed to enable us to understand the regular harmonious progress of the complete series of organic forms from the simpler to the more perfect. "The existence of general laws of Nature explains this harmony, even if we assume that all beings have arisen separately and independent of one another. Darwin forgets that inorganic nature, in which there can be no thought of genetic connexion of forms, exhibits the same regular plan, the same harmony, as the organic world; and that, to cite only one example, there is as much a natural system of minerals as of plants and animals." We do not feel quite sure that we seize Professor Kolliker's meaning here, but he appears to suggest that the observation of the general order and harmony which pervade inorganic nature, would lead us to anticipate a similar order and harmony in the organic world. And this is no doubt true, but it by no means follows that the particular order and harmony observed among them should be that which we see. Surely the stripes of dun horses, and the teeth of the foetal 'Balaena', are not explained by the "existence of general laws of Nature." Mr. Darwin endeavours to explain the exact order of organic nature which exists; not the mere fact that there is some order. And with regard to the existence of a natural system of minerals; the obvious reply is that there may be a natural classification of any objects--of stones on a sea-beach, or of works of art; a natural classification being simply an assemblage of objects in groups, so as to express their most important and fundamental resemblances and differences. No doubt Mr. Darwin believes that those resemblances and differences upon which our natural systems or classifications of animals and plants are based, are resemblances and differences which have been produced genetically, but we can discover no reason for supposing that he denies the existence of natural classifications of other kinds. And, after all, is it quite so certain that a genetic relation may not underlie the classification of minerals? The inorganic world has not always been what we see it. It has certainly had its metamorphoses, and, very probably, a long "Entwickelungsgeschichte" out of a nebular blastema. Who knows how far that amount of likeness among sets of minerals, in virtue of which they are now grouped into families and orders, may not be the expression of the common conditions to which that particular patch of nebulous fog, which may have been constituted by their atoms, and of which they may be, in the strictest sense, the descendants, was subjected? It will be obvious from what has preceded, that we do not agree with Professor Kolliker in thinking the objections which he brings forward so weighty as to be fatal to Darwin's view. But even if the case were otherwise, we should be unable to accept the "Theory of Heterogeneous Generation" which is offered as a substitute. That theory is thus stated:-- "The fundamental conception of this hypothesis is, that, under the influence of a general law of development, the germs of organisms produce others different from themselves. This might happen (1) by the fecundated ova passing, in the course of their development, under particular circumstances, into higher forms; (2) by the primitive and later organisms producing other organisms without fecundation, out of germs or eggs (Parthenogenesis)." In favour of this hypothesis, Professor Kolliker adduces the well-known facts of Agamogenesis, or "alternate generation"; the extreme dissimilarity of the males and females of many animals; and of the males, females, and neuters of those insects which live in colonies: and he defines its relations to the Darwinian theory as follows:-- "It is obvious that my hypothesis is apparently very similar to Darwin's, inasmuch as I also consider that the various forms of animals have proceeded directly from one another. My hypothesis of the creation of organisms by heterogeneous generation, however, is distinguished very essentially from Darwin's by the entire absence of the principle of useful variations and their natural selection: and my fundamental conception is this, that a great plan of development lies at the foundation of the origin of the whole organic world, impelling the simpler forms to more and more complex developments. How this law operates, what influences determine the development of the eggs and germs, and impel them to assume constantly new forms, I naturally cannot pretend to say; but I can at least adduce the great analogy of the alternation of generations. If a 'Bipinnaria', a 'Brachialaria', a 'Pluteus', is competent to produce the Echinoderm, which is so widely different from it; if a hydroid polype can produce the higher Medusa; if the vermiform Trematode 'nurse' can develop within itself the very unlike 'Cercaria', it will not appear impossible that the egg, or ciliated embryo, of a sponge, for once, under special conditions, might become a hydroid polype, or the embryo of a Medusa, an Echinoderm." It is obvious, from these extracts, that Professor Kolliker's hypothesis is based upon the supposed existence of a close analogy between the phenomena of Agamogenesis and the production of new species from pre-existing ones. But is the analogy a real one? We think that it is not, and, by the hypothesis, cannot be. For what are the phenomena of Agamogenesis, stated generally? An impregnated egg develops into an asexual form, A; this gives rise, asexually, to a second form or forms, B, more or less different from A. B may multiply asexually again; in the simpler cases, however, it does not, but, acquiring sexual characters, produces impregnated eggs from whence A, once more, arises. No case of Agamogenesis is known in which, 'when A differs widely from B', it is itself capable of sexual propagation. No case whatever is known in which the progeny of B, by sexual generation, is other than a reproduction of A. But if this be a true statement of the nature of the process of Agamogenesis, how can it enable us to comprehend the production of new species from already existing ones? Let us suppose Hyaenas to have preceded Dogs, and to have produced the latter in this way. Then the Hyena will represent A, and the Dog, B. The first difficulty that presents itself is that the Hyena must be asexual, or the process will be wholly without analogy in the world of Agamogenesis. But passing over this difficulty, and supposing a male and female Dog to be produced at the same time from the Hyaena stock, the progeny of the pair, if the analogy of the simpler kinds of Agamogenesis [4] is to be followed, should be a litter, not of puppies, but of young Hyenas. For the Agamogenetic series is always, as we have seen, A: B: A: B, etc.; whereas, for the production of a new species, the series must be A: B: B: B, etc. The production of new species, or genera, is the extreme permanent divergence from the primitive stock. All known Agamogenetic processes, on the other hand, end in a complete return to the primitive stock. How then is the production of new species to be rendered intelligible by the analogy of Agamogenesis? The other alternative put by Professor Kolliker--the passage of fecundated ova in the course of their development into higher forms--would, if it occurred, be merely an extreme case of variation in the Darwinian sense, greater in degree than, but perfectly similar in kind to, that which occurred when the well-known Ancon Ram was developed from an ordinary Ewe's ovum. Indeed we have always thought that Mr. Darwin has unnecessarily hampered himself by adhering so strictly to his favourite "Natura non facit saltum." We greatly suspect that she does make considerable jumps in the way of variation now and then, and that these saltations give rise to some of the gaps which appear to exist in the series of known forms. Strongly and freely as we have ventured to disagree with Professor Kolliker, we have always done so with regret, and we trust without violating that respect which is due, not only to his scientific eminence and to the careful study which he has devoted to the subject, but to the perfect fairness of his argumentation, and the generous appreciation of the worth of Mr. Darwin's labours which he always displays. It would be satisfactory to be able to say as much for M. Flourens. But the Perpetual Secretary of the French Academy of Sciences deals with Mr. Darwin as the first Napoleon would have treated an "ideologue;" and while displaying a painful weakness of logic and shallowness of information, assumes a tone of authority, which always touches upon the ludicrous, and sometimes passes the limits of good breeding. For example (p. 56):-- "M. Darwin continue: 'Aucune distinction absolue n'a ete et ne pout etre etablie entre les especes et les varietes.' Je vous ai deja dit que vous vous trompiez; une distinction absolue separe les varietes d'avec les especes." "Je vous ai deja dit; moi, M. le Secretaire perpetuel de l'Academie des Sciences: et vous 'Qui n'etes rien, Pas meme Academicien;' what do you mean by asserting the contrary?' Being devoid of the blessings of an Academy in England, we are unaccustomed to see our ablest men treated in this fashion, even by a "Perpetual Secretary." Or again, considering that if there is any one quality of Mr. Darwin's work to which friends and foes have alike borne witness, it is his candour and fairness in admitting and discussing objections, what is to be thought of M. Flourens' assertion, that "M. Darwin ne cite que les auteurs qui partagent ses opinions." (P. 40.) Once more (p. 65):-- "Enfin l'ouvrage de M. Darwin a paru. On ne peut qu'etre frappe du talent de l'auteur. Mais que d'idees obscures, que d'idees fausses! Quel jargon metaphysique jete mal a propos dans l'histoire naturelle, qui tombe dans le galimatias des qu'elle sort des idees claires, des idees justes! Quel langage pretentieux et vide! Quelles personifications pueriles et surannees! O lucidite! O solidite de l'esprit Francais, que devenez-vous?" "Obscure ideas," "metaphysical jargon," "pretentious and empty language," "puerile and superannuated personifications." Mr. Darwin has many and hot opponents on this side of the Channel and in Germany, but we do not recollect to have found precisely these sins in the long catalogue of those hitherto laid to his charge. It is worth while, therefore, to examine into these discoveries effected solely by the aid of the "lucidity and solidity" of the mind of M. Flourens. According to M. Flourens, Mr. Darwin's great error is that he has personified Nature (p. 10), and further that he has "imagined a natural selection: he imagines afterwards that this power of selection (pouvoir d'lire) which he gives to Nature is similar to the power of man. These two suppositions admitted, nothing stops him: he plays with Nature as he likes, and makes her do all he pleases." (P. 6.) And this is the way M. Flourens extinguishes natural selection: "Voyons donc encore une fois, ce qu'il peut y avoir de fonde dans ce qu'on nomme election naturelle. "L'election naturelle n'est sous un autre nom que la nature. Pour un etre organise, la nature n'est que l'organisation, ni plus ni moins. "Il faudra donc aussi personnifier l'organisation, et dire que l'organisation choisit l'organisation. L'election naturelle est cette forme substantielle dont on jouait autrefois avec tant de facilite. Aristote disait que 'Si l'art de batir etait dans le bois, cet art agirait comme la nature.' A la place de l'art de batir M. Darwin met l'election naturelle, et c'est tout un: l'un n'est pas plus chimerique que l'autre." (P.31.) And this is really all that M. Flourens can make of Natural Selection. We have given the original, in fear lest a translation should be regarded as a travesty; but with the original before the reader, we may try to analyse the passage. "For an organized being, Nature is only organization, neither more nor less." Organized beings then have absolutely no relation to inorganic nature: a plant does not, depend on soil or sunshine, climate, depth in the ocean, height above it; the quantity of saline matters in water have no influence upon animal life; the substitution of carbonic acid for oxygen in our atmosphere would hurt nobody! That these are absurdities no one should know better than M. Flourens; but they are logical deductions from the assertion just quoted, and from the further statement that natural selection means only that "organization chooses and selects organization." For if it be once admitted (what no sane man denies) that the chances of life of any given organism are increased by certain conditions (A) and diminished by their opposites (B), then it is mathematically certain that any change of conditions in the direction of (A) will exercise a selective influence in favour of that organism, tending to its increase and multiplication, while any change in the direction of (B) will exercise a selective influence against that organism, tending to its decrease and extinction. Or, on the other hand, conditions remaining the same, let a given organism vary (and no one doubts that they do vary) in two directions: into one form (a) better fitted to cope with these conditions than the original stock, and a second (b) less well adapted to them. Then it is no less certain that the conditions in question must exercise a selective influence in favour of (a) and against ( b), so that (a) will tend to predominance, and (b) to extirpation. That M. Flourens should be unable to perceive the logical necessity of these simple arguments, which lie at the foundation of all Mr. Darwin's reasoning; that he should confound an irrefragable deduction from the observed relations of organisms to the conditions which lie around them, with a metaphysical "forme substantielle," or a chimerical personification of the powers of Nature, would be incredible, were it not that other passages of his work leave no room for doubt upon the subject. "On imagine une 'election naturelle' que, pour plus de menagement, on me dit etre inconsciente, sans s'apercevoir que le contre-sens litteral est precisement la: 'election inconsciente'." (P. 52.) "J'ai deja dit ce qu'il faut penser de 'l'election naturelle'. Ou 'l'election naturelle' n'est rien, ou c'est la nature: mais la nature douee 'd'election', mais la nature personnifiee: derniere erreur du dernier siecle: Le xixe fait plus de personnifications." (P. 53.) M. Flourens cannot imagine an unconscious selection--it is for him a contradiction in terms. Did M. Flourens ever visit one of the prettiest watering-places of "la belle France," the Baie d'Arcachon? If so, he will probably have passed through the district of the Landes, and will have had an opportunity of observing the formation of "dunes" on a grand scale. What are these "dunes"? The winds and waves of the Bay of Biscay have not much consciousness, and yet they have with great care "selected," from among an infinity of masses of silex of all shapes and sizes, which have been submitted to their action, all the grains of sand below a certain size, and have heaped them by themselves over a great area. This sand has been "unconsciously selected" from amidst the gravel in which it first lay with as much precision as if man had "consciously selected" it by the aid of a sieve. Physical Geology is full of such selections--of the picking out of the soft from the hard, of the soluble from the insoluble, of the fusible from the infusible, by natural agencies to which we are certainly not in the habit of ascribing consciousness. But that which wind and sea are to a sandy beach, the sum of influences, which we term the "conditions of existence," is to living organisms. The weak are sifted out from the strong. A frosty night "selects" the hardy plants in a plantation from among the tender ones as effectually as if it were the wind, and they, the sand and pebbles, of our illustration; or, on the other hand, as if the intelligence of a gardener had been operative in cutting the weaker organisms down. The thistle, which has spread over the Pampas, to the destruction of native plants, has been more effectually "selected" by the unconscious operation of natural conditions than if a thousand agriculturists had spent their time in sowing it. It is one of Mr. Darwin's many great services to Biological science that he has demonstrated the significance of these facts. He has shown that--given variation and given change of conditions--the inevitable result is the exercise of such an influence upon organisms that one is helped and another is impeded; one tends to predominate, another to disappear; and thus the living world bears within itself, and is surrounded by, impulses towards incessant change. But the truths just stated are as certain as any other physical laws, quite independently of the truth, or falsehood, of the hypothesis which Mr. Darwin has based upon them; and that M. Flourens, missing the substance and grasping at a shadow, should be blind to the admirable exposition of them, which Mr. Darwin has given, and see nothing there but a "derniere erreur du dernier siecle "--a personification of Nature--leads us indeed to cry with him: "O lucidite! O solidite de l'esprit Francais, que devenez-vous?" M. Flourens has, in fact, utterly failed to comprehend the first principles of the doctrine which he assails so rudely. His objections to details are of the old sort, so battered and hackneyed on this side of the Channel, that not even a Quarterly Reviewer could be induced to pick them up for the purpose of pelting Mr. Darwin over again. We have Cuvier and the mummies; M. Roulin and the domesticated animals of America; the difficulties presented by hybridism and by Palaeontology; Darwinism a 'rifacciamento' of De Maillet and Lamarck; Darwinism a system without a commencement, and its author bound to believe in M. Pouchet, etc. etc. How one knows it all by heart, and with what relief one reads at p. 65-- "Je laisse M. Darwin!" But we cannot leave M. Flourens without calling our readers' attention to his wonderful tenth chapter, "De la Preexistence des Germes et de l'Epigenese," which opens thus:-- "Spontaneous generation is only a chimaera. This point established, two hypotheses remain: that of 'pre-existence' and that of 'epigenesis'. The one of these hypotheses has as little foundation as the other." (P. 163.) "The doctrine of 'epigenesis' is derived from Harvey: following by ocular inspection the development of the new being in the Windsor does, he saw each part appear successively, and taking the moment of 'appearance' for the moment of 'formation' he imagined 'epigenesis'." (P. 165.) On the contrary, says M. Flourens (p. 167), "The new being is formed at a stroke ('tout d'un coup') as a whole, instantaneously; it is not formed part by part, and at different times. It is formed at once at the single 'individual' moment at which the conjunction of the male and female elements takes place." It will be observed that M. Flourens uses language which cannot be mistaken. For him, the labours of von Baer, of Rathke, of Coste, and their contemporaries and successors in Germany, France, and England, are non-existent: and, as Darwin "imagina" natural selection, so Harvey "imagina" that doctrine which gives him an even greater claim to the veneration of posterity than his better known discovery of the circulation of the blood. Language such as that we have quoted is, in fact, so preposterous, so utterly incompatible with anything but absolute ignorance of some of the best established facts, that we should have passed it over in silence had it not appeared to afford some clue to M. Flourens' unhesitating, 'a priori', repudiation of all forms of the doctrine of progressive modification of living beings. He whose mind remains uninfluenced by an acquaintance with the phenomena of development, must indeed lack one of the chief motives towards the endeavour to trace a genetic relation between the different existing forms of life. Those who are ignorant of Geology, find no difficulty in believing that the world was made as it is; and the shepherd, untutored in history, sees no reason to regard the green mounds which indicate the site of a Roman camp, as aught but part and parcel of the primeval hill-side. So M. Flourens, who believes that embryos are formed "tout d'un coup," naturally finds no difficulty in conceiving that species came into existence in the same way. [Footnote 1: The Natural History Review', 1864. 1. UEBER DIE DARWIN'SCHE SCH PFUNGSTHEORIE; EIN VORTRAG, VON A. K LLIKER. Leipzig, 1864. 2. EXAMINATION DU LIVRE DE M. DARWIN SUR L'ORIGINE DES ESPECES. PAR P. FLOURENS. Paris, 1864.] [Footnote 2: 'Die Radiolarien: eine Monographie', p. 231.] [Footnote 3: Space will not allow us to give Professor Kolliker's arguments in detail; our readers will find a full and accurate version of them in the 'Reader' for August 13th and 20th, 1864.] [Footnote 4: If, on the contrary, we follow the analogy of the more complex forms of Agamogenesis, such as that exhibited by some 'Trematoda' and by the 'Aphides', the Hyaena must produce, asexually, a brood of asexual Dogs, from which other sexless Dogs must proceed. At the end of a certain number of terms of the series, the Dogs would acquire sexes and generate young; but these young would be, not Dogs, but Hyaenas. In fact, we have 'demonstrated', in Agamogenetic phenomena, that inevitable recurrence to the original type, which is 'asserted' to be true of variations in general, by Mr. Darwin's opponents; and which, if the assertion could be changed into a demonstration would, in fact, be fatal to his hypothesis.] 
2929	----	THE ORIGIN OF SPECIES [1] By Thomas H. Huxley MR. DARWIN'S long-standing and well-earned scientific eminence probably renders him indifferent to that social notoriety which passes by the name of success; but if the calm spirit of the philosopher have not yet wholly superseded the ambition and the vanity of the carnal man within him, he must be well satisfied with the results of his venture in publishing the 'Origin of Species'. Overflowing the narrow bounds of purely scientific circles, the "species question" divides with Italy and the Volunteers the attention of general society. Everybody has read Mr. Darwin's book, or, at least, has given an opinion upon its merits or demerits; pietists, whether lay or ecclesiastic, decry it with the mild railing which sounds so charitable; bigots denounce it with ignorant invective; old ladies of both sexes consider it a decidedly dangerous book, and even savants, who have no better mud to throw, quote antiquated writers to show that its author is no better than an ape himself; while every philosophical thinker hails it as a veritable Whitworth gun in the armoury of liberalism; and all competent naturalists and physiologists, whatever their opinions as to the ultimate fate of the doctrines put forth, acknowledge that the work in which they are embodied is a solid contribution to knowledge and inaugurates a new epoch in natural history. Nor has the discussion of the subject been restrained within the limits of conversation. When the public is eager and interested, reviewers must minister to its wants; and the genuine 'litterateur' is too much in the habit of acquiring his knowledge from the book he judges--as the Abyssinian is said to provide himself with steaks from the ox which carries him--to be withheld from criticism of a profound scientific work by the mere want of the requisite preliminary scientific acquirement; while, on the other hand, the men of science who wish well to the new views, no less than those who dispute their validity, have naturally sought opportunities of expressing their opinions. Hence it is not surprising that almost all the critical journals have noticed Mr. Darwin's work at greater or less length; and so many disquisitions, of every degree of excellence, from the poor product of ignorance, too often stimulated by prejudice, to the fair and thoughtful essay of the candid student of Nature, have appeared, that it seems an almost hopeless task to attempt to say anything new upon the question. But it may be doubted if the knowledge and acumen of prejudged scientific opponents, or the subtlety of orthodox special pleaders, have yet exerted their full force in mystifying the real issues of the great controversy which has been set afoot, and whose end is hardly likely to be seen by this generation; so that, at this eleventh hour, and even failing anything new, it may be useful to state afresh that which is true, and to put the fundamental positions advocated by Mr. Darwin in such a form that they may be grasped by those whose special studies lie in other directions. And the adoption of this course may be the more advisable, because, notwithstanding its great deserts, and indeed partly on account of them, the 'Origin of Species' is by no means an easy book to read--if by reading is implied the full comprehension of an author's meaning. We do not speak jestingly in saying that it is Mr. Darwin's misfortune to know more about the question he has taken up than any man living. Personally and practically exercised in zoology, in minute anatomy, in geology; a student of geographical distribution, not on maps and in museums only, but by long voyages and laborious collection; having largely advanced each of these branches of science, and having spent many years in gathering and sifting materials for his present work, the store of accurately registered facts upon which the author of the 'Origin of Species' is able to draw at will is prodigious. But this very superabundance of matter must have been embarrassing to a writer who, for the present, can only put forward an abstract of his views; and thence it arises, perhaps, that notwithstanding the clearness of the style, those who attempt fairly to digest the book find much of it a sort of intellectual pemmican--a mass of facts crushed and pounded into shape, rather than held together by the ordinary medium of an obvious logical bond; due attention will, without doubt, discover this bond, but it is often hard to find. Again, from sheer want of room, much has to be taken for granted which might readily enough be proved; and hence, while the adept, who can supply the missing links in the evidence from his own knowledge, discovers fresh proof of the singular thoroughness with which all difficulties have been considered and all unjustifiable suppositions avoided, at every reperusal of Mr. Darwin's pregnant paragraphs, the novice in biology is apt to complain of the frequency of what he fancies is gratuitous assumption. Thus while it may be doubted if, for some years, any one is likely to be competent to pronounce judgment on all the issues raised by Mr. Darwin, there is assuredly abundant room for him, who, assuming the humbler, though perhaps as useful, office of an interpreter between the 'Origin of Species' and the public, contents himself with endeavouring to point out the nature of the problems which it discusses; to distinguish between the ascertained facts and the theoretical views which it contains; and finally, to show the extent to which the explanation it offers satisfies the requirements of scientific logic. At any rate, it is this office which we purpose to undertake in the following pages. It may be safely assumed that our readers have a general conception of the nature of the objects to which the word "species" is applied; but it has, perhaps, occurred to a few, even to those who are naturalists 'ex professo', to reflect, that, as commonly employed, the term has a double sense and denotes two very different orders of relations. When we call a group of animals, or of plants, a species, we may imply thereby, either that all these animals or plants have some common peculiarity of form or structure; or, we may mean that they possess some common functional character. That part of biological science which deals with form and structure is called Morphology--that which concerns itself with function, Physiology--so that we may conveniently speak of these two senses, or aspects, of "species"--the one as morphological, the other as physiological. Regarded from the former point of view, a species is nothing more than a kind of animal or plant, which is distinctly definable from all others, by certain constant, and not merely sexual, morphological peculiarities. Thus horses form a species, because the group of animals to which that name is applied is distinguished from all others in the world by the following constantly associated characters. They have--1, A vertebral column; 2, Mammae; 3, A placental embryo; 4, Four legs; 5, A single well-developed toe in each foot provided with a hoof; 6, A bushy tail; and 7, Callosities on the inner sides of both the fore and the hind legs. The asses, again, form a distinct species, because, with the same characters, as far as the fifth in the above list, all asses have tufted tails, and have callosities only on the inner side of the fore-legs. If animals were discovered having the general characters of the horse, but sometimes with callosities only on the fore-legs, and more or less tufted tails; or animals having the general characters of the ass, but with more or less bushy tails, and sometimes with callosities on both pairs of legs, besides being intermediate in other respects--the two species would have to be merged into one. They could no longer be regarded as morphologically distinct species, for they would not be distinctly definable one from the other. However bare and simple this definition of species may appear to be, we confidently appeal to all practical naturalists, whether zoologists, botanists, or palaeontologists, to say if, in the vast majority of cases, they know, or mean to affirm anything more of the group of animals or plants they so denominate than what has just been stated. Even the most decided advocates of the received doctrines respecting species admit this. "I apprehend," says Professor Owen [2], "that few naturalists nowadays, in describing and proposing a name for what they call 'a new species,' use that term to signify what was meant by it twenty or thirty years ago; that is, an originally distinct creation, maintaining its primitive distinction by obstructive generative peculiarities. The proposer of the new species now intends to state no more than he actually knows; as, for example, that the differences on which he founds the specific character are constant in individuals of both sexes, so far as observation has reached; and that they are not due to domestication or to artificially superinduced external circumstances, or to any outward influence within his cognizance; that the species is wild, or is such as it appears by Nature." If we consider, in fact, that by far the largest proportion of recorded existing species are known only by the study of their skins, or bones, or other lifeless exuvia; that we are acquainted with none, or next to none, of their physiological peculiarities, beyond those which can be deduced from their structure, or are open to cursory observation; and that we cannot hope to learn more of any of those extinct forms of life which now constitute no inconsiderable proportion of the known Flora and Fauna of the world: it is obvious that the definitions of these species can be only of a purely structural, or morphological, character. It is probable that naturalists would have avoided much confusion of ideas if they had more frequently borne the necessary limitations of our knowledge in mind. But while it may safely be admitted that we are acquainted with only the morphological characters of the vast majority of species--the functional or physiological, peculiarities of a few have been carefully investigated, and the result of that study forms a large and most interesting portion of the physiology of reproduction. The student of Nature wonders the more and is astonished the less, the more conversant he becomes with her operations; but of all the perennial miracles she offers to his inspection, perhaps the most worthy of admiration is the development of a plant or of an animal from its embryo. Examine the recently laid egg of some common animal, such as a salamander or newt. It is a minute spheroid in which the best microscope will reveal nothing but a structureless sac, enclosing a glairy fluid, holding granules in suspension. But strange possibilities lie dormant in that semi-fluid globule. Let a moderate supply of warmth reach its watery cradle, and the plastic matter undergoes changes so rapid, yet so steady and purposelike in their succession, that one can only compare them to those operated by a skilled modeller upon a formless lump of clay. As with an invisible trowel, the mass is divided and subdivided into smaller and smaller portions, until it is reduced to an aggregation of granules not too large to build withal the finest fabrics of the nascent organism. And, then, it is as if a delicate finger traced out the line to be occupied by the spinal column, and moulded the contour of the body; pinching up the head at one end, the tail at the other, and fashioning flank and limb into due salamandrine proportions, in so artistic a way, that, after watching the process hour by hour, one is almost involuntarily possessed by the notion, that some more subtle aid to vision than an achromatic, would show the hidden artist, with his plan before him, striving with skilful manipulation to perfect his work. As life advances, and the young amphibian ranges the waters, the terror of his insect contemporaries, not only are the nutritious particles supplied by its prey, by the addition of which to its frame, growth takes place, laid down, each in its proper spot, and in such due proportion to the rest, as to reproduce the form, the colour, and the size, characteristic of the parental stock; but even the wonderful powers of reproducing lost parts possessed by these animals are controlled by the same governing tendency. Cut off the legs, the tail, the jaws, separately or all together, and, as Spallanzani showed long ago, these parts not only grow again, but the redintegrated limb is formed on the same type as those which were lost. The new jaw, or leg, is a newt's, and never by any accident more like that of a frog. What is true of the newt is true of every animal and of every plant; the acorn tends to build itself up again into a woodland giant such as that from whose twig it fell; the spore of the humblest lichen reproduces the green or brown incrustation which gave it birth; and at the other end of the scale of life, the child that resembled neither the paternal nor the maternal side of the house would be regarded as a kind of monster. So that the one end to which, in all living beings, the formative impulse is tending--the one scheme which the Archaeus of the old speculators strives to carry out, seems to be to mould the offspring into the likeness of the parent. It is the first great law of reproduction, that the offspring tends to resemble its parent or parents, more closely than anything else. Science will some day show us how this law is a necessary consequence of the more general laws which govern matter; but, for the present, more can hardly be said than that it appears to be in harmony with them. We know that the phenomena of vitality are not something apart from other physical phenomena, but one with them; and matter and force are the two names of the one artist who fashions the living as well as the lifeless. Hence living bodies should obey the same great laws as other matter--nor, throughout Nature, is there a law of wider application than this, that a body impelled by two forces takes the direction of their resultant. But living bodies may be regarded as nothing but extremely complex bundles of forces held in a mass of matter, as the complex forces of a magnet are held in the steel by its coercive force; and, since the differences of sex are comparatively slight, or, in other words, the sum of the forces in each has a very similar tendency, their resultant, the offspring, may reasonably be expected to deviate but little from a course parallel to either, or to both. Represent the reason of the law to ourselves by what physical metaphor or analogy we will, however, the great matter is to apprehend its existence and the importance of the consequences deducible from it. For things which are like to the same are like to one another; and if; in a great series of generations, every offspring is like its parent, it follows that all the offspring and all the parents must be like one another; and that, given an original parental stock, with the opportunity of undisturbed multiplication, the law in question necessitates the production, in course of time, of an indefinitely large group, the whole of whose members are at once very similar and are blood relations, having descended from the same parent, or pair of parents. The proof that all the members of any given group of animals, or plants, had thus descended, would be ordinarily considered sufficient to entitle them to the rank of physiological species, for most physiologists consider species to be definable as "the offspring of a single primitive stock." But though it is quite true that all those groups we call species 'may', according to the known laws of reproduction, have descended from a single stock, and though it is very likely they really have done so, yet this conclusion rests on deduction and can hardly hope to establish itself upon a basis of observation. And the primitiveness of the supposed single stock, which, after all, is the essential part of the matter, is not only a hypothesis, but one which has not a shadow of foundation, if by "primitive" he meant "independent of any other living being." A scientific definition, of which an unwarrantable hypothesis forms an essential part, carries its condemnation within itself; but, even supposing such a definition were, in form, tenable, the physiologist who should attempt to apply it in Nature would soon find himself involved in great, if not inextricable, difficulties. As we have said, it is indubitable that offspring 'tend' to resemble the parental organism, but it is equally true that the similarity attained never amounts to identity, either in form or in structure. There is always a certain amount of deviation, not only from the precise characters of a single parent, but when, as in most animals and many plants, the sexes are lodged in distinct individuals, from an exact mean between the two parents. And indeed, on general principles, this slight deviation seems as intelligible as the general similarity, if we reflect how complex the co-operating "bundles of forces" are, and how improbable it is that, in any case, their true resultant shall coincide with any mean between the more obvious characters of the two parents. Whatever be its cause, however, the co-existence of this tendency to minor variation with the tendency to general similarity, is of vast importance in its bearing on the question of the origin of species. As a general rule, the extent to which an offspring differs from its parent is slight enough; but, occasionally, the amount of difference is much more strongly marked, and then the divergent offspring receives the name of a Variety. Multitudes, of what there is every reason to believe are such varieties, are known, but the origin of very few has been accurately recorded, and of these we will select two as more especially illustrative of the main features of variation. The first of them is that of the "Ancon," or "Otter" sheep, of which a careful account is given by Colonel David Humphreys, F.R.S., in a letter to Sir Joseph Banks, published in the Philosophical Transactions for 1813. It appears that one Seth Wright, the proprietor of a farm on the banks of the Charles River, in Massachusetts, possessed a flock of fifteen ewes and a ram of the ordinary kind. In the year 1791, one of the ewes presented her owner with a male lamb, differing, for no assignable reason, from its parents by a proportionally long body and short bandy legs, whence it was unable to emulate its relatives in those sportive leaps over the neighbours' fences, in which they were in the habit of indulging, much to the good farmer's vexation. The second case is that detailed by a no less unexceptionable authority than Reaumur, in his 'Art de faire eclore les Poulets'. A Maltese couple, named Kelleia, whose hands and feet were constructed upon the ordinary human model, had born to them a son, Gratio, who possessed six perfectly movable fingers on each hand, and six toes, not quite so well formed, on each foot. No cause could be assigned for the appearance of this unusual variety of the human species. Two circumstances are well worthy of remark in both these cases. In each, the variety appears to have arisen in full force, and, as it were, 'per saltum'; a wide and definite difference appearing, at once, between the Ancon ram and the ordinary sheep; between the six-fingered and six-toed Gratio Kelleia and ordinary men. In neither case is it possible to point out any obvious reason for the appearance of the variety. Doubtless there were determining causes for these as for all other phenomena; but they do not appear, and we can be tolerably certain that what are ordinarily understood as changes in physical conditions, as in climate, in food, or the like, did not take place and had nothing to do with the matter. It was no case of what is commonly called adaptation to circumstances; but, to use a conveniently erroneous phrase, the variations arose spontaneously. The fruitless search after final causes leads their pursuers a long way; but even those hardy teleologists, who are ready to break through all the laws of physics in chase of their favourite will-o'-the-wisp, may be puzzled to discover what purpose could be attained by the stunted legs of Seth Wright's ram or the hexadactyle members of Gratio Kelleia. Varieties then arise we know not why; and it is more than probable that the majority of varieties have arisen in this "spontaneous" manner, though we are, of course, far from denying that they may be traced, in some cases, to distinct external influences; which are assuredly competent to alter the character of the tegumentary covering, to change colour, to increase or diminish the size of muscles, to modify constitution, and, among plants, to give rise to the metamorphosis of stamens into petals, and so forth. But however they may have arisen, what especially interests us at present is, to remark that, once in existence, varieties obey the fundamental law of reproduction that like tends to produce like; and their offspring exemplify it by tending to exhibit the same deviation from the parental stock as themselves. Indeed, there seems to be, in many instances, a pre-potent influence about a newly-arisen variety which gives it what one may call an unfair advantage over the normal descendants from the same stock. This is strikingly exemplified by the case of Gratio Kelleia, who married a woman with the ordinary pentadactyle extremities, and had by her four children, Salvator, George, Andre, and Marie. Of these children Salvator, the eldest boy, had six fingers and six toes, like his father; the second and third, also boys, had five fingers and five toes, like their mother, though the hands and feet of George were slightly deformed. The last, a girl, had five fingers and five toes, but the thumbs were slightly deformed. The variety thus reproduced itself purely in the eldest, while the normal type reproduced itself purely in the third, and almost purely in the second and last: so that it would seem, at first, as if the normal type were more powerful than the variety. But all these children grew up and intermarried with normal wives and husband, and then, note what took place: Salvator had four children, three of whom exhibited the hexadactyle members of their grandfather and father, while the youngest had the pentadactyle limbs of the mother and grandmother; so that here, notwithstanding a double pentadactyle dilution of the blood, the hexadactyle variety had the best of it. The same pre-potency of the variety was still more markedly exemplified in the progeny of two of the other children, Marie and George. Marie (whose thumbs only were deformed) gave birth to a boy with six toes, and three other normally formed children; but George, who was not quite so pure a pentadactyle, begot, first, two girls, each of whom had six fingers and toes; then a girl with six fingers on each hand and six toes on the right foot, but only five toes on the left; and lastly, a boy with only five fingers and toes. In these instances, therefore, the variety, as it were, leaped over one generation to reproduce itself in full force in the next. Finally, the purely pentadactyle Andre was the father of many children, not one of whom departed from the normal parental type. If a variation which approaches the nature of a monstrosity can strive thus forcibly to reproduce itself, it is not wonderful that less aberrant modifications should tend to be preserved even more strongly; and the history of the Ancon sheep is, in this respect, particularly instructive. With the "'cuteness" characteristic of their nation, the neighbours of the Massachusetts farmer imagined it would be an excellent thing if all his sheep were imbued with the stay-at-home tendencies enforced by Nature upon the newly-arrived ram; and they advised Wright to kill the old patriarch of his fold, and install the Ancon ram in his place. The result justified their sagacious anticipations, and coincided very nearly with what occurred to the progeny of Gratio Kelleia. The young lambs were almost always either pure Ancons, or pure ordinary sheep. [3] But when sufficient Ancon sheep were obtained to interbreed with one another, it was found that the offspring was always pure Ancon. Colonel Humphreys, in fact, states that he was acquainted with only "one questionable case of a contrary nature." Here, then, is a remarkable and well-established instance, not only of a very distinct race being established 'per saltum', but of that race breeding "true" at once, and showing no mixed forms, even when crossed with another breed. By taking care to select Ancons of both sexes, for breeding from, it thus became easy to establish an extremely well-marked race; so peculiar that, even when herded with other sheep, it was noted that the Ancons kept together. And there is every reason to believe that the existence of this breed might have been indefinitely protracted; but the introduction of the Merino sheep, which were not only very superior to the Ancons in wool and meat, but quite as quiet and orderly, led to the complete neglect of the new breed, so that, in 1813, Colonel Humphreys found it difficult to obtain the specimen, whose skeleton was presented to Sir Joseph Banks. We believe that, for many years, no remnant of it has existed in the United States. Gratio Kelleia was not the progenitor of a race of six-fingered men, as Seth Wright's ram became a nation of Ancon sheep, though the tendency of the variety to perpetuate itself appears to have been fully as strong in the one case as in the other. And the reason of the difference is not far to seek. Seth Wright took care not to weaken the Ancon blood by matching his Ancon ewes with any but males of the same variety, while Gratio Kelleia's sons were too far removed from the patriarchal times to intermarry with their sisters; and his grandchildren seem not to have been attracted by their six-fingered cousins. In other words, in the one example a race was produced, because, for several generations, care was taken to 'select' both parents of the breeding stock from animals exhibiting a tendency to vary in the same condition; while, in the other, no race was evolved, because no such selection was exercised. A race is a propagated variety; and as, by the laws of reproduction, offspring tend to assume the parental forms, they will be more likely to propagate a variation exhibited by both parents than that possessed by only one. There is no organ of the body of an animal which may not, and does not, occasionally, vary more or less from the normal type; and there is no variation which may not be transmitted and which, if selectively transmitted, may not become the foundation of a race. This great truth, sometimes forgotten by philosophers, has long been familiar to practical agriculturists and breeders; and upon it rest all the methods of improving the breeds of domestic animals, which, for the last century, have been followed with so much success in England. Colour, form, size, texture of hair or wool, proportions of various parts, strength or weakness of constitution, tendency to fatten or to remain lean, to give much or little milk, speed, strength, temper, intelligence, special instincts; there is not one of these characters whose transmission is not an every-day occurrence within the experience of cattle-breeders, stock-farmers, horse-dealers, and dog and poultry fanciers. Nay, it is only the other day that an eminent physiologist, Dr. Brown-Sequard, communicated to the Royal Society his discovery that epilepsy, artificially produced in guinea-pigs, by a means which he has discovered, is transmitted to their offspring. But a race, once produced, is no more a fixed and immutable entity than the stock whence it sprang; variations arise among its members, and as these variations are transmitted like any others, new races may be developed out of the pre-existing one 'ad infinitum', or, at least, within any limit at present determined. Given sufficient time and sufficiently careful selection, and the multitude of races which may arise from a common stock is as astonishing as are the extreme structural differences which they may present. A remarkable example of this is to be found in the rock-pigeon, which Dr. Darwin has, in our opinion, satisfactorily demonstrated to be the progenitor of all our domestic pigeons, of which there are certainly more than a hundred well-marked races. The most noteworthy of these races are, the four great stocks known to the "fancy" as tumblers, pouters, carriers, and fantails; birds which not only differ most singularly in size, colour, and habits, but in the form of the beak and of the skull: in the proportions of the beak to the skull; in the number of tail-feathers; in the absolute and relative size of the feet; in the presence or absence of the uropygial gland; in the number of vertebrae in the back; in short, in precisely those characters in which the genera and species of birds differ from one another. And it is most remarkable and instructive to observe, that none of these races can be shown to have been originated by the action of changes in what are commonly called external circumstances, upon the wild rock-pigeon. On the contrary, from time immemorial, pigeon-fanciers have had essentially similar methods of treating their pets, which have been housed, fed, protected and cared for in much the same way in all pigeonries. In fact, there is no case better adapted than that of the pigeons to refute the doctrine which one sees put forth on high authority, that "no other characters than those founded on the development of bone for the attachment of muscles" are capable of variation. In precise contradiction of this hasty assertion, Mr. Darwin's researches prove that the skeleton of the wings in domestic pigeons has hardly varied at all from that of the wild type; while, on the other hand, it is in exactly those respects, such as the relative length of the beak and skull, the number of the vertebrae, and the number of the tail-feathers, in which muscular exertion can have no important influence, that the utmost amount of variation has taken place. We have said that the following out of the properties exhibited by physiological species would lead us into difficulties, and at this point they begin to be obvious; for if, as the result of spontaneous variation and of selective breeding, the progeny of a common stock may become separated into groups distinguished from one another by constant, not sexual, morphological characters, it is clear that the physiological definition of species is likely to clash with the morphological definition. No one would hesitate to describe the pouter and the tumbler as distinct species, if they were found fossil, or if their skins and skeletons were imported, as those of exotic wild birds commonly are--and without doubt, if considered alone, they are good and distinct morphological species. On the other hand, they are not physiological species, for they are descended from a common stock, the rock-pigeon. Under these circumstances, as it is admitted on all sides that races occur in Nature, how are we to know whether any apparently distinct animals are really of different physiological species, or not, seeing that the amount of morphological difference is no safe guide? Is there any test of a physiological species? The usual answer of physiologists is in the affirmative. It is said that such a test is to be found in the phenomena of hybridization--in the results of crossing races, as compared with the results of crossing species. So far as the evidence goes at present, individuals, of what are certainly known to be mere races produced by selection, however distinct they may appear to be, not only breed freely together, but the offspring of such crossed races are only perfectly fertile with one another. Thus, the spaniel and the greyhound, the dray-horse and the Arab, the pouter and the tumbler, breed together with perfect freedom, and their mongrels, if matched with other mongrels of the same kind, are equally fertile. On the other hand, there can be no doubt that the individuals of many natural species are either absolutely infertile if crossed with individuals of other species, or, if they give rise to hybrid offspring, the hybrids so produced are infertile when paired together. The horse and the ass, for instance, if so crossed, give rise to the mule, and there is no certain evidence of offspring ever having been produced by a male and female mule. The unions of the rock-pigeon and the ring-pigeon appear to be equally barren of result. Here, then, says the physiologist, we have a means of distinguishing any two true species from any two varieties. If a male and a female, selected from each group, produce offspring, and that offspring is fertile with others produced in the same way, the groups are races and not species. If, on the other hand, no result ensues, or if the offspring are infertile with others produced in the same way, they are true physiological species. The test would be an admirable one, if, in the first place, it were always practicable to apply it, and if, in the second, it always yielded results susceptible of a definite interpretation. Unfortunately, in the great majority of cases, this touchstone for species is wholly inapplicable. The constitution of many wild animals is so altered by confinement that they will not breed even with their own females, so that the negative results obtained from crosses are of no value; and the antipathy of wild animals of the same species for one another, or even of wild and tame members of the same species, is ordinarily so great, that it is hopeless to look for such unions in Nature. The hermaphrodism of most plants, the difficulty in the way of insuring the absence of their own, or the proper working of other pollen, are obstacles of no less magnitude in applying the test to them. And, in both animals and plants, is superadded the further difficulty, that experiments must be continued over a long time for the purpose of ascertaining the fertility of the mongrel or hybrid progeny, as well as of the first crosses from which they spring. Not only do these great practical difficulties lie in the way of applying the hybridization test, but even when this oracle can be questioned, its replies are sometimes as doubtful as those of Delphi. For example, cases are cited by Mr. Darwin, of plants which are more fertile with the pollen of another species than with their own; and there are others, such as certain 'fuci', whose male element will fertilize the ovule of a plant of distinct species, while the males of the latter species are ineffective with the females of the first. So that, in the last-named instance, a physiologist, who should cross the two species in one way, would decide that they were true species; while another, who should cross them in the reverse way, would, with equal justice, according to the rule, pronounce them to be mere races. Several plants, which there is great reason to believe are mere varieties, are almost sterile when crossed; while both animals and plants, which have always been regarded by naturalists as of distinct species, turn out, when the test is applied, to be perfectly fertile. Again, the sterility or fertility of crosses seems to bear no relation to the structural resemblances or differences of the members of any two groups. Mr. Darwin has discussed this question with singular ability and circumspection, and his conclusions are summed up as follows, at page 276 of his work:-- "First crosses between forms sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile. The sterility is of all degrees, and is often so slight that the two most careful experimentalists who have ever lived have come to diametrically opposite conclusions in ranking forms by this test. The sterility is innately variable in individuals of the same species, and is eminently susceptible of favourable and unfavourable conditions. The degree of sterility does not strictly follow systematic affinity, but is governed by several curious and complex laws. It is generally different and sometimes widely different, in reciprocal crosses between the same two species. It is not always equal in degree in a first cross, and in the hybrid produced from this cross. "In the same manner as in grafting trees, the capacity of one species or variety to take on another is incidental on generally unknown differences in their vegetative systems; so in crossing, the greater or less facility of one species to unite with another is incidental on unknown differences in their reproductive systems. There is no more reason to think that species have been specially endowed with various degrees of sterility to prevent them crossing and breeding in Nature, than to think that trees have been specially endowed with various and somewhat analogous degrees of difficulty in being grafted together, in order to prevent them becoming inarched in our forests. "The sterility of first crosses between pure species, which have their reproductive systems perfect, seems to depend on several circumstances; in some cases largely on the early death of the embryo. The sterility of hybrids which have their reproductive systems imperfect, and which have had this system and their whole organization disturbed by being compounded of two distinct species, seems closely allied to that sterility which so frequently affects pure species when their natural conditions of life have been disturbed. This view is supported by a parallelism of another kind: namely, that the crossing of forms, only slightly different, is favourable to the vigour and fertility of the offspring; and that slight changes in the conditions of life are apparently favourable to the vigour and fertility of all organic beings. It is not surprising that the degree of difficulty in uniting two species, and the degree of sterility of their hybrid offspring, should generally correspond, though due to distinct causes; for both depend on the amount of difference of some kind between the species which are crossed. Nor is it surprising that the facility of effecting a first cross, the fertility of hybrids produced from it, and the capacity of being grafted together--though this latter capacity evidently depends on widely different circumstances--should all run to a certain extent parallel with the systematic affinity of the forms which are subjected to experiment; for systematic affinity attempts to express all kinds of resemblance between all species. "First crosses between forms known to be varieties, or sufficiently alike to be considered as varieties, and their mongrel offspring, are very generally, but not quite universally, fertile. Nor is this nearly general and perfect fertility surprising, when we remember how liable we are to argue in a circle with respect to varieties in a state of Nature; and when we remember that the greater number of varieties have been produced under domestication by the selection of mere external differences, and not of differences in the reproductive system. In all other respects, excluding fertility, there is a close general resemblance between hybrids and mongrels."--Pp. 276-8. We fully agree with the general tenor of this weighty passage; but forcible as are these arguments, and little as the value of fertility or infertility as a test of species may be, it must not be forgotten that the really important fact, so far as the inquiry into the origin of species goes, is, that there are such things in Nature as groups of animals and of plants, whose members are incapable of fertile union with those of other groups; and that there are such things as hybrids, which are absolutely sterile when crossed with other hybrids. For, if such phenomena as these were exhibited by only two of those assemblages of living objects, to which the name of species (whether it be used in its physiological or in its morphological sense) is given, it would have to be accounted for by any theory of the origin of species, and every theory which could not account for it would be, so far, imperfect. Up to this point, we have been dealing with matters of fact, and the statements which we have laid before the reader would, to the best of our knowledge, be admitted to contain a fair exposition of what is at present known respecting the essential properties of species, by all who have studied the question. And whatever may be his theoretical views, no naturalist will probably be disposed to demur to the following summary of that exposition:-- Living beings, whether animals or plants, are divisible into multitudes of distinctly definable kinds, which are morphological species. They are also divisible into groups of individuals, which breed freely together, tending to reproduce their like, and are physiological species. Normally resembling their parents, the offspring of members of these species are still liable to vary; and the variation may be perpetuated by selection, as a race, which race, in many cases, presents all the characteristics of a morphological species. But it is not as yet proved that a race ever exhibits, when crossed with another race of the same species, those phenomena of hybridization which are exhibited by many species when crossed with other species. On the other hand, not only is it not proved that all species give rise to hybrids infertile 'inter se', but there is much reason to believe that, in crossing, species exhibit every gradation from perfect sterility to perfect fertility. Such are the most essential characteristics of species. Even were man not one of them--a member of the same system and subject to the same laws--the question of their origin, their causal connexion, that is, with the other phenomena of the universe, must have attracted his attention, as soon as his intelligence had raised itself above the level of his daily wants. Indeed history relates that such was the case, and has embalmed for us the speculations upon the origin of living beings, which were among the earliest products of the dawning intellectual activity of man. In those early days positive knowledge was not to be had, but the craving after it needed, at all hazards, to be satisfied, and according to the country, or the turn of thought, of the speculator, the suggestion that all living things arose from the mud of the Nile, from a primeval egg, or from some more anthropomorphic agency, afforded a sufficient resting-place for his curiosity. The myths of Paganism are as dead as Osiris or Zeus, and the man who should revive them, in opposition to the knowledge of our time, would be justly laughed to scorn; but the coeval imaginations current among the rude inhabitants of Palestine, recorded by writers whose very name and age are admitted by every scholar to be unknown, have unfortunately not yet shared their fate, but, even at this day, are regarded by nine-tenths of the civilized world as the authoritative standard of fact and the criterion of the justice of scientific conclusions, in all that relates to the origin of things, and, among them, of species. In this nineteenth century, as at the dawn of modern physical science, the cosmogony of the semi-barbarous Hebrew is the incubus of the philosopher and the opprobrium of the orthodox. Who shall number the patient and earnest seekers after truth, from the days of Galileo until now, whose lives have been embittered and their good name blasted by the mistaken zeal of Bibliolaters? Who shall count the host of weaker men whose sense of truth has been destroyed in the effort to harmonize impossibilities--whose life has been wasted in the attempt to force the generous new wine of Science into the old bottles of Judaism, compelled by the outcry of the same strong party? It is true that if philosophers have suffered, their cause has been amply avenged. Extinguished theologians lie about the cradle of every science as the strangled snakes beside that of Hercules; and history records that whenever science and orthodoxy have been fairly opposed, the latter has been forced to retire from the lists, bleeding and crushed if not annihilated; scotched, if not slain. But orthodoxy is the Bourbon of the world of thought. It learns not, neither can it forget; and though, at present, bewildered and afraid to move, it is as willing as ever to insist that the first chapter of Genesis contains the beginning and the end of sound science; and to visit, with such petty thunderbolts as its half-paralysed hands can hurl, those who refuse to degrade Nature to the level of primitive Judaism. Philosophers, on the other hand, have no such aggressive tendencies. With eyes fixed on the noble goal to which "per aspera et ardua" they tend, they may, now and then, be stirred to momentary wrath by the unnecessary obstacles with which the ignorant, or the malicious, encumber, if they cannot bar, the difficult path; but why should their souls be deeply vexed? The majesty of Fact is on their side, and the elemental forces of Nature are working for them. Not a star comes to the meridian at its calculated time but testifies to the justice of their methods--their beliefs are "one with falling rain and with the growing corn." By doubt they are established, and open inquiry is their bosom friend. Such men have no fear of traditions however venerable, and no respect for them when they become mischievous and obstructive; but they have better than mere antiquarian business in hand, and if dogmas, which ought to be fossil but are not, are not forced upon their notice, they are too happy to treat them as non-existent. The hypotheses respecting the origin of species which profess to stand upon a scientific basis, and, as such, alone demand serious attention, are of two kinds. The one, the "special creation" hypothesis, presumes every species to have originated from one or more stocks, these not being the result of the modification of any other form of living matter--or arising by natural agencies--but being produced, as such, by a supernatural creative act. The other, the so-called "transmutation" hypothesis, considers that all existing species are the result of the modification of pre-existing species, and those of their predecessors, by agencies similar to those which at the present day produce varieties and races, and therefore in an altogether natural way; and it is a probable, though not a necessary consequence of this hypothesis, that all living beings have arisen from a single stock. With respect to the origin of this primitive stock, or stocks, the doctrine of the origin of species is obviously not necessarily concerned. The transmutation hypothesis, for example, is perfectly consistent either with the conception of a special creation of the primitive germ, or with the supposition of its having arisen, as a modification of inorganic matter, by natural causes. The doctrine of special creation owes its existence very largely to the supposed necessity of making science accord with the Hebrew cosmogony; but it is curious to observe that, as the doctrine is at present maintained by men of science, it is as hopelessly inconsistent with the Hebrew view as any other hypothesis. If there be any result which has come more clearly out of geological investigation than another, it is, that the vast series of extinct animals and plants is not divisible, as it was once supposed to be, into distinct groups, separated by sharply-marked boundaries. There are no great gulfs between epochs and formations--no successive periods marked by the appearance of plants, of water animals, and of land animals, 'en masse'. Every year adds to the list of links between what the older geologists supposed to be widely separated epochs: witness the crags linking the drift with older tertiaries; the Maestricht beds linking the tertiaries with the chalk; the St. Cassian beds exhibiting an abundant fauna of mixed mesozoic and palaeozoic types, in rocks of an epoch once supposed to be eminently poor in life; witness, lastly, the incessant disputes as to whether a given stratum shall be reckoned devonian or carboniferous, silurian or devonian, cambrian or silurian. This truth is further illustrated in a most interesting manner by the impartial and highly competent testimony of M. Pictet, from whose calculations of what percentage of the genera of animals, existing in any formation, lived during the preceding formation, it results that in no case is the proportion less than 'one-third', or 33 per cent. It is the triassic formation, or the commencement of the mesozoic epoch, which has received the smallest inheritance from preceding ages. The other formations not uncommonly exhibit 60, 80, or even 94 per cent. of genera in common with those whose remains are imbedded in their predecessor. Not only is this true, but the subdivisions of each formation exhibit new species characteristic of, and found only in, them; and, in many cases, as in the lias for example, the separate beds of these subdivisions are distinguished by well-marked and peculiar forms of life. A section, a hundred feet thick, will exhibit, at different heights, a dozen species of ammonite, none of which passes beyond its particular zone of limestone, or clay, into the zone below it or into that above it; so that those who adopt the doctrine of special creation must be prepared to admit, that at intervals of time, corresponding with the thickness of these beds, the Creator thought fit to interfere with the natural course of events for the purpose of making a new ammonite. It is not easy to transplant oneself into the frame of mind of those who can accept such a conclusion as this, on any evidence short of absolute demonstration; and it is difficult to see what is to be gained by so doing, since, as we have said, it is obvious that such a view of the origin of living beings is utterly opposed to the Hebrew cosmogony. Deserving no aid from the powerful arm of Bibliolatry, then, does the received form of the hypothesis of special creation derive any support from science or sound logic? Assuredly not much. The arguments brought forward in its favour all take one form: If species were not supernaturally created, we cannot understand the facts 'x' or 'y', or 'z'; we cannot understand the structure of animals or plants, unless we suppose they were contrived for special ends; we cannot understand the structure of the eye, except by supposing it to have been made to see with; we cannot understand instincts, unless we suppose animals to have been miraculously endowed with them. As a question of dialectics, it must be admitted that this sort of reasoning is not very formidable to those who are not to be frightened by consequences. It is an 'argumentum ad ignorantiam'--take this explanation or be ignorant. But suppose we prefer to admit our ignorance rather than adopt a hypothesis at variance with all the teachings of Nature? Or, suppose for a moment we admit the explanation, and then seriously ask ourselves how much the wiser are we; what does the explanation explain? Is it any more than a grandiloquent way of announcing the fact, that we really know nothing about the matter? A phenomenon is explained when it is shown to be a case of some general law of Nature; but the supernatural interposition of the Creator can, by the nature of the case, exemplify no law, and if species have really arisen in this way, it is absurd to attempt to discuss their origin. Or, lastly, let us ask ourselves whether any amount of evidence which the nature of our faculties permits us to attain, can justify us in asserting that any phenomenon is out of the reach of natural causation. To this end it is obviously necessary that we should know all the consequences to which all possible combinations, continued through unlimited time, can give rise. If we knew these, and found none competent to originate species, we should have good ground for denying their origin by natural causation. Till we know them, any hypothesis is better than one which involves us in such miserable presumption. But the hypothesis of special creation is not only a mere specious mask for our ignorance; its existence in Biology marks the youth and imperfection of the science. For what is the history of every science but the history of the elimination of the notion of creative, or other interferences, with the natural order of the phenomena which are the subject-matter of that science? When Astronomy was young "the morning stars sang together for joy," and the planets were guided in their courses by celestial hands. Now, the harmony of the stars has resolved itself into gravitation according to the inverse squares of the distances, and the orbits of the planets are deducible from the laws of the forces which allow a schoolboy's stone to break a window. The lightning was the angel of the Lord; but it has pleased Providence, in these modern times, that science should make it the humble messenger of man, and we know that every flash that shimmers about the horizon on a summer's evening is determined by ascertainable conditions, and that its direction and brightness might, if our knowledge of these were great enough, have been calculated. The solvency of great mercantile companies rests on the validity of the laws which have been ascertained to govern the seeming irregularity of that human life which the moralist bewails as the most uncertain of things; plague, pestilence, and famine are admitted, by all but fools, to be the natural result of causes for the most part fully within human control, and not the unavoidable tortures inflicted by wrathful Omnipotence upon His helpless handiwork. Harmonious order governing eternally continuous progress--the web and woof of matter and force interweaving by slow degrees, without a broken thread, that veil which lies between us and the Infinite--that universe which alone we know or can know; such is the picture which science draws of the world, and in proportion as any part of that picture is in unison with the rest, so may we feel sure that it is rightly painted. Shall Biology alone remain out of harmony with her sister sciences? Such arguments against the hypothesis of the direct creation of species as these are plainly enough deducible from general considerations; but there are, in addition, phenomena exhibited by species themselves, and yet not so much a part of their very essence as to have required earlier mention, which are in the highest degree perplexing, if we adopt the popularly accepted hypothesis. Such are the facts of distribution in space and in time; the singular phenomena brought to light by the study of development; the structural relations of species upon which our systems of classification are founded; the great doctrines of philosophical anatomy, such as that of homology, or of the community of structural plan exhibited by large groups of species differing very widely in their habits and functions. The species of animals which inhabit the sea on opposite sides of the isthmus of Panama are wholly distinct [4] the animals and plants which inhabit islands are commonly distinct from those of the neighbouring mainlands, and yet have a similarity of aspect. The mammals of the latest tertiary epoch in the Old and New Worlds belong to the same genera, or family groups, as those which now inhabit the same great geographical area. The crocodilian reptiles which existed in the earliest secondary epoch were similar in general structure to those now living, but exhibit slight differences in their vertebrae, nasal passages, and one or two other points. The guinea-pig has teeth which are shed before it is born, and hence can never subserve the masticatory purpose for which they seem contrived, and, in like manner, the female dugong has tusks which never cut the gum. All the members of the same great group run through similar conditions in their development, and all their parts, in the adult state, are arranged according to the same plan. Man is more like a gorilla than a gorilla is like a lemur. Such are a few, taken at random, among the multitudes of similar facts which modern research has established; but when the student seeks for an explanation of them from the supporters of the received hypothesis of the origin of species, the reply he receives is, in substance, of Oriental simplicity and brevity--"Mashallah! it so pleases God!" There are different species on opposite sides of the isthmus of Panama, because they were created different on the two sides. The pliocene mammals are like the existing ones, because such was the plan of creation; and we find rudimental organs and similarity of plan, because it has pleased the Creator to set before Himself a "divine exemplar or archetype," and to copy it in His works; and somewhat ill, those who hold this view imply, in some of them. That such verbal hocus-pocus should be received as science will one day be regarded as evidence of the low state of intelligence in the nineteenth century, just as we amuse ourselves with the phraseology about Nature's abhorrence of a vacuum, wherewith Torricelli's compatriots were satisfied to explain the rise of water in a pump. And be it recollected that this sort of satisfaction works not only negative but positive ill, by discouraging inquiry, and so depriving man of the usufruct of one of the most fertile fields of his great patrimony, Nature. The objections to the doctrine of the origin of species by special creation which have been detailed, must have occurred, with more or less force, to the mind of every one who has seriously and independently considered the subject. It is therefore no wonder that, from time to time, this hypothesis should have been met by counter hypotheses, all as well, and some better founded than itself; and it is curious to remark that the inventors of the opposing views seem to have been led into them as much by their knowledge of geology, as by their acquaintance with biology. In fact, when the mind has once admitted the conception of the gradual production of the present physical state of our globe, by natural causes operating through long ages of time, it will be little disposed to allow that living beings have made their appearance in another way, and the speculations of De Maillet and his successors are the natural complement of Scilla's demonstration of the true nature of fossils. A contemporary of Newton and of Leibnitz, sharing therefore in the intellectual activity of the remarkable age which witnessed the birth of modern physical science, Benoit de Maillet spent a long life as a consular agent of the French Government in various Mediterranean ports. For sixteen years, in fact, he held the office of Consul-General in Egypt, and the wonderful phenomena offered by the valley of the Nile appear to have strongly impressed his mind, to have directed his attention to all facts of a similar order which came within his observation, and to have led him to speculate on the origin of the present condition of our globe and of its inhabitants. But, with all his ardour for science, De Maillet seems to have hesitated to publish views which, notwithstanding the ingenious attempts to reconcile them with the Hebrew hypothesis contained in the preface to "Telliamed," were hardly likely to be received with favour by his contemporaries. But a short time had elapsed since more than one of the great anatomists and physicists of the Italian school had paid dearly for their endeavours to dissipate some of the prevalent errors; and their illustrious pupil, Harvey, the founder of modern physiology, had not fared so well, in a country less oppressed by the benumbing influences of theology, as to tempt any man to follow his example. Probably not uninfluenced by these considerations, his Catholic majesty's Consul-General for Egypt kept his theories to himself throughout a long life, for 'Telliamed,' the only scientific work which is known to have proceeded from his pen, was not printed till 1735, when its author had reached the ripe age of seventy-nine; and though De Maillet lived three years longer, his book was not given to the world before 1748. Even then it was anonymous to those who were not in the secret of the anagrammatic character of its title; and the preface and dedication are so worded as, in case of necessity, to give the printer a fair chance of falling back on the excuse that the work was intended for a mere 'jeu d'esprit'. The speculations of the suppositious Indian sage, though quite as sound as those of many a "Mosaic Geology," which sells exceedingly well, have no great value if we consider them by the light of modern science. The waters are supposed to have originally covered the whole globe; to have deposited the rocky masses which compose its mountains by processes comparable to those which are now forming mud, sand, and shingle; and then to have gradually lowered their level, leaving the spoils of their animal and vegetable inhabitants embedded in the strata. As the dry land appeared, certain of the aquatic animals are supposed to have taken to it, and to have become gradually adapted to terrestrial and aerial modes of existence. But if we regard the general tenor and style of the reasoning in relation to the state of knowledge of the day, two circumstances appear very well worthy of remark. The first, that De Maillet had a notion of the modifiability of living forms (though without any precise information on the subject), and how such modifiability might account for the origin of species; the second, that he very clearly apprehended the great modern geological doctrine, so strongly insisted upon by Hutton, and so ably and comprehensively expounded by Lyell, that we must look to existing causes for the explanation of past geological events. Indeed, the following passage of the preface, in which De Maillet is supposed to speak of the Indian philosopher Telliamed, his 'alter ego', might have been written by the most philosophical uniformitarian of the present day:-- "Ce qu'il y a d'etonnant, est que pour arriver a ces connoissances il semble avoir perverti l'ordre naturel, puisqu'au lieu de s'attacher d'abord a rechercher l'origine de notre globe il a commence par travailler a s'instruire de la nature. Mais a l'entendre, ce renversement de l'ordre a ete pour lui l'effet d'un genie favorable qui l'a conduit pas a pas et comme par la main aux decouvertes les plus sublimes. C'est en decomposant la substance de ce globe par une anatomie exacte de toutes ses parties qu'il a premierement appris de quelles matieres il etait compose et quels arrangemens ces memes matieres observaient entre elles. Ces lumieres jointes a l'esprit de comparaison toujours necessaire a quiconque entreprend de percer les voiles dont la nature aime a se cacher, ont servi de guide a notre philosophe pour parvenir a des connoissances plus interessantes. Par la matiere et l'arrangement de ces compositions il pretend avoir reconnu quelle est la veritable origine de ce globe que nous habitons, comment et par qui il a ete forme."--Pp. xix. xx. But De Maillet was before his age, and as could hardly fail to happen to one who speculated on a zoological and botanical question before Linnaeus, and on a physiological problem before Haller, he fell into great errors here and there; and hence, perhaps, the general neglect of his work. Robinet's speculations are rather behind, than in advance of, those of De Maillet; and though Linnaeus may have played with the hypothesis of transmutation, it obtained no serious support until Lamarck adopted it, and advocated it with great ability in his 'Philosophie Zoologique.' Impelled towards the hypothesis of the transmutation of species, partly by his general cosmological and geological views; partly by the conception of a graduated, though irregularly branching, scale of being, which had arisen out of his profound study of plants and of the lower forms of animal life, Lamarck, whose general line of thought often closely resembles that of De Maillet, made a great advance upon the crude and merely speculative manner in which that writer deals with the question of the origin of living beings, by endeavouring to find physical causes competent to effect that change of one species into another, which De Maillet had only supposed to occur. And Lamarck conceived that he had found in Nature such causes, amply sufficient for the purpose in view. It is a physiological fact, he says, that organs are increased in size by action, atrophied by inaction; it is another physiological fact that modifications produced are transmissible to offspring. Change the actions of an animal, therefore, and you will change its structure, by increasing the development of the parts newly brought into use and by the diminution of those less used; but by altering the circumstances which surround it you will alter its actions, and hence, in the long run, change of circumstance must produce change of organization. All the species of animals, therefore, are, in Lamarck's view, the result of the indirect action of changes of circumstance, upon those primitive germs which he considered to have originally arisen, by spontaneous generation, within the waters of the globe. It is curious, however, that Lamarck should insist so strongly [5] as he has done, that circumstances never in any degree directly modify the form or the organization of animals, but only operate by changing their wants and consequently their actions; for he thereby brings upon himself the obvious question, how, then, do plants, which cannot be said to have wants or actions, become modified? To this he replies, that they are modified by the changes in their nutritive processes, which are effected by changing circumstances; and it does not seem to have occurred to him that such changes might be as well supposed to take place among animals. When we have said that Lamarck felt that mere speculation was not the way to arrive at the origin of species, but that it was necessary, in order to the establishment of any sound theory on the subject, to discover by observation or otherwise, some 'vera causa', competent to give rise to them; that he affirmed the true order of classification to coincide with the order of their development one from another; that he insisted on the necessity of allowing sufficient time, very strongly; and that all the varieties of instinct and reason were traced back by him to the same cause as that which has given rise to species, we have enumerated his chief contributions to the advance of the question. On the other hand, from his ignorance of any power in Nature competent to modify the structure of animals, except the development of parts, or atrophy of them, in consequence of a change of needs, Lamarck was led to attach infinitely greater weight than it deserves to this agency, and the absurdities into which he was led have met with deserved condemnation. Of the struggle for existence, on which, as we shall see, Mr. Darwin lays such great stress, he had no conception; indeed, he doubts whether there really are such things as extinct species, unless they be such large animals as may have met their death at the hands of man; and so little does he dream of there being any other destructive causes at work, that, in discussing the possible existence of fossil shells, he asks, "Pourquoi d'ailleurs seroient-ils perdues des que l'homme n'a pu operer leur destruction?" ('Phil. Zool.,' vol. i. p. 77.) Of the influence of selection Lamarck has as little notion, and he makes no use of the wonderful phenomena which are exhibited by domesticated animals, and illustrate its powers. The vast influence of Cuvier was employed against the Lamarckian views, and, as the untenability of some of his conclusions was easily shown, his doctrines sank under the opprobrium of scientific, as well as of theological, heterodoxy. Nor have the efforts made of late years to revive them tended to re-establish their credit in the minds of sound thinkers acquainted with the facts of the case; indeed it may be doubted whether Lamarck has not suffered more from his friends than from his foes. Two years ago, in fact, though we venture to question if even the strongest supporters of the special creation hypothesis had not, now and then, an uneasy consciousness that all was not right, their position seemed more impregnable than ever, if not by its own inherent strength, at any rate by the obvious failure of all the attempts which had been made to carry it. On the other hand, however much the few, who thought deeply on the question of species, might be repelled by the generally received dogmas, they saw no way of escaping from them save by the adoption of suppositions so little justified by experiment or by observation as to be at least equally distasteful. The choice lay between two absurdities and a middle condition of uneasy scepticism; which last, however unpleasant and unsatisfactory, was obviously the only justifiable state of mind under the circumstances. Such being the general ferment in the minds of naturalists, it is no wonder that they mustered strong in the rooms of the Linnaean Society, on the 1st of July of the year 1858, to hear two papers by authors living on opposite sides of the globe, working out their results independently, and yet professing to have discovered one and the same solution of all the problems connected with species. The one of these authors was an able naturalist, Mr. Wallace, who had been employed for some years in studying the productions of the islands of the Indian Archipelago, and who had forwarded a memoir embodying his views to Mr. Darwin, for communication to the Linnaean Society. On perusing the essay, Mr. Darwin was not a little surprised to find that it embodied some of the leading ideas of a great work which he had been preparing for twenty years, and parts of which, containing a development of the very same views, had been perused by his private friends fifteen or sixteen years before. Perplexed in what manner to do full justice both to his friend and to himself, Mr. Darwin placed the matter in the hands of Dr. Hooker and Sir Charles Lyell, by whose advice he communicated a brief abstract of his own views to the Linnaean Society, at the same time that Mr. Wallace's paper was read. Of that abstract, the work on the 'Origin of Species' is an enlargement; but a complete statement of Mr. Darwin's doctrine is looked for in the large and well-illustrated work which he is said to be preparing for publication. The Darwinian hypothesis has the merit of being eminently simple and comprehensible in principle, and its essential positions may be stated in a very few words: all species have been produced by the development of varieties from common stocks; by the conversion of these, first into permanent races and then into new species, by the process of 'natural selection', which process is essentially identical with that artificial selection by which man has originated the races of domestic animals--the 'struggle for existence' taking the place of man, and exerting, in the case of natural selection, that selective action which he performs in artificial selection. The evidence brought forward by Mr. Darwin in support of his hypothesis is of three kinds. First, he endeavours to prove that species may be originated by selection; secondly, he attempts to show that natural causes are competent to exert selection; and thirdly, he tries to prove that the most remarkable and apparently anomalous phenomena exhibited by the distribution, development, and mutual relations of species, can be shown to be deducible from the general doctrine of their origin, which he propounds, combined with the known facts of geological change; and that, even if all these phenomena are not at present explicable by it, none are necessarily inconsistent with it. There cannot be a doubt that the method of inquiry which Mr. Darwin has adopted is not only rigorously in accordance with the canons of scientific logic, but that it is the only adequate method. Critics exclusively trained in classics or in mathematics, who have never determined a scientific fact in their lives by induction from experiment or observation, prate learnedly about Mr. Darwin's method, which is not inductive enough, not Baconian enough, forsooth, for them. But even if practical acquaintance with the process of scientific investigation is denied them, they may learn, by the perusal of Mr. Mill's admirable chapter "On the Deductive Method," that there are multitudes of scientific inquiries in which the method of pure induction helps the investigator but a very little way. "The mode of investigation," says Mr. Mill, "which, from the proved inapplicability of direct methods of observation and experiment, remains to us as the main source of the knowledge we possess, or can acquire, respecting the conditions and laws of recurrence of the more complex phenomena, is called, in its most general expression, the deductive method, and consists of three operations: the first, one of direct induction; the second, of ratiocination; and the third, of verification." Now, the conditions which have determined the existence of species are not only exceedingly complex, but, so far as the great majority of them are concerned, are necessarily beyond our cognizance. But what Mr. Darwin has attempted to do is in exact accordance with the rule laid down by Mr. Mill; he has endeavoured to determine certain great facts inductively, by observation and experiment; he has then reasoned from the data thus furnished; and lastly, he has tested the validity of his ratiocination by comparing his deductions with the observed facts of Nature. Inductively, Mr. Darwin endeavours to prove that species arise in a given way. Deductively, he desires to show that, if they arise in that way, the facts of distribution, development, classification, etc., may be accounted for, 'i.e.' may be deduced from their mode of origin, combined with admitted changes in physical geography and climate, during an indefinite period. And this explanation, or coincidence of observed with deduced facts, is, so far as it extends, a verification of the Darwinian view. There is no fault to be found with Mr. Darwin's method, then; but it is another question whether he has fulfilled all the conditions imposed by that method. Is it satisfactorily proved, in fact, that species may be originated by selection? that there is such a thing as natural selection? that none of the phenomena exhibited by species are inconsistent with the origin of species in this way? If these questions can be answered in the affirmative, Mr. Darwin's view steps out of the rank of hypotheses into those of proved theories; but, so long as the evidence at present adduced falls short of enforcing that affirmation, so long, to our minds, must the new doctrine be content to remain among the former--an extremely valuable, and in the highest degree probable, doctrine, indeed the only extant hypothesis which is worth anything in a scientific point of view; but still a hypothesis, and not yet the theory of species. After much consideration, and with assuredly no bias against Mr. Darwin's views, it is our clear conviction that, as the evidence stands, it is not absolutely proven that a group of animals, having all the characters exhibited by species in Nature, has ever been originate by selection, whether artificial or natural. Groups having the morphological character of species, distinct and permanent races in fact, have been so produced over and over again; but there is no positive evidence, at present, that any group of animals has, by variation and selective breeding, given rise to another group which was, even in the least degree, infertile with the first. Mr. Darwin is perfectly aware of this weak point, and brings forward a multitude of ingenious and important arguments to diminish the force of the objection. We admit the value of these arguments to their fullest extent; nay, we will go so far as to express our belief that experiments, conducted by a skilful physiologist, would very probably obtain the desired production of mutually more or less infertile breeds from a common stock, in a comparatively few years; but still, as the case stands at present, this "little rift within the lute" is not to be disguised nor overlooked. In the remainder of Mr. Darwin's argument our own private ingenuity has not hitherto enabled us to pick holes of any great importance; and judging by what we hear and read, other adventurers in the same field do not seem to have been much more fortunate. It has been urged, for instance, that in his chapters on the struggle for existence and on natural selection, Mr. Darwin does not so much prove that natural selection does occur, as that it must occur; but, in fact, no other sort of demonstration is attainable. A race does not attract our attention in Nature until it has, in all probability, existed for a considerable time, and then it is too late to inquire into the conditions of its origin. Again, it is said that there is no real analogy between the selection which takes place under domestication, by human influence, and any operation which can be effected by Nature, for man interferes intelligently. Reduced to its elements, this argument implies that an effect produced with trouble by an intelligent agent must, 'a fortiori', be more troublesome, if not impossible, to an unintelligent agent. Even putting aside the question whether Nature, acting as she does according to definite and invariable laws, can be rightly called an unintelligent agent, such a position as this is wholly untenable. Mix salt and sand, and it shall puzzle the wisest of men, with his mere natural appliances, to separate all the grains of sand from all the grains of salt; but a shower of rain will effect the same object in ten minutes. And so, while man may find it tax all his intelligence to separate any variety which arises, and to breed selectively from it, the destructive agencies incessantly at work in Nature, if they find one variety to be more soluble in circumstances than the other, will inevitably, in the long run, eliminate it. A frequent and a just objection to the Lamarckian hypothesis of the transmutation of species is based upon the absence of transitional forms between many species. But against the Darwinian hypothesis this argument has no force. Indeed, one of the most valuable and suggestive parts of Mr. Darwin's work is that in which he proves, that the frequent absence of transitions is a necessary consequence of his doctrine, and that the stock whence two or more species have sprung, need in no respect be intermediate between these species. If any two species have arisen from a common stock in the same way as the carrier and the pouter, say, have arisen from the rock-pigeon, then the common stock of these two species need be no more intermediate between the two than the rock-pigeon is between the carrier and pouter. Clearly appreciate the force of this analogy, and all the arguments against the origin of species by selection, based on the absence of transitional forms, fall to the ground. And Mr. Darwin's position might, we think, have been even stronger than it is if he had not embarrassed himself with the aphorism, "Natura non facit saltum," which turns up so often in his pages. We believe, as we have said above, that Nature does make jumps now and then, and a recognition of the fact is of no small importance in disposing of many minor objections to the doctrine of transmutation. But we must pause. The discussion of Mr. Darwin's arguments in detail would lead us far beyond the limits within which we proposed, at starting, to confine this article. Our object has been attained if we have given an intelligible, however brief, account of the established facts connected with species, and of the relation of the explanation of those facts offered by Mr. Darwin to the theoretical views held by his predecessors and his contemporaries, and, above all, to the requirements of scientific logic. We have ventured to point out that it does not, as yet, satisfy all those requirements; but we do not hesitate to assert that it is as superior to any preceding or contemporary hypothesis, in the extent of observational and experimental basis on which it rests, in its rigorously scientific method, and in its power of explaining biological phenomena, as was the hypothesis of Copernicus to the speculations of Ptolemy. But the planetary orbits turned out to be not quite circular after all, and, grand as was the service Copernicus rendered to science, Kepler and Newton had to come after him. What if the orbit of Darwinism should be a little too circular? What if species should offer residual phenomena, here and there, not explicable by natural selection? Twenty years hence naturalists may be in a position to say whether this is, or is not, the case; but in either event they will owe the author of 'The Origin of Species' an immense debt of gratitude. We should leave a very wrong impression on the reader's mind if we permitted him to suppose that the value of that work depends wholly on the ultimate justification of the theoretical views which it contains. On the contrary, if they were disproved to-morrow, the book would still be the best of its kind--the most compendious statement of well-sifted facts bearing on the doctrine of species that has ever appeared. The chapters on Variation, on the Struggle for Existence, on Instinct, on Hybridism, on the Imperfection of the Geological Record, on Geographical Distribution, have not only no equals, but, so far as our knowledge goes, no competitors, within the range of biological literature. And viewed as a whole, we do not believe that, since the publication of Von Baer's Researches on Development, thirty years ago, any work has appeared calculated to exert so large an influence, not only on the future of Biology, but in extending the domination of Science over regions of thought into which she has, as yet, hardly penetrated. [Footnote 1: 'The Westminster Review', April 1860.] [Footnote 2: On the Osteology of the Chimpanzees and Orangs: Transactions of the Zoological Society, 1858.] [Footnote 3: Colonel Humphreys' statements are exceedingly explicit on this point:--"When an Ancon ewe is impregnated by a common ram, the increase resembles wholly either the ewe or the ram. The increase of the common ewe impregnated by an Ancon ram follows entirely the one or the other, without blending any of the distinguishing and essential peculiarities of both. Frequent instances have happened where common ewes have had twins by Ancon rams, when one exhibited the complete marks and features of the ewe, the other of the ram. The contrast has been rendered singularly striking, when one short-legged and one long-legged lamb, produced at a birth, have been seen sucking the dam at the same time."--'Philosophical Transactions', 1813, Pt. I. pp. 89, 90.] [Footnote 4: Recent investigations tend to show that this statement is not strictly accurate.--1870.] [Footnote 5: See 'Phil. Zoologique,' vol. i. p. 222, 'et seq.'] 
22764	----	Transcriber's note: A few typographical errors have been corrected: they are listed at the end of the text. * * * * * ON THE ORIGIN OF SPECIES. * * * * * "But with regard to the material world, we can at least go so far as this--we can perceive that events are brought about not by insulated interpositions of Divine power, exerted in each particular case, but by the establishment of general laws." WHEWELL: _Bridgewater Treatise_. "The only distinct meaning of the word 'natural' is _stated_, _fixed_, or _settled_; since what is natural as much requires and presupposes an intelligent agent to render it so, _i.e._ to effect it continually or at stated times, as what is supernatural or miraculous does to effect it for once." BUTLER: _Analogy of Revealed Religion_. "To conclude, therefore, let no man out of a weak conceit of sobriety, or an ill-applied moderation, think or maintain, that a man can search too far or be too well studied in the book of God's word, or in the book of God's works; divinity or philosophy; but rather let men endeavour an endless progress or proficience in both." BACON: _Advancement of Learning_. * * * * * _Down, Bromley, Kent,_ _October 1st, 1859._ (_1st Thousand_). * * * * * ON THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION, OR THE PRESERVATION OF FAVOURED RACES IN THE STRUGGLE FOR LIFE. BY CHARLES DARWIN, M.A., FELLOW OF THE ROYAL, GEOLOGICAL, LINNEAN, ETC., SOCIETIES; AUTHOR OF 'JOURNAL OF RESEARCHES DURING H. M. S. BEAGLE'S VOYAGE ROUND THE WORLD.' _FIFTH THOUSAND._ LONDON: JOHN MURRAY, ALBEMARLE STREET. 1860. _The right of Translation is reserved._ * * * * * LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET, AND CHARING CROSS. * * * * * {v} CONTENTS. * * * * * INTRODUCTION Page 1 CHAPTER I. VARIATION UNDER DOMESTICATION. Causes of Variability--Effects of Habit--Correlation of Growth--Inheritance--Character of Domestic Varieties--Difficulty of distinguishing between Varieties and Species--Origin of Domestic Varieties from one or more Species--Domestic Pigeons, their Differences and Origin--Principle of Selection anciently followed, its Effects--Methodical and Unconscious Selection--Unknown Origin of our Domestic Productions--Circumstances favourable to Man's power of Selection 7-43 CHAPTER II. VARIATION UNDER NATURE. Variability--Individual differences--Doubtful species--Wide ranging, much diffused, and common species vary most--Species of the larger genera in any country vary more than the species of the smaller genera--Many of the species of the larger genera resemble varieties in being very closely, but unequally, related to each other, and in having restricted ranges 44-59 {vi} CHAPTER III. STRUGGLE FOR EXISTENCE. Its bearing on natural selection--The term used in a wide sense--Geometrical powers of increase--Rapid increase of naturalised animals and plants--Nature of the checks to increase--Competition universal--Effects of climate--Protection from the number of individuals--Complex relations of all animals and plants throughout nature--Struggle for life most severe between individuals and varieties of the same species; often severe between species of the same genus--The relation of organism to organism the most important of all relations 60-79 CHAPTER IV. NATURAL SELECTION. Natural Selection--its power compared with man's selection--its power on characters of trifling importance--its power at all ages and on both sexes--Sexual Selection--On the generality of intercrosses between individuals of the same species--Circumstances favourable and unfavourable to Natural Selection, namely, intercrossing, isolation, number of individuals--Slow action--Extinction caused by Natural Selection--Divergence of Character, related to the diversity of inhabitants of any small area, and to naturalisation--Action of Natural Selection, through Divergence of Character and Extinction, on the descendants from a common parent--Explains the Grouping of all organic beings 80-130 CHAPTER V. LAWS OF VARIATION. Effects of external conditions--Use and disuse, combined with natural selection; organs of flight and of vision--Acclimatisation--Correlation of growth--Compensation and economy of growth--False correlations--Multiple, rudimentary, and lowly organised structures variable--Parts developed in an unusual manner are highly variable: specific characters more variable than generic: secondary sexual characters variable--Species of the same genus vary in an analogous manner--Reversions to long-lost characters--Summary 131-170 {vii} CHAPTER VI. DIFFICULTIES ON THEORY. Difficulties on the theory of descent with modification--Transitions--Absence or rarity of transitional varieties--Transitions in habits of life--Diversified habits in the same species--Species with habits widely different from those of their allies--Organs of extreme perfection--Means of transition--Cases of difficulty--Natura non facit saltum--Organs of small importance--Organs not in all cases absolutely perfect--The law of Unity of Type and of the Conditions of Existence embraced by the theory of Natural Selection 171-206 CHAPTER VII. INSTINCT. Instincts comparable with habits, but different in their origin--Instincts graduated--Aphides and ants--Instincts variable--Domestic instincts, their origin--Natural instincts of the cuckoo, ostrich, and parasitic bees--Slave-making ants--Hive-bee, its cell-making instinct--Difficulties on the theory of the Natural Selection of instincts--Neuter or sterile insects--Summary 207-244 CHAPTER VIII. HYBRIDISM. Distinction between the sterility of first crosses and of hybrids--Sterility various in degree, not universal, affected by close interbreeding, removed by domestication--Laws governing the sterility of hybrids--Sterility not a special endowment, but incidental on other differences--Causes of the sterility of first crosses and of hybrids--Parallelism between the effects of changed conditions of life and crossing--Fertility of varieties when crossed and of their mongrel offspring not universal--Hybrids and mongrels compared independently of their fertility--Summary 245-278 {viii} CHAPTER IX. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD. On the absence of intermediate varieties at the present day--On the nature of extinct intermediate varieties; on their number--On the vast lapse of time, as inferred from the rate of deposition and of denudation--On the poorness of our palæontological collections--On the intermittence of geological formations--On the absence of intermediate varieties in any one formation--On the sudden appearance of groups of species--On their sudden appearance in the lowest known fossiliferous strata 279-311 CHAPTER X. ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS. On the slow and successive appearance of new species--On their different rates of change--Species once lost do not reappear--Groups of species follow the same general rules in their appearance and disappearance as do single species--On Extinction--On simultaneous changes in the forms of life throughout the world--On the affinities of extinct species to each other and to living species--On the state of development of ancient forms--On the succession of the same types within the same areas--Summary of preceding and present chapters 312-345 CHAPTER XI. GEOGRAPHICAL DISTRIBUTION. Present distribution cannot be accounted for by differences in physical conditions--Importance of barriers--Affinity of the productions of the same continent--Centres of creation--Means of dispersal, by changes of climate and of the level of the land, and by occasional means--Dispersal during the Glacial period co-extensive with the world 346-382 CHAPTER XII. GEOGRAPHICAL DISTRIBUTION--_continued_. Distribution of fresh-water productions--On the inhabitants of oceanic islands--Absence of Batrachians and of terrestrial Mammals--On the relation of the inhabitants of islands to those of the nearest mainland--On colonisation from the nearest source with subsequent modification--Summary of the last and present chapters 383-410 CHAPTER XIII. MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY: EMBRYOLOGY: RUDIMENTARY ORGANS. CLASSIFICATION, groups subordinate to groups--Natural system--Rules and difficulties in classification, explained on the theory of descent with modification--Classification of varieties--Descent always used in classification--Analogical or adaptive characters--Affinities, general, complex and radiating--Extinction separates and defines groups--MORPHOLOGY, between members of the same class, between parts of the same individual--EMBRYOLOGY, laws of, explained by variations not supervening at an early age, and being inherited at a corresponding age--RUDIMENTARY ORGANS; their origin explained--Summary 411-458 CHAPTER XIV. RECAPITULATION AND CONCLUSION. Recapitulation of the difficulties on the theory of Natural Selection--Recapitulation of the general and special circumstances in its favour--Causes of the general belief in the immutability of species--How far the theory of natural selection may be extended--Effects of its adoption on the study of Natural history--Concluding remarks 459-490 * * * * * {1} ON THE ORIGIN OF SPECIES. * * * * * INTRODUCTION. When on board H.M.S. 'Beagle,' as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America, and in the geological relations of the present to the past inhabitants of that continent. These facts seemed to me to throw some light on the origin of species--that mystery of mysteries, as it has been called by one of our greatest philosophers. On my return home, it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work I allowed myself to speculate on the subject, and drew up some short notes; these I enlarged in 1844 into a sketch of the conclusions, which then seemed to me probable: from that period to the present day I have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision. My work is now nearly finished; but as it will take me two or three more years to complete it, and as my health is far from strong, I have been urged to publish this Abstract. I have more especially been induced to do this, as Mr. Wallace, who is now studying the {2} natural history of the Malay archipelago, has arrived at almost exactly the same general conclusions that I have on the origin of species. Last year he sent me a memoir on this subject, with a request that I would forward it to Sir Charles Lyell, who sent it to the Linnean Society, and it is published in the third volume of the Journal of that Society. Sir C. Lyell and Dr. Hooker, who both knew of my work--the latter having read my sketch of 1844--honoured me by thinking it advisable to publish, with Mr. Wallace's excellent memoir, some brief extracts from my manuscripts. This Abstract, which I now publish, must necessarily be imperfect. I cannot here give references and authorities for my several statements; and I must trust to the reader reposing some confidence in my accuracy. No doubt errors will have crept in, though I hope I have always been cautious in trusting to good authorities alone. I can here give only the general conclusions at which I have arrived, with a few facts in illustration, but which, I hope, in most cases will suffice. No one can feel more sensible than I do of the necessity of hereafter publishing in detail all the facts, with references, on which my conclusions have been grounded; and I hope in a future work to do this. For I am well aware that scarcely a single point is discussed in this volume on which facts cannot be adduced, often apparently leading to conclusions directly opposite to those at which I have arrived. A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question; and this cannot possibly be here done. I much regret that want of space prevents my having the satisfaction of acknowledging the generous assistance which I have received from very many naturalists, some of them personally unknown to me. I cannot, however, {3} let this opportunity pass without expressing my deep obligations to Dr. Hooker, who for the last fifteen years has aided me in every possible way by his large stores of knowledge and his excellent judgment. In considering the Origin of Species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that each species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which most justly excites our admiration. Naturalists continually refer to external conditions, such as climate, food, &c., as the only possible cause of variation. In one very limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the misseltoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself. The author of the 'Vestiges of Creation' would, I presume, say that, after a certain unknown number of {4} generations, some bird had given birth to a woodpecker, and some plant to the missletoe, and that these had been produced perfect as we now see them; but this assumption seems to me to be no explanation, for it leaves the case of the coadaptations of organic beings to each other and to their physical conditions of life, untouched and unexplained. It is, therefore, of the highest importance to gain a clear insight into the means of modification and coadaptation. At the commencement of my observations it seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this obscure problem. Nor have I been disappointed; in this and in all other perplexing cases I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the best and safest clue. I may venture to express my conviction of the high value of such studies, although they have been very commonly neglected by naturalists. From these considerations, I shall devote the first chapter of this Abstract to Variation under Domestication. We shall thus see that a large amount of hereditary modification is at least possible; and, what is equally or more important, we shall see how great is the power of man in accumulating by his Selection successive slight variations. I will then pass on to the variability of species in a state of nature; but I shall, unfortunately, be compelled to treat this subject far too briefly, as it can be treated properly only by giving long catalogues of facts. We shall, however, be enabled to discuss what circumstances are most favourable to variation. In the next chapter the Struggle for Existence amongst all organic beings throughout the world, which inevitably follows from the high geometrical ratio of their {5} increase, will be treated of. This is the doctrine of Malthus, applied to the whole animal and vegetable kingdoms. As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be _naturally selected_. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form. This fundamental subject of Natural Selection will be treated at some length in the fourth chapter; and we shall then see how Natural Selection almost inevitably causes much Extinction of the less improved forms of life, and leads to what I have called Divergence of Character. In the next chapter I shall discuss the complex and little known laws of variation and of correlation of growth. In the four succeeding chapters, the most apparent and gravest difficulties on the theory will be given: namely, first, the difficulties of transitions, or in understanding how a simple being or a simple organ can be changed and perfected into a highly developed being or elaborately constructed organ; secondly, the subject of Instinct, or the mental powers of animals; thirdly, Hybridism, or the infertility of species and the fertility of varieties when intercrossed; and fourthly, the imperfection of the Geological Record. In the next chapter I shall consider the geological succession of organic beings throughout time; in the eleventh and twelfth, their geographical distribution throughout space; in the thirteenth, their classification or mutual affinities, both when mature and in an embryonic condition. In the last chapter I shall give a {6} brief recapitulation of the whole work, and a few concluding remarks. No one ought to feel surprise at much remaining as yet unexplained in regard to the origin of species and varieties, if he makes due allowance for our profound ignorance in regard to the mutual relations of all the beings which live around us. Who can explain why one species ranges widely and is very numerous, and why another allied species has a narrow range and is rare? Yet these relations are of the highest importance, for they determine the present welfare, and, as I believe, the future success and modification of every inhabitant of this world. Still less do we know of the mutual relations of the innumerable inhabitants of the world during the many past geological epochs in its history. Although much remains obscure, and will long remain obscure, I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists entertain, and which I formerly entertained--namely, that each species has been independently created--is erroneous. I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am convinced that Natural Selection has been the main but not exclusive means of modification. * * * * * {7} CHAPTER I. VARIATION UNDER DOMESTICATION. Causes of Variability--Effects of Habit--Correlation of Growth--Inheritance--Character of Domestic Varieties--Difficulty of distinguishing between Varieties and Species--Origin of Domestic Varieties from one or more Species--Domestic Pigeons, their Differences and Origin--Principle of Selection anciently followed, its Effects--Methodical and Unconscious Selection--Unknown Origin of our Domestic Productions--Circumstances favourable to Man's power of Selection. When we look to the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us, is, that they generally differ more from each other than do the individuals of any one species or variety in a state of nature. When we reflect on the vast diversity of the plants and animals which have been cultivated, and which have varied during all ages under the most different climates and treatment, I think we are driven to conclude that this great variability is simply due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent-species have been exposed under nature. There is also, I think, some probability in the view propounded by Andrew Knight, that this variability may be partly connected with excess of food. It seems pretty clear that organic beings must be exposed during several generations to the new conditions of life to cause any appreciable amount of variation; and that when the organisation has once begun to vary, it generally continues to vary for many generations. {8} No case is on record of a variable being ceasing to be variable under cultivation. Our oldest cultivated plants, such as wheat, still often yield new varieties: our oldest domesticated animals are still capable of rapid improvement or modification. It has been disputed at what period of life the causes of variability, whatever they may be, generally act; whether during the early or late period of development of the embryo, or at the instant of conception. Geoffroy St. Hilaire's experiments show that unnatural treatment of the embryo causes monstrosities; and monstrosities cannot be separated by any clear line of distinction from mere variations. But I am strongly inclined to suspect that the most frequent cause of variability may be attributed to the male and female reproductive elements having been affected prior to the act of conception. Several reasons make me believe in this; but the chief one is the remarkable effect which confinement or cultivation has on the function of the reproductive system; this system appearing to be far more susceptible than any other part of the organisation, to the action of any change in the conditions of life. Nothing is more easy than to tame an animal, and few things more difficult than to get it to breed freely under confinement, even in the many cases when the male and female unite. How many animals there are which will not breed, though living long under not very close confinement in their native country! This is generally attributed to vitiated instincts; but how many cultivated plants display the utmost vigour, and yet rarely or never seed! In some few such cases it has been discovered that very trifling changes, such as a little more or less water at some particular period of growth, will determine whether or not the plant sets a seed. I cannot here enter on the copious details which I have collected on {9} this curious subject; but to show how singular the laws are which determine the reproduction of animals under confinement, I may just mention that carnivorous animals, even from the tropics, breed in this country pretty freely under confinement, with the exception of the plantigrades or bear family; whereas carnivorous birds, with the rarest exceptions, hardly ever lay fertile eggs. Many exotic plants have pollen utterly worthless, in the same exact condition as in the most sterile hybrids. When, on the one hand, we see domesticated animals and plants, though often weak and sickly, yet breeding quite freely under confinement; and when, on the other hand, we see individuals, though taken young from a state of nature, perfectly tamed, long-lived, and healthy (of which I could give numerous instances), yet having their reproductive system so seriously affected by unperceived causes as to fail in acting, we need not be surprised at this system, when it does act under confinement, acting not quite regularly, and producing offspring not perfectly like their parents. Sterility has been said to be the bane of horticulture; but on this view we owe variability to the same cause which produces sterility; and variability is the source of all the choicest productions of the garden. I may add, that as some organisms will breed freely under the most unnatural conditions (for instance, the rabbit and ferret kept in hutches), showing that their reproductive system has not been thus affected; so will some animals and plants withstand domestication or cultivation, and vary very slightly--perhaps hardly more than in a state of nature. A long list could easily be given of "sporting plants;" by this term gardeners mean a single bud or offset, which suddenly assumes a new and sometimes very different character from that of the rest of the plant. {10} Such buds can be propagated by grafting, &c., and sometimes by seed. These "sports" are extremely rare under nature, but far from rare under cultivation; and in this case we see that the treatment of the parent has affected a bud or offset, and not the ovules or pollen. But it is the opinion of most physiologists that there is no essential difference between a bud and an ovule in their earliest stages of formation; so that, in fact, "sports" support my view, that variability may be largely attributed to the ovules or pollen, or to both, having been affected by the treatment of the parent prior to the act of conception. These cases anyhow show that variation is not necessarily connected, as some authors have supposed, with the act of generation. Seedlings from the same fruit, and the young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Müller has remarked, have apparently been exposed to exactly the same conditions of life; and this shows how unimportant the direct effects of the conditions of life are in comparison with the laws of reproduction, of growth, and of inheritance; for had the action of the conditions been direct, if any of the young had varied, all would probably have varied in the same manner. To judge how much, in the case of any variation, we should attribute to the direct action of heat, moisture, light, food, &c., is most difficult: my impression is, that with animals such agencies have produced very little direct effect, though apparently more in the case of plants. Under this point of view, Mr. Buckman's recent experiments on plants are extremely valuable. When all or nearly all the individuals exposed to certain conditions are affected in the same way, the change at first appears to be directly due to such conditions; but in some cases it can be shown that quite opposite conditions produce {11} similar changes of structure. Nevertheless some slight amount of change may, I think, be attributed to the direct action of the conditions of life--as, in some cases, increased size from amount of food, colour from particular kinds of food or from light, and perhaps the thickness of fur from climate. Habit also has a decided influence, as in the period of flowering with plants when transported from one climate to another. In animals it has a more marked effect; for instance, I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more, in proportion to the whole skeleton, than do the same bones in the wild-duck; and I presume that this change may be safely attributed to the domestic duck flying much less, and walking more, than its wild parent. The great and inherited development of the udders in cows and goats in countries where they are habitually milked, in comparison with the state of these organs in other countries, is another instance of the effect of use. Not a single domestic animal can be named which has not in some country drooping ears; and the view suggested by some authors, that the drooping is due to the disuse of the muscles of the ear, from the animals not being much alarmed by danger, seems probable. There are many laws regulating variation, some few of which can be dimly seen, and will be hereafter briefly mentioned. I will here only allude to what may be called correlation of growth. Any change in the embryo or larva will almost certainly entail changes in the mature animal. In monstrosities, the correlations between quite distinct parts are very curious; and many instances are given in Isidore Geoffroy St. Hilaire's great work on this subject. Breeders believe that long limbs are almost always accompanied by an elongated head. Some instances of correlation are quite whimsical: thus {12} cats with blue eyes are invariably deaf; colour and constitutional peculiarities go together, of which many remarkable cases could be given amongst animals and plants. From the facts collected by Heusinger, it appears that white sheep and pigs are differently affected from coloured individuals by certain vegetable poisons. Hairless dogs have imperfect teeth: long-haired and coarse-haired animals are apt to have, as is asserted, long or many horns; pigeons with feathered feet have skin between their outer toes; pigeons with short beaks have small feet, and those with long beaks large feet. Hence, if man goes on selecting, and thus augmenting, any peculiarity, he will almost certainly unconsciously modify other parts of the structure, owing to the mysterious laws of the correlation of growth. The result of the various, quite unknown, or dimly seen laws of variation is infinitely complex and diversified. It is well worth while carefully to study the several treatises published on some of our old cultivated plants, as on the hyacinth, potato, even the dahlia, &c.; and it is really surprising to note the endless points in structure and constitution in which the varieties and sub-varieties differ slightly from each other. The whole organisation seems to have become plastic, and tends to depart in some small degree from that of the parental type. Any variation which is not inherited is unimportant for us. But the number and diversity of inheritable deviations of structure, both those of slight and those of considerable physiological importance, is endless. Dr. Prosper Lucas's treatise, in two large volumes, is the fullest and the best on this subject. No breeder doubts how strong is the tendency to inheritance: like produces like is his fundamental belief: doubts have been thrown on this principle by theoretical writers alone. When any deviation of structure often appears, and we see it in the {13} father and child, we cannot tell whether it may not be due to the same cause having acted on both; but when amongst individuals, apparently exposed to the same conditions, any very rare deviation, due to some extraordinary combination of circumstances, appears in the parent--say, once amongst several million individuals--and it reappears in the child, the mere doctrine of chances almost compels us to attribute its reappearance to inheritance. Every one must have heard of cases of albinism, prickly skin, hairy bodies, &c., appearing in several members of the same family. If strange and rare deviations of structure are truly inherited, less strange and commoner deviations may be freely admitted to be inheritable. Perhaps the correct way of viewing the whole subject, would be, to look at the inheritance of every character whatever as the rule, and non-inheritance as the anomaly. The laws governing inheritance are quite unknown; no one can say why a peculiarity in different individuals of the same species, or in individuals of different species, is sometimes inherited and sometimes not so; why the child often reverts in certain characters to its grandfather or grandmother or other more remote ancestor; why a peculiarity is often transmitted from one sex to both sexes, or to one sex alone, more commonly but not exclusively to the like sex. It is a fact of some little importance to us, that peculiarities appearing in the males of our domestic breeds are often transmitted either exclusively, or in a much greater degree, to males alone. A much more important rule, which I think may be trusted, is that, at whatever period of life a peculiarity first appears, it tends to appear in the offspring at a corresponding age, though sometimes earlier. In many cases this could not be otherwise: thus the inherited peculiarities in the horns of cattle could appear only in {14} the offspring when nearly mature; peculiarities in the silkworm are known to appear at the corresponding caterpillar or cocoon stage. But hereditary diseases and some other facts make me believe that the rule has a wider extension, and that when there is no apparent reason why a peculiarity should appear at any particular age, yet that it does tend to appear in the offspring at the same period at which it first appeared in the parent. I believe this rule to be of the highest importance in explaining the laws of embryology. These remarks are of course confined to the first _appearance_ of the peculiarity, and not to its primary cause, which may have acted on the ovules or male element; in nearly the same manner as in the crossed offspring from a short-horned cow by a long-horned bull, the greater length of horn, though appearing late in life, is clearly due to the male element. Having alluded to the subject of reversion, I may here refer to a statement often made by naturalists--namely, that our domestic varieties, when run wild, gradually but certainly revert in character to their aboriginal stocks. Hence it has been argued that no deductions can be drawn from domestic races to species in a state of nature. I have in vain endeavoured to discover on what decisive facts the above statement has so often and so boldly been made. There would be great difficulty in proving its truth: we may safely conclude that very many of the most strongly-marked domestic varieties could not possibly live in a wild state. In many cases we do not know what the aboriginal stock was, and so could not tell whether or not nearly perfect reversion had ensued. It would be quite necessary, in order to prevent the effects of intercrossing, that only a single variety should be turned loose in its new home. Nevertheless, as our varieties certainly do occasionally {15} revert in some of their characters to ancestral forms, it seems to me not improbable, that if we could succeed in naturalising, or were to cultivate, during many generations, the several races, for instance, of the cabbage, in very poor soil (in which case, however, some effect would have to be attributed to the direct action of the poor soil), that they would to a large extent, or even wholly, revert to the wild aboriginal stock. Whether or not the experiment would succeed, is not of great importance for our line of argument; for by the experiment itself the conditions of life are changed. If it could be shown that our domestic varieties manifested a strong tendency to reversion,--that is, to lose their acquired characters, whilst kept under the same conditions, and whilst kept in a considerable body, so that free intercrossing might check, by blending together, any slight deviations in their structure, in such case, I grant that we could deduce nothing from domestic varieties in regard to species. But there is not a shadow of evidence in favour of this view: to assert that we could not breed our cart and race-horses, long and short-horned cattle, and poultry of various breeds, and esculent vegetables, for an almost infinite number of generations, would be opposed to all experience. I may add, that when under nature the conditions of life do change, variations and reversions of character probably do occur; but natural selection, as will hereafter be explained, will determine how far the new characters thus arising shall be preserved. When we look to the hereditary varieties or races of our domestic animals and plants, and compare them with closely allied species, we generally perceive in each domestic race, as already remarked, less uniformity of character than in true species. Domestic races of the same species, also, often have a somewhat monstrous character; by which I mean, that, although differing {16} from each other, and from other species of the same genus, in several trifling respects, they often differ in an extreme degree in some one part, both when compared one with another, and more especially when compared with all the species in nature to which they are nearest allied. With these exceptions (and with that of the perfect fertility of varieties when crossed,--a subject hereafter to be discussed), domestic races of the same species differ from each other in the same manner as, only in most cases in a lesser degree than, do closely-allied species of the same genus in a state of nature. I think this must be admitted, when we find that there are hardly any domestic races, either amongst animals or plants, which have not been ranked by competent judges as mere varieties, and by other competent judges as the descendants of aboriginally distinct species. If any marked distinction existed between domestic races and species, this source of doubt could not so perpetually recur. It has often been stated that domestic races do not differ from each other in characters of generic value. I think it could be shown that this statement is hardly correct; but naturalists differ widely in determining what characters are of generic value; all such valuations being at present empirical. Moreover, on the view of the origin of genera which I shall presently give, we have no right to expect often to meet with generic differences in our domesticated productions. When we attempt to estimate the amount of structural difference between the domestic races of the same species, we are soon involved in doubt, from not knowing whether they have descended from one or several parent-species. This point, if it could be cleared up, would be interesting; if, for instance, it could be shown that the greyhound, bloodhound, terrier, spaniel, and bull-dog, which we all know propagate their kind so truly, were the {17} offspring of any single species, then such facts would have great weight in making us doubt about the immutability of the many very closely allied natural species--for instance, of the many foxes--inhabiting different quarters of the world. I do not believe, as we shall presently see, that the whole amount of difference between the several breeds of the dog has been produced under domestication; I believe that some small part of the difference is due to their being descended from distinct species. In the case of some other domesticated species, there is presumptive, or even strong evidence, that all the breeds have descended from a single wild stock. It has often been assumed that man has chosen for domestication animals and plants having an extraordinary inherent tendency to vary, and likewise to withstand diverse climates. I do not dispute that these capacities have added largely to the value of most of our domesticated productions; but how could a savage possibly know, when he first tamed an animal, whether it would vary in succeeding generations, and whether it would endure other climates? Has the little variability of the ass or guinea-fowl, or the small power of endurance of warmth by the reindeer, or of cold by the common camel, prevented their domestication? I cannot doubt that if other animals and plants, equal in number to our domesticated productions, and belonging to equally diverse classes and countries, were taken from a state of nature, and could be made to breed for an equal number of generations under domestication, they would vary on an average as largely as the parent species of our existing domesticated productions have varied. In the case of most of our anciently domesticated animals and plants, I do not think it is possible to come to any definite conclusion, whether they have descended from one or several wild species. The argument mainly relied on by those who believe in the multiple origin {18} of our domestic animals is, that we find in the most ancient records, more especially on the monuments of Egypt, much diversity in the breeds; and that some of the breeds closely resemble, perhaps are identical with, those still existing. Even if this latter fact were found more strictly and generally true than seems to me to be the case, what does it show, but that some of our breeds originated there, four or five thousand years ago? But Mr. Horner's researches have rendered it in some degree probable that man sufficiently civilized to have manufactured pottery existed in the valley of the Nile thirteen or fourteen thousand years ago; and who will pretend to say how long before these ancient periods, savages, like those of Tierra del Fuego or Australia, who possess a semi-domestic dog, may not have existed in Egypt? The whole subject must, I think, remain vague; nevertheless, I may, without here entering on any details, state that, from geographical and other considerations, I think it highly probable that our domestic dogs have descended from several wild species. Knowing, as we do, that savages are very fond of taming animals, it seems to me unlikely, in the case of the dog-genus, which is distributed in a wild state throughout the world, that since man first appeared one single species alone should have been domesticated. In regard to sheep and goats I can form no opinion. I should think, from facts communicated to me by Mr. Blyth, on the habits, voice, and constitution, &c., of the humped Indian cattle, that these had descended from a different aboriginal stock from our European cattle; and several competent judges believe that these latter have had more than one wild parent. With respect to horses, from reasons which I cannot give here, I am doubtfully inclined to believe, in opposition to several authors, that all the races have descended from one {19} wild stock. Mr. Blyth, whose opinion, from his large and varied stores of knowledge, I should value more than that of almost any one, thinks that all the breeds of poultry have proceeded from the common wild Indian fowl (Gallus bankiva). In regard to ducks and rabbits, the breeds of which differ considerably from each other in structure, I do not doubt that they have all descended from the common wild duck and rabbit. The doctrine of the origin of our several domestic races from several aboriginal stocks, has been carried to an absurd extreme by some authors. They believe that every race which breeds true, let the distinctive characters be ever so slight, has had its wild prototype. At this rate there must have existed at least a score of species of wild cattle, as many sheep, and several goats in Europe alone, and several even within Great Britain. One author believes that there formerly existed in Great Britain eleven wild species of sheep peculiar to it! When we bear in mind that Britain has now hardly one peculiar mammal, and France but few distinct from those of Germany and conversely, and so with Hungary, Spain, &c., but that each of these kingdoms possesses several peculiar breeds of cattle, sheep, &c., we must admit that many domestic breeds have originated in Europe; for whence could they have been derived, as these several countries do not possess a number of peculiar species as distinct parent-stocks? So it is in India. Even in the case of the domestic dogs of the whole world, which I fully admit have probably descended from several wild species, I cannot doubt that there has been an immense amount of inherited variation. Who can believe that animals closely resembling the Italian greyhound, the bloodhound, the bull-dog, or Blenheim spaniel, &c.--so unlike all wild Canidæ--ever existed freely in a state of nature? It has often been loosely said that all our races of dogs have {20} been produced by the crossing of a few aboriginal species; but by crossing we can only get forms in some degree intermediate between their parents; and if we account for our several domestic races by this process, we must admit the former existence of the most extreme forms, as the Italian greyhound, bloodhound, bull-dog, &c., in the wild state. Moreover, the possibility of making distinct races by crossing has been greatly exaggerated. There can be no doubt that a race may be modified by occasional crosses, if aided by the careful selection of those individual mongrels, which present any desired character; but that a race could be obtained nearly intermediate between two extremely different races or species, I can hardly believe. Sir J. Sebright expressly experimentised for this object, and failed. The offspring from the first cross between two pure breeds is tolerably and sometimes (as I have found with pigeons) extremely uniform, and everything seems simple enough; but when these mongrels are crossed one with another for several generations, hardly two of them will be alike, and then the extreme difficulty, or rather utter hopelessness, of the task becomes apparent. Certainly, a breed intermediate between _two very distinct_ breeds could not be got without extreme care and long-continued selection; nor can I find a single case on record of a permanent race having been thus formed. _On the Breeds of the Domestic Pigeon._--Believing that it is always best to study some special group, I have, after deliberation, taken up domestic pigeons. I have kept every breed which I could purchase or obtain, and have been most kindly favoured with skins from several quarters of the world, more especially by the Hon. W. Elliot from India, and by the Hon. C. Murray from Persia. Many treatises in different languages have been published on pigeons, and some of them are very important, as being of {21} considerable antiquity. I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs. The diversity of the breeds is something astonishing. Compare the English carrier and the short-faced tumbler, and see the wonderful difference in their beaks, entailing corresponding differences in their skulls. The carrier, more especially the male bird, is also remarkable from the wonderful development of the carunculated skin about the head, and this is accompanied by greatly elongated eyelids, very large external orifices to the nostrils, and a wide gape of mouth. The short-faced tumbler has a beak in outline almost like that of a finch; and the common tumbler has the singular inherited habit of flying at a great height in a compact flock, and tumbling in the air head over heels. The runt is a bird of great size, with long, massive beak and large feet; some of the sub-breeds of runts have very long necks, others very long wings and tails, others singularly short tails. The barb is allied to the carrier, but, instead of a very long beak, has a very short and very broad one. The pouter has a much elongated body, wings, and legs; and its enormously developed crop, which it glories in inflating, may well excite astonishment and even laughter. The turbit has a very short and conical beak, with a line of reversed feathers down the breast; and it has the habit of continually expanding slightly the upper part of the oesophagus. The Jacobin has the feathers so much reversed along the back of the neck that they form a hood, and it has, proportionally to its size, much elongated wing and tail feathers. The trumpeter and laugher, as their names express, utter a very different coo from the other breeds. The fantail has thirty or even forty tail feathers, instead of twelve or fourteen, the normal number in all members of the great pigeon family; and these feathers are kept expanded, and are {22} carried so erect that in good birds the head and tail touch; the oil-gland is quite aborted. Several other less distinct breeds might be specified. In the skeletons of the several breeds, the development of the bones of the face in length and breadth and curvature differs enormously. The shape, as well as the breadth and length of the ramus of the lower jaw, varies in a highly remarkable manner. The number of the caudal and sacral vertebræ vary; as does the number of the ribs, together with their relative breadth and the presence of processes. The size and shape of the apertures in the sternum are highly variable; so is the degree of divergence and relative size of the two arms of the furcula. The proportional width of the gape of mouth, the proportional length of the eyelids, of the orifice of the nostrils, of the tongue (not always in strict correlation with the length of beak), the size of the crop and of the upper part of the oesophagus; the development and abortion of the oil-gland; the number of the primary wing and caudal feathers; the relative length of wing and tail to each other and to the body; the relative length of leg and of the feet; the number of scutellæ on the toes, the development of skin between the toes, are all points of structure which are variable. The period at which the perfect plumage is acquired varies, as does the state of the down with which the nestling birds are clothed when hatched. The shape and size of the eggs vary. The manner of flight differs remarkably; as does in some breeds the voice and disposition. Lastly, in certain breeds, the males and females have come to differ to a slight degree from each other. Altogether at least a score of pigeons might be chosen, which if shown to an ornithologist, and he were told that they were wild birds, would certainly, I think, be ranked by him as well-defined species. Moreover, I do not believe that any ornithologist would place the {23} English carrier, the short-faced tumbler, the runt, the barb, pouter, and fantail in the same genus; more especially as in each of these breeds several truly-inherited sub-breeds, or species as he might have called them, could be shown him. Great as the differences are between the breeds of pigeons, I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock-pigeon (Columba livia), including under this term several geographical races or sub-species, which differ from each other in the most trifling respects. As several of the reasons which have led me to this belief are in some degree applicable in other cases, I will here briefly give them. If the several breeds are not varieties, and have not proceeded from the rock-pigeon, they must have descended from at least seven or eight aboriginal stocks; for it is impossible to make the present domestic breeds by the crossing of any lesser number: how, for instance, could a pouter be produced by crossing two breeds unless one of the parent-stocks possessed the characteristic enormous crop? The supposed aboriginal stocks must all have been rock-pigeons, that is, not breeding or willingly perching on trees. But besides C. livia, with its geographical sub-species, only two or three other species of rock-pigeons are known; and these have not any of the characters of the domestic breeds. Hence the supposed aboriginal stocks must either still exist in the countries where they were originally domesticated, and yet be unknown to ornithologists; and this, considering their size, habits, and remarkable characters, seems very improbable; or they must have become extinct in the wild state. But birds breeding on precipices, and good fliers, are unlikely to be exterminated; and the common rock-pigeon, which has the same habits with the domestic breeds, has not been exterminated {24} even on several of the smaller British islets, or on the shores of the Mediterranean. Hence the supposed extermination of so many species having similar habits with the rock-pigeon seems to me a very rash assumption. Moreover, the several above-named domesticated breeds have been transported to all parts of the world, and, therefore, some of them must have been carried back again into their native country; but not one has ever become wild or feral, though the dovecot-pigeon, which is the rock-pigeon in a very slightly altered state, has become feral in several places. Again, all recent experience shows that it is most difficult to get any wild animal to breed freely under domestication; yet on the hypothesis of the multiple origin of our pigeons, it must be assumed that at least seven or eight species were so thoroughly domesticated in ancient times by half-civilized man, as to be quite prolific under confinement. An argument, as it seems to me, of great weight, and applicable in several other cases, is, that the above-specified breeds, though agreeing generally in constitution, habits, voice, colouring, and in most parts of their structure, with the wild rock-pigeon, yet are certainly highly abnormal in other parts of their structure; we may look in vain throughout the whole great family of Columbidæ for a beak like that of the English carrier, or that of the short-faced tumbler, or barb; for reversed feathers like those of the Jacobin; for a crop like that of the pouter; for tail-feathers like those of the fantail. Hence it must be assumed not only that half-civilized man succeeded in thoroughly domesticating several species, but that he intentionally or by chance picked out extraordinarily abnormal species; and further, that these very species have since all become extinct or unknown. So many strange contingencies seem to me improbable in the highest degree. {25} Some facts in regard to the colouring of pigeons well deserve consideration. The rock-pigeon is of a slaty-blue, and has a white rump (the Indian subspecies, C. intermedia of Strickland, having it bluish); the tail has a terminal dark bar, with the bases of the outer feathers externally edged with white; the wings have two black bars; some semi-domestic breeds and some apparently truly wild breeds have, besides the two black bars, the wings chequered with black. These several marks do not occur together in any other species of the whole family. Now, in every one of the domestic breeds, taking thoroughly well-bred birds, all the above marks, even to the white edging of the outer tail-feathers, sometimes concur perfectly developed. Moreover, when two birds belonging to two distinct breeds are crossed, neither of which is blue or has any of the above-specified marks, the mongrel offspring are very apt suddenly to acquire these characters; for instance, I crossed some uniformly white fantails with some uniformly black barbs, and they produced mottled brown and black birds; these I again crossed together, and one grandchild of the pure white fantail and pure black barb was of as beautiful a blue colour, with the white rump, double black wing-bar, and barred and white-edged tail-feathers, as any wild rock-pigeon! We can understand these facts, on the well-known principle of reversion to ancestral characters, if all the domestic breeds have descended from the rock-pigeon. But if we deny this, we must make one of the two following highly improbable suppositions. Either, firstly, that all the several imagined aboriginal stocks were coloured and marked like the rock-pigeon, although no other existing species is thus coloured and marked, so that in each separate breed there might be a tendency to revert to the very same colours and markings. Or, secondly, {26} that each breed, even the purest, has within a dozen or, at most, within a score of generations, been crossed by the rock-pigeon: I say within a dozen or twenty generations, for we know of no fact countenancing the belief that the child ever reverts to some one ancestor, removed by a greater number of generations. In a breed which has been crossed only once with some distinct breed, the tendency to reversion to any character derived from such cross will naturally become less and less, as in each succeeding generation there will be less of the foreign blood; but when there has been no cross with a distinct breed, and there is a tendency in both parents to revert to a character, which has been lost during some former generation, this tendency, for all that we can see to the contrary, may be transmitted undiminished for an indefinite number of generations. These two distinct cases are often confounded in treatises on inheritance. Lastly, the hybrids or mongrels from between all the domestic breeds of pigeons are perfectly fertile. I can state this from my own observations, purposely made, on the most distinct breeds. Now, it is difficult, perhaps impossible, to bring forward one case of the hybrid offspring of two animals _clearly distinct_ being themselves perfectly fertile. Some authors believe that long-continued domestication eliminates this strong tendency to sterility: from the history of the dog I think there is some probability in this hypothesis, if applied to species closely related together, though it is unsupported by a single experiment. But to extend the hypothesis so far as to suppose that species, aboriginally as distinct as carriers, tumblers, pouters, and fantails now are, should yield offspring perfectly fertile, _inter se_, seems to me rash in the extreme. From these several reasons, namely, the improbability of man having formerly got seven or eight supposed {27} species of pigeons to breed freely under domestication; these supposed species being quite unknown in a wild state, and their becoming nowhere feral; these species having very abnormal characters in certain respects, as compared with all other Columbidæ, though so like in most other respects to the rock-pigeon; the blue colour and various marks occasionally appearing in all the breeds, both when kept pure and when crossed; the mongrel offspring being perfectly fertile;--from these several reasons, taken together, I can feel no doubt that all our domestic breeds have descended from the Columba livia with its geographical sub-species. In favour of this view, I may add, firstly, that C. livia, or the rock-pigeon, has been found capable of domestication in Europe and in India; and that it agrees in habits and in a great number of points of structure with all the domestic breeds. Secondly, although an English carrier or short-faced tumbler differs immensely in certain characters from the rock-pigeon, yet by comparing the several sub-breeds of these varieties, more especially those brought from distant countries, we can make an almost perfect series between the extremes of structure. Thirdly, those characters which are mainly distinctive of each breed, for instance the wattle and length of beak of the carrier, the shortness of that of the tumbler, and the number of tail-feathers in the fantail, are in each breed eminently variable; and the explanation of this fact will be obvious when we come to treat of selection. Fourthly, pigeons have been watched, and tended with the utmost care, and loved by many people. They have been domesticated for thousands of years in several quarters of the world; the earliest known record of pigeons is in the fifth Ægyptian dynasty, about 3000 B.C., as was pointed out to me by Professor Lepsius; but Mr. Birch informs me that pigeons are given in a bill {28} of fare in the previous dynasty. In the time of the Romans, as we hear from Pliny, immense prices were given for pigeons; "nay, they are come to this pass, that they can reckon up their pedigree and race." Pigeons were much valued by Akber Khan in India, about the year 1600; never less than 20,000 pigeons were taken with the court. "The monarchs of Iran and Turan sent him some very rare birds;" and, continues the courtly historian, "His Majesty by crossing the breeds, which method was never practised before, has improved them astonishingly." About this same period the Dutch were as eager about pigeons as were the old Romans. The paramount importance of these considerations in explaining the immense amount of variation which pigeons have undergone, will be obvious when we treat of Selection. We shall then, also, see how it is that the breeds so often have a somewhat monstrous character. It is also a most favourable circumstance for the production of distinct breeds, that male and female pigeons can be easily mated for life; and thus different breeds can be kept together in the same aviary. I have discussed the probable origin of domestic pigeons at some, yet quite insufficient, length; because when I first kept pigeons and watched the several kinds, knowing well how true they bred, I felt fully as much difficulty in believing that they could have descended from a common parent, as any naturalist could in coming to a similar conclusion in regard to the many species of finches, or other large groups of birds, in nature. One circumstance has struck me much; namely, that all the breeders of the various domestic animals and the cultivators of plants, with whom I have ever conversed, or whose treatises I have read, are firmly convinced that the several breeds to which each has attended, are descended from so many aboriginally distinct species. {29} Ask, as I have asked, a celebrated raiser of Hereford cattle, whether his cattle might not have descended from long-horns, and he will laugh you to scorn. I have never met a pigeon, or poultry, or duck, or rabbit fancier, who was not fully convinced that each main breed was descended from a distinct species. Van Mons, in his treatise on pears and apples, shows how utterly he disbelieves that the several sorts, for instance a Ribston-pippin or Codlin-apple, could ever have proceeded from the seeds of the same tree. Innumerable other examples could be given. The explanation, I think, is simple: from long-continued study they are strongly impressed with the differences between the several races; and though they well know that each race varies slightly, for they win their prizes by selecting such slight differences, yet they ignore all general arguments, and refuse to sum up in their minds slight differences accumulated during many successive generations. May not those naturalists who, knowing far less of the laws of inheritance than does the breeder, and knowing no more than he does of the intermediate links in the long lines of descent, yet admit that many of our domestic races have descended from the same parents--may they not learn a lesson of caution, when they deride the idea of species in a state of nature being lineal descendants of other species? _Selection._--Let us now briefly consider the steps by which domestic races have been produced, either from one or from several allied species. Some little effect may, perhaps, be attributed to the direct action of the external conditions of life, and some little to habit; but he would be a bold man who would account by such agencies for the differences of a dray and race horse, a greyhound and bloodhound, a carrier and tumbler pigeon. One of the most remarkable features in our domesticated races {30} is that we see in them adaptation, not indeed to the animal's or plant's own good, but to man's use or fancy. Some variations useful to him have probably arisen suddenly, or by one step; many botanists, for instance, believe that the fuller's teazle, with its hooks, which cannot be rivalled by any mechanical contrivance, is only a variety of the wild Dipsacus; and this amount of change may have suddenly arisen in a seedling. So it has probably been with the turnspit dog; and this is known to have been the case with the ancon sheep. But when we compare the dray-horse and race-horse, the dromedary and camel, the various breeds of sheep fitted either for cultivated land or mountain pasture, with the wool of one breed good for one purpose, and that of another breed for another purpose; when we compare the many breeds of dogs, each good for man in very different ways; when we compare the game-cock, so pertinacious in battle, with other breeds so little quarrelsome, with "everlasting layers" which never desire to sit, and with the bantam so small and elegant; when we compare the host of agricultural, culinary, orchard, and flower-garden races of plants, most useful to man at different seasons and for different purposes, or so beautiful in his eyes, we must, I think, look further than to mere variability. We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed, in several cases, we know that this has not been their history. The key is man's power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to make for himself useful breeds. The great power of this principle of selection is not hypothetical. It is certain that several of our eminent breeders have, even within a single lifetime, modified to {31} a large extent some breeds of cattle and sheep. In order fully to realise what they have done, it is almost necessary to read several of the many treatises devoted to this subject, and to inspect the animals. Breeders habitually speak of an animal's organisation as something quite plastic, which they can model almost as they please. If I had space I could quote numerous passages to this effect from highly competent authorities. Youatt, who was probably better acquainted with the works of agriculturists than almost any other individual, and who was himself a very good judge of an animal, speaks of the principle of selection as "that which enables the agriculturist, not only to modify the character of his flock, but to change it altogether. It is the magician's wand, by means of which he may summon into life whatever form and mould he pleases." Lord Somerville, speaking of what breeders have done for sheep, says:--"It would seem as if they had chalked out upon a wall a form perfect in itself, and then had given it existence." That most skilful breeder, Sir John Sebright, used to say, with respect to pigeons, that "he would produce any given feather in three years, but it would take him six years to obtain head and beak." In Saxony the importance of the principle of selection in regard to merino sheep is so fully recognised, that men follow it as a trade: the sheep are placed on a table and are studied, like a picture by a connoisseur; this is done three times at intervals of months, and the sheep are each time marked and classed, so that the very best may ultimately be selected for breeding. What English breeders have actually effected is proved by the enormous prices given for animals with a good pedigree; and these have now been exported to almost every quarter of the world. The improvement is by no means generally due to crossing different breeds; {32} all the best breeders are strongly opposed to this practice, except sometimes amongst closely allied sub-breeds. And when a cross has been made, the closest selection is far more indispensable even than in ordinary cases. If selection consisted merely in separating some very distinct variety, and breeding from it, the principle would be so obvious as hardly to be worth notice; but its importance consists in the great effect produced by the accumulation in one direction, during successive generations, of differences absolutely inappreciable by an uneducated eye--differences which I for one have vainly attempted to appreciate. Not one man in a thousand has accuracy of eye and judgment sufficient to become an eminent breeder. If gifted with these qualities, and he studies his subject for years, and devotes his lifetime to it with indomitable perseverance, he will succeed, and may make great improvements; if he wants any of these qualities, he will assuredly fail. Few would readily believe in the natural capacity and years of practice requisite to become even a skilful pigeon-fancier. The same principles are followed by horticulturists; but the variations are here often more abrupt. No one supposes that our choicest productions have been produced by a single variation from the aboriginal stock. We have proofs that this is not so in some cases, in which exact records have been kept; thus, to give a very trifling instance, the steadily-increasing size of the common gooseberry may be quoted. We see an astonishing improvement in many florists' flowers, when the flowers of the present day are compared with drawings made only twenty or thirty years ago. When a race of plants is once pretty well established, the seed-raisers do not pick out the best plants, but merely go over their seed-beds, and pull up the "rogues," as they call the plants that deviate from the proper standard. With animals this {33} kind of selection is, in fact, also followed; for hardly any one is so careless as to allow his worst animals to breed. In regard to plants, there is another means of observing the accumulated effects of selection--namely, by comparing the diversity of flowers in the different varieties of the same species in the flower-garden; the diversity of leaves, pods, or tubers, or whatever part is valued, in the kitchen-garden, in comparison with the flowers of the same varieties; and the diversity of fruit of the same species in the orchard, in comparison with the leaves and flowers of the same set of varieties. See how different the leaves of the cabbage are, and how extremely alike the flowers; how unlike the flowers of the heartsease are, and how alike the leaves; how much the fruit of the different kinds of gooseberries differ in size, colour, shape, and hairiness, and yet the flowers present very slight differences. It is not that the varieties which differ largely in some one point do not differ at all in other points; this is hardly ever, perhaps never, the case. The laws of correlation of growth, the importance of which should never be overlooked, will ensure some differences; but, as a general rule, I cannot doubt that the continued selection of slight variations, either in the leaves, the flowers, or the fruit, will produce races differing from each other chiefly in these characters. It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three-quarters of a century; it has certainly been more attended to of late years, and many treatises have been published on the subject; and the result has been, in a corresponding degree, rapid and important. But it is very far from true that the principle is a modern discovery. I could give several references to the full acknowledgment of the importance of the principle in works of high antiquity. In rude and barbarous periods {34} of English history choice animals were often imported, and laws were passed to prevent their exportation: the destruction of horses under a certain size was ordered, and this may be compared to the "roguing" of plants by nurserymen. The principle of selection I find distinctly given in an ancient Chinese encyclopædia. Explicit rules are laid down by some of the Roman classical writers. From passages in Genesis, it is clear that the colour of domestic animals was at that early period attended to. Savages now sometimes cross their dogs with wild canine animals, to improve the breed, and they formerly did so, as is attested by passages in Pliny. The savages in South Africa match their draught cattle by colour, as do some of the Esquimaux their teams of dogs. Livingstone shows how much good domestic breeds are valued by the negroes of the interior of Africa who have not associated with Europeans. Some of these facts do not show actual selection, but they show that the breeding of domestic animals was carefully attended to in ancient times, and is now attended to by the lowest savages. It would, indeed, have been a strange fact, had attention not been paid to breeding, for the inheritance of good and bad qualities is so obvious. At the present time, eminent breeders try by methodical selection, with a distinct object in view, to make a new strain or sub-breed, superior to anything existing in the country. But, for our purpose, a kind of Selection, which may be called Unconscious, and which results from every one trying to possess and breed from the best individual animals, is more important. Thus, a man who intends keeping pointers naturally tries to get as good dogs as he can, and afterwards breeds from his own best dogs, but he has no wish or expectation of permanently altering the breed. Nevertheless I cannot doubt that this process, continued during centuries, {35} would improve and modify any breed, in the same way as Bakewell, Collins, &c., by this very same process, only carried on more methodically, did greatly modify, even during their own lifetimes, the forms and qualities of their cattle. Slow and insensible changes of this kind could never be recognised unless actual measurements or careful drawings of the breeds in question had been made long ago, which might serve for comparison. In some cases, however, unchanged, or but little changed individuals of the same breed may be found in less civilised districts, where the breed has been less improved. There is reason to believe that King Charles's spaniel has been unconsciously modified to a large extent since the time of that monarch. Some highly competent authorities are convinced that the setter is directly derived from the spaniel, and has probably been slowly altered from it. It is known that the English pointer has been greatly changed within the last century, and in this case the change has, it is believed, been chiefly effected by crosses with the fox-hound; but what concerns us is, that the change has been effected unconsciously and gradually, and yet so effectually, that, though the old Spanish pointer certainly came from Spain, Mr. Borrow has not seen, as I am informed by him, any native dog in Spain like our pointer. By a similar process of selection, and by careful training, the whole body of English racehorses have come to surpass in fleetness and size the parent Arab stock, so that the latter, by the regulations for the Goodwood Races, are favoured in the weights they carry. Lord Spencer and others have shown how the cattle of England have increased in weight and in early maturity, compared with the stock formerly kept in this country. By comparing the accounts given in old pigeon treatises of carriers and tumblers with these breeds as now existing in Britain, {36} India, and Persia, we can, I think, clearly trace the stages through which they have insensibly passed, and come to differ so greatly from the rock-pigeon. Youatt gives an excellent illustration of the effects of a course of selection, which may be considered as unconsciously followed, in so far that the breeders could never have expected or even have wished to have produced the result which ensued--namely, the production of two distinct strains. The two flocks of Leicester sheep kept by Mr. Buckley and Mr. Burgess, as Mr. Youatt remarks, "have been purely bred from the original stock of Mr. Bakewell for upwards of fifty years. There is not a suspicion existing in the mind of any one at all acquainted with the subject that the owner of either of them has deviated in any one instance from the pure blood of Mr. Bakewell's flock, and yet the difference between the sheep possessed by these two gentlemen is so great that they have the appearance of being quite different varieties." If there exist savages so barbarous as never to think of the inherited character of the offspring of their domestic animals, yet any one animal particularly useful to them, for any special purpose, would be carefully preserved during famines and other accidents, to which savages are so liable, and such choice animals would thus generally leave more offspring than the inferior ones; so that in this case there would be a kind of unconscious selection going on. We see the value set on animals even by the barbarians of Tierra del Fuego, by their killing and devouring their old women, in times of dearth, as of less value than their dogs. In plants the same gradual process of improvement, through the occasional preservation of the best individuals, whether or not sufficiently distinct to be ranked at their first appearance as distinct varieties, and whether {37} or not two or more species or races have become blended together by crossing, may plainly be recognised in the increased size and beauty which we now see in the varieties of the heartsease, rose, pelargonium, dahlia, and other plants, when compared with the older varieties or with their parent-stocks. No one would ever expect to get a first-rate heartsease or dahlia from the seed of a wild plant. No one would expect to raise a first-rate melting pear from the seed of the wild pear, though he might succeed from a poor seedling growing wild, if it had come from a garden-stock. The pear, though cultivated in classical times, appears, from Pliny's description, to have been a fruit of very inferior quality. I have seen great surprise expressed in horticultural works at the wonderful skill of gardeners, in having produced such splendid results from such poor materials; but the art, I cannot doubt, has been simple, and, as far as the final result is concerned, has been followed almost unconsciously. It has consisted in always cultivating the best known variety, sowing its seeds, and, when a slightly better variety has chanced to appear, selecting it, and so onwards. But the gardeners of the classical period, who cultivated the best pear they could procure, never thought what splendid fruit we should eat; though we owe our excellent fruit, in some small degree, to their having naturally chosen and preserved the best varieties they could anywhere find. A large amount of change in our cultivated plants, thus slowly and unconsciously accumulated, explains, as I believe, the well-known fact, that in a vast number of cases we cannot recognise, and therefore do not know, the wild parent-stocks of the plants which have been longest cultivated in our flower and kitchen gardens. If it has taken centuries or thousands of years to improve or modify most of our plants up to their present {38} standard of usefulness to man, we can understand how it is that neither Australia, the Cape of Good Hope, nor any other region inhabited by quite uncivilised man, has afforded us a single plant worth culture. It is not that these countries, so rich in species, do not by a strange chance possess the aboriginal stocks of any useful plants, but that the native plants have not been improved by continued selection up to a standard of perfection comparable with that given to the plants in countries anciently civilised. In regard to the domestic animals kept by uncivilised man, it should not be overlooked that they almost always have to struggle for their own food, at least during certain seasons. And in two countries very differently circumstanced, individuals of the same species, having slightly different constitutions or structure, would often succeed better in the one country than in the other; and thus by a process of "natural selection," as will hereafter be more fully explained, two sub-breeds might be formed. This, perhaps, partly explains what has been remarked by some authors, namely, that the varieties kept by savages have more of the character of species than the varieties kept in civilised countries. On the view here given of the all-important part which selection by man has played, it becomes at once obvious, how it is that our domestic races show adaptation in their structure or in their habits to man's wants or fancies. We can, I think, further understand the frequently abnormal character of our domestic races, and likewise their differences being so great in external characters and relatively so slight in internal parts or organs. Man can hardly select, or only with much difficulty, any deviation of structure excepting such as is externally visible; and indeed he rarely cares for what is internal. He can never act by selection, excepting on variations {39} which are first given to him in some slight degree by nature. No man would ever try to make a fantail, till he saw a pigeon with a tail developed in some slight degree in an unusual manner, or a pouter till he saw a pigeon with a crop of somewhat unusual size; and the more abnormal or unusual any character was when it first appeared, the more likely it would be to catch his attention. But to use such an expression as trying to make a fantail, is, I have no doubt, in most cases, utterly incorrect. The man who first selected a pigeon with a slightly larger tail, never dreamed what the descendants of that pigeon would become through long-continued, partly unconscious and partly methodical selection. Perhaps the parent bird of all fantails had only fourteen tail-feathers somewhat expanded, like the present Java fantail, or like individuals of other and distinct breeds, in which as many as seventeen tail-feathers have been counted. Perhaps the first pouter-pigeon did not inflate its crop much more than the turbit now does the upper part of its oesophagus,--a habit which is disregarded by all fanciers, as it is not one of the points of the breed. Nor let it be thought that some great deviation of structure would be necessary to catch the fancier's eye: he perceives extremely small differences, and it is in human nature to value any novelty, however slight, in one's own possession. Nor must the value which would formerly be set on any slight differences in the individuals of the same species, be judged of by the value which would now be set on them, after several breeds have once fairly been established. Many slight differences might, and indeed do now, arise amongst pigeons, which are rejected as faults or deviations from the standard of perfection of each breed. The common goose has not given rise to any marked varieties; hence the Thoulouse and the common breed, which differ only in colour, that {40} most fleeting of characters, have lately been exhibited as distinct at our poultry-shows. I think these views further explain what has sometimes been noticed--namely, that we know nothing about the origin or history of any of our domestic breeds. But, in fact, a breed, like a dialect of a language, can hardly be said to have had a definite origin. A man preserves and breeds from an individual with some slight deviation of structure, or takes more care than usual in matching his best animals and thus improves them, and the improved individuals slowly spread in the immediate neighbourhood. But as yet they will hardly have a distinct name, and from being only slightly valued, their history will be disregarded. When further improved by the same slow and gradual process, they will spread more widely, and will get recognised as something distinct and valuable, and will then probably first receive a provincial name. In semi-civilised countries, with little free communication, the spreading and knowledge of any new sub-breed will be a slow process. As soon as the points of value of the new sub-breed are once fully acknowledged, the principle, as I have called it, of unconscious selection will always tend,--perhaps more at one period than at another, as the breed rises or falls in fashion,--perhaps more in one district than in another, according to the state of civilization of the inhabitants,--slowly to add to the characteristic features of the breed, whatever they may be. But the chance will be infinitely small of any record having been preserved of such slow, varying, and insensible changes. I must now say a few words on the circumstances, favourable, or the reverse, to man's power of selection. A high degree of variability is obviously favourable, as freely giving the materials for selection to work on; not that mere individual differences are not amply {41} sufficient, with extreme care, to allow of the accumulation of a large amount of modification in almost any desired direction. But as variations manifestly useful or pleasing to man appear only occasionally, the chance of their appearance will be much increased by a large number of individuals being kept; and hence this comes to be of the highest importance to success. On this principle Marshall has remarked, with respect to the sheep of parts of Yorkshire, that "as they generally belong to poor people, and are mostly _in small lots_, they never can be improved." On the other hand, nurserymen, from raising large stocks of the same plants, are generally far more successful than amateurs in getting new and valuable varieties. The keeping of a large number of individuals of a species in any country requires that the species should be placed under favourable conditions of life, so as to breed freely in that country. When the individuals of any species are scanty, all the individuals, whatever their quality may be, will generally be allowed to breed, and this will effectually prevent selection. But probably the most important point of all, is, that the animal or plant should be so highly useful to man, or so much valued by him, that the closest attention should be paid to even the slightest deviation in the qualities or structure of each individual. Unless such attention be paid nothing can be effected. I have seen it gravely remarked, that it was most fortunate that the strawberry began to vary just when gardeners began to attend closely to this plant. No doubt the strawberry had always varied since it was cultivated, but the slight varieties had been neglected. As soon, however, as gardeners picked out individual plants with slightly larger, earlier, or better fruit, and raised seedlings from them, and again picked out the best seedlings and bred from them, then, there appeared (aided by some {42} crossing with distinct species) those many admirable varieties of the strawberry which have been raised during the last thirty or forty years. In the case of animals with separate sexes, facility in preventing crosses is an important element of success in the formation of new races,--at least, in a country which is already stocked with other races. In this respect enclosure of the land plays a part. Wandering savages or the inhabitants of open plains rarely possess more than one breed of the same species. Pigeons can be mated for life, and this is a great convenience to the fancier, for thus many races may be kept true, though mingled in the same aviary; and this circumstance must have largely favoured the improvement and formation of new breeds. Pigeons, I may add, can be propagated in great numbers and at a very quick rate, and inferior birds may be freely rejected, as when killed they serve for food. On the other hand, cats, from their nocturnal rambling habits, cannot be matched, and, although so much valued by women and children, we hardly ever see a distinct breed kept up; such breeds as we do sometimes see are almost always imported from some other country, often from islands. Although I do not doubt that some domestic animals vary less than others, yet the rarity or absence of distinct breeds of the cat, the donkey, peacock, goose, &c., may be attributed in main part to selection not having been brought into play: in cats, from the difficulty in pairing them; in donkeys, from only a few being kept by poor people, and little attention paid to their breeding; in peacocks, from not being very easily reared and a large stock not kept; in geese, from being valuable only for two purposes, food and feathers, and more especially from no pleasure having been felt in the display of distinct breeds. To sum up on the origin of our Domestic Races of {43} animals and plants. I believe that the conditions of life, from their action on the reproductive system, are so far of the highest importance as causing variability. I do not believe that variability is an inherent and necessary contingency, under all circumstances, with all organic beings, as some authors have thought. The effects of variability are modified by various degrees of inheritance and of reversion. Variability is governed by many unknown laws, more especially by that of correlation of growth. Something may be attributed to the direct action of the conditions of life. Something must be attributed to use and disuse. The final result is thus rendered infinitely complex. In some cases, I do not doubt that the intercrossing of species, aboriginally distinct, has played an important part in the origin of our domestic productions. When in any country several domestic breeds have once been established, their occasional intercrossing, with the aid of selection, has, no doubt, largely aided in the formation of new sub-breeds; but the importance of the crossing of varieties has, I believe, been greatly exaggerated, both in regard to animals and to those plants which are propagated by seed. In plants which are temporarily propagated by cuttings, buds, &c., the importance of the crossing both of distinct species and of varieties is immense; for the cultivator here quite disregards the extreme variability both of hybrids and mongrels, and the frequent sterility of hybrids; but the cases of plants not propagated by seed are of little importance to us, for their endurance is only temporary. Over all these causes of Change I am convinced that the accumulative action of Selection, whether applied methodically and more quickly, or unconsciously and more slowly, but more efficiently, is by far the predominant Power. * * * * * {44} CHAPTER II. VARIATION UNDER NATURE. Variability--Individual differences--Doubtful species--Wide ranging, much diffused, and common species vary most--Species of the larger genera in any country vary more than the species of the smaller genera--Many of the species of the larger genera resemble varieties in being very closely, but unequally, related to each other, and in having restricted ranges. Before applying the principles arrived at in the last chapter to organic beings in a state of nature, we must briefly discuss whether these latter are subject to any variation. To treat this subject at all properly, a long catalogue of dry facts should be given; but these I shall reserve for my future work. Nor shall I here discuss the various definitions which have been given of the term species. No one definition has as yet satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species. Generally the term includes the unknown element of a distinct act of creation. The term "variety" is almost equally difficult to define; but here community of descent is almost universally implied, though it can rarely be proved. We have also what are called monstrosities; but they graduate into varieties. By a monstrosity I presume is meant some considerable deviation of structure in one part, either injurious to or not useful to the species, and not generally propagated. Some authors use the term "variation" in a technical sense, as implying a modification directly due to the physical conditions of life; and "variations" in this sense are supposed not to be inherited: but who can say that the dwarfed condition of shells in the brackish waters of the Baltic, or dwarfed {45} plants on Alpine summits, or the thicker fur of an animal from far northwards, would not in some cases be inherited for at least some few generations? and in this case I presume that the form would be called a variety. Again, we have many slight differences which may be called individual differences, such as are known frequently to appear in the offspring from the same parents, or which may be presumed to have thus arisen, from being frequently observed in the individuals of the same species inhabiting the same confined locality. No one supposes that all the individuals of the same species are cast in the very same mould. These individual differences are highly important for us, as they afford materials for natural selection to accumulate, in the same manner as man can accumulate in any given direction individual differences in his domesticated productions. These individual differences generally affect what naturalists consider unimportant parts; but I could show by a long catalogue of facts, that parts which must be called important, whether viewed under a physiological or classificatory point of view, sometimes vary in the individuals of the same species. I am convinced that the most experienced naturalist would be surprised at the number of the cases of variability, even in important parts of structure, which he could collect on good authority, as I have collected, during a course of years. It should be remembered that systematists are far from pleased at finding variability in important characters, and that there are not many men who will laboriously examine internal and important organs, and compare them in many specimens of the same species. I should never have expected that the branching of the main nerves close to the great central ganglion of an insect would have been variable in the same species; I should have expected that changes of this nature could have been effected only {46} by slow degrees: yet quite recently Mr. Lubbock has shown a degree of variability in these main nerves in Coccus, which may almost be compared to the irregular branching of the stem of a tree. This philosophical naturalist, I may add, has also quite recently shown that the muscles in the larvæ of certain insects are very far from uniform. Authors sometimes argue in a circle when they state that important organs never vary; for these same authors practically rank that character as important (as some few naturalists have honestly confessed) which does not vary; and, under this point of view, no instance of an important part varying will ever be found: but under any other point of view many instances assuredly can be given. There is one point connected with individual differences, which seems to me extremely perplexing: I refer to those genera which have sometimes been called "protean" or "polymorphic," in which the species present an inordinate amount of variation; and hardly two naturalists can agree which forms to rank as species and which as varieties. We may instance Rubus, Rosa, and Hieracium amongst plants, several genera of insects, and several genera of Brachiopod shells. In most polymorphic genera some of the species have fixed and definite characters. Genera which are polymorphic in one country seem to be, with some few exceptions, polymorphic in other countries, and likewise, judging from Brachiopod shells, at former periods of time. These facts seem to be very perplexing, for they seem to show that this kind of variability is independent of the conditions of life. I am inclined to suspect that we see in these polymorphic genera variations in points of structure which are of no service or disservice to the species, and which consequently have not been seized on and rendered definite by natural selection, as hereafter will be explained. {47} Those forms which possess in some considerable degree the character of species, but which are so closely similar to some other forms, or are so closely linked to them by intermediate gradations, that naturalists do not like to rank them as distinct species, are in several respects the most important for us. We have every reason to believe that many of these doubtful and closely-allied forms have permanently retained their characters in their own country for a long time; for as long, as far as we know, as have good and true species. Practically, when a naturalist can unite two forms together by others having intermediate characters, he treats the one as a variety of the other, ranking the most common, but sometimes the one first described, as the species, and the other as the variety. But cases of great difficulty, which I will not here enumerate, sometimes occur in deciding whether or not to rank one form as a variety of another, even when they are closely connected by intermediate links; nor will the commonly-assumed hybrid nature of the intermediate links always remove the difficulty. In very many cases, however, one form is ranked as a variety of another, not because the intermediate links have actually been found, but because analogy leads the observer to suppose either that they do now somewhere exist, or may formerly have existed; and here a wide door for the entry of doubt and conjecture is opened. Hence, in determining whether a form should be ranked as a species or a variety, the opinion of naturalists having sound judgment and wide experience seems the only guide to follow. We must, however, in many cases, decide by a majority of naturalists, for few well-marked and well-known varieties can be named which have not been ranked as species by at least some competent judges. {48} That varieties of this doubtful nature are far from uncommon cannot be disputed. Compare the several floras of Great Britain, of France or of the United States, drawn up by different botanists, and see what a surprising number of forms have been ranked by one botanist as good species, and by another as mere varieties. Mr. H. C. Watson, to whom I lie under deep obligation for assistance of all kinds, has marked for me 182 British plants, which are generally considered as varieties, but which have all been ranked by botanists as species; and in making this list he has omitted many trifling varieties, but which nevertheless have been ranked by some botanists as species, and he has entirely omitted several highly polymorphic genera. Under genera, including the most polymorphic forms, Mr. Babington gives 251 species, whereas Mr. Bentham gives only 112,--a difference of 139 doubtful forms! Amongst animals which unite for each birth, and which are highly locomotive, doubtful forms, ranked by one zoologist as a species and by another as a variety, can rarely be found within the same country, but are common in separated areas. How many of those birds and insects in North America and Europe, which differ very slightly from each other, have been ranked by one eminent naturalist as undoubted species, and by another as varieties, or, as they are often called, as geographical races! Many years ago, when comparing, and seeing others compare, the birds from the separate islands of the Galapagos Archipelago, both one with another, and with those from the American mainland, I was much struck how entirely vague and arbitrary is the distinction between species and varieties. On the islets of the little Madeira group there are many insects which are characterized as varieties in Mr. Wollaston's admirable work, but which it cannot {49} be doubted would be ranked as distinct species by many entomologists. Even Ireland has a few animals, now generally regarded as varieties, but which have been ranked as species by some zoologists. Several most experienced ornithologists consider our British red grouse as only a strongly-marked race of a Norwegian species, whereas the greater number rank it as an undoubted species peculiar to Great Britain. A wide distance between the homes of two doubtful forms leads many naturalists to rank both as distinct species; but what distance, it has been well asked, will suffice? if that between America and Europe is ample, will that between the Continent and the Azores, or Madeira, or the Canaries, or Ireland, be sufficient? It must be admitted that many forms, considered by highly-competent judges as varieties, have so perfectly the character of species that they are ranked by other highly-competent judges as good and true species. But to discuss whether they are rightly called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air. Many of the cases of strongly-marked varieties or doubtful species well deserve consideration; for several interesting lines of argument, from geographical distribution, analogical variation, hybridism, &c., have been brought to bear on the attempt to determine their rank. I will here give only a single instance,--the well-known one of the primrose and cowslip, or Primula vulgaris and veris. These plants differ considerably in appearance; they have a different flavour, and emit a different odour; they flower at slightly different periods; they grow in somewhat different stations; they ascend mountains to different heights; they have different geographical ranges; and lastly, according to very numerous experiments made during several years by {50} that most careful observer Gärtner, they can be crossed only with much difficulty. We could hardly wish for better evidence of the two forms being specifically distinct. On the other hand, they are united by many intermediate links, and it is very doubtful whether these links are hybrids; and there is, as it seems to me, an overwhelming amount of experimental evidence, showing that they descend from common parents, and consequently must be ranked as varieties. Close investigation, in most cases, will bring naturalists to an agreement how to rank doubtful forms. Yet it must be confessed that it is in the best-known countries that we find the greatest number of forms of doubtful value. I have been struck with the fact, that if any animal or plant in a state of nature be highly useful to man, or from any cause closely attract his attention, varieties of it will almost universally be found recorded. These varieties, moreover, will be often ranked by some authors as species. Look at the common oak, how closely it has been studied; yet a German author makes more than a dozen species out of forms, which are very generally considered as varieties; and in this country the highest botanical authorities and practical men can be quoted to show that the sessile and pedunculated oaks are either good and distinct species or mere varieties. When a young naturalist commences the study of a group of organisms quite unknown to him, he is at first much perplexed to determine what differences to consider as specific, and what as varieties; for he knows nothing of the amount and kind of variation to which the group is subject; and this shows, at least, how very generally there is some variation. But if he confine his attention to one class within one country, he will soon make up his mind how to rank most of the doubtful forms. His {51} general tendency will be to make many species, for he will become impressed, just like the pigeon or poultry fancier before alluded to, with the amount of difference in the forms which he is continually studying; and he has little general knowledge of analogical variation in other groups and in other countries, by which to correct his first impressions. As he extends the range of his observations, he will meet with more cases of difficulty; for he will encounter a greater number of closely-allied forms. But if his observations be widely extended, he will in the end generally be enabled to make up his own mind which to call varieties and which species; but he will succeed in this at the expense of admitting much variation,--and the truth of this admission will often be disputed by other naturalists. When, moreover, he comes to study allied forms brought from countries not now continuous, in which case he can hardly hope to find the intermediate links between his doubtful forms, he will have to trust almost entirely to analogy, and his difficulties rise to a climax. Certainly no clear line of demarcation has as yet been drawn between species and sub-species--that is, the forms which in the opinion of some naturalists come very near to, but do not quite arrive at the rank of species; or, again, between sub-species and well-marked varieties, or between lesser varieties and individual differences. These differences blend into each other in an insensible series; and a series impresses the mind with the idea of an actual passage. Hence I look at individual differences, though of small interest to the systematist, as of high importance for us, as being the first step towards such slight varieties as are barely thought worth recording in works on natural history. And I look at varieties which are in any degree more distinct and permanent, as steps leading to more {52} strongly marked and more permanent varieties; and at these latter, as leading to sub-species, and to species. The passage from one stage of difference to another and higher stage may be, in some cases, due merely to the long-continued action of different physical conditions in two different regions; but I have not much faith in this view; and I attribute the passage of a variety, from a state in which it differs very slightly from its parent to one in which it differs more, to the action of natural selection in accumulating (as will hereafter be more fully explained) differences of structure in certain definite directions. Hence I believe a well-marked variety may be called an incipient species; but whether this belief be justifiable must be judged of by the general weight of the several facts and views given throughout this work. It need not be supposed that all varieties or incipient species necessarily attain the rank of species. They may whilst in this incipient state become extinct, or they may endure as varieties for very long periods, as has been shown to be the case by Mr. Wollaston with the varieties of certain fossil land-shells in Madeira. If a variety were to flourish so as to exceed in numbers the parent species, it would then rank as the species, and the species as the variety; or it might come to supplant and exterminate the parent species; or both might co-exist, and both rank as independent species. But we shall hereafter have to return to this subject. From these remarks it will be seen that I look at the term species, as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety, which is given to less distinct and more fluctuating forms. The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, and for mere convenience' sake. {53} Guided by theoretical considerations, I thought that some interesting results might be obtained in regard to the nature and relations of the species which vary most, by tabulating all the varieties in several well-worked floras. At first this seemed a simple task; but Mr. H. C. Watson, to whom I am much indebted for valuable advice and assistance on this subject, soon convinced me that there were many difficulties, as did subsequently Dr. Hooker, even in stronger terms. I shall reserve for my future work the discussion of these difficulties, and the tables themselves of the proportional numbers of the varying species. Dr. Hooker permits me to add, that after having carefully read my manuscript, and examined the tables, he thinks that the following statements are fairly well established. The whole subject, however, treated as it necessarily here is with much brevity, is rather perplexing, and allusions cannot be avoided to the "struggle for existence," "divergence of character," and other questions, hereafter to be discussed. Alph. de Candolle and others have shown that plants which have very wide ranges generally present varieties; and this might have been expected, as they become exposed to diverse physical conditions, and as they come into competition (which, as we shall hereafter see, is a far more important circumstance) with different sets of organic beings. But my tables further show that, in any limited country, the species which are most common, that is abound most in individuals, and the species which are most widely diffused within their own country (and this is a different consideration from wide range, and to a certain extent from commonness), often give rise to varieties sufficiently well-marked to have been recorded in botanical works. Hence it is the most flourishing, or, as they may be called, the dominant species,--those {54} which range widely over the world, are the most diffused in their own country, and are the most numerous in individuals,--which oftenest produce well-marked varieties, or, as I consider them, incipient species. And this, perhaps, might have been anticipated; for, as varieties, in order to become in any degree permanent, necessarily have to struggle with the other inhabitants of the country, the species which are already dominant will be the most likely to yield offspring, which, though in some slight degree modified, still inherit those advantages that enabled their parents to become dominant over their compatriots. If the plants inhabiting a country and described in any Flora be divided into two equal masses, all those in the larger genera being placed on one side, and all those in the smaller genera on the other side, a somewhat larger number of the very common and much diffused or dominant species will be found on the side of the larger genera. This, again, might have been anticipated; for the mere fact of many species of the same genus inhabiting any country, shows that there is something in the organic or inorganic conditions of that country favourable to the genus; and, consequently, we might have expected to have found in the larger genera, or those including many species, a large proportional number of dominant species. But so many causes tend to obscure this result, that I am surprised that my tables show even a small majority on the side of the larger genera. I will here allude to only two causes of obscurity. Fresh-water and salt-loving plants have generally very wide ranges and are much diffused, but this seems to be connected with the nature of the stations inhabited by them, and has little or no relation to the size of the genera to which the species belong. Again, plants low in the scale of organisation are {55} generally much more widely diffused than plants higher in the scale; and here again there is no close relation to the size of the genera. The cause of lowly-organised plants ranging widely will be discussed in our chapter on geographical distribution. From looking at species as only strongly-marked and well-defined varieties, I was led to anticipate that the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera; for wherever many closely related species (_i.e._ species of the same genus) have been formed, many varieties or incipient species ought, as a general rule, to be now forming. Where many large trees grow, we expect to find saplings. Where many species of a genus have been formed through variation, circumstances have been favourable for variation; and hence we might expect that the circumstances would generally be still favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group having many species, than in one having few. To test the truth of this anticipation I have arranged the plants of twelve countries, and the coleopterous insects of two districts, into two nearly equal masses, the species of the larger genera on one side, and those of the smaller genera on the other side, and it has invariably proved to be the case that a larger proportion of the species on the side of the larger genera present varieties, than on the side of the smaller genera. Moreover, the species of the large genera which present any varieties, invariably present a larger average number of varieties than do the species of the small genera. Both these results follow when another division is made, and when all the smallest genera, with from only one to four species, are absolutely excluded from the tables. These {56} facts are of plain signification on the view that species are only strongly marked and permanent varieties; for wherever many species of the same genus have been formed, or where, if we may use the expression, the manufactory of species has been active, we ought generally to find the manufactory still in action, more especially as we have every reason to believe the process of manufacturing new species to be a slow one. And this certainly is the case, if varieties be looked at as incipient species; for my tables clearly show as a general rule that, wherever many species of a genus have been formed, the species of that genus present a number of varieties, that is of incipient species beyond the average. It is not that all large genera are now varying much, and are thus increasing in the number of their species, or that no small genera are now varying and increasing; for if this had been so, it would have been fatal to my theory; inasmuch as geology plainly tells us that small genera have in the lapse of time often increased greatly in size; and that large genera have often come to their maxima, declined, and disappeared. All that we want to show is, that where many species of a genus have been formed, on an average many are still forming; and this holds good. There are other relations between the species of large genera and their recorded varieties which deserve notice. We have seen that there is no infallible criterion by which to distinguish species and well-marked varieties; and in those cases in which intermediate links have not been found between doubtful forms, naturalists are compelled to come to a determination by the amount of difference between them, judging by analogy whether or not the amount suffices to raise one or both to the rank of species. Hence the amount of difference is one very important criterion in settling whether two forms {57} should be ranked as species or varieties. Now Fries has remarked in regard to plants, and Westwood in regard to insects, that in large genera the amount of difference between the species is often exceedingly small. I have endeavoured to test this numerically by averages, and, as far as my imperfect results go, they confirm the view. I have also consulted some sagacious and experienced observers, and, after deliberation, they concur in this view. In this respect, therefore, the species of the larger genera resemble varieties, more than do the species of the smaller genera. Or the case may be put in another way, and it may be said, that in the larger genera, in which a number of varieties or incipient species greater than the average are now manufacturing, many of the species already manufactured still to a certain extent resemble varieties, for they differ from each other by a less than usual amount of difference. Moreover, the species of the large genera are related to each other, in the same manner as the varieties of any one species are related to each other. No naturalist pretends that all the species of a genus are equally distinct from each other; they may generally be divided into sub-genera, or sections, or lesser groups. As Fries has well remarked, little groups of species are generally clustered like satellites around certain other species. And what are varieties but groups of forms, unequally related to each other, and clustered round certain forms--that is, round their parent-species? Undoubtedly there is one most important point of difference between varieties and species; namely, that the amount of difference between varieties, when compared with each other or with their parent-species, is much less than that between the species of the same genus. But when we come to discuss the principle, as I call it, of Divergence of Character, {58} we shall see how this may be explained, and how the lesser differences between varieties will tend to increase into the greater differences between species. There is one other point which seems to me worth notice. Varieties generally have much restricted ranges: this statement is indeed scarcely more than a truism, for if a variety were found to have a wider range than that of its supposed parent-species, their denominations ought to be reversed. But there is also reason to believe, that those species which are very closely allied to other species, and in so far resemble varieties, often have much restricted ranges. For instance, Mr. H. C. Watson has marked for me in the well-sifted London Catalogue of plants (4th edition) 63 plants which are therein ranked as species, but which he considers as so closely allied to other species as to be of doubtful value: these 63 reputed species range on an average over 6.9 of the provinces into which Mr. Watson has divided Great Britain. Now, in this same catalogue, 53 acknowledged varieties are recorded, and these range over 7.7 provinces; whereas, the species to which these varieties belong range over 14.3 provinces. So that the acknowledged varieties have very nearly the same restricted average range, as have those very closely allied forms, marked for me by Mr. Watson as doubtful species, but which are almost universally ranked by British botanists as good and true species. Finally, then, varieties have the same general characters as species, for they cannot be distinguished from species,--except, firstly, by the discovery of intermediate linking forms, and the occurrence of such links cannot affect the actual characters of the forms which they connect; and except, secondly by a certain amount of {59} difference, for two forms, if differing very little, are generally ranked as varieties, notwithstanding that intermediate linking forms have not been discovered; but the amount of difference considered necessary to give to two forms the rank of species is quite indefinite. In genera having more than the average number of species in any country, the species of these genera have more than the average number of varieties. In large genera the species are apt to be closely, but unequally allied together, forming little clusters round certain species. Species very closely allied to other species apparently have restricted ranges. In all these several respects the species of large genera present a strong analogy with varieties. And we can clearly understand these analogies, if species have once existed as varieties, and have thus originated: whereas, these analogies are utterly inexplicable if each species has been independently created. We have, also, seen that it is the most flourishing or dominant species of the larger genera which on an average vary most; and varieties, as we shall hereafter see, tend to become converted into new and distinct species. The larger genera thus tend to become larger; and throughout nature the forms of life which are now dominant tend to become still more dominant by leaving many modified and dominant descendants. But by steps hereafter to be explained, the larger genera also tend to break up into smaller genera. And thus, the forms of life throughout the universe become divided into groups subordinate to groups. * * * * * {60} CHAPTER III. STRUGGLE FOR EXISTENCE. Bears on natural selection--The term used in a wide sense--Geometrical powers of increase--Rapid increase of naturalised animals and plants--Nature of the checks to increase--Competition universal--Effects of climate--Protection from the number of individuals--Complex relations of all animals and plants throughout nature--Struggle for life most severe between individuals and varieties of the same species; often severe between species of the same genus--The relation of organism to organism the most important of all relations. Before entering on the subject of this chapter, I must make a few preliminary remarks, to show how the struggle for existence bears on Natural Selection. It has been seen in the last chapter that amongst organic beings in a state of nature there is some individual variability: indeed I am not aware that this has ever been disputed. It is immaterial for us whether a multitude of doubtful forms be called species or sub-species or varieties; what rank, for instance, the two or three hundred doubtful forms of British plants are entitled to hold, if the existence of any well-marked varieties be admitted. But the mere existence of individual variability and of some few well-marked varieties, though necessary as the foundation for the work, helps us but little in understanding how species arise in nature. How have all those exquisite adaptations of one part of the organisation to another part, and to the conditions of life, and of one distinct organic being to another being, been perfected? We see these beautiful co-adaptations most {61} plainly in the woodpecker and missletoe; and only a little less plainly in the humblest parasite which clings to the hairs of a quadruped or feathers of a bird; in the structure of the beetle which dives through the water; in the plumed seed which is wafted by the gentlest breeze; in short, we see beautiful adaptations everywhere and in every part of the organic world. Again, it may be asked, how is it that varieties, which I have called incipient species, become ultimately converted into good and distinct species, which in most cases obviously differ from each other far more than do the varieties of the same species? How do those groups of species, which constitute what are called distinct genera, and which differ from each other more than do the species of the same genus, arise? All these results, as we shall more fully see in the next chapter, follow from the struggle for life. Owing to this struggle for life, any variation, however slight, and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relations to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection, in order to mark its relation to man's power of selection. We have seen that man by selection can certainly produce great results, and can adapt organic beings to his own uses, through the accumulation of slight but useful variations, given to him by the hand of Nature. But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as {62} immeasurably superior to man's feeble efforts, as the works of Nature are to those of Art. We will now discuss in a little more detail the struggle for existence. In my future work this subject shall be treated, as it well deserves, at much greater length. The elder de Candolle and Lyell have largely and philosophically shown that all organic beings are exposed to severe competition. In regard to plants, no one has treated this subject with more spirit and ability than W. Herbert, Dean of Manchester, evidently the result of his great horticultural knowledge. Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult--at least I have found it so--than constantly to bear this conclusion in mind. Yet unless it be thoroughly engrained in the mind, I am convinced that the whole economy of nature, with every fact on distribution, rarity, abundance, extinction, and variation, will be dimly seen or quite misunderstood. We behold the face of nature bright with gladness, we often see superabundance of food; we do not see, or we forget that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that though food may be now superabundant, it is not so at all seasons of each recurring year. I should premise that I use the term Struggle for Existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny. Two canine animals in a time of dearth, may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle {63} for life against the drought, though more properly it should be said to be dependent on the moisture. A plant which annually produces a thousand seeds, of which on an average only one comes to maturity, may be more truly said to struggle with the plants of the same and other kinds which already clothe the ground. The missletoe is dependent on the apple and a few other trees, but can only in a far-fetched sense be said to struggle with these trees, for if too many of these parasites grow on the same tree, it will languish and die. But several seedling missletoes, growing close together on the same branch, may more truly be said to struggle with each other. As the missletoe is disseminated by birds, its existence depends on birds; and it may metaphorically be said to struggle with other fruit-bearing plants, in order to tempt birds to devour and thus disseminate its seeds rather than those of other plants. In these several senses, which pass into each other, I use for convenience' sake the general term of struggle for existence. A struggle for existence inevitably follows from the high rate at which all organic beings tend to increase. Every being, which during its natural lifetime produces several eggs or seeds, must suffer destruction during some period of its life, and during some season or occasional year, otherwise, on the principle of geometrical increase, its numbers would quickly become so inordinately great that no country could support the product. Hence, as more individuals are produced than can possibly survive, there must in every case be a struggle for existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life. It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms; for in this case there {64} can be no artificial increase of food, and no prudential restraint from marriage. Although some species may be now increasing, more or less rapidly, in numbers, all cannot do so, for the world would not hold them. There is no exception to the rule that every organic being naturally increases at so high a rate, that if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in a few thousand years, there would literally not be standing room for his progeny. Linnæus has calculated that if an annual plant produced only two seeds--and there is no plant so unproductive as this--and their seedlings next year produced two, and so on, then in twenty years there would be a million plants. The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase: it will be under the mark to assume that it breeds when thirty years old, and goes on breeding till ninety years old, bringing forth three pair of young in this interval; if this be so, at the end of the fifth century there would be alive fifteen million elephants, descended from the first pair. But we have better evidence on this subject than mere theoretical calculations, namely, the numerous recorded cases of the astonishingly rapid increase of various animals in a state of nature, when circumstances have been favourable to them during two or three following seasons. Still more striking is the evidence from our domestic animals of many kinds which have run wild in several parts of the world: if the statements of the rate of increase of slow-breeding cattle and horses in South America, and latterly in Australia, had not been well authenticated, they would have been incredible. So it is with plants: cases could be given of {65} introduced plants which have become common throughout whole islands in a period of less than ten years. Several of the plants, such as the cardoon and a tall thistle, now most numerous over the wide plains of La Plata, clothing square leagues of surface almost to the exclusion of all other plants, have been introduced from Europe; and there are plants which now range in India, as I hear from Dr. Falconer, from Cape Comorin to the Himalaya, which have been imported from America since its discovery. In such cases, and endless instances could be given, no one supposes that the fertility of these animals or plants has been suddenly and temporarily increased in any sensible degree. The obvious explanation is that the conditions of life have been very favourable, and that there has consequently been less destruction of the old and young, and that nearly all the young have been enabled to breed. In such cases the geometrical ratio of increase, the result of which never fails to be surprising, simply explains the extraordinarily rapid increase and wide diffusion of naturalised productions in their new homes. In a state of nature almost every plant produces seed, and amongst animals there are very few which do not annually pair. Hence we may confidently assert, that all plants and animals are tending to increase at a geometrical ratio, that all would most rapidly stock every station in which they could any how exist, and that the geometrical tendency to increase must be checked by destruction at some period of life. Our familiarity with the larger domestic animals tends, I think, to mislead us: we see no great destruction falling on them, and we forget that thousands are annually slaughtered for food, and that in a state of nature an equal number would have somehow to be disposed of. The only difference between organisms which annually {66} produce eggs or seeds by the thousand, and those which produce extremely few, is, that the slow-breeders would require a few more years to people, under favourable conditions, a whole district, let it be ever so large. The condor lays a couple of eggs and the ostrich a score, and yet in the same country the condor may be the more numerous of the two: the Fulmar petrel lays but one egg, yet it is believed to be the most numerous bird in the world. One fly deposits hundreds of eggs, and another, like the hippobosca, a single one; but this difference does not determine how many individuals of the two species can be supported in a district. A large number of eggs is of some importance to those species which depend on a rapidly fluctuating amount of food, for it allows them rapidly to increase in number. But the real importance of a large number of eggs or seeds is to make up for much destruction at some period of life; and this period in the great majority of cases is an early one. If an animal can in any way protect its own eggs or young, a small number may be produced, and yet the average stock be fully kept up; but if many eggs or young are destroyed, many must be produced, or the species will become extinct. It would suffice to keep up the full number of a tree, which lived on an average for a thousand years, if a single seed were produced once in a thousand years, supposing that this seed were never destroyed, and could be ensured to germinate in a fitting place. So that in all cases, the average number of any animal or plant depends only indirectly on the number of its eggs or seeds. In looking at Nature, it is most necessary to keep the foregoing considerations always in mind--never to forget that every single organic being around us may be said to be striving to the utmost to increase in numbers; that each lives by a struggle at some period of {67} its life; that heavy destruction inevitably falls either on the young or old, during each generation or at recurrent intervals. Lighten any check, mitigate the destruction ever so little, and the number of the species will almost instantaneously increase to any amount. The causes which check the natural tendency of each species to increase in number are most obscure. Look at the most vigorous species; by as much as it swarms in numbers, by so much will its tendency to increase be still further increased. We know not exactly what the checks are in even one single instance. Nor will this surprise any one who reflects how ignorant we are on this head, even in regard to mankind, so incomparably better known than any other animal. This subject has been ably treated by several authors, and I shall, in my future work, discuss some of the checks at considerable length, more especially in regard to the feral animals of South America. Here I will make only a few remarks, just to recall to the reader's mind some of the chief points. Eggs or very young animals seem generally to suffer most, but this is not invariably the case. With plants there is a vast destruction of seeds, but, from some observations which I have made, I believe that it is the seedlings which suffer most from germinating in ground already thickly stocked with other plants. Seedlings, also, are destroyed in vast numbers by various enemies; for instance, on a piece of ground three feet long and two wide, dug and cleared, and where there could be no choking from other plants, I marked all the seedlings of our native weeds as they came up, and out of the 357 no less than 295 were destroyed, chiefly by slugs and insects. If turf which has long been mown, and the case would be the same with turf closely browsed by quadrupeds, be let to grow, the more vigorous plants {68} gradually kill the less vigorous, though fully grown, plants: thus out of twenty species growing on a little plot of turf (three feet by four) nine species perished from the other species being allowed to grow up freely. The amount of food for each species of course gives the extreme limit to which each can increase; but very frequently it is not the obtaining food, but the serving as prey to other animals, which determines the average numbers of a species. Thus, there seems to be little doubt that the stock of partridges, grouse, and hares on any large estate depends chiefly on the destruction of vermin. If not one head of game were shot during the next twenty years in England, and, at the same time, if no vermin were destroyed, there would, in all probability, be less game than at present, although hundreds of thousands of game animals are now annually killed. On the other hand, in some cases, as with the elephant and rhinoceros, none are destroyed by beasts of prey: even the tiger in India most rarely dares to attack a young elephant protected by its dam. Climate plays an important part in determining the average numbers of a species, and periodical seasons of extreme cold or drought, I believe to be the most effective of all checks. I estimated that the winter of 1854-55 destroyed four-fifths of the birds in my own grounds; and this is a tremendous destruction, when we remember that ten per cent, is an extraordinarily severe mortality from epidemics with man. The action of climate seems at first sight to be quite independent of the struggle for existence; but in so far as climate chiefly acts in reducing food, it brings on the most severe struggle between the individuals, whether of the same or of distinct species, which subsist on the same kind of food. Even when climate, for instance extreme cold, {69} acts directly, it will be the least vigorous, or those which have got least food through the advancing winter, which will suffer most. When we travel from south to north, or from a damp region to a dry, we invariably see some species gradually getting rarer and rarer, and finally disappearing; and the change of climate being conspicuous, we are tempted to attribute the whole effect to its direct action. But this is a false view: we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food; and if these enemies or competitors be in the least degree favoured by any slight change of climate, they will increase in numbers, and, as each area is already fully stocked with inhabitants, the other species will decrease. When we travel southward and see a species decreasing in numbers, we may feel sure that the cause lies quite as much in other species being favoured, as in this one being hurt. So it is when we travel northward, but in a somewhat lesser degree, for the number of species of all kinds, and therefore of competitors, decreases northwards; hence in going northward, or in ascending a mountain, we far oftener meet with stunted forms, due to the _directly_ injurious action of climate, than we do in proceeding southwards or in descending a mountain. When we reach the Arctic regions, or snow-capped summits, or absolute deserts, the struggle for life is almost exclusively with the elements. That climate acts in main part indirectly by favouring other species, we may clearly see in the prodigious number of plants in our gardens which can perfectly well endure our climate, but which never become naturalised, for they cannot compete with our native plants nor resist destruction by our native animals. {70} When a species, owing to highly favourable circumstances, increases inordinately in numbers in a small tract, epidemics--at least, this seems generally to occur with our game animals--often ensue: and here we have a limiting check independent of the struggle for life. But even some of these so-called epidemics appear to be due to parasitic worms, which have from some cause, possibly in part through facility of diffusion amongst the crowded animals, been disproportionably favoured: and here comes in a sort of struggle between the parasite and its prey. On the other hand, in many cases, a large stock of individuals of the same species, relatively to the numbers of its enemies, is absolutely necessary for its preservation. Thus we can easily raise plenty of corn and rape-seed, &c., in our fields, because the seeds are in great excess compared with the number of birds which feed on them; nor can the birds, though having a superabundance of food at this one season, increase in number proportionally to the supply of seed, as their numbers are checked during winter: but any one who has tried, knows how troublesome it is to get seed from a few wheat or other such plants in a garden: I have in this case lost every single seed. This view of the necessity of a large stock of the same species for its preservation, explains, I believe, some singular facts in nature, such as that of very rare plants being sometimes extremely abundant in the few spots where they do occur; and that of some social plants being social, that is, abounding in individuals, even on the extreme confines of their range. For in such cases, we may believe, that a plant could exist only where the conditions of its life were so favourable that many could exist together, and thus save the species from utter destruction. I should add that the good effects of frequent intercrossing, and {71} the ill effects of close interbreeding, probably come into play in some of these cases; but on this intricate subject I will not here enlarge. Many cases are on record showing how complex and unexpected are the checks and relations between organic beings, which have to struggle together in the same country. I will give only a single instance, which, though a simple one, has interested me. In Staffordshire, on the estate of a relation, where I had ample means of investigation, there was a large and extremely barren heath, which had never been touched by the hand of man; but several hundred acres of exactly the same nature had been enclosed twenty-five years previously and planted with Scotch fir. The change in the native vegetation of the planted part of the heath was most remarkable, more than is generally seen in passing from one quite different soil to another: not only the proportional numbers of the heath-plants were wholly changed, but twelve species of plants (not counting grasses and carices) flourished in the plantations, which could not be found on the heath. The effect on the insects must have been still greater, for six insectivorous birds were very common in the plantations, which were not to be seen on the heath; and the heath was frequented by two or three distinct insectivorous birds. Here we see how potent has been the effect of the introduction of a single tree, nothing whatever else having been done, with the exception that the land had been enclosed, so that cattle could not enter. But how important an element enclosure is, I plainly saw near Farnham, in Surrey. Here there are extensive heaths, with a few clumps of old Scotch firs on the distant hill-tops: within the last ten years large spaces have been enclosed, and self-sown firs are now springing up in multitudes, so close together that all cannot live. {72} When I ascertained that these young trees had not been sown or planted, I was so much surprised at their numbers that I went to several points of view, whence I could examine hundreds of acres of the unenclosed heath, and literally I could not see a single Scotch fir, except the old planted clumps. But on looking closely between the stems of the heath, I found a multitude of seedlings and little trees, which had been perpetually browsed down by the cattle. In one square yard, at a point some hundred yards distant from one of the old clumps, I counted thirty-two little trees; and one of them, with twenty-six rings of growth, had during many years tried to raise its head above the stems of the heath, and had failed. No wonder that, as soon as the land was enclosed, it became thickly clothed with vigorously growing young firs. Yet the heath was so extremely barren and so extensive that no one would ever have imagined that cattle would have so closely and effectually searched it for food. Here we see that cattle absolutely determine the existence of the Scotch fir; but in several parts of the world insects determine the existence of cattle. Perhaps Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater number in Paraguay of a certain fly, which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers are probably regulated by hawks or beasts of prey) were to increase in Paraguay, the flies would decrease--then cattle and horses would became feral, and this would certainly greatly {73} alter (as indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects; and this, as we just have seen in Staffordshire, the insectivorous birds, and so onwards in ever-increasing circles of complexity. We began this series by insectivorous birds, and we have ended with them, Not that in nature the relations can ever be as simple as this. Battle within battle must ever be recurring with varying success; and yet in the long-run the forces are so nicely balanced, that the face of nature remains uniform for long periods of time, though assuredly the merest trifle would often give the victory to one organic being over another. Nevertheless so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life! I am tempted to give one more instance showing how plants and animals, most remote in the scale of nature, are bound together by a web of complex relations. I shall hereafter have occasion to show that the exotic Lobelia fulgens, in this part of England, is never visited by insects, and consequently, from its peculiar structure, never can set a seed. Many of our orchidaceous plants absolutely require the visits of moths to remove their pollen-masses and thus to fertilise them. I have, also, reason to believe that humble-bees are indispensable to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower. From experiments which I have lately tried, I have found that the visits of bees are necessary for the fertilisation of some kinds of clover; but humble-bees alone visit the red clover (Trifolium pratense), as other bees cannot reach the nectar. Hence I have very little doubt, that if the {74} whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests; and Mr. H. Newman, who has long attended to the habits of humble-bees, believes that "more than two-thirds of them are thus destroyed all over England." Now the number of mice is largely dependent, as every one knows, on the number of cats; and Mr. Newman says, "Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice." Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district! In the case of every species, many different checks, acting at different periods of life, and during different seasons or years, probably come into play; some one check or some few being generally the most potent, but all concur in determining the average number or even the existence of the species. In some cases it can be shown that widely-different checks act on the same species in different districts. When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this! Every one has heard that when an American forest is cut down, a very different vegetation springs up; but it has been observed that ancient Indian ruins in the Southern United States, which must formerly have been cleared of trees, now display the same beautiful diversity and proportion of kinds as in the surrounding {75} virgin forests. What a struggle between the several kinds of trees must here have gone on during long centuries, each annually scattering its seeds by the thousand; what war between insect and insect--between insects, snails, and other animals with birds and beasts of prey--all striving to increase, and all feeding on each other or on the trees or their seeds and seedlings, or on the other plants which first clothed the ground and thus checked the growth of the trees! Throw up a handful of feathers, and all must fall to the ground according to definite laws; but how simple is this problem compared to the action and reaction of the innumerable plants and animals which have determined, in the course of centuries, the proportional numbers and kinds of trees now growing on the old Indian ruins! The dependency of one organic being on another, as of a parasite on its prey, lies generally between beings remote in the scale of nature. This is often the case with those which may strictly be said to struggle with each other for existence, as in the case of locusts and grass-feeding quadrupeds. But the struggle almost invariably will be most severe between the individuals of the same species, for they frequent the same districts, require the same food, and are exposed to the same dangers. In the case of varieties of the same species, the struggle will generally be almost equally severe, and we sometimes see the contest soon decided; for instance, if several varieties of wheat be sown together, and the mixed seed be resown, some of the varieties which best suit the soil or climate, or are naturally the most fertile, will beat the others and so yield more seed, and will consequently in a few years quite supplant the other varieties. To keep up a mixed stock of even such extremely close varieties as the variously {76} coloured sweet-peas, they must be each year harvested separately, and the seed then mixed in due proportion, otherwise the weaker kinds will steadily decrease in numbers and disappear. So again with the varieties of sheep: it has been asserted that certain mountain-varieties will starve out other mountain-varieties, so that they cannot be kept together. The same result has followed from keeping together different varieties of the medicinal leech. It may even be doubted whether the varieties of any one of our domestic plants or animals have so exactly the same strength, habits, and constitution, that the original proportions of a mixed stock could be kept up for half-a-dozen generations, if they were allowed to struggle together, like beings in a state of nature, and if the seed or young were not annually sorted. As species of the same genus have usually, though by no means invariably, some similarity in habits and constitution, and always in structure, the struggle will generally be more severe between species of the same genus, when they come into competition with each other, than between species of distinct genera. We see this in the recent extension over parts of the United States of one species of swallow having caused the decrease of another species. The recent increase of the missel-thrush in parts of Scotland has caused the decrease of the song-thrush. How frequently we hear of one species of rat taking the place of another species under the most different climates! In Russia the small Asiatic cockroach has everywhere driven before it its great congener. One species of charlock will supplant another, and so in other cases. We can dimly see why the competition should be most severe between allied forms, which fill nearly the same place in the economy of nature; {77} but probably in no one case could we precisely say why one species has been victorious over another in the great battle of life. A corollary of the highest importance may be deduced from the foregoing remarks, namely, that the structure of every organic being is related, in the most essential yet often hidden manner, to that of all other organic beings, with which it comes into competition for food or residence, or from which it has to escape, or on which it preys. This is obvious in the structure of the teeth and talons of the tiger; and in that of the legs and claws of the parasite which clings to the hair on the tiger's body. But in the beautifully plumed seed of the dandelion, and in the flattened and fringed legs of the water-beetle, the relation seems at first confined to the elements of air and water. Yet the advantage of plumed seeds no doubt stands in the closest relation to the land being already thickly clothed by other plants; so that the seeds may be widely distributed and fall on unoccupied ground. In the water-beetle, the structure of its legs, so well adapted for diving, allows it to compete with other aquatic insects, to hunt for its own prey, and to escape serving as prey to other animals. The store of nutriment laid up within the seeds of many plants seems at first sight to have no sort of relation to other plants. But from the strong growth of young plants produced from such seeds (as peas and beans), when sown in the midst of long grass, I suspect that the chief use of the nutriment in the seed is to favour the growth of the young seedling, whilst struggling with other plants growing vigorously all around. Look at a plant in the midst of its range, why does it not double or quadruple its numbers? We know {78} that it can perfectly well withstand a little more heat or cold, dampness or dryness, for elsewhere it ranges into slightly hotter or colder, damper or drier districts. In this case we can clearly see that if we wished in imagination to give the plant the power of increasing in number, we should have to give it some advantage over its competitors, or over the animals which preyed on it. On the confines of its geographical range, a change of constitution with respect to climate would clearly be an advantage to our plant; but we have reason to believe that only a few plants or animals range so far, that they are destroyed by the rigour of the climate alone. Not until we reach the extreme confines of life, in the Arctic regions or on the borders of an utter desert, will competition cease. The land may be extremely cold or dry, yet there will be competition between some few species, or between the individuals of the same species, for the warmest or dampest spots. Hence, also, we can see that when a plant or animal is placed in a new country amongst new competitors, though the climate may be exactly the same as in its former home, yet the conditions of its life will generally be changed in an essential manner. If we wished to increase its average numbers in its new home, we should have to modify it in a different way to what we should have done in its native country; for we should have to give it some advantage over a different set of competitors or enemies. It is good thus to try in our imagination to give any form some advantage over another. Probably in no single instance should we know what to do, so as to succeed. It will convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary, as it seems to be difficult to acquire. All that we can do, is to keep steadily in mind that each {79} organic being is striving to increase at a geometrical ratio; that each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life, and to suffer great destruction. When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply. * * * * * {80} CHAPTER IV. NATURAL SELECTION. Natural Selection--its power compared with man's selection--its power on characters of trifling importance--its power at all ages and on both sexes--Sexual Selection--On the generality of intercrosses between individuals of the same species--Circumstances favourable and unfavourable to Natural Selection, namely, intercrossing, isolation, number of individuals--Slow action--Extinction caused by Natural Selection--Divergence of Character, related to the diversity of inhabitants of any small area, and to naturalisation--Action of Natural Selection, through Divergence of Character and Extinction, on the descendants from a common parent--Explains the Grouping of all organic beings. How will the struggle for existence, discussed too briefly in the last chapter, act in regard to variation? Can the principle of selection, which we have seen is so potent in the hands of man, apply in nature? I think we shall see that it can act most effectually. Let it be borne in mind in what an endless number of strange peculiarities our domestic productions, and, in a lesser degree, those under nature, vary; and how strong the hereditary tendency is. Under domestication, it may be truly said that the whole organisation becomes in some degree plastic. Let it be borne in mind how infinitely complex and close-fitting are the mutual relations of all organic beings to each other and to their physical conditions of life. Can it, then, be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life, should sometimes occur in the course of thousands of generations? If such do occur, can we doubt {81} (remembering that many more individuals are born than can possibly survive) that individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind? On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed. This preservation of favourable variations and the rejection of injurious variations, I call Natural Selection. Variations neither useful nor injurious would not be affected by natural selection, and would be left a fluctuating element, as perhaps we see in the species called polymorphic. We shall best understand the probable course of natural selection by taking the case of a country undergoing some physical change, for instance, of climate. The proportional numbers of its inhabitants would almost immediately undergo a change, and some species might become extinct. We may conclude, from what we have seen of the intimate and complex manner in which the inhabitants of each country are bound together, that any change in the numerical proportions of some of the inhabitants, independently of the change of climate itself, would seriously affect many of the others. If the country were open on its borders, new forms would certainly immigrate, and this also would seriously disturb the relations of some of the former inhabitants. Let it be remembered how powerful the influence of a single introduced tree or mammal has been shown to be. But in the case of an island, or of a country partly surrounded by barriers, into which new and better adapted forms could not freely enter, we should then have places in the economy of nature which would assuredly be better filled up, if some of the original inhabitants were in some manner modified; for, had the area been open to immigration, these same {82} places would have been seized on by intruders. In such case, every slight modification, which in the course of ages chanced to arise, and which in any way favoured the individuals of any of the species, by better adapting them to their altered conditions, would tend to be preserved; and natural selection would thus have free scope for the work of improvement. We have reason to believe, as stated in the first chapter, that a change in the conditions of life, by specially acting on the reproductive system, causes or increases variability; and in the foregoing case the conditions of life are supposed to have undergone a change, and this would manifestly be favourable to natural selection, by giving a better chance of profitable variations occurring; and unless profitable variations do occur, natural selection can do nothing. Not that, as I believe, any extreme amount of variability is necessary; as man can certainly produce great results by adding up in any given direction mere individual differences, so could Nature, but far more easily, from having incomparably longer time at her disposal. Nor do I believe that any great physical change, as of climate, or any unusual degree of isolation to check immigration, is actually necessary to produce new and unoccupied places for natural selection to fill up by modifying and improving some of the varying inhabitants. For as all the inhabitants of each country are struggling together with nicely balanced forces, extremely slight modifications in the structure or habits of one inhabitant would often give it an advantage over others; and still further modifications of the same kind would often still further increase the advantage. No country can be named in which all the native inhabitants are now so perfectly adapted to each other and to the physical conditions under which they live, that none of {83} them could anyhow be improved; for in all countries, the natives have been so far conquered by naturalised productions, that they have allowed foreigners to take firm possession of the land. And as foreigners have thus everywhere beaten some of the natives, we may safely conclude that the natives might have been modified with advantage, so as to have better resisted such intruders. As man can produce and certainly has produced a great result by his methodical and unconscious means of selection, what may not Nature effect? Man can act only on external and visible characters: Nature cares nothing for appearances, except in so far as they may be useful to any being. She can act on every internal organ, on every shade of constitutional difference, on the whole machinery of life. Man selects only for his own good; Nature only for that of the being which she tends. Every selected character is fully exercised by her; and the being is placed under well-suited conditions of life. Man keeps the natives of many climates in the same country; he seldom exercises each selected character in some peculiar and fitting manner; he feeds a long and a short beaked pigeon on the same food; he does not exercise a long-backed or long-legged quadruped in any peculiar manner; he exposes sheep with long and short wool to the same climate. He does not allow the most vigorous males to struggle for the females. He does not rigidly destroy all inferior animals, but protects during each varying season, as far as lies in his power, all his productions. He often begins his selection by some half-monstrous form; or at least by some modification prominent enough to catch his eye, or to be plainly useful to him. Under nature, the slightest difference of structure or constitution may well turn the nicely-balanced scale in the struggle for life, and so be {84} preserved. How fleeting are the wishes and efforts of man! how short his time! and consequently how poor will his products be, compared with those accumulated by Nature during whole geological periods. Can we wonder, then, that Nature's productions should be far "truer" in character than man's productions; that they should be infinitely better adapted to the most complex conditions of life, and should plainly bear the stamp of far higher workmanship? It may metaphorically be said that natural selection is daily and hourly scrutinising, throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages, and then so imperfect is our view into long past geological ages, that we only see that the forms of life are now different from what they formerly were. Although natural selection can act only through and for the good of each being, yet characters and structures, which we are apt to consider as of very trifling importance, may thus be acted on. When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey; and hawks are guided by eyesight to their prey--so much so, that on {85} parts of the Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. Nor ought we to think that the occasional destruction of an animal of any particular colour would produce little effect: we should remember how essential it is in a flock of white sheep to destroy every lamb with the faintest trace of black. In plants the down on the fruit and the colour of the flesh are considered by botanists as characters of the most trifling importance: yet we hear from an excellent horticulturist, Downing, that in the United States smooth-skinned fruits suffer far more from a beetle, a curculio, than those with down; that purple plums suffer far more from a certain disease than yellow plums; whereas another disease attacks yellow-fleshed peaches far more than those with other coloured flesh. If, with all the aids of art, these slight differences make a great difference in cultivating the several varieties, assuredly, in a state of nature, where the trees would have to struggle with other trees and with a host of enemies, such differences would effectually settle which variety, whether a smooth or downy, a yellow or purple fleshed fruit, should succeed. In looking at many small points of difference between species, which, as far as our ignorance permits us to judge, seem quite unimportant, we must not forget that climate, food, &c., probably produce some slight and direct effect. It is, however, far more necessary to bear in mind that there are many unknown laws of correlation of growth, which, when one part of the organisation is modified through variation, and the modifications are accumulated by natural selection for {86} the good of the being, will cause other modifications, often of the most unexpected nature. As we see that those variations which under domestication appear at any particular period of life, tend to reappear in the offspring at the same period;--for instance, in the seeds of the many varieties of our culinary and agricultural plants; in the caterpillar and cocoon stages of the varieties of the silkworm; in the eggs of poultry, and in the colour of the down of their chickens; in the horns of our sheep and cattle when nearly adult;--so in a state of nature, natural selection will be enabled to act on and modify organic beings at any age, by the accumulation of variations profitable at that age, and by their inheritance at a corresponding age. If it profit a plant to have its seeds more and more widely disseminated by the wind, I can see no greater difficulty in this being effected through natural selection, than in the cotton-planter increasing and improving by selection the down in the pods on his cotton-trees. Natural selection may modify and adapt the larva of an insect to a score of contingencies, wholly different from those which concern the mature insect. These modifications will no doubt affect, through the laws of correlation, the structure of the adult; and probably in the case of those insects which live only for a few hours, and which never feed, a large part of their structure is merely the correlated result of successive changes in the structure of their larvæ. So, conversely, modifications in the adult will probably often affect the structure of the larva; but in all cases natural selection will ensure that modifications consequent on other modifications at a different period of life, shall not be in the least degree injurious: for if they became so, they would cause the extinction of the species. Natural selection will modify the structure of the {87} young in relation to the parent, and of the parent in relation to the young. In social animals it will adapt the structure of each individual for the benefit of the community; if each in consequence profits by the selected change. What natural selection cannot do, is to modify the structure of one species, without giving it any advantage, for the good of another species; and though statements to this effect may be found in works of natural history, I cannot find one case which will bear investigation. A structure used only once in an animal's whole life, if of high importance to it, might be modified to any extent by natural selection; for instance, the great jaws possessed by certain insects, used exclusively for opening the cocoon--or the hard tip to the beak of nestling birds, used for breaking the egg. It has been asserted, that of the best short-beaked tumbler-pigeons more perish in the egg than are able to get out of it; so that fanciers assist in the act of hatching. Now, if nature had to make the beak of a full-grown pigeon very short for the bird's own advantage, the process of modification would be very slow, and there would be simultaneously the most rigorous selection of the young birds within the egg, which had the most powerful and hardest beaks, for all with weak beaks would inevitably perish: or, more delicate and more easily broken shells might be selected, the thickness of the shell being known to vary like every other structure. _Sexual Selection._--Inasmuch as peculiarities often appear under domestication in one sex and become hereditarily attached to that sex, the same fact probably occurs under nature, and if so, natural selection will be able to modify one sex in its functional relations to the other sex, or in relation to wholly different habits of life in the two sexes, as is sometimes the case {88} with insects. And this leads me to say a few words on what I call Sexual Selection. This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases, victory depends not on general vigour, but on having special weapons, confined to the male sex. A hornless stag or spurless cock would have a poor chance of leaving offspring. Sexual selection by always allowing the victor to breed might surely give indomitable courage, length to the spur, and strength to the wing to strike in the spurred leg, as well as the brutal cock-fighter, who knows well that he can improve his breed by careful selection of the best cocks. How low in the scale of nature the law of battle descends, I know not; male alligators have been described as fighting, bellowing, and whirling round, like Indians in a war-dance, for the possession of the females; male salmons have been seen fighting all day long; male stag-beetles often bear wounds from the huge mandibles of other males. The war is, perhaps, severest between the males of polygamous animals, and these seem oftenest provided with special weapons. The males of carnivorous animals are already well armed; though to them and to others, special means of defence may be given through means of sexual selection, as the mane to the lion, the shoulder-pad to the boar, and the hooked jaw to the male salmon; for the shield may be as important for victory, as the sword or spear. Amongst birds, the contest is often of a more peaceful character. All those who have attended to the subject, {89} believe that there is the severest rivalry between the males of many species to attract by singing the females. The rock-thrush of Guiana, birds of Paradise, and some others, congregate; and successive males display their gorgeous plumage and perform strange antics before the females, which, standing by as spectators, at last choose the most attractive partner. Those who have closely attended to birds in confinement well know that they often take individual preferences and dislikes: thus Sir R. Heron has described how one pied peacock was eminently attractive to all his hen birds. It may appear childish to attribute any effect to such apparently weak means: I cannot here enter on the details necessary to support this view; but if man can in a short time give elegant carriage and beauty to his bantams, according to his standard of beauty, I can see no good reason to doubt that female birds, by selecting, during thousands of generations, the most melodious or beautiful males, according to their standard of beauty, might produce a marked effect. I strongly suspect that some well-known laws, with respect to the plumage of male and female birds, in comparison with the plumage of the young, can be explained on the view of plumage having been chiefly modified by sexual selection, acting when the birds have come to the breeding age or during the breeding season; the modifications thus produced being inherited at corresponding ages or seasons, either by the males alone, or by the males and females; but I have not space here to enter on this subject. Thus it is, as I believe, that when the males and females of any animal have the same general habits of life, but differ in structure, colour, or ornament, such differences have been mainly caused by sexual selection; that is, individual males have had, in successive generations, some slight advantage over other {90} males, in their weapons, means of defence, or charms; and have transmitted these advantages to their male offspring. Yet, I would not wish to attribute all such sexual differences to this agency: for we see peculiarities arising and becoming attached to the male sex in our domestic animals (as the wattle in male carriers, horn-like protuberances in the cocks of certain fowls, &c.), which we cannot believe to be either useful to the males in battle, or attractive to the females. We see analogous cases under nature, for instance, the tuft of hair on the breast of the turkey-cock, which can hardly be either useful or ornamental to this bird;--indeed, had the tuft appeared under domestication, it would have been called a monstrosity. _Illustrations of the action of Natural Selection._--In order to make it clear how, as I believe, natural selection acts, I must beg permission to give one or two imaginary illustrations. Let us take the case of a wolf, which preys on various animals, securing some by craft, some by strength, and some by fleetness; and let us suppose that the fleetest prey, a deer for instance, had from any change in the country increased in numbers, or that other prey had decreased in numbers, during that season of the year when the wolf is hardest pressed for food. I can under such circumstances see no reason to doubt that the swiftest and slimmest wolves would have the best chance of surviving, and so be preserved or selected,--provided always that they retained strength to master their prey at this or at some other period of the year, when they might be compelled to prey on other animals. I can see no more reason to doubt this, than that man can improve the fleetness of his greyhounds by careful and methodical selection, or by that unconscious selection which results from each man trying {91} to keep the best dogs without any thought of modifying the breed. Even without any change in the proportional numbers of the animals on which our wolf preyed, a cub might be born with an innate tendency to pursue certain kinds of prey. Nor can this be thought very improbable; for we often observe great differences in the natural tendencies of our domestic animals; one cat, for instance, taking to catch rats, another mice; one cat, according to Mr. St. John, bringing home winged game, another hares or rabbits, and another hunting on marshy ground and almost nightly catching woodcocks or snipes. The tendency to catch rats rather than mice is known to be inherited. Now, if any slight innate change of habit or of structure benefited an individual wolf, it would have the best chance of surviving and of leaving offspring. Some of its young would probably inherit the same habits or structure, and by the repetition of this process, a new variety might be formed which would either supplant or coexist with the parent form of wolf. Or, again, the wolves inhabiting a mountainous district, and those frequenting the lowlands, would naturally be forced to hunt different prey; and from the continued preservation of the individuals best fitted for the two sites, two varieties might slowly be formed. These varieties would cross and blend where they met; but to this subject of intercrossing we shall soon have to return. I may add, that, according to Mr. Pierce, there are two varieties of the wolf inhabiting the Catskill Mountains in the United States, one with a light greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which more frequently attacks the shepherd's flocks. Let us now take a more complex case. Certain plants excrete a sweet juice, apparently for the sake of eliminating something injurious from their sap: this is {92} effected by glands at the base of the stipules in some Leguminosæ, and at the back of the leaf of the common laurel. This juice, though small in quantity, is greedily sought by insects. Let us now suppose a little sweet juice or nectar to be excreted by the inner bases of the petals of a flower. In this case insects in seeking the nectar would get dusted with pollen, and would certainly often transport the pollen from one flower to the stigma of another flower. The flowers of two distinct individuals of the same species would thus get crossed; and the act of crossing, we have good reason to believe (as will hereafter be more fully alluded to), would produce very vigorous seedlings, which consequently would have the best chance of flourishing and surviving. Some of these seedlings would probably inherit the nectar-excreting power. Those individual flowers which had the largest glands or nectaries, and which excreted most nectar, would be oftenest visited by insects, and would be oftenest crossed; and so in the long-run would gain the upper hand. Those flowers, also, which had their stamens and pistils placed, in relation to the size and habits of the particular insects which visited them, so as to favour in any degree the transportal of their pollen from flower to flower, would likewise be favoured or selected. We might have taken the case of insects visiting flowers for the sake of collecting pollen instead of nectar; and as pollen is formed for the sole object of fertilisation, its destruction appears a simple loss to the plant; yet if a little pollen were carried, at first occasionally and then habitually, by the pollen-devouring insects from flower to flower, and a cross thus effected, although nine-tenths of the pollen were destroyed, it might still be a great gain to the plant; and those individuals which produced more and more pollen, and had larger and larger anthers, would be selected. {93} When our plant, by this process of the continued preservation or natural selection of more and more attractive flowers, had been rendered highly attractive to insects, they would, unintentionally on their part, regularly carry pollen from flower to flower; and that they can most effectually do this, I could easily show by many striking instances. I will give only one--not as a very striking case, but as likewise illustrating one step in the separation of the sexes of plants, presently to be alluded to. Some holly-trees bear only male flowers, which have four stamens producing a rather small quantity of pollen, and a rudimentary pistil; other holly-trees bear only female flowers; these have a full-sized pistil, and four stamens with shrivelled anthers, in which not a grain of pollen can be detected. Having found a female tree exactly sixty yards from a male tree, I put the stigmas of twenty flowers, taken from different branches, under the microscope, and on all, without exception, there were pollen-grains, and on some a profusion of pollen. As the wind had set for several days from the female to the male tree, the pollen could not thus have been carried. The weather had been cold and boisterous, and therefore not favourable to bees, nevertheless every female flower which I examined had been effectually fertilised by the bees, accidentally dusted with pollen, having flown from tree to tree in search of nectar. But to return to our imaginary case: as soon as the plant had been rendered so highly attractive to insects that pollen was regularly carried from flower to flower, another process might commence. No naturalist doubts the advantage of what has been called the "physiological division of labour;" hence we may believe that it would be advantageous to a plant to produce stamens alone in one flower or on one whole plant, and pistils alone in {94} another flower or on another plant. In plants under culture and placed under new conditions of life, sometimes the male organs and sometimes the female organs become more or less impotent; now if we suppose this to occur in ever so slight a degree under nature, then as pollen is already carried regularly from flower to flower, and as a more complete separation of the sexes of our plant would be advantageous on the principle of the division of labour, individuals with this tendency more and more increased, would be continually favoured or selected, until at last a complete separation of the sexes would be effected. Let us now turn to the nectar-feeding insects in our imaginary case: we may suppose the plant of which we have been slowly increasing the nectar by continued selection, to be a common plant; and that certain insects depended in main part on its nectar for food. I could give many facts, showing how anxious bees are to save time; for instance, their habit of cutting holes and sucking the nectar at the bases of certain flowers, which they can, with a very little more trouble, enter by the mouth. Bearing such facts in mind, I can see no reason to doubt that an accidental deviation in the size and form of the body, or in the curvature and length of the proboscis, &c., far too slight to be appreciated by us, might profit a bee or other insect, so that an individual so characterised would be able to obtain its food more quickly, and so have a better chance of living and leaving descendants. Its descendants would probably inherit a tendency to a similar slight deviation of structure. The tubes of the corollas of the common red and incarnate clovers (Trifolium pratense and incarnatum) do not on a hasty glance appear to differ in length; yet the hive-bee can easily suck the nectar out of the incarnate clover, but not out of the common red {95} clover, which is visited by humble-bees alone; so that whole fields of the red clover offer in vain an abundant supply of precious nectar to the hive-bee. Thus it might be a great advantage to the hive-bee to have a slightly longer or differently constructed proboscis. On the other hand, I have found by experiment that the fertility of clover depends on bees visiting and moving parts of the corolla, so as to push the pollen on to the stigmatic surface. Hence, again, if humble-bees were to become rare in any country, it might be a great advantage to the red clover to have a shorter or more deeply divided tube to its corolla, so that the hive-bee could visit its flowers. Thus I can understand how a flower and a bee might slowly become, either simultaneously or one after the other, modified and adapted in the most perfect manner to each other, by the continued preservation of individuals presenting mutual and slightly favourable deviations of structure. I am well aware that this doctrine of natural selection, exemplified in the above imaginary instances, is open to the same objections which were at first urged against Sir Charles Lyell's noble views on "the modern changes of the earth, as illustrative of geology;" but we now seldom hear the action, for instance, of the coast-waves, called a trifling and insignificant cause, when applied to the excavation of gigantic valleys or to the formation of the longest lines of inland cliffs. Natural selection can act only by the preservation and accumulation of infinitesimally small inherited modifications, each profitable to the preserved being; and as modern geology has almost banished such views as the excavation of a great valley by a single diluvial wave, so will natural selection, if it be a true principle, banish the belief of the continued creation of new organic {96} beings, or of any great and sudden modification in their structure. _On the Intercrossing of Individuals._--I must here introduce a short digression. In the case of animals and plants with separated sexes, it is of course obvious that two individuals must always (with the exception of the curious and not well-understood cases of parthenogenesis) unite for each birth; but in the case of hermaphrodites this is far from obvious. Nevertheless I am strongly inclined to believe that with all hermaphrodites two individuals, either occasionally or habitually, concur for the reproduction of their kind. This view was first suggested by Andrew Knight. We shall presently see its importance; but I must here treat the subject with extreme brevity, though I have the materials prepared for an ample discussion. All vertebrate animals, all insects, and some other large groups of animals, pair for each birth. Modern research has much diminished the number of supposed hermaphrodites, and of real hermaphrodites a large number pair; that is, two individuals regularly unite for reproduction, which is all that concerns us. But still there are many hermaphrodite animals which certainly do not habitually pair, and a vast majority of plants are hermaphrodites. What reason, it may be asked, is there for supposing in these cases that two individuals ever concur in reproduction? As it is impossible here to enter on details, I must trust to some general considerations alone. In the first place, I have collected so large a body of facts, showing, in accordance with the almost universal belief of breeders, that with animals and plants a cross between different varieties, or between individuals of the same variety but of another strain, gives vigour and {97} fertility to the offspring; and on the other hand, that _close_ interbreeding diminishes vigour and fertility; that these facts alone incline me to believe that it is a general law of nature (utterly ignorant though we be of the meaning of the law) that no organic being self-fertilises itself for an eternity of generations; but that a cross with another individual is occasionally--perhaps at very long intervals--indispensable. On the belief that this is a law of nature, we can, I think, understand several large classes of facts, such as the following, which on any other view are inexplicable. Every hybridizer knows how unfavourable exposure to wet is to the fertilisation of a flower, yet what a multitude of flowers have their anthers and stigmas fully exposed to the weather! but if an occasional cross be indispensable, the fullest freedom for the entrance of pollen from another individual will explain this state of exposure, more especially as the plant's own anthers and pistil generally stand so close together that self-fertilisation seems almost inevitable. Many flowers, on the other hand, have their organs of fructification closely enclosed, as in the great papilionaceous or pea-family; but in several, perhaps in all, such flowers, there is a very curious adaptation between the structure of the flower and the manner in which bees suck the nectar; for, in doing this, they either push the flower's own pollen on the stigma, or bring pollen from another flower. So necessary are the visits of bees to papilionaceous flowers, that I have found, by experiments published elsewhere, that their fertility is greatly diminished if these visits be prevented. Now, it is scarcely possible that bees should fly from flower to flower, and not carry pollen from one to the other, to the great good, as I believe, of the plant. Bees will act like a camel-hair pencil, and it is quite sufficient just to touch the anthers of {98} one flower and then the stigma of another with the same brush to ensure fertilisation; but it must not be supposed that bees would thus produce a multitude of hybrids between distinct species; for if you bring on the same brush a plant's own pollen and pollen from another species, the former will have such a prepotent effect, that it will invariably and completely destroy, as has been shown by Gärtner, any influence from the foreign pollen. When the stamens of a flower suddenly spring towards the pistil, or slowly move one after the other towards it, the contrivance seems adapted solely to ensure self-fertilisation; and no doubt it is useful for this end: but, the agency of insects is often required to cause the stamens to spring forward, as Kölreuter has shown to be the case with the barberry; and in this very genus, which seems to have a special contrivance for self-fertilisation, it is well known that if closely-allied forms or varieties are planted near each other, it is hardly possible to raise pure seedlings, so largely do they naturally cross. In many other cases, far from there being any aids for self-fertilisation, there are special contrivances, as I could show from the writings of C. C. Sprengel and from my own observations, which effectually prevent the stigma receiving pollen from its own flower: for instance, in Lobelia fulgens, there is a really beautiful and elaborate contrivance by which every one of the infinitely numerous pollen-granules are swept out of the conjoined anthers of each flower, before the stigma of that individual flower is ready to receive them; and as this flower is never visited, at least in my garden, by insects, it never sets a seed, though by placing pollen from one flower on the stigma of another, I raised plenty of seedlings; and whilst another species of Lobelia growing close by, which is visited by bees, seeds freely. In very many other cases, though there {99} be no special mechanical contrivance to prevent the stigma of a flower receiving its own pollen, yet, as C. C. Sprengel has shown, and as I can confirm, either the anthers burst before the stigma is ready for fertilisation, or the stigma is ready before the pollen of that flower is ready, so that these plants have in fact separated sexes, and must habitually be crossed. How strange are these facts! How strange that the pollen and stigmatic surface of the same flower, though placed so close together, as if for the very purpose of self-fertilisation, should in so many cases be mutually useless to each other! How simply are these facts explained on the view of an occasional cross with a distinct individual being advantageous or indispensable! If several varieties of the cabbage, radish, onion, and of some other plants, be allowed to seed near each other, a large majority, as I have found, of the seedlings thus raised will turn out mongrels: for instance, I raised 233 seedling cabbages from some plants of different varieties growing near each other, and of these only 78 were true to their kind, and some even of these were not perfectly true. Yet the pistil of each cabbage-flower is surrounded not only by its own six stamens, but by those of the many other flowers on the same plant. How, then, comes it that such a vast number of the seedlings are mongrelized? I suspect that it must arise from the pollen of a distinct _variety_ having a prepotent effect over a flower's own pollen; and that this is part of the general law of good being derived from the intercrossing of distinct individuals of the same species. When distinct _species_ are crossed the case is directly the reverse, for a plant's own pollen is always prepotent over foreign pollen; but to this subject we shall return in a future chapter. In the case of a gigantic tree covered with {100} innumerable flowers, it may be objected that pollen could seldom be carried from tree to tree, and at most only from flower to flower on the same tree, and that flowers on the same tree can be considered as distinct individuals only in a limited sense. I believe this objection to be valid, but that nature has largely provided against it by giving to trees a strong tendency to bear flowers with separated sexes. When the sexes are separated, although the male and female flowers may be produced on the same tree, we can see that pollen must be regularly carried from flower to flower; and this will give a better chance of pollen being occasionally carried from tree to tree. That trees belonging to all Orders have their sexes more often separated than other plants, I find to be the case in this country; and at my request Dr. Hooker tabulated the trees of New Zealand, and Dr. Asa Gray those of the United States, and the result was as I anticipated. On the other hand, Dr. Hooker has recently informed me that he finds that the rule does not hold in Australia; and I have made these few remarks on the sexes of trees simply to call attention to the subject. Turning for a very brief space to animals: on the land there are some hermaphrodites, as land-mollusca and earth-worms; but these all pair. As yet I have not found a single case of a terrestrial animal which fertilises itself. We can understand this remarkable fact, which offers so strong a contrast with terrestrial plants, on the view of an occasional cross being indispensable, by considering the medium in which terrestrial animals live, and the nature of the fertilising element; for we know of no means, analogous to the action of insects and of the wind in the case of plants, by which an occasional cross could be effected with terrestrial animals without the concurrence of two individuals. Of aquatic animals, there are many self-fertilising hermaphrodites; but here {101} currents in the water offer an obvious means for an occasional cross. And, as in the case of flowers, I have as yet failed, after consultation with one of the highest authorities, namely, Professor Huxley, to discover a single case of an hermaphrodite animal with the organs of reproduction so perfectly enclosed within the body, that access from without and the occasional influence of a distinct individual can be shown to be physically impossible. Cirripedes long appeared to me to present a case of very great difficulty under this point of view; but I have been enabled, by a fortunate chance, elsewhere to prove that two individuals, though both are self-fertilising hermaphrodites, do sometimes cross. It must have struck most naturalists as a strange anomaly that, in the case of both animals and plants, species of the same family and even of the same genus, though agreeing closely with each other in almost their whole organisation, yet are not rarely, some of them hermaphrodites, and some of them unisexual. But if, in fact, all hermaphrodites do occasionally intercross with other individuals, the difference between hermaphrodites and unisexual species, as far as function is concerned, becomes very small. From these several considerations and from the many special facts which I have collected, but which I am not here able to give, I am strongly inclined to suspect that, both in the vegetable and animal kingdoms, an occasional intercross with a distinct individual is a law of nature. I am well aware that there are, on this view, many cases of difficulty, some of which I am trying to investigate. Finally then, we may conclude that in many organic beings, a cross between two individuals is an obvious necessity for each birth; in many others it occurs perhaps only at long intervals; but in none, as I suspect, can self-fertilisation go on for perpetuity. {102} _Circumstances favourable to Natural Selection._--This is an extremely intricate subject. A large amount of inheritable and diversified variability is favourable, but I believe mere individual differences suffice for the work. A large number of individuals, by giving a better chance for the appearance within any given period of profitable variations, will compensate for a lesser amount of variability in each individual, and is, I believe, an extremely important element of success. Though nature grants vast periods of time for the work of natural selection, she does not grant an indefinite period; for as all organic beings are striving, it may be said, to seize on each place in the economy of nature, if any one species does not become modified and improved in a corresponding degree with its competitors, it will soon be exterminated. In man's methodical selection, a breeder selects for some definite object, and free intercrossing will wholly stop his work. But when many men, without intending to alter the breed, have a nearly common standard of perfection, and all try to get and breed from the best animals, much improvement and modification surely but slowly follow from this unconscious process of selection, notwithstanding a large amount of crossing with inferior animals. Thus it will be in nature; for within a confined area, with some place in its polity not so perfectly occupied as might be, natural selection will always tend to preserve all the individuals varying in the right direction, though in different degrees, so as better to fill up the unoccupied place. But if the area be large, its several districts will almost certainly present different conditions of life; and then if natural selection be modifying and improving a species in the several districts, there will be intercrossing with the other individuals of the same species on the confines of each. And in {103} this case the effects of intercrossing can hardly be counterbalanced by natural selection always tending to modify all the individuals in each district in exactly the same manner to the conditions of each; for in a continuous area, the physical conditions at least will generally graduate away insensibly from one district to another. The intercrossing will most affect those animals which unite for each birth, which wander much, and which do not breed at a very quick rate. Hence in animals of this nature, for instance in birds, varieties will generally be confined to separated countries; and this I believe to be the case. In hermaphrodite organisms which cross only occasionally, and likewise in animals which unite for each birth, but which wander little and which can increase at a very rapid rate, a new and improved variety might be quickly formed on any one spot, and might there maintain itself in a body, so that whatever intercrossing took place would be chiefly between the individuals of the same new variety. A local variety when once thus formed might subsequently slowly spread to other districts. On the above principle, nurserymen always prefer getting seed from a large body of plants of the same variety, as the chance of intercrossing with other varieties is thus lessened. Even in the case of slow-breeding animals, which unite for each birth, we must not overrate the effects of intercrosses in retarding natural selection; for I can bring a considerable catalogue of facts, showing that within the same area, varieties of the same animal can long remain distinct, from haunting different stations, from breeding at slightly different seasons, or from varieties of the same kind preferring to pair together. Intercrossing plays a very important part in nature in keeping the individuals of the same species, or of the same variety, true and uniform in character. It will {104} obviously thus act far more efficiently with those animals which unite for each birth; but I have already attempted to show that we have reason to believe that occasional intercrosses take place with all animals and with all plants. Even if these take place only at long intervals, I am convinced that the young thus produced will gain so much in vigour and fertility over the offspring from long-continued self-fertilisation, that they will have a better chance of surviving and propagating their kind; and thus, in the long run, the influence of intercrosses, even at rare intervals, will be great. If there exist organic beings which never intercross, uniformity of character can be retained amongst them, as long as their conditions of life remain the same, only through the principle of inheritance, and through natural selection destroying any which depart from the proper type; but if their conditions of life change and they undergo modification, uniformity of character can be given to their modified offspring, solely by natural selection preserving the same favourable variations. Isolation, also, is an important element in the process of natural selection. In a confined or isolated area, if not very large, the organic and inorganic conditions of life will generally be in a great degree uniform; so that natural selection will tend to modify all the individuals of a varying species throughout the area in the same manner in relation to the same conditions. Intercrosses, also, with the individuals of the same species, which otherwise would have inhabited the surrounding and differently circumstanced districts, will be prevented. But isolation probably acts more efficiently in checking the immigration of better adapted organisms, after any physical change, such as of climate or elevation of the land, &c.; and thus new places in the natural economy of the country are left open for the old inhabitants to struggle for, and become adapted to, through {105} modifications in their structure and constitution. Lastly, isolation, by checking immigration and consequently competition, will give time for any new variety to be slowly improved; and this may sometimes be of importance in the production of new species. If, however, an isolated area be very small, either from being surrounded by barriers, or from having very peculiar physical conditions, the total number of the individuals supported on it will necessarily be very small; and fewness of individuals will greatly retard the production of new species through natural selection, by decreasing the chance of the appearance of favourable variations. If we turn to nature to test the truth of these remarks, and look at any small isolated area, such as an oceanic island, although the total number of the species inhabiting it, will be found to be small, as we shall see in our chapter on geographical distribution; yet of these species a very large proportion are endemic,--that is, have been produced there, and nowhere else. Hence an oceanic island at first sight seems to have been highly favourable for the production of new species. But we may thus greatly deceive ourselves, for to ascertain whether a small isolated area, or a large open area like a continent, has been most favourable for the production of new organic forms, we ought to make the comparison within equal times; and this we are incapable of doing. Although I do not doubt that isolation is of considerable importance in the production of new species, on the whole I am inclined to believe that largeness of area is of more importance, more especially in the production of species, which will prove capable of enduring for a long period, and of spreading widely. Throughout a great and open area, not only will there be a better chance of favourable variations arising from the large number of individuals of the same species {106} there supported, but the conditions of life are infinitely complex from the large number of already existing species; and if some of these many species become modified and improved, others will have to be improved in a corresponding degree or they will be exterminated. Each new form, also, as soon as it has been much improved, will be able to spread over the open and continuous area, and will thus come into competition with many others. Hence more new places will be formed, and the competition to fill them will be more severe, on a large than on a small and isolated area. Moreover, great areas, though now continuous, owing to oscillations of level, will often have recently existed in a broken condition, so that the good effects of isolation will generally, to a certain extent, have concurred. Finally, I conclude that, although small isolated areas probably have been in some respects highly favourable for the production of new species, yet that the course of modification will generally have been more rapid on large areas; and what is more important, that the new forms produced on large areas, which already have been victorious over many competitors, will be those that will spread most widely, will give rise to most new varieties and species, and will thus play an important part in the changing history of the organic world. We can, perhaps, on these views, understand some facts which will be again alluded to in our chapter on geographical distribution; for instance, that the productions of the smaller continent of Australia have formerly yielded, and apparently are now yielding, before those of the larger Europæo-Asiatic area. Thus, also, it is that continental productions have everywhere become so largely naturalised on islands. On a small island, the race for life will have been less severe, and there will have been less modification and less {107} extermination. Hence, perhaps, it comes that the flora of Madeira, according to Oswald Heer, resembles the extinct tertiary flora of Europe. All fresh-water basins, taken together, make a small area compared with that of the sea or of the land; and, consequently, the competition between fresh-water productions will have been less severe than elsewhere; new forms will have been more slowly formed, and old forms more slowly exterminated. And it is in fresh water that we find seven genera of Ganoid fishes, remnants of a once preponderant order: and in fresh water we find some of the most anomalous forms now known in the world, as the Ornithorhynchus and Lepidosiren, which, like fossils, connect to a certain extent orders now widely separated in the natural scale. These anomalous forms may almost be called living fossils; they have endured to the present day, from having inhabited a confined area, and from having thus been exposed to less severe competition. To sum up the circumstances favourable and unfavourable to natural selection, as far as the extreme intricacy of the subject permits. I conclude, looking to the future, that for terrestrial productions a large continental area, which will probably undergo many oscillations of level, and which consequently will exist for long periods in a broken condition, is the most favourable for the production of many new forms of life, likely to endure long and to spread widely. For the area first existed as a continent, and the inhabitants, at this period numerous in individuals and kinds, will have been subjected to very severe competition. When converted by subsidence into large separate islands, there will still exist many individuals of the same species on each island: intercrossing on the confines of the range of each species will thus be checked: after physical changes of any kind, immigration will be {108} prevented, so that new places in the polity of each island will have to be filled up by modifications of the old inhabitants; and time will be allowed for the varieties in each to become well modified and perfected. When, by renewed elevation, the islands shall be re-converted into a continental area, there will again be severe competition: the most favoured or improved varieties will be enabled to spread: there will be much extinction of the less improved forms, and the relative proportional numbers of the various inhabitants of the renewed continent will again be changed; and again there will be a fair field for natural selection to improve still further the inhabitants, and thus produce new species. That natural selection will always act with extreme slowness, I fully admit. Its action depends on there being places in the polity of nature, which can be better occupied by some of the inhabitants of the country undergoing modification of some kind. The existence of such places will often depend on physical changes, which are generally very slow, and on the immigration of better adapted forms having been checked. But the action of natural selection will probably still oftener depend on some of the inhabitants becoming slowly modified; the mutual relations of many of the other inhabitants being thus disturbed. Nothing can be effected, unless favourable variations occur, and variation itself is apparently always a very slow process. The process will often be greatly retarded by free intercrossing. Many will exclaim that these several causes are amply sufficient wholly to stop the action of natural selection. I do not believe so. On the other hand, I do believe that natural selection always acts very slowly, often only at long intervals of time, and generally on only a very few of the inhabitants of the same region at the same time. I further believe, that this very slow, {109} intermittent action of natural selection accords perfectly well with what geology tells us of the rate and manner at which the inhabitants of this world have changed. Slow though the process of selection may be, if feeble man can do much by his powers of artificial selection, I can see no limit to the amount of change, to the beauty and infinite complexity of the coadaptations between all organic beings, one with another and with their physical conditions of life, which may be effected in the long course of time by nature's power of selection. _Extinction._--This subject will be more fully discussed in our chapter on Geology; but it must be here alluded to from being intimately connected with natural selection. Natural selection acts solely through the preservation of variations in some way advantageous, which consequently endure. But as from the high geometrical ratio of increase of all organic beings, each area is already fully stocked with inhabitants, it follows that as each selected and favoured form increases in number, so will the less favoured forms decrease and become rare. Rarity, as geology tells us, is the precursor to extinction. We can, also, see that any form represented by few individuals will, during fluctuations in the seasons or in the number of its enemies, run a good chance of utter extinction. But we may go further than this; for as new forms are continually and slowly being produced, unless we believe that the number of specific forms goes on perpetually and almost indefinitely increasing, numbers inevitably must become extinct. That the number of specific forms has not indefinitely increased, geology shows us plainly; and indeed we can see reason why they should not have thus increased, for the number of places in the polity of nature is not indefinitely great,--not that we {110} have any means of knowing that any one region has as yet got its maximum of species. Probably no region is as yet fully stocked, for at the Cape of Good Hope, where more species of plants are crowded together than in any other quarter of the world, some foreign plants have become naturalised, without causing, as far as we know, the extinction of any natives. Furthermore, the species which are most numerous in individuals will have the best chance of producing within any given period favourable variations. We have evidence of this, in the facts given in the second chapter, showing that it is the common species which afford the greatest number of recorded varieties, or incipient species. Hence, rare species will be less quickly modified or improved within any given period, and they will consequently be beaten in the race for life by the modified descendants of the commoner species. From these several considerations I think it inevitably follows, that as new species in the course of time are formed through natural selection, others will become rarer and rarer, and finally extinct. The forms which stand in closest competition with those undergoing modification and improvement, will naturally suffer most. And we have seen in the chapter on the Struggle for Existence that it is the most closely-allied forms,--varieties of the same species, and species of the same genus or of related genera,--which, from having nearly the same structure, constitution, and habits, generally come into the severest competition with each other. Consequently, each new variety or species, during the progress of its formation, will generally press hardest on its nearest kindred, and tend to exterminate them. We see the same process of extermination amongst our domesticated productions, through the selection of improved forms by man. Many curious {111} instances could be given showing how quickly new breeds of cattle, sheep, and other animals, and varieties of flowers, take the place of older and inferior kinds. In Yorkshire, it is historically known that the ancient black cattle were displaced by the long-horns, and that these "were swept away by the short-horns" (I quote the words of an agricultural writer) "as if by some murderous pestilence." _Divergence of Character._--The principle, which I have designated by this term, is of high importance on my theory, and explains, as I believe, several important facts. In the first place, varieties, even strongly-marked ones, though having somewhat of the character of species--as is shown by the hopeless doubts in many cases how to rank them--yet certainly differ from each other far less than do good and distinct species. Nevertheless, according to my view, varieties are species in the process of formation, or are, as I have called them, incipient species. How, then, does the lesser difference between varieties become augmented into the greater difference between species? That this does habitually happen, we must infer from most of the innumerable species throughout nature presenting well-marked differences; whereas varieties, the supposed prototypes and parents of future well-marked species, present slight and ill-defined differences. Mere chance, as we may call it, might cause one variety to differ in some character from its parents, and the offspring of this variety again to differ from its parent in the very same character and in a greater degree; but this alone would never account for so habitual and large an amount of difference as that between varieties of the same species and species of the same genus. As has always been my practice, let us seek light on {112} this head from our domestic productions. We shall here find something analogous. A fancier is struck by a pigeon having a slightly shorter beak; another fancier is struck by a pigeon having a rather longer beak; and on the acknowledged principle that "fanciers do not and will not admire a medium standard, but like extremes," they both go on (as has actually occurred with tumbler-pigeons) choosing and breeding from birds with longer and longer beaks, or with shorter and shorter beaks. Again, we may suppose that at an early period one man preferred swifter horses; another stronger and more bulky horses. The early differences would be very slight; in the course of time, from the continued selection of swifter horses by some breeders, and of stronger ones by others, the differences would become greater, and would be noted as forming two sub-breeds; finally, after the lapse of centuries, the sub-breeds would become converted into two well-established and distinct breeds. As the differences slowly become greater, the inferior animals with intermediate characters, being neither very swift nor very strong, will have been neglected, and will have tended to disappear. Here, then, we see in man's productions the action of what may be called the principle of divergence, causing differences, at first barely appreciable, steadily to increase, and the breeds to diverge in character both from each other and from their common parent. But how, it may be asked, can any analogous principle apply in nature? I believe it can and does apply most efficiently, from the simple circumstance that the more diversified the descendants from any one species become in structure, constitution, and habits, by so much will they be better enabled to seize on many and widely diversified places in the polity of nature, and so be enabled to increase in numbers. {113} We can clearly see this in the case of animals with simple habits. Take the case of a carnivorous quadruped, of which the number that can be supported in any country has long ago arrived at its full average. If its natural powers of increase be allowed to act, it can succeed in increasing (the country not undergoing any change in its conditions) only by its varying descendants seizing on places at present occupied by other animals: some of them, for instance, being enabled to feed on new kinds of prey, either dead or alive; some inhabiting new stations, climbing trees, frequenting water, and some perhaps becoming less carnivorous. The more diversified in habits and structure the descendants of our carnivorous animal became, the more places they would be enabled to occupy. What applies to one animal will apply throughout all time to all animals--that is, if they vary--for otherwise natural selection can do nothing. So it will be with plants. It has been experimentally proved, that if a plot of ground be sown with one species of grass, and a similar plot be sown with several distinct genera of grasses, a greater number of plants and a greater weight of dry herbage can thus be raised. The same has been found to hold good when first one variety and then several mixed varieties of wheat have been sown on equal spaces of ground. Hence, if any one species of grass were to go on varying, and those varieties were continually selected which differed from each other in at all the same manner as distinct species and genera of grasses differ from each other, a greater number of individual plants of this species of grass, including its modified descendants, would succeed in living on the same piece of ground. And we well know that each species and each variety of grass is annually sowing almost countless seeds; and thus, as it may be said, is striving its utmost to increase its numbers. {114} Consequently, I cannot doubt that in the course of many thousands of generations, the most distinct varieties of any one species of grass would always have the best chance of succeeding and of increasing in numbers, and thus of supplanting the less distinct varieties; and varieties, when rendered very distinct from each other, take the rank of species. The truth of the principle, that the greatest amount of life can be supported by great diversification of structure, is seen under many natural circumstances. In an extremely small area, especially if freely open to immigration, and where the contest between individual and individual must be severe, we always find great diversity in its inhabitants. For instance, I found that a piece of turf, three feet by four in size, which had been exposed for many years to exactly the same conditions, supported twenty species of plants, and these belonged to eighteen genera and to eight orders, which shows how much these plants differed from each other. So it is with the plants and insects on small and uniform islets; and so in small ponds of fresh water. Farmers find that they can raise most food by a rotation of plants belonging to the most different orders: nature follows what may be called a simultaneous rotation. Most of the animals and plants which live close round any small piece of ground, could live on it (supposing it not to be in any way peculiar in its nature), and may be said to be striving to the utmost to live there; but, it is seen, that where they come into the closest competition with each other, the advantages of diversification of structure, with the accompanying differences of habit and constitution, determine that the inhabitants, which thus jostle each other most closely, shall, as a general rule, belong to what we call different genera and orders. The same principle is seen in the naturalisation of {115} plants through man's agency in foreign lands. It might have been expected that the plants which have succeeded in becoming naturalised in any land would generally have been closely allied to the indigenes; for these are commonly looked at as specially created and adapted for their own country. It might, also, perhaps have been expected that naturalised plants would have belonged to a few groups more especially adapted to certain stations in their new homes. But the case is very different; and Alph. De Candolle has well remarked in his great and admirable work, that floras gain by naturalisation, proportionally with the number of the native genera and species, far more in new genera than in new species. To give a single instance: in the last edition of Dr. Asa Gray's 'Manual of the Flora of the Northern United States,' 260 naturalised plants are enumerated, and these belong to 162 genera. We thus see that these naturalised plants are of a highly diversified nature. They differ, moreover, to a large extent from the indigenes, for out of the 162 genera, no less than 100 genera are not there indigenous, and thus a large proportional addition is made to the genera of these States. By considering the nature of the plants or animals which have struggled successfully with the indigenes of any country, and have there become naturalised, we may gain some crude idea in what manner some of the natives would have to be modified, in order to gain an advantage over the other natives; and we may at least safely infer that diversification of structure, amounting to new generic differences, would be profitable to them. The advantage of diversification in the inhabitants of the same region is, in fact, the same as that of the physiological division of labour in the organs of the same individual body--a subject so well elucidated by Milne {116} Edwards. No physiologist doubts that a stomach adapted to digest vegetable matter alone, or flesh alone, draws most nutriment from these substances. So in the general economy of any land, the more widely and perfectly the animals and plants are diversified for different habits of life, so will a greater number of individuals be capable of there supporting themselves. A set of animals, with their organisation but little diversified, could hardly compete with a set more perfectly diversified in structure. It may be doubted, for instance, whether the Australian marsupials, which are divided into groups differing but little from each other, and feebly representing, as Mr. Waterhouse and others have remarked, our carnivorous, ruminant, and rodent mammals, could successfully compete with these well-pronounced orders. In the Australian mammals, we see the process of diversification in an early and incomplete stage of development. After the foregoing discussion, which ought to have been much amplified, we may, I think, assume that the modified descendants of any one species will succeed by so much the better as they become more diversified in structure, and are thus enabled to encroach on places occupied by other beings. Now let us see how this principle of benefit being derived from divergence of character, combined with the principles of natural selection and of extinction, will tend to act. The accompanying diagram will aid us in understanding this rather perplexing subject. Let A to L represent the species of a genus large in its own country; these species are supposed to resemble each other in unequal degrees, as is so generally the case in nature, and as is represented in the diagram by the letters standing at unequal distances. I have said a large genus, because we have seen in the second chapter, {117} that on an average more of the species of large genera vary than of small genera; and the varying species of the large genera present a greater number of varieties. We have, also, seen that the species, which are the commonest and the most widely-diffused, vary more than rare species with restricted ranges. Let (A) be a common, widely-diffused, and varying species, belonging to a genus large in its own country. The little fan of diverging dotted lines of unequal lengths proceeding from (A), may represent its varying offspring. The variations are supposed to be extremely slight, but of the most diversified nature; they are not supposed all to appear simultaneously, but often after long intervals of time; nor are they all supposed to endure for equal periods. Only those variations which are in some way profitable will be preserved or naturally selected. And here the importance of the principle of benefit being derived from divergence of character comes in; for this will generally lead to the most different or divergent variations (represented by the outer dotted lines) being preserved and accumulated by natural selection. When a dotted line reaches one of the horizontal lines, and is there marked by a small numbered letter, a sufficient amount of variation is supposed to have been accumulated to have formed a fairly well-marked variety, such as would be thought worthy of record in a systematic work. [Illustration] The intervals between the horizontal lines in the diagram, may represent each a thousand generations; but it would have been better if each had represented ten thousand generations. After a thousand generations, species (A) is supposed to have produced two fairly well-marked varieties, namely a^1 and m^1. These two varieties will generally continue to be exposed to the same conditions which made their parents variable, {118} and the tendency to variability is in itself hereditary, consequently they will tend to vary, and generally to vary in nearly the same manner as their parents varied. Moreover, these two varieties, being only slightly modified forms, will tend to inherit those advantages which made their parent (A) more numerous than most of the other inhabitants of the same country; they will likewise partake of those more general advantages which made the genus to which the parent-species belonged, a large genus in its own country. And these circumstances we know to be favourable to the production of new varieties. If, then, these two varieties be variable, the most divergent of their variations will generally be preserved during the next thousand generations. And after this interval, variety a^1 is supposed in the diagram to have produced variety a^2, which will, owing to the principle of divergence, differ more from (A) than did variety a^1. Variety m^1 is supposed to have produced two varieties, namely m^2 and s^2, differing from each other, and more considerably from their common parent (A). We may continue the process by similar steps for any length of time; some of the varieties, after each thousand generations, producing only a single variety, but in a more and more modified condition, some producing two or three varieties, and some failing to produce any. Thus the varieties or modified descendants, proceeding from the common parent (A), will generally go on increasing in number and diverging in character. In the diagram the process is represented up to the ten-thousandth generation, and under a condensed and simplified form up to the fourteen-thousandth generation. But I must here remark that I do not suppose that the process ever goes on so regularly as is represented in the diagram, though in itself made somewhat irregular. {119} I am far from thinking that the most divergent varieties will invariably prevail and multiply: a medium form may often long endure, and may or may not produce more than one modified descendant; for natural selection will always act according to the nature of the places which are either unoccupied or not perfectly occupied by other beings; and this will depend on infinitely complex relations. But as a general rule, the more diversified in structure the descendants from any one species can be rendered, the more places they will be enabled to seize on, and the more their modified progeny will be increased. In our diagram the line of succession is broken at regular intervals by small numbered letters marking the successive forms which have become sufficiently distinct to be recorded as varieties. But these breaks are imaginary, and might have been inserted anywhere, after intervals long enough to have allowed the accumulation of a considerable amount of divergent variation. As all the modified descendants from a common and widely-diffused species, belonging to a large genus, will tend to partake of the same advantages which made their parent successful in life, they will generally go on multiplying in number as well as diverging in character: this is represented in the diagram by the several divergent branches proceeding from (A). The modified offspring from the later and more highly improved branches in the lines of descent, will, it is probable, often take the place of, and so destroy, the earlier and less improved branches: this is represented in the diagram by some of the lower branches not reaching to the upper horizontal lines. In some cases I do not doubt that the process of modification will be confined to a single line of descent, and the number of the descendants will not be increased; although the amount {120} of divergent modification may have been increased in the successive generations. This case would be represented in the diagram, if all the lines proceeding from (A) were removed, excepting that from a^1 to a^{10}. In the same way, for instance, the English race-horse and English pointer have apparently both gone on slowly diverging in character from their original stocks, without either having given off any fresh branches or races. After ten thousand generations, species (A) is supposed to have produced three forms, a^{10}, f^{10}, and m^{10}, which, from having diverged in character during the successive generations, will have come to differ largely, but perhaps unequally, from each other and from their common parent. If we suppose the amount of change between each horizontal line in our diagram to be excessively small, these three forms may still be only well-marked varieties; or they may have arrived at the doubtful category of sub-species; but we have only to suppose the steps in the process of modification to be more numerous or greater in amount, to convert these three forms into well-defined species: thus the diagram illustrates the steps by which the small differences distinguishing varieties are increased into the larger differences distinguishing species. By continuing the same process for a greater number of generations (as shown in the diagram in a condensed and simplified manner), we get eight species, marked by the letters between a^{14} and m^{14}, all descended from (A). Thus, as I believe, species are multiplied and genera are formed. In a large genus it is probable that more than one species would vary. In the diagram I have assumed that a second species (I) has produced, by analogous steps, after ten thousand generations, either two well-marked varieties (w^{10} and z^{10}) or two species, according to the amount of change supposed to be represented {121} between the horizontal lines. After fourteen thousand generations, six new species, marked by the letters n^{14} to z^{14}, are supposed to have been produced. In each genus, the species, which are already extremely different in character, will generally tend to produce the greatest number of modified descendants; for these will have the best chance of filling new and widely different places in the polity of nature: hence in the diagram I have chosen the extreme species (A), and the nearly extreme species (I), as those which have largely varied, and have given rise to new varieties and species. The other nine species (marked by capital letters) of our original genus, may for a long period continue to transmit unaltered descendants; and this is shown in the diagram by the dotted lines not prolonged far upwards from want of space. But during the process of modification, represented in the diagram, another of our principles, namely that of extinction, will have played an important part. As in each fully stocked country natural selection necessarily acts by the selected form having some advantage in the struggle for life over other forms, there will be a constant tendency in the improved descendants of any one species to supplant and exterminate in each stage of descent their predecessors and their original parent. For it should be remembered that the competition will generally be most severe between those forms which are most nearly related to each other in habits, constitution, and structure. Hence all the intermediate forms between the earlier and later states, that is between the less and more improved state of a species, as well as the original parent-species itself, will generally tend to become extinct. So it probably will be with many whole collateral lines of descent, which will be conquered by later and improved lines of descent. If, however, the {122} modified offspring of a species get into some distinct country, or become quickly adapted to some quite new station, in which child and parent do not come into competition, both may continue to exist. If then our diagram be assumed to represent a considerable amount of modification, species (A) and all the earlier varieties will have become extinct, having been replaced by eight new species (a^{14} to m^{14}); and (I) will have been replaced by six (n^{14} to z^{14}) new species. But we may go further than this. The original species of our genus were supposed to resemble each other in unequal degrees, as is so generally the case in nature; species (A) being more nearly related to B, C, and D, than to the other species; and species (I) more to G, H, K, L, than to the others. These two species (A) and (I), were also supposed to be very common and widely diffused species, so that they must originally have had some advantage over most of the other species of the genus. Their modified descendants, fourteen in number at the fourteen-thousandth generation, will probably have inherited some of the same advantages: they have also been modified and improved in a diversified manner at each stage of descent, so as to have become adapted to many related places in the natural economy of their country. It seems, therefore, to me extremely probable that they will have taken the places of, and thus exterminated, not only their parents (A) and (I), but likewise some of the original species which were most nearly related to their parents. Hence very few of the original species will have transmitted offspring to the fourteen-thousandth generation. We may suppose that only one (F), of the two species which were least closely related to the other nine original species, has transmitted descendants to this late stage of descent. {123} The new species in our diagram descended from the original eleven species, will now be fifteen in number. Owing to the divergent tendency of natural selection, the extreme amount of difference in character between species a^{14} and z^{14} will be much greater than that between the most different of the original eleven species. The new species, moreover, will be allied to each other in a widely different manner. Of the eight descendants from (A) the three marked a^{14}, q^{14}, p^{14}, will be nearly related from having recently branched off from a^{10}; b^{14} and f^{14}, from having diverged at an earlier period from a^5, will be in some degree distinct from the three first-named species; and lastly, o^{14}, e^{14} and m^{14}, will be nearly related one to the other, but from having diverged at the first commencement of the process of modification, will be widely different from the other five species, and may constitute a sub-genus or even a distinct genus. The six descendants from (I) will form two sub-genera or even genera. But as the original species (I) differed largely from (A), standing nearly at the extreme points of the original genus, the six descendants from (I) will, owing to inheritance alone, differ considerably from the eight descendants from (A); the two groups, moreover, are supposed to have gone on diverging in different directions. The intermediate species, also (and this is a very important consideration), which connected the original species (A) and (I), have all become, excepting (F), extinct, and have left no descendants. Hence the six new species descended from (I), and the eight descended from (A), will have to be ranked as very distinct genera, or even as distinct sub-families. Thus it is, as I believe, that two or more genera are produced by descent with modification, from two or more species of the same genus. And the two or {124} more parent-species are supposed to have descended from some one species of an earlier genus. In our diagram, this is indicated by the broken lines, beneath the capital letters, converging in sub-branches downwards towards a single point; this point representing a single species, the supposed single parent of our several new sub-genera and genera. It is worth while to reflect for a moment on the character of the new species F^{14}, which is supposed not to have diverged much in character, but to have retained the form of (F), either unaltered or altered only in a slight degree. In this case, its affinities to the other fourteen new species will be of a curious and circuitous nature. Having descended from a form which stood between the two parent-species (A) and (I), now supposed to be extinct and unknown, it will be in some degree intermediate in character between the two groups descended from these species. But as these two groups have gone on diverging in character from the type of their parents, the new species (F^{14}) will not be directly intermediate between them, but rather between types of the two groups; and every naturalist will be able to bring some such case before his mind. In the diagram, each horizontal line has hitherto been supposed to represent a thousand generations, but each may represent a million or hundred million generations, and likewise a section of the successive strata of the earth's crust including extinct remains. We shall, when we come to our chapter on Geology, have to refer again to this subject, and I think we shall then see that the diagram throws light on the affinities of extinct beings, which, though generally belonging to the same orders, or families, or genera, with those now living, yet are often, in some degree, intermediate in character between existing groups; and we can understand this fact, for {125} the extinct species lived at very ancient epochs when the branching lines of descent had diverged less. I see no reason to limit the process of modification, as now explained, to the formation of genera alone. If, in our diagram, we suppose the amount of change represented by each successive group of diverging dotted lines to be very great, the forms marked a^{14} to p^{14}, those marked b^{14} and f^{14}, and those marked o^{14} to m^{14}, will form three very distinct genera. We shall also have two very distinct genera descended from (I); and as these latter two genera, both from continued divergence of character and from inheritance from a different parent, will differ widely from the three genera descended from (A), the two little groups of genera will form two distinct families, or even orders, according to the amount of divergent modification supposed to be represented in the diagram. And the two new families, or orders, will have descended from two species of the original genus; and these two species are supposed to have descended from one species of a still more ancient and unknown genus. We have seen that in each country it is the species of the larger genera which oftenest present varieties or incipient species. This, indeed, might have been expected; for as natural selection acts through one form having some advantage over other forms in the struggle for existence, it will chiefly act on those which already have some advantage; and the largeness of any group shows that its species have inherited from a common ancestor some advantage in common. Hence, the struggle for the production of new and modified descendants, will mainly lie between the larger groups, which are all trying to increase in number. One large group will slowly conquer another large group, reduce its numbers, and thus lessen its chance of further variation and improvement. Within the same large {126} group, the later and more highly perfected sub-groups, from branching out and seizing on many new places in the polity of Nature, will constantly tend to supplant and destroy the earlier and less improved sub-groups. Small and broken groups and sub-groups will finally disappear. Looking to the future, we can predict that the groups of organic beings which are now large and triumphant, and which are least broken up, that is, which as yet have suffered least extinction, will for a long period continue to increase. But which groups will ultimately prevail, no man can predict; for we well know that many groups, formerly most extensively developed, have now become extinct. Looking still more remotely to the future, we may predict that, owing to the continued and steady increase of the larger groups, a multitude of smaller groups will become utterly extinct, and leave no modified descendants; and consequently that of the species living at any one period, extremely few will transmit descendants to a remote futurity. I shall have to return to this subject in the chapter on Classification, but I may add that on this view of extremely few of the more ancient species having transmitted descendants, and on the view of all the descendants of the same species making a class, we can understand how it is that there exist but very few classes in each main division of the animal and vegetable kingdoms. Although extremely few of the most ancient species may now have living and modified descendants, yet at the most remote geological period, the earth may have been as well peopled with many species of many genera, families, orders, and classes, as at the present day. _Summary of Chapter._--If during the long course of ages and under varying conditions of life, organic beings {127} vary at all in the several parts of their organisation, and I think this cannot be disputed; if there be, owing to the high geometrical ratio of increase of each species, a severe struggle for life at some age, season, or year, and this certainly cannot be disputed; then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of existence, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, I think it would be a most extraordinary fact if no variation ever had occurred useful to each being's own welfare, in the same manner as so many variations have occurred useful to man. But if variations useful to any organic being do occur, assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly characterised. This principle of preservation, I have called, for the sake of brevity, Natural Selection; and it leads to the improvement of each creature in relation to its organic and inorganic conditions of life. Natural selection, on the principle of qualities being inherited at corresponding ages, can modify the egg, seed, or young, as easily as the adult. Amongst many animals, sexual selection will give its aid to ordinary selection, by assuring to the most vigorous and best adapted males the greatest number of offspring. Sexual selection will also give characters useful to the males alone, in their struggles with other males. Whether natural selection has really thus acted in nature, in modifying and adapting the various forms of life to their several conditions and stations, must be judged of by the general tenour and balance of evidence given in the following chapters. But we already see how it entails extinction; and how largely extinction {128} has acted in the world's history, geology plainly declares. Natural selection, also, leads to divergence of character; for more living beings can be supported on the same area the more they diverge in structure, habits, and constitution, of which we see proof by looking to the inhabitants of any small spot or to naturalised productions. Therefore during the modification of the descendants of any one species, and during the incessant struggle of all species to increase in numbers, the more diversified these descendants become, the better will be their chance of succeeding in the battle for life. Thus the small differences distinguishing varieties of the same species, steadily tend to increase till they come to equal the greater differences between species of the same genus, or even of distinct genera. We have seen that it is the common, the widely-diffused, and widely-ranging species, belonging to the larger genera, which vary most; and these tend to transmit to their modified offspring that superiority which now makes them dominant in their own countries. Natural selection, as has just been remarked, leads to divergence of character and to much extinction of the less improved and intermediate forms of life. On these principles, I believe, the nature of the affinities of all organic beings may be explained. It is a truly wonderful fact--the wonder of which we are apt to overlook from familiarity--that all animals and all plants throughout all time and space should be related to each other in group subordinate to group, in the manner which we everywhere behold--namely, varieties of the same species most closely related together, species of the same genus less closely and unequally related together, forming sections and sub-genera, species of distinct genera much less closely related, and genera related in different degrees, forming {129} sub-families, families, orders, sub-classes, and classes. The several subordinate groups in any class cannot be ranked in a single file, but seem rather to be clustered round points, and these round other points, and so on in almost endless cycles. On the view that each species has been independently created, I can see no explanation of this great fact in the classification of all organic beings; but, to the best of my judgment, it is explained through inheritance and the complex action of natural selection, entailing extinction and divergence of character, as we have seen illustrated in the diagram. The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species. At each period of growth all the growing twigs have tried to branch out on all sides, and to overtop and kill the surrounding twigs and branches, in the same manner as species and groups of species have tried to overmaster other species in the great battle for life. The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was small, budding twigs; and this connexion of the former and present buds by ramifying branches may well represent the classification of all extinct and living species in groups subordinate to groups. Of the many twigs which flourished when the tree was a mere bush, only two or three, now grown into great branches, yet survive and bear all the other branches; so with the species which lived during long-past geological periods, very few now have living and modified descendants. From the first growth of the tree, many a limb and branch has decayed and dropped off; and these lost branches of various {130} sizes may represent those whole orders, families, and genera which have now no living representatives, and which are known to us only from having been found in a fossil state. As we here and there see a thin straggling branch springing from a fork low down in a tree, and which by some chance has been favoured and is still alive on its summit, so we occasionally see an animal like the Ornithorhynchus or Lepidosiren, which in some small degree connects by its affinities two large branches of life, and which has apparently been saved from fatal competition by having inhabited a protected station. As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications. * * * * * {131} CHAPTER V. LAWS OF VARIATION. Effects of external conditions--Use and disuse, combined with natural selection; organs of flight and of vision--Acclimatisation--Correlation of growth--Compensation and economy of growth--False correlations--Multiple, rudimentary, and lowly organised structures variable--Parts developed in an unusual manner are highly variable: specific characters more variable than generic: secondary sexual characters variable--Species of the same genus vary in an analogous manner--Reversions to long-lost characters--Summary. I have hitherto sometimes spoken as if the variations--so common and multiform in organic beings under domestication, and in a lesser degree in those in a state of nature--had been due to chance. This, of course, is a wholly incorrect expression, but it serves to acknowledge plainly our ignorance of the cause of each particular variation. Some authors believe it to be as much the function of the reproductive system to produce individual differences, or very slight deviations of structure, as to make the child like its parents. But the much greater variability, as well as the greater frequency of monstrosities, under domestication or cultivation, than under nature, leads me to believe that deviations of structure are in some way due to the nature of the conditions of life, to which the parents and their more remote ancestors have been exposed during several generations. I have remarked in the first chapter--but a long catalogue of facts which cannot be here given would be necessary to show the truth of the remark--that the reproductive system is eminently susceptible to changes in the conditions of life; and to {132} this system being functionally disturbed in the parents, I chiefly attribute the varying or plastic condition of the offspring. The male and female sexual elements seem to be affected before that union takes place which is to form a new being. In the case of "sporting" plants, the bud, which in its earliest condition does not apparently differ essentially from an ovule, is alone affected. But why, because the reproductive system is disturbed, this or that part should vary more or less, we are profoundly ignorant. Nevertheless, we can here and there dimly catch a faint ray of light, and we may feel sure that there must be some cause for each deviation of structure, however slight. How much direct effect difference of climate, food, &c., produces on any being is extremely doubtful. My impression is, that the effect is extremely small in the case of animals, but perhaps rather more in that of plants. We may, at least, safely conclude that such influences cannot have produced the many striking and complex co-adaptations of structure between one organic being and another, which we see everywhere throughout nature. Some little influence may be attributed to climate, food, &c.: thus, E. Forbes speaks confidently that shells at their southern limit, and when living in shallow water, are more brightly coloured than those of the same species further north or from greater depths. Gould believes that birds of the same species are more brightly coloured under a clear atmosphere, than when living on islands or near the coast. So with insects, Wollaston is convinced that residence near the sea affects their colours. Moquin-Tandon gives a list of plants which when growing near the sea-shore have their leaves in some degree fleshy, though not elsewhere fleshy. Several other such cases could be given. The fact of varieties of one species, when they range {133} into the zone of habitation of other species, often acquiring in a very slight degree some of the characters of such species, accords with our view that species of all kinds are only well-marked and permanent varieties. Thus the species of shells which are confined to tropical and shallow seas are generally brighter-coloured than those confined to cold and deeper seas. The birds which are confined to continents are, according to Mr. Gould, brighter-coloured than those of islands. The insect-species confined to sea-coasts, as every collector knows, are often brassy or lurid. Plants which live exclusively on the sea-side are very apt to have fleshy leaves. He who believes in the creation of each species, will have to say that this shell, for instance, was created with bright colours for a warm sea; but that this other shell became bright-coloured by variation when it ranged into warmer or shallower waters. When a variation is of the slightest use to a being, we cannot tell how much of it to attribute to the accumulative action of natural selection, and how much to the conditions of life. Thus, it is well known to furriers that animals of the same species have thicker and better fur the more severe the climate is under which they have lived; but who can tell how much of this difference may be due to the warmest-clad individuals having been favoured and preserved during many generations, and how much to the direct action of the severe climate? for it would appear that climate has some direct action on the hair of our domestic quadrupeds. Instances could be given of the same variety being produced under conditions of life as different as can well be conceived; and, on the other hand, of different varieties being produced from the same species under the same conditions. Such facts show how indirectly {134} the conditions of life act. Again, innumerable instances are known to every naturalist of species keeping true, or not varying at all, although living under the most opposite climates. Such considerations as these incline me to lay very little weight on the direct action of the conditions of life. Indirectly, as already remarked, they seem to play an important part in affecting the reproductive system, and in thus inducing variability; and natural selection will then accumulate all profitable variations, however slight, until they become plainly developed and appreciable by us. _Effects of Use and Disuse._--From the facts alluded to in the first chapter, I think there can be little doubt that use in our domestic animals strengthens and enlarges certain parts, and disuse diminishes them; and that such modifications are inherited. Under free nature, we can have no standard of comparison, by which to judge of the effects of long-continued use or disuse, for we know not the parent-forms; but many animals have structures which can be explained by the effects of disuse. As Professor Owen has remarked, there is no greater anomaly in nature than a bird that cannot fly; yet there are several in this state. The logger-headed duck of South America can only flap along the surface of the water, and has its wings in nearly the same condition as the domestic Aylesbury duck. As the larger ground-feeding birds seldom take flight except to escape danger, I believe that the nearly wingless condition of several birds, which now inhabit or have lately inhabited several oceanic islands, tenanted by no beast of prey, has been caused by disuse. The ostrich indeed inhabits continents and is exposed to danger from which it cannot escape by flight, but by kicking it can defend itself from enemies, as well as any of the smaller {135} quadrupeds. We may imagine that the early progenitor of the ostrich had habits like those of a bustard, and that as natural selection increased in successive generations the size and weight of its body, its legs were used more, and its wings less, until they became incapable of flight. Kirby has remarked (and I have observed the same fact) that the anterior tarsi, or feet, of many male dung-feeding beetles are very often broken off; he examined seventeen specimens in his own collection, and not one had even a relic left. In the Onites apelles the tarsi are so habitually lost, that the insect has been described as not having them. In some other genera they are present, but in a rudimentary condition. In the Ateuchus or sacred beetle of the Egyptians, they are totally deficient. There is not sufficient evidence to induce me to believe that mutilations are ever inherited; and I should prefer explaining the entire absence of the anterior tarsi in Ateuchus, and their rudimentary condition in some other genera, by the long-continued effects of disuse in their progenitors; for as the tarsi are almost always lost in many dung-feeding beetles, they must be lost early in life, and therefore cannot be much used by these insects. In some cases we might easily put down to disuse modifications of structure which are wholly, or mainly, due to natural selection. Mr. Wollaston has discovered the remarkable fact that 200 beetles, out of the 550 species inhabiting Madeira, are so far deficient in wings that they cannot fly; and that of the twenty-nine endemic genera, no less than twenty-three genera have all their species in this condition! Several facts, namely, that beetles in many parts of the world are frequently blown to sea and perish; that the beetles in Madeira, as observed by Mr. Wollaston, lie much concealed, {136} until the wind lulls and the sun shines; that the proportion of wingless beetles is larger on the exposed Desertas than in Madeira itself; and especially the extraordinary fact, so strongly insisted on by Mr. Wollaston, of the almost entire absence of certain large groups of beetles, elsewhere excessively numerous, and which groups have habits of life almost necessitating frequent flight;--these several considerations have made me believe that the wingless condition of so many Madeira beetles is mainly due to the action of natural selection, but combined probably with disuse. For during thousands of successive generations each individual beetle which flew least, either from its wings having been ever so little less perfectly developed or from indolent habit, will have had the best chance of surviving from not being blown out to sea; and, on the other hand, those beetles which most readily took to flight would oftenest have been blown to sea and thus have been destroyed. The insects in Madeira which are not ground-feeders, and which, as the flower-feeding coleoptera and lepidoptera, must habitually use their wings to gain their subsistence, have, as Mr. Wollaston suspects, their wings not at all reduced, but even enlarged. This is quite compatible with the action of natural selection. For when a new insect first arrived on the island, the tendency of natural selection to enlarge or to reduce the wings, would depend on whether a greater number of individuals were saved by successfully battling with the winds, or by giving up the attempt and rarely or never flying. As with mariners shipwrecked near a coast, it would have been better for the good swimmers if they had been able to swim still further, whereas it would have been better for the bad swimmers if they had not been able to swim at all and had stuck to the wreck. {137} The eyes of moles and of some burrowing rodents are rudimentary in size, and in some cases are quite covered up by skin and fur. This state of the eyes is probably due to gradual reduction from disuse, but aided perhaps by natural selection. In South America, a burrowing rodent, the tuco-tuco, or Ctenomys, is even more subterranean in its habits than the mole; and I was assured by a Spaniard, who had often caught them, that they were frequently blind; one which I kept alive was certainly in this condition, the cause, as appeared on dissection, having been inflammation of the nictitating membrane. As frequent inflammation of the eyes must be injurious to any animal, and as eyes are certainly not indispensable to animals with subterranean habits, a reduction in their size with the adhesion of the eyelids and growth of fur over them, might in such case be an advantage; and if so, natural selection would constantly aid the effects of disuse. It is well known that several animals, belonging to the most different classes, which inhabit the caves of Styria and of Kentucky, are blind. In some of the crabs the foot-stalk for the eye remains, though the eye is gone; the stand for the telescope is there, though the telescope with its glasses has been lost. As it is difficult to imagine that eyes, though useless, could be in any way injurious to animals living in darkness, I attribute their loss wholly to disuse. In one of the blind animals, namely, the cave-rat, the eyes are of immense size; and Professor Silliman thought that it regained, after living some days in the light, some slight power of vision. In the same manner as in Madeira the wings of some of the insects have been enlarged, and the wings of others have been reduced by natural selection aided by use and disuse, so in the case of the cave-rat natural selection seems to have struggled with the loss of light and {138} to have increased the size of the eyes; whereas with all the other inhabitants of the caves, disuse by itself seems to have done its work. It is difficult to imagine conditions of life more similar than deep limestone caverns under a nearly similar climate; so that on the common view of the blind animals having been separately created for the American and European caverns, close similarity in their organisation and affinities might have been expected; but, as Schiödte and others have remarked, this is not the case, and the cave-insects of the two continents are not more closely allied than might have been anticipated from the general resemblance of the other inhabitants of North America and Europe. On my view we must suppose that American animals, having ordinary powers of vision, slowly migrated by successive generations from the outer world into the deeper and deeper recesses of the Kentucky caves, as did European animals into the caves of Europe. We have some evidence of this gradation of habit; for, as Schiödte remarks, "animals not far remote from ordinary forms, prepare the transition from light to darkness. Next follow those that are constructed for twilight; and, last of all, those destined for total darkness." By the time that an animal had reached, after numberless generations, the deepest recesses, disuse will on this view have more or less perfectly obliterated its eyes, and natural selection will often have effected other changes, such as an increase in the length of the antennæ or palpi, as a compensation for blindness. Notwithstanding such modifications, we might expect still to see in the cave-animals of America, affinities to the other inhabitants of that continent, and in those of Europe, to the inhabitants of the European continent. And this is the case with some of the American cave-animals, as I hear from {139} Professor Dana; and some of the European cave-insects are very closely allied to those of the surrounding country. It would be most difficult to give any rational explanation of the affinities of the blind cave-animals to the other inhabitants of the two continents on the ordinary view of their independent creation. That several of the inhabitants of the caves of the Old and New Worlds should be closely related, we might expect from the well-known relationship of most of their other productions. Far from feeling any surprise that some of the cave-animals should be very anomalous, as Agassiz has remarked in regard to the blind fish, the Amblyopsis, and as is the case with the blind Proteus with reference to the reptiles of Europe, I am only surprised that more wrecks of ancient life have not been preserved, owing to the less severe competition to which the inhabitants of these dark abodes will probably have been exposed. _Acclimatisation._--Habit is hereditary with plants, as in the period of flowering, in the amount of rain requisite for seeds to germinate, in the time of sleep, &c., and this leads me to say a few words on acclimatisation. As it is extremely common for species of the same genus to inhabit very hot and very cold countries, and as I believe that all the species of the same genus have descended from a single parent, if this view be correct, acclimatisation must be readily effected during long-continued descent. It is notorious that each species is adapted to the climate of its own home: species from an arctic or even from a temperate region cannot endure a tropical climate, or conversely. So again, many succulent plants cannot endure a damp climate. But the degree of adaptation of species to the climates under which they live is often overrated. {140} We may infer this from our frequent inability to predict whether or not an imported plant will endure our climate, and from the number of plants and animals brought from warmer countries which here enjoy good health. We have reason to believe that species in a state of nature are limited in their ranges by the competition of other organic beings quite as much as, or more than, by adaptation to particular climates. But whether or not the adaptation be generally very close, we have evidence, in the case of some few plants, of their becoming, to a certain extent, naturally habituated to different temperatures, or becoming acclimatised: thus the pines and rhododendrons, raised from seed collected by Dr. Hooker from trees growing at different heights on the Himalaya, were found in this country to possess different constitutional powers of resisting cold. Mr. Thwaites informs me that he has observed similar facts in Ceylon, and analogous observations have been made by Mr. H. C. Watson on European species of plants brought from the Azores to England. In regard to animals, several authentic cases could be given of species within historical times having largely extended their range from warmer to cooler latitudes, and conversely; but we do not positively know that these animals were strictly adapted to their native climate, but in all ordinary cases we assume such to be the case; nor do we know that they have subsequently become acclimatised to their new homes. As I believe that our domestic animals were originally chosen by uncivilised man because they were useful and bred readily under confinement, and not because they were subsequently found capable of far-extended transportation, I think the common and extraordinary capacity in our domestic animals of not only withstanding the most different climates but of being perfectly {141} fertile (a far severer test) under them, may be used as an argument that a large proportion of other animals, now in a state of nature, could easily be brought to bear widely different climates. We must not, however, push the foregoing argument too far, on account of the probable origin of some of our domestic animals from several wild stocks: the blood, for instance, of a tropical and arctic wolf or wild dog may perhaps be mingled in our domestic breeds. The rat and mouse cannot be considered as domestic animals, but they have been transported by man to many parts of the world, and now have a far wider range than any other rodent, living free under the cold climate of Faroe in the north and of the Falklands in the south, and on many islands in the torrid zones. Hence I am inclined to look at adaptation to any special climate as a quality readily grafted on an innate wide flexibility of constitution, which is common to most animals. On this view, the capacity of enduring the most different climates by man himself and by his domestic animals, and such facts as that former species of the elephant and rhinoceros were capable of enduring a glacial climate, whereas the living species are now all tropical or sub-tropical in their habits, ought not to be looked at as anomalies, but merely as examples of a very common flexibility of constitution, brought, under peculiar circumstances, into play. How much of the acclimatisation of species to any peculiar climate is due to mere habit, and how much to the natural selection of varieties having different innate constitutions, and how much to both means combined, is a very obscure question. That habit or custom has some influence I must believe, both from analogy, and from the incessant advice given in agricultural works, even in the ancient Encyclopædias of China, to be very {142} cautious in transposing animals from one district to another; for it is not likely that man should have succeeded in selecting so many breeds and sub-breeds with constitutions specially fitted for their own districts: the result must, I think, be due to habit. On the other hand, I can see no reason to doubt that natural selection will continually tend to preserve those individuals which are born with constitutions best adapted to their native countries. In treatises on many kinds of cultivated plants, certain varieties are said to withstand certain climates better than others: this is very strikingly shown in works on fruit trees published in the United States, in which certain varieties are habitually recommended for the northern, and others for the southern States; and as most of these varieties are of recent origin, they cannot owe their constitutional differences to habit. The case of the Jerusalem artichoke, which is never propagated by seed, and of which consequently new varieties have not been produced, has even been advanced--for it is now as tender as ever it was--as proving that acclimatisation cannot be effected! The case, also, of the kidney-bean has been often cited for a similar purpose, and with much greater weight; but until some one will sow, during a score of generations, his kidney-beans so early that a very large proportion are destroyed by frost, and then collect seed from the few survivors, with care to prevent accidental crosses, and then again get seed from these seedlings, with the same precautions, the experiment cannot be said to have been even tried. Nor let it be supposed that no differences in the constitution of seedling kidney-beans ever appear, for an account has been published how much more hardy some seedlings appeared to be than others. On the whole, I think we may conclude that habit, {143} use, and disuse, have, in some cases, played a considerable part in the modification of the constitution, and of the structure of various organs; but that the effects of use and disuse have often been largely combined with, and sometimes overmastered by the natural selection of innate variations. _Correlation of Growth._--I mean by this expression that the whole organisation is so tied together during its growth and development, that when slight variations in any one part occur, and are accumulated through natural selection, other parts become modified. This is a very important subject, most imperfectly understood. The most obvious case is, that modifications accumulated solely for the good of the young or larva, will, it may safely be concluded, affect the structure of the adult; in the same manner as any malconformation affecting the early embryo, seriously affects the whole organisation of the adult. The several parts of the body which are homologous, and which, at an early embryonic period, are alike, seem liable to vary in an allied manner: we see this in the right and left sides of the body varying in the same manner; in the front and hind legs, and even in the jaws and limbs, varying together, for the lower jaw is believed to be homologous with the limbs. These tendencies, I do not doubt, may be mastered more or less completely by natural selection: thus a family of stags once existed with an antler only on one side; and if this had been of any great use to the breed it might probably have been rendered permanent by natural selection. Homologous parts, as has been remarked by some authors, tend to cohere; this is often seen in monstrous plants; and nothing is more common than the union of homologous parts in normal structures, as the union of {144} the petals of the corolla into a tube. Hard parts seem to affect the form of adjoining soft parts; it is believed by some authors that the diversity in the shape of the pelvis in birds causes the remarkable diversity in the shape of their kidneys. Others believe that the shape of the pelvis in the human mother influences by pressure the shape of the head of the child. In snakes, according to Schlegel, the shape of the body and the manner of swallowing determine the position of several of the most important viscera. The nature of the bond of correlation is very frequently quite obscure. M. Is. Geoffroy St. Hilaire has forcibly remarked, that certain malconformations very frequently, and that others rarely coexist, without our being able to assign any reason. What can be more singular than the relation between blue eyes and deafness in cats, and the tortoise-shell colour with the female sex; the feathered feet and skin between the outer toes in pigeons, and the presence of more or less down on the young birds when first hatched, with the future colour of their plumage; or, again, the relation between the hair and teeth in the naked Turkish dog, though here probably homology comes into play? With respect to this latter case of correlation, I think it can hardly be accidental, that if we pick out the two orders of mammalia which are most abnormal in their dermal covering, viz. Cetacea (whales) and Edentata (armadilloes, scaly anteaters, &c.), that these are likewise the most abnormal in their teeth. I know of no case better adapted to show the importance of the laws of correlation in modifying important structures, independently of utility and, therefore, of natural selection, than that of the difference between the outer and inner flowers in some Compositous and Umbelliferous plants. Every one knows the {145} difference in the ray and central florets of, for instance, the daisy, and this difference is often accompanied with the abortion of parts of the flower. But, in some Compositous plants, the seeds also differ in shape and sculpture; and even the ovary itself, with its accessory parts, differs, as has been described by Cassini. These differences have been attributed by some authors to pressure, and the shape of the seeds in the ray-florets in some Compositæ countenances this idea; but, in the case of the corolla of the Umbelliferæ, it is by no means, as Dr. Hooker informs me, in species with the densest heads that the inner and outer flowers most frequently differ. It might have been thought that the development of the ray-petals by drawing nourishment from certain other parts of the flower had caused their abortion; but in some Compositæ there is a difference in the seeds of the outer and inner florets without any difference in the corolla. Possibly, these several differences may be connected with some difference in the flow of nutriment towards the central and external flowers: we know, at least, that in irregular flowers, those nearest to the axis are oftenest subject to peloria, and become regular. I may add, as an instance of this, and of a striking case of correlation, that I have recently observed in some garden pelargoniums, that the central flower of the truss often loses the patches of darker colour in the two upper petals; and that when this occurs, the adherent nectary is quite aborted; when the colour is absent from only one of the two upper petals, the nectary is only much shortened. With respect to the difference in the corolla of the central and exterior flowers of a head or umbel, I do not feel at all sure that C. C. Sprengel's idea that the ray-florets serve to attract insects, whose agency is highly advantageous in the fertilisation of plants of {146} these two orders, is so far-fetched, as it may at first appear: and if it be advantageous, natural selection may have come into play. But in regard to the differences both in the internal and external structure of the seeds, which are not always correlated with any differences in the flowers, it seems impossible that they can be in any way advantageous to the plant: yet in the Umbelliferæ these differences are of such apparent importance--the seeds being in some cases, according to Tausch, orthospermous in the exterior flowers and coelospermous in the central flowers,--that the elder De Candolle founded his main divisions of the order on analogous differences. Hence we see that modifications of structure, viewed by systematists as of high value, may be wholly due to unknown laws of correlated growth, and without being, as far as we can see, of the slightest service to the species. We may often falsely attribute to correlation of growth, structures which are common to whole groups of species, and which in truth are simply due to inheritance; for an ancient progenitor may have acquired through natural selection some one modification in structure, and, after thousands of generations, some other and independent modification; and these two modifications, having been transmitted to a whole group of descendants with diverse habits, would naturally be thought to be correlated in some necessary manner. So, again, I do not doubt that some apparent correlations, occurring throughout whole orders, are entirely due to the manner alone in which natural selection can act. For instance, Alph. De Candolle has remarked that winged seeds are never found in fruits which do not open: I should explain the rule by the fact that seeds could not gradually become winged through natural selection, except in fruits which opened; so that the individual plants producing {147} seeds which were a little better fitted to be wafted further, might get an advantage over those producing seed less fitted for dispersal; and this process could not possibly go on in fruit which did not open. The elder Geoffroy and Goethe propounded, at about the same period, their law of compensation or balancement of growth; or, as Goethe expressed it, "in order to spend on one side, nature is forced to economise on the other side." I think this holds true to a certain extent with our domestic productions: if nourishment flows to one part or organ in excess, it rarely flows, at least in excess, to another part; thus it is difficult to get a cow to give much milk and to fatten readily. The same varieties of the cabbage do not yield abundant and nutritious foliage and a copious supply of oil-bearing seeds. When the seeds in our fruits become atrophied, the fruit itself gains largely in size and quality. In our poultry, a large tuft of feathers on the head is generally accompanied by a diminished comb, and a large beard by diminished wattles. With species in a state of nature it can hardly be maintained that the law is of universal application; but many good observers, more especially botanists, believe in its truth. I will not, however, here give any instances, for I see hardly any way of distinguishing between the effects, on the one hand, of a part being largely developed through natural selection and another and adjoining part being reduced by this same process or by disuse, and, on the other hand, the actual withdrawal of nutriment from one part owing to the excess of growth in another and adjoining part. I suspect, also, that some of the cases of compensation which have been advanced, and likewise some other facts, may be merged under a more general principle, namely, that natural selection is continually trying to economise in every part of the organisation. If under {148} changed conditions of life a structure before useful becomes less useful, any diminution, however slight, in its development, will be seized on by natural selection, for it will profit the individual not to have its nutriment wasted in building up an useless structure. I can thus only understand a fact with which I was much struck when examining cirripedes, and of which many other instances could be given: namely, that when a cirripede is parasitic within another and is thus protected, it loses more or less completely its own shell or carapace. This is the case with the male Ibla, and in a truly extraordinary manner with the Proteolepas: for the carapace in all other cirripedes consists of the three highly-important anterior segments of the head enormously developed, and furnished with great nerves and muscles; but in the parasitic and protected Proteolepas, the whole anterior part of the head is reduced to the merest rudiment attached to the bases of the prehensile antennæ. Now the saving of a large and complex structure, when rendered superfluous by the parasitic habits of the Proteolepas, though effected by slow steps, would be a decided advantage to each successive individual of the species; for in the struggle for life to which every animal is exposed, each individual Proteolepas would have a better chance of supporting itself, by less nutriment being wasted in developing a structure now become useless. Thus, as I believe, natural selection will always succeed in the long run in reducing and saving every part of the organisation, as soon as it is rendered superfluous, without by any means causing some other part to be largely developed in a corresponding degree. And, conversely, that natural selection may perfectly well succeed in largely developing any organ, without requiring as a necessary compensation the reduction of some adjoining part. {149} It seems to be a rule, as remarked by Is. Geoffroy St. Hilaire, both in varieties and in species, that when any part or organ is repeated many times in the structure of the same individual (as the vertebræ in snakes, and the stamens in polyandrous flowers) the number is variable; whereas the number of the same part or organ, when it occurs in lesser numbers, is constant. The same author and some botanists have further remarked that multiple parts are also very liable to variation in structure. Inasmuch as this "vegetative repetition," to use Prof. Owen's expression, seems to be a sign of low organisation, the foregoing remark seems connected with the very general opinion of naturalists, that beings low in the scale of nature are more variable than those which are higher. I presume that lowness in this case means that the several parts of the organisation have been but little specialised for particular functions; and as long as the same part has to perform diversified work, we can perhaps see why it should remain variable, that is, why natural selection should have preserved or rejected each little deviation of form less carefully than when the part has to serve for one special purpose alone. In the same way that a knife which has to cut all sorts of things may be of almost any shape; whilst a tool for some particular object had better be of some particular shape. Natural selection, it should never be forgotten, can act on each part of each being, solely through and for its advantage. Rudimentary parts, it has been stated by some authors, and I believe with truth, are apt to be highly variable. We shall have to recur to the general subject of rudimentary and aborted organs; and I will here only add that their variability seems to be owing to their uselessness, and therefore to natural selection having no power to check deviations in their structure. Thus {150} rudimentary parts are left to the free play of the various laws of growth, to the effects of long-continued disuse, and to the tendency to reversion. _A part developed in any species in an extraordinary degree or manner, in comparison with the same part in allied species, tends to be highly variable._--Several years ago I was much struck with a remark, nearly to the above effect, published by Mr. Waterhouse. I infer also from an observation made by Professor Owen, with respect to the length of the arms of the ourang-outang, that he has come to a nearly similar conclusion. It is hopeless to attempt to convince any one of the truth of this proposition without giving the long array of facts which I have collected, and which cannot possibly be here introduced. I can only state my conviction that it is a rule of high generality. I am aware of several causes of error, but I hope that I have made due allowance for them. It should be understood that the rule by no means applies to any part, however unusually developed, unless it be unusually developed in comparison with the same part in closely allied species. Thus, the bat's wing is a most abnormal structure in the class mammalia; but the rule would not here apply, because there is a whole group of bats having wings; it would apply only if some one species of bat had its wings developed in some remarkable manner in comparison with the other species of the same genus. The rule applies very strongly in the case of secondary sexual characters, when displayed in any unusual manner. The term, secondary sexual characters, used by Hunter, applies to characters which are attached to one sex, but are not directly connected with the act of reproduction. The rule applies to males and females; but as females more rarely offer remarkable secondary sexual characters, it applies {151} more rarely to them. The rule being so plainly applicable in the case of secondary sexual characters, may be due to the great variability of these characters, whether or not displayed in any unusual manner--of which fact I think there can be little doubt. But that our rule is not confined to secondary sexual characters is clearly shown in the case of hermaphrodite cirripedes; and I may here add, that I particularly attended to Mr. Waterhouse's remark, whilst investigating this Order, and I am fully convinced that the rule almost invariably holds good with cirripedes. I shall, in my future work, give a list of the more remarkable cases; I will here only briefly give one, as it illustrates the rule in its largest application. The opercular valves of sessile cirripedes (rock barnacles) are, in every sense of the word, very important structures, and they differ extremely little even in different genera; but in the several species of one genus, Pyrgoma, these valves present a marvellous amount of diversification: the homologous valves in the different species being sometimes wholly unlike in shape; and the amount of variation in the individuals of several of the species is so great, that it is no exaggeration to state that the varieties differ more from each other in the characters of these important valves than do other species of distinct genera. As birds within the same country vary in a remarkably small degree, I have particularly attended to them, and the rule seems to me certainly to hold good in this class. I cannot make out that it applies to plants, and this would seriously have shaken my belief in its truth, had not the great variability in plants made it particularly difficult to compare their relative degrees of variability. When we see any part or organ developed in a remarkable degree or manner in any species, the fair {152} presumption is that it is of high importance to that species; nevertheless the part in this case is eminently liable to variation. Why should this be so? On the view that each species has been independently created, with all its parts as we now see them, I can see no explanation. But on the view that groups of species have descended from other species, and have been modified through natural selection, I think we can obtain some light. In our domestic animals, if any part, or the whole animal, be neglected and no selection be applied, that part (for instance, the comb in the Dorking fowl) or the whole breed will cease to have a nearly uniform character. The breed will then be said to have degenerated. In rudimentary organs, and in those which have been but little specialised for any particular purpose, and perhaps in polymorphic groups, we see a nearly parallel natural case; for in such cases natural selection either has not or cannot come into full play, and thus the organisation is left in a fluctuating condition. But what here more especially concerns us is, that in our domestic animals those points, which at the present time are undergoing rapid change by continued selection, are also eminently liable to variation. Look at the breeds of the pigeon; see what a prodigious amount of difference there is in the beak of the different tumblers, in the beak and wattle of the different carriers, in the carriage and tail of our fantails, &c., these being the points now mainly attended to by English fanciers. Even in the sub-breeds, as in the short-faced tumbler, it is notoriously difficult to breed them nearly to perfection, and frequently individuals are born which depart widely from the standard. There may be truly said to be a constant struggle going on between, on the one hand, the tendency to reversion to a less modified state, as well as an innate tendency to further {153} variability of all kinds, and, on the other hand, the power of steady selection to keep the breed true. In the long run selection gains the day, and we do not expect to fail so far as to breed a bird as coarse as a common tumbler from a good short-faced strain. But as long as selection is rapidly going on, there may always be expected to be much variability in the structure undergoing modification. It further deserves notice that these variable characters, produced by man's selection, sometimes become attached, from causes quite unknown to us, more to one sex than to the other, generally to the male sex, as with the wattle of carriers and the enlarged crop of pouters. Now let us turn to nature. When a part has been developed in an extraordinary manner in any one species, compared with the other species of the same genus, we may conclude that this part has undergone an extraordinary amount of modification since the period when the species branched off from the common progenitor of the genus. This period will seldom be remote in any extreme degree, as species very rarely endure for more than one geological period. An extraordinary amount of modification implies an unusually large and long-continued amount of variability, which has continually been accumulated by natural selection for the benefit of the species. But as the variability of the extraordinarily-developed part or organ has been so great and long-continued within a period not excessively remote, we might, as a general rule, expect still to find more variability in such parts than in other parts of the organisation which have remained for a much longer period nearly constant. And this, I am convinced, is the case. That the struggle between natural selection on the one hand, and the tendency to reversion and variability on the other hand, will in the {154} course of time cease; and that the most abnormally developed organs may be made constant, I can see no reason to doubt. Hence when an organ, however abnormal it may be, has been transmitted in approximately the same condition to many modified descendants, as in the case of the wing of the bat, it must have existed, according to my theory, for an immense period in nearly the same state; and thus it comes to be no more variable than any other structure. It is only in those cases in which the modification has been comparatively recent and extraordinarily great that we ought to find the _generative variability_, as it may be called, still present in a high degree. For in this case the variability will seldom as yet have been fixed by the continued selection of the individuals varying in the required manner and degree, and by the continued rejection of those tending to revert to a former and less modified condition. The principle included in these remarks may be extended. It is notorious that specific characters are more variable than generic. To explain by a simple example what is meant. If some species in a large genus of plants had blue flowers and some had red, the colour would be only a specific character, and no one would be surprised at one of the blue species varying into red, or conversely; but if all the species had blue flowers, the colour would become a generic character, and its variation would be a more unusual circumstance. I have chosen this example because an explanation is not in this case applicable, which most naturalists would advance, namely, that specific characters are more variable than generic, because they are taken from parts of less physiological importance than those commonly used for classing genera. I believe this explanation is partly, yet only indirectly, true; I shall, however, have to {155} return to this subject in our chapter on Classification. It would be almost superfluous to adduce evidence in support of the above statement, that specific characters are more variable than generic; but I have repeatedly noticed in works on natural history, that when an author has remarked with surprise that some _important_ organ or part, which is generally very constant throughout large groups of species, has _differed_ considerably in closely-allied species, that it has, also, been _variable_ in the individuals of some of the species. And this fact shows that a character, which is generally of generic value, when it sinks in value and becomes only of specific value, often becomes variable, though its physiological importance may remain the same. Something of the same kind applies to monstrosities: at least Is. Geoffroy St. Hilaire seems to entertain no doubt, that the more an organ normally differs in the different species of the same group, the more subject it is to individual anomalies. On the ordinary view of each species having been independently created, why should that part of the structure, which differs from the same part in other independently-created species of the same genus, be more variable than those parts which are closely alike in the several species? I do not see that any explanation can be given. But on the view of species being only strongly marked and fixed varieties, we might surely expect to find them still often continuing to vary in those parts of their structure which have varied within a moderately recent period, and which have thus come to differ. Or to state the case in another manner:--the points in which all the species of a genus resemble each other, and in which they differ from the species of some other genus, are called generic characters; and these characters in common I attribute to {156} inheritance from a common progenitor, for it can rarely have happened that natural selection will have modified several species, fitted to more or less widely-different habits, in exactly the same manner: and as these so-called generic characters have been inherited from a remote period, since that period when the species first branched off from their common progenitor, and subsequently have not varied or come to differ in any degree, or only in a slight degree, it is not probable that they should vary at the present day. On the other hand, the points in which species differ from other species of the same genus, are called specific characters; and as these specific characters have varied and come to differ within the period of the branching off of the species from a common progenitor, it is probable that they should still often be in some degree variable,--at least more variable than those parts of the organisation which have for a very long period remained constant. In connexion with the present subject, I will make only two other remarks. I think it will be admitted, without my entering on details, that secondary sexual characters are very variable; I think it also will be admitted that species of the same group differ from each other more widely in their secondary sexual characters, than in other parts of their organisation; compare, for instance, the amount of difference between the males of gallinaceous birds, in which secondary sexual characters are strongly displayed, with the amount of difference between their females; and the truth of this proposition will be granted. The cause of the original variability of secondary sexual characters is not manifest; but we can see why these characters should not have been rendered as constant and uniform as other parts of the organisation; for secondary sexual characters have been accumulated by sexual selection, which {157} is less rigid in its action than ordinary selection, as it does not entail death, but only gives fewer offspring to the less favoured males. Whatever the cause may be of the variability of secondary sexual characters, as they are highly variable, sexual selection will have had a wide scope for action, and may thus readily have succeeded in giving to the species of the same group a greater amount of difference in their sexual characters, than in other parts of their structure. It is a remarkable fact, that the secondary sexual differences between the two sexes of the same species are generally displayed in the very same parts of the organisation in which the different species of the same genus differ from each other. Of this fact I will give in illustration two instances, the first which happen to stand on my list; and as the differences in these cases are of a very unusual nature, the relation can hardly be accidental. The same number of joints in the tarsi is a character generally common to very large groups of beetles, but in the Engidæ, as Westwood has remarked, the number varies greatly; and the number likewise differs in the two sexes of the same species: again in fossorial hymenoptera, the manner of neuration of the wings is a character of the highest importance, because common to large groups; but in certain genera the neuration differs in the different species, and likewise in the two sexes of the same species. This relation has a clear meaning on my view of the subject: I look at all the species of the same genus as having as certainly descended from the same progenitor, as have the two sexes of any one of the species. Consequently, whatever part of the structure of the common progenitor, or of its early descendants, became variable; variations of this part would, it is highly probable, be taken advantage of by natural and sexual selection, in order to fit {158} the several species to their several places in the economy of nature, and likewise to fit the two sexes of the same species to each other, or to fit the males and females to different habits of life, or the males to struggle with other males for the possession of the females. Finally, then, I conclude that the greater variability of specific characters, or those which distinguish species from species, than of generic characters, or those which the species possess in common;--that the frequent extreme variability of any part which is developed in a species in an extraordinary manner in comparison with the same part in its congeners; and the slight degree of variability in a part, however extraordinarily it may be developed, if it be common to a whole group of species;--that the great variability of secondary sexual characters, and the great amount of difference in these same characters between closely allied species;--that secondary sexual and ordinary specific differences are generally displayed in the same parts of the organisation,--are all principles closely connected together. All being mainly due to the species of the same group having descended from a common progenitor, from whom they have inherited much in common,--to parts which have recently and largely varied being more likely still to go on varying than parts which have long been inherited and have not varied,--to natural selection having more or less completely, according to the lapse of time, overmastered the tendency to reversion and to further variability,--to sexual selection being less rigid than ordinary selection,--and to variations in the same parts having been accumulated by natural and sexual selection, and having been thus adapted for secondary sexual, and for ordinary specific purposes. {159} _Distinct species present analogous variations; and a variety of one species often assumes some of the characters of an allied species, or reverts to some of the characters of an early progenitor._--These propositions will be most readily understood by looking to our domestic races. The most distinct breeds of pigeons, in countries most widely apart, present sub-varieties with reversed feathers on the head and feathers on the feet,--characters not possessed by the aboriginal rock-pigeon; these then are analogous variations in two or more distinct races. The frequent presence of fourteen or even sixteen tail-feathers in the pouter, may be considered as a variation representing the normal structure of another race, the fantail. I presume that no one will doubt that all such analogous variations are due to the several races of the pigeon having inherited from a common parent the same constitution and tendency to variation, when acted on by similar unknown influences. In the vegetable kingdom we have a case of analogous variation, in the enlarged stems, or roots as commonly called, of the Swedish turnip and Ruta baga, plants which several botanists rank as varieties produced by cultivation from a common parent: if this be not so, the case will then be one of analogous variation in two so-called distinct species; and to these a third may be added, namely, the common turnip. According to the ordinary view of each species having been independently created, we should have to attribute this similarity in the enlarged stems of these three plants, not to the _vera causa_ of community of descent, and a consequent tendency to vary in a like manner, but to three separate yet closely related acts of creation. With pigeons, however, we have another case, namely, the occasional appearance in all the breeds, of slaty-blue birds with two black bars on the wings, a white {160} rump, a bar at the end of the tail, with the outer feathers externally edged near their bases with white. As all these marks are characteristic of the parent rock-pigeon, I presume that no one will doubt that this is a case of reversion, and not of a new yet analogous variation appearing in the several breeds. We may I think confidently come to this conclusion, because, as we have seen, these coloured marks are eminently liable to appear in the crossed offspring of two distinct and differently coloured breeds; and in this case there is nothing in the external conditions of life to cause the reappearance of the slaty-blue, with the several marks, beyond the influence of the mere act of crossing on the laws of inheritance. No doubt it is a very surprising fact that characters should reappear after having been lost for many, perhaps for hundreds of generations. But when a breed has been crossed only once by some other breed, the offspring occasionally show a tendency to revert in character to the foreign breed for many generations--some say, for a dozen or even a score of generations. After twelve generations, the proportion of blood, to use a common expression, of any one ancestor, is only 1 in 2048; and yet, as we see, it is generally believed that a tendency to reversion is retained by this very small proportion of foreign blood. In a breed which has not been crossed, but in which _both_ parents have lost some character which their progenitor possessed, the tendency, whether strong or weak, to reproduce the lost character might be, as was formerly remarked, for all that we can see to the contrary, transmitted for almost any number of generations. When a character which has been lost in a breed, reappears after a great number of generations, the most probable hypothesis is, not that the offspring suddenly takes after an ancestor some hundred generations {161} distant, but that in each successive generation there has been a tendency to reproduce the character in question, which at last, under unknown favourable conditions, gains an ascendancy. For instance, it is probable that in each generation of the barb-pigeon, which produces most rarely a blue and black-barred bird, there has been a tendency in each generation in the plumage to assume this colour. This view is hypothetical, but could be supported by some facts; and I can see no more abstract improbability in a tendency to produce any character being inherited for an endless number of generations, than in quite useless or rudimentary organs being, as we all know them to be, thus inherited. Indeed, we may sometimes observe a mere tendency to produce a rudiment inherited: for instance, in the common snapdragon (Antirrhinum) a rudiment of a fifth stamen so often appears, that this plant must have an inherited tendency to produce it. As all the species of the same genus are supposed, on my theory, to have descended from a common parent, it might be expected that they would occasionally vary in an analogous manner; so that a variety of one species would resemble in some of its characters another species; this other species being on my view only a well-marked and permanent variety. But characters thus gained would probably be of an unimportant nature, for the presence of all important characters will be governed by natural selection, in accordance with the diverse habits of the species, and will not be left to the mutual action of the conditions of life and of a similar inherited constitution. It might further be expected that the species of the same genus would occasionally exhibit reversions to lost ancestral characters. As, however, we never know the exact character of the common ancestor of a group, we could not distinguish these two {162} cases: if, for instance, we did not know that the rock-pigeon was not feather-footed or turn-crowned, we could not have told, whether these characters in our domestic breeds were reversions or only analogous variations; but we might have inferred that the blueness was a case of reversion, from the number of the markings, which are correlated with the blue tint, and which it does not appear probable would all appear together from simple variation. More especially we might have inferred this, from the blue colour and marks so often appearing when distinct breeds of diverse colours are crossed. Hence, though under nature it must generally be left doubtful, what cases are reversions to an anciently existing character, and what are new but analogous variations, yet we ought, on my theory, sometimes to find the varying offspring of a species assuming characters (either from reversion or from analogous variation) which already occur in some other members of the same group. And this undoubtedly is the case in nature. A considerable part of the difficulty in recognising a variable species in our systematic works, is due to its varieties mocking, as it were, some of the other species of the same genus. A considerable catalogue, also, could be given of forms intermediate between two other forms, which themselves must be doubtfully ranked as either varieties or species; and this shows, unless all these forms be considered as independently created species, that the one in varying has assumed some of the characters of the other, so as to produce the intermediate form. But the best evidence is afforded by parts or organs of an important and uniform nature occasionally varying so as to acquire, in some degree, the character of the same part or organ in an allied species. I have collected a long list of such cases; but {163} here, as before, I lie under a great disadvantage in not being able to give them. I can only repeat that such cases certainly do occur, and seem to me very remarkable. I will, however, give one curious and complex case, not indeed as affecting any important character, but from occurring in several species of the same genus, partly under domestication and partly under nature. It is a case apparently of reversion. The ass not rarely has very distinct transverse bars on its legs, like those on the legs of the zebra: it has been asserted that these are plainest in the foal, and from inquiries which I have made, I believe this to be true. It has also been asserted that the stripe on each shoulder is sometimes double. The shoulder-stripe is certainly very variable in length and outline. A white ass, but _not_ an albino, has been described without either spinal or shoulder stripe; and these stripes are sometimes very obscure, or actually quite lost, in dark-coloured asses. The koulan of Pallas is said to have been seen with a double shoulder-stripe. The hemionus has no shoulder-stripe; but traces of it, as stated by Mr. Blyth and others, occasionally appear: and I have been informed by Colonel Poole that the foals of this species are generally striped on the legs, and faintly on the shoulder. The quagga, though so plainly barred like a zebra over the body, is without bars on the legs; but Dr. Gray has figured one specimen with very distinct zebra-like bars on the hocks. With respect to the horse, I have collected cases in England of the spinal stripe in horses of the most distinct breeds, and of _all_ colours; transverse bars on the legs are not rare in duns, mouse-duns, and in one instance in a chestnut: a faint shoulder-stripe may sometimes be seen in duns, and I have seen a trace in a {164} bay horse. My son made a careful examination and sketch for me of a dun Belgian cart-horse with a double stripe on each shoulder and with leg-stripes; and a man, whom I can implicitly trust, has examined for me a small dun Welch pony with _three_ short parallel stripes on each shoulder. In the north-west part of India the Kattywar breed of horses is so generally striped, that, as I hear from Colonel Poole, who examined the breed for the Indian Government, a horse without stripes is not considered as purely-bred. The spine is always striped; the legs are generally barred; and the shoulder-stripe, which is sometimes double and sometimes treble, is common; the side of the face, moreover, is sometimes striped. The stripes are plainest in the foal; and sometimes quite disappear in old horses. Colonel Poole has seen both gray and bay Kattywar horses striped when first foaled. I have, also, reason to suspect, from information given me by Mr. W. W. Edwards, that with the English racehorse the spinal stripe is much commoner in the foal than in the full-grown animal. Without here entering on further details, I may state that I have collected cases of leg and shoulder stripes in horses of very different breeds, in various countries from Britain to Eastern China; and from Norway in the north to the Malay Archipelago in the south. In all parts of the world these stripes occur far oftenest in duns and mouse-duns; by the term dun a large range of colour is included, from one between brown and black to a close approach to cream-colour. I am aware that Colonel Hamilton Smith, who has written on this subject, believes that the several breeds of the horse have descended from several aboriginal species--one of which, the dun, was striped; and that the above-described appearances are all due to ancient {165} crosses with the dun stock. But I am not at all satisfied with this theory, and should be loth to apply it to breeds so distinct as the heavy Belgian cart-horse, Welch ponies, cobs, the lanky Kattywar race, &c., inhabiting the most distant parts of the world. Now let us turn to the effects of crossing the several species of the horse-genus. Rollin asserts, that the common mule from the ass and horse is particularly apt to have bars on its legs: according to Mr. Gosse, in certain parts of the United States about nine out of ten mules have striped legs. I once saw a mule with its legs so much striped that any one would at first have thought that it must have been the product of a zebra; and Mr. W. C. Martin, in his excellent treatise on the horse, has given a figure of a similar mule. In four coloured drawings, which I have seen, of hybrids between the ass and zebra, the legs were much more plainly barred than the rest of the body; and in one of them there was a double shoulder-stripe. In Lord Morton's famous hybrid from a chestnut mare and male quagga, the hybrid, and even the pure offspring subsequently produced from the mare by a black Arabian sire, were much more plainly barred across the legs than is even the pure quagga. Lastly, and this is another most remarkable case, a hybrid has been figured by Dr. Gray (and he informs me that he knows of a second case) from the ass and the hemionus; and this hybrid, though the ass seldom has stripes on his legs and the hemionus has none and has not even a shoulder-stripe, nevertheless had all four legs barred, and had three short shoulder-stripes, like those on the dun Welch pony, and even had some zebra-like stripes on the sides of its face. With respect to this last fact, I was so convinced that not even a stripe of colour appears from what would commonly be called an {166} accident, that I was led solely from the occurrence of the face-stripes on this hybrid from the ass and hemionus to ask Colonel Poole whether such face-stripes ever occur in the eminently striped Kattywar breed of horses, and was, as we have seen, answered in the affirmative. What now are we to say to these several facts? We see several very distinct species of the horse-genus becoming, by simple variation, striped on the legs like a zebra, or striped on the shoulders like an ass. In the horse we see this tendency strong whenever a dun tint appears--a tint which approaches to that of the general colouring of the other species of the genus. The appearance of the stripes is not accompanied by any change of form or by any other new character. We see this tendency to become striped most strongly displayed in hybrids from between several of the most distinct species. Now observe the case of the several breeds of pigeons: they are descended from a pigeon (including two or three sub-species or geographical races) of a bluish colour, with certain bars and other marks; and when any breed assumes by simple variation a bluish tint, these bars and other marks invariably reappear; but without any other change of form or character. When the oldest and truest breeds of various colours are crossed, we see a strong tendency for the blue tint and bars and marks to reappear in the mongrels. I have stated that the most probable hypothesis to account for the reappearance of very ancient characters, is--that there is a _tendency_ in the young of each successive generation to produce the long-lost character, and that this tendency, from unknown causes, sometimes prevails. And we have just seen that in several species of the horse-genus the stripes are either plainer or appear more commonly in the young than in the old. Call the breeds of pigeons, some of which have bred true for {167} centuries, species; and how exactly parallel is the case with that of the species of the horse-genus! For myself, I venture confidently to look back thousands on thousands of generations, and I see an animal striped like a zebra, but perhaps otherwise very differently constructed, the common parent of our domestic horse, whether or not it be descended from one or more wild stocks, of the ass, the hemionus, quagga, and zebra. He who believes that each equine species was independently created, will, I presume, assert that each species has been created with a tendency to vary, both under nature and under domestication, in this particular manner, so as often to become striped like other species of the genus; and that each has been created with a strong tendency, when crossed with species inhabiting distant quarters of the world, to produce hybrids resembling in their stripes, not their own parents, but other species of the genus. To admit this view is, as it seems to me, to reject a real for an unreal, or at least for an unknown, cause. It makes the works of God a mere mockery and deception; I would almost as soon believe with the old and ignorant cosmogonists, that fossil shells had never lived, but had been created in stone so as to mock the shells now living on the sea-shore. _Summary._--Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part differs, more or less, from the same part in the parents. But whenever we have the means of instituting a comparison, the same laws appear to have acted in producing the lesser differences between varieties of the same species, and the greater differences between species of the same genus. The external conditions of life, as {168} climate and food, &c., seem to have induced some slight modifications. Habit in producing constitutional differences, and use in strengthening and disuse in weakening and diminishing organs, seem to have been more potent in their effects. Homologous parts tend to vary in the same way, and homologous parts tend to cohere. Modifications in hard parts and in external parts sometimes affect softer and internal parts. When one part is largely developed, perhaps it tends to draw nourishment from the adjoining parts; and every part of the structure which can be saved without detriment to the individual, will be saved. Changes of structure at an early age will generally affect parts subsequently developed; and there are very many other correlations of growth, the nature of which we are utterly unable to understand. Multiple parts are variable in number and in structure, perhaps arising from such parts not having been closely specialised to any particular function, so that their modifications have not been closely checked by natural selection. It is probably from this same cause that organic beings low in the scale of nature are more variable than those which have their whole organisation more specialised, and are higher in the scale. Rudimentary organs, from being useless, will be disregarded by natural selection, and hence probably are variable. Specific characters--that is, the characters which have come to differ since the several species of the same genus branched off from a common parent--are more variable than generic characters, or those which have long been inherited, and have not differed within this same period. In these remarks we have referred to special parts or organs being still variable, because they have recently varied and thus come to differ; but we have also seen in the second Chapter that the same principle applies to the whole individual; {169} for in a district where many species of any genus are found--that is, where there has been much former variation and differentiation, or where the manufactory of new specific forms has been actively at work--there, on an average, we now find most varieties or incipient species. Secondary sexual characters are highly variable, and such characters differ much in the species of the same group. Variability in the same parts of the organisation has generally been taken advantage of in giving secondary sexual differences to the sexes of the same species, and specific differences to the several species of the same genus. Any part or organ developed to an extraordinary size or in an extraordinary manner, in comparison with the same part or organ in the allied species, must have gone through an extraordinary amount of modification since the genus arose; and thus we can understand why it should often still be variable in a much higher degree than other parts; for variation is a long-continued and slow process, and natural selection will in such cases not as yet have had time to overcome the tendency to further variability and to reversion to a less modified state. But when a species with any extraordinarily-developed organ has become the parent of many modified descendants--which on my view must be a very slow process, requiring a long lapse of time--in this case, natural selection may readily have succeeded in giving a fixed character to the organ, in however extraordinary a manner it may be developed. Species inheriting nearly the same constitution from a common parent and exposed to similar influences will naturally tend to present analogous variations, and these same species may occasionally revert to some of the characters of their ancient progenitors. Although new and important modifications may not arise from reversion and analogous {170} variation, such modifications will add to the beautiful and harmonious diversity of nature. Whatever the cause may be of each slight difference in the offspring from their parents--and a cause for each must exist--it is the steady accumulation, through natural selection, of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure, by which the innumerable beings on the face of this earth are enabled to struggle with each other, and the best adapted to survive. * * * * * {171} CHAPTER VI. DIFFICULTIES ON THEORY. Difficulties on the theory of descent with modification--Transitions--Absence or rarity of transitional varieties--Transitions in habits of life--Diversified habits in the same species--Species with habits widely different from those of their allies--Organs of extreme perfection--Means of transition--Cases of difficulty--Natura non facit saltum--Organs of small importance--Organs not in all cases absolutely perfect--The law of Unity of Type and of the Conditions of Existence embraced by the theory of Natural Selection. Long before having arrived at this part of my work, a crowd of difficulties will have occurred to the reader. Some of them are so grave that to this day I can never reflect on them without being staggered; but, to the best of my judgment, the greater number are only apparent, and those that are real are not, I think, fatal to my theory. These difficulties and objections may be classed under the following heads:--Firstly, why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion instead of the species being, as we see them, well defined? Secondly, is it possible that an animal having, for instance, the structure and habits of a bat, could have been formed by the modification of some animal with wholly different habits? Can we believe that natural selection could produce, on the one hand, organs of trifling importance, such as the tail of a giraffe, which serves as a fly-flapper, and, on the other hand, organs of {172} such wonderful structure, as the eye, of which we hardly as yet fully understand the inimitable perfection? Thirdly, can instincts be acquired and modified through natural selection? What shall we say to so marvellous an instinct as that which leads the bee to make cells, which has practically anticipated the discoveries of profound mathematicians? Fourthly, how can we account for species, when crossed, being sterile and producing sterile offspring, whereas, when varieties are crossed, their fertility is unimpaired? The two first heads shall be here discussed--Instinct and Hybridism in separate chapters. _On the absence or rarity of transitional varieties._--As natural selection acts solely by the preservation of profitable modifications, each new form will tend in a fully-stocked country to take the place of, and finally to exterminate, its own less improved parent or other less-favoured forms with which it comes into competition. Thus extinction and natural selection will, as we have seen, go hand in hand. Hence, if we look at each species as descended from some other unknown form, both the parent and all the transitional varieties will generally have been exterminated by the very process of formation and perfection of the new form. But, as by this theory innumerable transitional forms must have existed, why do we not find them embedded in countless numbers in the crust of the earth? It will be much more convenient to discuss this question in the chapter on the Imperfection of the geological record; and I will here only state that I believe the answer mainly lies in the record being incomparably less perfect than is generally supposed; the imperfection of the record being chiefly due to organic beings not inhabiting {173} profound depths of the sea, and to their remains being embedded and preserved to a future age only in masses of sediment sufficiently thick and extensive to withstand an enormous amount of future degradation; and such fossiliferous masses can be accumulated only where much sediment is deposited on the shallow bed of the sea, whilst it slowly subsides. These contingencies will concur only rarely, and after enormously long intervals. Whilst the bed of the sea is stationary or is rising, or when very little sediment is being deposited, there will be blanks in our geological history. The crust of the earth is a vast museum; but the natural collections have been made only at intervals of time immensely remote. But it may be urged that when several closely-allied species inhabit the same territory we surely ought to find at the present time many transitional forms. Let us take a simple case: in travelling from north to south over a continent, we generally meet at successive intervals with closely allied or representative species, evidently filling nearly the same place in the natural economy of the land. These representative species often meet and interlock; and as the one becomes rarer and rarer, the other becomes more and more frequent, till the one replaces the other. But if we compare these species where they intermingle, they are generally as absolutely distinct from each other in every detail of structure as are specimens taken from the metropolis inhabited by each. By my theory these allied species have descended from a common parent; and during the process of modification, each has become adapted to the conditions of life of its own region, and has supplanted and exterminated its original parent and all the transitional varieties between its past and present states. Hence we ought not to expect at the {174} present time to meet with numerous transitional varieties in each region, though they must have existed there, and may be embedded there in a fossil condition. But in the intermediate region, having intermediate conditions of life, why do we not now find closely-linking intermediate varieties? This difficulty for a long time quite confounded me. But I think it can be in large part explained. In the first place we should be extremely cautious in inferring, because an area is now continuous, that it has been continuous during a long period. Geology would lead us to believe that almost every continent has been broken up into islands even during the later tertiary periods; and in such islands distinct species might have been separately formed without the possibility of intermediate varieties existing in the intermediate zones. By changes in the form of the land and of climate, marine areas now continuous must often have existed within recent times in a far less continuous and uniform condition than at present. But I will pass over this way of escaping from the difficulty; for I believe that many perfectly defined species have been formed on strictly continuous areas; though I do not doubt that the formerly broken condition of areas now continuous has played an important part in the formation of new species, more especially with freely-crossing and wandering animals. In looking at species as they are now distributed over a wide area, we generally find them tolerably numerous over a large territory, then becoming somewhat abruptly rarer and rarer on the confines, and finally disappearing. Hence the neutral territory between two representative species is generally narrow in comparison with the territory proper to each. We see the same fact in ascending mountains, and sometimes {175} it is quite remarkable how abruptly, as Alph. de Candolle has observed, a common alpine species disappears. The same fact has been noticed by E. Forbes in sounding the depths of the sea with the dredge. To those who look at climate and the physical conditions of life as the all-important elements of distribution, these facts ought to cause surprise, as climate and height or depth graduate away insensibly. But when we bear in mind that almost every species, even in its metropolis, would increase immensely in numbers, were it not for other competing species; that nearly all either prey on or serve as prey for others; in short, that each organic being is either directly or indirectly related in the most important manner to other organic beings, we must see that the range of the inhabitants of any country by no means exclusively depends on insensibly changing physical conditions, but in large part on the presence of other species, on which it depends, or by which it is destroyed, or with which it comes into competition; and as these species are already defined objects (however they may have become so), not blending one into another by insensible gradations, the range of any one species, depending as it does on the range of others, will tend to be sharply defined. Moreover, each species on the confines of its range, where it exists in lessened numbers, will, during fluctuations in the number of its enemies or of its prey, or in the seasons, be extremely liable to utter extermination; and thus its geographical range will come to be still more sharply defined. If I am right in believing that allied or representative species, when inhabiting a continuous area, are generally so distributed that each has a wide range, with a comparatively narrow neutral territory between them, in which they become rather suddenly rarer and rarer; then, as varieties do not essentially differ from species, {176} the same rule will probably apply to both; and if we in imagination adapt a varying species to a very large area, we shall have to adapt two varieties to two large areas, and a third variety to a narrow intermediate zone. The intermediate variety, consequently, will exist in lesser numbers from inhabiting a narrow and lesser area; and practically, as far as I can make out, this rule holds good with varieties in a state of nature. I have met with striking instances of the rule in the case of varieties intermediate between well-marked varieties in the genus Balanus. And it would appear from information given me by Mr. Watson, Dr. Asa Gray, and Mr. Wollaston, that generally when varieties intermediate between two other forms occur, they are much rarer numerically than the forms which they connect. Now, if we may trust these facts and inferences, and therefore conclude that varieties linking two other varieties together have generally existed in lesser numbers than the forms which they connect, then, I think, we can understand why intermediate varieties should not endure for very long periods;--why as a general rule they should be exterminated and disappear, sooner than the forms which they originally linked together. For any form existing in lesser numbers would, as already remarked, run a greater chance of being exterminated than one existing in large numbers; and in this particular case the intermediate form would be eminently liable to the inroads of closely allied forms existing on both sides of it. But a far more important consideration, as I believe, is that, during the process of further modification, by which two varieties are supposed on my theory to be converted and perfected into two distinct species, the two which exist in larger numbers from inhabiting larger areas, will have a great advantage over the intermediate variety, which exists {177} in smaller numbers in a narrow and intermediate zone. For forms existing in larger numbers will always have a better chance, within any given period, of presenting further favourable variations for natural selection to seize on, than will the rarer forms which exist in lesser numbers. Hence, the more common forms, in the race for life, will tend to beat and supplant the less common forms, for these will be more slowly modified and improved. It is the same principle which, as I believe, accounts for the common species in each country, as shown in the second chapter, presenting on an average a greater number of well-marked varieties than do the rarer species. I may illustrate what I mean by supposing three varieties of sheep to be kept, one adapted to an extensive mountainous region; a second to a comparatively narrow, hilly tract; and a third to wide plains at the base; and that the inhabitants are all trying with equal steadiness and skill to improve their stocks by selection; the chances in this case will be strongly in favour of the great holders on the mountains or on the plains improving their breeds more quickly than the small holders on the intermediate narrow, hilly tract; and consequently the improved mountain or plain breed will soon take the place of the less improved hill breed; and thus the two breeds, which originally existed in greater numbers, will come into close contact with each other, without the interposition of the supplanted, intermediate hill-variety. To sum up, I believe that species come to be tolerably well-defined objects, and do not at any one period present an inextricable chaos of varying and intermediate links: firstly, because new varieties are very slowly formed, for variation is a very slow process, and natural selection can do nothing until favourable {178} variations chance to occur, and until a place in the natural polity of the country can be better filled by some modification of some one or more of its inhabitants. And such new places will depend on slow changes of climate, or on the occasional immigration of new inhabitants, and, probably, in a still more important degree, on some of the old inhabitants becoming slowly modified, with the new forms thus produced and the old ones acting and reacting on each other. So that, in any one region and at any one time, we ought only to see a few species presenting slight modifications of structure in some degree permanent; and this assuredly we do see. Secondly, areas now continuous must often have existed within the recent period in isolated portions, in which many forms, more especially amongst the classes which unite for each birth and wander much, may have separately been rendered sufficiently distinct to rank as representative species. In this case, intermediate varieties between the several representative species and their common parent, must formerly have existed in each broken portion of the land, but these links will have been supplanted and exterminated during the process of natural selection, so that they will no longer exist in a living state. Thirdly, when two or more varieties have been formed in different portions of a strictly continuous area, intermediate varieties will, it is probable, at first have been formed in the intermediate zones, but they will generally have had a short duration. For these intermediate varieties will, from reasons already assigned (namely from what we know of the actual distribution of closely allied or representative species, and likewise of acknowledged varieties), exist in the intermediate zones in lesser numbers than the varieties which they {179} tend to connect. From this cause alone the intermediate varieties will be liable to accidental extermination; and during the process of further modification through natural selection, they will almost certainly be beaten and supplanted by the forms which they connect; for these from existing in greater numbers will, in the aggregate, present more variation, and thus be further improved through natural selection and gain further advantages. Lastly, looking not to any one time, but to all time, if my theory be true, numberless intermediate varieties, linking most closely all the species of the same group together, must assuredly have existed; but the very process of natural selection constantly tends, as has been so often remarked, to exterminate the parent-forms and the intermediate links. Consequently evidence of their former existence could be found only amongst fossil remains, which are preserved, as we shall in a future chapter attempt to show, in an extremely imperfect and intermittent record. _On the origin and transitions of organic beings with peculiar habits and structure._--It has been asked by the opponents of such views as I hold, how, for instance, a land carnivorous animal could have been converted into one with aquatic habits; for how could the animal in its transitional state have subsisted? It would be easy to show that within the same group carnivorous animals exist having every intermediate grade between truly aquatic and strictly terrestrial habits; and as each exists by a struggle for life, it is clear that each is well adapted in its habits to its place in nature. Look at the Mustela vison of North America, which has webbed feet and which resembles an otter in its fur, short legs, and form of tail; during summer this animal {180} dives for and preys on fish, but during the long winter it leaves the frozen waters, and preys like other polecats on mice and land animals. If a different case had been taken, and it had been asked how an insectivorous quadruped could possibly have been converted into a flying bat, the question would have been far more difficult, and I could have given no answer. Yet I think such difficulties have very little weight. Here, as on other occasions, I lie under a heavy disadvantage, for out of the many striking cases which I have collected, I can give only one or two instances of transitional habits and structures in closely allied species of the same genus; and of diversified habits, either constant or occasional, in the same species. And it seems to me that nothing less than a long list of such cases is sufficient to lessen the difficulty in any particular case like that of the bat. Look at the family of squirrels; here we have the finest gradation from animals with their tails only slightly flattened, and from others, as Sir J. Richardson has remarked, with the posterior part of their bodies rather wide and with the skin on their flanks rather full, to the so-called flying squirrels; and flying squirrels have their limbs and even the base of the tail united by a broad expanse of skin, which serves as a parachute and allows them to glide through the air to an astonishing distance from tree to tree. We cannot doubt that each structure is of use to each kind of squirrel in its own country, by enabling it to escape birds or beasts of prey, or to collect food more quickly, or, as there is reason to believe, by lessening the danger from occasional falls. But it does not follow from this fact that the structure of each squirrel is the best that it is possible to conceive under all natural conditions. Let the climate and vegetation change, let other competing {181} rodents or new beasts of prey immigrate, or old ones become modified, and all analogy would lead us to believe that some at least of the squirrels would decrease in numbers or become exterminated, unless they also became modified and improved in structure in a corresponding manner. Therefore, I can see no difficulty, more especially under changing conditions of life, in the continued preservation of individuals with fuller and fuller flank-membranes, each modification being useful, each being propagated, until by the accumulated effects of this process of natural selection, a perfect so-called flying squirrel was produced. Now look at the Galeopithecus or flying lemur, which formerly was falsely ranked amongst bats. It has an extremely wide flank-membrane, stretching from the corners of the jaw to the tail, and including the limbs and the elongated fingers: the flank-membrane is, also, furnished with an extensor muscle. Although no graduated links of structure, fitted for gliding through the air, now connect the Galeopithecus with the other Lemuridæ, yet I see no difficulty in supposing that such links formerly existed, and that each had been formed by the same steps as in the case of the less perfectly gliding squirrels; and that each grade of structure was useful to its possessor. Nor can I see any insuperable difficulty in further believing it possible that the membrane-connected fingers and forearm of the Galeopithecus might be greatly lengthened by natural selection; and this, as far as the organs of flight are concerned, would convert it into a bat. In bats which have the wing-membrane extended from the top of the shoulder to the tail, including the hind-legs, we perhaps see traces of an apparatus originally constructed for gliding through the air rather than for flight. {182} If about a dozen genera of birds had become extinct or were unknown, who would have ventured to have surmised that birds might have existed which used their wings solely as flappers, like the logger-headed duck (Micropterus of Eyton); as fins in the water and front legs on the land, like the penguin; as sails, like the ostrich; and functionally for no purpose, like the Apteryx. Yet the structure of each of these birds is good for it, under the conditions of life to which it is exposed, for each has to live by a struggle; but it is not necessarily the best possible under all possible conditions. It must not be inferred from these remarks that any of the grades of wing-structure here alluded to, which perhaps may all have resulted from disuse, indicate the natural steps by which birds have acquired their perfect power of flight; but they serve, at least, to show what diversified means of transition are possible. Seeing that a few members of such water-breathing classes as the Crustacea and Mollusca are adapted to live on the land; and seeing that we have flying birds and mammals, flying insects of the most diversified types, and formerly had flying reptiles, it is conceivable that flying-fish, which now glide far through the air, slightly rising and turning by the aid of their fluttering fins, might have been modified into perfectly winged animals. If this had been effected, who would have ever imagined that in an early transitional state they had been inhabitants of the open ocean, and had used their incipient organs of flight exclusively, as far as we know, to escape being devoured by other fish? When we see any structure highly perfected for any particular habit, as the wings of a bird for flight, we should bear in mind that animals displaying early {183} transitional grades of the structure will seldom continue to exist to the present day, for they will have been supplanted by the very process of perfection through natural selection. Furthermore, we may conclude that transitional grades between structures fitted for very different habits of life will rarely have been developed at an early period in great numbers and under many subordinate forms. Thus, to return to our imaginary illustration of the flying-fish, it does not seem probable that fishes capable of true flight would have been developed under many subordinate forms, for taking prey of many kinds in many ways, on the land and in the water, until their organs of flight had come to a high stage of perfection, so as to have given them a decided advantage over other animals in the battle for life. Hence the chance of discovering species with transitional grades of structure in a fossil condition will always be less, from their having existed in lesser numbers, than in the case of species with fully developed structures. I will now give two or three instances of diversified and of changed habits in the individuals of the same species. When either case occurs, it would be easy for natural selection to fit the animal, by some modification of its structure, for its changed habits, or exclusively for one of its several different habits. But it is difficult to tell, and immaterial for us, whether habits generally change first and structure afterwards; or whether slight modifications of structure lead to changed habits; both probably often change almost simultaneously. Of cases of changed habits it will suffice merely to allude to that of the many British insects which now feed on exotic plants, or exclusively on artificial substances. Of diversified habits innumerable instances could be given: I have often watched a tyrant flycatcher (Saurophagus sulphuratus) in South America, hovering over one spot {184} and then proceeding to another, like a kestrel, and at other times standing stationary on the margin of water, and then dashing like a kingfisher at a fish. In our own country the larger titmouse (Parus major) may be seen climbing branches, almost like a creeper; it often, like a shrike, kills small birds by blows on the head; and I have many times seen and heard it hammering the seeds of the yew on a branch, and thus breaking them like a nuthatch. In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching, almost like a whale, insects in the water. As we sometimes see individuals of a species following habits widely different from those of their own species and of the other species of the same genus, we might expect, on my theory, that such individuals would occasionally have given rise to new species, having anomalous habits, and with their structure either slightly or considerably modified from that of their proper type. And such instances do occur in nature. Can a more striking instance of adaptation be given than that of a woodpecker for climbing trees and for seizing insects in the chinks of the bark? Yet in North America there are woodpeckers which feed largely on fruit, and others with elongated wings which chase insects on the wing; and on the plains of La Plata, where not a tree grows, there is a woodpecker, which in every essential part of its organisation, even in its colouring, in the harsh tone of its voice, and undulatory flight, told me plainly of its close blood-relationship to our common species; yet it is a woodpecker which never climbs a tree! Petrels are the most aërial and oceanic of birds, yet in the quiet Sounds of Tierra del Fuego, the Puffinuria berardi, in its general habits, in its astonishing power of diving, its manner of swimming, and of flying when {185} unwillingly it takes flight, would be mistaken by any one for an auk or grebe; nevertheless, it is essentially a petrel, but with many parts of its organisation profoundly modified. On the other hand, the acutest observer by examining the dead body of the water-ouzel would never have suspected its sub-aquatic habits; yet this anomalous member of the strictly terrestrial thrush family wholly subsists by diving,--grasping the stones with its feet and using its wings under water. He who believes that each being has been created as we now see it, must occasionally have felt surprise when he has met with an animal having habits and structure not at all in agreement. What can be plainer than that the webbed feet of ducks and geese are formed for swimming? yet there are upland geese with webbed feet which rarely or never go near the water; and no one except Audubon has seen the frigate-bird, which has all its four toes webbed, alight on the surface of the sea. On the other hand grebes and coots are eminently aquatic, although their toes are only bordered by membrane. What seems plainer than that the long toes of grallatores are formed for walking over swamps and floating plants, yet the water-hen is nearly as aquatic as the coot; and the landrail nearly as terrestrial as the quail or partridge. In such cases, and many others could be given, habits have changed without a corresponding change of structure. The webbed feet of the upland goose may be said to have become rudimentary in function, though not in structure. In the frigate-bird, the deeply-scooped membrane between the toes shows that structure has begun to change. He who believes in separate and innumerable acts of creation will say, that in these cases it has pleased the Creator to cause a being of one type to take the place of one of another type; but this seems to me only {186} restating the fact in dignified language. He who believes in the struggle for existence and in the principle of natural selection, will acknowledge that every organic being is constantly endeavouring to increase in numbers; and that if any one being vary ever so little, either in habits or structure, and thus gain an advantage over some other inhabitant of the country, it will seize on the place of that inhabitant, however different it may be from its own place. Hence it will cause him no surprise that there should be geese and frigate-birds with webbed feet, living on the dry land or most rarely alighting on the water; that there should be long-toed corncrakes living in meadows instead of in swamps; that there should be woodpeckers where not a tree grows; that there should be diving thrushes, and petrels with the habits of auks. _Organs of extreme perfection and complication._--To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. How a nerve comes to be sensitive to {187} light, hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound. In looking for the gradations by which an organ in any species has been perfected, we ought to look exclusively to its lineal ancestors; but this is scarcely ever possible, and we are forced in each case to look to species of the same group, that is to the collateral descendants from the same original parent-form, in order to see what gradations are possible, and for the chance of some gradations having been transmitted from the earlier stages of descent, in an unaltered or little altered condition. Amongst existing Vertebrata, we find but a small amount of gradation in the structure of the eye, and from fossil species we can learn nothing on this head. In this great class we should probably have to descend far beneath the lowest known fossiliferous stratum to discover the earlier stages, by which the eye has been perfected. In the Articulata we can commence a series with an optic nerve merely coated with pigment, and without any other mechanism; and from this low stage, numerous gradations of structure, branching off in two fundamentally different lines, can be shown to exist, until we reach a moderately high stage of perfection. In certain crustaceans, for instance, there is a double cornea, the inner one divided into facets, within each of which there is a lens-shaped swelling. In other crustaceans the transparent cones which are coated by pigment, and which properly act only by excluding lateral pencils of light, are convex at their upper ends and must act by convergence; and at their lower ends there seems to be an imperfect vitreous substance. {188} With these facts, here far too briefly and imperfectly given, which show that there is much graduated diversity in the eyes of living crustaceans, and bearing in mind how small the number of living animals is in proportion to those which have become extinct, I can see no very great difficulty (not more than in the case of many other structures) in believing that natural selection has converted the simple apparatus of an optic nerve merely coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the great Articulate class. He who will go thus far, if he find on finishing this treatise that large bodies of facts, otherwise inexplicable, can be explained by the theory of descent, ought not to hesitate to go further, and to admit that a structure even as perfect as the eye of an eagle might be formed by natural selection, although in this case he does not know any of the transitional grades. His reason ought to conquer his imagination; though I have felt the difficulty far too keenly to be surprised at any degree of hesitation in extending the principle of natural selection to such startling lengths. It is scarcely possible to avoid comparing the eye to a telescope. We know that this instrument has been perfected by the long-continued efforts of the highest human intellects; and we naturally infer that the eye has been formed by a somewhat analogous process. But may not this inference be presumptuous? Have we any right to assume that the Creator works by intellectual powers like those of man? If we must compare the eye to an optical instrument, we ought in imagination to take a thick layer of transparent tissue, with a nerve sensitive to light beneath, and then suppose every part of this layer to be continually changing {189} slowly in density, so as to separate into layers of different densities and thicknesses, placed at different distances from each other, and with the surfaces of each layer slowly changing in form. Further we must suppose that there is a power always intently watching each slight accidental alteration in the transparent layers; and carefully selecting each alteration which, under varied circumstances, may in any way, or in any degree, tend to produce a distincter image. We must suppose each new state of the instrument to be multiplied by the million; and each to be preserved till a better be produced, and then the old ones to be destroyed. In living bodies, variation will cause the slight alterations, generation will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement. Let this process go on for millions on millions of years; and during each year on millions of individuals of many kinds; and may we not believe that a living optical instrument might thus be formed as superior to one of glass, as the works of the Creator are to those of man? If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case. No doubt many organs exist of which we do not know the transitional grades, more especially if we look to much-isolated species, round which, according to my theory, there has been much extinction. Or again, if we look to an organ common to all the members of a large class, for in this latter case the organ must have been first formed at an extremely remote period, since which all the many members of the class have been developed; and in order to discover the early transitional grades through which the organ has {190} passed, we should have to look to very ancient ancestral forms, long since become extinct. We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. Numerous cases could be given amongst the lower animals of the same organ performing at the same time wholly distinct functions; thus the alimentary canal respires, digests, and excretes in the larva of the dragon-fly and in the fish Cobites. In the Hydra, the animal may be turned inside out, and the exterior surface will then digest and the stomach respire. In such cases natural selection might easily specialise, if any advantage were thus gained, a part or organ, which had performed two functions, for one function alone, and thus wholly change its nature by insensible steps. Two distinct organs sometimes perform simultaneously the same function in the same individual; to give one instance, there are fish with gills or branchiæ that breathe the air dissolved in the water, at the same time that they breathe free air in their swimbladders, this latter organ having a ductus pneumaticus for its supply, and being divided by highly vascular partitions. In these cases one of the two organs might with ease be modified and perfected so as to perform all the work by itself, being aided during the process of modification by the other organ; and then this other organ might be modified for some other and quite distinct purpose, or be quite obliterated. The illustration of the swimbladder in fishes is a good one, because it shows us clearly the highly important fact that an organ originally constructed for one purpose, namely flotation, may be converted into one for a wholly different purpose, namely respiration. The swimbladder has, also, been worked in as an accessory to the auditory organs of certain fish, or, for I do not know {191} which view is now generally held, a part of the auditory apparatus has been worked in as a complement to the swimbladder. All physiologists admit that the swimbladder is homologous, or "ideally similar" in position and structure with the lungs of the higher vertebrate animals: hence there seems to me to be no great difficulty in believing that natural selection has actually converted a swimbladder into a lung, or organ used exclusively for respiration. I can, indeed, hardly doubt that all vertebrate animals having true lungs have descended by ordinary generation from an ancient prototype, of which we know nothing, furnished with a floating apparatus or swimbladder. We can thus, as I infer from Professor Owen's interesting description of these parts, understand the strange fact that every particle of food and drink which we swallow has to pass over the orifice of the trachea, with some risk of falling into the lungs, notwithstanding the beautiful contrivance by which the glottis is closed. In the higher Vertebrata the branchiæ have wholly disappeared--the slits on the sides of the neck and the loop-like course of the arteries still marking in the embryo their former position. But it is conceivable that the now utterly lost branchiæ might have been gradually worked in by natural selection for some quite distinct purpose: in the same manner as, on the view entertained by some naturalists that the branchiæ and dorsal scales of Annelids are homologous with the wings and wing-covers of insects, it is probable that organs which at a very ancient period served for respiration have been actually converted into organs of flight. In considering transitions of organs, it is so important to bear in mind the probability of conversion from one function to another, that I will give one more instance. Pedunculated cirripedes have two minute folds of skin, {192} called by me the ovigerous frena, which serve, through the means of a sticky secretion, to retain the eggs until they are hatched within the sack. These cirripedes have no branchiæ, the whole surface of the body and sack, including the small frena, serving for respiration. The Balanidæ or sessile cirripedes, on the other hand, have no ovigerous frena, the eggs lying loose at the bottom of the sack, in the well-enclosed shell; but they have large folded branchiæ. Now I think no one will dispute that the ovigerous frena in the one family are strictly homologous with the branchiæ of the other family; indeed, they graduate into each other. Therefore I do not doubt that little folds of skin, which originally served as ovigerous frena, but which, likewise, very slightly aided the act of respiration, have been gradually converted by natural selection into branchiæ, simply through an increase in their size and the obliteration of their adhesive glands. If all pedunculated cirripedes had become extinct, and they have already suffered far more extinction than have sessile cirripedes, who would ever have imagined that the branchiæ in this latter family had originally existed as organs for preventing the ova from being washed out of the sack? Although we must be extremely cautious in concluding that any organ could not possibly have been produced by successive transitional gradations, yet, undoubtedly, grave cases of difficulty occur, some of which will be discussed in my future work. One of the gravest is that of neuter insects, which are often very differently constructed from either the males or fertile females; but this case will be treated of in the next chapter. The electric organs of fishes offer another case of special difficulty; it is impossible to conceive by what steps these wondrous organs have been produced; but, as Owen and others have remarked, {193} their intimate structure closely resembles that of common muscle; and as it has lately been shown that Rays have an organ closely analogous to the electric apparatus, and yet do not, as Matteucci asserts, discharge any electricity, we must own that we are far too ignorant to argue that no transition of any kind is possible. The electric organs offer another and even more serious difficulty; for they occur in only about a dozen fishes, of which several are widely remote in their affinities. Generally when the same organ appears in several members of the same class, especially if in members having very different habits of life, we may attribute its presence to inheritance from a common ancestor; and its absence in some of the members to its loss through disuse or natural selection. But if the electric organs had been inherited from one ancient progenitor thus provided, we might have expected that all electric fishes would have been specially related to each other. Nor does geology at all lead to the belief that formerly most fishes had electric organs, which most of their modified descendants have lost. The presence of luminous organs in a few insects, belonging to different families and orders, offers a parallel case of difficulty. Other cases could be given; for instance in plants, the very curious contrivance of a mass of pollen-grains, borne on a foot-stalk with a sticky gland at the end, is the same in Orchis and Asclepias,--genera almost as remote as possible amongst flowering plants. In all these cases of two very distinct species furnished with apparently the same anomalous organ, it should be observed that, although the general appearance and function of the organ may be the same, yet some fundamental difference can generally be detected. I am inclined to believe that in nearly the same way as two men have sometimes independently hit on {194} the very same invention, so natural selection, working for the good of each being and taking advantage of analogous variations, has sometimes modified in very nearly the same manner two parts in two organic beings, which beings owe but little of their structure in common to inheritance from the same ancestor. Although in many cases it is most difficult to conjecture by what transitions organs could have arrived at their present state; yet, considering that the proportion of living and known forms to the extinct and unknown is very small, I have been astonished how rarely an organ can be named, towards which no transitional grade is known to lead. The truth of this remark is indeed shown by that old but somewhat exaggerated canon in natural history of "Natura non facit saltum." We meet with this admission in the writings of almost every experienced naturalist; or, as Milne Edwards has well expressed it, Nature is prodigal in variety, but niggard in innovation. Why, on the theory of Creation, should this be so? Why should all the parts and organs of many independent beings, each supposed to have been separately created for its proper place in nature, be so commonly linked together by graduated steps? Why should not Nature have taken a leap from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection can act only by taking advantage of slight successive variations; she can never take a leap, but must advance by the shortest and slowest steps. _Organs of little apparent importance._--As natural selection acts by life and death,--by the preservation of individuals with any favourable variation, and by the destruction of those with any unfavourable deviation of structure,--I have sometimes felt much difficulty in {195} understanding the origin of simple parts, of which the importance does not seem sufficient to cause the preservation of successively varying individuals. I have sometimes felt as much difficulty, though of a very different kind, on this head, as in the case of an organ as perfect and complex as the eye. In the first place, we are much too ignorant in regard to the whole economy of any one organic being, to say what slight modifications would be of importance or not. In a former chapter I have given instances of most trifling characters, such as the down on fruit and the colour of its flesh, which, from determining the attacks of insects or from being correlated with constitutional differences, might assuredly be acted on by natural selection. The tail of the giraffe looks like an artificially constructed fly-flapper; and it seems at first incredible that this could have been adapted for its present purpose by successive slight modifications, each better and better, for so trifling an object as driving away flies; yet we should pause before being too positive even in this case, for we know that the distribution and existence of cattle and other animals in South America absolutely depends on their power of resisting the attacks of insects: so that individuals which could by any means defend themselves from these small enemies, would be able to range into new pastures and thus gain a great advantage. It is not that the larger quadrupeds are actually destroyed (except in some rare cases) by flies, but they are incessantly harassed and their strength reduced, so that they are more subject to disease, or not so well enabled in a coming dearth to search for food, or to escape from beasts of prey. Organs now of trifling importance have probably in some cases been of high importance to an early progenitor, and, after having been slowly perfected at a {196} former period, have been transmitted in nearly the same state, although now become of very slight use; and any actually injurious deviations in their structure will always have been checked by natural selection. Seeing how important an organ of locomotion the tail is in most aquatic animals, its general presence and use for many purposes in so many land animals, which in their lungs or modified swimbladders betray their aquatic origin, may perhaps be thus accounted for. A well-developed tail having been formed in an aquatic animal, it might subsequently come to be worked in for all sorts of purposes, as a fly-flapper, an organ of prehension, or as an aid in turning, as with the dog, though the aid must be slight, for the hare, with hardly any tail, can double quickly enough. In the second place, we may sometimes attribute importance to characters which are really of very little importance, and which have originated from quite secondary causes, independently of natural selection. We should remember that climate, food, &c., probably have some little direct influence on the organisation; that characters reappear from the law of reversion; that correlation of growth will have had a most important influence in modifying various structures; and finally, that sexual selection will often have largely modified the external characters of animals having a will, to give one male an advantage in fighting with another or in charming the females. Moreover when a modification of structure has primarily arisen from the above or other unknown causes, it may at first have been of no advantage to the species, but may subsequently have been taken advantage of by the descendants of the species under new conditions of life and with newly acquired habits. To give a few instances to illustrate these latter {197} remarks. If green woodpeckers alone had existed, and we did not know that there were many black and pied kinds, I dare say that we should have thought that the green colour was a beautiful adaptation to hide this tree-frequenting bird from its enemies; and consequently that it was a character of importance and might have been acquired through natural selection; as it is, I have no doubt that the colour is due to some quite distinct cause, probably to sexual selection. A trailing bamboo in the Malay Archipelago climbs the loftiest trees by the aid of exquisitely constructed hooks clustered around the ends of the branches, and this contrivance, no doubt, is of the highest service to the plant; but as we see nearly similar hooks on many trees which are not climbers, the hooks on the bamboo may have arisen from unknown laws of growth, and have been subsequently taken advantage of by the plant undergoing further modification and becoming a climber. The naked skin on the head of a vulture is generally looked at as a direct adaptation for wallowing in putridity; and so it may be, or it may possibly be due to the direct action of putrid matter; but we should be very cautious in drawing any such inference, when we see that the skin on the head of the clean-feeding male turkey is likewise naked. The sutures in the skulls of young mammals have been advanced as a beautiful adaptation for aiding parturition, and no doubt they facilitate, or may be indispensable for this act; but as sutures occur in the skulls of young birds and reptiles, which have only to escape from a broken egg, we may infer that this structure has arisen from the laws of growth, and has been taken advantage of in the parturition of the higher animals. We are profoundly ignorant of the causes producing slight and unimportant variations; and we are {198} immediately made conscious of this by reflecting on the differences in the breeds of our domesticated animals in different countries,--more especially in the less civilised countries where there has been but little artificial selection. Careful observers are convinced that a damp climate affects the growth of the hair, and that with the hair the horns are correlated. Mountain breeds always differ from lowland breeds; and a mountainous country would probably affect the hind limbs from exercising them more, and possibly even the form of the pelvis; and then by the law of homologous variation, the front limbs and even the head would probably be affected. The shape, also, of the pelvis might affect by pressure the shape of the head of the young in the womb. The laborious breathing necessary in high regions would, we have some reason to believe, increase the size of the chest; and again correlation would come into play. Animals kept by savages in different countries often have to struggle for their own subsistence, and would be exposed to a certain extent to natural selection, and individuals with slightly different constitutions would succeed best under different climates; and there is reason to believe that constitution and colour are correlated. A good observer, also, states that in cattle susceptibility to the attacks of flies is correlated with colour, as is the liability to be poisoned by certain plants; so that colour would be thus subjected to the action of natural selection. But we are far too ignorant to speculate on the relative importance of the several known and unknown laws of variation; and I have here alluded to them only to show that, if we are unable to account for the characteristic differences of our domestic breeds, which nevertheless we generally admit to have arisen through ordinary generation, we ought not to lay too much stress on our ignorance of the precise cause {199} of the slight analogous differences between species. I might have adduced for this same purpose the differences between the races of man, which are so strongly marked; I may add that some little light can apparently be thrown on the origin of these differences, chiefly through sexual selection of a particular kind, but without here entering on copious details my reasoning would appear frivolous. The foregoing remarks lead me to say a few words on the protest lately made by some naturalists, against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that very many structures have been created for beauty in the eyes of man, or for mere variety. This doctrine, if true, would be absolutely fatal to my theory. Yet I fully admit that many structures are of no direct use to their possessors. Physical conditions probably have had some little effect on structure, quite independently of any good thus gained. Correlation of growth has no doubt played a most important part, and a useful modification of one part will often have entailed on other parts diversified changes of no direct use. So again characters which formerly were useful, or which formerly had arisen from correlation of growth, or from other unknown cause, may reappear from the law of reversion, though now of no direct use. The effects of sexual selection, when displayed in beauty to charm the females, can be called useful only in rather a forced sense. But by far the most important consideration is that the chief part of the organisation of every being is simply due to inheritance; and consequently, though each being assuredly is well fitted for its place in nature, many structures now have no direct relation to the habits of life of each species. Thus, we can hardly believe that the webbed feet of the upland {200} goose or of the frigate-bird are of special use to these birds; we cannot believe that the same bones in the arm of the monkey, in the fore-leg of the horse, in the wing of the bat, and in the nipper of the seal, are of special use to these animals. We may safely attribute these structures to inheritance. But to the progenitor of the upland goose and of the frigate-bird, webbed feet no doubt were as useful as they now are to the most aquatic of existing birds. So we may believe that the progenitor of the seal had not a nipper, but a foot with five toes fitted for walking or grasping; and we may further venture to believe that the several bones in the limbs of the monkey, horse, and bat, which have been inherited from a common progenitor, were formerly of more special use to that progenitor, or its progenitors, than they now are to these animals having such widely diversified habits. Therefore we may infer that these several bones might have been acquired through natural selection, subjected formerly, as now, to the several laws of inheritance, reversion, correlation of growth, &c. Hence every detail of structure in every living creature (making some little allowance for the direct action of physical conditions) may be viewed, either as having been of special use to some ancestral form, or as being now of special use to the descendants of this form--either directly, or indirectly through the complex laws of growth. Natural selection cannot possibly produce any modification in any one species exclusively for the good of another species; though throughout nature one species incessantly takes advantage of, and profits by, the structure of another. But natural selection can and does often produce structures for the direct injury of other species, as we see in the fang of the adder, and in the ovipositor of the ichneumon, by which its eggs are {201} deposited in the living bodies of other insects. If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection. Although many statements may be found in works on natural history to this effect, I cannot find even one which seems to me of any weight. It is admitted that the rattlesnake has a poison-fang for its own defence and for the destruction of its prey; but some authors suppose that at the same time this snake is furnished with a rattle for its own injury, namely, to warn its prey to escape. I would almost as soon believe that the cat curls the end of its tail when preparing to spring, in order to warn the doomed mouse. But I have not space here to enter on this and other such cases. Natural selection will never produce in a being anything injurious to itself, for natural selection acts solely by and for the good of each. No organ will be formed, as Paley has remarked, for the purpose of causing pain or for doing an injury to its possessor. If a fair balance be struck between the good and evil caused by each part, each will be found on the whole advantageous. After the lapse of time, under changing conditions of life, if any part comes to be injurious, it will be modified; or if it be not so, the being will become extinct, as myriads have become extinct. Natural selection tends only to make each organic being as perfect as, or slightly more perfect than, the other inhabitants of the same country with which it has to struggle for existence. And we see that this is the degree of perfection attained under nature. The endemic productions of New Zealand, for instance, are perfect one compared with another; but they are now rapidly yielding before the advancing legions of plants {202} and animals introduced from Europe. Natural selection will not produce absolute perfection, nor do we always meet, as far as we can judge, with this high standard under nature. The correction for the aberration of light is said, on high authority, not to be perfect even in that most perfect organ, the eye. If our reason leads us to admire with enthusiasm a multitude of inimitable contrivances in nature, this same reason tells us, though we may easily err on both sides, that some other contrivances are less perfect. Can we consider the sting of the wasp or of the bee as perfect, which, when used against many attacking animals, cannot be withdrawn, owing to the backward serratures, and so inevitably causes the death of the insect by tearing out its viscera? If we look at the sting of the bee, as having originally existed in a remote progenitor as a boring and serrated instrument, like that in so many members of the same great order, and which has been modified but not perfected for its present purpose, with the poison originally adapted to cause galls subsequently intensified, we can perhaps understand how it is that the use of the sting should so often cause the insect's own death: for if on the whole the power of stinging be useful to the community, it will fulfil all the requirements of natural selection, though it may cause the death of some few members. If we admire the truly wonderful power of scent by which the males of many insects find their females, can we admire the production for this single purpose of thousands of drones, which are utterly useless to the community for any other end, and which are ultimately slaughtered by their industrious and sterile sisters? It may be difficult, but we ought to admire the savage instinctive hatred of the queen-bee, which urges her instantly to destroy the {203} young queens her daughters as soon as born, or to perish herself in the combat; for undoubtedly this is for the good of the community; and maternal love or maternal hatred, though the latter fortunately is most rare, is all the same to the inexorable principle of natural selection. If we admire the several ingenious contrivances, by which the flowers of the orchis and of many other plants are fertilised through insect agency, can we consider as equally perfect the elaboration by our fir-trees of dense clouds of pollen, in order that a few granules may be wafted by a chance breeze on to the ovules? _Summary of Chapter._--We have in this chapter discussed some of the difficulties and objections which may be urged against my theory. Many of them are very serious; but I think that in the discussion light has been thrown on several facts, which on the theory of independent acts of creation are utterly obscure. We have seen that species at any one period are not indefinitely variable, and are not linked together by a multitude of intermediate gradations, partly because the process of natural selection will always be very slow, and will act, at any one time, only on a very few forms; and partly because the very process of natural selection almost implies the continual supplanting and extinction of preceding and intermediate gradations. Closely allied species, now living on a continuous area, must often have been formed when the area was not continuous, and when the conditions of life did not insensibly graduate away from one part to another. When two varieties are formed in two districts of a continuous area, an intermediate variety will often be formed, fitted for an intermediate zone; but from reasons assigned, the intermediate variety will usually exist in lesser numbers than {204} the two forms which it connects; consequently the two latter, during the course of further modification, from existing in greater numbers, will have a great advantage over the less numerous intermediate variety, and will thus generally succeed in supplanting and exterminating it. We have seen in this chapter how cautious we should be in concluding that the most different habits of life could not graduate into each other; that a bat, for instance, could not have been formed by natural selection from an animal which at first could only glide through the air. We have seen that a species may under new conditions of life change its habits, or have diversified habits, with some habits very unlike those of its nearest congeners. Hence we can understand, bearing in mind that each organic being is trying to live wherever it can live, how it has arisen that there are upland geese with webbed feet, ground woodpeckers, diving thrushes, and petrels with the habits of auks. Although the belief that an organ so perfect as the eye could have been formed by natural selection, is more than enough to stagger any one; yet in the case of any organ, if we know of a long series of gradations in complexity, each good for its possessor, then, under changing conditions of life there is no logical impossibility in the acquirement of any conceivable degree of perfection through natural selection. In the cases in which we know of no intermediate or transitional states, we should be very cautious in concluding that none could have existed, for the homologies of many organs and their intermediate states show that wonderful metamorphoses in function are at least possible. For instance, a swim-bladder has apparently been converted into an air-breathing lung. The same organ having performed {205} simultaneously very different functions, and then having been specialised for one function; and two very distinct organs having performed at the same time the same function, the one having been perfected whilst aided by the other, must often have largely facilitated transitions. We are far too ignorant, in almost every case, to be enabled to assert that any part or organ is so unimportant for the welfare of a species, that modifications in its structure could not have been slowly accumulated by means of natural selection. But we may confidently believe that many modifications, wholly due to the laws of growth, and at first in no way advantageous to a species, have been subsequently taken advantage of by the still further modified descendants of this species. We may, also, believe that a part formerly of high importance has often been retained (as the tail of an aquatic animal by its terrestrial descendants), though it has become of such small importance that it could not, in its present state, have been acquired by natural selection,--a power which acts solely by the preservation of profitable variations in the struggle for life. Natural selection will produce nothing in one species for the exclusive good or injury of another; though it may well produce parts, organs, and excretions highly useful or even indispensable, or highly injurious to another species, but in all cases at the same time useful to the owner. Natural selection in each well-stocked country, must act chiefly through the competition of the inhabitants one with another, and consequently will produce perfection, or strength in the battle for life, only according to the standard of that country. Hence the inhabitants of one country, generally the smaller one, will often yield, as we see they do yield, to the inhabitants of another and generally larger country. For in {206} the larger country there will have existed more individuals, and more diversified forms, and the competition will have been severer, and thus the standard of perfection will have been rendered higher. Natural selection will not necessarily produce absolute perfection; nor, as far as we can judge by our limited faculties, can absolute perfection be everywhere found. On the theory of natural selection we can clearly understand the full meaning of that old canon in natural history, "Natura non facit saltum." This canon, if we look only to the present inhabitants of the world, is not strictly correct, but if we include all those of past times, it must by my theory be strictly true. It is generally acknowledged that all organic beings have been formed on two great laws--Unity of Type, and the Conditions of Existence. By unity of type is meant that fundamental agreement in structure, which we see in organic beings of the same class, and which is quite independent of their habits of life. On my theory, unity of type is explained by unity of descent. The expression of conditions of existence, so often insisted on by the illustrious Cuvier, is fully embraced by the principle of natural selection. For natural selection acts by either now adapting the varying parts of each being to its organic and inorganic conditions of life; or by having adapted them during long-past periods of time: the adaptations being aided in some cases by use and disuse, being slightly affected by the direct action of the external conditions of life, and being in all cases subjected to the several laws of growth. Hence, in fact, the law of the Conditions of Existence is the higher law; as it includes, through the inheritance of former adaptations, that of Unity of Type. * * * * * {207} CHAPTER VII. INSTINCT. Instincts comparable with habits, but different in their origin--Instincts graduated--Aphides and ants--Instincts variable--Domestic instincts, their origin--Natural instincts of the cuckoo, ostrich, and parasitic bees--Slave-making-ants--Hive-bee, its cell-making instinct--Difficulties on the theory of the Natural Selection of instincts--Neuter or sterile insects--Summary. The subject of instinct might have been worked into the previous chapters; but I have thought that it would be more convenient to treat the subject separately, especially as so wonderful an instinct as that of the hive-bee making its cells will probably have occurred to many readers, as a difficulty sufficient to overthrow my whole theory. I must premise, that I have nothing to do with the origin of the primary mental powers, any more than I have with that of life itself. We are concerned only with the diversities of instinct and of the other mental qualities of animals within the same class. I will not attempt any definition of instinct. It would be easy to show that several distinct mental actions are commonly embraced by this term; but every one understands what is meant, when it is said that instinct impels the cuckoo to migrate and to lay her eggs in other birds' nests. An action, which we ourselves should require experience to enable us to perform, when performed by an animal, more especially by a very young one, without any experience, and when performed by many individuals in the same way, without their knowing for what purpose it is performed, is usually said to be instinctive. {208} But I could show that none of these characters of instinct are universal. A little dose, as Pierre Huber expresses it, of judgment or reason, often comes into play, even in animals very low in the scale of nature. Frederick Cuvier and several of the older metaphysicians have compared instinct with habit. This comparison gives, I think, a remarkably accurate notion of the frame of mind under which an instinctive action is performed, but not of its origin. How unconsciously many habitual actions are performed, indeed not rarely in direct opposition to our conscious will! yet they may be modified by the will or reason. Habits easily become associated with other habits, and with certain periods of time and states of the body. When once acquired, they often remain constant throughout life. Several other points of resemblance between instincts and habits could be pointed out. As in repeating a well-known song, so in instincts, one action follows another by a sort of rhythm; if a person be interrupted in a song, or in repeating anything by rote, he is generally forced to go back to recover the habitual train of thought: so P. Huber found it was with a caterpillar, which makes a very complicated hammock; for if he took a caterpillar which had completed its hammock up to, say, the sixth stage of construction, and put it into a hammock completed up only to the third stage, the caterpillar simply re-performed the fourth, fifth, and sixth stages of construction. If, however, a caterpillar were taken out of a hammock made up, for instance, to the third stage, and were put into one finished up to the sixth stage, so that much of its work, was already done for it, far from feeling the benefit of this, it was much embarrassed, and, in order to complete its hammock, seemed forced to start from the third stage, where it had left off, and thus tried to complete the already finished work. {209} If we suppose any habitual action to become inherited--and I think it can be shown that this does sometimes happen--then the resemblance between what originally was a habit and an instinct becomes so close as not to be distinguished. If Mozart, instead of playing the pianoforte at three years old with wonderfully little practice, had played a tune with no practice at all, he might truly be said to have done so instinctively. But it would be the most serious error to suppose that the greater number of instincts have been acquired by habit in one generation, and then transmitted by inheritance to succeeding generations. It can be clearly shown that the most wonderful instincts with which we are acquainted, namely, those of the hive-bee and of many ants, could not possibly have been thus acquired. It will be universally admitted that instincts are as important as corporeal structure for the welfare of each species, under its present conditions of life. Under changed conditions of life, it is at least possible that slight modifications of instinct might be profitable to a species; and if it can be shown that instincts do vary ever so little, then I can see no difficulty in natural selection preserving and continually accumulating variations of instinct to any extent that may be profitable. It is thus, as I believe, that all the most complex and wonderful instincts have originated. As modifications of corporeal structure arise from, and are increased by, use or habit, and are diminished or lost by disuse, so I do not doubt it has been with instincts. But I believe that the effects of habit are of quite subordinate importance to the effects of the natural selection of what may be called accidental variations of instincts;--that is of variations produced by the same unknown causes which produce slight deviations of bodily structure. No complex instinct can possibly be produced through {210} natural selection, except by the slow and gradual accumulation of numerous, slight, yet profitable, variations. Hence, as in the case of corporeal structures, we ought to find in nature, not the actual transitional gradations by which each complex instinct has been acquired--for these could be found only in the lineal ancestors of each species--but we ought to find in the collateral lines of descent some evidence of such gradations; or we ought at least to be able to show that gradations of some kind are possible; and this we certainly can do. I have been surprised to find, making allowance for the instincts of animals having been but little observed except in Europe and North America, and for no instinct being known amongst extinct species, how very generally gradations, leading to the most complex instincts, can be discovered. Changes of instinct may sometimes be facilitated by the same species having different instincts at different periods of life, or at different seasons of the year, or when placed under different circumstances &c.; in which case either one or the other instinct might be preserved by natural selection. And such instances of diversity of instinct in the same species can be shown to occur in nature. Again as in the case of corporeal structure, and conformably with my theory, the instinct of each species is good for itself, but has never, as far as we can judge, been produced for the exclusive good of others. One of the strongest instances of an animal apparently performing an action for the sole good of another, with which I am acquainted, is that of aphides voluntarily yielding their sweet excretion to ants: that they do so voluntarily, the following facts show. I removed all the ants from a group of about a dozen aphides on a dock-plant, and prevented their attendance during several hours. After this interval, I felt sure that the aphides {211} would want to excrete. I watched them for some time through a lens, but not one excreted; I then tickled and stroked them with a hair in the same manner, as well as I could, as the ants do with their antennæ; but not one excreted. Afterwards I allowed an ant to visit them, and it immediately seemed, by its eager way of running about, to be well aware what a rich flock it had discovered; it then began to play with its antennæ on the abdomen first of one aphis and then of another; and each aphis, as soon as it felt the antennæ, immediately lifted up its abdomen and excreted a limpid drop of sweet juice, which was eagerly devoured by the ant. Even the quite young aphides behaved in this manner, showing that the action was instinctive, and not the result of experience. But as the excretion is extremely viscid, it is probably a convenience to the aphides to have it removed; and therefore probably the aphides do not instinctively excrete for the sole good of the ants. Although I do not believe that any animal in the world performs an action for the exclusive good of another of a distinct species, yet each species tries to take advantage of the instincts of others, as each takes advantage of the weaker bodily structure of others. So again, in some few cases, certain instincts cannot be considered as absolutely perfect; but as details on this and other such points are not indispensable, they may be here passed over. As some degree of variation in instincts under a state of nature, and the inheritance of such variations, are indispensable for the action of natural selection, as many instances as possible ought to be here given; but want of space prevents me. I can only assert, that instincts certainly do vary--for instance, the migratory instinct, both in extent and direction, and in its total loss. So it is with the nests of birds, which vary partly {212} in dependence on the situations chosen, and on the nature and temperature of the country inhabited, but often from causes wholly unknown to us: Audubon has given several remarkable cases of differences in the nests of the same species in the northern and southern United States. Fear of any particular enemy is certainly an instinctive quality, as may be seen in nestling birds, though it is strengthened by experience, and by the sight of fear of the same enemy in other animals. But fear of man is slowly acquired, as I have elsewhere shown, by various animals inhabiting desert islands; and we may see an instance of this, even in England, in the greater wildness of all our large birds than of our small birds; for the large birds have been most persecuted by man. We may safely attribute the greater wildness of our large birds to this cause; for in uninhabited islands large birds are not more fearful than small; and the magpie, so wary in England, is tame in Norway, as is the hooded crow in Egypt. That the general disposition of individuals of the same species, born in a state of nature, is extremely diversified, can be shown by a multitude of facts. Several cases also, could be given, of occasional and strange habits in certain species, which might, if advantageous to the species, give rise, through natural selection, to quite new instincts. But I am well aware that these general statements, without facts given in detail, can produce but a feeble effect on the reader's mind. I can only repeat my assurance, that I do not speak without good evidence. The possibility, or even probability, of inherited variations of instinct in a state of nature will be strengthened by briefly considering a few cases under domestication. We shall thus also be enabled to see the respective parts which habit and the selection of {213} so-called accidental variations have played in modifying the mental qualities of our domestic animals. A number of curious and authentic instances could be given of the inheritance of all shades of disposition and tastes, and likewise of the oddest tricks, associated with certain frames of mind or periods of time. But let us look to the familiar case of the several breeds of dogs: it cannot be doubted that young pointers (I have myself seen a striking instance) will sometimes point and even back other dogs the very first time that they are taken out; retrieving is certainly in some degree inherited by retrievers; and a tendency to run round, instead of at, a flock of sheep, by shepherd-dogs. I cannot see that these actions, performed without experience by the young, and in nearly the same manner by each individual, performed with eager delight by each breed, and without the end being known,--for the young pointer can no more know that he points to aid his master, than the white butterfly knows why she lays her eggs on the leaf of the cabbage,--I cannot see that these actions differ essentially from true instincts. If we were to see one kind of wolf, when young and without any training, as soon as it scented its prey, stand motionless like a statue, and then slowly crawl forward with a peculiar gait; and another kind of wolf rushing round, instead of at, a herd of deer, and driving them to a distant point, we should assuredly call these actions instinctive. Domestic instincts, as they may be called, are certainly far less fixed or invariable than natural instincts; but they have been acted on by far less rigorous selection, and have been transmitted for an incomparably shorter period, under less fixed conditions of life. How strongly these domestic instincts, habits, and dispositions are inherited, and how curiously they become mingled, is well shown when different breeds of dogs are {214} crossed. Thus it is known that a cross with a bull-dog has affected for many generations the courage and obstinacy of greyhounds; and a cross with a greyhound has given to a whole family of shepherd-dogs a tendency to hunt hares. These domestic instincts, when thus tested by crossing, resemble natural instincts, which in a like manner become curiously blended together, and for a long period exhibit traces of the instincts of either parent: for example, Le Roy describes a dog, whose great-grandfather was a wolf, and this dog showed a trace of its wild parentage only in one way, by not coming in a straight line to his master when called. Domestic instincts are sometimes spoken of as actions which have become inherited solely from long-continued and compulsory habit, but this, I think, is not true. No one would ever have thought of teaching, or probably could have taught, the tumbler-pigeon to tumble,--an action which, as I have witnessed, is performed by young birds, that have never seen a pigeon tumble. We may believe that some one pigeon showed a slight tendency to this strange habit, and that the long-continued selection of the best individuals in successive generations made tumblers what they now are; and near Glasgow there are house-tumblers, as I hear from Mr. Brent, which cannot fly eighteen inches high without going head over heels. It may be doubted whether any one would have thought of training a dog to point, had not some one dog naturally shown a tendency in this line; and this is known occasionally to happen, as I once saw in a pure terrier: the act of pointing is probably, as many have thought, only the exaggerated pause of an animal preparing to spring on its prey. When the first tendency to point was once displayed, methodical selection and the inherited effects of compulsory training in each successive generation would soon complete the {215} work; and unconscious selection is still at work, as each man tries to procure, without intending to improve the breed, dogs which will stand and hunt best. On the other hand, habit alone in some cases has sufficed; no animal is more difficult to tame than the young of the wild rabbit; scarcely any animal is tamer than the young of the tame rabbit; but I do not suppose that domestic rabbits have ever been selected for tameness; and I presume that we must attribute the whole of the inherited change from extreme wildness to extreme tameness, simply to habit and long-continued close confinement. Natural instincts are lost under domestication: a remarkable instance of this is seen in those breeds of fowls which very rarely or never become "broody," that is, never wish to sit on their eggs. Familiarity alone prevents our seeing how universally and largely the minds of our domestic animals have been modified by domestication. It is scarcely possible to doubt that the love of man has become instinctive in the dog. All wolves, foxes, jackals, and species of the cat genus, when kept tame, are most eager to attack poultry, sheep, and pigs; and this tendency has been found incurable in dogs which have been brought home as puppies from countries, such as Tierra del Fuego and Australia, where the savages do not keep these domestic animals. How rarely, on the other hand, do our civilised dogs, even when quite young, require to be taught not to attack poultry, sheep, and pigs! No doubt they occasionally do make an attack, and are then beaten; and if not cured, they are destroyed; so that habit, with some degree of selection, has probably concurred in civilising by inheritance our dogs. On the other hand, young chickens have lost, wholly by habit, that fear of the dog and cat which no doubt was originally instinctive in them, in the same way as it is so plainly instinctive in {216} young pheasants, though reared under a hen. It is not that chickens have lost all fear, but fear only of dogs and cats, for if the hen gives the danger-chuckle, they will run (more especially young turkeys) from under her, and conceal themselves in the surrounding grass or thickets; and this is evidently done for the instinctive purpose of allowing, as we see in wild ground-birds, their mother to fly away. But this instinct retained by our chickens has become useless under domestication, for the mother-hen has almost lost by disuse the power of flight. Hence, we may conclude, that domestic instincts have been acquired and natural instincts have been lost partly by habit, and partly by man selecting and accumulating during successive generations, peculiar mental habits and actions, which at first appeared from what we must in our ignorance call an accident. In some cases compulsory habit alone has sufficed to produce such inherited mental changes; in other cases compulsory habit has done nothing, and all has been the result of selection, pursued both methodically and unconsciously; but in most cases, probably, habit and selection have acted together. We shall, perhaps, best understand how instincts in a state of nature have become modified by selection, by considering a few cases. I will select only three, out of the several which I shall have to discuss in my future work,--namely, the instinct which leads the cuckoo to lay her eggs in other birds' nests; the slave-making instinct of certain ants; and the comb-making power of the hive-bee; these two latter instincts have generally, and most justly, been ranked by naturalists as the most wonderful of all known instincts. It is now commonly admitted that the more immediate and final cause of the cuckoo's instinct is, that {217} she lays her eggs, not daily, but at intervals of two or three days; so that, if she were to make her own nest and sit on her own eggs, those first laid would have to be left for some time unincubated, or there would be eggs and young birds of different ages in the same nest. If this were the case, the process of laying and hatching might be inconveniently long, more especially as she has to migrate at a very early period; and the first hatched young would probably have to be fed by the male alone. But the American cuckoo is in this predicament; for she makes her own nest and has eggs and young successively hatched, all at the same time. It has been asserted that the American cuckoo occasionally lays her eggs in other birds' nests; but I hear on the high authority of Dr. Brewer, that this is a mistake. Nevertheless, I could give several instances of various birds which have been known occasionally to lay their eggs in other birds' nests. Now let us suppose that the ancient progenitor of our European cuckoo had the habits of the American cuckoo; but that occasionally she laid an egg in another bird's nest. If the old bird profited by this occasional habit, or if the young were made more vigorous by advantage having been taken of the mistaken maternal instinct of another bird, than by their own mother's care, encumbered as she can hardly fail to be by having eggs and young of different ages at the same time; then the old birds or the fostered young would gain an advantage. And analogy would lead me to believe, that the young thus reared would be apt to follow by inheritance the occasional and aberrant habit of their mother, and in their turn would be apt to lay their eggs in other birds' nests, and thus be successful in rearing their young. By a continued process of this nature, I believe that the strange instinct of our cuckoo could be, and has been, {218} generated. I may add that, according to Dr. Gray and to some other observers, the European cuckoo has not utterly lost all maternal love and care for her own offspring. The occasional habit of birds laying their eggs in other birds' nests, either of the same or of a distinct species, is not very uncommon with the Gallinaceæ; and this perhaps explains the origin of a singular instinct in the allied group of ostriches. For several hen ostriches, at least in the case of the American species, unite and lay first a few eggs in one nest and then in another; and these are hatched by the males. This instinct may probably be accounted for by the fact of the hens laying a large number of eggs; but, as in the case of the cuckoo, at intervals of two or three days. This instinct, however, of the American ostrich has not as yet been perfected; for a surprising number of eggs lie strewed over the plains, so that in one day's hunting I picked up no less than twenty lost and wasted eggs. Many bees are parasitic, and always lay their eggs in the nests of bees of other kinds. This case is more remarkable than that of the cuckoo; for these bees have not only their instincts but their structure modified in accordance with their parasitic habits; for they do not possess the pollen-collecting apparatus which would be necessary if they had to store food for their own young. Some species, likewise, of Sphegidæ (wasp-like insects) are parasitic on other species; and M. Fabre has lately shown good reason for believing that although the Tachytes nigra generally makes its own burrow and stores it with paralysed prey for its own larvæ to feed on, yet that when this insect finds a burrow already made and stored by another sphex, it takes advantage of the prize, and becomes for the occasion parasitic. In this case, as with the supposed case of the cuckoo, I can {219} see no difficulty in natural selection making an occasional habit permanent, if of advantage to the species, and if the insect whose nest and stored food are thus feloniously appropriated, be not thus exterminated. _Slave-making instinct._--This remarkable instinct was first discovered in the Formica (Polyerges) rufescens by Pierre Huber, a better observer even than his celebrated father. This ant is absolutely dependent on its slaves; without their aid, the species would certainly become extinct in a single year. The males and fertile females do no work. The workers or sterile females, though most energetic and courageous in capturing slaves, do no other work. They are incapable of making their own nests, or of feeding their own larvæ. When the old nest is found inconvenient, and they have to migrate, it is the slaves which determine the migration, and actually carry their masters in their jaws. So utterly helpless are the masters, that when Huber shut up thirty of them without a slave, but with plenty of the food which they like best, and with their larvae and pupæ to stimulate them to work, they did nothing; they could not even feed themselves, and many perished of hunger. Huber then introduced a single slave (F. fusca), and she instantly set to work, fed and saved the survivors; made some cells and tended the larvæ, and put all to rights. What can be more extraordinary than these well-ascertained facts? If we had not known of any other slave-making ant, it would have been hopeless to have speculated how so wonderful an instinct could have been perfected. Another species, Formica sanguinea, was likewise first discovered by P. Huber to be a slave-making ant. This species is found in the southern parts of England, and its habits have been attended to by Mr. F. Smith, of {220} the British Museum, to whom I am much indebted for information on this and other subjects. Although fully trusting to the statements of Huber and Mr. Smith, I tried to approach the subject in a sceptical frame of mind, as any one may well be excused for doubting the truth of so extraordinary and odious an instinct as that of making slaves. Hence I will give the observations which I have myself made, in some little detail. I opened fourteen nests of F. sanguinea, and found a few slaves in all. Males and fertile females of the slave-species (F. fusca) are found only in their own proper communities, and have never been observed in the nests of F. sanguinea. The slaves are black and not above half the size of their red masters, so that the contrast in their appearance is very great. When the nest is slightly disturbed, the slaves occasionally come out, and like their masters are much agitated and defend the nest: when the nest is much disturbed and the larvæ and pupæ are exposed, the slaves work energetically with their masters in carrying them away to a place of safety. Hence, it is clear, that the slaves feel quite at home. During the months of June and July, on three successive years, I have watched for many hours several nests in Surrey and Sussex, and never saw a slave either leave or enter a nest. As, during these months, the slaves are very few in number, I thought that they might behave differently when more numerous; but Mr. Smith informs me that he has watched the nests at various hours during May, June and August, both in Surrey and Hampshire, and has never seen the slaves, through present in large numbers in August, either leave or enter the nest. Hence he considers them as strictly household slaves. The masters, on the other hand, may be constantly seen bringing in materials for the nest, and food of all kinds. During the present year, however, in the month {221} of July, I came across a community with an unusually large stock of slaves, and I observed a few slaves mingled with their masters leaving the nest, and marching along the same road to a tall Scotch-fir-tree, twenty-five yards distant, which they ascended together, probably in search of aphides or cocci. According to Huber, who had ample opportunities for observation, in Switzerland the slaves habitually work with their masters in making the nest, and they alone open and close the doors in the morning and evening; and, as Huber expressly states, their principal office is to search for aphides. This difference in the usual habits of the masters and slaves in the two countries, probably depends merely on the slaves being captured in greater numbers in Switzerland than in England. One day I fortunately witnessed a migration of F. sanguinea from one nest to another, and it was a most interesting spectacle to behold the masters carefully carrying (instead of being carried by, as in the case of F. rufescens) their slaves in their jaws. Another day my attention was struck by about a score of the slave-makers haunting the same spot, and evidently not in search of food; they approached and were vigorously repulsed by an independent community of the slave-species (F. fusca); sometimes as many as three of these ants clinging to the legs of the slave-making F. sanguinea. The latter ruthlessly killed their small opponents, and carried their dead bodies as food to their nest, twenty-nine yards distant; but they were prevented from getting any pupæ to rear as slaves. I then dug up a small parcel of the pupæ of F. fusca from another nest, and put them down on a bare spot near the place of combat; they were eagerly seized, and carried off by the tyrants, who perhaps fancied that, after all, they had been victorious in their late combat. {222} At the same time I laid on the same place a small parcel of the pupæ of another species, F. flava, with a few of these little yellow ants still clinging to the fragments of the nest. This species is sometimes, though rarely, made into slaves, as has been described by Mr. Smith. Although so small a species, it is very courageous, and I have seen it ferociously attack other ants. In one instance I found to my surprise an independent community of F. flava under a stone beneath a nest of the slave-making F. sanguinea; and when I had accidentally disturbed both nests, the little ants attacked their big neighbours with surprising courage. Now I was curious to ascertain whether F. sanguinea could distinguish the pupæ of F. fusca, which they habitually make into slaves, from those of the little and furious F. flava, which they rarely capture, and it was evident that they did at once distinguish them: for we have seen that they eagerly and instantly seized the pupæ of F. fusca, whereas they were much terrified when they came across the pupæ, or even the earth from the nest of F. flava, and quickly ran away; but in about a quarter of an hour, shortly after all the little yellow ants had crawled away, they took heart and carried off the pupæ. One evening I visited another community of F. sanguinea, and found a number of these ants returning home and entering their nests, carrying the dead bodies of F. fusca (showing that it was not a migration) and numerous pupæ. I traced a long file of ants burthened with booty, for about forty yards, to a very thick clump of heath, whence I saw the last individual of F. sanguinea emerge, carrying a pupa; but I was not able to find the desolated nest in the thick heath. The nest, however, must have been close at hand, for two or three individuals of F. fusca were rushing about in the greatest {223} agitation, and one was perched motionless with its own pupa in its mouth on the top of a spray of heath, an image of despair, over its ravaged home. Such are the facts, though they did not need confirmation by me, in regard to the wonderful instinct of making slaves. Let it be observed what a contrast the instinctive habits of F. sanguinea present with those of the continental F. rufescens. The latter does not build its own nest, does not determine its own migrations, does not collect food for itself or its young, and cannot even feed itself: it is absolutely dependent on its numerous slaves. Formica sanguinea, on the other hand, possesses much fewer slaves, and in the early part of the summer extremely few: the masters determine when and where a new nest shall be formed, and when they migrate, the masters carry the slaves. Both in Switzerland and England the slaves seem to have the exclusive care of the larvæ, and the masters alone go on slave-making expeditions. In Switzerland the slaves and masters work together, making and bringing materials for the nest: both, but chiefly the slaves, tend, and milk as it may be called, their aphides; and thus both collect food for the community. In England the masters alone usually leave the nest to collect building materials and food for themselves, their slaves and larvæ. So that the masters in this country receive much less service from their slaves than they do in Switzerland. By what steps the instinct of F. sanguinea originated I will not pretend to conjecture. But as ants, which are not slave-makers, will, as I have seen, carry off pupæ of other species, if scattered near their nests, it is possible that such pupæ originally stored as food might become developed; and the foreign ants thus unintentionally reared would then follow their proper instincts, and do {224} what work they could. If their presence proved useful to the species which had seized them--if it were more advantageous to this species to capture workers than to procreate them--the habit of collecting pupae originally for food might by natural selection be strengthened and rendered permanent for the very different purpose of raising slaves. When the instinct was once acquired, if carried out to a much less extent even than in our British F. sanguinea, which, as we have seen, is less aided by its slaves than the same species in Switzerland, I can see no difficulty in natural selection increasing and modifying the instinct--always supposing each modification to be of use to the species--until an ant was formed as abjectly dependent on its slaves as is the Formica rufescens. _Cell-making instinct of the Hive-Bee._--I will not here enter on minute details on this subject, but will merely give an outline of the conclusions at which I have arrived. He must be a dull man who can examine the exquisite structure of a comb, so beautifully adapted to its end, without enthusiastic admiration. We hear from mathematicians that bees have practically solved a recondite problem, and have made their cells of the proper shape to hold the greatest possible amount of honey, with the least possible consumption of precious wax in their construction. It has been remarked that a skilful workman, with fitting tools and measures, would find it very difficult to make cells of wax of the true form, though this is perfectly effected by a crowd of bees working in a dark hive. Grant whatever instincts you please, and it seems at first quite inconceivable how they can make all the necessary angles and planes, or even perceive when they are correctly made. But the difficulty is not {225} nearly so great as it at first appears: all this beautiful work can be shown, I think, to follow from a few very simple instincts. I was led to investigate this subject by Mr. Waterhouse, who has shown that the form of the cell stands in close relation to the presence of adjoining cells; and the following view may, perhaps, be considered only as a modification of his theory. Let us look to the great principle of gradation, and see whether Nature does not reveal to us her method of work. At one end of a short series we have humble-bees, which use their old cocoons to hold honey, sometimes adding to them short tubes of wax, and likewise making separate and very irregular rounded cells of wax. At the other end of the series we have the cells of the hive-bee, placed in a double layer: each cell, as is well known, is an hexagonal prism, with the basal edges of its six sides bevelled so as to fit on to a pyramid, formed of three rhombs. These rhombs have certain angles, and the three which form the pyramidal base of a single cell on one side of the comb, enter into the composition of the bases of three adjoining cells on the opposite side. In the series between the extreme perfection of the cells of the hive-bee and the simplicity of those of the humble-bee, we have the cells of the Mexican Melipona domestica, carefully described and figured by Pierre Huber. The Melipona itself is intermediate in structure between the hive and humble bee, but more nearly related to the latter: it forms a nearly regular waxen comb of cylindrical cells, in which the young are hatched, and, in addition, some large cells of wax for holding honey. These latter cells are nearly spherical and of nearly equal sizes, and are aggregated into an irregular mass. But the important point to notice, is that these cells are always made at that degree of nearness to each other, that they would have {226} intersected or broken into each other, if the spheres had been completed; but this is never permitted, the bees building perfectly flat walls of wax between the spheres which thus tend to intersect. Hence each cell consists of an outer spherical portion and of two, three, or more perfectly flat surfaces, according as the cell adjoins two, three, or more other cells. When one cell comes into contact with three other cells, which, from the spheres being nearly of the same size, is very frequently and necessarily the case, the three flat surfaces are united into a pyramid; and this pyramid, as Huber has remarked, is manifestly a gross imitation of the three-sided pyramidal bases of the cell of the hive-bee. As in the cells of the hive-bee, so here, the three plane surfaces in any one cell necessarily enter into the construction of three adjoining cells. It is obvious that the Melipona saves wax by this manner of building; for the flat walls between the adjoining cells are not double, but are of the same thickness as the outer spherical portions, and yet each flat portion forms a part of two cells. Reflecting on this case, it occurred to me that if the Melipona had made its spheres at some given distance from each other, and had made them of equal sizes and had arranged them symmetrically in a double layer, the resulting structure would probably have been as perfect as the comb of the hive-bee. Accordingly I wrote to Professor Miller, of Cambridge, and this geometer has kindly read over the following statement, drawn up from his information, and tells me that it is strictly correct:-- If a number of equal spheres be described with their centres placed in two parallel layers; with the centre of each sphere at the distance of radius × [root]2, or radius × 1.41421 (or at some lesser distance), from the centres of the six surrounding spheres in the same {227} layer; and at the same distance from the centres of the adjoining spheres in the other and parallel layer; then, if planes of intersection between the several spheres in both layers be formed, there will result a double layer of hexagonal prisms united together by pyramidal bases formed of three rhombs; and the rhombs and the sides of the hexagonal prisms will have every angle identically the same with the best measurements which have been made of the cells of the hive-bee. Hence we may safely conclude that if we could slightly modify the instincts already possessed by the Melipona, and in themselves not very wonderful, this bee would make a structure as wonderfully perfect as that of the hive-bee. We must suppose the Melipona to make her cells truly spherical, and of equal sizes; and this would not be very surprising, seeing that she already does so to a certain extent, and seeing what perfectly cylindrical burrows in wood many insects can make, apparently by turning round on a fixed point. We must suppose the Melipona to arrange her cells in level layers, as she already does her cylindrical cells; and we must further suppose, and this is the greatest difficulty, that she can somehow judge accurately at what distance to stand from her fellow-labourers when several are making their spheres; but she is already so far enabled to judge of distance, that she always describes her spheres so as to intersect largely; and then she unites the points of intersection by perfectly flat surfaces. We have further to suppose, but this is no difficulty, that after hexagonal prisms have been formed by the intersection of adjoining spheres in the same layer, she can prolong the hexagon to any length requisite to hold the stock of honey; in the same way as the rude humble-bee adds cylinders of wax to the circular mouths of her old cocoons. By such {228} modifications of instincts in themselves not very wonderful,--hardly more wonderful than those which guide a bird to make its nest,--I believe that the hive-bee has acquired, through natural selection, her inimitable architectural powers. But this theory can be tested by experiment. Following the example of Mr. Tegetmeier, I separated two combs, and put between them a long, thick, square strip of wax: the bees instantly began to excavate minute circular pits in it; and as they deepened these little pits, they made them wider and wider until they were converted into shallow basins, appearing to the eye perfectly true or parts of a sphere, and of about the diameter of a cell. It was most interesting to me to observe that wherever several bees had begun to excavate these basins near together, they had begun their work at such a distance from each other, that by the time the basins had acquired the above stated width (_i.e._ about the width of an ordinary cell), and were in depth about one sixth of the diameter of the sphere of which they formed a part, the rims of the basins intersected or broke into each other. As soon as this occurred, the bees ceased to excavate, and began to build up flat walls of wax on the lines of intersection between the basins, so that each hexagonal prism was built upon the scalloped edge of a smooth basin, instead of on the straight edges of a three-sided pyramid as in the case of ordinary cells. I then put into the hive, instead of a thick, square piece of wax, a thin and narrow, knife-edged ridge, coloured with vermilion. The bees instantly began on both sides to excavate little basins near to each other, in the same way as before; but the ridge of wax was so thin, that the bottoms of the basins, if they had been excavated to the same depth as in the former {229} experiment, would have broken into each other from the opposite sides. The bees, however, did not suffer this to happen, and they stopped their excavations in due time; so that the basins, as soon as they had been a little deepened, came to have flat bottoms; and these flat bottoms, formed by thin little plates of the vermilion wax having been left ungnawed, were situated, as far as the eye could judge, exactly along the planes of imaginary intersection between the basins on the opposite sides of the ridge of wax. In parts, only little bits, in other parts, large portions of a rhombic plate had been left between the opposed basins, but the work, from the unnatural state of things, had not been neatly performed. The bees must have worked at very nearly the same rate on the opposite sides of the ridge of vermilion wax, as they circularly gnawed away and deepened the basins on both sides, in order to have succeeded in thus leaving flat plates between the basins, by stopping work along the intermediate planes or planes of intersection. Considering how flexible thin wax is, I do not see that there is any difficulty in the bees, whilst at work on the two sides of a strip of wax, perceiving when they have gnawed the wax away to the proper thinness, and then stopping their work. In ordinary combs it has appeared to me that the bees do not always succeed in working at exactly the same rate from the opposite sides; for I have noticed half-completed rhombs at the base of a just-commenced cell, which were slightly concave on one side, where I suppose that the bees had excavated too quickly, and convex on the opposed side, where the bees had worked less quickly. In one well-marked instance, I put the comb back into the hive, and allowed the bees to go on working for a short time, and again examined the cell, and I found that the rhombic {230} plate had been completed, and had become _perfectly flat_: it was absolutely impossible, from the extreme thinness of the little rhombic plate, that they could have effected this by gnawing away the convex side; and I suspect that the bees in such cases stand in the opposed cells and push and bend the ductile and warm wax (which as I have tried is easily done) into its proper intermediate plane, and thus flatten it. From the experiment of the ridge of vermilion wax, we can clearly see that if the bees were to build for themselves a thin wall of wax, they could make their cells of the proper shape, by standing at the proper distance from each other, by excavating at the same rate, and by endeavouring to make equal spherical hollows, but never allowing the spheres to break into each other. Now bees, as may be clearly seen by examining the edge of a growing comb, do make a rough, circumferential wall or rim all round the comb; and they gnaw into this from the opposite sides, always working circularly as they deepen each cell. They do not make the whole three-sided pyramidal base of any one cell at the same time, but only the one rhombic plate which stands on the extreme growing margin, or the two plates, as the case may be; and they never complete the upper edges of the rhombic plates, until the hexagonal walls are commenced. Some of these statements differ from those made by the justly celebrated elder Huber, but I am convinced of their accuracy; and if I had space, I could show that they are conformable with my theory. Huber's statement that the very first cell is excavated out of a little parallel-sided wall of wax, is not, as far as I have seen, strictly correct; the first commencement having always been a little hood of wax; but I will not here enter on these details. We see how important {231} a part excavation plays in the construction of the cells; but it would be a great error to suppose that the bees cannot build up a rough wall of wax in the proper position--that is, along the plane of intersection between two adjoining spheres. I have several specimens showing clearly that they can do this. Even in the rude circumferential rim or wall of wax round a growing comb, flexures may sometimes be observed, corresponding in position to the planes of the rhombic basal plates of future cells. But the rough wall of wax has in every case to be finished off, by being largely gnawed away on both sides. The manner in which the bees build is curious; they always make the first rough wall from ten to twenty times thicker than the excessively thin finished wall of the cell, which will ultimately be left. We shall understand how they work, by supposing masons first to pile up a broad ridge of cement, and then to begin cutting it away equally on both sides near the ground, till a smooth, very thin wall is left in the middle; the masons always piling up the cut-away cement, and adding fresh cement, on the summit of the ridge. We shall thus have a thin wall steadily growing upward; but always crowned by a gigantic coping. From all the cells, both those just commenced and those completed, being thus crowned by a strong coping of wax, the bees can cluster and crawl over the comb without injuring the delicate hexagonal walls, which are only about one four-hundredth of an inch in thickness; the plates of the pyramidal basis being about twice as thick. By this singular manner of building, strength is continually given to the comb, with the utmost ultimate economy of wax. It seems at first to add to the difficulty of understanding how the cells are made, that a multitude of bees all work together; one bee after working a short time at one cell going to another, so that, as Huber has stated, {232} a score of individuals work even at the commencement of the first cell. I was able practically to show this fact, by covering the edges of the hexagonal walls of a single cell, or the extreme margin of the circumferential rim of a growing comb, with an extremely thin layer of melted vermilion wax; and I invariably found that the colour was most delicately diffused by the bees--as delicately as a painter could have done with his brush--by atoms of the coloured wax having been taken from the spot on which it had been placed, and worked into the growing edges of the cells all round. The work of construction seems to be a sort of balance struck between many bees, all instinctively standing at the same relative distance from each other, all trying to sweep equal spheres, and then building up, or leaving ungnawed, the planes of intersection between these spheres. It was really curious to note in cases of difficulty, as when two pieces of comb met at an angle, how often the bees would pull down and rebuild in different ways the same cell, sometimes recurring to a shape which they had at first rejected. When bees have a place on which they can stand in their proper positions for working,--for instance, on a slip of wood, placed directly under the middle of a comb growing downwards so that the comb has to be built over one face of the slip--in this case the bees can lay the foundations of one wall of a new hexagon, in its strictly proper place, projecting beyond the other completed cells. It suffices that the bees should be enabled to stand at their proper relative distances from each other and from the walls of the last completed cells, and then, by striking imaginary spheres, they can build up a wall intermediate between two adjoining spheres; but, as far as I have seen, they never gnaw away and finish off the angles of a cell till a large part both of that cell and of {233} the adjoining cells has been built. This capacity in bees of laying down under certain circumstances a rough wall in its proper place between two just-commenced cells, is important, as it bears on a fact, which seems at first quite subversive of the foregoing theory; namely, that the cells on the extreme margin of wasp-combs are sometimes strictly hexagonal; but I have not space here to enter on this subject. Nor does there seem to me any great difficulty in a single insect (as in the case of a queen-wasp) making hexagonal cells, if she work alternately on the inside and outside of two or three cells commenced at the same time, always standing at the proper relative distance from the parts of the cells just begun, sweeping spheres or cylinders, and building up intermediate planes. It is even conceivable that an insect might, by fixing on a point at which to commence a cell, and then moving outside, first to one point, and then to five other points, at the proper relative distances from the central point and from each other, strike the planes of intersection, and so make an isolated hexagon: but I am not aware that any such case has been observed; nor would any good be derived from a single hexagon being built, as in its construction more materials would be required than for a cylinder. As natural selection acts only by the accumulation of slight modifications of structure or instinct, each profitable to the individual under its conditions of life, it may reasonably be asked, how a long and graduated succession of modified architectural instincts, all tending towards the present perfect plan of construction, could have profited the progenitors of the hive-bee? I think the answer is not difficult: it is known that bees are often hard pressed to get sufficient nectar; and I am informed by Mr. Tegetmeier that it has been experimentally found that no less than from twelve to fifteen pounds of dry sugar {234} are consumed by a hive of bees for the secretion of each pound of wax; to that a prodigious quantity of fluid nectar must be collected and consumed by the bees in a hive for the secretion of the wax necessary for the construction of their combs. Moreover, many bees have to remain idle for many days during the process of secretion. A large store of honey is indispensable to support a large stock of bees during the winter; and the security of the hive is known mainly to depend on a large number of bees being supported. Hence the saving of wax by largely saving honey must be a most important element of success in any family of bees. Of course the success of any species of bee may be dependent on the number of its parasites or other enemies, or on quite distinct causes, and so be altogether independent of the quantity of honey which the bees could collect. But let us suppose that this latter circumstance determined, as it probably often does determine, the numbers of a humble-bee which could exist in a country; and let us further suppose that the community lived throughout the winter, and consequently required a store of honey: there can in this case be no doubt that it would be an advantage to our humble-bee, if a slight modification of her instinct led her to make her waxen cells near together, so as to intersect a little; for a wall in common even to two adjoining cells, would save some little wax. Hence it would continually be more and more advantageous to our humble-bee, if she were to make her cells more and more regular, nearer together, and aggregated into a mass, like the cells of the Melipona; for in this case a large part of the bounding surface of each cell would serve to bound other cells, and much wax would be saved. Again, from the same cause, it would be advantageous to the Melipona, if she were to make her cells closer together, and more regular in every way {235} than at present; for then, as we have seen, the spherical surfaces would wholly disappear, and would all be replaced by plane surfaces; and the Melipona would make a comb as perfect as that of the hive-bee. Beyond this stage of perfection in architecture, natural selection could not lead; for the comb of the hive-bee, as far as we can see, is absolutely perfect in economising wax. Thus, as I believe, the most wonderful of all known instincts, that of the hive-bee, can be explained by natural selection having taken advantage of numerous, successive, slight modifications of simpler instincts; natural selection having by slow degrees, more and more perfectly, led the bees to sweep equal spheres at a given distance from each other in a double layer, and to build up and excavate the wax along the planes of intersection. The bees, of course, no more knowing that they swept their spheres at one particular distance from each other, than they know what are the several angles of the hexagonal prisms and of the basal rhombic plates. The motive power of the process of natural selection having been economy of wax; that individual swarm which wasted least honey in the secretion of wax, having succeeded best, and having transmitted by inheritance its newly acquired economical instinct to new swarms, which in their turn will have had the best chance of succeeding in the struggle for existence. No doubt many instincts of very difficult explanation could be opposed to the theory of natural selection,--cases, in which we cannot see how an instinct could possibly have originated; cases, in which no intermediate gradations are known to exist; cases of instinct of apparently such trifling importance, that they could {236} hardly have been acted on by natural selection; cases of instincts almost identically the same in animals so remote in the scale of nature, that we cannot account for their similarity by inheritance from a common parent, and must therefore believe that they have been acquired by independent acts of natural selection. I will not here enter on these several cases, but will confine myself to one special difficulty, which at first appeared to me insuperable, and actually fatal to my whole theory. I allude to the neuters or sterile females in insect-communities: for these neuters often differ widely in instinct and in structure from both the males and fertile females, and yet, from being sterile, they cannot propagate their kind. The subject well deserves to be discussed at great length, but I will here take only a single case, that of working or sterile ants. How the workers have been rendered sterile is a difficulty; but not much greater than that of any other striking modification of structure; for it can be shown that some insects and other articulate animals in a state of nature occasionally become sterile; and if such insects had been social, and it had been profitable to the community that a number should have been annually born capable of work, but incapable of procreation, I can see no very great difficulty in this being effected by natural selection. But I must pass over this preliminary difficulty. The great difficulty lies in the working ants differing widely from both the males and the fertile females in structure, as in the shape of the thorax and in being destitute of wings and sometimes of eyes, and in instinct. As far as instinct alone is concerned, the prodigious difference in this respect between the workers and the perfect females, would have been far better exemplified by the hive-bee. If a working ant or other neuter insect had been an animal {237} in the ordinary state, I should have unhesitatingly assumed that all its characters had been slowly acquired through natural selection; namely, by an individual having been born with some slight profitable modification of structure, this being inherited by its offspring, which again varied and were again selected, and so onwards. But with the working ant we have an insect differing greatly from its parents, yet absolutely sterile; so that it could never have transmitted successively acquired modifications of structure or instinct to its progeny. It may well be asked how is it possible to reconcile this case with the theory of natural selection? First, let it be remembered that we have innumerable instances, both in our domestic productions and in those in a state of nature, of all sorts of differences of structure which have become correlated to certain ages, and to either sex. We have differences correlated not only to one sex, but to that short period alone when the reproductive system is active, as in the nuptial plumage of many birds, and in the hooked jaws of the male salmon. We have even slight differences in the horns of different breeds of cattle in relation to an artificially imperfect state of the male sex; for oxen of certain breeds have longer horns than in other breeds, in comparison with the horns of the bulls or cows of these same breeds. Hence I can see no real difficulty in any character having become correlated with the sterile condition of certain members of insect-communities: the difficulty lies in understanding how such correlated modifications of structure could have been slowly accumulated by natural selection. This difficulty, though appearing insuperable, is lessened, or, as I believe, disappears, when it is remembered that selection may be applied to the family, as well as to the individual, and may thus gain the {238} desired end. Thus, a well-flavoured vegetable is cooked, and the individual is destroyed; but the horticulturist sows seeds of the same stock, and confidently expects to get nearly the same variety: breeders of cattle wish the flesh and fat to be well marbled together; the animal has been slaughtered, but the breeder goes with confidence to the same family. I have such faith in the powers of selection, that I do not doubt that a breed of cattle, always yielding oxen with extraordinarily long horns, could be slowly formed by carefully watching which individual bulls and cows, when matched, produced oxen with the longest horns; and yet no one ox could ever have propagated its kind. Thus I believe it has been with social insects: a slight modification of structure, or instinct, correlated with the sterile condition of certain members of the community, has been advantageous to the community: consequently the fertile males and females of the same community flourished, and transmitted to their fertile offspring a tendency to produce sterile members having the same modification. And I believe that this process has been repeated, until that prodigious amount of difference between the fertile and sterile females of the same species has been produced, which we see in many social insects. But we have not as yet touched on the climax of the difficulty; namely, the fact that the neuters of several ants differ, not only from the fertile females and males, but from each other, sometimes to an almost incredible degree, and are thus divided into two or even three castes. The castes, moreover, do not generally graduate into each other, but are perfectly well defined; being as distinct from each other, as are any two species of the same genus, or rather as any two genera of the same family. Thus in Eciton, there are working and soldier neuters, with jaws and instincts extraordinarily {239} different: in Cryptocerus, the workers of one caste alone carry a wonderful sort of shield on their heads, the use of which is quite unknown: in the Mexican Myrmecocystus, the workers of one caste never leave the nest; they are fed by the workers of another caste, and they have an enormously developed abdomen which secretes a sort of honey, supplying the place of that excreted by the aphides, or the domestic cattle as they may be called, which our European ants guard or imprison. It will indeed be thought that I have an overweening confidence in the principle of natural selection, when I do not admit that such wonderful and well-established facts at once annihilate my theory. In the simpler case of neuter insects all of one caste or of the same kind, which have been rendered by natural selection, as I believe to be quite possible, different from the fertile males and females,--in this case, we may safely conclude from the analogy of ordinary variations, that each successive, slight, profitable modification did not probably at first appear in all the individual neuters in the same nest, but in a few alone; and that by the long-continued selection of the fertile parents which produced most neuters with the profitable modification, all the neuters ultimately came to have the desired character. On this view we ought occasionally to find neuter-insects of the same species, in the same nest, presenting gradations of structure; and this we do find, even often, considering how few neuter-insects out of Europe have been carefully examined. Mr. F. Smith has shown how surprisingly the neuters of several British ants differ from each other in size and sometimes in colour; and that the extreme forms can sometimes be perfectly linked together by individuals taken out of the same nest: I have myself compared perfect gradations of this kind. It often happens that the larger or the smaller sized workers {240} are the most numerous; or that both large and small are numerous, with those of an intermediate size scanty in numbers. Formica flava has larger and smaller workers, with some of intermediate size; and, in this species, as Mr. F. Smith has observed, the larger workers have simple eyes (ocelli), which though small can be plainly distinguished, whereas the smaller workers have their ocelli rudimentary. Having carefully dissected several specimens of these workers, I can affirm that the eyes are far more rudimentary in the smaller workers than can be accounted for merely by their proportionally lesser size; and I fully believe, though I dare not assert so positively, that the workers of intermediate size have their ocelli in an exactly intermediate condition. So that we here have two bodies of sterile workers in the same nest, differing not only in size, but in their organs of vision, yet connected by some few members in an intermediate condition. I may digress by adding, that if the smaller workers had been the most useful to the community, and those males and females had been continually selected, which produced more and more of the smaller workers, until all the workers had come to be in this condition; we should then have had a species of ant with neuters very nearly in the same condition with those of Myrmica. For the workers of Myrmica have not even rudiments of ocelli, though the male and female ants of this genus have well-developed ocelli. I may give one other case: so confidently did I expect to find gradations in important points of structure between the different castes of neuters in the same species, that I gladly availed myself of Mr. F. Smith's offer of numerous specimens from the same nest of the driver ant (Anomma) of West Africa. The reader will perhaps best appreciate the amount of difference in these {241} workers, by my giving not the actual measurements, but a strictly accurate illustration: the difference was the same as if we were to see a set of workmen building a house of whom many were five feet four inches high, and many sixteen feet high; but we must suppose that the larger workmen had heads four instead of three times as big as those of the smaller men, and jaws nearly five times as big. The jaws, moreover, of the working ants of the several sizes differed wonderfully in shape, and in the form and number of the teeth. But the important fact for us is, that though the workers can be grouped into castes of different sizes, yet they graduate insensibly into each other, as does the widely-different structure of their jaws. I speak confidently on this latter point, as Mr. Lubbock made drawings for me with the camera lucida of the jaws which I had dissected from the workers of the several sizes. With these facts before me, I believe that natural selection, by acting on the fertile parents, could form a species which should regularly produce neuters, either all of large size with one form of jaw, or all of small size with jaws having a widely different structure; or lastly, and this is our climax of difficulty, one set of workers of one size and structure, and simultaneously another set of workers of a different size and structure;--a graduated series having been first formed, as in the case of the driver ant, and then the extreme forms, from being the most useful to the community, having been produced in greater and greater numbers through the natural selection of the parents which generated them; until none with an intermediate structure were produced. Thus, as I believe, the wonderful fact of two distinctly defined castes of sterile workers existing in the same nest, both widely different from each other and from {242} their parents, has originated. We can see how useful their production may have been to a social community of insects, on the same principle that the division of labour is useful to civilised man. As ants work by inherited instincts and by inherited organs or tools, and not by acquired knowledge and manufactured instruments, a perfect division of labour could be effected with them only by the workers being sterile; for had they been fertile, they would have intercrossed, and their instincts and structure would have become blended. And nature has, as I believe, effected this admirable division of labour in the communities of ants, by the means of natural selection. But I am bound to confess, that, with all my faith in this principle, I should never have anticipated that natural selection could have been efficient in so high a degree, had not the case of these neuter insects convinced me of the fact. I have, therefore, discussed this case, at some little but wholly insufficient length, in order to show the power of natural selection, and likewise because this is by far the most serious special difficulty, which my theory has encountered. The case, also, is very interesting, as it proves that with animals, as with plants, any amount of modification in structure can be effected by the accumulation of numerous, slight, and as we must call them accidental, variations, which are in any manner profitable, without exercise or habit having come into play. For no amount of exercise, or habit, or volition, in the utterly sterile members of a community could possibly affect the structure or instincts of the fertile members, which alone leave descendants. I am surprised that no one has advanced this demonstrative case of neuter insects, against the well-known doctrine of Lamarck. _Summary._--I have endeavoured briefly in this chapter {243} to show that the mental qualities of our domestic animals vary, and that the variations are inherited. Still more briefly I have attempted to show that instincts vary slightly in a state of nature. No one will dispute that instincts are of the highest importance to each animal. Therefore I can see no difficulty, under changing conditions of life, in natural selection accumulating slight modifications of instinct to any extent, in any useful direction. In some cases habit or use and disuse have probably come into play. I do not pretend that the facts given in this chapter strengthen in any great degree my theory; but none of the cases of difficulty, to the best of my judgment, annihilate it. On the other hand, the fact that instincts are not always absolutely perfect and are liable to mistakes;--that no instinct has been produced for the exclusive good of other animals, but that each animal takes advantage of the instincts of others;--that the canon in natural history, of "Natura non facit saltum," is applicable to instincts as well as to corporeal structure, and is plainly explicable on the foregoing views, but is otherwise inexplicable,--all tend to corroborate the theory of natural selection. This theory is, also, strengthened by some few other facts in regard to instincts; as by that common case of closely allied, but certainly distinct, species, when inhabiting distant parts of the world and living under considerably different conditions of life, yet often retaining nearly the same instincts. For instance, we can understand on the principle of inheritance, how it is that the thrush of South America lines its nest with mud, in the same peculiar manner as does our British thrush: how it is that the male wrens (Troglodytes) of North America, build "cock-nests," to roost in, like the males of our distinct Kitty-wrens,--a habit wholly unlike that of {244} any other known bird. Finally, it may not be a logical deduction, but to my imagination it is far more satisfactory to look at such instincts as the young cuckoo ejecting its foster-brothers,--ants making slaves,--the larvae of ichneumonidæ feeding within the live bodies of caterpillars,--not as specially endowed or created instincts, but as small consequences of one general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die. * * * * * {245} CHAPTER VIII. HYBRIDISM. Distinction between the sterility of first crosses and of hybrids--Sterility various in degree, not universal, affected by close interbreeding, removed by domestication--Laws governing the sterility of hybrids--Sterility not a special endowment, but incidental on other differences--Causes of the sterility of first crosses and of hybrids--Parallelism between the effects of changed conditions of life and crossing--Fertility of varieties when crossed and of their mongrel offspring not universal--Hybrids and mongrels compared independently of their fertility--Summary. The view generally entertained by naturalists is that species, when intercrossed, have been specially endowed with the quality of sterility, in order to prevent the confusion of all organic forms. This view certainly seems at first probable, for species within the same country could hardly have kept distinct had they been capable of crossing freely. The importance of the fact that hybrids are very generally sterile, has, I think, been much underrated by some late writers. On the theory of natural selection the case is especially important, inasmuch as the sterility of hybrids could not possibly be of any advantage to them, and therefore could not have been acquired by the continued preservation of successive profitable degrees of sterility. I hope, however, to be able to show that sterility is not a specially acquired or endowed quality, but is incidental on other acquired differences. In treating this subject, two classes of facts, to a large extent fundamentally different, have generally been confounded together; namely, the sterility of two species {246} when first crossed, and the sterility of the hybrids produced from them. Pure species have of course their organs of reproduction in a perfect condition, yet when intercrossed they produce either few or no offspring. Hybrids, on the other hand, have their reproductive organs functionally impotent, as may be clearly seen in the state of the male element in both plants and animals; though the organs themselves are perfect in structure, as far as the microscope reveals. In the first case the two sexual elements which go to form the embryo are perfect; in the second case they are either not at all developed, or are imperfectly developed. This distinction is important, when the cause of the sterility, which is common to the two cases, has to be considered. The distinction has probably been slurred over, owing to the sterility in both cases being looked on as a special endowment, beyond the province of our reasoning powers. The fertility of varieties, that is of the forms known or believed to have descended from common parents, when intercrossed, and likewise the fertility of their mongrel offspring, is, on my theory, of equal importance with the sterility of species; for it seems to make a broad and clear distinction between varieties and species. First, for the sterility of species when crossed and of their hybrid offspring. It is impossible to study the several memoirs and works of those two conscientious and admirable observers, Kölreuter and Gärtner, who almost devoted their lives to this subject, without being deeply impressed with the high generality of some degree of sterility. Kölreuter makes the rule universal; but then he cuts the knot, for in ten cases in which he found two forms, considered by most authors as distinct species, quite fertile together, he unhesitatingly ranks {247} them as varieties. Gärtner, also, makes the rule equally universal; and he disputes the entire fertility of Kölreuter's ten cases. But in these and in many other cases, Gärtner is obliged carefully to count the seeds, in order to show that there is any degree of sterility. He always compares the maximum number of seeds produced by two species when crossed and by their hybrid offspring, with the average number produced by both pure parent-species in a state of nature. But a serious cause of error seems to me to be here introduced: a plant to be hybridised must be castrated, and, what is often more important, must be secluded in order to prevent pollen being brought to it by insects from other plants. Nearly all the plants experimentised on by Gärtner were potted, and apparently were kept in a chamber in his house. That these processes are often injurious to the fertility of a plant cannot be doubted; for Gärtner gives in his table about a score of cases of plants which he castrated, and artificially fertilised with their own pollen, and (excluding all cases such as the Leguminosæ, in which there is an acknowledged difficulty in the manipulation) half of these twenty plants had their fertility in some degree impaired. Moreover, as Gärtner during several years repeatedly crossed the primrose and cowslip, which we have such good reason to believe to be varieties, and only once or twice succeeded in getting fertile seed; as he found the common red and blue pimpernels (Anagallis arvensis and coerulea), which the best botanists rank as varieties, absolutely sterile together; and as he came to the same conclusion in several other analogous cases; it seems to me that we may well be permitted to doubt whether many other species are really so sterile, when intercrossed, as Gärtner believes. {248} It is certain, on the one hand, that the sterility of various species when crossed is so different in degree and graduates away so insensibly, and, on the other hand, that the fertility of pure species is so easily affected by various circumstances, that for all practical purposes it is most difficult to say where perfect fertility ends and sterility begins. I think no better evidence of this can be required than that the two most experienced observers who have ever lived, namely, Kölreuter and Gärtner, should have arrived at diametrically opposite conclusions in regard to the very same species. It is also most instructive to compare--but I have not space here to enter on details--the evidence advanced by our best botanists on the question whether certain doubtful forms should be ranked as species or varieties, with the evidence from fertility adduced by different hybridisers, or by the same author, from experiments made during different years. It can thus be shown that neither sterility nor fertility affords any clear distinction between species and varieties; but that the evidence from this source graduates away, and is doubtful in the same degree as is the evidence derived from other constitutional and structural differences. In regard to the sterility of hybrids in successive generations; though Gärtner was enabled to rear some hybrids, carefully guarding them from a cross with either pure parent, for six or seven, and in one case for ten generations, yet he asserts positively that their fertility never increased, but generally greatly decreased. I do not doubt that this is usually the case, and that the fertility often suddenly decreases in the first few generations. Nevertheless I believe that in all these experiments the fertility has been diminished by an independent cause, namely, from close interbreeding. I have collected so large a body of facts, showing {249} that close interbreeding lessens fertility, and, on the other hand, that an occasional cross with a distinct individual or variety increases fertility, that I cannot doubt the correctness of this almost universal belief amongst breeders. Hybrids are seldom raised by experimentalists in great numbers; and as the parent-species, or other allied hybrids, generally grow in the same garden, the visits of insects must be carefully prevented during the flowering season: hence hybrids will generally be fertilised during each generation by their own individual pollen; and I am convinced that this would be injurious to their fertility, already lessened by their hybrid origin. I am strengthened in this conviction by a remarkable statement repeatedly made by Gärtner, namely, that if even the less fertile hybrids be artificially fertilised with hybrid pollen of the same kind, their fertility, notwithstanding the frequent ill effects of manipulation, sometimes decidedly increases, and goes on increasing. Now, in artificial fertilisation pollen is as often taken by chance (as I know from my own experience) from the anthers of another flower, as from the anthers of the flower itself which is to be fertilised; so that a cross between two flowers, though probably on the same plant, would be thus effected. Moreover, whenever complicated experiments are in progress, so careful an observer as Gärtner would have castrated his hybrids, and this would have insured in each generation a cross with a pollen from a distinct flower, either from the same plant or from another plant of the same hybrid nature. And thus, the strange fact of the increase of fertility in the successive generations of _artificially fertilised_ hybrids may, I believe, be accounted for by close interbreeding having been avoided. Now let us turn to the results arrived at by the third most experienced hybridiser, namely, the Hon. and {250} Rev. W. Herbert. He is as emphatic in his conclusion that some hybrids are perfectly fertile--as fertile as the pure parent-species--as are Kölreuter and Gärtner that some degree of sterility between distinct species is a universal law of nature. He experimentised on some of the very same species as did Gärtner. The difference in their results may, I think, be in part accounted for by Herbert's great horticultural skill, and by his having hothouses at his command. Of his many important statements I will here give only a single one as an example, namely, that "every ovule in a pod of Crinum capense fertilised by C. revolutum produced a plant, which (he says) I never saw to occur in a case of its natural fecundation." So that we here have perfect, or even more than commonly perfect, fertility in a first cross between two distinct species. This case of the Crinum leads me to refer to a most singular fact, namely, that there are individual plants of certain species of Lobelia and of some other genera, which can be far more easily fertilised by the pollen of another and distinct species, than by their own pollen; and all the individuals of nearly all the species of Hippeastrum seem to be in this predicament. For these plants have been found to yield seed to the pollen of a distinct species, though quite sterile with their own pollen, notwithstanding that their own pollen was found to be perfectly good, for it fertilised distinct species. So that certain individual plants and all the individuals of certain species can actually be hybridised much more readily than they can be self-fertilised! For instance, a bulb of Hippeastrum aulicum produced four flowers; three were fertilised by Herbert with their own pollen, and the fourth was subsequently fertilised by the pollen of a compound hybrid descended from three other and distinct {251} species: the result was that "the ovaries of the three first flowers soon ceased to grow, and after a few days perished entirely, whereas the pod impregnated by the pollen of the hybrid made vigorous growth and rapid progress to maturity, and bore good seed, which vegetated freely." In a letter to me, in 1839, Mr. Herbert told me that he had then tried the experiment during five years, and he continued to try it during several subsequent years, and always with the same result. This result has, also, been confirmed by other observers in the case of Hippeastrum with its sub-genera, and in the case of some other genera, as Lobelia, Passiflora and Verbascum. Although the plants in these experiments appeared perfectly healthy, and although both the ovules and pollen of the same flower were perfectly good with respect to other species, yet as they were functionally imperfect in their mutual self-action, we must infer that the plants were in an unnatural state. Nevertheless these facts show on what slight and mysterious causes the lesser or greater fertility of species when crossed, in comparison with the same species when self-fertilised, sometimes depends. The practical experiments of horticulturists, though not made with scientific precision, deserve some notice. It is notorious in how complicated a manner the species of Pelargonium, Fuchsia, Calceolaria, Petunia, Rhododendron, &c., have been crossed, yet many of these hybrids seed freely. For instance, Herbert asserts that a hybrid from Calceolaria integrifolia and plantaginea, species most widely dissimilar in general habit, "reproduced itself as perfectly as if it had been a natural species from the mountains of Chile." I have taken some pains to ascertain the degree of fertility of some of the complex crosses of Rhododendrons, and I am assured that many of them {252} are perfectly fertile. Mr. C. Noble, for instance, informs me that he raises stocks for grafting from a hybrid between Rhod. Ponticum and Catawbiense, and that this hybrid "seeds as freely as it is possible to imagine." Had hybrids, when fairly treated, gone on decreasing in fertility in each successive generation, as Gärtner believes to be the case, the fact would have been notorious to nurserymen. Horticulturists raise large beds of the same hybrids, and such alone are fairly treated, for by insect agency the several individuals of the same hybrid variety are allowed to freely cross with each other, and the injurious influence of close interbreeding is thus prevented. Any one may readily convince himself of the efficiency of insect-agency by examining the flowers of the more sterile kinds of hybrid rhododendrons, which produce no pollen, for he will find on their stigmas plenty of pollen brought from other flowers. In regard to animals, much fewer experiments have been carefully tried than with plants. If our systematic arrangements can be trusted, that is if the genera of animals are as distinct from each other, as are the genera of plants, then we may infer that animals more widely separated in the scale of nature can be more easily crossed than in the case of plants; but the hybrids themselves are, I think, more sterile. I doubt whether any case of a perfectly fertile hybrid animal can be considered as thoroughly well authenticated. It should, however, be borne in mind that, owing to few animals breeding freely under confinement, few experiments have been fairly tried: for instance, the canary-bird has been crossed with nine other finches, but as not one of these nine species breeds freely in confinement, we have no right to expect that the first crosses between them and the canary, or that their hybrids, {253} should be perfectly fertile. Again, with respect to the fertility in successive generations of the more fertile hybrid animals, I hardly know of an instance in which two families of the same hybrid have been raised at the same time from different parents, so as to avoid the ill effects of close interbreeding. On the contrary, brothers and sisters have usually been crossed in each successive generation, in opposition to the constantly repeated admonition of every breeder. And in this case, it is not at all surprising that the inherent sterility in the hybrids should have gone on increasing. If we were to act thus, and pair brothers and sisters in the case of any pure animal, which from any cause had the least tendency to sterility, the breed would assuredly be lost in a very few generations. Although I do not know of any thoroughly well-authenticated cases of perfectly fertile hybrid animals, I have some reason to believe that the hybrids from Cervulus vaginalis and Reevesii, and from Phasianus colchicus with P. torquatus and with P. versicolor are perfectly fertile. There is no doubt that these three pheasants, namely, the common, the true ring-necked, and the Japan, intercross, and are becoming blended together in the woods of several parts of England. The hybrids from the common and Chinese geese (A. cygnoides), species which are so different that they are generally ranked in distinct genera, have often bred in this country with either pure parent, and in one single instance they have bred _inter se_. This was effected by Mr. Eyton, who raised two hybrids from the same parents but from different hatches; and from these two birds he raised no less than eight hybrids (grandchildren of the pure geese) from one nest. In India, however, these cross-bred geese must be far more fertile; for I am assured by two eminently capable judges, namely {254} Mr. Blyth and Capt. Hutton, that whole flocks of these crossed geese are kept in various parts of the country; and as they are kept for profit, where neither pure parent-species exists, they must certainly be highly fertile. A doctrine which originated with Pallas, has been largely accepted by modern naturalists; namely, that most of our domestic animals have descended from two or more wild species, since commingled by intercrossing. On this view, the aboriginal species must either at first have produced quite fertile hybrids, or the hybrids must have become in subsequent generations quite fertile under domestication. This latter alternative seems to me the most probable, and I am inclined to believe in its truth, although it rests on no direct evidence. I believe, for instance, that our dogs have descended from several wild stocks; yet, with perhaps the exception of certain indigenous domestic dogs of South America, all are quite fertile together; and analogy makes me greatly doubt, whether the several aboriginal species would at first have freely bred together and have produced quite fertile hybrids. So again there is reason to believe that our European and the humped Indian cattle are quite fertile together; but from facts communicated to me by Mr. Blyth, I think they must be considered as distinct species. On this view of the origin of many of our domestic animals, we must either give up the belief of the almost universal sterility of distinct species of animals when crossed; or we must look at sterility, not as an indelible characteristic, but as one capable of being removed by domestication. Finally, looking to all the ascertained facts on the intercrossing of plants and animals, it may be concluded that some degree of sterility, both in first crosses {255} and in hybrids, is an extremely general result; but that it cannot, under our present state of knowledge, be considered as absolutely universal. _Laws governing the Sterility of first Crosses and of Hybrids._--We will now consider a little more in detail the circumstances and rules governing the sterility of first crosses and of hybrids. Our chief object will be to see whether or not the rules indicate that species have specially been endowed with this quality, in order to prevent their crossing and blending together in utter confusion. The following rules and conclusions are chiefly drawn up from Gärtner's admirable work on the hybridisation of plants. I have taken much pains to ascertain how far the rules apply to animals, and considering how scanty our knowledge is in regard to hybrid animals, I have been surprised to find how generally the same rules apply to both kingdoms. It has been already remarked, that the degree of fertility, both of first crosses and of hybrids, graduates from zero to perfect fertility. It is surprising in how many curious ways this gradation can be shown to exist; but only the barest outline of the facts can here be given. When pollen from a plant of one family is placed on the stigma of a plant of a distinct family, it exerts no more influence than so much inorganic dust. From this absolute zero of fertility, the pollen of different species of the same genus applied to the stigma of some one species, yields a perfect gradation in the number of seeds produced, up to nearly complete or even quite complete fertility; and, as we have seen, in certain abnormal cases, even to an excess of fertility, beyond that which the plant's own pollen will produce. So in hybrids themselves, there are some which never have produced, and probably never would produce, even {256} with the pollen of either pure parent, a single fertile seed: but in some of these cases a first trace of fertility may be detected, by the pollen of one of the pure parent-species causing the flower of the hybrid to wither earlier than it otherwise would have done; and the early withering of the flower is well known to be a sign of incipient fertilisation. From this extreme degree of sterility we have self-fertilised hybrids producing a greater and greater number of seeds up to perfect fertility. Hybrids from two species which are very difficult to cross, and which rarely produce any offspring, are generally very sterile; but the parallelism between the difficulty of making a first cross, and the sterility of the hybrids thus produced--two classes of facts which are generally confounded together--is by no means strict. There are many cases, in which two pure species can be united with unusual facility, and produce numerous hybrid-offspring, yet these hybrids are remarkably sterile. On the other hand, there are species which can be crossed very rarely, or with extreme difficulty, but the hybrids, when at last produced, are very fertile. Even within the limits of the same genus, for instance in Dianthus, these two opposite cases occur. The fertility, both of first crosses and of hybrids, is more easily affected by unfavourable conditions, than is the fertility of pure species. But the degree of fertility is likewise innately variable; for it is not always the same when the same two species are crossed under the same circumstances, but depends in part upon the constitution of the individuals which happen to have been chosen for the experiment. So it is with hybrids, for their degree of fertility is often found to differ greatly in the several individuals raised from seed out of the same capsule and exposed to exactly the same conditions. {257} By the term systematic affinity is meant, the resemblance between species in structure and in constitution, more especially in the structure of parts which are of high physiological importance and which differ little in the allied species. Now the fertility of first crosses between species, and of the hybrids produced from them, is largely governed by their systematic affinity. This is clearly shown by hybrids never having been raised between species ranked by systematists in distinct families; and on the other hand, by very closely allied species generally uniting with facility. But the correspondence between systematic affinity and the facility of crossing is by no means strict. A multitude of cases could be given of very closely allied species which will not unite, or only with extreme difficulty; and on the other hand of very distinct species which unite with the utmost facility. In the same family there may be a genus, as Dianthus, in which very many species can most readily be crossed; and another genus, as Silene, in which the most persevering efforts have failed to produce between extremely close species a single hybrid. Even within the limits of the same genus, we meet with this same difference; for instance, the many species of Nicotiana have been more largely crossed than the species of almost any other genus; but Gärtner found that N. acuminata, which is not a particularly distinct species, obstinately failed to fertilise, or to be fertilised by, no less than eight other species of Nicotiana. Very many analogous facts could be given. No one has been able to point out what kind, or what amount, of difference in any recognisable character is sufficient to prevent two species crossing. It can be shown that plants most widely different in habit and general appearance, and having strongly marked {258} differences in every part of the flower, even in the pollen, in the fruit, and in the cotyledons, can be crossed. Annual and perennial plants, deciduous and evergreen trees, plants inhabiting different stations and fitted for extremely different climates, can often be crossed with ease. By a reciprocal cross between two species, I mean the case, for instance, of a stallion-horse being first crossed with a female-ass, and then a male-ass with a mare: these two species may then be said to have been reciprocally crossed. There is often the widest possible difference in the facility of making reciprocal crosses. Such cases are highly important, for they prove that the capacity in any two species to cross is often completely independent of their systematic affinity, or of any recognisable difference in their whole organisation. On the other hand, these cases clearly show that the capacity for crossing is connected with constitutional differences imperceptible by us, and confined to the reproductive system. This difference in the result of reciprocal crosses between the same two species was long ago observed by Kölreuter. To give an instance: Mirabilis jalapa can easily be fertilised by the pollen of M. longiflora, and the hybrids thus produced are sufficiently fertile; but Kölreuter tried more than two hundred times, during eight following years, to fertilise reciprocally M. longiflora with the pollen of M. jalapa, and utterly failed. Several other equally striking cases could be given. Thuret has observed the same fact with certain sea-weeds or Fuci. Gärtner, moreover, found that this difference of facility in making reciprocal crosses is extremely common in a lesser degree. He has observed it even between forms so closely related (as Matthiola annua and glabra) that many botanists rank them only as varieties. It is also a remarkable fact, that hybrids raised from reciprocal crosses, though {259} of course compounded of the very same two species, the one species having first been used as the father and then as the mother, generally differ in fertility in a small, and occasionally in a high degree. Several other singular rules could be given from Gärtner: for instance, some species have a remarkable power of crossing with other species; other species of the same genus have a remarkable power of impressing their likeness on their hybrid offspring; but these two powers do not at all necessarily go together. There are certain hybrids which instead of having, as is usual, an intermediate character between their two parents, always closely resemble one of them; and such hybrids, though externally so like one of their pure parent-species, are with rare exceptions extremely sterile. So again amongst hybrids which are usually intermediate in structure between their parents, exceptional and abnormal individuals sometimes are born, which closely resemble one of their pure parents; and these hybrids are almost always utterly sterile, even when the other hybrids raised from seed from the same capsule have a considerable degree of fertility. These facts show how completely fertility in the hybrid is independent of its external resemblance to either pure parent. Considering the several rules now given, which govern the fertility of first crosses and of hybrids, we see that when forms, which must be considered as good and distinct species, are united, their fertility graduates from zero to perfect fertility, or even to fertility under certain conditions in excess. That their fertility, besides being eminently susceptible to favourable and unfavourable conditions, is innately variable. That it is by no means always the same in degree in the first cross and in the hybrids produced {260} from this cross. That the fertility of hybrids is not related to the degree in which they resemble in external appearance either parent. And lastly, that the facility of making a first cross between any two species is not always governed by their systematic affinity or degree of resemblance to each other. This latter statement is clearly proved by reciprocal crosses between the same two species, for according as the one species or the other is used as the father or the mother, there is generally some difference, and occasionally the widest possible difference, in the facility of effecting an union. The hybrids, moreover, produced from reciprocal crosses often differ in fertility. Now do these complex and singular rules indicate that species have been endowed with sterility simply to prevent their becoming confounded in nature? I think not. For why should the sterility be so extremely different in degree, when various species are crossed, all of which we must suppose it would be equally important to keep from blending together? Why should the degree of sterility be innately variable in the individuals of the same species? Why should some species cross with facility, and yet produce very sterile hybrids; and other species cross with extreme difficulty, and yet produce fairly fertile hybrids? Why should there often be so great a difference in the result of a reciprocal cross between the same two species? Why, it may even be asked, has the production of hybrids been permitted? to grant to species the special power of producing hybrids, and then to stop their further propagation by different degrees of sterility, not strictly related to the facility of the first union between their parents, seems to be a strange arrangement. The foregoing rules and facts, on the other hand, {261} appear to me clearly to indicate that the sterility both of first crosses and of hybrids is simply incidental or dependent on unknown differences, chiefly in the reproductive systems, of the species which are crossed. The differences being of so peculiar and limited a nature, that, in reciprocal crosses between two species the male sexual element of the one will often freely act on the female sexual element of the other, but not in a reversed direction. It will be advisable to explain a little more fully by an example what I mean by sterility being incidental on other differences, and not a specially endowed quality. As the capacity of one plant to be grafted or budded on another is so entirely unimportant for its welfare in a state of nature, I presume that no one will suppose that this capacity is a _specially_ endowed quality, but will admit that it is incidental on differences in the laws of growth of the two plants. We can sometimes see the reason why one tree will not take on another, from differences in their rate of growth, in the hardness of their wood, in the period of the flow or nature of their sap, &c.; but in a multitude of cases we can assign no reason whatever. Great diversity in the size of two plants, one being woody and the other herbaceous, one being evergreen and the other deciduous, and adaptation to widely different climates, does not always prevent the two grafting together. As in hybridisation, so with grafting, the capacity is limited by systematic affinity, for no one has been able to graft trees together belonging to quite distinct families; and, on the other hand, closely allied species, and varieties of the same species, can usually, but not invariably, be grafted with ease. But this capacity, as in hybridisation, is by no means absolutely governed by systematic affinity. Although many distinct genera within the same family have been grafted {262} together, in other cases species of the same genus will not take on each other. The pear can be grafted far more readily on the quince, which is ranked as a distinct genus, than on the apple, which is a member of the same genus. Even different varieties of the pear take with different degrees of facility on the quince; so do different varieties of the apricot and peach on certain varieties of the plum. As Gärtner found that there was sometimes an innate difference in different _individuals_ of the same two species in crossing; so Sagaret believes this to be the case with different individuals of the same two species in being grafted together. As in reciprocal crosses, the facility of effecting an union is often very far from equal, so it sometimes is in grafting; the common gooseberry, for instance, cannot be grafted on the currant, whereas the currant will take, though with difficulty, on the gooseberry. We have seen that the sterility of hybrids, which have their reproductive organs in an imperfect condition, is a very different case from the difficulty of uniting two pure species, which have their reproductive organs perfect; yet these two distinct cases run to a certain extent parallel. Something analogous occurs in grafting; for Thouin found that three species of Robinia, which seeded freely on their own roots, and which could be grafted with no great difficulty on another species, when thus grafted were rendered barren. On the other hand, certain species of Sorbus, when grafted on other species, yielded twice as much fruit as when on their own roots. We are reminded by this latter fact of the extraordinary case of Hippeastrum, Lobelia, &c., which seeded much more freely when fertilised with the pollen of distinct species, than when self-fertilised with their own pollen. {263} We thus see, that although there is a clear and fundamental difference between the mere adhesion of grafted stocks, and the union of the male and female elements in the act of reproduction, yet that there is a rude degree of parallelism in the results of grafting and of crossing distinct species. And as we must look at the curious and complex laws governing the facility with which trees can be grafted on each other as incidental on unknown differences in their vegetative systems, so I believe that the still more complex laws governing the facility of first crosses, are incidental on unknown differences, chiefly in their reproductive systems. These differences, in both cases, follow to a certain extent, as might have been expected, systematic affinity, by which every kind of resemblance and dissimilarity between organic beings is attempted to be expressed. The facts by no means seem to me to indicate that the greater or lesser difficulty of either grafting or crossing together various species has been a special endowment; although in the case of crossing, the difficulty is as important for the endurance and stability of specific forms, as in the case of grafting it is unimportant for their welfare. _Causes of the Sterility of first Crosses and of Hybrids._--We may now look a little closer at the probable causes of the sterility of first crosses and of hybrids. These two cases are fundamentally different, for, as just remarked, in the union of two pure species the male and female sexual elements are perfect, whereas in hybrids they are imperfect. Even in first crosses, the greater or lesser difficulty in effecting a union apparently depends on several distinct causes. There must sometimes be a physical impossibility in the male element reaching the ovule, as would be the case with a plant {264} having a pistil too long for the pollen-tubes to reach the ovarium. It has also been observed that when pollen of one species is placed on the stigma of a distantly allied species, though the pollen-tubes protrude, they do not penetrate the stigmatic surface. Again, the male element may reach the female element, but be incapable of causing an embryo to be developed, as seems to have been the case with some of Thuret's experiments on Fuci. No explanation can be given of these facts, any more than why certain trees cannot be grafted on others. Lastly, an embryo may be developed, and then perish at an early period. This latter alternative has not been sufficiently attended to; but I believe, from observations communicated to me by Mr. Hewitt, who has had great experience in hybridising gallinaceous birds, that the early death of the embryo is a very frequent cause of sterility in first crosses. I was at first very unwilling to believe in this view; as hybrids, when once born, are generally healthy and long-lived, as we see in the case of the common mule. Hybrids, however, are differently circumstanced before and after birth: when born and living in a country where their two parents can live, they are generally placed under suitable conditions of life. But a hybrid partakes of only half of the nature and constitution of its mother, and therefore before birth, as long as it is nourished within its mother's womb or within the egg or seed produced by the mother, it may be exposed to conditions in some degree unsuitable, and consequently be liable to perish at an early period; more especially as all very young beings seem eminently sensitive to injurious or unnatural conditions of life. In regard to the sterility of hybrids, in which the sexual elements are imperfectly developed, the case is {265} very different. I have more than once alluded to a large body of facts, which I have collected, showing that when animals and plants are removed from their natural conditions, they are extremely liable to have their reproductive systems seriously affected. This, in fact, is the great bar to the domestication of animals. Between the sterility thus superinduced and that of hybrids, there are many points of similarity. In both cases the sterility is independent of general health, and is often accompanied by excess of size or great luxuriance. In both cases, the sterility occurs in various degrees; in both, the male element is the most liable to be affected; but sometimes the female more than the male. In both, the tendency goes to a certain extent with systematic affinity, for whole groups of animals and plants are rendered impotent by the same unnatural conditions; and whole groups of species tend to produce sterile hybrids. On the other hand, one species in a group will sometimes resist great changes of conditions with unimpaired fertility; and certain species in a group will produce unusually fertile hybrids. No one can tell, till he tries, whether any particular animal will breed under confinement or any exotic plant seed freely under culture; nor can he tell, till he tries, whether any two species of a genus will produce more or less sterile hybrids. Lastly, when organic beings are placed during several generations under conditions not natural to them, they are extremely liable to vary, which is due, as I believe, to their reproductive systems having been specially affected, though in a lesser degree than when sterility ensues. So it is with hybrids, for hybrids in successive generations are eminently liable to vary, as every experimentalist has observed. Thus we see that when organic beings are placed under new and unnatural conditions, and when hybrids {266} are produced by the unnatural crossing of two species, the reproductive system, independently of the general state of health, is affected by sterility in a very similar manner. In the one case, the conditions of life have been disturbed, though often in so slight a degree as to be inappreciable by us; in the other case, or that of hybrids, the external conditions have remained the same, but the organisation has been disturbed by two different structures and constitutions having been blended into one. For it is scarcely possible that two organisations should be compounded into one, without some disturbance occurring in the development, or periodical action, or mutual relation of the different parts and organs one to another, or to the conditions of life. When hybrids are able to breed _inter se_, they transmit to their offspring from generation to generation the same compounded organisation, and hence we need not be surprised that their sterility, though in some degree variable, rarely diminishes. It must, however, be confessed that we cannot understand, excepting on vague hypotheses, several facts with respect to the sterility of hybrids; for instance, the unequal fertility of hybrids produced from reciprocal crosses; or the increased sterility in those hybrids which occasionally and exceptionally resemble closely either pure parent. Nor do I pretend that the foregoing remarks go to the root of the matter: no explanation is offered why an organism, when placed under unnatural conditions, is rendered sterile. All that I have attempted to show, is that in two cases, in some respects allied, sterility is the common result,--in the one case from the conditions of life having been disturbed, in the other case from the organisation having been disturbed by two organisations having been compounded into one. It may seem fanciful, but I suspect that a similar {267} parallelism extends to an allied yet very different class of facts. It is an old and almost universal belief, founded, I think, on a considerable body of evidence, that slight changes in the conditions of life are beneficial to all living things. We see this acted on by farmers and gardeners in their frequent exchanges of seed, tubers, &c., from one soil or climate to another, and back again. During the convalescence of animals, we plainly see that great benefit is derived from almost any change in the habits of life. Again, both with plants and animals, there is abundant evidence, that a cross between very distinct individuals of the same species, that is between members of different strains or sub-breeds, gives vigour and fertility to the offspring. I believe, indeed, from the facts alluded to in our fourth chapter, that a certain amount of crossing is indispensable even with hermaphrodites; and that close interbreeding continued during several generations between the nearest relations, especially if these be kept under the same conditions of life, always induces weakness and sterility in the progeny. Hence it seems that, on the one hand, slight changes in the conditions of life benefit all organic beings, and on the other hand, that slight crosses, that is crosses between the males and females of the same species which have varied and become slightly different, give vigour and fertility to the offspring. But we have seen that greater changes, or changes of a particular nature, often render organic beings in some degree sterile; and that greater crosses, that is crosses between males and females which have become widely or specifically different, produce hybrids which are generally sterile in some degree. I cannot persuade myself that this parallelism is an accident or an illusion. Both series of facts seem to be connected together by some {268} common but unknown bond, which is essentially related to the principle of life. _Fertility of Varieties when crossed, and of their Mongrel offspring._--It may be urged, as a most forcible argument, that there must be some essential distinction between species and varieties, and that there must be some error in all the foregoing remarks, inasmuch as varieties, however much they may differ from each other in external appearance, cross with perfect facility, and yield perfectly fertile offspring. I fully admit that this is almost invariably the case. But if we look to varieties produced under nature, we are immediately involved in hopeless difficulties; for if two hitherto reputed varieties be found in any degree sterile together, they are at once ranked by most naturalists as species. For instance, the blue and red pimpernel, the primrose and cowslip, which are considered by many of our best botanists as varieties, are said by Gärtner not to be quite fertile when crossed, and he consequently ranks them as undoubted species. If we thus argue in a circle, the fertility of all varieties produced under nature will assuredly have to be granted. If we turn to varieties, produced, or supposed to have been produced, under domestication, we are still involved in doubt. For when it is stated, for instance, that the German Spitz dog unites more easily than other dogs with foxes, or that certain South American indigenous domestic dogs do not readily cross with European dogs, the explanation which will occur to every one, and probably the true one, is that these dogs have descended from several aboriginally distinct species. Nevertheless the perfect fertility of so many domestic varieties, differing widely from each other in appearance, for instance of the pigeon or of the cabbage, is {269} a remarkable fact; more especially when we reflect how many species there are, which, though resembling each other most closely, are utterly sterile when intercrossed. Several considerations, however, render the fertility of domestic varieties less remarkable than at first appears. It can, in the first place, be clearly shown that mere external dissimilarity between two species does not determine their greater or lesser degree of sterility when crossed; and we may apply the same rule to domestic varieties. In the second place, some eminent naturalists believe that a long course of domestication tends to eliminate sterility in the successive generations of hybrids which were at first only slightly sterile; and if this be so, we surely ought not to expect to find sterility both appearing and disappearing under nearly the same conditions of life. Lastly, and this seems to me by far the most important consideration, new races of animals and plants are produced under domestication by man's methodical and unconscious power of selection, for his own use and pleasure: he neither wishes to select, nor could select, slight differences in the reproductive system, or other constitutional differences correlated with the reproductive system. He supplies his several varieties with the same food; treats them in nearly the same manner, and does not wish to alter their general habits of life. Nature acts uniformly and slowly during vast periods of time on the whole organisation, in any way which may be for each creature's own good; and thus she may, either directly, or more probably indirectly, through correlation, modify the reproductive system in the several descendants from any one species. Seeing this difference in the process of selection, as carried on by man and nature, we need not be surprised at some difference in the result. I have as yet spoken as if the varieties of the same {270} species were invariably fertile when intercrossed. But it seems to me impossible to resist the evidence of the existence of a certain amount of sterility in the few following cases, which I will briefly abstract. The evidence is at least as good as that from which we believe in the sterility of a multitude of species. The evidence is, also, derived from hostile witnesses, who in all other cases consider fertility and sterility as safe criterions of specific distinction. Gärtner kept during several years a dwarf kind of maize with yellow seeds, and a tall variety with red seeds, growing near each other in his garden; and although these plants have separated sexes, they never naturally crossed. He then fertilised thirteen flowers of the one with the pollen of the other; but only a single head produced any seed, and this one head produced only five grains. Manipulation in this case could not have been injurious, as the plants have separated sexes. No one, I believe, has suspected that these varieties of maize are distinct species; and it is important to notice that the hybrid plants thus raised were themselves _perfectly_ fertile; so that even Gärtner did not venture to consider the two varieties as specifically distinct. Girou de Buzareingues crossed three varieties of gourd, which like the maize has separated sexes, and he asserts that their mutual fertilisation is by so much the less easy as their differences are greater. How far these experiments may be trusted, I know not; but the forms experimentised on, are ranked by Sagaret, who mainly founds his classification by the test of infertility, as varieties. The following case is far more remarkable, and seems at first quite incredible; but it is the result of an astonishing number of experiments made during many years on nine species of Verbascum, by so good an observer {271} and so hostile a witness, as Gärtner: namely, that yellow and white varieties of the same species of Verbascum when intercrossed produce less seed, than do either coloured varieties when fertilised with pollen from their own coloured flowers. Moreover, he asserts that when yellow and white varieties of one species are crossed with yellow and white varieties of a _distinct_ species, more seed is produced by the crosses between the similarly coloured flowers, than between those which are differently coloured. Yet these varieties of Verbascum present no other difference besides the mere colour of the flower; and one variety can sometimes be raised from the seed of the other. From observations which I have made on certain varieties of hollyhock, I am inclined to suspect that they present analogous facts. Kölreuter, whose accuracy has been confirmed by every subsequent observer, has proved the remarkable fact, that one variety of the common tobacco is more fertile, when crossed with a widely distinct species, than are the other varieties. He experimentised on five forms, which are commonly reputed to be varieties, and which he tested by the severest trial, namely, by reciprocal crosses, and he found their mongrel offspring perfectly fertile. But one of these five varieties, when used either as father or mother, and crossed with the Nicotiana glutinosa, always yielded hybrids not so sterile as those which were produced from the four other varieties when crossed with N. glutinosa. Hence the reproductive system of this one variety must have been in some manner and in some degree modified. From these facts; from the great difficulty of ascertaining the infertility of varieties in a state of nature, for a supposed variety if infertile in any degree would generally be ranked as species; from man selecting only {272} external characters in the production of the most distinct domestic varieties, and from not wishing or being able to produce recondite and functional differences in the reproductive system; from these several considerations and facts, I do not think that the very general fertility of varieties can be proved to be of universal occurrence, or to form a fundamental distinction between varieties and species. The general fertility of varieties does not seem to me sufficient to overthrow the view which I have taken with respect to the very general, but not invariable, sterility of first crosses and of hybrids, namely, that it is not a special endowment, but is incidental on slowly acquired modifications, more especially in the reproductive systems of the forms which are crossed. _Hybrids and Mongrels compared, independently of their fertility._--Independently of the question of fertility, the offspring of species when crossed and of varieties when crossed may be compared in several other respects. Gärtner, whose strong wish was to draw a marked line of distinction between species and varieties, could find very few and, as it seems to me, quite unimportant differences between the so-called hybrid offspring of species, and the so-called mongrel offspring of varieties. And, on the other hand, they agree most closely in very many important respects. I shall here discuss this subject with extreme brevity. The most important distinction is, that in the first generation mongrels are more variable than hybrids; but Gärtner admits that hybrids from species which have long been cultivated are often variable in the first generation; and I have myself seen striking instances of this fact. Gärtner further admits that hybrids between very closely allied species are more variable {273} than those from very distinct species; and this shows that the difference in the degree of variability graduates away. When mongrels and the more fertile hybrids are propagated for several generations an extreme amount of variability in their offspring is notorious; but some few cases both of hybrids and mongrels long retaining uniformity of character could be given. The variability, however, in the successive generations of mongrels is, perhaps, greater than in hybrids. This greater variability of mongrels than of hybrids does not seem to me at all surprising. For the parents of mongrels are varieties, and mostly domestic varieties (very few experiments having been tried on natural varieties), and this implies in most cases that there has been recent variability; and therefore we might expect that such variability would often continue and be superadded to that arising from the mere act of crossing. The slight degree of variability in hybrids from the first cross or in the first generation, in contrast with their extreme variability in the succeeding generations, is a curious fact and deserves attention. For it bears on and corroborates the view which I have taken on the cause of ordinary variability; namely, that it is due to the reproductive system being eminently sensitive to any change in the conditions of life, being thus often rendered either impotent or at least incapable of its proper function of producing offspring identical with the parent-form. Now hybrids in the first generation are descended from species (excluding those long cultivated) which have not had their reproductive systems in any way affected, and they are not variable; but hybrids themselves have their reproductive systems seriously affected, and their descendants are highly variable. But to return to our comparison of mongrels and {274} hybrids: Gärtner states that mongrels are more liable than hybrids to revert to either parent-form; but this, if it be true, is certainly only a difference in degree. Gärtner further insists that when any two species, although most closely allied to each other, are crossed with a third species, the hybrids are widely different from each other; whereas if two very distinct varieties of one species are crossed with another species, the hybrids do not differ much. But this conclusion, as far as I can make out, is founded on a single experiment; and seems directly opposed to the results of several experiments made by Kölreuter. These alone are the unimportant differences, which Gärtner is able to point out, between hybrid and mongrel plants. On the other hand, the resemblance in mongrels and in hybrids to their respective parents, more especially in hybrids produced from nearly related species, follows according to Gärtner the same laws. When two species are crossed, one has sometimes a prepotent power of impressing its likeness on the hybrid; and so I believe it to be with varieties of plants. With animals one variety certainly often has this prepotent power over another variety. Hybrid plants produced from a reciprocal cross, generally resemble each other closely; and so it is with mongrels from a reciprocal cross. Both hybrids and mongrels can be reduced to either pure parent-form, by repeated crosses in successive generations with either parent. These several remarks are apparently applicable to animals; but the subject is here excessively complicated, partly owing to the existence of secondary sexual characters; but more especially owing to prepotency in transmitting likeness running more strongly in one sex than in the other, both when one species is crossed with another, and when, one variety is crossed with {275} another variety. For instance, I think those authors are right, who maintain that the ass has a prepotent power over the horse, so that both the mule and the hinny more resemble the ass than the horse; but that the prepotency runs more strongly in the male-ass than in the female, so that the mule, which is the offspring of the male-ass and mare, is more like an ass, than is the hinny, which is the offspring of the female-ass and stallion. Much stress has been laid by some authors on the supposed fact, that mongrel animals alone are born closely like one of their parents; but it can be shown that this does sometimes occur with hybrids; yet I grant much less frequently with hybrids than with mongrels. Looking to the cases which I have collected of cross-bred animals closely resembling one parent, the resemblances seem chiefly confined to characters almost monstrous in their nature, and which have suddenly appeared--such as albinism, melanism, deficiency of tail or horns, or additional fingers and toes; and do not relate to characters which have been slowly acquired by selection. Consequently, sudden reversions to the perfect character of either parent would be more likely to occur with mongrels, which are descended from varieties often suddenly produced and semi-monstrous in character, than with hybrids, which are descended from species slowly and naturally produced. On the whole I entirely agree with Dr. Prosper Lucas, who, after arranging an enormous body of facts with respect to animals, comes to the conclusion, that the laws of resemblance of the child to its parents are the same, whether the two parents differ much or little from each other, namely in the union of individuals of the same variety, or of different varieties, or of distinct species. Laying aside the question of fertility and sterility, {276} in all other respects there seems to be a general and close similarity in the offspring of crossed species, and of crossed varieties. If we look at species as having been specially created, and at varieties as having been produced by secondary laws, this similarity would be an astonishing fact. But it harmonises perfectly with the view that there is no essential distinction between species and varieties. _Summary of Chapter._--First crosses between forms sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile. The sterility is of all degrees, and is often so slight that the two most careful experimentalists who have ever lived, have come to diametrically opposite conclusions in ranking forms by this test. The sterility is innately variable in individuals of the same species, and is eminently susceptible of favourable and unfavourable conditions. The degree of sterility does not strictly follow systematic affinity, but is governed by several curious and complex laws. It is generally different, and sometimes widely different, in reciprocal crosses between the same two species. It is not always equal in degree in a first cross and in the hybrid produced from this cross. In the same manner as in grafting trees, the capacity of one species or variety to take on another, is incidental on generally unknown differences in their vegetative systems, so in crossing, the greater or less facility of one species to unite with another, is incidental on unknown differences in their reproductive systems. There is no more reason to think that species have been specially endowed with various degrees of sterility to prevent them crossing and blending in nature, than to think that trees have been specially endowed with various and {277} somewhat analogous degrees of difficulty in being grafted together in order to prevent them becoming inarched in our forests. The sterility of first crosses between pure species, which have their reproductive systems perfect, seems to depend on several circumstances; in some cases largely on the early death of the embryo. The sterility of hybrids, which have their reproductive systems imperfect, and which have had this system and their whole organisation disturbed by being compounded of two distinct species, seems closely allied to that sterility which so frequently affects pure species, when their natural conditions of life have been disturbed. This view is supported by a parallelism of another kind;--namely, that the crossing of forms only slightly different is favourable to the vigour and fertility of their offspring; and that slight changes in the conditions of life are apparently favourable to the vigour and fertility of all organic beings. It is not surprising that the degree of difficulty in uniting two species, and the degree of sterility of their hybrid-offspring should generally correspond, though due to distinct causes; for both depend on the amount of difference of some kind between the species which are crossed. Nor is it surprising that the facility of effecting a first cross, the fertility of the hybrids produced from it, and the capacity of being grafted together--though this latter capacity evidently depends on widely different circumstances--should all run, to a certain extent, parallel with the systematic affinity of the forms which are subjected to experiment; for systematic affinity attempts to express all kinds of resemblance between all species. First crosses between forms known to be varieties, or sufficiently alike to be considered as varieties, and their mongrel offspring, are very generally, but not quite {278} universally, fertile. Nor is this nearly general and perfect fertility surprising, when we remember how liable we are to argue in a circle with respect to varieties in a state of nature; and when we remember that the greater number of varieties have been produced under domestication by the selection of mere external differences, and not of differences in the reproductive system. In all other respects, excluding fertility, there is a close general resemblance between hybrids and mongrels. Finally, then, the facts briefly given in this chapter do not seem to me opposed to, but even rather to support the view, that there is no fundamental distinction between species and varieties. * * * * * {279} CHAPTER IX. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD. On the absence of intermediate varieties at the present day--On the nature of extinct intermediate varieties; on their number--On the vast lapse of time, as inferred from the rate of deposition and of denudation--On the poorness of our palæontological collections--On the intermittence of geological formations--On the absence of intermediate varieties in any one formation--On the sudden appearance of groups of species--On their sudden appearance in the lowest known fossiliferous strata. In the sixth chapter I enumerated the chief objections which might be justly urged against the views maintained in this volume. Most of them have now been discussed. One, namely the distinctness of specific forms, and their not being blended together by innumerable transitional links, is a very obvious difficulty. I assigned reasons why such links do not commonly occur at the present day, under the circumstances apparently most favourable for their presence, namely on an extensive and continuous area with graduated physical conditions. I endeavoured to show, that the life of each species depends in a more important manner on the presence of other already defined organic forms, than on climate; and, therefore, that the really governing conditions of life do not graduate away quite insensibly like heat or moisture. I endeavoured, also, to show that intermediate varieties, from existing in lesser numbers than the forms which they connect, will generally be beaten out and exterminated during the course of further modification and improvement. The main cause, however, of innumerable intermediate links not now occurring everywhere throughout nature {280} depends on the very process of natural selection, through which new varieties continually take the places of and exterminate their parent-forms. But just in proportion as this process of extermination has acted on an enormous scale, so must the number of intermediate varieties, which have formerly existed on the earth, be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and gravest objection which can be urged against my theory. The explanation lies, as I believe, in the extreme imperfection of the geological record. In the first place it should always be borne in mind what sort of intermediate forms must, on my theory, have formerly existed. I have found it difficult, when looking at any two species, to avoid picturing to myself, forms _directly_ intermediate between them. But this is a wholly false view; we should always look for forms intermediate between each species and a common but unknown progenitor; and the progenitor will generally have differed in some respects from all its modified descendants. To give a simple illustration: the fantail and pouter pigeons have both descended from the rock-pigeon; if we possessed all the intermediate varieties which have ever existed, we should have an extremely close series between both and the rock-pigeon; but we should have no varieties directly intermediate between the fantail and pouter; none, for instance, combining a tail somewhat expanded with a crop somewhat enlarged, the characteristic features of these two breeds. These two breeds, moreover, have become so much modified, that if we had no historical or indirect evidence regarding their origin, it would not have been possible to have {281} determined from a mere comparison of their structure with that of the rock-pigeon, whether they had descended from this species or from some other allied species, such as C. oenas. So with natural species, if we look to forms very distinct, for instance to the horse and tapir, we have no reason to suppose that links ever existed directly intermediate between them, but between each and an unknown common parent. The common parent will have had in its whole organisation much general resemblance to the tapir and to the horse; but in some points of structure may have differed considerably from both, even perhaps more than they differ from each other. Hence in all such cases, we should be unable to recognise the parent-form of any two or more species, even if we closely compared the structure of the parent with that of its modified descendants, unless at the same time we had a nearly perfect chain of the intermediate links. It is just possible by my theory, that one of two living forms might have descended from the other; for instance, a horse from a tapir; and in this case _direct_ intermediate links will have existed between them. But such a case would imply that one form had remained for a very long period unaltered, whilst its descendants had undergone a vast amount of change; and the principle of competition between organism and organism, between child and parent, will render this a very rare event; for in all cases the new and improved forms of life tend to supplant the old and unimproved forms. By the theory of natural selection all living species have been connected with the parent-species of each genus, by differences not greater than we see between the varieties of the same species at the present {282} day; and these parent-species, now generally extinct, have in their turn been similarly connected with more ancient species; and so on backwards, always converging to the common ancestor of each great class. So that the number of intermediate and transitional links, between all living and extinct species, must have been inconceivably great. But assuredly, if this theory be true, such have lived upon this earth. _On the lapse of Time._--Independently of our not finding fossil remains of such infinitely numerous connecting links, it may be objected, that time will not have sufficed for so great an amount of organic change, all changes having been effected very slowly through natural selection. It is hardly possible for me even to recall to the reader, who may not be a practical geologist, the facts leading the mind feebly to comprehend the lapse of time. He who can read Sir Charles Lyell's grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, yet does not admit how incomprehensively vast have been the past periods of time, may at once close this volume. Not that it suffices to study the Principles of Geology, or to read special treatises by different observers on separate formations, and to mark how each author attempts to give an inadequate idea of the duration of each formation or even each stratum. A man must for years examine for himself great piles of superimposed strata, and watch the sea at work grinding down old rocks and making fresh sediment, before he can hope to comprehend anything of the lapse of time, the monuments of which we see around us. It is good to wander along lines of sea-coast, when formed of moderately hard rocks, and mark the {283} process of degradation. The tides in most cases reach the cliffs only for a short time twice a day, and the waves eat into them only when they are charged with sand or pebbles; for there is good evidence that pure water can effect little or nothing in wearing away rock. At last the base of the cliff is undermined, huge fragments fall down, and these remaining fixed, have to be worn away, atom by atom, until reduced in size they can be rolled about by the waves, and then are more quickly ground into pebbles, sand, or mud. But how often do we see along the bases of retreating cliffs rounded boulders, all thickly clothed by marine productions, showing how little they are abraded and how seldom they are rolled about! Moreover, if we follow for a few miles any line of rocky cliff, which is undergoing degradation, we find that it is only here and there, along a short length or round a promontory, that the cliffs are at the present time suffering. The appearance of the surface and the vegetation show that elsewhere years have elapsed since the waters washed their base. He who most closely studies the action of the sea on our shores, will, I believe, be most deeply impressed with the slowness with which rocky coasts are worn away. The observations on this head by Hugh Miller, and by that excellent observer Mr. Smith of Jordan Hill, are most impressive. With the mind thus impressed, let any one examine beds of conglomerate many thousand feet in thickness, which, though probably formed at a quicker rate than many other deposits, yet, from being formed of worn and rounded pebbles, each of which bears the stamp of time, are good to show how slowly the mass has been accumulated. In the Cordillera I estimated one pile of conglomerate at ten thousand feet in thickness. Let the {284} observer remember Lyell's profound remark that the thickness and extent of sedimentary formations are the result and measure of the degradation which the earth's crust has elsewhere suffered. And what an amount of degradation is implied by the sedimentary deposits of many countries! Professor Ramsay has given me the maximum thickness, in most cases from actual measurement, in a few cases from estimate, of each formation in different parts of Great Britain; and this is the result:-- Feet. Palæozoic strata (not including igneous beds) 57,154 Secondary strata 13,190 Tertiary strata 2,240 --making altogether 72,584 feet; that is, very nearly thirteen and three-quarters British miles. Some of the formations, which are represented in England by thin beds, are thousands of feet in thickness on the Continent. Moreover, between each successive formation, we have, in the opinion of most geologists, enormously long blank periods. So that the lofty pile of sedimentary rocks in Britain, gives but an inadequate idea of the time which has elapsed during their accumulation; yet what time this must have consumed! Good observers have estimated that sediment is deposited by the great Mississippi river at the rate of only 600 feet in a hundred thousand years. This estimate has no pretension to strict exactness; yet, considering over what wide spaces very fine sediment is transported by the currents of the sea, the process of accumulation in any one area must be extremely slow. But the amount of denudation which the strata have in many places suffered, independently of the rate of accumulation of the degraded matter, probably offers the best evidence of the lapse of time. I remember {285} having been much struck with the evidence of denudation, when viewing volcanic islands, which have been worn by the waves and pared all round into perpendicular cliffs of one or two thousand feet in height; for the gentle slope of the lava-streams, due to their formerly liquid state, showed at a glance how far the hard, rocky beds had once extended into the open ocean. The same story is still more plainly told by faults,--those great cracks along which the strata have been upheaved on one side, or thrown down on the other, to the height or depth of thousands of feet; for since the crust cracked, the surface of the land has been so completely planed down by the action of the sea, that no trace of these vast dislocations is externally visible. The Craven fault, for instance, extends for upwards of 30 miles, and along this line the vertical displacement of the strata has varied from 600 to 3000 feet. Prof. Ramsay has published an account of a downthrow in Anglesea of 2300 feet; and he informs me that he fully believes there is one in Merionethshire of 12,000 feet; yet in these cases there is nothing on the surface to show such prodigious movements; the pile of rocks on the one or other side having been smoothly swept away. The consideration of these facts impresses my mind almost in the same manner as does the vain endeavour to grapple with the idea of eternity. I am tempted to give one other case, the well-known one of the denudation of the Weald. Though it must be admitted that the denudation of the Weald has been a mere trifle, in comparison with that which has removed masses of our palæozoic strata, in parts ten thousand feet in thickness, as shown in Prof. Ramsay's masterly memoir on this subject: yet it is an admirable lesson to stand on the intermediate hilly country and look on the one hand at the North Downs, and {286} on the other hand at the South Downs; for, remembering that at no great distance to the west the northern and southern escarpments meet and close, one can safely picture to oneself the great dome of rocks which must have covered up the Weald within so limited a period as since the latter part of the Chalk formation. The distance from the northern to the southern Downs is about 22 miles, and the thickness of the several formations is on an average about 1100 feet, as I am informed by Prof. Ramsay. But if, as some geologists suppose, a range of older rocks underlies the Weald, on the flanks of which the overlying sedimentary deposits might have accumulated in thinner masses than elsewhere, the above estimate would be erroneous; but this source of doubt probably would not greatly affect the estimate as applied to the western extremity of the district. If, then, we knew the rate at which the sea commonly wears away a line of cliff of any given height, we could measure the time requisite to have denuded the Weald. This, of course cannot be done; but we may, in order to form some crude notion on the subject, assume that the sea would eat into cliffs 500 feet in height at the rate of one inch in a century. This will at first appear much too small an allowance; but it is the same as if we were to assume a cliff one yard in height to be eaten back along a whole line of coast at the rate of one yard in nearly every twenty-two years. I doubt whether any rock, even as soft as chalk, would yield at this rate excepting on the most exposed coasts; though no doubt the degradation of a lofty cliff would be more rapid from the breakage of the fallen fragments. On the other hand, I do not believe that any line of coast, ten or twenty miles in length, ever suffers degradation at the same time along its whole indented length; and we {287} must remember that almost all strata contain harder layers or nodules, which from long resisting attrition form a breakwater at the base. We may at least confidently believe that no rocky coast 500 feet in height commonly yields at the rate of a foot per century; for this would be the same in amount as a cliff one yard in height retreating twelve yards in twenty-two years; and no one, I think, who has carefully observed the shape of old fallen fragments at the base of cliffs, will admit any near approach to such rapid wearing away. Hence, under ordinary circumstances, I should infer that for a cliff 500 feet in height, a denudation of one inch per century for the whole length would be a sufficient allowance. At this rate, on the above data, the denudation of the Weald must have required 306,662,400 years; or say three hundred million years. But perhaps it would be safer to allow two or three inches per century, and this would reduce the number of years to one hundred and fifty or one hundred million years. The action of fresh water on the gently inclined Wealden district, when upraised, could hardly have been great, but it would somewhat reduce the above estimate. On the other hand, during oscillations of level, which we know this area has undergone, the surface may have existed for millions of years as land, and thus have escaped the action of the sea: when deeply submerged for perhaps equally long periods, it would, likewise, have escaped the action of the coast-waves. So that it is not improbable that a longer period than 300 million years has elapsed since the latter part of the Secondary period. I have made these few remarks because it is highly important for us to gain some notion, however imperfect, of the lapse of years. During each of these years, {288} over the whole world, the land and the water has been peopled by hosts of living forms. What an infinite number of generations, which the mind cannot grasp, must have succeeded each other in the long roll of years! Now turn to our richest geological museums, and what a paltry display we behold! _On the poorness of our Palæontological collections._--That our palæontological collections are very imperfect, is admitted by every one. The remark of that admirable palæontologist, the late Edward Forbes, should not be forgotten, namely, that numbers of our fossil species are known and named from single and often broken specimens, or from a few specimens collected on some one spot. Only a small portion of the surface of the earth has been geologically explored, and no part with sufficient care, as the important discoveries made every year in Europe prove. No organism wholly soft can be preserved. Shells and bones will decay and disappear when left on the bottom of the sea, where sediment is not accumulating. I believe we are continually taking a most erroneous view, when we tacitly admit to ourselves that sediment is being deposited over nearly the whole bed of the sea, at a rate sufficiently quick to embed and preserve fossil remains. Throughout an enormously large proportion of the ocean, the bright blue tint of the water bespeaks its purity. The many cases on record of a formation conformably covered, after an enormous interval of time, by another and later formation, without the underlying bed having suffered in the interval any wear and tear, seem explicable only on the view of the bottom of the sea not rarely lying for ages in an unaltered condition. The remains which do become embedded, if in sand or gravel, will when the beds are upraised generally be dissolved {289} by the percolation of rain-water. I suspect that but few of the very many animals which live on the beach between high and low watermark are preserved. For instance, the several species of the Chthamalinæ (a subfamily of sessile cirripedes) coat the rocks all over the world in infinite numbers: they are all strictly littoral, with the exception of a single Mediterranean species, which inhabits deep water and has been found fossil in Sicily, whereas not one other species has hitherto been found in any tertiary formation: yet it is now known that the genus Chthamalus existed during the chalk period. The molluscan genus Chiton offers a partially analogous case. With respect to the terrestrial productions which lived during the Secondary and Palæozoic periods, it is superfluous to state that our evidence from fossil remains is fragmentary in an extreme degree. For instance, not a land shell is known belonging to either of these vast periods, with the exception of one species discovered by Sir C. Lyell and Dr. Dawson in the carboniferous strata of North America, of which shell several specimens have now been collected. In regard to mammiferous remains, a single glance at the historical table published in the Supplement to Lyell's Manual, will bring home the truth, how accidental and rare is their preservation, far better than pages of detail. Nor is their rarity surprising, when we remember how large a proportion of the bones of tertiary mammals have been discovered either in caves or in lacustrine deposits; and that not a cave or true lacustrine bed is known belonging to the age of our secondary or palæozoic formations. But the imperfection in the geological record mainly results from another and more important cause than any of the foregoing; namely, from the several formations {290} being separated from each other by wide intervals of time. When we see the formations tabulated in written works, or when we follow them in nature, it is difficult to avoid believing that they are closely consecutive. But we know, for instance, from Sir R. Murchison's great work on Russia, what wide gaps there are in that country between the superimposed formations; so it is in North America, and in many other parts of the world. The most skilful geologist, if his attention had been exclusively confined to these large territories, would never have suspected that during the periods which were blank and barren in his own country, great piles of sediment, charged with new and peculiar forms of life, had elsewhere been accumulated. And if in each separate territory, hardly any idea can be formed of the length of time which has elapsed between the consecutive formations, we may infer that this could nowhere be ascertained. The frequent and great changes in the mineralogical composition of consecutive formations, generally implying great changes in the geography of the surrounding lands, whence the sediment has been derived, accords with the belief of vast intervals of time having elapsed between each formation. But we can, I think, see why the geological formations of each region are almost invariably intermittent; that is, have not followed each other in close sequence. Scarcely any fact struck me more when examining many hundred miles of the South American coasts, which have been upraised several hundred feet within the recent period, than the absence of any recent deposits sufficiently extensive to last for even a short geological period. Along the whole west coast, which is inhabited by a peculiar marine fauna, tertiary beds are so poorly developed, that no record of several {291} successive and peculiar marine faunas will probably be preserved to a distant age. A little reflection will explain why along the rising coast of the western side of South America, no extensive formations with recent or tertiary remains can anywhere be found, though the supply of sediment must for ages have been great, from the enormous degradation of the coast-rocks and from muddy streams entering the sea. The explanation, no doubt, is, that the littoral and sub-littoral deposits are continually worn away, as soon as they are brought up by the slow and gradual rising of the land within the grinding action of the coast-waves. We may, I think, safely conclude that sediment must be accumulated in extremely thick, solid, or extensive masses, in order to withstand the incessant action of the waves, when first upraised and during subsequent oscillations of level. Such thick and extensive accumulations of sediment may be formed in two ways; either, in profound depths of the sea, in which case, judging from the researches of E. Forbes, we may conclude that the bottom will be inhabited by extremely few animals, and the mass when upraised will give a most imperfect record of the forms of life which then existed; or, sediment may be accumulated to any thickness and extent over a shallow bottom, if it continue slowly to subside. In this latter case, as long as the rate of subsidence and supply of sediment nearly balance each other, the sea will remain shallow and favourable for life, and thus a fossiliferous formation thick enough, when upraised, to resist any amount of degradation, may be formed. I am convinced that all our ancient formations, which are rich in fossils, have thus been formed during subsidence. Since publishing my views on this subject in 1845, I have watched the progress of {292} Geology, and have been surprised to note how author after author, in treating of this or that great formation, has come to the conclusion that it was accumulated during subsidence. I may add, that the only ancient tertiary formation on the west coast of South America, which has been bulky enough to resist such degradation as it has as yet suffered, but which will hardly last to a distant geological age, was certainly deposited during a downward oscillation of level, and thus gained considerable thickness. All geological facts tell us plainly that each area has undergone numerous slow oscillations of level, and apparently these oscillations have affected wide spaces. Consequently formations rich in fossils and sufficiently thick and extensive to resist subsequent degradation, may have been formed over wide spaces during periods of subsidence, but only where the supply of sediment was sufficient to keep the sea shallow and to embed and preserve the remains before they had time to decay. On the other hand, as long as the bed of the sea remained stationary, _thick_ deposits could not have been accumulated in the shallow parts, which are the most favourable to life. Still less could this have happened during the alternate periods of elevation; or, to speak more accurately, the beds which were then accumulated will have been destroyed by being upraised and brought within the limits of the coast-action. Thus the geological record will almost necessarily be rendered intermittent. I feel much confidence in the truth of these views, for they are in strict accordance with the general principles inculcated by Sir C. Lyell; and E. Forbes subsequently but independently arrived at a similar conclusion. One remark is here worth a passing notice. During periods of elevation the area of the land and of the {293} adjoining shoal parts of the sea will be increased, and new stations will often be formed;--all circumstances most favourable, as previously explained, for the formation of new varieties and species; but during such periods there will generally be a blank in the geological record. On the other hand, during subsidence, the inhabited area and number of inhabitants will decrease (excepting the productions on the shores of a continent when first broken up into an archipelago), and consequently during subsidence, though there will be much extinction, fewer new varieties or species will be formed; and it is during these very periods of subsidence, that our great deposits rich in fossils have been accumulated. Nature may almost be said to have guarded against the frequent discovery of her transitional or linking forms. From the foregoing considerations it cannot be doubted that the geological record, viewed as a whole, is extremely imperfect; but if we confine our attention to any one formation, it becomes more difficult to understand, why we do not therein find closely graduated varieties between the allied species which lived at its commencement and at its close. Some cases are on record of the same species presenting distinct varieties in the upper and lower parts of the same formation, but, as they are rare, they may be here passed over. Although each formation has indisputably required a vast number of years for its deposition, I can see several reasons why each should not include a graduated series of links between the species which then lived; but I can by no means pretend to assign due proportional weight to the following considerations. Although each formation may mark a very long lapse of years, each perhaps is short compared with the period requisite to change one species into another. I am {294} aware that two palæontologists, whose opinions are worthy of much deference, namely Bronn and Woodward, have concluded that the average duration of each formation is twice or thrice as long as the average duration of specific forms. But insuperable difficulties, as it seems to me, prevent us coming to any just conclusion on this head. When we see a species first appearing in the middle of any formation, it would be rash in the extreme to infer that it had not elsewhere previously existed. So again when we find a species disappearing before the uppermost layers have been deposited, it would be equally rash to suppose that it then became wholly extinct. We forget how small the area of Europe is compared with the rest of the world; nor have the several stages of the same formation throughout Europe been correlated with perfect accuracy. With marine animals of all kinds, we may safely infer a large amount of migration during climatal and other changes; and when we see a species first appearing in any formation, the probability is that it only then first immigrated into that area. It is well known, for instance, that several species appeared somewhat earlier in the palæozoic beds of North America than in those of Europe; time having apparently been required for their migration from the American to the European seas. In examining the latest deposits of various quarters of the world, it has everywhere been noted, that some few still existing species are common in the deposit, but have become extinct in the immediately surrounding sea; or, conversely, that some are now abundant in the neighbouring sea, but are rare or absent in this particular deposit. It is an excellent lesson to reflect on the ascertained amount of migration of the inhabitants of Europe during the Glacial period, which forms only a part of one whole geological period; {295} and likewise to reflect on the great changes of level, on the inordinately great change of climate, on the prodigious lapse of time, all included within this same glacial period. Yet it may be doubted whether in any quarter of the world, sedimentary deposits, _including fossil remains_, have gone on accumulating within the same area during the whole of this period. It is not, for instance, probable that sediment was deposited during the whole of the glacial period near the mouth of the Mississippi, within that limit of depth at which marine animals can flourish; for we know what vast geographical changes occurred in other parts of America during this space of time. When such beds as were deposited in shallow water near the mouth of the Mississippi during some part of the glacial period shall have been upraised, organic remains will probably first appear and disappear at different levels, owing to the migration of species and to geographical changes. And in the distant future, a geologist examining these beds, might be tempted to conclude that the average duration of life of the embedded fossils had been less than that of the glacial period, instead of having been really far greater, that is extending from before the glacial epoch to the present day. In order to get a perfect gradation between two forms in the upper and lower parts of the same formation, the deposit must have gone on accumulating for a very long period, in order to have given sufficient time for the slow process of variation; hence the deposit will generally have to be a very thick one; and the species undergoing modification will have had to live on the same area throughout this whole time. But we have seen that a thick fossiliferous formation can only be accumulated during a period of subsidence; and to keep the depth approximately the same, which is necessary in {296} order to enable the same species to live on the same space, the supply of sediment must nearly have counterbalanced the amount of subsidence. But this same movement of subsidence will often tend to sink the area whence the sediment is derived, and thus diminish the supply whilst the downward movement continues. In fact, this nearly exact balancing between the supply of sediment and the amount of subsidence is probably a rare contingency; for it has been observed by more than one palæontologist, that very thick deposits are usually barren of organic remains, except near their upper or lower limits. It would seem that each separate formation, like the whole pile of formations in any country, has generally been intermittent in its accumulation. When we see, as is so often the case, a formation composed of beds of different mineralogical composition, we may reasonably suspect that the process of deposition has been much interrupted, as a change in the currents of the sea and a supply of sediment of a different nature will generally have been due to geographical changes requiring much time. Nor will the closest inspection of a formation give any idea of the time which its deposition has consumed. Many instances could be given of beds only a few feet in thickness, representing formations, elsewhere thousands of feet in thickness, and which must have required an enormous period for their accumulation; yet no one ignorant of this fact would have suspected the vast lapse of time represented by the thinner formation. Many cases could be given of the lower beds of a formation having been upraised, denuded, submerged, and then re-covered by the upper beds of the same formation,--facts, showing what wide, yet easily overlooked, intervals have occurred in its accumulation. In other cases we have the plainest evidence {297} in great fossilised trees, still standing upright as they grew, of many long intervals of time and changes of level during the process of deposition, which would never even have been suspected, had not the trees chanced to have been preserved: thus Messrs. Lyell and Dawson found carboniferous beds 1400 feet thick in Nova Scotia, with ancient root-bearing strata, one above the other, at no less than sixty-eight different levels. Hence, when the same species occur at the bottom, middle, and top of a formation, the probability is that they have not lived on the same spot during the whole period of deposition, but have disappeared and reappeared, perhaps many times, during the same geological period. So that if such species were to undergo a considerable amount of modification during any one geological period, a section would not probably include all the fine intermediate gradations which must on my theory have existed between them, but abrupt, though perhaps very slight, changes of form. It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; they grant some little variability to each species, but when they meet with a somewhat greater amount of difference between any two forms, they rank both as species, unless they are enabled to connect them together by close intermediate gradations. And this from the reasons just assigned we can seldom hope to effect in any one geological section. Supposing B and C to be two species, and a third, A, to be found in an underlying bed; even if A were strictly intermediate between B and C, it would simply be ranked as a third and distinct species, unless at the same time it could be most closely connected with either one or both forms by intermediate varieties. Nor should it be forgotten, as before explained, that A might be the actual progenitor {298} of B and C, and yet might not at all necessarily be strictly intermediate between them in all points of structure. So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of a formation, and unless we obtained numerous transitional gradations, we should not recognise their relationship, and should consequently be compelled to rank them all as distinct species. It is notorious on what excessively slight differences many palæontologists have founded their species; and they do this the more readily if the specimens come from different sub-stages of the same formation. Some experienced conchologists are now sinking many of the very fine species of D'Orbigny and others into the rank of varieties; and on this view we do find the kind of evidence of change which on my theory we ought to find. Moreover, if we look to rather wider intervals, namely, to distinct but consecutive stages of the same great formation, we find that the embedded fossils, though almost universally ranked as specifically different, yet are far more closely allied to each other than are the species found in more widely separated formations; but to this subject I shall have to return in the following chapter. One other consideration is worth notice: with animals and plants that can propagate rapidly and are not highly locomotive, there is reason to suspect, as we have formerly seen, that their varieties are generally at first local; and that such local varieties do not spread widely and supplant their parent-forms until they have been modified and perfected in some considerable degree. According to this view, the chance of discovering in a formation in any one country all the early stages of transition between any two forms, is small, for the successive changes are supposed to have been local or {299} confined to some one spot. Most marine animals have a wide range; and we have seen that with plants it is those which have the widest range, that oftenest present varieties; so that with shells and other marine animals, it is probably those which have had the widest range, far exceeding the limits of the known geological formations of Europe, which have oftenest given rise, first to local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any one geological formation. It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate varieties and thus proved to be the same species, until many specimens have been collected from many places; and in the case of fossil species this could rarely be effected by palæontologists. We shall, perhaps, best perceive the improbability of our being enabled to connect species by numerous, fine, intermediate, fossil links, by asking ourselves whether, for instance, geologists at some future period will be able to prove, that our different breeds of cattle, sheep, horses, and dogs have descended from a single stock or from several aboriginal stocks; or, again, whether certain sea-shells inhabiting the shores of North America, which are ranked by some conchologists as distinct species from their European representatives, and by other conchologists as only varieties, are really varieties or are, as it is called, specifically distinct. This could be effected only by the future geologist discovering in a fossil state numerous intermediate gradations; and such success seems to me improbable in the highest degree. Geological research, though it has added numerous species to existing and extinct genera, and has made the {300} intervals between some few groups less wide than they otherwise would have been, yet has done scarcely anything in breaking down the distinction between species, by connecting them together by numerous, fine, intermediate varieties; and this not having been effected, is probably the gravest and most obvious of all the many objections which may be urged against my views. Hence it will be worth while to sum up the foregoing remarks, under an imaginary illustration. The Malay Archipelago is of about the size of Europe from the North Cape to the Mediterranean, and from Britain to Russia; and therefore equals all the geological formations which have been examined with any accuracy, excepting those of the United States of America. I fully agree with Mr. Godwin-Austen, that the present condition of the Malay Archipelago, with its numerous large islands separated by wide and shallow seas, probably represents the former state of Europe, whilst most of our formations were accumulating. The Malay Archipelago is one of the richest regions of the whole world in organic beings; yet if all the species were to be collected which have ever lived there, how imperfectly would they represent the natural history of the world! But we have every reason to believe that the terrestrial productions of the archipelago would be preserved in an excessively imperfect manner in the formations which we suppose to be there accumulating. I suspect that not many of the strictly littoral animals, or of those which lived on naked submarine rocks, would be embedded; and those embedded in gravel or sand, would not endure to a distant epoch. Wherever sediment did not accumulate on the bed of the sea, or where it did not accumulate at a sufficient rate to protect organic bodies from decay, no remains could be preserved. I believe that fossiliferous formations could be formed {301} in the archipelago, of thickness sufficient to last to an age as distant in futurity as the secondary formations lie in the past, only during periods of subsidence. These periods of subsidence would be separated from each other by enormous intervals, during which the area would be either stationary or rising; whilst rising, each fossiliferous formation would be destroyed, almost as soon as accumulated, by the incessant coast-action, as we now see on the shores of South America. During the periods of subsidence there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be least perfect. It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would _exceed_ the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not fully preserved, transitional varieties would merely appear as so many distinct species. It is, also, probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatal changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would have to migrate, and no closely consecutive record of their modifications could be preserved in any one formation. Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy leads me to believe that it would be chiefly these far-ranging species which would oftenest produce new varieties; and the varieties would at first generally be local or confined to one place, but if possessed {302} of any decided advantage, or when further modified and improved, they would slowly spread and supplant their parent-forms. When such varieties returned to their ancient homes, as they would differ from their former state, in a nearly uniform, though perhaps extremely slight degree, they would, according to the principles followed by many palæontologists, be ranked as new and distinct species. If then, there be some degree of truth in these remarks, we have no right to expect to find in our geological formations, an infinite number of those fine transitional forms, which on my theory assuredly have connected all the past and present species of the same group into one long and branching chain of life. We ought only to look for a few links, some more closely, some more distantly related to each other; and these links, let them be ever so close, if found in different stages of the same formation, would, by most palæontologists, be ranked as distinct species. But I do not pretend that I should ever have suspected how poor a record of the mutations of life, the best preserved geological section presented, had not the difficulty of our not discovering innumerable transitional links between the species which appeared at the commencement and close of each formation, pressed so hardly on my theory. _On the sudden appearance of whole groups of Allied Species._--The abrupt manner in which whole groups of species suddenly appear in certain formations, has been urged by several palæontologists--for instance, by Agassiz, Pictet, and by none more forcibly than by Professor Sedgwick--as a fatal objection to the belief in the transmutation of species. If numerous species, belonging to the same genera or families, have really {303} started into life all at once, the fact would be fatal to the theory of descent with slow modification through natural selection. For the development of a group of forms, all of which have descended from some one progenitor, must have been an extremely slow process; and the progenitors must have lived long ages before their modified descendants. But we continually over-rate the perfection of the geological record, and falsely infer, because certain genera or families have not been found beneath a certain stage, that they did not exist before that stage. We continually forget how large the world is, compared with the area over which our geological formations have been carefully examined; we forget that groups of species may elsewhere have long existed and have slowly multiplied before they invaded the ancient archipelagoes of Europe and of the United States. We do not make due allowance for the enormous intervals of time, which have probably elapsed between our consecutive formations,--longer perhaps in most cases than the time required for the accumulation of each formation. These intervals will have given time for the multiplication of species from some one or some few parent-forms; and in the succeeding formation such species will appear as if suddenly created. I may here recall a remark formerly made, namely that it might require a long succession of ages to adapt an organism to some new and peculiar line of life, for instance to fly through the air; but that when this had been effected, and a few species had thus acquired a great advantage over other organisms, a comparatively short time would be necessary to produce many divergent forms, which would be able to spread rapidly and widely throughout the world. I will now give a few examples to illustrate these {304} remarks, and to show how liable we are to error in supposing that whole groups of species have suddenly been produced. I may recall the well-known fact that in geological treatises, published not many years ago, the great class of mammals was always spoken of as having abruptly come in at the commencement of the tertiary series. And now one of the richest known accumulations of fossil mammals, for its thickness, belongs to the middle of the secondary series; and one true mammal has been discovered in the new red sandstone at nearly the commencement of this great series. Cuvier used to urge that no monkey occurred in any tertiary stratum; but now extinct species have been discovered in India, South America, and in Europe even as far back as the eocene stage. Had it not been for the rare accident of the preservation of footsteps in the new red sandstone of the United States, who would have ventured to suppose that, besides reptiles, no less than at least thirty kinds of birds, some of gigantic size, existed during that period? Not a fragment of bone has been discovered in these beds. Notwithstanding that the number of joints shown in the fossil impressions correspond with the number in the several toes of living birds' feet, some authors doubt whether the animals which left the impressions were really birds. Until quite recently these authors might have maintained, and some have maintained, that the whole class of birds came suddenly into existence during an early tertiary period; but now we know, on the authority of Professor Owen (as may be seen in Lyell's 'Manual'), that a bird certainly lived during the deposition of the upper greensand. I may give another instance, which from having passed under my own eyes has much struck me. In a memoir on Fossil Sessile Cirripedes, I have stated that, from the {305} number of existing and extinct tertiary species; from the extraordinary abundance of the individuals of many species all over the world, from the Arctic regions to the equator, inhabiting various zones of depths from the upper tidal limits to 50 fathoms; from the perfect manner in which specimens are preserved in the oldest tertiary beds; from the ease with which even a fragment of a valve can be recognised; from all these circumstances, I inferred that had sessile cirripedes existed during the secondary periods, they would certainly have been preserved and discovered; and as not one species had then been discovered in beds of this age, I concluded that this great group had been suddenly developed at the commencement of the tertiary series. This was a sore trouble to me, adding as I thought one more instance of the abrupt appearance of a great group of species. But my work had hardly been published, when a skilful palæontologist, M. Bosquet, sent me a drawing of a perfect specimen of an unmistakeable sessile cirripede, which he had himself extracted from the chalk of Belgium. And, as if to make the case as striking as possible, this sessile cirripede was a Chthamalus, a very common, large, and ubiquitous genus, of which not one specimen has as yet been found even in any tertiary stratum. Hence we now positively know that sessile cirripedes existed during the secondary period; and these cirripedes might have been the progenitors of our many tertiary and existing species. The case most frequently insisted on by palæontologists of the apparently sudden appearance of a whole group of species, is that of the teleostean fishes, low down in the Chalk period. This group includes the large majority of existing species. Lately, Professor Pictet has carried their existence one sub-stage further back; and some palæontologists believe that certain {306} much older fishes, of which the affinities are as yet imperfectly known, are really teleostean. Assuming, however, that the whole of them did appear, as Agassiz believes, at the commencement of the chalk formation, the fact would certainly be highly remarkable; but I cannot see that it would be an insuperable difficulty on my theory, unless it could likewise be shown that the species of this group appeared suddenly and simultaneously throughout the world at this same period. It is almost superfluous to remark that hardly any fossil-fish are known from south of the equator; and by running through Pictet's Palæontology it will be seen that very few species are known from several formations in Europe. Some few families of fish now have a confined range; the teleostean fish might formerly have had a similarly confined range, and after having been largely developed in some one sea, might have spread widely. Nor have we any right to suppose that the seas of the world have always been so freely open from south to north as they are at present. Even at this day, if the Malay Archipelago were converted into land, the tropical parts of the Indian Ocean would form a large and perfectly enclosed basin, in which any great group of marine animals might be multiplied; and here they would remain confined, until some of the species became adapted to a cooler climate, and were enabled to double the southern capes of Africa or Australia, and thus reach other and distant seas. From these and similar considerations, but chiefly from our ignorance of the geology of other countries beyond the confines of Europe and the United States; and from the revolution in our palæontological ideas on many points, which the discoveries of even the last dozen years have effected, it seems to me to be about as rash in us to dogmatize on the succession of organic {307} beings throughout the world, as it would be for a naturalist to land for five minutes on some one barren point in Australia, and then to discuss the number and range of its productions. _On the sudden appearance of groups of Allied Species in the lowest known fossiliferous strata._--There is another and allied difficulty, which is much graver. I allude to the manner in which numbers of species of the same group, suddenly appear in the lowest known fossiliferous rocks. Most of the arguments which have convinced me that all the existing species of the same group have descended from one progenitor, apply with nearly equal force to the earliest known species. For instance, I cannot doubt that all the Silurian trilobites have descended from some one crustacean, which must have lived long before the Silurian age, and which probably differed greatly from any known animal. Some of the most ancient Silurian animals, as the Nautilus, Lingula, &c., do not differ much from living species; and it cannot on my theory be supposed, that these old species were the progenitors of all the species of the orders to which they belong, for they do not present characters in any degree intermediate between them. If, moreover, they had been the progenitors of these orders, they would almost certainly have been long ago supplanted and exterminated by their numerous and improved descendants. Consequently, if my theory be true, it is indisputable that before the lowest Silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the Silurian age to the present day; and that during these vast, yet quite unknown, periods of time, the world swarmed with living creatures. {308} To the question why we do not find records of these vast primordial periods, I can give no satisfactory answer. Several of the most eminent geologists, with Sir E. Murchison at their head, are convinced that we see in the organic remains of the lowest Silurian stratum the dawn of life on this planet. Other highly competent judges, as Lyell and the late E. Forbes, dispute this conclusion. We should not forget that only a small portion of the world is known with accuracy. M. Barrande has lately added another and lower stage to the Silurian system, abounding with new and peculiar species. Traces of life have been detected in the Longmynd beds, beneath Barrande's so-called primordial zone. The presence of phosphatic nodules and bituminous matter in some of the lowest azoic rocks, probably indicates the former existence of life at these periods. But the difficulty of understanding the absence of vast piles of fossiliferous strata, which on my theory no doubt were somewhere accumulated before the Silurian epoch, is very great. If these most ancient beds had been wholly worn away by denudation, or obliterated by metamorphic action, we ought to find only small remnants of the formations next succeeding them in age, and these ought to be very generally in a metamorphosed condition. But the descriptions which we now possess of the Silurian deposits over immense territories in Russia and in North America, do not support the view, that the older a formation is, the more it has always suffered the extremity of denudation and metamorphism. The case at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained. To show that it may hereafter receive some explanation, I will give the following hypothesis. From the nature of the organic remains which {309} do not appear to have inhabited profound depths, in the several formations of Europe and of the United States; and from the amount of sediment, miles in thickness, of which the formations are composed, we may infer that from first to last large islands or tracts of land, whence the sediment was derived, occurred in the neighbourhood of the existing continents of Europe and North America. But we do not know what was the state of things in the intervals between the successive formations; whether Europe and the United States during these intervals existed as dry land, or as a submarine surface near land, on which sediment was not deposited, or as the bed of an open and unfathomable sea. Looking to the existing oceans, which are thrice as extensive as the land, we see them studded with many islands; but not one oceanic island is as yet known to afford even a remnant of any palæozoic or secondary formation. Hence we may perhaps infer, that during the palæozoic and secondary periods, neither continents nor continental islands existed where our oceans now extend; for had they existed there, palæozoic and secondary formations would in all probability have been accumulated from sediment derived from their wear and tear; and would have been at least partially upheaved by the oscillations of level, which we may fairly conclude must have intervened during these enormously long periods. If then we may infer anything from these facts, we may infer that where our oceans now extend, oceans have extended from the remotest period of which we have any record; and on the other hand, that where continents now exist, large tracts of land have existed, subjected no doubt to great oscillations of level, since the earliest silurian period. The coloured map appended to my volume on Coral Reefs, led me to conclude that the great oceans are still mainly areas of {310} subsidence, the great archipelagoes still areas of oscillations of level, and the continents areas of elevation. But have we any right to assume that things have thus remained from the beginning of this world? Our continents seem to have been formed by a preponderance, during many oscillations of level, of the force of elevation; but may not the areas of preponderant movement have changed in the lapse of ages? At a period immeasurably antecedent to the silurian epoch, continents may have existed where oceans are now spread out; and clear and open oceans may have existed where our continents now stand. Nor should we be justified in assuming that if, for instance, the bed of the Pacific Ocean were now converted into a continent, we should there find formations older than the silurian strata, supposing such to have been formerly deposited; for it might well happen that strata which had subsided some miles nearer to the centre of the earth, and which had been pressed on by an enormous weight of superincumbent water, might have undergone far more metamorphic action than strata which have always remained nearer to the surface. The immense areas in some parts of the world, for instance in South America, of bare metamorphic rocks, which must have been heated under great pressure, have always seemed to me to require some special explanation; and we may perhaps believe that we see in these large areas, the many formations long anterior to the silurian epoch in a completely metamorphosed condition. The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner {311} in which whole groups of species appear in our European formations; the almost entire absence, as at present known, of fossiliferous formations beneath the Silurian strata, are all undoubtedly of the gravest nature. We see this in the plainest manner by the fact that all the most eminent palæontologists, namely Cuvier, Agassiz, Barrande, Falconer, E. Forbes, &c., and all our greatest geologists, as Lyell, Murchison, Sedgwick, &c., have unanimously, often vehemently, maintained the immutability of species. But I have reason to believe that one great authority, Sir Charles Lyell, from further reflexion entertains grave doubts on this subject. I feel how rash it is to differ from these authorities, to whom, with others, we owe all our knowledge. Those who think the natural geological record in any degree perfect, and who do not attach much weight to the facts and arguments of other kinds given in this volume, will undoubtedly at once reject my theory. For my part, following out Lyell's metaphor, I look at the natural geological record, as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines. Each word of the slowly-changing language, in which the history is supposed to be written, being more or less different in the interrupted succession of chapters, may represent the apparently abruptly changed forms of life, entombed in our consecutive, but widely separated, formations. On this view, the difficulties above discussed are greatly diminished, or even disappear. * * * * * {312} CHAPTER X. ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS. On the slow and successive appearance of new species--On their different rates of change--Species once lost do not reappear--Groups of species follow the same general rules in their appearance and disappearance as do single species--On Extinction--On simultaneous changes in the forms of life throughout the world--On the affinities of extinct species to each other and to living species--On the state of development of ancient forms--On the succession of the same types within the same areas--Summary of preceding and present chapters. Let us now see whether the several facts and rules relating to the geological succession of organic beings, better accord with the common view of the immutability of species, or with that of their slow and gradual modification, through descent and natural selection. New species have appeared very slowly, one after another, both on the land and in the waters. Lyell has shown that it is hardly possible to resist the evidence on this head in the case of the several tertiary stages; and every year tends to fill up the blanks between them, and to make the percentage system of lost and new forms more gradual. In some of the most recent beds, though undoubtedly of high antiquity if measured by years, only one or two species are lost forms, and only one or two are new forms, having here appeared for the first time, either locally, or, as far as we know, on the face of the earth. If we may trust the observations of Philippi in Sicily, the successive changes in the marine inhabitants of that island have been many and most gradual. The secondary formations are more broken; but, as Bronn has remarked, neither the appearance {313} nor disappearance of their many now extinct species has been simultaneous in each separate formation. Species of different genera and classes have not changed at the same rate, or in the same degree. In the oldest tertiary beds a few living shells may still be found in the midst of a multitude of extinct forms. Falconer has given a striking instance of a similar fact, in an existing crocodile associated with many strange and lost mammals and reptiles in the sub-Himalayan deposits. The Silurian Lingula differs but little from the living species of this genus; whereas most of the other Silurian Molluscs and all the Crustaceans have changed greatly. The productions of the land seem to change at a quicker rate than those of the sea, of which a striking instance has lately been observed in Switzerland. There is some reason to believe that organisms, considered high in the scale of nature, change more quickly than those that are low: though there are exceptions to this rule. The amount of organic change, as Pictet has remarked, does not strictly correspond with the succession of our geological formations; so that between each two consecutive formations, the forms of life have seldom changed in exactly the same degree. Yet if we compare any but the most closely related formations, all the species will be found to have undergone some change. When a species has once disappeared from the face of the earth, we have reason to believe that the same identical form never reappears. The strongest apparent exception to this latter rule, is that of the so-called "colonies" of M. Barrande, which intrude for a period in the midst of an older formation, and then allow the pre-existing fauna to reappear; but Lyell's explanation, namely, that it is a case of temporary migration from a distinct geographical province, seems to me satisfactory. {314} These several facts accord well with my theory. I believe in no fixed law of development, causing all the inhabitants of a country to change abruptly, or simultaneously, or to an equal degree. The process of modification must be extremely slow. The variability of each species is quite independent of that of all others. Whether such variability be taken advantage of by natural selection, and whether the variations be accumulated to a greater or lesser amount, thus causing a greater or lesser amount of modification in the varying species, depends on many complex contingencies,--on the variability being of a beneficial nature, on the power of intercrossing, on the rate of breeding, on the slowly changing physical conditions of the country, and more especially on the nature of the other inhabitants with which the varying species comes into competition. Hence it is by no means surprising that one species should retain the same identical form much longer than others; or, if changing, that it should change less. We see the same fact in geographical distribution; for instance, in the land-shells and coleopterous insects of Madeira having come to differ considerably from their nearest allies on the continent of Europe, whereas the marine shells and birds have remained unaltered. We can perhaps understand the apparently quicker rate of change in terrestrial and in more highly organised productions compared with marine and lower productions, by the more complex relations of the higher beings to their organic and inorganic conditions of life, as explained in a former chapter. When many of the inhabitants of a country have become modified and improved, we can understand, on the principle of competition, and on that of the many all-important relations of organism to organism, that any form which does not become in some degree modified and improved, {315} will be liable to be exterminated. Hence we can see why all the species in the same region do at last, if we look to wide enough intervals of time, become modified; for those which do not change will become extinct. In members of the same class the average amount of change, during long and equal periods of time, may, perhaps, be nearly the same; but as the accumulation of long-enduring fossiliferous formations depends on great masses of sediment having been deposited on areas whilst subsiding, our formations have been almost necessarily accumulated at wide and irregularly intermittent intervals; consequently the amount of organic change exhibited by the fossils embedded in consecutive formations is not equal. Each formation, on this view, does not mark a new and complete act of creation, but only an occasional scene, taken almost at hazard, in a slowly changing drama. We can clearly understand why a species when once lost should never reappear, even if the very same conditions of life, organic and inorganic, should recur. For though the offspring of one species might be adapted (and no doubt this has occurred in innumerable instances) to fill the exact place of another species in the economy of nature, and thus supplant it; yet the two forms--the old and the new--would not be identically the same; for both would almost certainly inherit different characters from their distinct progenitors. For instance, it is just possible, if our fantail-pigeons were all destroyed, that fanciers, by striving during long ages for the same object, might make a new breed hardly distinguishable from our present fantail; but if the parent rock-pigeon were also destroyed, and in nature we have every reason to believe that the parent-form will generally be supplanted and exterminated by its improved offspring, it is quite {316} incredible that a fantail, identical with the existing breed, could be raised from any other species of pigeon, or even from the other well-established races of the domestic pigeon, for the newly-formed fantail would be almost sure to inherit from its new progenitor some slight characteristic differences. Groups of species, that is, genera and families, follow the same general rules in their appearance and disappearance as do single species, changing more or less quickly, and in a greater or lesser degree. A group does not reappear after it has once disappeared; or its existence, as long as it lasts, is continuous. I am aware that there are some apparent exceptions to this rule, but the exceptions are surprisingly few, so few that E. Forbes, Pictet, and Woodward (though all strongly opposed to such views as I maintain) admit its truth; and the rule strictly accords with my theory. For as all the species of the same group have descended from some one species, it is clear that as long as any species of the group have appeared in the long succession of ages, so long must its members have continuously existed, in order to have generated either new and modified or the same old and unmodified forms. Species of the genus Lingula, for instance, must have continuously existed by an unbroken succession of generations, from the lowest Silurian stratum to the present day. We have seen in the last chapter that the species of a group sometimes falsely appear to have come in abruptly; and I have attempted to give an explanation of this fact, which if true would have been fatal to my views. But such cases are certainly exceptional; the general rule being a gradual increase in number, till the group reaches its maximum, and then, sooner or later, it gradually decreases. If the number of the species of a genus, or the number of {317} the genera of a family, be represented by a vertical line of varying thickness, crossing the successive geological formations in which the species are found, the line will sometimes falsely appear to begin at its lower end, not in a sharp point, but abruptly; it then gradually thickens upwards, sometimes keeping for a space of equal thickness, and ultimately thins out in the upper beds, marking the decrease and final extinction of the species. This gradual increase in number of the species of a group is strictly conformable with my theory; as the species of the same genus, and the genera of the same family, can increase only slowly and progressively; for the process of modification and the production of a number of allied forms must be slow and gradual,--one species giving rise first to two or three varieties, these being slowly converted into species, which in their turn produce by equally slow steps other species, and so on, like the branching of a great tree from a single stem, till the group becomes large. _On Extinction._--We have as yet spoken only incidentally of the disappearance of species and of groups of species. On the theory of natural selection the extinction of old forms and the production of new and improved forms are intimately connected together. The old notion of all the inhabitants of the earth having been swept away at successive periods by catastrophes, is very generally given up, even by those geologists, as Elie de Beaumont, Murchison, Barrande, &c., whose general views would naturally lead them to this conclusion. On the contrary, we have every reason to believe, from the study of the tertiary formations, that species and groups of species gradually disappear, one after another, first from one spot, then from another, and finally from the world. Both single species and whole {318} groups of species last for very unequal periods; some groups, as we have seen, having endured from the earliest known dawn of life to the present day; some having disappeared before the close of the palæozoic period. No fixed law seems to determine the length of time during which any single species or any single genus endures. There is reason to believe that the complete extinction of the species of a group is generally a slower process than their production: if the appearance and disappearance of a group of species be represented, as before, by a vertical line of varying thickness, the line is found to taper more gradually at its upper end, which marks the progress of extermination, than at its lower end, which marks the first appearance and increase in numbers of the species. In some cases, however, the extermination of whole groups of beings, as of ammonites towards the close of the secondary period, has been wonderfully sudden. The whole subject of the extinction of species has been involved in the most gratuitous mystery. Some authors have even supposed that as the individual has a definite length of life, so have species a definite duration. No one I think can have marvelled more at the extinction of species, than I have done. When I found in La Plata the tooth of a horse embedded with the remains of Mastodon, Megatherium, Toxodon, and other extinct monsters, which all co-existed with still living shells at a very late geological period, I was filled with astonishment; for seeing that the horse, since its introduction by the Spaniards into South America, has run wild over the whole country and has increased in numbers at an unparalleled rate, I asked myself what could so recently have exterminated the former horse under conditions of life apparently so favourable. But how utterly groundless was my astonishment! {319} Professor Owen soon perceived that the tooth, though so like that of the existing horse, belonged to an extinct species. Had this horse been still living, but in some degree rare, no naturalist would have felt the least surprise at its rarity; for rarity is the attribute of a vast number of species of all classes, in all countries. If we ask ourselves why this or that species is rare, we answer that something is unfavourable in its conditions of life; but what that something is, we can hardly ever tell. On the supposition of the fossil horse still existing as a rare species, we might have felt certain from the analogy of all other mammals, even of the slow-breeding elephant, and from the history of the naturalisation of the domestic horse in South America, that under more favourable conditions it would in a very few years have stocked the whole continent. But we could not have told what the unfavourable conditions were which checked its increase, whether some one or several contingencies, and at what period of the horse's life, and in what degree, they severally acted. If the conditions had gone on, however slowly, becoming less and less favourable, we assuredly should not have perceived the fact, yet the fossil horse would certainly have become rarer and rarer, and finally extinct;--its place being seized on by some more successful competitor. It is most difficult always to remember that the increase of every living being is constantly being checked by unperceived injurious agencies; and that these same unperceived agencies are amply sufficient to cause rarity, and finally extinction. We see in many cases in the more recent tertiary formations, that rarity precedes extinction; and we know that this has been the progress of events with those animals which have been exterminated, either locally or wholly, through {320} man's agency. I may repeat what I published in 1845, namely, that to admit that species generally become rare before they become extinct--to feel no surprise at the rarity of a species, and yet to marvel greatly when it ceases to exist, is much the same as to admit that sickness in the individual is the forerunner of death--to feel no surprise at sickness, but when the sick man dies, to wonder and to suspect that he died by some unknown deed of violence. The theory of natural selection is grounded on the belief that each new variety, and ultimately each new species, is produced and maintained by having some advantage over those with which it comes into competition; and the consequent extinction of less-favoured forms almost inevitably follows. It is the same with our domestic productions: when a new and slightly improved variety has been raised, it at first supplants the less improved varieties in the same neighbourhood; when much improved it is transported far and near, like our short-horn cattle, and takes the place of other breeds in other countries. Thus the appearance of new forms and the disappearance of old forms, both natural and artificial, are bound together. In certain flourishing groups, the number of new specific forms which have been produced within a given time is probably greater than that of the old specific forms which have been exterminated; but we know that the number of species has not gone on indefinitely increasing, at least during the later geological periods, so that looking to later times we may believe that the production of new forms has caused the extinction of about the same number of old forms. The competition will generally be most severe, as formerly explained and illustrated by examples, between the forms which are most like each other in all respects. {321} Hence the improved and modified descendants of a species will generally cause the extermination of the parent-species; and if many new forms have been developed from any one species, the nearest allies of that species, _i.e._ the species of the same genus, will be the most liable to extermination. Thus, as I believe, a number of new species descended from one species, that is a new genus, comes to supplant an old genus, belonging to the same family. But it must often have happened that a new species belonging to some one group will have seized on the place occupied by a species belonging to a distinct group, and thus caused its extermination; and if many allied forms be developed from the successful intruder, many will have to yield their places; and it will generally be allied forms, which will suffer from some inherited inferiority in common. But whether it be species belonging to the same or to a distinct class, which yield their places to other species which have been modified and improved, a few of the sufferers may often long be preserved, from being fitted to some peculiar line of life, or from inhabiting some distant and isolated station, where they have escaped severe competition. For instance, a single species of Trigonia, a great genus of shells in the secondary formations, survives in the Australian seas; and a few members of the great and almost extinct group of Ganoid fishes still inhabit our fresh waters. Therefore the utter extinction of a group is generally, as we have seen, a slower process than its production. With respect to the apparently sudden extermination of whole families or orders, as of Trilobites at the close of the palæozoic period and of Ammonites at the close of the secondary period, we must remember what has been already said on the probable wide intervals of time {322} between our consecutive formations; and in these intervals there may have been much slow extermination. Moreover, when by sudden immigration or by unusually rapid development, many species of a new group have taken possession of a new area, they will have exterminated in a correspondingly rapid manner many of the old inhabitants; and the forms which thus yield their places will commonly be allied, for they will partake of some inferiority in common. Thus, as it seems to me, the manner in which single species and whole groups of species become extinct, accords well with the theory of natural selection. We need not marvel at extinction; if we must marvel, let it be at our presumption in imagining for a moment that we understand the many complex contingencies, on which the existence of each species depends. If we forget for an instant, that each species tends to increase inordinately, and that some check is always in action, yet seldom perceived by us, the whole economy of nature will be utterly obscured. Whenever we can precisely say why this species is more abundant in individuals than that; why this species and not another can be naturalised in a given country; then, and not till then, we may justly feel surprise why we cannot account for the extinction of this particular species or group of species. _On the Forms of Life changing almost simultaneously throughout the World._--Scarcely any palæontological discovery is more striking than the fact, that the forms of life change almost simultaneously throughout the world. Thus our European Chalk formation can be recognised in many distant parts of the world, under the most different climates, where not a fragment of the mineral chalk itself can be found; namely, in North {323} America, in equatorial South America, in Tierra del Fuego, at the Cape of Good Hope, and in the peninsula of India. For at these distant points, the organic remains in certain beds present an unmistakeable degree of resemblance to those of the Chalk. It is not that the same species are met with; for in some cases not one species is identically the same, but they belong to the same families, genera, and sections of genera, and sometimes are similarly characterised in such trifling points as mere superficial sculpture. Moreover other forms, which are not found in the Chalk of Europe, but which occur in the formations either above or below, are similarly absent at these distant points of the world. In the several successive palæozoic formations of Russia, Western Europe and North America, a similar parallelism in the forms of life has been observed by several authors: so it is, according to Lyell, with the several European and North American tertiary deposits. Even if the few fossil species which are common to the Old and New Worlds be kept wholly out of view, the general parallelism in the successive forms of life, in the stages of the widely separated palæozoic and tertiary periods, would still be manifest, and the several formations could be easily correlated. These observations, however, relate to the marine inhabitants of distant parts of the world: we have not sufficient data to judge whether the productions of the land and of fresh water change at distant points in the same parallel manner. We may doubt whether they have thus changed: if the Megatherium, Mylodon, Macrauchenia, and Toxodon had been brought to Europe from La Plata, without any information in regard to their geological position, no one would have suspected that they had co-existed with still living sea-shells; but as these anomalous monsters co-existed with the {324} Mastodon and Horse, it might at least have been inferred that they had lived during one of the later tertiary stages. When the marine forms of life are spoken of as having changed simultaneously throughout the world, it must not be supposed that this expression relates to the same thousandth or hundred-thousandth year, or even that it has a very strict geological sense; for if all the marine animals which live at the present day in Europe, and all those that lived in Europe during the pleistocene period (an enormously remote period as measured by years, including the whole glacial epoch), were to be compared with those now living in South America or in Australia, the most skilful naturalist would hardly be able to say whether the existing or the pleistocene inhabitants of Europe resembled most closely those of the southern hemisphere. So, again, several highly competent observers believe that the existing productions of the United States are more closely related to those which lived in Europe during certain later tertiary stages, than to those which now live here; and if this be so, it is evident that fossiliferous beds deposited at the present day on the shores of North America would hereafter be liable to be classed with somewhat older European beds. Nevertheless, looking to a remotely future epoch, there can, I think, be little doubt that all the more modern _marine_ formations, namely, the upper pliocene, the pleistocene and strictly modern beds, of Europe, North and South America, and Australia, from containing fossil remains in some degree allied, and from not including those forms which are only found in the older underlying deposits, would be correctly ranked as simultaneous in a geological sense. The fact of the forms of life changing simultaneously, in the above large sense, at distant parts of the world, has greatly struck those admirable observers, MM. {325} de Verneuil and d'Archiac. After referring to the parallelism of the palæozoic forms of life in various parts of Europe, they add, "If struck by this strange sequence, we turn our attention to North America, and there discover a series of analogous phenomena, it will appear certain that all these modifications of species, their extinction, and the introduction of new ones, cannot be owing to mere changes in marine currents or other causes more or less local and temporary, but depend on general laws which govern the whole animal kingdom." M. Barrande has made forcible remarks to precisely the same effect. It is, indeed, quite futile to look to changes of currents, climate, or other physical conditions, as the cause of these great mutations in the forms of life throughout the world, under the most different climates. We must, as Barrande has remarked, look to some special law. We shall see this more clearly when we treat of the present distribution of organic beings, and find how slight is the relation between the physical conditions of various countries, and the nature of their inhabitants. This great fact of the parallel succession of the forms of life throughout the world, is explicable on the theory of natural selection. New species are formed by new varieties arising, which have some advantage over older forms; and those forms, which are already dominant, or have some advantage over the other forms in their own country, would naturally oftenest give rise to new varieties or incipient species; for these latter must be victorious in a still higher degree in order to be preserved and to survive. We have distinct evidence on this head, in the plants which are dominant, that is, which are commonest in their own homes, and are most widely diffused, having produced the greatest number of new varieties. It is also natural that the {326} dominant, varying, and far-spreading species, which already have invaded to a certain extent the territories of other species, should be those which would have the best chance of spreading still further, and of giving rise in new countries to new varieties and species. The process of diffusion may often be very slow, being dependent on climatal and geographical changes, or on strange accidents, but in the long run the dominant forms will generally succeed in spreading. The diffusion would, it is probable, be slower with the terrestrial inhabitants of distinct continents than with the marine inhabitants of the continuous sea. We might therefore expect to find, as we apparently do find, a less strict degree of parallel succession in the productions of the land than of the sea. Dominant species spreading from any region might encounter still more dominant species, and then their triumphant course, or even their existence, would cease. We know not at all precisely what are all the conditions most favourable for the multiplication of new and dominant species; but we can, I think, clearly see that a number of individuals, from giving a better chance of the appearance of favourable variations, and that severe competition with many already existing forms, would be highly favourable, as would be the power of spreading into new territories. A certain amount of isolation, recurring at long intervals of time, would probably be also favourable, as before explained. One quarter of the world may have been most favourable for the production of new and dominant species on the land, and another for those in the waters of the sea. If two great regions had been for a long period favourably circumstanced in an equal degree, whenever their inhabitants met, the battle would be prolonged and severe; and some from one birthplace and some from the other might be victorious. But in the course of time, the {327} forms dominant in the highest degree, wherever produced, would tend everywhere to prevail. As they prevailed, they would cause the extinction of other and inferior forms; and as these inferior forms would be allied in groups by inheritance, whole groups would tend slowly to disappear; though here and there a single member might long be enabled to survive. Thus, as it seems to me, the parallel, and, taken in a large sense, simultaneous, succession of the same forms of life throughout the world, accords well with the principle of new species having been formed by dominant species spreading widely and varying; the new species thus produced being themselves dominant owing to inheritance, and to having already had some advantage over their parents or over other species; these again spreading, varying, and producing new species. The forms which are beaten and which yield their places to the new and victorious forms, will generally be allied in groups, from inheriting some inferiority in common; and therefore as new and improved groups spread throughout the world, old groups will disappear from the world; and the succession of forms in both ways will everywhere tend to correspond. There is one other remark connected with this subject worth making. I have given my reasons for believing that all our greater fossiliferous formations were deposited during periods of subsidence; and that blank intervals of vast duration occurred during the periods when the bed of the sea was either stationary or rising, and likewise when sediment was not thrown down quickly enough to embed and preserve organic remains. During these long and blank intervals I suppose that the inhabitants of each region underwent a considerable amount of modification and extinction, and that there was much migration from {328} other parts of the world. As we have reason to believe that large areas are affected by the same movement, it is probable that strictly contemporaneous formations have often been accumulated over very wide spaces in the same quarter of the world; but we are far from having any right to conclude that this has invariably been the case, and that large areas have invariably been affected by the same movements. When two formations have been deposited in two regions during nearly, but not exactly the same period, we should find in both, from the causes explained in the foregoing paragraphs, the same general succession in the forms of life; but the species would not exactly correspond; for there will have been a little more time in the one region than in the other for modification, extinction, and immigration. I suspect that cases of this nature occur in Europe. Mr. Prestwich, in his admirable Memoirs on the eocene deposits of England and France, is able to draw a close general parallelism between the successive stages in the two countries; but when he compares certain stages in England with those in France, although he finds in both a curious accordance in the numbers of the species belonging to the same genera, yet the species themselves differ in a manner very difficult to account for, considering the proximity of the two areas,--unless, indeed, it be assumed that an isthmus separated two seas inhabited by distinct, but contemporaneous, faunas. Lyell has made similar observations on some of the later tertiary formations. Barrande, also, shows that there is a striking general parallelism in the successive Silurian deposits of Bohemia and Scandinavia; nevertheless he finds a surprising amount of difference in the species. If the several formations in these regions have not been deposited during the same exact {329} periods,--a formation in one region often corresponding with a blank interval in the other,--and if in both regions the species have gone on slowly changing during the accumulation of the several formations and during the long intervals of time between them; in this case, the several formations in the two regions could be arranged in the same order, in accordance with the general succession of the form of life, and the order would falsely appear to be strictly parallel; nevertheless the species would not all be the same in the apparently corresponding stages in the two regions. _On the Affinities of extinct Species to each other, and to living forms._--Let us now look to the mutual affinities of extinct and living species. They all fall into one grand natural system; and this fact is at once explained on the principle of descent. The more ancient any form is, the more, as a general rule, it differs from living forms. But, as Buckland long ago remarked, all fossils can be classed either in still existing groups, or between them. That the extinct forms of life help to fill up the wide intervals between existing genera, families, and orders, cannot be disputed. For if we confine our attention either to the living or to the extinct alone, the series is far less perfect than if we combine both into one general system. With respect to the Vertebrata, whole pages could be filled with striking illustrations from our great palaeontologist, Owen, showing how extinct animals fall in between existing groups. Cuvier ranked the Ruminants and Pachyderms, as the two most distinct orders of mammals; but Owen has discovered so many fossil links, that he has had to alter the whole classification of these two orders; and has placed certain pachyderms in the same sub-order with ruminants: for example, he dissolves by fine gradations the apparently {330} wide difference between the pig and the camel. In regard to the Invertebrata, Barrande, and a higher authority could not be named, asserts that he is every day taught that Palaeozoic animals, though belonging to the same orders, families, or genera with those living at the present day, were not at this early epoch limited in such distinct groups as they now are. Some writers have objected to any extinct species or group of species being considered as intermediate between living species or groups. If by this term it is meant that an extinct form is directly intermediate in all its characters between two living forms, the objection is probably valid. But I apprehend that in a perfectly natural classification many fossil species would have to stand between living species, and some extinct genera between living genera, even between genera belonging to distinct families. The most common case, especially with respect to very distinct groups, such as fish and reptiles, seems to be, that supposing them to be distinguished at the present day from each other by a dozen characters, the ancient members of the same two groups would be distinguished by a somewhat lesser number of characters, so that the two groups, though formerly quite distinct, at that period made some small approach to each other. It is a common belief that the more ancient a form is, by so much the more it tends to connect by some of its characters groups now widely separated from each other. This remark no doubt must be restricted to those groups which have undergone much change in the course of geological ages; and it would be difficult to prove the truth of the proposition, for every now and then even a living animal, as the Lepidosiren, is discovered having affinities directed towards very distinct groups. Yet if we compare the older Reptiles and {331} Batrachians, the older Fish, the older Cephalopods, and the eocene Mammals, with the more recent members of the same classes, we must admit that there is some truth in the remark. Let us see how far these several facts and inferences accord with the theory of descent with modification. As the subject is somewhat complex, I must request the reader to turn to the diagram in the fourth chapter. We may suppose that the numbered letters represent genera, and the dotted lines diverging from them the species in each genus. The diagram is much too simple, too few genera and too few species being given, but this is unimportant for us. The horizontal lines may represent successive geological formations, and all the forms beneath the uppermost line may be considered as extinct. The three existing genera, a^{14}, q^{14}, p^{14}, will form a small family; b^{14} and f^{14} a closely allied family or sub-family; and o^{14}, e^{14}, m^{14}, a third family. These three families, together with the many extinct genera on the several lines of descent diverging from the parent-form (A), will form an order; for all will have inherited something in common from their ancient and common progenitor. On the principle of the continued tendency to divergence of character, which was formerly illustrated by this diagram, the more recent any form is, the more it will generally differ from its ancient progenitor. Hence we can understand the rule that the most ancient fossils differ most from existing forms. We must not, however, assume that divergence of character is a necessary contingency; it depends solely on the descendants from a species being thus enabled to seize on many and different places in the economy of nature. Therefore it is quite possible, as we have seen in the case of some Silurian forms, that a species might go on being slightly modified in relation to its slightly altered conditions of {332} life, and yet retain throughout a vast period the same general characteristics. This is represented in the diagram by the letter F^{14}. All the many forms, extinct and recent, descended from (A), make, as before remarked, one order; and this order, from the continued effects of extinction and divergence of character, has become divided into several sub-families and families, some of which are supposed to have perished at different periods, and some to have endured to the present day. By looking at the diagram we can see that if many of the extinct forms, supposed to be embedded in the successive formations, were discovered at several points low down in the series, the three existing families on the uppermost line would be rendered less distinct from each other. If, for instance, the genera a^1, a^5, a^{10}, f^8, m^3, m^6, m^9, were disinterred, these three families would be so closely linked together that they probably would have to be united into one great family, in nearly the same manner as has occurred with ruminants and pachyderms. Yet he who objected to call the extinct genera, which thus linked the living genera of three families together, intermediate in character, would be justified, as they are intermediate, not directly, but only by a long and circuitous course through many widely different forms. If many extinct forms were to be discovered above one of the middle horizontal lines or geological formations --for instance, above No. VI.--but none from beneath this line, then only the two families on the left hand (namely, a^{14}, &c., and b^{14}, &c.) would have to be united into one family; and the two other families (namely, a^{14} to f^{14} now including five genera, and o^{14} to m^{14}) would yet remain distinct. These two families, however, would be less distinct from each other than they were before the discovery of the fossils. If, for instance, we suppose the existing genera of the two families to differ from each {333} other by a dozen characters, in this case the genera, at the early period marked VI., would differ by a lesser number of characters; for at this early stage of descent they have not diverged in character from the common progenitor of the order, nearly so much as they subsequently diverged. Thus it comes that ancient and extinct genera are often in some slight degree intermediate in character between their modified descendants, or between their collateral relations. In nature the case will be far more complicated than is represented in the diagram; for the groups will have been more numerous, they will have endured for extremely unequal lengths of time, and will have been modified in various degrees. As we possess only the last volume of the geological record, and that in a very broken condition, we have no right to expect, except in very rare cases, to fill up wide intervals in the natural system, and thus unite distinct families or orders. All that we have a right to expect, is that those groups, which have within known geological periods undergone much modification, should in the older formations make some slight approach to each other; so that the older members should differ less from each other in some of their characters than do the existing members of the same groups; and this by the concurrent evidence of our best palæontologists seems frequently to be the case. Thus, on the theory of descent with modification, the main facts with respect to the mutual affinities of the extinct forms of life to each other and to living forms, seem to me explained in a satisfactory manner. And they are wholly inexplicable on any other view. On this same theory, it is evident that the fauna of any great period in the earth's history will be intermediate in general character between that which preceded and that which succeeded it. Thus, the species which lived at the sixth great stage of descent in the {334} diagram are the modified offspring of those which lived at the fifth stage, and are the parents of those which became still more modified at the seventh stage; hence they could hardly fail to be nearly intermediate in character between the forms of life above and below. We must, however, allow for the entire extinction of some preceding forms, and in any one region for the immigration of new forms from other regions, and for a large amount of modification, during the long and blank intervals between the successive formations. Subject to these allowances, the fauna of each geological period undoubtedly is intermediate in character, between the preceding and succeeding faunas. I need give only one instance, namely, the manner in which the fossils of the Devonian system, when this system was first discovered, were at once recognised by palæontologists as intermediate in character between those of the overlying carboniferous, and underlying Silurian system. But each fauna is not necessarily exactly intermediate, as unequal intervals of time have elapsed between consecutive formations. It is no real objection to the truth of the statement, that the fauna of each period as a whole is nearly intermediate in character between the preceding and succeeding faunas, that certain genera offer exceptions to the rule. For instance, mastodons and elephants, when arranged by Dr. Falconer in two series, first according to their mutual affinities and then according to their periods of existence, do not accord in arrangement. The species extreme in character are not the oldest, or the most recent; nor are those which are intermediate in character, intermediate in age. But supposing for an instant, in this and other such cases, that the record of the first appearance and disappearance of the species was perfect, we have no reason to believe that forms successively produced necessarily endure for {335} corresponding lengths of time: a very ancient form might occasionally last much longer than a form elsewhere subsequently produced, especially in the case of terrestrial productions inhabiting separated districts. To compare small things with great: if the principal living and extinct races of the domestic pigeon were arranged as well as they could be in serial affinity, this arrangement would not closely accord with the order in time of their production, and still less with the order of their disappearance; for the parent rock-pigeon now lives; and many varieties between the rock-pigeon and the carrier have become extinct; and carriers which are extreme in the important character of length of beak originated earlier than short-beaked tumblers, which are at the opposite end of the series in this same respect. Closely connected with the statement, that the organic remains from an intermediate formation are in some degree intermediate in character, is the fact, insisted on by all palæontologists, that fossils from two consecutive formations are far more closely related to each other, than are the fossils from two remote formations. Pictet gives as a well-known instance, the general resemblance of the organic remains from the several stages of the Chalk formation, though the species are distinct in each stage. This fact alone, from its generality, seems to have shaken Professor Pictet in his firm belief in the immutability of species. He who is acquainted with the distribution of existing species over the globe, will not attempt to account for the close resemblance of the distinct species in closely consecutive formations, by the physical conditions of the ancient areas having remained nearly the same. Let it be remembered that the forms of life, at least those inhabiting the sea, have changed almost simultaneously throughout the world, and therefore under the most different climates and conditions. Consider the {336} prodigious vicissitudes of climate during the pleistocene period, which includes the whole glacial period, and note how little the specific forms of the inhabitants of the sea have been affected. On the theory of descent, the full meaning of the fact of fossil remains from closely consecutive formations, though ranked as distinct species, being closely related, is obvious. As the accumulation of each formation has often been interrupted, and as long blank intervals have intervened between successive formations, we ought not to expect to find, as I attempted to show in the last chapter, in any one or two formations all the intermediate varieties between the species which appeared at the commencement and close of these periods; but we ought to find after intervals, very long as measured by years, but only moderately long as measured geologically, closely allied forms, or, as they have been called by some authors, representative species; and these we assuredly do find. We find, in short, such evidence of the slow and scarcely sensible mutation of specific forms, as we have a just right to expect to find. _On the state of Development of Ancient Forms._--There has been much discussion whether recent forms are more highly developed than ancient. I will not here enter on this subject, for naturalists have not as yet defined to each other's satisfaction what is meant by high and low forms. The best definition probably is, that the higher forms have their organs more distinctly specialised for different functions; and as such division of physiological labour seems to be an advantage to each being, natural selection will constantly tend in so far to make the later and more modified forms higher than their early progenitors, or than the slightly modified descendants of such progenitors. In a more general sense the {337} more recent forms must, on my theory, be higher than the more ancient; for each new species is formed by having had some advantage in the struggle for life over other and preceding forms. If under a nearly similar climate, the eocene inhabitants of one quarter of the world were put into competition with the existing inhabitants of the same or some other quarter, the eocene fauna or flora would certainly be beaten and exterminated; as would a secondary fauna by an eocene, and a palæozoic fauna by a secondary fauna. I do not doubt that this process of improvement has affected in a marked and sensible manner the organisation of the more recent and victorious forms of life, in comparison with the ancient and beaten forms; but I can see no way of testing this sort of progress. Crustaceans, for instance, not the highest in their own class, may have beaten the highest molluscs. From the extraordinary manner in which European productions have recently spread over New Zealand, and have seized on places which must have been previously occupied, we may believe, if all the animals and plants of Great Britain were set free in New Zealand, that in the course of time a multitude of British forms would become thoroughly naturalized there, and would exterminate many of the natives. On the other hand, from what we see now occurring in New Zealand, and from hardly a single inhabitant of the southern hemisphere having become wild in any part of Europe, we may doubt, if all the productions of New Zealand were set free in Great Britain, whether any considerable number would be enabled to seize on places now occupied by our native plants and animals. Under this point of view, the productions of Great Britain may be said to be higher than those of New Zealand. Yet the most skilful naturalist from an examination of the {338} species of the two countries could not have foreseen this result. Agassiz insists that ancient animals resemble to a certain extent the embryos of recent animals of the same classes; or that the geological succession of extinct forms is in some degree parallel to the embryological development of recent forms. I must follow Pictet and Huxley in thinking that the truth of this doctrine is very far from proved. Yet I fully expect to see it hereafter confirmed, at least in regard to subordinate groups, which have branched off from each other within comparatively recent times. For this doctrine of Agassiz accords well with the theory of natural selection. In a future chapter I shall attempt to show that the adult differs from its embryo, owing to variations supervening at a not early age, and being inherited at a corresponding age. This process, whilst it leaves the embryo almost unaltered, continually adds, in the course of successive generations, more and more difference to the adult. Thus the embryo comes to be left as a sort of picture, preserved by nature, of the ancient and less modified condition of each animal. This view may be true, and yet it may never be capable of full proof. Seeing, for instance, that the oldest known mammals, reptiles, and fish strictly belong to their own proper classes, though some of these old forms are in a slight degree less distinct from each other than are the typical members of the same groups at the present day, it would be vain to look for animals having the common embryological character of the Vertebrata, until beds far beneath the lowest Silurian strata are discovered--a discovery of which the chance is very small. _On the Succession of the same Types within the same {339} areas, during the later tertiary periods._--Mr. Clift many years ago showed that the fossil mammals from the Australian caves were closely allied to the living marsupials of that continent. In South America, a similar relationship is manifest, even to an uneducated eye, in the gigantic pieces of armour like those of the armadillo, found in several parts of La Plata; and Professor Owen has shown in the most striking manner that most of the fossil mammals, buried there in such numbers, are related to South American types. This relationship is even more clearly seen in the wonderful collection of fossil bones made by MM. Lund and Clausen in the caves of Brazil. I was so much impressed with these facts that I strongly insisted, in 1839 and 1845, on this "law of the succession of types,"--on "this wonderful relationship in the same continent between the dead and the living." Professor Owen has subsequently extended the same generalisation to the mammals of the Old World. We see the same law in this author's restorations of the extinct and gigantic birds of New Zealand. We see it also in the birds of the caves of Brazil. Mr. Woodward has shown that the same law holds good with sea-shells, but from the wide distribution of most genera of molluscs, it is not well displayed by them. Other cases could be added, as the relation between the extinct and living land-shells of Madeira; and between the extinct and living brackish-water shells of the Aralo-Caspian Sea. Now what does this remarkable law of the succession of the same types within the same areas mean? He would be a bold man, who after comparing the present climate of Australia and of parts of South America under the same latitude, would attempt to account, on the one hand, by dissimilar physical conditions for the dissimilarity of the inhabitants of these two continents, {340} and, on the other hand, by similarity of conditions, for the uniformity of the same types in each during the later tertiary periods. Nor can it be pretended that it is an immutable law that marsupials should have been chiefly or solely produced in Australia; or that Edentata and other American types should have been solely produced in South America. For we know that Europe in ancient times was peopled by numerous marsupials; and I have shown in the publications above alluded to, that in America the law of distribution of terrestrial mammals was formerly different from what it now is. North America formerly partook strongly of the present character of the southern half of the continent; and the southern half was formerly more closely allied, than it is at present, to the northern half. In a similar manner we know from Falconer and Cautley's discoveries, that northern India was formerly more closely related in its mammals to Africa than it is at the present time. Analogous facts could be given in relation to the distribution of marine animals. On the theory of descent with modification, the great law of the long enduring, but not immutable, succession of the same types within the same areas, is at once explained; for the inhabitants of each quarter of the world will obviously tend to leave in that quarter, during the next succeeding period of time, closely allied though in some degree modified descendants. If the inhabitants of one continent formerly differed greatly from those of another continent, so will their modified descendants still differ in nearly the same manner and degree. But after very long intervals of time and after great geographical changes, permitting much inter-migration, the feebler will yield to the more dominant forms, and there will be nothing immutable in the laws of past and present distribution. {341} It may be asked in ridicule, whether I suppose that the megatherium and other allied huge monsters have left behind them in South America, the sloth, armadillo, and anteater, as their degenerate descendants. This cannot for an instant be admitted. These huge animals have become wholly extinct, and have left no progeny. But in the caves of Brazil, there are many extinct species which are closely allied in size and in other characters to the species still living in South America; and some of these fossils may be the actual progenitors of living species. It must not be forgotten that, on my theory, all the species of the same genus have descended from some one species; so that if six genera, each having eight species, be found in one geological formation, and in the next succeeding formation there be six other allied or representative genera with the same number of species, then we may conclude that only one species of each of the six older genera has left modified descendants, constituting the six new genera. The other seven species of the old genera have all died out and have left no progeny. Or, which would probably be a far commoner case, two or three species of two or three alone of the six older genera will have been the parents of the six new genera; the other old species and the other whole old genera having become utterly extinct. In failing orders, with the genera and species decreasing in numbers, as apparently is the case of the Edentata of South America, still fewer genera and species will have left modified blood-descendants. _Summary of the preceding and present Chapters._--I have attempted to show that the geological record is extremely imperfect; that only a small portion of the globe has been geologically explored with care; that {342} only certain classes of organic beings have been largely preserved in a fossil state; that the number both of specimens and of species, preserved in our museums, is absolutely as nothing compared with the incalculable number of generations which must have passed away even during a single formation; that, owing to subsidence being necessary for the accumulation of fossiliferous deposits thick enough to resist future degradation, enormous intervals of time have elapsed between the successive formations; that there has probably been more extinction during the periods of subsidence, and more variation during the periods of elevation, and during the latter the record will have been least perfectly kept; that each single formation has not been continuously deposited; that the duration of each formation is, perhaps, short compared with the average duration of specific forms; that migration has played an important part in the first appearance of new forms in any one area and formation; that widely ranging species are those which have varied most, and have oftenest given rise to new species; and that varieties have at first often been local. All these causes taken conjointly, must have tended to make the geological record extremely imperfect, and will to a large extent explain why we do not find interminable varieties, connecting together all the extinct and existing forms of life by the finest graduated steps. He who rejects these views on the nature of the geological record, will rightly reject my whole theory. For he may ask in vain where are the numberless transitional links which must formerly have connected the closely allied or representative species, found in the several stages of the same great formation. He may disbelieve in the enormous intervals of time which have elapsed between our consecutive formations; he {343} may overlook how important a part migration must have played, when the formations of any one great region alone, as that of Europe, are considered; he may urge the apparent, but often falsely apparent, sudden coming in of whole groups of species. He may ask where are the remains of those infinitely numerous organisms which must have existed long before the first bed of the Silurian system was deposited: I can answer this latter question only hypothetically, by saying that as far as we can see, where our oceans now extend they have for an enormous period extended, and where our oscillating continents now stand they have stood ever since the Silurian epoch; but that long before that period, the world may have presented a wholly different aspect; and that the older continents, formed of formations older than any known to us, may now all be in a metamorphosed condition, or may lie buried under the ocean. Passing from these difficulties, all the other great leading facts in palæontology seem to me simply to follow on the theory of descent with modification through natural selection. We can thus understand how it is that new species come in slowly and successively; how species of different classes do not necessarily change together, or at the same rate, or in the same degree; yet in the long run that all undergo modification to some extent. The extinction of old forms is the almost inevitable consequence of the production of new forms. We can understand why when a species has once disappeared it never reappears. Groups of species increase in numbers slowly, and endure for unequal periods of time; for the process of modification is necessarily slow, and depends on many complex contingencies. The dominant species of the larger dominant groups tend to leave many modified {344} descendants, and thus new sub-groups and groups are formed. As these are formed, the species of the less vigorous groups, from their inferiority inherited from a common progenitor, tend to become extinct together, and to leave no modified offspring on the face of the earth. But the utter extinction of a whole group of species may often be a very slow process, from the survival of a few descendants, lingering in protected and isolated situations. When a group has once wholly disappeared, it does not reappear; for the link of generation has been broken. We can understand how the spreading of the dominant forms of life, which are those that oftenest vary, will in the long run tend to people the world with allied, but modified, descendants; and these will generally succeed in taking the places of those groups of species which are their inferiors in the struggle for existence. Hence, after long intervals of time, the productions of the world will appear to have changed simultaneously. We can understand how it is that all the forms of life, ancient and recent, make together one grand system; for all are connected by generation. We can understand, from the continued tendency to divergence of character, why the more ancient a form is, the more it generally differs from those now living. Why ancient and extinct forms often tend to fill up gaps between existing forms, sometimes blending two groups previously classed as distinct into one; but more commonly only bringing them a little closer together. The more ancient a form is, the more often, apparently, it displays characters in some degree intermediate between groups now distinct; for the more ancient a form is, the more nearly it will be related to, and consequently resemble, the common progenitor of groups, since {345} become widely divergent. Extinct forms are seldom directly intermediate between existing forms; but are intermediate only by a long and circuitous course through many extinct and very different forms. We can clearly see why the organic remains of closely consecutive formations are more closely allied to each other, than are those of remote formations; for the forms are more closely linked together by generation: we can clearly see why the remains of an intermediate formation are intermediate in character. The inhabitants of each successive period in the world's history have beaten their predecessors in the race for life, and are, in so far, higher in the scale of nature; and this may account for that vague yet ill-defined sentiment, felt by many palæontologists, that organisation on the whole has progressed. If it should hereafter be proved that ancient animals resemble to a certain extent the embryos of more recent animals of the same class, the fact will be intelligible. The succession of the same types of structure within the same areas during the later geological periods ceases to be mysterious, and is simply explained by inheritance. If then the geological record be as imperfect as I believe it to be, and it may at least be asserted that the record cannot be proved to be much more perfect, the main objections to the theory of natural selection are greatly diminished or disappear. On the other hand, all the chief laws of palæontology plainly proclaim, as it seems to me, that species have been produced by ordinary generation: old forms having been supplanted by new and improved forms of life, produced by the laws of variation still acting round us, and preserved by Natural Selection. * * * * * {346} CHAPTER XI. GEOGRAPHICAL DISTRIBUTION. Present distribution cannot be accounted for by differences in physical conditions--Importance of barriers--Affinity of the productions of the same continent--Centres of creation--Means of dispersal, by changes of climate and of the level of the land, and by occasional means--Dispersal during the Glacial period co-extensive with the world. In considering the distribution of organic beings over the face of the globe, the first great fact which strikes us is, that neither the similarity nor the dissimilarity of the inhabitants of various regions can be accounted for by their climatal and other physical conditions. Of late, almost every author who has studied the subject has come to this conclusion. The case of America alone would almost suffice to prove its truth: for if we exclude the northern parts where the circumpolar land is almost continuous, all authors agree that one of the most fundamental divisions in geographical distribution is that between the New and Old Worlds; yet if we travel over the vast American continent, from the central parts of the United States to its extreme southern point, we meet with the most diversified conditions; the most humid districts, arid deserts, lofty mountains, grassy plains, forests, marshes, lakes, and great rivers, under almost every temperature. There is hardly a climate or condition in the Old World which cannot be paralleled in the New--at least as closely as the same species generally require; for it is a most rare case to find a group of organisms confined to any small spot, having conditions peculiar in only a slight {347} degree; for instance, small areas in the Old World could be pointed out hotter than any in the New World, yet these are not inhabited by a peculiar fauna or flora. Notwithstanding this parallelism in the conditions of the Old and New Worlds, how widely different are their living productions! In the southern hemisphere, if we compare large tracts of land in Australia, South Africa, and western South America, between latitudes 25° and 35°, we shall find parts extremely similar in all their conditions, yet it would not be possible to point out three faunas and floras more utterly dissimilar. Or again we may compare the productions of South America south of lat. 35° with those north of 25°, which consequently inhabit a considerably different climate, and they will be found incomparably more closely related to each other, than they are to the productions of Australia or Africa under nearly the same climate. Analogous facts could be given with respect to the inhabitants of the sea. A second great fact which strikes us in our general review is, that barriers of any kind, or obstacles to free migration, are related in a close and important manner to the differences between the productions of various regions. We see this in the great difference of nearly all the terrestrial productions of the New and Old Worlds, excepting in the northern parts, where the land almost joins, and where, under a slightly different climate, there might have been free migration for the northern temperate forms, as there now is for the strictly arctic productions. We see the same fact in the great difference between the inhabitants of Australia, Africa, and South America under the same latitude: for these countries are almost as much isolated from each other as is possible. On each continent, also, we see the same fact; for on the opposite sides of {348} lofty and continuous mountain-ranges, and of great deserts, and sometimes even of large rivers, we find different productions; though as mountain-chains, deserts, &c., are not as impassable, or likely to have endured so long as the oceans separating continents, the differences are very inferior in degree to those characteristic of distinct continents. Turning to the sea, we find the same law. No two marine faunas are more distinct, with hardly a fish, shell, or crab in common, than those of the eastern and western shores of South and Central America; yet these great faunas are separated only by the narrow, but impassable, isthmus of Panama. Westward of the shores of America, a wide space of open ocean extends, with not an island as a halting-place for emigrants; here we have a barrier of another kind, and as soon as this is passed we meet in the eastern islands of the Pacific, with another and totally distinct fauna. So that here three marine faunas range far northward and southward, in parallel lines not far from each other, under corresponding climates; but from being separated from each other by impassable barriers, either of land or open sea, they are wholly distinct. On the other hand, proceeding still further westward from the eastern islands of the tropical parts of the Pacific, we encounter no impassable barriers, and we have innumerable islands as halting-places, or continuous coasts, until after travelling over a hemisphere we come to the shores of Africa; and over this vast space we meet with no well-defined and distinct marine faunas. Although hardly one shell, crab or fish is common to the above-named three approximate faunas of Eastern and Western America and the eastern Pacific islands, yet many fish range from the Pacific into the Indian Ocean, and many shells are common to the eastern islands of the Pacific {349} and the eastern shores of Africa, on almost exactly opposite meridians of longitude. A third great fact, partly included in the foregoing statements, is the affinity of the productions of the same continent or sea, though the species themselves are distinct at different points and stations. It is a law of the widest generality, and every continent offers innumerable instances. Nevertheless the naturalist in travelling, for instance, from north to south never fails to be struck by the manner in which successive groups of beings, specifically distinct, yet clearly related, replace each other. He hears from closely allied, yet distinct kinds of birds, notes nearly similar, and sees their nests similarly constructed, but not quite alike, with eggs coloured in nearly the same manner. The plains near the Straits of Magellan are inhabited by one species of Rhea (American ostrich), and northward the plains of La Plata by another species of the same genus; and not by a true ostrich or emu, like those found in Africa and Australia under the same latitude. On these same plains of La Plata, we see the agouti and bizcacha, animals having nearly the same habits as our hares and rabbits and belonging to the same order of Rodents, but they plainly display an American type of structure. We ascend the lofty peaks of the Cordillera and we find an alpine species of bizcacha; we look to the waters, and we do not find the beaver or musk-rat, but the coypu and capybara, rodents of the American type. Innumerable other instances could be given. If we look to the islands off the American shore, however much they may differ in geological structure, the inhabitants, though they may be all peculiar species, are essentially American. We may look back to past ages, as shown in the last chapter, and we find American types then prevalent on {350} the American continent and in the American seas. We see in these facts some deep organic bond, prevailing throughout space and time, over the same areas of land and water, and independent of their physical conditions. The naturalist must feel little curiosity, who is not led to inquire what this bond is. This bond, on my theory, is simply inheritance, that cause which alone, as far as we positively know, produces organisms quite like, or, as we see in the case of varieties, nearly like each other. The dissimilarity of the inhabitants of different regions may be attributed to modification through natural selection, and in a quite subordinate degree to the direct influence of different physical conditions. The degree of dissimilarity will depend on the migration of the more dominant forms of life from one region into another having been effected with more or less ease, at periods more or less remote;--on the nature and number of the former immigrants;--and on their action and reaction, in their mutual struggles for life;--the relation of organism to organism being, as I have already often remarked, the most important of all relations. Thus the high importance of barriers comes into play by checking migration; as does time for the slow process of modification through natural selection. Widely-ranging species, abounding in individuals, which have already triumphed over many competitors in their own widely-extended homes will have the best chance of seizing on new places, when they spread into new countries. In their new homes they will be exposed to new conditions, and will frequently undergo further modification and improvement; and thus they will become still further victorious, and will produce groups of modified descendants. On this principle of inheritance with modification, we can understand how it is that sections of genera, whole genera, {351} and even families are confined to the same areas, as is so commonly and notoriously the case. I believe, as was remarked in the last chapter, in no law of necessary development. As the variability of each species is an independent property, and will be taken advantage of by natural selection, only so far as it profits the individual in its complex struggle for life, so the degree of modification in different species will be no uniform quantity. If, for instance, a number of species, which stand in direct competition with each other, migrate in a body into a new and afterwards isolated country, they will be little liable to modification; for neither migration nor isolation in themselves can do anything. These principles come into play only by bringing organisms into new relations with each other, and in a lesser degree with the surrounding physical conditions. As we have seen in the last chapter that some forms have retained nearly the same character from an enormously remote geological period, so certain species have migrated over vast spaces, and have not become greatly modified. On these views, it is obvious, that the several species of the same genus, though inhabiting the most distant quarters of the world, must originally have proceeded from the same source, as they have descended from the same progenitor. In the case of those species, which have undergone during whole geological periods but little modification, there is not much difficulty in believing that they may have migrated from the same region; for during the vast geographical and climatal changes which will have supervened since ancient times, almost any amount of migration is possible. But in many other cases, in which we have reason to believe that the species of a genus have been produced within comparatively recent times, there is great difficulty on this head. It {352} is also obvious that the individuals of the same species, though now inhabiting distant and isolated regions, must have proceeded from one spot, where their parents were first produced: for, as explained in the last chapter, it is incredible that individuals identically the same should ever have been produced through natural selection from parents specifically distinct. We are thus brought to the question which has been largely discussed by naturalists, namely, whether species have been created at one or more points of the earth's surface. Undoubtedly there are very many cases of extreme difficulty, in understanding how the same species could possibly have migrated from some one point to the several distant and isolated points, where now found. Nevertheless the simplicity of the view that each species was first produced within a single region captivates the mind. He who rejects it, rejects the _vera causa_ of ordinary generation with subsequent migration, and calls in the agency of a miracle. It is universally admitted, that in most cases the area inhabited by a species is continuous; and when a plant or animal inhabits two points so distant from each other, or with an interval of such a nature, that the space could not be easily passed over by migration, the fact is given as something remarkable and exceptional. The capacity of migrating across the sea is more distinctly limited in terrestrial mammals, than perhaps in any other organic beings; and, accordingly, we find no inexplicable cases of the same mammal inhabiting distant points of the world. No geologist will feel any difficulty in such cases as Great Britain having been formerly united to Europe, and consequently possessing the same quadrupeds. But if the same species can be produced at two separate points, why do we not find a single mammal common to Europe and {353} Australia or South America? The conditions of life are nearly the same, so that a multitude of European animals and plants have become naturalised in America and Australia; and some of the aboriginal plants are identically the same at these distant points of the northern and southern hemispheres? The answer, as I believe, is, that mammals have not been able to migrate, whereas some plants, from their varied means of dispersal, have migrated across the vast and broken interspace. The great and striking influence which barriers of every kind have had on distribution, is intelligible only on the view that the great majority of species have been produced on one side alone, and have not been able to migrate to the other side. Some few families, many sub-families, very many genera, and a still greater number of sections of genera are confined to a single region; and it has been observed by several naturalists, that the most natural genera, or those genera in which the species are most closely related to each other, are generally local, or confined to one area. What a strange anomaly it would be, if, when coming one step lower in the series, to the individuals of the same species, a directly opposite rule prevailed; and species were not local, but had been produced in two or more distinct areas! Hence it seems to me, as it has to many other naturalists, that the view of each species having been produced in one area alone, and having subsequently migrated from that area as far as its powers of migration and subsistence under past and present conditions permitted, is the most probable. Undoubtedly many cases occur, in which we cannot explain how the same species could have passed from one point to the other. But the geographical and climatal changes, which have certainly occurred within recent geological times, must have interrupted or rendered discontinuous the {354} formerly continuous range of many species. So that we are reduced to consider whether the exceptions to continuity of range are so numerous and of so grave a nature, that we ought to give up the belief, rendered probable by general considerations, that each species has been produced within one area, and has migrated thence as far as it could. It would be hopelessly tedious to discuss all the exceptional cases of the same species, now living at distant and separated points; nor do I for a moment pretend that any explanation could be offered of many such cases. But after some preliminary remarks, I will discuss a few of the most striking classes of facts; namely, the existence of the same species on the summits of distant mountain-ranges, and at distant points in the arctic and antarctic regions; and secondly (in the following chapter), the wide distribution of freshwater productions; and thirdly, the occurrence of the same terrestrial species on islands and on the mainland, though separated by hundreds of miles of open sea. If the existence of the same species at distant and isolated points of the earth's surface, can in many instances be explained on the view of each species having migrated from a single birthplace; then, considering our ignorance with respect to former climatal and geographical changes and various occasional means of transport, the belief that this has been the universal law, seems to me incomparably the safest. In discussing this subject, we shall be enabled at the same time to consider a point equally important for us, namely, whether the several distinct species of a genus, which on my theory have all descended from a common progenitor, can have migrated (undergoing modification during some part of their migration) from the area inhabited by their progenitor. If it can be shown to be almost invariably the case, that a region, of which {355} most of its inhabitants are closely related to, or belong to the same genera with the species of a second region, has probably received at some former period immigrants from this other region, my theory will be strengthened; for we can clearly understand, on the principle of modification, why the inhabitants of a region should be related to those of another region, whence it has been stocked. A volcanic island, for instance, upheaved and formed at the distance of a few hundreds of miles from a continent, would probably receive from it in the course of time a few colonists, and their descendants, though modified, would still be plainly related by inheritance to the inhabitants of the continent. Cases of this nature are common, and are, as we shall hereafter more fully see, inexplicable on the theory of independent creation. This view of the relation of species in one region to those in another, does not differ much (by substituting the word variety for species) from that lately advanced in an ingenious paper by Mr. Wallace, in which he concludes, that "every species has come into existence coincident both in space and time with a pre-existing closely allied species." And I now know from correspondence, that this coincidence he attributes to generation with modification. The previous remarks on "single and multiple centres of creation" do not directly bear on another allied question,--namely whether all the individuals of the same species have descended from a single pair, or single hermaphrodite, or whether, as some authors suppose, from many individuals simultaneously created. With those organic beings which never intercross (if such exist), the species, on my theory, must have descended from a succession of improved varieties, which will never have blended with other individuals or varieties, but will have supplanted each other; so that, at each {356} successive stage of modification and improvement, all the individuals of each variety will have descended from a single parent. But in the majority of cases, namely, with all organisms which habitually unite for each birth, or which often intercross, I believe that during the slow process of modification the individuals of the species will have been kept nearly uniform by intercrossing; so that many individuals will have gone on simultaneously changing, and the whole amount of modification will not have been due, at each stage, to descent from a single parent. To illustrate what I mean: our English racehorses differ slightly from the horses of every other breed; but they do not owe their difference and superiority to descent from any single pair, but to continued care in selecting and training many individuals during many generations. Before discussing the three classes of facts, which I have selected as presenting the greatest amount of difficulty on the theory of "single centres of creation," I must say a few words on the means of dispersal. _Means of Dispersal._--Sir C. Lyell and other authors have ably treated this subject. I can give here only the briefest abstract of the more important facts. Change of climate must have had a powerful influence on migration: a region when its climate was different may have been a high road for migration, but now be impassable; I shall, however, presently have to discuss this branch of the subject in some detail. Changes of level in the land must also have been highly influential: a narrow isthmus now separates two marine faunas; submerge it, or let it formerly have been submerged, and the two faunas will now blend or may formerly have blended: where the sea now extends, land may at a former period have connected islands or {357} possibly even continents together, and thus have allowed terrestrial productions to pass from one to the other. No geologist will dispute that great mutations of level have occurred within the period of existing organisms. Edward Forbes insisted that all the islands in the Atlantic must recently have been connected with Europe or Africa, and Europe likewise with America. Other authors have thus hypothetically bridged over every ocean, and have united almost every island to some mainland. If indeed the arguments used by Forbes are to be trusted, it must be admitted that scarcely a single island exists which has not recently been united to some continent. This view cuts the Gordian knot of the dispersal of the same species to the most distant points, and removes many a difficulty: but to the best of my judgment we are not authorized in admitting such enormous geographical changes within the period of existing species. It seems to me that we have abundant evidence of great oscillations of level in our continents; but not of such vast changes in their position and extension, as to have united them within the recent period to each other and to the several intervening oceanic islands. I freely admit the former existence of many islands, now buried beneath the sea, which may have served as halting places for plants and for many animals during their migration. In the coral-producing oceans such sunken islands are now marked, as I believe, by rings of coral or atolls standing over them. Whenever it is fully admitted, as I believe it will some day be, that each species has proceeded from a single birthplace, and when in the course of time we know something definite about the means of distribution, we shall be enabled to speculate with security on the former extension of the land. But I do not believe that it will ever be proved that within the {358} recent period continents which are now quite separate, have been continuously, or almost continuously, united with each other, and with the many existing oceanic islands. Several facts in distribution,--such as the great difference in the marine faunas on the opposite sides of almost every continent,--the close relation of the tertiary inhabitants of several lands and even seas to their present inhabitants,--a certain degree of relation (as we shall hereafter see) between the distribution of mammals and the depth of the sea,--these and other such facts seem to me opposed to the admission of such prodigious geographical revolutions within the recent period, as are necessitated on the view advanced by Forbes and admitted by his many followers. The nature and relative proportions of the inhabitants of oceanic islands likewise seem to me opposed to the belief of their former continuity with continents. Nor does their almost universally volcanic composition favour the admission that they are the wrecks of sunken continents;--if they had originally existed as mountain-ranges on the land, some at least of the islands would have been formed, like other mountain-summits, of granite, metamorphic schists, old fossiliferous or other such rocks, instead of consisting of mere piles of volcanic matter. I must now say a few words on what are called accidental means, but which more properly might be called occasional means of distribution. I shall here confine myself to plants. In botanical works, this or that plant is stated to be ill adapted for wide dissemination; but for transport across the sea, the greater or less facilities may be said to be almost wholly unknown. Until I tried, with Mr. Berkeley's aid, a few experiments, it was not even known how far seeds could resist the injurious action of sea-water. To my surprise I found that {359} out of 87 kinds, 64 germinated after an immersion of 28 days, and a few survived an immersion of 137 days. For convenience' sake I chiefly tried small seeds, without the capsule or fruit; and as all of these sank in a few days, they could not be floated across wide spaces of the sea, whether or not they were injured by the salt-water. Afterwards I tried some larger fruits, capsules, &c., and some of these floated for a long time. It is well known what a difference there is in the buoyancy of green and seasoned timber; and it occurred to me that floods might wash down plants or branches, and that these might be dried on the banks, and then by a fresh rise in the stream be washed into the sea. Hence I was led to dry stems and branches of 94 plants with ripe fruit, and to place them on sea-water. The majority sank quickly, but some which whilst green floated for a very short time, when dried floated much longer; for instance, ripe hazel-nuts sank immediately, but when dried they floated for 90 days, and afterwards when planted they germinated; an asparagus plant with ripe berries floated for 23 days, when dried it floated for 85 days, and the seeds afterwards germinated; the ripe seeds of Helosciadium sank in two days, when dried they floated for above 90 days, and afterwards germinated. Altogether out of the 94 dried plants, 18 floated for above 28 days, and some of the 18 floated for a very much longer period. So that as 64/87 seeds germinated after an immersion of 28 days; and as 18/94 plants with ripe fruit (but not all the same species as in the foregoing experiment) floated, after being dried, for above 28 days, as far as we may infer anything from these scanty facts, we may conclude that the seeds of 14/100 plants of any country might be floated by sea-currents during 28 days, and would retain their power of germination. In Johnston's Physical Atlas, the average {360} rate of the several Atlantic currents is 33 miles per diem (some currents running at the rate of 60 miles per diem); on this average, the seeds of 14/100 plants belonging to one country might be floated across 924 miles of sea to another country; and when stranded, if blown to a favourable spot by an inland gale, they would germinate. Subsequently to my experiments, M. Martens tried similar ones, but in a much better manner, for he placed the seeds in a box in the actual sea, so that they were alternately wet and exposed to the air like really floating plants. He tried 98 seeds, mostly different from mine; but he chose many large fruits and likewise seeds from plants which live near the sea; and this would have favoured the average length of their flotation and of their resistance to the injurious action of the salt-water. On the other hand he did not previously dry the plants or branches with the fruit; and this, as we have seen, would have caused some of them to have floated much longer. The result was that 18/98 of his seeds floated for 42 days, and were then capable of germination. But I do not doubt that plants exposed to the waves would float for a less time than those protected from violent movement as in our experiments. Therefore it would perhaps be safer to assume that the seeds of about 10/100 plants of a flora, after having been dried, could be floated across a space of sea 900 miles in width, and would then germinate. The fact of the larger fruits often floating longer than the small, is interesting; as plants with large seeds or fruit could hardly be transported by any other means; and Alph. de Candolle has shown that such plants generally have restricted ranges. But seeds may be occasionally transported in another manner. Drift timber is thrown up on most islands, {361} even on those in the midst of the widest oceans; and the natives of the coral-islands in the Pacific, procure stones for their tools, solely from the roots of drifted trees, these stones being a valuable royal tax. I find on examination, that when irregularly shaped stones are embedded in the roots of trees, small parcels of earth are very frequently enclosed in their interstices and behind them,--so perfectly that not a particle could be washed away in the longest transport: out of one small portion of earth thus _completely_ enclosed by wood in an oak about 50 years old, three dicotyledonous plants germinated: I am certain of the accuracy of this observation. Again, I can show that the carcasses of birds, when floating on the sea, sometimes escape being immediately devoured; and seeds of many kinds in the crops of floating birds long retain their vitality: peas and vetches, for instance, are killed by even a few days' immersion in sea-water; but some taken out of the crop of a pigeon, which had floated on artificial salt-water for 30 days, to my surprise nearly all germinated. Living birds can hardly fail to be highly effective agents in the transportation of seeds. I could give many facts showing how frequently birds of many kinds are blown by gales to vast distances across the ocean. We may I think safely assume that under such circumstances their rate of flight would often be 35 miles an hour; and some authors have given a far higher estimate. I have never seen an instance of nutritious seeds passing through the intestines of a bird; but hard seeds of fruit pass uninjured through even the digestive organs of a turkey. In the course of two months, I picked up in my garden 12 kinds of seeds, out of the excrement of small birds, and these seemed perfect, and some of them, which I tried, germinated. {362} But the following fact is more important: the crops of birds do not secrete gastric juice, and do not in the least injure, as I know by trial, the germination of seeds; now after a bird has found and devoured a large supply of food, it is positively asserted that all the grains do not pass into the gizzard for 12 or even 18 hours. A bird in this interval might easily be blown to the distance of 500 miles, and hawks are known to look out for tired birds, and the contents of their torn crops might thus readily get scattered. Mr. Brent informs me that a friend of his had to give up flying carrier-pigeons from France to England, as the hawks on the English coast destroyed so many on their arrival. Some hawks and owls bolt their prey whole, and after an interval of from twelve to twenty hours, disgorge pellets, which, as I know from experiments made in the Zoological Gardens, include seeds capable of germination. Some seeds of the oat, wheat, millet, canary, hemp, clover, and beet germinated after having been from twelve to twenty-one hours in the stomachs of different birds of prey; and two seeds of beet grew after having been thus retained for two days and fourteen hours. Freshwater fish, I find, eat seeds of many land and water plants: fish are frequently devoured by birds, and thus the seeds might be transported from place to place. I forced many kinds of seeds into the stomachs of dead fish, and then gave their bodies to fishing-eagles, storks, and pelicans; these birds after an interval of many hours, either rejected the seeds in pellets or passed them in their excrement; and several of these seeds retained their power of germination. Certain seeds, however, were always killed by this process. Although the beaks and feet of birds are generally quite clean, I can show that earth sometimes adheres to them: in one instance I removed twenty-two grains {363} of dry argillaceous earth from one foot of a partridge, and in this earth there was a pebble quite as large as the seed of a vetch. Thus seeds might occasionally be transported to great distances; for many facts could be given showing that soil almost everywhere is charged with seeds. Reflect for a moment on the millions of quails which annually cross the Mediterranean; and can we doubt that the earth adhering to their feet would sometimes include a few minute seeds? But I shall presently have to recur to this subject. As icebergs are known to be sometimes loaded with earth and stones, and have even carried brushwood, bones, and the nest of a land-bird, I can hardly doubt that they must occasionally have transported seeds from one part to another of the arctic and antarctic regions, as suggested by Lyell; and during the Glacial period from one part of the now temperate regions to another. In the Azores, from the large number of the species of plants common to Europe, in comparison with the plants of other oceanic islands nearer to the mainland, and (as remarked by Mr. H. C. Watson) from the somewhat northern character of the flora in comparison with the latitude, I suspected that these islands had been partly stocked by ice-borne seeds, during the Glacial epoch. At my request Sir C. Lyell wrote to M. Hartung to inquire whether he had observed erratic boulders on these islands, and he answered that he had found large fragments of granite and other rocks, which do not occur in the archipelago. Hence we may safely infer that icebergs formerly landed their rocky burthens on the shores of these mid-ocean islands, and it is at least possible that they may have brought thither the seeds of northern plants. Considering that the several above means of transport, and that several other means, which without {364} doubt remain to be discovered, have been in action year after year, for centuries and tens of thousands of years, it would I think be a marvellous fact if many plants had not thus become widely transported. These means of transport are sometimes called accidental, but this is not strictly correct: the currents of the sea are not accidental, nor is the direction of prevalent gales of wind. It should be observed that scarcely any means of transport would carry seeds for very great distances; for seeds do not retain their vitality when exposed for a great length of time to the action of sea-water; nor could they be long carried in the crops or intestines of birds. These means, however, would suffice for occasional transport across tracts of sea some hundred miles in breadth, or from island to island, or from a continent to a neighbouring island, but not from one distant continent to another. The floras of distant continents would not by such means become mingled in any great degree; but would remain as distinct as we now see them to be. The currents, from their course, would never bring seeds from North America to Britain, though they might and do bring seeds from the West Indies to our western shores, where, if not killed by so long an immersion in salt-water, they could not endure our climate. Almost every year, one or two land-birds are blown across the whole Atlantic Ocean, from North America to the western shores of Ireland and England; but seeds could be transported by these wanderers only by one means, namely, in dirt sticking to their feet, which is in itself a rare accident. Even in this case, how small would the chance be of a seed falling on favourable soil, and coming to maturity! But it would be a great error to argue that because a well-stocked island, like Great Britain, has not, as far as is known {365} (and it would be very difficult to prove this), received within the last few centuries, through occasional means of transport, immigrants from Europe or any other continent, that a poorly-stocked island, though standing more remote from the mainland, would not receive colonists by similar means. I do not doubt that out of twenty seeds or animals transported to an island, even if far less well-stocked than Britain, scarcely more than one would be so well fitted to its new home, as to become naturalised. But this, as it seems to me, is no valid argument against what would be effected by occasional means of transport, during the long lapse of geological time, whilst an island was being upheaved and formed, and before it had become fully stocked with inhabitants. On almost bare land, with few or no destructive insects or birds living there, nearly every seed, which chanced to arrive, if fitted for the climate, would be sure to germinate and survive. _Dispersal during the Glacial period._--The identity of many plants and animals, on mountain-summits, separated from each other by hundreds of miles of lowlands, where the Alpine species could not possibly exist, is one of the most striking cases known of the same species living at distant points, without the apparent possibility of their having migrated from one to the other. It is indeed a remarkable fact to see so many of the same plants living on the snowy regions of the Alps or Pyrenees, and in the extreme northern parts of Europe; but it is far more remarkable, that the plants on the White Mountains, in the United States of America, are all the same with those of Labrador, and nearly all the same, as we hear from Asa Gray, with those on the loftiest mountains of Europe. Even as long ago as 1747, such facts led Gmelin to conclude that the {366} same species must have been independently created at several distinct points; and we might have remained in this same belief, had not Agassiz and others called vivid attention to the Glacial period, which, as we shall immediately see, affords a simple explanation of these facts. We have evidence of almost every conceivable kind, organic and inorganic, that within a very recent geological period, central Europe and North America suffered under an Arctic climate. The ruins of a house burnt by fire do not tell their tale more plainly, than do the mountains of Scotland and Wales, with their scored flanks, polished surfaces, and perched boulders, of the icy streams with which their valleys were lately filled. So greatly has the climate of Europe changed, that in Northern Italy, gigantic moraines, left by old glaciers, are now clothed by the vine and maize. Throughout a large part of the United States, erratic boulders, and rocks scored by drifted icebergs and coast-ice, plainly reveal a former cold period. The former influence of the glacial climate on the distribution of the inhabitants of Europe, as explained with remarkable clearness by Edward Forbes, is substantially as follows. But we shall follow the changes more readily, by supposing a new glacial period to come slowly on, and then pass away, as formerly occurred. As the cold came on, and as each more southern zone became fitted for arctic beings and ill-fitted for their former more temperate inhabitants, the latter would be supplanted and arctic productions would take their places. The inhabitants of the more temperate regions would at the same time travel southward, unless they were stopped by barriers, in which case they would perish. The mountains would become covered with snow and ice, and their former Alpine inhabitants would descend to the plains. By the time that the cold had reached {367} its maximum, we should have a uniform arctic fauna and flora, covering the central parts of Europe, as far south as the Alps and Pyrenees, and even stretching into Spain. The now temperate regions of the United States would likewise be covered by arctic plants and animals, and these would be nearly the same with those of Europe; for the present circumpolar inhabitants, which we suppose to have everywhere travelled southward, are remarkably uniform round the world. We may suppose that the Glacial period came on a little earlier or later in North America than in Europe, so will the southern migration there have been a little earlier or later; but this will make no difference in the final result. As the warmth returned, the arctic forms would retreat northward, closely followed up in their retreat by the productions of the more temperate regions. And as the snow melted from the bases of the mountains, the arctic forms would seize on the cleared and thawed ground, always ascending higher and higher, as the warmth increased, whilst their brethren were pursuing their northern journey. Hence, when the warmth had fully returned, the same arctic species, which had lately lived in a body together on the lowlands of the Old and New Worlds, would be left isolated on distant mountain-summits (having been exterminated on all lesser heights) and in the arctic regions of both hemispheres. Thus we can understand the identity of many plants at points so immensely remote as on the mountains of the United States and of Europe. We can thus also understand the fact that the Alpine plants of each mountain-range are more especially related to the arctic forms living due north or nearly due north of them: for the migration as the cold came on, and the re-migration on the returning warmth, will generally {368} have been due south and north. The Alpine plants, for example, of Scotland, as remarked by Mr. H. C. Watson, and those of the Pyrenees, as remarked by Ramond, are more especially allied to the plants of northern Scandinavia; those of the United States to Labrador; those of the mountains of Siberia to the arctic regions of that country. These views, grounded as they are on the perfectly well-ascertained occurrence of a former Glacial period, seem to me to explain in so satisfactory a manner the present distribution of the Alpine and Arctic productions of Europe and America, that when in other regions we find the same species on distant mountain-summits, we may almost conclude without other evidence, that a colder climate permitted their former migration across the low intervening tracts, since become too warm for their existence. If the climate, since the Glacial period, has ever been in any degree warmer than at present (as some geologists in the United States believe to have been the case, chiefly from the distribution of the fossil Gnathodon), then the arctic and temperate productions will at a very late period have marched a little further north, and subsequently have retreated to their present homes; but I have met with no satisfactory evidence with respect to this intercalated slightly warmer period, since the Glacial period. The arctic forms, during their long southern migration and re-migration northward, will have been exposed to nearly the same climate, and, as is especially to be noticed, they will have kept in a body together; consequently their mutual relations will not have been much disturbed, and, in accordance with the principles inculcated in this volume, they will not have been liable to much modification. But with our Alpine productions, left isolated from the moment of the returning warmth, {369} first at the bases and ultimately on the summits of the mountains, the case will have been somewhat different; for it is not likely that all the same arctic species will have been left on mountain ranges distant from each other, and have survived there ever since; they will, also, in all probability have become mingled with ancient Alpine species, which must have existed on the mountains before the commencement of the Glacial epoch, and which during its coldest period will have been temporarily driven down to the plains; they will, also, have been exposed to somewhat different climatal influences. Their mutual relations will thus have been in some degree disturbed; consequently they will have been liable to modification; and this we find has been the case; for if we compare the present Alpine plants and animals of the several great European mountain-ranges, though very many of the species are identically the same, some present varieties, some are ranked as doubtful forms, and some few are distinct yet closely allied or representative species. In illustrating what, as I believe, actually took place during the Glacial period, I assumed that at its commencement the arctic productions were as uniform round the polar regions as they are at the present day. But the foregoing remarks on distribution apply not only to strictly arctic forms, but also to many sub-arctic and to some few northern temperate forms, for some of these are the same on the lower mountains and on the plains of North America and Europe; and it may be reasonably asked how I account for the necessary degree of uniformity of the sub-arctic and northern temperate forms round the world, at the commencement of the Glacial period. At the present day, the sub-arctic and northern temperate productions of the Old and New Worlds are separated from each other by the {370} Atlantic Ocean and by the extreme northern part of the Pacific. During the Glacial period, when the inhabitants of the Old and New Worlds lived further southwards than at present, they must have been still more completely separated by wider spaces of ocean. I believe the above difficulty may be surmounted by looking to still earlier changes of climate of an opposite nature. We have good reason to believe that during the newer Pliocene period, before the Glacial epoch, and whilst the majority of the inhabitants of the world were specifically the same as now, the climate was warmer than at the present day. Hence we may suppose that the organisms now living under the climate of latitude 60°, during the Pliocene period lived further north under the Polar Circle, in latitude 66°-67°; and that the strictly arctic productions then lived on the broken land still nearer to the pole. Now if we look at a globe, we shall see that under the Polar Circle there is almost continuous land from western Europe, through Siberia, to eastern America. And to this continuity of the circumpolar land, and to the consequent freedom for intermigration under a more favourable climate, I attribute the necessary amount of uniformity in the sub-arctic and northern temperate productions of the Old and New Worlds, at a period anterior to the Glacial epoch. Believing, from reasons before alluded to, that our continents have long remained in nearly the same relative position, though subjected to large, but partial oscillations of level, I am strongly inclined to extend the above view, and to infer that during some earlier and still warmer period, such as the older Pliocene period, a large number of the same plants and animals inhabited the almost continuous circumpolar land; and that these plants and animals, both in the Old and {371} New Worlds, began slowly to migrate southwards as the climate became less warm, long before the commencement of the Glacial period. We now see, as I believe, their descendants, mostly in a modified condition, in the central parts of Europe and the United States. On this view we can understand the relationship, with very little identity, between the productions of North America and Europe,--a relationship which is most remarkable, considering the distance of the two areas, and their separation by the Atlantic Ocean. We can further understand the singular fact remarked on by several observers, that the productions of Europe and America during the later tertiary stages were more closely related to each other than they are at the present time; for during these warmer periods the northern parts of the Old and New Worlds will have been almost continuously united by land, serving as a bridge, since rendered impassable by cold, for the intermigration of their inhabitants. During the slowly decreasing warmth of the Pliocene period, as soon as the species in common, which inhabited the New and Old Worlds, migrated south of the Polar Circle, they must have been completely cut off from each other. This separation, as far as the more temperate productions are concerned, took place long ages ago. And as the plants and animals migrated southward, they will have become mingled in the one great region with the native American productions, and have had to compete with them; and in the other great region, with those of the Old World. Consequently we have here everything favourable for much modification,--for far more modification than with the Alpine productions, left isolated, within a much more recent period, on the several mountain-ranges and on the arctic lands of the two Worlds. Hence it has come, that when we compare {372} the now living productions of the temperate regions of the New and Old Worlds, we find very few identical species (though Asa Gray has lately shown that more plants are identical than was formerly supposed), but we find in every great class many forms, which some naturalists rank as geographical races, and others as distinct species; and a host of closely allied or representative forms which are ranked by all naturalists as specifically distinct. As on the land, so in the waters of the sea, a slow southern migration of a marine fauna, which during the Pliocene or even a somewhat earlier period, was nearly uniform along the continuous shores of the Polar Circle, will account, on the theory of modification, for many closely allied forms now living in areas completely sundered. Thus, I think, we can understand the presence of many existing and tertiary representative forms on the eastern and western shores of temperate North America; and the still more striking case of many closely allied crustaceans (as described in Dana's admirable work), of some fish and other marine animals, in the Mediterranean and in the seas of Japan,--areas now separated by a continent and by nearly a hemisphere of equatorial ocean. These cases of relationship, without identity, of the inhabitants of seas now disjoined, and likewise of the past and present inhabitants of the temperate lands of North America and Europe, are inexplicable on the theory of creation. We cannot say that they have been created alike, in correspondence with the nearly similar physical conditions of the areas; for if we compare, for instance, certain parts of South America with the southern continents of the Old World, we see countries closely corresponding in all their physical conditions, but with their inhabitants utterly dissimilar. {373} But we must return to our more immediate subject, the Glacial period. I am convinced that Forbes's view may be largely extended. In Europe we have the plainest evidence of the cold period, from the western shores of Britain to the Oural range, and southward to the Pyrenees. We may infer from the frozen mammals and nature of the mountain vegetation, that Siberia was similarly affected. Along the Himalaya, at points 900 miles apart, glaciers have left the marks of their former low descent; and in Sikkim, Dr. Hooker saw maize growing on gigantic ancient moraines. South of the equator, we have some direct evidence of former glacial action in New Zealand; and the same plants, found on widely separated mountains in that island, tell the same story. If one account which has been published can be trusted, we have direct evidence of glacial action in the south-eastern corner of Australia. Looking to America; in the northern half, ice-borne fragments of rock have been observed on the eastern side as far south as lat. 36°-37°, and on the shores of the Pacific, where the climate is now so different, as far south as lat. 46°; erratic boulders have, also, been noticed on the Rocky Mountains. In the Cordillera of Equatorial South America, glaciers once extended far below their present level. In central Chili I was astonished at the structure of a vast mound of detritus, about 800 feet in height, crossing a valley of the Andes; and this I now feel convinced was a gigantic moraine, left far below any existing glacier. Further south on both sides of the continent, from lat. 41° to the southernmost extremity, we have the clearest evidence of former glacial action, in huge boulders transported far from their parent source. We do not know that the Glacial epoch was strictly simultaneous at these several far distant points on {374} opposite sides of the world. But we have good evidence in almost every case, that the epoch was included within the latest geological period. We have, also, excellent evidence, that it endured for an enormous time, as measured by years, at each point. The cold may have come on, or have ceased, earlier at one point of the globe than at another, but seeing that it endured for long at each, and that it was contemporaneous in a geological sense, it seems to me probable that it was, during a part at least of the period, actually simultaneous throughout the world. Without some distinct evidence to the contrary, we may at least admit as probable that the glacial action was simultaneous on the eastern and western sides of North America, in the Cordillera under the equator and under the warmer temperate zones, and on both sides of the southern extremity of the continent. If this be admitted, it is difficult to avoid believing that the temperature of the whole world was at this period simultaneously cooler. But it would suffice for my purpose, if the temperature was at the same time lower along certain broad belts of longitude. On this view of the whole world, or at least of broad longitudinal belts, having been simultaneously colder from pole to pole, much light can be thrown on the present distribution of identical and allied species. In America, Dr. Hooker has shown that between forty and fifty of the flowering plants of Tierra del Fuego, forming no inconsiderable part of its scanty flora, are common to Europe, enormously remote as these two points are; and there are many closely allied species. On the lofty mountains of equatorial America a host of peculiar species belonging to European genera occur. On the highest mountains of Brazil, some few European genera were found by Gardner, which do not exist in the wide {375} intervening hot countries. So on the Silla of Caraccas the illustrious Humboldt long ago found species belonging to genera characteristic of the Cordillera. On the mountains of Abyssinia, several European forms and some few representatives of the peculiar flora of the Cape of Good Hope occur. At the Cape of Good Hope a very few European species, believed not to have been introduced by man, and on the mountains, some few representative European forms are found, which have not been discovered in the intertropical parts of Africa. On the Himalaya, and on the isolated mountain-ranges of the peninsula of India, on the heights of Ceylon, and on the volcanic cones of Java, many plants occur, either identically the same or representing each other, and at the same time representing plants of Europe, not found in the intervening hot lowlands. A list of the genera collected on the loftier peaks of Java raises a picture of a collection made on a hill in Europe! Still more striking is the fact that southern Australian forms are clearly represented by plants growing on the summits of the mountains of Borneo. Some of these Australian forms, as I hear from Dr. Hooker, extend along the heights of the peninsula of Malacca, and are thinly scattered, on the one hand over India and on the other as far north as Japan. On the southern mountains of Australia, Dr. F. Müller has discovered several European species; other species, not introduced by man, occur on the lowlands; and a long list can be given, as I am informed by Dr. Hooker, of European genera, found in Australia, but not in the intermediate torrid regions. In the admirable 'Introduction to the Flora of New Zealand,' by Dr. Hooker, analogous and striking facts are given in regard to the plants of that large island. Hence we see that throughout the world, the plants growing on the {376} more lofty mountains, and on the temperate lowlands of the northern and southern hemispheres, are sometimes identically the same; but they are much oftener specifically distinct, though related to each other in a most remarkable manner. This brief abstract applies to plants alone: some strictly analogous facts could be given on the distribution of terrestrial animals. In marine productions, similar cases occur; as an example, I may quote a remark by the highest authority, Prof. Dana, that "it is certainly a wonderful fact that New Zealand should have a closer resemblance in its Crustacea to Great Britain, its antipode, than to any other part of the world." Sir J. Richardson, also, speaks of the reappearance on the shores of New Zealand, Tasmania, &c., of northern forms of fish. Dr. Hooker informs me that twenty-five species of Algæ are common to New Zealand and to Europe, but have not been found in the intermediate tropical seas. It should be observed that the northern species and forms found in the southern parts of the southern hemisphere, and on the mountain-ranges of the intertropical regions, are not arctic, but belong to the northern temperate zones. As Mr. H. C. Watson has recently remarked, "In receding from polar towards equatorial latitudes, the Alpine or mountain floras really become less and less arctic." Many of the forms living on the mountains of the warmer regions of the earth and in the southern hemisphere are of doubtful value, being ranked by some naturalists as specifically distinct, by others as varieties; but some are certainly identical, and many, though closely related to northern forms, must be ranked as distinct species. Now let us see what light can be thrown on the foregoing facts, on the belief, supported as it is by a large {377} body of geological evidence, that the whole world, or a large part of it, was during the Glacial period simultaneously much colder than at present. The Glacial period, as measured by years, must have been very long; and when we remember over what vast spaces some naturalised plants and animals have spread within a few centuries, this period will have been ample for any amount of migration. As the cold came slowly on, all the tropical plants and other productions will have retreated from both sides towards the equator, followed in the rear by the temperate productions, and these by the arctic; but with the latter we are not now concerned. The tropical plants probably suffered much extinction; how much no one can say; perhaps formerly the tropics supported as many species as we see at the present day crowded together at the Cape of Good Hope, and in parts of temperate Australia. As we know that many tropical plants and animals can withstand a considerable amount of cold, many might have escaped extermination during a moderate fall of temperature, more especially by escaping into the lowest, most protected, and warmest districts. But the great fact to bear in mind is, that all tropical productions will have suffered to a certain extent. On the other hand, the temperate productions, after migrating nearer to the equator, though they will have been placed under somewhat new conditions, will have suffered less. And it is certain that many temperate plants, if protected from the inroads of competitors, can withstand a much warmer climate than their own. Hence, it seems to me possible, bearing in mind that the tropical productions were in a suffering state and could not have presented a firm front against intruders, that a certain number of the more vigorous and dominant temperate forms might have penetrated the native ranks and have reached or {378} even crossed the equator. The invasion would, of course, have been greatly favoured by high land, and perhaps by a dry climate; for Dr. Falconer informs me that it is the damp with the heat of the tropics which is so destructive to perennial plants from a temperate climate. On the other hand, the most humid and hottest districts will have afforded an asylum to the tropical natives. The mountain-ranges north-west of the Himalaya, and the long line of the Cordillera, seem to have afforded two great lines of invasion: and it is a striking fact, lately communicated to me by Dr. Hooker, that all the flowering plants, about forty-six in number, common to Tierra del Fuego and to Europe still exist in North America, which must have lain on the line of march. But I do not doubt that some temperate productions entered and crossed even the _lowlands_ of the tropics at the period when the cold was most intense,--when arctic forms had migrated some twenty-five degrees of latitude from their native country and covered the land at the foot of the Pyrenees. At this period of extreme cold, I believe that the climate under the equator at the level of the sea was about the same with that now felt there at the height of six or seven thousand feet. During this the coldest period, I suppose that large spaces of the tropical lowlands were clothed with a mingled tropical and temperate vegetation, like that now growing with strange luxuriance at the base of the Himalaya, as graphically described by Hooker. Thus, as I believe, a considerable number of plants, a few terrestrial animals, and some marine productions, migrated during the Glacial period from the northern and southern temperate zones into the intertropical regions, and some even crossed the equator. As the warmth returned, these temperate forms would naturally ascend the higher mountains, being exterminated on the {379} lowlands; those which had not reached the equator would re-migrate northward or southward towards their former homes; but the forms, chiefly northern, which had crossed the equator, would travel still further from their homes into the more temperate latitudes of the opposite hemisphere. Although we have reason to believe from geological evidence that the whole body of arctic shells underwent scarcely any modification during their long southern migration and re-migration northward, the case may have been wholly different with those intruding forms which settled themselves on the intertropical mountains, and in the southern hemisphere. These being surrounded by strangers will have had to compete with many new forms of life; and it is probable that selected modifications in their structure, habits, and constitutions will have profited them. Thus many of these wanderers, though still plainly related by inheritance to their brethren of the northern or southern hemispheres, now exist in their new homes as well-marked varieties or as distinct species. It is a remarkable fact, strongly insisted on by Hooker in regard to America, and by Alph. de Candolle in regard to Australia, that many more identical plants and allied forms have apparently migrated from the north to the south, than in a reversed direction. We see, however, a few southern vegetable forms on the mountains of Borneo and Abyssinia. I suspect that this preponderant migration from north to south is due to the greater extent of land in the north, and to the northern forms having existed in their own homes in greater numbers, and having consequently been advanced through natural selection and competition to a higher stage of perfection or dominating power, than the southern forms. And thus, when they became commingled during the Glacial period, the northern forms {380} were enabled to beat the less powerful southern forms. Just in the same manner as we see at the present day, that very many European productions cover the ground in La Plata, and in a lesser degree in Australia, and have to a certain extent beaten the natives; whereas extremely few southern forms have become naturalised in any part of Europe, though hides, wool, and other objects likely to carry seeds have been largely imported into Europe during the last two or three centuries from La Plata, and during the last thirty or forty years from Australia. Something of the same kind must have occurred on the intertropical mountains: no doubt before the Glacial period they were stocked with endemic Alpine forms; but these have almost everywhere largely yielded to the more dominant forms, generated in the larger areas and more efficient workshops of the north. In many islands the native productions are nearly equalled or even outnumbered by the naturalised; and if the natives have not been actually exterminated, their numbers have been greatly reduced, and this is the first stage towards extinction. A mountain is an island on the land; and the intertropical mountains before the Glacial period must have been completely isolated; and I believe that the productions of these islands on the land yielded to those produced within the larger areas of the north, just in the same way as the productions of real islands have everywhere lately yielded to continental forms, naturalised by man's agency. I am far from supposing that all difficulties are removed on the view here given in regard to the range and affinities of the allied species which live in the northern and southern temperate zones and on the mountains of the intertropical regions. Very many difficulties remain to be solved. I do not pretend to {381} indicate the exact lines and means of migration, or the reason why certain species and not others have migrated; why certain species have been modified and have given rise to new groups of forms, and others have remained unaltered. We cannot hope to explain such facts, until we can say why one species and not another becomes naturalised by man's agency in a foreign land; why one ranges twice or thrice as far, and is twice or thrice as common, as another species within their own homes. I have said that many difficulties remain to be solved: some of the most remarkable are stated with admirable clearness by Dr. Hooker in his botanical works on the antarctic regions. These cannot be here discussed. I will only say that as far as regards the occurrence of identical species at points so enormously remote as Kerguelen Land, New Zealand, and Fuegia, I believe that towards the close of the Glacial period, icebergs, as suggested by Lyell, have been largely concerned in their dispersal. But the existence of several quite distinct species, belonging to genera exclusively confined to the south, at these and other distant points of the southern hemisphere, is, on my theory of descent with modification, a far more remarkable case of difficulty. For some of these species are so distinct, that we cannot suppose that there has been time since the commencement of the Glacial period for their migration, and for their subsequent modification to the necessary degree. The facts seem to me to indicate that peculiar and very distinct species have migrated in radiating lines from some common centre; and I am inclined to look in the southern, as in the northern hemisphere, to a former and warmer period, before the commencement of the Glacial period, when the antarctic lands, now covered with ice, supported a highly peculiar {382} and isolated flora. I suspect that before this flora was exterminated by the Glacial epoch, a few forms were widely dispersed to various points of the southern hemisphere by occasional means of transport, and by the aid, as halting-places, of existing and now sunken islands: By these means, as I believe, the southern shores of America, Australia, New Zealand, have become slightly tinted by the same peculiar forms of vegetable life. Sir C. Lyell in a striking passage has speculated, in language almost identical with mine, on the effects of great alternations of climate on geographical distribution. I believe that the world has recently felt one of his great cycles of change; and that on this view, combined with modification through natural selection, a multitude of facts in the present distribution both of the same and of allied forms of life can be explained. The living waters may be said to have flowed during one short period from the north and from the south, and to have crossed at the equator; but to have flowed with greater force from the north so as to have freely inundated the south. As the tide leaves its drift in horizontal lines, though rising higher on the shores where the tide rises highest, so have the living waters left their living drift on our mountain-summits, in a line gently rising from the arctic lowlands to a great height under the equator. The various beings thus left stranded may be compared with savage races of man, driven up and surviving in the mountain-fastnesses of almost every land, which serve as a record, full of interest to us, of the former inhabitants of the surrounding lowlands. * * * * * {383} CHAPTER XII. GEOGRAPHICAL DISTRIBUTION--_continued_. Distribution of fresh-water productions--On the inhabitants of oceanic islands--Absence of Batrachians and of terrestrial Mammals--On the relation of the inhabitants of islands to those of the nearest mainland--On colonisation from the nearest source with subsequent modification--Summary of the last and present chapters. As lakes and river-systems are separated from each other by barriers of land, it might have been thought that fresh-water productions would not have ranged widely within the same country, and as the sea is apparently a still more impassable barrier, that they never would have extended to distant countries. But the case is exactly the reverse. Not only have many fresh-water species, belonging to quite different classes, an enormous range, but allied species prevail in a remarkable manner throughout the world. I well remember, when first collecting in the fresh waters of Brazil, feeling much surprise at the similarity of the fresh-water insects, shells, &c., and at the dissimilarity of the surrounding terrestrial beings, compared with those of Britain. But this power in fresh-water productions of ranging widely, though so unexpected, can, I think, in most cases be explained by their having become fitted, in a manner highly useful to them, for short and frequent migrations from pond to pond, or from stream to stream; and liability to wide dispersal would follow from this capacity as an almost necessary consequence. We can here consider only a few cases. In regard to {384} fish, I believe that the same species never occur in the fresh waters of distant continents. But on the same continent the species often range widely and almost capriciously; for two river-systems will have some fish in common and some different. A few facts seem to favour the possibility of their occasional transport by accidental means; like that of the live fish not rarely dropped by whirlwinds in India, and the vitality of their ova when removed from the water. But I am inclined to attribute the dispersal of fresh-water fish mainly to slight changes within the recent period in the level of the land, having caused rivers to flow into each other. Instances, also, could be given of this having occurred during floods, without any change of level. We have evidence in the loess of the Rhine of considerable changes of level in the land within a very recent geological period, and when the surface was peopled by existing land and fresh-water shells. The wide difference of the fish on opposite sides of continuous mountain-ranges, which from an early period must have parted river-systems and completely prevented their inosculation, seems to lead to this same conclusion. With respect to allied fresh-water fish occurring at very distant points of the world, no doubt there are many cases which cannot at present be explained: but some fresh-water fish belong to very ancient forms, and in such cases there will have been ample time for great geographical changes, and consequently time and means for much migration. In the second place, salt-water fish can with care be slowly accustomed to live in fresh water; and, according to Valenciennes, there is hardly a single group of fishes confined exclusively to fresh water, so that we may imagine that a marine member of a fresh-water group might travel far along the shores of the sea, and {385} subsequently become modified and adapted to the fresh waters of a distant land. Some species of fresh-water shells have a very wide range, and allied species, which, on my theory, are descended from a common parent and must have proceeded from a single source, prevail throughout the world. Their distribution at first perplexed me much, as their ova are not likely to be transported by birds, and they are immediately killed by sea-water, as are the adults. I could not even understand how some naturalised species have rapidly spread throughout the same country. But two facts, which I have observed--and no doubt many others remain to be observed--throw some light on this subject. When a duck suddenly emerges from a pond covered with duck-weed, I have twice seen these little plants adhering to its back; and it has happened to me, in removing a little duckweed from one aquarium to another, that I have quite unintentionally stocked the one with fresh-water shells from the other. But another agency is perhaps more effectual: I suspended a duck's feet, which might represent those of a bird sleeping in a natural pond, in an aquarium, where many ova of fresh-water shells were hatching; and I found that numbers of the extremely minute and just-hatched shells crawled on the feet, and clung to them so firmly that when taken out of the water they could not be jarred off, though at a somewhat more advanced age they would voluntarily drop off. These just hatched molluscs, though aquatic in their nature, survived on the duck's feet, in damp air, from twelve to twenty hours; and in this length of time a duck or heron might fly at least six or seven hundred miles, and would be sure to alight on a pool or rivulet, if blown across sea to an oceanic island or to any other distant point. Sir Charles Lyell also {386} informs me that a Dyticus has been caught with an Ancylus (a fresh-water shell like a limpet) firmly adhering to it; and a water-beetle of the same family, a Colymbetes, once flew on board the 'Beagle,' when forty-five miles distant from the nearest land: how much farther it might have flown with a favouring gale no one can tell. With respect to plants, it has long been known what enormous ranges many fresh-water and even marsh-species have, both over continents and to the most remote oceanic islands. This is strikingly shown, as remarked by Alph. de Candolle, in large groups of terrestrial plants, which have only a very few aquatic members; for these latter seem immediately to acquire, as if in consequence, a very wide range. I think favourable means of dispersal explain this fact. I have before mentioned that earth occasionally, though rarely, adheres in some quantity to the feet and beaks of birds. Wading birds, which frequent the muddy edges of ponds, if suddenly flushed, would be the most likely to have muddy feet. Birds of this order I can show are the greatest wanderers, and are occasionally found on the most remote and barren islands in the open ocean; they would not be likely to alight on the surface of the sea, so that the dirt would not be washed off their feet; when making land, they would be sure to fly to their natural fresh-water haunts. I do not believe that botanists are aware how charged the mud of ponds is with seeds: I have tried several little experiments, but will here give only the most striking case: I took in February three table-spoonfuls of mud from three different points, beneath water, on the edge of a little pond; this mud when dry weighed only 6¾ ounces; I kept it covered up in my study for six months, pulling up and counting each plant as it grew; the plants were {387} of many kinds, and were altogether 537 in number; and yet the viscid mud was all contained in a breakfast cup! Considering these facts, I think it would be an inexplicable circumstance if water-birds did not transport the seeds of fresh-water plants to vast distances, and if consequently the range of these plants was not very great. The same agency may have come into play with the eggs of some of the smaller fresh-water animals. Other and unknown agencies probably have also played a part. I have stated that fresh-water fish eat some kinds of seeds, though they reject many other kinds after having swallowed them; even small fish swallow seeds of moderate size, as of the yellow water-lily and Potamogeton. Herons and other birds, century after century, have gone on daily devouring fish; they then take flight and go to other waters, or are blown across the sea; and we have seen that seeds retain their power of germination, when rejected in pellets or in excrement, many hours afterwards. When I saw the great size of the seeds of that fine water-lily, the Nelumbium, and remembered Alph. de Candolle's remarks on this plant, I thought that its distribution must remain quite inexplicable; but Audubon states that he found the seeds of the great southern water-lily (probably, according to Dr. Hooker, the Nelumbium luteum) in a heron's stomach; although I do not know the fact, yet analogy makes me believe that a heron flying to another pond and getting a hearty meal of fish, would probably reject from its stomach a pellet containing the seeds of the Nelumbium undigested; or the seeds might be dropped by the bird whilst feeding its young, in the same way as fish are known sometimes to be dropped. In considering these several means of distribution, {388} it should be remembered that when a pond or stream is first formed, for instance, on a rising islet, it will be unoccupied; and a single seed or egg will have a good chance of succeeding. Although there will always be a struggle for life between the individuals of the species, however few, already occupying any pond, yet as the number of kinds is small, compared with those on the land, the competition will probably be less severe between aquatic than between terrestrial species; consequently an intruder from the waters of a foreign country, would have a better chance of seizing on a place, than in the case of terrestrial colonists. We should, also, remember that some, perhaps many, freshwater productions are low in the scale of nature, and that we have reason to believe that such low beings change or become modified less quickly than the high; and this will give longer time than the average for the migration of the same aquatic species. We should not forget the probability of many species having formerly ranged as continuously as fresh-water productions ever can range, over immense areas, and having subsequently become extinct in intermediate regions. But the wide distribution of fresh-water plants and of the lower animals, whether retaining the same identical form or in some degree modified, I believe mainly depends on the wide dispersal of their seeds and eggs by animals, more especially by fresh-water birds, which have large powers of flight, and naturally travel from one to another and often distant piece of water. Nature, like a careful gardener, thus takes her seeds from a bed of a particular nature, and drops them in another equally well fitted for them. _On the Inhabitants of Oceanic Islands._--We now come to the last of the three classes of facts, which I {389} have selected as presenting the greatest amount of difficulty, on the view that all the individuals both of the same and of allied species have descended from a single parent; and therefore have all proceeded from a common birthplace, notwithstanding that in the course of time they have come to inhabit distant points of the globe. I have already stated that I cannot honestly admit Forbes's view on continental extensions, which, if legitimately followed out, would lead to the belief that within the recent period all existing islands have been nearly or quite joined to some continent. This view would remove many difficulties, but it would not, I think, explain all the facts in regard to insular productions. In the following remarks I shall not confine myself to the mere question of dispersal; but shall consider some other facts, which bear on the truth of the two theories of independent creation and of descent with modification. The species of all kinds which inhabit oceanic islands are few in number compared with those on equal continental areas: Alph. de Candolle admits this for plants, and Wollaston for insects. If we look to the large size and varied stations of New Zealand, extending over 780 miles of latitude, and compare its flowering plants, only 750 in number, with those on an equal area at the Cape of Good Hope or in Australia, we must, I think, admit that something quite independently of any difference in physical conditions has caused so great a difference in number. Even the uniform county of Cambridge has 847 plants, and the little island of Anglesea 764, but a few ferns and a few introduced plants are included in these numbers, and the comparison in some other respects is not quite fair. We have evidence that the barren island of Ascension aboriginally possessed under half-a-dozen flowering plants; {390} yet many have become naturalised on it, as they have on New Zealand and on every other oceanic island which can be named. In St. Helena there is reason to believe that the naturalised plants and animals have nearly or quite exterminated many native productions. He who admits the doctrine of the creation of each separate species, will have to admit, that a sufficient number of the best adapted plants and animals have not been created on oceanic islands; for man has unintentionally stocked them from various sources far more fully and perfectly than has nature. Although in oceanic islands the number of kinds of inhabitants is scanty, the proportion of endemic species (_i.e._ those found nowhere else in the world) is often extremely large. If we compare, for instance, the number of the endemic land-shells in Madeira, or of the endemic birds in the Galapagos Archipelago, with the number found on any continent, and then compare the area of the islands with that of the continent, we shall see that this is true. This fact might have been expected on my theory, for, as already explained, species occasionally arriving after long intervals in a new and isolated district, and having to compete with new associates, will be eminently liable to modification, and will often produce groups of modified descendants. But it by no means follows, that, because in an island nearly all the species of one class are peculiar, those of another class, or of another section of the same class, are peculiar; and this difference seems to depend partly on the species which do not become modified having immigrated with facility and in a body, so that their mutual relations have not been much disturbed; and partly on the frequent arrival of unmodified immigrants from the mother-country, and the consequent intercrossing with them. With respect to the effects of this intercrossing, {391} it should be remembered that the offspring of such crosses would almost certainly gain in vigour; so that even an occasional cross would produce more effect than might at first have been anticipated. To give a few examples: in the Galapagos Islands nearly every land-bird, but only two out of the eleven marine birds, are peculiar; and it is obvious that marine birds could arrive at these islands more easily than land-birds. Bermuda, on the other hand, which lies at about the same distance from North America as the Galapagos Islands do from South America, and which has a very peculiar soil, does not possess one endemic land-bird; and we know from Mr. J. M. Jones's admirable account of Bermuda, that very many North American birds, during their great annual migrations, visit either periodically or occasionally this island. Madeira does not possess one peculiar bird, and many European and African birds are almost every year blown there, as I am informed by Mr. E. V. Harcourt. So that these two islands of Bermuda and Madeira have been stocked by birds, which for long ages have struggled together in their former homes, and have become mutually adapted to each other; and when settled in their new homes, each kind will have been kept by the others to their proper places and habits, and will consequently have been little liable to modification. Any tendency to modification will, also, have been checked by intercrossing with the unmodified immigrants from the mother-country. Madeira, again, is inhabited by a wonderful number of peculiar land-shells, whereas not one species of sea-shell is confined to its shores: now, though we do not know how sea-shells are dispersed, yet we can see that their eggs or larvae, perhaps attached to seaweed or floating timber, or to the feet of wading-birds, might be transported far more easily than {392} land-shells, across three or four hundred miles of open sea. The different orders of insects in Madeira apparently present analogous facts. Oceanic islands are sometimes deficient in certain classes, and their places are apparently occupied by the other inhabitants; in the Galapagos Islands reptiles, and in New Zealand gigantic wingless birds, take the place of mammals. In the plants of the Galapagos Islands, Dr. Hooker has shown that the proportional numbers of the different orders are very different from what they are elsewhere. Such cases are generally accounted for by the physical conditions of the islands; but this explanation seems to me not a little doubtful. Facility of immigration, I believe, has been at least as important as the nature of the conditions. Many remarkable little facts could be given with respect to the inhabitants of remote islands. For instance, in certain islands not tenanted by mammals, some of the endemic plants have beautifully hooked seeds; yet few relations are more striking than the adaptation of hooked seeds for transportal by the wool and fur of quadrupeds. This case presents no difficulty on my view, for a hooked seed might be transported to an island by some other means; and the plant then becoming slightly modified, but still retaining its hooked seeds, would form an endemic species, having as useless an appendage as any rudimentary organ,--for instance, as the shrivelled wings under the soldered elytra of many insular beetles. Again, islands often possess trees or bushes belonging to orders which elsewhere include only herbaceous species; now trees, as Alph. de Candolle has shown, generally have, whatever the cause may be, confined ranges. Hence trees would be little likely to reach distant oceanic islands; and an herbaceous plant, though it would have no chance of {393} successfully competing in stature with a fully developed tree, when established on an island and having to compete with herbaceous plants alone, might readily gain an advantage by growing taller and taller and overtopping the other plants. If so, natural selection would often tend to add to the stature of herbaceous plants when growing on an oceanic island, to whatever order they belonged, and thus convert them first into bushes and ultimately into trees. With respect to the absence of whole orders on oceanic islands, Bory St. Vincent long ago remarked that Batrachians (frogs, toads, newts) have never been found on any of the many islands with which the great oceans are studded. I have taken pains to verify this assertion, and I have found it strictly true. I have, however, been assured that a frog exists on the mountains of the great island of New Zealand; but I suspect that this exception (if the information be correct) may be explained through glacial agency. This general absence of frogs, toads, and newts on so many oceanic islands cannot be accounted for by their physical conditions; indeed it seems that islands are peculiarly well fitted for these animals; for frogs have been introduced into Madeira, the Azores, and Mauritius, and have multiplied so as to become a nuisance. But as these animals and their spawn are known to be immediately killed by sea-water, on my view we can see that there would be great difficulty in their transportal across the sea, and therefore why they do not exist on any oceanic island. But why, on the theory of creation, they should not have been created there, it would be very difficult to explain. Mammals offer another and similar case. I have carefully searched the oldest voyages, but have not finished my search; as yet I have not found a single {394} instance, free from doubt, of a terrestrial mammal (excluding domesticated animals kept by the natives) inhabiting an island situated above 300 miles from a continent or great continental island; and many islands situated at a much less distance are equally barren. The Falkland Islands, which are inhabited by a wolf-like fox, come nearest to an exception; but this group cannot be considered as oceanic, as it lies on a bank connected with the mainland; moreover, icebergs formerly brought boulders to its western shores, and they may have formerly transported foxes, as so frequently now happens in the arctic regions. Yet it cannot be said that small islands will not support small mammals, for they occur in many parts of the world on very small islands, if close to a continent; and hardly an island can be named on which our smaller quadrupeds have not become naturalised and greatly multiplied. It cannot be said, on the ordinary view of creation, that there has not been time for the creation of mammals; many volcanic islands are sufficiently ancient, as shown by the stupendous degradation which they have suffered and by their tertiary strata: there has also been time for the production of endemic species belonging to other classes; and on continents it is thought that mammals appear and disappear at a quicker rate than other and lower animals. Though terrestrial mammals do not occur on oceanic islands, aërial mammals do occur on almost every island. New Zealand possesses two bats found nowhere else in the world: Norfolk Island, the Viti Archipelago, the Bonin Islands, the Caroline and Marianne Archipelagoes, and Mauritius, all possess their peculiar bats. Why, it may be asked, has the supposed creative force produced bats and no other mammals on remote islands? On my view this question can easily be answered; for no {395} terrestrial mammal can be transported across a wide space of sea, but bats can fly across. Bats have been seen wandering by day far over the Atlantic Ocean; and two North American species either regularly or occasionally visit Bermuda, at the distance of 600 miles from the mainland. I hear from Mr. Tomes, who has specially studied this family, that many of the same species have enormous ranges, and are found on continents and on far distant islands. Hence we have only to suppose that such wandering species have been modified through natural selection in their new homes in relation to their new position, and we can understand the presence of endemic bats on islands, with the absence of all terrestrial mammals. Besides the absence of terrestrial mammals in relation to the remoteness of islands from continents, there is also a relation, to a certain extent independent of distance, between the depth of the sea separating an island from the neighbouring mainland, and the presence in both of the same mammiferous species or of allied species in a more or less modified condition. Mr. Windsor Earl has made some striking observations on this head in regard to the great Malay Archipelago, which is traversed near Celebes by a space of deep ocean; and this space separates two widely distinct mammalian faunas. On either side the islands are situated on moderately deep submarine banks, and they are inhabited by closely allied or identical quadrupeds. No doubt some few anomalies occur in this great archipelago, and there is much difficulty in forming a judgment in some cases owing to the probable naturalisation of certain mammals through man's agency; but we shall soon have much light thrown on the natural history of this archipelago by the admirable zeal and researches of Mr. Wallace. I have not as yet had time to {396} follow up this subject in all other quarters of the world; but as far as I have gone, the relation generally holds good. We see Britain separated by a shallow channel from Europe, and the mammals are the same on both sides; we meet with analogous facts on many islands separated by similar channels from Australia. The West Indian Islands stand on a deeply submerged bank, nearly 1000 fathoms in depth, and here we find American forms, but the species and even the genera are distinct. As the amount of modification in all cases depends to a certain degree on the lapse of time, and as during changes of level it is obvious that islands separated by shallow channels are more likely to have been continuously united within a recent period to the mainland than islands separated by deeper channels, we can understand the frequent relation between the depth of the sea and the degree of affinity of the mammalian inhabitants of islands with those of a neighbouring continent,--an inexplicable relation on the view of independent acts of creation. All the foregoing remarks on the inhabitants of oceanic islands,--namely, the scarcity of kinds--the richness in endemic forms in particular classes or sections of classes,--the absence of whole groups, as of batrachians, and of terrestrial mammals notwithstanding the presence of aërial bats,--the singular proportions of certain orders of plants,--herbaceous forms having been developed into trees, &c.,--seem to me to accord better with the view of occasional means of transport having been largely efficient in the long course of time, than with the view of all our oceanic islands having been formerly connected by continuous land with the nearest continent; for on this latter view the migration would probably have been more complete; and if modification be admitted, all the forms of life would have been more {397} equally modified, in accordance with the paramount importance of the relation of organism to organism. I do not deny that there are many and grave difficulties in understanding how several of the inhabitants of the more remote islands, whether still retaining the same specific form or modified since their arrival, could have reached their present homes. But the probability of many islands having existed as halting-places, of which not a wreck now remains, must not be overlooked. I will here give a single instance of one of the cases of difficulty. Almost all oceanic islands, even the most isolated and smallest, are inhabited by land-shells, generally by endemic species, but sometimes by species found elsewhere. Dr. Aug. A. Gould has given several interesting cases in regard to the land-shells of the islands of the Pacific. Now it is notorious that land-shells are very easily killed by salt; their eggs, at least such as I have tried, sink in sea-water and are killed by it. Yet there must be, on my view, some unknown, but highly efficient means for their transportal. Would the just-hatched young occasionally crawl on and adhere to the feet of birds roosting on the ground, and thus get transported? It occurred to me that land-shells, when hybernating and having a membranous diaphragm over the mouth of the shell, might be floated in chinks of drifted timber across moderately wide arms of the sea. And I found that several species did in this state withstand uninjured an immersion in sea-water during seven days: one of these shells was the Helix pomatia, and after it had again hybernated I put it in sea-water for twenty days, and it perfectly recovered. As this species has a thick calcareous operculum, I removed it, and when it had formed a new membranous one, I immersed it for fourteen days in sea-water, and it recovered and crawled away: but more experiments are wanted on this head. {398} The most striking and important fact for us in regard to the inhabitants of islands, is their affinity to those of the nearest mainland, without being actually the same species. Numerous instances could be given of this fact. I will give only one, that of the Galapagos Archipelago, situated under the equator, between 500 and 600 miles from the shores of South America. Here almost every product of the land and water bears the unmistakeable stamp of the American continent. There are twenty-six land-birds, and twenty-five of these are ranked by Mr. Gould as distinct species, supposed to have been created here; yet the close affinity of most of these birds to American species in every character, in their habits, gestures, and tones of voice, was manifest. So it is with the other animals, and with nearly all the plants, as shown by Dr. Hooker in his admirable memoir on the Flora of this archipelago. The naturalist, looking at the inhabitants of these volcanic islands in the Pacific, distant several hundred miles from the continent, yet feels that he is standing on American land. Why should this be so? why should the species which are supposed to have been created in the Galapagos Archipelago, and nowhere else, bear so plain a stamp of affinity to those created in America? There is nothing in the conditions of life, in the geological nature of the islands, in their height or climate, or in the proportions in which the several classes are associated together, which resembles closely the conditions of the South American coast: in fact there is a considerable dissimilarity in all these respects. On the other hand, there is a considerable degree of resemblance in the volcanic nature of the soil, in climate, height, and size of the islands, between the Galapagos and Cape de Verde Archipelagos: but what an entire and absolute difference in their inhabitants! The inhabitants of the Cape de Verde Islands are related to {399} those of Africa, like those of the Galapagos to America. I believe this grand fact can receive no sort of explanation on the ordinary view of independent creation; whereas on the view here maintained, it is obvious that the Galapagos Islands would be likely to receive colonists, whether by occasional means of transport or by formerly continuous land, from America; and the Cape de Verde Islands from Africa; and that such colonists would be liable to modification;--the principle of inheritance still betraying their original birthplace. Many analogous facts could be given: indeed it is an almost universal rule that the endemic productions of islands are related to those of the nearest continent, or of other near islands. The exceptions are few, and most of them can be explained. Thus the plants of Kerguelen Land, though standing nearer to Africa than to America, are related, and that very closely, as we know from Dr. Hooker's account, to those of America: but on the view that this island has been mainly stocked by seeds brought with earth and stones on icebergs, drifted by the prevailing currents, this anomaly disappears. New Zealand in its endemic plants is much more closely related to Australia, the nearest mainland, than to any other region: and this is what might have been expected; but it is also plainly related to South America, which, although the next nearest continent, is so enormously remote, that the fact becomes an anomaly. But this difficulty almost disappears on the view that both New Zealand, South America, and other southern lands were long ago partially stocked from a nearly intermediate though distant point, namely from the antarctic islands, when they were clothed with vegetation, before the commencement of the Glacial period. The affinity, which, though feeble, I am assured by Dr. Hooker is real, between the flora of the south-western corner of Australia and of the Cape of Good {400} Hope, is a far more remarkable case, and is at present inexplicable: but this affinity is confined to the plants, and will, I do not doubt, be some day explained. The law which causes the inhabitants of an archipelago, though specifically distinct, to be closely allied to those of the nearest continent, we sometimes see displayed on a small scale, yet in a most interesting manner, within the limits of the same archipelago. Thus the several islands of the Galapagos Archipelago are tenanted, as I have elsewhere shown, in a quite marvellous manner, by very closely related species; so that the inhabitants of each separate island, though mostly distinct, are related in an incomparably closer degree to each other than to the inhabitants of any other part of the world. And this is just what might have been expected on my view, for the islands are situated so near each other that they would almost certainly receive immigrants from the same original source, or from each other. But this dissimilarity between the endemic inhabitants of the islands may be used as an argument against my views; for it may be asked, how has it happened in the several islands situated within sight of each other, having the same geological nature, the same height, climate, &c., that many of the immigrants should have been differently modified, though only in a small degree. This long appeared to me a great difficulty: but it arises in chief part from the deeply-seated error of considering the physical conditions of a country as the most important for its inhabitants; whereas it cannot, I think, be disputed that the nature of the other inhabitants, with which each has to compete, is as least as important, and generally a far more important element of success. Now if we look to those inhabitants of the Galapagos Archipelago which are found in other parts of the world (laying on one side for the moment the {401} endemic species, which cannot be here fairly included, as we are considering how they have come to be modified since their arrival), we find a considerable amount of difference in the several islands. This difference might indeed have been expected on the view of the islands having been stocked by occasional means of transport--a seed, for instance, of one plant having been brought to one island, and that of another plant to another island. Hence when in former times an immigrant settled on any one or more of the islands, or when it subsequently spread from one island to another, it would undoubtedly be exposed to different conditions of life in the different islands, for it would have to compete with different sets of organisms: a plant for instance, would find the best-fitted ground more perfectly occupied by distinct plants in one island than in another, and it would be exposed to the attacks of somewhat different enemies. If then it varied, natural selection would probably favour different varieties in the different islands. Some species, however, might spread and yet retain the same character throughout the group, just as we see on continents some species spreading widely and remaining the same. The really surprising fact in this case of the Galapagos Archipelago, and in a lesser degree in some analogous instances, is that the new species formed in the separate islands have not quickly spread to the other islands. But the islands, though in sight of each other, are separated by deep arms of the sea, in most cases wider than the British Channel, and there is no reason to suppose that they have at any former period been continuously united. The currents of the sea are rapid and sweep across the archipelago, and gales of wind are extraordinarily rare; so that the islands are far more effectually separated from each other than they appear to be on a map. Nevertheless a good many {402} species, both those found in other parts of the world and those confined to the archipelago, are common to the several islands, and we may infer from certain facts that these have probably spread from some one island to the others. But we often take, I think, an erroneous view of the probability of closely-allied species invading each other's territory, when put into free intercommunication. Undoubtedly if one species has any advantage whatever over another, it will in a very brief time wholly or in part supplant it; but if both are equally well fitted for their own places in nature, both probably will hold their own places and keep separate for almost any length of time. Being familiar with the fact that many species, naturalised through man's agency, have spread with astonishing rapidity over new countries, we are apt to infer that most species would thus spread; but we should remember that the forms which become naturalised in new countries are not generally closely allied to the aboriginal inhabitants, but are very distinct species, belonging in a large proportion of cases, as shown by Alph. de Candolle, to distinct genera. In the Galapagos Archipelago, many even of the birds, though so well adapted for flying from island to island, are distinct on each; thus there are three closely-allied species of mocking-thrush, each confined to its own island. Now let us suppose the mocking-thrush of Chatham Island to be blown to Charles Island, which has its own mocking-thrush: why should it succeed in establishing itself there? We may safely infer that Charles Island is well stocked with its own species, for annually more eggs are laid there than can possibly be reared; and we may infer that the mocking-thrush peculiar to Charles Island is at least as well fitted for its home as is the species peculiar to Chatham Island. Sir C. Lyell and Mr. Wollaston have communicated to me a remarkable fact bearing on this {403} subject; namely, that Madeira and the adjoining islet of Porto Santo possess many distinct but representative land-shells, some of which live in crevices of stone; and although large quantities of stone are annually transported from Porto Santo to Madeira, yet this latter island has not become colonised by the Porto Santo species: nevertheless both islands have been colonised by some European land-shells, which no doubt had some advantage over the indigenous species. From these considerations I think we need not greatly marvel at the endemic and representative species, which inhabit the several islands of the Galapagos Archipelago, not having universally spread from island to island. In many other instances, as in the several districts of the same continent, pre-occupation has probably played an important part in checking the commingling of species under the same conditions of life. Thus, the south-east and south-west corners of Australia have nearly the same physical conditions, and are united by continuous land, yet they are inhabited by a vast number of distinct mammals, birds, and plants. The principle which determines the general character of the fauna and flora of oceanic islands, namely, that the inhabitants, when not identically the same, yet are plainly related to the inhabitants of that region whence colonists could most readily have been derived,--the colonists having been subsequently modified and better fitted to their new homes,--is of the widest application throughout nature. We see this on every mountain, in every lake and marsh. For Alpine species, excepting in so far as the same forms, chiefly of plants, have spread widely throughout the world during the recent Glacial epoch, are related to those of the surrounding lowlands;--thus we have in South America, Alpine humming-birds, Alpine rodents, Alpine plants, {404} &c., all of strictly American forms, and it is obvious that a mountain, as it became slowly upheaved, would naturally be colonised from the surrounding lowlands. So it is with the inhabitants of lakes and marshes, excepting in so far as great facility of transport has given the same general forms to the whole world. We see this same principle in the blind animals inhabiting the caves of America and of Europe. Other analogous facts could be given. And it will, I believe, be universally found to be true, that wherever in two regions, let them be ever so distant, many closely-allied or representative species occur, there will likewise be found some identical species, showing, in accordance with the foregoing view, that at some former period there has been intercommunication or migration between the two regions. And wherever many closely-allied species occur, there will be found many forms which some naturalists rank as distinct species, and some as varieties; these doubtful forms showing us the steps in the process of modification. This relation between the power and extent of migration of a species, either at the present time or at some former period under different physical conditions, and the existence at remote points of the world of other species allied to it, is shown in another and more general way. Mr. Gould remarked to me long ago, that in those genera of birds which range over the world, many of the species have very wide ranges. I can hardly doubt that this rule is generally true, though it would be difficult to prove it. Amongst mammals, we see it strikingly displayed in Bats, and in a lesser degree in the Felidæ and Canidæ. We see it, if we compare the distribution of butterflies and beetles. So it is with most fresh-water productions, in which so many genera range over the world, and many individual species have {405} enormous ranges. It is not meant that in world-ranging genera all the species have a wide range, or even that they have on an _average_ a wide range; but only that some of the species range very widely; for the facility with which widely-ranging species vary and give rise to new forms will largely determine their average range. For instance, two varieties of the same species inhabit America and Europe, and the species thus has an immense range; but, if the variation had been a little greater, the two varieties would have been ranked as distinct species, and the common range would have been greatly reduced. Still less is it meant, that a species which apparently has the capacity of crossing barriers and ranging widely, as in the case of certain powerfully-winged birds, will necessarily range widely; for we should never forget that to range widely implies not only the power of crossing barriers, but the more important power of being victorious in distant lands in the struggle for life with foreign associates. But on the view of all the species of a genus having descended from a single parent, though now distributed to the most remote points of the world, we ought to find, and I believe as a general rule we do find, that some at least of the species range very widely; for it is necessary that the unmodified parent should range widely, undergoing modification during its diffusion, and should place itself under diverse conditions favourable for the conversion of its offspring, firstly into new varieties and ultimately into new species. In considering the wide distribution of certain genera, we should bear in mind that some are extremely ancient, and must have branched off from a common parent at a remote epoch; so that in such cases there will have been ample time for great climatal and geographical changes and for accidents of transport; and consequently for the migration of some of the species into all {406} quarters of the world, where they may have become slightly modified in relation to their new conditions. There is, also, some reason to believe from geological evidence that organisms low in the scale within each great class, generally change at a slower rate than the higher forms; and consequently the lower forms will have had a better chance of ranging widely and of still retaining the same specific character. This fact, together with the seeds and eggs of many low forms being very minute and better fitted for distant transportation, probably accounts for a law which has long been observed, and which has lately been admirably discussed by Alph. de Candolle in regard to plants, namely, that the lower any group of organisms is, the more widely it is apt to range. The relations just discussed,--namely, low and slowly-changing organisms ranging more widely than the high,--some of the species of widely-ranging genera themselves ranging widely,--such facts, as alpine, lacustrine, and marsh productions being related (with the exceptions before specified) to those on the surrounding low lands and dry lands, though these stations are so different,--the very close relation of the distinct species which inhabit the islets of the same archipelago,--and especially the striking relation of the inhabitants of each whole archipelago or island to those of the nearest mainland,--are, I think, utterly inexplicable on the ordinary view of the independent creation of each species, but are explicable on the view of colonisation from the nearest or readiest source, together with the subsequent modification and better adaptation of the colonists to their new homes. _Summary of last and present Chapters._--In these chapters I have endeavoured to show, that if we make due allowance for our ignorance of the full effects of all {407} the changes of climate and of the level of the land, which have certainly occurred within the recent period, and of other similar changes which may have occurred within the same period; if we remember how profoundly ignorant we are with respect to the many and curious means of occasional transport,--a subject which has hardly ever been properly experimentised on; if we bear in mind how often a species may have ranged continuously over a wide area, and then have become extinct in the intermediate tracts, I think the difficulties in believing that all the individuals of the same species, wherever located, have descended from the same parents, are not insuperable. And we are led to this conclusion, which has been arrived at by many naturalists under the designation of single centres of creation, by some general considerations, more especially from the importance of barriers and from the analogical distribution of sub-genera, genera, and families. With respect to the distinct species of the same genus, which on my theory must have spread from one parent-source; if we make the same allowances as before for our ignorance, and remember that some forms of life change most slowly, enormous periods of time being thus granted for their migration, I do not think that the difficulties are insuperable; though they often are in this case, and in that of the individuals of the same species, extremely great. As exemplifying the effects of climatal changes on distribution, I have attempted to show how important has been the influence of the modern Glacial period, which I am fully convinced simultaneously affected the whole world, or at least great meridional belts. As showing how diversified are the means of occasional transport, I have discussed at some little length the means of dispersal of fresh-water productions. {408} If the difficulties be not insuperable in admitting that in the long course of time the individuals of the same species, and likewise of allied species, have proceeded from some one source; then I think all the grand leading facts of geographical distribution are explicable on the theory of migration (generally of the more dominant forms of life), together with subsequent modification and the multiplication of new forms. We can thus understand the high importance of barriers, whether of land or water, which separate our several zoological and botanical provinces. We can thus understand the localisation of sub-genera, genera, and families; and how it is that under different latitudes, for instance in South America, the inhabitants of the plains and mountains, of the forests, marshes, and deserts, are in so mysterious a manner linked together by affinity, and are likewise linked to the extinct beings which formerly inhabited the same continent. Bearing in mind that the mutual relation of organism to organism is of the highest importance, we can see why two areas having nearly the same physical conditions should often be inhabited by very different forms of life; for according to the length of time which has elapsed since new inhabitants entered one region; according to the nature of the communication which allowed certain forms and not others to enter, either in greater or lesser numbers; according or not, as those which entered happened to come in more or less direct competition with each other and with the aborigines; and according as the immigrants were capable of varying more or less rapidly, there would ensue in different regions, independently of their physical conditions, infinitely diversified conditions of life,--there would be an almost endless amount of organic action and reaction,--and we should find, as we do find, some groups of beings greatly, and some only slightly modified,--some {409} developed in great force, some existing in scanty numbers--in the different great geographical provinces of the world. On these same principles, we can understand, as I have endeavoured to show, why oceanic islands should have few inhabitants, but of these a great number should be endemic or peculiar; and why, in relation to the means of migration, one group of beings, even within the same class, should have all its species endemic, and another group should have all its species common to other quarters of the world. We can see why whole groups of organisms, as batrachians and terrestrial mammals, should be absent from oceanic islands, whilst the most isolated islands possess their own peculiar species of aërial mammals or bats. We can see why there should be some relation between the presence of mammals, in a more or less modified condition, and the depth of the sea between an island and the mainland. We can clearly see why all the inhabitants of an archipelago, though specifically distinct on the several islets, should be closely related to each other, and likewise be related, but less closely, to those of the nearest continent or other source whence immigrants were probably derived. We can see why in two areas, however distant from each other, there should be a correlation, in the presence of identical species, of varieties, of doubtful species, and of distinct but representative species. As the late Edward Forbes often insisted, there is a striking parallelism in the laws of life throughout time and space: the laws governing the succession of forms in past times being nearly the same with those governing at the present time the differences in different areas. We see this in many facts. The endurance of each species and group of species is continuous in time; for the exceptions to the rule are so few, that they may {410} fairly be attributed to our not having as yet discovered in an intermediate deposit the forms which are therein absent, but which occur above and below: so in space, it certainly is the general rule that the area inhabited by a single species, or by a group of species, is continuous; and the exceptions, which are not rare, may, as I have attempted to show, be accounted for by migration at some former period under different conditions or by occasional means of transport, and by the species having become extinct in the intermediate tracts. Both in time and space, species and groups of species have their points of maximum development. Groups of species, belonging either to a certain period of time, or to a certain area, are often characterised by trifling characters in common, as of sculpture or colour. In looking to the long succession of ages, as in now looking to distant provinces throughout the world, we find that some organisms differ little, whilst others belonging to a different class, or to a different order, or even only to a different family of the same order, differ greatly. In both time and space the lower members of each class generally change less than the higher; but there are in both cases marked exceptions to the rule. On my theory these several relations throughout time and space are intelligible; for whether we look to the forms of life which have changed during successive ages within the same quarter of the world, or to those which have changed after having migrated into distant quarters, in both cases the forms within each class have been connected by the same bond of ordinary generation; and the more nearly any two forms are related in blood, the nearer they will generally stand to each other in time and space; in both cases the laws of variation have been the same, and modifications have been accumulated by the same power of natural selection. * * * * * {411} CHAPTER XIII. MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY: EMBRYOLOGY: RUDIMENTARY ORGANS. CLASSIFICATION, groups subordinate to groups--Natural system--Rules and difficulties in classification, explained on the theory of descent with modification--Classification of varieties--Descent always used in classification--Analogical or adaptive characters--Affinities, general, complex and radiating--Extinction separates and defines groups--MORPHOLOGY, between members of the same class, between parts of the same individual--EMBRYOLOGY, laws of, explained by variations not supervening at an early age, and being inherited at a corresponding age--RUDIMENTARY ORGANS; their origin explained--Summary. From the first dawn of life, all organic beings are found to resemble each other in descending degrees, so that they can be classed in groups under groups. This classification is evidently not arbitrary like the grouping of the stars in constellations. The existence of groups would have been of simple signification, if one group had been exclusively fitted to inhabit the land, and another the water; one to feed on flesh, another on vegetable matter, and so on; but the case is widely different in nature; for it is notorious how commonly members of even the same sub-group have different habits. In our second and fourth chapters, on Variation and on Natural Selection, I have attempted to show that it is the widely ranging, the much diffused and common, that is the dominant species belonging to the larger genera, which vary most. The varieties, or incipient species, thus produced ultimately become converted, as I believe, into new and distinct species; and these, on the principle of inheritance, tend to produce other new and dominant {412} species. Consequently the groups which are now large, and which generally include many dominant species, tend to go on increasing indefinitely in size. I further attempted to show that from the varying descendants of each species trying to occupy as many and as different places as possible in the economy of nature, there is a constant tendency in their characters to diverge. This conclusion was supported by looking at the great diversity of the forms of life which, in any small area, come into the closest competition, and by looking to certain facts in naturalisation. I attempted also to show that there is a constant tendency in the forms which are increasing in number and diverging in character, to supplant and exterminate the less divergent, the less improved, and preceding forms. I request the reader to turn to the diagram illustrating the action, as formerly explained, of these several principles; and he will see that the inevitable result is that the modified descendants proceeding from one progenitor become broken up into groups subordinate to groups. In the diagram each letter on the uppermost line may represent a genus including several species; and all the genera on this line form together one class, for all have descended from one ancient but unseen parent, and, consequently, have inherited something in common. But the three genera on the left hand have, on this same principle, much in common, and form a sub-family, distinct from that including the next two genera on the right hand, which diverged from a common parent at the fifth stage of descent. These five genera have also much, though less, in common; and they form a family distinct from that including the three genera still further to the right hand, which diverged at a still earlier period. And all these genera, descended from (A), form an order distinct from the {413} genera descended from (I). So that we here have many species descended from a single progenitor grouped into genera; and the genera are included in, or subordinate to, sub-families, families, and orders, all united into one class. Thus, the grand fact in natural history of the subordination of group under group, which, from its familiarity, does not always sufficiently strike us, is in my judgment explained. Naturalists try to arrange the species, genera, and families in each class, on what is called the Natural System. But what is meant by this system? Some authors look at it merely as a scheme for arranging together those living objects which are most alike, and for separating those which are most unlike; or as an artificial means for enunciating, as briefly as possible, general propositions,--that is, by one sentence to give the characters common, for instance, to all mammals, by another those common to all carnivora, by another those common to the dog-genus, and then by adding a single sentence, a full description is given of each kind of dog. The ingenuity and utility of this system are indisputable. But many naturalists think that something more is meant by the Natural System; they believe that it reveals the plan of the Creator; but unless it be specified whether order in time or space, or what else is meant by the plan of the Creator, it seems to me that nothing is thus added to our knowledge. Such expressions as that famous one of Linnæus, and which we often meet with in a more or less concealed form, that the characters do not make the genus, but that the genus gives the characters, seem to imply that something more is included in our classification, than mere resemblance. I believe that something more is included; and that propinquity of descent,--the only known cause of the similarity of organic beings,--is the bond, hidden as it is by various degrees of {414} modification, which is partially revealed to us by our classifications. Let us now consider the rules followed in classification, and the difficulties which are encountered on the view that classification either gives some unknown plan of creation, or is simply a scheme for enunciating general propositions and of placing together the forms most like each other. It might have been thought (and was in ancient times thought) that those parts of the structure which determined the habits of life, and the general place of each being in the economy of nature, would be of very high importance in classification. Nothing can be more false. No one regards the external similarity of a mouse to a shrew, of a dugong to a whale, of a whale to a fish, as of any importance. These resemblances, though so intimately connected with the whole life of the being, are ranked as merely "adaptive or analogical characters;" but to the consideration of these resemblances we shall have to recur. It may even be given as a general rule, that the less any part of the organisation is concerned with special habits, the more important it becomes for classification. As an instance: Owen, in speaking of the dugong, says, "The generative organs being those which are most remotely related to the habits and food of an animal, I have always regarded as affording very clear indications of its true affinities. We are least likely in the modifications of these organs to mistake a merely adaptive for an essential character." So with plants, how remarkable it is that the organs of vegetation, on which their whole life depends, are of little signification, excepting in the first main divisions; whereas the organs of reproduction, with their product the seed, are of paramount importance! We must not, therefore, in classifying, trust to resemblances in parts of the organisation, however important {415} they may be for the welfare of the being in relation to the outer world. Perhaps from this cause it has partly arisen, that almost all naturalists lay the greatest stress on resemblances in organs of high vital or physiological importance. No doubt this view of the classificatory importance of organs which are important is generally, but by no means always, true. But their importance for classification, I believe, depends on their greater constancy throughout large groups of species; and this constancy depends on such organs having generally been subjected to less change in the adaptation of the species to their conditions of life. That the mere physiological importance of an organ does not determine its classificatory value, is almost shown by the one fact, that in allied groups, in which the same organ, as we have every reason to suppose, has nearly the same physiological value, its classificatory value is widely different. No naturalist can have worked at any group without being struck with this fact; and it has been fully acknowledged in the writings of almost every author. It will suffice to quote the highest authority, Robert Brown, who in speaking of certain organs in the Proteaceæ, says their generic importance, "like that of all their parts, not only in this but, as I apprehend, in every natural family, is very unequal, and in some cases seems to be entirely lost." Again in another work he says, the genera of the Connaraceæ "differ in having one or more ovaria, in the existence or absence of albumen, in the imbricate or valvular æstivation. Any one of these characters singly is frequently of more than generic importance, though here even when all taken together they appear insufficient to separate Cnestis from Connarus." To give an example amongst insects, in one great division of the Hymenoptera, the antennæ, as Westwood has remarked, are most constant in structure; {416} in another division they differ much, and the differences are of quite subordinate value in classification; yet no one probably will say that the antennae in these two divisions of the same order are of unequal physiological importance. Any number of instances could be given of the varying importance for classification of the same important organ within the same group of beings. Again, no one will say that rudimentary or atrophied organs are of high physiological or vital importance; yet, undoubtedly, organs in this condition are often of high value in classification. No one will dispute that the rudimentary teeth in the upper jaws of young ruminants, and certain rudimentary bones of the leg, are highly serviceable in exhibiting the close affinity between Ruminants and Pachyderms. Robert Brown has strongly insisted on the fact that the rudimentary florets are of the highest importance in the classification of the Grasses. Numerous instances could be given of characters derived from parts which must be considered of very trifling physiological importance, but which are universally admitted as highly serviceable in the definition of whole groups. For instance, whether or not there is an open passage from the nostrils to the mouth, the only character, according to Owen, which absolutely distinguishes fishes and reptiles--the inflection of the angle of the jaws in Marsupials--the manner in which the wings of insects are folded--mere colour in certain Algæ--mere pubescence on parts of the flower in grasses--the nature of the dermal covering, as hair or feathers, in the Vertebrata. If the Ornithorhynchus had been covered with feathers instead of hair, this external and trifling character would, I think, have been considered by naturalists as important an aid in determining the degree of affinity of this strange creature to {417} birds and reptiles, as an approach in structure in any one internal and important organ. The importance, for classification, of trifling characters, mainly depends on their being correlated with several other characters of more or less importance. The value indeed of an aggregate of characters is very evident in natural history. Hence, as has often been remarked, a species may depart from its allies in several characters, both of high physiological importance and of almost universal prevalence, and yet leave us in no doubt where it should be ranked. Hence, also, it has been found, that a classification founded on any single character, however important that may be, has always failed; for no part of the organisation is universally constant. The importance of an aggregate of characters, even when none are important, alone explains, I think, that saying of Linnæus, that the characters do not give the genus, but the genus gives the characters; for this saying seems founded on an appreciation of many trifling points of resemblance, too slight to be defined. Certain plants, belonging to the Malpighiaceæ, bear perfect and degraded flowers; in the latter, as A. de Jussieu has remarked, "the greater number of the characters proper to the species, to the genus, to the family, to the class, disappear, and thus laugh at our classification." But when Aspicarpa produced in France, during several years, only degraded flowers, departing so wonderfully in a number of the most important points of structure from the proper type of the order, yet M. Richard sagaciously saw, as Jussieu observes, that this genus should still be retained amongst the Malpighiaceæ. This case seems to me well to illustrate the spirit with which our classifications are sometimes necessarily founded. Practically when naturalists are at work, they do {418} not trouble themselves about the physiological value of the characters which they use in defining a group, or in allocating any particular species. If they find a character nearly uniform, and common to a great number of forms, and not common to others, they use it as one of high value; if common to some lesser number, they use it as of subordinate value. This principle has been broadly confessed by some naturalists to be the true one; and by none more clearly than by that excellent botanist, Aug. St. Hilaire. If certain characters are always found correlated with others, though no apparent bond of connexion can be discovered between them, especial value is set on them. As in most groups of animals, important organs, such as those for propelling the blood, or for aërating it, or those for propagating the race, are found nearly uniform, they are considered as highly serviceable in classification; but in some groups of animals all these, the most important vital organs, are found to offer characters of quite subordinate value. We can see why characters derived from the embryo should be of equal importance with those derived from the adult, for our classifications of course include all ages of each species. But it is by no means obvious, on the ordinary view, why the structure of the embryo should be more important for this purpose than that of the adult, which alone plays its full part in the economy of nature. Yet it has been strongly urged by those great naturalists, Milne Edwards and Agassiz, that embryonic characters are the most important of any in the classification of animals; and this doctrine has very generally been admitted as true. The same fact holds good with flowering plants, of which the two main divisions have been founded on characters derived from the embryo,--on the number and position of the {419} embryonic leaves or cotyledons, and on the mode of development of the plumule and radicle. In our discussion on embryology, we shall see why such characters are so valuable, on the view of classification tacitly including the idea of descent. Our classifications are often plainly influenced by chains of affinities. Nothing can be easier than to define a number of characters common to all birds; but in the case of crustaceans, such definition has hitherto been found impossible. There are crustaceans at the opposite ends of the series, which have hardly a character in common; yet the species at both ends, from being plainly allied to others, and these to others, and so onwards, can be recognised as unequivocally belonging to this, and to no other class of the Articulata. Geographical distribution has often been used, though perhaps not quite logically, in classification, more especially in very large groups of closely allied forms. Temminck insists on the utility or even necessity of this practice in certain groups of birds; and it has been followed by several entomologists and botanists. Finally, with respect to the comparative value of the various groups of species, such as orders, sub-orders, families, sub-families, and genera, they seem to be, at least at present, almost arbitrary. Several of the best botanists, such as Mr. Bentham and others, have strongly insisted on their arbitrary value. Instances could be given amongst plants and insects, of a group of forms, first ranked by practised naturalists as only a genus, and then raised to the rank of a sub-family or family; and this has been done, not because further research has detected important structural differences, at first overlooked, but because numerous allied species, with slightly different grades of difference, have been subsequently discovered. {420} All the foregoing rules and aids and difficulties in classification are explained, if I do not greatly deceive myself, on the view that the natural system is founded on descent with modification; that the characters which naturalists consider as showing true affinity between any two or more species, are those which have been inherited from a common parent, and, in so far, all true classification is genealogical; that community of descent is the hidden bond which naturalists have been unconsciously seeking, and not some unknown plan of creation, or the enunciation of general propositions, and the mere putting together and separating objects more or less alike. But I must explain my meaning more fully. I believe that the _arrangement_ of the groups within each class, in due subordination and relation to the other groups, must be strictly genealogical in order to be natural; but that the _amount_ of difference in the several branches or groups, though allied in the same degree in blood to their common progenitor, may differ greatly, being due to the different degrees of modification which they have undergone; and this is expressed by the forms being ranked under different genera, families, sections, or orders. The reader will best understand what is meant, if he will take the trouble of referring to the diagram in the fourth chapter. We will suppose the letters A to L to represent allied genera, which lived during the Silurian epoch, and these have descended from a species which existed at an unknown anterior period. Species of three of these genera (A, F, and I) have transmitted modified descendants to the present day, represented by the fifteen genera (a^{14} to z^{14}) on the uppermost horizontal line. Now all these modified descendants from a single species, are represented as related in blood or descent to the same {421} degree; they may metaphorically be called cousins to the same millionth degree; yet they differ widely and in different degrees from each other. The forms descended from A, now broken up into two or three families, constitute a distinct order from those descended from I, also broken up into two families. Nor can the existing species, descended from A, be ranked in the same genus with the parent A; or those from I, with the parent I. But the existing genus F^{14} may be supposed to have been but slightly modified; and it will then rank with the parent-genus F; just as some few still living organic beings belong to Silurian genera. So that the amount or value of the differences between organic beings all related to each other in the same degree in blood, has come to be widely different. Nevertheless their genealogical _arrangement_ remains strictly true, not only at the present time, but at each successive period of descent. All the modified descendants from A will have inherited something in common from their common parent, as will all the descendants from I; so will it be with each subordinate branch of descendants, at each successive period. If, however, we choose to suppose that any of the descendants of A or of I have been so much modified as to have more or less completely lost traces of their parentage, in this case, their places in a natural classification will have been more or less completely lost,--as sometimes seems to have occurred with existing organisms. All the descendants of the genus F, along its whole line of descent, are supposed to have been but little modified, and they yet form a single genus. But this genus, though much isolated, will still occupy its proper intermediate position; for F originally was intermediate in character between A and I, and the several genera descended from these two genera will {422} have inherited to a certain extent their characters. This natural arrangement is shown, as far as is possible on paper, in the diagram, but in much too simple a manner. If a branching diagram had not been used, and only the names of the groups had been written in a linear series, it would have been still less possible to have given a natural arrangement; and it is notoriously not possible to represent in a series, on a flat surface, the affinities which we discover in nature amongst the beings of the same group. Thus, on the view which I hold, the natural system is genealogical in its arrangement, like a pedigree; but the degrees of modification which the different groups have undergone, have to be expressed by ranking them under different so-called genera, sub-families, families, sections, orders, and classes. It may be worth while to illustrate this view of classification, by taking the case of languages. If we possessed a perfect pedigree of mankind, a genealogical arrangement of the races of man would afford the best classification of the various languages now spoken throughout the world; and if all extinct languages, and all intermediate and slowly changing dialects, had to be included, such an arrangement would, I think, be the only possible one. Yet it might be that some very ancient language had altered little, and had given rise to few new languages, whilst others (owing to the spreading and subsequent isolation and states of civilisation of the several races, descended from a common race) had altered much, and had given rise to many new languages and dialects. The various degrees of difference in the languages from the same stock, would have to be expressed by groups subordinate to groups; but the proper or even only possible arrangement would still be genealogical; and this would be strictly natural, as {423} it would connect together all languages, extinct and modern, by the closest affinities, and would give the filiation and origin of each tongue. In confirmation of this view, let us glance at the classification of varieties, which are believed or known to have descended from one species. These are grouped under species, with sub-varieties under varieties; and with our domestic productions, several other grades of difference are requisite, as we have seen with pigeons. The origin of the existence of groups subordinate to groups, is the same with varieties as with species, namely, closeness of descent with various degrees of modification. Nearly the same rules are followed in classifying varieties, as with species. Authors have insisted on the necessity of classing varieties on a natural instead of an artificial system; we are cautioned, for instance, not to class two varieties of the pine-apple together, merely because their fruit, though the most important part, happens to be nearly identical; no one puts the swedish and common turnips together, though the esculent and thickened stems are so similar. Whatever part is found to be most constant, is used in classing varieties: thus the great agriculturist Marshall says the horns are very useful for this purpose with cattle, because they are less variable than the shape or colour of the body, &c.; whereas with sheep the horns are much less serviceable, because less constant. In classing varieties, I apprehend if we had a real pedigree, a genealogical classification would be universally preferred; and it has been attempted by some authors. For we might feel sure, whether there had been more or less modification, the principle of inheritance would keep the forms together which were allied in the greatest number of points. In tumbler pigeons, though some sub-varieties differ from the others {424} in the important character of having a longer beak, yet all are kept together from having the common habit of tumbling; but the short-faced breed has nearly or quite lost this habit; nevertheless, without any reasoning or thinking on the subject, these tumblers are kept in the same group, because allied in blood and alike in some other respects. If it could be proved that the Hottentot had descended from the Negro, I think he would be classed under the Negro group, however much he might differ in colour and other important characters from negroes. With species in a state of nature, every naturalist has in fact brought descent into his classification; for he includes in his lowest grade, or that of a species, the two sexes; and how enormously these sometimes differ in the most important characters, is known to every naturalist: scarcely a single fact can be predicated in common of the males and hermaphrodites of certain cirripedes, when adult, and yet no one dreams of separating them. The naturalist includes as one species the several larval stages of the same individual, however much they may differ from each other and from the adult; as he likewise includes the so-called alternate generations of Steenstrup, which can only in a technical sense be considered as the same individual. He includes monsters; he includes varieties, not solely because they closely resemble the parent-form, but because they are descended from it. He who believes that the cowslip is descended from the primrose, or conversely, ranks them together as a single species, and gives a single definition. As soon as three Orchidean forms (Monochanthus, Myanthus, and Catasetum), which had previously been ranked as three distinct genera, were known to be sometimes produced on the same spike, they were immediately included as a single species. {425} As descent has universally been used in classing together the individuals of the same species, though the males and females and larvæ are sometimes extremely different; and as it has been used in classing varieties which have undergone a certain, and sometimes a considerable amount of modification, may not this same element of descent have been unconsciously used in grouping species under genera, and genera under higher groups, though in these cases the modification has been greater in degree, and has taken a longer time to complete? I believe it has thus been unconsciously used; and only thus can I understand the several rules and guides which have been followed by our best systematists. We have no written pedigrees; we have to make out community of descent by resemblances of any kind. Therefore we choose those characters which, as far as we can judge, are the least likely to have been modified in relation to the conditions of life to which each species has been recently exposed. Rudimentary structures on this view are as good as, or even sometimes better than, other parts of the organisation. We care not how trifling a character may be--let it be the mere inflection of the angle of the jaw, the manner in which an insect's wing is folded, whether the skin be covered by hair or feathers--if it prevail throughout many and different species, especially those having very different habits of life, it assumes high value; for we can account for its presence in so many forms with such different habits, only by its inheritance from a common parent. We may err in this respect in regard to single points of structure, but when several characters, let them be ever so trifling, occur together throughout a large group of beings having different habits, we may feel almost sure, on the theory of descent, that these characters have been inherited from a common ancestor. {426} And we know that such correlated or aggregated characters have especial value in classification. We can understand why a species or a group of species may depart, in several of its most important characteristics, from its allies, and yet be safely classed with them. This may be safely done, and is often done, as long as a sufficient number of characters, let them be ever so unimportant, betrays the hidden bond of community of descent. Let two forms have not a single character in common, yet if these extreme forms are connected together by a chain of intermediate groups, we may at once infer their community of descent, and we put them all into the same class. As we find organs of high physiological importance--those which serve to preserve life under the most diverse conditions of existence--are generally the most constant, we attach especial value to them; but if these same organs, in another group or section of a group, are found to differ much, we at once value them less in our classification. We shall hereafter, I think, clearly see why embryological characters are of such high classificatory importance. Geographical distribution may sometimes be brought usefully into play in classing large and widely-distributed genera, because all the species of the same genus, inhabiting any distinct and isolated region, have in all probability descended from the same parents. We can understand, on these views, the very important distinction between real affinities and analogical or adaptive resemblances. Lamarck first called attention to this distinction, and he has been ably followed by Macleay and others. The resemblance, in the shape of the body and in the fin-like anterior limbs, between the dugong, which is a pachydermatous animal, and the whale, and between both these mammals and fishes, is analogical. Amongst insects there are innumerable {427} instances: thus Linnæus, misled by external appearances, actually classed an homopterous insect as a moth. We see something of the same kind even in our domestic varieties, as in the thickened stems of the common and swedish turnip. The resemblance of the greyhound and racehorse is hardly more fanciful than the analogies which have been drawn by some authors between very distinct animals. On my view of characters being of real importance for classification, only in so far as they reveal descent, we can clearly understand why analogical or adaptive character, although of the utmost importance to the welfare of the being, are almost valueless to the systematist. For animals, belonging to two most distinct lines of descent, may readily become adapted to similar conditions, and thus assume a close external resemblance; but such resemblances will not reveal--will rather tend to conceal their blood-relationship to their proper lines of descent. We can also understand the apparent paradox, that the very same characters are analogical when one class or order is compared with another, but give true affinities when the members of the same class or order are compared one with another: thus the shape of the body and fin-like limbs are only analogical when whales are compared with fishes, being adaptations in both classes for swimming through the water; but the shape of the body and fin-like limbs serve as characters exhibiting true affinity between the several members of the whale family; for these cetaceans agree in so many characters, great and small, that we cannot doubt that they have inherited their general shape of body and structure of limbs from a common ancestor. So it is with fishes. As members of distinct classes have often been adapted by successive slight modifications to live under nearly similar circumstances,--to inhabit for instance {428} the three elements of land, air, and water,--we can perhaps understand how it is that a numerical parallelism has sometimes been observed between the sub-groups in distinct classes. A naturalist, struck by a parallelism of this nature in any one class, by arbitrarily raising or sinking the value of the groups in other classes (and all our experience shows that this valuation has hitherto been arbitrary), could easily extend the parallelism over a wide range; and thus the septenary, quinary, quaternary, and ternary classifications have probably arisen. As the modified descendants of dominant species, belonging to the larger genera, tend to inherit the advantages, which made the groups to which they belong large and their parents dominant, they are almost sure to spread widely, and to seize on more and more places in the economy of nature. The larger and more dominant groups thus tend to go on increasing in size; and they consequently supplant many smaller and feebler groups. Thus we can account for the fact that all organisms, recent and extinct, are included under a few great orders, under still fewer classes, and all in one great natural system. As showing how few the higher groups are in number, and how widely spread they are throughout the world, the fact is striking, that the discovery of Australia has not added a single insect belonging to a new class; and that in the vegetable kingdom, as I learn from Dr. Hooker, it has added only two or three orders of small size. In the chapter on geological succession I attempted to show, on the principle of each group having generally diverged much in character during the long-continued process of modification, how it is that the more ancient forms of life often present characters in some slight degree intermediate between existing groups. A few {429} old and intermediate parent-forms having occasionally transmitted to the present day descendants but little modified, will give to us our so-called osculant or aberrant groups. The more aberrant any form is, the greater must be the number of connecting forms which on my theory have been exterminated and utterly lost. And we have some evidence of aberrant forms having suffered severely from extinction, for they are generally represented by extremely few species; and such species as do occur are generally very distinct from each other, which again implies extinction. The genera Ornithorhynchus and Lepidosiren, for example, would not have been less aberrant had each been represented by a dozen species instead of by a single one; but such richness in species, as I find after some investigation, does not commonly fall to the lot of aberrant genera. We can, I think, account for this fact only by looking at aberrant forms as failing groups conquered by more successful competitors, with a few members preserved by some unusual coincidence of favourable circumstances. Mr. Waterhouse has remarked that, when a member belonging to one group of animals exhibits an affinity to a quite distinct group, this affinity in most cases is general and not special: thus, according to Mr. Waterhouse, of all Rodents, the bizcacha is most nearly related to Marsupials; but in the points in which it approaches this order, its relations are general, and not to any one marsupial species more than to another. As the points of affinity of the bizcacha to Marsupials are believed to be real and not merely adaptive, they are due on my theory to inheritance in common. Therefore we must suppose either that all Rodents, including the bizcacha, branched off from some very ancient Marsupial, which will have had a character in some degree intermediate with respect to all existing Marsupials; or {430} that both Rodents and Marsupials branched off from a common progenitor, and that both groups have since undergone much modification in divergent directions. On either view we may suppose that the bizcacha has retained, by inheritance, more of the character of its ancient progenitor than have other Rodents; and therefore it will not be specially related to any one existing Marsupial, but indirectly to all or nearly all Marsupials, from having partially retained the character of their common progenitor, or of an early member of the group. On the other hand, of all Marsupials, as Mr. Waterhouse has remarked, the phascolomys resembles most nearly, not any one species, but the general order of Rodents. In this case, however, it may be strongly suspected that the resemblance is only analogical, owing to the phascolomys having become adapted to habits like those of a Rodent. The elder De Candolle has made nearly similar observations on the general nature of the affinities of distinct orders of plants. On the principle of the multiplication and gradual divergence in character of the species descended from a common parent, together with their retention by inheritance of some characters in common, we can understand the excessively complex and radiating affinities by which all the members of the same family or higher group are connected together. For the common parent of a whole family of species, now broken up by extinction into distinct groups and sub-groups, will have transmitted some of its characters, modified in various ways and degrees, to all; and the several species will consequently be related to each other by circuitous lines of affinity of various lengths (as may be seen in the diagram so often referred to), mounting up through many predecessors. As it is difficult to show the blood-relationship between the numerous kindred {431} of any ancient and noble family, even by the aid of a genealogical tree, and almost impossible to do this without this aid, we can understand the extraordinary difficulty which naturalists have experienced in describing, without the aid of a diagram, the various affinities which they perceive between the many living and extinct members of the same great natural class. Extinction, as we have seen in the fourth chapter, has played an important part in defining and widening the intervals between the several groups in each class. We may thus account even for the distinctness of whole classes from each other--for instance, of birds from all other vertebrate animals--by the belief that many ancient forms of life have been utterly lost, through which the early progenitors of birds were formerly connected with the early progenitors of the other vertebrate classes. There has been less entire extinction of the forms of life which once connected fishes with batrachians. There has been still less in some other classes, as in that of the Crustacea, for here the most wonderfully diverse forms are still tied together by a long, but broken, chain of affinities. Extinction has only separated groups: it has by no means made them; for if every form which has ever lived on this earth were suddenly to reappear, though it would be quite impossible to give definitions by which each group could be distinguished from other groups, as all would blend together by steps as fine as those between the finest existing varieties, nevertheless a natural classification, or at least a natural arrangement, would be possible. We shall see this by turning to the diagram: the letters, A to L, may represent eleven Silurian genera, some of which have produced large groups of modified descendants. Every intermediate link between these eleven genera and their primordial parent, and every {432} intermediate link in each branch and sub-branch of their descendants, may be supposed to be still alive; and the links to be as fine as those between the finest varieties. In this case it would be quite impossible to give any definition by which the several members of the several groups could be distinguished from their more immediate parents; or these parents from their ancient and unknown progenitor. Yet the natural arrangement in the diagram would still hold good; and, on the principle of inheritance, all the forms descended from A, or from I, would have something in common. In a tree we can specify this or that branch, though at the actual fork the two unite and blend together. We could not, as I have said, define the several groups; but we could pick out types, or forms, representing most of the characters of each group, whether large or small, and thus give a general idea of the value of the differences between them. This is what we should be driven to, if we were ever to succeed in collecting all the forms in any class which have lived throughout all time and space. We shall certainly never succeed in making so perfect a collection: nevertheless, in certain classes, we are tending in this direction; and Milne Edwards has lately insisted, in an able paper, on the high importance of looking to types, whether or not we can separate and define the groups to which such types belong. Finally, we have seen that natural selection, which results from the struggle for existence, and which almost inevitably induces extinction and divergence of character in the many descendants from one dominant parent-species, explains that great and universal feature in the affinities of all organic beings, namely, their subordination in group under group. We use the element of descent in classing the individuals of both sexes and of all ages, although having few characters in common, {433} under one species; we use descent in classing acknowledged varieties, however different they may be from their parent; and I believe this element of descent is the hidden bond of connexion which naturalists have sought under the term of the Natural System. On this idea of the natural system being, in so far as it has been perfected, genealogical in its arrangement, with the grades of difference between the descendants from a common parent, expressed by the terms genera, families, orders, &c., we can understand the rules which we are compelled to follow in our classification. We can understand why we value certain resemblances far more than others; why we are permitted to use rudimentary and useless organs, or others of trifling physiological importance; why, in comparing one group with a distinct group, we summarily reject analogical or adaptive characters, and yet use these same characters within the limits of the same group. We can clearly see how it is that all living and extinct forms can be grouped together in one great system; and how the several members of each class are connected together by the most complex and radiating lines of affinities. We shall never, probably, disentangle the inextricable web of affinities between the members of any one class; but when we have a distinct object in view, and do not look to some unknown plan of creation, we may hope to make sure but slow progress. _Morphology._--We have seen that the members of the same class, independently of their habits of life, resemble each other in the general plan of their organisation. This resemblance is often expressed by the term "unity of type;" or by saying that the several parts and organs in the different species of the class are homologous. The whole subject is included under {434} the general name of Morphology. This is the most interesting department of natural history, and may be said to be its very soul. What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include similar bones, in the same relative positions? Geoffroy St. Hilaire has insisted strongly on the high importance of relative connexion in homologous organs: the parts may change to almost any extent in form and size, and yet they always remain connected together in the same order. We never find, for instance, the bones of the arm and forearm, or of the thigh and leg, transposed. Hence the same names can be given to the homologous bones in widely different animals. We see the same great law in the construction of the mouths of insects: what can be more different than the immensely long spiral proboscis of a sphinx-moth, the curious folded one of a bee or bug, and the great jaws of a beetle?--yet all these organs, serving for such different purposes, are formed by infinitely numerous modifications of an upper lip, mandibles, and two pairs of maxillæ. Analogous laws govern the construction of the mouths and limbs of crustaceans. So it is with the flowers of plants. Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or by the doctrine of final causes. The hopelessness of the attempt has been expressly admitted by Owen in his most interesting work on the 'Nature of Limbs.' On the ordinary view of the independent creation of each being, we can only say that so it is;--that it has so pleased the Creator to construct each animal and plant. The explanation is manifest on the theory of the {435} natural selection of successive slight modifications,--each modification being profitable in some way to the modified form, but often affecting by correlation of growth other parts of the organisation. In changes of this nature, there will be little or no tendency to modify the original pattern, or to transpose parts. The bones of a limb might be shortened and widened to any extent, and become gradually enveloped in thick membrane, so as to serve as a fin; or a webbed foot might have all its bones, or certain bones, lengthened to any extent, and the membrane connecting them increased to any extent, so as to serve as a wing: yet in all this great amount of modification there will be no tendency to alter the framework of bones or the relative connexion of the several parts. If we suppose that the ancient progenitor, the archetype as it may be called, of all mammals, had its limbs constructed on the existing general pattern, for whatever purpose they served, we can at once perceive the plain signification of the homologous construction of the limbs throughout the whole class. So with the mouths of insects, we have only to suppose that their common progenitor had an upper lip, mandibles, and two pair of maxillæ, these parts being perhaps very simple in form; and then natural selection, acting on some originally created form, will account for the infinite diversity in structure and function of the mouths of insects. Nevertheless, it is conceivable that the general pattern of an organ might become so much obscured as to be finally lost, by the atrophy and ultimately by the complete abortion of certain parts, by the soldering together of other parts, and by the doubling or multiplication of others,--variations which we know to be within the limits of possibility. In the paddles of the extinct gigantic sea-lizards, and in the mouths of certain suctorial crustaceans, the {436} general pattern seems to have been thus to a certain extent obscured. There is another and equally curious branch of the present subject; namely, the comparison not of the same part in different members of a class, but of the different parts or organs in the same individual. Most physiologists believe that the bones of the skull are homologous with--that is correspond in number and in relative connexion with--the elemental parts of a certain number of vertebræ. The anterior and posterior limbs in each member of the vertebrate and articulate classes are plainly homologous. We see the same law in comparing the wonderfully complex jaws and legs in crustaceans. It is familiar to almost every one, that in a flower the relative position of the sepals, petals, stamens, and pistils, as well as their intimate structure, are intelligible on the view that they consist of metamorphosed leaves, arranged in a spire. In monstrous plants, we often get direct evidence of the possibility of one organ being transformed into another; and we can actually see in embryonic crustaceans and in many other animals, and in flowers, that organs, which when mature become extremely different, are at an early stage of growth exactly alike. How inexplicable are these facts on the ordinary view of creation! Why should the brain be enclosed in a box composed of such numerous and such extraordinary shaped pieces of bone? As Owen has remarked, the benefit derived from the yielding of the separate pieces in the act of parturition of mammals, will by no means explain the same construction in the skulls of birds. Why should similar bones have been created in the formation of the wing and leg of a bat, used as they are for such totally different purposes? Why should one crustacean, which has an extremely complex {437} mouth formed of many parts, consequently always have fewer legs; or conversely, those with many legs have simpler mouths? Why should the sepals, petals, stamens, and pistils in any individual flower, though fitted for such widely different purposes, be all constructed on the same pattern? On the theory of natural selection, we can satisfactorily answer these questions. In the vertebrata, we see a series of internal vertebræ bearing certain processes and appendages; in the articulata, we see the body divided into a series of segments, bearing external appendages; and in flowering plants, we see a series of successive spiral whorls of leaves. An indefinite repetition of the same part or organ is the common characteristic (as Owen has observed) of all low or little-modified forms; therefore we may readily believe that the unknown progenitor of the vertebrata possessed many vertebræ; the unknown progenitor of the articulata, many segments; and the unknown progenitor of flowering plants, many spiral whorls of leaves. We have formerly seen that parts many times repeated are eminently liable to vary in number and structure; consequently it is quite probable that natural selection, during a long-continued course of modification, should have seized on a certain number of the primordially similar elements, many times repeated, and have adapted them to the most diverse purposes. And as the whole amount of modification will have been effected by slight successive steps, we need not wonder at discovering in such parts or organs, a certain degree of fundamental resemblance, retained by the strong principle of inheritance. In the great class of molluscs, though we can homologise the parts of one species with those of other and distinct species, we can indicate but few serial homologies; that is, we are seldom enabled to say that one {438} part or organ is homologous with another in the same individual. And we can understand this fact; for in molluscs, even in the lowest members of the class, we do not find nearly so much indefinite repetition of any one part, as we find in the other great classes of the animal and vegetable kingdoms. Naturalists frequently speak of the skull as formed of metamorphosed vertebræ: the jaws of crabs as metamorphosed legs; the stamens and pistils of flowers as metamorphosed leaves; but it would in these cases probably be more correct, as Professor Huxley has remarked, to speak of both skull and vertebræ, both jaws and legs, &c.,--as having been metamorphosed, not one from the other, but from some common element. Naturalists, however, use such language only in a metaphorical sense: they are far from meaning that during a long course of descent, primordial organs of any kind--vertebræ in the one case and legs in the other--have actually been modified into skulls or jaws. Yet so strong is the appearance of a modification of this nature having occurred, that naturalists can hardly avoid employing language having this plain signification. On my view these terms may be used literally; and the wonderful fact of the jaws, for instance, of a crab retaining numerous characters, which they would probably have retained through inheritance, if they had really been metamorphosed during a long course of descent from true legs, or from some simple appendage, is explained. _Embryology._--It has already been casually remarked that certain organs in the individual, which when mature become widely different and serve for different purposes, are in the embryo exactly alike. The embryos, also, of distinct animals within the same class are often strikingly similar: a better proof of this cannot be given, than a {439} circumstance mentioned by Agassiz, namely, that having forgotten to ticket the embryo of some vertebrate animal, he cannot now tell whether it be that of a mammal, bird, or reptile. The vermiform larvæ of moths, flies, beetles, &c., resemble each other much more closely than do the mature insects; but in the case of larvæ, the embryos are active, and have been adapted for special lines of life. A trace of the law of embryonic resemblance, sometimes lasts till a rather late age: thus birds of the same genus, and of closely allied genera, often resemble each other in their first and second plumage; as we see in the spotted feathers in the thrush group. In the cat tribe, most of the species are striped or spotted in lines; and stripes can be plainly distinguished in the whelp of the lion. We occasionally though rarely see something of this kind in plants: thus the embryonic leaves of the ulex or furze, and the first leaves of the phyllodineous acaceas, are pinnate or divided like the ordinary leaves of the leguminosæ. The points of structure, in which the embryos of widely different animals of the same class resemble each other, often have no direct relation to their conditions of existence. We cannot, for instance, suppose that in the embryos of the vertebrata the peculiar loop-like course of the arteries near the branchial slits are related to similar conditions,--in the young mammal which is nourished in the womb of its mother, in the egg of the bird which is hatched in a nest, and in the spawn of a frog under water. We have no more reason to believe in such a relation, than we have to believe that the same bones in the hand of a man, wing of a bat, and fin of a porpoise, are related to similar conditions of life. No one will suppose that the stripes on the whelp of a lion, or the spots on the young blackbird, {440} are of any use to these animals, or are related to the conditions to which they are exposed. The case, however, is different when an animal during any part of its embryonic career is active, and has to provide for itself. The period of activity may come on earlier or later in life; but whenever it comes on, the adaptation of the larva to its conditions of life is just as perfect and as beautiful as in the adult animal. From such special adaptations, the similarity of the larvæ or active embryos of allied animals is sometimes much obscured; and cases could be given of the larvæ of two species, or of two groups of species, differing quite as much, or even more, from each other than do their adult parents. In most cases, however, the larvæ, though active, still obey, more or less closely, the law of common embryonic resemblance. Cirripedes afford a good instance of this: even the illustrious Cuvier did not perceive that a barnacle was, as it certainly is, a crustacean; but a glance at the larva shows this to be the case in an unmistakeable manner. So again the two main divisions of cirripedes, the pedunculated and sessile, which differ widely in external appearance, have larvæ in all their stages barely distinguishable. The embryo in the course of development generally rises in organisation: I use this expression, though I am aware that it is hardly possible to define clearly what is meant by the organisation being higher or lower. But no one probably will dispute that the butterfly is higher than the caterpillar. In some cases, however, the mature animal is generally considered as lower in the scale than the larva, as with certain parasitic crustaceans. To refer once again to cirripedes: the larvæ in the first stage have three pairs of legs, a very simple single eye, and a probosciformed mouth, with which they feed largely, for they increase much in {441} size. In the second stage, answering to the chrysalis stage of butterflies, they have six pairs of beautifully constructed natatory legs, a pair of magnificent compound eyes, and extremely complex antennæ; but they have a closed and imperfect mouth, and cannot feed: their function at this stage is, to search by their well-developed organs of sense, and to reach by their active powers of swimming, a proper place on which to become attached and to undergo their final metamorphosis. When this is completed they are fixed for life: their legs are now converted into prehensile organs; they again obtain a well-constructed mouth; but they have no antennæ, and their two eyes are now reconverted into a minute, single, and very simple eye-spot. In this last and complete state, cirripedes may be considered as either more highly or more lowly organised than they were in the larval condition. But in some genera the larvæ become developed either into hermaphrodites having the ordinary structure, or into what I have called complemental males: and in the latter, the development has assuredly been retrograde; for the male is a mere sack, which lives for a short time, and is destitute of mouth, stomach, or other organ of importance, excepting for reproduction. We are so much accustomed to see differences in structure between the embryo and the adult, and likewise a close similarity in the embryos of widely different animals within the same class, that we might be led to look at these facts as necessarily contingent in some manner on growth. But there is no obvious reason why, for instance, the wing of a bat, or the fin of a porpoise, should not have been sketched out with all the parts in proper proportion, as soon as any structure became visible in the embryo. And in some whole groups of animals and in certain members of other groups, the embryo does not at any period differ widely from the {442} adult: thus Owen has remarked in regard to cuttle-fish, "there is no metamorphosis; the cephalopodic character is manifested long before the parts of the embryo are completed;" and again in spiders, "there is nothing worthy to be called a metamorphosis." The larvæ of insects, whether adapted to the most diverse and active habits, or quite inactive, being fed by their parents or placed in the midst of proper nutriment, yet nearly all pass through a similar worm-like stage of development; but in some few cases, as in that of Aphis, if we look to the admirable drawings by Professor Huxley of the development of this insect, we see no trace of the vermiform stage. How, then, can we explain these several facts in embryology,--namely the very general, but not universal difference in structure between the embryo and the adult;--of parts in the same individual embryo, which ultimately become very unlike and serve for diverse purposes, being at this early period of growth alike;--of embryos of different species within the same class, generally, but not universally, resembling each other;--of the structure of the embryo not being closely related to its conditions of existence, except when the embryo becomes at any period of life active and has to provide for itself;--of the embryo apparently having sometimes a higher organisation than the mature animal, into which it is developed? I believe that all these facts can be explained, as follows, on the view of descent with modification. It is commonly assumed, perhaps from monstrosities often affecting the embryos at a very early period, that slight variations necessarily appear at an equally early period. But we have little evidence on this head--indeed the evidence rather points the other way; for it is notorious that breeders of cattle, horses, and various {443} fancy animals, cannot positively tell, until some time after the animal has been born, what its merits or form will ultimately turn out. We see this plainly in our own children; we cannot always tell whether the child will be tall or short, or what its precise features will be. The question is not, at what period of life any variation has been caused, but at what period it is fully displayed. The cause may have acted, and I believe generally has acted, even before the embryo is formed; and the variation may be due to the male and female sexual elements having been affected by the conditions to which either parent, or their ancestors, have been exposed. Nevertheless an effect thus caused at a very early period, even before the formation of the embryo, may appear late in life; as when an hereditary disease, which appears in old age alone, has been communicated to the offspring from the reproductive element of one parent. Or again, as when the horns of cross-bred cattle have been affected by the shape of the horns of either parent. For the welfare of a very young animal, as long as it remains in its mother's womb, or in the egg, or as long as it is nourished and protected by its parent, it must be quite unimportant whether most of its characters are fully acquired a little earlier or later in life. It would not signify, for instance, to a bird which obtained its food best by having a long beak, whether or not it assumed a beak of this particular length, as long as it was fed by its parents. Hence, I conclude, that it is quite possible, that each of the many successive modifications, by which each species has acquired its present structure, may have supervened at a not very early period of life; and some direct evidence from our domestic animals supports this view. But in other cases it is quite possible that each successive modification, or {444} most of them, may have appeared at an extremely early period. I have stated in the first chapter, that there is some evidence to render it probable, that at whatever age any variation first appears in the parent, it tends to reappear at a corresponding age in the offspring. Certain variations can only appear at corresponding ages, for instance, peculiarities in the caterpillar, cocoon, or imago states of the silk-moth; or, again, in the horns of almost full-grown cattle. But further than this, variations which, for all that we can see, might have appeared earlier or later in life, tend to appear at a corresponding age in the offspring and parent. I am far from meaning that this is invariably the case; and I could give a good many cases of variations (taking the word in the largest sense) which have supervened at an earlier age in the child than in the parent. These two principles, if their truth be admitted, will, I believe, explain all the above specified leading facts in embryology. But first let us look at a few analogous cases in domestic varieties. Some authors who have written on Dogs, maintain that the greyhound and bulldog, though appearing so different, are really varieties most closely allied, and have probably descended from the same wild stock; hence I was curious to see how far their puppies differed from each other: I was told by breeders that they differed just as much as their parents, and this, judging by the eye, seemed almost to be the case; but on actually measuring the old dogs and their six-days old puppies, I found that the puppies had not nearly acquired their full amount of proportional difference. So, again, I was told that the foals of cart and race-horses differed as much as the full-grown animals; and this surprised me greatly, as I think it probable that the difference between these two breeds has been wholly {445} caused by selection under domestication; but having had careful measurements made of the dam and of a three-days old colt of a race and heavy cart-horse, I find that the colts have by no means acquired their full amount of proportional difference. As the evidence appears to me conclusive, that the several domestic breeds of Pigeon have descended from one wild species, I compared young pigeons of various breeds, within twelve hours after being hatched; I carefully measured the proportions (but will not here give details) of the beak, width of mouth, length of nostril and of eyelid, size of feet and length of leg, in the wild stock, in pouters, fantails, runts, barbs, dragons, carriers, and tumblers. Now some of these birds, when mature, differ so extraordinarily in length and form of beak, that they would, I cannot doubt, be ranked in distinct genera, had they been natural productions. But when the nestling birds of these several breeds were placed in a row, though most of them could be distinguished from each other, yet their proportional differences in the above specified several points were incomparably less than in the full-grown birds. Some characteristic points of difference--for instance, that of the width of mouth--could hardly be detected in the young. But there was one remarkable exception to this rule, for the young of the short-faced tumbler differed from the young of the wild rock-pigeon and of the other breeds, in all its proportions, almost exactly as much as in the adult state. The two principles above given seem to me to explain these facts in regard to the later embryonic stages of our domestic varieties. Fanciers select their horses, dogs, and pigeons, for breeding, when they are nearly grown up: they are indifferent whether the desired qualities and structures have been acquired earlier or {446} later in life, if the full-grown animal possesses them. And the cases just given, more especially that of pigeons, seem to show that the characteristic differences which give value to each breed, and which have been accumulated by man's selection, have not generally first appeared at an early period of life, and have been inherited by the offspring at a corresponding not early period. But the case of the short-faced tumbler, which when twelve hours old had acquired its proper proportions, proves that this is not the universal rule; for here the characteristic differences must either have appeared at an earlier period than usual, or, if not so, the differences must have been inherited, not at the corresponding, but at an earlier age. Now let us apply these facts and the above two principles--which latter, though not proved true, can be shown to be in some degree probable--to species in a state of nature. Let us take a genus of birds, descended on my theory from some one parent-species, and of which the several new species have become modified through natural selection in accordance with their diverse habits. Then, from the many slight successive steps of variation having supervened at a rather late age, and having been inherited at a corresponding age, the young of the new species of our supposed genus will manifestly tend to resemble each other much more closely than do the adults, just as we have seen in the case of pigeons. We may extend this view to whole families or even classes. The fore-limbs, for instance, which served as legs in the parent-species, may have become, by a long course of modification, adapted in one descendant to act as hands, in another as paddles, in another as wings; and on the above two principles--namely of each successive modification supervening at a rather late age, and being inherited at a {447} corresponding late age--the fore-limbs in the embryos of the several descendants of the parent-species will still resemble each other closely, for they will not have been modified. But in each of our new species, the embryonic fore-limbs will differ greatly from the fore-limbs in the mature animal; the limbs in the latter having undergone much modification at a rather late period of life, and having thus been converted into hands, or paddles, or wings. Whatever influence long-continued exercise or use on the one hand, and disuse on the other, may have in modifying an organ, such influence will mainly affect the mature animal, which has come to its full powers of activity and has to gain its own living; and the effects thus produced will be inherited at a corresponding mature age. Whereas the young will remain unmodified, or be modified in a lesser degree, by the effects of use and disuse. In certain cases the successive steps of variation might supervene, from causes of which we are wholly ignorant, at a very early period of life, or each step might be inherited at an earlier period than that at which it first appeared. In either case (as with the short-faced tumbler) the young or embryo would closely resemble the mature parent-form. We have seen that this is the rule of development in certain whole groups of animals, as with cuttle-fish and spiders, and with a few members of the great class of insects, as with Aphis. With respect to the final cause of the young in these cases not undergoing any metamorphosis, or closely resembling their parents from their earliest age, we can see that this would result from the two following contingencies: firstly, from the young, during a course of modification carried on for many generations, having to provide for their own wants at a very early stage {448} of development, and secondly, from their following exactly the same habits of life with their parents; for in this case, it would be indispensable for the existence of the species, that the child should be modified at a very early age in the same manner with its parents, in accordance with their similar habits. Some further explanation, however, of the embryo not undergoing any metamorphosis is perhaps requisite. If, on the other hand, it profited the young to follow habits of life in any degree different from those of their parent, and consequently to be constructed in a slightly different manner, then, on the principle of inheritance at corresponding ages, the active young or larvæ might easily be rendered by natural selection different to any conceivable extent from their parents. Such differences might, also, become correlated with successive stages of development; so that the larvæ, in the first stage, might differ greatly from the larvæ in the second stage, as we have seen to be the case with cirripedes. The adult might become fitted for sites or habits, in which organs of locomotion or of the senses, &c., would be useless; and in this case the final metamorphosis would be said to be retrograde. As all the organic beings, extinct and recent, which have ever lived on this earth have to be classed together, and as all have been connected by the finest gradations, the best, or indeed, if our collections were nearly perfect, the only possible arrangement, would be genealogical. Descent being on my view the hidden bond of connexion which naturalists have been seeking under the term of the natural system. On this view we can understand how it is that, in the eyes of most naturalists, the structure of the embryo is even more important for classification than that of the adult. For the embryo is the animal in its less modified state; {449} and in so far it reveals the structure of its progenitor. In two groups of animals, however much they may at present differ from each other in structure and habits, if they pass through the same or similar embryonic stages, we may feel assured that they have both descended from the same or nearly similar parents, and are therefore in that degree closely related. Thus, community in embryonic structure reveals community of descent. It will reveal this community of descent, however much the structure of the adult may have been modified and obscured; we have seen, for instance, that cirripedes can at once be recognised by their larvæ as belonging to the great class of crustaceans. As the embryonic state of each species and group of species partially shows us the structure of their less modified ancient progenitors, we can clearly see why ancient and extinct forms of life should resemble the embryos of their descendants,--our existing species. Agassiz believes this to be a law of nature; but I am bound to confess that I only hope to see the law hereafter proved true. It can be proved true in those cases alone in which the ancient state, now supposed to be represented in existing embryos, has not been obliterated, either by the successive variations in a long course of modification having supervened at a very early age, or by the variations having been inherited at an earlier period than that at which they first appeared. It should also be borne in mind, that the supposed law of resemblance of ancient forms of life to the embryonic stages of recent forms, may be true, but yet, owing to the geological record not extending far enough back in time, may remain for a long period, or for ever, incapable of demonstration. Thus, as it seems to me, the leading facts in embryology, which are second in importance to none in natural history, are explained on the principle of slight {450} modifications not appearing, in the many descendants from some one ancient progenitor, at a very early period in the life of each, though perhaps caused at the earliest, and being inherited at a corresponding not early period. Embryology rises greatly in interest, when we thus look at the embryo as a picture, more or less obscured, of the common parent-form of each great class of animals. _Rudimentary, atrophied, or aborted Organs._--Organs or parts in this strange condition, bearing the stamp of inutility, are extremely common throughout nature. For instance, rudimentary mammæ are very general in the males of mammals: I presume that the "bastard-wing" in birds may be safely considered as a digit in a rudimentary state: in very many snakes one lobe of the lungs is rudimentary; in other snakes there are rudiments of the pelvis and hind limbs. Some of the cases of rudimentary organs are extremely curious; for instance, the presence of teeth in foetal whales, which when grown up have not a tooth in their heads; and the presence of teeth, which never cut through the gums, in the upper jaws of our unborn calves. It has even been stated on good authority that rudiments of teeth can be detected in the beaks of certain embryonic birds. Nothing can be plainer than that wings are formed for flight, yet in how many insects do we see wings so reduced in size as to be utterly incapable of flight, and not rarely lying under wing-cases, firmly soldered together! The meaning of rudimentary organs is often quite unmistakeable: for instance there are beetles of the same genus (and even of the same species) resembling each other most closely in all respects, one of which will have full-sized wings, and another mere rudiments of membrane; and here it is impossible to doubt, that the {451} rudiments represent wings. Rudimentary organs sometimes retain their potentiality, and are merely not developed: this seems to be the case with the mammæ of male mammals, for many instances are on record of these organs having become well developed in full-grown males, and having secreted milk. So again there are normally four developed and two rudimentary teats in the udders of the genus Bos, but in our domestic cows the two sometimes become developed and give milk. In plants of the same species the petals sometimes occur as mere rudiments, and sometimes in a well-developed state. In plants with separated sexes, the male flowers often have a rudiment of a pistil; and Kölreuter found that by crossing such male plants with an hermaphrodite species, the rudiment of the pistil in the hybrid offspring was much increased in size; and this shows that the rudiment and the perfect pistil are essentially alike in nature. An organ serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose; and remain perfectly efficient for the other. Thus in plants, the office of the pistil is to allow the pollen-tubes to reach the ovules protected in the ovarium at its base. The pistil consists of a stigma supported on the style; but in some Compositæ, the male florets, which of course cannot be fecundated, have a pistil, which is in a rudimentary state, for it is not crowned with a stigma; but the style remains well developed, and is clothed with hairs as in other compositæ, for the purpose of brushing the pollen out of the surrounding anthers. Again, an organ may become rudimentary for its proper purpose, and be used for a distinct object: in certain fish the swim-bladder seems to be nearly rudimentary for its proper function of giving buoyancy, but has become converted into a {452} nascent breathing organ or lung. Other similar instances could be given. Organs, however little developed, if of use, should not be called rudimentary; they cannot properly be said to be in an atrophied condition; they may be called nascent, and may hereafter be developed to any extent by natural selection. Rudimentary organs, on the other hand, are essentially useless, as teeth which never cut through the gums; in a still less developed condition, they would be of still less use. They cannot, therefore, under their present condition, have been formed by natural selection, which acts solely by the preservation of useful modifications; they have been retained, as we shall see, by inheritance, and relate to a former condition of their possessor. It is difficult to know what are nascent organs; looking to the future, we cannot of course tell how any part will be developed, and whether it is now nascent; looking to the past, creatures with an organ in a nascent condition will generally have been supplanted and exterminated by their successors with the organ in a more perfect and developed condition. The wing of the penguin is of high service, and acts as a fin; it may, therefore, represent the nascent state of the wings of birds; not that I believe this to be the case, it is more probably a reduced organ, modified for a new function: the wing of the Apteryx is useless, and is truly rudimentary. The mammary glands of the Ornithorhynchus may, perhaps, be considered, in comparison with the udder of a cow, as in a nascent state. The ovigerous frena of certain cirripedes, which are only slightly developed and which have ceased to give attachment to the ova, are nascent branchiæ. Rudimentary organs in the individuals of the same species are very liable to vary in degree of development {453} and in other respects. Moreover, in closely allied species, the degree to which the same organ has been rendered rudimentary occasionally differs much. This latter fact is well exemplified in the state of the wings of the female moths in certain groups. Rudimentary organs may be utterly aborted; and this implies, that we find in an animal or plant no trace of an organ, which analogy would lead us to expect to find, and which is occasionally found in monstrous individuals of the species. Thus in the snapdragon (antirrhinum) we generally do not find a rudiment of a fifth stamen; but this may sometimes be seen. In tracing the homologies of the same part in different members of a class, nothing is more common, or more necessary, than the use and discovery of rudiments. This is well shown in the drawings given by Owen of the bones of the leg of the horse, ox, and rhinoceros. It is an important fact that rudimentary organs, such as teeth in the upper jaws of whales and ruminants, can often be detected in the embryo, but afterwards wholly disappear. It is also, I believe, a universal rule, that a rudimentary part or organ is of greater size relatively to the adjoining parts in the embryo, than in the adult; so that the organ at this early age is less rudimentary, or even cannot be said to be in any degree rudimentary. Hence, also, a rudimentary organ in the adult is often said to have retained its embryonic condition. I have now given the leading facts with respect to rudimentary organs. In reflecting on them, every one must be struck with astonishment: for the same reasoning power which tells us plainly that most parts and organs are exquisitely adapted for certain purposes, tells us with equal plainness that these rudimentary or atrophied organs, are imperfect and useless. In works {454} on natural history rudimentary organs are generally said to have been created "for the sake of symmetry," or in order "to complete the scheme of nature;" but this seems to me no explanation, merely a re-statement of the fact. Would it be thought sufficient to say that because planets revolve in elliptic courses round the sun, satellites follow the same course round the planets, for the sake of symmetry, and to complete the scheme of nature? An eminent physiologist accounts for the presence of rudimentary organs, by supposing that they serve to excrete matter in excess, or injurious to the system; but can we suppose that the minute papilla, which often represents the pistil in male flowers, and which is formed merely of cellular tissue, can thus act? Can we suppose that the formation of rudimentary teeth, which are subsequently absorbed, can be of any service to the rapidly growing embryonic calf by the excretion of precious phosphate of lime? When a man's fingers have been amputated, imperfect nails sometimes appear on the stumps: I could as soon believe that these vestiges of nails have appeared, not from unknown laws of growth, but in order to excrete horny matter, as that the rudimentary nails on the fin of the manatee were formed for this purpose. On my view of descent with modification, the origin of rudimentary organs is simple. We have plenty of cases of rudimentary organs in our domestic productions,--as the stump of a tail in tailless breeds,--the vestige of an ear in earless breeds,--the reappearance of minute dangling horns in hornless breeds of cattle, more especially, according to Youatt, in young animals,--and the state of the whole flower in the cauliflower. We often see rudiments of various parts in monsters. But I doubt whether any of these cases throw light on the origin of rudimentary organs in a state of nature, {455} further than by showing that rudiments can be produced; for I doubt whether species under nature ever undergo abrupt changes. I believe that disuse has been the main agency; that it has led in successive generations to the gradual reduction of various organs, until they have become rudimentary,--as in the case of the eyes of animals inhabiting dark caverns, and of the wings of birds inhabiting oceanic islands, which have seldom been forced to take flight, and have ultimately lost the power of flying. Again, an organ useful under certain conditions, might become injurious under others, as with the wings of beetles living on small and exposed islands; and in this case natural selection would continue slowly to reduce the organ, until it was rendered harmless and rudimentary. Any change in function, which can be effected by insensibly small steps, is within the power of natural selection; so that an organ rendered, during changed habits of life, useless or injurious for one purpose, might be modified and used for another purpose. Or an organ might be retained for one alone of its former functions. An organ, when rendered useless, may well be variable, for its variations cannot be checked by natural selection. At whatever period of life disuse or selection reduces an organ, and this will generally be when the being has come to maturity and to its full powers of action, the principle of inheritance at corresponding ages will reproduce the organ in its reduced state at the same age, and consequently will seldom affect or reduce it in the embryo. Thus we can understand the greater relative size of rudimentary organs in the embryo, and their lesser relative size in the adult. But if each step of the process of reduction were to be inherited, not at the corresponding age, but at an extremely early period of life (as we have good {456} reason to believe to be possible), the rudimentary part would tend to be wholly lost, and we should have a case of complete abortion. The principle, also, of economy, explained in a former chapter, by which the materials forming any part or structure, if not useful to the possessor, will be saved as far as is possible, will probably often come into play; and this will tend to cause the entire obliteration of a rudimentary organ. As the presence of rudimentary organs is thus due to the tendency in every part of the organisation, which has long existed, to be inherited--we can understand, on the genealogical view of classification, how it is that systematists have found rudimentary parts as useful as, or even sometimes more useful than, parts of high physiological importance. Rudimentary organs may be compared with the letters in a word, still retained in the spelling, but become useless in the pronunciation, but which serve as a clue in seeking for its derivation. On the view of descent with modification, we may conclude that the existence of organs in a rudimentary, imperfect, and useless condition, or quite aborted, far from presenting a strange difficulty, as they assuredly do on the ordinary doctrine of creation, might even have been anticipated, and can be accounted for by the laws of inheritance. _Summary._--In this chapter I have attempted to show, that the subordination of group to group in all organisms throughout all time; that the nature of the relationship, by which all living and extinct beings are united by complex, radiating, and circuitous lines of affinities into one grand system; the rules followed and the difficulties encountered by naturalists in their classifications; the value set upon characters, if constant and prevalent, whether of high vital importance, or of the most trifling {457} importance, or, as in rudimentary organs, of no importance; the wide opposition in value between analogical or adaptive characters, and characters of true affinity; and other such rules;--all naturally follow on the view of the common parentage of those forms which are considered by naturalists as allied, together with their modification through natural selection, with its contingencies of extinction and divergence of character. In considering this view of classification, it should be borne in mind that the element of descent has been universally used in ranking together the sexes, ages, and acknowledged varieties of the same species, however different they may be in structure. If we extend the use of this element of descent,--the only certainly known cause of similarity in organic beings,--we shall understand what is meant by the natural system: it is genealogical in its attempted arrangement, with the grades of acquired difference marked by the terms varieties, species, genera, families, orders, and classes. On this same view of descent with modification, all the great facts in Morphology become intelligible,--whether we look to the same pattern displayed in the homologous organs, to whatever purpose applied, of the different species of a class; or to the homologous parts constructed on the same pattern in each individual animal and plant. On the principle of successive slight variations, not necessarily or generally supervening at a very early period of life, and being inherited at a corresponding period, we can understand the great leading facts in Embryology; namely, the resemblance in an individual embryo of the homologous parts, which when matured will become widely different from each other in structure and function; and the resemblance in different species of a class of the homologous parts or {458} organs, though fitted in the adult members for purposes as different as possible. Larvæ are active embryos, which have become specially modified in relation to their habits of life, through the principle of modifications being inherited at corresponding ages. On this same principle--and bearing in mind, that when organs are reduced in size, either from disuse or selection, it will generally be at that period of life when the being has to provide for its own wants, and bearing in mind how strong is the principle of inheritance--the occurrence of rudimentary organs and their final abortion, present to us no inexplicable difficulties; on the contrary, their presence might have been even anticipated. The importance of embryological characters and of rudimentary organs in classification is intelligible, on the view that an arrangement is only so far natural as it is genealogical. Finally, the several classes of facts which have been considered in this chapter, seem to me to proclaim so plainly, that the innumerable species, genera, and families of organic beings, with which this world is peopled, have all descended, each within its own class or group, from common parents, and have all been modified in the course of descent, that I should without hesitation adopt this view, even if it were unsupported by other facts or arguments. * * * * * {459} CHAPTER XIV. RECAPITULATION AND CONCLUSION. Recapitulation of the difficulties on the theory of Natural Selection--Recapitulation of the general and special circumstances in its favour--Causes of the general belief in the immutability of species--How far the theory of natural selection may be extended--Effects of its adoption on the study of Natural history--Concluding remarks. As this whole volume is one long argument, it may be convenient to the reader to have the leading facts and inferences briefly recapitulated. That many and serious objections may be advanced against the theory of descent with modification through natural selection, I do not deny. I have endeavoured to give to them their full force. Nothing at first can appear more difficult to believe than that the more complex organs and instincts should have been perfected, not by means superior to, though analogous with, human reason, but by the accumulation of innumerable slight variations, each good for the individual possessor. Nevertheless, this difficulty, though appearing to our imagination insuperably great, cannot be considered real if we admit the following propositions, namely,--that gradations in the perfection of any organ or instinct which we may consider, either do now exist or could have existed, each good of its kind,--that all organs and instincts are, in ever so slight a degree, variable,--and, lastly, that there is a struggle for existence leading to the preservation of each profitable deviation of structure or instinct. The truth of these propositions cannot, I think, be disputed. {460} It is, no doubt, extremely difficult even to conjecture by what gradations many structures have been perfected, more especially amongst broken and failing groups of organic beings; but we see so many strange gradations in nature, that we ought to be extremely cautious in saying that any organ or instinct, or any whole being, could not have arrived at its present state by many graduated steps. There are, it must be admitted, cases of special difficulty on the theory of natural selection; and one of the most curious of these is the existence of two or three defined castes of workers or sterile females in the same community of ants; but I have attempted to show how this difficulty can be mastered. With respect to the almost universal sterility of species when first crossed, which forms so remarkable a contrast with the almost universal fertility of varieties when crossed, I must refer the reader to the recapitulation of the facts given at the end of the eighth chapter, which seem to me conclusively to show that this sterility is no more a special endowment than is the incapacity of two trees to be grafted together; but that it is incidental on constitutional differences in the reproductive systems of the intercrossed species. We see the truth of this conclusion in the vast difference in the result, when the same two species are crossed reciprocally; that is, when one species is first used as the father and then as the mother. The fertility of varieties when intercrossed and of their mongrel offspring cannot be considered as universal; nor is their very general fertility surprising when we remember that it is not likely that either their constitutions or their reproductive systems should have been profoundly modified. Moreover, most of the varieties which have been experimentised on have been {461} produced under domestication; and as domestication (I do not mean mere confinement) apparently tends to eliminate sterility, we ought not to expect it also to produce sterility. The sterility of hybrids is a very different case from that of first crosses, for their reproductive organs are more or less functionally impotent; whereas in first crosses the organs on both sides are in a perfect condition. As we continually see that organisms of all kinds are rendered in some degree sterile from their constitutions having been disturbed by slightly different and new conditions of life, we need not feel surprise at hybrids being in some degree sterile, for their constitutions can hardly fail to have been disturbed from being compounded of two distinct organisations. This parallelism is supported by another parallel, but directly opposite, class of facts; namely, that the vigour and fertility of all organic beings are increased by slight changes in their conditions of life, and that the offspring of slightly modified forms or varieties acquire from being crossed increased vigour and fertility. So that, on the one hand, considerable changes in the conditions of life and crosses between greatly modified forms, lessen fertility; and on the other hand, lesser changes in the conditions of life and crosses between less modified forms, increase fertility. Turning to geographical distribution, the difficulties encountered on the theory of descent with modification are grave enough. All the individuals of the same species, and all the species of the same genus, or even higher group, must have descended from common parents; and therefore, in however distant and isolated parts of the world they are now found, they must in the course of successive generations have passed from some one part to the others. We are often wholly unable {462} even to conjecture how this could have been effected. Yet, as we have reason to believe that some species have retained the same specific form for very long periods, enormously long as measured by years, too much stress ought not to be laid on the occasional wide diffusion of the same species; for during very long periods of time there will always have been a good chance for wide migration by many means. A broken or interrupted range may often be accounted for by the extinction of the species in the intermediate regions. It cannot be denied that we are as yet very ignorant of the full extent of the various climatal and geographical changes which have affected the earth during modern periods; and such changes will obviously have greatly facilitated migration. As an example, I have attempted to show how potent has been the influence of the Glacial period on the distribution both of the same and of representative species throughout the world. We are as yet profoundly ignorant of the many occasional means of transport. With respect to distinct species of the same genus inhabiting very distant and isolated regions, as the process of modification has necessarily been slow, all the means of migration will have been possible during a very long period; and consequently the difficulty of the wide diffusion of species of the same genus is in some degree lessened. As on the theory of natural selection an interminable number of intermediate forms must have existed, linking together all the species in each group by gradations as fine as our present varieties, it may be asked, Why do we not see these linking forms all around us? Why are not all organic beings blended together in an inextricable chaos? With respect to existing forms, we should remember that we have no right to expect (excepting in rare cases) to discover _directly_ connecting {463} links between them, but only between each and some extinct and supplanted form. Even on a wide area, which has during a long period remained continuous, and of which the climate and other conditions of life change insensibly in going from a district occupied by one species into another district occupied by a closely allied species, we have no just right to expect often to find intermediate varieties in the intermediate zone. For we have reason to believe that only a few species are undergoing change at any one period; and all changes are slowly effected. I have also shown that the intermediate varieties which will at first probably exist in the intermediate zones, will be liable to be supplanted by the allied forms on either hand; and the latter, from existing in greater numbers, will generally be modified and improved at a quicker rate than the intermediate varieties, which exist in lesser numbers; so that the intermediate varieties will, in the long run, be supplanted and exterminated. On this doctrine of the extermination of an infinitude of connecting links, between the living and extinct inhabitants of the world, and at each successive period between the extinct and still older species, why is not every geological formation charged with such links? Why does not every collection of fossil remains afford plain evidence of the gradation and mutation of the forms of life? We meet with no such evidence, and this is the most obvious and forcible of the many objections which may be urged against my theory. Why, again, do whole groups of allied species appear, though certainly they often falsely appear, to have come in suddenly on the several geological stages? Why do we not find great piles of strata beneath the Silurian system, stored with the remains of the progenitors of the Silurian groups of fossils? For certainly on my theory such {464} strata must somewhere have been deposited at these ancient and utterly unknown epochs in the world's history. I can answer these questions and grave objections only on the supposition that the geological record is far more imperfect than most geologists believe. It cannot be objected that there has not been time sufficient for any amount of organic change; for the lapse of time has been so great as to be utterly inappreciable by the human intellect. The number of specimens in all our museums is absolutely as nothing compared with the countless generations of countless species which certainly have existed. We should not be able to recognise a species as the parent of any one or more species if we were to examine them ever so closely, unless we likewise possessed many of the intermediate links between their past or parent and present states; and these many links we could hardly ever expect to discover, owing to the imperfection of the geological record. Numerous existing doubtful forms could be named which are probably varieties; but who will pretend that in future ages so many fossil links will be discovered, that naturalists will be able to decide, on the common view, whether or not these doubtful forms are varieties? As long as most of the links between any two species are unknown, if any one link or intermediate variety be discovered, it will simply be classed as another and distinct species. Only a small portion of the world has been geologically explored. Only organic beings of certain classes can be preserved in a fossil condition, at least in any great number. Widely ranging species vary most, and varieties are often at first local,--both causes rendering the discovery of intermediate links less likely. Local varieties will not spread into other and distant regions until they are considerably modified and {465} improved; and when they do spread, if discovered in a geological formation, they will appear as if suddenly created there, and will be simply classed as new species. Most formations have been intermittent in their accumulation; and their duration, I am inclined to believe, has been shorter than the average duration of specific forms. Successive formations are separated from each other by enormous blank intervals of time; for fossiliferous formations, thick enough to resist future degradation, can be accumulated only where much sediment is deposited on the subsiding bed of the sea. During the alternate periods of elevation and of stationary level the record will be blank. During these latter periods there will probably be more variability in the forms of life; during periods of subsidence, more extinction. With respect to the absence of fossiliferous formations beneath the lowest Silurian strata, I can only recur to the hypothesis given in the ninth chapter. That the geological record is imperfect all will admit; but that it is imperfect to the degree which I require, few will be inclined to admit. If we look to long enough intervals of time, geology plainly declares that all species have changed; and they have changed in the manner which my theory requires, for they have changed slowly and in a graduated manner. We clearly see this in the fossil remains from consecutive formations invariably being much more closely related to each other, than are the fossils from formations distant from each other in time. Such is the sum of the several chief objections and difficulties which may justly be urged against my theory; and I have now briefly recapitulated the answers and explanations which can be given to them. I have felt these difficulties far too heavily during many years to {466} doubt their weight. But it deserves especial notice that the more important objections relate to questions on which we are confessedly ignorant; nor do we know how ignorant we are. We do not know all the possible transitional gradations between the simplest and the most perfect organs; it cannot be pretended that we know all the varied means of Distribution during the long lapse of years, or that we know how imperfect the Geological Record is. Grave as these several difficulties are, in my judgment they do not overthrow the theory of descent from a few created forms with subsequent modification. Now let us turn to the other side of the argument. Under domestication we see much variability. This seems to be mainly due to the reproductive system being eminently susceptible to changes in the conditions of life; so that this system, when not rendered impotent, fails to reproduce offspring exactly like the parent-form. Variability is governed by many complex laws,--by correlation of growth, by use and disuse, and by the direct action of the physical conditions of life. There is much difficulty in ascertaining how much modification our domestic productions have undergone; but we may safely infer that the amount has been large, and that modifications can be inherited for long periods. As long as the conditions of life remain the same, we have reason to believe that a modification, which has already been inherited for many generations, may continue to be inherited for an almost infinite number of generations. On the other hand we have evidence that variability, when it has once come into play, does not wholly cease; for new varieties are still occasionally produced by our most anciently domesticated productions. {467} Man does not actually produce variability; he only unintentionally exposes organic beings to new conditions of life, and then nature acts on the organisation, and causes variability. But man can and does select the variations given to him by nature, and thus accumulate them in any desired manner. He thus adapts animals and plants for his own benefit or pleasure. He may do this methodically, or he may do it unconsciously by preserving the individuals most useful to him at the time, without any thought of altering the breed. It is certain that he can largely influence the character of a breed by selecting, in each successive generation, individual differences so slight as to be quite inappreciable by an uneducated eye. This process of selection has been the great agency in the production of the most distinct and useful domestic breeds. That many of the breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether very many of them are varieties or aboriginal species. There is no obvious reason why the principles which have acted so efficiently under domestication should not have acted under nature. In the preservation of favoured individuals and races, during the constantly-recurrent Struggle for Existence, we see the most powerful and ever-acting means of selection. The struggle for existence inevitably follows from the high geometrical ratio of increase which is common to all organic beings. This high rate of increase is proved by calculation,--by the rapid increase of many animals and plants during a succession of peculiar seasons, or when naturalised in a new country. More individuals are born than can possibly survive. A grain in the balance will determine which individual shall live and which shall die,--which variety or species shall increase in number, and which {468} shall decrease, or finally become extinct. As the individuals of the same species come in all respects into the closest competition with each other, the struggle will generally be most severe between them; it will be almost equally severe between the varieties of the same species, and next in severity between the species of the same genus. But the struggle will often be very severe between beings most remote in the scale of nature. The slightest advantage in one being, at any age or during any season, over those with which it comes into competition, or better adaptation in however slight a degree to the surrounding physical conditions, will turn the balance. With animals having separated sexes there will in most cases be a struggle between the males for possession of the females. The most vigorous individuals, or those which have most successfully struggled with their conditions of life, will generally leave most progeny. But success will often depend on having special weapons or means of defence, or on the charms of the males; and the slightest advantage will lead to victory. As geology plainly proclaims that each land has undergone great physical changes, we might have expected that organic beings would have varied under nature, in the same way as they generally have varied under the changed conditions of domestication. And if there be any variability under nature, it would be an unaccountable fact if natural selection had not come into play. It has often been asserted, but the assertion is quite incapable of proof, that the amount of variation under nature is a strictly limited quantity. Man, though acting on external characters alone and often capriciously, can produce within a short period a great result by adding up mere individual differences in his domestic productions; and every one admits that there are at least individual differences in species under {469} nature. But, besides such differences, all naturalists have admitted the existence of varieties, which they think sufficiently distinct to be worthy of record in systematic works. No one can draw any clear distinction between individual differences and slight varieties; or between more plainly marked varieties and sub-species, and species. Let it be observed how naturalists differ in the rank which they assign to the many representative forms in Europe and North America. If then we have under nature variability and a powerful agent always ready to act and select, why should we doubt that variations in any way useful to beings, under their excessively complex relations of life, would be preserved, accumulated, and inherited? Why, if man can by patience select variations most useful to himself, should nature fail in selecting variations useful, under changing conditions of life, to her living products? What limit can be put to this power, acting during long ages and rigidly scrutinising the whole constitution, structure, and habits of each creature,--favouring the good and rejecting the bad? I can see no limit to this power, in slowly and beautifully adapting each form to the most complex relations of life. The theory of natural selection, even if we looked no further than this, seems to me to be in itself probable. I have already recapitulated, as fairly as I could, the opposed difficulties and objections: now let us turn to the special facts and arguments in favour of the theory. On the view that species are only strongly marked and permanent varieties, and that each species first existed as a variety, we can see why it is that no line of demarcation can be drawn between species, commonly supposed to have been produced by special acts of creation, and varieties which are acknowledged to have been produced by secondary laws. On this same {470} view we can understand how it is that in each region where many species of a genus have been produced, and where they now flourish, these same species should present many varieties; for where the manufactory of species has been active, we might expect, as a general rule, to find it still in action; and this is the case if varieties be incipient species. Moreover, the species of the larger genera, which afford the greater number of varieties or incipient species, retain to a certain degree the character of varieties; for they differ from each other by a less amount of difference than do the species of smaller genera. The closely allied species also of the larger genera apparently have restricted ranges, and in their affinities they are clustered in little groups round other species--in which respects they resemble varieties. These are strange relations on the view of each species having been independently created, but are intelligible if all species first existed as varieties. As each species tends by its geometrical ratio of reproduction to increase inordinately in number; and as the modified descendants of each species will be enabled to increase by so much the more as they become diversified in habits and structure, so as to be enabled to seize on many and widely different places in the economy of nature, there will be a constant tendency in natural selection to preserve the most divergent offspring of any one species. Hence during a long-continued course of modification, the slight differences, characteristic of varieties of the same species, tend to be augmented into the greater differences characteristic of species of the same genus. New and improved varieties will inevitably supplant and exterminate the older, less improved and intermediate varieties; and thus species are rendered to a large extent defined and distinct objects. Dominant species belonging to the {471} larger groups tend to give birth to new and dominant forms; so that each large group tends to become still larger, and at the same time more divergent in character. But as all groups cannot thus succeed in increasing in size, for the world would not hold them, the more dominant groups beat the less dominant. This tendency in the large groups to go on increasing in size and diverging in character, together with the almost inevitable contingency of much extinction, explains the arrangement of all the forms of life, in groups subordinate to groups, all within a few great classes, which we now see everywhere around us, and which has prevailed throughout all time. This grand fact of the grouping of all organic beings seems to me utterly inexplicable on the theory of creation. As natural selection acts solely by accumulating slight, successive, favourable variations, it can produce no great or sudden modification; it can act only by very short and slow steps. Hence the canon of "Natura non facit saltum," which every fresh addition to our knowledge tends to make truer, is on this theory simply intelligible. We can plainly see why nature is prodigal in variety, though niggard in innovation. But why this should be a law of nature if each species has been independently created, no man can explain. Many other facts are, as it seems to me, explicable on this theory. How strange it is that a bird, under the form of woodpecker, should have been created to prey on insects on the ground; that upland geese, which never or rarely swim, should have been created with webbed feet; that a thrush should have been created to dive and feed on sub-aquatic insects; and that a petrel should have been created with habits and structure fitting it for the life of an auk or grebe! and so on in endless other cases. But on the view of each {472} species constantly trying to increase in number, with natural selection always ready to adapt the slowly varying descendants of each to any unoccupied or ill-occupied place in nature, these facts cease to be strange, or perhaps might even have been anticipated. As natural selection acts by competition, it adapts the inhabitants of each country only in relation to the degree of perfection of their associates; so that we need feel no surprise at the inhabitants of any one country, although on the ordinary view supposed to have been specially created and adapted for that country, being beaten and supplanted by the naturalised productions from another land. Nor ought we to marvel if all the contrivances in nature be not, as far as we can judge, absolutely perfect; and if some of them be abhorrent to our ideas of fitness. We need not marvel at the sting of the bee causing the bee's own death; at drones being produced in such vast numbers for one single act, with the great majority slaughtered by their sterile sisters; at the astonishing waste of pollen by our fir-trees; at the instinctive hatred of the queen bee for her own fertile daughters; at ichneumonidæ feeding within the live bodies of caterpillars; and at other such cases. The wonder indeed is, on the theory of natural selection, that more cases of the want of absolute perfection have not been observed. The complex and little known laws governing variation are the same, as far as we can see, with the laws which have governed the production of so-called specific forms. In both cases physical conditions seem to have produced but little direct effect; yet when varieties enter any zone, they occasionally assume some of the characters of the species proper to that zone. In both varieties and species, use and disuse seem to have produced some effect; for it is difficult to resist this {473} conclusion when we look, for instance, at the logger-headed duck, which has wings incapable of flight, in nearly the same condition as in the domestic duck; or when we look at the burrowing tucutucu, which is occasionally blind, and then at certain moles, which are habitually blind and have their eyes covered with skin; or when we look at the blind animals inhabiting the dark caves of America and Europe. In both varieties and species correlation of growth seems to have played a most important part, so that when one part has been modified other parts are necessarily modified. In both varieties and species reversions to long-lost characters occur. How inexplicable on the theory of creation is the occasional appearance of stripes on the shoulder and legs of the several species of the horse-genus and in their hybrids! How simply is this fact explained if we believe that these species have descended from a striped progenitor, in the same manner as the several domestic breeds of pigeon have descended from the blue and barred rock-pigeon! On the ordinary view of each species having been independently created, why should the specific characters, or those by which the species of the same genus differ from each other, be more variable than the generic characters in which they all agree? Why, for instance, should the colour of a flower be more likely to vary in any one species of a genus, if the other species, supposed to have been created independently, have differently coloured flowers, than if all the species of the genus have the same coloured flowers? If species are only well-marked varieties, of which the characters have become in a high degree permanent, we can understand this fact; for they have already varied since they branched off from a common progenitor in certain characters, by which they have come to be specifically distinct from each other; {474} and therefore these same characters would be more likely still to be variable than the generic characters which have been inherited without change for an enormous period. It is inexplicable on the theory of creation why a part developed in a very unusual manner in any one species of a genus, and therefore, as we may naturally infer, of great importance to the species, should be eminently liable to variation; but, on my view, this part has undergone, since the several species branched off from a common progenitor, an unusual amount of variability and modification, and therefore we might expect this part generally to be still variable. But a part may be developed in the most unusual manner, like the wing of a bat, and yet not be more variable than any other structure, if the part be common to many subordinate forms, that is, if it has been inherited for a very long period; for in this case it will have been rendered constant by long-continued natural selection. Glancing at instincts, marvellous as some are, they offer no greater difficulty than does corporeal structure on the theory of the natural selection of successive, slight, but profitable modifications. We can thus understand why nature moves by graduated steps in endowing different animals of the same class with their several instincts. I have attempted to show how much light the principle of gradation throws on the admirable architectural powers of the hive-bee. Habit no doubt sometimes comes into play in modifying instincts; but it certainly is not indispensable, as we see, in the case of neuter insects, which leave no progeny to inherit the effects of long-continued habit. On the view of all the species of the same genus having descended from a common parent, and having inherited much in common, we can understand how it is that allied species, when placed under considerably different conditions of life, {475} yet should follow nearly the same instincts; why the thrush of South America, for instance, lines her nest with mud like our British species. On the view of instincts having been slowly acquired through natural selection we need not marvel at some instincts being apparently not perfect and liable to mistakes, and at many instincts causing other animals to suffer. If species be only well-marked and permanent varieties, we can at once see why their crossed offspring should follow the same complex laws in their degrees and kinds of resemblance to their parents,--in being absorbed into each other by successive crosses, and in other such points,--as do the crossed offspring of acknowledged varieties. On the other hand, these would be strange facts if species have been independently created, and varieties have been produced by secondary laws. If we admit that the geological record is imperfect in an extreme degree, then such facts as the record gives, support the theory of descent with modification. New species have come on the stage slowly and at successive intervals; and the amount of change, after equal intervals of time, is widely different in different groups. The extinction of species and of whole groups of species, which has played so conspicuous a part in the history of the organic world, almost inevitably follows on the principle of natural selection; for old forms will be supplanted by new and improved forms. Neither single species nor groups of species reappear when the chain of ordinary generation has once been broken. The gradual diffusion of dominant forms, with the slow modification of their descendants, causes the forms of life, after long intervals of time, to appear as if they had changed simultaneously throughout the world. The fact of the fossil remains of each formation being in some degree intermediate in character between the {476} fossils in the formations above and below, is simply explained by their intermediate position in the chain of descent. The grand fact that all extinct organic beings belong to the same system with recent beings, falling either into the same or into intermediate groups, follows from the living and the extinct being the offspring of common parents. As the groups which have descended from an ancient progenitor have generally diverged in character, the progenitor with its early descendants will often be intermediate in character in comparison with its later descendants; and thus we can see why the more ancient a fossil is, the oftener it stands in some degree intermediate between existing and allied groups. Recent forms are generally looked at as being, in some vague sense, higher than ancient and extinct forms; and they are in so far higher as the later and more improved forms have conquered the older and less improved organic beings in the struggle for life. Lastly, the law of the long endurance of allied forms on the same continent,--of marsupials in Australia, of edentata in America, and other such cases,--is intelligible, for within a confined country, the recent and the extinct will naturally be allied by descent. Looking to geographical distribution, if we admit that there has been during the long course of ages much migration from one part of the world to another, owing to former climatal and geographical changes and to the many occasional and unknown means of dispersal, then we can understand, on the theory of descent with modification, most of the great leading facts in Distribution. We can see why there should be so striking a parallelism in the distribution of organic beings throughout space, and in their geological succession throughout time; for in both cases the beings have been connected by the bond of ordinary generation, and the means of {477} modification have been the same. We see the full meaning of the wonderful fact, which must have struck every traveller, namely, that on the same continent, under the most diverse conditions, under heat and cold, on mountain and lowland, on deserts and marshes, most of the inhabitants within each great class are plainly related; for they will generally be descendants of the same progenitors and early colonists. On this same principle of former migration, combined in most cases with modification, we can understand, by the aid of the Glacial period, the identity of some few plants, and the close alliance of many others, on the most distant mountains, under the most different climates; and likewise the close alliance of some of the inhabitants of the sea in the northern and southern temperate zones, though separated by the whole intertropical ocean. Although two areas may present the same physical conditions of life, we need feel no surprise at their inhabitants being widely different, if they have been for a long period completely separated from each other; for as the relation of organism to organism is the most important of all relations, and as the two areas will have received colonists from some third source or from each other, at various periods and in different proportions, the course of modification in the two areas will inevitably be different. On this view of migration, with subsequent modification, we can see why oceanic islands should be inhabited by few species, but of these, that many should be peculiar. We can clearly see why those animals which cannot cross wide spaces of ocean, as frogs and terrestrial mammals, should not inhabit oceanic islands; and why, on the other hand, new and peculiar species of bats, which can traverse the ocean, should so often be found on islands far distant from any continent. Such facts {478} as the presence of peculiar species of bats, and the absence of all other mammals, on oceanic islands, are utterly inexplicable on the theory of independent acts of creation. The existence of closely allied or representative species in any two areas, implies, on the theory of descent with modification, that the same parents formerly inhabited both areas; and we almost invariably find that wherever many closely allied species inhabit two areas, some identical species common to both still exist. Wherever many closely allied yet distinct species occur, many doubtful forms and varieties of the same species likewise occur. It is a rule of high generality that the inhabitants of each area are related to the inhabitants of the nearest source whence immigrants might have been derived. We see this in nearly all the plants and animals of the Galapagos archipelago, of Juan Fernandez, and of the other American islands being related in the most striking manner to the plants and animals of the neighbouring American mainland; and those of the Cape de Verde archipelago and other African islands to the African mainland. It must be admitted that these facts receive no explanation on the theory of creation. The fact, as we have seen, that all past and present organic beings constitute one grand natural system, with group subordinate to group, and with extinct groups often falling in between recent groups, is intelligible on the theory of natural selection with its contingencies of extinction and divergence of character. On these same principles we see how it is, that the mutual affinities of the species and genera within each class are so complex and circuitous. We see why certain characters are far more serviceable than others for classification;--why adaptive characters, though of paramount importance to the being, are of hardly any {479} importance in classification; why characters derived from rudimentary parts, though of no service to the being, are often of high classificatory value; and why embryological characters are the most valuable of all. The real affinities of all organic beings are due to inheritance or community of descent. The natural system is a genealogical arrangement, in which we have to discover the lines of descent by the most permanent characters, however slight their vital importance may be. The framework of bones being the same in the hand of a man, wing of a bat, fin of the porpoise, and leg of the horse,--the same number of vertebræ forming the neck of the giraffe and of the elephant,--and innumerable other such facts, at once explain themselves on the theory of descent with slow and slight successive modifications. The similarity of pattern in the wing and leg of a bat, though used for such different purpose,--in the jaws and legs of a crab,--in the petals, stamens, and pistils of a flower, is likewise intelligible on the view of the gradual modification of parts or organs, which were alike in the early progenitor of each class. On the principle of successive variations not always supervening at an early age, and being inherited at a corresponding not early period of life, we can clearly see why the embryos of mammals, birds, reptiles, and fishes should be so closely alike, and should be so unlike the adult forms. We may cease marvelling at the embryo of an air-breathing mammal or bird having branchial slits and arteries running in loops, like those in a fish which has to breathe the air dissolved in water, by the aid of well-developed branchiæ. Disuse, aided sometimes by natural selection, will often tend to reduce an organ, when it has become useless by changed habits or under changed conditions {480} of life; and we can clearly understand on this view the meaning of rudimentary organs. But disuse and selection will generally act on each creature, when it has come to maturity and has to play its full part in the struggle for existence, and will thus have little power of acting on an organ during early life; hence the organ will not be much reduced or rendered rudimentary at this early age. The calf, for instance, has inherited teeth, which never cut through the gums of the upper jaw, from an early progenitor having well-developed teeth; and we may believe, that the teeth in the mature animal were reduced, during successive generations, by disuse or by the tongue and palate having been better fitted by natural selection to browse without their aid; whereas in the calf, the teeth have been left untouched by selection or disuse, and on the principle of inheritance at corresponding ages have been inherited from a remote period to the present day. On the view of each organic being and each separate organ having been specially created, how utterly inexplicable it is that parts, like the teeth in the embryonic calf or like the shrivelled wings under the soldered wing-covers of some beetles, should thus so frequently bear the plain stamp of inutility! Nature may be said to have taken pains to reveal, by rudimentary organs and by homologous structures, her scheme of modification, which it seems that we wilfully will not understand. I have now recapitulated the chief facts and considerations which have thoroughly convinced me that species have been modified, during a long course of descent, by the preservation or the natural selection of many successive slight favourable variations. I cannot believe that a false theory would explain, as it seems to me that the theory of natural selection does explain, {481} the several large classes of facts above specified. I see no good reason why the views given in this volume should shock the religious feelings of any one. A celebrated author and divine has written to me that "he has gradually learnt to see that it is just as noble a conception of the Deity to believe that He created a few original forms capable of self-development into other and needful forms, as to believe that He required a fresh act of creation to supply the voids caused by the action of His laws." Why, it may be asked, have all the most eminent living naturalists and geologists rejected this view of the mutability of species? It cannot be asserted that organic beings in a state of nature are subject to no variation; it cannot be proved that the amount of variation in the course of long ages is a limited quantity; no clear distinction has been, or can be, drawn between species and well-marked varieties. It cannot be maintained that species when intercrossed are invariably sterile, and varieties invariably fertile; or that sterility is a special endowment and sign of creation. The belief that species were immutable productions was almost unavoidable as long as the history of the world was thought to be of short duration; and now that we have acquired some idea of the lapse of time, we are too apt to assume, without proof, that the geological record is so perfect that it would have afforded us plain evidence of the mutation of species, if they had undergone mutation. But the chief cause of our natural unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting any great change of which we do not see the intermediate steps. The difficulty is the same as that felt by so many geologists, when Lyell first insisted that long {482} lines of inland cliffs had been formed, and great valleys excavated, by the slow action of the coast-waves. The mind cannot possibly grasp the full meaning of the term of a hundred million years; it cannot add up and perceive the full effects of many slight variations, accumulated during an almost infinite number of generations. Although I am fully convinced of the truth of the views given in this volume under the form of an abstract, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as the "plan of creation," "unity of design," &c., and to think that we give an explanation when we only restate a fact. Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject my theory. A few naturalists, endowed with much flexibility of mind, and who have already begun to doubt on the immutability of species, may be influenced by this volume; but I look with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality. Whoever is led to believe that species are mutable will do good service by conscientiously expressing his conviction; for only thus can the load of prejudice by which this subject is overwhelmed be removed. Several eminent naturalists have of late published their belief that a multitude of reputed species in each genus are not real species; but that other species are real, that is, have been independently created. This seems to me a strange conclusion to arrive at. They admit that a multitude of forms, which till lately {483} they themselves thought were special creations, and which are still thus looked at by the majority of naturalists, and which consequently have every external characteristic feature of true species,--they admit that these have been produced by variation, but they refuse to extend the same view to other and very slightly different forms. Nevertheless they do not pretend that they can define, or even conjecture, which are the created forms of life, and which are those produced by secondary laws. They admit variation as a _vera causa_ in one case, they arbitrarily reject it in another, without assigning any distinction in the two cases. The day will come when this will be given as a curious illustration of the blindness of preconceived opinion. These authors seem no more startled at a miraculous act of creation than at an ordinary birth. But do they really believe that at innumerable periods in the earth's history certain elemental atoms have been commanded suddenly to flash into living tissues? Do they believe that at each supposed act of creation one individual or many were produced? Were all the infinitely numerous kinds of animals and plants created as eggs or seed, or as full grown? and in the case of mammals, were they created bearing the false marks of nourishment from the mother's womb? Although naturalists very properly demand a full explanation of every difficulty from those who believe in the mutability of species, on their own side they ignore the whole subject of the first appearance of species in what they consider reverent silence. It may be asked how far I extend the doctrine of the modification of species. The question is difficult to answer, because the more distinct the forms are which we may consider, by so much the arguments fall away in force. But some arguments of the greatest weight {484} extend very far. All the members of whole classes can be connected together by chains of affinities, and all can be classified on the same principle, in groups subordinate to groups. Fossil remains sometimes tend to fill up very wide intervals between existing orders. Organs in a rudimentary condition plainly show that an early progenitor had the organ in a fully developed state; and this in some instances necessarily implies an enormous amount of modification in the descendants. Throughout whole classes various structures are formed on the same pattern, and at an embryonic age the species closely resemble each other. Therefore I cannot doubt that the theory of descent with modification embraces all the members of the same class. I believe that animals have descended from at most only four or five progenitors, and plants from an equal or lesser number. Analogy would lead me one step further, namely, to the belief that all animals and plants have descended from some one prototype. But analogy may be a deceitful guide. Nevertheless all living things have much in common, in their chemical composition, their germinal vesicles, their cellular structure, and their laws of growth and reproduction. We see this even in so trifling a circumstance as that the same poison often similarly affects plants and animals; or that the poison secreted by the gall-fly produces monstrous growths on the wild rose or oak-tree. Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed by the Creator. When the views advanced by me in this volume, and by Mr. Wallace in the Linnean Journal, or when analogous views on the origin of species are generally {485} admitted, we can dimly foresee that there will be a considerable revolution in natural history. Systematists will be able to pursue their labours as at present; but they will not be incessantly haunted by the shadowy doubt whether this or that form be in essence a species. This I feel sure, and I speak after experience, will be no slight relief. The endless disputes whether or not some fifty species of British brambles are true species will cease. Systematists will have only to decide (not that this will be easy) whether any form be sufficiently constant and distinct from other forms, to be capable of definition; and if definable, whether the differences be sufficiently important to deserve a specific name. This latter point will become a far more essential consideration than it is at present; for differences, however slight, between any two forms, if not blended by intermediate gradations, are looked at by most naturalists as sufficient to raise both forms to the rank of species. Hereafter we shall be compelled to acknowledge that the only distinction between species and well-marked varieties is, that the latter are known, or believed, to be connected at the present day by intermediate gradations, whereas species were formerly thus connected. Hence, without rejecting the consideration of the present existence of intermediate gradations between any two forms, we shall be led to weigh more carefully and to value higher the actual amount of difference between them. It is quite possible that forms now generally acknowledged to be merely varieties may hereafter be thought worthy of specific names, as with the primrose and cowslip; and in this case scientific and common language will come into accordance. In short, we shall have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial combinations {486} made for convenience. This may not be a cheering prospect; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species. The other and more general departments of natural history will rise greatly in interest. The terms used by naturalists of affinity, relationship, community of type, paternity, morphology, adaptive characters, rudimentary and aborted organs, &c., will cease to be metaphorical, and will have a plain signification. When we no longer look at an organic being as a savage looks at a ship, as at something wholly beyond his comprehension; when we regard every production of nature as one which has had a history; when we contemplate every complex structure and instinct as the summing up of many contrivances, each useful to the possessor, nearly in the same way as when we look at any great mechanical invention as the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen; when we thus view each organic being, how far more interesting, I speak from experience, will the study of natural history become! A grand and almost untrodden field of inquiry will be opened, on the causes and laws of variation, on correlation of growth, on the effects of use and disuse, on the direct action of external conditions, and so forth. The study of domestic productions will rise immensely in value. A new variety raised by man will be a more important and interesting subject for study than one more species added to the infinitude of already recorded species. Our classifications will come to be, as far as they can be so made, genealogies; and will then truly give what may be called the plan of creation. The rules for classifying will no doubt become simpler when we have a definite object in view. We possess no {487} pedigrees or armorial bearings; and we have to discover and trace the many diverging lines of descent in our natural genealogies, by characters of any kind which have long been inherited. Rudimentary organs will speak infallibly with respect to the nature of long-lost structures. Species and groups of species, which are called aberrant, and which may fancifully be called living fossils, will aid us in forming a picture of the ancient forms of life. Embryology will reveal to us the structure, in some degree obscured, of the prototypes of each great class. When we can feel assured that all the individuals of the same species, and all the closely allied species of most genera, have within a not very remote period descended from one parent, and have migrated from some one birthplace; and when we better know the many means of migration, then, by the light which geology now throws, and will continue to throw, on former changes of climate and of the level of the land, we shall surely be enabled to trace in an admirable manner the former migrations of the inhabitants of the whole world. Even at present, by comparing the differences of the inhabitants of the sea on the opposite sides of a continent, and the nature of the various inhabitants of that continent in relation to their apparent means of immigration, some light can be thrown on ancient geography. The noble science of Geology loses glory from the extreme imperfection of the record. The crust of the earth with its embedded remains must not be looked at as a well-filled museum, but as a poor collection made at hazard and at rare intervals. The accumulation of each great fossiliferous formation will be recognised as having depended on an unusual concurrence of circumstances, and the blank intervals between the successive stages as having been of vast duration. But we shall {488} be able to gauge with some security the duration of these intervals by a comparison of the preceding and succeeding organic forms. We must be cautious in attempting to correlate as strictly contemporaneous two formations, which include few identical species, by the general succession of their forms of life. As species are produced and exterminated by slowly acting and still existing causes, and not by miraculous acts of creation and by catastrophes; and as the most important of all causes of organic change is one which is almost independent of altered and perhaps suddenly altered physical conditions, namely, the mutual relation of organism to organism,--the improvement of one being entailing the improvement or the extermination of others; it follows, that the amount of organic change in the fossils of consecutive formations probably serves as a fair measure of the lapse of actual time. A number of species, however, keeping in a body might remain for a long period unchanged, whilst within this same period, several of these species, by migrating into new countries and coming into competition with foreign associates, might become modified; so that we must not overrate the accuracy of organic change as a measure of time. During early periods of the earth's history, when the forms of life were probably fewer and simpler, the rate of change was probably slower; and at the first dawn of life, when very few forms of the simplest structure existed, the rate of change may have been slow in an extreme degree. The whole history of the world, as at present known, although of a length quite incomprehensible by us, will hereafter be recognised as a mere fragment of time, compared with the ages which have elapsed since the first creature, the progenitor of innumerable extinct and living descendants, was created. In the distant future I see open fields for far more {489} important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history. Authors of the highest eminence seem to be fully satisfied with the view that each species has been independently created. To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual. When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Silurian system was deposited, they seem to me to become ennobled. Judging from the past, we may safely infer that not one living species will transmit its unaltered likeness to a distant futurity. And of the species now living very few will transmit progeny of any kind to a far distant futurity; for the manner in which all organic beings are grouped, shows that the greater number of species of each genus, and all the species of many genera, have left no descendants, but have become utterly extinct. We can so far take a prophetic glance into futurity as to foretel that it will be the common and widely-spread species, belonging to the larger and dominant groups, which will ultimately prevail and procreate new and dominant species. As all the living forms of life are the lineal descendants of those which lived long before the Silurian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no cataclysm has desolated the whole world. Hence we may look with some confidence to a secure future of equally inappreciable length. And as natural selection works {490} solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection. It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the external conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. * * * * * {491} INDEX. A. Aberrant groups, 429. Abyssinia, plants of, 375. Acclimatisation, 139. Affinities of extinct species, 329. ---- of organic beings, 411. Agassiz on Amblyopsis, 139. ---- on groups of species suddenly appearing, 302, 305. ---- on embryological succession, 338. ---- on the glacial period, 366. ---- on embryological characters, 418. ---- on the embryos of vertebrata, 439. ---- on parallelism of embryological development and geological succession, 449. Algæ of New Zealand, 376. Alligators, males, fighting, 88. Amblyopsis, blind fish, 139. America, North, productions allied to those of Europe, 371. --------, boulders and glaciers of, 373. ----, South, no modern formations on west coast, 290. Ammonites, sudden extinction of, 321. Anagallis, sterility of, 247. Analogy of variations, 159. Ancylus, 386. Animals, not domesticated from being variable, 17. ----, domestic, descended from several stocks, 19. --------, acclimatisation of, 141. ---- of Australia, 116. ---- with thicker fur in cold climates, 133. ----, blind, in caves, 137. ----, extinct, of Australia, 339. Anomma, 240. Antarctic islands, ancient flora of, 399. Antirrhinum, 161. Ants attending aphides, 210. ----, slave-making instinct, 219. ----, neuter, structure of, 236. Aphides, attended by ants, 210. Aphis, development of, 442. Apteryx, 182. Arab horses, 35. Aralo-Caspian Sea, 339. Archaic, M. de, on the succession of species, 325. Artichoke, Jerusalem, 142. Ascension, plants of, 389. Asclepias, pollen of, 193. Asparagus, 359. Aspicarpa, 417. Asses, striped, 163. Ateuchus, 135. Audubon on habits of frigate-bird, 185. ---- on variation in birds'-nests, 212. ---- on heron eating seeds, 387. Australia, animals of, 116. ----. dogs of, 215. ----, extinct animals of, 339. ----, European plants in, 375. Azara on flies destroying cattle, 72. Azores, flora of, 363. B. Babington, Mr., on British plants, 48. Balancement of growth, 147. Bamboo with hooks, 197. Barberry, flowers of, 98. Barrande, M., on Silurian colonies, 313. ---- on the succession of species, 325. ---- on parallelism of palæozoic formations, 328. ---- on affinities of ancient species, 330. Barriers, importance of, 347. Batrachians on islands, 393. Bats, how structure acquired, 180. ----, distribution of, 394. Bear, catching water-insects, 184. Bee, sting of, 202. ----, queen, killing rivals, 202. Bees fertilising flowers, 73. ----, hive, not sucking the red clover, 95. {492} --------, cell-making instinct, 224. ----, humble, cells of, 225. ----, parasitic, 218. Beetles, wingless, in Madeira, 135. ---- with deficient tarsi, 135. Bentham, Mr., on British plants, 48. ----, on classification, 419. Berkeley, Mr., on seeds in salt-water, 358. Bermuda, birds of, 391. Birds acquiring fear, 212. ---- annually cross the Atlantic, 364. ----, colour of, on continents, 132. ----, footsteps and remains of, in secondary rocks, 304. ----, fossil, in caves of Brazil, 339. ---- of Madeira, Bermuda, and Galapagos, 391. ----, song of males, 89. ---- transporting seeds, 361. ----, waders, 385. ----, wingless, 134, 182. ----, with traces of embryonic teeth, 450. Bizcacha, 349. ----, affinities of, 429. Bladder for swimming in fish, 190. Blindness of cave animals, 137. Blyth, Mr., on distinctness of Indian cattle, 18. ----, on striped Hemionus, 163. ----, on crossed geese, 254. Boar, shoulder-pad of, 88. Borrow, Mr., on the Spanish pointer, 35. Bory St. Vincent on Batrachians, 393. Bosquet, M., on fossil Chthamalus, 305. Boulders, erratic, on the Azores, 363. Branchiæ, 190. Brent, Mr., on house-tumblers, 214. ----, on hawks killing pigeons, 362. Brewer, Dr., on American cuckoo, 217. Britain, mammals of, 396. Bronn on duration of specific forms, 294. Brown, Robert, on classification, 415. Buckman on variation in plants, 10. Buzareingues on sterility of varieties, 270. C. Cabbage, varieties of, crossed, 99. Calceolaria, 251. Canary-birds, sterility of hybrids, 252. Cape de Verde islands, 398. Cape of Good Hope, plants of, 110, 375. Carrier-pigeons killed by hawks, 362. Cassini on flowers of compositæ, 145. Catasetum, 424. Cats, with blue eyes, deaf, 12. ----, variation in habits of, 91. ---- curling tail when going to spring, 201. Cattle destroying fir-trees, 72. ---- destroyed by flies in La Plata, 72. ----, breeds of, locally extinct, 111. ----, fertility of Indian and European breeds, 254. Cave, inhabitants of, blind, 137. Centres of creation, 352. Cephalopodæ, development of, 442. Cervulus, 253. Cetacea, teeth and hair, 144. Ceylon, plants of, 375. Chalk formation, 322. Characters, divergence of, 111. ----, sexual, variable, 156. ----, adaptive or analogical, 426. Charlock, 76. Checks to increase, 67. ---- ----, mutual, 71. Chickens, instinctive tameness of, 216. Chthamalinæ, 289. Chthamalus, cretacean species of, 305. Circumstances favourable to selection of domestic products, 40. ---- ---- to natural selection, 102. Cirripedes capable of crossing, 101. ----, carapace aborted, 148. ----, their ovigerous frena, 192. ----, fossil, 304. ----, larvæ of, 440. Classification, 413. Clift, Mr., on the succession of types, 339. Climate, effects of, in checking increase of beings, 68. ----, adaptation of, to organisms, 139. {493} Cobites, intestine of, 190. Cockroach, 76. Collections, palæontological, poor, 288. Colour, influenced by climate, 132. ----, in relation to attacks by flies, 198. Columba livia, parent of domestic pigeons, 23. Colymbetes, 386. Compensation of growth, 147. Compositæ, outer and inner florets of, 144. ----, male flowers of, 451. Conclusion, general, 480. Conditions, slight changes in, favourable to fertility, 267. Coot, 185. Coral-islands, seeds drifted to, 361. ---- reefs, indicating movements of earth, 310. Corn-crake, 186. Correlation of growth in domestic productions, 11. ---- of growth, 143, 198. Cowslip, 49. Creation, single centres of, 352. Crinum, 250. Crosses, reciprocal, 258. Crossing of domestic animals, importance in altering breeds, 20. ----, advantages of, 96. ---- unfavourable to selection, 102. Crustacea of New Zealand, 376. Crustacean, blind, 137. Cryptocerus, 239. Ctenomys, blind, 137. Cuckoo, instinct of, 216. Currants, grafts of, 262. Currents of sea, rate of, 360. Cuvier on conditions of existence, 206. ---- on fossil monkeys, 304. ----, Fred., on instinct, 208. D. Dana, Prof., on blind cave-animals, 139. ----, on relations of crustaceans of Japan, 372. ----, on crustaceans of New Zealand, 376. De Candolle on struggle for existence, 62. ---- on umbelliferæ, 146. ---- on general affinities, 430. ----, Alph., on low plants, widely dispersed, 406. ----, ----, on widely-ranging plants being variable, 53. ----, ----, on naturalisation, 115. ----, ----, on winged seeds, 146. ----, ----, on Alpine species suddenly becoming rare, 175. ----, ----, on distribution of plants with large seeds, 360. ----, ----, on vegetation of Australia, 379. ----, ----, on fresh-water plants, 386. ----, ----, on insular plants, 389. Degradation of coast-rocks, 282. Denudation, rate of, 285. ---- of oldest rocks, 308. Development of ancient forms, 336. Devonian system, 334. Dianthus, fertility of crosses, 256. Dirt on feet of birds, 362. Dispersal, means of, 356. ---- during glacial period, 365. Distribution, geographical, 346. ----, means of, 356. Disuse, effects of, under nature, 134. Divergence of character, 111. Division, physiological, of labour, 115. Dogs, hairless, with imperfect teeth, 12. ---- descended from several wild stocks, 18. ----, domestic instincts of, 213. ----, inherited civilisation of, 215. ----, fertility of breeds together, 254. ----, ---- of crosses, 268. ----, proportions of, when young, 444. Domestication, variation under, 7. Downing, Mr., on fruit-trees in America, 85. Downs, North and South, 286. Dragon-flies, intestines of, 190. Drift-timber, 360. Driver-ant, 240. Drones killed by other bees, 202. Duck, domestic, wings of, reduced, 11. ----, logger-headed, 182. {494} Duckweed, 385. Dugong, affinities of, 414. Dung-beetles with deficient tarsi, 135. Dyticus, 386. E. Earl, Mr. W., on the Malay Archipelago, 395. Ears, drooping, in domestic animals, 11. ----, rudimentary, 454. Earth, seeds in roots of trees, 361. Eciton, 238. Economy of organisation, 147. Edentata, teeth and hair, 144. ----, fossil species of, 339. Edwards, Milne, on physiological divisions of labour, 115. ----, on gradations of structure, 194. ----, on embryonical characters, 418. Eggs, young birds escaping from, 87. Electric organs, 192. Elephant, rate of increase, 64. ---- of glacial period, 141. Embryology, 438. Existence, struggle for, 60. ----, conditions of, 206. Extinction, as bearing on natural selection, 109. ---- of domestic varieties, 111, ----, 317. Eye, structure of, 187. ----, correction for aberration, 202. Eyes reduced in moles, 137. F. Fabre, M. on parasitic sphex, 218. Falconer, Dr., on naturalisation of plants in India, 65. ---- on fossil crocodile, 313. ---- on elephants and mastodons, 334. ---- and Cautley on mammals of sub-Himalayan beds, 340. Falkland Island, wolf of, 394. Faults, 285. Faunas, marine, 348. Fear, instinctive, in birds, 212. Feet of bird, young molluscs adhering to, 385. Fertility of hybrids, 249. ---- from slight changes in conditions, 267. ---- of crossed varieties, 268. Fir-trees destroyed by cattle, 72. ---- ----, pollen of, 203. Fish, flying, 182. ----, teleostean, sudden appearance of, 305. ---- eating seeds, 362, 387. ----, fresh-water, distribution of, 384. Fishes, ganoid, now confined to fresh water, 107. ----, electric organs of, 192. ----, ganoid, living in fresh water, 321. ---- of southern hemisphere, 376. Flight, powers of, how acquired, 182. Flowers, structure of, in relation to crossing, 97. ---- of compositæ and umbelliferæ, 144. Forbes, E., on colours of shells, 132. ---- on abrupt range of shells in depth, 175. ---- on poorness of palæontological collections, 288. ---- on continuous succession of genera, 316. ---- on continental extensions, 357. ---- on distribution during glacial period, 366. ---- on parallelism in time and space, 409. Forests, changes in, in America, 74. Formation, Devonian, 334. Formations, thickness of, in Britain, 284. ----, intermittent, 290. Formica rufescens, 219. ---- sanguinea, 219. ---- flava, neuter of, 240. Frena, ovigerous, of cirripedes, 192. Fresh-water productions, dispersal of, 383. Fries on species in large genera being closely allied to other species, 57. Frigate-bird, 185. Frogs on islands, 393. Fruit-trees, gradual improvement of, 37. ---- ---- in United States, 85. ---- ----, varieties of, acclimatised in United States, 142. {495} Fuci, crossed, 258. Fur, thicker in cold climates, 133. Furze, 439. G. Galapagos Archipelago, birds of, 390. ----, productions of, 398, 400. Galeopithecus, 181. Game, increase of, checked by vermin, 68. Gärtner on sterility of hybrids, 247, 255. ----, on reciprocal crosses, 258. ----, on crossed maize and verbascum, 270. ----, on comparison of hybrids and mongrels, 272. Geese, fertility when crossed, 253. ----, upland, 185. Genealogy important in classification, 425. Geoffroy St. Hilaire on balancement, 147. ---- ---- on homologous organs, 434. ---- ----, Isidore, on variability of repeated parts, 149. ---- ----, on correlation in monstrosities, 11. ---- ----, on correlation, 144. ---- ----, on variable parts being often monstrous, 155. Geographical distribution, 346. Geography, ancient, 487. Geology, future progress of, 487. ----, imperfection of the record, 279. Giraffe, tail of, 195. Glacial period, 365. Gmelin on distribution, 365. Gnathodon, fossil, 368. Godwin-Austen, Mr., on the Malay Archipelago, 300. Goethe on compensation of growth, 147. Gooseberry, grafts of, 262. Gould, Dr. A., on land-shells, 397. ----, Mr., on colours of birds, 132. ----, on birds of the Galapagos, 398. ----, on distribution of genera of birds, 404. Gourds, crossed, 270. Grafts, capacity of, 261. Grasses, varieties of, 113. Gray, Dr. Asa, on trees of United States, 100. ----, on naturalised plants in the United States, 115. ----, on rarity of intermediate varieties, 176. ----, on Alpine plants, 365. ----, Dr. J. E., on striped mule, 165. Grebe, 185. Groups, aberrant, 429. Grouse, colours of, 84. ----, red, a doubtful species, 49. Growth, compensation of, 147. ----, correlation of, in domestic products, 11. ----, correlation of, 143. H. Habit, effect of, under domestication, 11. ----, effect of, under nature, 134. ----, diversified, of same species, 183. Hair and teeth, correlated, 144. Harcourt, Mr. E. V., on the birds of Madeira, 391. Hartung, M. on boulders in the Azores, 363. Hazel-nuts, 359. Hearne on habits of bears, 184. Heath, changes in vegetation, 72. Heer, O., on plants of Madeira, 107. Helix pomatia, 397. Helosciadium, 359. Hemionus, striped, 163. Herbert, W., on struggle for existence, 62. ----, on sterility of hybrids, 249. Hermaphrodites crossing, 96. Heron eating seed, 387. Heron, Sir R., on peacocks, 89. Heusinger on white animals not poisoned by certain plants, 12. Hewitt, Mr., on sterility of first crosses, 264. Himalaya, glaciers of, 373. ----, plants of, 375. Hippeastrum, 250. Holly-trees, sexes of, 93. Hollyhock, varieties of, crossed, 271. Hooker, Dr., on trees of New Zealand, 100. {496} ----, on acclimatisation of Himalayan trees, 140. ----, on flowers of umbelliferæ, 145. ----, on glaciers of Himalaya, 373. ----, on algæ of New Zealand, 376. ----, on vegetation at the base of the Himalaya, 378. ----, on plants of Tierra del Fuego, 374, 378. ----, on Australian plants, 375, 399. ----, on relations of flora of South America, 379. ----, on flora of the Antarctic lands, 381, 399. ----, on the plants of the Galapagos, 392, 398. Hooks on bamboos, 197. ---- to seeds on islands, 392. Horner, Mr., on the antiquity of Egyptians, 18. Horns, rudimentary, 454. Horse, fossil, in La Plata, 318. Horses destroyed by flies in La Plata, 72. ----, striped, 163. ----, proportions of, when young, 444. Horticulturists, selection applied by, 32. Huber on cells of bees, 230. ----, P., on reason blended with instinct, 208. ----, on habitual nature of instincts, 208. ----, on slave-making ants, 219. ----, on Melipona domestica, 225. Humble-bees, cells of, 225. Hunter, J., on secondary sexual characters, 150. Hutton, Captain, on crossed geese, 254. Huxley, Prof., on structure of hermaphrodites, 101. ----, on embryological succession, 338. ----, on homologous organs, 438. ----, on the development of aphis, 442. Hybrids and mongrels compared, 272. Hybridism, 245. Hydra, structure of, 190. I. Ibla, 148. Icebergs transporting seeds, 363. Increase, rate of, 63. Individuals, numbers favourable to selection, 102. ----, many, whether simultaneously created, 355. Inheritance, laws of, 12. ---- at corresponding ages, 14, 86. Insects, colour of, fitted for habitations, 84. ----, sea-side, colours of, 132. ----, blind, in caves, 138. ----, luminous, 193. ----, neuter, 236. Instinct, 207. Instincts, domestic, 213. Intercrossing, advantages of, 96. Islands, oceanic, 388. Isolation favourable to selection, 104. J. Japan, productions of, 372. Java, plants of, 375. Jones, Mr. J. M., on the birds of Bermuda, 391. Jussieu on classification, 417. K. Kentucky, caves of, 137. Kerguelen-land, flora of, 381, 399. Kidney-bean, acclimatisation of, 142. Kidneys of birds, 144. Kirby on tarsi deficient in beetles, 135. Knight, Andrew, on cause of variation, 7. Kölreuter on the barberry, 98. ---- on sterility of hybrids, 246. ---- on reciprocal crosses, 258. ---- on crossed varieties of nicotiana, 271. ---- on crossing male and hermaphrodite flowers, 451. L. Lamarck on adaptive characters, 426. Land-shells, distribution of, 397. ---- of Madeira, naturalised, 403. Languages, classification of, 422. Lapse, great, of time, 282. {497} Larvæ, 440. Laurel, nectar secreted by the leaves, Laws of variation, 131. Leech, varieties of, 76. Leguminosæ, nectar secreted by glands, 92. Lepidosiren, 107, 330. Life, struggle for, 60. Lingula, Silurian, 307. Linnæus, aphorism of, 413. Lion, mane of, 88. ----, young of, striped, 439. Lobelia fulgens, 73, 98. Lobelia, sterility of crosses, 250. Loess of the Rhine, 384. Lowness of structure connected with variability, 149. Lowness, related to wide distribution, 406. Lubbock, Mr., on the nerves of coccus, 46. Lucas, Dr. P., on inheritance, 12. ----, on resemblance of child to parent, 275. Lund and Clausen on fossils of Brazil, 339. Lyell, Sir C, on the struggle for existence, 62. ----, on modern changes of the earth, 95. ----, on measure of denudation, 284. ----, on a carboniferous land-shell, 289. ----, on strata beneath Silurian system, 308. ----, on the imperfection of the geological record, 311. ----, on the appearance of species, 312. ----, on Barrande's colonies, 313. ----, on tertiary formations of Europe and North America, 323. ----, on parallelism of tertiary formations, 328. ----, on transport of seeds by icebergs, 363. ----, on great alternations of climate, 382. ----, on the distribution of fresh-water shells, 385. ----, on land-shells of Madeira, 402. Lyell and Dawson on fossilized trees in Nova Scotia, 297. M. Macleay on analogical characters, 426. Madeira, plants of, 107. ----, beetles of, wingless, 135. ----, fossil land-shells of, 339. ----, birds of, 390. Magpie tame in Norway, 212. Maize, crossed, 270. Malay Archipelago compared with Europe, 300. ----, mammals of, 395. Malpighiaceæ, 417. Mammæ, rudimentary, 451. Mammals, fossil, in secondary formation, 304. ----, insular, 394. Man, origin of races of, 199. Manatee, rudimentary nails of, 454. Marsupials of Australia, 116. ----, fossil species of, 339. Martens, M., experiment on seeds, 360. Martin, Mr. W. C., on striped mules, 165. Matteucci on the electric organs of rays, 193. Matthiola, reciprocal crosses of, 258. Means of dispersal, 356. Melipona domestica, 225. Metamorphism of oldest rocks, 308. Mice destroying bees, 74. ----, acclimatisation of, 141. Migration, bears on first appearance of fossils, 297. Miller, Prof., on the cells of bees, 226. Mirabilis, crosses of, 258. Missel-thrush, 76. Misseltoe, complex relations of, 3. Mississippi, rate of deposition at mouth, 284. Mocking-thrush of the Galapagos, 402. Modification of species, how far applicable, 483. Moles, blind, 137. Mongrels, fertility and sterility of, 268. ---- and hybrids compared, 272. {498} Monkeys, fossil, 304. Monocanthus, 424. Mons, Van, on the origin of fruit-trees, 29. Moquin-Tandon on sea-side plants, 132. Morphology, 433. Mozart, musical powers of, 209. Mud, seeds in, 386. Mules, striped, 165. Müller, Dr. F., on Alpine Australian plants, 375. Murchison, Sir R., on the formations of Russia, 290. ----, on azoic formations, 308. ----, on extinction, 317. Mustela vison, 179. Myanthus, 424. Myrmecocystus, 239. Myrmica, eyes of, 240. N. Nails, rudimentary, 454. Natural history, future progress of, 485. ---- selection, 80. ---- system, 413. Naturalisation of forms distinct from the indigenous species, 115. ---- in New Zealand, 201. Nautilus, Silurian, 307. Nectar of plants, 92. Nectaries, how formed, 92. Nelumbium luteum, 387. Nests, variation in, 211. Neuter insects, 236. Newman, Mr., on humble-bees, 74. New Zealand, productions of, not perfect, 201. ----, naturalised products of, 337. ----, fossil birds of, 339. ----, glacial action in, 373. ----, crustaceans of, 376. ----, algæ of, 376. ----, number of plants of, 389. ----, flora of, 399. Nicotiana, crossed varieties of, 271. ----, certain species very sterile, 257. Noble, Mr., on fertility of Rhododendron, 252. Nodules, phosphatic, in azoic rocks, 308. O. Oak, varieties of, 50. Onites apelles, 135. Orchis, pollen of, 193. Organs of extreme perfection, 186. ----, electric, of fishes, 192. ---- of little importance, 194. ----, homologous, 434. ----, rudiments of, and nascent, 450. Ornithorhynchus, 107, 416. Ostrich not capable of flight, 134. ----, habit of laying eggs together, 218. ----, American, two species of, 349. Otter, habits of, how acquired, 179. Ouzel, water, 185. Owen, Prof., on birds not flying, 134. ----, on vegetative repetition, 149. ----, on variable length of arms in ourang-outang, 150. ----, on the swim-bladder of fishes, 191. ----, on electric organs, 192. ----, on fossil horse of La Plata, 319. ----, on relations of ruminants and pachyderms, 329. ----, on fossil birds of New Zealand, 339. ----, on succession of types, 339. ----, on affinities of the dugong, 414. ----, on homologous organs, 434. ----, on the metamorphosis of cephalopods and spiders, 442. P. Pacific Ocean, faunas of, 348. Paley on no organ formed to give pain, 201. Pallas on the fertility of the wild stocks of domestic animals, 254. Paraguay, cattle destroyed by flies, 72. Parasites, 217. Partridge, dirt on feet, 363. Parts greatly developed, variable, 150. ----, degrees of utility of, 201. Parus major, 184. Passiflora, 251. Peaches in United States, 85. Pear, grafts of, 262. {499} Pelargonium, flowers of, 145. ----, sterility of, 251. Pelvis of women, 144. Peloria, 145. Period, glacial, 365. Petrels, habits of, 184. Phasianus, fertility of hybrids, 253. Pheasant, young, wild, 216. Philippi on tertiary species in Sicily, 312. Pictet, Prof., on groups of species suddenly appearing, 302, 305. ----, on rate of organic change, 313. ----, on continuous succession of genera, 316. ----, on close alliance of fossils in consecutive formations, 335. ----, on embryological succession, 338. Pierce, Mr., on varieties of wolves, 91. Pigeons with feathered feet and skin between toes, 12. ----, breeds described, and origin of, 20. ----, breeds of, how produced, 39, 42. ----, tumbler, not being able to get out of egg, 87. ----, reverting to blue colour, 160. ----, instinct of tumbling, 214. ----, carriers, killed by hawks, 362. ----, young of, 445. Pistil, rudimentary, 451. Plants, poisonous, not affecting certain coloured animals, 12. ----, selection applied to, 32. ----, gradual improvement of, 37. ---- not improved in barbarous countries, 38. ---- destroyed by insects, 67. ----, in midst of range, have to struggle with other plants, 77. ----, nectar of, 92. ----, fleshy, on sea-shores, 132. ----, fresh-water, distribution of, 386. ----, low in scale, widely distributed, 406. Plumage, laws of change in sexes of birds, 89. Plums in the United States, 85. Pointer dog, origin of, 35. ----, habits of, 213. Poison not affecting certain coloured animals, 12. ----, similar effect of, on animals and plants, 484. Pollen of fir-trees, 203. Poole, Col., on striped hemionus, 163. Potamogeton, 387. Prestwich, Mr., on English and French eocene formations, 328. Primrose, 49. ----, sterility of, 247. Primula, varieties of, 49. Proteolepas, 148. Proteus, 139. Psychology, future progress of, 489. Q. Quagga, striped, 165. Quince, grafts of, 262. R. Rabbit, disposition of young, 215. Races, domestic, characters of, 16. Race-horses, Arab, 35. ----, English, 356. Ramond on plants of Pyrenees, 368. Ramsay, Prof., on thickness of the British formations, 284. ----, on faults, 285. Ratio of increase, 63. Rats, supplanting each other, 76. ----, acclimatisation of, 141. ----, blind in cave, 137. Rattle-snake, 201. Reason and instinct, 208. Recapitulation, general, 459. Reciprocity of crosses, 258. Record, geological, imperfect, 279. Rengger on flies destroying cattle, 72. Reproduction, rate of, 63. Resemblance to parents in mongrels and hybrids, 273. Reversion, law of inheritance, 14. ---- in pigeons to blue colour, 160. Rhododendron, sterility of, 251. Richard, Prof., on Aspicarpa, 417. Richardson, Sir J., on structure of squirrels, 180. ----, on fishes of the southern hemisphere, 376. Robinia, grafts of, 262. {500} Rodents, blind, 137. Rudimentary organs, 450. Rudiments important for classification, 416. S. Sagaret on grafts, 262. Salmons, males fighting, and hooked jaws of, 88. Salt-water, how far injurious to seeds, 358. Saurophagus sulphuratus, 183. Schiödte on blind insects, 138. Schlegel on snakes, 144. Sea-water, how far injurious to seeds, 358. Sebright, Sir J., on crossed animals, 20. ----, on selection of pigeons, 31. Sedgwick, Prof., on groups of species suddenly appearing, 302. Seedlings destroyed by insects, 67. Seeds, nutriment in, 77. ----, winged, 146. ----, power of resisting salt-water, 358. ---- in crops and intestines of birds, 361. ---- eaten by fish, 362, 387. ---- in mud, 386. ----, hooked, on islands, 392. Selection of domestic products, 29. ----, principle not of recent origin, 33. ----, unconscious, 34. ----, natural, 80. ----, sexual, 87. ----, natural, circumstances favourable to, 102. Sexes, relations of, 87. Sexual characters variable, 156. ---- selection, 87. Sheep, Merino, their selection, 31. ----, two sub-breeds unintentionally produced, 36. ----, mountain, varieties of, 76. Shells, colours of, 132. ----, littoral, seldom embedded, 288. ----, fresh-water, dispersal of, 385 ---- of Madeira, 391. ----, land, distribution of, 397. Silene, fertility of crosses, 257. Silliman, Prof., on blind rat, 137. Skulls of young mammals, 197, 436. Slave-making instinct, 219. Smith, Col. Hamilton, on striped horses, 164. ----, Mr. Fred., on slave-making ants, 219. ----, on neuter ants, 239. ----, Mr., of Jordan Hill, on the degradation of coast-rocks, 283. Snap-dragon, 161. Somerville, Lord, on selection of sheep, 31. Sorbus, grafts of, 262. Spaniel, King Charles's breed, 35. Species, polymorphic, 46. ----, common, variable, 53. ---- in large genera variable, 54. ----, groups of, suddenly appearing, 302, 307. ---- beneath Silurian formations, 307. ---- successively appearing, 312. ---- changing simultaneously throughout the world, 322. Spencer, Lord, on increase in size of cattle, 35. Sphex, parasitic, 218. Spiders, development of, 442. Spitz-dog crossed with fox, 268. Sports in plants, 9. Sprengel, C. C, on crossing, 98. ----, on ray-florets, 145. Squirrels, gradations in structure, 180. Staffordshire, heath, changes in, 71. Stag-beetles, fighting, 88. Sterility from changed conditions of life, 9. ---- of hybrids, 246. ---- ----, laws of, 255. ---- ----, causes of, 263. ---- from unfavourable conditions, 265. ---- of certain varieties, 269. St. Helena, productions of, 390. St. Hilaire, Aug., on classification, 418. St. John, Mr., on habits of cats, 91. Sting of bee, 202. Stocks, aboriginal, of domestic animals, 18. Strata, thickness of, in Britain, 284. Stripes on horses, 163. {501} Structure, degrees of utility of, 201. Struggle for existence, 60. Succession, geological, 312. Succession of types in same areas, 338. Swallow, one species supplanting another, 76. Swim-bladder, 190. System, natural, 413. T. Tail of giraffe, 195. ---- of aquatic animals, 196. ----, rudimentary, 454. Tarsi deficient, 135. Tausch on umbelliferous flowers, 146. Teeth and hair correlated, 144. ----, embryonic, traces of, in birds, 450. ----, rudimentary, in embryonic calf, 450, 480. Tegetmeier, Mr., on cells of bees, 228, 233. Temminck on distribution aiding classification, 419. Thouin on grafts, 262. Thrush, aquatic species of, 185. ----, mocking, of the Galapagos, 402. ----, young of, spotted, 439. ----, nest of, 243. Thuret, M., on crossed fuci, 258. Thwaites, Mr., on acclimatisation, 140. Tierra del Fuego, dogs of, 215. ----, plants of, 374, 378. Timber-drift, 360. Time, lapse of, 282. Titmouse, 184. Toads on islands, 393. Tobacco, crossed varieties of, 271. Tomes, Mr., on the distribution of bats, 395. Transitions in varieties rare, 172. Trees on islands belong to peculiar orders, 392. ---- with separated sexes, 99. Trifolium pratense, 73, 94. ---- incarnatum, 94. Trigonia, 321. Trilobites, 307. ----, sudden extinction of, 321. Troglodytes, 243. Tucutucu, blind, 137. Tumbler pigeons, habits of, hereditary, 214. ----, young of, 446. Turkey-cock, brush of hair on breast, 90. Turkey, naked skin on head, 197. ----, young, wild, 216. Turnip and cabbage, analogous variations of, 159. Type, unity of, 206. Types, succession of, in same areas, 339. U. Udders enlarged by use, 11. ----, rudimentary, 451. Ulex, young leaves of, 439. Umbelliferæ, outer and inner florets of, 144. Unity of type, 206. Use, effects of, under domestication, 11. ----, effects of, in a state of nature, 134. Utility, how far important in the construction of each part, 199. V. Valenciennes on fresh-water fish, 384. Variability of mongrels and hybrids, 274. Variation under domestication, 7. ---- caused by reproductive system being affected by conditions of life, 8. ---- under nature, 44. ----, laws of, 131. Variations appear at corresponding ages, 14, 86. ----, analogous in distinct species, 159. Varieties, natural, 44. ----, struggle between, 75. ----, domestic, extinction of, 111. ----, transitional, rarity of, 172. ----, when crossed, fertile, 268. ----, when crossed, sterile, 269. ----, classification of, 423. Verbascum, sterility of, 251. ----, varieties of, crossed, 271. Verneuil, M. de, on the succession of species, 325. Viola tricolor, 73. {502} Volcanic islands, denudation of, 285. Vulture, naked skin on head, 197. W. Wading-birds, 386. Wallace, Mr., on origin of species, 2. ----, on law of geographical distribution, 355. ----, on the Malay Archipelago, 395. Wasp, sting of, 202. Water, fresh, productions of, 383. Water-hen, 185. Waterhouse, Mr., on Australian marsupials, 116. ----, on greatly developed parts being variable, 150. ----, on the cells of bees, 225. ----, on general affinities, 429. Water-ouzel, 185. Watson, Mr. H. C, on range of varieties of British plants, 58. ----, on acclimatisation, 140. ----, on flora of Azores, 363. ----, on Alpine plants, 368, 376. ----, on rarity of intermediate varieties, 176. Weald, denudation of, 285. Web of feet in water-birds, 185. West Indian islands, mammals of, 396. Westwood on species in large genera being closely allied to others, 57. ---- on the tarsi of Engidæ, 157. ---- on the antennæ of hymenopterous insects, 415. Wheat, varieties of, 113. White Mountains, flora of, 365. Wings, reduction of size, 134. ---- of insects homologous with branchiæ, 191. ----, rudimentary, in insects, 450. Wolf crossed with dog, 214. ---- of Falkland Isles, 394. Wollaston, Mr., on varieties of insects, 48. ----, on fossil varieties of land-shells in Madeira, 52. ----, on colours of insects on sea-shore, 132. ----, on wingless beetles, 135. ----, on rarity of intermediate varieties, 176. ----, on insular insects, 389. ----, on land-shells of Madeira, naturalised, 402. Wolves, varieties of, 90. Woodpecker, habits of, 184. ----, green colour of, 197. Woodward, Mr., on the duration of specific forms, 294. ----, on the continuous succession of genera, 316. ----, on the succession of types, 339. World, species changing simultaneously throughout, 322. Wrens, nest of, 243. Y. Youatt, Mr., on selection, 31. ----, on sub-breeds of sheep, 36. ----, on rudimentary horns in young cattle, 454. Z. Zebra, stripes on, 163. THE END. * * * * * LONDON: PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET, AND CHARING CROSS. * * * * * Corrections made to printed original. p. 133. "the slightest use to a being": 'slighest' in original. p. 193. "as Matteucci asserts": 'Matteucei' in original (the index correctly has Matteucci). p. 201. "deposited in the living bodies of other insects": 'depo-sisted' (across page break) in original. p. 315. "the newly-formed fantail": 'faintail' in original. p. 398. "the volcanic nature of the soil": 'volanic' in original. p. 403. "Madeira and the adjoining islet": 'Maderia' in original; and so in "from Porto Santo to Madeira". p. 442. "the same individual embryo": 'indivividual' in original. p. 458. "innumerable species, genera, and families": 'inumerable' in original. p. 490. "Inheritance which is almost implied by reproduction": 'Inheritrnce' in original. 
6882	----	This Simian World by: Clarence Day Jr. "How I hate the man who talks about the 'brute creation,' with an ugly emphasis on _brute_.... As for me, I am proud of my close kinship with other animals. I take a jealous pride in my Simian ancestry. I like to think that I was once a magnificent hairy fellow living in the trees, and that my frame has come down through geological time via sea jelly and worms and Amphioxus, Fish, Dinosaurs, and Apes. Who would exchange these for the pallid couple in the Garden of Eden?" W. N. P. Barbellion. I Last Sunday, Potter took me out driving along upper Broadway, where those long rows of tall new apartment houses were built a few years ago. It was a mild afternoon and great crowds of people were out. Sunday afternoon crowds. They were not going anywhere,--they were just strolling up and down, staring at each other, and talking. There were thousands and thousands of them. "Awful, aren't they!" said Potter. I didn't know what he meant. When he added, "Why, these crowds," I turned and asked, "Why, what about them?" I wasn't sure whether he had an idea or a headache. "Other creatures don't do it," he replied, with a discouraged expression. "Are any other beings ever found in such masses, but vermin? Aimless, staring, vacant-minded,--look at them! I can get no sense whatever of individual worth, or of value in men as a race, when I see them like this. It makes one almost despair of civilization." I thought this over for awhile, to get in touch with his attitude. I myself feel differently at different times about us human-beings: sometimes I get pretty indignant when we are attacked (for there is altogether too much abuse of us by spectator philosophers) and yet at other times I too feel like a spectator, an alien: but even then I had never felt so alien or despairing as Potter. "Let's remember," I said, "it's a simian civilization." Potter was staring disgustedly at some vaudeville sign-boards. "Yes," I said, "those for example are distinctively simian. Why should you feel disappointment at something inevitable?" And I went on to argue that it wasn't as though we were descended from eagles for instance, instead of (broadly speaking) from ape-like or monkeyish beings. Being of simian stock, we had simian traits. Our development naturally bore the marks of our origin. If we had inherited our dispositions from eagles we should have loathed vaudeville. But as cousins of the Bandarlog, we loved it. What could you expect? II If we had been made directly from clay, the way it says in the Bible, and had therefore inherited no intermediate characteristics,--if a god, or some principle of growth, had gone that way to work with us, he or it might have molded us in much more splendid forms. But considering our simian descent, it has done very well. The only people who are disappointed in us are those who still believe that clay story. Or who--unconsciously--still let it color their thinking. There certainly seems to be a power at work in the world, by virtue of which every living thing grows and develops. And it tends toward splendor. Seeds become trees, and weak little nations grow great. But the push or the force that is doing this, the yeast as it were, has to work in and on certain definite kinds of material. Because this yeast is in us there may be great and undreamed of possibilities awaiting mankind; but because of our line of descent there are also queer limitations. III In those distant invisible epochs before men existed, before even the proud missing link strutted around through the woods (little realizing how we his greatgrandsons would smile wryly at him much as our own descendants may shudder at us, ages hence) the various animals were desperately competing for power. They couldn't or didn't live as equals. Certain groups sought the headship. Many strange forgotten dynasties rose, met defiance, and fell. In the end it was our ancestors who won, and became simian kings, and bequeathed a whole planet to us--and have never been thanked for it. No monument has been raised to the memory of those first hairy conquerors; yet had they not fought well and wisely in those far-off times, some other race would have been masters, and kept us in cages, or show us for sport in the forest while they ruled the world. So Potter and I, developing this train of thought, began to imagine we had lived many ages ago, and somehow or other had alighted here from some older planet. Familiar with the ways of evolution elsewhere in the universe, we naturally should have wondered what course it would take on this earth. "Even in this out-of-the-way corner of the Cosmos," we might have reflected, "and on this tiny star, it may be of interest to consider the trend of events." We should have tried to appraise the different species as they wandered around, each with its own set of good and bad characteristics. Which group, we'd have wondered, would ever contrive to rule all the rest? And how great a development could they attain to thereafter? IV If we had landed here after the great saurians had been swept from the scene, we might first have considered the lemurs or apes. They had hands. Aesthetically viewed, the poor simians were simply grotesque; but travelers who knew other planets might have known what beauty may spring from an uncouth beginning in this magic universe. Still--those frowsy, unlovely hordes of apes and monkeys were so completely lacking in signs of kingship; they were so flighty, too, in their ways, and had so little purpose, and so much love for absurd and idle chatter, that they would have struck us, we thought, as unlikely material. Such traits, we should have reminded ourselves, persist. They are not easily left behind, even after long stages; and they form a terrible obstacle to all high advancement. V The bees or the ants might have seemed to us more promising. Their smallness of size was not necessarily too much of a handicap. They could have made poison their weapon for the subjugation of rivals. And in these orderly insects there are obviously a capacity for labor, and co-operative labor at that, which could carry them far. We all know that they have a marked genius: great gifts of their own. In a civilization of super-ants or bees, there would have been no problem of the hungry unemployed, no poverty, no unstable government, no riots, no strikes for short hours, no derision of eugenics, no thieves, perhaps no crime at all. Ants are good citizens: they place group interests first. But they carry it so far, they have few or no political rights. An ant doesn't have the vote, apparently: he just has his duties. This quality may have something to do with their having groups wars. The egotism of their individual spirits is allowed scant expression, so the egotism of the groups is extremely ferocious and active. Is this one of the reasons why ants fight so much? We have seen the same phenomenon occur in certain nations of men. And the ants commit atrocities in and after their battles that are--I wish I could truly say--inhuman. But conversely, ants are absolutely unselfish within the community. They are skilful. Ingenious. Their nests and buildings are relatively larger than man's. The scientists speak of their paved streets, vaulted halls, their hundreds of different domesticated animals, their pluck and intelligence, their individual initiative, their chaste and industrious lives. Darwin said the ant's brain was "one of the most marvelous atoms in the world, perhaps more so than the brain of man"--yes, of present-day man, who for thousands and thousands of years has had so much more chance to develop his brain.... A thoughtful observer would have weighed all these excellent qualities. When we think of these creatures as little men (which is all wrong of course) we see they have their faults. To our eyes they seem too orderly, for instance. Repressively so. Their ways are more fixed than those of the old Egyptians, and their industry is painful to think of, it's hyper-Chinese. But we must remember this is a simian comment. The instincts of the species that you and I belong to are of an opposite kind; and that makes it hard for us to judge ants fairly. But we and the ants are alike in one matter: the strong love of property. And instead of merely struggling with Nature for it, they also fight other ants. The custom of plunder seems to be a part of most of their wars. This has gone on for ages among them, and continues today. Raids, ferocious combats, and loot are part of an ant's regular life. Ant reformers, if there were any, might lay this to their property sense, and talk of abolishing property as a cure for the evil. But that would not help for long unless they could abolish the love of it. Ants seem to care even more for property than we do ourselves. We men are inclined to ease up a little when we have all we need. But it no so with ants: they can't bear to stop: they keep right on working. This means that ants do not contemplate: they heed nothing outside of their own little rounds. It is almost as though their fondness for labor had closed fast their minds. Conceivably they might have developed inquiring minds. But this would have run against their strongest instincts. The ant is knowing and wise; but he doesn't know enough to take a vacation. The worshipper of energy is too physically energetic to see that he cannot explore certain higher fields until he is still. Even if such a race had somehow achieved self-consciousness and reason, would they have been able therewith to rule their instincts, or to stop work long enough to examine themselves, or the universe, or to dream of any noble development? Probably not. Reason is seldom or never the ruler: it is the servant of instinct. It would therefore have told the ants that incessant toil was useful and good. "Toil has brought you up from the ruck of things." Reason would have plausibly said, "it's by virtue of feverish toil that you have become what you are. Being endlessly industrious is the best road--for you--to the heights." And, self-reassured, they would then have had orgies of work; and thus, by devoted exertion, have blocked their advancement. Work, and order and gain would have withered their souls. VI Let us take the great cats. They are free from this talent for slave-hood. Stately beasts like the lion have more independence of mind than the ants,--and a self-respect, we may note, unknown to primates. Or consider the leopards, with hearts that no tyrant could master. What fearless and resolute leopard-men they could have fathered! How magnificently such a civilization would have made its force tell! A race of civilized beings descended from these great cats would have been rich in hermits and solitary thinkers. The recluse would not have been stigmatized as peculiar, as he is by us simians. They would not have been a credulous people, or easily religious. False prophets and swindlers would have found few dupes. And what generals they would have made! what consummate politicians! Don't imagine them as a collection of tigers walking around on their hind-legs. They would have only been like tigers in the sense that we men are like monkeys. Their development in appearance and character would have been quite transforming. Instead of the small flat head of the tiger, they would have had clear smooth brows; and those who were not bald would have had neatly parted hair--perhaps striped. Their mouths would have been smaller and more sensitive: their faces most dignified. Where now they express chiefly savageness, they would have expressed fire and grace. They would have been courteous and suave. No vulgar crowding would have occurred on the streets of their cities. No mobs. No ignominious subway-jams. Imagine a cultivated coterie of such men and women, at a ball, dancing. How few of us humans are graceful. They would have all been Pavlowas. Like ants and bees, the cat race is nervous. Their temperaments are high-strung. They would never have become as poised or as placid as--say--super-cows. Yet they would have had less insanity, probably, than we. Monkeys' (and elephants') minds seem precariously balanced, unstable. The great cats are saner. They are intense, they would have needed sanitariums: but fewer asylums. And their asylums would have been not for weak-minded souls, but for furies. They would have been strong at slander. They would have been far more violent than we, in their hates, and they would have had fewer friendships. Yet they might not have been any poorer in real friendships than we. The real friendships among men are so rare than when they occur they are famous. Friends as loyal as Damon and Pythias were, are exceptions. Good fellowship is common, but unchanging affection is not. We like those who like us, as a rule, and dislike those who don't. Most of our ties have no better footing than that; and those who have many such ties are called warm-hearted. The super-cat-men would have rated cleanliness higher. Some of us primates have learned to keep ourselves clean, but it's no large proportion; and even the cleanest of us see no grandeur in soap-manufacturing, and we don't look to manicures and plumbers for social prestige. A feline race would have honored such occupations. J. de Courcy Tiger would have felt that nothing _but_ making soap, or being a plumber, was compatible with a high social position; and the rich Vera Pantherbilt would have deigned to dine only with manicures. None but the lowest dregs of such a race would have been lawyers spending their span of life on this mysterious earth studying the long dusty records of dead and gone quarrels. We simians naturally admire a profession full of wrangle and chatter. But that is a monkeyish way of deciding disputes, not feline. We fight best in armies, gregariously, where the risk is reduced; but we disapprove usually of murderers, and of almost all private combat. With the great cats, it would have been just the other way round. (Lions and leopards fight each other singly, not in bands, as do monkeys.) As a matter of fact, few of us delight in really serious fighting. We do love to bicker; and we box and knock each other around, to exhibit our strength; but few normal simians are keen about bloodshed and killing; we do it in war only because of patriotism, revenge, duty, glory. A feline civilization would have cared nothing for duty or glory, but they would have taken a far higher pleasure in gore. If a planet of super-cat-men could look down upon ours, they would not know which to think was the most amazing: the way we tamely live, five million or so in a city, with only a few police to keep us quiet, while we commit only one or two murders a day, and hardly have a respectable number of brawls; or the way great armies of us are trained to fight,--not liking it much, and yet doing more killing in wartime and shedding more blood than even the fiercest lion on his cruelest days. Which would perplex a gentlemanly super-cat spectator the more, our habits of wholesale slaughter in the field, or our spiritless making a fetish of "order," at home? It is fair to judge peoples by the rights they will sacrifice most for. Super-cat-men would have been outraged, had their right of personal combat been questioned. The simian submits with odd readiness to the loss of this privilege. What outrages him is to make him stop wagging his tongue. He becomes most excited and passionate about the right of free speech, even going so far in his emotion as to declare it is sacred. He looks upon other creatures pityingly because they are dumb. If one of his own children is born dumb, he counts it a tragedy. Even that mere hesitation in speech, known as stammering, he deems a misfortune. So precious to a simian is the privilege of making sounds with his tongue, that when he wishes to punish severely those men he calls criminals, he forbids them to chatter, and forces them by threats to be silent. It is felt that his punishment is entirely too cruel however and even the worst offenders should be allowed to talk part of each day. Whatever a simian does, there must always be some talking about it. He can't even make peace without a kind of chatter called a peace conference. Super-cats would not have had to "make" peace: they would have just walked off and stopped fighting. In a world of super-cat-men, I suppose there would have been fewer sailors; and people would have cared less for seaside resorts, or for swimming. Cats hate getting wet, so men descended from them might have hated it. They would have felt that even going in wading was sign of great hardihood, and only the most daring young fellows, showing off, would have done it. Among them there would have been no antivivisection societies: No Young Cat Christian Associations or Red Cross work: No Vegetarians: No early closing laws: Much more hunting and trapping: No riding to hounds; that's pure simian. Just think how it would have entranced the old-time monkeys to foresee such a game! A game where they'd all prance off on captured horses, tearing pell-mell through the woods in gay red coats, attended by yelping packs of servant-dogs. It is excellent sport--but how cats would scorn to hunt in that way! They would not have knighted explorers--they would have all been explorers. Imagine that you are strolling through a super-cat city at night. Over yonder is the business quarter, its evening shops blazing with jewels. The great stock-yards lie to the east where you hear those sad sounds: that twittering as of innumerable birds, waiting slaughter. Beyond lie the silent aquariums and the crates of fresh mice. (They raise mice instead of hens in the country, in Super-cat Land.) To the west is a beautiful but weirdly bacchanalian park, with long groves of catnip, where young super-cats have their fling, and where a few crazed catnip addicts live on till they die, unable to break off their strangely undignified orgies. And here where you stand is the sumptuous residence district. Houses with spacious grounds everywhere: no densely-packed buildings. The streets have been swept up--or lapped up--until they are spotless. Not a scrap of paper is lying around anywhere: no rubbish, no dust. Few of the pavements are left bare, as ours are, and those few are polished: the rest have deep soft velvet carpets. No footfalls are heard. There are no lights in these streets, though these people are abroad much at night. All you see are stars overhead and the glowing eyes of cat ladies, of lithe silken ladies who pass you, or of stiff-whiskered men. Beware of those men and the gleam of the split-pupiled stare. They are haughty, punctilious, inflammable: self-absorbed too, however. They will probably not even notice you; but if they do, you are lost. They take offense in a flash, abhor strangers, despise hospitality, and would think nothing of killing you or me on their way home to dinner. Follow one of them. Enter this house. Ah what splendor! No servants, though a few abject monkeys wait at the back-doors, and submissively run little errands. But of course they are never let inside: they would seem out of place. Gorgeous couches, rich colors, silken walls, an oriental magnificence. In here is the ballroom. But wait: what is this in the corner? A large triumphal statue--of a cat overcoming a dog. And look at this dining-room, its exquisite appointments, its--daintiness: faucets for hot and cold milk in the pantry, and a gold bowl of cream. Some one is entering. Hush! If I could but describe her! Languorous, slender and passionate. Sleepy eyes that see everything. An indolent purposeful step. An unimaginable grace. If you were _her_ lover, my boy, you would learn how fierce love can be, how capricious and sudden, how hostile, how ecstatic, how violent! Think what the state of the arts would have been in such cities. They would have had few comedies on their stage; no farces. Cats care little for fun. In the circus, superlative acrobats. No clowns. In drama and singing they would have surpassed us probably. Even in the state of arrested development as mere animals, in which we see cats, they wail with a passionate intensity at night in our yards. Imagine how a Caruso descended from such beings would sing. In literature they would not have begged for happy endings. They would have been personally more self-assured than we, far freer of cheap imitativeness of each other in manners and art, and hence more original in art; more clearly aware of what they really desired; not cringingly watchful of what was expected of them; less widely observant perhaps, more deeply thoughtful. Their artists would have produced less however, even though they felt more. A super-cat artist would have valued the pictures he drew for their effects on himself; he wouldn't have cared a rap whether anyone else saw them or not. He would not have bothered, usually, to give any form to his conceptions. Simply to have had the sensation would have for him been enough. But since simians love to be noticed, it does not content them to have a conception; they must wrestle with it until it takes a form in which others can see it. They doom the artistic impulse to toil with its nose to the grindstone, until their idea is expressed in a book or a statue. Are they right? I have doubts. The artistic impulse seems not to wish to produce finished work. It certainly deserts us half-way, after the idea is born; and if we go on, art is labor. With the cats, art is joy. But the dominant characteristic of this fine race is cunning. And hence I think it would have been through their craftiness, chiefly, that they would have felt the impulse to study, and the wish to advance. Craft is a cat's delight: craft they never can have too much of. So it would have been from one triumph of cunning to another that they would have marched. That would have been the greatest driving force of their civilization. This would have meant great progress in invention and science--or in some fields of science, the economic for instance. But it would have retarded them in others. Craft studies the world calculatingly, from without, instead of understandingly from within. Especially would it have cheapened the feline philosophies; for not simply how to know but how to circumvent the universe would have been their desire. Mankind's curiosity is disinterested; it seems purer by contrast. That is to say, made as we are, it seems purer to us. What we call disinterested, however, super-cats might call aimless. (Aimlessness is one of the regular simian traits.) I don't mean to be prejudiced in favor of the simian side. Curiosity may be as debasing, I grant you, as craft. And craft might turn into artifices of a kind which would be noble and fine. Just as the ignorant and fitful curiosity of some little monkey is hardly to be compared to the astronomer's magnificent search, so the craft and cunning we see in our pussies would bear small relation to the high-minded planning of some ruler of the race we are imagining. And yet--craft _is_ self-defeating in the end. Transmute it into its finest possible form, let it be as subtle and civilized as you please, as yearning and noble, as enlightened, it still sets itself over against the wholeness of things; its role is that of the part at war with the whole. Milton's Lucifer had the mind of a fine super-cat. That craft may defeat itself in the end, however, is not the real point. That doesn't explain why the lions aren't ruling the planet. The trouble is, it would defeat itself in the beginning. It would have too bitterly stressed the struggle for existence. Conflict and struggle make civilizations virile, but they do not by themselves make civilizations. Mutual aid and support are needed for that. There the felines are lacking. They do not co-operate well; they have small group-devotion. Their lordliness, their strong self-regard, and their coolness of heart, have somehow thwarted the chance of their racial progress. VII There are many other beasts that one might once have thought had a chance. Some, like horses and deer, were not bold enough; or were stupid, like buffaloes. Some had over-trustful characters, like the seals; or exploitable characters, like cows, and chickens, and sheep. Such creatures sentence themselves to be captives, by their lack of ambition. Dogs? They have more spirit. But they have lost their chance of kingship through worshipping us. The dog's finer qualities can't be praised too warmly; there is a purity about his devotion which makes mere men feel speechless: but with all love for dogs, one must grant they are vassals, not rulers. They are too parasitic--the one willing servant class of the world. And we have betrayed them by making under-simians of them. We have taught them some of our own ways of behaving, and frowned upon theirs. Loving us, they let us stop their developing in tune with their natures; and they've patiently tried ever since to adopt ways of ours. They have done it, too; but of course they can't get far: it's not their own road. Dogs have more love than integrity. They've been true to us, yes, but they haven't been true to themselves. Pigs? The pig is remarkably intelligent and brave,--but he's gross; and grossness delays one's achievement, it takes so much time. The snake too, though wise, has a way of eating himself into stupors. If super-snake-men had had banquets they would have been too vast to describe. Each little snake family could have eaten a herd of cattle at Christmas. Goats, then? Bears or turtles? Wolves, whales, crows? Each had brains and pride, and would have been glad to rule the world if they could; but each had their defects, and their weaknesses for such a position. The elephant? Ah! Evolution has had its tragedies, hasn't it, as well as its triumphs; and well should the elephant know it. He had the best chance of all. Wiser even than the lion, or the wisest of apes, his wisdom furthermore was benign where theirs was sinister. Consider his dignity, his poise and skill. He was plastic, too. He had learned to eat many foods and endure many climates. Once, some say, this race explored the globe. Their bones are found everywhere, in South America even; so the elephants' Columbus may have found some road here before ours. They are cosmopolitans, these suave and well-bred beings. They have rich emotional natures, long memories, loyalty; they are steady and sure; and not narrow, not self-absorbed, for they seem interested in everything. What was it then, that put them out of the race? Could it have been a quite natural belief that they had already won? And when they saw that they hadn't, and that the monkey-men were getting ahead, were they too great-minded and decent to exterminate their puny rivals? It may have been their tolerance and patience that betrayed them. They wait too long before they resent an imposition or insult. Just as ants are too energetic and cats too shrewd for their own highest good, so the elephants suffer from too much patience. Their exhibitions of it may seem superb,--such power and such restraint, combined, are noble,--but a quality carried to excess defeats itself. Kings who won't lift their scepters must yield in the end; and, the worst of it is, to upstarts who snatch at their crowns. I fancy the elephants would have been gentler masters than we: more live-and-let-live in allowing other species to stay here. Our way is to kill good and bad, male and female and babies, till the few last survivors lie hidden away from our guns. All species must surrender unconditionally--those are our terms--and come and live in barns alongside us; or on us, as parasites. The creatures that want to live a life of their own, we call wild. If wild, then no matter how harmless we treat them as outlaws, and those of us who are specially well brought up shoot them for fun. Some might be our friends. We don't wish it. We keep them all terrorized. When one of us conquering monkey-men enters the woods, most animals that scent him slink away, or race off in a panic. It is not that we have planned this deliberately: but they know what we're like. Race by race they have been slaughtered. Soon all will be gone. We give neither freedom nor life-room to those we defeat. If we had been as strong as the elephants, we might have been kinder. When great power comes naturally to people, it is used more urbanely. We use it as parvenus do, because that's what we are. The elephant, being born to it, is easy-going, confident, tolerant. He would have been a more humane king. A race descended from elephants would have had to build on a large scale. Imagine a crowd of huge, wrinkled, slow-moving elephant-men getting into a vast elephant omnibus. And would they have ever tried airships? The elephant is stupid when it comes to learning how to use tools. So are all other species except our own. Isn't it strange? A tool, in the most primitive sense, is any object, lying around, that can obviously be used as an instrument for this or that purpose. Many creatures use objects as _materials_, as birds use twigs for nests. But the step that no animal takes is learning freely to use things as instruments. When an elephant plucks off a branch and swishes his flanks, and thus keeps away insects, he is using a tool. But he does it only by a vague and haphazard association of ideas. If he once became a conscious user of tools he would of course go much further. We ourselves, who are so good at it now, were slow enough in beginning. Think of the long epochs that passed before it entered our heads. And all that while the contest for leadership blindly went on, without any species making use of this obvious aid. The lesson to be learned was simple: the reward was the rule of a planet. Yet only one species, our own, has ever had that much brains. It makes you wonder what other obvious lessons may still be unlearned. It is not necessarily stupid however, to fail to use tools. To use tools involves using reason, instead of sticking to instinct. Now, sticking to instinct has its disadvantages, but so has using reason. Whichever faculty you use, the other atrophies, and partly deserts you. We are trying to use both. But we still don't know which has the more value. A sudden vision comes to me of one of the first far-away ape-men who tried to use reason instead of instinct as a guide for his conduct. I imagine him, perched in his tree, torn between those two voices, wailing loudly at night by a river, in his puzzled distress. My poor far-off brother! VIII We have been considering which species was on the whole most finely equipped to be rulers, and thereafter achieve a high civilization; but that wasn't the problem. The real problem was which would _do_ it:--a different matter. To do it there was need of a species that had at least these two qualities: some quenchless desire, to urge them on and on; and also adaptability of a thousand kinds to their environment. The rhinoceros cares little for adaptability. He slogs through the world. But we! we are experts. Adaptability is what we depend on. We talk of our mastery of nature, which sounds very grand; but the fact is we respectfully adapt ourselves first, to her ways. "We attain no power over nature till we learn natural laws, and our lordship depends on the adroitness with which we learn and conform." Adroitness however is merely an ability to win; back of it there must be some spur to make us use our adroitness. Why don't we all die or give up when we're sick of the world? Because the love of life is reenforced, in most energized beings, by some longing that pushes them forward, in defeat and in darkness. All creatures wish to live, and to perpetuate their species, of course; but those two wishes alone evidently do not carry any race far. In addition to these, a race, to be great, needs some hunger, some itch, to spur it up the hard path we lately have learned to call evolution. The love of toil in the ants, and of craft in cats, are examples (imaginary or not). What other such lust could exert great driving force? With us is it curiosity? endless interest in one's environment? Many animals have some curiosity, but "some" is not enough; and in but few is it one of the master passions. By a master passion, I mean a passion that is really your master: some appetite which habitually, day in, day out, makes its subjects forget fatigue or danger, and sacrifice their ease to its gratification. That is the kind of hold that curiosity has on the monkeys. IX Imagine a prehistoric prophet observing these beings, and forecasting what kind of civilizations their descendants would build. Anyone could have foreseen certain parts of the simians' history: could have guessed that their curiosity would unlock for them, one by one, nature's doors, and--idly--bestow on them stray bits of valuable knowledge: could have pictured them spreading inquiringly all over the globe, stumbling on their inventions--and idly passing on and forgetting them. To have to learn the same thing over and over again wastes the time of a race. But this is continually necessary, with simians, because of their disorder. "Disorder," a prophet would have sighed: "that is one of their handicaps; one that they will never get rid of, whatever it costs. Having so much curiosity makes a race scatter-brained. "Yes," he would have dismally continued, "it will be a queer mixture: these simians will attain to vast stores of knowledge, in time, that is plain. But after spending centuries groping to discover some art, in after-centuries they will now and then find it's forgotten. How incredible it would seem on other planets to hear of lost arts. "There is a strong streak of triviality in them, which you don't see in cats. They won't have fine enough characters to concentrate on the things of most weight. They will talk and think far more of trifles than of what is important. Even when they are reasonably civilized, this will be so. Great discoveries sometimes will fail to be heard of, because too much else is; and many will thus disappear, and these men will not know it."[1] [1] We did rescue Mendel's from the dust heap; but perhaps it was an exception. Let me interrupt this lament to say a word for myself and my ancestors. It is easy to blame us as undiscriminating, but we are at least full of zest. And it's well to be interested, eagerly and intensely, in so many things, because there is often no knowing which may turn out important. We don't go around being interested on purpose, hoping to profit by it, but a profit may come. And anyway it is generous of us not to be too self-absorbed. Other creatures go to the other extreme to an amazing extent. They are ridiculously oblivious to what is going on. The smallest ant in the garden will ignore the largest woman who visits it. She is a huge and most dangerous super-mammoth in relation to him, and her tread shakes the earth; but he has no time to be bothered, investigating such-like phenomena. He won't even get out of her way. He has his work to do, hang it. Birds and squirrels have less of this glorious independence of spirit. They watch you closely--if you move around. But not if you keep still. In other words, they pay no more attention than they can help, even to mammoths. We of course observe everything, or try to. We could spend our lives looking on. Consider our museums for instance: they are a sign of our breed. It makes us smile to see birds, like the magpie, with a mania for this collecting--but only monkeyish beings could reverence museums as we do, and pile such heterogeneous trifles and quantities in them. Old furniture, egg-shells, watches, bits of stone.... And next door, a "menagerie." Though our victory over all other animals is now aeons old, we still bring home captives and exhibit them caged in our cities. And when a species dies out--or is crowded (by us), off the planet--we even collect the bones of the vanquished and show them like trophies. Curiosity is a valuable trait. It will make the simians learn many things. But the curiosity of a simian is as excessive as the toil of an ant. Each simian will wish to know more than his head can hold, let alone ever deal with; and those whose minds are active will wish to know everything going. It would stretch a god's skull to accomplish such an ambition, yet simians won't like to think it's beyond their powers. Even small tradesmen and clerks, no matter how thrifty, will be eager to buy costly encyclopedias, or books of all knowledge. Almost every simian family, even the dullest, will think it is due to themselves to keep all knowledge handy. Their idea of a liberal education will therefore be a great hodge-pod only. He who narrows his field and digs deep will be viewed as an alien. If more than one man in a hundred should thus dare to concentrate, the ruinous effects of being a specialist will be sadly discussed. It may make a man exceptionally useful, they will have to admit; but still they will feel badly, and fear that civilization will suffer. One of their curious educational ideas--but a natural one--will be shown in the efforts they will make to learn more than one "language." They will set their young to spending a decade or more of their lives in studying duplicate systems--whole systems--of chatter. Those who thus learn several different ways to say the same things, will command much respect, and those who learn many will be looked on with awe--by true simians. And persons without this accomplishment will be looked down on a little, and will actually feel quite apologetic about it themselves. Consider how enormously complicated a complete language must be, with its long and arbitrary vocabulary, its intricate system of sounds; the many forms that single words may take, especially if they are verbs; the rules of grammar, the sentence structure, the idioms, slang and inflections. Heavens, what a genius for tongues these simians have![1] Where another race, after the most frightful discord and pains, might have slowly constructed one language before this earth grew cold, this race will create literally hundreds, each complete in itself, and many of them with quaint little systems of writing attached. And the owners of this linguistic gift are so humble about it, they will marvel at bees, for their hives, and at beavers' mere dams. [1] You remember what Kipling says in the Jungle Books, about how disgusted the quiet animals were with the Bandarlog, because they were eternally chattering, would never keep still. Well, this is the good side of it. To return, however, to their fear of being too narrow, in going to the other extreme they will run to incredible lengths. Every civilized simian, every day of his life, in addition to whatever older facts he has picked up, will wish to know all the news of all the world. If he felt any true concern to know it, this would be rather fine of him: it would imply such a close solidarity on the part of this genus. (Such a close solidarity would seem crushing, to others; but that is another matter.) It won't be true concern, however, it will be merely a blind inherited instinct. He'll forget what he's read, the very next hour, or moment. Yet there he will faithfully sit, the ridiculous creature, reading of bombs in Spain or floods in Thibet, and especially insisting on all the news he can get of the kind our race loved when they scampered and fought in the forest, news that will stir his most primitive simian feelings,--wars, accidents, love affairs, and family quarrels. To feed himself with this largely purposeless provender, he will pay thousands of simians to be reporters of such events day and night; and they will report them on such a voluminous scale as to smother or obscure more significant news altogether. Great printed sheets will be read by every one every day; and even the laziest of this lazy race will not think it labor to perform this toil. They won't like to eat in the morning without their papers, such slaves they will be to this droll greed for knowing. They won't even think it is droll, it is so in their blood. Their swollen desire for investigating everything about them, including especially other people's affairs, will be quenchless. Few will feel that they really are "fully informed"; and all will give much of each day all their lives to the news. Books too will be used to slake this unappeasable thirst. They will actually hold books in deep reverence. Books! Bottled chatter! things that some other simian has formerly said. They will dress them in costly bindings, keep them under glass, and take an affecting pride in the number they read. Libraries --store-houses of books,--will dot their world. The destruction of one will be a crime against civilization. (Meaning, again, a simian civilization.) Well, it is an offense to be sure--a barbaric offense. But so is defacing forever a beautiful landscape; and they won't even notice that sometimes; they won't shudder anyway, the way they instinctively do at the loss of a "library." All this is inevitable and natural, and they cannot help it. There even are ways one can justify excesses like this. If their hunger for books ever seems indiscriminate to them when they themselves stop to examine it, they will have their excuses. They will argue that some bits of knowledge they once had thought futile, had later on come in most handy, in unthought of ways. True enough! For their scientists. But not for their average men: they will simply be like obstinate housekeepers who clog up their homes, preserving odd boxes and wrappings, and stray lengths of string, to exult if but one is of some trifling use ere they die. It will be in this spirit that simians will cherish their books, and pile them up everywhere into great indiscriminate mounds; and these mounds will seem signs of culture and sagacity to them. Those who know many facts will feel wise! They will despise those who don't. They will even believe, many of them, that knowledge is power. Unfortunate dupes of this saying will keep on reading, ambitiously, till they have stunned their native initiative, and made their thoughts weak; and will then wonder dazedly what in the world is the matter, and why the great power they were expecting to gain fails to appear. Again, if they ever forget what they read, they'll be worried. Those who _can_ forget--those with fresh eyes who have swept from their minds such facts as the exact month and day that their children were born, or the numbers on houses, or the names (the mere meaningless labels) of the people they meet,--will be urged to go live in sanitariums or see memory doctors! By nature their itch is rather for knowing, than for understanding or thinking. Some of them will learn to think, doubtless, and even to concentrate, but their eagerness to acquire those accomplishments will not be strong or insistent. Creatures whose mainspring is curiosity will enjoy the accumulating of facts, far more than the pausing at times to reflect on those facts. If they do not reflect on them, of course they'll be slow to find out about the ideas and relationships lying behind them; and they will be curious about those ideas; so you would suppose they'd reflect. But deep thinking is painful. It means they must channel the spready rivers of their attention. That cannot be done without discipline and drills for the mind; and they will abhor doing that; their minds will work better when they are left free to run off at tangents. Compare them in this with other species. Each has its own kind of strength. To be compelled to be so quick-minded as the simians would be torture, to cows. Cows could dwell on one idea, week by week, without trying at all; but they'd all have brain-fever in an hour at a simian tea. A super-cow people would revel in long thoughtful books on abstruse philosophical subjects, and would sit up late reading them. Most of the ambitious simians who try it--out of pride--go to sleep. The typical simian brain is supremely distractable, and it's really too jumpy by nature to endure much reflection. Therefore many more of them will be well-informed than sagacious. This will result in their knowing most things far too soon, at too early a stage of civilization to use them aright. They will learn to make valuable explosives at a stage in their growth, when they will use them not only in industries, but for killing brave men. They will devise ways to mine coal efficiently, in enormous amounts, at a stage when they won't know enough to conserve it, and will waste their few stores. They will use up a lot of it in a simian habit[1] called travel. This will consist in queer little hurried runs over the globe, to see ten thousand things in the hope of thus filling their minds. [1] Even in a wild state, the monkey is restless and does not live in lairs. Their minds will be full enough. Their intelligence will be active and keen. It will have a constant tendency however to outstrip their wisdom. Their intelligence will enable them to build great industrial systems before they have the wisdom and goodness to run them aright. They will form greater political empires than they will have strength to guide. They will endlessly quarrel about which is the best scheme of government, without stopping to realize that learning to govern comes first. (The average simian will imagine he knows without learning.) The natural result will be industrial and political wars. In a world of unmanageable structures, wild smashes must come. X Inventions will come so easily to simians (in comparison with all other creatures) and they will take such childish pleasure in monkeying around, making inventions, that their many devices will be more of a care than a comfort. In their homes a large part of their time will have to be spent keeping their numerous ingenuities in good working order--their elaborate bell-ringing arrangements, their locks and their clocks. In the field of science to be sure, this fertility in invention will lead to a long list of important and beautiful discoveries: telescopes and the calculus, radiographs, and the spectrum. Discoveries great enough, almost, to make angels of them. But here again their simian-ness will cheat them of half of their dues, for they will neglect great discoveries of the truest importance, and honor extravagantly those of less value and splendor if only they cater especially to simian traits. To consider examples: A discovery that helps them to talk, just to talk, more and more, will be hailed by these beings as one of the highest of triumphs. Talking to each other over wires will come in this class. The lightning when harnessed and tamed will be made to trot round, conveying the most trivial cacklings all day and night. Huge seas of talk of every sort and kind, in print, speech, and writing, will roll unceasingly over their civilized realms, involving an unbelievable waste in labor and time, and sapping the intelligence talk is supposed to upbuild. In a simian civilization, great halls will be erected for lectures, and great throngs will actually pay to go inside at night to hear some self-satisfied talk-maker chatter for hours. Almost any subject will do for a lecture, or talk; yet very few subjects will be counted important enough for the average man to do any _thinking_ on them, off by himself. In their futurist books they will dream of an even worse state, a more dreadful indulgence in communication than the one just described. This they'll hope to achieve by a system called mental telepathy. They will long to communicate wordlessly, mind impinging on mind, until all their minds are awash with messages every moment, and withdrawal from the stream is impossible anywhere on earth. This will foster the brotherhood of man. (Conglomerateness being their ideal.) Super-cats would have invented more barriers instead of more channels. Discoveries in surgery and medicine will also be over-praised. The reason will be that the race will so need these discoveries. Unlike the great cats, simians tend to undervalue the body. Having less self-respect, less proper regard for their egos, they care less than the cats do for the casing of the ego,--the body. The more civilized they grow the more they will let their bodies deteriorate. They will let their shoulders stoop, their lungs shrink, and their stomachs grow fat. No other species will be quite so deformed and distorted. Athletics they will watch, yes, but on the whole sparingly practise. Their snuffy old scholars will even be proud to decry them. Where once the simians swung high through forests, or scampered like deer, their descendants will plod around farms, or mince along city streets, moving constrictedly, slowly, their litheness half gone. They will think of Nature as "something to go out and look at." They will try to live wholly apart from her and forget they're her sons. Forget? They will even deny it, and declare themselves sons of God. In spite of her wonders they will regard Nature as somehow too humble to be the true parent of such prominent people as simians. They will lose all respect for the dignity of fair Mother Earth, and whisper to each other she is an evil and indecent old person. They will snatch at her gifts, pry irreverently into her mysteries, and ignore half the warnings they get from her about how to live. Ailments of every kind will abound among such folk, inevitably, and they will resort to extraordinary expedients in their search for relief. Although squeamish as a race about inflicting much pain in cold blood, they will systematically infect other animals with their own rank diseases, or cut out other animals' organs, or kill and dissect them, hoping thus to learn how to offset their neglect of themselves. Conditions among them will be such that this will really be necessary. Few besides impractical sentimentalists will therefore oppose it. But the idea will be to gain health by legerdemain, by a trick, instead of by taking the trouble to live healthy lives. Strange barrack-like buildings called hospitals will stand in their cities, where their trick-men, the surgeons, will slice them right open when ill; and thousands of zealous young pharmacists will mix little drugs, which thousands of wise-looking simians will firmly prescribe. Each generation will change its mind as to these drugs, and laugh at all former opinions; but each will use some of them, and each will feel assured that in this respect they know the last word. And, in obstinate blindness, this people will wag their poor heads, and attribute their diseases not to simian-ness but to civilization. The advantages that any man or race has, can sometimes be handicaps. Having hands, which so aids a race, for instance, can also be harmful. The simians will do so many things with their hands, it will be bad for their bodies. Instead of roaming far and wide over the country, getting vigorous exercise, they will use their hands to catch and tame horses, build carriages, motors, and then when they want a good outing they will "go for a ride," with their bodies slumped down, limp and sluggish, and losing their spring. Then too their brains will do harm, and great harm, to their bodies. The brain will give them such an advantage over all other animals that they will insensibly be led to rely too much on it, to give it too free a rein, and to find the mirrors in it too fascinating. This organ, this outgrowth, this new part of them, will grow over-active, and its many fears and fancies will naturally injure the body. The interadjustment is delicate and intimate, the strain is continuous. When the brain fails to act with the body, or, worse, works against it, the body will sicken no matter what cures doctors try. As in bodily self-respect, so in racial self-respect, they'll be wanting. They will have plenty of racial pride and prejudice, but that is not the same thing. That will make them angry when simians of one color mate with those of another. But a general deterioration in physique will cause much less excitement. They will _talk_ about improving the race--they will talk about everything--but they won't use their chances to _do_ it. Whenever a new discovery makes life less hard, for example, these heedless beings will seldom preserve this advantage, or use their new wealth to take more time thereafter for thought, or to gain health and strength or do anything else to make the race better. Instead, they will use the new ease just to increase in numbers; and they will keep on at this until misery once more has checked them. Life will then be as hard as ever, naturally, and the chance will be gone. They will have a proverb, "The poor ye have always with you,"--said by one who knew simians. Their ingenious minds will have an answer to this. They will argue it is well that life should be Spartan and hard, because of the discipline and its strengthening effects on the character. But the good effects of this sort of discipline will be mixed with sad wreckage. And only creatures incapable of disciplining themselves could thus argue. It is an odd expedient to get yourself into trouble just for discipline's sake. The fact is, however, the argument won't be sincere. When their nations grow so over-populous and their families so large it means misery, that will not be a sign of their having felt ready for discipline. It will be a sign of their not having practised it in their sexual lives. XI The simians are always being stirred by desire and passion. It constantly excites them, constantly runs through their minds. Wild or tame, primitive or cultured, this is a brand of the breed. Other species have times and seasons for sexual matters, but the simian-folk are thus preoccupied all the year round. This super-abundance of desire is not necessarily good or bad, of itself. But to shape it for the best it will have to be studied--and faced. This they will not do. Some of them won't like to study it, deeming it bad--deeming it bad yet yielding constantly to it. Others will hesitate because they will deem it so sacred, or will secretly fear that study might show them it ought to be curbed. Meantime, this part of their nature will be coloring all their activities. It will beautify their arts, and erotically confuse their religions. It will lend a little interest to even their dull social functions. It will keep alive degrading social evils in all their great towns. Through these latter evils, too, their politics will be corrupted; especially their best and most democratic attempts at self-government. Self-government works best among those who have learned to self-govern. In the far distant ages that lie before us what will be the result of this constant preoccupation with desire? Will it kill us or save us? Will this trait and our insatiable curiosity interact on each other? That might further eugenics. That might give us a better chance to breed finely than all other species. We already owe a great deal to passion: more than men ever realize. Wasn't it Darwin who once even risked the conjecture that the vocal organs themselves were developed for sexual purposes, the object being to call or charm one's mate. Hence--perhaps--only animals that were continuously concerned with their matings would be at all likely to form an elaborate language. And without an elaborate language, growth is apt to be slow. If we owe this to passion, what follows? Does it mean, for example, that the more different mates that each simian once learned to charm, the more rapidly language, and with it civilization, advanced? XII A doctor, who was making a study of monkeys, once told me that he was trying experiments that bore on the polygamy question. He had a young monkey named Jack who had mated with a female named Jill; and in another cage another newly-wedded pair, Arabella and Archer. Each pair seemed absorbed in each other, and devoted and happy. They even bugged each other at mealtime and exchanged bits of food. After a time their transports grew less fiery, and their affections less fixed. Archer got a bit bored. He was decent about it, though, and when Arabella cuddled beside him he would more or less perfunctorily embrace her. But when he forgot, she grew cross. The same thing occurred a little later in the Jack and Jill cage, only there it was Jill who became a little tired of Jack. Soon each pair was quarreling. They usually made up, pretty soon, and started loving again. But it petered out; each time more quickly. Meanwhile the two families had become interested in watching each other. When Jill had repulsed Jack, and he had moped about it awhile, he would begin staring at Arabella, over opposite, and trying to attract her attention. This got Jack in trouble all around. Arabella indignantly made faces at him and then turned her back; and as for Jill, she grew furious, and tore out his fur. But in the next stage, they even stopped hating each other. Each pair grew indifferent. Then the doctor put Jack in with Arabella, and Archer with Jill. Arabella promptly yielded to Jack. New devotion. More transports. Jill and Archer were shocked. Jill clung to the bars of her cage, quivering, and screaming remonstrance; and even blase Archer chattered angrily at some of the scenes. Then the doctor hung curtains between the cages to shut out the view. Jill and Archer, left to each other, grew interested. They soon were inseparable. The four monkeys, thus re-distributed, were now happy once more, and full of new liveliness and spirit. But before very long, each pair quarreled--and made up--and quarreled--and then grew indifferent, and had cynical thoughts about life. At this point, the doctor put them back with their original mates. And--they met with a rush! Gave cries of recognition and joy, like faithful souls re-united. And when they were tired, they affectionately curled up together; and hugged each other even at mealtime, and exchanged bits of food. This was as far as the doctor had gotten, at the time that I met him; and as I have lost touch with him since, I don't know how things were afterward. His theory at the time was, that variety was good for fidelity. "So how can _we_ help being that way? It's in the blood," he concluded. "Some creatures, such as wolves, are more serious; or perhaps more cold-blooded. Never mate but once. Well--we're not wolves. We can't make wolves our models. If we want to know how to behave, according to the way nature made us, if we want to know what is good for our instincts, we must study the monkeys." To be sure, these particular monkeys were living in idleness. This corresponds to living in high social circles with us, where men do not have to work, and lack some of the common incentives to home-building. The experiment was not conclusive. Still, even in low social circles-- XIII Are we or are we not simians? It is no use for any man to try to think anything else out until he has decided first of all where he stands on that question. It is not only in love affairs: let us lay all that aside for the moment. It is in ethics, economics, art, education, philosophy, what-not. If we are fallen angels, we should go this road: if we are super-apes, that. "Our problem is not to discover what we ought to do if we were different, but what we ought to do, being what we are. There is no end to the beings we can imagine different from ourselves; but they do not exist," and we cannot be sure they would be better than we if they did. For, when we imagine them, we must imagine their entire environment; they would have to be a part of some whole that does not now exist. And that new whole, that new reality, being merely a figment of our little minds, "would probably be inferior to the reality that is. For there is this to be said in favor of reality: that we have nothing to compare it with. Our fantasies are always incomplete, because they are fantasies. And reality is complete. We cannot compare their incompleteness with its completeness."[1] [1] From an anonymous article entitled "Tolstoy and Russia" in the London Times, Sept. 26,1918. Too many moralists begin with a dislike of reality: a dislike of men as they are. They are free to dislike them--but not at the same time to be moralists. Their feeling leads them to ignore the obligation which should rest on all teachers, "to discover the best that man can do, not to set impossibilities before him and tell him that if he does not perform them he is damned." Man is moldable; very; and it is desirable that he should aspire. But he is apt to be hasty about accepting any and all general ideals without figuring out whether they are suitable for simian use. One result of his habit of swallowing whole most of the ideals that occur to him, is that he has swallowed a number that strongly conflict. Any ideal whatever strains our digestions if it is hard to assimilate: but when two at once act on us in different ways, it is unbearable. In such a case, the poets will prefer the ideal that's idealest: the hard-headed instinctively choose the one adapted to simians. Whenever this is argued, extremists spring up on each side. One extremist will say that being mere simians we cannot transcend much, and will seem to think that having limitations we should preserve them forever. The other will declare that we are not merely simians, never were just plain animals; or, if we were, souls were somehow smuggled in to us, since which time we have been different. We have all been perfect at heart since that date, equipped with beautiful spirits, which only a strange perverse obstinacy leads us to soil. What this obstinacy is, is the problem that confronts theologians. They won't think of it as simian-ness; they call it original sin. They regard it as the voice of some devil, and say good men should not listen to it. The scientists say it isn't a devil, it is part of our nature, which should of course be civilized and guided, but should not be stamped out. (It might mutilate us dangerously to become under-simianized. Look at Mrs. Humphry Ward and George Washington. Worthy souls, but no flavor.) In every field of thought then, two schools appear, that are divided on this: Must we forever be at heart high-grade simians? Or are we at heart something else? For example, in education, we have in the main two great systems. One depends upon discipline. The other on exciting the interest. The teacher who does not recognize or allow for our simian nature, keeps little children at work for long periods at dull and dry tasks. Without some such discipline, he fears that his boys will lack strength. The other system believes they will learn more when their interest is roused; and when their minds, which are mobile by nature, are allowed to keep moving. Or in politics: the best government for simians seems to be based on a parliament: a talk-room, where endless vague thoughts can be warmly expressed. This is the natural child of those primeval sessions that gave pleasure to apes. It is neither an ideal nor a rational arrangement, of course. Small executive committees would be better. But not if we are simians. Or in industry: Why do factory workers produce more in eight hours a day than in ten? It is absurd. Super-sheep could not do it. But that is the way men are made. To preach to such beings about the dignity of labor is futile. The dignity of labor is not a simian conception at all. True simians hate to have to work steadily: they call it grind and confinement. They are always ready to pity the toilers who are condemned to this fate, and to congratulate those who escape it, or who can do something else. When they see some performer in spangles risk his life, at a circus, swinging around on trapezes, high up in the air, and when they are told he must do it daily, do they pity _him?_ No! Super-elephants would say, and quite properly, "What a horrible life!" But it naturally seems stimulating to simians. Boys envy the fellow. On the other hand whenever we are told about factory life, we instinctively shudder to think of enduring such evils. We see some old work-man, filling cans with a whirring machine; and we hear the humanitarians telling us, indignant and grieving, that he actually must stand in that nice, warm, dry room every day, safe from storms and wild beasts, and with nothing to do but fill cans; and at once we groan: "How deadly! What monotonous toil! Shorten his hours!" His work would seem blissful to super-spiders,--but to us it's intolerable. "Grind and confinement?" That's the strong monkey-blood in our veins. Our monkey-blood is also apparent in our judgments of crime. If a crime is committed on impulse, we partly forgive it. Why? Because, being simians, with a weakness for yielding to impulses, we like to excuse ourselves by feeling not accountable for them. Elephants would have probably taken an opposite stand. They aren't creatures of impulse, and would be shocked at crimes due to such causes; their fault is the opposite one of pondering too long over injuries, and becoming vindictive in the end, out of all due proportion. If a young super-elephant were to murder another on impulse, they would consider him a dangerous character and string him right up. But if he could prove that he had long thought of doing it, they would tend to forgive him. "Poor fellow, he brooded," they would say. "That's upsetting to any one." As to modesty and decency, if we are simians we have done well, considering: but if we are something else--fallen angels--we have indeed fallen far. Not being modest by instinct we invent artificial ideals, which are doubtless well-meaning but are inherently of course second-rate, so that even at our best we smell prudish. And as for our worst, when we as we say let ourselves go, we dirty the life-force unspeakably, with chuckles and leers. But a race so indecent by nature as the simians are would naturally have a hard time behaving as though they were not: and the strain of pretending that their thoughts were all pretty and sweet, would naturally send them to smutty extremes for relief. The standards of purity we have adopted are far too strict--for simians. XIV We were speaking a while ago of the fertility with which simians breed. This is partly due to the constant love interest they take in each other, but it is also reenforced by their reliance on numbers. That reliance will be deep, since, to their numbers, they will owe much success. It will be thus that they will drive out other species, and garrison the globe. Such a race would naturally come to esteem fertility. It will seem profane not to. As time goes on, however, the advantage of numbers will end; and in their higher stages, large numbers will be a great drawback. The resources of a planet are limited, at each stage of the arts. Also, there is only a limited space on a planet. Yet it will come hard to them to think of ever checking their increase. They will bring more young into existence than they can either keep well or feed. The earth will be covered with them everywhere, as far as eye can see. North and south, east and west, there will always be simians huddling. Their cities will be far more distressing than cities of vermin,--for vermin are healthy and calm and successful in life. Ah, those masses of people--unintelligent, superstitious, uncivilized! What a dismal drain they will be on the race's strength! Not merely will they lessen its ultimate chance of achievement; their hardships will always distress and preoccupy minds,--fine, generous minds,--that might have done great things if free: that might have done something constructive at least, for their era, instead of being burned out attacking mere anodyne-problems. Nature will do what it can to lessen the strain, providing an appropriate remedy for their bad behavior in plagues. Many epochs will pass before the simians will learn or dare to control them--for they won't think they can, any more than they dare control propagation. They will reverently call their propagation and plagues "acts of God." When they get tired of reverence and stop their plagues, it will be too soon. Their inventiveness will be--as usual--ahead of their wisdom; and they will unfortunately end the good effects of plagues (as a check) before they are advanced enough to keep down their numbers themselves. Meanwhile, when, owing to the pressure of other desires, any group of primates does happen to become less prolific, they will feel ashamed, talk of race suicide, and call themselves decadent. And they will often be right: for though some regulation of the birth-rate is an obvious good, and its diminution often desirable in any planet's history, yet among simians it will be apt to come from second-rate motives. Greed, selfishness or fear-thoughts will be the incentives, the bribes. Contrivances, rather than continence, will be the method. How audacious, and how disconcerting to Nature, to baffle her thus! Even into her shrine they must thrust their bold paws to control her. Another race viewing them in the garlanded chambers of love, unpacking their singular devices, might think them grotesque: but the busy little simians will be blind to such quaint incongruities. Still, there is a great gift that their excess of passion will bestow on this race: it will give them romance. It will teach them what little they ever will learn about love. Other animals have little romance: there is none in the rut: that seasonal madness that drives them to mate with perhaps the first comer. But the simians will attain to a fine descrimination in love, and this will be their path to the only spiritual heights they can reach. For, in love, their inmost selves will draw near, in the silence of truth; learning little by little what the deepest sincerity means, and what clean hearts and minds and what crystal-clear sight it demands. Such intercommunication of spirit with spirit is at the beginning of all true understanding. It is the beginning of silent cosmic wisdom: it may lead to knowing the ways of that power called God. XV Not content with the whole of a planet and themselves too, to study, this race's children will also study the heavens. How few kinds of creatures would ever have felt that impulse, and yet how natural it will seem to these! How boundless and magnificent is the curiosity of these tiny beings, who sit and peer out at the night from their small whirling globe, considering deeply the huge cold seas of space, and learning with wonderful skill to measure the stars. In studies so vast, however, they are tested to the core. In these great journeys the traveller must pay dear for his flaws. For it always is when you most finely are exerting your strength that every weakness you have most tells against you. One weakness of the primates is the character of their self-consciousness. This useful faculty, that can probe so-deep, has one naive defect--it relies too readily on its own findings. It doesn't suspect enough its own unconfessed predilections. It assumes that it can be completely impartial--but isn't. To instance an obvious way in which it will betray them: beings that are intensely self-conscious and aware of their selves, will also instinctively feel that their universe is. What active principle animates the world, they will ask. A great blind force? It is possible. But they will recoil from admitting any such possibility. A self-aware purposeful force then? That is better! (More simian.) "A blind force can't have been the creator of all. It's unthinkable." Any theory _their_ brains find "unthinkable" cannot be true. (This is not to argue that it really is a blind force--or the opposite. It is merely an instance of how little impartial they are.) A second typical weakness of this race will come from their fears. They are not either self-sufficing or gallant enough to travel great roads without cringing,--clear-eyed, unafraid. They are finely made, but not nobly made,--in that sense. They will therefore have a too urgent need of religion. Few primates have the courage to face--alone--the still inner mysteries: Infinity, Space and Time. They will think it too terrible, they will feel it would turn them to water, to live through unearthly moments of vision without creeds or beliefs. So they'll get beliefs first. Ah, poor creatures! The cart before the horse! Ah, the blasphemy (pitiful!) of their seeking high spiritual temples, with god-maps or bibles about them, made below in advance! Think of their entering into the presence of Truth, declaring so loudly and boldly they know her already, yet far from willing to stand or fall by her flames--to rise like a phoenix or die as an honorable cinder!--but creeping in, clad in their queer blindfolded beliefs, designed to shield them from her stern, bright tests! Think of Truth sadly--or merrily--eyeing such worms! XVI Imagine you are watching the Bandarlog at play in the forest. As you behold them and comprehend their natures, now hugely brave and boastful, now full of dread, the most weakly emotional of any intelligent species, ever trying to attract the notice of some greater animal, not happy indeed unless noticed,--is it not plain they are bound to invent things called gods? Don't think for the moment of whether there are gods or not; think of how sure these beings would be to invent them. (Not wait to find them.) Having small self-reliance they can not bear to face life alone. With no self-sufficingness, they must have the countenance of others. It is these pressing needs that will hurry the primates to build, out of each shred of truth they can possibly twist to their purpose, and out of imaginings that will impress them because they are vast, deity after deity to prop up their souls. What a strange company they will be, these gods, in their day, each of them an old bearded simian up in the sky, who begins by fishing the universe out of a void, like a conjurer taking a rabbit out of a hat. (A hat which, if it resembled a void, wasn't there.) And after creating enormous suns and spheres, and filling the farthest heavens with vaster stars, one god will turn back and long for the smell of roast flesh, another will call desert tribes to "holy" wars, and a third will grieve about divorce or dancing. All gods that any groups of simians ever conceive of, from the woodenest little idol in the forest to the mightiest Spirit, no matter how much they may differ, will have one trait in common: a readiness to drop any cosmic affair at short notice, focus their minds on the far-away pellet called Earth, and become immediately wholly concerned, aye, engrossed, with any individual worshipper's woes or desires,--a readiness to notice a fellow when he is going to bed. This will bring indescribable comfort to simian hearts; and a god that neglects this duty won't last very long, no matter how competent he may be in other respects. But one must reciprocate. For the maker of the Cosmos, as they see him, wants noticing too; he is fond of the deference and attention that simians pay him, and naturally he will be angry if it is withheld;--or if he is not, it will be most magnanimous of him. Hence prayers and hymns. Hence queer vague attempts at communing with this noble kinsman. To desire communion with gods is a lofty desire, but hard to attain through an ignobly definite creed. Dealing with the highest, most wordless states of being, the simians will attempt to conceive them in material form. They will have beliefs, for example, as to the furnishings and occupations in heaven. And why? Why, to help men to have religious conceptions without themselves being seers,--which in any true sense of "religious" is an impossible plan. In their efforts to be concrete they will make their creeds amusingly simian. Consider the simian amorousness of Jupiter, and the brawls on Olympus. Again, in the old Jewish Bible, what tempts the first pair? The Tree of Knowledge, of course. It appealed to the curiosity of their nature, and who could control _that!_ And Satan in the Bible is distinctly a simian's devil. The snake, it is known, is the animal monkeys most dread. Hence when men give their devil a definite form they make him a snake. A race of super-chickens would have pictured their devil a hawk. XVII What are the handicaps this race will have in building religions? The greatest is this: they have such small psychic powers. The over-activity of their minds will choke the birth of such powers, or dull them. The race will be less in touch with Nature, some day, than its dogs. It will substitute the compass for its once innate sense of direction. It will lose its gifts of natural intuition, premonition, and rest, by encouraging its use of the mind to be cheaply incessant. This lack of psychic power will cheat them of insight and poise; for minds that are wandering and active, not receptive and still, can seldom or never be hushed to a warm inner peace. One service these restless minds however will do: they eventually will uncritically through the religions they themselves have invented. But ages will be thrown away in repeating this process. A simian creed will not be very hard thus to pierce. When forming a religion, they will be in far too much haste, to wait to apply a strict test to their holy men's visions. Furthermore they will have so few visions, that any will awe them; so naturally they will accept any vision as valid. Then their rapid and fertile inventiveness will come into play, and spin the wildest creeds from each vision living dust ever dreamed. They will next expect everybody to believe whatever a few men have seen, on the slippery ground that if you simply try believing it, you will then feel it's true. Such religions are vicarious; their prophets alone will see God, and the rest will be supposed to be introduced to him by the prophets. These "believers" will have no white insight at all of their own. Now, a second-hand believer who is warmed at one remove--if at all --by the breath of the spirit, will want to have exact definitions in the beliefs he accepts. Not having had a vision to go by, he needs plain commandments. He will always try to crystallize creeds. And that, plainly, is fatal. For as time goes on, new and remoter aspects of truth are discovered, which can seldom or never be fitted into creeds that are changeless. Over and over again, this will be the process: A spiritual personality will be born; see new truth; and be killed. His new truth not only will not fit into too rigid creeds, but whatever false finality is in them it must contradict. So, the seer will be killed. His truth being mighty, however, it will kill the creeds too. There will then be nothing left to believe in--except the dead seer. For a few generations he may then be understandingly honored. But his priests will feel that is not enough: he must be honored uncritically: so uncritically that, whatever his message, it must be deemed the Whole Truth. Some of his message they themselves will have garbled; and it was not, at best, final; but still it will be made into a fixed creed and given his name. Truth will be given his name. All men who thereafter seek truth must find only his kind, else they won't be his "followers." (To be his co-seekers won't do.) Priests will always hate any new seers who seek further for truth. Their feeling will be that their seer found it, and thus ended all that. Just believe what he says. The job's over. No more truth need be sought. It's a comforting thing to believe cosmic search nicely settled. Thus the mold will be hardened. So new truths, when they come, can but break it. Then men will feel distraught and disillusioned, and civilizations will fall. Thus each cycle will run. So long as men interwine falsehoods with every seer's visions, both perish, and every civilization that is built on them must perish too. XVIII If men can ever learn to accept all their truths as not final, and if they can ever learn to build on something better than dogma, they may not be found saying, discouragedly, every once in so often, that every civilization carries in it the seeds of decay. It will carry such seeds with great certainty, though, when they're put there, by the very race, too, that will later deplore the results. Why shouldn't creeds totter when they are jerry-built creeds? On stars where creeds come late in the life of a race; where they spring from the riper, not cruder, reactions of spirit; where they grow out of nobly developed psychic powers that have put their possessors in tune with cosmic music; and where no cheap hallucinations discredit their truths; they perhaps run a finer, more beautiful course than the simians', and open the eyes of the soul to far loftier visions. XIX It has always been a serious matter for men when a civilization decayed. But it may at some future day prove far more serious still. Our hold on the planet is not absolute. Our descendants may lose it. Germs may do them out of it. A chestnut fungus springs up, defies us, and kills all our chestnuts. The boll weevil very nearly baffles us. The fly seems unconquerable. Only a strong civilization, when such foes are about, can preserve us. And our present efforts to cope with such beings are fumbling and slow. We haven't the habit of candidly facing this danger. We read our biological history but we don't take it in. We blandly assume we were always "intended" to rule, and that no other outcome could even be considered by Nature. This is one of the remnants of ignorance certain religions have left: but it's odd that men who don't believe in Easter should still believe this. For the facts are of course this is a hard and precarious world, where every mistake and infirmity must be paid for in full. If mankind ever is swept aside as a failure however, what a brilliant and enterprising failure he at least will have been. I felt this with a kind of warm suddenness only today, as I finished these dreamings and drove through the gates of the park. I had been shutting my modern surroundings out of my thoughts, so completely, and living as it were in the wild world of ages ago, that when I let myself come back suddenly to the twentieth century, and stare at the park and the people, the change was tremendous. All around me were the well-dressed descendants of primitive animals, whizzing about in bright motors, past tall, soaring buildings. What gifted, energetic achievers they suddenly seemed! I thought of a photograph I had once seen, of a ship being torpedoed. There it was, the huge, finely made structure, awash in the sea, with tiny black spots hanging on to its side--crew and passengers. The great ship, even while sinking, was so mighty, and those atoms so helpless. Yet, it was those tiny beings that had created that ship. They had planned it and built it and guided its bulk through the waves. They had also invented a torpedo that could rend it asunder. It is possible that our race may be an accident, in a meaningless universe, living its brief life uncared-for, on this dark, cooling star: but even so--and all the more--what marvelous creatures we are! What fairy story, what tale from the Arabian Nights of the jinns, is a hundredth part as wonderful as this true fairy story of simians! It is so much more heartening, too, than the tales we invent. A universe capable of giving birth to many such accidents is--blind or not--a good world to live in, a promising universe. And if there are no other such accidents, if we stand alone, if all the uncountable armies of planets are empty, or peopled by animals only, with no keys to thought, then we have done something so mighty, what may it not lead to! What powers may we not develop before the Sun dies! We once thought we lived on God's footstool: it may be a throne. This is no world for pessimists. An amoeba on the beach, blind and helpless, a mere bit of pulp,--that amoeba has grandsons today who read Kant and play symphonies. Will those grandsons in turn have descendants who will sail through the void, discover the foci of forces, the means to control them, and learn how to marshal the planets and grapple with space? Would it after all be any more startling than our rise from the slime? No sensible amoeba would have ever believed for a minute that any of his most remote children would build and run dynamos. Few sensible men of today stop to feel, in their hearts, that we live in the very same world where that miracle happened. This world, and our racial adventure, are magical still. XX Yet although for high-spirited marchers the march is sufficient, there still is that other way of looking at it that we dare not forget. Our adventure may satisfy _us:_ does it satisfy Nature? She is letting us camp for awhile here among the wrecked graveyards of mightier dynasties, not one of which met her tests. Their bones are the message the epochs she murdered have left us: we have learned to decipher their sickening warning at last. Yes, and even if we are permitted to have a long reign, and are not laid away with the failures, are we a success? We need so much spiritual insight, and we have so little. Our telescopes may some day disclose to us the hills of Arcturus, but how will that help us if we cannot find the soul of the world? Is that soul alive and loving? or cruel? or callous? or dead? We have no sure vision. Hopes, guesses, beliefs--that is all. There are sounds we are deaf to, there are strange sights invisible to us. There are whole realms of splendor, it may be, of which we are heedless; and which we are as blind to as ants to the call of the sea. Life is enormously flexible--look at all that we've done to our dogs,--but we carry our hairy past with us wherever we go. The wise St. Bernards and the selfish toy lap-dogs are brothers, and some things are possible for them and others are not. So with us. There are definite limits to simian civilizations, due in part to some primitive traits that help keep us alive, and in part to the mere fact that every being has to be something, and when one is a simian one is not also everything else. Our main-springs are fixed, and our principal traits are deep-rooted. We cannot now re-live the ages whose imprint we bear. We have but to look back on our past to have hope in our future: but--it will be only _our_ future, not some other race's. We shall win our own triumphs, yet know that they would have been different, had we cared above all for creativeness, beauty, or love. So we run about, busy and active, marooned on this star, always violently struggling, yet with no clearly seen goal before us. Men, animals, insects--what tribe of us asks any object, except to keep trying to satisfy its own master appetite? If the ants were earth's lords they would make no more use of their lordship than to learn and enforce every possible method of foiling. Cats would spend their span of life, say, trying new kinds of guile. And we, who crave so much to know, crave so little but knowing. Some of us wish to know Nature most; those are the scientists. Others, the saints and philosophers, wish to know God. Both are alike in their hearts, yes, in spite of their quarrels. Both seek to assuage to no end, the old simian thirst. If we wanted to _be_ Gods--but ah, can we grasp that ambition? 
2009	----	THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION; or, the PRESERVATION OF FAVOURED RACES IN THE STRUGGLE FOR LIFE. By Charles Darwin, M.A., F.R.S., Author of "The Descent of Man," etc., etc. Sixth London Edition, with all Additions and Corrections. The 6th Edition is often considered the definitive edition. Also see Project Gutenberg Etext #1228 for the First Edition. "But with regard to the material world, we can at least go so far as this--we can perceive that events are brought about not by insulated interpositions of Divine power, exerted in each particular case, but by the establishment of general laws."--Whewell: "Bridgewater Treatise". "The only distinct meaning of the word 'natural' is STATED, FIXED or SETTLED; since what is natural as much requires and presupposes an intelligent agent to render it so, i.e., to effect it continually or at stated times, as what is supernatural or miraculous does to effect it for once."--Butler: "Analogy of Revealed Religion". "To conclude, therefore, let no man out of a weak conceit of sobriety, or an ill-applied moderation, think or maintain, that a man can search too far or be too well studied in the book of God's word, or in the book of God's works; divinity or philosophy; but rather let men endeavour an endless progress or proficience in both."--Bacon: "Advancement of Learning". AN HISTORICAL SKETCH OF THE PROGRESS OF OPINION ON THE ORIGIN OF SPECIES, PREVIOUSLY TO THE PUBLICATION OF THE FIRST EDITION OF THIS WORK. I will here give a brief sketch of the progress of opinion on the Origin of Species. Until recently the great majority of naturalists believed that species were immutable productions, and had been separately created. This view has been ably maintained by many authors. Some few naturalists, on the other hand, have believed that species undergo modification, and that the existing forms of life are the descendants by true generation of pre existing forms. Passing over allusions to the subject in the classical writers (Aristotle, in his "Physicae Auscultationes" (lib.2, cap.8, s.2), after remarking that rain does not fall in order to make the corn grow, any more than it falls to spoil the farmer's corn when threshed out of doors, applies the same argument to organisation; and adds (as translated by Mr. Clair Grece, who first pointed out the passage to me), "So what hinders the different parts (of the body) from having this merely accidental relation in nature? as the teeth, for example, grow by necessity, the front ones sharp, adapted for dividing, and the grinders flat, and serviceable for masticating the food; since they were not made for the sake of this, but it was the result of accident. And in like manner as to other parts in which there appears to exist an adaptation to an end. Wheresoever, therefore, all things together (that is all the parts of one whole) happened like as if they were made for the sake of something, these were preserved, having been appropriately constituted by an internal spontaneity; and whatsoever things were not thus constituted, perished and still perish." We here see the principle of natural selection shadowed forth, but how little Aristotle fully comprehended the principle, is shown by his remarks on the formation of the teeth.), the first author who in modern times has treated it in a scientific spirit was Buffon. But as his opinions fluctuated greatly at different periods, and as he does not enter on the causes or means of the transformation of species, I need not here enter on details. Lamarck was the first man whose conclusions on the subject excited much attention. This justly celebrated naturalist first published his views in 1801; he much enlarged them in 1809 in his "Philosophie Zoologique", and subsequently, 1815, in the Introduction to his "Hist. Nat. des Animaux sans Vertebres". In these works he up holds the doctrine that all species, including man, are descended from other species. He first did the eminent service of arousing attention to the probability of all change in the organic, as well as in the inorganic world, being the result of law, and not of miraculous interposition. Lamarck seems to have been chiefly led to his conclusion on the gradual change of species, by the difficulty of distinguishing species and varieties, by the almost perfect gradation of forms in certain groups, and by the analogy of domestic productions. With respect to the means of modification, he attributed something to the direct action of the physical conditions of life, something to the crossing of already existing forms, and much to use and disuse, that is, to the effects of habit. To this latter agency he seems to attribute all the beautiful adaptations in nature; such as the long neck of the giraffe for browsing on the branches of trees. But he likewise believed in a law of progressive development, and as all the forms of life thus tend to progress, in order to account for the existence at the present day of simple productions, he maintains that such forms are now spontaneously generated. (I have taken the date of the first publication of Lamarck from Isidore Geoffroy Saint-Hilaire's ("Hist. Nat. Generale", tom. ii. page 405, 1859) excellent history of opinion on this subject. In this work a full account is given of Buffon's conclusions on the same subject. It is curious how largely my grandfather, Dr. Erasmus Darwin, anticipated the views and erroneous grounds of opinion of Lamarck in his "Zoonomia" (vol. i. pages 500-510), published in 1794. According to Isid. Geoffroy there is no doubt that Goethe was an extreme partisan of similar views, as shown in the introduction to a work written in 1794 and 1795, but not published till long afterward; he has pointedly remarked ("Goethe als Naturforscher", von Dr. Karl Meding, s. 34) that the future question for naturalists will be how, for instance, cattle got their horns and not for what they are used. It is rather a singular instance of the manner in which similar views arise at about the same time, that Goethe in Germany, Dr. Darwin in England, and Geoffroy Saint-Hilaire (as we shall immediately see) in France, came to the same conclusion on the origin of species, in the years 1794-5.) Geoffroy Saint-Hilaire, as is stated in his "Life", written by his son, suspected, as early as 1795, that what we call species are various degenerations of the same type. It was not until 1828 that he published his conviction that the same forms have not been perpetuated since the origin of all things. Geoffroy seems to have relied chiefly on the conditions of life, or the "monde ambiant" as the cause of change. He was cautious in drawing conclusions, and did not believe that existing species are now undergoing modification; and, as his son adds, "C'est donc un probleme a reserver entierement a l'avenir, suppose meme que l'avenir doive avoir prise sur lui." In 1813 Dr. W.C. Wells read before the Royal Society "An Account of a White Female, part of whose skin resembles that of a Negro"; but his paper was not published until his famous "Two Essays upon Dew and Single Vision" appeared in 1818. In this paper he distinctly recognises the principle of natural selection, and this is the first recognition which has been indicated; but he applies it only to the races of man, and to certain characters alone. After remarking that negroes and mulattoes enjoy an immunity from certain tropical diseases, he observes, firstly, that all animals tend to vary in some degree, and, secondly, that agriculturists improve their domesticated animals by selection; and then, he adds, but what is done in this latter case "by art, seems to be done with equal efficacy, though more slowly, by nature, in the formation of varieties of mankind, fitted for the country which they inhabit. Of the accidental varieties of man, which would occur among the first few and scattered inhabitants of the middle regions of Africa, some one would be better fitted than others to bear the diseases of the country. This race would consequently multiply, while the others would decrease; not only from their in ability to sustain the attacks of disease, but from their incapacity of contending with their more vigorous neighbours. The colour of this vigorous race I take for granted, from what has been already said, would be dark. But the same disposition to form varieties still existing, a darker and a darker race would in the course of time occur: and as the darkest would be the best fitted for the climate, this would at length become the most prevalent, if not the only race, in the particular country in which it had originated." He then extends these same views to the white inhabitants of colder climates. I am indebted to Mr. Rowley, of the United States, for having called my attention, through Mr. Brace, to the above passage of Dr. Wells' work. The Hon. and Rev. W. Herbert, afterward Dean of Manchester, in the fourth volume of the "Horticultural Transactions", 1822, and in his work on the "Amaryllidaceae" (1837, pages 19, 339), declares that "horticultural experiments have established, beyond the possibility of refutation, that botanical species are only a higher and more permanent class of varieties." He extends the same view to animals. The dean believes that single species of each genus were created in an originally highly plastic condition, and that these have produced, chiefly by inter-crossing, but likewise by variation, all our existing species. In 1826 Professor Grant, in the concluding paragraph in his well-known paper ("Edinburgh Philosophical Journal", vol. XIV, page 283) on the Spongilla, clearly declares his belief that species are descended from other species, and that they become improved in the course of modification. This same view was given in his Fifty-fifth Lecture, published in the "Lancet" in 1834. In 1831 Mr. Patrick Matthew published his work on "Naval Timber and Arboriculture", in which he gives precisely the same view on the origin of species as that (presently to be alluded to) propounded by Mr. Wallace and myself in the "Linnean Journal", and as that enlarged in the present volume. Unfortunately the view was given by Mr. Matthew very briefly in scattered passages in an appendix to a work on a different subject, so that it remained unnoticed until Mr. Matthew himself drew attention to it in the "Gardeners' Chronicle", on April 7, 1860. The differences of Mr. Matthew's views from mine are not of much importance: he seems to consider that the world was nearly depopulated at successive periods, and then restocked; and he gives as an alternative, that new forms may be generated "without the presence of any mold or germ of former aggregates." I am not sure that I understand some passages; but it seems that he attributes much influence to the direct action of the conditions of life. He clearly saw, however, the full force of the principle of natural selection. The celebrated geologist and naturalist, Von Buch, in his excellent "Description Physique des Isles Canaries" (1836, page 147), clearly expresses his belief that varieties slowly become changed into permanent species, which are no longer capable of intercrossing. Rafinesque, in his "New Flora of North America", published in 1836, wrote (page 6) as follows: "All species might have been varieties once, and many varieties are gradually becoming species by assuming constant and peculiar characters;" but further on (page 18) he adds, "except the original types or ancestors of the genus." In 1843-44 Professor Haldeman ("Boston Journal of Nat. Hist. U. States", vol. iv, page 468) has ably given the arguments for and against the hypothesis of the development and modification of species: he seems to lean toward the side of change. The "Vestiges of Creation" appeared in 1844. In the tenth and much improved edition (1853) the anonymous author says (page 155): "The proposition determined on after much consideration is, that the several series of animated beings, from the simplest and oldest up to the highest and most recent, are, under the providence of God, the results, FIRST, of an impulse which has been imparted to the forms of life, advancing them, in definite times, by generation, through grades of organisation terminating in the highest dicotyledons and vertebrata, these grades being few in number, and generally marked by intervals of organic character, which we find to be a practical difficulty in ascertaining affinities; SECOND, of another impulse connected with the vital forces, tending, in the course of generations, to modify organic structures in accordance with external circumstances, as food, the nature of the habitat, and the meteoric agencies, these being the 'adaptations' of the natural theologian." The author apparently believes that organisation progresses by sudden leaps, but that the effects produced by the conditions of life are gradual. He argues with much force on general grounds that species are not immutable productions. But I cannot see how the two supposed "impulses" account in a scientific sense for the numerous and beautiful coadaptations which we see throughout nature; I cannot see that we thus gain any insight how, for instance, a woodpecker has become adapted to its peculiar habits of life. The work, from its powerful and brilliant style, though displaying in the early editions little accurate knowledge and a great want of scientific caution, immediately had a very wide circulation. In my opinion it has done excellent service in this country in calling attention to the subject, in removing prejudice, and in thus preparing the ground for the reception of analogous views. In 1846 the veteran geologist M.J. d'Omalius d'Halloy published in an excellent though short paper ("Bulletins de l'Acad. Roy. Bruxelles", tom. xiii, page 581) his opinion that it is more probable that new species have been produced by descent with modification than that they have been separately created: the author first promulgated this opinion in 1831. Professor Owen, in 1849 ("Nature of Limbs", page 86), wrote as follows: "The archetypal idea was manifested in the flesh under diverse such modifications, upon this planet, long prior to the existence of those animal species that actually exemplify it. To what natural laws or secondary causes the orderly succession and progression of such organic phenomena may have been committed, we, as yet, are ignorant." In his address to the British Association, in 1858, he speaks (page li) of "the axiom of the continuous operation of creative power, or of the ordained becoming of living things." Further on (page xc), after referring to geographical distribution, he adds, "These phenomena shake our confidence in the conclusion that the Apteryx of New Zealand and the Red Grouse of England were distinct creations in and for those islands respectively. Always, also, it may be well to bear in mind that by the word 'creation' the zoologist means 'a process he knows not what.'" He amplifies this idea by adding that when such cases as that of the Red Grouse are "enumerated by the zoologist as evidence of distinct creation of the bird in and for such islands, he chiefly expresses that he knows not how the Red Grouse came to be there, and there exclusively; signifying also, by this mode of expressing such ignorance, his belief that both the bird and the islands owed their origin to a great first Creative Cause." If we interpret these sentences given in the same address, one by the other, it appears that this eminent philosopher felt in 1858 his confidence shaken that the Apteryx and the Red Grouse first appeared in their respective homes "he knew not how," or by some process "he knew not what." This address was delivered after the papers by Mr. Wallace and myself on the Origin of Species, presently to be referred to, had been read before the Linnean Society. When the first edition of this work was published, I was so completely deceived, as were many others, by such expressions as "the continuous operation of creative power," that I included Professor Owen with other palaeontologists as being firmly convinced of the immutability of species; but it appears ("Anat. of Vertebrates", vol. iii, page 796) that this was on my part a preposterous error. In the last edition of this work I inferred, and the inference still seems to me perfectly just, from a passage beginning with the words "no doubt the type-form," etc.(Ibid., vol. i, page xxxv), that Professor Owen admitted that natural selection may have done something in the formation of a new species; but this it appears (Ibid., vol. iii. page 798) is inaccurate and without evidence. I also gave some extracts from a correspondence between Professor Owen and the editor of the "London Review", from which it appeared manifest to the editor as well as to myself, that Professor Owen claimed to have promulgated the theory of natural selection before I had done so; and I expressed my surprise and satisfaction at this announcement; but as far as it is possible to understand certain recently published passages (Ibid., vol. iii. page 798) I have either partially or wholly again fallen into error. It is consolatory to me that others find Professor Owen's controversial writings as difficult to understand and to reconcile with each other, as I do. As far as the mere enunciation of the principle of natural selection is concerned, it is quite immaterial whether or not Professor Owen preceded me, for both of us, as shown in this historical sketch, were long ago preceded by Dr. Wells and Mr. Matthews. M. Isidore Geoffroy Saint-Hilaire, in his lectures delivered in 1850 (of which a Resume appeared in the "Revue et Mag. de Zoolog.", Jan., 1851), briefly gives his reason for believing that specific characters "sont fixes, pour chaque espece, tant qu'elle se perpetue au milieu des memes circonstances: ils se modifient, si les circonstances ambiantes viennent a changer. En resume, L'OBSERVATION des animaux sauvages demontre deja la variabilite LIMITEE des especes. Les EXPERIENCES sur les animaux sauvages devenus domestiques, et sur les animaux domestiques redevenus sauvages, la demontrent plus clairment encore. Ces memes experiences prouvent, de plus, que les differences produites peuvent etre de VALEUR GENERIQUE." In his "Hist. Nat. Generale" (tom. ii, page 430, 1859) he amplifies analogous conclusions. From a circular lately issued it appears that Dr. Freke, in 1851 ("Dublin Medical Press", page 322), propounded the doctrine that all organic beings have descended from one primordial form. His grounds of belief and treatment of the subject are wholly different from mine; but as Dr. Freke has now (1861) published his Essay on the "Origin of Species by means of Organic Affinity", the difficult attempt to give any idea of his views would be superfluous on my part. Mr. Herbert Spencer, in an Essay (originally published in the "Leader", March, 1852, and republished in his "Essays", in 1858), has contrasted the theories of the Creation and the Development of organic beings with remarkable skill and force. He argues from the analogy of domestic productions, from the changes which the embryos of many species undergo, from the difficulty of distinguishing species and varieties, and from the principle of general gradation, that species have been modified; and he attributes the modification to the change of circumstances. The author (1855) has also treated Psychology on the principle of the necessary acquirement of each mental power and capacity by gradation. In 1852 M. Naudin, a distinguished botanist, expressly stated, in an admirable paper on the Origin of Species ("Revue Horticole", page 102; since partly republished in the "Nouvelles Archives du Museum", tom. i, page 171), his belief that species are formed in an analogous manner as varieties are under cultivation; and the latter process he attributes to man's power of selection. But he does not show how selection acts under nature. He believes, like Dean Herbert, that species, when nascent, were more plastic than at present. He lays weight on what he calls the principle of finality, "puissance mysterieuse, indeterminee; fatalite pour les uns; pour les autres volonte providentielle, dont l'action incessante sur les etres vivantes determine, a toutes les epoques de l'existence du monde, la forme, le volume, et la duree de chacun d'eux, en raison de sa destinee dans l'ordre de choses dont il fait partie. C'est cette puissance qui harmonise chaque membre a l'ensemble, en l'appropriant a la fonction qu'il doit remplir dans l'organisme general de la nature, fonction qui est pour lui sa raison d'etre." (From references in Bronn's "Untersuchungen uber die Entwickelungs-Gesetze", it appears that the celebrated botanist and palaeontologist Unger published, in 1852, his belief that species undergo development and modification. Dalton, likewise, in Pander and Dalton's work on Fossil Sloths, expressed, in 1821, a similar belief. Similar views have, as is well known, been maintained by Oken in his mystical "Natur-Philosophie". From other references in Godron's work "Sur l'Espece", it seems that Bory St. Vincent, Burdach, Poiret and Fries, have all admitted that new species are continually being produced. I may add, that of the thirty-four authors named in this Historical Sketch, who believe in the modification of species, or at least disbelieve in separate acts of creation, twenty-seven have written on special branches of natural history or geology.) In 1853 a celebrated geologist, Count Keyserling ("Bulletin de la Soc. Geolog.", 2nd Ser., tom. x, page 357), suggested that as new diseases, supposed to have been caused by some miasma have arisen and spread over the world, so at certain periods the germs of existing species may have been chemically affected by circumambient molecules of a particular nature, and thus have given rise to new forms. In this same year, 1853, Dr. Schaaffhausen published an excellent pamphlet ("Verhand. des Naturhist. Vereins der Preuss. Rheinlands", etc.), in which he maintains the development of organic forms on the earth. He infers that many species have kept true for long periods, whereas a few have become modified. The distinction of species he explains by the destruction of intermediate graduated forms. "Thus living plants and animals are not separated from the extinct by new creations, but are to be regarded as their descendants through continued reproduction." A well-known French botanist, M. Lecoq, writes in 1854 ("Etudes sur Geograph." Bot. tom. i, page 250), "On voit que nos recherches sur la fixite ou la variation de l'espece, nous conduisent directement aux idees emises par deux hommes justement celebres, Geoffroy Saint-Hilaire et Goethe." Some other passages scattered through M. Lecoq's large work make it a little doubtful how far he extends his views on the modification of species. The "Philosophy of Creation" has been treated in a masterly manner by the Rev. Baden Powell, in his "Essays on the Unity of Worlds", 1855. Nothing can be more striking than the manner in which he shows that the introduction of new species is "a regular, not a casual phenomenon," or, as Sir John Herschel expresses it, "a natural in contradistinction to a miraculous process." The third volume of the "Journal of the Linnean Society" contains papers, read July 1, 1858, by Mr. Wallace and myself, in which, as stated in the introductory remarks to this volume, the theory of Natural Selection is promulgated by Mr. Wallace with admirable force and clearness. Von Baer, toward whom all zoologists feel so profound a respect, expressed about the year 1859 (see Prof. Rudolph Wagner, "Zoologisch-Anthropologische Untersuchungen", 1861, s. 51) his conviction, chiefly grounded on the laws of geographical distribution, that forms now perfectly distinct have descended from a single parent-form. In June, 1859, Professor Huxley gave a lecture before the Royal Institution on the "Persistent Types of Animal Life". Referring to such cases, he remarks, "It is difficult to comprehend the meaning of such facts as these, if we suppose that each species of animal and plant, or each great type of organisation, was formed and placed upon the surface of the globe at long intervals by a distinct act of creative power; and it is well to recollect that such an assumption is as unsupported by tradition or revelation as it is opposed to the general analogy of nature. If, on the other hand, we view "Persistent Types" in relation to that hypothesis which supposes the species living at any time to be the result of the gradual modification of pre-existing species, a hypothesis which, though unproven, and sadly damaged by some of its supporters, is yet the only one to which physiology lends any countenance; their existence would seem to show that the amount of modification which living beings have undergone during geological time is but very small in relation to the whole series of changes which they have suffered." In December, 1859, Dr. Hooker published his "Introduction to the Australian Flora". In the first part of this great work he admits the truth of the descent and modification of species, and supports this doctrine by many original observations. The first edition of this work was published on November 24, 1859, and the second edition on January 7, 1860. CONTENTS. INTRODUCTION CHAPTER I. VARIATION UNDER DOMESTICATION. Causes of Variability--Effects of Habit and the use or disuse of Parts--Correlated Variation--Inheritance--Character of Domestic Varieties--Difficulty of distinguishing between Varieties and Species--Origin of Domestic Varieties from one or more Species--Domestic Pigeons, their Differences and Origin--Principles of Selection, anciently followed, their Effects--Methodical and Unconscious Selection--Unknown Origin of our Domestic Productions--Circumstances favourable to Man's power of Selection. CHAPTER II. VARIATION UNDER NATURE. Variability--Individual Differences--Doubtful species--Wide ranging, much diffused, and common species, vary most--Species of the larger genera in each country vary more frequently than the species of the smaller genera--Many of the species of the larger genera resemble varieties in being very closely, but unequally, related to each other, and in having restricted ranges. CHAPTER III. STRUGGLE FOR EXISTENCE. Its bearing on natural selection--The term used in a wide sense--Geometrical ratio of increase--Rapid increase of naturalised animals and plants--Nature of the checks to increase--Competition universal--Effects of climate--Protection from the number of individuals--Complex relations of all animals and plants throughout nature--Struggle for life most severe between individuals and varieties of the same species; often severe between species of the same genus--The relation of organism to organism the most important of all relations. CHAPTER IV. NATURAL SELECTION; OR THE SURVIVAL OF THE FITTEST. Natural Selection--its power compared with man's selection--its power on characters of trifling importance--its power at all ages and on both sexes--Sexual Selection--On the generality of intercrosses between individuals of the same species--Circumstances favourable and unfavourable to the results of Natural Selection, namely, intercrossing, isolation, number of individuals--Slow action--Extinction caused by Natural Selection--Divergence of Character, related to the diversity of inhabitants of any small area and to naturalisation--Action of Natural Selection, through Divergence of Character and Extinction, on the descendants from a common parent--Explains the Grouping of all organic beings--Advance in organisation--Low forms preserved--Convergence of character--Indefinite multiplication of species--Summary. CHAPTER V. LAWS OF VARIATION. Effects of changed conditions--Use and disuse, combined with natural selection; organs of flight and of vision--Acclimatisation--Correlated variation--Compensation and economy of growth--False correlations--Multiple, rudimentary, and lowly organised structures variable--Parts developed in an unusual manner are highly variable; specific characters more variable than generic; secondary sexual characters variable--Species of the same genus vary in an analogous manner--Reversions to long-lost characters--Summary. CHAPTER VI. DIFFICULTIES OF THE THEORY. Difficulties of the theory of descent with modification--Absence or rarity of transitional varieties--Transitions in habits of life--Diversified habits in the same species--Species with habits widely different from those of their allies--Organs of extreme perfection--Modes of transition--Cases of difficulty--Natura non facit saltum--Organs of small importance--Organs not in all cases absolutely perfect--The law of Unity of Type and of the Conditions of Existence embraced by the theory of Natural Selection. CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION. Longevity--Modifications not necessarily simultaneous--Modifications apparently of no direct service--Progressive development--Characters of small functional importance, the most constant--Supposed incompetence of natural selection to account for the incipient stages of useful structures--Causes which interfere with the acquisition through natural selection of useful structures--Gradations of structure with changed functions--Widely different organs in members of the same class, developed from one and the same source--Reasons for disbelieving in great and abrupt modifications. CHAPTER VIII. INSTINCT. Instincts comparable with habits, but different in their origin--Instincts graduated--Aphides and ants--Instincts variable--Domestic instincts, their origin--Natural instincts of the cuckoo, molothrus, ostrich, and parasitic bees--Slave-making ants--Hive-bee, its cell-making instinct--Changes of instinct and structure not necessarily simultaneous--Difficulties on the theory of the Natural Selection of instincts--Neuter or sterile insects--Summary. CHAPTER IX. HYBRIDISM. Distinction between the sterility of first crosses and of hybrids--Sterility various in degree, not universal, affected by close interbreeding, removed by domestication--Laws governing the sterility of hybrids--Sterility not a special endowment, but incidental on other differences, not accumulated by natural selection--Causes of the sterility of first crosses and of hybrids--Parallelism between the effects of changed conditions of life and of crossing--Dimorphism and Trimorphism--Fertility of varieties when crossed and of their mongrel offspring not universal--Hybrids and mongrels compared independently of their fertility--Summary. CHAPTER X. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD. On the absence of intermediate varieties at the present day--On the nature of extinct intermediate varieties; on their number--On the lapse of time, as inferred from the rate of denudation and of deposition--On the lapse of time as estimated in years--On the poorness of our palaeontological collections--On the intermittence of geological formations--On the denudation of granitic areas--On the absence of intermediate varieties in any one formation--On the sudden appearance of groups of species--On their sudden appearance in the lowest known fossiliferous strata--Antiquity of the habitable earth. CHAPTER XI. ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS. On the slow and successive appearance of new species--On their different rates of change--Species once lost do not reappear--Groups of species follow the same general rules in their appearance and disappearance as do single species--On extinction--On simultaneous changes in the forms of life throughout the world--On the affinities of extinct species to each other and to living species--On the state of development of ancient forms--On the succession of the same types within the same areas--Summary of preceding and present chapter. CHAPTER XII. GEOGRAPHICAL DISTRIBUTION. Present distribution cannot be accounted for by differences in physical conditions--Importance of barriers--Affinity of the productions of the same continent--Centres of creation--Means of dispersal by changes of climate and of the level of the land, and by occasional means--Dispersal during the Glacial period--Alternate Glacial periods in the north and south. CHAPTER XIII. GEOGRAPHICAL DISTRIBUTION--CONTINUED. Distribution of fresh-water productions--On the inhabitants of oceanic islands--Absence of Batrachians and of terrestrial Mammals--On the relation of the inhabitants of islands to those of the nearest mainland--On colonisation from the nearest source with subsequent modification--Summary of the last and present chapter. CHAPTER XIV. MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY--EMBRYOLOGY--RUDIMENTARY ORGANS. Classification, groups subordinate to groups--Natural system--Rules and difficulties in classification, explained on the theory of descent with modification--Classification of varieties--Descent always used in classification--Analogical or adaptive characters--Affinities, general, complex and radiating--Extinction separates and defines groups--Morphology, between members of the same class, between parts of the same individual--Embryology, laws of, explained by variations not supervening at an early age, and being inherited at a corresponding age--Rudimentary Organs; their origin explained--Summary. CHAPTER XV. RECAPITULATION AND CONCLUSION. Recapitulation of the objections to the theory of Natural Selection--Recapitulation of the general and special circumstances in its favour--Causes of the general belief in the immutability of species--How far the theory of Natural Selection may be extended--Effects of its adoption on the study of Natural history--Concluding remarks. GLOSSARY OF SCIENTIFIC TERMS. INDEX. ORIGIN OF SPECIES. INTRODUCTION. When on board H.M.S. Beagle, as naturalist, I was much struck with certain facts in the distribution of the organic beings inhabiting South America, and in the geological relations of the present to the past inhabitants of that continent. These facts, as will be seen in the latter chapters of this volume, seemed to throw some light on the origin of species--that mystery of mysteries, as it has been called by one of our greatest philosophers. On my return home, it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work I allowed myself to speculate on the subject, and drew up some short notes; these I enlarged in 1844 into a sketch of the conclusions, which then seemed to me probable: from that period to the present day I have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show that I have not been hasty in coming to a decision. My work is now (1859) nearly finished; but as it will take me many more years to complete it, and as my health is far from strong, I have been urged to publish this abstract. I have more especially been induced to do this, as Mr. Wallace, who is now studying the natural history of the Malay Archipelago, has arrived at almost exactly the same general conclusions that I have on the origin of species. In 1858 he sent me a memoir on this subject, with a request that I would forward it to Sir Charles Lyell, who sent it to the Linnean Society, and it is published in the third volume of the Journal of that Society. Sir C. Lyell and Dr. Hooker, who both knew of my work--the latter having read my sketch of 1844--honoured me by thinking it advisable to publish, with Mr. Wallace's excellent memoir, some brief extracts from my manuscripts. This abstract, which I now publish, must necessarily be imperfect. I cannot here give references and authorities for my several statements; and I must trust to the reader reposing some confidence in my accuracy. No doubt errors may have crept in, though I hope I have always been cautious in trusting to good authorities alone. I can here give only the general conclusions at which I have arrived, with a few facts in illustration, but which, I hope, in most cases will suffice. No one can feel more sensible than I do of the necessity of hereafter publishing in detail all the facts, with references, on which my conclusions have been grounded; and I hope in a future work to do this. For I am well aware that scarcely a single point is discussed in this volume on which facts cannot be adduced, often apparently leading to conclusions directly opposite to those at which I have arrived. A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question; and this is here impossible. I much regret that want of space prevents my having the satisfaction of acknowledging the generous assistance which I have received from very many naturalists, some of them personally unknown to me. I cannot, however, let this opportunity pass without expressing my deep obligations to Dr. Hooker, who, for the last fifteen years, has aided me in every possible way by his large stores of knowledge and his excellent judgment. In considering the origin of species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species, inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which justly excites our admiration. Naturalists continually refer to external conditions, such as climate, food, etc., as the only possible cause of variation. In one limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the mistletoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself. It is, therefore, of the highest importance to gain a clear insight into the means of modification and coadaptation. At the commencement of my observations it seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this obscure problem. Nor have I been disappointed; in this and in all other perplexing cases I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the best and safest clue. I may venture to express my conviction of the high value of such studies, although they have been very commonly neglected by naturalists. From these considerations, I shall devote the first chapter of this abstract to variation under domestication. We shall thus see that a large amount of hereditary modification is at least possible; and, what is equally or more important, we shall see how great is the power of man in accumulating by his selection successive slight variations. I will then pass on to the variability of species in a state of nature; but I shall, unfortunately, be compelled to treat this subject far too briefly, as it can be treated properly only by giving long catalogues of facts. We shall, however, be enabled to discuss what circumstances are most favourable to variation. In the next chapter the struggle for existence among all organic beings throughout the world, which inevitably follows from the high geometrical ratio of their increase, will be considered. This is the doctrine of Malthus, applied to the whole animal and vegetable kingdoms. As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be NATURALLY SELECTED. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form. This fundamental subject of natural selection will be treated at some length in the fourth chapter; and we shall then see how natural selection almost inevitably causes much extinction of the less improved forms of life, and leads to what I have called divergence of character. In the next chapter I shall discuss the complex and little known laws of variation. In the five succeeding chapters, the most apparent and gravest difficulties in accepting the theory will be given: namely, first, the difficulties of transitions, or how a simple being or a simple organ can be changed and perfected into a highly developed being or into an elaborately constructed organ; secondly the subject of instinct, or the mental powers of animals; thirdly, hybridism, or the infertility of species and the fertility of varieties when intercrossed; and fourthly, the imperfection of the geological record. In the next chapter I shall consider the geological succession of organic beings throughout time; in the twelfth and thirteenth, their geographical distribution throughout space; in the fourteenth, their classification or mutual affinities, both when mature and in an embryonic condition. In the last chapter I shall give a brief recapitulation of the whole work, and a few concluding remarks. No one ought to feel surprise at much remaining as yet unexplained in regard to the origin of species and varieties, if he make due allowance for our profound ignorance in regard to the mutual relations of the many beings which live around us. Who can explain why one species ranges widely and is very numerous, and why another allied species has a narrow range and is rare? Yet these relations are of the highest importance, for they determine the present welfare and, as I believe, the future success and modification of every inhabitant of this world. Still less do we know of the mutual relations of the innumerable inhabitants of the world during the many past geological epochs in its history. Although much remains obscure, and will long remain obscure, I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists until recently entertained, and which I formerly entertained--namely, that each species has been independently created--is erroneous. I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am convinced that natural selection has been the most important, but not the exclusive, means of modification. CHAPTER I. VARIATION UNDER DOMESTICATION. Causes of Variability--Effects of Habit and the use and disuse of Parts--Correlated Variation--Inheritance--Character of Domestic Varieties--Difficulty of distinguishing between Varieties and Species--Origin of Domestic Varieties from one or more Species--Domestic Pigeons, their Differences and Origin--Principles of Selection, anciently followed, their Effects--Methodical and Unconscious Selection--Unknown Origin of our Domestic Productions--Circumstances favourable to Man's power of Selection. CAUSES OF VARIABILITY. When we compare the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us is, that they generally differ more from each other than do the individuals of any one species or variety in a state of nature. And if we reflect on the vast diversity of the plants and animals which have been cultivated, and which have varied during all ages under the most different climates and treatment, we are driven to conclude that this great variability is due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent species had been exposed under nature. There is, also, some probability in the view propounded by Andrew Knight, that this variability may be partly connected with excess of food. It seems clear that organic beings must be exposed during several generations to new conditions to cause any great amount of variation; and that, when the organisation has once begun to vary, it generally continues varying for many generations. No case is on record of a variable organism ceasing to vary under cultivation. Our oldest cultivated plants, such as wheat, still yield new varieties: our oldest domesticated animals are still capable of rapid improvement or modification. As far as I am able to judge, after long attending to the subject, the conditions of life appear to act in two ways--directly on the whole organisation or on certain parts alone and in directly by affecting the reproductive system. With respect to the direct action, we must bear in mind that in every case, as Professor Weismann has lately insisted, and as I have incidently shown in my work on "Variation under Domestication," there are two factors: namely, the nature of the organism and the nature of the conditions. The former seems to be much the more important; for nearly similar variations sometimes arise under, as far as we can judge, dissimilar conditions; and, on the other hand, dissimilar variations arise under conditions which appear to be nearly uniform. The effects on the offspring are either definite or in definite. They may be considered as definite when all or nearly all the offspring of individuals exposed to certain conditions during several generations are modified in the same manner. It is extremely difficult to come to any conclusion in regard to the extent of the changes which have been thus definitely induced. There can, however, be little doubt about many slight changes, such as size from the amount of food, colour from the nature of the food, thickness of the skin and hair from climate, etc. Each of the endless variations which we see in the plumage of our fowls must have had some efficient cause; and if the same cause were to act uniformly during a long series of generations on many individuals, all probably would be modified in the same manner. Such facts as the complex and extraordinary out growths which variably follow from the insertion of a minute drop of poison by a gall-producing insect, shows us what singular modifications might result in the case of plants from a chemical change in the nature of the sap. In definite variability is a much more common result of changed conditions than definite variability, and has probably played a more important part in the formation of our domestic races. We see in definite variability in the endless slight peculiarities which distinguish the individuals of the same species, and which cannot be accounted for by inheritance from either parent or from some more remote ancestor. Even strongly-marked differences occasionally appear in the young of the same litter, and in seedlings from the same seed-capsule. At long intervals of time, out of millions of individuals reared in the same country and fed on nearly the same food, deviations of structure so strongly pronounced as to deserve to be called monstrosities arise; but monstrosities cannot be separated by any distinct line from slighter variations. All such changes of structure, whether extremely slight or strongly marked, which appear among many individuals living together, may be considered as the in definite effects of the conditions of life on each individual organism, in nearly the same manner as the chill effects different men in an in definite manner, according to their state of body or constitution, causing coughs or colds, rheumatism, or inflammation of various organs. With respect to what I have called the in direct action of changed conditions, namely, through the reproductive system of being affected, we may infer that variability is thus induced, partly from the fact of this system being extremely sensitive to any change in the conditions, and partly from the similarity, as Kolreuter and others have remarked, between the variability which follows from the crossing of distinct species, and that which may be observed with plants and animals when reared under new or unnatural conditions. Many facts clearly show how eminently susceptible the reproductive system is to very slight changes in the surrounding conditions. Nothing is more easy than to tame an animal, and few things more difficult than to get it to breed freely under confinement, even when the male and female unite. How many animals there are which will not breed, though kept in an almost free state in their native country! This is generally, but erroneously attributed to vitiated instincts. Many cultivated plants display the utmost vigour, and yet rarely or never seed! In some few cases it has been discovered that a very trifling change, such as a little more or less water at some particular period of growth, will determine whether or not a plant will produce seeds. I cannot here give the details which I have collected and elsewhere published on this curious subject; but to show how singular the laws are which determine the reproduction of animals under confinement, I may mention that carnivorous animals, even from the tropics, breed in this country pretty freely under confinement, with the exception of the plantigrades or bear family, which seldom produce young; whereas, carnivorous birds, with the rarest exception, hardly ever lay fertile eggs. Many exotic plants have pollen utterly worthless, in the same condition as in the most sterile hybrids. When, on the one hand, we see domesticated animals and plants, though often weak and sickly, breeding freely under confinement; and when, on the other hand, we see individuals, though taken young from a state of nature perfectly tamed, long-lived, and healthy (of which I could give numerous instances), yet having their reproductive system so seriously affected by unperceived causes as to fail to act, we need not be surprised at this system, when it does act under confinement, acting irregularly, and producing offspring somewhat unlike their parents. I may add that as some organisms breed freely under the most unnatural conditions--for instance, rabbits and ferrets kept in hutches--showing that their reproductive organs are not easily affected; so will some animals and plants withstand domestication or cultivation, and vary very slightly--perhaps hardly more than in a state of nature. Some naturalists have maintained that all variations are connected with the act of sexual reproduction; but this is certainly an error; for I have given in another work a long list of "sporting plants;" as they are called by gardeners; that is, of plants which have suddenly produced a single bud with a new and sometimes widely different character from that of the other buds on the same plant. These bud variations, as they may be named, can be propagated by grafts, offsets, etc., and sometimes by seed. They occur rarely under nature, but are far from rare under culture. As a single bud out of many thousands produced year after year on the same tree under uniform conditions, has been known suddenly to assume a new character; and as buds on distinct trees, growing under different conditions, have sometimes yielded nearly the same variety--for instance, buds on peach-trees producing nectarines, and buds on common roses producing moss-roses--we clearly see that the nature of the conditions is of subordinate importance in comparison with the nature of the organism in determining each particular form of variation; perhaps of not more importance than the nature of the spark, by which a mass of combustible matter is ignited, has in determining the nature of the flames. EFFECTS OF HABIT AND OF THE USE OR DISUSE OF PARTS; CORRELATED VARIATION; INHERITANCE. Changed habits produce an inherited effect as in the period of the flowering of plants when transported from one climate to another. With animals the increased use or disuse of parts has had a more marked influence; thus I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more, in proportion to the whole skeleton, than do the same bones in the wild duck; and this change may be safely attributed to the domestic duck flying much less, and walking more, than its wild parents. The great and inherited development of the udders in cows and goats in countries where they are habitually milked, in comparison with these organs in other countries, is probably another instance of the effects of use. Not one of our domestic animals can be named which has not in some country drooping ears; and the view which has been suggested that the drooping is due to disuse of the muscles of the ear, from the animals being seldom much alarmed, seems probable. Many laws regulate variation, some few of which can be dimly seen, and will hereafter be briefly discussed. I will here only allude to what may be called correlated variation. Important changes in the embryo or larva will probably entail changes in the mature animal. In monstrosities, the correlations between quite distinct parts are very curious; and many instances are given in Isidore Geoffroy St. Hilaire's great work on this subject. Breeders believe that long limbs are almost always accompanied by an elongated head. Some instances of correlation are quite whimsical; thus cats which are entirely white and have blue eyes are generally deaf; but it has been lately stated by Mr. Tait that this is confined to the males. Colour and constitutional peculiarities go together, of which many remarkable cases could be given among animals and plants. From facts collected by Heusinger, it appears that white sheep and pigs are injured by certain plants, while dark-coloured individuals escape: Professor Wyman has recently communicated to me a good illustration of this fact; on asking some farmers in Virginia how it was that all their pigs were black, they informed him that the pigs ate the paint-root (Lachnanthes), which coloured their bones pink, and which caused the hoofs of all but the black varieties to drop off; and one of the "crackers" (i.e. Virginia squatters) added, "we select the black members of a litter for raising, as they alone have a good chance of living." Hairless dogs have imperfect teeth; long-haired and coarse-haired animals are apt to have, as is asserted, long or many horns; pigeons with feathered feet have skin between their outer toes; pigeons with short beaks have small feet, and those with long beaks large feet. Hence if man goes on selecting, and thus augmenting, any peculiarity, he will almost certainly modify unintentionally other parts of the structure, owing to the mysterious laws of correlation. The results of the various, unknown, or but dimly understood laws of variation are infinitely complex and diversified. It is well worth while carefully to study the several treatises on some of our old cultivated plants, as on the hyacinth, potato, even the dahlia, etc.; and it is really surprising to note the endless points of structure and constitution in which the varieties and sub-varieties differ slightly from each other. The whole organisation seems to have become plastic, and departs in a slight degree from that of the parental type. Any variation which is not inherited is unimportant for us. But the number and diversity of inheritable deviations of structure, both those of slight and those of considerable physiological importance, are endless. Dr. Prosper Lucas' treatise, in two large volumes, is the fullest and the best on this subject. No breeder doubts how strong is the tendency to inheritance; that like produces like is his fundamental belief: doubts have been thrown on this principle only by theoretical writers. When any deviation of structure often appears, and we see it in the father and child, we cannot tell whether it may not be due to the same cause having acted on both; but when among individuals, apparently exposed to the same conditions, any very rare deviation, due to some extraordinary combination of circumstances, appears in the parent--say, once among several million individuals--and it reappears in the child, the mere doctrine of chances almost compels us to attribute its reappearance to inheritance. Every one must have heard of cases of albinism, prickly skin, hairy bodies, etc., appearing in several members of the same family. If strange and rare deviations of structure are truly inherited, less strange and commoner deviations may be freely admitted to be inheritable. Perhaps the correct way of viewing the whole subject would be, to look at the inheritance of every character whatever as the rule, and non-inheritance as the anomaly. The laws governing inheritance are for the most part unknown; no one can say why the same peculiarity in different individuals of the same species, or in different species, is sometimes inherited and sometimes not so; why the child often reverts in certain characteristics to its grandfather or grandmother or more remote ancestor; why a peculiarity is often transmitted from one sex to both sexes, or to one sex alone, more commonly but not exclusively to the like sex. It is a fact of some importance to us, that peculiarities appearing in the males of our domestic breeds are often transmitted, either exclusively or in a much greater degree, to the males alone. A much more important rule, which I think may be trusted, is that, at whatever period of life a peculiarity first appears, it tends to reappear in the offspring at a corresponding age, though sometimes earlier. In many cases this could not be otherwise; thus the inherited peculiarities in the horns of cattle could appear only in the offspring when nearly mature; peculiarities in the silk-worm are known to appear at the corresponding caterpillar or cocoon stage. But hereditary diseases and some other facts make me believe that the rule has a wider extension, and that, when there is no apparent reason why a peculiarity should appear at any particular age, yet that it does tend to appear in the offspring at the same period at which it first appeared in the parent. I believe this rule to be of the highest importance in explaining the laws of embryology. These remarks are of course confined to the first APPEARANCE of the peculiarity, and not to the primary cause which may have acted on the ovules or on the male element; in nearly the same manner as the increased length of the horns in the offspring from a short-horned cow by a long-horned bull, though appearing late in life, is clearly due to the male element. Having alluded to the subject of reversion, I may here refer to a statement often made by naturalists--namely, that our domestic varieties, when run wild, gradually but invariably revert in character to their aboriginal stocks. Hence it has been argued that no deductions can be drawn from domestic races to species in a state of nature. I have in vain endeavoured to discover on what decisive facts the above statement has so often and so boldly been made. There would be great difficulty in proving its truth: we may safely conclude that very many of the most strongly marked domestic varieties could not possibly live in a wild state. In many cases we do not know what the aboriginal stock was, and so could not tell whether or not nearly perfect reversion had ensued. It would be necessary, in order to prevent the effects of intercrossing, that only a single variety should be turned loose in its new home. Nevertheless, as our varieties certainly do occasionally revert in some of their characters to ancestral forms, it seems to me not improbable that if we could succeed in naturalising, or were to cultivate, during many generations, the several races, for instance, of the cabbage, in very poor soil--in which case, however, some effect would have to be attributed to the DEFINITE action of the poor soil--that they would, to a large extent, or even wholly, revert to the wild aboriginal stock. Whether or not the experiment would succeed is not of great importance for our line of argument; for by the experiment itself the conditions of life are changed. If it could be shown that our domestic varieties manifested a strong tendency to reversion--that is, to lose their acquired characters, while kept under the same conditions and while kept in a considerable body, so that free intercrossing might check, by blending together, any slight deviations in their structure, in such case, I grant that we could deduce nothing from domestic varieties in regard to species. But there is not a shadow of evidence in favour of this view: to assert that we could not breed our cart and race-horses, long and short-horned cattle, and poultry of various breeds, and esculent vegetables, for an unlimited number of generations, would be opposed to all experience. CHARACTER OF DOMESTIC VARIETIES; DIFFICULTY OF DISTINGUISHING BETWEEN VARIETIES AND SPECIES; ORIGIN OF DOMESTIC VARIETIES FROM ONE OR MORE SPECIES. When we look to the hereditary varieties or races of our domestic animals and plants, and compare them with closely allied species, we generally perceive in each domestic race, as already remarked, less uniformity of character than in true species. Domestic races often have a somewhat monstrous character; by which I mean, that, although differing from each other and from other species of the same genus, in several trifling respects, they often differ in an extreme degree in some one part, both when compared one with another, and more especially when compared with the species under nature to which they are nearest allied. With these exceptions (and with that of the perfect fertility of varieties when crossed--a subject hereafter to be discussed), domestic races of the same species differ from each other in the same manner as do the closely allied species of the same genus in a state of nature, but the differences in most cases are less in degree. This must be admitted as true, for the domestic races of many animals and plants have been ranked by some competent judges as the descendants of aboriginally distinct species, and by other competent judges as mere varieties. If any well marked distinction existed between a domestic race and a species, this source of doubt would not so perpetually recur. It has often been stated that domestic races do not differ from each other in characters of generic value. It can be shown that this statement is not correct; but naturalists differ much in determining what characters are of generic value; all such valuations being at present empirical. When it is explained how genera originate under nature, it will be seen that we have no right to expect often to find a generic amount of difference in our domesticated races. In attempting to estimate the amount of structural difference between allied domestic races, we are soon involved in doubt, from not knowing whether they are descended from one or several parent species. This point, if it could be cleared up, would be interesting; if, for instance, it could be shown that the greyhound, bloodhound, terrier, spaniel and bull-dog, which we all know propagate their kind truly, were the offspring of any single species, then such facts would have great weight in making us doubt about the immutability of the many closely allied natural species--for instance, of the many foxes--inhabiting the different quarters of the world. I do not believe, as we shall presently see, that the whole amount of difference between the several breeds of the dog has been produced under domestication; I believe that a small part of the difference is due to their being descended from distinct species. In the case of strongly marked races of some other domesticated species, there is presumptive or even strong evidence that all are descended from a single wild stock. It has often been assumed that man has chosen for domestication animals and plants having an extraordinary inherent tendency to vary, and likewise to withstand diverse climates. I do not dispute that these capacities have added largely to the value of most of our domesticated productions; but how could a savage possibly know, when he first tamed an animal, whether it would vary in succeeding generations, and whether it would endure other climates? Has the little variability of the ass and goose, or the small power of endurance of warmth by the reindeer, or of cold by the common camel, prevented their domestication? I cannot doubt that if other animals and plants, equal in number to our domesticated productions, and belonging to equally diverse classes and countries, were taken from a state of nature, and could be made to breed for an equal number of generations under domestication, they would on an average vary as largely as the parent species of our existing domesticated productions have varied. In the case of most of our anciently domesticated animals and plants, it is not possible to come to any definite conclusion, whether they are descended from one or several wild species. The argument mainly relied on by those who believe in the multiple origin of our domestic animals is, that we find in the most ancient times, on the monuments of Egypt, and in the lake-habitations of Switzerland, much diversity in the breeds; and that some of these ancient breeds closely resemble, or are even identical with, those still existing. But this only throws far backward the history of civilisation, and shows that animals were domesticated at a much earlier period than has hitherto been supposed. The lake-inhabitants of Switzerland cultivated several kinds of wheat and barley, the pea, the poppy for oil and flax; and they possessed several domesticated animals. They also carried on commerce with other nations. All this clearly shows, as Heer has remarked, that they had at this early age progressed considerably in civilisation; and this again implies a long continued previous period of less advanced civilisation, during which the domesticated animals, kept by different tribes in different districts, might have varied and given rise to distinct races. Since the discovery of flint tools in the superficial formations of many parts of the world, all geologists believe that barbarian men existed at an enormously remote period; and we know that at the present day there is hardly a tribe so barbarous as not to have domesticated at least the dog. The origin of most of our domestic animals will probably forever remain vague. But I may here state that, looking to the domestic dogs of the whole world, I have, after a laborious collection of all known facts, come to the conclusion that several wild species of Canidae have been tamed, and that their blood, in some cases mingled together, flows in the veins of our domestic breeds. In regard to sheep and goats I can form no decided opinion. From facts communicated to me by Mr. Blyth, on the habits, voice, constitution and structure of the humped Indian cattle, it is almost certain that they are descended from a different aboriginal stock from our European cattle; and some competent judges believe that these latter have had two or three wild progenitors, whether or not these deserve to be called species. This conclusion, as well as that of the specific distinction between the humped and common cattle, may, indeed, be looked upon as established by the admirable researches of Professor Rutimeyer. With respect to horses, from reasons which I cannot here give, I am doubtfully inclined to believe, in opposition to several authors, that all the races belong to the same species. Having kept nearly all the English breeds of the fowl alive, having bred and crossed them, and examined their skeletons, it appears to me almost certain that all are the descendants of the wild Indian fowl, Gallus bankiva; and this is the conclusion of Mr. Blyth, and of others who have studied this bird in India. In regard to ducks and rabbits, some breeds of which differ much from each other, the evidence is clear that they are all descended from the common duck and wild rabbit. The doctrine of the origin of our several domestic races from several aboriginal stocks, has been carried to an absurd extreme by some authors. They believe that every race which breeds true, let the distinctive characters be ever so slight, has had its wild prototype. At this rate there must have existed at least a score of species of wild cattle, as many sheep, and several goats, in Europe alone, and several even within Great Britain. One author believes that there formerly existed eleven wild species of sheep peculiar to Great Britain! When we bear in mind that Britain has now not one peculiar mammal, and France but few distinct from those of Germany, and so with Hungary, Spain, etc., but that each of these kingdoms possesses several peculiar breeds of cattle, sheep, etc., we must admit that many domestic breeds must have originated in Europe; for whence otherwise could they have been derived? So it is in India. Even in the case of the breeds of the domestic dog throughout the world, which I admit are descended from several wild species, it cannot be doubted that there has been an immense amount of inherited variation; for who will believe that animals closely resembling the Italian greyhound, the bloodhound, the bull-dog, pug-dog, or Blenheim spaniel, etc.--so unlike all wild Canidae--ever existed in a state of nature? It has often been loosely said that all our races of dogs have been produced by the crossing of a few aboriginal species; but by crossing we can only get forms in some degree intermediate between their parents; and if we account for our several domestic races by this process, we must admit the former existence of the most extreme forms, as the Italian greyhound, bloodhound, bull-dog, etc., in the wild state. Moreover, the possibility of making distinct races by crossing has been greatly exaggerated. Many cases are on record showing that a race may be modified by occasional crosses if aided by the careful selection of the individuals which present the desired character; but to obtain a race intermediate between two quite distinct races would be very difficult. Sir J. Sebright expressly experimented with this object and failed. The offspring from the first cross between two pure breeds is tolerably and sometimes (as I have found with pigeons) quite uniform in character, and every thing seems simple enough; but when these mongrels are crossed one with another for several generations, hardly two of them are alike, and then the difficulty of the task becomes manifest. BREEDS OF THE DOMESTIC PIGEON, THEIR DIFFERENCES AND ORIGIN. Believing that it is always best to study some special group, I have, after deliberation, taken up domestic pigeons. I have kept every breed which I could purchase or obtain, and have been most kindly favoured with skins from several quarters of the world, more especially by the Hon. W. Elliot from India, and by the Hon. C. Murray from Persia. Many treatises in different languages have been published on pigeons, and some of them are very important, as being of considerable antiquity. I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs. The diversity of the breeds is something astonishing. Compare the English carrier and the short-faced tumbler, and see the wonderful difference in their beaks, entailing corresponding differences in their skulls. The carrier, more especially the male bird, is also remarkable from the wonderful development of the carunculated skin about the head, and this is accompanied by greatly elongated eyelids, very large external orifices to the nostrils, and a wide gape of mouth. The short-faced tumbler has a beak in outline almost like that of a finch; and the common tumbler has the singular inherited habit of flying at a great height in a compact flock, and tumbling in the air head over heels. The runt is a bird of great size, with long, massive beak and large feet; some of the sub-breeds of runts have very long necks, others very long wings and tails, others singularly short tails. The barb is allied to the carrier, but, instead of a long beak, has a very short and broad one. The pouter has a much elongated body, wings, and legs; and its enormously developed crop, which it glories in inflating, may well excite astonishment and even laughter. The turbit has a short and conical beak, with a line of reversed feathers down the breast; and it has the habit of continually expanding, slightly, the upper part of the oesophagus. The Jacobin has the feathers so much reversed along the back of the neck that they form a hood, and it has, proportionally to its size, elongated wing and tail feathers. The trumpeter and laugher, as their names express, utter a very different coo from the other breeds. The fantail has thirty or even forty tail-feathers, instead of twelve or fourteen, the normal number in all the members of the great pigeon family: these feathers are kept expanded and are carried so erect that in good birds the head and tail touch: the oil-gland is quite aborted. Several other less distinct breeds might be specified. In the skeletons of the several breeds, the development of the bones of the face, in length and breadth and curvature, differs enormously. The shape, as well as the breadth and length of the ramus of the lower jaw, varies in a highly remarkable manner. The caudal and sacral vertebrae vary in number; as does the number of the ribs, together with their relative breadth and the presence of processes. The size and shape of the apertures in the sternum are highly variable; so is the degree of divergence and relative size of the two arms of the furcula. The proportional width of the gape of mouth, the proportional length of the eyelids, of the orifice of the nostrils, of the tongue (not always in strict correlation with the length of beak), the size of the crop and of the upper part of the oesophagus; the development and abortion of the oil-gland; the number of the primary wing and caudal feathers; the relative length of the wing and tail to each other and to the body; the relative length of the leg and foot; the number of scutellae on the toes, the development of skin between the toes, are all points of structure which are variable. The period at which the perfect plumage is acquired varies, as does the state of the down with which the nestling birds are clothed when hatched. The shape and size of the eggs vary. The manner of flight, and in some breeds the voice and disposition, differ remarkably. Lastly, in certain breeds, the males and females have come to differ in a slight degree from each other. Altogether at least a score of pigeons might be chosen, which, if shown to an ornithologist, and he were told that they were wild birds, would certainly be ranked by him as well-defined species. Moreover, I do not believe that any ornithologist would in this case place the English carrier, the short-faced tumbler, the runt, the barb, pouter, and fantail in the same genus; more especially as in each of these breeds several truly-inherited sub-breeds, or species, as he would call them, could be shown him. Great as are the differences between the breeds of the pigeon, I am fully convinced that the common opinion of naturalists is correct, namely, that all are descended from the rock-pigeon (Columba livia), including under this term several geographical races or sub-species, which differ from each other in the most trifling respects. As several of the reasons which have led me to this belief are in some degree applicable in other cases, I will here briefly give them. If the several breeds are not varieties, and have not proceeded from the rock-pigeon, they must have descended from at least seven or eight aboriginal stocks; for it is impossible to make the present domestic breeds by the crossing of any lesser number: how, for instance, could a pouter be produced by crossing two breeds unless one of the parent-stocks possessed the characteristic enormous crop? The supposed aboriginal stocks must all have been rock-pigeons, that is, they did not breed or willingly perch on trees. But besides C. livia, with its geographical sub-species, only two or three other species of rock-pigeons are known; and these have not any of the characters of the domestic breeds. Hence the supposed aboriginal stocks must either still exist in the countries where they were originally domesticated, and yet be unknown to ornithologists; and this, considering their size, habits and remarkable characters, seems improbable; or they must have become extinct in the wild state. But birds breeding on precipices, and good flyers, are unlikely to be exterminated; and the common rock-pigeon, which has the same habits with the domestic breeds, has not been exterminated even on several of the smaller British islets, or on the shores of the Mediterranean. Hence the supposed extermination of so many species having similar habits with the rock-pigeon seems a very rash assumption. Moreover, the several above-named domesticated breeds have been transported to all parts of the world, and, therefore, some of them must have been carried back again into their native country; but not one has become wild or feral, though the dovecot-pigeon, which is the rock-pigeon in a very slightly altered state, has become feral in several places. Again, all recent experience shows that it is difficult to get wild animals to breed freely under domestication; yet on the hypothesis of the multiple origin of our pigeons, it must be assumed that at least seven or eight species were so thoroughly domesticated in ancient times by half-civilized man, as to be quite prolific under confinement. An argument of great weight, and applicable in several other cases, is, that the above-specified breeds, though agreeing generally with the wild rock-pigeon in constitution, habits, voice, colouring, and in most parts of their structure, yet are certainly highly abnormal in other parts; we may look in vain through the whole great family of Columbidae for a beak like that of the English carrier, or that of the short-faced tumbler, or barb; for reversed feathers like those of the Jacobin; for a crop like that of the pouter; for tail-feathers like those of the fantail. Hence it must be assumed, not only that half-civilized man succeeded in thoroughly domesticating several species, but that he intentionally or by chance picked out extraordinarily abnormal species; and further, that these very species have since all become extinct or unknown. So many strange contingencies are improbable in the highest degree. Some facts in regard to the colouring of pigeons well deserve consideration. The rock-pigeon is of a slaty-blue, with white loins; but the Indian sub-species, C. intermedia of Strickland, has this part bluish. The tail has a terminal dark bar, with the outer feathers externally edged at the base with white. The wings have two black bars. Some semi-domestic breeds, and some truly wild breeds, have, besides the two black bars, the wings chequered with black. These several marks do not occur together in any other species of the whole family. Now, in every one of the domestic breeds, taking thoroughly well-bred birds, all the above marks, even to the white edging of the outer tail-feathers, sometimes concur perfectly developed. Moreover, when birds belonging to two or more distinct breeds are crossed, none of which are blue or have any of the above-specified marks, the mongrel offspring are very apt suddenly to acquire these characters. To give one instance out of several which I have observed: I crossed some white fantails, which breed very true, with some black barbs--and it so happens that blue varieties of barbs are so rare that I never heard of an instance in England; and the mongrels were black, brown and mottled. I also crossed a barb with a spot, which is a white bird with a red tail and red spot on the forehead, and which notoriously breeds very true; the mongrels were dusky and mottled. I then crossed one of the mongrel barb-fantails with a mongrel barb-spot, and they produced a bird of as beautiful a blue colour, with the white loins, double black wing-bar, and barred and white-edged tail-feathers, as any wild rock-pigeon! We can understand these facts, on the well-known principle of reversion to ancestral characters, if all the domestic breeds are descended from the rock-pigeon. But if we deny this, we must make one of the two following highly improbable suppositions. Either, first, that all the several imagined aboriginal stocks were coloured and marked like the rock-pigeon, although no other existing species is thus coloured and marked, so that in each separate breed there might be a tendency to revert to the very same colours and markings. Or, secondly, that each breed, even the purest, has within a dozen, or at most within a score, of generations, been crossed by the rock-pigeon: I say within a dozen or twenty generations, for no instance is known of crossed descendants reverting to an ancestor of foreign blood, removed by a greater number of generations. In a breed which has been crossed only once the tendency to revert to any character derived from such a cross will naturally become less and less, as in each succeeding generation there will be less of the foreign blood; but when there has been no cross, and there is a tendency in the breed to revert to a character which was lost during some former generation, this tendency, for all that we can see to the contrary, may be transmitted undiminished for an indefinite number of generations. These two distinct cases of reversion are often confounded together by those who have written on inheritance. Lastly, the hybrids or mongrels from between all the breeds of the pigeon are perfectly fertile, as I can state from my own observations, purposely made, on the most distinct breeds. Now, hardly any cases have been ascertained with certainty of hybrids from two quite distinct species of animals being perfectly fertile. Some authors believe that long-continued domestication eliminates this strong tendency to sterility in species. From the history of the dog, and of some other domestic animals, this conclusion is probably quite correct, if applied to species closely related to each other. But to extend it so far as to suppose that species, aboriginally as distinct as carriers, tumblers, pouters, and fantails now are, should yield offspring perfectly fertile, inter se, seems to me rash in the extreme. From these several reasons, namely, the improbability of man having formerly made seven or eight supposed species of pigeons to breed freely under domestication--these supposed species being quite unknown in a wild state, and their not having become anywhere feral--these species presenting certain very abnormal characters, as compared with all other Columbidae, though so like the rock-pigeon in most other respects--the occasional reappearance of the blue colour and various black marks in all the breeds, both when kept pure and when crossed--and lastly, the mongrel offspring being perfectly fertile--from these several reasons, taken together, we may safely conclude that all our domestic breeds are descended from the rock-pigeon or Columba livia with its geographical sub-species. In favour of this view, I may add, firstly, that the wild C. livia has been found capable of domestication in Europe and in India; and that it agrees in habits and in a great number of points of structure with all the domestic breeds. Secondly, that although an English carrier or a short-faced tumbler differs immensely in certain characters from the rock-pigeon, yet that by comparing the several sub-breeds of these two races, more especially those brought from distant countries, we can make, between them and the rock-pigeon, an almost perfect series; so we can in some other cases, but not with all the breeds. Thirdly, those characters which are mainly distinctive of each breed are in each eminently variable, for instance, the wattle and length of beak of the carrier, the shortness of that of the tumbler, and the number of tail-feathers in the fantail; and the explanation of this fact will be obvious when we treat of selection. Fourthly, pigeons have been watched and tended with the utmost care, and loved by many people. They have been domesticated for thousands of years in several quarters of the world; the earliest known record of pigeons is in the fifth Aegyptian dynasty, about 3000 B.C., as was pointed out to me by Professor Lepsius; but Mr. Birch informs me that pigeons are given in a bill of fare in the previous dynasty. In the time of the Romans, as we hear from Pliny, immense prices were given for pigeons; "nay, they are come to this pass, that they can reckon up their pedigree and race." Pigeons were much valued by Akber Khan in India, about the year 1600; never less than 20,000 pigeons were taken with the court. "The monarchs of Iran and Turan sent him some very rare birds;" and, continues the courtly historian, "His Majesty, by crossing the breeds, which method was never practised before, has improved them astonishingly." About this same period the Dutch were as eager about pigeons as were the old Romans. The paramount importance of these considerations in explaining the immense amount of variation which pigeons have undergone, will likewise be obvious when we treat of selection. We shall then, also, see how it is that the several breeds so often have a somewhat monstrous character. It is also a most favourable circumstance for the production of distinct breeds, that male and female pigeons can be easily mated for life; and thus different breeds can be kept together in the same aviary. I have discussed the probable origin of domestic pigeons at some, yet quite insufficient, length; because when I first kept pigeons and watched the several kinds, well knowing how truly they breed, I felt fully as much difficulty in believing that since they had been domesticated they had all proceeded from a common parent, as any naturalist could in coming to a similar conclusion in regard to the many species of finches, or other groups of birds, in nature. One circumstance has struck me much; namely, that nearly all the breeders of the various domestic animals and the cultivators of plants, with whom I have conversed, or whose treatises I have read, are firmly convinced that the several breeds to which each has attended, are descended from so many aboriginally distinct species. Ask, as I have asked, a celebrated raiser of Hereford cattle, whether his cattle might not have descended from Long-horns, or both from a common parent-stock, and he will laugh you to scorn. I have never met a pigeon, or poultry, or duck, or rabbit fancier, who was not fully convinced that each main breed was descended from a distinct species. Van Mons, in his treatise on pears and apples, shows how utterly he disbelieves that the several sorts, for instance a Ribston-pippin or Codlin-apple, could ever have proceeded from the seeds of the same tree. Innumerable other examples could be given. The explanation, I think, is simple: from long-continued study they are strongly impressed with the differences between the several races; and though they well know that each race varies slightly, for they win their prizes by selecting such slight differences, yet they ignore all general arguments, and refuse to sum up in their minds slight differences accumulated during many successive generations. May not those naturalists who, knowing far less of the laws of inheritance than does the breeder, and knowing no more than he does of the intermediate links in the long lines of descent, yet admit that many of our domestic races are descended from the same parents--may they not learn a lesson of caution, when they deride the idea of species in a state of nature being lineal descendants of other species? PRINCIPLES OF SELECTION ANCIENTLY FOLLOWED, AND THEIR EFFECTS. Let us now briefly consider the steps by which domestic races have been produced, either from one or from several allied species. Some effect may be attributed to the direct and definite action of the external conditions of life, and some to habit; but he would be a bold man who would account by such agencies for the differences between a dray and race-horse, a greyhound and bloodhound, a carrier and tumbler pigeon. One of the most remarkable features in our domesticated races is that we see in them adaptation, not indeed to the animal's or plant's own good, but to man's use or fancy. Some variations useful to him have probably arisen suddenly, or by one step; many botanists, for instance, believe that the fuller's teasel, with its hooks, which can not be rivalled by any mechanical contrivance, is only a variety of the wild Dipsacus; and this amount of change may have suddenly arisen in a seedling. So it has probably been with the turnspit dog; and this is known to have been the case with the ancon sheep. But when we compare the dray-horse and race-horse, the dromedary and camel, the various breeds of sheep fitted either for cultivated land or mountain pasture, with the wool of one breed good for one purpose, and that of another breed for another purpose; when we compare the many breeds of dogs, each good for man in different ways; when we compare the game-cock, so pertinacious in battle, with other breeds so little quarrelsome, with "everlasting layers" which never desire to sit, and with the bantam so small and elegant; when we compare the host of agricultural, culinary, orchard, and flower-garden races of plants, most useful to man at different seasons and for different purposes, or so beautiful in his eyes, we must, I think, look further than to mere variability. We can not suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed, in many cases, we know that this has not been their history. The key is man's power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to have made for himself useful breeds. The great power of this principle of selection is not hypothetical. It is certain that several of our eminent breeders have, even within a single lifetime, modified to a large extent their breeds of cattle and sheep. In order fully to realise what they have done it is almost necessary to read several of the many treatises devoted to this subject, and to inspect the animals. Breeders habitually speak of an animal's organisation as something plastic, which they can model almost as they please. If I had space I could quote numerous passages to this effect from highly competent authorities. Youatt, who was probably better acquainted with the works of agriculturalists than almost any other individual, and who was himself a very good judge of animals, speaks of the principle of selection as "that which enables the agriculturist, not only to modify the character of his flock, but to change it altogether. It is the magician's wand, by means of which he may summon into life whatever form and mould he pleases." Lord Somerville, speaking of what breeders have done for sheep, says: "It would seem as if they had chalked out upon a wall a form perfect in itself, and then had given it existence." In Saxony the importance of the principle of selection in regard to merino sheep is so fully recognised, that men follow it as a trade: the sheep are placed on a table and are studied, like a picture by a connoisseur; this is done three times at intervals of months, and the sheep are each time marked and classed, so that the very best may ultimately be selected for breeding. What English breeders have actually effected is proved by the enormous prices given for animals with a good pedigree; and these have been exported to almost every quarter of the world. The improvement is by no means generally due to crossing different breeds; all the best breeders are strongly opposed to this practice, except sometimes among closely allied sub-breeds. And when a cross has been made, the closest selection is far more indispensable even than in ordinary cases. If selection consisted merely in separating some very distinct variety and breeding from it, the principle would be so obvious as hardly to be worth notice; but its importance consists in the great effect produced by the accumulation in one direction, during successive generations, of differences absolutely inappreciable by an uneducated eye--differences which I for one have vainly attempted to appreciate. Not one man in a thousand has accuracy of eye and judgment sufficient to become an eminent breeder. If gifted with these qualities, and he studies his subject for years, and devotes his lifetime to it with indomitable perseverance, he will succeed, and may make great improvements; if he wants any of these qualities, he will assuredly fail. Few would readily believe in the natural capacity and years of practice requisite to become even a skilful pigeon-fancier. The same principles are followed by horticulturists; but the variations are here often more abrupt. No one supposes that our choicest productions have been produced by a single variation from the aboriginal stock. We have proofs that this is not so in several cases in which exact records have been kept; thus, to give a very trifling instance, the steadily increasing size of the common gooseberry may be quoted. We see an astonishing improvement in many florists' flowers, when the flowers of the present day are compared with drawings made only twenty or thirty years ago. When a race of plants is once pretty well established, the seed-raisers do not pick out the best plants, but merely go over their seed-beds, and pull up the "rogues," as they call the plants that deviate from the proper standard. With animals this kind of selection is, in fact, likewise followed; for hardly any one is so careless as to breed from his worst animals. In regard to plants, there is another means of observing the accumulated effects of selection--namely, by comparing the diversity of flowers in the different varieties of the same species in the flower-garden; the diversity of leaves, pods, or tubers, or whatever part is valued, in the kitchen-garden, in comparison with the flowers of the same varieties; and the diversity of fruit of the same species in the orchard, in comparison with the leaves and flowers of the same set of varieties. See how different the leaves of the cabbage are, and how extremely alike the flowers; how unlike the flowers of the heartsease are, and how alike the leaves; how much the fruit of the different kinds of gooseberries differ in size, colour, shape, and hairiness, and yet the flowers present very slight differences. It is not that the varieties which differ largely in some one point do not differ at all in other points; this is hardly ever--I speak after careful observation--perhaps never, the case. The law of correlated variation, the importance of which should never be overlooked, will ensure some differences; but, as a general rule, it cannot be doubted that the continued selection of slight variations, either in the leaves, the flowers, or the fruit, will produce races differing from each other chiefly in these characters. It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three-quarters of a century; it has certainly been more attended to of late years, and many treatises have been published on the subject; and the result has been, in a corresponding degree, rapid and important. But it is very far from true that the principle is a modern discovery. I could give several references to works of high antiquity, in which the full importance of the principle is acknowledged. In rude and barbarous periods of English history choice animals were often imported, and laws were passed to prevent their exportation: the destruction of horses under a certain size was ordered, and this may be compared to the "roguing" of plants by nurserymen. The principle of selection I find distinctly given in an ancient Chinese encyclopaedia. Explicit rules are laid down by some of the Roman classical writers. From passages in Genesis, it is clear that the colour of domestic animals was at that early period attended to. Savages now sometimes cross their dogs with wild canine animals, to improve the breed, and they formerly did so, as is attested by passages in Pliny. The savages in South Africa match their draught cattle by colour, as do some of the Esquimaux their teams of dogs. Livingstone states that good domestic breeds are highly valued by the negroes in the interior of Africa who have not associated with Europeans. Some of these facts do not show actual selection, but they show that the breeding of domestic animals was carefully attended to in ancient times, and is now attended to by the lowest savages. It would, indeed, have been a strange fact, had attention not been paid to breeding, for the inheritance of good and bad qualities is so obvious. UNCONSCIOUS SELECTION. At the present time, eminent breeders try by methodical selection, with a distinct object in view, to make a new strain or sub-breed, superior to anything of the kind in the country. But, for our purpose, a form of selection, which may be called unconscious, and which results from every one trying to possess and breed from the best individual animals, is more important. Thus, a man who intends keeping pointers naturally tries to get as good dogs as he can, and afterwards breeds from his own best dogs, but he has no wish or expectation of permanently altering the breed. Nevertheless we may infer that this process, continued during centuries, would improve and modify any breed, in the same way as Bakewell, Collins, etc., by this very same process, only carried on more methodically, did greatly modify, even during their lifetimes, the forms and qualities of their cattle. Slow and insensible changes of this kind could never be recognised unless actual measurements or careful drawings of the breeds in question have been made long ago, which may serve for comparison. In some cases, however, unchanged, or but little changed, individuals of the same breed exist in less civilised districts, where the breed has been less improved. There is reason to believe that King Charles' spaniel has been unconsciously modified to a large extent since the time of that monarch. Some highly competent authorities are convinced that the setter is directly derived from the spaniel, and has probably been slowly altered from it. It is known that the English pointer has been greatly changed within the last century, and in this case the change has, it is believed, been chiefly effected by crosses with the foxhound; but what concerns us is, that the change has been effected unconsciously and gradually, and yet so effectually that, though the old Spanish pointer certainly came from Spain, Mr. Borrow has not seen, as I am informed by him, any native dog in Spain like our pointer. By a similar process of selection, and by careful training, English race-horses have come to surpass in fleetness and size the parent Arabs, so that the latter, by the regulations for the Goodwood Races, are favoured in the weights which they carry. Lord Spencer and others have shown how the cattle of England have increased in weight and in early maturity, compared with the stock formerly kept in this country. By comparing the accounts given in various old treatises of the former and present state of carrier and tumbler pigeons in Britain, India, and Persia, we can trace the stages through which they have insensibly passed, and come to differ so greatly from the rock-pigeon. Youatt gives an excellent illustration of the effects of a course of selection which may be considered as unconscious, in so far that the breeders could never have expected, or even wished, to produce the result which ensued--namely, the production of the distinct strains. The two flocks of Leicester sheep kept by Mr. Buckley and Mr. Burgess, as Mr. Youatt remarks, "Have been purely bred from the original stock of Mr. Bakewell for upwards of fifty years. There is not a suspicion existing in the mind of any one at all acquainted with the subject that the owner of either of them has deviated in any one instance from the pure blood of Mr. Bakewell's flock, and yet the difference between the sheep possessed by these two gentlemen is so great that they have the appearance of being quite different varieties." If there exist savages so barbarous as never to think of the inherited character of the offspring of their domestic animals, yet any one animal particularly useful to them, for any special purpose, would be carefully preserved during famines and other accidents, to which savages are so liable, and such choice animals would thus generally leave more offspring than the inferior ones; so that in this case there would be a kind of unconscious selection going on. We see the value set on animals even by the barbarians of Tierra del Fuego, by their killing and devouring their old women, in times of dearth, as of less value than their dogs. In plants the same gradual process of improvement through the occasional preservation of the best individuals, whether or not sufficiently distinct to be ranked at their first appearance as distinct varieties, and whether or not two or more species or races have become blended together by crossing, may plainly be recognised in the increased size and beauty which we now see in the varieties of the heartsease, rose, pelargonium, dahlia, and other plants, when compared with the older varieties or with their parent-stocks. No one would ever expect to get a first-rate heartsease or dahlia from the seed of a wild plant. No one would expect to raise a first-rate melting pear from the seed of a wild pear, though he might succeed from a poor seedling growing wild, if it had come from a garden-stock. The pear, though cultivated in classical times, appears, from Pliny's description, to have been a fruit of very inferior quality. I have seen great surprise expressed in horticultural works at the wonderful skill of gardeners in having produced such splendid results from such poor materials; but the art has been simple, and, as far as the final result is concerned, has been followed almost unconsciously. It has consisted in always cultivating the best known variety, sowing its seeds, and, when a slightly better variety chanced to appear, selecting it, and so onwards. But the gardeners of the classical period, who cultivated the best pears which they could procure, never thought what splendid fruit we should eat; though we owe our excellent fruit in some small degree to their having naturally chosen and preserved the best varieties they could anywhere find. A large amount of change, thus slowly and unconsciously accumulated, explains, as I believe, the well-known fact, that in a number of cases we cannot recognise, and therefore do not know, the wild parent-stocks of the plants which have been longest cultivated in our flower and kitchen gardens. If it has taken centuries or thousands of years to improve or modify most of our plants up to their present standard of usefulness to man, we can understand how it is that neither Australia, the Cape of Good Hope, nor any other region inhabited by quite uncivilised man, has afforded us a single plant worth culture. It is not that these countries, so rich in species, do not by a strange chance possess the aboriginal stocks of any useful plants, but that the native plants have not been improved by continued selection up to a standard of perfection comparable with that acquired by the plants in countries anciently civilised. In regard to the domestic animals kept by uncivilised man, it should not be overlooked that they almost always have to struggle for their own food, at least during certain seasons. And in two countries very differently circumstanced, individuals of the same species, having slightly different constitutions or structure, would often succeed better in the one country than in the other, and thus by a process of "natural selection," as will hereafter be more fully explained, two sub-breeds might be formed. This, perhaps, partly explains why the varieties kept by savages, as has been remarked by some authors, have more of the character of true species than the varieties kept in civilised countries. On the view here given of the important part which selection by man has played, it becomes at once obvious, how it is that our domestic races show adaptation in their structure or in their habits to man's wants or fancies. We can, I think, further understand the frequently abnormal character of our domestic races, and likewise their differences being so great in external characters, and relatively so slight in internal parts or organs. Man can hardly select, or only with much difficulty, any deviation of structure excepting such as is externally visible; and indeed he rarely cares for what is internal. He can never act by selection, excepting on variations which are first given to him in some slight degree by nature. No man would ever try to make a fantail till he saw a pigeon with a tail developed in some slight degree in an unusual manner, or a pouter till he saw a pigeon with a crop of somewhat unusual size; and the more abnormal or unusual any character was when it first appeared, the more likely it would be to catch his attention. But to use such an expression as trying to make a fantail is, I have no doubt, in most cases, utterly incorrect. The man who first selected a pigeon with a slightly larger tail, never dreamed what the descendants of that pigeon would become through long-continued, partly unconscious and partly methodical, selection. Perhaps the parent bird of all fantails had only fourteen tail-feathers somewhat expanded, like the present Java fantail, or like individuals of other and distinct breeds, in which as many as seventeen tail-feathers have been counted. Perhaps the first pouter-pigeon did not inflate its crop much more than the turbit now does the upper part of its oesophagus--a habit which is disregarded by all fanciers, as it is not one of the points of the breed. Nor let it be thought that some great deviation of structure would be necessary to catch the fancier's eye: he perceives extremely small differences, and it is in human nature to value any novelty, however slight, in one's own possession. Nor must the value which would formerly have been set on any slight differences in the individuals of the same species, be judged of by the value which is now set on them, after several breeds have fairly been established. It is known that with pigeons many slight variations now occasionally appear, but these are rejected as faults or deviations from the standard of perfection in each breed. The common goose has not given rise to any marked varieties; hence the Toulouse and the common breed, which differ only in colour, that most fleeting of characters, have lately been exhibited as distinct at our poultry-shows. These views appear to explain what has sometimes been noticed, namely, that we know hardly anything about the origin or history of any of our domestic breeds. But, in fact, a breed, like a dialect of a language, can hardly be said to have a distinct origin. A man preserves and breeds from an individual with some slight deviation of structure, or takes more care than usual in matching his best animals, and thus improves them, and the improved animals slowly spread in the immediate neighbourhood. But they will as yet hardly have a distinct name, and from being only slightly valued, their history will have been disregarded. When further improved by the same slow and gradual process, they will spread more widely, and will be recognised as something distinct and valuable, and will then probably first receive a provincial name. In semi-civilised countries, with little free communication, the spreading of a new sub-breed will be a slow process. As soon as the points of value are once acknowledged, the principle, as I have called it, of unconscious selection will always tend--perhaps more at one period than at another, as the breed rises or falls in fashion--perhaps more in one district than in another, according to the state of civilisation of the inhabitants--slowly to add to the characteristic features of the breed, whatever they may be. But the chance will be infinitely small of any record having been preserved of such slow, varying, and insensible changes. CIRCUMSTANCES FAVOURABLE TO MAN'S POWER OF SELECTION. I will now say a few words on the circumstances, favourable or the reverse, to man's power of selection. A high degree of variability is obviously favourable, as freely giving the materials for selection to work on; not that mere individual differences are not amply sufficient, with extreme care, to allow of the accumulation of a large amount of modification in almost any desired direction. But as variations manifestly useful or pleasing to man appear only occasionally, the chance of their appearance will be much increased by a large number of individuals being kept. Hence number is of the highest importance for success. On this principle Marshall formerly remarked, with respect to the sheep of part of Yorkshire, "As they generally belong to poor people, and are mostly IN SMALL LOTS, they never can be improved." On the other hand, nurserymen, from keeping large stocks of the same plant, are generally far more successful than amateurs in raising new and valuable varieties. A large number of individuals of an animal or plant can be reared only where the conditions for its propagation are favourable. When the individuals are scanty all will be allowed to breed, whatever their quality may be, and this will effectually prevent selection. But probably the most important element is that the animal or plant should be so highly valued by man, that the closest attention is paid to even the slightest deviations in its qualities or structure. Unless such attention be paid nothing can be effected. I have seen it gravely remarked, that it was most fortunate that the strawberry began to vary just when gardeners began to attend to this plant. No doubt the strawberry had always varied since it was cultivated, but the slight varieties had been neglected. As soon, however, as gardeners picked out individual plants with slightly larger, earlier, or better fruit, and raised seedlings from them, and again picked out the best seedlings and bred from them, then (with some aid by crossing distinct species) those many admirable varieties of the strawberry were raised which have appeared during the last half-century. With animals, facility in preventing crosses is an important element in the formation of new races--at least, in a country which is already stocked with other races. In this respect enclosure of the land plays a part. Wandering savages or the inhabitants of open plains rarely possess more than one breed of the same species. Pigeons can be mated for life, and this is a great convenience to the fancier, for thus many races may be improved and kept true, though mingled in the same aviary; and this circumstance must have largely favoured the formation of new breeds. Pigeons, I may add, can be propagated in great numbers and at a very quick rate, and inferior birds may be freely rejected, as when killed they serve for food. On the other hand, cats, from their nocturnal rambling habits, can not be easily matched, and, although so much valued by women and children, we rarely see a distinct breed long kept up; such breeds as we do sometimes see are almost always imported from some other country. Although I do not doubt that some domestic animals vary less than others, yet the rarity or absence of distinct breeds of the cat, the donkey, peacock, goose, etc., may be attributed in main part to selection not having been brought into play: in cats, from the difficulty in pairing them; in donkeys, from only a few being kept by poor people, and little attention paid to their breeding; for recently in certain parts of Spain and of the United States this animal has been surprisingly modified and improved by careful selection; in peacocks, from not being very easily reared and a large stock not kept; in geese, from being valuable only for two purposes, food and feathers, and more especially from no pleasure having been felt in the display of distinct breeds; but the goose, under the conditions to which it is exposed when domesticated, seems to have a singularly inflexible organisation, though it has varied to a slight extent, as I have elsewhere described. Some authors have maintained that the amount of variation in our domestic productions is soon reached, and can never afterward be exceeded. It would be somewhat rash to assert that the limit has been attained in any one case; for almost all our animals and plants have been greatly improved in many ways within a recent period; and this implies variation. It would be equally rash to assert that characters now increased to their utmost limit, could not, after remaining fixed for many centuries, again vary under new conditions of life. No doubt, as Mr. Wallace has remarked with much truth, a limit will be at last reached. For instance, there must be a limit to the fleetness of any terrestrial animal, as this will be determined by the friction to be overcome, the weight of the body to be carried, and the power of contraction in the muscular fibres. But what concerns us is that the domestic varieties of the same species differ from each other in almost every character, which man has attended to and selected, more than do the distinct species of the same genera. Isidore Geoffroy St. Hilaire has proved this in regard to size, and so it is with colour, and probably with the length of hair. With respect to fleetness, which depends on many bodily characters, Eclipse was far fleeter, and a dray-horse is comparably stronger, than any two natural species belonging to the same genus. So with plants, the seeds of the different varieties of the bean or maize probably differ more in size than do the seeds of the distinct species in any one genus in the same two families. The same remark holds good in regard to the fruit of the several varieties of the plum, and still more strongly with the melon, as well as in many other analogous cases. To sum up on the origin of our domestic races of animals and plants. Changed conditions of life are of the highest importance in causing variability, both by acting directly on the organisation, and indirectly by affecting the reproductive system. It is not probable that variability is an inherent and necessary contingent, under all circumstances. The greater or less force of inheritance and reversion determine whether variations shall endure. Variability is governed by many unknown laws, of which correlated growth is probably the most important. Something, but how much we do not know, may be attributed to the definite action of the conditions of life. Some, perhaps a great, effect may be attributed to the increased use or disuse of parts. The final result is thus rendered infinitely complex. In some cases the intercrossing of aboriginally distinct species appears to have played an important part in the origin of our breeds. When several breeds have once been formed in any country, their occasional intercrossing, with the aid of selection, has, no doubt, largely aided in the formation of new sub-breeds; but the importance of crossing has been much exaggerated, both in regard to animals and to those plants which are propagated by seed. With plants which are temporarily propagated by cuttings, buds, etc., the importance of crossing is immense; for the cultivator may here disregard the extreme variability both of hybrids and of mongrels, and the sterility of hybrids; but plants not propagated by seed are of little importance to us, for their endurance is only temporary. Over all these causes of change, the accumulative action of selection, whether applied methodically and quickly, or unconsciously and slowly, but more efficiently, seems to have been the predominant power. CHAPTER II. VARIATION UNDER NATURE. Variability--Individual differences--Doubtful species--Wide ranging, much diffused, and common species, vary most--Species of the larger genera in each country vary more frequently than the species of the smaller genera--Many of the species of the larger genera resemble varieties in being very closely, but unequally, related to each other, and in having restricted ranges. Before applying the principles arrived at in the last chapter to organic beings in a state of nature, we must briefly discuss whether these latter are subject to any variation. To treat this subject properly, a long catalogue of dry facts ought to be given; but these I shall reserve for a future work. Nor shall I here discuss the various definitions which have been given of the term species. No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species. Generally the term includes the unknown element of a distinct act of creation. The term "variety" is almost equally difficult to define; but here community of descent is almost universally implied, though it can rarely be proved. We have also what are called monstrosities; but they graduate into varieties. By a monstrosity I presume is meant some considerable deviation of structure, generally injurious, or not useful to the species. Some authors use the term "variation" in a technical sense, as implying a modification directly due to the physical conditions of life; and "variations" in this sense are supposed not to be inherited; but who can say that the dwarfed condition of shells in the brackish waters of the Baltic, or dwarfed plants on Alpine summits, or the thicker fur of an animal from far northwards, would not in some cases be inherited for at least a few generations? And in this case I presume that the form would be called a variety. It may be doubted whether sudden and considerable deviations of structure, such as we occasionally see in our domestic productions, more especially with plants, are ever permanently propagated in a state of nature. Almost every part of every organic being is so beautifully related to its complex conditions of life that it seems as improbable that any part should have been suddenly produced perfect, as that a complex machine should have been invented by man in a perfect state. Under domestication monstrosities sometimes occur which resemble normal structures in widely different animals. Thus pigs have occasionally been born with a sort of proboscis, and if any wild species of the same genus had naturally possessed a proboscis, it might have been argued that this had appeared as a monstrosity; but I have as yet failed to find, after diligent search, cases of monstrosities resembling normal structures in nearly allied forms, and these alone bear on the question. If monstrous forms of this kind ever do appear in a state of nature and are capable of reproduction (which is not always the case), as they occur rarely and singly, their preservation would depend on unusually favourable circumstances. They would, also, during the first and succeeding generations cross with the ordinary form, and thus their abnormal character would almost inevitably be lost. But I shall have to return in a future chapter to the preservation and perpetuation of single or occasional variations. INDIVIDUAL DIFFERENCES. The many slight differences which appear in the offspring from the same parents, or which it may be presumed have thus arisen, from being observed in the individuals of the same species inhabiting the same confined locality, may be called individual differences. No one supposes that all the individuals of the same species are cast in the same actual mould. These individual differences are of the highest importance for us, for they are often inherited, as must be familiar to every one; and they thus afford materials for natural selection to act on and accumulate, in the same manner as man accumulates in any given direction individual differences in his domesticated productions. These individual differences generally affect what naturalists consider unimportant parts; but I could show, by a long catalogue of facts, that parts which must be called important, whether viewed under a physiological or classificatory point of view, sometimes vary in the individuals of the same species. I am convinced that the most experienced naturalist would be surprised at the number of the cases of variability, even in important parts of structure, which he could collect on good authority, as I have collected, during a course of years. It should be remembered that systematists are far from being pleased at finding variability in important characters, and that there are not many men who will laboriously examine internal and important organs, and compare them in many specimens of the same species. It would never have been expected that the branching of the main nerves close to the great central ganglion of an insect would have been variable in the same species; it might have been thought that changes of this nature could have been effected only by slow degrees; yet Sir J. Lubbock has shown a degree of variability in these main nerves in Coccus, which may almost be compared to the irregular branching of the stem of a tree. This philosophical naturalist, I may add, has also shown that the muscles in the larvae of certain insects are far from uniform. Authors sometimes argue in a circle when they state that important organs never vary; for these same authors practically rank those parts as important (as some few naturalists have honestly confessed) which do not vary; and, under this point of view, no instance will ever be found of an important part varying; but under any other point of view many instances assuredly can be given. There is one point connected with individual differences which is extremely perplexing: I refer to those genera which have been called "protean" or "polymorphic," in which species present an inordinate amount of variation. With respect to many of these forms, hardly two naturalists agree whether to rank them as species or as varieties. We may instance Rubus, Rosa, and Hieracium among plants, several genera of insects, and of Brachiopod shells. In most polymorphic genera some of the species have fixed and definite characters. Genera which are polymorphic in one country seem to be, with a few exceptions, polymorphic in other countries, and likewise, judging from Brachiopod shells, at former periods of time. These facts are very perplexing, for they seem to show that this kind of variability is independent of the conditions of life. I am inclined to suspect that we see, at least in some of these polymorphic genera, variations which are of no service or disservice to the species, and which consequently have not been seized on and rendered definite by natural selection, as hereafter to be explained. Individuals of the same species often present, as is known to every one, great differences of structure, independently of variation, as in the two sexes of various animals, in the two or three castes of sterile females or workers among insects, and in the immature and larval states of many of the lower animals. There are, also, cases of dimorphism and trimorphism, both with animals and plants. Thus, Mr. Wallace, who has lately called attention to the subject, has shown that the females of certain species of butterflies, in the Malayan Archipelago, regularly appear under two or even three conspicuously distinct forms, not connected by intermediate varieties. Fritz Muller has described analogous but more extraordinary cases with the males of certain Brazilian Crustaceans: thus, the male of a Tanais regularly occurs under two distinct forms; one of these has strong and differently shaped pincers, and the other has antennae much more abundantly furnished with smelling-hairs. Although in most of these cases, the two or three forms, both with animals and plants, are not now connected by intermediate gradations, it is possible that they were once thus connected. Mr. Wallace, for instance, describes a certain butterfly which presents in the same island a great range of varieties connected by intermediate links, and the extreme links of the chain closely resemble the two forms of an allied dimorphic species inhabiting another part of the Malay Archipelago. Thus also with ants, the several worker-castes are generally quite distinct; but in some cases, as we shall hereafter see, the castes are connected together by finely graduated varieties. So it is, as I have myself observed, with some dimorphic plants. It certainly at first appears a highly remarkable fact that the same female butterfly should have the power of producing at the same time three distinct female forms and a male; and that an hermaphrodite plant should produce from the same seed-capsule three distinct hermaphrodite forms, bearing three different kinds of females and three or even six different kinds of males. Nevertheless these cases are only exaggerations of the common fact that the female produces offspring of two sexes which sometimes differ from each other in a wonderful manner. DOUBTFUL SPECIES. The forms which possess in some considerable degree the character of species, but which are so closely similar to other forms, or are so closely linked to them by intermediate gradations, that naturalists do not like to rank them as distinct species, are in several respects the most important for us. We have every reason to believe that many of these doubtful and closely allied forms have permanently retained their characters for a long time; for as long, as far as we know, as have good and true species. Practically, when a naturalist can unite by means of intermediate links any two forms, he treats the one as a variety of the other, ranking the most common, but sometimes the one first described as the species, and the other as the variety. But cases of great difficulty, which I will not here enumerate, sometimes arise in deciding whether or not to rank one form as a variety of another, even when they are closely connected by intermediate links; nor will the commonly assumed hybrid nature of the intermediate forms always remove the difficulty. In very many cases, however, one form is ranked as a variety of another, not because the intermediate links have actually been found, but because analogy leads the observer to suppose either that they do now somewhere exist, or may formerly have existed; and here a wide door for the entry of doubt and conjecture is opened. Hence, in determining whether a form should be ranked as a species or a variety, the opinion of naturalists having sound judgment and wide experience seems the only guide to follow. We must, however, in many cases, decide by a majority of naturalists, for few well-marked and well-known varieties can be named which have not been ranked as species by at least some competent judges. That varieties of this doubtful nature are far from uncommon cannot be disputed. Compare the several floras of Great Britain, of France, or of the United States, drawn up by different botanists, and see what a surprising number of forms have been ranked by one botanist as good species, and by another as mere varieties. Mr. H.C. Watson, to whom I lie under deep obligation for assistance of all kinds, has marked for me 182 British plants, which are generally considered as varieties, but which have all been ranked by botanists as species; and in making this list he has omitted many trifling varieties, but which nevertheless have been ranked by some botanists as species, and he has entirely omitted several highly polymorphic genera. Under genera, including the most polymorphic forms, Mr. Babington gives 251 species, whereas Mr. Bentham gives only 112--a difference of 139 doubtful forms! Among animals which unite for each birth, and which are highly locomotive, doubtful forms, ranked by one zoologist as a species and by another as a variety, can rarely be found within the same country, but are common in separated areas. How many of the birds and insects in North America and Europe, which differ very slightly from each other, have been ranked by one eminent naturalist as undoubted species, and by another as varieties, or, as they are often called, geographical races! Mr. Wallace, in several valuable papers on the various animals, especially on the Lepidoptera, inhabiting the islands of the great Malayan Archipelago, shows that they may be classed under four heads, namely, as variable forms, as local forms, as geographical races or sub-species, and as true representative species. The first or variable forms vary much within the limits of the same island. The local forms are moderately constant and distinct in each separate island; but when all from the several islands are compared together, the differences are seen to be so slight and graduated that it is impossible to define or describe them, though at the same time the extreme forms are sufficiently distinct. The geographical races or sub-species are local forms completely fixed and isolated; but as they do not differ from each other by strongly marked and important characters, "There is no possible test but individual opinion to determine which of them shall be considered as species and which as varieties." Lastly, representative species fill the same place in the natural economy of each island as do the local forms and sub-species; but as they are distinguished from each other by a greater amount of difference than that between the local forms and sub-species, they are almost universally ranked by naturalists as true species. Nevertheless, no certain criterion can possibly be given by which variable forms, local forms, sub species and representative species can be recognised. Many years ago, when comparing, and seeing others compare, the birds from the closely neighbouring islands of the Galapagos Archipelago, one with another, and with those from the American mainland, I was much struck how entirely vague and arbitrary is the distinction between species and varieties. On the islets of the little Madeira group there are many insects which are characterized as varieties in Mr. Wollaston's admirable work, but which would certainly be ranked as distinct species by many entomologists. Even Ireland has a few animals, now generally regarded as varieties, but which have been ranked as species by some zoologists. Several experienced ornithologists consider our British red grouse as only a strongly marked race of a Norwegian species, whereas the greater number rank it as an undoubted species peculiar to Great Britain. A wide distance between the homes of two doubtful forms leads many naturalists to rank them as distinct species; but what distance, it has been well asked, will suffice if that between America and Europe is ample, will that between Europe and the Azores, or Madeira, or the Canaries, or between the several islets of these small archipelagos, be sufficient? Mr. B.D. Walsh, a distinguished entomologist of the United States, has described what he calls Phytophagic varieties and Phytophagic species. Most vegetable-feeding insects live on one kind of plant or on one group of plants; some feed indiscriminately on many kinds, but do not in consequence vary. In several cases, however, insects found living on different plants, have been observed by Mr. Walsh to present in their larval or mature state, or in both states, slight, though constant differences in colour, size, or in the nature of their secretions. In some instances the males alone, in other instances, both males and females, have been observed thus to differ in a slight degree. When the differences are rather more strongly marked, and when both sexes and all ages are affected, the forms are ranked by all entomologists as good species. But no observer can determine for another, even if he can do so for himself, which of these Phytophagic forms ought to be called species and which varieties. Mr. Walsh ranks the forms which it may be supposed would freely intercross, as varieties; and those which appear to have lost this power, as species. As the differences depend on the insects having long fed on distinct plants, it cannot be expected that intermediate links connecting the several forms should now be found. The naturalist thus loses his best guide in determining whether to rank doubtful forms as varieties or species. This likewise necessarily occurs with closely allied organisms, which inhabit distinct continents or islands. When, on the other hand, an animal or plant ranges over the same continent, or inhabits many islands in the same archipelago, and presents different forms in the different areas, there is always a good chance that intermediate forms will be discovered which will link together the extreme states; and these are then degraded to the rank of varieties. Some few naturalists maintain that animals never present varieties; but then these same naturalists rank the slightest difference as of specific value; and when the same identical form is met with in two distant countries, or in two geological formations, they believe that two distinct species are hidden under the same dress. The term species thus comes to be a mere useless abstraction, implying and assuming a separate act of creation. It is certain that many forms, considered by highly competent judges to be varieties, resemble species so completely in character that they have been thus ranked by other highly competent judges. But to discuss whether they ought to be called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air. Many of the cases of strongly marked varieties or doubtful species well deserve consideration; for several interesting lines of argument, from geographical distribution, analogical variation, hybridism, etc., have been brought to bear in the attempt to determine their rank; but space does not here permit me to discuss them. Close investigation, in many cases, will no doubt bring naturalists to agree how to rank doubtful forms. Yet it must be confessed that it is in the best known countries that we find the greatest number of them. I have been struck with the fact that if any animal or plant in a state of nature be highly useful to man, or from any cause closely attracts his attention, varieties of it will almost universally be found recorded. These varieties, moreover, will often be ranked by some authors as species. Look at the common oak, how closely it has been studied; yet a German author makes more than a dozen species out of forms, which are almost universally considered by other botanists to be varieties; and in this country the highest botanical authorities and practical men can be quoted to show that the sessile and pedunculated oaks are either good and distinct species or mere varieties. I may here allude to a remarkable memoir lately published by A. de Candolle, on the oaks of the whole world. No one ever had more ample materials for the discrimination of the species, or could have worked on them with more zeal and sagacity. He first gives in detail all the many points of structure which vary in the several species, and estimates numerically the relative frequency of the variations. He specifies above a dozen characters which may be found varying even on the same branch, sometimes according to age or development, sometimes without any assignable reason. Such characters are not of course of specific value, but they are, as Asa Gray has remarked in commenting on this memoir, such as generally enter into specific definitions. De Candolle then goes on to say that he gives the rank of species to the forms that differ by characters never varying on the same tree, and never found connected by intermediate states. After this discussion, the result of so much labour, he emphatically remarks: "They are mistaken, who repeat that the greater part of our species are clearly limited, and that the doubtful species are in a feeble minority. This seemed to be true, so long as a genus was imperfectly known, and its species were founded upon a few specimens, that is to say, were provisional. Just as we come to know them better, intermediate forms flow in, and doubts as to specific limits augment." He also adds that it is the best known species which present the greatest number of spontaneous varieties and sub-varieties. Thus Quercus robur has twenty-eight varieties, all of which, excepting six, are clustered round three sub-species, namely Q. pedunculata, sessiliflora and pubescens. The forms which connect these three sub-species are comparatively rare; and, as Asa Gray again remarks, if these connecting forms which are now rare were to become totally extinct the three sub-species would hold exactly the same relation to each other as do the four or five provisionally admitted species which closely surround the typical Quercus robur. Finally, De Candolle admits that out of the 300 species, which will be enumerated in his Prodromus as belonging to the oak family, at least two-thirds are provisional species, that is, are not known strictly to fulfil the definition above given of a true species. It should be added that De Candolle no longer believes that species are immutable creations, but concludes that the derivative theory is the most natural one, "and the most accordant with the known facts in palaeontology, geographical botany and zoology, of anatomical structure and classification." When a young naturalist commences the study of a group of organisms quite unknown to him he is at first much perplexed in determining what differences to consider as specific and what as varietal; for he knows nothing of the amount and kind of variation to which the group is subject; and this shows, at least, how very generally there is some variation. But if he confine his attention to one class within one country he will soon make up his mind how to rank most of the doubtful forms. His general tendency will be to make many species, for he will become impressed, just like the pigeon or poultry fancier before alluded to, with the amount of difference in the forms which he is continually studying; and he has little general knowledge of analogical variation in other groups and in other countries by which to correct his first impressions. As he extends the range of his observations he will meet with more cases of difficulty; for he will encounter a greater number of closely-allied forms. But if his observations be widely extended he will in the end generally be able to make up his own mind; but he will succeed in this at the expense of admitting much variation, and the truth of this admission will often be disputed by other naturalists. When he comes to study allied forms brought from countries not now continuous, in which case he cannot hope to find intermediate links, he will be compelled to trust almost entirely to analogy, and his difficulties will rise to a climax. Certainly no clear line of demarcation has as yet been drawn between species and sub-species--that is, the forms which in the opinion of some naturalists come very near to, but do not quite arrive at, the rank of species; or, again, between sub-species and well-marked varieties, or between lesser varieties and individual differences. These differences blend into each other by an insensible series; and a series impresses the mind with the idea of an actual passage. Hence I look at individual differences, though of small interest to the systematist, as of the highest importance for us, as being the first step towards such slight varieties as are barely thought worth recording in works on natural history. And I look at varieties which are in any degree more distinct and permanent, as steps toward more strongly marked and permanent varieties; and at the latter, as leading to sub-species, and then to species. The passage from one stage of difference to another may, in many cases, be the simple result of the nature of the organism and of the different physical conditions to which it has long been exposed; but with respect to the more important and adaptive characters, the passage from one stage of difference to another may be safely attributed to the cumulative action of natural selection, hereafter to be explained, and to the effects of the increased use or disuse of parts. A well-marked variety may therefore be called an incipient species; but whether this belief is justifiable must be judged by the weight of the various facts and considerations to be given throughout this work. It need not be supposed that all varieties or incipient species attain the rank of species. They may become extinct, or they may endure as varieties for very long periods, as has been shown to be the case by Mr. Wollaston with the varieties of certain fossil land-shells in Madeira, and with plants by Gaston de Saporta. If a variety were to flourish so as to exceed in numbers the parent species, it would then rank as the species, and the species as the variety; or it might come to supplant and exterminate the parent species; or both might co-exist, and both rank as independent species. But we shall hereafter return to this subject. From these remarks it will be seen that I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety, which is given to less distinct and more fluctuating forms. The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, for convenience sake. WIDE-RANGING, MUCH DIFFUSED, AND COMMON SPECIES VARY MOST. Guided by theoretical considerations, I thought that some interesting results might be obtained in regard to the nature and relations of the species which vary most, by tabulating all the varieties in several well-worked floras. At first this seemed a simple task; but Mr. H.C. Watson, to whom I am much indebted for valuable advice and assistance on this subject, soon convinced me that there were many difficulties, as did subsequently Dr. Hooker, even in stronger terms. I shall reserve for a future work the discussion of these difficulties, and the tables of the proportional numbers of the varying species. Dr. Hooker permits me to add that after having carefully read my manuscript, and examined the tables, he thinks that the following statements are fairly well established. The whole subject, however, treated as it necessarily here is with much brevity, is rather perplexing, and allusions cannot be avoided to the "struggle for existence," "divergence of character," and other questions, hereafter to be discussed. Alphonse de Candolle and others have shown that plants which have very wide ranges generally present varieties; and this might have been expected, as they are exposed to diverse physical conditions, and as they come into competition (which, as we shall hereafter see, is a far more important circumstance) with different sets of organic beings. But my tables further show that, in any limited country, the species which are the most common, that is abound most in individuals, and the species which are most widely diffused within their own country (and this is a different consideration from wide range, and to a certain extent from commonness), oftenest give rise to varieties sufficiently well-marked to have been recorded in botanical works. Hence it is the most flourishing, or, as they may be called, the dominant species--those which range widely, are the most diffused in their own country, and are the most numerous in individuals--which oftenest produce well-marked varieties, or, as I consider them, incipient species. And this, perhaps, might have been anticipated; for, as varieties, in order to become in any degree permanent, necessarily have to struggle with the other inhabitants of the country, the species which are already dominant will be the most likely to yield offspring, which, though in some slight degree modified, still inherit those advantages that enabled their parents to become dominant over their compatriots. In these remarks on predominence, it should be understood that reference is made only to the forms which come into competition with each other, and more especially to the members of the same genus or class having nearly similar habits of life. With respect to the number of individuals or commonness of species, the comparison of course relates only to the members of the same group. One of the higher plants may be said to be dominant if it be more numerous in individuals and more widely diffused than the other plants of the same country, which live under nearly the same conditions. A plant of this kind is not the less dominant because some conferva inhabiting the water or some parasitic fungus is infinitely more numerous in individuals, and more widely diffused. But if the conferva or parasitic fungus exceeds its allies in the above respects, it will then be dominant within its own class. SPECIES OF THE LARGER GENERA IN EACH COUNTRY VARY MORE FREQUENTLY THAN THE SPECIES OF THE SMALLER GENERA. If the plants inhabiting a country as described in any Flora, be divided into two equal masses, all those in the larger genera (i.e., those including many species) being placed on one side, and all those in the smaller genera on the other side, the former will be found to include a somewhat larger number of the very common and much diffused or dominant species. This might have been anticipated, for the mere fact of many species of the same genus inhabiting any country, shows that there is something in the organic or inorganic conditions of that country favourable to the genus; and, consequently, we might have expected to have found in the larger genera, or those including many species, a larger proportional number of dominant species. But so many causes tend to obscure this result, that I am surprised that my tables show even a small majority on the side of the larger genera. I will here allude to only two causes of obscurity. Fresh water and salt-loving plants generally have very wide ranges and are much diffused, but this seems to be connected with the nature of the stations inhabited by them, and has little or no relation to the size of the genera to which the species belong. Again, plants low in the scale of organisation are generally much more widely diffused than plants higher in the scale; and here again there is no close relation to the size of the genera. The cause of lowly-organised plants ranging widely will be discussed in our chapter on Geographical Distribution. From looking at species as only strongly marked and well-defined varieties, I was led to anticipate that the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera; for wherever many closely related species (i.e., species of the same genus) have been formed, many varieties or incipient species ought, as a general rule, to be now forming. Where many large trees grow, we expect to find saplings. Where many species of a genus have been formed through variation, circumstances have been favourable for variation; and hence we might expect that the circumstances would generally still be favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group having many species, than in one having few. To test the truth of this anticipation I have arranged the plants of twelve countries, and the coleopterous insects of two districts, into two nearly equal masses, the species of the larger genera on one side, and those of the smaller genera on the other side, and it has invariably proved to be the case that a larger proportion of the species on the side of the larger genera presented varieties, than on the side of the smaller genera. Moreover, the species of the large genera which present any varieties, invariably present a larger average number of varieties than do the species of the small genera. Both these results follow when another division is made, and when all the least genera, with from only one to four species, are altogether excluded from the tables. These facts are of plain signification on the view that species are only strongly marked and permanent varieties; for wherever many species of the same genus have been formed, or where, if we may use the expression, the manufactory of species has been active, we ought generally to find the manufactory still in action, more especially as we have every reason to believe the process of manufacturing new species to be a slow one. And this certainly holds true if varieties be looked at as incipient species; for my tables clearly show, as a general rule, that, wherever many species of a genus have been formed, the species of that genus present a number of varieties, that is, of incipient species, beyond the average. It is not that all large genera are now varying much, and are thus increasing in the number of their species, or that no small genera are now varying and increasing; for if this had been so, it would have been fatal to my theory; inasmuch as geology plainly tells us that small genera have in the lapse of time often increased greatly in size; and that large genera have often come to their maxima, declined, and disappeared. All that we want to show is, that where many species of a genus have been formed, on an average many are still forming; and this certainly holds good. MANY OF THE SPECIES INCLUDED WITHIN THE LARGER GENERA RESEMBLE VARIETIES IN BEING VERY CLOSELY, BUT UNEQUALLY, RELATED TO EACH OTHER, AND IN HAVING RESTRICTED RANGES. There are other relations between the species of large genera and their recorded varieties which deserve notice. We have seen that there is no infallible criterion by which to distinguish species and well-marked varieties; and when intermediate links have not been found between doubtful forms, naturalists are compelled to come to a determination by the amount of difference between them, judging by analogy whether or not the amount suffices to raise one or both to the rank of species. Hence the amount of difference is one very important criterion in settling whether two forms should be ranked as species or varieties. Now Fries has remarked in regard to plants, and Westwood in regard to insects, that in large genera the amount of difference between the species is often exceedingly small. I have endeavoured to test this numerically by averages, and, as far as my imperfect results go, they confirm the view. I have also consulted some sagacious and experienced observers, and, after deliberation, they concur in this view. In this respect, therefore, the species of the larger genera resemble varieties, more than do the species of the smaller genera. Or the case may be put in another way, and it may be said, that in the larger genera, in which a number of varieties or incipient species greater than the average are now manufacturing, many of the species already manufactured still to a certain extent resemble varieties, for they differ from each other by a less than the usual amount of difference. Moreover, the species of the larger genera are related to each other, in the same manner as the varieties of any one species are related to each other. No naturalist pretends that all the species of a genus are equally distinct from each other; they may generally be divided into sub-genera, or sections, or lesser groups. As Fries has well remarked, little groups of species are generally clustered like satellites around other species. And what are varieties but groups of forms, unequally related to each other, and clustered round certain forms--that is, round their parent-species. Undoubtedly there is one most important point of difference between varieties and species, namely, that the amount of difference between varieties, when compared with each other or with their parent-species, is much less than that between the species of the same genus. But when we come to discuss the principle, as I call it, of divergence of character, we shall see how this may be explained, and how the lesser differences between varieties tend to increase into the greater differences between species. There is one other point which is worth notice. Varieties generally have much restricted ranges. This statement is indeed scarcely more than a truism, for if a variety were found to have a wider range than that of its supposed parent-species, their denominations would be reversed. But there is reason to believe that the species which are very closely allied to other species, and in so far resemble varieties, often have much restricted ranges. For instance, Mr. H.C. Watson has marked for me in the well-sifted London catalogue of Plants (4th edition) sixty-three plants which are therein ranked as species, but which he considers as so closely allied to other species as to be of doubtful value: these sixty-three reputed species range on an average over 6.9 of the provinces into which Mr. Watson has divided Great Britain. Now, in this same catalogue, fifty-three acknowledged varieties are recorded, and these range over 7.7 provinces; whereas, the species to which these varieties belong range over 14.3 provinces. So that the acknowledged varieties have very nearly the same restricted average range, as have the closely allied forms, marked for me by Mr. Watson as doubtful species, but which are almost universally ranked by British botanists as good and true species. SUMMARY. Finally, varieties cannot be distinguished from species--except, first, by the discovery of intermediate linking forms; and, secondly, by a certain indefinite amount of difference between them; for two forms, if differing very little, are generally ranked as varieties, notwithstanding that they cannot be closely connected; but the amount of difference considered necessary to give to any two forms the rank of species cannot be defined. In genera having more than the average number of species in any country, the species of these genera have more than the average number of varieties. In large genera the species are apt to be closely but unequally allied together, forming little clusters round other species. Species very closely allied to other species apparently have restricted ranges. In all these respects the species of large genera present a strong analogy with varieties. And we can clearly understand these analogies, if species once existed as varieties, and thus originated; whereas, these analogies are utterly inexplicable if species are independent creations. We have also seen that it is the most flourishing or dominant species of the larger genera within each class which on an average yield the greatest number of varieties, and varieties, as we shall hereafter see, tend to become converted into new and distinct species. Thus the larger genera tend to become larger; and throughout nature the forms of life which are now dominant tend to become still more dominant by leaving many modified and dominant descendants. But, by steps hereafter to be explained, the larger genera also tend to break up into smaller genera. And thus, the forms of life throughout the universe become divided into groups subordinate to groups. CHAPTER III. STRUGGLE FOR EXISTENCE. Its bearing on natural selection--The term used in a wide sense--Geometrical ratio of increase--Rapid increase of naturalised animals and plants--Nature of the checks to increase--Competition universal--Effects of climate--Protection from the number of individuals--Complex relations of all animals and plants throughout nature--Struggle for life most severe between individuals and varieties of the same species: often severe between species of the same genus--The relation of organism to organism the most important of all relations. Before entering on the subject of this chapter I must make a few preliminary remarks to show how the struggle for existence bears on natural selection. It has been seen in the last chapter that among organic beings in a state of nature there is some individual variability: indeed I am not aware that this has ever been disputed. It is immaterial for us whether a multitude of doubtful forms be called species or sub-species or varieties; what rank, for instance, the two or three hundred doubtful forms of British plants are entitled to hold, if the existence of any well-marked varieties be admitted. But the mere existence of individual variability and of some few well-marked varieties, though necessary as the foundation for the work, helps us but little in understanding how species arise in nature. How have all those exquisite adaptations of one part of the organisation to another part, and to the conditions of life and of one organic being to another being, been perfected? We see these beautiful co-adaptations most plainly in the woodpecker and the mistletoe; and only a little less plainly in the humblest parasite which clings to the hairs of a quadruped or feathers of a bird; in the structure of the beetle which dives through the water; in the plumed seed which is wafted by the gentlest breeze; in short, we see beautiful adaptations everywhere and in every part of the organic world. Again, it may be asked, how is it that varieties, which I have called incipient species, become ultimately converted into good and distinct species, which in most cases obviously differ from each other far more than do the varieties of the same species? How do those groups of species, which constitute what are called distinct genera and which differ from each other more than do the species of the same genus, arise? All these results, as we shall more fully see in the next chapter, follow from the struggle for life. Owing to this struggle, variations, however slight and from whatever cause proceeding, if they be in any degree profitable to the individuals of a species, in their infinitely complex relations to other organic beings and to their physical conditions of life, will tend to the preservation of such individuals, and will generally be inherited by the offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term natural selection, in order to mark its relation to man's power of selection. But the expression often used by Mr. Herbert Spencer, of the Survival of the Fittest, is more accurate, and is sometimes equally convenient. We have seen that man by selection can certainly produce great results, and can adapt organic beings to his own uses, through the accumulation of slight but useful variations, given to him by the hand of Nature. But Natural Selection, we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man's feeble efforts, as the works of Nature are to those of Art. We will now discuss in a little more detail the struggle for existence. In my future work this subject will be treated, as it well deserves, at greater length. The elder De Candolle and Lyell have largely and philosophically shown that all organic beings are exposed to severe competition. In regard to plants, no one has treated this subject with more spirit and ability than W. Herbert, Dean of Manchester, evidently the result of his great horticultural knowledge. Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult--at least I found it so--than constantly to bear this conclusion in mind. Yet unless it be thoroughly engrained in the mind, the whole economy of nature, with every fact on distribution, rarity, abundance, extinction, and variation, will be dimly seen or quite misunderstood. We behold the face of nature bright with gladness, we often see superabundance of food; we do not see or we forget that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that, though food may be now superabundant, it is not so at all seasons of each recurring year. THE TERM, STRUGGLE FOR EXISTENCE, USED IN A LARGE SENSE. I should premise that I use this term in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny. Two canine animals, in a time of dearth, may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture. A plant which annually produces a thousand seeds, of which only one of an average comes to maturity, may be more truly said to struggle with the plants of the same and other kinds which already clothe the ground. The mistletoe is dependent on the apple and a few other trees, but can only in a far-fetched sense be said to struggle with these trees, for, if too many of these parasites grow on the same tree, it languishes and dies. But several seedling mistletoes, growing close together on the same branch, may more truly be said to struggle with each other. As the mistletoe is disseminated by birds, its existence depends on them; and it may metaphorically be said to struggle with other fruit-bearing plants, in tempting the birds to devour and thus disseminate its seeds. In these several senses, which pass into each other, I use for convenience sake the general term of Struggle for Existence. GEOMETRICAL RATIO OF INCREASE. A struggle for existence inevitably follows from the high rate at which all organic beings tend to increase. Every being, which during its natural lifetime produces several eggs or seeds, must suffer destruction during some period of its life, and during some season or occasional year, otherwise, on the principle of geometrical increase, its numbers would quickly become so inordinately great that no country could support the product. Hence, as more individuals are produced than can possibly survive, there must in every case be a struggle for existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life. It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms; for in this case there can be no artificial increase of food, and no prudential restraint from marriage. Although some species may be now increasing, more or less rapidly, in numbers, all cannot do so, for the world would not hold them. There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in less than a thousand years, there would literally not be standing room for his progeny. Linnaeus has calculated that if an annual plant produced only two seeds--and there is no plant so unproductive as this--and their seedlings next year produced two, and so on, then in twenty years there would be a million plants. The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase; it will be safest to assume that it begins breeding when thirty years old, and goes on breeding till ninety years old, bringing forth six young in the interval, and surviving till one hundred years old; if this be so, after a period of from 740 to 750 years there would be nearly nineteen million elephants alive descended from the first pair. But we have better evidence on this subject than mere theoretical calculations, namely, the numerous recorded cases of the astonishingly rapid increase of various animals in a state of nature, when circumstances have been favourable to them during two or three following seasons. Still more striking is the evidence from our domestic animals of many kinds which have run wild in several parts of the world; if the statements of the rate of increase of slow-breeding cattle and horses in South America, and latterly in Australia, had not been well authenticated, they would have been incredible. So it is with plants; cases could be given of introduced plants which have become common throughout whole islands in a period of less than ten years. Several of the plants, such as the cardoon and a tall thistle, which are now the commonest over the wide plains of La Plata, clothing square leagues of surface almost to the exclusion of every other plant, have been introduced from Europe; and there are plants which now range in India, as I hear from Dr. Falconer, from Cape Comorin to the Himalaya, which have been imported from America since its discovery. In such cases, and endless others could be given, no one supposes that the fertility of the animals or plants has been suddenly and temporarily increased in any sensible degree. The obvious explanation is that the conditions of life have been highly favourable, and that there has consequently been less destruction of the old and young and that nearly all the young have been enabled to breed. Their geometrical ratio of increase, the result of which never fails to be surprising, simply explains their extraordinarily rapid increase and wide diffusion in their new homes. In a state of nature almost every full-grown plant annually produces seed, and among animals there are very few which do not annually pair. Hence we may confidently assert that all plants and animals are tending to increase at a geometrical ratio--that all would rapidly stock every station in which they could any how exist, and that this geometrical tendency to increase must be checked by destruction at some period of life. Our familiarity with the larger domestic animals tends, I think, to mislead us; we see no great destruction falling on them, and we do not keep in mind that thousands are annually slaughtered for food, and that in a state of nature an equal number would have somehow to be disposed of. The only difference between organisms which annually produce eggs or seeds by the thousand, and those which produce extremely few, is, that the slow breeders would require a few more years to people, under favourable conditions, a whole district, let it be ever so large. The condor lays a couple of eggs and the ostrich a score, and yet in the same country the condor may be the more numerous of the two. The Fulmar petrel lays but one egg, yet it is believed to be the most numerous bird in the world. One fly deposits hundreds of eggs, and another, like the hippobosca, a single one. But this difference does not determine how many individuals of the two species can be supported in a district. A large number of eggs is of some importance to those species which depend on a fluctuating amount of food, for it allows them rapidly to increase in number. But the real importance of a large number of eggs or seeds is to make up for much destruction at some period of life; and this period in the great majority of cases is an early one. If an animal can in any way protect its own eggs or young, a small number may be produced, and yet the average stock be fully kept up; but if many eggs or young are destroyed, many must be produced or the species will become extinct. It would suffice to keep up the full number of a tree, which lived on an average for a thousand years, if a single seed were produced once in a thousand years, supposing that this seed were never destroyed and could be ensured to germinate in a fitting place; so that, in all cases, the average number of any animal or plant depends only indirectly on the number of its eggs or seeds. In looking at Nature, it is most necessary to keep the foregoing considerations always in mind--never to forget that every single organic being may be said to be striving to the utmost to increase in numbers; that each lives by a struggle at some period of its life; that heavy destruction inevitably falls either on the young or old during each generation or at recurrent intervals. Lighten any check, mitigate the destruction ever so little, and the number of the species will almost instantaneously increase to any amount. NATURE OF THE CHECKS TO INCREASE. The causes which check the natural tendency of each species to increase are most obscure. Look at the most vigorous species; by as much as it swarms in numbers, by so much will it tend to increase still further. We know not exactly what the checks are even in a single instance. Nor will this surprise any one who reflects how ignorant we are on this head, even in regard to mankind, although so incomparably better known than any other animal. This subject of the checks to increase has been ably treated by several authors, and I hope in a future work to discuss it at considerable length, more especially in regard to the feral animals of South America. Here I will make only a few remarks, just to recall to the reader's mind some of the chief points. Eggs or very young animals seem generally to suffer most, but this is not invariably the case. With plants there is a vast destruction of seeds, but from some observations which I have made it appears that the seedlings suffer most from germinating in ground already thickly stocked with other plants. Seedlings, also, are destroyed in vast numbers by various enemies; for instance, on a piece of ground three feet long and two wide, dug and cleared, and where there could be no choking from other plants, I marked all the seedlings of our native weeds as they came up, and out of 357 no less than 295 were destroyed, chiefly by slugs and insects. If turf which has long been mown, and the case would be the same with turf closely browsed by quadrupeds, be let to grow, the more vigorous plants gradually kill the less vigorous, though fully grown plants; thus out of twenty species grown on a little plot of mown turf (three feet by four) nine species perished, from the other species being allowed to grow up freely. The amount of food for each species, of course, gives the extreme limit to which each can increase; but very frequently it is not the obtaining food, but the serving as prey to other animals, which determines the average number of a species. Thus, there seems to be little doubt that the stock of partridges, grouse, and hares on any large estate depends chiefly on the destruction of vermin. If not one head of game were shot during the next twenty years in England, and, at the same time, if no vermin were destroyed, there would, in all probability, be less game than at present, although hundreds of thousands of game animals are now annually shot. On the other hand, in some cases, as with the elephant, none are destroyed by beasts of prey; for even the tiger in India most rarely dares to attack a young elephant protected by its dam. Climate plays an important part in determining the average numbers of a species, and periodical seasons of extreme cold or drought seem to be the most effective of all checks. I estimated (chiefly from the greatly reduced numbers of nests in the spring) that the winter of 1854-5 destroyed four-fifths of the birds in my own grounds; and this is a tremendous destruction, when we remember that ten per cent. is an extraordinarily severe mortality from epidemics with man. The action of climate seems at first sight to be quite independent of the struggle for existence; but in so far as climate chiefly acts in reducing food, it brings on the most severe struggle between the individuals, whether of the same or of distinct species, which subsist on the same kind of food. Even when climate, for instance, extreme cold, acts directly, it will be the least vigorous individuals, or those which have got least food through the advancing winter, which will suffer the most. When we travel from south to north, or from a damp region to a dry, we invariably see some species gradually getting rarer and rarer, and finally disappearing; and the change of climate being conspicuous, we are tempted to attribute the whole effect to its direct action. But this is a false view; we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food; and if these enemies or competitors be in the least degree favoured by any slight change of climate, they will increase in numbers; and as each area is already fully stocked with inhabitants, the other species must decrease. When we travel southward and see a species decreasing in numbers, we may feel sure that the cause lies quite as much in other species being favoured, as in this one being hurt. So it is when we travel northward, but in a somewhat lesser degree, for the number of species of all kinds, and therefore of competitors, decreases northward; hence in going northward, or in ascending a mountain, we far oftener meet with stunted forms, due to the DIRECTLY injurious action of climate, than we do in proceeding southward or in descending a mountain. When we reach the Arctic regions, or snow-capped summits, or absolute deserts, the struggle for life is almost exclusively with the elements. That climate acts in main part indirectly by favouring other species we clearly see in the prodigious number of plants which in our gardens can perfectly well endure our climate, but which never become naturalised, for they cannot compete with our native plants nor resist destruction by our native animals. When a species, owing to highly favourable circumstances, increases inordinately in numbers in a small tract, epidemics--at least, this seems generally to occur with our game animals--often ensue; and here we have a limiting check independent of the struggle for life. But even some of these so-called epidemics appear to be due to parasitic worms, which have from some cause, possibly in part through facility of diffusion among the crowded animals, been disproportionally favoured: and here comes in a sort of struggle between the parasite and its prey. On the other hand, in many cases, a large stock of individuals of the same species, relatively to the numbers of its enemies, is absolutely necessary for its preservation. Thus we can easily raise plenty of corn and rape-seed, etc., in our fields, because the seeds are in great excess compared with the number of birds which feed on them; nor can the birds, though having a superabundance of food at this one season, increase in number proportionally to the supply of seed, as their numbers are checked during the winter; but any one who has tried knows how troublesome it is to get seed from a few wheat or other such plants in a garden; I have in this case lost every single seed. This view of the necessity of a large stock of the same species for its preservation, explains, I believe, some singular facts in nature such as that of very rare plants being sometimes extremely abundant, in the few spots where they do exist; and that of some social plants being social, that is abounding in individuals, even on the extreme verge of their range. For in such cases, we may believe, that a plant could exist only where the conditions of its life were so favourable that many could exist together, and thus save the species from utter destruction. I should add that the good effects of intercrossing, and the ill effects of close interbreeding, no doubt come into play in many of these cases; but I will not here enlarge on this subject. COMPLEX RELATIONS OF ALL ANIMALS AND PLANTS TO EACH OTHER IN THE STRUGGLE FOR EXISTENCE. Many cases are on record showing how complex and unexpected are the checks and relations between organic beings, which have to struggle together in the same country. I will give only a single instance, which, though a simple one, interested me. In Staffordshire, on the estate of a relation, where I had ample means of investigation, there was a large and extremely barren heath, which had never been touched by the hand of man; but several hundred acres of exactly the same nature had been enclosed twenty-five years previously and planted with Scotch fir. The change in the native vegetation of the planted part of the heath was most remarkable, more than is generally seen in passing from one quite different soil to another: not only the proportional numbers of the heath-plants were wholly changed, but twelve species of plants (not counting grasses and carices) flourished in the plantations, which could not be found on the heath. The effect on the insects must have been still greater, for six insectivorous birds were very common in the plantations, which were not to be seen on the heath; and the heath was frequented by two or three distinct insectivorous birds. Here we see how potent has been the effect of the introduction of a single tree, nothing whatever else having been done, with the exception of the land having been enclosed, so that cattle could not enter. But how important an element enclosure is, I plainly saw near Farnham, in Surrey. Here there are extensive heaths, with a few clumps of old Scotch firs on the distant hill-tops: within the last ten years large spaces have been enclosed, and self-sown firs are now springing up in multitudes, so close together that all cannot live. When I ascertained that these young trees had not been sown or planted I was so much surprised at their numbers that I went to several points of view, whence I could examine hundreds of acres of the unenclosed heath, and literally I could not see a single Scotch fir, except the old planted clumps. But on looking closely between the stems of the heath, I found a multitude of seedlings and little trees, which had been perpetually browsed down by the cattle. In one square yard, at a point some hundred yards distant from one of the old clumps, I counted thirty-two little trees; and one of them, with twenty-six rings of growth, had, during many years tried to raise its head above the stems of the heath, and had failed. No wonder that, as soon as the land was enclosed, it became thickly clothed with vigorously growing young firs. Yet the heath was so extremely barren and so extensive that no one would ever have imagined that cattle would have so closely and effectually searched it for food. Here we see that cattle absolutely determine the existence of the Scotch fir; but in several parts of the world insects determine the existence of cattle. Perhaps Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater number in Paraguay of a certain fly, which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by other parasitic insects. Hence, if certain insectivorous birds were to decrease in Paraguay, the parasitic insects would probably increase; and this would lessen the number of the navel-frequenting flies--then cattle and horses would become feral, and this would certainly greatly alter (as indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects; and this, as we have just seen in Staffordshire, the insectivorous birds, and so onwards in ever-increasing circles of complexity. Not that under nature the relations will ever be as simple as this. Battle within battle must be continually recurring with varying success; and yet in the long-run the forces are so nicely balanced that the face of nature remains for long periods of time uniform, though assuredly the merest trifle would give the victory to one organic being over another. Nevertheless, so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life! I am tempted to give one more instance showing how plants and animals, remote in the scale of nature, are bound together by a web of complex relations. I shall hereafter have occasion to show that the exotic Lobelia fulgens is never visited in my garden by insects, and consequently, from its peculiar structure, never sets a seed. Nearly all our orchidaceous plants absolutely require the visits of insects to remove their pollen-masses and thus to fertilise them. I find from experiments that humble-bees are almost indispensable to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower. I have also found that the visits of bees are necessary for the fertilisation of some kinds of clover; for instance twenty heads of Dutch clover (Trifolium repens) yielded 2,290 seeds, but twenty other heads, protected from bees, produced not one. Again, 100 heads of red clover (T. pratense) produced 2,700 seeds, but the same number of protected heads produced not a single seed. Humble bees alone visit red clover, as other bees cannot reach the nectar. It has been suggested that moths may fertilise the clovers; but I doubt whether they could do so in the case of the red clover, from their weight not being sufficient to depress the wing petals. Hence we may infer as highly probable that, if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great measure upon the number of field-mice, which destroy their combs and nests; and Colonel Newman, who has long attended to the habits of humble-bees, believes that "more than two-thirds of them are thus destroyed all over England." Now the number of mice is largely dependent, as every one knows, on the number of cats; and Colonel Newman says, "Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice." Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district! In the case of every species, many different checks, acting at different periods of life, and during different seasons or years, probably come into play; some one check or some few being generally the most potent, but all will concur in determining the average number, or even the existence of the species. In some cases it can be shown that widely-different checks act on the same species in different districts. When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this! Every one has heard that when an American forest is cut down, a very different vegetation springs up; but it has been observed that ancient Indian ruins in the Southern United States, which must formerly have been cleared of trees, now display the same beautiful diversity and proportion of kinds as in the surrounding virgin forests. What a struggle must have gone on during long centuries between the several kinds of trees, each annually scattering its seeds by the thousand; what war between insect and insect--between insects, snails, and other animals with birds and beasts of prey--all striving to increase, all feeding on each other, or on the trees, their seeds and seedlings, or on the other plants which first clothed the ground and thus checked the growth of the trees. Throw up a handful of feathers, and all fall to the ground according to definite laws; but how simple is the problem where each shall fall compared to that of the action and reaction of the innumerable plants and animals which have determined, in the course of centuries, the proportional numbers and kinds of trees now growing on the old Indian ruins! The dependency of one organic being on another, as of a parasite on its prey, lies generally between beings remote in the scale of nature. This is likewise sometimes the case with those which may strictly be said to struggle with each other for existence, as in the case of locusts and grass-feeding quadrupeds. But the struggle will almost invariably be most severe between the individuals of the same species, for they frequent the same districts, require the same food, and are exposed to the same dangers. In the case of varieties of the same species, the struggle will generally be almost equally severe, and we sometimes see the contest soon decided: for instance, if several varieties of wheat be sown together, and the mixed seed be resown, some of the varieties which best suit the soil or climate, or are naturally the most fertile, will beat the others and so yield more seed, and will consequently in a few years supplant the other varieties. To keep up a mixed stock of even such extremely close varieties as the variously coloured sweet-peas, they must be each year harvested separately, and the seed then mixed in due proportion, otherwise the weaker kinds will steadily decrease in number and disappear. So again with the varieties of sheep: it has been asserted that certain mountain-varieties will starve out other mountain-varieties, so that they cannot be kept together. The same result has followed from keeping together different varieties of the medicinal leech. It may even be doubted whether the varieties of any of our domestic plants or animals have so exactly the same strength, habits, and constitution, that the original proportions of a mixed stock (crossing being prevented) could be kept up for half-a-dozen generations, if they were allowed to struggle together, in the same manner as beings in a state of nature, and if the seed or young were not annually preserved in due proportion. STRUGGLE FOR LIFE MOST SEVERE BETWEEN INDIVIDUALS AND VARIETIES OF THE SAME SPECIES. As the species of the same genus usually have, though by no means invariably, much similarity in habits and constitution, and always in structure, the struggle will generally be more severe between them, if they come into competition with each other, than between the species of distinct genera. We see this in the recent extension over parts of the United States of one species of swallow having caused the decrease of another species. The recent increase of the missel-thrush in parts of Scotland has caused the decrease of the song-thrush. How frequently we hear of one species of rat taking the place of another species under the most different climates! In Russia the small Asiatic cockroach has everywhere driven before it its great congener. In Australia the imported hive-bee is rapidly exterminating the small, stingless native bee. One species of charlock has been known to supplant another species; and so in other cases. We can dimly see why the competition should be most severe between allied forms, which fill nearly the same place in the economy of nature; but probably in no one case could we precisely say why one species has been victorious over another in the great battle of life. A corollary of the highest importance may be deduced from the foregoing remarks, namely, that the structure of every organic being is related, in the most essential yet often hidden manner, to that of all other organic beings, with which it comes into competition for food or residence, or from which it has to escape, or on which it preys. This is obvious in the structure of the teeth and talons of the tiger; and in that of the legs and claws of the parasite which clings to the hair on the tiger's body. But in the beautifully plumed seed of the dandelion, and in the flattened and fringed legs of the water-beetle, the relation seems at first confined to the elements of air and water. Yet the advantage of the plumed seeds no doubt stands in the closest relation to the land being already thickly clothed with other plants; so that the seeds may be widely distributed and fall on unoccupied ground. In the water-beetle, the structure of its legs, so well adapted for diving, allows it to compete with other aquatic insects, to hunt for its own prey, and to escape serving as prey to other animals. The store of nutriment laid up within the seeds of many plants seems at first sight to have no sort of relation to other plants. But from the strong growth of young plants produced from such seeds, as peas and beans, when sown in the midst of long grass, it may be suspected that the chief use of the nutriment in the seed is to favour the growth of the seedlings, whilst struggling with other plants growing vigorously all around. Look at a plant in the midst of its range! Why does it not double or quadruple its numbers? We know that it can perfectly well withstand a little more heat or cold, dampness or dryness, for elsewhere it ranges into slightly hotter or colder, damper or drier districts. In this case we can clearly see that if we wish in imagination to give the plant the power of increasing in numbers, we should have to give it some advantage over its competitors, or over the animals which prey on it. On the confines of its geographical range, a change of constitution with respect to climate would clearly be an advantage to our plant; but we have reason to believe that only a few plants or animals range so far, that they are destroyed exclusively by the rigour of the climate. Not until we reach the extreme confines of life, in the Arctic regions or on the borders of an utter desert, will competition cease. The land may be extremely cold or dry, yet there will be competition between some few species, or between the individuals of the same species, for the warmest or dampest spots. Hence we can see that when a plant or animal is placed in a new country, among new competitors, the conditions of its life will generally be changed in an essential manner, although the climate may be exactly the same as in its former home. If its average numbers are to increase in its new home, we should have to modify it in a different way to what we should have had to do in its native country; for we should have to give it some advantage over a different set of competitors or enemies. It is good thus to try in imagination to give any one species an advantage over another. Probably in no single instance should we know what to do. This ought to convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary, as it is difficult to acquire. All that we can do is to keep steadily in mind that each organic being is striving to increase in a geometrical ratio; that each, at some period of its life, during some season of the year, during each generation, or at intervals, has to struggle for life and to suffer great destruction. When we reflect on this struggle we may console ourselves with the full belief that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply. CHAPTER IV. NATURAL SELECTION; OR THE SURVIVAL OF THE FITTEST. Natural Selection--its power compared with man's selection--its power on characters of trifling importance--its power at all ages and on both sexes--Sexual Selection--On the generality of intercrosses between individuals of the same species--Circumstances favourable and unfavourable to the results of Natural Selection, namely, intercrossing, isolation, number of individuals--Slow action--Extinction caused by Natural Selection--Divergence of Character, related to the diversity of inhabitants of any small area and to naturalisation--Action of Natural Selection, through Divergence of Character and Extinction, on the descendants from a common parent--Explains the Grouping of all organic beings--Advance in organisation--Low forms preserved--Convergence of character--Indefinite multiplication of species--Summary. How will the struggle for existence, briefly discussed in the last chapter, act in regard to variation? Can the principle of selection, which we have seen is so potent in the hands of man, apply under nature? I think we shall see that it can act most efficiently. Let the endless number of slight variations and individual differences occurring in our domestic productions, and, in a lesser degree, in those under nature, be borne in mind; as well as the strength of the hereditary tendency. Under domestication, it may truly be said that the whole organisation becomes in some degree plastic. But the variability, which we almost universally meet with in our domestic productions is not directly produced, as Hooker and Asa Gray have well remarked, by man; he can neither originate varieties nor prevent their occurrence; he can only preserve and accumulate such as do occur. Unintentionally he exposes organic beings to new and changing conditions of life, and variability ensues; but similar changes of conditions might and do occur under nature. Let it also be borne in mind how infinitely complex and close-fitting are the mutual relations of all organic beings to each other and to their physical conditions of life; and consequently what infinitely varied diversities of structure might be of use to each being under changing conditions of life. Can it then be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life, should occur in the course of many successive generations? If such do occur, can we doubt (remembering that many more individuals are born than can possibly survive) that individuals having any advantage, however slight, over others, would have the best chance of surviving and procreating their kind? On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed. This preservation of favourable individual differences and variations, and the destruction of those which are injurious, I have called Natural Selection, or the Survival of the Fittest. Variations neither useful nor injurious would not be affected by natural selection, and would be left either a fluctuating element, as perhaps we see in certain polymorphic species, or would ultimately become fixed, owing to the nature of the organism and the nature of the conditions. Several writers have misapprehended or objected to the term Natural Selection. Some have even imagined that natural selection induces variability, whereas it implies only the preservation of such variations as arise and are beneficial to the being under its conditions of life. No one objects to agriculturists speaking of the potent effects of man's selection; and in this case the individual differences given by nature, which man for some object selects, must of necessity first occur. Others have objected that the term selection implies conscious choice in the animals which become modified; and it has even been urged that, as plants have no volition, natural selection is not applicable to them! In the literal sense of the word, no doubt, natural selection is a false term; but who ever objected to chemists speaking of the elective affinities of the various elements?--and yet an acid cannot strictly be said to elect the base with which it in preference combines. It has been said that I speak of natural selection as an active power or Deity; but who objects to an author speaking of the attraction of gravity as ruling the movements of the planets? Every one knows what is meant and is implied by such metaphorical expressions; and they are almost necessary for brevity. So again it is difficult to avoid personifying the word Nature; but I mean by nature, only the aggregate action and product of many natural laws, and by laws the sequence of events as ascertained by us. With a little familiarity such superficial objections will be forgotten. We shall best understand the probable course of natural selection by taking the case of a country undergoing some slight physical change, for instance, of climate. The proportional numbers of its inhabitants will almost immediately undergo a change, and some species will probably become extinct. We may conclude, from what we have seen of the intimate and complex manner in which the inhabitants of each country are bound together, that any change in the numerical proportions of the inhabitants, independently of the change of climate itself, would seriously affect the others. If the country were open on its borders, new forms would certainly immigrate, and this would likewise seriously disturb the relations of some of the former inhabitants. Let it be remembered how powerful the influence of a single introduced tree or mammal has been shown to be. But in the case of an island, or of a country partly surrounded by barriers, into which new and better adapted forms could not freely enter, we should then have places in the economy of nature which would assuredly be better filled up if some of the original inhabitants were in some manner modified; for, had the area been open to immigration, these same places would have been seized on by intruders. In such cases, slight modifications, which in any way favoured the individuals of any species, by better adapting them to their altered conditions, would tend to be preserved; and natural selection would have free scope for the work of improvement. We have good reason to believe, as shown in the first chapter, that changes in the conditions of life give a tendency to increased variability; and in the foregoing cases the conditions the changed, and this would manifestly be favourable to natural selection, by affording a better chance of the occurrence of profitable variations. Unless such occur, natural selection can do nothing. Under the term of "variations," it must never be forgotten that mere individual differences are included. As man can produce a great result with his domestic animals and plants by adding up in any given direction individual differences, so could natural selection, but far more easily from having incomparably longer time for action. Nor do I believe that any great physical change, as of climate, or any unusual degree of isolation, to check immigration, is necessary in order that new and unoccupied places should be left for natural selection to fill up by improving some of the varying inhabitants. For as all the inhabitants of each country are struggling together with nicely balanced forces, extremely slight modifications in the structure or habits of one species would often give it an advantage over others; and still further modifications of the same kind would often still further increase the advantage, as long as the species continued under the same conditions of life and profited by similar means of subsistence and defence. No country can be named in which all the native inhabitants are now so perfectly adapted to each other and to the physical conditions under which they live, that none of them could be still better adapted or improved; for in all countries, the natives have been so far conquered by naturalised productions that they have allowed some foreigners to take firm possession of the land. And as foreigners have thus in every country beaten some of the natives, we may safely conclude that the natives might have been modified with advantage, so as to have better resisted the intruders. As man can produce, and certainly has produced, a great result by his methodical and unconscious means of selection, what may not natural selection effect? Man can act only on external and visible characters: Nature, if I may be allowed to personify the natural preservation or survival of the fittest, cares nothing for appearances, except in so far as they are useful to any being. She can act on every internal organ, on every shade of constitutional difference, on the whole machinery of life. Man selects only for his own good; Nature only for that of the being which she tends. Every selected character is fully exercised by her, as is implied by the fact of their selection. Man keeps the natives of many climates in the same country. He seldom exercises each selected character in some peculiar and fitting manner; he feeds a long and a short-beaked pigeon on the same food; he does not exercise a long-backed or long-legged quadruped in any peculiar manner; he exposes sheep with long and short wool to the same climate; does not allow the most vigorous males to struggle for the females; he does not rigidly destroy all inferior animals, but protects during each varying season, as far as lies in his power, all his productions. He often begins his selection by some half-monstrous form, or at least by some modification prominent enough to catch the eye or to be plainly useful to him. Under nature, the slightest differences of structure or constitution may well turn the nicely-balanced scale in the struggle for life, and so be preserved. How fleeting are the wishes and efforts of man! How short his time, and consequently how poor will be his results, compared with those accumulated by Nature during whole geological periods! Can we wonder, then, that Nature's productions should be far "truer" in character than man's productions; that they should be infinitely better adapted to the most complex conditions of life, and should plainly bear the stamp of far higher workmanship? It may metaphorically be said that natural selection is daily and hourly scrutinising, throughout the world, the slightest variations; rejecting those that are bad, preserving and adding up all that are good; silently and insensibly working, WHENEVER AND WHEREVER OPPORTUNITY OFFERS, at the improvement of each organic being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages, and then so imperfect is our view into long-past geological ages that we see only that the forms of life are now different from what they formerly were. In order that any great amount of modification should be effected in a species, a variety, when once formed must again, perhaps after a long interval of time, vary or present individual differences of the same favourable nature as before; and these must again be preserved, and so onward, step by step. Seeing that individual differences of the same kind perpetually recur, this can hardly be considered as an unwarrantable assumption. But whether it is true, we can judge only by seeing how far the hypothesis accords with and explains the general phenomena of nature. On the other hand, the ordinary belief that the amount of possible variation is a strictly limited quantity, is likewise a simple assumption. Although natural selection can act only through and for the good of each being, yet characters and structures, which we are apt to consider as of very trifling importance, may thus be acted on. When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey; and hawks are guided by eyesight to their prey,--so much so that on parts of the continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence natural selection might be effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. Nor ought we to think that the occasional destruction of an animal of any particular colour would produce little effect; we should remember how essential it is in a flock of white sheep to destroy a lamb with the faintest trace of black. We have seen how the colour of hogs, which feed on the "paint-root" in Virginia, determines whether they shall live or die. In plants, the down on the fruit and the colour of the flesh are considered by botanists as characters of the most trifling importance; yet we hear from an excellent horticulturist, Downing, that in the United States smooth-skinned fruits suffer far more from a beetle, a Curculio, than those with down; that purple plums suffer far more from a certain disease than yellow plums; whereas another disease attacks yellow-fleshed peaches far more than those with other coloured flesh. If, with all the aids of art, these slight differences make a great difference in cultivating the several varieties, assuredly, in a state of nature, where the trees would have to struggle with other trees and with a host of enemies, such differences would effectually settle which variety, whether a smooth or downy, a yellow or a purple-fleshed fruit, should succeed. In looking at many small points of difference between species, which, as far as our ignorance permits us to judge, seem quite unimportant, we must not forget that climate, food, etc., have no doubt produced some direct effect. It is also necessary to bear in mind that, owing to the law of correlation, when one part varies and the variations are accumulated through natural selection, other modifications, often of the most unexpected nature, will ensue. As we see that those variations which, under domestication, appear at any particular period of life, tend to reappear in the offspring at the same period; for instance, in the shape, size and flavour of the seeds of the many varieties of our culinary and agricultural plants; in the caterpillar and cocoon stages of the varieties of the silkworm; in the eggs of poultry, and in the colour of the down of their chickens; in the horns of our sheep and cattle when nearly adult; so in a state of nature natural selection will be enabled to act on and modify organic beings at any age, by the accumulation of variations profitable at that age, and by their inheritance at a corresponding age. If it profit a plant to have its seeds more and more widely disseminated by the wind, I can see no greater difficulty in this being effected through natural selection, than in the cotton-planter increasing and improving by selection the down in the pods on his cotton-trees. Natural selection may modify and adapt the larva of an insect to a score of contingencies, wholly different from those which concern the mature insect; and these modifications may affect, through correlation, the structure of the adult. So, conversely, modifications in the adult may affect the structure of the larva; but in all cases natural selection will ensure that they shall not be injurious: for if they were so, the species would become extinct. Natural selection will modify the structure of the young in relation to the parent and of the parent in relation to the young. In social animals it will adapt the structure of each individual for the benefit of the whole community; if the community profits by the selected change. What natural selection cannot do, is to modify the structure of one species, without giving it any advantage, for the good of another species; and though statements to this effect may be found in works of natural history, I cannot find one case which will bear investigation. A structure used only once in an animal's life, if of high importance to it, might be modified to any extent by natural selection; for instance, the great jaws possessed by certain insects, used exclusively for opening the cocoon--or the hard tip to the beak of unhatched birds, used for breaking the eggs. It has been asserted, that of the best short-beaked tumbler-pigeons a greater number perish in the egg than are able to get out of it; so that fanciers assist in the act of hatching. Now, if nature had to make the beak of a full-grown pigeon very short for the bird's own advantage, the process of modification would be very slow, and there would be simultaneously the most rigorous selection of all the young birds within the egg, which had the most powerful and hardest beaks, for all with weak beaks would inevitably perish: or, more delicate and more easily broken shells might be selected, the thickness of the shell being known to vary like every other structure. It may be well here to remark that with all beings there must be much fortuitous destruction, which can have little or no influence on the course of natural selection. For instance, a vast number of eggs or seeds are annually devoured, and these could be modified through natural selection only if they varied in some manner which protected them from their enemies. Yet many of these eggs or seeds would perhaps, if not destroyed, have yielded individuals better adapted to their conditions of life than any of those which happened to survive. So again a vast number of mature animals and plants, whether or not they be the best adapted to their conditions, must be annually destroyed by accidental causes, which would not be in the least degree mitigated by certain changes of structure or constitution which would in other ways be beneficial to the species. But let the destruction of the adults be ever so heavy, if the number which can exist in any district be not wholly kept down by such causes--or again let the destruction of eggs or seeds be so great that only a hundredth or a thousandth part are developed--yet of those which do survive, the best adapted individuals, supposing that there is any variability in a favourable direction, will tend to propagate their kind in larger numbers than the less well adapted. If the numbers be wholly kept down by the causes just indicated, as will often have been the case, natural selection will be powerless in certain beneficial directions; but this is no valid objection to its efficiency at other times and in other ways; for we are far from having any reason to suppose that many species ever undergo modification and improvement at the same time in the same area. SEXUAL SELECTION. Inasmuch as peculiarities often appear under domestication in one sex and become hereditarily attached to that sex, so no doubt it will be under nature. Thus it is rendered possible for the two sexes to be modified through natural selection in relation to different habits of life, as is sometimes the case; or for one sex to be modified in relation to the other sex, as commonly occurs. This leads me to say a few words on what I have called sexual selection. This form of selection depends, not on a struggle for existence in relation to other organic beings or to external conditions, but on a struggle between the individuals of one sex, generally the males, for the possession of the other sex. The result is not death to the unsuccessful competitor, but few or no offspring. Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases victory depends not so much on general vigour, but on having special weapons, confined to the male sex. A hornless stag or spurless cock would have a poor chance of leaving numerous offspring. Sexual selection, by always allowing the victor to breed, might surely give indomitable courage, length of spur, and strength to the wing to strike in the spurred leg, in nearly the same manner as does the brutal cockfighter by the careful selection of his best cocks. How low in the scale of nature the law of battle descends I know not; male alligators have been described as fighting, bellowing, and whirling round, like Indians in a war-dance, for the possession of the females; male salmons have been observed fighting all day long; male stag-beetles sometimes bear wounds from the huge mandibles of other males; the males of certain hymenopterous insects have been frequently seen by that inimitable observer M. Fabre, fighting for a particular female who sits by, an apparently unconcerned beholder of the struggle, and then retires with the conqueror. The war is, perhaps, severest between the males of polygamous animals, and these seem oftenest provided with special weapons. The males of carnivorous animals are already well armed; though to them and to others, special means of defence may be given through means of sexual selection, as the mane of the lion, and the hooked jaw to the male salmon; for the shield may be as important for victory as the sword or spear. Among birds, the contest is often of a more peaceful character. All those who have attended to the subject, believe that there is the severest rivalry between the males of many species to attract, by singing, the females. The rock-thrush of Guiana, birds of paradise, and some others, congregate, and successive males display with the most elaborate care, and show off in the best manner, their gorgeous plumage; they likewise perform strange antics before the females, which, standing by as spectators, at last choose the most attractive partner. Those who have closely attended to birds in confinement well know that they often take individual preferences and dislikes: thus Sir R. Heron has described how a pied peacock was eminently attractive to all his hen birds. I cannot here enter on the necessary details; but if man can in a short time give beauty and an elegant carriage to his bantams, according to his standard of beauty, I can see no good reason to doubt that female birds, by selecting, during thousands of generations, the most melodious or beautiful males, according to their standard of beauty, might produce a marked effect. Some well-known laws, with respect to the plumage of male and female birds, in comparison with the plumage of the young, can partly be explained through the action of sexual selection on variations occurring at different ages, and transmitted to the males alone or to both sexes at corresponding ages; but I have not space here to enter on this subject. Thus it is, as I believe, that when the males and females of any animal have the same general habits of life, but differ in structure, colour, or ornament, such differences have been mainly caused by sexual selection: that is, by individual males having had, in successive generations, some slight advantage over other males, in their weapons, means of defence, or charms; which they have transmitted to their male offspring alone. Yet, I would not wish to attribute all sexual differences to this agency: for we see in our domestic animals peculiarities arising and becoming attached to the male sex, which apparently have not been augmented through selection by man. The tuft of hair on the breast of the wild turkey-cock cannot be of any use, and it is doubtful whether it can be ornamental in the eyes of the female bird; indeed, had the tuft appeared under domestication it would have been called a monstrosity. ILLUSTRATIONS OF THE ACTION OF NATURAL SELECTION, OR THE SURVIVAL OF THE FITTEST. In order to make it clear how, as I believe, natural selection acts, I must beg permission to give one or two imaginary illustrations. Let us take the case of a wolf, which preys on various animals, securing some by craft, some by strength, and some by fleetness; and let us suppose that the fleetest prey, a deer for instance, had from any change in the country increased in numbers, or that other prey had decreased in numbers, during that season of the year when the wolf was hardest pressed for food. Under such circumstances the swiftest and slimmest wolves have the best chance of surviving, and so be preserved or selected, provided always that they retained strength to master their prey at this or some other period of the year, when they were compelled to prey on other animals. I can see no more reason to doubt that this would be the result, than that man should be able to improve the fleetness of his greyhounds by careful and methodical selection, or by that kind of unconscious selection which follows from each man trying to keep the best dogs without any thought of modifying the breed. I may add that, according to Mr. Pierce, there are two varieties of the wolf inhabiting the Catskill Mountains, in the United States, one with a light greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which more frequently attacks the shepherd's flocks. Even without any change in the proportional numbers of the animals on which our wolf preyed, a cub might be born with an innate tendency to pursue certain kinds of prey. Nor can this be thought very improbable; for we often observe great differences in the natural tendencies of our domestic animals; one cat, for instance, taking to catch rats, another mice; one cat, according to Mr. St. John, bringing home winged game, another hares or rabbits, and another hunting on marshy ground and almost nightly catching woodcocks or snipes. The tendency to catch rats rather than mice is known to be inherited. Now, if any slight innate change of habit or of structure benefited an individual wolf, it would have the best chance of surviving and of leaving offspring. Some of its young would probably inherit the same habits or structure, and by the repetition of this process, a new variety might be formed which would either supplant or coexist with the parent-form of wolf. Or, again, the wolves inhabiting a mountainous district, and those frequenting the lowlands, would naturally be forced to hunt different prey; and from the continued preservation of the individuals best fitted for the two sites, two varieties might slowly be formed. These varieties would cross and blend where they met; but to this subject of intercrossing we shall soon have to return. I may add, that, according to Mr. Pierce, there are two varieties of the wolf inhabiting the Catskill Mountains in the United States, one with a light greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which more frequently attacks the shepherd's flocks. It should be observed that in the above illustration, I speak of the slimmest individual wolves, and not of any single strongly marked variation having been preserved. In former editions of this work I sometimes spoke as if this latter alternative had frequently occurred. I saw the great importance of individual differences, and this led me fully to discuss the results of unconscious selection by man, which depends on the preservation of all the more or less valuable individuals, and on the destruction of the worst. I saw, also, that the preservation in a state of nature of any occasional deviation of structure, such as a monstrosity, would be a rare event; and that, if at first preserved, it would generally be lost by subsequent intercrossing with ordinary individuals. Nevertheless, until reading an able and valuable article in the "North British Review" (1867), I did not appreciate how rarely single variations, whether slight or strongly marked, could be perpetuated. The author takes the case of a pair of animals, producing during their lifetime two hundred offspring, of which, from various causes of destruction, only two on an average survive to pro-create their kind. This is rather an extreme estimate for most of the higher animals, but by no means so for many of the lower organisms. He then shows that if a single individual were born, which varied in some manner, giving it twice as good a chance of life as that of the other individuals, yet the chances would be strongly against its survival. Supposing it to survive and to breed, and that half its young inherited the favourable variation; still, as the Reviewer goes onto show, the young would have only a slightly better chance of surviving and breeding; and this chance would go on decreasing in the succeeding generations. The justice of these remarks cannot, I think, be disputed. If, for instance, a bird of some kind could procure its food more easily by having its beak curved, and if one were born with its beak strongly curved, and which consequently flourished, nevertheless there would be a very poor chance of this one individual perpetuating its kind to the exclusion of the common form; but there can hardly be a doubt, judging by what we see taking place under domestication, that this result would follow from the preservation during many generations of a large number of individuals with more or less strongly curved beaks, and from the destruction of a still larger number with the straightest beaks. It should not, however, be overlooked that certain rather strongly marked variations, which no one would rank as mere individual differences, frequently recur owing to a similar organisation being similarly acted on--of which fact numerous instances could be given with our domestic productions. In such cases, if the varying individual did not actually transmit to its offspring its newly-acquired character, it would undoubtedly transmit to them, as long as the existing conditions remained the same, a still stronger tendency to vary in the same manner. There can also be little doubt that the tendency to vary in the same manner has often been so strong that all the individuals of the same species have been similarly modified without the aid of any form of selection. Or only a third, fifth, or tenth part of the individuals may have been thus affected, of which fact several instances could be given. Thus Graba estimates that about one-fifth of the guillemots in the Faroe Islands consist of a variety so well marked, that it was formerly ranked as a distinct species under the name of Uria lacrymans. In cases of this kind, if the variation were of a beneficial nature, the original form would soon be supplanted by the modified form, through the survival of the fittest. To the effects of intercrossing in eliminating variations of all kinds, I shall have to recur; but it may be here remarked that most animals and plants keep to their proper homes, and do not needlessly wander about; we see this even with migratory birds, which almost always return to the same spot. Consequently each newly-formed variety would generally be at first local, as seems to be the common rule with varieties in a state of nature; so that similarly modified individuals would soon exist in a small body together, and would often breed together. If the new variety were successful in its battle for life, it would slowly spread from a central district, competing with and conquering the unchanged individuals on the margins of an ever-increasing circle. It may be worth while to give another and more complex illustration of the action of natural selection. Certain plants excrete sweet juice, apparently for the sake of eliminating something injurious from the sap: this is effected, for instance, by glands at the base of the stipules in some Leguminosae, and at the backs of the leaves of the common laurel. This juice, though small in quantity, is greedily sought by insects; but their visits do not in any way benefit the plant. Now, let us suppose that the juice or nectar was excreted from the inside of the flowers of a certain number of plants of any species. Insects in seeking the nectar would get dusted with pollen, and would often transport it from one flower to another. The flowers of two distinct individuals of the same species would thus get crossed; and the act of crossing, as can be fully proved, gives rise to vigorous seedlings, which consequently would have the best chance of flourishing and surviving. The plants which produced flowers with the largest glands or nectaries, excreting most nectar, would oftenest be visited by insects, and would oftenest be crossed; and so in the long-run would gain the upper hand and form a local variety. The flowers, also, which had their stamens and pistils placed, in relation to the size and habits of the particular insect which visited them, so as to favour in any degree the transportal of the pollen, would likewise be favoured. We might have taken the case of insects visiting flowers for the sake of collecting pollen instead of nectar; and as pollen is formed for the sole purpose of fertilisation, its destruction appears to be a simple loss to the plant; yet if a little pollen were carried, at first occasionally and then habitually, by the pollen-devouring insects from flower to flower, and a cross thus effected, although nine-tenths of the pollen were destroyed it might still be a great gain to the plant to be thus robbed; and the individuals which produced more and more pollen, and had larger anthers, would be selected. When our plant, by the above process long continued, had been rendered highly attractive to insects, they would, unintentionally on their part, regularly carry pollen from flower to flower; and that they do this effectually I could easily show by many striking facts. I will give only one, as likewise illustrating one step in the separation of the sexes of plants. Some holly-trees bear only male flowers, which have four stamens producing a rather small quantity of pollen, and a rudimentary pistil; other holly-trees bear only female flowers; these have a full-sized pistil, and four stamens with shrivelled anthers, in which not a grain of pollen can be detected. Having found a female tree exactly sixty yards from a male tree, I put the stigmas of twenty flowers, taken from different branches, under the microscope, and on all, without exception, there were a few pollen-grains, and on some a profusion. As the wind had set for several days from the female to the male tree, the pollen could not thus have been carried. The weather had been cold and boisterous and therefore not favourable to bees, nevertheless every female flower which I examined had been effectually fertilised by the bees, which had flown from tree to tree in search of nectar. But to return to our imaginary case; as soon as the plant had been rendered so highly attractive to insects that pollen was regularly carried from flower to flower, another process might commence. No naturalist doubts the advantage of what has been called the "physiological division of labour;" hence we may believe that it would be advantageous to a plant to produce stamens alone in one flower or on one whole plant, and pistils alone in another flower or on another plant. In plants under culture and placed under new conditions of life, sometimes the male organs and sometimes the female organs become more or less impotent; now if we suppose this to occur in ever so slight a degree under nature, then, as pollen is already carried regularly from flower to flower, and as a more complete separation of the sexes of our plant would be advantageous on the principle of the division of labour, individuals with this tendency more and more increased, would be continually favoured or selected, until at last a complete separation of the sexes might be effected. It would take up too much space to show the various steps, through dimorphism and other means, by which the separation of the sexes in plants of various kinds is apparently now in progress; but I may add that some of the species of holly in North America are, according to Asa Gray, in an exactly intermediate condition, or, as he expresses it, are more or less dioeciously polygamous. Let us now turn to the nectar-feeding insects; we may suppose the plant of which we have been slowly increasing the nectar by continued selection, to be a common plant; and that certain insects depended in main part on its nectar for food. I could give many facts showing how anxious bees are to save time: for instance, their habit of cutting holes and sucking the nectar at the bases of certain flowers, which with a very little more trouble they can enter by the mouth. Bearing such facts in mind, it may be believed that under certain circumstances individual differences in the curvature or length of the proboscis, etc., too slight to be appreciated by us, might profit a bee or other insect, so that certain individuals would be able to obtain their food more quickly than others; and thus the communities to which they belonged would flourish and throw off many swarms inheriting the same peculiarities. The tubes of the corolla of the common red or incarnate clovers (Trifolium pratense and incarnatum) do not on a hasty glance appear to differ in length; yet the hive-bee can easily suck the nectar out of the incarnate clover, but not out of the common red clover, which is visited by humble-bees alone; so that whole fields of the red clover offer in vain an abundant supply of precious nectar to the hive-bee. That this nectar is much liked by the hive-bee is certain; for I have repeatedly seen, but only in the autumn, many hive-bees sucking the flowers through holes bitten in the base of the tube by humble bees. The difference in the length of the corolla in the two kinds of clover, which determines the visits of the hive-bee, must be very trifling; for I have been assured that when red clover has been mown, the flowers of the second crop are somewhat smaller, and that these are visited by many hive-bees. I do not know whether this statement is accurate; nor whether another published statement can be trusted, namely, that the Ligurian bee, which is generally considered a mere variety of the common hive-bee, and which freely crosses with it, is able to reach and suck the nectar of the red clover. Thus, in a country where this kind of clover abounded, it might be a great advantage to the hive-bee to have a slightly longer or differently constructed proboscis. On the other hand, as the fertility of this clover absolutely depends on bees visiting the flowers, if humble-bees were to become rare in any country, it might be a great advantage to the plant to have a shorter or more deeply divided corolla, so that the hive-bees should be enabled to suck its flowers. Thus I can understand how a flower and a bee might slowly become, either simultaneously or one after the other, modified and adapted to each other in the most perfect manner, by the continued preservation of all the individuals which presented slight deviations of structure mutually favourable to each other. I am well aware that this doctrine of natural selection, exemplified in the above imaginary instances, is open to the same objections which were first urged against Sir Charles Lyell's noble views on "the modern changes of the earth, as illustrative of geology;" but we now seldom hear the agencies which we see still at work, spoken of as trifling and insignificant, when used in explaining the excavation of the deepest valleys or the formation of long lines of inland cliffs. Natural selection acts only by the preservation and accumulation of small inherited modifications, each profitable to the preserved being; and as modern geology has almost banished such views as the excavation of a great valley by a single diluvial wave, so will natural selection banish the belief of the continued creation of new organic beings, or of any great and sudden modification in their structure. ON THE INTERCROSSING OF INDIVIDUALS. I must here introduce a short digression. In the case of animals and plants with separated sexes, it is of course obvious that two individuals must always (with the exception of the curious and not well understood cases of parthenogenesis) unite for each birth; but in the case of hermaphrodites this is far from obvious. Nevertheless there is reason to believe that with all hermaphrodites two individuals, either occasionally or habitually, concur for the reproduction of their kind. This view was long ago doubtfully suggested by Sprengel, Knight and Kolreuter. We shall presently see its importance; but I must here treat the subject with extreme brevity, though I have the materials prepared for an ample discussion. All vertebrate animals, all insects and some other large groups of animals, pair for each birth. Modern research has much diminished the number of supposed hermaphrodites and of real hermaphrodites a large number pair; that is, two individuals regularly unite for reproduction, which is all that concerns us. But still there are many hermaphrodite animals which certainly do not habitually pair, and a vast majority of plants are hermaphrodites. What reason, it may be asked, is there for supposing in these cases that two individuals ever concur in reproduction? As it is impossible here to enter on details, I must trust to some general considerations alone. In the first place, I have collected so large a body of facts, and made so many experiments, showing, in accordance with the almost universal belief of breeders, that with animals and plants a cross between different varieties, or between individuals of the same variety but of another strain, gives vigour and fertility to the offspring; and on the other hand, that CLOSE interbreeding diminishes vigour and fertility; that these facts alone incline me to believe that it is a general law of nature that no organic being fertilises itself for a perpetuity of generations; but that a cross with another individual is occasionally--perhaps at long intervals of time--indispensable. On the belief that this is a law of nature, we can, I think, understand several large classes of facts, such as the following, which on any other view are inexplicable. Every hybridizer knows how unfavourable exposure to wet is to the fertilisation of a flower, yet what a multitude of flowers have their anthers and stigmas fully exposed to the weather! If an occasional cross be indispensable, notwithstanding that the plant's own anthers and pistil stand so near each other as almost to ensure self-fertilisation, the fullest freedom for the entrance of pollen from another individual will explain the above state of exposure of the organs. Many flowers, on the other hand, have their organs of fructification closely enclosed, as in the great papilionaceous or pea-family; but these almost invariably present beautiful and curious adaptations in relation to the visits of insects. So necessary are the visits of bees to many papilionaceous flowers, that their fertility is greatly diminished if these visits be prevented. Now, it is scarcely possible for insects to fly from flower to flower, and not to carry pollen from one to the other, to the great good of the plant. Insects act like a camel-hair pencil, and it is sufficient, to ensure fertilisation, just to touch with the same brush the anthers of one flower and then the stigma of another; but it must not be supposed that bees would thus produce a multitude of hybrids between distinct species; for if a plant's own pollen and that from another species are placed on the same stigma, the former is so prepotent that it invariably and completely destroys, as has been shown by Gartner, the influence of the foreign pollen. When the stamens of a flower suddenly spring towards the pistil, or slowly move one after the other towards it, the contrivance seems adapted solely to ensure self-fertilisation; and no doubt it is useful for this end: but the agency of insects is often required to cause the stamens to spring forward, as Kolreuter has shown to be the case with the barberry; and in this very genus, which seems to have a special contrivance for self-fertilisation, it is well known that, if closely-allied forms or varieties are planted near each other, it is hardly possible to raise pure seedlings, so largely do they naturally cross. In numerous other cases, far from self-fertilisation being favoured, there are special contrivances which effectually prevent the stigma receiving pollen from its own flower, as I could show from the works of Sprengel and others, as well as from my own observations: for instance, in Lobelia fulgens, there is a really beautiful and elaborate contrivance by which all the infinitely numerous pollen-granules are swept out of the conjoined anthers of each flower, before the stigma of that individual flower is ready to receive them; and as this flower is never visited, at least in my garden, by insects, it never sets a seed, though by placing pollen from one flower on the stigma of another, I raise plenty of seedlings. Another species of Lobelia, which is visited by bees, seeds freely in my garden. In very many other cases, though there is no special mechanical contrivance to prevent the stigma receiving pollen from the same flower, yet, as Sprengel, and more recently Hildebrand and others have shown, and as I can confirm, either the anthers burst before the stigma is ready for fertilisation, or the stigma is ready before the pollen of that flower is ready, so that these so-named dichogamous plants have in fact separated sexes, and must habitually be crossed. So it is with the reciprocally dimorphic and trimorphic plants previously alluded to. How strange are these facts! How strange that the pollen and stigmatic surface of the same flower, though placed so close together, as if for the very purpose of self-fertilisation, should be in so many cases mutually useless to each other! How simply are these facts explained on the view of an occasional cross with a distinct individual being advantageous or indispensable! If several varieties of the cabbage, radish, onion, and of some other plants, be allowed to seed near each other, a large majority of the seedlings thus raised turn out, as I found, mongrels: for instance, I raised 233 seedling cabbages from some plants of different varieties growing near each other, and of these only 78 were true to their kind, and some even of these were not perfectly true. Yet the pistil of each cabbage-flower is surrounded not only by its own six stamens but by those of the many other flowers on the same plant; and the pollen of each flower readily gets on its stigma without insect agency; for I have found that plants carefully protected from insects produce the full number of pods. How, then, comes it that such a vast number of the seedlings are mongrelized? It must arise from the pollen of a distinct VARIETY having a prepotent effect over the flower's own pollen; and that this is part of the general law of good being derived from the intercrossing of distinct individuals of the same species. When distinct SPECIES are crossed the case is reversed, for a plant's own pollen is always prepotent over foreign pollen; but to this subject we shall return in a future chapter. In the case of a large tree covered with innumerable flowers, it may be objected that pollen could seldom be carried from tree to tree, and at most only from flower to flower on the same tree; and flowers on the same tree can be considered as distinct individuals only in a limited sense. I believe this objection to be valid, but that nature has largely provided against it by giving to trees a strong tendency to bear flowers with separated sexes. When the sexes are separated, although the male and female flowers may be produced on the same tree, pollen must be regularly carried from flower to flower; and this will give a better chance of pollen being occasionally carried from tree to tree. That trees belonging to all orders have their sexes more often separated than other plants, I find to be the case in this country; and at my request Dr. Hooker tabulated the trees of New Zealand, and Dr. Asa Gray those of the United States, and the result was as I anticipated. On the other hand, Dr. Hooker informs me that the rule does not hold good in Australia: but if most of the Australian trees are dichogamous, the same result would follow as if they bore flowers with separated sexes. I have made these few remarks on trees simply to call attention to the subject. Turning for a brief space to animals: various terrestrial species are hermaphrodites, such as the land-mollusca and earth-worms; but these all pair. As yet I have not found a single terrestrial animal which can fertilise itself. This remarkable fact, which offers so strong a contrast with terrestrial plants, is intelligible on the view of an occasional cross being indispensable; for owing to the nature of the fertilising element there are no means, analogous to the action of insects and of the wind with plants, by which an occasional cross could be effected with terrestrial animals without the concurrence of two individuals. Of aquatic animals, there are many self-fertilising hermaphrodites; but here the currents of water offer an obvious means for an occasional cross. As in the case of flowers, I have as yet failed, after consultation with one of the highest authorities, namely, Professor Huxley, to discover a single hermaphrodite animal with the organs of reproduction so perfectly enclosed that access from without, and the occasional influence of a distinct individual, can be shown to be physically impossible. Cirripedes long appeared to me to present, under this point of view, a case of great difficulty; but I have been enabled, by a fortunate chance, to prove that two individuals, though both are self-fertilising hermaphrodites, do sometimes cross. It must have struck most naturalists as a strange anomaly that, both with animals and plants, some species of the same family and even of the same genus, though agreeing closely with each other in their whole organisation, are hermaphrodites, and some unisexual. But if, in fact, all hermaphrodites do occasionally intercross, the difference between them and unisexual species is, as far as function is concerned, very small. From these several considerations and from the many special facts which I have collected, but which I am unable here to give, it appears that with animals and plants an occasional intercross between distinct individuals is a very general, if not universal, law of nature. CIRCUMSTANCES FAVOURABLE FOR THE PRODUCTION OF NEW FORMS THROUGH NATURAL SELECTION. This is an extremely intricate subject. A great amount of variability, under which term individual differences are always included, will evidently be favourable. A large number of individuals, by giving a better chance within any given period for the appearance of profitable variations, will compensate for a lesser amount of variability in each individual, and is, I believe, a highly important element of success. Though nature grants long periods of time for the work of natural selection, she does not grant an indefinite period; for as all organic beings are striving to seize on each place in the economy of nature, if any one species does not become modified and improved in a corresponding degree with its competitors it will be exterminated. Unless favourable variations be inherited by some at least of the offspring, nothing can be effected by natural selection. The tendency to reversion may often check or prevent the work; but as this tendency has not prevented man from forming by selection numerous domestic races, why should it prevail against natural selection? In the case of methodical selection, a breeder selects for some definite object, and if the individuals be allowed freely to intercross, his work will completely fail. But when many men, without intending to alter the breed, have a nearly common standard of perfection, and all try to procure and breed from the best animals, improvement surely but slowly follows from this unconscious process of selection, notwithstanding that there is no separation of selected individuals. Thus it will be under nature; for within a confined area, with some place in the natural polity not perfectly occupied, all the individuals varying in the right direction, though in different degrees, will tend to be preserved. But if the area be large, its several districts will almost certainly present different conditions of life; and then, if the same species undergoes modification in different districts, the newly formed varieties will intercross on the confines of each. But we shall see in the sixth chapter that intermediate varieties, inhabiting intermediate districts, will in the long run generally be supplanted by one of the adjoining varieties. Intercrossing will chiefly affect those animals which unite for each birth and wander much, and which do not breed at a very quick rate. Hence with animals of this nature, for instance birds, varieties will generally be confined to separated countries; and this I find to be the case. With hermaphrodite organisms which cross only occasionally, and likewise with animals which unite for each birth, but which wander little and can increase at a rapid rate, a new and improved variety might be quickly formed on any one spot, and might there maintain itself in a body and afterward spread, so that the individuals of the new variety would chiefly cross together. On this principle nurserymen always prefer saving seed from a large body of plants, as the chance of intercrossing is thus lessened. Even with animals which unite for each birth, and which do not propagate rapidly, we must not assume that free intercrossing would always eliminate the effects of natural selection; for I can bring forward a considerable body of facts showing that within the same area two varieties of the same animal may long remain distinct, from haunting different stations, from breeding at slightly different seasons, or from the individuals of each variety preferring to pair together. Intercrossing plays a very important part in nature by keeping the individuals of the same species, or of the same variety, true and uniform in character. It will obviously thus act far more efficiently with those animals which unite for each birth; but, as already stated, we have reason to believe that occasional intercrosses take place with all animals and plants. Even if these take place only at long intervals of time, the young thus produced will gain so much in vigour and fertility over the offspring from long-continued self-fertilisation, that they will have a better chance of surviving and propagating their kind; and thus in the long run the influence of crosses, even at rare intervals, will be great. With respect to organic beings extremely low in the scale, which do not propagate sexually, nor conjugate, and which cannot possibly intercross, uniformity of character can be retained by them under the same conditions of life, only through the principle of inheritance, and through natural selection which will destroy any individuals departing from the proper type. If the conditions of life change and the form undergoes modification, uniformity of character can be given to the modified offspring, solely by natural selection preserving similar favourable variations. Isolation also is an important element in the modification of species through natural selection. In a confined or isolated area, if not very large, the organic and inorganic conditions of life will generally be almost uniform; so that natural selection will tend to modify all the varying individuals of the same species in the same manner. Intercrossing with the inhabitants of the surrounding districts, will also be thus prevented. Moritz Wagner has lately published an interesting essay on this subject, and has shown that the service rendered by isolation in preventing crosses between newly-formed varieties is probably greater even than I supposed. But from reasons already assigned I can by no means agree with this naturalist, that migration and isolation are necessary elements for the formation of new species. The importance of isolation is likewise great in preventing, after any physical change in the conditions, such as of climate, elevation of the land, etc., the immigration of better adapted organisms; and thus new places in the natural economy of the district will be left open to be filled up by the modification of the old inhabitants. Lastly, isolation will give time for a new variety to be improved at a slow rate; and this may sometimes be of much importance. If, however, an isolated area be very small, either from being surrounded by barriers, or from having very peculiar physical conditions, the total number of the inhabitants will be small; and this will retard the production of new species through natural selection, by decreasing the chances of favourable variations arising. The mere lapse of time by itself does nothing, either for or against natural selection. I state this because it has been erroneously asserted that the element of time has been assumed by me to play an all-important part in modifying species, as if all the forms of life were necessarily undergoing change through some innate law. Lapse of time is only so far important, and its importance in this respect is great, that it gives a better chance of beneficial variations arising and of their being selected, accumulated, and fixed. It likewise tends to increase the direct action of the physical conditions of life, in relation to the constitution of each organism. If we turn to nature to test the truth of these remarks, and look at any small isolated area, such as an oceanic island, although the number of the species inhabiting it is small, as we shall see in our chapter on Geographical Distribution; yet of these species a very large proportion are endemic,--that is, have been produced there and nowhere else in the world. Hence an oceanic island at first sight seems to have been highly favourable for the production of new species. But we may thus deceive ourselves, for to ascertain whether a small isolated area, or a large open area like a continent, has been most favourable for the production of new organic forms, we ought to make the comparison within equal times; and this we are incapable of doing. Although isolation is of great importance in the production of new species, on the whole I am inclined to believe that largeness of area is still more important, especially for the production of species which shall prove capable of enduring for a long period, and of spreading widely. Throughout a great and open area, not only will there be a better chance of favourable variations, arising from the large number of individuals of the same species there supported, but the conditions of life are much more complex from the large number of already existing species; and if some of these many species become modified and improved, others will have to be improved in a corresponding degree, or they will be exterminated. Each new form, also, as soon as it has been much improved, will be able to spread over the open and continuous area, and will thus come into competition with many other forms. Moreover, great areas, though now continuous, will often, owing to former oscillations of level, have existed in a broken condition, so that the good effects of isolation will generally, to a certain extent, have concurred. Finally, I conclude that, although small isolated areas have been in some respects highly favourable for the production of new species, yet that the course of modification will generally have been more rapid on large areas; and what is more important, that the new forms produced on large areas, which already have been victorious over many competitors, will be those that will spread most widely, and will give rise to the greatest number of new varieties and species. They will thus play a more important part in the changing history of the organic world. In accordance with this view, we can, perhaps, understand some facts which will be again alluded to in our chapter on Geographical Distribution; for instance, the fact of the productions of the smaller continent of Australia now yielding before those of the larger Europaeo-Asiatic area. Thus, also, it is that continental productions have everywhere become so largely naturalised on islands. On a small island, the race for life will have been less severe, and there will have been less modification and less extermination. Hence, we can understand how it is that the flora of Madeira, according to Oswald Heer, resembles to a certain extent the extinct tertiary flora of Europe. All fresh water basins, taken together, make a small area compared with that of the sea or of the land. Consequently, the competition between fresh water productions will have been less severe than elsewhere; new forms will have been more slowly produced, and old forms more slowly exterminated. And it is in fresh water basins that we find seven genera of Ganoid fishes, remnants of a once preponderant order: and in fresh water we find some of the most anomalous forms now known in the world, as the Ornithorhynchus and Lepidosiren, which, like fossils, connect to a certain extent orders at present widely separated in the natural scale. These anomalous forms may be called living fossils; they have endured to the present day, from having inhabited a confined area, and from having been exposed to less varied, and therefore less severe, competition. To sum up, as far as the extreme intricacy of the subject permits, the circumstances favourable and unfavourable for the production of new species through natural selection. I conclude that for terrestrial productions a large continental area, which has undergone many oscillations of level, will have been the most favourable for the production of many new forms of life, fitted to endure for a long time and to spread widely. While the area existed as a continent the inhabitants will have been numerous in individuals and kinds, and will have been subjected to severe competition. When converted by subsidence into large separate islands there will still have existed many individuals of the same species on each island: intercrossing on the confines of the range of each new species will have been checked: after physical changes of any kind immigration will have been prevented, so that new places in the polity of each island will have had to be filled up by the modification of the old inhabitants; and time will have been allowed for the varieties in each to become well modified and perfected. When, by renewed elevation, the islands were reconverted into a continental area, there will again have been very severe competition; the most favoured or improved varieties will have been enabled to spread; there will have been much extinction of the less improved forms, and the relative proportional numbers of the various inhabitants of the reunited continent will again have been changed; and again there will have been a fair field for natural selection to improve still further the inhabitants, and thus to produce new species. That natural selection generally act with extreme slowness I fully admit. It can act only when there are places in the natural polity of a district which can be better occupied by the modification of some of its existing inhabitants. The occurrence of such places will often depend on physical changes, which generally take place very slowly, and on the immigration of better adapted forms being prevented. As some few of the old inhabitants become modified the mutual relations of others will often be disturbed; and this will create new places, ready to be filled up by better adapted forms; but all this will take place very slowly. Although all the individuals of the same species differ in some slight degree from each other, it would often be long before differences of the right nature in various parts of the organisation might occur. The result would often be greatly retarded by free intercrossing. Many will exclaim that these several causes are amply sufficient to neutralise the power of natural selection. I do not believe so. But I do believe that natural selection will generally act very slowly, only at long intervals of time, and only on a few of the inhabitants of the same region. I further believe that these slow, intermittent results accord well with what geology tells us of the rate and manner at which the inhabitants of the world have changed. Slow though the process of selection may be, if feeble man can do much by artificial selection, I can see no limit to the amount of change, to the beauty and complexity of the coadaptations between all organic beings, one with another and with their physical conditions of life, which may have been effected in the long course of time through nature's power of selection, that is by the survival of the fittest. EXTINCTION CAUSED BY NATURAL SELECTION. This subject will be more fully discussed in our chapter on Geology; but it must here be alluded to from being intimately connected with natural selection. Natural selection acts solely through the preservation of variations in some way advantageous, which consequently endure. Owing to the high geometrical rate of increase of all organic beings, each area is already fully stocked with inhabitants, and it follows from this, that as the favoured forms increase in number, so, generally, will the less favoured decrease and become rare. Rarity, as geology tells us, is the precursor to extinction. We can see that any form which is represented by few individuals will run a good chance of utter extinction, during great fluctuations in the nature or the seasons, or from a temporary increase in the number of its enemies. But we may go further than this; for as new forms are produced, unless we admit that specific forms can go on indefinitely increasing in number, many old forms must become extinct. That the number of specific forms has not indefinitely increased, geology plainly tells us; and we shall presently attempt to show why it is that the number of species throughout the world has not become immeasurably great. We have seen that the species which are most numerous in individuals have the best chance of producing favourable variations within any given period. We have evidence of this, in the facts stated in the second chapter, showing that it is the common and diffused or dominant species which offer the greatest number of recorded varieties. Hence, rare species will be less quickly modified or improved within any given period; they will consequently be beaten in the race for life by the modified and improved descendants of the commoner species. From these several considerations I think it inevitably follows, that as new species in the course of time are formed through natural selection, others will become rarer and rarer, and finally extinct. The forms which stand in closest competition with those undergoing modification and improvement, will naturally suffer most. And we have seen in the chapter on the Struggle for Existence that it is the most closely-allied forms,--varieties of the same species, and species of the same genus or related genera,--which, from having nearly the same structure, constitution and habits, generally come into the severest competition with each other. Consequently, each new variety or species, during the progress of its formation, will generally press hardest on its nearest kindred, and tend to exterminate them. We see the same process of extermination among our domesticated productions, through the selection of improved forms by man. Many curious instances could be given showing how quickly new breeds of cattle, sheep and other animals, and varieties of flowers, take the place of older and inferior kinds. In Yorkshire, it is historically known that the ancient black cattle were displaced by the long-horns, and that these "were swept away by the short-horns" (I quote the words of an agricultural writer) "as if by some murderous pestilence." DIVERGENCE OF CHARACTER. The principle, which I have designated by this term, is of high importance, and explains, as I believe, several important facts. In the first place, varieties, even strongly-marked ones, though having somewhat of the character of species--as is shown by the hopeless doubts in many cases how to rank them--yet certainly differ far less from each other than do good and distinct species. Nevertheless according to my view, varieties are species in the process of formation, or are, as I have called them, incipient species. How, then, does the lesser difference between varieties become augmented into the greater difference between species? That this does habitually happen, we must infer from most of the innumerable species throughout nature presenting well-marked differences; whereas varieties, the supposed prototypes and parents of future well-marked species, present slight and ill-defined differences. Mere chance, as we may call it, might cause one variety to differ in some character from its parents, and the offspring of this variety again to differ from its parent in the very same character and in a greater degree; but this alone would never account for so habitual and large a degree of difference as that between the species of the same genus. As has always been my practice, I have sought light on this head from our domestic productions. We shall here find something analogous. It will be admitted that the production of races so different as short-horn and Hereford cattle, race and cart horses, the several breeds of pigeons, etc., could never have been effected by the mere chance accumulation of similar variations during many successive generations. In practice, a fancier is, for instance, struck by a pigeon having a slightly shorter beak; another fancier is struck by a pigeon having a rather longer beak; and on the acknowledged principle that "fanciers do not and will not admire a medium standard, but like extremes," they both go on (as has actually occurred with the sub-breeds of the tumbler-pigeon) choosing and breeding from birds with longer and longer beaks, or with shorter and shorter beaks. Again, we may suppose that at an early period of history, the men of one nation or district required swifter horses, while those of another required stronger and bulkier horses. The early differences would be very slight; but, in the course of time, from the continued selection of swifter horses in the one case, and of stronger ones in the other, the differences would become greater, and would be noted as forming two sub-breeds. Ultimately after the lapse of centuries, these sub-breeds would become converted into two well-established and distinct breeds. As the differences became greater, the inferior animals with intermediate characters, being neither very swift nor very strong, would not have been used for breeding, and will thus have tended to disappear. Here, then, we see in man's productions the action of what may be called the principle of divergence, causing differences, at first barely appreciable, steadily to increase, and the breeds to diverge in character, both from each other and from their common parent. But how, it may be asked, can any analogous principle apply in nature? I believe it can and does apply most efficiently (though it was a long time before I saw how), from the simple circumstance that the more diversified the descendants from any one species become in structure, constitution, and habits, by so much will they be better enabled to seize on many and widely diversified places in the polity of nature, and so be enabled to increase in numbers. We can clearly discern this in the case of animals with simple habits. Take the case of a carnivorous quadruped, of which the number that can be supported in any country has long ago arrived at its full average. If its natural power of increase be allowed to act, it can succeed in increasing (the country not undergoing any change in conditions) only by its varying descendants seizing on places at present occupied by other animals: some of them, for instance, being enabled to feed on new kinds of prey, either dead or alive; some inhabiting new stations, climbing trees, frequenting water, and some perhaps becoming less carnivorous. The more diversified in habits and structure the descendants of our carnivorous animals become, the more places they will be enabled to occupy. What applies to one animal will apply throughout all time to all animals--that is, if they vary--for otherwise natural selection can effect nothing. So it will be with plants. It has been experimentally proved, that if a plot of ground be sown with one species of grass, and a similar plot be sown with several distinct genera of grasses, a greater number of plants and a greater weight of dry herbage can be raised in the latter than in the former case. The same has been found to hold good when one variety and several mixed varieties of wheat have been sown on equal spaces of ground. Hence, if any one species of grass were to go on varying, and the varieties were continually selected which differed from each other in the same manner, though in a very slight degree, as do the distinct species and genera of grasses, a greater number of individual plants of this species, including its modified descendants, would succeed in living on the same piece of ground. And we know that each species and each variety of grass is annually sowing almost countless seeds; and is thus striving, as it may be said, to the utmost to increase in number. Consequently, in the course of many thousand generations, the most distinct varieties of any one species of grass would have the best chance of succeeding and of increasing in numbers, and thus of supplanting the less distinct varieties; and varieties, when rendered very distinct from each other, take the rank of species. The truth of the principle that the greatest amount of life can be supported by great diversification of structure, is seen under many natural circumstances. In an extremely small area, especially if freely open to immigration, and where the contest between individual and individual must be very severe, we always find great diversity in its inhabitants. For instance, I found that a piece of turf, three feet by four in size, which had been exposed for many years to exactly the same conditions, supported twenty species of plants, and these belonged to eighteen genera and to eight orders, which shows how much these plants differed from each other. So it is with the plants and insects on small and uniform islets: also in small ponds of fresh water. Farmers find that they can raise more food by a rotation of plants belonging to the most different orders: nature follows what may be called a simultaneous rotation. Most of the animals and plants which live close round any small piece of ground, could live on it (supposing its nature not to be in any way peculiar), and may be said to be striving to the utmost to live there; but, it is seen, that where they come into the closest competition, the advantages of diversification of structure, with the accompanying differences of habit and constitution, determine that the inhabitants, which thus jostle each other most closely, shall, as a general rule, belong to what we call different genera and orders. The same principle is seen in the naturalisation of plants through man's agency in foreign lands. It might have been expected that the plants which would succeed in becoming naturalised in any land would generally have been closely allied to the indigenes; for these are commonly looked at as specially created and adapted for their own country. It might also, perhaps, have been expected that naturalised plants would have belonged to a few groups more especially adapted to certain stations in their new homes. But the case is very different; and Alph. de Candolle has well remarked, in his great and admirable work, that floras gain by naturalisation, proportionally with the number of the native genera and species, far more in new genera than in new species. To give a single instance: in the last edition of Dr. Asa Gray's "Manual of the Flora of the Northern United States," 260 naturalised plants are enumerated, and these belong to 162 genera. We thus see that these naturalised plants are of a highly diversified nature. They differ, moreover, to a large extent, from the indigenes, for out of the 162 naturalised genera, no less than 100 genera are not there indigenous, and thus a large proportional addition is made to the genera now living in the United States. By considering the nature of the plants or animals which have in any country struggled successfully with the indigenes, and have there become naturalised, we may gain some crude idea in what manner some of the natives would have had to be modified in order to gain an advantage over their compatriots; and we may at least infer that diversification of structure, amounting to new generic differences, would be profitable to them. The advantage of diversification of structure in the inhabitants of the same region is, in fact, the same as that of the physiological division of labour in the organs of the same individual body--a subject so well elucidated by Milne Edwards. No physiologist doubts that a stomach by being adapted to digest vegetable matter alone, or flesh alone, draws most nutriment from these substances. So in the general economy of any land, the more widely and perfectly the animals and plants are diversified for different habits of life, so will a greater number of individuals be capable of there supporting themselves. A set of animals, with their organisation but little diversified, could hardly compete with a set more perfectly diversified in structure. It may be doubted, for instance, whether the Australian marsupials, which are divided into groups differing but little from each other, and feebly representing, as Mr. Waterhouse and others have remarked, our carnivorous, ruminant, and rodent mammals, could successfully compete with these well-developed orders. In the Australian mammals, we see the process of diversification in an early and incomplete stage of development. THE PROBABLE EFFECTS OF THE ACTION OF NATURAL SELECTION THROUGH DIVERGENCE OF CHARACTER AND EXTINCTION, ON THE DESCENDANTS OF A COMMON ANCESTOR. After the foregoing discussion, which has been much compressed, we may assume that the modified descendants of any one species will succeed so much the better as they become more diversified in structure, and are thus enabled to encroach on places occupied by other beings. Now let us see how this principle of benefit being derived from divergence of character, combined with the principles of natural selection and of extinction, tends to act. The accompanying diagram will aid us in understanding this rather perplexing subject. Let A to L represent the species of a genus large in its own country; these species are supposed to resemble each other in unequal degrees, as is so generally the case in nature, and as is represented in the diagram by the letters standing at unequal distances. I have said a large genus, because as we saw in the second chapter, on an average more species vary in large genera than in small genera; and the varying species of the large genera present a greater number of varieties. We have, also, seen that the species, which are the commonest and most widely-diffused, vary more than do the rare and restricted species. Let (A) be a common, widely-diffused, and varying species, belonging to a genus large in its own country. The branching and diverging dotted lines of unequal lengths proceeding from (A), may represent its varying offspring. The variations are supposed to be extremely slight, but of the most diversified nature; they are not supposed all to appear simultaneously, but often after long intervals of time; nor are they all supposed to endure for equal periods. Only those variations which are in some way profitable will be preserved or naturally selected. And here the importance of the principle of benefit derived from divergence of character comes in; for this will generally lead to the most different or divergent variations (represented by the outer dotted lines) being preserved and accumulated by natural selection. When a dotted line reaches one of the horizontal lines, and is there marked by a small numbered letter, a sufficient amount of variation is supposed to have been accumulated to form it into a fairly well-marked variety, such as would be thought worthy of record in a systematic work. The intervals between the horizontal lines in the diagram, may represent each a thousand or more generations. After a thousand generations, species (A) is supposed to have produced two fairly well-marked varieties, namely a1 and m1. These two varieties will generally still be exposed to the same conditions which made their parents variable, and the tendency to variability is in itself hereditary; consequently they will likewise tend to vary, and commonly in nearly the same manner as did their parents. Moreover, these two varieties, being only slightly modified forms, will tend to inherit those advantages which made their parent (A) more numerous than most of the other inhabitants of the same country; they will also partake of those more general advantages which made the genus to which the parent-species belonged, a large genus in its own country. And all these circumstances are favourable to the production of new varieties. If, then, these two varieties be variable, the most divergent of their variations will generally be preserved during the next thousand generations. And after this interval, variety a1 is supposed in the diagram to have produced variety a2, which will, owing to the principle of divergence, differ more from (A) than did variety a1. Variety m1 is supposed to have produced two varieties, namely m2 and s2, differing from each other, and more considerably from their common parent (A). We may continue the process by similar steps for any length of time; some of the varieties, after each thousand generations, producing only a single variety, but in a more and more modified condition, some producing two or three varieties, and some failing to produce any. Thus the varieties or modified descendants of the common parent (A), will generally go on increasing in number and diverging in character. In the diagram the process is represented up to the ten-thousandth generation, and under a condensed and simplified form up to the fourteen-thousandth generation. But I must here remark that I do not suppose that the process ever goes on so regularly as is represented in the diagram, though in itself made somewhat irregular, nor that it goes on continuously; it is far more probable that each form remains for long periods unaltered, and then again undergoes modification. Nor do I suppose that the most divergent varieties are invariably preserved: a medium form may often long endure, and may or may not produce more than one modified descendant; for natural selection will always act according to the nature of the places which are either unoccupied or not perfectly occupied by other beings; and this will depend on infinitely complex relations. But as a general rule, the more diversified in structure the descendants from any one species can be rendered, the more places they will be enabled to seize on, and the more their modified progeny will increase. In our diagram the line of succession is broken at regular intervals by small numbered letters marking the successive forms which have become sufficiently distinct to be recorded as varieties. But these breaks are imaginary, and might have been inserted anywhere, after intervals long enough to allow the accumulation of a considerable amount of divergent variation. As all the modified descendants from a common and widely-diffused species, belonging to a large genus, will tend to partake of the same advantages which made their parent successful in life, they will generally go on multiplying in number as well as diverging in character: this is represented in the diagram by the several divergent branches proceeding from (A). The modified offspring from the later and more highly improved branches in the lines of descent, will, it is probable, often take the place of, and so destroy, the earlier and less improved branches: this is represented in the diagram by some of the lower branches not reaching to the upper horizontal lines. In some cases no doubt the process of modification will be confined to a single line of descent, and the number of modified descendants will not be increased; although the amount of divergent modification may have been augmented. This case would be represented in the diagram, if all the lines proceeding from (A) were removed, excepting that from a1 to a10. In the same way the English racehorse and English pointer have apparently both gone on slowly diverging in character from their original stocks, without either having given off any fresh branches or races. After ten thousand generations, species (A) is supposed to have produced three forms, a10, f10, and m10, which, from having diverged in character during the successive generations, will have come to differ largely, but perhaps unequally, from each other and from their common parent. If we suppose the amount of change between each horizontal line in our diagram to be excessively small, these three forms may still be only well-marked varieties; but we have only to suppose the steps in the process of modification to be more numerous or greater in amount, to convert these three forms into doubtful or at least into well-defined species: thus the diagram illustrates the steps by which the small differences distinguishing varieties are increased into the larger differences distinguishing species. By continuing the same process for a greater number of generations (as shown in the diagram in a condensed and simplified manner), we get eight species, marked by the letters between a14 and m14, all descended from (A). Thus, as I believe, species are multiplied and genera are formed. In a large genus it is probable that more than one species would vary. In the diagram I have assumed that a second species (I) has produced, by analogous steps, after ten thousand generations, either two well-marked varieties (w10 and z10) or two species, according to the amount of change supposed to be represented between the horizontal lines. After fourteen thousand generations, six new species, marked by the letters n14 to z14, are supposed to have been produced. In any genus, the species which are already very different in character from each other, will generally tend to produce the greatest number of modified descendants; for these will have the best chance of seizing on new and widely different places in the polity of nature: hence in the diagram I have chosen the extreme species (A), and the nearly extreme species (I), as those which have largely varied, and have given rise to new varieties and species. The other nine species (marked by capital letters) of our original genus, may for long but unequal periods continue to transmit unaltered descendants; and this is shown in the diagram by the dotted lines unequally prolonged upwards. But during the process of modification, represented in the diagram, another of our principles, namely that of extinction, will have played an important part. As in each fully stocked country natural selection necessarily acts by the selected form having some advantage in the struggle for life over other forms, there will be a constant tendency in the improved descendants of any one species to supplant and exterminate in each stage of descent their predecessors and their original progenitor. For it should be remembered that the competition will generally be most severe between those forms which are most nearly related to each other in habits, constitution and structure. Hence all the intermediate forms between the earlier and later states, that is between the less and more improved states of a the same species, as well as the original parent-species itself, will generally tend to become extinct. So it probably will be with many whole collateral lines of descent, which will be conquered by later and improved lines. If, however, the modified offspring of a species get into some distinct country, or become quickly adapted to some quite new station, in which offspring and progenitor do not come into competition, both may continue to exist. If, then, our diagram be assumed to represent a considerable amount of modification, species (A) and all the earlier varieties will have become extinct, being replaced by eight new species (a14 to m14); and species (I) will be replaced by six (n14 to z14) new species. But we may go further than this. The original species of our genus were supposed to resemble each other in unequal degrees, as is so generally the case in nature; species (A) being more nearly related to B, C, and D than to the other species; and species (I) more to G, H, K, L, than to the others. These two species (A and I), were also supposed to be very common and widely diffused species, so that they must originally have had some advantage over most of the other species of the genus. Their modified descendants, fourteen in number at the fourteen-thousandth generation, will probably have inherited some of the same advantages: they have also been modified and improved in a diversified manner at each stage of descent, so as to have become adapted to many related places in the natural economy of their country. It seems, therefore, extremely probable that they will have taken the places of, and thus exterminated, not only their parents (A) and (I), but likewise some of the original species which were most nearly related to their parents. Hence very few of the original species will have transmitted offspring to the fourteen-thousandth generation. We may suppose that only one (F) of the two species (E and F) which were least closely related to the other nine original species, has transmitted descendants to this late stage of descent. The new species in our diagram, descended from the original eleven species, will now be fifteen in number. Owing to the divergent tendency of natural selection, the extreme amount of difference in character between species a14 and z14 will be much greater than that between the most distinct of the original eleven species. The new species, moreover, will be allied to each other in a widely different manner. Of the eight descendants from (A) the three marked a14, q14, p14, will be nearly related from having recently branched off from a10; b14 and f14, from having diverged at an earlier period from a5, will be in some degree distinct from the three first-named species; and lastly, o14, e14, and m14, will be nearly related one to the other, but, from having diverged at the first commencement of the process of modification, will be widely different from the other five species, and may constitute a sub-genus or a distinct genus. The six descendants from (I) will form two sub-genera or genera. But as the original species (I) differed largely from (A), standing nearly at the extreme end of the original genus, the six descendants from (I) will, owing to inheritance alone, differ considerably from the eight descendants from (A); the two groups, moreover, are supposed to have gone on diverging in different directions. The intermediate species, also (and this is a very important consideration), which connected the original species (A) and (I), have all become, except (F), extinct, and have left no descendants. Hence the six new species descended from (I), and the eight descendants from (A), will have to be ranked as very distinct genera, or even as distinct sub-families. Thus it is, as I believe, that two or more genera are produced by descent with modification, from two or more species of the same genus. And the two or more parent-species are supposed to be descended from some one species of an earlier genus. In our diagram this is indicated by the broken lines beneath the capital letters, converging in sub-branches downwards towards a single point; this point represents a species, the supposed progenitor of our several new sub-genera and genera. It is worth while to reflect for a moment on the character of the new species F14, which is supposed not to have diverged much in character, but to have retained the form of (F), either unaltered or altered only in a slight degree. In this case its affinities to the other fourteen new species will be of a curious and circuitous nature. Being descended from a form that stood between the parent-species (A) and (I), now supposed to be extinct and unknown, it will be in some degree intermediate in character between the two groups descended from these two species. But as these two groups have gone on diverging in character from the type of their parents, the new species (F14) will not be directly intermediate between them, but rather between types of the two groups; and every naturalist will be able to call such cases before his mind. In the diagram each horizontal line has hitherto been supposed to represent a thousand generations, but each may represent a million or more generations; it may also represent a section of the successive strata of the earth's crust including extinct remains. We shall, when we come to our chapter on geology, have to refer again to this subject, and I think we shall then see that the diagram throws light on the affinities of extinct beings, which, though generally belonging to the same orders, families, or genera, with those now living, yet are often, in some degree, intermediate in character between existing groups; and we can understand this fact, for the extinct species lived at various remote epochs when the branching lines of descent had diverged less. I see no reason to limit the process of modification, as now explained, to the formation of genera alone. If, in the diagram, we suppose the amount of change represented by each successive group of diverging dotted lines to be great, the forms marked a14 to p14, those marked b14 and f14, and those marked o14 to m14, will form three very distinct genera. We shall also have two very distinct genera descended from (I), differing widely from the descendants of (A). These two groups of genera will thus form two distinct families, or orders, according to the amount of divergent modification supposed to be represented in the diagram. And the two new families, or orders, are descended from two species of the original genus; and these are supposed to be descended from some still more ancient and unknown form. We have seen that in each country it is the species belonging to the larger genera which oftenest present varieties or incipient species. This, indeed, might have been expected; for as natural selection acts through one form having some advantage over other forms in the struggle for existence, it will chiefly act on those which already have some advantage; and the largeness of any group shows that its species have inherited from a common ancestor some advantage in common. Hence, the struggle for the production of new and modified descendants will mainly lie between the larger groups, which are all trying to increase in number. One large group will slowly conquer another large group, reduce its number, and thus lessen its chance of further variation and improvement. Within the same large group, the later and more highly perfected sub-groups, from branching out and seizing on many new places in the polity of nature, will constantly tend to supplant and destroy the earlier and less improved sub-groups. Small and broken groups and sub-groups will finally disappear. Looking to the future, we can predict that the groups of organic beings which are now large and triumphant, and which are least broken up, that is, which have as yet suffered least extinction, will, for a long period, continue to increase. But which groups will ultimately prevail, no man can predict; for we know that many groups, formerly most extensively developed, have now become extinct. Looking still more remotely to the future, we may predict that, owing to the continued and steady increase of the larger groups, a multitude of smaller groups will become utterly extinct, and leave no modified descendants; and consequently that, of the species living at any one period, extremely few will transmit descendants to a remote futurity. I shall have to return to this subject in the chapter on classification, but I may add that as, according to this view, extremely few of the more ancient species have transmitted descendants to the present day, and, as all the descendants of the same species form a class, we can understand how it is that there exist so few classes in each main division of the animal and vegetable kingdoms. Although few of the most ancient species have left modified descendants, yet, at remote geological periods, the earth may have been almost as well peopled with species of many genera, families, orders and classes, as at the present day. ON THE DEGREE TO WHICH ORGANISATION TENDS TO ADVANCE. Natural selection acts exclusively by the preservation and accumulation of variations, which are beneficial under the organic and inorganic conditions to which each creature is exposed at all periods of life. The ultimate result is that each creature tends to become more and more improved in relation to its conditions. This improvement inevitably leads to the gradual advancement of the organisation of the greater number of living beings throughout the world. But here we enter on a very intricate subject, for naturalists have not defined to each other's satisfaction what is meant by an advance in organisation. Among the vertebrata the degree of intellect and an approach in structure to man clearly come into play. It might be thought that the amount of change which the various parts and organs pass through in their development from embryo to maturity would suffice as a standard of comparison; but there are cases, as with certain parasitic crustaceans, in which several parts of the structure become less perfect, so that the mature animal cannot be called higher than its larva. Von Baer's standard seems the most widely applicable and the best, namely, the amount of differentiation of the parts of the same organic being, in the adult state, as I should be inclined to add, and their specialisation for different functions; or, as Milne Edwards would express it, the completeness of the division of physiological labour. But we shall see how obscure this subject is if we look, for instance, to fishes, among which some naturalists rank those as highest which, like the sharks, approach nearest to amphibians; while other naturalists rank the common bony or teleostean fishes as the highest, inasmuch as they are most strictly fish-like, and differ most from the other vertebrate classes. We see still more plainly the obscurity of the subject by turning to plants, among which the standard of intellect is of course quite excluded; and here some botanists rank those plants as highest which have every organ, as sepals, petals, stamens and pistils, fully developed in each flower; whereas other botanists, probably with more truth, look at the plants which have their several organs much modified and reduced in number as the highest. If we take as the standard of high organisation, the amount of differentiation and specialisation of the several organs in each being when adult (and this will include the advancement of the brain for intellectual purposes), natural selection clearly leads towards this standard: for all physiologists admit that the specialisation of organs, inasmuch as in this state they perform their functions better, is an advantage to each being; and hence the accumulation of variations tending towards specialisation is within the scope of natural selection. On the other hand, we can see, bearing in mind that all organic beings are striving to increase at a high ratio and to seize on every unoccupied or less well occupied place in the economy of nature, that it is quite possible for natural selection gradually to fit a being to a situation in which several organs would be superfluous or useless: in such cases there would be retrogression in the scale of organisation. Whether organisation on the whole has actually advanced from the remotest geological periods to the present day will be more conveniently discussed in our chapter on Geological Succession. But it may be objected that if all organic beings thus tend to rise in the scale, how is it that throughout the world a multitude of the lowest forms still exist; and how is it that in each great class some forms are far more highly developed than others? Why have not the more highly developed forms every where supplanted and exterminated the lower? Lamarck, who believed in an innate and inevitable tendency towards perfection in all organic beings, seems to have felt this difficulty so strongly that he was led to suppose that new and simple forms are continually being produced by spontaneous generation. Science has not as yet proved the truth of this belief, whatever the future may reveal. On our theory the continued existence of lowly organisms offers no difficulty; for natural selection, or the survival of the fittest, does not necessarily include progressive development--it only takes advantage of such variations as arise and are beneficial to each creature under its complex relations of life. And it may be asked what advantage, as far as we can see, would it be to an infusorian animalcule--to an intestinal worm--or even to an earth-worm, to be highly organised. If it were no advantage, these forms would be left, by natural selection, unimproved or but little improved, and might remain for indefinite ages in their present lowly condition. And geology tells us that some of the lowest forms, as the infusoria and rhizopods, have remained for an enormous period in nearly their present state. But to suppose that most of the many now existing low forms have not in the least advanced since the first dawn of life would be extremely rash; for every naturalist who has dissected some of the beings now ranked as very low in the scale, must have been struck with their really wondrous and beautiful organisation. Nearly the same remarks are applicable, if we look to the different grades of organisation within the same great group; for instance, in the vertebrata, to the co-existence of mammals and fish--among mammalia, to the co-existence of man and the ornithorhynchus--among fishes, to the co-existence of the shark and the lancelet (Amphioxus), which latter fish in the extreme simplicity of its structure approaches the invertebrate classes. But mammals and fish hardly come into competition with each other; the advancement of the whole class of mammals, or of certain members in this class, to the highest grade would not lead to their taking the place of fishes. Physiologists believe that the brain must be bathed by warm blood to be highly active, and this requires aerial respiration; so that warm-blooded mammals when inhabiting the water lie under a disadvantage in having to come continually to the surface to breathe. With fishes, members of the shark family would not tend to supplant the lancelet; for the lancelet, as I hear from Fritz Muller, has as sole companion and competitor on the barren sandy shore of South Brazil, an anomalous annelid. The three lowest orders of mammals, namely, marsupials, edentata, and rodents, co-exist in South America in the same region with numerous monkeys, and probably interfere little with each other. Although organisation, on the whole, may have advanced and be still advancing throughout the world, yet the scale will always present many degrees of perfection; for the high advancement of certain whole classes, or of certain members of each class, does not at all necessarily lead to the extinction of those groups with which they do not enter into close competition. In some cases, as we shall hereafter see, lowly organised forms appear to have been preserved to the present day, from inhabiting confined or peculiar stations, where they have been subjected to less severe competition, and where their scanty numbers have retarded the chance of favourable variations arising. Finally, I believe that many lowly organised forms now exist throughout the world, from various causes. In some cases variations or individual differences of a favourable nature may never have arisen for natural selection to act on and accumulate. In no case, probably, has time sufficed for the utmost possible amount of development. In some few cases there has been what we must call retrogression or organisation. But the main cause lies in the fact that under very simple conditions of life a high organisation would be of no service--possibly would be of actual disservice, as being of a more delicate nature, and more liable to be put out of order and injured. Looking to the first dawn of life, when all organic beings, as we may believe, presented the simplest structure, how, it has been asked, could the first step in the advancement or differentiation of parts have arisen? Mr. Herbert Spencer would probably answer that, as soon as simple unicellular organisms came by growth or division to be compounded of several cells, or became attached to any supporting surface, his law "that homologous units of any order become differentiated in proportion as their relations to incident forces become different" would come into action. But as we have no facts to guide us, speculation on the subject is almost useless. It is, however, an error to suppose that there would be no struggle for existence, and, consequently, no natural selection, until many forms had been produced: variations in a single species inhabiting an isolated station might be beneficial, and thus the whole mass of individuals might be modified, or two distinct forms might arise. But, as I remarked towards the close of the introduction, no one ought to feel surprise at much remaining as yet unexplained on the origin of species, if we make due allowance for our profound ignorance on the mutual relations of the inhabitants of the world at the present time, and still more so during past ages. CONVERGENCE OF CHARACTER. Mr. H.C. Watson thinks that I have overrated the importance of divergence of character (in which, however, he apparently believes), and that convergence, as it may be called, has likewise played a part. If two species belonging to two distinct though allied genera, had both produced a large number of new and divergent forms, it is conceivable that these might approach each other so closely that they would have all to be classed under the same genus; and thus the descendants of two distinct genera would converge into one. But it would in most cases be extremely rash to attribute to convergence a close and general similarity of structure in the modified descendants of widely distinct forms. The shape of a crystal is determined solely by the molecular forces, and it is not surprising that dissimilar substances should sometimes assume the same form; but with organic beings we should bear in mind that the form of each depends on an infinitude of complex relations, namely on the variations which have arisen, these being due to causes far too intricate to be followed out--on the nature of the variations which have been preserved or selected, and this depends on the surrounding physical conditions, and in a still higher degree on the surrounding organisms with which each being has come into competition--and lastly, on inheritance (in itself a fluctuating element) from innumerable progenitors, all of which have had their forms determined through equally complex relations. It is incredible that the descendants of two organisms, which had originally differed in a marked manner, should ever afterwards converge so closely as to lead to a near approach to identity throughout their whole organisation. If this had occurred, we should meet with the same form, independently of genetic connection, recurring in widely separated geological formations; and the balance of evidence is opposed to any such an admission. Mr. Watson has also objected that the continued action of natural selection, together with divergence of character, would tend to make an indefinite number of specific forms. As far as mere inorganic conditions are concerned, it seems probable that a sufficient number of species would soon become adapted to all considerable diversities of heat, moisture, etc.; but I fully admit that the mutual relations of organic beings are more important; and as the number of species in any country goes on increasing, the organic conditions of life must become more and more complex. Consequently there seems at first no limit to the amount of profitable diversification of structure, and therefore no limit to the number of species which might be produced. We do not know that even the most prolific area is fully stocked with specific forms: at the Cape of Good Hope and in Australia, which support such an astonishing number of species, many European plants have become naturalised. But geology shows us, that from an early part of the tertiary period the number of species of shells, and that from the middle part of this same period, the number of mammals has not greatly or at all increased. What then checks an indefinite increase in the number of species? The amount of life (I do not mean the number of specific forms) supported on an area must have a limit, depending so largely as it does on physical conditions; therefore, if an area be inhabited by very many species, each or nearly each species will be represented by few individuals; and such species will be liable to extermination from accidental fluctuations in the nature of the seasons or in the number of their enemies. The process of extermination in such cases would be rapid, whereas the production of new species must always be slow. Imagine the extreme case of as many species as individuals in England, and the first severe winter or very dry summer would exterminate thousands on thousands of species. Rare species, and each species will become rare if the number of species in any country becomes indefinitely increased, will, on the principal often explained, present within a given period few favourable variations; consequently, the process of giving birth to new specific forms would thus be retarded. When any species becomes very rare, close interbreeding will help to exterminate it; authors have thought that this comes into play in accounting for the deterioration of the aurochs in Lithuania, of red deer in Scotland and of bears in Norway, etc. Lastly, and this I am inclined to think is the most important element, a dominant species, which has already beaten many competitors in its own home, will tend to spread and supplant many others. Alph. de Candolle has shown that those species which spread widely tend generally to spread VERY widely, consequently they will tend to supplant and exterminate several species in several areas, and thus check the inordinate increase of specific forms throughout the world. Dr. Hooker has recently shown that in the southeast corner of Australia, where, apparently, there are many invaders from different quarters of the globe, the endemic Australian species have been greatly reduced in number. How much weight to attribute to these several considerations I will not pretend to say; but conjointly they must limit in each country the tendency to an indefinite augmentation of specific forms. SUMMARY OF CHAPTER. If under changing conditions of life organic beings present individual differences in almost every part of their structure, and this cannot be disputed; if there be, owing to their geometrical rate of increase, a severe struggle for life at some age, season or year, and this certainly cannot be disputed; then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of life, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, it would be a most extraordinary fact if no variations had ever occurred useful to each being's own welfare, in the same manner as so many variations have occurred useful to man. But if variations useful to any organic being ever do occur, assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance, these will tend to produce offspring similarly characterised. This principle of preservation, or the survival of the fittest, I have called natural selection. It leads to the improvement of each creature in relation to its organic and inorganic conditions of life; and consequently, in most cases, to what must be regarded as an advance in organisation. Nevertheless, low and simple forms will long endure if well fitted for their simple conditions of life. Natural selection, on the principle of qualities being inherited at corresponding ages, can modify the egg, seed, or young as easily as the adult. Among many animals sexual selection will have given its aid to ordinary selection by assuring to the most vigorous and best adapted males the greatest number of offspring. Sexual selection will also give characters useful to the males alone in their struggles or rivalry with other males; and these characters will be transmitted to one sex or to both sexes, according to the form of inheritance which prevails. Whether natural selection has really thus acted in adapting the various forms of life to their several conditions and stations, must be judged by the general tenour and balance of evidence given in the following chapters. But we have already seen how it entails extinction; and how largely extinction has acted in the world's history, geology plainly declares. Natural selection, also, leads to divergence of character; for the more organic beings diverge in structure, habits and constitution, by so much the more can a large number be supported on the area, of which we see proof by looking to the inhabitants of any small spot, and to the productions naturalised in foreign lands. Therefore, during the modification of the descendants of any one species, and during the incessant struggle of all species to increase in numbers, the more diversified the descendants become, the better will be their chance of success in the battle for life. Thus the small differences distinguishing varieties of the same species, steadily tend to increase, till they equal the greater differences between species of the same genus, or even of distinct genera. We have seen that it is the common, the widely diffused, and widely ranging species, belonging to the larger genera within each class, which vary most; and these tend to transmit to their modified offspring that superiority which now makes them dominant in their own countries. Natural selection, as has just been remarked, leads to divergence of character and to much extinction of the less improved and intermediate forms of life. On these principles, the nature of the affinities, and the generally well defined distinctions between the innumerable organic beings in each class throughout the world, may be explained. It is a truly wonderful fact--the wonder of which we are apt to overlook from familiarity--that all animals and all plants throughout all time and space should be related to each other in groups, subordinate to groups, in the manner which we everywhere behold--namely, varieties of the same species most closely related, species of the same genus less closely and unequally related, forming sections and sub-genera, species of distinct genera much less closely related, and genera related in different degrees, forming sub-families, families, orders, sub-classes, and classes. The several subordinate groups in any class cannot be ranked in a single file, but seem clustered round points, and these round other points, and so on in almost endless cycles. If species had been independently created, no explanation would have been possible of this kind of classification; but it is explained through inheritance and the complex action of natural selection, entailing extinction and divergence of character, as we have seen illustrated in the diagram. The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produced during former years may represent the long succession of extinct species. At each period of growth all the growing twigs have tried to branch out on all sides, and to overtop and kill the surrounding twigs and branches, in the same manner as species and groups of species have at all times overmastered other species in the great battle for life. The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was young, budding twigs; and this connexion of the former and present buds by ramifying branches may well represent the classification of all extinct and living species in groups subordinate to groups. Of the many twigs which flourished when the tree was a mere bush, only two or three, now grown into great branches, yet survive and bear the other branches; so with the species which lived during long-past geological periods, very few have left living and modified descendants. From the first growth of the tree, many a limb and branch has decayed and dropped off; and these fallen branches of various sizes may represent those whole orders, families, and genera which have now no living representatives, and which are known to us only in a fossil state. As we here and there see a thin, straggling branch springing from a fork low down in a tree, and which by some chance has been favoured and is still alive on its summit, so we occasionally see an animal like the Ornithorhynchus or Lepidosiren, which in some small degree connects by its affinities two large branches of life, and which has apparently been saved from fatal competition by having inhabited a protected station. As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever-branching and beautiful ramifications. CHAPTER V. LAWS OF VARIATION. Effects of changed conditions--Use and disuse, combined with natural selection; organs of flight and of vision--Acclimatisation--Correlated variation--Compensation and economy of growth--False correlations--Multiple, rudimentary, and lowly organised structures variable--Parts developed in an unusual manner are highly variable: specific characters more variable than generic: secondary sexual characters variable--Species of the same genus vary in an analogous manner--Reversions to long-lost characters--Summary. I have hitherto sometimes spoken as if the variations--so common and multiform with organic beings under domestication, and in a lesser degree with those under nature--were due to chance. This, of course is a wholly incorrect expression, but it serves to acknowledge plainly our ignorance of the cause of each particular variation. Some authors believe it to be as much the function of the reproductive system to produce individual differences, or slight deviations of structure, as to make the child like its parents. But the fact of variations and monstrosities occurring much more frequently under domestication than under nature, and the greater variability of species having wide ranges than of those with restricted ranges, lead to the conclusion that variability is generally related to the conditions of life to which each species has been exposed during several successive generations. In the first chapter I attempted to show that changed conditions act in two ways, directly on the whole organisation or on certain parts alone, and indirectly through the reproductive system. In all cases there are two factors, the nature of the organism, which is much the most important of the two, and the nature of the conditions. The direct action of changed conditions leads to definite or indefinite results. In the latter case the organisation seems to become plastic, and we have much fluctuating variability. In the former case the nature of the organism is such that it yields readily, when subjected to certain conditions, and all, or nearly all, the individuals become modified in the same way. It is very difficult to decide how far changed conditions, such as of climate, food, etc., have acted in a definite manner. There is reason to believe that in the course of time the effects have been greater than can be proved by clear evidence. But we may safely conclude that the innumerable complex co-adaptations of structure, which we see throughout nature between various organic beings, cannot be attributed simply to such action. In the following cases the conditions seem to have produced some slight definite effect: E. Forbes asserts that shells at their southern limit, and when living in shallow water, are more brightly coloured than those of the same species from further north or from a greater depth; but this certainly does not always hold good. Mr. Gould believes that birds of the same species are more brightly coloured under a clear atmosphere, than when living near the coast or on islands; and Wollaston is convinced that residence near the sea affects the colours of insects. Moquin-Tandon gives a list of plants which, when growing near the sea-shore, have their leaves in some degree fleshy, though not elsewhere fleshy. These slightly varying organisms are interesting in as far as they present characters analogous to those possessed by the species which are confined to similar conditions. When a variation is of the slightest use to any being, we cannot tell how much to attribute to the accumulative action of natural selection, and how much to the definite action of the conditions of life. Thus, it is well known to furriers that animals of the same species have thicker and better fur the further north they live; but who can tell how much of this difference may be due to the warmest-clad individuals having been favoured and preserved during many generations, and how much to the action of the severe climate? For it would appear that climate has some direct action on the hair of our domestic quadrupeds. Instances could be given of similar varieties being produced from the same species under external conditions of life as different as can well be conceived; and, on the other hand, of dissimilar varieties being produced under apparently the same external conditions. Again, innumerable instances are known to every naturalist, of species keeping true, or not varying at all, although living under the most opposite climates. Such considerations as these incline me to lay less weight on the direct action of the surrounding conditions, than on a tendency to vary, due to causes of which we are quite ignorant. In one sense the conditions of life may be said, not only to cause variability, either directly or indirectly, but likewise to include natural selection, for the conditions determine whether this or that variety shall survive. But when man is the selecting agent, we clearly see that the two elements of change are distinct; variability is in some manner excited, but it is the will of man which accumulates the variations in certain direction; and it is this latter agency which answers to the survival of the fittest under nature. EFFECTS OF THE INCREASED USE AND DISUSE OF PARTS, AS CONTROLLED BY NATURAL SELECTION. From the facts alluded to in the first chapter, I think there can be no doubt that use in our domestic animals has strengthened and enlarged certain parts, and disuse diminished them; and that such modifications are inherited. Under free nature we have no standard of comparison by which to judge of the effects of long-continued use or disuse, for we know not the parent-forms; but many animals possess structures which can be best explained by the effects of disuse. As Professor Owen has remarked, there is no greater anomaly in nature than a bird that cannot fly; yet there are several in this state. The logger-headed duck of South America can only flap along the surface of the water, and has its wings in nearly the same condition as the domestic Aylesbury duck: it is a remarkable fact that the young birds, according to Mr. Cunningham, can fly, while the adults have lost this power. As the larger ground-feeding birds seldom take flight except to escape danger, it is probable that the nearly wingless condition of several birds, now inhabiting or which lately inhabited several oceanic islands, tenanted by no beasts of prey, has been caused by disuse. The ostrich indeed inhabits continents, and is exposed to danger from which it cannot escape by flight, but it can defend itself, by kicking its enemies, as efficiently as many quadrupeds. We may believe that the progenitor of the ostrich genus had habits like those of the bustard, and that, as the size and weight of its body were increased during successive generations, its legs were used more and its wings less, until they became incapable of flight. Kirby has remarked (and I have observed the same fact) that the anterior tarsi, or feet, of many male dung-feeding beetles are often broken off; he examined seventeen specimens in his own collection, and not one had even a relic left. In the Onites apelles the tarsi are so habitually lost that the insect has been described as not having them. In some other genera they are present, but in a rudimentary condition. In the Ateuchus or sacred beetle of the Egyptians, they are totally deficient. The evidence that accidental mutilations can be inherited is at present not decisive; but the remarkable cases observed by Brown-Sequard in guinea-pigs, of the inherited effects of operations, should make us cautious in denying this tendency. Hence, it will perhaps be safest to look at the entire absence of the anterior tarsi in Ateuchus, and their rudimentary condition in some other genera, not as cases of inherited mutilations, but as due to the effects of long-continued disuse; for as many dung-feeding beetles are generally found with their tarsi lost, this must happen early in life; therefore the tarsi cannot be of much importance or be much used by these insects. In some cases we might easily put down to disuse modifications of structure which are wholly, or mainly due to natural selection. Mr. Wollaston has discovered the remarkable fact that 200 beetles, out of the 550 species (but more are now known) inhabiting Madeira, are so far deficient in wings that they cannot fly; and that, of the twenty-nine endemic genera, no less than twenty-three have all their species in this condition! Several facts, namely, that beetles in many parts of the world are very frequently blown to sea and perish; that the beetles in Madeira, as observed by Mr. Wollaston, lie much concealed, until the wind lulls and the sun shines; that the proportion of wingless beetles is larger on the exposed Desertas than in Madeira itself; and especially the extraordinary fact, so strongly insisted on by Mr. Wollaston, that certain large groups of beetles, elsewhere excessively numerous, which absolutely require the use of their wings, are here almost entirely absent. These several considerations make me believe that the wingless condition of so many Madeira beetles is mainly due to the action of natural selection, combined probably with disuse. For during many successive generations each individual beetle which flew least, either from its wings having been ever so little less perfectly developed or from indolent habit, will have had the best chance of surviving from not being blown out to sea; and, on the other hand, those beetles which most readily took to flight would oftenest have been blown to sea, and thus destroyed. The insects in Madeira which are not ground-feeders, and which, as certain flower-feeding coleoptera and lepidoptera, must habitually use their wings to gain their subsistence, have, as Mr. Wollaston suspects, their wings not at all reduced, but even enlarged. This is quite compatible with the action of natural selection. For when a new insect first arrived on the island, the tendency of natural selection to enlarge or to reduce the wings, would depend on whether a greater number of individuals were saved by successfully battling with the winds, or by giving up the attempt and rarely or never flying. As with mariners shipwrecked near a coast, it would have been better for the good swimmers if they had been able to swim still further, whereas it would have been better for the bad swimmers if they had not been able to swim at all and had stuck to the wreck. The eyes of moles and of some burrowing rodents are rudimentary in size, and in some cases are quite covered by skin and fur. This state of the eyes is probably due to gradual reduction from disuse, but aided perhaps by natural selection. In South America, a burrowing rodent, the tuco-tuco, or Ctenomys, is even more subterranean in its habits than the mole; and I was assured by a Spaniard, who had often caught them, that they were frequently blind. One which I kept alive was certainly in this condition, the cause, as appeared on dissection, having been inflammation of the nictitating membrane. As frequent inflammation of the eyes must be injurious to any animal, and as eyes are certainly not necessary to animals having subterranean habits, a reduction in their size, with the adhesion of the eyelids and growth of fur over them, might in such case be an advantage; and if so, natural selection would aid the effects of disuse. It is well known that several animals, belonging to the most different classes, which inhabit the caves of Carniola and Kentucky, are blind. In some of the crabs the foot-stalk for the eye remains, though the eye is gone; the stand for the telescope is there, though the telescope with its glasses has been lost. As it is difficult to imagine that eyes, though useless, could be in any way injurious to animals living in darkness, their loss may be attributed to disuse. In one of the blind animals, namely, the cave-rat (Neotoma), two of which were captured by Professor Silliman at above half a mile distance from the mouth of the cave, and therefore not in the profoundest depths, the eyes were lustrous and of large size; and these animals, as I am informed by Professor Silliman, after having been exposed for about a month to a graduated light, acquired a dim perception of objects. It is difficult to imagine conditions of life more similar than deep limestone caverns under a nearly similar climate; so that, in accordance with the old view of the blind animals having been separately created for the American and European caverns, very close similarity in their organisation and affinities might have been expected. This is certainly not the case if we look at the two whole faunas; with respect to the insects alone, Schiodte has remarked: "We are accordingly prevented from considering the entire phenomenon in any other light than something purely local, and the similarity which is exhibited in a few forms between the Mammoth Cave (in Kentucky) and the caves in Carniola, otherwise than as a very plain expression of that analogy which subsists generally between the fauna of Europe and of North America." On my view we must suppose that American animals, having in most cases ordinary powers of vision, slowly migrated by successive generations from the outer world into the deeper and deeper recesses of the Kentucky caves, as did European animals into the caves of Europe. We have some evidence of this gradation of habit; for, as Schiodte remarks: "We accordingly look upon the subterranean faunas as small ramifications which have penetrated into the earth from the geographically limited faunas of the adjacent tracts, and which, as they extended themselves into darkness, have been accommodated to surrounding circumstances. Animals not far remote from ordinary forms, prepare the transition from light to darkness. Next follow those that are constructed for twilight; and, last of all, those destined for total darkness, and whose formation is quite peculiar." These remarks of Schiodte's it should be understood, apply not to the same, but to distinct species. By the time that an animal had reached, after numberless generations, the deepest recesses, disuse will on this view have more or less perfectly obliterated its eyes, and natural selection will often have effected other changes, such as an increase in the length of the antennae or palpi, as a compensation for blindness. Notwithstanding such modifications, we might expect still to see in the cave-animals of America, affinities to the other inhabitants of that continent, and in those of Europe to the inhabitants of the European continent. And this is the case with some of the American cave-animals, as I hear from Professor Dana; and some of the European cave-insects are very closely allied to those of the surrounding country. It would be difficult to give any rational explanation of the affinities of the blind cave-animals to the other inhabitants of the two continents on the ordinary view of their independent creation. That several of the inhabitants of the caves of the Old and New Worlds should be closely related, we might expect from the well-known relationship of most of their other productions. As a blind species of Bathyscia is found in abundance on shady rocks far from caves, the loss of vision in the cave species of this one genus has probably had no relation to its dark habitation; for it is natural that an insect already deprived of vision should readily become adapted to dark caverns. Another blind genus (Anophthalmus) offers this remarkable peculiarity, that the species, as Mr. Murray observes, have not as yet been found anywhere except in caves; yet those which inhabit the several caves of Europe and America are distinct; but it is possible that the progenitors of these several species, while they were furnished with eyes, may formerly have ranged over both continents, and then have become extinct, excepting in their present secluded abodes. Far from feeling surprise that some of the cave-animals should be very anomalous, as Agassiz has remarked in regard to the blind fish, the Amblyopsis, and as is the case with the blind Proteus, with reference to the reptiles of Europe, I am only surprised that more wrecks of ancient life have not been preserved, owing to the less severe competition to which the scanty inhabitants of these dark abodes will have been exposed. ACCLIMATISATION. Habit is hereditary with plants, as in the period of flowering, in the time of sleep, in the amount of rain requisite for seeds to germinate, etc., and this leads me to say a few words on acclimatisation. As it is extremely common for distinct species belonging to the same genus to inhabit hot and cold countries, if it be true that all the species of the same genus are descended from a single parent-form, acclimatisation must be readily effected during a long course of descent. It is notorious that each species is adapted to the climate of its own home: species from an arctic or even from a temperate region cannot endure a tropical climate, or conversely. So again, many succulent plants cannot endure a damp climate. But the degree of adaptation of species to the climates under which they live is often overrated. We may infer this from our frequent inability to predict whether or not an imported plant will endure our climate, and from the number of plants and animals brought from different countries which are here perfectly healthy. We have reason to believe that species in a state of nature are closely limited in their ranges by the competition of other organic beings quite as much as, or more than, by adaptation to particular climates. But whether or not this adaptation is in most cases very close, we have evidence with some few plants, of their becoming, to a certain extent, naturally habituated to different temperatures; that is, they become acclimatised: thus the pines and rhododendrons, raised from seed collected by Dr. Hooker from the same species growing at different heights on the Himalayas, were found to possess in this country different constitutional powers of resisting cold. Mr. Thwaites informs me that he has observed similar facts in Ceylon; analogous observations have been made by Mr. H.C. Watson on European species of plants brought from the Azores to England; and I could give other cases. In regard to animals, several authentic instances could be adduced of species having largely extended, within historical times, their range from warmer to colder latitudes, and conversely; but we do not positively know that these animals were strictly adapted to their native climate, though in all ordinary cases we assume such to be the case; nor do we know that they have subsequently become specially acclimatised to their new homes, so as to be better fitted for them than they were at first. As we may infer that our domestic animals were originally chosen by uncivilised man because they were useful, and because they bred readily under confinement, and not because they were subsequently found capable of far-extended transportation, the common and extraordinary capacity in our domestic animals of not only withstanding the most different climates, but of being perfectly fertile (a far severer test) under them, may be used as an argument that a large proportion of other animals now in a state of nature could easily be brought to bear widely different climates. We must not, however, push the foregoing argument too far, on account of the probable origin of some of our domestic animals from several wild stocks: the blood, for instance, of a tropical and arctic wolf may perhaps be mingled in our domestic breeds. The rat and mouse cannot be considered as domestic animals, but they have been transported by man to many parts of the world, and now have a far wider range than any other rodent; for they live under the cold climate of Faroe in the north and of the Falklands in the south, and on many an island in the torrid zones. Hence adaptation to any special climate may be looked at as a quality readily grafted on an innate wide flexibility of constitution, common to most animals. On this view, the capacity of enduring the most different climates by man himself and by his domestic animals, and the fact of the extinct elephant and rhinoceros having formerly endured a glacial climate, whereas the living species are now all tropical or sub-tropical in their habits, ought not to be looked at as anomalies, but as examples of a very common flexibility of constitution, brought, under peculiar circumstances, into action. How much of the acclimatisation of species to any peculiar climate is due to mere habit, and how much to the natural selection of varieties having different innate constitutions, and how much to both means combined, is an obscure question. That habit or custom has some influence, I must believe, both from analogy and from the incessant advice given in agricultural works, even in the ancient Encyclopaedias of China, to be very cautious in transporting animals from one district to another. And as it is not likely that man should have succeeded in selecting so many breeds and sub-breeds with constitutions specially fitted for their own districts, the result must, I think, be due to habit. On the other hand, natural selection would inevitably tend to preserve those individuals which were born with constitutions best adapted to any country which they inhabited. In treatises on many kinds of cultivated plants, certain varieties are said to withstand certain climates better than others; this is strikingly shown in works on fruit-trees published in the United States, in which certain varieties are habitually recommended for the northern and others for the southern states; and as most of these varieties are of recent origin, they cannot owe their constitutional differences to habit. The case of the Jerusalem artichoke, which is never propagated in England by seed, and of which, consequently, new varieties have not been produced, has even been advanced, as proving that acclimatisation cannot be effected, for it is now as tender as ever it was! The case, also, of the kidney-bean has been often cited for a similar purpose, and with much greater weight; but until some one will sow, during a score of generations, his kidney-beans so early that a very large proportion are destroyed by frost, and then collect seed from the few survivors, with care to prevent accidental crosses, and then again get seed from these seedlings, with the same precautions, the experiment cannot be said to have been even tried. Nor let it be supposed that differences in the constitution of seedling kidney-beans never appear, for an account has been published how much more hardy some seedlings are than others; and of this fact I have myself observed striking instances. On the whole, we may conclude that habit, or use and disuse, have, in some cases, played a considerable part in the modification of the constitution and structure; but that the effects have often been largely combined with, and sometimes overmastered by, the natural selection of innate variations. CORRELATED VARIATION. I mean by this expression that the whole organisation is so tied together, during its growth and development, that when slight variations in any one part occur and are accumulated through natural selection, other parts become modified. This is a very important subject, most imperfectly understood, and no doubt wholly different classes of facts may be here easily confounded together. We shall presently see that simple inheritance often gives the false appearance of correlation. One of the most obvious real cases is, that variations of structure arising in the young or larvae naturally tend to affect the structure of the mature animal. The several parts which are homologous, and which, at an early embryonic period, are identical in structure, and which are necessarily exposed to similar conditions, seem eminently liable to vary in a like manner: we see this in the right and left sides of the body varying in the same manner; in the front and hind legs, and even in the jaws and limbs, varying together, for the lower jaw is believed by some anatomists to be homologous with the limbs. These tendencies, I do not doubt, may be mastered more or less completely by natural selection: thus a family of stags once existed with an antler only on one side; and if this had been of any great use to the breed, it might probably have been rendered permanent by natural selection. Homologous parts, as has been remarked by some authors, tend to cohere; this is often seen in monstrous plants: and nothing is more common than the union of homologous parts in normal structures, as in the union of the petals into a tube. Hard parts seem to affect the form of adjoining soft parts; it is believed by some authors that with birds the diversity in the shape of the pelvis causes the remarkable diversity in the shape of the kidneys. Others believe that the shape of the pelvis in the human mother influences by pressure the shape of the head of the child. In snakes, according to Schlegel, the shape of the body and the manner of swallowing determine the position and form of several of the most important viscera. The nature of the bond is frequently quite obscure. M. Is. Geoffroy St. Hilaire has forcibly remarked that certain malconformations frequently, and that others rarely, coexist without our being able to assign any reason. What can be more singular than the relation in cats between complete whiteness and blue eyes with deafness, or between the tortoise-shell colour and the female sex; or in pigeons, between their feathered feet and skin betwixt the outer toes, or between the presence of more or less down on the young pigeon when first hatched, with the future colour of its plumage; or, again, the relation between the hair and the teeth in the naked Turkish dog, though here no doubt homology comes into play? With respect to this latter case of correlation, I think it can hardly be accidental that the two orders of mammals which are most abnormal in their dermal covering, viz., Cetacea (whales) and Edentata (armadilloes, scaly ant-eaters, etc.), are likewise on the whole the most abnormal in their teeth, but there are so many exceptions to this rule, as Mr. Mivart has remarked, that it has little value. I know of no case better adapted to show the importance of the laws of correlation and variation, independently of utility, and therefore of natural selection, than that of the difference between the outer and inner flowers in some Compositous and Umbelliferous plants. Everyone is familiar with the difference between the ray and central florets of, for instance, the daisy, and this difference is often accompanied with the partial or complete abortion of the reproductive organs. But in some of these plants the seeds also differ in shape and sculpture. These differences have sometimes been attributed to the pressure of the involucra on the florets, or to their mutual pressure, and the shape of the seeds in the ray-florets of some Compositae countenances this idea; but with the Umbelliferae it is by no means, as Dr. Hooker informs me, the species with the densest heads which most frequently differ in their inner and outer flowers. It might have been thought that the development of the ray-petals, by drawing nourishment from the reproductive organs causes their abortion; but this can hardly be the sole case, for in some Compositae the seeds of the outer and inner florets differ, without any difference in the corolla. Possibly these several differences may be connected with the different flow of nutriment towards the central and external flowers. We know, at least, that with irregular flowers those nearest to the axis are most subject to peloria, that is to become abnormally symmetrical. I may add, as an instance of this fact, and as a striking case of correlation, that in many pelargoniums the two upper petals in the central flower of the truss often lose their patches of darker colour; and when this occurs, the adherent nectary is quite aborted, the central flower thus becoming peloric or regular. When the colour is absent from only one of the two upper petals, the nectary is not quite aborted but is much shortened. With respect to the development of the corolla, Sprengel's idea that the ray-florets serve to attract insects, whose agency is highly advantageous, or necessary for the fertilisation of these plants, is highly probable; and if so, natural selection may have come into play. But with respect to the seeds, it seems impossible that their differences in shape, which are not always correlated with any difference in the corolla, can be in any way beneficial; yet in the Umbelliferae these differences are of such apparent importance--the seeds being sometimes orthospermous in the exterior flowers and coelospermous in the central flowers--that the elder De Candolle founded his main divisions in the order on such characters. Hence modifications of structure, viewed by systematists as of high value, may be wholly due to the laws of variation and correlation, without being, as far as we can judge, of the slightest service to the species. We may often falsely attribute to correlated variation structures which are common to whole groups of species, and which in truth are simply due to inheritance; for an ancient progenitor may have acquired through natural selection some one modification in structure, and, after thousands of generations, some other and independent modification; and these two modifications, having been transmitted to a whole group of descendants with diverse habits, would naturally be thought to be in some necessary manner correlated. Some other correlations are apparently due to the manner in which natural selection can alone act. For instance, Alph. De Candolle has remarked that winged seeds are never found in fruits which do not open; I should explain this rule by the impossibility of seeds gradually becoming winged through natural selection, unless the capsules were open; for in this case alone could the seeds, which were a little better adapted to be wafted by the wind, gain an advantage over others less well fitted for wide dispersal. COMPENSATION AND ECONOMY OF GROWTH. The elder Geoffroy and Goethe propounded, at about the same time, their law of compensation or balancement of growth; or, as Goethe expressed it, "in order to spend on one side, nature is forced to economise on the other side." I think this holds true to a certain extent with our domestic productions: if nourishment flows to one part or organ in excess, it rarely flows, at least in excess, to another part; thus it is difficult to get a cow to give much milk and to fatten readily. The same varieties of the cabbage do not yield abundant and nutritious foliage and a copious supply of oil-bearing seeds. When the seeds in our fruits become atrophied, the fruit itself gains largely in size and quality. In our poultry, a large tuft of feathers on the head is generally accompanied by a diminished comb, and a large beard by diminished wattles. With species in a state of nature it can hardly be maintained that the law is of universal application; but many good observers, more especially botanists, believe in its truth. I will not, however, here give any instances, for I see hardly any way of distinguishing between the effects, on the one hand, of a part being largely developed through natural selection and another and adjoining part being reduced by the same process or by disuse, and, on the other hand, the actual withdrawal of nutriment from one part owing to the excess of growth in another and adjoining part. I suspect, also, that some of the cases of compensation which have been advanced, and likewise some other facts, may be merged under a more general principle, namely, that natural selection is continually trying to economise in every part of the organisation. If under changed conditions of life a structure, before useful, becomes less useful, its diminution will be favoured, for it will profit the individual not to have its nutriment wasted in building up a useless structure. I can thus only understand a fact with which I was much struck when examining cirripedes, and of which many other instances could be given: namely, that when a cirripede is parasitic within another cirripede and is thus protected, it loses more or less completely its own shell or carapace. This is the case with the male Ibla, and in a truly extraordinary manner with the Proteolepas: for the carapace in all other cirripedes consists of the three highly important anterior segments of the head enormously developed, and furnished with great nerves and muscles; but in the parasitic and protected Proteolepas, the whole anterior part of the head is reduced to the merest rudiment attached to the bases of the prehensile antennae. Now the saving of a large and complex structure, when rendered superfluous, would be a decided advantage to each successive individual of the species; for in the struggle for life to which every animal is exposed, each would have a better chance of supporting itself, by less nutriment being wasted. Thus, as I believe, natural selection will tend in the long run to reduce any part of the organisation, as soon as it becomes, through changed habits, superfluous, without by any means causing some other part to be largely developed in a corresponding degree. And conversely, that natural selection may perfectly well succeed in largely developing an organ without requiring as a necessary compensation the reduction of some adjoining part. MULTIPLE, RUDIMENTARY, AND LOWLY-ORGANISED STRUCTURES ARE VARIABLE. It seems to be a rule, as remarked by Is. Geoffroy St. Hilaire, both with varieties and species, that when any part or organ is repeated many times in the same individual (as the vertebrae in snakes, and the stamens in polyandrous flowers) the number is variable; whereas the number of the same part or organ, when it occurs in lesser numbers, is constant. The same author as well as some botanists, have further remarked that multiple parts are extremely liable to vary in structure. As "vegetative repetition," to use Professor Owen's expression, is a sign of low organisation; the foregoing statements accord with the common opinion of naturalists, that beings which stand low in the scale of nature are more variable than those which are higher. I presume that lowness here means that the several parts of the organisation have been but little specialised for particular functions; and as long as the same part has to perform diversified work, we can perhaps see why it should remain variable, that is, why natural selection should not have preserved or rejected each little deviation of form so carefully as when the part has to serve for some one special purpose. In the same way that a knife which has to cut all sorts of things may be of almost any shape; whilst a tool for some particular purpose must be of some particular shape. Natural selection, it should never be forgotten, can act solely through and for the advantage of each being. Rudimentary parts, as is generally admitted, are apt to be highly variable. We shall have to recur to this subject; and I will here only add that their variability seems to result from their uselessness, and consequently from natural selection having had no power to check deviations in their structure. A PART DEVELOPED IN ANY SPECIES IN AN EXTRAORDINARY DEGREE OR MANNER, IN COMPARISON WITH THE SAME PART IN ALLIED SPECIES, TENDS TO BE HIGHLY VARIABLE. Several years ago I was much struck by a remark to the above effect made by Mr. Waterhouse. Professor Owen, also, seems to have come to a nearly similar conclusion. It is hopeless to attempt to convince any one of the truth of the above proposition without giving the long array of facts which I have collected, and which cannot possibly be here introduced. I can only state my conviction that it is a rule of high generality. I am aware of several causes of error, but I hope that I have made due allowances for them. It should be understood that the rule by no means applies to any part, however unusually developed, unless it be unusually developed in one species or in a few species in comparison with the same part in many closely allied species. Thus, the wing of the bat is a most abnormal structure in the class of mammals; but the rule would not apply here, because the whole group of bats possesses wings; it would apply only if some one species had wings developed in a remarkable manner in comparison with the other species of the same genus. The rule applies very strongly in the case of secondary sexual characters, when displayed in any unusual manner. The term, secondary sexual characters, used by Hunter, relates to characters which are attached to one sex, but are not directly connected with the act of reproduction. The rule applies to males and females; but more rarely to females, as they seldom offer remarkable secondary sexual characters. The rule being so plainly applicable in the case of secondary sexual characters, may be due to the great variability of these characters, whether or not displayed in any unusual manner--of which fact I think there can be little doubt. But that our rule is not confined to secondary sexual characters is clearly shown in the case of hermaphrodite cirripedes; I particularly attended to Mr. Waterhouse's remark, whilst investigating this order, and I am fully convinced that the rule almost always holds good. I shall, in a future work, give a list of all the more remarkable cases. I will here give only one, as it illustrates the rule in its largest application. The opercular valves of sessile cirripedes (rock barnacles) are, in every sense of the word, very important structures, and they differ extremely little even in distinct genera; but in the several species of one genus, Pyrgoma, these valves present a marvellous amount of diversification; the homologous valves in the different species being sometimes wholly unlike in shape; and the amount of variation in the individuals of the same species is so great that it is no exaggeration to state that the varieties of the same species differ more from each other in the characters derived from these important organs, than do the species belonging to other distinct genera. As with birds the individuals of the same species, inhabiting the same country, vary extremely little, I have particularly attended to them; and the rule certainly seems to hold good in this class. I cannot make out that it applies to plants, and this would have seriously shaken my belief in its truth, had not the great variability in plants made it particularly difficult to compare their relative degrees of variability. When we see any part or organ developed in a remarkable degree or manner in a species, the fair presumption is that it is of high importance to that species: nevertheless it is in this case eminently liable to variation. Why should this be so? On the view that each species has been independently created, with all its parts as we now see them, I can see no explanation. But on the view that groups of species are descended from some other species, and have been modified through natural selection, I think we can obtain some light. First let me make some preliminary remarks. If, in our domestic animals, any part or the whole animal be neglected, and no selection be applied, that part (for instance, the comb in the Dorking fowl) or the whole breed will cease to have a uniform character: and the breed may be said to be degenerating. In rudimentary organs, and in those which have been but little specialised for any particular purpose, and perhaps in polymorphic groups, we see a nearly parallel case; for in such cases natural selection either has not or cannot come into full play, and thus the organisation is left in a fluctuating condition. But what here more particularly concerns us is, that those points in our domestic animals, which at the present time are undergoing rapid change by continued selection, are also eminently liable to variation. Look at the individuals of the same breed of the pigeon; and see what a prodigious amount of difference there is in the beak of tumblers, in the beak and wattle of carriers, in the carriage and tail of fantails, etc., these being the points now mainly attended to by English fanciers. Even in the same sub-breed, as in that of the short-faced tumbler, it is notoriously difficult to breed nearly perfect birds, many departing widely from the standard. There may truly be said to be a constant struggle going on between, on the one hand, the tendency to reversion to a less perfect state, as well as an innate tendency to new variations, and, on the other hand, the power of steady selection to keep the breed true. In the long run selection gains the day, and we do not expect to fail so completely as to breed a bird as coarse as a common tumbler pigeon from a good short-faced strain. But as long as selection is rapidly going on, much variability in the parts undergoing modification may always be expected. Now let us turn to nature. When a part has been developed in an extraordinary manner in any one species, compared with the other species of the same genus, we may conclude that this part has undergone an extraordinary amount of modification since the period when the several species branched off from the common progenitor of the genus. This period will seldom be remote in any extreme degree, as species rarely endure for more than one geological period. An extraordinary amount of modification implies an unusually large and long-continued amount of variability, which has continually been accumulated by natural selection for the benefit of the species. But as the variability of the extraordinarily developed part or organ has been so great and long-continued within a period not excessively remote, we might, as a general rule, still expect to find more variability in such parts than in other parts of the organisation which have remained for a much longer period nearly constant. And this, I am convinced, is the case. That the struggle between natural selection on the one hand, and the tendency to reversion and variability on the other hand, will in the course of time cease; and that the most abnormally developed organs may be made constant, I see no reason to doubt. Hence, when an organ, however abnormal it may be, has been transmitted in approximately the same condition to many modified descendants, as in the case of the wing of the bat, it must have existed, according to our theory, for an immense period in nearly the same state; and thus it has come not to be more variable than any other structure. It is only in those cases in which the modification has been comparatively recent and extraordinarily great that we ought to find the GENERATIVE VARIABILITY, as it may be called, still present in a high degree. For in this case the variability will seldom as yet have been fixed by the continued selection of the individuals varying in the required manner and degree, and by the continued rejection of those tending to revert to a former and less modified condition. SPECIFIC CHARACTERS MORE VARIABLE THAN GENERIC CHARACTERS. The principle discussed under the last heading may be applied to our present subject. It is notorious that specific characters are more variable than generic. To explain by a simple example what is meant: if in a large genus of plants some species had blue flowers and some had red, the colour would be only a specific character, and no one would be surprised at one of the blue species varying into red, or conversely; but if all the species had blue flowers, the colour would become a generic character, and its variation would be a more unusual circumstance. I have chosen this example because the explanation which most naturalists would advance is not here applicable, namely, that specific characters are more variable than generic, because they are taken from parts of less physiological importance than those commonly used for classing genera. I believe this explanation is partly, yet only indirectly, true; I shall, however, have to return to this point in the chapter on Classification. It would be almost superfluous to adduce evidence in support of the statement, that ordinary specific characters are more variable than generic; but with respect to important characters, I have repeatedly noticed in works on natural history, that when an author remarks with surprise that some important organ or part, which is generally very constant throughout a large group of species, DIFFERS considerably in closely-allied species, it is often VARIABLE in the individuals of the same species. And this fact shows that a character, which is generally of generic value, when it sinks in value and becomes only of specific value, often becomes variable, though its physiological importance may remain the same. Something of the same kind applies to monstrosities: at least Is. Geoffroy St. Hilaire apparently entertains no doubt, that the more an organ normally differs in the different species of the same group, the more subject it is to anomalies in the individuals. On the ordinary view of each species having been independently created, why should that part of the structure, which differs from the same part in other independently created species of the same genus, be more variable than those parts which are closely alike in the several species? I do not see that any explanation can be given. But on the view that species are only strongly marked and fixed varieties, we might expect often to find them still continuing to vary in those parts of their structure which have varied within a moderately recent period, and which have thus come to differ. Or to state the case in another manner: the points in which all the species of a genus resemble each other, and in which they differ from allied genera, are called generic characters; and these characters may be attributed to inheritance from a common progenitor, for it can rarely have happened that natural selection will have modified several distinct species, fitted to more or less widely different habits, in exactly the same manner: and as these so-called generic characters have been inherited from before the period when the several species first branched off from their common progenitor, and subsequently have not varied or come to differ in any degree, or only in a slight degree, it is not probable that they should vary at the present day. On the other hand, the points in which species differ from other species of the same genus are called specific characters; and as these specific characters have varied and come to differ since the period when the species branched off from a common progenitor, it is probable that they should still often be in some degree variable--at least more variable than those parts of the organisation which have for a very long period remained constant. SECONDARY SEXUAL CHARACTERS VARIABLE. I think it will be admitted by naturalists, without my entering on details, that secondary sexual characters are highly variable. It will also be admitted that species of the same group differ from each other more widely in their secondary sexual characters, than in other parts of their organisation; compare, for instance, the amount of difference between the males of gallinaceous birds, in which secondary sexual characters are strongly displayed, with the amount of difference between the females. The cause of the original variability of these characters is not manifest; but we can see why they should not have been rendered as constant and uniform as others, for they are accumulated by sexual selection, which is less rigid in its action than ordinary selection, as it does not entail death, but only gives fewer offspring to the less favoured males. Whatever the cause may be of the variability of secondary sexual characters, as they are highly variable, sexual selection will have had a wide scope for action, and may thus have succeeded in giving to the species of the same group a greater amount of difference in these than in other respects. It is a remarkable fact, that the secondary differences between the two sexes of the same species are generally displayed in the very same parts of the organisation in which the species of the same genus differ from each other. Of this fact I will give in illustration the first two instances which happen to stand on my list; and as the differences in these cases are of a very unusual nature, the relation can hardly be accidental. The same number of joints in the tarsi is a character common to very large groups of beetles, but in the Engidae, as Westwood has remarked, the number varies greatly and the number likewise differs in the two sexes of the same species. Again in the fossorial hymenoptera, the neuration of the wings is a character of the highest importance, because common to large groups; but in certain genera the neuration differs in the different species, and likewise in the two sexes of the same species. Sir J. Lubbock has recently remarked, that several minute crustaceans offer excellent illustrations of this law. "In Pontella, for instance, the sexual characters are afforded mainly by the anterior antennae and by the fifth pair of legs: the specific differences also are principally given by these organs." This relation has a clear meaning on my view: I look at all the species of the same genus as having as certainly descended from the same progenitor, as have the two sexes of any one species. Consequently, whatever part of the structure of the common progenitor, or of its early descendants, became variable; variations of this part would, it is highly probable, be taken advantage of by natural and sexual selection, in order to fit the several places in the economy of nature, and likewise to fit the two sexes of the same species to each other, or to fit the males to struggle with other males for the possession of the females. Finally, then, I conclude that the greater variability of specific characters, or those which distinguish species from species, than of generic characters, or those which are possessed by all the species; that the frequent extreme variability of any part which is developed in a species in an extraordinary manner in comparison with the same part in its congeners; and the slight degree of variability in a part, however extraordinarily it may be developed, if it be common to a whole group of species; that the great variability of secondary sexual characters and their great difference in closely allied species; that secondary sexual and ordinary specific differences are generally displayed in the same parts of the organisation, are all principles closely connected together. All being mainly due to the species of the same group being the descendants of a common progenitor, from whom they have inherited much in common, to parts which have recently and largely varied being more likely still to go on varying than parts which have long been inherited and have not varied, to natural selection having more or less completely, according to the lapse of time, overmastered the tendency to reversion and to further variability, to sexual selection being less rigid than ordinary selection, and to variations in the same parts having been accumulated by natural and sexual selection, and thus having been adapted for secondary sexual, and for ordinary purposes. DISTINCT SPECIES PRESENT ANALOGOUS VARIATIONS, SO THAT A VARIETY OF ONE SPECIES OFTEN ASSUMES A CHARACTER PROPER TO AN ALLIED SPECIES, OR REVERTS TO SOME OF THE CHARACTERS OF AN EARLY PROGENITOR. These propositions will be most readily understood by looking to our domestic races. The most distinct breeds of the pigeon, in countries widely apart, present sub-varieties with reversed feathers on the head, and with feathers on the feet, characters not possessed by the aboriginal rock-pigeon; these then are analogous variations in two or more distinct races. The frequent presence of fourteen or even sixteen tail-feathers in the pouter may be considered as a variation representing the normal structure of another race, the fantail. I presume that no one will doubt that all such analogous variations are due to the several races of the pigeon having inherited from a common parent the same constitution and tendency to variation, when acted on by similar unknown influences. In the vegetable kingdom we have a case of analogous variation, in the enlarged stems, or as commonly called roots, of the Swedish turnip and ruta-baga, plants which several botanists rank as varieties produced by cultivation from a common parent: if this be not so, the case will then be one of analogous variation in two so-called distinct species; and to these a third may be added, namely, the common turnip. According to the ordinary view of each species having been independently created, we should have to attribute this similarity in the enlarged stems of these three plants, not to the vera causa of community of descent, and a consequent tendency to vary in a like manner, but to three separate yet closely related acts of creation. Many similar cases of analogous variation have been observed by Naudin in the great gourd family, and by various authors in our cereals. Similar cases occurring with insects under natural conditions have lately been discussed with much ability by Mr. Walsh, who has grouped them under his law of equable variability. With pigeons, however, we have another case, namely, the occasional appearance in all the breeds, of slaty-blue birds with two black bars on the wings, white loins, a bar at the end of the tail, with the outer feathers externally edged near their bases with white. As all these marks are characteristic of the parent rock-pigeon, I presume that no one will doubt that this is a case of reversion, and not of a new yet analogous variation appearing in the several breeds. We may, I think, confidently come to this conclusion, because, as we have seen, these coloured marks are eminently liable to appear in the crossed offspring of two distinct and differently coloured breeds; and in this case there is nothing in the external conditions of life to cause the reappearance of the slaty-blue, with the several marks, beyond the influence of the mere act of crossing on the laws of inheritance. No doubt it is a very surprising fact that characters should reappear after having been lost for many, probably for hundreds of generations. But when a breed has been crossed only once by some other breed, the offspring occasionally show for many generations a tendency to revert in character to the foreign breed--some say, for a dozen or even a score of generations. After twelve generations, the proportion of blood, to use a common expression, from one ancestor, is only 1 in 2048; and yet, as we see, it is generally believed that a tendency to reversion is retained by this remnant of foreign blood. In a breed which has not been crossed, but in which BOTH parents have lost some character which their progenitor possessed, the tendency, whether strong or weak, to reproduce the lost character might, as was formerly remarked, for all that we can see to the contrary, be transmitted for almost any number of generations. When a character which has been lost in a breed, reappears after a great number of generations, the most probable hypothesis is, not that one individual suddenly takes after an ancestor removed by some hundred generations, but that in each successive generation the character in question has been lying latent, and at last, under unknown favourable conditions, is developed. With the barb-pigeon, for instance, which very rarely produces a blue bird, it is probable that there is a latent tendency in each generation to produce blue plumage. The abstract improbability of such a tendency being transmitted through a vast number of generations, is not greater than that of quite useless or rudimentary organs being similarly transmitted. A mere tendency to produce a rudiment is indeed sometimes thus inherited. As all the species of the same genus are supposed to be descended from a common progenitor, it might be expected that they would occasionally vary in an analogous manner; so that the varieties of two or more species would resemble each other, or that a variety of one species would resemble in certain characters another and distinct species, this other species being, according to our view, only a well-marked and permanent variety. But characters exclusively due to analogous variation would probably be of an unimportant nature, for the preservation of all functionally important characters will have been determined through natural selection, in accordance with the different habits of the species. It might further be expected that the species of the same genus would occasionally exhibit reversions to long-lost characters. As, however, we do not know the common ancestor of any natural group, we cannot distinguish between reversionary and analogous characters. If, for instance, we did not know that the parent rock-pigeon was not feather-footed or turn-crowned, we could not have told, whether such characters in our domestic breeds were reversions or only analogous variations; but we might have inferred that the blue colour was a case of reversion from the number of the markings, which are correlated with this tint, and which would not probably have all appeared together from simple variation. More especially we might have inferred this from the blue colour and the several marks so often appearing when differently coloured breeds are crossed. Hence, although under nature it must generally be left doubtful, what cases are reversions to formerly existing characters, and what are new but analogous variations, yet we ought, on our theory, sometimes to find the varying offspring of a species assuming characters which are already present in other members of the same group. And this undoubtedly is the case. The difficulty in distinguishing variable species is largely due to the varieties mocking, as it were, other species of the same genus. A considerable catalogue, also, could be given of forms intermediate between two other forms, which themselves can only doubtfully be ranked as species; and this shows, unless all these closely allied forms be considered as independently created species, that they have in varying assumed some of the characters of the others. But the best evidence of analogous variations is afforded by parts or organs which are generally constant in character, but which occasionally vary so as to resemble, in some degree, the same part or organ in an allied species. I have collected a long list of such cases; but here, as before, I lie under the great disadvantage of not being able to give them. I can only repeat that such cases certainly occur, and seem to me very remarkable. I will, however, give one curious and complex case, not indeed as affecting any important character, but from occurring in several species of the same genus, partly under domestication and partly under nature. It is a case almost certainly of reversion. The ass sometimes has very distinct transverse bars on its legs, like those on the legs of a zebra. It has been asserted that these are plainest in the foal, and from inquiries which I have made, I believe this to be true. The stripe on the shoulder is sometimes double, and is very variable in length and outline. A white ass, but NOT an albino, has been described without either spinal or shoulder stripe; and these stripes are sometimes very obscure, or actually quite lost, in dark-coloured asses. The koulan of Pallas is said to have been seen with a double shoulder-stripe. Mr. Blyth has seen a specimen of the hemionus with a distinct shoulder-stripe, though it properly has none; and I have been informed by Colonel Poole that foals of this species are generally striped on the legs and faintly on the shoulder. The quagga, though so plainly barred like a zebra over the body, is without bars on the legs; but Dr. Gray has figured one specimen with very distinct zebra-like bars on the hocks. With respect to the horse, I have collected cases in England of the spinal stripe in horses of the most distinct breeds, and of ALL colours; transverse bars on the legs are not rare in duns, mouse-duns, and in one instance in a chestnut; a faint shoulder-stripe may sometimes be seen in duns, and I have seen a trace in a bay horse. My son made a careful examination and sketch for me of a dun Belgian cart-horse with a double stripe on each shoulder and with leg-stripes. I have myself seen a dun Devonshire pony, and a small dun Welsh pony has been carefully described to me, both with THREE parallel stripes on each shoulder. In the northwest part of India the Kattywar breed of horses is so generally striped, that, as I hear from Colonel Poole, who examined this breed for the Indian Government, a horse without stripes is not considered as purely bred. The spine is always striped; the legs are generally barred; and the shoulder-stripe, which is sometimes double and sometimes treble, is common; the side of the face, moreover, is sometimes striped. The stripes are often plainest in the foal; and sometimes quite disappear in old horses. Colonel Poole has seen both gray and bay Kattywar horses striped when first foaled. I have also reason to suspect, from information given me by Mr. W.W. Edwards, that with the English race-horse the spinal stripe is much commoner in the foal than in the full-grown animal. I have myself recently bred a foal from a bay mare (offspring of a Turkoman horse and a Flemish mare) by a bay English race-horse. This foal, when a week old, was marked on its hinder quarters and on its forehead with numerous very narrow, dark, zebra-like bars, and its legs were feebly striped. All the stripes soon disappeared completely. Without here entering on further details I may state that I have collected cases of leg and shoulder stripes in horses of very different breeds in various countries from Britain to Eastern China; and from Norway in the north to the Malay Archipelago in the south. In all parts of the world these stripes occur far oftenest in duns and mouse-duns; by the term dun a large range of colour is included, from one between brown and black to a close approach to cream colour. I am aware that Colonel Hamilton Smith, who has written on this subject, believes that the several breeds of the horse are descended from several aboriginal species, one of which, the dun, was striped; and that the above-described appearances are all due to ancient crosses with the dun stock. But this view may be safely rejected, for it is highly improbable that the heavy Belgian cart-horse, Welsh ponies, Norwegian cobs, the lanky Kattywar race, etc., inhabiting the most distant parts of the world, should have all have been crossed with one supposed aboriginal stock. Now let us turn to the effects of crossing the several species of the horse genus. Rollin asserts that the common mule from the ass and horse is particularly apt to have bars on its legs; according to Mr. Gosse, in certain parts of the United States, about nine out of ten mules have striped legs. I once saw a mule with its legs so much striped that any one might have thought that it was a hybrid zebra; and Mr. W.C. Martin, in his excellent treatise on the horse, has given a figure of a similar mule. In four coloured drawings, which I have seen, of hybrids between the ass and zebra, the legs were much more plainly barred than the rest of the body; and in one of them there was a double shoulder-stripe. In Lord Morton's famous hybrid, from a chestnut mare and male quagga, the hybrid and even the pure offspring subsequently produced from the same mare by a black Arabian sire, were much more plainly barred across the legs than is even the pure quagga. Lastly, and this is another most remarkable case, a hybrid has been figured by Dr. Gray (and he informs me that he knows of a second case) from the ass and the hemionus; and this hybrid, though the ass only occasionally has stripes on his legs and the hemionus has none and has not even a shoulder-stripe, nevertheless had all four legs barred, and had three short shoulder-stripes, like those on the dun Devonshire and Welsh ponies, and even had some zebra-like stripes on the sides of its face. With respect to this last fact, I was so convinced that not even a stripe of colour appears from what is commonly called chance, that I was led solely from the occurrence of the face-stripes on this hybrid from the ass and hemionus to ask Colonel Poole whether such face-stripes ever occurred in the eminently striped Kattywar breed of horses, and was, as we have seen, answered in the affirmative. What now are we to say to these several facts? We see several distinct species of the horse genus becoming, by simple variation, striped on the legs like a zebra, or striped on the shoulders like an ass. In the horse we see this tendency strong whenever a dun tint appears--a tint which approaches to that of the general colouring of the other species of the genus. The appearance of the stripes is not accompanied by any change of form, or by any other new character. We see this tendency to become striped most strongly displayed in hybrids from between several of the most distinct species. Now observe the case of the several breeds of pigeons: they are descended from a pigeon (including two or three sub-species or geographical races) of a bluish colour, with certain bars and other marks; and when any breed assumes by simple variation a bluish tint, these bars and other marks invariably reappear; but without any other change of form or character. When the oldest and truest breeds of various colours are crossed, we see a strong tendency for the blue tint and bars and marks to reappear in the mongrels. I have stated that the most probable hypothesis to account for the reappearance of very ancient characters, is--that there is a TENDENCY in the young of each successive generation to produce the long-lost character, and that this tendency, from unknown causes, sometimes prevails. And we have just seen that in several species of the horse genus the stripes are either plainer or appear more commonly in the young than in the old. Call the breeds of pigeons, some of which have bred true for centuries, species; and how exactly parallel is the case with that of the species of the horse genus! For myself, I venture confidently to look back thousands on thousands of generations, and I see an animal striped like a zebra, but perhaps otherwise very differently constructed, the common parent of our domestic horse (whether or not it be descended from one or more wild stocks) of the ass, the hemionus, quagga, and zebra. He who believes that each equine species was independently created, will, I presume, assert that each species has been created with a tendency to vary, both under nature and under domestication, in this particular manner, so as often to become striped like the other species of the genus; and that each has been created with a strong tendency, when crossed with species inhabiting distant quarters of the world, to produce hybrids resembling in their stripes, not their own parents, but other species of the genus. To admit this view is, as it seems to me, to reject a real for an unreal, or at least for an unknown cause. It makes the works of God a mere mockery and deception; I would almost as soon believe with the old and ignorant cosmogonists, that fossil shells had never lived, but had been created in stone so as to mock the shells now living on the sea-shore. SUMMARY. Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part has varied. But whenever we have the means of instituting a comparison, the same laws appear to have acted in producing the lesser differences between varieties of the same species, and the greater differences between species of the same genus. Changed conditions generally induce mere fluctuating variability, but sometimes they cause direct and definite effects; and these may become strongly marked in the course of time, though we have not sufficient evidence on this head. Habit in producing constitutional peculiarities, and use in strengthening, and disuse in weakening and diminishing organs, appear in many cases to have been potent in their effects. Homologous parts tend to vary in the same manner, and homologous parts tend to cohere. Modifications in hard parts and in external parts sometimes affect softer and internal parts. When one part is largely developed, perhaps it tends to draw nourishment from the adjoining parts; and every part of the structure which can be saved without detriment will be saved. Changes of structure at an early age may affect parts subsequently developed; and many cases of correlated variation, the nature of which we are unable to understand, undoubtedly occur. Multiple parts are variable in number and in structure, perhaps arising from such parts not having been closely specialised for any particular function, so that their modifications have not been closely checked by natural selection. It follows probably from this same cause, that organic beings low in the scale are more variable than those standing higher in the scale, and which have their whole organisation more specialised. Rudimentary organs, from being useless, are not regulated by natural selection, and hence are variable. Specific characters--that is, the characters which have come to differ since the several species of the same genus branched off from a common parent--are more variable than generic characters, or those which have long been inherited, and have not differed within this same period. In these remarks we have referred to special parts or organs being still variable, because they have recently varied and thus come to differ; but we have also seen in the second chapter that the same principle applies to the whole individual; for in a district where many species of a genus are found--that is, where there has been much former variation and differentiation, or where the manufactory of new specific forms has been actively at work--in that district and among these species, we now find, on an average, most varieties. Secondary sexual characters are highly variable, and such characters differ much in the species of the same group. Variability in the same parts of the organisation has generally been taken advantage of in giving secondary sexual differences to the two sexes of the same species, and specific differences to the several species of the same genus. Any part or organ developed to an extraordinary size or in an extraordinary manner, in comparison with the same part or organ in the allied species, must have gone through an extraordinary amount of modification since the genus arose; and thus we can understand why it should often still be variable in a much higher degree than other parts; for variation is a long-continued and slow process, and natural selection will in such cases not as yet have had time to overcome the tendency to further variability and to reversion to a less modified state. But when a species with an extraordinarily developed organ has become the parent of many modified descendants--which on our view must be a very slow process, requiring a long lapse of time--in this case, natural selection has succeeded in giving a fixed character to the organ, in however extraordinary a manner it may have been developed. Species inheriting nearly the same constitution from a common parent, and exposed to similar influences, naturally tend to present analogous variations, or these same species may occasionally revert to some of the characters of their ancient progenitors. Although new and important modifications may not arise from reversion and analogous variation, such modifications will add to the beautiful and harmonious diversity of nature. Whatever the cause may be of each slight difference between the offspring and their parents--and a cause for each must exist--we have reason to believe that it is the steady accumulation of beneficial differences which has given rise to all the more important modifications of structure in relation to the habits of each species. CHAPTER VI. DIFFICULTIES OF THE THEORY. Difficulties of the theory of descent with modification--Absence or rarity of transitional varieties--Transitions in habits of life--Diversified habits in the same species--Species with habits widely different from those of their allies--Organs of extreme perfection--Modes of transition--Cases of difficulty--Natura non facit saltum--Organs of small importance--Organs not in all cases absolutely perfect--The law of Unity of Type and of the Conditions of Existence embraced by the theory of Natural Selection. Long before the reader has arrived at this part of my work, a crowd of difficulties will have occurred to him. Some of them are so serious that to this day I can hardly reflect on them without being in some degree staggered; but, to the best of my judgment, the greater number are only apparent, and those that are real are not, I think, fatal to the theory. These difficulties and objections may be classed under the following heads: First, why, if species have descended from other species by fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion, instead of the species being, as we see them, well defined? Secondly, is it possible that an animal having, for instance, the structure and habits of a bat, could have been formed by the modification of some other animal with widely different habits and structure? Can we believe that natural selection could produce, on the one hand, an organ of trifling importance, such as the tail of a giraffe, which serves as a fly-flapper, and, on the other hand, an organ so wonderful as the eye? Thirdly, can instincts be acquired and modified through natural selection? What shall we say to the instinct which leads the bee to make cells, and which has practically anticipated the discoveries of profound mathematicians? Fourthly, how can we account for species, when crossed, being sterile and producing sterile offspring, whereas, when varieties are crossed, their fertility is unimpaired? The two first heads will be here discussed; some miscellaneous objections in the following chapter; Instinct and Hybridism in the two succeeding chapters. ON THE ABSENCE OR RARITY OF TRANSITIONAL VARIETIES. As natural selection acts solely by the preservation of profitable modifications, each new form will tend in a fully-stocked country to take the place of, and finally to exterminate, its own less improved parent-form and other less-favoured forms with which it comes into competition. Thus extinction and natural selection go hand in hand. Hence, if we look at each species as descended from some unknown form, both the parent and all the transitional varieties will generally have been exterminated by the very process of the formation and perfection of the new form. But, as by this theory innumerable transitional forms must have existed, why do we not find them embedded in countless numbers in the crust of the earth? It will be more convenient to discuss this question in the chapter on the imperfection of the geological record; and I will here only state that I believe the answer mainly lies in the record being incomparably less perfect than is generally supposed. The crust of the earth is a vast museum; but the natural collections have been imperfectly made, and only at long intervals of time. But it may be urged that when several closely allied species inhabit the same territory, we surely ought to find at the present time many transitional forms. Let us take a simple case: in travelling from north to south over a continent, we generally meet at successive intervals with closely allied or representative species, evidently filling nearly the same place in the natural economy of the land. These representative species often meet and interlock; and as the one becomes rarer and rarer, the other becomes more and more frequent, till the one replaces the other. But if we compare these species where they intermingle, they are generally as absolutely distinct from each other in every detail of structure as are specimens taken from the metropolis inhabited by each. By my theory these allied species are descended from a common parent; and during the process of modification, each has become adapted to the conditions of life of its own region, and has supplanted and exterminated its original parent-form and all the transitional varieties between its past and present states. Hence we ought not to expect at the present time to meet with numerous transitional varieties in each region, though they must have existed there, and may be embedded there in a fossil condition. But in the intermediate region, having intermediate conditions of life, why do we not now find closely-linking intermediate varieties? This difficulty for a long time quite confounded me. But I think it can be in large part explained. In the first place we should be extremely cautious in inferring, because an area is now continuous, that it has been continuous during a long period. Geology would lead us to believe that most continents have been broken up into islands even during the later tertiary periods; and in such islands distinct species might have been separately formed without the possibility of intermediate varieties existing in the intermediate zones. By changes in the form of the land and of climate, marine areas now continuous must often have existed within recent times in a far less continuous and uniform condition than at present. But I will pass over this way of escaping from the difficulty; for I believe that many perfectly defined species have been formed on strictly continuous areas; though I do not doubt that the formerly broken condition of areas now continuous, has played an important part in the formation of new species, more especially with freely-crossing and wandering animals. In looking at species as they are now distributed over a wide area, we generally find them tolerably numerous over a large territory, then becoming somewhat abruptly rarer and rarer on the confines, and finally disappearing. Hence the neutral territory between two representative species is generally narrow in comparison with the territory proper to each. We see the same fact in ascending mountains, and sometimes it is quite remarkable how abruptly, as Alph. De Candolle has observed, a common alpine species disappears. The same fact has been noticed by E. Forbes in sounding the depths of the sea with the dredge. To those who look at climate and the physical conditions of life as the all-important elements of distribution, these facts ought to cause surprise, as climate and height or depth graduate away insensibly. But when we bear in mind that almost every species, even in its metropolis, would increase immensely in numbers, were it not for other competing species; that nearly all either prey on or serve as prey for others; in short, that each organic being is either directly or indirectly related in the most important manner to other organic beings--we see that the range of the inhabitants of any country by no means exclusively depends on insensibly changing physical conditions, but in large part on the presence of other species, on which it lives, or by which it is destroyed, or with which it comes into competition; and as these species are already defined objects, not blending one into another by insensible gradations, the range of any one species, depending as it does on the range of others, will tend to be sharply defined. Moreover, each species on the confines of its range, where it exists in lessened numbers, will, during fluctuations in the number of its enemies or of its prey, or in the nature of the seasons, be extremely liable to utter extermination; and thus its geographical range will come to be still more sharply defined. As allied or representative species, when inhabiting a continuous area, are generally distributed in such a manner that each has a wide range, with a comparatively narrow neutral territory between them, in which they become rather suddenly rarer and rarer; then, as varieties do not essentially differ from species, the same rule will probably apply to both; and if we take a varying species inhabiting a very large area, we shall have to adapt two varieties to two large areas, and a third variety to a narrow intermediate zone. The intermediate variety, consequently, will exist in lesser numbers from inhabiting a narrow and lesser area; and practically, as far as I can make out, this rule holds good with varieties in a state of nature. I have met with striking instances of the rule in the case of varieties intermediate between well-marked varieties in the genus Balanus. And it would appear from information given me by Mr. Watson, Dr. Asa Gray, and Mr. Wollaston, that generally, when varieties intermediate between two other forms occur, they are much rarer numerically than the forms which they connect. Now, if we may trust these facts and inferences, and conclude that varieties linking two other varieties together generally have existed in lesser numbers than the forms which they connect, then we can understand why intermediate varieties should not endure for very long periods: why, as a general rule, they should be exterminated and disappear, sooner than the forms which they originally linked together. For any form existing in lesser numbers would, as already remarked, run a greater chance of being exterminated than one existing in large numbers; and in this particular case the intermediate form would be eminently liable to the inroads of closely allied forms existing on both sides of it. But it is a far more important consideration, that during the process of further modification, by which two varieties are supposed to be converted and perfected into two distinct species, the two which exist in larger numbers, from inhabiting larger areas, will have a great advantage over the intermediate variety, which exists in smaller numbers in a narrow and intermediate zone. For forms existing in larger numbers will have a better chance, within any given period, of presenting further favourable variations for natural selection to seize on, than will the rarer forms which exist in lesser numbers. Hence, the more common forms, in the race for life, will tend to beat and supplant the less common forms, for these will be more slowly modified and improved. It is the same principle which, as I believe, accounts for the common species in each country, as shown in the second chapter, presenting on an average a greater number of well-marked varieties than do the rarer species. I may illustrate what I mean by supposing three varieties of sheep to be kept, one adapted to an extensive mountainous region; a second to a comparatively narrow, hilly tract; and a third to the wide plains at the base; and that the inhabitants are all trying with equal steadiness and skill to improve their stocks by selection; the chances in this case will be strongly in favour of the great holders on the mountains or on the plains improving their breeds more quickly than the small holders on the intermediate narrow, hilly tract; and consequently the improved mountain or plain breed will soon take the place of the less improved hill breed; and thus the two breeds, which originally existed in greater numbers, will come into close contact with each other, without the interposition of the supplanted, intermediate hill variety. To sum up, I believe that species come to be tolerably well-defined objects, and do not at any one period present an inextricable chaos of varying and intermediate links: first, because new varieties are very slowly formed, for variation is a slow process, and natural selection can do nothing until favourable individual differences or variations occur, and until a place in the natural polity of the country can be better filled by some modification of some one or more of its inhabitants. And such new places will depend on slow changes of climate, or on the occasional immigration of new inhabitants, and, probably, in a still more important degree, on some of the old inhabitants becoming slowly modified, with the new forms thus produced and the old ones acting and reacting on each other. So that, in any one region and at any one time, we ought to see only a few species presenting slight modifications of structure in some degree permanent; and this assuredly we do see. Secondly, areas now continuous must often have existed within the recent period as isolated portions, in which many forms, more especially among the classes which unite for each birth and wander much, may have separately been rendered sufficiently distinct to rank as representative species. In this case, intermediate varieties between the several representative species and their common parent, must formerly have existed within each isolated portion of the land, but these links during the process of natural selection will have been supplanted and exterminated, so that they will no longer be found in a living state. Thirdly, when two or more varieties have been formed in different portions of a strictly continuous area, intermediate varieties will, it is probable, at first have been formed in the intermediate zones, but they will generally have had a short duration. For these intermediate varieties will, from reasons already assigned (namely from what we know of the actual distribution of closely allied or representative species, and likewise of acknowledged varieties), exist in the intermediate zones in lesser numbers than the varieties which they tend to connect. From this cause alone the intermediate varieties will be liable to accidental extermination; and during the process of further modification through natural selection, they will almost certainly be beaten and supplanted by the forms which they connect; for these, from existing in greater numbers will, in the aggregate, present more varieties, and thus be further improved through natural selection and gain further advantages. Lastly, looking not to any one time, but at all time, if my theory be true, numberless intermediate varieties, linking closely together all the species of the same group, must assuredly have existed; but the very process of natural selection constantly tends, as has been so often remarked, to exterminate the parent forms and the intermediate links. Consequently evidence of their former existence could be found only among fossil remains, which are preserved, as we shall attempt to show in a future chapter, in an extremely imperfect and intermittent record. ON THE ORIGIN AND TRANSITION OF ORGANIC BEINGS WITH PECULIAR HABITS AND STRUCTURE. It has been asked by the opponents of such views as I hold, how, for instance, could a land carnivorous animal have been converted into one with aquatic habits; for how could the animal in its transitional state have subsisted? It would be easy to show that there now exist carnivorous animals presenting close intermediate grades from strictly terrestrial to aquatic habits; and as each exists by a struggle for life, it is clear that each must be well adapted to its place in nature. Look at the Mustela vison of North America, which has webbed feet, and which resembles an otter in its fur, short legs, and form of tail; during summer this animal dives for and preys on fish, but during the long winter it leaves the frozen waters, and preys, like other polecats on mice and land animals. If a different case had been taken, and it had been asked how an insectivorous quadruped could possibly have been converted into a flying bat, the question would have been far more difficult to answer. Yet I think such difficulties have little weight. Here, as on other occasions, I lie under a heavy disadvantage, for, out of the many striking cases which I have collected, I can give only one or two instances of transitional habits and structures in allied species; and of diversified habits, either constant or occasional, in the same species. And it seems to me that nothing less than a long list of such cases is sufficient to lessen the difficulty in any particular case like that of the bat. Look at the family of squirrels; here we have the finest gradation from animals with their tails only slightly flattened, and from others, as Sir J. Richardson has remarked, with the posterior part of their bodies rather wide and with the skin on their flanks rather full, to the so-called flying squirrels; and flying squirrels have their limbs and even the base of the tail united by a broad expanse of skin, which serves as a parachute and allows them to glide through the air to an astonishing distance from tree to tree. We cannot doubt that each structure is of use to each kind of squirrel in its own country, by enabling it to escape birds or beasts of prey, or to collect food more quickly, or, as there is reason to believe, to lessen the danger from occasional falls. But it does not follow from this fact that the structure of each squirrel is the best that it is possible to conceive under all possible conditions. Let the climate and vegetation change, let other competing rodents or new beasts of prey immigrate, or old ones become modified, and all analogy would lead us to believe that some, at least, of the squirrels would decrease in numbers or become exterminated, unless they also become modified and improved in structure in a corresponding manner. Therefore, I can see no difficulty, more especially under changing conditions of life, in the continued preservation of individuals with fuller and fuller flank-membranes, each modification being useful, each being propagated, until, by the accumulated effects of this process of natural selection, a perfect so-called flying squirrel was produced. Now look at the Galeopithecus or so-called flying lemur, which was formerly ranked among bats, but is now believed to belong to the Insectivora. An extremely wide flank-membrane stretches from the corners of the jaw to the tail, and includes the limbs with the elongated fingers. This flank-membrane is furnished with an extensor muscle. Although no graduated links of structure, fitted for gliding through the air, now connect the Galeopithecus with the other Insectivora, yet there is no difficulty in supposing that such links formerly existed, and that each was developed in the same manner as with the less perfectly gliding squirrels; each grade of structure having been useful to its possessor. Nor can I see any insuperable difficulty in further believing it possible that the membrane-connected fingers and fore-arm of the Galeopithecus might have been greatly lengthened by natural selection; and this, as far as the organs of flight are concerned, would have converted the animal into a bat. In certain bats in which the wing-membrane extends from the top of the shoulder to the tail and includes the hind-legs, we perhaps see traces of an apparatus originally fitted for gliding through the air rather than for flight. If about a dozen genera of birds were to become extinct, who would have ventured to surmise that birds might have existed which used their wings solely as flappers, like the logger headed duck (Micropterus of Eyton); as fins in the water and as front legs on the land, like the penguin; as sails, like the ostrich; and functionally for no purpose, like the apteryx? Yet the structure of each of these birds is good for it, under the conditions of life to which it is exposed, for each has to live by a struggle: but it is not necessarily the best possible under all possible conditions. It must not be inferred from these remarks that any of the grades of wing-structure here alluded to, which perhaps may all be the result of disuse, indicate the steps by which birds actually acquired their perfect power of flight; but they serve to show what diversified means of transition are at least possible. Seeing that a few members of such water-breathing classes as the Crustacea and Mollusca are adapted to live on the land; and seeing that we have flying birds and mammals, flying insects of the most diversified types, and formerly had flying reptiles, it is conceivable that flying-fish, which now glide far through the air, slightly rising and turning by the aid of their fluttering fins, might have been modified into perfectly winged animals. If this had been effected, who would have ever imagined that in an early transitional state they had been inhabitants of the open ocean, and had used their incipient organs of flight exclusively, so far as we know, to escape being devoured by other fish? When we see any structure highly perfected for any particular habit, as the wings of a bird for flight, we should bear in mind that animals displaying early transitional grades of the structure will seldom have survived to the present day, for they will have been supplanted by their successors, which were gradually rendered more perfect through natural selection. Furthermore, we may conclude that transitional states between structures fitted for very different habits of life will rarely have been developed at an early period in great numbers and under many subordinate forms. Thus, to return to our imaginary illustration of the flying-fish, it does not seem probable that fishes capable of true flight would have been developed under many subordinate forms, for taking prey of many kinds in many ways, on the land and in the water, until their organs of flight had come to a high stage of perfection, so as to have given them a decided advantage over other animals in the battle for life. Hence the chance of discovering species with transitional grades of structure in a fossil condition will always be less, from their having existed in lesser numbers, than in the case of species with fully developed structures. I will now give two or three instances, both of diversified and of changed habits, in the individuals of the same species. In either case it would be easy for natural selection to adapt the structure of the animal to its changed habits, or exclusively to one of its several habits. It is, however, difficult to decide and immaterial for us, whether habits generally change first and structure afterwards; or whether slight modifications of structure lead to changed habits; both probably often occurring almost simultaneously. Of cases of changed habits it will suffice merely to allude to that of the many British insects which now feed on exotic plants, or exclusively on artificial substances. Of diversified habits innumerable instances could be given: I have often watched a tyrant flycatcher (Saurophagus sulphuratus) in South America, hovering over one spot and then proceeding to another, like a kestrel, and at other times standing stationary on the margin of water, and then dashing into it like a kingfisher at a fish. In our own country the larger titmouse (Parus major) may be seen climbing branches, almost like a creeper; it sometimes, like a shrike, kills small birds by blows on the head; and I have many times seen and heard it hammering the seeds of the yew on a branch, and thus breaking them like a nuthatch. In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching, almost like a whale, insects in the water. As we sometimes see individuals following habits different from those proper to their species and to the other species of the same genus, we might expect that such individuals would occasionally give rise to new species, having anomalous habits, and with their structure either slightly or considerably modified from that of their type. And such instances occur in nature. Can a more striking instance of adaptation be given than that of a woodpecker for climbing trees and seizing insects in the chinks of the bark? Yet in North America there are woodpeckers which feed largely on fruit, and others with elongated wings which chase insects on the wing. On the plains of La Plata, where hardly a tree grows, there is a woodpecker (Colaptes campestris) which has two toes before and two behind, a long-pointed tongue, pointed tail-feathers, sufficiently stiff to support the bird in a vertical position on a post, but not so stiff as in the typical wood-peckers, and a straight, strong beak. The beak, however, is not so straight or so strong as in the typical woodpeckers but it is strong enough to bore into wood. Hence this Colaptes, in all the essential parts of its structure, is a woodpecker. Even in such trifling characters as the colouring, the harsh tone of the voice, and undulatory flight, its close blood-relationship to our common woodpecker is plainly declared; yet, as I can assert, not only from my own observations, but from those of the accurate Azara, in certain large districts it does not climb trees, and it makes its nest in holes in banks! In certain other districts, however, this same woodpecker, as Mr. Hudson states, frequents trees, and bores holes in the trunk for its nest. I may mention as another illustration of the varied habits of this genus, that a Mexican Colaptes has been described by De Saussure as boring holes into hard wood in order to lay up a store of acorns. Petrels are the most aerial and oceanic of birds, but, in the quiet sounds of Tierra del Fuego, the Puffinuria berardi, in its general habits, in its astonishing power of diving, in its manner of swimming and of flying when made to take flight, would be mistaken by any one for an auk or a grebe; nevertheless, it is essentially a petrel, but with many parts of its organisation profoundly modified in relation to its new habits of life; whereas the woodpecker of La Plata has had its structure only slightly modified. In the case of the water-ouzel, the acutest observer, by examining its dead body, would never have suspected its sub-aquatic habits; yet this bird, which is allied to the thrush family, subsists by diving,--using its wings under water and grasping stones with its feet. All the members of the great order of Hymenopterous insects are terrestrial, excepting the genus Proctotrupes, which Sir John Lubbock has discovered to be aquatic in its habits; it often enters the water and dives about by the use not of its legs but of its wings, and remains as long as four hours beneath the surface; yet it exhibits no modification in structure in accordance with its abnormal habits. He who believes that each being has been created as we now see it, must occasionally have felt surprise when he has met with an animal having habits and structure not in agreement. What can be plainer than that the webbed feet of ducks and geese are formed for swimming? Yet there are upland geese with webbed feet which rarely go near the water; and no one except Audubon, has seen the frigate-bird, which has all its four toes webbed, alight on the surface of the ocean. On the other hand, grebes and coots are eminently aquatic, although their toes are only bordered by membrane. What seems plainer than that the long toes, not furnished with membrane, of the Grallatores, are formed for walking over swamps and floating plants. The water-hen and landrail are members of this order, yet the first is nearly as aquatic as the coot, and the second is nearly as terrestrial as the quail or partridge. In such cases, and many others could be given, habits have changed without a corresponding change of structure. The webbed feet of the upland goose may be said to have become almost rudimentary in function, though not in structure. In the frigate-bird, the deeply scooped membrane between the toes shows that structure has begun to change. He who believes in separate and innumerable acts of creation may say, that in these cases it has pleased the Creator to cause a being of one type to take the place of one belonging to another type; but this seems to me only restating the fact in dignified language. He who believes in the struggle for existence and in the principle of natural selection, will acknowledge that every organic being is constantly endeavouring to increase in numbers; and that if any one being varies ever so little, either in habits or structure, and thus gains an advantage over some other inhabitant of the same country, it will seize on the place of that inhabitant, however different that may be from its own place. Hence it will cause him no surprise that there should be geese and frigate-birds with webbed feet, living on the dry land and rarely alighting on the water, that there should be long-toed corncrakes, living in meadows instead of in swamps; that there should be woodpeckers where hardly a tree grows; that there should be diving thrushes and diving Hymenoptera, and petrels with the habits of auks. ORGANS OF EXTREME PERFECTION AND COMPLICATION. To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree. When it was first said that the sun stood still and the world turned round, the common sense of mankind declared the doctrine false; but the old saying of Vox populi, vox Dei, as every philosopher knows, cannot be trusted in science. Reason tells me, that if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist, each grade being useful to its possessor, as is certainly the case; if further, the eye ever varies and the variations be inherited, as is likewise certainly the case; and if such variations should be useful to any animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, should not be considered as subversive of the theory. How a nerve comes to be sensitive to light, hardly concerns us more than how life itself originated; but I may remark that, as some of the lowest organisms in which nerves cannot be detected, are capable of perceiving light, it does not seem impossible that certain sensitive elements in their sarcode should become aggregated and developed into nerves, endowed with this special sensibility. In searching for the gradations through which an organ in any species has been perfected, we ought to look exclusively to its lineal progenitors; but this is scarcely ever possible, and we are forced to look to other species and genera of the same group, that is to the collateral descendants from the same parent-form, in order to see what gradations are possible, and for the chance of some gradations having been transmitted in an unaltered or little altered condition. But the state of the same organ in distinct classes may incidentally throw light on the steps by which it has been perfected. The simplest organ which can be called an eye consists of an optic nerve, surrounded by pigment-cells and covered by translucent skin, but without any lens or other refractive body. We may, however, according to M. Jourdain, descend even a step lower and find aggregates of pigment-cells, apparently serving as organs of vision, without any nerves, and resting merely on sarcodic tissue. Eyes of the above simple nature are not capable of distinct vision, and serve only to distinguish light from darkness. In certain star-fishes, small depressions in the layer of pigment which surrounds the nerve are filled, as described by the author just quoted, with transparent gelatinous matter, projecting with a convex surface, like the cornea in the higher animals. He suggests that this serves not to form an image, but only to concentrate the luminous rays and render their perception more easy. In this concentration of the rays we gain the first and by far the most important step towards the formation of a true, picture-forming eye; for we have only to place the naked extremity of the optic nerve, which in some of the lower animals lies deeply buried in the body, and in some near the surface, at the right distance from the concentrating apparatus, and an image will be formed on it. In the great class of the Articulata, we may start from an optic nerve simply coated with pigment, the latter sometimes forming a sort of pupil, but destitute of lens or other optical contrivance. With insects it is now known that the numerous facets on the cornea of their great compound eyes form true lenses, and that the cones include curiously modified nervous filaments. But these organs in the Articulata are so much diversified that Muller formerly made three main classes with seven subdivisions, besides a fourth main class of aggregated simple eyes. When we reflect on these facts, here given much too briefly, with respect to the wide, diversified, and graduated range of structure in the eyes of the lower animals; and when we bear in mind how small the number of all living forms must be in comparison with those which have become extinct, the difficulty ceases to be very great in believing that natural selection may have converted the simple apparatus of an optic nerve, coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the Articulata class. He who will go thus far, ought not to hesitate to go one step further, if he finds on finishing this volume that large bodies of facts, otherwise inexplicable, can be explained by the theory of modification through natural selection; he ought to admit that a structure even as perfect as an eagle's eye might thus be formed, although in this case he does not know the transitional states. It has been objected that in order to modify the eye and still preserve it as a perfect instrument, many changes would have to be effected simultaneously, which, it is assumed, could not be done through natural selection; but as I have attempted to show in my work on the variation of domestic animals, it is not necessary to suppose that the modifications were all simultaneous, if they were extremely slight and gradual. Different kinds of modification would, also, serve for the same general purpose: as Mr. Wallace has remarked, "If a lens has too short or too long a focus, it may be amended either by an alteration of curvature, or an alteration of density; if the curvature be irregular, and the rays do not converge to a point, then any increased regularity of curvature will be an improvement. So the contraction of the iris and the muscular movements of the eye are neither of them essential to vision, but only improvements which might have been added and perfected at any stage of the construction of the instrument." Within the highest division of the animal kingdom, namely, the Vertebrata, we can start from an eye so simple, that it consists, as in the lancelet, of a little sack of transparent skin, furnished with a nerve and lined with pigment, but destitute of any other apparatus. In fishes and reptiles, as Owen has remarked, "The range of gradation of dioptric structures is very great." It is a significant fact that even in man, according to the high authority of Virchow, the beautiful crystalline lens is formed in the embryo by an accumulation of epidermic cells, lying in a sack-like fold of the skin; and the vitreous body is formed from embryonic subcutaneous tissue. To arrive, however, at a just conclusion regarding the formation of the eye, with all its marvellous yet not absolutely perfect characters, it is indispensable that the reason should conquer the imagination; but I have felt the difficulty far to keenly to be surprised at others hesitating to extend the principle of natural selection to so startling a length. It is scarcely possible to avoid comparing the eye with a telescope. We know that this instrument has been perfected by the long-continued efforts of the highest human intellects; and we naturally infer that the eye has been formed by a somewhat analogous process. But may not this inference be presumptuous? Have we any right to assume that the Creator works by intellectual powers like those of man? If we must compare the eye to an optical instrument, we ought in imagination to take a thick layer of transparent tissue, with spaces filled with fluid, and with a nerve sensitive to light beneath, and then suppose every part of this layer to be continually changing slowly in density, so as to separate into layers of different densities and thicknesses, placed at different distances from each other, and with the surfaces of each layer slowly changing in form. Further we must suppose that there is a power, represented by natural selection or the survival of the fittest, always intently watching each slight alteration in the transparent layers; and carefully preserving each which, under varied circumstances, in any way or degree, tends to produce a distincter image. We must suppose each new state of the instrument to be multiplied by the million; each to be preserved until a better is produced, and then the old ones to be all destroyed. In living bodies, variation will cause the slight alteration, generation will multiply them almost infinitely, and natural selection will pick out with unerring skill each improvement. Let this process go on for millions of years; and during each year on millions of individuals of many kinds; and may we not believe that a living optical instrument might thus be formed as superior to one of glass, as the works of the Creator are to those of man? MODES Of TRANSITION. If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case. No doubt many organs exist of which we do not know the transitional grades, more especially if we look to much-isolated species, around which, according to the theory, there has been much extinction. Or again, if we take an organ common to all the members of a class, for in this latter case the organ must have been originally formed at a remote period, since which all the many members of the class have been developed; and in order to discover the early transitional grades through which the organ has passed, we should have to look to very ancient ancestral forms, long since become extinct. We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. Numerous cases could be given among the lower animals of the same organ performing at the same time wholly distinct functions; thus in the larva of the dragon-fly and in the fish Cobites the alimentary canal respires, digests, and excretes. In the Hydra, the animal may be turned inside out, and the exterior surface will then digest and the stomach respire. In such cases natural selection might specialise, if any advantage were thus gained, the whole or part of an organ, which had previously performed two functions, for one function alone, and thus by insensible steps greatly change its nature. Many plants are known which regularly produce at the same time differently constructed flowers; and if such plants were to produce one kind alone, a great change would be effected with comparative suddenness in the character of the species. It is, however, probable that the two sorts of flowers borne by the same plant were originally differentiated by finely graduated steps, which may still be followed in some few cases. Again, two distinct organs, or the same organ under two very different forms, may simultaneously perform in the same individual the same function, and this is an extremely important means of transition: to give one instance--there are fish with gills or branchiae that breathe the air dissolved in the water, at the same time that they breathe free air in their swim-bladders, this latter organ being divided by highly vascular partitions and having a ductus pneumaticus for the supply of air. To give another instance from the vegetable kingdom: plants climb by three distinct means, by spirally twining, by clasping a support with their sensitive tendrils, and by the emission of aerial rootlets; these three means are usually found in distinct groups, but some few species exhibit two of the means, or even all three, combined in the same individual. In all such cases one of the two organs might readily be modified and perfected so as to perform all the work, being aided during the progress of modification by the other organ; and then this other organ might be modified for some other and quite distinct purpose, or be wholly obliterated. The illustration of the swim-bladder in fishes is a good one, because it shows us clearly the highly important fact that an organ originally constructed for one purpose, namely flotation, may be converted into one for a widely different purpose, namely respiration. The swim-bladder has, also, been worked in as an accessory to the auditory organs of certain fishes. All physiologists admit that the swim-bladder is homologous, or "ideally similar" in position and structure with the lungs of the higher vertebrate animals: hence there is no reason to doubt that the swim-bladder has actually been converted into lungs, or an organ used exclusively for respiration. According to this view it may be inferred that all vertebrate animals with true lungs are descended by ordinary generation from an ancient and unknown prototype which was furnished with a floating apparatus or swim-bladder. We can thus, as I infer from Professor Owen's interesting description of these parts, understand the strange fact that every particle of food and drink which we swallow has to pass over the orifice of the trachea, with some risk of falling into the lungs, notwithstanding the beautiful contrivance by which the glottis is closed. In the higher Vertebrata the branchiae have wholly disappeared--but in the embryo the slits on the sides of the neck and the loop-like course of the arteries still mark their former position. But it is conceivable that the now utterly lost branchiae might have been gradually worked in by natural selection for some distinct purpose: for instance, Landois has shown that the wings of insects are developed from the trachea; it is therefore highly probable that in this great class organs which once served for respiration have been actually converted into organs for flight. In considering transitions of organs, it is so important to bear in mind the probability of conversion from one function to another, that I will give another instance. Pedunculated cirripedes have two minute folds of skin, called by me the ovigerous frena, which serve, through the means of a sticky secretion, to retain the eggs until they are hatched within the sack. These cirripedes have no branchiae, the whole surface of the body and of the sack, together with the small frena, serving for respiration. The Balanidae or sessile cirripedes, on the other hand, have no ovigerous frena, the eggs lying loose at the bottom of the sack, within the well-enclosed shell; but they have, in the same relative position with the frena, large, much-folded membranes, which freely communicate with the circulatory lacunae of the sack and body, and which have been considered by all naturalists to act as branchiae. Now I think no one will dispute that the ovigerous frena in the one family are strictly homologous with the branchiae of the other family; indeed, they graduate into each other. Therefore it need not be doubted that the two little folds of skin, which originally served as ovigerous frena, but which, likewise, very slightly aided in the act of respiration, have been gradually converted by natural selection into branchiae, simply through an increase in their size and the obliteration of their adhesive glands. If all pedunculated cirripedes had become extinct, and they have suffered far more extinction than have sessile cirripedes, who would ever have imagined that the branchiae in this latter family had originally existed as organs for preventing the ova from being washed out of the sack? There is another possible mode of transition, namely, through the acceleration or retardation of the period of reproduction. This has lately been insisted on by Professor Cope and others in the United States. It is now known that some animals are capable of reproduction at a very early age, before they have acquired their perfect characters; and if this power became thoroughly well developed in a species, it seems probable that the adult stage of development would sooner or later be lost; and in this case, especially if the larva differed much from the mature form, the character of the species would be greatly changed and degraded. Again, not a few animals, after arriving at maturity, go on changing in character during nearly their whole lives. With mammals, for instance, the form of the skull is often much altered with age, of which Dr. Murie has given some striking instances with seals. Every one knows how the horns of stags become more and more branched, and the plumes of some birds become more finely developed, as they grow older. Professor Cope states that the teeth of certain lizards change much in shape with advancing years. With crustaceans not only many trivial, but some important parts assume a new character, as recorded by Fritz Muller, after maturity. In all such cases--and many could be given--if the age for reproduction were retarded, the character of the species, at least in its adult state, would be modified; nor is it improbable that the previous and earlier stages of development would in some cases be hurried through and finally lost. Whether species have often or ever been modified through this comparatively sudden mode of transition, I can form no opinion; but if this has occurred, it is probable that the differences between the young and the mature, and between the mature and the old, were primordially acquired by graduated steps. SPECIAL DIFFICULTIES OF THE THEORY OF NATURAL SELECTION. Although we must be extremely cautious in concluding that any organ could not have been produced by successive, small, transitional gradations, yet undoubtedly serious cases of difficulty occur. One of the most serious is that of neuter insects, which are often differently constructed from either the males or fertile females; but this case will be treated of in the next chapter. The electric organs of fishes offer another case of special difficulty; for it is impossible to conceive by what steps these wondrous organs have been produced. But this is not surprising, for we do not even know of what use they are. In the gymnotus and torpedo they no doubt serve as powerful means of defence, and perhaps for securing prey; yet in the ray, as observed by Matteucci, an analogous organ in the tail manifests but little electricity, even when the animal is greatly irritated; so little that it can hardly be of any use for the above purposes. Moreover, in the ray, besides the organ just referred to, there is, as Dr. R. McDonnell has shown, another organ near the head, not known to be electrical, but which appears to be the real homologue of the electric battery in the torpedo. It is generally admitted that there exists between these organs and ordinary muscle a close analogy, in intimate structure, in the distribution of the nerves, and in the manner in which they are acted on by various reagents. It should, also, be especially observed that muscular contraction is accompanied by an electrical discharge; and, as Dr. Radcliffe insists, "in the electrical apparatus of the torpedo during rest, there would seem to be a charge in every respect like that which is met with in muscle and nerve during the rest, and the discharge of the torpedo, instead of being peculiar, may be only another form of the discharge which attends upon the action of muscle and motor nerve." Beyond this we cannot at present go in the way of explanation; but as we know so little about the uses of these organs, and as we know nothing about the habits and structure of the progenitors of the existing electric fishes, it would be extremely bold to maintain that no serviceable transitions are possible by which these organs might have been gradually developed. These organs appear at first to offer another and far more serious difficulty; for they occur in about a dozen kinds of fish, of which several are widely remote in their affinities. When the same organ is found in several members of the same class, especially if in members having very different habits of life, we may generally attribute its presence to inheritance from a common ancestor; and its absence in some of the members to loss through disuse or natural selection. So that, if the electric organs had been inherited from some one ancient progenitor, we might have expected that all electric fishes would have been specially related to each other; but this is far from the case. Nor does geology at all lead to the belief that most fishes formerly possessed electric organs, which their modified descendants have now lost. But when we look at the subject more closely, we find in the several fishes provided with electric organs, that these are situated in different parts of the body, that they differ in construction, as in the arrangement of the plates, and, according to Pacini, in the process or means by which the electricity is excited--and lastly, in being supplied with nerves proceeding from different sources, and this is perhaps the most important of all the differences. Hence in the several fishes furnished with electric organs, these cannot be considered as homologous, but only as analogous in function. Consequently there is no reason to suppose that they have been inherited from a common progenitor; for had this been the case they would have closely resembled each other in all respects. Thus the difficulty of an organ, apparently the same, arising in several remotely allied species, disappears, leaving only the lesser yet still great difficulty: namely, by what graduated steps these organs have been developed in each separate group of fishes. The luminous organs which occur in a few insects, belonging to widely different families, and which are situated in different parts of the body, offer, under our present state of ignorance, a difficulty almost exactly parallel with that of the electric organs. Other similar cases could be given; for instance in plants, the very curious contrivance of a mass of pollen-grains, borne on a foot-stalk with an adhesive gland, is apparently the same in Orchis and Asclepias, genera almost as remote as is possible among flowering plants; but here again the parts are not homologous. In all cases of beings, far removed from each other in the scale of organisation, which are furnished with similar and peculiar organs, it will be found that although the general appearance and function of the organs may be the same, yet fundamental differences between them can always be detected. For instance, the eyes of Cephalopods or cuttle-fish and of vertebrate animals appear wonderfully alike; and in such widely sundered groups no part of this resemblance can be due to inheritance from a common progenitor. Mr. Mivart has advanced this case as one of special difficulty, but I am unable to see the force of his argument. An organ for vision must be formed of transparent tissue, and must include some sort of lens for throwing an image at the back of a darkened chamber. Beyond this superficial resemblance, there is hardly any real similarity between the eyes of cuttle-fish and vertebrates, as may be seen by consulting Hensen's admirable memoir on these organs in the Cephalopoda. It is impossible for me here to enter on details, but I may specify a few of the points of difference. The crystalline lens in the higher cuttle-fish consists of two parts, placed one behind the other like two lenses, both having a very different structure and disposition to what occurs in the vertebrata. The retina is wholly different, with an actual inversion of the elemental parts, and with a large nervous ganglion included within the membranes of the eye. The relations of the muscles are as different as it is possible to conceive, and so in other points. Hence it is not a little difficult to decide how far even the same terms ought to be employed in describing the eyes of the Cephalopoda and Vertebrata. It is, of course, open to any one to deny that the eye in either case could have been developed through the natural selection of successive slight variations; but if this be admitted in the one case it is clearly possible in the other; and fundamental differences of structure in the visual organs of two groups might have been anticipated, in accordance with this view of their manner of formation. As two men have sometimes independently hit on the same invention, so in the several foregoing cases it appears that natural selection, working for the good of each being, and taking advantage of all favourable variations, has produced similar organs, as far as function is concerned, in distinct organic beings, which owe none of their structure in common to inheritance from a common progenitor. Fritz Muller, in order to test the conclusions arrived at in this volume, has followed out with much care a nearly similar line of argument. Several families of crustaceans include a few species, possessing an air-breathing apparatus and fitted to live out of the water. In two of these families, which were more especially examined by Muller, and which are nearly related to each other, the species agree most closely in all important characters: namely in their sense organs, circulating systems, in the position of the tufts of hair within their complex stomachs, and lastly in the whole structure of the water-breathing branchiae, even to the microscopical hooks by which they are cleansed. Hence it might have been expected that in the few species belonging to both families which live on the land, the equally important air-breathing apparatus would have been the same; for why should this one apparatus, given for the same purpose, have been made to differ, while all the other important organs were closely similar, or rather, identical. Fritz Muller argues that this close similarity in so many points of structure must, in accordance with the views advanced by me, be accounted for by inheritance from a common progenitor. But as the vast majority of the species in the above two families, as well as most other crustaceans, are aquatic in their habits, it is improbable in the highest degree that their common progenitor should have been adapted for breathing air. Muller was thus led carefully to examine the apparatus in the air-breathing species; and he found it to differ in each in several important points, as in the position of the orifices, in the manner in which they are opened and closed, and in some accessory details. Now such differences are intelligible, and might even have been expected, on the supposition that species belonging to distinct families had slowly become adapted to live more and more out of water, and to breathe the air. For these species, from belonging to distinct families, would have differed to a certain extent, and in accordance with the principle that the nature of each variation depends on two factors, viz., the nature of the organism and that of the surrounding conditions, their variability assuredly would not have been exactly the same. Consequently natural selection would have had different materials or variations to work on, in order to arrive at the same functional result; and the structures thus acquired would almost necessarily have differed. On the hypothesis of separate acts of creation the whole case remains unintelligible. This line of argument seems to have had great weight in leading Fritz Muller to accept the views maintained by me in this volume. Another distinguished zoologist, the late Professor Claparede, has argued in the same manner, and has arrived at the same result. He shows that there are parasitic mites (Acaridae), belonging to distinct sub-families and families, which are furnished with hair-claspers. These organs must have been independently developed, as they could not have been inherited from a common progenitor; and in the several groups they are formed by the modification of the fore legs, of the hind legs, of the maxillae or lips, and of appendages on the under side of the hind part of the body. In the foregoing cases, we see the same end gained and the same function performed, in beings not at all or only remotely allied, by organs in appearance, though not in development, closely similar. On the other hand, it is a common rule throughout nature that the same end should be gained, even sometimes in the case of closely related beings, by the most diversified means. How differently constructed is the feathered wing of a bird and the membrane-covered wing of a bat; and still more so the four wings of a butterfly, the two wings of a fly, and the two wings with the elytra of a beetle. Bivalve shells are made to open and shut, but on what a number of patterns is the hinge constructed, from the long row of neatly interlocking teeth in a Nucula to the simple ligament of a Mussel! Seeds are disseminated by their minuteness, by their capsule being converted into a light balloon-like envelope, by being embedded in pulp or flesh, formed of the most diverse parts, and rendered nutritious, as well as conspicuously coloured, so as to attract and be devoured by birds, by having hooks and grapnels of many kinds and serrated awns, so as to adhere to the fur of quadrupeds, and by being furnished with wings and plumes, as different in shape as they are elegant in structure, so as to be wafted by every breeze. I will give one other instance: for this subject of the same end being gained by the most diversified means well deserves attention. Some authors maintain that organic beings have been formed in many ways for the sake of mere variety, almost like toys in a shop, but such a view of nature is incredible. With plants having separated sexes, and with those in which, though hermaphrodites, the pollen does not spontaneously fall on the stigma, some aid is necessary for their fertilisation. With several kinds this is effected by the pollen-grains, which are light and incoherent, being blown by the wind through mere chance on to the stigma; and this is the simplest plan which can well be conceived. An almost equally simple, though very different plan occurs in many plants in which a symmetrical flower secretes a few drops of nectar, and is consequently visited by insects; and these carry the pollen from the anthers to the stigma. From this simple stage we may pass through an inexhaustible number of contrivances, all for the same purpose and effected in essentially the same manner, but entailing changes in every part of the flower. The nectar may be stored in variously shaped receptacles, with the stamens and pistils modified in many ways, sometimes forming trap-like contrivances, and sometimes capable of neatly adapted movements through irritability or elasticity. From such structures we may advance till we come to such a case of extraordinary adaptation as that lately described by Dr. Cruger in the Coryanthes. This orchid has part of its labellum or lower lip hollowed out into a great bucket, into which drops of almost pure water continually fall from two secreting horns which stand above it; and when the bucket is half-full, the water overflows by a spout on one side. The basal part of the labellum stands over the bucket, and is itself hollowed out into a sort of chamber with two lateral entrances; within this chamber there are curious fleshy ridges. The most ingenious man, if he had not witnessed what takes place, could never have imagined what purpose all these parts serve. But Dr. Cruger saw crowds of large humble-bees visiting the gigantic flowers of this orchid, not in order to suck nectar, but to gnaw off the ridges within the chamber above the bucket; in doing this they frequently pushed each other into the bucket, and their wings being thus wetted they could not fly away, but were compelled to crawl out through the passage formed by the spout or overflow. Dr. Cruger saw a "continual procession" of bees thus crawling out of their involuntary bath. The passage is narrow, and is roofed over by the column, so that a bee, in forcing its way out, first rubs its back against the viscid stigma and then against the viscid glands of the pollen-masses. The pollen-masses are thus glued to the back of the bee which first happens to crawl out through the passage of a lately expanded flower, and are thus carried away. Dr. Cruger sent me a flower in spirits of wine, with a bee which he had killed before it had quite crawled out, with a pollen-mass still fastened to its back. When the bee, thus provided, flies to another flower, or to the same flower a second time, and is pushed by its comrades into the bucket and then crawls out by the passage, the pollen-mass necessarily comes first into contact with the viscid stigma, and adheres to it, and the flower is fertilised. Now at last we see the full use of every part of the flower, of the water-secreting horns of the bucket half-full of water, which prevents the bees from flying away, and forces them to crawl out through the spout, and rub against the properly placed viscid pollen-masses and the viscid stigma. The construction of the flower in another closely allied orchid, namely, the Catasetum, is widely different, though serving the same end; and is equally curious. Bees visit these flowers, like those of the Coryanthes, in order to gnaw the labellum; in doing this they inevitably touch a long, tapering, sensitive projection, or, as I have called it, the antenna. This antenna, when touched, transmits a sensation or vibration to a certain membrane which is instantly ruptured; this sets free a spring by which the pollen-mass is shot forth, like an arrow, in the right direction, and adheres by its viscid extremity to the back of the bee. The pollen-mass of the male plant (for the sexes are separate in this orchid) is thus carried to the flower of the female plant, where it is brought into contact with the stigma, which is viscid enough to break certain elastic threads, and retain the pollen, thus effecting fertilisation. How, it may be asked, in the foregoing and in innumerable other instances, can we understand the graduated scale of complexity and the multifarious means for gaining the same end. The answer no doubt is, as already remarked, that when two forms vary, which already differ from each other in some slight degree, the variability will not be of the same exact nature, and consequently the results obtained through natural selection for the same general purpose will not be the same. We should also bear in mind that every highly developed organism has passed through many changes; and that each modified structure tends to be inherited, so that each modification will not readily be quite lost, but may be again and again further altered. Hence, the structure of each part of each species, for whatever purpose it may serve, is the sum of many inherited changes, through which the species has passed during its successive adaptations to changed habits and conditions of life. Finally, then, although in many cases it is most difficult even to conjecture by what transitions organs could have arrived at their present state; yet, considering how small the proportion of living and known forms is to the extinct and unknown, I have been astonished how rarely an organ can be named, towards which no transitional grade is known to lead. It is certainly true, that new organs appearing as if created for some special purpose rarely or never appear in any being; as indeed is shown by that old, but somewhat exaggerated, canon in natural history of "Natura non facit saltum." We meet with this admission in the writings of almost every experienced naturalist; or, as Milne Edwards has well expressed it, "Nature is prodigal in variety, but niggard in innovation." Why, on the theory of Creation, should there be so much variety and so little real novelty? Why should all the parts and organs of many independent beings, each supposed to have been separately created for its own proper place in nature, be so commonly linked together by graduated steps? Why should not Nature take a sudden leap from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap, but must advance by the short and sure, though slow steps. ORGANS OF LITTLE APPARENT IMPORTANCE, AS AFFECTED BY NATURAL SELECTION. As natural selection acts by life and death, by the survival of the fittest, and by the destruction of the less well-fitted individuals, I have sometimes felt great difficulty in understanding the origin or formation of parts of little importance; almost as great, though of a very different kind, as in the case of the most perfect and complex organs. In the first place, we are much too ignorant in regard to the whole economy of any one organic being to say what slight modifications would be of importance or not. In a former chapter I have given instances of very trifling characters, such as the down on fruit and the colour of its flesh, the colour of the skin and hair of quadrupeds, which, from being correlated with constitutional differences, or from determining the attacks of insects, might assuredly be acted on by natural selection. The tail of the giraffe looks like an artificially constructed fly-flapper; and it seems at first incredible that this could have been adapted for its present purpose by successive slight modifications, each better and better fitted, for so trifling an object as to drive away flies; yet we should pause before being too positive even in this case, for we know that the distribution and existence of cattle and other animals in South America absolutely depend on their power of resisting the attacks of insects: so that individuals which could by any means defend themselves from these small enemies, would be able to range into new pastures and thus gain a great advantage. It is not that the larger quadrupeds are actually destroyed (except in some rare cases) by flies, but they are incessantly harassed and their strength reduced, so that they are more subject to disease, or not so well enabled in a coming dearth to search for food, or to escape from beasts of prey. Organs now of trifling importance have probably in some cases been of high importance to an early progenitor, and, after having been slowly perfected at a former period, have been transmitted to existing species in nearly the same state, although now of very slight use; but any actually injurious deviations in their structure would of course have been checked by natural selection. Seeing how important an organ of locomotion the tail is in most aquatic animals, its general presence and use for many purposes in so many land animals, which in their lungs or modified swim-bladders betray their aquatic origin, may perhaps be thus accounted for. A well-developed tail having been formed in an aquatic animal, it might subsequently come to be worked in for all sorts of purposes, as a fly-flapper, an organ of prehension, or as an aid in turning, as in the case of the dog, though the aid in this latter respect must be slight, for the hare, with hardly any tail, can double still more quickly. In the second place, we may easily err in attributing importance to characters, and in believing that they have been developed through natural selection. We must by no means overlook the effects of the definite action of changed conditions of life, of so-called spontaneous variations, which seem to depend in a quite subordinate degree on the nature of the conditions, of the tendency to reversion to long-lost characters, of the complex laws of growth, such as of correlation, comprehension, of the pressure of one part on another, etc., and finally of sexual selection, by which characters of use to one sex are often gained and then transmitted more or less perfectly to the other sex, though of no use to the sex. But structures thus indirectly gained, although at first of no advantage to a species, may subsequently have been taken advantage of by its modified descendants, under new conditions of life and newly acquired habits. If green woodpeckers alone had existed, and we did not know that there were many black and pied kinds, I dare say that we should have thought that the green colour was a beautiful adaptation to conceal this tree-frequenting bird from its enemies; and consequently that it was a character of importance, and had been acquired through natural selection; as it is, the colour is probably in chief part due to sexual selection. A trailing palm in the Malay Archipelago climbs the loftiest trees by the aid of exquisitely constructed hooks clustered around the ends of the branches, and this contrivance, no doubt, is of the highest service to the plant; but as we see nearly similar hooks on many trees which are not climbers, and which, as there is reason to believe from the distribution of the thorn-bearing species in Africa and South America, serve as a defence against browsing quadrupeds, so the spikes on the palm may at first have been developed for this object, and subsequently have been improved and taken advantage of by the plant, as it underwent further modification and became a climber. The naked skin on the head of a vulture is generally considered as a direct adaptation for wallowing in putridity; and so it may be, or it may possibly be due to the direct action of putrid matter; but we should be very cautious in drawing any such inference, when we see that the skin on the head of the clean-feeding male turkey is likewise naked. The sutures in the skulls of young mammals have been advanced as a beautiful adaptation for aiding parturition, and no doubt they facilitate, or may be indispensable for this act; but as sutures occur in the skulls of young birds and reptiles, which have only to escape from a broken egg, we may infer that this structure has arisen from the laws of growth, and has been taken advantage of in the parturition of the higher animals. We are profoundly ignorant of the cause of each slight variation or individual difference; and we are immediately made conscious of this by reflecting on the differences between the breeds of our domesticated animals in different countries, more especially in the less civilized countries, where there has been but little methodical selection. Animals kept by savages in different countries often have to struggle for their own subsistence, and are exposed to a certain extent to natural selection, and individuals with slightly different constitutions would succeed best under different climates. With cattle susceptibility to the attacks of flies is correlated with colour, as is the liability to be poisoned by certain plants; so that even colour would be thus subjected to the action of natural selection. Some observers are convinced that a damp climate affects the growth of the hair, and that with the hair the horns are correlated. Mountain breeds always differ from lowland breeds; and a mountainous country would probably affect the hind limbs from exercising them more, and possibly even the form of the pelvis; and then by the law of homologous variation, the front limbs and the head would probably be affected. The shape, also, of the pelvis might affect by pressure the shape of certain parts of the young in the womb. The laborious breathing necessary in high regions tends, as we have good reason to believe, to increase the size of the chest; and again correlation would come into play. The effects of lessened exercise, together with abundant food, on the whole organisation is probably still more important, and this, as H. von Nathusius has lately shown in his excellent Treatise, is apparently one chief cause of the great modification which the breeds of swine have undergone. But we are far too ignorant to speculate on the relative importance of the several known and unknown causes of variation; and I have made these remarks only to show that, if we are unable to account for the characteristic differences of our several domestic breeds, which nevertheless are generally admitted to have arisen through ordinary generation from one or a few parent-stocks, we ought not to lay too much stress on our ignorance of the precise cause of the slight analogous differences between true species. UTILITARIAN DOCTRINE, HOW FAR TRUE: BEAUTY, HOW ACQUIRED. The foregoing remarks lead me to say a few words on the protest lately made by some naturalists against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that many structures have been created for the sake of beauty, to delight man or the Creator (but this latter point is beyond the scope of scientific discussion), or for the sake of mere variety, a view already discussed. Such doctrines, if true, would be absolutely fatal to my theory. I fully admit that many structures are now of no direct use to their possessors, and may never have been of any use to their progenitors; but this does not prove that they were formed solely for beauty or variety. No doubt the definite action of changed conditions, and the various causes of modifications, lately specified, have all produced an effect, probably a great effect, independently of any advantage thus gained. But a still more important consideration is that the chief part of the organisation of every living creature is due to inheritance; and consequently, though each being assuredly is well fitted for its place in nature, many structures have now no very close and direct relation to present habits of life. Thus, we can hardly believe that the webbed feet of the upland goose, or of the frigate-bird, are of special use to these birds; we cannot believe that the similar bones in the arm of the monkey, in the fore leg of the horse, in the wing of the bat, and in the flipper of the seal, are of special use to these animals. We may safely attribute these structures to inheritance. But webbed feet no doubt were as useful to the progenitor of the upland goose and of the frigate-bird, as they now are to the most aquatic of living birds. So we may believe that the progenitor of the seal did not possess a flipper, but a foot with five toes fitted for walking or grasping; and we may further venture to believe that the several bones in the limbs of the monkey, horse and bat, were originally developed, on the principle of utility, probably through the reduction of more numerous bones in the fin of some ancient fish-like progenitor of the whole class. It is scarcely possible to decide how much allowance ought to be made for such causes of change, as the definite action of external conditions, so-called spontaneous variations, and the complex laws of growth; but with these important exceptions, we may conclude that the structure of every living creature either now is, or was formerly, of some direct or indirect use to its possessor. With respect to the belief that organic beings have been created beautiful for the delight of man--a belief which it has been pronounced is subversive of my whole theory--I may first remark that the sense of beauty obviously depends on the nature of the mind, irrespective of any real quality in the admired object; and that the idea of what is beautiful, is not innate or unalterable. We see this, for instance, in the men of different races admiring an entirely different standard of beauty in their women. If beautiful objects had been created solely for man's gratification, it ought to be shown that before man appeared there was less beauty on the face of the earth than since he came on the stage. Were the beautiful volute and cone shells of the Eocene epoch, and the gracefully sculptured ammonites of the Secondary period, created that man might ages afterwards admire them in his cabinet? Few objects are more beautiful than the minute siliceous cases of the diatomaceae: were these created that they might be examined and admired under the higher powers of the microscope? The beauty in this latter case, and in many others, is apparently wholly due to symmetry of growth. Flowers rank among the most beautiful productions of nature; but they have been rendered conspicuous in contrast with the green leaves, and in consequence at the same time beautiful, so that they may be easily observed by insects. I have come to this conclusion from finding it an invariable rule that when a flower is fertilised by the wind it never has a gaily-coloured corolla. Several plants habitually produce two kinds of flowers; one kind open and coloured so as to attract insects; the other closed, not coloured, destitute of nectar, and never visited by insects. Hence, we may conclude that, if insects had not been developed on the face of the earth, our plants would not have been decked with beautiful flowers, but would have produced only such poor flowers as we see on our fir, oak, nut and ash trees, on grasses, spinach, docks and nettles, which are all fertilised through the agency of the wind. A similar line of argument holds good with fruits; that a ripe strawberry or cherry is as pleasing to the eye as to the palate--that the gaily-coloured fruit of the spindle-wood tree and the scarlet berries of the holly are beautiful objects--will be admitted by everyone. But this beauty serves merely as a guide to birds and beasts, in order that the fruit may be devoured and the matured seeds disseminated. I infer that this is the case from having as yet found no exception to the rule that seeds are always thus disseminated when embedded within a fruit of any kind (that is within a fleshy or pulpy envelope), if it be coloured of any brilliant tint, or rendered conspicuous by being white or black. On the other hand, I willingly admit that a great number of male animals, as all our most gorgeous birds, some fishes, reptiles, and mammals, and a host of magnificently coloured butterflies, have been rendered beautiful for beauty's sake. But this has been effected through sexual selection, that is, by the more beautiful males having been continually preferred by the females, and not for the delight of man. So it is with the music of birds. We may infer from all this that a nearly similar taste for beautiful colours and for musical sounds runs through a large part of the animal kingdom. When the female is as beautifully coloured as the male, which is not rarely the case with birds and butterflies, the cause apparently lies in the colours acquired through sexual selection having been transmitted to both sexes, instead of to the males alone. How the sense of beauty in its simplest form--that is, the reception of a peculiar kind of pleasure from certain colours, forms and sounds--was first developed in the mind of man and of the lower animals, is a very obscure subject. The same sort of difficulty is presented if we enquire how it is that certain flavours and odours give pleasure, and others displeasure. Habit in all these cases appears to have come to a certain extent into play; but there must be some fundamental cause in the constitution of the nervous system in each species. Natural selection cannot possibly produce any modification in a species exclusively for the good of another species; though throughout nature one species incessantly takes advantage of, and profits by the structures of others. But natural selection can and does often produce structures for the direct injury of other animals, as we see in the fang of the adder, and in the ovipositor of the ichneumon, by which its eggs are deposited in the living bodies of other insects. If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection. Although many statements may be found in works on natural history to this effect, I cannot find even one which seems to me of any weight. It is admitted that the rattlesnake has a poison-fang for its own defence and for the destruction of its prey; but some authors suppose that at the same time it is furnished with a rattle for its own injury, namely, to warn its prey. I would almost as soon believe that the cat curls the end of its tail when preparing to spring, in order to warn the doomed mouse. It is a much more probable view that the rattlesnake uses its rattle, the cobra expands its frill and the puff-adder swells while hissing so loudly and harshly, in order to alarm the many birds and beasts which are known to attack even the most venomous species. Snakes act on the same principle which makes the hen ruffle her feathers and expand her wings when a dog approaches her chickens. But I have not space here to enlarge on the many ways by which animals endeavour to frighten away their enemies. Natural selection will never produce in a being any structure more injurious than beneficial to that being, for natural selection acts solely by and for the good of each. No organ will be formed, as Paley has remarked, for the purpose of causing pain or for doing an injury to its possessor. If a fair balance be struck between the good and evil caused by each part, each will be found on the whole advantageous. After the lapse of time, under changing conditions of life, if any part comes to be injurious, it will be modified; or if it be not so, the being will become extinct, as myriads have become extinct. Natural selection tends only to make each organic being as perfect as, or slightly more perfect than the other inhabitants of the same country with which it comes into competition. And we see that this is the standard of perfection attained under nature. The endemic productions of New Zealand, for instance, are perfect, one compared with another; but they are now rapidly yielding before the advancing legions of plants and animals introduced from Europe. Natural selection will not produce absolute perfection, nor do we always meet, as far as we can judge, with this high standard under nature. The correction for the aberration of light is said by Muller not to be perfect even in that most perfect organ, the human eye. Helmholtz, whose judgment no one will dispute, after describing in the strongest terms the wonderful powers of the human eye, adds these remarkable words: "That which we have discovered in the way of inexactness and imperfection in the optical machine and in the image on the retina, is as nothing in comparison with the incongruities which we have just come across in the domain of the sensations. One might say that nature has taken delight in accumulating contradictions in order to remove all foundation from the theory of a pre-existing harmony between the external and internal worlds." If our reason leads us to admire with enthusiasm a multitude of inimitable contrivances in nature, this same reason tells us, though we may easily err on both sides, that some other contrivances are less perfect. Can we consider the sting of the bee as perfect, which, when used against many kinds of enemies, cannot be withdrawn, owing to the backward serratures, and thus inevitably causes the death of the insect by tearing out its viscera? If we look at the sting of the bee, as having existed in a remote progenitor, as a boring and serrated instrument, like that in so many members of the same great order, and that it has since been modified but not perfected for its present purpose, with the poison originally adapted for some other object, such as to produce galls, since intensified, we can perhaps understand how it is that the use of the sting should so often cause the insect's own death: for if on the whole the power of stinging be useful to the social community, it will fulfil all the requirements of natural selection, though it may cause the death of some few members. If we admire the truly wonderful power of scent by which the males of many insects find their females, can we admire the production for this single purpose of thousands of drones, which are utterly useless to the community for any other purpose, and which are ultimately slaughtered by their industrious and sterile sisters? It may be difficult, but we ought to admire the savage instinctive hatred of the queen-bee, which urges her to destroy the young queens, her daughters, as soon as they are born, or to perish herself in the combat; for undoubtedly this is for the good of the community; and maternal love or maternal hatred, though the latter fortunately is most rare, is all the same to the inexorable principles of natural selection. If we admire the several ingenious contrivances by which orchids and many other plants are fertilised through insect agency, can we consider as equally perfect the elaboration of dense clouds of pollen by our fir-trees, so that a few granules may be wafted by chance on to the ovules? SUMMARY: THE LAW OF UNITY OF TYPE AND OF THE CONDITIONS OF EXISTENCE EMBRACED BY THE THEORY OF NATURAL SELECTION. We have in this chapter discussed some of the difficulties and objections which may be urged against the theory. Many of them are serious; but I think that in the discussion light has been thrown on several facts, which on the belief of independent acts of creation are utterly obscure. We have seen that species at any one period are not indefinitely variable, and are not linked together by a multitude of intermediate gradations, partly because the process of natural selection is always very slow, and at any one time acts only on a few forms; and partly because the very process of natural selection implies the continual supplanting and extinction of preceding and intermediate gradations. Closely allied species, now living on a continuous area, must often have been formed when the area was not continuous, and when the conditions of life did not insensibly graduate away from one part to another. When two varieties are formed in two districts of a continuous area, an intermediate variety will often be formed, fitted for an intermediate zone; but from reasons assigned, the intermediate variety will usually exist in lesser numbers than the two forms which it connects; consequently the two latter, during the course of further modification, from existing in greater numbers, will have a great advantage over the less numerous intermediate variety, and will thus generally succeed in supplanting and exterminating it. We have seen in this chapter how cautious we should be in concluding that the most different habits of life could not graduate into each other; that a bat, for instance, could not have been formed by natural selection from an animal which at first only glided through the air. We have seen that a species under new conditions of life may change its habits, or it may have diversified habits, with some very unlike those of its nearest congeners. Hence we can understand, bearing in mind that each organic being is trying to live wherever it can live, how it has arisen that there are upland geese with webbed feet, ground woodpeckers, diving thrushes, and petrels with the habits of auks. Although the belief that an organ so perfect as the eye could have been formed by natural selection, is enough to stagger any one; yet in the case of any organ, if we know of a long series of gradations in complexity, each good for its possessor, then under changing conditions of life, there is no logical impossibility in the acquirement of any conceivable degree of perfection through natural selection. In the cases in which we know of no intermediate or transitional states, we should be extremely cautious in concluding that none can have existed, for the metamorphoses of many organs show what wonderful changes in function are at least possible. For instance, a swim-bladder has apparently been converted into an air-breathing lung. The same organ having performed simultaneously very different functions, and then having been in part or in whole specialised for one function; and two distinct organs having performed at the same time the same function, the one having been perfected whilst aided by the other, must often have largely facilitated transitions. We have seen that in two beings widely remote from each other in the natural scale, organs serving for the same purpose and in external appearance closely similar may have been separately and independently formed; but when such organs are closely examined, essential differences in their structure can almost always be detected; and this naturally follows from the principle of natural selection. On the other hand, the common rule throughout nature is infinite diversity of structure for gaining the same end; and this again naturally follows from the same great principle. In many cases we are far too ignorant to be enabled to assert that a part or organ is so unimportant for the welfare of a species, that modifications in its structure could not have been slowly accumulated by means of natural selection. In many other cases, modifications are probably the direct result of the laws of variation or of growth, independently of any good having been thus gained. But even such structures have often, as we may feel assured, been subsequently taken advantage of, and still further modified, for the good of species under new conditions of life. We may, also, believe that a part formerly of high importance has frequently been retained (as the tail of an aquatic animal by its terrestrial descendants), though it has become of such small importance that it could not, in its present state, have been acquired by means of natural selection. Natural selection can produce nothing in one species for the exclusive good or injury of another; though it may well produce parts, organs, and excretions highly useful or even indispensable, or highly injurious to another species, but in all cases at the same time useful to the possessor. In each well-stocked country natural selection acts through the competition of the inhabitants and consequently leads to success in the battle for life, only in accordance with the standard of that particular country. Hence the inhabitants of one country, generally the smaller one, often yield to the inhabitants of another and generally the larger country. For in the larger country there will have existed more individuals, and more diversified forms, and the competition will have been severer, and thus the standard of perfection will have been rendered higher. Natural selection will not necessarily lead to absolute perfection; nor, as far as we can judge by our limited faculties, can absolute perfection be everywhere predicated. On the theory of natural selection we can clearly understand the full meaning of that old canon in natural history, "Natura non facit saltum." This canon, if we look to the present inhabitants alone of the world, is not strictly correct; but if we include all those of past times, whether known or unknown, it must on this theory be strictly true. It is generally acknowledged that all organic beings have been formed on two great laws--Unity of Type, and the Conditions of Existence. By unity of type is meant that fundamental agreement in structure which we see in organic beings of the same class, and which is quite independent of their habits of life. On my theory, unity of type is explained by unity of descent. The expression of conditions of existence, so often insisted on by the illustrious Cuvier, is fully embraced by the principle of natural selection. For natural selection acts by either now adapting the varying parts of each being to its organic and inorganic conditions of life; or by having adapted them during past periods of time: the adaptations being aided in many cases by the increased use or disuse of parts, being affected by the direct action of external conditions of life, and subjected in all cases to the several laws of growth and variation. Hence, in fact, the law of the Conditions of Existence is the higher law; as it includes, through the inheritance of former variations and adaptations, that of Unity of Type. CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION. Longevity--Modifications not necessarily simultaneous--Modifications apparently of no direct service--Progressive development--Characters of small functional importance, the most constant--Supposed incompetence of natural selection to account for the incipient stages of useful structures--Causes which interfere with the acquisition through natural selection of useful structures--Gradations of structure with changed functions--Widely different organs in members of the same class, developed from one and the same source--Reasons for disbelieving in great and abrupt modifications. I will devote this chapter to the consideration of various miscellaneous objections which have been advanced against my views, as some of the previous discussions may thus be made clearer; but it would be useless to discuss all of them, as many have been made by writers who have not taken the trouble to understand the subject. Thus a distinguished German naturalist has asserted that the weakest part of my theory is, that I consider all organic beings as imperfect: what I have really said is, that all are not as perfect as they might have been in relation to their conditions; and this is shown to be the case by so many native forms in many quarters of the world having yielded their places to intruding foreigners. Nor can organic beings, even if they were at any one time perfectly adapted to their conditions of life, have remained so, when their conditions changed, unless they themselves likewise changed; and no one will dispute that the physical conditions of each country, as well as the number and kinds of its inhabitants, have undergone many mutations. A critic has lately insisted, with some parade of mathematical accuracy, that longevity is a great advantage to all species, so that he who believes in natural selection "must arrange his genealogical tree" in such a manner that all the descendants have longer lives than their progenitors! Cannot our critics conceive that a biennial plant or one of the lower animals might range into a cold climate and perish there every winter; and yet, owing to advantages gained through natural selection, survive from year to year by means of its seeds or ova? Mr. E. Ray Lankester has recently discussed this subject, and he concludes, as far as its extreme complexity allows him to form a judgment, that longevity is generally related to the standard of each species in the scale of organisation, as well as to the amount of expenditure in reproduction and in general activity. And these conditions have, it is probable, been largely determined through natural selection. It has been argued that, as none of the animals and plants of Egypt, of which we know anything, have changed during the last three or four thousand years, so probably have none in any part of the world. But, as Mr. G.H. Lewes has remarked, this line of argument proves too much, for the ancient domestic races figured on the Egyptian monuments, or embalmed, are closely similar or even identical with those now living; yet all naturalists admit that such races have been produced through the modification of their original types. The many animals which have remained unchanged since the commencement of the glacial period, would have been an incomparably stronger case, for these have been exposed to great changes of climate and have migrated over great distances; whereas, in Egypt, during the last several thousand years, the conditions of life, as far as we know, have remained absolutely uniform. The fact of little or no modification having been effected since the glacial period, would have been of some avail against those who believe in an innate and necessary law of development, but is powerless against the doctrine of natural selection or the survival of the fittest, which implies that when variations or individual differences of a beneficial nature happen to arise, these will be preserved; but this will be effected only under certain favourable circumstances. The celebrated palaeontologist, Bronn, at the close of his German translation of this work, asks how, on the principle of natural selection, can a variety live side by side with the parent species? If both have become fitted for slightly different habits of life or conditions, they might live together; and if we lay on one side polymorphic species, in which the variability seems to be of a peculiar nature, and all mere temporary variations, such as size, albinism, etc., the more permanent varieties are generally found, as far as I can discover, inhabiting distinct stations, such as high land or low land, dry or moist districts. Moreover, in the case of animals which wander much about and cross freely, their varieties seem to be generally confined to distinct regions. Bronn also insists that distinct species never differ from each other in single characters, but in many parts; and he asks, how it always comes that many parts of the organisation should have been modified at the same time through variation and natural selection? But there is no necessity for supposing that all the parts of any being have been simultaneously modified. The most striking modifications, excellently adapted for some purpose, might, as was formerly remarked, be acquired by successive variations, if slight, first in one part and then in another; and as they would be transmitted all together, they would appear to us as if they had been simultaneously developed. The best answer, however, to the above objection is afforded by those domestic races which have been modified, chiefly through man's power of selection, for some special purpose. Look at the race and dray-horse, or at the greyhound and mastiff. Their whole frames, and even their mental characteristics, have been modified; but if we could trace each step in the history of their transformation--and the latter steps can be traced--we should not see great and simultaneous changes, but first one part and then another slightly modified and improved. Even when selection has been applied by man to some one character alone--of which our cultivated plants offer the best instances--it will invariably be found that although this one part, whether it be the flower, fruit, or leaves, has been greatly changed, almost all the other parts have been slightly modified. This may be attributed partly to the principle of correlated growth, and partly to so-called spontaneous variation. A much more serious objection has been urged by Bronn, and recently by Broca, namely, that many characters appear to be of no service whatever to their possessors, and therefore cannot have been influenced through natural selection. Bronn adduces the length of the ears and tails in the different species of hares and mice--the complex folds of enamel in the teeth of many animals, and a multitude of analogous cases. With respect to plants, this subject has been discussed by Nageli in an admirable essay. He admits that natural selection has effected much, but he insists that the families of plants differ chiefly from each other in morphological characters, which appear to be quite unimportant for the welfare of the species. He consequently believes in an innate tendency towards progressive and more perfect development. He specifies the arrangement of the cells in the tissues, and of the leaves on the axis, as cases in which natural selection could not have acted. To these may be added the numerical divisions in the parts of the flower, the position of the ovules, the shape of the seed, when not of any use for dissemination, etc. There is much force in the above objection. Nevertheless, we ought, in the first place, to be extremely cautious in pretending to decide what structures now are, or have formerly been, of use to each species. In the second place, it should always be borne in mind that when one part is modified, so will be other parts, through certain dimly seen causes, such as an increased or diminished flow of nutriment to a part, mutual pressure, an early developed part affecting one subsequently developed, and so forth--as well as through other causes which lead to the many mysterious cases of correlation, which we do not in the least understand. These agencies may be all grouped together, for the sake of brevity, under the expression of the laws of growth. In the third place, we have to allow for the direct and definite action of changed conditions of life, and for so-called spontaneous variations, in which the nature of the conditions apparently plays a quite subordinate part. Bud-variations, such as the appearance of a moss-rose on a common rose, or of a nectarine on a peach-tree, offer good instances of spontaneous variations; but even in these cases, if we bear in mind the power of a minute drop of poison in producing complex galls, we ought not to feel too sure that the above variations are not the effect of some local change in the nature of the sap, due to some change in the conditions. There must be some efficient cause for each slight individual difference, as well as for more strongly marked variations which occasionally arise; and if the unknown cause were to act persistently, it is almost certain that all the individuals of the species would be similarly modified. In the earlier editions of this work I underrated, as it now seems probable, the frequency and importance of modifications due to spontaneous variability. But it is impossible to attribute to this cause the innumerable structures which are so well adapted to the habits of life of each species. I can no more believe in this than that the well-adapted form of a race-horse or greyhound, which before the principle of selection by man was well understood, excited so much surprise in the minds of the older naturalists, can thus be explained. It may be worth while to illustrate some of the foregoing remarks. With respect to the assumed inutility of various parts and organs, it is hardly necessary to observe that even in the higher and best-known animals many structures exist, which are so highly developed that no one doubts that they are of importance, yet their use has not been, or has only recently been, ascertained. As Bronn gives the length of the ears and tail in the several species of mice as instances, though trifling ones, of differences in structure which can be of no special use, I may mention that, according to Dr. Schobl, the external ears of the common mouse are supplied in an extraordinary manner with nerves, so that they no doubt serve as tactile organs; hence the length of the ears can hardly be quite unimportant. We shall, also, presently see that the tail is a highly useful prehensile organ to some of the species; and its use would be much influence by its length. With respect to plants, to which on account of Nageli's essay I shall confine myself in the following remarks, it will be admitted that the flowers of the orchids present a multitude of curious structures, which a few years ago would have been considered as mere morphological differences without any special function; but they are now known to be of the highest importance for the fertilisation of the species through the aid of insects, and have probably been gained through natural selection. No one until lately would have imagined that in dimorphic and trimorphic plants the different lengths of the stamens and pistils, and their arrangement, could have been of any service, but now we know this to be the case. In certain whole groups of plants the ovules stand erect, and in others they are suspended; and within the same ovarium of some few plants, one ovule holds the former and a second ovule the latter position. These positions seem at first purely morphological, or of no physiological signification; but Dr. Hooker informs me that within the same ovarium the upper ovules alone in some cases, and in others the lower ones alone are fertilised; and he suggests that this probably depends on the direction in which the pollen-tubes enter the ovarium. If so, the position of the ovules, even when one is erect and the other suspended within the same ovarium, would follow the selection of any slight deviations in position which favoured their fertilisation, and the production of seed. Several plants belonging to distinct orders habitually produce flowers of two kinds--the one open, of the ordinary structure, the other closed and imperfect. These two kinds of flowers sometimes differ wonderfully in structure, yet may be seen to graduate into each other on the same plant. The ordinary and open flowers can be intercrossed; and the benefits which certainly are derived from this process are thus secured. The closed and imperfect flowers are, however, manifestly of high importance, as they yield with the utmost safety a large stock of seed, with the expenditure of wonderfully little pollen. The two kinds of flowers often differ much, as just stated, in structure. The petals in the imperfect flowers almost always consist of mere rudiments, and the pollen-grains are reduced in diameter. In Ononis columnae five of the alternate stamens are rudimentary; and in some species of Viola three stamens are in this state, two retaining their proper function, but being of very small size. In six out of thirty of the closed flowers in an Indian violet (name unknown, for the plants have never produced with me perfect flowers), the sepals are reduced from the normal number of five to three. In one section of the Malpighiaceae the closed flowers, according to A. de Jussieu, are still further modified, for the five stamens which stand opposite to the sepals are all aborted, a sixth stamen standing opposite to a petal being alone developed; and this stamen is not present in the ordinary flowers of this species; the style is aborted; and the ovaria are reduced from three to two. Now although natural selection may well have had the power to prevent some of the flowers from expanding, and to reduce the amount of pollen, when rendered by the closure of the flowers superfluous, yet hardly any of the above special modifications can have been thus determined, but must have followed from the laws of growth, including the functional inactivity of parts, during the progress of the reduction of the pollen and the closure of the flowers. It is so necessary to appreciate the important effects of the laws of growth, that I will give some additional cases of another kind, namely of differences in the same part or organ, due to differences in relative position on the same plant. In the Spanish chestnut, and in certain fir-trees, the angles of divergence of the leaves differ, according to Schacht, in the nearly horizontal and in the upright branches. In the common rue and some other plants, one flower, usually the central or terminal one, opens first, and has five sepals and petals, and five divisions to the ovarium; while all the other flowers on the plant are tetramerous. In the British Adoxa the uppermost flower generally has two calyx-lobes with the other organs tetramerous, while the surrounding flowers generally have three calyx-lobes with the other organs pentamerous. In many Compositae and Umbelliferae (and in some other plants) the circumferential flowers have their corollas much more developed than those of the centre; and this seems often connected with the abortion of the reproductive organs. It is a more curious fact, previously referred to, that the achenes or seeds of the circumference and centre sometimes differ greatly in form, colour and other characters. In Carthamus and some other Compositae the central achenes alone are furnished with a pappus; and in Hyoseris the same head yields achenes of three different forms. In certain Umbelliferae the exterior seeds, according to Tausch, are orthospermous, and the central one coelospermous, and this is a character which was considered by De Candolle to be in other species of the highest systematic importance. Professor Braun mentions a Fumariaceous genus, in which the flowers in the lower part of the spike bear oval, ribbed, one-seeded nutlets; and in the upper part of the spike, lanceolate, two-valved and two-seeded siliques. In these several cases, with the exception of that of the well-developed ray-florets, which are of service in making the flowers conspicuous to insects, natural selection cannot, as far as we can judge, have come into play, or only in a quite subordinate manner. All these modifications follow from the relative position and inter-action of the parts; and it can hardly be doubted that if all the flowers and leaves on the same plant had been subjected to the same external and internal condition, as are the flowers and leaves in certain positions, all would have been modified in the same manner. In numerous other cases we find modifications of structure, which are considered by botanists to be generally of a highly important nature, affecting only some of the flowers on the same plant, or occurring on distinct plants, which grow close together under the same conditions. As these variations seem of no special use to the plants, they cannot have been influenced by natural selection. Of their cause we are quite ignorant; we cannot even attribute them, as in the last class of cases, to any proximate agency, such as relative position. I will give only a few instances. It is so common to observe on the same plant, flowers indifferently tetramerous, pentamerous, etc., that I need not give examples; but as numerical variations are comparatively rare when the parts are few, I may mention that, according to De Candolle, the flowers of Papaver bracteatum offer either two sepals with four petals (which is the common type with poppies), or three sepals with six petals. The manner in which the petals are folded in the bud is in most groups a very constant morphological character; but Professor Asa Gray states that with some species of Mimulus, the aestivation is almost as frequently that of the Rhinanthideae as of the Antirrhinideae, to which latter tribe the genus belongs. Aug. St. Hilaire gives the following cases: the genus Zanthoxylon belongs to a division of the Rutaceae with a single ovary, but in some species flowers may be found on the same plant, and even in the same panicle, with either one or two ovaries. In Helianthemum the capsule has been described as unilocular or tri-locular; and in H. mutabile, "Une lame PLUS OU MOINS LARGE, s'etend entre le pericarpe et le placenta." In the flowers of Saponaria officinalis Dr. Masters has observed instances of both marginal and free central placentation. Lastly, St. Hilaire found towards the southern extreme of the range of Gomphia oleaeformis two forms which he did not at first doubt were distinct species, but he subsequently saw them growing on the same bush; and he then adds, "Voila donc dans un meme individu des loges et un style qui se rattachent tantot a un axe verticale et tantot a un gynobase." We thus see that with plants many morphological changes may be attributed to the laws of growth and the inter-action of parts, independently of natural selection. But with respect to Nageli's doctrine of an innate tendency towards perfection or progressive development, can it be said in the case of these strongly pronounced variations, that the plants have been caught in the act of progressing towards a higher state of development? On the contrary, I should infer from the mere fact of the parts in question differing or varying greatly on the same plant, that such modifications were of extremely small importance to the plants themselves, of whatever importance they may generally be to us for our classifications. The acquisition of a useless part can hardly be said to raise an organism in the natural scale; and in the case of the imperfect, closed flowers, above described, if any new principle has to be invoked, it must be one of retrogression rather than of progression; and so it must be with many parasitic and degraded animals. We are ignorant of the exciting cause of the above specified modifications; but if the unknown cause were to act almost uniformly for a length of time, we may infer that the result would be almost uniform; and in this case all the individuals of the species would be modified in the same manner. From the fact of the above characters being unimportant for the welfare of the species, any slight variations which occurred in them would not have been accumulated and augmented through natural selection. A structure which has been developed through long-continued selection, when it ceases to be of service to a species, generally becomes variable, as we see with rudimentary organs; for it will no longer be regulated by this same power of selection. But when, from the nature of the organism and of the conditions, modifications have been induced which are unimportant for the welfare of the species, they may be, and apparently often have been, transmitted in nearly the same state to numerous, otherwise modified, descendants. It cannot have been of much importance to the greater number of mammals, birds, or reptiles, whether they were clothed with hair, feathers or scales; yet hair has been transmitted to almost all mammals, feathers to all birds, and scales to all true reptiles. A structure, whatever it may be, which is common to many allied forms, is ranked by us as of high systematic importance, and consequently is often assumed to be of high vital importance to the species. Thus, as I am inclined to believe, morphological differences, which we consider as important--such as the arrangement of the leaves, the divisions of the flower or of the ovarium, the position of the ovules, etc., first appeared in many cases as fluctuating variations, which sooner or later became constant through the nature of the organism and of the surrounding conditions, as well as through the intercrossing of distinct individuals, but not through natural selection; for as these morphological characters do not affect the welfare of the species, any slight deviations in them could not have been governed or accumulated through this latter agency. It is a strange result which we thus arrive at, namely, that characters of slight vital importance to the species, are the most important to the systematist; but, as we shall hereafter see when we treat of the genetic principle of classification, this is by no means so paradoxical as it may at first appear. Although we have no good evidence of the existence in organic beings of an innate tendency towards progressive development, yet this necessarily follows, as I have attempted to show in the fourth chapter, through the continued action of natural selection. For the best definition which has ever been given of a high standard of organisation, is the degree to which the parts have been specialised or differentiated; and natural selection tends towards this end, inasmuch as the parts are thus enabled to perform their functions more efficiently. A distinguished zoologist, Mr. St. George Mivart, has recently collected all the objections which have ever been advanced by myself and others against the theory of natural selection, as propounded by Mr. Wallace and myself, and has illustrated them with admirable art and force. When thus marshalled, they make a formidable array; and as it forms no part of Mr. Mivart's plan to give the various facts and considerations opposed to his conclusions, no slight effort of reason and memory is left to the reader, who may wish to weigh the evidence on both sides. When discussing special cases, Mr. Mivart passes over the effects of the increased use and disuse of parts, which I have always maintained to be highly important, and have treated in my "Variation under Domestication" at greater length than, as I believe, any other writer. He likewise often assumes that I attribute nothing to variation, independently of natural selection, whereas in the work just referred to I have collected a greater number of well-established cases than can be found in any other work known to me. My judgment may not be trustworthy, but after reading with care Mr. Mivart's book, and comparing each section with what I have said on the same head, I never before felt so strongly convinced of the general truth of the conclusions here arrived at, subject, of course, in so intricate a subject, to much partial error. All Mr. Mivart's objections will be, or have been, considered in the present volume. The one new point which appears to have struck many readers is, "That natural selection is incompetent to account for the incipient stages of useful structures." This subject is intimately connected with that of the gradation of the characters, often accompanied by a change of function, for instance, the conversion of a swim-bladder into lungs, points which were discussed in the last chapter under two headings. Nevertheless, I will here consider in some detail several of the cases advanced by Mr. Mivart, selecting those which are the most illustrative, as want of space prevents me from considering all. The giraffe, by its lofty stature, much elongated neck, fore legs, head and tongue, has its whole frame beautifully adapted for browsing on the higher branches of trees. It can thus obtain food beyond the reach of the other Ungulata or hoofed animals inhabiting the same country; and this must be a great advantage to it during dearths. The Niata cattle in South America show us how small a difference in structure may make, during such periods, a great difference in preserving an animal's life. These cattle can browse as well as others on grass, but from the projection of the lower jaw they cannot, during the often recurrent droughts, browse on the twigs of trees, reeds, etc., to which food the common cattle and horses are then driven; so that at these times the Niatas perish, if not fed by their owners. Before coming to Mr. Mivart's objections, it may be well to explain once again how natural selection will act in all ordinary cases. Man has modified some of his animals, without necessarily having attended to special points of structure, by simply preserving and breeding from the fleetest individuals, as with the race-horse and greyhound, or as with the game-cock, by breeding from the victorious birds. So under nature with the nascent giraffe, the individuals which were the highest browsers and were able during dearths to reach even an inch or two above the others, will often have been preserved; for they will have roamed over the whole country in search of food. That the individuals of the same species often differ slightly in the relative lengths of all their parts may be seen in many works of natural history, in which careful measurements are given. These slight proportional differences, due to the laws of growth and variation, are not of the slightest use or importance to most species. But it will have been otherwise with the nascent giraffe, considering its probable habits of life; for those individuals which had some one part or several parts of their bodies rather more elongated than usual, would generally have survived. These will have intercrossed and left offspring, either inheriting the same bodily peculiarities, or with a tendency to vary again in the same manner; while the individuals less favoured in the same respects will have been the most liable to perish. We here see that there is no need to separate single pairs, as man does, when he methodically improves a breed: natural selection will preserve and thus separate all the superior individuals, allowing them freely to intercross, and will destroy all the inferior individuals. By this process long-continued, which exactly corresponds with what I have called unconscious selection by man, combined, no doubt, in a most important manner with the inherited effects of the increased use of parts, it seems to me almost certain that an ordinary hoofed quadruped might be converted into a giraffe. To this conclusion Mr. Mivart brings forward two objections. One is that the increased size of the body would obviously require an increased supply of food, and he considers it as "very problematical whether the disadvantages thence arising would not, in times of scarcity, more than counterbalance the advantages." But as the giraffe does actually exist in large numbers in Africa, and as some of the largest antelopes in the world, taller than an ox, abound there, why should we doubt that, as far as size is concerned, intermediate gradations could formerly have existed there, subjected as now to severe dearths. Assuredly the being able to reach, at each stage of increased size, to a supply of food, left untouched by the other hoofed quadrupeds of the country, would have been of some advantage to the nascent giraffe. Nor must we overlook the fact, that increased bulk would act as a protection against almost all beasts of prey excepting the lion; and against this animal, its tall neck--and the taller the better--would, as Mr. Chauncey Wright has remarked, serve as a watch-tower. It is from this cause, as Sir S. Baker remarks, that no animal is more difficult to stalk than the giraffe. This animal also uses its long neck as a means of offence or defence, by violently swinging its head armed with stump-like horns. The preservation of each species can rarely be determined by any one advantage, but by the union of all, great and small. Mr. Mivart then asks (and this is his second objection), if natural selection be so potent, and if high browsing be so great an advantage, why has not any other hoofed quadruped acquired a long neck and lofty stature, besides the giraffe, and, in a lesser degree, the camel, guanaco and macrauchenia? Or, again, why has not any member of the group acquired a long proboscis? With respect to South Africa, which was formerly inhabited by numerous herds of the giraffe, the answer is not difficult, and can best be given by an illustration. In every meadow in England, in which trees grow, we see the lower branches trimmed or planed to an exact level by the browsing of the horses or cattle; and what advantage would it be, for instance, to sheep, if kept there, to acquire slightly longer necks? In every district some one kind of animal will almost certainly be able to browse higher than the others; and it is almost equally certain that this one kind alone could have its neck elongated for this purpose, through natural selection and the effects of increased use. In South Africa the competition for browsing on the higher branches of the acacias and other trees must be between giraffe and giraffe, and not with the other ungulate animals. Why, in other quarters of the world, various animals belonging to this same order have not acquired either an elongated neck or a proboscis, cannot be distinctly answered; but it is as unreasonable to expect a distinct answer to such a question as why some event in the history of mankind did not occur in one country while it did in another. We are ignorant with respect to the conditions which determine the numbers and range of each species, and we cannot even conjecture what changes of structure would be favourable to its increase in some new country. We can, however, see in a general manner that various causes might have interfered with the development of a long neck or proboscis. To reach the foliage at a considerable height (without climbing, for which hoofed animals are singularly ill-constructed) implies greatly increased bulk of body; and we know that some areas support singularly few large quadrupeds, for instance South America, though it is so luxuriant, while South Africa abounds with them to an unparalleled degree. Why this should be so we do not know; nor why the later tertiary periods should have been much more favourable for their existence than the present time. Whatever the causes may have been, we can see that certain districts and times would have been much more favourable than others for the development of so large a quadruped as the giraffe. In order that an animal should acquire some structure specially and largely developed, it is almost indispensable that several other parts should be modified and coadapted. Although every part of the body varies slightly, it does not follow that the necessary parts should always vary in the right direction and to the right degree. With the different species of our domesticated animals we know that the parts vary in a different manner and degree, and that some species are much more variable than others. Even if the fitting variations did arise, it does not follow that natural selection would be able to act on them and produce a structure which apparently would be beneficial to the species. For instance, if the number of individuals existing in a country is determined chiefly through destruction by beasts of prey--by external or internal parasites, etc.--as seems often to be the case, then natural selection will be able to do little, or will be greatly retarded, in modifying any particular structure for obtaining food. Lastly, natural selection is a slow process, and the same favourable conditions must long endure in order that any marked effect should thus be produced. Except by assigning such general and vague reasons, we cannot explain why, in many quarters of the world, hoofed quadrupeds have not acquired much elongated necks or other means for browsing on the higher branches of trees. Objections of the same nature as the foregoing have been advanced by many writers. In each case various causes, besides the general ones just indicated, have probably interfered with the acquisition through natural selection of structures, which it is thought would be beneficial to certain species. One writer asks, why has not the ostrich acquired the power of flight? But a moment's reflection will show what an enormous supply of food would be necessary to give to this bird of the desert force to move its huge body through the air. Oceanic islands are inhabited by bats and seals, but by no terrestrial mammals; yet as some of these bats are peculiar species, they must have long inhabited their present homes. Therefore Sir C. Lyell asks, and assigns certain reasons in answer, why have not seals and bats given birth on such islands to forms fitted to live on the land? But seals would necessarily be first converted into terrestrial carnivorous animals of considerable size, and bats into terrestrial insectivorous animals; for the former there would be no prey; for the bats ground-insects would serve as food, but these would already be largely preyed on by the reptiles or birds, which first colonise and abound on most oceanic islands. Gradations of structure, with each stage beneficial to a changing species, will be favoured only under certain peculiar conditions. A strictly terrestrial animal, by occasionally hunting for food in shallow water, then in streams or lakes, might at last be converted into an animal so thoroughly aquatic as to brave the open ocean. But seals would not find on oceanic islands the conditions favourable to their gradual reconversion into a terrestrial form. Bats, as formerly shown, probably acquired their wings by at first gliding through the air from tree to tree, like the so-called flying squirrels, for the sake of escaping from their enemies, or for avoiding falls; but when the power of true flight had once been acquired, it would never be reconverted back, at least for the above purposes, into the less efficient power of gliding through the air. Bats, might, indeed, like many birds, have had their wings greatly reduced in size, or completely lost, through disuse; but in this case it would be necessary that they should first have acquired the power of running quickly on the ground, by the aid of their hind legs alone, so as to compete with birds or other ground animals; and for such a change a bat seems singularly ill-fitted. These conjectural remarks have been made merely to show that a transition of structure, with each step beneficial, is a highly complex affair; and that there is nothing strange in a transition not having occurred in any particular case. Lastly, more than one writer has asked why have some animals had their mental powers more highly developed than others, as such development would be advantageous to all? Why have not apes acquired the intellectual powers of man? Various causes could be assigned; but as they are conjectural, and their relative probability cannot be weighed, it would be useless to give them. A definite answer to the latter question ought not to be expected, seeing that no one can solve the simpler problem, why, of two races of savages, one has risen higher in the scale of civilisation than the other; and this apparently implies increased brain power. We will return to Mr. Mivart's other objections. Insects often resemble for the sake of protection various objects, such as green or decayed leaves, dead twigs, bits of lichen, flowers, spines, excrement of birds, and living insects; but to this latter point I shall hereafter recur. The resemblance is often wonderfully close, and is not confined to colour, but extends to form, and even to the manner in which the insects hold themselves. The caterpillars which project motionless like dead twigs from the bushes on which they feed, offer an excellent instance of a resemblance of this kind. The cases of the imitation of such objects as the excrement of birds, are rare and exceptional. On this head, Mr. Mivart remarks, "As, according to Mr. Darwin's theory, there is a constant tendency to indefinite variation, and as the minute incipient variations will be in ALL DIRECTIONS, they must tend to neutralize each other, and at first to form such unstable modifications that it is difficult, if not impossible, to see how such indefinite oscillations of infinitesimal beginnings can ever build up a sufficiently appreciable resemblance to a leaf, bamboo, or other object, for natural selection to seize upon and perpetuate." But in all the foregoing cases the insects in their original state no doubt presented some rude and accidental resemblance to an object commonly found in the stations frequented by them. Nor is this at all improbable, considering the almost infinite number of surrounding objects and the diversity in form and colour of the hosts of insects which exist. As some rude resemblance is necessary for the first start, we can understand how it is that the larger and higher animals do not (with the exception, as far as I know, of one fish) resemble for the sake of protection special objects, but only the surface which commonly surrounds them, and this chiefly in colour. Assuming that an insect originally happened to resemble in some degree a dead twig or a decayed leaf, and that it varied slightly in many ways, then all the variations which rendered the insect at all more like any such object, and thus favoured its escape, would be preserved, while other variations would be neglected and ultimately lost; or, if they rendered the insect at all less like the imitated object, they would be eliminated. There would indeed be force in Mr. Mivart's objection, if we were to attempt to account for the above resemblances, independently of natural selection, through mere fluctuating variability; but as the case stands there is none. Nor can I see any force in Mr. Mivart's difficulty with respect to "the last touches of perfection in the mimicry;" as in the case given by Mr. Wallace, of a walking-stick insect (Ceroxylus laceratus), which resembles "a stick grown over by a creeping moss or jungermannia." So close was this resemblance, that a native Dyak maintained that the foliaceous excrescences were really moss. Insects are preyed on by birds and other enemies whose sight is probably sharper than ours, and every grade in resemblance which aided an insect to escape notice or detection, would tend towards its preservation; and the more perfect the resemblance so much the better for the insect. Considering the nature of the differences between the species in the group which includes the above Ceroxylus, there is nothing improbable in this insect having varied in the irregularities on its surface, and in these having become more or less green-coloured; for in every group the characters which differ in the several species are the most apt to vary, while the generic characters, or those common to all the species, are the most constant. The Greenland whale is one of the most wonderful animals in the world, and the baleen, or whalebone, one of its greatest peculiarities. The baleen consists of a row, on each side of the upper jaw, of about 300 plates or laminae, which stand close together transversely to the longer axis of the mouth. Within the main row there are some subsidiary rows. The extremities and inner margins of all the plates are frayed into stiff bristles, which clothe the whole gigantic palate, and serve to strain or sift the water, and thus to secure the minute prey on which these great animals subsist. The middle and longest lamina in the Greenland whale is ten, twelve, or even fifteen feet in length; but in the different species of Cetaceans there are gradations in length; the middle lamina being in one species, according to Scoresby, four feet, in another three, in another eighteen inches, and in the Balaenoptera rostrata only about nine inches in length. The quality of the whalebone also differs in the different species. With respect to the baleen, Mr. Mivart remarks that if it "had once attained such a size and development as to be at all useful, then its preservation and augmentation within serviceable limits would be promoted by natural selection alone. But how to obtain the beginning of such useful development?" In answer, it may be asked, why should not the early progenitors of the whales with baleen have possessed a mouth constructed something like the lamellated beak of a duck? Ducks, like whales, subsist by sifting the mud and water; and the family has sometimes been called Criblatores, or sifters. I hope that I may not be misconstrued into saying that the progenitors of whales did actually possess mouths lamellated like the beak of a duck. I wish only to show that this is not incredible, and that the immense plates of baleen in the Greenland whale might have been developed from such lamellae by finely graduated steps, each of service to its possessor. The beak of a shoveller-duck (Spatula clypeata) is a more beautiful and complex structure than the mouth of a whale. The upper mandible is furnished on each side (in the specimen examined by me) with a row or comb formed of 188 thin, elastic lamellae, obliquely bevelled so as to be pointed, and placed transversely to the longer axis of the mouth. They arise from the palate, and are attached by flexible membrane to the sides of the mandible. Those standing towards the middle are the longest, being about one-third of an inch in length, and they project fourteen one-hundredths of an inch beneath the edge. At their bases there is a short subsidiary row of obliquely transverse lamellae. In these several respects they resemble the plates of baleen in the mouth of a whale. But towards the extremity of the beak they differ much, as they project inward, instead of straight downward. The entire head of the shoveller, though incomparably less bulky, is about one-eighteenth of the length of the head of a moderately large Balaenoptera rostrata, in which species the baleen is only nine inches long; so that if we were to make the head of the shoveller as long as that of the Balaenoptera, the lamellae would be six inches in length, that is, two-thirds of the length of the baleen in this species of whale. The lower mandible of the shoveller-duck is furnished with lamellae of equal length with these above, but finer; and in being thus furnished it differs conspicuously from the lower jaw of a whale, which is destitute of baleen. On the other hand, the extremities of these lower lamellae are frayed into fine bristly points, so that they thus curiously resemble the plates of baleen. In the genus Prion, a member of the distinct family of the Petrels, the upper mandible alone is furnished with lamellae, which are well developed and project beneath the margin; so that the beak of this bird resembles in this respect the mouth of a whale. From the highly developed structure of the shoveller's beak we may proceed (as I have learned from information and specimens sent to me by Mr. Salvin), without any great break, as far as fitness for sifting is concerned, through the beak of the Merganetta armata, and in some respects through that of the Aix sponsa, to the beak of the common duck. In this latter species the lamellae are much coarser than in the shoveller, and are firmly attached to the sides of the mandible; they are only about fifty in number on each side, and do not project at all beneath the margin. They are square-topped, and are edged with translucent, hardish tissue, as if for crushing food. The edges of the lower mandible are crossed by numerous fine ridges, which project very little. Although the beak is thus very inferior as a sifter to that of a shoveller, yet this bird, as every one knows, constantly uses it for this purpose. There are other species, as I hear from Mr. Salvin, in which the lamellae are considerably less developed than in the common duck; but I do not know whether they use their beaks for sifting the water. Turning to another group of the same family. In the Egyptian goose (Chenalopex) the beak closely resembles that of the common duck; but the lamellae are not so numerous, nor so distinct from each other, nor do they project so much inward; yet this goose, as I am informed by Mr. E. Bartlett, "uses its bill like a duck by throwing the water out at the corners." Its chief food, however, is grass, which it crops like the common goose. In this latter bird the lamellae of the upper mandible are much coarser than in the common duck, almost confluent, about twenty-seven in number on each side, and terminating upward in teeth-like knobs. The palate is also covered with hard rounded knobs. The edges of the lower mandible are serrated with teeth much more prominent, coarser and sharper than in the duck. The common goose does not sift the water, but uses its beak exclusively for tearing or cutting herbage, for which purpose it is so well fitted that it can crop grass closer than almost any other animal. There are other species of geese, as I hear from Mr. Bartlett, in which the lamellae are less developed than in the common goose. We thus see that a member of the duck family, with a beak constructed like that of a common goose and adapted solely for grazing, or even a member with a beak having less well-developed lamellae, might be converted by small changes into a species like the Egyptian goose--this into one like the common duck--and, lastly, into one like the shoveller, provided with a beak almost exclusively adapted for sifting the water; for this bird could hardly use any part of its beak, except the hooked tip, for seizing or tearing solid food. The beak of a goose, as I may add, might also be converted by small changes into one provided with prominent, recurved teeth, like those of the Merganser (a member of the same family), serving for the widely different purpose of securing live fish. Returning to the whales. The Hyperoodon bidens is destitute of true teeth in an efficient condition, but its palate is roughened, according to Lacepede, with small unequal, hard points of horn. There is, therefore, nothing improbable in supposing that some early Cetacean form was provided with similar points of horn on the palate, but rather more regularly placed, and which, like the knobs on the beak of the goose, aided it in seizing or tearing its food. If so, it will hardly be denied that the points might have been converted through variation and natural selection into lamellae as well-developed as those of the Egyptian goose, in which case they would have been used both for seizing objects and for sifting the water; then into lamellae like those of the domestic duck; and so onward, until they became as well constructed as those of the shoveller, in which case they would have served exclusively as a sifting apparatus. From this stage, in which the lamellae would be two-thirds of the length of the plates of baleen in the Balaenoptera rostrata, gradations, which may be observed in still-existing Cetaceans, lead us onward to the enormous plates of baleen in the Greenland whale. Nor is there the least reason to doubt that each step in this scale might have been as serviceable to certain ancient Cetaceans, with the functions of the parts slowly changing during the progress of development, as are the gradations in the beaks of the different existing members of the duck-family. We should bear in mind that each species of duck is subjected to a severe struggle for existence, and that the structure of every part of its frame must be well adapted to its conditions of life. The Pleuronectidae, or Flat-fish, are remarkable for their asymmetrical bodies. They rest on one side--in the greater number of species on the left, but in some on the right side; and occasionally reversed adult specimens occur. The lower, or resting-surface, resembles at first sight the ventral surface of an ordinary fish; it is of a white colour, less developed in many ways than the upper side, with the lateral fins often of smaller size. But the eyes offer the most remarkable peculiarity; for they are both placed on the upper side of the head. During early youth, however, they stand opposite to each other, and the whole body is then symmetrical, with both sides equally coloured. Soon the eye proper to the lower side begins to glide slowly round the head to the upper side; but does not pass right through the skull, as was formerly thought to be the case. It is obvious that unless the lower eye did thus travel round, it could not be used by the fish while lying in its habitual position on one side. The lower eye would, also, have been liable to be abraded by the sandy bottom. That the Pleuronectidae are admirably adapted by their flattened and asymmetrical structure for their habits of life, is manifest from several species, such as soles, flounders, etc., being extremely common. The chief advantages thus gained seem to be protection from their enemies, and facility for feeding on the ground. The different members, however, of the family present, as Schiodte remarks, "a long series of forms exhibiting a gradual transition from Hippoglossus pinguis, which does not in any considerable degree alter the shape in which it leaves the ovum, to the soles, which are entirely thrown to one side." Mr. Mivart has taken up this case, and remarks that a sudden spontaneous transformation in the position of the eyes is hardly conceivable, in which I quite agree with him. He then adds: "If the transit was gradual, then how such transit of one eye a minute fraction of the journey towards the other side of the head could benefit the individual is, indeed, far from clear. It seems, even, that such an incipient transformation must rather have been injurious." But he might have found an answer to this objection in the excellent observations published in 1867 by Malm. The Pleuronectidae, while very young and still symmetrical, with their eyes standing on opposite sides of the head, cannot long retain a vertical position, owing to the excessive depth of their bodies, the small size of their lateral fins, and to their being destitute of a swim-bladder. Hence, soon growing tired, they fall to the bottom on one side. While thus at rest they often twist, as Malm observed, the lower eye upward, to see above them; and they do this so vigorously that the eye is pressed hard against the upper part of the orbit. The forehead between the eyes consequently becomes, as could be plainly seen, temporarily contracted in breadth. On one occasion Malm saw a young fish raise and depress the lower eye through an angular distance of about seventy degrees. We should remember that the skull at this early age is cartilaginous and flexible, so that it readily yields to muscular action. It is also known with the higher animals, even after early youth, that the skull yields and is altered in shape, if the skin or muscles be permanently contracted through disease or some accident. With long-eared rabbits, if one ear flops forward and downward, its weight drags forward all the bones of the skull on the same side, of which I have given a figure. Malm states that the newly-hatched young of perches, salmon, and several other symmetrical fishes, have the habit of occasionally resting on one side at the bottom; and he has observed that they often then strain their lower eyes so as to look upward; and their skulls are thus rendered rather crooked. These fishes, however, are soon able to hold themselves in a vertical position, and no permanent effect is thus produced. With the Pleuronectidae, on the other hand, the older they grow the more habitually they rest on one side, owing to the increasing flatness of their bodies, and a permanent effect is thus produced on the form of the head, and on the position of the eyes. Judging from analogy, the tendency to distortion would no doubt be increased through the principle of inheritance. Schiodte believes, in opposition to some other naturalists, that the Pleuronectidae are not quite symmetrical even in the embryo; and if this be so, we could understand how it is that certain species, while young, habitually fall over and rest on the left side, and other species on the right side. Malm adds, in confirmation of the above view, that the adult Trachypterus arcticus, which is not a member of the Pleuronectidae, rests on its left side at the bottom, and swims diagonally through the water; and in this fish, the two sides of the head are said to be somewhat dissimilar. Our great authority on Fishes, Dr. Gunther, concludes his abstract of Malm's paper, by remarking that "the author gives a very simple explanation of the abnormal condition of the Pleuronectoids." We thus see that the first stages of the transit of the eye from one side of the head to the other, which Mr. Mivart considers would be injurious, may be attributed to the habit, no doubt beneficial to the individual and to the species, of endeavouring to look upward with both eyes, while resting on one side at the bottom. We may also attribute to the inherited effects of use the fact of the mouth in several kinds of flat-fish being bent towards the lower surface, with the jaw bones stronger and more effective on this, the eyeless side of the head, than on the other, for the sake, as Dr. Traquair supposes, of feeding with ease on the ground. Disuse, on the other hand, will account for the less developed condition of the whole inferior half of the body, including the lateral fins; though Yarrel thinks that the reduced size of these fins is advantageous to the fish, as "there is so much less room for their action than with the larger fins above." Perhaps the lesser number of teeth in the proportion of four to seven in the upper halves of the two jaws of the plaice, to twenty-five to thirty in the lower halves, may likewise be accounted for by disuse. From the colourless state of the ventral surface of most fishes and of many other animals, we may reasonably suppose that the absence of colour in flat-fish on the side, whether it be the right or left, which is under-most, is due to the exclusion of light. But it cannot be supposed that the peculiar speckled appearance of the upper side of the sole, so like the sandy bed of the sea, or the power in some species, as recently shown by Pouchet, of changing their colour in accordance with the surrounding surface, or the presence of bony tubercles on the upper side of the turbot, are due to the action of the light. Here natural selection has probably come into play, as well as in adapting the general shape of the body of these fishes, and many other peculiarities, to their habits of life. We should keep in mind, as I have before insisted, that the inherited effects of the increased use of parts, and perhaps of their disuse, will be strengthened by natural selection. For all spontaneous variations in the right direction will thus be preserved; as will those individuals which inherit in the highest degree the effects of the increased and beneficial use of any part. How much to attribute in each particular case to the effects of use, and how much to natural selection, it seems impossible to decide. I may give another instance of a structure which apparently owes its origin exclusively to use or habit. The extremity of the tail in some American monkeys has been converted into a wonderfully perfect prehensile organ, and serves as a fifth hand. A reviewer, who agrees with Mr. Mivart in every detail, remarks on this structure: "It is impossible to believe that in any number of ages the first slight incipient tendency to grasp could preserve the lives of the individuals possessing it, or favour their chance of having and of rearing offspring." But there is no necessity for any such belief. Habit, and this almost implies that some benefit great or small is thus derived, would in all probability suffice for the work. Brehm saw the young of an African monkey (Cercopithecus) clinging to the under surface of their mother by their hands, and at the same time they hooked their little tails round that of their mother. Professor Henslow kept in confinement some harvest mice (Mus messorius) which do not possess a structurally prehensive tail; but he frequently observed that they curled their tails round the branches of a bush placed in the cage, and thus aided themselves in climbing. I have received an analogous account from Dr. Gunther, who has seen a mouse thus suspend itself. If the harvest mouse had been more strictly arboreal, it would perhaps have had its tail rendered structurally prehensile, as is the case with some members of the same order. Why Cercopithecus, considering its habits while young, has not become thus provided, it would be difficult to say. It is, however, possible that the long tail of this monkey may be of more service to it as a balancing organ in making its prodigious leaps, than as a prehensile organ. The mammary glands are common to the whole class of mammals, and are indispensable for their existence; they must, therefore, have been developed at an extremely remote period, and we can know nothing positively about their manner of development. Mr. Mivart asks: "Is it conceivable that the young of any animal was ever saved from destruction by accidentally sucking a drop of scarcely nutritious fluid from an accidentally hypertrophied cutaneous gland of its mother? And even if one was so, what chance was there of the perpetuation of such a variation?" But the case is not here put fairly. It is admitted by most evolutionists that mammals are descended from a marsupial form; and if so, the mammary glands will have been at first developed within the marsupial sack. In the case of the fish (Hippocampus) the eggs are hatched, and the young are reared for a time, within a sack of this nature; and an American naturalist, Mr. Lockwood, believes from what he has seen of the development of the young, that they are nourished by a secretion from the cutaneous glands of the sack. Now, with the early progenitors of mammals, almost before they deserved to be thus designated, is it not at least possible that the young might have been similarly nourished? And in this case, the individuals which secreted a fluid, in some degree or manner the most nutritious, so as to partake of the nature of milk, would in the long run have reared a larger number of well-nourished offspring, than would the individuals which secreted a poorer fluid; and thus the cutaneous glands, which are the homologues of the mammary glands, would have been improved or rendered more effective. It accords with the widely extended principle of specialisation, that the glands over a certain space of the sack should have become more highly developed than the remainder; and they would then have formed a breast, but at first without a nipple, as we see in the Ornithorhyncus, at the base of the mammalian series. Through what agency the glands over a certain space became more highly specialised than the others, I will not pretend to decide, whether in part through compensation of growth, the effects of use, or of natural selection. The development of the mammary glands would have been of no service, and could not have been affected through natural selection, unless the young at the same time were able to partake of the secretion. There is no greater difficulty in understanding how young mammals have instinctively learned to suck the breast, than in understanding how unhatched chickens have learned to break the egg-shell by tapping against it with their specially adapted beaks; or how a few hours after leaving the shell they have learned to pick up grains of food. In such cases the most probable solution seems to be, that the habit was at first acquired by practice at a more advanced age, and afterwards transmitted to the offspring at an earlier age. But the young kangaroo is said not to suck, only to cling to the nipple of its mother, who has the power of injecting milk into the mouth of her helpless, half-formed offspring. On this head Mr. Mivart remarks: "Did no special provision exist, the young one must infallibly be choked by the intrusion of the milk into the wind-pipe. But there IS a special provision. The larynx is so elongated that it rises up into the posterior end of the nasal passage, and is thus enabled to give free entrance to the air for the lungs, while the milk passes harmlessly on each side of this elongated larynx, and so safely attains the gullet behind it." Mr. Mivart then asks how did natural selection remove in the adult kangaroo (and in most other mammals, on the assumption that they are descended from a marsupial form), "this at least perfectly innocent and harmless structure?" It may be suggested in answer that the voice, which is certainly of high importance to many animals, could hardly have been used with full force as long as the larynx entered the nasal passage; and Professor Flower has suggested to me that this structure would have greatly interfered with an animal swallowing solid food. We will now turn for a short space to the lower divisions of the animal kingdom. The Echinodermata (star-fishes, sea-urchins, etc.) are furnished with remarkable organs, called pedicellariae, which consist, when well developed, of a tridactyle forceps--that is, of one formed of three serrated arms, neatly fitting together and placed on the summit of a flexible stem, moved by muscles. These forceps can seize firmly hold of any object; and Alexander Agassiz has seen an Echinus or sea-urchin rapidly passing particles of excrement from forceps to forceps down certain lines of its body, in order that its shell should not be fouled. But there is no doubt that besides removing dirt of all kinds, they subserve other functions; and one of these apparently is defence. With respect to these organs, Mr. Mivart, as on so many previous occasions, asks: "What would be the utility of the FIRST RUDIMENTARY BEGINNINGS of such structures, and how could such insipient buddings have ever preserved the life of a single Echinus?" He adds, "not even the SUDDEN development of the snapping action would have been beneficial without the freely movable stalk, nor could the latter have been efficient without the snapping jaws, yet no minute, nearly indefinite variations could simultaneously evolve these complex co-ordinations of structure; to deny this seems to do no less than to affirm a startling paradox." Paradoxical as this may appear to Mr. Mivart, tridactyle forcepses, immovably fixed at the base, but capable of a snapping action, certainly exist on some star-fishes; and this is intelligible if they serve, at least in part, as a means of defence. Mr. Agassiz, to whose great kindness I am indebted for much information on the subject, informs me that there are other star-fishes, in which one of the three arms of the forceps is reduced to a support for the other two; and again, other genera in which the third arm is completely lost. In Echinoneus, the shell is described by M. Perrier as bearing two kinds of pedicellariae, one resembling those of Echinus, and the other those of Spatangus; and such cases are always interesting as affording the means of apparently sudden transitions, through the abortion of one of the two states of an organ. With respect to the steps by which these curious organs have been evolved, Mr. Agassiz infers from his own researches and those of Mr. Muller, that both in star-fishes and sea-urchins the pedicellariae must undoubtedly be looked at as modified spines. This may be inferred from their manner of development in the individual, as well as from a long and perfect series of gradations in different species and genera, from simple granules to ordinary spines, to perfect tridactyle pedicellariae. The gradation extends even to the manner in which ordinary spines and the pedicellariae, with their supporting calcareous rods, are articulated to the shell. In certain genera of star-fishes, "the very combinations needed to show that the pedicellariae are only modified branching spines" may be found. Thus we have fixed spines, with three equi-distant, serrated, movable branches, articulated to near their bases; and higher up, on the same spine, three other movable branches. Now when the latter arise from the summit of a spine they form, in fact, a rude tridactyle pedicellariae, and such may be seen on the same spine together with the three lower branches. In this case the identity in nature between the arms of the pedicellariae and the movable branches of a spine, is unmistakable. It is generally admitted that the ordinary spines serve as a protection; and if so, there can be no reason to doubt that those furnished with serrated and movable branches likewise serve for the same purpose; and they would thus serve still more effectively as soon as by meeting together they acted as a prehensile or snapping apparatus. Thus every gradation, from an ordinary fixed spine to a fixed pedicellariae, would be of service. In certain genera of star-fishes these organs, instead of being fixed or borne on an immovable support, are placed on the summit of a flexible and muscular, though short, stem; and in this case they probably subserve some additional function besides defence. In the sea-urchins the steps can be followed by which a fixed spine becomes articulated to the shell, and is thus rendered movable. I wish I had space here to give a fuller abstract of Mr. Agassiz's interesting observations on the development of the pedicellariae. All possible gradations, as he adds, may likewise be found between the pedicellariae of the star-fishes and the hooks of the Ophiurians, another group of the Echinodermata; and again between the pedicellariae of sea-urchins and the anchors of the Holothuriae, also belonging to the same great class. Certain compound animals, or zoophytes, as they have been termed, namely the Polyzoa, are provided with curious organs called avicularia. These differ much in structure in the different species. In their most perfect condition they curiously resemble the head and beak of a vulture in miniature, seated on a neck and capable of movement, as is likewise the lower jaw or mandible. In one species observed by me, all the avicularia on the same branch often moved simultaneously backwards and forwards, with the lower jaw widely open, through an angle of about 90 degrees, in the course of five seconds; and their movement caused the whole polyzoary to tremble. When the jaws are touched with a needle they seize it so firmly that the branch can thus be shaken. Mr. Mivart adduces this case, chiefly on account of the supposed difficulty of organs, namely the avicularia of the Polyzoa and the pedicellariae of the Echinodermata, which he considers as "essentially similar," having been developed through natural selection in widely distinct divisions of the animal kingdom. But, as far as structure is concerned, I can see no similarity between tridactyle pedicellariae and avicularia. The latter resembles somewhat more closely the chelae or pincers of Crustaceans; and Mr. Mivart might have adduced with equal appropriateness this resemblance as a special difficulty, or even their resemblance to the head and beak of a bird. The avicularia are believed by Mr. Busk, Dr. Smitt and Dr. Nitsche--naturalists who have carefully studied this group--to be homologous with the zooids and their cells which compose the zoophyte, the movable lip or lid of the cell corresponding with the lower and movable mandible of the avicularium. Mr. Busk, however, does not know of any gradations now existing between a zooid and an avicularium. It is therefore impossible to conjecture by what serviceable gradations the one could have been converted into the other, but it by no means follows from this that such gradations have not existed. As the chelae of Crustaceans resemble in some degree the avicularia of Polyzoa, both serving as pincers, it may be worth while to show that with the former a long series of serviceable gradations still exists. In the first and simplest stage, the terminal segment of a limb shuts down either on the square summit of the broad penultimate segment, or against one whole side, and is thus enabled to catch hold of an object, but the limb still serves as an organ of locomotion. We next find one corner of the broad penultimate segment slightly prominent, sometimes furnished with irregular teeth, and against these the terminal segment shuts down. By an increase in the size of this projection, with its shape, as well as that of the terminal segment, slightly modified and improved, the pincers are rendered more and more perfect, until we have at last an instrument as efficient as the chelae of a lobster. And all these gradations can be actually traced. Besides the avicularia, the polyzoa possess curious organs called vibracula. These generally consist of long bristles, capable of movement and easily excited. In one species examined by me the vibracula were slightly curved and serrated along the outer margin, and all of them on the same polyzoary often moved simultaneously; so that, acting like long oars, they swept a branch rapidly across the object-glass of my microscope. When a branch was placed on its face, the vibracula became entangled, and they made violent efforts to free themselves. They are supposed to serve as a defence, and may be seen, as Mr. Busk remarks, "to sweep slowly and carefully over the surface of the polyzoary, removing what might be noxious to the delicate inhabitants of the cells when their tentacula are protruded." The avicularia, like the vibracula, probably serve for defence, but they also catch and kill small living animals, which, it is believed, are afterwards swept by the currents within reach of the tentacula of the zooids. Some species are provided with avicularia and vibracula, some with avicularia alone and a few with vibracula alone. It is not easy to imagine two objects more widely different in appearance than a bristle or vibraculum, and an avicularium like the head of a bird; yet they are almost certainly homologous and have been developed from the same common source, namely a zooid with its cell. Hence, we can understand how it is that these organs graduate in some cases, as I am informed by Mr. Busk, into each other. Thus, with the avicularia of several species of Lepralia, the movable mandible is so much produced and is so like a bristle that the presence of the upper or fixed beak alone serves to determine its avicularian nature. The vibracula may have been directly developed from the lips of the cells, without having passed through the avicularian stage; but it seems more probable that they have passed through this stage, as during the early stages of the transformation, the other parts of the cell, with the included zooid, could hardly have disappeared at once. In many cases the vibracula have a grooved support at the base, which seems to represent the fixed beak; though this support in some species is quite absent. This view of the development of the vibracula, if trustworthy, is interesting; for supposing that all the species provided with avicularia had become extinct, no one with the most vivid imagination would ever have thought that the vibracula had originally existed as part of an organ, resembling a bird's head, or an irregular box or hood. It is interesting to see two such widely different organs developed from a common origin; and as the movable lip of the cell serves as a protection to the zooid, there is no difficulty in believing that all the gradations, by which the lip became converted first into the lower mandible of an avicularium, and then into an elongated bristle, likewise served as a protection in different ways and under different circumstances. In the vegetable kingdom Mr. Mivart only alludes to two cases, namely the structure of the flowers of orchids, and the movements of climbing plants. With respect to the former, he says: "The explanation of their ORIGIN is deemed thoroughly unsatisfactory--utterly insufficient to explain the incipient, infinitesimal beginnings of structures which are of utility only when they are considerably developed." As I have fully treated this subject in another work, I will here give only a few details on one alone of the most striking peculiarities of the flowers of orchids, namely, their pollinia. A pollinium, when highly developed, consists of a mass of pollen-grains, affixed to an elastic foot-stalk or caudicle, and this to a little mass of extremely viscid matter. The pollinia are by this means transported by insects from one flower to the stigma of another. In some orchids there is no caudicle to the pollen-masses, and the grains are merely tied together by fine threads; but as these are not confined to orchids, they need not here be considered; yet I may mention that at the base of the orchidaceous series, in Cypripedium, we can see how the threads were probably first developed. In other orchids the threads cohere at one end of the pollen-masses; and this forms the first or nascent trace of a caudicle. That this is the origin of the caudicle, even when of considerable length and highly developed, we have good evidence in the aborted pollen-grains which can sometimes be detected embedded within the central and solid parts. With respect to the second chief peculiarity, namely, the little mass of viscid matter attached to the end of the caudicle, a long series of gradations can be specified, each of plain service to the plant. In most flowers belonging to other orders the stigma secretes a little viscid matter. Now, in certain orchids similar viscid matter is secreted, but in much larger quantities by one alone of the three stigmas; and this stigma, perhaps in consequence of the copious secretion, is rendered sterile. When an insect visits a flower of this kind, it rubs off some of the viscid matter, and thus at the same time drags away some of the pollen-grains. From this simple condition, which differs but little from that of a multitude of common flowers, there are endless gradations--to species in which the pollen-mass terminates in a very short, free caudicle--to others in which the caudicle becomes firmly attached to the viscid matter, with the sterile stigma itself much modified. In this latter case we have a pollinium in its most highly developed and perfect condition. He who will carefully examine the flowers of orchids for himself will not deny the existence of the above series of gradations--from a mass of pollen-grains merely tied together by threads, with the stigma differing but little from that of the ordinary flowers, to a highly complex pollinium, admirably adapted for transportal by insects; nor will he deny that all the gradations in the several species are admirably adapted in relation to the general structure of each flower for its fertilisation by different insects. In this, and in almost every other case, the enquiry may be pushed further backwards; and it may be asked how did the stigma of an ordinary flower become viscid, but as we do not know the full history of any one group of beings, it is as useless to ask, as it is hopeless to attempt answering, such questions. We will now turn to climbing plants. These can be arranged in a long series, from those which simply twine round a support, to those which I have called leaf-climbers, and to those provided with tendrils. In these two latter classes the stems have generally, but not always, lost the power of twining, though they retain the power of revolving, which the tendrils likewise possess. The gradations from leaf-climbers to tendril bearers are wonderfully close, and certain plants may be differently placed in either class. But in ascending the series from simple twiners to leaf-climbers, an important quality is added, namely sensitiveness to a touch, by which means the foot-stalks of the leaves or flowers, or these modified and converted into tendrils, are excited to bend round and clasp the touching object. He who will read my memoir on these plants will, I think, admit that all the many gradations in function and structure between simple twiners and tendril-bearers are in each case beneficial in a high degree to the species. For instance, it is clearly a great advantage to a twining plant to become a leaf-climber; and it is probable that every twiner which possessed leaves with long foot-stalks would have been developed into a leaf-climber, if the foot-stalks had possessed in any slight degree the requisite sensitiveness to a touch. As twining is the simplest means of ascending a support, and forms the basis of our series, it may naturally be asked how did plants acquire this power in an incipient degree, afterwards to be improved and increased through natural selection. The power of twining depends, firstly, on the stems while young being extremely flexible (but this is a character common to many plants which are not climbers); and, secondly, on their continually bending to all points of the compass, one after the other in succession, in the same order. By this movement the stems are inclined to all sides, and are made to move round and round. As soon as the lower part of a stem strikes against any object and is stopped, the upper part still goes on bending and revolving, and thus necessarily twines round and up the support. The revolving movement ceases after the early growth of each shoot. As in many widely separated families of plants, single species and single genera possess the power of revolving, and have thus become twiners, they must have independently acquired it, and cannot have inherited it from a common progenitor. Hence, I was led to predict that some slight tendency to a movement of this kind would be found to be far from uncommon with plants which did not climb; and that this had afforded the basis for natural selection to work on and improve. When I made this prediction, I knew of only one imperfect case, namely, of the young flower-peduncles of a Maurandia which revolved slightly and irregularly, like the stems of twining plants, but without making any use of this habit. Soon afterwards Fritz Muller discovered that the young stems of an Alisma and of a Linum--plants which do not climb and are widely separated in the natural system--revolved plainly, though irregularly, and he states that he has reason to suspect that this occurs with some other plants. These slight movements appear to be of no service to the plants in question; anyhow, they are not of the least use in the way of climbing, which is the point that concerns us. Nevertheless we can see that if the stems of these plants had been flexible, and if under the conditions to which they are exposed it had profited them to ascend to a height, then the habit of slightly and irregularly revolving might have been increased and utilised through natural selection, until they had become converted into well-developed twining species. With respect to the sensitiveness of the foot-stalks of the leaves and flowers, and of tendrils, nearly the same remarks are applicable as in the case of the revolving movements of twining plants. As a vast number of species, belonging to widely distinct groups, are endowed with this kind of sensitiveness, it ought to be found in a nascent condition in many plants which have not become climbers. This is the case: I observed that the young flower-peduncles of the above Maurandia curved themselves a little towards the side which was touched. Morren found in several species of Oxalis that the leaves and their foot-stalks moved, especially after exposure to a hot sun, when they were gently and repeatedly touched, or when the plant was shaken. I repeated these observations on some other species of Oxalis with the same result; in some of them the movement was distinct, but was best seen in the young leaves; in others it was extremely slight. It is a more important fact that according to the high authority of Hofmeister, the young shoots and leaves of all plants move after being shaken; and with climbing plants it is, as we know, only during the early stages of growth that the foot-stalks and tendrils are sensitive. It is scarcely possible that the above slight movements, due to a touch or shake, in the young and growing organs of plants, can be of any functional importance to them. But plants possess, in obedience to various stimuli, powers of movement, which are of manifest importance to them; for instance, towards and more rarely from the light--in opposition to, and more rarely in the direction of, the attraction of gravity. When the nerves and muscles of an animal are excited by galvanism or by the absorption of strychnine, the consequent movements may be called an incidental result, for the nerves and muscles have not been rendered specially sensitive to these stimuli. So with plants it appears that, from having the power of movement in obedience to certain stimuli, they are excited in an incidental manner by a touch, or by being shaken. Hence there is no great difficulty in admitting that in the case of leaf-climbers and tendril-bearers, it is this tendency which has been taken advantage of and increased through natural selection. It is, however, probable, from reasons which I have assigned in my memoir, that this will have occurred only with plants which had already acquired the power of revolving, and had thus become twiners. I have already endeavoured to explain how plants became twiners, namely, by the increase of a tendency to slight and irregular revolving movements, which were at first of no use to them; this movement, as well as that due to a touch or shake, being the incidental result of the power of moving, gained for other and beneficial purposes. Whether, during the gradual development of climbing plants, natural selection has been aided by the inherited effects of use, I will not pretend to decide; but we know that certain periodical movements, for instance the so-called sleep of plants, are governed by habit. I have now considered enough, perhaps more than enough, of the cases, selected with care by a skilful naturalist, to prove that natural selection is incompetent to account for the incipient stages of useful structures; and I have shown, as I hope, that there is no great difficulty on this head. A good opportunity has thus been afforded for enlarging a little on gradations of structure, often associated with strange functions--an important subject, which was not treated at sufficient length in the former editions of this work. I will now briefly recapitulate the foregoing cases. With the giraffe, the continued preservation of the individuals of some extinct high-reaching ruminant, which had the longest necks, legs, etc., and could browse a little above the average height, and the continued destruction of those which could not browse so high, would have sufficed for the production of this remarkable quadruped; but the prolonged use of all the parts, together with inheritance, will have aided in an important manner in their co-ordination. With the many insects which imitate various objects, there is no improbability in the belief that an accidental resemblance to some common object was in each case the foundation for the work of natural selection, since perfected through the occasional preservation of slight variations which made the resemblance at all closer; and this will have been carried on as long as the insect continued to vary, and as long as a more and more perfect resemblance led to its escape from sharp-sighted enemies. In certain species of whales there is a tendency to the formation of irregular little points of horn on the palate; and it seems to be quite within the scope of natural selection to preserve all favourable variations, until the points were converted, first into lamellated knobs or teeth, like those on the beak of a goose--then into short lamellae, like those of the domestic ducks--and then into lamellae, as perfect as those of the shoveller-duck--and finally into the gigantic plates of baleen, as in the mouth of the Greenland whale. In the family of the ducks, the lamellae are first used as teeth, then partly as teeth and partly as a sifting apparatus, and at last almost exclusively for this latter purpose. With such structures as the above lamellae of horn or whalebone, habit or use can have done little or nothing, as far as we can judge, towards their development. On the other hand, the transportal of the lower eye of a flat-fish to the upper side of the head, and the formation of a prehensile tail, may be attributed almost wholly to continued use, together with inheritance. With respect to the mammae of the higher animals, the most probable conjecture is that primordially the cutaneous glands over the whole surface of a marsupial sack secreted a nutritious fluid; and that these glands were improved in function through natural selection, and concentrated into a confined area, in which case they would have formed a mamma. There is no more difficulty in understanding how the branched spines of some ancient Echinoderm, which served as a defence, became developed through natural selection into tridactyle pedicellariae, than in understanding the development of the pincers of crustaceans, through slight, serviceable modifications in the ultimate and penultimate segments of a limb, which was at first used solely for locomotion. In the avicularia and vibracula of the Polyzoa we have organs widely different in appearance developed from the same source; and with the vibracula we can understand how the successive gradations might have been of service. With the pollinia of orchids, the threads which originally served to tie together the pollen-grains, can be traced cohering into caudicles; and the steps can likewise be followed by which viscid matter, such as that secreted by the stigmas of ordinary flowers, and still subserving nearly but not quite the same purpose, became attached to the free ends of the caudicles--all these gradations being of manifest benefit to the plants in question. With respect to climbing plants, I need not repeat what has been so lately said. It has often been asked, if natural selection be so potent, why has not this or that structure been gained by certain species, to which it would apparently have been advantageous? But it is unreasonable to expect a precise answer to such questions, considering our ignorance of the past history of each species, and of the conditions which at the present day determine its numbers and range. In most cases only general reasons, but in some few cases special reasons, can be assigned. Thus to adapt a species to new habits of life, many co-ordinated modifications are almost indispensable, and it may often have happened that the requisite parts did not vary in the right manner or to the right degree. Many species must have been prevented from increasing in numbers through destructive agencies, which stood in no relation to certain structures, which we imagine would have been gained through natural selection from appearing to us advantageous to the species. In this case, as the struggle for life did not depend on such structures, they could not have been acquired through natural selection. In many cases complex and long-enduring conditions, often of a peculiar nature, are necessary for the development of a structure; and the requisite conditions may seldom have concurred. The belief that any given structure, which we think, often erroneously, would have been beneficial to a species, would have been gained under all circumstances through natural selection, is opposed to what we can understand of its manner of action. Mr. Mivart does not deny that natural selection has effected something; but he considers it as "demonstrably insufficient" to account for the phenomena which I explain by its agency. His chief arguments have now been considered, and the others will hereafter be considered. They seem to me to partake little of the character of demonstration, and to have little weight in comparison with those in favour of the power of natural selection, aided by the other agencies often specified. I am bound to add, that some of the facts and arguments here used by me, have been advanced for the same purpose in an able article lately published in the "Medico-Chirurgical Review." At the present day almost all naturalists admit evolution under some form. Mr. Mivart believes that species change through "an internal force or tendency," about which it is not pretended that anything is known. That species have a capacity for change will be admitted by all evolutionists; but there is no need, as it seems to me, to invoke any internal force beyond the tendency to ordinary variability, which through the aid of selection, by man has given rise to many well-adapted domestic races, and which, through the aid of natural selection, would equally well give rise by graduated steps to natural races or species. The final result will generally have been, as already explained, an advance, but in some few cases a retrogression, in organisation. Mr. Mivart is further inclined to believe, and some naturalists agree with him, that new species manifest themselves "with suddenness and by modifications appearing at once." For instance, he supposes that the differences between the extinct three-toed Hipparion and the horse arose suddenly. He thinks it difficult to believe that the wing of a bird "was developed in any other way than by a comparatively sudden modification of a marked and important kind;" and apparently he would extend the same view to the wings of bats and pterodactyles. This conclusion, which implies great breaks or discontinuity in the series, appears to me improbable in the highest degree. Everyone who believes in slow and gradual evolution, will of course admit that specific changes may have been as abrupt and as great as any single variation which we meet with under nature, or even under domestication. But as species are more variable when domesticated or cultivated than under their natural conditions, it is not probable that such great and abrupt variations have often occurred under nature, as are known occasionally to arise under domestication. Of these latter variations several may be attributed to reversion; and the characters which thus reappear were, it is probable, in many cases at first gained in a gradual manner. A still greater number must be called monstrosities, such as six-fingered men, porcupine men, Ancon sheep, Niata cattle, etc.; and as they are widely different in character from natural species, they throw very little light on our subject. Excluding such cases of abrupt variations, the few which remain would at best constitute, if found in a state of nature, doubtful species, closely related to their parental types. My reasons for doubting whether natural species have changed as abruptly as have occasionally domestic races, and for entirely disbelieving that they have changed in the wonderful manner indicated by Mr. Mivart, are as follows. According to our experience, abrupt and strongly marked variations occur in our domesticated productions, singly and at rather long intervals of time. If such occurred under nature, they would be liable, as formerly explained, to be lost by accidental causes of destruction and by subsequent intercrossing; and so it is known to be under domestication, unless abrupt variations of this kind are specially preserved and separated by the care of man. Hence, in order that a new species should suddenly appear in the manner supposed by Mr. Mivart, it is almost necessary to believe, in opposition to all analogy, that several wonderfully changed individuals appeared simultaneously within the same district. This difficulty, as in the case of unconscious selection by man, is avoided on the theory of gradual evolution, through the preservation of a large number of individuals, which varied more or less in any favourable direction, and of the destruction of a large number which varied in an opposite manner. That many species have been evolved in an extremely gradual manner, there can hardly be a doubt. The species and even the genera of many large natural families are so closely allied together that it is difficult to distinguish not a few of them. On every continent, in proceeding from north to south, from lowland to upland, etc., we meet with a host of closely related or representative species; as we likewise do on certain distinct continents, which we have reason to believe were formerly connected. But in making these and the following remarks, I am compelled to allude to subjects hereafter to be discussed. Look at the many outlying islands round a continent, and see how many of their inhabitants can be raised only to the rank of doubtful species. So it is if we look to past times, and compare the species which have just passed away with those still living within the same areas; or if we compare the fossil species embedded in the sub-stages of the same geological formation. It is indeed manifest that multitudes of species are related in the closest manner to other species that still exist, or have lately existed; and it will hardly be maintained that such species have been developed in an abrupt or sudden manner. Nor should it be forgotten, when we look to the special parts of allied species, instead of to distinct species, that numerous and wonderfully fine gradations can be traced, connecting together widely different structures. Many large groups of facts are intelligible only on the principle that species have been evolved by very small steps. For instance, the fact that the species included in the larger genera are more closely related to each other, and present a greater number of varieties than do the species in the smaller genera. The former are also grouped in little clusters, like varieties round species; and they present other analogies with varieties, as was shown in our second chapter. On this same principle we can understand how it is that specific characters are more variable than generic characters; and how the parts which are developed in an extraordinary degree or manner are more variable than other parts of the same species. Many analogous facts, all pointing in the same direction, could be added. Although very many species have almost certainly been produced by steps not greater than those separating fine varieties; yet it may be maintained that some have been developed in a different and abrupt manner. Such an admission, however, ought not to be made without strong evidence being assigned. The vague and in some respects false analogies, as they have been shown to be by Mr. Chauncey Wright, which have been advanced in favour of this view, such as the sudden crystallisation of inorganic substances, or the falling of a facetted spheroid from one facet to another, hardly deserve consideration. One class of facts, however, namely, the sudden appearance of new and distinct forms of life in our geological formations supports at first sight the belief in abrupt development. But the value of this evidence depends entirely on the perfection of the geological record, in relation to periods remote in the history of the world. If the record is as fragmentary as many geologists strenuously assert, there is nothing strange in new forms appearing as if suddenly developed. Unless we admit transformations as prodigious as those advocated by Mr. Mivart, such as the sudden development of the wings of birds or bats, or the sudden conversion of a Hipparion into a horse, hardly any light is thrown by the belief in abrupt modifications on the deficiency of connecting links in our geological formations. But against the belief in such abrupt changes, embryology enters a strong protest. It is notorious that the wings of birds and bats, and the legs of horses or other quadrupeds, are undistinguishable at an early embryonic period, and that they become differentiated by insensibly fine steps. Embryological resemblances of all kinds can be accounted for, as we shall hereafter see, by the progenitors of our existing species having varied after early youth, and having transmitted their newly-acquired characters to their offspring, at a corresponding age. The embryo is thus left almost unaffected, and serves as a record of the past condition of the species. Hence it is that existing species during the early stages of their development so often resemble ancient and extinct forms belonging to the same class. On this view of the meaning of embryological resemblances, and indeed on any view, it is incredible that an animal should have undergone such momentous and abrupt transformations as those above indicated, and yet should not bear even a trace in its embryonic condition of any sudden modification, every detail in its structure being developed by insensibly fine steps. He who believes that some ancient form was transformed suddenly through an internal force or tendency into, for instance, one furnished with wings, will be almost compelled to assume, in opposition to all analogy, that many individuals varied simultaneously. It cannot be denied that such abrupt and great changes of structure are widely different from those which most species apparently have undergone. He will further be compelled to believe that many structures beautifully adapted to all the other parts of the same creature and to the surrounding conditions, have been suddenly produced; and of such complex and wonderful co-adaptations, he will not be able to assign a shadow of an explanation. He will be forced to admit that these great and sudden transformations have left no trace of their action on the embryo. To admit all this is, as it seems to me, to enter into the realms of miracle, and to leave those of science. CHAPTER VIII. INSTINCT. Instincts comparable with habits, but different in their origin--Instincts graduated--Aphides and ants--Instincts variable--Domestic instincts, their origin--Natural instincts of the cuckoo, molothrus, ostrich, and parasitic bees--Slave-making ants--Hive-bee, its cell-making instinct--Changes of instinct and structure not necessarily simultaneous--Difficulties of the theory of the Natural Selection of instincts--Neuter or sterile insects--Summary. Many instincts are so wonderful that their development will probably appear to the reader a difficulty sufficient to overthrow my whole theory. I may here premise, that I have nothing to do with the origin of the mental powers, any more than I have with that of life itself. We are concerned only with the diversities of instinct and of the other mental faculties in animals of the same class. I will not attempt any definition of instinct. It would be easy to show that several distinct mental actions are commonly embraced by this term; but every one understands what is meant, when it is said that instinct impels the cuckoo to migrate and to lay her eggs in other birds' nests. An action, which we ourselves require experience to enable us to perform, when performed by an animal, more especially by a very young one, without experience, and when performed by many individuals in the same way, without their knowing for what purpose it is performed, is usually said to be instinctive. But I could show that none of these characters are universal. A little dose of judgment or reason, as Pierre Huber expresses it, often comes into play, even with animals low in the scale of nature. Frederick Cuvier and several of the older metaphysicians have compared instinct with habit. This comparison gives, I think, an accurate notion of the frame of mind under which an instinctive action is performed, but not necessarily of its origin. How unconsciously many habitual actions are performed, indeed not rarely in direct opposition to our conscious will! yet they may be modified by the will or reason. Habits easily become associated with other habits, with certain periods of time and states of the body. When once acquired, they often remain constant throughout life. Several other points of resemblance between instincts and habits could be pointed out. As in repeating a well-known song, so in instincts, one action follows another by a sort of rhythm; if a person be interrupted in a song, or in repeating anything by rote, he is generally forced to go back to recover the habitual train of thought: so P. Huber found it was with a caterpillar, which makes a very complicated hammock; for if he took a caterpillar which had completed its hammock up to, say, the sixth stage of construction, and put it into a hammock completed up only to the third stage, the caterpillar simply re-performed the fourth, fifth, and sixth stages of construction. If, however, a caterpillar were taken out of a hammock made up, for instance, to the third stage, and were put into one finished up to the sixth stage, so that much of its work was already done for it, far from deriving any benefit from this, it was much embarrassed, and, in order to complete its hammock, seemed forced to start from the third stage, where it had left off, and thus tried to complete the already finished work. If we suppose any habitual action to become inherited--and it can be shown that this does sometimes happen--then the resemblance between what originally was a habit and an instinct becomes so close as not to be distinguished. If Mozart, instead of playing the pianoforte at three years old with wonderfully little practice, had played a tune with no practice at all, be might truly be said to have done so instinctively. But it would be a serious error to suppose that the greater number of instincts have been acquired by habit in one generation, and then transmitted by inheritance to succeeding generations. It can be clearly shown that the most wonderful instincts with which we are acquainted, namely, those of the hive-bee and of many ants, could not possibly have been acquired by habit. It will be universally admitted that instincts are as important as corporeal structures for the welfare of each species, under its present conditions of life. Under changed conditions of life, it is at least possible that slight modifications of instinct might be profitable to a species; and if it can be shown that instincts do vary ever so little, then I can see no difficulty in natural selection preserving and continually accumulating variations of instinct to any extent that was profitable. It is thus, as I believe, that all the most complex and wonderful instincts have originated. As modifications of corporeal structure arise from, and are increased by, use or habit, and are diminished or lost by disuse, so I do not doubt it has been with instincts. But I believe that the effects of habit are in many cases of subordinate importance to the effects of the natural selection of what may be called spontaneous variations of instincts;--that is of variations produced by the same unknown causes which produce slight deviations of bodily structure. No complex instinct can possibly be produced through natural selection, except by the slow and gradual accumulation of numerous, slight, yet profitable, variations. Hence, as in the case of corporeal structures, we ought to find in nature, not the actual transitional gradations by which each complex instinct has been acquired--for these could be found only in the lineal ancestors of each species--but we ought to find in the collateral lines of descent some evidence of such gradations; or we ought at least to be able to show that gradations of some kind are possible; and this we certainly can do. I have been surprised to find, making allowance for the instincts of animals having been but little observed, except in Europe and North America, and for no instinct being known among extinct species, how very generally gradations, leading to the most complex instincts, can be discovered. Changes of instinct may sometimes be facilitated by the same species having different instincts at different periods of life, or at different seasons of the year, or when placed under different circumstances, etc.; in which case either the one or the other instinct might be preserved by natural selection. And such instances of diversity of instinct in the same species can be shown to occur in nature. Again, as in the case of corporeal structure, and conformably to my theory, the instinct of each species is good for itself, but has never, as far as we can judge, been produced for the exclusive good of others. One of the strongest instances of an animal apparently performing an action for the sole good of another, with which I am acquainted, is that of aphides voluntarily yielding, as was first observed by Huber, their sweet excretion to ants: that they do so voluntarily, the following facts show. I removed all the ants from a group of about a dozen aphides on a dock-plant, and prevented their attendance during several hours. After this interval, I felt sure that the aphides would want to excrete. I watched them for some time through a lens, but not one excreted; I then tickled and stroked them with a hair in the same manner, as well as I could, as the ants do with their antennae; but not one excreted. Afterwards, I allowed an ant to visit them, and it immediately seemed, by its eager way of running about to be well aware what a rich flock it had discovered; it then began to play with its antennae on the abdomen first of one aphis and then of another; and each, as soon as it felt the antennae, immediately lifted up its abdomen and excreted a limpid drop of sweet juice, which was eagerly devoured by the ant. Even the quite young aphides behaved in this manner, showing that the action was instinctive, and not the result of experience. It is certain, from the observations of Huber, that the aphides show no dislike to the ants: if the latter be not present they are at last compelled to eject their excretion. But as the excretion is extremely viscid, it is no doubt a convenience to the aphides to have it removed; therefore probably they do not excrete solely for the good of the ants. Although there is no evidence that any animal performs an action for the exclusive good of another species, yet each tries to take advantage of the instincts of others, as each takes advantage of the weaker bodily structure of other species. So again certain instincts cannot be considered as absolutely perfect; but as details on this and other such points are not indispensable, they may be here passed over. As some degree of variation in instincts under a state of nature, and the inheritance of such variations, are indispensable for the action of natural selection, as many instances as possible ought to be given; but want of space prevents me. I can only assert that instincts certainly do vary--for instance, the migratory instinct, both in extent and direction, and in its total loss. So it is with the nests of birds, which vary partly in dependence on the situations chosen, and on the nature and temperature of the country inhabited, but often from causes wholly unknown to us. Audubon has given several remarkable cases of differences in the nests of the same species in the northern and southern United States. Why, it has been asked, if instinct be variable, has it not granted to the bee "the ability to use some other material when wax was deficient?" But what other natural material could bees use? They will work, as I have seen, with wax hardened with vermilion or softened with lard. Andrew Knight observed that his bees, instead of laboriously collecting propolis, used a cement of wax and turpentine, with which he had covered decorticated trees. It has lately been shown that bees, instead of searching for pollen, will gladly use a very different substance, namely, oatmeal. Fear of any particular enemy is certainly an instinctive quality, as may be seen in nestling birds, though it is strengthened by experience, and by the sight of fear of the same enemy in other animals. The fear of man is slowly acquired, as I have elsewhere shown, by the various animals which inhabit desert islands; and we see an instance of this, even in England, in the greater wildness of all our large birds in comparison with our small birds; for the large birds have been most persecuted by man. We may safely attribute the greater wildness of our large birds to this cause; for in uninhabited islands large birds are not more fearful than small; and the magpie, so wary in England, is tame in Norway, as is the hooded crow in Egypt. That the mental qualities of animals of the same kind, born in a state of nature, vary much, could be shown by many facts. Several cases could also be adduced of occasional and strange habits in wild animals, which, if advantageous to the species, might have given rise, through natural selection, to new instincts. But I am well aware that these general statements, without the facts in detail, can produce but a feeble effect on the reader's mind. I can only repeat my assurance, that I do not speak without good evidence. INHERITED CHANGES OF HABIT OR INSTINCT IN DOMESTICATED ANIMALS. The possibility, or even probability, of inherited variations of instinct in a state of nature will be strengthened by briefly considering a few cases under domestication. We shall thus be enabled to see the part which habit and the selection of so-called spontaneous variations have played in modifying the mental qualities of our domestic animals. It is notorious how much domestic animals vary in their mental qualities. With cats, for instance, one naturally takes to catching rats, and another mice, and these tendencies are known to be inherited. One cat, according to Mr. St. John, always brought home game birds, another hares or rabbits, and another hunted on marshy ground and almost nightly caught woodcocks or snipes. A number of curious and authentic instances could be given of various shades of disposition and taste, and likewise of the oddest tricks, associated with certain frames of mind or periods of time. But let us look to the familiar case of the breeds of dogs: it cannot be doubted that young pointers (I have myself seen striking instances) will sometimes point and even back other dogs the very first time that they are taken out; retrieving is certainly in some degree inherited by retrievers; and a tendency to run round, instead of at, a flock of sheep, by shepherd-dogs. I cannot see that these actions, performed without experience by the young, and in nearly the same manner by each individual, performed with eager delight by each breed, and without the end being known--for the young pointer can no more know that he points to aid his master, than the white butterfly knows why she lays her eggs on the leaf of the cabbage--I cannot see that these actions differ essentially from true instincts. If we were to behold one kind of wolf, when young and without any training, as soon as it scented its prey, stand motionless like a statue, and then slowly crawl forward with a peculiar gait; and another kind of wolf rushing round, instead of at, a herd of deer, and driving them to a distant point, we should assuredly call these actions instinctive. Domestic instincts, as they may be called, are certainly far less fixed than natural instincts; but they have been acted on by far less rigorous selection, and have been transmitted for an incomparably shorter period, under less fixed conditions of life. How strongly these domestic instincts, habits, and dispositions are inherited, and how curiously they become mingled, is well shown when different breeds of dogs are crossed. Thus it is known that a cross with a bull-dog has affected for many generations the courage and obstinacy of greyhounds; and a cross with a greyhound has given to a whole family of shepherd-dogs a tendency to hunt hares. These domestic instincts, when thus tested by crossing, resemble natural instincts, which in a like manner become curiously blended together, and for a long period exhibit traces of the instincts of either parent: for example, Le Roy describes a dog, whose great-grandfather was a wolf, and this dog showed a trace of its wild parentage only in one way, by not coming in a straight line to his master, when called. Domestic instincts are sometimes spoken of as actions which have become inherited solely from long-continued and compulsory habit, but this is not true. No one would ever have thought of teaching, or probably could have taught, the tumbler-pigeon to tumble--an action which, as I have witnessed, is performed by young birds, that have never seen a pigeon tumble. We may believe that some one pigeon showed a slight tendency to this strange habit, and that the long-continued selection of the best individuals in successive generations made tumblers what they now are; and near Glasgow there are house-tumblers, as I hear from Mr. Brent, which cannot fly eighteen inches high without going head over heels. It may be doubted whether any one would have thought of training a dog to point, had not some one dog naturally shown a tendency in this line; and this is known occasionally to happen, as I once saw, in a pure terrier: the act of pointing is probably, as many have thought, only the exaggerated pause of an animal preparing to spring on its prey. When the first tendency to point was once displayed, methodical selection and the inherited effects of compulsory training in each successive generation would soon complete the work; and unconscious selection is still in progress, as each man tries to procure, without intending to improve the breed, dogs which stand and hunt best. On the other hand, habit alone in some cases has sufficed; hardly any animal is more difficult to tame than the young of the wild rabbit; scarcely any animal is tamer than the young of the tame rabbit; but I can hardly suppose that domestic rabbits have often been selected for tameness alone; so that we must attribute at least the greater part of the inherited change from extreme wildness to extreme tameness, to habit and long-continued close confinement. Natural instincts are lost under domestication: a remarkable instance of this is seen in those breeds of fowls which very rarely or never become "broody," that is, never wish to sit on their eggs. Familiarity alone prevents our seeing how largely and how permanently the minds of our domestic animals have been modified. It is scarcely possible to doubt that the love of man has become instinctive in the dog. All wolves, foxes, jackals and species of the cat genus, when kept tame, are most eager to attack poultry, sheep and pigs; and this tendency has been found incurable in dogs which have been brought home as puppies from countries such as Tierra del Fuego and Australia, where the savages do not keep these domestic animals. How rarely, on the other hand, do our civilised dogs, even when quite young, require to be taught not to attack poultry, sheep, and pigs! No doubt they occasionally do make an attack, and are then beaten; and if not cured, they are destroyed; so that habit and some degree of selection have probably concurred in civilising by inheritance our dogs. On the other hand, young chickens have lost wholly by habit, that fear of the dog and cat which no doubt was originally instinctive in them, for I am informed by Captain Hutton that the young chickens of the parent stock, the Gallus bankiva, when reared in India under a hen, are at first excessively wild. So it is with young pheasants reared in England under a hen. It is not that chickens have lost all fear, but fear only of dogs and cats, for if the hen gives the danger chuckle they will run (more especially young turkeys) from under her and conceal themselves in the surrounding grass or thickets; and this is evidently done for the instinctive purpose of allowing, as we see in wild ground-birds, their mother to fly away. But this instinct retained by our chickens has become useless under domestication, for the mother-hen has almost lost by disuse the power of flight. Hence, we may conclude that under domestication instincts have been acquired and natural instincts have been lost, partly by habit and partly by man selecting and accumulating, during successive generations, peculiar mental habits and actions, which at first appeared from what we must in our ignorance call an accident. In some cases compulsory habit alone has sufficed to produce inherited mental changes; in other cases compulsory habit has done nothing, and all has been the result of selection, pursued both methodically and unconsciously; but in most cases habit and selection have probably concurred. SPECIAL INSTINCTS. We shall, perhaps, best understand how instincts in a state of nature have become modified by selection by considering a few cases. I will select only three, namely, the instinct which leads the cuckoo to lay her eggs in other birds' nests; the slave-making instinct of certain ants; and the cell-making power of the hive-bee: these two latter instincts have generally and justly been ranked by naturalists as the most wonderful of all known instincts. INSTINCTS OF THE CUCKOO. It is supposed by some naturalists that the more immediate cause of the instinct of the cuckoo is that she lays her eggs, not daily, but at intervals of two or three days; so that, if she were to make her own nest and sit on her own eggs, those first laid would have to be left for some time unincubated or there would be eggs and young birds of different ages in the same nest. If this were the case the process of laying and hatching might be inconveniently long, more especially as she migrates at a very early period; and the first hatched young would probably have to be fed by the male alone. But the American cuckoo is in this predicament, for she makes her own nest and has eggs and young successively hatched, all at the same time. It has been both asserted and denied that the American cuckoo occasionally lays her eggs in other birds' nests; but I have lately heard from Dr. Merrill, of Iowa, that he once found in Illinois a young cuckoo, together with a young jay in the nest of a blue jay (Garrulus cristatus); and as both were nearly full feathered, there could be no mistake in their identification. I could also give several instances of various birds which have been known occasionally to lay their eggs in other birds' nests. Now let us suppose that the ancient progenitor of our European cuckoo had the habits of the American cuckoo, and that she occasionally laid an egg in another bird's nest. If the old bird profited by this occasional habit through being enabled to emigrate earlier or through any other cause; or if the young were made more vigorous by advantage being taken of the mistaken instinct of another species than when reared by their own mother, encumbered as she could hardly fail to be by having eggs and young of different ages at the same time, then the old birds or the fostered young would gain an advantage. And analogy would lead us to believe that the young thus reared would be apt to follow by inheritance the occasional and aberrant habit of their mother, and in their turn would be apt to lay their eggs in other birds' nests, and thus be more successful in rearing their young. By a continued process of this nature, I believe that the strange instinct of our cuckoo has been generated. It has, also recently been ascertained on sufficient evidence, by Adolf Muller, that the cuckoo occasionally lays her eggs on the bare ground, sits on them and feeds her young. This rare event is probably a case of reversion to the long-lost, aboriginal instinct of nidification. It has been objected that I have not noticed other related instincts and adaptations of structure in the cuckoo, which are spoken of as necessarily co-ordinated. But in all cases, speculation on an instinct known to us only in a single species, is useless, for we have hitherto had no facts to guide us. Until recently the instincts of the European and of the non-parasitic American cuckoo alone were known; now, owing to Mr. Ramsay's observations, we have learned something about three Australian species, which lay their eggs in other birds' nests. The chief points to be referred to are three: first, that the common cuckoo, with rare exceptions, lays only one egg in a nest, so that the large and voracious young bird receives ample food. Secondly, that the eggs are remarkably small, not exceeding those of the skylark--a bird about one-fourth as large as the cuckoo. That the small size of the egg is a real case of adaptation we may infer from the fact of the mon-parasitic American cuckoo laying full-sized eggs. Thirdly, that the young cuckoo, soon after birth, has the instinct, the strength and a properly shaped back for ejecting its foster-brothers, which then perish from cold and hunger. This has been boldly called a beneficent arrangement, in order that the young cuckoo may get sufficient food, and that its foster-brothers may perish before they had acquired much feeling! Turning now to the Australian species: though these birds generally lay only one egg in a nest, it is not rare to find two and even three eggs in the same nest. In the bronze cuckoo the eggs vary greatly in size, from eight to ten lines in length. Now, if it had been of an advantage to this species to have laid eggs even smaller than those now laid, so as to have deceived certain foster-parents, or, as is more probable, to have been hatched within a shorter period (for it is asserted that there is a relation between the size of eggs and the period of their incubation), then there is no difficulty in believing that a race or species might have been formed which would have laid smaller and smaller eggs; for these would have been more safely hatched and reared. Mr. Ramsay remarks that two of the Australian cuckoos, when they lay their eggs in an open nest, manifest a decided preference for nests containing eggs similar in colour to their own. The European species apparently manifests some tendency towards a similar instinct, but not rarely departs from it, as is shown by her laying her dull and pale-coloured eggs in the nest of the hedge-warbler with bright greenish-blue eggs. Had our cuckoo invariably displayed the above instinct, it would assuredly have been added to those which it is assumed must all have been acquired together. The eggs of the Australian bronze cuckoo vary, according to Mr. Ramsay, to an extraordinary degree in colour; so that in this respect, as well as in size, natural selection might have secured and fixed any advantageous variation. In the case of the European cuckoo, the offspring of the foster-parents are commonly ejected from the nest within three days after the cuckoo is hatched; and as the latter at this age is in a most helpless condition, Mr. Gould was formerly inclined to believe that the act of ejection was performed by the foster-parents themselves. But he has now received a trustworthy account of a young cuckoo which was actually seen, while still blind and not able even to hold up its own head, in the act of ejecting its foster-brothers. One of these was replaced in the nest by the observer, and was again thrown out. With respect to the means by which this strange and odious instinct was acquired, if it were of great importance for the young cuckoo, as is probably the case, to receive as much food as possible soon after birth, I can see no special difficulty in its having gradually acquired, during successive generations, the blind desire, the strength, and structure necessary for the work of ejection; for those cuckoos which had such habits and structure best developed would be the most securely reared. The first step towards the acquisition of the proper instinct might have been mere unintentional restlessness on the part of the young bird, when somewhat advanced in age and strength; the habit having been afterwards improved, and transmitted to an earlier age. I can see no more difficulty in this than in the unhatched young of other birds acquiring the instinct to break through their own shells; or than in young snakes acquiring in their upper jaws, as Owen has remarked, a transitory sharp tooth for cutting through the tough egg-shell. For if each part is liable to individual variations at all ages, and the variations tend to be inherited at a corresponding or earlier age--propositions which cannot be disputed--then the instincts and structure of the young could be slowly modified as surely as those of the adult; and both cases must stand or fall together with the whole theory of natural selection. Some species of Molothrus, a widely distinct genus of American birds, allied to our starlings, have parasitic habits like those of the cuckoo; and the species present an interesting gradation in the perfection of their instincts. The sexes of Molothrus badius are stated by an excellent observer, Mr. Hudson, sometimes to live promiscuously together in flocks, and sometimes to pair. They either build a nest of their own or seize on one belonging to some other bird, occasionally throwing out the nestlings of the stranger. They either lay their eggs in the nest thus appropriated, or oddly enough build one for themselves on the top of it. They usually sit on their own eggs and rear their own young; but Mr. Hudson says it is probable that they are occasionally parasitic, for he has seen the young of this species following old birds of a distinct kind and clamouring to be fed by them. The parasitic habits of another species of Molothrus, the M. bonariensis, are much more highly developed than those of the last, but are still far from perfect. This bird, as far as it is known, invariably lays its eggs in the nests of strangers; but it is remarkable that several together sometimes commence to build an irregular untidy nest of their own, placed in singular ill-adapted situations, as on the leaves of a large thistle. They never, however, as far as Mr. Hudson has ascertained, complete a nest for themselves. They often lay so many eggs--from fifteen to twenty--in the same foster-nest, that few or none can possibly be hatched. They have, moreover, the extraordinary habit of pecking holes in the eggs, whether of their own species or of their foster parents, which they find in the appropriated nests. They drop also many eggs on the bare ground, which are thus wasted. A third species, the M. pecoris of North America, has acquired instincts as perfect as those of the cuckoo, for it never lays more than one egg in a foster-nest, so that the young bird is securely reared. Mr. Hudson is a strong disbeliever in evolution, but he appears to have been so much struck by the imperfect instincts of the Molothrus bonariensis that he quotes my words, and asks, "Must we consider these habits, not as especially endowed or created instincts, but as small consequences of one general law, namely, transition?" Various birds, as has already been remarked, occasionally lay their eggs in the nests of other birds. This habit is not very uncommon with the Gallinaceae, and throws some light on the singular instinct of the ostrich. In this family several hen birds unite and lay first a few eggs in one nest and then in another; and these are hatched by the males. This instinct may probably be accounted for by the fact of the hens laying a large number of eggs, but, as with the cuckoo, at intervals of two or three days. The instinct, however, of the American ostrich, as in the case of the Molothrus bonariensis, has not as yet been perfected; for a surprising number of eggs lie strewed over the plains, so that in one day's hunting I picked up no less than twenty lost and wasted eggs. Many bees are parasitic, and regularly lay their eggs in the nests of other kinds of bees. This case is more remarkable than that of the cuckoo; for these bees have not only had their instincts but their structure modified in accordance with their parasitic habits; for they do not possess the pollen-collecting apparatus which would have been indispensable if they had stored up food for their own young. Some species of Sphegidae (wasp-like insects) are likewise parasitic; and M. Fabre has lately shown good reason for believing that, although the Tachytes nigra generally makes its own burrow and stores it with paralysed prey for its own larvae, yet that, when this insect finds a burrow already made and stored by another sphex, it takes advantage of the prize, and becomes for the occasion parasitic. In this case, as with that of the Molothrus or cuckoo, I can see no difficulty in natural selection making an occasional habit permanent, if of advantage to the species, and if the insect whose nest and stored food are feloniously appropriated, be not thus exterminated. SLAVE-MAKING INSTINCT. This remarkable instinct was first discovered in the Formica (Polyerges) rufescens by Pierre Huber, a better observer even than his celebrated father. This ant is absolutely dependent on its slaves; without their aid, the species would certainly become extinct in a single year. The males and fertile females do no work of any kind, and the workers or sterile females, though most energetic and courageous in capturing slaves, do no other work. They are incapable of making their own nests, or of feeding their own larvae. When the old nest is found inconvenient, and they have to migrate, it is the slaves which determine the migration, and actually carry their masters in their jaws. So utterly helpless are the masters, that when Huber shut up thirty of them without a slave, but with plenty of the food which they like best, and with their larvae and pupae to stimulate them to work, they did nothing; they could not even feed themselves, and many perished of hunger. Huber then introduced a single slave (F. fusca), and she instantly set to work, fed and saved the survivors; made some cells and tended the larvae, and put all to rights. What can be more extraordinary than these well-ascertained facts? If we had not known of any other slave-making ant, it would have been hopeless to speculate how so wonderful an instinct could have been perfected. Another species, Formica sanguinea, was likewise first discovered by P. Huber to be a slave-making ant. This species is found in the southern parts of England, and its habits have been attended to by Mr. F. Smith, of the British Museum, to whom I am much indebted for information on this and other subjects. Although fully trusting to the statements of Huber and Mr. Smith, I tried to approach the subject in a sceptical frame of mind, as any one may well be excused for doubting the existence of so extraordinary an instinct as that of making slaves. Hence, I will give the observations which I made in some little detail. I opened fourteen nests of F. sanguinea, and found a few slaves in all. Males and fertile females of the slave-species (F. fusca) are found only in their own proper communities, and have never been observed in the nests of F. sanguinea. The slaves are black and not above half the size of their red masters, so that the contrast in their appearance is great. When the nest is slightly disturbed, the slaves occasionally come out, and like their masters are much agitated and defend the nest: when the nest is much disturbed, and the larvae and pupae are exposed, the slaves work energetically together with their masters in carrying them away to a place of safety. Hence, it is clear that the slaves feel quite at home. During the months of June and July, on three successive years, I watched for many hours several nests in Surrey and Sussex, and never saw a slave either leave or enter a nest. As, during these months, the slaves are very few in number, I thought that they might behave differently when more numerous; but Mr. Smith informs me that he has watched the nests at various hours during May, June and August, both in Surrey and Hampshire, and has never seen the slaves, though present in large numbers in August, either leave or enter the nest. Hence, he considers them as strictly household slaves. The masters, on the other hand, may be constantly seen bringing in materials for the nest, and food of all kinds. During the year 1860, however, in the month of July, I came across a community with an unusually large stock of slaves, and I observed a few slaves mingled with their masters leaving the nest, and marching along the same road to a tall Scotch-fir tree, twenty-five yards distant, which they ascended together, probably in search of aphides or cocci. According to Huber, who had ample opportunities for observation, the slaves in Switzerland habitually work with their masters in making the nest, and they alone open and close the doors in the morning and evening; and, as Huber expressly states, their principal office is to search for aphides. This difference in the usual habits of the masters and slaves in the two countries, probably depends merely on the slaves being captured in greater numbers in Switzerland than in England. One day I fortunately witnessed a migration of F. sanguinea from one nest to another, and it was a most interesting spectacle to behold the masters carefully carrying their slaves in their jaws instead of being carried by them, as in the case of F. rufescens. Another day my attention was struck by about a score of the slave-makers haunting the same spot, and evidently not in search of food; they approached and were vigorously repulsed by an independent community of the slave species (F. fusca); sometimes as many as three of these ants clinging to the legs of the slave-making F. sanguinea. The latter ruthlessly killed their small opponents and carried their dead bodies as food to their nest, twenty-nine yards distant; but they were prevented from getting any pupae to rear as slaves. I then dug up a small parcel of the pupae of F. fusca from another nest, and put them down on a bare spot near the place of combat; they were eagerly seized and carried off by the tyrants, who perhaps fancied that, after all, they had been victorious in their late combat. At the same time I laid on the same place a small parcel of the pupae of another species, F. flava, with a few of these little yellow ants still clinging to the fragments of their nest. This species is sometimes, though rarely, made into slaves, as has been described by Mr. Smith. Although so small a species, it is very courageous, and I have seen it ferociously attack other ants. In one instance I found to my surprise an independent community of F. flava under a stone beneath a nest of the slave-making F. sanguinea; and when I had accidentally disturbed both nests, the little ants attacked their big neighbours with surprising courage. Now I was curious to ascertain whether F. sanguinea could distinguish the pupae of F. fusca, which they habitually make into slaves, from those of the little and furious F. flava, which they rarely capture, and it was evident that they did at once distinguish them; for we have seen that they eagerly and instantly seized the pupae of F. fusca, whereas they were much terrified when they came across the pupae, or even the earth from the nest, of F. flava, and quickly ran away; but in about a quarter of an hour, shortly after all the little yellow ants had crawled away, they took heart and carried off the pupae. One evening I visited another community of F. sanguinea, and found a number of these ants returning home and entering their nests, carrying the dead bodies of F. fusca (showing that it was not a migration) and numerous pupae. I traced a long file of ants burdened with booty, for about forty yards back, to a very thick clump of heath, whence I saw the last individual of F. sanguinea emerge, carrying a pupa; but I was not able to find the desolated nest in the thick heath. The nest, however, must have been close at hand, for two or three individuals of F. fusca were rushing about in the greatest agitation, and one was perched motionless with its own pupa in its mouth on the top of a spray of heath, an image of despair over its ravaged home. Such are the facts, though they did not need confirmation by me, in regard to the wonderful instinct of making slaves. Let it be observed what a contrast the instinctive habits of F. sanguinea present with those of the continental F. rufescens. The latter does not build its own nest, does not determine its own migrations, does not collect food for itself or its young, and cannot even feed itself: it is absolutely dependent on its numerous slaves. Formica sanguinea, on the other hand, possesses much fewer slaves, and in the early part of the summer extremely few. The masters determine when and where a new nest shall be formed, and when they migrate, the masters carry the slaves. Both in Switzerland and England the slaves seem to have the exclusive care of the larvae, and the masters alone go on slave-making expeditions. In Switzerland the slaves and masters work together, making and bringing materials for the nest: both, but chiefly the slaves, tend and milk as it may be called, their aphides; and thus both collect food for the community. In England the masters alone usually leave the nest to collect building materials and food for themselves, their slaves and larvae. So that the masters in this country receive much less service from their slaves than they do in Switzerland. By what steps the instinct of F. sanguinea originated I will not pretend to conjecture. But as ants which are not slave-makers, will, as I have seen, carry off pupae of other species, if scattered near their nests, it is possible that such pupae originally stored as food might become developed; and the foreign ants thus unintentionally reared would then follow their proper instincts, and do what work they could. If their presence proved useful to the species which had seized them--if it were more advantageous to this species, to capture workers than to procreate them--the habit of collecting pupae, originally for food, might by natural selection be strengthened and rendered permanent for the very different purpose of raising slaves. When the instinct was once acquired, if carried out to a much less extent even than in our British F. sanguinea, which, as we have seen, is less aided by its slaves than the same species in Switzerland, natural selection might increase and modify the instinct--always supposing each modification to be of use to the species--until an ant was formed as abjectly dependent on its slaves as is the Formica rufescens. CELL-MAKING INSTINCT OF THE HIVE-BEE. I will not here enter on minute details on this subject, but will merely give an outline of the conclusions at which I have arrived. He must be a dull man who can examine the exquisite structure of a comb, so beautifully adapted to its end, without enthusiastic admiration. We hear from mathematicians that bees have practically solved a recondite problem, and have made their cells of the proper shape to hold the greatest possible amount of honey, with the least possible consumption of precious wax in their construction. It has been remarked that a skilful workman, with fitting tools and measures, would find it very difficult to make cells of wax of the true form, though this is effected by a crowd of bees working in a dark hive. Granting whatever instincts you please, it seems at first quite inconceivable how they can make all the necessary angles and planes, or even perceive when they are correctly made. But the difficulty is not nearly so great as at first appears: all this beautiful work can be shown, I think, to follow from a few simple instincts. I was led to investigate this subject by Mr. Waterhouse, who has shown that the form of the cell stands in close relation to the presence of adjoining cells; and the following view may, perhaps, be considered only as a modification of his theory. Let us look to the great principle of gradation, and see whether Nature does not reveal to us her method of work. At one end of a short series we have humble-bees, which use their old cocoons to hold honey, sometimes adding to them short tubes of wax, and likewise making separate and very irregular rounded cells of wax. At the other end of the series we have the cells of the hive-bee, placed in a double layer: each cell, as is well known, is an hexagonal prism, with the basal edges of its six sides bevelled so as to join an inverted pyramid, of three rhombs. These rhombs have certain angles, and the three which form the pyramidal base of a single cell on one side of the comb, enter into the composition of the bases of three adjoining cells on the opposite side. In the series between the extreme perfection of the cells of the hive-bee and the simplicity of those of the humble-bee, we have the cells of the Mexican Melipona domestica, carefully described and figured by Pierre Huber. The Melipona itself is intermediate in structure between the hive and humble bee, but more nearly related to the latter: it forms a nearly regular waxen comb of cylindrical cells, in which the young are hatched, and, in addition, some large cells of wax for holding honey. These latter cells are nearly spherical and of nearly equal sizes, and are aggregated into an irregular mass. But the important point to notice is, that these cells are always made at that degree of nearness to each other that they would have intersected or broken into each other if the spheres had been completed; but this is never permitted, the bees building perfectly flat walls of wax between the spheres which thus tend to intersect. Hence, each cell consists of an outer spherical portion, and of two, three, or more flat surfaces, according as the cell adjoins two, three or more other cells. When one cell rests on three other cells, which, from the spheres being nearly of the same size, is very frequently and necessarily the case, the three flat surfaces are united into a pyramid; and this pyramid, as Huber has remarked, is manifestly a gross imitation of the three-sided pyramidal base of the cell of the hive-bee. As in the cells of the hive-bee, so here, the three plane surfaces in any one cell necessarily enter into the construction of three adjoining cells. It is obvious that the Melipona saves wax, and what is more important, labour, by this manner of building; for the flat walls between the adjoining cells are not double, but are of the same thickness as the outer spherical portions, and yet each flat portion forms a part of two cells. Reflecting on this case, it occurred to me that if the Melipona had made its spheres at some given distance from each other, and had made them of equal sizes and had arranged them symmetrically in a double layer, the resulting structure would have been as perfect as the comb of the hive-bee. Accordingly I wrote to Professor Miller, of Cambridge, and this geometer has kindly read over the following statement, drawn up from his information, and tells me that it is strictly correct:-- If a number of equal spheres be described with their centres placed in two parallel layers; with the centre of each sphere at the distance of radius x sqrt(2) or radius x 1.41421 (or at some lesser distance), from the centres of the six surrounding spheres in the same layer; and at the same distance from the centres of the adjoining spheres in the other and parallel layer; then, if planes of intersection between the several spheres in both layers be formed, there will result a double layer of hexagonal prisms united together by pyramidal bases formed of three rhombs; and the rhombs and the sides of the hexagonal prisms will have every angle identically the same with the best measurements which have been made of the cells of the hive-bee. But I hear from Professor Wyman, who has made numerous careful measurements, that the accuracy of the workmanship of the bee has been greatly exaggerated; so much so, that whatever the typical form of the cell may be, it is rarely, if ever, realised. Hence we may safely conclude that, if we could slightly modify the instincts already possessed by the Melipona, and in themselves not very wonderful, this bee would make a structure as wonderfully perfect as that of the hive-bee. We must suppose the Melipona to have the power of forming her cells truly spherical, and of equal sizes; and this would not be very surprising, seeing that she already does so to a certain extent, and seeing what perfectly cylindrical burrows many insects make in wood, apparently by turning round on a fixed point. We must suppose the Melipona to arrange her cells in level layers, as she already does her cylindrical cells; and we must further suppose, and this is the greatest difficulty, that she can somehow judge accurately at what distance to stand from her fellow-labourers when several are making their spheres; but she is already so far enabled to judge of distance, that she always describes her spheres so as to intersect to a certain extent; and then she unites the points of intersection by perfectly flat surfaces. By such modifications of instincts which in themselves are not very wonderful--hardly more wonderful than those which guide a bird to make its nest--I believe that the hive-bee has acquired, through natural selection, her inimitable architectural powers. But this theory can be tested by experiment. Following the example of Mr. Tegetmeier, I separated two combs, and put between them a long, thick, rectangular strip of wax: the bees instantly began to excavate minute circular pits in it; and as they deepened these little pits, they made them wider and wider until they were converted into shallow basins, appearing to the eye perfectly true or parts of a sphere, and of about the diameter of a cell. It was most interesting to observe that, wherever several bees had begun to excavate these basins near together, they had begun their work at such a distance from each other that by the time the basins had acquired the above stated width (i.e. about the width of an ordinary cell), and were in depth about one sixth of the diameter of the sphere of which they formed a part, the rims of the basins intersected or broke into each other. As soon as this occurred, the bees ceased to excavate, and began to build up flat walls of wax on the lines of intersection between the basins, so that each hexagonal prism was built upon the scalloped edge of a smooth basin, instead of on the straight edges of a three-sided pyramid as in the case of ordinary cells. I then put into the hive, instead of a thick, rectangular piece of wax, a thin and narrow, knife-edged ridge, coloured with vermilion. The bees instantly began on both sides to excavate little basins near to each other, in the same way as before; but the ridge of wax was so thin, that the bottoms of the basins, if they had been excavated to the same depth as in the former experiment, would have broken into each other from the opposite sides. The bees, however, did not suffer this to happen, and they stopped their excavations in due time; so that the basins, as soon as they had been a little deepened, came to have flat bases; and these flat bases, formed by thin little plates of the vermilion wax left ungnawed, were situated, as far as the eye could judge, exactly along the planes of imaginary intersection between the basins on the opposite side of the ridge of wax. In some parts, only small portions, in other parts, large portions of a rhombic plate were thus left between the opposed basins, but the work, from the unnatural state of things, had not been neatly performed. The bees must have worked at very nearly the same rate in circularly gnawing away and deepening the basins on both sides of the ridge of vermilion wax, in order to have thus succeeded in leaving flat plates between the basins, by stopping work at the planes of intersection. Considering how flexible thin wax is, I do not see that there is any difficulty in the bees, whilst at work on the two sides of a strip of wax, perceiving when they have gnawed the wax away to the proper thinness, and then stopping their work. In ordinary combs it has appeared to me that the bees do not always succeed in working at exactly the same rate from the opposite sides; for I have noticed half-completed rhombs at the base of a just-commenced cell, which were slightly concave on one side, where I suppose that the bees had excavated too quickly, and convex on the opposed side where the bees had worked less quickly. In one well-marked instance, I put the comb back into the hive, and allowed the bees to go on working for a short time, and again examined the cell, and I found that the rhombic plate had been completed, and had become PERFECTLY FLAT: it was absolutely impossible, from the extreme thinness of the little plate, that they could have effected this by gnawing away the convex side; and I suspect that the bees in such cases stand in the opposed cells and push and bend the ductile and warm wax (which as I have tried is easily done) into its proper intermediate plane, and thus flatten it. From the experiment of the ridge of vermilion wax we can see that, if the bees were to build for themselves a thin wall of wax, they could make their cells of the proper shape, by standing at the proper distance from each other, by excavating at the same rate, and by endeavouring to make equal spherical hollows, but never allowing the spheres to break into each other. Now bees, as may be clearly seen by examining the edge of a growing comb, do make a rough, circumferential wall or rim all round the comb; and they gnaw this away from the opposite sides, always working circularly as they deepen each cell. They do not make the whole three-sided pyramidal base of any one cell at the same time, but only that one rhombic plate which stands on the extreme growing margin, or the two plates, as the case may be; and they never complete the upper edges of the rhombic plates, until the hexagonal walls are commenced. Some of these statements differ from those made by the justly celebrated elder Huber, but I am convinced of their accuracy; and if I had space, I could show that they are conformable with my theory. Huber's statement, that the very first cell is excavated out of a little parallel-sided wall of wax, is not, as far as I have seen, strictly correct; the first commencement having always been a little hood of wax; but I will not here enter on details. We see how important a part excavation plays in the construction of the cells; but it would be a great error to suppose that the bees cannot build up a rough wall of wax in the proper position--that is, along the plane of intersection between two adjoining spheres. I have several specimens showing clearly that they can do this. Even in the rude circumferential rim or wall of wax round a growing comb, flexures may sometimes be observed, corresponding in position to the planes of the rhombic basal plates of future cells. But the rough wall of wax has in every case to be finished off, by being largely gnawed away on both sides. The manner in which the bees build is curious; they always make the first rough wall from ten to twenty times thicker than the excessively thin finished wall of the cell, which will ultimately be left. We shall understand how they work, by supposing masons first to pile up a broad ridge of cement, and then to begin cutting it away equally on both sides near the ground, till a smooth, very thin wall is left in the middle; the masons always piling up the cut-away cement, and adding fresh cement on the summit of the ridge. We shall thus have a thin wall steadily growing upward but always crowned by a gigantic coping. From all the cells, both those just commenced and those completed, being thus crowned by a strong coping of wax, the bees can cluster and crawl over the comb without injuring the delicate hexagonal walls. These walls, as Professor Miller has kindly ascertained for me, vary greatly in thickness; being, on an average of twelve measurements made near the border of the comb, 1/352 of an inch in thickness; whereas the basal rhomboidal plates are thicker, nearly in the proportion of three to two, having a mean thickness, from twenty-one measurements, of 1/229 of an inch. By the above singular manner of building, strength is continually given to the comb, with the utmost ultimate economy of wax. It seems at first to add to the difficulty of understanding how the cells are made, that a multitude of bees all work together; one bee after working a short time at one cell going to another, so that, as Huber has stated, a score of individuals work even at the commencement of the first cell. I was able practically to show this fact, by covering the edges of the hexagonal walls of a single cell, or the extreme margin of the circumferential rim of a growing comb, with an extremely thin layer of melted vermilion wax; and I invariably found that the colour was most delicately diffused by the bees--as delicately as a painter could have done it with his brush--by atoms of the coloured wax having been taken from the spot on which it had been placed, and worked into the growing edges of the cells all round. The work of construction seems to be a sort of balance struck between many bees, all instinctively standing at the same relative distance from each other, all trying to sweep equal spheres, and then building up, or leaving ungnawed, the planes of intersection between these spheres. It was really curious to note in cases of difficulty, as when two pieces of comb met at an angle, how often the bees would pull down and rebuild in different ways the same cell, sometimes recurring to a shape which they had at first rejected. When bees have a place on which they can stand in their proper positions for working--for instance, on a slip of wood, placed directly under the middle of a comb growing downwards, so that the comb has to be built over one face of the slip--in this case the bees can lay the foundations of one wall of a new hexagon, in its strictly proper place, projecting beyond the other completed cells. It suffices that the bees should be enabled to stand at their proper relative distances from each other and from the walls of the last completed cells, and then, by striking imaginary spheres, they can build up a wall intermediate between two adjoining spheres; but, as far as I have seen, they never gnaw away and finish off the angles of a cell till a large part both of that cell and of the adjoining cells has been built. This capacity in bees of laying down under certain circumstances a rough wall in its proper place between two just-commenced cells, is important, as it bears on a fact, which seems at first subversive of the foregoing theory; namely, that the cells on the extreme margin of wasp-combs are sometimes strictly hexagonal; but I have not space here to enter on this subject. Nor does there seem to me any great difficulty in a single insect (as in the case of a queen-wasp) making hexagonal cells, if she were to work alternately on the inside and outside of two or three cells commenced at the same time, always standing at the proper relative distance from the parts of the cells just begun, sweeping spheres or cylinders, and building up intermediate planes. As natural selection acts only by the accumulation of slight modifications of structure or instinct, each profitable to the individual under its conditions of life, it may reasonably be asked, how a long and graduated succession of modified architectural instincts, all tending towards the present perfect plan of construction, could have profited the progenitors of the hive-bee? I think the answer is not difficult: cells constructed like those of the bee or the wasp gain in strength, and save much in labour and space, and in the materials of which they are constructed. With respect to the formation of wax, it is known that bees are often hard pressed to get sufficient nectar; and I am informed by Mr. Tegetmeier that it has been experimentally proved that from twelve to fifteen pounds of dry sugar are consumed by a hive of bees for the secretion of a pound of wax; so that a prodigious quantity of fluid nectar must be collected and consumed by the bees in a hive for the secretion of the wax necessary for the construction of their combs. Moreover, many bees have to remain idle for many days during the process of secretion. A large store of honey is indispensable to support a large stock of bees during the winter; and the security of the hive is known mainly to depend on a large number of bees being supported. Hence the saving of wax by largely saving honey, and the time consumed in collecting the honey, must be an important element of success any family of bees. Of course the success of the species may be dependent on the number of its enemies, or parasites, or on quite distinct causes, and so be altogether independent of the quantity of honey which the bees can collect. But let us suppose that this latter circumstance determined, as it probably often has determined, whether a bee allied to our humble-bees could exist in large numbers in any country; and let us further suppose that the community lived through the winter, and consequently required a store of honey: there can in this case be no doubt that it would be an advantage to our imaginary humble-bee if a slight modification of her instincts led her to make her waxen cells near together, so as to intersect a little; for a wall in common even to two adjoining cells would save some little labour and wax. Hence, it would continually be more and more advantageous to our humble-bees, if they were to make their cells more and more regular, nearer together, and aggregated into a mass, like the cells of the Melipona; for in this case a large part of the bounding surface of each cell would serve to bound the adjoining cells, and much labour and wax would be saved. Again, from the same cause, it would be advantageous to the Melipona, if she were to make her cells closer together, and more regular in every way than at present; for then, as we have seen, the spherical surfaces would wholly disappear and be replaced by plane surfaces; and the Melipona would make a comb as perfect as that of the hive-bee. Beyond this stage of perfection in architecture, natural selection could not lead; for the comb of the hive-bee, as far as we can see, is absolutely perfect in economising labour and wax. Thus, as I believe, the most wonderful of all known instincts, that of the hive-bee, can be explained by natural selection having taken advantage of numerous, successive, slight modifications of simpler instincts; natural selection having, by slow degrees, more and more perfectly led the bees to sweep equal spheres at a given distance from each other in a double layer, and to build up and excavate the wax along the planes of intersection. The bees, of course, no more knowing that they swept their spheres at one particular distance from each other, than they know what are the several angles of the hexagonal prisms and of the basal rhombic plates; the motive power of the process of natural selection having been the construction of cells of due strength and of the proper size and shape for the larvae, this being effected with the greatest possible economy of labour and wax; that individual swarm which thus made the best cells with least labour, and least waste of honey in the secretion of wax, having succeeded best, and having transmitted their newly-acquired economical instincts to new swarms, which in their turn will have had the best chance of succeeding in the struggle for existence. OBJECTIONS TO THE THEORY OF NATURAL SELECTION AS APPLIED TO INSTINCTS: NEUTER AND STERILE INSECTS. It has been objected to the foregoing view of the origin of instincts that "the variations of structure and of instinct must have been simultaneous and accurately adjusted to each other, as a modification in the one without an immediate corresponding change in the other would have been fatal." The force of this objection rests entirely on the assumption that the changes in the instincts and structure are abrupt. To take as an illustration the case of the larger titmouse, (Parus major) alluded to in a previous chapter; this bird often holds the seeds of the yew between its feet on a branch, and hammers with its beak till it gets at the kernel. Now what special difficulty would there be in natural selection preserving all the slight individual variations in the shape of the beak, which were better and better adapted to break open the seeds, until a beak was formed, as well constructed for this purpose as that of the nuthatch, at the same time that habit, or compulsion, or spontaneous variations of taste, led the bird to become more and more of a seed-eater? In this case the beak is supposed to be slowly modified by natural selection, subsequently to, but in accordance with, slowly changing habits or taste; but let the feet of the titmouse vary and grow larger from correlation with the beak, or from any other unknown cause, and it is not improbable that such larger feet would lead the bird to climb more and more until it acquired the remarkable climbing instinct and power of the nuthatch. In this case a gradual change of structure is supposed to lead to changed instinctive habits. To take one more case: few instincts are more remarkable than that which leads the swift of the Eastern Islands to make its nest wholly of inspissated saliva. Some birds build their nests of mud, believed to be moistened with saliva; and one of the swifts of North America makes its nest (as I have seen) of sticks agglutinated with saliva, and even with flakes of this substance. Is it then very improbable that the natural selection of individual swifts, which secreted more and more saliva, should at last produce a species with instincts leading it to neglect other materials and to make its nest exclusively of inspissated saliva? And so in other cases. It must, however, be admitted that in many instances we cannot conjecture whether it was instinct or structure which first varied. No doubt many instincts of very difficult explanation could be opposed to the theory of natural selection--cases, in which we cannot see how an instinct could have originated; cases, in which no intermediate gradations are known to exist; cases of instincts of such trifling importance, that they could hardly have been acted on by natural selection; cases of instincts almost identically the same in animals so remote in the scale of nature that we cannot account for their similarity by inheritance from a common progenitor, and consequently must believe that they were independently acquired through natural selection. I will not here enter on these several cases, but will confine myself to one special difficulty, which at first appeared to me insuperable, and actually fatal to the whole theory. I allude to the neuters or sterile females in insect communities: for these neuters often differ widely in instinct and in structure from both the males and fertile females, and yet, from being sterile, they cannot propagate their kind. The subject well deserves to be discussed at great length, but I will here take only a single case, that of working or sterile ants. How the workers have been rendered sterile is a difficulty; but not much greater than that of any other striking modification of structure; for it can be shown that some insects and other articulate animals in a state of nature occasionally become sterile; and if such insects had been social, and it had been profitable to the community that a number should have been annually born capable of work, but incapable of procreation, I can see no especial difficulty in this having been effected through natural selection. But I must pass over this preliminary difficulty. The great difficulty lies in the working ants differing widely from both the males and the fertile females in structure, as in the shape of the thorax, and in being destitute of wings and sometimes of eyes, and in instinct. As far as instinct alone is concerned, the wonderful difference in this respect between the workers and the perfect females would have been better exemplified by the hive-bee. If a working ant or other neuter insect had been an ordinary animal, I should have unhesitatingly assumed that all its characters had been slowly acquired through natural selection; namely, by individuals having been born with slight profitable modifications, which were inherited by the offspring, and that these again varied and again were selected, and so onwards. But with the working ant we have an insect differing greatly from its parents, yet absolutely sterile; so that it could never have transmitted successively acquired modifications of structure or instinct to its progeny. It may well be asked how it is possible to reconcile this case with the theory of natural selection? First, let it be remembered that we have innumerable instances, both in our domestic productions and in those in a state of nature, of all sorts of differences of inherited structure which are correlated with certain ages and with either sex. We have differences correlated not only with one sex, but with that short period when the reproductive system is active, as in the nuptial plumage of many birds, and in the hooked jaws of the male salmon. We have even slight differences in the horns of different breeds of cattle in relation to an artificially imperfect state of the male sex; for oxen of certain breeds have longer horns than the oxen of other breeds, relatively to the length of the horns in both the bulls and cows of these same breeds. Hence, I can see no great difficulty in any character becoming correlated with the sterile condition of certain members of insect communities; the difficulty lies in understanding how such correlated modifications of structure could have been slowly accumulated by natural selection. This difficulty, though appearing insuperable, is lessened, or, as I believe, disappears, when it is remembered that selection may be applied to the family, as well as to the individual, and may thus gain the desired end. Breeders of cattle wish the flesh and fat to be well marbled together. An animal thus characterized has been slaughtered, but the breeder has gone with confidence to the same stock and has succeeded. Such faith may be placed in the power of selection that a breed of cattle, always yielding oxen with extraordinarily long horns, could, it is probable, be formed by carefully watching which individual bulls and cows, when matched, produced oxen with the longest horns; and yet no one ox would ever have propagated its kind. Here is a better and real illustration: According to M. Verlot, some varieties of the double annual stock, from having been long and carefully selected to the right degree, always produce a large proportion of seedlings bearing double and quite sterile flowers, but they likewise yield some single and fertile plants. These latter, by which alone the variety can be propagated, may be compared with the fertile male and female ants, and the double sterile plants with the neuters of the same community. As with the varieties of the stock, so with social insects, selection has been applied to the family, and not to the individual, for the sake of gaining a serviceable end. Hence, we may conclude that slight modifications of structure or of instinct, correlated with the sterile condition of certain members of the community, have proved advantageous; consequently the fertile males and females have flourished, and transmitted to their fertile offspring a tendency to produce sterile members with the same modifications. This process must have been repeated many times, until that prodigious amount of difference between the fertile and sterile females of the same species has been produced which we see in many social insects. But we have not as yet touched on the acme of the difficulty; namely, the fact that the neuters of several ants differ, not only from the fertile females and males, but from each other, sometimes to an almost incredible degree, and are thus divided into two or even three castes. The castes, moreover, do not generally graduate into each other, but are perfectly well defined; being as distinct from each other as are any two species of the same genus, or rather as any two genera of the same family. Thus, in Eciton, there are working and soldier neuters, with jaws and instincts extraordinarily different: in Cryptocerus, the workers of one caste alone carry a wonderful sort of shield on their heads, the use of which is quite unknown: in the Mexican Myrmecocystus, the workers of one caste never leave the nest; they are fed by the workers of another caste, and they have an enormously developed abdomen which secretes a sort of honey, supplying the place of that excreted by the aphides, or the domestic cattle as they may be called, which our European ants guard and imprison. It will indeed be thought that I have an overweening confidence in the principle of natural selection, when I do not admit that such wonderful and well-established facts at once annihilate the theory. In the simpler case of neuter insects all of one caste, which, as I believe, have been rendered different from the fertile males and females through natural selection, we may conclude from the analogy of ordinary variations, that the successive, slight, profitable modifications did not first arise in all the neuters in the same nest, but in some few alone; and that by the survival of the communities with females which produced most neuters having the advantageous modification, all the neuters ultimately came to be thus characterized. According to this view we ought occasionally to find in the same nest neuter-insects, presenting gradations of structure; and this we do find, even not rarely, considering how few neuter-insects out of Europe have been carefully examined. Mr. F. Smith has shown that the neuters of several British ants differ surprisingly from each other in size and sometimes in colour; and that the extreme forms can be linked together by individuals taken out of the same nest: I have myself compared perfect gradations of this kind. It sometimes happens that the larger or the smaller sized workers are the most numerous; or that both large and small are numerous, while those of an intermediate size are scanty in numbers. Formica flava has larger and smaller workers, with some few of intermediate size; and, in this species, as Mr. F. Smith has observed, the larger workers have simple eyes (ocelli), which, though small, can be plainly distinguished, whereas the smaller workers have their ocelli rudimentary. Having carefully dissected several specimens of these workers, I can affirm that the eyes are far more rudimentary in the smaller workers than can be accounted for merely by their proportionately lesser size; and I fully believe, though I dare not assert so positively, that the workers of intermediate size have their ocelli in an exactly intermediate condition. So that here we have two bodies of sterile workers in the same nest, differing not only in size, but in their organs of vision, yet connected by some few members in an intermediate condition. I may digress by adding, that if the smaller workers had been the most useful to the community, and those males and females had been continually selected, which produced more and more of the smaller workers, until all the workers were in this condition; we should then have had a species of ant with neuters in nearly the same condition as those of Myrmica. For the workers of Myrmica have not even rudiments of ocelli, though the male and female ants of this genus have well-developed ocelli. I may give one other case: so confidently did I expect occasionally to find gradations of important structures between the different castes of neuters in the same species, that I gladly availed myself of Mr. F. Smith's offer of numerous specimens from the same nest of the driver ant (Anomma) of West Africa. The reader will perhaps best appreciate the amount of difference in these workers by my giving, not the actual measurements, but a strictly accurate illustration: the difference was the same as if we were to see a set of workmen building a house, of whom many were five feet four inches high, and many sixteen feet high; but we must in addition suppose that the larger workmen had heads four instead of three times as big as those of the smaller men, and jaws nearly five times as big. The jaws, moreover, of the working ants of the several sizes differed wonderfully in shape, and in the form and number of the teeth. But the important fact for us is that, though the workers can be grouped into castes of different sizes, yet they graduate insensibly into each other, as does the widely-different structure of their jaws. I speak confidently on this latter point, as Sir J. Lubbock made drawings for me, with the camera lucida, of the jaws which I dissected from the workers of the several sizes. Mr. Bates, in his interesting "Naturalist on the Amazons," has described analogous cases. With these facts before me, I believe that natural selection, by acting on the fertile ants or parents, could form a species which should regularly produce neuters, all of large size with one form of jaw, or all of small size with widely different jaws; or lastly, and this is the greatest difficulty, one set of workers of one size and structure, and simultaneously another set of workers of a different size and structure; a graduated series having first been formed, as in the case of the driver ant, and then the extreme forms having been produced in greater and greater numbers, through the survival of the parents which generated them, until none with an intermediate structure were produced. An analogous explanation has been given by Mr. Wallace, of the equally complex case, of certain Malayan butterflies regularly appearing under two or even three distinct female forms; and by Fritz Muller, of certain Brazilian crustaceans likewise appearing under two widely distinct male forms. But this subject need not here be discussed. I have now explained how, I believe, the wonderful fact of two distinctly defined castes of sterile workers existing in the same nest, both widely different from each other and from their parents, has originated. We can see how useful their production may have been to a social community of ants, on the same principle that the division of labour is useful to civilised man. Ants, however, work by inherited instincts and by inherited organs or tools, while man works by acquired knowledge and manufactured instruments. But I must confess, that, with all my faith in natural selection, I should never have anticipated that this principle could have been efficient in so high a degree, had not the case of these neuter insects led me to this conclusion. I have, therefore, discussed this case, at some little but wholly insufficient length, in order to show the power of natural selection, and likewise because this is by far the most serious special difficulty which my theory has encountered. The case, also, is very interesting, as it proves that with animals, as with plants, any amount of modification may be effected by the accumulation of numerous, slight, spontaneous variations, which are in any way profitable, without exercise or habit having been brought into play. For peculiar habits, confined to the workers of sterile females, however long they might be followed, could not possibly affect the males and fertile females, which alone leave descendants. I am surprised that no one has advanced this demonstrative case of neuter insects, against the well-known doctrine of inherited habit, as advanced by Lamarck. SUMMARY. I have endeavoured in this chapter briefly to show that the mental qualities of our domestic animals vary, and that the variations are inherited. Still more briefly I have attempted to show that instincts vary slightly in a state of nature. No one will dispute that instincts are of the highest importance to each animal. Therefore, there is no real difficulty, under changing conditions of life, in natural selection accumulating to any extent slight modifications of instinct which are in any way useful. In many cases habit or use and disuse have probably come into play. I do not pretend that the facts given in this chapter strengthen in any great degree my theory; but none of the cases of difficulty, to the best of my judgment, annihilate it. On the other hand, the fact that instincts are not always absolutely perfect and are liable to mistakes; that no instinct can be shown to have been produced for the good of other animals, though animals take advantage of the instincts of others; that the canon in natural history, of "Natura non facit saltum," is applicable to instincts as well as to corporeal structure, and is plainly explicable on the foregoing views, but is otherwise inexplicable--all tend to corroborate the theory of natural selection. This theory is also strengthened by some few other facts in regard to instincts; as by that common case of closely allied, but distinct, species, when inhabiting distant parts of the world and living under considerably different conditions of life, yet often retaining nearly the same instincts. For instance, we can understand, on the principle of inheritance, how it is that the thrush of tropical South America lines its nest with mud, in the same peculiar manner as does our British thrush; how it is that the Hornbills of Africa and India have the same extraordinary instinct of plastering up and imprisoning the females in a hole in a tree, with only a small hole left in the plaster through which the males feed them and their young when hatched; how it is that the male wrens (Troglodytes) of North America, build "cock-nests," to roost in, like the males of our Kitty-wrens,--a habit wholly unlike that of any other known bird. Finally, it may not be a logical deduction, but to my imagination it is far more satisfactory to look at such instincts as the young cuckoo ejecting its foster-brothers, ants making slaves, the larvae of ichneumonidae feeding within the live bodies of caterpillars, not as specially endowed or created instincts, but as small consequences of one general law leading to the advancement of all organic beings--namely, multiply, vary, let the strongest live and the weakest die. CHAPTER IX. HYBRIDISM. Distinction between the sterility of first crosses and of hybrids--Sterility various in degree, not universal, affected by close interbreeding, removed by domestication--Laws governing the sterility of hybrids--Sterility not a special endowment, but incidental on other differences, not accumulated by natural selection--Causes of the sterility of first crosses and of hybrids--Parallelism between the effects of changed conditions of life and of crossing--Dimorphism and trimorphism--Fertility of varieties when crossed and of their mongrel offspring not universal--Hybrids and mongrels compared independently of their fertility--Summary. The view commonly entertained by naturalists is that species, when intercrossed, have been specially endowed with sterility, in order to prevent their confusion. This view certainly seems at first highly probable, for species living together could hardly have been kept distinct had they been capable of freely crossing. The subject is in many ways important for us, more especially as the sterility of species when first crossed, and that of their hybrid offspring, cannot have been acquired, as I shall show, by the preservation of successive profitable degrees of sterility. It is an incidental result of differences in the reproductive systems of the parent-species. In treating this subject, two classes of facts, to a large extent fundamentally different, have generally been confounded; namely, the sterility of species when first crossed, and the sterility of the hybrids produced from them. Pure species have of course their organs of reproduction in a perfect condition, yet when intercrossed they produce either few or no offspring. Hybrids, on the other hand, have their reproductive organs functionally impotent, as may be clearly seen in the state of the male element in both plants and animals; though the formative organs themselves are perfect in structure, as far as the microscope reveals. In the first case the two sexual elements which go to form the embryo are perfect; in the second case they are either not at all developed, or are imperfectly developed. This distinction is important, when the cause of the sterility, which is common to the two cases, has to be considered. The distinction probably has been slurred over, owing to the sterility in both cases being looked on as a special endowment, beyond the province of our reasoning powers. The fertility of varieties, that is of the forms known or believed to be descended from common parents, when crossed, and likewise the fertility of their mongrel offspring, is, with reference to my theory, of equal importance with the sterility of species; for it seems to make a broad and clear distinction between varieties and species. DEGREES OF STERILITY. First, for the sterility of species when crossed and of their hybrid offspring. It is impossible to study the several memoirs and works of those two conscientious and admirable observers, Kolreuter and Gartner, who almost devoted their lives to this subject, without being deeply impressed with the high generality of some degree of sterility. Kolreuter makes the rule universal; but then he cuts the knot, for in ten cases in which he found two forms, considered by most authors as distinct species, quite fertile together, he unhesitatingly ranks them as varieties. Gartner, also, makes the rule equally universal; and he disputes the entire fertility of Kolreuter's ten cases. But in these and in many other cases, Gartner is obliged carefully to count the seeds, in order to show that there is any degree of sterility. He always compares the maximum number of seeds produced by two species when first crossed, and the maximum produced by their hybrid offspring, with the average number produced by both pure parent-species in a state of nature. But causes of serious error here intervene: a plant, to be hybridised, must be castrated, and, what is often more important, must be secluded in order to prevent pollen being brought to it by insects from other plants. Nearly all the plants experimented on by Gartner were potted, and were kept in a chamber in his house. That these processes are often injurious to the fertility of a plant cannot be doubted; for Gartner gives in his table about a score of cases of plants which he castrated, and artificially fertilised with their own pollen, and (excluding all cases such as the Leguminosae, in which there is an acknowledged difficulty in the manipulation) half of these twenty plants had their fertility in some degree impaired. Moreover, as Gartner repeatedly crossed some forms, such as the common red and blue pimpernels (Anagallis arvensis and coerulea), which the best botanists rank as varieties, and found them absolutely sterile, we may doubt whether many species are really so sterile, when intercrossed, as he believed. It is certain, on the one hand, that the sterility of various species when crossed is so different in degree and graduates away so insensibly, and, on the other hand, that the fertility of pure species is so easily affected by various circumstances, that for all practical purposes it is most difficult to say where perfect fertility ends and sterility begins. I think no better evidence of this can be required than that the two most experienced observers who have ever lived, namely Kolreuter and Gartner, arrived at diametrically opposite conclusions in regard to some of the very same forms. It is also most instructive to compare--but I have not space here to enter on details--the evidence advanced by our best botanists on the question whether certain doubtful forms should be ranked as species or varieties, with the evidence from fertility adduced by different hybridisers, or by the same observer from experiments made during different years. It can thus be shown that neither sterility nor fertility affords any certain distinction between species and varieties. The evidence from this source graduates away, and is doubtful in the same degree as is the evidence derived from other constitutional and structural differences. In regard to the sterility of hybrids in successive generations; though Gartner was enabled to rear some hybrids, carefully guarding them from a cross with either pure parent, for six or seven, and in one case for ten generations, yet he asserts positively that their fertility never increases, but generally decreases greatly and suddenly. With respect to this decrease, it may first be noticed that when any deviation in structure or constitution is common to both parents, this is often transmitted in an augmented degree to the offspring; and both sexual elements in hybrid plants are already affected in some degree. But I believe that their fertility has been diminished in nearly all these cases by an independent cause, namely, by too close interbreeding. I have made so many experiments and collected so many facts, showing on the one hand that an occasional cross with a distinct individual or variety increases the vigour and fertility of the offspring, and on the other hand that very close interbreeding lessens their vigour and fertility, that I cannot doubt the correctness of this conclusion. Hybrids are seldom raised by experimentalists in great numbers; and as the parent-species, or other allied hybrids, generally grow in the same garden, the visits of insects must be carefully prevented during the flowering season: hence hybrids, if left to themselves, will generally be fertilised during each generation by pollen from the same flower; and this would probably be injurious to their fertility, already lessened by their hybrid origin. I am strengthened in this conviction by a remarkable statement repeatedly made by Gartner, namely, that if even the less fertile hybrids be artificially fertilised with hybrid pollen of the same kind, their fertility, notwithstanding the frequent ill effects from manipulation, sometimes decidedly increases, and goes on increasing. Now, in the process of artificial fertilisation, pollen is as often taken by chance (as I know from my own experience) from the anthers of another flower, as from the anthers of the flower itself which is to be fertilised; so that a cross between two flowers, though probably often on the same plant, would be thus effected. Moreover, whenever complicated experiments are in progress, so careful an observer as Gartner would have castrated his hybrids, and this would have insured in each generation a cross with pollen from a distinct flower, either from the same plant or from another plant of the same hybrid nature. And thus, the strange fact of an increase of fertility in the successive generations of ARTIFICIALLY FERTILISED hybrids, in contrast with those spontaneously self-fertilised, may, as I believe, be accounted for by too close interbreeding having been avoided. Now let us turn to the results arrived at by a third most experienced hybridiser, namely, the Hon. and Rev. W. Herbert. He is as emphatic in his conclusion that some hybrids are perfectly fertile--as fertile as the pure parent-species--as are Kolreuter and Gartner that some degree of sterility between distinct species is a universal law of nature. He experimented on some of the very same species as did Gartner. The difference in their results may, I think, be in part accounted for by Herbert's great horticultural skill, and by his having hot-houses at his command. Of his many important statements I will here give only a single one as an example, namely, that "every ovule in a pod of Crinum capense fertilised by C. revolutum produced a plant, which I never saw to occur in a case of its natural fecundation." So that here we have perfect, or even more than commonly perfect fertility, in a first cross between two distinct species. This case of the Crinum leads me to refer to a singular fact, namely, that individual plants of certain species of Lobelia, Verbascum and Passiflora, can easily be fertilised by the pollen from a distinct species, but not by pollen from the same plant, though this pollen can be proved to be perfectly sound by fertilising other plants or species. In the genus Hippeastrum, in Corydalis as shown by Professor Hildebrand, in various orchids as shown by Mr. Scott and Fritz Muller, all the individuals are in this peculiar condition. So that with some species, certain abnormal individuals, and in other species all the individuals, can actually be hybridised much more readily than they can be fertilised by pollen from the same individual plant! To give one instance, a bulb of Hippeastrum aulicum produced four flowers; three were fertilised by Herbert with their own pollen, and the fourth was subsequently fertilised by the pollen of a compound hybrid descended from three distinct species: the result was that "the ovaries of the three first flowers soon ceased to grow, and after a few days perished entirely, whereas the pod impregnated by the pollen of the hybrid made vigorous growth and rapid progress to maturity, and bore good seed, which vegetated freely." Mr. Herbert tried similar experiments during many years, and always with the same result. These cases serve to show on what slight and mysterious causes the lesser or greater fertility of a species sometimes depends. The practical experiments of horticulturists, though not made with scientific precision, deserve some notice. It is notorious in how complicated a manner the species of Pelargonium, Fuchsia, Calceolaria, Petunia, Rhododendron, etc., have been crossed, yet many of these hybrids seed freely. For instance, Herbert asserts that a hybrid from Calceolaria integrifolia and plantaginea, species most widely dissimilar in general habit, "reproduces itself as perfectly as if it had been a natural species from the mountains of Chile." I have taken some pains to ascertain the degree of fertility of some of the complex crosses of Rhododendrons, and I am assured that many of them are perfectly fertile. Mr. C. Noble, for instance, informs me that he raises stocks for grafting from a hybrid between Rhod. ponticum and catawbiense, and that this hybrid "seeds as freely as it is possible to imagine." Had hybrids, when fairly treated, always gone on decreasing in fertility in each successive generation, as Gartner believed to be the case, the fact would have been notorious to nurserymen. Horticulturists raise large beds of the same hybrid, and such alone are fairly treated, for by insect agency the several individuals are allowed to cross freely with each other, and the injurious influence of close interbreeding is thus prevented. Any one may readily convince himself of the efficiency of insect agency by examining the flowers of the more sterile kinds of hybrid Rhododendrons, which produce no pollen, for he will find on their stigmas plenty of pollen brought from other flowers. In regard to animals, much fewer experiments have been carefully tried than with plants. If our systematic arrangements can be trusted, that is, if the genera of animals are as distinct from each other as are the genera of plants, then we may infer that animals more widely distinct in the scale of nature can be crossed more easily than in the case of plants; but the hybrids themselves are, I think, more sterile. It should, however, be borne in mind that, owing to few animals breeding freely under confinement, few experiments have been fairly tried: for instance, the canary-bird has been crossed with nine distinct species of finches, but, as not one of these breeds freely in confinement, we have no right to expect that the first crosses between them and the canary, or that their hybrids, should be perfectly fertile. Again, with respect to the fertility in successive generations of the more fertile hybrid animals, I hardly know of an instance in which two families of the same hybrid have been raised at the same time from different parents, so as to avoid the ill effects of close interbreeding. On the contrary, brothers and sisters have usually been crossed in each successive generation, in opposition to the constantly repeated admonition of every breeder. And in this case, it is not at all surprising that the inherent sterility in the hybrids should have gone on increasing. Although I know of hardly any thoroughly well-authenticated cases of perfectly fertile hybrid animals, I have reason to believe that the hybrids from Cervulus vaginalis and Reevesii, and from Phasianus colchicus with P. torquatus, are perfectly fertile. M. Quatrefages states that the hybrids from two moths (Bombyx cynthia and arrindia) were proved in Paris to be fertile inter se for eight generations. It has lately been asserted that two such distinct species as the hare and rabbit, when they can be got to breed together, produce offspring, which are highly fertile when crossed with one of the parent-species. The hybrids from the common and Chinese geese (A. cygnoides), species which are so different that they are generally ranked in distinct genera, have often bred in this country with either pure parent, and in one single instance they have bred inter se. This was effected by Mr. Eyton, who raised two hybrids from the same parents, but from different hatches; and from these two birds he raised no less than eight hybrids (grandchildren of the pure geese) from one nest. In India, however, these cross-bred geese must be far more fertile; for I am assured by two eminently capable judges, namely Mr. Blyth and Captain Hutton, that whole flocks of these crossed geese are kept in various parts of the country; and as they are kept for profit, where neither pure parent-species exists, they must certainly be highly or perfectly fertile. With our domesticated animals, the various races when crossed together are quite fertile; yet in many cases they are descended from two or more wild species. From this fact we must conclude either that the aboriginal parent-species at first produced perfectly fertile hybrids, or that the hybrids subsequently reared under domestication became quite fertile. This latter alternative, which was first propounded by Pallas, seems by far the most probable, and can, indeed, hardly be doubted. It is, for instance, almost certain that our dogs are descended from several wild stocks; yet, with perhaps the exception of certain indigenous domestic dogs of South America, all are quite fertile together; but analogy makes me greatly doubt, whether the several aboriginal species would at first have freely bred together and have produced quite fertile hybrids. So again I have lately acquired decisive evidence that the crossed offspring from the Indian humped and common cattle are inter se perfectly fertile; and from the observations by Rutimeyer on their important osteological differences, as well as from those by Mr. Blyth on their differences in habits, voice, constitution, etc., these two forms must be regarded as good and distinct species. The same remarks may be extended to the two chief races of the pig. We must, therefore, either give up the belief of the universal sterility of species when crossed; or we must look at this sterility in animals, not as an indelible characteristic, but as one capable of being removed by domestication. Finally, considering all the ascertained facts on the intercrossing of plants and animals, it may be concluded that some degree of sterility, both in first crosses and in hybrids, is an extremely general result; but that it cannot, under our present state of knowledge, be considered as absolutely universal. LAWS GOVERNING THE STERILITY OF FIRST CROSSES AND OF HYBRIDS. We will now consider a little more in detail the laws governing the sterility of first crosses and of hybrids. Our chief object will be to see whether or not these laws indicate that species have been specially endowed with this quality, in order to prevent their crossing and blending together in utter confusion. The following conclusions are drawn up chiefly from Gartner's admirable work on the hybridisation of plants. I have taken much pains to ascertain how far they apply to animals, and, considering how scanty our knowledge is in regard to hybrid animals, I have been surprised to find how generally the same rules apply to both kingdoms. It has been already remarked, that the degree of fertility, both of first crosses and of hybrids, graduates from zero to perfect fertility. It is surprising in how many curious ways this gradation can be shown; but only the barest outline of the facts can here be given. When pollen from a plant of one family is placed on the stigma of a plant of a distinct family, it exerts no more influence than so much inorganic dust. From this absolute zero of fertility, the pollen of different species applied to the stigma of some one species of the same genus, yields a perfect gradation in the number of seeds produced, up to nearly complete or even quite complete fertility; and, as we have seen, in certain abnormal cases, even to an excess of fertility, beyond that which the plant's own pollen produces. So in hybrids themselves, there are some which never have produced, and probably never would produce, even with the pollen of the pure parents, a single fertile seed: but in some of these cases a first trace of fertility may be detected, by the pollen of one of the pure parent-species causing the flower of the hybrid to wither earlier than it otherwise would have done; and the early withering of the flower is well known to be a sign of incipient fertilisation. From this extreme degree of sterility we have self-fertilised hybrids producing a greater and greater number of seeds up to perfect fertility. The hybrids raised from two species which are very difficult to cross, and which rarely produce any offspring, are generally very sterile; but the parallelism between the difficulty of making a first cross, and the sterility of the hybrids thus produced--two classes of facts which are generally confounded together--is by no means strict. There are many cases, in which two pure species, as in the genus Verbascum, can be united with unusual facility, and produce numerous hybrid offspring, yet these hybrids are remarkably sterile. On the other hand, there are species which can be crossed very rarely, or with extreme difficulty, but the hybrids, when at last produced, are very fertile. Even within the limits of the same genus, for instance in Dianthus, these two opposite cases occur. The fertility, both of first crosses and of hybrids, is more easily affected by unfavourable conditions, than is that of pure species. But the fertility of first crosses is likewise innately variable; for it is not always the same in degree when the same two species are crossed under the same circumstances; it depends in part upon the constitution of the individuals which happen to have been chosen for the experiment. So it is with hybrids, for their degree of fertility is often found to differ greatly in the several individuals raised from seed out of the same capsule and exposed to the same conditions. By the term systematic affinity is meant, the general resemblance between species in structure and constitution. Now the fertility of first crosses, and of the hybrids produced from them, is largely governed by their systematic affinity. This is clearly shown by hybrids never having been raised between species ranked by systematists in distinct families; and on the other hand, by very closely allied species generally uniting with facility. But the correspondence between systematic affinity and the facility of crossing is by no means strict. A multitude of cases could be given of very closely allied species which will not unite, or only with extreme difficulty; and on the other hand of very distinct species which unite with the utmost facility. In the same family there may be a genus, as Dianthus, in which very many species can most readily be crossed; and another genus, as Silene, in which the most persevering efforts have failed to produce between extremely close species a single hybrid. Even within the limits of the same genus, we meet with this same difference; for instance, the many species of Nicotiana have been more largely crossed than the species of almost any other genus; but Gartner found that N. acuminata, which is not a particularly distinct species, obstinately failed to fertilise, or to be fertilised, by no less than eight other species of Nicotiana. Many analogous facts could be given. No one has been able to point out what kind or what amount of difference, in any recognisable character, is sufficient to prevent two species crossing. It can be shown that plants most widely different in habit and general appearance, and having strongly marked differences in every part of the flower, even in the pollen, in the fruit, and in the cotyledons, can be crossed. Annual and perennial plants, deciduous and evergreen trees, plants inhabiting different stations and fitted for extremely different climates, can often be crossed with ease. By a reciprocal cross between two species, I mean the case, for instance, of a female-ass being first crossed by a stallion, and then a mare by a male-ass: these two species may then be said to have been reciprocally crossed. There is often the widest possible difference in the facility of making reciprocal crosses. Such cases are highly important, for they prove that the capacity in any two species to cross is often completely independent of their systematic affinity, that is of any difference in their structure or constitution, excepting in their reproductive systems. The diversity of the result in reciprocal crosses between the same two species was long ago observed by Kolreuter. To give an instance: Mirabilis jalapa can easily be fertilised by the pollen of M. longiflora, and the hybrids thus produced are sufficiently fertile; but Kolreuter tried more than two hundred times, during eight following years, to fertilise reciprocally M. longiflora with the pollen of M. jalapa, and utterly failed. Several other equally striking cases could be given. Thuret has observed the same fact with certain sea-weeds or Fuci. Gartner, moreover, found that this difference of facility in making reciprocal crosses is extremely common in a lesser degree. He has observed it even between closely related forms (as Matthiola annua and glabra) which many botanists rank only as varieties. It is also a remarkable fact that hybrids raised from reciprocal crosses, though of course compounded of the very same two species, the one species having first been used as the father and then as the mother, though they rarely differ in external characters, yet generally differ in fertility in a small, and occasionally in a high degree. Several other singular rules could be given from Gartner: for instance, some species have a remarkable power of crossing with other species; other species of the same genus have a remarkable power of impressing their likeness on their hybrid offspring; but these two powers do not at all necessarily go together. There are certain hybrids which, instead of having, as is usual, an intermediate character between their two parents, always closely resemble one of them; and such hybrids, though externally so like one of their pure parent-species, are with rare exceptions extremely sterile. So again among hybrids which are usually intermediate in structure between their parents, exceptional and abnormal individuals sometimes are born, which closely resemble one of their pure parents; and these hybrids are almost always utterly sterile, even when the other hybrids raised from seed from the same capsule have a considerable degree of fertility. These facts show how completely the fertility of a hybrid may be independent of its external resemblance to either pure parent. Considering the several rules now given, which govern the fertility of first crosses and of hybrids, we see that when forms, which must be considered as good and distinct species, are united, their fertility graduates from zero to perfect fertility, or even to fertility under certain conditions in excess; that their fertility, besides being eminently susceptible to favourable and unfavourable conditions, is innately variable; that it is by no means always the same in degree in the first cross and in the hybrids produced from this cross; that the fertility of hybrids is not related to the degree in which they resemble in external appearance either parent; and lastly, that the facility of making a first cross between any two species is not always governed by their systematic affinity or degree of resemblance to each other. This latter statement is clearly proved by the difference in the result of reciprocal crosses between the same two species, for, according as the one species or the other is used as the father or the mother, there is generally some difference, and occasionally the widest possible difference, in the facility of effecting an union. The hybrids, moreover, produced from reciprocal crosses often differ in fertility. Now do these complex and singular rules indicate that species have been endowed with sterility simply to prevent their becoming confounded in nature? I think not. For why should the sterility be so extremely different in degree, when various species are crossed, all of which we must suppose it would be equally important to keep from blending together? Why should the degree of sterility be innately variable in the individuals of the same species? Why should some species cross with facility and yet produce very sterile hybrids; and other species cross with extreme difficulty, and yet produce fairly fertile hybrids? Why should there often be so great a difference in the result of a reciprocal cross between the same two species? Why, it may even be asked, has the production of hybrids been permitted? To grant to species the special power of producing hybrids, and then to stop their further propagation by different degrees of sterility, not strictly related to the facility of the first union between their parents, seems a strange arrangement. The foregoing rules and facts, on the other hand, appear to me clearly to indicate that the sterility, both of first crosses and of hybrids, is simply incidental or dependent on unknown differences in their reproductive systems; the differences being of so peculiar and limited a nature, that, in reciprocal crosses between the same two species, the male sexual element of the one will often freely act on the female sexual element of the other, but not in a reversed direction. It will be advisable to explain a little more fully, by an example, what I mean by sterility being incidental on other differences, and not a specially endowed quality. As the capacity of one plant to be grafted or budded on another is unimportant for their welfare in a state of nature, I presume that no one will suppose that this capacity is a SPECIALLY endowed quality, but will admit that it is incidental on differences in the laws of growth of the two plants. We can sometimes see the reason why one tree will not take on another from differences in their rate of growth, in the hardness of their wood, in the period of the flow or nature of their sap, etc.; but in a multitude of cases we can assign no reason whatever. Great diversity in the size of two plants, one being woody and the other herbaceous, one being evergreen and the other deciduous, and adaptation to widely different climates, does not always prevent the two grafting together. As in hybridisation, so with grafting, the capacity is limited by systematic affinity, for no one has been able to graft together trees belonging to quite distinct families; and, on the other hand, closely allied species and varieties of the same species, can usually, but not invariably, be grafted with ease. But this capacity, as in hybridisation, is by no means absolutely governed by systematic affinity. Although many distinct genera within the same family have been grafted together, in other cases species of the same genus will not take on each other. The pear can be grafted far more readily on the quince, which is ranked as a distinct genus, than on the apple, which is a member of the same genus. Even different varieties of the pear take with different degrees of facility on the quince; so do different varieties of the apricot and peach on certain varieties of the plum. As Gartner found that there was sometimes an innate difference in different INDIVIDUALS of the same two species in crossing; so Sagaret believes this to be the case with different individuals of the same two species in being grafted together. As in reciprocal crosses, the facility of effecting an union is often very far from equal, so it sometimes is in grafting. The common gooseberry, for instance, cannot be grafted on the currant, whereas the currant will take, though with difficulty, on the gooseberry. We have seen that the sterility of hybrids which have their reproductive organs in an imperfect condition, is a different case from the difficulty of uniting two pure species, which have their reproductive organs perfect; yet these two distinct classes of cases run to a large extent parallel. Something analogous occurs in grafting; for Thouin found that three species of Robinia, which seeded freely on their own roots, and which could be grafted with no great difficulty on a fourth species, when thus grafted were rendered barren. On the other hand, certain species of Sorbus, when grafted on other species, yielded twice as much fruit as when on their own roots. We are reminded by this latter fact of the extraordinary cases of Hippeastrum, Passiflora, etc., which seed much more freely when fertilised with the pollen of a distinct species than when fertilised with pollen from the same plant. We thus see that, although there is a clear and great difference between the mere adhesion of grafted stocks and the union of the male and female elements in the act of reproduction, yet that there is a rude degree of parallelism in the results of grafting and of crossing distinct species. And as we must look at the curious and complex laws governing the facility with which trees can be grafted on each other as incidental on unknown differences in their vegetative systems, so I believe that the still more complex laws governing the facility of first crosses are incidental on unknown differences in their reproductive systems. These differences in both cases follow, to a certain extent, as might have been expected, systematic affinity, by which term every kind of resemblance and dissimilarity between organic beings is attempted to be expressed. The facts by no means seem to indicate that the greater or lesser difficulty of either grafting or crossing various species has been a special endowment; although in the case of crossing, the difficulty is as important for the endurance and stability of specific forms as in the case of grafting it is unimportant for their welfare. ORIGIN AND CAUSES OF THE STERILITY OF FIRST CROSSES AND OF HYBRIDS. At one time it appeared to me probable, as it has to others, that the sterility of first crosses and of hybrids might have been slowly acquired through the natural selection of slightly lessened degrees of fertility, which, like any other variation, spontaneously appeared in certain individuals of one variety when crossed with those of another variety. For it would clearly be advantageous to two varieties or incipient species if they could be kept from blending, on the same principle that, when man is selecting at the same time two varieties, it is necessary that he should keep them separate. In the first place, it may be remarked that species inhabiting distinct regions are often sterile when crossed; now it could clearly have been of no advantage to such separated species to have been rendered mutually sterile, and consequently this could not have been effected through natural selection; but it may perhaps be argued, that, if a species was rendered sterile with some one compatriot, sterility with other species would follow as a necessary contingency. In the second place, it is almost as much opposed to the theory of natural selection as to that of special creation, that in reciprocal crosses the male element of one form should have been rendered utterly impotent on a second form, while at the same time the male element of this second form is enabled freely to fertilise the first form; for this peculiar state of the reproductive system could hardly have been advantageous to either species. In considering the probability of natural selection having come into action, in rendering species mutually sterile, the greatest difficulty will be found to lie in the existence of many graduated steps, from slightly lessened fertility to absolute sterility. It may be admitted that it would profit an incipient species, if it were rendered in some slight degree sterile when crossed with its parent form or with some other variety; for thus fewer bastardised and deteriorated offspring would be produced to commingle their blood with the new species in process of formation. But he who will take the trouble to reflect on the steps by which this first degree of sterility could be increased through natural selection to that high degree which is common with so many species, and which is universal with species which have been differentiated to a generic or family rank, will find the subject extraordinarily complex. After mature reflection, it seems to me that this could not have been effected through natural selection. Take the case of any two species which, when crossed, produced few and sterile offspring; now, what is there which could favour the survival of those individuals which happened to be endowed in a slightly higher degree with mutual infertility, and which thus approached by one small step towards absolute sterility? Yet an advance of this kind, if the theory of natural selection be brought to bear, must have incessantly occurred with many species, for a multitude are mutually quite barren. With sterile neuter insects we have reason to believe that modifications in their structure and fertility have been slowly accumulated by natural selection, from an advantage having been thus indirectly given to the community to which they belonged over other communities of the same species; but an individual animal not belonging to a social community, if rendered slightly sterile when crossed with some other variety, would not thus itself gain any advantage or indirectly give any advantage to the other individuals of the same variety, thus leading to their preservation. But it would be superfluous to discuss this question in detail: for with plants we have conclusive evidence that the sterility of crossed species must be due to some principle, quite independent of natural selection. Both Gartner and Kolreuter have proved that in genera including numerous species, a series can be formed from species which when crossed yield fewer and fewer seeds, to species which never produce a single seed, but yet are affected by the pollen of certain other species, for the germen swells. It is here manifestly impossible to select the more sterile individuals, which have already ceased to yield seeds; so that this acme of sterility, when the germen alone is effected, cannot have been gained through selection; and from the laws governing the various grades of sterility being so uniform throughout the animal and vegetable kingdoms, we may infer that the cause, whatever it may be, is the same or nearly the same in all cases. We will now look a little closer at the probable nature of the differences between species which induce sterility in first crosses and in hybrids. In the case of first crosses, the greater or less difficulty in effecting a union and in obtaining offspring apparently depends on several distinct causes. There must sometimes be a physical impossibility in the male element reaching the ovule, as would be the case with a plant having a pistil too long for the pollen-tubes to reach the ovarium. It has also been observed that when the pollen of one species is placed on the stigma of a distantly allied species, though the pollen-tubes protrude, they do not penetrate the stigmatic surface. Again, the male element may reach the female element, but be incapable of causing an embryo to be developed, as seems to have been the case with some of Thuret's experiments on Fuci. No explanation can be given of these facts, any more than why certain trees cannot be grafted on others. Lastly, an embryo may be developed, and then perish at an early period. This latter alternative has not been sufficiently attended to; but I believe, from observations communicated to me by Mr. Hewitt, who has had great experience in hybridising pheasants and fowls, that the early death of the embryo is a very frequent cause of sterility in first crosses. Mr. Salter has recently given the results of an examination of about 500 eggs produced from various crosses between three species of Gallus and their hybrids; the majority of these eggs had been fertilised; and in the majority of the fertilised eggs, the embryos had either been partially developed and had then perished, or had become nearly mature, but the young chickens had been unable to break through the shell. Of the chickens which were born, more than four-fifths died within the first few days, or at latest weeks, "without any obvious cause, apparently from mere inability to live;" so that from the 500 eggs only twelve chickens were reared. With plants, hybridized embryos probably often perish in a like manner; at least it is known that hybrids raised from very distinct species are sometimes weak and dwarfed, and perish at an early age; of which fact Max Wichura has recently given some striking cases with hybrid willows. It may be here worth noticing that in some cases of parthenogenesis, the embryos within the eggs of silk moths which had not been fertilised, pass through their early stages of development and then perish like the embryos produced by a cross between distinct species. Until becoming acquainted with these facts, I was unwilling to believe in the frequent early death of hybrid embryos; for hybrids, when once born, are generally healthy and long-lived, as we see in the case of the common mule. Hybrids, however, are differently circumstanced before and after birth: when born and living in a country where their two parents live, they are generally placed under suitable conditions of life. But a hybrid partakes of only half of the nature and constitution of its mother; it may therefore, before birth, as long as it is nourished within its mother's womb, or within the egg or seed produced by the mother, be exposed to conditions in some degree unsuitable, and consequently be liable to perish at an early period; more especially as all very young beings are eminently sensitive to injurious or unnatural conditions of life. But after all, the cause more probably lies in some imperfection in the original act of impregnation, causing the embryo to be imperfectly developed, rather than in the conditions to which it is subsequently exposed. In regard to the sterility of hybrids, in which the sexual elements are imperfectly developed, the case is somewhat different. I have more than once alluded to a large body of facts showing that, when animals and plants are removed from their natural conditions, they are extremely liable to have their reproductive systems seriously affected. This, in fact, is the great bar to the domestication of animals. Between the sterility thus superinduced and that of hybrids, there are many points of similarity. In both cases the sterility is independent of general health, and is often accompanied by excess of size or great luxuriance. In both cases the sterility occurs in various degrees; in both, the male element is the most liable to be affected; but sometimes the female more than the male. In both, the tendency goes to a certain extent with systematic affinity, for whole groups of animals and plants are rendered impotent by the same unnatural conditions; and whole groups of species tend to produce sterile hybrids. On the other hand, one species in a group will sometimes resist great changes of conditions with unimpaired fertility; and certain species in a group will produce unusually fertile hybrids. No one can tell till he tries, whether any particular animal will breed under confinement, or any exotic plant seed freely under culture; nor can he tell till he tries, whether any two species of a genus will produce more or less sterile hybrids. Lastly, when organic beings are placed during several generations under conditions not natural to them, they are extremely liable to vary, which seems to be partly due to their reproductive systems having been specially affected, though in a lesser degree than when sterility ensues. So it is with hybrids, for their offspring in successive generations are eminently liable to vary, as every experimentalist has observed. Thus we see that when organic beings are placed under new and unnatural conditions, and when hybrids are produced by the unnatural crossing of two species, the reproductive system, independently of the general state of health, is affected in a very similar manner. In the one case, the conditions of life have been disturbed, though often in so slight a degree as to be inappreciable by us; in the other case, or that of hybrids, the external conditions have remained the same, but the organisation has been disturbed by two distinct structures and constitutions, including of course the reproductive systems, having been blended into one. For it is scarcely possible that two organisations should be compounded into one, without some disturbance occurring in the development, or periodical action, or mutual relations of the different parts and organs one to another or to the conditions of life. When hybrids are able to breed inter se, they transmit to their offspring from generation to generation the same compounded organisation, and hence we need not be surprised that their sterility, though in some degree variable, does not diminish; it is even apt to increase, this being generally the result, as before explained, of too close interbreeding. The above view of the sterility of hybrids being caused by two constitutions being compounded into one has been strongly maintained by Max Wichura. It must, however, be owned that we cannot understand, on the above or any other view, several facts with respect to the sterility of hybrids; for instance, the unequal fertility of hybrids produced from reciprocal crosses; or the increased sterility in those hybrids which occasionally and exceptionally resemble closely either pure parent. Nor do I pretend that the foregoing remarks go to the root of the matter: no explanation is offered why an organism, when placed under unnatural conditions, is rendered sterile. All that I have attempted to show is, that in two cases, in some respects allied, sterility is the common result--in the one case from the conditions of life having been disturbed, in the other case from the organisation having been disturbed by two organisations being compounded into one. A similar parallelism holds good with an allied yet very different class of facts. It is an old and almost universal belief, founded on a considerable body of evidence, which I have elsewhere given, that slight changes in the conditions of life are beneficial to all living things. We see this acted on by farmers and gardeners in their frequent exchanges of seed, tubers, etc., from one soil or climate to another, and back again. During the convalescence of animals, great benefit is derived from almost any change in their habits of life. Again, both with plants and animals, there is the clearest evidence that a cross between individuals of the same species, which differ to a certain extent, gives vigour and fertility to the offspring; and that close interbreeding continued during several generations between the nearest relations, if these be kept under the same conditions of life, almost always leads to decreased size, weakness, or sterility. Hence it seems that, on the one hand, slight changes in the conditions of life benefit all organic beings, and on the other hand, that slight crosses, that is, crosses between the males and females of the same species, which have been subjected to slightly different conditions, or which have slightly varied, give vigour and fertility to the offspring. But, as we have seen, organic beings long habituated to certain uniform conditions under a state of nature, when subjected, as under confinement, to a considerable change in their conditions, very frequently are rendered more or less sterile; and we know that a cross between two forms that have become widely or specifically different, produce hybrids which are almost always in some degree sterile. I am fully persuaded that this double parallelism is by no means an accident or an illusion. He who is able to explain why the elephant, and a multitude of other animals, are incapable of breeding when kept under only partial confinement in their native country, will be able to explain the primary cause of hybrids being so generally sterile. He will at the same time be able to explain how it is that the races of some of our domesticated animals, which have often been subjected to new and not uniform conditions, are quite fertile together, although they are descended from distinct species, which would probably have been sterile if aboriginally crossed. The above two parallel series of facts seem to be connected together by some common but unknown bond, which is essentially related to the principle of life; this principle, according to Mr. Herbert Spencer, being that life depends on, or consists in, the incessant action and reaction of various forces, which, as throughout nature, are always tending towards an equilibrium; and when this tendency is slightly disturbed by any change, the vital forces gain in power. RECIPROCAL DIMORPHISM AND TRIMORPHISM. This subject may be here briefly discussed, and will be found to throw some light on hybridism. Several plants belonging to distinct orders present two forms, which exist in about equal numbers and which differ in no respect except in their reproductive organs; one form having a long pistil with short stamens, the other a short pistil with long stamens; the two having differently sized pollen-grains. With trimorphic plants there are three forms likewise differing in the lengths of their pistils and stamens, in the size and colour of the pollen-grains, and in some other respects; and as in each of the three forms there are two sets of stamens, the three forms possess altogether six sets of stamens and three kinds of pistils. These organs are so proportioned in length to each other that half the stamens in two of the forms stand on a level with the stigma of the third form. Now I have shown, and the result has been confirmed by other observers, that in order to obtain full fertility with these plants, it is necessary that the stigma of the one form should be fertilised by pollen taken from the stamens of corresponding height in another form. So that with dimorphic species two unions, which may be called legitimate, are fully fertile; and two, which may be called illegitimate, are more or less infertile. With trimorphic species six unions are legitimate, or fully fertile, and twelve are illegitimate, or more or less infertile. The infertility which may be observed in various dimorphic and trimorphic plants, when they are illegitimately fertilised, that is by pollen taken from stamens not corresponding in height with the pistil, differs much in degree, up to absolute and utter sterility; just in the same manner as occurs in crossing distinct species. As the degree of sterility in the latter case depends in an eminent degree on the conditions of life being more or less favourable, so I have found it with illegitimate unions. It is well known that if pollen of a distinct species be placed on the stigma of a flower, and its own pollen be afterwards, even after a considerable interval of time, placed on the same stigma, its action is so strongly prepotent that it generally annihilates the effect of the foreign pollen; so it is with the pollen of the several forms of the same species, for legitimate pollen is strongly prepotent over illegitimate pollen, when both are placed on the same stigma. I ascertained this by fertilising several flowers, first illegitimately, and twenty-four hours afterwards legitimately, with pollen taken from a peculiarly coloured variety, and all the seedlings were similarly coloured; this shows that the legitimate pollen, though applied twenty-four hours subsequently, had wholly destroyed or prevented the action of the previously applied illegitimate pollen. Again, as in making reciprocal crosses between the same two species, there is occasionally a great difference in the result, so the same thing occurs with trimorphic plants; for instance, the mid-styled form of Lythrum salicaria was illegitimately fertilised with the greatest ease by pollen from the longer stamens of the short-styled form, and yielded many seeds; but the latter form did not yield a single seed when fertilised by the longer stamens of the mid-styled form. In all these respects, and in others which might be added, the forms of the same undoubted species, when illegitimately united, behave in exactly the same manner as do two distinct species when crossed. This led me carefully to observe during four years many seedlings, raised from several illegitimate unions. The chief result is that these illegitimate plants, as they may be called, are not fully fertile. It is possible to raise from dimorphic species, both long-styled and short-styled illegitimate plants, and from trimorphic plants all three illegitimate forms. These can then be properly united in a legitimate manner. When this is done, there is no apparent reason why they should not yield as many seeds as did their parents when legitimately fertilised. But such is not the case. They are all infertile, in various degrees; some being so utterly and incurably sterile that they did not yield during four seasons a single seed or even seed-capsule. The sterility of these illegitimate plants, when united with each other in a legitimate manner, may be strictly compared with that of hybrids when crossed inter se. If, on the other hand, a hybrid is crossed with either pure parent-species, the sterility is usually much lessened: and so it is when an illegitimate plant is fertilised by a legitimate plant. In the same manner as the sterility of hybrids does not always run parallel with the difficulty of making the first cross between the two parent-species, so that sterility of certain illegitimate plants was unusually great, while the sterility of the union from which they were derived was by no means great. With hybrids raised from the same seed-capsule the degree of sterility is innately variable, so it is in a marked manner with illegitimate plants. Lastly, many hybrids are profuse and persistent flowerers, while other and more sterile hybrids produce few flowers, and are weak, miserable dwarfs; exactly similar cases occur with the illegitimate offspring of various dimorphic and trimorphic plants. Altogether there is the closest identity in character and behaviour between illegitimate plants and hybrids. It is hardly an exaggeration to maintain that illegitimate plants are hybrids, produced within the limits of the same species by the improper union of certain forms, while ordinary hybrids are produced from an improper union between so-called distinct species. We have also already seen that there is the closest similarity in all respects between first illegitimate unions and first crosses between distinct species. This will perhaps be made more fully apparent by an illustration; we may suppose that a botanist found two well-marked varieties (and such occur) of the long-styled form of the trimorphic Lythrum salicaria, and that he determined to try by crossing whether they were specifically distinct. He would find that they yielded only about one-fifth of the proper number of seed, and that they behaved in all the other above specified respects as if they had been two distinct species. But to make the case sure, he would raise plants from his supposed hybridised seed, and he would find that the seedlings were miserably dwarfed and utterly sterile, and that they behaved in all other respects like ordinary hybrids. He might then maintain that he had actually proved, in accordance with the common view, that his two varieties were as good and as distinct species as any in the world; but he would be completely mistaken. The facts now given on dimorphic and trimorphic plants are important, because they show us, first, that the physiological test of lessened fertility, both in first crosses and in hybrids, is no safe criterion of specific distinction; secondly, because we may conclude that there is some unknown bond which connects the infertility of illegitimate unions with that of their illegitimate offspring, and we are led to extend the same view to first crosses and hybrids; thirdly, because we find, and this seems to me of especial importance, that two or three forms of the same species may exist and may differ in no respect whatever, either in structure or in constitution, relatively to external conditions, and yet be sterile when united in certain ways. For we must remember that it is the union of the sexual elements of individuals of the same form, for instance, of two long-styled forms, which results in sterility; while it is the union of the sexual elements proper to two distinct forms which is fertile. Hence the case appears at first sight exactly the reverse of what occurs, in the ordinary unions of the individuals of the same species and with crosses between distinct species. It is, however, doubtful whether this is really so; but I will not enlarge on this obscure subject. We may, however, infer as probable from the consideration of dimorphic and trimorphic plants, that the sterility of distinct species when crossed and of their hybrid progeny, depends exclusively on the nature of their sexual elements, and not on any difference in their structure or general constitution. We are also led to this same conclusion by considering reciprocal crosses, in which the male of one species cannot be united, or can be united with great difficulty, with the female of a second species, while the converse cross can be effected with perfect facility. That excellent observer, Gartner, likewise concluded that species when crossed are sterile owing to differences confined to their reproductive systems. FERTILITY OF VARIETIES WHEN CROSSED, AND OF THEIR MONGREL OFFSPRING, NOT UNIVERSAL. It may be urged as an overwhelming argument that there must be some essential distinction between species and varieties inasmuch as the latter, however much they may differ from each other in external appearance, cross with perfect facility, and yield perfectly fertile offspring. With some exceptions, presently to be given, I fully admit that this is the rule. But the subject is surrounded by difficulties, for, looking to varieties produced under nature, if two forms hitherto reputed to be varieties be found in any degree sterile together, they are at once ranked by most naturalists as species. For instance, the blue and red pimpernel, which are considered by most botanists as varieties, are said by Gartner to be quite sterile when crossed, and he consequently ranks them as undoubted species. If we thus argue in a circle, the fertility of all varieties produced under nature will assuredly have to be granted. If we turn to varieties, produced, or supposed to have been produced, under domestication, we are still involved in some doubt. For when it is stated, for instance, that certain South American indigenous domestic dogs do not readily unite with European dogs, the explanation which will occur to everyone, and probably the true one, is that they are descended from aboriginally distinct species. Nevertheless the perfect fertility of so many domestic races, differing widely from each other in appearance, for instance, those of the pigeon, or of the cabbage, is a remarkable fact; more especially when we reflect how many species there are, which, though resembling each other most closely, are utterly sterile when intercrossed. Several considerations, however, render the fertility of domestic varieties less remarkable. In the first place, it may be observed that the amount of external difference between two species is no sure guide to their degree of mutual sterility, so that similar differences in the case of varieties would be no sure guide. It is certain that with species the cause lies exclusively in differences in their sexual constitution. Now the varying conditions to which domesticated animals and cultivated plants have been subjected, have had so little tendency towards modifying the reproductive system in a manner leading to mutual sterility, that we have good grounds for admitting the directly opposite doctrine of Pallas, namely, that such conditions generally eliminate this tendency; so that the domesticated descendants of species, which in their natural state probably would have been in some degree sterile when crossed, become perfectly fertile together. With plants, so far is cultivation from giving a tendency towards sterility between distinct species, that in several well-authenticated cases already alluded to, certain plants have been affected in an opposite manner, for they have become self-impotent, while still retaining the capacity of fertilising, and being fertilised by, other species. If the Pallasian doctrine of the elimination of sterility through long-continued domestication be admitted, and it can hardly be rejected, it becomes in the highest degree improbable that similar conditions long-continued should likewise induce this tendency; though in certain cases, with species having a peculiar constitution, sterility might occasionally be thus caused. Thus, as I believe, we can understand why, with domesticated animals, varieties have not been produced which are mutually sterile; and why with plants only a few such cases, immediately to be given, have been observed. The real difficulty in our present subject is not, as it appears to me, why domestic varieties have not become mutually infertile when crossed, but why this has so generally occurred with natural varieties, as soon as they have been permanently modified in a sufficient degree to take rank as species. We are far from precisely knowing the cause; nor is this surprising, seeing how profoundly ignorant we are in regard to the normal and abnormal action of the reproductive system. But we can see that species, owing to their struggle for existence with numerous competitors, will have been exposed during long periods of time to more uniform conditions, than have domestic varieties; and this may well make a wide difference in the result. For we know how commonly wild animals and plants, when taken from their natural conditions and subjected to captivity, are rendered sterile; and the reproductive functions of organic beings which have always lived under natural conditions would probably in like manner be eminently sensitive to the influence of an unnatural cross. Domesticated productions, on the other hand, which, as shown by the mere fact of their domestication, were not originally highly sensitive to changes in their conditions of life, and which can now generally resist with undiminished fertility repeated changes of conditions, might be expected to produce varieties, which would be little liable to have their reproductive powers injuriously affected by the act of crossing with other varieties which had originated in a like manner. I have as yet spoken as if the varieties of the same species were invariably fertile when intercrossed. But it is impossible to resist the evidence of the existence of a certain amount of sterility in the few following cases, which I will briefly abstract. The evidence is at least as good as that from which we believe in the sterility of a multitude of species. The evidence is also derived from hostile witnesses, who in all other cases consider fertility and sterility as safe criterions of specific distinction. Gartner kept, during several years, a dwarf kind of maize with yellow seeds, and a tall variety with red seeds growing near each other in his garden; and although these plants have separated sexes, they never naturally crossed. He then fertilised thirteen flowers of the one kind with pollen of the other; but only a single head produced any seed, and this one head produced only five grains. Manipulation in this case could not have been injurious, as the plants have separated sexes. No one, I believe, has suspected that these varieties of maize are distinct species; and it is important to notice that the hybrid plants thus raised were themselves PERFECTLY fertile; so that even Gartner did not venture to consider the two varieties as specifically distinct. Girou de Buzareingues crossed three varieties of gourd, which like the maize has separated sexes, and he asserts that their mutual fertilisation is by so much the less easy as their differences are greater. How far these experiments may be trusted, I know not; but the forms experimented on are ranked by Sagaret, who mainly founds his classification by the test of infertility, as varieties, and Naudin has come to the same conclusion. The following case is far more remarkable, and seems at first incredible; but it is the result of an astonishing number of experiments made during many years on nine species of Verbascum, by so good an observer and so hostile a witness as Gartner: namely, that the yellow and white varieties when crossed produce less seed than the similarly coloured varieties of the same species. Moreover, he asserts that, when yellow and white varieties of one species are crossed with yellow and white varieties of a DISTINCT species, more seed is produced by the crosses between the similarly coloured flowers, than between those which are differently coloured. Mr. Scott also has experimented on the species and varieties of Verbascum; and although unable to confirm Gartner's results on the crossing of the distinct species, he finds that the dissimilarly coloured varieties of the same species yield fewer seeds, in the proportion of eighty-six to 100, than the similarly coloured varieties. Yet these varieties differ in no respect, except in the colour of their flowers; and one variety can sometimes be raised from the seed of another. Kolreuter, whose accuracy has been confirmed by every subsequent observer, has proved the remarkable fact that one particular variety of the common tobacco was more fertile than the other varieties, when crossed with a widely distinct species. He experimented on five forms which are commonly reputed to be varieties, and which he tested by the severest trial, namely, by reciprocal crosses, and he found their mongrel offspring perfectly fertile. But one of these five varieties, when used either as the father or mother, and crossed with the Nicotiana glutinosa, always yielded hybrids not so sterile as those which were produced from the four other varieties when crossed with N. glutinosa. Hence the reproductive system of this one variety must have been in some manner and in some degree modified. From these facts it can no longer be maintained that varieties when crossed are invariably quite fertile. From the great difficulty of ascertaining the infertility of varieties in a state of nature, for a supposed variety, if proved to be infertile in any degree, would almost universally be ranked as a species; from man attending only to external characters in his domestic varieties, and from such varieties not having been exposed for very long periods to uniform conditions of life; from these several considerations we may conclude that fertility does not constitute a fundamental distinction between varieties and species when crossed. The general sterility of crossed species may safely be looked at, not as a special acquirement or endowment, but as incidental on changes of an unknown nature in their sexual elements. HYBRIDS AND MONGRELS COMPARED, INDEPENDENTLY OF THEIR FERTILITY. Independently of the question of fertility, the offspring of species and of varieties when crossed may be compared in several other respects. Gartner, whose strong wish it was to draw a distinct line between species and varieties, could find very few, and, as it seems to me, quite unimportant differences between the so-called hybrid offspring of species, and the so-called mongrel offspring of varieties. And, on the other hand, they agree most closely in many important respects. I shall here discuss this subject with extreme brevity. The most important distinction is, that in the first generation mongrels are more variable than hybrids; but Gartner admits that hybrids from species which have long been cultivated are often variable in the first generation; and I have myself seen striking instances of this fact. Gartner further admits that hybrids between very closely allied species are more variable than those from very distinct species; and this shows that the difference in the degree of variability graduates away. When mongrels and the more fertile hybrids are propagated for several generations, an extreme amount of variability in the offspring in both cases is notorious; but some few instances of both hybrids and mongrels long retaining a uniform character could be given. The variability, however, in the successive generations of mongrels is, perhaps, greater than in hybrids. This greater variability in mongrels than in hybrids does not seem at all surprising. For the parents of mongrels are varieties, and mostly domestic varieties (very few experiments having been tried on natural varieties), and this implies that there has been recent variability; which would often continue and would augment that arising from the act of crossing. The slight variability of hybrids in the first generation, in contrast with that in the succeeding generations, is a curious fact and deserves attention. For it bears on the view which I have taken of one of the causes of ordinary variability; namely, that the reproductive system, from being eminently sensitive to changed conditions of life, fails under these circumstances to perform its proper function of producing offspring closely similar in all respects to the parent-form. Now, hybrids in the first generation are descended from species (excluding those long cultivated) which have not had their reproductive systems in any way affected, and they are not variable; but hybrids themselves have their reproductive systems seriously affected, and their descendants are highly variable. But to return to our comparison of mongrels and hybrids: Gartner states that mongrels are more liable than hybrids to revert to either parent form; but this, if it be true, is certainly only a difference in degree. Moreover, Gartner expressly states that the hybrids from long cultivated plants are more subject to reversion than hybrids from species in their natural state; and this probably explains the singular difference in the results arrived at by different observers. Thus Max Wichura doubts whether hybrids ever revert to their parent forms, and he experimented on uncultivated species of willows, while Naudin, on the other hand, insists in the strongest terms on the almost universal tendency to reversion in hybrids, and he experimented chiefly on cultivated plants. Gartner further states that when any two species, although most closely allied to each other, are crossed with a third species, the hybrids are widely different from each other; whereas if two very distinct varieties of one species are crossed with another species, the hybrids do not differ much. But this conclusion, as far as I can make out, is founded on a single experiment; and seems directly opposed to the results of several experiments made by Kolreuter. Such alone are the unimportant differences which Gartner is able to point out between hybrid and mongrel plants. On the other hand, the degrees and kinds of resemblance in mongrels and in hybrids to their respective parents, more especially in hybrids produced from nearly related species, follow, according to Gartner the same laws. When two species are crossed, one has sometimes a prepotent power of impressing its likeness on the hybrid. So I believe it to be with varieties of plants; and with animals, one variety certainly often has this prepotent power over another variety. Hybrid plants produced from a reciprocal cross generally resemble each other closely, and so it is with mongrel plants from a reciprocal cross. Both hybrids and mongrels can be reduced to either pure parent form, by repeated crosses in successive generations with either parent. These several remarks are apparently applicable to animals; but the subject is here much complicated, partly owing to the existence of secondary sexual characters; but more especially owing to prepotency in transmitting likeness running more strongly in one sex than in the other, both when one species is crossed with another and when one variety is crossed with another variety. For instance, I think those authors are right who maintain that the ass has a prepotent power over the horse, so that both the mule and the hinny resemble more closely the ass than the horse; but that the prepotency runs more strongly in the male than in the female ass, so that the mule, which is an offspring of the male ass and mare, is more like an ass than is the hinny, which is the offspring of the female-ass and stallion. Much stress has been laid by some authors on the supposed fact, that it is only with mongrels that the offspring are not intermediate in character, but closely resemble one of their parents; but this does sometimes occur with hybrids, yet I grant much less frequently than with mongrels. Looking to the cases which I have collected of cross-bred animals closely resembling one parent, the resemblances seem chiefly confined to characters almost monstrous in their nature, and which have suddenly appeared--such as albinism, melanism, deficiency of tail or horns, or additional fingers and toes; and do not relate to characters which have been slowly acquired through selection. A tendency to sudden reversions to the perfect character of either parent would, also, be much more likely to occur with mongrels, which are descended from varieties often suddenly produced and semi-monstrous in character, than with hybrids, which are descended from species slowly and naturally produced. On the whole, I entirely agree with Dr. Prosper Lucas, who, after arranging an enormous body of facts with respect to animals, comes to the conclusion that the laws of resemblance of the child to its parents are the same, whether the two parents differ little or much from each other, namely, in the union of individuals of the same variety, or of different varieties, or of distinct species. Independently of the question of fertility and sterility, in all other respects there seems to be a general and close similarity in the offspring of crossed species, and of crossed varieties. If we look at species as having been specially created, and at varieties as having been produced by secondary laws, this similarity would be an astonishing fact. But it harmonises perfectly with the view that there is no essential distinction between species and varieties. SUMMARY OF CHAPTER. First crosses between forms, sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile. The sterility is of all degrees, and is often so slight that the most careful experimentalists have arrived at diametrically opposite conclusions in ranking forms by this test. The sterility is innately variable in individuals of the same species, and is eminently susceptible to action of favourable and unfavourable conditions. The degree of sterility does not strictly follow systematic affinity, but is governed by several curious and complex laws. It is generally different, and sometimes widely different in reciprocal crosses between the same two species. It is not always equal in degree in a first cross and in the hybrids produced from this cross. In the same manner as in grafting trees, the capacity in one species or variety to take on another, is incidental on differences, generally of an unknown nature, in their vegetative systems, so in crossing, the greater or less facility of one species to unite with another is incidental on unknown differences in their reproductive systems. There is no more reason to think that species have been specially endowed with various degrees of sterility to prevent their crossing and blending in nature, than to think that trees have been specially endowed with various and somewhat analogous degrees of difficulty in being grafted together in order to prevent their inarching in our forests. The sterility of first crosses and of their hybrid progeny has not been acquired through natural selection. In the case of first crosses it seems to depend on several circumstances; in some instances in chief part on the early death of the embryo. In the case of hybrids, it apparently depends on their whole organisation having been disturbed by being compounded from two distinct forms; the sterility being closely allied to that which so frequently affects pure species, when exposed to new and unnatural conditions of life. He who will explain these latter cases will be able to explain the sterility of hybrids. This view is strongly supported by a parallelism of another kind: namely, that, firstly, slight changes in the conditions of life add to the vigour and fertility of all organic beings; and secondly, that the crossing of forms, which have been exposed to slightly different conditions of life, or which have varied, favours the size, vigour and fertility of their offspring. The facts given on the sterility of the illegitimate unions of dimorphic and trimorphic plants and of their illegitimate progeny, perhaps render it probable that some unknown bond in all cases connects the degree of fertility of first unions with that of their offspring. The consideration of these facts on dimorphism, as well as of the results of reciprocal crosses, clearly leads to the conclusion that the primary cause of the sterility of crossed species is confined to differences in their sexual elements. But why, in the case of distinct species, the sexual elements should so generally have become more or less modified, leading to their mutual infertility, we do not know; but it seems to stand in some close relation to species having been exposed for long periods of time to nearly uniform conditions of life. It is not surprising that the difficulty in crossing any two species, and the sterility of their hybrid offspring, should in most cases correspond, even if due to distinct causes: for both depend on the amount of difference between the species which are crossed. Nor is it surprising that the facility of effecting a first cross, and the fertility of the hybrids thus produced, and the capacity of being grafted together--though this latter capacity evidently depends on widely different circumstances--should all run, to a certain extent, parallel with the systematic affinity of the forms subjected to experiment; for systematic affinity includes resemblances of all kinds. First crosses between forms known to be varieties, or sufficiently alike to be considered as varieties, and their mongrel offspring, are very generally, but not, as is so often stated, invariably fertile. Nor is this almost universal and perfect fertility surprising, when it is remembered how liable we are to argue in a circle with respect to varieties in a state of nature; and when we remember that the greater number of varieties have been produced under domestication by the selection of mere external differences, and that they have not been long exposed to uniform conditions of life. It should also be especially kept in mind, that long-continued domestication tends to eliminate sterility, and is therefore little likely to induce this same quality. Independently of the question of fertility, in all other respects there is the closest general resemblance between hybrids and mongrels, in their variability, in their power of absorbing each other by repeated crosses, and in their inheritance of characters from both parent-forms. Finally, then, although we are as ignorant of the precise cause of the sterility of first crosses and of hybrids as we are why animals and plants removed from their natural conditions become sterile, yet the facts given in this chapter do not seem to me opposed to the belief that species aboriginally existed as varieties. CHAPTER X. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD. On the absence of intermediate varieties at the present day--On the nature of extinct intermediate varieties; on their number--On the lapse of time, as inferred from the rate of denudation and of deposition number--On the lapse of time as estimated by years--On the poorness of our palaeontological collections--On the intermittence of geological formations--On the denudation of granitic areas--On the absence of intermediate varieties in any one formation--On the sudden appearance of groups of species--On their sudden appearance in the lowest known fossiliferous strata--Antiquity of the habitable earth. In the sixth chapter I enumerated the chief objections which might be justly urged against the views maintained in this volume. Most of them have now been discussed. One, namely, the distinctness of specific forms and their not being blended together by innumerable transitional links, is a very obvious difficulty. I assigned reasons why such links do not commonly occur at the present day under the circumstances apparently most favourable for their presence, namely, on an extensive and continuous area with graduated physical conditions. I endeavoured to show, that the life of each species depends in a more important manner on the presence of other already defined organic forms, than on climate, and, therefore, that the really governing conditions of life do not graduate away quite insensibly like heat or moisture. I endeavoured, also, to show that intermediate varieties, from existing in lesser numbers than the forms which they connect, will generally be beaten out and exterminated during the course of further modification and improvement. The main cause, however, of innumerable intermediate links not now occurring everywhere throughout nature depends, on the very process of natural selection, through which new varieties continually take the places of and supplant their parent-forms. But just in proportion as this process of extermination has acted on an enormous scale, so must the number of intermediate varieties, which have formerly existed, be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and serious objection which can be urged against my theory. The explanation lies, as I believe, in the extreme imperfection of the geological record. In the first place, it should always be borne in mind what sort of intermediate forms must, on the theory, have formerly existed. I have found it difficult, when looking at any two species, to avoid picturing to myself forms DIRECTLY intermediate between them. But this is a wholly false view; we should always look for forms intermediate between each species and a common but unknown progenitor; and the progenitor will generally have differed in some respects from all its modified descendants. To give a simple illustration: the fantail and pouter pigeons are both descended from the rock-pigeon; if we possessed all the intermediate varieties which have ever existed, we should have an extremely close series between both and the rock-pigeon; but we should have no varieties directly intermediate between the fantail and pouter; none, for instance, combining a tail somewhat expanded with a crop somewhat enlarged, the characteristic features of these two breeds. These two breeds, moreover, have become so much modified, that, if we had no historical or indirect evidence regarding their origin, it would not have been possible to have determined from a mere comparison of their structure with that of the rock-pigeon, C. livia, whether they had descended from this species or from some other allied species, such as C. oenas. So with natural species, if we look to forms very distinct, for instance to the horse and tapir, we have no reason to suppose that links directly intermediate between them ever existed, but between each and an unknown common parent. The common parent will have had in its whole organisation much general resemblance to the tapir and to the horse; but in some points of structure may have differed considerably from both, even perhaps more than they differ from each other. Hence, in all such cases, we should be unable to recognise the parent-form of any two or more species, even if we closely compared the structure of the parent with that of its modified descendants, unless at the same time we had a nearly perfect chain of the intermediate links. It is just possible, by the theory, that one of two living forms might have descended from the other; for instance, a horse from a tapir; and in this case DIRECT intermediate links will have existed between them. But such a case would imply that one form had remained for a very long period unaltered, whilst its descendants had undergone a vast amount of change; and the principle of competition between organism and organism, between child and parent, will render this a very rare event; for in all cases the new and improved forms of life tend to supplant the old and unimproved forms. By the theory of natural selection all living species have been connected with the parent-species of each genus, by differences not greater than we see between the natural and domestic varieties of the same species at the present day; and these parent-species, now generally extinct, have in their turn been similarly connected with more ancient forms; and so on backwards, always converging to the common ancestor of each great class. So that the number of intermediate and transitional links, between all living and extinct species, must have been inconceivably great. But assuredly, if this theory be true, such have lived upon the earth. ON THE LAPSE OF TIME, AS INFERRED FROM THE RATE OF DEPOSITION AND EXTENT OF DENUDATION. Independently of our not finding fossil remains of such infinitely numerous connecting links, it may be objected that time cannot have sufficed for so great an amount of organic change, all changes having been effected slowly. It is hardly possible for me to recall to the reader who is not a practical geologist, the facts leading the mind feebly to comprehend the lapse of time. He who can read Sir Charles Lyell's grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, and yet does not admit how vast have been the past periods of time, may at once close this volume. Not that it suffices to study the Principles of Geology, or to read special treatises by different observers on separate formations, and to mark how each author attempts to give an inadequate idea of the duration of each formation, or even of each stratum. We can best gain some idea of past time by knowing the agencies at work; and learning how deeply the surface of the land has been denuded, and how much sediment has been deposited. As Lyell has well remarked, the extent and thickness of our sedimentary formations are the result and the measure of the denudation which the earth's crust has elsewhere undergone. Therefore a man should examine for himself the great piles of superimposed strata, and watch the rivulets bringing down mud, and the waves wearing away the sea-cliffs, in order to comprehend something about the duration of past time, the monuments of which we see all around us. It is good to wander along the coast, when formed of moderately hard rocks, and mark the process of degradation. The tides in most cases reach the cliffs only for a short time twice a day, and the waves eat into them only when they are charged with sand or pebbles; for there is good evidence that pure water effects nothing in wearing away rock. At last the base of the cliff is undermined, huge fragments fall down, and these remaining fixed, have to be worn away atom by atom, until after being reduced in size they can be rolled about by the waves, and then they are more quickly ground into pebbles, sand, or mud. But how often do we see along the bases of retreating cliffs rounded boulders, all thickly clothed by marine productions, showing how little they are abraded and how seldom they are rolled about! Moreover, if we follow for a few miles any line of rocky cliff, which is undergoing degradation, we find that it is only here and there, along a short length or round a promontory, that the cliffs are at the present time suffering. The appearance of the surface and the vegetation show that elsewhere years have elapsed since the waters washed their base. We have, however, recently learned from the observations of Ramsay, in the van of many excellent observers--of Jukes, Geikie, Croll and others, that subaerial degradation is a much more important agency than coast-action, or the power of the waves. The whole surface of the land is exposed to the chemical action of the air and of the rainwater, with its dissolved carbonic acid, and in colder countries to frost; the disintegrated matter is carried down even gentle slopes during heavy rain, and to a greater extent than might be supposed, especially in arid districts, by the wind; it is then transported by the streams and rivers, which, when rapid deepen their channels, and triturate the fragments. On a rainy day, even in a gently undulating country, we see the effects of subaerial degradation in the muddy rills which flow down every slope. Messrs. Ramsay and Whitaker have shown, and the observation is a most striking one, that the great lines of escarpment in the Wealden district and those ranging across England, which formerly were looked at as ancient sea-coasts, cannot have been thus formed, for each line is composed of one and the same formation, while our sea-cliffs are everywhere formed by the intersection of various formations. This being the case, we are compelled to admit that the escarpments owe their origin in chief part to the rocks of which they are composed, having resisted subaerial denudation better than the surrounding surface; this surface consequently has been gradually lowered, with the lines of harder rock left projecting. Nothing impresses the mind with the vast duration of time, according to our ideas of time, more forcibly than the conviction thus gained that subaerial agencies, which apparently have so little power, and which seem to work so slowly, have produced great results. When thus impressed with the slow rate at which the land is worn away through subaerial and littoral action, it is good, in order to appreciate the past duration of time, to consider, on the one hand, the masses of rock which have been removed over many extensive areas, and on the other hand the thickness of our sedimentary formations. I remember having been much struck when viewing volcanic islands, which have been worn by the waves and pared all round into perpendicular cliffs of one or two thousand feet in height; for the gentle slope of the lava-streams, due to their formerly liquid state, showed at a glance how far the hard, rocky beds had once extended into the open ocean. The same story is told still more plainly by faults--those great cracks along which the strata have been upheaved on one side, or thrown down on the other, to the height or depth of thousands of feet; for since the crust cracked, and it makes no great difference whether the upheaval was sudden, or, as most geologists now believe, was slow and effected by many starts, the surface of the land has been so completely planed down that no trace of these vast dislocations is externally visible. The Craven fault, for instance, extends for upward of thirty miles, and along this line the vertical displacement of the strata varies from 600 to 3,000 feet. Professor Ramsay has published an account of a downthrow in Anglesea of 2,300 feet; and he informs me that he fully believes that there is one in Merionethshire of 12,000 feet; yet in these cases there is nothing on the surface of the land to show such prodigious movements; the pile of rocks on either side of the crack having been smoothly swept away. On the other hand, in all parts of the world the piles of sedimentary strata are of wonderful thickness. In the Cordillera, I estimated one mass of conglomerate at ten thousand feet; and although conglomerates have probably been accumulated at a quicker rate than finer sediments, yet from being formed of worn and rounded pebbles, each of which bears the stamp of time, they are good to show how slowly the mass must have been heaped together. Professor Ramsay has given me the maximum thickness, from actual measurement in most cases, of the successive formations in DIFFERENT parts of Great Britain; and this is the result:-- Feet Palaeozoic strata (not including igneous beds)..57,154 Secondary strata................................13,190 Tertiary strata..................................2,240 --making altogether 72,584 feet; that is, very nearly thirteen and three-quarters British miles. Some of these formations, which are represented in England by thin beds, are thousands of feet in thickness on the Continent. Moreover, between each successive formation we have, in the opinion of most geologists, blank periods of enormous length. So that the lofty pile of sedimentary rocks in Britain gives but an inadequate idea of the time which has elapsed during their accumulation. The consideration of these various facts impresses the mind almost in the same manner as does the vain endeavour to grapple with the idea of eternity. Nevertheless this impression is partly false. Mr. Croll, in an interesting paper, remarks that we do not err "in forming too great a conception of the length of geological periods," but in estimating them by years. When geologists look at large and complicated phenomena, and then at the figures representing several million years, the two produce a totally different effect on the mind, and the figures are at once pronounced too small. In regard to subaerial denudation, Mr. Croll shows, by calculating the known amount of sediment annually brought down by certain rivers, relatively to their areas of drainage, that 1,000 feet of solid rock, as it became gradually disintegrated, would thus be removed from the mean level of the whole area in the course of six million years. This seems an astonishing result, and some considerations lead to the suspicion that it may be too large, but if halved or quartered it is still very surprising. Few of us, however, know what a million really means: Mr. Croll gives the following illustration: Take a narrow strip of paper, eighty-three feet four inches in length, and stretch it along the wall of a large hall; then mark off at one end the tenth of an inch. This tenth of an inch will represent one hundred years, and the entire strip a million years. But let it be borne in mind, in relation to the subject of this work, what a hundred years implies, represented as it is by a measure utterly insignificant in a hall of the above dimensions. Several eminent breeders, during a single lifetime, have so largely modified some of the higher animals, which propagate their kind much more slowly than most of the lower animals, that they have formed what well deserves to be called a new sub-breed. Few men have attended with due care to any one strain for more than half a century, so that a hundred years represents the work of two breeders in succession. It is not to be supposed that species in a state of nature ever change so quickly as domestic animals under the guidance of methodical selection. The comparison would be in every way fairer with the effects which follow from unconscious selection, that is, the preservation of the most useful or beautiful animals, with no intention of modifying the breed; but by this process of unconscious selection, various breeds have been sensibly changed in the course of two or three centuries. Species, however, probably change much more slowly, and within the same country only a few change at the same time. This slowness follows from all the inhabitants of the same country being already so well adapted to each other, that new places in the polity of nature do not occur until after long intervals, due to the occurrence of physical changes of some kind, or through the immigration of new forms. Moreover, variations or individual differences of the right nature, by which some of the inhabitants might be better fitted to their new places under the altered circumstance, would not always occur at once. Unfortunately we have no means of determining, according to the standard of years, how long a period it takes to modify a species; but to the subject of time we must return. ON THE POORNESS OF PALAEONTOLOGICAL COLLECTIONS. Now let us turn to our richest museums, and what a paltry display we behold! That our collections are imperfect is admitted by every one. The remark of that admirable palaeontologist, Edward Forbes, should never be forgotten, namely, that very many fossil species are known and named from single and often broken specimens, or from a few specimens collected on some one spot. Only a small portion of the surface of the earth has been geologically explored, and no part with sufficient care, as the important discoveries made every year in Europe prove. No organism wholly soft can be preserved. Shells and bones decay and disappear when left on the bottom of the sea, where sediment is not accumulating. We probably take a quite erroneous view, when we assume that sediment is being deposited over nearly the whole bed of the sea, at a rate sufficiently quick to embed and preserve fossil remains. Throughout an enormously large proportion of the ocean, the bright blue tint of the water bespeaks its purity. The many cases on record of a formation conformably covered, after an immense interval of time, by another and later formation, without the underlying bed having suffered in the interval any wear and tear, seem explicable only on the view of the bottom of the sea not rarely lying for ages in an unaltered condition. The remains which do become embedded, if in sand or gravel, will, when the beds are upraised, generally be dissolved by the percolation of rain water charged with carbonic acid. Some of the many kinds of animals which live on the beach between high and low water mark seem to be rarely preserved. For instance, the several species of the Chthamalinae (a sub-family of sessile cirripedes) coat the rocks all over the world in infinite numbers: they are all strictly littoral, with the exception of a single Mediterranean species, which inhabits deep water and this has been found fossil in Sicily, whereas not one other species has hitherto been found in any tertiary formation: yet it is known that the genus Chthamalus existed during the Chalk period. Lastly, many great deposits, requiring a vast length of time for their accumulation, are entirely destitute of organic remains, without our being able to assign any reason: one of the most striking instances is that of the Flysch formation, which consists of shale and sandstone, several thousand, occasionally even six thousand feet in thickness, and extending for at least 300 miles from Vienna to Switzerland; and although this great mass has been most carefully searched, no fossils, except a few vegetable remains, have been found. With respect to the terrestrial productions which lived during the Secondary and Palaeozoic periods, it is superfluous to state that our evidence is fragmentary in an extreme degree. For instance, until recently not a land-shell was known belonging to either of these vast periods, with the exception of one species discovered by Sir C. Lyell and Dr. Dawson in the carboniferous strata of North America; but now land-shells have been found in the lias. In regard to mammiferous remains, a glance at the historical table published in Lyell's Manual, will bring home the truth, how accidental and rare is their preservation, far better than pages of detail. Nor is their rarity surprising, when we remember how large a proportion of the bones of tertiary mammals have been discovered either in caves or in lacustrine deposits; and that not a cave or true lacustrine bed is known belonging to the age of our secondary or palaeozoic formations. But the imperfection in the geological record largely results from another and more important cause than any of the foregoing; namely, from the several formations being separated from each other by wide intervals of time. This doctrine has been emphatically admitted by many geologists and palaeontologists, who, like E. Forbes, entirely disbelieve in the change of species. When we see the formations tabulated in written works, or when we follow them in nature, it is difficult to avoid believing that they are closely consecutive. But we know, for instance, from Sir R. Murchison's great work on Russia, what wide gaps there are in that country between the superimposed formations; so it is in North America, and in many other parts of the world. The most skilful geologist, if his attention had been confined exclusively to these large territories, would never have suspected that during the periods which were blank and barren in his own country, great piles of sediment, charged with new and peculiar forms of life, had elsewhere been accumulated. And if, in every separate territory, hardly any idea can be formed of the length of time which has elapsed between the consecutive formations, we may infer that this could nowhere be ascertained. The frequent and great changes in the mineralogical composition of consecutive formations, generally implying great changes in the geography of the surrounding lands, whence the sediment was derived, accord with the belief of vast intervals of time having elapsed between each formation. We can, I think, see why the geological formations of each region are almost invariably intermittent; that is, have not followed each other in close sequence. Scarcely any fact struck me more when examining many hundred miles of the South American coasts, which have been upraised several hundred feet within the recent period, than the absence of any recent deposits sufficiently extensive to last for even a short geological period. Along the whole west coast, which is inhabited by a peculiar marine fauna, tertiary beds are so poorly developed that no record of several successive and peculiar marine faunas will probably be preserved to a distant age. A little reflection will explain why, along the rising coast of the western side of South America, no extensive formations with recent or tertiary remains can anywhere be found, though the supply of sediment must for ages have been great, from the enormous degradation of the coast rocks and from the muddy streams entering the sea. The explanation, no doubt, is that the littoral and sub-littoral deposits are continually worn away, as soon as they are brought up by the slow and gradual rising of the land within the grinding action of the coast-waves. We may, I think, conclude that sediment must be accumulated in extremely thick, solid, or extensive masses, in order to withstand the incessant action of the waves, when first upraised and during subsequent oscillations of level, as well as the subsequent subaerial degradation. Such thick and extensive accumulations of sediment may be formed in two ways; either in profound depths of the sea, in which case the bottom will not be inhabited by so many and such varied forms of life as the more shallow seas; and the mass when upraised will give an imperfect record of the organisms which existed in the neighbourhood during the period of its accumulation. Or sediment may be deposited to any thickness and extent over a shallow bottom, if it continue slowly to subside. In this latter case, as long as the rate of subsidence and supply of sediment nearly balance each other, the sea will remain shallow and favourable for many and varied forms, and thus a rich fossiliferous formation, thick enough, when upraised, to resist a large amount of denudation, may be formed. I am convinced that nearly all our ancient formations, which are throughout the greater part of their thickness RICH IN FOSSILS, have thus been formed during subsidence. Since publishing my views on this subject in 1845, I have watched the progress of geology, and have been surprised to note how author after author, in treating of this or that great formation, has come to the conclusion that it was accumulated during subsidence. I may add, that the only ancient tertiary formation on the west coast of South America, which has been bulky enough to resist such degradation as it has as yet suffered, but which will hardly last to a distant geological age, was deposited during a downward oscillation of level, and thus gained considerable thickness. All geological facts tell us plainly that each area has undergone numerous slow oscillations of level, and apparently these oscillations have affected wide spaces. Consequently, formations rich in fossils and sufficiently thick and extensive to resist subsequent degradation, will have been formed over wide spaces during periods of subsidence, but only where the supply of sediment was sufficient to keep the sea shallow and to embed and preserve the remains before they had time to decay. On the other hand, as long as the bed of the sea remained stationary, THICK deposits cannot have been accumulated in the shallow parts, which are the most favourable to life. Still less can this have happened during the alternate periods of elevation; or, to speak more accurately, the beds which were then accumulated will generally have been destroyed by being upraised and brought within the limits of the coast-action. These remarks apply chiefly to littoral and sublittoral deposits. In the case of an extensive and shallow sea, such as that within a large part of the Malay Archipelago, where the depth varies from thirty or forty to sixty fathoms, a widely extended formation might be formed during a period of elevation, and yet not suffer excessively from denudation during its slow upheaval; but the thickness of the formation could not be great, for owing to the elevatory movement it would be less than the depth in which it was formed; nor would the deposit be much consolidated, nor be capped by overlying formations, so that it would run a good chance of being worn away by atmospheric degradation and by the action of the sea during subsequent oscillations of level. It has, however, been suggested by Mr. Hopkins, that if one part of the area, after rising and before being denuded, subsided, the deposit formed during the rising movement, though not thick, might afterwards become protected by fresh accumulations, and thus be preserved for a long period. Mr. Hopkins also expresses his belief that sedimentary beds of considerable horizontal extent have rarely been completely destroyed. But all geologists, excepting the few who believe that our present metamorphic schists and plutonic rocks once formed the primordial nucleus of the globe, will admit that these latter rocks have been stripped of their covering to an enormous extent. For it is scarcely possible that such rocks could have been solidified and crystallised while uncovered; but if the metamorphic action occurred at profound depths of the ocean, the former protecting mantle of rock may not have been very thick. Admitting then that gneiss, mica-schist, granite, diorite, etc., were once necessarily covered up, how can we account for the naked and extensive areas of such rocks in many parts of the world, except on the belief that they have subsequently been completely denuded of all overlying strata? That such extensive areas do exist cannot be doubted: the granitic region of Parime is described by Humboldt as being at least nineteen times as large as Switzerland. South of the Amazon, Boue colours an area composed of rocks of this nature as equal to that of Spain, France, Italy, part of Germany, and the British Islands, all conjoined. This region has not been carefully explored, but from the concurrent testimony of travellers, the granitic area is very large: thus Von Eschwege gives a detailed section of these rocks, stretching from Rio de Janeiro for 260 geographical miles inland in a straight line; and I travelled for 150 miles in another direction, and saw nothing but granitic rocks. Numerous specimens, collected along the whole coast, from near Rio de Janeiro to the mouth of the Plata, a distance of 1,100 geographical miles, were examined by me, and they all belonged to this class. Inland, along the whole northern bank of the Plata, I saw, besides modern tertiary beds, only one small patch of slightly metamorphosed rock, which alone could have formed a part of the original capping of the granitic series. Turning to a well-known region, namely, to the United States and Canada, as shown in Professor H.D. Rogers' beautiful map, I have estimated the areas by cutting out and weighing the paper, and I find that the metamorphic (excluding the "semi-metamorphic") and granite rocks exceed, in the proportion of 19 to 12.5, the whole of the newer Palaeozoic formations. In many regions the metamorphic and granite rocks would be found much more widely extended than they appear to be, if all the sedimentary beds were removed which rest unconformably on them, and which could not have formed part of the original mantle under which they were crystallised. Hence, it is probable that in some parts of the world whole formations have been completely denuded, with not a wreck left behind. One remark is here worth a passing notice. During periods of elevation the area of the land and of the adjoining shoal parts of the sea will be increased and new stations will often be formed--all circumstances favourable, as previously explained, for the formation of new varieties and species; but during such periods there will generally be a blank in the geological record. On the other hand, during subsidence, the inhabited area and number of inhabitants will decrease (excepting on the shores of a continent when first broken up into an archipelago), and consequently during subsidence, though there will be much extinction, few new varieties or species will be formed; and it is during these very periods of subsidence that the deposits which are richest in fossils have been accumulated. ON THE ABSENCE OF NUMEROUS INTERMEDIATE VARIETIES IN ANY SINGLE FORMATION. From these several considerations it cannot be doubted that the geological record, viewed as a whole, is extremely imperfect; but if we confine our attention to any one formation, it becomes much more difficult to understand why we do not therein find closely graduated varieties between the allied species which lived at its commencement and at its close. Several cases are on record of the same species presenting varieties in the upper and lower parts of the same formation. Thus Trautschold gives a number of instances with Ammonites, and Hilgendorf has described a most curious case of ten graduated forms of Planorbis multiformis in the successive beds of a fresh-water formation in Switzerland. Although each formation has indisputably required a vast number of years for its deposition, several reasons can be given why each should not commonly include a graduated series of links between the species which lived at its commencement and close, but I cannot assign due proportional weight to the following considerations. Although each formation may mark a very long lapse of years, each probably is short compared with the period requisite to change one species into another. I am aware that two palaeontologists, whose opinions are worthy of much deference, namely Bronn and Woodward, have concluded that the average duration of each formation is twice or thrice as long as the average duration of specific forms. But insuperable difficulties, as it seems to me, prevent us from coming to any just conclusion on this head. When we see a species first appearing in the middle of any formation, it would be rash in the extreme to infer that it had not elsewhere previously existed. So again, when we find a species disappearing before the last layers have been deposited, it would be equally rash to suppose that it then became extinct. We forget how small the area of Europe is compared with the rest of the world; nor have the several stages of the same formation throughout Europe been correlated with perfect accuracy. We may safely infer that with marine animals of all kinds there has been a large amount of migration due to climatal and other changes; and when we see a species first appearing in any formation, the probability is that it only then first immigrated into that area. It is well known, for instance, that several species appear somewhat earlier in the palaeozoic beds of North America than in those of Europe; time having apparently been required for their migration from the American to the European seas. In examining the latest deposits, in various quarters of the world, it has everywhere been noted, that some few still existing species are common in the deposit, but have become extinct in the immediately surrounding sea; or, conversely, that some are now abundant in the neighbouring sea, but are rare or absent in this particular deposit. It is an excellent lesson to reflect on the ascertained amount of migration of the inhabitants of Europe during the glacial epoch, which forms only a part of one whole geological period; and likewise to reflect on the changes of level, on the extreme change of climate, and on the great lapse of time, all included within this same glacial period. Yet it may be doubted whether, in any quarter of the world, sedimentary deposits, INCLUDING FOSSIL REMAINS, have gone on accumulating within the same area during the whole of this period. It is not, for instance, probable that sediment was deposited during the whole of the glacial period near the mouth of the Mississippi, within that limit of depth at which marine animals can best flourish: for we know that great geographical changes occurred in other parts of America during this space of time. When such beds as were deposited in shallow water near the mouth of the Mississippi during some part of the glacial period shall have been upraised, organic remains will probably first appear and disappear at different levels, owing to the migrations of species and to geographical changes. And in the distant future, a geologist, examining these beds, would be tempted to conclude that the average duration of life of the embedded fossils had been less than that of the glacial period, instead of having been really far greater, that is, extending from before the glacial epoch to the present day. In order to get a perfect gradation between two forms in the upper and lower parts of the same formation, the deposit must have gone on continuously accumulating during a long period, sufficient for the slow process of modification; hence, the deposit must be a very thick one; and the species undergoing change must have lived in the same district throughout the whole time. But we have seen that a thick formation, fossiliferous throughout its entire thickness, can accumulate only during a period of subsidence; and to keep the depth approximately the same, which is necessary that the same marine species may live on the same space, the supply of sediment must nearly counterbalance the amount of subsidence. But this same movement of subsidence will tend to submerge the area whence the sediment is derived, and thus diminish the supply, whilst the downward movement continues. In fact, this nearly exact balancing between the supply of sediment and the amount of subsidence is probably a rare contingency; for it has been observed by more than one palaeontologist that very thick deposits are usually barren of organic remains, except near their upper or lower limits. It would seem that each separate formation, like the whole pile of formations in any country, has generally been intermittent in its accumulation. When we see, as is so often the case, a formation composed of beds of widely different mineralogical composition, we may reasonably suspect that the process of deposition has been more or less interrupted. Nor will the closest inspection of a formation give us any idea of the length of time which its deposition may have consumed. Many instances could be given of beds, only a few feet in thickness, representing formations which are elsewhere thousands of feet in thickness, and which must have required an enormous period for their accumulation; yet no one ignorant of this fact would have even suspected the vast lapse of time represented by the thinner formation. Many cases could be given of the lower beds of a formation having been upraised, denuded, submerged, and then re-covered by the upper beds of the same formation--facts, showing what wide, yet easily overlooked, intervals have occurred in its accumulation. In other cases we have the plainest evidence in great fossilised trees, still standing upright as they grew, of many long intervals of time and changes of level during the process of deposition, which would not have been suspected, had not the trees been preserved: thus Sir C. Lyell and Dr. Dawson found carboniferous beds 1,400 feet thick in Nova Scotia, with ancient root-bearing strata, one above the other, at no less than sixty-eight different levels. Hence, when the same species occurs at the bottom, middle, and top of a formation, the probability is that it has not lived on the same spot during the whole period of deposition, but has disappeared and reappeared, perhaps many times, during the same geological period. Consequently if it were to undergo a considerable amount of modification during the deposition of any one geological formation, a section would not include all the fine intermediate gradations which must on our theory have existed, but abrupt, though perhaps slight, changes of form. It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; they grant some little variability to each species, but when they meet with a somewhat greater amount of difference between any two forms, they rank both as species, unless they are enabled to connect them together by the closest intermediate gradations; and this, from the reasons just assigned, we can seldom hope to effect in any one geological section. Supposing B and C to be two species, and a third, A, to be found in an older and underlying bed; even if A were strictly intermediate between B and C, it would simply be ranked as a third and distinct species, unless at the same time it could be closely connected by intermediate varieties with either one or both forms. Nor should it be forgotten, as before explained, that A might be the actual progenitor of B and C, and yet would not necessarily be strictly intermediate between them in all respects. So that we might obtain the parent-species and its several modified descendants from the lower and upper beds of the same formation, and unless we obtained numerous transitional gradations, we should not recognise their blood-relationship, and should consequently rank them as distinct species. It is notorious on what excessively slight differences many palaeontologists have founded their species; and they do this the more readily if the specimens come from different sub-stages of the same formation. Some experienced conchologists are now sinking many of the very fine species of D'Orbigny and others into the rank of varieties; and on this view we do find the kind of evidence of change which on the theory we ought to find. Look again at the later tertiary deposits, which include many shells believed by the majority of naturalists to be identical with existing species; but some excellent naturalists, as Agassiz and Pictet, maintain that all these tertiary species are specifically distinct, though the distinction is admitted to be very slight; so that here, unless we believe that these eminent naturalists have been misled by their imaginations, and that these late tertiary species really present no difference whatever from their living representatives, or unless we admit, in opposition to the judgment of most naturalists, that these tertiary species are all truly distinct from the recent, we have evidence of the frequent occurrence of slight modifications of the kind required. If we look to rather wider intervals of time, namely, to distinct but consecutive stages of the same great formation, we find that the embedded fossils, though universally ranked as specifically different, yet are far more closely related to each other than are the species found in more widely separated formations; so that here again we have undoubted evidence of change in the direction required by the theory; but to this latter subject I shall return in the following chapter. With animals and plants that propagate rapidly and do not wander much, there is reason to suspect, as we have formerly seen, that their varieties are generally at first local; and that such local varieties do not spread widely and supplant their parent-form until they have been modified and perfected in some considerable degree. According to this view, the chance of discovering in a formation in any one country all the early stages of transition between any two forms, is small, for the successive changes are supposed to have been local or confined to some one spot. Most marine animals have a wide range; and we have seen that with plants it is those which have the widest range, that oftenest present varieties, so that, with shells and other marine animals, it is probable that those which had the widest range, far exceeding the limits of the known geological formations in Europe, have oftenest given rise, first to local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any one geological formation. It is a more important consideration, leading to the same result, as lately insisted on by Dr. Falconer, namely, that the period during which each species underwent modification, though long as measured by years, was probably short in comparison with that during which it remained without undergoing any change. It should not be forgotten, that at the present day, with perfect specimens for examination, two forms can seldom be connected by intermediate varieties, and thus proved to be the same species, until many specimens are collected from many places; and with fossil species this can rarely be done. We shall, perhaps, best perceive the improbability of our being enabled to connect species by numerous, fine, intermediate, fossil links, by asking ourselves whether, for instance, geologists at some future period will be able to prove that our different breeds of cattle, sheep, horses, and dogs are descended from a single stock or from several aboriginal stocks; or, again, whether certain sea-shells inhabiting the shores of North America, which are ranked by some conchologists as distinct species from their European representatives, and by other conchologists as only varieties, are really varieties, or are, as it is called, specifically distinct. This could be effected by the future geologist only by his discovering in a fossil state numerous intermediate gradations; and such success is improbable in the highest degree. It has been asserted over and over again, by writers who believe in the immutability of species, that geology yields no linking forms. This assertion, as we shall see in the next chapter, is certainly erroneous. As Sir J. Lubbock has remarked, "Every species is a link between other allied forms." If we take a genus having a score of species, recent and extinct, and destroy four-fifths of them, no one doubts that the remainder will stand much more distinct from each other. If the extreme forms in the genus happen to have been thus destroyed, the genus itself will stand more distinct from other allied genera. What geological research has not revealed, is the former existence of infinitely numerous gradations, as fine as existing varieties, connecting together nearly all existing and extinct species. But this ought not to be expected; yet this has been repeatedly advanced as a most serious objection against my views. It may be worth while to sum up the foregoing remarks on the causes of the imperfection of the geological record under an imaginary illustration. The Malay Archipelago is about the size of Europe from the North Cape to the Mediterranean, and from Britain to Russia; and therefore equals all the geological formations which have been examined with any accuracy, excepting those of the United States of America. I fully agree with Mr. Godwin-Austen, that the present condition of the Malay Archipelago, with its numerous large islands separated by wide and shallow seas, probably represents the former state of Europe, while most of our formations were accumulating. The Malay Archipelago is one of the richest regions in organic beings; yet if all the species were to be collected which have ever lived there, how imperfectly would they represent the natural history of the world! But we have every reason to believe that the terrestrial productions of the archipelago would be preserved in an extremely imperfect manner in the formations which we suppose to be there accumulating. Not many of the strictly littoral animals, or of those which lived on naked submarine rocks, would be embedded; and those embedded in gravel or sand would not endure to a distant epoch. Wherever sediment did not accumulate on the bed of the sea, or where it did not accumulate at a sufficient rate to protect organic bodies from decay, no remains could be preserved. Formations rich in fossils of many kinds, and of thickness sufficient to last to an age as distant in futurity as the secondary formations lie in the past, would generally be formed in the archipelago only during periods of subsidence. These periods of subsidence would be separated from each other by immense intervals of time, during which the area would be either stationary or rising; whilst rising, the fossiliferous formations on the steeper shores would be destroyed, almost as soon as accumulated, by the incessant coast-action, as we now see on the shores of South America. Even throughout the extensive and shallow seas within the archipelago, sedimentary beds could hardly be accumulated of great thickness during the periods of elevation, or become capped and protected by subsequent deposits, so as to have a good chance of enduring to a very distant future. During the periods of subsidence, there would probably be much extinction of life; during the periods of elevation, there would be much variation, but the geological record would then be less perfect. It may be doubted whether the duration of any one great period of subsidence over the whole or part of the archipelago, together with a contemporaneous accumulation of sediment, would EXCEED the average duration of the same specific forms; and these contingencies are indispensable for the preservation of all the transitional gradations between any two or more species. If such gradations were not all fully preserved, transitional varieties would merely appear as so many new, though closely allied species. It is also probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatical changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would migrate, and no closely consecutive record of their modifications could be preserved in any one formation. Very many of the marine inhabitants of the archipelago now range thousands of miles beyond its confines; and analogy plainly leads to the belief that it would be chiefly these far-ranging species, though only some of them, which would oftenest produce new varieties; and the varieties would at first be local or confined to one place, but if possessed of any decided advantage, or when further modified and improved, they would slowly spread and supplant their parent-forms. When such varieties returned to their ancient homes, as they would differ from their former state in a nearly uniform, though perhaps extremely slight degree, and as they would be found embedded in slightly different sub-stages of the same formation, they would, according to the principles followed by many palaeontologists, be ranked as new and distinct species. If then there be some degree of truth in these remarks, we have no right to expect to find, in our geological formations, an infinite number of those fine transitional forms, which, on our theory, have connected all the past and present species of the same group into one long and branching chain of life. We ought only to look for a few links, and such assuredly we do find--some more distantly, some more closely, related to each other; and these links, let them be ever so close, if found in different stages of the same formation, would, by many palaeontologists, be ranked as distinct species. But I do not pretend that I should ever have suspected how poor was the record in the best preserved geological sections, had not the absence of innumerable transitional links between the species which lived at the commencement and close of each formation, pressed so hardly on my theory. ON THE SUDDEN APPEARANCE OF WHOLE GROUPS OF ALLIED SPECIES. The abrupt manner in which whole groups of species suddenly appear in certain formations, has been urged by several palaeontologists--for instance, by Agassiz, Pictet, and Sedgwick, as a fatal objection to the belief in the transmutation of species. If numerous species, belonging to the same genera or families, have really started into life at once, the fact would be fatal to the theory of evolution through natural selection. For the development by this means of a group of forms, all of which are descended from some one progenitor, must have been an extremely slow process; and the progenitors must have lived long before their modified descendants. But we continually overrate the perfection of the geological record, and falsely infer, because certain genera or families have not been found beneath a certain stage, that they did not exist before that stage. In all cases positive palaeontological evidence may be implicitly trusted; negative evidence is worthless, as experience has so often shown. We continually forget how large the world is, compared with the area over which our geological formations have been carefully examined; we forget that groups of species may elsewhere have long existed, and have slowly multiplied, before they invaded the ancient archipelagoes of Europe and the United States. We do not make due allowance for the enormous intervals of time which have elapsed between our consecutive formations, longer perhaps in many cases than the time required for the accumulation of each formation. These intervals will have given time for the multiplication of species from some one parent-form: and in the succeeding formation, such groups or species will appear as if suddenly created. I may here recall a remark formerly made, namely, that it might require a long succession of ages to adapt an organism to some new and peculiar line of life, for instance, to fly through the air; and consequently that the transitional forms would often long remain confined to some one region; but that, when this adaptation had once been effected, and a few species had thus acquired a great advantage over other organisms, a comparatively short time would be necessary to produce many divergent forms, which would spread rapidly and widely throughout the world. Professor Pictet, in his excellent Review of this work, in commenting on early transitional forms, and taking birds as an illustration, cannot see how the successive modifications of the anterior limbs of a supposed prototype could possibly have been of any advantage. But look at the penguins of the Southern Ocean; have not these birds their front limbs in this precise intermediate state of "neither true arms nor true wings?" Yet these birds hold their place victoriously in the battle for life; for they exist in infinite numbers and of many kinds. I do not suppose that we here see the real transitional grades through which the wings of birds have passed; but what special difficulty is there in believing that it might profit the modified descendants of the penguin, first to become enabled to flap along the surface of the sea like the logger-headed duck, and ultimately to rise from its surface and glide through the air? I will now give a few examples to illustrate the foregoing remarks, and to show how liable we are to error in supposing that whole groups of species have suddenly been produced. Even in so short an interval as that between the first and second editions of Pictet's great work on Palaeontology, published in 1844-46 and in 1853-57, the conclusions on the first appearance and disappearance of several groups of animals have been considerably modified; and a third edition would require still further changes. I may recall the well-known fact that in geological treatises, published not many years ago, mammals were always spoken of as having abruptly come in at the commencement of the tertiary series. And now one of the richest known accumulations of fossil mammals belongs to the middle of the secondary series; and true mammals have been discovered in the new red sandstone at nearly the commencement of this great series. Cuvier used to urge that no monkey occurred in any tertiary stratum; but now extinct species have been discovered in India, South America and in Europe, as far back as the miocene stage. Had it not been for the rare accident of the preservation of footsteps in the new red sandstone of the United States, who would have ventured to suppose that no less than at least thirty different bird-like animals, some of gigantic size, existed during that period? Not a fragment of bone has been discovered in these beds. Not long ago, palaeontologists maintained that the whole class of birds came suddenly into existence during the eocene period; but now we know, on the authority of Professor Owen, that a bird certainly lived during the deposition of the upper greensand; and still more recently, that strange bird, the Archeopteryx, with a long lizard-like tail, bearing a pair of feathers on each joint, and with its wings furnished with two free claws, has been discovered in the oolitic slates of Solenhofen. Hardly any recent discovery shows more forcibly than this how little we as yet know of the former inhabitants of the world. I may give another instance, which, from having passed under my own eyes has much struck me. In a memoir on Fossil Sessile Cirripedes, I stated that, from the large number of existing and extinct tertiary species; from the extraordinary abundance of the individuals of many species all over the world, from the Arctic regions to the equator, inhabiting various zones of depths, from the upper tidal limits to fifty fathoms; from the perfect manner in which specimens are preserved in the oldest tertiary beds; from the ease with which even a fragment of a valve can be recognised; from all these circumstances, I inferred that, had sessile cirripedes existed during the secondary periods, they would certainly have been preserved and discovered; and as not one species had then been discovered in beds of this age, I concluded that this great group had been suddenly developed at the commencement of the tertiary series. This was a sore trouble to me, adding, as I then thought, one more instance of the abrupt appearance of a great group of species. But my work had hardly been published, when a skilful palaeontologist, M. Bosquet, sent me a drawing of a perfect specimen of an unmistakable sessile cirripede, which he had himself extracted from the chalk of Belgium. And, as if to make the case as striking as possible, this cirripede was a Chthamalus, a very common, large, and ubiquitous genus, of which not one species has as yet been found even in any tertiary stratum. Still more recently, a Pyrgoma, a member of a distinct subfamily of sessile cirripedes, has been discovered by Mr. Woodward in the upper chalk; so that we now have abundant evidence of the existence of this group of animals during the secondary period. The case most frequently insisted on by palaeontologists of the apparently sudden appearance of a whole group of species, is that of the teleostean fishes, low down, according to Agassiz, in the Chalk period. This group includes the large majority of existing species. But certain Jurassic and Triassic forms are now commonly admitted to be teleostean; and even some palaeozoic forms have thus been classed by one high authority. If the teleosteans had really appeared suddenly in the northern hemisphere at the commencement of the chalk formation, the fact would have been highly remarkable; but it would not have formed an insuperable difficulty, unless it could likewise have been shown that at the same period the species were suddenly and simultaneously developed in other quarters of the world. It is almost superfluous to remark that hardly any fossil-fish are known from south of the equator; and by running through Pictet's Palaeontology it will be seen that very few species are known from several formations in Europe. Some few families of fish now have a confined range; the teleostean fishes might formerly have had a similarly confined range, and after having been largely developed in some one sea, have spread widely. Nor have we any right to suppose that the seas of the world have always been so freely open from south to north as they are at present. Even at this day, if the Malay Archipelago were converted into land, the tropical parts of the Indian Ocean would form a large and perfectly enclosed basin, in which any great group of marine animals might be multiplied; and here they would remain confined, until some of the species became adapted to a cooler climate, and were enabled to double the southern capes of Africa or Australia, and thus reach other and distant seas. From these considerations, from our ignorance of the geology of other countries beyond the confines of Europe and the United States, and from the revolution in our palaeontological knowledge effected by the discoveries of the last dozen years, it seems to me to be about as rash to dogmatize on the succession of organic forms throughout the world, as it would be for a naturalist to land for five minutes on a barren point in Australia, and then to discuss the number and range of its productions. ON THE SUDDEN APPEARANCE OF GROUPS OF ALLIED SPECIES IN THE LOWEST KNOWN FOSSILIFEROUS STRATA. There is another and allied difficulty, which is much more serious. I allude to the manner in which species belonging to several of the main divisions of the animal kingdom suddenly appear in the lowest known fossiliferous rocks. Most of the arguments which have convinced me that all the existing species of the same group are descended from a single progenitor, apply with equal force to the earliest known species. For instance, it cannot be doubted that all the Cambrian and Silurian trilobites are descended from some one crustacean, which must have lived long before the Cambrian age, and which probably differed greatly from any known animal. Some of the most ancient animals, as the Nautilus, Lingula, etc., do not differ much from living species; and it cannot on our theory be supposed, that these old species were the progenitors of all the species belonging to the same groups which have subsequently appeared, for they are not in any degree intermediate in character. Consequently, if the theory be true, it is indisputable that before the lowest Cambrian stratum was deposited long periods elapsed, as long as, or probably far longer than, the whole interval from the Cambrian age to the present day; and that during these vast periods the world swarmed with living creatures. Here we encounter a formidable objection; for it seems doubtful whether the earth, in a fit state for the habitation of living creatures, has lasted long enough. Sir W. Thompson concludes that the consolidation of the crust can hardly have occurred less than twenty or more than four hundred million years ago, but probably not less than ninety-eight or more than two hundred million years. These very wide limits show how doubtful the data are; and other elements may have hereafter to be introduced into the problem. Mr. Croll estimates that about sixty million years have elapsed since the Cambrian period, but this, judging from the small amount of organic change since the commencement of the Glacial epoch, appears a very short time for the many and great mutations of life, which have certainly occurred since the Cambrian formation; and the previous one hundred and forty million years can hardly be considered as sufficient for the development of the varied forms of life which already existed during the Cambrian period. It is, however, probable, as Sir William Thompson insists, that the world at a very early period was subjected to more rapid and violent changes in its physical conditions than those now occurring; and such changes would have tended to induce changes at a corresponding rate in the organisms which then existed. To the question why we do not find rich fossiliferous deposits belonging to these assumed earliest periods prior to the Cambrian system, I can give no satisfactory answer. Several eminent geologists, with Sir R. Murchison at their head, were until recently convinced that we beheld in the organic remains of the lowest Silurian stratum the first dawn of life. Other highly competent judges, as Lyell and E. Forbes, have disputed this conclusion. We should not forget that only a small portion of the world is known with accuracy. Not very long ago M. Barrande added another and lower stage, abounding with new and peculiar species, beneath the then known Silurian system; and now, still lower down in the Lower Cambrian formation, Mr Hicks has found South Wales beds rich in trilobites, and containing various molluscs and annelids. The presence of phosphatic nodules and bituminous matter, even in some of the lowest azotic rocks, probably indicates life at these periods; and the existence of the Eozoon in the Laurentian formation of Canada is generally admitted. There are three great series of strata beneath the Silurian system in Canada, in the lowest of which the Eozoon is found. Sir W. Logan states that their "united thickness may possibly far surpass that of all the succeeding rocks, from the base of the palaeozoic series to the present time. We are thus carried back to a period so remote, that the appearance of the so-called primordial fauna (of Barrande) may by some be considered as a comparatively modern event." The Eozoon belongs to the most lowly organised of all classes of animals, but is highly organised for its class; it existed in countless numbers, and, as Dr. Dawson has remarked, certainly preyed on other minute organic beings, which must have lived in great numbers. Thus the words, which I wrote in 1859, about the existence of living beings long before the Cambrian period, and which are almost the same with those since used by Sir W. Logan, have proved true. Nevertheless, the difficulty of assigning any good reason for the absence of vast piles of strata rich in fossils beneath the Cambrian system is very great. It does not seem probable that the most ancient beds have been quite worn away by denudation, or that their fossils have been wholly obliterated by metamorphic action, for if this had been the case we should have found only small remnants of the formations next succeeding them in age, and these would always have existed in a partially metamorphosed condition. But the descriptions which we possess of the Silurian deposits over immense territories in Russia and in North America, do not support the view that the older a formation is the more invariably it has suffered extreme denudation and metamorphism. The case at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained. To show that it may hereafter receive some explanation, I will give the following hypothesis. From the nature of the organic remains which do not appear to have inhabited profound depths, in the several formations of Europe and of the United States; and from the amount of sediment, miles in thickness, of which the formations are composed, we may infer that from first to last large islands or tracts of land, whence the sediment was derived, occurred in the neighbourhood of the now existing continents of Europe and North America. This same view has since been maintained by Agassiz and others. But we do not know what was the state of things in the intervals between the several successive formations; whether Europe and the United States during these intervals existed as dry land, or as a submarine surface near land, on which sediment was not deposited, or as the bed of an open and unfathomable sea. Looking to the existing oceans, which are thrice as extensive as the land, we see them studded with many islands; but hardly one truly oceanic island (with the exception of New Zealand, if this can be called a truly oceanic island) is as yet known to afford even a remnant of any palaeozoic or secondary formation. Hence, we may perhaps infer, that during the palaeozoic and secondary periods, neither continents nor continental islands existed where our oceans now extend; for had they existed, palaeozoic and secondary formations would in all probability have been accumulated from sediment derived from their wear and tear; and would have been at least partially upheaved by the oscillations of level, which must have intervened during these enormously long periods. If, then, we may infer anything from these facts, we may infer that, where our oceans now extend, oceans have extended from the remotest period of which we have any record; and on the other hand, that where continents now exist, large tracts of land have existed, subjected, no doubt, to great oscillations of level, since the Cambrian period. The coloured map appended to my volume on Coral Reefs, led me to conclude that the great oceans are still mainly areas of subsidence, the great archipelagoes still areas of oscillations of level, and the continents areas of elevation. But we have no reason to assume that things have thus remained from the beginning of the world. Our continents seem to have been formed by a preponderance, during many oscillations of level, of the force of elevation. But may not the areas of preponderant movement have changed in the lapse of ages? At a period long antecedent to the Cambrian epoch, continents may have existed where oceans are now spread out, and clear and open oceans may have existed where our continents now stand. Nor should we be justified in assuming that if, for instance, the bed of the Pacific Ocean were now converted into a continent we should there find sedimentary formations, in recognisable condition, older than the Cambrian strata, supposing such to have been formerly deposited; for it might well happen that strata which had subsided some miles nearer to the centre of the earth, and which had been pressed on by an enormous weight of superincumbent water, might have undergone far more metamorphic action than strata which have always remained nearer to the surface. The immense areas in some parts of the world, for instance in South America, of naked metamorphic rocks, which must have been heated under great pressure, have always seemed to me to require some special explanation; and we may perhaps believe that we see in these large areas the many formations long anterior to the Cambrian epoch in a completely metamorphosed and denuded condition. The several difficulties here discussed, namely, that, though we find in our geological formations many links between the species which now exist and which formerly existed, we do not find infinitely numerous fine transitional forms closely joining them all together. The sudden manner in which several groups of species first appear in our European formations, the almost entire absence, as at present known, of formations rich in fossils beneath the Cambrian strata, are all undoubtedly of the most serious nature. We see this in the fact that the most eminent palaeontologists, namely, Cuvier, Agassiz, Barrande, Pictet, Falconer, E. Forbes, etc., and all our greatest geologists, as Lyell, Murchison, Sedgwick, etc., have unanimously, often vehemently, maintained the immutability of species. But Sir Charles Lyell now gives the support of his high authority to the opposite side, and most geologists and palaeontologists are much shaken in their former belief. Those who believe that the geological record is in any degree perfect, will undoubtedly at once reject my theory. For my part, following out Lyell's metaphor, I look at the geological record as a history of the world imperfectly kept and written in a changing dialect. Of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved, and of each page, only here and there a few lines. Each word of the slowly-changing language, more or less different in the successive chapters, may represent the forms of life, which are entombed in our consecutive formations, and which falsely appear to have been abruptly introduced. On this view the difficulties above discussed are greatly diminished or even disappear. CHAPTER XI. ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS. On the slow and successive appearance of new species--On their different rates of change--Species once lost do not reappear--Groups of species follow the same general rules in their appearance and disappearance as do single species--On extinction--On simultaneous changes in the forms of life throughout the world--On the affinities of extinct species to each other and to living species--On the state of development of ancient forms--On the succession of the same types within the same areas--Summary of preceding and present chapters. Let us now see whether the several facts and laws relating to the geological succession of organic beings accord best with the common view of the immutability of species, or with that of their slow and gradual modification, through variation and natural selection. New species have appeared very slowly, one after another, both on the land and in the waters. Lyell has shown that it is hardly possible to resist the evidence on this head in the case of the several tertiary stages; and every year tends to fill up the blanks between the stages, and to make the proportion between the lost and existing forms more gradual. In some of the most recent beds, though undoubtedly of high antiquity if measured by years, only one or two species are extinct, and only one or two are new, having appeared there for the first time, either locally, or, as far as we know, on the face of the earth. The secondary formations are more broken; but, as Bronn has remarked, neither the appearance nor disappearance of the many species embedded in each formation has been simultaneous. Species belonging to different genera and classes have not changed at the same rate, or in the same degree. In the older tertiary beds a few living shells may still be found in the midst of a multitude of extinct forms. Falconer has given a striking instance of a similar fact, for an existing crocodile is associated with many lost mammals and reptiles in the sub-Himalayan deposits. The Silurian Lingula differs but little from the living species of this genus; whereas most of the other Silurian Molluscs and all the Crustaceans have changed greatly. The productions of the land seem to have changed at a quicker rate than those of the sea, of which a striking instance has been observed in Switzerland. There is some reason to believe that organisms high in the scale, change more quickly than those that are low: though there are exceptions to this rule. The amount of organic change, as Pictet has remarked, is not the same in each successive so-called formation. Yet if we compare any but the most closely related formations, all the species will be found to have undergone some change. When a species has once disappeared from the face of the earth, we have no reason to believe that the same identical form ever reappears. The strongest apparent exception to this latter rule is that of the so-called "colonies" of M. Barrande, which intrude for a period in the midst of an older formation, and then allow the pre-existing fauna to reappear; but Lyell's explanation, namely, that it is a case of temporary migration from a distinct geographical province, seems satisfactory. These several facts accord well with our theory, which includes no fixed law of development, causing all the inhabitants of an area to change abruptly, or simultaneously, or to an equal degree. The process of modification must be slow, and will generally affect only a few species at the same time; for the variability of each species is independent of that of all others. Whether such variations or individual differences as may arise will be accumulated through natural selection in a greater or less degree, thus causing a greater or less amount of permanent modification, will depend on many complex contingencies--on the variations being of a beneficial nature, on the freedom of intercrossing, on the slowly changing physical conditions of the country, on the immigration of new colonists, and on the nature of the other inhabitants with which the varying species come into competition. Hence it is by no means surprising that one species should retain the same identical form much longer than others; or, if changing, should change in a less degree. We find similar relations between the existing inhabitants of distinct countries; for instance, the land-shells and coleopterous insects of Madeira have come to differ considerably from their nearest allies on the continent of Europe, whereas the marine shells and birds have remained unaltered. We can perhaps understand the apparently quicker rate of change in terrestrial and in more highly organised productions compared with marine and lower productions, by the more complex relations of the higher beings to their organic and inorganic conditions of life, as explained in a former chapter. When many of the inhabitants of any area have become modified and improved, we can understand, on the principle of competition, and from the all-important relations of organism to organism in the struggle for life, that any form which did not become in some degree modified and improved, would be liable to extermination. Hence, we see why all the species in the same region do at last, if we look to long enough intervals of time, become modified; for otherwise they would become extinct. In members of the same class the average amount of change, during long and equal periods of time, may, perhaps, be nearly the same; but as the accumulation of enduring formations, rich in fossils, depends on great masses of sediment being deposited on subsiding areas, our formations have been almost necessarily accumulated at wide and irregularly intermittent intervals of time; consequently the amount of organic change exhibited by the fossils embedded in consecutive formations is not equal. Each formation, on this view, does not mark a new and complete act of creation, but only an occasional scene, taken almost at hazard, in an ever slowly changing drama. We can clearly understand why a species when once lost should never reappear, even if the very same conditions of life, organic and inorganic, should recur. For though the offspring of one species might be adapted (and no doubt this has occurred in innumerable instances) to fill the place of another species in the economy of nature, and thus supplant it; yet the two forms--the old and the new--would not be identically the same; for both would almost certainly inherit different characters from their distinct progenitors; and organisms already differing would vary in a different manner. For instance, it is possible, if all our fantail-pigeons were destroyed, that fanciers might make a new breed hardly distinguishable from the present breed; but if the parent rock-pigeon were likewise destroyed, and under nature we have every reason to believe that parent forms are generally supplanted and exterminated by their improved offspring, it is incredible that a fantail, identical with the existing breed, could be raised from any other species of pigeon, or even from any other well established race of the domestic pigeon, for the successive variations would almost certainly be in some degree different, and the newly-formed variety would probably inherit from its progenitor some characteristic differences. Groups of species, that is, genera and families, follow the same general rules in their appearance and disappearance as do single species, changing more or less quickly, and in a greater or lesser degree. A group, when it has once disappeared, never reappears; that is, its existence, as long as it lasts, is continuous. I am aware that there are some apparent exceptions to this rule, but the exceptions are surprisingly few, so few that E. Forbes, Pictet, and Woodward (though all strongly opposed to such views as I maintain) admit its truth; and the rule strictly accords with the theory. For all the species of the same group, however long it may have lasted, are the modified descendants one from the other, and all from a common progenitor. In the genus Lingula, for instance, the species which have successively appeared at all ages must have been connected by an unbroken series of generations, from the lowest Silurian stratum to the present day. We have seen in the last chapter that whole groups of species sometimes falsely appear to have been abruptly developed; and I have attempted to give an explanation of this fact, which if true would be fatal to my views. But such cases are certainly exceptional; the general rule being a gradual increase in number, until the group reaches its maximum, and then, sooner or later, a gradual decrease. If the number of the species included within a genus, or the number of the genera within a family, be represented by a vertical line of varying thickness, ascending through the successive geological formations, in which the species are found, the line will sometimes falsely appear to begin at its lower end, not in a sharp point, but abruptly; it then gradually thickens upwards, often keeping of equal thickness for a space, and ultimately thins out in the upper beds, marking the decrease and final extinction of the species. This gradual increase in number of the species of a group is strictly conformable with the theory; for the species of the same genus, and the genera of the same family, can increase only slowly and progressively; the process of modification and the production of a number of allied forms necessarily being a slow and gradual process, one species first giving rise to two or three varieties, these being slowly converted into species, which in their turn produce by equally slow steps other varieties and species, and so on, like the branching of a great tree from a single stem, till the group becomes large. ON EXTINCTION. We have as yet only spoken incidentally of the disappearance of species and of groups of species. On the theory of natural selection, the extinction of old forms and the production of new and improved forms are intimately connected together. The old notion of all the inhabitants of the earth having been swept away by catastrophes at successive periods is very generally given up, even by those geologists, as Elie de Beaumont, Murchison, Barrande, etc., whose general views would naturally lead them to this conclusion. On the contrary, we have every reason to believe, from the study of the tertiary formations, that species and groups of species gradually disappear, one after another, first from one spot, then from another, and finally from the world. In some few cases, however, as by the breaking of an isthmus and the consequent irruption of a multitude of new inhabitants into an adjoining sea, or by the final subsidence of an island, the process of extinction may have been rapid. Both single species and whole groups of species last for very unequal periods; some groups, as we have seen, have endured from the earliest known dawn of life to the present day; some have disappeared before the close of the palaeozoic period. No fixed law seems to determine the length of time during which any single species or any single genus endures. There is reason to believe that the extinction of a whole group of species is generally a slower process than their production: if their appearance and disappearance be represented, as before, by a vertical line of varying thickness the line is found to taper more gradually at its upper end, which marks the progress of extermination, than at its lower end, which marks the first appearance and the early increase in number of the species. In some cases, however, the extermination of whole groups, as of ammonites, towards the close of the secondary period, has been wonderfully sudden. The extinction of species has been involved in the most gratuitous mystery. Some authors have even supposed that, as the individual has a definite length of life, so have species a definite duration. No one can have marvelled more than I have done at the extinction of species. When I found in La Plata the tooth of a horse embedded with the remains of Mastodon, Megatherium, Toxodon and other extinct monsters, which all co-existed with still living shells at a very late geological period, I was filled with astonishment; for, seeing that the horse, since its introduction by the Spaniards into South America, has run wild over the whole country and has increased in numbers at an unparalleled rate, I asked myself what could so recently have exterminated the former horse under conditions of life apparently so favourable. But my astonishment was groundless. Professor Owen soon perceived that the tooth, though so like that of the existing horse, belonged to an extinct species. Had this horse been still living, but in some degree rare, no naturalist would have felt the least surprise at its rarity; for rarity is the attribute of a vast number of species of all classes, in all countries. If we ask ourselves why this or that species is rare, we answer that something is unfavourable in its conditions of life; but what that something is, we can hardly ever tell. On the supposition of the fossil horse still existing as a rare species, we might have felt certain, from the analogy of all other mammals, even of the slow-breeding elephant, and from the history of the naturalisation of the domestic horse in South America, that under more favourable conditions it would in a very few years have stocked the whole continent. But we could not have told what the unfavourable conditions were which checked its increase, whether some one or several contingencies, and at what period of the horse's life, and in what degree they severally acted. If the conditions had gone on, however slowly, becoming less and less favourable, we assuredly should not have perceived the fact, yet the fossil horse would certainly have become rarer and rarer, and finally extinct--its place being seized on by some more successful competitor. It is most difficult always to remember that the increase of every living creature is constantly being checked by unperceived hostile agencies; and that these same unperceived agencies are amply sufficient to cause rarity, and finally extinction. So little is this subject understood, that I have heard surprise repeatedly expressed at such great monsters as the Mastodon and the more ancient Dinosaurians having become extinct; as if mere bodily strength gave victory in the battle of life. Mere size, on the contrary, would in some cases determine, as has been remarked by Owen, quicker extermination, from the greater amount of requisite food. Before man inhabited India or Africa, some cause must have checked the continued increase of the existing elephant. A highly capable judge, Dr. Falconer, believes that it is chiefly insects which, from incessantly harassing and weakening the elephant in India, check its increase; and this was Bruce's conclusion with respect to the African elephant in Abyssinia. It is certain that insects and blood-sucking bats determine the existence of the larger naturalised quadrupeds in several parts of South America. We see in many cases in the more recent tertiary formations that rarity precedes extinction; and we know that this has been the progress of events with those animals which have been exterminated, either locally or wholly, through man's agency. I may repeat what I published in 1845, namely, that to admit that species generally become rare before they become extinct--to feel no surprise at the rarity of a species, and yet to marvel greatly when the species ceases to exist, is much the same as to admit that sickness in the individual is the forerunner of death--to feel no surprise at sickness, but, when the sick man dies, to wonder and to suspect that he died by some deed of violence. The theory of natural selection is grounded on the belief that each new variety and ultimately each new species, is produced and maintained by having some advantage over those with which it comes into competition; and the consequent extinction of less-favoured forms almost inevitably follows. It is the same with our domestic productions: when a new and slightly improved variety has been raised, it at first supplants the less improved varieties in the same neighbourhood; when much improved it is transported far and near, like our short-horn cattle, and takes the place of other breeds in other countries. Thus the appearance of new forms and the disappearance of old forms, both those naturally and artificially produced, are bound together. In flourishing groups, the number of new specific forms which have been produced within a given time has at some periods probably been greater than the number of the old specific forms which have been exterminated; but we know that species have not gone on indefinitely increasing, at least during the later geological epochs, so that, looking to later times, we may believe that the production of new forms has caused the extinction of about the same number of old forms. The competition will generally be most severe, as formerly explained and illustrated by examples, between the forms which are most like each other in all respects. Hence the improved and modified descendants of a species will generally cause the extermination of the parent-species; and if many new forms have been developed from any one species, the nearest allies of that species, i.e. the species of the same genus, will be the most liable to extermination. Thus, as I believe, a number of new species descended from one species, that is a new genus, comes to supplant an old genus, belonging to the same family. But it must often have happened that a new species belonging to some one group has seized on the place occupied by a species belonging to a distinct group, and thus have caused its extermination. If many allied forms be developed from the successful intruder, many will have to yield their places; and it will generally be the allied forms, which will suffer from some inherited inferiority in common. But whether it be species belonging to the same or to a distinct class, which have yielded their places to other modified and improved species, a few of the sufferers may often be preserved for a long time, from being fitted to some peculiar line of life, or from inhabiting some distant and isolated station, where they will have escaped severe competition. For instance, some species of Trigonia, a great genus of shells in the secondary formations, survive in the Australian seas; and a few members of the great and almost extinct group of Ganoid fishes still inhabit our fresh waters. Therefore, the utter extinction of a group is generally, as we have seen, a slower process than its production. With respect to the apparently sudden extermination of whole families or orders, as of Trilobites at the close of the palaeozoic period, and of Ammonites at the close of the secondary period, we must remember what has been already said on the probable wide intervals of time between our consecutive formations; and in these intervals there may have been much slow extermination. Moreover, when, by sudden immigration or by unusually rapid development, many species of a new group have taken possession of an area, many of the older species will have been exterminated in a correspondingly rapid manner; and the forms which thus yield their places will commonly be allied, for they will partake of the same inferiority in common. Thus, as it seems to me, the manner in which single species and whole groups of species become extinct accords well with the theory of natural selection. We need not marvel at extinction; if we must marvel, let it be at our presumption in imagining for a moment that we understand the many complex contingencies on which the existence of each species depends. If we forget for an instant that each species tends to increase inordinately, and that some check is always in action, yet seldom perceived by us, the whole economy of nature will be utterly obscured. Whenever we can precisely say why this species is more abundant in individuals than that; why this species and not another can be naturalised in a given country; then, and not until then, we may justly feel surprise why we cannot account for the extinction of any particular species or group of species. ON THE FORMS OF LIFE CHANGING ALMOST SIMULTANEOUSLY THROUGHOUT THE WORLD. Scarcely any palaeontological discovery is more striking than the fact that the forms of life change almost simultaneously throughout the world. Thus our European Chalk formation can be recognised in many distant regions, under the most different climates, where not a fragment of the mineral chalk itself can be found; namely, in North America, in equatorial South America, in Tierra del Fuego, at the Cape of Good Hope, and in the peninsula of India. For at these distant points, the organic remains in certain beds present an unmistakable resemblance to those of the Chalk. It is not that the same species are met with; for in some cases not one species is identically the same, but they belong to the same families, genera, and sections of genera, and sometimes are similarly characterised in such trifling points as mere superficial sculpture. Moreover, other forms, which are not found in the Chalk of Europe, but which occur in the formations either above or below, occur in the same order at these distant points of the world. In the several successive palaeozoic formations of Russia, Western Europe and North America, a similar parallelism in the forms of life has been observed by several authors; so it is, according to Lyell, with the European and North American tertiary deposits. Even if the few fossil species which are common to the Old and New Worlds were kept wholly out of view, the general parallelism in the successive forms of life, in the palaeozoic and tertiary stages, would still be manifest, and the several formations could be easily correlated. These observations, however, relate to the marine inhabitants of the world: we have not sufficient data to judge whether the productions of the land and of fresh water at distant points change in the same parallel manner. We may doubt whether they have thus changed: if the Megatherium, Mylodon, Macrauchenia, and Toxodon had been brought to Europe from La Plata, without any information in regard to their geological position, no one would have suspected that they had co-existed with sea-shells all still living; but as these anomalous monsters co-existed with the Mastodon and Horse, it might at least have been inferred that they had lived during one of the later tertiary stages. When the marine forms of life are spoken of as having changed simultaneously throughout the world, it must not be supposed that this expression relates to the same year, or even to the same century, or even that it has a very strict geological sense; for if all the marine animals now living in Europe, and all those that lived in Europe during the pleistocene period (a very remote period as measured by years, including the whole glacial epoch) were compared with those now existing in South America or in Australia, the most skilful naturalist would hardly be able to say whether the present or the pleistocene inhabitants of Europe resembled most closely those of the southern hemisphere. So, again, several highly competent observers maintain that the existing productions of the United States are more closely related to those which lived in Europe during certain late tertiary stages, than to the present inhabitants of Europe; and if this be so, it is evident that fossiliferous beds now deposited on the shores of North America would hereafter be liable to be classed with somewhat older European beds. Nevertheless, looking to a remotely future epoch, there can be little doubt that all the more modern MARINE formations, namely, the upper pliocene, the pleistocene and strictly modern beds of Europe, North and South America, and Australia, from containing fossil remains in some degree allied, and from not including those forms which are found only in the older underlying deposits, would be correctly ranked as simultaneous in a geological sense. The fact of the forms of life changing simultaneously in the above large sense, at distant parts of the world, has greatly struck those admirable observers, MM. de Verneuil and d'Archiac. After referring to the parallelism of the palaeozoic forms of life in various parts of Europe, they add, "If struck by this strange sequence, we turn our attention to North America, and there discover a series of analogous phenomena, it will appear certain that all these modifications of species, their extinction, and the introduction of new ones, cannot be owing to mere changes in marine currents or other causes more or less local and temporary, but depend on general laws which govern the whole animal kingdom." M. Barrande has made forcible remarks to precisely the same effect. It is, indeed, quite futile to look to changes of currents, climate, or other physical conditions, as the cause of these great mutations in the forms of life throughout the world, under the most different climates. We must, as Barrande has remarked, look to some special law. We shall see this more clearly when we treat of the present distribution of organic beings, and find how slight is the relation between the physical conditions of various countries and the nature of their inhabitants. This great fact of the parallel succession of the forms of life throughout the world, is explicable on the theory of natural selection. New species are formed by having some advantage over older forms; and the forms, which are already dominant, or have some advantage over the other forms in their own country, give birth to the greatest number of new varieties or incipient species. We have distinct evidence on this head, in the plants which are dominant, that is, which are commonest and most widely diffused, producing the greatest number of new varieties. It is also natural that the dominant, varying and far-spreading species, which have already invaded, to a certain extent, the territories of other species, should be those which would have the best chance of spreading still further, and of giving rise in new countries to other new varieties and species. The process of diffusion would often be very slow, depending on climatal and geographical changes, on strange accidents, and on the gradual acclimatization of new species to the various climates through which they might have to pass, but in the course of time the dominant forms would generally succeed in spreading and would ultimately prevail. The diffusion would, it is probable, be slower with the terrestrial inhabitants of distinct continents than with the marine inhabitants of the continuous sea. We might therefore expect to find, as we do find, a less strict degree of parallelism in the succession of the productions of the land than with those of the sea. Thus, as it seems to me, the parallel, and, taken in a large sense, simultaneous, succession of the same forms of life throughout the world, accords well with the principle of new species having been formed by dominant species spreading widely and varying; the new species thus produced being themselves dominant, owing to their having had some advantage over their already dominant parents, as well as over other species; and again spreading, varying, and producing new forms. The old forms which are beaten and which yield their places to the new and victorious forms, will generally be allied in groups, from inheriting some inferiority in common; and, therefore, as new and improved groups spread throughout the world, old groups disappear from the world; and the succession of forms everywhere tends to correspond both in their first appearance and final disappearance. There is one other remark connected with this subject worth making. I have given my reasons for believing that most of our great formations, rich in fossils, were deposited during periods of subsidence; and that blank intervals of vast duration, as far as fossils are concerned, occurred during the periods when the bed of the sea was either stationary or rising, and likewise when sediment was not thrown down quickly enough to embed and preserve organic remains. During these long and blank intervals I suppose that the inhabitants of each region underwent a considerable amount of modification and extinction, and that there was much migration from other parts of the world. As we have reason to believe that large areas are affected by the same movement, it is probable that strictly contemporaneous formations have often been accumulated over very wide spaces in the same quarter of the world; but we are very far from having any right to conclude that this has invariably been the case, and that large areas have invariably been affected by the same movements. When two formations have been deposited in two regions during nearly, but not exactly, the same period, we should find in both, from the causes explained in the foregoing paragraphs, the same general succession in the forms of life; but the species would not exactly correspond; for there will have been a little more time in the one region than in the other for modification, extinction, and immigration. I suspect that cases of this nature occur in Europe. Mr. Prestwich, in his admirable Memoirs on the eocene deposits of England and France, is able to draw a close general parallelism between the successive stages in the two countries; but when he compares certain stages in England with those in France, although he finds in both a curious accordance in the numbers of the species belonging to the same genera, yet the species themselves differ in a manner very difficult to account for considering the proximity of the two areas, unless, indeed, it be assumed that an isthmus separated two seas inhabited by distinct, but contemporaneous faunas. Lyell has made similar observations on some of the later tertiary formations. Barrande, also, shows that there is a striking general parallelism in the successive Silurian deposits of Bohemia and Scandinavia; nevertheless he finds a surprising amount of difference in the species. If the several formations in these regions have not been deposited during the same exact periods--a formation in one region often corresponding with a blank interval in the other--and if in both regions the species have gone on slowly changing during the accumulation of the several formations and during the long intervals of time between them; in this case the several formations in the two regions could be arranged in the same order, in accordance with the general succession of the forms of life, and the order would falsely appear to be strictly parallel; nevertheless the species would not all be the same in the apparently corresponding stages in the two regions. ON THE AFFINITIES OF EXTINCT SPECIES TO EACH OTHER, AND TO LIVING FORMS. Let us now look to the mutual affinities of extinct and living species. All fall into a few grand classes; and this fact is at once explained on the principle of descent. The more ancient any form is, the more, as a general rule, it differs from living forms. But, as Buckland long ago remarked, extinct species can all be classed either in still existing groups, or between them. That the extinct forms of life help to fill up the intervals between existing genera, families, and orders, is certainly true; but as this statement has often been ignored or even denied, it may be well to make some remarks on this subject, and to give some instances. If we confine our attention either to the living or to the extinct species of the same class, the series is far less perfect than if we combine both into one general system. In the writings of Professor Owen we continually meet with the expression of generalised forms, as applied to extinct animals; and in the writings of Agassiz, of prophetic or synthetic types; and these terms imply that such forms are, in fact, intermediate or connecting links. Another distinguished palaeontologist, M. Gaudry, has shown in the most striking manner that many of the fossil mammals discovered by him in Attica serve to break down the intervals between existing genera. Cuvier ranked the Ruminants and Pachyderms as two of the most distinct orders of mammals; but so many fossil links have been disentombed that Owen has had to alter the whole classification, and has placed certain Pachyderms in the same sub-order with ruminants; for example, he dissolves by gradations the apparently wide interval between the pig and the camel. The Ungulata or hoofed quadrupeds are now divided into the even-toed or odd-toed divisions; but the Macrauchenia of South America connects to a certain extent these two grand divisions. No one will deny that the Hipparion is intermediate between the existing horse and certain other ungulate forms. What a wonderful connecting link in the chain of mammals is the Typotherium from South America, as the name given to it by Professor Gervais expresses, and which cannot be placed in any existing order. The Sirenia form a very distinct group of the mammals, and one of the most remarkable peculiarities in existing dugong and lamentin is the entire absence of hind limbs, without even a rudiment being left; but the extinct Halitherium had, according to Professor Flower, an ossified thigh-bone "articulated to a well-defined acetabulum in the pelvis," and it thus makes some approach to ordinary hoofed quadrupeds, to which the Sirenia are in other respects allied. The cetaceans or whales are widely different from all other mammals, but the tertiary Zeuglodon and Squalodon, which have been placed by some naturalists in an order by themselves, are considered by Professor Huxley to be undoubtedly cetaceans, "and to constitute connecting links with the aquatic carnivora." Even the wide interval between birds and reptiles has been shown by the naturalist just quoted to be partially bridged over in the most unexpected manner, on the one hand, by the ostrich and extinct Archeopteryx, and on the other hand by the Compsognathus, one of the Dinosaurians--that group which includes the most gigantic of all terrestrial reptiles. Turning to the Invertebrata, Barrande asserts, a higher authority could not be named, that he is every day taught that, although palaeozoic animals can certainly be classed under existing groups, yet that at this ancient period the groups were not so distinctly separated from each other as they now are. Some writers have objected to any extinct species, or group of species, being considered as intermediate between any two living species, or groups of species. If by this term it is meant that an extinct form is directly intermediate in all its characters between two living forms or groups, the objection is probably valid. But in a natural classification many fossil species certainly stand between living species, and some extinct genera between living genera, even between genera belonging to distinct families. The most common case, especially with respect to very distinct groups, such as fish and reptiles, seems to be that, supposing them to be distinguished at the present day by a score of characters, the ancient members are separated by a somewhat lesser number of characters, so that the two groups formerly made a somewhat nearer approach to each other than they now do. It is a common belief that the more ancient a form is, by so much the more it tends to connect by some of its characters groups now widely separated from each other. This remark no doubt must be restricted to those groups which have undergone much change in the course of geological ages; and it would be difficult to prove the truth of the proposition, for every now and then even a living animal, as the Lepidosiren, is discovered having affinities directed towards very distinct groups. Yet if we compare the older Reptiles and Batrachians, the older Fish, the older Cephalopods, and the eocene Mammals, with the recent members of the same classes, we must admit that there is truth in the remark. Let us see how far these several facts and inferences accord with the theory of descent with modification. As the subject is somewhat complex, I must request the reader to turn to the diagram in the fourth chapter. We may suppose that the numbered letters in italics represent genera, and the dotted lines diverging from them the species in each genus. The diagram is much too simple, too few genera and too few species being given, but this is unimportant for us. The horizontal lines may represent successive geological formations, and all the forms beneath the uppermost line may be considered as extinct. The three existing genera, a14, q14, p14, will form a small family; b14 and f14, a closely allied family or subfamily; and o14, i14, m14, a third family. These three families, together with the many extinct genera on the several lines of descent diverging from the parent form (A) will form an order; for all will have inherited something in common from their ancient progenitor. On the principle of the continued tendency to divergence of character, which was formerly illustrated by this diagram, the more recent any form is the more it will generally differ from its ancient progenitor. Hence, we can understand the rule that the most ancient fossils differ most from existing forms. We must not, however, assume that divergence of character is a necessary contingency; it depends solely on the descendants from a species being thus enabled to seize on many and different places in the economy of nature. Therefore it is quite possible, as we have seen in the case of some Silurian forms, that a species might go on being slightly modified in relation to its slightly altered conditions of life, and yet retain throughout a vast period the same general characteristics. This is represented in the diagram by the letter F14. All the many forms, extinct and recent, descended from (A), make, as before remarked, one order; and this order, from the continued effects of extinction and divergence of character, has become divided into several sub-families and families, some of which are supposed to have perished at different periods, and some to have endured to the present day. By looking at the diagram we can see that if many of the extinct forms supposed to be embedded in the successive formations, were discovered at several points low down in the series, the three existing families on the uppermost line would be rendered less distinct from each other. If, for instance, the genera a1, a5, a10, f8, m3, m6, m9, were disinterred, these three families would be so closely linked together that they probably would have to be united into one great family, in nearly the same manner as has occurred with ruminants and certain pachyderms. Yet he who objected to consider as intermediate the extinct genera, which thus link together the living genera of three families, would be partly justified, for they are intermediate, not directly, but only by a long and circuitous course through many widely different forms. If many extinct forms were to be discovered above one of the middle horizontal lines or geological formations--for instance, above No. VI.--but none from beneath this line, then only two of the families (those on the left hand a14, etc., and b14, etc.) would have to be united into one; and there would remain two families which would be less distinct from each other than they were before the discovery of the fossils. So again, if the three families formed of eight genera (a14 to m14), on the uppermost line, be supposed to differ from each other by half-a-dozen important characters, then the families which existed at a period marked VI would certainly have differed from each other by a less number of characters; for they would at this early stage of descent have diverged in a less degree from their common progenitor. Thus it comes that ancient and extinct genera are often in a greater or less degree intermediate in character between their modified descendants, or between their collateral relations. Under nature the process will be far more complicated than is represented in the diagram; for the groups will have been more numerous; they will have endured for extremely unequal lengths of time, and will have been modified in various degrees. As we possess only the last volume of the geological record, and that in a very broken condition, we have no right to expect, except in rare cases, to fill up the wide intervals in the natural system, and thus to unite distinct families or orders. All that we have a right to expect is, that those groups which have, within known geological periods, undergone much modification, should in the older formations make some slight approach to each other; so that the older members should differ less from each other in some of their characters than do the existing members of the same groups; and this by the concurrent evidence of our best palaeontologists is frequently the case. Thus, on the theory of descent with modification, the main facts with respect to the mutual affinities of the extinct forms of life to each other and to living forms, are explained in a satisfactory manner. And they are wholly inexplicable on any other view. On this same theory, it is evident that the fauna during any one great period in the earth's history will be intermediate in general character between that which preceded and that which succeeded it. Thus the species which lived at the sixth great stage of descent in the diagram are the modified offspring of those which lived at the fifth stage, and are the parents of those which became still more modified at the seventh stage; hence they could hardly fail to be nearly intermediate in character between the forms of life above and below. We must, however, allow for the entire extinction of some preceding forms, and in any one region for the immigration of new forms from other regions, and for a large amount of modification during the long and blank intervals between the successive formations. Subject to these allowances, the fauna of each geological period undoubtedly is intermediate in character, between the preceding and succeeding faunas. I need give only one instance, namely, the manner in which the fossils of the Devonian system, when this system was first discovered, were at once recognised by palaeontologists as intermediate in character between those of the overlying carboniferous and underlying Silurian systems. But each fauna is not necessarily exactly intermediate, as unequal intervals of time have elapsed between consecutive formations. It is no real objection to the truth of the statement that the fauna of each period as a whole is nearly intermediate in character between the preceding and succeeding faunas, that certain genera offer exceptions to the rule. For instance, the species of mastodons and elephants, when arranged by Dr. Falconer in two series--in the first place according to their mutual affinities, and in the second place according to their periods of existence--do not accord in arrangement. The species extreme in character are not the oldest or the most recent; nor are those which are intermediate in character, intermediate in age. But supposing for an instant, in this and other such cases, that the record of the first appearance and disappearance of the species was complete, which is far from the case, we have no reason to believe that forms successively produced necessarily endure for corresponding lengths of time. A very ancient form may occasionally have lasted much longer than a form elsewhere subsequently produced, especially in the case of terrestrial productions inhabiting separated districts. To compare small things with great; if the principal living and extinct races of the domestic pigeon were arranged in serial affinity, this arrangement would not closely accord with the order in time of their production, and even less with the order of their disappearance; for the parent rock-pigeon still lives; and many varieties between the rock-pigeon and the carrier have become extinct; and carriers which are extreme in the important character of length of beak originated earlier than short-beaked tumblers, which are at the opposite end of the series in this respect. Closely connected with the statement, that the organic remains from an intermediate formation are in some degree intermediate in character, is the fact, insisted on by all palaeontologists, that fossils from two consecutive formations are far more closely related to each other, than are the fossils from two remote formations. Pictet gives as a well-known instance, the general resemblance of the organic remains from the several stages of the Chalk formation, though the species are distinct in each stage. This fact alone, from its generality, seems to have shaken Professor Pictet in his belief in the immutability of species. He who is acquainted with the distribution of existing species over the globe, will not attempt to account for the close resemblance of distinct species in closely consecutive formations, by the physical conditions of the ancient areas having remained nearly the same. Let it be remembered that the forms of life, at least those inhabiting the sea, have changed almost simultaneously throughout the world, and therefore under the most different climates and conditions. Consider the prodigious vicissitudes of climate during the pleistocene period, which includes the whole glacial epoch, and note how little the specific forms of the inhabitants of the sea have been affected. On the theory of descent, the full meaning of the fossil remains from closely consecutive formations, being closely related, though ranked as distinct species, is obvious. As the accumulation of each formation has often been interrupted, and as long blank intervals have intervened between successive formations, we ought not to expect to find, as I attempted to show in the last chapter, in any one or in any two formations, all the intermediate varieties between the species which appeared at the commencement and close of these periods: but we ought to find after intervals, very long as measured by years, but only moderately long as measured geologically, closely allied forms, or, as they have been called by some authors, representative species; and these assuredly we do find. We find, in short, such evidence of the slow and scarcely sensible mutations of specific forms, as we have the right to expect. ON THE STATE OF DEVELOPMENT OF ANCIENT COMPARED WITH LIVING FORMS. We have seen in the fourth chapter that the degree of differentiation and specialisation of the parts in organic beings, when arrived at maturity, is the best standard, as yet suggested, of their degree of perfection or highness. We have also seen that, as the specialisation of parts is an advantage to each being, so natural selection will tend to render the organisation of each being more specialised and perfect, and in this sense higher; not but that it may leave many creatures with simple and unimproved structures fitted for simple conditions of life, and in some cases will even degrade or simplify the organisation, yet leaving such degraded beings better fitted for their new walks of life. In another and more general manner, new species become superior to their predecessors; for they have to beat in the struggle for life all the older forms, with which they come into close competition. We may therefore conclude that if under a nearly similar climate the eocene inhabitants of the world could be put into competition with the existing inhabitants, the former would be beaten and exterminated by the latter, as would the secondary by the eocene, and the palaeozoic by the secondary forms. So that by this fundamental test of victory in the battle for life, as well as by the standard of the specialisation of organs, modern forms ought, on the theory of natural selection, to stand higher than ancient forms. Is this the case? A large majority of palaeontologists would answer in the affirmative; and it seems that this answer must be admitted as true, though difficult of proof. It is no valid objection to this conclusion, that certain Brachiopods have been but slightly modified from an extremely remote geological epoch; and that certain land and fresh-water shells have remained nearly the same, from the time when, as far as is known, they first appeared. It is not an insuperable difficulty that Foraminifera have not, as insisted on by Dr. Carpenter, progressed in organisation since even the Laurentian epoch; for some organisms would have to remain fitted for simple conditions of life, and what could be better fitted for this end than these lowly organised Protozoa? Such objections as the above would be fatal to my view, if it included advance in organisation as a necessary contingent. They would likewise be fatal, if the above Foraminifera, for instance, could be proved to have first come into existence during the Laurentian epoch, or the above Brachiopods during the Cambrian formation; for in this case, there would not have been time sufficient for the development of these organisms up to the standard which they had then reached. When advanced up to any given point, there is no necessity, on the theory of natural selection, for their further continued process; though they will, during each successive age, have to be slightly modified, so as to hold their places in relation to slight changes in their conditions. The foregoing objections hinge on the question whether we really know how old the world is, and at what period the various forms of life first appeared; and this may well be disputed. The problem whether organisation on the whole has advanced is in many ways excessively intricate. The geological record, at all times imperfect, does not extend far enough back to show with unmistakable clearness that within the known history of the world organisation has largely advanced. Even at the present day, looking to members of the same class, naturalists are not unanimous which forms ought to be ranked as highest: thus, some look at the selaceans or sharks, from their approach in some important points of structure to reptiles, as the highest fish; others look at the teleosteans as the highest. The ganoids stand intermediate between the selaceans and teleosteans; the latter at the present day are largely preponderant in number; but formerly selaceans and ganoids alone existed; and in this case, according to the standard of highness chosen, so will it be said that fishes have advanced or retrograded in organisation. To attempt to compare members of distinct types in the scale of highness seems hopeless; who will decide whether a cuttle-fish be higher than a bee--that insect which the great Von Baer believed to be "in fact more highly organised than a fish, although upon another type?" In the complex struggle for life it is quite credible that crustaceans, not very high in their own class, might beat cephalopods, the highest molluscs; and such crustaceans, though not highly developed, would stand very high in the scale of invertebrate animals, if judged by the most decisive of all trials--the law of battle. Beside these inherent difficulties in deciding which forms are the most advanced in organisation, we ought not solely to compare the highest members of a class at any two periods--though undoubtedly this is one and perhaps the most important element in striking a balance--but we ought to compare all the members, high and low, at two periods. At an ancient epoch the highest and lowest molluscoidal animals, namely, cephalopods and brachiopods, swarmed in numbers; at the present time both groups are greatly reduced, while others, intermediate in organisation, have largely increased; consequently some naturalists maintain that molluscs were formerly more highly developed than at present; but a stronger case can be made out on the opposite side, by considering the vast reduction of brachiopods, and the fact that our existing cephalopods, though few in number, are more highly organised than their ancient representatives. We ought also to compare the relative proportional numbers, at any two periods, of the high and low classes throughout the world: if, for instance, at the present day fifty thousand kinds of vertebrate animals exist, and if we knew that at some former period only ten thousand kinds existed, we ought to look at this increase in number in the highest class, which implies a great displacement of lower forms, as a decided advance in the organisation of the world. We thus see how hopelessly difficult it is to compare with perfect fairness, under such extremely complex relations, the standard of organisation of the imperfectly-known faunas of successive periods. We shall appreciate this difficulty more clearly by looking to certain existing faunas and floras. From the extraordinary manner in which European productions have recently spread over New Zealand, and have seized on places which must have been previously occupied by the indigenes, we must believe, that if all the animals and plants of Great Britain were set free in New Zealand, a multitude of British forms would in the course of time become thoroughly naturalized there, and would exterminate many of the natives. On the other hand, from the fact that hardly a single inhabitant of the southern hemisphere has become wild in any part of Europe, we may well doubt whether, if all the productions of New Zealand were set free in Great Britain, any considerable number would be enabled to seize on places now occupied by our native plants and animals. Under this point of view, the productions of Great Britain stand much higher in the scale than those of New Zealand. Yet the most skilful naturalist, from an examination of the species of the two countries, could not have foreseen this result. Agassiz and several other highly competent judges insist that ancient animals resemble to a certain extent the embryos of recent animals belonging to the same classes; and that the geological succession of extinct forms is nearly parallel with the embryological development of existing forms. This view accords admirably well with our theory. In a future chapter I shall attempt to show that the adult differs from its embryo, owing to variations having supervened at a not early age, and having been inherited at a corresponding age. This process, whilst it leaves the embryo almost unaltered, continually adds, in the course of successive generations, more and more difference to the adult. Thus the embryo comes to be left as a sort of picture, preserved by nature, of the former and less modified condition of the species. This view may be true, and yet may never be capable of proof. Seeing, for instance, that the oldest known mammals, reptiles, and fishes strictly belong to their proper classes, though some of these old forms are in a slight degree less distinct from each other than are the typical members of the same groups at the present day, it would be vain to look for animals having the common embryological character of the Vertebrata, until beds rich in fossils are discovered far beneath the lowest Cambrian strata--a discovery of which the chance is small. ON THE SUCCESSION OF THE SAME TYPES WITHIN THE SAME AREAS, DURING THE LATER TERTIARY PERIODS. Mr. Clift many years ago showed that the fossil mammals from the Australian caves were closely allied to the living marsupials of that continent. In South America, a similar relationship is manifest, even to an uneducated eye, in the gigantic pieces of armour, like those of the armadillo, found in several parts of La Plata; and Professor Owen has shown in the most striking manner that most of the fossil mammals, buried there in such numbers, are related to South American types. This relationship is even more clearly seen in the wonderful collection of fossil bones made by MM. Lund and Clausen in the caves of Brazil. I was so much impressed with these facts that I strongly insisted, in 1839 and 1845, on this "law of the succession of types,"--on "this wonderful relationship in the same continent between the dead and the living." Professor Owen has subsequently extended the same generalisation to the mammals of the Old World. We see the same law in this author's restorations of the extinct and gigantic birds of New Zealand. We see it also in the birds of the caves of Brazil. Mr. Woodward has shown that the same law holds good with sea-shells, but, from the wide distribution of most molluscs, it is not well displayed by them. Other cases could be added, as the relation between the extinct and living land-shells of Madeira; and between the extinct and living brackish water-shells of the Aralo-Caspian Sea. Now, what does this remarkable law of the succession of the same types within the same areas mean? He would be a bold man who, after comparing the present climate of Australia and of parts of South America, under the same latitude, would attempt to account, on the one hand through dissimilar physical conditions, for the dissimilarity of the inhabitants of these two continents; and, on the other hand through similarity of conditions, for the uniformity of the same types in each continent during the later tertiary periods. Nor can it be pretended that it is an immutable law that marsupials should have been chiefly or solely produced in Australia; or that Edentata and other American types should have been solely produced in South America. For we know that Europe in ancient times was peopled by numerous marsupials; and I have shown in the publications above alluded to, that in America the law of distribution of terrestrial mammals was formerly different from what it now is. North America formerly partook strongly of the present character of the southern half of the continent; and the southern half was formerly more closely allied, than it is at present, to the northern half. In a similar manner we know, from Falconer and Cautley's discoveries, that Northern India was formerly more closely related in its mammals to Africa than it is at the present time. Analogous facts could be given in relation to the distribution of marine animals. On the theory of descent with modification, the great law of the long enduring, but not immutable, succession of the same types within the same areas, is at once explained; for the inhabitants of each quarter of the world will obviously tend to leave in that quarter, during the next succeeding period of time, closely allied though in some degree modified descendants. If the inhabitants of one continent formerly differed greatly from those of another continent, so will their modified descendants still differ in nearly the same manner and degree. But after very long intervals of time, and after great geographical changes, permitting much intermigration, the feebler will yield to the more dominant forms, and there will be nothing immutable in the distribution of organic beings. It may be asked in ridicule whether I suppose that the megatherium and other allied huge monsters, which formerly lived in South America, have left behind them the sloth, armadillo, and anteater, as their degenerate descendants. This cannot for an instant be admitted. These huge animals have become wholly extinct, and have left no progeny. But in the caves of Brazil there are many extinct species which are closely allied in size and in all other characters to the species still living in South America; and some of these fossils may have been the actual progenitors of the living species. It must not be forgotten that, on our theory, all the species of the same genus are the descendants of some one species; so that, if six genera, each having eight species, be found in one geological formation, and in a succeeding formation there be six other allied or representative genera, each with the same number of species, then we may conclude that generally only one species of each of the older genera has left modified descendants, which constitute the new genera containing the several species; the other seven species of each old genus having died out and left no progeny. Or, and this will be a far commoner case, two or three species in two or three alone of the six older genera will be the parents of the new genera: the other species and the other old genera having become utterly extinct. In failing orders, with the genera and species decreasing in numbers as is the case with the Edentata of South America, still fewer genera and species will leave modified blood-descendants. SUMMARY OF THE PRECEDING AND PRESENT CHAPTERS. I have attempted to show that the geological record is extremely imperfect; that only a small portion of the globe has been geologically explored with care; that only certain classes of organic beings have been largely preserved in a fossil state; that the number both of specimens and of species, preserved in our museums, is absolutely as nothing compared with the number of generations which must have passed away even during a single formation; that, owing to subsidence being almost necessary for the accumulation of deposits rich in fossil species of many kinds, and thick enough to outlast future degradation, great intervals of time must have elapsed between most of our successive formations; that there has probably been more extinction during the periods of subsidence, and more variation during the periods of elevation, and during the latter the record will have been least perfectly kept; that each single formation has not been continuously deposited; that the duration of each formation is probably short compared with the average duration of specific forms; that migration has played an important part in the first appearance of new forms in any one area and formation; that widely ranging species are those which have varied most frequently, and have oftenest given rise to new species; that varieties have at first been local; and lastly, although each species must have passed through numerous transitional stages, it is probable that the periods, during which each underwent modification, though many and long as measured by years, have been short in comparison with the periods during which each remained in an unchanged condition. These causes, taken conjointly, will to a large extent explain why--though we do find many links--we do not find interminable varieties, connecting together all extinct and existing forms by the finest graduated steps. It should also be constantly borne in mind that any linking variety between two forms, which might be found, would be ranked, unless the whole chain could be perfectly restored, as a new and distinct species; for it is not pretended that we have any sure criterion by which species and varieties can be discriminated. He who rejects this view of the imperfection of the geological record, will rightly reject the whole theory. For he may ask in vain where are the numberless transitional links which must formerly have connected the closely allied or representative species, found in the successive stages of the same great formation? He may disbelieve in the immense intervals of time which must have elapsed between our consecutive formations; he may overlook how important a part migration has played, when the formations of any one great region, as those of Europe, are considered; he may urge the apparent, but often falsely apparent, sudden coming in of whole groups of species. He may ask where are the remains of those infinitely numerous organisms which must have existed long before the Cambrian system was deposited? We now know that at least one animal did then exist; but I can answer this last question only by supposing that where our oceans now extend they have extended for an enormous period, and where our oscillating continents now stand they have stood since the commencement of the Cambrian system; but that, long before that epoch, the world presented a widely different aspect; and that the older continents, formed of formations older than any known to us, exist now only as remnants in a metamorphosed condition, or lie still buried under the ocean. Passing from these difficulties, the other great leading facts in palaeontology agree admirably with the theory of descent with modification through variation and natural selection. We can thus understand how it is that new species come in slowly and successively; how species of different classes do not necessarily change together, or at the same rate, or in the same degree; yet in the long run that all undergo modification to some extent. The extinction of old forms is the almost inevitable consequence of the production of new forms. We can understand why, when a species has once disappeared, it never reappears. Groups of species increase in numbers slowly, and endure for unequal periods of time; for the process of modification is necessarily slow, and depends on many complex contingencies. The dominant species belonging to large and dominant groups tend to leave many modified descendants, which form new sub-groups and groups. As these are formed, the species of the less vigorous groups, from their inferiority inherited from a common progenitor, tend to become extinct together, and to leave no modified offspring on the face of the earth. But the utter extinction of a whole group of species has sometimes been a slow process, from the survival of a few descendants, lingering in protected and isolated situations. When a group has once wholly disappeared, it does not reappear; for the link of generation has been broken. We can understand how it is that dominant forms which spread widely and yield the greatest number of varieties tend to people the world with allied, but modified, descendants; and these will generally succeed in displacing the groups which are their inferiors in the struggle for existence. Hence, after long intervals of time, the productions of the world appear to have changed simultaneously. We can understand how it is that all the forms of life, ancient and recent, make together a few grand classes. We can understand, from the continued tendency to divergence of character, why the more ancient a form is, the more it generally differs from those now living. Why ancient and extinct forms often tend to fill up gaps between existing forms, sometimes blending two groups, previously classed as distinct into one; but more commonly bringing them only a little closer together. The more ancient a form is, the more often it stands in some degree intermediate between groups now distinct; for the more ancient a form is, the more nearly it will be related to, and consequently resemble, the common progenitor of groups, since become widely divergent. Extinct forms are seldom directly intermediate between existing forms; but are intermediate only by a long and circuitous course through other extinct and different forms. We can clearly see why the organic remains of closely consecutive formations are closely allied; for they are closely linked together by generation. We can clearly see why the remains of an intermediate formation are intermediate in character. The inhabitants of the world at each successive period in its history have beaten their predecessors in the race for life, and are, in so far, higher in the scale, and their structure has generally become more specialised; and this may account for the common belief held by so many palaeontologists, that organisation on the whole has progressed. Extinct and ancient animals resemble to a certain extent the embryos of the more recent animals belonging to the same classes, and this wonderful fact receives a simple explanation according to our views. The succession of the same types of structure within the same areas during the later geological periods ceases to be mysterious, and is intelligible on the principle of inheritance. If, then, the geological record be as imperfect as many believe, and it may at least be asserted that the record cannot be proved to be much more perfect, the main objections to the theory of natural selection are greatly diminished or disappear. On the other hand, all the chief laws of palaeontology plainly proclaim, as it seems to me, that species have been produced by ordinary generation: old forms having been supplanted by new and improved forms of life, the products of variation and the survival of the fittest. CHAPTER XII. GEOGRAPHICAL DISTRIBUTION. Present distribution cannot be accounted for by differences in physical conditions--Importance of barriers--Affinity of the productions of the same continent--Centres of creation--Means of dispersal by changes of climate and of the level of the land, and by occasional means--Dispersal during the Glacial period--Alternate Glacial periods in the North and South. In considering the distribution of organic beings over the face of the globe, the first great fact which strikes us is, that neither the similarity nor the dissimilarity of the inhabitants of various regions can be wholly accounted for by climatal and other physical conditions. Of late, almost every author who has studied the subject has come to this conclusion. The case of America alone would almost suffice to prove its truth; for if we exclude the arctic and northern temperate parts, all authors agree that one of the most fundamental divisions in geographical distribution is that between the New and Old Worlds; yet if we travel over the vast American continent, from the central parts of the United States to its extreme southern point, we meet with the most diversified conditions; humid districts, arid deserts, lofty mountains, grassy plains, forests, marshes, lakes and great rivers, under almost every temperature. There is hardly a climate or condition in the Old World which cannot be paralleled in the New--at least so closely as the same species generally require. No doubt small areas can be pointed out in the Old World hotter than any in the New World; but these are not inhabited by a fauna different from that of the surrounding districts; for it is rare to find a group of organisms confined to a small area, of which the conditions are peculiar in only a slight degree. Notwithstanding this general parallelism in the conditions of Old and New Worlds, how widely different are their living productions! In the southern hemisphere, if we compare large tracts of land in Australia, South Africa, and western South America, between latitudes 25 and 35 degrees, we shall find parts extremely similar in all their conditions, yet it would not be possible to point out three faunas and floras more utterly dissimilar. Or, again, we may compare the productions of South America south of latitude 35 degrees with those north of 25 degrees, which consequently are separated by a space of ten degrees of latitude, and are exposed to considerably different conditions; yet they are incomparably more closely related to each other than they are to the productions of Australia or Africa under nearly the same climate. Analogous facts could be given with respect to the inhabitants of the sea. A second great fact which strikes us in our general review is, that barriers of any kind, or obstacles to free migration, are related in a close and important manner to the differences between the productions of various regions. We see this in the great difference in nearly all the terrestrial productions of the New and Old Worlds, excepting in the northern parts, where the land almost joins, and where, under a slightly different climate, there might have been free migration for the northern temperate forms, as there now is for the strictly arctic productions. We see the same fact in the great difference between the inhabitants of Australia, Africa, and South America under the same latitude; for these countries are almost as much isolated from each other as is possible. On each continent, also, we see the same fact; for on the opposite sides of lofty and continuous mountain-ranges, and of great deserts and even of large rivers, we find different productions; though as mountain chains, deserts, etc., are not as impassable, or likely to have endured so long, as the oceans separating continents, the differences are very inferior in degree to those characteristic of distinct continents. Turning to the sea, we find the same law. The marine inhabitants of the eastern and western shores of South America are very distinct, with extremely few shells, crustacea, or echinodermata in common; but Dr. Gunther has recently shown that about thirty per cent of the fishes are the same on the opposite sides of the isthmus of Panama; and this fact has led naturalists to believe that the isthmus was formerly open. Westward of the shores of America, a wide space of open ocean extends, with not an island as a halting-place for emigrants; here we have a barrier of another kind, and as soon as this is passed we meet in the eastern islands of the Pacific with another and totally distinct fauna. So that three marine faunas range northward and southward in parallel lines not far from each other, under corresponding climate; but from being separated from each other by impassable barriers, either of land or open sea, they are almost wholly distinct. On the other hand, proceeding still further westward from the eastern islands of the tropical parts of the Pacific, we encounter no impassable barriers, and we have innumerable islands as halting-places, or continuous coasts, until, after travelling over a hemisphere, we come to the shores of Africa; and over this vast space we meet with no well-defined and distinct marine faunas. Although so few marine animals are common to the above-named three approximate faunas of Eastern and Western America and the eastern Pacific islands, yet many fishes range from the Pacific into the Indian Ocean, and many shells are common to the eastern islands of the Pacific and the eastern shores of Africa on almost exactly opposite meridians of longitude. A third great fact, partly included in the foregoing statement, is the affinity of the productions of the same continent or of the same sea, though the species themselves are distinct at different points and stations. It is a law of the widest generality, and every continent offers innumerable instances. Nevertheless, the naturalist, in travelling, for instance, from north to south, never fails to be struck by the manner in which successive groups of beings, specifically distinct, though nearly related, replace each other. He hears from closely allied, yet distinct kinds of birds, notes nearly similar, and sees their nests similarly constructed, but not quite alike, with eggs coloured in nearly the same manner. The plains near the Straits of Magellan are inhabited by one species of Rhea (American ostrich), and northward the plains of La Plata by another species of the same genus; and not by a true ostrich or emu, like those inhabiting Africa and Australia under the same latitude. On these same plains of La Plata we see the agouti and bizcacha, animals having nearly the same habits as our hares and rabbits, and belonging to the same order of Rodents, but they plainly display an American type of structure. We ascend the lofty peaks of the Cordillera, and we find an alpine species of bizcacha; we look to the waters, and we do not find the beaver or muskrat, but the coypu and capybara, rodents of the South American type. Innumerable other instances could be given. If we look to the islands off the American shore, however much they may differ in geological structure, the inhabitants are essentially American, though they may be all peculiar species. We may look back to past ages, as shown in the last chapter, and we find American types then prevailing on the American continent and in the American seas. We see in these facts some deep organic bond, throughout space and time, over the same areas of land and water, independently of physical conditions. The naturalist must be dull who is not led to inquire what this bond is. The bond is simply inheritance, that cause which alone, as far as we positively know, produces organisms quite like each other, or, as we see in the case of varieties, nearly alike. The dissimilarity of the inhabitants of different regions may be attributed to modification through variation and natural selection, and probably in a subordinate degree to the definite influence of different physical conditions. The degrees of dissimilarity will depend on the migration of the more dominant forms of life from one region into another having been more or less effectually prevented, at periods more or less remote--on the nature and number of the former immigrants--and on the action of the inhabitants on each other in leading to the preservation of different modifications; the relation of organism to organism in the struggle for life being, as I have already often remarked, the most important of all relations. Thus the high importance of barriers comes into play by checking migration; as does time for the slow process of modification through natural selection. Widely-ranging species, abounding in individuals, which have already triumphed over many competitors in their own widely-extended homes, will have the best chance of seizing on new places, when they spread out into new countries. In their new homes they will be exposed to new conditions, and will frequently undergo further modification and improvement; and thus they will become still further victorious, and will produce groups of modified descendants. On this principle of inheritance with modification we can understand how it is that sections of genera, whole genera, and even families, are confined to the same areas, as is so commonly and notoriously the case. There is no evidence, as was remarked in the last chapter, of the existence of any law of necessary development. As the variability of each species is an independent property, and will be taken advantage of by natural selection, only so far as it profits each individual in its complex struggle for life, so the amount of modification in different species will be no uniform quantity. If a number of species, after having long competed with each other in their old home, were to migrate in a body into a new and afterwards isolated country, they would be little liable to modification; for neither migration nor isolation in themselves effect anything. These principles come into play only by bringing organisms into new relations with each other and in a lesser degree with the surrounding physical conditions. As we have seen in the last chapter that some forms have retained nearly the same character from an enormously remote geological period, so certain species have migrated over vast spaces, and have not become greatly or at all modified. According to these views, it is obvious that the several species of the same genus, though inhabiting the most distant quarters of the world, must originally have proceeded from the same source, as they are descended from the same progenitor. In the case of those species which have undergone, during whole geological periods, little modification, there is not much difficulty in believing that they have migrated from the same region; for during the vast geographical and climatical changes which have supervened since ancient times, almost any amount of migration is possible. But in many other cases, in which we have reason to believe that the species of a genus have been produced within comparatively recent times, there is great difficulty on this head. It is also obvious that the individuals of the same species, though now inhabiting distant and isolated regions, must have proceeded from one spot, where their parents were first produced: for, as has been explained, it is incredible that individuals identically the same should have been produced from parents specifically distinct. SINGLE CENTRES OF SUPPOSED CREATION. We are thus brought to the question which has been largely discussed by naturalists, namely, whether species have been created at one or more points of the earth's surface. Undoubtedly there are many cases of extreme difficulty in understanding how the same species could possibly have migrated from some one point to the several distant and isolated points, where now found. Nevertheless the simplicity of the view that each species was first produced within a single region captivates the mind. He who rejects it, rejects the vera causa of ordinary generation with subsequent migration, and calls in the agency of a miracle. It is universally admitted, that in most cases the area inhabited by a species is continuous; and that when a plant or animal inhabits two points so distant from each other, or with an interval of such a nature, that the space could not have been easily passed over by migration, the fact is given as something remarkable and exceptional. The incapacity of migrating across a wide sea is more clear in the case of terrestrial mammals than perhaps with any other organic beings; and, accordingly, we find no inexplicable instances of the same mammals inhabiting distant points of the world. No geologist feels any difficulty in Great Britain possessing the same quadrupeds with the rest of Europe, for they were no doubt once united. But if the same species can be produced at two separate points, why do we not find a single mammal common to Europe and Australia or South America? The conditions of life are nearly the same, so that a multitude of European animals and plants have become naturalised in America and Australia; and some of the aboriginal plants are identically the same at these distant points of the northern and southern hemispheres? The answer, as I believe, is, that mammals have not been able to migrate, whereas some plants, from their varied means of dispersal, have migrated across the wide and broken interspaces. The great and striking influence of barriers of all kinds, is intelligible only on the view that the great majority of species have been produced on one side, and have not been able to migrate to the opposite side. Some few families, many subfamilies, very many genera, a still greater number of sections of genera, are confined to a single region; and it has been observed by several naturalists that the most natural genera, or those genera in which the species are most closely related to each other, are generally confined to the same country, or if they have a wide range that their range is continuous. What a strange anomaly it would be if a directly opposite rule were to prevail when we go down one step lower in the series, namely to the individuals of the same species, and these had not been, at least at first, confined to some one region! Hence, it seems to me, as it has to many other naturalists, that the view of each species having been produced in one area alone, and having subsequently migrated from that area as far as its powers of migration and subsistence under past and present conditions permitted, is the most probable. Undoubtedly many cases occur in which we cannot explain how the same species could have passed from one point to the other. But the geographical and climatical changes which have certainly occurred within recent geological times, must have rendered discontinuous the formerly continuous range of many species. So that we are reduced to consider whether the exceptions to continuity of range are so numerous, and of so grave a nature, that we ought to give up the belief, rendered probable by general considerations, that each species has been produced within one area, and has migrated thence as far as it could. It would be hopelessly tedious to discuss all the exceptional cases of the same species, now living at distant and separated points; nor do I for a moment pretend that any explanation could be offered of many instances. But, after some preliminary remarks, I will discuss a few of the most striking classes of facts, namely, the existence of the same species on the summits of distant mountain ranges, and at distant points in the Arctic and Antarctic regions; and secondly (in the following chapter), the wide distribution of fresh water productions; and thirdly, the occurrence of the same terrestrial species on islands and on the nearest mainland, though separated by hundreds of miles of open sea. If the existence of the same species at distant and isolated points of the earth's surface can in many instances be explained on the view of each species having migrated from a single birthplace; then, considering our ignorance with respect to former climatical and geographical changes, and to the various occasional means of transport, the belief that a single birthplace is the law seems to me incomparably the safest. In discussing this subject we shall be enabled at the same time to consider a point equally important for us, namely, whether the several species of a genus which must on our theory all be descended from a common progenitor, can have migrated, undergoing modification during their migration from some one area. If, when most of the species inhabiting one region are different from those of another region, though closely allied to them, it can be shown that migration from the one region to the other has probably occurred at some former period, our general view will be much strengthened; for the explanation is obvious on the principle of descent with modification. A volcanic island, for instance, upheaved and formed at the distance of a few hundreds of miles from a continent, would probably receive from it in the course of time a few colonists, and their descendants, though modified, would still be related by inheritance to the inhabitants of that continent. Cases of this nature are common, and are, as we shall hereafter see, inexplicable on the theory of independent creation. This view of the relation of the species of one region to those of another, does not differ much from that advanced by Mr. Wallace, who concludes that "every species has come into existence coincident both in space and time with a pre-existing closely allied species." And it is now well known that he attributes this coincidence to descent with modification. The question of single or multiple centres of creation differs from another though allied question, namely, whether all the individuals of the same species are descended from a single pair, or single hermaphrodite, or whether, as some authors suppose, from many individuals simultaneously created. With organic beings which never intercross, if such exist, each species, must be descended from a succession of modified varieties, that have supplanted each other, but have never blended with other individuals or varieties of the same species, so that, at each successive stage of modification, all the individuals of the same form will be descended from a single parent. But in the great majority of cases, namely, with all organisms which habitually unite for each birth, or which occasionally intercross, the individuals of the same species inhabiting the same area will be kept nearly uniform by intercrossing; so that many individuals will go on simultaneously changing, and the whole amount of modification at each stage will not be due to descent from a single parent. To illustrate what I mean: our English race-horses differ from the horses of every other breed; but they do not owe their difference and superiority to descent from any single pair, but to continued care in the selecting and training of many individuals during each generation. Before discussing the three classes of facts, which I have selected as presenting the greatest amount of difficulty on the theory of "single centres of creation," I must say a few words on the means of dispersal. MEANS OF DISPERSAL. Sir C. Lyell and other authors have ably treated this subject. I can give here only the briefest abstract of the more important facts. Change of climate must have had a powerful influence on migration. A region now impassable to certain organisms from the nature of its climate, might have been a high road for migration, when the climate was different. I shall, however, presently have to discuss this branch of the subject in some detail. Changes of level in the land must also have been highly influential: a narrow isthmus now separates two marine faunas; submerge it, or let it formerly have been submerged, and the two faunas will now blend together, or may formerly have blended. Where the sea now extends, land may at a former period have connected islands or possibly even continents together, and thus have allowed terrestrial productions to pass from one to the other. No geologist disputes that great mutations of level have occurred within the period of existing organisms. Edward Forbes insisted that all the islands in the Atlantic must have been recently connected with Europe or Africa, and Europe likewise with America. Other authors have thus hypothetically bridged over every ocean, and united almost every island with some mainland. If, indeed, the arguments used by Forbes are to be trusted, it must be admitted that scarcely a single island exists which has not recently been united to some continent. This view cuts the Gordian knot of the dispersal of the same species to the most distant points, and removes many a difficulty; but to the best of my judgment we are not authorized in admitting such enormous geographical changes within the period of existing species. It seems to me that we have abundant evidence of great oscillations in the level of the land or sea; but not of such vast changes in the position and extension of our continents, as to have united them within the recent period to each other and to the several intervening oceanic islands. I freely admit the former existence of many islands, now buried beneath the sea, which may have served as halting places for plants and for many animals during their migration. In the coral-producing oceans such sunken islands are now marked by rings of coral or atolls standing over them. Whenever it is fully admitted, as it will some day be, that each species has proceeded from a single birthplace, and when in the course of time we know something definite about the means of distribution, we shall be enabled to speculate with security on the former extension of the land. But I do not believe that it will ever be proved that within the recent period most of our continents which now stand quite separate, have been continuously, or almost continuously united with each other, and with the many existing oceanic islands. Several facts in distribution--such as the great difference in the marine faunas on the opposite sides of almost every continent--the close relation of the tertiary inhabitants of several lands and even seas to their present inhabitants--the degree of affinity between the mammals inhabiting islands with those of the nearest continent, being in part determined (as we shall hereafter see) by the depth of the intervening ocean--these and other such facts are opposed to the admission of such prodigious geographical revolutions within the recent period, as are necessary on the view advanced by Forbes and admitted by his followers. The nature and relative proportions of the inhabitants of oceanic islands are likewise opposed to the belief of their former continuity of continents. Nor does the almost universally volcanic composition of such islands favour the admission that they are the wrecks of sunken continents; if they had originally existed as continental mountain ranges, some at least of the islands would have been formed, like other mountain summits, of granite, metamorphic schists, old fossiliferous and other rocks, instead of consisting of mere piles of volcanic matter. I must now say a few words on what are called accidental means, but which more properly should be called occasional means of distribution. I shall here confine myself to plants. In botanical works, this or that plant is often stated to be ill adapted for wide dissemination; but the greater or less facilities for transport across the sea may be said to be almost wholly unknown. Until I tried, with Mr. Berkeley's aid, a few experiments, it was not even known how far seeds could resist the injurious action of sea-water. To my surprise I found that out of eighty-seven kinds, sixty-four germinated after an immersion of twenty-eight days, and a few survived an immersion of 137 days. It deserves notice that certain orders were far more injured than others: nine Leguminosae were tried, and, with one exception, they resisted the salt-water badly; seven species of the allied orders, Hydrophyllaceae and Polemoniaceae, were all killed by a month's immersion. For convenience sake I chiefly tried small seeds without the capsules or fruit; and as all of these sank in a few days, they could not have been floated across wide spaces of the sea, whether or not they were injured by salt water. Afterwards I tried some larger fruits, capsules, etc., and some of these floated for a long time. It is well known what a difference there is in the buoyancy of green and seasoned timber; and it occurred to me that floods would often wash into the sea dried plants or branches with seed-capsules or fruit attached to them. Hence I was led to dry the stems and branches of ninety-four plants with ripe fruit, and to place them on sea-water. The majority sank quickly, but some which, whilst green, floated for a very short time, when dried floated much longer; for instance, ripe hazel-nuts sank immediately, but when dried they floated for ninety days, and afterwards when planted germinated; an asparagus plant with ripe berries floated for twenty-three days, when dried it floated for eighty-five days, and the seeds afterwards germinated: the ripe seeds of Helosciadium sank in two days, when dried they floated for above ninety days, and afterwards germinated. Altogether, out of the ninety-four dried plants, eighteen floated for above twenty-eight days; and some of the eighteen floated for a very much longer period. So that as 64/87 kinds of seeds germinated after an immersion of twenty-eight days; and as 18/94 distinct species with ripe fruit (but not all the same species as in the foregoing experiment) floated, after being dried, for above twenty-eight days, we may conclude, as far as anything can be inferred from these scanty facts, that the seeds of 14/100 kinds of plants of any country might be floated by sea-currents during twenty-eight days, and would retain their power of germination. In Johnston's Physical Atlas, the average rate of the several Atlantic currents is thirty-three miles per diem (some currents running at the rate of sixty miles per diem); on this average, the seeds of 14/100 plants belonging to one country might be floated across 924 miles of sea to another country; and when stranded, if blown by an inland gale to a favourable spot, would germinate. Subsequently to my experiments, M. Martens tried similar ones, but in a much better manner, for he placed the seeds in a box in the actual sea, so that they were alternately wet and exposed to the air like really floating plants. He tried ninety-eight seeds, mostly different from mine, but he chose many large fruits, and likewise seeds, from plants which live near the sea; and this would have favoured both the average length of their flotation and their resistance to the injurious action of the salt-water. On the other hand, he did not previously dry the plants or branches with the fruit; and this, as we have seen, would have caused some of them to have floated much longer. The result was that 18/98 of his seeds of different kinds floated for forty-two days, and were then capable of germination. But I do not doubt that plants exposed to the waves would float for a less time than those protected from violent movement as in our experiments. Therefore, it would perhaps be safer to assume that the seeds of about 10/100 plants of a flora, after having been dried, could be floated across a space of sea 900 miles in width, and would then germinate. The fact of the larger fruits often floating longer than the small, is interesting; as plants with large seeds or fruit which, as Alph. de Candolle has shown, generally have restricted ranges, could hardly be transported by any other means. Seeds may be occasionally transported in another manner. Drift timber is thrown up on most islands, even on those in the midst of the widest oceans; and the natives of the coral islands in the Pacific procure stones for their tools, solely from the roots of drifted trees, these stones being a valuable royal tax. I find that when irregularly shaped stones are embedded in the roots of trees, small parcels of earth are very frequently enclosed in their interstices and behind them, so perfectly that not a particle could be washed away during the longest transport: out of one small portion of earth thus COMPLETELY enclosed by the roots of an oak about fifty years old, three dicotyledonous plants germinated: I am certain of the accuracy of this observation. Again, I can show that the carcasses of birds, when floating on the sea, sometimes escape being immediately devoured; and many kinds of seeds in the crops of floating birds long retain their vitality: peas and vetches, for instance, are killed by even a few days' immersion in sea-water; but some taken out of the crop of a pigeon, which had floated on artificial sea-water for thirty days, to my surprise nearly all germinated. Living birds can hardly fail to be highly effective agents in the transportation of seeds. I could give many facts showing how frequently birds of many kinds are blown by gales to vast distances across the ocean. We may safely assume that under such circumstances their rate of flight would often be thirty-five miles an hour; and some authors have given a far higher estimate. I have never seen an instance of nutritious seeds passing through the intestines of a bird; but hard seeds of fruit pass uninjured through even the digestive organs of a turkey. In the course of two months, I picked up in my garden twelve kinds of seeds, out of the excrement of small birds, and these seemed perfect, and some of them, which were tried, germinated. But the following fact is more important: the crops of birds do not secrete gastric juice, and do not, as I know by trial, injure in the least the germination of seeds; now, after a bird has found and devoured a large supply of food, it is positively asserted that all the grains do not pass into the gizzard for twelve or even eighteen hours. A bird in this interval might easily be blown to the distance of five hundred miles, and hawks are known to look out for tired birds, and the contents of their torn crops might thus readily get scattered. Some hawks and owls bolt their prey whole, and after an interval of from twelve to twenty hours, disgorge pellets, which, as I know from experiments made in the Zoological Gardens, include seeds capable of germination. Some seeds of the oat, wheat, millet, canary, hemp, clover, and beet germinated after having been from twelve to twenty-one hours in the stomachs of different birds of prey; and two seeds of beet grew after having been thus retained for two days and fourteen hours. Fresh-water fish, I find, eat seeds of many land and water plants; fish are frequently devoured by birds, and thus the seeds might be transported from place to place. I forced many kinds of seeds into the stomachs of dead fish, and then gave their bodies to fishing-eagles, storks, and pelicans; these birds, after an interval of many hours, either rejected the seeds in pellets or passed them in their excrement; and several of these seeds retained the power of germination. Certain seeds, however, were always killed by this process. Locusts are sometimes blown to great distances from the land. I myself caught one 370 miles from the coast of Africa, and have heard of others caught at greater distances. The Rev. R.T. Lowe informed Sir C. Lyell that in November, 1844, swarms of locusts visited the island of Madeira. They were in countless numbers, as thick as the flakes of snow in the heaviest snowstorm, and extended upward as far as could be seen with a telescope. During two or three days they slowly careered round and round in an immense ellipse, at least five or six miles in diameter, and at night alighted on the taller trees, which were completely coated with them. They then disappeared over the sea, as suddenly as they had appeared, and have not since visited the island. Now, in parts of Natal it is believed by some farmers, though on insufficient evidence, that injurious seeds are introduced into their grass-land in the dung left by the great flights of locusts which often visit that country. In consequence of this belief Mr. Weale sent me in a letter a small packet of the dried pellets, out of which I extracted under the microscope several seeds, and raised from them seven grass plants, belonging to two species, of two genera. Hence a swarm of locusts, such as that which visited Madeira, might readily be the means of introducing several kinds of plants into an island lying far from the mainland. Although the beaks and feet of birds are generally clean, earth sometimes adheres to them: in one case I removed sixty-one grains, and in another case twenty-two grains of dry argillaceous earth from the foot of a partridge, and in the earth there was a pebble as large as the seed of a vetch. Here is a better case: the leg of a woodcock was sent to me by a friend, with a little cake of dry earth attached to the shank, weighing only nine grains; and this contained a seed of the toad-rush (Juncus bufonius) which germinated and flowered. Mr. Swaysland, of Brighton, who during the last forty years has paid close attention to our migratory birds, informs me that he has often shot wagtails (Motacillae), wheatears, and whinchats (Saxicolae), on their first arrival on our shores, before they had alighted; and he has several times noticed little cakes of earth attached to their feet. Many facts could be given showing how generally soil is charged with seeds. For instance, Professor Newton sent me the leg of a red-legged partridge (Caccabis rufa) which had been wounded and could not fly, with a ball of hard earth adhering to it, and weighing six and a half ounces. The earth had been kept for three years, but when broken, watered and placed under a bell glass, no less than eighty-two plants sprung from it: these consisted of twelve monocotyledons, including the common oat, and at least one kind of grass, and of seventy dicotyledons, which consisted, judging from the young leaves, of at least three distinct species. With such facts before us, can we doubt that the many birds which are annually blown by gales across great spaces of ocean, and which annually migrate--for instance, the millions of quails across the Mediterranean--must occasionally transport a few seeds embedded in dirt adhering to their feet or beaks? But I shall have to recur to this subject. As icebergs are known to be sometimes loaded with earth and stones, and have even carried brushwood, bones, and the nest of a land-bird, it can hardly be doubted that they must occasionally, as suggested by Lyell, have transported seeds from one part to another of the arctic and antarctic regions; and during the Glacial period from one part of the now temperate regions to another. In the Azores, from the large number of plants common to Europe, in comparison with the species on the other islands of the Atlantic, which stand nearer to the mainland, and (as remarked by Mr. H.C. Watson) from their somewhat northern character, in comparison with the latitude, I suspected that these islands had been partly stocked by ice-borne seeds during the Glacial epoch. At my request Sir C. Lyell wrote to M. Hartung to inquire whether he had observed erratic boulders on these islands, and he answered that he had found large fragments of granite and other rocks, which do not occur in the archipelago. Hence we may safely infer that icebergs formerly landed their rocky burdens on the shores of these mid-ocean islands, and it is at least possible that they may have brought thither the seeds of northern plants. Considering that these several means of transport, and that other means, which without doubt remain to be discovered, have been in action year after year for tens of thousands of years, it would, I think, be a marvellous fact if many plants had not thus become widely transported. These means of transport are sometimes called accidental, but this is not strictly correct: the currents of the sea are not accidental, nor is the direction of prevalent gales of wind. It should be observed that scarcely any means of transport would carry seeds for very great distances; for seeds do not retain their vitality when exposed for a great length of time to the action of sea water; nor could they be long carried in the crops or intestines of birds. These means, however, would suffice for occasional transport across tracts of sea some hundred miles in breadth, or from island to island, or from a continent to a neighbouring island, but not from one distant continent to another. The floras of distant continents would not by such means become mingled; but would remain as distinct as they now are. The currents, from their course, would never bring seeds from North America to Britain, though they might and do bring seeds from the West Indies to our western shores, where, if not killed by their very long immersion in salt water, they could not endure our climate. Almost every year, one or two land-birds are blown across the whole Atlantic Ocean, from North America to the western shores of Ireland and England; but seeds could be transported by these rare wanderers only by one means, namely, by dirt adhering to their feet or beaks, which is in itself a rare accident. Even in this case, how small would be the chance of a seed falling on favourable soil, and coming to maturity! But it would be a great error to argue that because a well-stocked island, like Great Britain, has not, as far as is known (and it would be very difficult to prove this), received within the last few centuries, through occasional means of transport, immigrants from Europe or any other continent, that a poorly-stocked island, though standing more remote from the mainland, would not receive colonists by similar means. Out of a hundred kinds of seeds or animals transported to an island, even if far less well-stocked than Britain, perhaps not more than one would be so well fitted to its new home, as to become naturalised. But this is no valid argument against what would be effected by occasional means of transport, during the long lapse of geological time, whilst the island was being upheaved, and before it had become fully stocked with inhabitants. On almost bare land, with few or no destructive insects or birds living there, nearly every seed which chanced to arrive, if fitted for the climate, would germinate and survive. DISPERSAL DURING THE GLACIAL PERIOD. The identity of many plants and animals, on mountain-summits, separated from each other by hundreds of miles of lowlands, where Alpine species could not possibly exist, is one of the most striking cases known of the same species living at distant points, without the apparent possibility of their having migrated from one point to the other. It is indeed a remarkable fact to see so many plants of the same species living on the snowy regions of the Alps or Pyrenees, and in the extreme northern parts of Europe; but it is far more remarkable, that the plants on the White Mountains, in the United States of America, are all the same with those of Labrador, and nearly all the same, as we hear from Asa Gray, with those on the loftiest mountains of Europe. Even as long ago as 1747, such facts led Gmelin to conclude that the same species must have been independently created at many distinct points; and we might have remained in this same belief, had not Agassiz and others called vivid attention to the Glacial period, which, as we shall immediately see, affords a simple explanation of these facts. We have evidence of almost every conceivable kind, organic and inorganic, that, within a very recent geological period, central Europe and North America suffered under an Arctic climate. The ruins of a house burnt by fire do not tell their tale more plainly than do the mountains of Scotland and Wales, with their scored flanks, polished surfaces, and perched boulders, of the icy streams with which their valleys were lately filled. So greatly has the climate of Europe changed, that in Northern Italy, gigantic moraines, left by old glaciers, are now clothed by the vine and maize. Throughout a large part of the United States, erratic boulders and scored rocks plainly reveal a former cold period. The former influence of the glacial climate on the distribution of the inhabitants of Europe, as explained by Edward Forbes, is substantially as follows. But we shall follow the changes more readily, by supposing a new glacial period slowly to come on, and then pass away, as formerly occurred. As the cold came on, and as each more southern zone became fitted for the inhabitants of the north, these would take the places of the former inhabitants of the temperate regions. The latter, at the same time would travel further and further southward, unless they were stopped by barriers, in which case they would perish. The mountains would become covered with snow and ice, and their former Alpine inhabitants would descend to the plains. By the time that the cold had reached its maximum, we should have an arctic fauna and flora, covering the central parts of Europe, as far south as the Alps and Pyrenees, and even stretching into Spain. The now temperate regions of the United States would likewise be covered by arctic plants and animals and these would be nearly the same with those of Europe; for the present circumpolar inhabitants, which we suppose to have everywhere travelled southward, are remarkably uniform round the world. As the warmth returned, the arctic forms would retreat northward, closely followed up in their retreat by the productions of the more temperate regions. And as the snow melted from the bases of the mountains, the arctic forms would seize on the cleared and thawed ground, always ascending, as the warmth increased and the snow still further disappeared, higher and higher, whilst their brethren were pursuing their northern journey. Hence, when the warmth had fully returned, the same species, which had lately lived together on the European and North American lowlands, would again be found in the arctic regions of the Old and New Worlds, and on many isolated mountain-summits far distant from each other. Thus we can understand the identity of many plants at points so immensely remote as the mountains of the United States and those of Europe. We can thus also understand the fact that the Alpine plants of each mountain-range are more especially related to the arctic forms living due north or nearly due north of them: for the first migration when the cold came on, and the re-migration on the returning warmth, would generally have been due south and north. The Alpine plants, for example, of Scotland, as remarked by Mr. H.C. Watson, and those of the Pyrenees, as remarked by Ramond, are more especially allied to the plants of northern Scandinavia; those of the United States to Labrador; those of the mountains of Siberia to the arctic regions of that country. These views, grounded as they are on the perfectly well-ascertained occurrence of a former Glacial period, seem to me to explain in so satisfactory a manner the present distribution of the Alpine and Arctic productions of Europe and America, that when in other regions we find the same species on distant mountain-summits, we may almost conclude, without other evidence, that a colder climate formerly permitted their migration across the intervening lowlands, now become too warm for their existence. As the arctic forms moved first southward and afterwards backward to the north, in unison with the changing climate, they will not have been exposed during their long migrations to any great diversity of temperature; and as they all migrated in a body together, their mutual relations will not have been much disturbed. Hence, in accordance with the principles inculcated in this volume, these forms will not have been liable to much modification. But with the Alpine productions, left isolated from the moment of the returning warmth, first at the bases and ultimately on the summits of the mountains, the case will have been somewhat different; for it is not likely that all the same arctic species will have been left on mountain ranges far distant from each other, and have survived there ever since; they will also, in all probability, have become mingled with ancient Alpine species, which must have existed on the mountains before the commencement of the Glacial epoch, and which during the coldest period will have been temporarily driven down to the plains; they will, also, have been subsequently exposed to somewhat different climatical influences. Their mutual relations will thus have been in some degree disturbed; consequently they will have been liable to modification; and they have been modified; for if we compare the present Alpine plants and animals of the several great European mountain ranges, one with another, though many of the species remain identically the same, some exist as varieties, some as doubtful forms or sub-species and some as distinct yet closely allied species representing each other on the several ranges. In the foregoing illustration, I have assumed that at the commencement of our imaginary Glacial period, the arctic productions were as uniform round the polar regions as they are at the present day. But it is also necessary to assume that many sub-arctic and some few temperate forms were the same round the world, for some of the species which now exist on the lower mountain slopes and on the plains of North America and Europe are the same; and it may be asked how I account for this degree of uniformity of the sub-arctic and temperate forms round the world, at the commencement of the real Glacial period. At the present day, the sub-arctic and northern temperate productions of the Old and New Worlds are separated from each other by the whole Atlantic Ocean and by the northern part of the Pacific. During the Glacial period, when the inhabitants of the Old and New Worlds lived further southwards than they do at present, they must have been still more completely separated from each other by wider spaces of ocean; so that it may well be asked how the same species could then or previously have entered the two continents. The explanation, I believe, lies in the nature of the climate before the commencement of the Glacial period. At this, the newer Pliocene period, the majority of the inhabitants of the world were specifically the same as now, and we have good reason to believe that the climate was warmer than at the present day. Hence, we may suppose that the organisms which now live under latitude 60 degrees, lived during the Pliocene period further north, under the Polar Circle, in latitude 66-67 degrees; and that the present arctic productions then lived on the broken land still nearer to the pole. Now, if we look at a terrestrial globe, we see under the Polar Circle that there is almost continuous land from western Europe through Siberia, to eastern America. And this continuity of the circumpolar land, with the consequent freedom under a more favourable climate for intermigration, will account for the supposed uniformity of the sub-arctic and temperate productions of the Old and New Worlds, at a period anterior to the Glacial epoch. Believing, from reasons before alluded to, that our continents have long remained in nearly the same relative position, though subjected to great oscillations of level, I am strongly inclined to extend the above view, and to infer that during some earlier and still warmer period, such as the older Pliocene period, a large number of the same plants and animals inhabited the almost continuous circumpolar land; and that these plants and animals, both in the Old and New Worlds, began slowly to migrate southwards as the climate became less warm, long before the commencement of the Glacial period. We now see, as I believe, their descendants, mostly in a modified condition, in the central parts of Europe and the United States. On this view we can understand the relationship with very little identity, between the productions of North America and Europe--a relationship which is highly remarkable, considering the distance of the two areas, and their separation by the whole Atlantic Ocean. We can further understand the singular fact remarked on by several observers that the productions of Europe and America during the later tertiary stages were more closely related to each other than they are at the present time; for during these warmer periods the northern parts of the Old and New Worlds will have been almost continuously united by land, serving as a bridge, since rendered impassable by cold, for the intermigration of their inhabitants. During the slowly decreasing warmth of the Pliocene period, as soon as the species in common, which inhabited the New and Old Worlds, migrated south of the Polar Circle, they will have been completely cut off from each other. This separation, as far as the more temperate productions are concerned, must have taken place long ages ago. As the plants and animals migrated southward, they will have become mingled in the one great region with the native American productions, and would have had to compete with them; and in the other great region, with those of the Old World. Consequently we have here everything favourable for much modification--for far more modification than with the Alpine productions, left isolated, within a much more recent period, on the several mountain ranges and on the arctic lands of Europe and North America. Hence, it has come, that when we compare the now living productions of the temperate regions of the New and Old Worlds, we find very few identical species (though Asa Gray has lately shown that more plants are identical than was formerly supposed), but we find in every great class many forms, which some naturalists rank as geographical races, and others as distinct species; and a host of closely allied or representative forms which are ranked by all naturalists as specifically distinct. As on the land, so in the waters of the sea, a slow southern migration of a marine fauna, which, during the Pliocene or even a somewhat earlier period, was nearly uniform along the continuous shores of the Polar Circle, will account, on the theory of modification, for many closely allied forms now living in marine areas completely sundered. Thus, I think, we can understand the presence of some closely allied, still existing and extinct tertiary forms, on the eastern and western shores of temperate North America; and the still more striking fact of many closely allied crustaceans (as described in Dana's admirable work), some fish and other marine animals, inhabiting the Mediterranean and the seas of Japan--these two areas being now completely separated by the breadth of a whole continent and by wide spaces of ocean. These cases of close relationship in species either now or formerly inhabiting the seas on the eastern and western shores of North America, the Mediterranean and Japan, and the temperate lands of North America and Europe, are inexplicable on the theory of creation. We cannot maintain that such species have been created alike, in correspondence with the nearly similar physical conditions of the areas; for if we compare, for instance, certain parts of South America with parts of South Africa or Australia, we see countries closely similar in all their physical conditions, with their inhabitants utterly dissimilar. ALTERNATE GLACIAL PERIODS IN THE NORTH AND SOUTH. But we must return to our more immediate subject. I am convinced that Forbes's view may be largely extended. In Europe we meet with the plainest evidence of the Glacial period, from the western shores of Britain to the Ural range, and southward to the Pyrenees. We may infer from the frozen mammals and nature of the mountain vegetation, that Siberia was similarly affected. In the Lebanon, according to Dr. Hooker, perpetual snow formerly covered the central axis, and fed glaciers which rolled 4,000 feet down the valleys. The same observer has recently found great moraines at a low level on the Atlas range in North Africa. Along the Himalaya, at points 900 miles apart, glaciers have left the marks of their former low descent; and in Sikkim, Dr. Hooker saw maize growing on ancient and gigantic moraines. Southward of the Asiatic continent, on the opposite side of the equator, we know, from the excellent researches of Dr. J. Haast and Dr. Hector, that in New Zealand immense glaciers formerly descended to a low level; and the same plants, found by Dr. Hooker on widely separated mountains in this island tell the same story of a former cold period. From facts communicated to me by the Rev. W.B. Clarke, it appears also that there are traces of former glacial action on the mountains of the south-eastern corner of Australia. Looking to America: in the northern half, ice-borne fragments of rock have been observed on the eastern side of the continent, as far south as latitude 36 and 37 degrees, and on the shores of the Pacific, where the climate is now so different, as far south as latitude 46 degrees. Erratic boulders have, also, been noticed on the Rocky Mountains. In the Cordillera of South America, nearly under the equator, glaciers once extended far below their present level. In central Chile I examined a vast mound of detritus with great boulders, crossing the Portillo valley, which, there can hardly be a doubt, once formed a huge moraine; and Mr. D. Forbes informs me that he found in various parts of the Cordillera, from latitude 13 to 30 degrees south, at about the height of 12,000 feet, deeply-furrowed rocks, resembling those with which he was familiar in Norway, and likewise great masses of detritus, including grooved pebbles. Along this whole space of the Cordillera true glaciers do not now exist even at much more considerable heights. Further south, on both sides of the continent, from latitude 41 degrees to the southernmost extremity, we have the clearest evidence of former glacial action, in numerous immense boulders transported far from their parent source. From these several facts, namely, from the glacial action having extended all round the northern and southern hemispheres--from the period having been in a geological sense recent in both hemispheres--from its having lasted in both during a great length of time, as may be inferred from the amount of work effected--and lastly, from glaciers having recently descended to a low level along the whole line of the Cordillera, it at one time appeared to me that we could not avoid the conclusion that the temperature of the whole world had been simultaneously lowered during the Glacial period. But now, Mr. Croll, in a series of admirable memoirs, has attempted to show that a glacial condition of climate is the result of various physical causes, brought into operation by an increase in the eccentricity of the earth's orbit. All these causes tend towards the same end; but the most powerful appears to be the indirect influence of the eccentricity of the orbit upon oceanic currents. According to Mr. Croll, cold periods regularly recur every ten or fifteen thousand years; and these at long intervals are extremely severe, owing to certain contingencies, of which the most important, as Sir C. Lyell has shown, is the relative position of the land and water. Mr. Croll believes that the last great glacial period occurred about 240,000 years ago, and endured, with slight alterations of climate, for about 160,000 years. With respect to more ancient glacial periods, several geologists are convinced, from direct evidence, that such occurred during the miocene and eocene formations, not to mention still more ancient formations. But the most important result for us, arrived at by Mr. Croll, is that whenever the northern hemisphere passes through a cold period the temperature of the southern hemisphere is actually raised, with the winters rendered much milder, chiefly through changes in the direction of the ocean currents. So conversely it will be with the northern hemisphere, while the southern passes through a glacial period. This conclusion throws so much light on geographical distribution that I am strongly inclined to trust in it; but I will first give the facts which demand an explanation. In South America, Dr. Hooker has shown that besides many closely allied species, between forty and fifty of the flowering plants of Tierra del Fuego, forming no inconsiderable part of its scanty flora, are common to North America and Europe, enormously remote as these areas in opposite hemispheres are from each other. On the lofty mountains of equatorial America a host of peculiar species belonging to European genera occur. On the Organ Mountains of Brazil some few temperate European, some Antarctic and some Andean genera were found by Gardner which do not exist in the low intervening hot countries. On the Silla of Caraccas the illustrious Humboldt long ago found species belonging to genera characteristic of the Cordillera. In Africa, several forms characteristic of Europe, and some few representatives of the flora of the Cape of Good Hope, occur on the mountains of Abyssinia. At the Cape of Good Hope a very few European species, believed not to have been introduced by man, and on the mountains several representative European forms are found which have not been discovered in the intertropical parts of Africa. Dr. Hooker has also lately shown that several of the plants living on the upper parts of the lofty island of Fernando Po, and on the neighbouring Cameroon Mountains, in the Gulf of Guinea, are closely related to those on the mountains of Abyssinia, and likewise to those of temperate Europe. It now also appears, as I hear from Dr. Hooker, that some of these same temperate plants have been discovered by the Rev. R.T. Lowe on the mountains of the Cape Verde Islands. This extension of the same temperate forms, almost under the equator, across the whole continent of Africa and to the mountains of the Cape Verde archipelago, is one of the most astonishing facts ever recorded in the distribution of plants. On the Himalaya, and on the isolated mountain ranges of the peninsula of India, on the heights of Ceylon, and on the volcanic cones of Java, many plants occur either identically the same or representing each other, and at the same time representing plants of Europe not found in the intervening hot lowlands. A list of the genera of plants collected on the loftier peaks of Java, raises a picture of a collection made on a hillock in Europe. Still more striking is the fact that peculiar Australian forms are represented by certain plants growing on the summits of the mountains of Borneo. Some of these Australian forms, as I hear from Dr. Hooker, extend along the heights of the peninsula of Malacca, and are thinly scattered on the one hand over India, and on the other hand as far north as Japan. On the southern mountains of Australia, Dr. F. Muller has discovered several European species; other species, not introduced by man, occur on the lowlands; and a long list can be given, as I am informed by Dr. Hooker, of European genera, found in Australia, but not in the intermediate torrid regions. In the admirable "Introduction to the Flora of New Zealand," by Dr. Hooker, analogous and striking facts are given in regard to the plants of that large island. Hence, we see that certain plants growing on the more lofty mountains of the tropics in all parts of the world, and on the temperate plains of the north and south, are either the same species or varieties of the same species. It should, however, be observed that these plants are not strictly arctic forms; for, as Mr. H.C. Watson has remarked, "in receding from polar toward equatorial latitudes, the Alpine or mountain flora really become less and less Arctic." Besides these identical and closely allied forms, many species inhabiting the same widely sundered areas, belong to genera not now found in the intermediate tropical lowlands. These brief remarks apply to plants alone; but some few analogous facts could be given in regard to terrestrial animals. In marine productions, similar cases likewise occur; as an example, I may quote a statement by the highest authority, Prof. Dana, that "it is certainly a wonderful fact that New Zealand should have a closer resemblance in its crustacea to Great Britain, its antipode, than to any other part of the world." Sir J. Richardson, also, speaks of the reappearance on the shores of New Zealand, Tasmania, etc., of northern forms of fish. Dr. Hooker informs me that twenty-five species of Algae are common to New Zealand and to Europe, but have not been found in the intermediate tropical seas. From the foregoing facts, namely, the presence of temperate forms on the highlands across the whole of equatorial Africa, and along the Peninsula of India, to Ceylon and the Malay Archipelago, and in a less well-marked manner across the wide expanse of tropical South America, it appears almost certain that at some former period, no doubt during the most severe part of a Glacial period, the lowlands of these great continents were everywhere tenanted under the equator by a considerable number of temperate forms. At this period the equatorial climate at the level of the sea was probably about the same with that now experienced at the height of from five to six thousand feet under the same latitude, or perhaps even rather cooler. During this, the coldest period, the lowlands under the equator must have been clothed with a mingled tropical and temperate vegetation, like that described by Hooker as growing luxuriantly at the height of from four to five thousand feet on the lower slopes of the Himalaya, but with perhaps a still greater preponderance of temperate forms. So again in the mountainous island of Fernando Po, in the Gulf of Guinea, Mr. Mann found temperate European forms beginning to appear at the height of about five thousand feet. On the mountains of Panama, at the height of only two thousand feet, Dr. Seemann found the vegetation like that of Mexico, "with forms of the torrid zone harmoniously blended with those of the temperate." Now let us see whether Mr. Croll's conclusion that when the northern hemisphere suffered from the extreme cold of the great Glacial period, the southern hemisphere was actually warmer, throws any clear light on the present apparently inexplicable distribution of various organisms in the temperate parts of both hemispheres, and on the mountains of the tropics. The Glacial period, as measured by years, must have been very long; and when we remember over what vast spaces some naturalised plants and animals have spread within a few centuries, this period will have been ample for any amount of migration. As the cold became more and more intense, we know that Arctic forms invaded the temperate regions; and from the facts just given, there can hardly be a doubt that some of the more vigorous, dominant and widest-spreading temperate forms invaded the equatorial lowlands. The inhabitants of these hot lowlands would at the same time have migrated to the tropical and subtropical regions of the south, for the southern hemisphere was at this period warmer. On the decline of the Glacial period, as both hemispheres gradually recovered their former temperature, the northern temperate forms living on the lowlands under the equator, would have been driven to their former homes or have been destroyed, being replaced by the equatorial forms returning from the south. Some, however, of the northern temperate forms would almost certainly have ascended any adjoining high land, where, if sufficiently lofty, they would have long survived like the Arctic forms on the mountains of Europe. They might have survived, even if the climate was not perfectly fitted for them, for the change of temperature must have been very slow, and plants undoubtedly possess a certain capacity for acclimatisation, as shown by their transmitting to their offspring different constitutional powers of resisting heat and cold. In the regular course of events the southern hemisphere would in its turn be subjected to a severe Glacial period, with the northern hemisphere rendered warmer; and then the southern temperate forms would invade the equatorial lowlands. The northern forms which had before been left on the mountains would now descend and mingle with the southern forms. These latter, when the warmth returned, would return to their former homes, leaving some few species on the mountains, and carrying southward with them some of the northern temperate forms which had descended from their mountain fastnesses. Thus, we should have some few species identically the same in the northern and southern temperate zones and on the mountains of the intermediate tropical regions. But the species left during a long time on these mountains, or in opposite hemispheres, would have to compete with many new forms and would be exposed to somewhat different physical conditions; hence, they would be eminently liable to modification, and would generally now exist as varieties or as representative species; and this is the case. We must, also, bear in mind the occurrence in both hemispheres of former Glacial periods; for these will account, in accordance with the same principles, for the many quite distinct species inhabiting the same widely separated areas, and belonging to genera not now found in the intermediate torrid zones. It is a remarkable fact, strongly insisted on by Hooker in regard to America, and by Alph. de Candolle in regard to Australia, that many more identical or slightly modified species have migrated from the north to the south, than in a reversed direction. We see, however, a few southern forms on the mountains of Borneo and Abyssinia. I suspect that this preponderant migration from the north to the south is due to the greater extent of land in the north, and to the northern forms having existed in their own homes in greater numbers, and having consequently been advanced through natural selection and competition to a higher stage of perfection, or dominating power, than the southern forms. And thus, when the two sets became commingled in the equatorial regions, during the alternations of the Glacial periods, the northern forms were the more powerful and were able to hold their places on the mountains, and afterwards migrate southward with the southern forms; but not so the southern in regard to the northern forms. In the same manner, at the present day, we see that very many European productions cover the ground in La Plata, New Zealand, and to a lesser degree in Australia, and have beaten the natives; whereas extremely few southern forms have become naturalised in any part of the northern hemisphere, though hides, wool, and other objects likely to carry seeds have been largely imported into Europe during the last two or three centuries from La Plata and during the last forty or fifty years from Australia. The Neilgherrie Mountains in India, however, offer a partial exception; for here, as I hear from Dr. Hooker, Australian forms are rapidly sowing themselves and becoming naturalised. Before the last great Glacial period, no doubt the intertropical mountains were stocked with endemic Alpine forms; but these have almost everywhere yielded to the more dominant forms generated in the larger areas and more efficient workshops of the north. In many islands the native productions are nearly equalled, or even outnumbered, by those which have become naturalised; and this is the first stage towards their extinction. Mountains are islands on the land; and their inhabitants have yielded to those produced within the larger areas of the north, just in the same way as the inhabitants of real islands have everywhere yielded and are still yielding to continental forms naturalised through man's agency. The same principles apply to the distribution of terrestrial animals and of marine productions, in the northern and southern temperate zones, and on the intertropical mountains. When, during the height of the Glacial period, the ocean-currents were widely different to what they now are, some of the inhabitants of the temperate seas might have reached the equator; of these a few would perhaps at once be able to migrate southwards, by keeping to the cooler currents, while others might remain and survive in the colder depths until the southern hemisphere was in its turn subjected to a glacial climate and permitted their further progress; in nearly the same manner as, according to Forbes, isolated spaces inhabited by Arctic productions exist to the present day in the deeper parts of the northern temperate seas. I am far from supposing that all the difficulties in regard to the distribution and affinities of the identical and allied species, which now live so widely separated in the north and south, and sometimes on the intermediate mountain ranges, are removed on the views above given. The exact lines of migration cannot be indicated. We cannot say why certain species and not others have migrated; why certain species have been modified and have given rise to new forms, while others have remained unaltered. We cannot hope to explain such facts, until we can say why one species and not another becomes naturalised by man's agency in a foreign land; why one species ranges twice or thrice as far, and is twice or thrice as common, as another species within their own homes. Various special difficulties also remain to be solved; for instance, the occurrence, as shown by Dr. Hooker, of the same plants at points so enormously remote as Kerguelen Land, New Zealand, and Fuegia; but icebergs, as suggested by Lyell, may have been concerned in their dispersal. The existence at these and other distant points of the southern hemisphere, of species, which, though distinct, belong to genera exclusively confined to the south, is a more remarkable case. Some of these species are so distinct, that we cannot suppose that there has been time since the commencement of the last Glacial period for their migration and subsequent modification to the necessary degree. The facts seem to indicate that distinct species belonging to the same genera have migrated in radiating lines from a common centre; and I am inclined to look in the southern, as in the northern hemisphere, to a former and warmer period, before the commencement of the last Glacial period, when the Antarctic lands, now covered with ice, supported a highly peculiar and isolated flora. It may be suspected that before this flora was exterminated during the last Glacial epoch, a few forms had been already widely dispersed to various points of the southern hemisphere by occasional means of transport, and by the aid, as halting-places, of now sunken islands. Thus the southern shores of America, Australia, and New Zealand may have become slightly tinted by the same peculiar forms of life. Sir C. Lyell in a striking passage has speculated, in language almost identical with mine, on the effects of great alternations of climate throughout the world on geographical distribution. And we have now seen that Mr. Croll's conclusion that successive Glacial periods in the one hemisphere coincide with warmer periods in the opposite hemisphere, together with the admission of the slow modification of species, explains a multitude of facts in the distribution of the same and of the allied forms of life in all parts of the globe. The living waters have flowed during one period from the north and during another from the south, and in both cases have reached the equator; but the stream of life has flowed with greater force from the north than in the opposite direction, and has consequently more freely inundated the south. As the tide leaves its drift in horizontal lines, rising higher on the shores where the tide rises highest, so have the living waters left their living drift on our mountain summits, in a line gently rising from the Arctic lowlands to a great latitude under the equator. The various beings thus left stranded may be compared with savage races of man, driven up and surviving in the mountain fastnesses of almost every land, which serves as a record, full of interest to us, of the former inhabitants of the surrounding lowlands. CHAPTER XIII. GEOGRAPHICAL DISTRIBUTION--continued. Distribution of fresh-water productions--On the inhabitants of oceanic islands--Absence of Batrachians and of terrestrial Mammals--On the relation of the inhabitants of islands to those of the nearest mainland--On colonisation from the nearest source with subsequent modification--Summary of the last and present chapters. FRESH-WATER PRODUCTIONS. As lakes and river-systems are separated from each other by barriers of land, it might have been thought that fresh-water productions would not have ranged widely within the same country, and as the sea is apparently a still more formidable barrier, that they would never have extended to distant countries. But the case is exactly the reverse. Not only have many fresh-water species, belonging to different classes, an enormous range, but allied species prevail in a remarkable manner throughout the world. When first collecting in the fresh waters of Brazil, I well remember feeling much surprise at the similarity of the fresh-water insects, shells, etc., and at the dissimilarity of the surrounding terrestrial beings, compared with those of Britain. But the wide ranging power of fresh-water productions can, I think, in most cases be explained by their having become fitted, in a manner highly useful to them, for short and frequent migrations from pond to pond, or from stream to stream, within their own countries; and liability to wide dispersal would follow from this capacity as an almost necessary consequence. We can here consider only a few cases; of these, some of the most difficult to explain are presented by fish. It was formerly believed that the same fresh-water species never existed on two continents distant from each other. But Dr. Gunther has lately shown that the Galaxias attenuatus inhabits Tasmania, New Zealand, the Falkland Islands and the mainland of South America. This is a wonderful case, and probably indicates dispersal from an Antarctic centre during a former warm period. This case, however, is rendered in some degree less surprising by the species of this genus having the power of crossing by some unknown means considerable spaces of open ocean: thus there is one species common to New Zealand and to the Auckland Islands, though separated by a distance of about 230 miles. On the same continent fresh-water fish often range widely, and as if capriciously; for in two adjoining river systems some of the species may be the same and some wholly different. It is probable that they are occasionally transported by what may be called accidental means. Thus fishes still alive are not very rarely dropped at distant points by whirlwinds; and it is known that the ova retain their vitality for a considerable time after removal from the water. Their dispersal may, however, be mainly attributed to changes in the level of the land within the recent period, causing rivers to flow into each other. Instances, also, could be given of this having occurred during floods, without any change of level. The wide differences of the fish on the opposite sides of most mountain-ranges, which are continuous and consequently must, from an early period, have completely prevented the inosculation of the river systems on the two sides, leads to the same conclusion. Some fresh-water fish belong to very ancient forms, and in such cases there will have been ample time for great geographical changes, and consequently time and means for much migration. Moreover, Dr. Gunther has recently been led by several considerations to infer that with fishes the same forms have a long endurance. Salt-water fish can with care be slowly accustomed to live in fresh water; and, according to Valenciennes, there is hardly a single group of which all the members are confined to fresh water, so that a marine species belonging to a fresh-water group might travel far along the shores of the sea, and could, it is probable, become adapted without much difficulty to the fresh waters of a distant land. Some species of fresh-water shells have very wide ranges, and allied species which, on our theory, are descended from a common parent, and must have proceeded from a single source, prevail throughout the world. Their distribution at first perplexed me much, as their ova are not likely to be transported by birds; and the ova, as well as the adults, are immediately killed by sea-water. I could not even understand how some naturalised species have spread rapidly throughout the same country. But two facts, which I have observed--and many others no doubt will be discovered--throw some light on this subject. When ducks suddenly emerge from a pond covered with duck-weed, I have twice seen these little plants adhering to their backs; and it has happened to me, in removing a little duck-weed from one aquarium to another, that I have unintentionally stocked the one with fresh-water shells from the other. But another agency is perhaps more effectual: I suspended the feet of a duck in an aquarium, where many ova of fresh-water shells were hatching; and I found that numbers of the extremely minute and just-hatched shells crawled on the feet, and clung to them so firmly that when taken out of the water they could not be jarred off, though at a somewhat more advanced age they would voluntarily drop off. These just-hatched molluscs, though aquatic in their nature, survived on the duck's feet, in damp air, from twelve to twenty hours; and in this length of time a duck or heron might fly at least six or seven hundred miles, and if blown across the sea to an oceanic island, or to any other distant point, would be sure to alight on a pool or rivulet. Sir Charles Lyell informs me that a Dyticus has been caught with an Ancylus (a fresh-water shell like a limpet) firmly adhering to it; and a water-beetle of the same family, a Colymbetes, once flew on board the "Beagle," when forty-five miles distant from the nearest land: how much farther it might have been blown by a favouring gale no one can tell. With respect to plants, it has long been known what enormous ranges many fresh-water, and even marsh-species, have, both over continents and to the most remote oceanic islands. This is strikingly illustrated, according to Alph. de Candolle, in those large groups of terrestrial plants, which have very few aquatic members; for the latter seem immediately to acquire, as if in consequence, a wide range. I think favourable means of dispersal explain this fact. I have before mentioned that earth occasionally adheres in some quantity to the feet and beaks of birds. Wading birds, which frequent the muddy edges of ponds, if suddenly flushed, would be the most likely to have muddy feet. Birds of this order wander more than those of any other; and are occasionally found on the most remote and barren islands of the open ocean; they would not be likely to alight on the surface of the sea, so that any dirt on their feet would not be washed off; and when gaining the land, they would be sure to fly to their natural fresh-water haunts. I do not believe that botanists are aware how charged the mud of ponds is with seeds: I have tried several little experiments, but will here give only the most striking case: I took in February three tablespoonfuls of mud from three different points, beneath water, on the edge of a little pond; this mud when dry weighed only 6 and 3/4 ounces; I kept it covered up in my study for six months, pulling up and counting each plant as it grew; the plants were of many kinds, and were altogether 537 in number; and yet the viscid mud was all contained in a breakfast cup! Considering these facts, I think it would be an inexplicable circumstance if water-birds did not transport the seeds of fresh-water plants to unstocked ponds and streams, situated at very distant points. The same agency may have come into play with the eggs of some of the smaller fresh-water animals. Other and unknown agencies probably have also played a part. I have stated that fresh-water fish eat some kinds of seeds, though they reject many other kinds after having swallowed them; even small fish swallow seeds of moderate size, as of the yellow water-lily and Potamogeton. Herons and other birds, century after century, have gone on daily devouring fish; they then take flight and go to other waters, or are blown across the sea; and we have seen that seeds retain their power of germination, when rejected many hours afterwards in pellets or in the excrement. When I saw the great size of the seeds of that fine water-lily, the Nelumbium, and remembered Alph. de Candolle's remarks on the distribution of this plant, I thought that the means of its dispersal must remain inexplicable; but Audubon states that he found the seeds of the great southern water-lily (probably according to Dr. Hooker, the Nelumbium luteum) in a heron's stomach. Now this bird must often have flown with its stomach thus well stocked to distant ponds, and, then getting a hearty meal of fish, analogy makes me believe that it would have rejected the seeds in the pellet in a fit state for germination. In considering these several means of distribution, it should be remembered that when a pond or stream is first formed, for instance on a rising islet, it will be unoccupied; and a single seed or egg will have a good chance of succeeding. Although there will always be a struggle for life between the inhabitants of the same pond, however few in kind, yet as the number even in a well-stocked pond is small in comparison with the number of species inhabiting an equal area of land, the competition between them will probably be less severe than between terrestrial species; consequently an intruder from the waters of a foreign country would have a better chance of seizing on a new place, than in the case of terrestrial colonists. We should also remember that many fresh-water productions are low in the scale of nature, and we have reason to believe that such beings become modified more slowly than the high; and this will give time for the migration of aquatic species. We should not forget the probability of many fresh-water forms having formerly ranged continuously over immense areas, and then having become extinct at intermediate points. But the wide distribution of fresh-water plants, and of the lower animals, whether retaining the same identical form, or in some degree modified, apparently depends in main part on the wide dispersal of their seeds and eggs by animals, more especially by fresh-water birds, which have great powers of flight, and naturally travel from one piece of water to another. ON THE INHABITANTS OF OCEANIC ISLANDS. We now come to the last of the three classes of facts, which I have selected as presenting the greatest amount of difficulty with respect to distribution, on the view that not only all the individuals of the same species have migrated from some one area, but that allied species, although now inhabiting the most distant points, have proceeded from a single area, the birthplace of their early progenitors. I have already given my reasons for disbelieving in continental extensions within the period of existing species on so enormous a scale that all the many islands of the several oceans were thus stocked with their present terrestrial inhabitants. This view removes many difficulties, but it does not accord with all the facts in regard to the productions of islands. In the following remarks I shall not confine myself to the mere question of dispersal, but shall consider some other cases bearing on the truth of the two theories of independent creation and of descent with modification. The species of all kinds which inhabit oceanic islands are few in number compared with those on equal continental areas: Alph. de Candolle admits this for plants, and Wollaston for insects. New Zealand, for instance, with its lofty mountains and diversified stations, extending over 780 miles of latitude, together with the outlying islands of Auckland, Campbell and Chatham, contain altogether only 960 kinds of flowering plants; if we compare this moderate number with the species which swarm over equal areas in Southwestern Australia or at the Cape of Good Hope, we must admit that some cause, independently of different physical conditions, has given rise to so great a difference in number. Even the uniform county of Cambridge has 847 plants, and the little island of Anglesea 764, but a few ferns and a few introduced plants are included in these numbers, and the comparison in some other respects is not quite fair. We have evidence that the barren island of Ascension aboriginally possessed less than half-a-dozen flowering plants; yet many species have now become naturalised on it, as they have in New Zealand and on every other oceanic island which can be named. In St. Helena there is reason to believe that the naturalised plants and animals have nearly or quite exterminated many native productions. He who admits the doctrine of the creation of each separate species, will have to admit that a sufficient number of the best adapted plants and animals were not created for oceanic islands; for man has unintentionally stocked them far more fully and perfectly than did nature. Although in oceanic islands the species are few in number, the proportion of endemic kinds (i.e. those found nowhere else in the world) is often extremely large. If we compare, for instance, the number of endemic land-shells in Madeira, or of endemic birds in the Galapagos Archipelago, with the number found on any continent, and then compare the area of the island with that of the continent, we shall see that this is true. This fact might have been theoretically expected, for, as already explained, species occasionally arriving, after long intervals of time in the new and isolated district, and having to compete with new associates, would be eminently liable to modification, and would often produce groups of modified descendants. But it by no means follows that, because in an island nearly all the species of one class are peculiar, those of another class, or of another section of the same class, are peculiar; and this difference seems to depend partly on the species which are not modified having immigrated in a body, so that their mutual relations have not been much disturbed; and partly on the frequent arrival of unmodified immigrants from the mother-country, with which the insular forms have intercrossed. It should be borne in mind that the offspring of such crosses would certainly gain in vigour; so that even an occasional cross would produce more effect than might have been anticipated. I will give a few illustrations of the foregoing remarks: in the Galapagos Islands there are twenty-six land birds; of these twenty-one (or perhaps twenty-three) are peculiar; whereas of the eleven marine birds only two are peculiar; and it is obvious that marine birds could arrive at these islands much more easily and frequently than land-birds. Bermuda, on the other hand, which lies at about the same distance from North America as the Galapagos Islands do from South America, and which has a very peculiar soil, does not possess a single endemic land bird; and we know from Mr. J.M. Jones's admirable account of Bermuda, that very many North American birds occasionally or even frequently visit this island. Almost every year, as I am informed by Mr. E.V. Harcourt, many European and African birds are blown to Madeira; this island is inhabited by ninety-nine kinds, of which one alone is peculiar, though very closely related to a European form; and three or four other species are confined to this island and to the Canaries. So that the islands of Bermuda and Madeira have been stocked from the neighbouring continents with birds, which for long ages have there struggled together, and have become mutually co-adapted. Hence, when settled in their new homes, each kind will have been kept by the others to its proper place and habits, and will consequently have been but little liable to modification. Any tendency to modification will also have been checked by intercrossing with the unmodified immigrants, often arriving from the mother-country. Madeira again is inhabited by a wonderful number of peculiar land-shells, whereas not one species of sea-shell is peculiar to its shores: now, though we do not know how sea-shells are dispersed, yet we can see that their eggs or larvae, perhaps attached to seaweed or floating timber, or to the feet of wading birds, might be transported across three or four hundred miles of open sea far more easily than land-shells. The different orders of insects inhabiting Madeira present nearly parallel cases. Oceanic islands are sometimes deficient in animals of certain whole classes, and their places are occupied by other classes; thus in the Galapagos Islands reptiles, and in New Zealand gigantic wingless birds, take, or recently took, the place of mammals. Although New Zealand is here spoken of as an oceanic island, it is in some degree doubtful whether it should be so ranked; it is of large size, and is not separated from Australia by a profoundly deep sea; from its geological character and the direction of its mountain ranges, the Rev. W.B. Clarke has lately maintained that this island, as well as New Caledonia, should be considered as appurtenances of Australia. Turning to plants, Dr. Hooker has shown that in the Galapagos Islands the proportional numbers of the different orders are very different from what they are elsewhere. All such differences in number, and the absence of certain whole groups of animals and plants, are generally accounted for by supposed differences in the physical conditions of the islands; but this explanation is not a little doubtful. Facility of immigration seems to have been fully as important as the nature of the conditions. Many remarkable little facts could be given with respect to the inhabitants of oceanic islands. For instance, in certain islands not tenanted by a single mammal, some of the endemic plants have beautifully hooked seeds; yet few relations are more manifest than that hooks serve for the transportal of seeds in the wool or fur of quadrupeds. But a hooked seed might be carried to an island by other means; and the plant then becoming modified would form an endemic species, still retaining its hooks, which would form a useless appendage, like the shrivelled wings under the soldered wing-covers of many insular beetles. Again, islands often possess trees or bushes belonging to orders which elsewhere include only herbaceous species; now trees, as Alph. de Candolle has shown, generally have, whatever the cause may be, confined ranges. Hence trees would be little likely to reach distant oceanic islands; and an herbaceous plant, which had no chance of successfully competing with the many fully developed trees growing on a continent, might, when established on an island, gain an advantage over other herbaceous plants by growing taller and taller and overtopping them. In this case, natural selection would tend to add to the stature of the plant, to whatever order it belonged, and thus first convert it into a bush and then into a tree. ABSENCE OF BATRACHIANS AND TERRESTRIAL MAMMALS ON OCEANIC ISLANDS. With respect to the absence of whole orders of animals on oceanic islands, Bory St. Vincent long ago remarked that Batrachians (frogs, toads, newts) are never found on any of the many islands with which the great oceans are studded. I have taken pains to verify this assertion, and have found it true, with the exception of New Zealand, New Caledonia, the Andaman Islands, and perhaps the Solomon Islands and the Seychelles. But I have already remarked that it is doubtful whether New Zealand and New Caledonia ought to be classed as oceanic islands; and this is still more doubtful with respect to the Andaman and Solomon groups and the Seychelles. This general absence of frogs, toads and newts on so many true oceanic islands cannot be accounted for by their physical conditions; indeed it seems that islands are peculiarly fitted for these animals; for frogs have been introduced into Madeira, the Azores, and Mauritius, and have multiplied so as to become a nuisance. But as these animals and their spawn are immediately killed (with the exception, as far as known, of one Indian species) by sea-water, there would be great difficulty in their transportal across the sea, and therefore we can see why they do not exist on strictly oceanic islands. But why, on the theory of creation, they should not have been created there, it would be very difficult to explain. Mammals offer another and similar case. I have carefully searched the oldest voyages, and have not found a single instance, free from doubt, of a terrestrial mammal (excluding domesticated animals kept by the natives) inhabiting an island situated above 300 miles from a continent or great continental island; and many islands situated at a much less distance are equally barren. The Falkland Islands, which are inhabited by a wolf-like fox, come nearest to an exception; but this group cannot be considered as oceanic, as it lies on a bank in connection with the mainland at a distance of about 280 miles; moreover, icebergs formerly brought boulders to its western shores, and they may have formerly transported foxes, as now frequently happens in the arctic regions. Yet it cannot be said that small islands will not support at least small mammals, for they occur in many parts of the world on very small islands, when lying close to a continent; and hardly an island can be named on which our smaller quadrupeds have not become naturalised and greatly multiplied. It cannot be said, on the ordinary view of creation, that there has not been time for the creation of mammals; many volcanic islands are sufficiently ancient, as shown by the stupendous degradation which they have suffered, and by their tertiary strata: there has also been time for the production of endemic species belonging to other classes; and on continents it is known that new species of mammals appear and disappear at a quicker rate than other and lower animals. Although terrestrial mammals do not occur on oceanic islands, aerial mammals do occur on almost every island. New Zealand possesses two bats found nowhere else in the world: Norfolk Island, the Viti Archipelago, the Bonin Islands, the Caroline and Marianne Archipelagoes, and Mauritius, all possess their peculiar bats. Why, it may be asked, has the supposed creative force produced bats and no other mammals on remote islands? On my view this question can easily be answered; for no terrestrial mammal can be transported across a wide space of sea, but bats can fly across. Bats have been seen wandering by day far over the Atlantic Ocean; and two North American species, either regularly or occasionally, visit Bermuda, at the distance of 600 miles from the mainland. I hear from Mr. Tomes, who has specially studied this family, that many species have enormous ranges, and are found on continents and on far distant islands. Hence, we have only to suppose that such wandering species have been modified in their new homes in relation to their new position, and we can understand the presence of endemic bats on oceanic islands, with the absence of all other terrestrial mammals. Another interesting relation exists, namely, between the depth of the sea separating islands from each other, or from the nearest continent, and the degree of affinity of their mammalian inhabitants. Mr. Windsor Earl has made some striking observations on this head, since greatly extended by Mr. Wallace's admirable researches, in regard to the great Malay Archipelago, which is traversed near Celebes by a space of deep ocean, and this separates two widely distinct mammalian faunas. On either side, the islands stand on a moderately shallow submarine bank, and these islands are inhabited by the same or by closely allied quadrupeds. I have not as yet had time to follow up this subject in all quarters of the world; but as far as I have gone, the relation holds good. For instance, Britain is separated by a shallow channel from Europe, and the mammals are the same on both sides; and so it is with all the islands near the shores of Australia. The West Indian Islands, on the other hand, stand on a deeply submerged bank, nearly one thousand fathoms in depth, and here we find American forms, but the species and even the genera are quite distinct. As the amount of modification which animals of all kinds undergo partly depends on the lapse of time, and as the islands which are separated from each other, or from the mainland, by shallow channels, are more likely to have been continuously united within a recent period than the islands separated by deeper channels, we can understand how it is that a relation exists between the depth of the sea separating two mammalian faunas, and the degree of their affinity, a relation which is quite inexplicable on the theory of independent acts of creation. The foregoing statements in regard to the inhabitants of oceanic islands, namely, the fewness of the species, with a large proportion consisting of endemic forms--the members of certain groups, but not those of other groups in the same class, having been modified--the absence of certain whole orders, as of batrachians and of terrestrial mammals, notwithstanding the presence of aerial bats, the singular proportions of certain orders of plants, herbaceous forms having been developed into trees, etc., seem to me to accord better with the belief in the efficiency of occasional means of transport, carried on during a long course of time, than with the belief in the former connection of all oceanic islands with the nearest continent; for on this latter view it is probable that the various classes would have immigrated more uniformly, and from the species having entered in a body, their mutual relations would not have been much disturbed, and consequently, they would either have not been modified, or all the species in a more equable manner. I do not deny that there are many and serious difficulties in understanding how many of the inhabitants of the more remote islands, whether still retaining the same specific form or subsequently modified, have reached their present homes. But the probability of other islands having once existed as halting-places, of which not a wreck now remains, must not be overlooked. I will specify one difficult case. Almost all oceanic islands, even the most isolated and smallest, are inhabited by land-shells, generally by endemic species, but sometimes by species found elsewhere striking instances of which have been given by Dr. A.A. Gould in relation to the Pacific. Now it is notorious that land-shells are easily killed by sea-water; their eggs, at least such as I have tried, sink in it and are killed. Yet there must be some unknown, but occasionally efficient means for their transportal. Would the just-hatched young sometimes adhere to the feet of birds roosting on the ground and thus get transported? It occurred to me that land-shells, when hybernating and having a membranous diaphragm over the mouth of the shell, might be floated in chinks of drifted timber across moderately wide arms of the sea. And I find that several species in this state withstand uninjured an immersion in sea-water during seven days. One shell, the Helix pomatia, after having been thus treated, and again hybernating, was put into sea-water for twenty days and perfectly recovered. During this length of time the shell might have been carried by a marine country of average swiftness to a distance of 660 geographical miles. As this Helix has a thick calcareous operculum I removed it, and when it had formed a new membranous one, I again immersed it for fourteen days in sea-water, and again it recovered and crawled away. Baron Aucapitaine has since tried similar experiments. He placed 100 land-shells, belonging to ten species, in a box pierced with holes, and immersed it for a fortnight in the sea. Out of the hundred shells twenty-seven recovered. The presence of an operculum seems to have been of importance, as out of twelve specimens of Cyclostoma elegans, which is thus furnished, eleven revived. It is remarkable, seeing how well the Helix pomatia resisted with me the salt-water, that not one of fifty-four specimens belonging to four other species of Helix tried by Aucapitaine recovered. It is, however, not at all probable that land-shells have often been thus transported; the feet of birds offer a more probable method. ON THE RELATIONS OF THE INHABITANTS OF ISLANDS TO THOSE OF THE NEAREST MAINLAND. The most striking and important fact for us is the affinity of the species which inhabit islands to those of the nearest mainland, without being actually the same. Numerous instances could be given. The Galapagos Archipelago, situated under the equator, lies at a distance of between 500 and 600 miles from the shores of South America. Here almost every product of the land and of the water bears the unmistakable stamp of the American continent. There are twenty-six land birds. Of these twenty-one, or perhaps twenty-three, are ranked as distinct species, and would commonly be assumed to have been here created; yet the close affinity of most of these birds to American species is manifest in every character in their habits, gestures, and tones of voice. So it is with the other animals, and with a large proportion of the plants, as shown by Dr. Hooker in his admirable Flora of this archipelago. The naturalist, looking at the inhabitants of these volcanic islands in the Pacific, distant several hundred miles from the continent, feels that he is standing on American land. Why should this be so? Why should the species which are supposed to have been created in the Galapagos Archipelago, and nowhere else, bear so plainly the stamp of affinity to those created in America? There is nothing in the conditions of life, in the geological nature of the islands, in their height or climate, or in the proportions in which the several classes are associated together, which closely resembles the conditions of the South American coast. In fact, there is a considerable dissimilarity in all these respects. On the other hand, there is a considerable degree of resemblance in the volcanic nature of the soil, in the climate, height, and size of the islands, between the Galapagos and Cape Verde Archipelagos: but what an entire and absolute difference in their inhabitants! The inhabitants of the Cape Verde Islands are related to those of Africa, like those of the Galapagos to America. Facts, such as these, admit of no sort of explanation on the ordinary view of independent creation; whereas, on the view here maintained, it is obvious that the Galapagos Islands would be likely to receive colonists from America, whether by occasional means of transport or (though I do not believe in this doctrine) by formerly continuous land, and the Cape Verde Islands from Africa; such colonists would be liable to modification--the principle of inheritance still betraying their original birthplace. Many analogous facts could be given: indeed it is an almost universal rule that the endemic productions of islands are related to those of the nearest continent, or of the nearest large island. The exceptions are few, and most of them can be explained. Thus, although Kerguelen Land stands nearer to Africa than to America, the plants are related, and that very closely, as we know from Dr. Hooker's account, to those of America: but on the view that this island has been mainly stocked by seeds brought with earth and stones on icebergs, drifted by the prevailing currents, this anomaly disappears. New Zealand in its endemic plants is much more closely related to Australia, the nearest mainland, than to any other region: and this is what might have been expected; but it is also plainly related to South America, which, although the next nearest continent, is so enormously remote, that the fact becomes an anomaly. But this difficulty partially disappears on the view that New Zealand, South America, and the other southern lands, have been stocked in part from a nearly intermediate though distant point, namely, from the antarctic islands, when they were clothed with vegetation, during a warmer tertiary period, before the commencement of the last Glacial period. The affinity, which, though feeble, I am assured by Dr. Hooker is real, between the flora of the south-western corner of Australia and of the Cape of Good Hope, is a far more remarkable case; but this affinity is confined to the plants, and will, no doubt, some day be explained. The same law which has determined the relationship between the inhabitants of islands and the nearest mainland, is sometimes displayed on a small scale, but in a most interesting manner, within the limits of the same archipelago. Thus each separate island of the Galapagos Archipelago is tenanted, and the fact is a marvellous one, by many distinct species; but these species are related to each other in a very much closer manner than to the inhabitants of the American continent, or of any other quarter of the world. This is what might have been expected, for islands situated so near to each other would almost necessarily receive immigrants from the same original source, and from each other. But how is it that many of the immigrants have been differently modified, though only in a small degree, in islands situated within sight of each other, having the same geological nature, the same height, climate, etc? This long appeared to me a great difficulty: but it arises in chief part from the deeply-seated error of considering the physical conditions of a country as the most important; whereas it cannot be disputed that the nature of the other species with which each has to compete, is at least as important, and generally a far more important element of success. Now if we look to the species which inhabit the Galapagos Archipelago, and are likewise found in other parts of the world, we find that they differ considerably in the several islands. This difference might indeed have been expected if the islands have been stocked by occasional means of transport--a seed, for instance, of one plant having been brought to one island, and that of another plant to another island, though all proceeding from the same general source. Hence, when in former times an immigrant first settled on one of the islands, or when it subsequently spread from one to another, it would undoubtedly be exposed to different conditions in the different islands, for it would have to compete with a different set of organisms; a plant, for instance, would find the ground best-fitted for it occupied by somewhat different species in the different islands, and would be exposed to the attacks of somewhat different enemies. If, then, it varied, natural selection would probably favour different varieties in the different islands. Some species, however, might spread and yet retain the same character throughout the group, just as we see some species spreading widely throughout a continent and remaining the same. The really surprising fact in this case of the Galapagos Archipelago, and in a lesser degree in some analogous cases, is that each new species after being formed in any one island, did not spread quickly to the other islands. But the islands, though in sight of each other, are separated by deep arms of the sea, in most cases wider than the British Channel, and there is no reason to suppose that they have at any former period been continuously united. The currents of the sea are rapid and deep between the islands, and gales of wind are extraordinarily rare; so that the islands are far more effectually separated from each other than they appear on a map. Nevertheless, some of the species, both of those found in other parts of the world and of those confined to the archipelago, are common to the several islands; and we may infer from the present manner of distribution that they have spread from one island to the others. But we often take, I think, an erroneous view of the probability of closely allied species invading each other's territory, when put into free intercommunication. Undoubtedly, if one species has any advantage over another, it will in a very brief time wholly or in part supplant it; but if both are equally well fitted for their own places, both will probably hold their separate places for almost any length of time. Being familiar with the fact that many species, naturalised through man's agency, have spread with astonishing rapidity over wide areas, we are apt to infer that most species would thus spread; but we should remember that the species which become naturalised in new countries are not generally closely allied to the aboriginal inhabitants, but are very distinct forms, belonging in a large proportion of cases, as shown by Alph. de Candolle, to distinct genera. In the Galapagos Archipelago, many even of the birds, though so well adapted for flying from island to island, differ on the different islands; thus there are three closely allied species of mocking-thrush, each confined to its own island. Now let us suppose the mocking-thrush of Chatham Island to be blown to Charles Island, which has its own mocking-thrush; why should it succeed in establishing itself there? We may safely infer that Charles Island is well stocked with its own species, for annually more eggs are laid and young birds hatched than can possibly be reared; and we may infer that the mocking-thrush peculiar to Charles Island is at least as well fitted for its home as is the species peculiar to Chatham Island. Sir C. Lyell and Mr. Wollaston have communicated to me a remarkable fact bearing on this subject; namely, that Madeira and the adjoining islet of Porto Santo possess many distinct but representative species of land-shells, some of which live in crevices of stone; and although large quantities of stone are annually transported from Porto Santo to Madeira, yet this latter island has not become colonised by the Porto Santo species: nevertheless, both islands have been colonised by some European land-shells, which no doubt had some advantage over the indigenous species. From these considerations I think we need not greatly marvel at the endemic species which inhabit the several islands of the Galapagos Archipelago not having all spread from island to island. On the same continent, also, pre-occupation has probably played an important part in checking the commingling of the species which inhabit different districts with nearly the same physical conditions. Thus, the south-east and south-west corners of Australia have nearly the same physical conditions, and are united by continuous land, yet they are inhabited by a vast number of distinct mammals, birds, and plants; so it is, according to Mr. Bates, with the butterflies and other animals inhabiting the great, open, and continuous valley of the Amazons. The same principle which governs the general character of the inhabitants of oceanic islands, namely, the relation to the source whence colonists could have been most easily derived, together with their subsequent modification, is of the widest application throughout nature. We see this on every mountain-summit, in every lake and marsh. For Alpine species, excepting in as far as the same species have become widely spread during the Glacial epoch, are related to those of the surrounding lowlands; thus we have in South America, Alpine humming-birds, Alpine rodents, Alpine plants, etc., all strictly belonging to American forms; and it is obvious that a mountain, as it became slowly upheaved, would be colonised from the surrounding lowlands. So it is with the inhabitants of lakes and marshes, excepting in so far as great facility of transport has allowed the same forms to prevail throughout large portions of the world. We see the same principle in the character of most of the blind animals inhabiting the caves of America and of Europe. Other analogous facts could be given. It will, I believe, be found universally true, that wherever in two regions, let them be ever so distant, many closely allied or representative species occur, there will likewise be found some identical species; and wherever many closely-allied species occur, there will be found many forms which some naturalists rank as distinct species, and others as mere varieties; these doubtful forms showing us the steps in the process of modification. The relation between the power and extent of migration in certain species, either at the present or at some former period, and the existence at remote points of the world of closely allied species, is shown in another and more general way. Mr. Gould remarked to me long ago, that in those genera of birds which range over the world, many of the species have very wide ranges. I can hardly doubt that this rule is generally true, though difficult of proof. Among mammals, we see it strikingly displayed in Bats, and in a lesser degree in the Felidae and Canidae. We see the same rule in the distribution of butterflies and beetles. So it is with most of the inhabitants of fresh water, for many of the genera in the most distinct classes range over the world, and many of the species have enormous ranges. It is not meant that all, but that some of the species have very wide ranges in the genera which range very widely. Nor is it meant that the species in such genera have, on an average, a very wide range; for this will largely depend on how far the process of modification has gone; for instance, two varieties of the same species inhabit America and Europe, and thus the species has an immense range; but, if variation were to be carried a little further, the two varieties would be ranked as distinct species, and their range would be greatly reduced. Still less is it meant, that species which have the capacity of crossing barriers and ranging widely, as in the case of certain powerfully-winged birds, will necessarily range widely; for we should never forget that to range widely implies not only the power of crossing barriers, but the more important power of being victorious in distant lands in the struggle for life with foreign associates. But according to the view that all the species of a genus, though distributed to the most remote points of the world, are descended from a single progenitor, we ought to find, and I believe as a general rule we do find, that some at least of the species range very widely. We should bear in mind that many genera in all classes are of ancient origin, and the species in this case will have had ample time for dispersal and subsequent modification. There is also reason to believe, from geological evidence, that within each great class the lower organisms change at a slower rate than the higher; consequently they will have had a better chance of ranging widely and of still retaining the same specific character. This fact, together with that of the seeds and eggs of most lowly organised forms being very minute and better fitted for distant transportal, probably accounts for a law which has long been observed, and which has lately been discussed by Alph. de Candolle in regard to plants, namely, that the lower any group of organisms stands the more widely it ranges. The relations just discussed--namely, lower organisms ranging more widely than the higher--some of the species of widely-ranging genera themselves ranging widely--such facts, as alpine, lacustrine, and marsh productions being generally related to those which live on the surrounding low lands and dry lands--the striking relationship between the inhabitants of islands and those of the nearest mainland--the still closer relationship of the distinct inhabitants of the islands of the same archipelago--are inexplicable on the ordinary view of the independent creation of each species, but are explicable if we admit colonisation from the nearest or readiest source, together with the subsequent adaptation of the colonists to their new homes. SUMMARY OF THE LAST AND PRESENT CHAPTERS. In these chapters I have endeavoured to show that if we make due allowance for our ignorance of the full effects of changes of climate and of the level of the land, which have certainly occurred within the recent period, and of other changes which have probably occurred--if we remember how ignorant we are with respect to the many curious means of occasional transport--if we bear in mind, and this is a very important consideration, how often a species may have ranged continuously over a wide area, and then have become extinct in the intermediate tracts--the difficulty is not insuperable in believing that all the individuals of the same species, wherever found, are descended from common parents. And we are led to this conclusion, which has been arrived at by many naturalists under the designation of single centres of creation, by various general considerations, more especially from the importance of barriers of all kinds, and from the analogical distribution of subgenera, genera, and families. With respect to distinct species belonging to the same genus, which on our theory have spread from one parent-source; if we make the same allowances as before for our ignorance, and remember that some forms of life have changed very slowly, enormous periods of time having been thus granted for their migration, the difficulties are far from insuperable; though in this case, as in that of the individuals of the same species, they are often great. As exemplifying the effects of climatical changes on distribution, I have attempted to show how important a part the last Glacial period has played, which affected even the equatorial regions, and which, during the alternations of the cold in the north and the south, allowed the productions of opposite hemispheres to mingle, and left some of them stranded on the mountain-summits in all parts of the world. As showing how diversified are the means of occasional transport, I have discussed at some little length the means of dispersal of fresh-water productions. If the difficulties be not insuperable in admitting that in the long course of time all the individuals of the same species, and likewise of the several species belonging to the same genus, have proceeded from some one source; then all the grand leading facts of geographical distribution are explicable on the theory of migration, together with subsequent modification and the multiplication of new forms. We can thus understand the high importance of barriers, whether of land or water, in not only separating but in apparently forming the several zoological and botanical provinces. We can thus understand the concentration of related species within the same areas; and how it is that under different latitudes, for instance, in South America, the inhabitants of the plains and mountains, of the forests, marshes, and deserts, are linked together in so mysterious a manner, and are likewise linked to the extinct beings which formerly inhabited the same continent. Bearing in mind that the mutual relation of organism to organism is of the highest importance, we can see why two areas, having nearly the same physical conditions, should often be inhabited by very different forms of life; for according to the length of time which has elapsed since the colonists entered one of the regions, or both; according to the nature of the communication which allowed certain forms and not others to enter, either in greater or lesser numbers; according or not as those which entered happened to come into more or less direct competition with each other and with the aborigines; and according as the immigrants were capable of varying more or less rapidly, there would ensue in the to or more regions, independently of their physical conditions, infinitely diversified conditions of life; there would be an almost endless amount of organic action and reaction, and we should find some groups of beings greatly, and some only slightly modified; some developed in great force, some existing in scanty numbers--and this we do find in the several great geographical provinces of the world. On these same principles we can understand, as I have endeavoured to show, why oceanic islands should have few inhabitants, but that of these, a large proportion should be endemic or peculiar; and why, in relation to the means of migration, one group of beings should have all its species peculiar, and another group, even within the same class, should have all its species the same with those in an adjoining quarter of the world. We can see why whole groups of organisms, as batrachians and terrestrial mammals, should be absent from oceanic islands, whilst the most isolated islands should possess their own peculiar species of aerial mammals or bats. We can see why, in islands, there should be some relation between the presence of mammals, in a more or less modified condition, and the depth of the sea between such islands and the mainland. We can clearly see why all the inhabitants of an archipelago, though specifically distinct on the several islets, should be closely related to each other, and should likewise be related, but less closely, to those of the nearest continent, or other source whence immigrants might have been derived. We can see why, if there exist very closely allied or representative species in two areas, however distant from each other, some identical species will almost always there be found. As the late Edward Forbes often insisted, there is a striking parallelism in the laws of life throughout time and space; the laws governing the succession of forms in past times being nearly the same with those governing at the present time the differences in different areas. We see this in many facts. The endurance of each species and group of species is continuous in time; for the apparent exceptions to the rule are so few that they may fairly be attributed to our not having as yet discovered in an intermediate deposit certain forms which are absent in it, but which occur above and below: so in space, it certainly is the general rule that the area inhabited by a single species, or by a group of species, is continuous, and the exceptions, which are not rare, may, as I have attempted to show, be accounted for by former migrations under different circumstances, or through occasional means of transport, or by the species having become extinct in the intermediate tracts. Both in time and space species and groups of species have their points of maximum development. Groups of species, living during the same period of time, or living within the same area, are often characterised by trifling features in common, as of sculpture or colour. In looking to the long succession of past ages, as in looking to distant provinces throughout the world, we find that species in certain classes differ little from each other, whilst those in another class, or only in a different section of the same order, differ greatly from each other. In both time and space the lowly organised members of each class generally change less than the highly organised; but there are in both cases marked exceptions to the rule. According to our theory, these several relations throughout time and space are intelligible; for whether we look to the allied forms of life which have changed during successive ages, or to those which have changed after having migrated into distant quarters, in both cases they are connected by the same bond of ordinary generation; in both cases the laws of variation have been the same, and modifications have been accumulated by the same means of natural selection. CHAPTER XIV. MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY--EMBRYOLOGY--RUDIMENTARY ORGANS. Classification, groups subordinate to groups--Natural system--Rules and difficulties in classification, explained on the theory of descent with modification--Classification of varieties--Descent always used in classification--Analogical or adaptive characters--Affinities, general, complex and radiating--Extinction separates and defines groups--Morphology, between members of the same class, between parts of the same individual--Embryology, laws of, explained by variations not supervening at an early age, and being inherited at a corresponding age--Rudimentary organs; their origin explained--Summary. CLASSIFICATION. From the most remote period in the history of the world organic beings have been found to resemble each other in descending degrees, so that they can be classed in groups under groups. This classification is not arbitrary like the grouping of the stars in constellations. The existence of groups would have been of simple significance, if one group had been exclusively fitted to inhabit the land, and another the water; one to feed on flesh, another on vegetable matter, and so on; but the case is widely different, for it is notorious how commonly members of even the same subgroup have different habits. In the second and fourth chapters, on Variation and on Natural Selection, I have attempted to show that within each country it is the widely ranging, the much diffused and common, that is the dominant species, belonging to the larger genera in each class, which vary most. The varieties, or incipient species, thus produced, ultimately become converted into new and distinct species; and these, on the principle of inheritance, tend to produce other new and dominant species. Consequently the groups which are now large, and which generally include many dominant species, tend to go on increasing in size. I further attempted to show that from the varying descendants of each species trying to occupy as many and as different places as possible in the economy of nature, they constantly tend to diverge in character. This latter conclusion is supported by observing the great diversity of forms, which, in any small area, come into the closest competition, and by certain facts in naturalisation. I attempted also to show that there is a steady tendency in the forms which are increasing in number and diverging in character, to supplant and exterminate the preceding, less divergent and less improved forms. I request the reader to turn to the diagram illustrating the action, as formerly explained, of these several principles; and he will see that the inevitable result is, that the modified descendants proceeding from one progenitor become broken up into groups subordinate to groups. In the diagram each letter on the uppermost line may represent a genus including several species; and the whole of the genera along this upper line form together one class, for all are descended from one ancient parent, and, consequently, have inherited something in common. But the three genera on the left hand have, on this same principle, much in common, and form a subfamily, distinct from that containing the next two genera on the right hand, which diverged from a common parent at the fifth stage of descent. These five genera have also much in common, though less than when grouped in subfamilies; and they form a family distinct from that containing the three genera still further to the right hand, which diverged at an earlier period. And all these genera, descended from (A), form an order distinct from the genera descended from (I). So that we here have many species descended from a single progenitor grouped into genera; and the genera into subfamilies, families and orders, all under one great class. The grand fact of the natural subordination of organic beings in groups under groups, which, from its familiarity, does not always sufficiently strike us, is in my judgment thus explained. No doubt organic beings, like all other objects, can be classed in many ways, either artificially by single characters, or more naturally by a number of characters. We know, for instance, that minerals and the elemental substances can be thus arranged. In this case there is of course no relation to genealogical succession, and no cause can at present be assigned for their falling into groups. But with organic beings the case is different, and the view above given accords with their natural arrangement in group under group; and no other explanation has ever been attempted. Naturalists, as we have seen, try to arrange the species, genera and families in each class, on what is called the Natural System. But what is meant by this system? Some authors look at it merely as a scheme for arranging together those living objects which are most alike, and for separating those which are most unlike; or as an artificial method of enunciating, as briefly as possible, general propositions--that is, by one sentence to give the characters common, for instance, to all mammals, by another those common to all carnivora, by another those common to the dog-genus, and then, by adding a single sentence, a full description is given of each kind of dog. The ingenuity and utility of this system are indisputable. But many naturalists think that something more is meant by the Natural System; they believe that it reveals the plan of the Creator; but unless it be specified whether order in time or space, or both, or what else is meant by the plan of the Creator, it seems to me that nothing is thus added to our knowledge. Expressions such as that famous one by Linnaeus, which we often meet with in a more or less concealed form, namely, that the characters do not make the genus, but that the genus gives the characters, seem to imply that some deeper bond is included in our classifications than mere resemblance. I believe that this is the case, and that community of descent--the one known cause of close similarity in organic beings--is the bond, which, though observed by various degrees of modification, is partially revealed to us by our classifications. Let us now consider the rules followed in classification, and the difficulties which are encountered on the view that classification either gives some unknown plan of creation, or is simply a scheme for enunciating general propositions and of placing together the forms most like each other. It might have been thought (and was in ancient times thought) that those parts of the structure which determined the habits of life, and the general place of each being in the economy of nature, would be of very high importance in classification. Nothing can be more false. No one regards the external similarity of a mouse to a shrew, of a dugong to a whale, of a whale to a fish, as of any importance. These resemblances, though so intimately connected with the whole life of the being, are ranked as merely "adaptive or analogical characters;" but to the consideration of these resemblances we shall recur. It may even be given as a general rule, that the less any part of the organisation is concerned with special habits, the more important it becomes for classification. As an instance: Owen, in speaking of the dugong, says, "The generative organs, being those which are most remotely related to the habits and food of an animal, I have always regarded as affording very clear indications of its true affinities. We are least likely in the modifications of these organs to mistake a merely adaptive for an essential character." With plants how remarkable it is that the organs of vegetation, on which their nutrition and life depend, are of little signification; whereas the organs of reproduction, with their product the seed and embryo, are of paramount importance! So again, in formerly discussing certain morphological characters which are not functionally important, we have seen that they are often of the highest service in classification. This depends on their constancy throughout many allied groups; and their constancy chiefly depends on any slight deviations not having been preserved and accumulated by natural selection, which acts only on serviceable characters. That the mere physiological importance of an organ does not determine its classificatory value, is almost proved by the fact, that in allied groups, in which the same organ, as we have every reason to suppose, has nearly the same physiological value, its classificatory value is widely different. No naturalist can have worked at any group without being struck with this fact; and it has been fully acknowledged in the writings of almost every author. It will suffice to quote the highest authority, Robert Brown, who, in speaking of certain organs in the Proteaceae, says their generic importance, "like that of all their parts, not only in this, but, as I apprehend in every natural family, is very unequal, and in some cases seems to be entirely lost." Again, in another work he says, the genera of the Connaraceae "differ in having one or more ovaria, in the existence or absence of albumen, in the imbricate or valvular aestivation. Any one of these characters singly is frequently of more than generic importance, though here even, when all taken together, they appear insufficient to separate Cnestis from Connarus." To give an example among insects: in one great division of the Hymenoptera, the antennae, as Westwood has remarked, are most constant in structure; in another division they differ much, and the differences are of quite subordinate value in classification; yet no one will say that the antennae in these two divisions of the same order are of unequal physiological importance. Any number of instances could be given of the varying importance for classification of the same important organ within the same group of beings. Again, no one will say that rudimentary or atrophied organs are of high physiological or vital importance; yet, undoubtedly, organs in this condition are often of much value in classification. No one will dispute that the rudimentary teeth in the upper jaws of young ruminants, and certain rudimentary bones of the leg, are highly serviceable in exhibiting the close affinity between Ruminants and Pachyderms. Robert Brown has strongly insisted on the fact that the position of the rudimentary florets is of the highest importance in the classification of the Grasses. Numerous instances could be given of characters derived from parts which must be considered of very trifling physiological importance, but which are universally admitted as highly serviceable in the definition of whole groups. For instance, whether or not there is an open passage from the nostrils to the mouth, the only character, according to Owen, which absolutely distinguishes fishes and reptiles--the inflection of the angle of the lower jaw in Marsupials--the manner in which the wings of insects are folded--mere colour in certain Algae--mere pubescence on parts of the flower in grasses--the nature of the dermal covering, as hair or feathers, in the Vertebrata. If the Ornithorhynchus had been covered with feathers instead of hair, this external and trifling character would have been considered by naturalists as an important aid in determining the degree of affinity of this strange creature to birds. The importance, for classification, of trifling characters, mainly depends on their being correlated with many other characters of more or less importance. The value indeed of an aggregate of characters is very evident in natural history. Hence, as has often been remarked, a species may depart from its allies in several characters, both of high physiological importance, and of almost universal prevalence, and yet leave us in no doubt where it should be ranked. Hence, also, it has been found that a classification founded on any single character, however important that may be, has always failed; for no part of the organisation is invariably constant. The importance of an aggregate of characters, even when none are important, alone explains the aphorism enunciated by Linnaeus, namely, that the characters do not give the genus, but the genus gives the character; for this seems founded on the appreciation of many trifling points of resemblance, too slight to be defined. Certain plants, belonging to the Malpighiaceae, bear perfect and degraded flowers; in the latter, as A. de Jussieu has remarked, "The greater number of the characters proper to the species, to the genus, to the family, to the class, disappear, and thus laugh at our classification." When Aspicarpa produced in France, during several years, only these degraded flowers, departing so wonderfully in a number of the most important points of structure from the proper type of the order, yet M. Richard sagaciously saw, as Jussieu observes, that this genus should still be retained among the Malpighiaceae. This case well illustrates the spirit of our classifications. Practically, when naturalists are at work, they do not trouble themselves about the physiological value of the characters which they use in defining a group or in allocating any particular species. If they find a character nearly uniform, and common to a great number of forms, and not common to others, they use it as one of high value; if common to some lesser number, they use it as of subordinate value. This principle has been broadly confessed by some naturalists to be the true one; and by none more clearly than by that excellent botanist, Aug. St. Hilaire. If several trifling characters are always found in combination, though no apparent bond of connexion can be discovered between them, especial value is set on them. As in most groups of animals, important organs, such as those for propelling the blood, or for aerating it, or those for propagating the race, are found nearly uniform, they are considered as highly serviceable in classification; but in some groups all these, the most important vital organs, are found to offer characters of quite subordinate value. Thus, as Fritz Muller has lately remarked, in the same group of crustaceans, Cypridina is furnished with a heart, while in two closely allied genera, namely Cypris and Cytherea, there is no such organ; one species of Cypridina has well-developed branchiae, while another species is destitute of them. We can see why characters derived from the embryo should be of equal importance with those derived from the adult, for a natural classification of course includes all ages. But it is by no means obvious, on the ordinary view, why the structure of the embryo should be more important for this purpose than that of the adult, which alone plays its full part in the economy of nature. Yet it has been strongly urged by those great naturalists, Milne Edwards and Agassiz, that embryological characters are the most important of all; and this doctrine has very generally been admitted as true. Nevertheless, their importance has sometimes been exaggerated, owing to the adaptive characters of larvae not having been excluded; in order to show this, Fritz Muller arranged, by the aid of such characters alone, the great class of crustaceans, and the arrangement did not prove a natural one. But there can be no doubt that embryonic, excluding larval characters, are of the highest value for classification, not only with animals but with plants. Thus the main divisions of flowering plants are founded on differences in the embryo--on the number and position of the cotyledons, and on the mode of development of the plumule and radicle. We shall immediately see why these characters possess so high a value in classification, namely, from the natural system being genealogical in its arrangement. Our classifications are often plainly influenced by chains of affinities. Nothing can be easier than to define a number of characters common to all birds; but with crustaceans, any such definition has hitherto been found impossible. There are crustaceans at the opposite ends of the series, which have hardly a character in common; yet the species at both ends, from being plainly allied to others, and these to others, and so onwards, can be recognised as unequivocally belonging to this, and to no other class of the Articulata. Geographical distribution has often been used, though perhaps not quite logically, in classification, more especially in very large groups of closely allied forms. Temminck insists on the utility or even necessity of this practice in certain groups of birds; and it has been followed by several entomologists and botanists. Finally, with respect to the comparative value of the various groups of species, such as orders, suborders, families, subfamilies, and genera, they seem to be, at least at present, almost arbitrary. Several of the best botanists, such as Mr. Bentham and others, have strongly insisted on their arbitrary value. Instances could be given among plants and insects, of a group first ranked by practised naturalists as only a genus, and then raised to the rank of a subfamily or family; and this has been done, not because further research has detected important structural differences, at first overlooked, but because numerous allied species, with slightly different grades of difference, have been subsequently discovered. All the foregoing rules and aids and difficulties in classification may be explained, if I do not greatly deceive myself, on the view that the natural system is founded on descent with modification--that the characters which naturalists consider as showing true affinity between any two or more species, are those which have been inherited from a common parent, all true classification being genealogical--that community of descent is the hidden bond which naturalists have been unconsciously seeking, and not some unknown plan of creation, or the enunciation of general propositions, and the mere putting together and separating objects more or less alike. But I must explain my meaning more fully. I believe that the ARRANGEMENT of the groups within each class, in due subordination and relation to each other, must be strictly genealogical in order to be natural; but that the AMOUNT of difference in the several branches or groups, though allied in the same degree in blood to their common progenitor, may differ greatly, being due to the different degrees of modification which they have undergone; and this is expressed by the forms being ranked under different genera, families, sections or orders. The reader will best understand what is meant, if he will take the trouble to refer to the diagram in the fourth chapter. We will suppose the letters A to L to represent allied genera existing during the Silurian epoch, and descended from some still earlier form. In three of these genera (A, F, and I) a species has transmitted modified descendants to the present day, represented by the fifteen genera (a14 to z14) on the uppermost horizontal line. Now, all these modified descendants from a single species are related in blood or descent in the same degree. They may metaphorically be called cousins to the same millionth degree, yet they differ widely and in different degrees from each other. The forms descended from A, now broken up into two or three families, constitute a distinct order from those descended from I, also broken up into two families. Nor can the existing species descended from A be ranked in the same genus with the parent A, or those from I with parent I. But the existing genus F14 may be supposed to have been but slightly modified, and it will then rank with the parent genus F; just as some few still living organisms belong to Silurian genera. So that the comparative value of the differences between these organic beings, which are all related to each other in the same degree in blood, has come to be widely different. Nevertheless, their genealogical ARRANGEMENT remains strictly true, not only at the present time, but at each successive period of descent. All the modified descendants from A will have inherited something in common from their common parent, as will all the descendants from I; so will it be with each subordinate branch of descendants at each successive stage. If, however, we suppose any descendant of A or of I to have become so much modified as to have lost all traces of its parentage in this case, its place in the natural system will be lost, as seems to have occurred with some few existing organisms. All the descendants of the genus F, along its whole line of descent, are supposed to have been but little modified, and they form a single genus. But this genus, though much isolated, will still occupy its proper intermediate position. The representation of the groups as here given in the diagram on a flat surface, is much too simple. The branches ought to have diverged in all directions. If the names of the groups had been simply written down in a linear series the representation would have been still less natural; and it is notoriously not possible to represent in a series, on a flat surface, the affinities which we discover in nature among the beings of the same group. Thus, the natural system is genealogical in its arrangement, like a pedigree. But the amount of modification which the different groups have undergone has to be expressed by ranking them under different so-called genera, subfamilies, families, sections, orders, and classes. It may be worth while to illustrate this view of classification, by taking the case of languages. If we possessed a perfect pedigree of mankind, a genealogical arrangement of the races of man would afford the best classification of the various languages now spoken throughout the world; and if all extinct languages, and all intermediate and slowly changing dialects, were to be included, such an arrangement would be the only possible one. Yet it might be that some ancient languages had altered very little and had given rise to few new languages, whilst others had altered much owing to the spreading, isolation and state of civilisation of the several co-descended races, and had thus given rise to many new dialects and languages. The various degrees of difference between the languages of the same stock would have to be expressed by groups subordinate to groups; but the proper or even the only possible arrangement would still be genealogical; and this would be strictly natural, as it would connect together all languages, extinct and recent, by the closest affinities, and would give the filiation and origin of each tongue. In confirmation of this view, let us glance at the classification of varieties, which are known or believed to be descended from a single species. These are grouped under the species, with the subvarieties under the varieties; and in some cases, as with the domestic pigeon, with several other grades of difference. Nearly the same rules are followed as in classifying species. Authors have insisted on the necessity of arranging varieties on a natural instead of an artificial system; we are cautioned, for instance, not to class two varieties of the pine-apple together, merely because their fruit, though the most important part, happens to be nearly identical; no one puts the Swedish and common turnip together, though the esculent and thickened stems are so similar. Whatever part is found to be most constant, is used in classing varieties: thus the great agriculturist Marshall says the horns are very useful for this purpose with cattle, because they are less variable than the shape or colour of the body, etc.; whereas with sheep the horns are much less serviceable, because less constant. In classing varieties, I apprehend that if we had a real pedigree, a genealogical classification would be universally preferred; and it has been attempted in some cases. For we might feel sure, whether there had been more or less modification, that the principle of inheritance would keep the forms together which were allied in the greatest number of points. In tumbler pigeons, though some of the subvarieties differ in the important character of the length of the beak, yet all are kept together from having the common habit of tumbling; but the short-faced breed has nearly or quite lost this habit; nevertheless, without any thought on the subject, these tumblers are kept in the same group, because allied in blood and alike in some other respects. With species in a state of nature, every naturalist has in fact brought descent into his classification; for he includes in his lowest grade, that of species, the two sexes; and how enormously these sometimes differ in the most important characters is known to every naturalist: scarcely a single fact can be predicated in common of the adult males and hermaphrodites of certain cirripedes, and yet no one dreams of separating them. As soon as the three Orchidean forms, Monachanthus, Myanthus, and Catasetum, which had previously been ranked as three distinct genera, were known to be sometimes produced on the same plant, they were immediately considered as varieties; and now I have been able to show that they are the male, female, and hermaphrodite forms of the same species. The naturalist includes as one species the various larval stages of the same individual, however much they may differ from each other and from the adult; as well as the so-called alternate generations of Steenstrup, which can only in a technical sense be considered as the same individual. He includes monsters and varieties, not from their partial resemblance to the parent-form, but because they are descended from it. As descent has universally been used in classing together the individuals of the same species, though the males and females and larvae are sometimes extremely different; and as it has been used in classing varieties which have undergone a certain, and sometimes a considerable amount of modification, may not this same element of descent have been unconsciously used in grouping species under genera, and genera under higher groups, all under the so-called natural system? I believe it has been unconsciously used; and thus only can I understand the several rules and guides which have been followed by our best systematists. As we have no written pedigrees, we are forced to trace community of descent by resemblances of any kind. Therefore, we choose those characters which are the least likely to have been modified, in relation to the conditions of life to which each species has been recently exposed. Rudimentary structures on this view are as good as, or even sometimes better than other parts of the organisation. We care not how trifling a character may be--let it be the mere inflection of the angle of the jaw, the manner in which an insect's wing is folded, whether the skin be covered by hair or feathers--if it prevail throughout many and different species, especially those having very different habits of life, it assumes high value; for we can account for its presence in so many forms with such different habits, only by inheritance from a common parent. We may err in this respect in regard to single points of structure, but when several characters, let them be ever so trifling, concur throughout a large group of beings having different habits, we may feel almost sure, on the theory of descent, that these characters have been inherited from a common ancestor; and we know that such aggregated characters have especial value in classification. We can understand why a species or a group of species may depart from its allies, in several of its most important characteristics, and yet be safely classed with them. This may be safely done, and is often done, as long as a sufficient number of characters, let them be ever so unimportant, betrays the hidden bond of community of descent. Let two forms have not a single character in common, yet, if these extreme forms are connected together by a chain of intermediate groups, we may at once infer their community of descent, and we put them all into the same class. As we find organs of high physiological importance--those which serve to preserve life under the most diverse conditions of existence--are generally the most constant, we attach especial value to them; but if these same organs, in another group or section of a group, are found to differ much, we at once value them less in our classification. We shall presently see why embryological characters are of such high classificatory importance. Geographical distribution may sometimes be brought usefully into play in classing large genera, because all the species of the same genus, inhabiting any distinct and isolated region, are in all probability descended from the same parents. ANALOGICAL RESEMBLANCES. We can understand, on the above views, the very important distinction between real affinities and analogical or adaptive resemblances. Lamarck first called attention to this subject, and he has been ably followed by Macleay and others. The resemblance in the shape of the body and in the fin-like anterior limbs between dugongs and whales, and between these two orders of mammals and fishes, are analogical. So is the resemblance between a mouse and a shrew-mouse (Sorex), which belong to different orders; and the still closer resemblance, insisted on by Mr. Mivart, between the mouse and a small marsupial animal (Antechinus) of Australia. These latter resemblances may be accounted for, as it seems to me, by adaptation for similarly active movements through thickets and herbage, together with concealment from enemies. Among insects there are innumerable instances; thus Linnaeus, misled by external appearances, actually classed an homopterous insect as a moth. We see something of the same kind even with our domestic varieties, as in the strikingly similar shape of the body in the improved breeds of the Chinese and common pig, which are descended from distinct species; and in the similarly thickened stems of the common and specifically distinct Swedish turnip. The resemblance between the greyhound and race-horse is hardly more fanciful than the analogies which have been drawn by some authors between widely different animals. On the view of characters being of real importance for classification, only in so far as they reveal descent, we can clearly understand why analogical or adaptive characters, although of the utmost importance to the welfare of the being, are almost valueless to the systematist. For animals, belonging to two most distinct lines of descent, may have become adapted to similar conditions, and thus have assumed a close external resemblance; but such resemblances will not reveal--will rather tend to conceal their blood-relationship. We can thus also understand the apparent paradox, that the very same characters are analogical when one group is compared with another, but give true affinities when the members of the same group are compared together: thus the shape of the body and fin-like limbs are only analogical when whales are compared with fishes, being adaptations in both classes for swimming through the water; but between the the several members of the whale family, the shape of the body and the fin-like limbs offer characters exhibiting true affinity; for as these parts are so nearly similar throughout the whole family, we cannot doubt that they have been inherited from a common ancestor. So it is with fishes. Numerous cases could be given of striking resemblances in quite distinct beings between single parts or organs, which have been adapted for the same functions. A good instance is afforded by the close resemblance of the jaws of the dog and Tasmanian wolf or Thylacinus--animals which are widely sundered in the natural system. But this resemblance is confined to general appearance, as in the prominence of the canines, and in the cutting shape of the molar teeth. For the teeth really differ much: thus the dog has on each side of the upper jaw four pre-molars and only two molars; while the Thylacinus has three pre-molars and four molars. The molars also differ much in the two animals in relative size and structure. The adult dentition is preceded by a widely different milk dentition. Any one may, of course, deny that the teeth in either case have been adapted for tearing flesh, through the natural selection of successive variations; but if this be admitted in the one case, it is unintelligible to me that it should be denied in the other. I am glad to find that so high an authority as Professor Flower has come to this same conclusion. The extraordinary cases given in a former chapter, of widely different fishes possessing electric organs--of widely different insects possessing luminous organs--and of orchids and asclepiads having pollen-masses with viscid discs, come under this same head of analogical resemblances. But these cases are so wonderful that they were introduced as difficulties or objections to our theory. In all such cases some fundamental difference in the growth or development of the parts, and generally in their matured structure, can be detected. The end gained is the same, but the means, though appearing superficially to be the same, are essentially different. The principle formerly alluded to under the term of ANALOGICAL VARIATION has probably in these cases often come into play; that is, the members of the same class, although only distantly allied, have inherited so much in common in their constitution, that they are apt to vary under similar exciting causes in a similar manner; and this would obviously aid in the acquirement through natural selection of parts or organs, strikingly like each other, independently of their direct inheritance from a common progenitor. As species belonging to distinct classes have often been adapted by successive slight modifications to live under nearly similar circumstances--to inhabit, for instance, the three elements of land, air and water--we can perhaps understand how it is that a numerical parallelism has sometimes been observed between the subgroups of distinct classes. A naturalist, struck with a parallelism of this nature, by arbitrarily raising or sinking the value of the groups in several classes (and all our experience shows that their valuation is as yet arbitrary), could easily extend the parallelism over a wide range; and thus the septenary, quinary, quaternary and ternary classifications have probably arisen. There is another and curious class of cases in which close external resemblance does not depend on adaptation to similar habits of life, but has been gained for the sake of protection. I allude to the wonderful manner in which certain butterflies imitate, as first described by Mr. Bates, other and quite distinct species. This excellent observer has shown that in some districts of South America, where, for instance, an Ithomia abounds in gaudy swarms, another butterfly, namely, a Leptalis, is often found mingled in the same flock; and the latter so closely resembles the Ithomia in every shade and stripe of colour, and even in the shape of its wings, that Mr. Bates, with his eyes sharpened by collecting during eleven years, was, though always on his guard, continually deceived. When the mockers and the mocked are caught and compared, they are found to be very different in essential structure, and to belong not only to distinct genera, but often to distinct families. Had this mimicry occurred in only one or two instances, it might have been passed over as a strange coincidence. But, if we proceed from a district where one Leptalis imitates an Ithomia, another mocking and mocked species, belonging to the same two genera, equally close in their resemblance, may be found. Altogether no less than ten genera are enumerated, which include species that imitate other butterflies. The mockers and mocked always inhabit the same region; we never find an imitator living remote from the form which it imitates. The mockers are almost invariably rare insects; the mocked in almost every case abounds in swarms. In the same district in which a species of Leptalis closely imitates an Ithomia, there are sometimes other Lepidoptera mimicking the same Ithomia: so that in the same place, species of three genera of butterflies and even a moth are found all closely resembling a butterfly belonging to a fourth genus. It deserves especial notice that many of the mimicking forms of the Leptalis, as well as of the mimicked forms, can be shown by a graduated series to be merely varieties of the same species; while others are undoubtedly distinct species. But why, it may be asked, are certain forms treated as the mimicked and others as the mimickers? Mr. Bates satisfactorily answers this question by showing that the form which is imitated keeps the usual dress of the group to which it belongs, while the counterfeiters have changed their dress and do not resemble their nearest allies. We are next led to enquire what reason can be assigned for certain butterflies and moths so often assuming the dress of another and quite distinct form; why, to the perplexity of naturalists, has nature condescended to the tricks of the stage? Mr. Bates has, no doubt, hit on the true explanation. The mocked forms, which always abound in numbers, must habitually escape destruction to a large extent, otherwise they could not exist in such swarms; and a large amount of evidence has now been collected, showing that they are distasteful to birds and other insect-devouring animals. The mocking forms, on the other hand, that inhabit the same district, are comparatively rare, and belong to rare groups; hence, they must suffer habitually from some danger, for otherwise, from the number of eggs laid by all butterflies, they would in three or four generations swarm over the whole country. Now if a member of one of these persecuted and rare groups were to assume a dress so like that of a well-protected species that it continually deceived the practised eyes of an entomologist, it would often deceive predaceous birds and insects, and thus often escape destruction. Mr. Bates may almost be said to have actually witnessed the process by which the mimickers have come so closely to resemble the mimicked; for he found that some of the forms of Leptalis which mimic so many other butterflies, varied in an extreme degree. In one district several varieties occurred, and of these one alone resembled, to a certain extent, the common Ithomia of the same district. In another district there were two or three varieties, one of which was much commoner than the others, and this closely mocked another form of Ithomia. From facts of this nature, Mr. Bates concludes that the Leptalis first varies; and when a variety happens to resemble in some degree any common butterfly inhabiting the same district, this variety, from its resemblance to a flourishing and little persecuted kind, has a better chance of escaping destruction from predaceous birds and insects, and is consequently oftener preserved; "the less perfect degrees of resemblance being generation after generation eliminated, and only the others left to propagate their kind." So that here we have an excellent illustration of natural selection. Messrs. Wallace and Trimen have likewise described several equally striking cases of imitation in the Lepidoptera of the Malay Archipelago and Africa, and with some other insects. Mr. Wallace has also detected one such case with birds, but we have none with the larger quadrupeds. The much greater frequency of imitation with insects than with other animals, is probably the consequence of their small size; insects cannot defend themselves, excepting indeed the kinds furnished with a sting, and I have never heard of an instance of such kinds mocking other insects, though they are mocked; insects cannot easily escape by flight from the larger animals which prey on them; therefore, speaking metaphorically, they are reduced, like most weak creatures, to trickery and dissimulation. It should be observed that the process of imitation probably never commenced between forms widely dissimilar in colour. But, starting with species already somewhat like each other, the closest resemblance, if beneficial, could readily be gained by the above means, and if the imitated form was subsequently and gradually modified through any agency, the imitating form would be led along the same track, and thus be altered to almost any extent, so that it might ultimately assume an appearance or colouring wholly unlike that of the other members of the family to which it belonged. There is, however, some difficulty on this head, for it is necessary to suppose in some cases that ancient members belonging to several distinct groups, before they had diverged to their present extent, accidentally resembled a member of another and protected group in a sufficient degree to afford some slight protection, this having given the basis for the subsequent acquisition of the most perfect resemblance. ON THE NATURE OF THE AFFINITIES CONNECTING ORGANIC BEINGS. As the modified descendants of dominant species, belonging to the larger genera, tend to inherit the advantages which made the groups to which they belong large and their parents dominant, they are almost sure to spread widely, and to seize on more and more places in the economy of nature. The larger and more dominant groups within each class thus tend to go on increasing in size, and they consequently supplant many smaller and feebler groups. Thus, we can account for the fact that all organisms, recent and extinct, are included under a few great orders and under still fewer classes. As showing how few the higher groups are in number, and how widely they are spread throughout the world, the fact is striking that the discovery of Australia has not added an insect belonging to a new class, and that in the vegetable kingdom, as I learn from Dr. Hooker, it has added only two or three families of small size. In the chapter on geological succession I attempted to show, on the principle of each group having generally diverged much in character during the long-continued process of modification, how it is that the more ancient forms of life often present characters in some degree intermediate between existing groups. As some few of the old and intermediate forms having transmitted to the present day descendants but little modified, these constitute our so-called osculant or aberrant groups. The more aberrant any form is, the greater must be the number of connecting forms which have been exterminated and utterly lost. And we have evidence of aberrant groups having suffered severely from extinction, for they are almost always represented by extremely few species; and such species as do occur are generally very distinct from each other, which again implies extinction. The genera Ornithorhynchus and Lepidosiren, for example, would not have been less aberrant had each been represented by a dozen species, instead of as at present by a single one, or by two or three. We can, I think, account for this fact only by looking at aberrant groups as forms which have been conquered by more successful competitors, with a few members still preserved under unusually favourable conditions. Mr. Waterhouse has remarked that when a member belonging to one group of animals exhibits an affinity to a quite distinct group, this affinity in most cases is general and not special: thus, according to Mr. Waterhouse, of all Rodents, the bizcacha is most nearly related to Marsupials; but in the points in which it approaches this order, its relations are general, that is, not to any one Marsupial species more than to another. As these points of affinity are believed to be real and not merely adaptive, they must be due in accordance with our view to inheritance from a common progenitor. Therefore, we must suppose either that all Rodents, including the bizcacha, branched off from some ancient Marsupial, which will naturally have been more or less intermediate in character with respect to all existing Marsupials; or that both Rodents and Marsupials branched off from a common progenitor, and that both groups have since undergone much modification in divergent directions. On either view we must suppose that the bizcacha has retained, by inheritance, more of the character of its ancient progenitor than have other Rodents; and therefore it will not be specially related to any one existing Marsupial, but indirectly to all or nearly all Marsupials, from having partially retained the character of their common progenitor, or of some early member of the group. On the other hand, of all Marsupials, as Mr. Waterhouse has remarked, the Phascolomys resembles most nearly, not any one species, but the general order of Rodents. In this case, however, it may be strongly suspected that the resemblance is only analogical, owing to the Phascolomys having become adapted to habits like those of a Rodent. The elder De Candolle has made nearly similar observations on the general nature of the affinities of distinct families of plants. On the principle of the multiplication and gradual divergence in character of the species descended from a common progenitor, together with their retention by inheritance of some characters in common, we can understand the excessively complex and radiating affinities by which all the members of the same family or higher group are connected together. For the common progenitor of a whole family, now broken up by extinction into distinct groups and subgroups, will have transmitted some of its characters, modified in various ways and degrees, to all the species; and they will consequently be related to each other by circuitous lines of affinity of various lengths (as may be seen in the diagram so often referred to), mounting up through many predecessors. As it is difficult to show the blood-relationship between the numerous kindred of any ancient and noble family, even by the aid of a genealogical tree, and almost impossible to do so without this aid, we can understand the extraordinary difficulty which naturalists have experienced in describing, without the aid of a diagram, the various affinities which they perceive between the many living and extinct members of the same great natural class. Extinction, as we have seen in the fourth chapter, has played an important part in defining and widening the intervals between the several groups in each class. We may thus account for the distinctness of whole classes from each other--for instance, of birds from all other vertebrate animals--by the belief that many ancient forms of life have been utterly lost, through which the early progenitors of birds were formerly connected with the early progenitors of the other and at that time less differentiated vertebrate classes. There has been much less extinction of the forms of life which once connected fishes with Batrachians. There has been still less within some whole classes, for instance the Crustacea, for here the most wonderfully diverse forms are still linked together by a long and only partially broken chain of affinities. Extinction has only defined the groups: it has by no means made them; for if every form which has ever lived on this earth were suddenly to reappear, though it would be quite impossible to give definitions by which each group could be distinguished, still a natural classification, or at least a natural arrangement, would be possible. We shall see this by turning to the diagram: the letters, A to L, may represent eleven Silurian genera, some of which have produced large groups of modified descendants, with every link in each branch and sub-branch still alive; and the links not greater than those between existing varieties. In this case it would be quite impossible to give definitions by which the several members of the several groups could be distinguished from their more immediate parents and descendants. Yet the arrangement in the diagram would still hold good and would be natural; for, on the principle of inheritance, all the forms descended, for instance from A, would have something in common. In a tree we can distinguish this or that branch, though at the actual fork the two unite and blend together. We could not, as I have said, define the several groups; but we could pick out types, or forms, representing most of the characters of each group, whether large or small, and thus give a general idea of the value of the differences between them. This is what we should be driven to, if we were ever to succeed in collecting all the forms in any one class which have lived throughout all time and space. Assuredly we shall never succeed in making so perfect a collection: nevertheless, in certain classes, we are tending toward this end; and Milne Edwards has lately insisted, in an able paper, on the high importance of looking to types, whether or not we can separate and define the groups to which such types belong. Finally, we have seen that natural selection, which follows from the struggle for existence, and which almost inevitably leads to extinction and divergence of character in the descendants from any one parent-species, explains that great and universal feature in the affinities of all organic beings, namely, their subordination in group under group. We use the element of descent in classing the individuals of both sexes and of all ages under one species, although they may have but few characters in common; we use descent in classing acknowledged varieties, however different they may be from their parents; and I believe that this element of descent is the hidden bond of connexion which naturalists have sought under the term of the Natural System. On this idea of the natural system being, in so far as it has been perfected, genealogical in its arrangement, with the grades of difference expressed by the terms genera, families, orders, etc., we can understand the rules which we are compelled to follow in our classification. We can understand why we value certain resemblances far more than others; why we use rudimentary and useless organs, or others of trifling physiological importance; why, in finding the relations between one group and another, we summarily reject analogical or adaptive characters, and yet use these same characters within the limits of the same group. We can clearly see how it is that all living and extinct forms can be grouped together within a few great classes; and how the several members of each class are connected together by the most complex and radiating lines of affinities. We shall never, probably, disentangle the inextricable web of the affinities between the members of any one class; but when we have a distinct object in view, and do not look to some unknown plan of creation, we may hope to make sure but slow progress. Professor Haeckel in his "Generelle Morphologie" and in another works, has recently brought his great knowledge and abilities to bear on what he calls phylogeny, or the lines of descent of all organic beings. In drawing up the several series he trusts chiefly to embryological characters, but receives aid from homologous and rudimentary organs, as well as from the successive periods at which the various forms of life are believed to have first appeared in our geological formations. He has thus boldly made a great beginning, and shows us how classification will in the future be treated. MORPHOLOGY. We have seen that the members of the same class, independently of their habits of life, resemble each other in the general plan of their organisation. This resemblance is often expressed by the term "unity of type;" or by saying that the several parts and organs in the different species of the class are homologous. The whole subject is included under the general term of Morphology. This is one of the most interesting departments of natural history, and may almost be said to be its very soul. What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include similar bones, in the same relative positions? How curious it is, to give a subordinate though striking instance, that the hind feet of the kangaroo, which are so well fitted for bounding over the open plains--those of the climbing, leaf-eating koala, equally well fitted for grasping the branches of trees--those of the ground-dwelling, insect or root-eating, bandicoots--and those of some other Australian marsupials--should all be constructed on the same extraordinary type, namely with the bones of the second and third digits extremely slender and enveloped within the same skin, so that they appear like a single toe furnished with two claws. Notwithstanding this similarity of pattern, it is obvious that the hind feet of these several animals are used for as widely different purposes as it is possible to conceive. The case is rendered all the more striking by the American opossums, which follow nearly the same habits of life as some of their Australian relatives, having feet constructed on the ordinary plan. Professor Flower, from whom these statements are taken, remarks in conclusion: "We may call this conformity to type, without getting much nearer to an explanation of the phenomenon;" and he then adds "but is it not powerfully suggestive of true relationship, of inheritance from a common ancestor?" Geoffroy St. Hilaire has strongly insisted on the high importance of relative position or connexion in homologous parts; they may differ to almost any extent in form and size, and yet remain connected together in the same invariable order. We never find, for instance, the bones of the arm and forearm, or of the thigh and leg, transposed. Hence the same names can be given to the homologous bones in widely different animals. We see the same great law in the construction of the mouths of insects: what can be more different than the immensely long spiral proboscis of a sphinx-moth, the curious folded one of a bee or bug, and the great jaws of a beetle? Yet all these organs, serving for such widely different purposes, are formed by infinitely numerous modifications of an upper lip, mandibles, and two pairs of maxillae. The same law governs the construction of the mouths and limbs of crustaceans. So it is with the flowers of plants. Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or by the doctrine of final causes. The hopelessness of the attempt has been expressly admitted by Owen in his most interesting work on the "Nature of Limbs." On the ordinary view of the independent creation of each being, we can only say that so it is; that it has pleased the Creator to construct all the animals and plants in each great class on a uniform plan; but this is not a scientific explanation. The explanation is to a large extent simple, on the theory of the selection of successive slight modifications, each being profitable in some way to the modified form, but often affecting by correlation other parts of the organisation. In changes of this nature, there will be little or no tendency to alter the original pattern, or to transpose the parts. The bones of a limb might be shortened and flattened to any extent, becoming at the same time enveloped in thick membrane, so as to serve as a fin; or a webbed hand might have all its bones, or certain bones, lengthened to any extent, with the membrane connecting them increased, so as to serve as a wing; yet all these modifications would not tend to alter the framework of the bones or the relative connexion of the parts. If we suppose that an early progenitor--the archetype, as it may be called--of all mammals, birds and reptiles, had its limbs constructed on the existing general pattern, for whatever purpose they served, we can at once perceive the plain signification of the homologous construction of the limbs throughout the class. So with the mouths of insects, we have only to suppose that their common progenitor had an upper lip, mandibles, and two pairs of maxillae, these parts being perhaps very simple in form; and then natural selection will account for the infinite diversity in structure and function of the mouths of insects. Nevertheless, it is conceivable that the general pattern of an organ might become so much obscured as to be finally lost, by the reduction and ultimately by the complete abortion of certain parts, by the fusion of other parts, and by the doubling or multiplication of others, variations which we know to be within the limits of possibility. In the paddles of the gigantic extinct sea-lizards, and in the mouths of certain suctorial crustaceans, the general pattern seems thus to have become partially obscured. There is another and equally curious branch of our subject; namely, serial homologies, or the comparison of the different parts or organs in the same individual, and not of the same parts or organs in different members of the same class. Most physiologists believe that the bones of the skull are homologous--that is, correspond in number and in relative connexion--with the elemental parts of a certain number of vertebrae. The anterior and posterior limbs in all the higher vertebrate classes are plainly homologous. So it is with the wonderfully complex jaws and legs of crustaceans. It is familiar to almost every one, that in a flower the relative position of the sepals, petals, stamens, and pistils, as well as their intimate structure, are intelligible on the view that they consist of metamorphosed leaves, arranged in a spire. In monstrous plants, we often get direct evidence of the possibility of one organ being transformed into another; and we can actually see, during the early or embryonic stages of development in flowers, as well as in crustaceans and many other animals, that organs, which when mature become extremely different are at first exactly alike. How inexplicable are the cases of serial homologies on the ordinary view of creation! Why should the brain be enclosed in a box composed of such numerous and such extraordinarily shaped pieces of bone apparently representing vertebrae? As Owen has remarked, the benefit derived from the yielding of the separate pieces in the act of parturition by mammals, will by no means explain the same construction in the skulls of birds and reptiles. Why should similar bones have been created to form the wing and the leg of a bat, used as they are for such totally different purposes, namely flying and walking? Why should one crustacean, which has an extremely complex mouth formed of many parts, consequently always have fewer legs; or conversely, those with many legs have simpler mouths? Why should the sepals, petals, stamens, and pistils, in each flower, though fitted for such distinct purposes, be all constructed on the same pattern? On the theory of natural selection, we can, to a certain extent, answer these questions. We need not here consider how the bodies of some animals first became divided into a series of segments, or how they became divided into right and left sides, with corresponding organs, for such questions are almost beyond investigation. It is, however, probable that some serial structures are the result of cells multiplying by division, entailing the multiplication of the parts developed from such cells. It must suffice for our purpose to bear in mind that an indefinite repetition of the same part or organ is the common characteristic, as Owen has remarked, of all low or little specialised forms; therefore the unknown progenitor of the Vertebrata probably possessed many vertebrae; the unknown progenitor of the Articulata, many segments; and the unknown progenitor of flowering plants, many leaves arranged in one or more spires. We have also formerly seen that parts many times repeated are eminently liable to vary, not only in number, but in form. Consequently such parts, being already present in considerable numbers, and being highly variable, would naturally afford the materials for adaptation to the most different purposes; yet they would generally retain, through the force of inheritance, plain traces of their original or fundamental resemblance. They would retain this resemblance all the more, as the variations, which afforded the basis for their subsequent modification through natural selection, would tend from the first to be similar; the parts being at an early stage of growth alike, and being subjected to nearly the same conditions. Such parts, whether more or less modified, unless their common origin became wholly obscured, would be serially homologous. In the great class of molluscs, though the parts in distinct species can be shown to be homologous, only a few serial homologies; such as the valves of Chitons, can be indicated; that is, we are seldom enabled to say that one part is homologous with another part in the same individual. And we can understand this fact; for in molluscs, even in the lowest members of the class, we do not find nearly so much indefinite repetition of any one part as we find in the other great classes of the animal and vegetable kingdoms. But morphology is a much more complex subject than it at first appears, as has lately been well shown in a remarkable paper by Mr. E. Ray Lankester, who has drawn an important distinction between certain classes of cases which have all been equally ranked by naturalists as homologous. He proposes to call the structures which resemble each other in distinct animals, owing to their descent from a common progenitor with subsequent modification, "homogenous"; and the resemblances which cannot thus be accounted for, he proposes to call "homoplastic". For instance, he believes that the hearts of birds and mammals are as a whole homogenous--that is, have been derived from a common progenitor; but that the four cavities of the heart in the two classes are homoplastic--that is, have been independently developed. Mr. Lankester also adduces the close resemblance of the parts on the right and left sides of the body, and in the successive segments of the same individual animal; and here we have parts commonly called homologous which bear no relation to the descent of distinct species from a common progenitor. Homoplastic structures are the same with those which I have classed, though in a very imperfect manner, as analogous modifications or resemblances. Their formation may be attributed in part to distinct organisms, or to distinct parts of the same organism, having varied in an analogous manner; and in part to similar modifications, having been preserved for the same general purpose or function, of which many instances have been given. Naturalists frequently speak of the skull as formed of metamorphosed vertebrae; the jaws of crabs as metamorphosed legs; the stamens and pistils in flowers as metamorphosed leaves; but it would in most cases be more correct, as Professor Huxley has remarked, to speak of both skull and vertebrae, jaws and legs, etc., as having been metamorphosed, not one from the other, as they now exist, but from some common and simpler element. Most naturalists, however, use such language only in a metaphorical sense: they are far from meaning that during a long course of descent, primordial organs of any kind--vertebrae in the one case and legs in the other--have actually been converted into skulls or jaws. Yet so strong is the appearance of this having occurred that naturalists can hardly avoid employing language having this plain signification. According to the views here maintained, such language may be used literally; and the wonderful fact of the jaws, for instance, of a crab retaining numerous characters, which they probably would have retained through inheritance, if they had really been metamorphosed from true though extremely simple legs, is in part explained. DEVELOPMENT AND EMBRYOLOGY. This is one of the most important subjects in the whole round of natural history. The metamorphoses of insects, with which every one is familiar, are generally effected abruptly by a few stages; but the transformations are in reality numerous and gradual, though concealed. A certain ephemerous insect (Chloeon) during its development, moults, as shown by Sir J. Lubbock, above twenty times, and each time undergoes a certain amount of change; and in this case we see the act of metamorphosis performed in a primary and gradual manner. Many insects, and especially certain crustaceans, show us what wonderful changes of structure can be effected during development. Such changes, however, reach their acme in the so-called alternate generations of some of the lower animals. It is, for instance, an astonishing fact that a delicate branching coralline, studded with polypi, and attached to a submarine rock, should produce, first by budding and then by transverse division, a host of huge floating jelly-fishes; and that these should produce eggs, from which are hatched swimming animalcules, which attach themselves to rocks and become developed into branching corallines; and so on in an endless cycle. The belief in the essential identity of the process of alternate generation and of ordinary metamorphosis has been greatly strengthened by Wagner's discovery of the larva or maggot of a fly, namely the Cecidomyia, producing asexually other larvae, and these others, which finally are developed into mature males and females, propagating their kind in the ordinary manner by eggs. It may be worth notice that when Wagner's remarkable discovery was first announced, I was asked how was it possible to account for the larvae of this fly having acquired the power of a sexual reproduction. As long as the case remained unique no answer could be given. But already Grimm has shown that another fly, a Chironomus, reproduces itself in nearly the same manner, and he believes that this occurs frequently in the order. It is the pupa, and not the larva, of the Chironomus which has this power; and Grimm further shows that this case, to a certain extent, "unites that of the Cecidomyia with the parthenogenesis of the Coccidae;" the term parthenogenesis implying that the mature females of the Coccidae are capable of producing fertile eggs without the concourse of the male. Certain animals belonging to several classes are now known to have the power of ordinary reproduction at an unusually early age; and we have only to accelerate parthenogenetic reproduction by gradual steps to an earlier and earlier age--Chironomus showing us an almost exactly intermediate stage, viz., that of the pupa--and we can perhaps account for the marvellous case of the Cecidomyia. It has already been stated that various parts in the same individual, which are exactly alike during an early embryonic period, become widely different and serve for widely different purposes in the adult state. So again it has been shown that generally the embryos of the most distinct species belonging to the same class are closely similar, but become, when fully developed, widely dissimilar. A better proof of this latter fact cannot be given than the statement by Von Baer that "the embryos of mammalia, of birds, lizards and snakes, probably also of chelonia, are in the earliest states exceedingly like one another, both as a whole and in the mode of development of their parts; so much so, in fact, that we can often distinguish the embryos only by their size. In my possession are two little embryos in spirit, whose names I have omitted to attach, and at present I am quite unable to say to what class they belong. They may be lizards or small birds, or very young mammalia, so complete is the similarity in the mode of formation of the head and trunk in these animals. The extremities, however, are still absent in these embryos. But even if they had existed in the earliest stage of their development we should learn nothing, for the feet of lizards and mammals, the wings and feet of birds, no less than the hands and feet of man, all arise from the same fundamental form." The larvae of most crustaceans, at corresponding stages of development, closely resemble each other, however different the adults may become; and so it is with very many other animals. A trace of the law of embryonic resemblance occasionally lasts till a rather late age: thus birds of the same genus, and of allied genera, often resemble each other in their immature plumage; as we see in the spotted feathers in the young of the thrush group. In the cat tribe, most of the species when adult are striped or spotted in lines; and stripes or spots can be plainly distinguished in the whelp of the lion and the puma. We occasionally, though rarely, see something of the same kind in plants; thus the first leaves of the ulex or furze, and the first leaves of the phyllodineous acacias, are pinnate or divided like the ordinary leaves of the leguminosae. The points of structure, in which the embryos of widely different animals within the same class resemble each other, often have no direct relation to their conditions of existence. We cannot, for instance, suppose that in the embryos of the vertebrata the peculiar loop-like courses of the arteries near the branchial slits are related to similar conditions--in the young mammal which is nourished in the womb of its mother, in the egg of the bird which is hatched in a nest, and in the spawn of a frog under water. We have no more reason to believe in such a relation than we have to believe that the similar bones in the hand of a man, wing of a bat, and fin of a porpoise, are related to similar conditions of life. No one supposes that the stripes on the whelp of a lion, or the spots on the young blackbird, are of any use to these animals. The case, however, is different when an animal, during any part of its embryonic career, is active, and has to provide for itself. The period of activity may come on earlier or later in life; but whenever it comes on, the adaptation of the larva to its conditions of life is just as perfect and as beautiful as in the adult animal. In how important a manner this has acted, has recently been well shown by Sir J. Lubbock in his remarks on the close similarity of the larvae of some insects belonging to very different orders, and on the dissimilarity of the larvae of other insects within the same order, according to their habits of life. Owing to such adaptations the similarity of the larvae of allied animals is sometimes greatly obscured; especially when there is a division of labour during the different stages of development, as when the same larva has during one stage to search for food, and during another stage has to search for a place of attachment. Cases can even be given of the larvae of allied species, or groups of species, differing more from each other than do the adults. In most cases, however, the larvae, though active, still obey, more or less closely, the law of common embryonic resemblance. Cirripedes afford a good instance of this: even the illustrious Cuvier did not perceive that a barnacle was a crustacean: but a glance at the larva shows this in an unmistakable manner. So again the two main divisions of cirripedes, the pedunculated and sessile, though differing widely in external appearance, have larvae in all their stages barely distinguishable. The embryo in the course of development generally rises in organisation. I use this expression, though I am aware that it is hardly possible to define clearly what is meant by organisation being higher or lower. But no one probably will dispute that the butterfly is higher than the caterpillar. In some cases, however, the mature animal must be considered as lower in the scale than the larva, as with certain parasitic crustaceans. To refer once again to cirripedes: the larvae in the first stage have three pairs of locomotive organs, a simple single eye, and a probosciformed mouth, with which they feed largely, for they increase much in size. In the second stage, answering to the chrysalis stage of butterflies, they have six pairs of beautifully constructed natatory legs, a pair of magnificent compound eyes, and extremely complex antennae; but they have a closed and imperfect mouth, and cannot feed: their function at this stage is, to search out by their well-developed organs of sense, and to reach by their active powers of swimming, a proper place on which to become attached and to undergo their final metamorphosis. When this is completed they are fixed for life: their legs are now converted into prehensile organs; they again obtain a well-constructed mouth; but they have no antennae, and their two eyes are now reconverted into a minute, single, simple eye-spot. In this last and complete state, cirripedes may be considered as either more highly or more lowly organised than they were in the larval condition. But in some genera the larvae become developed into hermaphrodites having the ordinary structure, or into what I have called complemental males; and in the latter the development has assuredly been retrograde; for the male is a mere sack, which lives for a short time and is destitute of mouth, stomach, and every other organ of importance, excepting those for reproduction. We are so much accustomed to see a difference in structure between the embryo and the adult, that we are tempted to look at this difference as in some necessary manner contingent on growth. But there is no reason why, for instance, the wing of a bat, or the fin of a porpoise, should not have been sketched out with all their parts in proper proportion, as soon as any part became visible. In some whole groups of animals and in certain members of other groups this is the case, and the embryo does not at any period differ widely from the adult: thus Owen has remarked in regard to cuttle-fish, "there is no metamorphosis; the cephalopodic character is manifested long before the parts of the embryo are completed." Land-shells and fresh-water crustaceans are born having their proper forms, while the marine members of the same two great classes pass through considerable and often great changes during their development. Spiders, again, barely undergo any metamorphosis. The larvae of most insects pass through a worm-like stage, whether they are active and adapted to diversified habits, or are inactive from being placed in the midst of proper nutriment, or from being fed by their parents; but in some few cases, as in that of Aphis, if we look to the admirable drawings of the development of this insect, by Professor Huxley, we see hardly any trace of the vermiform stage. Sometimes it is only the earlier developmental stages which fail. Thus, Fritz Muller has made the remarkable discovery that certain shrimp-like crustaceans (allied to Penoeus) first appear under the simple nauplius-form, and after passing through two or more zoea-stages, and then through the mysis-stage, finally acquire their mature structure: now in the whole great malacostracan order, to which these crustaceans belong, no other member is as yet known to be first developed under the nauplius-form, though many appear as zoeas; nevertheless Muller assigns reasons for his belief, that if there had been no suppression of development, all these crustaceans would have appeared as nauplii. How, then, can we explain these several facts in embryology--namely, the very general, though not universal, difference in structure between the embryo and the adult; the various parts in the same individual embryo, which ultimately become very unlike, and serve for diverse purposes, being at an early period of growth alike; the common, but not invariable, resemblance between the embryos or larvae of the most distinct species in the same class; the embryo often retaining, while within the egg or womb, structures which are of no service to it, either at that or at a later period of life; on the other hand, larvae which have to provide for their own wants, being perfectly adapted to the surrounding conditions; and lastly, the fact of certain larvae standing higher in the scale of organisation than the mature animal into which they are developed? I believe that all these facts can be explained as follows. It is commonly assumed, perhaps from monstrosities affecting the embryo at a very early period, that slight variations or individual differences necessarily appear at an equally early period. We have little evidence on this head, but what we have certainly points the other way; for it is notorious that breeders of cattle, horses and various fancy animals, cannot positively tell, until some time after birth, what will be the merits and demerits of their young animals. We see this plainly in our own children; we cannot tell whether a child will be tall or short, or what its precise features will be. The question is not, at what period of life any variation may have been caused, but at what period the effects are displayed. The cause may have acted, and I believe often has acted, on one or both parents before the act of generation. It deserves notice that it is of no importance to a very young animal, as long as it is nourished and protected by its parent, whether most of its characters are acquired a little earlier or later in life. It would not signify, for instance, to a bird which obtained its food by having a much-curved beak whether or not while young it possessed a beak of this shape, as long as it was fed by its parents. I have stated in the first chapter, that at whatever age any variation first appears in the parent, it tends to reappear at a corresponding age in the offspring. Certain variations can only appear at corresponding ages; for instance, peculiarities in the caterpillar, cocoon, or imago states of the silk-moth; or, again, in the full-grown horns of cattle. But variations which, for all that we can see might have appeared either earlier or later in life, likewise tend to reappear at a corresponding age in the offspring and parent. I am far from meaning that this is invariably the case, and I could give several exceptional cases of variations (taking the word in the largest sense) which have supervened at an earlier age in the child than in the parent. These two principles, namely, that slight variations generally appear at a not very early period of life, and are inherited at a corresponding not early period, explain, as I believe, all the above specified leading facts in embryology. But first let us look to a few analogous cases in our domestic varieties. Some authors who have written on Dogs maintain that the greyhound and bull-dog, though so different, are really closely allied varieties, descended from the same wild stock, hence I was curious to see how far their puppies differed from each other. I was told by breeders that they differed just as much as their parents, and this, judging by the eye, seemed almost to be the case; but on actually measuring the old dogs and their six-days-old puppies, I found that the puppies had not acquired nearly their full amount of proportional difference. So, again, I was told that the foals of cart and race-horses--breeds which have been almost wholly formed by selection under domestication--differed as much as the full-grown animals; but having had careful measurements made of the dams and of three-days-old colts of race and heavy cart-horses, I find that this is by no means the case. As we have conclusive evidence that the breeds of the Pigeon are descended from a single wild species, I compared the young pigeons within twelve hours after being hatched. I carefully measured the proportions (but will not here give the details) of the beak, width of mouth, length of nostril and of eyelid, size of feet and length of leg, in the wild parent species, in pouters, fantails, runts, barbs, dragons, carriers, and tumblers. Now, some of these birds, when mature, differ in so extraordinary a manner in the length and form of beak, and in other characters, that they would certainly have been ranked as distinct genera if found in a state of nature. But when the nestling birds of these several breeds were placed in a row, though most of them could just be distinguished, the proportional differences in the above specified points were incomparably less than in the full-grown birds. Some characteristic points of difference--for instance, that of the width of mouth--could hardly be detected in the young. But there was one remarkable exception to this rule, for the young of the short-faced tumbler differed from the young of the wild rock-pigeon, and of the other breeds, in almost exactly the same proportions as in the adult stage. These facts are explained by the above two principles. Fanciers select their dogs, horses, pigeons, etc., for breeding, when nearly grown up. They are indifferent whether the desired qualities are acquired earlier or later in life, if the full-grown animal possesses them. And the cases just given, more especially that of the pigeons, show that the characteristic differences which have been accumulated by man's selection, and which give value to his breeds, do not generally appear at a very early period of life, and are inherited at a corresponding not early period. But the case of the short-faced tumbler, which when twelve hours old possessed its proper characters, proves that this is not the universal rule; for here the characteristic differences must either have appeared at an earlier period than usual, or, if not so, the differences must have been inherited, not at a corresponding, but at an earlier age. Now, let us apply these two principles to species in a state of nature. Let us take a group of birds, descended from some ancient form and modified through natural selection for different habits. Then, from the many slight successive variations having supervened in the several species at a not early age, and having been inherited at a corresponding age, the young will have been but little modified, and they will still resemble each other much more closely than do the adults, just as we have seen with the breeds of the pigeon. We may extend this view to widely distinct structures and to whole classes. The fore-limbs, for instance, which once served as legs to a remote progenitor, may have become, through a long course of modification, adapted in one descendant to act as hands, in another as paddles, in another as wings; but on the above two principles the fore-limbs will not have been much modified in the embryos of these several forms; although in each form the fore-limb will differ greatly in the adult state. Whatever influence long continued use or disuse may have had in modifying the limbs or other parts of any species, this will chiefly or solely have affected it when nearly mature, when it was compelled to use its full powers to gain its own living; and the effects thus produced will have been transmitted to the offspring at a corresponding nearly mature age. Thus the young will not be modified, or will be modified only in a slight degree, through the effects of the increased use or disuse of parts. With some animals the successive variations may have supervened at a very early period of life, or the steps may have been inherited at an earlier age than that at which they first occurred. In either of these cases the young or embryo will closely resemble the mature parent-form, as we have seen with the short-faced tumbler. And this is the rule of development in certain whole groups, or in certain sub-groups alone, as with cuttle-fish, land-shells, fresh-water crustaceans, spiders, and some members of the great class of insects. With respect to the final cause of the young in such groups not passing through any metamorphosis, we can see that this would follow from the following contingencies: namely, from the young having to provide at a very early age for their own wants, and from their following the same habits of life with their parents; for in this case it would be indispensable for their existence that they should be modified in the same manner as their parents. Again, with respect to the singular fact that many terrestrial and fresh-water animals do not undergo any metamorphosis, while marine members of the same groups pass through various transformations, Fritz Muller has suggested that the process of slowly modifying and adapting an animal to live on the land or in fresh water, instead of in the sea, would be greatly simplified by its not passing through any larval stage; for it is not probable that places well adapted for both the larval and mature stages, under such new and greatly changed habits of life, would commonly be found unoccupied or ill-occupied by other organisms. In this case the gradual acquirement at an earlier and earlier age of the adult structure would be favoured by natural selection; and all traces of former metamorphoses would finally be lost. If, on the other hand, it profited the young of an animal to follow habits of life slightly different from those of the parent-form, and consequently to be constructed on a slightly different plan, or if it profited a larva already different from its parent to change still further, then, on the principle of inheritance at corresponding ages, the young or the larvae might be rendered by natural selection more and more different from their parents to any conceivable extent. Differences in the larva might, also, become correlated with successive stages of its development; so that the larva, in the first stage, might come to differ greatly from the larva in the second stage, as is the case with many animals. The adult might also become fitted for sites or habits, in which organs of locomotion or of the senses, etc., would be useless; and in this case the metamorphosis would be retrograde. From the remarks just made we can see how by changes of structure in the young, in conformity with changed habits of life, together with inheritance at corresponding ages, animals might come to pass through stages of development, perfectly distinct from the primordial condition of their adult progenitors. Most of our best authorities are now convinced that the various larval and pupal stages of insects have thus been acquired through adaptation, and not through inheritance from some ancient form. The curious case of Sitaris--a beetle which passes through certain unusual stages of development--will illustrate how this might occur. The first larval form is described by M. Fabre, as an active, minute insect, furnished with six legs, two long antennae, and four eyes. These larvae are hatched in the nests of bees; and when the male bees emerge from their burrows, in the spring, which they do before the females, the larvae spring on them, and afterwards crawl on to the females while paired with the males. As soon as the female bee deposits her eggs on the surface of the honey stored in the cells, the larvae of the Sitaris leap on the eggs and devour them. Afterwards they undergo a complete change; their eyes disappear; their legs and antennae become rudimentary, and they feed on honey; so that they now more closely resemble the ordinary larvae of insects; ultimately they undergo a further transformation, and finally emerge as the perfect beetle. Now, if an insect, undergoing transformations like those of the Sitaris, were to become the progenitor of a whole new class of insects, the course of development of the new class would be widely different from that of our existing insects; and the first larval stage certainly would not represent the former condition of any adult and ancient form. On the other hand it is highly probable that with many animals the embryonic or larval stages show us, more or less completely, the condition of the progenitor of the whole group in its adult state. In the great class of the Crustacea, forms wonderfully distinct from each other, namely, suctorial parasites, cirripedes, entomostraca, and even the malacostraca, appear at first as larvae under the nauplius-form; and as these larvae live and feed in the open sea, and are not adapted for any peculiar habits of life, and from other reasons assigned by Fritz Muller, it is probable that at some very remote period an independent adult animal, resembling the Nauplius, existed, and subsequently produced, along several divergent lines of descent, the above-named great Crustacean groups. So again, it is probable, from what we know of the embryos of mammals, birds, fishes and reptiles, that these animals are the modified descendants of some ancient progenitor, which was furnished in its adult state with branchiae, a swim-bladder, four fin-like limbs, and a long tail, all fitted for an aquatic life. As all the organic beings, extinct and recent, which have ever lived, can be arranged within a few great classes; and as all within each class have, according to our theory, been connected together by fine gradations, the best, and, if our collections were nearly perfect, the only possible arrangement, would be genealogical; descent being the hidden bond of connexion which naturalists have been seeking under the term of the Natural System. On this view we can understand how it is that, in the eyes of most naturalists, the structure of the embryo is even more important for classification than that of the adult. In two or more groups of animals, however much they may differ from each other in structure and habits in their adult condition, if they pass through closely similar embryonic stages, we may feel assured that they are all descended from one parent-form, and are therefore closely related. Thus, community in embryonic structure reveals community of descent; but dissimilarity in embryonic development does not prove discommunity of descent, for in one of two groups the developmental stages may have been suppressed, or may have been so greatly modified through adaptation to new habits of life as to be no longer recognisable. Even in groups, in which the adults have been modified to an extreme degree, community of origin is often revealed by the structure of the larvae; we have seen, for instance, that cirripedes, though externally so like shell-fish, are at once known by their larvae to belong to the great class of crustaceans. As the embryo often shows us more or less plainly the structure of the less modified and ancient progenitor of the group, we can see why ancient and extinct forms so often resemble in their adult state the embryos of existing species of the same class. Agassiz believes this to be a universal law of nature; and we may hope hereafter to see the law proved true. It can, however, be proved true only in those cases in which the ancient state of the progenitor of the group has not been wholly obliterated, either by successive variations having supervened at a very early period of growth, or by such variations having been inherited at an earlier age than that at which they first appeared. It should also be borne in mind, that the law may be true, but yet, owing to the geological record not extending far enough back in time, may remain for a long period, or for ever, incapable of demonstration. The law will not strictly hold good in those cases in which an ancient form became adapted in its larval state to some special line of life, and transmitted the same larval state to a whole group of descendants; for such larval state will not resemble any still more ancient form in its adult state. Thus, as it seems to me, the leading facts in embryology, which are second to none in importance, are explained on the principle of variations in the many descendants from some one ancient progenitor, having appeared at a not very early period of life, and having been inherited at a corresponding period. Embryology rises greatly in interest, when we look at the embryo as a picture, more or less obscured, of the progenitor, either in its adult or larval state, of all the members of the same great class. RUDIMENTARY, ATROPHIED, AND ABORTED ORGANS. Organs or parts in this strange condition, bearing the plain stamp of inutility, are extremely common, or even general, throughout nature. It would be impossible to name one of the higher animals in which some part or other is not in a rudimentary condition. In the mammalia, for instance, the males possess rudimentary mammae; in snakes one lobe of the lungs is rudimentary; in birds the "bastard-wing" may safely be considered as a rudimentary digit, and in some species the whole wing is so far rudimentary that it cannot be used for flight. What can be more curious than the presence of teeth in foetal whales, which when grown up have not a tooth in their heads; or the teeth, which never cut through the gums, in the upper jaws of unborn calves? Rudimentary organs plainly declare their origin and meaning in various ways. There are beetles belonging to closely allied species, or even to the same identical species, which have either full-sized and perfect wings, or mere rudiments of membrane, which not rarely lie under wing-covers firmly soldered together; and in these cases it is impossible to doubt, that the rudiments represent wings. Rudimentary organs sometimes retain their potentiality: this occasionally occurs with the mammae of male mammals, which have been known to become well developed and to secrete milk. So again in the udders of the genus Bos, there are normally four developed and two rudimentary teats; but the latter in our domestic cows sometimes become well developed and yield milk. In regard to plants, the petals are sometimes rudimentary, and sometimes well developed in the individuals of the same species. In certain plants having separated sexes Kolreuter found that by crossing a species, in which the male flowers included a rudiment of a pistil, with an hermaphrodite species, having of course a well-developed pistil, the rudiment in the hybrid offspring was much increased in size; and this clearly shows that the rudimentary and perfect pistils are essentially alike in nature. An animal may possess various parts in a perfect state, and yet they may in one sense be rudimentary, for they are useless: thus the tadpole of the common salamander or water-newt, as Mr. G.H. Lewes remarks, "has gills, and passes its existence in the water; but the Salamandra atra, which lives high up among the mountains, brings forth its young full-formed. This animal never lives in the water. Yet if we open a gravid female, we find tadpoles inside her with exquisitely feathered gills; and when placed in water they swim about like the tadpoles of the water-newt. Obviously this aquatic organisation has no reference to the future life of the animal, nor has it any adaptation to its embryonic condition; it has solely reference to ancestral adaptations, it repeats a phase in the development of its progenitors." An organ, serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose, and remain perfectly efficient for the other. Thus, in plants, the office of the pistil is to allow the pollen-tubes to reach the ovules within the ovarium. The pistil consists of a stigma supported on the style; but in some Compositae, the male florets, which of course cannot be fecundated, have a rudimentary pistil, for it is not crowned with a stigma; but the style remains well developed and is clothed in the usual manner with hairs, which serve to brush the pollen out of the surrounding and conjoined anthers. Again, an organ may become rudimentary for its proper purpose, and be used for a distinct one: in certain fishes the swim-bladder seems to be rudimentary for its proper function of giving buoyancy, but has become converted into a nascent breathing organ or lung. Many similar instances could be given. Useful organs, however little they may be developed, unless we have reason to suppose that they were formerly more highly developed, ought not to be considered as rudimentary. They may be in a nascent condition, and in progress towards further development. Rudimentary organs, on the other hand, are either quite useless, such as teeth which never cut through the gums, or almost useless, such as the wings of an ostrich, which serve merely as sails. As organs in this condition would formerly, when still less developed, have been of even less use than at present, they cannot formerly have been produced through variation and natural selection, which acts solely by the preservation of useful modifications. They have been partially retained by the power of inheritance, and relate to a former state of things. It is, however, often difficult to distinguish between rudimentary and nascent organs; for we can judge only by analogy whether a part is capable of further development, in which case alone it deserves to be called nascent. Organs in this condition will always be somewhat rare; for beings thus provided will commonly have been supplanted by their successors with the same organ in a more perfect state, and consequently will have become long ago extinct. The wing of the penguin is of high service, acting as a fin; it may, therefore, represent the nascent state of the wing: not that I believe this to be the case; it is more probably a reduced organ, modified for a new function: the wing of the Apteryx, on the other hand, is quite useless, and is truly rudimentary. Owen considers the simple filamentary limbs of the Lepidosiren as the "beginnings of organs which attain full functional development in higher vertebrates;" but, according to the view lately advocated by Dr. Gunther, they are probably remnants, consisting of the persistent axis of a fin, with the lateral rays or branches aborted. The mammary glands of the Ornithorhynchus may be considered, in comparison with the udders of a cow, as in a nascent condition. The ovigerous frena of certain cirripedes, which have ceased to give attachment to the ova and are feebly developed, are nascent branchiae. Rudimentary organs in the individuals of the same species are very liable to vary in the degree of their development and in other respects. In closely allied species, also, the extent to which the same organ has been reduced occasionally differs much. This latter fact is well exemplified in the state of the wings of female moths belonging to the same family. Rudimentary organs may be utterly aborted; and this implies, that in certain animals or plants, parts are entirely absent which analogy would lead us to expect to find in them, and which are occasionally found in monstrous individuals. Thus in most of the Scrophulariaceae the fifth stamen is utterly aborted; yet we may conclude that a fifth stamen once existed, for a rudiment of it is found in many species of the family, and this rudiment occasionally becomes perfectly developed, as may sometimes be seen in the common snap-dragon. In tracing the homologies of any part in different members of the same class, nothing is more common, or, in order fully to understand the relations of the parts, more useful than the discovery of rudiments. This is well shown in the drawings given by Owen of the leg bones of the horse, ox, and rhinoceros. It is an important fact that rudimentary organs, such as teeth in the upper jaws of whales and ruminants, can often be detected in the embryo, but afterwards wholly disappear. It is also, I believe, a universal rule, that a rudimentary part is of greater size in the embryo relatively to the adjoining parts, than in the adult; so that the organ at this early age is less rudimentary, or even cannot be said to be in any degree rudimentary. Hence rudimentary organs in the adult are often said to have retained their embryonic condition. I have now given the leading facts with respect to rudimentary organs. In reflecting on them, every one must be struck with astonishment; for the same reasoning power which tells us that most parts and organs are exquisitely adapted for certain purposes, tells us with equal plainness that these rudimentary or atrophied organs are imperfect and useless. In works on natural history, rudimentary organs are generally said to have been created "for the sake of symmetry," or in order "to complete the scheme of nature." But this is not an explanation, merely a restatement of the fact. Nor is it consistent with itself: thus the boa-constrictor has rudiments of hind limbs and of a pelvis, and if it be said that these bones have been retained "to complete the scheme of nature," why, as Professor Weismann asks, have they not been retained by other snakes, which do not possess even a vestige of these same bones? What would be thought of an astronomer who maintained that the satellites revolve in elliptic courses round their planets "for the sake of symmetry," because the planets thus revolve round the sun? An eminent physiologist accounts for the presence of rudimentary organs, by supposing that they serve to excrete matter in excess, or matter injurious to the system; but can we suppose that the minute papilla, which often represents the pistil in male flowers, and which is formed of mere cellular tissue, can thus act? Can we suppose that rudimentary teeth, which are subsequently absorbed, are beneficial to the rapidly growing embryonic calf by removing matter so precious as phosphate of lime? When a man's fingers have been amputated, imperfect nails have been known to appear on the stumps, and I could as soon believe that these vestiges of nails are developed in order to excrete horny matter, as that the rudimentary nails on the fin of the manatee have been developed for this same purpose. On the view of descent with modification, the origin of rudimentary organs is comparatively simple; and we can understand to a large extent the laws governing their imperfect development. We have plenty of cases of rudimentary organs in our domestic productions, as the stump of a tail in tailless breeds, the vestige of an ear in earless breeds of sheep--the reappearance of minute dangling horns in hornless breeds of cattle, more especially, according to Youatt, in young animals--and the state of the whole flower in the cauliflower. We often see rudiments of various parts in monsters; but I doubt whether any of these cases throw light on the origin of rudimentary organs in a state of nature, further than by showing that rudiments can be produced; for the balance of evidence clearly indicates that species under nature do not undergo great and abrupt changes. But we learn from the study of our domestic productions that the disuse of parts leads to their reduced size; and that the result is inherited. It appears probable that disuse has been the main agent in rendering organs rudimentary. It would at first lead by slow steps to the more and more complete reduction of a part, until at last it became rudimentary--as in the case of the eyes of animals inhabiting dark caverns, and of the wings of birds inhabiting oceanic islands, which have seldom been forced by beasts of prey to take flight, and have ultimately lost the power of flying. Again, an organ, useful under certain conditions, might become injurious under others, as with the wings of beetles living on small and exposed islands; and in this case natural selection will have aided in reducing the organ, until it was rendered harmless and rudimentary. Any change in structure and function, which can be effected by small stages, is within the power of natural selection; so that an organ rendered, through changed habits of life, useless or injurious for one purpose, might be modified and used for another purpose. An organ might, also, be retained for one alone of its former functions. Organs, originally formed by the aid of natural selection, when rendered useless may well be variable, for their variations can no longer be checked by natural selection. All this agrees well with what we see under nature. Moreover, at whatever period of life either disuse or selection reduces an organ, and this will generally be when the being has come to maturity and to exert its full powers of action, the principle of inheritance at corresponding ages will tend to reproduce the organ in its reduced state at the same mature age, but will seldom affect it in the embryo. Thus we can understand the greater size of rudimentary organs in the embryo relatively to the adjoining parts, and their lesser relative size in the adult. If, for instance, the digit of an adult animal was used less and less during many generations, owing to some change of habits, or if an organ or gland was less and less functionally exercised, we may infer that it would become reduced in size in the adult descendants of this animal, but would retain nearly its original standard of development in the embryo. There remains, however, this difficulty. After an organ has ceased being used, and has become in consequence much reduced, how can it be still further reduced in size until the merest vestige is left; and how can it be finally quite obliterated? It is scarcely possible that disuse can go on producing any further effect after the organ has once been rendered functionless. Some additional explanation is here requisite which I cannot give. If, for instance, it could be proved that every part of the organisation tends to vary in a greater degree towards diminution than toward augmentation of size, then we should be able to understand how an organ which has become useless would be rendered, independently of the effects of disuse, rudimentary and would at last be wholly suppressed; for the variations towards diminished size would no longer be checked by natural selection. The principle of the economy of growth, explained in a former chapter, by which the materials forming any part, if not useful to the possessor, are saved as far as is possible, will perhaps come into play in rendering a useless part rudimentary. But this principle will almost necessarily be confined to the earlier stages of the process of reduction; for we cannot suppose that a minute papilla, for instance, representing in a male flower the pistil of the female flower, and formed merely of cellular tissue, could be further reduced or absorbed for the sake of economising nutriment. Finally, as rudimentary organs, by whatever steps they may have been degraded into their present useless condition, are the record of a former state of things, and have been retained solely through the power of inheritance--we can understand, on the genealogical view of classification, how it is that systematists, in placing organisms in their proper places in the natural system, have often found rudimentary parts as useful as, or even sometimes more useful than, parts of high physiological importance. Rudimentary organs may be compared with the letters in a word, still retained in the spelling, but become useless in the pronunciation, but which serve as a clue for its derivation. On the view of descent with modification, we may conclude that the existence of organs in a rudimentary, imperfect, and useless condition, or quite aborted, far from presenting a strange difficulty, as they assuredly do on the old doctrine of creation, might even have been anticipated in accordance with the views here explained. SUMMARY. In this chapter I have attempted to show that the arrangement of all organic beings throughout all time in groups under groups--that the nature of the relationships by which all living and extinct organisms are united by complex, radiating, and circuitous lines of affinities into a few grand classes--the rules followed and the difficulties encountered by naturalists in their classifications--the value set upon characters, if constant and prevalent, whether of high or of the most trifling importance, or, as with rudimentary organs of no importance--the wide opposition in value between analogical or adaptive characters, and characters of true affinity; and other such rules--all naturally follow if we admit the common parentage of allied forms, together with their modification through variation and natural selection, with the contingencies of extinction and divergence of character. In considering this view of classification, it should be borne in mind that the element of descent has been universally used in ranking together the sexes, ages, dimorphic forms, and acknowledged varieties of the same species, however much they may differ from each other in structure. If we extend the use of this element of descent--the one certainly known cause of similarity in organic beings--we shall understand what is meant by the Natural System: it is genealogical in its attempted arrangement, with the grades of acquired difference marked by the terms, varieties, species, genera, families, orders, and classes. On this same view of descent with modification, most of the great facts in Morphology become intelligible--whether we look to the same pattern displayed by the different species of the same class in their homologous organs, to whatever purpose applied, or to the serial and lateral homologies in each individual animal and plant. On the principle of successive slight variations, not necessarily or generally supervening at a very early period of life, and being inherited at a corresponding period, we can understand the leading facts in embryology; namely, the close resemblance in the individual embryo of the parts which are homologous, and which when matured become widely different in structure and function; and the resemblance of the homologous parts or organs in allied though distinct species, though fitted in the adult state for habits as different as is possible. Larvae are active embryos, which have become specially modified in a greater or less degree in relation to their habits of life, with their modifications inherited at a corresponding early age. On these same principles, and bearing in mind that when organs are reduced in size, either from disuse or through natural selection, it will generally be at that period of life when the being has to provide for its own wants, and bearing in mind how strong is the force of inheritance--the occurrence of rudimentary organs might even have been anticipated. The importance of embryological characters and of rudimentary organs in classification is intelligible, on the view that a natural arrangement must be genealogical. Finally, the several classes of facts which have been considered in this chapter, seem to me to proclaim so plainly, that the innumerable species, genera and families, with which this world is peopled, are all descended, each within its own class or group, from common parents, and have all been modified in the course of descent, that I should without hesitation adopt this view, even if it were unsupported by other facts or arguments. CHAPTER XV. RECAPITULATION AND CONCLUSION. Recapitulation of the objections to the theory of Natural Selection--Recapitulation of the general and special circumstances in its favour--Causes of the general belief in the immutability of species--How far the theory of Natural Selection may be extended--Effects of its adoption on the study of Natural History--Concluding remarks. As this whole volume is one long argument, it may be convenient to the reader to have the leading facts and inferences briefly recapitulated. That many and serious objections may be advanced against the theory of descent with modification through variation and natural selection, I do not deny. I have endeavoured to give to them their full force. Nothing at first can appear more difficult to believe than that the more complex organs and instincts have been perfected, not by means superior to, though analogous with, human reason, but by the accumulation of innumerable slight variations, each good for the individual possessor. Nevertheless, this difficulty, though appearing to our imagination insuperably great, cannot be considered real if we admit the following propositions, namely, that all parts of the organisation and instincts offer, at least individual differences--that there is a struggle for existence leading to the preservation of profitable deviations of structure or instinct--and, lastly, that gradations in the state of perfection of each organ may have existed, each good of its kind. The truth of these propositions cannot, I think, be disputed. It is, no doubt, extremely difficult even to conjecture by what gradations many structures have been perfected, more especially among broken and failing groups of organic beings, which have suffered much extinction; but we see so many strange gradations in nature, that we ought to be extremely cautious in saying that any organ or instinct, or any whole structure, could not have arrived at its present state by many graduated steps. There are, it must be admitted, cases of special difficulty opposed to the theory of natural selection; and one of the most curious of these is the existence in the same community of two or three defined castes of workers or sterile female ants; but I have attempted to show how these difficulties can be mastered. With respect to the almost universal sterility of species when first crossed, which forms so remarkable a contrast with the almost universal fertility of varieties when crossed, I must refer the reader to the recapitulation of the facts given at the end of the ninth chapter, which seem to me conclusively to show that this sterility is no more a special endowment than is the incapacity of two distinct kinds of trees to be grafted together; but that it is incidental on differences confined to the reproductive systems of the intercrossed species. We see the truth of this conclusion in the vast difference in the results of crossing the same two species reciprocally--that is, when one species is first used as the father and then as the mother. Analogy from the consideration of dimorphic and trimorphic plants clearly leads to the same conclusion, for when the forms are illegitimately united, they yield few or no seed, and their offspring are more or less sterile; and these forms belong to the same undoubted species, and differ from each other in no respect except in their reproductive organs and functions. Although the fertility of varieties when intercrossed, and of their mongrel offspring, has been asserted by so many authors to be universal, this cannot be considered as quite correct after the facts given on the high authority of Gartner and Kolreuter. Most of the varieties which have been experimented on have been produced under domestication; and as domestication (I do not mean mere confinement) almost certainly tends to eliminate that sterility which, judging from analogy, would have affected the parent-species if intercrossed, we ought not to expect that domestication would likewise induce sterility in their modified descendants when crossed. This elimination of sterility apparently follows from the same cause which allows our domestic animals to breed freely under diversified circumstances; and this again apparently follows from their having been gradually accustomed to frequent changes in their conditions of life. A double and parallel series of facts seems to throw much light on the sterility of species, when first crossed, and of their hybrid offspring. On the one side, there is good reason to believe that slight changes in the conditions of life give vigour and fertility to all organic beings. We know also that a cross between the distinct individuals of the same variety, and between distinct varieties, increases the number of their offspring, and certainly gives to them increased size and vigour. This is chiefly owing to the forms which are crossed having been exposed to somewhat different conditions of life; for I have ascertained by a labourious series of experiments that if all the individuals of the same variety be subjected during several generations to the same conditions, the good derived from crossing is often much diminished or wholly disappears. This is one side of the case. On the other side, we know that species which have long been exposed to nearly uniform conditions, when they are subjected under confinement to new and greatly changed conditions, either perish, or if they survive, are rendered sterile, though retaining perfect health. This does not occur, or only in a very slight degree, with our domesticated productions, which have long been exposed to fluctuating conditions. Hence when we find that hybrids produced by a cross between two distinct species are few in number, owing to their perishing soon after conception or at a very early age, or if surviving that they are rendered more or less sterile, it seems highly probable that this result is due to their having been in fact subjected to a great change in their conditions of life, from being compounded of two distinct organisations. He who will explain in a definite manner why, for instance, an elephant or a fox will not breed under confinement in its native country, whilst the domestic pig or dog will breed freely under the most diversified conditions, will at the same time be able to give a definite answer to the question why two distinct species, when crossed, as well as their hybrid offspring, are generally rendered more or less sterile, while two domesticated varieties when crossed and their mongrel offspring are perfectly fertile. Turning to geographical distribution, the difficulties encountered on the theory of descent with modification are serious enough. All the individuals of the same species, and all the species of the same genus, or even higher group, are descended from common parents; and therefore, in however distant and isolated parts of the world they may now be found, they must in the course of successive generations have travelled from some one point to all the others. We are often wholly unable even to conjecture how this could have been effected. Yet, as we have reason to believe that some species have retained the same specific form for very long periods of time, immensely long as measured by years, too much stress ought not to be laid on the occasional wide diffusion of the same species; for during very long periods there will always have been a good chance for wide migration by many means. A broken or interrupted range may often be accounted for by the extinction of the species in the intermediate regions. It cannot be denied that we are as yet very ignorant as to the full extent of the various climatical and geographical changes which have affected the earth during modern periods; and such changes will often have facilitated migration. As an example, I have attempted to show how potent has been the influence of the Glacial period on the distribution of the same and of allied species throughout the world. We are as yet profoundly ignorant of the many occasional means of transport. With respect to distinct species of the same genus, inhabiting distant and isolated regions, as the process of modification has necessarily been slow, all the means of migration will have been possible during a very long period; and consequently the difficulty of the wide diffusion of the species of the same genus is in some degree lessened. As according to the theory of natural selection an interminable number of intermediate forms must have existed, linking together all the species in each group by gradations as fine as our existing varieties, it may be asked, Why do we not see these linking forms all around us? Why are not all organic beings blended together in an inextricable chaos? With respect to existing forms, we should remember that we have no right to expect (excepting in rare cases) to discover DIRECTLY connecting links between them, but only between each and some extinct and supplanted form. Even on a wide area, which has during a long period remained continuous, and of which the climatic and other conditions of life change insensibly in proceeding from a district occupied by one species into another district occupied by a closely allied species, we have no just right to expect often to find intermediate varieties in the intermediate zones. For we have reason to believe that only a few species of a genus ever undergo change; the other species becoming utterly extinct and leaving no modified progeny. Of the species which do change, only a few within the same country change at the same time; and all modifications are slowly effected. I have also shown that the intermediate varieties which probably at first existed in the intermediate zones, would be liable to be supplanted by the allied forms on either hand; for the latter, from existing in greater numbers, would generally be modified and improved at a quicker rate than the intermediate varieties, which existed in lesser numbers; so that the intermediate varieties would, in the long run, be supplanted and exterminated. On this doctrine of the extermination of an infinitude of connecting links, between the living and extinct inhabitants of the world, and at each successive period between the extinct and still older species, why is not every geological formation charged with such links? Why does not every collection of fossil remains afford plain evidence of the gradation and mutation of the forms of life? Although geological research has undoubtedly revealed the former existence of many links, bringing numerous forms of life much closer together, it does not yield the infinitely many fine gradations between past and present species required on the theory, and this is the most obvious of the many objections which may be urged against it. Why, again, do whole groups of allied species appear, though this appearance is often false, to have come in suddenly on the successive geological stages? Although we now know that organic beings appeared on this globe, at a period incalculably remote, long before the lowest bed of the Cambrian system was deposited, why do we not find beneath this system great piles of strata stored with the remains of the progenitors of the Cambrian fossils? For on the theory, such strata must somewhere have been deposited at these ancient and utterly unknown epochs of the world's history. I can answer these questions and objections only on the supposition that the geological record is far more imperfect than most geologists believe. The number of specimens in all our museums is absolutely as nothing compared with the countless generations of countless species which have certainly existed. The parent form of any two or more species would not be in all its characters directly intermediate between its modified offspring, any more than the rock-pigeon is directly intermediate in crop and tail between its descendants, the pouter and fantail pigeons. We should not be able to recognise a species as the parent of another and modified species, if we were to examine the two ever so closely, unless we possessed most of the intermediate links; and owing to the imperfection of the geological record, we have no just right to expect to find so many links. If two or three, or even more linking forms were discovered, they would simply be ranked by many naturalists as so many new species, more especially if found in different geological substages, let their differences be ever so slight. Numerous existing doubtful forms could be named which are probably varieties; but who will pretend that in future ages so many fossil links will be discovered, that naturalists will be able to decide whether or not these doubtful forms ought to be called varieties? Only a small portion of the world has been geologically explored. Only organic beings of certain classes can be preserved in a fossil condition, at least in any great number. Many species when once formed never undergo any further change but become extinct without leaving modified descendants; and the periods during which species have undergone modification, though long as measured by years, have probably been short in comparison with the periods during which they retained the same form. It is the dominant and widely ranging species which vary most frequently and vary most, and varieties are often at first local--both causes rendering the discovery of intermediate links in any one formation less likely. Local varieties will not spread into other and distant regions until they are considerably modified and improved; and when they have spread, and are discovered in a geological formation, they appear as if suddenly created there, and will be simply classed as new species. Most formations have been intermittent in their accumulation; and their duration has probably been shorter than the average duration of specific forms. Successive formations are in most cases separated from each other by blank intervals of time of great length, for fossiliferous formations thick enough to resist future degradation can, as a general rule, be accumulated only where much sediment is deposited on the subsiding bed of the sea. During the alternate periods of elevation and of stationary level the record will generally be blank. During these latter periods there will probably be more variability in the forms of life; during periods of subsidence, more extinction. With respect to the absence of strata rich in fossils beneath the Cambrian formation, I can recur only to the hypothesis given in the tenth chapter; namely, that though our continents and oceans have endured for an enormous period in nearly their present relative positions, we have no reason to assume that this has always been the case; consequently formations much older than any now known may lie buried beneath the great oceans. With respect to the lapse of time not having been sufficient since our planet was consolidated for the assumed amount of organic change, and this objection, as urged by Sir William Thompson, is probably one of the gravest as yet advanced, I can only say, firstly, that we do not know at what rate species change, as measured by years, and secondly, that many philosophers are not as yet willing to admit that we know enough of the constitution of the universe and of the interior of our globe to speculate with safety on its past duration. That the geological record is imperfect all will admit; but that it is imperfect to the degree required by our theory, few will be inclined to admit. If we look to long enough intervals of time, geology plainly declares that species have all changed; and they have changed in the manner required by the theory, for they have changed slowly and in a graduated manner. We clearly see this in the fossil remains from consecutive formations invariably being much more closely related to each other than are the fossils from widely separated formations. Such is the sum of the several chief objections and difficulties which may justly be urged against the theory; and I have now briefly recapitulated the answers and explanations which, as far as I can see, may be given. I have felt these difficulties far too heavily during many years to doubt their weight. But it deserves especial notice that the more important objections relate to questions on which we are confessedly ignorant; nor do we know how ignorant we are. We do not know all the possible transitional gradations between the simplest and the most perfect organs; it cannot be pretended that we know all the varied means of Distribution during the long lapse of years, or that we know how imperfect is the Geological Record. Serious as these several objections are, in my judgment they are by no means sufficient to overthrow the theory of descent with subsequent modification. Now let us turn to the other side of the argument. Under domestication we see much variability, caused, or at least excited, by changed conditions of life; but often in so obscure a manner, that we are tempted to consider the variations as spontaneous. Variability is governed by many complex laws, by correlated growth, compensation, the increased use and disuse of parts, and the definite action of the surrounding conditions. There is much difficulty in ascertaining how largely our domestic productions have been modified; but we may safely infer that the amount has been large, and that modifications can be inherited for long periods. As long as the conditions of life remain the same, we have reason to believe that a modification, which has already been inherited for many generations, may continue to be inherited for an almost infinite number of generations. On the other hand we have evidence that variability, when it has once come into play, does not cease under domestication for a very long period; nor do we know that it ever ceases, for new varieties are still occasionally produced by our oldest domesticated productions. Variability is not actually caused by man; he only unintentionally exposes organic beings to new conditions of life and then nature acts on the organisation and causes it to vary. But man can and does select the variations given to him by nature, and thus accumulates them in any desired manner. He thus adapts animals and plants for his own benefit or pleasure. He may do this methodically, or he may do it unconsciously by preserving the individuals most useful or pleasing to him without any intention of altering the breed. It is certain that he can largely influence the character of a breed by selecting, in each successive generation, individual differences so slight as to be inappreciable except by an educated eye. This unconscious process of selection has been the great agency in the formation of the most distinct and useful domestic breeds. That many breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether many of them are varieties or aboriginally distinct species. There is no reason why the principles which have acted so efficiently under domestication should not have acted under nature. In the survival of favoured individuals and races, during the constantly recurrent Struggle for Existence, we see a powerful and ever-acting form of Selection. The struggle for existence inevitably follows from the high geometrical ratio of increase which is common to all organic beings. This high rate of increase is proved by calculation--by the rapid increase of many animals and plants during a succession of peculiar seasons, and when naturalised in new countries. More individuals are born than can possibly survive. A grain in the balance may determine which individuals shall live and which shall die--which variety or species shall increase in number, and which shall decrease, or finally become extinct. As the individuals of the same species come in all respects into the closest competition with each other, the struggle will generally be most severe between them; it will be almost equally severe between the varieties of the same species, and next in severity between the species of the same genus. On the other hand the struggle will often be severe between beings remote in the scale of nature. The slightest advantage in certain individuals, at any age or during any season, over those with which they come into competition, or better adaptation in however slight a degree to the surrounding physical conditions, will, in the long run, turn the balance. With animals having separated sexes, there will be in most cases a struggle between the males for the possession of the females. The most vigorous males, or those which have most successfully struggled with their conditions of life, will generally leave most progeny. But success will often depend on the males having special weapons or means of defence or charms; and a slight advantage will lead to victory. As geology plainly proclaims that each land has undergone great physical changes, we might have expected to find that organic beings have varied under nature, in the same way as they have varied under domestication. And if there has been any variability under nature, it would be an unaccountable fact if natural selection had not come into play. It has often been asserted, but the assertion is incapable of proof, that the amount of variation under nature is a strictly limited quantity. Man, though acting on external characters alone and often capriciously, can produce within a short period a great result by adding up mere individual differences in his domestic productions; and every one admits that species present individual differences. But, besides such differences, all naturalists admit that natural varieties exist, which are considered sufficiently distinct to be worthy of record in systematic works. No one has drawn any clear distinction between individual differences and slight varieties; or between more plainly marked varieties and subspecies and species. On separate continents, and on different parts of the same continent, when divided by barriers of any kind, and on outlying islands, what a multitude of forms exist, which some experienced naturalists rank as varieties, others as geographical races or sub species, and others as distinct, though closely allied species! If, then, animals and plants do vary, let it be ever so slightly or slowly, why should not variations or individual differences, which are in any way beneficial, be preserved and accumulated through natural selection, or the survival of the fittest? If man can by patience select variations useful to him, why, under changing and complex conditions of life, should not variations useful to nature's living products often arise, and be preserved or selected? What limit can be put to this power, acting during long ages and rigidly scrutinising the whole constitution, structure, and habits of each creature, favouring the good and rejecting the bad? I can see no limit to this power, in slowly and beautifully adapting each form to the most complex relations of life. The theory of natural selection, even if we look no further than this, seems to be in the highest degree probable. I have already recapitulated, as fairly as I could, the opposed difficulties and objections: now let us turn to the special facts and arguments in favour of the theory. On the view that species are only strongly marked and permanent varieties, and that each species first existed as a variety, we can see why it is that no line of demarcation can be drawn between species, commonly supposed to have been produced by special acts of creation, and varieties which are acknowledged to have been produced by secondary laws. On this same view we can understand how it is that in a region where many species of a genus have been produced, and where they now flourish, these same species should present many varieties; for where the manufactory of species has been active, we might expect, as a general rule, to find it still in action; and this is the case if varieties be incipient species. Moreover, the species of the larger genera, which afford the greater number of varieties or incipient species, retain to a certain degree the character of varieties; for they differ from each other by a less amount of difference than do the species of smaller genera. The closely allied species also of a larger genera apparently have restricted ranges, and in their affinities they are clustered in little groups round other species--in both respects resembling varieties. These are strange relations on the view that each species was independently created, but are intelligible if each existed first as a variety. As each species tends by its geometrical rate of reproduction to increase inordinately in number; and as the modified descendants of each species will be enabled to increase by as much as they become more diversified in habits and structure, so as to be able to seize on many and widely different places in the economy of nature, there will be a constant tendency in natural selection to preserve the most divergent offspring of any one species. Hence during a long-continued course of modification, the slight differences characteristic of varieties of the same species, tend to be augmented into the greater differences characteristic of the species of the same genus. New and improved varieties will inevitably supplant and exterminate the older, less improved and intermediate varieties; and thus species are rendered to a large extent defined and distinct objects. Dominant species belonging to the larger groups within each class tend to give birth to new and dominant forms; so that each large group tends to become still larger, and at the same time more divergent in character. But as all groups cannot thus go on increasing in size, for the world would not hold them, the more dominant groups beat the less dominant. This tendency in the large groups to go on increasing in size and diverging in character, together with the inevitable contingency of much extinction, explains the arrangement of all the forms of life in groups subordinate to groups, all within a few great classes, which has prevailed throughout all time. This grand fact of the grouping of all organic beings under what is called the Natural System, is utterly inexplicable on the theory of creation. As natural selection acts solely by accumulating slight, successive, favourable variations, it can produce no great or sudden modifications; it can act only by short and slow steps. Hence, the canon of "Natura non facit saltum," which every fresh addition to our knowledge tends to confirm, is on this theory intelligible. We can see why throughout nature the same general end is gained by an almost infinite diversity of means, for every peculiarity when once acquired is long inherited, and structures already modified in many different ways have to be adapted for the same general purpose. We can, in short, see why nature is prodigal in variety, though niggard in innovation. But why this should be a law of nature if each species has been independently created no man can explain. Many other facts are, as it seems to me, explicable on this theory. How strange it is that a bird, under the form of a woodpecker, should prey on insects on the ground; that upland geese, which rarely or never swim, would possess webbed feet; that a thrush-like bird should dive and feed on sub-aquatic insects; and that a petrel should have the habits and structure fitting it for the life of an auk! and so in endless other cases. But on the view of each species constantly trying to increase in number, with natural selection always ready to adapt the slowly varying descendants of each to any unoccupied or ill-occupied place in nature, these facts cease to be strange, or might even have been anticipated. We can to a certain extent understand how it is that there is so much beauty throughout nature; for this may be largely attributed to the agency of selection. That beauty, according to our sense of it, is not universal, must be admitted by every one who will look at some venomous snakes, at some fishes, and at certain hideous bats with a distorted resemblance to the human face. Sexual selection has given the most brilliant colours, elegant patterns, and other ornaments to the males, and sometimes to both sexes of many birds, butterflies and other animals. With birds it has often rendered the voice of the male musical to the female, as well as to our ears. Flowers and fruit have been rendered conspicuous by brilliant colours in contrast with the green foliage, in order that the flowers may be easily seen, visited and fertilised by insects, and the seeds disseminated by birds. How it comes that certain colours, sounds and forms should give pleasure to man and the lower animals, that is, how the sense of beauty in its simplest form was first acquired, we do not know any more than how certain odours and flavours were first rendered agreeable. As natural selection acts by competition, it adapts and improves the inhabitants of each country only in relation to their co-inhabitants; so that we need feel no surprise at the species of any one country, although on the ordinary view supposed to have been created and specially adapted for that country, being beaten and supplanted by the naturalised productions from another land. Nor ought we to marvel if all the contrivances in nature be not, as far as we can judge, absolutely perfect; as in the case even of the human eye; or if some of them be abhorrent to our ideas of fitness. We need not marvel at the sting of the bee, when used against the enemy, causing the bee's own death; at drones being produced in such great numbers for one single act, and being then slaughtered by their sterile sisters; at the astonishing waste of pollen by our fir-trees; at the instinctive hatred of the queen-bee for her own fertile daughters; at ichneumonidae feeding within the living bodies of caterpillars; and at other such cases. The wonder, indeed, is, on the theory of natural selection, that more cases of the want of absolute perfection have not been detected. The complex and little known laws governing the production of varieties are the same, as far as we can judge, with the laws which have governed the production of distinct species. In both cases physical conditions seem to have produced some direct and definite effect, but how much we cannot say. Thus, when varieties enter any new station, they occasionally assume some of the characters proper to the species of that station. With both varieties and species, use and disuse seem to have produced a considerable effect; for it is impossible to resist this conclusion when we look, for instance, at the logger-headed duck, which has wings incapable of flight, in nearly the same condition as in the domestic duck; or when we look at the burrowing tucu-tucu, which is occasionally blind, and then at certain moles, which are habitually blind and have their eyes covered with skin; or when we look at the blind animals inhabiting the dark caves of America and Europe. With varieties and species, correlated variation seems to have played an important part, so that when one part has been modified other parts have been necessarily modified. With both varieties and species, reversions to long-lost characters occasionally occur. How inexplicable on the theory of creation is the occasional appearance of stripes on the shoulders and legs of the several species of the horse-genus and of their hybrids! How simply is this fact explained if we believe that these species are all descended from a striped progenitor, in the same manner as the several domestic breeds of the pigeon are descended from the blue and barred rock-pigeon! On the ordinary view of each species having been independently created, why should specific characters, or those by which the species of the same genus differ from each other, be more variable than the generic characters in which they all agree? Why, for instance, should the colour of a flower be more likely to vary in any one species of a genus, if the other species possess differently coloured flowers, than if all possessed the same coloured flowers? If species are only well-marked varieties, of which the characters have become in a high degree permanent, we can understand this fact; for they have already varied since they branched off from a common progenitor in certain characters, by which they have come to be specifically distinct from each other; therefore these same characters would be more likely again to vary than the generic characters which have been inherited without change for an immense period. It is inexplicable on the theory of creation why a part developed in a very unusual manner in one species alone of a genus, and therefore, as we may naturally infer, of great importance to that species, should be eminently liable to variation; but, on our view, this part has undergone, since the several species branched off from a common progenitor, an unusual amount of variability and modification, and therefore we might expect the part generally to be still variable. But a part may be developed in the most unusual manner, like the wing of a bat, and yet not be more variable than any other structure, if the part be common to many subordinate forms, that is, if it has been inherited for a very long period; for in this case it will have been rendered constant by long-continued natural selection. Glancing at instincts, marvellous as some are, they offer no greater difficulty than do corporeal structures on the theory of the natural selection of successive, slight, but profitable modifications. We can thus understand why nature moves by graduated steps in endowing different animals of the same class with their several instincts. I have attempted to show how much light the principle of gradation throws on the admirable architectural powers of the hive-bee. Habit no doubt often comes into play in modifying instincts; but it certainly is not indispensable, as we see in the case of neuter insects, which leave no progeny to inherit the effects of long-continued habit. On the view of all the species of the same genus having descended from a common parent, and having inherited much in common, we can understand how it is that allied species, when placed under widely different conditions of life, yet follow nearly the same instincts; why the thrushes of tropical and temperate South America, for instance, line their nests with mud like our British species. On the view of instincts having been slowly acquired through natural selection, we need not marvel at some instincts being not perfect and liable to mistakes, and at many instincts causing other animals to suffer. If species be only well-marked and permanent varieties, we can at once see why their crossed offspring should follow the same complex laws in their degrees and kinds of resemblance to their parents--in being absorbed into each other by successive crosses, and in other such points--as do the crossed offspring of acknowledged varieties. This similarity would be a strange fact, if species had been independently created and varieties had been produced through secondary laws. If we admit that the geological record is imperfect to an extreme degree, then the facts, which the record does give, strongly support the theory of descent with modification. New species have come on the stage slowly and at successive intervals; and the amount of change after equal intervals of time, is widely different in different groups. The extinction of species and of whole groups of species, which has played so conspicuous a part in the history of the organic world, almost inevitably follows from the principle of natural selection; for old forms are supplanted by new and improved forms. Neither single species nor groups of species reappear when the chain of ordinary generation is once broken. The gradual diffusion of dominant forms, with the slow modification of their descendants, causes the forms of life, after long intervals of time, to appear as if they had changed simultaneously throughout the world. The fact of the fossil remains of each formation being in some degree intermediate in character between the fossils in the formations above and below, is simply explained by their intermediate position in the chain of descent. The grand fact that all extinct beings can be classed with all recent beings, naturally follows from the living and the extinct being the offspring of common parents. As species have generally diverged in character during their long course of descent and modification, we can understand why it is that the more ancient forms, or early progenitors of each group, so often occupy a position in some degree intermediate between existing groups. Recent forms are generally looked upon as being, on the whole, higher in the scale of organisation than ancient forms; and they must be higher, in so far as the later and more improved forms have conquered the older and less improved forms in the struggle for life; they have also generally had their organs more specialised for different functions. This fact is perfectly compatible with numerous beings still retaining simple and but little improved structures, fitted for simple conditions of life; it is likewise compatible with some forms having retrograded in organisation, by having become at each stage of descent better fitted for new and degraded habits of life. Lastly, the wonderful law of the long endurance of allied forms on the same continent--of marsupials in Australia, of edentata in America, and other such cases--is intelligible, for within the same country the existing and the extinct will be closely allied by descent. Looking to geographical distribution, if we admit that there has been during the long course of ages much migration from one part of the world to another, owing to former climatical and geographical changes and to the many occasional and unknown means of dispersal, then we can understand, on the theory of descent with modification, most of the great leading facts in Distribution. We can see why there should be so striking a parallelism in the distribution of organic beings throughout space, and in their geological succession throughout time; for in both cases the beings have been connected by the bond of ordinary generation, and the means of modification have been the same. We see the full meaning of the wonderful fact, which has struck every traveller, namely, that on the same continent, under the most diverse conditions, under heat and cold, on mountain and lowland, on deserts and marshes, most of the inhabitants within each great class are plainly related; for they are the descendants of the same progenitors and early colonists. On this same principle of former migration, combined in most cases with modification, we can understand, by the aid of the Glacial period, the identity of some few plants, and the close alliance of many others, on the most distant mountains, and in the northern and southern temperate zones; and likewise the close alliance of some of the inhabitants of the sea in the northern and southern temperate latitudes, though separated by the whole intertropical ocean. Although two countries may present physical conditions as closely similar as the same species ever require, we need feel no surprise at their inhabitants being widely different, if they have been for a long period completely sundered from each other; for as the relation of organism to organism is the most important of all relations, and as the two countries will have received colonists at various periods and in different proportions, from some other country or from each other, the course of modification in the two areas will inevitably have been different. On this view of migration, with subsequent modification, we see why oceanic islands are inhabited by only few species, but of these, why many are peculiar or endemic forms. We clearly see why species belonging to those groups of animals which cannot cross wide spaces of the ocean, as frogs and terrestrial mammals, do not inhabit oceanic islands; and why, on the other hand, new and peculiar species of bats, animals which can traverse the ocean, are often found on islands far distant from any continent. Such cases as the presence of peculiar species of bats on oceanic islands and the absence of all other terrestrial mammals, are facts utterly inexplicable on the theory of independent acts of creation. The existence of closely allied representative species in any two areas, implies, on the theory of descent with modification, that the same parent-forms formerly inhabited both areas; and we almost invariably find that wherever many closely allied species inhabit two areas, some identical species are still common to both. Wherever many closely allied yet distinct species occur, doubtful forms and varieties belonging to the same groups likewise occur. It is a rule of high generality that the inhabitants of each area are related to the inhabitants of the nearest source whence immigrants might have been derived. We see this in the striking relation of nearly all the plants and animals of the Galapagos Archipelago, of Juan Fernandez, and of the other American islands, to the plants and animals of the neighbouring American mainland; and of those of the Cape de Verde Archipelago, and of the other African islands to the African mainland. It must be admitted that these facts receive no explanation on the theory of creation. The fact, as we have seen, that all past and present organic beings can be arranged within a few great classes, in groups subordinate to groups, and with the extinct groups often falling in between the recent groups, is intelligible on the theory of natural selection with its contingencies of extinction and divergence of character. On these same principles we see how it is that the mutual affinities of the forms within each class are so complex and circuitous. We see why certain characters are far more serviceable than others for classification; why adaptive characters, though of paramount importance to the beings, are of hardly any importance in classification; why characters derived from rudimentary parts, though of no service to the beings, are often of high classificatory value; and why embryological characters are often the most valuable of all. The real affinities of all organic beings, in contradistinction to their adaptive resemblances, are due to inheritance or community of descent. The Natural System is a genealogical arrangement, with the acquired grades of difference, marked by the terms, varieties, species, genera, families, etc.; and we have to discover the lines of descent by the most permanent characters, whatever they may be, and of however slight vital importance. The similar framework of bones in the hand of a man, wing of a bat, fin of the porpoise, and leg of the horse--the same number of vertebrae forming the neck of the giraffe and of the elephant--and innumerable other such facts, at once explain themselves on the theory of descent with slow and slight successive modifications. The similarity of pattern in the wing and in the leg of a bat, though used for such different purpose--in the jaws and legs of a crab--in the petals, stamens, and pistils of a flower, is likewise, to a large extent, intelligible on the view of the gradual modification of parts or organs, which were aboriginally alike in an early progenitor in each of these classes. On the principle of successive variations not always supervening at an early age, and being inherited at a corresponding not early period of life, we clearly see why the embryos of mammals, birds, reptiles, and fishes should be so closely similar, and so unlike the adult forms. We may cease marvelling at the embryo of an air-breathing mammal or bird having branchial slits and arteries running in loops, like those of a fish which has to breathe the air dissolved in water by the aid of well-developed branchiae. Disuse, aided sometimes by natural selection, will often have reduced organs when rendered useless under changed habits or conditions of life; and we can understand on this view the meaning of rudimentary organs. But disuse and selection will generally act on each creature, when it has come to maturity and has to play its full part in the struggle for existence, and will thus have little power on an organ during early life; hence the organ will not be reduced or rendered rudimentary at this early age. The calf, for instance, has inherited teeth, which never cut through the gums of the upper jaw, from an early progenitor having well-developed teeth; and we may believe, that the teeth in the mature animal were formerly reduced by disuse owing to the tongue and palate, or lips, having become excellently fitted through natural selection to browse without their aid; whereas in the calf, the teeth have been left unaffected, and on the principle of inheritance at corresponding ages have been inherited from a remote period to the present day. On the view of each organism with all its separate parts having been specially created, how utterly inexplicable is it that organs bearing the plain stamp of inutility, such as the teeth in the embryonic calf or the shrivelled wings under the soldered wing-covers of many beetles, should so frequently occur. Nature may be said to have taken pains to reveal her scheme of modification, by means of rudimentary organs, of embryological and homologous structures, but we are too blind to understand her meaning. I have now recapitulated the facts and considerations which have thoroughly convinced me that species have been modified, during a long course of descent. This has been effected chiefly through the natural selection of numerous successive, slight, favourable variations; aided in an important manner by the inherited effects of the use and disuse of parts; and in an unimportant manner, that is, in relation to adaptive structures, whether past or present, by the direct action of external conditions, and by variations which seem to us in our ignorance to arise spontaneously. It appears that I formerly underrated the frequency and value of these latter forms of variation, as leading to permanent modifications of structure independently of natural selection. But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position--namely, at the close of the Introduction--the following words: "I am convinced that natural selection has been the main but not the exclusive means of modification." This has been of no avail. Great is the power of steady misrepresentation; but the history of science shows that fortunately this power does not long endure. It can hardly be supposed that a false theory would explain, in so satisfactory a manner as does the theory of natural selection, the several large classes of facts above specified. It has recently been objected that this is an unsafe method of arguing; but it is a method used in judging of the common events of life, and has often been used by the greatest natural philosophers. The undulatory theory of light has thus been arrived at; and the belief in the revolution of the earth on its own axis was until lately supported by hardly any direct evidence. It is no valid objection that science as yet throws no light on the far higher problem of the essence or origin of life. Who can explain what is the essence of the attraction of gravity? No one now objects to following out the results consequent on this unknown element of attraction; notwithstanding that Leibnitz formerly accused Newton of introducing "occult qualities and miracles into philosophy." I see no good reasons why the views given in this volume should shock the religious feelings of any one. It is satisfactory, as showing how transient such impressions are, to remember that the greatest discovery ever made by man, namely, the law of the attraction of gravity, was also attacked by Leibnitz, "as subversive of natural, and inferentially of revealed, religion." A celebrated author and divine has written to me that "he has gradually learned to see that it is just as noble a conception of the Deity to believe that He created a few original forms capable of self-development into other and needful forms, as to believe that He required a fresh act of creation to supply the voids caused by the action of His laws." Why, it may be asked, until recently did nearly all the most eminent living naturalists and geologists disbelieve in the mutability of species? It cannot be asserted that organic beings in a state of nature are subject to no variation; it cannot be proved that the amount of variation in the course of long ages is a limited quantity; no clear distinction has been, or can be, drawn between species and well-marked varieties. It cannot be maintained that species when intercrossed are invariably sterile and varieties invariably fertile; or that sterility is a special endowment and sign of creation. The belief that species were immutable productions was almost unavoidable as long as the history of the world was thought to be of short duration; and now that we have acquired some idea of the lapse of time, we are too apt to assume, without proof, that the geological record is so perfect that it would have afforded us plain evidence of the mutation of species, if they had undergone mutation. But the chief cause of our natural unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting any great changes of which we do not see the steps. The difficulty is the same as that felt by so many geologists, when Lyell first insisted that long lines of inland cliffs had been formed, and great valleys excavated, by the agencies which we still see at work. The mind cannot possibly grasp the full meaning of the term of even a million years; it cannot add up and perceive the full effects of many slight variations, accumulated during an almost infinite number of generations. Although I am fully convinced of the truth of the views given in this volume under the form of an abstract, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as the "plan of creation," "unity of design," etc., and to think that we give an explanation when we only restate a fact. Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject the theory. A few naturalists, endowed with much flexibility of mind, and who have already begun to doubt the immutability of species, may be influenced by this volume; but I look with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality. Whoever is led to believe that species are mutable will do good service by conscientiously expressing his conviction; for thus only can the load of prejudice by which this subject is overwhelmed be removed. Several eminent naturalists have of late published their belief that a multitude of reputed species in each genus are not real species; but that other species are real, that is, have been independently created. This seems to me a strange conclusion to arrive at. They admit that a multitude of forms, which till lately they themselves thought were special creations, and which are still thus looked at by the majority of naturalists, and which consequently have all the external characteristic features of true species--they admit that these have been produced by variation, but they refuse to extend the same view to other and slightly different forms. Nevertheless, they do not pretend that they can define, or even conjecture, which are the created forms of life, and which are those produced by secondary laws. They admit variation as a vera causa in one case, they arbitrarily reject it in another, without assigning any distinction in the two cases. The day will come when this will be given as a curious illustration of the blindness of preconceived opinion. These authors seem no more startled at a miraculous act of creation than at an ordinary birth. But do they really believe that at innumerable periods in the earth's history certain elemental atoms have been commanded suddenly to flash into living tissues? Do they believe that at each supposed act of creation one individual or many were produced? Were all the infinitely numerous kinds of animals and plants created as eggs or seed, or as full grown? and in the case of mammals, were they created bearing the false marks of nourishment from the mother's womb? Undoubtedly some of these same questions cannot be answered by those who believe in the appearance or creation of only a few forms of life or of some one form alone. It has been maintained by several authors that it is as easy to believe in the creation of a million beings as of one; but Maupertuis' philosophical axiom "of least action" leads the mind more willingly to admit the smaller number; and certainly we ought not to believe that innumerable beings within each great class have been created with plain, but deceptive, marks of descent from a single parent. As a record of a former state of things, I have retained in the foregoing paragraphs, and elsewhere, several sentences which imply that naturalists believe in the separate creation of each species; and I have been much censured for having thus expressed myself. But undoubtedly this was the general belief when the first edition of the present work appeared. I formerly spoke to very many naturalists on the subject of evolution, and never once met with any sympathetic agreement. It is probable that some did then believe in evolution, but they were either silent or expressed themselves so ambiguously that it was not easy to understand their meaning. Now, things are wholly changed, and almost every naturalist admits the great principle of evolution. There are, however, some who still think that species have suddenly given birth, through quite unexplained means, to new and totally different forms. But, as I have attempted to show, weighty evidence can be opposed to the admission of great and abrupt modifications. Under a scientific point of view, and as leading to further investigation, but little advantage is gained by believing that new forms are suddenly developed in an inexplicable manner from old and widely different forms, over the old belief in the creation of species from the dust of the earth. It may be asked how far I extend the doctrine of the modification of species. The question is difficult to answer, because the more distinct the forms are which we consider, by so much the arguments in favour of community of descent become fewer in number and less in force. But some arguments of the greatest weight extend very far. All the members of whole classes are connected together by a chain of affinities, and all can be classed on the same principle, in groups subordinate to groups. Fossil remains sometimes tend to fill up very wide intervals between existing orders. Organs in a rudimentary condition plainly show that an early progenitor had the organ in a fully developed condition, and this in some cases implies an enormous amount of modification in the descendants. Throughout whole classes various structures are formed on the same pattern, and at a very early age the embryos closely resemble each other. Therefore I cannot doubt that the theory of descent with modification embraces all the members of the same great class or kingdom. I believe that animals are descended from at most only four or five progenitors, and plants from an equal or lesser number. Analogy would lead me one step further, namely, to the belief that all animals and plants are descended from some one prototype. But analogy may be a deceitful guide. Nevertheless all living things have much in common, in their chemical composition, their cellular structure, their laws of growth, and their liability to injurious influences. We see this even in so trifling a fact as that the same poison often similarly affects plants and animals; or that the poison secreted by the gall-fly produces monstrous growths on the wild rose or oak-tree. With all organic beings, excepting perhaps some of the very lowest, sexual reproduction seems to be essentially similar. With all, as far as is at present known, the germinal vesicle is the same; so that all organisms start from a common origin. If we look even to the two main divisions--namely, to the animal and vegetable kingdoms--certain low forms are so far intermediate in character that naturalists have disputed to which kingdom they should be referred. As Professor Asa Gray has remarked, "the spores and other reproductive bodies of many of the lower algae may claim to have first a characteristically animal, and then an unequivocally vegetable existence." Therefore, on the principle of natural selection with divergence of character, it does not seem incredible that, from some such low and intermediate form, both animals and plants may have been developed; and, if we admit this, we must likewise admit that all the organic beings which have ever lived on this earth may be descended from some one primordial form. But this inference is chiefly grounded on analogy, and it is immaterial whether or not it be accepted. No doubt it is possible, as Mr. G.H. Lewes has urged, that at the first commencement of life many different forms were evolved; but if so, we may conclude that only a very few have left modified descendants. For, as I have recently remarked in regard to the members of each great kingdom, such as the Vertebrata, Articulata, etc., we have distinct evidence in their embryological, homologous, and rudimentary structures, that within each kingdom all the members are descended from a single progenitor. When the views advanced by me in this volume, and by Mr. Wallace or when analogous views on the origin of species are generally admitted, we can dimly foresee that there will be a considerable revolution in natural history. Systematists will be able to pursue their labours as at present; but they will not be incessantly haunted by the shadowy doubt whether this or that form be a true species. This, I feel sure and I speak after experience, will be no slight relief. The endless disputes whether or not some fifty species of British brambles are good species will cease. Systematists will have only to decide (not that this will be easy) whether any form be sufficiently constant and distinct from other forms, to be capable of definition; and if definable, whether the differences be sufficiently important to deserve a specific name. This latter point will become a far more essential consideration than it is at present; for differences, however slight, between any two forms, if not blended by intermediate gradations, are looked at by most naturalists as sufficient to raise both forms to the rank of species. Hereafter we shall be compelled to acknowledge that the only distinction between species and well-marked varieties is, that the latter are known, or believed to be connected at the present day by intermediate gradations, whereas species were formerly thus connected. Hence, without rejecting the consideration of the present existence of intermediate gradations between any two forms, we shall be led to weigh more carefully and to value higher the actual amount of difference between them. It is quite possible that forms now generally acknowledged to be merely varieties may hereafter be thought worthy of specific names; and in this case scientific and common language will come into accordance. In short, we shall have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial combinations made for convenience. This may not be a cheering prospect; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species. The other and more general departments of natural history will rise greatly in interest. The terms used by naturalists, of affinity, relationship, community of type, paternity, morphology, adaptive characters, rudimentary and aborted organs, etc., will cease to be metaphorical and will have a plain signification. When we no longer look at an organic being as a savage looks at a ship, as something wholly beyond his comprehension; when we regard every production of nature as one which has had a long history; when we contemplate every complex structure and instinct as the summing up of many contrivances, each useful to the possessor, in the same way as any great mechanical invention is the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen; when we thus view each organic being, how far more interesting--I speak from experience--does the study of natural history become! A grand and almost untrodden field of inquiry will be opened, on the causes and laws of variation, on correlation, on the effects of use and disuse, on the direct action of external conditions, and so forth. The study of domestic productions will rise immensely in value. A new variety raised by man will be a far more important and interesting subject for study than one more species added to the infinitude of already recorded species. Our classifications will come to be, as far as they can be so made, genealogies; and will then truly give what may be called the plan of creation. The rules for classifying will no doubt become simpler when we have a definite object in view. We possess no pedigree or armorial bearings; and we have to discover and trace the many diverging lines of descent in our natural genealogies, by characters of any kind which have long been inherited. Rudimentary organs will speak infallibly with respect to the nature of long-lost structures. Species and groups of species which are called aberrant, and which may fancifully be called living fossils, will aid us in forming a picture of the ancient forms of life. Embryology will often reveal to us the structure, in some degree obscured, of the prototypes of each great class. When we can feel assured that all the individuals of the same species, and all the closely allied species of most genera, have, within a not very remote period descended from one parent, and have migrated from some one birth-place; and when we better know the many means of migration, then, by the light which geology now throws, and will continue to throw, on former changes of climate and of the level of the land, we shall surely be enabled to trace in an admirable manner the former migrations of the inhabitants of the whole world. Even at present, by comparing the differences between the inhabitants of the sea on the opposite sides of a continent, and the nature of the various inhabitants of that continent in relation to their apparent means of immigration, some light can be thrown on ancient geography. The noble science of geology loses glory from the extreme imperfection of the record. The crust of the earth, with its embedded remains, must not be looked at as a well-filled museum, but as a poor collection made at hazard and at rare intervals. The accumulation of each great fossiliferous formation will be recognised as having depended on an unusual occurrence of favourable circumstances, and the blank intervals between the successive stages as having been of vast duration. But we shall be able to gauge with some security the duration of these intervals by a comparison of the preceding and succeeding organic forms. We must be cautious in attempting to correlate as strictly contemporaneous two formations, which do not include many identical species, by the general succession of the forms of life. As species are produced and exterminated by slowly acting and still existing causes, and not by miraculous acts of creation; and as the most important of all causes of organic change is one which is almost independent of altered and perhaps suddenly altered physical conditions, namely, the mutual relation of organism to organism--the improvement of one organism entailing the improvement or the extermination of others; it follows, that the amount of organic change in the fossils of consecutive formations probably serves as a fair measure of the relative, though not actual lapse of time. A number of species, however, keeping in a body might remain for a long period unchanged, whilst within the same period, several of these species, by migrating into new countries and coming into competition with foreign associates, might become modified; so that we must not overrate the accuracy of organic change as a measure of time. In the future I see open fields for far more important researches. Psychology will be securely based on the foundation already well laid by Mr. Herbert Spencer, that of the necessary acquirement of each mental power and capacity by gradation. Much light will be thrown on the origin of man and his history. Authors of the highest eminence seem to be fully satisfied with the view that each species has been independently created. To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual. When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Cambrian system was deposited, they seem to me to become ennobled. Judging from the past, we may safely infer that not one living species will transmit its unaltered likeness to a distinct futurity. And of the species now living very few will transmit progeny of any kind to a far distant futurity; for the manner in which all organic beings are grouped, shows that the greater number of species in each genus, and all the species in many genera, have left no descendants, but have become utterly extinct. We can so far take a prophetic glance into futurity as to foretell that it will be the common and widely spread species, belonging to the larger and dominant groups within each class, which will ultimately prevail and procreate new and dominant species. As all the living forms of life are the lineal descendants of those which lived long before the Cambrian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no cataclysm has desolated the whole world. Hence, we may look with some confidence to a secure future of great length. And as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection. It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone circling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved. GLOSSARY OF THE PRINCIPAL SCIENTIFIC TERMS USED IN THE PRESENT VOLUME. (I am indebted to the kindness of Mr. W.S. Dallas for this Glossary, which has been given because several readers have complained to me that some of the terms used were unintelligible to them. Mr. Dallas has endeavoured to give the explanations of the terms in as popular a form as possible.) ABERRANT.--Forms or groups of animals or plants which deviate in important characters from their nearest allies, so as not to be easily included in the same group with them, are said to be aberrant. ABERRATION (in Optics).--In the refraction of light by a convex lens the rays passing through different parts of the lens are brought to a focus at slightly different distances--this is called SPHERICAL ABERRATION; at the same time the coloured rays are separated by the prismatic action of the lens and likewise brought to a focus at different distances--this is CHROMATIC ABERRATION. ABNORMAL.--Contrary to the general rule. ABORTED.--An organ is said to be aborted, when its development has been arrested at a very early stage. ALBINISM.--Albinos are animals in which the usual colouring matters characteristic of the species have not been produced in the skin and its appendages. Albinism is the state of being an albino. ALGAE.--A class of plants including the ordinary sea-weeds and the filamentous fresh-water weeds. ALTERNATION OF GENERATIONS.--This term is applied to a peculiar mode of reproduction which prevails among many of the lower animals, in which the egg produces a living form quite different from its parent, but from which the parent-form is reproduced by a process of budding, or by the division of the substance of the first product of the egg. AMMONITES.--A group of fossil, spiral, chambered shells, allied to the existing pearly Nautilus, but having the partitions between the chambers waved in complicated patterns at their junction with the outer wall of the shell. ANALOGY.--That resemblance of structures which depends upon similarity of function, as in the wings of insects and birds. Such structures are said to be ANALOGOUS, and to be ANALOGUES of each other. ANIMALCULE.--A minute animal: generally applied to those visible only by the microscope. ANNELIDS.--A class of worms in which the surface of the body exhibits a more or less distinct division into rings or segments, generally provided with appendages for locomotion and with gills. It includes the ordinary marine worms, the earth-worms, and the leeches. ANTENNAE.--Jointed organs appended to the head in Insects, Crustacea and Centipedes, and not belonging to the mouth. ANTHERS.--The summits of the stamens of flowers, in which the pollen or fertilising dust is produced. APLACENTALIA, APLACENTATA or APLACENTAL MAMMALS.--See MAMMALIA. ARCHETYPAL.--Of or belonging to the Archetype, or ideal primitive form upon which all the beings of a group seem to be organised. ARTICULATA.--A great division of the Animal Kingdom characterised generally by having the surface of the body divided into rings called segments, a greater or less number of which are furnished with jointed legs (such as Insects, Crustaceans and Centipedes). ASYMMETRICAL.--Having the two sides unlike. ATROPHIED.--Arrested in development at a very early stage. BALANUS.--The genus including the common Acorn-shells which live in abundance on the rocks of the sea-coast. BATRACHIANS.--A class of animals allied to the Reptiles, but undergoing a peculiar metamorphosis, in which the young animal is generally aquatic and breathes by gills. (Examples, Frogs, Toads, and Newts.) BOULDERS.--Large transported blocks of stone generally embedded in clays or gravels. BRACHIOPODA.--A class of marine Mollusca, or soft-bodied animals, furnished with a bivalve shell, attached to submarine objects by a stalk which passes through an aperture in one of the valves, and furnished with fringed arms, by the action of which food is carried to the mouth. BRANCHIAE.--Gills or organs for respiration in water. BRANCHIAL.--Pertaining to gills or branchiae. CAMBRIAN SYSTEM.--A series of very ancient Palaeozoic rocks, between the Laurentian and the Silurian. Until recently these were regarded as the oldest fossiliferous rocks. CANIDAE.--The Dog-family, including the Dog, Wolf, Fox, Jackal, etc. CARAPACE.--The shell enveloping the anterior part of the body in Crustaceans generally; applied also to the hard shelly pieces of the Cirripedes. CARBONIFEROUS.--This term is applied to the great formation which includes, among other rocks, the coal-measures. It belongs to the oldest, or Palaeozoic, system of formations. CAUDAL.--Of or belonging to the tail. CEPHALOPODS.--The highest class of the Mollusca, or soft-bodied animals, characterised by having the mouth surrounded by a greater or less number of fleshy arms or tentacles, which, in most living species, are furnished with sucking-cups. (Examples, Cuttle-fish, Nautilus.) CETACEA.--An order of Mammalia, including the Whales, Dolphins, etc., having the form of the body fish-like, the skin naked, and only the fore limbs developed. CHELONIA.--An order of Reptiles including the Turtles, Tortoises, etc. CIRRIPEDES.--An order of Crustaceans including the Barnacles and Acorn-shells. Their young resemble those of many other Crustaceans in form; but when mature they are always attached to other objects, either directly or by means of a stalk, and their bodies are enclosed by a calcareous shell composed of several pieces, two of which can open to give issue to a bunch of curled, jointed tentacles, which represent the limbs. COCCUS.--The genus of Insects including the Cochineal. In these the male is a minute, winged fly, and the female generally a motionless, berry-like mass. COCOON.--A case usually of silky material, in which insects are frequently enveloped during the second or resting-stage (pupa) of their existence. The term "cocoon-stage" is here used as equivalent to "pupa-stage." COELOSPERMOUS.--A term applied to those fruits of the Umbelliferae which have the seed hollowed on the inner face. COLEOPTERA.--Beetles, an order of Insects, having a biting mouth and the first pair of wings more or less horny, forming sheaths for the second pair, and usually meeting in a straight line down the middle of the back. COLUMN.--A peculiar organ in the flowers of Orchids, in which the stamens, style and stigma (or the reproductive parts) are united. COMPOSITAE or COMPOSITOUS PLANTS.--Plants in which the inflorescence consists of numerous small flowers (florets) brought together into a dense head, the base of which is enclosed by a common envelope. (Examples, the Daisy, Dandelion, etc.) CONFERVAE.--The filamentous weeds of fresh water. CONGLOMERATE.--A rock made up of fragments of rock or pebbles, cemented together by some other material. COROLLA.--The second envelope of a flower usually composed of coloured, leaf-like organs (petals), which may be united by their edges either in the basal part or throughout. CORRELATION.--The normal coincidence of one phenomenon, character, etc., with another. CORYMB.--A bunch of flowers in which those springing from the lower part of the flower stalks are supported on long stalks so as to be nearly on a level with the upper ones. COTYLEDONS.--The first or seed-leaves of plants. CRUSTACEANS.--A class of articulated animals, having the skin of the body generally more or less hardened by the deposition of calcareous matter, breathing by means of gills. (Examples, Crab, Lobster, Shrimp, etc.) CURCULIO.--The old generic term for the Beetles known as Weevils, characterised by their four-jointed feet, and by the head being produced into a sort of beak, upon the sides of which the antennae are inserted. CUTANEOUS.--Of or belonging to the skin. DEGRADATION.--The wearing down of land by the action of the sea or of meteoric agencies. DENUDATION.--The wearing away of the surface of the land by water. DEVONIAN SYSTEM or FORMATION.--A series of Palaeozoic rocks, including the Old Red Sandstone. DICOTYLEDONS, or DICOTYLEDONOUS PLANTS.--A class of plants characterised by having two seed-leaves, by the formation of new wood between the bark and the old wood (exogenous growth) and by the reticulation of the veins of the leaves. The parts of the flowers are generally in multiples of five. DIFFERENTATION.--The separation or discrimination of parts or organs which in simpler forms of life are more or less united. DIMORPHIC.--Having two distinct forms.--DIMORPHISM is the condition of the appearance of the same species under two dissimilar forms. DIOECIOUS.--Having the organs of the sexes upon distinct individuals. DIORITE.--A peculiar form of Greenstone. DORSAL.--Of or belonging to the back. EDENTATA.--A peculiar order of Quadrupeds, characterised by the absence of at least the middle incisor (front) teeth in both jaws. (Examples, the Sloths and Armadillos.) ELYTRA.--The hardened fore-wings of Beetles, serving as sheaths for the membranous hind-wings, which constitute the true organs of flight. EMBRYO.--The young animal undergoing development within the egg or womb. EMBRYOLOGY.--The study of the development of the embryo. ENDEMIC.--Peculiar to a given locality. ENTOMOSTRACA.--A division of the class Crustacea, having all the segments of the body usually distinct, gills attached to the feet or organs of the mouth, and the feet fringed with fine hairs. They are generally of small size. EOCENE.--The earliest of the three divisions of the Tertiary epoch of geologists. Rocks of this age contain a small proportion of shells identical with species now living. EPHEMEROUS INSECTS.--Insects allied to the May-fly. FAUNA.--The totality of the animals naturally inhabiting a certain country or region, or which have lived during a given geological period. FELIDAE.--The Cat-family. FERAL.--Having become wild from a state of cultivation or domestication. FLORA.--The totality of the plants growing naturally in a country, or during a given geological period. FLORETS.--Flowers imperfectly developed in some respects, and collected into a dense spike or head, as in the Grasses, the Dandelion, etc. FOETAL.--Of or belonging to the foetus, or embryo in course of development. FORAMINIFERA.--A class of animals of very low organisation and generally of small size, having a jelly-like body, from the surface of which delicate filaments can be given off and retracted for the prehension of external objects, and having a calcareous or sandy shell, usually divided into chambers and perforated with small apertures. FOSSILIFEROUS.--Containing fossils. FOSSORIAL.--Having a faculty of digging. The Fossorial Hymenoptera are a group of Wasp-like Insects, which burrow in sandy soil to make nests for their young. FRENUM (pl. FRENA).--A small band or fold of skin. FUNGI (sing. FUNGUS).--A class of cellular plants, of which Mushrooms, Toadstools, and Moulds, are familiar examples. FURCULA.--The forked bone formed by the union of the collar-bones in many birds, such as the common Fowl. GALLINACEOUS BIRDS.--An order of birds of which the common Fowl, Turkey, and Pheasant, are well-known examples. GALLUS.--The genus of birds which includes the common Fowl. GANGLION.--A swelling or knot from which nerves are given off as from a centre. GANOID FISHES.--Fishes covered with peculiar enamelled bony scales. Most of them are extinct. GERMINAL VESICLE.--A minute vesicle in the eggs of animals, from which the development of the embryo proceeds. GLACIAL PERIOD.--A period of great cold and of enormous extension of ice upon the surface of the earth. It is believed that glacial periods have occurred repeatedly during the geological history of the earth, but the term is generally applied to the close of the Tertiary epoch, when nearly the whole of Europe was subjected to an arctic climate. GLAND.--An organ which secretes or separates some peculiar product from the blood or sap of animals or plants. GLOTTIS.--The opening of the windpipe into the oesophagus or gullet. GNEISS.--A rock approaching granite in composition, but more or less laminated, and really produced by the alteration of a sedimentary deposit after its consolidation. GRALLATORES.--The so-called wading-birds (storks, cranes, snipes, etc.), which are generally furnished with long legs, bare of feathers above the heel, and have no membranes between the toes. GRANITE.--A rock consisting essentially of crystals of felspar and mica in a mass of quartz. HABITAT.--The locality in which a plant or animal naturally lives. HEMIPTERA.--An order or sub-order of insects, characterised by the possession of a jointed beak or rostrum, and by having the fore-wings horny in the basal portion and membranous at the extremity, where they cross each other. This group includes the various species of bugs. HERMAPHRODITE.--Possessing the organs of both sexes. HOMOLOGY.--That relation between parts which results from their development from corresponding embryonic parts, either in different animals, as in the case of the arm of man, the fore-leg of a quadruped, and the wing of a bird; or in the same individual, as in the case of the fore and hind legs in quadrupeds, and the segments or rings and their appendages of which the body of a worm, a centipede, etc., is composed. The latter is called serial homology. The parts which stand in such a relation to each other are said to be homologous, and one such part or organ is called the homologue of the other. In different plants the parts of the flower are homologous, and in general these parts are regarded as homologous with leaves. HOMOPTERA.--An order or sub-order of insects having (like the Hemiptera) a jointed beak, but in which the fore-wings are either wholly membranous or wholly leathery, The Cicadae, frog-hoppers, and Aphides, are well-known examples. HYBRID.--The offspring of the union of two distinct species. HYMENOPTERA.--An order of insects possessing biting jaws and usually four membranous wings in which there are a few veins. Bees and wasps are familiar examples of this group. HYPERTROPHIED.--Excessively developed. ICHNEUMONIDAE.--A family of hymenopterous insects, the members of which lay their eggs in the bodies or eggs of other insects. IMAGO.--The perfect (generally winged) reproductive state of an insect. INDIGENES.--The aboriginal animal or vegetable inhabitants of a country or region. INFLORESCENCE.--The mode of arrangement of the flowers of plants. INFUSORIA.--A class of microscopic animalcules, so called from their having originally been observed in infusions of vegetable matters. They consist of a gelatinous material enclosed in a delicate membrane, the whole or part of which is furnished with short vibrating hairs (called cilia), by means of which the animalcules swim through the water or convey the minute particles of their food to the orifice of the mouth. INSECTIVOROUS.--Feeding on insects. INVERTEBRATA, or INVERTEBRATE ANIMALS.--Those animals which do not possess a backbone or spinal column. LACUNAE.--Spaces left among the tissues in some of the lower animals and serving in place of vessels for the circulation of the fluids of the body. LAMELLATED.--Furnished with lamellae or little plates. LARVA (pl. LARVAE).--The first condition of an insect at its issuing from the egg, when it is usually in the form of a grub, caterpillar, or maggot. LARYNX.--The upper part of the windpipe opening into the gullet. LAURENTIAN.--A group of greatly altered and very ancient rocks, which is greatly developed along the course of the St. Laurence, whence the name. It is in these that the earliest known traces of organic bodies have been found. LEGUMINOSAE.--An order of plants represented by the common peas and beans, having an irregular flower in which one petal stands up like a wing, and the stamens and pistil are enclosed in a sheath formed by two other petals. The fruit is a pod (or legume). LEMURIDAE.--A group of four-handed animals, distinct from the monkeys and approaching the insectivorous quadrupeds in some of their characters and habits. Its members have the nostrils curved or twisted, and a claw instead of a nail upon the first finger of the hind hands. LEPIDOPTERA.--An order of insects, characterised by the possession of a spiral proboscis, and of four large more or less scaly wings. It includes the well-known butterflies and moths. LITTORAL.--Inhabiting the seashore. LOESS.--A marly deposit of recent (Post-Tertiary) date, which occupies a great part of the valley of the Rhine. MALACOSTRACA.--The higher division of the Crustacea, including the ordinary crabs, lobsters, shrimps, etc., together with the woodlice and sand-hoppers. MAMMALIA.--The highest class of animals, including the ordinary hairy quadrupeds, the whales and man, and characterised by the production of living young which are nourished after birth by milk from the teats (MAMMAE, MAMMARY GLANDS) of the mother. A striking difference in embryonic development has led to the division of this class into two great groups; in one of these, when the embryo has attained a certain stage, a vascular connection, called the PLACENTA, is formed between the embryo and the mother; in the other this is wanting, and the young are produced in a very incomplete state. The former, including the greater part of the class, are called PLACENTAL MAMMALS; the latter, or APLACENTAL MAMMALS, include the Marsupials and Monotremes (ORNITHORHYNCHUS). MAMMIFEROUS.--Having mammae or teats (see MAMMALIA). MANDIBLES.--in insects, the first or uppermost pair of jaws, which are generally solid, horny, biting organs. In birds the term is applied to both jaws with their horny coverings. In quadrupeds the mandible is properly the lower jaw. MARSUPIALS.--An order of Mammalia in which the young are born in a very incomplete state of development, and carried by the mother, while sucking, in a ventral pouch (marsupium), such as the kangaroos, opossums, etc. (see MAMMALIA). MAXILLAE.--in insects, the second or lower pair of jaws, which are composed of several joints and furnished with peculiar jointed appendages called palpi, or feelers. MELANISM.--The opposite of albinism; an undue development of colouring material in the skin and its appendages. METAMORPHIC ROCKS.--Sedimentary rocks which have undergone alteration, generally by the action of heat, subsequently to their deposition and consolidation. MOLLUSCA.--One of the great divisions of the animal kingdom, including those animals which have a soft body, usually furnished with a shell, and in which the nervous ganglia, or centres, present no definite general arrangement. They are generally known under the denomination of "shellfish"; the cuttle-fish, and the common snails, whelks, oysters, mussels, and cockles, may serve as examples of them. MONOCOTYLEDONS, or MONOCOTYLEDONOUS PLANTS.--Plants in which the seed sends up only a single seed-leaf (or cotyledon); characterised by the absence of consecutive layers of wood in the stem (endogenous growth), by the veins of the leaves being generally straight, and by the parts of the flowers being generally in multiples of three. (Examples, grasses, lilies, orchids, palms, etc.) MORAINES.--The accumulations of fragments of rock brought down by glaciers. MORPHOLOGY.--The law of form or structure independent of function. MYSIS-STAGE.--A stage in the development of certain crustaceans (prawns), in which they closely resemble the adults of a genus (Mysis) belonging to a slightly lower group. NASCENT.--Commencing development. NATATORY.--Adapted for the purpose of swimming. NAUPLIUS-FORM.--The earliest stage in the development of many Crustacea, especially belonging to the lower groups. In this stage the animal has a short body, with indistinct indications of a division into segments, and three pairs of fringed limbs. This form of the common fresh-water CYCLOPS was described as a distinct genus under the name of NAUPLIUS. NEURATION.--The arrangement of the veins or nervures in the wings of insects. NEUTERS.--Imperfectly developed females of certain social insects (such as ants and bees), which perform all the labours of the community. Hence, they are also called WORKERS. NICTITATING MEMBRANE.--A semi-transparent membrane, which can be drawn across the eye in birds and reptiles, either to moderate the effects of a strong light or to sweep particles of dust, etc., from the surface of the eye. OCELLI.--The simple eyes or stemmata of insects, usually situated on the crown of the head between the great compound eyes. OESOPHAGUS.--The gullet. OOLITIC.--A great series of secondary rocks, so called from the texture of some of its members, which appear to be made up of a mass of small EGG-LIKE calcareous bodies. OPERCULUM.--A calcareous plate employed by many Molluscae to close the aperture of their shell. The OPERCULAR VALVES of Cirripedes are those which close the aperture of the shell. ORBIT.--The bony cavity for the reception of the eye. ORGANISM.--An organised being, whether plant or animal. ORTHOSPERMOUS.--A term applied to those fruits of the Umbelliferae which have the seed straight. OSCULANT.--Forms or groups apparently intermediate between and connecting other groups are said to be osculant. OVA.--Eggs. OVARIUM or OVARY (in plants).--The lower part of the pistil or female organ of the flower, containing the ovules or incipient seeds; by growth after the other organs of the flower have fallen, it usually becomes converted into the fruit. OVIGEROUS.--Egg-bearing. OVULES (of plants).--The seeds in the earliest condition. PACHYDERMS.--A group of Mammalia, so called from their thick skins, and including the elephant, rhinoceros, hippopotamus, etc. PALAEOZOIC.--The oldest system of fossiliferous rocks. PALPI.--Jointed appendages to some of the organs of the mouth in insects and Crustacea. PAPILIONACEAE.--An order of plants (see LEGUMINOSAE), The flowers of these plants are called PAPILIONACEOUS, or butterfly-like, from the fancied resemblance of the expanded superior petals to the wings of a butterfly. PARASITE.--An animal or plant living upon or in, and at the expense of, another organism. PARTHENOGENESIS.--The production of living organisms from unimpregnated eggs or seeds. PEDUNCULATED.--Supported upon a stem or stalk. The pedunculated oak has its acorns borne upon a footstool. PELORIA or PELORISM.--The appearance of regularity of structure in the flowers of plants which normally bear irregular flowers. PELVIS.--The bony arch to which the hind limbs of vertebrate animals are articulated. PETALS.--The leaves of the corolla, or second circle of organs in a flower. They are usually of delicate texture and brightly coloured. PHYLLODINEOUS.--Having flattened, leaf-like twigs or leafstalks instead of true leaves. PIGMENT.--The colouring material produced generally in the superficial parts of animals. The cells secreting it are called PIGMENT-CELLS. PINNATE.--Bearing leaflets on each side of a central stalk. PISTILS.--The female organs of a flower, which occupy a position in the centre of the other floral organs. The pistil is generally divisible into the ovary or germen, the style and the stigma. PLACENTALIA, PLACENTATA.--or PLACENTAL MAMMALS, See MAMMALIA. PLANTIGRADES.--Quadrupeds which walk upon the whole sole of the foot, like the bears. PLASTIC.--Readily capable of change. PLEISTOCENE PERIOD.--The latest portion of the Tertiary epoch. PLUMULE (in plants).--The minute bud between the seed-leaves of newly-germinated plants. PLUTONIC ROCKS.--Rocks supposed to have been produced by igneous action in the depths of the earth. POLLEN.--The male element in flowering plants; usually a fine dust produced by the anthers, which, by contact with the stigma effects the fecundation of the seeds. This impregnation is brought about by means of tubes (POLLEN-TUBES) which issue from the pollen-grains adhering to the stigma, and penetrate through the tissues until they reach the ovary. POLYANDROUS (flowers).--Flowers having many stamens. POLYGAMOUS PLANTS.--Plants in which some flowers are unisexual and others hermaphrodite. The unisexual (male and female) flowers, may be on the same or on different plants. POLYMORPHIC.--Presenting many forms. POLYZOARY.--The common structure formed by the cells of the Polyzoa, such as the well-known seamats. PREHENSILE.--Capable of grasping. PREPOTENT.--Having a superiority of power. PRIMARIES.--The feathers forming the tip of the wing of a bird, and inserted upon that part which represents the hand of man. PROCESSES.--Projecting portions of bones, usually for the attachment of muscles, ligaments, etc. PROPOLIS.--A resinous material collected by the hivebees from the opening buds of various trees. PROTEAN.--Exceedingly variable. PROTOZOA.--The lowest great division of the animal kingdom. These animals are composed of a gelatinous material, and show scarcely any trace of distinct organs. The Infusoria, Foraminifera, and sponges, with some other forms, belong to this division. PUPA (pl. PUPAE).--The second stage in the development of an insect, from which it emerges in the perfect (winged) reproductive form. In most insects the PUPAL STAGE is passed in perfect repose. The CHRYSALIS is the pupal state of butterflies. RADICLE.--The minute root of an embryo plant. RAMUS.--One half of the lower jaw in the Mammalia. The portion which rises to articulate with the skull is called the ASCENDING RAMUS. RANGE.--The extent of country over which a plant or animal is naturally spread. RANGE IN TIME expresses the distribution of a species or group through the fossiliferous beds of the earth's crust. RETINA.--The delicate inner coat of the eye, formed by nervous filaments spreading from the optic nerve, and serving for the perception of the impressions produced by light. RETROGRESSION.--Backward development. When an animal, as it approaches maturity, becomes less perfectly organised than might be expected from its early stages and known relationships, it is said to undergo a RETROGRADE DEVELOPMENT or METAMORPHOSIS. RHIZOPODS.--A class of lowly organised animals (Protozoa), having a gelatinous body, the surface of which can be protruded in the form of root-like processes or filaments, which serve for locomotion and the prehension of food. The most important order is that of the Foraminifera. RODENTS.--The gnawing Mammalia, such as the rats, rabbits, and squirrels. They are especially characterised by the possession of a single pair of chisel-like cutting teeth in each jaw, between which and the grinding teeth there is a great gap. RUBUS.--The bramble genus. RUDIMENTARY.--Very imperfectly developed. RUMINANTS.--The group of quadrupeds which ruminate or chew the cud, such as oxen, sheep, and deer. They have divided hoofs, and are destitute of front teeth in the upper jaw. SACRAL.--Belonging to the sacrum, or the bone composed usually of two or more united vertebrae to which the sides of the pelvis in vertebrate animals are attached. SARCODE.--The gelatinous material of which the bodies of the lowest animals (Protozoa) are composed. SCUTELLAE.--The horny plates with which the feet of birds are generally more or less covered, especially in front. SEDIMENTARY FORMATIONS.--Rocks deposited as sediments from water. SEGMENTS.--The transverse rings of which the body of an articulate animal or annelid is composed. SEPALS.--The leaves or segments of the calyx, or outermost envelope of an ordinary flower. They are usually green, but sometimes brightly coloured. SERRATURES.--Teeth like those of a saw. SESSILE.--Not supported on a stem or footstalk. SILURIAN SYSTEM.--A very ancient system of fossiliferous rocks belonging to the earlier part of the Palaeozoic series. SPECIALISATION.--The setting apart of a particular organ for the performance of a particular function. SPINAL CORD.--The central portion of the nervous system in the Vertebrata, which descends from the brain through the arches of the vertebrae, and gives off nearly all the nerves to the various organs of the body. STAMENS.--The male organs of flowering plants, standing in a circle within the petals. They usually consist of a filament and an anther, the anther being the essential part in which the pollen, or fecundating dust, is formed. STERNUM.--The breast-bone. STIGMA.--The apical portion of the pistil in flowering plants. STIPULES.--Small leafy organs placed at the base of the footstalks of the leaves in many plants. STYLE.--The middle portion of the perfect pistil, which rises like a column from the ovary and supports the stigma at its summit. SUBCUTANEOUS.--Situated beneath the skin. SUCTORIAL.--Adapted for sucking. SUTURES (in the skull).--The lines of junction of the bones of which the skull is composed. TARSUS (pl. TARSI).--The jointed feet of articulate animals, such as insects. TELEOSTEAN FISHES.--Fishes of the kind familiar to us in the present day, having the skeleton usually completely ossified and the scales horny. TENTACULA or TENTACLES.--Delicate fleshy organs of prehension or touch possessed by many of the lower animals. TERTIARY.--The latest geological epoch, immediately preceding the establishment of the present order of things. TRACHEA.--The windpipe or passage for the admission of air to the lungs. TRIDACTYLE.--Three-fingered, or composed of three movable parts attached to a common base. TRILOBITES.--A peculiar group of extinct crustaceans, somewhat resembling the woodlice in external form, and, like some of them, capable of rolling themselves up into a ball. Their remains are found only in the Palaeozoic rocks, and most abundantly in those of Silurian age. TRIMORPHIC.--Presenting three distinct forms. UMBELLIFERAE.--An order of plants in which the flowers, which contain five stamens and a pistil with two styles, are supported upon footstalks which spring from the top of the flower stem and spread out like the wires of an umbrella, so as to bring all the flowers in the same head (UMBEL) nearly to the same level. (Examples, parsley and carrot.) UNGULATA.--Hoofed quadrupeds. UNICELLULAR.--Consisting of a single cell. VASCULAR.--Containing blood-vessels. VERMIFORM.--Like a worm. VERTEBRATA or VERTEBRATE ANIMALS.--The highest division of the animal kingdom, so called from the presence in most cases of a backbone composed of numerous joints or VERTEBRAE, which constitutes the centre of the skeleton and at the same time supports and protects the central parts of the nervous system. WHORLS.--The circles or spiral lines in which the parts of plants are arranged upon the axis of growth. WORKERS.--See neuters. ZOEA-STAGE.--The earliest stage in the development of many of the higher Crustacea, so called from the name of ZOEA applied to these young animals when they were supposed to constitute a peculiar genus. ZOOIDS.--In many of the lower animals (such as the Corals, Medusae, etc.) reproduction takes place in two ways, namely, by means of eggs and by a process of budding with or without separation from the parent of the product of the latter, which is often very different from that of the egg. The individuality of the species is represented by the whole of the form produced between two sexual reproductions; and these forms, which are apparently individual animals, have been called ZOOIDE. INDEX. Aberrant groups Abyssinia, plants of Acclimatisation Adoxa Affinities of extinct species --of organic beings Agassiz on Amblyopsis --on groups of species suddenly appearing --on prophetic forms --on embryological succession --on the Glacial period --on embryological characters --on the latest tertiary forms --on parallelism of embryological development and geological succession --Alex., on pedicellariae Algae of New Zealand Alligators, males, fighting Alternate generations Amblyopsis, blind fish America, North, productions allied to those of Europe --boulders and glaciers of --South, no modern formations on west coast Ammonites, sudden extinction of Anagallis, sterility of Analogy of variations Andaman Islands inhabited by a toad Ancylus Animals, not domesticated from being variable --domestic; descended from several stocks --acclimatisation of Animals of Australia --with thicker fur in cold climates --blind, in caves --extinct, of Australia Anomma Antarctic islands, ancient flora of Antechinus Ants attending aphides --slave-making instinct --neuters, structure of Apes, not having acquired intellectual powers Aphides attended by ants Aphis, development of Apteryx Arab horses Aralo-Caspian Sea Archeopteryx Archiac, M. de, on the succession of species Artichoke, Jerusalem Ascension, plants of Asclepias, pollen of Asparagus Aspicarpa Asses, striped --improved by selection Ateuchus Aucapitaine, on land-shells Audubon, on habits of frigate-bird --on variation in birds' nests --on heron eating seeds Australia, animals of --dogs of --extinct animals of --European plants in --glaciers of Azara, on flies destroying cattle Azores, flora of Babington, Mr., on British plants Baer, Von, standard of Highness --comparison of bee and fish --embryonic similarity of the Vertebrata Baker, Sir S., on the giraffe Balancement of growth Baleen Barberry, flowers of Barrande, M., on Silurian colonies --on the succession of species --on parallelism of palaeozoic formations --on affinities of ancient species Barriers, importance of Bates, Mr., on mimetic butterflies Batrachians on islands Bats, how structure acquired --distribution of Bear, catching water-insects Beauty, how acquired Bee, sting of --queen, killing rivals --Australian, extermination of Bees, fertilizing flowers --hive, not sucking the red clover --hive, cell-making instinct --Ligurian --variation in habits Bees, parasitic --humble, cells of Beetles, wingless, in Madeira --with deficient tarsi Bentham, Mr., on British plants --on classification Berkeley, Mr., on seeds in salt-water Bermuda, birds of Birds acquiring fear --beauty of --annually cross the Atlantic --colour of, on continents --footsteps, and remains of, in secondary rocks --fossil, in caves of Brazil --of Madeira, Bermuda, and Galapagos --song of males --transporting seeds --waders --wingless Bizcacha, affinities of Bladder for swimming, in fish Blindness of cave animals Blyth, Mr., on distinctness of Indian cattle --on striped Hemionus --on crossed geese Borrow, Mr., on the Spanish pointer Bory St. Vincent, on Batrachians Bosquet, M., on fossil Chthamalus Boulders, erratic, on the Azores Branchiae --of crustaceans Braun, Prof., on the seeds of Fumariaceae Brent, Mr., on house-tumblers Britain, mammals of Broca, Prof., on Natural Selection Bronn, Prof., on duration of specific forms --various objections by Brown, Robert, on classification Brown-Sequard, on inherited mutilations Busk, Mr., on the Polyzoa Butterflies, mimetic Buzareingues, on sterility of varieties Cabbage, varieties of, crossed Calceolaria Canary-birds, sterility of hybrids Cape de Verde Islands, productions of --plants of, on mountains Cape of Good Hope, plants of Carpenter, Dr., on foraminifera Carthemus Catasetum Cats, with blue eyes, deaf --variation in habits of --curling tail when going to spring Cattle destroying fir-trees --destroyed by flies in Paraguay --breeds of, locally extinct --fertility of Indian and European breeds --Indian Cave, inhabitants of, blind Cecidomyia Celts, proving antiquity of man Centres of creation Cephalopodae, structures of eyes --development of Cercopithecus, tail of Ceroxylus laceratus Cervulus Cetacea, teeth and hair --development of the whalebone Cetaceans Ceylon, plants of Chalk formation Characters, divergence of --sexual, variable --adaptive or analogical Charlock Checks to increase --mutual Chelae of Crustaceans Chickens, instinctive tameness of Chironomus, its asexual reproduction Chthamalinae Chthamalus, cretacean species of Circumstances favourable to selection of domestic products --to natural selection Cirripedes capable of crossing --carapace aborted --their ovigerous frena --fossil --larvae of Claparede, Prof., on the hair-claspers of the Acaridae Clarke, Rev. W.B., on old glaciers in Australia Classification Clift, Mr., on the succession of types Climate, effects of, in checking increase of beings --adaptation of, to organisms Climbing plants --development of Clover visited by bees Cobites, intestine of Cockroach Collections, palaeontological, poor Colour, influenced by climate --in relation to attacks by flies Columba livia, parent of domestic pigeons Colymbetes Compensation of growth Compositae, flowers and seeds of --outer and inner florets of --male flowers of Conclusion, general Conditions, slight changes in, favourable to fertility Convergence of genera Coot Cope, Prof., on the acceleration or retardation of the period of reproduction Coral-islands, seeds drifted to --reefs, indicating movements of earth Corn-crake Correlated variation in domestic productions Coryanthes Creation, single centres of Crinum Croll, Mr., on subaerial denudation --on the age of our oldest formations --on alternate Glacial periods in the North and South Crosses, reciprocal Crossing of domestic animals, importance in altering breeds --advantages of --unfavourable to selection Cruger, Dr., on Coryanthes Crustacea of New Zealand Crustacean, blind air-breathers Crustaceans, their chelae Cryptocerus Ctenomys, blind Cuckoo, instinct of Cunningham, Mr., on the flight of the logger-headed duck Currants, grafts of Currents of sea, rate of Cuvier on conditions of existence --on fossil monkeys Cuvier, Fred., on instinct Cyclostoma, resisting salt water Dana, Prof., on blind cave-animals --on relations of crustaceans of Japan --on crustaceans of New Zealand Dawson, Dr., on eozoon De Candolle, Aug. Pyr., on struggle for existence --on umbelliferae --on general affinities De Candolle, Alph., on the variability of oaks --on low plants, widely dispersed --on widely-ranging plants being variable --on naturalisation --on winged seeds --on Alpine species suddenly becoming rare --on distribution of plants with large seeds --on vegetation of Australia --on fresh-water plants --on insular plants Degradation of rocks Denudation, rate of --of oldest rocks --of granite areas Development of ancient forms Devonian system Dianthus, fertility of crosses Dimorphism in plants Dirt on feet of birds Dispersal, means of --during Glacial period Distribution, geographical --means of Disuse, effect of, under nature Diversification of means for same general purpose Division, physiological, of labour Divergence of character Dog, resemblance of jaw to that of the Thylacinus Dogs, hairless, with imperfect teeth --descended from several wild stocks --domestic instincts of --inherited civilisation of --fertility of breeds together --of crosses --proportions of body in different breeds, when young Domestication, variation under Double flowers Downing, Mr., on fruit-trees in America Dragon-flies, intestines of Drift-timber Driver-ant Drones killed by other bees Duck, domestic, wings of, reduced --beak of --logger-headed Duckweed Dugong, affinities of Dung-beetles with deficient tarsi Dyticus Earl, Mr., W., on the Malay Archipelago Ears, drooping, in domestic animals --rudimentary Earth, seeds in roots of trees --charged with seeds Echinodermata, their pedicellariae Eciton Economy of organisation Edentata, teeth and hair --fossil species of Edwards, Milne, on physiological division of labour --on gradations of structure Edwards, on embryological characters Eggs, young birds escaping from Egypt, productions of, not modified Electric organs Elephant, rate of increase --of Glacial period Embryology Eozoon Canadense Epilipsy inherited Existence, struggle for --condition of Extinction, as bearing on natural selection --of domestic varieties Eye, structure of --correction for aberration Eyes, reduced, in moles Fabre, M., on hymenoptera fighting --on parasitic sphex --on Sitaris Falconer, Dr., on naturalisation of plants in India --on elephants and mastodons --and Cautley on mammals of sub-Himalayan beds Falkland Islands, wolf of Faults Faunas, marine Fear, instinctive, in birds Feet of birds, young molluscs adhering to Fertilisation variously effected Fertility of hybrids --from slight changes in conditions --of crossed varieties Fir-trees destroyed by cattle --pollen of Fish, flying --teleostean, sudden appearance of --eating seeds --fresh-water, distribution of Fishes, ganoid, now confined to fresh water --ganoid, living in fresh water --electric organs of --of southern hemisphere Flight, powers of, how acquired Flint-tools, proving antiquity of man Flower, Prof., on the larynx --on Halitherium --on the resemblance between the jaws of the dog and Thylacinus --on the homology of the feet of certain marsupials Flowers, structure of --in relation to crossing --of composite and umbelliferae --beauty of --double Flysch formation, destitute of organic remains Forbes, Mr. D., on glacial action in the Andes Forbes, E., on colours of shells --on abrupt range of shells in depth --on poorness of palaeontological collections --on continuous succession of genera --on continental extensions --on distribution during Glacial period --on parallelism in time and space Forests, changes in, in America Formation, Devonian --Cambrian --intermittent --thickness of, in Britain Formica --rufescens --sanguinea --flava, neuter of Forms, lowly organised, long enduring Frena, ovigerous, of cirripedes Fresh-water productions, dispersal of Fries on species in large genera being closely allied to other species Frigate-bird Frogs on islands Fruit-trees, gradual improvement of --in United States --varieties of, acclimatised in United States Fuci, crossed Fur, thicker in cold climates Furze Galapagos Archipelago, birds of --productions of Galaxias, its wide range Galeopithecus Game, increase of, checked by vermin Gartner on sterility of hybrids --on reciprocal crosses --on crossed maize and verbascum --on comparison of hybrids and mongrels Gaudry, Prof., on intermediate genera of fossil mammals in Attica Geese, fertility when crossed --upland Geikie, Mr., on subaerial denudation Genealogy, important in classification Generations, alternate Geoffroy St. Hilaire, on balancement --on homologous organs Geoffroy St. Hilaire, Isidore, on variability of repeated parts --on correlation, in monstrosities --on correlation --on variable parts being often monstrous Geographical distribution Geography, ancient Geology, future progress of --imperfection of the record Gervais, Prof., on Typotherium Giraffe, tail of --structure of Glacial period --affecting the North and South Glands, mammary Gmelin, on distribution Godwin-Austin, Mr., on the Malay Archipelago Goethe, on compensation of growth Gomphia Gooseberry, grafts of Gould, Dr. Aug. A., on land-shells Gould, Mr., on colours of birds --on instincts of cuckoo --on distribution of genera of birds Gourds, crossed Graba, on the Uria lacrymans Grafting, capacity of Granite, areas of denuded Grasses, varieties of Gray, Dr. Asa, on the variability of oaks --on man not causing variability --on sexes of the holly --on trees of the United States --on naturalised plants in the United States --on aestivation --on rarity of intermediate varieties --on Alpine plants Gray, Dr. J.E., on striped mule Grebe Grimm, on asexual reproduction Groups, aberrant Grouse, colours of --red, a doubtful species Growth, compensation of Gunther, Dr., on flat-fish --on prehensile tails --on the fishes of Panama --on the range of fresh-water fishes --on the limbs of Lepidosiren Haast, Dr., on glaciers of New Zealand Habit, effect of, under domestication --effect of, under nature --diversified, of same species Hackel, Prof., on classification and the lines of descent Hair and teeth, correlated Halitherium Harcourt, Mr. E.V., on the birds of Madeira Hartung, M., on boulders in the Azores Hazel-nuts Hearne, on habits of bears Heath, changes in vegetation Hector, Dr., on glaciers of New Zealand Heer, Oswald, on ancient cultivated plants --on plants of Madeira Helianthemum Helix pomatia, resisting salt water Helmholtz, M., on the imperfection of the human eye Helosciadium Hemionus, striped Hensen, Dr., on the eyes of Cephalopods Herbert, W., on struggle for existence --on sterility of hybrids Hermaphrodites crossing Heron eating seed Heron, Sir R., on peacocks Heusinger, on white animals poisoned by certain plants Hewitt, Mr., on sterility of first crosses Hildebrand, Prof., on the self-sterility of Corydalis Hilgendorf, on intermediate varieties Himalaya, glaciers of --plants of Hippeastrum Hippocampus Hofmeister, Prof., on the movements of plants Holly-trees, sexes of Hooker, Dr., on trees of New Zealand --on acclimatisation of Himalayan trees --on flowers of umbelliferae --on the position of ovules --on glaciers of Himalaya --on algae of New Zealand --on vegetation at the base of the Himalaya --on plants of Tierra del Fuego --on Australian plants --on relations of flora of America --on flora of the Antarctic lands --on the plants of the Galapagos --on glaciers of the Lebanon --on man not causing variability --on plants of mountains of Fernando Po Hooks on palms --on seeds, on islands Hopkins, Mr., on denudation Hornbill, remarkable instinct of Horns, rudimentary Horse, fossil in La Plata --proportions of, when young Horses destroyed by flies in Paraguay --striped Horticulturists, selection applied by Huber on cells of bees Huber, P., on reason blended with instinct --on habitual nature of instincts --on slave-making ants --on Melipona domestica Hudson, Mr., on the Ground-woodpecker of La Plata --on the Molothrus Humble-bees, cells of Hunter, J., on secondary sexual characters Hutton, Captain, on crossed geese Huxley, Prof., on structure of hermaphrodites --on the affinities of the Sirenia --on forms connecting birds and reptiles --on homologous organs --on the development of aphis Hybrids and mongrels compared Hybridism Hydra, structure of Hymenoptera, fighting Hymenopterous insect, diving Hyoseris Ibla Icebergs transporting seeds Increase, rate of Individuals, numbers favourable to selection --many, whether simultaneously created Inheritance, laws of --at corresponding ages Insects, colour of, fitted for their stations --sea-side, colours of --blind, in caves --luminous --their resemblance to certain objects --neuter Instinct, not varying simultaneously with structure Instincts, domestic Intercrossing, advantages of Islands, oceanic Isolation favourable to selection Japan, productions of Java, plants of Jones, Mr. J.M., on the birds of Bermuda Jordain, M., on the eye-spots of star fishes Jukes, Prof., on subaerial denudation Jussieu on classification Kentucky, caves of Kerguelen-land, flora of Kidney-bean, acclimatisation of Kidneys of birds Kirby, on tarsi deficient in beetles Knight, Andrew, on cause of variation Kolreuter, on intercrossing --on the barberry --on sterility of hybrids --on reciprocal crosses --on crossed varieties of nicotiana --on crossing male and hermaphrodite flowers Lamarck, on adaptive characters Lancelet, eyes of Landois, on the development of the wings of insects Land-shells, distribution of --of Madeira, naturalised --resisting salt water Languages, classification of Lankester, Mr. E. Ray, on longevity --on homologies Lapse, great, of time Larvae Laurel, nectar secreted by the leaves Laurentian formation Laws of variation Leech, varieties of Leguminosae, nectar secreted by glands Leibnitz, attack on Newton Lepidosiren, limbs in a nascent condition Lewes, Mr. G.H., on species not having changed in Egypt --on the Salamandra atra --on many forms of life having been at first evolved Life, struggle for Lingula, Silurian Linnaeus, aphorism of Lion, mane of --young of, striped Lobelia fulgens Lobelia, sterility of crosses Lockwood, Mr., on the ova of the Hippocampus Locusts transporting seeds Logan, Sir W., on Laurentian formation Lowe, Rev. R.T., on locusts visiting Madeira Lowness, of structure connected with variability --related to wide distribution Lubbock, Sir J., on the nerves of coccus --on secondary sexual characters --on a diving hymenopterous insect --on affinities --on metamorphoses Lucas, Dr. P., on inheritance --on resemblance of child to parent Lund and Clausen, on fossils of Brazil Lyell, Sir C., on the struggle for existence --on modern changes of the earth --on terrestrial animals not having been developed on islands --on a carboniferous land-shell --on strata beneath Silurian system --on the imperfection of the geological record --on the appearance of species --on Barrande's colonies --on tertiary formations of Europe and North America --on parallelism of tertiary formations --on transport of seeds by icebergs --on great alternations of climate --on the distribution of fresh-water shells --on land-shells of Madeira Lyell and Dawson, on fossilized trees in Nova Scotia Lythrum salicaria, trimorphic Macleay, on analogical characters Macrauchenia McDonnell, Dr., on electric organs Madeira, plants of --beetles of, wingless --fossil land-shells of --birds of Magpie tame in Norway Males, fighting Maize, crossed Malay Archipelago, compared with Europe --mammals of Malm, on flat-fish Malpighiaceae, small imperfect flowers of Mammae, their development --rudimentary Mammals, fossil, in secondary formation --insular Man, origin of Manatee, rudimentary nails of Marsupials, fossil species of Marsupials of Australia, structure of their feet Martens, M., experiment on seeds Martin, Mr. W.C., on striped mules Masters, Dr., on Saponaria Matteucci, on the electric organs of rays Matthiola, reciprocal crosses of Maurandia Means of dispersal Melipona domestica Merrill, Dr., on the American cuckoo Metamorphism of oldest rocks Mice destroying bees --acclimatisation of --tails of Miller, Prof., on the cells of bees Mirabilis, crosses of Missel-thrush Mistletoe, complex relations of Mivart, Mr., on the relation of hair and teeth --on the eyes of cephalopods --various objections to Natural Selection --on abrupt modifications --on the resemblance of the mouse and antechinus Mocking-thrush of the Galapagos Modification of species, not abrupt Moles, blind Molothrus, habits of Mongrels, fertility and sterility of --and hybrids compared Monkeys, fossil Monachanthus Mons, Van, on the origin of fruit-trees Monstrosities Moquin-Tandon, on sea-side plants Morphology Morren, on the leaves of Oxalis Moths, hybrid Mozart, musical powers of Mud, seeds in Mules, striped Muller, Adolph, on the instincts of the cuckoo Muller, Dr. Ferdinand, on Alpine Australian plants Muller, Fritz, on dimorphic crustaceans --on the lancelet --on air-breathing crustaceans --on the self-sterility of orchids --on embryology in relation to classification --on the metamorphoses of crustaceans --on terrestrial and fresh-water organisms not undergoing any metamorphosis --on climbing plants Multiplication of species not indefinite Murchison, Sir, R., on the formations of Russia --on azoic formations --on extinction Murie, Dr., on the modification of the skull in old age Murray, Mr. A., on cave-insects Mustela vison Myanthus Myrmecocystus Myrmica, eyes of Nageli, on morphological characters Nails, rudimentary Nathusius, Von, on pigs Natural history, future progress of --selection --system Naturalisation of forms distinct from the indigenous species --in New Zealand Naudin, on analagous variations in gourds --on hybrid gourds --on reversion Nautilus, Silurian Nectar of plants Nectaries, how formed Nelumbium luteum Nests, variation in Neuter insects New Zealand, productions of, not perfect --naturalised products of --fossil birds of --glaciers of --crustaceans of --algae of --number of plants of --flora of Newman, Col., on humble-bees Newton, Prof., on earth attached to a partridge's foot Newton, Sir I., attacked for irreligion Nicotiana, crossed varieties of --certain species very sterile Nitsche, Dr., on the Polyzoa Noble, Mr., on fertility of Rhododendron Nodules, phosphatic, in azoic rocks Oak, varieties of Onites apelles Orchids, fertilisation of --the development of their flowers --forms of Orchis, pollen of Organisation, tendency to advance Organs of extreme perfection --electric, of fishes --of little importance --homologous --rudiments of, and nascent Ornithorhynchus, mammae of Ostrich not capable of flight --habit of laying eggs together --American, two species of Otter, habits of, how acquired Ouzel, water Owen, Prof., on birds not flying --on vegetative repetition --on variability of unusually developed parts --on the eyes of fishes --on the swim-bladder of fishes --on fossil horse of La Plata --on generalised form --on relation of ruminants and pachyderms --on fossil birds of New Zealand --on succession of types --on affinities of the dugong --on homologous organs --on the metamorphosis of cephalopods Pacific Ocean, faunas of Pacini, on electric organs Paley, on no organ formed to give pain Pallas, on the fertility of the domesticated descendants of wild stocks Palm with hooks Papaver bracteatum Paraguay, cattle destroyed by flies Parasites Partridge, with ball of dirt attached to foot Parts greatly developed, variable Parus major Passiflora Peaches in United States Pear, grafts of Pedicellariae Pelargonium, flowers of --sterility of Peloria Pelvis of women Period, glacial Petrels, habits of Phasianus, fertility of hybrids Pheasant, young, wild Pictet, Prof., on groups of species suddenly appearing --on rate of organic change --on continuous succession of genera --on close alliance of fossils in consecutive formations --on change in latest tertiary forms --on early transitional links Pierce, Mr., on varieties of wolves Pigeons with feathered feet and skin between toes --breeds described, and origin of --breeds of, how produced --tumbler, not being able to get out of egg --reverting to blue colour --instinct of tumbling --young of Pigs, black, not affected by the paint-root --modified by want of exercise Pistil, rudimentary Plants, poisonous, not affecting certain coloured animals --selection, applied to --gradual improvement of --not improved in barbarous countries --dimorphic --destroyed by insects --in midst of range, have to struggle with other plants --nectar of --fleshy, on sea-shores --climbing --fresh-water, distribution of --low in scale, widely distributed Pleuronectidae, their structure Plumage, laws of change in sexes of birds Plums in the United States Pointer dog, origin of --habits of Poison not affecting certain coloured animals Poison, similar effect of, on animals and plants Pollen of fir-trees --transported by various means Pollinia, their development Polyzoa, their avicularia Poole, Col., on striped hemionus Potemogeton Pouchet, on the colours of flat-fish Prestwich, Mr., on English and French eocene formations Proctotrupes Proteolepas Proteus Psychology, future progress of Pyrgoma, found in the chalk Quagga, striped Quatrefages, M., on hybrid moths Quercus, variability of Quince, grafts of Rabbits, disposition of young Races, domestic, characters of Race-horses, Arab --English Radcliffe, Dr., the electrical organs of the torpedo Ramond, on plants of Pyrenees Ramsay, Prof., on subaerial denudation --on thickness of the British formations --on faults Ramsay, Mr., on instincts of cuckoo Ratio of increase Rats, supplanting each other --acclimatisation of --blind, in cave Rattle-snake Reason and instinct Recapitulation, general Reciprocity of crosses Record, geological, imperfect Rengger, on flies destroying cattle Reproduction, rate of Resemblance, protective, of insects --to parents in mongrels and hybrids Reversion, law of inheritance --in pigeons, to blue colour Rhododendron, sterility of Richard, Prof., on Aspicarpa Richardson, Sir J., on structure of squirrels --on fishes of the southern hemisphere Robinia, grafts of Rodents, blind Rogers, Prof., Map of N. America Rudimentary organs Rudiments important for classification Rutimeyer, on Indian cattle Sageret, on grafts Salamandra atra Saliva used in nests Salmons, males fighting, and hooked jaws of Salt-water, how far injurious to seeds --not destructive to land-shells Salter, Mr., on early death of hybrid embryos Salvin, Mr., on the beaks of ducks Saurophagus sulphuratus Schacht, Prof., on Phyllotaxy Schiodte, on blind insects --on flat-fish Schlegel, on snakes Schobl, Dr., on the ears of mice Scott, Mr. J., on the self-sterility of orchids --on the crossing of varieties of verbascum Sea-water, how far injurious to seeds --not destructive to land-shells Sebright, Sir J., on crossed animals Sedgwick, Prof., on groups of species suddenly appearing Seedlings destroyed by insects Seeds, nutriment in --winged --means of dissemination --power of resisting salt-water --in crops and intestines of birds --eaten by fish --in mud --hooked, on islands Selection of domestic products --principle not of recent origin --unconscious --natural --sexual --objections to term --natural, has not induced sterility Sexes, relations of Sexual characters variable --selection Sheep, Merino, their selection --two sub-breeds, unintentionally produced --mountain, varieties of Shells, colours of, littoral --hinges of --seldom embedded Shells, fresh-water, long retain the same forms --fresh-water, dispersal of --of Madeira --land, distribution of --land, resisting salt water Shrew-mouse Silene, infertility of crosses Silliman, Prof., on blind rat Sirenia, their affinities Sitaris, metamorphosis of Skulls of young mammals Slave-making instinct Smith, Col. Hamilton, on striped horses Smith, Dr., on the Polyzoa Smith, Mr. Fred., on slave-making ants --on neuter ants Snake with tooth for cutting through egg-shell Somerville, Lord, on selection of sheep Sorbus, grafts of Sorex Spaniel, King Charles' breed Specialisation of organs Species, polymorphic --dominant --common, variable --in large genera variable --groups of, suddenly appearing --beneath Silurian formations --successively appearing --changing simultaneously throughout the world Spencer, Lord, on increase in size of cattle Spencer, Mr. Herbert, on the first steps in differentiation --on the tendency to an equilibrium in all forces Sphex, parasitic Spiders, development of Sports in plants Sprengel, C.C., on crossing --on ray-florets Squalodon Squirrels, gradations in structure Staffordshire, heath, changes in Stag-beetles, fighting Star fishes, eyes of --their pedicellariae Sterility from changed conditions of life --of hybrids --laws of --causes of --from unfavourable conditions --not induced through natural selection St. Helena, productions of St. Hilaire, Aug., on variability of certain plants --on classification St. John, Mr., on habits of cats Sting of bee Stocks, aboriginal, of domestic animals Strata, thickness of, in Britain Stripes on horses Structure, degrees of utility of Struggle for existence Succession, geological --of types in same areas Swallow, one species supplanting another Swaysland, Mr., on earth adhering to the feet of migratory birds Swifts, nests of Swim-bladder Switzerland, lake inhabitants of System, natural Tail of giraffe --of aquatic animals --prehensile --rudimentary Tanais, dimorphic Tarsi deficient Tausch, Dr., on umbelliferae Teeth and hair correlated --rudimentary, in embryonic calf Tegetmeier, Mr., on cells of bees Temminck, on distribution aiding classification Tendrils, their development Thompson, Sir W., on the age of the habitable world --on the consolidation of the crust of the earth Thouin, on grafts Thrush, aquatic species of --mocking, of the Galapagos --young of, spotted --nest of Thuret, M., on crossed fuci Thwaites, Mr., on acclimatisation Thylacinus Tierra del Fuego, dogs of --plants of Timber-drift Time, lapse of --by itself not causing modification Titmouse Toads on islands Tobacco, crossed varieties of Tomes, Mr., on the distribution of bats Transitions in varieties rare Traquair, Dr., on flat-fish Trautschold, on intermediate varieties Trees on islands belong to peculiar orders --with separated sexes Trifolium pratense --incarnatum Trigonia Trilobites --sudden extinction of Trimen, Mr., on imitating-insects Trimorphism in plants Troglodytes Tuco-tuco, blind Tumbler pigeons, habits of, hereditary --young of Turkey-cock, tuft of hair on breast Turkey, naked skin on head --young of, instinctively wild Turnip and cabbage, analogous variations of Type, unity of Types, succession of, in same areas Typotherium Udders enlarged by use --rudimentary Ulex, young leaves of Umbelliferae, flowers and seeds of --outer and inner florets of Unity of type Uria lacrymans Use, effects of --under domestication --in a state of nature Utility, how far important in the construction of each part Valenciennes, on fresh-water fish Variability of mongrels and hybrids Variation, under domestication --caused by reproductive system being affected by conditions of life --under nature --laws of --correlated Variations appear at corresponding ages --analogous in distinct species Varieties, natural --struggle between --domestic, extinction of --transitional, rarity of Varieties, when crossed --fertile --sterile --classification of Verbascum, sterility of --varieties of, crossed Verlot, M., on double stocks Verneuil, M. de, on the succession of species Vibracula of the Polyzoa Viola, small imperfect flowers of --tricolor Virchow, on the structure of the crystalline lens Virginia, pigs of Volcanic islands, denudation of Vulture, naked skin on head Wading-birds Wagner, Dr., on Cecidomyia Wagner, Moritz, on the importance of isolation Wallace, Mr., on origin of species --on the limit of variation under domestication --on dimorphic lepidoptera --on races in the Malay Archipelago --on the improvement of the eye --on the walking-stick insect --on laws of geographical distribution --on the Malay Archipelago --on mimetic animals Walsh, Mr. B.D., on phytophagic forms --on equal variability Water, fresh, productions of Water-hen Waterhouse, Mr., on Australian marsupials --on greatly developed parts being variable --on the cells of bees --on general affinities Water-ouzel Watson, Mr. H.C., on range of varieties of British plants --on acclimatisation --on flora of Azores --on rarity of intermediate varieties --on Alpine plants --on convergence --on the indefinite multiplication of species Weale, Mr., on locusts transporting seeds Web of feet in water-birds Weismann, Prof., on the causes of variability --on rudimentary organs West Indian islands, mammals of Westwood, on species in large genera being closely allied to others --on the tarsi of Engidae --on the antennae of hymenopterous insects Whales Wheat, varieties of White Mountains, flora of Whittaker, Mr., on lines of escarpment Wichura, Max, on hybrids Wings, reduction of size --of insects homologous with branchiae --rudimentary, in insects Wolf crossed with dog --of Falkland Isles Wollaston, Mr., on varieties of insects --on fossil varieties of shells in Madeira Wollaston, Mr., on colours of insects on sea-shore --on wingless beetles --on rarity of intermediate varieties --on insular insects --on land-shells of Madeira naturalised Wolves, varieties of Woodcock with earth attached to leg Woodpecker, habits of --green colour of Woodward, Mr., on the duration of specific forms --on Pyrgoma --on the continuous succession of genera --on the succession of types World, species changing simultaneously throughout Wright, Mr. Chauncey, on the giraffe --on abrupt modifications Wrens, nest of Wyman, Prof., on correlation of colour and effects of poison --on the cells of the bee Youatt, Mr., on selection --on sub-breeds of sheep --on rudimentary horns in young cattle Zanthoxylon Zebra, stripes on Zeuglodons 
2739	----	MORE LETTERS OF CHARLES DARWIN By Charles Darwin A RECORD OF HIS WORK IN A SERIES OF HITHERTO UNPUBLISHED LETTERS EDITED BY FRANCIS DARWIN, FELLOW OF CHRIST'S COLLEGE, AND A.C. SEWARD, FELLOW OF EMMANUEL COLLEGE, CAMBRIDGE IN TWO VOLUMES Transcriber's Notes: All biographical footnotes appear at the end of Volume II. All other notes by Charles Darwin's editors appear in the text, in brackets () with a Chapter/Note or Letter/Note number. VOLUME I. DEDICATED WITH AFFECTION AND RESPECT, TO SIR JOSEPH HOOKER IN REMEMBRANCE OF HIS LIFELONG FRIENDSHIP WITH CHARLES DARWIN "You will never know how much I owe to you for your constant kindness and encouragement" CHARLES DARWIN TO SIR JOSEPH HOOKER, SEPTEMBER 14, 1862 PREFACE The "Life and Letters of Charles Darwin" was published in 1887. Since that date, through the kindness of various correspondents, additional letters have been received; among them may be mentioned those written by Mr. Darwin to Mr. Belt, Lady Derby, Hugh Falconer, Mr. Francis Galton, Huxley, Lyell, Mr. John Morley, Max Muller, Owen, Lord Playfair, John Scott, Thwaites, Sir William Turner, John Jenner Weir. But the material for our work consisted in chief part of a mass of letters which, for want of space or for other reasons, were not printed in the "Life and Letters." We would draw particular attention to the correspondence with Sir Joseph Hooker. To him Mr. Darwin wrote with complete freedom, and this has given something of a personal charm to the most technical of his letters. There is also much correspondence, hardly inferior in biographical interest, with Sir Charles Lyell, Fritz Muller, Mr. Huxley, and Mr. Wallace. From this unused material we have been able to compile an almost complete record of Mr. Darwin's work in a series of letters now published for the first time. We have, however, in a few instances, repeated paragraphs, or in one or two cases whole letters, from the "Life and Letters," where such repetition seemed necessary for the sake of clearness or continuity. Our two volumes contain practically all the matter that it now seems desirable to publish. But at some future time others may find interesting data in what remains unprinted; this is certainly true of a short series of letters dealing with the Cirripedes, which are omitted solely for want of space. (Preface/1. Those addressed to the late Albany Hancock have already appeared in the "Transactions of the Tyneside Nat. Field Club," VIII., page 250.) We are fortunate in being permitted, by Sir Joseph Hooker and by Mr. Wallace, to publish certain letters from them to Mr. Darwin. We have also been able to give a few letters from Sir Charles Lyell, Hugh Falconer, Edward Forbes, Dr. Asa Gray, Professor Hyatt, Fritz Muller, Mr. Francis Galton, and Sir T. Lauder Brunton. To the two last named, also to Mrs. Lyell (the biographer of Sir Charles), Mrs. Asa Gray and Mrs. Hyatt, we desire to express our grateful acknowledgments. The present volumes have been prepared, so as to give as full an idea as possible of the course of Mr. Darwin's work. The volumes therefore necessarily contain many letters of a highly technical character, but none, we hope, which are not essentially interesting. With a view to saving space, we have confined ourselves to elucidating the letters by full annotations, and have for the same reason--though with some regret--omitted in most cases the beginnings and endings of the letters. For the main facts of Mr. Darwin's life, we refer our readers to the abstract of his private Diary, given in the present volume. Mr. Darwin generally wrote his letters when he was tired or hurried, and this often led to the omission of words. We have usually inserted the articles, and this without any indication of their absence in the originals. Where there seemed any possibility of producing an alteration of meaning (and in many cases where there is no such possibility) we have placed the introduced words in square brackets. We may say once for all that throughout the book square brackets indicate words not found in the originals. (Preface/2. Except in a few places where brackets are used to indicate passages previously published. In all such cases the meaning of the symbol is explained.) Dots indicate omissions, but many omissions are made without being so indicated. The selection and arrangement of the letters have not been easy. Our plan has been to classify the letters according to subject--into such as deal with Evolution, Geographical Distribution, Botany, etc., and in each group to place the letters chronologically. But in several of the chapters we have adopted sectional headings, which we believe will be a help to the reader. The great difficulty lay in deciding in which of the chief groups a given letter should be placed. If the MS. had been cut up into paragraphs, there would have been no such difficulty; but we feel strongly that a letter should as far as possible be treated as a whole. We have in fact allowed this principle to interfere with an accurate classification, so that the reader will find, for instance, in the chapters on Evolution, questions considered which might equally well have come under Geographical Distribution or Geology, or questions in the chapter on Man which might have been placed under the heading Evolution. In the same way, to avoid mutilation, we have allowed references to one branch of science to remain in letters mainly concerned with another subject. For these irregularities we must ask the reader's patience, and beg him to believe that some pains have been devoted to arrangement. Mr. Darwin, who was careful in other things, generally omitted the date in familiar correspondence, and it is often only by treating a letter as a detective studies a crime that we can make sure of its date. Fortunately, however, Sir Joseph Hooker and others of Darwin's correspondents were accustomed to add the date on which the letters were received. This sometimes leads to an inaccuracy which needs a word of explanation. Thus a letter which Mr. Darwin dated "Wednesday" might be headed by us "Wednesday [January 3rd, 1867]," the latter half being the date on which the letter was received; if it had been dated by the writer it would have been "Wednesday, January 2nd, 1867." In thanking those friends--especially Sir Joseph Hooker and Mr. Wallace--who have looked through some of our proof-sheets, we wish to make it clear that they are not in the smallest degree responsible for our errors or omissions; the weight of our shortcomings rests on us alone. We desire to express our gratitude to those who have so readily supplied us with information, especially to Sir Joseph Hooker, Professor Judd, Professor Newton, Dr. Sharp, Mr. Herbert Spencer, and Mr. Wallace. And we have pleasure in mentioning Mr. H.W. Rutherford, of the University Library, to whose conscientious work as a copyist we are much indebted. Finally, it is a pleasure to express our obligation to those who have helped us in the matter of illustrations. The portraits of Dr. Asa Gray, Mr. Huxley, Sir Charles Lyell, Mr. Romanes, are from their respective Biographies, and for permission to make use of them we have to thank Mrs. Gray, Mr. L. Huxley, Mrs. Lyell, and Mrs. Romanes, as well as the publishers of the books in question. For the reproduction of the early portrait of Mr. Darwin we are indebted to Miss Wedgwood; for the interesting portraits of Hugh Falconer and Edward Forbes we have to thank Mr. Irvine Smith, who obtained for us the negatives; these being of paper, and nearly sixty years old, rendered their reproduction a work of some difficulty. We also thank Messrs. Elliott & Fry for very kindly placing at our disposal a negative of the fine portrait, which forms the frontispiece to Volume II. For the opportunity of making facsimiles of diagrams in certain of the letters, we are once more indebted to Sir Joseph Hooker, who has most generously given the original letters to Mr. Darwin's family. Cambridge, October, 1902. TABLE OF CONTENTS. CONTENTS OF VOLUME I. Outline of Charles Darwin's Life, etc. CHAPTER 1.I.--An Autobiographical Fragment, and Early Letters, 1809-1842. CHAPTER 1.II.--Evolution, 1844-1858. CHAPTER 1.III.--Evolution, 1859-1863. CHAPTER 1.IV.--Evolution, 1864-1869. CHAPTER 1.V.--Evolution, 1870-1882. CHAPTER 1.VI.--Geographical Distribution, 1843-1867. ILLUSTRATIONS IN VOLUME I. CHARLES AND CATHERINE DARWIN, 1816. From a coloured chalk drawing by Sharples, in possession of Miss Wedgwood, of Leith Hill Place. MRS. DARWIN, 1881. From a photograph by Barraud. EDWARD FORBES, 1844 (?). From a photograph by Hill & Adamson. THOMAS HENRY HUXLEY, 1857. From a photograph by Maull & Fox. (Huxley's "Life," Volume I.) PROFESSOR HENSLOW. From a photograph. HUGH FALCONER, 1844. From a photograph by Hill & Adamson. JOSEPH DALTON HOOKER, 1870 (?). From a photograph by Wallich. ASA GRAY, 1867. From a photograph. ("Letters of Asa Gray," Volume I.) VOLUME II CHAPTER 2.VII.--Geographical Distribution, 1867-1882. CHAPTER 2.VIII.--Man, 1860-1882. 2.VIII.I. Descent of Man, 1860-1882. 2.VIII.II. Sexual Selection, 1866-1872. 2.VIII.III. Expression, 1868-1874. CHAPTER 2.IX.--Geology, 1840-1882. 2.IX.I. Vulcanicity and Earth-movements, 1840-1881. 2.IX.II. Ice-action, 1841-1882. 2.IX.III. The Parallel Roads of Glen Roy, 1841-1880. 2.IX.IV. Coral Reefs, Fossil and Recent, 1841-1881. 2.IX.V. Cleavage and Foliation, 1846-1856. 2.IX.VI. Age of the World, 1868-1877. 2.IX.VII. Geological Action of Earth-worms, 1880-1882. 2.IX.VIII. Miscellaneous, 1846-1878. CHAPTER 2.X.--Botany, 1843-1871. 2.X.I. Miscellaneous, 1843-1862. 2.X.II. Melastomaceae, 1862-1881. 2.X.III. Correspondence with John Scott, 1862-1871. CHAPTER 2.XI.--Botany, 1863-1881. 2.XI.I. Miscellaneous, 1863-1866. 2.XI.II. Correspondence with Fritz Muller, 1865-1881. 2.XI.III. Miscellaneous, 1868-1881. CHAPTER 2.XII.--Vivisection and Miscellaneous Subjects, 1867-1882. 2.XII.I. Vivisection, 1875-1882. 2.XII.II. Miscellaneous Subjects, 1867-1882. ILLUSTRATIONS IN VOLUME II. CHARLES DARWIN, 1881. From a photograph by Elliott & Fry. ALFRED RUSSEL WALLACE, 1878. From a photograph by Maull & Fox. GEORGE J. ROMANES, 1891. From a photograph by Elliott & Fry. (Romanes' "Life.") CHARLES LYELL. From a photograph by Maull & Fox. (Lyell's "Life," Volume II.) CHARLES DARWIN, 1854 (?). From a photograph by Maull & Fox. FRITZ MULLER. From a photograph. FACSIMILES OF SKETCHES IN THE LETTERS. FIGURE 1. Hypothetical Section Illustrating Continental Elevation. FIGURE 2. Diagram of Junction between Dike and Lava. FIGURE 3. Outline of an Elliptic Crater. FIGURE 4. Hypothetical Section showing the Relation of Dikes to Volcanic Vents. FIGURE 5. Map illustrating the Linear Arrangement of Volcanic Islands in relation to Continental Coast-lines. FIGURE 6. Sketch showing the Form and Distribution of Quartz in a Foliated Rock. FIGURE 7. Sketch showing the Arrangement of Felspar and Quartz in a Metamorphic Series. FIGURE 8. Floral Diagram of an Orchid. FIGURE 9. Dissected Flower of Habenaria Chlorantha. FIGURE 10. Diagram of a Cruciferous Flower. FIGURE 11. Longitudinal Section of a Cruciferous Flower. FIGURE 12. Transverse Section of the Ovary of a Crucifer. FIGURE 13. (Contents/1. Not a facsimile.) Leaf of Trifolium resupinatum. (Drawn by Miss Pertz.) MORE LETTERS OF CHARLES DARWIN. VOLUME I. OUTLINE OF CHARLES DARWIN'S LIFE. BASED ON HIS DIARY, DATED AUGUST 1838. References to the Journals in which Mr. Darwin's papers were published will be found in his "Life and Letters" III., Appendix II. We are greatly indebted to Mr. C.F. Cox, of New York, for calling our attention to mistakes in the Appendix, and we take this opportunity of correcting them. Appendix II., List ii.--Mr. Romanes spoke on Mr. Darwin's essay on Instinct at a meeting of the Linnean Society, December 6th, 1883, and some account of it is given in "Nature" of the same date. But it was not published by the Linnean Society. Appendix II., List iii.--"Origin of saliferous deposits. Salt lakes of Patagonia and La Plata" (1838). This is the heading of an extract from Darwin's volume on South America reprinted in the "Quarterly Journal of the Geological Society," Volume II., Part ii., "Miscellanea," pages 127-8, 1846. The paper on "Analogy of the Structure of some Volcanic Rocks, etc." was published in 1845, not in 1851. A paper "On the Fertilisation of British Orchids by Insect Agency," in the "Entomologist's Weekly Intelligencer" viii., and "Gardeners' Chronicle," June 9th, 1860, should be inserted in the bibliography. 1809. February 12th: Born at Shrewsbury. 1817. Death of his mother. 1818. Went to Shrewsbury School. 1825. Left Shrewsbury School. 1826. October: Went to Edinburgh University. Read two papers before the Plinian Society of Edinburgh "at the close of 1826 or early in 1827." 1827. Entered at Christ's College, Cambridge. 1828. Began residence at Cambridge. 1831. January: Passed his examination for B.A., and kept the two following terms. August: Geological tour with Sedgwick. September 11th: Went to Plymouth to see the "Beagle." October 2nd: "Took leave of my home." December 27th: "Sailed from England on our circumnavigation." 1832. January 16th: "First landed on a tropical shore" (Santiago). 1833. December 6th: "Sailed for last time from Rio Plata." 1834. June 10th: "Sailed for last time from Tierra del Fuego." 1835. September 5th: "Sailed from west shores of South America." November 16th: Letters to Professor Henslow, read at a meeting of the Cambridge Philosophical Society. November 18th: Paper read before the Geological Society on Notes made during a Survey of the East and West Coasts of South America in years 1832-35. 1836. May 31st: Anchored at the Cape of Good Hope. October 2nd: Anchored at Falmouth. October 4th: Reached Shrewsbury after an absence of five years and two days. December 13th: Went to live at Cambridge. 1837. January 4th: Paper on Recent Elevation in Chili read. March 13th: Settled at 36, Great Marlborough Street. March 14th: Paper on "Rhea" read. May: Read papers on Coral Formation, and on the Pampas, to the Geological Society. July: Opened first note-book on Transmutation of Species. March 13th to November: Occupied with his Journal. October and November: Preparing the scheme for the Zoology of the Voyage of the "Beagle." Working at Geology of South America. November 1st: Read the paper on Earthworms before the Geological Society. 1838. Worked at the Geology of South America and Zoology of Voyage. "Some little species theory." March 7th: Read paper on the Connexion of certain Volcanic Phenomena and on the Formation of Mountain Chains, to the Geological Society. May: Health began to break down. June 23rd: Started for Glen Roy. The paper on Glen Roy was written in August and September. October 5th: Began Coral paper. November 11th: Engaged to be married to his cousin, Emma Wedgwood. December 31st: "Entered 12 Upper Gower Street." 1839. January 29th: Married at Maer. February and March: Some work on Corals and on Species Theory. March (part) and April: Working at Coral paper. Papers on a Rock seen on an Iceberg, and on the Parallel Roads of Glen Roy. Published "Journal and Remarks," being volume iii. of the "Narrative of the Surveying Voyages of H.M.S. 'Adventure' and 'Beagle,' etc." For the rest of the year, Corals and Zoology of the Voyage. Publication of the "Zoology of the Voyage of H.M.S. 'Beagle,'" Part II. (Mammalia). 1840. Worked at Corals and the Zoology of the Voyage. Contributed Geological introduction to Part I. of the "Zoology of the Voyage" (Fossil Mammalia by Owen). 1841. Publication of Part III. of the "Zoology of the Voyage" (Birds). Read paper on Boulders and Glacial Deposits of South America, to Geological Society. Published paper on a remarkable bar of Sandstone off Pernambuco, on the coast of Brazil. Publication of Part IV. of "Zoology of the Voyage" (Fish). 1842. May 6th: Last proof of the Coral book corrected. June: Examined Glacier action in Wales. "Wrote pencil sketch of my Species Theory." July: Wrote paper on Glaciers of Caernarvonshire. October: Began his book on Volcanic Islands. 1843. Working at "Volcanic Islands" and "some Species work." 1844. February 13th: Finished "Volcanic Islands." July to September: Wrote an enlarged version of Species Theory. Papers on Sagitta, and on Planaria. July 27th: Began his book on the Geology of South America. 1845. Paper on the Analogy of the Structure of Volcanic Rocks with that of Glaciers. "Proc. R. Soc. Edin." April 25th to August 25th: Working at second edition of "Naturalist's Voyage." 1846. October 1st: Finished last proof of "Geological Observations on South America." Papers on Atlantic Dust, and on Geology of Falkland Islands, communicated to the Geological Society. Paper on Arthrobalanus. 1847. Working at Cirripedes. Review of Waterhouse's "Natural History of the Mammalia." 1848. March 20th: Finished Scientific Instructions in Geology for the Admiralty Manual. Working at Cirripedes. Paper on Erratic Boulders. 1849. Health especially bad. Working at Cirripedes. March-June: Water-cure at Malvern. 1850. Working at Cirripedes. Published Monographs of Recent and Fossil Lepadidae. 1852. Working at Cirripedes. 1853. November 30th: "Royal Medal given to me." 1854. Published Monographs on Recent and on Fossil Balanidae and Verrucidae. September 9th: Finished packing up all my Cirripedes. "Began sorting notes for Species Theory." 1855. March-April: Experiments on the effect of salt water on seeds. Papers on Icebergs and on Vitality of Seeds. 1856. May 14th: "Began, by Lyell's advice, writing Species Sketch" (described in "Life and Letters" as the "Unfinished Book"). December 16th: Finished Chapter III. Paper read to Linnean Society, On Sea-water and the Germination of Seeds. 1857. September 29th: Finished Chapters VII. and VIII. September 30th to December 29th: Working on Hybridism. Paper on the Agency of Bees in the Fertilisation of Papilionaceous Flowers. 1858. March 9th: "Finished Instinct chapter." June 18th: Received Mr. Wallace's sketch of his evolutionary theory. July 1st: Joint paper of Darwin and Wallace read at the Linnean Society. July 20th to July 27th: "Began Abstract of Species book," i.e., the "Origin of Species," at Sandown, I.W. Paper on Bees and Fertilisation of Flowers. 1859. May 25th: Began proof-sheets of the "Origin of Species." November 24th: Publication of the "Origin": 1250 copies printed. October 2nd to December 9th: At the water-cure establishment, Ilkley, Yorkshire. 1860. January 7th: Publication of Edition II. of "Origin" (3000 copies). January 9th: "Looking over MS. on Variation." Paper on the Fertilisation of British Orchids. July and again in September: Made observations on Drosera. Paper on Moths and Flowers. Publication of "A Naturalist's Voyage." 1861. Up to July at work on "Variation under Domestication." April 30th: Publication of Edition III. of "Origin" (2000 copies). July to the end of year: At work on Orchids. November: Primula paper read at Linnean Society. Papers on Pumilio and on Fertilisation of Vinca. 1862. May 15th: Orchid book published. Working at Variation. Paper on Catasetum (Linnean Society). Contribution to Chapter III. of Jenyns' Memoir of Henslow. 1863. Working at "Variation under Domestication." Papers on Yellow Rain, the Pampas, and on Cirripedes. A review of Bates' paper on Mimetic Butterflies. Severe illness to the end of year. 1864. Illness continued until April. Paper on Linum published by the Linnean Society. May 25th: Paper on Lythrum finished. September 13th: Paper on Climbing Plants finished. Work on "Variation under Domestication." November 30th: Copley medal awarded to him. 1865. January 1st: Continued at work on Variation until April 22nd. The work was interrupted by illness until late in the autumn. February: Read paper on Climbing Plants. December 25th: Began again on Variation. 1866. Continued work at "Variation under Domestication." March 1st to May 10th: At work on Edition IV. of the "Origin." Published June (1250 copies). Read paper on Cytisus scoparius to the Linnean Society. December 22nd: Began the last chapter of "Variation under Domestication." 1867. November 15th: Finished revises of "Variation under Domestication." December: Began papers on Illegitimate Unions of Dimorphic and Trimorphic Plants, and on Primula. 1868. January 30th: Publication of "Variation under Domestication." February 4th: Began work on Man. February 10th: New edition of "Variation under Domestication." Read papers on Illegitimate Unions of Dimorphic and Trimorphic Plants, and on Verbascum. 1869. February 10th: "Finished fifth edition of 'Origin'; has taken me forty-six days." Edition V. published in May. Working at the "Descent of Man." Papers on the Fertilisation of Orchids, and on the Fertilisation of Winter-flowering Plants. 1870. Working at the "Descent of Man." Paper on the Pampas Woodpecker. 1871. January 17th: Began the "Expression of the Emotions." February 24th: "Descent of Man" published (2500 copies). April 27th: Finished the rough copy of "Expression." June 18th: Began Edition VI. of "Origin." Paper on the Fertilisation of Leschenaultia. 1872. January 10th: Finished proofs of Edition VI. of the "Origin," and "again rewriting 'Expression.'" August 22nd: Finished last proofs of "Expression." August 23rd: Began working at Drosera. November: "Expression" published (7000 copies, and 2000 more printed at the end of the year.) November 8th: "At Murray's sale 5267 copies sold to London booksellers." 1873. January: Correcting the Climbing Plants paper for publication as a book. February 3rd: At work on "Cross-fertilisation." February to September: Contributions to "Nature." June 14th: "Began Drosera again." November 20th: Began "Descent of Man," Edition II. 1874. "Descent of Man," Edition II, in one volume, published (Preface dated September). "Coral Reefs," Edition II., published. April 1st: Began "Insectivorous Plants." February to May: Contributed notes to "Nature." 1875. July 2nd: "Insectivorous Plants" published (3000 copies); 2700 copies sold immediately. July 6th: "Correcting 2nd edition of 'Variation under Domestication.'" It was published in the autumn. September 1st (approximately): Began on "Cross and Self-Fertilisation." November: Vivisection Commission. 1876. May 5th: "Finished MS., first time over, of 'Cross and Self-Fertilisation.'" May to June: Correction of "Fertilisation of Orchids," Edition II. Wrote his Autobiographical Sketch. May and November: Contributions to "Nature." August 19th: First proofs of "Cross and Self-Fertilisation." November 10th: "Cross and Self-Fertilisation" published (1500 copies). 1877. "All the early part of summer at work on 'Different Forms of Flowers.'" July: Publication of "Different Forms of Flowers" (1250 copies). During the rest of the year at work on the bloom on leaves, movements of plants, "and a little on worms." November: LL.D. at Cambridge. Second edition of "Fertilisation of Orchids" published. Contributions to "Nature," "Gardeners' Chronicle," and "Mind." 1878. The whole year at work on movements of plants, and on the bloom on leaves. May: Contribution to "Nature." Second edition of "Different Forms of Flowers." Wrote prefatory letter to Kerner's "Flowers and their Unbidden Guests." 1879. The whole year at work on movements of plants, except for "about six weeks" in the spring and early summer given to the "Life of Erasmus Darwin," which was published in the autumn. Contributions to "Nature." 1880. "All spring finishing MS. of 'Power of Movement in Plants' and proof sheets." "Began in autumn on Worms." Prefatory notice written for Meldola's translation of Weismann's book. November 6th: 1500 copies of "Power of Movement" sold at Murray's sale. Contributions to "Nature." 1881. During all the early part of the year at work on the "Worm book." Several contributions to "Nature." October 10th: The book on "Earthworms" published: 2000 copies sold at once. November: At work on the action of carbonate of ammonia on plants. 1882. No entries in the Diary. February: At work correcting the sixth thousand of the "Earthworms." March 6th and March 16th: Papers on the action of Carbonate of Ammonia on roots, etc., read at the Linnean Society. April 6th: Note to "Nature" on Dispersal of Bivalves. April 18th: Van Dyck's paper on Syrian Dogs, with a preliminary notice by Charles Darwin, read before the Zoological Society. April 19th: Charles Darwin died at Down. ... CHARLES DARWIN CHAPTER 1.I.--AN AUTOBIOGRAPHICAL FRAGMENT, AND EARLY LETTERS. 1809-1842. (Chapter I./1. In the process of removing the remainder of Mr. Darwin's books and papers from Down, the following autobiographical notes, written in 1838, came to light. They seem to us worth publishing--both as giving some new facts, and also as illustrating the interest which he clearly felt in his own development. Many words are omitted in the manuscript, and some names incorrectly spelled; the corrections which have been made are not always indicated.) My earliest recollection, the date of which I can approximately tell, and which must have been before I was four years old, was when sitting on Caroline's (Caroline Darwin) knee in the drawing room, whilst she was cutting an orange for me, a cow ran by the window which made me jump, so that I received a bad cut, of which I bear the scar to this day. Of this scene I recollect the place where I sat and the cause of the fright, but not the cut itself, and I think my memory is real, and not as often happens in similar cases, [derived] from hearing the thing often repeated, [when] one obtains so vivid an image, that it cannot be separated from memory: because I clearly remember which way the cow ran, which would not probably have been told me. My memory here is an obscure picture, in which from not recollecting any pain I am scarcely conscious of its reference to myself. 1813. When I was four years and a half old I went to the sea, and stayed there some weeks. I remember many things, but with the exception of the maidservants (and these are not individualised) I recollect none of my family who were there. I remember either myself or Catherine being naughty, and being shut up in a room and trying to break the windows. I have an obscure picture of a house before my eyes, and of a neighbouring small shop, where the owner gave me one fig, but which to my great joy turned out to be two: this fig was given me that the man might kiss the maidservant. I remember a common walk to a kind of well, on the road to which was a cottage shaded with damascene (Chapter I./2. Damson is derived from Damascene; the fruit was formerly known as a "Damask Prune.") trees, inhabited by an old man, called a hermit, with white hair, who used to give us damascenes. I know not whether the damascenes, or the reverence and indistinct fear for this old man produced the greatest effect on my memory. I remember when going there crossing in the carriage a broad ford, and fear and astonishment of white foaming water has made a vivid impression. I think memory of events commences abruptly; that is, I remember these earliest things quite as clearly as others very much later in life, which were equally impressed on me. Some very early recollections are connected with fear at Parkfield and with poor Betty Harvey. I remember with horror her story of people being pushed into the canal by the towing rope, by going the wrong side of the horse. I had the greatest horror of this story--keen instinct against death. Some other recollections are those of vanity--namely, thinking that people were admiring me, in one instance for perseverance and another for boldness in climbing a low tree, and what is odder, a consciousness, as if instinctive, that I was vain, and contempt of myself. My supposed admirer was old Peter Haile the bricklayer, and the tree the mountain ash on the lawn. All my recollections seem to be connected most closely with myself; now Catherine (Catherine Darwin) seems to recollect scenes where others were the chief actors. When my mother died I was 8 1/2 years old, and [Catherine] one year less, yet she remembers all particulars and events of each day whilst I scarcely recollect anything (and so with very many other cases) except being sent for, the memory of going into her room, my father meeting me--crying afterwards. I recollect my mother's gown and scarcely anything of her appearance, except one or two walks with her. I have no distinct remembrance of any conversation, and those only of a very trivial nature. I remember her saying "if she did ask me to do something," which I said she had, "it was solely for my good." Catherine remembers my mother crying, when she heard of my grandmother's death. Also when at Parkfield how Aunt Sarah and Aunt Kitty used to receive her. Susan, like me, only remembers affairs personal. It is sufficiently odd this [difference] in subjects remembered. Catherine says she does not remember the impression made upon her by external things, as scenery, but for things which she reads she has an excellent memory, i.e., for ideas. Now her sympathy being ideal, it is part of her character, and shows how easily her kind of memory was stamped, a vivid thought is repeated, a vivid impression forgotten. I remember obscurely the illumination after the battle of Waterloo, and the Militia exercising about that period, in the field opposite our house. 1817. At 8 1/2 years old I went to Mr. Case's School. (Chapter I/3. A day-school at Shrewsbury kept by Rev. G. Case, minister of the Unitarian Chapel ("Life and Letters," Volume I., page 27 et seq.)) I remember how very much I was afraid of meeting the dogs in Barker Street, and how at school I could not get up my courage to fight. I was very timid by nature. I remember I took great delight at school in fishing for newts in the quarry pool. I had thus young formed a strong taste for collecting, chiefly seals, franks, etc., but also pebbles and minerals--one which was given me by some boy decided this taste. I believe shortly after this, or before, I had smattered in botany, and certainly when at Mr. Case's School I was very fond of gardening, and invented some great falsehoods about being able to colour crocuses as I liked. (Chapter I./4. The story is given in the "Life and Letters," I., page 28, the details being slightly different.) At this time I felt very strong friendship for some boys. It was soon after I began collecting stones, i.e., when 9 or 10, that I distinctly recollect the desire I had of being able to know something about every pebble in front of the hall door--it was my earliest and only geological aspiration at that time. I was in those days a very great story-teller--for the pure pleasure of exciting attention and surprise. I stole fruit and hid it for these same motives, and injured trees by barking them for similar ends. I scarcely ever went out walking without saying I had seen a pheasant or some strange bird (natural history taste); these lies, when not detected, I presume, excited my attention, as I recollect them vividly, not connected with shame, though some I do, but as something which by having produced a great effect on my mind, gave pleasure like a tragedy. I recollect when I was at Mr. Case's inventing a whole fabric to show how fond I was of speaking the TRUTH! My invention is still so vivid in my mind, that I could almost fancy it was true, did not memory of former shame tell me it was false. I have no particularly happy or unhappy recollections of this time or earlier periods of my life. I remember well a walk I took with a boy named Ford across some fields to a farmhouse on the Church Stretton road. I do not remember any mental pursuits excepting those of collecting stones, etc., gardening, and about this time often going with my father in his carriage, telling him of my lessons, and seeing game and other wild birds, which was a great delight to me. I was born a naturalist. When I was 9 1/2 years old (July 1818) I went with Erasmus to see Liverpool: it has left no impressions on my mind, except most trifling ones--fear of the coach upsetting, a good dinner, and an extremely vague memory of ships. In Midsummer of this year I went to Dr. Butler's School. (Chapter I./5. Darwin entered Dr. Butler's school in Shrewsbury in the summer of 1818, and remained there till 1825 ("Life and Letters," I., page 30).) I well recollect the first going there, which oddly enough I cannot of going to Mr. Case's, the first school of all. I remember the year 1818 well, not from having first gone to a public school, but from writing those figures in my school book, accompanied with obscure thoughts, now fulfilled, whether I should recollect in future life that year. In September (1818) I was ill with the scarlet fever. I well remember the wretched feeling of being delirious. 1819, July (10 1/2 years old). Went to the sea at Plas Edwards and stayed there three weeks, which now appears to me like three months. (Chapter I./6. Plas Edwards, at Towyn, on the Welsh coast.) I remember a certain shady green road (where I saw a snake) and a waterfall, with a degree of pleasure, which must be connected with the pleasure from scenery, though not directly recognised as such. The sandy plain before the house has left a strong impression, which is obscurely connected with an indistinct remembrance of curious insects, probably a Cimex mottled with red, and Zygaena, the burnet-moth. I was at that time very passionate (when I swore like a trooper) and quarrelsome. The former passion has I think nearly wholly but slowly died away. When journeying there by stage coach I remember a recruiting officer (I think I should know his face to this day) at tea time, asking the maid-servant for toasted bread and butter. I was convulsed with laughter and thought it the quaintest and wittiest speech that ever passed from the mouth of man. Such is wit at 10 1/2 years old. The memory now flashes across me of the pleasure I had in the evening on a blowy day walking along the beach by myself and seeing the gulls and cormorants wending their way home in a wild and irregular course. Such poetic pleasures, felt so keenly in after years, I should not have expected so early in life. 1820, July. Went a riding tour (on old Dobbin) with Erasmus to Pistyll Rhiadr (Chapter I./7. Pistyll Rhiadr proceeds from Llyn Pen Rhiadr down the Llyfnant to the Dovey.); of this I recollect little, an indistinct picture of the fall, but I well remember my astonishment on hearing that fishes could jump up it. (Chapter I./8. The autobiographical fragment here comes to an end. The next letters give some account of Darwin as an Edinburgh student. He has described ("Life and Letters," I., pages 35-45) his failure to be interested in the official teaching of the University, his horror at the operating theatre, and his gradually increasing dislike of medical study, which finally determined his leaving Edinburgh, and entering Cambridge with a view to taking Orders.) LETTER 1. TO R.W. DARWIN. Sunday Morning [Edinburgh, October, 1825]. My dear Father As I suppose Erasmus (Erasmus Darwin) has given all the particulars of the journey, I will say no more about it, except that altogether it has cost me 7 pounds. We got into our lodgings yesterday evening, which are very comfortable and near the College. Our Landlady, by name Mrs. Mackay, is a nice clean old body--exceedingly civil and attentive. She lives in "11, Lothian Street, Edinburgh" (1/1. In a letter printed in the "Edinburgh Evening Despatch" of May 22nd, 1888, the writer suggested that a tablet should be placed on the house, 11, Lothian Street. This suggestion was carried out in 1888 by Mr. Ralph Richardson (Clerk of the Commissary Court, Edinburgh), who obtained permission from the proprietors to affix a tablet to the house, setting forth that Charles Darwin resided there as an Edinburgh University student. We are indebted to Mr. W.K. Dickson for obtaining for us this information, and to Mr. Ralph Richardson for kindly supplying us with particulars. See Mr. Richardson's Inaugural Address, "Trans. Edinb. Geol. Soc." 1894-95; also "Memorable Edinburgh Houses," by Wilmot Harrison, 1898.), and only four flights of steps from the ground-floor, which is very moderate to some other lodgings that we were nearly taking. The terms are 1 pound 6 shillings for two very nice and LIGHT bedrooms and a sitting-room; by the way, light bedrooms are very scarce articles in Edinburgh, since most of them are little holes in which there is neither air nor light. We called on Dr. Hanley the first morning, whom I think we never should have found, had it not been for a good-natured Dr. of Divinity who took us into his library and showed us a map, and gave us directions how to find him. Indeed, all the Scotchmen are so civil and attentive, that it is enough to make an Englishman ashamed of himself. I should think Dr. Butler or any other fat English Divine would take two utter strangers into his library and show them the way! When at last we found the Doctor, and having made all the proper speeches on both sides, we all three set out and walked all about the town, which we admire excessively; indeed Bridge Street is the most extraordinary thing I ever saw, and when we first looked over the sides, we could hardly believe our eyes, when instead of a fine river, we saw a stream of people. We spend all our mornings in promenading about the town, which we know pretty well, and in the evenings we go to the play to hear Miss Stephens (Probably Catherine Stephens), which is quite delightful; she is very popular here, being encored to such a degree, that she can hardly get on with the play. On Monday we are going to Der F (I do not know how to spell the rest of the word). (1/2. "Der F" is doubtless "Der Freischutz," which appeared in 1820, and of which a selection was given in London, under Weber's direction, in 1825. The last of Weber's compositions, "From Chindara's warbling fount," was written for Miss Stephens, who sang it to his accompaniment "the last time his fingers touched the key-board." (See "Dict. of Music," "Stephens" and "Weber.")) Before we got into our lodgings, we were staying at the Star Hotel in Princes St., where to my surprise I met with an old schoolfellow, whom I like very much; he is just come back from a walking tour in Switzerland and is now going to study for his [degree?] The introductory lectures begin next Wednesday, and we were matriculated for them on Saturday; we pay 10s., and write our names in a book, and the ceremony is finished; but the Library is not free to us till we get a ticket from a Professor. We just have been to Church and heard a sermon of only 20 minutes. I expected, from Sir Walter Scott's account, a soul-cutting discourse of 2 hours and a half. I remain your affectionate son, C. DARWIN. LETTER 2. TO CAROLINE DARWIN. January 6th, 1826. Edinburgh. Many thanks for your very entertaining letter, which was a great relief after hearing a long stupid lecture from Duncan on Materia Medica, but as you know nothing either of the Lectures or Lecturers, I will give you a short account of them. Dr. Duncan is so very learned that his wisdom has left no room for his sense, and he lectures, as I have already said, on the Materia Medica, which cannot be translated into any word expressive enough of its stupidity. These few last mornings, however, he has shown signs of improvement, and I hope he will "go on as well as can be expected." His lectures begin at eight in the morning. Dr. Hope begins at ten o'clock, and I like both him and his lectures VERY much (after which Erasmus goes to "Mr. Sizars on Anatomy," who is a charming Lecturer). At 12 the Hospital, after which I attend Monro on Anatomy. I dislike him and his lectures so much, that I cannot speak with decency about them. Thrice a week we have what is called Clinical lectures, which means lectures on the sick people in the Hospital--these I like very much. I said this account should be short, but I am afraid it has been too long, like the lectures themselves. I will be a good boy and tell something about Johnson again (not but what I am very much surprised that Papa should so forget himself as call me, a Collegian in the University of Edinburgh, a boy). He has changed his lodgings for the third time; he has got very cheap ones, but I am afraid it will not answer, for they must make up by cheating. I hope you like Erasmus' official news, he means to begin every letter so. You mentioned in your letter that Emma was staying with you: if she is not gone, ask her to tell Jos that I have not succeeded in getting any titanium, but that I will try again...I want to know how old I shall be next birthday--I believe 17, and if so, I shall be forced to go abroad for one year, since it is necessary that I shall have completed my 21st year before I take my degree. Now you have no business to be frowning and puzzling over this letter, for I did not promise to write a good hand to you. LETTER 3. TO J.S. HENSLOW. (3/1. Extracts from Darwin's letters to Henslow were read before the Cambridge Philosophical Society on November 16th, 1835. Some of the letters were subsequently printed, in an 8vo pamphlet of 31 pages, dated December 1st, 1835, for private distribution among the members of the Society. A German translation by W. Preyer appeared in the "Deutsche Rundschau," June 1891.) [15th August, 1832. Monte Video.] We are now beating up the Rio Plata, and I take the opportunity of beginning a letter to you. I did not send off the specimens from Rio Janeiro, as I grudged the time it would take to pack them up. They are now ready to be sent off and most probably go by this packet. If so they go to Falmouth (where Fitz-Roy has made arrangements) and so will not trouble your brother's agent in London. When I left England I was not fully aware how essential a kindness you offered me when you undertook to receive my boxes. I do not know what I should do without such head-quarters. And now for an apologetical prose about my collection: I am afraid you will say it is very small, but I have not been idle, and you must recollect what a very small show hundreds of species make. The box contains a good many geological specimens; I am well aware that the greater number are too small. But I maintain that no person has a right to accuse me, till he has tried carrying rocks under a tropical sun. I have endeavoured to get specimens of every variety of rock, and have written notes upon all. If you think it worth your while to examine any of them I shall be very glad of some mineralogical information, especially on any numbers between 1 and 254 which include Santiago rocks. By my catalogue I shall know which you may refer to. As for my plants, "pudet pigetque mihi." All I can say is that when objects are present which I can observe and particularise about, I cannot summon resolution to collect when I know nothing. It is positively distressing to walk in the glorious forest amidst such treasures and feel they are all thrown away upon one. My collection from the Abrolhos is interesting, as I suspect it nearly contains the whole flowering vegetation--and indeed from extreme sterility the same may almost be said of Santiago. I have sent home four bottles with animals in spirits, I have three more, but would not send them till I had a fourth. I shall be anxious to hear how they fare. I made an enormous collection of Arachnidae at Rio, also a good many small beetles in pill boxes, but it is not the best time of year for the latter. Amongst the lower animals nothing has so much interested me as finding two species of elegantly coloured true Planaria inhabiting the dewy forest! The false relation they bear to snails is the most extraordinary thing of the kind I have ever seen. In the same genus (or more truly family) some of the marine species possess an organisation so marvellous that I can scarcely credit my eyesight. Every one has heard of the discoloured streaks of water in the equatorial regions. One I examined was owing to the presence of such minute Oscillariae that in each square inch of surface there must have been at least one hundred thousand present. After this I had better be silent, for you will think me a Baron Munchausen amongst naturalists. Most assuredly I might collect a far greater number of specimens of Invertebrate animals if I took less time over each; but I have come to the conclusion that two animals with their original colour and shape noted down will be more valuable to naturalists than six with only dates and place. I hope you will send me your criticisms about my collection; and it will be my endeavour that nothing you say shall be lost on me. I would send home my writings with my specimens, only I find I have so repeatedly occasion to refer back that it would be a serious loss to me. I cannot conclude about my collection without adding that I implicitly trust in your keeping an exact account against all the expense of boxes, etc., etc. At this present minute we are at anchor in the mouth of the river, and such a strange scene as it is. Everything is in flames--the sky with lightning, the water with luminous particles, and even the very masts are pointed with a blue flame. I expect great interest in scouring over the plains of Monte Video, yet I look back with regret to the Tropics, that magic lure to all naturalists. The delight of sitting on a decaying trunk amidst the quiet gloom of the forest is unspeakable and never to be forgotten. How often have I then wished for you. When I see a banana I well recollect admiring them with you in Cambridge--little did I then think how soon I should eat their fruit. August 15th. In a few days the box will go by the "Emulous" packet (Capt. Cooke) to Falmouth and will be forwarded to you. This letter goes the same way, so that if in course of due time you do not receive the box, will you be kind enough to write to Falmouth? We have been here (Monte Video) for some time; but owing to bad weather and continual fighting on shore, we have scarcely ever been able to walk in the country. I have collected during the last month nothing, but to-day I have been out and returned like Noah's Ark with animals of all sorts. I have to-day to my astonishment found two Planariae living under dry stones: ask L. Jenyns if he has ever heard of this fact. I also found a most curious snail, and spiders, beetles, snakes, scorpions ad libitum, and to conclude shot a Cavia weighing a cwt.--On Friday we sail for the Rio Negro, and then will commence our real wild work. I look forward with dread to the wet stormy regions of the south, but after so much pleasure I must put up with some sea-sickness and misery. LETTER 4. TO J.S. HENSLOW. Monte Video, 24th November 1832. We arrived here on the 24th of October, after our first cruise on the coast of Patagonia. North of the Rio Negro we fell in with some little schooners employed in sealing: to save the loss of time in surveying the intricate mass of banks, Capt. Fitz-Roy has hired two of them and has put officers on them. It took us nearly a month fitting them out; as soon as this was finished we came back here, and are now preparing for a long cruise to the south. I expect to find the wild mountainous country of Terra del Fuego very interesting, and after the coast of Patagonia I shall thoroughly enjoy it.--I had hoped for the credit of Dame Nature, no such country as this last existed; in sad reality we coasted along 240 miles of sand hillocks; I never knew before, what a horrid ugly object a sand hillock is. The famed country of the Rio Plata in my opinion is not much better: an enormous brackish river, bounded by an interminable green plain is enough to make any naturalist groan. So Hurrah for Cape Horn and the Land of Storms. Now that I have had my growl out, which is a privilege sailors take on all occasions, I will turn the tables and give an account of my doing in Nat. History. I must have one more growl: by ill luck the French Government has sent one of its collectors to the Rio Negro, where he has been working for the last six months, and is now gone round the Horn. So that I am very selfishly afraid he will get the cream of all the good things before me. As I have nobody to talk to about my luck and ill luck in collecting, I am determined to vent it all upon you. I have been very lucky with fossil bones; I have fragments of at least 6 distinct animals: as many of them are teeth, I trust, shattered and rolled as they have been, they will be recognised. I have paid all the attention I am capable of to their geological site; but of course it is too long a story for here. 1st, I have the tarsi and metatarsi very perfect of a Cavia; 2nd, the upper jaw and head of some very large animal with four square hollow molars and the head greatly protruded in front. I at first thought it belonged either to the Megalonyx or Megatherium (4/1). The animal may probably have been Grypotherium Darwini, Ow. The osseous plates mentioned below must have belonged to one of the Glyptodontidae, and not to Megatherium. We are indebted to Mr. Kerr for calling our attention to a passage in Buckland's "Bridgewater Treatise" (Volume II., page 20, note), where bony armour is ascribed to Megatherium.); in confirmation of this in the same formation I found a large surface of the osseous polygonal plates, which "late observations" (what are they?) show belong to the Megatherium. Immediately I saw this I thought they must belong to an enormous armadillo, living species of which genus are so abundant here. 3rd, The lower jaw of some large animal which, from the molar teeth, I should think belonged to the Edentata; 4th, some large molar teeth which in some respects would seem to belong to an enormous rodent; 5th, also some smaller teeth belonging to the same order. If it interests you sufficiently to unpack them, I shall be very curious to hear something about them. Care must be taken in this case not to confuse the tallies. They are mingled with marine shells which appear to me identical with what now exist. But since they were deposited in their beds several geological changes have taken place in the country. So much for the dead, and now for the living: there is a poor specimen of a bird which to my unornithological eyes appears to be a happy mixture of a lark, pigeon and snipe (No. 710). Mr. MacLeay himself never imagined such an inosculating creature: I suppose it will turn out to be some well-known bird, although it has quite baffled me. I have taken some interesting Amphibia; a new Trigonocephalus beautifully connecting in its habits Crotalus and the Viperidae, and plenty of new (as far as my knowledge goes) saurians. As for one little toad, I hope it may be new, that it may be christened "diabolicus." Milton must allude to this very individual when he talks of "squat like a toad" (4/2. "...him [Satan] there they [Ithuriel and Zephon] found, Squat like a toad, close at the ear of Eve" ("Paradise Lost," Book IV., line 800). "Formerly Milton's "Paradise Lost" had been my chief favourite, and in my excursions during the voyage of the 'Beagle,' when I could take only a single volume, I always chose Milton" ("Autobiography," page 69).); its colours are by Werner (4/3. Werner's "Nomenclature of Colours," Edinburgh, 1821.) ink black, vermilion red and buff orange. It has been a splendid cruise for me in Nat. History. Amongst the Pelagic Crustacea, some new and curious genera. In the Zoophytes some interesting animals. As for one Flustra, if I had not the specimen to back me up nobody would believe in its most anomalous structure. But as for novelty all this is nothing to a family of pelagic animals which at first sight appear like Medusae but are really highly organised. I have examined them repeatedly, and certainly from their structure it would be impossible to place them in any existing order. Perhaps Salpa is the nearest animal, although the transparency of the body is nearly the only character they have in common. I think the dried plants nearly contain all which were then (Bahia Blanca) flowering. All the specimens will be packed in casks. I think there will be three (before sending this letter I will specify dates, etc., etc.). I am afraid you will groan or rather the floor of the lecture room will when the casks arrive. Without you I should be utterly undone. The small cask contains fish: will you open it to see how the spirit has stood the evaporation of the Tropics. On board the ship everything goes on as well as possible; the only drawback is the fearful length of time between this and the day of our return. I do not see any limits to it. One year is nearly completed and the second will be so, before we even leave the east coast of S. America. And then our voyage may be said really to have commenced. I know not how I shall be able to endure it. The frequency with which I think of all the happy hours I have spent at Shrewsbury and Cambridge is rather ominous--I trust everything to time and fate and will feel my way as I go on. November 24th.--We have been at Buenos Ayres for a week; it is a fine large city, but such a country, everything is mud, you can go nowhere, you can do nothing for mud. In the city I obtained much information about the banks of the Uruguay--I hear of limestone with shells, and beds of shells in every direction. I hope when we winter in the Plata to have a most interesting geological excursion into that country: I purchased fragments (Nos. 837-8) of some enormous bones, which I was assured belonged to the former giants!! I also procured some seeds--I do not know whether they are worth your accepting; if you think so I will get some more. They are in the box. I have sent to you by the "Duke of York" packet, commanded by Lieut. Snell, to Falmouth two large casks containing fossil bones, a small cask with fish and a box containing skins, spirit bottle, etc., and pill-boxes with beetles. Would you be kind enough to open these latter as they are apt to become mouldy. With the exception of the bones the rest of my collection looks very scanty. Recollect how great a proportion of time is spent at sea. I am always anxious to hear in what state the things come and any criticisms about quantity or kind of specimens. In the smaller cask is part of a large head, the anterior portions of which are in the other large one. The packet has arrived and I am in a great bustle. You will not hear from me for some months. LETTER 5. TO J.S. HENSLOW. Valparaiso, July 24th 1834. A box has just arrived in which were two of your most kind and affectionate letters. You do not know how happy they have made me. One is dated December 15th, 1833, the other January 15th of the same year! By what fatality it did not arrive sooner I cannot conjecture; I regret it much, for it contains the information I most wanted, about manner of packing, etc., etc.: roots with specimens of plants, etc., etc. This I suppose was written after the reception of my first cargo of specimens. Not having heard from you until March of this year I really began to think that my collections were so poor, that you were puzzled what to say; the case is now quite on the opposite tack; for you are guilty of exciting all my vain feelings to a most comfortable pitch; if hard work will atone for these thoughts, I vow it shall not be spared. It is rather late, but I will allude to some remarks in the January letter; you advise me to send home duplicates of my notes; I have been aware of the advantage of doing so; but then at sea to this day, I am invariably sick, excepting on the finest days, at which times with pelagic animals around me, I could never bring myself to the task--on shore the most prudent person could hardly expect such a sacrifice of time. My notes are becoming bulky. I have about 600 small quarto pages full; about half of this is Geology--the other imperfect descriptions of animals; with the latter I make it a rule only to describe those parts or facts, which cannot be seen in specimens in spirits. I keep my private Journal distinct from the above. (N.B. this letter is a most untidy one, but my mind is untidy with joy; it is your fault, so you must take the consequences.) With respect to the land Planariae, unquestionably they are not molluscous animals. I read your letters last night, this morning I took a little walk; by a curious coincidence, I found a new white species of Planaria, and a new to me Vaginulus (third species which I have found in S. America) of Cuvier. Amongst the marine mollusques I have seen a good many genera, and at Rio found one quite new one. With respect to the December letter, I am very glad to hear the four casks arrived safe; since which time you have received another cargo, with the bird skins about which you did not understand me. Have any of the B. Ayrean seeds produced plants? From the Falklands I acknowledged a box and letter from you; with the letter were a few seeds from Patagonia. At present I have specimens enough to make a heavy cargo, but shall wait as much longer as possible, because opportunities are not now so good as before. I have just got scent of some fossil bones of a MAMMOTH; what they may be I do not know, but if gold or galloping will get them they shall be mine. You tell me you like hearing how I am going on and what doing, and you well may imagine how much I enjoy speaking to any one upon subjects which I am always thinking about, but never have any one to talk to [about]. After leaving the Falklands we proceeded to the Rio S. Cruz, following up the river till within twenty miles of the Cordilleras. Unfortunately want of provisions compelled us to return. This expedition was most important to me as it was a transverse section of the great Patagonian formation. I conjecture (an accurate examination of fossils may possibly determine the point) that the main bed is somewhere about the Miocene period (using Mr. Lyell's expression); I judge from what I have seen of the present shells of Patagonia. This bed contains an ENORMOUS field of lava. This is of some interest, as being a rude approximation to the age of the volcanic part of the great range of the Andes. Long before this it existed as a slate and porphyritic line of hills. I have collected a tolerable quantity of information respecting the period and forms of elevations of these plains. I think these will be interesting to Mr. Lyell; I had deferred reading his third volume till my return: you may guess how much pleasure it gave me; some of his woodcuts came so exactly into play that I have only to refer to them instead of redrawing similar ones. I had my barometer with me, I only wish I had used it more in these plains. The valley of S. Cruz appears to me a very curious one; at first it quite baffled me. I believe I can show good reasons for supposing it to have been once a northern straits like to that of Magellan. When I return to England you will have some hard work in winnowing my Geology; what little I know I have learnt in such a curious fashion that I often feel very doubtful about the number of grains [of value?]. Whatever number they may turn out, I have enjoyed extreme pleasure in collecting them. In T. del Fuego I collected and examined some corallines; I have observed one fact which quite startled me: it is that in the genus Sertularia (taken in its most restricted form as [used] by Lamoureux) and in two species which, excluding comparative expressions, I should find much difficulty in describing as different, the polypi quite and essentially differed in all their most important and evident parts of structure. I have already seen enough to be convinced that the present families of corallines as arranged by Lamarck, Cuvier, etc., are highly artificial. It appears that they are in the same state [in] which shells were when Linnaeus left them for Cuvier to rearrange. I do so wish I was a better hand at dissecting, I find I can do very little in the minute parts of structure; I am forced to take a very rough examination as a type for different classes of structure. It is most extraordinary I can nowhere see in my books one single description of the polypus of any one coralline excepting Alcyonium Lobularia of Savigny. I found a curious little stony Cellaria (5/1. Cellaria, a genus of Bryozoa, placed in the section Flustrina of the Suborder Chilostomata.) (a new genus) each cell provided with long toothed bristle, these are capable of various and rapid motions. This motion is often simultaneous, and can be produced by irritation. This fact, as far as I can see, is quite isolated in the history of zoophytes (excepting the Flustra with an organ like a vulture's head); it points out a much more intimate relation between the polypi than Lamarck is willing to allow. I forgot whether I mentioned having seen something of the manner of propagation in that most ambiguous family, the corallines; I feel pretty well convinced if they are not plants they are not zoophytes. The "gemmule" of a Halimeda contained several articulations united, ready to burst their envelope, and become attached to some basis. I believe in zoophytes universally the gemmule produces a single polypus, which afterwards or at the same time grows with its cell or single articulation. The "Beagle" left the Sts. of Magellan in the middle of winter; she found her road out by a wild unfrequented channel; well might Sir J. Narborough call the west coast South Desolation, "because it is so desolate a land to behold." We were driven into Chiloe by some very bad weather. An Englishman gave me three specimens of that very fine Lucanoidal insect which is described in the "Camb. Phil. Trans." (5/2. "Description of Chiasognathus Grantii, a new Lucanideous Insect, etc." by J.F. Stephens ("Trans. Camb. Phil. Soc." Volume IV., page 209, 1833.)), two males and one female. I find Chiloe is composed of lava and recent deposits. The lavas are curious from abounding in, or rather being in parts composed of pitchstone. If we go to Chiloe in the summer, I shall reap an entomological harvest. I suppose the Botany both there and in Chili is well-known. I forgot to state that in the four cargoes of specimens there have been sent three square boxes, each containing four glass bottles. I mention this in case they should be stowed beneath geological specimens and thus escape your notice, perhaps some spirit may be wanted in them. If a box arrives from B. Ayres with a Megatherium head the other unnumbered specimens, be kind enough to tell me, as I have strong fears for its safety. We arrived here the day before yesterday; the views of the distant mountains are most sublime and the climate delightful; after our long cruise in the damp gloomy climates of the south, to breathe a clear dry air and feel honest warm sunshine, and eat good fresh roast beef must be the summum bonum of human life. I do not like the look of the rocks half so much as the beef, there is too much of those rather insipid ingredients, mica, quartz and feldspar. Our plans are at present undecided; there is a good deal of work to the south of Valparaiso and to the north an indefinite quantity. I look forward to every part with interest. I have sent you in this letter a sad dose of egotism, but recollect I look up to you as my father in Natural History, and a son may talk about himself to his father. In your paternal capacity as proproctor what a great deal of trouble you appear to have had. How turbulent Cambridge is become. Before this time it will have regained its tranquillity. I have a most schoolboy-like wish to be there, enjoying my holidays. It is a most comfortable reflection to me, that a ship being made of wood and iron, cannot last for ever, and therefore this voyage must have an end. October 28th. This letter has been lying in my portfolio ever since July; I did not send it away because I did not think it worth the postage; it shall now go with a box of specimens. Shortly after arriving here I set out on a geological excursion, and had a very pleasant ramble about the base of the Andes. The whole country appears composed of breccias (and I imagine slates) which universally have been modified and oftentimes completely altered by the action of fire. The varieties of porphyry thus produced are endless, but nowhere have I yet met with rocks which have flowed in a stream; dykes of greenstone are very numerous. Modern volcanic action is entirely shut up in the very central parts (which cannot now be reached on account of the snow) of the Cordilleras. In the south of the R. Maypu I examined the Tertiary plains, already partially described by M. Gay. (5/3. "Rapport fait a l'Academie Royale des Sciences, sur les Travaux Geologiques de M. Gay," by Alex. Brongniart ("Ann. Sci. Nat." Volume XXVIII., page 394, 1833.) The fossil shells appear to me to be far more different from the recent ones than in the great Patagonian formation; it will be curious if an Eocene and Miocene (recent there is abundance of) could be proved to exist in S. America as well as in Europe. I have been much interested by finding abundance of recent shells at an elevation of 1,300 feet; the country in many places is scattered over with shells but these are all littoral ones. So that I suppose the 1,300 feet elevation must be owing to a succession of small elevations such as in 1822. With these certain proofs of the recent residence of the ocean over all the lower parts of Chili, the outline of every view and the form of each valley possesses a high interest. Has the action of running water or the sea formed this deep ravine? was a question which often arose in my mind and generally was answered by finding a bed of recent shells at the bottom. I have not sufficient arguments, but I do not believe that more than a small fraction of the height of the Andes has been formed within the Tertiary period. The conclusion of my excursion was very unfortunate, I became unwell and could hardly reach this place. I have been in bed for the last month, but am now rapidly getting well. I had hoped during this time to have made a good collection of insects but it has been impossible: I regret the less because Chiloe fairly swarms with collectors; there are more naturalists in the country, than carpenters or shoemakers or any other honest trade. In my letter from the Falkland Islands I said I had fears about a box with a Megatherium. I have since heard from B. Ayres that it went to Liverpool by the brig "Basingwaithe." If you have not received it, it is I think worth taking some trouble about. In October two casks and a jar were sent by H.M.S. "Samarang" via Portsmouth. I have no doubt you have received them. With this letter I send a good many bird skins; in the same box with them, there is a paper parcel containing pill boxes with insects. The other pill boxes require no particular care. You will see in two of these boxes some dried Planariae (terrestrial), the only method I have found of preserving them (they are exceedingly brittle). By examining the white species I understand some little of the internal structure. There are two small parcels of seeds. There are some plants which I hope may interest you, or at least those from Patagonia where I collected every one in flower. There is a bottle clumsily but I think securely corked containing water and gas from the hot baths of Cauquenes seated at foot of Andes and long celebrated for medicinal properties. I took pains in filling and securing both water and gas. If you can find any one who likes to analyze them, I should think it would be worth the trouble. I have not time at present to copy my few observations about the locality, etc., etc., [of] these springs. Will you tell me how the Arachnidae which I have sent home, for instance those from Rio, appear to be preserved. I have doubts whether it is worth while collecting them. We sail the day after to-morrow: our plans are at last limited and definite; I am delighted to say we have bid an eternal adieu to T. del Fuego. The "Beagle" will not proceed further south than C. Tres Montes; from which point we survey to the north. The Chonos Archipelago is delightfully unknown: fine deep inlets running into the Cordilleras--where we can steer by the light of a volcano. I do not know which part of the voyage now offers the most attractions. This is a shamefully untidy letter, but you must forgive me. LETTER 6. TO J.S. HENSLOW. April 18th, 1835. Valparaiso. I have just returned from Mendoza, having crossed the Cordilleras by two passes. This trip has added much to my knowledge of the geology of the country. Some of the facts, of the truth of which I in my own mind feel fully convinced, will appear to you quite absurd and incredible. I will give a very short sketch of the structure of these huge mountains. In the Portillo pass (the more southern one) travellers have described the Cordilleras to consist of a double chain of nearly equal altitude separated by a considerable interval. This is the case; and the same structure extends to the northward to Uspallata; the little elevation of the eastern line (here not more than 6,000-7,000 feet.) has caused it almost to be overlooked. To begin with the western and principal chain, we have, where the sections are best seen, an enormous mass of a porphyritic conglomerate resting on granite. This latter rock seems to form the nucleus of the whole mass, and is seen in the deep lateral valleys, injected amongst, upheaving, overturning in the most extraordinary manner, the overlying strata. The stratification in all the mountains is beautifully distinct and from a variety in the colour can be seen at great distances. I cannot imagine any part of the world presenting a more extraordinary scene of the breaking up of the crust of the globe than the very central parts of the Andes. The upheaval has taken place by a great number of (nearly) N. and S. lines; which in most cases have formed as many anticlinal and synclinal ravines; the strata in the highest pinnacles are almost universally inclined at an angle from 70 deg to 80 deg. I cannot tell you how I enjoyed some of these views--it is worth coming from England, once to feel such intense delight; at an elevation from 10 to 12,000 feet there is a transparency in the air, and a confusion of distances and a sort of stillness which gives the sensation of being in another world, and when to this is joined the picture so plainly drawn of the great epochs of violence, it causes in the mind a most strange assemblage of ideas. The formation I call Porphyritic Conglomerates is the most important and most developed one in Chili: from a great number of sections I find it a true coarse conglomerate or breccia, which by every step in a slow gradation passes into a fine claystone-porphyry; the pebbles and cement becoming porphyritic till at last all is blended in one compact rock. The porphyries are excessively abundant in this chain. I feel sure at least 4/5ths of them have been thus produced from sedimentary beds in situ. There are porphyries which have been injected from below amongst strata, and others ejected, which have flowed in streams; it is remarkable, and I could show specimens of this rock produced in these three methods, which cannot be distinguished. It is a great mistake considering the Cordilleras here as composed of rocks which have flowed in streams. In this range I nowhere saw a fragment, which I believe to have thus originated, although the road passes at no great distance from the active volcanoes. The porphyries, conglomerate, sandstone and quartzose sandstone and limestones alternate and pass into each other many times, overlying (where not broken through by the granite) clay-slate. In the upper parts, the sandstone begins to alternate with gypsum, till at last we have this substance of a stupendous thickness. I really think the formation is in some places (it varies much) nearly 2,000 feet thick, it occurs often with a green (epidote?) siliceous sandstone and snow-white marble; it resembles that found in the Alps in containing large concretions of a crystalline marble of a blackish grey colour. The upper beds which form some of the higher pinnacles consist of layers of snow-white gypsum and red compact sandstone, from the thickness of paper to a few feet, alternating in an endless round. The rock has a most curiously painted appearance. At the pass of the Peuquenes in this formation, where however a black rock like clay-slate, without many laminae, occurring with a pale limestone, has replaced the red sandstone, I found abundant impressions of shells. The elevation must be between 12 and 13,000 feet. A shell which I believe is the Gryphaea is the most abundant--an Ostrea, Turratella, Ammonites, small bivalves, Terebratulae (?). Perhaps some good conchologist (6/1. Some of these genera are mentioned by Darwin ("Geol. Obs." page 181) as having been named for him by M. D'Orbigny.) will be able to give a guess, to what grand division of the formations of Europe these organic remains bear most resemblance. They are exceedingly imperfect and few. It was late in the season and the situation particularly dangerous for snow-storms. I did not dare to delay, otherwise a grand harvest might have been reaped. So much for the western line; in the Portillo pass, proceeding eastward, we meet an immense mass of conglomerate, dipping to the west 45 deg, which rest on micaceous sandstone, etc., etc., upheaved and converted into quartz-rock penetrated by dykes from the very grand mass of protogine (large crystals of quartz, red feldspar, and occasional little chlorite). Now this conglomerate which reposes on and dips from the protogene 45 deg consists of the peculiar rocks of the first described chain, pebbles of the black rock with shells, green sandstone, etc., etc. It is hence manifest that the upheaval (and deposition at least of part) of the grand eastern chain is entirely posterior to the western. To the north in the Uspallata pass, we have also a fact of the same class. Bear this in mind: it will help to make you believe what follows. I have said the Uspallata range is geologically, although only 6,000-7,000 feet, a continuation of the grand eastern chain. It has its nucleus of granite, consists of grand beds of various crystalline rocks, which I can feel no doubt are subaqueous lavas alternating with sandstone, conglomerates and white aluminous beds (like decomposed feldspar) with many other curious varieties of sedimentary deposits. These lavas and sandstones alterate very many times, and are quite conformable one to the other. During two days of careful examination I said to myself at least fifty times, how exactly like (only rather harder) these beds are to those of the upper Tertiary strata of Patagonia, Chiloe and Concepcion, without the possible identity ever having occurred to me. At last there was no resisting the conclusion. I could not expect shells, for they never occur in this formation; but lignite or carbonaceous shale ought to be found. I had previously been exceedingly puzzled by meeting in the sandstone, thin layers (few inches to feet thick) of a brecciated pitchstone. I strongly suspect the underlying granite has altered such beds into this pitchstone. The silicified wood (particularly characteristic) was yet absent. The conviction that I was on the Tertiary strata was so strong by this time in my mind, that on the third day in the midst of lavas and [? masses] of granite I began my apparently forlorn hunt. How do you think I succeeded? In an escarpement of compact greenish sandstone, I found a small wood of petrified trees in a vertical position, or rather the strata were inclined about 20-30 deg to one point and the trees 70 deg to the opposite one. That is, they were before the tilt truly vertical. The sandstone consists of many layers, and is marked by the concentric lines of the bark (I have specimens); 11 are perfectly silicified and resemble the dicotyledonous wood which I have found at Chiloe and Concepcion (6/2. "Geol. Obs." page 202. Specimens of the silicified wood were examined by Robert Brown, and determined by him as coniferous, "partaking of the characters of the Araucarian tribe, with some curious points of affinity with the yew."); the others (30-40) I only know to be trees from the analogy of form and position; they consist of snow-white columns (like Lot's wife) of coarsely crystalline carb. of lime. The largest shaft is 7 feet. They are all close together, within 100 yards, and about the same level: nowhere else could I find any. It cannot be doubted that the layers of fine sandstone have quietly been deposited between a clump of trees which were fixed by their roots. The sandstone rests on lava, is covered by a great bed apparently about 1,000 feet thick of black augitic lava, and over this there are at least 5 grand alternations of such rocks and aqueous sedimentary deposits, amounting in thickness to several thousand feet. I am quite afraid of the only conclusion which I can draw from this fact, namely that there must have been a depression in the surface of the land to that amount. But neglecting this consideration, it was a most satisfactory support of my presumption of the Tertiary (I mean by Tertiary, that the shells of the period were closely allied, or some identical, to those which now live, as in the lower beds of Patagonia) age of this eastern chain. A great part of the proof must remain upon my ipse dixit of a mineralogical resemblance with those beds whose age is known, and the character of which resemblance is to be subject to infinite variation, passing from one variety to another by a concretionary structure. I hardly expect you to believe me, when it is a consequence of this view that granite, which forms peaks of a height probably of 14,000 feet, has been fluid in the Tertiary period; that strata of that period are altered by its heat, and are traversed by dykes from the mass. That these strata have also probably undergone an immense depression, that they are now inclined at high angles and form regular or complicated anticlinal lines. To complete the climax and seal your disbelief, these same sedimentary strata and lavas are traversed by VERY NUMEROUS, true metallic veins of iron, copper, arsenic, silver and gold, and these can be traced to the underlying granite. A gold mine has been worked close to the clump of silicified trees. If when you see my specimens, sections and account, you should think that there is pretty strong presumptive evidence of the above facts, it appears very important; for the structure, and size of this chain will bear comparison with any in the world, and that this all should have been produced in so very recent a period is indeed wonderful. In my own mind I am quite convinced of the reality of this. I can anyhow most conscientiously say that no previously formed conjecture warped my judgment. As I have described so did I actually observe the facts. But I will have some mercy and end this most lengthy account of my geological trip. On some of the large patches of perpetual snow, I found the famous red snow of the Arctic countries; I send with this letter my observations and a piece of paper on which I tried to dry some specimens. If the fact is new and you think it worth while, either yourself examine them or send them to whoever has described the specimens from the north and publish a notice in any of the periodicals. I also send a small bottle with two lizards, one of them is viviparous as you will see by the accompanying notice. A M. Gay--a French naturalist--has already published in one of the newspapers of this country a similar statement and probably has forwarded to Paris some account; as the fact appears singular would it not be worth while to hand over the specimens to some good lizardologist and comparative anatomist to publish an account of their internal structure? Do what you think fit. This letter will go with a cargo of specimens from Coquimbo. I shall write to let you know when they are sent off. In the box there are two bags of seeds, one [from the] valleys of the Cordilleras 5,000-10,000 feet high, the soil and climate exceedingly dry, soil very light and stony, extremes in temperature; the other chiefly from the dry sandy Traversia of Mendoza 3,000 feet more or less. If some of the bushes should grow but not be healthy, try a slight sprinkling of salt and saltpetre. The plain is saliferous. All the flowers in the Cordilleras appear to be autumnal flowerers--they were all in blow and seed, many of them very pretty. I gathered them as I rode along on the hill sides. If they will but choose to come up, I have no doubt many would be great rarities. In the Mendoza bag there are the seeds or berries of what appears to be a small potato plant with a whitish flower. They grow many leagues from where any habitation could ever have existed owing to absence of water. Amongst the Chonos dried plants, you will see a fine specimen of the wild potato, growing under a most opposite climate, and unquestionably a true wild potato. It must be a distinct species from that of the Lower Cordilleras one. Perhaps as with the banana, distinct species are now not to be distinguished in their varieties produced by cultivation. I cannot copy out the few remarks about the Chonos potato. With the specimens there is a bundle of old papers and notebooks. Will you take care of them; in case I should lose my notes, these might be useful. I do not send home any insects because they must be troublesome to you, and now so little more of the voyage remains unfinished I can well take charge of them. In two or three days I set out for Coquimbo by land; the "Beagle" calls for me in the beginning of June. So that I have six weeks more to enjoy geologising over these curious mountains of Chili. There is at present a bloody revolution in Peru. The Commodore has gone there, and in the hurry has carried our letters with him; perhaps amongst them there will be one from you. I wish I had the old Commodore here, I would shake some consideration for others into his old body. From Coquimbo you will again hear from me. LETTER 7. TO J.S. HENSLOW. Lima, July 12th, 1835. This is the last letter which I shall ever write to you from the shores of America, and for this reason I send it. In a few days time the "Beagle" will sail for the Galapagos Islands. I look forward with joy and interest to this, both as being somewhat nearer to England and for the sake of having a good look at an active volcano. Although we have seen lava in abundance, I have never yet beheld the crater. I sent by H.M.S. "Conway" two large boxes of specimens. The "Conway" sailed the latter end of June. With them were letters for you, since that time I have travelled by land from Valparaiso to Copiapo and seen something more of the Cordilleras. Some of my geological views have been, subsequently to the last letter, altered. I believe the upper mass of strata is not so very modern as I supposed. This last journey has explained to me much of the ancient history of the Cordilleras. I feel sure they formerly consisted of a chain of volcanoes from which enormous streams of lava were poured forth at the bottom of the sea. These alternate with sedimentary beds to a vast thickness; at a subsequent period these volcanoes must have formed islands, from which have been produced strata of several thousand feet thick of coarse conglomerate. (7/1. See "Geological Observations on South America" (London, 1846), Chapter VII.: "Central Chile; Structure of the Cordillera.") These islands were covered with fine trees; in the conglomerate, I found one 15 feet in circumference perfectly silicified to the very centre. The alternations of compact crystalline rocks (I cannot doubt subaqueous lavas), and sedimentary beds, now upheaved fractured and indurated, form the main range of the Andes. The formation was produced at the time when ammonites, gryphites, oysters, Pecten, Mytilus, etc., etc., lived. In the central parts of Chili the structure of the lower beds is rendered very obscure by the metamorphic action which has rendered even the coarsest conglomerates porphyritic. The Cordilleras of the Andes so worthy of admiration from the grandeur of their dimensions, rise in dignity when it is considered that since the period of ammonites, they have formed a marked feature in the geography of the globe. The geology of these mountains pleased me in one respect; when reading Lyell, it had always struck me that if the crust of the world goes on changing in a circle, there ought to be somewhere found formations which, having the age of the great European Secondary beds, should possess the structure of Tertiary rocks or those formed amidst islands and in limited basins. Now the alternations of lava and coarse sediment which form the upper parts of the Andes, correspond exactly to what would accumulate under such circumstances. In consequence of this, I can only very roughly separate into three divisions the varying strata (perhaps 8,000 feet thick) which compose these mountains. I am afraid you will tell me to learn my ABC to know quartz from feldspar before I indulge in such speculations. I lately got hold of a report on M. Dessalines D'Orbigny's labours in S. America (7/2. "Voyage dans l'Amerique Meridionale, etc." (A. Dessalines D'Orbigny).); I experienced rather a debasing degree of vexation to find he has described the Geology of the Pampas, and that I have had some hard riding for nothing, it was however gratifying that my conclusions are the same, as far as I can collect, with his results. It is also capital that the whole of Bolivia will be described. I hope to be able to connect his geology of that country with mine of Chili. After leaving Copiapo, we touched at Iquique. I visited but do not quite understand the position of the nitrate of soda beds. Here in Peru, from the state of anarchy, I can make no expedition. I hear from home, that my brother is going to send me a box with books, and a letter from you. It is very unfortunate that I cannot receive this before we reach Sydney, even if it ever gets safely so far. I shall not have another opportunity for many months of again writing to you. Will you have the charity to send me one more letter (as soon as this reaches you) directed to the C. of Good Hope. Your letters besides affording me the greatest delight always give me a fresh stimulus for exertion. Excuse this geological prosy letter, and farewell till you hear from me at Sydney, and see me in the autumn of 1836. LETTER 8. TO JOSIAH WEDGWOOD. [Shrewsbury, October 5th, 1836.] My dear Uncle The "Beagle" arrived at Falmouth on Sunday evening, and I reached home late last night. My head is quite confused with so much delight, but I cannot allow my sisters to tell you first how happy I am to see all my dear friends again. I am obliged to return in three or four days to London, where the "Beagle" will be paid off, and then I shall pay Shrewsbury a longer visit. I am most anxious once again to see Maer, and all its inhabitants, so that in the course of two or three weeks, I hope in person to thank you, as being my first Lord of the Admiralty. (8/1.) Readers of the "Life and Letters" will remember that it was to Josiah Wedgwood that Darwin owed the great opportunity of his life ("Life and Letters," Volume I., page 59), and it was fitting that he should report himself to his "first Lord of the Admiralty." The present letter clears up a small obscurity to which Mr. Poulton has called attention ("Charles Darwin and the Theory of Natural Selection," "Century" Series, 1896, page 25). Writing to Fitz-Roy from Shrewsbury on October 6th, Darwin says, "I arrived here yesterday morning at breakfast time." This refers to his arrival at his father's house, after having slept at the inn. The date of his arrival in Shrewsbury was, therefore, October 4th, as given in the "Life and Letters," I., page 272.) The entries in his Diary are:--October 2, 1831. Took leave of my home. October 4, 1836. Reached Shrewsbury after absence of 5 years and 2 days.) I am so very happy I hardly know what I am writing. Believe me your most affectionate nephew, CHAS. DARWIN. LETTER 9. TO C. LYELL. Shrewsbury, Monday [November 12th, 1838]. My dear Lyell I suppose you will be in Hart St. (9/1. Sir Charles Lyell lived at 16, Hart Street, Bloomsbury.) to-morrow [or] the 14th. I write because I cannot avoid wishing to be the first person to tell Mrs. Lyell and yourself, that I have the very good, and shortly since [i.e. until lately] very unexpected fortune of going to be married! The lady is my cousin Miss Emma Wedgwood, the sister of Hensleigh Wedgwood, and of the elder brother who married my sister, so we are connected by manifold ties, besides on my part, by the most sincere love and hearty gratitude to her for accepting such a one as myself. I determined when last at Maer to try my chance, but I hardly expected such good fortune would turn up for me. I shall be in town in the middle or latter end of the ensuing week. (9/2. Mr. Darwin was married on January 29th, 1839 (see "Life and Letters," I., page 299). The present letter was written the day after he had become engaged.) I fear you will say I might very well have left my story untold till we met. But I deeply feel your kindness and friendship towards me, which in truth I may say, has been one chief source of happiness to me, ever since my return to England: so you must excuse me. I am well sure that Mrs. Lyell, who has sympathy for every one near her, will give me her hearty congratulations. Believe me my dear Lyell Yours most truly obliged CHAS. DARWIN. (PLATE: MRS. DARWIN. Walker and Cockerell, ph. sc.) LETTER 10. TO EMMA WEDGWOOD. Sunday Night. Athenaeum. [January 20th, 1839.] ...I cannot tell you how much I enjoyed my Maer visit,--I felt in anticipation my future tranquil life: how I do hope you may be as happy as I know I shall be: but it frightens me, as often as I think of what a family you have been one of. I was thinking this morning how it came, that I, who am fond of talking and am scarcely ever out of spirits, should so entirely rest my notions of happiness on quietness, and a good deal of solitude: but I believe the explanation is very simple and I mention it because it will give you hopes, that I shall gradually grow less of a brute, it is that during the five years of my voyage (and indeed I may add these two last) which from the active manner in which they have been passed, may be said to be the commencement of my real life, the whole of my pleasure was derived from what passed in my mind, while admiring views by myself, travelling across the wild deserts or glorious forests or pacing the deck of the poor little "Beagle" at night. Excuse this much egotism,--I give it you because I think you will humanize me, and soon teach me there is greater happiness than building theories and accumulating facts in silence and solitude. My own dearest Emma, I earnestly pray, you may never regret the great, and I will add very good, deed, you are to perform on the Tuesday: my own dear future wife, God bless you...The Lyells called on me to-day after church; as Lyell was so full of geology he was obliged to disgorge,--and I dine there on Tuesday for an especial confidence. I was quite ashamed of myself to-day, for we talked for half an hour, unsophisticated geology, with poor Mrs. Lyell sitting by, a monument of patience. I want practice in ill-treatment the female sex,--I did not observe Lyell had any compunction; I hope to harden my conscience in time: few husbands seem to find it difficult to effect this. Since my return I have taken several looks, as you will readily believe, into the drawing-room; I suppose my taste [for] harmonious colours is already deteriorated, for I declare the room begins to look less ugly. I take so much pleasure in the house (10/1. No. 12, Upper Gower Street, is now No. 110, Gower Street, and forms part of a block inhabited by Messrs. Shoolbred's employes. We are indebted, for this information, to Mr. Wheatley, of the Society of Arts.), I declare I am just like a great overgrown child with a new toy; but then, not like a real child, I long to have a co-partner and possessor. (10/2. The following passage is taken from the MS. copy of the "Autobiography;" it was not published in the "Life and Letters" which appeared in Mrs. Darwin's lifetime:--) You all know your mother, and what a good mother she has ever been to all of you. She has been my greatest blessing, and I can declare that in my whole life I have never heard her utter one word I would rather have been unsaid. She has never failed in kindest sympathy towards me, and has borne with the utmost patience my frequent complaints of ill-health and discomfort. I do not believe she has ever missed an opportunity of doing a kind action to any one near her. I marvel at my good fortune that she, so infinitely my superior in every single moral quality, consented to be my wife. She has been my wise adviser and cheerful comforter throughout life, which without her would have been during a very long period a miserable one from ill-health. She has earned the love of every soul near her. LETTER 11. C. LYELL TO C. DARWIN. [July?, 1841?]. (11/1. Lyell started on his first visit to the United States in July, 1841, and was absent thirteen months. Darwin returned to London July 23rd, 1841, after a prolonged absence; he may, therefore, have missed seeing Lyell. Assuming the date 1841 to be correct, it would seem that the plan of living in the country was formed a year before it was actually carried out.) I have no doubt that your father did rightly in persuading you to stay [at Shrewsbury], but we were much disappointed in not seeing you before our start for a year's absence. I cannot tell you how often since your long illness I have missed the friendly intercourse which we had so frequently before, and on which I built more than ever after your marriage. It will not happen easily that twice in one's life, even in the large world of London, a congenial soul so occupied with precisely the same pursuits and with an independence enabling him to pursue them will fall so nearly in my way, and to have had it snatched from me with the prospect of your residence somewhat far off is a privation I feel as a very great one. I hope you will not, like Herschell, get far off from a railway. LETTER 12. TO CATHERINE DARWIN. (12/1. The following letter was written to his sister Catherine about two months before Charles Darwin settled at Down:--) Sunday [July 1842]. You must have been surprised at not having heard sooner about the house. Emma and I only returned yesterday afternoon from sleeping there. I will give you in detail, as my father would like, MY opinion on it--Emma's slightly differs. Position:--about 1/4 of a mile from the small village of Down in Kent--16 miles from St. Paul's--8 1/2 miles from station (with many trains) which station is only 10 from London. This is bad, as the drive from [i.e. on account of] the hills is long. I calculate we are two hours going from London Bridge. Village about forty houses with old walnut trees in the middle where stands an old flint church and the lanes meet. Inhabitants very respectable--infant school--grown up people great musicians--all touch their hats as in Wales and sit at their open doors in the evening; no high road leads through the village. The little pot-house where we slept is a grocer's shop, and the landlord is the carpenter--so you may guess the style of the village. There are butcher and baker and post-office. A carrier goes weekly to London and calls anywhere for anything in London and takes anything anywhere. On the road [from London] to the village, on a fine day the scenery is absolutely beautiful: from close to our house the view is very distant and rather beautiful, but the house being situated on a rather high tableland has somewhat of a desolate air. There is a most beautiful old farm-house, with great thatched barns and old stumps of oak trees, like that of Skelton, one field off. The charm of the place to me is that almost every field is intersected (as alas is ours) by one or more foot-paths. I never saw so many walks in any other county. The country is extraordinarily rural and quiet with narrow lanes and high hedges and hardly any ruts. It is really surprising to think London is only 16 miles off. The house stands very badly, close to a tiny lane and near another man's field. Our field is 15 acres and flat, looking into flat-bottomed valleys on both sides, but no view from the drawing-room, which faces due south, except on our flat field and bits of rather ugly distant horizon. Close in front there are some old (very productive) cherry trees, walnut trees, yew, Spanish chestnut, pear, old larch, Scotch fir and silver fir and old mulberry trees, [which] make rather a pretty group. They give the ground an old look, but from not flourishing much they also give it rather a desolate look. There are quinces and medlars and plums with plenty of fruit, and Morello cherries; but few apples. The purple magnolia flowers against the house. There is a really fine beech in view in our hedge. The kitchen garden is a detestable slip and the soil looks wretched from the quantity of chalk flints, but I really believe it is productive. The hedges grow well all round our field, and it is a noted piece of hayland. This year the crop was bad, but was bought, as it stood, for 2 pounds per acre--that is 30 pounds--the purchaser getting it in. Last year it was sold for 45 pounds--no manure was put on in the interval. Does not this sound well? Ask my father. Does the mulberry and magnolia show it is not very cold in winter, which I fear is the case? Tell Susan it is 9 miles from Knole Park and 6 from Westerham, at which places I hear the scenery is beautiful. There are many very odd views round our house--deepish flat-bottomed valley and nice farm-house, but big, white, ugly, fallow fields;--much wheat grown here. House ugly, looks neither old nor new--walls two feet thick--windows rather small--lower story rather low. Capital study 18 x 18. Dining-room 21 x 18. Drawing-room can easily be added to: is 21 x 15. Three stories, plenty of bedrooms. We could hold the Hensleighs and you and Susan and Erasmus all together. House in good repair. Mr. Cresy a few years ago laid out for the owner 1,500 pounds and made a new roof. Water-pipes over house--two bath-rooms--pretty good offices and good stable-yard, etc., and a cottage. I believe the price is about 2,200 pounds, and I have no doubt I shall get it for one year on lease first to try, so that I shall do nothing to the house at first (last owner kept three cows, one horse, and one donkey, and sold some hay annually from one field). I have no doubt if we complete the purchase I shall at least save 1,000 pounds over Westcroft, or any other house we have seen. Emma was at first a good deal disappointed, and at the country round the house; the day was gloomy and cold with N.E. wind. She likes the actual field and house better than I; the house is just situated as she likes for retirement, not too near or too far from other houses, but she thinks the country looks desolate. I think all chalk countries do, but I am used to Cambridgeshire, which is ten times worse. Emma is rapidly coming round. She was dreadfully bad with toothache and headache in the evening and Friday, but in coming back yesterday she was so delighted with the scenery for the first few miles from Down, that it has worked a great change in her. We go there again the first fine day Emma is able, and we then finally settle what to do. (12/2. The following fragmentary "Account of Down" was found among Mr. Darwin's papers after the publication of the "Life and Letters." It gives the impression that he intended to write a natural history diary after the manner of Gilbert White, but there is no evidence that this was actually the case.) 1843. May 15th.--The first peculiarity which strikes a stranger unaccustomed to a hilly chalk country is the valleys, with their steep rounded bottoms--not furrowed with the smallest rivulet. On the road to Down from Keston a mound has been thrown across a considerable valley, but even against this mound there is no appearance of even a small pool of water having collected after the heaviest rains. The water all percolates straight downwards. Ascertain average depth of wells, inclination of strata, and springs. Does the water from this country crop out in springs in Holmsdale or in the valley of the Thames? Examine the fine springs in Holmsdale. The valleys on this platform sloping northward, but exceedingly even, generally run north and south; their sides near the summits generally become suddenly more abrupt, and are fringed with narrow strips, or, as they are here called, "shaws" of wood, sometimes merely by hedgerows run wild. The sudden steepness may generally be perceived, as just before ascending to Cudham Wood, and at Green Hill, where one of the lanes crosses these valleys. These valleys are in all probability ancient sea-bays, and I have sometimes speculated whether this sudden steepening of the sides does not mark the edges of vertical cliffs formed when these valleys were filled with sea-water, as would naturally happen in strata such as the chalk. In most countries the roads and footpaths ascend along the bottoms of valleys, but here this is scarcely ever the case. All the villages and most of the ancient houses are on the platforms or narrow strips of flat land between the parallel valleys. Is this owing to the summits having existed from the most ancient times as open downs and the valleys having been filled up with brushwood? I have no evidence of this, but it is certain that most of the farmhouses on the flat land are very ancient. There is one peculiarity which would help to determine the footpaths to run along the summits instead of the bottom of the valleys, in that these latter in the middle are generally covered, even far more thickly than the general surface, with broken flints. This bed of flints, which gradually thins away on each side, can be seen from a long distance in a newly ploughed or fallow field as a whitish band. Every stone which ever rolls after heavy rain or from the kick of an animal, ever so little, all tend to the bottom of the valleys; but whether this is sufficient to account for their number I have sometimes doubted, and have been inclined to apply to the case Lyell's theory of solution by rain-water, etc., etc. The flat summit-land is covered with a bed of stiff red clay, from a few feet in thickness to as much, I believe, as twenty feet: this [bed], though lying immediately on the chalk, and abounding with great, irregularly shaped, unrolled flints, often with the colour and appearance of huge bones, which were originally embedded in the chalk, contains not a particle of carbonate of lime. This bed of red clay lies on a very irregular surface, and often descends into deep round wells, the origin of which has been explained by Lyell. In these cavities are patches of sand like sea-sand, and like the sand which alternates with the great beds of small pebbles derived from the wear-and-tear of chalk-flints, which form Keston, Hayes and Addington Commons. Near Down a rounded chalk-flint is a rarity, though some few do occur; and I have not yet seen a stone of distant origin, which makes a difference--at least to geological eyes--in the very aspect of the country, compared with all the northern counties. The chalk-flints decay externally, which, according to Berzelius ("Edin. New Phil. Journal," late number), is owing to the flints containing a small proportion of alkali; but, besides this external decay, the whole body is affected by exposure of a few years, so that they will not break with clean faces for building. This bed of red clay, which renders the country very slippery in the winter months from October to April, does not cover the sides of the valleys; these, when ploughed, show the white chalk, which tint shades away lower in the valley, as insensibly as a colour laid on by a painter's brush. Nearly all the land is ploughed, and is often left fallow, which gives the country a naked red look, or not unfrequently white, from a covering of chalk laid on by the farmers. Nobody seems at all aware on what principle fresh chalk laid on land abounding with lime does it any good. This, however, is said to have been the practice of the country ever since the period of the Romans, and at present the many white pits on the hill sides, which so frequently afford a picturesque contrast with the overhanging yew trees, are all quarried for this purpose. The number of different kinds of bushes in the hedgerows, entwined by traveller's joy and the bryonies, is conspicuous compared with the hedges of the northern counties. March 25th [1844?].--The first period of vegetation, and the banks are clothed with pale-blue violets to an extent I have never seen equalled, and with primroses. A few days later some of the copses were beautifully enlivened by Ranunculus auricomus, wood anemones, and a white Stellaria. Again, subsequently, large areas were brilliantly blue with bluebells. The flowers are here very beautiful, and the number of flowers; [and] the darkness of the blue of the common little Polygala almost equals it to an alpine gentian. There are large tracts of woodland, [cut down] about once every ten years; some of these enclosures seem to be very ancient. On the south side of Cudham Wood a beech hedge has grown to Brobdignagian size, with several of the huge branches crossing each other and firmly grafted together. Larks abound here, and their songs sound most agreeably on all sides; nightingales are common. Judging from an odd cooing note, something like the purring of a cat, doves are very common in the woods. June 25th.--The sainfoin fields are now of the most beautiful pink, and from the number of hive-bees frequenting them the humming noise is quite extraordinary. This humming is rather deeper than the humming overhead, which has been continuous and loud during all these last hot days over almost every field. The labourers here say it is made by "air-bees," and one man, seeing a wild bee in a flower different from the hive kind, remarked: "That, no doubt, is an air-bee." This noise is considered as a sign of settled fair weather. CHAPTER 1.II.--EVOLUTION, 1844-1858. (Chapter II./1. Since the publication of the "Life and Letters," Mr. Huxley's obituary notice of Charles Darwin has appeared. (Chapter II./2. "Proc. R. Soc." volume 44, 1888, and "Collected Essays (Darwiniana)," page 253, 1899.) This masterly paper is, in our opinion, the finest of the great series of Darwinian essays which we owe to Mr. Huxley. We would venture to recommend it to our readers as the best possible introduction to these pages. There is, however, one small point in which we differ from Mr. Huxley. In discussing the growth of Mr. Darwin's evolutionary views, Mr. Huxley quotes from the autobiography (Chapter II./3. "Life and Letters," I., page 82. Some account of the origin of his evolutionary views is given in a letter to Jenyns (Blomefield), "Life and Letters," II. page 34.) a passage in which the writer describes the deep impression made on his mind by certain groups of facts observed in South America. Mr. Huxley goes on: "The facts to which reference is here made were, without doubt, eminently fitted to attract the attention of a philosophical thinker; but, until the relations of the existing with the extinct species, and of the species of the different geographical areas with one another, were determined with some exactness, they afforded but an unsafe foundation for speculation. It was not possible that this determination should have been effected before the return of the "Beagle" to England; and thus the date (Chapter II./4. The date in question is July 1837, when he "opened first note-book on Transmutation of Species.') which Darwin (writing in 1837) assigns to the dawn of the new light which was rising in his mind, becomes intelligible." This seems to us inconsistent with Darwin's own statement that it was especially the character of the "species on Galapagos Archipelago" which had impressed him. (Chapter II./5. See "Life and Letters," I., page 276.) This must refer to the zoological specimens: no doubt he was thinking of the birds, but these he had himself collected in 1835 (Chapter II./6. He wrote in his "Journal," page 394, "My attention was first thoroughly aroused, by comparing together the numerous specimens shot by myself and several other parties on board," etc.), and no accurate determination of the forms was necessary to impress on him the remarkable characteristic species of the different islands. We agree with Mr. Huxley that 1837 is the date of the "new light which was rising in his mind." That the dawn did not come sooner seems to us to be accounted for by the need of time to produce so great a revolution in his conceptions. We do not see that Mr. Huxley's supposition as to the effect of the determination of species, etc., has much weight. Mr. Huxley quotes a letter from Darwin to Zacharias, "But I did not become convinced that species were mutable until, I think, two or three years [after 1837] had elapsed" (see Letter 278). This passage, which it must be remembered was written in 1877, is all but irreconcilable with the direct evidence of the 1837 note-book. A series of passages are quoted from it in the "Life and Letters," Volume II., pages 5 et seq., and these it is impossible to read without feeling that he was convinced of immutability. He had not yet attained to a clear idea of Natural Selection, and therefore his views may not have had, even to himself, the irresistible convincing power they afterwards gained; but that he was, in the ordinary sense of the word, convinced of the truth of the doctrine of evolution we cannot doubt. He thought it "almost useless" to try to prove the truth of evolution until the cause of change was discovered. And it is natural that in later life he should have felt that conviction was wanting till that cause was made out. (Chapter II./7. See "Charles Darwin, his Life told, etc." 1892, page 165.) For the purposes of the present chapter the point is not very material. We know that in 1842 he wrote the first sketch of his theory, and that it was greatly amplified in 1844. So that, at the date of the first letters of this chapter, we know that he had a working hypothesis of evolution which did not differ in essentials from that given in the "Origin of Species." To realise the amount of work that was in progress during the period covered by Chapter II., it should be remembered that during part of the time--namely, from 1846 to 1854--he was largely occupied by his work on the Cirripedes. (Chapter II./8. "Life and Letters," I. page 346.) This research would have fully occupied a less methodical workman, and even to those who saw him at work it seemed his whole occupation. Thus (to quote a story of Lord Avebury's) one of Mr. Darwin's children is said to have asked, in regard to a neighbour, "Then where does he do his barnacles?" as though not merely his father, but all other men, must be occupied on that group. Sir Joseph Hooker, to whom the first letter in this chapter is addressed, was good enough to supply a note on the origin of his intimacy with Mr. Darwin, and this is published in the "Life and Letters." (Chapter II./9. Ibid., II., page 19. See also "Nature," 1899, June 22nd, page 187, where some reminiscences are published, which formed part of Sir Joseph's speech at the unveiling of Darwin's statue in the Oxford Museum.) The close intercourse that sprang up between them was largely carried on by correspondence, and Mr. Darwin's letters to Sir Joseph have supplied most valuable biographical material. But it should not be forgotten that, quite apart from this, science owes much to this memorable friendship, since without Hooker's aid Darwin's great work would hardly have been carried out on the botanical side. And Sir Joseph did far more than supply knowledge and guidance in technical matters: Darwin owed to him a sympathetic and inspiriting comradeship which cheered and refreshed him to the end of his life. A sentence from a letter to Hooker written in 1845 shows, quite as well as more serious utterances, how quickly the acquaintance grew into friendship. "Farewell! What a good thing is community of tastes! I feel as if I had known you for fifty years. Adios." And in illustration of the permanence of the sympathetic bond between them, we quote a letter of 1881 written forty-two years after the first meeting with Sir Joseph in Trafalgar Square (see "Life and Letters," II., page 19). Mr. Darwin wrote: "Your letter has cheered me, and the world does not look a quarter so black this morning as it did when I wrote before. Your friendly words are worth their weight in gold.") LETTER 13. TO J.D. HOOKER. Down, Thursday [January 11th, 1844]. My dear Sir I must write to thank you for your last letter, and to tell you how much all your views and facts interest me. I must be allowed to put my own interpretation on what you say of "not being a good arranger of extended views"--which is, that you do not indulge in the loose speculations so easily started by every smatterer and wandering collector. I look at a strong tendency to generalise as an entire evil. What you say of Mr. Brown is humiliating; I had suspected it, but would not allow myself to believe in such heresy. Fitz-Roy gave him a rap in his preface (13/1. In the preface to the "Surveying Voyages of the 'Adventure' and the 'Beagle,' 1826-30, forming Volume I of the work, which includes the later voyage of the "Beagle," Captain Fitz-Roy wrote (March, 1839): "Captain King took great pains in forming and preserving a botanical collection, aided by a person embarked solely for that purpose. He placed this collection in the British Museum, and was led to expect that a first-rate botanist would have examined and described it; but he has been disappointed." A reference to Robert Brown's dilatoriness over King's collection occurs in the "Life and Letters," I., page 274, note.), and made him very indignant, but it seems a much harder one would not have been wasted. My cryptogamic collection was sent to Berkeley; it was not large. I do not believe he has yet published an account, but he wrote to me some year ago that he had described [the specimens] and mislaid all his descriptions. Would it not be well for you to put yourself in communication with him, as otherwise something will perhaps be twice laboured over? My best (though poor) collection of the cryptogams was from the Chonos Islands. Would you kindly observe one little fact for me, whether any species of plant, peculiar to any island, as Galapagos, St. Helena, or New Zealand, where there are no large quadrupeds, have hooked seeds--such hooks as, if observed here, would be thought with justness to be adapted to catch into wool of animals. Would you further oblige me some time by informing me (though I forget this will certainly appear in your "Antarctic Flora") whether in islands like St. Helena, Galapagos, and New Zealand, the number of families and genera are large compared with the number of species, as happens in coral islands, and as, I believe, in the extreme Arctic land. Certainly this is the case with marine shells in extreme Arctic seas. Do you suppose the fewness of species in proportion to number of large groups in coral islets is owing to the chance of seeds from all orders getting drifted to such new spots, as I have supposed. Did you collect sea-shells in Kerguelen-land? I should like to know their character. Your interesting letters tempt me to be very unreasonable in asking you questions; but you must not give yourself any trouble about them, for I know how fully and worthily you are employed. (13/2. The rest of the letter has been previously published in "Life and Letters," II., page 23.) Besides a general interest about the southern lands, I have been now ever since my return engaged in a very presumptuous work, and I know no one individual who would not say a very foolish one. I was so struck with the distribution of the Galapagos organisms, etc., and with the character of the American fossil mammifers, etc., that I determined to collect blindly every sort of fact which could bear any way on what are species. I have read heaps of agricultural and horticultural books, and have never ceased collecting facts. At last gleams of light have come, and I am almost convinced (quite contrary to the opinion I started with) that species are not (it is like confessing a murder) immutable. Heaven forfend me from Lamarck nonsense of a "tendency to progression," "adaptations from the slow willing of animals," etc.! But the conclusions I am led to are not widely different from his; though the means of change are wholly so. I think I have found out (here's presumption!) the simple way by which species become exquisitely adapted to various ends. You will now groan, and think to yourself, "on what a man have I been wasting my time and writing to." I should, five years ago, have thought so...(13/3. On the questions here dealt with see the interesting letter to Jenyns in the "Life and Letters," II., page 34.) LETTER 14. TO J.D. HOOKER. [November] 1844. ...What a curious, wonderful case is that of the Lycopodium! (14/1. Sir J.D. Hooker wrote, November 8, 1844: "I am firmly convinced (but not enough to print it) that L. Selago varies in Van Diemen's Land into L. varium. Two more different SPECIES (as they have hitherto been thought), per se cannot be conceived, but nowhere else do they vary into one another, nor does Selago vary at all in England.")...I suppose you would hardly have expected them to be more varying than a phanerogamic plant. I trust you will work the case out, and, even if unsupported, publish it, for you can surely do this with due caution. I have heard of some analogous facts, though on the smallest scale, in certain insects being more variable in one district than in another, and I think the same holds with some land-shells. By a strange chance I had noted to ask you in this letter an analogous question, with respect to genera, in lieu of individual species,--that is, whether you know of any case of a genus with most of its species being variable (say Rubus) in one continent, having another set of species in another continent non-variable, or not in so marked a manner. Mr. Herbert (14/2. No doubt Dean Herbert, the horticulturist. See "Life and Letters," I., page 343.) incidentally mentioned in a letter to me that the heaths at the Cape of Good Hope were very variable, whilst in Europe they are (?) not so; but then the species here are few in comparison, so that the case, even if true, is not a good one. In some genera of insects the variability appears to be common in distant parts of the world. In shells, I hope hereafter to get much light on this question through fossils. If you can help me, I should be very much obliged: indeed, all your letters are most useful to me. MONDAY:--Now for your first long letter, and to me quite as interesting as long. Several things are quite new to me in it--viz., for one, your belief that there are more extra-tropical than intra-tropical species. I see that my argument from the Arctic regions is false, and I should not have tried to argue against you, had I not fancied that you thought that equability of climate was the direct cause of the creation of a greater or lesser number of species. I see you call our climate equable; I should have thought it was the contrary. Anyhow, the term is vague, and in England will depend upon whether a person compares it with the United States or Tierra del Fuego. In my Journal (page 342) I see I state that in South Chiloe, at a height of about 1,000 feet, the forests had a Fuegian aspect: I distinctly recollect that at the sea-level in the middle of Chiloe the forest had almost a tropical aspect. I should like much to hear, if you make out, whether the N. or S. boundaries of a plant are the most restricted; I should have expected that the S. would be, in the temperate regions, from the number of antagonist species being greater. N.B. Humboldt, when in London, told me of some river (14/3. The Obi (see "Flora Antarctica," page 211, note). Hooker writes: "Some of the most conspicuous trees attain either of its banks, but do not cross them.") in N.E. Europe, on the opposite banks of which the flora was, on the same soil and under same climate, widely different! I forget (14/4. The last paragraph is published in "Life and Letters," II., page 29.) my last letter, but it must have been a very silly one, as it seems I gave my notion of the number of species being in great degree governed by the degree to which the area had been often isolated and divided. I must have been cracked to have written it, for I have no evidence, without a person be willing to admit all my views, and then it does follow. (14/5. The remainder of the foregoing letter is published in the "Life and Letters," II., page 29. It is interesting as giving his views on the mutability of species. Thus he wrote: "With respect to books on this subject, I do not know any systematical ones, except Lamarck's, which is veritable rubbish; but there are plenty, as Lyell, Pritchard, etc., on the view of the immutability." By "Pritchard" is no doubt intended James Cowles "Prichard," author of the "Physical History of Mankind." Prof. Poulton has given in his paper, "A remarkable Anticipation of Modern Views on Evolution" (14/6. "Science Progress," Volume I., April 1897, page 278.), an interesting study of Prichard's work. He shows that Prichard was in advance of his day in his views on the non-transmission of acquired characters. Prof. Poulton also tries to show that Prichard was an evolutionist. He allows that Prichard wrote with hesitation, and that in the later editions of his book his views became weaker. But, even with these qualifications, we think that Poulton has unintentionally exaggerated the degree to which Prichard believed in evolution. One of Prichard's strongest sentences is quoted by Poulton (loc. cit., page 16); it occurs in the "Physical History of Mankind," Ed. 2, Volume II., page 570:-- "Is it not probable that the varieties which spring up within the limits of particular species are further adaptations of structure to the circumstances under which the tribe is destined to exist? Varieties branch out from the common form of a species, just as the forms of species deviate from the common type of a genus. Why should the one class of phenomena be without end or utility, a mere effect of contingency or chance, more than the other?" If this passage, and others similar to it, stood alone, we might agree with Prof. Poulton; but this is impossible when we find in Volume I. of the same edition, page 90, the following uncompromising statement of immutability:-- "The meaning attached to the term species, in natural history, is very simple and obvious. It includes only one circumstance--namely, an original distinctness and constant transmission of any character. A race of animals, or plants, marked by any peculiarities of structure which have always been constant and undeviating, constitutes a species." On page 91, in speaking of the idea that the species which make up a genus may have descended from a common form, he says:-- "There must, indeed, be some principle on which the phenomena of resemblance, as well as those of diversity, may be explained; and the reference of several forms to a common type seems calculated to suggest the idea of some original affinity; but, as this is merely a conjecture, it must be kept out of sight when our inquiries respect matters of fact only." This view is again given in Volume II., page 569, where he asks whether we should believe that "at the first production of a genus, when it first grew into existence, some slight modification in the productive causes stamped it originally with all these specific diversities? Or is it most probable that the modification was subsequent to its origin, and that the genus at its first creation was one and uniform, and afterwards became diversified by the influence of external agents?" He concludes that "the former of these suppositions is the conclusion to which we are led by all that can be ascertained respecting the limits of species, and the extent of variation under the influence of causes at present existing and operating." In spite of the fact that Prichard did not carry his ideas to their logical conclusion, it may perhaps excite surprise that Mr. Darwin should have spoken of him as absolutely on the side of immutability. We believe it to be partly accounted for (as Poulton suggests) by the fact that Mr. Darwin possessed only the third edition (1836 and 1837) and the fourth edition (1841-51). (14/7. The edition of 1841-51 consists of reprints of the third edition and three additional volumes of various dates. Volumes I. and II. are described in the title-page as the fourth edition; Volumes III. and IV. as the third edition, and Volume V. has no edition marked in the title.) In neither of these is the evolutionary point of view so strong as in the second edition. We have gone through all the passages marked by Mr. Darwin for future reference in the third and fourth editions, and have been only able to find the following, which occurs in the third edition (Volume I., 1836, page 242) (14/8. There is also (ed. 1837, Volume II., page 344) a vague reference to Natural Selection, of which the last sentence is enclosed in pencil in inverted commas, as though Mr. Darwin had intended to quote it: "In other parts of Africa the xanthous variety [of man] often appears, but does not multiply. Individuals thus characterised are like seeds which perish in an uncongenial soil.") "The variety in form, prevalent among all organised productions of nature, is found to subsist between individual beings of whatever species, even when they are offspring of the same parents. Another circumstance equally remarkable is the tendency which exists in almost every tribe, whether of animals or of plants, to transmit to their offspring and to perpetuate in their race all individual peculiarities which may thus have taken their rise. These two general facts in the economy of organised beings lay a foundation for the existence of diversified races, originating from the same primitive stock and within the limits of identical species." On the following page (page 243) a passage (not marked by Mr. Darwin) emphasises the limitation which Prichard ascribed to the results of variation and inheritance:-- "Even those physiologists who contend for what is termed the indefinite nature of species admit that they have limits at present and under ordinary circumstances. Whatever diversities take place happen without breaking in upon the characteristic type of the species. This is transmitted from generation to generation: goats produce goats, and sheep, sheep." The passage on page 242 occurs in the reprint of the 1836-7 edition which forms part of the 1841-51 edition, but is not there marked by Mr. Darwin. He notes at the end of Volume I. of the 1836-7 edition: "March, 1857. I have not looked through all these [i.e. marked passages], but I have gone through the later edition"; and a similar entry is in Volume II. of the third edition. It is therefore easy to understand how he came to overlook the passage on page 242 when he began the fuller statement of his species theory which is referred to in the "Life and Letters" as the "unfinished book." In the historical sketch prefixed to the "Origin of Species" writers are named as precursors whose claims are less strong than Prichard's, and it is certain that Mr. Darwin would have given an account of him if he had thought of him as an evolutionist. The two following passages will show that Mr. Darwin was, from his knowledge of Prichard's books, justified in classing him among those who did not believe in the mutability of species: "The various tribes of organised beings were originally placed by the Creator in certain regions, for which they are by their nature peculiarly adapted. Each species had only one beginning in a single stock: probably a single pair, as Linnaeus supposed, was first called into being in some particular spot, and the progeny left to disperse themselves to as great a distance from the original centre of their existence as the locomotive powers bestowed on them, or their capability of bearing changes of climate and other physical agencies, may have enabled them to wander." (14/9. Prichard, third edition, 1836-7, Volume I., page 96.) The second passage is annotated by Mr. Darwin with a shower of exclamation marks: "The meaning attached to the term SPECIES in natural history is very definite and intelligible. It includes only the following conditions--namely, separate origin and distinctness of race, evinced by the constant transmission of some characteristic peculiarity of organisation. A race of animals or of plants marked by any peculiar character which has always been constant and undeviating constitutes a species; and two races are considered as specifically different, if they are distinguished from each other by some characteristic which one cannot be supposed to have acquired, or the other to have lost through any known operation of physical causes; for we are hence led to conclude that the tribes thus distinguished have not descended from the same original stock." (14/10. Prichard, ed. 1836-7, Volume I., page 106. This passage is almost identical with that quoted from the second edition, Volume I., page 90. The latter part, from "and two races...," occurs in the second edition, though not quoted above.) As was his custom, Mr. Darwin pinned at the end of the first volume of the 1841-51 edition a piece of paper containing a list of the pages where marked passages occur. This paper bears, written in pencil, "How like my book all this will be!" The words appear to refer to Prichard's discussion on the dispersal of animals and plants; they certainly do not refer to the evolutionary views to be found in the book.) LETTER 15. TO J.D. HOOKER. Down [1844]. Thank you exceedingly for your long letter, and I am in truth ashamed of the time and trouble you have taken for me; but I must some day write again to you on the subject of your letter. I will only now observe that you have extended my remark on the range of species of shells into the range of genera or groups. Analogy from shells would only go so far, that if two or three species...were found to range from America to India, they would be found to extend through an unusual thickness of strata--say from the Upper Cretaceous to its lowest bed, or the Neocomian. Or you may reverse it and say those species which range throughout the whole Cretaceous, will have wide ranges: viz., from America through Europe to India (this is one actual case with shells in the Cretaceous period). LETTER 16. TO J.D. HOOKER. Down [1845]. I ought to have written sooner to say that I am very willing to subscribe 1 pound 1 shilling to the African man (though it be murder on a small scale), and will send you a Post-office-order payable to Kew, if you will be so good as to take charge of it. Thanks for your information about the Antarctic Zoology; I got my numbers when in Town on Thursday: would it be asking your publisher to take too much trouble to send your Botany ["Flora Antarctica," by J.D. Hooker, 1844] to the Athenaeum Club? he might send two or three numbers together. I am really ashamed to think of your having given me such a valuable work; all I can say is that I appreciate your present in two ways--as your gift, and for its great use to my species-work. I am very glad to hear that you mean to attack this subject some day. I wonder whether we shall ever be public combatants; anyhow, I congratulate myself in a most unfair advantage of you, viz., in having extracted more facts and views from you than from any one other person. I daresay your explanation of polymorphism on volcanic islands may be the right one; the reason I am curious about it is, the fact of the birds on the Galapagos being in several instances very fine-run species--that is, in comparing them, not so much one with another, as with their analogues from the continent. I have somehow felt, like you, that an alpine form of a plant is not a true variety; and yet I cannot admit that the simple fact of the cause being assignable ought to prevent its being called a variety; every variation must have some cause, so that the difference would rest on our knowledge in being able or not to assign the cause. Do you consider that a true variety should be produced by causes acting through the parent? But even taking this definition, are you sure that alpine forms are not inherited from one, two, or three generations? Now, would not this be a curious and valuable experiment (16/1. For an account of work of this character, see papers by G. Bonnier in the "Revue Generale," Volume II., 1890; "Ann. Sc. Nat." Volume XX.; "Revue Generale," Volume VII.), viz., to get seeds of some alpine plant, a little more hairy, etc., etc., than its lowland fellow, and raise seedlings at Kew: if this has not been done, could you not get it done? Have you anybody in Scotland from whom you could get the seeds? I have been interested by your remarks on Senecia and Gnaphalium: would it not be worth while (I should be very curious to hear the result) to make a short list of the generally considered variable or polymorphous genera, as Rosa, Salix, Rubus, etc., etc., and reflect whether such genera are generally mundane, and more especially whether they have distinct or identical (or closely allied) species in their different and distant habitats. Don't forget me, if you ever stumble on cases of the same species being MORE or LESS variable in different countries. With respect to the word "sterile" as used for male or polleniferous flowers, it has always offended my ears dreadfully; on the same principle that it would to hear a potent stallion, ram or bull called sterile, because they did not bear, as well as beget, young. With respect to your geological-map suggestion, I wish with all my heart I could follow it; but just reflect on the number of measurements requisite; why, at present it could not be done even in England, even with the assumption of the land having simply risen any exact number of feet. But subsidence in most cases has hopelessly complexed the problem: see what Jordanhill-Smith (16/2. James Smith, of Jordan Hill, author of a paper "On the Geology of Gibraltar" ("Quart. Journ. Geol. Soc." Volume II., page 41, 1846).) says of the dance up and down, many times, which Gibraltar has had all within the recent period. Such maps as Lyell (16/3. "Principles of Geology," 1875, Volume I., Plate I, page 254.) has published of sea and land at the beginning of the Tertiary period must be excessively inaccurate: it assumes that every part on which Tertiary beds have not been deposited, must have then been dry land,--a most doubtful assumption. I have been amused by Chambers v. Hooker on the K. Cabbage. I see in the "Explanations" (the spirit of which, though not the facts, ought to shame Sedgwick) that "Vestiges" considers all land-animals and plants to have passed from marine forms; so Chambers is quite in accordance. Did you hear Forbes, when here, giving the rather curious evidence (from a similarity in error) that Chambers must be the author of the "Vestiges": your case strikes me as some confirmation. I have written an unreasonably long and dull letter, so farewell. (16/4. "Explanations: A Sequel to the Vestiges of the Natural History of Creation" was published in 1845, after the appearance of the fourth edition of the "Vestiges," by way of reply to the criticisms on the original book. The "K. cabbage" referred to at the beginning of the paragraph is Pringlea antiscorbutica," the "Kerguelen Cabbage" described by Sir J.D. Hooker in his "Flora Antarctica." What Chambers wrote on this subject we have not discovered. The mention of Sedgwick is a reference to his severe review of the "Vestiges" in the "Edinburgh Review," 1845, volume 82, page 1. Darwin described it as savouring "of the dogmatism of the pulpit" ("Life and Letters," I., page 344). Mr. Ireland's edition of the "Vestiges" (1844), in which Robert Chambers was first authentically announced as the author, contains (page xxix) an extract from a letter written by Chambers in 1860, in which the following passage occurs, "The April number of the 'Edinburgh Review"' (1860) makes all but a direct amende for the abuse it poured upon my work a number of years ago." This is the well-known review by Owen, to which references occur in the "Life and Letters," II., page 300. The amende to the "Vestiges" is not so full as the author felt it to be; but it was clearly in place in a paper intended to belittle the "Origin"; it also gave the reviewer (page 511) an opportunity for a hit at Sedgwick and his 1845 review.) LETTER 17. TO L. BLOMEFIELD [JENYNS]. Down. February 14th [1845]. I have taken my leisure in thanking you for your last letter and discussion, to me very interesting, on the increase of species. Since your letter, I have met with a very similar view in Richardson, who states that the young are driven away by the old into unfavourable districts, and there mostly perish. When one meets with such unexpected statistical returns on the increase and decrease and proportion of deaths and births amongst mankind, and in this well-known country of ours, one ought not to be in the least surprised at one's ignorance, when, where, and how the endless increase of our robins and sparrows is checked. Thanks for your hints about terms of "mutation," etc.; I had some suspicions that it was not quite correct, and yet I do not see my way to arrive at any better terms. It will be years before I publish, so that I shall have plenty of time to think of better words. Development would perhaps do, only it is applied to the changes of an individual during its growth. I am, however, very glad of your remark, and will ponder over it. We are all well, wife and children three, and as flourishing as this horrid, house-confining, tempestuous weather permits. LETTER 18. TO J.D. HOOKER. Down [1845]. I hope you are getting on well with your lectures, and that you have enjoyed some pleasant walks during the late delightful weather. I write to tell you (as perhaps you might have had fears on the subject) that your books have arrived safely. I am exceedingly obliged to you for them, and will take great care of them; they will take me some time to read carefully. I send to-day the corrected MS. of the first number of my "Journal" (18/1. In 1842 he had written to his sister: "Talking of money, I reaped the other day all the profit which I shall ever get from my "Journal" ["Journal of Researches, etc."] which consisted in paying Mr. Colburn 21 pounds 10 shillings for the copies which I presented to different people; 1,337 copies have been sold. This is a comfortable arrangement, is it not?" He was proved wrong in his gloomy prophecy, as the second edition was published by Mr. Murray in 1845.) in the Colonial Library, so that if you chance to know of any gross mistake in the first 214 pages (if you have my "Journal"), I should be obliged to you to tell me. Do not answer this for form's sake; for you must be very busy. We have just had the Lyells here, and you ought to have a wife to stop your working too much, as Mrs. Lyell peremptorily stops Lyell. LETTER 19. TO J.D. HOOKER. (19/1. Sir J.D. Hooker's letters to Mr. Darwin seem to fix the date as 1845, while the reference to Forbes' paper indicates 1846.) Down [1845-1846]. I am particularly obliged for your facts about solitary islands having several species of peculiar genera; it knocks on the head some analogies of mine; the point stupidly never occurred to me to ask about. I am amused at your anathemas against variation and co.; whatever you may be pleased to say, you will never be content with simple species, "as they are." I defy you to steel your mind to technicalities, like so many of our brother naturalists. I am much pleased that I thought of sending you Forbes' article. (19/2. E. Forbes' celebrated paper "Memoirs of the Geological Survey of Great Britain," Volume I., page 336, 1846. In Lyell's "Principles," 7th Edition, 1847, page 676, he makes a temperate claim of priority, as he had already done in a private letter of October 14th, 1846, to Forbes ("Life of Sir Charles Lyell," 1881, Volume II., page 106) both as regards the Sicilian flora and the barrier effect of mountain-chains. See Letter 20 for a note on Forbes.) I confess I cannot make out the evidence of his time-notions in distribution, and I cannot help suspecting that they are rather vague. Lyell preceded Forbes in one class of speculation of this kind: for instance, in his explaining the identity of the Sicily Flora with that of South Italy, by its having been wholly upraised within the recent period; and, so I believe, with mountain-chains separating floras. I do not remember Humboldt's fact about the heath regions. Very curious the case of the broom; I can tell you something analogous on a small scale. My father, when he built his house, sowed many broom-seeds on a wild bank, which did not come up, owing, as it was thought, to much earth having been thrown over them. About thirty-five years afterwards, in cutting a terrace, all this earth was thrown up, and now the bank is one mass of broom. I see we were in some degree talking to cross-purposes; when I said I did [not] much believe in hybridising to any extent, I did not mean at all to exclude crossing. It has long been a hobby of mine to see in how many flowers such crossing is probable; it was, I believe, Knight's view, originally, that every plant must be occasionally crossed. (19/3. See an article on "The Knight-Darwin law" by Francis Darwin in "Nature," October 27th, 1898, page 630.) I find, however, plenty of difficulty in showing even a vague probability of this; especially in the Leguminosae, though their [structure?] is inimitably adapted to favour crossing, I have never yet met with but one instance of a NATURAL MONGREL (nor mule?) in this family. I shall be particularly curious to hear some account of the appearance and origin of the Ayrshire Irish Yew. And now for the main object of my letter: it is to ask whether you would just run your eye over the proof of my Galapagos chapter (19/4. In the second edition of the "Naturalist's Voyage."), where I mention the plants, to see that I have made no blunders, or spelt any of the scientific names wrongly. As I daresay you will so far oblige me, will you let me know a few days before, when you leave Edinburgh and how long you stay at Kinnordy, so that my letter might catch you. I am not surprised at my collection from James Island differing from others, as the damp upland district (where I slept two nights) is six miles from the coast, and no naturalist except myself probably ever ascended to it. Cuming had never even heard of it. Cuming tells me that he was on Charles, James, and Albemarle Islands, and that he cannot remember from my description the Scalesia, but thinks he could if he saw a specimen. I have no idea of the origin of the distribution of the Galapagos shells, about which you ask. I presume (after Forbes' excellent remarks on the facilities by which embryo-shells are transported) that the Pacific shells have been borne thither by currents; but the currents all run the other way. (PLATE: EDWARD FORBES 1844? From a photograph by Hill & Adamson.) LETTER 20. EDWARD FORBES TO C. DARWIN. (20/1. Edward Forbes was at work on his celebrated paper in the "Geological Survey Memoirs" for 1846. We have not seen the letter of Darwin's to which this is a reply, nor, indeed, any of his letters to Forbes. The date of the letter is fixed by Forbes's lecture given at the Royal Institution on February 27th, 1846 (according to L. Horner's privately printed "Memoirs," II., page 94.)) Wednesday. 3, Southwark Street, Hyde Park. [1846]. Dear Darwin To answer your very welcome letter, so far from being a waste of time, is a gain, for it obliges me to make myself clear and understood on matters which I have evidently put forward imperfectly and with obscurity. I have devoted the whole of this week to working and writing out the flora question, for I now feel strong enough to give my promised evening lecture on it at the Royal Institution on Friday, and, moreover, wish to get it in printable form for the Reports of our Survey. Therefore at no time can I receive or answer objections with more benefit than now. From the hurry and pressure which unfortunately attend all my movements and doings I rarely have time to spare, in preparing for publication, to do more than give brief and unsatisfactory abstracts, which I fear are often extremely obscure. Now for your objections--which have sprung out of my own obscurities. I do not argue in a circle about the Irish case, but treat the botanical evidence of connection and the geological as distinct. The former only I urged at Cambridge; the latter I have not yet publicly maintained. My Cambridge argument (20/2. "On the Distribution of Endemic Plants," by E. Forbes, "Brit. Assoc. Rep." 1845 (Cambridge), page 67.) was this: That no known currents, whether of water or air, or ordinary means of transport (20/3. Darwin's note on transportation (found with Forbes' letter): "Forbes' arguments, from several Spanish plants in Ireland not being transported, not sound, because sea-currents and air ditto and migration of birds in SAME LINES. I have thought not-transportation the greatest difficulty. Now we see how many seeds every plant and tree requires to be regularly propagated in its own country, for we cannot think the great number of seeds superfluous, and therefore how small is the chance of here and there a solitary seedling being preserved in a well-stocked country."), would account for the little group of Asturian plants--few as to species, but playing a conspicuous part in the vegetation--giving a peculiar botanical character to the south of Ireland; that, as I had produced evidence of the other floras of our islands, i.e. the Germanic, the Cretaceous, and the Devonian (these terms used topographically, not geologically) having been acquired by migration over continuous land (the glacial or alpine flora I except for the present--as ice-carriage might have played a great part in its introduction)--I considered it most probable, and maintained, that the introduction of that Irish flora was also effected by the same means. I held also that the character of this flora was more southern and more ancient than that of any of the others, and that its fragmentary and limited state was probably due to the plants composing it having (from their comparative hardiness--heaths, saxifrages, etc.) survived the destroying influence of the glacial epoch. My geological argument now is as follows: half the Mediterranean islands, or more, are partly--in some cases (as Malta) wholly--composed of the upheaved bed of the Miocene sea; so is a great part of the south of France from Bordeaux to Montpellier; so is the west of Portugal; and we find the corresponding beds with the same fossils (Pecten latissimus, etc.) in the Azores. So general an upheaval seems to me to indicate the former existence of a great post-Miocene land [in] the region of what is usually called the Mediterranean flora. (Everywhere these Miocene islands, etc., bear a flora of true type.) If this land existed, it did not extend to America, for the fossils of the Miocene of America are representative and not identical. Where, then, was the edge or coast-line of it, Atlantic-wards? Look at the form and constancy of the great fucus-bank, and consider that it is a Sargassum bank, and that the Sargassum there is in an abnormal condition, and that the species of this genus of fuci are essentially ground-growers, and then see the probability of this bank having originated on a line of ancient coast. Now, having thus argued independently, first on my flora and second on the geological evidences of land in the quarter required, I put the two together to bear up my Irish case. I cannot admit the Sargassum case to be parallel with that of Confervae or Oscillatoria. I think I have evidence from the fossils of the boulder formations in Ireland that if such Miocene land existed it must have been broken up or partially broken up at the epoch of the glacial or boulder period. All objections thankfully received. Ever most sincerely, EDWARD FORBES. LETTER 21. TO L. JENYNS (BLOMEFIELD). Down. [1846]. I am much obliged for your note and kind intended present of your volume. (21/1. No doubt the late Mr. Blomefield's "Observations in Natural History." See "Life and Letters," II., page 31.) I feel sure I shall like it, for all discussions and observations on what the world would call trifling points in Natural History always appear to me very interesting. In such foreign periodicals as I have seen, there are no such papers as White, or Waterton, or some few other naturalists in Loudon's and Charlesworth's Journal, would have written; and a great loss it has always appeared to me. I should have much liked to have met you in London, but I cannot leave home, as my wife is recovering from a rather sharp fever attack, and I am myself slaving to finish my S. American Geology (21/2. "Geological Observations in South America" (London), 1846.), of which, thanks to all Plutonic powers, two-thirds are through the press, and then I shall feel a comparatively free man. Have you any thoughts of Southampton? (21/3. The British Association met at Southampton in 1846.) I have some vague idea of going there, and should much enjoy meeting you. LETTER 22. TO J.D. HOOKER. Shrewsbury [end of February 1846]. I came here on account of my father's health, which has been sadly failing of late, but to my great joy he has got surprisingly better...I had not heard of your botanical appointment (22/1. Sir Joseph was appointed Botanist to the Geological Survey in 1846.), and am very glad of it, more especially as it will make you travel and give you change of work and relaxation. Will you some time have to examine the Chalk and its junction with London Clay and Greensand? If so our house would be a good central place, and my horse would be at your disposal. Could you not spin a long week out of this examination? it would in truth delight us, and you could bring your papers (like Lyell) and work at odd times. Forbes has been writing to me about his subsidence doctrines; I wish I had heard his full details, but I have expressed to him in my ignorance my objections, which rest merely on its too great hypothetical basis; I shall be curious, when I meet him, to hear what he says. He is also speculating on the gulf-weed. I confess I cannot appreciate his reasoning about his Miocene continent, but I daresay it is from want of knowledge. You allude to the Sicily flora not being peculiar, and this being caused by its recent elevation (well established) in the main part: you will find Lyell has put forward this very clearly and well. The Apennines (which I was somewhere lately reading about) seems a very curious case. I think Forbes ought to allude a little to Lyell's (22/2. See Letter 19.) work on nearly the same subject as his speculations; not that I mean that Forbes wishes to take the smallest credit from him or any man alive; no man, as far as I see, likes so much to give credit to others, or more soars above the petty craving for self-celebrity. If you come to any more conclusions about polymorphism, I should be very glad to hear the result: it is delightful to have many points fermenting in one's brain, and your letters and conclusions always give one plenty of this same fermentation. I wish I could even make any return for all your facts, views, and suggestions. LETTER 23. TO J.D. HOOKER. (23/1. The following extract gives the germ of what developed into an interesting discussion in the "Origin" (Edition I., page 147). Darwin wrote, "I suspect also that some cases of compensation which have been advanced and likewise some other facts, may be merged under a more general principle: namely, that natural selection is continually trying to economise in every part of the organism." He speaks of the general belief of botanists in compensation, but does not quote any instances.) [September 1846]. Have you ever thought of G. St. Hilaire's "loi de balancement" (23/2. According to Darwin ("Variation of Animals and Plants," 2nd edition, II., page 335) the law of balancement was propounded by Goethe and Geoffroy Saint-Hilaire (1772-1844) nearly at the same time, but he gives no reference to the works of these authors. It appears, however, from his son Isidore's "Vie, Travaux etc., d'Etienne Geoffroy Saint-Hilaire," Paris 1847, page 214, that the law was given in his "Philosophie Anatomique," of which the first part was published in 1818. Darwin (ibid.) gives some instances of the law holding good in plants.), as applied to plants? I am well aware that some zoologists quite reject it, but it certainly appears to me that it often holds good with animals. You are no doubt aware of the kind of facts I refer to, such as great development of canines in the carnivora apparently causing a diminution--a compensation or balancement--in the small size of premolars, etc. I have incidentally noticed some analogous remarks on plants, but have never seen it discussed by botanists. Can you think of cases in any one species in genus, or genus in family, with certain parts extra developed, and some adjoining parts reduced? In varieties of the same species double flowers and large fruits seem something of this--want of pollen and of seeds balancing with the increased number of petals and development of fruit. I hope we shall see you here this autumn. (24/1. In this year (1847) Darwin wrote a short review of Waterhouse's "Natural History of the Mammalia," of which the first volume had appeared. It was published in "The Annals and Magazine of Natural History," Volume XIX., page 53. The following sentence is the only one which shows even a trace of evolution: "whether we view classification as a mere contrivance to convey much information in a single word, or as something more than a memoria technica, and as connected with the laws of creation, we cannot doubt that where such important differences in the generative and cerebral systems, as distinguish the Marsupiata from the Placentata, run through two series of animals, they ought to be arranged under heads of equal value." A characteristic remark occurs in reference to Geographical Distribution, "that noble subject of which we as yet but dimly see the full bearing." The following letter seems to be of sufficient interest to be published in spite of the obscurities caused by the want of date. It seems to have been written after 1847, in which year a dispute involving Dr. King and several "arctic gentlemen" was carried on in the "Athenaeum." Mr. Darwin speaks of "Natural History Instructions for the present expedition." This may possibly refer to the "Admiralty Manual of Scientific Enquiry" (1849), for it is clear, from the prefatory memorandum of the Lords of the Admiralty, that they believed the manual would be of use in the forthcoming expeditions in search of Sir John Franklin.) LETTER 24. TO E. CRESY. (24/2. Mr. Cresy was, we believe, an architect: his friendship with Mr. Darwin dates from the settlement at Down.) Down [after 1847]. Although I have never particularly attended to the points in dispute between Dr. (Richard) King and the other Arctic gentlemen, yet I have carefully read all the articles in the "Athenaeum," and took from them much the same impression as you convey in your letter, for which I thank you. I believe that old sinner, Sir J. Barrow (24/3. Sir John Barrow, (1764-1848): Secretary to the Admiralty. has been at the bottom of all the money wasted over the naval expeditions. So strongly have I felt on this subject, that, when I was appointed on a committee for Nat. Hist. instructions for the present expedition, had I been able to attend I had resolved to express my opinion on the little advantage, comparatively to the expense, gained by them. There have been, I believe, from the beginning eighteen expeditions; this strikes me as monstrous, considering how little is known, for instance, on the interior of Australia. The country has paid dear for Sir John's hobbyhorse. I have very little doubt that Dr. King is quite right in the advantage of land expeditions as far as geography is concerned; and that is now the chief object. (24/4. This sentence would imply that Darwin thought it hopeless to rescue Sir J. Franklin's expedition. If so, the letter must be, at least, as late as 1850. If the eighteen expeditions mentioned above are "search expeditions," it would also bring the date of the letter to 1850.) LETTER 25. TO RICHARD OWEN. Down [March 26th, 1848]. My dear Owen I do not know whether your MS. instructions are sent in; but even if they are not sent in, I daresay what I am going to write will be absolutely superfluous (25/1. The results of Mr. Darwin's experience given in the above letter were embodied by Prof. Owen in the section "On the Use of the Microscope on Board Ship," forming part of the article "Zoology" in the "Manual of Scientific Enquiry, Prepared for the Use of Her Majesty's Navy" (London, 1849).), but I have derived such infinitely great advantage from my new simple microscope, in comparison with the one which I used on board the "Beagle," and which was recommended to me by R. Brown ("Life and Letters," I., page 145.), that I cannot forego the mere chance of advantage of urging this on you. The leading point of difference consists simply in having the stage for saucers very large and fixed. Mine will hold a saucer three inches in inside diameter. I have never seen such a microscope as mine, though Chevalier's (from whose plan many points of mine are taken), of Paris, approaches it pretty closely. I fully appreciate the utter ABSURDITY of my giving you advice about means of dissecting; but I have appreciated myself the enormous disadvantage of having worked with a bad instrument, though thought a few years since the best. Please to observe that without you call especial attention to this point, those ignorant of Natural History will be sure to get one of the fiddling instruments sold in shops. If you thought fit, I would point out the differences, which, from my experience, make a useful microscope for the kind of dissection of the invertebrates which a person would be likely to attempt on board a vessel. But pray again believe that I feel the absurdity of this letter, and I write merely from the chance of yourself, possessing great skill and having worked with good instruments, [not being] possibly fully aware what an astonishing difference the kind of microscope makes for those who have not been trained in skill for dissection under water. When next I come to town (I was prevented last time by illness) I must call on you, and report, for my own satisfaction, a really (I think) curious point I have made out in my beloved barnacles. You cannot tell how much I enjoyed my talk with you here. Ever, my dear Owen, Yours sincerely, C. DARWIN. P.S.--If I do not hear, I shall understand that my letter is superfluous. Smith and Beck were so pleased with the simple microscope they made for me, that they have made another as a model. If you are consulted by any young naturalists, do recommend them to look at this. I really feel quite a personal gratitude to this form of microscope, and quite a hatred to my old one. LETTER 26. TO J.S. HENSLOW. Down [April 1st, 1848.] Thank you for your note and giving me a chance of seeing you in town; but it was out of my power to take advantage of it, for I had previously arranged to go up to London on Monday. I should have much enjoyed seeing you. Thanks also for your address (26/1. An introductory lecture delivered in March 1848 at the first meeting of a Society "for giving instructions to the working classes in Ipswich in various branches of science, and more especially in natural history" ("Memoir of the Rev. J.S. Henslow," by Leonard Jenyns, page 150.), which I like very much. The anecdote about Whewell and the tides I had utterly forgotten; I believe it is near enough to the truth. I rather demur to one sentence of yours--viz., "However delightful any scientific pursuit may be, yet, if it should be wholly unapplied, it is of no more use than building castles in the air." Would not your hearers infer from this that the practical use of each scientific discovery ought to be immediate and obvious to make it worthy of admiration? What a beautiful instance chloroform is of a discovery made from purely scientific researches, afterwards coming almost by chance into practical use! For myself I would, however, take higher ground, for I believe there exists, and I feel within me, an instinct for truth, or knowledge or discovery, of something of the same nature as the instinct of virtue, and that our having such an instinct is reason enough for scientific researches without any practical results ever ensuing from them. You will wonder what makes me run on so, but I have been working very hard for the last eighteen months on the anatomy, etc., of the Cirripedia (on which I shall publish a monograph), and some of my friends laugh at me, and I fear the study of the Cirripedia will ever remain "wholly unapplied," and yet I feel that such study is better than castle-building. LETTER 27. TO J.D. HOOKER, at Dr. Falconer's, Botanic Garden, Calcutta. Down, May 10th, 1848. I was indeed delighted to see your handwriting; but I felt almost sorry when I beheld how long a letter you had written. I know that you are indomitable in work, but remember how precious your time is, and do not waste it on your friends, however much pleasure you may give them. Such a letter would have cost me half-a-day's work. How capitally you seem going on! I do envy you the sight of all the glorious vegetation. I am much pleased and surprised that you have been able to observe so much in the animal world. No doubt you keep a journal, and an excellent one it will be, I am sure, when published. All these animal facts will tell capitally in it. I can quite comprehend the difficulty you mention about not knowing what is known zoologically in India; but facts observed, as you will observe them, are none the worse for reiterating. Did you see Mr. Blyth in Calcutta? He would be a capital man to tell you what is known about Indian Zoology, at least in the Vertebrata. He is a very clever, odd, wild fellow, who will never do what he could do, from not sticking to any one subject. By the way, if you should see him at any time, try not to forget to remember me very kindly to him; I liked all I saw of him. Your letter was the very one to charm me, with all its facts for my Species-book, and truly obliged I am for so kind a remembrance of me. Do not forget to make enquiries about the origin, even if only traditionally known, of any varieties of domestic quadrupeds, birds, silkworms, etc. Are there domestic bees? if so hives ought to be brought home. Of all the facts you mention, that of the wild [illegible], when breeding with the domestic, producing offspring somewhat sterile, is the most surprising: surely they must be different species. Most zoologists would absolutely disbelieve such a statement, and consider the result as a proof that they were distinct species. I do not go so far as that, but the case seems highly improbable. Blyth has studied the Indian Ruminantia. I have been much struck about what you say of lowland plants ascending mountains, but the alpine not descending. How I do hope you will get up some mountains in Borneo; how curious the result will be! By the way, I never heard from you what affinity the Maldive flora has, which is cruel, as you tempted me by making me guess. I sometimes groan over your Indian journey, when I think over all your locked up riches. When shall I see a memoir on Insular floras, and on the Pacific? What a grand subject Alpine floras of the world (27/1. Mr. William Botting Hemsley, F.R.S., of the Royal Gardens, Kew, is now engaged on a monograph of the high-level Alpine plants of the world.) would be, as far as known; and then you have never given a coup d'oeil on the similarity and dissimilarity of Arctic and Antarctic floras. Well, thank heavens, when you do come back you will be nolens volens a fixture. I am particularly glad you have been at the Coal; I have often since you went gone on maundering on the subject, and I shall never rest easy in Down churchyard without the problem be solved by some one before I die. Talking of dying makes me tell you that my confounded stomach is much the same; indeed, of late has been rather worse, but for the last year, I think, I have been able to do more work. I have done nothing besides the barnacles, except, indeed, a little theoretical paper on erratic boulders (27/2. "On the Transportal of Erratic Boulders from a Lower to a Higher Level" ("Quart. Journ. Geol. Soc." Volume IV., pages 315-23. 1848). In this paper Darwin favours the view that the transport of boulders was effected by coast-ice. An earlier paper entitled "Notes on the Effects produced by the ancient Glaciers of Caernarvonshire, and on the Boulders transported by floating Ice" ("Phil. Mag." 1842, page 352) is spoken of by Sir Archibald Geikie as standing "almost at the top of the long list of English contributions to the history of the Ice Age" ("Charles Darwin," "Nature" Series, page 23).), and Scientific Geological Instructions for the Admiralty Volume (27/3. "A manual of Scientific Enquiry, prepared for the use of Her Majesty's Navy, and adapted for Travellers in General." Edited by Sir John F.W. Herschel, Bart. Section VI.--Geology--by Charles Darwin. London, 1849. See "Life and Letters," pages 328-9.), which cost me some trouble. This work, which is edited by Sir J. Herschel, is a very good job, inasmuch as the captains of men-of-war will now see that the Admiralty cares for science, and so will favour naturalists on board. As for a man who is not scientific by nature, I do not believe instructions will do him any good; and if he be scientific and good for anything the instructions will be superfluous. I do not know who does the Botany; Owen does the Zoology, and I have sent him an account of my new simple microscope, which I consider perfect, even better than yours by Chevalier. N.B. I have got a 1/8 inch object-glass, and it is grand. I have been getting on well with my beloved Cirripedia, and get more skilful in dissection. I have worked out the nervous system pretty well in several genera, and made out their ears and nostrils (27/4. For the olfactory sacs see Darwin's "Monograph of the Cirripedia," 1851, page 52.), which were quite unknown. I have lately got a bisexual cirripede, the male being microscopically small and parasitic within the sack of the female. I tell you this to boast of my species theory, for the nearest closely allied genus to it is, as usual, hermaphrodite, but I had observed some minute parasites adhering to it, and these parasites I now can show are supplemental males, the male organs in the hermaphrodite being unusually small, though perfect and containing zoosperms: so we have almost a polygamous animal, simple females alone being wanting. I never should have made this out, had not my species theory convinced me, that an hermaphrodite species must pass into a bisexual species by insensibly small stages; and here we have it, for the male organs in the hermaphrodite are beginning to fail, and independent males ready formed. But I can hardly explain what I mean, and you will perhaps wish my barnacles and species theory al Diavolo together. But I don't care what you say, my species theory is all gospel. We have had only one party here: viz., of the Lyells, Forbes, Owen, and Ramsay, and we both missed you and Falconer very much...I know more of your history than you will suppose, for Miss Henslow most good-naturedly sent me a packet of your letters, and she wrote me so nice a little note that it made me quite proud. I have not heard of anything in the scientific line which would interest you. Sir H. De la Beche (27/5. The Presidential Address delivered by De la Beche before the Geological Society in 1848 ("Quart. Journ. Geol. Soc." Volume IV., "Proceedings," page xxi, 1848).) gave a very long and rather dull address; the most interesting part was from Sir J. Ross. Mr. Beete Jukes figured in it very prominently: it really is a very nice quality in Sir Henry, the manner in which he pushes forward his subordinates. Jukes has since read what was considered a very valuable paper. The man, not content with moustaches, now sports an entire beard, and I am sure thinks himself like Jupiter tonans. There was a short time since a not very creditable discussion at a meeting of the Royal Society, where Owen fell foul of Mantell with fury and contempt about belemnites. What wretched doings come from the order of fame; the love of truth alone would never make one man attack another bitterly. My paper is full, so I must wish you with all my heart farewell. Heaven grant that your health may keep good. LETTER 28. TO J.S. HENSLOW. The Lodge, Malvern, May 6th, 1849. Your kind note has been forwarded to me here. You will be surprised to hear that we all--children, servants, and all--have been here for nearly two months. All last autumn and winter my health grew worse and worse: incessant sickness, tremulous hands, and swimming head. I thought I was going the way of all flesh. Having heard of much success in some cases from the cold-water cure, I determined to give up all attempts to do anything and come here and put myself under Dr. Gully. It has answered to a considerable extent: my sickness much checked and considerable strength gained. Dr. G., moreover (and I hear he rarely speaks confidently), tells me he has little doubt but that he can cure me in the course of time--time, however, it will take. I have experienced enough to feel sure that the cold-water cure is a great and powerful agent and upsetter of all constitutional habits. Talking of habits, the cruel wretch has made me leave off snuff--that chief solace of life. We thank you most sincerely for your prompt and early invitation to Hitcham for the British Association for 1850 (28/1. The invitation was probably not for 1850, but for 1851, when the Association met at Ipswich.): if I am made well and strong, most gladly will I accept it; but as I have been hitherto, a drive every day of half a dozen miles would be more than I could stand with attending any of the sections. I intend going to Birmingham (28/2. The Association met at Birmingham in 1849.) if able; indeed, I am bound to attempt it, for I am honoured beyond all measure in being one of the Vice-Presidents. I am uncommonly glad you will be there; I fear, however, we shall not have any such charming trips as Nuneham and Dropmore. (28/3. In a letter to Hooker (October 12th, 1849) Darwin speaks of "that heavenly day at Dropmore." ("Life and Letters," I., page 379.)) We shall stay here till at least June 1st, perhaps till July 1st; and I shall have to go on with the aqueous treatment at home for several more months. One most singular effect of the treatment is that it induces in most people, and eminently in my case, the most complete stagnation of mind. I have ceased to think even of barnacles! I heard some time since from Hooker...How capitally he seems to have succeeded in all his enterprises! You must be very busy now. I happened to be thinking the other day over the Gamlingay trip to the Lilies of the Valley (28/4. The Lily of the Valley (Convallaria majalis) is recorded from Gamlingay by Professor Babington in his "Flora of Cambridgeshire," page 234. (London, 1860.)): ah, those were delightful days when one had no such organ as a stomach, only a mouth and the masticating appurtenances. I am very much surprised at what you say, that men are beginning to work in earnest [at] Botany. What a loss it will be for Natural History that you have ceased to reside all the year in Cambridge! LETTER 29. TO J.F. ROYLE. Down, September 1st [184-?]. I return you with very many thanks your valuable work. I am sure I have not lost any slip or disarranged the loose numbers. I have been interested by looking through the volumes, though I have not found quite so much as I had thought possible about the varieties of the Indian domestic animals and plants, and the attempts at introduction have been too recent for the effects (if any) of climate to have been developed. I have, however, been astonished and delighted at the evidence of the energetic attempts to do good by such numbers of people, and most of them evidently not personally interested in the result. Long may our rule flourish in India. I declare all the labour shown in these transactions is enough by itself to make one proud of one's countrymen... LETTER 30. TO HUGH STRICKLAND. (30/1. The first paragraph of this letter is published in the "Life and Letters," I., page 372, as part of a series of letters to Strickland, beginning at page 365, where a biographical note by Professor Newton is also given. Professor Newton wrote: "In 1841 he brought the subject of Natural History Nomenclature before the British Association, and prepared the code of rules for Zoological Nomenclature, now known by his name--the principles of which are very generally accepted." Mr. Darwin's reasons against appending the describer's name to that of the species are given in "Life and Letters," page 366. The present letter is of interest as giving additional details in regard to Darwin's difficulties.) Down, February 10th [1849]. I have again to thank you cordially for your letter. Your remarks shall fructify to some extent, and I will try to be more faithful to rigid virtue and priority; but as for calling Balanus "Lepas" (which I did not think of) I cannot do it, my pen won't write it--it is impossible. I have great hopes some of my difficulties will disappear, owing to wrong dates in Agassiz and to my having to run several genera into one; for I have as yet gone, in but few cases, to original sources. With respect to adopting my own notions in my Cirripedia book, I should not like to do so without I found others approved, and in some public way; nor indeed is it well adapted, as I can never recognise a species without I have the original specimen, which fortunately I have in many cases in the British Museum. Thus far I mean to adopt my notion, in never putting mihi or Darwin after my own species, and in the anatomical text giving no authors' names at all, as the systematic part will serve for those who want to know the history of the species as far as I can imperfectly work it out. I have had a note from W. Thompson (30/2. Mr. Thompson is described in the preface to the Lepadidae as "the distinguished Natural Historian of Ireland.") this morning, and he tells me Ogleby has some scheme identical almost with mine. I feel pretty sure there is a growing general aversion to the appendage of author's name, except in cases where necessary. Now at this moment I have seen specimens ticketed with a specific name and no reference--such are hopelessly inconvenient; but I declare I would rather (as saving time) have a reference to some second systematic work than to the original author, for I have cases of this which hardly help me at all, for I know not where to look amongst endless periodical foreign papers. On the other hand, one can get hold of most systematic works and so follow up the scent, and a species does not long lie buried exclusively in a paper. I thank you sincerely for your very kind offer of occasionally assisting me with your opinion, and I will not trespass much. I have a case, but [it is one] about which I am almost sure; and so to save you writing, if I conclude rightly, pray do not answer, and I shall understand silence as assent. Olfers in 1814 made Lepas aurita Linn. into the genus Conchoderma; [Oken] in 1815 gave the name Branta to Lepas aurita and vittata, and by so doing he alters essentially Olfers' generic definition. Oken was right (as it turns out), and Lepas aurita and vittata must form together one genus. (30/3. In the "Monograph on the Cirripedia" (Lepadidae) the names used are Conchoderma aurita and virgata.) (I leave out of question a multitude of subsequent synonyms.) Now I suppose I must retain Conchoderma of Olfers. I cannot make out a precise rule in the "British Association Report" for this. When a genus is cut into two I see that the old name is retained for part and altered to it; so I suppose the definition may be enlarged to receive another species--though the cases are somewhat different. I should have had no doubt if Lepas aurita and vittata had been made into two genera, for then when run together the oldest of the two would have been retained. Certainly to put Conchoderma Olfers is not quite correct when applied to the two species, for such was not Olfers' definition and opinion. If I do not hear, I shall retain Conchoderma for the two species... P.S.--Will you by silence give consent to the following? Linnaeus gives no type to his genus Lepas, though L. balanus comes first. Several oldish authors have used Lepas exclusively for the pedunculate division, and the name has been given to the family and compounded in sub-generic names. Now, this shows that old authors attached the name Lepas more particularly to the pedunculate division. Now, if I were to use Lepas for Anatifera (30/4. Anatifera and Anatifa were used as generic names for what Linnaeus and Darwin called Lepas anatifera.) I should get rid of the difficulty of the second edition of Hill and of the difficulty of Anatifera vel Anatifa. Linnaeus's generic description is equally applicable to Anatifera and Balanus, though the latter stands first. Must the mere precedence rigorously outweigh the apparent opinion of many old naturalists? As for using Lepas in place of Balanus, I cannot. Every one will understand what is meant by Lepas Anatifera, so that convenience would be wonderfully thus suited. If I do not hear, I shall understand I have your consent. LETTER 31. J.D. HOOKER TO CHARLES DARWIN. (31/1. In the "Life and Letters," I., page 392, is a letter to Sir J.D. Hooker from Mr. Darwin, to whom the former had dedicated his "Himalayan Journals." Mr. Darwin there wrote: "Your letter, received this morning, has interested me extremely, and I thank you sincerely for telling me your old thoughts and aspirations." The following is the letter referred to, which at our request Sir Joseph has allowed us to publish.) Kew, March 1st, 1854. Now that my book (31/2. "Himalayan Journals," 2 volumes. London, 1854.) has been publicly acknowledged to be of some value, I feel bold to write to you; for, to tell you the truth, I have never been without a misgiving that the dedication might prove a very bad compliment, however kindly I knew you would receive it. The idea of the dedication has been present to me from a very early date: it was formed during the Antarctic voyage, out of love for your own "Journal," and has never deserted me since; nor would it, I think, had I never known more of you than by report and as the author of the said "Naturalist's Journal." Short of the gratification I felt in getting the book out, I know no greater than your kind, hearty acceptation of the dedication; and, had the reviewers gibbeted me, the dedication would alone have given me real pain. I have no wish to assume a stoical indifference to public opinion, for I am well alive to it, and the critics might have irritated me sorely, but they could never have caused me the regret that the association of your name with a bad book of mine would have. You will laugh when I tell you that, my book out, I feel past the meridian of life! But you do not know how from my earliest childhood I nourished and cherished the desire to make a creditable journey in a new country, and write such a respectable account of its natural features as should give me a niche amongst the scientific explorers of the globe I inhabit, and hand my name down as a useful contributor of original matter. A combination of most rare advantages has enabled me to gain as much of my object as contents me, for I never wished to be greatest amongst you, nor did rivalry ever enter my thoughts. No ulterior object has ever been present to me in this pursuit. My ambition is fully gratified by the satisfactory completion of my task, and I am now happy to go on jog-trot at Botany till the end of my days--downhill, in one sense, all the way. I shall never have such another object to work for, nor shall I feel the want of it...As it is, the craving of thirty years is satisfied, and I now look back on life in a way I never could previously. There never was a past hitherto to me. The phantom was always in view; mayhap it is only a "ridiculus mus" after all, but it is big enough for me... (PLATE: T.H. HUXLEY, 1857. Maull & Polyblank photo., Walker & Cockerell ph. sc.) (32/1. The story of Huxley's life has been fully given in the interesting biography edited by Mr. Leonard Huxley. (32/2. "Life and Letters of Thomas Henry Huxley." London 1900.) Readers of this book and of the "Life and Letters of Charles Darwin" gain an insight into the relationship between this pair of friends to which any words of ours can add but little. Darwin realised to the full the essential strength of Mr. Huxley's nature; he knew, as all the world now knows, the delicate sense of honour of his friend, and he was ever inclined to lean on his guidance in practical matters, as on an elder brother. Of Mr. Huxley's dialectical and literary skill he was an enthusiastic admirer, and he never forgot what his theories owed to the fighting powers of his "general agent." (32/3. Ibid., I., page 171.) Huxley's estimate of Darwin is very interesting: he valued him most highly for what was so strikingly characteristic of himself--the love of truth. He spoke of finding in him "something bigger than ordinary humanity--an unequalled simplicity and directness of purpose--a sublime unselfishness." (32/4. Ibid., II., page 94. Huxley is speaking of Gordon's death, and goes on: "Of all the people whom I have met with in my life, he and Darwin are the two in whom I have found," etc.) The same point of view comes out in Huxley's estimate of Darwin's mental power. (32/5. Ibid., II., page 39.) "He had a clear, rapid intelligence, a great memory, a vivid imagination, and what made his greatness was the strict subordination of all these to his love of truth." This, as an analysis of Darwin's mental equipment, seems to us incomplete, though we do not pretend to mend it. We do not think it is possible to dissect and label the complex qualities which go to make up that which we all recognise as genius. But, if we may venture to criticise, we would say that Mr. Huxley's words do not seem to cover that supreme power of seeing and thinking what the rest of the world had overlooked, which was one of Darwin's most striking characteristics. As throwing light on the quality of their friendship, we give below a letter which has already appeared in the "Life and Letters of T.H. Huxley," I., page 366. Mr. L. Huxley gives an account of the breakdown in health which convinced Huxley's friends that rest and relief from anxiety must be found for him. Mr. L. Huxley aptly remarks of the letter, "It is difficult to say whether it does more honour to him who sent it or to him who received it." (32/6. Huxley's "Life," I., page 366. Mr. Darwin left to Mr. Huxley a legacy of 1,000 pounds, "as a slight memorial of my lifelong affection and respect for him.")) LETTER 32. TO T.H. HUXLEY. Down, April 23rd, 1873. My dear Huxley I have been asked by some of your friends (eighteen in number) to inform you that they have placed, through Robarts, Lubbock & Co., the sum of 2,100 pounds to your account at your bankers. We have done this to enable you to get such complete rest as you may require for the re-establishment of your health; and in doing this we are convinced that we act for the public interest, as well as in accordance with our most earnest desires. Let me assure you that we are all your warm personal friends, and that there is not a stranger or mere acquaintance amongst us. If you could have heard what was said, or could have read what was, as I believe, our inmost thoughts, you would know that we all feel towards you, as we should to an honoured and much loved brother. I am sure that you will return this feeling, and will therefore be glad to give us the opportunity of aiding you in some degree, as this will be a happiness to us to the last day of our lives. Let me add that our plan occurred to several of your friends at nearly the same time and quite independently of one another. My dear Huxley, Your affectionate friend, CHARLES DARWIN. LETTER 33. TO T.H. HUXLEY. (33/1. The following letter is one of the earliest of the long series addressed to Mr. Huxley.) Down, April 23rd [1854]. My dear Sir I have got out all the specimens, which I have thought could by any possibility be of any use to you; but I have not looked at them, and know not what state they are in, but should be much pleased if they are of the smallest use to you. I enclose a catalogue of habitats: I thought my notes would have turned out of more use. I have copied out such few points as perhaps would not be apparent in preserved specimens. The bottle shall go to Mr. Gray on Thursday next by our weekly carrier. I am very much obliged for your paper on the Mollusca (33/2. The paper of Huxley's is "On the Morphology of the Cephalous Mollusca, etc." ("Phil. Trans. R. Soc." Volume 143, Part I., 1853, page 29.)); I have read it all with much interest: but it would be ridiculous in me to make any remarks on a subject on which I am so utterly ignorant; but I can see its high importance. The discovery of the type or "idea" (33/3. Huxley defines his use of the word "archetype" at page 50: "All that I mean is the conception of a form embodying the most general propositions that can be affirmed respecting the Cephalous Mollusca, standing in the same relation to them as the diagram to a geometrical theorem, and like it, at once, imaginary and true.") (in your sense, for I detest the word as used by Owen, Agassiz & Co.) of each great class, I cannot doubt, is one of the very highest ends of Natural History; and certainly most interesting to the worker-out. Several of your remarks have interested me: I am, however, surprised at what you say versus "anamorphism" (33/4. The passage referred to is at page 63: "If, however, all Cephalous Mollusks...be only modifications by excess or defect of the parts of a definite archetype, then, I think, it follows as a necessary consequence, that no anamorphism takes place in this group. There is no progression from a lower to a higher type, but merely a more or less complete evolution of one type." Huxley seems to use the term anamorphism in a sense differing from that of some writers. Thus in Jourdan's "Dictionnaire des Termes Usites dans les Sciences Naturelles," 1834, it is defined as the production of an atypical form either by arrest or excess of development.), I should have thought that the archetype in imagination was always in some degree embryonic, and therefore capable [of] and generally undergoing further development. Is it not an extraordinary fact, the great difference in position of the heart in different species of Cleodora? (33/5. A genus of Pteropods.) I am a believer that when any part, usually constant, differs considerably in different allied species that it will be found in some degree variable within the limits of the same species. Thus, I should expect that if great numbers of specimens of some of the species of Cleodora had been examined with this object in view, the position of the heart in some of the species would have been found variable. Can you aid me with any analogous facts? I am very much pleased to hear that you have not given up the idea of noticing my cirripedial volume. All that I have seen since confirms everything of any importance stated in that volume--more especially I have been able rigorously to confirm in an anomalous species, by the clearest evidence, that the actual cellular contents of the ovarian tubes, by the gland-like action of a modified portion of the continuous tube, passes into the cementing stuff: in fact cirripedes make glue out of their own unformed eggs! (33/6. On Darwin's mistake in this point see "Life and Letters," III., page 2.) Pray believe me, Yours sincerely, C. DARWIN. I told the above case to Milne Edwards, and I saw he did not place the smallest belief in it. LETTER 34. TO T.H. HUXLEY. Down, September 2nd, [1854]. My second volume on the everlasting barnacles is at last published (34/1. "A Monograph of the Sub-class Cirripedia. II. The Balanidae, the Verrucidae." Ray Society, 1854.), and I will do myself the pleasure of sending you a copy to Jermyn Street next Thursday, as I have to send another book then to Mr. Baily. And now I want to ask you a favour--namely, to answer me two questions. As you are so perfectly familiar with the doings, etc., of all Continental naturalists, I want you to tell me a few names of those whom you think would care for my volume. I do not mean in the light of puffing my book, but I want not to send copies to those who from other studies, age, etc., would view it as waste paper. From assistance rendered me, I consider myself bound to send copies to: (1) Bosquet of Maestricht, (2) Milne Edwards, (3) Dana, (4) Agassiz, (5) Muller, (6) W. Dunker of Hesse Cassel. Now I have five or six other copies to distribute, and will you be so very kind as to help me? I had thought of Von Siebold, Loven, d'Orbigny, Kolliker, Sars, Kroyer, etc., but I know hardly anything about any of them. My second question, it is merely a chance whether you can answer,--it is whether I can send these books or any of them (in some cases accompanied by specimens), through the Royal Society: I have some vague idea of having heard that the Royal Society did sometimes thus assist members. I have just been reading your review of the "Vestiges" (34/2. In his chapter on the "Reception of the Origin of Species" ("Life and Letters," II., pages 188-9), Mr. Huxley wrote: "and the only review I ever have qualms of conscience about, on the ground of needless savagery, is one I wrote on the 'Vestiges.'" The article is in the "British and Foreign Medico-chirurgical Review," XIII., 1854, page 425. The "great man" referred to below is Owen: see Huxley's review, page 439, and Huxley's "Life." I., page 94.), and the way you handle a great Professor is really exquisite and inimitable. I have been extremely interested in other parts, and to my mind it is incomparably the best review I have read on the "Vestiges"; but I cannot think but that you are rather hard on the poor author. I must think that such a book, if it does no other good, spreads the taste for Natural Science. But I am perhaps no fair judge, for I am almost as unorthodox about species as the "Vestiges" itself, though I hope not quite so unphilosophical. How capitally you analyse his notion about law. I do not know when I have read a review which interested me so much. By Heavens, how the blood must have gushed into the capillaries when a certain great man (whom with all his faults I cannot help liking) read it! I am rather sorry you do not think more of Agassiz's embryological stages (34/3. See "Origin," Edition VI., page 310: also Letter 40, Note.), for though I saw how exceedingly weak the evidence was, I was led to hope in its truth. LETTER 35. TO J.D. HOOKER. Down [1854]. With respect to "highness" and "lowness," my ideas are only eclectic and not very clear. It appears to me that an unavoidable wish to compare all animals with men, as supreme, causes some confusion; and I think that nothing besides some such vague comparison is intended, or perhaps is even possible, when the question is whether two kingdoms such as the Articulata or Mollusca are the highest. Within the same kingdom I am inclined to think that "highest" usually means that form which has undergone most "morphological differentiation" from the common embryo or archetype of the class; but then every now and then one is bothered (as Milne Edwards has remarked) by "retrograde development," i.e., the mature animal having fewer and less important organs than its own embryo. The specialisation of parts to different functions, or "the division of physiological labour" (35/1. A slip of the pen for "physiological division of labour.") of Milne Edwards exactly agrees (and to my mind is the best definition, when it can be applied) with what you state is your idea in regard to plants. I do not think zoologists agree in any definite ideas on this subject; and my ideas are not clearer than those of my brethren. LETTER 36. TO J.D. HOOKER. Down, July 2nd [1854]. I have had the house full of visitors, and when I talk I can do absolutely nothing else; and since then I have been poorly enough, otherwise I should have answered your letter long before this, for I enjoy extremely discussing such points as those in your last note. But what a villain you are to heap gratuitous insults on my ELASTIC theory: you might as well call the virtue of a lady elastic, as the virtue of a theory accommodating in its favours. Whatever you may say, I feel that my theory does give me some advantages in discussing these points. But to business: I keep my notes in such a way, viz., in bulk, that I cannot possibly lay my hand on any reference; nor as far as the vegetable kingdom is concerned do I distinctly remember having read any discussion on general highness or lowness, excepting Schleiden (I fancy) on Compositae being highest. Ad. de Jussieu (36/1. "Monographie de la Famille des Malpighiacees," by Adrien de Jussieu, "Arch. du Museum." Volume III., page 1, 1843.), in "Arch. du Museum," Tome 3, discusses the value of characters of degraded flowers in the Malpighiaceae, but I doubt whether this at all concerns you. Mirbel somewhere has discussed some such question. Plants lie under an enormous disadvantage in respect to such discussions in not passing through larval stages. I do not know whether you can distinguish a plant low from non-development from one low from degradation, which theoretically, at least, are very distinct. I must agree with Forbes that a mollusc may be higher than one articulate animal and lower than another; if one was asked which was highest as a whole, the Molluscan or Articulate Kingdom, I should look to and compare the highest in each, and not compare their archetypes (supposing them to be known, which they are not.) But there are, in my opinion, more difficult cases than any we have alluded to, viz., that of fish--but my ideas are not clear enough, and I do not suppose you would care to hear what I obscurely think on this subject. As far as my elastic theory goes, all I care about is that very ancient organisms (when different from existing) should tend to resemble the larval or embryological stages of the existing. I am glad to hear what you say about parallelism: I am an utter disbeliever of any parallelism more than mere accident. It is very strange, but I think Forbes is often rather fanciful; his "Polarity" (36/2. See Letter 41, Note.) makes me sick--it is like "magnetism" turning a table. If I can think of any one likely to take your "Illustrations" (36/3. "Illustrations of Himalayan Plants from Drawings made by J.F. Cathcart." Folio, 1855.), I will send the advertisement. If you want to make up some definite number so as to go to press, I will put my name down with PLEASURE (and I hope and believe that you will trust me in saying so), though I should not in the course of nature subscribe to any horticultural work:--act for me. LETTER 37. TO J.D. HOOKER. Down, [May] 29th, 1854. I am really truly sorry to hear about your [health]. I entreat you to write down your own case,--symptoms, and habits of life,--and then consider your case as that of a stranger; and I put it to you, whether common sense would not order you to take more regular exercise and work your brain less. (N.B. Take a cold bath and walk before breakfast.) I am certain in the long run you would not lose time. Till you have a thoroughly bad stomach, you will not know the really great evil of it, morally, physically, and every way. Do reflect and act resolutely. Remember your troubled heart-action formerly plainly told how your constitution was tried. But I will say no more--excepting that a man is mad to risk health, on which everything, including his children's inherited health, depends. Do not hate me for this lecture. Really I am not surprised at your having some headache after Thursday evening, for it must have been no small exertion making an abstract of all that was said after dinner. Your being so engaged was a bore, for there were several things that I should have liked to have talked over with you. It was certainly a first-rate dinner, and I enjoyed it extremely, far more than I expected. Very far from disagreeing with me, my London visits have just lately taken to suit my stomach admirably; I begin to think that dissipation, high-living, with lots of claret, is what I want, and what I had during the last visit. We are going to act on this same principle, and in a very profligate manner have just taken a pair of season-tickets to see the Queen open the Crystal Palace. (37/1. Queen Victoria opened the Crystal Palace at Sydenham on June 10th, 1854.) How I wish there was any chance of your being there! The last grand thing we were at together answered, I am sure, very well, and that was the Duke's funeral. Have you seen Forbes' introductory lecture (37/2. Edward Forbes was appointed to a Professorship at Edinburgh in May, 1854.) in the "Scotsman" (lent me by Horner)? it is really ADMIRABLY done, though without anything, perhaps, very original, which could hardly be expected: it has given me even a higher opinion than I before had, of the variety and polish of his intellect. It is, indeed, an irreparable loss to London natural history society. I wish, however, he would not praise so much that old brown dry stick Jameson. Altogether, to my taste, it is much the best introductory lecture I have ever read. I hear his anniversary address is very good. Adios, my dear Hooker; do be wise and good, and be careful of your stomach, within which, as I know full well, lie intellect, conscience, temper, and the affections. LETTER 38. TO J.D. HOOKER. Down, December 2nd [1854]. You are a pretty fellow to talk of funking the returning thanks at the dinner for the medal. (38/1. The Royal medal was given to Sir Joseph in 1854.) I heard that it was decidedly the best speech of the evening, given "with perfect fluency, distinctness, and command of language," and that you showed great self-possession: was the latter the proverbially desperate courage of a coward? But you are a pretty fellow to be so desperately afraid and then to make the crack speech. Many such an ordeal may you have to go through! I do not know whether Sir William [Hooker] would be contented with Lord Rosse's (38/2. President of the Royal Society 1848-54.) speech on giving you the medal; but I am very much pleased with it, and really the roll of what you have done was, I think, splendid. What a great pity he half spoiled it by not having taken the trouble just to read it over first. Poor Hofmann (38/3. August Wilhelm Hofmann, the other medallist of 1854.) came off in this respect even worse. It is really almost arrogant insolence against every one not an astronomer. The next morning I was at a very pleasant breakfast party at Sir R. Inglis's. (38/4. Sir Robert Inglis, President of the British Association in 1847. Apparently Darwin was present at the afternoon meeting, but not at the dinner.) I have received, with very many thanks, the aberrant genera; but I have not had time to consider them, nor your remarks on Australian botanical geography. LETTER 39. TO T.H. HUXLEY. (39/1. The following letter shows Darwin's interest in the adjudication of the Royal medals. The year 1855 was the last during which he served on the Council of the Society. He had previously served in 1849-50.) Down, March 31st, 1855. I have thought and enquired much about Westwood, and I really think he amply deserves the gold medal. But should you think of some one with higher claim I am quite ready to give up. Indeed, I suppose without I get some one to second it, I cannot propose him. Will you be so kind as to read the enclosed, and return it to me? Should I send it to Bell? That is, without you demur or convince me. I had thought of Hancock, a higher class of labourer; but, as far as I can weigh, he has not, as yet, done so much as Westwood. I may state that I read the whole "Classification" (39/2. Possibly Westwood's "Introduction to the Modern Classification of Insects" (1839).) before I was on the Council, and ever thought on the subject of medals. I fear my remarks are rather lengthy, but to do him justice I could not well shorten them. Pray tell me frankly whether the enclosed is the right sort of thing, for though I was once on the Council of the Royal, I never attended any meetings, owing to bad health. With respect to the Copley medal (39/3. The Copley Medal was given to Lyell in 1858.), I have a strong feeling that Lyell has a high claim, but as he has had the Royal Medal I presume that it would be thought objectionable to propose him; and as I intend (you not objecting and converting me) to propose W. for the Royal, it would, of course, appear intolerably presumptuous to propose for the Copley also. LETTER 40. TO T.H. HUXLEY. Down, June 10th, 1855. Shall you attend the Council of the Royal Society on Thursday next? I have not been very well of late, and I doubt whether I can attend; and if I could do anything (pray conceal the scandalous fact), I want to go to the Crystal Palace to meet the Horners, Lyells, and a party. So I want to know whether you will speak for me most strongly for Barrande. You know better than I do his admirable labours on the development of trilobites, and his most important work on his Lower or Primordial Zone. I enclose an old note of Lyell's to show what he thinks. With respect to Dana, whom I also proposed, you know well his merits. I can speak most highly of his classificatory work on crustacea and his Geographical Distribution. His Volcanic Geology is admirable, and he has done much good work on coral reefs. If you attend, do not answer this; but if you cannot be at the Council, please inform me, and I suppose I must, if I can, attend. Thank you for your abstract of your lecture at the Royal Institution, which interested me much, and rather grieved me, for I had hoped things had been in a slight degree otherwise. (40/1. "On certain Zoological Arguments commonly adduced in favour of the hypothesis of the Progressive Development of Animal Life," Discourse, Friday, April 20, 1855: "Proceedings R.I." (1855). Published also in "Huxley's Scientific Memoirs." The lecturer dwelt chiefly on the argument of Agassiz, which he summarises as follows: "Homocercal fishes have in their embryonic state heterocercal tails; therefore heterocercality is, so far, a mark of an embryonic state as compared with homocercality, and the earlier heterocercal fish are embryonic as compared with the later homocercal." He shows that facts do not support this view, and concludes generally "that there is no real parallel between the successive forms assumed in the development of the life of the individual at present and those which have appeared at different epochs in the past.") I heard some time ago that before long I might congratulate you on becoming a married man. (40/2. Mr. Huxley was married July 21st, 1855.) From my own experience of some fifteen years, I am very sure that there is nothing in this wide world which more deserves congratulation, and most sincerely and heartily do I congratulate you, and wish you many years of as much happiness as this world can afford. LETTER 41. TO J.D. HOOKER. (41/1. The following letter illustrates Darwin's work on aberrant genera. In the "Origin," Edition I., page 429, he wrote: "The more aberrant any form is, the greater must be the number of connecting forms which, on my theory, have been exterminated and utterly lost. And we have some evidence of aberrant forms having suffered severely from extinction, for they are generally represented by extremely few species; and such species as do occur are generally very distinct from each other, which again implies extinction.") Down, November 15th [1855?]. In Schoenherr's Catalogue of Curculionidae (41/2. "Genera et Species Curculionidum." (C.J. Schoenherr: Paris, 1833-38.)), the 6,717 species are on an average 10.17 to a genus. Waterhouse (who knows the group well, and who has published on fewness of species in aberrant genera) has given me a list of 62 aberrant genera, and these have on an average 7.6 species; and if one single genus be removed (and which I cannot yet believe ought to be considered aberrant), then the 61 aberrant genera would have only 4.91 species on an average. I tested these results in another way. I found in Schoenherr 9 families, including only 11 genera, and these genera (9 of which were in Waterhouse's list) I found included only 3.36 species on an average. This last result led me to Lindley's "Vegetable Kingdom," in which I found (excluding thallogens and acrogens) that the genera include each 10.46 species (how near by chance to the Curculionidae), and I find 21 orders including single genera, and these 21 genera have on average 7.95 species; but if Lindley is right that Erythroxylon (with its 75 species) ought to be amongst the Malpighiads, then the average would be only 4.6 per genus. But here comes, as it appears to me, an odd thing (I hope I shall not quite weary you out). There are 29 other orders, each with 2 genera, and these 58 genera have on an average 15.07 species: this great number being owing to the 10 genera in the Smilaceae, Salicaceae (with 220 species), Begoniaceae, Balsaminaceae, Grossulariaceae, without which the remaining 48 genera have on an average only 5.91 species. This case of the orders with only 2 genera, the genera notwithstanding having 15.07 species each, seems to me very perplexing and upsets, almost, the conclusion deducible from the orders with single genera. I have gone higher, and tested the alliances with 1, 2, and 3 orders; and in these cases I find both the genera few in each alliance, and the species, less than the average of the whole kingdom, in each genus. All this has amused me, but I daresay you will have a good sneer at me, and tell me to stick to my barnacles. By the way, you agree with me that sometimes one gets despondent--for instance, when theory and facts will not harmonise; but what appears to me even worse, and makes me despair, is, when I see from the same great class of facts, men like Barrande deduce conclusions, such as his "Colonies" (41/3. Lyell briefly refers to Barrande's Bohemian work in a letter (August 31st, 1856) to Fleming ("Life of Sir Charles Lyell," II., page 225): "He explained to me on the spot his remarkable discovery of a 'colony' of Upper Silurian fossils, 3,400 feet deep, in the midst of the Lower Silurian group. This has made a great noise, but I think I can explain away the supposed anomaly by, etc." (See Letter 40, Note.) and his agreement with E. de Beaumont's lines of Elevation, or such men as Forbes with his Polarity (41/4. Edward Forbes "On the Manifestation of Polarity in the Distribution of Organised Beings in Time" ("Edinburgh New Phil. Journal," Volume LVII., 1854, page 332). The author points out that "the maximum development of generic types during the Palaeozoic period was during its earlier epochs; that during the Neozoic period towards its later periods." Thus the two periods of activity are conceived to be at the two opposite poles of a sphere which in some way represents for him the system of Nature.); I have not a doubt that before many months are over I shall be longing for the most dishonest species as being more honest than the honestest theories. One remark more. If you feel any interest, or can get any one else to feel any interest on the aberrant genera question, I should think the most interesting way would be to take aberrant genera in any great natural family, and test the average number of species to the genera in that family. How I wish we lived near each other! I should so like a talk with you on geographical distribution, taken in its greatest features. I have been trying from land productions to take a very general view of the world, and I should so like to see how far it agrees with plants. LETTER 42. TO MRS. LYELL. (42/1. Mrs. Lyell is a daughter of the late Mr. Leonard Horner, and widow of Lieut.-Col. Lyell, a brother of Sir Charles.) Down, January 26th [1856]. I shall be very glad to be of any sort of use to you in regard to the beetles. But first let me thank you for your kind note and offer of specimens to my children. My boys are all butterfly hunters; and all young and ardent lepidopterists despise, from the bottom of their souls, coleopterists. The simplest plan for your end and for the good of entomology, I should think, would be to offer the collection to Dr. J.E. Gray for the British Museum on condition that a perfect set was made out for you. If the collection was at all valuable, I should think he would be very glad to have this done. Whether any third set would be worth making out would depend on the value of the collection. I do not suppose that you expect the insects to be named, for that would be a most serious labour. If you do not approve of this scheme, I should think it very likely that Mr. Waterhouse would think it worth his while to set a series for you, retaining duplicates for himself; but I say this only on a venture. You might trust Mr. Waterhouse implicitly, which I fear, as [illegible] goes, is more than can be said for all entomologists. I presume, if you thought of either scheme, Sir Charles Lyell could easily see the gentlemen and arrange it; but, if not, I could do so when next I come to town, which, however, will not be for three or four weeks. With respect to giving your children a taste for Natural History, I will venture one remark--viz., that giving them specimens in my opinion would tend to destroy such taste. Youngsters must be themselves collectors to acquire a taste; and if I had a collection of English lepidoptera, I would be systematically most miserly, and not give my boys half a dozen butterflies in the year. Your eldest has the brow of an observer, if there be the least truth in phrenology. We are all better, but we have been of late a poor household. LETTER 43. TO J.D. HOOKER. Down [1855]. I should have less scruple in troubling you if I had any confidence what my work would turn out. Sometimes I think it will be good, at other times I really feel as much ashamed of myself as the author of the "Vestiges" ought to be of himself. I know well that your kindness and friendship would make you do a great deal for me, but that is no reason that I should be unreasonable. I cannot and ought not to forget that all your time is employed in work certain to be valuable. It is superfluous in me to say that I enjoy exceedingly writing to you, and that your answers are of the greatest possible service to me. I return with many thanks the proof on Aquilegia (43/1. This seems to refer to the discussion on the genus Aquilegia in Hooker and Thomson's "Flora Indica," 1855, Volume I., Systematic Part, page 44. The authors' conclusion is that "all the European and many of the Siberian forms generally recognised belong to one very variable species." With regard to cirripedes, Mr. Darwin spoke of "certain just perceptible differences which blend together and constitute varieties and not species" ("Life and Letters," I., page 379).): it has interested me much. It is exactly like my barnacles; but for my particular purpose, most unfortunately, both Kolreuter and Gartner have worked chiefly on A. vulgaris and canadensis and atro-purpurea, and these are just the species that you seem not to have studied. N.B. Why do you not let me buy the Indian Flora? You are too magnificent. Now for a short ride on my chief (at present) hobbyhorse, viz. aberrant genera. What you say under your remarks on Lepidodendron seems just the case that I want, to give some sort of evidence of what we both believe in, viz. how groups came to be anomalous or aberrant; and I think some sort of proof is required, for I do not believe very many naturalists would at all admit our view. Thank you for the caution on large anomalous genera first catching attention. I do not quite agree with your "grave objection to the whole process," which is "that if you multiply the anomalous species by 100, and divide the normal by the same, you will then reverse the names..." For, to take an example, Ornithorhynchus and Echidna would not be less aberrant if each had a dozen (I do not say 100, because we have no such cases in the animal kingdom) species instead of one. What would really make these two genera less anomalous would be the creation of many genera and sub-families round and radiating from them on all sides. Thus if Australia were destroyed, Didelphys in S. America would be wonderfully anomalous (this is your case with Proteaceae), whereas now there are so many genera and little sub-families of Marsupiata that the group cannot be called aberrant or anomalous. Sagitta (and the earwig) is one of the most anomalous animals in the world, and not a bit the less because there are a dozen species. Now, my point (which, I think is a slightly new point of view) is, if it is extinction which has made the genus anomalous, as a general rule the same causes of extinction would allow the existence of only a few species in such genera. Whenever we meet (which will be on the 23rd [at the] Club) I shall much like to hear whether this strikes you as sound. I feel all the time on the borders of a circle of truism. Of course I could not think of such a request, but you might possibly:--if Bentham does not think the whole subject rubbish, ask him some time to pick out the dozen most anomalous genera in the Leguminosae, or any great order of which there is a monograph by which I could calculate the ordinary percentage of species to genera. I am the more anxious, as the more I enquire, the fewer are the cases in which it can be done. It cannot be done in birds, or, I fear, in mammifers. I doubt much whether in any other class of insects [other than Curculionidae]. I saw your nice notice of poor Forbes in the "Gardeners' Chronicle," and I see in the "Athenaeum" a notice of meeting on last Saturday of his friends. Of course I shall wish to subscribe as soon as possible to any memorial... I have just been testing practically what disuse does in reducing parts. I have made [skeletons] of wild and tame duck (oh the smell of well-boiled, high duck!), and I find the tame duck ought, according to scale of wild prototype, to have its two wings 360 grains in weight; but it has only 317, or 43 grains too little, or 1/7 of [its] own two wings too little in weight. This seems rather interesting to me. (43/2. On the conclusions drawn from these researches, see Mr. Platt Ball, "The Effects of Use and Disuse" (Nature Series), 1890, page 55. With regard to his pigeons, Darwin wrote, in November 1855: "I love them to that extent that I cannot bear to kill and skeletonise them.") P.S.--I do not know whether you will think this worth reading over. I have worked it out since writing my letter, and tabulate the whole. 21 orders with 1 genus, having 7.95 species (or 4.6?). 29 orders with 2 genera, having 15.05 species on an average. 23 orders each with 3 genera, and these genera include on an average 8.2 species. 20 orders each with 4 genera, and these genera include on an average 12.2 species. 27 orders each with above 50 genera (altogether 4716 genera), and these genera on an average have 9.97 species. From this I conclude, whether there be many or few genera in an order, the number of species in a genus is not much affected; but perhaps when [there is] only one genus in an order it will be affected, and this will depend whether the [genus] Erythroxylon be made a family of. LETTER 44. TO J.D. HOOKER. Down, April 8th [1856]. I have been particularly glad to get your splendid eloge of Lindley. His name had been lately passing through my head, and I had hoped that Miers would have proposed him for the Royal medal. I most entirely agree that the Copley (44/1. The late Professor Lindley never attained the honour of the Copley medal. The Royal medal was awarded to him in 1857.) is more appropriate, and I daresay he would not have valued the Royal. From skimming through many botanical books, and from often consulting the "Vegetable Kingdom," I had (ignorant as I am) formed the highest opinion of his claims as a botanist. If Sharpey will stick up strong for him, we should have some chance; but the natural sciences are but feebly represented in the Council. Sir P. Egerton, I daresay, would be strong for him. You know Bell is out. Now, my only doubt is, and I hope that you will consider this, that the natural sciences being weak on the Council, and (I fancy) the most powerful man in the Council, Col. S[abine], being strong against Lindley, whether we should have any chance of succeeding. It would be so easy to name some eminent man whose name would be well-known to all the physicists. Would Lindley hear of and dislike being proposed for the Copley and not succeeding? Would it not be better on this view to propose him for the Royal? Do think of this. Moreover, if Lindley is not proposed for the Royal, I fear both Royal medals would go [to] physicists; for I, for one, should not like to propose another zoologist, though Hancock would be a very good man, and I fancy there would be a feeling against medals to two botanists. But for whatever Lindley is proposed, I will do my best. We will talk this over here. LETTER 45. TO J.D. HOOKER. Down, May 9th [1856]. ...With respect to Huxley, I was on the point of speaking to Crawford and Strezlecki (who will be on Committee of the Athenaeum) when I bethought me of how Owen would look and what he would say. Cannot you fancy him, with slow and gentle voice, asking "Will Mr. Crawford tell me what Mr. Huxley has done, deserving this honour; I only know that he differs from, and disputes the authority of Cuvier, Ehrenberg, and Agassiz as of no weight at all." And when I began to tell Mr. Crawford what to say, I was puzzled, and could refer him only to some excellent papers in the "Phil. Trans." for which the medal had been awarded. But I doubt, with an opposing faction, whether this would be considered enough, for I believe real scientific merit is not thought enough, without the person is generally well known. Now I want to hear what you deliberately think on this head: it would be bad to get him proposed and then rejected; and Owen is very powerful. LETTER 46. TO J.D. HOOKER. Down [1856]. I have got the Lectures, and have read them. (46/1. The reference is presumably to the Royal Institution Lectures given in 1854-56. Those which we have seen--namely, those reprinted in the "Scientific Memoirs," Volume I.--"On the Common Plan of Animal Form," page 281; "On certain Zoological Arguments, etc." page 300; "On Natural History as Knowledge, Discipline, and Power," page 305, do not seem to us to contain anything likely to offend; but Falconer's attack in the "Ann. and Mag. of Nat. Hist." June 1856, on the last-named lecture, shows strong feeling. A reply by Mr. Huxley appeared in the July number of the same Journal. The most heretical discussion from a modern standpoint is at page 311, where he asks how it is conceivable that the bright colours of butterflies and shells or the elegant forms of Foraminifera can possibly be of service to their possessors; and it is this which especially struck Darwin, judging by the pencil notes on his copy of the Lecture.) Though I believe, as far as my knowledge goes, that Huxley is right, yet I think his tone very much too vehement, and I have ventured to say so in a note to Huxley. I had not thought of these lectures in relation to the Athenaeum (46/2. Mr. Huxley was in 1858 elected to the Athenaeum Club under Rule 2, which provides for the annual election of "a certain number of persons of distinguished eminence in science, literature, or the arts, or for public services."), but I am inclined quite to agree with you, and that we had better pause before anything is said...(N.B. I found Falconer very indignant at the manner in which Huxley treated Cuvier in his Royal Institution lectures; and I have gently told Huxley so.) I think we had better do nothing: to try in earnest to get a great naturalist into the Athenaeum and fail, is far worse than doing nothing. How strange, funny, and disgraceful that nearly all (Faraday and Sir J. Herschel at least exceptions) our great men are in quarrels in couplets; it never struck me before... LETTER 47. C. LYELL TO CHARLES DARWIN. (47/1. In the "Life and Letters," II., page 72, is given a letter (June 16th, 1856) to Lyell, in which Darwin exhales his indignation over the "extensionists" who created continents ad libitum to suit the convenience of their theories. On page 74 a fuller statement of his views is given in a letter dated June 25th. We have not seen Lyell's reply to this, but his reply to Darwin's letter of June 16th is extant, and is here printed for the first time.) 53, Harley Street, London, June 17th, 1856. I wonder you did not also mention D. Sharpe's paper (47/2. "On the Last Elevation of the Alps, etc." ("Quart. Journ. Geol. Soc." Volume XII., 1856, page 102.), just published, by which the Alps were submerged as far as 9,000 feet of their present elevation above the sea in the Glacial period and then since uplifted again. Without admitting this, you would probably convey the alpine boulders to the Jura by marine currents, and if so, make the Alps and Jura islands in the glacial sea. And would not the Glacial theory, as now very generally understood, immerse as much of Europe as I did in my original map of Europe, when I simply expressed all the area which at some time or other had been under water since the commencement of the Eocene period? I almost suspect the glacial submergence would exceed it. But would not this be a measure of the movement in every other area, northern (arctic), antarctic, or tropical, during an equal period--oceanic or continental? For the conversion of sea into land would always equal the turning of much land into sea. But all this would be done in a fraction of the Pliocene period; the Glacial shells are barely 1 per cent. extinct species. Multiply this by the older Pliocene and Miocene epochs. You also forget an author who, by means of atolls, contrived to submerge archipelagoes (or continents?), the mountains of which must originally have differed from each other in height 8,000 (or 10,000?) feet, so that they all just rose to the surface at one level, or their sites are marked by buoys of coral. I could never feel sure whether he meant this tremendous catastrophe, all brought about by what Sedgwick called "Lyell's niggling operations," to have been effected during the era of existing species of corals. Perhaps you can tell me, for I am really curious to know...(47/3. The author referred to is of course Darwin.) Now, although there is nothing in my works to warrant the building up of continents in the Atlantic and Pacific even since the Eocene period, yet, as some of the rocks in the central Alps are in part Eocene, I begin to think that all continents and oceans may be chiefly, if not all, post-Eocene, and Dana's "Atlantic Ocean" of the Lower Silurian is childish (see the Anniversary Address, 1856). (47/4. Probably Dana's Anniversary Address to the "American Association for the Advancement of Science," published in the "Proceedings" 1856.) But how far you are at liberty to call up continents from "the vasty deep" as often as you want to convey a Helix from the United States to Europe in Miocene or Pliocene periods is a question; for the ocean is getting deeper of late, and Haughton says the mean depth is eleven miles! by his late paper on tides. (47/5. "On the Depth of the Sea deducible from Tidal Observations" ("Proc. Irish Acad." Volume VI., page 354, 1853-54).) I shall be surprised if this turns out true by soundings. I thought your mind was expanding so much in regard to time that you would have been going ahead in regard to the possibility of mountain-chains being created in a fraction of the period required to convert a swan into a goose, or vice versa. Nine feet did the Rimutaka chain of New Zealand gain in height in January, 1855, and a great earthquake has occurred in New Zealand every seven years for half a century nearly. The "Washingtonia" (Californian conifer) (47/6. Washingtonia, or Wellingtonia, better known as Sequoia. Asa Gray, writing in 1872, states his belief that "no Sequoia now alive can sensibly antedate the Christian era" ("Scientific Papers," II., page 144).) lately exhibited was four thousand years old, so that one individual might see a chain of hills rise, and rise with it, much [more] a species--and those islands which J. Hooker describes as covered with New Zealand plants three hundred (?) miles to the N.E. (?) of New Zealand may have been separated from the mainland two or three or four generations of Washingtonia ago. If the identity of the land-shells of all the hundreds of British Isles be owing to their having been united since the Glacial period, and the discordance, almost total, of the shells of Porto Santo and Madeira be owing to their having been separated [during] all the newer and possibly older Pliocene periods, then it gives us a conception of time which will aid you much in your conversion of species, if immensity of time will do all you require; for the Glacial period is thus shown, as we might have anticipated, to be contemptible in duration or in distance from us, as compared to the older Pliocene, let alone the Miocene, when our contemporary species were, though in a minority, already beginning to flourish. The littoral shells, according to MacAndrew, imply that Madeira and the Canaries were once joined to the mainland of Europe or Africa, but that those isles were disjoined so long ago that most of the species came in since. In short, the marine shells tell the same story as the land shells. Why do the plants of Porto Santo and Madeira agree so nearly? And why do the shells which are the same as European or African species remain quite unaltered, like the Crag species, which returned unchanged to the British seas after being expelled from them by glacial cold, when two millions (?) of years had elapsed, and after such migration to milder seas? Be so good as to explain all this in your next letter. LETTER 48. TO J.D. HOOKER. Down, July 5th [1856]. I write this morning in great tribulation about Tristan d'Acunha. (48/1. See "Flora Antarctica," page 216. Though Tristan d'Acunha is "only 1,000 miles distant from the Cape of Good Hope, and 3,000 from the Strait of Magalhaens, the botany of this island is far more intimately allied to that of Fuegia than Africa.") The more I reflect on your Antarctic flora the more I am astounded. You give all the facts so clearly and fully, that it is impossible to help speculating on the subject; but it drives me to despair, for I cannot gulp down your continent; and not being able to do so gives, in my eyes, the multiple creationists an awful triumph. It is a wondrous case, and how strange that A. De Candolle should have ignored it; which he certainly has, as it seems to me. I wrote Lyell a long geological letter (48/2. "Life and Letters," II., page 74.) about continents, and I have had a very long and interesting answer; but I cannot in the least gather his opinion about all your continental extensionists; and I have written again beseeching a verdict. (48/3. In the tenth edition of the "Principles," 1872, Lyell added a chapter (Chapter XLI., page 406) on insular floras and faunas in relation to the origin of species; he here (page 410) gives his reasons against Forbes as an extensionist.) I asked him to send to you my letter, for as it was well copied it would not be troublesome to read; but whether worth reading I really do not know; I have given in it the reasons which make me strongly opposed to continental extensions. I was very glad to get your note some days ago: I wish you would think it worth while, as you intend to have the Laburnum case translated, to write to "Wien" (that unknown place) (48/4. There is a tradition that Darwin once asked Hooker where "this place Wien is, where they publish so many books."), and find out how the Laburnum has been behaving: it really ought to be known. The Entada is a beast. (48/5. The large seeds of Entada scandens are occasionally floated across the Atlantic and cast on the shores of Europe.); I have never differed from you about the growth of a plant in a new island being a FAR harder trial than transportal, though certainly that seems hard enough. Indeed I suspect I go even further than you in this respect; but it is too long a story. Thank you for the Aristolochia and Viscum cases: what species were they? I ask, because oddly these two very genera I have seen advanced as instances (I forget at present by whom, but by good men) in which the agency of insects was absolutely necessary for impregnation. In our British dioecious Viscum I suppose it must be necessary. Was there anything to show that the stigma was ready for pollen in these two cases? for it seems that there are many cases in which pollen is shed long before the stigma is ready. As in our Viscum, insects carry, sufficiently regularly for impregnation, pollen from flower to flower, I should think that there must be occasional crosses even in an hermaphrodite Viscum. I have never heard of bees and butterflies, only moths, producing fertile eggs without copulation. With respect to the Ray Society, I profited so enormously by its publishing my Cirrepedia, that I cannot quite agree with you on confining it to translations; I know not how else I could possibly have published. I have just sent in my name for 20 pounds to the Linnaean Society, but I must confess I have done it with heavy groans, whereas I daresay you gave your 20 pounds like a light-hearted gentleman... P.S. Wollaston speaks strongly about the intermediate grade between two varieties in insects and mollusca being often rarer than the two varieties themselves. This is obviously very important for me, and not easy to explain. I believe I have had cases from you. But, if you believe in this, I wish you would give me a sentence to quote from you on this head. There must, I think, be a good deal of truth in it; otherwise there could hardly be nearly distinct varieties under any species, for we should have instead a blending series, as in brambles and willows. LETTER 49. TO J.D. HOOKER. July 13th, 1856. What a book a devil's chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel works of nature! With respect to crossing, from one sentence in your letter I think you misunderstand me. I am very far from believing in hybrids: only in crossing of the same species or of close varieties. These two or three last days I have been observing wheat, and have convinced myself that L. Deslongchamps is in error about impregnation taking place in closed flowers; i.e., of course, I can judge only from external appearances. By the way, R. Brown once told me that the use of the brush on stigma of grasses was unknown. Do you know its use?... You say most truly about multiple creations and my notions. If any one case could be proved, I should be smashed; but as I am writing my book, I try to take as much pains as possible to give the strongest cases opposed to me, and often such conjectures as occur to me. I have been working your books as the richest (and vilest) mine against me; and what hard work I have had to get up your New Zealand Flora! As I have to quote you so often, I should like to refer to Muller's case of the Australian Alps. Where is it published? Is it a book? A correct reference would be enough for me, though it is wrong even to quote without looking oneself. I should like to see very much Forbes's sheets, which you refer to; but I must confess (I hardly know why) I have got rather to mistrust poor dear Forbes. There is wonderful ill logic in his famous and admirable memoir on distribution, as it appears to me, now that I have got it up so as to give the heads in a page. Depend on it, my saying is a true one--viz. that a compiler is a great man, and an original man a commonplace man. Any fool can generalise and speculate; but oh, my heavens, to get up at second hand a New Zealand Flora, that is work... And now I am going to beg almost as great a favour as a man can beg of another: and I ask some five or six weeks before I want the favour done, that it may appear less horrid. It is to read, but well copied out, my pages (about forty!!) on Alpine floras and faunas, Arctic and Antarctic floras and faunas, and the supposed cold mundane period. It would be really an enormous advantage to me, as I am sure otherwise to make botanical blunders. I would specify the few points on which I most want your advice. But it is quite likely that you may object on the ground that you might be publishing before me (I hope to publish in a year at furthest), so that it would hamper and bother you; and secondly you may object to the loss of time, for I daresay it would take an hour and a half to read. It certainly would be of immense advantage to me; but of course you must not think of doing it if it would interfere with your own work. I do not consider this request in futuro as breaking my promise to give no more trouble for some time. From Lyell's letters, he is coming round at a railway pace on the mutability of species, and authorises me to put some sentences on this head in my preface. I shall meet Lyell on Wednesday at Lord Stanhope's, and will ask him to forward my letter to you; though, as my arguments have not struck him, they cannot have force, and my head must be crotchety on the subject; but the crotchets keep firmly there. I have given your opinion on continuous land, I see, too strongly. LETTER 50. TO S.P. WOODWARD. Down, July 18th [1856]. Very many thanks for your kindness in writing to me at such length, and I am glad to say for your sake that I do not see that I shall have to beg any further favours. What a range and what a variability in the Cyrena! (50/1. A genus of Lamellibranchs ranging from the Lias to the present day.) Your list of the ranges of the land and fresh-water shells certainly is most striking and curious, and especially as the antiquity of four of them is so clearly shown. I have got Harvey's seaside book, and liked it; I was not particularly struck with it, but I will re-read the first and last chapters. I am growing as bad as the worst about species, and hardly have a vestige of belief in the permanence of species left in me; and this confession will make you think very lightly of me, but I cannot help it. Such has become my honest conviction, though the difficulties and arguments against such heresy are certainly most weighty. LETTER 51. TO C. LYELL. November 10th [1856]. I know you like all cases of negative geological evidence being upset. I fancied that I was a most unwilling believer in negative evidence; but yet such negative evidence did seem to me so strong that in my "Fossil Lepadidae" I have stated, giving reasons, that I did not believe there could have existed any sessile cirripedes during the Secondary ages. Now, the other day Bosquet of Maestricht sends me a perfect drawing of a perfect Chthamalus (a recent genus) from the Chalk! (51/1. Chthamalus, a genus of Cirripedia. ("A Monograph on the Sub-class Cirripedia," by Charles Darwin, page 447. London, 1854.) A fossil species of this genus of Upper Cretaceous age was named by Bosquet Chthamalus Darwini. See "Origin," Edition VI., page 284; also Zittel, "Traite de Paleontologie," Traduit par Dr. C. Barrois, Volume II., page 540, figure 748. Paris, 1887.) Indeed, it is stretching a point to make it specifically distinct from our living British species. It is a genus not hitherto found in any Tertiary bed. LETTER 52. TO T.H. HUXLEY. Down, July 9th, 1857. I am extremely much obliged to you for having so fully entered on my point. I knew I was on unsafe ground, but it proves far unsafer than I had thought. I had thought that Brulle (52/1. This no doubt refers to A. Brulle's paper in the "Comptes rendus" 1844, of which a translation is given in the "Annals and Mag. of Natural History," 1844, page 484. In speaking of the development of the Articulata, the author says "that the appendages are manifested at an earlier period of the existence of an Articulate animal the more complex its degree of organisation, and vice versa that they make their appearance the later, the fewer the number of transformations which it has to undergo.") had a wider basis for his generalisation, for I made the extract several years ago, and I presume (I state it as some excuse for myself) that I doubted it, for, differently from my general habit, I have not extracted his grounds. It was meeting with Barneoud's paper which made me think there might be truth in the doctrine. (52/2. Apparently Barneoud "On the Organogeny of Irregular Corollas," from the "Comptes rendus," 1847, as given in "Annals and Mag. of Natural History," 1847, page 440. The paper chiefly deals with the fact that in their earliest condition irregular flowers are regular. The view attributed to Barneoud does not seem so definitely given in this paper as in a previous one ("Ann. Sc. Nat." Bot., Tom. VI., page 268.) Your instance of heart and brain of fish seems to me very good. It was a very stupid blunder on my part not thinking of the posterior part of the time of development. I shall, of course, not allude to this subject, which I rather grieve about, as I wished it to be true; but, alas! a scientific man ought to have no wishes, no affections--a mere heart of stone. There is only one point in your letter which at present I cannot quite follow you in: supposing that Barneoud's (I do not say Brulle's) remarks were true and universal--i.e., that the petals which have to undergo the greatest amount of development and modification begin to change the soonest from the simple and common embryonic form of the petal--if this were a true law, then I cannot but think that it would throw light on Milne Edwards' proposition that the wider apart the classes of animals are, the sooner do they diverge from the common embryonic plan--which common embryonic [plan] may be compared with the similar petals in the early bud, the several petals in one flower being compared to the distinct but similar embryos of the different classes. I much wish that you would so far keep this in mind, that whenever we meet I might hear how far you differ or concur in this. I have always looked at Barneoud's and Brulle's proposition as only in some degree analogous. P.S. I see in my abstract of Milne Edwards' paper, he speaks of "the most perfect and important organs" as being first developed, and I should have thought that this was usually synonymous with the most developed or modified. LETTER 53. TO J.D. HOOKER. (53/1. The following letter is chiefly of interest as showing the amount and kind of work required for Darwin's conclusions on "large genera varying," which occupy no more than two or three pages in the "Origin" (Edition I., page 55). Some correspondence on the subject is given in the "Life and Letters," II., pages 102-5.) Down, August 22nd [1857]. Your handwriting always rejoices the cockles of my heart; though you have no reason to be "overwhelmed with shame," as I did not expect to hear. I write now chiefly to know whether you can tell me how to write to Hermann Schlagenheit (is this spelt right?) (53/2. Schlagintweit.), for I believe he is returned to England, and he has poultry skins for me from W. Elliot of Madras. I am very glad to hear that you have been tabulating some Floras about varieties. Will you just tell me roughly the result? Do you not find it takes much time? I am employing a laboriously careful schoolmaster, who does the tabulating and dividing into two great cohorts, more carefully than I can. This being so, I should be very glad some time to have Koch, Webb's Canaries, and Ledebour, and Grisebach, but I do not know even where Rumelia is. I shall work the British flora with three separate Floras; and I intend dividing the varieties into two classes, as Asa Gray and Henslow give the materials, and, further, A. Gray and H.C. Watson have marked for me the forms, which they consider real species, but yet are very close to others; and it will be curious to compare results. If it will all hold good it is very important for me; for it explains, as I think, all classification, i.e. the quasi-branching and sub-branching of forms, as if from one root, big genera increasing and splitting up, etc., as you will perceive. But then comes in, also, what I call a principle of divergence, which I think I can explain, but which is too long, and perhaps you would not care to hear. As you have been on this subject, you might like to hear what very little is complete (for my schoolmaster has had three weeks' holidays)--only three cases as yet, I see. BABINGTON--British Flora. 593 species in genera of 5 and 593 (odd chance equal) in upwards have in a thousand genera of 3 and downwards have species presenting vars. in a thousand presenting vars. 134/1000.* 37/1000. (*53/3. This sentence may be interpreted as follows: The number of species which present varieties are 134 per thousand in genera of 5 species and upwards. The result is obtained from tabulation of 593 species.) HOOKER--New Zealand. Genera with 4 species and With 3 species and downwards upwards, 150/1000. 114/1000. GODRON--Central France. With 5 species and upwards With 3 species and downwards 160/1000. 105/1000. I do not enter into details on omitting introduced plants and very varying genera, as Rubus, Salix, Rosa, etc., which would make the result more in favour. I enjoyed seeing Henslow extremely, though I was a good way from well at the time. Farewell, my dear Hooker: do not forget your visit here some time. LETTER 54. TO J.D. HOOKER. Down, November 14th [1857]. On Tuesday I will send off from London, whither I go on that day, Ledebour's three remaining volumes, Grisebach and Cybele, i.e., all that I have, and most truly am I obliged to you for them. I find the rule, as yet, of the species varying most in the large genera universal, except in Miquel's very brief and therefore imperfect list of the Holland flora, which makes me very anxious to tabulate a fuller flora of Holland. I shall remain in London till Friday morning, and if quite convenient to send me two volumes of D.C. Prodromus, I could take them home and tabulate them. I should think a volume with a large best known natural family, and a volume with several small broken families would be best, always supposing that the varieties are conspicuously marked in both. Have you the volume published by Lowe on Madeira? If so and if any varieties are marked I should much like to see it, to see if I can make out anything about habitats of vars. in so small an area--a point on which I have become very curious. I fear there is no chance of your possessing Forbes and Hancock "British Shells," a grand work, which I much wish to tabulate. Very many thanks for seed of Adlumia cirrhosa, which I will carefully observe. My notice in the G. Ch. on Kidney Beans (54.1 "On the Agency of Bees in the Fertilisation of Papilionaceous Flowers" ("Gardeners' Chronicle," 1857, page 725).) has brought me a curious letter from an intelligent gardener, with a most remarkable lot of beans, crossed in a marvellous manner IN THE FIRST GENERATION, like the peas sent to you by Berkeley and like those experimentalised on by Gartner and by Wiegmann. It is a very odd case; I shall sow these seeds and see what comes up. How very odd that pollen of one form should affect the outer coats and size of the bean produced by pure species!... LETTER 55. TO J.D. HOOKER. Down [1857?]. You know how I work subjects: namely, if I stumble on any general remark, and if I find it confirmed in any other very distinct class, then I try to find out whether it is true,--if it has any bearing on my work. The following, perhaps, may be important to me. Dr. Wight remarks that Cucurbitaceae (55/1. Wight, "Remarks on the Fruit of the Natural Order Cucurbitaceae" ("Ann. Mag. Nat. Hist." VIII., page 261). R. Wight, F.R.S. (1796-1872) was Superintendent of the Madras Botanic Garden.) is a very isolated family, and has very diverging affinities. I find, strongly put and illustrated, the very same remark in the genera of hymenoptera. Now, it is not to me at first apparent why a very distinct and isolated group should be apt to have more divergent affinities than a less isolated group. I am aware that most genera have more affinities than in two ways, which latter, perhaps, is the commonest case. I see how infinitely vague all this is; but I should very much like to know what you and Mr. Bentham (if he will read this), who have attended so much to the principles of classification, think of this. Perhaps the best way would be to think of half a dozen most isolated groups of plants, and then consider whether the affinities point in an unusual number of directions. Very likely you may think the whole question too vague to be worth consideration. LETTER 56. TO J.D. HOOKER. Down, April 8th [1857]. I now want to ask your opinion, and for facts on a point; and as I shall often want to do this during the next year or two, so let me say, once for all, that you must not take trouble out of mere good nature (of which towards me you have a most abundant stock), but you must consider, in regard to the trouble any question may take, whether you think it worth while--as all loss of time so far lessens your original work--to give me facts to be quoted on your authority in my work. Do not think I shall be disappointed if you cannot spare time; for already I have profited enormously from your judgment and knowledge. I earnestly beg you to act as I suggest, and not take trouble solely out of good-nature. My point is as follows: Harvey gives the case of Fucus varying remarkably, and yet in same way under most different conditions. D. Don makes same remark in regard to Juncus bufonius in England and India. Polygala vulgaris has white, red, and blue flowers in Faroe, England, and I think Herbert says in Zante. Now such cases seem to me very striking, as showing how little relation some variations have to climatal conditions. Do you think there are many such cases? Does Oxalis corniculata present exactly the same varieties under very different climates? How is it with any other British plants in New Zealand, or at the foot of the Himalaya? Will you think over this and let me hear the result? One other question: do you remember whether the introduced Sonchus in New Zealand was less, equally, or more common than the aboriginal stock of the same species, where both occurred together? I forget whether there is any other case parallel with this curious one of the Sonchus... I have been making good, though slow, progress with my book, for facts have been falling nicely into groups, enlightening each other. LETTER 57. TO T.H. HUXLEY. Moor Park, Farnham, Surrey [1857?]. Your letter has been forwarded to me here, where I am profiting by a few weeks' rest and hydropathy. Your letter has interested and amused me much. I am extremely glad you have taken up the Aphis (57/1. Professor Huxley's paper on the organic reproduction of Aphis is in the "Trans. Linn. Soc." XXII. (1858), page 193. Prof. Owen had treated the subject in his introductory Hunterian lecture "On Parthenogenesis" (1849). His theory cannot be fully given here. Briefly, he holds that parthenogenesis is due to the inheritance of a "remnant of spermatic virtue": when the "spermatic force" or "virtue" is exhausted fresh impregnation occurs. Huxley severely criticises both Owen's facts and his theory.) question, but, for Heaven's sake, do not come the mild Hindoo (whatever he may be) to Owen; your father confessor trembles for you. I fancy Owen thinks much of this doctrine of his; I never from the first believed it, and I cannot but think that the same power is concerned in producing aphides without fertilisation, and producing, for instance, nails on the amputated stump of a man's fingers, or the new tail of a lizard. By the way, I saw somewhere during the last week or so a statement of a man rearing from the same set of eggs winged and wingless aphides, which seemed new to me. Does not some Yankee say that the American viviparous aphides are winged? I am particularly glad that you are ruminating on the act of fertilisation: it has long seemed to me the most wonderful and curious of physiological problems. I have often and often speculated for amusement on the subject, but quite fruitlessly. Do you not think that the conjugation of the Diatomaceae will ultimately throw light on the subject? But the other day I came to the conclusion that some day we shall have cases of young being produced from spermatozoa or pollen without an ovule. Approaching the subject from the side which attracts me most, viz., inheritance, I have lately been inclined to speculate, very crudely and indistinctly, that propagation by true fertilisation will turn out to be a sort of mixture, and not true fusion, of two distinct individuals, or rather of innumerable individuals, as each parent has its parents and ancestors. I can understand on no other view the way in which crossed forms go back to so large an extent to ancestral forms. But all this, of course, is infinitely crude. I hope to be in London in the course of this month, and there are two or three points which, for my own sake, I want to discuss briefly with you. LETTER 58. TO T.H. HUXLEY. Down, September 26th [1857]. Thanks for your very pleasant note. It amuses me to see what a bug-bear I have made myself to you; when having written some very pungent and good sentence it must be very disagreeable to have my face rise up like an ugly ghost. (58/1. This probably refers to Darwin's wish to moderate a certain pugnacity in Huxley.) I have always suspected Agassiz of superficiality and wretched reasoning powers; but I think such men do immense good in their way. See how he stirred up all Europe about glaciers. By the way, Lyell has been at the glaciers, or rather their effects, and seems to have done good work in testing and judging what others have done... In regard to classification and all the endless disputes about the "Natural System," which no two authors define in the same way, I believe it ought, in accordance to my heterodox notions, to be simply genealogical. But as we have no written pedigrees you will, perhaps, say this will not help much; but I think it ultimately will, whenever heterodoxy becomes orthodoxy, for it will clear away an immense amount of rubbish about the value of characters, and will make the difference between analogy and homology clear. The time will come, I believe, though I shall not live to see it, when we shall have very fairly true genealogical trees of each great kingdom of Nature. LETTER 59. TO T.H. HUXLEY. Down, December 16th [1857]. In my opinion your Catalogue (59/1. It appears from a letter to Sir J.D. Hooker (December 25th, 1857) that the reference is to the proofs of Huxley's "Explanatory Preface to the Catalogue of the Palaeontological Collection in the Museum of Practical Geology," by T.H. Huxley and R. Etheridge, 1865. Mr. Huxley appends a note at page xlix: "It should be noted that these pages were written before the appearance of Mr. Darwin's book on 'The Origin of Species'--a work which has effected a revolution in biological speculation.") is simply the very best resume, by far, on the whole science of Natural History, which I have ever seen. I really have no criticisms: I agree with every word. Your metaphors and explanations strike me as admirable. In many parts it is curious how what you have written agrees with what I have been writing, only with the melancholy difference for me that you put everything in twice as striking a manner as I do. I append, more for the sake of showing that I have attended to the whole than for any other object, a few most trivial criticisms. I was amused to meet with some of the arguments, which you advanced in talk with me, on classification; and it pleases me, [that] my long proses were so far not thrown away, as they led you to bring out here some good sentences. But on classification (59/2. This probably refers to Mr. Huxley's discussion on "Natural Classification," a subject hardly susceptible of fruitful treatment except from an evolutionary standpoint.) I am not quite sure that I yet wholly go with you, though I agree with every word you have here said. The whole, I repeat, in my opinion is admirable and excellent. LETTER 60. TO J.D. HOOKER. Down, February 28th [1858]. Hearty thanks for De Candolle received. I have put the big genera in hand. Also many thanks for your valuable remarks on the affinities of the species in great genera, which will be of much use to me in my chapter on classification. Your opinion is what I had expected from what little I knew, but I much wanted it confirmed, and many of your remarks were more or less new to me and all of value. You give a poor picture of the philosophy of Botany. From my ignorance, I suppose, I can hardly persuade myself that things are quite as bad as you make them,--you might have been writing remarks on Ornithology! I shall meditate much on your remarks, which will also come in very useful when I write and consider my tables of big and small genera. I grieve for myself to say that Watson agrees with your view, but with much doubt. I gave him no guide what your opinion was. I have written to A. Gray and to X., who--i.e. the latter--on this point may be looked at as S. Smith's Foolometer. I am now working several of the large local Floras, with leaving out altogether all the smallest genera. When I have done this, and seen what the sections of the largest genera say, and seen what the results are of range and commonness of varying species, I must come to some definite conclusion whether or not entirely to give up the ghost. I shall then show how my theory points, how the facts stand, then state the nature of your grievous assault and yield entirely or defend the case as far as I can honestly. Again I thank you for your invaluable assistance. I have not felt the blow [Hooker's criticisms] so much of late, as I have been beyond measure interested on the constructive instinct of the hive-bee. Adios, you terrible worrier of poor theorists! LETTER 61. TO J.D. HOOKER. Down [1858?] Many thanks for Ledebour and still more for your letter, with its admirable resume of all your objections. It is really most kind of you to take so very much trouble about what seems to you, and probably is, mere vagaries. I will earnestly try and be cautious. I will write out my tables and conclusion, and (when well copied out) I hope you will be so kind as to read it. I will then put it by and after some months look at it with fresh eyes. I will briefly work in all your objections and Watson's. I labour under a great difficulty from feeling sure that, with what very little systematic work I have done, small genera were more interesting and therefore more attracted my attention. One of your remarks I do not see the bearing of under your point of view--namely, that in monotypic genera "the variation and variability" are "much more frequently noticed" than in polytypic genera. I hardly like to ask, but this is the only one of your arguments of which I do not see the bearing; and I certainly should be very glad to know. I believe I am the slowest (perhaps the worst) thinker in England; and I now consequently fully admit the full hostility of Urticaceae, which I will give in my tables. I will make no remarks on your objections, as I do hope you will read my MS., which will not cost you much trouble when fairly copied out. From my own experience, I hardly believe that the most sagacious observers, without counting, could have predicted whether there were more or fewer recorded varieties in large or small genera; for I found, when actually making the list, that I could never strike a balance in my mind,--a good many varieties occurring together, in small or in large genera, always threw me off the balance... P.S.--I have just thought that your remark about the much variation of monotypic genera was to show me that even in these, the smallest genera, there was much variability. If this be so, then do not answer; and I will so understand it. LETTER 62. TO J.D. HOOKER. February 23rd [1858]. Will you think of some of the largest genera with which you are well acquainted, and then suppose 4/5 of the species utterly destroyed and unknown in the sections (as it were) as much as possible in the centre of such great genera. Then would the remaining 1/5 of the species, forming a few sections, be, according to the general practice of average good Botanists, ranked as distinct genera? Of course they would in that case be closely related genera. The question, in fact, is, are all the species in a gigantic genus kept together in that genus, because they are really so very closely similar as to be inseparable? or is it because no chasms or boundaries can be drawn separating the many species? The question might have been put for Orders. LETTER 63. TO J.D. HOOKER. Down, February 9th [1858]. I should be very much obliged for your opinion on the enclosed. You may remember in the three first volumes tabulated, all orders went right except Labiatae. By the way, if by any extraordinary chance you have not thrown away the scrap of paper with former results, I wish you would return it, for I have lost my copy, and I shall have all the division to do again; but DO NOT hunt for it, for in any case I should have gone over the calculation again. Now I have done the three other volumes. You will see that all species in the six volumes together go right, and likewise all orders in the three last volumes, except Verbenaceae. Is not Verbenaceae very closely allied to Labiatae? If so, one would think that it was not mere chance, this coincidence. The species in Labiatae and Verbenaceae together are between 1/5 and 1/6 of all the species (15,645), which I have now tabulated. Now, bearing in mind the many local Floras which I have tabulated (belting the whole northern hemisphere), and considering that they (and authors of D.C. Prodromus) would probably take different degrees of care in recording varieties, and the genera would be divided on different principles by different men, etc., I am much surprised at the uniformity of the result, and I am satisfied that there must be truth in the rule that the small genera vary less than the large. What do you think? Hypothetically I can conjecture how the Labiatae might fail--namely, if some small divisions of the Order were now coming into importance in the world and varying much and making species. This makes me want to know whether you could divide the Labiatae into a few great natural divisions, and then I would tabulate them separately as sub-orders. I see Lindley makes so many divisions that there would not be enough in each for an average. I send the table of the Labiatae for the chance of your being able to do this for me. You might draw oblique lines including and separating both large and small genera. I have also divided all the species into two equal masses, and my rule holds good for all the species in a mass in the six volumes; but it fails in several (four) large Orders--viz. Labiatae, Scrophulariaceae, Acanthaceae, and Proteaceae. But, then, when the species are divided into two almost exactly equal divisions, the divisions with large genera are so very few: for instance, in Solanaceae, Solanum balances all others. In Labiatae seven gigantic genera balance all others (viz. 113), and in Proteaceae five genera balance all others. Now, according to my hypothetical notions, I am far from supposing that all genera go on increasing forever, and therefore I am not surprised at this result, when the division is so made that only a very few genera are on one side. But, according to my notions, the sections or sub-genera of the gigantic genera ought to obey my rule (i.e., supposing a gigantic genus had come to its maximum, whatever increase was still going on ought to be going on in the larger sub-genera). Do you think that the sections of the gigantic genera in D.C. Prodromus are generally NATURAL: i.e. not founded on mere artificial characters? If you think that they are generally made as natural as they can be, then I should like very much to tabulate the sub-genera, considering them for the time as good genera. In this case, and if you do not think me unreasonable to ask it, I should be very glad of the loan of Volumes X., XI., XII., and XIV., which include Acanthaceae, Scrophulariaceae, Labiatae, and Proteaceae,--that is, the orders which, when divided quite equally, do not accord with my rule, and in which a very few genera balance all the others. I have written you a tremendous long prose. LETTER 64. TO J.D. HOOKER. Down, June 8th [1858]. I am confined to the sofa with boils, so you must let me write in pencil. You would laugh if you could know how much your note pleased me. I had the firmest conviction that you would say all my MS. was bosh, and thank God, you are one of the few men who dare speak the truth. Though I should not have much cared about throwing away what you have seen, yet I have been forced to confess to myself that all was much alike, and if you condemned that you would condemn all my life's work, and that I confess made me a little low; but I could have borne it, for I have the conviction that I have honestly done my best. The discussion comes in at the end of the long chapter on variation in a state of nature, so that I have discussed, as far as I am able, what to call varieties. I will try to leave out all allusion to genera coming in and out in this part, till when I discuss the "Principle of Divergence," which, with "Natural Selection," is the keystone of my book; and I have very great confidence it is sound. I would have this discussion copied out, if I could really think it would not bore you to read,--for, believe me, I value to the full every word of criticism from you, and the advantage which I have derived from you cannot be told... I am glad to hear that poor old Brown is dying so easily... You will think it paltry, but as I was asked to pay for printing the Diploma [from a Society of which he had been made an honorary member], I did not like to refuse, so I send 1 pound. But I think it a shabby proceeding. If a gentleman did me some service, though unasked to do it, and then demanded payment, I should pay him, and think him a shabby dog; and on this principle I send my 1 pound. (65/1. The following four letters refer to an inquiry instituted in 1858 by the Trustees of the British Museum as to the disposal of the Natural History Collections. The inquiry was one of the first steps towards the establishment of the Cromwell Road Museum, which was effected in 1875.) LETTER 65. TO R.I. MURCHISON. Down, June 19th [1858]. I have just received your note. Unfortunately I cannot attend at the British Museum on Monday. I do not suppose my opinion on the subject of your note can be of any value, as I have not much considered the subject, or had the advantage of discussing it with other naturalists. But my impression is, that there is much weight in what you say about not breaking up the natural history collection of the British Museum. I think a national collection ought to be in London. I can, however, see that some weighty arguments might be advanced in favour of Kew, owing to the immense value of Sir W. Hooker's collection and library; but these are private property, and I am not aware that there is any certainty of their always remaining at Kew. Had this been the case, I should have thought that the botanical collection might have been removed there without endangering the other branches of the collections. But I think it would be the greatest evil which could possibly happen to natural science in this country if the other collections were ever to be removed from the British Museum and Library. LETTER 66. TO T.H. HUXLEY. (66/1. The memorial referred to in the following letter was addressed on November 18th to the Chancellor of the Exchequer. It was signed by Huxley, Bentham, W.H. Harvey, Henfrey, Henslow, Lindley, Busk, Carpenter, and Darwin. The memorial, which is accessible, as published in the "Gardeners' Chronicle," November 27th, 1858, page 861, recommended, speaking generally, the consolidation of the National Botanical collections at Kew. In February, 1900, a Committee was appointed by the Lords Commissioners of the Treasury "to consider the present arrangements under which botanical work is done and collections maintained by the Trustees of the British Museum, and under the First Commissioner of Works at Kew, respectively; and to report what changes (if any) in those arrangements are necessary or desirable in order to avoid duplication of work and collections at the two institutions." The Committee published their report in March, 1901, recommending an arrangement similar to that proposed in 1858.) Down, October 23rd [1858]. The names which you give as supporting your memorial make me quite distrust my own judgment; but, as I must say yea or nay, I am forced to say that I doubt the wisdom of the movement, and am not willing at present to sign. My reasons, perhaps of very little value, are as follows. The governing classes are thoroughly unscientific, and the men of art and of archaeology have much greater weight with Government than we have. If we make a move to separate from the British Museum, I cannot but fear that we may go to the dogs. I think we owe our position in large part to the hundreds of thousands of people who visit the British Museum, attracted by the heterogeneous mixture of objects. If we lost this support, as I think we should--for a mere collection of animals does not seem very attractive to the masses (judging from the Museum of the Zoological Society, formerly in Leicester Square)--then I do not think we should get nearly so much aid from Government. Therefore I should be inclined to stick to the mummies and Assyrian gods as long as we could. If we knew that Government was going to turn us out, then, and not till then, I should be inclined to make an energetic move. If we were to separate, I do not believe that we should have funds granted for the many books required for occasional reference: each man must speak from his own experience. I have so repeatedly required to see old Transactions and old Travels, etc., that I should regret extremely, when at work at the British Museum, to be separated from the entire library. The facilities for working at certain great classes--as birds, large fossils, etc.--are no doubt as bad as possible, or rather impossible, on the open days; but I have found the working rooms of the Assistants very convenient for all other classes on all days. In regard to the botanical collections, I am too ignorant to express any opinion. The point seems to be how far botanists would object to travel to Kew; but there are evidently many great advantages in the transportation. If I had my own way, I would make the British Museum collection only a typical one for display, which would be quite as amusing and far more instructive to the populace (and I think to naturalists) than the present enormous display of birds and mammals. I would save expense of stuffing, and would keep all skins, except a few "typicals," in drawers. Thus much room would be saved, and a little more space could be given to real workers, who could work all day. Rooms fitted up with thousands of drawers would cost very little. With this I should be contented. Until I had pretty sure information that we were going to be turned out, I would not stir in the matter. With such opponents as you name, I daresay I am quite wrong; but this is my best, though doubtful, present judgment... It seems to me dangerous even to hint at a new Scientific Museum--a popular Museum, and to subsidise the Zoological Gardens; it would, I think, frighten any Government. LETTER 67. TO J.D. HOOKER. Moor Park, Farnham, Surrey [October] 29th [1858]. As you say that you have good private information that Government does intend to remove the collection from the British Museum, the case to me individually is wholly changed; and as the memorial now stands, with such expression at its head, I have no objection whatever to sign. I must express a very strong opinion that it would be an immense evil to remove to Kensington, not on account of the men of science so much as for the masses in the whole eastern and central part of London. I further think it would be a great evil to separate a typical collection (which I can by no means look at as only popular) from the collection in full. Might not some expression be added, even stronger than those now used, on the display (which is a sort of vanity in the curators) of such a vast number of birds and mammals, with such a loss of room. I am low at the conviction that Government will never give money enough for a really good library. I do not want to be crotchety, but I should hate signing without some expression about the site being easily accessible to the populace of the whole of London. I repeat, as things now stand, I shall be proud to sign. LETTER 68. TO T.H. HUXLEY. Down, November 3rd [1858]. I most entirely subscribe to all you say in your note. I have had some correspondence with Hooker on the subject. As it seems certain that a movement in the British Museum is generally anticipated, my main objection is quite removed; and, as I have told Hooker, I have no objection whatever to sign a memorial of the nature of the one he sent me or that now returned. Both seem to me very good. I cannot help being fearful whether Government will ever grant money enough for books. I can see many advantages in not being under the unmotherly wing of art and archaeology, and my only fear was that we were not strong enough to live without some protection, so profound, I think, is the contempt for and ignorance of Natural Science amongst the gentry of England. Hooker tells me that I should be converted into favour of Kensington Gore if I heard all that could be said in its favour; but I cannot yet help thinking so western a locality a great misfortune. Has Lyell been consulted? His would be a powerful name, and such names go for much with our ignorant Governors. You seem to have taken much trouble in the business, and I honour you for it. LETTER 69. TO J.D. HOOKER. Down, November 9th [1858]. I am quite delighted to hear about the Copley and Lyell. (69/1. The Copley Medal of the Royal Society was awarded to Lyell in 1858.) I have grown hot with indignation many times thinking of the way the proposal was met last year, according to your account of it. I am also very glad to hear of Hancock (Albany Hancock received a Royal Medal in 1858.); it will show the provincials are not neglected. Altogether the medals are capital. I shall be proud and bound to help in any way about the eloge, which is rather a heavy tax on proposers of medals, as I found about Richardson and Westwood; but Lyell's case will be twenty times as difficult. I will begin this very evening dotting down a few remarks on Lyell; though, no doubt, most will be superfluous, and several would require deliberate consideration. Anyhow, such notes may be a preliminary aid to you; I will send them in a few days' time, and will do anything else you may wish... P.S.--I have had a letter from Henslow this morning. He comes here on [Thursday] 25th, and I shall be delighted to see him; but it stops my coming to the Club, as I had arranged to do, and now I suppose I shall not be in London till December 16th, if odds and ends do not compel me to come sooner. Of course I have not said a word to Henslow of my change of plans. I had looked forward with pleasure to a chat with you and others. P.S. 2.--I worked all yesterday evening in thinking, and have written the paper sent by this post this morning. Not one sentence would do, but it is the sort of rough sketch which I should have drawn out if I had had to do it. God knows whether it will at all aid you. It is miserably written, with horridly bad metaphors, probably horrid bad grammar. It is my deliberate impression, such as I should have written to any friend who had asked me what I thought of Lyell's merits. I will do anything else which you may wish, or that I can. LETTER 70. TO J.D. HOOKER. Down, December 30th [1858]. I have had this copied to save you trouble, as it was vilely written, and is now vilely expressed. Your letter has interested me greatly; but how inextricable are the subjects which we are discussing! I do not think I said that I thought the productions of Asia were HIGHER (70/1. On the use of the terms "higher" and "lower" see Letters 35 and 36.) than those of Australia. I intend carefully to avoid this expression (70/2. In a paper of pencilled notes pinned into Darwin's copy of the "Vestiges" occur the words: "Never use the word (sic) higher and lower."), for I do not think that any one has a definite idea what is meant by higher, except in classes which can loosely be compared with man. On our theory of Natural Selection, if the organisms of any area belonging to the Eocene or Secondary periods were put into competition with those now existing in the same area (or probably in any part of the world) they (i.e. the old ones) would be beaten hollow and be exterminated; if the theory be true, this must be so. In the same manner, I believe, a greater number of the productions of Asia, the largest territory in the world, would beat those of Australia, than conversely. So it seems to be between Europe and North America, for I can hardly believe in the difference of the stream of commerce causing so great a difference in the proportions of immigrants. But this sort of highness (I wish I could invent some expression, and must try to do so) is different from highness in the common acceptation of the word. It might be connected with degradation of organisation: thus the blind degraded worm-like snake (Typhlops) might supplant the true earthworm. Here then would be degradation in the class, but certainly increase in the scale of organisation in the general inhabitants of the country. On the other hand, it would be quite as easy to believe that true earthworms might beat out the Typhlops. I do not see how this "competitive highness" can be tested in any way by us. And this is a comfort to me when mentally comparing the Silurian and Recent organisms. Not that I doubt a long course of "competitive highness" will ultimately make the organisation higher in every sense of the word; but it seems most difficult to test it. Look at the Erigeron canadensis on the one hand and Anacharis (70/3. Anacharis (Elodea canadensis) and Erigeron canadensis are both successful immigrants from America.) on the other; these plants must have some advantage over European productions, to spread as they have. Yet who could discover it? Monkeys can co-exist with sloths and opossums, orders at the bottom of the scale; and the opossums might well be beaten by placental insectivores, coming from a country where there were no monkeys, etc. I should be sorry to give up the view that an old and very large continuous territory would generally produce organisms higher in the competitive sense than a smaller territory. I may, of course, be quite wrong about the plants of Australia (and your facts are, of course, quite new to me on their highness), but when I read the accounts of the immense spreading of European plants in Australia, and think of the wool and corn brought thence to Europe, and not one plant naturalised, I can hardly avoid the suspicion that Europe beats Australia in its productions. If many (i.e. more than one or two) Australian plants are TRULY naturalised in India (N.B. Naturalisation on Indian mountains hardly quite fair, as mountains are small islands in the land) I must strike my colours. I should be glad to hear whether what I have written very obscurely on this point produces ANY effect on you; for I want to clear my mind, as perhaps I should put a sentence or two in my abstract on this subject. (70/4. Abstract was Darwin's name for the "Origin" during parts of 1858 and 1859.) I have always been willing to strike my colours on former immense tracts of land in oceans, if any case required it in an eminent degree. Perhaps yours may be a case, but at present I greatly prefer land in the Antarctic regions, where now there is only ice and snow, but which before the Glacial period might well have been clothed by vegetation. You have thus to invent far less land, and that more central; and aid is got by floating ice for transporting seed. I hope I shall not weary you by scribbling my notions at this length. After writing last to you I began to think that the Malay Land might have existed through part of the Glacial epoch. Why I at first doubted was from the difference of existing mammals in different islands; but many are very close, and some identical in the islands, and I am constantly deceiving myself from thinking of the little change which the shells and plants, whilst all co-existing in their own northern hemisphere, have undergone since the Glacial epoch; but I am convinced that this is most false reasoning, for the relations of organism to new organisms, when thrown together, are by far the most important. When you speak of plants having undergone more change since old geological periods than animals, are you not rather comparing plants with higher animals? Think how little some, indeed many, mollusca have changed. Remember Silurian Nautilus, Lingula and other Brachiopods, and Nucula, and amongst Echinoderms, the Silurian Asterias, etc. What you say about lowness of brackish-water plants interests me. I remember that they are apt to be social (i.e. many individuals in comparison to specific forms), and I should be tempted to look at this as a case of a very small area, and consequently of very few individuals in comparison with those on the land or in pure fresh-water; and hence less development (odious word!) than on land or fresh-water. But here comes in your two-edged sword! I should like much to see any paper on plants of brackish water or on the edge of the sea; but I suppose such has never been published. Thanks about Nelumbium, for I think this was the very plant which from the size of seed astonished me, and which A. De Candolle adduced as a marvellous case of almost impossible transport. I now find to my surprise that herons do feed sometimes on [illegible] fruit; and grebes on seeds of Compositae. Many thanks for offer of help about a grant for the Abstract; but I should hope it would sell enough to pay expenses. I am reading your letter and scribbling as I go on. Your oak and chestnut case seems very curious; is it not the more so as beeches have gone to, or come from the south? But I vehemently protest against you or any one making such cases especial marvels, without you are prepared to say why each species in any flora is twice or thrice, etc., rarer than each other species which grows in the same soil. The more I think, the more evident is it to me how utterly ignorant we are of the thousand contingencies on which range, frequency, and extinction of each species depend. I have sometimes thought, from Edentata (70/5. No doubt a slip of the pen for Monotremata.) and Marsupialia, that Australia retains a remnant of the former and ancient state of the fauna of the world, and I suppose that you are coming to some such conclusion for plants; but is not the relation between the Cape and Australia too special for such views? I infer from your writings that the relation is too special between Fuegia and Australia to allow us to look at the resemblances in certain plants as the relics of mundane resemblances. On the other hand, [have] not the Sandwich Islands in the Northern Hemisphere some odd relations to Australia? When we are dead and gone what a noble subject will be Geographical Distribution! You may say what you like, but you will never convince me that I do not owe you ten times as much as you can owe me. Farewell, my dear Hooker. I am sorry to hear that you are both unwell with influenza. Do not bother yourself in answering anything in this, except your general impression on the battle between N. and S. CHAPTER 1.III.--EVOLUTION, 1859-1863. LETTER 71. TO A.R. WALLACE. Down, April 6th, 1859. I this morning received your pleasant and friendly note of November 30th. The first part of my MS. is in Murray's hands to see if he likes to publish it. There is no preface, but a short introduction, which must be read by every one who reads my book. The second paragraph in the introduction (71/1. "Origin of Species," Edition I., 1859, pages 1 and 2.) I have had copied verbatim from my foul copy, and you will, I hope, think that I have fairly noticed your paper in the "Linn. Journal." (71/2. "On the Tendency of Species to form Varieties, and on the Perpetuation of Varieties and Species by Natural Means of Selection." By Charles Darwin and Alfred Russell Wallace. Communicated by Sir Charles Lyell and J.D. Hooker. "Journ. Linn. Soc." Volume III., page 45, 1859. (Read July 1st, 1858.)) You must remember that I am now publishing only an abstract, and I give no references. I shall, of course, allude to your paper on distribution (71/3. "On the Law which has regulated the Introduction of New Species" (A.R. Wallace). "Ann. Mag. Nat. Hist." Volume XVI., page 184, 1855. The law alluded to is thus stated by Wallace: "Every species has come into existence coincident both in space and time with a pre-existing closely allied species" (loc. cit., page 186).); and I have added that I know from correspondence that your explanation of your law is the same as that which I offer. You are right, that I came to the conclusion that selection was the principle of change from the study of domesticated productions; and then, reading Malthus, I saw at once how to apply this principle. Geographical distribution and geological relations of extinct to recent inhabitants of South America first led me to the subject: especially the case of the Galapagos Islands. I hope to go to press in the early part of next month. It will be a small volume of about five hundred pages or so. I will of course send you a copy. I forget whether I told you that Hooker, who is our best British botanist and perhaps the best in the world, is a full convert, and is now going immediately to publish his confession of faith; and I expect daily to see proof-sheets. (71/4. "The Flora of Australia, etc., an Introductory Essay to the Flora of Tasmania." London 1859.) Huxley is changed, and believes in mutation of species: whether a convert to us, I do not quite know. We shall live to see all the younger men converts. My neighbour and an excellent naturalist, J. Lubbock, is an enthusiastic convert. I see that you are doing great work in the Archipelago; and most heartily do I sympathise with you. For God's sake take care of your health. There have been few such noble labourers in the cause of Natural Science as you are. P.S. You cannot tell how I admire your spirit, in the manner in which you have taken all that was done about publishing all our papers. I had actually written a letter to you, stating that I would not publish anything before you had published. I had not sent that letter to the post when I received one from Lyell and Hooker, urging me to send some MS. to them, and allow them to act as they thought fair and honestly to both of us; and I did so. (71/5. The following is the passage from the Introduction to the "Origin of Species," referred to in the first paragraph of the above letter.) "My work is now nearly finished; but as it will take me two or three years more to complete it, and as my health is far from strong, I have been urged to publish this Abstract. I have more especially been induced to do this, as Mr. Wallace, who is now studying the Natural History of the Malay Archipelago, has arrived at almost exactly the same general conclusions that I have on the origin of species. Last year he sent to me a memoir on this subject, with a request that I would forward it to Sir Charles Lyell, who sent it to the Linnean Society, and it is published in the third volume of the Journal of that Society. Sir C. Lyell and Dr. Hooker, who both knew of my work--the latter having read my sketch of 1844--honoured me by thinking it advisable to publish, with Mr. Wallace's excellent memoir, some brief extracts from my manuscripts." LETTER 72. TO J.D. HOOKER. Down, May 3rd, 1859. With respect to reversion, I have been raking up vague recollections of vague facts; and the impression on my mind is rather more in favour of reversion than it was when you were here. In my abstract (72/1. "The Origin of Species.") I give only a paragraph on the general case of reversion, though I enter in detail on some cases of reversion of a special character. I have not as yet put all my facts on this subject in mass, so can come to no definite conclusion. But as single characters may revert, I must say that I see no improbability in several reverting. As I do not believe any well-founded experiments or facts are known, each must form his opinion from vague generalities. I think you confound two rather distinct considerations; a variation arises from any cause, and reversion is not opposed to this, but solely to its inheritance. Not but what I believe what we must call perhaps a dozen distinct laws are all struggling against each other in every variation which ever arises. To give my impression, if I were forced to bet whether or not, after a hundred generations of growth in a poor sandy soil, a cauliflower and red cabbage would or would not revert to the same form, I must say I would rather stake my money that they would. But in such a case the conditions of life are changed (and here comes the question of direct influence of condition), and there is to be no selection, the comparatively sudden effect of man's selection are left to the free play of reversion. In short, I dare not come to any conclusion without comparing all facts which I have collected, and I do not think there are many. Please do not say to any one that I thought my book on species would be fairly popular and have a fairly remunerative sale (which was the height of my ambition), for if it prove a dead failure it would make me the more ridiculous. LETTER 73. TO W.H. MILLER. Down, June 5th [1859]. I thank you much for your letter. Had I seen the interest of my remark I would have made many more measurements, though I did make several. I stated the facts merely to give the general reader an idea of the thickness of the walls. (73/1. The walls of bees' cells: see Letter 173.) Especially if I had seen that the fact had any general bearing, I should have stated that as far as I could measure, the walls are by no means perfectly of the same thickness. Also I should have stated that the chief difference is when the thickness of walls of the upper part of the hexagon and of the pyramidal basal plates are contrasted. Will you oblige me by looking with a strong lens at the bit of comb, brushing off with a knife the upper thickened edges, and then compare, by eye alone, the thickness of the walls there with the thickness of the basal plates, as seen in any cross section. I should very much like to hear whether, even in this way, the difference is not perceptible. It is generally thus perceptible by comparing the thickness of the walls of the hexagon (if not taken very close to the angle) near to the basal plates, where the comparison by eye is of course easier. Your letter actually turned me sick with panic; from not seeing any great importance [in the] fact, till I looked at my notes, I did not remember that I made several measurements. I have now repeated the same measurements, roughly with the same general results, but the difference, I think, is hardly double. I should not have mentioned the thickness of the basal plates at all, had I not thought it would give an unfair notion of the thickness of the walls to state the lesser measurements alone. LETTER 74. TO W.H. MILLER. [1859] I had no thought that you would measure the thickness of the walls of the cells; but if you will, and allow me to give your measurements, it will be an immense advantage. As it is no trouble, I send more specimens. If you measure, please observe that I measured the thickness of the walls of the hexagonal prisms not very near the base; but from your very interesting remarks the lower part of the walls ought to be measured. Thank you for the suggestion about how bees judge of angles and distances. I will keep it in mind. It is a complete perplexity to me, and yet certainly insects can rudely somehow judge of distance. There are special difficulties on account of the gradation in size between the worker-scells and the larger drone-cells. I am trying to test the case practically by getting combs of different species, and of our own bee from different climates. I have lately had some from the W. Indies of our common bee, but the cells SEEM certainly to be larger; but they have not yet been carefully measured. I will keep your suggestion in mind whenever I return to experiments on living bees; but that will not be soon. As you have been considering my little discussion in relation to Lord Brougham (74/1. Lord Brougham's paper on "The Mathematical Structure of Bees' Cells," read before the National Institute of France in May, 1858.), and as I have been more vituperated for this part than for almost any other, I should like just to tell you how I think the case stands. The discussion viewed by itself is worth little more than the paper on which it is printed, except in so far as it contains three or four certainly new facts. But to those who are inclined to believe the general truth of the conclusion that species and their instincts are slowly modified by what I call Natural Selection, I think my discussion nearly removes a very great difficulty. I believe in its truth chiefly from the existence of the Melipona, which makes a comb so intermediate in structure between that of the humble and hive-bee, and especially from the new and curious fact of the bees making smooth cups or saucers when they excavated in a thick piece of wax, which saucers stood so close that hexagons were built on their intersecting edges. And, lastly, because when they excavated on a thin slip of wax, the excavation on both sides of similar smooth basins was stopped, and flat planes left between the nearly opposed basins. If my view were wholly false these cases would, I think, never have occurred. Sedgwick and Co. may abuse me to their hearts' content, but I shall as yet continue to think that mine is a rational explanation (as far as it goes) of their method of work. LETTER 75. TO W.H. MILLER. Down, December 1st [1859]. Some months ago you were so kind as to say you would measure the thickness of the walls of the basal and side plates of the cell of the bee. Could you find time to do so soon? Why I want it soon, is that I have lately heard from Murray that he sold at his sale far more copies than he has of the "Origin of Species," and that I must immediately prepare a new edition, which I am now correcting. By the way, I hear from Murray that all the attacks heaped on my book do not seem to have at all injured the sale, which will make poor dear old Sedgwick groan. If the basal plates and walls do differ considerably in thickness, as they certainly did in the one or two cells which I measured without particular care (as I never thought the point of any importance), will you tell me the bearing of the fact as simply as you can, for the chance of one so stupid as I am in geometry being able to understand? Would the greater thickness of the basal plates and of the rim of the hexagons be a good adaptation to carry the vertical weight of the cells filled with honey and supporting clusters of living bees? Will you endeavour to screw out time and grant me this favour? P.S. If the result of your measurement of the thickness of the walls turns out at all what I have asserted, would it not be worth while to write a little bit of a paper on the subject of your former note; and "pluck" the bees if they deserve this degradation? Many mathematicians seem to have thought the subject worthy of attention. When the cells are full of honey and hang vertically they have to support a great weight. Can the thicker basal plates be a contrivance to give strength to the whole comb, with less consumption of wax, than if all the sides of the hexagons were thickened? This crude notion formerly crossed my mind; but of course it is beyond me even to conjecture how the case would be. A mathematician, Mr. Wright, has been writing on the geometry of bee-cells in the United States in consequence of my book; but I can hardly understand his paper. (75/1. Chauncey Wright, "Remarks on the Architecture of Bees" ("Amer. Acad. Proc." IV., 1857-60, page 432.) LETTER 76. TO T.H. HUXLEY. (76/1. The date of this letter is unfortunately doubtful, otherwise it would prove that at an early date he was acquainted with Erasmus Darwin's views on evolution, a fact which has not always been recognised. We can hardly doubt that it was written in 1859, for at this time Mr. Huxley was collecting facts about breeding for his lecture given at the Royal Institution on February 10th, 1860, on "Species and Races and their Origin." See "Life and Letters," II., page 281.) Down [June?] 9 [1859?]. If on the 11th you have half an hour to spare, you might like to see a very good show of pigeons, and the enclosed card will admit you. The history of error is quite unimportant, but it is curious to observe how exactly and accurately my grandfather (in "Zoonomia," Volume I., page 504, 1794) gives Lamarck's theory. I will quote one sentence. Speaking of birds' beaks, he says: "All which seem to have been gradually produced during many generations by the perpetual endeavour of the creatures to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purposes required." Lamarck published "Hist. Zoolog." in 1809. The "Zoonomia" was translated into many languages. LETTER 77. TO C. LYELL. Down, 28 [June 1859]. It is not worth while troubling you, but my conscience is uneasy at having forgotten to thank you for your "Etna" (77/1. "On the Structure of Lavas which have been consolidated on Steep Slopes, with remarks on the Mode of Origin of Mount Etna, and on the Theory of 'Craters of Elevation'" ("Phil. Trans. R. Soc." Volume CXLVIII., 1858, page 703).), which seems to me a magnificent contribution to volcanic geology, and I should think you might now rest on your oars in this department. As soon as ever I can get a copy of my book (77/2. "The Origin of Species," London, 1859.) ready, in some six weeks' or two months' time, it shall be sent you; and if you approve of it, even to a moderate extent, it will be the highest satisfaction which I shall ever receive for an amount of labour which no one will ever appreciate. LETTER 78. TO J.D. HOOKER. (78/1. The reference in the following letter is to the proofs of Hooker's "Australian Flora.") Down, 28 [July 1859]. The returned sheet is chiefly that which I received in MS. Parts seem to me (though perhaps it may be forgetfulness) much improved, and I retain my former impression that the whole discussion on the Australian flora is admirably good and original. I know you will understand and not object to my thus expressing my opinion (for one must form one) so presumptuously. I have no criticisms, except perhaps I should like you somewhere to say, when you refer to me, that you refer only to the notice in the "Linnean Journal;" not that, on my deliberate word of honour, I expect that you will think more favourably of the whole than of the suggestion in the "Journal." I am far more than satisfied at what you say of my work; yet it would be as well to avoid the appearance of your remarks being a criticism on my fuller work. I am very sorry to hear you are so hard-worked. I also get on very slowly, and have hardly as yet finished half my volume...I returned on last Tuesday from a week's hydropathy. Take warning by me, and do not work too hard. For God's sake, think of this. It is dreadfully uphill work with me getting my confounded volume finished. I wish you well through all your labours. Adios. LETTER 79. TO ASA GRAY. Down, November 29th [1859]. This shall be such an extraordinary note as you have never received from me, for it shall not contain one single question or request. I thank you for your impression on my views. Every criticism from a good man is of value to me. What you hint at generally is very, very true: that my work will be grievously hypothetical, and large parts by no means worthy of being called induction, my commonest error being probably induction from too few facts. I had not thought of your objection of my using the term "natural selection" as an agent. I use it much as a geologist does the word denudation--for an agent, expressing the result of several combined actions. I will take care to explain, not merely by inference, what I mean by the term; for I must use it, otherwise I should incessantly have to expand it into some such (here miserably expressed) formula as the following: "The tendency to the preservation (owing to the severe struggle for life to which all organic beings at some time or generation are exposed) of any, the slightest, variation in any part, which is of the slightest use or favourable to the life of the individual which has thus varied; together with the tendency to its inheritance." Any variation, which was of no use whatever to the individual, would not be preserved by this process of "natural selection." But I will not weary you by going on, as I do not suppose I could make my meaning clearer without large expansion. I will only add one other sentence: several varieties of sheep have been turned out together on the Cumberland mountains, and one particular breed is found to succeed so much better than all the others that it fairly starves the others to death. I should here say that natural selection picks out this breed, and would tend to improve it, or aboriginally to have formed it... You speak of species not having any material base to rest on, but is this any greater hardship than deciding what deserves to be called a variety, and be designated by a Greek letter? When I was at systematic work, I know I longed to have no other difficulty (great enough) than deciding whether the form was distinct enough to deserve a name, and not to be haunted with undefined and unanswerable questions whether it was a true species. What a jump it is from a well-marked variety, produced by natural cause, to a species produced by the separate act of the hand of God! But I am running on foolishly. By the way, I met the other day Phillips, the palaeontologist, and he asked me, "How do you define a species?" I answered, "I cannot." Whereupon he said, "at last I have found out the only true definition,--any form which has ever had a specific name!"... LETTER 80. TO C. LYELL. Ilkley, October 31st [1859]. That you may not misunderstand how far I go with Pallas and his many disciples I should like to add that, though I believe that our domestic dogs have descended from several wild forms, and though I must think that the sterility, which they would probably have evinced, if crossed before being domesticated, has been eliminated, yet I go but a very little way with Pallas & Co. in their belief in the importance of the crossing and blending of the aboriginal stocks. (80/1. "With our domesticated animals, the various races when crossed together are quite fertile; yet in many cases they are descended from two or more wild species. From this fact we must conclude either that the aboriginal parent-species at first produced perfectly fertile hybrids, or that the hybrids subsequently reared under domestication became quite fertile. This latter alternative, which was first propounded by Pallas, seems by far the most probable, and can, indeed, hardly be doubted" ("Origin of Species," Edition VI., page 240).) You will see this briefly put in the first chapter. Generally, with respect to crossing, the effects may be diametrically opposite. If you cross two very distinct races, you may make (not that I believe such has often been made) a third and new intermediate race; but if you cross two exceedingly close races, or two slightly different individuals of the same race, then in fact you annul and obliterate the difference. In this latter way I believe crossing is all-important, and now for twenty years I have been working at flowers and insects under this point of view. I do not like Hooker's terms, centripetal and centrifugal (80/2. Hooker's "Introductory Essay to the Flora of Tasmania," pages viii. and ix.): they remind me of Forbes' bad term of Polarity. (80/3. Forbes, "On the Manifestation of Polarity in the Distribution of Organised Beings in Time."--"R. Institution Proc." I., 1851-54.) I daresay selection by man would generally work quicker than Natural Selection; but the important distinction between them is, that man can scarcely select except external and visible characters, and secondly, he selects for his own good; whereas under nature, characters of all kinds are selected exclusively for each creature's own good, and are well exercised; but you will find all this in Chapter IV. Although the hound, greyhound, and bull-dog may possibly have descended from three distinct stocks, I am convinced that their present great amount of difference is mainly due to the same causes which have made the breeds of pigeons so different from each other, though these breeds of pigeons have all descended from one wild stock; so that the Pallasian doctrine I look at as but of quite secondary importance. In my bigger book I have explained my meaning fully; whether I have in the Abstract I cannot remember. LETTER 81. TO C. LYELL. [December 5th, 1859.] I forget whether you take in the "Times;" for the chance of your not doing so, I send the enclosed rich letter. (81/1. See the "Times," December 1st and December 5th, 1859: two letters signed "Senex," dealing with "Works of Art in the Drift.") It is, I am sure, by Fitz-Roy...It is a pity he did not add his theory of the extinction of Mastodon, etc., from the door of the Ark being made too small. (81/2. A postscript to this letter, here omitted, is published in the "Life and Letters," II., page 240.) LETTER 82. FRANCIS GALTON TO CHARLES DARWIN. 42, Rutland Gate, London, S.W., December 9th, 1859. Pray let me add a word of congratulation on the completion of your wonderful volume, to those which I am sure you will have received from every side. I have laid it down in the full enjoyment of a feeling that one rarely experiences after boyish days, of having been initiated into an entirely new province of knowledge, which, nevertheless, connects itself with other things in a thousand ways. I hear you are engaged on a second edition. There is a trivial error in page 68, about rhinoceroses (82/1. Down (loc. cit.) says that neither the elephant nor the rhinoceros is destroyed by beasts of prey. Mr. Galton wrote that the wild dogs hunt the young rhinoceros and "exhaust them to death; they pursue them all day long, tearing at their ears, the only part their teeth can fasten on." The reference to the rhinoceros is omitted in later editions of the "Origin."), which I thought I might as well point out, and have taken advantage of the same opportunity to scrawl down half a dozen other notes, which may, or may not, be worthless to you. (83/1. The three next letters refer to Huxley's lecture on Evolution, given at the Royal Institution on February 10th, 1860, of which the peroration is given in "Life and Letters," II., page 282, together with some letters on the subject.) LETTER 83. TO T.H. HUXLEY. November 25th [1859]. I rejoice beyond measure at the lecture. I shall be at home in a fortnight, when I could send you splendid folio coloured drawings of pigeons. Would this be in time? If not, I think I could write to my servants and have them sent to you. If I do NOT hear I shall understand that about fifteen or sixteen days will be in time. I have had a kind yet slashing letter against me from poor dear old Sedgwick, "who has laughed till his sides ached at my book." Phillips is cautious, but decidedly, I fear, hostile. Hurrah for the Lecture--it is grand! LETTER 84. TO T.H. HUXLEY. Down, December 13th [1859]. I have got fine large drawings (84/1. For Mr. Huxley's R.I. lecture.) of the Pouter, Carrier, and Tumbler; I have only drawings in books of Fantails, Barbs, and Scanderoon Runts. If you had them, you would have a grand display of extremes of diversity. Will they pay at the Royal Institution for copying on a large size drawings of these birds? I could lend skulls of a Carrier and a Tumbler (to show the great difference) for the same purpose, but it would not probably be worth while. I have been looking at my MS. What you want I believe is about hybridism and breeding. The chapter on hybridism is in a pretty good state--about 150 folio pages with notes and references on the back. My first chapter on breeding is in too bad and imperfect a state to send; but my discussion on pigeons (in about 100 folio pages) is in a pretty good state. I am perfectly convinced that you would never have patience to read such volumes of MS. I speak now in the palace of truth, and pray do you: if you think you would read them I will send them willingly up by my servant, or bring them myself next week. But I have no copy, and I never could possibly replace them; and without you really thought that you would use them, I had rather not risk them. But I repeat I will willingly bring them, if you think you would have the vast patience to use them. Please let me hear on this subject, and whether I shall send the book with small drawings of three other breeds or skulls. I have heard a rumour that Busk is on our side in regard to species. Is this so? It would be very good. LETTER 85. TO T.H. HUXLEY. Down, December 16th [1859]. I thank you for your very pleasant and amusing note and invitation to dinner, which I am sorry to say I cannot accept. I shall come up (stomach willing) on Thursday for Phil. Club dinner, and return on Saturday, and I am engaged to my brother for Friday. But I should very much like to call at the Museum on Friday or Saturday morning and see you. Would you let me have one line either here or at 57, Queen Anne Street, to say at what hour you generally come to the Museum, and whether you will be probably there on Friday or Saturday? Even if you are at the Club, it will be a mere chance if we sit near each other. I will bring up the articles on Thursday afternoon, and leave them under charge of the porter at the Museum. They will consist of large drawings of a Pouter, a Carrier, and rather smaller drawings of some sub-varieties (which breed nearly true) of short-faced Tumblers. Also a small drawing of Scanderoon, a kind of Runt, and a very remarkable breed. Also a book with very moderately good drawings of Fantail and Barb, but I very much doubt whether worth the trouble of enlarging. Also a box (for Heaven's sake, take care!) with a skull of Carrier and short-faced Tumbler; also lower jaws (largest size) of Runt, middle size of Rock-pigeon, and the broad one of Barb. The form of ramus of jaw differs curiously in these jaws. Also MS. of hybridism and pigeons, which will just weary you to death. I will call myself for or send a servant for the MS. and bones whenever you have done with them; but do not hurry. You have hit on the exact plan, which, on the advice of Lyell, Murray, etc., I mean to follow--viz., bring out separate volumes in detail--and I shall begin with domestic productions; but I am determined to try and [work] very slowly, so that, if possible, I may keep in a somewhat better state of health. I had not thought of illustrations; that is capital advice. Farewell, my good and admirable agent for the promulgation of damnable heresies! LETTER 86. TO L. HORNER. Down, December 23rd [1859]. I must have the pleasure of thanking you for your extremely kind letter. I am very much pleased that you approve of my book, and that you are going to pay me the extraordinary compliment of reading it twice. I fear that it is tough reading, but it is beyond my powers to make the subject clearer. Lyell would have done it admirably. You must enjoy being a gentlemen at your ease, and I hear that you have returned with ardour to work at the Geological Society. We hope in the course of the winter to persuade Mrs. Horner and yourself and daughters to pay us a visit. Ilkley did me extraordinary good during the latter part of my stay and during my first week at home; but I have gone back latterly to my bad ways, and fear I shall never be decently well and strong. P.S.--When any of your party write to Mildenhall I should be much obliged if you would say to Bunbury that I hope he will not forget, whenever he reads my book, his promise to let me know what he thinks about it; for his knowledge is so great and accurate that every one must value his opinions highly. I shall be quite contented if his belief in the immutability of species is at all staggered. LETTER 87. TO C. LYELL. (87/1. In the "Origin of Species" a section of Chapter X. is devoted to "The succession of the same types within the same areas, during the late Tertiary period" (Edition I., page 339). Mr. Darwin wrote as follows: "Mr. Clift many years ago showed that the fossil mammals from the Australian caves were closely allied to the living marsupials of that continent." After citing other instances illustrating the same agreement between fossil and recent types, Mr. Darwin continues: "I was so much impressed with these facts that I strongly insisted, in 1839 and 1845, on this 'law of the succession of types,' on 'this wonderful relationship in the same continent between the dead and the living.' Professor Owen has subsequently extended the same generalisation to the mammals of the Old World.") Down, [December] 27th [1859]. Owen wrote to me to ask for the reference to Clift. As my own notes for the late chapters are all in chaos, I bethought me who was the most trustworthy man of all others to look for references, and I answered myself, "Of course Lyell." In the ["Principles of Geology"], edition of 1833, Volume III., chapter xi., page 144, you will find the reference to Clift in the "Edinburgh New Phil Journal," No. XX., page 394. (87/2. The correct reference to Clift's "Report" on fossil bones from New Holland is "Edinburgh New Phil. Journal," 1831, page 394.) You will also find that you were greatly struck with the fact itself (87/3. This refers to the discovery of recent and fossil species of animals in an Australian cave-breccia. Mr. Clift is quoted as having identified one of the bones, which was much larger than the rest, as that of a hippopotamus.), which I had quite forgotten. I copied the passage, and sent it to Owen. Why I gave in some detail references to my own work is that Owen (not the first occasion with respect to myself and others) quietly ignores my having ever generalised on the subject, and makes a great fuss on more than one occasion at having discovered the law of succession. In fact, this law, with the Galapagos distribution, first turned my mind on the origin of species. My own references are [to the "Naturalist's Voyage"]: Large 8vo, Murray, Edition 1839 Edition 1845 Page 210 Page 173 On succession. Page 153 Pages 131-32 On splitting up of old geographical provinces. Long before Owen published I had in MS. worked out the succession of types in the Old World (as I remember telling Sedgwick, who of course disbelieved it). Since receiving your last letter on Hooker, I have read his introduction as far as page xxiv (87/4. "On the Flora of Australia, etc.; being an Introductory Essay to the Flora of Tasmania": London, 1859.), where the Australian flora begins, and this latter part I liked most in the proofs. It is a magnificent essay. I doubt slightly about some assertions, or rather should have liked more facts--as, for instance, in regard to species varying most on the confines of their range. Naturally I doubt a little his remarks about divergence (87/5. "Variation is effected by graduated changes; and the tendency of varieties, both in nature and under cultivation, when further varying, is rather to depart more and more widely from the original type than to revert to it." On the margin Darwin wrote: "Without selection doubtful" (loc. cit., page viii).), and about domestic races being produced under nature without selection. It would take much to persuade me that a Pouter Pigeon, or a Carrier, etc., could have been produced by the mere laws of variation without long continued selection, though each little enlargement of crop and beak are due to variation. I demur greatly to his comparison of the products of sinking and rising islands (87/6. "I venture to anticipate that a study of the vegetation of the islands with reference to the peculiarities of the generic types on the one hand, and of the geological conditions (whether as rising or sinking) on the other, may, in the present state of our knowledge, advance other subjects of distribution and variation considerably" (loc. cit., page xv).); in the Indian Ocean he compares exclusively many rising volcanic and sinking coral islands. The latter have a most peculiar soil, and are excessively small in area, and are tenanted by very few species; moreover, such low coral islands have probably been often, during their subsidence, utterly submerged, and restocked by plants from other islands. In the Pacific Ocean the floras of all the best cases are unknown. The comparison ought to have been exclusively between rising and fringed volcanic islands, and sinking and encircled volcanic islands. I have read Naudin (87/7. Naudin, "Revue Horticole," 1852?.), and Hooker agrees that he does not even touch on my views. LETTER 88. J.D. HOOKER TO CHARLES DARWIN. [1859 or 1860.] I have had another talk with Bentham, who is greatly agitated by your book: evidently the stern, keen intellect is aroused, and he finds that it is too late to halt between two opinions. How it will go we shall see. I am intensely interested in what we shall come to, and never broach the subject to him. I finished the geological evidence chapters yesterday; they are very fine and very striking, but I cannot see they are such forcible objections as you still hold them to be. I would say that you still in your secret soul underrate the imperfection of the Geological Record, though no language can be stronger or arguments fairer and sounder against it. Of course I am influenced by Botany, and the conviction that we have not in a fossilised condition a fraction of the plants that have existed, and that not a fraction of those we have are recognisable specifically. I never saw so clearly put the fact that it is not intermediates between existing species we want, but between these and the unknown tertium quid. You certainly make a hobby of Natural Selection, and probably ride it too hard; that is a necessity of your case. If the improvement of the creation-by-variation doctrine is conceivable, it will be by unburthening your theory of Natural Selection, which at first sight seems overstrained--i.e., to account for too much. I think, too, that some of your difficulties which you override by Natural Selection may give way before other explanations. But, oh Lord! how little we do know and have known to be so advanced in knowledge by one theory. If we thought ourselves knowing dogs before you revealed Natural Selection, what d--d ignorant ones we must surely be now we do know that law. I hear you may be at the Club on Thursday. I hope so. Huxley will not be there, so do not come on that ground. LETTER 89. TO T.H. HUXLEY. January 1st [1860]. I write one line merely to thank you for your pleasant note, and to say that I will keep your secret. I will shake my head as mysteriously as Lord Burleigh. Several persons have asked me who wrote that "most remarkable article" in the "Times." (89/1. The "Times," December 26th, 1859, page 8. The opening paragraphs were by one of the staff of the "Times." See "Life and Letters," II., page 255, for Mr. Huxley's interesting account of his share in the matter.) As a cat may look at a king, so I have said that I strongly suspected you. X was so sharp that the first sentence revealed the authorship. The Z's (God save the mark) thought it was Owen's! You may rely on it that it has made a deep impression, and I am heartily glad that the subject and I owe you this further obligation. But for God's sake, take care of your health; remember that the brain takes years to rest, whilst the muscles take only hours. There is poor Dana, to whom I used to preach by letter, writes to me that my prophecies are come true: he is in Florence quite done up, can read nothing and write nothing, and cannot talk for half an hour. I noticed the "naughty sentence" (89/2. Mr. Huxley, after speaking of the rudimental teeth of the whale, of rudimental jaws in insects which never bite, and rudimental eyes in blind animals, goes on: "And we would remind those who, ignorant of the facts, must be moved by authority, that no one has asserted the incompetence of the doctrine of final causes, in its application to physiology and anatomy, more strongly than our own eminent anatomist, Professor Owen, who, speaking of such cases, says ("On the Nature of Limbs," pages 39, 40), 'I think it will be obvious that the principle of final adaptations fails to satisfy all the conditions of the problem.'"--"The Times," December 26th, 1859.) about Owen, though my wife saw its bearing first. Farewell you best and worst of men! That sentence about the bird and the fish dinners charmed us. Lyell wrote to me--style like yours. Have you seen the slashing article of December 26th in the "Daily News," against my stealing from my "master," the author of the "Vestiges?" LETTER 90. TO J.L.A. DE QUATREFAGES. [Undated] How I should like to know whether Milne Edwards has read the copy which I sent him, and whether he thinks I have made a pretty good case on our side of the question. There is no naturalist in the world for whose opinion I have so profound a respect. Of course I am not so silly as to expect to change his opinion. LETTER 91. TO C. LYELL. (91/1. The date of this letter is doubtful; but as it evidently refers to the 2nd edition of the "Origin," which appeared on January 7th, 1860, we believe that December 9th, 1859, is right. The letter of Sedgwick's is doubtless that given in the "Life and Letters," II., page 247; it is there dated December 24th, 1859, but from other evidence it was probably written on November 24th) [December?] 9th [1859]. I send Sedgwick's letter; it is terribly muddled, and really the first page seems almost childish. I am sadly over-worked, so will not write to you. I have worked in a number of your invaluable corrections--indeed, all as far as time permits. I infer from a letter from Huxley that Ramsay (91/2. See a letter to Huxley, November 27th, 1859, "Life and Letters," II., page 282.) is a convert, and I am extremely glad to get pure geologists, as they will be very few. Many thanks for your very pleasant note. What pleasure you have given me. I believe I should have been miserable had it not been for you and a few others, for I hear threatening of attacks which I daresay will be severe enough. But I am sure that I can now bear them. LETTER 92. TO T.H. HUXLEY. (92/1. The point here discussed is one to which Mr. Huxley attached great, in our opinion too great, importance.) Down, January 11th [1860?]. I fully agree that the difficulty is great, and might be made much of by a mere advocate. Will you oblige me by reading again slowly from pages 267 to 272. (92/2. The reference is to the "Origin," Edition I.: the section on "The Fertility of Varieties when crossed, and of their Mongrel Offspring" occupies pages 267-72.) I may add to what is there said, that it seems to me quite hopeless to attempt to explain why varieties are not sterile, until we know the precise cause of sterility in species. Reflect for a moment on how small and on what very peculiar causes the unequal reciprocity of fertility in the same two species must depend. Reflect on the curious case of species more fertile with foreign pollen than their own. Reflect on many cases which could be given, and shall be given in my larger book (independently of hybridity) of very slight changes of conditions causing one species to be quite sterile and not affecting a closely allied species. How profoundly ignorant we are on the intimate relation between conditions of life and impaired fertility in pure species! The only point which I might add to my short discussion on this subject, is that I think it probable that the want of adaptation to uniform conditions of life in our domestic varieties has played an important part in preventing their acquiring sterility when crossed. For the want of uniformity, and changes in the conditions of life, seem the only cause of the elimination of sterility (when crossed) under domestication. (92/3. The meaning which we attach to this obscure sentence is as follows: Species in a state of nature are closely adapted to definite conditions of life, so that the sexual constitution of species A is attuned, as it were, to a condition different from that to which B is attuned, and this leads to sterility. But domestic varieties are not strictly adapted by Natural Selection to definite conditions, and thus have less specialised sexual constitutions.) This elimination, though admitted by many authors, rests on very slight evidence, yet I think is very probably true, as may be inferred from the case of dogs. Under nature it seems improbable that the differences in the reproductive constitution, on which the sterility of any two species when crossed depends, can be acquired directly by Natural Selection; for it is of no advantage to the species. Such differences in reproductive constitution must stand in correlation with some other differences; but how impossible to conjecture what these are! Reflect on the case of the variations of Verbascum, which differ in no other respect whatever besides the fluctuating element of the colour of the flower, and yet it is impossible to resist Gartner's evidence, that this difference in the colour does affect the mutual fertility of the varieties. The whole case seems to me far too mysterious to rest (92/4. The word "rest" seems to be used in place of "to serve as a foundation for.") a valid attack on the theory of modification of species, though, as you say, it offers excellent ground for a mere advocate. I am surprised, considering how ignorant we are on very many points, [that] more weak parts in my book have not as yet been pointed out to me. No doubt many will be. H.C. Watson founds his objection in MS. on there being no limit to infinite diversification of species: I have answered this, I think, satisfactorily, and have sent attack and answer to Lyell and Hooker. If this seems to you a good objection, I would send papers to you. Andrew Murray "disposes of" the whole theory by an ingenious difficulty from the distribution of blind cave insects (92/5. See "Life and Letters, Volume II., page 265. The reference here is to Murray's address before the Botanical Society, Edinburgh. Mr. Darwin seems to have read Murray's views only in a separate copy reprinted from the "Proc. R. Soc. Edin." There is some confusion about the date of the paper; the separate copy is dated January 16th, while in the volume of the "Proc. R. Soc." it is February 20th. In the "Life and Letters," II., page 261 it is erroneously stated that these are two different papers.); but it can, I think, be fairly answered. LETTER 93. TO T.H. HUXLEY. Down, [February] 2nd [1860]. I have had this morning a letter from old Bronn (93/1. See "Life and Letters, II., page 277.) (who, to my astonishment, seems slightly staggered by Natural Selection), and he says a publisher in Stuttgart is willing to publish a translation, and that he, Bronn, will to a certain extent superintend. Have you written to Kolliker? if not, perhaps I had better close with this proposal--what do you think? If you have written, I must wait, and in this case will you kindly let me hear as soon as you hear from Kolliker? My poor dear friend, you will curse the day when you took up the "general agency" line; but really after this I will not give you any more trouble. Do not forget the three tickets for us for your lecture, and the ticket for Baily, the poulterer. Old Bronn has published in the "Year-book for Mineralogy" a notice of the "Origin" (93/2. "Neues Jahrb. fur Min." 1860, page 112.); and says he has himself published elsewhere a foreboding of the theory! LETTER 94. TO J.D. HOOKER. Down, February 14th [1860]. I succeeded in persuading myself for twenty-four hours that Huxley's lecture was a success. (94/1. At the Royal Institution. See "Life and Letters," II., page 282.) Parts were eloquent and good, and all very bold; and I heard strangers say, "What a good lecture!" I told Huxley so; but I demurred much to the time wasted in introductory remarks, especially to his making it appear that sterility was a clear and manifest distinction of species, and to his not having even alluded to the more important parts of the subject. He said that he had much more written out, but time failed. After conversation with others and more reflection, I must confess that as an exposition of the doctrine the lecture seems to me an entire failure. I thank God I did not think so when I saw Huxley; for he spoke so kindly and magnificently of me, that I could hardly have endured to say what I now think. He gave no just idea of Natural Selection. I have always looked at the doctrine of Natural Selection as an hypothesis, which, if it explained several large classes of facts, would deserve to be ranked as a theory deserving acceptance; and this, of course, is my own opinion. But, as Huxley has never alluded to my explanation of classification, morphology, embryology, etc., I thought he was thoroughly dissatisfied with all this part of my book. But to my joy I find it is not so, and that he agrees with my manner of looking at the subject; only that he rates higher than I do the necessity of Natural Selection being shown to be a vera causa always in action. He tells me he is writing a long review in the "Westminster." It was really provoking how he wasted time over the idea of a species as exemplified in the horse, and over Sir J. Hall's old experiment on marble. Murchison was very civil to me over my book after the lecture, in which he was disappointed. I have quite made up my mind to a savage onslaught; but with Lyell, you, and Huxley, I feel confident we are right, and in the long run shall prevail. I do not think Asa Gray has quite done you justice in the beginning of the review of me. (94/2. "Review of Darwin's Theory on the Origin of Species by means of Natural Selection," by "A.G." ("Amer. Jour. Sci." Volume XXIX., page 153, 1860). In a letter to Asa Gray on February 18th, 1860, Darwin writes: "Your review seems to me admirable; by far the best which I have read." ("Life and Letters," II., 1887, page 286.) The review seemed to me very good, but I read it very hastily. LETTER 95. TO C. LYELL. Down, [February] 18th [1860]. I send by this post Asa Gray, which seems to me very good, with the stamp of originality on it. Also Bronn's "Jahrbuch fur Mineralogie." (95/1. See Letter 93.) The united intellect of my family has vainly tried to make it out. I never tried such confoundedly hard german; nor does it seem worth the labour. He sticks to Priestley's Green Matter, and seems to think that till it can be shown how life arises it is no good showing how the forms of life arise. This seems to me about as logical (comparing very great things with little) as to say it was no use in Newton showing the laws of attraction of gravity and the consequent movement of the planets, because he could not show what the attraction of gravity is. The expression "Wahl der Lebens-Weise" (95/2. "Die fruchtbarste und allgemeinste Ursache der Varietaten-Bildung ist jedoch die Wahl der Lebens-Weise" (loc. cit., page 112).) makes me doubt whether B. understands what I mean by Natural Selection, as I have told him. He says (if I understand him) that you ought to be on the same side with me. P.S. Sunday afternoon.--I have kept back this to thank you for your letter, with much news, received this morning. My conscience is uneasy at the time you waste in amusing and interesting me. I was very curious to hear about Phillips. The review in the "Annals" is, as I was convinced, by Wollaston, for I have had a very cordial letter from him this morning. (95/3. A bibliographical Notice "On the Origin of Species by means of Natural Selection; or the Preservation of Favoured Races in the Struggle for Life." ("Annals and Mag." Volume V., pages 132-43, 1860). The notice is not signed. Referring to the article, in a letter to Lyell, February 15th, 1860, Darwin writes: "I am perfectly convinced...that the review in the "Annals" is by Wollaston; no one else in the world would have used so many parentheses" ("Life and Letters," II., page 284).) I send by this post an attack in the "Gardeners' Chronicle" by Harvey (a first-rate botanist, as you probably know). (95/4. In the "Gardeners' Chronicle" of February 18th, 1860, W.H. Harvey described a case of monstrosity in Begonia frigida, which he argued was hostile to the theory of Natural Selection. The passage about Harvey's attack was published in the "Life and Letters," II., page 275.) It seems to me rather strange; he assumes the permanence of monsters, whereas monsters are generally sterile, and not often inheritable. But grant his case, it comes [to this], that I have been too cautious in not admitting great and sudden variations. Here again comes in the mischief of my abstract. In fuller MS. I have discussed the parallel case of a normal fish like a monstrous gold-fish. I end my discussion by doubting, because all cases of monstrosities which resemble normal structures which I could find were not in allied groups. Trees like Aspicarpa (95/5. Aspicarpa, an American genus of Malpighiaceae, is quoted in the "Origin" (Edition VI., page 367) as an illustration of Linnaeus' aphorism that the characters do not give the genus, but the genus gives the characters. During several years' cultivation in France Aspicarpa produced only degraded flowers, which differed in many of the most important points of structure from the proper type of the order; but it was recognised by M. Richard that the genus should be retained among the Malpighiaceae. "This case," adds Darwin, "well illustrates the spirit of our classification."), with flowers of two kinds (in the "Origin"), led me also to speculate on the same subject; but I could find only one doubtfully analogous case of species having flowers like the degraded or monstrous flowers. Harvey does not see that if only a few (as he supposes) of the seedlings inherited being monstrosities, Natural Selection would be necessary to select and preserve them. You had better return the "Gardeners' Chronicle," etc., to my brother's. The case of Begonia (95/6. Harvey's criticism was answered by Sir J.D. Hooker in the following number of the "Gardeners' Chronicle" (February 25th, 1860, page 170).) in itself is very curious; I am tempted to answer the notice, but I will refrain, for there would be no end to answers. With respect to your objection of a multitude of still living simple forms, I have not discussed it anywhere in the "Origin," though I have often thought it over. What you say about progress being only occasional and retrogression not uncommon, I agree to; only that in the animal kingdom I greatly doubt about retrogression being common. I have always put it to myself--What advantage can we see in an infusory animal, or an intestinal worm, or coral polypus, or earthworm being highly developed? If no advantage, they would not become highly developed: not but what all these animals have very complex structures (except infusoria), and they may well be higher than the animals which occupied similar places in the economy of nature before the Silurian epoch. There is a blind snake with the appearances and, in some respects, habits of earthworms; but this blind snake does not tend, as far as we can see, to replace and drive out worms. I think I must in a future edition discuss a few more such points, and will introduce this and H.C. Watson's objection about the infinite number of species and the general rise in organisation. But there is a directly opposite objection to yours which is very difficult to answer--viz. how at the first start of life, when there were only the simplest organisms, how did any complication of organisation profit them? I can only answer that we have not facts enough to guide any speculation on the subject. With respect to Lepidosiren, Ganoid fishes, perhaps Ornithorhynchus, I suspect, as stated in the "Origin," (95/7. "Origin of Species" (Edition VI.), page 83.), that they have been preserved, from inhabiting fresh-water and isolated parts of the world, in which there has been less competition and less rapid progress in Natural Selection, owing to the fewness of individuals which can inhabit small areas; and where there are few individuals variation at most must be slower. There are several allusions to this notion in the "Origin," as under Amblyopsis, the blind cave-fish (95/8. "Origin," page 112.), and under Heer (95/9. "Origin," page 83.) about Madeira plants resembling the fossil and extinct plants of Europe. LETTER 96. TO JAMES LAMONT. Down, March 5th [1860?]. I am much obliged for your long and interesting letter. You have indeed good right to speak confidently about the habits of wild birds and animals; for I should think no one beside yourself has ever sported in Spitzbergen and Southern Africa. It is very curious and interesting that you should have arrived at the conclusion that so-called "Natural Selection" had been efficient in giving their peculiar colours to our grouse. I shall probably use your authority on the similar habits of our grouse and the Norwegian species. I am particularly obliged for your very curious fact of the effect produced by the introduction of the lowland grouse on the wildness of the grouse in your neighbourhood. It is a very striking instance of what crossing will do in affecting the character of a breed. Have you ever seen it stated in any sporting work that game has become wilder in this country? I wish I could get any sort of proof of the fact, for your explanation seems to me equally ingenious and probable. I have myself witnessed in South America a nearly parallel [case] with that which you mention in regard to the reindeer in Spitzbergen, with the Cervus campestris of La Plata. It feared neither man nor the sound of shot of a rifle, but was terrified at the sight of a man on horseback; every one in that country always riding. As you are so great a sportsman, perhaps you will kindly look to one very trifling point for me, as my neighbours here think it too absurd to notice--namely, whether the feet of birds are dirty, whether a few grains of dirt do not adhere occasionally to their feet. I especially want to know how this is in the case of birds like herons and waders, which stalk in the mud. You will guess that this relates to dispersal of seeds, which is one of my greatest difficulties. My health is very indifferent, and I am seldom able to attend the scientific meetings, but I sincerely hope that I may some time have the pleasure of meeting you. Pray accept my cordial thanks for your very kind letter. LETTER 97. TO G.H.K. THWAITES. Down, March 21st [1860]. I thank you very sincerely for your letter, and am much pleased that you go a little way with me. You will think it presumptuous, but I am well convinced from my own mental experience that if you keep the subject at all before your mind you will ultimately go further. The present volume is a mere abstract, and there are great omissions. One main one, which I have rectified in the foreign editions, is an explanation (which has satisfied Lyell, who made the same objection with you) why many forms do not progress or advance (and I quite agree about some retrograding). I have also a MS. discussion on beauty; but do you really suppose that for instance Diatomaceae were created beautiful that man, after millions of generations, should admire them through the microscope? (97/1. Thwaites (1811-82) published several papers on the Diatomaceae ("On Conjugation in the Diatomaceae," "Ann. and Mag. Nat. Hist." Volume XX., 1847, pages 9-11, 343-4; "Further Observations on the Diatomaceae," loc. cit., 1848, page 161). See "Life and Letters" II., page 292.) I should attribute most of such structures to quite unknown laws of growth; and mere repetition of parts is to our eyes one main element of beauty. When any structure is of use (and I can show what curiously minute particulars are often of highest use), I can see with my prejudiced eyes no limit to the perfection of the coadaptations which could be effected by Natural Selection. I rather doubt whether you see how far, as it seems to me, the argument for homology and embryology may be carried. I do not look at this as mere analogy. I would as soon believe that fossil shells were mere mockeries of real shells as that the same bones in the foot of a dog and wing of a bat, or the similar embryo of mammal and bird, had not a direct signification, and that the signification can be unity of descent or nothing. But I venture to repeat how much pleased I am that you go some little way with me. I find a number of naturalists do the same, and as their halting-places are various, and I must think arbitrary, I believe they will all go further. As for changing at once one's opinion, I would not value the opinion of a man who could do so; it must be a slow process. (97/2. Darwin wrote to Woodward in regard to the "Origin": "It may be a vain and silly thing to say, but I believe my book must be read twice carefully to be fully understood. You will perhaps think it by no means worth the labour.") Thank you for telling me about the Lantana (97/3. An exotic species of Lantana (Verbenaceae) grows vigorously in Ceylon, and is described as frequently making its appearance after the firing of the low-country forests (see H.H.W. Pearson, "The Botany of the Ceylon Patanas," "Journal Linn. Soc." Volume XXXIV., page 317, 1899). No doubt Thwaites' letter to Darwin referred to the spreading of the introduced Lantana, comparable to that of the cardoon in La Plata and of other plants mentioned by Darwin in the "Origin of Species" (Edition VI., page 51).), and I should at any time be most grateful for any information which you think would be of use to me. I hope that you will publish a list of all naturalised plants in Ceylon, as far as known, carefully distinguishing those confined to cultivated soils alone. I feel sure that this most important subject has been greatly undervalued. LETTER 98. TO T.H. HUXLEY. (98/1. The reference here is to the review on the "Origin of Species" generally believed to be by the late Sir R. Owen, and published in the April number of the "Edinburgh Review," 1860. Owen's biographer is silent on the subject, and prints, without comment, the following passage in an undated letter from Sedgwick to Owen: "Do you know who was the author of the article in the "Edinburgh" on the subject of Darwin's theory? On the whole, I think it very good. I once suspected that you must have had a hand in it, and I then abandoned that thought. I have not read it with any care" (Owen's "Life," Volume II., page 96). April 9th [1860]. I never saw such an amount of misrepresentation. At page 530 (98/2. "Lasting and fruitful conclusions have, indeed, hitherto been based only on the possession of knowledge; now we are called upon to accept an hypothesis on the plea of want of knowledge. The geological record, it is averred, is so imperfect!"--"Edinburgh Review," CXI., 1860, page 530.) he says we are called on to accept the hypothesis on the plea of ignorance, whereas I think I could not have made it clearer that I admit the imperfection of the Geological Record as a great difficulty. The quotation (98/3. "We are appealed to, or at least 'the young and rising naturalists with plastic minds,* [On the Nature of the Limbs, page 482] are adjured." It will be seen that the inverted comma after "naturalists" is omitted; the asterisk referring, in a footnote (here placed in square brackets), to page 482 of the "Origin," seems to have been incorrectly assumed by Mr. Darwin to show the close of the quotation.--Ibid., page 512.) on page 512 of the "Review" about "young and rising naturalists with plastic minds," attributed to "nature of limbs," is a false quotation, as I do not use the words "plastic minds." At page 501 (98/4. The passage ("Origin," Edition I., page 483) begins, "But do they really believe...," and shows clearly that the author considers such a belief all but impossible.) the quotation is garbled, for I only ask whether naturalists believe about elemental atoms flashing, etc., and he changes it into that I state that they do believe. At page 500 (98/5. "All who have brought the transmutation speculation to the test of observed facts and ascertained powers in organic life, and have published the results, usually adverse to such speculations, are set down by Mr. Darwin as 'curiously illustrating the blindness of preconceived opinion.'" The passage in the "Origin," page 482, begins by expressing surprise at the point of view of some naturalists: "They admit that a multitude of forms, which till lately they themselves thought were special creations,...have been produced by variation, but they refuse to extend the same view to other and very slightly different forms...They admit variation as a vera causa in one case, they arbitrarily reject it in another, without assigning any distinction in the two cases. The day will come when this will be given as a curious illustration of the blindness of preconceived opinion.") it is very false to say that I imply by "blindness of preconceived opinion" the simple belief of creation. And so on in other cases. But I beg pardon for troubling you. I am heartily sorry that in your unselfish endeavours to spread what you believe to be truth, you should have incurred so brutal an attack. (98/6. The "Edinburgh" Reviewer, referring to Huxley's Royal Institution Lecture given February 10th, 1860, "On Species and Races and their Origin," says (page 521), "We gazed with amazement at the audacity of the dispenser of the hour's intellectual amusement, who, availing himself of the technical ignorance of the majority of his auditors, sought to blind them as to the frail foundations of 'natural selection' by such illustrations as the subjoined": And then follows a critique of the lecturer's comparison of the supposed descent of the horse from the Palaeothere with that of various kinds of domestic pigeons from the Rock-pigeon.) And now I will not think any more of this false and malignant attack. LETTER 99. TO MAXWELL MASTERS. Down, April 13th [1860]. I thank you very sincerely for your two kind notes. The next time you write to your father I beg you to give him from me my best thanks, but I am sorry that he should have had the trouble of writing when ill. I have been much interested by the facts given by him. If you think he would in the least care to hear the result of an artificial cross of two sweet peas, you can send the enclosed; if it will only trouble him, tear it up. There seems to be so much parallelism in the kind of variation from my experiment, which was certainly a cross, and what Mr. Masters has observed, that I cannot help suspecting that his peas were crossed by bees, which I have seen well dusted with the pollen of the sweet pea; but then I wish this, and how hard it is to prevent one's wish biassing one's judgment! I was struck with your remark about the Compositae, etc. I do not see that it bears much against me, and whether it does or not is of course of not the slightest importance. Although I fully agree that no definition can be drawn between monstrosities and slight variations (such as my theory requires), yet I suspect there is some distinction. Some facts lead me to think that monstrosities supervene generally at an early age; and after attending to the subject I have great doubts whether species in a state of nature ever become modified by such sudden jumps as would result from the Natural Selection of monstrosities. You cannot do me a greater service than by pointing out errors. I sincerely hope that your work on monstrosities (99/1. "Vegetable Teratology," London, 1869 (Ray Soc.).) will soon appear, for I am sure it will be highly instructive. Now for your notes, for which let me again thank you. 1. Your conclusion about parts developed (99/2. See "Origin of Species," Edition I., page 153, on the variability of parts "developed in an extraordinary manner in any one species, compared with the other species of the same genus." See "Life and Letters," II., pages 97, 98, also Letter 33.) not being extra variable agrees with Hooker's. You will see that I have stated that the rule apparently does not hold with plants, though it ought, if true, to hold good with them. 2. I cannot now remember in what work I saw the statement about Peloria affecting the axis, but I know it was one which I thought might be trusted. I consulted also Dr. Falconer, and I think that he agreed to the truth of it; but I cannot now tell where to look for my notes. I had been much struck with finding a Laburnum tree with the terminal flowers alone in each raceme peloric, though not perfectly regular. The Pelargonium case in the "Origin" seems to point in the same direction. (99/3. "Origin of Species," Edition I., page 145.) 3. Thanks for the correction about furze: I found the seedlings just sprouting, and was so much surprised and their appearance that I sent them to Hooker; but I never plainly asked myself whether they were cotyledons or first leaves. (99/4. The trifoliate leaves of furze seedlings are not cotyledons, but early leaves: see Lubbock's "Seedlings," I., page 410.) 4. That is a curious fact about the seeds of the furze, the more curious as I found with Leguminosae that immersion in plain cold water for a very few days killed some kinds. If at any time anything should occur to you illustrating or opposing my notions, and you have leisure to inform me, I should be truly grateful, for I can plainly see that you have wealth of knowledge. With respect to advancement or retrogression in organisation in monstrosities of the Compositae, etc., do you not find it very difficult to define which is which? Anyhow, most botanists seem to differ as widely as possible on this head. LETTER 100. TO J.S. HENSLOW. Down, May 8th [1860]. Very many thanks about the Elodea, which case interests me much. I wrote to Mr. Marshall (100/1. W. Marshall was the author of "Anacharis alsinastrum, a new water-weed": four letters to the "Cambridge Independent Press," reprinted as a pamphlet, 1852.) at Ely, and in due time he says he will send me whatever information he can procure. Owen is indeed very spiteful. (100/2. Owen was believed to be the author of the article in the "Edinburgh Review," April, 1860. See Letter 98.) He misrepresents and alters what I say very unfairly. But I think his conduct towards Hooker most ungenerous: viz., to allude to his essay (Australian Flora), and not to notice the magnificent results on geographical distribution. The Londoners say he is mad with envy because my book has been talked about; what a strange man to be envious of a naturalist like myself, immeasurably his inferior! From one conversation with him I really suspect he goes at the bottom of his hidden soul as far as I do. I wonder whether Sedgwick noticed in the "Edinburgh Review" about the "Sacerdotal revilers,"--so the revilers are tearing each other to pieces. I suppose Sedgwick will be very fierce against me at the Philosophical Society. (100/3. The meeting of the "Cambridge Phil. Soc." was held on May 7th, 1860, and fully reported in the "Cambridge Chronicle," May 19th. Sedgwick is reported to have said that "Darwin's theory is not inductive--is not based on a series of acknowledged facts, leading to a general conclusion evolved, logically out of the facts...The only facts he pretends to adduce, as true elements of proof, are the varieties produced by domestication and the artifices of crossbreeding." Sedgwick went on to speak of the vexatious multiplication of supposed species, and adds, "In this respect Darwin's theory may help to simplify our classifications, and thereby do good service to modern science. But he has not undermined any grand truth in the constancy of natural laws, and the continuity of true species.") Judging from his notice in the "Spectator," (100/4. March 24th, 1860; see "Life and Letters," II., page 297.) he will misrepresent me, but it will certainly be unintentionally done. In a letter to me, and in the above notice, he talks much about my departing from the spirit of inductive philosophy. I wish, if you ever talk on the subject to him, you would ask him whether it was not allowable (and a great step) to invent the undulatory theory of light, i.e. hypothetical undulations, in a hypothetical substance, the ether. And if this be so, why may I not invent the hypothesis of Natural Selection (which from the analogy of domestic productions, and from what we know of the struggle for existence and of the variability of organic beings, is, in some very slight degree, in itself probable) and try whether this hypothesis of Natural Selection does not explain (as I think it does) a large number of facts in geographical distribution--geological succession, classification, morphology, embryology, etc. I should really much like to know why such an hypothesis as the undulation of the ether may be invented, and why I may not invent (not that I did invent it, for I was led to it by studying domestic varieties) any hypothesis, such as Natural Selection. Pray forgive me and my pen for running away with me, and scribbling on at such length. I can perfectly understand Sedgwick (100/5. See "Life and Letters," II., page 247; the letter is there dated December 24th, but must, we think, have been written in November at latest.) or any one saying that Natural Selection does not explain large classes of facts; but that is very different from saying that I depart from right principles of scientific investigation. LETTER 101. TO J.S. HENSLOW. Down, May 14th [1860]. I have been greatly interested by your letter to Hooker, and I must thank you from my heart for so generously defending me, as far as you could, against my powerful attackers. Nothing which persons say hurts me for long, for I have an entire conviction that I have not been influenced by bad feelings in the conclusions at which I have arrived. Nor have I published my conclusions without long deliberation, and they were arrived at after far more study than the public will ever know of, or believe in. I am certain to have erred in many points, but I do not believe so much as Sedgwick and Co. think. Is there any Abstract or Proceedings of the Cambridge Philosophical Society published? (101/1. Henslow's remarks are not given in the above-mentioned report in the "Cambridge Chronicle.") If so, and you could get me a copy, I should like to have one. Believe me, my dear Henslow, I feel grateful to you on this occasion, and for the multitude of kindnesses you have done me from my earliest days at Cambridge. LETTER 102. TO C. LYELL. Down, May 22nd [1860]. Hooker has sent me a letter of Thwaites (102/1. See Letter 97.), of Ceylon, who makes exactly the same objections which you did at first about the necessity of all forms advancing, and therefore the difficulty of simple forms still existing. There was no worse omission than this in my book, and I had the discussion all ready. I am extremely glad to hear that you intend adding new arguments about the imperfection of the Geological Record. I always feel this acutely, and am surprised that such men as Ramsay and Jukes do not feel it more. I quite agree on insufficient evidence about mummy wheat. (102/2. See notes appended to a letter to Lyell, September 1843 (Botany). When you can spare it, I should like (but out of mere curiosity) to see Binney on Coal marine marshes. I once made Hooker very savage by saying that I believed the Coal plants grew in the sea, like mangroves. (102/3. See "Life and Letters," I., page 356.) LETTER 103. TO J.D. HOOKER. (103/1. This letter is of interest as containing a strong expression upon the overwhelming importance of selection.) Down [1860]. Many thanks for Harvey's letter (103/2. W.H. Harvey had been corresponding with Sir J.D. Hooker on the "Origin of Species."), which I will keep a little longer and then return. I will write to him and try to make clear from analogy of domestic productions the part which I believe selection has played. I have been reworking my pigeons and other domestic animals, and I am sure that any one is right in saying that selection is the efficient cause, though, as you truly say, variation is the base of all. Why I do not believe so much as you do in physical agencies is that I see in almost every organism (though far more clearly in animals than in plants) adaptation, and this except in rare instances, must, I should think, be due to selection. Do not forget the Pyrola when in flower. (103/3. In a letter to Hooker, May 22nd, 1860, Darwin wrote: "Have you Pyrola at Kew? if so, for heaven's sake observe the curvature of the pistil towards the gangway to the nectary." The fact of the stigma in insect-visited flowers being so placed that the visitor must touch it on its way to the nectar, was a point which early attracted Darwin's attention and strongly impressed him.) My blessed little Scaevola has come into flower, and I will try artificial fertilisation on it. I have looked over Harvey's letter, and have assumed (I hope rightly) that he could not object to knowing that you had forwarded it to me. LETTER 104. TO ASA GRAY. Down, June 8th [1860]. I have to thank you for two notes, one through Hooker, and one with some letters to be posted, which was done. I anticipated your request by making a few remarks on Owen's review. (104/1. "The Edinburgh Review," April, 1860.) Hooker is so weary of reviews that I do not think you will get any hints from him. I have lately had many more "kicks than halfpence." A review in the last Dublin "Nat. Hist. Review" is the most unfair thing which has appeared,--one mass of misrepresentation. It is evidently by Haughton, the geologist, chemist and mathematician. It shows immeasurable conceit and contempt of all who are not mathematicians. He discusses bees' cells, and puts a series which I have never alluded to, and wholly ignores the intermediate comb of Melipona, which alone led me to my notions. The article is a curiosity of unfairness and arrogance; but, as he sneers at Malthus, I am content, for it is clear he cannot reason. He is a friend of Harvey, with whom I have had some correspondence. Your article has clearly, as he admits, influenced him. He admits to a certain extent Natural Selection, yet I am sure does not understand me. It is strange that very few do, and I am become quite convinced that I must be an extremely bad explainer. To recur for a moment to Owen: he grossly misrepresents and is very unfair to Huxley. You say that you think the article must be by a pupil of Owen; but no one fact tells so strongly against Owen, considering his former position at the College of Surgeons, as that he has never reared one pupil or follower. In the number just out of "Fraser's Magazine" (104/2. See "Life and Letters," II., page 314.) there is an article or review on Lamarck and me by W. Hopkins, the mathematician, who, like Haughton, despises the reasoning power of all naturalists. Personally he is extremely kind towards me; but he evidently in the following number means to blow me into atoms. He does not in the least appreciate the difference in my views and Lamarck's, as explaining adaptation, the principle of divergence, the increase of dominant groups, and the almost necessary extinction of the less dominant and smaller groups, etc. LETTER 105. TO C. LYELL. Down, June 17th [1860]. One word more upon the Deification (105/1. "If we confound 'Variation' or 'Natural Selection' with such creational laws, we deify secondary causes or immeasurably exaggerate their influence" (Lyell, "The Geological Evidences of the Antiquity of Man, with Remarks on Theories on the Origin of Species by Variation," page 469, London, 1863). See Letter 131.) of Natural Selection: attributing so much weight to it does not exclude still more general laws, i.e. the ordering of the whole universe. I have said that Natural Selection is to the structure of organised beings what the human architect is to a building. The very existence of the human architect shows the existence of more general laws; but no one, in giving credit for a building to the human architect, thinks it necessary to refer to the laws by which man has appeared. No astronomer, in showing how the movements of planets are due to gravity, thinks it necessary to say that the law of gravity was designed that the planets should pursue the courses which they pursue. I cannot believe that there is a bit more interference by the Creator in the construction of each species than in the course of the planets. It is only owing to Paley and Co., I believe, that this more special interference is thought necessary with living bodies. But we shall never agree, so do not trouble yourself to answer. I should think your remarks were very just about mathematicians not being better enabled to judge of probabilities than other men of common-sense. I have just got more returns about the gestation of hounds. The period differs at least from sixty-one to seventy-four days, just as I expected. I was thinking of sending the "Gardeners' Chronicle" to you, on account of a paper by me on the fertilisation of orchids by insects (105/2. "Fertilisation of British Orchids by Insect Agency." This article in the "Gardeners' Chronicle" of June 9th, 1860, page 528, begins with a request that observations should be made on the manner of fertilisation in the bee-and in the fly-orchis.), as it involves a curious point, and as you cared about my paper on kidney beans; but as you are so busy, I will not. LETTER 106. TO C. LYELL. Down [June?] 20th [1860]. I send Blyth (106/1. See Letter 27.); it is a dreadful handwriting; the passage is on page 4. In a former note he told me he feared there was hardly a chance of getting money for the Chinese expedition, and spoke of your kindness. Many thanks for your long and interesting letter. I wonder at, admire, and thank you for your patience in writing so much. I rather demur to Deinosaurus not having "free will," as surely we have. I demur also to your putting Huxley's "force and matter" in the same category with Natural Selection. The latter may, of course, be quite a false view; but surely it is not getting beyond our depth to first causes. It is truly very remarkable that the gestation of hounds (106/2. In a letter written to Lyell on June 25th, 1860, the following paragraph occurs: "You need not believe one word of what I said about gestation of dogs. Since writing to you I have had more correspondence with the master of hounds, and I see his [record?] is worth nothing. It may, of course, be correct, but cannot be trusted. I find also different statements about the wolf: in fact, I am all abroad.") should vary so much, while that of man does not. It may be from multiple origin. The eggs from the Musk and the common duck take an intermediate period in hatching; but I should rather look at it as one of the ten thousand cases which we cannot explain--namely, when one part or function varies in one species and not in another. Hooker has told me nothing about his explanation of few Arctic forms; I knew the fact before. I had speculated on what I presume, from what you say, is his explanation (106/3. "Outlines of the Distribution of Arctic Plants," J.D. Hooker, "Trans. Linn. Soc." Volume XXIII., page 251, 1862. [read June 21st, 1860.] In this paper Hooker draws attention to the exceptional character of the Greenland flora; but as regards the paucity of its species and in its much greater resemblance to the floras of Arctic Europe than to those of Arctic America, he considers it difficult to account for these facts, "unless we admit Mr. Darwin's hypotheses" (see "Origin," Edition VI., 1872, Chapter XII., page 330) of a southern migration due to the cold of the glacial period and the subsequent return of the northern types during the succeeding warmer period. Many of the Greenland species, being confined to the peninsula, "would, as it were, be driven into the sea--that is exterminated" (Hooker, op. cit., pages 253-4).); but there must have been at all times an Arctic region. I found the speculation got too complex, as it seemed to me, to be worth following out. I have been doing some more interesting work with orchids. Talk of adaptation in woodpeckers (106/4. "Can a more striking instance of adaptation be given than that of a woodpecker for climbing trees and seizing insects in the chinks of the bark?" (Origin of Species," Edition HAVE I., page 141).), some of the orchids beat it. I showed the case to Elizabeth Wedgwood, and her remark was, "Now you have upset your own book, for you won't persuade me that this could be effected by Natural Selection." LETTER 107. TO T.H. HUXLEY. July 20th [1860]. Many thanks for your pleasant letter. I agree to every word you say about "Fraser" and the "Quarterly." (107/1. Bishop Wilberforce's review of the "Origin" in the "Quarterly Review," July, 1860, was republished in his "Collected Essays," 1874. See "Life and Letters, II., page 182, and II., page 324, where some quotations from the review are given. For Hopkins' review in "Fraser's Magazine," June, 1860, see "Life and Letters," II., 314.) I have had some really admirable letters from Hopkins. I do not suppose he has ever troubled his head about geographical distribution, classification, morphologies, etc., and it is only those who have that will feel any relief in having some sort of rational explanation of such facts. Is it not grand the way in which the Bishop asserts that all such facts are explained by ideas in God's mind? The "Quarterly" is uncommonly clever; and I chuckled much at the way my grandfather and self are quizzed. I could here and there see Owen's hand. By the way, how comes it that you were not attacked? Does Owen begin to find it more prudent to leave you alone? I would give five shillings to know what tremendous blunder the Bishop made; for I see that a page has been cancelled and a new page gummed in. I am indeed most thoroughly contented with the progress of opinion. From all that I hear from several quarters, it seems that Oxford did the subject great good. (107/2. An account of the meeting of the British Association at Oxford in 1860 is given in the "Life and Letters," II., page 320, and a fuller account in the one-volume "Life of Charles Darwin," 1892, page 236. See also the "Life and Letters of T.H. Huxley," Volume I., page 179, and the amusing account of the meeting in Mr. Tuckwell's "Reminiscences of Oxford," London, 1900, page 50.) It is of enormous importance the showing the world that a few first-rate men are not afraid of expressing their opinion. I see daily more and more plainly that my unaided book would have done absolutely nothing. Asa Gray is fighting admirably in the United States. He is thorough master of the subject, which cannot be said by any means of such men as even Hopkins. I have been thinking over what you allude to about a natural history review. (107/3. In the "Life and Letters of T.H. Huxley," Volume I., page 209, some account of the founding of the "Natural History Review" is given in a letter to Sir J.D. Hooker of July 17th, 1860. On August 2nd Mr. Huxley added: "Darwin wrote me a very kind expostulation about it, telling me I ought not to waste myself on other than original work. In reply, however, I assured him that I MUST waste myself willy-nilly, and that the 'Review' was only a save-all.") I suppose you mean really a REVIEW and not journal for original communications in Natural History. Of the latter there is now superabundance. With respect to a good review, there can be no doubt of its value and utility; nevertheless, if not too late, I hope you will consider deliberately before you decide. Remember what a deal of work you have on your shoulders, and though you can do much, yet there is a limit to even the hardest worker's power of working. I should deeply regret to see you sacrificing much time which could be given to original research. I fear, to one who can review as well as you do, there would be the same temptation to waste time, as there notoriously is for those who can speak well. A review is only temporary; your work should be perennial. I know well that you may say that unless good men will review there will be no good reviews. And this is true. Would you not do more good by an occasional review in some well-established review, than by giving up much time to the editing, or largely aiding, if not editing, a review which from being confined to one subject would not have a very large circulation? But I must return to the chief idea which strikes me--viz., that it would lessen the amount of original and perennial work which you could do. Reflect how few men there are in England who can do original work in the several lines in which you are excellently fitted. Lyell, I remember, on analogous grounds many years ago resolved he would write no more reviews. I am an old slowcoach, and your scheme makes me tremble. God knows in one sense I am about the last man in England who ought to throw cold water on any review in which you would be concerned, as I have so immensely profited by your labours in this line. With respect to reviewing myself, I never tried: any work of that kind stops me doing anything else, as I cannot possibly work at odds and ends of time. I have, moreover, an insane hatred of stopping my regular current of work. I have now materials for a little paper or two, but I know I shall never work them up. So I will not promise to help; though not to help, if I could, would make me feel very ungrateful to you. You have no idea during how short a time daily I am able to work. If I had any regular duties, like you and Hooker, I should do absolutely nothing in science. I am heartily glad to hear that you are better; but how such labour as volunteer-soldiering (all honour to you) does not kill you, I cannot understand. For God's sake remember that your field of labour is original research in the highest and most difficult branches of Natural History. Not that I wish to underrate the importance of clever and solid reviews. LETTER 108. TO T.H. HUXLEY. Sudbrook Park, Richmond, Thursday [July, 1860]. I must send you a line to say what a good fellow you are to send me so long an account of the Oxford doings. I have read it twice, and sent it to my wife, and when I get home shall read it again: it has so much interested me. But how durst you attack a live bishop in that fashion? I am quite ashamed of you! Have you no reverence for fine lawn sleeves? By Jove, you seem to have done it well. If any one were to ridicule any belief of the bishop's, would he not blandly shrug his shoulders and be inexpressibly shocked? I am very, very sorry to hear that you are not well; but am not surprised after all your self-imposed labour. I hope you will soon have an outing, and that will do you real good. I am glad to hear about J. Lubbock, whom I hope to see soon, and shall tell him what you have said. Have you read Hopkins in the last "Fraser?"--well put, in good spirit, except soul discussion bad, as I have told him; nothing actually new, takes the weak points alone, and leaves out all other considerations. I heard from Asa Gray yesterday; he goes on fighting like a Trojan. God bless you!--get well, be idle, and always reverence a bishop. LETTER 109. TO J.D. DANA. Down, July 30th [1860]. I received several weeks ago your note telling me that you could not visit England, which I sincerely regretted, as I should most heartily have liked to have made your personal acquaintance. You gave me an improved, but not very good, account of your health. I should at some time be grateful for a line to tell me how you are. We have had a miserable summer, owing to a terribly long and severe illness of my eldest girl, who improves slightly but is still in a precarious condition. I have been able to do nothing in science of late. My kind friend Asa Gray often writes to me and tells me of the warm discussions on the "Origin of Species" in the United States. Whenever you are strong enough to read it, I know you will be dead against me, but I know equally well that your opposition will be liberal and philosophical. And this is a good deal more than I can say of all my opponents in this country. I have not yet seen Agassiz's attack (109/1. "Silliman's Journal," July, 1860. A passage from Agassiz's review is given by Mr. Huxley in Darwin's "Life and Letters," II., page 184.), but I hope to find it at home when I return in a few days, for I have been for several weeks away from home on my daughter's account. Prof. Silliman sent me an extremely kind message by Asa Gray that your Journal would be open to a reply by me. I cannot decide till I see it, but on principle I have resolved to avoid answering anything, as it consumes much time, often temper, and I have said my say in the "Origin." No one person understands my views and has defended them so well as A. Gray, though he does not by any means go all the way with me. There was much discussion on the subject at the British Association at Oxford, and I had many defenders, and my side seems (for I was not there) almost to have got the best of the battle. Your correspondent and my neighbour, J. Lubbock, goes on working at such spare time as he has. This is an egotistical note, but I have not seen a naturalist for months. Most sincerely and deeply do I hope that this note may find you almost recovered. LETTER 110. TO W.H. HARVEY. (110/1. See Letter 95, note. This letter was written in reply to a long one from W.H. Harvey, dated August 24th, 1860. Harvey had already published a serio-comic squib and a review, to which references are given in the "Life and Letters," II., pages 314 and 375; but apparently he had not before this time completed the reading of the "Origin.") [August, 1860.] I have read your long letter with much interest, and I thank you for your great liberality in sending it me. But, on reflection, I do not wish to attempt answering any part, except to you privately. Anything said by myself in defence would have no weight; it is best to be defended by others, or not at all. Parts of your letter seem to me, if I may be permitted to say so, very acute and original, and I feel it a great compliment your giving up so much time to my book. But, on the whole, I am disappointed; not from your not concurring with me, for I never expected that, and, indeed, in your remarks on Chapters XII. and XIII., you go much further with me (though a little way) than I ever anticipated, and am much pleased at the result. But on the whole I am disappointed, because it seems to me that you do not understand what I mean by Natural Selection, as shown at page 11 (110/2. Harvey speaks of the perpetuation or selection of the useful, pre-supposing "a vigilant and intelligent agent," which is very much like saying that an intelligent agent is needed to see that the small stones pass through the meshes of a sieve and the big ones remain behind.) of your letter and by several of your remarks. As my book has failed to explain my meaning, it would be hopeless to attempt it in a letter. You speak in the early part of your letter, and at page 9, as if I had said that Natural Selection was the sole agency of modification, whereas I have over and over again, ad nauseam, directly said, and by order of precedence implied (what seems to me obvious) that selection can do nothing without previous variability (see pages 80, 108, 127, 468, 469, etc.), "nothing can be effected unless favourable variations occur." I consider Natural Selection as of such high importance, because it accumulates successive variations in any profitable direction, and thus adapts each new being to its complex conditions of life. The term "selection," I see, deceives many persons, though I see no more reason why it should than elective affinity, as used by the old chemists. If I had to rewrite my book, I would use "natural preservation" or "naturally preserved." I should think you would as soon take an emetic as re-read any part of my book; but if you did, and were to erase selection and selected, and insert preservation and preserved, possibly the subject would be clearer. As you are not singular in misunderstanding my book, I should long before this have concluded that my brains were in a haze had I not found by published reviews, and especially by correspondence, that Lyell, Hooker, Asa Gray, H.C. Watson, Huxley, and Carpenter, and many others, perfectly comprehend what I mean. The upshot of your remarks at page 11 is that my explanation, etc., and the whole doctrine of Natural Selection, are mere empty words, signifying the "order of nature." As the above-named clear-headed men, who do comprehend my views, all go a certain length with me, and certainly do not think it all moonshine, I should venture to suggest a little further reflection on your part. I do not mean by this to imply that the opinion of these men is worth much as showing that I am right, but merely as some evidence that I have clearer ideas than you think, otherwise these same men must be even more muddle-headed than I am; for they have no temptation to deceive themselves. In the forthcoming September (110/3. "American Journal of Science and Arts," September 1860, "Design versus Necessity," reprinted in Asa Gray's "Darwiniana," 1876, page 62.) number of the "American Journal of Science" there is an interesting and short theological article (by Asa Gray), which gives incidentally with admirable clearness the theory of Natural Selection, and therefore might be worth your reading. I think that the theological part would interest you. You object to all my illustrations. They are all necessarily conjectural, and may be all false; but they were the best I could give. The bear case (110/4. "Origin of Species," Edition I., page 184. See Letter 120.) has been well laughed at, and disingenuously distorted by some into my saying that a bear could be converted into a whale. As it offended persons, I struck it out in the second edition; but I still maintain that there is no especial difficulty in a bear's mouth being enlarged to any degree useful to its changing habits,--no more difficulty than man has found in increasing the crop of the pigeon, by continued selection, until it is literally as big as the whole rest of the body. If this had not been known, how absurd it would have appeared to say that the crop of a bird might be increased till it became like a balloon! With respect to the ostrich, I believe that the wings have been reduced, and are not in course of development, because the whole structure of a bird is essentially formed for flight; and the ostrich is essentially a bird. You will see at page 182 of the "Origin" a somewhat analogous discussion. At page 450 of the second edition I have pointed out the essential distinction between a nascent and rudimentary organ. If you prefer the more complex view that the progenitor of the ostrich lost its wings, and that the present ostrich is regaining them, I have nothing to say in opposition. With respect to trees on islands, I collected some cases, but took the main facts from Alph. De Candolle, and thought they might be trusted. My explanation may be grossly wrong; but I am not convinced it is so, and I do not see the full force of your argument of certain herbaceous orders having been developed into trees in certain rare cases on continents. The case seems to me to turn altogether on the question whether generally herbaceous orders more frequently afford trees and bushes on islands than on continents, relatively to their areas. (110/5. In the "Origin," Edition I., page 392, the author points out that in the presence of competing trees an herbaceous plant would have little chance of becoming arborescent; but on an island, with only other herbaceous plants as competitors, it might gain an advantage by overtopping its fellows, and become tree-like. Harvey writes: "What you say (page 392) of insular trees belonging to orders which elsewhere include only herbaceous species seems to me to be unsupported by sufficient evidence. You cite no particular trees, and I may therefore be wrong in guessing that the orders you allude to are Scrophularineae and Compositae; and the insular trees the Antarctic Veronicas and the arborescent Compositae of St. Helena, Tasmania, etc. But in South Africa Halleria (Scrophularineae) is often as large and woody as an apple tree; and there are several South African arborescent Compositae (Senecio and Oldenburgia). Besides, in Tasmania at least, the arborescent Composites are not found competing with herbaceous plants alone, and growing taller and taller by overtopping them...; for the most arborescent of them all (Eurybia argophylla, the Musk tree) grows...in Eucalyptus forests. And so of the South African Halleria, which is a tree among trees. What the conditions of the arborescent Gerania of the Sandwich Islands may be I am unable to say...I cannot remember any other instances, nor can I accept your explanation in any other of the cases I have cited.") In page 4 of your letter you say you give up many book-species as separate creations: I give up all, and you infer that our difference is only in degree and not in kind. I dissent from this; for I give a distinct reason how far I go in giving up species. I look at all forms, which resemble each other homologically or embryologically, as certainly descended from the same species. You hit me hard and fairly (110/6. Harvey writes: "You ask--were all the infinitely numerous kinds of animals and plants created as eggs or seed, or as full grown? To this it is sufficient to reply, was your primordial organism, or were your four or five progenitors created as egg, seed, or full grown? Neither theory attempts to solve this riddle, nor yet the riddle of the Omphalos." The latter point, which Mr. Darwin refuses to give up, is at page 483 of the "Origin," "and, in the case of mammals, were they created bearing the false marks of nourishment from the mother's womb?" In the third edition of the "Origin," 1861, page 517, the author adds, after the last-cited passage: "Undoubtedly these same questions cannot be answered by those who, under the present state of science, believe in the creation of a few aboriginal forms, or of some one form of life. In the sixth edition, probably with a view to the umbilicus, he writes (page 423): "Undoubtedly some of these same questions," etc., etc. From notes in Mr. Darwin's copy of the second edition it is clear that the change in the third edition was chiefly due to Harvey's letter. See Letter 115.) about my question (page 483, "Origin") about creation of eggs or young, etc., (but not about mammals with the mark of the umbilical cord), yet I still have an illogical sort of feeling that there is less difficulty in imagining the creation of an asexual cell, increasing by simple division. Page 5 of your letter: I agree to every word about the antiquity of the world, and never saw the case put by any one more strongly or more ably. It makes, however, no more impression on me as an objection than does the astronomer when he puts on a few hundred million miles to the distance of the fixed stars. To compare very small things with great, Lingula, etc., remaining nearly unaltered from the Silurian epoch to the present day, is like the dovecote pigeons still being identical with wild Rock-pigeons, whereas its "fancy" offspring have been immensely modified, and are still being modified, by means of artificial selection. You put the difficulty of the first modification of the first protozoon admirably. I assure you that immediately after the first edition was published this occurred to me, and I thought of inserting it in the second edition. I did not, because we know not in the least what the first germ of life was, nor have we any fact at all to guide us in our speculations on the kind of change which its offspring underwent. I dissent quite from what you say of the myriads of years it would take to people the world with such imagined protozoon. In how very short a time Ehrenberg calculated that a single infusorium might make a cube of rock! A single cube on geometrical progression would make the solid globe in (I suppose) under a century. From what little I know, I cannot help thinking that you underrate the effects of the physical conditions of life on these low organisms. But I fully admit that I can give no sort of answer to your objections; yet I must add that it would be marvellous if any man ever could, assuming for the moment that my theory is true. You beg the question, I think, in saying that Protococcus would be doomed to eternal similarity. Nor can you know that the first germ resembled a Protococcus or any other now living form. Page 12 of your letter: There is nothing in my theory necessitating in each case progression of organisation, though Natural Selection tends in this line, and has generally thus acted. An animal, if it become fitted by selection to live the life, for instance, of a parasite, will generally become degraded. I have much regretted that I did not make this part of the subject clearer. I left out this and many other subjects, which I now see ought to have been introduced. I have inserted a discussion on this subject in the foreign editions. (110/7. In the third Edition a discussion on this point is added in Chapter IV.) In no case will any organic being tend to retrograde, unless such retrogradation be an advantage to its varying offspring; and it is difficult to see how going back to the structure of the unknown supposed original protozoon could ever be an advantage. Page 13 of your letter: I have been more glad to read your discussion on "dominant" forms than any part of your letter. (110/8. Harvey writes: "Viewing organic nature in its widest aspect, I think it is unquestionable that the truly dominant races are not those of high, but those of low organisation"; and goes on to quote the potato disease, etc. In the third edition of the "Origin," page 56, a discussion is introduced defining the author's use of the term "dominant.") I can now see that I have not been cautious enough in confining my definition and meaning. I cannot say that you have altered my views. If Botrytis [Phytophthora] had exterminated the wild potato, a low form would have conquered a high; but I cannot remember that I have ever said (I am sure I never thought) that a low form would never conquer a high. I have expressly alluded to parasites half exterminating game-animals, and to the struggle for life being sometimes between forms as different as possible: for instance, between grasshoppers and herbivorous quadrupeds. Under the many conditions of life which this world affords, any group which is numerous in individuals and species and is widely distributed, may properly be called dominant. I never dreamed of considering that any one group, under all conditions and throughout the world, would be predominant. How could vertebrata be predominant under the conditions of life in which parasitic worms live? What good would their perfected senses and their intellect serve under such conditions? When I have spoken of dominant forms, it has been in relation to the multiplication of new specific forms, and the dominance of any one species has been relative generally to other members of the same group, or at least to beings exposed to similar conditions and coming into competition. But I daresay that I have not in the "Origin" made myself clear, and space has rendered it impossible. But I thank you most sincerely for your valuable remarks, though I do not agree with them. About sudden jumps: I have no objection to them--they would aid me in some cases. All I can say is, that I went into the subject, and found no evidence to make me believe in jumps; and a good deal pointing in the other direction. You will find it difficult (page 14 of your letter) to make a marked line of separation between fertile and infertile crosses. I do not see how the apparently sudden change (for the suddenness of change in a chrysalis is of course largely only apparent) in larvae during their development throws any light on the subject. I wish I could have made this letter better worth sending to you. I have had it copied to save you at least the intolerable trouble of reading my bad handwriting. Again I thank you for your great liberality and kindness in sending me your criticisms, and I heartily wish we were a little nearer in accord; but we must remain content to be as wide asunder as the poles, but without, thank God, any malice or other ill-feeling. LETTER 111. TO T.H. HUXLEY. (111/1. Dr. Asa Gray's articles in the "Atlantic Monthly," July, August, and October, 1860, were published in England as a pamphlet, and form Chapter III. in his "Darwiniana" (1876). See "Life and Letters," II., page 338. The article referred to in the present letter is that in the August number.) Down, September 10th [1860]. I send by this post a review by Asa Gray, so good that I should like you to see it; I must beg for its return. I want to ask, also, your opinion about getting it reprinted in England. I thought of sending it to the Editor of the "Annals and Mag. of Nat. Hist." in which two hostile reviews have appeared (although I suppose the "Annals" have a very poor circulation), and asking them in the spirit of fair play to print this, with Asa Gray's name, which I will take the responsibility of adding. Also, as it is long, I would offer to pay expenses. It is very good, in addition, as bringing in Pictet so largely. (111/2. Pictet (1809-72) wrote a "perfectly fair" review opposed to the "Origin." See "Life and Letters," II., page 297.) Tell me briefly what you think. What an astonishing expedition this is of Hooker's to Syria! God knows whether it is wise. How are you and all yours? I hope you are not working too hard. For Heaven's sake, think that you may become such a beast as I am. How goes on the "Nat. Hist. Review?" Talking of reviews, I damned with a good grace the review in the "Athenaeum" (111/3. Review of "The Glaciers of the Alps" ("Athenaeum," September 1, 1860, page 280).) on Tyndall with a mean, scurvy allusion to you. It is disgraceful about Tyndall,--in fact, doubting his veracity. I am very tired, and hate nearly the whole world. So good-night, and take care of your digestion, which means brain. LETTER 112. TO C. LYELL. 15, Marine Parade, Eastbourne, 26th [September 1860]. It has just occurred to me that I took no notice of your questions on extinction in St. Helena. I am nearly sure that Hooker has information on the extinction of plants (112/1. "Principles of Geology," Volume II. (Edition X., 1868), page 453. Facts are quoted from Hooker illustrating the extermination of plants in St. Helena.), but I cannot remember where I have seen it. One may confidently assume that many insects were exterminated. By the way, I heard lately from Wollaston, who told me that he had just received eminently Madeira and Canary Island insect forms from the Cape of Good Hope, to which trifling distance, if he is logical, he will have to extend his Atlantis! I have just received your letter, and am very much pleased that you approve. But I am utterly disgusted and ashamed about the dingo. I cannot think how I could have misunderstood the paper so grossly. I hope I have not blundered likewise in its co-existence with extinct species: what horrid blundering! I am grieved to hear that you think I must work in the notes in the text; but you are so much better a judge that I will obey. I am sorry that you had the trouble of returning the Dog MS., which I suppose I shall receive to-morrow. I mean to give good woodcuts of all the chief races of pigeons. (112/2. "The Variation of Animals and Plants under Domestication," 1868.) Except the C. oenas (112/3. The Columba oenas of Europe roosts on trees and builds its nest in holes, either in trees or the ground ("Var. of Animals," Volume I., page 183).) (which is partly, indeed almost entirely, a wood pigeon), there is no other rock pigeon with which our domestic pigeon would cross--that is, if several exceedingly close geographical races of C. livia, which hardly any ornithologist looks at as true species, be all grouped under C. livia. (112/4. Columba livia, the Rock-pigeon. "We may conclude with confidence that all the domestic races, notwithstanding their great amount of difference, are descended from the Columba livia, including under this name certain wild races" (op. cit., Volume I., page 223).) I am writing higgledy-piggledy, as I re-read your letter. I thought that my letter had been much wilder than yours. I quite feel the comfort of writing when one may "alter one's speculations the day after." It is beyond my knowledge to weigh ranks of birds and monotremes; in the respiratory and circulatory system and muscular energy I believe birds are ahead of all mammals. I knew that you must have known about New Guinea; but in writing to you I never make myself civil! After treating some half-dozen or dozen domestic animals in the same manner as I treat dogs, I intended to have a chapter of conclusions. But Heaven knows when I shall finish: I get on very slowly. You would be surprised how long it took me to pick out what seemed useful about dogs out of multitudes of details. I see the force of your remark about more isolated races of man in old times, and therefore more in number. It seems to me difficult to weigh probabilities. Perhaps so, if you refer to very slight differences in the races: to make great differences much time would be required, and then, even at the earliest period I should have expected one race to have spread, conquered, and exterminated the others. With respect to Falconer's series of Elephants (112/5. In 1837 Dr. Falconer and Sir Proby Cautley collected a large number of fossil remains from the Siwalik Hills. Falconer and Cautley, "Fauna Antiqua Sivalensis," 1845-49.), I think the case could be answered better than I have done in the "Origin," page 334. (112/6. "Origin of Species," Edition I., page 334. "It is no real objection to the truth of the statement that the fauna of each period as a whole is nearly intermediate in character between the preceding and succeeding faunas, that certain genera offer exceptions to the rule. For instance, mastodons and elephants, when arranged by Dr. Falconer in two series, first according to their mutual affinities and then according to their periods of existence, do not accord in arrangement. The species extreme in character are not the oldest, or the most recent; nor are those which are intermediate in character intermediate in age. But supposing for an instant, in this and other such cases, that the record of the first appearance and disappearance of the species was perfect, we have no reason to believe that forms successively produced necessarily endure for corresponding lengths of time. A very ancient form might occasionally last much longer than a form elsewhere subsequently produced, especially in the case of terrestrial productions inhabiting separated districts" (pages 334-5). The same words occur in the later edition of the "Origin" (Edition VI., page 306.) All these new discoveries show how imperfect the discovered series is, which Falconer thought years ago was nearly perfect. I will send to-day or to-morrow two articles by Asa Gray. The longer one (now not finally corrected) will come out in the October "Atlantic Monthly," and they can be got at Trubner's. Hearty thanks for all your kindness. Do not hurry over Asa Gray. He strikes me as one of the best reasoners and writers I ever read. He knows my book as well as I do myself. LETTER 113. TO C. LYELL. 15, Marine Parade, Eastbourne, October 3rd [1860]. Your last letter has interested me much in many ways. I enclose a letter of Wyman's which touches on brains. Wyman is mistaken in supposing that I did not know that the Cave-rat was an American form; I made special enquiries. He does not know that the eye of the Tucotuco was carefully dissected. With respect to reviews by A. Gray. I thought of sending the Dialogue to the "Saturday Review" in a week's time or so, as they have lately discussed Design. (113/1. "Discussion between two Readers of Darwin's Treatise on the Origin of Species, upon its Natural Theology" ("Amer. Journ. Sci." Volume XXX, page 226, 1860). Reprinted in "Darwiniana," 1876, page 62. The article begins with the following question: "First Reader--Is Darwin's theory atheistic or pantheistic? Or does it tend to atheism or pantheism?" The discussion is closed by the Second Reader, who thus sums up his views: "Wherefore we may insist that, for all that yet appears, the argument for design, as presented by the natural theologians, is just as good now, if we accept Darwin's theory, as it was before the theory was promulgated; and that the sceptical juryman, who was about to join the other eleven in an unanimous verdict in favour of design, finds no good excuse for keeping the Court longer waiting.") I have sent the second, or August, "Atlantic" article to the "Annals and Mag. of Nat. History." (113/2. "Annals and Mag. Nat. Hist." Volume VI., pages 373-86, 1860. (From the "Atlantic Monthly," August, 1860.)) The copy which you have I want to send to Pictet, as I told A. Gray I would, thinking from what he said he would like this to be done. I doubt whether it would be possible to get the October number reprinted in this country; so that I am in no hurry at all for this. I had a letter a few weeks ago from Symonds on the imperfection of the Geological Record, less clear and forcible than I expected. I answered him at length and very civilly, though I could hardly make out what he was driving at. He spoke about you in a way which it did me good to read. I am extremely glad that you like A. Gray's reviews. How generous and unselfish he has been in all his labour! Are you not struck by his metaphors and similes? I have told him he is a poet and not a lawyer. I should altogether doubt on turtles being converted into land tortoises on any one island. Remember how closely similar tortoises are on all continents, as well as islands; they must have all descended from one ancient progenitor, including the gigantic tortoise of the Himalaya. I think you must be cautious in not running the convenient doctrine that only one species out of very many ever varies. Reflect on such cases as the fauna and flora of Europe, North America, and Japan, which are so similar, and yet which have a great majority of their species either specifically distinct, or forming well-marked races. We must in such cases incline to the belief that a multitude of species were once identically the same in all the three countries when under a warmer climate and more in connection; and have varied in all the three countries. I am inclined to believe that almost every species (as we see with nearly all our domestic productions) varies sufficiently for Natural Selection to pick out and accumulate new specific differences, under new organic and inorganic conditions of life, whenever a place is open in the polity of nature. But looking to a long lapse of time and to the whole world, or to large parts of the world, I believe only one or a few species of each large genus ultimately becomes victorious, and leaves modified descendants. To give an imaginary instance: the jay has become modified in the three countries into (I believe) three or four species; but the jay genus is not, apparently, so dominant a group as the crows; and in the long run probably all the jays will be exterminated and be replaced perhaps by some modified crows. I merely give this illustration to show what seems to me probable. But oh! what work there is before we shall understand the genealogy of organic beings! With respect to the Apteryx, I know not enough of anatomy; but ask Dr. F. whether the clavicle, etc., do not give attachment to some of the muscles of respiration. If my views are at all correct, the wing of the Apteryx (113/3. "Origin of Species," Edition VI., page 140.) cannot be (page 452 of the "Origin") a nascent organ, as these wings are useless. I dare not trust to memory, but I know I found the whole sternum always reduced in size in all the fancy and confined pigeons relatively to the same bones in the wild Rock-pigeon: the keel was generally still further reduced relatively to the reduced length of the sternum; but in some breeds it was in a most anomalous manner more prominent. I have got a lot of facts on the reduction of the organs of flight in the pigeon, which took me weeks to work out, and which Huxley thought curious. I am utterly ashamed, and groan over my handwriting. It was "Natural Preservation." Natural persecution is what the author ought to suffer. It rejoices me that you do not object to the term. Hooker made the same remark that it ought to have been "Variation and Natural Selection." Yet with domestic productions, when selection is spoken of, variation is always implied. But I entirely agree with your and Hooker's remark. Have you begun regularly to write your book on the antiquity of man? (113/4. Published in 1863.) I do NOT agree with your remark that I make Natural Selection do too much work. You will perhaps reply that every man rides his hobby-horse to death; and that I am in the galloping state. LETTER 114. TO C. LYELL. 15, Marine Parade, Eastbourne, Friday 5th [October, 1860]. I have two notes to thank you for, and I return Wollaston. It has always seemed to me rather strange that Forbes, Wollaston and Co. should argue, from the presence of allied, and not identical species in islands, for the former continuity of land. They argue, I suppose, from the species being allied in different regions of the same continent, though specifically distinct. But I think one might on the creative doctrine argue with equal force in a directly reverse manner, and say that, as species are so often markedly distinct, yet allied, on islands, all our continents existed as islands first, and their inhabitants were first created on these islands, and since became mingled together, so as not to be so distinct as they now generally are on islands. LETTER 115. TO H.G. BRONN. Down, October 5th [1860]. I ought to apologise for troubling you, but I have at last carefully read your excellent criticisms on my book. (115/1. Bronn added critical remarks to his German translation of the "Origin": see "Life and Letters," II., page 279.) I agree with much of them, and wholly with your final sentence. The objections and difficulties which may be urged against my view are indeed heavy enough almost to break my back, but it is not yet broken! You put very well and very fairly that I can in no one instance explain the course of modification in any particular instance. I could make some sort of answer to your case of the two rats; and might I not turn round and ask him who believes in the separate creation of each species, why one rat has a longer tail or shorter ears than another? I presume that most people would say that these characters were of some use, or stood in some connection with other parts; and if so, Natural Selection would act on them. But as you put the case, it tells well against me. You argue most justly against my question, whether the many species were created as eggs (115/2. See Letter 110.) or as mature, etc. I certainly had no right to ask that question. I fully agree that there might have been as well a hundred thousand creations as eight or ten, or only one. But then, on the view of eight or ten creations (i.e. as many as there are distinct types of structure) we can on my view understand the homological and embryological resemblance of all the organisms of each type, and on this ground almost alone I disbelieve in the innumerable acts of creation. There are only two points on which I think you have misunderstood me. I refer only to one Glacial period as affecting the distribution of organic beings; I did not wish even to allude to the doubtful evidence of glacial action in the Permian and Carboniferous periods. Secondly, I do not believe that the process of development has always been carried on at the same rate in all different parts of the world. Australia is opposed to such belief. The nearly contemporaneous equal development in past periods I attribute to the slow migration of the higher and more dominant forms over the whole world, and not to independent acts of development in different parts. Lastly, permit me to add that I cannot see the force of your objection, that nothing is effected until the origin of life is explained: surely it is worth while to attempt to follow out the action of electricity, though we know not what electricity is. If you should at any time do me the favour of writing to me, I should be very much obliged if you would inform me whether you have yourself examined Brehm's subspecies of birds; for I have looked through some of his writings, but have never met an ornithologist who believed in his [illegible]. Are these subspecies really characteristic of certain different regions of Germany? Should you write, I should much like to know how the German edition sells. LETTER 116. TO J.S. HENSLOW. October 26th [1860]. Many thanks for your note and for all the trouble about the seeds, which will be most useful to me next spring. On my return home I will send the shillings. (116/1. Shillings for the little girls in Henslow's parish who collected seeds for Darwin.) I concluded that Dr. Bree had blundered about the Celts. I care not for his dull, unvarying abuse of me, and singular misrepresentation. But at page 244 he in fact doubts my deliberate word, and that is the act of a man who has not the soul of a gentleman in him. Kingsley is "the celebrated author and divine" (116/2. "Species not Transmutable," by C.R. Bree. After quoting from the "Origin," Edition II., page 481, the words in which a celebrated author and divine confesses that "he has gradually learnt to see that it is just as noble a conception of the Deity to believe that He created a few original forms, etc.," Dr. Bree goes on: "I think we ought to have had the name of this divine given with this remarkable statement. I confess that I have not yet fully made up my mind that any divine could have ever penned lines so fatal to the truths he is called upon to teach.") whose striking sentence I give in the second edition with his permission. I did not choose to ask him to let me use his name, and as he did not volunteer, I had of course no choice. (116/3. We are indebted to Mr. G.W. Prothero for calling our attention to the following striking passage from the works of a divine of this period:--"Just a similar scepticism has been evinced by nearly all the first physiologists of the day, who have joined in rejecting the development theories of Lamarck and the 'Vestiges'...Yet it is now acknowledged under the high sanction of the name of Owen that 'creation' is only another name for our ignorance of the mode of production...while a work has now appeared by a naturalist of the most acknowledged authority, Mr. Darwin's masterly volume on the 'Origin of Species,' by the law of 'natural selection,' which now substantiates on undeniable grounds the very principle so long denounced by the first naturalists--the origination of new species by natural causes: a work which must soon bring about an entire revolution of opinion in favour of the grand principle of the self-evolving powers of nature."--Prof. Baden Powell's "Study of the Evidences of Christianity," "Essays and Reviews," 7th edition, 1861 (pages 138, 139).) Dr. Freke has sent me his paper, which is far beyond my scope--something like the capital quiz in the "Anti-Jacobin" on my grandfather, which was quoted in the "Quarterly Review." LETTER 117. TO D.T. ANSTED. (117/1. The following letter was published in Professor Meldola's presidential address to the Entomological Society, 1897, and to him we are indebted for a copy.) 15, Marine Parade, Eastbourne, October 27th [1860]. As I am away from home on account of my daughter's health, I do not know your address, and fly this at random, and it is of very little consequence if it never reaches you. I have just been reading the greater part of your "Geological Gossip," and have found part very interesting; but I want to express my admiration at the clear and correct manner in which you have given a sketch of Natural Selection. You will think this very slight praise; but I declare that the majority of readers seem utterly incapable of comprehending my long argument. Some of the reviewers, who have servilely stuck to my illustrations and almost to my words, have been correct, but extraordinarily few others have succeeded. I can see plainly, by your new illustrations and manner and order of putting the case, that you thoroughly comprehend the subject. I assure you this is most gratifying to me, and it is the sole way in which the public can be indoctrinated. I am often in despair in making the generality of NATURALISTS even comprehend me. Intelligent men who are not naturalists and have not a bigoted idea of the term species, show more clearness of mind. I think that you have done the subject a real service, and I sincerely thank you. No doubt there will be much error found in my book, but I have great confidence that the main view will be, in time, found correct; for I find, without exception, that those naturalists who went at first one inch with me now go a foot or yard with me. This note obviously requires no answer. LETTER 118. TO H.W. BATES. Down, November 22nd [1860]. I thank you sincerely for writing to me and for your very interesting letter. Your name has for very long been familiar to me, and I have heard of your zealous exertions in the cause of Natural History. But I did not know that you had worked with high philosophical questions before your mind. I have an old belief that a good observer really means a good theorist (118/1. For an opposite opinion, see Letter 13.), and I fully expect to find your observations most valuable. I am very sorry to hear that your health is shattered; but I trust under a healthy climate it may be restored. I can sympathise with you fully on this score, for I have had bad health for many years, and fear I shall ever remain a confirmed invalid. I am delighted to hear that you, with all your large practical knowledge of Natural History, anticipated me in many respects and concur with me. As you say, I have been thoroughly well attacked and reviled (especially by entomologists--Westwood, Wollaston, and A. Murray have all reviewed and sneered at me to their hearts' content), but I care nothing about their attacks; several really good judges go a long way with me, and I observe that all those who go some little way tend to go somewhat further. What a fine philosophical mind your friend Mr. Wallace has, and he has acted, in relation to me, like a true man with a noble spirit. I see by your letter that you have grappled with several of the most difficult problems, as it seems to me, in Natural History--such as the distinctions between the different kinds of varieties, representative species, etc. Perhaps I shall find some facts in your paper on intermediate varieties in intermediate regions, on which subject I have found remarkably little information. I cannot tell you how glad I am to hear that you have attended to the curious point of equatorial refrigeration. I quite agree that it must have been small; yet the more I go into that question the more convinced I feel that there was during the Glacial period some migration from north to south. The sketch in the "Origin" gives a very meagre account of my fuller MS. essay on this subject. I shall be particularly obliged for a copy of your paper when published (118/2. Probably a paper by Bates entitled "Contributions to an Insect Fauna of the Amazon Valley" ("Trans. Entomol. Soc." Volume V., page 335, 1858-61).); and if any suggestions occur to me (not that you require any) or questions, I will write and ask. I have at once to prepare a new edition of the "Origin," (118/3. Third Edition, March, 1861.), and I will do myself the pleasure of sending you a copy; but it will be only very slightly altered. Cases of neuter ants, divided into castes, with intermediate gradations (which I imagine are rare) interest me much. See "Origin" on the driver-ant, page 241 (please look at the passage.) LETTER 119. TO T.H. HUXLEY. (119/1. This refers to the first number of the new series of the "Natural History Review," 1861, a periodical which Huxley was largely instrumental in founding, and of which he was an editor (see Letter 107). The first series was published in Dublin, and ran to seven volumes between 1854 and 1860. The new series came to an end in 1865.) Down, January, 3rd [1861]. I have just finished No. 1 of the "Natural History Review," and must congratulate you, as chiefly concerned, on its excellence. The whole seems to me admirable,--so admirable that it is impossible that other numbers should be so good, but it would be foolish to expect it. I am rather a croaker, and I do rather fear that the merit of the articles will be above the run of common readers and subscribers. I have been much interested by your brain article. (119/2. The "Brain article" of Huxley bore the title "On the Zoological Relations of Man with the Lower Animals," and appeared in No. 1, January 1861, page 67. It was Mr. Huxley's vindication of the unqualified contradiction given by him at the Oxford meeting of the British Association to Professor Owen's assertions as to the difference between the brains of man and the higher apes. The sentence omitted by Owen in his lecture before the University of Cambridge was a footnote on the close structural resemblance between Homo and Pithecus, which occurs in his paper on the characters of the class Mammalia in the "Linn. Soc. Journal," Volume II., 1857, page 20. According to Huxley the lecture, or "Essay on the Classification of the Mammalia," was, with this omission, a reprint of the Linnean paper. In "Man's Place in Nature," page 110, note, Huxley remarks: "Surely it is a little singular that the 'anatomist,' who finds it 'difficult' to 'determine the difference' between Homo and Pithecus, should yet range them, on anatomical grounds, in distinct sub-classes.") What a complete and awful smasher (and done like a "buttered angel") it is for Owen! What a humbug he is to have left out the sentence in the lecture before the orthodox Cambridge dons! I like Lubbock's paper very much: how well he writes. (119/3. Sir John Lubbock's paper was a review of Leydig on the Daphniidae. M'Donnell's was "On the Homologies of the Electric Organ of the Torpedo," afterwards used in the "Origin" (see Edition VI., page 150).) M'Donnell, of course, pleases me greatly. But I am very curious to know who wrote the Protozoa article: I shall hear, if it be not a secret, from Lubbock. It strikes me as very good, and, by Jove, how Owen is shown up--"this great and sound reasoner"! By the way, this reminds me of a passage which I have just observed in Owen's address at Leeds, which a clever reviewer might turn into good fun. He defines (page xc) and further on amplifies his definition that creation means "a process he knows not what." And in a previous sentence he says facts shake his confidence that the Apteryx in New Zealand and Red Grouse in England are "distinct creations." So that he has no confidence that these birds were produced by "processes he knows not what!" To what miserable inconsistencies and rubbish this truckling to opposite opinions leads the great generaliser! (119/4. In the "Historical Sketch," which forms part of the later editions of the "Origin," Mr. Darwin made use of Owen's Leeds Address in the manner sketched above. See "Origin," Edition VI., page xvii.) Farewell: I heartily rejoice in the clear merit of this number. I hope Mrs. Huxley goes on well. Etty keeps much the same, but has not got up to the same pitch as when you were here. Farewell. LETTER 120. TO JAMES LAMONT. Down, February 25th [1861]. I am extremely much obliged for your very kind present of your beautiful work, "Seasons with the Sea-Horses;" and I have no doubt that I shall find much interesting from so careful and acute an observer as yourself. (120/1. "Seasons with the Sea-Horses; or, Sporting Adventures in the Northern Seas." London, 1861. Mr. Lamont (loc. cit., page 273) writes: "The polar bear seems to me to be nothing more than a variety of the bears inhabiting Northern Europe, Asia, and America; and it surely requires no very great stretch of the imagination to suppose that this variety was originally created, not as we see him now, but by individuals of Ursus arctos in Siberia, who, finding their means of subsistence running short, and pressed by hunger, ventured on the ice and caught some seals. These individuals would find that they could make a subsistence in this way, and would take up their residence on the shore and gradually take to a life on the ice...Then it stands to reason that those individuals who might happen to be palest in colour would have the best chance of succeeding in surprising seals...The process of Natural Selection would do the rest, and Ursus arctos would in the course of a few thousands, or a few millions of years, be transformed into the variety at present known as Ursus maritimus." The author adds the following footnote (op. cit., page 275): "It will be obvious to any one that I follow Mr. Darwin in these remarks; and, although the substance of this chapter was written in Spitzbergen, before "The Origin of Species" was published, I do not claim any originality for my views; and I also cheerfully acknowledge that, but for the publication of that work in connection with the name of so distinguished a naturalist, I never would have ventured to give to the world my own humble opinions on the subject.") P.S. I have just been cutting the leaves of your book, and have been very much pleased and surprised at your note about what you wrote in Spitzbergen. As you thought it out independently, it is no wonder that you so clearly understand Natural Selection, which so few of my reviewers do or pretend not to do. I never expected to see any one so heroically bold as to defend my bear illustration. (120/2. "In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching, almost like a whale, insects in the water."--"Origin," Edition VI., page 141. See Letter 110.) But a man who has done all that you have done must be bold! It is laughable how often I have been attacked and misrepresented about this bear. I am much pleased with your remarks, and thank you cordially for coming to the rescue. LETTER 121. TO W.B. TEGETMEIER. (121/1. Mr. Darwin's letters to Mr. Tegetmeier, taken as a whole, give a striking picture of the amount of assistance which Darwin received from him during many years. Some citations from these letters given in "Life and Letters," II., pages 52, 53, show how freely and generously Mr. Tegetmeier gave his help, and how much his co-operation was valued. The following letter is given as an example of the questions on which Darwin sought Mr. Tegetmeier's opinion and guidance.) Down, March 22 [1861]. I ought to have answered your last note sooner; but I have been very busy. How wonderfully successful you have been in breeding Pouters! You have a good right to be proud of your accuracy of eye and judgment. I am in the thick of poultry, having just commenced, and shall be truly grateful for the skulls, if you can send them by any conveyance to the Nag's Head next Thursday. You ask about vermilion wax: positively it was not in the state of comb, but in solid bits and cakes, which were thrown with other rubbish not far from my hives. You can make any use of the fact you like. Combs could be concentrically and variously coloured and dates recorded by giving for a few days wax darkly coloured with vermilion and indigo, and I daresay other substances. You ask about my crossed fowls, and this leads me to make a proposition to you, which I hope cannot be offensive to you. I trust you know me too well to think that I would propose anything objectionable to the best of my judgment. The case is this: for my object of treating poultry I must give a sketch of several breeds, with remarks on various points. I do not feel strong on the subject. Now, when my MS. is fairly copied in an excellent handwriting, would you read it over, which would take you at most an hour or two, and make comments in pencil on it; and accept, like a barrister, a fee, we will say, of a couple of guineas. This would be a great assistance to me, specially if you would allow me to put a note, stating that you, a distinguished judge and fancier, had read it over. I would state that you doubted or concurred, as each case might be, of course striking out what you were sure was incorrect. There would be little new in my MS. to you; but if by chance you used any of my facts or conclusions before I published, I should wish you to state that they were on my authority; otherwise I shall be accused of stealing from you. There will be little new, except that perhaps I have consulted some out-of-the-way books, and have corresponded with some good authorities. Tell me frankly what you think of this; but unless you will oblige me by accepting remuneration, I cannot and will not give you such trouble. I have little doubt that several points will arise which will require investigation, as I care for many points disregarded by fanciers; and according to any time thus spent, you will, I trust, allow me to make remuneration. I hope that you will grant me this favour. There is one assistance which I will now venture to beg of you--viz., to get me, if you can, another specimen of an old white Angora rabbit. I want it dead for the skeleton; and not knocked on the head. Secondly, I see in the "Cottage Gardener" (March 19th, page 375) there are impure half-lops with one ear quite upright and shorter than the other lopped ear. I much want a dead one. Baker cannot get one. Baily is looking out; but I want two specimens. Can you assist me, if you meet any rabbit-fancier? I have had rabbits with one ear more lopped than the other; but I want one with one ear quite upright and shorter, and the other quite long and lopped. LETTER 122. TO H.W. BATES. Down, March 26th [1861]. I have read your papers with extreme interest, and I have carefully read every word of them. (122/1. "Contributions to an Insect Fauna of the Amazon Valley." (Read March 5th and November 24th, 1860). "Entomological Soc. Trans." V., pages 223 and 335).) They seem to me to be far richer in facts of variation, and especially on the distribution of varieties and subspecies, than anything which I have read. Hereafter I shall re-read them, and hope in my future work to profit by them and make use of them. The amount of variation has much surprised me. The analogous variation of distinct species in the same regions strikes me as particularly curious. The greater variability of the female sex is new to me. Your Guiana case seems in some degree analogous, as far as plants are concerned, with the modern plains of La Plata, which seem to have been colonised from the north, but the species have been hardly modified. (122/2. Mr. Bates (page 349) gives reason to believe that the Guiana region should be considered "a perfectly independent province," and that it has formed a centre "whence radiated the species which now people the low lands on its borders.") Would you kindly answer me two or three questions if in your power? When species A becomes modified in another region into a well-marked form C, but is connected with it by one (or more) gradational forms B inhabiting an intermediate region; does this form B generally exist in equal numbers with A and C, OR INHABIT AN EQUALLY LARGE AREA? The probability is that you cannot answer this question, though one of your cases seems to bear on it... You will, I think, be glad to hear that I now often hear of naturalists accepting my views more or less fully; but some are curiously cautious in running the risk of any small odium in expressing their belief. LETTER 123. TO H.W. BATES. Down, April 4th [1861]. I have been unwell, so have delayed thanking you for your admirable letter. I hope you will not think me presumptuous in saying how much I have been struck with your varied knowledge, and with the decisive manner in which you bring it to bear on each point,--a rare and most high quality, as far as my experience goes. I earnestly hope you will find time to publish largely: before the Linnean Society you might bring boldly out your views on species. Have you ever thought of publishing your travels, and working in them the less abstruse parts of your Natural History? I believe it would sell, and be a very valuable contribution to Natural History. You must also have seen a good deal of the natives. I know well it would be quite unreasonable to ask for any further information from you; but I will just mention that I am now, and shall be for a long time, writing on domestic varieties of all animals. Any facts would be useful, especially any showing that savages take any care in breeding their animals, or in rejecting the bad and preserving the good; or any fancies which they may have that one coloured or marked dog, etc., is better than another. I have already collected much on this head, but am greedy for facts. You will at once see their bearing on variation under domestication. Hardly anything in your letter has pleased me more than about sexual selection. In my larger MS. (and indeed in the "Origin" with respect to the tuft of hairs on the breast of the cock-turkey) I have guarded myself against going too far; but I did not at all know that male and female butterflies haunted rather different sites. If I had to cut up myself in a review I would have [worried?] and quizzed sexual selection; therefore, though I am fully convinced that it is largely true, you may imagine how pleased I am at what you say on your belief. This part of your letter to me is a quintessence of richness. The fact about butterflies attracted by coloured sepals is another good fact, worth its weight in gold. It would have delighted the heart of old Christian C. Sprengel--now many years in his grave. I am glad to hear that you have specially attended to "mimetic" analogies--a most curious subject; I hope you publish on it. I have for a long time wished to know whether what Dr. Collingwood asserts is true--that the most striking cases generally occur between insects inhabiting the same country. LETTER 124. TO F.W. HUTTON. Down, April 20th [1861]. I hope that you will permit me to thank you for sending me a copy of your paper in "The Geologist" (124/1. In a letter to Hooker (April 23rd?, 1861) Darwin refers to Hutton's review as "very original," and adds that Hutton is "one of the very few who see that the change of species cannot be directly proved..." ("Life and Letters," II., page 362). The review appeared in "The Geologist" (afterwards known as "The Geological Magazine") for 1861, pages 132-6 and 183-8. A letter on "Difficulties of Darwinism" is published in the same volume of "The Geologist," page 286.), and at the same time to express my opinion that you have done the subject a real service by the highly original, striking, and condensed manner with which you have put the case. I am actually weary of telling people that I do not pretend to adduce direct evidence of one species changing into another, but that I believe that this view in the main is correct, because so many phenomena can be thus grouped together and explained. But it is generally of no use; I cannot make persons see this. I generally throw in their teeth the universally admitted theory of the undulation of light,--neither the undulation nor the very existence of ether being proved, yet admitted because the view explains so much. You are one of the very few who have seen this, and have now put it most forcibly and clearly. I am much pleased to see how carefully you have read my book, and, what is far more important, reflected on so many points with an independent spirit. As I am deeply interested in the subject (and I hope not exclusively under a personal point of view) I could not resist venturing to thank you for the right good service which you have done. I need hardly say that this note requires no answer. LETTER 125. TO J.D. HOOKER. (125/1. Parts of this letter are published in "Life and Letters," II., page 362.) Down, [April] 23rd, [1861]. I have been much interested by Bentham's paper in the "Natural History Review," but it would not, of course, from familiarity, strike you as it did me. (125/2. This refers to Bentham's paper "On the Species and Genera of Plants, etc." "Nat. Hist. Review," April, 1861, page 133, which is founded on, or extracted from, a paper read before the Linn. Soc., November 15th, 1858. It had been originally set down to be read on July 1st, 1858, but gave way to the papers of Darwin and Wallace. Mr. Bentham has described ("Life and Letters," II., page 294) how he reluctantly cancelled the parts urging "original fixity" of specific type, and the remainder seems not to have been published except in the above-quoted paper in the "Nat. Hist. Review.") I liked the whole--all the facts on the nature of close and varying species. Good Heavens! to think of the British botanists turning up their noses and saying that he knows nothing of British plants! I was also pleased at his remarks on classification, because it showed me that I wrote truly on this subject in the "Origin." I saw Bentham at the Linnean Society, and had some talk with him and Lubbock and Edgeworth, Wallich, and several others. I asked Bentham to give us his ideas of species; whether partially with us or dead against us, he would write excellent matter. He made no answer, but his manner made me think he might do so if urged--so do you attack him. Every one was speaking with affection and anxiety of Henslow. I dined with Bell at the Linnean Club, and liked my dinner...dining-out is such a novelty to me that I enjoyed it. Bell has a real good heart. I liked Rolleston's paper, but I never read anything so obscure and not self-evident as his "canons." (125/3. See "Nat. Hist. Review," 1861, page 206. The paper is "On the Brain of the Orang Utang," and forms part of the bitter controversy of this period to which reference occurs in letters to Huxley and elsewhere in these volumes. Rolleston's work is quoted by Huxley ("Man's Place in Nature," page 117) as part of the crushing refutation of Owen's position. Mr. Huxley's letter referred to above is no doubt that in the "Athenaeum," April 13th, 1861, page 498; it is certainly severe, but to those who know Mr. Huxley's "Succinct History of the Controversy," etc. ("Man's Place in Nature," page 113), it will not seem too severe.) I had a dim perception of the truth of your profound remark--that he wrote in fear and trembling "of God, man, and monkeys," but I would alter it into "God, man, Owen, and monkeys." Huxley's letter was truculent, and I see that every one thinks it too truculent; but in simple truth I am become quite demoniacal about Owen--worse than Huxley; and I told Huxley that I should put myself under his care to be rendered milder. But I mean to try and get more angelic in my feelings; yet I never shall forget his cordial shake of the hand, when he was writing as spitefully as he possibly could against me. But I have always thought that you have more cause than I to be demoniacally inclined towards him. Bell told me that Owen says that the editor mutilated his article in the "Edinburgh Review" (125/4. This is the only instance, with which we are acquainted, of Owen's acknowledging the authorship of the "Edinburgh Review" article.), and Bell seemed to think it was rendered more spiteful by the Editor; perhaps the opposite view is as probable. Oh, dear! this does not look like becoming more angelic in my temper! I had a splendid long talk with Lyell (you may guess how splendid, for he was many times on his knees, with elbows on the sofa) (125/5. Mr. Darwin often spoke of Sir Charles Lyell's tendency to take curious attitudes when excited.) on his work in France: he seems to have done capital work in making out the age of the celt-bearing beds, but the case gets more and more complicated. All, however, tends to greater and greater antiquity of man. The shingle beds seem to be estuary deposits. I called on R. Chambers at his very nice house in St. John's Wood, and had a very pleasant half-hour's talk--he is really a capital fellow. He made one good remark and chuckled over it: that the laymen universally had treated the controversy on the "Essays and Reviews" as a merely professional subject, and had not joined in it but had left it to the clergy. I shall be anxious for your next letter about Henslow. Farewell, with sincere sympathy, my old friend. P.S.--We are very much obliged for "London Review." We like reading much of it, and the science is incomparably better than in the "Athenaeum." You shall not go on very long sending it, as you will be ruined by pennies and trouble; but I am under a horrid spell to the "Athenaeum" and "Gardeners' Chronicle," both of which are intolerably dull, but I have taken them in for so many years that I cannot give them up. The "Cottage Gardener," for my purpose, is now far better than the "Gardeners' Chronicle." LETTER 126. TO J.L.A. DE QUATREFAGES. Down, April 25 [1861]. I received this morning your "Unite de l'Espece Humaine" [published in 1861], and most sincerely do I thank you for this your very kind present. I had heard of and been recommended to read your articles, but, not knowing that they were separately published, did not know how to get them. So your present is most acceptable, and I am very anxious to see your views on the whole subject of species and variation; and I am certain to derive much benefit from your work. In cutting the pages I observe that you have most kindly mentioned my work several times. My views spread slowly in England and America; and I am much surprised to find them most commonly accepted by geologists, next by botanists, and least by zoologists. I am much pleased that the younger and middle-aged geologists are coming round, for the arguments from Geology have always seemed strongest against me. Not one of the older geologists (except Lyell) has been even shaken in his views of the eternal immutability of species. But so many of the younger men are turning round with zeal that I look to the future with some confidence. I am now at work on "Variation under Domestication," but make slow progress--it is such tedious work comparing skeletons. With very sincere thanks for the kind sympathy which you have always shown me, and with much respect,... P.S.--I have lately read M. Naudin's paper (126/1. Naudin's paper ("Revue Horticole," 1852) is mentioned in the "Historical Sketch" prefixed to the later editions of the "Origin" (Edition VI., page xix). Naudin insisted that species are formed in a manner analogous to the production of varieties by cultivators, i.e., by selection, "but he does not show how selection acts under nature." In the "Life and Letters," II., page 246, Darwin, speaking of Naudin's work, says: "Decaisne seems to think he gives my whole theory."), but it does not seem to me to anticipate me, as he does not show how selection could be applied under nature; but an obscure writer (126/2. The obscure writer is Patrick Matthew (see the "Historical Sketch" in the "Origin.") on forest trees, in 1830, in Scotland, most expressly and clearly anticipated my views--though he put the case so briefly that no single person ever noticed the scattered passages in his book. LETTER 127. TO L. HINDMARSH. (127/1. The following letter was in reply to one from Mr. Hindmarsh, to whom Mr. Darwin had written asking for information on the average number of animals killed each year in the Chillingham herd. The object of the request was to obtain information which might throw light on the rate of increase of the cattle relatively to those on the pampas of South America. Mr. Hindmarsh had contributed a paper "On the Wild Cattle of Chillingham Park" to the "Annals and Mag. Nat. Hist." Volume II., page 274, 1839.) Down, May 12th [1861]. I thank you sincerely for your prompt and great kindness, and return the letter, which I have been very glad to see and have had copied. The increase is more rapid than I anticipated, but it seems rather conjectural; I had hoped that in so interesting a case some exact record had been kept. The number of births, or of calves reared till they followed their mothers, would perhaps have been the best datum. From Mr. Hardy's letter I infer that ten must be annually born to make up the deaths from various causes. In Paraguay, Azara states that in a herd of 4,000, from 1,000 to 1,300 are reared; but then, though they do not kill calves, but castrate the young bulls, no doubt the oxen would be killed earlier than the cows, so that the herd would contain probably more of the female sex than the herd at Chillingham. There is not apparently any record whether more young bulls are killed than cows. I am surprised that Lord Tankerville does not have an exact record kept of deaths and sexes and births: after a dozen years it would be an interesting statistical record to the naturalist and agriculturist. (PLATE: PROFESSOR HENSLOW.) LETTER 128. TO J.D. HOOKER. (128/1. The death of Professor Henslow (who was Sir J.D. Hooker's father-in-law) occurred on May 16th, 1861.) Down, May 24th [1861]. Thanks for your two notes. I am glad that the burial is over, and sincerely sympathise and can most fully understand your feelings at your loss. I grieve to think how little I saw of Henslow for many years. With respect to a biography of Henslow, I cannot help feeling rather doubtful, on the principle that a biography could not do him justice. His letters were generally written in a hurry, and I fear he did not keep any journal or diary. If there were any vivid materials to describe his life as parish priest, and manner of managing the poor, it would be very good. I am never very sanguine on literary projects. I cannot help fearing his Life might turn out flat. There can hardly be marked incidents to describe. I sincerely hope that I take a wrong and gloomy view, but I cannot help fearing--I would rather see no Life than one that would interest very few. It will be a pleasure and duty in me to consider what I can recollect; but at present I can think of scarcely anything. The equability and perfection of Henslow's whole character, I should think, would make it very difficult for any one to pourtray him. I have been thinking about Henslow all day a good deal, but the more I think the less I can think of to write down. It is quite a new style for me to set about, but I will continue to think what I could say to give any, however imperfect, notion of him in the old Cambridge days. Pray give my kindest remembrances to L. Jenyns (128/2. The Rev. Leonard Jenyns (afterwards Blomefield) undertook the "Life" of Henslow, to which Darwin contributed a characteristic and delightful sketch. See Letter 17.), who is often associated with my recollection of those old happy days. LETTER 129. HENRY FAWCETT TO CHARLES DARWIN. (129/1. It was in reply to the following letter that Darwin wrote to Fawcett: "You could not possibly have told me anything which would have given me more satisfaction than what you say about Mr. Mill's opinion. Until your review appeared I began to think that perhaps I did not understand at all how to reason scientifically." ("Life of Henry Fawcett," by Leslie Stephen, 1885, page 100.) Bodenham, Salisbury, July 16th [1861]. I feel that I ought not to have so long delayed writing to thank you for your very kind letter to me about my article on your book in "Macmillan's Magazine." I was particularly anxious to point out that the method of investigation pursued was in every respect philosophically correct. I was spending an evening last week with my friend Mr. John Stuart Mill, and I am sure you will be pleased to hear from such an authority that he considers that your reasoning throughout is in the most exact accordance with the strict principles of logic. He also says the method of investigation you have followed is the only one proper to such a subject. It is easy for an antagonistic reviewer, when he finds it difficult to answer your arguments, to attempt to dispose of the whole matter by uttering some such commonplace as "This is not a Baconian induction." I expect shortly to be spending a few days in your neighbourhood, and if I should not be intruding upon you, I should esteem it a great favour if you will allow me to call on you, and have half an hour's conversation with you. As far as I am personally concerned, I am sure I ought to be grateful to you, for since my accident nothing has given me so much pleasure as the perusal of your book. Such studies are now a great resource to me. LETTER 130. TO C. LYELL. 2, Hesketh Terrace, Torquay [August 2nd, 1861]. I declare that you read the reviews on the "Origin" more carefully than I do. I agree with all your remarks. The point of correlation struck me as well put, and on varieties growing together; but I have already begun to put things in train for information on this latter head, on which Bronn also enlarges. With respect to sexuality, I have often speculated on it, and have always concluded that we are too ignorant to speculate: no physiologist can conjecture why the two elements go to form a new being, and, more than that, why nature strives at uniting the two elements from two individuals. What I am now working at in my orchids is an admirable illustration of the law. I should certainly conclude that all sexuality had descended from one prototype. Do you not underrate the degree of lowness of organisation in which sexuality occurs--viz., in Hydra, and still lower in some of the one-celled free confervae which "conjugate," which good judges (Thwaites) believe is the simplest form of true sexual generation? (130/1. See Letter 97.) But the whole case is a mystery. There is another point on which I have occasionally wished to say a few words. I believe you think with Asa Gray that I have not allowed enough for the stream of variation having been guided by a higher power. I have had lately a good deal of correspondence on this head. Herschel, in his "Physical Geography" (130/2. "Physical Geography of the Globe," by Sir John F.W. Herschel, Edinburgh, 1861. On page 12 Herschel writes of the revelations of Geology pointing to successive submersions and reconstructions of the continents and fresh races of animals and plants. He refers to a "great law of change" which has not operated either by a gradually progressing variation of species, nor by a sudden and total abolition of one race...The following footnote on page 12 of the "Physical Geography" was added in January, 1861: "This was written previous to the publication of Mr. Darwin's work on the "Origin of Species," a work which, whatever its merit or ingenuity, we cannot, however, consider as having disproved the view taken in the text. We can no more accept the principle of arbitrary and casual variation and natural selection as a sufficient account, per se, of the past and present organic world, than we can receive the Laputan method of composing books (pushed a outrance) as a sufficient one of Shakespeare and the "Principia." Equally in either case an intelligence, guided by a purpose, must be continually in action to bias the directions of the steps of change--to regulate their amount, to limit their divergence, and to continue them in a definite course. We do not believe that Mr. Darwin means to deny the necessity of such intelligent direction. But it does not, so far as we can see, enter into the formula of this law, and without it we are unable to conceive how far the law can have led to the results. On the other hand, we do not mean to deny that such intelligence may act according to a law (that is to say, on a preconceived and definite plan). Such law, stated in words, would be no other than the actual observed law of organic succession; a one more general, taking that form when applied to our own planet, and including all the links of the chain which have disappeared. BUT THE ONE LAW IS A NECESSARY SUPPLEMENT TO THE OTHER, AND OUGHT, IN ALL LOGICAL PROPRIETY, TO FORM A PART OF ITS ENUNCIATION. Granting this, and with some demur as to the genesis of man, we are far from disposed to repudiate the view taken of this mysterious subject in Mr. Darwin's book." The sentence in italics is no doubt the one referred to in the letter to Lyell. See Letter 243.), has a sentence with respect to the "Origin," something to the effect that the higher law of Providential Arrangement should always be stated. But astronomers do not state that God directs the course of each comet and planet. The view that each variation has been providentially arranged seems to me to make Natural Selection entirely superfluous, and indeed takes the whole case of the appearance of new species out of the range of science. But what makes me most object to Asa Gray's view is the study of the extreme variability of domestic animals. He who does not suppose that each variation in the pigeon was providentially caused, by accumulating which variations, man made a Fantail, cannot, I think, logically argue that the tail of the woodpecker was formed by variations providentially ordained. It seems to me that variations in the domestic and wild conditions are due to unknown causes, and are without purpose, and in so far accidental; and that they become purposeful only when they are selected by man for his pleasure, or by what we call Natural Selection in the struggle for life, and under changing conditions. I do not wish to say that God did not foresee everything which would ensue; but here comes very nearly the same sort of wretched imbroglio as between freewill and preordained necessity. I doubt whether I have made what I think clear; but certainly A. Gray's notion of the courses of variation having been led like a stream of water by gravity, seems to me to smash the whole affair. It reminds me of a Spaniard whom I told I was trying to make out how the Cordillera was formed; and he answered me that it was useless, for "God made them." It may be said that God foresaw how they would be made. I wonder whether Herschel would say that you ought always to give the higher providential law, and declare that God had ordered all certain changes of level, that certain mountains should arise. I must think that such views of Asa Gray and Herschel merely show that the subject in their minds is in Comte's theological stage of science... Of course I do not want any answer to my quasi-theological discussion, but only for you to think of my notions, if you understand them. I hope to Heaven your long and great labours on your new edition are drawing to a close. LETTER 131. TO C. LYELL. Torquay, [August 13th, 1861]. Very many thanks for the orchids, which have proved extremely useful to me in two ways I did not anticipate, but were too monstrous (yet of some use) for my special purpose. When you come to "Deification" (131/1. See Letter 105, note.), ask yourself honestly whether what you are thinking applies to the endless variations of domestic productions, which man accumulates for his mere fancy or use. No doubt these are all caused by some unknown law, but I cannot believe they were ordained for any purpose, and if not so ordained under domesticity, I can see no reason to believe that they were ordained in a state of nature. Of course it may be said, when you kick a stone, or a leaf falls from a tree, that it was ordained, before the foundations of the world were laid, exactly where that stone or leaf should lie. In this sense the subject has no interest for me. Once again, many thanks for the orchids; you must let me repay you what you paid the collector. LETTER 132. TO C. LYELL. (132/1. The first paragraph probably refers to the proof-sheets of Lyell's "Antiquity of Man," but the passage referred to seems not to occur in the book.) Torquay, August 21st [1861]. ...I have really no criticism, except a trifling one in pencil near the end, which I have inserted on account of dominant and important species generally varying most. You speak of "their views" rather as if you were a thousand miles away from such wretches, but your concluding paragraph shows that you are one of the wretches. I am pleased that you approve of Hutton's review. (132/2. "Some Remarks on Mr. Darwin's Theory," by F.W. Hutton. "Geologist," Volume IV., page 132 (1861). See Letter 124.) It seemed to me to take a more philosophical view of the manner of judging the question than any other review. The sentence you quote from it seems very true, but I do not agree with the theological conclusion. I think he quotes from Asa Gray, certainly not from me; but I have neither A. Gray nor "Origin" with me. Indeed, I have over and over again said in the "Origin" that Natural Selection does nothing without variability; I have given a whole chapter on laws, and used the strongest language how ignorant we are on these laws. But I agree that I have somehow (Hooker says it is owing to my title) not made the great and manifest importance of previous variability plain enough. Breeders constantly speak of Selection as the one great means of improvement; but of course they imply individual differences, and this I should have thought would have been obvious to all in Natural Selection; but it has not been so. I have just said that I cannot agree with "which variations are the effects of an unknown law, ordained and guided without doubt by an intelligent cause on a preconceived and definite plan." Will you honestly tell me (and I should be really much obliged) whether you believe that the shape of my nose (eheu!) was ordained and "guided by an intelligent cause?" (132/3. It should be remembered that the shape of his nose nearly determined Fitz-Roy to reject Darwin as naturalist to H.M.S. "Beagle" ("Life and Letters," I., page 60).) By the selection of analogous and less differences fanciers make almost generic differences in their pigeons; and can you see any good reason why the Natural Selection of analogous individual differences should not make new species? If you say that God ordained that at some time and place a dozen slight variations should arise, and that one of them alone should be preserved in the struggle for life and the other eleven should perish in the first or few first generations, then the saying seems to me mere verbiage. It comes to merely saying that everything that is, is ordained. Let me add another sentence. Why should you or I speak of variation as having been ordained and guided, more than does an astronomer, in discussing the fall of a meteoric stone? He would simply say that it was drawn to our earth by the attraction of gravity, having been displaced in its course by the action of some quite unknown laws. Would you have him say that its fall at some particular place and time was "ordained and guided without doubt by an intelligent cause on a preconceived and definite plan"? Would you not call this theological pedantry or display? I believe it is not pedantry in the case of species, simply because their formation has hitherto been viewed as beyond law; in fact, this branch of science is still with most people under its theological phase of development. The conclusion which I always come to after thinking of such questions is that they are beyond the human intellect; and the less one thinks on them the better. You may say, Then why trouble me? But I should very much like to know clearly what you think. LETTER 133. TO HENRY FAWCETT. (133/1. The following letter was published in the "Life" of Mr. Fawcett (1885); we are indebted to Mrs. Fawcett and Messrs. Smith & Elder for permission to reprint it. See Letter 129.) September 18th [1861]. I wondered who had so kindly sent me the newspaper (133/2. The newspaper sent was the "Manchester Examiner" for September 9th, 1861, containing a report of Mr. Fawcett's address given before Section D of the British Association, "On the method of Mr. Darwin in his treatise on the origin of species," in which the speaker showed that the "method of investigation pursued by Mr. Darwin in his treatise on the origin of species is in strict accordance with the principles of logic." The "A" of the letter (as published in Fawcett's Life) is the late Professor Williamson, who is reported to have said that "while he would not say that Mr. Darwin's book had caused him a loss of reputation, he was sure that it had not caused a gain." The reference to "B" is explained by the report of the late Dr. Lankester's speech in which he said, "The facts brought forward in support of the hypothesis had a very different value indeed from that of the hypothesis...A great naturalist, who was still a friend of Mr. Darwin, once said to him (Dr. Lankester), 'The mistake is, that Darwin has dealt with origin. Why did he not put his facts before us, and let them rest?'" Another speaker, the Rt. Hon. J.R. Napier, remarked: "I am going to speak closely to the question. If the hypothesis is put forward to contradict facts, and the averments are contrary to the Word of God, I say that it is not a logical argument." At this point the chairman, Professor Babington, wisely interfered, on the ground that the meeting was a scientific one.), which I was very glad to see; and now I have to thank you sincerely for allowing me to see your MS. It seems to me very good and sound; though I am certainly not an impartial judge. You will have done good service in calling the attention of scientific men to means and laws of philosophising. As far as I could judge by the papers, your opponents were unworthy of you. How miserably A. talked of my reputation, as if that had anything to do with it!...How profoundly ignorant B must be of the very soul of observation! About thirty years ago there was much talk that geologists ought only to observe and not theorise; and I well remember some one saying that at this rate a man might as well go into a gravel-pit and count the pebbles and describe the colours. How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service! I have returned only lately from a two months' visit to Torquay, which did my health at the time good; but I am one of those miserable creatures who are never comfortable for twenty-four hours; and it is clear to me that I ought to be exterminated. I have been rather idle of late, or, speaking more strictly, working at some miscellaneous papers, which, however, have some direct bearing on the subject of species; yet I feel guilty at having neglected my larger book. But, to me, observing is much better sport than writing. I fear that I shall have wearied you with this long note. Pray believe that I feel sincerely grateful that you have taken up the cudgels in defence of the line of argument in the "Origin;" you will have benefited the subject. Many are so fearful of speaking out. A German naturalist came here the other day; and he tells me that there are many in Germany on our side, but that all seem fearful of speaking out, and waiting for some one to speak, and then many will follow. The naturalists seem as timid as young ladies should be, about their scientific reputation. There is much discussion on the subject on the Continent, even in quiet Holland; and I had a pamphlet from Moscow the other day by a man who sticks up famously for the imperfection of the "Geological Record," but complains that I have sadly understated the variability of the old fossilised animals! But I must not run on. LETTER 134. TO H.W. BATES. Down, September 25th [1861]. Now for a few words on science. Many thanks for facts on neuters. You cannot tell how I rejoice that you do not think what I have said on the subject absurd. Only two persons have even noticed it to me--viz., the bitter sneer of Owen in the "Edinburgh Review" (134/1. "Edinburgh Review," April, 1860, page 525.), and my good friend and supporter, Sir C. Lyell, who could only screw up courage to say, "Well, you have manfully faced the difficulty." What a wonderful case of Volucella of which I had never heard. (134/2. Volucella is a fly--one of the Syrphidae--supposed to supply a case of mimicry; this was doubtless the point of interest with Bates. Dr. Sharp says ["Insects," Part II. (in the Camb. Nat. Hist. series), 1899, page 500]: "It was formerly assumed that the Volucella larvae lived on the larvae of the bees, and that the parent flies were providentially endowed with a bee-like appearance that they might obtain entrance into the bees' nests without being detected." Dr. Sharp goes on to say that what little is known on the subject supports the belief that the "presence of the Volucella in the nests is advantageous to both fly and bee.") I had no idea such a case occurred in nature; I must get and see specimens in British Museum. I hope and suppose you will give a good deal of Natural History in your Travels; every one cares about ants--more notice has been taken about slave-ants in the "Origin" than of any other passage. I fully expect to delight in your Travels. Keep to simple style, as in your excellent letters,--but I beg pardon, I am again advising. What a capital paper yours will be on mimetic resemblances! You will make quite a new subject of it. I had thought of such cases as a difficulty; and once, when corresponding with Dr. Collingwood, I thought of your explanation; but I drove it from my mind, for I felt that I had not knowledge to judge one way or the other. Dr C., I think, states that the mimetic forms inhabit the same country, but I did not know whether to believe him. What wonderful cases yours seem to be! Could you not give a few woodcuts in your Travels to illustrate this? I am tired with a hard day's work, so no more, except to give my sincere thanks and hearty wishes for the success of your Travels. LETTER 135. TO J.D. HOOKER. Down, March 18th [1862]. Your letter discusses lots of interesting subjects, and I am very glad you have sent for your letter to Bates. (135/1. Published in Mr. Clodd's memoir of Bates in the "Naturalist on the Amazons," 1892, page l.) What do you mean by "individual plants"? (135/2. In a letter to Mr. Darwin dated March 17th, 1862, Sir J.D. Hooker had discussed a supposed difference between animals and plants, "inasmuch as the individual animal is certainly changed materially by external conditions, the latter (I think) never, except in such a coarse way as stunting or enlarging--e.g. no increase of cold on the spot, or change of individual plant from hot to cold, will induce said individual plant to get more woolly covering; but I suppose a series of cold seasons would bring about such a change in an individual quadruped, just as rowing will harden hands, etc.") I fancied a bud lived only a year, and you could hardly expect any change in that time; but if you call a tree or plant an individual, you have sporting buds. Perhaps you mean that the whole tree does not change. Tulips, in "breaking," change. Fruit seems certainly affected by the stock. I think I have (135/3. See note, Letter 16.) got cases of slight change in alpine plants transplanted. All these subjects have rather gone out of my head owing to orchids, but I shall soon have to enter on them in earnest when I come again to my volume on variation under domestication. ...In the lifetime of an animal you would, I think, find it very difficult to show effects of external condition on animals more than shade and light, good and bad soil, produce on a plant. You speak of "an inherent tendency to vary wholly independent of physical conditions"! This is a very simple way of putting the case (as Dr. Prosper Lucas also puts it) (135/4. Prosper Lucas, the author of "Traite philosophique et physiologique de l'heredite naturelle dans les etats de sante et de maladie du systeme nerveux": 2 volumes, Paris, 1847-50.): but two great classes of facts make me think that all variability is due to change in the conditions of life: firstly, that there is more variability and more monstrosities (and these graduate into each other) under unnatural domestic conditions than under nature; and, secondly, that changed conditions affect in an especial manner the reproductive organs--those organs which are to produce a new being. But why one seedling out of thousands presents some new character transcends the wildest powers of conjecture. It was in this sense that I spoke of "climate," etc., possibly producing without selection a hooked seed, or any not great variation. (135/5. This statement probably occurs in a letter, and not in Darwin's published works.) I have for years and years been fighting with myself not to attribute too much to Natural Selection--to attribute something to direct action of conditions; and perhaps I have too much conquered my tendency to lay hardly any stress on conditions of life. I am not shaken about "saltus" (135/6. Sir Joseph had written, March 17th, 1862: "Huxley is rather disposed to think you have overlooked saltus, but I am not sure that he is right--saltus quoad individuals is not saltus quoad species--as I pointed out in the Begonia case, though perhaps that was rather special pleading in the present state of science." For the Begonia case, see "Life and Letters," II., page 275, also letter 110, page 166.), I did not write without going pretty carefully into all the cases of normal structure in animals resembling monstrosities which appear per saltus. LETTER 136. TO J.D. HOOKER. 26th [March, 1862]. Thanks also for your own (136/1. See note in Letter 135.) and Bates' letter now returned. They are both excellent; you have, I think, said all that can be said against direct effects of conditions, and capitally put. But I still stick to my own and Bates' side. Nevertheless I am pleased to attribute little to conditions, and I wish I had done what you suggest--started on the fundamental principle of variation being an innate principle, and afterwards made a few remarks showing that hereafter, perhaps, this principle would be explicable. Whenever my book on poultry, pigeons, ducks, and rabbits is published, with all the measurements and weighings of bones, I think you will see that "use and disuse" at least have some effect. I do not believe in perfect reversion. I rather demur to your doctrine of "centrifugal variation." (136/2. The "doctrine of centrifugal variation" is given in Sir J.D. Hooker's "Introductory Essay to the Flora of Tasmania" (Part III. of the Botany of the Antarctic Expedition), 1859, page viii. In paragraph 10 the author writes: "The tendency of varieties, both in nature and under cultivation...is rather to depart more and more widely from the original type than to revert to it." In Sir Joseph's letter to Bates (loc. cit., page lii) he wrote: "Darwin also believes in some reversion to type which is opposed to my view of variation." It may be noted in this connection that Mr. Galton has shown reason to believe in a centripetal tendency in variation (to use Hooker's phraseology) which is not identical with the reversion of cultivated plants to their ancestors, the case to which Hooker apparently refers. See "Natural Inheritance," by F. Galton, 1889.) I suppose you do not agree with or do not remember my doctrine of the good of diversification (136/3. Darwin usually used the word "divergence" in this connection.); this seems to me amply to account for variation being centrifugal--if you forget it, look at this discussion (page 117 of 3rd edition), it was the best point which, according to my notions, I made out, and it has always pleased me. It is really curiously satisfactory to me to see so able a man as Bates (and yourself) believing more fully in Natural Selection than I think I even do myself. (136/4. This refers to a very interesting passage in Hooker's letter to Bates (loc. cit., page liii): "I am sure that with you, as with me, the more you think the less occasion you will see for anything but time and natural selection to effect change; and that this view is the simplest and clearest in the present state of science is one advantage, at any rate. Indeed, I think that it is, in the present state of the inquiry, the legitimate position to take up; it is time enough to bother our heads with the secondary cause when there is some evidence of it or some demand for it--at present I do not see one or the other, and so feel inclined to renounce any other for the present.") By the way, I always boast to you, and so I think Owen will be wrong that my book will be forgotten in ten years, for a French edition is now going through the press and a second German edition wanted. Your long letter to Bates has set my head working, and makes me repent of the nine months spent on orchids; though I know not why I should not have amused myself on them as well as slaving on bones of ducks and pigeons, etc. The orchids have been splendid sport, though at present I am fearfully sick of them. I enclose a waste copy of woodcut of Mormodes ignea; I wish you had a plant at Kew, for I am sure its wonderful mechanism and structure would amuse you. Is it not curious the way the labellum sits on the top of the column?--here insects alight and are beautifully shot, when they touch a certain sensitive point, by the pollinia. How kindly you have helped me in my work! Farewell, my dear old fellow. LETTER 137. TO H.W. BATES. Down, May 4th [1862]. Hearty thanks for your most interesting letter and three very valuable extracts. I am very glad that you have been looking at the South Temperate insects. I wish that the materials in the British Museum had been richer; but I should think the case of the South American Carabi, supported by some other case, would be worth a paper. To us who theorise I am sure the case is very important. Do the South American Carabi differ more from the other species than do, for instance, the Siberian and European and North American and Himalayan (if the genus exists there)? If they do, I entirely agree with you that the difference would be too great to account for by the recent Glacial period. I agree, also, with you in utterly rejecting an independent origin for these Carabi. There is a difficulty, as far as I know, in our ignorance whether insects change quickly in time; you could judge of this by knowing how far closely allied coleoptera generally have much restricted ranges, for this almost implies rapid change. What a curious case is offered by land-shells, which become modified in every sub-district, and have yet retained the same general structure from very remote geological periods! When working at the Glacial period, I remember feeling much surprised how few birds, no mammals, and very few sea-mollusca seemed to have crossed, or deeply entered, the inter-tropical regions during the cold period. Insects, from all you say, seem to come under the same category. Plants seem to migrate more readily than animals. Do not underrate the length of Glacial period: Forbes used to argue that it was equivalent to the whole of the Pleistocene period in the warmer latitudes. I believe, with you, that we shall be driven to an older Glacial period. I am very sorry to hear about the British Museum; it would be hopeless to contend against any one supported by Owen. Perhaps another chance might occur before very long. How would it be to speak to Owen as soon as your own mind is made up? From what I have heard, since talking to you, I fear the strongest personal interest with a Minister is requisite for a pension. Farewell, and may success attend the acerrimo pro-pugnatori. P.S. I deeply wish you could find some situation in which you could give your time to science; it would be a great thing for science and for yourself. LETTER 138. TO J.L.A. DE QUATREFAGES. Down, July 11th [1862]. I thank you cordially for so kindly and promptly answering my questions. I will quote some of your remarks. The case seems to me of some importance with reference to my heretical notions, for it shows how larvae might be modified. I shall not publish, I daresay, for a year, for much time is expended in experiments. If within this time you should acquire any fresh information on the similarity of the moths of distinct races, and would allow me to quote any facts on your authority, I should feel very grateful. I thank you for your great kindness with respect to the translation of the "Origin;" it is very liberal in you, as we differ to a considerable degree. I have been atrociously abused by my religious countrymen; but as I live an independent life in the country, it does not in the least hurt me in any way, except indeed when the abuse comes from an old friend like Professor Owen, who abuses me and then advances the doctrine that all birds are probably descended from one parent. I wish the translator (138/1. Mdlle. Royer, who translated the first French edition of the "Origin.') had known more of Natural History; she must be a clever but singular lady, but I never heard of her till she proposed to translate my book. LETTER 139. TO ASA GRAY. Down, July 23rd [1862]. I received several days ago two large packets, but have as yet read only your letter; for we have been in fearful distress, and I could attend to nothing. Our poor boy had the rare case of second rash and sore throat...; and, as if this was not enough, a most serious attack of erysipelas, with typhoid symptoms. I despaired of his life; but this evening he has eaten one mouthful, and I think has passed the crisis. He has lived on port wine every three-quarters of an hour, day and night. This evening, to our astonishment, he asked whether his stamps were safe, and I told him of one sent by you, and that he should see it to-morrow. He answered, "I should awfully like to see it now"; so with difficulty he opened his eyelids and glanced at it, and, with a sigh of satisfaction, said, "All right." Children are one's greatest happiness, but often and often a still greater misery. A man of science ought to have none--perhaps not a wife; for then there would be nothing in this wide world worth caring for, and a man might (whether he could is another question) work away like a Trojan. I hope in a few days to get my brains in order, and then I will pick out all your orchid letters, and return them in hopes of your making use of them... Of all the carpenters for knocking the right nail on the head, you are the very best; no one else has perceived that my chief interest in my orchid book has been that it was a "flank movement" on the enemy. I live in such solitude that I hear nothing, and have no idea to what you allude about Bentham and the orchids and species. But I must enquire. By the way, one of my chief enemies (the sole one who has annoyed me), namely Owen, I hear has been lecturing on birds; and admits that all have descended from one, and advances as his own idea that the oceanic wingless birds have lost their wings by gradual disuse. He never alludes to me, or only with bitter sneers, and coupled with Buffon and the "Vestiges." Well, it has been an amusement to me this first evening, scribbling as egotistically as usual about myself and my doings; so you must forgive me, as I know well your kind heart will do. I have managed to skim the newspaper, but had not heart to read all the bloody details. Good God! What will the end be? Perhaps we are too despondent here; but I must think you are too hopeful on your side of the water. I never believed the "canards" of the army of the Potomac having capitulated. My good dear wife and self are come to wish for peace at any price. Good night, my good friend. I will scribble on no more. One more word. I should like to hear what you think about what I say in the last chapter of the orchid book on the meaning and cause of the endless diversity of means for the same general purpose. It bears on design, that endless question. Good night, good night! LETTER 140. TO C. LYELL. 1, Carlton Terrace, Southampton, August 22nd [1862]. You say that the Bishop and Owen will be down on you (140/1. This refers to the "Antiquity of Man," which was published in 1863.): the latter hardly can, for I was assured that Owen, in his lectures this spring, advanced as a new idea that wingless birds had lost their wings by disuse. (140/2. The first paragraph of this letter was published in "Life and Letters," II., pages 387, 388.) Also that magpies stole spoons, etc., from a remnant of some instinct like that of the bower-bird, which ornaments its playing passage with pretty feathers. Indeed, I am told that he hinted plainly that all birds are descended from one. What an unblushing man he must be to lecture thus after abusing me so, and never to have openly retracted, or alluded to my book! LETTER 141. TO JOHN LUBBOCK (LORD AVEBURY). Cliff Cottage, Bournemouth, September 5th [1862]. Many thanks for your pleasant note in return for all my stupid trouble. I did not fully appreciate your insect-diving case (141/1. "On two Aquatic Hymenoptera, one of which uses its Wings in Swimming." By John Lubbock. "Trans. Linn. Soc." Volume XXIV., 1864, pages 135-42.) [Read May 7th, 1863.] In this paper Lubbock describes a new species of Polynema--P. natans--which swims by means of its wings, and is capable of living under water for several hours; the other species, referred to a new genus Prestwichia, lives under water, holds its wings motionless and uses its legs as oars.) before your last note, nor had I any idea that the fact was new, though new to me. It is really very interesting. Of course you will publish an account of it. You will then say whether the insect can fly well through the air. (141/2. In describing the habits of Polynema, Lubbock writes, "I was unfortunately unable to ascertain whether they could fly" (loc. cit., page 137).) My wife asked, "How did he find that it stayed four hours under water without breathing?" I answered at once: "Mrs. Lubbock sat four hours watching." I wonder whether I am right. I long to be at home and at steady work, and I hope we may be in another month. I fear it is hopeless my coming to you, for I am squashier than ever, but hope two shower-baths a day will give me a little strength, so that you will, I hope, come to us. It is an age since I have seen you or any scientific friend. I heard from Lyell the other day in the Isle of Wight, and from Hooker in Scotland. About Huxley I know nothing, but I hope his book progresses, for I shall be very curious to see it. (141/3. "Man's Place in Nature." London, 1863.) I do nothing here except occasionally look at a few flowers, and there are very few here, for the country is wonderfully barren. See what it is to be well trained. Horace said to me yesterday, "If every one would kill adders they would come to sting less." I answered: "Of course they would, for there would be fewer." He replied indignantly: "I did not mean that; but the timid adders which run away would be saved, and in time would never sting at all." Natural selection of cowards! LETTER 142. H. FALCONER TO CHARLES DARWIN. (142/1. This refers to the MS. of Falconer's paper "On the American Fossil Elephant of the Regions bordering the Gulf of Mexico (E. Columbi, Falc.)," published in the "Natural History Review," January, 1863, page 43. The section dealing with the bearing of his facts on Darwin's views is at page 77. He insists strongly (page 78) on the "persistence and uniformity of the characters of the molar teeth in the earliest known mammoth, and his most modern successor." Nevertheless, he adds that the "inferences I draw from these facts are not opposed to one of the leading propositions of Darwin's theory." These admissions were the more satisfactory since, as Falconer points out (page 77), "I have been included by him in the category of those who have vehemently maintained the persistence of specific characters.") 21, Park Crescent, Portland Place, N.W., September 24th [1862]. Do not be frightened at the enclosure. I wish to set myself right by you before I go to press. I am bringing out a heavy memoir on elephants--an omnium gatherum affair, with observations on the fossil and recent species. One section is devoted to the persistence in time of the specific characters of the mammoth. I trace him from before the Glacial period, through it and after it, unchangeable and unchanged as far as the organs of digestion (teeth) and locomotion are concerned. Now, the Glacial period was no joke: it would have made ducks and drakes of your dear pigeons and doves. With all my shortcomings, I have such a sincere and affectionate regard for you and such admiration of your work, that I should be pained to find that I had expressed my honest convictions in a way that would be open to any objection by you. The reasoning may be very stupid, but I believe that the observation is sound. Will you, therefore, look over the few pages which I have sent, and tell me whether you find any flaw, or whether you think I should change the form of expression? You have been so unhandsomely and uncandidly dealt with by a friend of yours and mine that I should be sorry to find myself in the position of an opponent to you, and more particularly with the chance of making a fool of myself. I met your brother yesterday, who tells me you are coming to town. I hope you will give me a hail. I long for a jaw with you, and have much to speak to you about. You will have seen the eclaircissement about the Eocene monkeys of England. By a touch of the conjuring wand they have been metamorphosed--a la Darwin--into Hyracotherian pigs. (142/2. "On the Hyracotherian Character of the Lower Molars of the supposed Macacus from the Eocene Sand of Kyson, Suffolk." "Ann. Mag. Nat. Hist." Volume X., 1862, page 240. In this note Owen stated that the teeth which he had named Macacus ("Ann. Mag." 1840, page 191) most probably belonged to Hyracotherium cuniculus. See "A Catalogue of British Fossil Vertebrata," A.S. Woodward and C.D. Sherborn, 1890, under Hyracotherium, page 356; also Zittel's "Handbuch der Palaeontologie" Abth. I., Bd. IV., Leipzig, 1891-93, page 703.) Would you believe it? This even is a gross blunder. They are not pigs. LETTER 143. TO HUGH FALCONER. Down, October 1st [1862]. On my return home yesterday I found your letter and MS., which I have read with extreme interest. Your note and every word in your paper are expressed with the same kind feeling which I have experienced from you ever since I have had the happiness of knowing you. I value scientific praise, but I value incomparably higher such kind feeling as yours. There is not a single word in your paper to which I could possibly object: I should be mad to do so; its only fault is perhaps its too great kindness. Your case seems the most striking one which I have met with of the persistence of specific characters. It is very much the more striking as it relates to the molar teeth, which differ so much in the species of the genus, and in which consequently I should have expected variation. As I read on I felt not a little dumbfounded, and thought to myself that whenever I came to this subject I should have to be savage against myself; and I wondered how savage you would be. I trembled a little. My only hope was that something could be made out of the bog N. American forms, which you rank as a geographical race; and possibly hereafter out of the Sicilian species. Guess, then, my satisfaction when I found that you yourself made a loophole (143/1. This perhaps refers to a passage ("N.H. Review," 1863, page 79) in which Falconer allows the existence of intermediate forms along certain possible lines of descent. Falconer's reference to the Sicilian elephants is in a note on page 78; the bog-elephant is mentioned on page 79.), which I never, of course, could have guessed at; and imagine my still greater satisfaction at your expressing yourself as an unbeliever in the eternal immutability of species. Your final remarks on my work are too generous, but have given me not a little pleasure. As for criticisms, I have only small ones. When you speak of "moderate range of variation" I cannot but think that you ought to remind your readers (though I daresay previously done) what the amount is, including the case of the American bog-mammoth. You speak of these animals as having been exposed to a vast range of climatal changes from before to after the Glacial period. I should have thought, from analogy of sea-shells, that by migration (or local extinction when migration not possible) these animals might and would have kept under nearly the same climate. A rather more important consideration, as it seems to me, is that the whole proboscidean group may, I presume, be looked at as verging towards extinction: anyhow, the extinction has been complete as far as Europe and America are concerned. Numerous considerations and facts have led me in the "Origin" to conclude that it is the flourishing or dominant members of each order which generally give rise to new races, sub-species, and species; and under this point of view I am not at all surprised at the constancy of your species. This leads me to remark that the sentence at the bottom of page [80] is not applicable to my views (143/2. See Falconer at the bottom of page 80: it is the old difficulty--how can variability co-exist with persistence of type? In our copy of the letter the passage is given as occurring on page 60, a slip of the pen for page 80.), though quite applicable to those who attribute modification to the direct action of the conditions of life. An elephant might be more individually variable than any known quadruped (from the effects of the conditions of life or other innate unknown causes), but if these variations did not aid the animal in better resisting all hostile influences, and therefore making it increase in numbers, there would be no tendency to the preservation and accumulation of such variations--i.e. to the formation of a new race. As the proboscidean group seems to be from utterly unknown causes a failing group in many parts of the world, I should not have anticipated the formation of new races. You make important remarks versus Natural Selection, and you will perhaps be surprised that I do to a large extent agree with you. I could show you many passages, written as strongly as I could in the "Origin," declaring that Natural Selection can do nothing without previous variability; and I have tried to put equally strongly that variability is governed by many laws, mostly quite unknown. My title deceives people, and I wish I had made it rather different. Your phyllotaxis (143/3. Falconer, page 80: "The law of Phyllotaxis...is nearly as constant in its manifestation as any of the physical laws connected with the material world.") will serve as example, for I quite agree that the spiral arrangement of a certain number of whorls of leaves (however that may have primordially arisen, and whether quite as invariable as you state), governs the limits of variability, and therefore governs what Natural Selection can do. Let me explain how it arose that I laid so much stress on Natural Selection, and I still think justly. I came to think from geographical distribution, etc., etc., that species probably change; but for years I was stopped dead by my utter incapability of seeing how every part of each creature (a woodpecker or swallow, for instance) had become adapted to its conditions of life. This seemed to me, and does still seem, the problem to solve; and I think Natural Selection solves it, as artificial selection solves the adaptation of domestic races for man's use. But I suspect that you mean something further,--that there is some unknown law of evolution by which species necessarily change; and if this be so, I cannot agree. This, however, is too large a question even for so unreasonably long a letter as this. Nevertheless, just to explain by mere valueless conjectures how I imagine the teeth of your elephants change, I should look at the change as indirectly resulting from changes in the form of the jaws, or from the development of tusks, or in the case of the primigenius even from correlation with the woolly covering; in all cases Natural Selection checking the variation. If, indeed, an elephant would succeed better by feeding on some new kinds of food, then any variation of any kind in the teeth which favoured their grinding power would be preserved. Now, I can fancy you holding up your hands and crying out what bosh! To return to your concluding sentence: far from being surprised, I look at it as absolutely certain that very much in the "Origin" will be proved rubbish; but I expect and hope that the framework will stand. (143/4. Falconer, page 80: "He [Darwin] has laid the foundations of a great edifice: but he need not be surprised if, in the progress of erection, the superstructure is altered by his successors...") I had hoped to have called on you on Monday evening, but was quite knocked up. I saw Lyell yesterday morning. He was very curious about your views, and as I had to write to him this morning I could not help telling him a few words on your views. I suppose you are tired of the "Origin," and will never read it again; otherwise I should like you to have the third edition, and would gladly send it rather than you should look at the first or second edition. With cordial thanks for your generous kindness. LETTER 144. J.D. HOOKER TO CHARLES DARWIN. Royal Gardens, Kew, November 7th, 1862. I am greatly relieved by your letter this morning about my Arctic essay, for I had been conjuring up some egregious blunder (like the granitic plains of Patagonia).. Certes, after what you have told me of Dawson, he will not like the letter I wrote to him days ago, in which I told him that it was impossible to entertain a strong opinion against the Darwinian hypothesis without its giving rise to a mental twist when viewing matters in which that hypothesis was or might be involved. I told him I felt that this was so with me when I opposed you, and that all minds are subject to such obliquities!--the Lord help me, and this to an LL.D. and Principal of a College! I proceeded to discuss his Geology with the effrontery of a novice; and, thank God, I urged the very argument of your letter about evidence of subsidence--viz., not all submerged at once, and glacial action being subaerial and not oceanic. Your letter hence was a relief, for I felt I was hardly strong enough to have launched out as I did to a professed geologist. (144/1. [On the subject of the above letter, see one of earlier date by Sir J.D. Hooker (November 2nd, 1862) given in the present work (Letter 354) with Darwin's reply (Letter 355).]) LETTER 145. TO HUGH FALCONER. Down, November 14th [1862]. I have read your paper (145/1. "On the disputed Affinity of the Mammalian Genus Plagiaulax, from the Purbeck beds."--"Quart. Journ. Geol. Soc." Volume XVIII., page 348, 1862.) with extreme interest, and I thank you for sending it, though I should certainly have carefully read it, or anything with your name, in the Journal. It seems to me a masterpiece of close reasoning: although, of course, not a judge of such subjects, I cannot feel any doubt that it is conclusive. Will Owen answer you? I expect that from his arrogant view of his own position he will not answer. Your paper is dreadfully severe on him, but perfectly courteous, and polished as the finest dagger. How kind you are towards me: your first sentence (145/2. "One of the most accurate observers and original thinkers of our time has discoursed with emphatic eloquence on the Imperfection of the Geological Record.") has pleased me more than perhaps it ought to do, if I had any modesty in my composition. By the way, after reading the first whole paragraph, I re-read it, not for matter, but for style; and then it suddenly occurred to me that a certain man once said to me, when I urged him to publish some of his miscellaneous wealth of knowledge, "Oh, he could not write,--he hated it," etc. You false man, never say that to me again. Your incidental remark on the remarkable specialisation of Plagiaulax (145/3. "If Plagiaulax be regarded through the medium of the view advocated with such power by Darwin, through what a number of intermediate forms must not the genus have passed before it attained the specialised condition in which the fossils come before us!") (which has stuck in my gizzard ever since I read your first paper) as bearing on the number of preceding forms, is quite new to me, and, of course, is in accordance to my notions a most impressive argument. I was also glad to be reminded of teeth of camel and tarsal bones. (145/4. Op. cit. page 353. A reference to Cuvier's instance "of the secret relation between the upper canine-shaped incisors of the camel and the bones of the tarsus.") Descent from an intermediate form, Ahem! Well, all I can say is that I have not been for a long time more interested with a paper than with yours. It gives me a demoniacal chuckle to think of Owen's pleasant countenance when he reads it. I have not been in London since the end of September; when I do come I will beat up your quarters if I possibly can; but I do not know what has come over me. I am worse than ever in bearing any excitement. Even talking of an evening for less than two hours has twice recently brought on such violent vomiting and trembling that I dread coming up to London. I hear that you came out strong at Cambridge (145/5. Prof. Owen, in a communication to the British Association at Cambridge (1862) "On a tooth of Mastodon from the Tertiary marls, near Shanghai," brought forward the case of the Australian Mastodon as a proof of the remarkable geographical distribution of the Proboscidia. In a subsequent discussion he frankly abandoned it, in consequence of the doubts then urged regarding its authenticity. (See footnote, page 101, in Falconer's paper "On the American Fossil Elephant," "Nat. Hist. Review," 1863.)), and am heartily glad you attacked the Australian Mastodon. I never did or could believe in him. I wish you would read my little Primula paper in the "Linnean Journal," Volume VI. Botany (No. 22), page 77 (I have no copy which I can spare), as I think there is a good chance that you may have observed similar cases. This is my real hobby-horse at present. I have re-tested this summer the functional difference of the two forms in Primula, and find all strictly accurate. If you should know of any cases analogous, pray inform me. Farewell, my good and kind friend. LETTER 146. TO J.D. HOOKER. (146/1. The following letter is interesting in connection with a letter addressed to Sir J.D. Hooker, March 26th, 1862, No. 136, where the value of Natural Selection is stated more strongly by Sir Joseph than by Darwin. It is unfortunate that Sir Joseph's letter, to which this is a reply, has not been found.) Down, November 20th [1862]. Your last letter has interested me to an extraordinary degree, and your truly parsonic advice, "some other wise and discreet person," etc., etc., amused us not a little. I will put a concrete case to show what I think A. Gray believes about crossing and what I believe. If 1,000 pigeons were bred together in a cage for 10,000 years their number not being allowed to increase by chance killing, then from mutual intercrossing no varieties would arise; but, if each pigeon were a self-fertilising hermaphrodite, a multitude of varieties would arise. This, I believe, is the common effect of crossing, viz., the obliteration of incipient varieties. I do not deny that when two marked varieties have been produced, their crossing will produce a third or more intermediate varieties. Possibly, or probably, with domestic varieties, with a strong tendency to vary, the act of crossing tends to give rise to new characters; and thus a third or more races, not strictly intermediate, may be produced. But there is heavy evidence against new characters arising from crossing wild forms; only intermediate races are then produced. Now, do you agree thus far? if not, it is no use arguing; we must come to swearing, and I am convinced I can swear harder than you, therefore I am right. Q.E.D. If the number of 1,000 pigeons were prevented increasing not by chance killing, but by, say, all the shorter-beaked birds being killed, then the WHOLE body would come to have longer beaks. Do you agree? Thirdly, if 1,000 pigeons were kept in a hot country, and another 1,000 in a cold country, and fed on different food, and confined in different-size aviary, and kept constant in number by chance killing, then I should expect as rather probable that after 10,000 years the two bodies would differ slightly in size, colour, and perhaps other trifling characters; this I should call the direct action of physical conditions. By this action I wish to imply that the innate vital forces are somehow led to act rather differently in the two cases, just as heat will allow or cause two elements to combine, which otherwise would not have combined. I should be especially obliged if you would tell me what you think on this head. But the part of your letter which fairly pitched me head over heels with astonishment, is that where you state that every single difference which we see might have occurred without any selection. I do and have always fully agreed; but you have got right round the subject, and viewed it from an entirely opposite and new side, and when you took me there I was astounded. When I say I agree, I must make the proviso, that under your view, as now, each form long remains adapted to certain fixed conditions, and that the conditions of life are in the long run changeable; and second, which is more important, that each individual form is a self-fertilising hermaphrodite, so that each hair-breadth variation is not lost by intercrossing. Your manner of putting the case would be even more striking than it is if the mind could grapple with such numbers--it is grappling with eternity--think of each of a thousand seeds bringing forth its plant, and then each a thousand. A globe stretching to the furthest fixed star would very soon be covered. I cannot even grapple with the idea, even with races of dogs, cattle, pigeons, or fowls; and here all admit and see the accurate strictness of your illustration. Such men as you and Lyell thinking that I make too much of a Deus of Natural Selection is a conclusive argument against me. Yet I hardly know how I could have put in, in all parts of my book, stronger sentences. The title, as you once pointed out, might have been better. No one ever objects to agriculturalists using the strongest language about their selection, yet every breeder knows that he does not produce the modification which he selects. My enormous difficulty for years was to understand adaptation, and this made me, I cannot but think, rightly, insist so much on Natural Selection. God forgive me for writing at such length; but you cannot tell how much your letter has interested me, and how important it is for me with my present book in hand to try and get clear ideas. Do think a bit about what is meant by direct action of physical conditions. I do not mean whether they act; my facts will throw some light on this. I am collecting all cases of bud-variations, in contradistinction to seed-variations (do you like this term, for what some gardeners call "sports"?); these eliminate all effects of crossing. Pray remember how much I value your opinion as the clearest and most original I ever get. I see plainly that Welwitschia (146/2. Sir Joseph's great paper on Welwitschia mirabilis was published in the "Linn. Soc. Trans." 1863.) will be a case of Barnacles. I have another plant to beg, but I write on separate paper as more convenient for you to keep. I meant to have said before, as an excuse for asking for so much from Kew, that I have now lost TWO seasons, by accursed nurserymen not having right plants, and sending me the wrong instead of saying that they did not possess. LETTER 147. TO J.D. HOOKER. Down, 24th [November, 1862]. I have just received enclosed for you, and I have thought that you would like to read the latter half of A. Gray's letter to me, as it is political and nearly as mad as ever in our English eyes. You will see how the loss of the power of bullying is in fact the sore loss to the men of the North from disunion. I return with thanks Bates' letter, which I was glad to see. It was very good of you writing to him, for he is evidently a man who wants encouragement. I have now finished his paper (but have read nothing else in the volume); it seems to me admirable. To my mind the act of segregation of varieties into species was never so plainly brought forward, and there are heaps of capital miscellaneous observations. I hardly know why I am a little sorry, but my present work is leading me to believe rather more in the direct action of physical conditions. I presume I regret it, because it lessens the glory of Natural Selection, and is so confoundedly doubtful. Perhaps I shall change again when I get all my facts under one point of view, and a pretty hard job this will be. (147/1. This paragraph was published in "Life and Letters," II., page 390. It is not clear why a belief in "direct action" should diminish the glory of Natural Selection, since the changes so produced must, like any other variations, pass through the ordeal of the survival of the fittest. On the whole question of direct action see Mr. Adam Sedgwick's "Presidential Address to the Zoological Section of the British Association," 1899.) LETTER 148. TO H.W. BATES. Down, November 25th [1862?]. I should think it was not necessary to get a written agreement. (148/1. Mr. Bates' book, "A Naturalist on the Amazons," was published in 1863.) I have never had one from Murray. I suppose you have a letter with terms; if not, I should think you had better ask for one to prevent misunderstandings. I think Sir C. Lyell told me he had not any formal agreements. I am heartily glad to hear that your book is progressing. Could you find me some place, even a footnote (though these are in nine cases out of ten objectionable), where you could state, as fully as your materials permit, all the facts about similar varieties pairing,--at a guess how many you caught, and how many now in your collection? I look at this fact as very important; if not in your book, put it somewhere else, or let me have cases. I entirely agree with you on the enormous advantage of thoroughly studying one group. I really have no criticism to make. (148/2. Mr. Bates' paper on mimetic butterflies was read before the Linnean Society, November 21st, 1861, and published in the "Linn. Soc. Trans." XXIII., 1862, page 495, under the title of "Contributions to an Insect Fauna of the Amazon Valley.") Style seems to me very good and clear; but I much regret that in the title or opening passage you did not blow a loud trumpet about what you were going to show. Perhaps the paper would have been better more divided into sections with headings. Perhaps you might have given somewhere rather more of a summary on the progress of segregation of varieties, and not referred your readers to the descriptive part, excepting such readers as wanted minute detail. But these are trifles: I consider your paper as a most admirable production in every way. Whenever I come to variation under natural conditions (my head for months has been exclusively occupied with domestic varieties), I shall have to study and re-study your paper, and no doubt shall then have to plague you with questions. I am heartily glad to hear that you are well. I have been compelled to write in a hurry; so excuse me. LETTER 149. TO T.H. HUXLEY. Down, December 7th [1862]. I was on the point of adding to an order to Williams & Norgate for your Lectures (149/1. "A Course of Six Lectures to Working Men," published in six pamphlets by Hardwicke, and later as a book. See Letter 156.) when they arrived, and much obliged I am. I have read them with interest, and they seem to me very good for this purpose and capitally written, as is everything which you write. I suppose every book nowadays requires some pushing, so that if you do not wish these lectures to be extensively circulated, I suppose they will not; otherwise I should think they would do good and spread a taste for the natural sciences. Anyhow, I have liked them; but I get more and more, I am sorry to say, to care for nothing but Natural History; and chiefly, as you once said, for the mere species question. I think I liked No. III. the best of all. I have often said and thought that the process of scientific discovery was identical with everyday thought, only with more care; but I never succeeded in putting the case to myself with one-tenth of the clearness with which you have done. I think your second geological section will puzzle your non-scientific readers; anyhow, it has puzzled me, and with the strong middle line, which must represent either a line of stratification or some great mineralogical change, I cannot conceive how your statement can hold good. I am very glad to hear of your "three-year-old" vigour [?]; but I fear, with all your multifarious work, that your book on Man will necessarily be delayed. You bad man; you say not a word about Mrs. Huxley, of whom my wife and self are always truly anxious to hear. P.S. I see in the "Cornhill Magazine" a notice of a work by Cohn, which apparently is important, on the contractile tissue of plants. (149/2. "Ueber contractile Gewebe im Pflanzenreiche." "Abhand. der Schlesischen Gesellschaft fur vaterlandische Cultur," Heft I., 1861.) You ought to have it reviewed. I have ordered it, and must try and make out, if I can, some of the accursed german, for I am much interested in the subject, and experimented a little on it this summer, and came to the conclusion that plants must contain some substance most closely analogous to the supposed diffused nervous matter in the lower animals; or as, I presume, it would be more accurate to say with Cohn, that they have contractile tissue. Lecture VI., page 151, line 7 from top--wetting FEET or bodies? (Miss Henrietta Darwin's criticism.) (149/3. Lecture VI., page 151: Lamarck "said, for example, that the short-legged birds, which live on fish, had been converted into the long-legged waders by desiring to get the fish without wetting their feet." Their criticisms on Lectures IV. and VI. are on a separate piece of undated paper, and must belong to a letter of later date; only three lectures were published by December 7th, 1862.) Lecture IV., page 89--Atavism. You here and there use atavism = inheritance. Duchesne, who, I believe, invented the word, in his Strawberry book confined it, as every one has since done, to resemblance to grandfather or more remote ancestor, in contradistinction to resemblance to parents. LETTER 150. TO JOHN SCOTT. (150/1. The following is the first of a series of letters addressed to the late John Scott, of which the major part is given in our Botanical chapters. We have been tempted to give this correspondence fully not only because of its intrinsic scientific interest, but also because they are almost the only letters which show Darwin in personal relation with a younger man engaged in research under his supervision.) [1862?] To the best of my judgment, no subject is so important in relation to theoretical natural science, in several respects, and likewise in itself deserving investigation, as the effects of changed or unnatural conditions, or of changed structure on the reproductive system. Under this point of view the relation of well-marked but undoubted varieties in fertilising each other requires far more experiments than have been tried. See in the "Origin" the brief abstract of Gartner on Verbascum and Zea. Mr. W. Crocker, lately foreman at Kew and a very good observer, is going at my suggestion to work varieties of hollyhock. (150/2. Altheae species. These experiments seem not to have been carried out.) The climate would be too cold, I suppose, for varieties of tobacco. I began on cabbages, but immediately stopped from early shedding of their pollen causing too much trouble. Your knowledge would suggest some [plants]. On the same principle it would be well to test peloric flowers with their own pollen, and with pollen of regular flowers, and try pollen of peloric on regular flowers--seeds being counted in each case. I have now got one seedling from many crosses of a peloric Pelargonium by peloric pollen; I have two or three seedlings from a peloric flower by pollen of regular flower. I have ordered a peloric Antirrhinum (150/3. See "Variation of Animals and Plants," Edition I., Volume II., page 70.) and the peloric Gloxinia, but I much fear I shall never have time to try them. The Passiflora cases are truly wonderful, like the Crinum cases (see "Origin"). (150/4. "Origin," Edition VI., page 238.) I have read in a German paper that some varieties of potatoes (name not given) cannot be fertilised by [their] own pollen, but can by pollen of other varieties: well worth trying. Again, fertility of any monster flower, which is pretty regularly produced; I have got the wonderful Begonia frigida (150/5. The species on which Sir J.D. Hooker wrote in the "Gardeners' Chronicle," February 25th, 1860. See "Life and Letters," II., page 275.) from Kew, but doubt whether I have heat to set its seeds. If an unmodified Celosia could be got, it would be well to test with the modified cockscomb. There is a variation of columbine [Aquilegia] with simple petals without nectaries, etc., etc. I never could think what to try; but if one could get hold of a long-cultivated plant which crossed with a distinct species and yielded a very small number of seeds, then it would be highly good to test comparatively the wild parent-form and its varying offspring with this third species: for instance, if a polyanthus would cross with some species of Primula, then to try a wild cowslip with it. I believe hardly any primulas have ever been crossed. If we knew and could get the parent of the carnation (150/6. Dianthus caryophyllus, garden variety.), it would be very good for this end. Any member of the Lythraceae raised from seed ought to be well looked after for dimorphism. I have wonderful facts, the result of experiment, on Lythrum salicaria. LETTER 151. TO JOHN SCOTT. Down, December 11th [1862]. I have read your paper with much interest. (151/1. "On the Nature and Peculiarities of the Fern-spore." "Bot. Soc. Edin." Read June 12th, 1862.) You ask for remarks on the matter, which is alone really important. Shall you think me impertinent (I am sure I do not mean to be so) if I hazard a remark on the style, which is of more importance than some think? In my opinion (whether or no worth much) your paper would have been much better if written more simply and less elaborated--more like your letters. It is a golden rule always to use, if possible, a short old Saxon word. Such a sentence as "so purely dependent is the incipient plant on the specific morphological tendency" does not sound to my ears like good mother-English--it wants translating. Here and there you might, I think, have condensed some sentences. I go on the plan of thinking every single word which can be omitted without actual loss of sense as a decided gain. Now perhaps you will think me a meddling intruder: anyhow, it is the advice of an old hackneyed writer who sincerely wishes you well. Your remark on the two sexes counteracting variability in product of the one is new to me. (151/2. Scott (op. cit., page 214): "The reproductive organs of phoenogams, as is well-known, are always products of two morphologically distinct organs, the stamens producing the pollen, the carpels producing the ovules...The embryo being in this case the modified resultant of two originally distinct organs, there will necessarily be a greater tendency to efface any individual peculiarities of these than would have been the case had the embryo been the product of a single organ." A different idea seems to have occurred to Mr. Darwin, for in an undated letter to Scott he wrote: "I hardly know what to say on your view of male and female organs and variability. I must think more over it. But I was amused by finding the other day in my portfolio devoted to bud-variation a slip of paper dated June, 1860, with some such words as these, 'May not permanence of grafted buds be due to the two sexual elements derived from different parts not having come into play?' I had utterly forgotten, when I read your paper that any analogous notion had ever passed through my mind--nor can I now remember, but the slip shows me that it had." It is interesting that Huxley also came to a conclusion differing from Scott's; and, curiously enough, Darwin confused the two views, for he wrote to Scott (December 19th): "By an odd chance, reading last night some short lectures just published by Prof. Huxley, I find your observation, independently arrived at by him, on the confluence of the two sexes causing variability." Professor Huxley's remarks are in his "Lectures to Working Men on our Knowledge, etc." No. 4, page 90: "And, indeed, I think that a certain amount of variation from the primitive stock is the necessary result of the method of sexual propagation itself; for inasmuch as the thing propagated proceeds from two organisms of different sexes and different makes and temperaments, and, as the offspring is to be either of one sex or the other, it is quite clear that it cannot be an exact diagonal of the two, or it would be of no sex at all; it cannot be an exact intermediate form between that of each of its parents--it must deviate to one side or the other.") But I cannot avoid thinking that there is something unknown and deeper in seminal generation. Reflect on the long succession of embryological changes in every animal. Does a bud ever produce cotyledons or embryonic leaves? I have been much interested by your remark on inheritance at corresponding ages; I hope you will, as you say, continue to attend to this. Is it true that female Primula plants always produce females by parthenogenesis? (151/3. It seems probable that Darwin here means vegetative reproduction.) If you can answer this I should be glad; it bears on my Primula work. I thought on the subject, but gave up investigating what had been observed, because the female bee by parthenogenesis produces males alone. Your paper has told me much that in my ignorance was quite new to me. Thanks about P. scotica. If any important criticisms are made on the Primula to the Botanical Society, I should be glad to hear them. If you think fit, you may state that I repeated the crossing experiments on P. sinensis and cowslip with the same result this spring as last year--indeed, with rather more marked difference in fertility of the two crosses. In fact, had I then proved the Linum case, I would not have wasted time in repetition. I am determined I will at once publish on Linum... I was right to be cautious in supposing you in error about Siphocampylus (no flowers were enclosed). I hope that you will make out whether the pistil presents two definite lengths; I shall be astounded if it does. I do not fully understand your objections to Natural Selection; if I do, I presume they would apply with full force to, for instance, birds. Reflect on modification of Arab-Turk horse into our English racehorse. I have had the satisfaction to tell my publisher to send my "Journal" and "Origin" to your address. I suspect, with your fertile mind, you will find it far better to experiment on your own choice; but if, on reflection, you would like to try some which interest me, I should be truly delighted, and in this case would write in some detail. If you have the means to repeat Gartner's experiments on variations of Verbascum or on maize (see the "Origin"), such experiments would be pre-eminently important. I could never get variations of Verbascum. I could suggest an experiment on potatoes analogous with the case of Passiflora; even the case of Passiflora, often as it has been repeated, might be with advantage repeated. I have worked like a slave (having counted about nine thousand seeds) on Melastoma, on the meaning of the two sets of very different stamens, and as yet have been shamefully beaten, and I now cry for aid. I could suggest what I believe a very good scheme (at least, Dr. Hooker thought so) for systematic degeneration of culinary plants, and so find out their origin; but this would be laborious and the work of years. LETTER 152. TO J.D. HOOKER. Down, 12th [December, 1862]. My good old Friend-- How kind you have been to give me so much of your time! Your letter is of real use, and has been and shall be well considered. I am much pleased to find that we do not differ as much as I feared. I begin my book with saying that my chief object is to show the inordinate scale of variation; I have especially studied all sorts of variations of the individual. On crossing I cannot change; the more I think, the more reason I have to believe that my conclusion would be agreed to by all practised breeders. I also greatly doubt about variability and domestication being at all necessarily correlative, but I have touched on this in "Origin." Plants being identical under very different conditions has always seemed to me a very heavy argument against what I call direct action. I think perhaps I will take the case of 1,000 pigeons (152/1. See Letter 146.) to sum up my volume; I will not discuss other points, but, as I have said, I shall recur to your letter. But I must just say that if sterility be allowed to come into play, if long-beaked be in the least degree sterile with short-beaked, my whole case is altered. By the way, my notions on hybridity are becoming considerably altered by my dimorphic work. I am now strongly inclined to believe that sterility is at first a selected quality to keep incipient species distinct. If you have looked at Lythrum you will see how pollen can be modified merely to favour crossing; with equal readiness it could be modified to prevent crossing. It is this which makes me so much interested with dimorphism, etc. (152/2. This gives a narrow impression of Darwin's interest in dimorphism. The importance of his work was (briefly put) the proof that sterility has no necessary connection with specific difference, but depends on sexual differentiation independent of racial differences. See "Life and Letters," III., page 296. His point of view that sterility is a selected quality is again given in a letter to Huxley ("Life and Letters," II., page 384), but was not upheld in his later writings (see "Origin of Species," Edition VI., page 245). The idea of sterility being a selected quality is interesting in connection with Romanes' theory of physiological selection. (See Letters 209-214.)) One word more. When you pitched me head over heels by your new way of looking at the back side of variation, I received assurance and strength by considering monsters--due to law: horribly strange as they are, the monsters were alive till at least when born. They differ at least as much from the parent as any one mammal from another. I have just finished a long, weary chapter on simple facts of variation of cultivated plants, and am now refreshing myself with a paper on Linum for the Linnean Society. LETTER 153. TO W.B. TEGETMEIER. (153/1. The following letter also bears on the question of the artificial production of sterility.) Down, 27th [December, 1862]. The present plan is to try whether any existing breeds happen to have acquired accidentally any degree of sterility; but to this point hereafter. The enclosed MS. will show what I have done and know on the subject. Please at some future time carefully return the MS. to me. If I were going to try again, I would prefer Turbit with Carrier or Dragon. I will suggest an analogous experiment, which I have had for two years in my experimental book with "be sure and try," but which, as my health gets yearly weaker and weaker and my other work increases, I suppose I shall never try. Permit me to add that if 5 pounds would cover the expenses of the experiment, I should be delighted to give it, and you could publish the result if there be any result. I crossed the Spanish cock (your bird) and white Silk hen and got plenty of eggs and chickens; but two of them seemed to be quite sterile. I was then sadly overdone with work, but have ever since much reproached myself that I did not preserve and carefully test the procreative power of these hens. Now, if you are inclined to get a Spanish cock and a couple of white Silk hens, I shall be most grateful to hear whether the offspring breed well: they will prove, I think, not hardy; if they should prove sterile, which I can hardly believe, they will anyhow do for the pot. If you do try this, how would it do to put a Silk cock to your curious silky Cochin hen, so as to get a big silk breed; it would be curious if you could get silky fowl with bright colours. I believe a Silk hen crossed by any other breed never gives silky feathers. A cross from Silk cock and Cochin Silk hen ought to give silky feathers and probably bright colours. I have been led lately from experiments (not published) on dimorphism to reflect much on sterility from hybridism, and partially to change the opinion given in "Origin." I have now letters out enquiring on the following point, implied in the experiment, which seems to me well worth trying, but too laborious ever to be attempted. I would ask every pigeon and fowl fancier whether they have ever observed, in the same breed, a cock A paired to a hen B which did not produce young. Then I would get cock A and match it to a hen of its nearest blood; and hen B to its nearest blood. I would then match the offspring of A (viz., a, b, c, d, e) to the offspring of B (viz., f, g, h, i, j), and all those children which were fertile together should be destroyed until I found one--say a, which was not quite fertile with--say, i. Then a and i should be preserved and paired with their parents A and B, so as to try and get two families which would not unite together; but the members WITHIN each family being fertile together. This would probably be quite hopeless; but he who could effect this would, I believe, solve the problem of sterility from hybridism. If you should ever hear of individual fowls or pigeons which are sterile together, I should be very grateful to hear of the case. It is a parallel case to those recorded of a man not impotent long living with a woman who remained childless; the husband died, and the woman married again and had plenty of children. Apparently (by no means certainly) this first man and woman were dissimilar in their sexual organisation. I conceive it possible that their offspring (if both had married again and both had children) would be sexually dissimilar, like their parents, or sterile together. Pray forgive my dreadful writing; I have been very unwell all day, and have no strength to re-write this scrawl. I am working slowly on, and I suppose in three or four months shall be ready. I am sure I do not know whether any human being could understand or read this shameful scrawl. LETTER 154. TO T.H. HUXLEY. Down, December, 28th [1862]. I return enclosed: if you write, thank Mr. Kingsley for thinking of letting me see the sound sense of an Eastern potentate. (154/1. Kingsley's letter to Huxley, dated December 20th, 1862, contains a story or parable of a heathen Khan in Tartary who was visited by a pair of proselytising Moollahs. The first Moollah said: "Oh! Khan, worship my God. He is so wise that he made all things." But Moollah No. 2 won the day by pointing out that his God is "so wise that he makes all things make themselves.") All that I said about the little book (154/2. The six "Lectures to Working Men," published in six pamphlets and in book-form in 1863. Mr. Huxley considered that Mr. Darwin's argument required the production by man's selection of breeds which should be mutually infertile, and thus resemble distinct species physiologically as well as morphologically.) is strictly my opinion; it is in every way excellent, and cannot fail to do good the wider it is circulated. Whether it is worth your while to give up time to it is another question for you alone to decide; that it will do good for the subject is beyond all question. I do not think a dunce exists who could not understand it, and that is a bold saying after the extent to which I have been misunderstood. I did not understand what you required about sterility: assuredly the facts given do not go nearly so far. We differ so much that it is no use arguing. To get the degree of sterility you expect in recently formed varieties seems to me simply hopeless. It seems to me almost like those naturalists who declare they will never believe that one species turns into another till they see every stage in process. I have heard from Tegetmeier, and have given him the result of my crosses of the birds which he proposes to try, and have told him how alone I think the experiment could be tried with the faintest hope of success--namely, to get, if possible, a case of two birds which when paired were unproductive, yet neither impotent. For instance, I had this morning a letter with a case of a Hereford heifer, which seemed to be, after repeated trials, sterile with one particular and far from impotent bull, but not with another bull. But it is too long a story--it is to attempt to make two strains, both fertile, and yet sterile when one of one strain is crossed with one of the other strain. But the difficulty...would be beyond calculation. As far as I see, Tegetmeier's plan would simply test whether two existing breeds are now in any slight degree sterile; which has already been largely tested: not that I dispute the good of re-testing. LETTER 155. TO HUGH FALCONER. (155/1. The original letter is dated "December 10th," but this must, we think, be a slip of the pen for January 10th. It contains a reference to No. VI. of the "Lectures to Working Men" which, as Mr. Leonard Huxley is good enough to inform us, was not delivered until December 15th, and therefore could not have been seen by Mr. Darwin on December 10th. The change of date makes comprehensible the reference to Falconer's paper "On the American Fossil Elephant of the Regions bordering the Gulf of Mexico (E. Columbi, Falc.)," which appeared in the January number of the "Natural History Review." It is true that he had seen advanced sheets of Falconer's paper ("Life and Letters," II., page 389), but the reference here is to the complete paper. In the present volume we have thought it right to give some expression to the attitude of Darwin towards Owen. Professor Owen's biographer has clearly felt the difficulty of making a statement on Owen's attitude towards Darwinism, and has ("Life of Sir Richard Owen," Volume II., page 92) been driven to adopt the severe indictment contained in the "Origin of Species," Edition VI., page xviii. Darwin was by no means alone in his distrust of Owen; and to omit altogether a reference to the conduct which led up to the isolation of Owen among his former friends and colleagues would be to omit a part of the history of science of the day. And since we cannot omit to notice Darwin's point of view, it seems right to give the facts of a typical case illustrating the feeling with which he regarded Owen. This is all the more necessary since the recently published biography of Sir R. Owen gives no hint, as far as we are aware, of even a difference of opinion with other scientific men. The account which Falconer gives in the above-mentioned paper in the "Nat. Hist. Review" (January, 1863) would be amusing if the matter were less serious. In 1857 Falconer described ("Quart. Journ. Geol. Soc." XIII.) a new species of fossil elephant from America, to which he gave the name Elephas Columbi, a designation which was recognised and adopted by Continental writers. In 1858 (Brit. Assoc. Leeds) Owen made use of the name "Elephas texianus," Blake" for the species which Falconer had previously named E. Columbi, but without referring to Falconer's determination; he gave no authority, "thus by the established usage in zoology producing it as his own." In 1861 Owen in his Palaeontology, 2nd edition, 1861, describes the elephant as E. texianus, Blake. To Mr. Blake's name is appended an asterisk which refers to a footnote to Bollaert's "Antiquities of S. America," 2nd edition. According to Falconer (page 46) no second edition of Bollaert had appeared at the time of writing (August, 1862), and in the first edition (1860) he was "unable to detect the occurrence of the name even, of E. texianus, anywhere throughout the volume"; though Bollaert mentions the fact that he had deposited, in the British Museum, the tooth of a fossil elephant from Texas. In November, 1861, Blake wrote a paper in the "Geologist" in which the new elephant no longer bears his own name as authority, but is described as "Elephas texianus, Owen, E. Columbi, Falconer." Finally, in another paper the name of Owen is dropped and the elephant is once more his own. As Falconer remarks, "the usage of science does not countenance such accommodating arrangements, when the result is to prejudice a prior right." It may be said, no doubt, that the question who first described a given species is a petty one; but this view has a double edge, and applies most strongly to those who neglect the just claims of their predecessors. Down, January 5th [1863]. I finished your Elephant paper last night, and you must let me express my admiration at it. (155/2. "On the American Fossil Elephant of the Regions bordering the Gulf of Mexico (E. Columbi, Falc.), etc." "Nat. Hist. Rev." 1863, page 81. (Cf. Letter to Lyell. "Life and Letters," II., page 389; also "Origin," Edition VI., page 306.) See Letter 143.) All the points strike me as admirably worked out, and very many most interesting. I was particularly struck with your remarks on the character of the ancient Mammalian Fauna of N. America (155/3. Falconer, page 62. This passage is marked in Darwin's copy.); it agrees with all I fancied was the case, namely a temporary irruption of S. American forms into N. America, and conversely, I chuckled a little over the specimen of M. Andium "hesitating" between the two groups. (155/4. In speaking of the characters of Mastodon Andium, Falconer refers to a former paper by himself ("Quart. Journ. Geol. Soc." Volume XIII. 1857, page 313), in which he called attention "to the exceptional character of certain specimens of M. Andium, as if hesitating between [the groups] Tetralophodon and Trilophodon" (ibid., page 100).) I have been assured by Mr. Wallace that abundant Mastodon remains have been found at Timor, and that is rather close to Australia. I rejoice that you have smashed that case. (155/5. In the paper in the "Nat. Hist. Review" (loc. cit.) Falconer writes: "It seems more probable that some unintentional error has got mixed up with the history of this remarkable fossil; and until further confirmatory evidence is adduced, of an unimpeachable character, faith cannot be reposed in the reality of the asserted Australian Mastodon" (page 101).) It is indeed a grand paper. I will say nothing more about your allusions to me, except that they have pleased me quite as much in print as in MS. You must have worked very hard; the labour must have been extreme, but I do hope that you will have health and strength to go on. You would laugh if you could see how indignant all Owen's mean conduct about E. Columbi made me. (155/6. See Letter 157.) I did not get to sleep till past 3 o'clock. How well you lash him, firmly and severely, with unruffled temper, as if you were performing a simple duty. The case is come to such a pass, that I think every man of science is bound to show his feelings by some overt act, and I shall watch for a fitting opportunity. P.S.--I have kept back for a day the enclosed owing to the arrival of your most interesting letter. I knew it was a mere chance whether you could inform me on the points required; but no one other person has so often responded to my miscellaneous queries. I believe I have now in my greenhouse L. trigynum (155/7. Linum trigynum.), which came up from seed purchased as L. flavum, from which it is wholly different in foliage. I have just sent in a paper on Dimorphism of Linum to the Linnean Society (155/8. "On the Existence of the Forms, and on their reciprocal Sexual Relation, in several species of the genus Linum.--"Journ. Linn. Soc." Volume VII., page 69, 1864.), and so I do not doubt your memory is right about L. trigynum: the functional difference in the two forms of Linum is really wonderful. I assure you I quite long to see you and a few others in London; it is not so much the eczema which has taken the epidermis a dozen times clean off; but I have been knocked up of late with extraordinary facility, and when I shall be able to come up I know not. I particularly wish to hear about the wondrous bird: the case has delighted me, because no group is so isolated as Birds. I much wish to hear when we meet which digits are developed; when examining birds two or three years ago, I distinctly remember writing to Lyell that some day a fossil bird would be found with the end of wing cloven, i.e. the bastard-wing and other part, both well developed. Thanks for Von Martius, returned by this post, which I was glad to see. Poor old Wagner (Probably Johann Andreas Wagner, author of "Zur Feststellung des Artbegriffes, mit besonderer Bezugnahme auf die Ansichten von Nathusius, Darwin, Is. Geoffroy and Agassiz," "Munchen Sitzungsb." (1861), page 301, and of numerous papers on zoological and palaeozoological subjects.) always attacked me in a proper spirit, and sent me two or three little brochures, and I thanked him cordially. The Germans seem much stirred up on the subject. I received by the same post almost a little volume on the "Origin." I cannot work above a couple of hours daily, and this plays the deuce with me. P.S. 2nd.--I have worked like a slave and been baffled like a slave in trying to make out the meaning of two very different sets of stamens in some Melastomaceae. (155/9. Several letters on the Melastomaceae occur in our Botanical section.) I must tell you one fact. I counted 9,000 seeds, one by one, from my artificially fertilised pods. There is something very odd, but I am as yet beaten. Plants from two pollens grow at different rates! Now, what I want to know is, whether in individuals of the same species, growing together, you have ever noticed any difference in the position of the pistil or in the size and colour of the stamens? LETTER 156. TO T.H. HUXLEY. Down, December 18th [1862]. I have read Nos. IV, and V. (156/1. "On our Knowledge of the Causes of the Phenomena of Organic Nature," being six Lectures to Working Men delivered at the Museum of Practical Geology by Prof. Huxley, 1863. These lectures, which were given once a week from November 10th, 1862, onwards, were printed from the notes of Mr. J.A. Mays, a shorthand writer, who asked permission to publish them on his own account; Mr. Huxley stating in a prefatory "Notice" that he had no leisure to revise the lectures.) They are simply perfect. They ought to be largely advertised; but it is very good in me to say so, for I threw down No. IV. with this reflection, "What is the good of writing a thundering big book, when everything is in this green little book, so despicable for its size?" In the name of all that is good and bad, I may as well shut up shop altogether. You put capitally and most simply and clearly the relation of animals and plants to each other at page 122. Be careful about Fantails: their tail-feathers are fixed in a radiating position, but they can depress and elevate them. I remember in a pigeon-book seeing withering contempt expressed at some naturalist for not knowing this important point! Page 111 (156/2. The reference is to the original little green paper books in which the lectures first appeared; the paging in the bound volume dated 1863 is slightly different. The passage here is, "...If you couple a male and female hybrid...the result is that in ninety-nine cases out of a hundred you will get no offspring at all." Darwin maintains elsewhere that Huxley, from not knowing the botanical evidence, made too much of this point. See "Life and Letters," II., page 384.) seems a little too strong--viz., ninety-nine out of a hundred, unless you except plants. Page 118: You say the answer to varieties when crossed being at all sterile is "absolutely a negative." (156/3. Huxley, page 112: "Can we find any approximation to this [sterility of hybrids] in the different races known to be produced by selective breeding from a common stock? Up to the present time the answer to that question is absolutely a negative one.") Do you mean to say that Gartner lied, after experiments by the hundred (and he a hostile witness), when he showed that this was the case with Verbascum and with maize (and here you have selected races): does Kolreuter lie when he speaks about the varieties of tobacco? My God, is not the case difficult enough, without its being, as I must think, falsely made more difficult? I believe it is my own fault--my d--d candour: I ought to have made ten times more fuss about these most careful experiments. I did put it stronger in the third edition of the "Origin." If you have a new edition, do consider your second geological section: I do not dispute the truth of your statement; but I maintain that in almost every case the gravel would graduate into the mud; that there would not be a hard, straight line between the mass of gravel and mud; that the gravel, in crawling inland, would be separated from the underlying beds by oblique lines of stratification. A nice idea of the difficulty of Geology your section would give to a working man! Do show your section to Ramsay, and tell him what I say; and if he thinks it a fair section for a beginner I am shut up, and "will for ever hold my tongue." Good-night. LETTER 157. TO T.H. HUXLEY. Down, [January] 10th [1863]. You will be weary of notes from me about the little book of yours. It is lucky for me that I expressed, before reading No. VI. (157/1. "Lectures to Working Men," No. VI., is a critical examination of the position of the "Origin of Species" in relation to the complete theory of the "causes of the phenomena of organic nature."), my opinion of its absolute excellence, and of its being well worth wide distribution and worth correction (not that I see where you could improve), if you thought it worth your valuable time. Had I read No. VI., even a rudiment of modesty would, or ought to, have stopped me saying so much. Though I have been well abused, yet I have had so much praise, that I have become a gourmand, both as to capacity and taste; and I really did not think that mortal man could have tickled my palate in the exquisite manner with which you have done the job. So I am an old ass, and nothing more need be said about this. I agree entirely with all your reservations about accepting the doctrine, and you might have gone further with further safety and truth. Of course I do not wholly agree about sterility. I hate beyond all things finding myself in disagreement with any capable judge, when the premises are the same; and yet this will occasionally happen. Thinking over my former letter to you, I fancied (but I now doubt) that I had partly found out the cause of our disagreement, and I attributed it to your naturally thinking most about animals, with which the sterility of the hybrids is much more conspicuous than the lessened fertility of the first cross. Indeed, this could hardly be ascertained with mammals, except by comparing the products of [their] whole life; and, as far as I know, this has only been ascertained in the case of the horse and ass, which do produce fewer offspring in [their] lifetime than in pure breeding. In plants the test of first cross seems as fair as test of sterility of hybrids. And this latter test applies, I will maintain to the death, to the crossing of varieties of Verbascum, and varieties, selected varieties, of Zea. (157/2. See Letter 156.) You will say Go to the Devil and hold your tongue. No, I will not hold my tongue; for I must add that after going, for my present book, all through domestic animals, I have come to the conclusion that there are almost certainly several cases of two or three or more species blended together and now perfectly fertile together. Hence I conclude that there must be something in domestication,--perhaps the less stable conditions, the very cause which induces so much variability,--which eliminates the natural sterility of species when crossed. If so, we can see how unlikely that sterility should arise between domestic races. Now I will hold my tongue. Page 143: ought not "Sanscrit" to be "Aryan"? What a capital number the last "Natural History Review" is! That is a grand paper by Falconer. I cannot say how indignant Owen's conduct about E. Columbi has made me. I believe I hate him more than you do, even perhaps more than good old Falconer does. But I have bubbled over to one or two correspondents on this head, and will say no more. I have sent Lubbock a little review of Bates' paper in "Linn. Transact." (157/3. The unsigned review of Mr. Bates' work on mimetic butterflies appeared in the "Nat. Hist. Review" (1863), page 219.) which L. seems to think will do for your "Review." Do inaugurate a great improvement, and have pages cut, like the Yankees do; I will heap blessings on your head. Do not waste your time in answering this. LETTER 158. TO JOHN LUBBOCK [LORD AVEBURY]. Down, January 23rd [1863]. I have no criticism, except one sentence not perfectly smooth. I think your introductory remarks very striking, interesting, and novel. (158/1. "On the Development of Chloeon (Ephemera) dimidiatum, Part I. By John Lubbock. "Trans. Linn. Soc." Volume XXIV., pages 61-78, 1864 [Read January 15th, 1863].) They interested me the more, because the vaguest thoughts of the same kind had passed through my head; but I had no idea that they could be so well developed, nor did I know of exceptions. Sitaris and Meloe (158/2. Sitaris and Meloe, two genera of coleopterous insects, are referred to by Lubbock (op. cit., pages 63-64) as "perhaps...the most remarkable cases...among the Coleoptera" of curious and complicated metamorphoses.) seem very good. You have put the whole case of metamorphosis in a new light; I dare say what you remark about poverty of fresh-water is very true. (158/3. "We cannot but be struck by the poverty of the fresh-water fauna when compared with that of the ocean" (op. cit., page 64).) I think you might write a memoir on fresh-water productions. I suggest that the key-note is that land-productions are higher and have advantage in general over marine; and consequently land-productions have generally been modified into fresh-water productions, instead of marine productions being directly changed into fresh-water productions, as at first seems more probable, as the chance of immigration is always open from sea to rivers and ponds. My talk with you did me a deal of good, and I enjoyed it much. LETTER 159. TO J.D. HOOKER. Down, January 13th [1863]. I send a very imperfect answer to [your] question, which I have written on foreign paper to save you copying, and you can send when you write to Thomson in Calcutta. Hereafter I shall be able to answer better your question about qualities induced in individuals being inherited; gout in man--loss of wool in sheep (which begins in the first generation and takes two or three to complete); probably obesity (for it is rare with poor); probably obesity and early maturity in short-horn cattle, etc., etc. LETTER 160. TO A. DE CANDOLLE. Down, January 14th [1863]. I thank you most sincerely for sending me your Memoir. (160/1. Etude sur l'Espece a l'occasion d'une revision de la Famille des Cupuliferes. "Biblioth. Univ. (Arch. des Sc. Phys. et Nat.)," Novembre 1862.) I have read it with the liveliest interest, as is natural for me; but you have the art of making subjects, which might be dry, run easily. I have been fairly astonished at the amount of individual variability in the oaks. I never saw before the subject in any department of nature worked out so carefully. What labour it must have cost you! You spoke in one letter of advancing years; but I am very sure that no one would have suspected that you felt this. I have been interested with every part; though I am so unfortunate as to differ from most of my contemporaries in thinking that the vast continental extensions (160/2. See Letters 47, 48.) of Forbes, Heer, and others are not only advanced without sufficient evidence, but are opposed to much weighty evidence. You refer to my work in the kindest and most generous spirit. I am fully satisfied at the length in belief to which you go, and not at all surprised at the prudent reservations which you make. I remember well how many years it cost me to go round from old beliefs. It is encouraging to me to observe that everyone who has gone an inch with me, after a period goes a few more inches or even feet. But the great point, as it seems to me, is to give up the immutability of specific forms; as long as they are thought immutable, there can be no real progress in "Epiontology." (160/3. See De Candolle, loc. cit., page 67: he defines "Epiontologie" as the study of the distribution and succession of organised beings from their origin up to the present time. At present Epiontology is divided into geography and palaeontology, "mais cette division trop inegale et a limites bien vagues disparaitra probablement.") It matters very little to any one except myself, whether I am a little more or less wrong on this or that point; in fact, I am sure to be proved wrong in many points. But the subject will have, I am convinced, a grand future. Considering that birds are the most isolated group in the animal kingdom, what a splendid case is this Solenhofen bird-creature with its long tail and fingers to its wings! I have lately been daily and hourly using and quoting your "Geographical Botany" in my book on "Variation under Domestication." LETTER 161. TO HORACE DOBELL. Down, February 16th [1863]. Absence from home and consequent idleness are the causes that I have not sooner thanked you for your very kind present of your Lectures. (161/1. "On the Germs and Vestiges of Disease," (London) 1861.) Your reasoning seems quite satisfactory (though the subject is rather beyond my limit of thought and knowledge) on the V.M.F. not being "a given quantity." (161/2. "It has been too common to consider the force exhibited in the operations of life (the V.M.F.) as a given quantity, to which no accessions can be made, but which is apportioned to each living being in quantity sufficient for its necessities, according to some hidden law" (op. cit., page 41.) And I can see that the conditions of life must play a most important part in allowing this quantity to increase, as in the budding of a tree, etc. How far these conditions act on "the forms of organic life" (page 46) I do not see clearly. In fact, no part of my subject has so completely puzzled me as to determine what effect to attribute to (what I vaguely call) the direct action of the conditions of life. I shall before long come to this subject, and must endeavour to come to some conclusion when I have got the mass of collected facts in some sort of order in my mind. My present impression is that I have underrated this action in the "Origin." I have no doubt when I go through your volume I shall find other points of interest and value to me. I have already stumbled on one case (about which I want to consult Mr. Paget)--namely, on the re-growth of supernumerary digits. (161/3. See Letters 178, 270.) You refer to "White on Regeneration, etc., 1785." I have been to the libraries of the Royal and the Linnean Societies, and to the British Museum, where the librarians got out your volume and made a special hunt, and could discover no trace of such a book. Will you grant me the favour of giving me any clue, where I could see the book? Have you it? if so, and the case is given briefly, would you have the great kindness to copy it? I much want to know all particulars. One case has been given me, but with hardly minute enough details, of a supernumerary little finger which has already been twice cut off, and now the operation will soon have to be done for the third time. I am extremely much obliged for the genealogical table; the fact of the two cousins not, as far as yet appears, transmitting the peculiarity is extraordinary, and must be given by me. LETTER 162. TO C. LYELL. [February 17th, 1863.] The same post that brought the enclosed brought Dana's pamphlet on the same subject. (162/1. The pamphlet referred to was published in "Silliman's Journal," Volume XXV., 1863, pages 65 and 71, also in the "Annals and Magazine of Natural History," Volume XI., pages 207-14, 1863: "On the Higher Subdivisions in the Classification of Mammals." In this paper Dana maintains the view that "Man's title to a position by himself, separate from the other mammals in classification, appears to be fixed on structural as well as physical grounds" (page 210). His description is as follows:-- I. ARCHONTIA (vel DIPODA) Man (alone). II. MEGASTHENA. III. MICROSTHENA. Quadrumana. Cheiroptera. Carnivora. Insectivora. Herbivora. Rodentia. Mutilata. Bruta (Edentata). IV. OOTICOIDEA. Marsupialia. Monotremata.) The whole seems to me utterly wild. If there had not been the foregone wish to separate men, I can never believe that Dana or any one would have relied on so small a distinction as grown man not using fore-limbs for locomotion, seeing that monkeys use their limbs in all other respects for the same purpose as man. To carry on analogous principles (for they are not identical, in crustacea the cephalic limbs are brought close to mouth) from crustacea to the classification of mammals seems to me madness. Who would dream of making a fundamental distinction in birds, from fore-limbs not being used at all in [some] birds, or used as fins in the penguin, and for flight in other birds? I get on slowly with your grand work, for I am overwhelmed with odds and ends and letters. LETTER 163. TO J.D. HOOKER. (163/1. The following extract refers to Owen's paper in the "Linn. Soc. Journal," June, 1857, in which the classification of the Mammalia by cerebral characters was proposed. In spite of the fact that men and apes are placed in distinct Sub-Classes, Owen speaks (in the foot-note of which Huxley made such telling effect) of the determination of the difference between Homo and Pithecus as the anatomist's difficulty. (See Letter 119.)) July 5th, 1857. What a capital number of the "Linnean Journal!" Owen's is a grand paper; but I cannot swallow Man making a division as distinct from a chimpanzee as an Ornithorhynchus from a horse; I wonder what a chimpanzee would say to this? (163/2. According to Owen the sub-class Archencephala contains only the genus Homo: the Gyrencephala contains both chimpanzee and horse, the Lyencephala contains Ornithorhynchus.) LETTER 164. TO T.H. HUXLEY. Down [February?] 26th, 1863. I have just finished with very great interest "Man's Place." (164/1. "Evidence as to Man's Place in Nature," 1863 (preface dated January 1863).) I never fail to admire the clearness and condensed vigour of your style, as one calls it, but really of your thought. I have no criticisms; nor is it likely that I could have. But I think you could have added some interesting matter on the character or disposition of the young ourangs which have been kept in France and England. I should have thought you might have enlarged a little on the later embryological changes in man and on his rudimentary structure, tail as compared with tail of higher monkeys, intermaxillary bone, false ribs, and I daresay other points, such as muscles of ears, etc., etc. I was very much struck with admiration at the opening pages of Part II. (and oh! what a delicious sneer, as good as a dessert, at page 106) (164/2. Huxley, op. cit., page 106. After saying that "there is but one hypothesis regarding the origin of species of animals in general which has any scientific existence--that propounded by Mr. Darwin," and after a few words on Lamarck, he goes on: "And though I have heard of the announcement of a formula touching 'the ordained continuous becoming of organic forms,' it is obvious that it is the first duty of a hypothesis to be intelligible, and that a qua-qua-versal proposition of this kind, which may be read backwards or forwards, or sideways, with exactly the same amount of significance, does not really exist, though it may seem to do so." The "formula" in question is Owen's.): but my admiration is unbounded at pages 109 to 112. I declare I never in my life read anything grander. Bacon himself could not have charged a few paragraphs with more condensed and cutting sense than you have done. It is truly grand. I regret extremely that you could not, or did not, end your book (not that I mean to say a word against the Geological History) with these pages. With a book, as with a fine day, one likes it to end with a glorious sunset. I congratulate you on its publication; but do not be disappointed if it does not sell largely: parts are highly scientific, and I have often remarked that the best books frequently do not get soon appreciated: certainly large sale is no proof of the highest merit. But I hope it may be widely distributed; and I am rejoiced to see in your note to Miss Rhadamanthus (164/3. This refers to Mr. Darwin's daughter (now Mrs. Litchfield), whom Mr. Huxley used to laugh at for the severity of her criticisms.) that a second thousand is called for of the little book. What a letter that is of Owen's in the "Athenaeum" (164/4. A letter by Owen in the "Athenaeum," February 21st, 1863, replying to strictures on his treatment of the brain question, which had appeared in Lyell's "Antiquity of Man."); how cleverly he will utterly muddle and confound the public. Indeed he quite muddled me, till I read again your "concise statement" (164/5. This refers to a section (pages 113-18) in "Man's Place in Nature," headed "A succinct History of the Controversy respecting the Cerebral Structure of Man and the Apes." Huxley follows the question from Owen's attempt to classify the mammalia by cerebral characters, published by the "Linn. Soc." in 1857, up to his revival of the subject at the Cambridge meeting of the British Association in 1862. It is a tremendous indictment of Owen, and seems to us to conclude not unfittingly with a citation from Huxley's article in the "Medical Times," October 11th, 1862. Huxley here points out that special investigations have been made into the question at issue "during the last two years" by Allen Thomson, Rolleston, Marshall, Flower, Schroeder van der Kolk and Vrolik, and that "all these able and conscientious observers" have testified to the accuracy of his statements, "while not a single anatomist, great or small, has supported Professor Owen." He sums up the case once more, and concludes: "The question has thus become one of personal veracity. For myself I will accept no other issue than this, grave as it is, to the present controversy.") (which is capitally clear), and then I saw that my suspicion was true that he has entirely changed his ground to size of Brain. How candid he shows himself to have taken the slipped Brain! (164/6. Owen in the "Athenaeum," February 21st, 1863, admits that in the brain which he used in illustration of his statements "the cerebral hemispheres had glided forward and apart behind so as to expose a portion of the cerebellum.") I am intensely curious to see whether Lyell will answer. (164/7. Lyell's answer was in the "Athenaeum" March 7th, 1863.) Lyell has been, I fear, rather rash to enter on a subject on which he of course knows nothing by himself. By heavens, Owen will shake himself, when he sees what an antagonist he has made for himself in you. With hearty admiration, Farewell. I am fearfully disappointed at Lyell's excessive caution (164/8. In the "Antiquity of Man": see "Life and Letters," III., page 8.) in expressing any judgment on Species or [on the] origin of Man. LETTER 165. TO JOHN SCOTT. Down, March 6th, 1863. I thank you for your criticisms on the "Origin," and which I have not time to discuss; but I cannot help doubting, from your expression of an "INNATE...selective principle," whether you fully comprehend what is meant by Natural Selection. Certainly when you speak of weaker (i.e. less well adapted) forms crossing with the stronger, you take a widely different view from what I do on the struggle for existence; for such weaker forms could not exist except by the rarest chance. With respect to utility, reflect that 99/100ths part of the structure of each being is due to inheritance of formerly useful structures. Pray read what I have said on "correlation." Orchids ought to show us how ignorant we are of what is useful. No doubt hundreds of cases could be advanced of which no explanation could be offered; but I must stop. Your letter has interested me much. I am very far from strong, and have great fear that I must stop all work for a couple of months for entire rest, and leave home. It will be ruin to all my work. LETTER 166. TO J.D. HOOKER. Down, April 23rd [1863]. The more I think of Falconer's letter (166/1. Published in the "Athenaeum" April 4th, 1863, page 459. The writer asserts that Lyell did not make it clear that certain material made use of in the "Antiquity of Man" was supplied by the original work of Mr. Prestwich and himself. (See "Life and Letters," III., page 19.)) the more grieved I am; he and Prestwich (the latter at least must owe much to the "Principles") assume an absurdly unwarrantable position with respect to Lyell. It is too bad to treat an old hero in science thus. I can see from a note from Falconer (about a wonderful fossil Brazilian Mammal, well called Meso- or Typo-therium) that he expects no sympathy from me. He will end, I hope, by being sorry. Lyell lays himself open to a slap by saying that he would come to show his original observations, and then not distinctly doing so; he had better only have laid claim, on this one point of man, to verification and compilation. Altogether, I much like Lyell's letter. But all this squabbling will greatly sink scientific men. I have seen a sneer already in the "Times." LETTER 167. TO H.W. BATES. At Rev. C. Langton, Hartfield, Tunbridge Wells, April 30th [1863]. You will have received before this the note which I addressed to Leicester, after finishing Volume I., and you will have received copies of my little review (167/1. "Nat. Hist. Review," 1863, page 219. A review of Bates' paper on Mimetic Butterflies.) of your paper...I have now finished Volume II., and my opinion remains the same--that you have written a truly admirable work (167/2. "The Naturalist on the Amazons," 1863.), with capital original remarks, first-rate descriptions, and the whole in a style which could not be improved. My family are now reading the book, and admire it extremely; and, as my wife remarks, it has so strong an air of truthfulness. I had a letter from a person the other day, unknown to you, full of praise of the book. I do hope it may get extensively heard of and circulated; but to a certain extent this, I think, always depends on chance. I suppose the clicking noise of surprise made by the Indian is that which the end of the tongue, applied to the palate of the mouth and suddenly withdrawn, makes? I have not written since receiving your note of April 20th, in which you confided in me and told me your prospects. I heartily wish they were better, and especially more certain; but with your abilities and powers of writing it will be strange if you cannot add what little you require for your income. I am glad that you have got a retired and semi-rural situation. What a grand ending you give to your book, contrasting civilisation and wild life! I quite regret that I have finished it: every evening it was a real treat to me to have my half-hour in the grand Amazonian forest, and picture to myself your vivid descriptions. There are heaps of facts of value to me in a natural history point of view. It was a great misfortune that you were prevented giving the discussion on species. But you will, I hope, be able to give your views and facts somewhere else. LETTER 168. TO J.D. HOOKER. Down, May 15th [1863]. Your letter received this morning interested me more than even most of your letters, and that is saying a good deal. I must scribble a little on several points. About Lyell and species--you put the whole case, I do believe, when you say that he is "half-hearted and whole-headed." (168/1. Darwin's disappointment with the cautious point of view taken up by Lyell in the "Antiquity of Man" is illustrated in the "Life and Letters," III., pages 11, 13. See also Letter 164, page 239.) I wrote to A. Gray that, when I saw such men as Lyell and he refuse to judge, it put me in despair, and that I sometimes thought I should prefer that Lyell had judged against modification of species rather than profess inability to decide; and I left him to apply this to himself. I am heartily rejoiced to hear that you intend to try to bring L. and F. (168/2. Falconer claimed that Lyell had not "done justice to the part he took in resuscitating the cave question." See "Life and Letters," III., page 14.) together again; but had you not better wait till they are a little cooled? You will do Science a real good service. Falconer never forgave Lyell for taking the Purbeck bones from him and handing them over to Owen. With respect to island floras, if I understand rightly, we differ almost solely how plants first got there. I suppose that at long intervals, from as far back as later Tertiary periods to the present time, plants occasionally arrived (in some cases, perhaps, aided by different currents from existing currents and by former islands), and that these old arrivals have survived little modified on the islands, but have become greatly modified or become extinct on the continent. If I understand, you believe that all islands were formerly united to continents, and then received all their plants and none since; and that on the islands they have undergone less extinction and modification than on the continent. The number of animal forms on islands, very closely allied to those on continents, with a few extremely distinct and anomalous, does not seem to me well to harmonise with your supposed view of all having formerly arrived or rather having been left together on the island. LETTER 169. TO ASA GRAY. Down, May 31st [1863?]. I was very glad to receive your review (169/1. The review on De Candolle's work on the Oaks (A. Gray's "Scientific Papers," I., page 130).) of De Candolle a week ago. It seems to me excellent, and you speak out, I think, more plainly in favour of derivation of species than hitherto, though doubtfully about Natural Selection. Grant the first, I am easy about the second. Do you not consider such cases as all the orchids next thing to a demonstration against Heer's view of species arising suddenly by monstrosities?--it is impossible to imagine so many co-adaptations being formed all by a chance blow. Of course creationists would cut the enigma. LETTER 170. TO T.H. HUXLEY. June 27th [1863?] What are you doing now? I have never yet got hold of the "Edinburgh Review," in which I hear you are well abused. By the way, I heard lately from Asa Gray that Wyman was delighted at "Man's Place." (170/1. "Evidence as to Man's Place in Nature," by T.H. Huxley, 1863.) I wonder who it is who pitches weakly, but virulently into you, in the "Anthropological Review." How quiet Owen seems! I do at last begin to believe that he will ultimately fall in public estimation. What nonsense he wrote in the "Athenaeum" (170/2. "Athenaeum," March 28th, 1863. See "Life and Letters," III., page 17.) on Heterogeny! I saw in his Aye-Aye (170/3. See Owen in the "Trans. Zool. Soc." Volume V. The sentence referred to seems to be the following (page 95): "We know of no changes in progress in the Island of Madagascar, necessitating a special quest of wood-boring larvae by small quadrupeds of the Lemurine or Sciurine types of organisation.') paper (I think) that he sneers at the manner in which he supposes that we should account for the structure of its limbs; and asks how we know that certain insects had increased in the Madagascar forests. Would it not be a good rebuff to ask him how he knows there were trees at all on the leafless plains of La Plata for his Mylodons to tear down? But I must stop, for if I once begin about [him] there will be no end. I was disappointed in the part about species in Lyell. (170/4. Lyell's "Antiquity of Man." See "Life and Letters," III., page 11.) You and Hooker are the only two bold men. I have had a bad spring and summer, almost constantly very unwell; but I am crawling on in my book on "Variation under Domestication.") LETTER 171. TO C. LYELL. Down, August 14th [1863]. Have you seen Bentham's remarks on species in his address to the Linnean Society? (171/1. Presidential address before the Linnean Society by G. Bentham ("Journ. Proc. Linn. Soc." Volume VII., page xi., 1864).) they have pleased me more than anything I have read for some time. I have no news, for I have not seen a soul for months, and have had a bad spring and summer, but have managed to do a good deal of work. Emma is threatening me to take me to Malvern, and perhaps I shall be compelled, but it is a horrid waste of time; you must have enjoyed North Wales, I should think, it is to me a most glorious country... If you have not read Bates' book (171/2. Henry Walter Bates, "The Naturalist on the River Amazons," 2 volumes, London, 1863. In a letter to Bates, April 18th, 1863, Darwin writes, "It is the best work of natural history travels ever published in England" ("Life and Letters," II., page 381.), I think it would interest you. He is second only to Humboldt in describing a tropical forest. (171/3. Quoted in "Life and Letters," II., page 381.). Talking of reading, I have never got the "Edinburgh" (171/4. The "Geological Evidence of the Antiquity of Man," by Sir Charles Lyell, and works by other authors reviewed in the "Edinburgh Review." Volume CXVIII., July 1863. The writer sums up his criticism as follows: "Glancing at the work of Sir Charles Lyell as a whole, it leaves the impression on our minds that we have been reading an ingenious academical thesis, rather than a work of demonstration by an original writer...There is no argument in it, and only a few facts which have not been stated elsewhere by Sir C. Lyell himself or by others" (loc. cit., page 294).), in which, I suppose, you are cut up. LETTER 172. TO H. FALCONER. December 26th [1863]. Thank you for telling me about the Pliocene mammal, which is very remarkable; but has not Owen stated that the Pliocene badger is identical with the recent? Such a case does indeed well show the stupendous duration of the same form. I have not heard of Suess' pamphlet (172/1. Probably Suess's paper "Ueber die Verschiedenheit und die Aufeinanderfolge der tertiaren Land-faunen in der Niederung von Wien." "Sitz.-Ber. Wien Akad." XLVII., page 306, 1863.), and should much like to learn the title, if it can be procured; but I am on different subjects just at present. I should rather like to see it rendered highly probable that the process of formation of a new species was short compared to its duration--that is, if the process was allowed to be slow and long; the idea is new to me. Heer's view that new species are suddenly formed like monsters, I feel a conviction from many reasons is false. CHAPTER 1.IV.--EVOLUTION, 1864-1869. LETTER 173. TO A.R. WALLACE. Down, January 1st, 1864. I am still unable to write otherwise than by dictation. In a letter received two or three weeks ago from Asa Gray he writes: "I read lately with gusto Wallace's expose of the Dublin man on Bees' cells, etc." (173/1. "Remarks on the Rev. S. Haughton's paper on the Bee's Cell and on the Origin of Species" ("Ann. and Mag. Nat. Hist." XII., 1863, page 303). Prof. Haughton's paper was read before the Natural History Society of Dublin, November 21st, 1862, and reprinted in the "Ann. and Mag. Nat. Hist." XI., 1863, page 415. See Letters 73, 74, 75.) Now, though I cannot read at present, I much want to know where this is published, that I may procure a copy. Further on, Asa Gray says (after speaking of Agassiz's paper on Glaciers in the "Atlantic Magazine" and his recent book entitled "Method of Study"): "Pray set Wallace upon these articles." So Asa Gray seems to think much of your powers of reviewing, and I mention this as it assuredly is laudari a laudato. I hope you are hard at work, and if you are inclined to tell me, I should much like to know what you are doing. It will be many months, I fear, before I shall do anything. LETTER 174. TO J.L.A. DE QUATREFAGES. Down, March 27th [1864?]. I had heard that your work was to be translated, and I heard it with pleasure; but I can take no share of credit, for I am not an active, only an honorary member of the Society. Since writing I have finished with extreme interest to the end your admirable work on metamorphosis. (174/1. Probably "Metamorphoses of Man and the Lower Animals." Translated by H. Lawson, 1864.) How well you are acquainted with the works of English naturalists, and how generously you bestow honour on them! Mr. Lubbock is my neighbour, and I have known him since he was a little boy; he is in every way a thoroughly good man; as is my friend Huxley. It gave me real pleasure to see you notice their works as you have done. LETTER 175. TO T.H. HUXLEY. Down, April 11th [1864]. I am very much obliged for your present of your "Comp. Anatomy." (175/1. "Lectures on the Elements of Comparative Anatomy," 1864.) When strong enough I am sure I shall read it with greatest interest. I could not resist the last chapter, of which I have read a part, and have been much interested about the "inspired idiot." (175/2. In reference to Oken (op. cit., page 282) Huxley says: "I must confess I never read his works without thinking of the epithet of 'inspired idiot' applied to our own Goldsmith.") If Owen wrote the article "Oken" (175/3. The article on Oken in the eighth edition of the "Encyclopaedia Britannica" is signed "R.O.": Huxley wrote to Darwin (April 18th, 1864), "There is not the smallest question that Owen wrote both the article 'Oken' and the 'Archetype' Book" (Huxley's "Life," I., page 250). Mr. Huxley's statements amount to this: (1) Prof. Owen accuses Goethe of having in 1820 appropriated Oken's theory of the skull, and of having given an apocryphal account of how the idea occurred to himself in 1790. (2) in the same article, page 502, Owen stated it to be questionable whether the discoverer of the true theory of the segmental constitution of the skull (i.e. himself) was excited to his labours, or "in any way influenced by the a priori guesses of Oken." On this Huxley writes, page 288: "But if he himself had not been in any way influenced by Oken, and if the 'Programm' [of Oken] is a mere mass of 'a priori guesses,' how comes it that only three years before Mr. Owen could write thus? 'Oken, ce genie profond et penetrant, fut le premier qui entrevit la verite, guide par l'heureuse idee de l'arrangement des os craniens en segments, comme ceux du rachis, appeles vertebres...'" Later on Owen wrote: "Cela servira pour exemple d'une examen scrupuleux des faits, d'une appreciation philosophique de leurs relations et analogies, etc." (From "Principes d'Osteologie comparee, ou Recherches sur l'Archetype," etc., pages 155, 1855). (3) Finally Huxley says, page 289, plainly: "The fact is that, so far from not having been 'in any way influenced' by Oken, Prof. Owen's own contributions to this question are the merest Okenism, remanie.") and the French work on the Archetype (points you do not put quite clearly), he never did a baser act...You are so good a Christian that you will hardly understand how I chuckle over this bit of baseness. I hope you keep well and hearty; I honour your wisdom at giving up at present Society for Science. But, on the other hand, I feel it in myself possible to get to care too much for Natural Science and too little for other things. I am getting better, I almost dare to hope permanently; for my sickness is decidedly less--for twenty-seven days consecutively I was sick many times daily, and lately I was five days free. I long to do a little work again. The magnificent (by far the most magnificent, and too magnificent) compliment which you paid me at the end of your "Origin of Species" (175/4. A title applied to the "Lectures to Working Men," that "green little book" referred to in Letter 156. Speaking of Mr. Darwin's work he says (page 156): "I believe that if you strip it of its theoretical part, it still remains one of the greatest encyclopaedias of biological doctrine that any one man ever brought forth; and I believe that, if you take it as the embodiment of an hypothesis, it is destined to be the guide of biological and psychological speculation for the next three or four generations.') I have met with reprinted from you two or three times lately. LETTER 175A. TO ERASMUS DARWIN. Down, June 30th, 1864. (175A.1. The preceding letter contains a reference to the prolonged period of ill-health which Darwin suffered in 1863 and 1864, and in this connection the present letter is of interest. The Copley Medal was given to him in 1864.) I had not heard a word about the Copley Medal. Please give Falconer my cordial thanks for his interest about me. I enclose the list of everything published by me except a few unimportant papers. Ask Falconer not to mention that I sent the list, as some one might say I had been canvassing, which is an odious imputation. The origin of the Voyage in the "Beagle" was that Fitz-Roy generously offered to give up half his cabin to any one who would volunteer to go as naturalist. Beaufort wrote to Cambridge, and I volunteered. Fitz-Roy never persuaded me to give up the voyage on account of sickness, nor did I ever think of doing so, though I suffered considerably; but I do not believe it was the cause of my subsequent ill-health, which has lost me so many years, and therefore I should not think the sea-sickness was worth notice. It would save you trouble to forward this with my kindest remembrances to Falconer. (176/1. The following letter was the beginning of a correspondence with Mr. B.D. Walsh, whom C.V. Riley describes as "one of the ablest and most thorough entomologists of our time.") LETTER 176. B.D. WALSH TO CHARLES DARWIN. Rock Island, Illinois, U.S., April 29th, 1864. (176/2. The words in square brackets are restorations of parts torn off the original letter.) More than thirty years ago I was introduced to you at your rooms in Christ's College by A.W. Grisebach, and had the pleasure of seeing your noble collection of British Coleoptera. Some years afterwards I became a Fellow of Trinity, and finally gave up my Fellowship rather than go into Orders, and came to this country. For the last five or six years I have been paying considerable attention to the insect fauna of the U.S., some of the fruits of which you will see in the enclosed pamphlets. Allow me to take this opportunity of thanking you for the publication of your "Origin of Species," which I read three years ago by the advice of a botanical friend, though I had a strong prejudice against what I supposed then to be your views. The first perusal staggered me, the second convinced me, and the oftener I read it the more convinced I am of the general soundness of your theory. As you have called upon naturalists that believe in your views to give public testimony of their convictions, I have directed your attention on the outside of one or two of my pamphlets to the particular passages in which [I] have done so. You will please accept these papers from me in token of my respect and admiration. As you may see from the latest of these papers, I [have] recently made the remarkable discover that there [are the] so-called "three sexes" not only in social insects but [also in the] strictly solitary genus Cynips. When is your great work to make its appearance? [I should be] much pleased to receive a few lines from you. LETTER 177. TO B.D. WALSH. Down, October 21st [1864]. Ill-health has prevented me from sooner thanking you for your very kind letter and several memoirs. I have been very much pleased to see how boldly and clearly you speak out on the modification of species. I thank you for giving me the pages of reference; but they were superfluous, for I found so many original and profound remarks that I have carefully looked through all the papers. I hope that your discovery about the Cynips (177/1. "On Dimorphism in the hymenopterous genus Cynips," "Proc. Entom. Soc. Philadelphia," March, 1864. Mr. Walsh's view is that Cynips quercus aciculata is a dimorphous form of Cynips q. spongifica, and occurs only as a female. Cynips q. spongifica also produces spongifica females and males from other galls at a different time of year.) will hold good, for it is a remarkable one, and I for one have often marvelled what could be the meaning of the case. I will lend your paper to my neighbour Mr. Lubbock, who I know is much interested in the subject. Incidentally I shall profit by your remarks on galls. If you have time I think a rather hopeless experiment would be worth trying; anyhow, I should have tried it had my health permitted. It is to insert a minute grain of some organic substance, together with the poison from bees, sand-wasps, ichneumons, adders, and even alkaloid poisons into the tissues of fitting plants for the chance of monstrous growths being produced. (177/2. See "Life and Letters," III., page 346, for an account of experiments attempted in this direction by Mr. Darwin in 1880. On the effects of injuring plant-tissues, see Massart, "La Cicatrisation, etc." in Tome LVII. of the "Memoires Couronnes" of the Brussels Academy.) My health has long been poor, and I have lately suffered from a long illness which has interrupted all work, but I am now recommencing a volume in connection with the "Origin." P.S.--If you write again I should very much like to hear what your life in your new country is. What can be the meaning or use of the great diversity of the external generative organs in your cases, in Bombus, and the phytophagous coleoptera? What can there be in the act of copulation necessitating such complex and diversified apparatus? LETTER 178. TO W.H. FLOWER. Down, July 11th, 1864. I am truly obliged for all the trouble which you have taken for me, and for your very interesting note. I had only vaguely heard it said that frogs had a rudiment of a sixth toe; had I known that such great men had looked to the point I should not have dreamed of looking myself. The rudiment sent to you was from a full-grown frog; so that if these bones are the two cuneiforms they must, I should think, be considered to be in a rudimentary condition. This afternoon my gardener brought in some tadpoles with the hind-legs alone developed, and I looked at the rudiment. At this age it certainly looks extremely like a digit, for the extremity is enlarged like that of the adjoining real toe, and the transverse articulation seems similar. I am sorry that the case is doubtful, for if these batrachians had six toes, I certainly think it would have thrown light on the truly extraordinary strength of inheritance in polydactylism in so many animals, and especially on the power of regeneration in amputated supernumerary digits. (178/1. In the first edition of "Variation under Domestication" the view here given is upheld, but in the second edition (Volume I., page 459) Darwin withdrew his belief that the development of supernumerary digits in man is "a case of reversion to a lowly-organised progenitor provided with more than five digits." See Letters 161, 270.) LETTER 179. TO J.D. HOOKER. Down [October 22nd, 1864]. The Lyells have been here, and were extremely pleasant, but I saw them only occasionally for ten minutes, and when they went I had an awful day [of illness]; but I am now slowly getting up to my former standard. I shall soon be confined to a living grave, and a fearful evil it is. I suppose you have read Tyndall. (179/1. Probably Tyndall "On the Conformation of the Alps" ("Phil. Mag." 1864, page 255).) I have now come round again to Ramsay's view, (179/2. "Phil. Mag." 1864, page 293.) for the third or fourth time; but Lyell says when I read his discussion in the "Elements," I shall recant for the fifth time. (179/3. This refers to a discussion on the "Connection of the predominance of Lakes with Glacial Action" ("Elements," Edition VI., pages 168-74). Lyell adheres to the views expressed in the "Antiquity of Man" (1863) against Ramsay's theory of the origin of lake basins by ice action.) What a capital writer Tyndall is! In your last note you ask what the Bardfield oxlip is. It is P. elatior of Jacq., which certainly looks, when growing, to common eyes different from the common oxlip. I will fight you to the death that as primrose and cowslip are different in appearance (not to mention odour, habitat and range), and as I can now show that, when they cross, the intermediate offspring are sterile like ordinary hybrids, they must be called as good species as a man and a gorilla. I agree that if Scott's red cowslip grew wild or spread itself and did not vary [into] common cowslip (and we have absolutely no proof of primrose or cowslip varying into each other), and as it will not cross with the cowslip, it would be a perfectly good species. The power of remaining for a good long period constant I look at as the essence of a species, combined with an appreciable amount of difference; and no one can say there is not this amount of difference between primrose and oxlip. (PLATE: HUGH FALCONER, 1844. From a photograph by Hill & Adamson.) LETTER 180. HUGH FALCONER TO W. SHARPEY. (180/1. Falconer had proposed Darwin for the Copley Medal of the Royal Society (which was awarded to him in 1864), but being detained abroad, he gave his reasons for supporting Darwin for this honour in a letter to Sharpey, the Secretary of the Royal Society. A copy of the letter here printed seems to have been given to Erasmus Darwin, and by him shown to his brother Charles.) Montauban, October 25th, 1864. Busk and myself have made every effort to be back in London by the 27th inst., but we have been persecuted by mishaps--through the breakdown of trains, diligences, etc., so that we have been sadly put out in our reckoning--and have lost some of the main objects that brought us round by this part of France--none of which were idle or unimportant. Busk started yesterday for Paris from Bruniquel, to make sure of being present at the meeting of the Royal Council on Thursday. He will tell you that there were strong reasons for me remaining behind him. But as I seconded the proposal of Mr. Darwin for the Copley Medal, in default of my presence at the first meeting, I beg that you will express my great regrets to the President and Council at not being there, and that I am very reluctantly detained. I shall certainly be in London (D.V.) by the second meeting on the 3rd proximo. Meanwhile I solicit the favour of being heard, through you, respecting the grounds upon which I seconded Mr. Darwin's nomination for the Copley Medal. Referring to the classified list which I drew up of Mr. Darwin's scientific labours, ranging through the wide field of (1) Geology, (2) Physical Geography, (3) Zoology, (4) physiological Botany, (5) genetic Biology, and to the power with which he has investigated whatever subject he has taken up,--Nullum quod tetigit non ornavit,--I am of opinion that Mr. Darwin is not only one of the most eminent naturalists of his day, but that hereafter he will be regarded as one of the great naturalists of all countries and of all time. His early work on the structure and distribution of coral reefs constitutes an era in the investigation of the subject. As a monographic labour, it may be compared with Dr. Wells' "Essay upon Dew," as original, exhaustive, and complete--containing the closest observation with large and important generalisations. Among the zoologists his monographs upon the Balanidae and Lepadidae, Fossil and Recent, in the Palaeontographical and Ray Societies' publications, are held to be models of their kind. In physiological Botany, his recent researches upon the dimorphism of the genital organs in certain plants, embodied in his papers in the "Linnean Journal," on Primula, Linum, and Lythrum, are of the highest order of importance. They open a new mine of observation upon a field which had been barely struck upon before. The same remark applies to his researches on the structure and various adaptations of the orchideous flower to a definite object connected with impregnation of the plants through the agency of insects with foreign pollen. There has not yet been time for their due influence being felt in the advancement of the science. But in either subject they constitute an advance per saltum. I need not dwell upon the value of his geological researches, which won for him one of the earlier awards of the Wollaston Medal from the Geological Society, the best of judges on the point. And lastly, Mr. Darwin's great essay on the "Origin of Species" by Natural Selection. This solemn and mysterious subject had been either so lightly or so grotesquely treated before, that it was hardly regarded as being within the bounds of legitimate philosophical investigation. Mr. Darwin, after twenty years of the closest study and research, published his views, and it is sufficient to say that they instantly fixed the attention of mankind throughout the civilised world. That the efforts of a single mind should have arrived at success on a subject of such vast scope, and encompassed with such difficulties, was more than could have been reasonably expected, and I am far from thinking that Charles Darwin has made out all his case. But he has treated it with such power and in such a philosophical and truth-seeking spirit, and illustrated it with such an amount of original and collated observation as fairly to have brought the subject within the bounds of rational scientific research. I consider this great essay on genetic Biology to constitute a strong additional claim on behalf of Mr. Darwin for the Copley Medal. (180/2. The following letter (December 3rd, 1864), from Mr. Huxley to Sir J.D. Hooker, is reprinted, by the kind permission of Mr. L. Huxley, from his father's "Life," I., page 255. Sabine's address (from the "Reader") is given in the "Life and Letters," III., page 28. In the "Proceedings of the Royal Society" the offending sentence is slightly modified. It is said, in Huxley's "Life" (loc. cit., note), that the sentence which follows it was introduced to mitigate the effect:-- "I wish you had been at the anniversary meeting and dinner, because the latter was very pleasant, and the former, to me, very disagreeable. My distrust of Sabine is, as you know, chronic; and I went determined to keep careful watch on his address, lest some crafty phrase injurious to Darwin should be introduced. My suspicions were justified, the only part of the address [relating] to Darwin written by Sabine himself containing the following passage: "'Speaking generally and collectively, we have expressly omitted it [Darwin's theory] from the grounds of our award.' "Of course this would be interpreted by everybody as meaning that after due discussion, the council had formally resolved not only to exclude Darwin's theory from the grounds of the award, but to give public notice through the president that they had done so, and, furthermore, that Darwin's friends had been base enough to accept an honour for him on the understanding that in receiving it he should be publicly insulted! "I felt that this would never do, and therefore, when the resolution for printing the address was moved, I made a speech, which I took care to keep perfectly cool and temperate, disavowing all intention of interfering with the liberty of the president to say what he pleased, but exercising my constitutional right of requiring the minutes of council making the award to be read, in order that the Society might be informed whether the conditions implied by Sabine had been imposed or not. "The resolution was read, and of course nothing of the kind appeared. Sabine didn't exactly like it, I believe. Both Busk and Falconer remonstrated against the passage to him, and I hope it will be withdrawn when the address is printed. If not, there will be an awful row, and I for one will show no mercy.") In forming an estimate of the value and extent of Mr. Darwin's researches, due regard ought to be had to the circumstances under which they have been carried out--a pressure of unremitting disease, which has latterly left him not more than one or two hours of the day which he could call his own. LETTER 181. TO HUGH FALCONER. Down, November 4th [1864]. What a good kind friend you are! I know well that this medal must have cost you a deal of trouble. It is a very great honour to me, but I declare the knowledge that you and a few other friends have interested themselves on the subject is the real cream of the enjoyment to me; indeed, it is to me worth far more than many medals. So accept my true and cordial thanks. I hope that I may yet have strength to do a little more work in Natural Science, shaky and old though I be. I have chuckled and triumphed over your postscript about poor M. Brulle and his young pupils (181/1. The following is the postscript in a letter from Falconer to Darwin November 3rd [1864]: "I returned last night from Spain via France. On Monday I was at Dijon, where, while in the Museum, M. Brulle, Professor of Zoology, asked me what was my frank opinion of Charles Darwin's doctrine? He told me in despair that he could not get his pupils to listen to anything from him except a la Darwin! He, poor man, could not comprehend it, and was still unconvinced, but that all young Frenchmen would hear or believe nothing else.") About a week ago I had a nearly similar account from Germany, and at the same time I heard of some splendid converts in such men as Leuckart, Gegenbauer, etc. You may say what you like about yourself, but I look at a man who treats natural history in the same spirit with which you do, exactly as good, for what I believe to be the truth, as a convert. LETTER 182. TO HUGH FALCONER. Down, November 8th [1864]. Your remark on the relation of the award of the medal and the present outburst of bigotry had not occurred to me. It seems very true, and makes me the more gratified to receive it. General Sabine (182/1. See "Life and Letters," III., page 28.) wrote to me and asked me to attend at the anniversary, but I told him it was really impossible. I have never been able to conjecture the cause; but I find that on my good days, when I can write for a couple of hours, that anything which stirs me up like talking for half or even a quarter of an hour, generally quite prostrates me, sometimes even for a long time afterwards. I believe attending the anniversary would possibly make me seriously ill. I should enjoy attending and shaking you and a few of my other friends by the hand, but it would be folly even if I did not break down at the time. I told Sabine that I did not know who had proposed and seconded me for the medal, but that I presumed it was you, or Hooker or Busk, and that I felt sure, if you attended, you would receive the medal for me; and that if none of you attended, that Lyell or Huxley would receive it for me. Will you receive it, and it could be left at my brother's? Again accept my cordial and enduring thanks for all your kindness and sympathy. LETTER 183. TO B.D. WALSH. Down, December 4th [1864]. I have been greatly interested by your account of your American life. What an extraordinary and self-contained life you have led! and what vigour of mind you must possess to follow science with so much ardour after all that you have undergone! I am very much obliged to you for your pamphlet on Geographical Distribution, on Agassiz, etc. (183/1. Mr. Walsh's paper "On certain Entomological Speculations of the New England School of Entomologists" was published in the "Proc. Entomolog. Soc. of Philadelphia," September 1864, page 207.) I am delighted at the manner in which you have bearded this lion in his den. I agree most entirely with all that you have written. What I meant when I wrote to Agassiz to thank him for a bundle of his publications, was exactly what you suppose. (183/2. Namely, that Mr. Darwin, having been abused as an atheist, etc., by other writers, probably felt grateful to a writer who was willing to allow him "a spirit as reverential as his own." ("Methods of Study," Preface, page iv.) I confess, however, I did not fully perceive how he had misstated my views; but I only skimmed through his "Methods of Study," and thought it a very poor book. I am so much accustomed to be utterly misrepresented that it hardly excites my attention. But you really have hit the nail on the head capitally. All the younger good naturalists whom I know think of Agassiz as you do; but he did grand service about glaciers and fish. About the succession of forms, Pictet has given up his whole views, and no geologist now agrees with Agassiz. I am glad that you have attacked Dana's wild notions; [though] I have a great respect for Dana...If you have an opportunity, read in "Trans. Linn. Soc." Bates on "Mimetic Lepidoptera of Amazons." I was delighted with his paper. I have got a notice of your views about the female Cynips inserted in the "Natural History Review" (183/3. "Nat. Hist. Review," January 1865, page 139. A notice by "J.L." (probably Lord Avebury) on Walsh's paper "On Dimorphism in the Hymenopterous Genus Cynips," in the "Proc. Entomolog. Soc. of Philadelphia," March, 1864.): whether the notice will be favourable, I do not know, but anyhow it will call attention to your views... As you allude in your paper to the believers in change of species, you will be glad to hear that very many of the very best men are coming round in Germany. I have lately heard of Hackel, Gegenbauer, F. Muller, Leuckart, Claparede, Alex. Braun, Schleiden, etc. So it is, I hear, with the younger Frenchmen. LETTER 184. TO J.D. HOOKER. Down, January 19th [1865]. It is working hours, but I am trying to take a day's holiday, for I finished and despatched yesterday my Climbing paper. For the last ten days I have done nothing but correct refractory sentences, and I loathe the whole subject like tartar emetic. By the way, I am convinced that you want a holiday, and I think so because you took the devil's name in vain so often in your last note. Can you come here for Sunday? You know how I should like it, and you will be quiet and dull enough here to get plenty of rest. I have been thinking with regret about what you said in one of your later notes, about having neglected to make notes on the gradation of character in your genera; but would it be too late? Surely if you looked over names in series the facts would come back, and you might surely write a fine paper "On the gradation of important characters in the genera of plants." As for unimportant characters, I have made their perfect gradation a very prominent point with respect to the means of climbing, in my paper. I begin to think that one of the commonest means of transition is the same individual plant having the same part in different states: thus Corydalis claviculata, if you look to one leaf, may be called a tendril-bearer; if you look to another leaf it may be called a leaf-climber. Now I am sure I remember some cases with plants in which important parts such as the position of the ovule differ: differences in the spire of leaves on lateral and terminal branches, etc. There was not much in last "Natural History Review" which interested me except colonial floras (184/1. "Nat. Hist. Review," 1865, page 46. A review of Grisebach's "Flora of the British West Indian Islands" and Thwaites' "Enumeratio Plantarum Zeylaniae." The point referred to is given at page 57: "More than half the Flowering Plants belong to eleven Orders in the case of the West Indies, and to ten in that of Ceylon, whilst with but one exception the Ceylon Orders are the same as the West Indian." The reviewer speculates on the meaning of the fact "in relation to the hypothesis of an intertropical cold epoch, such as Mr. Darwin demands for the migration of the Northern Flora to the Southern hemisphere.") and the report on the sexuality of cryptogams. I suppose the former was by Oliver; how extremely curious is the fact of similarity of Orders in the Tropics! I feel a conviction that it is somehow connected with Glacial destruction, but I cannot "wriggle" comfortably at all on the subject. I am nearly sure that Dana makes out that the greatest number of crustacean forms inhabit warmer temperate regions. I have had an enormous letter from Leo Lesquereux (after doubts, I did not think it worth sending you) on Coal Flora: he wrote some excellent articles in "Silliman" again [my] "Origin" views; but he says now after repeated reading of the book he is a convert! But how funny men's minds are! he says he is chiefly converted because my books make the Birth of Christ, Redemption by Grace, etc., plain to him! LETTER 185. TO J.D. HOOKER. Down, February 9th [1865]. I quite agree how humiliating the slow progress of man is, but every one has his own pet horror, and this slow progress or even personal annihilation sinks in my mind into insignificance compared with the idea or rather I presume certainty of the sun some day cooling and we all freezing. To think of the progress of millions of years, with every continent swarming with good and enlightened men, all ending in this, and with probably no fresh start until this our planetary system has been again converted into red-hot gas. Sic transit gloria mundi, with a vengeance... LETTER 186. TO B.D. WALSH. Down, March 27th [1865]. I have been much interested by your letter. I received your former paper on Phytophagic variety (186/1. For "Phytophagic Varieties and Phytophagic Species" see "Proc. Entomolog. Soc. Philadelphia," November 1864, page 403, also December 1865. The part on gradation is summarised at pages 427, 428. Walsh shows that a complete gradation exists between species which are absolutely unaffected by change of food and cases where "difference of food is accompanied by marked and constant differences, either colorational, or structural, or both, in the larva, pupa and imago states."), most of which was new to me. I have since received your paper on willow-galls; this has been very opportune, as I wanted to learn a little about galls. There was much in this paper which has interested me extremely, on gradations, etc., and on your "unity of coloration." (186/2. "Unity of coloration": this expression does not seem to occur in the paper of November 1864, but is discussed at length in that of December 1865, page 209.) This latter subject is nearly new to me, though I collected many years ago some such cases with birds; but what struck me most was when a bird genus inhabits two continents, the two sections sometimes display a somewhat different type of colouring. I should like to hear whether this does not occur with widely ranging insect-genera? You may like to hear that Wichura (186/3. Max Wichura's "Die Bastarde befruchtung im Pflanzenreich, etc:" Breslau 1865. A translation appeared in the "Bibliotheque Universelle," xxiii., page 129: Geneva 1865.) has lately published a book which has quite convinced me that in Europe there is a multitude of spontaneous hybrid willows. Would it not be very interesting to know how the gall-makers behaved with respect to these hybrids? Do you think it likely that the ancestor of Cecidomyia acquired its poison like gnats (which suck men) for no especial purpose (at least not for gall-making)? Such notions make me wish that some one would try the experiments suggested in my former letter. Is it not probable that guest-flies were aboriginally gall-makers, and bear the same relation to them which Apathus probably does to Bombus? (186/4. Apathus (= Psithyrus) lives in the nests of Bombus. These insects are said to be so like humble bees that "they were not distinguished from them by the early entomologists:" Dr. Sharp in "Cambridge Nat. Hist. (Insects," Part II.), page 59.) With respect to dimorphism, you may like to hear that Dr. Hooker tells me that a dioecious parasitic plant allied to Rafflesia has its two sexes parasitic on two distinct species of the same genus of plants; so look out for some such case in the two forms of Cynips. I have posted to you copies of my papers on dimorphism. Leersia (186/5. Leersia oryzoides was for a long time thought to produce only cleistogamic and therefore autogamous flowers. See "Variation of Animals and Plants," Edition II., Volume II., page 69.) does behave in a state of nature in the provoking manner described by me. With respect to Wagner's curious discovery my opinion is worth nothing; no doubt it is a great anomaly, but it does not appear to me nearly so incredible as to you. Remember how allied forms in the Hydrozoa differ in their so-called alternate generations; I follow those naturalists who look at all such cases as forms of gemmation; and a multitude of organisms have this power or traces of this power at all ages from the germ to maturity. With respect to Agassiz's views, there were many, and there are still not a few, who believe that the same species is created on many spots. I wrote to Bates, and he will send you his mimetic paper; and I dare say others: he is a first-rate man. Your case of the wingless insects near the Rocky Mountains is extremely curious. I am sure I have heard of some such case in the Old World: I think on the Caucasus. Would not my argument about wingless insular insects perhaps apply to truly Alpine insects? for would it not be destruction to them to be blown from their proper home? I should like to write on many points at greater length to you, but I have no strength to spare. LETTER 187. TO A.R. WALLACE. Down, September 22nd [1865]. I am much obliged for your extract (187/1. Mr. Wallace had sent Darwin a note about a tufted cock-blackbird, which transmitted the character to some of its offspring.); I never heard of such a case, though such a variation is perhaps the most likely of any to occur in a state of nature, and to be inherited, inasmuch as all domesticated birds present races with a tuft or with reversed feathers on their heads. I have sometimes thought that the progenitor of the whole class must have been a crested animal. Do you make any progress with your journal of travels? I am the more anxious that you should do so as I have lately read with much interest some papers by you on the ourang-outan, etc., in the "Annals," of which I have lately been reading the later volumes. I have always thought that journals of this nature do considerable good by advancing the taste for Natural History: I know in my own case that nothing ever stimulated my zeal so much as reading Humboldt's "Personal Narrative." I have not yet received the last part of the "Linnean Transactions," but your paper (187/2. Probably on the variability and distribution of the butterflies of the Malayan region: "Linn. Soc. Trans." XXV., 1866.) at present will be rather beyond my strength, for though somewhat better, I can as yet do hardly anything but lie on the sofa and be read aloud to. By the way, have you read Tylor and Lecky? (187/3. Tylor, "Early History of Mankind;" Lecky's "Rationalism.") Both these books have interested me much. I suppose you have read Lubbock. (187/4. Lubbock, "Prehistoric Times," page 479: "...the theory of Natural Selection, which with characteristic unselfishness he ascribes unreservedly to Mr. Darwin.") In the last chapter there is a note about you in which I most cordially concur. I see you were at the British Association but I have heard nothing of it except what I have picked up in the "Reader." I have heard a rumour that the "Reader" is sold to the Anthropological Society. If you do not begrudge the trouble of another note (for my sole channel of news through Hooker is closed by his illness) I should much like to hear whether the "Reader" is thus sold. I should be very sorry for it, as the paper would thus become sectional in its tendency. If you write, tell me what you are doing yourself. The only news which I have about the "Origin" is that Fritz Muller published a few months ago a remarkable book (187/5. "Fur Darwin.") in its favour, and secondly that a second French edition is just coming out. LETTER 188. TO F. MULLER. Down, January 11th [1866]. I received your interesting letter of November 5th some little time ago, and despatched immediately a copy of my "Journal of Researches." I fear you will think me troublesome in my offer; but have you the second German edition of the "Origin?" which is a translation, with additions, of the third English edition, and is, I think, considerably improved compared with the first edition. I have some spare copies which are of no use to me, and it would be a pleasure to me to send you one, if it would be of any use to you. You would never require to re-read the book, but you might wish to refer to some passage. I am particularly obliged for your photograph, for one likes to have a picture in one's mind of any one about whom one is interested. I have received and read with interest your paper on the sponge with horny spicula. (188/1. "Ueber Darwinella aurea, einen Schwamm mit sternformigen Hornnadeln."--"Archiv. Mikrosk. Anat." I., page 57, 1866.) Owing to ill-health, and being busy when formerly well, I have for some years neglected periodical scientific literature, and have lately been reading up, and have thus read translations of several of your papers; amongst which I have been particularly glad to read and see the drawings of the metamorphoses of Peneus. (188/2. "On the Metamorphoses of the Prawns," by Dr. Fritz Muller.--"Ann. Mag. Nat. Hist." Volume XIV., page 104 (with plate), 1864. Translated by W.S. Dallas from "Wiegmann's Archiv," 1863 (see also "Facts and Arguments for Darwin," passim, translated by W.S. Dallas: London, 1869).) This seems to me the most interesting discovery in embryology which has been made for years. I am much obliged to you for telling me a little of your plans for the future; what a strange, but to my taste interesting life you will lead when you retire to your estate on the Itajahy! You refer in your letter to the facts which Agassiz is collecting, against our views, on the Amazons. Though he has done so much for science, he seems to me so wild and paradoxical in all his views that I cannot regard his opinions as of any value. LETTER 189. TO A.R. WALLACE. Down, January 22nd, 1866. I thank you for your paper on pigeons (189/1. "On the Pigeons of the Malay Archipelago" (The "Ibis," October, 1865). Mr. Wallace points out (page 366) that "the most striking superabundance of pigeons, as well as of parrots, is confined to the Australo-Malayan sub-region in which...the forest-haunting and fruit-eating mammals, such as monkeys and squirrels, are totally absent." He points out also that monkeys are "exceedingly destructive to eggs and young birds."), which interested me, as everything that you write does. Who would ever have dreamed that monkeys influenced the distribution of pigeons and parrots! But I have had a still higher satisfaction, for I finished your paper yesterday in the "Linnean Transactions." (189/2. "Linn. Soc. Trans." XXV.: a paper on the geographical distribution and variability of the Malayan Papilionidae.) It is admirably done. I cannot conceive that the most firm believer in species could read it without being staggered. Such papers will make many more converts among naturalists than long-winded books such as I shall write if I have strength. I have been particularly struck with your remarks on dimorphism; but I cannot quite understand one point (page 22), (189/3. The passage referred to in this letter as needing further explanation is the following: "The last six cases of mimicry are especially instructive, because they seem to indicate one of the processes by which dimorphic forms have been produced. When, as in these cases, one sex differs much from the other, and varies greatly itself, it may happen that individual variations will occasionally occur, having a distant resemblance to groups which are the objects of mimicry, and which it is therefore advantageous to resemble. Such a variety will have a better chance of preservation; the individuals possessing it will be multiplied; and their accidental likeness to the favoured group will be rendered permanent by hereditary transmission, and each successive variation which increases the resemblance being preserved, and all variations departing from the favoured type having less chance of preservation, there will in time result those singular cases of two or more isolated and fixed forms bound together by that intimate relationship which constitutes them the sexes of a single species. The reason why the females are more subject to this kind of modification than the males is, probably, that their slower flight, when laden with eggs, and their exposure to attack while in the act of depositing their eggs upon leaves, render it especially advantageous for them to have some additional protection. This they at once obtain by acquiring a resemblance to other species which, from whatever cause, enjoy a comparative immunity from persecution." Mr. Wallace has been good enough to give us the following note on the above passage: "The above quotation deals solely with the question of how certain females of the polymorphic species (Papilio Memnon, P. Pammon, and others) have been so modified as to mimic species of a quite distinct section of the genus; but it does not attempt to explain why or how the other very variable types of female arose, and this was Darwin's difficulty. As the letter I wrote in reply is lost, and as it is rather difficult to explain the matter clearly without reference to the coloured figures, I must go into some little detail, and give now what was probably the explanation I gave at the time. The male of Papilio Memnon is a large black butterfly with the nervures towards the margins of the wings bordered with bluish gray dots. It is a forest insect, and the very dark colour renders it conspicuous; but it is a strong flier, and thus survives. To the female, however, this conspicuous mass of colour would be dangerous, owing to her slower flight, and the necessity for continually resting while depositing her eggs on the leaves of the food-plant of the larva. She has accordingly acquired lighter and more varied tints. The marginal gray-dotted stripes of the male have become of a brownish ash and much wider on the fore wings, while the margin of the hind wings is yellowish, with a more defined spot near the anal angle. This is the form most nearly like the male, but it is comparatively rare, the more common being much lighter in colour, the bluish gray of the hind wings being often entirely replaced by a broad band of yellowish white. The anal angle is orange-yellow, and there is a bright red spot at the base of the fore wings. Between these two extremes there is every possible variation. Now, it is quite certain that this varying mixture of brown, black, white, yellow, and red is far less conspicuous amid the ever-changing hues of the forest with their glints of sunshine everywhere penetrating so as to form strong contrasts and patches of light and shade. Hence ALL the females--one at one time and one at another--get SOME protection, and that is sufficient to enable them to live long enough to lay their eggs, when their work is finished. Still, under bad conditions they only just managed to survive, and as the colouring of some of these varying females very much resembled that of the protected butterflies of the P. coon group (perhaps at a time when the tails of the latter were not fully developed) any rudiments of a prolongation of the wing into a tail added to the protective resemblance, and was therefore preserved. The woodcuts of some of these forms in my "Malay Archipelago" (i., page 200) will enable those who have this book at hand better to understand the foregoing explanation."), and should be grateful for an explanation, for I want fully to understand you. How can one female form be selected and the intermediate forms die out, without also the other extreme form also dying out from not having the advantages of the first selected form? for, as I understand, both female forms occur on the same island. I quite agree with your distinction between dimorphic forms and varieties; but I doubt whether your criterion of dimorphic forms not producing intermediate offspring will suffice, for I know of a good many varieties which must be so called that will not blend or intermix, but produce offspring quite like either parent. I have been particularly struck with your remarks on geographical distribution in Celebes. It is impossible that anything could be better put, and would give a cold shudder to the immutable naturalists. And now I am going to ask a question which you will not like. How does your journal get on? It will be a shame if you do not popularise your researches. LETTER 190. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, Sussex, July 2nd, 1866. I have been so repeatedly struck by the utter inability of numbers of intelligent persons to see clearly, or at all, the self-acting and necessary effects of Natural Selection, that I am led to conclude that the term itself, and your mode of illustrating it, however clear and beautiful to many of us, are yet not the best adapted to impress it on the general naturalist public. The two last cases of the misunderstanding are: (1) the article on "Darwin and his Teachings" in the last "Quarterly Journal of Science," which, though very well written and on the whole appreciative, yet concludes with a charge of something like blindness, in your not seeing that Natural Selection requires the constant watching of an intelligent "chooser," like man's selection to which you so often compare it; and (2) in Janet's recent work on the "Materialism of the Present Day," reviewed in last Saturday's "Reader," by an extract from which I see that he considers your weak point to be that you do not see that "thought and direction are essential to the action of Natural Selection." The same objection has been made a score of times by your chief opponents, and I have heard it as often stated myself in conversation. Now, I think this arises almost entirely from your choice of the term "Natural Selection" and so constantly comparing it in its effects to Man's Selection, and also your so frequently personifying nature as "selecting," as "preferring," as "seeking only the good of the species," etc., etc. To the few this is as clear as daylight, and beautifully suggestive, but to many it is evidently a stumbling-block. I wish, therefore, to suggest to you the possibility of entirely avoiding this source of misconception in your great work (if not now too late), and also in any future editions of the "Origin," and I think it may be done without difficulty and very effectually by adopting Spencer's term (which he generally uses in preference to Natural Selection)--viz., "survival of the fittest." This term is the plain expression of the fact; Natural Selection is a metaphorical expression of it, and to a certain degree indirect and incorrect, since, even personifying Nature, she does not so much select special variations as exterminate the most unfavourable ones. Combined with the enormous multiplying powers of all organisms, and the "struggle for existence" leading to the constant destruction of by far the largest proportion--facts which no one of your opponents, as far as I am aware, has denied or misunderstood--"the survival of the fittest" rather than of those who were less fit could not possibly be denied or misunderstood. Neither would it be possible to say that to ensure the "survival of the fittest" any intelligent chooser was necessary; whereas when you say Natural Selection acts so as to choose those that are fittest, it IS misunderstood, and apparently always will be. Referring to your book, I find such expressions as "Man selects only for his own good; Nature only for that of the being which she tends." This, it seems, will always be misunderstood; but if you had said "Man selects only for his own good; Nature, by the inevitable 'survival of the fittest,' only for that of the being she tends," it would have been less liable to be so. I find you use the term "Natural Selection" in two senses: (1) for the simple preservation of favourable and rejection of unfavourable variations, in which case it is equivalent to "survival of the fittest"; and (2) for the effect or change produced by this preservation, as when you say, "To sum up the circumstances favourable or unfavourable to Natural Selection," and again, "Isolation, also, is an important element in the process of Natural Selection." Here it is not merely "survival of the fittest," but change produced by survival of the fittest, that is meant. On looking over your fourth chapter, I find that these alterations of terms can be in most cases easily made, while in some cases the addition of "or survival of the fittest" after "Natural Selection" would be best; and in others, less likely to be misunderstood, the original term may stand alone. I could not venture to propose to any other person so great an alteration of terms, but you, I am sure, will give it an impartial consideration, and if you really think the change will produce a better understanding of your work, will not hesitate to adopt it. It is evidently also necessary not to personify "Nature" too much--though I am very apt to do it myself--since people will not understand that all such phrases are metaphors. Natural Selection is, when understood, so necessary and self-evident a principle, that it is a pity it should be in any way obscured; and it therefore seems to me that the free use of "survival of the fittest," which is a compact and accurate definition of it, would tend much to its being more widely accepted, and prevent it being so much misrepresented and misunderstood. There is another objection made by Janet which is also a very common one. It is that the chances are almost infinite against the particular kind of variation required being coincident with each change of external conditions, to enable an animal to become modified by Natural Selection in harmony with such changed conditions; especially when we consider that, to have produced the almost infinite modifications of organic beings, this coincidence must have taken place an almost infinite number of times. Now, it seems to me that you have yourself led to this objection being made, by so often stating the case too strongly against yourself. For example, at the commencement of Chapter IV. you ask if it is "improbable that useful variations should sometimes occur in the course of thousands of generations"; and a little further on you say, "unless profitable variations do occur, Natural Selection can do nothing." Now, such expressions have given your opponents the advantage of assuming that favourable variations are rare accidents, or may even for long periods never occur at all, and thus Janet's argument would appear to many to have great force. I think it would be better to do away with all such qualifying expressions, and constantly maintain (what I certainly believe to be the fact) that variations of every kind are always occurring in every part of every species, and therefore that favourable variations are always ready when wanted. You have, I am sure, abundant materials to prove this; and it is, I believe, the grand fact that renders modification and adaptation to conditions almost always possible. I would put the burthen of proof on my opponents to show that any one organ, structure, or faculty does not vary, even during one generation, among all the individuals of a species; and also to show any mode or way in which any such organ, etc., does not vary. I would ask them to give any reason for supposing that any organ, etc., is ever absolutely identical at any one time in all the individuals of a species, and if not then it is always varying, and there are always materials which, from the simple fact that "the fittest survive," will tend to the modification of the race into harmony with changed conditions. I hope these remarks may be intelligible to you, and that you will be so kind as to let me know what you think of them. I have not heard for some time how you are getting on. I hope you are still improving in health, and that you will now be able to get on with your great work, for which so many thousands are looking with interest. LETTER 191. TO A.R. WALLACE. (191/1. From "Life and Letters," III., page 45.) Down, July 5th [1866]. I have been much interested by your letter, which is as clear as daylight. I fully agree with all that you say on the advantages of H. Spencer's excellent expression of "the survival of the fittest." This, however, had not occurred to me till reading your letter. It is, however, a great objection to this term that it cannot be used as a substantive governing a verb; and that this is a real objection I infer from H. Spencer continually using the words Natural Selection. I formerly thought, probably in an exaggerated degree, that it was a great advantage to bring into connection natural and artificial selection; this indeed led me to use a term in common, and I still think it some advantage. I wish I had received your letter two months ago, for I would have worked in "the survival," etc., often in the new edition of the "Origin," which is now almost printed off, and of which I will of course send you a copy. I will use the term in my next book on domestic animals, etc., from which, by the way, I plainly see that you expect MUCH too much. The term Natural Selection has now been so largely used abroad and at home that I doubt whether it could be given up, and with all its faults I should be sorry to see the attempt made. Whether it will be rejected must now depend "on the survival of the fittest." As in time the term must grow intelligible the objections to its use will grow weaker and weaker. I doubt whether the use of any term would have made the subject intelligible to some minds, clear as it is to others; for do we not see even to the present day Malthus on Population absurdly misunderstood? This reflection about Malthus has often comforted me when I have been vexed at this misstatement of my views. As for M. Janet, he is a metaphysician, and such gentlemen are so acute that I think they often misunderstand common folk. Your criticism on the double sense in which I have used Natural Selection is new to me and unanswerable; but my blunder has done no harm, for I do not believe that any one, excepting you, has ever observed it. Again, I agree that I have said too much about "favourable variations," but I am inclined to think that you put the opposite side too strongly: if every part of every being varied, I do not think we should see the same end or object gained by such wonderfully diversified means. I hope you are enjoying the country, and are in good health, and are working hard at your "Malay Archipelago" book, for I will always put this wish in every note I write to you, as some good people always put in a text. My health keeps much the same, or rather improves, and I am able to work some hours daily. LETTER 192. TO C. LYELL. Down, October 9th [1866]. One line to say that I have received your note and the proofs safely, and will read them with the greatest pleasure; but I am certain I shall not be able to send any criticism on the astronomical chapter (192/1. "Principles of Geology," by Sir Charles Lyell; Edition X., London, 1867. Chapter XIII. deals with "Vicissitudes in Climate how far influenced by Astronomical Causes."), as I am as ignorant as a pig on this head. I shall require some days to read what has been sent. I have just read Chapter IX. (192/2. Chapter IX., "Theory of the Progressive Development of Organic Life at Successive Geological Periods."), and like it extremely; it all seems to me very clear, cautious, and sagacious. You do not allude to one very striking point enough, or at all--viz., the classes having been formerly less differentiated than they now are; and this specialisation of classes must, we may conclude, fit them for different general habits of life as well as the specialisation of particular organs. Page 162 (192/3. On page 163 Lyell refers to the absence of Cetacea in Secondary rocks, and expresses the opinion that their absence "is a negative fact of great significance, which seems more than any other to render it highly improbable that we shall ever find air-breathers of the highest class in any of the Primary strata, or in any of the older members of the Secondary series.") I rather demur to your argument from Cetacea: as they are such greatly modified mammals, they ought to have come in rather later in the series. You will think me rather impudent, but the discussion at the end of Chapter IX. on man (192/4. Loc. cit., pages 167-73, "Introduction of Man, to what extent a Change of the System."), who thinks so much of his fine self, seems to me too long, or rather superfluous, and too orthodox, except for the beneficed clergy. LETTER 193. TO V. CARUS. (193/1. The following letter refers to the 4th edition of the "Origin," 1866, which was translated by Professor Carus, and formed the 3rd German edition. Carus continued to translate Darwin's books, and a strong bond of friendship grew up between author and translator (see "Life and Letters," III., page 48). Nageli's pamphlet was first noticed in the 5th English edition.) Down, November 21st, 1866. ...With respect to a note on Nageli (193/2. "Entstehung und Begriff der Naturhistorischen Art," an Address given before the Royal Academy of Sciences at Munich, March 28th, 1865. See "Life and Letters," III., page 50, for Mr. Darwin's letter to the late Prof. Nageli.) I find on consideration it would be too long; for so good a pamphlet ought to be discussed at full length or not at all. He makes a mistake in supposing that I say that useful characters are always constant. His view about distinct species converging and acquiring the same identical structure is by implication answered in the discussion which I have given on the endless diversity of means for gaining the same end. The most important point, as it seems to me, in the pamphlet is that on the morphological characters of plants, and I find I could not answer this without going into much detail. The answer would be, as it seems to me, that important morphological characters, such as the position of the ovules and the relative position of the stamens to the ovarium (hypogynous, perigynous, etc.) are sometimes variable in the same species, as I incidentally mention when treating of the ray-florets in the Compositae and Umbelliferae; and I do not see how Nageli could maintain that differences in such characters prove an inherent tendency towards perfection. I see that I have forgotten to say that you have my fullest consent to append any discussion which you may think fit to the new edition. As for myself I cannot believe in spontaneous generation, and though I expect that at some future time the principle of life will be rendered intelligible, at present it seems to me beyond the confines of science. LETTER 194. TO T.H. HUXLEY. Down, December 22nd [1866?]. I suppose that you have received Hackel's book (194/1. "Generelle Morphologie," 1866.) some time ago, as I have done. Whenever you have had time to read through some of it, enough to judge by, I shall be very curious to hear your judgment. I have been able to read a page or two here and there, and have been interested and instructed by parts. But my vague impression is that too much space is given to methodical details, and I can find hardly any facts or detailed new views. The number of new words, to a man like myself, weak in his Greek, is something dreadful. He seems to have a passion for defining, I daresay very well, and for coining new words. From my very vague notions on the book, and from its immense size, I should fear a translation was out of the question. I see he often quotes both of us with praise. I am sure I should like the book much, if I could read it straight off instead of groaning and swearing at each sentence. I have not yet had time to read your Physiology (194/2. "Lessons in Elementary Physiology," 1866.) book, except one chapter; but I have just re-read your book on "Man's Place, etc.," and I think I admire it more this second time even than the first. I doubt whether you will ever have time, but if ever you have, do read the chapter on hybridism in the new edition of the "Origin" (194/3. Fourth Edition (1866).), for I am very anxious to make you think less seriously on that difficulty. I have improved the chapter a good deal, I think, and have come to more definite views. Asa Gray and Fritz Muller (the latter especially) think that the new facts on illegitimate offspring of dimorphic plants, throw much indirect light on the subject. Now that I have worked up domestic animals, I am convinced of the truth of the Pallasian (194/4. See Letter 80.) view of loss of sterility under domestication, and this seems to me to explain much. But I had no intention, when I began this note, of running on at such length on hybridism; but you have been Objector-General on this head. LETTER 195. TO T. RIVERS. (195/1. For another letter of Mr. Darwin's to him see "Life and Letters," III., page 57.) Down, December 23rd [1866?]. I do not know whether you will forgive a stranger addressing you. My name may possibly be known to you. I am now writing a book on the variation of animals and plants under domestication; and there is one little piece of information which it is more likely that you could give me than any man in the world, if you can spare half an hour from your professional labours, and are inclined to be so kind. I am collecting all accounts of what some call "sports," that is, of what I shall call "bud-variations," i.e. a moss-rose suddenly appearing on a Provence rose--a nectarine on a peach, etc. Now, what I want to know, and which is not likely to be recorded in print, is whether very slight differences, too slight to be worth propagating, thus appear suddenly by buds. As every one knows, in raising seedlings you may have every gradation from individuals identical with the parent, to slight varieties, to strongly marked varieties. Now, does this occur with buds or do only rather strongly marked varieties thus appear at rare intervals of time by buds? (195/2. Mr. Rivers could not give a decided answer, but he did not remember to have seen slight bud-variations. The question is discussed in "Variation under Domestication," Edition II., Volume I., page 443.) I should be most grateful for information. I may add that if you have observed in your enormous experience any remarkable "bud-variations," and could spare time to inform me, and allow me to quote them on your authority, it would be the greatest favour. I feel sure that these "bud-variations" are most interesting to any one endeavouring to make out what little can be made out on the obscure subject of variation. LETTER 196. TO T. RIVERS. Down, January 7th [1867?]. I thank you much for your letter and the parcel of shoots. The case of the yellow plum is a treasure, and is now safely recorded on your authority in its proper place, in contrast with A. Knight's case of the yellow magnum bonum sporting into red. (196/1. See "Variation under Domestication," Edition II., Volume I., page 399.) I could see no difference in the shoots, except that those of the yellow were thicker, and I presume that this is merely accidental: as you do not mention it, I further presume that there are no further differences in leaves or flowers of the two plums. I am very glad to hear about the yellow ash, and that you yourself have seen the jessamine case. I must confess that I hardly fully believed in it; but now I do, and very surprising it is. In an old French book, published in Amsterdam in 1786 (I think), there is an account, apparently authentic and attested by the writer as an eye-witness, of hyacinth bulbs of two colours being cut in two and grafted, and they sent up single stalks with differently coloured flowers on the two sides, and some flowers parti-coloured. I once thought of offering 5 pounds reward in the "Cottage Gardener" for such a plant; but perhaps it would seem too foolish. No instructions are given when to perform the operation; I have tried two or three times, and utterly failed. I find that I have a grand list of "bud-variations," and to-morrow shall work up such cases as I have about rose-sports, which seem very numerous, and which I see you state to occur comparatively frequently. When a person is very good-natured he gets much pestered--a discovery which I daresay you have made, or anyhow will soon make; for I do want very much to know whether you have sown seed of any moss-roses, and whether the seedlings were moss-roses. (196/2. Moss-roses can be raised from seed ("Variation under Domestication," Edition II., Volume I., page 405.) Has a common rose produced by SEED a moss-rose? If any light comes to you about very slight changes in the buds, pray have the kindness to illuminate me. I have cases of seven or eight varieties of the peach which have produced by "bud-variation" nectarines, and yet only one single case (in France) of a peach producing another closely similar peach (but later in ripening). How strange it is that a great change in the peach should occur not rarely and slighter changes apparently very rarely! How strange that no case seems recorded of new apples or pears or apricots by "bud-variation"! How ignorant we are! But with the many good observers now living our children's children will be less ignorant, and that is a comfort. LETTER 197. TO T.H. HUXLEY. Down, January 7th [1867]. Very many thanks for your letter, which has told me exactly what I wanted to know. I shall give up all thoughts of trying to get the book (197/1. Hackel's "Generelle Morphologie," 1866. See "Life and Letters," III., pages 67, 68.) translated, for I am well convinced that it would be hopeless without too great an outlay. I much regret this, as I should think the work would be useful, and I am sure it would be to me, as I shall never be able to wade through more than here and there a page of the original. To all people I cannot but think that the number of new terms would be a great evil. I must write to him. I suppose you know his address, but in case you do not, it is "to care of Signor Nicolaus Krohn, Madeira." I have sent the MS. of my big book (197/2. "The Variation of Animals and Plants under Domestication," 1868.), and horridly, disgustingly big it will be, to the printers, but I do not suppose it will be published, owing to Murray's idea on seasons, till next November. I am thinking of a chapter on Man, as there has lately been so much said on Natural Selection in relation to man. I have not seen the Duke's (or Dukelet's? how can you speak so of a living real Duke?) book, but must get it from Mudie, as you say he attacks us. (197/3. "The Reign of Law" (1867), by the late Duke of Argyll. See "Life and Letters," III., page 65.) P.S.--Nature never made species mutually sterile by selection, nor will men. LETTER 197. TO E. HACKEL. Down, January 8th [1867]. I received some weeks ago your great work (198/1. "Generelle Morphologie," 1866.); I have read several parts, but I am too poor a German scholar and the book is too large for me to read it all. I cannot tell you how much I regret this, for I am sure that nearly the whole would interest me greatly, and I have already found several parts very useful, such as the discussion on cells and on the different forms of reproduction. I feel sure, after considering the subject deliberately and after consulting with Huxley, that it would be hopeless to endeavour to get a publisher to print an English translation; the work is too profound and too long for our English countrymen. The number of new terms would also, I am sure, tell much against its sale; and, indeed, I wish for my own sake that you had printed a glossary of all the new terms which you use. I fully expect that your book will be highly successful in Germany, and the manner in which you often refer to me in your text, and your dedication and the title, I shall always look at as one of the greatest honours conferred on me during my life. (198/2. As regards the dedication and title this seems a strong expression. The title is "Generelle Morphologie der Organismen. Allgemeine Grundzuge der organischen Formen-Wissenschaft mechanisch begrundet durch die von Charles Darwin reformirte Descendenz-Theorie." The dedication of the second volume is "Den Begrundern der Descendenz-Theorie, den denkenden Naturforschern, Charles Darwin, Wolfgang Goethe, Jean Lamarck widmet diese Grundzuge der Allgemeinen Entwickelungsgeschichte in vorzuglicher Verehrung, der Verfasser.") I sincerely hope that you have had a prosperous expedition, and have met with many new and interesting animals. If you have spare time I should much like to hear what you have been doing and observing. As for myself, I have sent the MS. of my book on domestic animals, etc., to the printers. It turns out to be much too large; it will not be published, I suppose, until next November. I find that we have discussed several of the same subjects, and I think we agree on most points fairly well. I have lately heard several times from Fritz Muller, but he seems now chiefly to be working on plants. I often think of your visit to this house, which I enjoyed extremely, and it will ever be to me a real pleasure to remember our acquaintance. From what I heard in London I think you made many friends there. Shall you return through England? If so, and you can spare the time, we shall all be delighted to see you here again. LETTER 199. TO T. RIVERS. Down, January 11th [1867?]. How rich and valuable a letter you have most kindly sent me! The case of Baronne Prevost (199/1. See "Variation under Domestication," Edition II., Volume I., page 406. Mr. Rivers had a new French rose with a delicate smooth stem, pale glaucous leaves and striped flesh-coloured flowers; on branches thus characterised there appeared "the famous old rose called 'Baronne Prevost,'" with its stout thorny stem and uniform rich-coloured double flowers.), with its different shoots, foliage, spines, and flowers, will be grand to quote. I am extremely glad to hear about the seedling moss-roses. That case of a seedling like a Scotch rose, unless you are sure that no Scotch rose grew near (and it is unlikely that you can remember), must, one would think, have been a cross. I have little compunction for being so troublesome--not more than a grand Inquisitor has in torturing a heretic--for am I not doing a real good public service in screwing crumbs of knowledge out of your wealth of information? P.S. Since the above was written I have read your paper in the "Gardeners' Chronicle": it is admirable, and will, I know, be a treasure to me. I did not at all know how strictly the character of so many flowers is inherited. On my honour, when I began this note I had no thought of troubling you with a question; but you mention one point so interesting, and which I have had occasion to notice, that I must supplicate for a few more facts to quote on your authority. You say that you have one or two seedling peaches (199/2. "On raising Peaches, Nectarines, and other Fruits from Seed." By Thomas Rivers, Sawbridgeworth.--"Gard. Chron." 1866, page 731.) approaching very nearly to thick-fleshed almonds (I know about A. Knight and the Italian hybrid cases). Now, did any almond grow near your mother peach? But especially I want to know whether you remember what shape the stone was, whether flattened like that of an almond; this, botanically, seems the most important distinction. I earnestly wish to quote this. Was the flesh at all sweet? Forgive if you can. Have you kept these seedling peaches? if you would give me next summer a fruit, I want to have it engraved. LETTER 200. TO I. ANDERSON-HENRY. May 22nd [1867]. You are so kind as to offer to lend me Maillet's (200/1. For De Maillet see Mr. Huxley's review on "The Origin of Species" in the "Westminster Review," 1860, reprinted in "Lay Sermons," 1870, page 314. De Maillet's evolutionary views were published after his death in 1748 under the name of Telliamed (De Maillet spelt backwards).) work, which I have often heard of, but never seen. I should like to have a look at it, and would return it to you in a short time. I am bound to read it, as my former friend and present bitter enemy Owen generally ranks me and Maillet as a pair of equal fools. LETTER 201. TO J.D. HOOKER. Down, April 4th [1867]. You have done me a very great service in sending me the pages of the "Farmer." I do not know whether you wish it returned; but I will keep it unless I hear that you want it. Old I. Anderson-Henry passes a magnificent but rather absurd eulogium on me; but the point of such extreme value in my eyes is Mr. Traill's (201/1. Mr. Traill's results are given at page 420 of "Animals and Plants," Edition II., Volume I. In the "Life and Letters of G.J. Romanes," 1896, an interesting correspondence is published with Mr. Darwin on this subject. The plan of the experiments suggested to Romanes was to raise seedlings from graft-hybrids: if the seminal offspring of plants hybridised by grafting should show the hybrid character, it would be striking evidence in favour of pangenesis. The experiment, however, did not succeed.) statement that he made a mottled mongrel by cutting eyes through and joining two kinds of potatoes. (201/2. For an account of similar experiments now in progress, see a "Note on some Grafting Experiments" by R. Biffen in the "Annals of Botany," Volume XVI., page 174, 1902.) I have written to him for full information, and then I will set to work on a similar trial. It would prove, I think, to demonstration that propagation by buds and by the sexual elements are essentially the same process, as pangenesis in the most solemn manner declares to be the case. LETTER 202. TO T.H. HUXLEY. Down, June 12th [1867?]. We come up on Saturday, the 15th, for a week. I want much to see you for a short time to talk about my youngest boy and the School of Mines. I know it is rather unreasonable, but you must let me come a little after 10 o'clock on Sunday morning, the 16th. If in any way inconvenient, send me a line to "6, Queen Anne Street W.,"; but if I do not hear, I will (stomacho volente) call, but I will not stay very long and spoil your whole morning as a holiday. Will you turn two or three times in your mind this question: what I called "pangenesis" means that each cell throws off an atom of its contents or a gemmule, and that these aggregated form the true ovule or bud, etc.? Now I want to know whether I could not invent a better word. "Cyttarogenesis" (202/1. From kuttaros, a bee's-cell: cytogenesis would be a natural form of the word from kutos.)--i.e. cell-genesis--is more true and expressive, but long. "Atomogenesis" sounds rather better, I think, but an "atom" is an object which cannot be divided; and the term might refer to the origin of atoms of inorganic matter. I believe I like "pangenesis" best, though so indefinite; and though my wife says it sounds wicked, like pantheism; but I am so familiar now with this word, that I cannot judge. I supplicate you to help me. LETTER 203. TO A.R. WALLACE. Down, October, 12th and 13th [1867]. I ordered the journal (203/1. "Quarterly Journal of Science," October, 1867, page 472. A review of the Duke of Argyll's "Reign of Law.") a long time ago, but by some oversight received it only yesterday, and read it. You will think my praise not worth having, from being so indiscriminate; but if I am to speak the truth, I must say I admire every word. You have just touched on the points which I particularly wished to see noticed. I am glad you had the courage to take up Angraecum (203/2. Angraecum sesquipedale, a Madagascan orchid, with a whiplike nectary, 11 to 12 inches in length, which, according to Darwin ("Fertilisation of Orchids," Edition II., page 163), is adapted to the visits of a moth with a proboscis of corresponding length. He points out that there is no difficulty in believing in the existence of such a moth as F. Muller has described ("Nature," 1873, page 223)--a Brazilian sphinx-moth with a trunk of 10 to 11 inches in length. Moreover, Forbes has given evidence to show that such an insect does exist in Madagascar ("Nature," VIII., 1873, page 121). The case of Angraecum was put forward by the Duke of Argyll as being necessarily due to the personal contrivance of the Deity. Mr. Wallace (page 476) shows that both proboscis and nectary might be increased in length by means of Natural Selection. It may be added that Hermann Muller has shown good grounds for believing that mutual specialisation of this kind is beneficial both to insect and plant.) after the Duke's attack; for I believe the principle in this case may be widely applied. I like the figure, but I wish the artist had drawn a better sphinx. With respect to beauty, your remarks on hideous objects and on flowers not being made beautiful except when of practical use to them, strike me as very good. On this one point of beauty I can hardly think that the Duke was quite candid. I have used in the concluding paragraph of my present book precisely the same argument as you have, even bringing in the bull-dog (203/3. "Variation of Animals and Plants," Edition I., Volume II., page 431: "Did He cause the frame and mental qualities of the dog to vary in order that a breed might be formed of indomitable ferocity, with jaws fitted to pin down the bull for man's brutal sport?"), with respect to variations not having been specially ordained. Your metaphor of the river (203/4. See Wallace, op. cit., pages 477-8. He imagines an observer examining a great river-system, and finding everywhere adaptations which reveal the design of the Creator. "He would see special adaptation to the wants of man in broad, quiet, navigable rivers, through fertile alluvial plains that would support a large population, while the rocky streams and mountain torrents were confined to those sterile regions suitable only for a small population of shepherds and herdsmen.') is new to me, and admirable; but your other metaphor, in which you compare classification and complex machines, does not seem to me quite appropriate, though I cannot point out what seems deficient. The point which seems to me strong is that all naturalists admit that there is a natural classification, and it is this which descent explains. I wish you had insisted a little more against the "North British" (203/5. At page 485 Mr. Wallace deals with Fleeming Jenkin's review in the "North British Review," 1867. The review strives to show that there are strict limits to variation, since the most rigorous and long-continued selection does not indefinitely increase such a quality as the fleetness of a racehorse. On this Mr. Wallace remarks that "this argument fails to meet the real question," which is, not whether indefinite change is possible, "but whether such differences as do occur in nature could have been produced by the accumulation of variations by selection.") on the reviewer assuming that each variation which appears is a strongly marked one; though by implication you have made this very plain. Nothing in your whole article has struck me more than your view with respect to the limit of fleetness in the racehorse and other such cases: I shall try and quote you on this head in the proof of my concluding chapter. I quite missed this explanation, though in the case of wheat I hit upon something analogous. I am glad you praise the Duke's book, for I was much struck with it. The part about flight seemed to me at first very good; but as the wing is articulated by a ball-and-socket joint, I suspect the Duke would find it very difficult to give any reason against the belief that the wing strikes the air more or less obliquely. I have been very glad to see your article and the drawing of the butterfly in "Science Gossip." By the way, I cannot but think that you push protection too far in some cases, as with the stripes on the tiger. I have also this morning read an excellent abstract in the "Gardeners' Chronicle" of your paper on nests. (203/6. An abstract of a paper on "Birds' Nests and Plumage," read before the British Association: see "Gard. Chron." 1867, page 1047.) I was not by any means fully converted by your letter, but I think now I am so; and I hope it will be published somewhere in extenso. It strikes me as a capital generalisation, and appears to me even more original than it did at first... I have finished Volume I. of my book ["Variation of Animals and Plants"], and I hope the whole will be out by the end of November. If you have the patience to read it through, which is very doubtful, you will find, I think, a large accumulation of facts which will be of service to you in future papers; and they could not be put to better use, for you certainly are a master in the noble art of reasoning. LETTER 204. TO T.H. HUXLEY. Down, October 3rd [no date]. I know you have no time for speculative correspondence; and I did not in the least expect an answer to my last. But I am very glad to have had it, for in my eclectic work the opinions of the few good men are of great value to me. I knew, of course, of the Cuvierian view of classification (204/1. Cuvier proved that "animals cannot be arranged in a single series, but that there are several distinct plans of organisation to be observed among them, no one of which, in its highest and most complicated modification, leads to any of the others" (Huxley's "Darwiniana," page 215).); but I think that most naturalists look for something further, and search for "the natural system,"--"for the plan on which the Creator has worked," etc., etc. It is this further element which I believe to be simply genealogical. But I should be very glad to have your answer (either when we meet or by note) to the following case, taken by itself, and not allowing yourself to look any further than to the point in question. Grant all races of man descended from one race--grant that all the structure of each race of man were perfectly known--grant that a perfect table of the descent of each race was perfectly known--grant all this, and then do you not think that most would prefer as the best classification, a genealogical one, even if it did occasionally put one race not quite so near to another, as it would have stood, if collocated by structure alone? Generally, we may safely presume, that the resemblance of races and their pedigrees would go together. I should like to hear what you would say on this purely theoretical case. It might be asked why is development so all-potent in classification, as I fully admit it is? I believe it is because it depends on, and best betrays, genealogical descent; but this is too large a point to enter on. LETTER 205. TO C. LYELL. Down, December 7th [1867]. I send by this post the article in the Victorian Institute with respect to frogs' spawn. If you remember in your boyhood having ever tried to take a small portion out of the water, you will remember that it is most difficult. I believe all the birds in the world might alight every day on the spawn of batrachians, and never transport a single ovum. With respect to the young of molluscs, undoubtedly if the bird to which they were attached alighted on the sea, they would be instantly killed; but a land-bird would, I should think, never alight except under dire necessity from fatigue. This, however, has been observed near Heligoland (205/1. Instances are recorded by Gatke in his "Heligoland as an Ornithological Observatory" (translated by Rudolph Rosenstock, Edinburgh, 1895) of land-birds, such as thrushes, buntings, finches, etc., resting for a short time on the surface of the water. The author describes observations made by himself about two miles west of Heligoland (page 129).); and land-birds, after resting for a time on the tranquil sea, have been seen to rise and continue their flight. I cannot give you the reference about Heligoland without much searching. This alighting on the sea may aid you in your unexpected difficulty of the too-easy diffusion of land-molluscs by the agency of birds. I much enjoyed my morning's talk with you. LETTER 206. TO F. HILDEBRAND. Down, January 5th [1868]. I thank you for your letter, which has quite delighted me. I sincerely congratulate you on your success in making a graft-hybrid (206/1. Prof. Hildebrand's paper is in the "Bot. Zeitung," 1868: the substance is given in "Variation of Animals and Plants," Edition II., Volume I., page 420.), for I believe it to be a most important observation. I trust that you will publish full details on this subject and on the direct action of pollen (206/2. See Prof. Hildebrand, "Bot. Zeitung," 1868, and "Variation of Animals and Plants," Edition II., Volume I., page 430. A yellow-grained maize was fertilised with pollen from a brown-grained one; the result was that ears were produced bearing both yellow and dark-coloured grains.): I hope that you will be so kind as to send me a copy of your paper. If I had succeeded in making a graft-hybrid of the potato, I had intended to raise seedlings from the graft-hybrid and from the two parent-forms (excluding insects) and carefully compare the offspring. This, however, would be difficult on account of the sterility and variability of the potato. When in the course of a few months you receive my second volume (206/3. This sentence may be paraphrased--"When you receive my book and read the second volume."), you will see why I think these two subjects so important. They have led me to form a hypothesis on the various forms of reproduction, development, inheritance, etc., which hypothesis, I believe, will ultimately be accepted, though how it will be now received I am very doubtful. Once again I congratulate you on your success. LETTER 207. TO J.D. HOOKER. Down, January 6th [1868]. Many thanks about names of plants, synonyms, and male flowers--all that I wanted. I have been glad to see Watson's letter, and am sorry he is a renegade about Natural Selection. It is, as you say, characteristic, with the final fling at you. His difficulty about the difference between the two genera of St. Helena Umbellifers is exactly the same as what Nageli has urged in an able pamphlet (207/1. "Ueber Entstehung und Begriff der naturhist. Art." "Sitz. der K. Bayer. Akad. Der Wiss. zu Munchen," 1865. Some of Nageli's points are discussed in the "Origin," Edition V., page 151.), and who in consequence maintains that there is some unknown innate tendency to progression in all organisms. I said in a letter to him that of course I could not in the least explain such cases; but that they did not seem to me of overwhelming force, as long as we are quite ignorant of the meaning of such structures, whether they are of any service to the plants, or inevitable consequences of modifications in other parts. I cannot understand what Watson means by the "counter-balance in nature" to divergent variation. There is the counterbalance of crossing, of which my present work daily leads me to see more and more the efficiency; but I suppose he means something very different. Further, I believe variation to be divergent solely because diversified forms can best subsist. But you will think me a bore. I enclose half a letter from F. Muller (which please return) for the chance of your liking to see it; though I have doubted much about sending it, as you are so overworked. I imagine the Solanum-like flower is curious. I heard yesterday to my joy that Dr. Hildebrand has been experimenting on the direct action of pollen on the mother-plant with success. He has also succeeded in making a true graft-hybrid between two varieties of potatoes, in which I failed. I look at this as splendid for pangenesis, as being strong evidence that bud-reproduction and seminal reproduction do not essentially differ. My book is horribly delayed, owing to the accursed index-maker. (207/2. Darwin thoroughly appreciated the good work put into the index of "The Variation of Animals and Plants.") I have almost forgotten it! LETTER 208. TO T.H. HUXLEY. Down, January 30th [1868]. Most sincere thanks for your kind congratulations. I never received a note from you in my life without pleasure; but whether this will be so after you have read pangenesis (208/1. In Volume II. of "Animals and Plants, 1868.), I am very doubtful. Oh Lord, what a blowing up I may receive! I write now partly to say that you must not think of looking at my book till the summer, when I hope you will read pangenesis, for I care for your opinion on such a subject more than for that of any other man in Europe. You are so terribly sharp-sighted and so confoundedly honest! But to the day of my death I will always maintain that you have been too sharp-sighted on hybridism; and the chapter on the subject in my book I should like you to read: not that, as I fear, it will produce any good effect, and be hanged to you. I rejoice that your children are all pretty well. Give Mrs. Huxley the enclosed (208/2. Queries on Expression.), and ask her to look out when one of her children is struggling and just going to burst out crying. A dear young lady near here plagued a very young child for my sake, till it cried, and saw the eyebrows for a second or two beautifully oblique, just before the torrent of tears began. The sympathy of all our friends about George's success (it is the young Herald) (208/3. His son George was Second Wrangler in 1868; as a boy he was an enthusiast in heraldry.) has been a wonderful pleasure to us. George has not slaved himself, which makes his success the more satisfactory. Farewell, my dear Huxley, and do not kill yourself with work. (209/1. The following group of letters deals with the problem of the causes of the sterility of hybrids. Mr. Darwin's final view is given in the "Origin," sixth edition (page 384, edition 1900). He acknowledges that it would be advantageous to two incipient species, if by physiological isolation due to mutual sterility, they could be kept from blending: but he continues, "After mature reflection it seems to me that this could not have been effected through Natural Selection." And finally he concludes (page 386):-- "But it would be superfluous to discuss this question in detail; for with plants we have conclusive evidence that the sterility of crossed species must be due to some principle quite independent of Natural Selection. Both Gartner and Kolreuter have proved that in genera including numerous species, a series can be formed from species which when crossed yield fewer and fewer seeds, to species which never produce a single seed, but yet are affected by the pollen of certain other species, for the germen swells. It is here manifestly impossible to select the more sterile individuals, which have already ceased to yield seeds; so that this acme of sterility, when the germen alone is affected, cannot have been gained through selection; and from the laws governing the various grades of sterility being so uniform throughout the animal and vegetable kingdoms, we may infer that the cause, whatever it may be, is the same or nearly the same in all cases." Mr. Wallace, on the other hand, still adheres to his view: see his "Darwinism," 1889, page 174, and for a more recent statement see page 292, note 1, Letter 211, and page 299. The discussion of 1868 began with a letter from Mr. Wallace, written towards the end of February, giving his opinion on the "Variation of Animals and Plants;" the discussion on the sterility of hybrids is at page 185, Volume II., of the first edition.) LETTER 209. A.R. WALLACE TO CHARLES DARWIN. February 1868. The only parts I have yet met with where I somewhat differ from your views, are in the chapter on the causes of variability, in which I think several of your arguments are unsound: but this is too long a subject to go into now. Also, I do not see your objection to sterility between allied species having been aided by Natural Selection. It appears to me that, given a differentiation of a species into two forms, each of which was adapted to a special sphere of existence, every slight degree of sterility would be a positive advantage, not to the individuals who were sterile, but to each form. If you work it out, and suppose the two incipient species a...b to be divided into two groups, one of which contains those which are fertile when the two are crossed, the other being slightly sterile, you will find that the latter will certainly supplant the former in the struggle for existence; remembering that you have shown that in such a cross the offspring would be more vigorous than the pure breed, and therefore would certainly soon supplant them, and as these would not be so well adapted to any special sphere of existence as the pure species a and b, they would certainly in their turn give way to a and b. LETTER 210. TO A.R. WALLACE. February 27th [1868]. I shall be very glad to hear, at some future day, your criticisms on the "causes of variability." Indeed, I feel sure that I am right about sterility and Natural Selection. Two of my grown-up children who are acute reasoners have two or three times at intervals tried to prove me wrong; and when your letter came they had another try, but ended by coming back to my side. I do not quite understand your case, and we think that a word or two is misplaced. I wish some time you would consider the case under the following point of view. If sterility is caused or accumulated through Natural Selection, then, as every degree exists up to absolute barrenness, Natural Selection must have the power of increasing it. Now take two species A and B, and assume that they are (by any means) half-sterile, i.e., produce half the full number of offspring. Now try and make (by Natural Selection) A and B absolutely sterile when crossed, and you will find how difficult it is. I grant, indeed it is certain, that the degree of the sterility of the individuals of A and B will vary; but any such extra-sterile individuals of, we will say A, if they should hereafter breed with other individuals of A, will bequeath no advantage to their progeny, by which these families will tend to increase in number over other families of A, which are not more sterile when crossed with B. But I do not know that I have made this any clearer than in the chapter in my book. It is a most difficult bit of reasoning, which I have gone over and over again on paper with diagrams. (210/1. This letter appeared in "Life and Letters," III., page 80.) LETTER 211. A.R. WALLACE TO CHARLES DARWIN. March 1st, 1868. I beg to enclose what appears to me a demonstration on your own principles, that Natural Selection could produce sterility of hybrids. If it does not convince you, I shall be glad if you will point out where the fallacy lies. I have taken the two cases of a slight sterility overcoming perfect fertility, and of a perfect sterility overcoming a partial fertility,--the beginning and end of the process. You admit that variations in fertility and sterility occur, and I think you will also admit that if I demonstrate that a considerable amount of sterility would be advantageous to a variety, that is sufficient proof that the slightest variation in that direction would be useful also, and would go on accumulating. 1. Let there be a species which has varied into two forms, each adapted to existing conditions (211/1. "Existing conditions," means of course new conditions which have now come into existence. And the "two" being both better adapted than the parent form, means that they are better adapted each to a special environment in the same area--as one to damp, another to dry places; one to woods, another to open grounds, etc., etc., as Darwin had already explained. A.R.W. (1899).) better than the parent form, which they supplant. 2. If these two forms, which are supposed to co-exist in the same district, do not intercross, Natural Selection will accumulate favourable variations, till they become sufficiently well adapted to their conditions of life and form two allied species. 3. But if these two forms freely intercross with each other and produce hybrids which are also quite fertile inter se, then the formation of the two distinct races or species will be retarded or perhaps entirely prevented; for the offspring of the crossed unions will be more vigorous owing to the cross, although less adapted to their conditions of life than either of the pure breeds. (211/2. After "pure breeds," add "because less specialised." A.R.W. (1899).) 4. Now let a partial sterility of some individuals of these two forms arise when they intercross; and as this would probably be due to some special conditions of life, we may fairly suppose it to arise in some definite portion of the area occupied by the two forms. 5. The result is that in this area hybrids will not increase so rapidly as before; and as by the terms of the problem the two pure forms are better suited to the conditions of life than the hybrids, they will tend to supplant the latter altogether whenever the struggle for existence becomes severe. 6. We may fairly suppose, also, that as soon as any sterility appears under natural conditions, it will be accompanied by some disinclination to cross-unions; and this will further diminish the production of hybrids. 7. In the other part of the area, however, where hybridism occurs unchecked, hybrids of various degrees will soon far outnumber the parent or pure form. 8. The first result, then, of a partial sterility of crosses appearing in one part of the area occupied by the two forms, will be, that the GREAT MAJORITY of the individuals will there consist of the pure forms only, while in the rest of the area these will be in a minority,--which is the same as saying, that the new sterile or physiological variety of the two forms will be better suited to the conditions of existence than the remaining portion which has not varied physiologically. 9. But when the struggle for existence becomes severe, that variety which is best adapted to the conditions of existence always supplants that which is imperfectly adapted; therefore by Natural Selection the sterile varieties of the two forms will become established as the only ones. 10. Now let a fresh series of variations in the amount of sterility and in the disinclination to crossed unions occur,--also in certain parts of the area: exactly the same result must recur, and the progeny of this new physiological variety again in time occupy the whole area. 11. There is yet another consideration that supports this view. It seems probable that the variations in amount of sterility would to some extent concur with and perhaps depend upon the structural variations; so that just in proportion as the two forms diverged and became better adapted to the conditions of existence, their sterility would increase. If this were the case, then Natural Selection would act with double strength, and those varieties which were better adapted to survive both structurally and physiologically, would certainly do so. (211/3. The preceding eleven paragraphs are substantially but not verbally identical with the statement of the argument in Mr. Wallace's "Darwinism," 1889. Pages 179, 180, note 1.) 12. Let us now consider the more difficult case of two allied species A, B, in the same area, half the individuals of each (As, Bs) being absolutely sterile, the other half (Af, Bf) being partially fertile: will As, Bs ultimately exterminate Af, Bf? 13. To avoid complication, it must be granted, that between As and Bs no cross-unions take place, while between Af and Bf cross-unions are as frequent as direct unions, though much less fertile. We must also leave out of consideration crosses between As and Af, Bs and Bf, with their various approaches to sterility, as I believe they will not affect the final result, although they will greatly complicate the problem. 14. In the first generation there will result: 1st, The pure progeny of As and Bs; 2nd, The pure progeny of Af and of Bf; and 3rd, The hybrid progeny of Af, Bf. 15. Supposing that, in ordinary years, the increased constitutional vigour of the hybrids exactly counterbalances their imperfect adaptations to conditions, there will be in the second generation, besides these three classes, hybrids of the second degree between the first hybrids and Af and Bf respectively. In succeeding generations there will be hybrids of all degrees, varying between the first hybrids and the almost pure types of Af and Bf. 16. Now, if at first the number of individuals of As, Bs, Af and Bf were equal, and year after year the total number continues stationary, I think it can be proved that, while half will be the pure progeny of As and Bs, the other half will become more and more hybridised, until the whole will be hybrids of various degrees. 17. Now, this hybrid and somewhat intermediate race cannot be so well adapted to the conditions of life as the two pure species, which have been formed by the minute adaptation to conditions through Natural Selection; therefore, in a severe struggle for existence, the hybrids must succumb, especially as, by hypothesis, their fertility would not be so great as that of the two pure species. 18. If we were to take into consideration the unions of As with Af and Bs with Bf, the results would become very complicated, but it must still lead to there being a number of pure forms entirely derived from As and Bs, and of hybrid forms mainly derived from Af and Bf; and the result of the struggle of these two sets of individuals cannot be doubtful. 19. If these arguments are sound, it follows that sterility may be accumulated and increased, and finally made complete by Natural Selection, whether the sterile varieties originate together in a definite portion of the area occupied by the two species, or occur scattered over the whole area. (211/4. The first part of this discussion should be considered alone, as it is both more simple and more important. I now believe that the utility, and therefore the cause of sterility between species, is during the process of differentiation. When species are fully formed, the occasional occurrence of hybrids is of comparatively small importance, and can never be a danger to the existence of the species. A.R.W. (1899).) P.S.--In answer to the objection as to the unequal sterility of reciprocal crosses ("Variation, etc." Volume II., page 186) I reply that, as far as it went, the sterility of one cross would be advantageous even if the other cross was fertile: and just as characters now co-ordinated may have been separately accumulated by Natural Selection, so the reciprocal crosses may have become sterile one at a time. LETTER 212. TO A.R. WALLACE. 4, Chester Place, March 17th, 1868. (212/1. Mr. Darwin had already written a short note to Mr. Wallace expressing a general dissent from his view.) I do not feel that I shall grapple with the sterility argument till my return home; I have tried once or twice, and it has made my stomach feel as if it had been placed in a vice. Your paper has driven three of my children half mad--one sat up till 12 o'clock over it. My second son, the mathematician, thinks that you have omitted one almost inevitable deduction which apparently would modify the result. He has written out what he thinks, but I have not tried fully to understand him. I suppose that you do not care enough about the subject to like to see what he has written. LETTER 212A. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, March, 24th [1868]. I return your son's notes with my notes on them. Without going into any details, is not this a strong general argument? 1. A species varies occasionally in two directions, but owing to their free intercrossing the varieties never increase. 2. A change of conditions occurs which threatens the existence of the species; but the two varieties are adapted to the changing conditions, and if accumulated will form two new species adapted to the new conditions. 3. Free crossing, however, renders this impossible, and so the species is in danger of extinction. 4. If sterility would be induced, then the pure races would increase more rapidly, and replace the old species. 5. It is admitted that partial sterility between varieties does occasionally occur. It is admitted [that] the degree of this sterility varies; is it not probable that Natural Selection can accumulate these variations, and thus save the species? If Natural Selection can NOT do this, how do species ever arise, except when a variety is isolated? Closely allied species in distinct countries being sterile is no difficulty; for either they diverged from a common ancestor in contact, and Natural Selection increased the sterility, or they were isolated, and have varied since: in which case they have been for ages influenced by distinct conditions which may well produce sterility. If the difficulty of grafting was as great as the difficulty of crossing, and as regular, I admit it would be a most serious objection. But it is not. I believe many distinct species can be grafted, while others less distinct cannot. The regularity with which natural species are sterile together, even when very much alike, I think is an argument in favour of the sterility having been generally produced by Natural Selection for the good of the species. The other difficulty, of unequal sterility of reciprocal crosses, seems none to me; for it is a step to more complete sterility, and as such would be increased by selection. LETTER 213. TO A.R. WALLACE. Down, April 6th [1868]. I have been considering the terrible problem. Let me first say that no man could have more earnestly wished for the success of Natural Selection in regard to sterility than I did; and when I considered a general statement (as in your last note) I always felt sure it could be worked out, but always failed in detail. The cause being, as I believe, that Natural Selection cannot effect what is not good for the individual, including in this term a social community. It would take a volume to discuss all the points, and nothing is so humiliating to me as to agree with a man like you (or Hooker) on the premises and disagree about the result. I agree with my son's argument and not with the rejoinder. The cause of our difference, I think, is that I look at the number of offspring as an important element (all circumstances remaining the same) in keeping up the average number of individuals within any area. I do not believe that the amount of food by any means is the sole determining cause of number. Lessened fertility is equivalent to a new source of destruction. I believe if in one district a species produced from any cause fewer young, the deficiency would be supplied from surrounding districts. This applies to your Paragraph 5. (213/1. See Letter 211.) If the species produced fewer young from any cause in every district, it would become extinct unless its fertility were augmented through Natural Selection (see H. Spencer). I demur to probability and almost to possibility of Paragraph 1., as you start with two forms within the same area, which are not mutually sterile, and which yet have supplanted the parent-form. (Paragraph 6.) I know of no ghost of a fact supporting belief that disinclination to cross accompanies sterility. It cannot hold with plants, or the lower fixed aquatic animals. I saw clearly what an immense aid this would be, but gave it up. Disinclination to cross seems to have been independently acquired, probably by Natural Selection; and I do not see why it would not have sufficed to have prevented incipient species from blending to have simply increased sexual disinclination to cross. (Paragraph 11.) I demur to a certain extent to amount of sterility and structural dissimilarity necessarily going together, except indirectly and by no means strictly. Look at vars. of pigeons, fowls, and cabbages. I overlooked the advantage of the half-sterility of reciprocal crosses; yet, perhaps from novelty, I do not feel inclined to admit probability of Natural Selection having done its work so queerly. I will not discuss the second case of utter sterility, but your assumptions in Paragraph 13 seem to me much too complicated. I cannot believe so universal an attribute as utter sterility between remote species was acquired in so complex a manner. I do not agree with your rejoinder on grafting: I fully admit that it is not so closely restricted as crossing, but this does not seem to me to weaken the case as one of analogy. The incapacity of grafting is likewise an invariable attribute of plants sufficiently remote from each other, and sometimes of plants pretty closely allied. The difficulty of increasing the sterility through Natural Selection of two already sterile species seems to me best brought home by considering an actual case. The cowslip and primrose are moderately sterile, yet occasionally produce hybrids. Now these hybrids, two or three or a dozen in a whole parish, occupy ground which might have been occupied by either pure species, and no doubt the latter suffer to this small extent. But can you conceive that any individual plants of the primrose and cowslip which happened to be mutually rather more sterile (i.e. which, when crossed, yielded a few less seed) than usual, would profit to such a degree as to increase in number to the ultimate exclusion of the present primrose and cowslip? I cannot. My son, I am sorry to say, cannot see the full force of your rejoinder in regard to second head of continually augmented sterility. You speak in this rejoinder, and in Paragraph 5, of all the individuals becoming in some slight degree sterile in certain districts: if you were to admit that by continued exposure to these same conditions the sterility would inevitably increase, there would be no need of Natural Selection. But I suspect that the sterility is not caused so much by any particular conditions as by long habituation to conditions of any kind. To speak according to pangenesis, the gemmules of hybrids are not injured, for hybrids propagate freely by buds; but their reproductive organs are somehow affected, so that they cannot accumulate the proper gemmules, in nearly the same manner as the reproductive organs of a pure species become affected when exposed to unnatural conditions. This is a very ill-expressed and ill-written letter. Do not answer it, unless the spirit urges you. Life is too short for so long a discussion. We shall, I greatly fear, never agree. LETTER 214. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, [April?] 8th, 1868. I am sorry you should have given yourself the trouble to answer my ideas on sterility. If you are not convinced, I have little doubt but that I am wrong; and, in fact, I was only half convinced by my own arguments, and I now think there is about an even chance that Natural Selection may or may not be able to accumulate sterility. If my first proposition is modified to the existence of a species and a variety in the same area, it will do just as well for my argument. Such certainly do exist. They are fertile together, and yet each maintains itself tolerably distinct. How can this be, if there is no disinclination to crossing? My belief certainly is that number of offspring is not so important an element in keeping up population of a species as supply of food and other favourable conditions; because the numbers of a species constantly vary greatly in different parts of its own area, whereas the average number of offspring is not a very variable element. However, I will say no more, but leave the problem as insoluble, only fearing that it will become a formidable weapon in the hands of the enemies of Natural Selection. LETTER 215. TO J.D. HOOKER. (215/1. The following extract from a letter to Sir Joseph Hooker (dated April 3rd, 1868) refers to his Presidential Address for the approaching meeting of the British Association at Norwich. Some account of Sir Joseph's success is given in the "Life and Letters," III., page 100, also in Huxley's "Life," Volume I., page 297, where Huxley writes to Darwin:-- "We had a capital meeting at Norwich, and dear old Hooker came out in great force, as he always does in emergencies. The only fault was the terrible 'Darwinismus' which spread over the section and crept out when you least expected it, even in Fergusson's lecture on 'Buddhist Temples.' You will have the rare happiness to see your ideas triumphant during your lifetime. "P.S.--I am going into opposition; I can't stand it.") Down, April 3rd [1868]. I have been thinking over your Presidential Address; I declare I made myself quite uncomfortable by fancying I had to do it, and feeling myself utterly dumbfounded. But I do not believe that you will find it so difficult. When you come to Down I shall be very curious to hear what your ideas are on the subject. Could you make anything out of a history of the great steps in the progress of Botany, as representing the whole of Natural History? Heaven protect you! I suppose there are men to whom such a job would not be so awful as it appears to me...If you had time, you ought to read an article by W. Bagehot in the April number of the "Fortnightly" (215/2. "Physic and Politics," "Fortnightly Review," Volume III., page 452, 1868.), applying Natural Selection to early or prehistoric politics, and, indeed, to late politics,--this you know is your view. LETTER 216. A.R. WALLACE TO CHARLES DARWIN. 9, St. Mark's Crescent, N.W., August 16th [1868]. I ought to have written before to thank you for the copies of your papers on Primula and on "Cross-unions of Dimorphic Plants, etc." The latter is particularly interesting and the conclusion most important; but I think it makes the difficulty of how these forms, with their varying degrees of sterility, originated, greater than ever. If "natural selection" could not accumulate varying degrees of sterility for the plant's benefit, then how did sterility ever come to be associated with one cross of a trimorphic plant rather than another? The difficulty seems to be increased by the consideration that the advantage of a cross with a distinct individual is gained just as well by illegitimate as by legitimate unions. By what means, then, did illegitimate unions ever become sterile? It would seem a far simpler way for each plant's pollen to have acquired a prepotency on another individual's stigma over that of the same individual, without the extraordinary complication of three differences of structure and eighteen different unions with varying degrees of sterility! However, the fact remains an excellent answer to the statement that sterility of hybrids proves the absolute distinctness of the parents. I have been reading with great pleasure Mr. Bentham's last admirable address (216/1. "Proc. Linn. Soc." 1867-8, page lvii.), in which he so well replies to the gross misstatements of the "Athenaeum;" and also says award in favour of pangenesis. I think we may now congratulate you on having made a valuable convert, whose opinions on the subject, coming so late and being evidently so well considered, will have much weight. I am going to Norwich on Tuesday to hear Dr. Hooker, who I hope will boldly promulgate "Darwinism" in his address. (216/2. Sir Joseph Hooker's Presidential Address at the British Association Meeting.) Shall we have the pleasure of seeing you there? I am engaged in negociations about my book. Hoping you are well and getting on with your next volumes. (216/3. We are permitted by Mr. Wallace to append the following note as to his more recent views on the question of Natural Selection and sterility:-- "When writing my "Darwinism," and coming again to the consideration of this problem of the effect of Natural Selection in accumulating variations in the amount of sterility between varieties or incipient species twenty years later, I became more convinced, than I was when discussing with Darwin, of the substantial accuracy of my argument. Recently a correspondent who is both a naturalist and a mathematician has pointed out to me a slight error in my calculation at page 183 (which does not, however, materially affect the result), disproving the 'physiological selection' of the late Dr. Romanes, but he can see no fallacy in my argument as to the power of Natural Selection to increase sterility between incipient species, nor, so far as I am aware, has any one shown such fallacy to exist. "On the other points on which I differed from Mr. Darwin in the foregoing discussion--the effect of high fertility on population of a species, etc.--I still hold the views I then expressed, but it would be out of place to attempt to justify them here." A.R.W. (1899).) LETTER 217. TO C. LYELL. Down, October 4th [1867]. With respect to the points in your note, I may sometimes have expressed myself with ambiguity. At the end of Chapter XXIII., where I say that marked races are not often (you omit "often") produced by changed conditions (217/1. "Hence, although it must be admitted that new conditions of life do sometimes definitely affect organic beings, it may be doubted whether well-marked races have often been produced by the direct action of changed conditions without the aid of selection either by man or nature." ("Animals and Plants," Volume II., page 292, 1868.)), I intended to refer to the direct action of such conditions in causing variation, and not as leading to the preservation or destruction of certain forms. There is as wide a difference in these two respects as between voluntary selection by man and the causes which induce variability. I have somewhere in my book referred to the close connection between Natural Selection and the action of external conditions in the sense which you specify in your note. And in this sense all Natural Selection may be said to depend on changed conditions. In the "Origin" I think I have underrated (and from the cause which you mention) the effects of the direct action of external conditions in producing varieties; but I hope in Chapter XXIII. I have struck as fair a balance as our knowledge permits. It is wonderful to me that you have patience to read my slips, and I cannot but regret, as they are so imperfect; they must, I think, give you a wrong impression, and had I sternly refused, you would perhaps have thought better of my book. Every single slip is greatly altered, and I hope improved. With respect to the human ovule, I cannot find dimensions given, though I have often seen the statement. My impression is that it would be just or barely visible if placed on a clear piece of glass. Huxley could answer your question at once. I have not been well of late, and have made slow progress, but I think my book will be finished by the middle of November. LETTER 218. A.R. WALLACE TO CHARLES DARWIN. [End of February, 1868] I am in the second volume of your book, and I have been astonished at the immense number of interesting facts you have brought together. I read the chapter on pangenesis first, for I could not wait. I can hardly tell you how much I admire it. It is a positive comfort to me to have any feasible explanation of a difficulty that has always been haunting me, and I shall never be able to give it up till a better one supplies its place,--and that I think hardly possible. You have now fairly beaten Spencer on his own ground, for he really offered no solution of the difficulties of the problem. The incomprehensible minuteness and vast numbers of the physiological germs or atoms (which themselves must be compounded of numbers of Spencer's physiological units) is the only difficulty; but that is only on a par with the difficulties in all conceptions of matter, space, motion, force, etc. As I understood Spencer, his physiological units were identical throughout each species, but slightly different in each different species; but no attempt was made to show how the identical form of the parent or ancestors came to be built up of such units. LETTER 219. TO A.R. WALLACE. Down, February 27th [1868]. You cannot well imagine how much I have been pleased by what you say about pangenesis. None of my friends will speak out, except to a certain extent Sir H. Holland, who found it very tough reading, but admits that some view "closely akin to it" will have to be admitted. Hooker, as far as I understand him, which I hardly do at present, seems to think that the hypothesis is little more than saying that organisms have such and such potentialities. What you say exactly and fully expresses my feelings--viz., that it is a relief to have some feasible explanation of the various facts, which can be given up as soon as any better hypothesis is found. It has certainly been an immense relief to my mind; for I have been stumbling over the subject for years, dimly seeing that some relation existed between the various classes of facts. I now hear from H. Spencer that his views quoted in my footnote refer to something quite distinct, as you seem to have perceived. (219/1. This letter is published in "Life and Letters," III., page 79.) LETTER 220. A.R. WALLACE TO CHARLES DARWIN. Hurstpierpoint, March 1st, 1868. ...Sir C. Lyell spoke to me as if he has greatly admired pangenesis. I am very glad H. Spencer at once acknowledges that his view was something quite distinct from yours. Although, as you know, I am a great admirer of his, I feel how completely his view failed to go to the root of the matter, as yours does. His explained nothing, though he was evidently struggling hard to find an explanation. Yours, as far as I can see, explains everything in growth and reproduction--though, of course, the mystery of life and consciousness remains as great as ever. Parts of the chapter on pangenesis I found hard reading, and have not quite mastered yet, and there are also throughout the discussions in Volume II. many bits of hard reading, on minute points which we, who have not worked experimentally at cultivation and crossing, as you have done, can hardly see the importance of, or their bearing on the general question. If I am asked, I may perhaps write an article on the book for some periodical, and, if so, shall do what I can to make "Pangenesis" appreciated... (220/1. In "Nature," May 25th, 1871, page 69, appeared a letter on pangenesis from Mr. A.C. Ranyard, dealing with the difficulty that the "sexual elements produced upon the scion" have not been shown to be affected by the stock. Mr. Darwin, in an annotated copy of this letter, disputes the accuracy of the statement, but adds: "THE BEST OBJECTION YET RAISED." He seems not to have used Mr. Ranyard's remarks in the 2nd edition of the "Variation of Animals and Plants," 1875.) LETTER 221. TO J.D. HOOKER. Down, May 21st [1868]. I know that you have been overworking yourself, and that makes you think that you are doing nothing in science. If this is the case (which I do not believe), your intellect has all run to letter-writing, for I never in all my life received a pleasanter one than your last. It greatly amused us all. How dreadfully severe you are on the Duke (221/1. The late Duke of Argyll, whose "Reign of Law" Sir J.D. Hooker had been reading.): I really think too severe, but then I am no fair judge, for a Duke, in my eyes, is no common mortal, and not to be judged by common rules! I pity you from the bottom of my soul about the address (221/2. Sir Joseph was President of the British Association at Norwich in 1868: see "Life and Letters," III., page 100. The reference to "Insular Floras" is to Sir Joseph's lecture at the Nottingham meeting of the British Association in 1866: see "Life and Letters," III., page 47.): it makes my flesh creep; but when I pitied you to Huxley, he would not join at all, and would only say that you did and delivered your Insular Flora lecture so admirably in every way that he would not bestow any pity on you. He felt certain that you would keep your head high up. Nevertheless, I wish to God it was all over for your sake. I think, from several long talks, that Huxley will give an excellent and original lecture on Geograph. Distrib. of birds. I have been working very hard--too hard of late--on Sexual Selection, which turns out a gigantic subject; and almost every day new subjects turn up requiring investigation and leading to endless letters and searches through books. I am bothered, also, with heaps of foolish letters on all sorts of subjects, but I am much interested in my subject, and sometimes see gleams of light. All my other letters have prevented me indulging myself in writing to you; but I suddenly found the locust grass (221/3. No doubt the plants raised from seeds taken from locust dung sent by Mr. Weale from South Africa. The case is mentioned in the fifth edition of the "Origin," published in 1869, page 439.) yesterday in flower, and had to despatch it at once. I suppose some of your assistants will be able to make the genus out without great trouble. I have done little in experiment of late, but I find that mignonette is absolutely sterile with pollen from the same plant. Any one who saw stamen after stamen bending upwards and shedding pollen over the stigmas of the same flower would declare that the structure was an admirable contrivance for self-fertilisation. How utterly mysterious it is that there should be some difference in ovules and contents of pollen-grains (for the tubes penetrate own stigma) causing fertilisation when these are taken from any two distinct plants, and invariably leading to impotence when taken from the same plant! By Jove, even Pan. (221/4. Pangenesis.) won't explain this. It is a comfort to me to think that you will be surely haunted on your death-bed for not honouring the great god Pan. I am quite delighted at what you say about my book, and about Bentham; when writing it, I was much interested in some parts, but latterly I thought quite as poorly of it as even the "Athenaeum." It ought to be read abroad for the sake of the booksellers, for five editions have come or are coming out abroad! I am ashamed to say that I have read only the organic part of Lyell, and I admire all that I have read as much as you. It is a comfort to know that possibly when one is seventy years old one's brain may be good for work. It drives me mad, and I know it does you too, that one has no time for reading anything beyond what must be read: my room is encumbered with unread books. I agree about Wallace's wonderful cleverness, but he is not cautious enough in my opinion. I find I must (and I always distrust myself when I differ from him) separate rather widely from him all about birds' nests and protection; he is riding that hobby to death. I never read anything so miserable as Andrew Murray's criticism on Wallace in the last number of his Journal. (221/5. See "Journal of Travel and Natural History," Volume I., No. 3, page 137, London, 1868, for Andrew Murray's "Reply to Mr. Wallace's Theory of Birds' Nests," which appeared in the same volume, page 73. The "Journal" came to an end after the publication of one volume for 1867-8.) I believe this Journal will die, and I shall not cry: what a contrast with the old "Natural History Review." LETTER 222. TO J.D. HOOKER. Freshwater, Isle of Wight, July 28th [1868]. I am glad to hear that you are going (222/1. In his Presidential Address at Norwich.) to touch on the statement that the belief in Natural Selection is passing away. I do not suppose that even the "Athenaeum" would pretend that the belief in the common descent of species is passing away, and this is the more important point. This now almost universal belief in the evolution (somehow) of species, I think may be fairly attributed in large part to the "Origin." It would be well for you to look at the short Introduction of Owen's "Anat. of Invertebrates," and see how fully he admits the descent of species. Of the "Origin," four English editions, one or two American, two French, two German, one Dutch, one Italian, and several (as I was told) Russian editions. The translations of my book on "Variation under Domestication" are the results of the "Origin;" and of these two English, one American, one German, one French, one Italian, and one Russian have appeared, or will soon appear. Ernst Hackel wrote to me a week or two ago, that new discussions and reviews of the "Origin" are continually still coming out in Germany, where the interest on the subject certainly does not diminish. I have seen some of these discussions, and they are good ones. I apprehend that the interest on the subject has not died out in North America, from observing in Professor and Mrs. Agassiz's Book on Brazil how exceedingly anxious he is to destroy me. In regard to this country, every one can judge for himself, but you would not say interest was dying out if you were to look at the last number of the "Anthropological Review," in which I am incessantly sneered at. I think Lyell's "Principles" will produce a considerable effect. I hope I have given you the sort of information which you want. My head is rather unsteady, which makes my handwriting worse than usual. If you argue about the non-acceptance of Natural Selection, it seems to me a very striking fact that the Newtonian theory of gravitation, which seems to every one now so certain and plain, was rejected by a man so extraordinarily able as Leibnitz. The truth will not penetrate a preoccupied mind. Wallace (222/2. Wallace, "Westminster Review," July, 1867. The article begins: "There is no more convincing proof of the truth of a comprehensive theory, than its power of absorbing and finding a place for new facts, and its capability of interpreting phenomena, which had been previously looked upon as unaccountable anomalies..." Mr. Wallace illustrates his statement that "a false theory will never stand this test," by Edward Forbes' "polarity" speculations (see page 84 of the present volume) and Macleay's "Circular" and "Quinarian System" published in his "Horae Entomologicae," 1821, and developed by Swainson in the natural history volumes of "Lardner's Cabinet Cyclopaedia." Mr. Wallace says that a "considerable number of well-known naturalists either spoke approvingly of it, or advocated similar principles, and for a good many years it was decidedly in the ascendant...yet it quite died out in a few short years, its very existence is now a matter of history, and so rapid was its fall that...Swainson, perhaps, lived to be the last man who believed in it. Such is the course of a false theory. That of a true one is very different, as may be well seen by the progress of opinion on the subject of Natural Selection." Here, (page 3) follows a passage on the overwhelming importance of Natural Selection, underlined with apparent approval in Mr. Darwin's copy of the review.), in the "Westminster Review," in an article on Protection has a good passage, contrasting the success of Natural Selection and its growth with the comprehension of new classes of facts (222/3. This rather obscure phrase may be rendered: "its power of growth by the absorption of new facts."), with false theories, such as the Quinarian Theory, and that of Polarity, by poor Forbes, both of which were promulgated with high advantages and the first temporarily accepted. LETTER 223. TO G.H. LEWES. (223/1. The following is printed from a draft letter inscribed by Mr. Darwin "Against organs having been formed by direct action of medium in distinct organisms. Chiefly luminous and electric organs and thorns." The draft is carelessly written, and all but illegible.) August 7th, 1868. If you mean that in distinct animals, parts or organs, such for instance as the luminous organs of insects or the electric organs of fishes, are wholly the result of the external and internal conditions to which the organs have been subjected, in so direct and inevitable a manner that they could be developed whether of use or not to their possessor, I cannot admit [your view]. I could almost as soon admit that the whole structure of, for instance, a woodpecker, had thus originated; and that there should be so close a relation between structure and external circumstances which cannot directly affect the structure seems to me to [be] inadmissible. Such organs as those above specified seem to me much too complex and generally too well co-ordinated with the whole organisation, for the admission that they result from conditions independently of Natural Selection. The impression which I have taken, studying nature, is strong, that in all cases, if we could collect all the forms which have ever lived, we should have a close gradation from some most simple beginning. If similar conditions sufficed, without the aid of Natural Selection, to give similar parts or organs, independently of blood relationship, I doubt much whether we should have that striking harmony between the affinities, embryological development, geographical distribution, and geological succession of all allied organisms. We should be much more puzzled than we now are how to class, in a natural method, many forms. It is puzzling enough to distinguish between resemblance due to descent and to adaptation; but (fortunately for naturalists), owing to the strong power of inheritance, and to excessively complex causes and laws of variability, when the same end or object has been gained, somewhat different parts have generally been modified, and modified in a different manner, so that the resemblances due to descent and adaptation can commonly be distinguished. I should just like to add, that we may understand each other, how I suppose the luminous organs of insects, for instance, to have been developed; but I depend on conjectures, for so few luminous insects exist that we have no means of judging, by the preservation to the present day of slightly modified forms, of the probable gradations through which the organs have passed. Moreover, we do not know of what use these organs are. We see that the tissues of many animals, [as] certain centipedes in England, are liable, under unknown conditions of food, temperature, etc., to become occasionally luminous; just like the [illegible]: such luminosity having been advantageous to certain insects, the tissues, I suppose, become specialised for this purpose in an intensified degree; in certain insects in one part, in other insects in other parts of the body. Hence I believe that if all extinct insect-forms could be collected, we should have gradations from the Elateridae, with their highly and constantly luminous thoraxes, and from the Lampyridae, with their highly luminous abdomens, to some ancient insects occasionally luminous like the centipede. I do not know, but suppose that the microscopical structure of the luminous organs in the most different insects is nearly the same; and I should attribute to inheritance from a common progenitor, the similarity of the tissues, which under similar conditions, allowed them to vary in the same manner, and thus, through Natural Selection for the same general purpose, to arrive at the same result. Mutatis mutandis, I should apply the same doctrine to the electric organs of fishes; but here I have to make, in my own mind, the violent assumption that some ancient fish was slightly electrical without having any special organs for the purpose. It has been stated on evidence, not trustworthy, that certain reptiles are electrical. It is, moreover, possible that the so-called electric organs, whilst in a condition not highly developed, may have subserved some distinct function: at least, I think, Matteucci could detect no pure electricity in certain fishes provided with the proper organs. In one of your letters you alluded to nails, claws, hoofs, etc. From their perfect coadaptation with the whole rest of the organisation, I cannot admit that they would have been formed by the direct action of the conditions of life. H. Spencer's view that they were first developed from indurated skin, the result of pressure on the extremities, seems to me probable. In regard to thorns and spines I suppose that stunted and [illegible] hardened processes were primarily left by the abortion of various appendages, but I must believe that their extreme sharpness and hardness is the result of fluctuating variability and "the survival of the fittest." The precise form, curvature and colour of the thorns I freely admit to be the result of the laws of growth of each particular plant, or of their conditions, internal and external. It would be an astounding fact if any varying plant suddenly produced, without the aid of reversion or selection, perfect thorns. That Natural Selection would tend to produce the most formidable thorns will be admitted by every one who has observed the distribution in South America and Africa (vide Livingstone) of thorn-bearing plants, for they always appear where the bushes grow isolated and are exposed to the attacks of mammals. Even in England it has been noticed that all spine-bearing and sting-bearing plants are palatable to quadrupeds, when the thorns are crushed. With respect to the Malayan climbing Palm, what I meant to express is that the admirable hooks were perhaps not first developed for climbing; but having been developed for protection were subsequently used, and perhaps further modified for climbing. LETTER 224. TO J.D. HOOKER. Down, September 8th [1868]. About the "Pall Mall." (224/1. "Pall Mall Gazette," August 22nd, 1868. In an article headed "Dr. Hooker on Religion and Science," and referring to the British Association address, the writer objects to any supposed opposition between religion and science. "Religion," he says, "is your opinion upon one set of subjects, science your opinion upon another set of subjects." But he forgets that on one side we have opinions assumed to be revealed truths; and this is a condition which either results in the further opinion that those who bring forward irreconcilable facts are more or less wicked, or in a change of front on the religious side, by which theological opinion "shifts its ground to meet the requirements of every new fact that science establishes, and every old error that science exposes" (Dr. Hooker as quoted by the "Pall Mall"). If theologians had been in the habit of recognising that, in the words of the "Pall Mall" writer, "Science is a general name for human knowledge in its most definite and general shape, whatever may be the object of that knowledge," probably Sir Joseph Hooker's remarks would never have been made.) I do not agree that the article was at all right; it struck me as monstrous (and answered on the spot by the "Morning Advertiser") that religion did not attack science. When, however, I say not at all right, I am not sure whether it would not be wisest for scientific men quite to ignore the whole subject of religion. Goldwin Smith, who has been lunching here, coming with the Nortons (son of Professor Norton and friend of Asa Gray), who have taken for four months Keston Rectory, was strongly of opinion it was a mistake. Several persons have spoken strongly to me as very much admiring your address. For chance of you caring to see yourself in a French dress, I send a journal; also with a weak article by Agassiz on Geographical Distribution. Berkeley has sent me his address (224/2. The Rev. M.J. Berkeley was President of Section D at Norwich in 1868.), so I have had a fair excuse for writing to him. I differ from you: I could hardly bear to shake hands with the "Sugar of Lead" (224/3. "You know Mrs. Carlyle said that Owen's sweetness reminded her of sugar of lead." (Huxley to Tyndall, May 13th, 1887: Huxley's "Life," II., page 167.), which I never heard before: it is capital. I am so very glad you will come here with Asa Gray, as if I am bad he will not be dull. We shall ask the Nortons to come to dinner. On Saturday, Wallace (and probably Mrs. W.), J. Jenner Weir (a very good man), and Blyth, and I fear not Bates, are coming to stay the Sunday. The thought makes me rather nervous; but I shall enjoy it immensely if it does not kill me. How I wish it was possible for you to be here! LETTER 225. TO M.J. BERKELEY. Down, September 7th, 1868. I am very much obliged to you for having sent me your address (225/1. Address to Section D of the British Association. ("Brit. Assoc. Report," Norwich meeting, 1868, page 83.))...for I thus gain a fair excuse for troubling you with this note to thank you for your most kind and extremely honourable notice of my works. When I tell you that ever since I was an undergraduate at Cambridge I have felt towards you the most unfeigned respect, from all that I continually heard from poor dear Henslow and others of your great knowledge and original researches, you will believe me when I say that I have rarely in my life been more gratified than by reading your address; though I feel that you speak much too strongly of what I have done. Your notice of pangenesis (225/3. "It would be unpardonable to finish these somewhat desultory remarks without adverting to one of the most interesting subjects of the day,--the Darwinian doctrine of pangenesis...Like everything which comes from the pen of a writer whom I have no hesitation, so far as my judgment goes, in considering as by far the greatest observer of our age, whatever may be thought of his theories when carried out to their extreme results, the subject demands a careful and impartial consideration." (Berkeley, page 86.)) has particularly pleased me, for it has been generally neglected or disliked by my friends; yet I fully expect that it will some day be more successful. I believe I quite agree with you in the manner in which the cast-off atoms or so-called gemmules probably act (225/4. "Assuming the general truth of the theory that molecules endowed with certain attributes are cast off by the component cells of such infinitesimal minuteness as to be capable of circulating with the fluids, and in the end to be present in the unimpregnated embryo-cell and spermatozoid...it seems to me far more probable that they should be capable under favourable circumstances of exercising an influence analogous to that which is exercised by the contents of the pollen-tube or spermatozoid on the embryo-sac or ovum, than that these particles should be themselves developed into cells" (Berkeley, page 87).): I have never supposed that they were developed into free cells, but that they penetrated other nascent cells and modified their subsequent development. This process I have actually compared with ordinary fertilisation. The cells thus modified, I suppose cast off in their turn modified gemmules, which again combine with other nascent cells, and so on. But I must not trouble you any further. LETTER 226. TO AUGUST WEISMANN. Down, October 22nd, 1868. I am very much obliged for your kind letter, and I have waited for a week before answering it in hopes of receiving the "kleine Schrift" (226/1. The "kleine Schrift" is "Ueber die Berechtigung der Darwin'schen Theorie," Leipzig, 1868. The "Anhang" is "Ueber den Einfluss der Wanderung und raumlichen Isolirung auf die Artbilding.") to which you allude; but I fear it is lost, which I am much surprised at, as I have seldom failed to receive anything sent by the post. As I do not know the title, and cannot order a copy, I should be very much obliged if you can spare another. I am delighted that you, with whose name I am familiar, should approve of my work. I entirely agree with what you say about each species varying according to its own peculiar laws; but at the same time it must, I think, be admitted that the variations of most species have in the lapse of ages been extremely diversified, for I do not see how it can be otherwise explained that so many forms have acquired analogous structures for the same general object, independently of descent. I am very glad to hear that you have been arguing against Nageli's law of perfectibility, which seems to me superfluous. Others hold similar views, but none of them define what this "perfection" is which cannot be gradually attained through Natural Selection. I thought M. Wagner's first pamphlet (226/2. Wagner's first essay, "Die Darwin'sche Theorie und das Migrationsgesetz," 1868, is a separately published pamphlet of 62 pages. In the preface the author states that it is a fuller version of a paper read before the Royal Academy of Science at Munich in March 1868. We are not able to say which of Wagner's writings is referred to as the second pamphlet; his second well-known essay, "Ueber den Einfluss der Geogr. Isolirung," etc., is of later date, viz., 1870.) (for I have not yet had time to read the second) very good and interesting; but I think that he greatly overrates the necessity for emigration and isolation. I doubt whether he has reflected on what must occur when his forms colonise a new country, unless they vary during the very first generation; nor does he attach, I think, sufficient weight to the cases of what I have called unconscious selection by man: in these cases races are modified by the preservation of the best and the destruction of the worst, without any isolation. I sympathise with you most sincerely on the state of your eyesight: it is indeed the most fearful evil which can happen to any one who, like yourself, is earnestly attached to the pursuit of natural knowledge. LETTER 227. TO F. MULLER. Down, March 18th [1869]. Since I wrote a few days ago and sent off three copies of your book, I have read the English translation (227/1. "Facts and Arguments for Darwin." See "Life and Letters," III., page 37.), and cannot deny myself the pleasure of once again expressing to you my warm admiration. I might, but will not, repeat my thanks for the very honourable manner in which you often mention my name; but I can truly say that I look at the publication of your essay as one of the greatest honours ever conferred on me. Nothing can be more profound and striking than your observations on development and classification. I am very glad that you have added your justification in regard to the metamorphoses of insects; for your conclusion now seems in the highest degree probable. (227/2. See "Facts and Arguments for Darwin," page 119 (note), where F. Muller gives his reasons for the belief that the "complete metamorphosis" of insects was not a character of the form from which insects have sprung: his argument largely depends on considerations drawn from the study of the neuroptera.) I have re-read many parts, especially that on cirripedes, with the liveliest interest. I had almost forgotten your discussion on the retrograde development of the Rhizocephala. What an admirable illustration it affords of my whole doctrine! A man must indeed be a bigot in favour of separate acts of creation if he is not staggered after reading your essay; but I fear that it is too deep for English readers, except for a select few. LETTER 228. TO A.R. WALLACE. March 27th [1869]. I have lately (i.e., in new edition of the "Origin") (228/1. Fifth edition, 1869, pages 150-57.) been moderating my zeal, and attributing much more to mere useless variability. I did think I would send you the sheet, but I daresay you would not care to see it, in which I discuss Nageli's Essay on Natural Selection not affecting characters of no functional importance, and which yet are of high classificatory importance. Hooker is pretty well satisfied with what I have said on this head. LETTER 229. TO J.D. HOOKER. Caerdeon, Barmouth, North Wales, July 24th [1869]. We shall be at home this day week, taking two days on the journey, and right glad I shall be. The whole has been a failure to me, but much enjoyment to the young...My wife has ailed a good deal nearly all the time; so that I loathe the place, with all its beauty. I was glad to hear what you thought of F. Muller, and I agree wholly with you. Your letter came at the nick of time, for I was writing on the very day to Muller, and I passed on your approbation of Chaps. X. and XI. Some time I should like to borrow the "Transactions of the New Zealand Institute," so as to read Colenso's article. (229/1. Colenso, "On the Maori Races of New Zealand." "N.Z. Inst. Trans." 1868, Pt. 3.) You must read Huxley v. Comte (229/2. "The Scientific Aspects of Positivism." "Fortnightly Review," 1869, page 652, and "Lay Sermons," 1870, page 162. This was a reply to Mr. Congreve's article, "Mr. Huxley on M. Comte," published in the April number of the "Fortnightly," page 407, which had been written in criticism of Huxley's article in the February number of the "Fortnightly," page 128, "On the Physical Basis of Life."); he never wrote anything so clever before, and has smashed everybody right and left in grand style. I had a vague wish to read Comte, and so had George, but he has entirely cured us of any such vain wish. There is another article (229/3. "North British Review," Volume 50, 1869: "Geological Time," page 406. The papers reviewed are Sir William Thomson, "Trans. R. Soc. Edin." 1862; "Phil. Mag." 1863; Thomson and Tait, "Natural Philosophy," Volume I., App. D; Sir W. Thomson, "Proc. R. Soc. Edin." 1865; "Trans. Geol. Soc. Glasgow," 1868 and 1869; "Macmillan's Mag." 1862; Prof. Huxley, Presidential Address, "Geol. Soc. London," February, 1869; Dr. Hooker, Presidential Address, "Brit. Assoc." Norwich, 1868. Also the review on the "Origin" in the "North British Review," 1867, by Fleeming Jenkin, and an article in the "Pall Mall Gazette," May 3rd, 1869. The author treats the last-named with contempt as the work of an anonymous journalist, apparently unconscious of his own similar position.) just come out in last "North British," by some great mathematician, which is admirably done; he has a severe fling at you (229/4. The author of the "North British" article appears to us, at page 408, to misunderstand or misinterpret Sir J.D. Hooker's parable on "underpinning." See "Life and Letters," III., page 101 (note). Sir Joseph is attacked with quite unnecessary vehemence on another point at page 413.), but the article is directed against Huxley and for Thomson. This review shows me--not that I required being shown--how devilish a clever fellow Huxley is, for the reviewer cannot help admiring his abilities. There are some good specimens of mathematical arrogance in the review, and incidentally he shows how often astronomers have arrived at conclusions which are now seen to be mistaken; so that geologists might truly answer that we must be slow in admitting your conclusions. Nevertheless, all uniformitarians had better at once cry "peccavi,"--not but what I feel a conviction that the world will be found rather older than Thomson makes it, and far older than the reviewer makes it. I am glad I have faced and admitted the difficulty in the last edition of the "Origin," of which I suppose you received, according to order, a copy. LETTER 230. TO J.D. HOOKER. Down, August 7th [1869]. There never was such a good man as you for telling me things which I like to hear. I am not at all surprised that Hallett has found some varieties of wheat could not be improved in certain desirable qualities as quickly as at first. All experience shows this with animals; but it would, I think, be rash to assume, judging from actual experience, that a little more improvement could not be got in the course of a century, and theoretically very improbable that after a few thousands [of years] rest there would not be a start in the same line of variation. What astonishes me as against experience, and what I cannot believe, is that varieties already improved or modified do not vary in other respects. I think he must have generalised from two or three spontaneously fixed varieties. Even in seedlings from the same capsule some vary much more than others; so it is with sub-varieties and varieties. (230/1. In a letter of August 13th, 1869, Sir J.D. Hooker wrote correcting Mr. Darwin's impression: "I did not mean to imply that Hallett affirmed that all variation stopped--far from it: he maintained the contrary, but if I understand him aright, he soon arrives at a point beyond which any further accumulation in the direction sought is so small and so slow that practically a fixity of type (not absolute fixity, however) is the result.") It is a grand fact about Anoplotherium (230/2. This perhaps refers to the existence of Anoplotherium in the S. American Eocene formation: it is one of the points in which the fauna of S. America resembles Europe rather than N. America. (See Wallace "Geographical Distribution," I., page 148.)), and shows how even terrestrial quadrupeds had time formerly to spread to very distinct regions. At each epoch the world tends to get peopled pretty uniformly, which is a blessing for Geology. The article in "N. British Review" (230/3. See Letter 229.) is well worth reading scientifically; George D. and Erasmus were delighted with it. How the author does hit! It was a euphuism to speak of a fling at you: it was a kick. He is very unfair to Huxley, and accuses him of "quibbling," etc.; yet the author cannot help admiring him extremely. I know I felt very small when I finished the article. You will be amused to observe that geologists have all been misled by Playfair, who was misled by two of the greatest mathematicians! And there are other such cases; so we could turn round and show your reviewer how cautious geologists ought to be in trusting mathematicians. There is another excellent original article, I feel sure by McClennan, on Primeval Man, well worth reading. I do not quite agree about Sabine: he is unlike every other soldier or sailor I ever heard of if he would not put his second leg into the tomb with more satisfaction as K.C.B. than as a simple man. I quite agree that the Government ought to have made him long ago, but what does the Government know or care for Science? So much for your splenditious letter. LETTER 231. TO J.D. HOOKER. Down, August 14th [1869?] I write one line to tell you that you are a real good man to propose coming here for a Sunday after Exeter. Do keep to this good intention...I am sure Exeter and your other visit will do you good. I often wonder how you stand all your multifarious work. I quite agree about the folly of the endless subscriptions for dead men; but Faraday is an exception, and if you will pay three guineas for me, it will save me some trouble; but it will be best to enclose a cheque, which, as you will see, must be endorsed. If you read the "North British Review," you will like to know that George has convinced me, from correspondence in style, and spirit, that the article is by Tait, the co-worker with Thomson. I was much surprised at the leaves of Drosophyllum being always rolled backwards at their tips, but did not know that it was a unique character. (PLATE: SIR J.D. HOOKER, 1870? From a photograph by Wallich.) LETTER 232. TO J.D. HOOKER. Down, November 13th [1869]. I heard yesterday from a relation who had seen in a newspaper that you were C.B. I must write one line to say "Hurrah," though I wish it had been K.C.B., as it assuredly ought to have been; but I suppose they look at K.C.B. before C.B. as a dukedom before an earldom. We had a very successful week in London, and I was unusually well and saw a good many persons, which, when well, is a great pleasure to me. I had a jolly talk with Huxley, amongst others. And now I am at the same work as before, and shall be for another two months--namely, putting ugly sentences rather straighter; and I am sick of the work, and, as the subject is all on sexual selection, I am weary of everlasting males and females, cocks and hens. It is a shame to bother you, but I should like some time to hear about the C.B. affair. I have read one or two interesting brochures lately--viz., Stirling the Hegelian versus Huxley and protoplasm; Tylor in "Journal of Royal Institute" on the survivals of old thought in modern civilisation. Farewell. I am as dull as a duck, both male and female. To Dr. Hooker, C.B., F.R.S. Dr. Hooker, K.C.B. (This looks better). P.S. I hear a good account of Bentham's last address (232/1. Presidential Address, chiefly on Geographical Distribution, delivered before the "Linn. Soc." May 24th, 1869.), which I am now going to read. I find that I have blundered about Bentham's address. Lyell was speaking about one that I read some months ago; but I read half of it again last night, and shall finish it. Some passages are either new or were not studied enough by me before. It strikes me as admirable, as it did on the first reading, though I differ in some few points. Such an address is worth its weight in gold, I should think, in making converts to our views. Lyell tells me that Bunbury has been wonderfully impressed with it, and he never before thought anything of our views on evolution. P.S. (2). I have just read, and like very much, your review of Schimper. (232/2. A review of Schimper's "Traite de Paleontologie Vegetale," the first portion of which was published in 1869. "Nature," November 11th, 1869, page 48.) LETTER 233. TO J.D. HOOKER. Down, November 19th [1869]. Thank you much for telling me all about the C.B., for I much wished to hear. It pleases me extremely that the Government have done this much; and as the K.C.B.'s are limited in number (which I did not know), I excuse it. I will not mention what you have told me to any one, as it would be Murchisonian. But what a shame it is to use this expression, for I fully believe that Murchison would take any trouble to get any token of honour for any man of science. I like all scientific periodicals, including poor "Scientific Opinion," and I think higher than you do of "Nature." Lord, what a rhapsody that was of Goethe, but how well translated; it seemed to me, as I told Huxley, as if written by the maddest English scholar. It is poetry, and can I say anything more severe? The last number of the "Academy" was splendid, and I hope it will soon come out fortnightly. I wish "Nature" would search more carefully all foreign journals and transactions. I am now reading a German thick pamphlet (233/1. "Die Abhangigheit der Pflanzengestalt von Klima und Boden. Ein Beitrag zur Lehre von der Enstehung und Verbreitung der Arten, etc." Festschrift zur 43 Versammlung Deutscher Naturforscher und Aertze in Innsbruck (Innsbruck, 1869).) by Kerner on Tubocytisus; if you come across it, look at the map of the distribution of the eighteen quasi-species, and at the genealogical tree. If the latter, as the author says, was constructed solely from the affinities of the forms, then the distribution is wonderfully interesting; we may see the very steps of the formation of a species. If you study the genealogical tree and map, you will almost understand the book. The two old parent connecting links just keep alive in two or three areas; then we have four widely extended species, their descendants; and from them little groups of newer descendants inhabiting rather small areas... LETTER 234. TO CAMILLE DARESTE. Down, November 20th, 1869. Dear Sir, I am glad that you are a candidate for the Chair of Physiology in Paris. As you are aware from my published works, I have always considered your investigations on the production of monstrosities as full of interest. No subject is at the present time more important, as far as my judgment goes, than the ascertaining by experiment how far structure can be modified by the direct action of changed conditions; and you have thrown much light on this subject. I observe that several naturalists in various parts of Europe have lately maintained that it is now of the highest interest for science to endeavour to lessen, as far as possible, our profound ignorance on the cause of each individual variation; and, as Is. Geoffroy St. Hilaire long ago remarked, monstrosities cannot be separated by any distinct line from slighter variations. With my best wishes for your success in obtaining the Professorship, and with sincere respect. I have the honour to remain, dear sir, Yours faithfully, CHARLES DARWIN. CHAPTER 1.V.--EVOLUTION, 1870-1882. LETTER 235. TO J. JENNER WEIR. Down, March 17th [1870]. It is my decided opinion that you ought to send an account to some scientific society, and I think to the Royal Society. (235/1. Mr. Jenner Weir's case is given in "Animals and Plants," Edition II., Volume I., page 435, and does not appear to have been published elsewhere. The facts are briefly that a horse, the offspring of a mare of Lord Mostyn's, which had previously borne a foal by a quagga, showed a number of quagga-like characters, such as stripes, low-growing mane, and elongated hoofs. The passage in "Animals and Plants," to which he directs Mr. Weir's attention in reference to Carpenter's objection, is in Edition I., Volume I., page 405: "It is a most improbable hypothesis that the mere blood of one individual should affect the reproductive organs of another individual in such a manner as to modify the subsequent offspring. The analogy from the direct action of foreign pollen on the ovarium and seed-coats of the mother plant strongly supports the belief that the male element acts directly on the reproductive organs of the female, wonderful as is this action, and not through the intervention of the crossed embryo." For references to Mr. Galton's experiments on transfusion of blood, see Letter 273.) I would communicate it if you so decide. You might give as a preliminary reason the publication in the "Transactions" of the celebrated Morton case and the pig case by Mr. Giles. You might also allude to the evident physiological importance of such facts as bearing on the theory of generation. Whether it would be prudent to allude to despised pangenesis I cannot say, but I fully believe pangenesis will have its successful day. Pray ascertain carefully the colour of the dam and sire. See about duns in my book ["Animals and Plants"], Volume I., page 55. The extension of the mane and form of hoofs are grand new facts. Is the hair of your horse at all curly? for [an] observed case [is] given by me (Volume II., page 325) from Azara of correlation of forms of hoof with curly hairs. See also in my book (Volume I., page 55; Volume II., page 41) how exceedingly rare stripes are on the faces of horses in England. Give the age of your horse. You are aware that Dr. Carpenter and others have tried to account for the effects of a first impregnation from the influence of the blood of the crossed embryo; but with physiologists who believe that the reproductive elements are actually formed by the reproductive glands, this view is inconsistent. Pray look at what I have said in "Domestic Animals" (Volume I., pages 402-5) against this doctrine. It seems to me more probable that the gemmules affect the ovaria alone. I remember formerly speculating, like you, on the assertion that wives grow like their husbands; but how impossible to eliminate effects of imitation and same habits of life, etc. Your letter has interested me profoundly. P.S.--Since publishing I have heard of additional cases--a very good one in regard to Westphalian pigs crossed by English boar, and all subsequent offspring affected, given in "Illust. Landwirth-Zeitung," 1868, page 143. I have shown that mules are often striped, though neither parent may be striped,--due to ancient reversion. Now, Fritz Muller writes to me from S. Brazil: "I have been assured, by persons who certainly never had heard of Lord Morton's mare, that mares which have borne hybrids to an ass are particularly liable to produce afterwards striped ass-colts." So a previous fertilisation apparently gives to the subsequent offspring a tendency to certain characters, as well as characters actually possessed by the first male. In the reprint (not called a second edition) of my "Domestic Animals" I give a good additional case of subsequent progeny of hairless dog being hairy from effects of first impregnation. P.S. 2nd. The suggestion, no doubt, is superfluous, but you ought, I think, to measure extension of mane beyond a line joining front or back of ears, and compare with horse. Also the measure (and give comparison with horse), length, breadth, and depth of hoofs. LETTER 236. TO J.D. HOOKER. Down, July 12th [1870]. Your conclusion that all speculation about preordination is idle waste of time is the only wise one; but how difficult it is not to speculate! My theology is a simple muddle; I cannot look at the universe as the result of blind chance, yet I can see no evidence of beneficent design or indeed of design of any kind, in the details. As for each variation that has ever occurred having been preordained for a special end, I can no more believe in it than that the spot on which each drop of rain falls has been specially ordained. Spontaneous generation seems almost as great a puzzle as preordination. I cannot persuade myself that such a multiplicity of organisms can have been produced, like crystals, in Bastian's (236/1. On September 2nd, 1872, Mr. Darwin wrote to Mr. Wallace, in reference to the latter's review of "The Beginnings of Life," by H.C. Bastian (1872), in "Nature," 1872, pages 284-99: "At present I should prefer any mad hypothesis, such as that every disintegrated molecule of the lowest forms can reproduce the parent-form; and that these molecules are universally distributed, and that they do not lose their vital power until heated to such a temperature that they decompose like dead organic particles.") solutions of the same kind. I am astonished that, as yet, I have met with no allusion to Wyman's positive statement (236/2. "Observations and Experiments on Living Organisms in Heated Water," by Jeffries Wyman, Prof. of Anatomy, Harvard Coll. ("Amer. Journ. Sci." XLIV., 1867, page 152.) Solutions of organic matter in hermetically sealed flasks were immersed in boiling water for various periods. "No infusoria of any kind appeared if the boiling was prolonged beyond a period of five hours.") that if the solutions are boiled for five hours no organisms appear; yet, if my memory serves me, the solutions when opened to air immediately became stocked. Against all evidence, I cannot avoid suspecting that organic particles (my "gemmules" from the separate cells of the lower creatures!) will keep alive and afterwards multiply under proper conditions. What an interesting problem it is. LETTER 237. TO W.B. TEGETMEIER. Down, July 15th [1870]. It is very long since I have heard from you, and I am much obliged for your letter. It is good news that you are going to bring out a new edition of your Poultry book (237/1. "The Poultry Book," 1872.), and you are quite at liberty to use all my materials. Thanks for the curious case of the wild duck variation: I have heard of other instances of a tendency to vary in one out of a large litter or family. I have too many things in hand at present to profit by your offer of the loan of the American Poultry book. Pray keep firm to your idea of working out the subject of analogous variations (237/2. "By this term I mean that similar characters occasionally make their appearance in the several varieties or races descended from the same species, and more rarely in the offspring of widely distinct species" ("Animals and Plants," II., Edition II., page 340).) with pigeons; I really think you might thus make a novel and valuable contribution to science. I can, however, quite understand how much your time must be occupied with the never-ending, always-beginning editorial cares. I keep much as usual, and crawl on with my work. LETTER 238. TO J.D. HOOKER. Down, September 27th [1870]. Yours was a splendid letter, and I was very curious to hear something about the Liverpool meeting (238/1. Mr. Huxley was President of the British Association at Liverpool in 1870. His Presidential Address on "Biogenesis and Abiogenesis" is reprinted in his collected Essays, VIII., page 229. Some account of the meeting is given in Huxley's "Life and Letters," Volume I., pages 332, 336.), which I much wished to be successful for Huxley's sake. I am surprised that you think his address would not have been clear to the public; it seemed to me as clear as water. The general line of his argument might have been answered by the case of spontaneous combustion: tens of thousands of cases of things having been seen to be set on fire would be no true argument against any one who maintained that flames sometimes spontaneously burst forth. I am delighted at the apotheosis of Sir Roderick; I can fancy what neat and appropriate speeches he would make to each nobleman as he entered the gates of heaven. You ask what I think about Tyndall's lecture (238/2. Tyndall's lecture was "On the Scientific Uses of the Imagination."): it seemed to me grand and very interesting, though I could not from ignorance quite follow some parts, and I longed to tell him how immensely it would have been improved if all the first part had been made very much less egotistical. George independently arrived at the same conclusion, and liked all the latter part extremely. He thought the first part not only egotistical, but rather clap-trap. How well Tyndall puts the "as if" manner of philosophising, and shows that it is justifiable. Some of those confounded Frenchmen have lately been pitching into me for using this form of proof or argument. I have just read Rolleston's address in "Nature" (238/3. Presidential Address to the Biological Section, British Association, 1870. "Nature," September 22nd, 1870, page 423. Rolleston referred to the vitality of seeds in soil, a subject on which Darwin made occasional observations. See "Life and Letters," II., page 65.): his style is quite unparalleled! I see he quotes you about seed, so yesterday I went and observed more carefully the case given in the enclosed paper, which perhaps you might like to read and burn. How true and good what you say about Lyell. He is always the same; Dohrn was here yesterday, and was remarking that no one stood higher in the public estimation of Germany than Lyell. I am truly and profoundly glad that you are thinking of some general work on Geographical Distribution, or so forth; I hope to God that your incessant occupations may not interrupt this intention. As for my book, I shall not have done the accursed proofs till the end of November (238/4. The proofs of the "Descent of Man" were finished on January 15th, 1871.): good Lord, what a muddled head I have got on my wretched old shoulders. LETTER 239. TO H. SETTEGAST. Down, September 29th, 1870. I am very much obliged for your kind letter and present of your beautiful volume. (239/1. "Die Thierzucht," 1868.) Your work is not new to me, for I heard it so highly spoken of that I procured a copy of the first edition. It was a great gratification to me to find a man who had long studied with a philosophical spirit our domesticated animals, and who was highly competent to judge, agreeing to a large extent with my views. I regretted much that I had not known your work when I published my last volumes. I am surprised and pleased to hear that science is not quite forgotten under the present exciting state of affairs. Every one whom I know in England is an enthusiastic wisher for the full and complete success of Germany. P.S. I will give one of my two copies of your work to some public scientific library in London. LETTER 240. TO THE EDITOR OF THE "PALL MALL GAZETTE." Down, March 24th [1871]. Mr. Darwin presents his compliments to the Editor, and would be greatly obliged if he would address and post the enclosed letter to the author of the two admirable reviews of the "Descent of Man." (240/1. The notices of the "Descent of Man," published in the "Pall Mall Gazette" of March 20th and 21st, 1871, were by Mr. John Morley. We are indebted to the Editor of the "Pall Mall Gazette" for kindly allowing us to consult his file of the journal.) LETTER 241. TO JOHN MORLEY. Down, March 24th, 1871. From the spirit of your review in the "Pall Mall Gazette" of my last book, which has given me great pleasure, I have thought that you would perhaps inform me on one point, withholding, if you please, your name. You say that my phraseology on beauty is "loose scientifically, and philosophically most misleading." (241/1. "Mr. Darwin's work is one of those rare and capital achievements of intellect which effect a grave modification throughout all the highest departments of the realm of opinion...There is throughout the description and examination of Sexual Selection a way of speaking of beauty, which seems to us to be highly unphilosophical, because it assumes a certain theory of beauty, which the most competent modern thinkers are too far from accepting, to allow its assumption to be quite judicious...Why should we only find the aesthetic quality in birds wonderful, when it happens to coincide with our own? In other words, why attribute to them conscious aesthetic qualities at all? There is no more positive reason for attributing aesthetic consciousness to the Argus pheasant than there is for attributing to bees geometric consciousness of the hexagonal prisms and rhombic plates of the hive which they so marvellously construct. Hence the phraseology which Mr. Darwin employs in this part of the subject, though not affecting the degree of probability which may belong to this theory, seems to us to be very loose scientifically, and philosophically most misleading."--"Pall Mall Gazette.") This is not at all improbable, as it is almost a lifetime since I attended to the philosophy of aesthetics, and did not then think that I should ever make use of my conclusions. Can you refer me to any one or two books (for my power of reading is not great) which would illumine me? or can you explain in one or two sentences how I err? Perhaps it would be best for me to explain what I mean by the sense of beauty in its lowest stage of development, and which can only apply to animals. When an intense colour, or two tints in harmony, or a recurrent and symmetrical figure please the eye, or a single sweet note pleases the ear, I call this a sense of beauty; and with this meaning I have spoken (though I now see in not a sufficiently guarded manner) of a taste for the beautiful being the same in mankind (for all savages admire bits of bright cloth, beads, plumes, etc.) and in the lower animals. If the blue and yellow plumage of a macaw (241/2. "What man deems the horrible contrasts of yellow and blue attract the macaw, while ball-and-socket-plumage attracts the Argus pheasant"--"Pall Mall Gazette," March 21st, 1871, page 1075.) pleases the eye of this bird, I should say that it had a sense of beauty, although its taste was bad according to our standard. Now, will you have the kindness to tell me how I can learn to see the error of my ways? Of course I recognise, as indeed I have remarked in my book, that the sense of beauty in the case of scenery, pictures, etc., is something infinitely complex, depending on varied associations and culture of the mind. From a very interesting review in the "Spectator," and from your and Wallace's review, I perceive that I have made a great oversight in not having said what little I could on the acquisition of the sense for the beautiful by man and the lower animals. It would indeed be an immense advantage to an author if he could read such criticisms as yours before publishing. At page 11 of your review you accidentally misquote my words placed by you within inverted commas, from my Volume II., page 354: I say that "man cannot endure any great change," and the omitted words "any great" make all the difference in the discussion. (241/3. "Mr. Darwin tells us, and gives us excellent reasons for thinking, that 'the men of each race prefer what they are accustomed to behold; they cannot endure change.' Yet is there not an inconsistency between this fact and the other that one race differs from another exactly because novelties presented themselves, and were eagerly seized and propagated?") Permit me to add a few other remarks. I believe your criticism is quite just about my deficient historic spirit, for I am aware of my ignorance in this line. (241/4. "In the historic spirit, however, Mr. Darwin must fairly be pronounced deficient. When, for instance, he speaks of the 'great sin of slavery' having been general among primitive nations, he forgets that, though to hold a slave would be a sinful degradation to a European to-day, the practice of turning prisoners of war into slaves, instead of butchering them, was not a sin at all, but marked a decided improvement in human manners.") On the other hand, if you should ever be led to read again Chapter III., and especially Chapter V., I think you will find that I am not amenable to all your strictures; though I felt that I was walking on a path unknown to me and full of pitfalls; but I had the advantage of previous discussions by able men. I tried to say most emphatically that a great philosopher, law-giver, etc., did far more for the progress of mankind by his writings or his example than by leaving a numerous offspring. I have endeavoured to show how the struggle for existence between tribe and tribe depends on an advance in the moral and intellectual qualities of the members, and not merely on their capacity of obtaining food. When I speak of the necessity of a struggle for existence in order that mankind should advance still higher in the scale, I do not refer to the MOST, but "to the MORE highly gifted men" being successful in the battle for life; I referred to my supposition of the men in any country being divided into two equal bodies--viz., the more and the less highly gifted, and to the former on an average succeeding best. But I have much cause to apologise for the length of this ill-expressed letter. My sole excuse is the extraordinary interest which I have felt in your review, and the pleasure which I have experienced in observing the points which have attracted your attention. I must say one word more. Having kept the subject of sexual selection in my mind for very many years, and having become more and more satisfied with it, I feel great confidence that as soon as the notion is rendered familiar to others, it will be accepted, at least to a much greater extent than at present. With sincere respect and thanks... LETTER 242. TO JOHN MORLEY. Down, April 14th [1871]. As this note requires no answer, I do not scruple to write a few lines to say how faithful and full a resume you have given of my notions on the moral sense in the "Pall Mall," and to make a few extenuating or explanatory remarks. (242/1. "What is called the question of the moral sense is really two: how the moral faculty is acquired, and how it is regulated. Why do we obey conscience or feel pain in disobeying it? And why does conscience prescribe one kind of action and condemn another kind? To put it more technically, there is the question of the subjective existence of conscience, and there is the question of its objective prescriptions. First, why do I think it obligatory to do my duty? Second, why do I think it my duty to do this and not do that? Although, however, the second question ought to be treated independently, for reasons which we shall presently suggest, the historical answer to it, or the various grounds on which men have identified certain sorts of conduct with duty, rather than conduct of the opposite sorts, throws light on the other question of the conditions of growth of the idea of duty as a sovereign and imperial director. Mr. Darwin seems to us not to have perfectly recognised the logical separation between the two sides of the moral sense question. For example, he says (i. 97) that 'philosophers of the derivative school of morals formerly assumed that the foundation of morality lay in a form of Selfishness; but more recently in the Greatest Happiness principle.' But Mr. Mill, to whom Mr. Darwin refers, has expressly shown that the Greatest Happiness principle is a STANDARD, and not a FOUNDATION, and that its validity as a standard of right and wrong action is just as tenable by one who believes the moral sense to be innate, as by one who holds that it is acquired. He says distinctly that the social feelings of mankind form 'the natural basis of sentiment for utilitarian morality.' So far from holding the Greatest Happiness principle to be the foundation of morality, he would describe it as the forming principle of the superstructure of which the social feelings of mankind are the foundation. Between Mr. Darwin and utilitarians, as utilitarians, there is no such quarrel as he would appear to suppose. The narrowest utilitarian could say little more than Mr. Darwin says (ii. 393): 'As all men desire their own happiness, praise or blame is bestowed on actions and motives according as they tend to this end; and, as happiness is an essential part of the general good, the Greatest Happiness principle INDIRECTLY serves as a NEARLY safe standard of right and wrong.' It is perhaps not impertinent to suspect that the faltering adverbs which we have printed in italics indicate no more than the reluctance of a half-conscious convert to pure utilitarianism. In another place (i. 98) he admits that 'as all wish for happiness, the Greatest Happiness principle will have become a most important secondary guide and object, the social instincts, including sympathy, always serving as the primary impulse and guide.' This is just what Mr. Mill says, only instead of calling the principle a secondary guide, he would call it a standard, to distinguish it from the social impulse, in which, as much as Mr. Darwin, he recognises the base and foundation."--"Pall Mall Gazette," April 12th, 1871.) How the mistake which I have made in speaking of greatest happiness as the foundation of morals arose, is utterly unintelligible to me: any time during the last several years I should have laughed such an idea to scorn. Mr. Lecky never made a greater blunder, and your kindness has made you let me off too easily. (242/2. In the first edition of the "Descent of Man," I., page 97, Mr. Lecky is quoted as one of those who assumed that the "foundation of morality lay in a form of selfishness; but more recently in the 'greatest happiness' principle." Mr. Lecky's name is omitted in this connection in the second edition, page 120. In this edition Mr. Darwin makes it clearer that he attaches most importance to the social instinct as the "primary impulse and guide.") With respect to Mr. Mill, nothing would have pleased me more than to have relied on his great authority with respect to the social instincts, but the sentence which I quote at [Volume I.] page 71 ("if, as is my own belief, the moral feelings are not innate, but acquired, they are not for that reason less natural") seems to me somewhat contradictory with the other words which I quote, so that I did not know what to think; more especially as he says so very little about the social instincts. When I speak of intellectual activity as the secondary basis of conscience, I meant in my own mind secondary in period of development; but no one could be expected to understand so great an ellipse. With reference to your last sentence, do you not think that man might have retrograded in his parental, marriage, and other instincts without having retrograded in his social instincts? and I do not think that there is any evidence that man ever existed as a non-social animal. I must add that I have been very glad to read your remarks on the supposed case of the hive-bee: it affords an amusing contrast with what Miss Cobbe has written in the "Theological Review." (242/3. Mr. Darwin says ("Descent of Man" Edition I., Volume I., page 73; Edition II., page 99), "that if men lived like bees our unmarried females would think it a sacred duty to kill their brothers." Miss Cobbe remarks on this "that the principles of social duty would be reversed" ("Theological Review," April 1872). Mr. Morley, on the other hand, says of Darwin's assertion, that it is "as reassuring as the most absolute of moralists could desire. For it is tantamount to saying that the foundations of morality, the distinctions of right and wrong, are deeply laid in the very conditions of social existence; that there is in face of these conditions a positive and definite difference between the moral and the immoral, the virtuous and the vicious, the right and the wrong, in the actions of individuals partaking of that social existence.") Undoubtedly the great principle of acting for the good of all the members of the same community, and therefore the good of the species, would still have held sovereign sway. LETTER 243. TO J.D. HOOKER. (243/1. Sir Joseph Hooker wrote (August 5th, 1871) to Darwin about Lord Kelvin's Presidential Address at the Edinburgh meeting of the British Association: "It seems to me to be very able indeed; and what a good notion it gives of the gigantic achievement of mathematicians and physicists!--it really made one giddy to read of them. I do not think Huxley will thank him for his reference to him as a positive unbeliever in spontaneous generation--these mathematicians do not seem to me to distinguish between un-belief and a-belief. I know no other name for the state of mind that is produced under the term scepticism. I had no idea before that pure Mathematics had achieved such wonders in practical science. The total absence of any allusion to Tyndall's labours, even when comets are his theme, seems strange to me.") Haredene, Albury, Guildford, August 6th [1871]. I have read with greatest interest Thomson's address; but you say so EXACTLY AND FULLY all that I think, that you have taken all the words from my mouth; even about Tyndall. It is a gain that so wonderful a man, though no naturalist, should become a convert to evolution; Huxley, it seems, remarked in his speech to this effect. I should like to know what he means about design,--I cannot in the least understand, for I presume he does not believe in special interpositions. (243/2. See "British Association Report," page cv. Lord Kelvin speaks very doubtfully of evolution. After quoting the concluding passage of the "Origin," he goes on, "I have omitted two sentences...describing briefly the hypothesis of 'the origin of species by Natural Selection,' because I have always felt that this hypothesis does not contain the true theory of evolution, IF EVOLUTION THERE HAS BEEN in biology" (the italics are not in the original). Lord Kelvin then describes as a "most valuable and instructive criticism," Sir John Herschel's remark that the doctrine of Natural Selection is "too like the Laputan method of making books, and that it did not sufficiently take into account a continually guiding and controlling intelligence." But it should be remembered that it was in this address of Lord Kelvin's that he suggested the possibility of "seed-bearing meteoric stones moving about through space" inoculating the earth with living organisms; and if he assumes that the whole population of the globe is to be traced back to these "moss-grown fragments from the ruins of another world," it is obvious that he believes in a form of evolution, and one in which a controlling intelligence is not very obvious, at all events not in the initial and all-important stage.) Herschel's was a good sneer. It made me put in the simile about Raphael's Madonna, when describing in the "Descent of Man" the manner of formation of the wondrous ball-and-socket ornaments, and I will swear to the truth of this case. (243/3. See "Descent of Man," II., page 141. Darwin says that no one will attribute the shading of the "eyes" on the wings of the Argus pheasant to the "fortuitous concourse of atoms of colouring-matter." He goes on to say that the development of the ball-and-socket effect by means of Natural Selection seems at first as incredible as that "one of Raphael's Madonnas should have been formed by the selection of chance daubs of paint." The remark of Herschel's, quoted in "Life and Letters," II., page 241, that the "Origin" illustrates the "law of higgledy-piggledy," is probably a conversational variant of the Laputan comparison which gave rise to the passage in the "Descent of Man" (see Letter 130).) You know the oak-leaved variety of the common honeysuckle; I could not persuade a lady that this was not the result of the honeysuckle climbing up a young oak tree! Is this not like the Viola case? LETTER 244. TO JOHN LUBBOCK (LORD AVEBURY). Haredene, Albury, Guildford, August 12th [1871]. I hope the proof-sheets having been sent here will not inconvenience you. I have read them with infinite satisfaction, and the whole discussion strikes me as admirable. I have no books here, and wish much I could see a plate of Campodea. (244/1. "On the Origin of Insects." By Sir John Lubbock, Bart. "Journ. Linn. Soc. (Zoology)," Volume XI., 1873, pages 422-6. (Read November 2nd, 1871.) In the concluding paragraph the author writes, "If these views are correct the genus Campodea [a beetle] must be regarded as a form of remarkable interest, since it is the living representative of a primaeval type from which not only the Collembola and Thysanura, but the other great orders of insects, have all derived their origin." (See also "Brit. Assoc. Report," 1872, page 125--Address by Sir John Lubbock; and for a figure of Campodea see "Nature," Volume VII., 1873, page 447.) I never reflected much on the difficulty which you indicate, and on which you throw so much light. (244/2. The difficulty alluded to is explained by the first sentence of Lord Avebury's paper. "The Metamorphoses of this group (Insects) have always seemed to me one of the greatest difficulties of the Darwinian theory...I feel great difficulty in conceiving by what natural process an insect with a suctorial mouth, like that of a gnat or butterfly, could be developed from a powerfully mandibulate type like the orthoptera, or even from the neuroptera...A clue to the difficulty may, I think, be found in the distinction between the developmental and adaptive changes to which I called the attention of the Society in a previous memoir." The distinction between developmental and adaptive changes is mentioned, but not discussed, in the paper "On the Origin of Insects" (loc. cit., page 422); in a former paper, "On the Development of Chloeon (Ephemera) dimidiatum ("Trans. Linn. Soc." XXV. page 477, 1866), this question is dealt with at length.) I have only a few trifling remarks to make. At page 44 I wish you had enlarged a little on what you have said of the distinction between developmental and adaptive changes; for I cannot quite remember the point, and others will perhaps be in the same predicament. I think I always saw that the larva and the adult might be separately modified to any extent. Bearing in mind what strange changes of function parts undergo, with the intermediate state of use (244/3. This slightly obscure phrase may be paraphrased, "the gradational stages being of service to the organism."), it seems to me that you speak rather too boldly on the impossibility of a mandibulate insect being converted into a sucking insect (244/4. "There are, however, peculiar difficulties in those cases in which, as among the lepidoptera, the same species is mandibulate as a larva and suctorial as an embryo" (Lubbock, "Origin of Insects," page 423).); not that I in the least doubt the value of your explanation. Cirripedes passing through what I have called a pupal state (244/5. "Hence, the larva in this, its last stage, cannot eat; it may be called a "locomotive Pupa;" its whole organisation is apparently adapted for the one great end of finding a proper site for its attachment and final metamorphosis." ("A Monograph on the Sub-Class Cirripedia." By Charles Darwin. London, Ray Soc., 1851.)) so far as their mouths are concerned, rather supports what you say at page 52. At page 40 your remarks on the Argus pheasant (244/6. There is no mention of the Argus pheasant in the published paper.) (though I have not the least objection to them) do not seem to me very appropriate as being related to the mental faculties. If you can spare me these proof-sheets when done with, I shall be obliged, as I shall be correcting a new edition of the "Origin" when I return home, though this subject is too large for me to enter on. I thank you sincerely for the great interest which your discussion has given me. LETTER 245. TO J.D. HOOKER. (245/1. The following letter refers to Mivart's "Genesis of Species.") Down, September 16th [1871]. I am preparing a new and cheap edition of the "Origin," and shall introduce a new chapter on gradation, and on the uses of initial commencements of useful structures; for this, I observe, has produced the greatest effect on most persons. Every one of his [Mivart's] cases, as it seems to me, can be answered in a fairly satisfactory manner. He is very unfair, and never says what he must have known could be said on my side. He ignores the effect of use, and what I have said in all my later books and editions on the direct effects of the conditions of life and so-called spontaneous variation. I send you by this post a very clever, but ill-written review from N. America by a friend of Asa Gray, which I have republished. (245/2. Chauncey Wright in the "North American Review," Volume CXIII., reprinted by Darwin and published as a pamphlet (see "Life and Letters," III., page 145).) I am glad to hear about Huxley. You never read such strong letters Mivart wrote to me about respect towards me, begging that I would call on him, etc., etc.; yet in the "Q. Review" (245/3. See "Quarterly Review," July 1871; also "Life and Letters," III., page 147.) he shows the greatest scorn and animosity towards me, and with uncommon cleverness says all that is most disagreeable. He makes me the most arrogant, odious beast that ever lived. I cannot understand him; I suppose that accursed religious bigotry is at the root of it. Of course he is quite at liberty to scorn and hate me, but why take such trouble to express something more than friendship? It has mortified me a good deal. LETTER 246. TO J.D. HOOKER. Down, October 4th [1871]. I am quite delighted that you think so highly of Huxley's article. (246/1. A review of Wallace's "Natural Selection," of Mivart's "Genesis of Species," and of the "Quarterly Review" article on the "Descent of Man" (July, 1871), published in the "Contemporary Review" (1871), and in Huxley's "Collected Essays," II., page 120.) I was afraid of saying all I thought about it, as nothing is so likely as to make anything appear flat. I thought of, and quite agreed with, your former saying that Huxley makes one feel quite infantile in intellect. He always thus acts on me. I exactly agree with what you say on the several points in the article, and I piled climax on climax of admiration in my letter to him. I am not so good a Christian as you think me, for I did enjoy my revenge on Mivart. He (i.e. Mivart) has just written to me as cool as a cucumber, hoping my health is better, etc. My head, by the way, plagues me terribly, and I have it light and rocking half the day. Farewell, dear old friend--my best of friends. LETTER 247. TO JOHN FISKE. (247/1. Mr. Fiske, who is perhaps best known in England as the author of "Outlines of Cosmic Philosophy," had sent to Mr. Darwin some reports of the lectures given at Harvard University. The point referred to in the postscript in Mr. Darwin's letter is explained by the following extract from Mr. Fiske's work: "I have endeavoured to show that the transition from animality (or bestiality, stripping the word of its bad connotations) to humanity must have been mainly determined by the prolongation of infancy or immaturity which is consequent upon a high development of intelligence, and which must have necessitated the gradual grouping together of pithecoid men into more or less definite families." (See "Descent," I., page 13, on the prolonged infancy of the anthropoid apes.)) Down, November 9th, 1871. I am greatly obliged to you for having sent me, through my son, your lectures, and for the very honourable manner in which you allude to my works. The lectures seem to me to be written with much force, clearness, and originality. You show also a truly extraordinary amount of knowledge of all that has been published on the subject. The type in many parts is so small that, except to young eyes, it is very difficult to read. Therefore I wish that you would reflect on their separate publication, though so much has been published on the subject that the public may possibly have had enough. I hope that this may be your intention, for I do not think I have ever seen the general argument more forcibly put so as to convert unbelievers. It has surprised and pleased me to see that you and others have detected the falseness of much of Mr. Mivart's reasoning. I wish I had read your lectures a month or two ago, as I have been preparing a new edition of the "Origin," in which I answer some special points, and I believe I should have found your lectures useful; but my MS. is now in the printer's hands, and I have not strength or time to make any more additions. P.S.--By an odd coincidence, since the above was written I have received your very obliging letter of October 23rd. I did notice the point to which you refer, and will hereafter reflect more over it. I was indeed on the point of putting in a sentence to somewhat of the same effect in the new edition of the "Origin," in relation to the query--Why have not apes advanced in intellect as much as man? but I omitted it on account of the asserted prolonged infancy of the orang. I am also a little doubtful about the distinction between gregariousness and sociability. ...When you come to England I shall have much pleasure in making your acquaintance; but my health is habitually so weak that I have very small power of conversing with my friends as much as I wish. Let me again thank you for your letter. To believe that I have at all influenced the minds of able men is the greatest satisfaction I am capable of receiving. LETTER 248. TO E. HACKEL. Down, December 27th, 1871. I thank you for your very interesting letter, which it has given me much pleasure to receive. I never heard of anything so odd as the Prior in the Holy Catholic Church believing in our ape-like progenitors. I much hope that the Jesuits will not dislodge him. What a wonderfully active man you are! and I rejoice that you have been so successful in your work on sponges. (248/1. "Die Kalkschwamme: eine Monographie; 3 volumes: Berlin, 1872. H.J. Clark published a paper "On the Spongiae Ciliatae as Infusoria flagellata" in the "Mem. Boston Nat. Hist. Soc." Volume I., Part iii., 1866. See Hackel, op. cit., Volume I., page 24.) Your book with sixty plates will be magnificent. I shall be glad to learn what you think of Clark's view of sponges being flagellate infusorians; some observers in this country believe in him. I am glad you are going fully to consider inheritance, which is an all-important subject for us. I do not know whether you have ever read my chapter on pangenesis. My ideas have been almost universally despised, and I suppose that I was foolish to publish them; yet I must still think that there is some truth in them. Anyhow, they have aided me much in making me clearly understand the facts of inheritance. I have had bad health this last summer, and during two months was able to do nothing; but I have now almost finished a next edition of the "Origin," which Victor Carus is translating. (248/2. See "Life and Letters," III., page 49.) There is not much new in it, except one chapter in which I have answered, I hope satisfactorily, Mr. Mivart's supposed difficulty on the incipient development of useful structures. I have also given my reasons for quite disbelieving in great and sudden modifications. I am preparing an essay on expression in man and the lower animals. It has little importance, but has interested me. I doubt whether my strength will last for much more serious work. I hope, however, to publish next summer the results of my long-continued experiments on the wonderful advantages derived from crossing. I shall continue to work as long as I can, but it does not much signify when I stop, as there are so many good men fully as capable, perhaps more capable, than myself of carrying on our work; and of these you rank as the first. With cordial good wishes for your success in all your work and for your happiness. LETTER 249. TO E. RAY LANKESTER. Down, April 15th [1872]. Very many thanks for your kind consideration. The correspondence was in the "Athenaeum." I got some mathematician to make the calculation, and he blundered and caused me much shame. I send scrap of proofs from last edition of the "Origin," with the calculation corrected. What grand work you did at Naples! I can clearly see that you will some day become our first star in Natural History. (249/1. Here follows the extract from the "Origin," sixth edition, page 51: "The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase. It will be safest to assume that it begins breeding when thirty years old, and goes on breeding till ninety years old, bringing forth six young in the interval, and surviving till one hundred years old; if this be so, after a period of from 740 to 750 years, there would be nearly nineteen million elephants alive, descended from the first pair." In the fifth edition, page 75, the passage runs: "If this be so, at the end of the fifth century, there would be alive fifteen million elephants, descended from the first pair" (see "Athenaeum," June 5, July 3, 17, 24, 1869).) LETTER 250. TO C. LYELL. Down, May 10th [1872]. I received yesterday morning your present of that work to which I, for one, as well as so many others, owe a debt of gratitude never to be forgotten. I have read with the greatest interest all the special additions; and I wish with all my heart that I had the strength and time to read again every word of the whole book. (250/1. "Principles of Geology," Edition XII., 1875.) I do not agree with all your criticisms on Natural Selection, nor do I suppose that you would expect me to do so. We must be content to differ on several points. I differ must about your difficulty (page 496) (250/2. In Chapter XLIII. Lyell treats of "Man considered with reference to his Origin and Geographical Distribution." He criticizes the view that Natural Selection is capable of bringing about any amount of change provided a series of minute transitional steps can be pointed out. "But in reality," he writes, "it cannot be said that we obtain any insight into the nature of the forces by which a higher grade of organisation or instinct is evolved out of a lower one by becoming acquainted with a series of gradational forms or states, each having a very close affinity with the other."..."It is when there is a change from an inferior being to one of superior grade, from a humbler organism to one endowed with new and more exalted attributes, that we are made to feel that, to explain the difficulty, we must obtain some knowledge of those laws of variation of which Mr. Darwin grants that we are at present profoundly ignorant" (op. cit., pages 496-97).) on a higher grade of organisation being evolved out of lower ones. Is not a very clever man a grade above a very dull one? and would not the accumulation of a large number of slight differences of this kind lead to a great difference in the grade of organisation? And I suppose that you will admit that the difference in the brain of a clever and dull man is not much more wonderful than the difference in the length of the nose of any two men. Of course, there remains the impossibility of explaining at present why one man has a longer nose than another. But it is foolish of me to trouble you with these remarks, which have probably often passed through your mind. The end of this chapter (XLIII.) strikes me as admirably and grandly written. I wish you joy at having completed your gigantic undertaking, and remain, my dear Lyell, Your ever faithful and now very old pupil, CHARLES DARWIN. LETTER 251. TO J. TRAHERNE MOGGRIDGE. Sevenoaks, October 9th [1872]. I have just received your note, forwarded to me from my home. I thank you very truly for your intended present, and I am sure that your book will interest me greatly. I am delighted that you have taken up the very difficult and most interesting subject of the habits of insects, on which Englishmen have done so little. How incomparably more valuable are such researches than the mere description of a thousand species! I daresay you have thought of experimenting on the mental powers of the spiders by fixing their trap-doors open in different ways and at different angles, and observing what they will do. We have been here some days, and intend staying some weeks; for I was quite worn out with work, and cannot be idle at home. I sincerely hope that your health is not worse. LETTER 252. TO A. HYATT. (252/1. The correspondence with Professor Hyatt, of Boston, U.S., originated in the reference to his and Professor Cope's theories of acceleration and retardation, inserted in the sixth edition of the "Origin," page 149. Mr. Darwin, on receiving from Mr. Hyatt a copy of his "Fossil Cephalopods of the Museum of Comparative Zoology. Embryology," from the "Bull. Mus. Comp. Zool." Harvard, Volume III., 1872, wrote as follows (252/2. Part of this letter was published in "Life and Letters," III., page 154.):--) October 10th, 1872. I am very much obliged to you for your kindness in having sent me your valuable memoir on the embryology of the extinct cephalopods. The work must have been one of immense labour, and the results are extremely interesting. Permit me to take this opportunity to express my sincere regret at having committed two grave errors in the last edition of my "Origin of Species," in my allusion to yours and Professor Cope's views on acceleration and retardation of development. I had thought that Professor Cope had preceded you; but I now well remember having formerly read with lively interest, and marked, a paper by you somewhere in my library, on fossil cephalopods, with remarks on the subject. (252/3. The paper seems to be "On the Parallelism between the Different Stages of Life in the Individual and those in the Entire Group of the Molluscous Order Tetrabranchiata," from the "Boston. Soc. Nat. Hist. Mem." I., 1866-69, page 193. On the back of the paper is written, "I cannot avoid thinking this paper fanciful.") It seems also that I have quite misrepresented your joint view; this has vexed me much. I confess that I have never been able to grasp fully what you wish to show, and I presume that this must be owing to some dulness on my part...As the case stands, the law of acceleration and retardation seems to me to be a simple [?] statement of facts; but the statement, if fully established, would no doubt be an important step in our knowledge. But I had better say nothing more on the subject, otherwise I shall perhaps blunder again. I assure you that I regret much that I have fallen into two such grave errors. LETTER 253. A. HYATT TO CHARLES DARWIN. (253/1. Mr. Hyatt replied in a long letter, of which only a small part is here given. Cannstadt bei Stuttgart, November 1872. The letter with which you have honoured me, bearing the date of October 10th, has just reached here after a voyage to America and back. I have long had it in mind to write you upon the subject of which you speak, but have been prevented by a very natural feeling of distrust in the worthiness and truth of the views which I had to present. There is certainly no occasion to apologise for not having quoted my paper. The law of acceleration and retardation of development was therein used to explain the appearance of other phenomena, and might, as it did in nearly all cases, easily escape notice. My relations with Prof. Cope are of the most friendly character; and although fortunate in publishing a few months ahead, I consider that this gives me no right to claim anything beyond such an amount of participation in the discovery, if it may be so called, as the thoroughness and worth of my work entitles me to... The collections which I have studied, it will be remembered, are fossils collected without special reference to the very minute subdivisions, such as the subdivisions of the Lower or Middle Lias as made by the German authors, especially Quenstedt and Oppel, but pretty well defined for the larger divisions in which the species are also well defined. The condition of the collections as regards names, etc., was chaotic, localities alone, with some few exceptions, accurate. To put this in order they were first arranged according to their adult characteristics. This proving unsatisfactory, I determined to test thoroughly the theory of evolution by following out the developmental history of each species and placing them within their formations, Middle or Upper Lias, Oolite or so, according to the extent to which they represented each other's characteristics. Thus an adult of simple structure being taken as the starting-point which we will call a, another species which was a in its young stage and became b in the adult was placed above it in the zoological series. By this process I presently found that a, then a b and a b c, c representing the adult stage, were very often found; but that practically after passing these two or three stages it did not often happen that a species was found which was a b c in the young and then became d in the adult. But on the other hand I very frequently found one which, while it was a in the young, skipped the stages b and c and became d while still quite young. Then sometimes, though more rarely, a species would be found belonging to the same series, which would be a in the young and with a very faint and fleeting resemblance to d at a later stage, pass immediately while still quite young to the more advanced characteristics represented by e, and hold these as its specific characteristics until old age destroyed them. This skipping is the highest exemplification, or rather manifestation, of acceleration in development. In alluding to the history of diseases and inheritance of characteristics, you in your "Origin of Species" allude to the ordinary manifestation of acceleration, when you speak of the tendency of diseases or characteristics to appear at younger periods in the life of the child than of its parents. This, according to my observations, is a law, or rather mode, of development, which is applicable to all characteristics, and in this way it is possible to explain why the young of later-occurring animals are like the adult stages of those which preceded them in time. If I am not mistaken you have intimated something of this sort also in your first edition, but I have not been able to find it lately. Of course this is a very normal condition of affairs when a series can be followed in this way, beginning with species a, then going through species a b to a b c, then a b d or a c d, and then a d e or simply a e, as it sometimes comes. Very often the acceleration takes place in two closely connected series, thus: a--ab--abd--ae---ad in which one series goes on very regularly, while another lateral offshoot of a becomes d in the adult. This is an actual case which can be plainly shown with the specimens in hand, and has been verified in the collections here. Retardation is entirely Prof. Cope's idea, but I think also easily traceable. It is the opponent of acceleration, so to speak, or the opposite or negative of that mode of development. Thus series may occur in which, either in size or characteristics, they return to former characteristics; but a better discussion of this point you will find in the little treatise which I send by the same mail as this letter, "On Reversions among the Ammonites." LETTER 254. TO A. HYATT. Down, December 4th, 1872. I thank you sincerely for your most interesting letter. You refer much too modestly to your own knowledge and judgment, as you are much better fitted to throw light on your own difficult problems than I am. It has quite annoyed me that I do not clearly understand yours and Prof. Cope's views (254/1. Prof. Cope's views may be gathered from his "Origin of the Fittest" 1887; in this book (page 41) is reprinted his "Origin of Genera" from the "Proc. Philadelph. Acad. Nat. Soc." 1868, which was published separately by the author in 1869, and which we believe to be his first publication on the subject. In the preface to the "Origin of the Fittest," page vi, he sums up the chief points in the "Origin of Genera" under seven heads, of which the following are the most important:--"First, that development of new characters has been accomplished by an ACCELERATION or RETARDATION in the growth of the parts changed...Second, that of EXACT PARALLELISM between the adult of one individual or set of individuals, and a transitional stage of one or more other individuals. This doctrine is distinct from that of an exact parallelism, which had already been stated by von Baer." The last point is less definitely stated by Hyatt in his letter of December 4th, 1872. "I am thus perpetually led to look upon a series very much as upon an individual, and think that I have found that in many instances these afford parallel changes." See also "Lamarck the Founder of Evolution, by A.S. Packard: New York, 1901.) and the fault lies in some slight degree, I think, with Prof. Cope, who does not write very clearly. I think I now understand the terms "acceleration" and "retardation"; but will you grudge the trouble of telling me, by the aid of the following illustration, whether I do understand rightly? When a fresh-water decapod crustacean is born with an almost mature structure, and therefore does not pass, like other decapods, through the Zoea stage, is this not a case of acceleration? Again, if an imaginary decapod retained, when adult, many Zoea characters, would this not be a case of retardation? If these illustrations are correct, I can perceive why I have been so dull in understanding your views. I looked for something else, being familiar with such cases, and classing them in my own mind as simply due to the obliteration of certain larval or embryonic stages. This obliteration I imagined resulted sometimes entirely from that law of inheritance to which you allude; but that it in many cases was aided by Natural Selection, as I inferred from such cases occurring so frequently in terrestrial and fresh-water members of groups, which retain their several embryonic stages in the sea, as long as fitting conditions are present. Another cause of my misunderstanding was the assumption that in your series a--ab--abd--ae,--------ad the differences between the successive species, expressed by the terminal letter, was due to acceleration: now, if I understand rightly, this is not the case; and such characters must have been independently acquired by some means. The two newest and most interesting points in your letter (and in, as far as I think, your former paper) seem to me to be about senile characteristics in one species appearing in succeeding species during maturity; and secondly about certain degraded characters appearing in the last species of a series. You ask for my opinion: I can only send the conjectured impressions which have occurred to me and which are not worth writing. (It ought to be known whether the senile character appears before or after the period of active reproduction.) I should be inclined to attribute the character in both your cases to the laws of growth and descent, secondarily to Natural Selection. It has been an error on my part, and a misfortune to me, that I did not largely discuss what I mean by laws of growth at an early period in some of my books. I have said something on this head in two new chapters in the last edition of the "Origin." I should be happy to send you a copy of this edition, if you do not possess it and care to have it. A man in extreme old age differs much from a young man, and I presume every one would account for this by failing powers of growth. On the other hand the skulls of some mammals go on altering during maturity into advancing years; as do the horns of the stag, the tail-feathers of some birds, the size of fishes etc.; and all such differences I should attribute simply to the laws of growth, as long as full vigour was retained. Endless other changes of structure in successive species may, I believe, be accounted for by various complex laws of growth. Now, any change of character thus induced with advancing years in the individual might easily be inherited at an earlier age than that at which it first supervened, and thus become characteristic of the mature species; or again, such changes would be apt to follow from variation, independently of inheritance, under proper conditions. Therefore I should expect that characters of this kind would often appear in later-formed species without the aid of Natural Selection, or with its aid if the characters were of any advantage. The longer I live, the more I become convinced how ignorant we are of the extent to which all sorts of structures are serviceable to each species. But that characters supervening during maturity in one species should appear so regularly, as you state to be the case, in succeeding species, seems to me very surprising and inexplicable. With respect to degradation in species towards the close of a series, I have nothing to say, except that before I arrived at the end of your letter, it occurred to me that the earlier and simpler ammonites must have been well adapted to their conditions, and that when the species were verging towards extinction (owing probably to the presence of some more successful competitors) they would naturally become re-adapted to simpler conditions. Before I had read your final remarks I thought also that unfavourable conditions might cause, through the law of growth, aided perhaps by reversion, degradation of character. No doubt many new laws remain to be discovered. Permit me to add that I have never been so foolish as to imagine that I have succeeded in doing more than to lay down some of the broad outlines of the origin of species. After long reflection I cannot avoid the conviction that no innate tendency to progressive development exists, as is now held by so many able naturalists, and perhaps by yourself. It is curious how seldom writers define what they mean by progressive development; but this is a point which I have briefly discussed in the "Origin." I earnestly hope that you may visit Hilgendorf's famous deposit. Have you seen Weismann's pamphlet "Einfluss der Isolirung," Leipzig, 1872? He makes splendid use of Hilgendorf's admirable observations. (254/2. Hilgendorf, "Monatsb. K. Akad." Berlin, 1866. For a semi-popular account of Hilgendorf's and Hyatt's work on this subject, see Romanes' "Darwin and after Darwin," I., page 201.) I have no strength to spare, being much out of health; otherwise I would have endeavoured to have made this letter better worth sending. I most sincerely wish you success in your valuable and difficult researches. I have received, and thank you, for your three pamphlets. As far as I can judge, your views seem very probable; but what a fearfully intricate subject is this of the succession of ammonites. (254/3. See various papers in the publications of the "Boston Soc. Nat. Hist." and in the "Bulletin of the Harvard Museum of Comp. Zoology.") LETTER 255. A. HYATT TO CHARLES DARWIN. Cannstadt bei Stuttgart, December 8th, 1872. The quickness and earnestness of your reply to my letter gives me the greatest encouragement, and I am much delighted at the unexpected interest which your questions and comments display. What you say about Prof. Cope's style has been often before said to me, and I have remarked in his writings an unsatisfactory treatment of our common theory. This, I think, perhaps is largely due to the complete absorption of his mind in the contemplation of his subject: this seems to lead him to be careless about the methods in which it may be best explained. He has, however, a more extended knowledge than I have, and has in many ways a more powerful grasp of the subject, and for that very reason, perhaps, is liable to run into extremes. You ask about the skipping of the Zoea stage in fresh-water decapods: is this an illustration of acceleration? It most assuredly is, if acceleration means anything at all. Again, another and more general illustration would be, if, among the marine decapods, a series could be formed in which the Zoea stage became less and less important in the development, and was relegated to younger and younger stages of the development, and finally disappeared in those to which you refer. This is the usual way in which the accelerated mode of development manifests itself; though near the lowest or earliest occurring species it is also to be looked for. Perhaps this to which you allude is an illustration somewhat similar to the one which I have spoken of in my series, a--ab--abc--ae--------ad, which like "a d" comes from the earliest of a series, though I should think from the entire skipping of the Zoea stage that it must be, like "a e," the result of a long line of ancestors. In fact, the essential point of our theory is, that characteristics are ever inherited by the young at earlier periods than they are assumed in due course of growth by the parents, and that this must eventually lead to the extinction or skipping of these characteristics altogether... Such considerations as these and the fact that near the heads of series or near the latest members of series, and not at the beginning, were usually found the accelerated types, which skipped lower characteristics and developed very suddenly to a higher and more complex standpoint in structure, led both Cope and [myself] into what may be a great error. I see that it has led you at least into the difficulty of which you very rightly complain, and which, I am sorry to see, has cost you some of your valuable time. We presumed that because characteristics were perpetually inherited at earlier stages, that this very concentration of the developed characteristics made room for the production of differences in the adult descendants of any given pair. Further, that in the room thus made other different characteristics must be produced, and that these would necessarily appear earlier in proportion as the species was more or less accelerated, and be greater or less in the same proportion. Finally, that in the most accelerated, such as "a c" or "a d," the difference would be so great as to constitute distinct genera. Cope and I have differed very much, while he acknowledged the action of the accumulated mode of development only when generic characteristics or greater differences were produced, I saw the same mode of development to be applicable in all cases and to all characteristics, even to diseases. So far the facts bore us out, but when we assumed that the adult differences were the result of the accelerated mode of development, we were perhaps upon rather insecure ground. It is evidently this assumption which has led you to misunderstand the theory. Cope founded his belief, that the adult characteristics were also the result of acceleration, if I rightly remember it, mainly upon the class of facts spoken of above in man where a sudden change into two organs may produce entirely new and unexpected differences in the whole organisation, and upon the changes which acceleration appeared to produce in the development of each succeeding species. Your difficulty in understanding the theory and the observations you have made show me at once what my own difficulties have been, but of these I will not speak at present, as my letter is spinning itself out to a fearful length. (255/1. After speaking of Cope's comparison of acceleration and retardation in evolution to the force of gravity in physical matters Mr. Hyatt goes on:--) Now it [acceleration] seems to me to explain less and less the origin of adult progressive characteristics or simply differences, and perhaps now I shall get on faster with my work. LETTER 256. TO A. HYATT. Down, December 14th [1872]. (256/1. In reply to the above letter (255) from Mr. Hyatt.) Notwithstanding the kind consideration shown in your last sentence, I must thank you for your interesting and clearly expressed letter. I have directed my publisher to send you a copy of the last edition of the "Origin," and you can, if you like, paste in the "From the Author" on next page. In relation to yours and Professor Cope's view on "acceleration" causing a development of new characters, it would, I think, be well if you were to compare the decapods which pass and do not pass through the Zoea stage, and the one group which does (according to Fritz Muller) pass through to the still earlier Nauplius stages, and see if they present any marked differences. You will, I believe, find that this is not the case. I wish it were, for I have often been perplexed at the omission of embryonic stages as well as the acquirement of peculiar stages appearing to produce no special result in the mature form. (256/2. The remainder of this letter is missing, and the whole of the last sentence is somewhat uncertainly deciphered. (Note by Mr. Hyatt.)) LETTER 257. TO A. HYATT. Down, February 13th, 1877. I thank you for your very kind, long, and interesting letter. The case is so wonderful and difficult that I dare not express any opinion on it. Of course, I regret that Hilgendorf has been proved to be so greatly in error (257/1. This refers to a controversy with Sandberger, who had attacked Hilgendorf in the "Verh. der phys.-med. Ges. zu Wurzburg," Bd. V., and in the "Jahrb. der Malakol. Ges." Bd. I., to which Hilgendorf replied in the "Zeitschr. d. Deutschen geolog. Ges." Jahrb. 1877. Hyatt's name occurs in Hilgendorf's pages, but we find no reference to any paper of this date; his well-known paper is in the "Boston. Soc. Nat. Hist." 1880. In a letter to Darwin (May 23rd, 1881) Hyatt regrets that he had no opportunity of a third visit to Steinheim, and goes on: "I should then have done greater justice to Hilgendorf, for whom I have such a high respect."), but it is some selfish comfort to me that I always felt so much misgiving that I never quoted his paper. (257/2. In the fifth edition of the "Origin" (page 362), however, Darwin speaks of the graduated forms of Planorbis multiformis, described by Hilgendorf from certain beds in Switzerland, by which we presume he meant the Steinheim beds in Wurtemberg.) The variability of these shells is quite astonishing, and seems to exceed that of Rubus or Hieracium amongst plants. The result which surprises me most is that the same form should be developed from various and different progenitors. This seems to show how potent are the conditions of life, irrespectively of the variations being in any way beneficial. The production of a species out of a chaos of varying forms reminds me of Nageli's conclusion, as deduced from the study of Hieracium, that this is the common mode in which species arise. But I still continue to doubt much on this head, and cling to the belief expressed in the first edition of the "Origin," that protean or polymorphic species are those which are now varying in such a manner that the variations are neither advantageous nor disadvantageous. I am glad to hear of the Brunswick deposit, as I feel sure that the careful study of such cases is highly important. I hope that the Smithsonian Institution will publish your memoir. LETTER 258. TO A. DE CANDOLLE. Down, January 18th [1873]. It was very good of you to give up so much of your time to write to me your last interesting letter. The evidence seems good about the tameness of the alpine butterflies, and the fact seems to me very surprising, for each butterfly can hardly have acquired its experience during its own short life. Will you be so good as to thank M. Humbert for his note, which I have been glad to read. I formerly received from a man, not a naturalist, staying at Cannes a similar account, but doubted about believing it. The case, however, does not answer my query--viz., whether butterflies are attracted by bright colours, independently of the supposed presence of nectar? I must own that I have great difficulty in believing that any temporary condition of the parents can affect the offspring. If it last long enough to affect the health or structure of the parents, I can quite believe the offspring would be modified. But how mysterious a subject is that of generation! Although my hypothesis of pangenesis has been reviled on all sides, yet I must still look at generation under this point of view; and it makes me very averse to believe in an emotion having any effect on the offspring. Allow me to add one word about blushing and shyness: I intended only to say the habit was primordially acquired by attention to the face, and not that each shy man now attended to his personal appearance. LETTER 259. TO J.D. HOOKER. Down, June 28th, 1873. I write a line to wish you good-bye, as I hear you are off on Wednesday, and to thank you for the Dionoea, but I cannot make the little creature grow well. I have this day read Bentham's last address, and must express my admiration of it. (259/1. Presidential address to the Linnean Society, read May 24th, 1873.) Perhaps I ought not to do so, as he fairly crushes me with honour. I am delighted to see how exactly I agree with him on affinities, and especially on extinct forms as illustrated by his flat-topped tree. (259/2. See page 15 of separate copy: "We should then have the present races represented by the countless branchlets forming the flat-topped summit" of a genealogical tree, in which "all we can do is to map out the summit as it were from a bird's-eye view, and under each cluster, or cluster of clusters, to place as the common trunk an imaginary type of a genus, order, or class according to the depth to which we would go.") My recent work leads me to differ from him on one point--viz., on the separation of the sexes. (259/3. On the question of sexuality, see page 10 of Bentham's address. On the back of Mr. Darwin's copy he has written: "As long as lowest organisms free--sexes separated: as soon as they become attached, to prevent sterility sexes united--reseparated as means of fertilisation, adapted [?] for distant [?] organisms,--in the case of animals by their senses and voluntary movements,--with plants the aid of insects and wind, the latter always existed, and long retained." The two words marked [?] are doubtful. The introduction of freedom or attachedness, as a factor in the problem also occurs in "Cross and Self-fertilisation," page 462. I strongly suspect that sexes were primordially in distinct individuals; then became commonly united in the same individual, and then in a host of animals and some few plants became again separated. Do ask Bentham to send a copy of his address to "Dr. H. Muller, Lippstadt, Prussia," as I am sure it will please him GREATLY. ...When in France write me a line and tell me how you get on, and how Huxley is; but do not do so if you feel idle, and writing bothers you. LETTER 260. TO R. MELDOLA. (260/1. This letter, with others from Darwin to Meldola, is published in "Charles Darwin and the Theory of Natural Selection," by E.B. Poulton, pages 199 et seq., London, 1896.) Southampton, August 13th, 1873. I am much obliged for your present, which no doubt I shall find at Down on my return home. I am sorry to say that I cannot answer your question; nor do I believe that you could find it anywhere even approximately answered. It is very difficult or impossible to define what is meant by a large variation. Such graduate into monstrosities or generally injurious variations. I do not myself believe that these are often or ever taken advantage of under nature. It is a common occurrence that abrupt and considerable variations are transmitted in an unaltered state, or not at all transmitted, to the offspring, or to some of them. So it is with tailless or hornless animals, and with sudden and great changes of colour in flowers. I wish I could have given you any answer. LETTER 261. TO E.S. MORSE. [Undated.] I must have the pleasure of thanking you for your kindness in sending me your essay on the Brachiopoda. (261/1. "The Brachiopoda, a Division of Annelida," "Amer. Assoc. Proc." Volume XIX., page 272, 1870, and "Annals and Mag. Nat. Hist." Volume VI., page 267, 1870.) I have just read it with the greatest interest, and you seem to me (though I am not a competent judge) to make out with remarkable clearness an extremely strong case. What a wonderful change it is to an old naturalist to have to look at these "shells" as "worms"; but, as you truly say, as far as external appearance is concerned, the case is not more wonderful than that of cirripedes. I have also been particularly interested by your remarks on the Geological Record, and on the lower and older forms in each great class not having been probably protected by calcareous valves or a shell. P.S.--Your woodcut of Lingula is most skilfully introduced to compel one to see its likeness to an annelid. LETTER 262. TO H. SPENCER. (262/1. Mr. Spencer's book "The Study of Sociology," 1873, was published in the "Contemporary Review" in instalments between May 1872 and October 1873.) October 31st [1873]. I am glad to receive to-day an advertisement of your book. I have been wonderfully interested by the articles in the "Contemporary." Those were splendid hits about the Prince of Wales and Gladstone. (262/2. See "The Study of Sociology," page 392. Mr. Gladstone, in protest against some words of Mr. Spencer, had said that the appearance of great men "in great crises of human history" were events so striking "that men would be liable to term them providential in a pre-scientific age." On this Mr. Spencer remarks that "in common with the ancient Greek Mr. Gladstone regards as irreligious any explanation of Nature which dispenses with immediate Divine superintendence." And as an instance of the partnership "between the ideas of natural causation and of providential interference," he instances a case where a prince "gained popularity by outliving certain abnormal changes in his blood," and where "on the occasion of his recovery providential aid and natural causation were unitedly recognised by a thanksgiving to God and a baronetcy to the doctor." The passage on Toryism is on page 395, where Mr. Spencer, with his accustomed tolerance, writes: "The desirable thing is that a growth of ideas and feelings tending to produce modification shall be joined with a continuance of ideas and feelings tending to preserve stability." And from this point of view he concludes it to be very desirable that "one in Mr. Gladstone's position should think as he does." The matter is further discussed in the notes to Chapter XVI., page 423.) I never before read a good defence of Toryism. In one place (but I cannot for the life of me recollect where or what it exactly was) I thought that you would have profited by my principle (i.e. if you do not reject it) given in my "Descent of Man," that new characters which appear late in life are those which are transmitted to the same sex alone. I have advanced some pretty strong evidence, and the principle is of great importance in relation to secondary sexual likenesses. (262/3. This refers to Mr. Spencer's discussion of the evolution of the mental traits characteristic of women. At page 377 he points out the importance of the limitation of heredity by sex in this relation. A striking generalisation on this question is given in the "Descent of Man," Edition I., Volume II., page 285: that when the adult male differs from the adult female, he differs in the same way from the young of both sexes. Can this law be applied in the case in which the adult female possesses characters not possessed by the male: for instance, the high degree of intuitive power of reading the mental states of others and of concealing her own--characters which Mr. Spencer shows to be accounted for by the relations between the husband and wife in a state of savagery. If so, the man should resemble "the young of both sexes" in the absence of these special qualities. This seems to be the case with some masculine characteristics, and childishness of man is not without recognition among women: for instance, by Dolly Winthrop in "Silas Marner," who is content with bread for herself, but bakes cake for children and men, whose "stomichs are made so comical, they want a change--they do, I know, God help 'em.") I have applied it to man and woman, and possibly it was here that I thought that you would have profited by the doctrine. I fear that this note will be almost illegible, but I am very tired. LETTER 263. G.J. ROMANES TO CHARLES DARWIN. (263/1. This is, we believe, the first letter addressed by the late Mr. Romanes to Mr. Darwin. It was put away with another on the same subject, and inscribed "Romanes on Abortion, with my answer (very important)." Mr. Darwin's answer given below is printed from his rough draft, which is in places barely decipherable. On the subject of these letters consult Romanes, "Darwin and after Darwin," Volume II., page 99, 1895.) Dunskaith, Parkhill, Ross-shire, July 10th, 1874. Knowing that you do not dissuade the more attentive of your readers from communicating directly to yourself any ideas they may have upon subjects connected with your writings, I take the liberty of sending the enclosed copy of a letter, which I have recently addressed to Mr. Herbert Spencer. You will perceive that the subject dealt with is the same as that to which a letter of mine in last week's "Nature" [July 2nd, page 164] refers--viz., "Disuse as a Reducing Cause in Species." In submitting this more detailed exposition of my views to your consideration, I should like to state again what I stated in "Nature" some weeks ago, viz., that in propounding the cessation of selection as a reducing cause, I do not suppose that I am suggesting anything which has not occurred to you already. Not only is this principle embodied in the theory set forth in the article on Rudimentary Organs ("Nature," Volume IX.); but it is more than once hinted at in the "Origin," in the passages where rudimentary organs are said to be more variable than others, because no longer under the restraining influence of Natural Selection. And still more distinctly is this principle recognised in page 120. Thus, in sending you the enclosed letter, I do not imagine that I am bringing any novel suggestions under your notice. As I see that you have already applied the principle in question to the case of artificially-bred structures, I cannot but infer that you have pondered it in connection with naturally-bred structures. What objection, however, you can have seen to this principle in this latter connection, I am unable to divine; and so I think the best course for me to pursue is the one I adopt--viz., to send you my considerations in full. In the absence of express information, the most natural inference is that the reason you refuse to entertain the principle in question, is because you show the backward tendency of indiscriminate variability [to be] inadequate to contend with the conservative tendency of long inheritance. The converse of this is expressed in the words "That the struggle between Natural Selection on the one hand, and the tendency to reversion and variability on the other hand, will in the course of time cease; and that the most abnormally developed organs may be made constant, I see no reason to doubt" ("Origin," page 121). Certainly not, if, as I doubt not, the word "constant" is intended to bear a relative signification; but to say that constancy can ever become absolute--i.e., that any term of inheritance could secure to an organ a total immunity from the smallest amount of spontaneous variability--to say this would be unwarrantable. Suppose, for instance, that for some reason or other a further increase in the size of a bat's wing should now suddenly become highly beneficial to that animal: we can scarcely suppose that variations would not be forthcoming for Natural Selection to seize upon (unless the limit of possible size has now been reached, which is an altogether distinct matter). And if we suppose that minute variations on the side of increase are thus even now occasionally taking place, much more is it probable that similar variations on the side of decrease are now taking place--i.e., that if the conservative influence of Natural Selection were removed for a long period of time, more variations would ensue below the present size of bat's wings, than above it. To this it may be added, that when the influence of "speedy selection" is removed, it seems in itself highly probable that the structure would, for this reason, become more variable, for the only reason why it ever ceased to be variable (i.e., after attaining its maximum size), was because of the influence of selection constantly destroying those individuals in which a tendency to vary occurred. When, therefore, this force antagonistic to variability was removed, it seems highly probable that the latter principle would again begin to assert itself, and this in a cumulative manner. Those individuals in which a tendency to vary occurred being no longer cut off, they would have as good a chance of leaving progeny to inherit their fluctuating disposition as would their more inflexible companions. LETTER 264. TO G.J. ROMANES. July 16th, 1874. I am much obliged for your kind and long communication, which I have read with great interest, as well as your articles in "Nature." The subject seems to me as important and interesting as it is difficult. I am much out of health, and working very hard on a very different subject, so thus I cannot give your remarks the attention which they deserve. I will, however, keep your letter for some later time, when I may again take up the subject. Your letter makes it clearer to me than it ever was before, how a part or organ which has already begun from any cause to decrease, will go on decreasing through so-called spontaneous variability, with intercrossing; for under such circumstances it is very unlikely that there should be variation in the direction of increase beyond the average size, and no reason why there should not be variations of decrease. I think this expresses your view. I had intended this summer subjecting plants to [illegible] conditions, and observing the effects on variation; but the work would be very laborious, yet I am inclined to think it will be hereafter worth the labour. LETTER 265. TO T. MEEHAN. Down, October 9th, 1874. I am glad that you are attending to the colours of dioecious flowers; but it is well to remember that their colours may be as unimportant to them as those of a gall, or, indeed, as the colour of an amethyst or ruby is to these gems. Some thirty years ago I began to investigate the little purple flowers in the centre of the umbels of the carrot. I suppose my memory is wrong, but it tells me that these flowers are female, and I think that I once got a seed from one of them; but my memory may be quite wrong. I hope that you will continue your interesting researches. LETTER 266. TO G. JAGER. Down, February 3rd, 1875. I received this morning a copy of your work "Contra Wigand," either from yourself or from your publisher, and I am greatly obliged for it. (266/1. Jager's "In Sachen Darwins insbesondere contra Wigand" (Stuttgart, 1874) is directed against A. Wigand's "Der Darwinismus und die Naturforschung Newtons und Cuviers" (Brunswick, 1874).) I had, however, before bought a copy, and have sent the new one to our best library, that of the Royal Society. As I am a very poor german scholar, I have as yet read only about forty pages; but these have interested me in the highest degree. Your remarks on fixed and variable species deserve the greatest attention; but I am not at present quite convinced that there are such independent of the conditions to which they are subjected. I think you have done great service to the principle of evolution, which we both support, by publishing this work. I am the more glad to read it as I had not time to read Wigand's great and tedious volume. LETTER 267. TO CHAUNCEY WRIGHT. Down, March 13th, 1875. I write to-day so that there shall be no delay this time in thanking you for your interesting and long letter received this morning. I am sure that you will excuse brevity when I tell you that I am half-killing myself in trying to get a book ready for the press. (267/1. The MS. of "Insectivorous Plants" was got ready for press in March, 1875. Darwin seems to have been more than usually oppressed by the work.) I quite agree with what you say about advantages of various degrees of importance being co-selected (267/2. Mr. Chauncey Wright wrote (February 24th, 1875): "The inquiry as to which of several real uses is the one through which Natural Selection has acted...has for several years seemed to me a somewhat less important question than it seemed formerly, and still appears to most thinkers on the subject...The uses of the rattling of the rattlesnake as a protection by warning its enemies and as a sexual call are not rival uses; neither are the high-reaching and the far-seeing uses of the giraffe's neck 'rivals.'"), and aided by the effects of use, etc. The subject seems to me well worth further development. I do not think I have anywhere noticed the use of the eyebrows, but have long known that they protected the eyes from sweat. During the voyage of the "Beagle" one of the men ascended a lofty hill during a very hot day. He had small eyebrows, and his eyes became fearfully inflamed from the sweat running into them. The Portuguese inhabitants were familiar with this evil. I think you allude to the transverse furrows on the forehead as a protection against sweat; but remember that these incessantly appear on the foreheads of baboons. P.S.--I have been greatly pleased by the notices in the "Nation." LETTER 268. TO A. WEISMANN. Down, May 1st, 1875. I did not receive your essay for some days after your very kind letter, and I read german so slowly that I have only just finished it. (268/1. "Studien zur Descendenz-Theorie" I. "Ueber den Saison-Dimorphismus," 1875. The fact was previously known that two forms of the genus Vanessa which had been considered to be distinct species are only SEASONAL forms of the same species--one appearing in spring, the other in summer. This remarkable relationship forms the subject of the essay.) Your work has interested me greatly, and your conclusions seem well established. I have long felt much curiosity about season-dimorphism, but never could form any theory on the subject. Undoubtedly your view is very important, as bearing on the general question of variability. When I wrote the "Origin" I could not find any facts which proved the direct action of climate and other external conditions. I long ago thought that the time would soon come when the causes of variation would be fully discussed, and no one has done so much as you in this important subject. The recent evidence of the difference between birds of the same species in the N. and S. United States well shows the power of climate. The two sexes of some few birds are there differently modified by climate, and I have introduced this fact in the last edition of my "Descent of Man." (268/2. "Descent of Man," Edition II. (in one volume), page 423. Allen showed that many species of birds are more strongly coloured in the south of the United States, and that sometimes one sex is more affected than the other. It is this last point that bears on Weismann's remarks (loc. cit., pages 44, 45) on Pieris napi. The males of the alpine-boreal form bryoniae hardly differ from those of the German form (var. vernalis), while the females are strikingly different. Thus the character of secondary sexual differences is determined by climate.) I am, therefore, fully prepared to admit the justness of your criticism on sexual selection of lepidoptera; but considering the display of their beauty, I am not yet inclined to think that I am altogether in error. What you say about reversion (268/3. For instance, the fact that reversion to the primary winter-form may be produced by the disturbing effect of high temperature (page 7).) being excited by various causes, agrees with what I concluded with respect to the remarkable effects of crossing two breeds: namely, that anything which disturbs the constitution leads to reversion, or, as I put the case under my hypothesis of pangenesis, gives a good chance of latent gemmules developing. Your essay, in my opinion, is an admirable one, and I thank you for the interest which it has afforded me. P.S. I find that there are several points, which I have forgotten. Mr. Jenner Weir has not published anything more about caterpillars, but I have written to him, asking him whether he has tried any more experiments, and will keep back this letter till I receive his answer. Mr. Riley of the United States supports Mr. Weir, and you will find reference to him and other papers at page 426 of the new and much-corrected edition of my "Descent of Man." As I have a duplicate copy of Volume I. (I believe Volume II. is not yet published in german) I send it to you by this post. Mr. Belt, in his travels in Nicaragua, gives several striking cases of conspicuously coloured animals (but not caterpillars) which are distasteful to birds of prey: he is an excellent observer, and his book, "The Naturalist in Nicaragua," very interesting. I am very much obliged for your photograph, which I am particularly glad to possess, and I send mine in return. I see you allude to Hilgendorf's statements, which I was sorry to see disputed by some good German observer. Mr. Hyatt, an excellent palaeontologist of the United States, visited the place, and likewise assured me that Hilgendorf was quite mistaken. (268/4. See Letters 252-7.) I am grieved to hear that your eyesight still continues bad, but anyhow it has forced your excellent work in your last essay. May 4th. Here is what Mr. Weir says:-- "In reply to your inquiry of Saturday, I regret that I have little to add to my two communications to the 'Entomological Society Transactions.' "I repeated the experiments with gaudy caterpillars for years, and always with the same results: not on a single occasion did I find richly coloured, conspicuous larvae eaten by birds. It was more remarkable to observe that the birds paid not the slightest attention to gaudy caterpillars, not even when in motion,--the experiments so thoroughly satisfied my mind that I have now given up making them." LETTER 269. TO LAWSON TAIT. (269/1. The late Mr. Lawson Tait wrote to Mr. Darwin (June 2nd, 1875): "I am watching a lot of my mice from whom I removed the tails at birth, and I am coming to the conclusion that the essential use of the tail there is as a recording organ--that is, they record in their memories the corners they turn and the height of the holes they pass through by touching them with their tails." Mr. Darwin was interested in the idea because "some German sneered at Natural Selection and instanced the tails of mice.") June 11th, 1875. It has just occurred to me to look at the "Origin of Species" (Edition VI., page 170), and it is certain that Bronn, in the appended chapter to his translation of my book into german, did advance ears and tail of various species of mice as a difficulty opposed to Natural Selection. I answered with respect to ears by alluding to Schobl's curious paper (I forget when published) (269/2. J. Schobl, "Das aussere Ohr der Mause als wichtiges Tastorgan." "Archiv. Mik. Anat." VII., 1871, page 260.) on the hairs of the ears being sensitive and provided with nerves. I presume he made fine sections: if you are accustomed to such histological work, would it not be worth while to examine hairs of tail of mice? At page 189 I quote Henslow (confirmed by Gunther) on Mus messorius (and other species?) using tail as prehensile organ. Dr. Kane in his account of the second Grinnell Expedition says that the Esquimaux in severe weather carry a fox-tail tied to the neck, which they use as a respirator by holding the tip of the tail between their teeth. (269/3. The fact is stated in Volume II., page 24, of E.K. Kane's "Arctic Explorations: The Second Grinnell Expedition in Search of Sir John Franklin." Philadelphia, 1856.) He says also that he found a frozen fox curled up with his nose buried in his tail. N.B. It is just possible that the latter fact is stated by M'Clintock, not by Dr. Kane. (269/4. The final passage is a postscript by Mr. W.E. Darwin bearing on Mr. Lawson Tait's idea of the respirator function of the fox's tail.) LETTER 270. TO G.J. ROMANES. Down, July 12th, 1875. I am correcting a second edition of "Variation under Domestication," and find that I must do it pretty fully. Therefore I give a short abstract of potato graft-hybrids, and I want to know whether I did not send you a reference about beet. Did you look to this, and can you tell me anything about it? I hope with all my heart that you are getting on pretty well with your experiments. I have been led to think a good deal on the subject, and am convinced of its high importance, though it will take years of hammering before physiologists will admit that the sexual organs only collect the generative elements. The edition will be published in November, and then you will see all that I have collected, but I believe that you gave all the more important cases. The case of vine in "Gardeners' Chronicle," which I sent you, I think may only be a bud-variation not due to grafting. I have heard indirectly of your splendid success with nerves of medusae. We have been at Abinger Hall for a month for rest, which I much required, and I saw there the cut-leaved vine which seems splendid for graft hybridism. LETTER 271. TO FRANCIS GALTON. Down, November 7th, 1875. I have read your essay with much curiosity and interest, but you probably have no idea how excessively difficult it is to understand. (271/1. "A Theory of Heredity" ("Journal of the Anthropological Institute," 1875). In this paper Mr. Galton admits that the hypothesis of organic units "must lie at the foundation of the science of heredity," and proceeds to show in what respect his conception differs from the hypothesis of pangenesis. The copy of Mr. Galton's paper, which Darwin numbered in correspondence with the criticisms in his letter, is not available, and we are therefore only able to guess at some of the points referred to.) I cannot fully grasp, only here and there conjecture, what are the points on which we differ. I daresay this is chiefly due to muddy-headedness on my part, but I do not think wholly so. Your many terms, not defined, "developed germs," "fertile," and "sterile germs" (the word "germ" itself from association misleading to me) "stirp," "sept," "residue," etc., etc., quite confounded me. If I ask myself how you derive, and where you place the innumerable gemmules contained within the spermatozoa formed by a male animal during its whole life, I cannot answer myself. Unless you can make several parts clearer I believe (though I hope I am altogether wrong) that only a few will endeavour or succeed in fathoming your meaning. I have marked a few passages with numbers, and here make a few remarks and express my opinion, as you desire it, not that I suppose it will be of any use to you. 1. If this implies that many parts are not modified by use and disuse during the life of the individual, I differ widely from you, as every year I come to attribute more and more to such agency. (271/2. This seems to refer to page 329 of Mr. Galton's paper. The passage must have been hastily read, and has been quite misunderstood. Mr. Galton has never expressed the view attributed to him.) 2. This seems rather bold, as sexuality has not been detected in some of the lowest forms, though I daresay it may hereafter be. (271/3. Mr. Galton, op. cit., pages 332-3: "There are not of a necessity two sexes, because swarms of creatures of the simplest organisations mainly multiply by some process of self-division.") 3. If gemmules (to use my own term) were often deficient in buds, I cannot but think that bud-variations would be commoner than they are in a state of nature; nor does it seem that bud-variations often exhibit deficiencies which might be accounted for by the absence of the proper gemmules. I take a very different view of the meaning or cause of sexuality. (271/4. Mr. Galton's idea is that in a bud or other asexually produced part, the germs (i.e. gemmules) may not be completely representative of the whole organism, and if reproduction is continued asexually "at each successive stage there is always a chance of some one or more of the various species of germs... dying out" (page 333). Mr. Galton supposes, in sexual reproduction, where two parents contribute germs to the embryo the chance of deficiency of any of the necessary germs is greatly diminished. Darwin's "very different view of the meaning or cause of sexuality" is no doubt that given in "Cross and Self Fertilisation"--i.e., that sexuality is equivalent to changed conditions, that the parents are not representative of different sexes, but of different conditions of life.) 4. I have ordered "Fraser's Magazine" (271/5. "The History of Twins," by F. Galton, "Fraser's Magazine," November, 1875, republished with additions in the "Journal of the Anthropological Institute," 1875. Mr. Galton explains the striking dissimilarity of twins which is sometimes met with by supposing that the offspring in this case divide the available gemmules between them in such a way that each is the complement of the other. Thus, to put the case in an exaggerated way, similar twins would each have half the gemmules A, B, C,...Z., etc, whereas, in the case of dissimilar twins, one would have all the gemmules A, B, C, D,...M, and the other would have N...Z.), and am curious to learn how twins from a single ovum are distinguished from twins from two ova. Nothing seems to me more curious than the similarity and dissimilarity of twins. 5. Awfully difficult to understand. 6. I have given almost the same notion. 7. I hope that all this will be altered. I have received new and additional cases, so that I have now not a shadow of doubt. 8. Such cases can hardly be spoken of as very rare, as you would say if you had received half the number of cases I have. (271/6. We are unable to determine to what paragraphs 5, 6, 7, 8 refer.) I am very sorry to differ so much from you, but I have thought that you would desire my open opinion. Frank is away, otherwise he should have copied my scrawl. I have got a good stock of pods of sweet peas, but the autumn has been frightfully bad; perhaps we may still get a few more to ripen. LETTER 272. TO T.H. HUXLEY. Down, November 12th [1875]. Many thanks for your "Biology," which I have read. (272/1. "A Course of Practical Instruction in Elementary Biology," by T.H. Huxley and H.N. Martin, 1875. For an account of the book see "Life and Letters of T.H. Huxley," Volume I., page 380.) It was a real stroke of genius to think of such a plan. Lord, how I wish I had gone through such a course! LETTER 273. TO FRANCIS GALTON. December 18th [1875]. George has been explaining our differences. I have admitted in the new edition (273/1. In the second edition (1875) of the "Variation of Animals and Plants," Volume II., page 350, reference is made to Mr. Galton's transfusion experiments, "Proc. R. Soc." XIX., page 393; also to Mr. Galton's letter to "Nature," April 27th, 1871, page 502. This is a curious mistake; the letter in "Nature," April 27th, 1871, is by Darwin himself, and refers chiefly to the question whether gemmules may be supposed to be in the blood. Mr. Galton's letter is in "Nature," May 4th, 1871, Volume IV., page 5. See Letter 235.) (before seeing your essay) that perhaps the gemmules are largely multiplied in the reproductive organs; but this does not make me doubt that each unit of the whole system also sends forth its gemmules. You will no doubt have thought of the following objection to your views, and I should like to hear what your answer is. If two plants are crossed, it often, or rather generally, happens that every part of stem, leaf, even to the hairs, and flowers of the hybrid are intermediate in character; and this hybrid will produce by buds millions on millions of other buds all exactly reproducing the intermediate character. I cannot doubt that every unit of the hybrid is hybridised and sends forth hybridised gemmules. Here we have nothing to do with the reproductive organs. There can hardly be a doubt from what we know that the same thing would occur with all those animals which are capable of budding, and some of these (as the compound Ascidians) are sufficiently complex and highly organised. LETTER 274. TO LAWSON TAIT. March 25th, 1876. (274/1. The reference is to the theory put forward in the first edition of "Variation of Animals and Plants," II., page 15, that the asserted tendency to regeneration after the amputation of supernumerary digits in man is a return to the recuperative powers characteristic of a "lowly organised progenitor provided with more than five digits." Darwin's recantation is at Volume I., page 459 of the second edition.) Since reading your first article (274/2. Lawson Tait wrote two notices on "The Variation of Animals and Plants under Domestication" in the "Spectator" of March 4th, 1876, page 312, and March 25th, page 406.), Dr. Rudinger has written to me and sent me an essay, in which he gives the results of the MOST EXTENSIVE inquiries from all eminent surgeons in Germany, and all are unanimous about non-growth of extra digits after amputation. They explain some apparent cases, as Paget did to me. By the way, I struck out of my second edition a quotation from Sir J. Simpson about re-growth in the womb, as Paget demurred, and as I could not say how a rudiment of a limb due to any cause could be distinguished from an imperfect re-growth. Two or three days ago I had another letter from Germany from a good naturalist, Dr. Kollmann (274/3. Dr. Kollmann was Secretary of the Anthropologische Gesellschaft of Munich, in which Society took place the discussion referred to in "Variation of Animals and Plants," I., 459, as originating Darwin's doubts on the whole question. The fresh evidence adduced by Kollmann as to the normal occurrence of a rudimentary sixth digit in Batrachians is Borus' paper, "Die sechste Zehe der Anuren" in "Morpholog. Jahrbuch," Bd. I., page 435. On this subject see Letter 178.), saying he was sorry that I had given up atavism and extra digits, and telling me of new and good evidence of rudiments of a rudimentary sixth digit in Batrachians (which I had myself seen, but given up owing to Gegenbaur's views); but, with re-growth failing me, I could not uphold my old notion. LETTER 275. TO G.J. ROMANES. (275/1. Mr. Romanes' reply to this letter is printed in his "Life and Letters," page 93, where by an oversight it is dated 1880-81.) H. Wedgwood, Esq., Hopedene, Dorking, May 29th [1876]. As you are interested in pangenesis, and will some day, I hope, convert an "airy nothing" into a substantial theory, I send by this post an essay by Hackel (275/2. "Die Perigenesis der Plastidule oder die Wellenzeugung der Lebenstheilchen," 79 pages. Berlin, 1876.) attacking Pan. and substituting a molecular hypothesis. If I understand his views rightly, he would say that with a bird which strengthened its wings by use, the formative protoplasm of the strengthened parts became changed, and its molecular vibrations consequently changed, and that these vibrations are transmitted throughout the whole frame of the bird, and affect the sexual elements in such a manner that the wings of the offspring are developed in a like strengthened manner. I imagine he would say, in cases like those of Lord Morton's mare (275/3. A nearly pure-bred Arabian chestnut mare bore a hybrid to a quagga, and subsequently produced two striped colts by a black Arabian horse: see "Animals and Plants," I., page 403. The case was originally described in the "Philosophical Transactions," 1821, page 20. For an account of recent work bearing on this question, see article on "Zebras, Horses, and Hybrids," in the "Quarterly Review," October 1899. See Letter 235.), that the vibrations from the protoplasm, or "plasson," of the seminal fluid of the zebra set plasson vibrating in the mare; and that these vibrations continued until the hair of the second colt was formed, and which consequently became barred like that of a zebra. How he explains reversion to a remote ancestor, I know not. Perhaps I have misunderstood him, though I have skimmed the whole with some care. He lays much stress on inheritance being a form of unconscious memory, but how far this is part of his molecular vibration, I do not understand. His views make nothing clearer to me; but this may be my fault. No one, I presume, would doubt about molecular movements of some kind. His essay is clever and striking. If you read it (but you must not on my account), I should much like to hear your judgment, and you can return it at any time. The blue lines are Hackel's to call my attention. We have come here for rest for me, which I have much needed; and shall remain here for about ten days more, and then home to work, which is my sole pleasure in life. I hope your splendid Medusa work and your experiments on pangenesis are going on well. I heard from my son Frank yesterday that he was feverish with a cold, and could not dine with the physiologists, which I am very sorry for, as I should have heard what they think about the new Bill. I see that you are one of the secretaries to this young Society. LETTER 276. TO H.N. MOSELEY. Down, November 22nd [1876]. It is very kind of you to send me the Japanese books, which are extremely curious and amusing. My son Frank is away, but I am sure he will be much obliged for the two papers which you have sent him. Thanks, also, for your interesting note. It is a pity that Peripatus (276/1. Moseley "On the Structure and Development of Peripatus capensis" ("Phil. Trans. R. Soc." Volume 164, page 757, 1874). "When suddenly handled or irritated, they (i.e. Peripatus) shoot out fine threads of a remarkably viscid and tenacious milky fluid... projected from the tips of the oral papillae" (page 759).) is so stupid as to spit out the viscid matter at the wrong end of its body; it would have been beautiful thus to have explained the origin of the spider's web. LETTER 277. NAPHTALI LEWY TO CHARLES DARWIN. (277/1. The following letter refers to a book, "Toledoth Adam," written by a learned Jew with the object of convincing his co-religionists of the truth of the theory of evolution. The translation we owe to the late Henry Bradshaw, University Librarian at Cambridge. The book is unfortunately no longer to be found in Mr. Darwin's library.) [1876]. To the Lord, the Prince, who "stands for an ensign of the people" (Isa. xi. 10), the Investigator of the generation, the "bright son of the morning" (Isa. xiv. 12), Charles Darwin, may he live long! "From the rising of the sun and from the west" (Isa. xlv. 6) all the nations know concerning the Torah (Theory) (277/2. Lit., instruction. The Torah is the Pentateuch, strictly speaking, the source of all knowledge.) which has "proceeded from thee for a light of the people" (Isa. li. 4), and the nations "hear and say, It is truth" (Isa. xliii. 9). But with "the portion of my people" (Jer. x. 16), Jacob, "the lot of my inheritance" (Deut. xxxii. 9), it is not so. This nation, "the ancient people" (Isa. xliv. 7), which "remembers the former things and considers the things of old (Isa. xliii. 18), "knows not, neither doth it understand" (Psalm lxxxii. 5), that by thy Torah (instruction or theory) thou hast thrown light upon their Torah (the Law), and that the eyes of the Hebrews (277/3. One letter in this word changed would make the word "blind," which is what Isaiah uses in the passage alluded to.) "can now see out of obscurity and out of darkness" (Isa. xxix. 18). Therefore "I arose" (Judges v. 7) and wrote this book, "Toledoth Adam" ("the generations of man," Gen. v. 1), to teach the children of my people, the seed of Jacob, the Torah (instruction) which thou hast given for an inheritance to all the nations of the earth. And I have "proceeded to do a marvellous work among this people, even a marvellous work and a wonder" (Isa. xxix. 14), enabling them now to read in the Torah of Moses our teacher, "plainly and giving the sense" (Neh. viii. 8), that which thou hast given in thy Torahs (works of instruction). And when my people perceive that thy view has by no means "gone astray" (Num. v. 12, 19, etc.) from the Torah of God, they will hold thy name in the highest reverence, and "will at the same time glorify the God of Israel" (Isa. xxix. 23). "The vision of all this" (Isa. xxix. 11) thou shalt see, O Prince of Wisdom, in this book, "which goeth before me" (Gen. xxxii. 21); and whatever thy large understanding finds to criticise in it, come, "write it in a table and note it in a book" (Isa. xxx. 8); and allow me to name my work with thy name, which is glorified and greatly revered by Thy servant, Naphtali Hallevi [i.e. the Levite]. Dated here in the city of Radom, in the province of Poland, in the month of Nisan in the year 636, according to the lesser computation (i.e. A.M. [5]636 = A.D. 1876). LETTER 278. TO OTTO ZACHARIAS. 1877. When I was on board the "Beagle" I believed in the permanence of species, but, as far as I can remember, vague doubts occasionally flitted across my mind. On my return home in the autumn of 1836 I immediately began to prepare my journal for publication, and then saw how many facts indicated the common descent of species (278/1. "The facts to which reference is here made were, without doubt, eminently fitted to attract the attention of a philosophical thinker; but until the relations of the existing with the extinct species and of the species of the different geographical areas, with one another were determined with some exactness, they afforded but an unsafe foundation for speculation. It was not possible that this determination should have been effected before the return of the "Beagle" to England; and thus the date which Darwin (writing in 1837) assigns to the dawn of the new light which was rising in his mind becomes intelligible."--From "Darwiniana," Essays by Thomas H. Huxley, London, 1893; pages 274-5.), so that in July, 1837, I opened a notebook to record any facts which might bear on the question; but I did not become convinced that species were mutable until, I think, two or three years had elapsed. (278/2. On this last point see page 38.) LETTER 279. TO G.J. ROMANES. (279/1. The following letter refers to MS. notes by Romanes, which we have not seen. Darwin's remarks on it are, however, sufficiently clear.) My address will be "Bassett, Southampton," June 11th [1877]. I have received the crossing paper which you were so kind as to send me. It is very clear, and I quite agree with it; but the point in question has not been a difficulty to me, as I have never believed in a new form originating from a single variation. What I have called unconscious selection by man illustrates, as it seems to me, the same principle as yours, within the same area. Man purchases the individual animals or plants which seem to him the best in any respect--some more so, and some less so--and, without any matching or pairing, the breed in the course of time is surely altered. The absence in numerous instances of intermediate or blending forms, in the border country between two closely allied geographical races or close species, seemed to me a greater difficulty when I discussed the subject in the "Origin." With respect to your illustration, it formerly drove me half mad to attempt to account for the increase or diminution of the productiveness of an organism; but I cannot call to mind where my difficulty lay. (279/2. See Letters 209-16.) Natural Selection always applies, as I think, to each individual and its offspring, such as its seeds, eggs, which are formed by the mother, and which are protected in various ways. (279/3. It was in regard to this point that Romanes had sent the MS. to Darwin. In a letter of June 16th he writes: "It was with reference to the possibility of Natural Selection acting on organic types as distinguished from individuals,--a possibility which you once told me did not seem at all clear.") There does not seem any difficulty in understanding how the productiveness of an organism might be increased; but it was, as far as I can remember, in reducing productiveness that I was most puzzled. But why I scribble about this I know not. I have read your review of Mr. Allen's book (279/4. See "Nature" (June 7th, 1877, page 98), a review of Grant Allen's "Physiological Aesthetics."), and it makes me more doubtful, even, than I was before whether he has really thrown much light on the subject. I am glad to hear that some physiologists take the same view as I did about your giving too much credit to H. Spencer--though, heaven knows, this is a rare fault. (279/5. The reference is to Romanes' lecture on Medusa, given at the Royal Institution, May 25th. (See "Nature," XVI., pages 231, 269, 289.) It appears from a letter of Romanes (June 6th) that it was the abstract in the "Times" that gave the impression referred to. References to Mr. Spencer's theories of nerve-genesis occur in "Nature," pages 232, 271, 289.) The more I think of your medusa-nerve-work the more splendid it seems to me. LETTER 280. TO A. DE CANDOLLE. Down, August 3rd, 1877. I must have the pleasure of thanking you for your long and interesting letter. The cause and means of the transition from an hermaphrodite to a unisexual condition seems to me a very perplexing problem, and I shall be extremely glad to read your remarks on Smilax, whenever I receive the essay which you kindly say that you will send me. (280/1. "Monographiae Phanerogamarum," Volume I. In his treatment of the Smilaceae, De Candolle distinguishes:--Heterosmilax which has dioecious flowers without a trace of aborted stamens or pistils, Smilax with sterile stamens in the female flowers, and Rhipogonum with hermaphrodite flowers.) There is much justice in your criticisms (280/2. The passage criticised by De Candolle is in "Forms of Flowers" (page 7): "It is a natural inference that their corollas have been increased in size for this special purpose." De Candolle goes on to give an account of the "recherche linguistique," which, with characteristic fairness, he undertook to ascertain whether the word "purpose" differs in meaning from the corresponding French word "but.") on my use of the terms object, end, purpose; but those who believe that organs have been gradually modified for Natural Selection for a special purpose may, I think, use the above terms correctly, though no conscious being has intervened. I have found much difficulty in my occasional attempts to avoid these terms, but I might perhaps have always spoken of a beneficial or serviceable effect. My son Francis will be interested by hearing about Smilax. He has dispatched to you a copy of his paper on the glands of Dipsacus (280/3. "Quart. Journ. Mic. Sci." 1877.), and I hope that you will find time to read it, for the case seems to me a new and highly remarkable one. We are now hard at work on an attempt to make out the function or use of the bloom or waxy secretion on the leaves and fruit of many plants; but I doubt greatly whether our experiments will tell us much. (280/4. "As it is we have made out clearly that with some plants (chiefly succulent) the bloom checks evaporation--with some certainly prevents attacks of insects; with some sea-shore plants prevents injury from salt-water, and I believe, with a few prevents injury from pure water resting on the leaves." (See letter to Sir W. Thiselton-Dyer, "Life and Letters," III., page 341. A paper on the same subject by Francis Darwin was published in the "Journ. Linn. Soc." XXII.)) If you have any decided opinion whether plants with conspicuously glaucous leaves are more frequent in hot than in temperate or cold, in dry than in damp countries, I should be grateful if you would add to your many kindnesses by informing me. Pray give my kind remembrances to your son, and tell him that my son has been trying on a large scale the effects of feeding Drosera with meat, and the results are most striking and far more favourable than I anticipated. LETTER 281. TO G.J. ROMANES. (281/1. Published in the "Life and Letters" of Romanes, page 66.) Down, Saturday Night [1877]. I have just finished your lecture (281/2. "The Scientific Evidence of Organic Evolution: a Discourse" (delivered before the Philosophical Society of Ross-shire), Inverness, 1877. It was reprinted in the "Fortnightly Review," and was afterwards worked up into a book under the above title.); it is an admirable scientific argument, and most powerful. I wish that it could be sown broadcast throughout the land. Your courage is marvellous, and I wonder that you were not stoned on the spot--and in Scotland! Do please tell me how it was received in the Lecture Hall. About man being made like a monkey (page 37 (281/3. "And if you reject the natural explanation of hereditary descent, you can only suppose that the Deity, in creating man, took the most scrupulous pains to make him in the image of the ape" ("Discourse," page 37).)) is quite new to me, and the argument in an earlier place (page 8 (281/4. At page 8 of the "Discourse" the speaker referred to the law "which Sir William Hamilton called the Law of Parsimony--or the law which forbids us to assume the operation of higher causes when lower ones are found sufficient to explain the desired effects," as constituting the "only logical barrier between Science and Superstition.")) on the law of parsimony admirably put. Yes, page 21 (281/5. "Discourse," page 21. If we accept the doctrines of individual creations and ideal types, we must believe that the Deity acted "with no other apparent motive than to suggest to us, by every one of the observable facts, that the ideal types are nothing other than the bonds of a lineal descent.") is new to me. All strike me as very clear, and, considering small space, you have chosen your lines of reasoning excellently. The few last pages are awfully powerful, in my opinion. Sunday Morning.--The above was written last night in the enthusiasm of the moment, and now--this dark, dismal Sunday morning--I fully agree with what I said. I am very sorry to hear about the failures in the graft experiments, and not from your own fault or ill-luck. Trollope in one of his novels gives as a maxim of constant use by a brickmaker--"It is dogged as does it" (281/6. "Tell 'ee what, Master Crawley;--and yer reverence mustn't think as I means to be preaching; there ain't nowt a man can't bear if he'll only be dogged. You go whome, Master Crawley, and think o' that, and may be it'll do ye a good yet. It's dogged as does it. It ain't thinking about it." (Giles Hoggett, the old Brickmaker, in "The Last Chronicle of Barset," Volume II., 1867, page 188.))--and I have often and often thought that this is the motto for every scientific worker. I am sure it is yours--if you do not give up pangenesis with wicked imprecations. By the way, G. Jager has brought out in "Kosmos" a chemical sort of pangenesis bearing chiefly on inheritance. (281/7. Several papers by Jager on "Inheritance" were published in the first volume of "Kosmos," 1877.) I cannot conceive why I have not offered my garden for your experiments. I would attend to the plants, as far as mere care goes, with pleasure; but Down is an awkward place to reach. Would it be worth while to try if the "Fortnightly" would republish it [i.e. the lecture]? LETTER 282. TO T.H. HUXLEY. (282/1. In 1877 the honorary degree of LL.D. was conferred on Mr. Darwin by the University of Cambridge. At the dinner given on the occasion by the Philosophical Society, Mr. Huxley responded to the toast of the evening with the speech of which an authorised version is given by Mr. L. Huxley in the "Life and Letters" of his father (Volume I., page 479). Mr. Huxley said, "But whether the that doctrine [of evolution] be true or whether it be false, I wish to express the deliberate opinion, that from Aristotle's great summary of the biological knowledge of his time down to the present day, there is nothing comparable to the "Origin of Species," as a connected survey of the phenomena of life permeated and vivified by a central idea." In the first part of the speech there was a brilliant sentence which he described as a touch of the whip "tied round with ribbons," and this was perhaps a little hard on the supporters of evolution in the University. Mr. Huxley said "Instead of offering her honours when they ran a chance of being crushed beneath the accumulated marks of approbation of the whole civilised world, the University has waited until the trophy was finished, and has crowned the edifice with the delicate wreath of academic appreciation.") Down, Monday night, November 19th [1877]. I cannot rest easy without telling you more gravely than I did when we met for five minutes near the Museum, how deeply I have felt the many generous things (as far as Frank could remember them) which you said about me at the dinner. Frank came early next morning boiling over with enthusiasm about your speech. You have indeed always been to me a most generous friend, but I know, alas, too well how greatly you overestimate me. Forgive me for bothering you with these few lines. (282/2. The following extract from a letter (February 10th, 1878) to his old schoolfellow, Mr. J. Price, gives a characteristic remark about the honorary degree.) "I am very much obliged for your kind congratulations about the LL.D. Why the Senate conferred it on me I know not in the least. I was astonished to hear that the R. Prof. of Divinity and several other great Dons attended, and several such men have subscribed, as I am informed, for the picture for the University to commemorate the honour conferred on me." LETTER 283. TO W. BOWMAN. (283/1. We have not discovered to what prize the following letter to the late Sir W. Bowman (the well known surgeon) refers.) Down, February 22nd, 1878. I received your letter this morning, and it was quite impossible that you should receive an answer by 4 p.m. to-day. But this does not signify in the least, for your proposal seems to me a very good one, and I most entirely agree with you that it is far better to suggest some special question rather than to have a general discussion compiled from books. The rule that the Essay must be "illustrative of the wisdom and beneficence of the Almighty" would confine the subjects to be proposed. With respect to the Vegetable Kingdom, I could suggest two or three subjects about which, as it seems to me, information is much required; but these subjects would require a long course of experiment, and unfortunately there is hardly any one in this country who seems inclined to devote himself to experiments. LETTER 284. TO J. TORBITT. (284/1. Mr. Torbitt was engaged in trying to produce by methodical selection and cross-fertilisation a fungus-proof race of the potato. The plan is fully described in the "Life and Letters," III., page 348. The following letter is given in additional illustration of the keen interest Mr. Darwin took in the project.) Down, Monday, March 4th, 1878. I have nothing good to report. Mr. Caird called upon me yesterday; both he and Mr. Farrer (284/2. The late Lord Farrer.) have been most energetic and obliging. There is no use in thinking about the Agricultural Society. Mr. Caird has seen several persons on the subject, especially Mr. Carruthers, Botanist to the Society. He (Mr. Carruthers) thinks the attempt hopeless, but advances in a long memorandum sent to Mr. Caird, reasons which I am convinced are not sound. He specifies two points, however, which are well worthy of your consideration--namely, that a variety should be tested three years before its soundness can be trusted; and especially it should be grown under a damp climate. Mr. Carruthers' opinion on this head is valuable because he was employed by the Society in judging the varieties sent in for the prize offered a year or two ago. If I had strength to get up a memorial to Government, I believe that I could succeed; for Sir J. Hooker writes that he believes you are on the right path; but I do not know to whom else to apply whose judgment would have weight with Government, and I really have not strength to discuss the matter and convert persons. At Mr. Farrer's request, when we hoped the Agricultural Society might undertake it, I wrote to him a long letter giving him my opinion on the subject; and this letter Mr. Caird took with him yesterday, and will consider with Mr. Farrer whether any application can be made to Government. I am, however, far from sanguine. I shall see Mr. Farrer this evening, and will do what I can. When I receive back my letter I will send it to you for your perusal. After much reflection it seems to me that your best plan will be, if we fail to get Government aid, to go on during the present year, on a reduced scale, in raising new cross-fertilised varieties, and next year, if you are able, testing the power of endurance of only the most promising kind. If it were possible it would be very advisable for you to get some grown on the wet western side of Ireland. If you succeed in procuring a fungus-proof variety you may rely on it that its merits would soon become known locally and it would afterwards spread rapidly far and wide. Mr. Caird gave me a striking instance of such a case in Scotland. I return home to-morrow morning. I have the pleasure to enclose a cheque for 100 pounds. If you receive a Government grant, I ought to be repaid. P.S. If I were in your place I would not expend any labour or money in publishing what you have already done, or in sending seeds or tubers to any one. I would work quietly on till some sure results were obtained. And these would be so valuable that your work in this case would soon be known. I would also endeavour to pass as severe a judgment as possible on the state of the tubers and plants. LETTER 285. TO E. VON MOJSISOVICS. Down, June 1st, 1878. I have at last found time to read [the] first chapter of your "Dolomit Riffe" (285/1. "Dolomitriffe Sudtirols und Venetiens." Wien, 1878.), and have been exceedingly interested by it. What a wonderful change in the future of geological chronology you indicate, by assuming the descent-theory to be established, and then taking the graduated changes of the same group of organisms as the true standard! I never hoped to live to see such a step even proposed by any one. (285/2. Published in "Life and Letters," III., pages 234, 235.) Nevertheless, I saw dimly that each bed in a formation could contain only the organisms proper to a certain depth, and to other there existing conditions, and that all the intermediate forms between one marine species and another could rarely be preserved in the same place and bed. Oppel, Neumayr, and yourself will confer a lasting and admirable service on the noble science of Geology, if you can spread your views so as to be generally known and accepted. With respect to the continental and oceanic periods common to the whole northern hemisphere, to which you refer, I have sometimes speculated that the present distribution of the land and sea over the world may have formerly been very different to what it now is; and that new genera and families may have been developed on the shores of isolated tracts in the south, and afterwards spread to the north. LETTER 286. TO J.W. JUDD. Down, June 27th, 1878. I am heartily glad to hear of your intended marriage. A good wife is the supreme blessing in this life, and I hope and believe from what you say that you will be as happy as I have been in this respect. May your future geological work be as valuable as that which you have already done; and more than this need not be wished for any man. The practical teaching of Geology seems an excellent idea. Many thanks for Neumayr, (286/1. Probably a paper on "Die Congerien und Paludinenschichten Slavoniens und deren Fauna. Ein Beitrag zur Descendenz-Theorie," "Wien. Geol. Abhandl." VII. (Heft 3), 1874-82.), but I have already received and read a copy of the same, or at least of a very similar essay, and admirably good it seemed to me. This essay, and one by Mojsisovics (286/2. See note to Letter 285.), which I have lately read, show what Palaeontology in the future will do for the classification and sequence of formations. It delighted me to see so inverted an order of proceeding--viz., the assuming the descent of species as certain, and then taking the changes of closely allied forms as the standard of geological time. My health is better than it was a few years ago, but I never pass a day without much discomfort and the sense of extreme fatigue. (286/3. We owe to Professor Judd the following interesting recollections of Mr. Darwin, written about 1883:-- "On this last occasion, when I congratulated him on his seeming better condition of health, he told me of the cause for anxiety which he had in the state of his heart. Indeed, I cannot help feeling that he had a kind of presentiment that his end was approaching. When I left him, he insisted on conducting me to the door, and there was that in his tone and manner which seemed to convey to me the sad intelligence that it was not merely a temporary farewell, though he himself was perfectly cheerful and happy. "It is impossible for me adequately to express the impression made upon my mind by my various conversations with Mr. Darwin. His extreme modesty led him to form the lowest estimate of his own labours, and a correspondingly extravagant idea of the value of the work done by others. His deference to the arguments and suggestions of men greatly his juniors, and his unaffected sympathy in their pursuits, was most marked and characteristic; indeed, he, the great master of science, used to speak, and I am sure felt, as though he were appealing to superior authority for information in all his conversations. It was only when a question was fully discussed with him that one became conscious of the fund of information he could bring to its elucidation, and the breadth of thought with which he had grasped it. Of his gentle, loving nature, of which I had so many proofs, I need not write; no one could be with him, even for a few minutes, without being deeply impressed by his grateful kindliness and goodness.") LETTER 287. TO COUNT SAPORTA. Down, August 15th, 1878. I thank you very sincerely for your kind and interesting letter. It would be false in me to pretend that I care very much about my election to the Institute, but the sympathy of some few of my friends has gratified me deeply. I am extremely glad to hear that you are going to publish a work on the more ancient fossil plants; and I thank you beforehand for the volume which you kindly say that you will send me. I earnestly hope that you will give, at least incidentally, the results at which you have arrived with respect to the more recent Tertiary plants; for the close gradation of such forms seems to me a fact of paramount importance for the principle of evolution. Your cases are like those on the gradation in the genus Equus, recently discovered by Marsh in North America. LETTER 288. TO THE DUKE OF ARGYLL. (288/1. The following letter was published in "Nature," March 5th, 1891, Volume XLIII., page 415, together with a note from the late Duke of Argyll, in which he stated that the letter had been written to him by Mr. Darwin in reply to the question, "why it was that he did assume the unity of mankind as descended from a single pair." The Duke added that in the reply Mr. Darwin "does not repudiate this interpretation of his theory, but simply proceeds to explain and to defend the doctrine." On a former occasion the Duke of Argyll had "alluded as a fact to the circumstance that Charles Darwin assumed mankind to have arisen at one place, and therefore in a single pair." The letter from Darwin was published in answer to some scientific friends, who doubted the fact and asked for the reference on which the statement was based.) Down, September 23rd, 1878. The problem which you state so clearly is a very interesting one, on which I have often speculated. As far as I can judge, the improbability is extreme that the same well-characterised species should be produced in two distinct countries, or at two distinct times. It is certain that the same variation may arise in two distinct places, as with albinism or with the nectarine on peach-trees. But the evidence seems to me overwhelming that a well-marked species is the product, not of a single or of a few variations, but of a long series of modifications, each modification resulting chiefly from adaptation to infinitely complex conditions (including the inhabitants of the same country), with more or less inheritance of all the preceding modifications. Moreover, as variability depends more on the nature of the organism than on that of the environment, the variations will tend to differ at each successive stage of descent. Now it seems to me improbable in the highest degree that a species should ever have been exposed in two places to infinitely complex relations of exactly the same nature during a long series of modifications. An illustration will perhaps make what I have said clearer, though it applies only to the less important factors of inheritance and variability, and not to adaptation--viz., the improbability of two men being born in two countries identical in body and mind. If, however, it be assumed that a species at each successive stage of its modification was surrounded in two distinct countries or times, by exactly the same assemblage of plants and animals, and by the same physical conditions, then I can see no theoretical difficulty [in] such a species giving birth to the new form in the two countries. If you will look to the sixth edition of my "Origin," at page 100, you will find a somewhat analogous discussion, perhaps more intelligible than this letter. LETTER 289. W.T. THISELTON-DYER TO THE EDITOR OF "NATURE." (289/1. The following letter ("Nature," Volume XLIII., page 535) criticises the interpretation given by the Duke to Mr. Darwin's letter.) Royal Gardens, Kew, March 27th [1891]. In "Nature" of March 5th (page 415), the Duke of Argyll has printed a very interesting letter of Mr. Darwin's, from which he drew the inference that the writer "assumed mankind to have arisen...in a single pair." I do not think myself that the letter bears this interpretation. But the point in its most general aspect is a very important one, and is often found to present some difficulty to students of Mr. Darwin's writings. Quite recently I have found by accident, amongst the papers of the late Mr. Bentham at Kew, a letter of friendly criticism from Mr. Darwin upon the presidential address which Mr. Bentham delivered to the Linnean Society on May 24th, 1869. This letter, I think, has been overlooked and not published previously. In it Mr. Darwin expresses himself with regard to the multiple origin of races and some other points in very explicit language. Prof. Meldola, to whom I mentioned in conversation the existence of the letter, urged me strongly to print it. This, therefore, I now do, with the addition of a few explanatory notes. LETTER 290. TO G. BENTHAM. Down, November 25th, 1869. (290/1. The notes to this letter are by Sir W. Thiselton-Dyer, and appeared in "Nature," loc. cit.) I was greatly interested by your address, which I have now read thrice, and which I believe will have much influence on all who read it. But you are mistaken in thinking that I ever said you were wrong on any point. All that I meant was that on certain points, and these very doubtful points, I was inclined to differ from you. And now, on further considering the point on which some two or three months ago I felt most inclined to differ--viz., on isolation--I find I differ very little. What I have to say is really not worth saying, but as I should be very sorry not to do whatever you asked, I will scribble down the slightly dissentient thoughts which have occurred to me. It would be an endless job to specify the points in which you have interested me; but I may just mention the relation of the extreme western flora of Europe (some such very vague thoughts have crossed my mind, relating to the Glacial period) with South Africa, and your remarks on the contrast of passive and active distribution. Page lxx.--I think the contingency of a rising island, not as yet fully stocked with plants, ought always to be kept in mind when speaking of colonisation. Page lxxiv.--I have met with nothing which makes me in the least doubt that large genera present a greater number of varieties relatively to their size than do small genera. (290/2. Bentham thought "degree of variability... like other constitutional characters, in the first place an individual one, which...may become more or less hereditary, and therefore specific; and thence, but in a very faint degree, generic." He seems to mean to argue against the conclusion which Sir Joseph Hooker had quoted from Mr. Darwin that "species of large genera are more variable than those of small." [On large genera varying, see Letter 53.]) Hooker was convinced by my data, never as yet published in full, only abstracted in the "Origin." Page lxxviii.--I dispute whether a new race or species is necessarily, or even generally, descended from a single or pair of parents. The whole body of individuals, I believe, become altered together--like our race-horses, and like all domestic breeds which are changed through "unconscious selection" by man. (290/3. Bentham had said: "We must also admit that every race has probably been the offspring of one parent or pair of parents, and consequently originated in one spot." The Duke of Argyll inverts the proposition.) When such great lengths of time are considered as are necessary to change a specific form, I greatly doubt whether more or less rapid powers of multiplication have more than the most insignificant weight. These powers, I think, are related to greater or less destruction in early life. Page lxxix.--I still think you rather underrate the importance of isolation. I have come to think it very important from various grounds; the anomalous and quasi-extinct forms on islands, etc., etc., etc. With respect to areas with numerous "individually durable" forms, can it be said that they generally present a "broken" surface with "impassable barriers"? This, no doubt, is true in certain cases, as Teneriffe. But does this hold with South-West Australia or the Cape? I much doubt. I have been accustomed to look at the cause of so many forms as being partly an arid or dry climate (as De Candolle insists) which indirectly leads to diversified [?] conditions; and, secondly, to isolation from the rest of the world during a very long period, so that other more dominant forms have not entered, and there has been ample time for much specification and adaptation of character. Page lxxx.--I suppose you think that the Restiaceae, Proteaceae (290/4. It is doubtful whether Bentham did think so. In his 1870 address he says: "I cannot resist the opinion that all presumptive evidence is against European Proteaceae, and that all direct evidence in their favour has broken down upon cross-examination."), etc., etc., once extended over the world, leaving fragments in the south. You in several places speak of distribution of plants as if exclusively governed by soil and climate. I know that you do not mean this, but I regret whenever a chance is omitted of pointing out that the struggle with other plants (and hostile animals) is far more important. I told you that I had nothing worth saying, but I have given you my THOUGHTS. How detestable are the Roman numerals! why should not the President's addresses, which are often, and I am sure in this case, worth more than all the rest of the number, be paged with Christian figures? LETTER 291. TO R. MELDOLA. (291/1. "This letter was in reply to a suggestion that in his preface Mr. Darwin should point out by references to "The Origin of Species" and his other writings how far he had already traced out the path which Weismann went over. The suggestion was made because in a great many of the continental writings upon the theory of descent, many of the points which had been clearly foreshadowed, and in some cases even explicitly stated by Darwin, had been rediscovered and published as though original. In the notes to my edition of Weismann I have endeavoured to do Darwin full justice.--R.M." See Letter 310.) 4, Bryanston Street, November 26th, 1878. I am very sorry to say that I cannot agree to your suggestion. An author is never a fit judge of his own work, and I should dislike extremely pointing out when and how Weismann's conclusions and work agreed with my own. I feel sure that I ought not to do this, and it would be to me an intolerable task. Nor does it seem to me the proper office of the preface, which is to show what the book contains, and that the contents appear to me valuable. But I can see no objection for you, if you think fit, to write an introduction with remarks or criticisms of any kind. Of course, I would be glad to advise you on any point as far as lay in my power, but as a whole I could have nothing to do with it, on the grounds above specified, that an author cannot and ought not to attempt to judge his own works, or compare them with others. I am sorry to refuse to do anything which you wish. LETTER 292. TO T.H. HUXLEY. Down, January 18th, 1879. I have just finished your present of the Life of Hume (292/1. "Hume" in Mr. Morley's "English Men of Letters" series. Of the biographical part of this book Mr. Huxley wrote, in a letter to Mr. Skelton, January 1879 ("Life of T.H. Huxley," II., page 7): "It is the nearest approach to a work of fiction of which I have yet been guilty."), and must thank you for the great pleasure which it has given me. Your discussions are, as it seems to me, clear to a quite marvellous degree, and many of the little interspersed flashes of wit are delightful. I particularly enjoyed the pithy judgment in about five words on Comte. (292/2. Possibly the passage referred to is on page 52.) Notwithstanding the clearness of every sentence, the subjects are in part so difficult that I found them stiff reading. I fear, therefore, that it will be too stiff for the general public; but I heartily hope that this will prove to be a mistake, and in this case the intelligence of the public will be greatly exalted in my eyes. The writing of this book must have been awfully hard work, I should think. LETTER 293. TO F. MULLER. Down, March 4th [1879]. I thank you cordially for your letter. Your facts and discussion on the loss of the hairs on the legs of the caddis-flies seem to me the most important and interesting thing which I have read for a very long time. I hope that you will not disapprove, but I have sent your letter to "Nature" (293/1. Fritz Muller, "On a Frog having Eggs on its Back--On the Abortion of the Hairs on the Legs of certain Caddis-Flies, etc.": Muller's letter and one from Charles Darwin were published in "Nature," Volume XIX., page 462, 1879.), with a few prefatory remarks, pointing out to the general reader the importance of your view, and stating that I have been puzzled for many years on this very point. If, as I am inclined to believe, your view can be widely extended, it will be a capital gain to the doctrine of evolution. I see by your various papers that you are working away energetically, and, wherever you look, you seem to discover something quite new and extremely interesting. Your brother also continues to do fine work on the fertilisation of flowers and allied subjects. I have little or nothing to tell you about myself. I go slowly crawling on with my present subject--the various and complicated movements of plants. I have not been very well of late, and am tired to-day, so will write no more. With the most cordial sympathy in all your work, etc. LETTER 294. TO T.H. HUXLEY. Down, April 19th, 1879. Many thanks for the book. (294/1. Ernst Hackel's "Freedom in Science and Teaching," with a prefatory note by T.H. Huxley, 1879. Professor Hackel has recently published (without permission) a letter in which Mr. Darwin comments severely on Virchow. It is difficult to say which would have pained Mr. Darwin more--the affront to a colleague, or the breach of confidence in a friend.) I have read only the preface...It is capital, and I enjoyed the tremendous rap on the knuckles which you gave Virchow at the close. What a pleasure it must be to write as you can do! LETTER 295. TO E.S. MORSE. Down, October 21st, 1879. Although you are so kind as to tell me not to write, I must just thank you for the proofs of your paper, which has interested me greatly. (295/1. See "The Shell Mounds of Omori" in the "Memoirs of the Science Department of the Univ. of Tokio," Volume I., Part I., 1879. The ridges on Arca are mentioned at page 25. In "Nature," April 15th, 1880, Mr. Darwin published a letter by Mr. Morse relating to the review of the above paper, which appeared in "Nature," XXI., page 350. Mr. Darwin introduces Mr. Morse's letter with some prefatory remarks. The correspondence is republished in the "American Naturalist," September, 1880.) The increase in the number of ridges in the three species of Arca seems to be a very noteworthy fact, as does the increase of size in so many, yet not all, the species. What a constant state of fluctuation the whole organic world seems to be in! It is interesting to hear that everywhere the first change apparently is in the proportional numbers of the species. I was much struck with the fact in the upraised shells of Coquimbo, in Chili, as mentioned in my "Geological Observations on South America." Of all the wonders in the world, the progress of Japan, in which you have been aiding, seems to me about the most wonderful. LETTER 296. TO A.R. WALLACE. Down, January 5th 1880. As this note requires no sort of answer, you must allow me to express my lively admiration of your paper in the "Nineteenth Century." (296/1. "Nineteenth Century," January 1880, page 93, "On the Origin of Species and Genera.") You certainly are a master in the difficult art of clear exposition. It is impossible to urge too often that the selection from a single varying individual or of a single varying organ will not suffice. You have worked in capitally Allen's admirable researches. (296/2. J.A. Allen, "On the Mammals and Winter Birds of East Florida, etc." ("Bull. Mus. Comp. Zoolog. Harvard," Volume II.) As usual, you delight to honour me more than I deserve. When I have written about the extreme slowness of Natural Selection (296/3. Mr. Wallace makes a calculation based on Allen's results as to the very short period in which the formation of a race of birds differing 10 to 20 per cent. from the average in length of wing and strength of beak might conceivably be effected. He thinks that the slowness of the action of Natural Selection really depends on the slowness of the changes naturally occurring in the physical conditions, etc.) (in which I hope I may be wrong), I have chiefly had in my mind the effects of intercrossing. I subscribe to almost everything you say excepting the last short sentence. (296/4. The passage in question is as follows: "I have also attempted to show that the causes which have produced the separate species of one genus, of one family, or perhaps of one order, from a common ancestor, are not necessarily the same as those which have produced the separate orders, classes, and sub-kingdoms from more remote common ancestors. That all have been alike produced by 'descent with modification' from a few primitive types, the whole body of evidence clearly indicates; but while individual variation with Natural Selection is proved to be adequate for the production of the former, we have no proof and hardly any evidence that it is adequate to initiate those important divergences of type which characterise the latter." In this passage stress should be laid (as Mr. Wallace points out to us) on the word PROOF. He by no means asserts that the causes which have produced the species of a genus are inadequate to produce greater differences. His object is rather to urge the difference between proof and probability.) LETTER 297. TO J.H. FABRE. (297/1. A letter to M. Fabre is given in "Life and Letters," III., page 220, in which the suggestion is made of rotating the insect before a "homing" experiment occurs.) Down, February 20th, 1880. I thank you for your kind letter, and am delighted that you will try the experiment of rotation. It is very curious that such a belief should be held about cats in your country (297/2. M. Fabre had written from Serignan, Vaucluse: "Parmi la population des paysans de mon village, l'habitude est de faire tourner dans un sac le chat que l'on se propose de porter ailleurs, et dont on veut empecher le retour. J'ignore si cette pratique obtient du succes."), I never heard of anything of the kind in England. I was led, as I believe, to think of the experiment from having read in Wrangel's "Travels in Siberia" (297/3. Admiral Ferdinand Petrovich von Wrangell, "Le Nord de la Siberie, Voyage parmi les Peuplades de la Russie asiatique, etc." Paris, 1843.) of the wonderful power which the Samoyedes possess of keeping their direction in a fog whilst travelling in a tortuous line through broken ice. With respect to cats, I have seen an account that in Belgium there is a society which gives prizes to the cat which can soonest find its way home, and for this purpose they are carried to distant parts of the city. Here would be a capital opportunity for trying rotation. I am extremely glad to hear that your book will probably be translated into English. P.S.--I shall be much pleased to hear the result of your experiments. LETTER 298. TO J.H. FABRE. Down, January 21st, 1881. I am much obliged for your very interesting letter. Your results appear to me highly important, as they eliminate one means by which animals might perhaps recognise direction; and this, from what has been said about savages, and from our own consciousness, seemed the most probable means. If you think it worth while, you can of course mention my name in relation to this subject. Should you succeed in eliminating a sense of the magnetic currents of the earth, you would leave the field of investigation quite open. I suppose that even those who still believe that each species was separately created would admit that certain animals possess some sense by which they perceive direction, and which they use instinctively. On mentioning the subject to my son George, who is a mathematician and knows something about magnetism, he suggested making a very thin needle into a magnet; then breaking it into very short pieces, which would still be magnetic, and fastening one of these pieces with some cement on the thorax of the insect to be experimented on. He believes that such a little magnet, from its close proximity to the nervous system of the insect, would affect it more than would the terrestrial currents. I have received your essay on Halictus (298/1. "Sur les Moeurs et la Parthenogese des Halictes" ("Ann. Sc. Nat." IX., 1879-80).), which I am sure that I shall read with much interest. LETTER 299. TO T.H. HUXLEY. (299/1. On April 9th, 1880, Mr. Huxley lectured at the Royal Institution on "The Coming of Age of the Origin of Species." The lecture was published in "Nature" and in Huxley's "Collected Essays," Volume II., page 227. Darwin's letter to Huxley on the subject is given in "Life and Letters," III., page 240; in Huxley's reply of May 10th ("Life and Letters of T.H. Huxley," II., page 12) he writes: "I hope you do not imagine because I had nothing to say about 'Natural Selection' that I am at all weak of faith on that article...But the first thing seems to me to be to drive the fact of evolution into people's heads; when that is once safe, the rest will come easy.") Down, May 11th, 1880. I had no intention to make you write to me, or expectation of your doing so; but your note has been so far "cheerier" (299/2. "You are the cheeriest letter-writer I know": Huxley to Darwin. See Huxley's "Life," II., page 12.) to me than mine could have been to you, that I must and will write again. I saw your motive for not alluding to Natural Selection, and quite agreed in my mind in its wisdom. But at the same time it occurred to me that you might be giving it up, and that anyhow you could not safely allude to it without various "provisos" too long to give in a lecture. If I think continuously on some half-dozen structures of which we can at present see no use, I can persuade myself that Natural Selection is of quite subordinate importance. On the other hand, when I reflect on the innumerable structures, especially in plants, which twenty years ago would have been called simply "morphological" and useless, and which are now known to be highly important, I can persuade myself that every structure may have been developed through Natural Selection. It is really curious how many out of a list of structures which Bronn enumerated, as not possibly due to Natural Selection because of no functional importance, can now be shown to be highly important. Lobed leaves was, I believe, one case, and only two or three days ago Frank showed me how they act in a manner quite sufficiently important to account for the lobing of any large leaf. I am particularly delighted at what you say about domestic dogs, jackals, and wolves, because from mere indirect evidence I arrived in "Varieties of Domestic Animals" at exactly the same conclusion (299/3. Mr. Darwin's view was that domestic dogs descend from more than one wild species.) with respect to the domestic dogs of Europe and North America. See how important in another way this conclusion is; for no one can doubt that large and small dogs are perfectly fertile together, and produce fertile mongrels; and how well this supports the Pallasian doctrine (299/4. See Letter 80.) that domestication eliminates the sterility almost universal between forms slowly developed in a state of nature. I humbly beg your pardon for bothering you with so long a note; but it is your own fault. Plants are splendid for making one believe in Natural Selection, as will and consciousness are excluded. I have lately been experimenting on such a curious structure for bursting open the seed-coats: I declare one might as well say that a pair of scissors or nutcrackers had been developed through external conditions as the structure in question. (299/5. The peg or heel in Cucurbita: see "Power of Movement in Plants" page 102.) LETTER 300. TO T.H. HUXLEY. Down, November 5th, 1880. On reading over your excellent review (300/1. See "Nature," November 4th, 1880, page 1, a review of Volume I. of the publications of the "Challenger," to which Sir Wyville Thomson contributed a General Introduction.) with the sentence quoted from Sir Wyville Thomson, it seemed to me advisable, considering the nature of the publication, to notice "extreme variation" and another point. Now, will you read the enclosed, and if you approve, post it soon. If you disapprove, throw it in the fire, and thus add one more to the thousand kindnesses which you have done me. Do not write: I shall see result in next week's "Nature." Please observe that in the foul copy I had added a final sentence which I do not at first copy, as it seemed to me inferentially too contemptuous; but I have now pinned it to the back, and you can send it or not, as you think best,--that is, if you think any part worth sending. My request will not cost you much trouble--i.e. to read two pages, for I know that you can decide at once. I heartily enjoyed my talk with you on Sunday morning. P.S.--If my manuscript appears too flat, too contemptuous, too spiteful, or too anything, I earnestly beseech you to throw it into the fire. LETTER 301. CHARLES DARWIN TO THE EDITOR OF "NATURE." (301/1. "Nature," November 11th, 1880, page 32.) Down, November 5th, 1880. Sir Wyville Thomson and Natural Selection. I am sorry to find that Sir Wyville Thomson does not understand the principle of Natural Selection, as explained by Mr. Wallace and myself. If he had done so, he could not have written the following sentence in the Introduction to the Voyage of the "Challenger": "The character of the abyssal fauna refuses to give the least support to the theory which refers the evolution of species to extreme variation guided only by Natural Selection." This is a standard of criticism not uncommonly reached by theologians and metaphysicians, when they write on scientific subjects, but is something new as coming from a naturalist. Professor Huxley demurs to it in the last number of "Nature"; but he does not touch on the expression of extreme variation, nor on that of evolution being guided only by Natural Selection. Can Sir Wyville Thomson name any one who has said that the evolution of species depends only on Natural Selection? As far as concerns myself, I believe that no one has brought forward so many observations on the effects of the use and disuse of parts, as I have done in my "Variation of Animals and Plants under Domestication"; and these observations were made for this special object. I have likewise there adduced a considerable body of facts, showing the direct action of external conditions on organisms; though no doubt since my books were published much has been learnt on this head. If Sir Wyville Thomson were to visit the yard of a breeder, and saw all his cattle or sheep almost absolutely true--that is, closely similar, he would exclaim: "Sir, I see here no extreme variation; nor can I find any support to the belief that you have followed the principle of selection in the breeding of your animals." From what I formerly saw of breeders, I have no doubt that the man thus rebuked would have smiled and said not a word. If he had afterwards told the story to other breeders, I greatly fear that they would have used emphatic but irreverent language about naturalists. (301/2. The following is the passage omitted by the advice of Huxley: see his "Life and Letters," II., page 14:-- "Perhaps it would have been wiser on my part to have remained quite silent, like the breeder; for, as Prof. Sedgwick remarked many years ago, in reference to the poor old Dean of York, who was never weary of inveighing against geologists, a man who talks about what he does not in the least understand, is invulnerable.") LETTER 302. TO G.J. ROMANES. (302/1. Part of this letter has been published in Mr. C. Barber's note on "Graft-Hybrids of the Sugar-Cane," in "The Sugar-Cane," November 1896.) Down, January 1st, 1881. I send the MS., but as far as I can judge by just skimming it, it will be of no use to you. It seems to bear on transitional forms. I feel sure that I have other and better cases, but I cannot remember where to look. I should have written to you in a few days on the following case. The Baron de Villa Franca wrote to me from Brazil about two years ago, describing new varieties of sugar-cane which he had raised by planting two old varieties in apposition. I believe (but my memory is very faulty) that I wrote that I could not believe in such a result, and attributed the new varieties to the soil, etc. I believe that I did not understand what he meant by apposition. Yesterday a packet of MS. arrived from the Brazilian Legation, with a letter in French from Dr. Glass, Director of the Botanic Gardens, describing fully how he first attempted grafting varieties of sugar-cane in various ways, and always failed, and then split stems of two varieties, bound them together and planted them, and then raised some new and very valuable varieties, which, like crossed plants, seem to grow with extra vigour, are constant, and apparently partake of the character of the two varieties. The Baron also sends me an attested copy from a number of Brazilian cultivators of the success of the plan of raising new varieties. I am not sure whether the Brazilian Legation wishes me to return the document, but if I do not hear in three or four days that they must be returned, they shall be sent to you, for they seem to me well deserving your consideration. Perhaps if I had been contented with my hyacinth bulbs being merely bound together without any true adhesion or rather growth together, I should have succeeded like the old Dutchman. There is a deal of superfluous verbiage in the documents, but I have marked with pencil where the important part begins. The attestations are in duplicate. Now, after reading them will you give me your opinion whether the main parts are worthy of publication in "Nature": I am inclined to think so, and it is good to encourage science in out-of-the-way parts of the world. Keep this note till you receive the documents or hear from me. I wonder whether two varieties of wheat could be similarly treated? No, I suppose not--from the want of lateral buds. I was extremely interested by your abstract on suicide. LETTER 303. TO K. SEMPER. Down, February 6th, 1881. Owing to all sorts of work, I have only just now finished reading your "Natural Conditions of Existence." (303/1. Semper's "Natural Conditions of Existence as they affect Animal Life" (International Science Series), 1881.) Although a book of small size, it contains an astonishing amount of matter, and I have been particularly struck with the originality with which you treat so many subjects, and at your scrupulous accuracy. In far the greater number of points I quite follow you in your conclusions, but I differ on some, and I suppose that no two men in the world would fully agree on so many different subjects. I have been interested on so many points, I can hardly say on which most. Perhaps as much on Geographical Distribution as on any other, especially in relation to M. Wagner. (No! no! about parasites interested me even more.) How strange that Wagner should have thought that I meant by struggle for existence, struggle for food. It is curious that he should not have thought of the endless adaptations for the dispersal of seeds and the fertilisation of flowers. Again I was much interested about Branchipus and Artemia. (303/2. The reference is to Schmankewitsch's experiments, page 158: he kept Artemia salina in salt-water, gradually diluted with fresh-water until it became practically free from salt; the crustaceans gradually changed in the course of generations, until they acquired the characters of the genus Branchipus.) When I read imperfectly some years ago the original paper I could not avoid thinking that some special explanation would hereafter be found for so curious a case. I speculated whether a species very liable to repeated and great changes of conditions, might not acquire a fluctuating condition ready to be adapted to either conditions. With respect to Arctic animals being white (page 116 of your book) it might perhaps be worth your looking at what I say from Pallas' and my own observations in the "Descent of Man" (later editions) Chapter VIII., page 229, and Chapter XVIII., page 542. I quite agree with what I gather to be your judgment, viz., that the direct action of the conditions of life on organisms, or the cause of their variability, is the most important of all subjects for the future. For some few years I have been thinking of commencing a set of experiments on plants, for they almost invariably vary when cultivated. I fancy that I see my way with the aid of continued self-fertilisation. But I am too old, and have not strength enough. Nevertheless the hope occasionally revives. Finally let me thank you for the very kind manner in which you often refer to my works, and for the even still kinder manner in which you disagree with me. With cordial thanks for the pleasure and instruction which I have derived from your book, etc. LETTER 304. TO COUNT SAPORTA. Down, February 13th, 1881. I received a week or two ago the work which you and Prof. Marion have been so kind as to send me. (304/1. Probably "L'Evolution du Regne vegetal," I. "Cryptogames," Saporta & Marion, Paris, 1881.) When it arrived I was much engaged, and this must be my excuse for not having sooner thanked you for it, and it will likewise account for my having as yet read only the preface. But I now look forward with great pleasure to reading the whole immediately. If I then have any remarks worth sending, which is not very probable, I will write again. I am greatly pleased to see how boldly you express your belief in evolution, in the preface. I have sometimes thought that some of your countrymen have been a little timid in publishing their belief on this head, and have thus failed in aiding a good cause. LETTER 305. TO R.G. WHITEMAN. Down, May 5th, 1881. In the first edition of the "Origin," after the sentence ending with the words "...insects in the water," I added the following sentence:-- "Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered by Natural Selection more and more aquatic in their structures and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale." (305/1. See Letters 110 and 120.) This sentence was omitted in the subsequent editions, owing to the advice of Prof. Owen, as it was liable to be misinterpreted; but I have always regretted that I followed this advice, for I still think the view quite reasonable. LETTER 306. TO A. HYATT. Down, May 8th, 1881. I am much obliged for your kind gift of "The Genesis, etc." (306/1. "The Genesis of the Tertiary Species of Planorbis," in the "Boston Soc. Nat. Hist. Anniversary Mem." 1880.), which I shall be glad to read, as the case has always seemed to me a very curious one. It is all the kinder in you to send me this book, as I am aware that you think that I have done nothing to advance the good cause of the Descent-theory. (306/2. The above caused me to write a letter expressing a feeling of regret and humiliation, which I hope is still preserved, for certainly such a feeling, caused undoubtedly by my writings, which dealt too exclusively with disagreements upon special points, needed a strong denial. I have used the Darwinian theory in many cases, especially in explaining the preservation of differences; and have denied its application only in the preservation of fixed and hereditary characteristics, which have become essentially homologous similarities. (Note by Prof. Hyatt.)) (306/3. We have ventured to quote the passage from Prof. Hyatt's reply, dated May 23rd, 1881:-- "You would think I was insincere, if I wrote you what I really felt with regard to what you have done for the theory of Descent. Perhaps this essay will lead you to a more correct view than you now have of my estimate, if I can be said to have any claim to make an estimate of your work in this direction. You will not take offence, however, if I tell you that your strongest supporters can hardly give you greater esteem and honour. I have striven to get a just idea of your theory, but no doubt have failed to convey this in my publications as it ought to be done." We find other equally strong and genuine expressions of respect in Prof. Hyatt's letters.) LETTER 307. TO LORD FARRER. (307/1. Mr. Graham's book, the "Creed of Science," is referred to in "Life and Letters," I., page 315, where an interesting letter to the author is printed. With regard to chance, Darwin wrote: "You have expressed my inward conviction, though far more clearly and vividly than I could have done, that the universe is not the result of chance.") Down, August 28th, 1881. I have been much interested by your letter, and am glad that you like Mr. Graham's book...(307/2. In Lord Farrer's letter of August 27th he refers to the old difficulty, in relation to design, of the existence of evil.) Everything which I read now soon goes out of my head, and I had forgotten that he implies that my views explain the universe; but it is a most monstrous exaggeration. The more one thinks the more one feels the hopeless immensity of man's ignorance. Though it does make one proud to see what science has achieved during the last half-century. This has been brought vividly before my mind by having just read most of the proofs of Lubbock's Address for York (307/3. Lord Avebury was President of the British Association in 1881.), in which he will attempt to review the progress of all branches of science for the last fifty years. I entirely agree with what you say about "chance," except in relation to the variations of organic beings having been designed; and I imagine that Mr. Graham must have used "chance" in relation only to purpose in the origination of species. This is the only way I have used the word chance, as I have attempted to explain in the last two pages of my "Variation under Domestication." On the other hand, if we consider the whole universe, the mind refuses to look at it as the outcome of chance--that is, without design or purpose. The whole question seems to me insoluble, for I cannot put much or any faith in the so-called intuitions of the human mind, which have been developed, as I cannot doubt, from such a mind as animals possess; and what would their convictions or intuitions be worth? There are a good many points on which I cannot quite follow Mr. Graham. With respect to your last discussion, I dare say it contains very much truth; but I cannot see, as far as happiness is concerned, that it can apply to the infinite sufferings of animals--not only those of the body, but those of the mind--as when a mother loses her offspring or a male his female. If the view does not apply to animals, will it suffice for man? But you may well complain of this long and badly-expressed note in my dreadfully bad handwriting. The death of my brother Erasmus is a very heavy loss to all of us in this family. He was so kind-hearted and affectionate. Nor have I ever known any one more pleasant. It was always a very great pleasure to talk with him on any subject whatever, and this I shall never do again. The clearness of his mind always seemed to me admirable. He was not, I think, a happy man, and for many years did not value life, though never complaining. I am so glad that he escaped very severe suffering during his last few days. I shall never see such a man again. Forgive me for scribbling this way, my dear Farrer. LETTER 308. TO G.J. ROMANES. (308/1. Romanes had reviewed Roux's "Struggle of Parts in the Organism" in "Nature," September 20th, 1881, page 505. This led to an attack by the Duke of Argyll (October 20th, page 581), followed by a reply by Romanes (October 27th, page 604), a rejoinder by the Duke (November 3rd, page 6), and finally by the letter of Romanes (November 10th, page 29) to which Darwin refers. The Duke's "flourish" is at page 7: "I wish Mr. Darwin's disciples would imitate a little of the dignified reticence of their master. He walks with a patient and a stately step along the paths of conscientious observation, etc., etc.") Down, November 12th, 1881. I must write to say how very much I admire your letter in the last "Nature." I subscribe to every word that you say, and it could not be expressed more clearly or vigorously. After the Duke's last letter and flourish about me I thought it paltry not to say that I agreed with what you had said. But after writing two folio pages I find I could not say what I wished to say without taking up too much space; and what I had written did not please me at all, so I tore it up, and now by all the gods I rejoice that I did so, for you have put the case incomparably better than I had done or could do. Moreover, I hate controversy, and it wastes much time, at least with a man who, like myself, can work for only a short time in a day. How in the world you get through all your work astonishes me. Now do not make me feel guilty by answering this letter, and losing some of your time. You ought not to swear at Roux's book, which has led you into this controversy, for I am sure that your last letter was well worth writing--not that it will produce any effect on the Duke. LETTER 309. TO J. JENNER WEIR. (309/1. On December 27th, 1881, Mr. Jenner Weir wrote to Mr. Darwin: "After some hesitation in lieu of a Christmas card, I venture to give you the return of some observations on mules made in Spain during the last two years...It is a fact that the sire has the prepotency in the offspring, as has been observed by most writers on that subject, including yourself. The mule is more ass-like, and the hinny more horse-like, both in the respective lengths of the ears and the shape of the tail; but one point I have observed which I do not remember to have met with, and that is that the coat of the mule resembles that of its dam the mare, and that of the hinny its dam the ass, so that in this respect the prepotency of the sexes is reversed." The hermaphroditism in lepidoptera, referred to below, is said by Mr. Weir to occur notably in the case of the hybrids of Smerinthus populi-ocellatus.) Down, December 29th, 1881. I thank you for your "Christmas card," and heartily return your good wishes. What you say about the coats of mules is new to me, as is the statement about hermaphroditism in hybrid moths. This latter fact seems to me particularly curious; and to make a very wild hypothesis, I should be inclined to account for it by reversion to the primordial condition of the two sexes being united, for I think it certain that hybridism does lead to reversion. I keep fairly well, but have not much strength, and feel very old. LETTER 310. TO R. MELDOLA. Down, February 2nd, 1882. I am very sorry that I can add nothing to my very brief notice, without reading again Weismann's work and getting up the whole subject by reading my own and other books, and for so much labour I have not strength. I have now been working at other subjects for some years, and when a man grows as old as I am, it is a great wrench to his brain to go back to old and half-forgotten subjects. You would not readily believe how often I am asked questions of all kinds, and quite lately I have had to give up much time to do a work, not at all concerning myself, but which I did not like to refuse. I must, however, somewhere draw the line, or my life will be a misery to me. I have read your preface, and it seems to me excellent. (310/1. "Studies in the Theory of Descent." By A. Weismann. Translated and Edited by Raphael Meldola; with a Prefatory Notice by C. Darwin and a Translator's Preface. See Letter 291.) I am sorry in many ways, including the honour of England as a scientific country, that your translation has as yet sold badly. Does the publisher or do you lose by it? If the publisher, though I shall be sorry for him, yet it is in the way of business; but if you yourself lose by it, I earnestly beg you to allow me to subscribe a trifle, viz., ten guineas, towards the expense of this work, which you have undertaken on public grounds. LETTER 311. TO W. HORSFALL. Down, February 8th, 1882. In the succession of the older Formations the species and genera of trilobites do change, and then they all die out. To any one who believes that geologists know the dawn of life (i.e., formations contemporaneous with the first appearance of living creatures on the earth) no doubt the sudden appearance of perfect trilobites and other organisms in the oldest known life-bearing strata would be fatal to evolution. But I for one, and many others, utterly reject any such belief. Already three or four piles of unconformable strata are known beneath the Cambrian; and these are generally in a crystalline condition, and may once have been charged with organic remains. With regard to animals and plants, the locomotive spores of some algae, furnished with cilia, would have been ranked with animals if it had not been known that they developed into algae. LETTER 312. TO JOHN COLLIER. Down, February 16th, 1882. I must thank you for the gift of your Art Primer, which I have read with much pleasure. Parts were too technical for me who could never draw a line, but I was greatly interested by the whole of the first part. I wish that you could explain why certain curved lines and symmetrical figures give pleasure. But will not your brother artists scorn you for showing yourself so good an evolutionist? Perhaps they will say that allowance must be made for him, as he has allied himself to so dreadful a man as Huxley. This reminds me that I have just been reading the last volume of essays. By good luck I had not read that on Priestley (312/1. "Science and Culture, and other Essays": London, 1881. The fifth Essay is on Joseph Priestley (page 94).), and it strikes me as the most splendid essay which I ever read. That on automatism (312/2. Essay IX. (page 199) is entitled "On the Hypothesis that Animals are Automata, and its history.") is wonderfully interesting: more is the pity, say I, for if I were as well armed as Huxley I would challenge him to a duel on this subject. But I am a deal too wise to do anything of the kind, for he would run me through the body half a dozen times with his sharp and polished rapier before I knew where I was. I did not intend to have scribbled all this nonsense, but only to have thanked you for your present. Everybody whom I have seen and who has seen your picture of me is delighted with it. I shall be proud some day to see myself suspended at the Linnean Society. (312/3. The portrait painted by Mr. Collier hangs in the meeting-room of the Linnean Society.) CHAPTER 1.VI.--GEOGRAPHICAL DISTRIBUTION, 1843-1867. LETTER 313. TO J.D. HOOKER. Down, Tuesday [December 12th, 1843]. I am very much obliged to you for your interesting letter. I have long been very anxious, even for as short a sketch as you have kindly sent me of the botanical geography of the southern hemisphere. I shall be most curious to see your results in detail. From my entire ignorance of Botany, I am sorry to say that I cannot answer any of the questions which you ask me. I think I mention in my "Journal" that I found my old friend the southern beech (I cannot say positively which species), on the mountain-top, in southern parts of Chiloe and at level of sea in lat. 45 deg, in Chonos Archipelago. Would not the southern end of Chiloe make a good division for you? I presume, from the collection of Brydges and Anderson, Chiloe is pretty well-known, and southward begins a terra incognita. I collected a few plants amongst the Chonos Islands. The beech being found here and peat being found here, and general appearance of landscape, connects the Chonos Islands and T. del Fuego. I saw the Alerce (313/1. "Alerse" is the local name of a South American timber, described in Capt. King's "Voyages of the 'Adventure' and 'Beagle,'" page 281, and rather doubtfully identified with Thuja tetragona, Hook. ("Flora Antarctica," page 350.)) on mountains of Chiloe (on the mainland it grows to an enormous size, and I always believed Alerce and Araucaria imbricata to be identical), but I am ashamed to say I absolutely forget all about its appearance. I saw some Juniper-like bush in T. del Fuego, but can tell you no more about it, as I presume that you have seen Capt. King's collection in Mr. Brown's possession, provisionally for the British Museum. I fear you will be much disappointed in my few plants: an ignorant person cannot collect; and I, moreover, lost one, the first, and best set of the Alpine plants. On the other hand, I hope the Galapagos plants (313/2. See "Life and Letters," II., pages 20, 21, for Sir J.D. Hooker's notes on the beginning of his friendship with Mr. Darwin, and for the latter's letter on the Galapagos plants being placed in Hooker's hands.) (judging from Henslow's remarks) will turn out more interesting than you expect. Pray be careful to observe, if I ever mark the individual islands of the Galapagos Islands, for the reasons you will see in my "Journal." Menzies and Cumming were there, and there are some plants (I think Mr. Bentham told me) at the Horticultural Society and at the British Museum. I believe I collected no plants at Ascension, thinking it well-known. Is not the similarity of plants of Kerguelen Land and southern S. America very curious? Is there any instance in the northern hemisphere of plants being similar at such great distances? With thanks for your letter and for your having undertaken my small collection of plants, Believe me, my dear Sir, Yours very truly, C. DARWIN. Do remember my prayer, and write as well for botanical ignoramuses as for great botanists. There is a paper of Carmichael (313/3. "Some Account of the Island of Tristan da Cunha and of its Natural Productions."--"Linn. Soc. Trans." XII., 1818, page 483.) on Tristan d'Acunha, which from the want of general remarks and comparison, I found [torn out] to me a dead letter.--I presume you will include this island in your views of the southern hemisphere. P.S.--I have been looking at my poor miserable attempt at botanical-landscape-remarks, and I see that I state that the species of beech which is least common in T. del Fuego is common in the forest of Central Chiloe. But I will enclose for you this one page of my rough journal. LETTER 314. TO J.D. HOOKER. Down, March 31st (1844). I have been a shameful time in returning your documents, but I have been very busy scientifically, and unscientifically in planting. I have been exceedingly interested in the details about the Galapagos Islands. I need not say that I collected blindly, and did not attempt to make complete series, but just took everything in flower blindly. The flora of the summits and bases of the islands appear wholly different; it may aid you in observing whether the different islands have representative species filling the same places in the economy of nature, to know that I collected plants from the lower and dry region in all the islands, i.e., in the Chatham, Charles, James, and Albemarle (the least on the latter); and that I was able to ascend into the high and damp region only in James and Charles Islands; and in the former I think I got every plant then in flower. Please bear this in mind in comparing the representative species. (You know that Henslow has described a new Opuntia from the Galapagos.) Your observations on the distribution of large mundane genera have interested me much; but that was not the precise point which I was curious to ascertain; it has no necessary relation to size of genus (though perhaps your statements will show that it has). It was merely this: suppose a genus with ten or more species, inhabiting the ten main botanical regions, should you expect that all or most of these ten species would have wide ranges (i.e. were found in most parts) in their respective countries? (314/1. This point is discussed in a letter in "Life and Letters," Volume II., page 25, but not, we think in the "Origin"; for letters on large genera containing many varieties see "Life and Letters," Volume II., pages 102-7, also in the "Origin," Edition I., page 53, Edition VI., page 44. In a letter of April 5th, 1844, Sir J.D. Hooker gave his opinion: "On the whole I believe that many individual representative species of large genera have wide ranges, but I do not consider the fact as one of great value, because the proportion of such species having a wide range is not large compared with other representative species of the same genus whose limits are confined." It may be noted that in large genera the species often have small ranges ("Origin," Edition VI., page 45), and large genera are more commonly wide-ranging than the reverse.) To give an example, the genus Felis is found in every country except Australia, and the individual species generally range over thousands of miles in their respective countries; on the other hand, no genus of monkey ranges over so large a part of the world, and the individual species in their respective countries seldom range over wide spaces. I suspect (but am not sure) that in the genus Mus (the most mundane genus of all mammifers) the individual species have not wide ranges, which is opposed to my query. I fancy, from a paper by Don, that some genera of grasses (i.e. Juncus or Juncaceae) are widely diffused over the world, and certainly many of their species have very wide ranges--in short, it seems that my question is whether there is any relation between the ranges of genera and of individual species, without any relation to the size of the genera. It is evident a genus might be widely diffused in two ways: 1st, by many different species, each with restricted ranges; and 2nd, by many or few species with wide ranges. Any light which you could throw on this I should be very much obliged for. Thank you most kindly, also, for your offer in a former letter to consider any other points; and at some future day I shall be most grateful for a little assistance, but I will not be unmerciful. Swainson has remarked (and Westwood contradicted) that typical genera have wide ranges: Waterhouse (without knowing these previous remarkers) made to me the same observation: I feel a laudable doubt and disinclination to believe any statement of Swainson; but now Waterhouse remarks it, I am curious on the point. There is, however, so much vague in the meaning of "typical forms," and no little ambiguity in the mere assertion of "wide ranges" (for zoologists seldom go into strict and disagreeable arithmetic, like you botanists so wisely do) that I feel very doubtful, though some considerations tempt me to believe in this remark. Here again, if you can throw any light, I shall be much obliged. After your kind remarks I will not apologise for boring you with my vague queries and remarks. LETTER 315. TO J.D. HOOKER. Down, December 25th [1844]. Happy Christmas to you. (315/1. The following letter refers to notes by Sir J.D. Hooker which we have not seen. Though we are therefore unable to make clear many points referred to, the letter seems to us on the whole so interesting that it is printed with the omission of only one unimportant sentence. The subjects dealt with in the letter are those which were occupying Hooker's attention in relation to his "Flora Antarctica" (1844).) I must thank you once again for all your documents, which have interested me very greatly and surprised me. I found it very difficult to charge my head with all your tabulated results, but this I perfectly well know is in main part due to that head not being a botanical one, aided by the tables being in MS.; I think, however, to an ignoramus, they might be made clearer; but pray mind, that this is very different from saying that I think botanists ought to arrange their highest results for non-botanists to understand easily. I will tell you how, for my individual self, I should like to see the results worked out, and then you can judge, whether this be advisable for the botanical world. Looking at the globe, the Auckland and Campbell I., New Zealand, and Van Diemen's Land so evidently are geographically related, that I should wish, before any comparison was made with far more distant countries, to understand their floras, in relation to each other; and the southern ones to the northern temperate hemisphere, which I presume is to every one an almost involuntary standard of comparison. To understand the relation of the floras of these islands, I should like to see the group divided into a northern and southern half, and to know how many species exist in the latter-- 1. Belonging to genera confined to Australia, Van Diemen's Land and north New Zealand. 2. Belonging to genera found only on the mountains of Australia, Van Diemen's Land, and north New Zealand. 3. Belonging to genera of distribution in many parts of the world (i.e., which tell no particular story). 4. Belonging to genera found in the northern hemisphere and not in the tropics; or only on mountains in the tropics. I daresay all this (as far as present materials serve) could be extracted from your tables, as they stand; but to any one not familiar with the names of plants, this would be difficult. I felt particularly the want of not knowing which of the genera are found in the lowland tropics, in understanding the relation of the Antarctic with the Arctic floras. If the Fuegian flora was treated in the analogous way (and this would incidentally show how far the Cordillera are a high-road of genera), I should then be prepared far more easily and satisfactorily to understand the relations of Fuegia with the Auckland Islands, and consequently with the mountains of Van Diemen's Land. Moreover, the marvellous facts of their intimate botanical relation (between Fuegia and the Auckland Islands, etc.) would stand out more prominently, after the Auckland Islands had been first treated of under the purely geographical relation of position. A triple division such as yours would lead me to suppose that the three places were somewhat equally distant, and not so greatly different in size: the relation of Van Diemen's Land seems so comparatively small, and that relation being in its alpine plants, makes me feel that it ought only to be treated of as a subdivision of the large group, including Auckland, Campbell, New Zealand... I think a list of the genera, common to Fuegia on the one hand and on the other to Campbell, etc., and to the mountains of Van Diemen's Land or New Zealand (but not found in the lowland temperate, and southern tropical parts of South America and Australia, or New Zealand), would prominently bring out, at the same time, the relation between these Antarctic points one with another, and with the northern or Arctic regions. In Article III. is it meant to be expressed, or might it not be understood by this article, that the similarity of the distant points in the Antarctic regions was as close as between distant points in the Arctic regions? I gather this is not so. You speak of the southern points of America and Australia, etc., being "materially approximated," and this closer proximity being correlative with a greater similarity of their plants: I find on the globe, that Van Diemen's Land and Fuegia are only about one-fifth nearer than the whole distance between Port Jackson and Concepcion in Chile; and again, that Campbell Island and Fuegia are only one-fifth nearer than the east point of North New Zealand and Concepcion. Now do you think in such immense distances, both over open oceans, that one-fifth less distance, say 4,000 miles instead of 5,000, can explain or throw much light on a material difference in the degree of similarity in the floras of the two regions? I trust you will work out the New Zealand flora, as you have commenced at end of letter: is it not quite an original plan? and is it not very surprising that New Zealand, so much nearer to Australia than South America, should have an intermediate flora? I had fancied that nearly all the species there were peculiar to it. I cannot but think you make one gratuitous difficulty in ascertaining whether New Zealand ought to be classed by itself, or with Australia or South America--namely, when you seem (bottom of page 7 of your letter) to say that genera in common indicate only that the external circumstances for their life are suitable and similar. (315/2. On December 30th, 1844, Sir J.D. Hooker replied, "Nothing was further from my intention than to have written anything which would lead one to suppose that genera common to two places indicate a similarity in the external circumstances under which they are developed, though I see I have given you excellent grounds for supposing that such were my opinions.") Surely, cannot an overwhelming mass of facts be brought against such a proposition? Distant parts of Australia possess quite distinct species of marsupials, but surely this fact of their having the same marsupial genera is the strongest tie and plainest mark of an original (so-called) creative affinity over the whole of Australia; no one, now, will (or ought) to say that the different parts of Australia have something in their external conditions in common, causing them to be pre-eminently suitable to marsupials; and so on in a thousand instances. Though each species, and consequently genus, must be adapted to its country, surely adaptation is manifestly not the governing law in geographical distribution. Is this not so? and if I understand you rightly, you lessen your own means of comparison--attributing the presence of the same genera to similarity of conditions. You will groan over my very full compliance with your request to write all I could on your tables, and I have done it with a vengeance: I can hardly say how valuable I must think your results will be, when worked out, as far as the present knowledge and collections serve. Now for some miscellaneous remarks on your letter: thanks for the offer to let me see specimens of boulders from Cockburn Island; but I care only for boulders, as an indication of former climate: perhaps Ross will give some information... Watson's paper on the Azores (315/3. H.C. Watson, "London Journal of Botany," 1843-44.) has surprised me much; do you not think it odd, the fewness of peculiar species, and their rarity on the alpine heights? I wish he had tabulated his results; could you not suggest to him to draw up a paper of such results, comparing these Islands with Madeira? surely does not Madeira abound with peculiar forms? A discussion on the relations of the floras, especially the alpine ones, of Azores, Madeira, and Canary Islands, would be, I should think, of general interest. How curious, the several doubtful species, which are referred to by Watson, at the end of his paper; just as happens with birds at the Galapagos...Any time that you can put me in the way of reading about alpine floras, I shall feel it as the greatest kindness. I grieve there is no better authority for Bourbon, than that stupid Bory: I presume his remark that plants, on isolated volcanic islands are polymorphous (i.e., I suppose, variable?) is quite gratuitous. Farewell, my dear Hooker. This letter is infamously unclear, and I fear can be of no use, except giving you the impression of a botanical ignoramus. LETTER 316. TO J.D. HOOKER. Down, March 19th [1845]. ...I was very glad to hear Humboldt's views on migrations and double creations. It is very presumptuous, but I feel sure that though one cannot prove extensive migration, the leading considerations, proper to the subject, are omitted, and I will venture to say even by Humboldt. I should like some time to put the case, like a lawyer, for your consideration, in the point of view under which, I think, it ought to be viewed. The conclusion which I come to is, that we cannot pretend, with our present knowledge, to put any limit to the possible, and even probable, migration of plants. If you can show that many of the Fuegian plants, common to Europe, are found in intermediate points, it will be a grand argument in favour of the actuality of migration; but not finding them will not, in my eyes, much diminish the probability of their having thus migrated. My pen always runs away, in writing to you; and a most unsteady, vilely bad pace it goes. What would I not give to write simple English, without having to rewrite and rewrite every sentence. LETTER 317. TO J.D. HOOKER. Friday [June 29th, 1845]. I have been an ungrateful dog for not having answered your letter sooner, but I have been so hard at work correcting proofs (317/1. The second edition of the "Journal."), together with some unwellness, that I have not had one quarter of an hour to spare. I finally corrected the first third of the old volume, which will appear on July 1st. I hope and think I have somewhat improved it. Very many thanks for your remarks; some of them came too late to make me put some of my remarks more cautiously. I feel, however, still inclined to abide by my evaporation notion to account for the clouds of steam, which rise from the wooded valleys after rain. Again, I am so obstinate that I should require very good evidence to make me believe that there are two species of Polyborus (317/2. Polyborus Novae Zelandiae, a carrion hawk mentioned as very common in the Falklands.) in the Falkland Islands. Do the Gauchos there admit it? Much as I talked to them, they never alluded to such a fact. In the Zoology I have discussed the sexual and immature plumage, which differ much. I return the enclosed agreeable letter with many thanks. I am extremely glad of the plants collected at St. Paul's, and shall be particularly curious whenever they arrive to hear what they are. I dined the other day at Sir J. Lubbock's, and met R. Brown, and we had much laudatory talk about you. He spoke very nicely about your motives in now going to Edinburgh. He did not seem to know, and was much surprised at what I stated (I believe correctly) on the close relation between the Kerguelen and T. del Fuego floras. Forbes is doing apparently very good work about the introduction and distribution of plants. He has forestalled me in what I had hoped would have been an interesting discussion--viz., on the relation between the present alpine and Arctic floras, with connection to the last change of climate from Arctic to temperate, when the then Arctic lowland plants must have been driven up the mountains. (317/3. Forbes' Essay "On the Connection between the Distribution of the Existing Fauna and Flora of the British Isles and the Geological Changes which have affected their Area," was published in 1846. See note, Letter 20.) I am much pleased to hear of the pleasant reception you received at Edinburgh. (317/4. Sir J.D. Hooker was a candidate for the Chair of Botany at Edinburgh. See "Life and Letters," I., pages 335, 342.) I hope your impressions will continue agreeable; my associations with auld Reekie are very friendly. Do you ever see Dr. Coldstream? If you do, would you give him my kind remembrances? You ask about amber. I believe all the species are extinct (i.e. without the amber has been doctored), and certainly the greater number are. (317/5. For an account of plants in amber see Goeppert and Berendt, "Der Bernstein und die in ihm befindlichen Pflanzenreste der Vorwelt," Berlin, 1845; Goeppert, "Coniferen des Bernstein," Danzig, 1883; Conwentz, "Monographie der Baltischen Bernsteinbaume," Danzig, 1890.) If you have any other corrections ready, will you send them soon, for I shall go to press with second Part in less than a week. I have been so busy that I have not yet begun d'Urville, and have read only first chapter of Canary Islands! I am most particularly obliged to you for having lent me the latter, for I know not where else I could have ever borrowed it. There is the "Kosmos" to read, and Lyell's "Travels in North America." It is awful to think of how much there is to read. What makes H. Watson a renegade? I had a talk with Captain Beaufort the other day, and he charged me to keep a book and enter anything which occurred to me, which deserved examination or collection in any part of the world, and he would sooner or later get it in the instructions to some ship. If anything occurs to you let me hear, for in the course of a month or two I must write out something. I mean to urge collections of all kinds on any isolated islands. I suspect that there are several in the northern half of the Pacific, which have never been visited by a collector. This is a dull, untidy letter. Farewell. As you care so much for insular floras, are you aware that I collected all in flower on the Abrolhos Islands? but they are very near the coast of Brazil. Nevertheless, I think they ought to be just looked at, under a geographical point of view. LETTER 318. TO J.D. HOOKER. Down, November [1845]. I have just got as far as Lycopodium in your Flora, and, in truth, cannot say enough how much I have been interested in all your scattered remarks. I am delighted to have in print many of the statements which you made in your letters to me, when we were discussing some of the geographical points. I can never cease marvelling at the similarity of the Antarctic floras: it is wonderful. I hope you will tabulate all your results, and put prominently what you allude to (and what is pre-eminently wanted by non-botanists like myself), which of the genera are, and which not, found in the lowland or in the highland Tropics, as far as known. Out of the very many new observations to me, nothing has surprised me more than the absence of Alpine floras in the S[outh] Islands. (318/1. See "Flora Antarctica," I., page 79, where the author says that "in the South...on ascending the mountains, few or no new forms occur." With regard to the Sandwich Islands, Sir Joseph wrote (page 75) that "though the volcanic islands of the Sandwich group attain a greater elevation than this [10,000 feet], there is no such development of new species at the upper level." More recent statements to the same effect occur in Grisebach, "Vegetation der Erde," Volume II., page 530. See also Wallace, "Island Life," page 307.) It strikes me as most inexplicable. Do you feel sure about the similar absence in the Sandwich group? Is it not opposed quite to the case of Teneriffe and Madeira, and Mediterranean Islands? I had fancied that T. del Fuego had possessed a large alpine flora! I should much like to know whether the climate of north New Zealand is much more insular than Tasmania. I should doubt it from general appearance of places, and yet I presume the flora of the former is far more scanty than of Tasmania. Do tell me what you think on this point. I have also been particularly interested by all your remarks on variation, affinities, etc.: in short, your book has been to me a most valuable one, and I must have purchased it had you not most kindly given it, and so rendered it even far more valuable to me. When you compare a species to another, you sometimes do not mention the station of the latter (it being, I presume, well-known), but to non-botanists such words of explanation would add greatly to the interest--not that non-botanists have any claim at all for such explanations in professedly botanical works. There is one expression which you botanists often use (though, I think, not you individually often), which puts me in a passion--viz., calling polleniferous flowers "sterile," as non-seed-bearing. (318/2. See Letter 16.) Are the plates from your own drawings? They strike me as excellent. So now you have had my presumptuous commendations on your great work. LETTER 319. TO J.D. HOOKER. Down, Friday [1845-6]. It is quite curious how our opinions agree about Forbes' views. (319/1. See Letter 20.) I was very glad to have your last letter, which was even more valuable to me than most of yours are, and that is saying, I assure you, a great deal. I had written to Forbes to object about the Azores (319/2. Edward Forbes supposed that the Azores, the Madeiras, and Canaries "are the last remaining fragments" of a continent which once connected them with Western Europe and Northern Spain. Lyell's "Principles," Edition XI., Volume II., page 410. See Forbes, op. cit.) on the same grounds as you had, and he made some answer, which partially satisfied me, but really I am so stupid I cannot remember it. He insisted strongly on the fewness of the species absolutely peculiar to the Azores--most of the non-European species being common to Madeira. I had thought that a good sprinkling were absolutely peculiar. Till I saw him last Wednesday I thought he had not a leg to stand on in his geology about his post-Miocene land; and his reasons, upon reflection, seem rather weak: the main one is that there are no deposits (more recent than the Miocene age) on the Miocene strata of Malta, etc., but I feel pretty sure that this cannot be trusted as evidence that Malta must have been above water during all the post-Miocene period. He had one other reason, to my mind still less trustworthy. I had also written to Forbes, before your letter, objecting to the Sargassum (319/3. Edward Forbes supposed that the Sargassum or Gulf-weed represents the littoral sea-weeds of a now submerged continent. "Mem. Geol. Survey Great Britain," Volume I., 1846, page 349. See Lyell's "Principles," II., page 396, Edition XI.), but apparently on wrong grounds, for I could see no reason, on the common view of absolute creations, why one Fucus should not have been created for the ocean, as well as several Confervae for the same end. It is really a pity that Forbes is quite so speculative: he will injure his reputation, anyhow, on the Continent; and thus will do less good. I find this is the opinion of Falconer, who was with us on Sunday, and was extremely agreeable. It is wonderful how much heterogeneous information he has about all sorts of things. I the more regret Forbes cannot more satisfactorily prove his views, as I heartily wish they were established, and to a limited extent I fully believe they are true; but his boldness is astounding. Do I understand your letter right, that West Africa (319/4. This is of course a misunderstanding.) and Java belong to the same botanical region--i.e., that they have many non-littoral species in common? If so, it is a sickening fact: think of the distance with the Indian Ocean interposed! Do some time answer me this. With respect to polymorphism, which you have been so very kind as to give me so much information on, I am quite convinced it must be given up in the sense you have discussed it in; but from such cases as the Galapagos birds and from hypothetical notions on variation, I should be very glad to know whether it must be given up in a slightly different point of view; that is, whether the peculiar insular species are generally well and strongly distinguishable from the species on the nearest continent (when there is a continent near); the Galapagos, Canary Islands, and Madeira ought to answer this. I should have hypothetically expected that a good many species would have been fine ones, like some of the Galapagos birds, and still more so on the different islands of such groups. I am going to ask you some questions, but I should really sometimes almost be glad if you did not answer me for a long time, or not at all, for in honest truth I am often ashamed at, and marvel at, your kindness in writing such long letters to me. So I beg you to mind, never to write to me when it bores you. Do you know "Elements de Teratologie (on monsters, I believe) Vegetale," par A. Moquin Tandon"? (319/5. Paris, 1841.) Is it a good book, and will it treat on hereditary malconformations or varieties? I have almost finished the tremendous task of 850 pages of A. St. Hilaire's Lectures (319/6. "Lecons de Botanique," 1841.), which you set me, and very glad I am that you told me to read it, for I have been much interested with parts. Certain expressions which run through the whole work put me in a passion: thus I take, at hazard, "la plante n'etait pas tout a fait ASSEZ AFFAIBLIE pour produire de veritables carpelles." Every organ or part concerned in reproduction--that highest end of all lower organisms--is, according to this man, produced by a lesser or greater degree of "affaiblissement"; and if that is not an AFFAIBLISSEMENT of language, I don't know what is. I have used an expression here, which leads me to ask another question: on what sort of grounds do botanists make one family of plants higher than another? I can see that the simplest cryptogamic are lowest, and I suppose, from their relations, the monocotyledonous come next; but how in the different families of the dicotyledons? The point seems to me equally obscure in many races of animals, and I know not how to tell whether a bee or cicindela is highest. (319/7. On use of terms "high" and "low" see Letters 36 and 70.) I see Aug. Hilaire uses a multiplicity of parts--several circles of stamens, etc.--as evidence of the highness of the Ranunculaceae; now Owen has truly, as I believe, used the same argument to show the lowness of some animals, and has established the proposition, that the fewer the number of any organ, as legs or wings or teeth, by which the same end is gained, the higher the animal. One other question. Hilaire says (page 572) that "chez une foule de plantes c'est dans le bouton," that impregnation takes place. He instances only Goodenia (319/8. For letters on this point, see Index s.v. Goodenia.), and Falconer cannot recollect any cases. Do you know any of this "foule" of plants? From reasons, little better than hypothetical, I greatly misdoubt the accuracy of this, presumptuous as it is; that plants shed their pollen in the bud is, of course, quite a different story. Can you illuminate me? Henslow will send the Galapagos scraps to you. I direct this to Kew, as I suppose, after your sister's marriage (on which I beg to send you my congratulations), you will return home. There are great fears that Falconer will have to go out to India--this will be a grievous loss to Palaeontology. LETTER 320. TO J.D. HOOKER. Down, April 10th [1846]. I was much pleased to see and sign your certificate for the Geolog[ical Society]; we shall thus occasionally, I hope, meet. (320/1. Sir Joseph was elected a Fellow of the Geological Society in 1846.) I have been an ungrateful dog not to have thanked you before this for the cake and books. The children and their betters pronounced the former excellent, and Annie wanted to know whether it was the gentleman "what played with us so." I wish we were at a more reasonable distance, that Emma and myself could have called on Lady Hooker with our congratulations on this occasion. It was very good of you to put in both numbers of the "Hort. Journal." I think Dean Herbert's article well worth reading. I have been so extravagant as to order M[oquin] Tandon (320/2. Probably "Elements de Teratologie Vegetale": Paris, 1841.), for though I have not found, as yet, anything particularly novel or striking, yet I found that I wished to score a good many passages so as to re-read them at some future time, and hence have ordered the book. Consequently I hope soon to send back your books. I have sent off the Ascension plants through Bunsen to Ehrenberg. There was much in your last long letter which interested me much; and I am particularly glad that you are going to attend to polymorphism in our last and incorrect sense in your works; I see that it must be most difficult to take any sort of constant limit for the amount of possible variation. How heartily I do wish that all your works were out and complete; so that I could quietly think over them. I fear the Pacific Islands must be far distant in futurity. I fear, indeed, that Forbes is going rather too quickly ahead; but we shall soon see all his grounds, as I hear he is now correcting the press on this subject; he has plenty of people who attack him; I see Falconer never loses a chance, and it is wonderful how well Forbes stands it. What a very striking fact is the botanical relation between Africa and Java; as you now state it, I am pleased rather than disgusted, for it accords capitally with the distribution of the mammifers (320/3. See Wallace, "Geogr. Distribution," Volume I., page 263, on the "special Oriental or even Malayan element" in the West African mammals and birds.): only that I judge from your letters that the Cape differs even more markedly than I had thought, from the rest of Africa, and much more than the mammifers do. I am surprised to find how well mammifers and plants seem to accord in their general distribution. With respect to my strong objection to Aug. St. Hilaire's language on AFFAIBLISSEMENT (320/4. This refers to his "Lecons de Botanique (Morphologie Vegetale)," 1841. Saint-Hilaire often explains morphological differences as due to differences in vigour. See Letter 319.), it is perhaps hardly rational, and yet he confesses that some of the most vigorous plants in nature have some of their organs struck with this weakness--he does not pretend, of course, that they were ever otherwise in former generations--or that a more vigorously growing plant produces organs less weakened, and thus fails in producing its typical structure. In a plant in a state of nature, does cutting off the sap tend to produce flower-buds? I know it does in trees in orchards. Owen has been doing some grand work in the morphology of the vertebrata: your arm and hand are parts of your head, or rather the processes (i.e. modified ribs) of the occipital vertebra! He gave me a grand lecture on a cod's head. By the way, would it not strike you as monstrous, if in speaking of the minute and lessening jaws, palpi, etc., of an insect or crustacean, any one were to say they were produced by the affaiblissement of the less important but larger organs of locomotion. I see from your letter (though I do not suppose it is worth referring to the subject) that I could not have expressed what I meant when I allowed you to infer that Owen's rule of single organs being of a higher order than multiple organs applied only to locomotive, etc.; it applies to every the most important organ. I do not doubt that he would say the placentata having single wombs, whilst the marsupiata have double ones, is an instance of this law. I believe, however, in most instances where one organ, as a nervous centre or heart, takes the places of several, it rises in complexity; but it strikes me as really odd, seeing in this instance eminent botanists and zoologists starting from reverse grounds. Pray kindly bear in mind about impregnation in bud: I have never (for some years having been on the look-out) heard of an instance: I have long wished to know how it was in Subularia, or some such name, which grows on the bottom of Scotch lakes, and likewise in a grassy plant, which lives in brackish water, I quite forget name, near Thames; elder botanists doubted whether it was a Phanerogam. When we meet I will tell you why I doubt this bud-impregnation. We are at present in a state of utmost confusion, as we have pulled all our offices down and are going to rebuild and alter them. I am personally in a state of utmost confusion also, for my cruel wife has persuaded me to leave off snuff for a month; and I am most lethargic, stupid, and melancholy in consequence. Farewell, my dear Hooker. Ever yours. LETTER 321. TO J.D. HOOKER. Down, April 19th [1855]. Thank you for your list of R.S. candidates, which will be very useful to me. I have thought a good deal about my salting experiments (321/1. For an account of Darwin's experiments on the effect of salt water on the germination of seeds, see "Life and Letters," II., page 54. In April he wrote to the "Gardeners' Chronicle" asking for information, and his results were published in the same journal, May 26th and November 24th, 1855; also in the "Linn. Soc. Journal," 1857.), and really think they are worth pursuing to a certain extent; but I hardly see the use (at least, the use equivalent to the enormous labour) of trying the experiment on the immense scale suggested by you. I should think a few seeds of the leading orders, or a few seeds of each of the classes mentioned by you, with albumen of different kinds would suffice to show the possibility of considerable sea-transportal. To tell whether any particular insular flora had thus been transported would require that each species should be examined. Will you look through these printed lists, and if you can, mark with red cross such as you would suggest? In truth, I fear I impose far more on your great kindness, my dear Hooker, than I have any claim; but you offered this, for I never thought of asking you for more than a suggestion. I do not think I could manage more than forty or fifty kinds at a time, for the water, I find, must be renewed every other day, as it gets to smell horribly: and I do not think your plan good of little packets of cambric, as this entangles so much air. I shall keep the great receptacle with salt water with the forty or fifty little bottles, partly open, immersed in it, in the cellar for uniform temperature. I must plant out of doors, as I have no greenhouse. I told you I had inserted notice in the "Gardeners' Chronicle," and to-day I have heard from Berkeley that he has already sent an assortment of seeds to Margate for some friend to put in salt water; so I suppose he thinks the experiment worth trying, as he has thus so very promptly taken it into his own hands. (321/2. Rev. M.J. Berkeley published on the subject in the "Gardeners' Chronicle," September 1st, 1855.) Reading this over, it sounds as if I were offended!!! which I need not say is not so. (321/3. Added afterwards between the lines.) I may just mention that the seeds mentioned in my former note have all germinated after fourteen days' immersion, except the cabbages all dead, and the radishes have had their germination delayed and several I think dead; cress still all most vigorous. French spinach, oats, barley, canary-seed, borage, beet have germinated after seven days' immersion. It is quite surprising that the radishes should have grown, for the salt water was putrid to an extent which I could not have thought credible had I not smelt it myself, as was the water with the cabbage-seed. LETTER 322. TO J.D. HOOKER. Down, June 10th [1855]. If being thoroughly interested with your letters makes me worthy of them, I am very worthy. I have raised some seedling Sensitive Plants, but if you can READILY spare me a moderately sized plant, I shall be glad of it. You encourage me so, that I will slowly go on salting seeds. I have not, I see, explained myself, to let you suppose that I objected to such cases as the former union of England and the Continent; I look at this case as proved by animals, etc., etc.; and, indeed, it would be an astounding fact if the land had kept so steady as that they had not been united, with Snowdon elevated 1,300 feet in recent times, etc., etc. It is only against the former union with the oceanic volcanic islands that I am vehement. (322/1. See "Life and Letters," Volume II., pages 72, 74, 80, 109.) What a perplexing case New Zealand does seem: is not the absence of Leguminosae, etc., etc., FULLY as much opposed to continental connexion as to any other theory? What a curious fact you state about distribution and lowness going together. The presence of a frog in New Zealand seems to me a strongish fact for continental connexion, for I assume that sea water would kill spawn, but I shall try. The spawn, I find, will live about ten days out of water, but I do not think it could possibly stick to a bird. What you say about no one realising creation strikes me as very true; but I think and hope that there is nearly as much difference between trying to find out whether species of a genus have had a common ancestor and concerning oneself with the first origin of life, as between making out the laws of chemical attraction and the first origin of matter. I thought that Gray's letter had come open to you, and that you had read it: you will see what I asked--viz., for habitats of the alpine plants, but I presume there will be nothing new to you. Please return both. How pleasantly Gray takes my request, and I think I shall have done a good turn if I make him write a paper on geographical distribution of plants of United States. I have written him a very long letter, telling him some of the points about which I should feel curious. But on my life it is sublimely ridiculous, my making suggestions to such a man. I cannot help thinking that what you say about low plants being widely distributed and standing injurious conditions better than higher ones (but is not this most difficult to show?) is equally favourable to sea-transport, to continental connexions, and all other means. Pray do not suppose that I fancy that if I could show that nearly all seeds could stand an almost indefinite period of immersion in sea-water, that I have done more than one EXTREMELY SMALL step in solving the problem of distribution, for I can quite appreciate the importance of the fact you point out; and then the directions of currents in past and present times have to be considered!! I shall be very curious to hear Berkeley's results in the salting line. With respect to geological changes, I ought to be one of the last men to undervalue them after my map of coral islands, and after what I have seen of elevation on coast of America. Farewell. I hope my letters do not bother you. Again, and for the last time, I say that I should be extremely vexed if ever you write to me against the grain or when tired. LETTER 323. TO J.S HENSLOW. Down, July 2nd [1855]. Very many thanks for all you have done, and so very kindly promise to do for me. Will you make a present to each of the little girls (if not too big and grandiose) of six pence (for which I send stamps), who are going to collect seeds for me: viz., Lychnis, white, red, and flesh-colour (if such occur). ...Will you be so kind as to look at them before sent, just to see positively that they are correct, for remember how ignorant botanically I am. Do you see the "Gardeners' Chronicle," and did you notice some little experiments of mine on salting seeds? Celery and onion seed have come up after eighty-five days' immersion in the salt water, which seems to me surprising, and I think throws some light on the wide dispersion of certain plants. Now, it has occurred to me that it would be an interesting way of testing the probability of sea-transportal of seeds, to make a list of all the European plants found in the Azores--a very oceanic archipelago--collect the seeds, and try if they would stand a pretty long immersion. Do you think the most able of your little girls would like to collect for me a packet of seeds of such Azorean plants as grow near Hitcham, I paying, say 3 pence for each packet: it would put a few shillings into their pockets, and would be an enormous advantage to me, for I grudge the time to collect the seeds, more especially as I have to learn the plants! The experiment seems to me worth trying: what do you think? Should you object offering for me this reward or payment to your little girls? You would have to select the most conscientious ones, that I might not get wrong seeds. I have just been comparing the lists, and I suspect you would not have very many of the Azorean plants. You have, however, Ranunculus repens, Ranunculus parviflorus, Papaver rhoeas,? Papaver dubium,? Chelidonium majus,? Fumaria officinalis.? All these are Azorean plants. With respect to cultivating plants, I mean to begin on very few, for I may find it too troublesome. I have already had for some months primroses and cowslips, strongly manured with guano, and with flowers picked off, and one cowslip made to grow in shade; and next spring I shall collect seed. I think you have quite misunderstood me in regard to my object in getting you to mark in accompanying list with (x) all the "close species" (323/1. See Letter 279.) i.e., such as you do not think to be varieties, but which nevertheless are very closely allied; it has nothing whatever to do with their cultivation, but I cannot tell you [my] object, as it might unconsciously influence you in marking them. Will you draw your pencil right through all the names of those (few) species, of which you may know nothing. Afterwards, when done, I will tell you my object--not that it is worth telling, though I myself am very curious on the subject. I know and can perceive that the definition of "close species" is very vague, and therefore I should not care for the list being marked by any one, except by such as yourself. Forgive this long letter. I thank you heartily for all your assistance. My dear old Master, Yours affectionately, C. Darwin. Perhaps 3 pence would be hardly enough, and if the number of kinds does not turn out very great it shall be 6 pence per packet. LETTER 324. ASA GRAY TO CHARLES DARWIN. (324/1. In reply to Darwin's letter, June 8th, 1855, given in "Life and Letters," II., page 61.) Harvard University, Cambridge, U.S., June 30th, 1855. Your long letter of the 8th inst. is full of interest to me, and I shall follow out your hints as far as I can. I rejoice in furnishing facts to others to work up in their bearing on general questions, and feel it the more my duty to do so inasmuch as from preoccupation of mind and time and want of experience I am unable to contribute direct original investigations of the sort to the advancement of science. Your request at the close of your letter, which you have such needless hesitation in making, is just the sort of one which it is easy for me to reply to, as it lies directly in my way. It would probably pass out of my mind, however, at the time you propose, so I will attend to it at once, to fill up the intervals of time left me while attending to one or two pupils. So I take some unbound sheets of a copy of the "Manual," and mark off the "close species" by connecting them with a bracket. Those thus connected, some of them, I should in revision unite under one, many more Dr. Hooker would unite, and for the rest it would not be extraordinary if, in any case, the discovery of intermediate forms compelled their union. As I have noted on the blank page of the sheets I send you (through Sir William Hooker), I suppose that if we extended the area, say to that of our flora of North America, we should find that the proportion of "close species" to the whole flora increased considerably. But here I speak at a venture. Some day I will test it for a few families. If you take for comparison with what I send you, the "British Flora," or Koch's "Flora Germanica," or Godron's "Flora of France," and mark the "close species" on the same principle, you will doubtless find a much greater number. Of course you will not infer from this that the two floras differ in this respect; since the difference is probably owing to the facts that (1) there have not been so many observers here bent upon detecting differences; and (2) our species, thanks mostly to Dr. Torrey and myself, have been more thoroughly castigated. What stands for one species in the "Manual" would figure in almost any European flora as two, three, or more, in a very considerable number of cases. In boldly reducing nominal species J. Hooker is doing a good work; but his vocation--like that of any other reformer--exposes him to temptations and dangers. Because you have shown that a and b are so connected by intermediate forms that we cannot do otherwise than regard them as variations of one species, we may not conclude that c and d, differing much in the same way and to the same degree, are of one species, before an equal amount of evidence is actually obtained. That is, when two sets of individuals exhibit any grave differences, the burden of proof of their common origin lies with the person who takes that view; and each case must be decided on its own evidence, and not on analogy, if our conclusions in this way are to be of real value. Of course we must often jump at conclusions from imperfect evidence. I should like to write an essay on species some day; but before I should have time to do it, in my plodding way, I hope you or Hooker will do it, and much better far. I am most glad to be in conference with Hooker and yourself on these matters, and I think we may, or rather you may, in a few years settle the question as to whether Agassiz's or Hooker's views are correct; they are certainly widely different. Apropos to this, many thanks for the paper containing your experiments on seeds exposed to sea water. Why has nobody thought of trying the experiment before, instead of taking it for granted that salt water kills seeds? I shall have it nearly all reprinted in "Silliman's Journal" as a nut for Agassiz to crack. LETTER 325. TO ASA GRAY. Down, May 2nd [1856?] I have received your very kind note of April 8th. In truth it is preposterous in me to give you hints; but it will give me real pleasure to write to you just as I talk to Hooker, who says my questions are sometimes suggestive owing to my comparing the ranges, etc., in different kingdoms of Nature. I will make no further apologies about my presumption; but will just tell you (though I am certain there will be VERY little new in what I suggest and ask) the points on which I am very anxious to hear about. I forget whether you include Arctic America, but if so, for comparison with other parts of world, I would exclude the Arctic and Alpine-Arctic, as belonging to a quite distinct category. When excluding the naturalised, I think De Candolle must be right in advising the exclusion (giving list) of plants exclusively found in cultivated land, even when it is not known that they have been introduced by man. I would give list of temperate plants (if any) found in Eastern Asia, China, and Japan, and not elsewhere. Nothing would give me a better idea of the flora of United States than the proportion of its genera to all the genera which are confined to America; and the proportion of genera confined to America and Eastern Asia with Japan; the remaining genera would be common to America and Europe and the rest of world; I presume it would be impossible to show any especial affinity in genera, if ever so few, between America and Western Europe. America might be related to Eastern Asia (always excluding Arctic forms) by a genus having the same species confined to these two regions; or it might be related by the genus having different species, the genus itself not being found elsewhere. The relation of the genera (excluding identical species) seems to me a most important element in geographical distribution often ignored, and I presume of more difficult application in plants than in animals, owing to the wider ranges of plants; but I find in New Zealand (from Hooker) that the consideration of genera with representative species tells the story of relationship even plainer than the identity of the species with the different parts of the world. I should like to see the genera of the United States, say 500 (excluding Arctic and Alpine) divided into three classes, with the proportions given thus:-- 100/500 American genera; 200/500 Old World genera, but not having any identical species in common; 200/500 Old World genera, but having some identical species in common; Supposing that these 200 genera included 600 U.S. plants, then the 600 would be the denominator to the fraction of the species common to the Old World. But I am running on at a foolish length. There is an interesting discussion in De Candolle (about pages 503-514) on the relation of the size of families to the average range of the individual species; I cannot but think, from some facts which I collected long before De Candolle appeared, that he is on wrong scent in having taken families (owing to their including too great a diversity in the constitution of the species), but that if he had taken genera, he would have found that the individual species in large genera range over a greater area than do the species in small genera: I think if you have materials that this would be well worth working out, for it is a very singular relation. With respect to naturalised plants: are any social with you, which are not so in their parent country? I am surprised that the importance of this has not more struck De Candolle. Of these naturalised plants are any or many more variable in your opinion than the average of your United States plants? I am aware how very vague this must be; but De Candolle has stated that the naturalised plants do not present varieties; but being very variable and presenting distinct varieties seems to me rather a different case: if you would kindly take the trouble to answer this question I should be very much obliged, whether or no you will enter on such points in your essay. With respect to such plants, which have their southern limits within your area, are the individuals ever or often stunted in their growth or unhealthy? I have in vain endeavoured to find any botanist who has observed this point; but I have seen some remarks by Barton on the trees in United States. Trees seem in this respect to behave rather differently from other plants. It would be a very curious point, but I fear you would think it out of your essay, to compare the list of European plants in Tierra del Fuego (in Hooker) with those in North America; for, without multiple creation, I think we must admit that all now in T. del Fuego must have travelled through North America, and so far they do concern you. The discussion on social plants (vague as the terms and facts are) in De Candolle strikes me as the best which I have ever seen: two points strike me as eminently remarkable in them; that they should ever be social close to their extreme limits; and secondly, that species having an extremely confined range, yet should be social where they do occur: I should be infinitely obliged for any cases either by letter or publicly on these heads, more especially in regard to a species remaining or ceasing to be social on the confines of its range. There is one other point on which I individually should be extremely much obliged, if you could spare the time to think a little bit and inform me: viz., whether there are any cases of the same species being more variable in United States than in other countries in which it is found, or in different parts of the United States? Wahlenberg says generally that the same species in going south become more variable than in extreme north. Even still more am I anxious to know whether any of the genera, which have most of their species horribly variable (as Rubus or Hieracium are) in Europe, or other parts of the world, are less variable in the United States; or, the reverse case, whether you have any odious genera with you which are less odious in other countries? Any information on this head would be a real kindness to me. I suppose your flora is too great; but a simple list in close columns in small type of all the species, genera, and families, each consecutively numbered, has always struck me as most useful; and Hooker regrets that he did not give such list in introduction to New Zealand and other Flora. I am sure I have given you a larger dose of questions than you bargained for, and I have kept my word and treated you just as I do Hooker. Nevertheless, if anything occurs to me during the next two months, I will write freely, believing that you will forgive me and not think me very presumptuous. How well De Candolle shows the necessity of comparing nearly equal areas for proportion of families! I have re-read this letter, and it is really not worth sending, except for my own sake. I see I forgot, in beginning, to state that it appeared to me that the six heads of your Essay included almost every point which could be desired, and therefore that I had little to say. LETTER 326. TO J.D. HOOKER. (326/1. On July 5th, 1856, Darwin wrote to Sir J.D. Hooker:-- "I am going mad and am in despair over your confounded Antarctic island flora. Will you read over the Tristan list, and see if my remarks on it are at all accurate. I cannot make out why you consider the vegetation so Fuegian.") Down, 8th [July, 1856]. I do hope that this note may arrive in time to save you trouble in one respect. I am perfectly ashamed of myself, for I find in introduction to Flora of Fuegia (326/2. "Flora Antarctica," page 216. "Though only 1,000 miles distant from the Cape of Good Hope, and 3,000 from the Strait of Magalhaens, the botany of this island [Tristan d'Acunha] is far more intimately allied to that of Fuegia than Africa." Hooker goes on to say that only Phylica and Pelargonium are Cape forms, while seven species, or one-quarter of the flora, "are either natives of Fuegia or typical of South American botany, and the ferns and Lycopodia exhibit a still stronger affinity.") a short discussion on Tristan plants, which though scored [i.e. marked in pencil] I had quite forgotten at the time, and had thought only of looking into introduction to New Zealand Flora. It was very stupid of me. In my sketch I am forced to pick out the most striking cases of species which favour the multiple creation doctrine, without indeed great continental extensions are admitted. Of the many wonderful cases in your books, the one which strikes me most is that list of species, which you made for me, common to New Zealand and America, and confined to southern hemisphere; and in this list those common to Chile and New Zealand seem to me the most wondrous. I have copied these out and enclosed them. Now I will promise to ask no more questions, if you will tell me a little about these. What I want to know is, whether any or many of them are mountain plants of Chile, so as to bring them in some degree (like the Chonos plants) under the same category with the Fuegian plants? I see that all the genera (Edwardsia even having Sandwich Island and Indian species) are wide-ranging genera, except Myosurus, which seems extra wonderful. Do any of these genera cling to seaside? Are the other species of these genera wide rangers? Do be a good Christian and not hate me. I began last night to re-read your Galapagos paper, and to my taste it is quite admirable: I see in it some of the points which I thought best in A. De Candolle! Such is my memory. Lyell will not express any opinion on continental extensions. (326/3. See Letters 47, 48.) LETTER 327. TO C. LYELL. Down, July 8th [1856]. Very many thanks for your two notes, and especially for Maury's map: also for books which you are going to lend me. I am sorry you cannot give any verdict on continental extensions; and I infer that you think my argument of not much weight against such extensions; I know I wish I could believe. (327/1. This paragraph is published in the "Life and Letters," II., page 78; it refers to a letter (June 25th, 1856, "Life and Letters," II., page 74) giving Darwin's arguments against the doctrine of "Continental Extension." See Letters 47, 48.) I have been having a look at Maury (which I once before looked at), and in respect to Madeira & Co. I must say, that the chart seems to me against land-extension explaining the introduction of organic beings. Madeira, the Canaries and Azores are so tied together, that I should have thought they ought to have been connected by some bank, if changes of level had been connected with their organic relation. The Azores ought, too, to have shown more connection with America. I had sometimes speculated whether icebergs could account for the greater number of European plants and their more northern character on the Azores, compared with Madeira; but it seems dangerous until boulders are found there. (327/2. See "Life and Letters," II., page 112, for a letter (April 26th, 1858) in which Darwin exults over the discovery of boulders on the Azores and the fulfilment of the prophecy, which he was characteristically half inclined to ascribe to Lyell.) One of the more curious points in Maury is, as it strikes me, in the little change which about 9,000 feet of sudden elevation would make in the continent visible, and what a prodigious change 9,000 feet subsidence would make! Is the difference due to denudation during elevation? Certainly 12,000 feet elevation would make a prodigious change. I have just been quoting you in my essay on ice carrying seeds in the southern hemisphere, but this will not do in all the cases. I have had a week of such hard labour in getting up the relations of all the Antarctic flora from Hooker's admirable works. Oddly enough, I have just finished in great detail, giving evidence of coolness in tropical regions during the Glacial epoch, and the consequent migration of organisms through the tropics. There are a good many difficulties, but upon the whole it explains much. This has been a favourite notion with me, almost since I wrote on erratic boulders of the south. It harmonises with the modification of species; and without admitting this awful postulate, the Glacial epoch in the south and tropics does not work in well. About Atlantis, I doubt whether the Canary Islands are as much more related to the continent as they ought to be, if formerly connected by continuous land. Hooker, with whom I have formerly discussed the notion of the world or great belts of it having been cooler, though he at first saw great difficulties (and difficulties there are great enough), I think is much inclined to adopt the idea. With modification of specific forms it explains some wondrous odd facts in distribution. But I shall never stop if I get on this subject, on which I have been at work, sometimes in triumph, sometimes in despair, for the last month. LETTER 328. ASA GRAY TO CHARLES DARWIN. Received August 20th, 1856. I enclose you a proof of the last page, that you may see what our flora amounts to. The genera of the Cryptogams (Ferns down to Hepaticae) are illustrated in fourteen crowded plates. So that the volume has become rather formidable as a class-book, which it is intended for. I have revised the last proofs to-day. The publishers will bring it out some time in August. Meanwhile, I am going to have a little holiday, which I have earned, little as I can spare the time for it. And my wife and I start on Friday to visit my mother and friends in West New York, and on our way back I will look in upon the scientific meeting at Albany on the 20th inst., or later, just to meet some old friends there. Why could not you come over, on the urgent invitation given to European savans--and free passage provided back and forth in the steamers? Yet I believe nobody is coming. Will you not come next year, if a special invitation is sent you on the same terms? Boott lately sent me your photograph, which (though not a very perfect one) I am well pleased to have... But there is another question in your last letter--one about which a person can only give an impression--and my impression is that, speaking of plants of a well-known flora, what we call intermediate varieties are generally less numerous in individuals than the two states which they connect. That this would be the case in a flora where things are put as they naturally should be, I do not much doubt; and the wider are your views about species (say, for instance, with Dr. Hooker's very latitudinarian notions) the more plainly would this appear. But practically two things stand hugely in the way of any application of the fact or principle, if such it be. 1. Our choice of what to take as the typical forms very often is not free. We take, e.g., for one of them the particular form of which Linnaeus, say, happened to have a specimen sent him, and on which [he] established the species; and I know more than one case in which that is a rare form of a common species; the other variety will perhaps be the opposite extreme--whether the most common or not, or will be what L. or [illegible] described as a 2nd species. Here various intermediate forms may be the most abundant. 2. It is just the same thing now, in respect to specimens coming in from our new western country. The form which first comes, and is described and named, determines the specific character, and this long sticks as the type, though in fact it may be far from the most common form. Yet of plants very well known in all their aspects, I can think of several of which we recognise two leading forms, and rarely see anything really intermediate, such as our Mentha borealis, its hairy and its smooth varieties. Your former query about the variability of naturalised plants as compared with others of same genera, I had not forgotten, but have taken no steps to answer. I was going hereafter to take up our list of naturalised plants and consider them--it did not fall into my plan to do it yet. Off-hand I can only say that it does not strike me that our introduced plants generally are more variable, nor as variable, perhaps, as the indigenous. But this is a mere guess. When you get my sheets of first part of article in "Silliman's Journal," remember that I shall be most glad of free critical comments; and the earlier I get them the greater use they will be to me... One more favour. Do not, I pray you, speak of your letters troubling me. I should be sorry indeed to have you stop, or write more rarely, even though mortified to find that I can so seldom give you the information you might reasonably expect. LETTER 329. TO ASA GRAY. Down, August 24th [1856]. I am much obliged for your letter, which has been very interesting to me. Your "indefinite" answers are perhaps not the least valuable part; for Botany has been followed in so much more a philosophical spirit than Zoology, that I scarcely ever like to trust any general remark in Zoology without I find that botanists concur. Thus, with respect to intermediate varieties being rare, I found it put, as I suspected, much too strongly (without the limitations and doubts which you point out) by a very good naturalist, Mr. Wollaston, in regard to insects; and if it could be established as true it would, I think, be a curious point. Your answer in regard to the introduced plants not being particularly variable, agrees with an answer which Mr. H.C. Watson has sent me in regard to British agrarian plants, or such (whether or no naturalised) [as] are now found only in cultivated land. It seems to me very odd, without any theoretical notions of any kind, that such plants should not be variable; but the evidence seems against it. Very sincere thanks for your kind invitation to the United States: in truth there is nothing which I should enjoy more; but my health is not, and will, I suppose, never be strong enough, except for the quietest routine life in the country. I shall be particularly glad of the sheets of your paper on geographical distribution; but it really is unlikely in the highest degree that I could make any suggestions. With respect to my remark that I supposed that there were but few plants common to Europe and the United States, not ranging to the Arctic regions; it was founded on vague grounds, and partly on range of animals. But I took H.C. Watson's remarks (1835) and in the table at the end I found that out of 499 plants believed to be common to the Old and New World, only 110 did not range on either side of the Atlantic up to the Arctic region. And on writing to Mr. Watson to ask whether he knew of any plants not ranging northward of Britain (say 55 deg) which were in common, he writes to me that he imagines there are very few; with Mr. Syme's assistance he found some 20 to 25 species thus circumstanced, but many of them, from one cause or other, he considered doubtful. As examples, he specifies to me, with doubt, Chrysosplenium oppositifolium; Isnardia palustris; Astragalus hypoglottis; Thlaspi alpestre; Arenaria verna; Lythrum hyssopifolium. I hope that you will be inclined to work out for your next paper, what number, of your 321 in common, do not range to Arctic regions. Such plants seem exposed to such much greater difficulties in diffusion. Very many thanks for all your kindness and answers to my questions. P.S.--If anything should occur to you on variability of naturalised or agrarian plants, I hope that you will be so kind as to let me hear, as it is a point which interests me greatly. LETTER 330. ASA GRAY TO CHARLES DARWIN. Cambridge, Mass., September 23rd, 1856. Dr. Engelmann, of St. Louis, Missouri, who knew European botany well before he came here, and has been an acute observer generally for twenty years or more in this country, in reply to your question I put to him, promptly said introduced plants are not particularly variable--are not so variable as the indigenous plants generally, perhaps. The difficulty of answering your questions, as to whether there are any plants social here which are not so in the Old World, is that I know so little about European plants in nature. The following is all I have to contribute. Lately, I took Engelmann and Agassiz on a botanical excursion over half a dozen miles of one of our seaboard counties; when they both remarked that they never saw in Europe altogether half so much barberry as in that trip. Through all this district B. vulgaris may be said to have become a truly social plant in neglected fields and copses, and even penetrating into rather close old woods. I always supposed that birds diffused the seeds. But I am not clear that many of them touch the berries. At least, these hang on the bushes over winter in the greatest abundance. Perhaps the barberry belongs to a warmer country than north of Europe, and finds itself more at home in our sunny summers. Yet out of New England it seems not to spread at all. Maruta Cotula, fide Engelmann, is a scattered and rather scarce plant in Germany. Here, from Boston to St. Louis, it covers the roadsides, and is one of our most social plants. But this plant is doubtless a native of a hotter country than North Germany. St. John's-wort (Hypericum perforatum) is an intrusive weed in all hilly pastures, etc., and may fairly be called a social plant. In Germany it is not so found, fide Engelmann. Verbascum Thapsus is diffused over all the country, is vastly more common here than in Germany, fide Engelmann. I suppose Erodium cicutarium was brought to America with cattle from Spain: it seems to be widely spread over South America out of the Tropics. In Atlantic U.S. it is very scarce and local. But it fills California and the interior of Oregon quite back to the west slope of the Rocky Mountains. Fremont mentions it as the first spring food for his cattle when he reached the western side of the Rocky Mountains. And hardly anybody will believe me when I declare it an introduced plant. I daresay it is equally abundant in Spain. I doubt if it is more so. Engelmann and I have been noting the species truly indigenous here which, becoming ruderal or campestral, are increasing in the number of individuals instead of diminishing as the country becomes more settled and forests removed. The list of our wild plants which have become true weeds is larger than I had supposed, and these have probably all of them increased their geographical range--at least, have multiplied in numbers in the Northern States since settlements. Some time ago I sent a copy of the first part of my little essay on the statistics (330/1. "Statistics of the Flora of the Northern U.S." ("Silliman's Journal," XXII. and XXIII.)) of our Northern States plants to Trubner & Co., 12, Paternoster Row, to be thence posted to you. It may have been delayed or failed, so I post another from here. This is only a beginning. Range of species in latitude must next be tabulated--disjoined species catalogued (i.e. those occurring in remote and entirely separated areas--e.g. Phryma, Monotropa uniflora, etc.)--then some of the curious questions you have suggested--the degree of consanguinity between the related species of our country and other countries, and the comparative range of species in large and small genera, etc., etc. Now, is it worth while to go on at this length of detail? There is no knowing how much space it may cover. Yet, after all, facts in all their fullness is what is wanted, and those not gathered to support (or even to test) any foregone conclusions. It will be prosy, but it may be useful. Then I have no time properly to revise MSS. and correct oversights. To my vexation, in my short list of our alpine species I have left out, in some unaccountable manner, two of the most characteristic--viz., Cassiope hypnoides and Loiseleuria procumbens. Please add them on page 28. There is much to be said about our introduced plants. But now, and for some time to come, I must be thinking of quite different matters. I mean to continue this essay in the January number--for which my MSS. must be ready about the 1st of November. I have not yet attempted to count them up; but of course I am prepared to believe that fully three-fourths of our species common to Europe will [be] found to range northward to the Arctic regions. I merely meant that I had in mind a number that do not; I think the number will not be very small; and I thought you were under the impression that very few absolutely did not so extend northwards. The most striking case I know is that of Convallaria majalis, in the mountains [of] Virginia and North Carolina, and not northward. I believe I mentioned this to you before. LETTER 331. TO ASA GRAY. Down, October 12th [1856]. I received yesterday your most kind letter of the 23rd and your "Statistics," and two days previously another copy. I thank you cordially for them. Botanists write, of course, for botanists; but, as far as the opinion of an "outsider" goes, I think your paper admirable. I have read carefully a good many papers and works on geographical distribution, and I know of only one essay (viz. Hooker's "New Zealand") that makes any approach to the clearness with which your paper makes a non-botanist appreciate the character of the flora of a country. It is wonderfully condensed (what labour it must have required!). You ask whether such details are worth giving: in my opinion, there is literally not one word too much. I thank you sincerely for the information about "social" and "varying plants," and likewise for giving me some idea about the proportion (i.e. 1/4th) of European plants which you think do not range to the extreme North. This proportion is very much greater than I had anticipated, from what I picked up in conversation, etc. To return to your "Statistics." I daresay you will give how many genera (and orders) your 260 introduced plants belong to. I see they include 113 genera non-indigenous. As you have probably a list of the introduced plants, would it be asking too great a favour to send me, per Hooker or otherwise, just the total number of genera and orders to which the introduced plants belong. I am much interested in this, and have found De Candolle's remarks on this subject very instructive. Nothing has surprised me more than the greater generic and specific affinity with East Asia than with West America. Can you tell me (and I will promise to inflict no other question) whether climate explains this greater affinity? or is it one of the many utterly inexplicable problems in botanical geography? Is East Asia nearly as well known as West America? so that does the state of knowledge allow a pretty fair comparison? I presume it would be impossible, but I think it would make in one point your tables of generic ranges more clear (admirably clear as they seem to me) if you could show, even roughly, what proportion of the genera in common to Europe (i.e. nearly half) are very general or mundane rangers. As your results now stand, at the first glance the affinity seems so very strong to Europe, owing, as I presume, to nearly half of the genera including very many genera common to the world or large portions of it. Europe is thus unfairly exalted. Is this not so? If we had the number of genera strictly, or nearly strictly European, one could compare better with Asia and Southern America, etc. But I dare say this is a Utopian wish, owing to difficulty of saying what genera to call mundane; nor have I my ideas at all clear on the subject, and I have expressed them even less clearly than I have them. I am so very glad that you intend to work out the north range of the 321 European species; for it seems to me the by far most important element in their distribution. And I am equally glad that you intend to work out range of species in regard to size of genera--i.e. number of species in genus. I have been attempting to do this in a very few cases, but it is folly for any one but a botanist to attempt it. I must think that De Candolle has fallen into error in attempting to do this for orders instead of for genera--for reasons with which I will not trouble you. LETTER 332. TO J.D. HOOKER. (332/1. The "verdict" referred to in the following letter was Sir J.D. Hooker's opinion on Darwin's MS. on geographical distribution. The first paragraph has been already published in "Life and Letters," II., page 86.) Down, November 4th [1856]. I thank you more cordially than you will think probable for your note. Your verdict has been a great relief. On my honour I had no idea whether or not you would say it was (and I knew you would say it very kindly) so bad, that you would have begged me to have burnt the whole. To my own mind my MS. relieved me of some few difficulties, and the difficulties seemed to me pretty fairly stated; but I had become so bewildered with conflicting facts--evidence, reasoning and opinions--that I felt to myself that I had lost all judgment. Your general verdict is incomparably more favourable than I had anticipated. Very many thanks for your invitation. I had made up my mind, on my poor wife's account, not to come up to next Phil. Club; but I am so much tempted by your invitation, and my poor dear wife is so good-natured about it, that I think I shall not resist--i.e., if she does not get worse. I would come to dinner at about same time as before, if that would suit you, and I do not hear to the contrary; and would go away by the early train--i.e., about 9 o'clock. I find my present work tries me a good deal, and sets my heart palpitating, so I must be careful. But I should so much like to see Henslow, and likewise meet Lindley if the fates will permit. You will see whether there will be time for any criticism in detail on my MS. before dinner: not that I am in the least hurry, for it will be months before I come again to Geographical Distribution; only I am afraid of your forgetting any remarks. I do not know whether my very trifling observations on means of distribution are worth your reading, but it amuses me to tell them. The seeds which the eagle had in [its] stomach for eighteen hours looked so fresh that I would have bet five to one that they would all have grown; but some kinds were ALL killed, and two oats, one canary-seed, one clover, and one beet alone came up! Now I should have not cared swearing that the beet would not have been killed, and I should have fully expected that the clover would have been. These seeds, however, were kept for three days in moist pellets, damp with gastric juice, after being ejected, which would have helped to have injured them. Lately I have been looking, during a few walks, at excrement of small birds. I have found six kinds of seeds, which is more than I expected. Lastly, I have had a partridge with twenty-two grains of dry earth on one foot, and to my surprise a pebble as big as a tare seed; and I now understand how this is possible, for the bird scratches itself, [and the] little plumous feathers make a sort of very tenacious plaister. Think of the millions of migratory quails (332/2. See "Origin," Edition I., page 363, where the millions of migrating quails occur again.), and it would be strange if some plants have not been transported across good arms of the sea. Talking of this, I have just read your curious Raoul Island paper. (332/3. "Linn. Soc. Journal." I., 1857.) This looks more like a case of continuous land, or perhaps of several intervening, now lost, islands than any (according to my heterodox notions) I have yet seen. The concordance of the vegetation seems so complete with New Zealand, and with that land alone. I have read Salter's paper and can hardly stomach it. I wonder whether the lighters were ever used to carry grain and hay to ships. (332/4. Salter, "Linn. Soc. Journal," I., 1857, page 140, "On the Vitality of Seeds after prolonged Immersion in the Sea." It appears that in 1843 the mud was scraped from the bottom of the channels in Poole Harbour, and carried to shore in barges. On this mud a vegetation differing from that of the surrounding shore sprang up.) Adios, my dear Hooker. I thank you most honestly for your assistance--assistance, by the way, now spread over some dozen years. P.S.--Wednesday. I see from my wife's expression that she does not really much like my going, and therefore I must give up, of course, this pleasure. If you should have anything to discuss about my MS., I see that I could get to you by about 12, and then could return by the 2.19 o'clock train, and be home by 5.30 o'clock, and thus I should get two hours' talk. But it would be a considerable exertion for me, and I would not undertake it for mere pleasure's sake, but would very gladly for my book's sake. LETTER 333. J.D. HOOKER TO CHARLES DARWIN. November 9th, 1856. I have finished the reading of your MS., and have been very much delighted and instructed. Your case is a most strong one, and gives me a much higher idea of change than I had previously entertained; and though, as you know, never very stubborn about unalterability of specific type, I never felt so shaky about species before. The first half you will be able to put more clearly when you polish up. I have in several cases made pencil alterations in details as to words, etc., to enable myself to follow better,--some of it is rather stiff reading. I have a page or two of notes for discussion, many of which were answered, as I got further on with the MS., more or less fully. Your doctrine of the cooling of the Tropics is a startling one, when carried to the length of supporting plants of cold temperate regions; and I must confess that, much as I should like it, I can hardly stomach keeping the tropical genera alive in so very cool a greenhouse [pencil note by C.D., "Not so very cool, but northern ones could range further south if not opposed"]. Still I must confess that all your arguments pro may be much stronger put than you have. I am more reconciled to iceberg transport than I was, the more especially as I will give you any length of time to keep vitality in ice, and more than that, will let you transport roots that way also. (333/1. The above letter was pinned to the following note by Mr. Darwin.) In answer to this show from similarity of American, and European and Alpine-Arctic plants, that they have travelled enormously without any change. As sub-arctic, temperate and tropical are all slowly marching toward the equator, the tropical will be first checked and distressed, similarly (333/2. Almost illegible.) the temperate will invade...; after the temperate can [not] advance or do not wish to advance further the arctics will be checked and will invade. The temperates will have been far longer in Tropics than sub-arctics. The sub-arctics will first have to cross temperate [zone] and then Tropics. They would penetrate among strangers, just like the many naturalised plants brought by man, from some unknown advantage. But more, for nearly all have chance of doing so. (333/3. The point of view is more clearly given in the following letters.) LETTER 334. TO J.D. HOOKER. Down, November 15th [1856]. I shall not consider all your notes on my MS. for some weeks, till I have done with crossing; but I have not been able to stop myself meditating on your powerful objection to the mundane cold period (334/1. See Letter 49.), viz. that MANY-fold more of the warm-temperate species ought to have crossed the Tropics than of the sub-arctic forms. I really think that to those who deny the modification of species this would absolutely disprove my theory. But according to the notions which I am testing--viz. that species do become changed, and that time is a most important element (which I think I shall be able to show very clearly in this case)--in such change, I think, the result would be as follows. Some of the warm-temperate forms would penetrate the Tropics long before the sub-arctic, and some might get across the equator long before the sub-arctic forms could do so (i.e. always supposing that the cold came on slowly), and therefore these must have been exposed to new associates and new conditions much longer than the sub-arctic. Hence I should infer that we ought to have in the warm-temperate S. hemisphere more representative or modified forms, and fewer identical species than in comparing the colder regions of the N. and S. I have expressed this very obscurely, but you will understand, I think, what I mean. It is a parallel case (but with a greater difference) to the species of the mountains of S. Europe compared with the arctic plants, the S. European alpine species having been isolated for a longer period than on the arctic islands. Whether there are many tolerably close species in the warm-temperate lands of the S. and N. I know not; as in La Plata, Cape of Good Hope, and S. Australia compared to the North, I know not. I presume it would be very difficult to test this, but perhaps you will keep it a little before your mind, for your argument strikes me as by far the most serious difficulty which has occurred to me. All your criticisms and approvals are in simple truth invaluable to me. I fancy I am right in speaking in this note of the species in common to N. and S. as being rather sub-arctic than arctic. This letter does not require any answer. I have written it to ease myself, and to get you just to bear your argument, under the modification point of view, in mind. I have had this morning a most cruel stab in the side on my notion of the distribution of mammals in relation to soundings. LETTER 335. J.D. HOOKER TO CHARLES DARWIN. Kew, Sunday [November 1856]. I write only to say that I entirely appreciate your answer to my objection on the score of the comparative rareness of Northern warm-temperate forms in the Southern hemisphere. You certainly have wriggled out of it by getting them more time to change, but as you must admit that the distance traversed is not so great as the arctics have to travel, and the extremes of modifying cause not so great as the arctics undergo, the result should be considerably modified thereby. Thus: the sub-arctics have (1) to travel twice as far, (2) taking twice the time, (3) undergoing many more disturbing influences. All this you have to meet by giving the North temperate forms simply more time. I think this will hardly hold water. LETTER 336. TO J.D. HOOKER. Down, November 18th [1856]. Many thanks for your note received this morning; and now for another "wriggle." According to my notions, the sub-arctic species would advance in a body, advancing so as to keep climate nearly the same; and as long as they did this I do not believe there would be any tendency to change, but only when the few got amongst foreign associates. When the tropical species retreated as far as they could to the equator they would halt, and then the confusion would spread back in the line of march from the far north, and the strongest would struggle forward, etc., etc. (But I am getting quite poetical in my wriggles). In short, I THINK the warm-temperates would be exposed very much longer to those causes which I believe are alone efficient in producing change than the sub-arctic; but I must think more over this, and have a good wriggle. I cannot quite agree with your proposition that because the sub-arctic have to travel twice as far they would be more liable to change. Look at the two journeys which the arctics have had from N. to S. and S. to N., with no change, as may be inferred, if my doctrine is correct, from similarity of arctic species in America and Europe and in the Alps. But I will not weary you; but I really and truly think your last objection is not so strong as it looks at first. You never make an objection without doing me much good. Hurrah! a seed has just germinated after 21 1/2 hours in owl's stomach. This, according to ornithologists' calculation, would carry it God knows how many miles; but I think an owl really might go in storm in this time 400 or 500 miles. Adios. Owls and hawks have often been seen in mid-Atlantic. (336/1. An interesting letter, dated November 23rd, 1856, occurs in the "Life and Letters," II., page 86, which forms part of this discussion. On page 87 the following passage occurs: "I shall have to discuss and think more about your difficulty of the temperate and sub-arctic forms in the S. hemisphere than I have yet done. But I am inclined to think that I am right (if my general principles are right), that there would be little tendency to the formation of a new species during the period of migration, whether shorter or longer, though considerable variability may have supervened.) LETTER 337. TO J.D. HOOKER. Down, December 10th [1856]. It is a most tiresome drawback to my satisfaction in writing that, though I leave out a good deal and try to condense, every chapter runs to such an inordinate length. My present chapter on the causes of fertility and sterility and on natural crossing has actually run out to 100 pages MS., and yet I do not think I have put in anything superfluous... I have for the last fifteen months been tormented and haunted by land-mollusca, which occur on every oceanic island; and I thought that the double creationists or continental extensionists had here a complete victory. The few eggs which I have tried both sink and are killed. No one doubts that salt water would be eminently destructive to them; and I was really in despair, when I thought I would try them when torpid; and this day I have taken a lot out of the sea-water, after exactly seven days' immersion. (337/1. This method of dispersal is not given in the "Origin"; it seems, therefore, probable that further experiments upset the conclusion drawn in 1856. This would account for the satisfaction expressed in the following year at the discovery of another method, on which Darwin wrote to Sir J.D. Hooker: "The distribution of fresh-water molluscs has been a horrid incubus to me, but I think I know my way now. When first hatched they are very active, and I have had thirty or forty crawl on a dead duck's foot; and they cannot be jerked off, and will live fifteen or even twenty-four hours out of water" ("Life and Letters," II., page 93). The published account of these experiments is in the "Origin," Edition I., page 385.) Some sink and some swim; and in both cases I have had (as yet) one come to life again, which has quite astonished and delighted me. I feel as if a thousand-pound weight was taken off my back. Adios, my dear, kind friend. I must tell you another of my profound experiments! [Frank] said to me: "Why should not a bird be killed (by hawk, lightning, apoplexy, hail, etc.) with seed in its crop, and it would swim?" No sooner said than done: a pigeon has floated for thirty days in salt water with seeds in its crop, and they have grown splendidly; and to my great surprise even tares (Leguminosae, so generally killed by sea-water), which the bird had naturally eaten, have grown well. You will say gulls and dog-fish, etc., would eat up the carcase, and so they would 999 times out of a thousand, but one might escape: I have seen dead land-birds in sea-drift. LETTER 338. ASA GRAY TO CHARLES DARWIN. (338/1. In reply to Darwin's letter given in "Life and Letters," II., page 88.) Cambridge, Mass., February 16th, 1857. I meant to have replied to your interesting letter of January 1st long before this time, and also that of November 24th, which I doubt if I have ever acknowledged. But after getting my school-book, Lessons in Botany, off my hands--it taking up time far beyond what its size would seem to warrant--I had to fall hard at work upon a collection of small size from Japan--mostly N. Japan, which I am only just done with. As I expected, the number of species common to N. America is considerably increased in this collection, as also the number of closely representative species in the two, and a pretty considerable number of European species too. I have packed off my MSS. (though I hardly know what will become of it), or I would refer you to some illustrations. The greater part of the identical species (of Japan and N. America) are of those extending to or belonging to N.W. coast of America, but there are several peculiar to Japan and E. U. States: e.g. our Viburnum lantanoides is one of Thunberg's species. De Candolle's remarkable case of Phryma, which he so dwells upon, turns out, as Dr. Hooker said it would, to be only one out of a great many cases of the same sort. (Hooker brought Monotropa uniflora, you know, from the Himalayas; and now, by the way, I have it from almost as far south, i.e., from St. Fee, New Granada)... Well, I never meant to draw any conclusions at all, and am very sorry that the only one I was beguiled into should "rile" (338/2. "One of your conclusions makes me groan, viz., that the line of connection of the strictly alpine plants is through Greenland. I should extremely like to see your reasons published in detail, for it 'riles' me (this is a proper expression, is it not?) dreadfully" (Darwin to Gray, January 1st, 1857, "Life and Letters," II., page 89).) you, as you say it does,--that on page 73 of my second article: for if it troubles you it is not likely to be sound. Of course I had no idea of laying any great stress upon the fact (at first view so unexpected to me) that one-third of our alpine species common to Europe do not reach the Arctic circle; but the remark which I put down was an off-hand inference from what you geologists seem to have settled--viz., that the northern regions must have been a deal cooler than they are now--the northern limit of vegetation therefore much lower than now--about the epoch when it would seem probable that the existing species of our plants were created. At any rate, during the Glacial period there could have been no phaenogamous plants on our continent anywhere near the polar regions; and it seems a good rule to look in the first place for the cause or reason of what now is, in that which immediately preceded. I don't see that Greenland could help us much, but if there was any interchange of species between N. America and N. Europe in those times, was not the communication more likely to be in lower latitudes than over the pole? If, however, you say--as you may have very good reasons for saying--that the existing species got their present diffusion before the Glacial epoch, I should have no answer. I suppose you must needs assume very great antiquity for species of plants in order to account for their present dispersion, so long as we cling--as one cannot but do--to the idea of the single birthplace of species. I am curious to see whether, as you suggest, there would be found a harmony or close similarity between the geographical range in this country of the species common to Europe and those strictly representative or strictly congeneric with European species. If I get a little time I will look up the facts: though, as Dr. Hooker rightly tells me, I have no business to be running after side game of any sort, while there is so much I have to do--much more than I shall ever do probably--to finish undertakings I have long ago begun. ...As to your P.S. If you have time to send me a longer list of your protean genera, I will say if they seem to be protean here. Of those you mention:-- Salix, I really know nothing about. Rubus, the N. American species, with one exception, are very clearly marked indeed. Mentha, we have only one wild species; that has two pretty well-marked forms, which have been taken for species; one smooth, the other hairy. Saxifraga, gives no trouble here. Myosotis, only one or two species here, and those very well marked. Hieracium, few species, but pretty well marked. Rosa, putting down a set of nominal species, leaves us four; two of them polymorphous, but easy to distinguish... LETTER 339. TO J.D. HOOKER. Down, [1857?] One must judge by one's own light, however imperfect, and as I have found no other book (339/1. A. De Candolle's "Geographie Botanique," 1855.) so useful to me, I am bound to feel grateful: no doubt it is in main part owing to the concentrated light of the noble art of compilation. (339/2. See Letter 49.) I was aware that he was not the first who had insisted on range of Monocots. (Was not R. Brown [with] Flinders?) (339/3. M. Flinders' "Voyage to Terra Australis in 1801-3, in H.M.S. 'Investigator'"; with "Botanical Appendix," by Robert Brown, London, 1814.), and I fancy I only used expression "strongly insisted on,"--but it is quite unimportant. If you and I had time to waste, I should like to go over his [De Candolle's] book and point out the several subjects in which I fancy he is original. His remarks on the relations of naturalised plants will be very useful to me; on the ranges of large families seemed to me good, though I believe he has made a great blunder in taking families instead of smaller groups, as I have been delighted to find in A. Gray's last paper. But it is no use going on. I do so wish I could understand clearly why you do not at all believe in accidental means of dispersion of plants. The strongest argument which I can remember at this instant is A. de C., that very widely ranging plants are found as commonly on islands as over continents. It is really provoking to me that the immense contrast in proportion of plants in New Zealand and Australia seems to me a strong argument for non-continuous land; and this does not seem to weigh in the least with you. I wish I could put myself in your frame of mind. In Madeira I find in Wollaston's books a parallel case with your New Zealand case--viz., the striking absence of whole genera and orders now common in Europe, and (as I have just been hunting out) common in Europe in Miocene periods. Of course I can offer no explanation why this or that group is absent; but if the means of introduction have been accidental, then one might expect odd proportions and absences. When we meet, do try and make me see more clearly than I do, your reasons. LETTER 340. TO J.D. HOOKER. Down, November 14th [1858]. I am heartily glad to hear that my Lyellian notes have been of the slightest use to you. (340/1. The Copley Medal was given to Sir Charles Lyell in 1858. Mr. Darwin supplied Sir J.D. Hooker, who was on the Council of the Royal Society, with notes for the reasons for the award. See Letter 69.) I do not think the view is exaggerated... Your letter and lists have MOST DEEPLY interested me. First for less important point, about hermaphrodite trees. (340/2. See "Life and Letters," II., page 89. In the "Origin," Edition I., page 100, the author quotes Dr. Hooker to the effect that "the rule does not hold in Australia," i.e., that trees are not more generally unisexual than other plants. In the 6th edition, page 79, Darwin adds, "but if most of the Australian trees are dichogamous, the same result would follow as if they bore flowers with separated sexes.") It is enough to knock me down, yet I can hardly think that British N. America and New Zealand should all have been theoretically right by chance. Have you at Kew any Eucalyptus or Australian Mimosa which sets its seeds? if so, would it be very troublesome to observe when pollen is mature, and whether pollen-tubes enter stigma readily immediately that pollen is mature or some little time afterwards? though if pollen is not mature for some little time after flower opens, the stigma might be ready first, though according to C.C. Sprengel this is a rarer case. I wrote to Muller for chance of his being able and willing to observe this. Your fact of greater number of European plants (N.B.--But do you mean greater percentage?) in Australia than in S. America is astounding and very unpleasant to me; for from N.W. America (where nearly the same flora exists as in Canada?) to T. del Fuego, there is far more continuous high land than from Europe to Tasmania. There must have, I should think, existed some curious barrier on American High-Road: dryness of Peru, excessive damp of Panama, or some other confounded cause, which either prevented immigration or has since destroyed them. You say I may ask questions, and so I have on enclosed paper; but it will of course be a very different thing whether you will think them worth labour of answering. May I keep the lists now returned? otherwise I will have them copied. You said that you would give me a few cases of Australian forms and identical species going north by Malay Archipelago mountains to Philippines and Japan; but if these are given in your "Introduction" this will suffice for me. (340/3. See Hooker's "Introductory Essay," page l.) Your lists seem to me wonderfully interesting. According to my theoretical notions, I am not satisfied with what you say about local plants in S.W. corner of Australia (340/4. Sir Joseph replied in an undated letter: "Thanks for your hint. I shall be very cautious how I mention any connection between the varied flora and poor soil of S.W. Australia...It is not by the way only that the species are so numerous, but that these and the genera are so confoundedly well marked. You have, in short, an incredible number of VERY LOCAL, WELL MARKED genera and species crowded into that corner of Australia." See "Introductory Essay to the Flora of Tasmania," 1859, page li.), and the seeds not readily germinating: do be cautious on this; consider lapse of time. It does not suit my stomach at all. It is like Wollaston's confined land-snails in Porto Santo, and confined to same spots since a Tertiary period, being due to their slow crawling powers; and yet we know that other shell-snails have stocked a whole country within a very few years with the same breeding powers, and same crawling powers, when the conditions have been favourable to the life of the introduced species. Hypothetically I should rather look at the case as owing to--but as my notions are not very simple or clear, and only hypothetical, they are not worth inflicting on you. I had vowed not to mention my everlasting Abstract (340/5. The "Origin of Species" was abbreviated from the MS. of an unpublished book.) to you again, for I am sure I have bothered you far more than enough about it; but as you allude to its previous publication I may say that I have chapters on Instinct and Hybridism to abstract, which may take a fortnight each; and my materials for Palaeontology, Geographical Distribution and Affinities being less worked up, I daresay each of these will take me three weeks, so that I shall not have done at soonest till April, and then my Abstract will in bulk make a small volume. I never give more than one or two instances, and I pass over briefly all difficulties, and yet I cannot make my Abstract shorter, to be satisfactory, than I am now doing, and yet it will expand to small volume. LETTER 341. TO J.D. HOOKER. Down [November?] 27th [1858]. What you say about the Cape flora's direct relation to Australia is a great trouble to me. Does not Abyssinia highland, (341/1. In a letter to Darwin, December 21st (?), 1858, Sir J.D. Hooker wrote: "Highlands of Abyssinia will not help you to connect the Cape and Australian temperate floras: they want all the types common to both, and, worse than that, India notably wants them. Proteaceae, Thymeleae, Haemodoraceae, Acacia, Rutaceae, of closely allied genera (and in some cases species), are jammed up in S.W. Australia, and C.B.S. [Cape of Good Hope]: add to this the Epacrideae (which are mere (paragraph symbol) of Ericaceae) and the absence or rarity of Rasaceae, etc., etc., and you have an amount [of] similarity in the floras and dissimilarity to that of Abyssinia and India in the same features that does demand an explanation in any theoretical history of Southern vegetation."), and the mountains on W. coast in some degree connect the extra-tropical floras of Cape and Australia? To my mind the enormous importance of the Glacial period rises daily stronger and stronger. I am very glad to hear about S.E. and S.W. Australia: I suspected after my letter was gone that the case must be as it is. You know of course that nearly the same rule holds with birds and mammals. Several years ago I reviewed in the "Annals of Natural History," (341/2. "Annals and Mag. of Nat. Hist." Volume XIX., 1847, pages 53-56, an unsigned review of "A Natural History of the Mammalia," by G.R. Waterhouse, Volume I. The passage referred to is at page 55: "The fact of South Australia possessing only few peculiar species, it having been apparently colonised from the eastern and western coasts, is very interesting; for we believe that Mr. Robert Brown has shown that nearly the same remark is applicable to the plants; and Mr. Gould finds that most of the birds from these opposite shores, though closely allied, are distinct. Considering these facts, together with the presence in South Australia of upraised modern Tertiary deposits and of extinct volcanoes, it seems probable that the eastern and western shores once formed two islands, separated from each other by a shallow sea, with their inhabitants generically, though not specifically, related, exactly as are those of New Guinea and Northern Australia, and that within a geologically recent period a series of upheavals converted the intermediate sea into those desert plains which are now known to stretch from the southern coast far northward, and which then became colonised from the regions to the east and west." On this point see Hooker's "Introductory Essay to the Flora of Tasmania," page ci, where Jukes' views are discussed. For an interesting account of the bearings of the submergence of parts of Australia, see Thiselton-Dyer, "R. Geogr. Soc. Jour." XXII., No. 6.) Waterhouse's "Mammalia," and speculated that these two corners, now separated by gulf and low land, must have existed as two large islands; but it is odd that productions have not become more mingled; but it accords with, I think, a very general rule in the spreading of organic beings. I agree with what you say about Lyell; he learns more by word of mouth than by reading. Henslow has just gone, and has left me in a fit of enthusiastic admiration of his character. He is a really noble and good man. LETTER 342. TO G. BENTHAM. Down, December 1st [1858?]. I thank you for so kindly taking the trouble of writing to me, on naturalised plants. I did not know of, or had forgotten, the clover case. How I wish I knew what plants the clover took the place of; but that would require more accurate knowledge of any one piece of ground than I suppose any one has. In the case of trees being so long-lived, I should think it would be extremely difficult to distinguish between true and new spreading of a species, and a rotation of crop. With respect to your idea of plants travelling west, I was much struck by a remark of yours in the penultimate "Linnean Journal" on the spreading of plants from America near Behring Straits. Do you not consider so many more seeds and plants being taken from Europe to America, than in a reverse direction, would go some way to account for comparative fewness of naturalised American plants here? Though I think one might wildly speculate on European weeds having become well fitted for cultivated land, during thousands of years of culture, whereas cultivated land would be a new home for native American weeds, and they would not consequently be able to beat their European rivals when put in contest with them on cultivated land. Here is a bit of wild theory! (342/1. See Asa Gray, "Scientific Papers," 1889, Volume II., page 235, on "The Pertinacity and Predominance of Weeds," where the view here given is adopted. In a letter to Asa Gray (November 6th, 1862), published in the "Life and Letters," II., page 390, Darwin wrote: "Does it not hurt your Yankee pride that we thrash you so confoundedly? I am sure Mrs. Gray will stick up for your own weeds. Ask her whether they are not more honest downright good sort of weeds.") But I did not sit down intending to scribble thus; but to beg a favour of you. I gave Hooker a list of species of Silene, on which Gartner has experimentised in crossing: now I want EXTREMELY to be permitted to say that such and such are believed by Mr. Bentham to be true species, and such and such to be only varieties. Unfortunately and stupidly, Gartner does not append author's name to the species. Thank you heartily for what you say about my book; but you will be greatly disappointed; it will be grievously too hypothetical. It will very likely be of no other service than collocating some facts; though I myself think I see my way approximately on the origin of species. But, alas, how frequent, how almost universal it is in an author to persuade himself of the truth of his own dogmas. My only hope is that I certainly see very many difficulties of gigantic stature. If you can remember any cases of one introduced species beating out or prevailing over another, I should be most thankful to hear it. I believe the common corn-poppy has been seen indigenous in Sicily. I should like to know whether you suppose that seedlings of this wild plant would stand a contest with our own poppy; I should almost expect that our poppies were in some degree acclimatised and accustomed to our cornfields. If this could be shown to be so in this and other cases, I think we could understand why many not-trained American plants would not succeed in our agrarian habitats. LETTER 343. TO J.D. HOOKER. (343/1. Mr. Darwin used the knowledge of the spread of introduced plants in North America and Australia to throw light on the cosmic migration of plants. Sir J.D. Hooker apparently objected that it was not fair to argue from agrarian to other plants; he also took a view differing slightly from that of Darwin as to climatal and other natural conditions favouring introduced plants in Australia.) Down, January 28th, 1859. Thanks about glaciers. It is a pleasure and profit to me to write to you, and as in your last you have touched on naturalised plants of Australia, I suppose you would not dislike to hear what I can say in answer. At least I know you would not wish me to defer to your authority, as long as not convinced. I quite agree to what you say about our agrarian plants being accustomed to cultivated land, and so no fair test. Buckman has, I think, published this notion with respect to North America. With respect to roadside plants, I cannot feel so sure that these ought to be excluded, as animals make roads in many wild countries. (343/2. In the account of naturalised plants in Australia in Sir J.D. Hooker's "Introductory Essay to the Flora of Tasmania," 1859, page cvi, many of the plants are marked "Britain--waste places," "Europe--cornfields," etc. In the same list the species which have also invaded North America--a large number--are given. On the margin of Darwin's copy is scribbled in pencil: "Very good, showing how many of the same species are naturalised in Australia and United States, with very different climates; opposed to your conclusion." Sir Joseph supposed that one chief cause of the intrusion of English plants in Australia, and not vice versa, was the great importation of European seed to Australia and the scanty return of Australian seed.) I have now looked and found passage in F. Muller's (343/3. Ferdinand Muller.) letter to me, in which he says: "In the WILDERNESSES of Australia some European perennials are "advancing in sure progress," "not to be arrested," etc. He gives as instances (so I suppose there are other cases) eleven species, viz., 3. Rumex, Poterium sanguisorba, Potentilla anserina, Medicago sativa, Taraxacum officinale, Marrubium vulgare, Plantago lanceolata, P. major, Lolium perenne. All these are seeding freely. Now I remember, years and years ago, your discussing with me how curiously easily plants get naturalised on uninhabited islands, if ships even touch there. I remember we discussed packages being opened with old hay or straw, etc. Now think of hides and wool (and wool exported largely over Europe), and plants introduced, and samples of corn; and I must think that if Australia had been the old country, and Europe had been the Botany Bay, very few, very much fewer, Australian plants would have run wild in Europe than have now in Australia. The case seems to me much stronger between La Plata and Spain. Nevertheless, I will put in my one sentence on this head, illustrating the greater migration during Glacial period from north to south than reversely, very humbly and cautiously. (343/4. "Origin of Species," Edition I., page 379. Darwin refers to the facts given by Hooker and De Candolle showing a stronger migratory flow from north to south than in the opposite direction. Darwin accounts for this by the northern plants having been long subject to severe competition in their northern homes, and having acquired a greater "dominating power" than the southern forms. "Just in the same manner as we see at the present day that very many European productions cover the ground in La Plata, and in a lesser degree in Australia, and have to a certain extent beaten the natives; whereas extremely few southern forms have become naturalised in any part of Europe, though hides, wool, and other objects likely to carry seeds have been largely imported during the last two or three centuries from La Plata, and during the last thirty or forty years from Australia.') I am very glad to hear you are making good progress with your Australian Introduction. I am, thank God, more than half through my chapter on geographical distribution, and have done the abstract of the Glacial part... LETTER 344. TO J.D. HOOKER. Down, March 30th, 1859. Many thanks for your agreeable note. Please keep the geographical MS. till you hear from me, for I may have to beg you to send it to Murray; as through Lyell's intervention I hope he will publish, but he requires first to see MS. (344/1. "The Origin of Species"; see a letter to Lyell in "Life and Letters," II., page 151.) I demur to what you say that we change climate of the world to account for "migration of bugs, flies, etc." WE do nothing of the sort; for WE rest on scored rocks, old moraines, arctic shells, and mammifers. I have no theory whatever about cause of cold, no more than I have for cause of elevation and subsidence; and I can see no reason why I should not use cold, or elevation, or subsidence to explain any other phenomena, such as distribution. I think if I had space and time I could make a pretty good case against any great continental changes since the Glacial epoch, and this has mainly led me to give up the Lyellian doctrine as insufficient to explain all mutations of climate. I was amused at the British Museum evidence. (344/2. This refers to the letter to Murchison (Letter 65), published with the evidence of the 1858 enquiry by the Trustees of the British Museum.) I am made to give my opinion so authoritatively on botanical matters!... As for our belief in the origin of species making any difference in descriptive work, I am sure it is incorrect, for I did all my barnacle work under this point of view. Only I often groaned that I was not allowed simply to decide whether a difference was sufficient to deserve a name. I am glad to hear about Huxley--a wonderful man. LETTER 345. TO J.D. HOOKER. Wells Terrace, Ilkley, Otley, Yorkshire, Thursday [before December 9th, 1859]. I have read your discussion (345/1. See "Introductory Essay," page c. Darwin did not receive this work until December 23rd, so that the reference is to proof-sheets.), as usual, with great interest. The points are awfully intricate, almost at present beyond the confines of knowledge. The view which I should have looked at as perhaps most probable (though it hardly differs from yours) is that the whole world during the Secondary ages was inhabited by marsupials, araucarias (Mem.--Fossil wood so common of this nature in South America (345/2. See Letter 6, Note.)), Banksia, etc.; and that these were supplanted and exterminated in the greater area of the north, but were left alive in the south. Whence these very ancient forms originally proceeded seems a hopeless enquiry. Your remarks on the passage of the northern forms southward, and of the southern forms of no kinds passing northward, seem to me grand. Admirable, also, are your remarks on the struggle of vegetation: I find that I have rather misunderstood you, for I feared I differed from you, which I see is hardly the case at all. I cannot help suspecting that you put rather too much weight to climate in the case of Australia. La Plata seems to present such analogous facts, though I suppose the naturalisation of European plants has there taken place on a still larger scale than in Australia... You will get four copies of my book--one for self, and three for the foreign botanists--in about ten days, or sooner; i.e., as soon as the sheets can be bound in cloth. I hope this will not be too late for your parcels. When you read my volume, use your pencil and score, so that some time I may have a talk with you on any criticisms. LETTER 346. TO HUGH FALCONER. Down, December 17th, [1859]. Whilst I think of it, let me tell you that years ago I remember seeing in the Museum of the Geological Society a tooth of hippopotamus from Madagascar: this, on geographical and all other grounds, ought to be looked to. Pray make a note of this fact. (346/1. At a meeting of the Geological Society, May 1st, 1833, a letter was read from Mr. Telfair to Sir Alex. Johnstone, accompanying a specimen of recent conglomerate rock, from the island of Madagascar, containing fragments of a tusk, and part of a molar tooth of a hippopotamus ("Proc. Geol. Soc." 1833, page 479). There is a reference to these remains of hippopotamus in a paper by Mr. R.B. Newton in the "Geol. Mag." Volume X., 1893; and in Dr. Forsyth Major's memoir on Megaladapis Madagascariensis ("Phil. Trans. R. Soc." Volume 185, page 30, 1894). Since this letter was written, several bones belonging to two or possibly three species of hippopotamus have been found in Madagascar. See Forsyth Major, "On the General Results of a Zoological Expedition to Madagascar in 1894-96" ("Proc. Zool. Soc." 1896, page 971.)) We have returned a week ago from Ilkley, and it has done me some decided good. In London I saw Lyell (the poor man who has "rushed into the bosom of two heresies"--by the way, I saw his celts, and how intensely interesting), and he told me that you were very antagonistic to my views on species. I well knew this would be the case. I must freely confess, the difficulties and objections are terrific; but I cannot believe that a false theory would explain, as it seems to me it does explain, so many classes of facts. Do you ever see Wollaston? He and you would agree nicely about my book (346/2. "Origin of Species," 1859.)--ill luck to both of you. If you have anything at all pleasant for me to hear, do write; and if all that you can say is very unpleasant, it will do you good to expectorate. And it is well known that you are very fond of writing letters. Farewell, my good old friend and enemy. Do make a note about the hippopotamus. If you are such a gentleman as to write, pray tell me how Torquay agrees with your health. (PLATE: DR. ASA GRAY, 1867.) LETTER 347. TO ASA GRAY. Down, December 24th [1859]. I have been for ten weeks at Water-cure, and on my return a fortnight ago through London I found a copy of your Memoir, and heartily do I thank you for it. (347/1. "Diagnostic Characters of New Species of Phaenogamous Plants collected in Japan by Charles Wright...with Observations upon the Relations of the Japanese Flora to that of North America and of other parts of the Northern Temperate Zone" ("Mem. American Acad. Arts and Sci." Volume VI., page 377, 1857).) I have not read it, and shall not be able very soon, for I am much overworked, and my stomach has got nearly as bad as ever. With respect to the discussion on climate, I beg you to believe that I never put myself for a moment in competition with Dana; but when one has thought on a subject, one cannot avoid forming some opinion. What I wrote to Hooker I forget, after reading only a few sheets of your Memoir, which I saw would be full of interest to me. Hooker asked me to write to you, but, as I told him, I would not presume to express an opinion to you without careful deliberation. What he wrote I know not: I had previously several years ago seen (by whom I forget) some speculation on warmer period in the U. States subsequent to Glacial period; and I had consulted Lyell, who seemed much to doubt, and Lyell's judgment is really admirably cautious. The arguments advanced in your paper and in your letter seem to me hardly sufficient; not that I should be at all sorry to admit this subsequent and intercalated warmer period--the more changes the merrier, I think. On the other hand, I do not believe that introduction of the Old World forms into New World subsequent to the Glacial period will do for the modified or representative forms in the two Worlds. There has been too much change in comparison with the little change of isolated alpine forms; but you will see this in my book. (347/2. "Origin of Species" (1859), Chapter XI., pages 365 et seq.) I may just make a few remarks why at first sight I do not attach much weight to the argument in your letter about the warmer climate. Firstly, about the level of the land having been lower subsequently to Glacial period, as evidenced by the whole, etc., I doubt whether meteorological knowledge is sufficient for this deduction: turning to the S. hemisphere, it might be argued that a greater extent of water made the temperature lower; and when much of the northern land was lower, it would have been covered by the sea and intermigration between Old and New Worlds would have been checked. Secondly, I doubt whether any inference on nature of climate can be deduced from extinct species of mammals. If the musk-ox and deer of great size of your Barren-Grounds had been known only by fossil bones, who would have ventured to surmise the excessively cold climate they lived under? With respect to food of large animals, if you care about the subject will you turn to my discussion on this subject partly in respect to the Elephas primigenius in my "Journal of Researches" (Murray's Home and Colonial Library), Chapter V., page 85. (347/3. "The firm conviction of the necessity of a vegetation possessing a character of tropical luxuriance to support such large animals, and the impossibility of reconciling this with the proximity of perpetual congelation, was one chief cause of the several theories of sudden revolutions of climate...I am far from supposing that the climate has not changed since the period when these animals lived, which now lie buried in the ice. At present I only wish to show that as far as quantity of food alone is concerned, the ancient rhinoceroses might have roamed over the steppes of Central Siberia even in their present condition, as well as the living rhinoceroses and elephants over the karoos of Southern Africa" ("Journal of Researches," page 89, 1888).) In this country we infer from remains of Elephas primigenius that the climate at the period of its embedment was very severe, as seems countenanced by its woolly covering, by the nature of the deposits with angular fragments, the nature of the co-embedded shells, and co-existence of the musk-ox. I had formerly gathered from Lyell that the relative position of the Megatherium and Mylodon with respect to the Glacial deposits, had not been well made out; but perhaps it has been so recently. Such are my reasons for not as yet admitting the warmer period subsequent to Glacial epoch; but I daresay I may be quite wrong, and shall not be at all sorry to be proved so. I shall assuredly read your essay with care, for I have seen as yet only a fragment, and very likely some parts, which I could not formerly clearly understand, will be clear enough. LETTER 348. TO J.D. HOOKER. Down, [December] 26th, [1859]. I have just read with intense interest as far as page xxvi (348/1. For Darwin's impression of the "Introductory Essay to the Tasmanian Flora" as a whole, see "Life and Letters," II., page 257.), i.e. to where you treat of the Australian Flora itself; and the latter part I remember thinking most of in the proof-sheets. Either you have altered a good deal, or I did not see all or was purblind, for I have been much more interested with all the first part than I was before,--not that I did not like it at first. All seems to me very clearly written, and I have been baulked at only one sentence. I think, on the whole, I like the geological, or rather palaeontological, discussion best: it seems to me excellent, and admirably cautious. I agree with all that you say as far as my want of special knowledge allows me to judge. I have no criticisms of any importance, but I should have liked more facts in one or two places, which I shall not ask about. I rather demur to the fairness of your comparison of rising and sinking areas (348/2. Hooker, op. cit., page xv, paragraph 24. Hooker's view was that sinking islands "contain comparatively fewer species and fewer peculiar generic types than those which are rising." In Darwin's copy of the Essay is written on the margin of page xvi: "I doubt whole case."), as in the Indian Ocean you compare volcanic land with exclusively coral islands, and these latter are very small in area and have very peculiar soil, and during their formation are likely to have been utterly submerged, perhaps many times, and restocked with existing plants. In the Pacific, ignorance of Marianne and Caroline and other chief islands almost prevent comparison (348/3. Gambier Island would be an interesting case. [Note in original.]); and is it right to include American islands like Juan Fernandez and Galapagos? In such lofty and probably ancient islands as Sandwich and Tahiti it cannot make much difference in the flora whether they have sunk or risen a few thousand feet of late ages. I wish you could work in your notion of certain parts of the Tropics having kept hot, whilst other parts were cooled; I tried this scheme in my mind, and it seemed to fail. On the whole, I like very much all that I have read of your Introduction, and I cannot doubt that it will have great weight in converting other botanists from the doctrine of immutable creation. What a lot of matter there is in one of your pages! There are many points I wish much to discuss with you. How I wish you could work out the Pacific floras: I remember ages ago reading some of your MS. In Paris there must be, I should think, materials from French voyages. But of all places in the world I should like to see a good flora of the Sandwich Islands. (348/4. See Hillebrand, "Flora of the Hawaiian Islands," 1888.) I would subscribe 50 pounds to any collector to go there and work at the islands. Would it not pay for a collector to go there, especially if aided by any subscription? It would be a fair occasion to ask for aid from the Government grant of the Royal Society. I think it is the most isolated group in the world, and the islands themselves well isolated from each other. LETTER 349. TO ASA GRAY. Down, January 7th [1860]. I have just finished your Japan memoir (349/1. "Diagnostic Characters of New Species of Phaenogamous Plants collected in Japan by Charles Wright. With observations upon the Relations of the Japanese Flora to that of North America, etc.: 1857-59."--"Memoirs of Amer. Acad." VI.), and I must thank you for the extreme interest with which I have read it. It seems to me a most curious case of distribution; and how very well you argue, and put the case from analogy on the high probability of single centres of creation. That great man Agassiz, when he comes to reason, seems to me as great in taking a wrong view as he is great in observing and classifying. One of the points which has struck me as most remarkable and inexplicable in your memoir is the number of monotypic (or nearly so) genera amongst the representative forms of Japan and N. America. And how very singular the preponderance of identical and representative species in Eastern, compared with Western, America. I have no good map showing how wide the moderately low country is on the west side of the Rocky Mountains; nor, of course, do I know whether the whole of the low western territory has been botanised; but it has occurred to me, looking at such maps as I have, that the eastern area must be larger than the western, which would account to a certain small extent for preponderance on eastern side of the representative species. Is there any truth in this suspicion? Your memoir sets me marvelling and reflecting. I confess I am not able quite to understand your Geology at pages 447, 448; but you would probably not care to hear my difficulties, and therefore I will not trouble you with them. I was so grieved to get a letter from Dana at Florence, giving me a very poor (though improved) account of his health. LETTER 350. TO T.H. HUXLEY. 15, Marine Parade, Eastbourne, November 1st [1860]. Your note has been wonderfully interesting. Your term, "pithecoid man," is a whole paper and theory in itself. How I hope the skull of the new Macrauchenia has come. It is grand. I return Hooker's letter, with very many thanks. The glacial action on Lebanon is particularly interesting, considering its position between Europe and Himalaya. I get more and more convinced that my doctrine of mundane Glacial period is correct (350/1. In the 1st edition of the "Origin," page 373, Darwin argues in favour of a Glacial period practically simultaneous over the globe. In the 5th edition, 1869, page 451, he adopted Mr. Croll's views on the alternation of cold periods in the northern and southern hemispheres. An interesting modification of the mundane Glacial period theory is given in Belt's "The Naturalist in Nicaragua," 1874, page 265. Mr. Belt's views are discussed in Wallace's "Geogr. Distribution," 1876, Volume I., page 151.), and that it is the most important of all late phenomena with respect to distribution of plants and animals. I hope your Review (350/2. The history of the foundation of the "Natural History Review" is given in Huxley's "Life and Letters," Volume I., page 209. See Letter 107.) progresses favourably. I am exhausted and not well, so write briefly; for we have had nine days of as much misery as man can endure. My poor daughter has suffered pitiably, and night and day required three persons to support her. The crisis of extreme danger is over, and she is rallying surprisingly, but the doctors are yet doubtful of ultimate issue. But the suffering was so pitiable I almost got to wish to see her die. She is easy now. When she will be fit to travel home I know not. I most sincerely hope that Mrs. Huxley keeps up pretty well. The work which most men have to do is a blessing to them in such cases as yours. God bless you. Sir H. Holland came here to see her, and was wonderfully kind. LETTER 351. TO C. LYELL. Down, November 20th [1860]. I quite agree in admiration of Forbes' Essay (351/1. "Memoir of the Geolog. Survey of the United Kingdom," Volume I., 1846.), yet, on my life, I think it has done, in some respects, as much mischief as good. Those who believe in vast continental extensions will never investigate means of distribution. Good heavens, look at Heer's map of Atlantis! I thought his division and lines of travel of the British plants very wild, and with hardly any foundation. I quite agree with what you say of almost certainty of Glacial epoch having destroyed the Spanish saxifrages, etc., in Ireland. (351/2. See Letter 20.) I remember well discussing this with Hooker; and I suggested that a slightly different or more equable and humid climate might have allowed (with perhaps some extension of land) the plants in question to have grown along the entire western shores between Spain and Ireland, and that subsequently they became extinct, except at the present points under an oceanic climate. The point of Devonshire now has a touch of the same character. I demur in this particular case to Forbes' transportal by ice. The subject has rather gone out of my mind, and it is not worth looking to my MS. discussion on migration during the Glacial period; but I remember that the distribution of mammalia, and the very regular relation of the Alpine plants to points due north (alluded to in "Origin"), seemed to indicate continuous land at close of Glacial period. LETTER 352. TO J.D. HOOKER. Down, March 18th [1861]. I have been recalling my thoughts on the question whether the Glacial period affected the whole world contemporaneously, or only one longitudinal belt after another. To my sorrow my old reasons for rejecting the latter alternative seem to me sufficient, and I should very much like to know what you think. Let us suppose that the cold affected the two Americas either before or after the Old World. Let it advance first either from north or south till the Tropics became slightly cooled, and a few temperate forms reached the Silla of Caracas and the mountains of Brazil. You would say, I suppose, that nearly all the tropical productions would be killed; and that subsequently, after the cold had moderated, tropical plants immigrated from the other non-chilled parts of the world. But this is impossible unless you bridge over the tropical parts of the Atlantic--a doctrine which you know I cannot admit, though in some respects wishing I could. Oswald Heer would make nothing of such a bridge. When the Glacial period affected the Old World, would it not be rather rash to suppose that the meridian of India, the Malay Archipelago, and Australia were refrigerated, and Africa not refrigerated? But let us grant that this was so; let us bridge over the Red Sea (though rather opposed to the former almost certain communication between the Red Sea and the Mediterranean); let us grant that Arabia and Persia were damp and fit for the passage of tropical plants: nevertheless, just look at the globe and fancy the cold slowly coming on, and the plants under the tropics travelling towards the equator, and it seems to me highly improbable that they could escape from India to the still hot regions of Africa, for they would have to go westward with a little northing round the northern shores of the Indian Ocean. So if Africa were refrigerated first, there would be considerable difficulty in the tropical productions of Africa escaping into the still hot regions of India. Here again you would have to bridge over the Indian Ocean within so very recent a period, and not in the line of the Laccadive Archipelago. If you suppose the cold to travel from the southern pole northwards, it will not help us, unless we suppose that the countries immediately north of the northern tropic were at the same time warmer, so as to allow free passage from India to Africa, which seems to me too complex and unsupported an hypothesis to admit. Therefore I cannot see that the supposition of different longitudinal belts of the world being cooled at different periods helps us much. The supposition of the whole world being cooled contemporaneously (but perhaps not quite equally, South America being less cooled than the Old World) seems to me the simplest hypothesis, and does not add to the great difficulty of all the tropical productions not having been exterminated. I still think that a few species of each still existing tropical genus must have survived in the hottest or most favourable spots, either dry or damp. The tropical productions, though much distressed by the fall of temperature, would still be under the same conditions of the length of the day, etc., and would be still exposed to nearly the same enemies, as insects and other animals; whereas the invading temperate productions, though finding a favouring temperature, would have some of their conditions of life new, and would be exposed to many new enemies. But I fully admit the difficulty to be very great. I cannot see the full force of your difficulty of no known cause of a mundane change of temperature. We know no cause of continental elevations and depressions, yet we admit them. Can you believe, looking to Europe alone, that the intense cold, which must have prevailed when such gigantic glaciers extended on the plains of N. Italy, was due merely to changed positions of land within so recent a period? I cannot. It would be far too long a story, but it could, I think, be clearly shown that all our continents existed approximately in their present positions long before the Glacial period; which seems opposed to such gigantic geographical changes necessary to cause such a vast fall of temperature. The Glacial period endured in Europe and North America whilst the level of the land oscillated in height fully 3,000 feet, and this does not look as if changed level was the cause of the Glacial period. But I have written an unreasonably long discussion. Do not answer me at length, but send me a few words some time on the subject. I have had this copied, that it might not bore you too much to read it. A few words more. When equatorial productions were dreadfully distressed by fall of temperature, and probably by changed humidity, and changed proportional numbers of other plants and enemies (though they might favour some of the species), I must admit that they all would be exterminated if productions exactly fitted, not only for the climate, but for all the conditions of the equatorial regions during the Glacial period existed and could everywhere have immigrated. But the productions of the temperate regions would have probably found, under the equator, in their new homes and soils, considerably different conditions of humidity and periodicity, and they would have encountered a new set of enemies (a most important consideration); for there seems good reason to believe that animals were not able to migrate nearly to the extent to which plants did during the Glacial period. Hence I can persuade myself that the temperate productions would not entirely replace and exterminate the productions of the cooled tropics, but would become partially mingled with them. I am far from satisfied with what I have scribbled. I conclude that there must have been a mundane Glacial period, and that the difficulties are much the same whether we suppose it contemporaneous over the world, or that longitudinal belts were affected one after the other. For Heaven's sake forgive me! LETTER 353. TO H.W. BATES. March 26th [1861]. I have been particularly struck by your remarks on the Glacial period. (353/1. In his "Contributions to the Insect Fauna of the Amazon Valley," "Trans. Entom. Soc." Volume V., page 335 (read November 24th, 1860), Mr. Bates discusses the migration of species from the equatorial regions after the Glacial period. He arrives at a result which, he points out, "is highly interesting as bearing upon the question of how far extinction is likely to have occurred in equatorial regions during the time of the Glacial epoch."..."The result is plain, that there has always (at least throughout immense geological epochs) been an equatorial fauna rich in endemic species, and that extinction cannot have prevailed to any extent within a period of time so comparatively modern as the Glacial epoch in geology." This conclusion does not support the view expressed in the "Origin of Species" (Edition I., chapter XI., page 378) that the refrigeration of the earth extended to the equatorial regions. (Bates, loc. cit., pages 352, 353.)) You seem to me to have put the case with admirable clearness and with crushing force. I am quite staggered with the blow, and do not know what to think. Of late several facts have turned up leading me to believe more firmly that the Glacial period did affect the equatorial regions; but I can make no answer to your argument, and am completely in a cleft stick. By an odd chance I have only a few days ago been discussing this subject, in relation to plants, with Dr. Hooker, who believes to a certain extent, but strongly urged the little apparent extinction in the equatorial regions. I stated in a letter some days ago to him that the tropics of S. America seem to have suffered less than the Old World. There are many perplexing points; temperate plants seem to have migrated far more than animals. Possibly species may have been formed more rapidly within tropics than one would have expected. I freely confess that you have confounded me; but I cannot yet give up my belief that the Glacial period did to certain extent affect the tropics. LETTER 354. TO J.D. HOOKER. Down, February 25th [1862]. I have almost finished your Arctic paper, and I must tell you how I admire it. (354/1. "Outlines of the Distribution of Arctic Plants" [Read June 21st, 1860], "Linn. Soc. Trans." XXIII., 1862, page 251. The author's remarks on Mr. Darwin's theories of Geographical Distribution are given at page 255: they are written in a characteristically generous spirit.) The subject, treated as you have treated it, is really magnificent. Good Heaven, what labour it must have cost you! And what a grand prospect there is for the future. I need not say how much pleased I am at your notice of my work; for you know that I regard your opinion more than that of all others. Such papers are the real engine to compel people to reflect on modification of species; any one with an enquiring mind could hardly fail to wish to consider the whole subject after reading your paper. By Jove! you will be driven, nolens volens, to a cooled globe. Think of your own case of Abyssinia and Fernando Po, and South Africa, and of your Lebanon case (354/2. See "Origin," Edition VI., page 337.); grant that there are highlands to favour migration, but surely the lowlands must have been somewhat cooled. What a splendid new and original evidence and case is that of Greenland: I cannot see how, even by granting bridges of continuous land, one can understand the existing flora. I should think from the state of Scotland and America, and from isothermals, that during the coldest part of Glacial period, Greenland must have been quite depopulated. Like a dog to his vomit, I cannot help going back and leaning to accidental means of transport by ice and currents. How curious also is the case of Iceland. What a splendid paper you have made of the subject. When we meet I must ask you how much you attribute richness of flora of Lapland to mere climate; it seems to me very marvellous that this point should have been a sort of focus of radiation; if, however, it is unnaturally rich, i.e. contains more species than it ought to do for its latitude, in comparison with the other Arctic regions, would it not thus falsely seem a focus of radiation? But I shall hereafter have to go over and over again your paper; at present I am quite muddy on the subject. How very odd, on any view, the relation of Greenland to the mountains of E. N. America; this looks as if there had been wholesale extinction in E. N. America. But I must not run on. By the way, I find Link in 1820 speculated on relation of Alpine and Arctic plants being due to former colder climate, which he attributed to higher mountains cutting off the warm southern winds. LETTER 355. J.D. HOOKER TO CHARLES DARWIN. Kew, November 2nd, 1862. Did I tell you how deeply pleased I was with Gray's notice of my Arctic essay? (355/1. "American Journal of Science and Arts," XXXIV., and in Gray's "Scientific Papers," Volume I., page 122.) It was awfully good of him, for I am sure he must have seen several blunders. He tells me that Dr. Dawson (355/2. A letter (No. 144) by Sir J.D. Hooker, dated November 7th, 1862, on this subject occurs in the Evolutionary section.) is down on me, and I have a very nice lecture on Arctic and Alpine plants from Dr. D., with a critique on the Arctic essay--which he did not see till afterwards. He has found some mares' nests in my essay, and one very venial blunder in the tables--he seems to HATE Darwinism--he accuses me of overlooking the geological facts, and dwells much on my overlooking subsidence of temperate America during Glacial period--and my asserting a subsidence of Arctic America, which never entered into my head. I wish, however, if it would not make your head ache too much, you would just look over my first three pages, and tell me if I have outraged any geological fact or made any oversights. I expounded the whole thing twice to Lyell before I printed it, with map and tables, intending to get (and I thought I had) his imprimatur for all I did and said; but when here three nights ago, I found he was as ignorant of my having written an Arctic essay as could be! And so I suppose he either did not take it in, or thought it of little consequence. Hector approved of it in toto. I need hardly say that I set out on biological grounds, and hold myself as independent of theories of subsidence as you do of the opinions of physicists on heat of globe! I have written a long [letter] to Dawson. By the way, did you see the "Athenaeum" notice of L. Bonaparte's Basque and Finnish language?--is it not possible that the Basques are Finns left behind after the Glacial period, like the Arctic plants? I have often thought this theory would explain the Mexican and Chinese national affinities. I am plodding away at Welwitschia by night and Genera Plantarum by day. We had a very jolly dinner at the Club on Thursday. We are all well. LETTER 356. TO J.D. HOOKER. Down, November 4th [1862]. I have read the pages (356/1. The paper on Arctic plants in Volume XXIII. of the Linnean Society's "Transactions," 1860-62.) attentively (with even very much more admiration than the first time) and cannot imagine what makes Dr. D. accuse you of asserting a subsidence of Arctic America. (356/2. The late Sir J.W. Dawson wrote a review (signed J.W.D) of Hooker's Arctic paper which appeared in the "Canadian Naturalist," 1862, Volume VII., page 334. The chief part of the article is made up of quotations from Asa Gray's article referred to below. The remainder is a summary of geological arguments against Hooker's views. We do not find the accusation referred to above, which seems to have appeared in a lecture.) No doubt there was a subsidence of N. America during the Glacial period, and over a large part, but to maintain that the subsidence extended over nearly the whole breadth of the continent, or lasted during the whole Glacial period, I do not believe he can support. I suspect much of the evidence of subsidence during the Glacial period there will prove false, as it largely rests on ice-action, which is becoming, as you know, to be viewed as more and more subaerial. If Dawson has published criticisms I should like to see them. I have heard he is rabid against me, and no doubt partly in consequence, against anything you write in my favour (and never was anything published more favourable than the Arctic paper). Lyell had difficulty in preventing Dawson reviewing the "Origin" (356/3. Dawson reviewed the "Origin" in the "Canadian Naturalist," 1860.) on hearsay, without having looked at it. No spirit of fairness can be expected from so biassed a judge. All I can say is that your few first pages have impressed me far more this reading than the first time. Can the Scandinavian portion of the flora be so potent (356/4. Dr. Hooker wrote: "Regarded as a whole the Arctic flora is decidedly Scandinavian; for Arctic Scandinavia, or Lapland, though a very small tract of land, contains by far the richest Arctic flora, amounting to three-fourths of the whole"; he pointed out "that the Scandinavian flora is present in every latitude of the globe, and is the only one that is so" (quoted by Gray, loc. cit. infra).) from having been preserved in that corner, warmed by the Gulf Stream, and from now alone representing the entire circumpolar flora, during the warmer pre-Glacial period? From the first I have not been able to resist the impression (shared by Asa Gray, whose Review (356/5. Asa Gray's "Scientific Papers," Volume I., page 122.) on you pleased me much) that during the Glacial period there must have been almost entire extinction in Greenland; for depth of sea does not favour former southerly extension of land there. (356/6. In the driving southward of the vegetation by the Glacial epoch the Greenland flora would be "driven into the sea, that is, exterminated." (Hooker quoted by Gray, loc. cit. page 124.) I must suspect that plants have been largely introduced by sea currents, which bring so much wood from N. Europe. But here we shall split as wide as the poles asunder. All the world could not persuade me, if it tried, that yours is not a grand essay. I do not quite understand whether it is this essay that Dawson has been "down on." What a curious notion about Glacial climate, and Basques and Finns! Are the Basques mountaineers--I hope so. I am sorry I have not seen the "Athenaeum," but I now take in the "Parthenon." By the way, I have just read with much interest Max Muller (356/7. Probably his "Lectures on the Science of Language," 1861-64.); the last part, about first origin of language, seems the least satisfactory part. Pray thank Oliver heartily for his heap of references on poisons. (356/8. Doubtless in connection with Darwin's work on Drosera: he was working at this subject during his stay at Bournemouth in the autumn of 1862.) How the devil does he find them out? I must not indulge [myself] with Cypripedium. Asa Gray has made out pretty clearly that, at least in some cases, the act of fertilisation is effected by small insects being forced to crawl in and out of the flower in a particular direction; and perhaps I am quite wrong that it is ever effected by the proboscis. I retract so far that if you have the rare C. hirsutissimum, I should very much like to examine a cut single flower; for I saw one at a flower show, and as far as I could see, it seemed widely different from other forms. P.S.--Answer this, if by chance you can. I remember distinctly having read in some book of travels, I am nearly sure in Australia, an account of the natives, during famines, trying and cooking in all sorts of ways various vegetable productions, and sometimes being injured by them. Can you remember any such account? I want to find it. I thought it was in Sir G. Grey, but it is not. Could it have been in Eyre's book? LETTER 357. J.D. HOOKER TO CHARLES DARWIN. [November 1862]. ...I have speculated on the probability of there having been a post-Glacial Arctic-Norwego-Greenland in connection, which would account for the strong fact, that temperate Greenland is as Arctic as Arctic Greenland is--a fact, to me, of astounding force. I do confess, that a northern migration would thus fill Greenland as it is filled, in so far as the whole flora (temperate and Arctic) would be Arctic,--but then the same plants should have gone to the other Polar islands, and above all, so many Scandinavian Arctic plants should not be absent in Greenland, still less should whole Natural Orders be absent, and above all the Arctic Leguminosae. It is difficult (as I have told Dawson) to conceive of the force with which arguments drawn from the absence of certain familiar ubiquitous plants strike the botanists. I would not throw over altogether ice-transport and water-transport, but I cannot realise their giving rise to such anomalies, in the distribution, as Greenland presents. So, too, I have always felt the force of your objection, that Greenland should have been depopulated in the Glacial period, but then reflected that vegetation now ascends I forget how high (about 1,000 feet) in Disco, in 70 deg, and that even in a Glacial ocean there may always have been lurking-places for the few hundred plants Greenland now possesses. Supposing Greenland were repeopled from Scandinavia over ocean way, why should Carices be the chief things brought? Why should there have been no Leguminosae brought, no plants but high Arctic?--why no Caltha palustris, which gilds the marshes of Norway and paints the housetops of Iceland? In short, to my eyes, the trans-oceanic migration would no more make such an assemblage than special creations would account for representative species--and no "ingenious wriggling" ever satisfied me that it would. There, then! I dined with Henry Christy last night, who was just returned from celt hunting with Lartet, amongst the Basques,--they are Pyreneans. Lubbock was there, and told me that my precious speculation was one of Von Baer's, and that the Finns are supposed to have made the Kjokken moddings. I read Max Muller a year ago--and quite agree, first part is excellent; last, on origin of language, fatuous and feeble as a scientific argument. LETTER 358. TO J.D. HOOKER. Down, November 12th [1862]. I return by this post Dawson's lecture, which seems to me interesting, but with nothing new. I think he must be rather conceited, with his "If Dr. Hooker had known this and that, he would have said so and so." It seems to me absurd in Dawson assuming that North America was under sea during the whole Glacial period. Certainly Greenland is a most curious and difficult problem. But as for the Leguminosae, the case, my dear fellow, is as plain as a pike-staff, as the seeds are so very quickly killed by the sea-water. Seriously, it would be a curious experiment to try vitality in salt water of the plants which ought to be in Greenland. I forget, however, that it would be impossible, I suppose, to get hardly any except the Caltha, and if ever I stumble on that plant in seed I will try it. I wish to Heaven some one would examine the rocks near sea-level at the south point of Greenland, and see if they are well scored; that would tell something. But then subsidence might have brought down higher rocks to present sea-level. I am much more willing to admit your Norwego-Greenland connecting land than most other cases, from the nature of the rocks in Spitzbergen and Bear Island. You have broached and thrown a lot of light on a splendid problem, which some day will be solved. It rejoices me to think that, when a boy, I was shown an erratic boulder in Shrewsbury, and was told by a clever old gentleman that till the world's end no one would ever guess how it came there. It makes me laugh to think of Dr. Dawson's indignation at your sentence about "obliquity of vision." (358/1. See Letter 144.) By Jove, he will try and pitch into you some day. Good night for the present. To return for a moment to the Glacial period. You might have asked Dawson whether ibex, marmot, etc., etc., were carried from mountain to mountain in Europe on floating ice; and whether musk ox got to England on icebergs? Yet England has subsided, if we trust to the good evidence of shells alone, more during Glacial period than America is known to have done. For Heaven's sake instil a word of caution into Tyndall's ears. I saw an extract that valleys of Switzerland were wholly due to glaciers. He cannot have reflected on valleys in tropical countries. The grandest valleys I ever saw were in Tahiti. Again, if I understand, he supposes that glaciers wear down whole mountain ranges; thus lower their height, decrease the temperature, and decrease the glaciers themselves. Does he suppose the whole of Scotland thus worn down? Surely he must forget oscillation of level would be more potent one way or another during such enormous lapses of time. It would be hard to believe any mountain range has been so long stationary. I suppose Lyell's book will soon be out. (358/2. "The Antiquity of Man," 1863.) I was very glad to see in a newspaper that Murray sold 4,000. What a sale! I am now working on cultivated plants, and rather like my work; but I am horribly afraid I make the rashest remarks on value of differences. I trust to a sort of instinct, and, God knows, can seldom give any reason for my remarks. Lord, in what a medley the origin of cultivated plants is. I have been reading on strawberries, and I can find hardly two botanists agree what are the wild forms; but I pick out of horticultural books here and there queer cases of variation, inheritance, etc., etc. What a long letter I have scribbled; but you must forgive me, for it is a great pleasure thus talking to you. Did you ever hear of "Condy's Ozonised Water"? I have been trying it with, I think, extraordinary advantage--to comfort, at least. A teaspoon, in water, three or four times a day. If you meet any poor dyspeptic devil like me, suggest it. LETTER 359. TO J.D. HOOKER. Down, 26th [March 1863]. I hope and think you are too severe on Lyell's early chapters. Though so condensed, and not well arranged, they seemed to me to convey with uncommon force the antiquity of man, and that was his object. (359/1. "The Geological Evidences of the Antiquity of Man": London, 1863.) It did not occur to me, but I fear there is some truth in your criticism, that nothing is to be trusted until he [Lyell] had observed it. I am glad to see you stirred up about tropical plants during Glacial period. Remember that I have many times sworn to you that they coexisted; so, my dear fellow, you must make them coexist. I do not think that greater coolness in a disturbed condition of things would be required than the zone of the Himalaya, in which you describe some tropical and temperate forms commingling (359/2. "During this [the Glacial period], the coldest point, the lowlands under the equator, must have been clothed with a mingled tropical and temperate vegetation, like that described by Hooker as growing luxuriantly at the height of from four to five thousand feet on the lower slopes of the Himalaya, but with perhaps a still greater preponderance of temperate forms" ("Origin of Species," Edition VI., page 338).); and as in the lower part of the Cameroons, and as Seemann describes, in low mountains of Panama. It is, as you say, absurd to suppose that such a genus as Dipterocarpus (359/3. Dipterocarpus, a genus of the Dipterocarpaceae, a family of dicotyledonous plants restricted to the tropics of the Old World.) could have been developed since the Glacial era; but do you feel so sure, as to oppose (359/4. The meaning seems to be: "Do you feel so sure that you can bring in opposition a large body of considerations to show, etc.") a large body of considerations on the other side, that this genus could not have been slowly accustomed to a cooler climate? I see Lindley says it has not been brought to England, and so could not have been tried in the greenhouse. Have you materials to show to what little height it ever ascends the mountains of Java or Sumatra? It makes a mighty difference, the whole area being cooled; and the area perhaps not being in all respects, such as dampness, etc., etc., fitted for such temperate plants as could get in. But, anyhow, I am ready to swear again that Dipterocarpus and any other genus you like to name did survive during a cooler period. About reversion you express just what I mean. I somehow blundered, and mentally took literally that the child inherited from his grandfather. This view of latency collates a lot of facts--secondary sexual characters in each individual; tendency of latent character to appear temporarily in youth; effect of crossing in educing talent, character, etc. When one thinks of a latent character being handed down, hidden for a thousand or ten thousand generations, and then suddenly appearing, one is quite bewildered at the host of characters written in invisible ink on the germ. I have no evidence of the reversion of all characters in a variety. I quite agree to what you say about genius. I told Lyell that passage made me groan. What a pity about Falconer! (359/5. This refers to Falconer's claim of priority against Lyell. See "Life and Letters," III., page 14; also Letters 166 and 168.) How singular and how lamentable! Remember orchid pods. I have a passion to grow the seeds (and other motives). I have not a fact to go on, but have a notion (no, I have a firm conviction!) that they are parasitic in early youth on cryptogams! (359/6. In an article on British Epiphytal Orchids ("Gard. Chron." 1884, page 144) Malaxis paludosa is described by F.W. Burbidge as being a true epiphyte on the stems of Sphagnum. Stahl states that the difficulty of cultivating orchids largely depends on their dependence on a mycorhizal fungus,--though he does not apply his view to germination. See Pringsheim's "Jahrbucher," XXXIV., page 581. We are indebted to Sir Joseph Hooker for the reference to Burbidge's paper.) Here is a fool's notion. I have some planted on Sphagnum. Do any tropical lichens or mosses, or European, withstand heat, or grow on any trees in hothouse at Kew? If so, for love of Heaven, favour my madness, and have some scraped off and sent me. I am like a gambler, and love a wild experiment. It gives me great pleasure to fancy that I see radicles of orchid seed penetrating the Sphagnum. I know I shall not, and therefore shall not be disappointed. LETTER 360. TO J.D. HOOKER. Down [September 26th 1863]. ...About New Zealand, at last I am coming round, and admit it must have been connected with some terra firma, but I will die rather than admit Australia. How I wish mountains of New Caledonia were well worked!... LETTER 361. TO J.D. HOOKER. (361/1. In the earlier part of this letter Mr. Darwin refers to a review on Planchon in the "Nat. History Review," April 1865. There can be no doubt, therefore, that "Thomson's article" must be the review of Jordan's "Diagnoses d'especes nouvelles ou meconnues," etc., in the same number, page 226. It deals with "lumpers" and "splitters," and a possible trinomial nomenclature.) April 17th [1865]. I have been very much struck by Thomson's article; it seems to me quite remarkable for its judgment, force, and clearness. It has interested me greatly. I have sometimes loosely speculated on what nomenclature would come to, and concluded that it would be trinomial. What a name a plant will formally bear with the author's name after genus (as some recommend), and after species and subspecies! It really seems one of the greatest questions which can be discussed for systematic Natural History. How impartially Thomson adjusts the claims of "hair-splitters" and "lumpers"! I sincerely hope he will pretty often write reviews or essays. It is an old subject of grief to me, formerly in Geology and of late in Zoology and Botany, that the very best men (excepting those who have to write principles and elements, etc.) read so little, and give up nearly their whole time to original work. I have often thought that science would progress more if there was more reading. How few read any long and laborious papers! The only use of publishing such seems to be as a proof that the author has given time and labour to his work. LETTER 362. TO J.D. HOOKER. Down, October 22nd and 28th, 1865. As for the anthropologists being a bete noire to scientific men, I am not surprised, for I have just skimmed through the last "Anthrop. Journal," and it shows, especially the long attack on the British Association, a curious spirit of insolence, conceit, dullness, and vulgarity. I have read with uncommon interest Travers' short paper on the Chatham Islands. (362/1. See Travers, H.H., "Notes on the Chatham Islands," "Linn. Soc. Journ." IX., October 1865. Mr. Travers says he picked up a seed of Edwardsia, evidently washed ashore. The stranded logs indicated a current from New Zealand.) I remember your pitching into me with terrible ferocity because I said I thought the seed of Edwardsia might have been floated from Chili to New Zealand: now what do you say, my young man, to the three young trees of the same size on one spot alone of the island, and with the cast-up pod on the shore? If it were not for those unlucky wingless birds I could believe that the group had been colonised by accidental means; but, as it is, it appears by far to me the best evidence of continental extension ever observed. The distance, I see, is 360 miles. I wish I knew whether the sea was deeper than between New Zealand and Australia. I fear you will not admit such a small accident as the wingless birds having been transported on icebergs. Do suggest, if you have a chance, to any one visiting the Islands again, to look out for erratic boulders there. How curious his statement is about the fruit-trees and bees! (362/2. "Since the importation of bees, European fruit-trees and bushes have produced freely." Travers, "Linn. Soc. Journal," IX., page 144.) I wish I knew whether the clover had spread before the bees were introduced... I saw in the "Gardeners' Chronicle" the sentence about the "Origin" dying in Germany, but did not know it was by Seemann. LETTER 363. TO C. LYELL. Down, February 7th [1866]. I am very much obliged for your note and the extract, which have interested me extremely. I cannot disbelieve for a moment Agassiz on Glacial action after all his experience, as you say, and after that capital book with plates which he early published (363/1. "Etudes sur les Glaciers"; Neuchatel, 1840.); as for his inferences and reasoning on the valley of the Amazon that is quite another question, nor can he have seen all the regions to which Mrs. A. alludes. (363/2. A letter from Mrs. Agassiz to Lady Lyell, which had been forwarded to Mr. Darwin. The same letter was sent also to Sir Charles Bunbury, who, in writing to Lyell on February 3rd, 1866, criticises some of the statements. He speaks of Agassiz's observations on glacial phenomena in Brazil as "very astonishing indeed; so astonishing that I have very great difficulty in believing them. They shake my faith in the glacial system altogether; or perhaps they ought rather to shake the faith in Agassiz...If Brazil was ever covered with glaciers, I can see no reason why the whole earth should not have been so. Perhaps the whole terrestrial globe was once 'one entire and perfect icicle.'" (From the privately printed "Life" of Sir Charles Bunbury, edited by Lady Bunbury, Volume ii., page 334).) Her letter is not very clear to me, and I do not understand what she means by "to a height of more than three thousand feet." There are no erratic boulders (to which I particularly attended ) in the low country round Rio. It is possible or even probable that this area may have subsided, for I could detect no evidence of elevation, or any Tertiary formations or volcanic action. The Organ Mountains are from six to seven thousand feet in height; and I am only a little surprised at their bearing the marks of glacial action. For some temperate genera of plants, viz., Vaccinium, Andromeda, Gaultheria, Hypericum, Drosera, Habenaria, inhabit these mountains, and I look at this almost as good evidence of a cold period, as glacial action. That there are not more temperate plants can be accounted for by the isolated position of these mountains. There are no erratic boulders on the Pacific coast north of Chiloe, and but few glaciers in the Cordillera, but it by no means follows, I think, that there may not have been formerly gigantic glaciers on the eastern and more humid side. In the third edition of "Origin," page 403 (363/3. "Origin," Edition VI., page 335, 1882. "Mr. D. Forbes informs me that he found in various parts of the Cordillera, from lat. 13 deg W. to 30 deg S., at about the height of twelve thousand feet, deeply furrowed rocks...and likewise great masses of detritus, including grooved pebbles. Along this whole space of the Cordillera true glaciers do not now exist, even at much more considerable height. "), you will find a brief allusion, on authority of Mr. D. Forbes, on the former much lower extension of glaciers in the equatorial Cordillera. Pray also look at page 407 at what I say on the nature of tropical vegetation (which I could now much improve) during the Glacial period. (363/4. "During this, the coldest period, the lowlands under the Equator must have been clothed with a mingled tropical and temperate vegetation..." ("Origin," Edition VI., 1882, page 338).) I feel a strong conviction that soon every one will believe that the whole world was cooler during the Glacial period. Remember Hooker's wonderful case recently discovered of the identity of so many temperate plants on the summit of Fernando Po, and on the mountains of Abyssinia. (363/5. "Dr. Hooker has also lately shown that several of the plants living in the upper parts of the lofty island of Fernando Po, and in the neighbouring Cameroon Mountains, in the Gulf of Guinea, are closely related to those on the mountains of Abyssinia, and likewise to those of temperate Europe" (loc. cit., page 337).) I look at [it] as certain that these plants crossed the whole of Africa from east to west during the same period. I wish I had published a long chapter written in full, and almost ready for the press, on this subject, which I wrote ten years ago. It was impossible in the "Origin" to give a fair abstract. My health is considerably improved, so that I am able to work nearly two hours a day, and so make some little progress with my everlasting book on domestic varieties. You will have heard of my sister Catherine's easy death last Friday morning. (363/6. Catherine Darwin died in February 1866.) She suffered much, and we all look at her death as a blessing, for there was much fear of prolonged and greater suffering. We are uneasy about Susan, but she has hitherto borne it better than we could have hoped. (363/7. Susan Darwin died in October 1866.) Remember glacial action of Lebanon when you speak of no glacial action in S. on Himalaya, and in S.E. Australia. P.S.--I have been very glad to see Sir C. Bunbury's letter. (363/8. The letter from Bunbury to Lyell, already quoted on this subject. Bunbury writes: "There is nothing in the least NORTHERN, nothing that is not characteristically Brazilian, in the flora of the Organ Mountains.") If the genera which I name from Gardner (363/9. "Travels in the Interior of Brazil," by G. Gardner: London, 1846.) are not considered by him as usually temperate forms, I am, of course, silenced; but Hooker looked over the MS. chapter some ten years ago and did not score out my remarks on them, and he is generally ready enough to pitch into my ignorance and snub me, as I often deserve. My wonder was how any, ever so few, temperate forms reached the mountains of Brazil; and I supposed they travelled by the rather high land and ranges (name forgotten) which stretch from the Cordillera towards Brazil. Cordillera genera of plants have also, somehow, reached the Silla of Caracas. When I think of the vegetation of New Zealand and west coast of South America, where glaciers now descend to or very near to the sea, I feel it rash to conclude that all tropical forms would be destroyed by a considerably cooler period under the Equator. LETTER 364. TO C. LYELL. Down, Thursday, February 15th [1866]. Many thanks for Hooker's letter; it is a real pleasure to me to read his letters; they are always written with such spirit. I quite agree that Agassiz could never mistake weathered blocks and glacial action; though the mistake has, I know, been made in two or three quarters of the world. I have often fought with Hooker about the physicists putting their veto on the world having been cooler; it seems to me as irrational as if, when geologists first brought forward some evidence of elevation and subsidence, a former Hooker had declared that this could not possibly be admitted until geologists could explain what made the earth rise and fall. It seems that I erred greatly about some of the plants on the Organ Mountains. (364/1. "On the Organ Mountains of Brazil some few temperate European, some Antarctic, and some Andean genera were found by Gardner, which did not exist in the low intervening hot countries" ("Origin," Edition VI., page 336).) But I am very glad to hear about Fuchsia, etc. I cannot make out what Hooker does believe; he seems to admit the former cooler climate, and almost in the same breath to spurn the idea. To retort Hooker's words, "it is inexplicable to me" how he can compare the transport of seeds from the Andes to the Organ Mountains with that from a continent to an island. Not to mention the much greater distance, there are no currents of water from one to the other; and what on earth should make a bird fly that distance without resting many times? I do not at all suppose that nearly all tropical forms were exterminated during the cool period; but in somewhat depopulated areas, into which there could be no migration, probably many closely allied species will have been formed since this period. Hooker's paper in the "Natural History Review" (364/2. Possibly an unsigned article, entitled "New Colonial Floras" (a review of Grisebach's "Flora of the British West Indian Islands" and Thwaites' "Enumeratio Plantarum Zeylaniae").--"Nat. Hist. Review," January 1865, page 46. See Letter 184.) is well worth studying; but I cannot remember that he gives good grounds for his conviction that certain orders of plants could not withstand a rather cooler climate, even if it came on most gradually. We have only just learnt under how cool a temperature several tropical orchids can flourish. I clearly saw Hooker's difficulty about the preservation of tropical forms during the cool period, and tried my best to retain one spot after another as a hothouse for their preservation; but it would not hold good, and it was a mere piece of truckling on my part when I suggested that longitudinal belts of the world were cooled one after the other. I shall very much like to see Agassiz's letter, whenever you receive one. I have written a long letter; but a squabble with or about Hooker always does me a world of good, and we have been at it many a long year. I cannot understand whether he attacks me as a wriggler or a hammerer, but I am very sure that a deal of wriggling has to be done. LETTER 365. TO J.D. HOOKER. Down, July 30th [1866]. Many thanks about the lupin. Your letter has interested me extremely, and reminds me of old times. I suppose, by your writing, you would like to hear my notions. I cannot admit the Atlantis connecting Madeira and Canary Islands without the strongest evidence, and all on that side (365/1. Sir J.D. Hooker lectured on "Insular Floras" at the Nottingham meeting of the British Association on August 27th, 1866. His lecture is given in the "Gardeners' Chronicle," 1867, page 6. No doubt he was at this time preparing his remarks on continental extension, which take the form of a judicial statement, giving the arguments and difficulties on both sides. He sums up against continental extension, which, he says, accounts for everything and explains nothing; "whilst the hypothesis of trans-oceanic migration, though it leaves a multitude of facts unexplained, offers a rational solution of many of the most puzzling phenomena." In his lecture, Sir Joseph wrote that in ascending the mountains in Madeira there is but little replacement of lowland species by those of a higher northern latitude. "Plants become fewer and fewer as we ascend, and their places are not taken by boreal ones, or by but very few."): the depth is so great; there is nothing geologically in the islands favouring the belief; there are no endemic mammals or batrachians. Did not Bunbury show that some Orders of plants were singularly deficient? But I rely chiefly on the large amount of specific distinction in the insects and land-shells of P. Santo and Madeira: surely Canary and Madeira could not have been connected, if Madeira and P. Santo had long been distinct. If you admit Atlantis, I think you are bound to admit or explain the difficulties. With respect to cold temperate plants in Madeira, I, of course, know not enough to form an opinion; but, admitting Atlantis, I can see their rarity is a great difficulty; otherwise, seeing that the latitude is only a little north of the Persian Gulf, and seeing the long sea-transport for seeds, the rarity of northern plants does not seem to me difficult. The immigration may have been from a southerly direction, and it seems that some few African as well as coldish plants are common to the mountains to the south. Believing in occasional transport, I cannot feel so much surprise at there being a good deal in common to Madeira and Canary, these being the nearest points of land to each other. It is quite new and very interesting to me what you say about the endemic plants being in so large a proportion rare species. From the greater size of the workshop (i.e., greater competition and greater number of individuals, etc.) I should expect that continental forms, as they are occasionally introduced, would always tend to beat the insular forms; and, as in every area, there will always be many forms more or less rare tending towards extinction, I should certainly have expected that in islands a large proportion of the rarer forms would have been insular in their origin. The longer the time any form has existed in an island into which continental forms are occasionally introduced, by so much the chances will be in favour of its being peculiar or abnormal in nature, and at the same time scanty in numbers. The duration of its existence will also have formerly given it the best chance, when it was not so rare, of being widely distributed to adjoining archipelagoes. Here is a wriggle: the older a form is, the better the chance will be of its having become developed into a tree! An island from being surrounded by the sea will prevent free immigration and competition, hence a greater number of ancient forms will survive on an island than on the nearest continent whence the island was stocked; and I have always looked at Clethra (365/2. Clethra is an American shrubby genus of Ericaceae, found nowhere nearer to Madeira than North America. Of this plant and of Persea, Sir Charles Lyell ("Principles," 1872, Volume II., page 422) says: "Regarded as relics of a Miocene flora, they are just such forms as we should naturally expect to have come from the adjoining Miocene continent." See also "Origin of Species," Edition VI., page 83, where a similar view is quoted from Heer.) and the other extra-European forms as remnants of the Tertiary flora which formerly inhabited Europe. This preservation of ancient forms in islands appears to me like the preservation of ganoid fishes in our present freshwaters. You speak of no northern plants on mountains south of the Pyrenees: does my memory quite deceive me that Boissier published a long list from the mountains in Southern Spain? I have not seen Wollaston's, "Catalogue," (365/4. Probably the "Catalogue of the Coleopterous Insects of the Canaries in the British Museum," 1864.) but must buy it, if it gives the facts about rare plants which you mention. And now I have given more than enough of my notions, which I well know will be in flat contradiction with all yours. Wollaston, in his "Insecta Maderensia" (365/5. "Insecta Maderensia," London, 1854.), 4to, page 12, and in his "Variation of Species," pages 82-7, gives the case of apterous insects, but I remember I worked out some additional details. I think he gives in these same works the proportion of European insects. LETTER 366. TO J.D. HOOKER. (366/1. Sir Joseph had asked (July 31st, 1866): "Is there an evidence that the south of England and of Ireland were not submerged during the Glacial epoch, when the W. and N. of England were islands in a glacial sea? And supposing they were above water, could the present Atlantic and N.W. of France floras we now find there have been there during the Glacial epoch?--Yet this is what Forbes demands, page 346. At page 347 he sees this objection, and wriggles out of his difficulty by putting the date of the Channel 'towards the close of the Glacial epoch.' What does Austen make the date of the Channel?--ante or post Glacial?" The changes in level and other questions are dealt with in a paper by R.A.C. Austen (afterwards Godwin-Austen), "On the Superficial Accumulations of the Coasts of the English Channel and the Changes they indicate." "Quart. Journ. Geol. Soc." VII., 1851, page 118. Obit. notice by Prof. Bonney in the "Proc. Geol. Soc." XLI., page 37, 1885.) Down, August 3rd [1866]. I will take your letter seriatim. There is good evidence that S.E. England was dry land during the Glacial period. I forget what Austen says, but Mammals prove, I think, that England has been united to the Continent since the Glacial period. I don't see your difficulty about what I say on the breaking of an isthmus: if Panama was broken through would not the fauna of the Pacific flow into the W. Indies, or vice versa, and destroy a multitude of creatures? Of course I'm no judge, but I thought De Candolle had made out his case about small areas of trees. You will find at page 112, 3rd edition "Origin," a too concise allusion to the Madeira flora being a remnant of the Tertiary European flora. I shall feel deeply interested by reading your botanical difficulties against occasional immigration. The facts you give about certain plants, such as the heaths, are certainly very curious. (366/2. In Hooker's lecture he gives St. Dabeoc's Heath and Calluna vulgaris as the most striking of the few boreal plants in the Azores. Darwin seems to have been impressed by the boreal character of the Azores, thus taking the opposite view to that of Sir Joseph. See Letter 370, note.) I thought the Azores flora was more boreal, but what can you mean by saying that the Azores are nearer to Britain and Newfoundland than to Madeira?--on the globe they are nearly twice as far off. (366/3. See Letter 368.) With respect to sea currents, I formerly made enquiries at Madeira, but cannot now give you the results; but I remember that the facts were different from what is generally stated: I think that a ship wrecked on the Canary Islands was thrown up on the coast of Madeira. You speak as if only land-shells differed in Madeira and Porto Santo: does my memory deceive me that there is a host of representative insects? When you exorcise at Nottingham occasional means of transport, be honest, and admit how little is known on the subject. Remember how recently you and others thought that salt water would soon kill seeds. Reflect that there is not a coral islet in the ocean which is not pretty well clothed with plants, and the fewness of the species can hardly with justice be attributed to the arrival of few seeds, for coral islets close to other land support only the same limited vegetation. Remember that no one knew that seeds would remain for many hours in the crops of birds and retain their vitality; that fish eat seeds, and that when the fish are devoured by birds the seeds can germinate, etc. Remember that every year many birds are blown to Madeira and to the Bermudas. Remember that dust is blown 1,000 miles over the Atlantic. Now, bearing all this in mind, would it not be a prodigy if an unstocked island did not in the course of ages receive colonists from coasts whence the currents flow, trees are drifted and birds are driven by gales. The objections to islands being thus stocked are, as far as I understand, that certain species and genera have been more freely introduced, and others less freely than might have been expected. But then the sea kills some sorts of seeds, others are killed by the digestion of birds, and some would be more liable than others to adhere to birds' feet. But we know so very little on these points that it seems to me that we cannot at all tell what forms would probably be introduced and what would not. I do not for a moment pretend that these means of introduction can be proved to have acted; but they seem to me sufficient, with no valid or heavy objections, whilst there are, as it seems to me, the heaviest objections on geological and on geographical distribution grounds (pages 387, 388, "Origin" (366/4. Edition III., or Edition VI., page 323.) to Forbes' enormous continental extensions. But I fear that I shall and have bored you. LETTER 367. J.D. HOOKER TO CHARLES DARWIN. (367/1. In a letter of July 31st, Sir J.D. Hooker wrote, "You must not suppose me to be a champion of continental connection, because I am not agreeable to trans-oceanic migration...either hypothesis appears to me well to cover the facts of oceanic floras, but there are grave objections to both, botanical to yours, geological to Forbes'.") The following interesting letters give some of Sir Joseph's difficulties.) Kew, August 4th, 1866. You mention ("Journal") no land-birds, except introduced, upon St. Helena. Beatson (Introduction xvii) mentions one (367/2. Aegialitis sanctae-helenae, a small plover "very closely allied to a species found in South Africa, but presenting certain differences which entitle it to the rank of a peculiar species" (Wallace, "Island Life," page 294). In the earlier editions of the "Origin" (e.g. Edition III., page 422) Darwin wrote that "Madeira does not possess one peculiar bird." In Edition IV., 1866, page 465, the mistake was put right.) "in considerable numbers," resembles sand-lark--is called "wire bird," has long greenish legs like wires, runs fast, eyes large, bill moderately long, is rather shy, does not possess much powers of flight. What was it? I have written to ask Sclater, also about birds of Madeira and Azores. It is a very curious thing that the Azores do not contain the (non-European) American genus Clethra, that is found in Madeira and Canaries, and that the Azores contain no trace of American element (beyond what is common to Madeira), except a species of Sanicula, a genus with hooked bristles to the small seed-vessels. The European Sanicula roams from Norway to Madeira, Canaries, Cape Verde, Cameroons, Cape of Good Hope, and from Britain to Japan, and also is, I think, in N. America; but does not occur in the Azores, where it is replaced by one that is of a decidedly American type. This tells heavily against the doctrine that joins Atlantis to America, and is much against your trans-oceanic migration--for considering how near the Azores are to America, and in the influence of the Gulf-stream and prevalent winds, it certainly appears marvellous. Not only are the Azores in a current that sweeps the coast of U. States, but they are in the S.W. winds, and in the eye of the S.W. hurricanes! I suppose you will answer that the European forms are prepotent, but this is riding prepotency to death. R.T. Lowe has written me a capital letter on the Madeiran, Canarian, and Cape Verde floras. I misled you if I gave you to understand that Wollaston's Catalogue said anything about rare plants. I am worked and worried to death with this lecture: and curse myself as a soft headed and hearted imbecile to have accepted it. LETTER 368. J.D. HOOKER TO CHARLES DARWIN. Kew, Monday [August 6th, 1866]. Again thanks for your letter. You need not fear my not doing justice to your objections to the continental hypothesis! Referring to page 344 again (368/1. "Origin of Species," Edition III., pages 343-4: "In some cases, however, as by the breaking of an isthmus and the consequent irruption of a multitude of new inhabitants, or by the final subsidence of an island, the extinction may have been comparatively rapid."), it never occurred to me that you alluded to extinction of marine life: an isthmus is a piece of land, and you go on in the same sentence about "an island," which quite threw me out, for the destruction of an isthmus makes an island! I surely did not say Azores nearer to Britain and Newfoundland "than to Madeira," but "than Madeira is to said places." With regard to the Madeiran coleoptera I rely very little on local distribution of insects--they are so local themselves. A butterfly is a great rarity in Kew, even a white, though we are surrounded by market gardens. All insects are most rare with us, even the kinds that abound on the opposite side of Thames. So with shells, we have literally none--not a Helix even, though they abound in the lanes 200 yards off the Gardens. Of the 89 Dezertas insects [only?] 11 are peculiar. Of the 162 Porto Santan 113 are Madeiran and 51 Dezertan. Never mind bothering Murray about the new edition of the "Origin" for me. You will tell me anything bearing on my subject. LETTER 369. J.D. HOOKER TO CHARLES DARWIN. Kew, August 7th, 1866. Dear old Darwin, You must not let me worry you. I am an obstinate pig, but you must not be miserable at my looking at the same thing in a different light from you. I must get to the bottom of this question, and that is all I can do. Some cleverer fellow one day will knock the bottom out of it, and see his way to explain what to a botanist without a theory to support must be very great difficulties. True enough, all may be explained, as you reason it will be--I quite grant this; but meanwhile all is not so explained, and I cannot accept a hypothesis that leaves so many facts unaccounted for. You say the temperate parts of N. America [are] nearly two and a half times as distant from the Azores as Europe is. According to a rough calculation on Col. James' chart I make E. Azores to Portugal 850, West do. to Newfoundland 1500, but I am writing to a friend at Admiralty to have the distance calculated (which looks like cracking nuts with Nasmyth's hammer!) Are European birds blown to America? Are the Azorean erratics an established fact? I want them very badly, though they are not of much consequence, as a slight sinking would hide all evidence of that sort. I do want to sum up impartially, leaving the verdict to jury. I cannot do this without putting all difficulties most clearly. How do you know how you would fare with me if you were a continentalist! Then too we must recollect that I have to meet a host who are all on the continental side--in fact, pretty nearly all the thinkers, Forbes, Hartung, Heer, Unger, Wollaston, Lowe (Wallace, I suppose), and now Andrew Murray. I do not regard all these, and snap my fingers at all but you; in my inmost soul I conscientiously say I incline to your theory, but I cannot accept it as an established truth or unexceptionable hypothesis. The "Wire bird" being a Grallator is a curious fact favourable to you...How I do yearn to go out again to St. Helena. Of course I accept the ornithological evidence as tremendously strong, though why they should get blown westerly, and not change specifically, as insects, shells, and plants have done, is a mystery. LETTER 370. TO J.D. HOOKER. Down, August 8th [1866]. It would be a very great pleasure to me if I could think that my letters were of the least use to you. I must have expressed myself badly for you to suppose that I look at islands being stocked by occasional transport as a well-established hypothesis. We both give up creation, and therefore have to account for the inhabitants of islands either by continental extensions or by occasional transport. Now, all that I maintain is that of these two alternatives, one of which must be admitted, notwithstanding very many difficulties, occasional transport is by far the most probable. I go thus far further--that I maintain, knowing what we do, that it would be inexplicable if unstocked islands were not stocked to a certain extent at least by these occasional means. European birds are occasionally driven to America, but far more rarely than in the reverse direction: they arrive via Greenland (Baird); yet a European lark has been caught in Bermuda. By the way, you might like to hear that European birds regularly migrate via the northern islands to Greenland. About the erratics in the Azores see "Origin," page 393. (370/1. "Origin," Edition VI., page 328. The importance of erratic blocks on the Azores is in showing the probability of ice-borne seeds having stocked the islands, and thus accounting for the number of European species and their unexpectedly northern character. Darwin's delight in the verification of his theory is described in a letter to Sir Joseph of April 26th, 1858, in the "Life and Letters," II., page 112.) Hartung could hardly be mistaken about granite blocks on a volcanic island. I do not think it a mystery that birds have not been modified in Madeira. (370/2. "Origin," Edition VI., page 328. Madeira has only one endemic bird. Darwin accounts for the fact from the island having been stocked with birds which had struggled together and become mutually co-adapted on the neighbouring continents. "Hence, when settled in their new homes, each kind will have been kept by the others in its proper place and habits, and will consequently have been but little liable to modification." Crossing with frequently arriving immigrants will also tend to keep down modification.) Pray look at page 422 of "Origin" [Edition III.]. You would not think it a mystery if you had seen the long lists which I have (somewhere) of the birds annually blown, even in flocks, to Madeira. The crossed stock would be the more vigorous. Remember if you do not come here before Nottingham, if you do not come afterwards I shall think myself diabolically ill-used. LETTER 371. J.D. HOOKER TO CHARLES DARWIN. Kew, August 9th, 1866. If my letters did not gene you it is impossible that you should suppose that yours were of no use to me! I would throw up the whole thing were it not for correspondence with you, which is the only bit of silver in the affair. I do feel it disgusting to have to make a point of a speciality in which I cannot see my way a bit further than I could before I began. To be sure, I have a very much clearer notion of the pros and cons on both sides (though these were rather forgotten facts than rediscoveries). I see the sides of the well further down more distinctly, but the bottom is as obscure as ever. I think I know the "Origin" by heart in relation to the subject, and it was reading it that suggested the queries about Azores boulders and Madeira birds. The former you and I have talked over, and I thought I remembered that you wanted it confirmed. The latter strikes me thus: why should plants and insects have been so extensively changed and birds not at all? I perfectly understand and feel the force of your argument in reference to birds per se, but why do these not apply to insects and plants? Can you not see that this suggests the conclusion that the plants are derived one way and the birds another? I certainly did take it for granted that you supposed the stocking [by] occasional transport to be something even more than a "well-established hypothesis," but disputants seldom stop to measure the strength of their antagonist's opinion. I shall be with you on Saturday week, I hope. I should have come before, but have made so little progress that I could not. I am now at St. Helena, and shall then go to, and finish with, Kerguelen's land. (371/1. After giving the distances of the Azores, etc., from America, Sir Joseph continues:--) But to my mind [it] does not mend the matter--for I do not ask why Azores have even proportionally (to distance) a smaller number of American plants, but why they have none, seeing the winds and currents set that way. The Bermudas are all American in flora, but from what Col. Munro informs me I should say they have nothing but common American weeds and the juniper (cedar). No changed forms, yet they are as far from America as Azores from Europe. I suppose they are modern and out of the pale. ...There is this, to me, astounding difference between certain oceanic islands which were stocked by continental extension and those stocked by immigration (following in both definitions your opinion), that the former [continental] do contain many types of the more distant continent, the latter do not any! Take Madagascar, with its many Asiatic genera unknown in Africa; Ceylon, with many Malayan types not Peninsular; Japan, with many non-Asiatic American types. Baird's fact of Greenland migration I was aware of since I wrote my Arctic paper. I wish I was as satisfied either of continental [extensions] or of transport means as I am of my Greenland hypothesis! Oh, dear me, what a comfort it is to have a belief (sneer away). LETTER 372. J.D. HOOKER TO CHARLES DARWIN. Kew, December 4th, 1866. I have just finished the New Zealand "Manual" (372/1. "Handbook of the New Zealand Flora."), and am thinking about a discussion on the geographical distribution, etc., of the plants. There is scarcely a single indigenous annual plant in the group. I wish that I knew more of the past condition of the islands, and whether they have been rising or sinking. There is much that suggests the idea that the islands were once connected during a warmer epoch, were afterwards separated and much reduced in area to what they now are, and lastly have assumed their present size. The remarkable general uniformity of the flora, even of the arboreous flora, throughout so many degrees of latitude, is a very remarkable feature, as is the representation of a good many of the southern half of certain species of the north, by very closely allied varieties or species; and, lastly, there is the immense preponderance of certain genera whose species all run into one another and vary horribly, and which suggest a rising area. I hear that a whale has been found some miles inland. LETTER 373. J.D. HOOKER TO CHARLES DARWIN. Kew, December 14th, 1866. I do not see how the mountains of New Zealand, S. Australia, and Tasmania could have been peopled, and [with] so large an extent of antarctic (373/1. "Introductory Essay to Flora of New Zealand," page xx. "The plants of the Antarctic islands, which are equally natives of New Zealand, Tasmania, and Australia, are almost invariably found only on the lofty mountains of these countries.") forms common to Fuegia, without some intercommunication. And I have always supposed this was before the immigration of Asiatic plants into Australia, and of which plants the temperate and tropical plants of that country may be considered as altered forms. The presence of so many of these temperate and cold Australian and New Zealand genera on the top of Kini Balu in Borneo (under the equator) is an awful staggerer, and demands a very extended northern distribution of Australian temperate forms. It is a frightful assumption that the plains of Borneo were covered with a temperate cold vegetation that was driven up Kini Balu by the returning cold. Then there is the very distant distribution of a few Australian types northward to the Philippines, China, and Japan: that is a fearful and wonderful fact, though, as these plants are New Zealand too for the most part, the migration northward may have been east of Australia. LETTER 374. TO J.D. HOOKER. December 24th [1866]. ...One word more about the flora derived from supposed Pleistocene antarctic land requiring land intercommunication. This will depend much, as it seems to me, upon how far you finally settle whether Azores, Cape de Verdes, Tristan d'Acunha, Galapagos, Juan Fernandez, etc., etc., etc., have all had land intercommunication. If you do not think this necessary, might not New Zealand, etc., have been stocked during commencing Glacial period by occasional means from antarctic land? As for lowlands of Borneo being tenanted by a moderate number of temperate forms during the Glacial period, so far [is it] from appearing a "frightful assumption" that I am arrived at that pitch of bigotry that I look at it as proved! LETTER 375. J.D. HOOKER TO CHARLES DARWIN. Kew, December 25th, 1866. I was about to write to-day, when your jolly letter came this morning, to tell you that after carefully going over the N.Z. Flora, I find that there are only about thirty reputed indigenous Dicot. annuals, of which almost half, not being found by Banks and Solander, are probably non-indigenous. This is just 1/20th of the Dicots., or, excluding the doubtful, about 1/40th, whereas the British proportion of annuals is 1/4.6 amongst Dicots.!!! Of the naturalised New Zealand plants one-half are annual! I suppose there can be no doubt but that a deciduous-leaved vegetation affords more conditions for vegetable life than an evergreen one, and that it is hence that we find countries characterised by uniform climates to be poor in species, and those to be evergreens. I can now work this point out for New Zealand and Britain. Japan may be an exception: it is an extraordinary evergreen country, and has many species apparently, but it has so much novelty that it may not be so rich in species really as it hence looks, and I do believe it is very poor. It has very few annuals. Then, again, I think that the number of plants with irregular flowers, and especially such as require insect agency, diminishes much with evergreenity. Hence in all humid temperate regions we have, as a rule, few species, many evergreens, few annuals, few Leguminosae and orchids, few lepidoptera and other flying insects, many Coniferae, Amentaceae, Gramineae, Cyperaceae, and other wind-fertilised trees and plants, etc. Orchids and Leguminosae are scarce in islets, because the necessary fertilising insects have not migrated with the plants. Perhaps you have published this. LETTER 376. TO J.D. HOOKER. Down, January 9th [1867]. I like the first part of your paper in the "Gard. Chronicle" (376/1. The lecture on Insular Floras ("Gard. Chron." January 1867).) to an extraordinary degree: you never, in my opinion, wrote anything better. You ask for all, even minute criticisms. In the first column you speak of no alpine plants and no replacement by zones, which will strike every one with astonishment who has read Humboldt and Webb on Zones on Teneriffe. Do you not mean boreal or arctic plants? (376/2. The passage which seems to be referred to does mention the absence of BOREAL plants.) In the third column you speak as if savages (376/3. "Such plants on oceanic islands are, like the savages which in some islands have been so long the sole witnesses of their existence, the last representatives of their several races.") had generally viewed the endemic plants of the Atlantic islands. Now, as you well know, the Canaries alone of all the archipelagoes were inhabited. In the third column have you really materials to speak of confirming the proportion of winged and wingless insects on islands? Your comparison of plants of Madeira with islets of Great Britain is admirable. (376/4. "What should we say, for instance, if a plant so totally unlike anything British as the Monizia edulis...were found on one rocky islet of the Scillies, or another umbelliferous plant, Melanoselinum...on one mountain in Wales; or if the Isle of Wight and Scilly Islands had varieties, species, and genera too, differing from anything in Britain, and found nowhere else in the world!") I must allude to one of your last notes with very curious case of proportion of annuals in New Zealand. (376/5. On this subject see Hildebrand's interesting paper "Die Lebensdauer der Pflanzen" (Engler's "Botanische Jahrbucher," Volume II., 1882, page 51). He shows that annuals are rare in very dry desert-lands, in northern and alpine regions. The following table gives the percentages of annuals, etc., in various situations in Freiburg (Baden):-- Annuals. Biennials. Perennials. Trees and Shrubs. Sandy, dry, and stony places: 21 11 65 3 Dry fields: 6 4 90 Damp fields: 12 2 77 9 Woods and copses: 3 2 65 31 Water: 3 97 Cultivated land: 89 11 Are annuals adapted for short seasons, as in arctic regions, or tropical countries with dry season, or for periodically disturbed and cultivated ground? You speak of evergreen vegetation as leading to few or confined conditions; but is not evergreen vegetation connected with humid and equable climate? Does not a very humid climate almost imply (Tyndall) an equable one? I have never printed a word that I can remember about orchids and papilionaceous plants being few in islands on account of rarity of insects; and I remember you screamed at me when I suggested this a propos of Papilionaceae in New Zealand, and of the statement about clover not seeding there till the hive-bee was introduced, as I stated in my paper in "Gard. Chronicle." (376/6. "In an old number of the "Gardeners' Chronicle" an extract is given from a New Zealand newspaper in which much surprise is expressed that the introduced clover never seeded freely until the hive-bee was introduced." "On the Agency of Bees in the Fertilisation of Papilionaceous Flowers..." ("Gard. Chron." 1858, page 828). See Letter 362, note.) I have been these last few days vexed and annoyed to a foolish degree by hearing that my MS. on Domestic Animals, etc., will make two volumes, both bigger than the "Origin." The volumes will have to be full-sized octavo, so I have written to Murray to suggest details to be printed in small type. But I feel that the size is quite ludicrous in relation to the subject. I am ready to swear at myself and at every fool who writes a book. LETTER 377. TO J.D. HOOKER. Down, January 15th [1867]. Thanks for your jolly letter. I have read your second article (377/1. The lecture on Insular Floras was published in instalments in the "Gardeners' Chronicle," January 5th, 12th, 19th, 26th, 1867.), and like it even more than the first, and more than this I cannot say. By mere chance I stumbled yesterday on a passage in Humboldt that a violet grows on the Peak of Teneriffe in common with the Pyrenees. If Humboldt is right that the Canary Is. which lie nearest to the continent have a much stronger African character than the others, ought you not just to allude to this? I do not know whether you admit, and if so allude to, the view which seems to me probable, that most of the genera confined to the Atlantic islands (I do not say the species) originally existed in, and were derived from, Europe, [and have] become extinct on this continent. I should thus account for the community of peculiar genera in the several Atlantic islands. About the Salvages is capital. (377/2. The Salvages are rocky islets about midway between Madeira and the Canaries; and they have an Atlantic flora, instead of, as might have been expected, one composed of African immigrants. ("Insular Floras," page 5 of separate copy.)) I am glad you speak of LINKING, though this sounds a little too close, instead of being continuous. All about St. Helena is grand. You have no faith, but if I knew any one who lived in St. Helena I would supplicate him to send me home a cask or two of earth from a few inches beneath the surface from the upper part of the island, and from any dried-up pond, and thus, as sure as I'm a wriggler, I should receive a multitude of lost plants. I did suggest to you to work out proportion of plants with irregular flowers on islands; I did this after giving a very short discussion on irregular flowers in my Lythrum paper. (377/3. "Linn. Soc. Journ." VIII., 1865, page 169.) But what on earth has a mere suggestion like this to do with meum and tuum? You have comforted me much about the bigness of my book, which yet turns me sick when I think of it. 
1909	----	DARWIN AND MODERN SCIENCE ESSAYS IN COMMEMORATION OF THE CENTENARY OF THE BIRTH OF CHARLES DARWIN AND OF THE FIFTIETH ANNIVERSARY OF THE PUBLICATION OF "THE ORIGIN OF SPECIES" By A.C. Seward "My success as a man of science, whatever this may have amounted to, has been determined, as far as I can judge, by complex and diversified mental qualities and conditions. Of these, the most important have been--the love of science--unbounded patience in long reflecting over any subject--industry in observing and collecting facts--and a fair share of invention as well as of common sense. With such moderate abilities as I possess, it is truly surprising that I should have influenced to a considerable extent the belief of scientific men on some important points." Autobiography (1881); "The Life and Letters of Charles Darwin", Vol. 1. page 107. PREFACE At the suggestion of the Cambridge Philosophical Society, the Syndics of the University Press decided in March, 1908, to arrange for the publication of a series of Essays in commemoration of the Centenary of the birth of Charles Darwin and of the Fiftieth anniversary of the publication of "The Origin of Species". The preliminary arrangements were made by a committee consisting of the following representatives of the Council of the Philosophical Society and of the Press Syndicate: Dr H.K. Anderson, Prof. Bateson, Mr Francis Darwin, Dr Hobson, Dr Marr, Prof. Sedgwick, Mr David Sharp, Mr Shipley, Prof. Sorley, Prof. Seward. In the course of the preparation of the volume, the original scheme and list of authors have been modified: a few of those invited to contribute essays were, for various reasons, unable to do so, and some alterations have been made in the titles of articles. For the selection of authors and for the choice of subjects, the committee are mainly responsible, but for such share of the work in the preparation of the volume as usually falls to the lot of an editor I accept full responsibility. Authors were asked to address themselves primarily to the educated layman rather than to the expert. It was hoped that the publication of the essays would serve the double purpose of illustrating the far-reaching influence of Darwin's work on the progress of knowledge and the present attitude of original investigators and thinkers towards the views embodied in Darwin's works. In regard to the interpretation of a passage in "The Origin of Species" quoted by Hugo de Vries, it seemed advisable to add an editorial footnote; but, with this exception, I have not felt it necessary to record any opinion on views stated in the essays. In reading the essays in proof I have availed myself freely of the willing assistance of several Cambridge friends, among whom I wish more especially to thank Mr Francis Darwin for the active interest he has taken in the preparation of the volume. Mrs J.A. Thomson kindly undertook the translation of the essays by Prof. Weismann and Prof. Schwalbe; Mrs James Ward was good enough to assist me by translating Prof. Bougle's article on Sociology, and to Mr McCabe I am indebted for the translation of the essay by Prof. Haeckel. For the translation of the botanical articles by Prof. Goebel, Prof. Klebs and Prof. Strasburger, I am responsible; in the revision of the translation of Prof. Strasburger's essay Madame Errera of Brussels rendered valuable help. Mr Wright, the Secretary of the Press Syndicate, and Mr Waller, the Assistant Secretary, have cordially cooperated with me in my editorial work; nor can I omit to thank the readers of the University Press for keeping watchful eyes on my shortcomings in the correction of proofs. The two portraits of Darwin are reproduced by permission of Messrs Maull and Fox and Messrs Elliott and Fry. The photogravure of the study at Down is reproduced from an etching by Mr Axel Haig, lent by Mr Francis Darwin; the coloured plate illustrating Prof. Weismann's essay was originally published by him in his "Vortrage uber Descendenztheorie" which afterwards appeared (1904) in English under the title "The Evolution Theory". Copies of this plate were supplied by Messrs Fischer of Jena. The Syndics of the University Press have agreed, in the event of this volume being a financial success, to hand over the profits to a University fund for the endowment of biological research. It is clearly impossible to express adequately in a single volume of Essays the influence of Darwin's contributions to knowledge on the subsequent progress of scientific inquiry. As Huxley said in 1885: "Whatever be the ultimate verdict of posterity upon this or that opinion which Mr Darwin has propounded; whatever adumbrations or anticipations of his doctrines may be found in the writings of his predecessors; the broad fact remains that, since the publication and by reason of the publication of "The Origin of Species" the fundamental conceptions and the aims of the students of living Nature have been completely changed... But the impulse thus given to scientific thought rapidly spread beyond the ordinarily recognised limits of Biology. Psychology, Ethics, Cosmology were stirred to their foundations, and 'The Origin of Species' proved itself to be the fixed point which the general doctrine needed in order to move the world." In the contributions to this Memorial Volume, some of the authors have more especially concerned themselves with the results achieved by Darwin's own work, while others pass in review the progress of research on lines which, though unknown or but little followed in his day, are the direct outcome of his work. The divergence of views among biologists in regard to the origin of species and as to the most promising directions in which to seek for truth is illustrated by the different opinions of contributors. Whether Darwin's views on the modus operandi of evolutionary forces receive further confirmation in the future, or whether they are materially modified, in no way affects the truth of the statement that, by employing his life "in adding a little to Natural Science," he revolutionised the world of thought. Darwin wrote in 1872 to Alfred Russel Wallace: "How grand is the onward rush of science: it is enough to console us for the many errors which we have committed, and for our efforts being overlaid and forgotten in the mass of new facts and new views which are daily turning up." In the onward rush, it is easy for students convinced of the correctness of their own views and equally convinced of the falsity of those of their fellow-workers to forget the lessons of Darwin's life. In his autobiographical sketch, he tells us, "I have steadily endeavoured to keep my mind free so as to give up any hypothesis, however much beloved...as soon as facts are shown to be opposed to it." Writing to Mr J. Scott, he says, "It is a golden rule, which I try to follow, to put every fact which is opposed to one's preconceived opinion in the strongest light. Absolute accuracy is the hardest merit to attain, and the highest merit. Any deviation is ruin." He acted strictly in accordance with his determination expressed in a letter to Lyell in 1844, "I shall keep out of controversy, and just give my own facts." As was said of another son of Cambridge, Sir George Stokes, "He would no more have thought of disputing about priority, or the authorship of an idea, than of writing a report for a company promoter." Darwin's life affords a striking confirmation of the truth of Hazlitt's aphorism, "Where the pursuit of truth has been the habitual study of any man's life, the love of truth will be his ruling passion." Great as was the intellect of Darwin, his character, as Huxley wrote, was even nobler than his intellect. A.C. SEWARD. Botany School, Cambridge, March 20, 1909. CONTENTS I. INTRODUCTORY LETTER TO THE EDITOR from SIR JOSEPH DALTON HOOKER, O.M. II. DARWIN'S PREDECESSORS: J. ARTHUR THOMSON, Professor of Natural History in the University of Aberdeen. III. THE SELECTION THEORY: AUGUST WEISMANN, Professor of Zoology in the University of Freiburg (Baden). IV. VARIATION: HUGO DE VRIES, Professor of Botany in the University of Amsterdam. V. HEREDITY AND VARIATION IN MODERN LIGHTS: W. BATESON, Professor of Biology in the University of Cambridge. VI. THE MINUTE STRUCTURE OF CELLS IN RELATION TO HEREDITY: EDUARD STRASBURGER, Professor of Botany in the University of Bonn. VII. "THE DESCENT OF MAN": G. SCHWALBE, Professor of Anatomy in the University of Strassburg. VIII. CHARLES DARWIN AS AN ANTHROPOLOGIST: ERNST HAECKEL, Professor of Zoology in the University of Jena. IX. SOME PRIMITIVE THEORIES OF THE ORIGIN OF MAN: J.G. FRAZER, Fellow of Trinity College, Cambridge. X. THE INFLUENCE OF DARWIN ON THE STUDY OF ANIMAL EMBRYOLOGY: A. SEDGWICK, Professor of Zoology and Comparative Anatomy in the University of Cambridge. XI. THE PALAEONTOLOGICAL RECORD. I. ANIMALS: W.B. SCOTT, Professor of Geology in the University of Princeton. XII. THE PALAEONTOLOGICAL RECORD. II. PLANTS: D.H. SCOTT, President of the Linnean Society of London. XIII. THE INFLUENCE OF ENVIRONMENT ON THE FORMS OF PLANTS: GEORG KLEBS, Professor of Botany in the University of Heidelberg. XIV. EXPERIMENTAL STUDY OF THE INFLUENCE OF ENVIRONMENT ON ANIMALS: JACQUES LOEB, Professor of Physiology in the University of California. XV. THE VALUE OF COLOUR IN THE STRUGGLE FOR LIFE: E.B. POULTON, Hope Professor of Zoology in the University of Oxford. XVI. GEOGRAPHICAL DISTRIBUTION OF PLANTS: SIR WILLIAM THISELTON-DYER. XVII. GEOGRAPHICAL DISTRIBUTION OF ANIMALS: HANS GADOW, Strickland Curator and Lecturer on Zoology in the University of Cambridge. XVIII. DARWIN AND GEOLOGY: J.W. JUDD. XIX. DARWIN'S WORK ON THE MOVEMENTS OF PLANTS: FRANCIS DARWIN. XX. THE BIOLOGY OF FLOWERS: K. GOEBEL, Professor of Botany in the University of Munich. XXI. MENTAL FACTORS IN EVOLUTION: C. LLOYD MORGAN, Professor of Psychology at University College, Bristol. XXII. THE INFLUENCE OF THE CONCEPTION OF EVOLUTION ON MODERN PHILOSOPHY: H. HOFFDING, Professor of Philosophy in the University of Copenhagen. XXIII. DARWINISM AND SOCIOLOGY: C. BOUGLE, Professor of Social Philosophy in the University of Toulouse, and Deputy-Professor at the Sorbonne, Paris. XXIV. THE INFLUENCE OF DARWIN UPON RELIGIOUS THOUGHT: REV. P.N. WAGGETT. XXV. THE INFLUENCE OF DARWINISM ON THE STUDY OF RELIGIONS: JANE ELLEN HARRISON, Staff-Lecturer and sometime Fellow of Newnham College, Cambridge. XXVI. EVOLUTION AND THE SCIENCE OF LANGUAGE: P. GILES, Reader in Comparative Philology in the University of Cambridge. XXVII. DARWINISM AND HISTORY: J.B. BURY, Regius Professor of Modern History in the University of Cambridge. XXVIII. THE GENESIS OF DOUBLE STARS: SIR GEORGE DARWIN, Plumian Professor of Astronomy and Experimental Philosophy in the University of Cambridge. XXIX. THE EVOLUTION OF MATTER: W.C.D. WHETHAM, Fellow of Trinity College, Cambridge. INDEX. DATES OF THE PUBLICATION Of CHARLES DARWIN'S BOOKS AND OF THE PRINCIPAL EVENTS IN HIS LIFE 1809: Charles Darwin born at Shrewsbury, February 12. 1817: "At 8 1/2 years old I went to Mr Case's school." (A day-school at Shrewsbury kept by the Rev G. Case, Minister of the Unitarian Chapel.) 1818: "I was at school at Shrewsbury under a great scholar, Dr Butler; I learnt absolutely nothing, except by amusing myself by reading and experimenting in Chemistry." 1825: "As I was doing no good at school, my father wisely took me away at a rather earlier age than usual, and sent me (Oct. 1825) to Edinburgh University with my brother, where I stayed for two years." 1828: Began residence at Christ's College, Cambridge. "I went to Cambridge early in the year 1828, and soon became acquainted with Professor Henslow...Nothing could be more simple, cordial and unpretending than the encouragement which he afforded to all young naturalists." "During the three years which I spent at Cambridge my time was wasted, as far as the academical studies were concerned, as completely as at Edinburgh and at school." "In order to pass the B.A. Examination, it was...necessary to get up Paley's 'Evidences of Christianity,' and his 'Moral Philosophy'... The careful study of these works, without attempting to learn any part by rote, was the only part of the academical course which...was of the least use to me in the education of my mind." 1831: Passed the examination for the B.A. degree in January and kept the following terms. "I gained a good place among the oi polloi or crowd of men who do not go in for honours." "I am very busy,...and see a great deal of Henslow, whom I do not know whether I love or respect most." Dec. 27. "Sailed from England on our circumnavigation," in H.M.S. "Beagle", a barque of 235 tons carrying 6 guns, under Capt. FitzRoy. "There is indeed a tide in the affairs of men." 1836: Oct. 4. "Reached Shrewsbury after absence of 5 years and 2 days." "You cannot imagine how gloriously delightful my first visit was at home; it was worth the banishment." Dec. 13. Went to live at Cambridge (Fitzwilliam Street). "The only evil I found in Cambridge was its being too pleasant." 1837: "On my return home (in the 'Beagle') in the autumn of 1836 I immediately began to prepare my journal for publication, and then saw how many facts indicated the common descent of species... In July (1837) I opened my first note-book for facts in relation to the Origin of Species, about which I had long reflected, and never ceased working for the next twenty years... Had been greatly struck from about the month of previous March on character of South American fossils, and species on Galapagos Archipelago. These facts (especially latter), origin of all my views." "On March 7, 1837 I took lodgings in (36) Great Marlborough Street in London, and remained there for nearly two years, until I was married." 1838: "In October, that is fifteen months after I had begun my systematic enquiry, I happened to read for amusement 'Malthus on Population,' and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here then I had at last got a theory by which to work; but I was so anxious to avoid prejudice, that I determined not for some time to write even the briefest sketch of it." 1839: Married at Maer (Staffordshire) to his first cousin Emma Wedgwood, daughter of Josiah Wedgwood. "I marvel at my good fortune that she, so infinitely my superior in every single moral quality, consented to be my wife. She has been my wise adviser and cheerful comforter throughout life, which without her would have been during a very long period a miserable one from ill-health. She has earned the love of every soul near her" (Autobiography). Dec. 31. "Entered 12 Upper Gower street" (now 110 Gower street, London). "There never was so good a house for me, and I devoutly trust you (his future wife) will approve of it equally. The little garden is worth its weight in gold." Published "Journal and Researches", being Vol. III. of the "Narrative of the Surveying Voyage of H.M.S. 'Adventure' and 'Beagle'"... Publication of the "Zoology of the Voyage of H.M.S. 'Beagle'", Part II., "Mammalia", by G.R. Waterhouse, with a "Notice of their habits and ranges", by Charles Darwin. 1840: Contributed Geological Introduction to Part I. ("Fossil Mammalia") of the "Zoology of the Voyage of H.M.S. 'Beagle'" by Richard Owen. 1842: "In June 1842 I first allowed myself the satisfaction of writing a very brief abstract of my (species) theory in pencil in 35 pages; and this was enlarged during the summer of 1844 into one of 230 pages, which I had fairly copied out and still (1876) possess." (The first draft of "The Origin of Species", edited by Mr Francis Darwin, will be published this year (1909) by the Syndics of the Cambridge University Press.) Sept. 14. Settled at the village of Down in Kent. "I think I was never in a more perfectly quiet country." Publication of "The Structure and Distribution of Coral Reefs"; being Part I. of the "Geology of the Voyage of the Beagle". 1844: Publication of "Geological Observations on the Volcanic Islands visited during the Voyage of H.M.S. 'Beagle'"; being Part II. of the "Geology of the Voyage of the 'Beagle'". "I think much more highly of my book on Volcanic Islands since Mr Judd, by far the best judge on the subject in England, has, as I hear, learnt much from it." (Autobiography, 1876.) 1845: Publication of the "Journal of Researches" as a separate book. 1846: Publication of "Geological Observations on South America"; being Part III. of the "Geology of the Voyage of the 'Beagle'". 1851: Publication of a "Monograph of the Fossil Lepadidae" and of a "Monograph of the sub-class Cirripedia". "I fear the study of the Cirripedia will ever remain 'wholly unapplied,' and yet I feel that such study is better than castle-building." 1854: Publication of Monographs of the Balanidae and Verrucidae. "I worked steadily on this subject for...eight years, and ultimately published two thick volumes, describing all the known living species, and two thin quartos on the extinct species... My work was of considerable use to me, when I had to discuss in the "Origin of Species" the principles of a natural classification. Nevertheless, I doubt whether the work was worth the consumption of so much time." "From September 1854 I devoted my whole time to arranging my huge pile of notes, to observing, and to experimenting in relation to the transmutation of species." 1856: "Early in 1856 Lyell advised me to write out my views pretty fully, and I began at once to do so on a scale three or four times as extensive as that which was afterwards followed in my 'Origin of Species'." 1858: Joint paper by Charles Darwin and Alfred Russel Wallace "On the Tendency of Species to form Varieties; and on the perpetuation of Varieties and Species by Natural Means of Selection," communicated to the Linnean Society by Sir Charles Lyell and Sir Joseph Hooker. "I was at first very unwilling to consent (to the communication of his MS. to the Society) as I thought Mr Wallace might consider my doing so unjustifiable, for I did not then know how generous and noble was his disposition." "July 20 to Aug. 12 at Sandown (Isle of Wight) began abstract of Species book." 1859: Nov. 24. Publication of "The Origin of Species" (1250 copies). "Oh, good heavens, the relief to my head and body to banish the whole subject from my mind!... But, alas, how frequent, how almost universal it is in an author to persuade himself of the truth of his own dogmas. My only hope is that I certainly see many difficulties of gigantic stature." 1860: Publication of the second edition of the "Origin" (3000 copies). Publication of a "Naturalist's Voyage". 1861: Publication of the third edition of the "Origin" (2000 copies). "I am going to write a little book... on Orchids, and to-day I hate them worse than everything." 1862: Publication of the book "On the various contrivances by which Orchids are fertilised by Insects". 1865: Read paper before the Linnean Society "On the Movements and Habits of Climbing plants". (Published as a book in 1875.) 1866: Publication of the fourth edition of the "Origin" (1250 copies). 1868: "I have sent the MS. of my big book, and horridly, disgustingly big it will be, to the printers." Publication of the "Variation of Animals and Plants under Domestication". "About my book, I will give you (Sir Joseph Hooker) a bit of advice. Skip the whole of Vol. I, except the last chapter, (and that need only be skimmed), and skip largely in the 2nd volume; and then you will say it is a very good book." "Towards the end of the work I give my well-abused hypothesis of Pangenesis. An unverified hypothesis is of little or no value; but if anyone should hereafter be led to make observations by which some such hypothesis could be established, I shall have done good service, as an astonishing number of isolated facts can be thus connected together and rendered intelligible." 1869: Publication of the fifth edition of the "Origin". 1871: Publication of "The Descent of Man". "Although in the 'Origin of Species' the derivation of any particular species is never discussed, yet I thought it best, in order that no honourable man should accuse me of concealing my views, to add that by the work 'light would be thrown on the origin of man and his history'." 1872: Publication of the sixth edition of the "Origin". Publication of "The Expression of the Emotions in Man and Animals". 1874: Publication of the second edition of "The Descent of Man". "The new edition of the "Descent" has turned out an awful job. It took me ten days merely to glance over letters and reviews with criticisms and new facts. It is a devil of a job." Publication of the second edition of "The Structure and Distribution of Coral Reefs". 1875: Publication of "Insectivorous Plants". "I begin to think that every one who publishes a book is a fool." Publication of the second edition of "Variation in Animals and Plants". Publication of "The Movements and Habits of Climbing Plants" as a separate book. 1876: Wrote Autobiographical Sketch ("Life and Letters", Vol. I., Chap II.). Publication of "The Effects of Cross and Self fertilisation". "I now (1881) believe, however,...that I ought to have insisted more strongly than I did on the many adaptations for self-fertilisation." Publication of the second edition of "Observations on Volcanic Islands". 1877: Publication of "The Different Forms of Flowers on Plants of the same species". "I do not suppose that I shall publish any more books... I cannot endure being idle, but heaven knows whether I am capable of any more good work." Publication of the second edition of the Orchid book. 1878: Publication of the second edition of "The Effects of Cross and Self fertilisation". 1879: Publication of an English translation of Ernst Krause's "Erasmus Darwin", with a notice by Charles Darwin. "I am EXTREMELY glad that you approve of the little 'Life' of our Grandfather, for I have been repenting that I ever undertook it, as the work was quite beyond my tether." (To Mr Francis Galton, Nov. 14, 1879.) 1880: Publication of "The Power of Movement in Plants". "It has always pleased me to exalt plants in the scale of organised beings." Publication of the second edition of "The Different Forms of Flowers". 1881: Wrote a continuation of the Autobiography. Publication of "The Formation of Vegetable Mould, through the Action of Worms". "It is the completion of a short paper read before the Geological Society more than forty years ago, and has revived old geological thoughts... As far as I can judge it will be a curious little book." 1882: Charles Darwin died at Down, April 19, and was buried in Westminster Abbey, April 26, in the north aisle of the Nave a few feet from the grave of Sir Isaac Newton. "As for myself, I believe that I have acted rightly in steadily following and devoting my life to Science. I feel no remorse from having committed any great sin, but have often and often regretted that I have not done more direct good to my fellow creatures." The quotations in the above Epitome are taken from the Autobiography and published Letters:-- "The Life and Letters of Charles Darwin", including an Autobiographical Chapter. Edited by his son, Francis Darwin, 3 Vols., London, 1887. "Charles Darwin": His life told in an Autobiographical Chapter, and in a selected series of his published Letters. Edited by his son, Francis Darwin, London, 1902. "More Letters of Charles Darwin". A record of his work in a series of hitherto unpublished Letters. Edited by Francis Darwin and A.C. Seward, 2 Vols., London, 1903. I. INTRODUCTORY LETTER From Sir Joseph Dalton Hooker, O.M., G.C.S.I., C.B., M.D., D.C.L., LL.D., F.R.S., ETC. The Camp, near Sunningdale, January 15, 1909. Dear Professor Seward, The publication of a Series of Essays in Commemoration of the century of the birth of Charles Darwin and of the fiftieth anniversary of the publication of "The Origin of Species" is assuredly welcome and is a subject of congratulation to all students of Science. These Essays on the progress of Science and Philosophy as affected by Darwin's labours have been written by men known for their ability to discuss the problems which he so successfully worked to solve. They cannot but prove to be of enduring value, whether for the information of the general reader or as guides to investigators occupied with problems similar to those which engaged the attention of Darwin. The essayists have been fortunate in having for reference the five published volumes of Charles Darwin's Life and Correspondence. For there is set forth in his own words the inception in his mind of the problems, geological, zoological and botanical, hypothetical and theoretical, which he set himself to solve and the steps by which he proceeded to investigate them with the view of correlating the phenomena of life with the evolution of living things. In his letters he expressed himself in language so lucid and so little burthened with technical terms that they may be regarded as models for those who were asked to address themselves primarily to the educated reader rather than to the expert. I may add that by no one can the perusal of the Essays be more vividly appreciated than by the writer of these lines. It was my privilege for forty years to possess the intimate friendship of Charles Darwin and to be his companion during many of his working hours in Study, Laboratory, and Garden. I was the recipient of letters from him, relating mainly to the progress of his researches, the copies of which (the originals are now in the possession of his family) cover upwards of a thousand pages of foolscap, each page containing, on an average, three hundred words. That the editorship of these Essays has been entrusted to a Cambridge Professor of Botany must be gratifying to all concerned in their production and in their perusal, recalling as it does the fact that Charles Darwin's instructor in scientific methods was his lifelong friend the late Rev. J.S. Henslow at that time Professor of Botany in the University. It was owing to his recommendation that his pupil was appointed Naturalist to H.M.S. "Beagle", a service which Darwin himself regarded as marking the dawn of his scientific career. Very sincerely yours, J.D. HOOKER. II. DARWIN'S PREDECESSORS. By J. Arthur Thomson. Professor of Natural History in the University of Aberdeen. In seeking to discover Darwin's relation to his predecessors it is useful to distinguish the various services which he rendered to the theory of organic evolution. (I) As everyone knows, the general idea of the Doctrine of Descent is that the plants and animals of the present-day are the lineal descendants of ancestors on the whole somewhat simpler, that these again are descended from yet simpler forms, and so on backwards towards the literal "Protozoa" and "Protophyta" about which we unfortunately know nothing. Now no one supposes that Darwin originated this idea, which in rudiment at least is as old as Aristotle. What Darwin did was to make it current intellectual coin. He gave it a form that commended itself to the scientific and public intelligence of the day, and he won wide-spread conviction by showing with consummate skill that it was an effective formula to work with, a key which no lock refused. In a scholarly, critical, and pre-eminently fair-minded way, admitting difficulties and removing them, foreseeing objections and forestalling them, he showed that the doctrine of descent supplied a modal interpretation of how our present-day fauna and flora have come to be. (II) In the second place, Darwin applied the evolution-idea to particular problems, such as the descent of man, and showed what a powerful organon it is, introducing order into masses of uncorrelated facts, interpreting enigmas both of structure and function, both bodily and mental, and, best of all, stimulating and guiding further investigation. But here again it cannot be claimed that Darwin was original. The problem of the descent or ascent of man, and other particular cases of evolution, had attracted not a few naturalists before Darwin's day, though no one (except Herbert Spencer in the psychological domain (1855)) had come near him in precision and thoroughness of inquiry. (III) In the third place, Darwin contributed largely to a knowledge of the factors in the evolution-process, especially by his analysis of what occurs in the case of domestic animals and cultivated plants, and by his elaboration of the theory of Natural Selection, which Alfred Russel Wallace independently stated at the same time, and of which there had been a few previous suggestions of a more or less vague description. It was here that Darwin's originality was greatest, for he revealed to naturalists the many different forms--often very subtle--which natural selection takes, and with the insight of a disciplined scientific imagination he realised what a mighty engine of progress it has been and is. (IV) As an epoch-marking contribution, not only to Aetiology but to Natural History in the widest sense, we rank the picture which Darwin gave to the world of the web of life, that is to say, of the inter-relations and linkages in Nature. For the Biology of the individual--if that be not a contradiction in terms--no idea is more fundamental than that of the correlation of organs, but Darwin's most characteristic contribution was not less fundamental,--it was the idea of the correlation of organisms. This, again, was not novel; we find it in the works of naturalist like Christian Conrad Sprengel, Gilbert White, and Alexander von Humboldt, but the realisation of its full import was distinctively Darwinian. AS REGARDS THE GENERAL IDEA OF ORGANIC EVOLUTION. While it is true, as Prof. H.F. Osborn puts it, that "'Before and after Darwin' will always be the ante et post urbem conditam of biological history," it is also true that the general idea of organic evolution is very ancient. In his admirable sketch "From the Greeks to Darwin" ("Columbia University Biological Series", Vol. I. New York and London, 1894. We must acknowledge our great indebtness to this fine piece of work.), Prof. Osborn has shown that several of the ancient philosophers looked upon Nature as a gradual development and as still in process of change. In the suggestions of Empedocles, to take the best instance, there were "four sparks of truth,--first, that the development of life was a gradual process; second, that plants were evolved before animals; third, that imperfect forms were gradually replaced (not succeeded) by perfect forms; fourth, that the natural cause of the production of perfect forms was the extinction of the imperfect." (Op. cit. page 41.) But the fundamental idea of one stage giving origin to another was absent. As the blue Aegean teemed with treasures of beauty and threw many upon its shores, so did Nature produce like a fertile artist what had to be rejected as well as what was able to survive, but the idea of one species emerging out of another was not yet conceived. Aristotle's views of Nature (See G.J. Romanes, "Aristotle as a Naturalist", "Contemporary Review", Vol. LIX. page 275, 1891; G. Pouchet "La Biologie Aristotelique", Paris, 1885; E. Zeller, "A History of Greek Philosophy", London, 1881, and "Ueber die griechischen Vorganger Darwin's", "Abhandl. Berlin Akad." 1878, pages 111-124.) seem to have been more definitely evolutionist than those of his predecessors, in this sense, at least, that he recognised not only an ascending scale, but a genetic series from polyp to man and an age-long movement towards perfection. "It is due to the resistance of matter to form that Nature can only rise by degrees from lower to higher types." "Nature produces those things which, being continually moved by a certain principle contained in themselves, arrive at a certain end." To discern the outcrop of evolution-doctrine in the long interval between Aristotle and Bacon seems to be very difficult, and some of the instances that have been cited strike one as forced. Epicurus and Lucretius, often called poets of evolution, both pictured animals as arising directly out of the earth, very much as Milton's lion long afterwards pawed its way out. Even when we come to Bruno who wrote that "to the sound of the harp of the Universal Apollo (the World Spirit), the lower organisms are called by stages to higher, and the lower stages are connected by intermediate forms with the higher," there is great room, as Prof. Osborn points out (op. cit. page 81.), for difference of opinion as to how far he was an evolutionist in our sense of the term. The awakening of natural science in the sixteenth century brought the possibility of a concrete evolution theory nearer, and in the early seventeenth century we find evidences of a new spirit--in the embryology of Harvey and the classifications of Ray. Besides sober naturalists there were speculative dreamers in the sixteenth and seventeenth centuries who had at least got beyond static formulae, but, as Professor Osborn points out (op. cit. page 87.), "it is a very striking fact, that the basis of our modern methods of studying the Evolution problem was established not by the early naturalists nor by the speculative writers, but by the Philosophers." He refers to Bacon, Descartes, Leibnitz, Hume, Kant, Lessing, Herder, and Schelling. "They alone were upon the main track of modern thought. It is evident that they were groping in the dark for a working theory of the Evolution of life, and it is remarkable that they clearly perceived from the outset that the point to which observation should be directed was not the past but the present mutability of species, and further, that this mutability was simply the variation of individuals on an extended scale." Bacon seems to have been one of the first to think definitely about the mutability of species, and he was far ahead of his age in his suggestion of what we now call a Station of Experimental Evolution. Leibnitz discusses in so many words how the species of animals may be changed and how intermediate species may once have linked those that now seem discontinuous. "All natural orders of beings present but a single chain"... "All advances by degrees in Nature, and nothing by leaps." Similar evolutionist statements are to be found in the works of the other "philosophers," to whom Prof. Osborn refers, who were, indeed, more scientific than the naturalists of their day. It must be borne in mind that the general idea of organic evolution--that the present is the child of the past--is in great part just the idea of human history projected upon the natural world, differentiated by the qualification that the continuous "Becoming" has been wrought out by forces inherent in the organisms themselves and in their environment. A reference to Kant (See Brock, "Die Stellung Kant's zur Deszendenztheorie," "Biol. Centralbl." VIII. 1889, pages 641-648. Fritz Schultze, "Kant und Darwin", Jena, 1875.) should come in historical order after Buffon, with whose writings he was acquainted, but he seems, along with Herder and Schelling, to be best regarded as the culmination of the evolutionist philosophers--of those at least who interested themselves in scientific problems. In a famous passage he speaks of "the agreement of so many kinds of animals in a certain common plan of structure"... an "analogy of forms" which "strengthens the supposition that they have an actual blood-relationship, due to derivation from a common parent." He speaks of "the great Family of creatures, for as a Family we must conceive it, if the above-mentioned continuous and connected relationship has a real foundation." Prof. Osborn alludes to the scientific caution which led Kant, biology being what it was, to refuse to entertain the hope "that a Newton may one day arise even to make the production of a blade of grass comprehensible, according to natural laws ordained by no intention." As Prof. Haeckel finely observes, Darwin rose up as Kant's Newton. (Mr Alfred Russel Wallace writes: "We claim for Darwin that he is the Newton of natural history, and that, just so surely as that the discovery and demonstration by Newton of the law of gravitation established order in place of chaos and laid a sure foundation for all future study of the starry heavens, so surely has Darwin, by his discovery of the law of natural selection and his demonstration of the great principle of the preservation of useful variations in the struggle for life, not only thrown a flood of light on the process of development of the whole organic world, but also established a firm foundation for all future study of nature." ("Darwinism", London, 1889, page 9). See also Prof. Karl Pearson's "Grammar of Science" (2nd edition), London, 1900, page 32. See Osborn, op. cit. Page 100.)) The scientific renaissance brought a wealth of fresh impressions and some freedom from the tyranny of tradition, and the twofold stimulus stirred the speculative activity of a great variety of men from old Claude Duret of Moulins, of whose weird transformism (1609) Dr Henry de Varigny ("Experimental Evolution". London, 1892. Chap. 1. page 14.) gives us a glimpse, to Lorenz Oken (1799-1851) whose writings are such mixtures of sense and nonsense that some regard him as a far-seeing prophet and others as a fatuous follower of intellectual will-o'-the-wisps. Similarly, for De Maillet, Maupertuis, Diderot, Bonnet, and others, we must agree with Professor Osborn that they were not actually in the main Evolution movement. Some have been included in the roll of honour on very slender evidence, Robinet for instance, whose evolutionism seems to us extremely dubious. (See J. Arthur Thomson, "The Science of Life". London, 1899. Chap. XVI. "Evolution of Evolution Theory".) The first naturalist to give a broad and concrete expression to the evolutionist doctrine of descent was Buffon (1707-1788), but it is interesting to recall the fact that his contemporary Linnaeus (1707-1778), protagonist of the counter-doctrine of the fixity of species (See Carus Sterne (Ernest Krause), "Die allgemeine Weltanschauung in ihrer historischen Entwickelung". Stuttgart, 1889. Chapter entitled "Bestandigkeit oder Veranderlichkeit der Naturwesen".), went the length of admitting (in 1762) that new species might arise by intercrossing. Buffon's position among the pioneers of the evolution-doctrine is weakened by his habit of vacillating between his own conclusions and the orthodoxy of the Sorbonne, but there is no doubt that he had a firm grasp of the general idea of "l'enchainement des etres." Erasmus Darwin (1731-1802), probably influenced by Buffon, was another firm evolutionist, and the outline of his argument in the "Zoonomia" ("Zoonomia, or the Laws of Organic Life", 2 vols. London, 1794; Osborn op. cit. page 145.) might serve in part at least to-day. "When we revolve in our minds the metamorphoses of animals, as from the tadpole to the frog; secondly, the changes produced by artificial cultivation, as in the breeds of horses, dogs, and sheep; thirdly, the changes produced by conditions of climate and of season, as in the sheep of warm climates being covered with hair instead of wool, and the hares and partridges of northern climates becoming white in winter: when, further, we observe the changes of structure produced by habit, as seen especially in men of different occupations; or the changes produced by artificial mutilation and prenatal influences, as in the crossing of species and production of monsters; fourth, when we observe the essential unity of plan in all warm-blooded animals,--we are led to conclude that they have been alike produced from a similar living filament"... "From thus meditating upon the minute portion of time in which many of the above changes have been produced, would it be too bold to imagine, in the great length of time since the earth began to exist, perhaps millions of years before the commencement of the history of mankind, that all warm-blooded animals have arisen from one living filament?"... "This idea of the gradual generation of all things seems to have been as familiar to the ancient philosophers as to the modern ones, and to have given rise to the beautiful hieroglyphic figure of the proton oon, or first great egg, produced by night, that is, whose origin is involved in obscurity, and animated by Eros, that is, by Divine Love; from whence proceeded all things which exist." Lamarck (1744-1829) seems to have become an evolutionist independently of Erasmus Darwin's influence, though the parallelism between them is striking. He probably owed something to Buffon, but he developed his theory along a different line. Whatever view be held in regard to that theory there is no doubt that Lamarck was a thorough-going evolutionist. Professor Haeckel speaks of the "Philosophie Zoologique" as "the first connected and thoroughly logical exposition of the theory of descent." (See Alpheus S. Packard, "Lamarck, the Founder of Evolution, His Life and Work, with Translations of his writings on Organic Evolution". London, 1901.) Besides the three old masters, as we may call them, Buffon, Erasmus Darwin, and Lamarck, there were other quite convinced pre-Darwinian evolutionists. The historian of the theory of descent must take account of Treviranus whose "Biology or Philosophy of Animate Nature" is full of evolutionary suggestions; of Etienne Geoffroy St Hilaire, who in 1830, before the French Academy of Sciences, fought with Cuvier, the fellow-worker of his youth, an intellectual duel on the question of descent; of Goethe, one of the founders of morphology and the greatest poet of Evolution--who, in his eighty-first year, heard the tidings of Geoffroy St Hilaire's defeat with an interest which transcended the political anxieties of the time; and of many others who had gained with more or less confidence and clearness a new outlook on Nature. It will be remembered that Darwin refers to thirty-four more or less evolutionist authors in his Historical Sketch, and the list might be added to. Especially when we come near to 1858 do the numbers increase, and one of the most remarkable, as also most independent champions of the evolution-idea before that date was Herbert Spencer, who not only marshalled the arguments in a very forcible way in 1852, but applied the formula in detail in his "Principles of Psychology" in 1855. (See Edward Clodd, "Pioneers of Evolution", London, page 161, 1897.) It is right and proper that we should shake ourselves free from all creationist appreciations of Darwin, and that we should recognise the services of pre-Darwinian evolutionists who helped to make the time ripe, yet one cannot help feeling that the citation of them is apt to suggest two fallacies. It may suggest that Darwin simply entered into the labours of his predecessors, whereas, as a matter of fact, he knew very little about them till after he had been for years at work. To write, as Samuel Butler did, "Buffon planted, Erasmus Darwin and Lamarck watered, but it was Mr Darwin who said 'That fruit is ripe,' and shook it into his lap"... seems to us a quite misleading version of the facts of the case. The second fallacy which the historical citation is a little apt to suggest is that the filiation of ideas is a simple problem. On the contrary, the history of an idea, like the pedigree of an organism, is often very intricate, and the evolution of the evolution-idea is bound up with the whole progress of the world. Thus in order to interpret Darwin's clear formulation of the idea of organic evolution and his convincing presentation of it, we have to do more than go back to his immediate predecessors, such as Buffon, Erasmus Darwin, and Lamarck; we have to inquire into the acceptance of evolutionary conceptions in regard to other orders of facts, such as the earth and the solar system (See Chapter IX. "The Genetic View of Nature" in J.T. Merz's "History of European Thought in the Nineteenth Century", Vol. 2, Edinburgh and London, 1903.); we have to realise how the growing success of scientific interpretation along other lines gave confidence to those who refused to admit that there was any domain from which science could be excluded as a trespasser; we have to take account of the development of philosophical thought, and even of theological and religious movements; we should also, if we are wise enough, consider social changes. In short, we must abandon the idea that we can understand the history of any science as such, without reference to contemporary evolution in other departments of activity. While there were many evolutionists before Darwin, few of them were expert naturalists and few were known outside a small circle; what was of much more importance was that the genetic view of nature was insinuating itself in regard to other than biological orders of facts, here a little and there a little, and that the scientific spirit had ripened since the days when Cuvier laughed Lamarck out of court. How was it that Darwin succeeded where others had failed? Because, in the first place, he had clear visions--"pensees de la jeunesse, executees par l'age mur"--which a University curriculum had not made impossible, which the "Beagle" voyage made vivid, which an unrivalled British doggedness made real--visions of the web of life, of the fountain of change within the organism, of the struggle for existence and its winnowing, and of the spreading genealogical tree. Because, in the second place, he put so much grit into the verification of his visions, putting them to the proof in an argument which is of its kind--direct demonstration being out of the question--quite unequalled. Because, in the third place, he broke down the opposition which the most scientific had felt to the seductive modal formula of evolution by bringing forward a more plausible theory of the process than had been previously suggested. Nor can one forget, since questions of this magnitude are human and not merely academic, that he wrote so that all men could understand. AS REGARDS THE FACTORS OF EVOLUTION. It is admitted by all who are acquainted with the history of biology that the general idea of organic evolution as expressed in the Doctrine of Descent was quite familiar to Darwin's grandfather, and to others before and after him, as we have briefly indicated. It must also be admitted that some of these pioneers of evolutionism did more than apply the evolution-idea as a modal formula of becoming, they began to inquire into the factors in the process. Thus there were pre-Darwinian theories of evolution, and to these we must now briefly refer. (See Prof. W.A. Locy's "Biology and its Makers". New York, 1908. Part II. "The Doctrine of Organic Evolution".) In all biological thinking we have to work with the categories Organism--Function--Environment, and theories of evolution may be classified in relation to these. To some it has always seemed that the fundamental fact is the living organism,--a creative agent, a striving will, a changeful Proteus, selecting its environment, adjusting itself to it, self-differentiating and self-adaptive. The necessity of recognising the importance of the organism is admitted by all Darwinians who start with inborn variations, but it is open to question whether the whole truth of what we might call the Goethian position is exhausted in the postulate of inherent variability. To others it has always seemed that the emphasis should be laid on Function,--on use and disuse, on doing and not doing. Practice makes perfect; c'est a force de forger qu'on devient forgeron. This is one of the fundamental ideas of Lamarckism; to some extent it met with Darwin's approval; and it finds many supporters to-day. One of the ablest of these--Mr Francis Darwin--has recently given strong reasons for combining a modernised Lamarckism with what we usually regard as sound Darwinism. (Presidential Address to the British Association meeting at Dublin in 1908.) To others it has always seemed that the emphasis should be laid on the Environment, which wakes the organism to action, prompts it to change, makes dints upon it, moulds it, prunes it, and finally, perhaps, kills it. It is again impossible to doubt that there is truth in this view, for even if environmentally induced "modifications" be not transmissible, environmentally induced "variations" are; and even if the direct influence of the environment be less important than many enthusiastic supporters of this view--may we call them Buffonians--think, there remains the indirect influence which Darwinians in part rely on,--the eliminative process. Even if the extreme view be held that the only form of discriminate elimination that counts is inter-organismal competition, this might be included under the rubric of the animate environment. In many passages Buffon (See in particular Samuel Butler, "Evolution Old and New", London, 1879; J.L. de Lanessan, "Buffon et Darwin", "Revue Scientifique", XLIII. pages 385-391, 425-432, 1889.) definitely suggested that environmental influences--especially of climate and food--were directly productive of changes in organisms, but he did not discuss the question of the transmissibility of the modifications so induced, and it is difficult to gather from his inconsistent writings what extent of transformation he really believed in. Prof. Osborn says of Buffon: "The struggle for existence, the elimination of the least-perfected species, the contest between the fecundity of certain species and their constant destruction, are all clearly expressed in various passages." He quotes two of these (op. cit. page 136.): "Le cours ordinaire de la nature vivante, est en general toujours constant, toujours le meme; son mouvement, toujours regulier, roule sur deux points inebranlables: l'un, la fecondite sans bornes donnee a toutes les especes; l'autre, les obstacles sans nombre qui reduisent cette fecondite a une mesure determinee et ne laissent en tout temps qu'a peu pres la meme quantite d'individus de chaque espece"... "Les especes les moins parfaites, les plus delicates, les plus pesantes, les moins agissantes, les moins armees, etc., ont deja disparu ou disparaitront." Erasmus Darwin (See Ernst Krause and Charles Darwin, "Erasmus Darwin", London, 1879.) had a firm grip of the "idea of the gradual formation and improvement of the Animal world," and he had his theory of the process. No sentence is more characteristic than this: "All animals undergo transformations which are in part produced by their own exertions, in response to pleasures and pains, and many of these acquired forms or propensities are transmitted to their posterity." This is Lamarckism before Lamarck, as his grandson pointed out. His central idea is that wants stimulate efforts and that these result in improvements, which subsequent generations make better still. He realised something of the struggle for existence and even pointed out that this advantageously checks the rapid multiplication. "As Dr Krause points out, Darwin just misses the connection between this struggle and the Survival of the Fittest." (Osborn op. cit. page 142.) Lamarck (1744-1829) (See E. Perrier "La Philosophie Zoologique avant Darwin", Paris, 1884; A. de Quatrefages, "Darwin et ses Precurseurs Francais", Paris, 1870; Packard op. cit.; also Claus, "Lamarck als Begrunder der Descendenzlehre", Wien, 1888; Haeckel, "Natural History of Creation", English translation London, 1879; Lang "Zur Charakteristik der Forschungswege von Lamarck und Darwin", Jena, 1889.) seems to have thought out his theory of evolution without any knowledge of Erasmus Darwin's which it closely resembled. The central idea of his theory was the cumulative inheritance of functional modifications. "Changes in environment bring about changes in the habits of animals. Changes in their wants necessarily bring about parallel changes in their habits. If new wants become constant or very lasting, they form new habits, the new habits involve the use of new parts, or a different use of old parts, which results finally in the production of new organs and the modification of old ones." He differed from Buffon in not attaching importance, as far as animals are concerned, to the direct influence of the environment, "for environment can effect no direct change whatever upon the organisation of animals," but in regard to plants he agreed with Buffon that external conditions directly moulded them. Treviranus (1776-1837) (See Huxley's article "Evolution in Biology", "Encyclopaedia Britannica" (9th edit.), 1878, pages 744-751, and Sully's article, "Evolution in Philosophy", ibid. pages 751-772.), whom Huxley ranked beside Lamarck, was on the whole Buffonian, attaching chief importance to the influence of a changeful environment both in modifying and in eliminating, but he was also Goethian, for instance in his idea that species like individuals pass through periods of growth, full bloom, and decline. "Thus, it is not only the great catastrophes of Nature which have caused extinction, but the completion of cycles of existence, out of which new cycles have begun." A characteristic sentence is quoted by Prof. Osborn: "In every living being there exists a capability of an endless variety of form-assumption; each possesses the power to adapt its organisation to the changes of the outer world, and it is this power, put into action by the change of the universe, that has raised the simple zoophytes of the primitive world to continually higher stages of organisation, and has introduced a countless variety of species into animate Nature." Goethe (1749-1832) (See Haeckel, "Die Naturanschauung von Darwin, Goethe und Lamarck", Jena, 1882.), who knew Buffon's work but not Lamarck's, is peculiarly interesting as one of the first to use the evolution-idea as a guiding hypothesis, e.g. in the interpretation of vestigial structures in man, and to realise that organisms express an attempt to make a compromise between specific inertia and individual change. He gave the finest expression that science has yet known--if it has known it--of the kernel-idea of what is called "bathmism," the idea of an "inherent growth-force"--and at the same time he held that "the way of life powerfully reacts upon all form" and that the orderly growth of form "yields to change from externally acting causes." Besides Buffon, Erasmus Darwin, Lamarck, Treviranus, and Goethe, there were other "pioneers of evolution," whose views have been often discussed and appraised. Etienne Geoffroy Saint-Hilaire (1772-1844), whose work Goethe so much admired, was on the whole Buffonian, emphasising the direct action of the changeful milieu. "Species vary with their environment, and existing species have descended by modification from earlier and somewhat simpler species." He had a glimpse of the selection idea, and believed in mutations or sudden leaps--induced in the embryonic condition by external influences. The complete history of evolution-theories will include many instances of guesses at truth which were afterwards substantiated, thus the geographer von Buch (1773-1853) detected the importance of the Isolation factor on which Wagner, Romanes, Gulick and others have laid great stress, but we must content ourselves with recalling one other pioneer, the author of the "Vestiges of Creation" (1844), a work which passed through ten editions in nine years and certainly helped to harrow the soil for Darwin's sowing. As Darwin said, "it did excellent service in this country in calling attention to the subject, in removing prejudice, and in thus preparing the ground for the reception of analogous views." ("Origin of Species" (6th edition), page xvii.) Its author, Robert Chambers (1802-1871) was in part a Buffonian--maintaining that environment moulded organisms adaptively, and in part a Goethian--believing in an inherent progressive impulse which lifted organisms from one grade of organisation to another. AS REGARDS NATURAL SELECTION. The only thinker to whom Darwin was directly indebted, so far as the theory of Natural Selection is concerned, was Malthus, and we may once more quote the well-known passage in the Autobiography: "In October, 1838, that is, fifteen months after I had begun my systematic enquiry, I happened to read for amusement 'Malthus on Population', and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species." ("The Life and Letters of Charles Darwin", Vol. 1. page 83. London, 1887.) Although Malthus gives no adumbration of the idea of Natural Selection in his exposition of the eliminative processes which go on in mankind, the suggestive value of his essay is undeniable, as is strikingly borne out by the fact that it gave to Alfred Russel Wallace also "the long-sought clue to the effective agent in the evolution of organic species." (A.R. Wallace, "My Life, A Record of Events and Opinions", London, 1905, Vol. 1. page 232.) One day in Ternate when he was resting between fits of fever, something brought to his recollection the work of Malthus which he had read twelve years before. "I thought of his clear exposition of 'the positive checks to increase'--disease, accidents, war, and famine--which keep down the population of savage races to so much lower an average than that of more civilized peoples. It then occurred to me that these causes or their equivalents are continually acting in the case of animals also; and as animals usually breed much more rapidly than does mankind, the destruction every year from these causes must be enormous in order to keep down the numbers of each species, since they evidently do not increase regularly from year to year, as otherwise the world would long ago have been densely crowded with those that breed most quickly. Vaguely thinking over the enormous and constant destruction which this implied, it occurred to me to ask the question, Why do some die and some live? And the answer was clearly, that on the whole the best fitted live. From the effects of disease the most healthy escaped; from enemies the strongest, the swiftest, or the most cunning; from famine the best hunters or those with the best digestion; and so on. Then it suddenly flashed upon me that this self-acting process would necessarily IMPROVE THE RACE, because in every generation the inferior would inevitably be killed off and the superior would remain--that is, THE FITTEST WOULD SURVIVE." (Ibid. Vol. 1. page 361.) We need not apologise for this long quotation, it is a tribute to Darwin's magnanimous colleague, the Nestor of the evolutionist camp,--and it probably indicates the line of thought which Darwin himself followed. It is interesting also to recall the fact that in 1852, when Herbert Spencer wrote his famous "Leader" article on "The Development Hypothesis" in which he argued powerfully for the thesis that the whole animate world is the result of an age-long process of natural transformation, he wrote for "The Westminster Review" another important essay, "A Theory of Population deduced from the General Law of Animal Fertility", towards the close of which he came within an ace of recognising that the struggle for existence was a factor in organic evolution. At a time when pressure of population was practically interesting men's minds, Darwin, Wallace, and Spencer were being independently led from a social problem to a biological theory. There could be no better illustration, as Prof. Patrick Geddes has pointed out, of the Comtian thesis that science is a "social phenomenon." Therefore, as far more important than any further ferreting out of vague hints of Natural Selection in books which Darwin never read, we would indicate by a quotation the view that the central idea in Darwinism is correlated with contemporary social evolution. "The substitution of Darwin for Paley as the chief interpreter of the order of nature is currently regarded as the displacement of an anthropomorphic view by a purely scientific one: a little reflection, however, will show that what has actually happened has been merely the replacement of the anthropomorphism of the eighteenth century by that of the nineteenth. For the place vacated by Paley's theological and metaphysical explanation has simply been occupied by that suggested to Darwin and Wallace by Malthus in terms of the prevalent severity of industrial competition, and those phenomena of the struggle for existence which the light of contemporary economic theory has enabled us to discern, have thus come to be temporarily exalted into a complete explanation of organic progress." (P. Geddes, article "Biology", "Chambers's Encyclopaedia".) It goes without saying that the idea suggested by Malthus was developed by Darwin into a biological theory which was then painstakingly verified by being used as an interpretative formula, and that the validity of a theory so established is not affected by what suggested it, but the practical question which this line of thought raises in the mind is this: if Biology did thus borrow with such splendid results from social theory, why should we not more deliberately repeat the experiment? Darwin was characteristically frank and generous in admitting that the principle of Natural Selection had been independently recognised by Dr W.C. Wells in 1813 and by Mr Patrick Matthew in 1831, but he had no knowledge of these anticipations when he published the first edition of "The Origin of Species". Wells, whose "Essay on Dew" is still remembered, read in 1813 before the Royal Society a short paper entitled "An account of a White Female, part of whose skin resembles that of a Negro" (published in 1818). In this communication, as Darwin said, "he observes, firstly, that all animals tend to vary in some degree, and, secondly, that agriculturists improve their domesticated animals by selection; and then, he adds, but what is done in this latter case 'by art, seems to be done with equal efficacy, though more slowly, by nature, in the formation of varieties of mankind, fitted for the country which they inhabit.'" ("Origin of Species" (6th edition) page xv.) Thus Wells had the clear idea of survival dependent upon a favourable variation, but he makes no more use of the idea and applies it only to man. There is not in the paper the least hint that the author ever thought of generalising the remarkable sentence quoted above. Of Mr Patrick Matthew, who buried his treasure in an appendix to a work on "Naval Timber and Arboriculture", Darwin said that "he clearly saw the full force of the principle of natural selection." In 1860 Darwin wrote--very characteristically--about this to Lyell: "Mr Patrick Matthew publishes a long extract from his work on "Naval Timber and Arboriculture", published in 1831, in which he briefly but completely anticipates the theory of Natural Selection. I have ordered the book, as some passages are rather obscure, but it is certainly, I think, a complete but not developed anticipation. Erasmus always said that surely this would be shown to be the case some day. Anyhow, one may be excused in not having discovered the fact in a work on Naval Timber." ("Life and Letters" II. page 301.) De Quatrefages and De Varigny have maintained that the botanist Naudin stated the theory of evolution by natural selection in 1852. He explains very clearly the process of artificial selection, and says that in the garden we are following Nature's method. "We do not think that Nature has made her species in a different fashion from that in which we proceed ourselves in order to make our variations." But, as Darwin said, "he does not show how selection acts under nature." Similarly it must be noted in regard to several pre-Darwinian pictures of the struggle for existence (such as Herder's, who wrote in 1790 "All is in struggle... each one for himself" and so on), that a recognition of this is only the first step in Darwinism. Profs. E. Perrier and H.F. Osborn have called attention to a remarkable anticipation of the selection-idea which is to be found in the speculations of Etienne Geoffroy St Hilaire (1825-1828) on the evolution of modern Crocodilians from the ancient Teleosaurs. Changing environment induced changes in the respiratory system and far-reaching consequences followed. The atmosphere, acting upon the pulmonary cells, brings about "modifications which are favourable or destructive ('funestes'); these are inherited, and they influence all the rest of the organisation of the animal because if these modifications lead to injurious effects, the animals which exhibit them perish and are replaced by others of a somewhat different form, a form changed so as to be adapted to (a la convenance) the new environment." Prof. E.B. Poulton ("Science Progress", New Series, Vol. I. 1897. "A Remarkable Anticipation of Modern Views on Evolution". See also Chap. VI. in "Essays on Evolution", Oxford, 1908.) has shown that the anthropologist James Cowles Prichard (1786-1848) must be included, even in spite of himself, among the precursors of Darwin. In some passages of the second edition of his "Researches into the Physical History of Mankind" (1826), he certainly talks evolution and anticipates Prof. Weismann in denying the transmission of acquired characters. He is, however, sadly self-contradictory and his evolutionism weakens in subsequent editions--the only ones that Darwin saw. Prof. Poulton finds in Prichard's work a recognition of the operation of Natural Selection. "After enquiring how it is that 'these varieties are developed and preserved in connection with particular climates and differences of local situation,' he gives the following very significant answer: 'One cause which tends to maintain this relation is obvious. Individuals and families, and even whole colonies, perish and disappear in climates for which they are, by peculiarity of constitution, not adapted. Of this fact proofs have been already mentioned.'" Mr Francis Darwin and Prof. A.C. Seward discuss Prichard's "anticipations" in "More Letters of Charles Darwin", Vol. I. page 43, and come to the conclusion that the evolutionary passages are entirely neutralised by others of an opposite trend. There is the same difficulty with Buffon. Hints of the idea of Natural Selection have been detected elsewhere. James Watt (See Prof. Patrick Geddes's article "Variation and Selection", "Encyclopaedia Britannica (9th edition) 1888.), for instance, has been reported as one of the anticipators (1851). But we need not prolong the inquiry further, since Darwin did not know of any anticipations until after he had published the immortal work of 1859, and since none of those who got hold of the idea made any use of it. What Darwin did was to follow the clue which Malthus gave him, to realise, first by genius and afterwards by patience, how the complex and subtle struggle for existence works out a natural selection of those organisms which vary in the direction of fitter adaptation to the conditions of their life. So much success attended his application of the Selection-formula that for a time he regarded Natural Selection as almost the sole factor in evolution, variations being pre-supposed; gradually, however, he came to recognise that there was some validity in the factors which had been emphasized by Lamarck and by Buffon, and in his well-known summing up in the sixth edition of the "Origin" he says of the transformation of species: "This has been effected chiefly through the natural selection of numerous successive, slight, favourable variations; aided in an important manner by the inherited effects of the use and disuse of parts; and in an unimportant manner, that is, in relation to adaptive structures, whether past or present, by the direct action of external conditions, and by variations which seem to us in our ignorance to arise spontaneously." To sum up: the idea of organic evolution, older than Aristotle, slowly developed from the stage of suggestion to the stage of verification, and the first convincing verification was Darwin's; from being an a priori anticipation it has become an interpretation of nature, and Darwin is still the chief interpreter; from being a modal interpretation it has advanced to the rank of a causal theory, the most convincing part of which men will never cease to call Darwinism. III. THE SELECTION THEORY, By August Weismann. Professor of Zoology in the University of Freiburg (Baden). I. THE IDEA OF SELECTION. Many and diverse were the discoveries made by Charles Darwin in the course of a long and strenuous life, but none of them has had so far-reaching an influence on the science and thought of his time as the theory of selection. I do not believe that the theory of evolution would have made its way so easily and so quickly after Darwin took up the cudgels in favour of it, if he had not been able to support it by a principle which was capable of solving, in a simple manner, the greatest riddle that living nature presents to us,--I mean the purposiveness of every living form relative to the conditions of its life and its marvellously exact adaptation to these. Everyone knows that Darwin was not alone in discovering the principle of selection, and that the same idea occurred simultaneously and independently to Alfred Russel Wallace. At the memorable meeting of the Linnean Society on 1st July, 1858, two papers were read (communicated by Lyell and Hooker) both setting forth the same idea of selection. One was written by Charles Darwin in Kent, the other by Alfred Wallace in Ternate, in the Malay Archipelago. It was a splendid proof of the magnanimity of these two investigators, that they thus, in all friendliness and without envy, united in laying their ideas before a scientific tribunal: their names will always shine side by side as two of the brightest stars in the scientific sky. But it is with Charles Darwin that I am here chiefly concerned, since this paper is intended to aid in the commemoration of the hundredth anniversary of his birth. The idea of selection set forth by the two naturalists was at the time absolutely new, but it was also so simple that Huxley could say of it later, "How extremely stupid not to have thought of that." As Darwin was led to the general doctrine of descent, not through the labours of his predecessors in the early years of the century, but by his own observations, so it was in regard to the principle of selection. He was struck by the innumerable cases of adaptation, as, for instance, that of the woodpeckers and tree-frogs to climbing, or the hooks and feather-like appendages of seeds, which aid in the distribution of plants, and he said to himself that an explanation of adaptations was the first thing to be sought for in attempting to formulate a theory of evolution. But since adaptations point to CHANGES which have been undergone by the ancestral forms of existing species, it is necessary, first of all, to inquire how far species in general are VARIABLE. Thus Darwin's attention was directed in the first place to the phenomenon of variability, and the use man has made of this, from very early times, in the breeding of his domesticated animals and cultivated plants. He inquired carefully how breeders set to work, when they wished to modify the structure and appearance of a species to their own ends, and it was soon clear to him that SELECTION FOR BREEDING PURPOSES played the chief part. But how was it possible that such processes should occur in free nature? Who is here the breeder, making the selection, choosing out one individual to bring forth offspring and rejecting others? That was the problem that for a long time remained a riddle to him. Darwin himself relates how illumination suddenly came to him. He had been reading, for his own pleasure, Malthus' book on Population, and, as he had long known from numerous observations, that every species gives rise to many more descendants than ever attain to maturity, and that, therefore, the greater number of the descendants of a species perish without reproducing, the idea came to him that the decision as to which member of a species was to perish, and which was to attain to maturity and reproduction might not be a matter of chance, but might be determined by the constitution of the individuals themselves, according as they were more or less fitted for survival. With this idea the foundation of the theory of selection was laid. In ARTIFICIAL SELECTION the breeder chooses out for pairing only such individuals as possess the character desired by him in a somewhat higher degree than the rest of the race. Some of the descendants inherit this character, often in a still higher degree, and if this method be pursued throughout several generations, the race is transformed in respect of that particular character. NATURAL SELECTION depends on the same three factors as ARTIFICIAL SELECTION: on VARIABILITY, INHERITANCE, and SELECTION FOR BREEDING, but this last is here carried out not by a breeder but by what Darwin called the "struggle for existence." This last factor is one of the special features of the Darwinian conception of nature. That there are carnivorous animals which take heavy toll in every generation of the progeny of the animals on which they prey, and that there are herbivores which decimate the plants in every generation had long been known, but it is only since Darwin's time that sufficient attention has been paid to the facts that, in addition to this regular destruction, there exists between the members of a species a keen competition for space and food, which limits multiplication, and that numerous individuals of each species perish because of unfavourable climatic conditions. The "struggle for existence," which Darwin regarded as taking the place of the human breeder in free nature, is not a direct struggle between carnivores and their prey, but is the assumed competition for survival between individuals OF THE SAME species, of which, on an average, only those survive to reproduce which have the greatest power of resistance, while the others, less favourably constituted, perish early. This struggle is so keen, that, within a limited area, where the conditions of life have long remained unchanged, of every species, whatever be the degree of fertility, only two, ON AN AVERAGE, of the descendants of each pair survive; the others succumb either to enemies, or to disadvantages of climate, or to accident. A high degree of fertility is thus not an indication of the special success of a species, but of the numerous dangers that have attended its evolution. Of the six young brought forth by a pair of elephants in the course of their lives only two survive in a given area; similarly, of the millions of eggs which two thread-worms leave behind them only two survive. It is thus possible to estimate the dangers which threaten a species by its ratio of elimination, or, since this cannot be done directly, by its fertility. Although a great number of the descendants of each generation fall victims to accident, among those that remain it is still the greater or lesser fitness of the organism that determines the "selection for breeding purposes," and it would be incomprehensible if, in this competition, it were not ultimately, that is, on an average, the best equipped which survive, in the sense of living long enough to reproduce. Thus the principle of natural selection is THE SELECTION OF THE BEST FOR REPRODUCTION, whether the "best" refers to the whole constitution, to one or more parts of the organism, or to one or more stages of development. Every organ, every part, every character of an animal, fertility and intelligence included, must be improved in this manner, and be gradually brought up in the course of generations to its highest attainable state of perfection. And not only may improvement of parts be brought about in this way, but new parts and organs may arise, since, through the slow and minute steps of individual or "fluctuating" variations, a part may be added here or dropped out there, and thus something new is produced. The principle of selection solved the riddle as to how what was purposive could conceivably be brought about without the intervention of a directing power, the riddle which animate nature presents to our intelligence at every turn, and in face of which the mind of a Kant could find no way out, for he regarded a solution of it as not to be hoped for. For, even if we were to assume an evolutionary force that is continually transforming the most primitive and the simplest forms of life into ever higher forms, and the homogeneity of primitive times into the infinite variety of the present, we should still be unable to infer from this alone how each of the numberless forms adapted to particular conditions of life should have appeared PRECISELY AT THE RIGHT MOMENT IN THE HISTORY OF THE EARTH to which their adaptations were appropriate, and precisely at the proper place in which all the conditions of life to which they were adapted occurred: the humming-birds at the same time as the flowers; the trichina at the same time as the pig; the bark-coloured moth at the same time as the oak, and the wasp-like moth at the same time as the wasp which protects it. Without processes of selection we should be obliged to assume a "pre-established harmony" after the famous Leibnitzian model, by means of which the clock of the evolution of organisms is so regulated as to strike in exact synchronism with that of the history of the earth! All forms of life are strictly adapted to the conditions of their life, and can persist under these conditions alone. There must therefore be an intrinsic connection between the conditions and the structural adaptations of the organism, and, SINCE THE CONDITIONS OF LIFE CANNOT BE DETERMINED BY THE ANIMAL ITSELF, THE ADAPTATIONS MUST BE CALLED FORTH BY THE CONDITIONS. The selection theory teaches us how this is conceivable, since it enables us to understand that there is a continual production of what is non-purposive as well as of what is purposive, but the purposive alone survives, while the non-purposive perishes in the very act of arising. This is the old wisdom taught long ago by Empedocles. II. THE LAMARCKIAN PRINCIPLE. Lamarck, as is well known, formulated a definite theory of evolution at the beginning of the nineteenth century, exactly fifty years before the Darwin-Wallace principle of selection was given to the world. This brilliant investigator also endeavoured to support his theory by demonstrating forces which might have brought about the transformations of the organic world in the course of the ages. In addition to other factors, he laid special emphasis on the increased or diminished use of the parts of the body, assuming that the strengthening or weakening which takes place from this cause during the individual life, could be handed on to the offspring, and thus intensified and raised to the rank of a specific character. Darwin also regarded this LAMARCKIAN PRINCIPLE, as it is now generally called, as a factor in evolution, but he was not fully convinced of the transmissibility of acquired characters. As I have here to deal only with the theory of selection, I need not discuss the Lamarckian hypothesis, but I must express my opinion that there is room for much doubt as to the cooperation of this principle in evolution. Not only is it difficult to imagine how the transmission of functional modifications could take place, but, up to the present time, notwithstanding the endeavours of many excellent investigators, not a single actual proof of such inheritance has been brought forward. Semon's experiments on plants are, according to the botanist Pfeffer, not to be relied on, and even the recent, beautiful experiments made by Dr Kammerer on salamanders, cannot, as I hope to show elsewhere, be regarded as proof, if only because they do not deal at all with functional modifications, that is, with modifications brought about by use, and it is to these ALONE that the Lamarckian principle refers. III. OBJECTIONS TO THE THEORY OF SELECTION. (a) Saltatory evolution. The Darwinian doctrine of evolution depends essentially on THE CUMULATIVE AUGMENTATION of minute variations in the direction of utility. But can such minute variations, which are undoubtedly continually appearing among the individuals of the same species, possess any selection-value; can they determine which individuals are to survive, and which are to succumb; can they be increased by natural selection till they attain to the highest development of a purposive variation? To many this seems so improbable that they have urged a theory of evolution by leaps from species to species. Kolliker, in 1872, compared the evolution of species with the processes which we can observe in the individual life in cases of alternation of generations. But a polyp only gives rise to a medusa because it has itself arisen from one, and there can be no question of a medusa ever having arisen suddenly and de novo from a polyp-bud, if only because both forms are adapted in their structure as a whole, and in every detail to the conditions of their life. A sudden origin, in a natural way, of numerous adaptations is inconceivable. Even the degeneration of a medusoid from a free-swimming animal to a mere brood-sac (gonophore) is not sudden and saltatory, but occurs by imperceptible modifications throughout hundreds of years, as we can learn from the numerous stages of the process of degeneration persisting at the same time in different species. If, then, the degeneration to a simple brood-sac takes place only by very slow transitions, each stage of which may last for centuries, how could the much more complex ASCENDING evolution possibly have taken place by sudden leaps? I regard this argument as capable of further extension, for wherever in nature we come upon degeneration, it is taking place by minute steps and with a slowness that makes it not directly perceptible, and I believe that this in itself justifies us in concluding that THE SAME MUST BE TRUE OF ASCENDING evolution. But in the latter case the goal can seldom be distinctly recognised while in cases of degeneration the starting-point of the process can often be inferred, because several nearly related species may represent different stages. In recent years Bateson in particular has championed the idea of saltatory, or so-called discontinuous evolution, and has collected a number of cases in which more or less marked variations have suddenly appeared. These are taken for the most part from among domesticated animals which have been bred and crossed for a long time, and it is hardly to be wondered at that their much mixed and much influenced germ-plasm should, under certain conditions, give rise to remarkable phenomena, often indeed producing forms which are strongly suggestive of monstrosities, and which would undoubtedly not survive in free nature, unprotected by man. I should regard such cases as due to an intensified germinal selection--though this is to anticipate a little--and from this point of view it cannot be denied that they have a special interest. But they seem to me to have no significance as far as the transformation of species is concerned, if only because of the extreme rarity of their occurrence. There are, however, many variations which have appeared in a sudden and saltatory manner, and some of these Darwin pointed out and discussed in detail: the copper beech, the weeping trees, the oak with "fern-like leaves," certain garden-flowers, etc. But none of them have persisted in free nature, or evolved into permanent types. On the other hand, wherever enduring types have arisen, we find traces of a gradual origin by successive stages, even if, at first sight, their origin may appear to have been sudden. This is the case with SEASONAL DIMORPHISM, the first known cases of which exhibited marked differences between the two generations, the winter and the summer brood. Take for instance the much discussed and studied form Vanessa (Araschnia) levana-prorsa. Here the differences between the two forms are so great and so apparently disconnected, that one might almost believe it to be a sudden mutation, were it not that old transition-stages can be called forth by particular temperatures, and we know other butterflies, as for instance our Garden Whites, in which the differences between the two generations are not nearly so marked; indeed, they are so little apparent that they are scarcely likely to be noticed except by experts. Thus here again there are small initial steps, some of which, indeed, must be regarded as adaptations, such as the green-sprinkled or lightly tinted under-surface which gives them a deceptive resemblance to parsley or to Cardamine leaves. Even if saltatory variations do occur, we cannot assume that these HAVE EVER LED TO FORMS WHICH ARE CAPABLE OF SURVIVAL UNDER THE CONDITIONS OF WILD LIFE. Experience has shown that in plants which have suddenly varied the power of persistence is diminished. Korschinksky attributes to them weaknesses of organisation in general; "they bloom late, ripen few of their seeds, and show great sensitiveness to cold." These are not the characters which make for success in the struggle for existence. We must briefly refer here to the views--much discussed in the last decade--of H. de Vries, who believes that the roots of transformation must be sought for in SALTATORY VARIATIONS ARISING FROM INTERNAL CAUSES, and distinguishes such MUTATIONS, as he has called them, from ordinary individual variations, in that they breed true, that is, with strict inbreeding they are handed on pure to the next generation. I have elsewhere endeavoured to point out the weaknesses of this theory ("Vortrage uber Descendenztheorie", Jena, 1904, II. 269. English Translation London, 1904, II. page 317.), and I am the less inclined to return to it here that it now appears (See Poulton, "Essays on Evolution", Oxford, 1908, pages xix-xxii.) that the far-reaching conclusions drawn by de Vries from his observations on the Evening Primrose, Oenothera lamarckiana, rest upon a very insecure foundation. The plant from which de Vries saw numerous "species"--his "mutations"--arise was not, as he assumed, a WILD SPECIES that had been introduced to Europe from America, but was probably a hybrid form which was first discovered in the Jardin des Plantes in Paris, and which does not appear to exist anywhere in America as a wild species. This gives a severe shock to the "Mutation theory," for the other ACTUALLY WILD species with which de Vries experimented showed no "mutations" but yielded only negative results. Thus we come to the conclusion that Darwin ("Origin of Species" (6th edition), pages 176 et seq.) was right in regarding transformations as taking place by minute steps, which, if useful, are augmented in the course of innumerable generations, because their possessors more frequently survive in the struggle for existence. (b) SELECTION-VALUE OF THE INITIAL STEPS. Is it possible that the significant deviations which we know as "individual variations" can form the beginning of a process of selection? Can they decide which is to perish and which to survive? To use a phrase of Romanes, can they have SELECTION-VALUE? Darwin himself answered this question, and brought together many excellent examples to show that differences, apparently insignificant because very small, might be of decisive importance for the life of the possessor. But it is by no means enough to bring forward cases of this kind, for the question is not merely whether finished adaptations have selection-value, but whether the first beginnings of these, and whether the small, I might almost say minimal increments, which have led up from these beginnings to the perfect adaptation, have also had selection-value. To this question even one who, like myself, has been for many years a convinced adherent of the theory of selection, can only reply: WE MUST ASSUME SO, BUT WE CANNOT PROVE IT IN ANY CASE. It is not upon demonstrative evidence that we rely when we champion the doctrine of selection as a scientific truth; we base our argument on quite other grounds. Undoubtedly there are many apparently insignificant features, which can nevertheless be shown to be adaptations--for instance, the thickness of the basin-shaped shell of the limpets that live among the breakers on the shore. There can be no doubt that the thickness of these shells, combined with their flat form, protects the animals from the force of the waves breaking upon them,--but how have they become so thick? What proportion of thickness was sufficient to decide that of two variants of a limpet one should survive, the other be eliminated? We can say nothing more than that we infer from the present state of the shell, that it must have varied in regard to differences in shell-thickness, and that these differences must have had selection-value,--no proof therefore, but an assumption which we must show to be convincing. For a long time the marvellously complex RADIATE and LATTICE-WORK skeletons of Radiolarians were regarded as a mere outflow of "Nature's infinite wealth of form," as an instance of a purely morphological character with no biological significance. But recent investigations have shown that these, too, have an adaptive significance (Hacker). The same thing has been shown by Schutt in regard to the lowly unicellular plants, the Peridineae, which abound alike on the surface of the ocean and in its depths. It has been shown that the long skeletal processes which grow out from these organisms have significance not merely as a supporting skeleton, but also as an extension of the superficial area, which increases the contact with the water-particles, and prevents the floating organisms from sinking. It has been established that the processes are considerably shorter in the colder layers of the ocean, and that they may be twelve times as long (Chun, "Reise der Valdivia", Leipzig, 1904.) in the warmer layers, thus corresponding to the greater or smaller amount of friction which takes place in the denser and less dense layers of the water. The Peridineae of the warmer ocean layers have thus become long-rayed, those of the colder layers short-rayed, not through the direct effect of friction on the protoplasm, but through processes of selection, which favoured the longer rays in warm water, since they kept the organism afloat, while those with short rays sank and were eliminated. If we put the question as to selection-value in this case, and ask how great the variations in the length of processes must be in order to possess selection-value; what can we answer except that these variations must have been minimal, and yet sufficient to prevent too rapid sinking and consequent elimination? Yet this very case would give the ideal opportunity for a mathematical calculation of the minimal selection-value, although of course it is not feasible from lack of data to carry out the actual calculation. But even in organisms of more than microscopic size there must frequently be minute, even microscopic differences which set going the process of selection, and regulate its progress to the highest possible perfection. Many tropical trees possess thick, leathery leaves, as a protection against the force of the tropical rain drops. The DIRECT influence of the rain cannot be the cause of this power of resistance, for the leaves, while they were still thin, would simply have been torn to pieces. Their toughness must therefore be referred to selection, which would favour the trees with slightly thicker leaves, though we cannot calculate with any exactness how great the first stages of increase in thickness must have been. Our hypothesis receives further support from the fact that, in many such trees, the leaves are drawn out into a beak-like prolongation (Stahl and Haberlandt) which facilitates the rapid falling off of the rain water, and also from the fact that the leaves, while they are still young, hang limply down in bunches which offer the least possible resistance to the rain. Thus there are here three adaptations which can only be interpreted as due to selection. The initial stages of these adaptations must undoubtedly have had selection-value. But even in regard to this case we are reasoning in a circle, not giving "proofs," and no one who does not wish to believe in the selection-value of the initial stages can be forced to do so. Among the many pieces of presumptive evidence a particularly weighty one seems to me to be THE SMALLNESS OF THE STEPS OF PROGRESS which we can observe in certain cases, as for instance in leaf-imitation among butterflies, and in mimicry generally. The resemblance to a leaf, for instance of a particular Kallima, seems to us so close as to be deceptive, and yet we find in another individual, or it may be in many others, a spot added which increases the resemblance, and which could not have become fixed unless the increased deceptiveness so produced had frequently led to the overlooking of its much persecuted possessor. But if we take the selection-value of the initial stages for granted, we are confronted with the further question which I myself formulated many years ago: How does it happen THAT THE NECESSARY BEGINNINGS OF A USEFUL VARIATION ARE ALWAYS PRESENT? How could insects which live upon or among green leaves become all green, while those that live on bark become brown? How have the desert animals become yellow and the Arctic animals white? Why were the necessary variations always present? How could the green locust lay brown eggs, or the privet caterpillar develop white and lilac-coloured lines on its green skin? It is of no use answering to this that the question is wrongly formulated (Plate, "Selektionsprinzip u. Probleme der Artbildung" (3rd edition), Leipzig, 1908.) and that it is the converse that is true; that the process of selection takes place in accordance with the variations that present themselves. This proposition is undeniably true, but so also is another, which apparently negatives it: the variation required has in the majority of cases actually presented itself. Selection cannot solve this contradiction; it does not call forth the useful variation, but simply works upon it. The ultimate reason why one and the same insect should occur in green and in brown, as often happens in caterpillars and locusts, lies in the fact that variations towards brown presented themselves, and so also did variations towards green: THE KERNEL OF THE RIDDLE LIES IN THE VARYING, and for the present we can only say, that small variations in different directions present themselves in every species. Otherwise so many different kinds of variations could not have arisen. I have endeavoured to explain this remarkable fact by means of the intimate processes that must take place within the germ-plasm, and I shall return to the problem when dealing with "germinal selection." We have, however, to make still greater demands on variation, for it is not enough that the necessary variation should occur in isolated individuals, because in that case there would be small prospect of its being preserved, notwithstanding its utility. Darwin at first believed, that even single variations might lead to transformation of the species, but later he became convinced that this was impossible, at least without the cooperation of other factors, such as isolation and sexual selection. In the case of the GREEN CATERPILLARS WITH BRIGHT LONGITUDINAL STRIPES, numerous individuals exhibiting this useful variation must have been produced to start with. In all higher, that is, multicellular organisms, the germ-substance is the source of all transmissible variations, and this germ-plasm is not a simple substance but is made up of many primary constituents. The question can therefore be more precisely stated thus: How does it come about that in so many cases the useful variations present themselves in numbers just where they are required, the white oblique lines in the leaf-caterpillar on the under surface of the body, the accompanying coloured stripes just above them? And, further, how has it come about that in grass caterpillars, not oblique but longitudinal stripes, which are more effective for concealment among grass and plants, have been evolved? And finally, how is it that the same Hawk-moth caterpillars, which to-day show oblique stripes, possessed longitudinal stripes in Tertiary times? We can read this fact from the history of their development, and I have before attempted to show the biological significance of this change of colour. ("Studien zur Descendenz-Theorie" II., "Die Enstehung der Zeichnung bei den Schmetterlings-raupen," Leipzig, 1876.) For the present I need only draw the conclusion that one and the same caterpillar may exhibit the initial stages of both, and that it depends on the manner in which these marking elements are INTENSIFIED and COMBINED by natural selection whether whitish longitudinal or oblique stripes should result. In this case then the "useful variations" were actually "always there," and we see that in the same group of Lepidoptera, e.g. species of Sphingidae, evolution has occurred in both directions according to whether the form lived among grass or on broad leaves with oblique lateral veins, and we can observe even now that the species with oblique stripes have longitudinal stripes when young, that is to say, while the stripes have no biological significance. The white places in the skin which gave rise, probably first as small spots, to this protective marking could be combined in one way or another according to the requirements of the species. They must therefore either have possessed selection-value from the first, or, if this was not the case at their earliest occurrence, there must have been SOME OTHER FACTORS which raised them to the point of selection-value. I shall return to this in discussing germinal selection. But the case may be followed still farther, and leads us to the same alternative on a still more secure basis. Many years ago I observed in caterpillars of Smerinthus populi (the poplar hawk-moth), which also possess white oblique stripes, that certain individuals showed RED SPOTS above these stripes; these spots occurred only on certain segments, and never flowed together to form continuous stripes. In another species (Smerinthus tiliae) similar blood-red spots unite to form a line-like coloured seam in the last stage of larval life, while in S. ocellata rust-red spots appear in individual caterpillars, but more rarely than in S. Populi, and they show no tendency to flow together. Thus we have here the origin of a new character, arising from small beginnings, at least in S. tiliae, in which species the coloured stripes are a normal specific character. In the other species, S. populi and S. ocellata, we find the beginnings of the same variation, in one more rarely than in the other, and we can imagine that, in the course of time, in these two species, coloured lines over the oblique stripes will arise. In any case these spots are the elements of variation, out of which coloured lines MAY be evolved, if they are combined in this direction through the agency of natural selection. In S. populi the spots are often small, but sometimes it seems as though several had united to form large spots. Whether a process of selection in this direction will arise in S. populi and S. ocellata, or whether it is now going on cannot be determined, since we cannot tell in advance what biological value the marking might have for these two species. It is conceivable that the spots may have no selection-value as far as these species are concerned, and may therefore disappear again in the course of phylogeny, or, on the other hand, that they may be changed in another direction, for instance towards imitation of the rust-red fungoid patches on poplar and willow leaves. In any case we may regard the smallest spots as the initial stages of variation, the larger as a cumulative summation of these. Therefore either these initial stages must already possess selection-value, or, as I said before: THERE MUST BE SOME OTHER REASON FOR THEIR CUMULATIVE SUMMATION. I should like to give one more example, in which we can infer, though we cannot directly observe, the initial stages. All the Holothurians or sea-cucumbers have in the skin calcareous bodies of different forms, usually thick and irregular, which make the skin tough and resistant. In a small group of them--the species of Synapta--the calcareous bodies occur in the form of delicate anchors of microscopic size. Up till 1897 these anchors, like many other delicate microscopic structures, were regarded as curiosities, as natural marvels. But a Swedish observer, Oestergren, has recently shown that they have a biological significance: they serve the footless Synapta as auxiliary organs of locomotion, since, when the body swells up in the act of creeping, they press firmly with their tips, which are embedded in the skin, against the substratum on which the animal creeps, and thus prevent slipping backwards. In other Holothurians this slipping is made impossible by the fixing of the tube-feet. The anchors act automatically, sinking their tips towards the ground when the corresponding part of the body thickens, and returning to the original position at an angle of 45 degrees to the upper surface when the part becomes thin again. The arms of the anchor do not lie in the same plane as the shaft, and thus the curve of the arms forms the outermost part of the anchor, and offers no further resistance to the gliding of the animal. Every detail of the anchor, the curved portion, the little teeth at the head, the arms, etc., can be interpreted in the most beautiful way, above all the form of the anchor itself, for the two arms prevent it from swaying round to the side. The position of the anchors, too, is definite and significant; they lie obliquely to the longitudinal axis of the animal, and therefore they act alike whether the animal is creeping backwards or forwards. Moreover, the tips would pierce through the skin if the anchors lay in the longitudinal direction. Synapta burrows in the sand; it first pushes in the thin anterior end, and thickens this again, thus enlarging the hole, then the anterior tentacles displace more sand, the body is worked in a little farther, and the process begins anew. In the first act the anchors are passive, but they begin to take an active share in the forward movement when the body is contracted again. Frequently the animal retains only the posterior end buried in the sand, and then the anchors keep it in position, and make rapid withdrawal possible. Thus we have in these apparently random forms of the calcareous bodies, complex adaptations in which every little detail as to direction, curve, and pointing is exactly determined. That they have selection-value in their present perfected form is beyond all doubt, since the animals are enabled by means of them to bore rapidly into the ground and so to escape from enemies. We do not know what the initial stages were, but we cannot doubt that the little improvements, which occurred as variations of the originally simple slimy bodies of the Holothurians, were preserved because they already possessed selection-value for the Synaptidae. For such minute microscopic structures whose form is so delicately adapted to the role they have to play in the life of the animal, cannot have arisen suddenly and as a whole, and every new variation of the anchor, that is, in the direction of the development of the two arms, and every curving of the shaft which prevented the tips from projecting at the wrong time, in short, every little adaptation in the modelling of the anchor must have possessed selection-value. And that such minute changes of form fall within the sphere of fluctuating variations, that is to say, THAT THEY OCCUR is beyond all doubt. In many of the Synaptidae the anchors are replaced by calcareous rods bent in the form of an S, which are said to act in the same way. Others, such as those of the genus Ankyroderma, have anchors which project considerably beyond the skin, and, according to Oestergren, serve "to catch plant-particles and other substances" and so mask the animal. Thus we see that in the Synaptidae the thick and irregular calcareous bodies of the Holothurians have been modified and transformed in various ways in adaptation to the footlessness of these animals, and to the peculiar conditions of their life, and we must conclude that the earlier stages of these changes presented themselves to the processes of selection in the form of microscopic variations. For it is as impossible to think of any origin other than through selection in this case as in the case of the toughness, and the "drip-tips" of tropical leaves. And as these last could not have been produced directly by the beating of the heavy rain-drops upon them, so the calcareous anchors of Synapta cannot have been produced directly by the friction of the sand and mud at the bottom of the sea, and, since they are parts whose function is PASSIVE the Lamarckian factor of use and disuse does not come into question. The conclusion is unavoidable, that the microscopically small variations of the calcareous bodies in the ancestral forms have been intensified and accumulated in a particular direction, till they have led to the formation of the anchor. Whether this has taken place by the action of natural selection alone, or whether the laws of variation and the intimate processes within the germ-plasm have cooperated will become clear in the discussion of germinal selection. This whole process of adaptation has obviously taken place within the time that has elapsed since this group of sea-cucumbers lost their tube-feet, those characteristic organs of locomotion which occur in no group except the Echinoderms, and yet have totally disappeared in the Synaptidae. And after all what would animals that live in sand and mud do with tube-feet? (c) COADAPTATION. Darwin pointed out that one of the essential differences between artificial and natural selection lies in the fact that the former can modify only a few characters, usually only one at a time, while Nature preserves in the struggle for existence all the variations of a species, at the same time and in a purely mechanical way, if they possess selection-value. Herbert Spencer, though himself an adherent of the theory of selection, declared in the beginning of the nineties that in his opinion the range of this principle was greatly over-estimated, if the great changes which have taken place in so many organisms in the course of ages are to be interpreted as due to this process of selection alone, since no transformation of any importance can be evolved by itself; it is always accompanied by a host of secondary changes. He gives the familiar example of the Giant Stag of the Irish peat, the enormous antlers of which required not only a much stronger skull cap, but also greater strength of the sinews, muscles, nerves and bones of the whole anterior half of the animal, if their mass was not to weigh down the animal altogether. It is inconceivable, he says, that so many processes of selection should take place SIMULTANEOUSLY, and we are therefore forced to fall back on the Lamarckian factor of the use and disuse of functional parts. And how, he asks, could natural selection follow two opposite directions of evolution in different parts of the body at the same time, as for instance in the case of the kangaroo, in which the forelegs must have become shorter, while the hind legs and the tail were becoming longer and stronger? Spencer's main object was to substantiate the validity of the Lamarckian principle, the cooperation of which with selection had been doubted by many. And it does seem as though this principle, if it operates in nature at all, offers a ready and simple explanation of all such secondary variations. Not only muscles, but nerves, bones, sinews, in short all tissues which function actively, increase in strength in proportion as they are used, and conversely they decrease when the claims on them diminish. All the parts, therefore, which depend on the part that varied first, as for instance the enlarged antlers of the Irish Elk, must have been increased or decreased in strength, in exact proportion to the claims made upon them,--just as is actually the case. But beautiful as this explanation would be, I regard it as untenable, because it assumes the TRANSMISSIBILITY OF FUNCTIONAL MODIFICATIONS (so-called "acquired" characters), and this is not only undemonstrable, but is scarcely theoretically conceivable, for the secondary variations which accompany or follow the first as correlative variations, occur also in cases in which the animals concerned are sterile and THEREFORE CANNOT TRANSMIT ANYTHING TO THEIR DESCENDANTS. This is true of WORKER BEES, and particularly of ANTS, and I shall here give a brief survey of the present state of the problem as it appears to me. Much has been written on both sides of this question since the published controversy on the subject in the nineties between Herbert Spencer and myself. I should like to return to the matter in detail, if the space at my disposal permitted, because it seems to me that the arguments I advanced at that time are equally cogent to-day, notwithstanding all the objections that have since been urged against them. Moreover, the matter is by no means one of subordinate interest; it is the very kernel of the whole question of the reality and value of the principle of selection. For if selection alone does not suffice to explain "HARMONIOUS ADAPTATION" as I have called Spencer's COADAPTATION, and if we require to call in the aid of the Lamarckian factor it would be questionable whether selection could explain any adaptations whatever. In this particular case--of worker bees--the Lamarckian factor may be excluded altogether, for it can be demonstrated that here at any rate the effects of use and disuse cannot be transmitted. But if it be asked why we are unwilling to admit the cooperation of the Darwinian factor of selection and the Lamarckian factor, since this would afford us an easy and satisfactory explanation of the phenomena, I answer: BECAUSE THE LAMARCKIAN PRINCIPLE IS FALLACIOUS, AND BECAUSE BY ACCEPTING IT WE CLOSE THE WAY TOWARDS DEEPER INSIGHT. It is not a spirit of combativeness or a desire for self-vindication that induces me to take the field once more against the Lamarckian principle, it is the conviction that the progress of our knowledge is being obstructed by the acceptance of this fallacious principle, since the facile explanation it apparently affords prevents our seeking after a truer explanation and a deeper analysis. The workers in the various species of ants are sterile, that is to say, they take no regular part in the reproduction of the species, although individuals among them may occasionally lay eggs. In addition to this they have lost the wings, and the receptaculum seminis, and their compound eyes have degenerated to a few facets. How could this last change have come about through disuse, since the eyes of workers are exposed to light in the same way as are those of the sexual insects and thus in this particular case are not liable to "disuse" at all? The same is true of the receptaculum seminis, which can only have been disused as far as its glandular portion and its stalk are concerned, and also of the wings, the nerves tracheae and epidermal cells of which could not cease to function until the whole wing had degenerated, for the chitinous skeleton of the wing does not function at all in the active sense. But, on the other hand, the workers in all species have undergone modifications in a positive direction, as, for instance, the greater development of brain. In many species large workers have evolved,--the so-called SOLDIERS, with enormous jaws and teeth, which defend the colony,--and in others there are SMALL workers which have taken over other special functions, such as the rearing of the young Aphides. This kind of division of the workers into two castes occurs among several tropical species of ants, but it is also present in the Italian species, Colobopsis truncata. Beautifully as the size of the jaws could be explained as due to the increased use made of them by the "soldiers," or the enlarged brain as due to the mental activities of the workers, the fact of the infertility of these forms is an insurmountable obstacle to accepting such an explanation. Neither jaws nor brain can have been evolved on the Lamarckian principle. The problem of coadaptation is no easier in the case of the ant than in the case of the Giant Stag. Darwin himself gave a pretty illustration to show how imposing the difference between the two kinds of workers in one species would seem if we translated it into human terms. In regard to the Driver ants (Anomma) we must picture to ourselves a piece of work, "for instance the building of a house, being carried on by two kinds of workers, of which one group was five feet four inches high, the other sixteen feet high." ("Origin of Species" (6th edition), page 232.) Although the ant is a small animal as compared with man or with the Irish Elk, the "soldier" with its relatively enormous jaws is hardly less heavily burdened than the Elk with its antlers, and in the ant's case, too, a strengthening of the skeleton, of the muscles, the nerves of the head, and of the legs must have taken place parallel with the enlargement of the jaws. HARMONIOUS ADAPTATION (coadaptation) has here been active in a high degree, and yet these "soldiers" are sterile! There thus remains nothing for it but to refer all their adaptations, positive and negative alike, to processes of selection which have taken place in the rudiments of the workers within the egg and sperm-cells of their parents. There is no way out of the difficulty except the one Darwin pointed out. He himself did not find the solution of the riddle at once. At first he believed that the case of the workers among social insects presented "the most serious special difficulty" in the way of his theory of natural selection; and it was only after it had become clear to him, that it was not the sterile insects themselves but their parents that were selected, according as they produced more or less well adapted workers, that he was able to refer to this very case of the conditions among ants "IN ORDER TO SHOW THE POWER OF NATURAL SELECTION" ("Origin of Species", page 233; see also edition 1, page 242.). He explains his view by a simple but interesting illustration. Gardeners have produced, by means of long continued artificial selection, a variety of Stock, which bears entirely double, and therefore infertile flowers (Ibid. page 230.). Nevertheless the variety continues to be reproduced from seed, because in addition to the double and infertile flowers, the seeds always produce a certain number of single, fertile blossoms, and these are used to reproduce the double variety. These single and fertile plants correspond "to the males and females of an ant-colony, the infertile plants, which are regularly produced in large numbers, to the neuter workers of the colony." This illustration is entirely apt, the only difference between the two cases consisting in the fact that the variation in the flower is not a useful, but a disadvantageous one, which can only be preserved by artificial selection on the part of the gardener, while the transformations that have taken place parallel with the sterility of the ants are useful, since they procure for the colony an advantage in the struggle for existence, and they are therefore preserved by natural selection. Even the sterility itself in this case is not disadvantageous, since the fertility of the true females has at the same time considerably increased. We may therefore regard the sterile forms of ants, which have gradually been adapted in several directions to varying functions, AS A CERTAIN PROOF that selection really takes place in the germ-cells of the fathers and mothers of the workers, and that SPECIAL COMPLEXES OF PRIMORDIA (IDS) are present in the workers and in the males and females, and these complexes contain the primordia of the individual parts (DETERMINANTS). But since all living entities vary, the determinants must also vary, now in a favourable, now in an unfavourable direction. If a female produces eggs, which contain favourably varying determinants in the worker-ids, then these eggs will give rise to workers modified in the favourable direction, and if this happens with many females, the colony concerned will contain a better kind of worker than other colonies. I digress here in order to give an account of the intimate processes, which, according to my view, take place within the germ-plasm, and which I have called "GERMINAL SELECTION." These processes are of importance since they form the roots of variation, which in its turn is the root of natural selection. I cannot here do more than give a brief outline of the theory in order to show how the Darwin-Wallace theory of selection has gained support from it. With others, I regard the minimal amount of substance which is contained within the nucleus of the germ-cells, in the form of rods, bands, or granules, as the GERM-SUBSTANCE or GERM-PLASM, and I call the individual granules IDS. There is always a multiplicity of such ids present in the nucleus, either occurring individually, or united in the form of rods or bands (chromosomes). Each id contains the primary constituents of a WHOLE individual, so that several ids are concerned in the development of a new individual. In every being of complex structure thousands of primary constituents must go to make up a single id; these I call DETERMINANTS, and I mean by this name very small individual particles, far below the limits of microscopic visibility, vital units which feed, grow, and multiply by division. These determinants control the parts of the developing embryo,--in what manner need not here concern us. The determinants differ among themselves, those of a muscle are differently constituted from those of a nerve-cell or a glandular cell, etc., and every determinant is in its turn made up of minute vital units, which I call BIOPHORS, or the bearers of life. According to my view, these determinants not only assimilate, like every other living unit, but they VARY in the course of their growth, as every living unit does; they may vary qualitatively if the elements of which they are composed vary, they may grow and divide more or less rapidly, and their variations give rise to CORRESPONDING variations of the organ, cell, or cell-group which they determine. That they are undergoing ceaseless fluctuations in regard to size and quality seems to me the inevitable consequence of their unequal nutrition; for although the germ-cell as a whole usually receives sufficient nutriment, minute fluctuations in the amount carried to different parts within the germ-plasm cannot fail to occur. Now, if a determinant, for instance of a sensory cell, receives for a considerable time more abundant nutriment than before, it will grow more rapidly--become bigger, and divide more quickly, and, later, when the id concerned develops into an embryo, this sensory cell will become stronger than in the parents, possibly even twice as strong. This is an instance of a HEREDITARY INDIVIDUAL VARIATION, arising from the germ. The nutritive stream which, according to our hypothesis, favours the determinant N by chance, that is, for reasons unknown to us, may remain strong for a considerable time, or may decrease again; but even in the latter case it is conceivable that the ascending movement of the determinant may continue, because the strengthened determinant now ACTIVELY nourishes itself more abundantly,--that is to say, it attracts the nutriment to itself, and to a certain extent withdraws it from its fellow-determinants. In this way, it may--as it seems to me--get into PERMANENT UPWARD MOVEMENT, AND ATTAIN A DEGREE OF STRENGTH FROM WHICH THERE IS NO FALLING BACK. Then positive or negative selection sets in, favouring the variations which are advantageous, setting aside those which are disadvantageous. In a similar manner a DOWNWARD variation of the determinants may take place, if its progress be started by a diminished flow of nutriment. The determinants which are weakened by this diminished flow will have less affinity for attracting nutriment because of their diminished strength, and they will assimilate more feebly and grow more slowly, unless chance streams of nutriment help them to recover themselves. But, as will presently be shown, a change of direction cannot take place at EVERY stage of the degenerative process. If a certain critical stage of downward progress be passed, even favourable conditions of food-supply will no longer suffice permanently to change the direction of the variation. Only two cases are conceivable; if the determinant corresponds to a USEFUL organ, only its removal can bring back the germ-plasm to its former level; therefore personal selection removes the id in question, with its determinants, from the germ-plasm, by causing the elimination of the individual in the struggle for existence. But there is another conceivable case; the determinants concerned may be those of an organ which has become USELESS, and they will then continue unobstructed, but with exceeding slowness, along the downward path, until the organ becomes vestigial, and finally disappears altogether. The fluctuations of the determinants hither and thither may thus be transformed into a lasting ascending or descending movement; and THIS IS THE CRUCIAL POINT OF THESE GERMINAL PROCESSES. This is not a fantastic assumption; we can read it in the fact of the degeneration of disused parts. USELESS ORGANS ARE THE ONLY ONES WHICH ARE NOT HELPED TO ASCEND AGAIN BY PERSONAL SELECTION, AND THEREFORE IN THEIR CASE ALONE CAN WE FORM ANY IDEA OF HOW THE PRIMARY CONSTITUENTS BEHAVE, WHEN THEY ARE SUBJECT SOLELY TO INTRA-GERMINAL FORCES. The whole determinant system of an id, as I conceive it, is in a state of continual fluctuation upwards and downwards. In most cases the fluctuations will counteract one another, because the passive streams of nutriment soon change, but in many cases the limit from which a return is possible will be passed, and then the determinants concerned will continue to vary in the same direction, till they attain positive or negative selection-value. At this stage personal selection intervenes and sets aside the variation if it is disadvantageous, or favours--that is to say, preserves--it if it is advantageous. Only THE DETERMINANT OF A USELESS ORGAN IS UNINFLUENCED BY PERSONAL SELECTION, and, as experience shows, it sinks downwards; that is, the organ that corresponds to it degenerates very slowly but uninterruptedly till, after what must obviously be an immense stretch of time, it disappears from the germ-plasm altogether. Thus we find in the fact of the degeneration of disused parts the proof that not all the fluctuations of a determinant return to equilibrium again, but that, when the movement has attained to a certain strength, it continues IN THE SAME DIRECTION. We have entire certainty in regard to this as far as the downward progress is concerned, and we must assume it also in regard to ascending variations, as the phenomena of artificial selection certainly justify us in doing. If the Japanese breeders were able to lengthen the tail feathers of the cock to six feet, it can only have been because the determinants of the tail-feathers in the germ-plasm had already struck out a path of ascending variation, and this movement was taken advantage of by the breeder, who continually selected for reproduction the individuals in which the ascending variation was most marked. For all breeding depends upon the unconscious selection of germinal variations. Of course these germinal processes cannot be proved mathematically, since we cannot actually see the play of forces of the passive fluctuations and their causes. We cannot say how great these fluctuations are, and how quickly or slowly, how regularly or irregularly they change. Nor do we know how far a determinant must be strengthened by the passive flow of the nutritive stream if it is to be beyond the danger of unfavourable variations, or how far it must be weakened passively before it loses the power of recovering itself by its own strength. It is no more possible to bring forward actual proofs in this case than it was in regard to the selection-value of the initial stages of an adaptation. But if we consider that all heritable variations must have their roots in the germ-plasm, and further, that when personal selection does not intervene, that is to say, in the case of parts which have become useless, a degeneration of the part, and therefore also of its determinant must inevitably take place; then we must conclude that processes such as I have assumed are running their course within the germ-plasm, and we can do this with as much certainty as we were able to infer, from the phenomena of adaptation, the selection-value of their initial stages. The fact of the degeneration of disused parts seems to me to afford irrefutable proof that the fluctuations within the germ-plasm ARE THE REAL ROOT OF ALL HEREDITARY VARIATION, and the preliminary condition for the occurrence of the Darwin-Wallace factor of selection. Germinal selection supplies the stones out of which personal selection builds her temples and palaces: ADAPTATIONS. The importance for the theory of the process of degeneration of disused parts cannot be over-estimated, especially when it occurs in sterile animal forms, where we are free from the doubt as to the alleged LAMARCKIAN FACTOR which is apt to confuse our ideas in regard to other cases. If we regard the variation of the many determinants concerned in the transformation of the female into the sterile worker as having come about through the gradual transformation of the ids into worker-ids, we shall see that the germ-plasm of the sexual ants must contain three kinds of ids, male, female, and worker ids, or if the workers have diverged into soldiers and nest-builders, then four kinds. We understand that the worker-ids arose because their determinants struck out a useful path of variation, whether upward or downward, and that they continued in this path until the highest attainable degree of utility of the parts determined was reached. But in addition to the organs of positive or negative selection-value, there were some which were indifferent as far as the success and especially the functional capacity of the workers was concerned: wings, ovarian tubes, receptaculum seminis, a number of the facets of the eye, perhaps even the whole eye. As to the ovarian tubes it is possible that their degeneration was an advantage for the workers, in saving energy, and if so selection would favour the degeneration; but how could the presence of eyes diminish the usefulness of the workers to the colony? or the minute receptaculum seminis, or even the wings? These parts have therefore degenerated BECAUSE THEY WERE OF NO FURTHER VALUE TO THE INSECT. But if selection did not influence the setting aside of these parts because they were neither of advantage nor of disadvantage to the species, then the Darwinian factor of selection is here confronted with a puzzle which it cannot solve alone, but which at once becomes clear when germinal selection is added. For the determinants of organs that have no further value for the organism, must, as we have already explained, embark on a gradual course of retrograde development. In ants the degeneration has gone so far that there are no wing-rudiments present in ANY species, as is the case with so many butterflies, flies, and locusts, but in the larvae the imaginal discs of the wings are still laid down. With regard to the ovaries, degeneration has reached different levels in different species of ants, as has been shown by the researches of my former pupil, Elizabeth Bickford. In many species there are twelve ovarian tubes, and they decrease from that number to one; indeed, in one species no ovarian tube at all is present. So much at least is certain from what has been said, that in this case EVERYTHING depends on the fluctuations of the elements of the germ-plasm. Germinal selection, here as elsewhere, presents the variations of the determinants, and personal selection favours or rejects these, or,--if it be a question of organs which have become useless,--it does not come into play at all, and allows the descending variation free course. It is obvious that even the problem of COADAPTATION IN STERILE ANIMALS can thus be satisfactorily explained. If the determinants are oscillating upwards and downwards in continual fluctuation, and varying more pronouncedly now in one direction now in the other, useful variations of every determinant will continually present themselves anew, and may, in the course of generations, be combined with one another in various ways. But there is one character of the determinants that greatly facilitates this complex process of selection, that, after a certain limit has been reached, they go on varying in the same direction. From this it follows that development along a path once struck out may proceed without the continual intervention of personal selection. This factor only operates, so to speak, at the beginning, when it selects the determinants which are varying in the right direction, and again at the end, when it is necessary to put a check upon further variation. In addition to this, enormously long periods have been available for all these adaptations, as the very gradual transition stages between females and workers in many species plainly show, and thus this process of transformation loses the marvellous and mysterious character that seemed at the first glance to invest it, and takes rank, without any straining, among the other processes of selection. It seems to me that, from the facts that sterile animal forms can adapt themselves to new vital functions, their superfluous parts degenerate, and the parts more used adapt themselves in an ascending direction, those less used in a descending direction, we must draw the conclusion that harmonious adaptation here comes about WITHOUT THE COOPERATION OF THE LAMARCKIAN PRINCIPLE. This conclusion once established, however, we have no reason to refer the thousands of cases of harmonious adaptation, which occur in exactly the same way among other animals or plants, to a principle, the ACTIVE INTERVENTION OF WHICH IN THE TRANSFORMATION OF SPECIES IS NOWHERE PROVED. WE DO NOT REQUIRE IT TO EXPLAIN THE FACTS, AND THEREFORE WE MUST NOT ASSUME IT. The fact of coadaptation, which was supposed to furnish the strongest argument against the principle of selection, in reality yields the clearest evidence in favour of it. We MUST assume it, BECAUSE NO OTHER POSSIBILITY OF EXPLANATION IS OPEN TO US, AND BECAUSE THESE ADAPTATIONS ACTUALLY EXIST, THAT IS TO SAY, HAVE REALLY TAKEN PLACE. With this conviction I attempted, as far back as 1894, when the idea of germinal selection had not yet occurred to me, to make "harmonious adaptation" (coadaptation) more easily intelligible in some way or other, and so I was led to the idea, which was subsequently expounded in detail by Baldwin, and Lloyd Morgan, and also by Osborn, and Gulick as ORGANIC SELECTION. It seemed to me that it was not necessary that all the germinal variations required for secondary variations should have occurred SIMULTANEOUSLY, since, for instance, in the case of the stag, the bones, muscles, sinews, and nerves would be incited by the increasing heaviness of the antlers to greater activity in THE INDIVIDUAL LIFE, and so would be strengthened. The antlers can only have increased in size by very slow degrees, so that the muscles and bones may have been able to keep pace with their growth in the individual life, until the requisite germinal variations presented themselves. In this way a disharmony between the increasing weight of the antlers and the parts which support and move them would be avoided, since time would be given for the appropriate germinal variations to occur, and so to set agoing the HEREDITARY variation of the muscles, sinews, and bones. ("The Effect of External Influences upon Development", Romanes Lecture, Oxford, 1894.) I still regard this idea as correct, but I attribute less importance to "organic selection" than I did at that time, in so far that I do not believe that it ALONE could effect complex harmonious adaptations. Germinal selection now seems to me to play the chief part in bringing about such adaptations. Something the same is true of the principle I have called "Panmixia". As I became more and more convinced, in the course of years, that the LAMARCKIAN PRINCIPLE ought not to be called in to explain the dwindling of disused parts, I believed that this process might be simply explained as due to the cessation of the conservative effect of natural selection. I said to myself that, from the moment in which a part ceases to be of use, natural selection withdraws its hand from it, and then it must inevitably fall from the height of its adaptiveness, because inferior variants would have as good a chance of persisting as better ones, since all grades of fitness of the part in question would be mingled with one another indiscriminately. This is undoubtedly true, as Romanes pointed out ten years before I did, and this mingling of the bad with the good probably does bring about a deterioration of the part concerned. But it cannot account for the steady diminution, which always occurs when a part is in process of becoming rudimentary, and which goes on until it ultimately disappears altogether. The process of dwindling cannot therefore be explained as due to panmixia alone; we can only find a sufficient explanation in germinal selection. IV. DERIVATIVES OF THE THEORY OF SELECTION. The impetus in all directions given by Darwin through his theory of selection has been an immeasurable one, and its influence is still felt. It falls within the province of the historian of science to enumerate all the ideas which, in the last quarter of the nineteenth century, grew out of Darwin's theories, in the endeavour to penetrate more deeply into the problem of the evolution of the organic world. Within the narrow limits to which this paper is restricted, I cannot attempt to discuss any of these. V. ARGUMENTS FOR THE REALITY OF THE PROCESSES OF SELECTION. (a) SEXUAL SELECTION. Sexual selection goes hand in hand with natural selection. From the very first I have regarded sexual selection as affording an extremely important and interesting corroboration of natural selection, but, singularly enough, it is precisely against this theory that an adverse judgment has been pronounced in so many quarters, and it is only quite recently, and probably in proportion as the wealth of facts in proof of it penetrates into a wider circle, that we seem to be approaching a more general recognition of this side of the problem of adaptation. Thus Darwin's words in his preface to the second edition (1874) of his book, "The Descent of Man and Sexual Selection", are being justified: "My conviction as to the operation of natural selection remains unshaken," and further, "If naturalists were to become more familiar with the idea of sexual selection, it would, I think, be accepted to a much greater extent, and already it is fully and favourably accepted by many competent judges." Darwin was able to speak thus because he was already acquainted with an immense mass of facts, which, taken together, yield overwhelming evidence of the validity of the principle of sexual selection. NATURAL SELECTION chooses out for reproduction the individuals that are best equipped for the struggle for existence, and it does so at every stage of development; it thus improves the species in all its stages and forms. SEXUAL SELECTION operates only on individuals that are already capable of reproduction, and does so only in relation to the attainment of reproduction. It arises from the rivalry of one sex, usually the male, for the possession of the other, usually the female. Its influence can therefore only DIRECTLY affect one sex, in that it equips it better for attaining possession of the other. But the effect may extend indirectly to the female sex, and thus the whole species may be modified, without, however, becoming any more capable of resistance in the struggle for existence, for sexual selection only gives rise to adaptations which are likely to give their possessor the victory over rivals in the struggle for possession of the female, and which are therefore peculiar to the wooing sex: the manifold "secondary sexual characters." The diversity of these characters is so great that I cannot here attempt to give anything approaching a complete treatment of them, but I should like to give a sufficient number of examples to make the principle itself, in its various modes of expression, quite clear. One of the chief preliminary postulates of sexual selection is the unequal number of individuals in the two sexes, for if every male immediately finds his mate there can be no competition for the possession of the female. Darwin has shown that, for the most part, the inequality between the sexes is due simply to the fact that there are more males than females, and therefore the males must take some pains to secure a mate. But the inequality does not always depend on the numerical preponderance of the males, it is often due to polygamy; for, if one male claims several females, the number of females in proportion to the rest of the males will be reduced. Since it is almost always the males that are the wooers, we must expect to find the occurrence of secondary sexual characters chiefly among them, and to find it especially frequent in polygamous species. And this is actually the case. If we were to try to guess--without knowing the facts--what means the male animals make use of to overcome their rivals in the struggle for the possession of the female, we might name many kinds of means, but it would be difficult to suggest any which is not actually employed in some animal group or other. I begin with the mere difference in strength, through which the male of many animals is so sharply distinguished from the female, as, for instance, the lion, walrus, "sea-elephant," and others. Among these the males fight violently for the possession of the female, who falls to the victor in the combat. In this simple case no one can doubt the operation of selection, and there is just as little room for doubt as to the selection-value of the initial stages of the variation. Differences in bodily strength are apparent even among human beings, although in their case the struggle for the possession of the female is no longer decided by bodily strength alone. Combats between male animals are often violent and obstinate, and the employment of the natural weapons of the species in this way has led to perfecting of these, e.g. the tusks of the boar, the antlers of the stag, and the enormous, antler-like jaws of the stag-beetle. Here again it is impossible to doubt that variations in these organs presented themselves, and that these were considerable enough to be decisive in combat, and so to lead to the improvement of the weapon. Among many animals, however, the females at first withdraw from the males; they are coy, and have to be sought out, and sometimes held by force. This tracking and grasping of the females by the males has given rise to many different characters in the latter, as, for instance, the larger eyes of the male bee, and especially of the males of the Ephemerids (May-flies), some species of which show, in addition to the usual compound eyes, large, so-called turban-eyes, so that the whole head is covered with seeing surfaces. In these species the females are very greatly in the minority (1-100), and it is easy to understand that a keen competition for them must take place, and that, when the insects of both sexes are floating freely in the air, an unusually wide range of vision will carry with it a decided advantage. Here again the actual adaptations are in accordance with the preliminary postulates of the theory. We do not know the stages through which the eye has passed to its present perfected state, but, since the number of simple eyes (facets) has become very much greater in the male than in the female, we may assume that their increase is due to a gradual duplication of the determinants of the ommatidium in the germ-plasm, as I have already indicated in regard to sense-organs in general. In this case, again, the selection-value of the initial stages hardly admits of doubt; better vision DIRECTLY secures reproduction. In many cases THE ORGAN OF SMELL shows a similar improvement. Many lower Crustaceans (Daphnidae) have better developed organs of smell in the male sex. The difference is often slight and amounts only to one or two olfactory filaments, but certain species show a difference of nearly a hundred of these filaments (Leptodora). The same thing occurs among insects. We must briefly consider the clasping or grasping organs which have developed in the males among many lower Crustaceans, but here natural selection plays its part along with sexual selection, for the union of the sexes is an indispensable condition for the maintenance of the species, and as Darwin himself pointed out, in many cases the two forms of selection merge into each other. This fact has always seemed to me to be a proof of natural selection, for, in regard to sexual selection, it is quite obvious that the victory of the best-equipped could have brought about the improvement only of the organs concerned, the factors in the struggle, such as the eye and the olfactory organ. We come now to the EXCITANTS; that is, to the group of sexual characters whose origin through processes of selection has been most frequently called in question. We may cite the LOVE-CALLS produced by many male insects, such as crickets and cicadas. These could only have arisen in animal groups in which the female did not rapidly flee from the male, but was inclined to accept his wooing from the first. Thus, notes like the chirping of the male cricket serve to entice the females. At first they were merely the signal which showed the presence of a male in the neighbourhood, and the female was gradually enticed nearer and nearer by the continued chirping. The male that could make himself heard to the greatest distance would obtain the largest following, and would transmit the beginnings, and, later, the improvement of his voice to the greatest number of descendants. But sexual excitement in the female became associated with the hearing of the love-call, and then the sound-producing organ of the male began to improve, until it attained to the emission of the long-drawn-out soft notes of the mole-cricket or the maenad-like cry of the cicadas. I cannot here follow the process of development in detail, but will call attention to the fact that the original purpose of the voice, the announcing of the male's presence, became subsidiary, and the exciting of the female became the chief goal to be aimed at. The loudest singers awakened the strongest excitement, and the improvement resulted as a matter of course. I conceive of the origin of bird-song in a somewhat similar manner, first as a means of enticing, then of exciting the female. One more kind of secondary sexual character must here be mentioned: the odour which emanates from so many animals at the breeding season. It is possible that this odour also served at first merely to give notice of the presence of individuals of the other sex, but it soon became an excitant, and as the individuals which caused the greatest degree of excitement were preferred, it reached as high a pitch of perfection as was possible to it. I shall confine myself here to the comparatively recently discovered fragrance of butterflies. Since Fritz Muller found out that certain Brazilian butterflies gave off fragrance "like a flower," we have become acquainted with many such cases, and we now know that in all lands, not only many diurnal Lepidoptera but nocturnal ones also give off a delicate odour, which is agreeable even to man. The ethereal oil to which this fragrance is due is secreted by the skin-cells, usually of the wing, as I showed soon after the discovery of the SCENT-SCALES. This is the case in the males; the females have no SPECIAL scent-scales recognisable as such by their form, but they must, nevertheless, give off an extremely delicate fragrance, although our imperfect organ of smell cannot perceive it, for the males become aware of the presence of a female, even at night, from a long distance off, and gather round her. We may therefore conclude, that both sexes have long given forth a very delicate perfume, which announced their presence to others of the same species, and that in many species (NOT IN ALL) these small beginnings became, in the males, particularly strong scent-scales of characteristic form (lute, brush, or lyre-shaped). At first these scales were scattered over the surface of the wing, but gradually they concentrated themselves, and formed broad, velvety bands, or strong, prominent brushes, and they attained their highest pitch of evolution when they became enclosed within pits or folds of the skin, which could be opened to let the delicious fragrance stream forth suddenly towards the female. Thus in this case also we see that characters, the original use of which was to bring the sexes together, and so to maintain the species, have been evolved in the males into means for exciting the female. And we can hardly doubt, that the females are most readily enticed to yield to the butterfly that sends out the strongest fragrance,--that is to say, that excites them to the highest degree. It is a pity that our organs of smell are not fine enough to examine the fragrance of male Lepidoptera in general, and to compare it with other perfumes which attract these insects. (See Poulton, "Essays on Evolution", 1908, pages 316, 317.) As far as we can perceive them they resemble the fragrance of flowers, but there are Lepidoptera whose scent suggests musk. A smell of musk is also given off by several plants: it is a sexual excitant in the musk-deer, the musk-sheep, and the crocodile. As far as we know, then, it is perfumes similar to those of flowers that the male Lepidoptera give off in order to entice their mates, and this is a further indication that animals, like plants, can to a large extent meet the claims made upon them by life, and produce the adaptations which are most purposive,--a further proof, too, of my proposition that the useful variations, so to speak, are ALWAYS THERE. The flowers developed the perfumes which entice their visitors, and the male Lepidoptera developed the perfumes which entice and excite their mates. There are many pretty little problems to be solved in this connection, for there are insects, such as some flies, that are attracted by smells which are unpleasant to us, like those from decaying flesh and carrion. But there are also certain flowers, some orchids for instance, which give forth no very agreeable odour, but one which is to us repulsive and disgusting; and we should therefore expect that the males of such insects would give off a smell unpleasant to us, but there is no case known to me in which this has been demonstrated. In cases such as we have discussed, it is obvious that there is no possible explanation except through selection. This brings us to the last kind of secondary sexual characters, and the one in regard to which doubt has been most frequently expressed,--decorative colours and decorative forms, the brilliant plumage of the male pheasant, the humming-birds, and the bird of Paradise, as well as the bright colours of many species of butterfly, from the beautiful blue of our little Lycaenidae to the magnificent azure of the large Morphinae of Brazil. In a great many cases, though not by any means in all, the male butterflies are "more beautiful" than the females, and in the Tropics in particular they shine and glow in the most superb colours. I really see no reason why we should doubt the power of sexual selection, and I myself stand wholly on Darwin's side. Even though we certainly cannot assume that the females exercise a conscious choice of the "handsomest" mate, and deliberate like the judges in a court of justice over the perfections of their wooers, we have no reason to doubt that distinctive forms (decorative feathers) and colours have a particularly exciting effect upon the female, just as certain odours have among animals of so many different groups, including the butterflies. The doubts which existed for a considerable time, as a result of fallacious experiments, as to whether the colours of flowers really had any influence in attracting butterflies have now been set at rest through a series of more careful investigations; we now know that the colours of flowers are there on account of the butterflies, as Sprengel first showed, and that the blossoms of Phanerogams are selected in relation to them, as Darwin pointed out. Certainly it is not possible to bring forward any convincing proof of the origin of decorative colours through sexual selection, but there are many weighty arguments in favour of it, and these form a body of presumptive evidence so strong that it almost amounts to certainty. In the first place, there is the analogy with other secondary sexual characters. If the song of birds and the chirping of the cricket have been evolved through sexual selection, if the penetrating odours of male animals,--the crocodile, the musk-deer, the beaver, the carnivores, and, finally, the flower-like fragrances of the butterflies have been evolved to their present pitch in this way, why should decorative colours have arisen in some other way? Why should the eye be less sensitive to SPECIFICALLY MALE colours and other VISIBLE signs ENTICING TO THE FEMALE, than the olfactory sense to specifically male odours, or the sense of hearing to specifically male sounds? Moreover, the decorative feathers of birds are almost always spread out and displayed before the female during courtship. I have elsewhere ("The Evolution Theory", London, 1904, I. page 219.) pointed out that decorative colouring and sweet-scentedness may replace one another in Lepidoptera as well as in flowers, for just as some modestly coloured flowers (mignonette and violet) have often a strong perfume, while strikingly coloured ones are sometimes quite devoid of fragrance, so we find that the most beautiful and gaily-coloured of our native Lepidoptera, the species of Vanessa, have no scent-scales, while these are often markedly developed in grey nocturnal Lepidoptera. Both attractions may, however, be combined in butterflies, just as in flowers. Of course, we cannot explain why both means of attraction should exist in one genus, and only one of them in another, since we do not know the minutest details of the conditions of life of the genera concerned. But from the sporadic distribution of scent-scales in Lepidoptera, and from their occurrence or absence in nearly related species, we may conclude that fragrance is a relatively MODERN acquirement, more recent than brilliant colouring. One thing in particular that stamps decorative colouring as a product of selection is ITS GRADUAL INTENSIFICATION by the addition of new spots, which we can quite well observe, because in many cases the colours have been first acquired by the males, and later transmitted to the females by inheritance. The scent-scales are never thus transmitted, probably for the same reason that the decorative colours of many birds are often not transmitted to the females: because with these they would be exposed to too great elimination by enemies. Wallace was the first to point out that in species with concealed nests the beautiful feathers of the male occurred in the female also, as in the parrots, for instance, but this is not the case in species which brood on an exposed nest. In the parrots one can often observe that the general brilliant colouring of the male is found in the female, but that certain spots of colour are absent, and these have probably been acquired comparatively recently by the male and have not yet been transmitted to the female. Isolation of the group of individuals which is in process of varying is undoubtedly of great value in sexual selection, for even a solitary conspicuous variation will become dominant much sooner in a small isolated colony, than among a large number of members of a species. Anyone who agrees with me in deriving variations from germinal selection will regard that process as an essential aid towards explaining the selection of distinctive courtship-characters, such as coloured spots, decorative feathers, horny outgrowths in birds and reptiles, combs, feather-tufts, and the like, since the beginnings of these would be presented with relative frequency in the struggle between the determinants within the germ-plasm. The process of transmission of decorative feathers to the female results, as Darwin pointed out and illustrated by interesting examples, in the COLOUR-TRANSFORMATION OF A WHOLE SPECIES, and this process, as the phyletically older colouring of young birds shows, must, in the course of thousands of years, have repeated itself several times in a line of descent. If we survey the wealth of phenomena presented to us by secondary sexual characters, we can hardly fail to be convinced of the truth of the principle of sexual selection. And certainly no one who has accepted natural selection should reject sexual selection, for, not only do the two processes rest upon the same basis, but they merge into one another, so that it is often impossible to say how much of a particular character depends on one and how much on the other form of selection. (b) NATURAL SELECTION. An actual proof of the theory of sexual selection is out of the question, if only because we cannot tell when a variation attains to selection-value. It is certain that a delicate sense of smell is of value to the male moth in his search for the female, but whether the possession of one additional olfactory hair, or of ten, or of twenty additional hairs leads to the success of its possessor we are unable to tell. And we are groping even more in the dark when we discuss the excitement caused in the female by agreeable perfumes, or by striking and beautiful colours. That these do make an impression is beyond doubt; but we can only assume that slight intensifications of them give any advantage, and we MUST assume this SINCE OTHERWISE SECONDARY SEXUAL CHARACTERS REMAIN INEXPLICABLE. The same thing is true in regard to natural selection. It is not possible to bring forward any actual proof of the selection-value of the initial stages, and the stages in the increase of variations, as has been already shown. But the selection-value of a finished adaptation can in many cases be statistically determined. Cesnola and Poulton have made valuable experiments in this direction. The former attached forty-five individuals of the green, and sixty-five of the brown variety of the praying mantis (Mantis religiosa), by a silk thread to plants, and watched them for seventeen days. The insects which were on a surface of a colour similar to their own remained uneaten, while twenty-five green insects on brown parts of plants had all disappeared in eleven days. The experiments of Poulton and Sanders ("Report of the British Association" (Bristol, 1898), London, 1899, pages 906-909.) were made with 600 pupae of Vanessa urticae, the "tortoise-shell butterfly." The pupae were artificially attached to nettles, tree-trunks, fences, walls, and to the ground, some at Oxford, some at St Helens in the Isle of Wight. In the course of a month 93 per cent of the pupae at Oxford were killed, chiefly by small birds, while at St Helens 68 per cent perished. The experiments showed very clearly that the colour and character of the surface on which the pupa rests--and thus its own conspicuousness--are of the greatest importance. At Oxford only the four pupae which were fastened to nettles emerged; all the rest--on bark, stones and the like--perished. At St Helens the elimination was as follows: on fences where the pupae were conspicuous, 92 per cent; on bark, 66 per cent; on walls, 54 per cent; and among nettles, 57 per cent. These interesting experiments confirm our views as to protective coloration, and show further, THAT THE RATIO OF ELIMINATION IN THE SPECIES IS A VERY HIGH ONE, AND THAT THEREFORE SELECTION MUST BE VERY KEEN. We may say that the process of selection follows as a logical necessity from the fulfilment of the three preliminary postulates of the theory: variability, heredity, and the struggle for existence, with its enormous ratio of elimination in all species. To this we must add a fourth factor, the INTENSIFICATION of variations which Darwin established as a fact, and which we are now able to account for theoretically on the basis of germinal selection. It may be objected that there is considerable uncertainty about this LOGICAL proof, because of our inability to demonstrate the selection-value of the initial stages and the individual stages of increase. We have therefore to fall back on PRESUMPTIVE EVIDENCE. This is to be found in THE INTERPRETATIVE VALUE OF THE THEORY. Let us consider this point in greater detail. In the first place, it is necessary to emphasise what is often overlooked, namely, that the theory not only explains the TRANSFORMATIONS of species, it also explains THEIR REMAINING THE SAME; in addition to the principle of varying, it contains within itself that of PERSISTING. It is part of the essence of selection, that it not only causes a part to VARY till it has reached its highest pitch of adaptation, but that it MAINTAINS IT AT THIS PITCH. THIS CONSERVING INFLUENCE OF NATURAL SELECTION is of great importance, and was early recognised by Darwin; it follows naturally from the principle of the survival of the fittest. We understand from this how it is that a species which has become fully adapted to certain conditions of life ceases to vary, but remains "constant," as long as the conditions of life FOR IT remain unchanged, whether this be for thousands of years, or for whole geological epochs. But the most convincing proof of the power of the principle of selection lies in the innumerable multitude of phenomena which cannot be explained in any other way. To this category belong all structures which are only PASSIVELY of advantage to the organism, because none of these can have arisen by the alleged LAMARCKIAN PRINCIPLE. These have been so often discussed that we need do no more than indicate them here. Until quite recently the sympathetic coloration of animals--for instance, the whiteness of Arctic animals--was referred, at least in part, to the DIRECT influence of external factors, but the facts can best be explained by referring them to the processes of selection, for then it is unnecessary to make the gratuitous assumption that many species are sensitive to the stimulus of cold and that others are not. The great majority of Arctic land-animals, mammals and birds, are white, and this proves that they were all able to present the variation which was most useful for them. The sable is brown, but it lives in trees, where the brown colouring protects and conceals it more effectively. The musk-sheep (Ovibos moschatus) is also brown, and contrasts sharply with the ice and snow, but it is protected from beasts of prey by its gregarious habit, and therefore it is of advantage to be visible from as great a distance as possible. That so many species have been able to give rise to white varieties does not depend on a special sensitiveness of the skin to the influence of cold, but to the fact that Mammals and Birds have a general tendency to vary towards white. Even with us, many birds--starlings, blackbirds, swallows, etc.--occasionally produce white individuals, but the white variety does not persist, because it readily falls a victim to the carnivores. This is true of white fawns, foxes, deer, etc. The whiteness, therefore, arises from internal causes, and only persists when it is useful. A great many animals living in a GREEN ENVIRONMENT have become clothed in green, especially insects, caterpillars, and Mantidae, both persecuted and persecutors. That it is not the direct effect of the environment which calls forth the green colour is shown by the many kinds of caterpillar which rest on leaves and feed on them, but are nevertheless brown. These feed by night and betake themselves through the day to the trunk of the tree, and hide in the furrows of the bark. We cannot, however, conclude from this that they were UNABLE to vary towards green, for there are Arctic animals which are white only in winter and brown in summer (Alpine hare, and the ptarmigan of the Alps), and there are also green leaf-insects which remain green only while they are young and difficult to see on the leaf, but which become brown again in the last stage of larval life, when they have outgrown the leaf. They then conceal themselves by day, sometimes only among withered leaves on the ground, sometimes in the earth itself. It is interesting that in one genus, Chaerocampa, one species is brown in the last stage of larval life, another becomes brown earlier, and in many species the last stage is not wholly brown, a part remaining green. Whether this is a case of a double adaptation, or whether the green is being gradually crowded out by the brown, the fact remains that the same species, even the same individual, can exhibit both variations. The case is the same with many of the leaf-like Orthoptera, as, for instance, the praying mantis (Mantis religiosa) which we have already mentioned. But the best proofs are furnished by those often-cited cases in which the insect bears a deceptive resemblance to another object. We now know many such cases, such as the numerous imitations of green or withered leaves, which are brought about in the most diverse ways, sometimes by mere variations in the form of the insect and in its colour, sometimes by an elaborate marking, like that which occurs in the Indian leaf-butterflies, Kallima inachis. In the single butterfly-genus Anaea, in the woods of South America, there are about a hundred species which are all gaily coloured on the upper surface, and on the reverse side exhibit the most delicate imitation of the colouring and pattern of a leaf, generally without any indication of the leaf-ribs, but extremely deceptive nevertheless. Anyone who has seen only one such butterfly may doubt whether many of the insignificant details of the marking can really be of advantage to the insect. Such details are for instance the apparent holes and splits in the apparently dry or half-rotten leaf, which are usually due to the fact that the scales are absent on a circular or oval patch so that the colourless wing-membrane lies bare, and one can look through the spot as through a window. Whether the bird which is seeking or pursuing the butterflies takes these holes for dewdrops, or for the work of a devouring insect, does not affect the question; the mirror-like spot undoubtedly increases the general deceptiveness, for the same thing occurs in many leaf-butterflies, though not in all, and in some cases it is replaced in quite a peculiar manner. In one species of Anaea (A. divina), the resting butterfly looks exactly like a leaf out of the outer edge of which a large semicircular piece has been eaten, possibly by a caterpillar; but if we look more closely it is obvious that there is no part of the wing absent, and that the semicircular piece is of a clear, pale yellow colour, while the rest of the wing is of a strongly contrasted dark brown. But the deceptive resemblance may be caused in quite a different manner. I have often speculated as to what advantage the brilliant white C could give to the otherwise dusky-coloured "Comma butterfly" (Grapta C. album). Poulton's recent observations ("Proc. Ent. Soc"., London, May 6, 1903.) have shown that this represents the imitation of a crack such as is often seen in dry leaves, and is very conspicuous because the light shines through it. The utility obviously lies in presenting to the bird the very familiar picture of a broken leaf with a clear shining slit, and we may conclude, from the imitation of such small details, that the birds are very sharp observers and that the smallest deviation from the usual arrests their attention and incites them to closer investigation. It is obvious that such detailed--we might almost say such subtle--deceptive resemblances could only have come about in the course of long ages through the acquirement from time to time of something new which heightened the already existing resemblance. In face of facts like these there can be no question of chance, and no one has succeeded so far in finding any other explanation to replace that by selection. For the rest, the apparent leaves are by no means perfect copies of a leaf; many of them only represent the torn or broken piece, or the half or two-thirds of a leaf, but then the leaves themselves frequently do not present themselves to the eye as a whole, but partially concealed among other leaves. Even those butterflies which, like the species of Kallima and Anaea, represent the whole of a leaf with stalk, ribs, apex, and the whole breadth, are not actual copies which would satisfy a botanist; there is often much wanting. In Kallima the lateral ribs of the leaf are never all included in the markings; there are only two or three on the left side and at most four or five on the right, and in many individuals these are rather obscure, while in others they are comparatively distinct. This furnishes us with fresh evidence in favour of their origin through processes of selection, for a botanically perfect picture could not arise in this way; there could only be a fixing of such details as heightened the deceptive resemblance. Our postulate of origin through selection also enables us to understand why the leaf-imitation is on the lower surface of the wing in the diurnal Lepidoptera, and on the upper surface in the nocturnal forms, corresponding to the attitude of the wings in the resting position of the two groups. The strongest of all proofs of the theory, however, is afforded by cases of true "mimicry," those adaptations discovered by Bates in 1861, consisting in the imitation of one species by another, which becomes more and more like its model. The model is always a species that enjoys some special protection from enemies, whether because it is unpleasant to taste, or because it is in some way dangerous. It is chiefly among insects and especially among butterflies that we find the greatest number of such cases. Several of these have been minutely studied, and every detail has been investigated, so that it is difficult to understand how there can still be disbelief in regard to them. If the many and exact observations which have been carefully collected and critically discussed, for instance by Poulton ("Essays on Evolution", 1889-1907, Oxford, 1908, passim, e.g. page 269.) were thoroughly studied, the arguments which are still frequently urged against mimicry would be found untenable; we can hardly hope to find more convincing proof of the actuality of the processes of selection than these cases put into our hands. The preliminary postulates of the theory of mimicry have been disputed, for instance, that diurnal butterflies are persecuted and eaten by birds, but observations specially directed towards this point in India, Africa, America and Europe have placed it beyond all doubt. If it were necessary I could myself furnish an account of my own observations on this point. In the same way it has been established by experiment and observation in the field that in all the great regions of distribution there are butterflies which are rejected by birds and lizards, their chief enemies, on account of their unpleasant smell or taste. These butterflies are usually gaily and conspicuously coloured and thus--as Wallace first interpreted it--are furnished with an easily recognisable sign: a sign of unpalatableness or WARNING COLOURS. If they were not thus recognisable easily and from a distance, they would frequently be pecked at by birds, and then rejected because of their unpleasant taste; but as it is, the insect-eaters recognise them at once as unpalatable booty and ignore them. Such IMMUNE (The expression does not refer to all the enemies of this butterfly; against ichneumon-flies, for instance, their unpleasant smell usually gives no protection.) species, wherever they occur, are imitated by other palatable species, which thus acquire a certain degree of protection. It is true that this explanation of the bright, conspicuous colours is only a hypothesis, but its foundations,--unpalatableness, and the liability of other butterflies to be eaten,--are certain, and its consequences--the existence of mimetic palatable forms--confirm it in the most convincing manner. Of the many cases now known I select one, which is especially remarkable, and which has been thoroughly investigated, Papilio dardanus (merope), a large, beautiful, diurnal butterfly which ranges from Abyssinia throughout the whole of Africa to the south coast of Cape Colony. The males of this form are everywhere ALMOST the same in colour and in form of wings, save for a few variations in the sparse black markings on the pale yellow ground. But the females occur in several quite different forms and colourings, and one of these only, the Abyssinian form, is like the male, while the other three or four are MIMETIC, that is to say, they copy a butterfly of quite a different family the Danaids, which are among the IMMUNE forms. In each region the females have thus copied two or three different immune species. There is much that is interesting to be said in regard to these species, but it would be out of keeping with the general tenor of this paper to give details of this very complicated case of polymorphism in P. dardanus. Anyone who is interested in the matter will find a full and exact statement of the case in as far as we know it, in Poulton's "Essays on Evolution" (pages 373-375). (Professor Poulton has corrected some wrong descriptions which I had unfortunately overlooked in the Plates of my book "Vortrage uber Descendenztheorie", and which refer to Papilio dardanus (merope). These mistakes are of no importance as far as and understanding of the mimicry-theory is concerned, but I hope shortly to be able to correct them in a later edition.) I need only add that three different mimetic female forms have been reared from the eggs of a single female in South Africa. The resemblance of these forms to their immune models goes so far that even the details of the LOCAL forms of the models are copied by the mimetic species. It remains to be said that in Madagascar a butterfly, Papilio meriones, occurs, of which both sexes are very similar in form and markings to the non-mimetic male of P. dardanus, so that it probably represents the ancestor of this latter species. In face of such facts as these every attempt at another explanation must fail. Similarly all the other details of the case fulfil the preliminary postulates of selection, and leave no room for any other interpretation. That the males do not take on the protective colouring is easily explained, because they are in general more numerous, and the females are more important for the preservation of the species, and must also live longer in order to deposit their eggs. We find the same state of things in many other species, and in one case (Elymnias undularis) in which the male is also mimetically coloured, it copies quite a differently coloured immune species from the model followed by the female. This is quite intelligible when we consider that if there were TOO MANY false immune types, the birds would soon discover that there were palatable individuals among those with unpalatable warning colours. Hence the imitation of different immune species by Papilio dardanus! I regret that lack of space prevents my bringing forward more examples of mimicry and discussing them fully. But from the case of Papilio dardanus alone there is much to be learnt which is of the highest importance for our understanding of transformations. It shows us chiefly what I once called, somewhat strongly perhaps, THE OMNIPOTENCE OF NATURAL SELECTION in answer to an opponent who had spoken of its "inadequacy." We here see that one and the same species is capable of producing four or five different patterns of colouring and marking; thus the colouring and marking are not, as has often been supposed, a necessary outcome of the specific nature of the species, but a true adaptation, which cannot arise as a direct effect of climatic conditions, but solely through what I may call the sorting out of the variations produced by the species, according to their utility. That caterpillars may be either green or brown is already something more than could have been expected according to the old conception of species, but that one and the same butterfly should be now pale yellow, with black; now red with black and pure white; now deep black with large, pure white spots; and again black with a large ochreous-yellow spot, and many small white and yellow spots; that in one sub-species it may be tailed like the ancestral form, and in another tailless like its Danaid model,--all this shows a far-reaching capacity for variation and adaptation that wide never have expected if we did not see the facts before us. How it is possible that the primary colour-variations should thus be intensified and combined remains a puzzle even now; we are reminded of the modern three-colour printing,--perhaps similar combinations of the primary colours take place in this case; in any case the direction of these primary variations is determined by the artist whom we know as natural selection, for there is no other conceivable way in which the model could affect the butterfly that is becoming more and more like it. The same climate surrounds all four forms of female; they are subject to the same conditions of nutrition. Moreover, Papilio dardanus is by no means the only species of butterfly which exhibits different kinds of colour-pattern on its wings. Many species of the Asiatic genus Elymnias have on the upper surface a very good imitation of an immune Euploeine (Danainae), often with a steel-blue ground-colour, while the under surface is well concealed when the butterfly is at rest,--thus there are two kinds of protective coloration each with a different meaning! The same thing may be observed in many non-mimetic butterflies, for instance in all our species of Vanessa, in which the under side shows a grey-brown or brownish-black protective coloration, but we do not yet know with certainty what may be the biological significance of the gaily coloured upper surface. In general it may be said that mimetic butterflies are comparatively rare species, but there are exceptions, for instance Limenitis archippus in North America, of which the immune model (Danaida plexippus) also occurs in enormous numbers. In another mimicry-category the imitators are often more numerous than the models, namely in the case of the imitation of DANGEROUS INSECTS by harmless species. Bees and wasps are dreaded for their sting, and they are copied by harmless flies of the genera Eristalis and Syrphus, and these mimics often occur in swarms about flowering plants without damage to themselves or to their models; they are feared and are therefore left unmolested. In regard also to the FAITHFULNESS OF THE COPY the facts are quite in harmony with the theory, according to which the resemblance must have arisen and increased BY DEGREES. We can recognise this in many cases, for even now the mimetic species show very VARYING DEGREES OF RESEMBLANCE to their immune model. If we compare, for instance, the many different imitators of Danaida chrysippus we find that, with their brownish-yellow ground-colour, and the position and size, and more or less sharp limitation of their clear marginal spots, they have reached very different degrees of nearness to their model. Or compare the female of Elymnias undularis with its model Danaida genutia; there is a general resemblance, but the marking of the Danaida is very roughly imitated in Elymnias. Another fact that bears out the theory of mimicry is, that even when the resemblance in colour-pattern is very great, the WING-VENATION, which is so constant, and so important in determining the systematic position of butterflies, is never affected by the variation. The pursuers of the butterfly have no time to trouble about entomological intricacies. I must not pass over a discovery of Poulton's which is of great theoretical importance--that mimetic butterflies may reach the same effect by very different means. ("Journ. Linn. Soc. London (Zool.)", Vol. XXVI. 1898, pages 598-602.) Thus the glass-like transparency of the wing of a certain Ithomiine (Methona) and its Pierine mimic (Dismorphia orise) depends on a diminution in the size of the scales; in the Danaine genus Ituna it is due to the fewness of the scales, and in a third imitator, a moth (Castnia linus var. heliconoides) the glass-like appearance of the wing is due neither to diminution nor to absence of scales, but to their absolute colourlessness and transparency, and to the fact that they stand upright. In another moth mimic (Anthomyza) the arrangement of the transparent scales is normal. Thus it is not some unknown external influence that has brought about the transparency of the wing in these five forms, as has sometimes been supposed. Nor is it a hypothetical INTERNAL evolutionary tendency, for all three vary in a different manner. The cause of this agreement can only lie in selection, which preserves and intensifies in each species the favourable variations that present themselves. The great faithfulness of the copy is astonishing in these cases, for it is not THE WHOLE wing which is transparent; certain markings are black in colour, and these contrast sharply with the glass-like ground. It is obvious that the pursuers of these butterflies must be very sharp-sighted, for otherwise the agreement between the species could never have been pushed so far. The less the enemies see and observe, the more defective must the imitation be, and if they had been blind, no visible resemblance between the species which required protection could ever have arisen. A seemingly irreconcilable contradiction to the mimicry theory is presented in the following cases, which were known to Bates, who, however, never succeeded in bringing them into line with the principle of mimicry. In South America there are, as we have already said, many mimics of the immune Ithomiinae (or as Bates called them Heliconidae). Among these there occur not merely species which are edible, and thus require the protection of a disguise, but others which are rejected on account of their unpalatableness. How could the Ithomiine dress have developed in their case, and of what use is it, since the species would in any case be immune? In Eastern Brazil, for instance, there are four butterflies, which bear a most confusing resemblance to one another in colour, marking, and form of wing, and all four are unpalatable to birds. They belong to four different genera and three sub-families, and we have to inquire: Whence came this resemblance and what end does it serve? For a long time no satisfactory answer could be found, but Fritz Muller (In "Kosmos", 1879, page 100.), seventeen years after Bates, offered a solution to the riddle, when he pointed out that young birds could not have an instinctive knowledge of the unpalatableness of the Ithomiines, but must learn by experience which species were edible and which inedible. Thus each young bird must have tasted at least one individual of each inedible species and discovered its unpalatability, before it learnt to avoid, and thus to spare the species. But if the four species resemble each other very closely the bird will regard them all as of the same kind, and avoid them all. Thus there developed a process of selection which resulted in the survival of the Ithomiine-like individuals, and in so great an increase of resemblance between the four species, that they are difficult to distinguish one from another even in a collection. The advantage for the four species, living side by side as they do e.g. in Bahia, lies in the fact that only one individual from the MIMICRY-RING ("inedible association") need be tasted by a young bird, instead of at least four individuals, as would otherwise be the case. As the number of young birds is great, this makes a considerable difference in the ratio of elimination. These interesting mimicry-rings (trusts), which have much significance for the theory, have been the subject of numerous and careful investigations, and at least their essential features are now fully established. Muller took for granted, without making any investigations, that young birds only learn by experience to distinguish between different kinds of victims. But Lloyd Morgan's ("Habit and Instinct", London, 1896.) experiments with young birds proved that this is really the case, and at the same time furnished an additional argument against the LAMARCKIAN PRINCIPLE. In addition to the mimicry-rings first observed in South America, others have been described from Tropical India by Moore, and by Poulton and Dixey from Africa, and we may expect to learn many more interesting facts in this connection. Here again the preliminary postulates of the theory are satisfied. And how much more that would lead to the same conclusion might be added! As in the case of mimicry many species have come to resemble one another through processes of selection, so we know whole classes of phenomena in which plants and animals have become adapted to one another, and have thus been modified to a considerable degree. I refer particularly to the relation between flowers and insects; but as there is an article on "The Biology of Flowers" in this volume, I need not discuss the subject, but will confine myself to pointing out the significance of these remarkable cases for the theory of selection. Darwin has shown that the originally inconspicuous blossoms of the phanerogams were transformed into flowers through the visits of insects, and that, conversely, several large orders of insects have been gradually modified by their association with flowers, especially as regards the parts of their body actively concerned. Bees and butterflies in particular have become what they are through their relation to flowers. In this case again all that is apparently contradictory to the theory can, on closer investigation, be beautifully interpreted in corroboration of it. Selection can give rise only to what is of use to the organism actually concerned, never to what is of use to some other organism, and we must therefore expect to find that in flowers only characters of use to THEMSELVES have arisen, never characters which are of use to insects only, and conversely that in the insects characters useful to them and not merely to the plants would have originated. For a long time it seemed as if an exception to this rule existed in the case of the fertilisation of the yucca blossoms by a little moth, Pronuba yuccasella. This little moth has a sickle-shaped appendage to its mouth-parts which occurs in no other Lepidopteron, and which is used for pushing the yellow pollen into the opening of the pistil, thus fertilising the flower. Thus it appears as if a new structure, which is useful only to the plant, has arisen in the insect. But the difficulty is solved as soon as we learn that the moth lays its eggs in the fruit-buds of the Yucca, and that the larvae, when they emerge, feed on the developing seeds. In effecting the fertilisation of the flower the moth is at the same time making provision for its own offspring, since it is only after fertilisation that the seeds begin to develop. There is thus nothing to prevent our referring this structural adaptation in Pronuba yuccasella to processes of selection, which have gradually transformed the maxillary palps of the female into the sickle-shaped instrument for collecting the pollen, and which have at the same time developed in the insect the instinct to press the pollen into the pistil. In this domain, then, the theory of selection finds nothing but corroboration, and it would be impossible to substitute for it any other explanation, which, now that the facts are so well known, could be regarded as a serious rival to it. That selection is a factor, and a very powerful factor in the evolution of organisms, can no longer be doubted. Even although we cannot bring forward formal proofs of it IN DETAIL, cannot calculate definitely the size of the variations which present themselves, and their selection-value, cannot, in short, reduce the whole process to a mathematical formula, yet we must assume selection, because it is the only possible explanation applicable to whole classes of phenomena, and because, on the other hand, it is made up of factors which we know can be proved actually to exist, and which, IF they exist, must of logical necessity cooperate in the manner required by the theory. WE MUST ACCEPT IT BECAUSE THE PHENOMENA OF EVOLUTION AND ADAPTATION MUST HAVE A NATURAL BASIS, AND BECAUSE IT IS THE ONLY POSSIBLE EXPLANATION OF THEM. (This has been discussed in many of my earlier works. See for instance "The All-Sufficiency of Natural Selection, a reply to Herbert Spencer", London, 1893.) Many people are willing to admit that selection explains adaptations, but they maintain that only a part of the phenomena are thus explained, because everything does not depend upon adaptation. They regard adaptation as, so to speak, a special effort on the part of Nature, which she keeps in readiness to meet particularly difficult claims of the external world on organisms. But if we look at the matter more carefully we shall find that adaptations are by no means exceptional, but that they are present everywhere in such enormous numbers, that it would be difficult in regard to any structure whatever, to prove that adaptation had NOT played a part in its evolution. How often has the senseless objection been urged against selection that it can create nothing, it can only reject. It is true that it cannot create either the living substance or the variations of it; both must be given. But in rejecting one thing it preserves another, intensifies it, combines it, and in this way CREATES what is new. EVERYTHING in organisms depends on adaptation; that is to say, everything must be admitted through the narrow door of selection, otherwise it can take no part in the building up of the whole. But, it is asked, what of the direct effect of external conditions, temperature, nutrition, climate and the like? Undoubtedly these can give rise to variations, but they too must pass through the door of selection, and if they cannot do this they are rejected, eliminated from the constitution of the species. It may, perhaps, be objected that such external influences are often of a compelling power, and that every animal MUST submit to them, and that thus selection has no choice and can neither select nor reject. There may be such cases; let us assume for instance that the effect of the cold of the Arctic regions was to make all the mammals become black; the result would be that they would all be eliminated by selection, and that no mammals would be able to live there at all. But in most cases a certain percentage of animals resists these strong influences, and thus selection secures a foothold on which to work, eliminating the unfavourable variation, and establishing a useful colouring, consistent with what is required for the maintenance of the species. Everything depends upon adaptation! We have spoken much of adaptation in colouring, in connection with the examples brought into prominence by Darwin, because these are conspicuous, easily verified, and at the same time convincing for the theory of selection. But is it only desert and polar animals whose colouring is determined through adaptation? Or the leaf-butterflies, and the mimetic species, or the terrifying markings, and "warning-colours" and a thousand other kinds of sympathetic colouring? It is, indeed, never the colouring alone which makes up the adaptation; the structure of the animal plays a part, often a very essential part, in the protective disguise, and thus MANY variations may cooperate towards ONE common end. And it is to be noted that it is by no means only external parts that are changed; internal parts are ALWAYS modified at the same time--for instance, the delicate elements of the nervous system on which depend the INSTINCT of the insect to hold its wings, when at rest, in a perfectly definite position, which, in the leaf-butterfly, has the effect of bringing the two pieces on which the marking occurs on the anterior and posterior wing into the same direction, and thus displaying as a whole the fine curve of the midrib on the seeming leaf. But the wing-holding instinct is not regulated in the same way in all leaf-butterflies; even our indigenous species of Vanessa, with their protective ground-colouring, have quite a distinctive way of holding their wings so that the greater part of the anterior wing is covered by the posterior when the butterfly is at rest. But the protective colouring appears on the posterior wing and on the tip of the anterior, TO PRECISELY THE DISTANCE TO WHICH IT IS LEFT UNCOVERED. This occurs, as Standfuss has shown, in different degree in our two most nearly allied species, the uncovered portion being smaller in V. urticae than in V. polychloros. In this case, as in most leaf-butterflies, the holding of the wing was probably the primary character; only after that was thoroughly established did the protective marking develop. In any case, the instinctive manner of holding the wings is associated with the protective colouring, and must remain as it is if the latter is to be effective. How greatly instincts may change, that is to say, may be adapted, is shown by the case of the Noctuid "shark" moth, Xylina vetusta. This form bears a most deceptive resemblance to a piece of rotten wood, and the appearance is greatly increased by the modification of the innate impulse to flight common to so many animals, which has here been transformed into an almost contrary instinct. This moth does not fly away from danger, but "feigns death," that is, it draws antennae, legs and wings close to the body, and remains perfectly motionless. It may be touched, picked up, and thrown down again, and still it does not move. This remarkable instinct must surely have developed simultaneously with the wood-colouring; at all events, both cooperating variations are now present, and prove that both the external and the most minute internal structure have undergone a process of adaptation. The case is the same with all structural variations of animal parts, which are not absolutely insignificant. When the insects acquired wings they must also have acquired the mechanism with which to move them--the musculature, and the nervous apparatus necessary for its automatic regulation. All instincts depend upon compound reflex mechanisms and are just as indispensable as the parts they have to set in motion, and all may have arisen through processes of selection if the reasons which I have elsewhere given for this view are correct. ("The Evolution Theory", London, 1904, page 144.) Thus there is no lack of adaptations within the organism, and particularly in its most important and complicated parts, so that we may say that there is no actively functional organ that has not undergone a process of adaptation relative to its function and the requirements of the organism. Not only is every gland structurally adapted, down to the very minutest histological details, to its function, but the function is equally minutely adapted to the needs of the body. Every cell in the mucous lining of the intestine is exactly regulated in its relation to the different nutritive substances, and behaves in quite a different way towards the fats, and towards nitrogenous substances, or peptones. I have elsewhere called attention to the many adaptations of the whale to the surrounding medium, and have pointed out--what has long been known, but is not universally admitted, even now--that in it a great number of important organs have been transformed in adaptation to the peculiar conditions of aquatic life, although the ancestors of the whale must have lived, like other hair-covered mammals, on land. I cited a number of these transformations--the fish-like form of the body, the hairlessness of the skin, the transformation of the fore-limbs to fins, the disappearance of the hind-limbs and the development of a tail fin, the layer of blubber under the skin, which affords the protection from cold necessary to a warm-blooded animal, the disappearance of the ear-muscles and the auditory passages, the displacement of the external nares to the forehead for the greater security of the breathing-hole during the brief appearance at the surface, and certain remarkable changes in the respiratory and circulatory organs which enable the animal to remain for a long time under water. I might have added many more, for the list of adaptations in the whale to aquatic life is by no means exhausted; they are found in the histological structure and in the minutest combinations in the nervous system. For it is obvious that a tail-fin must be used in quite a different way from a tail, which serves as a fly-brush in hoofed animals, or as an aid to springing in the kangaroo or as a climbing organ; it will require quite different reflex-mechanisms and nerve-combinations in the motor centres. I used this example in order to show how unnecessary it is to assume a special internal evolutionary power for the phylogenesis of species, for this whole order of whales is, so to speak, MADE UP OF ADAPTATIONS; it deviates in many essential respects from the usual mammalian type, and all the deviations are adaptations to aquatic life. But if precisely the most essential features of the organisation thus depend upon adaptation, what is left for a phyletic force to do, since it is these essential features of the structure it would have to determine? There are few people now who believe in a phyletic evolutionary power, which is not made up of the forces known to us--adaptation and heredity--but the conviction that EVERY part of an organism depends upon adaptation has not yet gained a firm footing. Nevertheless, I must continue to regard this conception as the correct one, as I have long done. I may be permitted one more example. The feather of a bird is a marvellous structure, and no one will deny that as a whole it depends upon adaptation. But what part of it DOES NOT depend upon adaptation? The hollow quill, the shaft with its hard, thin, light cortex, and the spongy substance within it, its square section compared with the round section of the quill, the flat barbs, their short, hooked barbules which, in the flight-feathers, hook into one another with just sufficient firmness to resist the pressure of the air at each wing-beat, the lightness and firmness of the whole apparatus, the elasticity of the vane, and so on. And yet all this belongs to an organ which is only passively functional, and therefore can have nothing to do with the LAMARCKIAN PRINCIPLE. Nor can the feather have arisen through some magical effect of temperature, moisture, electricity, or specific nutrition, and thus selection is again our only anchor of safety. But--it will be objected--the substance of which the feather consists, this peculiar kind of horny substance, did not first arise through selection in the course of the evolution of the birds, for it formed the covering of the scales of their reptilian ancestors. It is quite true that a similar substance covered the scales of the Reptiles, but why should it not have arisen among them through selection? Or in what other way could it have arisen, since scales are also passively useful parts? It is true that if we are only to call adaptation what has been acquired by the species we happen to be considering, there would remain a great deal that could not be referred to selection; but we are postulating an evolution which has stretched back through aeons, and in the course of which innumerable adaptations took place, which had not merely ephemeral persistence in a genus, a family or a class, but which was continued into whole Phyla of animals, with continual fresh adaptations to the special conditions of each species, family, or class, yet with persistence of the fundamental elements. Thus the feather, once acquired, persisted in all birds, and the vertebral column, once gained by adaptation in the lowest forms, has persisted in all the Vertebrates, from Amphioxus upwards, although with constant readaptation to the conditions of each particular group. Thus everything we can see in animals is adaptation, whether of to-day, or of yesterday, or of ages long gone by; every kind of cell, whether glandular, muscular, nervous, epidermic, or skeletal, is adapted to absolutely definite and specific functions, and every organ which is composed of these different kinds of cells contains them in the proper proportions, and in the particular arrangement which best serves the function of the organ; it is thus adapted to its function. All parts of the organism are tuned to one another, that is, THEY ARE ADAPTED TO ONE ANOTHER, and in the same way THE ORGANISM AS A WHOLE IS ADAPTED TO THE CONDITIONS OF ITS LIFE, AND IT IS SO AT EVERY STAGE OF ITS EVOLUTION. But all adaptations CAN be referred to selection; the only point that remains doubtful is whether they all MUST be referred to it. However that may be, whether the LAMARCKIAN PRINCIPLE is a factor that has cooperated with selection in evolution, or whether it is altogether fallacious, the fact remains, that selection is the cause of a great part of the phyletic evolution of organisms on our earth. Those who agree with me in rejecting the LAMARCKIAN PRINCIPLE will regard selection as the only GUIDING factor in evolution, which creates what is new out of the transmissible variations, by ordering and arranging these, selecting them in relation to their number and size, as the architect does his building-stones so that a particular style must result. ("Variation under Domestication", 1875 II. pages 426, 427.) But the building-stones themselves, the variations, have their basis in the influences which cause variation in those vital units which are handed on from one generation to another, whether, taken together they form the WHOLE organism, as in Bacteria and other low forms of life, or only a germ-substance, as in unicellular and multicellular organisms. (The Author and Editor are indebted to Professor Poulton for kindly assisting in the revision of the proof of this Essay.) IV. VARIATION. By HUGO DE VRIES. Professor of Botany in the University of Amsterdam. I. DIFFERENT KINDS OF VARIABILITY. Before Darwin, little was known concerning the phenomena of variability. The fact, that hardly two leaves on a tree were exactly the same, could not escape observation: small deviations of the same kind were met with everywhere, among individuals as well as among the organs of the same plant. Larger aberrations, spoken of as monstrosities, were for a long time regarded as lying outside the range of ordinary phenomena. A special branch of inquiry, that of Teratology, was devoted to them, but it constituted a science by itself, sometimes connected with morphology, but having scarcely any bearing on the processes of evolution and heredity. Darwin was the first to take a broad survey of the whole range of variations in the animal and vegetable kingdoms. His theory of Natural Selection is based on the fact of variability. In order that this foundation should be as strong as possible he collected all the facts, scattered in the literature of his time, and tried to arrange them in a scientific way. He succeeded in showing that variations may be grouped along a line of almost continuous gradations, beginning with simple differences in size and ending with monstrosities. He was struck by the fact that, as a rule, the smaller the deviations, the more frequently they appear, very abrupt breaks in characters being of rare occurrence. Among these numerous degrees of variability Darwin was always on the look out for those which might, with the greatest probability, be considered as affording material for natural selection to act upon in the development of new species. Neither of the extremes complied with his conceptions. He often pointed out, that there are a good many small fluctuations, which in this respect must be absolutely useless. On the other hand, he strongly combated the belief, that great changes would be necessary to explain the origin of species. Some authors had propounded the idea that highly adapted organs, e.g. the wings of a bird, could not have been developed in any other way than by a comparatively sudden modification of a well defined and important kind. Such a conception would allow of great breaks or discontinuity in the evolution of highly differentiated animals and plants, shortening the time for the evolution of the whole organic kingdom and getting over numerous difficulties inherent in the theory of slow and gradual progress. It would, moreover, account for the genetic relation of the larger groups of both animals and plants. It would, in a word, undoubtedly afford an easy means of simplifying the problem of descent with modification. Darwin, however, considered such hypotheses as hardly belonging to the domain of science; they belong, he said, to the realm of miracles. That species have a capacity for change is admitted by all evolutionists; but there is no need to invoke modifications other than those represented by ordinary variability. It is well known that in artificial selection this tendency to vary has given rise to numerous distinct races, and there is no reason for denying that it can do the same in nature, by the aid of natural selection. On both lines an advance may be expected with equal probability. His main argument, however, is that the most striking and most highly adapted modifications may be acquired by successive variations. Each of these may be slight, and they may affect different organs, gradually adapting them to the same purpose. The direction of the adaptations will be determined by the needs in the struggle for life, and natural selection will simply exclude all such changes as occur on opposite or deviating lines. In this way, it is not variability itself which is called upon to explain beautiful adaptations, but it is quite sufficient to suppose that natural selection has operated during long periods in the same way. Eventually, all the acquired characters, being transmitted together, would appear to us, as if they had all been simultaneously developed. Correlations must play a large part in such special evolutions: when one part is modified, so will be other parts. The distribution of nourishment will come in as one of the causes, the reactions of different organs to the same external influences as another. But no doubt the more effective cause is that of the internal correlations, which, however, are still but dimly understood. Darwin repeatedly laid great stress on this view, although a definite proof of its correctness could not be given in his time. Such proof requires the direct observation of a mutation, and it should be stated here that even the first observations made in this direction have clearly confirmed Darwin's ideas. The new evening primroses which have sprung in my garden from the old form of Oenothera Lamarckiana, and which have evidently been derived from it, in each case, by a single mutation, do not differ from their parent species in one character only, but in almost all their organs and qualities. Oenothera gigas, for example, has stouter stems and denser foliage; the leaves are larger and broader; its thick flower-buds produce gigantic flowers, but only small fruits with large seeds. Correlative changes of this kind are seen in all my new forms, and they lend support to the view that in the gradual development of highly adapted structures, analogous correlations may have played a large part. They easily explain large deviations from an original type, without requiring the assumption of too many steps. Monstrosities, as their name implies, are widely different in character from natural species; they cannot, therefore, be adduced as evidence in the investigation of the origin of species. There is no doubt that they may have much in common as regards their manner of origin, and that the origin of species, once understood, may lead to a better understanding of the monstrosities. But the reverse is not true, at least not as regards the main lines of development. Here, it is clear, monstrosities cannot have played a part of any significance. Reversions, or atavistic changes, would seem to give a better support to the theory of descent through modifications. These have been of paramount importance on many lines of evolution of the animal as well as of the vegetable kingdom. It is often assumed that monocotyledons are descended from some lower group of dicotyledons, probably allied to that which includes the buttercup family. On this view the monocotyledons must be assumed to have lost the cambium and all its influence on secondary growth, the differentiation of the flower into calyx and corolla, the second cotyledon or seed-leaf and several other characters. Losses of characters such as these may have been the result of abrupt changes, but this does not prove that the characters themselves have been produced with equal suddenness. On the contrary, Darwin shows very convincingly that a modification may well be developed by a series of steps, and afterwards suddenly disappear. Many monstrosities, such as those represented by twisted stems, furnish direct proofs in support of this view, since they are produced by the loss of one character and this loss implies secondary changes in a large number of other organs and qualities. Darwin criticises in detail the hypothesis of great and abrupt changes and comes to the conclusion that it does not give even a shadow of an explanation of the origin of species. It is as improbable as it is unnecessary. Sports and spontaneous variations must now be considered. It is well known that they have produced a large number of fine horticultural varieties. The cut-leaved maple and many other trees and shrubs with split leaves are known to have been produced at a single step; this is true in the case of the single-leaf strawberry plant and of the laciniate variety of the greater celandine: many white flowers, white or yellow berries and numerous other forms had a similar origin. But changes such as these do not come under the head of adaptations, as they consist for the most part in the loss of some quality or organ belonging to the species from which they were derived. Darwin thinks it impossible to attribute to this cause the innumerable structures, which are so well adapted to the habits of life of each species. At the present time we should say that such adaptations require progressive modifications, which are additions to the stock of qualities already possessed by the ancestors, and cannot, therefore, be explained on the ground of a supposed analogy with sports, which are for the most part of a retrogressive nature. Excluding all these more or less sudden changes, there remains a long series of gradations of variability, but all of these are not assumed by Darwin to be equally fit for the production of new species. In the first place, he disregards all mere temporary variations, such as size, albinism, etc.; further, he points out that very many species have almost certainly been produced by steps, not greater, and probably not very much smaller, than those separating closely related varieties. For varieties are only small species. Next comes the question of polymorphic species: their occurrence seems to have been a source of much doubt and difficulty in Darwin's mind, although at present it forms one of the main supports of the prevailing explanation of the origin of new species. Darwin simply states that this kind of variability seems to be of a peculiar nature; since polymorphic species are now in a stable condition their occurrence gives no clue as to the mode of origin of new species. Polymorphic species are the expression of the result of previous variability acting on a large scale; but they now simply consist of more or less numerous elementary species, which, as far as we know, do not at present exhibit a larger degree of variability than any other more uniform species. The vernal whitlow-grass (Draba verna) and the wild pansy are the best known examples; both have spread over almost the whole of Europe and are split up into hundreds of elementary forms. These sub-species show no signs of any extraordinary degree of variability, when cultivated under conditions necessary for the exclusion of inter-crossing. Hooker has shown, in the case of some ferns distributed over still wider areas, that the extinction of some of the intermediate forms in such groups would suffice to justify the elevation of the remaining types to the rank of distinct species. Polymorphic species may now be regarded as the link which unites ordinary variability with the historical production of species. But it does not appear that they had this significance for Darwin; and, in fact, they exhibit no phenomena which could explain the processes by which one species has been derived from another. By thus narrowing the limits of the species-producing variability Darwin was led to regard small deviations as the source from which natural selection derives material upon which to act. But even these are not all of the same type, and Darwin was well aware of the fact. It should here be pointed out that in order to be selected, a change must first have been produced. This proposition, which now seems self-evident, has, however, been a source of much difference of opinion among Darwin's followers. The opinion that natural selection produces changes in useful directions has prevailed for a long time. In other words, it was assumed that natural selection, by the simple means of singling out, could induce small and useful changes to increase and to reach any desired degree of deviation from the original type. In my opinion this view was never actually held by Darwin. It is in contradiction with the acknowledged aim of all his work,--the explanation of the origin of species by means of natural forces and phenomena only. Natural selection acts as a sieve; it does not single out the best variations, but it simply destroys the larger number of those which are, from some cause or another, unfit for their present environment. In this way it keeps the strains up to the required standard, and, in special circumstances, may even improve them. Returning to the variations which afford the material for the sieving-action of natural selection, we may distinguish two main kinds. It is true that the distinction between these was not clear at the time of Darwin, and that he was unable to draw a sharp line between them. Nevertheless, in many cases, he was able to separate them, and he often discussed the question which of the two would be the real source of the differentiation of species. Certain variations constantly occur, especially such as are connected with size, weight, colour, etc. They are usually too small for natural selection to act upon, having hardly any influence in the struggle for life: others are more rare, occurring only from time to time, perhaps once or twice in a century, perhaps even only once in a thousand years. Moreover, these are of another type, not simply affecting size, number or weight, but bringing about something new, which may be useful or not. Whenever the variation is useful natural selection will take hold of it and preserve it; in other cases the variation may either persist or disappear. In his criticism of miscellaneous objections brought forward against the theory of natural selection after the publication of the first edition of "The Origin of Species", Darwin stated his view on this point very clearly:--"The doctrine of natural selection or the survival of the fittest, which implies that when variations or individual differences of a beneficial nature happen to arise, these will be preserved." ("Origin of Species" (6th edition), page 169, 1882.) In this sentence the words "HAPPEN TO ARISE" appear to me of prominent significance. They are evidently due to the same general conception which prevailed in Darwin's Pangenesis hypothesis. (Cf. de Vries, "Intracellulare Pangenesis", page 73, Jena, 1889, and "Die Mutationstheorie", I. page 63. Leipzig, 1901.) A distinction is indicated between ordinary fluctuations which are always present, and such variations as "happen to arise" from time to time. ((I think it right to point out that the interpretation of this passage from the "Origin" by Professor de Vries is not accepted as correct either by Mr Francis Darwin or by myself. We do not believe that Darwin intended to draw any distinction between TWO TYPES of variation; the words "when variations or individual differences of a beneficial nature happen to arise" are not in our opinion meant to imply a distinction between ordinary fluctuations and variations which "happen to arise," but we believe that "or" is here used in the sense of ALIAS. With the permission of Professor de Vries, the following extract is quoted from a letter in which he replied to the objection raised to his reading of the passage in question: "As to your remarks on the passage on page 6, I agree that it is now impossible to see clearly how far Darwin went in his distinction of the different kinds of variability. Distinctions were only dimly guessed at by him. But in our endeavour to arrive at a true conception of his view I think that the chapter on Pangenesis should be our leading guide, and that we should try to interpret the more difficult passages by that chapter. A careful and often repeated study of the Pangenesis hypothesis has convinced me that Darwin, when he wrote that chapter, was well aware that ordinary variability has nothing to do with evolution, but that other kinds of variation were necessary. In some chapters he comes nearer to a clear distinction than in others. To my mind the expression 'happen to arise' is the sharpest indication of his inclining in this direction. I am quite convinced that numerous expressions in his book become much clearer when looked at in this way." The statement in this passage that "Darwin was well aware that ordinary variability has nothing to do with evolution, but that other kinds of variation were necessary" is contradicted by many passages in the "Origin". A.C.S.)) The latter afford the material for natural selection to act upon on the broad lines of organic development, but the first do not. Fortuitous variations are the species-producing kind, which the theory requires; continuous fluctuations constitute, in this respect, a useless type. Of late, the study of variability has returned to the recognition of this distinction. Darwin's variations, which from time to time happen to arise, are MUTATIONS, the opposite type being commonly designed fluctuations. A large mass of facts, collected during the last few decades, has confirmed this view, which in Darwin's time could only be expressed with much reserve, and everyone knows that Darwin was always very careful in statements of this kind. From the same chapter I may here cite the following paragraph: "Thus as I am inclined to believe, morphological differences,... such as the arrangement of the leaves, the divisions of the flower or of the ovarium, the position of the ovules, etc.--first appeared in many cases as fluctuating variations, which sooner or later became constant through the nature of the organism and of the surrounding conditions... but NOT THROUGH NATURAL SELECTION (The italics are mine (H. de V.).); for as these morphological characters do not affect the welfare of the species, any slight deviation in them could not have been governed or accumulated through this latter agency." ("Origin of Species" (6th edition), page 176.) We thus see that in Darwin's opinion, all small variations had not the same importance. In favourable circumstances some could become constant, but others could not. Since the appearance of the first edition of "The Origin of Species" fluctuating variability has been thoroughly studied by Quetelet. He discovered the law, which governs all phenomena of organic life falling under this head. It is a very simple law, and states that individual variations follow the laws of probability. He proved it, in the first place, for the size of the human body, using the measurements published for Belgian recruits; he then extended it to various other measurements of parts of the body, and finally concluded that it must be of universal validity for all organic beings. It must hold true for all characters in man, physical as well as intellectual and moral qualities; it must hold true for the plant kingdom as well as for the animal kingdom; in short, it must include the whole living world. Quetelet's law may be most easily studied in those cases where the variability relates to measure, number and weight, and a vast number of facts have since confirmed its exactness and its validity for all kinds of organisms, organs and qualities. But if we examine it more closely, we find that it includes just those minute variations, which, as Darwin repeatedly pointed out, have often no significance for the origin of species. In the phenomena, described by Quetelet's law nothing "happens to arise"; all is governed by the common law, which states that small deviations from the mean type are frequent, but that larger aberrations are rare, the rarer as they are larger. Any degree of variation will be found to occur, if only the number of individuals studied is large enough: it is even possible to calculate before hand, how many specimens must be compared in order to find a previously fixed degree of deviation. The variations, which from time to time happen to appear, are evidently not governed by this law. They cannot, as yet, be produced at will: no sowings of thousands or even of millions of plants will induce them, although by such means the chance of their occurring will obviously be increased. But they are known to occur, and to occur suddenly and abruptly. They have been observed especially in horticulture, where they are ranged in the large and ill-defined group called sports. Korschinsky has collected all the evidence which horticultural literature affords on this point. (S. Korschinsky, "Heterogenesis und Evolution", "Flora", Vol. LXXXIX. pages 240-363, 1901.) Several cases of the first appearance of a horticultural novelty have been recorded: this has always happened in the same way; it appeared suddenly and unexpectedly without any definite relation to previously existing variability. Dwarf types are one of the commonest and most favourite varieties of flowering plants; they are not originated by a repeated selection of the smallest specimens, but appear at once, without intermediates and without any previous indication. In many instances they are only about half the height of the original type, thus constituting obvious novelties. So it is in other cases described by Korschinsky: these sports or mutations are now recognised to be the main source of varieties of horticultural plants. As already stated, I do not pretend that the production of horticultural novelties is the prototype of the origin of new species in nature. I assume that they are, as a rule, derived from the parent species by the loss of some organ or quality, whereas the main lines of the evolution of the animal and vegetable kingdom are of course determined by progressive changes. Darwin himself has often pointed out this difference. But the saltatory origin of horticultural novelties is as yet the simplest parallel for natural mutations, since it relates to forms and phenomena, best known to the general student of evolution. The point which I wish to insist upon is this. The difference between small and ever present fluctuations and rare and more sudden variations was clear to Darwin, although the facts known at his time were too meagre to enable a sharp line to be drawn between these two great classes of variability. Since Darwin's time evidence, which proves the correctness of his view, has accumulated with increasing rapidity. Fluctuations constitute one type; they are never absent and follow the law of chance, but they do not afford the material from which to build new species. Mutations, on the other hand, only happen to occur from time to time. They do not necessarily produce greater changes than fluctuations, but such as may become, or rather are from their very nature, constant. It is this constancy which is the mark of specific characters, and on this basis every new specific character may be assumed to have arisen by mutation. Some authors have tried to show that the theory of mutation is opposed to Darwin's views. But this is erroneous. On the contrary, it is in fullest harmony with the great principle laid down by Darwin. In order to be acted upon by that complex of environmental forces, which Darwin has called natural selection, the changes must obviously first be there. The manner in which they are produced is of secondary importance and has hardly any bearing on the theory of descent with modification. ("Life and Letters" II. 125.) A critical survey of all the facts of variability of plants in nature as well as under cultivation has led me to the conviction, that Darwin was right in stating that those rare beneficial variations, which from time to time happen to arise,--the now so-called mutations--are the real source of progress in the whole realm of the organic world. II. EXTERNAL AND INTERNAL CAUSES OF VARIABILITY. All phenomena of animal and plant life are governed by two sets of causes; one of these is external, the other internal. As a rule the internal causes determine the nature of a phenomenon--what an organism can do and what it cannot do. The external causes, on the other hand, decide when a certain variation will occur, and to what extent its features may be developed. As a very clear and wholly typical instance I cite the cocks-combs (Celosia). This race is distinguished from allied forms by its faculty of producing the well-known broad and much twisted combs. Every single individual possesses this power, but all individuals do not exhibit it in its most complete form. In some cases this faculty may not be exhibited at the top of the main stem, although developed in lateral branches: in others it begins too late for full development. Much depends upon nourishment and cultivation, but almost always the horticulturist has to single out the best individuals and to reject those which do not come up to the standard. The internal causes are of a historical nature. The external ones may be defined as nourishment and environment. In some cases nutrition is the main factor, as, for instance, in fluctuating variability, but in natural selection environment usually plays the larger part. The internal or historical causes are constant during the life-time of a species, using the term species in its most limited sense, as designating the so-called elementary species or the units out of which the ordinary species are built up. These historical causes are simply the specific characters, since in the origin of a species one or more of these must have been changed, thus producing the characters of the new type. These changes must, of course, also be due partly to internal and partly to external causes. In contrast to these changes of the internal causes, the ordinary variability which is exhibited during the life-time of a species is called fluctuating variability. The name mutations or mutating variability is then given to the changes in the specific characters. It is desirable to consider these two main divisions of variability separately. In the case of fluctuations the internal causes, as well as the external ones, are often apparent. The specific characters may be designated as the mean about which the observed forms vary. Almost every character may be developed to a greater or a less degree, but the variations of the single characters producing a small deviation from the mean are usually the commonest. The limits of these fluctuations may be called wide or narrow, according to the way we look at them, but in numerous cases the extreme on the favoured side hardly surpasses double the value of that on the other side. The degree of this development, for every individual and for every organ, is dependent mainly on nutrition. Better nourishment or an increased supply of food produces a higher development; only it is not always easy to determine which direction is the fuller and which is the poorer one. The differences among individuals grown from different seeds are described as examples of individual variability, but those which may be observed on the same plant, or on cuttings, bulbs or roots derived from one individual are referred to as cases of partial variability. Partial variability, therefore, determines the differences among the flowers, fruits, leaves or branches of one individual: in the main, it follows the same laws as individual variability, but the position of a branch on a plant also determines its strength, and the part it may take in the nourishment of the whole. Composite flowers and umbels therefore have, as a rule, fewer rays on weak branches than on the strong main ones. The number of carpels in the fruits of poppies becomes very small on the weak lateral branches, which are produced towards the autumn, as well as on crowded, and therefore on weakened individuals. Double flowers follow the same rule, and numerous other instances could easily be adduced. Mutating variability occurs along three main lines. Either a character may disappear, or, as we now say, become latent; or a latent character may reappear, reproducing thereby a character which was once prominent in more or less remote ancestors. The third and most interesting case is that of the production of quite new characters which never existed in the ancestors. Upon this progressive mutability the main development of the animal and vegetable kingdom evidently depends. In contrast to this, the two other cases are called retrogressive and degressive mutability. In nature retrogressive mutability plays a large part; in agriculture and in horticulture it gives rise to numerous varieties, which have in the past been preserved, either on account of their usefulness or beauty, or simply as fancy-types. In fact the possession of numbers of varieties may be considered as the main character of domesticated animals and cultivated plants. In the case of retrogressive and degressive mutability the internal cause is at once apparent, for it is this which causes the disappearance or reappearance of some character. With progressive mutations the case is not so simple, since the new character must first be produced and then displayed. These two processes are theoretically different, but they may occur together or after long intervals. The production of the new character I call premutation, and the displaying mutation. Both of course must have their external as well as their internal causes, as I have repeatedly pointed out in my work on the Mutation Theory. ("Die Mutationstheorie", 2 vols., Leipzig, 1901.) It is probable that nutrition plays as important a part among the external causes of mutability as it does among those of fluctuating variability. Observations in support of this view, however, are too scanty to allow of a definite judgment. Darwin assumed an accumulative influence of external causes in the case of the production of new varieties or species. The accumulation might be limited to the life-time of a single individual, or embrace that of two or more generations. In the end a degree of instability in the equilibrium of one or more characters might be attained, great enough for a character to give way under a small shock produced by changed conditions of life. The character would then be thrown over from the old state of equilibrium into a new one. Characters which happen to be in this state of unstable equilibrium are called mutable. They may be either latent or active, being in the former case derived from old active ones or produced as new ones (by the process, designated premutation). They may be inherited in this mutable condition during a long series of generations. I have shown that in the case of the evening primrose of Lamarck this state of mutability must have existed for at least half a century, for this species was introduced from Texas into England about the year 1860, and since then all the strains derived from its first distribution over the several countries of Europe show the same phenomena in producing new forms. The production of the dwarf evening primrose, or Oenothera nanella, is assumed to be due to one of the factors, which determines the tall stature of the parent form, becoming latent; this would, therefore, afford an example of retrogressive mutation. Most of the other types of my new mutants, on the other hand, seem to be due to progressive mutability. The external causes of this curious period of mutability are as yet wholly unknown and can hardly be guessed at, since the origin of the Oenothera Lamarckiana is veiled in mystery. The seeds, introduced into England about 1860, were said to have come from Texas, but whether from wild or from cultivated plants we do not know. Nor has the species been recorded as having been observed in the wild condition. This, however, is nothing peculiar. The European types of Oenothera biennis and O. muricata are in the same condition. The first is said to have been introduced from Virginia, and the second from Canada, but both probably from plants cultivated in the gardens of these countries. Whether the same elementary species are still growing on those spots is unknown, mainly because the different sub-species of the species mentioned have not been systematically studied and distinguished. The origin of new species, which is in part the effect of mutability, is, however, due mainly to natural selection. Mutability provides the new characters and new elementary species. Natural selection, on the other hand, decides what is to live and what to die. Mutability seems to be free, and not restricted to previously determined lines. Selection, however, may take place along the same main lines in the course of long geological epochs, thus directing the development of large branches of the animal and vegetable kingdom. In natural selection it is evident that nutrition and environment are the main factors. But it is probable that, while nutrition may be one of the main causes of mutability, environment may play the chief part in the decisions ascribed to natural selection. Relations to neighbouring plants and to injurious or useful animals, have been considered the most important determining factors ever since the time when Darwin pointed out their prevailing influence. From this discussion of the main causes of variability we may derive the proposition that the study of every phenomenon in the field of heredity, of variability, and of the origin of new species will have to be considered from two standpoints; on one hand we have the internal causes, on the other the external ones. Sometimes the first are more easily detected, in other cases the latter are more accessible to investigation. But the complete elucidation of any phenomenon of life must always combine the study of the influence of internal with that of external causes. III. POLYMORPHIC VARIABILITY IN CEREALS. One of the propositions of Darwin's theory of the struggle for life maintains that the largest amount of life can be supported on any area, by great diversification or divergence in the structure and constitution of its inhabitants. Every meadow and every forest affords a proof of this thesis. The numerical proportion of the different species of the flora is always changing according to external influences. Thus, in a given meadow, some species will flower abundantly in one year and then almost disappear, until, after a series of years, circumstances allow them again to multiply rapidly. Other species, which have taken their places, will then become rare. It follows from this principle, that notwithstanding the constantly changing conditions, a suitable selection from the constituents of a meadow will ensure a continued high production. But, although the principle is quite clear, artificial selection has, as yet, done very little towards reaching a really high standard. The same holds good for cereals. In ordinary circumstances a field will give a greater yield, if the crop grown consists of a number of sufficiently differing types. Hence it happens that almost all older varieties of wheat are mixtures of more or less diverging forms. In the same variety the numerical composition will vary from year to year, and in oats this may, in bad years, go so far as to destroy more than half of the harvest, the wind-oats (Avena fatua), which scatter their grain to the winds as soon as it ripens, increasing so rapidly that they assume the dominant place. A severe winter, a cold spring and other extreme conditions of life will destroy one form more completely than another, and it is evident that great changes in the numerical composition of the mixture may thus be brought about. This mixed condition of the common varieties of cereals was well known to Darwin. For him it constituted one of the many types of variability. It is of that peculiar nature to which, in describing other groups, he applies the term polymorphy. It does not imply that the single constituents of the varieties are at present really changing their characters. On the other hand, it does not exclude the possibility of such changes. It simply states that observation shows the existence of different forms; how these have originated is a question which it does not deal with. In his well-known discussion of the variability of cereals, Darwin is mainly concerned with the question, whether under cultivation they have undergone great changes or only small ones. The decision ultimately depends on the question, how many forms have originally been taken into cultivation. Assuming five or six initial species, the variability must be assumed to have been very large, but on the assumption that there were between ten and fifteen types, the necessary range of variability is obviously much smaller. But in regard to this point, we are of course entirely without historical data. Few of the varieties of wheat show conspicuous differences, although their number is great. If we compare the differentiating characters of the smaller types of cereals with those of ordinary wild species, even within the same genus or family, they are obviously much less marked. All these small characters, however, are strictly inherited, and this fact makes it very probable that the less obvious constituents of the mixtures in ordinary fields must be constant and pure as long as they do not intercross. Natural crossing is in most cereals a phenomenon of rare occurrence, common enough to admit of the production of all possible hybrid combinations, but requiring the lapse of a long series of years to reach its full effect. Darwin laid great stress on this high amount of variability in the plants of the same variety, and illustrated it by the experience of Colonel Le Couteur ("On the Varieties, Properties, and Classification of Wheat", Jersey, 1837.) on his farm on the isle of Jersey, who cultivated upwards of 150 varieties of wheat, which he claimed were as pure as those of any other agriculturalist. But Professor La Gasca of Madrid, who visited him, drew attention to aberrant ears, and pointed out, that some of them might be better yielders than the majority of plants in the crop, whilst others might be poor types. Thence he concluded that the isolation of the better ones might be a means of increasing his crops. Le Couteur seems to have considered the constancy of such smaller types after isolation as absolutely probable, since he did not even discuss the possibility of their being variable or of their yielding a changeable or mixed progeny. This curious fact proves that he considered the types, discovered in his fields by La Gasca to be of the same kind as his other varieties, which until that time he had relied upon as being pure and uniform. Thus we see, that for him, the variability of cereals was what we now call polymorphy. He looked through his fields for useful aberrations, and collected twenty-three new types of wheat. He was, moreover, clear about one point, which, on being rediscovered after half a century, has become the starting-point for the new Swedish principle of selecting agricultural plants. It was the principle of single-ear sowing, instead of mixing the grains of all the selected ears together. By sowing each ear on a separate plot he intended not only to multiply them, but also to compare their value. This comparison ultimately led him to the choice of some few valuable sorts, one of which, the "Bellevue de Talavera," still holds its place among the prominent sorts of wheat cultivated in France. This variety seems to be really a uniform type, a quality very useful under favourable conditions of cultivation, but which seems to have destroyed its capacity for further improvement by selection. The principle of single-ear sowing, with a view to obtain pure and uniform strains without further selection, has, until a few years ago, been almost entirely lost sight of. Only a very few agriculturists have applied it: among these are Patrick Shirreff ("Die Verbesserung der Getreide-Arten", translated by R. Hesse, Halle, 1880.) in Scotland and Willet M. Hays ("Wheat, varieties, breeding, cultivation", Univ. Minnesota, Agricultural Experimental Station, Bull. no. 62, 1899.) in Minnesota. Patrick Shirreff observed the fact, that in large fields of cereals, single plants may from time to time be found with larger ears, which justify the expectation of a far greater yield. In the course of about twenty-five years he isolated in this way two varieties of wheat and two of oats. He simply multiplied them as fast as possible, without any selection, and put them on the market. Hays was struck by the fact that the yield of wheat in Minnesota was far beneath that in the neighbouring States. The local varieties were Fife and Blue Stem. They gave him, on inspection, some better specimens, "phenomenal yielders" as he called them. These were simply isolated and propagated, and, after comparison with the parent-variety and with some other selected strains of less value, were judged to be of sufficient importance to be tested by cultivation all over the State of Minnesota. They have since almost supplanted the original types, at least in most parts of the State, with the result that the total yield of wheat in Minnesota is said to have been increased by about a million dollars yearly. Definite progress in the method of single-ear sowing has, however, been made only recently. It had been foreshadowed by Patrick Shirreff, who after the production of the four varieties already mentioned, tried to carry out his work on a larger scale, by including numerous minor deviations from the main type. He found by doing so that the chances of obtaining a better form were sufficiently increased to justify the trial. But it was Nilsson who discovered the almost inexhaustible polymorphy of cereals and other agricultural crops and made it the starting-point for a new and entirely trustworthy method of the highest utility. By this means he has produced during the last fifteen years a number of new and valuable races, which have already supplanted the old types on numerous farms in Sweden and which are now being introduced on a large scale into Germany and other European countries. It is now twenty years since the station at Svalof was founded. During the first period of its work, embracing about five years, selection was practised on the principle which was then generally used in Germany. In order to improve a race a sample of the best ears was carefully selected from the best fields of the variety. These ears were considered as representatives of the type under cultivation, and it was assumed that by sowing their grains on a small plot a family could be obtained, which could afterwards be improved by a continuous selection. Differences between the collected ears were either not observed or disregarded. At Svalof this method of selection was practised on a far larger scale than on any German farm, and the result was, broadly speaking, the same. This may be stated in the following words: improvement in a few cases, failure in all the others. Some few varieties could be improved and yielded excellent new types, some of which have since been introduced into Swedish agriculture and are now prominent races in the southern and middle parts of the country. But the station had definite aims, and among them was the improvement of the Chevalier barley. This, in Middle Sweden, is a fine brewer's barley, but liable to failure during unfavourable summers on account of its slender stems. It was selected with a view of giving it stiffer stems, but in spite of all the care and work bestowed upon it no satisfactory result was obtained. This experience, combined with a number of analogous failures, could not fail to throw doubt upon the whole method. It was evident that good results were only exceptions, and that in most cases the principle was not one that could be relied upon. The exceptions might be due to unknown causes, and not to the validity of the method; it became therefore of much more interest to search for the causes than to continue the work along these lines. In the year 1892 a number of different varieties of cereals were cultivated on a large scale and a selection was again made from them. About two hundred samples of ears were chosen, each apparently constituting a different type. Their seeds were sown on separate plots and manured and treated as much as possible in the same manner. The plots were small and arranged in rows so as to facilitate the comparison of allied types. During the whole period of growth and during the ripening of the ears the plots were carefully studied and compared: they were harvested separately; ears and kernels were counted and weighed, and notes were made concerning layering, rust and other cereal pests. The result of this experiment was, in the main, no distinct improvement. Nilsson was especially struck by the fact that the plots, which should represent distinct types, were far from uniform. Many of them were as multiform as the fields from which the parent-ears were taken. Others showed variability in a less degree, but in almost all of them it was clear that a pure race had not been obtained. The experiment was a fair one, inasmuch as it demonstrated the polymorphic variability of cereals beyond all doubt and in a degree hitherto unsuspected; but from the standpoint of the selectionist it was a failure. Fortunately there were, however, one or two exceptions. A few lots showed a perfect uniformity in regard to all the stalks and ears: these were small families. This fact suggested the idea that each might have been derived from a single ear. During the selection in the previous summer, Nilsson had tried to find as many ears as possible of each new type which he recognised in his fields. But the variability of his crops was so great, that he was rarely able to include more than two or three ears in the same group, and, in a few cases, he found only one representative of the supposed type. It might, therefore, be possible that those small uniform plots were the direct progeny of ears, the grains of which had not been mixed with those from other ears before sowing. Exact records had, of course, been kept of the chosen samples, and the number of ears had been noted in each case. It was, therefore, possible to answer the question and it was found that those plots alone were uniform on which the kernels of one single ear only had been sown. Nilsson concluded that the mixture of two or more ears in a single sowing might be the cause of the lack of uniformity in the progeny. Apparently similar ears might be different in their progeny. Once discovered, this fact was elevated to the rank of a leading principle and tested on as large a scale as possible. The fields were again carefully investigated and every single ear, which showed a distinct divergence from the main type in one character or another, was selected. A thousand samples were chosen, but this time each sample consisted of one ear only. Next year, the result corresponded to the expectation. Uniformity prevailed almost everywhere; only a few lots showed a discrepancy, which might be ascribed to the accidental selection of hybrid ears. It was now clear that the progeny of single ears was, as a rule, pure, whereas that of mixed ears was impure. The single-ear selection or single-ear sowing, which had fallen into discredit in Germany and elsewhere in Europe, was rediscovered. It proved to be the only trustworthy principle of selection. Once isolated, such single-parent races are constant from seed and remain true to their type. No further selection is needed; they have simply to be multiplied and their real value tested. Patrick Shirreff, in his early experiments, Le Couteur, Hays and others had observed the rare occurrence of exceptionally good yielders and the value of their isolation to the agriculturist. The possibility of error in the choice of such striking specimens and the necessity of judging their value by their progeny were also known to these investigators, but they had not the slightest idea of all the possibilities suggested by their principle. Nilsson, who is a botanist as well as an agriculturist, discovered that, besides these exceptionably good yielders, every variety of a cereal consists of hundreds of different types, which find the best conditions for success when grown together, but which, after isolation, prove to be constant. Their preference for mixed growth is so definite, that once isolated, their claims on manure and treatment are found to be much higher than those of the original mixed variety. Moreover, the greatest care is necessary to enable them to retain their purity, and as soon as they are left to themselves they begin to deteriorate through accidental crosses and admixtures and rapidly return to the mixed condition. Reverting now to Darwin's discussion of the variability of cereals, we may conclude that subsequent investigation has proved it to be exactly of the kind which he describes. The only difference is that in reality it reaches a degree, quite unexpected by Darwin and his contemporaries. But it is polymorphic variability in the strictest sense of the word. How the single constituents of a variety originate we do not see. We may assume, and there can hardly be a doubt about the truth of the assumption, that a new character, once produced, will slowly but surely be combined through accidental crosses with a large number of previously existing types, and so will tend to double the number of the constituents of the variety. But whether it first appears suddenly or whether it is only slowly evolved we cannot determine. It would, of course, be impossible to observe either process in such a mixture. Only cultures of pure races, of single-parent races as we have called them, can afford an opportunity for this kind of observation. In the fields of Svalof new and unexpected qualities have recently been seen, from time to time, to appear suddenly. These characters are as distinct as the older ones and appear to be constant from the moment of their origin. Darwin has repeatedly insisted that man does not cause variability. He simply selects the variations given to him by the hand of nature. He may repeat this process in order to accumulate different new characters in the same family, thus producing varieties of a higher order. This process of accumulation would, if continued for a longer time, lead to the augmentation of the slight differences characteristic of varieties into the greater differences characteristic of species and genera. It is in this way that horticultural and agricultural experience contribute to the problem of the conversion of varieties into species, and to the explanation of the admirable adaptations of each organism to its complex conditions of life. In the long run new forms, distinguished from their allies by quite a number of new characters, would, by the extermination of the older intermediates, become distinct species. Thus we see that the theory of the origin of species by means of natural selection is quite independent of the question, how the variations to be selected arise. They may arise slowly, from simple fluctuations, or suddenly, by mutations; in both cases natural selection will take hold of them, will multiply them if they are beneficial, and in the course of time accumulate them, so as to produce that great diversity of organic life, which we so highly admire. Darwin has left the decision of this difficult and obviously subordinate point to his followers. But in his Pangenesis hypothesis he has given us the clue for a close study and ultimate elucidation of the subject under discussion. V. HEREDITY AND VARIATION IN MODERN LIGHTS. By W. Bateson, M.A., F.R.S. Professor of Biology in the University of Cambridge. Darwin's work has the property of greatness in that it may be admired from more aspects than one. For some the perception of the principle of Natural Selection stands out as his most wonderful achievement to which all the rest is subordinate. Others, among whom I would range myself, look up to him rather as the first who plainly distinguished, collected, and comprehensively studied that new class of evidence from which hereafter a true understanding of the process of Evolution may be developed. We each prefer our own standpoint of admiration; but I think that it will be in their wider aspect that his labours will most command the veneration of posterity. A treatise written to advance knowledge may be read in two moods. The reader may keep his mind passive, willing merely to receive the impress of the writer's thought; or he may read with his attention strained and alert, asking at every instant how the new knowledge can be used in a further advance, watching continually for fresh footholds by which to climb higher still. Of Shelley it has been said that he was a poet for poets: so Darwin was a naturalist for naturalists. It is when his writings are used in the critical and more exacting spirit with which we test the outfit for our own enterprise that we learn their full value and strength. Whether we glance back and compare his performance with the efforts of his predecessors, or look forward along the course which modern research is disclosing, we shall honour most in him not the rounded merit of finite accomplishment, but the creative power by which he inaugurated a line of discovery endless in variety and extension. Let us attempt thus to see his work in true perspective between the past from which it grew, and the present which is its consequence. Darwin attacked the problem of Evolution by reference to facts of three classes: Variation; Heredity; Natural Selection. His work was not as the laity suppose, a sudden and unheralded revelation, but the first fruit of a long and hitherto barren controversy. The occurrence of variation from type, and the hereditary transmission of such variation had of course been long familiar to practical men, and inferences as to the possible bearing of those phenomena on the nature of specific difference had been from time to time drawn by naturalists. Maupertuis, for example, wrote "Ce qui nous reste a examiner, c'est comment d'un seul individu, il a pu naitre tant d'especes si differentes." And again "La Nature contient le fonds de toutes ces varietes: mais le hasard ou l'art les mettent en oeuvre. C'est ainsi que ceux dont l'industrie s'applique a satisfaire le gout des curieux, sont, pour ainsi dire, creatures d'especes nouvelles." ("Venus Physique, contenant deux Dissertations, l'une sur l'origine des Hommes et des Animaux: Et l'autre sur l'origine des Noirs" La Haye, 1746, pages 124 and 129. For an introduction to the writings of Maupertuis I am indebted to an article by Professor Lovejoy in "Popular Sci. Monthly", 1902.) Such passages, of which many (though few so emphatic) can be found in eighteenth century writers, indicate a true perception of the mode of Evolution. The speculations hinted at by Buffon (For the fullest account of the views of these pioneers of Evolution, see the works of Samuel Butler, especially "Evolution, Old and New" (2nd edition) 1882. Butler's claims on behalf of Buffon have met with some acceptance; but after reading what Butler has said, and a considerable part of Buffon's own works, the word "hinted" seems to me a sufficiently correct description of the part he played. It is interesting to note that in the chapter on the Ass, which contains some of his evolutionary passages, there is a reference to "plusieurs idees tres-elevees sur la generation" contained in the Letters of Maupertuis.), developed by Erasmus Darwin, and independently proclaimed above all by Lamarck, gave to the doctrine of descent a wide renown. The uniformitarian teaching which Lyell deduced from geological observation had gained acceptance. The facts of geographical distribution (See especially W. Lawrence, "Lectures on Physiology", London, 1823, pages 213 f.) had been shown to be obviously inconsistent with the Mosaic legend. Prichard, and Lawrence, following the example of Blumenbach, had successfully demonstrated that the races of Man could be regarded as different forms of one species, contrary to the opinion up till then received. These treatises all begin, it is true, with a profound obeisance to the sons of Noah, but that performed, they continue on strictly modern lines. The question of the mutability of species was thus prominently raised. Those who rate Lamarck no higher than did Huxley in his contemptuous phrase "buccinator tantum," will scarcely deny that the sound of the trumpet had carried far, or that its note was clear. If then there were few who had already turned to evolution with positive conviction, all scientific men must at least have known that such views had been promulgated; and many must, as Huxley says, have taken up his own position of "critical expectancy." (See the chapter contributed to the "Life and Letters of Charles Darwin" II. page 195. I do not clearly understand the sense in which Darwin wrote (Autobiography, ibid. I. page 87): "It has sometimes been said that the success of the "Origin" proved 'that the subject was in the air,' or 'that men's minds were prepared for it.' I do not think that this is strictly true, for I occasionally sounded not a few naturalists, and never happened to come across a single one who seemed to doubt about the permanence of species." This experience may perhaps have been an accident due to Darwin's isolation. The literature of the period abounds with indications of "critical expectancy." A most interesting expression of that feeling is given in the charming account of the "Early Days of Darwinism" by Alfred Newton, "Macmillan's Magazine", LVII. 1888, page 241. He tells how in 1858 when spending a dreary summer in Iceland, he and his friend, the ornithologist John Wolley, in default of active occupation, spent their days in discussion. "Both of us taking a keen interest in Natural History, it was but reasonable that a question, which in those days was always coming up wherever two or more naturalists were gathered together, should be continually recurring. That question was, 'What is a species?' and connected therewith was the other question, 'How did a species begin?'... Now we were of course fairly well acquainted with what had been published on these subjects." He then enumerates some of these publications, mentioning among others T. Vernon Wollaston's "Variation of Species"--a work which has in my opinion never been adequately appreciated. He proceeds: "Of course we never arrived at anything like a solution of these problems, general or special, but we felt very strongly that a solution ought to be found, and that quickly, if the study of Botany and Zoology was to make any great advance." He then describes how on his return home he received the famous number of the "Linnean Journal" on a certain evening. "I sat up late that night to read it; and never shall I forget the impression it made upon me. Herein was contained a perfectly simple solution of all the difficulties which had been troubling me for months past... I went to bed satisfied that a solution had been found.") Why, then, was it, that Darwin succeeded where the rest had failed? The cause of that success was two-fold. First, and obviously, in the principle of Natural Selection he had a suggestion which would work. It might not go the whole way, but it was true as far as it went. Evolution could thus in great measure be fairly represented as a consequence of demonstrable processes. Darwin seldom endangers the mechanism he devised by putting on it strains much greater than it can bear. He at least was under no illusion as to the omnipotence of Selection; and he introduces none of the forced pleading which in recent years has threatened to discredit that principle. For example, in the latest text of the "Origin" ("Origin", (6th edition (1882), page 421.)) we find him saying: "But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position--namely, at the close of the Introduction--the following words: 'I am convinced that natural selection has been the main but not the exclusive means of modification.'" But apart from the invention of this reasonable hypothesis, which may well, as Huxley estimated, "be the guide of biological and psychological speculation for the next three or four generations," Darwin made a more significant and imperishable contribution. Not for a few generations, but through all ages he should be remembered as the first who showed clearly that the problems of Heredity and Variation are soluble by observation, and laid down the course by which we must proceed to their solution. (Whatever be our estimate of the importance of Natural Selection, in this we all agree. Samuel Butler, the most brilliant, and by far the most interesting of Darwin's opponents--whose works are at length emerging from oblivion--in his Preface (1882) to the 2nd edition of "Evolution, Old and New", repeats his earlier expression of homage to one whom he had come to regard as an enemy: "To the end of time, if the question be asked, 'Who taught people to believe in Evolution?' the answer must be that it was Mr. Darwin. This is true, and it is hard to see what palm of higher praise can be awarded to any philosopher.") The moment of inspiration did not come with the reading of Malthus, but with the opening of the "first note-book on Transmutation of Species." ("Life and Letters", I. pages 276 and 83.) Evolution is a process of Variation and Heredity. The older writers, though they had some vague idea that it must be so, did not study Variation and Heredity. Darwin did, and so begat not a theory, but a science. The extent to which this is true, the scientific world is only beginning to realise. So little was the fact appreciated in Darwin's own time that the success of his writings was followed by an almost total cessation of work in that special field. Of the causes which led to this remarkable consequence I have spoken elsewhere. They proceeded from circumstances peculiar to the time; but whatever the causes there is no doubt that this statement of the result is historically exact, and those who make it their business to collect facts elucidating the physiology of Heredity and Variation are well aware that they will find little to reward their quest in the leading scientific Journals of the Darwinian epoch. In those thirty years the original stock of evidence current and in circulation even underwent a process of attrition. As in the story of the Eastern sage who first wrote the collected learning of the universe for his sons in a thousand volumes, and by successive compression and burning reduced them to one, and from this by further burning distilled the single ejaculation of the Faith, "There is no god but God and Mohamed is the Prophet of God," which was all his maturer wisdom deemed essential:--so in the books of that period do we find the corpus of genetic knowledge dwindle to a few prerogative instances, and these at last to the brief formula of an unquestioned creed. And yet in all else that concerns biological science this period was, in very truth, our Golden Age, when the natural history of the earth was explored as never before; morphology and embryology were exhaustively ransacked; the physiology of plants and animals began to rival chemistry and physics in precision of method and in the rapidity of its advances; and the foundations of pathology were laid. In contrast with this immense activity elsewhere the neglect which befel the special physiology of Descent, or Genetics as we now call it, is astonishing. This may of course be interpreted as meaning that the favoured studies seemed to promise a quicker return for effort, but it would be more true to say that those who chose these other pursuits did so without making any such comparison; for the idea that the physiology of Heredity and Variation was a coherent science, offering possibilities of extraordinary discovery, was not present to their minds at all. In a word, the existence of such a science was well nigh forgotten. It is true that in ancillary periodicals, as for example those that treat of entomology or horticulture, or in the writings of the already isolated systematists (This isolation of the systematists is the one most melancholy sequela of Darwinism. It seems an irony that we should read in the peroration to the "Origin" that when the Darwinian view is accepted "Systematists will be able to pursue their labours as at present; but they will not be incessantly haunted by the shadowy doubt whether this or that form be a true species. This, I feel sure, and I speak after experience, will be no slight relief. The endless disputes whether or not some fifty species of British brambles are good species will cease." "Origin", 6th edition (1882), page 425. True they have ceased to attract the attention of those who lead opinion, but anyone who will turn to the literature of systematics will find that they have not ceased in any other sense. Should there not be something disquieting in the fact that among the workers who come most into contact with specific differences, are to be found the only men who have failed to be persuaded of the unreality of those differences?), observations with this special bearing were from time to time related, but the class of fact on which Darwin built his conceptions of Heredity and Variation was not seen in the highways of biology. It formed no part of the official curriculum of biological students, and found no place among the subjects which their teachers were investigating. During this period nevertheless one distinct advance was made, that with which Weismann's name is prominently connected. In Darwin's genetic scheme the hereditary transmission of parental experience and its consequences played a considerable role. Exactly how great that role was supposed to be, he with his habitual caution refrained from specifying, for the sufficient reason that he did not know. Nevertheless much of the process of Evolution, especially that by which organs have become degenerate and rudimentary, was certainly attributed by Darwin to such inheritance, though since belief in the inheritance of acquired characters fell into disrepute, the fact has been a good deal overlooked. The "Origin" without "use and disuse" would be a materially different book. A certain vacillation is discernible in Darwin's utterances on this question, and the fact gave to the astute Butler an opportunity for his most telling attack. The discussion which best illustrates the genetic views of the period arose in regard to the production of the rudimentary condition of the wings of many beetles in the Madeira group of islands, and by comparing passages from the "Origin" (6th edition pages 109 and 401. See Butler, "Essays on Life, Art, and Science", page 265, reprinted 1908, and "Evolution, Old and New", chapter XXII. (2nd edition), 1882.) Butler convicts Darwin of saying first that this condition was in the main the result of Selection, with disuse aiding, and in another place that the main cause of degeneration was disuse, but that Selection had aided. To Darwin however I think the point would have seemed one of dialectics merely. To him the one paramount purpose was to show that somehow an Evolution by means of Variation and Heredity might have brought about the facts observed, and whether they had come to pass in the one way or the other was a matter of subordinate concern. To us moderns the question at issue has a diminished significance. For over all such debates a change has been brought by Weismann's challenge for evidence that use and disuse have any transmitted effects at all. Hitherto the transmission of many acquired characteristics had seemed to most naturalists so obvious as not to call for demonstration. (W. Lawrence was one of the few who consistently maintained the contrary opinion. Prichard, who previously had expressed himself in the same sense, does not, I believe repeat these views in his later writings, and there are signs that he came to believe in the transmission of acquired habits. See Lawrence, "Lect. Physiol." 1823, pages 436-437, 447 Prichard, Edin. Inaug. Disp. 1808 (not seen by me), quoted ibid. and "Nat. Hist. Man", 1843, pages 34 f.) Weismann's demand for facts in support of the main proposition revealed at once that none having real cogency could be produced. The time-honoured examples were easily shown to be capable of different explanations. A few certainly remain which cannot be so summarily dismissed, but--though it is manifestly impossible here to do justice to such a subject--I think no one will dispute that these residual and doubtful phenomena, whatever be their true nature, are not of a kind to help us much in the interpretation of any of those complex cases of adaptation which on the hypothesis of unguided Natural Selection are especially difficult to understand. Use and disuse were invoked expressly to help us over these hard places; but whatever changes can be induced in offspring by direct treatment of the parents, they are not of a kind to encourage hope of real assistance from that quarter. It is not to be denied that through the collapse of this second line of argument the Selection hypothesis has had to take an increased and perilous burden. Various ways of meeting the difficulty have been proposed, but these mostly resolve themselves into improbable attempts to expand or magnify the powers of Natural Selection. Weismann's interpellation, though negative in purpose, has had a lasting and beneficial effect, for through his thorough demolition of the old loose and distracting notions of inherited experience, the ground has been cleared for the construction of a true knowledge of heredity based on experimental fact. In another way he made a contribution of a more positive character, for his elaborate speculations as to the genetic meaning of cytological appearances have led to a minute investigation of the visible phenomena occurring in those divisions by which germ-cells arise. Though the particular views he advocated have very largely proved incompatible with the observed facts of heredity, yet we must acknowledge that it was chiefly through the stimulus of Weismann's ideas that those advances in cytology were made; and though the doctrine of the continuity of germ-plasm cannot be maintained in the form originally propounded, it is in the main true and illuminating. (It is interesting to see how nearly Butler was led by natural penetration, and from absolutely opposite conclusions, back to this underlying truth: "So that each ovum when impregnate should be considered not as descended from its ancestors, but as being a continuation of the personality of every ovum in the chain of its ancestry, which every ovum IT ACTUALLY IS quite as truly as the octogenarian IS the same identity with the ovum from which he has been developed. This process cannot stop short of the primordial cell, which again will probably turn out to be but a brief resting-place. We therefore prove each one of us to BE ACTUALLY the primordial cell which never died nor dies, but has differentiated itself into the life of the world, all living beings whatever, being one with it and members one of another," "Life and Habit", 1878, page 86.) Nevertheless in the present state of knowledge we are still as a rule quite unable to connect cytological appearances with any genetic consequence and save in one respect (obviously of extreme importance--to be spoken of later) the two sets of phenomena might, for all we can see, be entirely distinct. I cannot avoid attaching importance to this want of connection between the nuclear phenomena and the features of bodily organisation. All attempts to investigate Heredity by cytological means lie under the disadvantage that it is the nuclear changes which can alone be effectively observed. Important as they must surely be, I have never been persuaded that the rest of the cell counts for nothing. What we know of the behaviour and variability of chromosomes seems in my opinion quite incompatible with the belief that they alone govern form, and are the sole agents responsible in heredity. (This view is no doubt contrary to the received opinion. I am however interested to see it lately maintained by Driesch ("Science and Philosophy of the Organism", London, 1907, page 233), and from the recent observations of Godlewski it has received distinct experimental support.) If, then, progress was to be made in Genetics, work of a different kind was required. To learn the laws of Heredity and Variation there is no other way than that which Darwin himself followed, the direct examination of the phenomena. A beginning could be made by collecting fortuitous observations of this class, which have often thrown a suggestive light, but such evidence can be at best but superficial and some more penetrating instrument of research is required. This can only be provided by actual experiments in breeding. The truth of these general considerations was becoming gradually clear to many of us when in 1900 Mendel's work was rediscovered. Segregation, a phenomenon of the utmost novelty, was thus revealed. From that moment not only in the problem of the origin of species, but in all the great problems of biology a new era began. So unexpected was the discovery that many naturalists were convinced it was untrue, and at once proclaimed Mendel's conclusions as either altogether mistaken, or if true, of very limited application. Many fantastic notions about the workings of Heredity had been asserted as general principles before: this was probably only another fancy of the same class. Nevertheless those who had a preliminary acquaintance with the facts of Variation were not wholly unprepared for some such revelation. The essential deduction from the discovery of segregation was that the characters of living things are dependent on the presence of definite elements or factors, which are treated as units in the processes of Heredity. These factors can thus be recombined in various ways. They act sometimes separately, and sometimes they interact in conjunction with each other, producing their various effects. All this indicates a definiteness and specific order in heredity, and therefore in variation. This order cannot by the nature of the case be dependent on Natural Selection for its existence, but must be a consequence of the fundamental chemical and physical nature of living things. The study of Variation had from the first shown that an orderliness of this kind was present. The bodies and the properties of living things are cosmic, not chaotic. No matter how low in the scale we go, never do we find the slightest hint of a diminution in that all-pervading orderliness, nor can we conceive an organism existing for a moment in any other state. Moreover not only does this order prevail in normal forms, but again and again it is to be seen in newly-sprung varieties, which by general consent cannot have been subjected to a prolonged Selection. The discovery of Mendelian elements admirably coincided with and at once gave a rationale of these facts. Genetic Variation is then primarily the consequence of additions to, or omissions from, the stock of elements which the species contains. The further investigation of the species-problem must thus proceed by the analytical method which breeding experiments provide. In the nine years which have elapsed since Mendel's clue became generally known, progress has been rapid. We now understand the process by which a polymorphic race maintains its polymorphism. When a family consists of dissimilar members, given the numerical proportions in which these members are occurring, we can represent their composition symbolically and state what types can be transmitted by the various members. The difficulty of the "swamping effects of intercrossing" is practically at an end. Even the famous puzzle of sex-limited inheritance is solved, at all events in its more regular manifestations, and we know now how it is brought about that the normal sisters of a colour-blind man can transmit the colour-blindness while his normal brothers cannot transmit it. We are still only on the fringe of the inquiry. It can be seen extending and ramifying in many directions. To enumerate these here would be impossible. A whole new range of possibilities is being brought into view by study of the interrelations between the simple factors. By following up the evidence as to segregation, indications have been obtained which can only be interpreted as meaning that when many factors are being simultaneously redistributed among the germ-cells, certain of them exert what must be described as a repulsion upon other factors. We cannot surmise whither this discovery may lead. In the new light all the old problems wear a fresh aspect. Upon the question of the nature of Sex, for example, the bearing of Mendelian evidence is close. Elsewhere I have shown that from several sets of parallel experiments the conclusion is almost forced upon us that, in the types investigated, of the two sexes the female is to be regarded as heterozygous in sex, containing one unpaired dominant element, while the male is similarly homozygous in the absence of that element. (In other words, the ova are each EITHER female, OR male (i.e. non-female), but the sperms are all non-female.) It is not a little remarkable that on this point--which is the only one where observations of the nuclear processes of gameto-genesis have yet been brought into relation with the visible characteristics of the organisms themselves--there should be diametrical opposition between the results of breeding experiments and those derived from cytology. Those who have followed the researches of the American school will be aware that, after it had been found in certain insects that the spermatozoa were of two kinds according as they contained or did not contain the accessory chromosome, E.B. Wilson succeeded in proving that the sperms possessing this accessory body were destined to form FEMALES on fertilisation, while sperms without it form males, the eggs being apparently indifferent. Perhaps the most striking of all this series of observations is that lately made by T.H. Morgan (Morgan, "Proc. Soc. Exp. Biol. Med." V. 1908, and von Baehr, "Zool. Anz." XXXII. page 507, 1908.), since confirmed by von Baehr, that in a Phylloxeran two kinds of spermatids are formed, respectively with and without an accessory (in this case, DOUBLE) chromosome. Of these, only those possessing the accessory body become functional spermatozoa, the others degenerating. We have thus an elucidation of the puzzling fact that in these forms fertilisation results in the formation of FEMALES only. How the males are formed--for of course males are eventually produced by the parthenogenetic females--we do not know. If the accessory body is really to be regarded as bearing the factor for femaleness, then in Mendelian terms female is DD and male is DR. The eggs are indifferent and the spermatozoa are each male, OR female. But according to the evidence derived from a study of the sex-limited descent of certain features in other animals the conclusion seems equally clear that in them female must be regarded as DR and male as RR. The eggs are thus each either male or female and the spermatozoa are indifferent. How this contradictory evidence is to be reconciled we do not yet know. The breeding work concerns fowls, canaries, and the Currant moth (Abraxas grossulariata). The accessory chromosome has been now observed in most of the great divisions of insects (As Wilson has proved, the unpaired body is not a universal feature even in those orders in which it has been observed. Nearly allied types may differ. In some it is altogether unpaired. In others it is paired with a body of much smaller size, and by selection of various types all gradations can be demonstrated ranging to the condition in which the members of the pair are indistinguishable from each other.), except, as it happens, Lepidoptera. At first sight it seems difficult to suppose that a feature apparently so fundamental as sex should be differently constituted in different animals, but that seems at present the least improbable inference. I mention these two groups of facts as illustrating the nature and methods of modern genetic work. We must proceed by minute and specific analytical investigation. Wherever we look we find traces of the operation of precise and specific rules. In the light of present knowledge it is evident that before we can attack the Species-problem with any hope of success there are vast arrears to be made up. He would be a bold man who would now assert that there was no sense in which the term Species might not have a strict and concrete meaning in contradistinction to the term Variety. We have been taught to regard the difference between species and variety as one of degree. I think it unlikely that this conclusion will bear the test of further research. To Darwin the question, What is a variation? presented no difficulties. Any difference between parent and offspring was a variation. Now we have to be more precise. First we must, as de Vries has shown, distinguish real, genetic, variation from FLUCTUATIONAL variations, due to environmental and other accidents, which cannot be transmitted. Having excluded these sources of error the variations observed must be expressed in terms of the factors to which they are due before their significance can be understood. For example, numbers of the variations seen under domestication, and not a few witnessed in nature, are simply the consequence of some ingredient being in an unknown way omitted from the composition of the varying individual. The variation may on the contrary be due to the addition of some new element, but to prove that it is so is by no means an easy matter. Casual observation is useless, for though these latter variations will always be dominants, yet many dominant characteristics may arise from another cause, namely the meeting of complementary factors, and special study of each case in two generations at least is needed before these two phenomena can be distinguished. When such considerations are fully appreciated it will be realised that medleys of most dissimilar occurrences are all confused together under the term Variation. One of the first objects of genetic analysis is to disentangle this mass of confusion. To those who have made no study of heredity it sometimes appears that the question of the effect of conditions in causing variation is one which we should immediately investigate, but a little thought will show that before any critical inquiry into such possibilities can be attempted, a knowledge of the working of heredity under conditions as far as possible uniform must be obtained. At the time when Darwin was writing, if a plant brought into cultivation gave off an albino variety, such an event was without hesitation ascribed to the change of life. Now we see that albino GAMETES, germs, that is to say, which are destitute of the pigment-forming factor, may have been originally produced by individuals standing an indefinite number of generations back in the ancestry of the actual albino, and it is indeed almost certain that the variation to which the appearance of the albino is due cannot have taken place in a generation later than that of the grandparents. It is true that when a new DOMINANT appears we should feel greater confidence that we were witnessing the original variation, but such events are of extreme rarity, and no such case has come under the notice of an experimenter in modern times, as far as I am aware. That they must have appeared is clear enough. Nothing corresponding to the Brown-breasted Game fowl is known wild, yet that colour is a most definite dominant, and at some moment since Gallus bankiva was domesticated, the element on which that special colour depends must have at least once been formed in the germ-cell of a fowl; but we need harder evidence than any which has yet been produced before we can declare that this novelty came through over-feeding, or change of climate, or any other disturbance consequent on domestication. When we reflect on the intricacies of genetic problems as we must now conceive them there come moments when we feel almost thankful that the Mendelian principles were unknown to Darwin. The time called for a bold pronouncement, and he made it, to our lasting profit and delight. With fuller knowledge we pass once more into a period of cautious expectation and reserve. In every arduous enterprise it is pleasanter to look back at difficulties overcome than forward to those which still seem insurmountable, but in the next stage there is nothing to be gained by disguising the fact that the attributes of living things are not what we used to suppose. If they are more complex in the sense that the properties they display are throughout so regular (I have in view, for example, the marvellous and specific phenomena of regeneration, and those discovered by the students of "Entwicklungsmechanik". The circumstances of its occurrence here preclude any suggestion that this regularity has been brought about by the workings of Selection. The attempts thus to represent the phenomena have resulted in mere parodies of scientific reasoning.) that the Selection of minute random variations is an unacceptable account of the origin of their diversity, yet by virtue of that very regularity the problem is limited in scope and thus simplified. To begin with, we must relegate Selection to its proper place. Selection permits the viable to continue and decides that the non-viable shall perish; just as the temperature of our atmosphere decides that no liquid carbon shall be found on the face of the earth: but we do not suppose that the form of the diamond has been gradually achieved by a process of Selection. So again, as the course of descent branches in the successive generations, Selection determines along which branch Evolution shall proceed, but it does not decide what novelties that branch shall bring forth. "La Nature contient le fonds de toutes ces varietes, mais le hazard ou l'art les mettent en oeuvre," as Maupertuis most truly said. Not till knowledge of the genetic properties of organisms has attained to far greater completeness can evolutionary speculations have more than a suggestive value. By genetic experiment, cytology and physiological chemistry aiding, we may hope to acquire such knowledge. In 1872 Nathusius wrote ("Vortrage uber Viehzucht und Rassenerkenntniss", page 120, Berlin, 1872.): "Das Gesetz der Vererbung ist noch nicht erkannt; der Apfel ist noch nicht vom Baum der Erkenntniss gefallen, welcher, der Sage nach, Newton auf den rechten Weg zur Ergrundung der Gravitationsgesetze fuhrte." We cannot pretend that the words are not still true, but in Mendelian analysis the seeds of that apple-tree at last are sown. If we were asked what discovery would do most to forward our inquiry, what one bit of knowledge would more than any other illuminate the problem, I think we may give the answer without hesitation. The greatest advance that we can foresee will be made when it is found possible to connect the geometrical phenomena of development with the chemical. The geometrical symmetry of living things is the key to a knowledge of their regularity, and the forces which cause it. In the symmetry of the dividing cell the basis of that resemblance we call Heredity is contained. To imitate the morphological phenomena of life we have to devise a system which can divide. It must be able to divide, and to segment as--grossly--a vibrating plate or rod does, or as an icicle can do as it becomes ribbed in a continuous stream of water; but with this distinction, that the distribution of chemical differences and properties must simultaneously be decided and disposed in orderly relation to the pattern of the segmentation. Even if a model which would do this could be constructed it might prove to be a useful beginning. This may be looking too far ahead. If we had to choose some one piece of more proximate knowledge which we would more especially like to acquire, I suppose we should ask for the secret of interracial sterility. Nothing has yet been discovered to remove the grave difficulty, by which Huxley in particular was so much oppressed, that among the many varieties produced under domestication--which we all regard as analogous to the species seen in nature--no clear case of interracial sterility has been demonstrated. The phenomenon is probably the only one to which the domesticated products seem to afford no parallel. No solution of the difficulty can be offered which has positive value, but it is perhaps worth considering the facts in the light of modern ideas. It should be observed that we are not discussing incompatibility of two species to produce offspring (a totally distinct phenomenon), but the sterility of the offspring which many of them do produce. When two species, both perfectly fertile severally, produce on crossing a sterile progeny, there is a presumption that the sterility is due to the development in the hybrid of some substance which can only be formed by the meeting of two complementary factors. That some such account is correct in essence may be inferred from the well-known observation that if the hybrid is not totally sterile but only partially so, and thus is able to form some good germ-cells which develop into new individuals, the sterility of these daughter-individuals is sensibly reduced or may be entirely absent. The fertility once re-established, the sterility does not return in the later progeny, a fact strongly suggestive of segregation. Now if the sterility of the cross-bred be really the consequence of the meeting of two complementary factors, we see that the phenomenon could only be produced among the divergent offspring of one species by the acquisition of at least TWO new factors; for if the acquisition of a single factor caused sterility the line would then end. Moreover each factor must be separately acquired by distinct individuals, for if both were present together, the possessors would by hypothesis be sterile. And in order to imitate the case of species each of these factors must be acquired by distinct breeds. The factors need not, and probably would not, produce any other perceptible effects; they might, like the colour-factors present in white flowers, make no difference in the form or other characters. Not till the cross was actually made between the two complementary individuals would either factor come into play, and the effects even then might be unobserved until an attempt was made to breed from the cross-bred. Next, if the factors responsible for sterility were acquired, they would in all probability be peculiar to certain individuals and would not readily be distributed to the whole breed. Any member of the breed also into which BOTH the factors were introduced would drop out of the pedigree by virtue of its sterility. Hence the evidence that the various domesticated breeds say of dogs or fowls can when mated together produce fertile offspring, is beside the mark. The real question is, Do they ever produce sterile offspring? I think the evidence is clearly that sometimes they do, oftener perhaps than is commonly supposed. These suggestions are quite amenable to experimental tests. The most obvious way to begin is to get a pair of parents which are known to have had any sterile offspring, and to find the proportions in which these steriles were produced. If, as I anticipate, these proportions are found to be definite, the rest is simple. In passing, certain other considerations may be referred to. First, that there are observations favouring the view that the production of totally sterile cross-breds is seldom a universal property of two species, and that it may be a matter of individuals, which is just what on the view here proposed would be expected. Moreover, as we all know now, though incompatibility may be dependent to some extent on the degree to which the species are dissimilar, no such principle can be demonstrated to determine sterility or fertility in general. For example, though all our Finches can breed together, the hybrids are all sterile. Of Ducks some species can breed together without producing the slightest sterility; others have totally sterile offspring, and so on. The hybrids between several genera of Orchids are perfectly fertile on the female side, and some on the male side also, but the hybrids produced between the Turnip (Brassica napus) and the Swede (Brassica campestris), which, according to our estimates of affinity should be nearly allied forms, are totally sterile. (See Sutton, A.W., "Journ. Linn. Soc." XXXVIII. page 341, 1908.) Lastly, it may be recalled that in sterility we are almost certainly considering a meristic phenomenon. FAILURE TO DIVIDE is, we may feel fairly sure, the immediate "cause" of the sterility. Now, though we know very little about the heredity of meristic differences, all that we do know points to the conclusion that the less-divided is dominant to the more-divided, and we are thus justified in supposing that there are factors which can arrest or prevent cell-division. My conjecture therefore is that in the case of sterility of cross-breds we see the effect produced by a complementary pair of such factors. This and many similar problems are now open to our analysis. The question is sometimes asked, Do the new lights on Variation and Heredity make the process of Evolution easier to understand? On the whole the answer may be given that they do. There is some appearance of loss of simplicity, but the gain is real. As was said above, the time is not ripe for the discussion of the origin of species. With faith in Evolution unshaken--if indeed the word faith can be used in application to that which is certain--we look on the manner and causation of adapted differentiation as still wholly mysterious. As Samuel Butler so truly said: "To me it seems that the 'Origin of Variation,' whatever it is, is the only true 'Origin of Species'" ("Life and Habit", London, page 263, 1878.), and of that Origin not one of us knows anything. But given Variation--and it is given: assuming further that the variations are not guided into paths of adaptation--and both to the Darwinian and to the modern school this hypothesis appears to be sound if unproven--an evolution of species proceeding by definite steps is more, rather than less, easy to imagine than an evolution proceeding by the accumulation of indefinite and insensible steps. Those who have lost themselves in contemplating the miracles of Adaptation (whether real or spurious) have not unnaturally fixed their hopes rather on the indefinite than on the definite changes. The reasons are obvious. By suggesting that the steps through which an adaptative mechanism arose were indefinite and insensible, all further trouble is spared. While it could be said that species arise by an insensible and imperceptible process of variation, there was clearly no use in tiring ourselves by trying to perceive that process. This labour-saving counsel found great favour. All that had to be done to develop evolution-theory was to discover the good in everything, a task which, in the complete absence of any control or test whereby to check the truth of the discovery, is not very onerous. The doctrine "que tout est au mieux" was therefore preached with fresh vigour, and examples of that illuminating principle were discovered with a facility that Pangloss himself might have envied, till at last even the spectators wearied of such dazzling performances. But in all seriousness, why should indefinite and unlimited variation have been regarded as a more probable account of the origin of Adaptation? Only, I think, because the obstacle was shifted one plane back, and so looked rather less prominent. The abundance of Adaptation, we all grant, is an immense, almost an unsurpassable difficulty in all non-Lamarckian views of Evolution; but if the steps by which that adaptation arose were fortuitous, to imagine them insensible is assuredly no help. In one most important respect indeed, as has often been observed, it is a multiplication of troubles. For the smaller the steps, the less could Natural Selection act upon them. Definite variations--and of the occurrence of definite variations in abundance we have now the most convincing proof--have at least the obvious merit that they can make and often do make a real difference in the chances of life. There is another aspect of the Adaptation problem to which I can only allude very briefly. May not our present ideas of the universality and precision of Adaptation be greatly exaggerated? The fit of organism to its environment is not after all so very close--a proposition unwelcome perhaps, but one which could be illustrated by very copious evidence. Natural Selection is stern, but she has her tolerant moods. We have now most certain and irrefragable proof that much definiteness exists in living things apart from Selection, and also much that may very well have been preserved and so in a sense constituted by Selection. Here the matter is likely to rest. There is a passage in the sixth edition of the "Origin" which has I think been overlooked. On page 70 Darwin says "The tuft of hair on the breast of the wild turkey-cock cannot be of any use, and it is doubtful whether it can be ornamental in the eyes of the female bird." This tuft of hair is a most definite and unusual structure, and I am afraid that the remark that it "cannot be of any use" may have been made inadvertently; but it may have been intended, for in the first edition the usual qualification was given and must therefore have been deliberately excised. Anyhow I should like to think that Darwin did throw over that tuft of hair, and that he felt relief when he had done so. Whether however we have his great authority for such a course or not, I feel quite sure that we shall be rightly interpreting the facts of nature if we cease to expect to find purposefulness wherever we meet with definite structures or patterns. Such things are, as often as not, I suspect rather of the nature of tool-marks, mere incidents of manufacture, benefiting their possessor not more than the wire-marks in a sheet of paper, or the ribbing on the bottom of an oriental plate renders those objects more attractive in our eyes. If Variation may be in any way definite, the question once more arises, may it not be definite in direction? The belief that it is has had many supporters, from Lamarck onwards, who held that it was guided by need, and others who, like Nageli, while laying no emphasis on need, yet were convinced that there was guidance of some kind. The latter view under the name of "Orthogenesis," devised I believe by Eimer, at the present day commends itself to some naturalists. The objection to such a suggestion is of course that no fragment of real evidence can be produced in its support. On the other hand, with the experimental proof that variation consists largely in the unpacking and repacking of an original complexity, it is not so certain as we might like to think that the order of these events is not pre-determined. For instance the original "pack" may have been made in such a way that at the nth division of the germ-cells of a Sweet Pea a colour-factor might be dropped, and that at the n plus n prime division the hooded variety be given off, and so on. I see no ground whatever for holding such a view, but in fairness the possibility should not be forgotten, and in the light of modern research it scarcely looks so absurdly improbable as before. No one can survey the work of recent years without perceiving that evolutionary orthodoxy developed too fast, and that a great deal has got to come down; but this satisfaction at least remains, that in the experimental methods which Mendel inaugurated, we have means of reaching certainty in regard to the physiology of Heredity and Variation upon which a more lasting structure may be built. VI. THE MINUTE STRUCTURE OF CELLS IN RELATION TO HEREDITY. By Eduard Strasburger. Professor of Botany in the University of Bonn. Since 1875 an unexpected insight has been gained into the internal structure of cells. Those who are familiar with the results of investigations in this branch of Science are convinced that any modern theory of heredity must rest on a basis of cytology and cannot be at variance with cytological facts. Many histological discoveries, both such as have been proved correct and others which may be accepted as probably well founded, have acquired a fundamental importance from the point of view of the problems of heredity. My aim is to describe the present position of our knowledge of Cytology. The account must be confined to essentials and cannot deal with far-reaching and controversial questions. In cases where difference of opinion exists, I adopt my own view for which I hold myself responsible. I hope to succeed in making myself intelligible even without the aid of illustrations: in order to convey to the uninitiated an adequate idea of the phenomena connected with the life of a cell, a greater number of figures would be required than could be included within the scope of this article. So long as the most eminent investigators (As for example the illustrious Wilhelm Hofmeister in his "Lehre von der Pflanzenzelle" (1867).) believed that the nucleus of a cell was destroyed in the course of each division and that the nuclei of the daughter-cells were produced de novo, theories of heredity were able to dispense with the nucleus. If they sought, as did Charles Darwin, who showed a correct grasp of the problem in the enunciation of his Pangenesis hypothesis, for histological connecting links, their hypotheses, or at least the best of them, had reference to the cell as a whole. It was known to Darwin that the cell multiplied by division and was derived from a similar pre-existing cell. Towards 1870 it was first demonstrated that cell-nuclei do not arise de novo, but are invariably the result of division of pre-existing nuclei. Better methods of investigation rendered possible a deeper insight into the phenomena accompanying cell and nuclear divisions and at the same time disclosed the existence of remarkable structures. The work of O. Butschli, O. Hertwig, W. Flemming H. Fol and of the author of this article (For further reference to literature, see my article on "Die Ontogenie der Zelle seit 1875", in the "Progressus Rei Botanicae", Vol. I. page 1, Jena, 1907.), have furnished conclusive evidence in favour of these facts. It was found that when the reticular framework of a nucleus prepares to divide, it separates into single segments. These then become thicker and denser, taking up with avidity certain stains, which are used as aids to investigation, and finally form longer or shorter, variously bent, rodlets of uniform thickness. In these organs which, on account of their special property of absorbing certain stains, were styled Chromosomes (By W. Waldeyer in 1888.), there may usually be recognised a separation into thicker and thinner discs; the former are often termed Chromomeres. (Discovered by W. Pfitzner in 1880.) In the course of division of the nucleus, the single rows of chromomeres in the chromosomes are doubled and this produces a band-like flattening and leads to the longitudinal splitting by which each chromosome is divided into two exactly equal halves. The nuclear membrane then disappears and fibrillar cell-plasma or cytoplasm invades the nuclear area. In animal cells these fibrillae in the cytoplasm centre on definite bodies (Their existence and their multiplication by fission were demonstrated by E. van Beneden and Th. Boveri in 1887.), which it is customary to speak of as Centrosomes. Radiating lines in the adjacent cell-plasma suggest that these bodies constitute centres of force. The cells of the higher plants do not possess such individualised centres; they have probably disappeared in the course of phylogenetic development: in spite of this, however, in the nuclear division-figures the fibrillae of the cell-plasma are seen to radiate from two opposite poles. In both animal and plant cells a fibrillar bipolar spindle is formed, the fibrillae of which grasp the longitudinally divided chromosomes from two opposite sides and arrange them on the equatorial plane of the spindle as the so-called nuclear or equatorial plate. Each half-chromosome is connected with one of the spindle poles only and is then drawn towards that pole. (These important facts, suspected by W. Flemming in 1882, were demonstrated by E. Heuser, L. Guignard, E. van Beneden, M. Nussbaum, and C. Rabl.) The formation of the daughter-nuclei is then effected. The changes which the daughter-chromosomes undergo in the process of producing the daughter-nuclei repeat in the reverse order the changes which they went through in the course of their progressive differentiation from the mother-nucleus. The division of the cell-body is completed midway between the two daughter-nuclei. In animal cells, which possess no chemically differentiated membrane, separation is effected by simple constriction, while in the case of plant cells provided with a definite wall, the process begins with the formation of a cytoplasmic separating layer. The phenomena observed in the course of the division of the nucleus show beyond doubt that an exact halving of its substance is of the greatest importance. (First shown by W. Roux in 1883.) Compared with the method of division of the nucleus, that of the cytoplasm appears to be very simple. This led to the conception that the cell-nucleus must be the chief if not the sole carrier of hereditary characters in the organism. It is for this reason that the detailed investigation of fertilisation phenomena immediately followed researches into the nucleus. The fundamental discovery of the union of two nuclei in the sexual act was then made (By O. Hertwig in 1875.) and this afforded a new support for the correct conception of the nuclear functions. The minute study of the behaviour of the other constituents of sexual cells during fertilisation led to the result, that the nucleus alone is concerned with handing on hereditary characters (This was done by O. Hertwig and the author of this essay simultaneously in 1884.) from one generation to another. Especially important, from the point of view of this conclusion, is the study of fertilisation in Angiosperms (Flowering plants); in these plants the male sexual cells lose their cell-body in the pollen-tube and the nucleus only--the sperm-nucleus--reaches the egg. The cytoplasm of the male sexual cell is therefore not necessary to ensure a transference of hereditary characters from parents to offspring. I lay stress on the case of the Angiosperms because researches recently repeated with the help of the latest methods failed to obtain different results. As regards the descendants of angiospermous plants, the same laws of heredity hold good as for other sexually differentiated organisms; we may, therefore, extend to the latter what the Angiosperms so clearly teach us. The next advance in the hitherto rapid progress in our knowledge of nuclear division was delayed, because it was not at once recognised that there are two absolutely different methods of nuclear division. All such nuclear divisions were united under the head of indirect or mitotic divisions; these were also spoken of as karyo-kineses, and were distinguished from the direct or amitotic divisions which are characterised by a simple constriction of the nuclear body. So long as the two kinds of indirect nuclear division were not clearly distinguished, their correct interpretation was impossible. This was accomplished after long and laborious research, which has recently been carried out and with results which should, perhaps, be regarded as provisional. Soon after the new study of the nucleus began, investigators were struck by the fact that the course of nuclear division in the mother-cells, or more correctly in the grandmother-cells, of spores, pollen-grains, and embryo-sacs of the more highly organised plants and in the spermatozoids and eggs of the higher animals, exhibits similar phenomena, distinct from those which occur in the somatic cells. In the nuclei of all those cells which we may group together as gonotokonts (At the suggestion of J.P. Lotsy in 1904.) (i.e. cells concerned in reproduction) there are fewer chromosomes than in the adjacent body-cells (somatic cells). It was noticed also that there is a peculiarity characteristic of the gonotokonts, namely the occurrence of two nuclear divisions rapidly succeeding one another. It was afterwards recognised that in the first stage of nuclear division in the gonotokonts the chromosomes unite in pairs: it is these chromosome-pairs, and not the two longitudinal halves of single chromosomes, which form the nuclear plate in the equatorial plane of the nuclear spindle. It has been proposed to call these pairs gemini. (J.E.S. Moore and A.L. Embleton, "Proc. Roy. Soc." London, Vol. LXXVII. page 555, 1906; V. Gregoire, 1907.) In the course of this division the spindle-fibrillae attach themselves to the gemini, i.e. to entire chromosomes and direct them to the points where the new daughter-nuclei are formed, that is to those positions towards which the longitudinal halves of the chromosomes travel in ordinary nuclear divisions. It is clear that in this way the number of chromosomes which the daughter-nuclei contain, as the result of the first stage in division in the gonotokonts, will be reduced by one half, while in ordinary divisions the number of chromosomes always remains the same. The first stage in the division of the nucleus in the gonotokonts has therefore been termed the reduction division. (In 1887 W. Flemming termed this the heterotypic form of nuclear division.) This stage in division determines the conditions for the second division which rapidly ensues. Each of the paired chromosomes of the mother-nucleus has already, as in an ordinary nuclear division, completed the longitudinal fission, but in this case it is not succeeded by the immediate separation of the longitudinal halves and their allotment to different nuclei. Each chromosome, therefore, takes its two longitudinal halves into the same daughter-nucleus. Thus, in each daughter-nucleus the longitudinal halves of the chromosomes are present ready for the next stage in the division; they only require to be arranged in the nuclear plate and then distributed among the granddaughter-nuclei. This method of division, which takes place with chromosomes already split, and which have only to provide for the distribution of their longitudinal halves to the next nuclear generation, has been called homotypic nuclear division. (The name was proposed by W. Flemming in 1887; the nature of this type of division was, however, not explained until later.) Reduction division and homotypic nuclear division are included together under the term allotypic nuclear division and are distinguished from the ordinary or typical nuclear division. The name Meiosis (By J. Bretland Farmer and J.E.S. Moore in 1905.) has also been proposed for these two allotypic nuclear divisions. The typical divisions are often spoken of as somatic. Observers who were actively engaged in this branch of recent histological research soon noticed that the chromosomes of a given organism are differentiated in definite numbers from the nuclear network in the course of division. This is especially striking in the gonotokonts, but it applies also to the somatic tissues. In the latter, one usually finds twice as many chromosomes as in the gonotokonts. Thus the conclusion was gradually reached that the doubling of chromosomes, which necessarily accompanies fertilisation, is maintained in the product of fertilisation, to be again reduced to one half in the gonotokonts at the stage of reduction-division. This enabled us to form a conception as to the essence of true alternation of generations, in which generations containing single and double chromosomes alternate with one another. The single-chromosome generation, which I will call the HAPLOID, must have been the primitive generation in all organisms; it might also persist as the only generation. Every sexual differentiation in organisms, which occurred in the course of phylogenetic development, was followed by fertilisation and therefore by the creation of a diploid or double-chromosome product. So long as the germination of the product of fertilisation, the zygote, began with a reducing process, a special DIPLOID generation was not represented. This, however, appeared later as a product of the further evolution of the zygote, and the reduction division was correspondingly postponed. In animals, as in plants, the diploid generation attained the higher development and gradually assumed the dominant position. The haploid generation suffered a proportional reduction, until it finally ceased to have an independent existence and became restricted to the role of producing the sexual products within the body of the diploid generation. Those who do not possess the necessary special knowledge are unable to realise what remains of the first haploid generation in a phanerogamic plant or in a vertebrate animal. In Angiosperms this is actually represented only by the short developmental stages which extend from the pollen mother-cells to the sperm-nucleus of the pollen-tube, and from the embryo-sac mother-cell to the egg and the endosperm tissue. The embryo-sac remains enclosed in the diploid ovule, and within this from the fertilised egg is formed the embryo which introduces the new diploid generation. On the full development of the diploid embryo of the next generation, the diploid ovule of the preceding diploid generation is separated from the latter as a ripe seed. The uninitiated sees in the more highly organised plants only a succession of diploid generations. Similarly all the higher animals appear to us as independent organisms with diploid nuclei only. The haploid generation is confined in them to the cells produced as the result of the reduction division of the gonotokonts; the development of these is completed with the homotypic stage of division which succeeds the reduction division and produces the sexual products. The constancy of the numbers in which the chromosomes separate themselves from the nuclear network during division gave rise to the conception that, in a certain degree, chromosomes possess individuality. Indeed the most careful investigations (Particularly those of V. Gregoire and his pupils.) have shown that the segments of the nuclear network, which separate from one another and condense so as to produce chromosomes for a new division, correspond to the segments produced from the chromosomes of the preceding division. The behaviour of such nuclei as possess chromosomes of unequal size affords confirmatory evidence of the permanence of individual chromosomes in corresponding sections of an apparently uniform nuclear network. Moreover at each stage in division chromosomes with the same differences in size reappear. Other cases are known in which thicker portions occur in the substance of the resting nucleus, and these agree in number with the chromosomes. In this network, therefore, the individual chromosomes must have retained their original position. But the chromosomes cannot be regarded as the ultimate hereditary units in the nuclei, as their number is too small. Moreover, related species not infrequently show a difference in the number of their chromosomes, whereas the number of hereditary units must approximately agree. We thus picture to ourselves the carriers of hereditary characters as enclosed in the chromosomes; the transmitted fixed number of chromosomes is for us only the visible expression of the conception that the number of hereditary units which the chromosomes carry must be also constant. The ultimate hereditary units may, like the chromosomes themselves, retain a definite position in the resting nucleus. Further, it may be assumed that during the separation of the chromosomes from one another and during their assumption of the rod-like form, the hereditary units become aggregated in the chromomeres and that these are characterised by a constant order of succession. The hereditary units then grow, divide into two and are uniformly distributed by the fission of the chromosomes between their longitudinal halves. As the contraction and rod-like separation of the chromosomes serve to isnure the transmission of all hereditary units in the products of division of a nucleus, so, on the other hand, the reticular distension of each chromosome in the so-called resting nucleus may effect a separation of the carriers of hereditary units from each other and facilitate the specific activity of each of them. In the stages preliminary to their division, the chromosomes become denser and take up a substance which increases their staining capacity; this is called chromatin. This substance collects in the chromomeres and may form the nutritive material for the carriers of hereditary units which we now believe to be enclosed in them. The chromatin cannot itself be the hereditary substance, as it afterwards leaves the chromosomes, and the amount of it is subject to considerable variation in the nucleus, according to its stage of development. Conjointly with the materials which take part in the formation of the nuclear spindle and other processes in the cell, the chromatin accumulates in the resting nucleus to form the nucleoli. Naturally connected with the conclusion that the nuclei are the carriers of hereditary characters in the organism, is the question whether enucleate organisms can also exist. Phylogenetic considerations give an affirmative answer to this question. The differentiation into nucleus and cytoplasm represents a division of labour in the protoplast. A study of organisms which belong to the lowest class of the organic world teaches us how this was accomplished. Instead of well-defined nuclei, scattered granules have been described in the protoplasm of several of these organisms (Bacteria, Cyanophyceae, Protozoa.), characterised by the same reactions as nuclear material, provided also with a nuclear network, but without a limiting membrane. (This is the result of the work of R. Hertwig and of the most recently published investigations.) Thus the carriers of hereditary characters may originally have been distributed in the common protoplasm, afterwards coming together and eventually assuming a definite form as special organs of the cell. It may be also assumed that in the protoplasm and in the primitive types of nucleus, the carriers of the same hereditary unit were represented in considerable quantity; they became gradually differentiated to an extent commensurate with newly acquired characters. It was also necessary that, in proportion as this happened, the mechanism of nuclear division must be refined. At first processes resembling a simple constriction would suffice to provide for the distribution of all hereditary units to each of the products of division, but eventually in both organic kingdoms nuclear division, which alone insured the qualitative identity of the products of division, became a more marked feature in the course of cell-multiplication. Where direct nuclear division occurs by constriction in the higher organisms, it does not result in the halving of hereditary units. So far as my observations go, direct nuclear division occurs in the more highly organised plants only in cells which have lost their specific functions. Such cells are no longer capable of specific reproduction. An interesting case in this connection is afforded by the internodal cells of the Characeae, which possess only vegetative functions. These cells grow vigorously and their cytoplasm increases, their growth being accompanied by a correspondingly direct multiplication of the nuclei. They serve chiefly to nourish the plant, but, unlike the other cells, they are incapable of producing any offspring. This is a very instructive case, because it clearly shows that the nuclei are not only carriers of hereditary characters, but that they also play a definite part in the metabolism of the protoplasts. Attention was drawn to the fact that during the reducing division of nuclei which contain chromosomes of unequal size, gemini are constantly produced by the pairing of chromosomes of the same size. This led to the conclusion that the pairing chromosomes are homologous, and that one comes from the father, the other from the mother. (First stated by T.H. Montgomery in 1901 and by W.S. Sutton in 1902.) This evidently applies also to the pairing of chromosomes in those reduction-divisions in which differences in size do not enable us to distinguish the individual chromosomes. In this case also each pair would be formed by two homologous chromosomes, the one of paternal, the other of maternal origin. When the separation of these chromosomes and their distribution to both daughter-nuclei occur a chromosome of each kind is provided for each of these nuclei. It would seem that the components of each pair might pass to either pole of the nuclear spindle, so that the paternal and maternal chromosomes would be distributed in varying proportion between the daughter-nuclei; and it is not impossible that one daughter-nucleus might occasionally contain paternal chromosomes only and its sister-nucleus exclusively maternal chromosomes. The fact that in nuclei containing chromosomes of various sizes, the chromosomes which pair together in reduction-division are always of equal size, constitutes a further and more important proof of their qualitative difference. This is supported also by ingenious experiments which led to an unequal distribution of chromosomes in the products of division of a sea-urchin's egg, with the result that a difference was induced in their further development. (Demonstrated by Th. Boveri in 1902.) The recently discovered fact that in diploid nuclei the chromosomes are arranged in pairs affords additional evidence in favour of the unequal value of the chromosomes. This is still more striking in the case of chromosomes of different sizes. It has been shown that in the first division-figure in the nucleus of the fertilised egg the chromosomes of corresponding size form pairs. They appear with this arrangement in all subsequent nuclear divisions in the diploid generation. The longitudinal fissions of the chromosomes provide for the unaltered preservation of this condition. In the reduction nucleus of the gonotokonts the homologous chromosomes being near together need not seek out one another; they are ready to form gemini. The next stage is their separation to the haploid daughter-nuclei, which have resulted from the reduction process. Peculiar phenomena in the reduction nucleus accompany the formation of gemini in both organic kingdoms. (This has been shown more particularly by the work of L. Guignard, M. Mottier, J.B. Farmer, C.B. Wilson, V. Hacker and more recently by V. Gregoire and his pupil C.A. Allen, by the researches conducted in the Bonn Botanical Institute, and by A. and K.E. Schreiner.) Probably for the purpose of entering into most intimate relation, the pairs are stretched to long threads in which the chromomeres come to lie opposite one another. (C.A. Allen, A. and K.E. Schreiner, and Strasburger.) It seems probable that these are homologous chromomeres, and that the pairs afterwards unite for a short time, so that an exchange of hereditary units is rendered possible. (H. de Vries and Strasburger.) This cannot be actually seen, but certain facts of heredity point to the conclusion that this occurs. It follows from these phenomena that any exchange which may be effected must be one of homologous carriers of hereditary units only. These units continue to form exchangeable segments after they have undergone unequal changes; they then constitute allelotropic pairs. We may thus calculate what sum of possible combinations the exchange of homologous hereditary units between the pairing chromosomes provides for before the reduction division and the subsequent distribution of paternal and maternal chromosomes in the haploid daughter-nuclei. These nuclei then transmit their characters to the sexual cells, the conjugation of which in fertilization again produces the most varied combinations. (A. Weismann gave the impulse to these ideas in his theory on "Amphimixis".) In this way all the cooperations which the carriers of hereditary characters are capable of in a species are produced; this must give it an appreciable advantage in the struggle for life. The admirers of Charles Darwin must deeply regret that he did not live to see the results achieved by the new Cytology. What service would they have been to him in the presentation of his hypothesis of Pangenesis; what an outlook into the future would they have given to his active mind! The Darwinian hypothesis of Pangenesis rests on the conception that all inheritable properties are represented in the cells by small invisible particles or gemmules and that these gemmules increase by division. Cytology began to develop on new lines some years after the publication in 1868 of Charles Darwin's "Provisional hypothesis of Pangenesis" ("Animals and Plants under Domestication", London, 1868, Chapter XXVII.), and when he died in 1882 it was still in its infancy. Darwin would have soon suggested the substitution of the nuclei for his gemmules. At least the great majority of present-day investigators in the domain of cytology have been led to the conclusion that the nucleus is the carrier of hereditary characters, and they also believe that hereditary characters are represented in the nucleus as distinct units. Such would be Darwin's gemmules, which in conformity with the name of his hypothesis may be called pangens (So called by H. de Vries in 1889.): these pangens multiply by division. All recently adopted views may be thus linked on to this part of Darwin's hypothesis. It is otherwise with Darwin's conception to which Pangenesis owes its name, namely the view that all cells continually give off gemmules, which migrate to other places in the organism, where they unite to form reproductive cells. When Darwin foresaw this possibility, the continuity of the germinal substance was still unknown (Demonstrated by Nussbaum in 1880, by Sachs in 1882, and by Weismann in 1885.), a fact which excludes a transference of gemmules. But even Charles Darwin's genius was confined within finite boundaries by the state of science in his day. It is not my province to deal with other theories of development which followed from Darwin's Pangenesis, or to discuss their histological probabilities. We can, however, affirm that Charles Darwin's idea that invisible gemmules are the carriers of hereditary characters and that they multiply by division has been removed from the position of a provisional hypothesis to that of a well-founded theory. It is supported by histology, and the results of experimental work in heredity, which are now assuming extraordinary prominence, are in close agreement with it. VII. "THE DESCENT OF MAN". By G. Schwalbe. Professor of Anatomy in the University of Strassburg. The problem of the origin of the human race, of the descent of man, is ranked by Huxley in his epoch-making book "Man's Place in Nature", as the deepest with which biology has to concern itself, "the question of questions,"--the problem which underlies all others. In the same brilliant and lucid exposition, which appeared in 1863, soon after the publication of Darwin's "Origin of Species", Huxley stated his own views in regard to this great problem. He tells us how the idea of a natural descent of man gradually grew up in his mind, it was especially the assertions of Owen in regard to the total difference between the human and the simian brain that called forth strong dissent from the great anatomist Huxley, and he easily succeeded in showing that Owen's supposed differences had no real existence; he even established, on the basis of his own anatomical investigations, the proposition that the anatomical differences between the Marmoset and the Chimpanzee are much greater than those between the Chimpanzee and Man. But why do we thus introduce the study of Darwin's "Descent of Man", which is to occupy us here, by insisting on the fact that Huxley had taken the field in defence of the descent of man in 1863, while Darwin's book on the subject did not appear till 1871? It is in order that we may clearly understand how it happened that from this time onwards Darwin and Huxley followed the same great aim in the most intimate association. Huxley and Darwin working at the same Problema maximum! Huxley fiery, impetuous, eager for battle, contemptuous of the resistance of a dull world, or energetically triumphing over it. Darwin calm, weighing every problem slowly, letting it mature thoroughly,--not a fighter, yet having the greater and more lasting influence by virtue of his immense mass of critically sifted proofs. Darwin's friend, Huxley, was the first to do him justice, to understand his nature, and to find in it the reason why the detailed and carefully considered book on the descent of man made its appearance so late. Huxley, always generous, never thought of claiming priority for himself. In enthusiastic language he tells how Darwin's immortal work, "The Origin of Species", first shed light for him on the problem of the descent of man; the recognition of a vera causa in the transformation of species illuminated his thoughts as with a flash. He was now content to leave what perplexed him, what he could not yet solve, as he says himself, "in the mighty hands of Darwin." Happy in the bustle of strife against old and deep-rooted prejudices, against intolerance and superstition, he wielded his sharp weapons on Darwin's behalf; wearing Darwin's armour he joyously overthrew adversary after adversary. Darwin spoke of Huxley as his "general agent." ("Life and Letters of Thomas Henry Huxley", Vol. I. page 171, London, 1900.) Huxley says of himself "I am Darwin's bulldog." (Ibid. page 363.) Thus Huxley openly acknowledged that it was Darwin's "Origin of Species" that first set the problem of the descent of man in its true light, that made the question of the origin of the human race a pressing one. That this was the logical consequence of his book Darwin himself had long felt. He had been reproached with intentionally shirking the application of his theory to Man. Let us hear what he says on this point in his autobiography: "As soon as I had become, in the year 1837 or 1838, convinced that species were mutable productions, I could not avoid the belief that man must come under the same law. Accordingly I collected notes on the subject for my own satisfaction, and not for a long time with any intention of publishing. Although in the 'Origin of Species' the derivation of any particular species is never discussed, yet I thought it best, in order THAT NO HONOURABLE MAN SHOULD ACCUSE ME OF CONCEALING MY VIEWS (No italics in original.), to add that by the work 'light would be thrown on the origin of man and his history.' It would have been useless and injurious to the success of the book to have paraded, without giving any evidence, my conviction with respect to his origin." ("Life and Letters of Charles Darwin", Vol. 1. page 93.) In a letter written in January, 1860, to the Rev. L. Blomefield, Darwin expresses himself in similar terms. "With respect to man, I am very far from wishing to obtrude my belief; but I thought it dishonest to quite conceal my opinion." (Ibid. Vol. II. page 263.) The brief allusion in the "Origin of Species" is so far from prominent and so incidental that it was excusable to assume that Darwin had not touched upon the descent of man in this work. It was solely the desire to have his mass of evidence sufficiently complete, solely Darwin's great characteristic of never publishing till he had carefully weighed all aspects of his subject for years, solely, in short, his most fastidious scientific conscience that restrained him from challenging the world in 1859 with a book in which the theory of the descent of man was fully set forth. Three years, frequently interrupted by ill-health, were needed for the actual writing of the book ("Life and Letters", Vol. I. page 94.): the first edition, which appeared in 1871, was followed in 1874 by a much improved second edition, the preparation of which he very reluctantly undertook. (Ibid. Vol. III. page 175.) This, briefly, is the history of the work, which, with the "Origin of Species", marks an epoch in the history of biological sciences--the work with which the cautious, peace-loving investigator ventured forth from his contemplative life into the arena of strife and unrest, and laid himself open to all the annoyances that deep-rooted belief and prejudice, and the prevailing tendency of scientific thought at the time could devise. Darwin did not take this step lightly. Of great interest in this connection is a letter written to Wallace on Dec. 22, 1857 (Ibid. Vol. II. page 109.), in which he says "You ask whether I shall discuss 'man.' I think I shall avoid the whole subject, as so surrounded with prejudices; though I fully admit that it is the highest and most interesting problem for the naturalist." But his conscientiousness compelled him to state briefly his opinion on the subject in the "Origin of Species" in 1859. Nevertheless he did not escape reproaches for having been so reticent. This is unmistakably apparent from a letter to Fritz Muller dated February 22 (1869?), in which he says: "I am thinking of writing a little essay on the Origin of Mankind, as I have been taunted with concealing my opinions." (Ibid. Vol. III. page 112.) It might be thought that Darwin behaved thus hesitatingly, and was so slow in deciding on the full publication of his collected material in regard to the descent of man, because he had religious difficulties to overcome. But this was not the case, as we can see from his admirable confession of faith, the publication of which we owe to his son Francis. (Ibid. Vol. I. pages 304-317.) Whoever wishes really to understand the lofty character of this great man should read these immortal lines in which he unfolds to us in simple and straightforward words the development of his conception of the universe. He describes how, though he was still quite orthodox during his voyage round the world on board the "Beagle", he came gradually to see, shortly afterwards (1836-1839) that the Old Testament was no more to be trusted than the Sacred Books of the Hindoos; the miracles by which Christianity is supported, the discrepancies between the accounts in the different Gospels, gradually led him to disbelieve in Christianity as a divine revelation. "Thus," he writes ("Life and Letters", Vol. 1. page 309.), "disbelief crept over me at a very slow rate, but was at last complete. The rate was so slow that I felt no distress." But Darwin was too modest to presume to go beyond the limits laid down by science. He wanted nothing more than to be able to go, freely and unhampered by belief in authority or in the Bible, as far as human knowledge could lead him. We learn this from the concluding words of his chapter on religion: "The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an Agnostic." (Loc. cit. page 313.) Darwin was always very unwilling to give publicity to his views in regard to religion. In a letter to Asa Gray on May 22, 1860 (Ibid. Vol. II. page 310.), he declares that it is always painful to him to have to enter into discussion of religious problems. He had, he said, no intention of writing atheistically. Finally, let us cite one characteristic sentence from a letter from Darwin to C. Ridley (Ibid. Vol. III. page. 236. ("C. Ridley," Mr Francis Darwin points out to me, should be H.N. Ridley. A.C.S.)) (Nov. 28, 1878.) A clergyman, Dr Pusey, had asserted that Darwin had written the "Origin of Species" with some relation to theology. Darwin writes emphatically, "Many years ago, when I was collecting facts for the 'Origin', my belief in what is called a personal God was as firm as that of Dr Pusey himself, and as to the eternity of matter I never troubled myself about such insoluble questions." The expression "many years ago" refers to the time of his voyage round the world, as has already been pointed out. Darwin means by this utterance that the views which had gradually developed in his mind in regard to the origin of species were quite compatible with the faith of the Church. If we consider all these utterances of Darwin in regard to religion and to his outlook on life (Weltanschauung), we shall see at least so much, that religious reflection could in no way have influenced him in regard to the writing and publishing of his book on "The Descent of Man". Darwin had early won for himself freedom of thought, and to this freedom he remained true to the end of his life, uninfluenced by the customs and opinions of the world around him. Darwin was thus inwardly fortified and armed against the host of calumnies, accusations, and attacks called forth by the publication of the "Origin of Species", and to an even greater extent by the appearance of the "Descent of Man". But in his defence he could rely on the aid of a band of distinguished auxiliaries of the rarest ability. His faithful confederate, Huxley, was joined by the botanist Hooker, and, after longer resistance, by the famous geologist Lyell, whose "conversion" afforded Darwin peculiar satisfaction. All three took the field with enthusiasm in defence of the natural descent of man. From Wallace, on the other hand, though he shared with him the idea of natural selection, Darwin got no support in this matter. Wallace expressed himself in a strange manner. He admitted everything in regard to the morphological descent of man, but maintained, in a mystic way, that something else, something of a spiritual nature must have been added to what man inherited from his animal ancestors. Darwin, whose esteem for Wallace was extraordinarily high, could not understand how he could give utterance to such a mystical view in regard to man; the idea seemed to him so "incredibly strange" that he thought some one else must have added these sentences to Wallace's paper. Even now there are thinkers who, like Wallace, shrink from applying to man the ultimate consequences of the theory of descent. The idea that man is derived from ape-like forms is to them unpleasant and humiliating. So far I have been depicting the development of Darwin's work on the descent of man. In what follows I shall endeavour to give a condensed survey of the contents of the book. It must at once be said that the contents of Darwin's work fall into two parts, dealing with entirely different subjects. "The Descent of Man" includes a very detailed investigation in regard to secondary sexual characters in the animal series, and on this investigation Darwin founded a new theory, that of sexual selection. With astonishing patience he gathered together an immense mass of material, and showed, in regard to Arthropods and Vertebrates, the wide distribution of secondary characters, which develop almost exclusively in the male, and which enable him, on the one hand, to get the better of his rivals in the struggle for the female by the greater perfection of his weapons, and on the other hand, to offer greater allurements to the female through the higher development of decorative characters, of song, or of scent-producing glands. The best equipped males will thus crowd out the less well-equipped in the matter of reproduction, and thus the relevant characters will be increased and perfected through sexual selection. It is, of course, a necessary assumption that these secondary sexual characters may be transmitted to the female, although perhaps in rudimentary form. As we have said, this theory of sexual selection takes up a great deal of space in Darwin's book, and it need only be considered here in so far as Darwin applied it to the descent of man. To this latter problem the whole of Part I is devoted, while Part III contains a discussion of sexual selection in relation to man, and a general summary. Part II treats of sexual selection in general, and may be disregarded in our present study. Moreover, many interesting details must necessarily be passed over in what follows, for want of space. The first part of the "Descent of Man" begins with an enumeration of the proofs of the animal descent of man taken from the structure of the human body. Darwin chiefly emphasises the fact that the human body consists of the same organs and of the same tissues as those of the other mammals; he shows also that man is subject to the same diseases and tormented by the same parasites as the apes. He further dwells on the general agreement exhibited by young, embryonic forms, and he illustrates this by two figures placed one above the other, one representing a human embryo, after Eaker, the other a dog embryo, after Bischoff. ("Descent of Man" (Popular Edition, 1901), fig. 1, page 14.) Darwin finds further proofs of the animal origin of man in the reduced structures, in themselves extremely variable, which are either absolutely useless to their possessors, or of so little use that they could never have developed under existing conditions. Of such vestiges he enumerates: the defective development of the panniculus carnosus (muscle of the skin) so widely distributed among mammals, the ear-muscles, the occasional persistence of the animal ear-point in man, the rudimentary nictitating membrane (plica semilunaris) in the human eye, the slight development of the organ of smell, the general hairiness of the human body, the frequently defective development or entire absence of the third molar (the wisdom tooth), the vermiform appendix, the occasional reappearance of a bony canal (foramen supracondyloideum) at the lower end of the humerus, the rudimentary tail of man (the so-called taillessness), and so on. Of these rudimentary structures the occasional occurrence of the animal ear-point in man is most fully discussed. Darwin's attention was called to this interesting structure by the sculptor Woolner. He figures such a case observed in man, and also the head of an alleged orang-foetus, the photograph of which he received from Nitsche. Darwin's interpretation of Woolner's case as having arisen through a folding over of the free edge of a pointed ear has been fully borne out by my investigations on the external ear. (G. Schwalbe, "Das Darwin'sche Spitzohr beim menschlichen Embryo", "Anatom. Anzeiger", 1889, pages 176-189, and other papers.) In particular, it was established by these investigations that the human foetus, about the middle of its embryonic life, possesses a pointed ear somewhat similar to that of the monkey genus Macacus. One of Darwin's statements in regard to the head of the orang-foetus must be corrected. A LARGE ear with a point is shown in the photograph ("Descent of Man", fig.3, page 24.), but it can easily be demonstrated--and Deniker has already pointed this out--that the figure is not that of an orang-foetus at all, for that form has much smaller ears with no point; nor can it be a gibbon-foetus, as Deniker supposes, for the gibbon ear is also without a point. I myself regard it as that of a Macacus-embryo. But this mistake, which is due to Nitsche, in no way affects the fact recognised by Darwin, that ear-forms showing the point characteristic of the animal ear occur in man with extraordinary frequency. Finally, there is a discussion of those rudimentary structures which occur only in ONE sex, such as the rudimentary mammary glands in the male, the vesicula prostatica, which corresponds to the uterus of the female, and others. All these facts tell in favour of the common descent of man and all other vertebrates. The conclusion of this section is characteristic: "IT IS ONLY OUR NATURAL PREJUDICE, AND THAT ARROGANCE WHICH MADE OUR FOREFATHERS DECLARE THAT THEY WERE DESCENDED FROM DEMI-GODS, WHICH LEADS US TO DEMUR TO THIS CONCLUSION. BUT THE TIME WILL BEFORE LONG COME, WHEN IT WILL BE THOUGHT WONDERFUL THAT NATURALISTS, WHO WERE WELL ACQUAINTED WITH THE COMPARATIVE STRUCTURE AND DEVELOPMENT OF MAN, AND OTHER MAMMALS, SHOULD HAVE BELIEVED THAT EACH WAS THE WORK OF A SEPARATE ACT OF CREATION." (Ibid. page 36.) In the second chapter there is a more detailed discussion, again based upon an extraordinary wealth of facts, of the problem as to the manner in which, and the causes through which, man evolved from a lower form. Precisely the same causes are here suggested for the origin of man, as for the origin of species in general. Variability, which is a necessary assumption in regard to all transformations, occurs in man to a high degree. Moreover, the rapid multiplication of the human race creates conditions which necessitate an energetic struggle for existence, and thus afford scope for the intervention of natural selection. Of the exercise of ARTIFICIAL selection in the human race, there is nothing to be said, unless we cite such cases as the grenadiers of Frederick William I, or the population of ancient Sparta. In the passages already referred to and in those which follow, the transmission of acquired characters, upon which Darwin does not dwell, is taken for granted. In man, direct effects of changed conditions can be demonstrated (for instance in regard to bodily size), and there are also proofs of the influence exerted on his physical constitution by increased use or disuse. Reference is here made to the fact, established by Forbes, that the Quechua-Indians of the high plateaus of Peru show a striking development of lungs and thorax, as a result of living constantly at high altitudes. Such special forms of variation as arrests of development (microcephalism) and reversion to lower forms are next discussed. Darwin himself felt ("Descent of Man", page 54.) that these subjects are so nearly related to the cases mentioned in the first chapter, that many of them might as well have been dealt with there. It seems to me that it would have been better so, for the citation of additional instances of reversion at this place rather disturbs the logical sequence of his ideas as to the conditions which have brought about the evolution of man from lower forms. The instances of reversion here discussed are microcephalism, which Darwin wrongly interpreted as atavistic, supernumerary mammae, supernumerary digits, bicornuate uterus, the development of abnormal muscles, and so on. Brief mention is also made of correlative variations observed in man. Darwin next discusses the question as to the manner in which man attained to the erect position from the state of a climbing quadruped. Here again he puts the influence of Natural Selection in the first rank. The immediate progenitors of man had to maintain a struggle for existence in which success was to the more intelligent, and to those with social instincts. The hand of these climbing ancestors, which had little skill and served mainly for locomotion, could only undergo further development when some early member of the Primate series came to live more on the ground and less among trees. A bipedal existence thus became possible, and with it the liberation of the hand from locomotion, and the one-sided development of the human foot. The upright position brought about correlated variations in the bodily structure; with the free use of the hand it became possible to manufacture weapons and to use them; and this again resulted in a degeneration of the powerful canine teeth and the jaws, which were then no longer necessary for defence. Above all, however, the intelligence immediately increased, and with it skull and brain. The nakedness of man, and the absence of a tail (rudimentariness of the tail vertebrae) are next discussed. Darwin is inclined to attribute the nakedness of man, not to the action of natural selection on ancestors who originally inhabited a tropical land, but to sexual selection, which, for aesthetic reasons, brought about the loss of the hairy covering in man, or primarily in woman. An interesting discussion of the loss of the tail, which, however, man shares with the anthropoid apes, some other monkeys and lemurs, forms the conclusion of the almost superabundant material which Darwin worked up in the second chapter. His object was to show that some of the most distinctive human characters are in all probability directly or indirectly due to natural selection. With characteristic modesty he adds ("Descent of Man", page 92.): "Hence, if I have erred in giving to natural selection great power, which I am very far from admitting, or in having exaggerated its power, which is in itself probable, I have at least, as I hope, done good service in aiding to overthrow the dogma of separate creations." At the end of the chapter he touches upon the objection as to man's helpless and defenceless condition. Against this he urges his intelligence and social instincts. The two following chapters contain a detailed discussion of the objections drawn from the supposed great differences between the mental powers of men and animals. Darwin at once admits that the differences are enormous, but not that any fundamental difference between the two can be found. Very characteristic of him is the following passage: "In what manner the mental powers were first developed in the lowest organisms, is as hopeless an enquiry as how life itself first originated. These are problems for the distant future, if they are ever to be solved by man." (Ibid. page 100.) After some brief observations on instinct and intelligence, Darwin brings forward evidence to show that the greater number of the emotional states, such as pleasure and pain, happiness and misery, love and hate are common to man and the higher animals. He goes on to give various examples showing that wonder and curiosity, imitation, attention, memory and imagination (dreams of animals), can also be observed in the higher mammals, especially in apes. In regard even to reason there are no sharply defined limits. A certain faculty of deliberation is characteristic of some animals, and the more thoroughly we know an animal the more intelligence we are inclined to credit it with. Examples are brought forward of the intelligent and deliberate actions of apes, dogs and elephants. But although no sharply defined differences exist between man and animals, there is, nevertheless, a series of other mental powers which are characteristics usually regarded as absolutely peculiar to man. Some of these characteristics are examined in detail, and it is shown that the arguments drawn from them are not conclusive. Man alone is said to be capable of progressive improvement; but against this must be placed as something analogous in animals, the fact that they learn cunning and caution through long continued persecution. Even the use of tools is not in itself peculiar to man (monkeys use sticks, stones and twigs), but man alone fashions and uses implements DESIGNED FOR A SPECIAL PURPOSE. In this connection the remarks taken from Lubbock in regard to the origin and gradual development of the earliest flint implements will be read with interest; these are similar to the observations on modern eoliths, and their bearing on the development of the stone-industry. It is interesting to learn from a letter to Hooker ("Life and Letters", Vol. II. page 161, June 22, 1859.), that Darwin himself at first doubted whether the stone implements discovered by Boucher de Perthes were really of the nature of tools. With the relentless candour as to himself which characterised him, he writes four years later in a letter to Lyell in regard to this view of Boucher de Perthes' discoveries: "I know something about his errors, and looked at his book many years ago, and am ashamed to think that I concluded the whole was rubbish! Yet he has done for man something like what Agassiz did for glaciers." (Ibid. Vol. III. page 15, March 17, 1863.) To return to Darwin's further comparisons between the higher mental powers of man and animals. He takes much of the force from the argument that man alone is capable of abstraction and self-consciousness by his own observations on dogs. One of the main differences between man and animals, speech, receives detailed treatment. He points out that various animals (birds, monkeys, dogs) have a large number of different sounds for different emotions, that, further, man produces in common with animals a whole series of inarticulate cries combined with gestures, and that dogs learn to understand whole sentences of human speech. In regard to human language, Darwin expresses a view contrary to that held by Max Muller ("Descent of Man", page 132.): "I cannot doubt that language owes its origin to the imitation and modification of various natural sounds, the voices of other animals, and man's own instinctive cries, aided by signs and gestures." The development of actual language presupposes a higher degree of intelligence than is found in any kind of ape. Darwin remarks on this point (Ibid. pages 136, 137.): "The fact of the higher apes not using their vocal organs for speech no doubt depends on their intelligence not having been sufficiently advanced." The sense of beauty, too, has been alleged to be peculiar to man. In refutation of this assertion Darwin points to the decorative colours of birds, which are used for display. And to the last objection, that man alone has religion, that he alone has a belief in God, it is answered "that numerous races have existed, and still exist, who have no idea of one or more gods, and who have no words in their languages to express such an idea." (Ibid. page 143.) The result of the investigations recorded in this chapter is to show that, great as the difference in mental powers between man and the higher animals may be, it is undoubtedly only a difference "of degree and not of kind." ("Descent of Man", page 193.) In the fourth chapter Darwin deals with the MORAL SENSE or CONSCIENCE, which is the most important of all differences between man and animals. It is a result of social instincts, which lead to sympathy for other members of the same society, to non-egoistic actions for the good of others. Darwin shows that social tendencies are found among many animals, and that among these love and kin-sympathy exist, and he gives examples of animals (especially dogs) which may exhibit characters that we should call moral in man (e.g. disinterested self-sacrifice for the sake of others). The early ape-like progenitors of the human race were undoubtedly social. With the increase of intelligence the moral sense develops farther; with the acquisition of speech public opinion arises, and finally, moral sense becomes habit. The rest of Darwin's detailed discussions on moral philosophy may be passed over. The fifth chapter may be very briefly summarised. In it Darwin shows that the intellectual and moral faculties are perfected through natural selection. He inquires how it can come about that a tribe at a low level of evolution attains to a higher, although the best and bravest among them often pay for their fidelity and courage with their lives without leaving any descendants. In this case it is the sentiment of glory, praise and blame, the admiration of others, which bring about the increase of the better members of the tribe. Property, fixed dwellings, and the association of families into a community are also indispensable requirements for civilisation. In the longer second section of the fifth chapter Darwin acts mainly as recorder. On the basis of numerous investigations, especially those of Greg, Wallace, and Galton, he inquires how far the influence of natural selection can be demonstrated in regard to civilised nations. In the final section, which deals with the proofs that all civilised nations were once barbarians, Darwin again uses the results gained by other investigators, such as Lubbock and Tylor. There are two sets of facts which prove the proposition in question. In the first place, we find traces of a former lower state in the customs and beliefs of all civilised nations, and in the second place, there are proofs to show that savage races are independently able to raise themselves a few steps in the scale of civilisation, and that they have thus raised themselves. In the sixth chapter of the work, Morphology comes into the foreground once more. Darwin first goes back, however, to the argument based on the great difference between the mental powers of the highest animals and those of man. That this is only quantitative, not qualitative, he has already shown. Very instructive in this connection is the reference to the enormous difference in mental powers in another class. No one would draw from the fact that the cochineal insect (Coccus) and the ant exhibit enormous differences in their mental powers, the conclusion that the ant should therefore be regarded as something quite distinct, and withdrawn from the class of insects altogether. Darwin next attempts to establish the SPECIFIC genealogical tree of man, and carefully weighs the differences and resemblances between the different families of the Primates. The erect position of man is an adaptive character, just as are the various characters referable to aquatic life in the seals, which, notwithstanding these, are ranked as a mere family of the Carnivores. The following utterance is very characteristic of Darwin ("Descent of Man", page 231.): "If man had not been his own classifier, he would never have thought of founding a separate order for his own reception." In numerous characters not mentioned in systematic works, in the features of the face, in the form of the nose, in the structure of the external ear, man resembles the apes. The arrangement of the hair in man has also much in common with the apes; as also the occurrence of hair on the forehead of the human embryo, the beard, the convergence of the hair of the upper and under arm towards the elbow, which occurs not only in the anthropoid apes, but also in some American monkeys. Darwin here adopts Wallace's explanation of the origin of the ascending direction of the hair in the forearm of the orang,--that it has arisen through the habit of holding the hands over the head in rain. But this explanation cannot be maintained when we consider that this disposition of the hair is widely distributed among the most different mammals, being found in the dog, in the sloth, and in many of the lower monkeys. After further careful analysis of the anatomical characters Darwin reaches the conclusion that the New World monkeys (Platyrrhine) may be excluded from the genealogical tree altogether, but that man is an offshoot from the Old World monkeys (Catarrhine) whose progenitors existed as far back as the Miocene period. Among these Old World monkeys the forms to which man shows the greatest resemblance are the anthropoid apes, which, like him, possess neither tail nor ischial callosities. The platyrrhine and catarrhine monkeys have their primitive ancestor among extinct forms of the Lemuridae. Darwin also touches on the question of the original home of the human race and supposes that it may have been in Africa, because it is there that man's nearest relatives, the gorilla and the chimpanzee, are found. But he regards speculation on this point as useless. It is remarkable that, in this connection, Darwin regards the loss of the hair-covering in man as having some relation to a warm climate, while elsewhere he is inclined to make sexual selection responsible for it. Darwin recognises the great gap between man and his nearest relatives, but similar gaps exist at other parts of the mammalian genealogical tree: the allied forms have become extinct. After the extermination of the lower races of mankind, on the one hand, and of the anthropoid apes on the other, which will undoubtedly take place, the gulf will be greater than ever, since the baboons will then bound it on the one side, and the white races on the other. Little weight need be attached to the lack of fossil remains to fill up this gap, since the discovery of these depends upon chance. The last part of the chapter is devoted to a discussion of the earlier stages in the genealogy of man. Here Darwin accepts in the main the genealogical tree, which had meantime been published by Haeckel, who traces the pedigree back through Monotremes, Reptiles, Amphibians, and Fishes, to Amphioxus. Then follows an attempt to reconstruct, from the atavistic characters, a picture of our primitive ancestor who was undoubtedly an arboreal animal. The occurrence of rudiments of parts in one sex which only come to full development in the other is next discussed. This state of things Darwin regards as derived from an original hermaphroditism. In regard to the mammary glands of the male he does not accept the theory that they are vestigial, but considers them rather as not fully developed. The last chapter of Part I deals with the question whether the different races of man are to be regarded as different species, or as sub-species of a race of monophyletic origin. The striking differences between the races are first emphasised, and the question of the fertility or infertility of hybrids is discussed. That fertility is the more usual is shown by the excessive fertility of the hybrid population of Brazil. This, and the great variability of the distinguishing characters of the different races, as well as the fact that all grades of transition stages are found between these, while considerable general agreement exists, tell in favour of the unity of the races and lead to the conclusion that they all had a common primitive ancestor. Darwin therefore classifies all the different races as sub-species of ONE AND THE SAME SPECIES. Then follows an interesting inquiry into the reasons for the extinction of human races. He recognises as the ultimate reason the injurious effects of a change of the conditions of life, which may bring about an increase in infantile mortality, and a diminished fertility. It is precisely the reproductive system, among animals also, which is most susceptible to changes in the environment. The final section of this chapter deals with the formation of the races of mankind. Darwin discusses the question how far the direct effect of different conditions of life, or the inherited effects of increased use or disuse may have brought about the characteristic differences between the different races. Even in regard to the origin of the colour of the skin he rejects the transmitted effects of an original difference of climate as an explanation. In so doing he is following his tendency to exclude Lamarckian explanations as far as possible. But here he makes gratuitous difficulties from which, since natural selection fails, there is no escape except by bringing in the principle of sexual selection, to which, he regarded it as possible, skin-colouring, arrangement of hair, and form of features might be traced. But with his characteristic conscientiousness he guards himself thus: "I do not intend to assert that sexual selection will account for all the differences between the races." ("Descent of Man", page 308.) I may be permitted a remark as to Darwin's attitude towards Lamarck. While, at an earlier stage, when he was engaged in the preliminary labours for his immortal work, "The Origin of Species", Darwin expresses himself very forcibly against the views of Lamarck, speaking of Lamarckian "nonsense," ("Life and Letters", Vol. II. page 23.), and of Lamarck's "absurd, though clever work" (Loc. cit. page 39.) and expressly declaring, "I attribute very little to the direct action of climate, etc." (Loc. cit. (1856), page 82.) yet in later life he became more and more convinced of the influence of external conditions. In 1876, that is, two years after the appearance of the second edition of "The Descent of Man", he writes with his usual candid honesty: "In my opinion the greatest error which I have committed, has been not allowing sufficient weight to the direct action of the environment, i.e. food, climate, etc. independently of natural selection." (Ibid. Vol. III. page 159.) It is certain from this change of opinion that, if he had been able to make up his mind to issue a third edition of "The Descent of Man", he would have ascribed a much greater influence to the effect of external conditions in explaining the different characters of the races of man than he did in the second edition. He would also undoubtedly have attributed less influence to sexual selection as a factor in the origin of the different bodily characteristics, if indeed he would not have excluded it altogether. In Part III of the "Descent" two additional chapters are devoted to the discussion of sexual selection in relation to man. These may be very briefly referred to. Darwin here seeks to show that sexual selection has been operative on man and his primitive progenitor. Space fails me to follow out his interesting arguments. I can only mention that he is inclined to trace back hairlessness, the development of the beard in man, and the characteristic colour of the different human races to sexual selection. Since bareness of the skin could be no advantage, but rather a disadvantage, this character cannot have been brought about by natural selection. Darwin also rejected a direct influence of climate as a cause of the origin of the skin-colour. I have already expressed the opinion, based on the development of his views as shown in his letters, that in a third edition Darwin would probably have laid more stress on the influence of external environment. He himself feels that there are gaps in his proofs here, and says in self-criticism: "The views here advanced, on the part which sexual selection has played in the history of man, want scientific precision." ("Descent of Man", page 924.) I need here only point out that it is impossible to explain the graduated stages of skin-colour by sexual selection, since it would have produced races sharply defined by their colour and not united to other races by transition stages, and this, it is well known, is not the case. Moreover, the fact established by me ("Die Hautfarbe des Menschen", "Mitteilungen der Anthropologischen Gesellschaft in Wien", Vol. XXXIV. pages 331-352.), that in all races the ventral side of the trunk is paler than the dorsal side, and the inner surface of the extremities paler than the outer side, cannot be explained by sexual selection in the Darwinian sense. With this I conclude my brief survey of the rich contents of Darwin's book. I may be permitted to conclude by quoting the magnificent final words of "The Descent of Man": "We must, however, acknowledge, as it seems to me, that man, with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system--with all these exalted powers--Man still bears in his bodily frame the indelible stamp of his lowly origin." (Ibid. page 947.) What has been the fate of Darwin's doctrines since his great achievement? How have they been received and followed up by the scientific and lay world? And what do the successors of the mighty hero and genius think now in regard to the origin of the human race? At the present time we are incomparably more favourably placed than Darwin was for answering this question of all questions. We have at our command an incomparably greater wealth of material than he had at his disposal. And we are more fortunate than he in this respect, that we now know transition-forms which help to fill up the gap, still great, between the lowest human races and the highest apes. Let us consider for a little the more essential additions to our knowledge since the publication of "The Descent of Man". Since that time our knowledge of animal embryos has increased enormously. While Darwin was obliged to content himself with comparing a human embryo with that of a dog, there are now available the youngest embryos of monkeys of all possible groups (Orang, Gibbon, Semnopithecus, Macacus), thanks to Selenka's most successful tour in the East Indies in search of such material. We can now compare corresponding stages of the lower monkeys and of the Anthropoid apes with human embryos, and convince ourselves of their great resemblance to one another, thus strengthening enormously the armour prepared by Darwin in defence of his view on man's nearest relatives. It may be said that Selenka's material fils up the blanks in Darwin's array of proofs in the most satisfactory manner. The deepening of our knowledge of comparative anatomy also gives us much surer foundations than those on which Darwin was obliged to build. Just of late there have been many workers in the domain of the anatomy of apes and lemurs, and their investigations extend to the most different organs. Our knowledge of fossil apes and lemurs has also become much wider and more exact since Darwin's time: the fossil lemurs have been especially worked up by Cope, Forsyth Major, Ameghino, and others. Darwin knew very little about fossil monkeys. He mentions two or three anthropoid apes as occurring in the Miocene of Europe ("Descent of Man", page 240.), but only names Dryopithecus, the largest form from the Miocene of France. It was erroneously supposed that this form was related to Hylobates. We now know not only a form that actually stands near to the gibbon (Pliopithecus), and remains of other anthropoids (Pliohylobates and the fossil chimpanzee, Palaeopithecus), but also several lower catarrhine monkeys, of which Mesopithecus, a form nearly related to the modern Sacred Monkeys (a species of Semnopithecus) and found in strata of the Miocene period in Greece, is the most important. Quite recently, too, Ameghino's investigations have made us acquainted with fossil monkeys from South America (Anthropops, Homunculus), which, according to their discoverer, are to be regarded as in the line of human descent. What Darwin missed most of all--intermediate forms between apes and man--has been recently furnished. (E. Dubois, as is well known, discovered in 1893, near Trinil in Java, in the alluvial deposits of the river Bengawan, an important form represented by a skull-cap, some molars, and a femur. His opinion--much disputed as it has been--that in this form, which he named Pithecanthropus, he has found a long-desired transition-form is shared by the present writer. And although the geological age of these fossils, which, according to Dubois, belong to the uppermost Tertiary series, the Pliocene, has recently been fixed at a later date (the older Diluvium)), the MORPHOLOGICAL VALUE of these interesting remains, that is, the intermediate position of Pithecanthropus, still holds good. Volz says with justice ("Das geologische Alter der Pithecanthropus-Schichten bei Trinil, Ost-Java". "Neues Jahrb. f.Mineralogie". Festband, 1907.), that even if Pithecanthropus is not THE missing link, it is undoubtedly _A_ missing link. As on the one hand there has been found in Pithecanthropus a form which, though intermediate between apes and man, is nevertheless more closely allied to the apes, so on the other hand, much progress has been made since Darwin's day in the discovery and description of the older human remains. Since the famous roof of a skull and the bones of the extremities belonging to it were found in 1856 in the Neandertal near Dusseldorf, the most varied judgments have been expressed in regard to the significance of the remains and of the skull in particular. In Darwin's "Descent of Man" there is only a passing allusion to them ("Descent of Man", page 82.) in connection with the discussion of the skull-capacity, although the investigations of Schaaffhausen, King, and Huxley were then known. I believe I have shown, in a series of papers, that the skull in question belongs to a form different from any of the races of man now living, and, with King and Cope, I regard it as at least a different species from living man, and have therefore designated it Homo primigenius. The form unquestionably belongs to the older Diluvium, and in the later Diluvium human forms already appear, which agree in all essential points with existing human races. As far back as 1886 the value of the Neandertal skull was greatly enhanced by Fraipont's discovery of two skulls and skeletons from Spy in Belgium. These are excellently described by their discoverer ("La race humaine de Neanderthal ou de Canstatt en Belgique". "Arch. de Biologie", VII. 1887.), and are regarded as belonging to the same group of forms as the Neandertal remains. In 1899 and the following years came the discovery by Gorjanovic-Kramberger of different skeletal parts of at least ten individuals in a cave near Krapina in Croatia. (Gorjanovic-Kramberger "Der diluviale Mensch von Krapina in Kroatien", 1906.) It is in particular the form of the lower jaw which is different from that of all recent races of man, and which clearly indicates the lowly position of Homo primigenius, while, on the other hand, the long-known skull from Gibraltar, which I ("Studien zur Vorgeschichte des Menschen", 1906, pages 154 ff.) have referred to Homo primigenius, and which has lately been examined in detail by Sollas ("On the cranial and facial characters of the Neandertal Race". "Trans. R. Soc." London, vol. 199, 1908, page 281.), has made us acquainted with the surprising shape of the eye-orbit, of the nose, and of the whole upper part of the face. Isolated lower jaws found at La Naulette in Belgium, and at Malarnaud in France, increase our material which is now as abundant as could be desired. The most recent discovery of all is that of a skull dug up in August of this year (1908) by Klaatsch and Hauser in the lower grotto of the Le Moustier in Southern France, but this skull has not yet been fully described. Thus Homo primigenius must also be regarded as occupying a position in the gap existing between the highest apes and the lowest human races, Pithecanthropus, standing in the lower part of it, and Homo primigenius in the higher, near man. In order to prevent misunderstanding, I should like here to emphasise that in arranging this structural series--anthropoid apes, Pithecanthropus, Homo primigenius, Homo sapiens--I have no intention of establishing it as a direct genealogical series. I shall have something to say in regard to the genetic relations of these forms, one to another, when discussing the different theories of descent current at the present day. ((Since this essay was written Schoetensack has discovered near Heidelberg and briefly described an exceedingly interesting lower jaw from rocks between the Pliocene and Diluvial beds. This exhibits interesting differences from the forms of lower jaw of Homo primigenius. (Schoetensack "Der Unterkiefer des Homo heidelbergensis". Leipzig, 1908.) G.S.)) In quite a different domain from that of morphological relationship, namely in the physiological study of the blood, results have recently been gained which are of the highest importance to the doctrine of descent. Uhlenhuth, Nuttall, and others have established the fact that the blood-serum of a rabbit which has previously had human blood injected into it, forms a precipitate with human blood. This biological reaction was tried with a great variety of mammalian species, and it was found that those far removed from man gave no precipitate under these conditions. But as in other cases among mammals all nearly related forms yield an almost equally marked precipitate, so the serum of a rabbit treated with human blood and then added to the blood of an anthropoid ape gives ALMOST as marked a precipitate as in human blood; the reaction to the blood of the lower Eastern monkeys is weaker, that to the Western monkeys weaker still; indeed in this last case there is only a slight clouding after a considerable time and no actual precipitate. The blood of the Lemuridae (Nuttall) gives no reaction or an extremely weak one, that of the other mammals none whatever. We have in this not only a proof of the literal blood-relationship between man and apes, but the degree of relationship with the different main groups of apes can be determined beyond possibility of mistake. Finally, it must be briefly mentioned that in regard to remains of human handicraft also, the material at our disposal has greatly increased of late years, that, as a result of this, the opinions of archaeologists have undergone many changes, and that, in particular, their views in regard to the age of the human race have been greatly influenced. There is a tendency at the present time to refer the origin of man back to Tertiary times. It is true that no remains of Tertiary man have been found, but flints have been discovered which, according to the opinion of most investigators, bear traces either of use, or of very primitive workmanship. Since Rutot's time, following Mortillet's example, investigators have called these "eoliths," and they have been traced back by Verworn to the Miocene of the Auvergne, and by Rutot even to the upper Oligocene. Although these eoliths are even nowadays the subject of many different views, the preoccupation with them has kept the problem of the age of the human race continually before us. Geology, too, has made great progress since the days of Darwin and Lyell, and has endeavoured with satisfactory results to arrange the human remains of the Diluvial period in chronological order (Penck). I do not intend to enter upon the question of the primitive home of the human race; since the space at my disposal will not allow of my touching even very briefly upon all the departments of science which are concerned in the problem of the descent of man. How Darwin would have rejoiced over each of the discoveries here briefly outlined! What use he would have made of the new and precious material, which would have prevented the discouragement from which he suffered when preparing the second edition of "The Descent of Man"! But it was not granted to him to see this progress towards filling up the gaps in his edifice of which he was so painfully conscious. He did, however, have the satisfaction of seeing his ideas steadily gaining ground, notwithstanding much hostility and deep-rooted prejudice. Even in the years between the appearance of "The Origin of Species" and of the first edition of the "Descent", the idea of a natural descent of man, which was only briefly indicated in the work of 1859, had been eagerly welcomed in some quarters. It has been already pointed out how brilliantly Huxley contributed to the defence and diffusion of Darwin's doctrines, and how in "Man's Place in Nature" he has given us a classic work as a foundation for the doctrine of the descent of man. As Huxley was Darwin's champion in England, so in Germany Carl Vogt, in particular, made himself master of the Darwinian ideas. But above all it was Haeckel who, in energy, eagerness for battle, and knowledge may be placed side by side with Huxley, who took over the leadership in the controversy over the new conception of the universe. As far back as 1866, in his "Generelle Morphologie", he had inquired minutely into the question of the descent of man, and not content with urging merely the general theory of descent from lower animal forms, he drew up for the first time genealogical trees showing the close relationships of the different animal groups; the last of these illustrated the relationships of Mammals, and among them of all groups of the Primates, including man. It was Haeckel's genealogical trees that formed the basis of the special discussion of the relationships of man, in the sixth chapter of Darwin's "Descent of Man". In the last section of this essay I shall return to Haeckel's conception of the special descent of man, the main features of which he still upholds, and rightly so. Haeckel has contributed more than any one else to the spread of the Darwinian doctrine. I can only allow myself a few words as to the spread of the theory of the natural descent of man in other countries. The Parisian anthropological school, founded and guided by the genius of Broca, took up the idea of the descent of man, and made many notable contributions to it (Broca, Manouvrier, Mahoudeau, Deniker and others). In England itself Darwin's work did not die. Huxley took care of that, for he, with his lofty and unprejudiced mind, dominated and inspired English biology until his death on June 29, 1895. He had the satisfaction shortly before his death of learning of Dubois' discovery, which he illustrated by a humorous sketch. ("Life and Letters of Thomas Henry Huxley", Vol. II. page 394.) But there are still many followers in Darwin's footsteps in England. Keane has worked at the special genealogical tree of the Primates; Keith has inquired which of the anthropoid apes has the greatest number of characters in common with man; Morris concerns himself with the evolution of man in general, especially with his acquisition of the erect position. The recent discoveries of Pithecanthropus and Homo primigenius are being vigorously discussed; but the present writer is not in a position to form an opinion of the extent to which the idea of descent has penetrated throughout England generally. In Italy independent work in the domain of the descent of man is being produced, especially by Morselli; with him are associated, in the investigation of related problems, Sergi and Giuffrida-Ruggeri. From the ranks of American investigators we may single out in particular the eminent geologist Cope, who championed with much decision the idea of the specific difference of Homo neandertalensis (primigenius) and maintained a more direct descent of man from the fossil Lemuridae. In South America too, in Argentina, new life is stirring in this department of science. Ameghino in Buenos Ayres has awakened the fossil primates of the Pampas formation to new life; he even believes that in Tetraprothomo, represented by a femur, he has discovered a direct ancestor of man. Lehmann-Nitsche is working at the other side of the gulf between apes and men, and he describes a remarkable first cervical vertebra (atlas) from Monte Hermoso as belonging to a form which may bear the same relation to Homo sapiens in South America as Homo primigenius does in the Old World. After a minute investigation he establishes a human species Homo neogaeus, while Ameghino ascribes this atlas vertebra to his Tetraprothomo. Thus throughout the whole scientific world there is arising a new life, an eager endeavour to get nearer to Huxley's problema maximum, to penetrate more deeply into the origin of the human race. There are to-day very few experts in anatomy and zoology who deny the animal descent of man in general. Religious considerations, old prejudices, the reluctance to accept man, who so far surpasses mentally all other creatures, as descended from "soulless" animals, prevent a few investigators from giving full adherence to the doctrine. But there are very few of these who still postulate a special act of creation for man. Although the majority of experts in anatomy and zoology accept unconditionally the descent of man from lower forms, there is much diversity of opinion among them in regard to the special line of descent. In trying to establish any special hypothesis of descent, whether by the graphic method of drawing up genealogical trees or otherwise, let us always bear in mind Darwin's words ("Descent of Man", page 229.) and use them as a critical guiding line: "As we have no record of the lines of descent, the pedigree can be discovered only by observing the degrees of resemblance between the beings which are to be classed." Darwin carries this further by stating "that resemblances in several unimportant structures, in useless and rudimentary organs, or not now functionally active, or in an embryological condition, are by far the most serviceable for classification." (Loc. cit.) It has also to be remembered that NUMEROUS separate points of agreement are of much greater importance than the amount of similarity or dissimilarity in a few points. The hypotheses as to descent current at the present day may be divided into two main groups. The first group seeks for the roots of the human race not among any of the families of the apes--the anatomically nearest forms--nor among their very similar but less specialised ancestral forms, the fossil representatives of which we can know only in part, but, setting the monkeys on one side, it seeks for them lower down among the fossil Eocene Pseudo-lemuridae or Lemuridae (Cope), or even among the primitive pentadactylous Eocene forms, which may either have led directly to the evolution of man (Adloff), or have given rise to an ancestral form common to apes and men (Klaatsch (Klaatsch in his last publications speaks in the main only of an ancestral form common to men and anthropoid apes.), Giuffrida-Ruggeri). The common ancestral form, from which man and apes are thus supposed to have arisen independently, may explain the numerous resemblances which actually exist between them. That is to say, all the characters upon which the great structural resemblance between apes and man depends must have been present in their common ancestor. Let us take an example of such a common character. The bony external ear-passage is in general as highly developed in the lower Eastern monkeys and the anthropoid apes as in man. This character must, therefore, have already been present in the common primitive form. In that case it is not easy to understand why the Western monkeys have not also inherited the character, instead of possessing only a tympanic ring. But it becomes more intelligible if we assume that forms with a primitive tympanic ring were the original type, and that from these were evolved, on the one hand, the existing New World monkeys with persistent tympanic ring, and on the other an ancestral form common to the lower Old World monkeys, the anthropoid apes and man. For man shares with these the character in question, and it is also one of the "unimportant" characters required by Darwin. Thus we have two divergent lines arising from the ancestral form, the Western monkeys (Platyrrhine) on the one hand, and an ancestral form common to the lower Eastern monkeys, the anthropoid apes, and man, on the other. But considerations similar to those which showed it to be impossible that man should have developed from an ancestor common to him and the monkeys, yet outside of and parallel with these, may be urged also against the likelihood of a parallel evolution of the lower Eastern monkeys, the anthropoid apes, and man. The anthropoid apes have in common with man many characters which are not present in the lower Old World monkeys. These characters must therefore have been present in the ancestral form common to the three groups. But here, again, it is difficult to understand why the lower Eastern monkeys should not also have inherited these characters. As this is not the case, there remains no alternative but to assume divergent evolution from an indifferent form. The lower Eastern monkeys are carrying on the evolution in one direction--I might almost say towards a blind alley--while anthropoids and men have struck out a progressive path, at first in common, which explains the many points of resemblance between them, without regarding man as derived directly from the anthropoids. Their many striking points of agreement indicate a common descent, and cannot be explained as phenomena of convergence. I believe I have shown in the above sketch that a theory which derives man directly from lower forms without regarding apes as transition-types leads ad absurdum. The close structural relationship between man and monkeys can only be understood if both are brought into the same line of evolution. To trace man's line of descent directly back to the old Eocene mammals, alongside of, but with no relation to these very similar forms, is to abandon the method of exact comparison, which, as Darwin rightly recognised, alone justifies us in drawing up genealogical trees on the basis of resemblances and differences. The farther down we go the more does the ground slip from beneath our feet. Even the Lemuridae show very numerous divergent conditions, much more so the Eocene mammals (Creodonta, Condylarthra), the chief resemblance of which to man consists in the possession of pentadactylous hands and feet! Thus the farther course of the line of descent disappears in the darkness of the ancestry of the mammals. With just as much reason we might pass by the Vertebrates altogether, and go back to the lower Invertebrates, but in that case it would be much easier to say that man has arisen independently, and has evolved, without relation to any animals, from the lowest primitive form to his present isolated and dominant position. But this would be to deny all value to classification, which must after all be the ultimate basis of a genealogical tree. We can, as Darwin rightly observed, only infer the line of descent from the degree of resemblance between single forms. If we regard man as directly derived from primitive forms very far back, we have no way of explaining the many points of agreement between him and the monkeys in general, and the anthropoid apes in particular. These must remain an inexplicable marvel. I have thus, I trust, shown that the first class of special theories of descent, which assumes that man has developed, parallel with the monkeys, but without relation to them, from very low primitive forms cannot be upheld, because it fails to take into account the close structural affinity of man and monkeys. I cannot but regard this hypothesis as lamentably retrograde, for it makes impossible any application of the facts that have been discovered in the course of the anatomical and embryological study of man and monkeys, and indeed prejudges investigations of that class as pointless. The whole method is perverted; an unjustifiable theory of descent is first formulated with the aid of the imagination, and then we are asked to declare that all structural relations between man and monkeys, and between the different groups of the latter, are valueless,--the fact being that they are the only true basis on which a genealogical tree can be constructed. So much for this most modern method of classification, which has probably found adherents because it would deliver us from the relationship to apes which many people so much dislike. In contrast to it we have the second class of special hypotheses of descent, which keeps strictly to the nearest structural relationships. This is the only basis that justifies the drawing up of a special hypothesis of descent. If this fundamental proposition be recognised, it will be admitted that the doctrine of special descent upheld by Haeckel, and set forth in Darwin's "Descent of Man", is still valid to-day. In the genealogical tree, man's place is quite close to the anthropoid apes; these again have as their nearest relatives the lower Old World monkeys, and their progenitors must be sought among the less differentiated Platyrrhine monkeys, whose most important characters have been handed on to the present day New World monkeys. How the different genera are to be arranged within the general scheme indicated depends in the main on the classificatory value attributed to individual characters. This is particularly true in regard to Pithecanthropus, which I consider as the root of a branch which has sprung from the anthropoid ape root and has led up to man; the latter I have designated the family of the Hominidae. For the rest, there are, as we have said, various possible ways of constructing the narrower genealogy within the limits of this branch including men and apes, and these methods will probably continue to change with the accumulation of new facts. Haeckel himself has modified his genealogical tree of the Primates in certain details since the publication of his "Generelle Morphologie" in 1866, but its general basis remains the same. (Haeckel's latest genealogical tree is to be found in his most recent work, "Unsere Ahnenreihe". Jena, 1908.) All the special genealogical trees drawn up on the lines laid down by Haeckel and Darwin--and that of Dubois may be specially mentioned--are based, in general, on the close relationship of monkeys and men, although they may vary in detail. Various hypotheses have been formulated on these lines, with special reference to the evolution of man. "Pithecanthropus" is regarded by some authorities as the direct ancestor of man, by others as a side-track failure in the attempt at the evolution of man. The problem of the monophyletic or polyphyletic origin of the human race has also been much discussed. Sergi (Sergi G. "Europa", 1908.) inclines towards the assumption of a polyphyletic origin of the three main races of man, the African primitive form of which has given rise also to the gorilla and chimpanzee, the Asiatic to the Orang, the Gibbon, and Pithecanthropus. Kollmann regards existing human races as derived from small primitive races (pigmies), and considers that Homo primigenius must have arisen in a secondary and degenerative manner. But this is not the place, nor have I the space to criticise the various special theories of descent. One, however, must receive particular notice. According to Ameghino, the South American monkeys (Pitheculites) from the oldest Tertiary of the Pampas are the forms from which have arisen the existing American monkeys on the one hand, and on the other, the extinct South American Homunculidae, which are also small forms. From these last, anthropoid apes and man have, he believes, been evolved. Among the progenitors of man, Ameghino reckons the form discovered by him (Tetraprothomo), from which a South American primitive man, Homo pampaeus, might be directly evolved, while on the other hand all the lower Old World monkeys may have arisen from older fossil South American forms (Clenialitidae), the distribution of which may be explained by the bridge formerly existing between South America and Africa, as may be the derivation of all existing human races from Homo pampaeus. (See Ameghino's latest paper, "Notas preliminares sobre el Tetraprothomo argentinus", etc. "Anales del Museo nacional de Buenos Aires", XVI. pages 107-242, 1907.) The fossil forms discovered by Ameghino deserve the most minute investigation, as does also the fossil man from South America of which Lehmann-Nitsche ("Nouvelles recherches sur la formation pampeenne et l'homme fossile de la Republique Argentine". "Rivista del Museo de la Plata", T. XIV. pages 193-488.) has made a thorough study. It is obvious that, notwithstanding the necessity for fitting man's line of descent into the genealogical tree of the Primates, especially the apes, opinions in regard to it differ greatly in detail. This could not be otherwise, since the different Primate forms, especially the fossil forms, are still far from being exhaustively known. But one thing remains certain,--the idea of the close relationship between man and monkeys set forth in Darwin's "Descent of Man". Only those who deny the many points of agreement, the sole basis of classification, and thus of a natural genealogical tree, can look upon the position of Darwin and Haeckel as antiquated, or as standing on an insufficient foundation. For such a genealogical tree is nothing more than a summarised representation of what is known in regard to the degree of resemblance between the different forms. Darwin's work in regard to the descent of man has not been surpassed; the more we immerse ourselves in the study of the structural relationships between apes and man, the more is our path illumined by the clear light radiating from him, and through his calm and deliberate investigation, based on a mass of material in the accumulation of which he has never had an equal. Darwin's fame will be bound up for all time with the unprejudiced investigation of the question of all questions, the descent of the human race. VIII. CHARLES DARWIN AS AN ANTHROPOLOGIST. By Ernst Haeckel. Professor of Zoology in the University of Jena. The great advance that anthropology has made in the second half of the nineteenth century is due in the first place, to Darwin's discovery of the origin of man. No other problem in the whole field of research is so momentous as that of "Man's place in nature," which was justly described by Huxley (1863) as the most fundamental of all questions. Yet the scientific solution of this problem was impossible until the theory of descent had been established. It is now a hundred years since the great French biologist Jean Lamarck published his "Philosophie Zoologique". By a remarkable coincidence the year in which that work was issued, 1809, was the year of the birth of his most distinguished successor, Charles Darwin. Lamarck had already recognised that the descent of man from a series of other Vertebrates--that is, from a series of Ape-like Primates--was essentially involved in the general theory of transformation which he had erected on a broad inductive basis; and he had sufficient penetration to detect the agencies that had been at work in the evolution of the erect bimanous man from the arboreal and quadrumanous ape. He had, however, few empirical arguments to advance in support of his hypothesis, and it could not be established until the further development of the biological sciences--the founding of comparative embryology by Baer (1828) and of the cell-theory by Schleiden and Schwann (1838), the advance of physiology under Johannes Muller (1833), and the enormous progress of palaeontology and comparative anatomy between 1820 and 1860--provided this necessary foundation. Darwin was the first to coordinate the ample results of these lines of research. With no less comprehensiveness than discrimination he consolidated them as a basis of a modified theory of descent, and associated with them his own theory of natural selection, which we take to be distinctive of "Darwinism" in the stricter sense. The illuminating truth of these cumulative arguments was so great in every branch of biology that, in spite of the most vehement opposition, the battle was won within a single decade, and Darwin secured the general admiration and recognition that had been denied to his forerunner, Lamarck, up to the hour of his death (1829). Before, however, we consider the momentous influence that Darwinism has had in anthropology, we shall find it useful to glance at its history in the course of the last half century, and notice the various theories that have contributed to its advance. The first attempt to give extensive expression to the reform of biology by Darwin's work will be found in my "Generelle Morphologie" (1866) ("Generelle Morphologie der Organismen", 2 vols., Berlin, 1866.) which was followed by a more popular treatment of the subject in my "Naturliche Schopfungsgeschichte" (1868) (English translation; "The History of Creation", London, 1876.), a compilation from the earlier work. In the first volume of the "Generelle Morphologie" I endeavoured to show the great importance of evolution in settling the fundamental questions of biological philosophy, especially in regard to comparative anatomy. In the second volume I dealt broadly with the principle of evolution, distinguishing ontogeny and phylogeny as its two coordinate main branches, and associating the two in the Biogenetic Law. The Law may be formulated thus: "Ontogeny (embryology or the development of the individual) is a concise and compressed recapitulation of phylogeny (the palaeontological or genealogical series) conditioned by laws of heredity and adaptation." The "Systematic introduction to general evolution," with which the second volume of the "Generelle Morphologie" opens, was the first attempt to draw up a natural system of organisms (in harmony with the principles of Lamarck and Darwin) in the form of a hypothetical pedigree, and was provisionally set forth in eight genealogical tables. In the nineteenth chapter of the "Generelle Morphologie"--a part of which has been republished, without any alteration, after a lapse of forty years--I made a critical study of Lamarck's theory of descent and of Darwin's theory of selection, and endeavoured to bring the complex phenomena of heredity and adaptation under definite laws for the first time. Heredity I divided into conservative and progressive: adaptation into indirect (or potential) and direct (or actual). I then found it possible to give some explanation of the correlation of the two physiological functions in the struggle for life (selection), and to indicate the important laws of divergence (or differentiation) and complexity (or division of labour), which are the direct and inevitable outcome of selection. Finally, I marked off dysteleology as the science of the aimless (vestigial, abortive, atrophied, and useless) organs and parts of the body. In all this I worked from a strictly monistic standpoint, and sought to explain all biological phenomena on the mechanical and naturalistic lines that had long been recognised in the study of inorganic nature. Then (1866), as now, being convinced of the unity of nature, the fundamental identity of the agencies at work in the inorganic and the organic worlds, I discarded vitalism, teleology, and all hypotheses of a mystic character. It was clear from the first that it was essential, in the monistic conception of evolution, to distinguish between the laws of conservative and progressive heredity. Conservative heredity maintains from generation to generation the enduring characters of the species. Each organism transmits to its descendants a part of the morphological and physiological qualities that it has received from its parents and ancestors. On the other hand, progressive heredity brings new characters to the species--characters that were not found in preceding generations. Each organism may transmit to its offspring a part of the morphological and physiological features that it has itself acquired, by adaptation, in the course of its individual career, through the use or disuse of particular organs, the influence of environment, climate, nutrition, etc. At that time I gave the name of "progressive heredity" to this inheritance of acquired characters, as a short and convenient expression, but have since changed the term to "transformative heredity" (as distinguished from conservative). This term is preferable, as inherited regressive modifications (degeneration, retrograde metamorphisis, etc.) come under the same head. Transformative heredity--or the transmission of acquired characters--is one of the most important principles in evolutionary science. Unless we admit it most of the facts of comparative anatomy and physiology are inexplicable. That was the conviction of Darwin no less than of Lamarck, of Spencer as well as Virchow, of Huxley as well as Gegenbaur, indeed of the great majority of speculative biologists. This fundamental principle was for the first time called in question and assailed in 1885 by August Weismann of Freiburg, the eminent zoologist to whom the theory of evolution owes a great deal of valuable support, and who has attained distinction by his extension of the theory of selection. In explanation of the phenomena of heredity he introduced a new theory, the "theory of the continuity of the germ-plasm." According to him the living substance in all organisms consists of two quite distinct kinds of plasm, somatic and germinal. The permanent germ-plasm, or the active substance of the two germ-cells (egg-cell and sperm-cell), passes unchanged through a series of generations, and is not affected by environmental influences. The environment modifies only the soma-plasm, the organs and tissues of the body. The modifications that these parts undergo through the influence of the environment or their own activity (use and habit), do not affect the germ-plasm, and cannot therefore be transmitted. This theory of the continuity of the germ-plasm has been expounded by Weismann during the last twenty-four years in a number of able volumes, and is regarded by many biologists, such as Mr Francis Galton, Sir E. Ray Lankester, and Professor J. Arthur Thomson (who has recently made a thoroughgoing defence of it in his important work "Heredity" (London, 1908.)), as the most striking advance in evolutionary science. On the other hand, the theory has been rejected by Herbert Spencer, Sir W. Turner, Gegenbaur, Kolliker, Hertwig, and many others. For my part I have, with all respect for the distinguished Darwinian, contested the theory from the first, because its whole foundation seems to me erroneous, and its deductions do not seem to be in accord with the main facts of comparative morphology and physiology. Weismann's theory in its entirety is a finely conceived molecular hypothesis, but it is devoid of empirical basis. The notion of the absolute and permanent independence of the germ-plasm, as distinguished from the soma-plasm, is purely speculative; as is also the theory of germinal selection. The determinants, ids, and idants, are purely hypothetical elements. The experiments that have been devised to demonstrate their existence really prove nothing. It seems to me quite improper to describe this hypothetical structure as "Neodarwinism." Darwin was just as convinced as Lamarck of the transmission of acquired characters and its great importance in the scheme of evolution. I had the good fortune to visit Darwin at Down three times and discuss with him the main principles of his system, and on each occasion we were fully agreed as to the incalculable importance of what I call transformative inheritance. It is only proper to point out that Weismann's theory of the germ-plasm is in express contradiction to the fundamental principles of Darwin and Lamarck. Nor is it more acceptable in what one may call its "ultradarwinism"--the idea that the theory of selection explains everything in the evolution of the organic world. This belief in the "omnipotence of natural selection" was not shared by Darwin himself. Assuredly, I regard it as of the utmost value, as the process of natural selection through the struggle for life affords an explanation of the mechanical origin of the adapted organisation. It solves the great problem: how could the finely adapted structure of the animal or plant body be formed unless it was built on a preconceived plan? It thus enables us to dispense with the teleology of the metaphysician and the dualist, and to set aside the old mythological and poetic legends of creation. The idea had occurred in vague form to the great Empedocles 2000 years before the time of Darwin, but it was reserved for modern research to give it ample expression. Nevertheless, natural selection does not of itself give the solution of all our evolutionary problems. It has to be taken in conjunction with the transformism of Lamarck, with which it is in complete harmony. The monumental greatness of Charles Darwin, who surpasses every other student of science in the nineteenth century by the loftiness of his monistic conception of nature and the progressive influence of his ideas, is perhaps best seen in the fact that not one of his many successors has succeeded in modifying his theory of descent in any essential point or in discovering an entirely new standpoint in the interpretation of the organic world. Neither Nageli nor Weismann, neither De Vries nor Roux, has done this. Nageli, in his "Mechanisch-Physiologische Theorie der Abstammungslehre" (Munich, 1884.), which is to a great extent in agreement with Weismann, constructed a theory of the idioplasm, that represents it (like the germ-plasm) as developing continuously in a definite direction from internal causes. But his internal "principle of progress" is at the bottom just as teleological as the vital force of the Vitalists, and the micellar structure of the idioplasm is just as hypothetical as the "dominant" structure of the germ-plasm. In 1889 Moritz Wagner sought to explain the origin of species by migration and isolation, and on that basis constructed a special "migration-theory." This, however, is not out of harmony with the theory of selection. It merely elevates one single factor in the theory to a predominant position. Isolation is only a special case of selection, as I had pointed out in the fifteenth chapter of my "Natural history of creation". The "mutation-theory" of De Vries ("Die Mutationstheorie", Leipzig, 1903.), that would explain the origin of species by sudden and saltatory variations rather than by gradual modification, is regarded by many botanists as a great step in advance, but it is generally rejected by zoologists. It affords no explanation of the facts of adaptation, and has no causal value. Much more important than these theories is that of Wilhelm Roux ("Der Kampf der Theile im Organismus", Leipzig, 1881.) of "the struggle of parts within the organism, a supplementation of the theory of mechanical adaptation." He explains the functional autoformation of the purposive structure by a combination of Darwin's principle of selection with Lamarck's idea of transformative heredity, and applies the two in conjunction to the facts of histology. He lays stress on the significance of functional adaptation, which I had described in 1866, under the head of cumulative adaptation, as the most important factor in evolution. Pointing out its influence in the cell-life of the tissues, he puts "cellular selection" above "personal selection," and shows how the finest conceivable adaptations in the structure of the tissue may be brought about quite mechanically, without preconceived plan. This "mechanical teleology" is a valuable extension of Darwin's monistic principle of selection to the whole field of cellular physiology and histology, and is wholly destructive of dualistic vitalism. The most important advance that evolution has made since Darwin and the most valuable amplification of his theory of selection is, in my opinion, the work of Richard Semon: "Die Mneme als erhaltendes Prinzip im Wechsel des organischen Geschehens" (Leipzig, 1904.). He offers a psychological explanation of the facts of heredity by reducing them to a process of (unconscious) memory. The physiologist Ewald Hering had shown in 1870 that memory must be regarded as a general function of organic matter, and that we are quite unable to explain the chief vital phenomena, especially those of reproduction and inheritance, unless we admit this unconscious memory. In my essay "Die Perigenesis der Plastidule" (Berlin, 1876.) I elaborated this far-reaching idea, and applied the physical principle of transmitted motion to the plastidules, or active molecules of plasm. I concluded that "heredity is the memory of the plastidules, and variability their power of comprehension." This "provisional attempt to give a mechanical explanation of the elementary processes of evolution" I afterwards extended by showing that sensitiveness is (as Carl Nageli, Ernst Mach, and Albrecht Rau express it) a general quality of matter. This form of panpsychism finds its simplest expression in the "trinity of substance." To the two fundamental attributes that Spinoza ascribed to substance--Extension (matter as occupying space) and Cogitation (energy, force)--we now add the third fundamental quality of Psychoma (sensitiveness, soul). I further elaborated this trinitarian conception of substance in the nineteenth chapter of my "Die Lebenswunder" (1904) ("Wonders of Life", London, 1904.), and it seems to me well calculated to afford a monistic solution of many of the antitheses of philosophy. This important Mneme-theory of Semon and the luminous physiological experiments and observations associated with it not only throw considerable light on transformative inheritance, but provide a sound physiological foundation for the biogenetic law. I had endeavoured to show in 1874, in the first chapter of my "Anthropogenie" (English translation; "The Evolution of Man", 2 volumes, London, 1879 and 1905.), that this fundamental law of organic evolution holds good generally, and that there is everywhere a direct causal connection between ontogeny and phylogeny. "Phylogenesis is the mechanical cause of ontogenesis"; in other words, "The evolution of the stem or race is--in accordance with the laws of heredity and adaptation--the real cause of all the changes that appear, in a condensed form, in the development of the individual organism from the ovum, in either the embryo or the larva." It is now fifty years since Charles Darwin pointed out, in the thirteenth chapter of his epoch-making "Origin of Species", the fundamental importance of embryology in connection with his theory of descent: "The leading facts in embryology, which are second to none in importance, are explained on the principle of variations in the many descendants from some one ancient progenitor, having appeared at a not very early period of life, and having been inherited at a corresponding period." ("Origin of Species" (6th edition), page 396.) He then shows that the striking resemblance of the embryos and larvae of closely related animals, which in the mature stage belong to widely different species and genera, can only be explained by their descent from a common progenitor. Fritz Muller made a closer study of these important phenomena in the instructive instance of the Crustacean larva, as given in his able work "Fur Darwin" (1864). (English translation; "Facts and Arguments for Darwin", London, 1869.) I then, in 1872, extended the range so as to include all animals (with the exception of the unicellular Protozoa) and showed, by means of the theory of the Gastraea, that all multicellular, tissue-forming animals--all the Metazoa--develop in essentially the same way from the primary germ-layers. I conceived the embryonic form, in which the whole structure consists of only two layers of cells, and is known as the gastrula, to be the ontogenetic recapitulation, maintained by tenacious heredity, of a primitive common progenitor of all the Metazoa, the Gastraea. At a later date (1895) Monticelli discovered that this conjectural ancestral form is still preserved in certain primitive Coelenterata--Pemmatodiscus, Kunstleria, and the nearly-related Orthonectida. The general application of the biogenetic law to all classes of animals and plants has been proved in my "Systematische Phylogenie". (3 volumes, Berlin, 1894-96.) It has, however, been frequently challenged, both by botanists and zoologists, chiefly owing to the fact that many have failed to distinguish its two essential elements, palingenesis and cenogenesis. As early as 1874 I had emphasised, in the first chapter of my "Evolution of Man", the importance of discriminating carefully between these two sets of phenomena: "In the evolutionary appreciation of the facts of embryology we must take particular care to distinguish sharply and clearly between the primary, palingenetic evolutionary processes and the secondary, cenogenetic processes. The palingenetic phenomena, or embryonic RECAPITULATIONS, are due to heredity, to the transmission of characters from one generation to another. They enable us to draw direct inferences in regard to corresponding structures in the development of the species (e.g. the chorda or the branchial arches in all vertebrate embryos). The cenogenetic phenomena, on the other hand, or the embryonic VARIATIONS, cannot be traced to inheritance from a mature ancestor, but are due to the adaptation of the embryo or the larva to certain conditions of its individual development (e.g. the amnion, the allantois, and the vitelline arteries in the embryos of the higher vertebrates). These cenogenetic phenomena are later additions; we must not infer from them that there were corresponding processes in the ancestral history, and hence they are apt to mislead." The fundamental importance of these facts of comparative anatomy, atavism, and the rudimentary organs, was pointed out by Darwin in the first part of his classic work, "The Descent of Man and Selection in Relation to Sex" (1871). ("Descent of Man" (Popular Edition), page 927.) In the "General summary and conclusion" (chapter XXI.) he was able to say, with perfect justice: "He who is not content to look, like a savage, at the phenomena of nature as disconnected, cannot any longer believe that man is the work of a separate act of creation. He will be forced to admit that the close resemblance of the embryo of man to that, for instance, of a dog--the construction of his skull, limbs, and whole frame on the same plan with that of other mammals, independently of the uses to which the parts may be put--the occasional reappearance of various structures, for instance of several muscles, which man does not normally possess, but which are common to the Quadrumana--and a crowd of analogous facts--all point in the plainest manner to the conclusion that man is the co-descendant with other mammals of a common progenitor." These few lines of Darwin's have a greater scientific value than hundreds of those so-called "anthropological treatises," which give detailed descriptions of single organs, or mathematical tables with series of numbers and what are claimed to be "exact analyses," but are devoid of synoptic conclusions and a philosophical spirit. Charles Darwin is not generally recognised as a great anthropologist, nor does the school of modern anthropologists regard him as a leading authority. In Germany, especially, the great majority of the members of the anthropological societies took up an attitude of hostility to him from the very beginning of the controversy in 1860. "The Descent of Man" was not merely rejected, but even the discussion of it was forbidden on the ground that it was "unscientific." The centre of this inveterate hostility for thirty years--especially after 1877--was Rudolph Virchow of Berlin, the leading investigator in pathological anatomy, who did so much for the reform of medicine by his establishment of cellular pathology in 1858. As a prominent representative of "exact" or "descriptive" anthropology, and lacking a broad equipment in comparative anatomy and ontogeny, he was unable to accept the theory of descent. In earlier years, and especially during his splendid period of activity at Wurzburg (1848-1856), he had been a consistent free-thinker, and had in a number of able articles (collected in his "Gesammelte Abhandlungen") ("Gesammelte Abhandlungen zur wissenschaftlichen Medizin", Berlin, 1856.) upheld the unity of human nature, the inseparability of body and spirit. In later years at Berlin, where he was more occupied with political work and sociology (especially after 1866), he abandoned the positive monistic position for one of agnosticism and scepticism, and made concessions to the dualistic dogma of a spiritual world apart from the material frame. In the course of a Scientific Congress at Munich in 1877 the conflict of these antithetic views of nature came into sharp relief. At this memorable Congress I had undertaken to deliver the first address (September 18th) on the subject of "Modern evolution in relation to the whole of science." I maintained that Darwin's theory not only solved the great problem of the origin of species, but that its implications, especially in regard to the nature of man, threw considerable light on the whole of science, and on anthropology in particular. The discovery of the real origin of man by evolution from a long series of mammal ancestors threw light on his place in nature in every aspect, as Huxley had already shown in his excellent lectures of 1863. Just as all the organs and tissues of the human body had originated from those of the nearest related mammals, certain ape-like forms, so we were bound to conclude that his mental qualities also had been derived from those of his extinct primate ancestor. This monistic view of the origin and nature of man, which is now admitted by nearly all who have the requisite acquaintance with biology, and approach the subject without prejudice, encountered a sharp opposition at that time. The opposition found its strongest expression in an address that Virchow delivered at Munich four days afterwards (September 22nd), on "The freedom of science in the modern State." He spoke of the theory of evolution as an unproved hypothesis, and declared that it ought not to be taught in the schools, because it was dangerous to the State. "We must not," he said, "teach that man has descended from the ape or any other animal." When Darwin, usually so lenient in his judgment, read the English translation of Virchow's speech, he expressed his disapproval in strong terms. But the great authority that Virchow had--an authority well founded in pathology and sociology--and his prestige as President of the German Anthropological Society, had the effect of preventing any member of the Society from raising serious opposition to him for thirty years. Numbers of journals and treatises repeated his dogmatic statement: "It is quite certain that man has descended neither from the ape nor from any other animal." In this he persisted till his death in 1902. Since that time the whole position of German anthropology has changed. The question is no longer whether man was created by a distinct supernatural act or evolved from other mammals, but to which line of the animal hierarchy we must look for the actual series of ancestors. The interested reader will find an account of this "battle of Munich" (1877) in my three Berlin lectures (April, 1905) ("Der Kampf um die Entwickelungs-Gedanken". (English translation; "Last Words on Evolution", London, 1906.)) The main points in our genealogical tree were clearly recognised by Darwin in the sixth chapter of the "Descent of Man". Lowly organised fishes, like the lancelet (Amphioxus), are descended from lower invertebrates resembling the larvae of an existing Tunicate (Appendicularia). From these primitive fishes were evolved higher fishes of the ganoid type and others of the type of Lepidosiren (Dipneusta). It is a very small step from these to the Amphibia: "In the class of mammals the steps are not difficult to conceive which led from the ancient Monotremata to the ancient Marsupials; and from these to the early progenitors of the placental mammals. We may thus ascend to the Lemuridae; and the interval is not very wide from these to the Simiadae. The Simiadae then branched off into two great stems, the New World and Old World monkeys; and from the latter, at a remote period, Man, the wonder and glory of the Universe, proceeded." ("Descent of Man" (Popular Edition), page 255.) In these few lines Darwin clearly indicated the way in which we were to conceive our ancestral series within the vertebrates. It is fully confirmed by all the arguments of comparative anatomy and embryology, of palaeontology and physiology; and all the research of the subsequent forty years has gone to establish it. The deep interest in geology which Darwin maintained throughout his life and his complete knowledge of palaeontology enabled him to grasp the fundamental importance of the palaeontological record more clearly than anthropologists and zoologists usually do. There has been much debate in subsequent decades whether Darwin himself maintained that man was descended from the ape, and many writers have sought to deny it. But the lines I have quoted verbatim from the conclusion of the sixth chapter of the "Descent of Man" (1871) leave no doubt that he was as firmly convinced of it as was his great precursor Jean Lamarck in 1809. Moreover, Darwin adds, with particular explicitness, in the "general summary and conclusion" (chapter XXI.) of that standard work ("Descent of Man", page 930.): "By considering the embryological structure of man--the homologies which he presents with the lower animals,--the rudiments which he retains,--and the reversions to which he is liable, we can partly recall in imagination the former condition of our early progenitors; and can approximately place them in their proper place in the zoological series. We thus learn that man is descended from a hairy, tailed quadruped, probably arboreal in its habits, and an inhabitant of the Old World. This creature, if its whole structure had been examined by a naturalist, would have been classed amongst the Quadrumana, as surely as the still more ancient progenitor of the Old and New World monkeys." These clear and definite lines leave no doubt that Darwin--so critical and cautious in regard to important conclusions--was quite as firmly convinced of the descent of man from the apes (the Catarrhinae, in particular) as Lamarck was in 1809 and Huxley in 1863. It is to be noted particularly that, in these and other observations on the subject, Darwin decidedly assumes the monophyletic origin of the mammals, including man. It is my own conviction that this is of the greatest importance. A number of difficult questions in regard to the development of man, in respect of anatomy, physiology, psychology, and embryology, are easily settled if we do not merely extend our progonotaxis to our nearest relatives, the anthropoid apes and the tailed monkeys from which these have descended, but go further back and find an ancestor in the group of the Lemuridae, and still further back to the Marsupials and Monotremata. The essential identity of all the Mammals in point of anatomical structure and embryonic development--in spite of their astonishing differences in external appearance and habits of life--is so palpably significant that modern zoologists are agreed in the hypothesis that they have all sprung from a common root, and that this root may be sought in the earlier Palaeozoic Amphibia. The fundamental importance of this comparative morphology of the Mammals, as a sound basis of scientific anthropology, was recognised just before the beginning of the nineteenth century, when Lamarck first emphasised (1794) the division of the animal kingdom into Vertebrates and Invertebrates. Even thirteen years earlier (1781), when Goethe made a close study of the mammal skeleton in the Anatomical Institute at Jena, he was intensely interested to find that the composition of the skull was the same in man as in the other mammals. His discovery of the os intermaxillare in man (1784), which was contradicted by most of the anatomists of the time, and his ingenious "vertebral theory of the skull," were the splendid fruit of his morphological studies. They remind us how Germany's greatest philosopher and poet was for many years ardently absorbed in the comparative anatomy of man and the mammals, and how he divined that their wonderful identity in structure was no mere superficial resemblance, but pointed to a deep internal connection. In my "Generelle Morphologie" (1866), in which I published the first attempts to construct phylogenetic trees, I have given a number of remarkable theses of Goethe, which may be called "phyletic prophecies." They justify us in regarding him as a precursor of Darwin. In the ensuing forty years I have made many conscientious efforts to penetrate further along that line of anthropological research that was opened up by Goethe, Lamarck, and Darwin. I have brought together the many valuable results that have constantly been reached in comparative anatomy, physiology, ontogeny, and palaeontology, and maintained the effort to reform the classification of animals and plants in an evolutionary sense. The first rough drafts of pedigrees that were published in the "Generelle Morphologie" have been improved time after time in the ten editions of my "Naturaliche Schopfungsgeschichte" (1868-1902). (English translation; "The History of Creation", London, 1876.) A sounder basis for my phyletic hypotheses, derived from a discriminating combination of the three great records--morphology, ontogeny, and palaeontology--was provided in the three volumes of my "Systematische Phylogenie" (Berlin, 1894-96.) (1894 Protists and Plants, 1895 Vertebrates, 1896 Invertebrates). In my "Anthropogenie" (Leipzig, 1874, 5th edition 1905. English translation; "The Evolution of Man", London, 1905.) I endeavoured to employ all the known facts of comparative ontogeny (embryology) for the purpose of completing my scheme of human phylogeny (evolution). I attempted to sketch the historical development of each organ of the body, beginning with the most elementary structures in the germ-layers of the Gastraea. At the same time I drew up a corrected statement of the most important steps in the line of our ancestral series. At the fourth International Congress of Zoology at Cambridge (August 26th, 1898) I delivered an address on "Our present knowledge of the Descent of Man." It was translated into English, enriched with many valuable notes and additions, by my friend and pupil in earlier days Dr Hans Gadow (Cambridge), and published under the title: "The Last Link; our present knowledge of the Descent of Man". (London, 1898.) The determination of the chief animal forms that occur in the line of our ancestry is there restricted to thirty types, and these are distributed in six main groups. The first half of this "Progonotaxis hominis," which has no support from fossil evidence, comprises three groups: (i) Protista (unicellular organisms, 1-5: (ii) Invertebrate Metazoa (Coelenteria 6-8, Vermalia 9-11): (iii) Monorrhine Vertebrates (Acrania 12-13, Cyclostoma 14-15). The second half, which is based on fossil records, also comprises three groups: (iv) Palaeozoic cold-blooded Craniota (Fishes 16-18, Amphibia 19, Reptiles 20: (v) Mesozoic Mammals (Monotrema 21, Marsupialia 22, Mallotheria 23): (vi) Cenozoic Primates (Lemuridae 24-25, Tailed Apes 26-27, Anthropomorpha 28-30). An improved and enlarged edition of this hypothetic "Progonotaxis hominis" was published in 1908, in my essay "Unsere Ahnenreihe". ("Festschrift zur 350-jahrigen Jubelfeier der Thuringer Universitat Jena". Jena, 1908.) If I have succeeded in furthering, in some degree, by these anthropological works, the solution of the great problem of Man's place in nature, and particularly in helping to trace the definite stages in our ancestral series, I owe the success, not merely to the vast progress that biology has made in the last half century, but largely to the luminous example of the great investigators who have applied themselves to the problem, with so much assiduity and genius, for a century and a quarter--I mean Goethe and Lamarck, Gegenbaur and Huxley, but, above all, Charles Darwin. It was the great genius of Darwin that first brought together the scattered material of biology and shaped it into that symmetrical temple of scientific knowledge, the theory of descent. It was Darwin who put the crown on the edifice by his theory of natural selection. Not until this broad inductive law was firmly established was it possible to vindicate the special conclusion, the descent of man from a series of other Vertebrates. By his illuminating discovery Darwin did more for anthropology than thousands of those writers, who are more specifically titled anthropologists, have done by their technical treatises. We may, indeed, say that it is not merely as an exact observer and ingenious experimenter, but as a distinguished anthropologist and far-seeing thinker, that Darwin takes his place among the greatest men of science of the nineteenth century. To appreciate fully the immortal merit of Darwin in connection with anthropology, we must remember that not only did his chief work, "The Origin of Species", which opened up a new era in natural history in 1859, sustain the most virulent and widespread opposition for a lengthy period, but even thirty years later, when its principles were generally recognised and adopted, the application of them to man was energetically contested by many high scientific authorities. Even Alfred Russel Wallace, who discovered the principle of natural selection independently in 1858, did not concede that it was applicable to the higher mental and moral qualities of man. Dr Wallace still holds a spiritualist and dualist view of the nature of man, contending that he is composed of a material frame (descended from the apes) and an immortal immaterial soul (infused by a higher power). This dual conception, moreover, is still predominant in the wide circles of modern theology and metaphysics, and has the general and influential adherence of the more conservative classes of society. In strict contradiction to this mystical dualism, which is generally connected with teleology and vitalism, Darwin always maintained the complete unity of human nature, and showed convincingly that the psychological side of man was developed, in the same way as the body, from the less advanced soul of the anthropoid ape, and, at a still more remote period, from the cerebral functions of the older vertebrates. The eighth chapter of the "Origin of Species", which is devoted to instinct, contains weighty evidence that the instincts of animals are subject, like all other vital processes, to the general laws of historic development. The special instincts of particular species were formed by adaptation, and the modifications thus acquired were handed on to posterity by heredity; in their formation and preservation natural selection plays the same part as in the transformation of every other physiological function. The higher moral qualities of civilised man have been derived from the lower mental functions of the uncultivated barbarians and savages, and these in turn from the social instincts of the mammals. This natural and monistic psychology of Darwin's was afterwards more fully developed by his friend George Romanes in his excellent works "Mental Evolution in Animals" and "Mental Evolution in Man". (London, 1885; 1888.) Many valuable and most interesting contributions to this monistic psychology of man were made by Darwin in his fine work on "The Descent of Man and Selection in Relation to Sex", and again in his supplementary work, "The Expression of the Emotions in Man and Animals". To understand the historical development of Darwin's anthropology one must read his life and the introduction to "The Descent of Man". From the moment that he was convinced of the truth of the principle of descent--that is to say, from his thirtieth year, in 1838--he recognised clearly that man could not be excluded from its range. He recognised as a logical necessity the important conclusion that "man is the co-descendant with other species of some ancient, lower, and extinct form." For many years he gathered notes and arguments in support of this thesis, and for the purpose of showing the probable line of man's ancestry. But in the first edition of "The Origin of Species" (1859) he restricted himself to the single line, that by this work "light would be thrown on the origin of man and his history." In the fifty years that have elapsed since that time the science of the origin and nature of man has made astonishing progress, and we are now fairly agreed in a monistic conception of nature that regards the whole universe, including man, as a wonderful unity, governed by unalterable and eternal laws. In my philosophical book "Die Weltratsel" (1899) ("The Riddle of the Universe", London, 1900.) and in the supplementary volume "Die Lebenswunder" (1904) "The Wonders of Life", London, (1904.), I have endeavoured to show that this pure monism is securely established, and that the admission of the all-powerful rule of the same principle of evolution throughout the universe compels us to formulate a single supreme law--the all-embracing "Law of Substance," or the united laws of the constancy of matter and the conservation of energy. We should never have reached this supreme general conception if Charles Darwin--a "monistic philosopher" in the true sense of the word--had not prepared the way by his theory of descent by natural selection, and crowned the great work of his life by the association of this theory with a naturalistic anthropology. IX. SOME PRIMITIVE THEORIES OF THE ORIGIN OF MAN. By J.G. FRAZER. Fellow of Trinity College, Cambridge. On a bright day in late autumn a good many years ago I had ascended the hill of Panopeus in Phocis to examine the ancient Greek fortifications which crest its brow. It was the first of November, but the weather was very hot; and when my work among the ruins was done, I was glad to rest under the shade of a clump of fine holly-oaks, to inhale the sweet refreshing perfume of the wild thyme which scented all the air, and to enjoy the distant prospects, rich in natural beauty, rich too in memories of the legendary and historic past. To the south the finely-cut peak of Helicon peered over the low intervening hills. In the west loomed the mighty mass of Parnassus, its middle slopes darkened by pine-woods like shadows of clouds brooding on the mountain-side; while at its skirts nestled the ivy-mantled walls of Daulis overhanging the deep glen, whose romantic beauty accords so well with the loves and sorrows of Procne and Philomela, which Greek tradition associated with the spot. Northwards, across the broad plain to which the hill of Panopeus descends, steep and bare, the eye rested on the gap in the hills through which the Cephissus winds his tortuous way to flow under grey willows, at the foot of barren stony hills, till his turbid waters lose themselves, no longer in the vast reedy swamps of the now vanished Copaic Lake, but in the darkness of a cavern in the limestone rock. Eastward, clinging to the slopes of the bleak range of which the hill of Panopeus forms part, were the ruins of Chaeronea, the birthplace of Plutarch; and out there in the plain was fought the disastrous battle which laid Greece at the feet of Macedonia. There, too, in a later age East and West met in deadly conflict, when the Roman armies under Sulla defeated the Asiatic hosts of Mithridates. Such was the landscape spread out before me on one of those farewell autumn days of almost pathetic splendour, when the departing summer seems to linger fondly, as if loth to resign to winter the enchanted mountains of Greece. Next day the scene had changed: summer was gone. A grey November mist hung low on the hills which only yesterday had shone resplendent in the sun, and under its melancholy curtain the dead flat of the Chaeronean plain, a wide treeless expanse shut in by desolate slopes, wore an aspect of chilly sadness befitting the battlefield where a nation's freedom was lost. But crowded as the prospect from Panopeus is with memories of the past, the place itself, now so still and deserted, was once the scene of an event even more ancient and memorable, if Greek story-tellers can be trusted. For here, they say, the sage Prometheus created our first parents by fashioning them, like a potter, out of clay. (Pausanias X. 4.4. Compare Apollodorus, "Bibliotheca", I. 7. 1; Ovid, "Metamorph." I. 82 sq.; Juvenal, "Sat". XIV. 35. According to another version of the tale, this creation of mankind took place not at Panopeus, but at Iconium in Lycaonia. After the original race of mankind had been destroyed in the great flood of Deucalion, the Greek Noah, Zeus commanded Prometheus and Athena to create men afresh by moulding images out of clay, breathing the winds into them, and making them live. See "Etymologicum Magnum", s.v. "'Ikonion", pages 470 sq. It is said that Prometheus fashioned the animals as well as men, giving to each kind of beast its proper nature. See Philemon, quoted by Stobaeus, "Florilegium" II. 27. The creation of man by Prometheus is figured on ancient works of art. See J. Toutain, "Etudes de Mythologie et d'Histoire des Religions Antiques" (Paris, 1909), page 190. According to Hesiod ("Works and Days", 60 sqq.) it was Hephaestus who at the bidding of Zeus moulded the first woman out of moist earth.) The very spot where he did so can still be seen. It is a forlorn little glen or rather hollow behind the hill of Panopeus, below the ruined but still stately walls and towers which crown the grey rocks of the summit. The glen, when I visited it that hot day after the long drought of summer, was quite dry; no water trickled down its bushy sides, but in the bottom I found a reddish crumbling earth, a relic perhaps of the clay out of which the potter Prometheus moulded the Greek Adam and Eve. In a volume dedicated to the honour of one who has done more than any other in modern times to shape the ideas of mankind as to their origin it may not be out of place to recall this crude Greek notion of the creation of the human race, and to compare or contrast it with other rudimentary speculations of primitive peoples on the same subject, if only for the sake of marking the interval which divides the childhood from the maturity of science. The simple notion that the first man and woman were modelled out of clay by a god or other superhuman being is found in the traditions of many peoples. This is the Hebrew belief recorded in Genesis: "The Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul." (Genesis ii.7.) To the Hebrews this derivation of our species suggested itself all the more naturally because in their language the word for "ground" (adamah) is in form the feminine of the word for man (adam). (S.R. Driver and W.H.Bennett, in their commentaries on Genesis ii. 7.) From various allusions in Babylonian literature it would seem that the Babylonians also conceived man to have been moulded out of clay. (H. Zimmern, in E. Schrader's "Die Keilinschriften und das Alte Testament" 3 (Berlin, 1902), page 506.) According to Berosus, the Babylonian priest whose account of creation has been preserved in a Greek version, the god Bel cut off his own head, and the other gods caught the flowing blood, mixed it with earth, and fashioned men out of the bloody paste; and that, they said, is why men are so wise, because their mortal clay is tempered with divine blood. (Eusebius, "Chronicon", ed. A. Schoene, Vol. I. (Berlin, 1875), col. 16.) In Egyptian mythology Khnoumou, the Father of the gods, is said to have moulded men out of clay. (G. Maspero, "Histoire Ancienne des Peuples de l'Orient Classique", I. (Paris, 1895), page 128.) We cannot doubt that such crude conceptions of the origin of our race were handed down to the civilised peoples of antiquity by their savage or barbarous forefathers. Certainly stories of the same sort are known to be current among savages and barbarians. Thus the Australian blacks in the neighbourhood of Melbourne said that Pund-jel, the creator, cut three large sheets of bark with his big knife. On one of these he placed some clay and worked it up with his knife into a proper consistence. He then laid a portion of the clay on one of the other pieces of bark and shaped it into a human form; first he made the feet, then the legs, then the trunk, the arms, and the head. Thus he made a clay man on each of the two pieces of bark; and being well pleased with them he danced round them for joy. Next he took stringy bark from the Eucalyptus tree, made hair of it, and stuck it on the heads of his clay men. Then he looked at them again, was pleased with his work, and again danced round them for joy. He then lay down on them, blew his breath hard into their mouths, their noses, and their navels; and presently they stirred, spoke, and rose up as full-grown men. (R. Brough Smyth, "The Aborigines of Victoria" (Melbourne, 1878), I. 424. This and many of the following legends of creation have been already cited by me in a note on Pausanias X. 4. 4 ("Pausanias's Description of Greece, translated with a Commentary" (London, 1898), Vol V. pages 220 sq.).) The Maoris of New Zealand say that Tiki made man after his own image. He took red clay, kneaded it, like the Babylonian Bel, with his own blood, fashioned it in human form, and gave the image breath. As he had made man in his own likeness he called him Tiki-ahua or Tiki's likeness. (R. Taylor "Te Ika A Maui, or New Zealand and its Inhabitants", Second Edition (London, 1870), page 117. Compare E. Shortland, "Maori Religion and Mythology" (London, 1882), pages 21 sq.) A very generally received tradition in Tahiti was that the first human pair was made by Taaroa, the chief god. They say that after he had formed the world he created man out of red earth, which was also the food of mankind until bread-fruit was produced. Further, some say that one day Taaroa called for the man by name, and when he came he made him fall asleep. As he slept, the creator took out one of his bones (ivi) and made a woman of it, whom he gave to the man to be his wife, and the pair became the progenitors of mankind. This narrative was taken down from the lips of the natives in the early years of the mission to Tahiti. The missionary who records it observes: "This always appeared to me a mere recital of the Mosaic account of creation, which they had heard from some European, and I never placed any reliance on it, although they have repeatedly told me it was a tradition among them before any foreigner arrived. Some have also stated that the woman's name was Ivi, which would be by them pronounced as if written "Eve". "Ivi" is an aboriginal word, and not only signifies a bone, but also a widow, and a victim slain in war. Notwithstanding the assertion of the natives, I am disposed to think that "Ivi", or Eve, is the only aboriginal part of the story, as far as it respects the mother of the human race. (W. Ellis, "Polynesian Researches", Second Edition (London, 1832), I. 110 sq. "Ivi" or "iwi" is the regular word for "bone" in the various Polynesian languages. See E. Tregear, "The Maori-Polynesian Comparative Dictionary" (Wellington, New Zealand, 1891), page 109.) However, the same tradition has been recorded in other parts of Polynesia besides Tahiti. Thus the natives of Fakaofo or Bowditch Island say that the first man was produced out of a stone. After a time he bethought him of making a woman. So he gathered earth and moulded the figure of a woman out of it, and having done so he took a rib out of his left side and thrust it into the earthen figure, which thereupon started up a live woman. He called her Ivi (Eevee) or "rib" and took her to wife, and the whole human race sprang from this pair. (G. Turner, "Samoa" (London, 1884), pages 267 sq.) The Maoris also are reported to believe that the first woman was made out of the first man's ribs. (J.L. Nicholas, "Narrative of a Voyage to New Zealand" (London, 1817), I. 59, who writes "and to add still more to this strange coincidence, the general term for bone is 'Hevee'.") This wide diffusion of the story in Polynesia raises a doubt whether it is merely, as Ellis thought, a repetition of the Biblical narrative learned from Europeans. In Nui, or Netherland Island, it was the god Aulialia who made earthen models of a man and woman, raised them up, and made them live. He called the man Tepapa and the woman Tetata. (G. Turner, "Samoa", pages 300 sq.) In the Pelew Islands they say that a brother and sister made men out of clay kneaded with the blood of various animals, and that the characters of these first men and of their descendants were determined by the characters of the animals whose blood had been kneaded with the primordial clay; for instance, men who have rat's blood in them are thieves, men who have serpent's blood in them are sneaks, and men who have cock's blood in them are brave. (J. Kubary, "Die Religion der Pelauer", in A. Bastian's "Allerlei aus Volks- und Menschenkunde" (Berlin, 1888), I. 3, 56.) According to a Melanesian legend, told in Mota, one of the Banks Islands, the hero Qat moulded men of clay, the red clay from the marshy river-side at Vanua Lava. At first he made men and pigs just alike, but his brothers remonstrated with him, so he beat down the pigs to go on all fours and made men walk upright. Qat fashioned the first woman out of supple twigs, and when she smiled he knew she was a living woman. (R.H. Codrington, "The Melanesians" (Oxford, 1891), page 158.) A somewhat different version of the Melanesian story is told at Lakona, in Santa Maria. There they say that Qat and another spirit ("vui") called Marawa both made men. Qat made them out of the wood of dracaena-trees. Six days he worked at them, carving their limbs and fitting them together. Then he allowed them six days to come to life. Three days he hid them away, and three days more he worked to make them live. He set them up and danced to them and beat his drum, and little by little they stirred, till at last they could stand all by themselves. Then Qat divided them into pairs and called each pair husband and wife. Marawa also made men out of a tree, but it was a different tree, the tavisoviso. He likewise worked at them six days, beat his drum, and made them live, just as Qat did. But when he saw them move, he dug a pit and buried them in it for six days, and then, when he scraped away the earth to see what they were doing, he found them all rotten and stinking. That was the origin of death. (R.H. Codrington op. cit., pages 157 sq.) The inhabitants of Noo-Hoo-roa, in the Kei Islands say that their ancestors were fashioned out of clay by the supreme god, Dooadlera, who breathed life into the clay figures. (C.M. Pleyte, "Ethnographische Beschrijving der Kei-Eilanden", "Tijdschrift van het Nederlandsch Aardrijkskundig Genootschap", Tweede Serie X. (1893), page 564.) The aborigines of Minahassa, in the north of Celebes, say that two beings called Wailan Wangko and Wangi were alone on an island, on which grew a cocoa-nut tree. Said Wailan Wangko to Wangi, "Remain on earth while I climb up the tree." Said Wangi to Wailan Wangko, "Good." But then a thought occurred to Wangi and he climbed up the tree to ask Wailan Wangko why he, Wangi, should remain down there all alone. Said Wailan Wangko to Wangi, "Return and take earth and make two images, a man and a woman." Wangi did so, and both images were men who could move but could not speak. So Wangi climbed up the tree to ask Wailan Wangko, "How now? The two images are made, but they cannot speak." Said Wailan Wangko to Wangi, "Take this ginger and go and blow it on the skulls and the ears of these two images, that they may be able to speak; call the man Adam and the woman Ewa." (N. Graafland "De Minahassa" (Rotterdam, 1869), I. pages 96 sq.) In this narrative the names of the man and woman betray European influence, but the rest of the story may be aboriginal. The Dyaks of Sakarran in British Borneo say that the first man was made by two large birds. At first they tried to make men out of trees, but in vain. Then they hewed them out of rocks, but the figures could not speak. Then they moulded a man out of damp earth and infused into his veins the red gum of the kumpang-tree. After that they called to him and he answered; they cut him and blood flowed from his wounds. (Horsburgh, quoted by H. Ling Roth, "The Natives of Sarawak and of British North Borneo" (London, 1896), I. pages 299 sq. Compare The Lord Bishop of Labuan, "On the Wild Tribes of the North-West Coast of Borneo," "Transactions of the Ethnological Society of London", New Series, II. (1863), page 27.) The Kumis of South-Eastern India related to Captain Lewin, the Deputy Commissioner of Hill Tracts, the following tradition of the creation of man. "God made the world and the trees and the creeping things first, and after that he set to work to make one man and one woman, forming their bodies of clay; but each night, on the completion of his work, there came a great snake, which, while God was sleeping, devoured the two images. This happened twice or thrice, and God was at his wit's end, for he had to work all day, and could not finish the pair in less than twelve hours; besides, if he did not sleep, he would be no good," said Captain Lewin's informant. "If he were not obliged to sleep, there would be no death, nor would mankind be afflicted with illness. It is when he rests that the snake carries us off to this day. Well, he was at his wit's end, so at last he got up early one morning and first made a dog and put life into it, and that night, when he had finished the images, he set the dog to watch them, and when the snake came, the dog barked and frightened it away. This is the reason at this day that when a man is dying the dogs begin to howl; but I suppose God sleeps heavily now-a-days, or the snake is bolder, for men die all the same." (Capt. T.H. Lewin, "Wild Races of South-Eastern India" (London, 1870), pages 224-26.) The Khasis of Assam tell a similar tale. (A. Bastian, "Volkerstamme am Brahmaputra und verwandtschaftliche Nachbarn" (Berlin, 1883), page 8; Major P.R.T. Gurdon, "The Khasis" (London, 1907), page 106.) The Ewe-speaking tribes of Togo-land, in West Africa, think that God still makes men out of clay. When a little of the water with which he moistens the clay remains over, he pours it on the ground and out of that he makes the bad and disobedient people. When he wishes to make a good man he makes him out of good clay; but when he wishes to make a bad man, he employs only bad clay for the purpose. In the beginning God fashioned a man and set him on the earth; after that he fashioned a woman. The two looked at each other and began to laugh, whereupon God sent them into the world. (J. Spieth, "Die Ewe-Stamme, Material zur Kunde des Ewe-Volkes in Deutsch-Togo" (Berlin, 1906), pages 828, 840.) The Innuit or Esquimaux of Point Barrow, in Alaska, tell of a time when there was no man in the land, till a spirit named "a se lu", who resided at Point Barrow, made a clay man, set him up on the shore to dry, breathed into him and gave him life. ("Report of the International Expedition to Point Barrow" (Washington, 1885), page 47.) Other Esquimaux of Alaska relate how the Raven made the first woman out of clay to be a companion to the first man; he fastened water-grass to the back of the head to be hair, flapped his wings over the clay figure, and it arose, a beautiful young woman. (E.W. Nelson, "The Eskimo about Bering Strait", "Eighteenth Annual Report of the Bureau of American Ethnology", Part I. (Washington, 1899), page 454.) The Acagchemem Indians of California said that a powerful being called Chinigchinich created man out of clay which he found on the banks of a lake; male and female created he them, and the Indians of the present day are their descendants. (Friar Geronimo Boscana, "Chinigchinich", appended to (A. Robinson's) "Life in California" (New York, 1846), page 247.) A priest of the Natchez Indians in Louisiana told Du Pratz "that God had kneaded some clay, such as that which potters use and had made it into a little man; and that after examining it, and finding it well formed, he blew up his work, and forthwith that little man had life, grew, acted, walked, and found himself a man perfectly well shaped." As to the mode in which the first woman was created, the priest had no information, but thought she was probably made in the same way as the first man; so Du Pratz corrected his imperfect notions by reference to Scripture. (M. Le Page Du Pratz, "The History of Louisiana" (London, 1774), page 330.) The Michoacans of Mexico said that the great god Tucapacha first made man and woman out of clay, but that when the couple went to bathe in a river they absorbed so much water that the clay of which they were composed all fell to pieces. Then the creator went to work again and moulded them afresh out of ashes, and after that he essayed a third time and made them of metal. This last attempt succeeded. The metal man and woman bathed in the river without falling to pieces, and by their union they became the progenitors of mankind. (A. de Herrera, "General History of the vast Continent and Islands of America", translated into English by Capt. J. Stevens (London, 1725, 1726), III. 254; Brasseur de Bourbourg, "Histoire des Nations Civilisees du Mexique et de l'Amerique-Centrale" (Paris, 1857--1859), III. 80 sq; compare id. I. 54 sq.) According to a legend of the Peruvian Indians, which was told to a Spanish priest in Cuzco about half a century after the conquest, it was in Tiahuanaco that man was first created, or at least was created afresh after the deluge. "There (in Tiahuanaco)," so runs the legend, "the Creator began to raise up the people and nations that are in that region, making one of each nation of clay, and painting the dresses that each one was to wear; those that were to wear their hair, with hair, and those that were to be shorn, with hair cut. And to each nation was given the language, that was to be spoken, and the songs to be sung, and the seeds and food that they were to sow. When the Creator had finished painting and making the said nations and figures of clay, he gave life and soul to each one, as well men as women, and ordered that they should pass under the earth. Thence each nation came up in the places to which he ordered them to go." (E.J. Payne, "History of the New World called America", I. (Oxford, 1892), page 462.) These examples suffice to prove that the theory of the creation of man out of dust or clay has been current among savages in many parts of the world. But it is by no means the only explanation which the savage philosopher has given of the beginnings of human life on earth. Struck by the resemblances which may be traced between himself and the beasts, he has often supposed, like Darwin himself, that mankind has been developed out of lower forms of animal life. For the simple savage has none of that high notion of the transcendant dignity of man which makes so many superior persons shrink with horror from the suggestion that they are distant cousins of the brutes. He on the contrary is not too proud to own his humble relations; indeed his difficulty often is to perceive the distinction between him and them. Questioned by a missionary, a Bushman of more than average intelligence "could not state any difference between a man and a brute--he did not know but a buffalo might shoot with bows and arrows as well as man, if it had them." (Reverend John Campbell, "Travels in South Africa" (London, 1822, II. page 34.) When the Russians first landed on one of the Alaskan islands, the natives took them for cuttle-fish "on account of the buttons on their clothes." (I. Petroff, "Report on the Population, Industries, and Resources of Alaska", page 145.) The Giliaks of the Amoor think that the outward form and size of an animal are only apparent; in substance every beast is a real man, just like a Giliak himself, only endowed with an intelligence and strength, which often surpass those of mere ordinary human beings. (L. Sternberg, "Die Religion der Giljaken", "Archiv fur Religionswissenschaft", VIII. (1905), page 248.) The Borororos, an Indian tribe of Brazil, will have it that they are parrots of a gorgeous red plumage which live in their native forests. Accordingly they treat the birds as their fellow-tribesmen, keeping them in captivity, refusing to eat their flesh, and mourning for them when they die. (K. von den Steinen, "Unter den Naturvolkern Zentral-Brasiliens" (Berlin, 1894), pages 352 sq., 512.)) This sense of the close relationship of man to the lower creation is the essence of totemism, that curious system of superstition which unites by a mystic bond a group of human kinsfolk to a species of animals or plants. Where that system exists in full force, the members of a totem clan identify themselves with their totem animals in a way and to an extent which we find it hard even to imagine. For example, men of the Cassowary clan in Mabuiag think that cassowaries are men or nearly so. "Cassowary, he all same as relation, he belong same family," is the account they give of their relationship with the long-legged bird. Conversely they hold that they themselves are cassowaries for all practical purposes. They pride themselves on having long thin legs like a cassowary. This reflection affords them peculiar satisfaction when they go out to fight, or to run away, as the case may be; for at such times a Cassowary man will say to himself, "My leg is long and thin, I can run and not feel tired; my legs will go quickly and the grass will not entangle them." Members of the Cassowary clan are reputed to be pugnacious, because the cassowary is a bird of very uncertain temper and can kick with extreme violence. (A.C. Haddon, "The Ethnography of the Western Tribe of Torres Straits", "Journal of the Anthropological Institute", XIX. (1890), page 393; "Reports of the Cambridge Anthropological Expedition to Torres Straits", V. (Cambridge, 1904), pages 166, 184.) So among the Ojibways men of the Bear clan are reputed to be surly and pugnacious like bears, and men of the Crane clan to have clear ringing voices like cranes. (W.W. Warren, "History of the Ojibways", "Collections of the Minnesota Historical Society", V. (Saint Paul, Minn. 1885), pages 47, 49.) Hence the savage will often speak of his totem animal as his father or his brother, and will neither kill it himself nor allow others to do so, if he can help it. For example, if somebody were to kill a bird in the presence of a native Australian who had the bird for his totem, the black might say, "What for you kill that fellow? that my father!" or "That brother belonging to me you have killed; why did you do it?" (E. Palmer, "Notes on some Australian Tribes", "Journal of the Anthropological Institute", XIII. (1884), page 300.) Bechuanas of the Porcupine clan are greatly afflicted if anybody hurts or kills a porcupine in their presence. They say, "They have killed our brother, our master, one of ourselves, him whom we sing of"; and so saying they piously gather the quills of their murdered brother, spit on them, and rub their eyebrows with them. They think they would die if they touched its flesh. In like manner Bechuanas of the Crocodile clan call the crocodile one of themselves, their master, their brother; and they mark the ears of their cattle with a long slit like a crocodile's mouth by way of a family crest. Similarly Bechuanas of the Lion clan would not, like the members of other clans, partake of lion's flesh; for how, say they, could they eat their grandfather? If they are forced in self-defence to kill a lion, they do so with great regret and rub their eyes carefully with its skin, fearing to lose their sight if they neglected this precaution. (T. Arbousset et F. Daumas, "Relation d'un Voyage d'Exploration au Nord-Est de la Colonie du Cap de Bonne-Esperance" (Paris, 1842), pages 349 sq., 422-24.) A Mandingo porter has been known to offer the whole of his month's pay to save the life of a python, because the python was his totem and he therefore regarded the reptile as his relation; he thought that if he allowed the creature to be killed, the whole of his own family would perish, probably through the vengeance to be taken by the reptile kinsfolk of the murdered serpent. (M. le Docteur Tautain, "Notes sur les Croyances et Pratiques Religieuses des Banmanas", "Revue d'Ethnographie", III. (1885), pages 396 sq.; A. Rancon, "Dans la Haute-Gambie, Voyage d'Exploration Scientifique" (Paris, 1894), page 445.) Sometimes, indeed, the savage goes further and identifies the revered animal not merely with a kinsman but with himself; he imagines that one of his own more or less numerous souls, or at all events that a vital part of himself, is in the beast, so that if it is killed he must die. Thus, the Balong tribe of the Cameroons, in West Africa, think that every man has several souls, of which one is lodged in an elephant, a wild boar, a leopard, or what not. When any one comes home, feels ill, and says, "I shall soon die," and is as good as his word, his friends are of opinion that one of his souls has been shot by a hunter in a wild boar or a leopard, for example, and that that is the real cause of his death. (J. Keller, "Ueber das Land und Volk der Balong", "Deutsches Kolonialblatt", 1 October, 1895, page 484.) A Catholic missionary, sleeping in the hut of a chief of the Fan negroes, awoke in the middle of the night to see a huge black serpent of the most dangerous sort in the act of darting at him. He was about to shoot it when the chief stopped him, saying, "In killing that serpent, it is me that you would have killed. Fear nothing, the serpent is my elangela." (Father Trilles, "Chez les Fang, leurs Moeurs, leur Langue, leur Religion", "Les Missions Catholiques", XXX. (1898), page 322.) At Calabar there used to be some years ago a huge old crocodile which was well known to contain the spirit of a chief who resided in the flesh at Duke Town. Sporting Vice-Consuls, with a reckless disregard of human life, from time to time made determined attempts to injure the animal, and once a peculiarly active officer succeeded in hitting it. The chief was immediately laid up with a wound in his leg. He SAID that a dog had bitten him, but few people perhaps were deceived by so flimsy a pretext. (Miss Mary H. Kingsley, "Travels in West Africa" (London, 1897), pages 538 sq. As to the external or bush souls of human beings, which in this part of Africa are supposed to be lodged in the bodies of animals, see Miss Mary H. Kingsley op. cit. pages 459-461; R. Henshaw, "Notes on the Efik belief in 'bush soul'", "Man", VI.(1906), pages 121 sq.; J. Parkinson, "Notes on the Asaba people (Ibos) of the Niger", "Journal of the Anthropological Institute", XXXVI. (1906), pages 314 sq.) Once when Mr Partridge's canoe-men were about to catch fish near an Assiga town in Southern Nigeria, the natives of the town objected, saying, "Our souls live in those fish, and if you kill them we shall die." (Charles Partridge, "Cross River Natives" (London, 1905), pages 225 sq.) On another occasion, in the same region, an Englishman shot a hippopotamus near a native village. The same night a woman died in the village, and her friends demanded and obtained from the marksman five pounds as compensation for the murder of the woman, whose soul or second self had been in that hippopotamus. (C.H. Robinson, "Hausaland" (London, 1896), pages 36 sq.) Similarly at Ndolo, in the Congo region, we hear of a chief whose life was bound up with a hippopotamus, but he prudently suffered no one to fire at the animal. ("Notes Analytiques sur les Collections Ethnographiques du Musee du Congo", I. (Brussels, 1902-06), page 150.) Amongst people who thus fail to perceive any sharp line of distinction between beasts and men it is not surprising to meet with the belief that human beings are directly descended from animals. Such a belief is often found among totemic tribes who imagine that their ancestors sprang from their totemic animals or plants; but it is by no means confined to them. Thus, to take instances, some of the Californian Indians, in whose mythology the coyote or prairie-wolf is a leading personage, think that they are descended from coyotes. At first they walked on all fours; then they began to have some members of the human body, one finger, one toe, one eye, one ear, and so on; then they got two fingers, two toes, two eyes, two ears, and so forth; till at last, progressing from period to period, they became perfect human beings. The loss of their tails, which they still deplore, was produced by the habit of sitting upright. (H.R. Schoolcraft, "Indian Tribes of the United States", IV. (Philadelphia, 1856), pages 224 sq.; compare id. V. page 217. The descent of some, not all, Indians from coyotes is mentioned also by Friar Boscana, in (A. Robinson's) "Life in California" (New York, 1846), page 299.) Similarly Darwin thought that "the tail has disappeared in man and the anthropomorphous apes, owing to the terminal portion having been injured by friction during a long lapse of time; the basal and embedded portion having been reduced and modified, so as to become suitable to the erect or semi-erect position." (Charles Darwin, "The Descent of Man", Second Edition (London, 1879), page 60.) The Turtle clam of the Iroquois think that they are descended from real mud turtles which used to live in a pool. One hot summer the pool dried up, and the mud turtles set out to find another. A very fat turtle, waddling after the rest in the heat, was much incommoded by the weight of his shell, till by a great effort he heaved it off altogether. After that he gradually developed into a man and became the progenitor of the Turtle clan. (E.A. Smith, "Myths of the Iroquois", "Second Annual Report of the Bureau of Ethnology" (Washington, 1883), page 77.) The Crawfish band of the Choctaws are in like manner descended from real crawfish, which used to live under ground, only coming up occasionally through the mud to the surface. Once a party of Choctaws smoked them out, taught them the Choctaw language, taught them to walk on two legs, made them cut off their toe nails and pluck the hair from their bodies, after which they adopted them into the tribe. But the rest of their kindred, the crawfish, are crawfish under ground to this day. (Geo. Catlin, "North American Indians" 4 (London, 1844), II. page 128.) The Osage Indians universally believed that they were descended from a male snail and a female beaver. A flood swept the snail down to the Missouri and left him high and dry on the bank, where the sun ripened him into a man. He met and married a beaver maid, and from the pair the tribe of the Osages is descended. For a long time these Indians retained a pious reverence for their animal ancestors and refrained from hunting beavers, because in killing a beaver they killed a brother of the Osages. But when white men came among them and offered high prices for beaver skins, the Osages yielded to the temptation and took the lives of their furry brethren. (Lewis and Clarke, "Travels to the Source of the Missouri River" (London, 1815), I. 12 (Vol. I. pages 44 sq. of the London reprint, 1905).) The Carp clan of the Ootawak Indians are descended from the eggs of a carp which had been deposited by the fish on the banks of a stream and warmed by the sun. ("Lettres Edifiantes et Curieuses", Nouvelle Edition, VI. (Paris, 1781), page 171.) The Crane clan of the Ojibways are sprung originally from a pair of cranes, which after long wanderings settled on the rapids at the outlet of Lake Superior, where they were changed by the Great Spirit into a man and woman. (L.H. Morgan, "Ancient Society" (London, 1877), page 180.) The members of two Omaha clans were originally buffaloes and lived, oddly enough, under water, which they splashed about, making it muddy. And at death all the members of these clans went back to their ancestors the buffaloes. So when one of them lay adying, his friends used to wrap him up in a buffalo skin with the hair outside and say to him, "You came hither from the animals and you are going back thither. Do not face this way again. When you go, continue walking. (J. Owen Dorsey, "Omaha Sociology", "Third Annual Report of the Bureau of Ethnology" (Washington, 1884), pages 229, 233.) The Haida Indians of Queen Charlotte Islands believe that long ago the raven, who is the chief figure in the mythology of North-West America, took a cockle from the beach and married it; the cockle gave birth to a female child, whom the raven took to wife, and from their union the Indians were produced. (G.M. Dawson, "Report on the Queen Charlotte Islands" (Montreal, 1880), pages 149B sq. ("Geological Survey of Canada"); F. Poole, "Queen Charlotte Islands", page 136.) The Delaware Indians called the rattle-snake their grandfather and would on no account destroy one of these reptiles, believing that were they to do so the whole race of rattle-snakes would rise up and bite them. Under the influence of the white man, however, their respect for their grandfather the rattle-snake gradually died away, till at last they killed him without compunction or ceremony whenever they met him. The writer who records the old custom observes that he had often reflected on the curious connection which appears to subsist in the mind of an Indian between man and the brute creation; "all animated nature," says he, "in whatever degree, is in their eyes a great whole, from which they have not yet ventured to separate themselves." (Rev. John Heckewelder, "An Account of the History, Manners, and Customs, of the Indian Nations, who once inhabited Pennsylvania and the Neighbouring States", "Transactions of the Historical and Literary Committee of the American Philosophical Society", I. (Philadelphia, 1819), pages 245, 247, 248.) Some of the Indians of Peru boasted of being descended from the puma or American lion; hence they adored the lion as a god and appeared at festivals like Hercules dressed in the skins of lions with the heads of the beasts fixed over their own. Others claimed to be sprung from condors and attired themselves in great black and white wings, like that enormous bird. (Garcilasso de la Vega, "First Part of the Royal Commentaries of the Yncas", Vol. I. page 323, Vol. II. page 156 (Markham's translation).) The Wanika of East Africa look upon the hyaena as one of their ancestors or as associated in some way with their origin and destiny. The death of a hyaena is mourned by the whole people, and the greatest funeral ceremonies which they perform are performed for this brute. The wake held over a chief is as nothing compared to the wake held over a hyaena; one tribe only mourns the death of its chief, but all the tribes unite to celebrate the obsequies of a hyaena. (Charles New, "Life, Wanderings, and Labours in Eastern Africa" (London, 1873) page 122.) Some Malagasy families claim to be descended from the babacoote (Lichanotus brevicaudatus), a large lemur of grave appearance and staid demeanour, which lives in the depth of the forest. When they find one of these creatures dead, his human descendants bury it solemnly, digging a grave for it, wrapping it in a shroud, and weeping and lamenting over its carcase. A doctor who had shot a babacoote was accused by the inhabitants of a Betsimisaraka village of having killed "one of their grandfathers in the forest," and to appease their indignation he had to promise not to skin the animal in the village but in a solitary place where nobody could see him. (Father Abinal, "Croyances fabuleuses des Malgaches", "Les Missions Catholiques", XII. (1880), page 526; G.H. Smith, "Some Betsimisaraka superstitions", "The Antananarivo Annual and Madagascar Magazine", No. 10 (Antananarivo, 1886), page 239; H.W. Little, "Madagascar, its History and People" (London, 1884), pages 321 sq; A. van Gennep, "Tabou et Totemisme a Madagascar" (Paris, 1904), pages 214 sqq.) Many of the Betsimisaraka believe that the curious nocturnal animal called the aye-aye (Cheiromys madagascariensis) "is the embodiment of their forefathers, and hence will not touch it, much less do it an injury. It is said that when one is discovered dead in the forest, these people make a tomb for it and bury it with all the forms of a funeral. They think that if they attempt to entrap it, they will surely die in consequence." (G.A. Shaw, "The Aye-aye", "Antananarivo Annual and Madagascar Magazine", Vol. II. (Antananarivo, 1896), pages 201, 203 (Reprint of the Second four Numbers). Compare A. van Gennep, "Tabou et Totemisme a Madagascar", pages 223 sq.) Some Malagasy tribes believe themselves descended from crocodiles and accordingly they deem the formidable reptiles their brothers. If one of these scaly brothers so far forgets the ties of kinship as to devour a man, the chief of the tribe, or in his absence an old man familiar with the tribal customs, repairs at the head of the people to the edge of the water, and summons the family of the culprit to deliver him up to the arm of justice. A hook is then baited and cast into the river or lake. Next day the guilty brother or one of his family is dragged ashore, formally tried, sentenced to death, and executed. The claims of justice being thus satisfied, the dead animal is lamented and buried like a kinsman; a mound is raised over his grave and a stone marks the place of his head. (Father Abinal, "Croyances fabuleuses des Malgaches", "Les Missions Catholiques", XII. (1880), page 527; A. van Gennep, "Tabou et Totemisme a Madagascar", pages 281 sq.) Amongst the Tshi-speaking tribes of the Gold Coast in West Africa the Horse-mackerel family traces its descent from a real horse-mackerel whom an ancestor of theirs once took to wife. She lived with him happily in human shape on shore till one day a second wife, whom the man had married, cruelly taunted her with being nothing but a fish. That hurt her so much that bidding her husband farewell she returned to her old home in the sea, with her youngest child in her arms, and never came back again. But ever since the Horse-mackerel people have refrained from eating horse-mackerels, because the lost wife and mother was a fish of that sort. (A.B. Ellis, "The Tshi-speaking Peoples of the Gold Coast of West Africa" (London, 1887), pages 208-11. A similar tale is told by another fish family who abstain from eating the fish (appei) from which they take their name (A.B. Ellis op. cit. pages 211 sq.).) Some of the Land Dyaks of Borneo tell a similar tale to explain a similar custom. "There is a fish which is taken in their rivers called a puttin, which they would on no account touch, under the idea that if they did they would be eating their relations. The tradition respecting it is, that a solitary old man went out fishing and caught a puttin, which he dragged out of the water and laid down in his boat. On turning round, he found it had changed into a very pretty little girl. Conceiving the idea she would make, what he had long wished for, a charming wife for his son, he took her home and educated her until she was fit to be married. She consented to be the son's wife cautioning her husband to use her well. Some time after their marriage, however, being out of temper, he struck her, when she screamed, and rushed away into the water; but not without leaving behind her a beautiful daughter, who became afterwards the mother of the race." (The Lord Bishop of Labuan, "On the Wild Tribes of the North-West Coast of Borneo", "Transactions of the Ethnological Society of London", New Series II. (London, 1863), pages 26 sq. Such stories conform to a well-known type which may be called the Swan-Maiden type of story, or Beauty and the Beast, or Cupid and Psyche. The occurrence of stories of this type among totemic peoples, such as the Tshi-speaking negroes of the Gold Coast, who tell them to explain their totemic taboos, suggests that all such tales may have originated in totemism. I shall deal with this question elsewhere.) Members of a clan in Mandailing, on the west coast of Sumatra, assert that they are descended from a tiger, and at the present day, when a tiger is shot, the women of the clan are bound to offer betel to the dead beast. When members of this clan come upon the tracks of a tiger, they must, as a mark of homage, enclose them with three little sticks. Further, it is believed that the tiger will not attack or lacerate his kinsmen, the members of the clan. (H. Ris, "De Onderafdeeling Klein Mandailing Oeloe en Pahantan en hare Bevolking met uitzondering van de Oeloes", "Bijdragen tot de Tall- Land- en Volkenkunde van Nederlansch-Indie, XLVI." (1896), page 473.) The Battas of Central Sumatra are divided into a number of clans which have for their totems white buffaloes, goats, wild turtle-doves, dogs, cats, apes, tigers, and so forth; and one of the explanations which they give of their totems is that these creatures were their ancestors, and that their own souls after death can transmigrate into the animals. (J.B. Neumann, "Het Pane en Bila-stroomgebied op het eiland Sumatra", "Tijdschrift van het Nederlandsch Aardrijkskundig Genootschap", Tweede Serie, III. Afdeeling, Meer uitgebreide Artikelen, No. 2 (Amsterdam, 1886), pages 311 sq.; id. ib. Tweede Serie, IV. Afdeeling, Meer uitgebreide Artikelen, No. 1 (Amsterdam, 1887), pages 8 sq.) In Amboyna and the neighbouring islands the inhabitants of some villages aver that they are descended from trees, such as the Capellenia moluccana, which had been fertilised by the Pandion Haliaetus. Others claim to be sprung from pigs, octopuses, crocodiles, sharks, and eels. People will not burn the wood of the trees from which they trace their descent, nor eat the flesh of the animals which they regard as their ancestors. Sicknesses of all sorts are believed to result from disregarding these taboos. (J.G.F. Riedel, "De sluik- en kroesharige rassen tusschen Selebes en Papua" (The Hague, 1886), pages 32, 61; G.W.W.C. Baron van Hoevell, "Ambon en meer bepaaldelijk de Oeliasers" (Dordrecht, 1875), page 152.) Similarly in Ceram persons who think they are descended from crocodiles, serpents, iguanas, and sharks will not eat the flesh of these animals. (J.G.F. Riedel op. cit. page 122.) Many other peoples of the Molucca Islands entertain similar beliefs and observe similar taboos. (J.G.F. Riedel "De sluik- en kroesharige rassen tusschen Selebes en Papua" (The Hague, 1886), pages 253, 334, 341, 348, 412, 414, 432.) Again, in Ponape, one of the Caroline Islands, "The different families suppose themselves to stand in a certain relation to animals, and especially to fishes, and believe in their descent from them. They actually name these animals 'mothers'; the creatures are sacred to the family and may not be injured. Great dances, accompanied with the offering of prayers, are performed in their honour. Any person who killed such an animal would expose himself to contempt and punishment, certainly also to the vengeance of the insulted deity." Blindness is commonly supposed to be the consequence of such a sacrilege. (Dr Hahl, "Mittheilungen uber Sitten und rechtliche Verhaltnisse auf Ponape", "Ethnologisches Notizblatt", Vol. II. Heft 2 (Berlin, 1901), page 10.) Some of the aborigines of Western Australia believe that their ancestors were swans, ducks, or various other species of water-fowl before they were transformed into men. (Captain G. Grey, "A Vocabulary of the Dialects of South Western Australia", Second Edition (London, 1840), pages 29, 37, 61, 63, 66, 71.) The Dieri tribe of Central Australia, who are divided into totemic clans, explain their origin by the following legend. They say that in the beginning the earth opened in the midst of Perigundi Lake, and the totems (murdus or madas) came trooping out one after the other. Out came the crow, and the shell parakeet, and the emu, and all the rest. Being as yet imperfectly formed and without members or organs of sense, they laid themselves down on the sandhills which surrounded the lake then just as they do now. It was a bright day and the totems lay basking in the sunshine, till at last, refreshed and invigorated by it, they stood up as human beings and dispersed in all directions. That is why people of the same totem are now scattered all over the country. You may still see the island in the lake out of which the totems came trooping long ago. (A.W. Howitt, "Native Tribes of South-East Australia" (London, 1904), pages 476, 779 sq.) Another Dieri legend relates how Paralina, one of the Mura-Muras or mythical predecessors of the Dieri, perfected mankind. He was out hunting kangaroos, when he saw four incomplete beings cowering together. So he went up to them, smoothed their bodies, stretched out their limbs, slit up their fingers and toes, formed their mouths, noses, and eyes, stuck ears on them, and blew into their ears in order that they might hear. Having perfected their organs and so produced mankind out of these rudimentary beings, he went about making men everywhere. (A.W. Howitt op. cit., pages 476, 780 sq.) Yet another Dieri tradition sets forth how the Mura-Mura produced the race of man out of a species of small black lizards, which may still be met with under dry bark. To do this he divided the feet of the lizards into fingers and toes, and, applying his forefinger to the middle of their faces, created a nose; likewise he gave them human eyes, mouths and ears. He next set one of them upright, but it fell down again because of its tail; so he cut off its tail and the lizard then walked on its hind legs. That is the origin of mankind. (S. Gason, "The Manners and Customs of the Dieyerie tribe of Australian Aborigines", "Native Tribes of South Australia" (Adelaide, 1879), page 260. This writer fell into the mistake of regarding the Mura-Mura (Mooramoora) as a Good-Spirit instead of as one of the mythical but more or less human predecessors of the Dieri in the country. See A.W. Howitt, "Native Tribes of South-East Australia", pages 475 sqq.) The Arunta tribe of Central Australia similarly tell how in the beginning mankind was developed out of various rudimentary forms of animal life. They say that in those days two beings called Ungambikula, that is, "out of nothing," or "self-existing," dwelt in the western sky. From their lofty abode they could see, far away to the east, a number of inapertwa creatures, that is, rudimentary human beings or incomplete men, whom it was their mission to make into real men and women. For at that time there were no real men and women; the rudimentary creatures (inapertwa) were of various shapes and dwelt in groups along the shore of the salt water which covered the country. These embryos, as we may call them, had no distinct limbs or organs of sight, hearing, and smell; they did not eat food, and they presented the appearance of human beings all doubled up into a rounded mass, in which only the outline of the different parts of the body could be vaguely perceived. Coming down from their home in the western sky, armed with great stone knives, the Ungambikula took hold of the embryos, one after the other. First of all they released the arms from the bodies, then making four clefts at the end of each arm they fashioned hands and fingers; afterwards legs, feet, and toes were added in the same way. The figure could now stand; a nose was then moulded and the nostrils bored with the fingers. A cut with the knife made the mouth, which was pulled open several times to render it flexible. A slit on each side of the face separated the upper and lower eye-lids, disclosing the eyes, which already existed behind them; and a few strokes more completed the body. Thus out of the rudimentary creatures were formed men and women. These rudimentary creatures or embryos, we are told, "were in reality stages in the transformation of various animals and plants into human beings, and thus they were naturally, when made into human beings, intimately associated with the particular animal or plant, as the case may be, of which they were the transformations--in other words, each individual of necessity belonged to a totem, the name of which was of course that of the animal or plant of which he or she was a transformation." However, it is not said that all the totemic clans of the Arunta were thus developed; no such tradition, for example, is told to explain the origin of the important Witchetty Grub clan. The clans which are positively known, or at least said, to have originated out of embryos in the way described are the Plum Tree, the Grass Seed, the Large Lizard, the Small Lizard, the Alexandra Parakeet, and the Small Rat clans. When the Ungambikula had thus fashioned people of these totems, they circumcised them all, except the Plum Tree men, by means of a fire-stick. After that, having done the work of creation or evolution, the Ungambikula turned themselves into little lizards which bear a name meaning "snappers-up of flies." (Baldwin Spencer and F.J. Gillen, "Native Tribes of Central Australia" (London, 1899), pages 388 sq.; compare id., "Northern Tribes of Central Australia" (London, 1904), page 150.) This Arunta tradition of the origin of man, as Messrs Spencer and Gillen, who have recorded it, justly observe, "is of considerable interest; it is in the first place evidently a crude attempt to describe the origin of human beings out of non-human creatures who were of various forms; some of them were representatives of animals, others of plants, but in all cases they are to be regarded as intermediate stages in the transition of an animal or plant ancestor into a human individual who bore its name as that of his or her totem." (Baldwin Spencer and F.J. Gillen, "Native Tribes of Central Australia", pages 391 sq.) In a sense these speculations of the Arunta on their own origin may be said to combine the theory of creation with the theory of evolution; for while they represent men as developed out of much simpler forms of life, they at the same time assume that this development was effected by the agency of two powerful beings, whom so far we may call creators. It is well known that at a far higher stage of culture a crude form of the evolutionary hypothesis was propounded by the Greek philosopher Empedocles. He imagined that shapeless lumps of earth and water, thrown up by the subterranean fires, developed into monstrous animals, bulls with the heads of men, men with the heads of bulls, and so forth; till at last, these hybrid forms being gradually eliminated, the various existing species of animals and men were evolved. (E. Zeller, "Die Philosophie der Griechen", I.4 (Leipsic, 1876), pages 718 sq.; H. Ritter et L. Preller, "Historia Philosophiae Graecae et Romanae ex fontium locis contexta" 5, pages 102 sq. H. Diels, "Die Fragmente der Vorsokratiker" 2, I. (Berlin, 1906), pages 190 sqq. Compare Lucretius "De rerum natura", V. 837 sqq.) The theory of the civilised Greek of Sicily may be set beside the similar theory of the savage Arunta of Central Australia. Both represent gropings of the human mind in the dark abyss of the past; both were in a measure grotesque anticipations of the modern theory of evolution. In this essay I have made no attempt to illustrate all the many various and divergent views which primitive man has taken of his own origin. I have confined myself to collecting examples of two radically different views, which may be distinguished as the theory of creation and the theory of evolution. According to the one, man was fashioned in his existing shape by a god or other powerful being; according to the other he was evolved by a natural process out of lower forms of animal life. Roughly speaking, these two theories still divide the civilised world between them. The partisans of each can appeal in support of their view to a large consensus of opinion; and if truth were to be decided by weighing the one consensus against the other, with "Genesis" in the one scale and "The Origin of Species" in the other, it might perhaps be found, when the scales were finally trimmed, that the balance hung very even between creation and evolution. X. THE INFLUENCE OF DARWIN ON THE STUDY OF ANIMAL EMBRYOLOGY. By A. Sedgwick, M.A., F.R.S. Professor of Zoology and Comparative Anatomy in the University of Cambridge. The publication of "The Origin of Species" ushered in a new era in the study of Embryology. Whereas, before the year 1859 the facts of anatomy and development were loosely held together by the theory of types, which owed its origin to the great anatomists of the preceding generation, to Cuvier, L. Agassiz, J. Muller, and R. Owen, they were now combined together into one organic whole by the theory of descent and by the hypothesis of recapitulation which was deduced from that theory. The view (First clearly enunciated by Fritz Muller in his well-known work, "Fur Darwin", Leipzig, 1864; (English Edition, "Facts for Darwin", 1869).) that a knowledge of embryonic and larval histories would lay bare the secrets of race-history and enable the course of evolution to be traced, and so lead to the discovery of the natural system of classification, gave a powerful stimulus to morphological study in general and to embryological investigation in particular. In Darwin's words: "Embryology rises greatly in interest, when we look at the embryo as a picture, more or less obscured, of the progenitor, either in its adult or larval state, of all the members of the same great class." ("Origin" (6th edition), page 396.) In the period under consideration the output of embryological work has been enormous. No group of the animal kingdom has escaped exhaustive examination and no effort has been spared to obtain the embryos of isolated and out of the way forms, the development of which might have an important bearing upon questions of phylogeny and classification. Marine zoological stations have been established, expeditions have been sent to distant countries, and the methods of investigation have been greatly improved. The result of this activity has been that the main features of the developmental history of all the most important animals are now known and the curiosity as to developmental processes, so greatly excited by the promulgation of the Darwinian theory, has to a considerable extent been satisfied. To what extent have the results of this vast activity fulfilled the expectations of the workers who have achieved them? The Darwin centenary is a fitting moment at which to take stock of our position. In this inquiry we shall leave out of consideration the immense and intensely interesting additions to our knowledge of Natural History. These may be said to constitute a capital fund upon which philosophers, poets and men of science will draw for many generations. The interest of Natural History existed long before Darwinian evolution was thought of and will endure without any reference to philosophic speculations. She is a mistress in whose face are beauties and in whose arms are delights elsewhere unattainable. She is and always has been pursued for her own sake without any reference to philosophy, science, or utility. Darwin's own views of the bearing of the facts of embryology upon questions of wide scientific interest are perfectly clear. He writes ("Origin" (6th edition), page 395.): "On the other hand it is highly probable that with many animals the embryonic or larval stages show us, more or less completely, the condition of the progenitor of the whole group in its adult state. In the great class of the Crustacea, forms wonderfully distinct from each other, namely, suctorial parasites, cirripedes, entomostraca, and even the malacostraca, appear at first as larvae under the nauplius-form; and as these larvae live and feed in the open sea, and are not adapted for any peculiar habits of life, and from other reasons assigned by Fritz Muller, it is probable that at some very remote period an independent adult animal, resembling the Nauplius, existed, and subsequently produced, along several divergent lines of descent, the above-named great Crustacean groups. So again it is probable, from what we know of the embryos of mammals, birds, fishes, and reptiles, that these animals are the modified descendants of some ancient progenitor, which was furnished in its adult state with branchiae, a swim-bladder, four fin-like limbs, and a long tail, all fitted for an aquatic life. "As all the organic beings, extinct and recent, which have ever lived, can be arranged within a few great classes; and as all within each class have, according to our theory, been connected together by fine gradations, the best, and, if our collections were nearly perfect, the only possible arrangement, would be genealogical; descent being the hidden bond of connexion which naturalists have been seeking under the term of the Natural System. On this view we can understand how it is that, in the eyes of most naturalists, the structure of the embryo is even more important for classification than that of the adult. In two or more groups of animals, however much they may differ from each other in structure and habits in their adult condition, if they pass through closely similar embryonic stages, we may feel assured that they all are descended from one parent-form, and are therefore closely related. Thus, community in embryonic structure reveals community of descent; but dissimilarity in embryonic development does not prove discommunity of descent, for in one of two groups the developmental stages may have been suppressed, or may have been so greatly modified through adaptation to new habits of life, as to be no longer recognisable. Even in groups, in which the adults have been modified to an extreme degree, community of origin is often revealed by the structure of the larvae; we have seen, for instance, that cirripedes, though externally so like shell-fish, are at once known by their larvae to belong to the great class of crustaceans. As the embryo often shows us more or less plainly the structure of the less modified and ancient progenitor of the group, we can see why ancient and extinct forms so often resemble in their adult state the embryos of existing species of the same class. Agassiz believes this to be a universal law of nature; and we may hope hereafter to see the law proved true. It can, however, be proved true only in those cases in which the ancient state of the progenitor of the group has not been wholly obliterated, either by successive variations having supervened at a very early period of growth, or by such variations having been inherited at an earlier stage than that at which they first appeared. It should also be borne in mind, that the law may be true, but yet, owing to the geological record not extending far enough back in time, may remain for a long period, or for ever, incapable of demonstration. The law will not strictly hold good in those cases in which an ancient form became adapted in its larval state to some special line of life, and transmitted the same larval state to a whole group of descendants; for such larvae will not resemble any still more ancient form in its adult state." As this passage shows, Darwin held that embryology was of interest because of the light it seems to throw upon ancestral history (phylogeny) and because of the help it would give in enabling us to arrive at a natural system of classification. With regard to the latter point, he quotes with approval the opinion that "the structure of the embryo is even more important for classification than that of the adult." What justification is there for this view? The phase of life chosen for the ordinary anatomical and physiological studies, namely, the adult phase, is merely one of the large number of stages of structure through which the organism passes. By far the greater number of these are included in what is specially called the developmental or (if we include larvae with embryos) embryonic period, for the developmental changes are more numerous and take place with greater rapidity at the beginning of life than in its later periods. As each of these stages is equal in value, for our present purpose, to the adult phase, it clearly follows that if there is anything in the view that the anatomical study of organisms is of importance in determining their mutual relations, the study of the organism in its various embryonic (and larval) stages must have a greater importance than the study of the single and arbitrarily selected stage of life called the adult. But a deeper reason than this has been assigned for the importance of embryology in classification. It has been asserted, and is implied by Darwin in the passage quoted, that the ancestral history is repeated in a condensed form in the embryonic, and that a study of the latter enables us to form a picture of the stages of structure through which the organism has passed in its evolution. It enables us on this view to reconstruct the pedigrees of animals and so to form a genealogical tree which shall be the true expression of their natural relations. The real question which we have to consider is to what extent the embryological studies of the last 50 years have confirmed or rendered probable this "theory of recapitulation." In the first place it must be noted that the recapitulation theory is itself a deduction from the theory of evolution. The facts of embryology, particularly of vertebrate embryology, and of larval history receive, it is argued, an explanation on the view that the successive stages of development are, on the whole, records of adult stages of structure which the species has passed through in its evolution. Whether this statement will bear a critical verbal examination I will not now pause to inquire, for it is more important to determine whether any independent facts can be alleged in favour of the theory. If it could be shown, as was stated to be the case by L. Agassiz, that ancient and extinct forms of life present features of structure now only found in embryos, we should have a body of facts of the greatest importance in the present discussion. But as Huxley (See Huxley's "Scientific Memoirs", London, 1898, Vol. I. page 303: "There is no real parallel between the successive forms assumed in the development of the life of the individual at present, and those which have appeared at different epochs in the past." See also his Address to the Geological Society of London (1862) 'On the Palaeontological Evidence of Evolution', ibid. Vol. II. page 512.) has shown and as the whole course of palaeontological and embryological investigation has demonstrated, no such statement can be made. The extinct forms of life are very similar to those now existing and there is nothing specially embryonic about them. So that the facts, as we know them, lend no support to theory. But there is another class of facts which have been alleged in favour of the theory, viz. the facts which have been included in the generalisation known as the Law of v. Baer. The law asserts that embryos of different species of animals of the same group are more alike than the adults and that, the younger the embryo, the greater are the resemblances. If this law could be established it would undoubtedly be a strong argument in favour of the "recapitulation" explanation of the facts of embryology. But its truth has been seriously disputed. If it were true we should expect to find that the embryos of closely similar species would be indistinguishable from one another, but this is notoriously not the case. It is more difficult to meet the assertion when it is made in the form given above, for here we are dealing with matters of opinion. For instance, no one would deny that the embryo of a dogfish is different from the embryo of a rabbit, but there is room for difference of opinion when it is asserted that the difference is less than the difference between an adult dogfish and an adult rabbit. It would be perfectly true to say that the differences between the embryos concern other organs more than do the differences between the adults, but who is prepared to affirm that the presence of a cephalic coelom and of cranial segments, of external gills, of six gill slits, of the kidney tubes opening into the muscle-plate coelom, of an enormous yolk-sac, of a neurenteric canal, and the absence of any trace of an amnion, of an allantois and of a primitive streak are not morphological facts of as high an import as those implied by the differences between the adults? The generalisation undoubtedly had its origin in the fact that there is what may be called a family resemblance between embryos and larvae, but this resemblance, which is by no means exact, is largely superficial and does not extend to anatomical detail. It is useless to say, as Weismann has stated ("The Evolution Theory", by A. Weismann, English Translation, Vol. II. page 176, London, 1904.), that "it cannot be disputed that the rudiments [vestiges his translator means] of gill-arches and gill-clefts, which are peculiar to one stage of human ontogeny, give us every ground for concluding that we possessed fish-like ancestors." The question at issue is: did the pharyngeal arches and clefts of mammalian embryos ever discharge a branchial function in an adult ancestor of the mammalia? We cannot therefore, without begging the question at issue in the grossest manner, apply to them the terms "gill-arches" and "gill-clefts". That they are homologous with the "gill-arches" and "gill-clefts" of fishes is true; but there is no evidence to show that they ever discharged a branchial function. Until such evidence is forthcoming, it is beside the point to say that it "cannot be disputed" that they are evidence of a piscine ancestry. It must, therefore, be admitted that one outcome of the progress of embryological and palaeontological research for the last 50 years is negative. The recapitulation theory originated as a deduction from the evolution theory and as a deduction it still remains. Let us before leaving the subject apply another test. If the evolution theory and the recapitulation theory are both true, how is it that living birds are not only without teeth but have no rudiments of teeth at any stage of their existence? How is it that the missing digits in birds and mammals, the missing or reduced limb of snakes and whales, the reduced mandibulo-hyoid cleft of elasmobranch fishes are not present or relatively more highly developed in the embryo than in the adult? How is it that when a marked variation, such as an extra digit, or a reduced limb, or an extra segment, makes its appearance, it is not confined to the adult but can be seen all through the development? All the clear evidence we can get tends to show that marked variations, whether of reduction or increase, of organs are manifest during the whole of the development of the organ and do not merely affect the adult. And on reflection we see that it could hardly be otherwise. All such evidence is distinctly at variance with the theory of recapitulation, at least as applied to embryos. In the case of larvae of course the case will be different, for in them the organs are functional, and reduction in the adult will not be accompanied by reduction in the larva unless a change in the conditions of life of the larva enables it to occur. If after 50 years of research and close examination of the facts of embryology the recapitulation theory is still without satisfactory proof, it seems desirable to take a wider sweep and to inquire whether the facts of embryology cannot be included in a larger category. As has been pointed out by Huxley, development and life are co-extensive, and it is impossible to point to any period in the life of an organism when the developmental changes cease. It is true that these changes take place more rapidly at the commencement of life, but they are never wholly absent, and those which occur in the later or so-called adult stages of life do not differ in their essence, however much they may differ in their degree, from those which occur during the embryonic and larval periods. This consideration at once brings the changes of the embryonic period into the same category as those of the adult and suggests that an explanation which will account for the one will account for the other. What then is the problem we are dealing with? Surely it is this: Why does an organism as soon as it is established at the fertilisation of the ovum enter upon a cycle of transformations which never cease until death puts an end to them? In other words what is the meaning of that cycle of changes which all organisms present in a greater or less degree and which constitute the very essence of life? It is impossible to give an answer to this question so long as we remain within the precincts of Biology--and it is not my present purpose to penetrate beyond those precincts into the realms of philosophy. We have to do with an ultimate biological fact, with a fundamental property of living matter, which governs and includes all its other properties. How may this property be stated? Thus: it is a property of living matter to react in a remarkable way to external forces without undergoing destruction. The life-cycle, of which the embryonic and larval periods are a part, consists of the orderly interaction between the organism and its environment. The action of the environment produces certain morphological changes in the organism. These changes enable the organism to come into relation with new external forces, to move into what is practically a new environment, which in its turn produces further structural changes in the organism. These in their turn enable, indeed necessitate, the organism to move again into a new environment, and so the process continues until the structural changes are of such a nature that the organism is unable to adapt itself to the environment in which it finds itself. The essential condition of success in this process is that the organism should always shift into the environment to which its new structure is suited--any failure in this leading to the impairment of the organism. In most cases the shifting of the environment is a very gradual process (whether consisting in the very slight and gradual alteration in the relation of the embryo as a whole to the egg-shell or uterine wall, or in the relations of its parts to each other, or in the successive phases of adult life), and the morphological changes in connection with each step of it are but slight. But in some cases jumps are made such as we find in the phenomena known as hatching, birth, and metamorphosis. This property of reacting to the environment without undergoing destruction is, as has been stated, a fundamental property of organisms. It is impossible to conceive of any matter, to which the term living could be applied, being without it. And with this property of reacting to the environment goes the further property of undergoing a change which alters the relation of the organism to the old environment and places it in a new environment. If this reasoning is correct, it necessarily follows that this property must have been possessed by living matter at its first appearance on the earth. In other words living matter must always have presented a life-cycle, and the question arises what kind of modification has that cycle undergone? Has it increased or diminished in duration and complexity since organisms first appeared on the earth? The current view is that the cycle was at first very short and that it has increased in length by the evolutionary creation of new adult phases, that these new phases are in addition to those already existing and that each of them as it appears takes over from the preceding adult phase the functional condition of the reproductive organs. According to the same view the old adult phases are not obliterated but persist in a more or less modified form as larval stages. It is further supposed that as the life-history lengthens at one end by the addition of new adult phases, it is shortened at the other by the abbreviation of embryonic development and by the absorption of some of the early larval stages into the embryonic period; but on the whole the lengthening process has exceeded that of shortening, so that the whole life-history has, with the progress of evolution, become longer and more complicated. Now there can be no doubt that the life-history of organisms has been shortened in the way above suggested, for cases are known in which this can practically be seen to occur at the present day. But the process of lengthening by the creation of new stages at the other end of the life-cycle is more difficult to conceive and moreover there is no evidence for its having occurred. This, indeed, may have occurred, as is suggested below, but the evidence we have seems to indicate that evolutionary modification has proceeded by ALTERING and not by SUPERSEDING: that is to say that each stage in the life-history, as we see it to-day, has proceeded from a corresponding stage in a former era by the modification of that stage and not by the creation of a new one. Let me, at the risk of repetition, explain my meaning more fully by taking a concrete illustration. The mandibulo-hyoid cleft (spiracle) of the elasmobranch fishes, the lateral digits of the pig's foot, the hind-limbs of whales, the enlarged digit of the ostrich's foot are supposed to be organs which have been recently modified. This modification is not confined to the final adult stage of the life-history but characterises them throughout the whole of their development. A stage with a reduced spiracle does not proceed in development from a preceding stage in which the spiracle shows no reduction: it is reduced at its first appearance. The same statement may be made of organs which have entirely disappeared in the adult, such as bird's teeth and snake's fore-limbs: the adult stage in which they have disappeared is not preceded by embryonic stages in which the teeth and limbs or rudiments of them are present. In fact the evidence indicates that adult variations of any part are accompanied by precedent variations in the same direction in the embryo. The evidence seems to show, not that a stage is added on at the end of the life-history, but only that some of the stages in the life-history are modified. Indeed, on the wider view of development taken in this essay, a view which makes it coincident with life, one would not expect often to find, even if new stages are added in the course of evolution, that they are added at the end of the series when the organism has passed through its reproductive period. It is possible of course that new stages have been intercalated in the course of the life-history, though it is difficult to see how this has occurred. It is much more likely, if we may judge from available evidence, that every stage has had its counterpart in the ancestral form from which it has been derived by descent with modification. Just as the adult phase of the living form differs, owing to evolutionary modification, from the adult phase of the ancestor from which it has proceeded, so each larval phase will differ for the same reason from the corresponding larval phase in the life-history of the ancestor. Inasmuch as the organism is variable at every stage of its independent existence and is exposed to the action of natural selection there is no reason why it should escape modification at any stage. If there is any truth in these considerations it would seem to follow that at the dawn of life the life-cycle must have been, either in posse or in esse, at least as long as it is at the present time, and that the peculiarity of passing through a series of stages in which new characters are successively evolved is a primordial quality of living matter. Before leaving this part of the subject, it is necessary to touch upon another aspect of it. What are these variations in structure which succeed one another in the life-history of an organism? I am conscious that I am here on the threshold of a chamber which contains the clue to some of our difficulties, and that I cannot enter it. Looked at from one point of view they belong to the class of genetic variations, which depend upon the structure or constitution of the protoplasm; but instead of appearing in different zygotes (A zygote is a fertilised ovum, i.e. a new organism resulting from the fusion of an ovum and a spermatozoon.), they are present in the same zygote though at different times in its life-history. They are of the same order as the mutational variations of the modern biologist upon which the appearance of a new character depends. What is a genetic or mutational variation? It is a genetic character which was not present in either of the parents. But these "growth variations" were present in the parents, and in this they differ from mutational variations. But what are genetic characters? They are characters which must appear if any development occurs. They are usually contrasted with "acquired characters," using the expression "acquired character" in the Lamarckian sense. But strictly speaking they ARE acquired characters, for the zygote at first has none of the characters which it subsequently acquires, but only the power of acquiring them in response to the action of the environment. But the characters so acquired are not what we technically understand and what Lamarck meant by "acquired characters." They are genetic characters, as defined above. What then are Lamarck's "acquired characters"? They are variations in genetic characters caused in a particular way. There are, in fact, two kinds of variation in genetic characters depending on the mode of causation. Firstly, there are those variations consequent upon a variation in the constitution of the protoplasm of a particular zygote, and independent of the environment in which the organism develops, save in so far as this simply calls them forth: these are the so-called genetic or mutational variations. Secondly, there are those variations which occur in zygotes of similar germinal constitution and which are caused solely by differences in the environment to which the individuals are respectively exposed: these are the "acquired characters" of Lamarck and of authors generally. In consequence of this double sense in which the term "acquired characters" may be used, great confusion may and does occur. If the protoplasm be compared to a machine, and the external conditions to the hand that works the machine, then it may be said that, as the machine can only work in one way, it can only produce one kind of result (genetic character), but the particular form or quality (Lamarckian "acquired character") of the result will depend upon the hand that works the machine (environment), just as the quality of the sound produced by a fiddle depends entirely upon the hand which plays upon it. It would be improper to apply the term "mutation" to those genetic characters which are not new characters or new variants of old characters, but such genetic characters are of the same nature as those characters to which the term mutation has been applied. It may be noticed in passing that it is very questionable if the modern biologist has acted in the real interests of science in applying the term mutation in the sense in which he has applied it. The genetic characters of organisms come from one of two sources: either they are old characters and are due to the action of what we call inheritance or they are new and are due to what we call variation. If the term mutation is applied to the actual alteration of the machinery of the protoplasm, no objection can be felt to its use; but if it be applied, as it is, to the product of the action of the altered machine, viz. to the new genetic character, it leads to confusion. Inheritance is the persistence of the structure of the machine; characters are the products of the working of the machine; variation in genetic characters is due to the alteration (mutation) in the arrangement of the machinery, while variation in acquired characters (Lamarckian) is due to differences in the mode of working the machinery. The machinery when it starts (in the new zygote) has the power of grinding out certain results, which we call the characters of the organism. These appear at successive intervals of time, and the orderly manifestation of them is what we call the life-history of the organism. This brings us back to the question with which we started this discussion, viz. what is the relation of these variations in structure, which successively appear in an organism and constitute its life-history, to the mutational variations which appear in different organisms of the same brood or species. The question is brought home to us when we ask what is a bud-sport, such as a nectarine appearing on a peach-tree? From one point of view, it is simply a mutation appearing in asexual reproduction; from another it is one of these successional characters ("growth variations") which constitute the life-history of the zygote, for it appears in the same zygote which first produces a peach. Here our analogy of a machine which only works in one way seems to fail us, for these bud-sports do not appear in all parts of the organism, only in certain buds or parts of it, so that one part of the zygotic machine would appear to work differently to another. To discuss this question further would take us too far from our subject. Suffice it to say that we cannot answer it, any more than we can this further question of burning interest at the present day, viz. to what extent and in what manner is the machine itself altered by the particular way in which it is worked. In connection with this question we can only submit one consideration: the zygotic machine can, by its nature, only work once, so that any alteration in it can only be ascertained by studying the replicas of it which are produced in the reproductive organs. It is a peculiarity that the result which we call the ripening of the generative organs nearly always appears among the final products of the action of the zygotic machine. It is remarkable that this should be the case. What is the reason of it? The late appearance of functional reproductive organs is almost a universal law, and the explanation of it is suggested by expressing the law in another way, viz. that the machine is almost always so constituted that it ceases to work efficiently soon after the reproductive organs have sufficiently discharged their function. Why this should occur we cannot explain: it is an ultimate fact of nature, and cannot be included in any wider category. The period during which the reproductive organs can act may be short as in ephemerids or long as in man and trees, and there is no reason to suppose that their action damages the vital machinery, though sometimes, as in the case of annual plants (Metschnikoff), it may incidentally do so; but, long or short, the cessation of their actions is always a prelude to the end. When they and their action are impaired, the organism ceases to react with precision to the environment, and the organism as a whole undergoes retrogressive changes. It has been pointed out above that there is reason to believe that at the dawn of life the life-cycle was, EITHER IN ESSE OR IN POSSE, at least as long as it is at the present time. The qualification implied by the words in italics is necessary, for it is clearly possible that the external conditions then existing were not suitable for the production of all the stages of the potential life-history, and that what we call organic evolution has consisted in a gradual evolution of new environments to which the organism's innate capacity of change has enabled it to adapt itself. We have warrant for this possibility in the case of the Axolotl and in other similar cases of neoteny. And these cases further bring home to us the fact, to which I have already referred, that the full development of the functional reproductive organs is nearly always associated with the final stages of the life-history. On this view of the succession of characters in the life-history of organisms, how shall we explain the undoubted fact that the development of buds hardly ever presents any phenomena corresponding to the embryonic and larval changes? The reason is clearly this, that budding usually occurs after the embryonic stage is past; when the characters of embryonic life have been worked out by the machine. When it takes place at an early stage in embryonic life, as it does in cases of so-called embryonic fission, the product shows, either partly or entirely, phenomena similar to those of embryonic development. The only case known to me in which budding by the adult is accompanied by morphological features similar to those displayed by embryos is furnished by the budding of the medusiform spore-sacs of hydrozoon polyps. But this case is exceptional, for here we have to do with an attempt, which fails, to form a free-swimming organism, the medusa; and the vestiges which appear in the buds are the umbrella-cavity, marginal tentacles, circular canal, etc., of the medusa arrested in development. But the question still remains, are there no cases in which, as implied by the recapitulation theory, variations in any organ are confined to the period in which the organ is functional and do not affect it in the embryonic stages? The teeth of the whalebone whales may be cited as a case in which this is said to occur; but here the teeth are only imperfectly developed in the embryo and are soon absorbed. They have been affected by the change which has produced their disappearance in the adult, but not to complete extinction. Nor are they now likely to be extinguished, for having become exclusively embryonic they are largely protected from the action of natural selection. This consideration brings up a most important aspect of the question, so far as disappearing organs are concerned. Every organ is laid down at a certain period in the embryo and undergoes a certain course of growth until it obtains full functional development. When for any cause reduction begins, it is affected at all stages of its growth, unless it has functional importance in the larva, and in some cases its life is shortened at one or both ends. In cases, as in that of the whale's teeth, in which it entirely disappears in the adult, the latter part of its life is cut off; in others, the beginning of its life may be deferred. This happens, for instance, with the spiracle of many Elasmobranchs, which makes its appearance after the hyobranchial cleft, not before it as it should do, being anterior to it in position, and as it does in the Amniota in which it shows no reduction in size as compared with the other pharyngeal clefts. In those Elasmobranchs in which it is absent in the adult but present in the embryo (e.g. Carcharias) its life is shortened at both ends. Many more instances of organs, of which the beginning and end have been cut off, might be mentioned; e.g. the muscle-plate coelom of Aves, the primitive streak and the neurenteric canal of amniote blastoderms. In yet other cases in which the reduced organ is almost on the verge of disappearance, it may appear for a moment and disappear more than once in the course of development. As an instance of this striking phenomenon I may mention the neurenteric canal of avine embryos, and the anterior neuropore of Ascidians. Lastly the reduced organ may disappear in the developing stages before it does so in the adult. As an instance of this may be mentioned the mandibular palp of those Crustacea with zoaea larvae. This structure disappears in the larva only to reappear in a reduced form in later stages. In all these cases we are dealing with an organ which, we imagine, attained a fuller functional development at some previous stage in race-history, but in most of them we have no proof that it did so. It may be, and the possibility must not be lost sight of, that these organs never were anything else than functionless and that though they have been got rid of in the adult by elimination in the course of time, they have been able to persist in embryonic stages which are protected from the full action of natural selection. There is no reason to suppose that living matter at its first appearance differed from non-living matter in possessing only properties conducive to its well-being and prolonged existence. No one thinks that the properties of the various forms of inorganic matter are all strictly related to external conditions. Of what use to the diamond is its high specific gravity and high refrangibility, and to gold of its yellow colour and great weight? These substances continue to exist in virtue of other properties than these. It is impossible to suppose that the properties of living matter at its first appearance were all useful to it, for even now after aeons of elimination we find that it possesses many useless organs and that many of its relations to the external world are capable of considerable improvement. In writing this essay I have purposely refrained from taking a definite position with regard to the problems touched. My desire has been to write a chapter showing the influence of Darwin's work so far as Embryology is concerned, and the various points which come up for consideration in discussing his views. Darwin was the last man who would have claimed finality for any of his doctrines, but he might fairly have claimed to have set going a process of intellectual fermentation which is still very far from completion. XI. THE PALAEONTOLOGICAL RECORD. By W.B. Scott. Professor of Geology in the University of Princeton, U.S.A. I. ANIMALS. To no branch of science did the publication of "The Origin of Species" prove to be a more vivifying and transforming influence than to Palaeontology. This science had suffered, and to some extent, still suffers from its rather anomalous position between geology and biology, each of which makes claim to its territory, and it was held in strict bondage to the Linnean and Cuvierian dogma that species were immutable entities. There is, however, reason to maintain that this strict bondage to a dogma now abandoned, was not without its good side, and served the purpose of keeping the infant science in leading-strings until it was able to walk alone, and preventing a flood of premature generalisations and speculations. As Zittel has said: "Two directions were from the first apparent in palaeontological research--a stratigraphical and a biological. Stratigraphers wished from palaeontology mainly confirmation regarding the true order or relative age of zones of rock-deposits in the field. Biologists had, theoretically at least, the more genuine interest in fossil organisms as individual forms of life." (Zittel, "History of Geology and Palaeontology", page 363, London, 1901.) The geological or stratigraphical direction of the science was given by the work of William Smith, "the father of historical geology," in the closing decade of the eighteenth century. Smith was the first to make a systematic use of fossils in determining the order of succession of the rocks which make up the accessible crust of the earth, and this use has continued, without essential change, to the present day. It is true that the theory of evolution has greatly modified our conceptions concerning the introduction of new species and the manner in which palaeontological data are to be interpreted in terms of stratigraphy, but, broadly speaking, the method remains fundamentally the same as that introduced by Smith. The biological direction of palaeontology was due to Cuvier and his associates, who first showed that fossils were not merely varieties of existing organisms, but belonged to extinct species and genera, an altogether revolutionary conception, which startled the scientific world. Cuvier made careful studies, especially of fossil vertebrates, from the standpoint of zoology and was thus the founder of palaeontology as a biological science. His great work on "Ossements Fossiles" (Paris, 1821) has never been surpassed as a masterpiece of the comparative method of anatomical investigation, and has furnished to the palaeontologist the indispensable implements of research. On the other hand, Cuvier's theoretical views regarding the history of the earth and its successive faunas and floras are such as no one believes to-day. He held that the earth had been repeatedly devastated by great cataclysms, which destroyed every living thing, necessitating an entirely new creation, thus regarding the geological periods as sharply demarcated and strictly contemporaneous for the whole earth, and each species of animal and plant as confined to a single period. Cuvier's immense authority and his commanding personality dominated scientific thought for more than a generation and marked out the line which the development of palaeontology was to follow. The work was enthusiastically taken up by many very able men in the various European countries and in the United States, but, controlled as it was by the belief in the fixity of species, it remained almost entirely descriptive and consisted in the description and classification of the different groups of fossil organisms. As already intimated, this narrowness of view had its compensations, for it deferred generalisations until some adequate foundations for these had been laid. Dominant as it was, Cuvier's authority was slowly undermined by the progress of knowledge and the way was prepared for the introduction of more rational conceptions. The theory of "Catastrophism" was attacked by several geologists, most effectively by Sir Charles Lyell, who greatly amplified the principles enunciated by Hutton and Playfair in the preceding century, and inaugurated a new era in geology. Lyell's uniformitarian views of the earth's history and of the agencies which had wrought its changes, had undoubted effect in educating men's minds for the acceptance of essentially similar views regarding the organic world. In palaeontology too the doctrine of the immutability of species, though vehemently maintained and reasserted, was gradually weakening. In reviewing long series of fossils, relations were observed which pointed to genetic connections and yet were interpreted as purely ideal. Agassiz, for example, who never accepted the evolutionary theory, drew attention to facts which could be satisfactorily interpreted only in terms of that theory. Among the fossils he indicated "progressive," "synthetic," "prophetic," and "embryonic" types, and pointed out the parallelism which obtains between the geological succession of ancient animals and the ontogenetic development of recent forms. In Darwin's words: "This view accords admirably well with our theory." ("Origin of Species" (6th edition), page 310.) Of similar import were Owen's views on "generalised types" and "archetypes." The appearance of "The Origin of Species" in 1859 revolutionised all the biological sciences. From the very nature of the case, Darwin was compelled to give careful consideration to the palaeontological evidence; indeed, it was the palaeontology and modern distribution of animals in South America which first led him to reflect upon the great problem. In his own words: "I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos; secondly, by the manner in which closely allied animals replace one another in proceeding southward over the Continent; and thirdly, by the South American character of most of the productions of the Galapagos archipelago, and more especially by the manner in which they differ slightly on each island of the group." ("Life and Letters of Charles Darwin", I. page 82.) In the famous tenth and eleventh chapters of the "Origin", the palaeontological evidence is examined at length and the imperfection of the geological record is strongly emphasised. The conclusion is reached, that, in view of this extreme imperfection, palaeontology could not reasonably be expected to yield complete and convincing proof of the evolutionary theory. "I look at the geological record as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines." ("Origin of Species", page 289.) Yet, aside from these inevitable difficulties, he concludes, that "the other great leading facts in palaeontology agree admirably with the theory of descent with modification through variation and natural selection." (Ibid. page 313.) Darwin's theory gave an entirely new significance and importance to palaeontology. Cuvier's conception of the science had been a limited, though a lofty one. "How glorious it would be if we could arrange the organised products of the universe in their chronological order!... The chronological succession of organised forms, the exact determination of those types which appeared first, the simultaneous origin of certain species and their gradual decay, would perhaps teach us as much about the mysteries of organisation as we can possibly learn through experiments with living organisms." (Zittel op. cit. page 140.) This, however, was rather the expression of a hope for the distant future than an account of what was attainable, and in practice the science remained almost purely descriptive, until Darwin gave it a new standpoint, new problems and an altogether fresh interest and charm. The revolution thus accomplished is comparable only to that produced by the Copernican astronomy. From the first it was obvious that one of the most searching tests of the evolutionary theory would be given by the advance of palaeontological discovery. However imperfect the geological record might be, its ascertained facts would necessarily be consistent, under any reasonable interpretation, with the demands of a true theory; otherwise the theory would eventually be overwhelmed by the mass of irreconcilable data. A very great stimulus was thus given to geological investigation and to the exploration of new lands. In the last forty years, the examination of North and South America, of Africa and Asia has brought to light many chapters in the history of life, which are astonishingly full and complete. The flood of new material continues to accumulate at such a rate that it is impossible to keep abreast of it, and the very wealth of the collections is a source of difficulty and embarrassment. In modern palaeontology phylogenetic questions and problems occupy a foremost place and, as a result of the labours of many eminent investigators in many lands, it may be said that this science has proved to be one of the most solid supports of Darwin's theory. True, there are very many unsolved problems, and the discouraged worker is often tempted to believe that the fossils raise more questions than they answer. Yet, on the other hand, the whole trend of the evidence is so strongly in favour of the evolutionary doctrine, that no other interpretation seems at all rational. To present any adequate account of the palaeontological record from the evolutionary standpoint, would require a large volume and a singularly unequal, broken and disjointed history it would be. Here the record is scanty, interrupted, even unintelligible, while there it is crowded with embarrassing wealth of material, but too often these full chapters are separated by such stretches of unrecorded time, that it is difficult to connect them. It will be more profitable to present a few illustrative examples than to attempt an outline of the whole history. At the outset, the reader should be cautioned not to expect too much, for the task of determining phylogenies fairly bristles with difficulties and encounters many unanswered questions. Even when the evidence seems to be as copious and as complete as could be wished, different observers will put different interpretations upon it, as in the notorious case of the Steinheim shells. (In the Miocene beds of Steinheim, Wurtemberg, occur countless fresh-water shells, which show numerous lines of modification, but these have been very differently interpreted by different writers.) The ludicrous discrepances which often appear between the phylogenetic "trees" of various writers have cast an undue discredit upon the science and have led many zoologists to ignore palaeontology altogether as unworthy of serious attention. One principal cause of these discrepant and often contradictory results is our ignorance concerning the exact modes of developmental change. What one writer postulates as almost axiomatic, another will reject as impossible and absurd. Few will be found to agree as to how far a given resemblance is offset by a given unlikeness, and so long as the question is one of weighing evidence and balancing probabilities, complete harmony is not to be looked for. These formidable difficulties confront us even in attempting to work out from abundant material a brief chapter in the phylogenetic history of some small and clearly limited group, and they become disproportionately greater, when we extend our view over vast periods of time and undertake to determine the mutual relationships of classes and types. If the evidence were complete and available, we should hardly be able to unravel its infinite complexity, or to find a clue through the mazes of the labyrinth. "Our ideas of the course of descent must of necessity be diagrammatic." (D.H. Scott, "Studies in Fossil Botany", page 524. London, 1900.) Some of the most complete and convincing examples of descent with modification are to be found among the mammals, and nowhere more abundantly than in North America, where the series of continental formations, running through the whole Tertiary period, is remarkably full. Most of these formations contain a marvellous wealth of mammalian remains and in an unusual state of preservation. The oldest Eocene (Paleocene) has yielded a mammalian fauna which is still of prevailingly Mesozoic character, and contains but few forms which can be regarded as ancestral to those of later times. The succeeding fauna of the lower Eocene proper (Wasatch stage) is radically different and, while a few forms continue over from the Paleocene, the majority are evidently recent immigrants from some region not yet identified. From the Wasatch onward, the development of many phyla may be traced in almost unbroken continuity, though from time to time the record is somewhat obscured by migrations from the Old World and South America. As a rule, however, it is easy to distinguish between the immigrant and the indigenous elements of the fauna. From their gregarious habits and individual abundance, the history of many hoofed animals is preserved with especial clearness. So well known as to have become a commonplace, is the phylogeny of the horses, which, contrary to all that would have been expected, ran the greater part of its course in North America. So far as it has yet been traced, the line begins in the lower Eocene with the genus Eohippus, a little creature not much larger than a cat, which has a short neck, relatively short limbs, and in particular, short feet, with four functional digits and a splint-like rudiment in the fore-foot, three functional digits and a rudiment in the hind-foot. The forearm bones (ulna and radius) are complete and separate, as are also the bones of the lower leg (fibula and tibia). The skull has a short face, with the orbit, or eye-socket, incompletely enclosed with bone, and the brain-case is slender and of small capacity. The teeth are short-crowned, the incisors without "mark," or enamel pit, on the cutting edge; the premolars are all smaller and simpler than the molars. The pattern of the upper molars is so entirely different from that seen in the modern horses that, without the intermediate connecting steps, no one would have ventured to derive the later from the earlier plan. This pattern is quadritubercular, with four principal, conical cusps arranged in two transverse pairs, forming a square, and two minute cuspules between each transverse pair, a tooth which is much more pig-like than horse-like. In the lower molars the cusps have already united to form two crescents, one behind the other, forming a pattern which is extremely common in the early representatives of many different families, both of the Perissodactyla and the Artiodactyla. In spite of the manifold differences in all parts of the skeleton between Eohippus and the recent horses, the former has stamped upon it an equine character which is unmistakable, though it can hardly be expressed in words. Each one of the different Eocene and Oligocene horizons has its characteristic genus of horses, showing a slow, steady progress in a definite direction, all parts of the structure participating in the advance. It is not necessary to follow each of these successive steps of change, but it should be emphasised that the changes are gradual and uninterrupted. The genus Mesohippus, of the middle Oligocene, may be selected as a kind of half-way stage in the long progression. Comparing Mesohippus with Eohippus, we observe that the former is much larger, some species attaining the size of a sheep, and has a relatively longer neck, longer limbs and much more elongate feet, which are tridactyl, and the middle toe is so enlarged that it bears most of the weight, while the lateral digits are very much more slender. The fore-arm bones have begun to co-ossify and the ulna is greatly reduced, while the fibula, though still complete, is hardly more than a thread of bone. The skull has a longer face and a nearly enclosed orbit, and the brain-case is fuller and more capacious, the internal cast of which shows that the brain was richly convoluted. The teeth are still very short-crowned, but the upper incisors plainly show the beginning of the "mark"; the premolars have assumed the molar form, and the upper molars, though plainly derived from those of Eohippus, have made a long stride toward the horse pattern, in that the separate cusps have united to form a continuous outer wall and two transverse crests. In the lower Miocene the interesting genus Desmatippus shows a further advance in the development of the teeth, which are beginning to assume the long-crowned shape, delaying the formation of roots; a thin layer of cement covers the crowns, and the transverse crests of the upper grinding teeth display an incipient degree of their modern complexity. This tooth-pattern is strictly intermediate between the recent type and the ancient type seen in Mesohippus and its predecessors. The upper Miocene genera, Protohippus and Hipparion are, to all intents and purposes, modern in character, but their smaller size, tridactyl feet and somewhat shorter-crowned teeth are reminiscences of their ancestry. From time to time, when a land-connection between North America and Eurasia was established, some of the successive equine genera migrated to the Old World, but they do not seem to have gained a permanent footing there until the end of the Miocene or beginning of the Pliocene, eventually diversifying into the horses, asses, and zebras of Africa, Asia and Europe. At about the same period, the family extended its range to South America and there gave rise to a number of species and genera, some of them extremely peculiar. For some unknown reason, all the horse tribe had become extinct in the western hemisphere before the European discovery, but not until after the native race of man had peopled the continents. In addition to the main stem of equine descent, briefly considered in the foregoing paragraphs, several side-branches were given off at successive levels of the stem. Most of these branches were short-lived, but some of them flourished for a considerable period and ramified into many species. Apparently related to the horses and derived from the same root-stock is the family of the Palaeotheres, confined to the Eocene and Oligocene of Europe, dying out without descendants. In the earlier attempts to work out the history of the horses, as in the famous essay of Kowalevsky ("Sur l'Anchitherium aurelianense Cuv. et sur l'histoire paleontologique des Chevaux", "Mem. de l'Acad. Imp. des Sc. de St Petersbourg", XX. no. 5, 1873.), the Palaeotheres were placed in the direct line, because the number of adequately known Eocene mammals was then so small, that Cuvier's types were forced into various incongruous positions, to serve as ancestors for unrelated series. The American family of the Titanotheres may also be distantly related to the horses, but passed through an entirely different course of development. From the lower Eocene to the lower sub-stage of the middle Oligocene the series is complete, beginning with small and rather lightly built animals. Gradually the stature and massiveness increase, a transverse pair of nasal horns make their appearance and, as these increase in size, the canine tusks and incisors diminish correspondingly. Already in the oldest known genus the number of digits had been reduced to four in the fore-foot and three in the hind, but there the reduction stops, for the increasing body-weight made necessary the development of broad and heavy feet. The final members of the series comprise only large, almost elephantine animals, with immensely developed and very various nasal horns, huge and massive heads, and altogether a grotesque appearance. The growth of the brain did not at all keep pace with the increase of the head and body, and the ludicrously small brain may will have been one of the factors which determined the startlingly sudden disappearance and extinction of the group. Less completely known, but of unusual interest, is the genealogy of the rhinoceros family, which probably, though not certainly, was likewise of American origin. The group in North America at least, comprised three divisions, or sub-families, of very different proportions, appearance and habits, representing three divergent lines from the same stem. Though the relationship between the three lines seems hardly open to question, yet the form ancestral to all of them has not yet been identified. This is because of our still very incomplete knowledge of several perissodactyl genera of the Eocene, any one of which may eventually prove to be the ancestor sought for. The first sub-family is the entirely extinct group of Hyracodonts, which may be traced in successive modifications through the upper Eocene, lower and middle Oligocene, then disappearing altogether. As yet, the hyracodonts have been found only in North America, and the last genus of the series, Hyracodon, was a cursorial animal. Very briefly stated, the modifications consist in a gradual increase in size, with greater slenderness of proportions, accompanied by elongation of the neck, limbs, and feet, which become tridactyl and very narrow. The grinding teeth have assumed the rhinoceros-like pattern and the premolars resemble the molars in form; on the other hand, the front teeth, incisors and canines, have become very small and are useless as weapons. As the animal had no horns, it was quite defenceless and must have found its safety in its swift running, for Hyracodon displays many superficial resemblances to the contemporary Oligocene horses, and was evidently adapted for speed. It may well have been the competition of the horses which led to the extinction of these cursorial rhinoceroses. The second sub-family, that of the Amynodonts, followed a totally different course of development, becoming short-legged and short-footed, massive animals, the proportions of which suggest aquatic habits; they retained four digits in the front foot. The animal was well provided with weapons in the large canine tusks, but was without horns. Some members of this group extended their range to the Old World, but they all died out in the middle Oligocene, leaving no successors. The sub-family of the true rhinoceroses cannot yet be certainly traced farther back than to the base of the middle Oligocene, though some fragmentary remains found in the lower Oligocene are probably also referable to it. The most ancient and most primitive member of this series yet discovered, the genus Trigonias, is unmistakably a rhinoceros, yet much less massive, having more the proportions of a tapir; it had four toes in the front foot, three in the hind, and had a full complement of teeth, except for the lower canines, though the upper canines are about to disappear, and the peculiar modification of the incisors, characteristic of the true rhinoceroses, is already apparent; the skull is hornless. Representatives of this sub-family continue through the Oligocene and Miocene of North America, becoming rare and localised in the Pliocene and then disappearing altogether. In the Old World, on the other hand, where the line appeared almost as early as it did in America, this group underwent a great expansion and ramification, giving rise not only to the Asiatic and African forms, but also to several extinct series. Turning now to the Artiodactyla, we find still another group of mammals, that of the camels and llamas, which has long vanished from North America, yet took its rise and ran the greater part of its course in that continent. From the lower Eocene onward the history of this series is substantially complete, though much remains to be learned concerning the earlier members of the family. The story is very like that of the horses, to which in many respects it runs curiously parallel. Beginning with very small, five-toed animals, we observe in the successive genera a gradual transformation in all parts of the skeleton, an elongation of the neck, limbs and feet, a reduction of the digits from five to two, and eventually the coalescence of the remaining two digits into a "cannon-bone." The grinding teeth, by equally gradual steps, take on the ruminant pattern. In the upper Miocene the line divides into the two branches of the camels and llamas, the former migrating to Eurasia and the latter to South America, though representatives of both lines persisted in North America until a very late period. Interesting side-branches of this line have also been found, one of which ended in the upper Miocene in animals which had almost the proportions of the giraffes and must have resembled them in appearance. The American Tertiary has yielded several other groups of ruminant-like animals, some of which form beautifully complete evolutionary series, but space forbids more than this passing mention of them. It was in Europe that the Artiodactyla had their principal development, and the upper Eocene, Oligocene and Miocene are crowded with such an overwhelming number and variety of forms that it is hardly possible to marshal them in orderly array and determine their mutual relationships. Yet in this chaotic exuberance of life, certain important facts stand out clearly, among these none is of greater interest and importance than the genealogy of the true Ruminants, or Pecora, which may be traced from the upper Eocene onward. The steps of modification and change are very similar to those through which the camel phylum passed in North America, but it is instructive to note that, despite their many resemblances, the two series can be connected only in their far distant beginnings. The pecoran stock became vastly more expanded and diversified than did the camel line and was evidently more plastic and adaptable, spreading eventually over all the continents except Australia, and forming to-day one of the dominant types of mammals, while the camels are on the decline and not far from extinction. The Pecora successively ramified into the deer, antelopes, sheep, goats and oxen, and did not reach North America till the Miocene, when they were already far advanced in specialisation. To this invasion of the Pecora, or true ruminants, it seems probable that the decline and eventual disappearance of the camels is to be ascribed. Recent discoveries in Egypt have thrown much light upon a problem which long baffled the palaeontologist, namely, the origin of the elephants. (C.W. Andrews, "On the Evolution of the Proboscidea", "Phil. Trans. Roy. Soc." London, Vol. 196, 1904, page 99.) Early representatives of this order, Mastodons, had appeared almost simultaneously (in the geological sense of that word) in the upper Miocene of Europe and North America, but in neither continent was any more ancient type known which could plausibly be regarded as ancestral to them. Evidently, these problematical animals had reached the northern continents by migrating from some other region, but no one could say where that region lay. The Eocene and Oligocene beds of the Fayoum show us that the region sought for is Africa, and that the elephants form just such a series of gradual modifications as we have found among other hoofed animals. The later steps of the transformation, by which the mastodons lost their lower tusks, and their relatively small and simple grinding teeth acquired the great size and highly complex structure of the true elephants, may be followed in the uppermost Miocene and Pliocene fossils of India and southern Europe. Egypt has also of late furnished some very welcome material which contributes to the solution of another unsolved problem which had quite eluded research, the origin of the whales. The toothed-whales may be traced back in several more or less parallel lines as far as the lower Miocene, but their predecessors in the Oligocene are still so incompletely known that safe conclusions can hardly be drawn from them. In the middle Eocene of Egypt, however, has been found a small, whale-like animal (Protocetus), which shows what the ancestral toothed-whale was like, and at the same time seems to connect these thoroughly marine mammals with land-animals. Though already entirely adapted to an aquatic mode of life, the teeth, skull and backbone of Protocetus display so many differences from those of the later whales and so many approximations to those of primitive, carnivorous land-mammals, as, in a large degree, to bridge over the gap between the two groups. Thus one of the most puzzling of palaeontological questions is in a fair way to receive a satisfactory answer. The origin of the whalebone-whales and their relations to the toothed-whales cannot yet be determined, since the necessary fossils have not been discovered. Among the carnivorous mammals, phylogenetic series are not so clear and distinct as among the hoofed animals, chiefly because the carnivores are individually much less abundant, and well-preserved skeletons are among the prizes of the collector. Nevertheless, much has already been learned concerning the mutual relations of the carnivorous families, and several phylogenetic series, notably that of the dogs, are quite complete. It has been made extremely probable that the primitive dogs of the Eocene represent the central stock, from which nearly or quite all the other families branched off, though the origin and descent of the cats have not yet been determined. It should be clearly understood that the foregoing account of mammalian descent is merely a selection of a few representative cases and might be almost indefinitely extended. Nothing has been said, for example, of the wonderful museum of ancient mammalian life which is entombed in the rocks of South America, especially of Patagonia, and which opens a world so entirely different from that of the northern continents, yet exemplifying the same laws of "descent with modification." Very beautiful phylogenetic series have already been established among these most interesting and marvellously preserved fossils, but lack of space forbids a consideration of them. The origin of the mammalia, as a class, offers a problem of which palaeontology can as yet present no definitive solution. Many morphologists regard the early amphibia as the ancestral group from which the mammals were derived, while most palaeontologists believe that the mammals are descended from the reptiles. The most ancient known mammals, those from the upper Triassic of Europe and North America, are so extremely rare and so very imperfectly known, that they give little help in determining the descent of the class, but, on the other hand, certain reptilian orders of the Permian period, especially well represented in South Africa, display so many and such close approximations to mammalian structure, as strongly to suggest a genetic relationship. It is difficult to believe that all those likenesses should have been independently acquired and are without phylogenetic significance. Birds are comparatively rare as fossils and we should therefore look in vain among them for any such long and closely knit series as the mammals display in abundance. Nevertheless, a few extremely fortunate discoveries have made it practically certain that birds are descended from reptiles, of which they represent a highly specialised branch. The most ancient representative of this class is the extraordinary genus Archaeopteryx from the upper Jurassic of Bavaria, which, though an unmistakable bird, retains so many reptilian structures and characteristics as to make its derivation plain. Not to linger over anatomical minutiae, it may suffice to mention the absence of a horny beak, which is replaced by numerous true teeth, and the long lizard-like tail, which is made up of numerous distinct vertebrae, each with a pair of quill-like feathers attached to it. Birds with teeth are also found in the Cretaceous, though in most other respects the birds of that period had attained a substantially modern structure. Concerning the interrelations of the various orders and families of birds, palaeontology has as yet little to tell us. The life of the Mesozoic era was characterised by an astonishing number and variety of reptiles, which were adapted to every mode of life, and dominated the air, the sea and the land, and many of which were of colossal proportions. Owing to the conditions of preservation which obtained during the Mesozoic period, the history of the reptiles is a broken and interrupted one, so that we can make out many short series, rather than any one of considerable length. While the relations of several reptilian orders can be satisfactorily determined, others still baffle us entirely, making their first known appearance in a fully differentiated state. We can trace the descent of the sea-dragons, the Ichthyosaurs and Plesiosaurs, from terrestrial ancestors, but the most ancient turtles yet discovered show us no closer approximation to any other order than do the recent turtles; and the oldest known Pterosaurs, the flying dragons of the Jurassic, are already fully differentiated. There is, however, no ground for discouragement in this, for the progress of discovery has been so rapid of late years, and our knowledge of Mesozoic life has increased with such leaps and bounds, that there is every reason to expect a solution of many of the outstanding problems in the near future. Passing over the lower vertebrates, for lack of space to give them any adequate consideration, we may briefly take up the record of invertebrate life. From the overwhelming mass of material it is difficult to make a representative selection and even more difficult to state the facts intelligibly without the use of unduly technical language and without the aid of illustrations. Several groups of the Mollusca, or shell-fish, yield very full and convincing evidence of their descent from earlier and simpler forms, and of these none is of greater interest than the Ammonites, an extinct order of the cephalopoda. The nearest living ally of the ammonites is the pearly nautilus, the other existing cephalopods, such as the squids, cuttle-fish, octopus, etc., are much more distantly related. Like the nautilus, the ammonites all possess a coiled and chambered shell, but their especial characteristic is the complexity of the "sutures." By sutures is meant the edges of the transverse partitions, or septa, where these join the shell-wall, and their complexity in the fully developed genera is extraordinary, forming patterns like the most elaborate oak-leaf embroidery, while in the nautiloids the sutures form simple curves. In the rocks of the Mesozoic era, wherever conditions of preservation are favourable, these beautiful shells are stored in countless multitudes, of an incredible variety of form, size and ornamentation, as is shown by the fact that nearly 5000 species have already been described. The ammonites are particularly well adapted for phylogenetic studies, because, by removing the successive whorls of the coiled shell, the individual development may be followed back in inverse order, to the microscopic "protoconch," or embryonic shell, which lies concealed in the middle of the coil. Thus the valuable aid of embryology is obtained in determining relationships. The descent of the ammonites, taken as a group, is simple and clear; they arose as a branch of the nautiloids in the lower Devonian, the shells known as goniatites having zigzag, angulated sutures. Late in the succeeding Carboniferous period appear shells with a truly ammonoid complexity of sutures, and in the Permian their number and variety cause them to form a striking element of the marine faunas. It is in the Mesozoic era, however, that these shells attain their full development; increasing enormously in the Triassic, they culminate in the Jurassic in the number of families, genera and species, in the complexity of the sutures, and in the variety of shell-ornamentation. A slow decline begins in the Cretaceous, ending in the complete extinction of the whole group at the end of that period. As a final phase in the history of the ammonites, there appear many so-called "abnormal" genera, in which the shell is irregularly coiled, or more or less uncoiled, in some forms becoming actually straight. It is interesting to observe that some of these genera are not natural groups, but are "polyphyletic," i.e. are each derived from several distinct ancestral genera, which have undergone a similar kind of degeneration. In the huge assembly of ammonites it is not yet possible to arrange all the forms in a truly natural classification, which shall express the various interrelations of the genera, yet several beautiful series have already been determined. In these series the individual development of the later general shows transitory stages which are permanent in antecedent genera. To give a mere catalogue of names without figures would not make these series more intelligible. The Brachiopoda, or "lamp-shells," are a phylum of which comparatively few survive to the present day; their shells have a superficial likeness to those of the bivalved Mollusca, but are not homologous with the latter, and the phylum is really very distinct from the molluscs. While greatly reduced now, these animals were incredibly abundant throughout the Palaeozoic era, great masses of limestone being often composed almost exclusively of their shells, and their variety is in keeping with their individual abundance. As in the case of the ammonites, the problem is to arrange this great multitude of forms in an orderly array that shall express the ramifications of the group according to a genetic system. For many brachiopods, both recent and fossil, the individual development, or ontogeny, has been worked out and has proved to be of great assistance in the problems of classification and phylogeny. Already very encouraging progress has been made in the solution of these problems. All brachiopods form first a tiny, embryonic shell, called the protegulum, which is believed to represent the ancestral form of the whole group, and in the more advanced genera the developmental stages clearly indicate the ancestral genera of the series, the succession of adult forms in time corresponding to the order of the ontogenetic stages. The transformation of the delicate calcareous supports of the arms, often exquisitely preserved, are extremely interesting. Many of the Palaeozoic genera had these supports coiled like a pair of spiral springs, and it has been shown that these genera were derived from types in which the supports were simply shelly loops. The long extinct class of crustacea known as the Trilobites are likewise very favourable subjects for phylogenetic studies. So far as the known record can inform us, the trilobites are exclusively Palaeozoic in distribution, but their course must have begun long before that era, as is shown by the number of distinct types among the genera of the lower Cambrian. The group reached the acme of abundance and relative importance in the Cambrian and Ordovician; then followed a long, slow decline, ending in complete and final disappearance before the end of the Permian. The newly-hatched and tiny trilobite larva, known as the protaspis, is very near to the primitive larval form of all the crustacea. By the aid of the correlated ontogenetic stages and the succession of the adult forms in the rocks, many phylogenetic series have been established and a basis for the natural arrangement of the whole class has been laid. Very instructive series may also be observed among the Echinoderms and, what is very rare, we are able in this sub-kingdom to demonstrate the derivation of one class from another. Indeed, there is much reason to believe that the extinct class Cystidea of the Cambrian is the ancestral group, from which all the other Echinoderms, star-fishes, brittle-stars, sea-urchins, feather-stars, etc., are descended. The foregoing sketch of the palaeontological record is, of necessity, extremely meagre, and does not represent even an outline of the evidence, but merely a few illustrative examples, selected almost at random from an immense body of material. However, it will perhaps suffice to show that the geological record is not so hopelessly incomplete as Darwin believed it to be. Since "The Origin of Species" was written, our knowledge of that record has been enormously extended and we now possess, no complete volumes, it is true, but some remarkably full and illuminating chapters. The main significance of the whole lies in the fact, that JUST IN PROPORTION TO THE COMPLETENESS OF THE RECORD IS THE UNEQUIVOCAL CHARACTER OF ITS TESTIMONY TO THE TRUTH OF THE EVOLUTIONARY THEORY. The test of a true, as distinguished from a false, theory is the manner in which newly discovered and unanticipated facts arrange themselves under it. No more striking illustration of this can be found than in the contrasted fates of Cuvier's theory and of that of Darwin. Even before Cuvier's death his views had been undermined and the progress of discovery soon laid them in irreparable ruin, while the activity of half-a-century in many different lines of inquiry has established the theory of evolution upon a foundation of ever growing solidity. It is Darwin's imperishable glory that he prescribed the lines along which all the biological sciences were to advance to conquests not dreamed of when he wrote. XII. THE PALAEONTOLOGICAL RECORD. By D.H. Scott, F.R.S. President of the Linnean Society. II. PLANTS. There are several points of view from which the subject of the present essay may be regarded. We may consider the fossil record of plants in its bearing: I. on the truth of the doctrine of Evolution; II. on Phylogeny, or the course of Evolution; III. on the theory of Natural Selection. The remarks which follow, illustrating certain aspects only of an extensive subject, may conveniently be grouped under these three headings. I. THE TRUTH OF EVOLUTION. When "The Origin of Species" was written, it was necessary to show that the Geological Record was favourable to, or at least consistent with, the Theory of Descent. The point is argued, closely and fully, in Chapter X. "On the Imperfection of the Geological Record," and Chapter XI. "On the Geological Succession of Organic Beings"; there is, however, little about plants in these chapters. At the present time the truth of Evolution is no longer seriously disputed, though there are writers, like Reinke, who insist, and rightly so, that the doctrine is still only a belief, rather than an established fact of science. (J. Reinke, "Kritische Abstammungslehre", "Wiesner-Festschrift", page 11, Vienna, 1908.) Evidently, then, however little the Theory of Descent may be questioned in our own day, it is desirable to assure ourselves how the case stands, and in particular how far the evidence from fossil plants has grown stronger with time. As regards direct evidence for the derivation of one species from another, there has probably been little advance since Darwin wrote, at least so we must infer from the emphasis laid on the discontinuity of successive fossil species by great systematic authorities like Grand'Eury and Zeiller in their most recent writings. We must either adopt the mutationist views of those authors (referred to in the last section of this essay) or must still rely on Darwin's explanation of the absence of numerous intermediate varieties. The attempts which have been made to trace, in the Tertiary rocks, the evolution of recent species, cannot, owing to the imperfect character of the evidence, be regarded as wholly satisfactory. When we come to groups of a somewhat higher order we have an interesting history of the evolution of a recent family in the work, not yet completed, of Kidston and Gwynne-Vaughan on the fossil Osmundaceae. ("Trans. Royal Soc. Edinburgh", Vol. 45, Part III. 1907, Vol. 46, Part II. 1908, Vol. 46, Part III. 1909.) The authors are able, mainly on anatomical evidence, to trace back this now limited group of Ferns, through the Tertiary and Mesozoic to the Permian, and to show, with great probability, how their structure has been derived from that of early Palaeozoic types. The history of the Ginkgoaceae, now represented only by the isolated maidenhair tree, scarcely known in a wild state, offers another striking example of a family which can be traced with certainty to the older Mesozoic and perhaps further back still. (See Seward and Gowan, "The Maidenhair Tree (Gingko biloba)", "Annals of Botany", Vol. XIV. 1900, page 109; also A. Sprecher "Le Ginkgo biloba", L., Geneva, 1907.) On the wider question of the derivation of the great groups of plants, a very considerable advance has been made, and, so far as the higher plants are concerned, we are now able to form a far better conception than before of the probable course of evolution. This is a matter of phylogeny, and the facts will be considered under that head; our immediate point is that the new knowledge of the relations between the classes of plants in question materially strengthens the case for the theory of descent. The discoveries of the last few years throw light especially on the relation of the Angiosperms to the Gymnosperms, on that of the Seed-plants generally to the Ferns, and on the interrelations between the various classes of the higher Cryptogams. That the fossil record has not done still more for Evolution is due to the fact that it begins too late--a point on which Darwin laid stress ("Origin of Species" (6th edition), page 286.) and which has more recently been elaborated by Poulton. ("Essays on Evolution", pages 46 et seq., Oxford, 1908.) An immense proportion of the whole evolutionary history lies behind the lowest fossiliferous rocks, and the case is worse for plants than for animals, as the record for the former begins, for all practical purposes, much higher up in the rocks. It may be well here to call attention to a question, often overlooked, which has lately been revived by Reinke. (Reinke, loc. cit. page 13.) As all admit, we know nothing of the origin of life; consequently, for all we can tell, it is as probable that life began, on this planet, with many living things, as with one. If the first organic beings were many, they may have been heterogeneous, or at least exposed to different conditions, from their origin; in either case there would have been a number of distinct series from the beginning, and if so we should not be justified in assuming that all organisms are related to one another. There may conceivably be several of the original lines of descent still surviving, or represented among extinct forms--to reverse the remark of a distinguished botanist, there may be several Vegetable Kingdoms! However improbable this may sound, the possibility is one to be borne in mind. That all VASCULAR plants really belong to one stock seems certain, and here the palaeontological record has materially strengthened the case for a monophyletic history. The Bryophyta are not likely to be absolutely distinct, for their sexual organs, and the stomata of the Mosses strongly suggest community of descent with the higher plants; if this be so it no doubt establishes a certain presumption in favour of a common origin for plants generally, for the gap between "Mosses and Ferns" has been regarded as the widest in the Vegetable Kingdom. The direct evidence of consanguinity is however much weaker when we come to the Algae, and it is conceivable (even if improbable) that the higher plants may have had a distinct ancestry (now wholly lost) from the beginning. The question had been raised in Darwin's time, and he referred to it in these words: "No doubt it is possible, as Mr G.H. Lewes has urged, that at the first commencement of life many different forms were evolved; but if so, we may conclude that only a very few have left modified descendants." ("Origin of Species", page 425.) This question, though it deserves attention, does not immediately affect the subject of the palaeontological record of plants, for there can be no reasonable doubt as to the interrelationship of those groups on which the record at present throws light. The past history of plants by no means shows a regular progression from the simple to the complex, but often the contrary. This apparent anomaly is due to two causes. 1. The palaeobotanical record is essentially the story of the successive ascendancy of a series of dominant families, each of which attained its maximum, in organisation as well as in extent, and then sank into comparative obscurity, giving place to other families, which under new conditions were better able to take a leading place. As each family ran its downward course, either its members underwent an actual reduction in structure as they became relegated to herbaceous or perhaps aquatic life (this may have happened with the Horsetails and with Isoetes if derived from Lepidodendreae), or the higher branches of the family were crowded out altogether and only the "poor relations" were able to maintain their position by evading the competition of the ascendant races; this is also illustrated by the history of the Lycopod phylum. In either case there would result a lowering of the type of organisation within the group. 2. The course of real progress is often from the complex to the simple. If, as we shall find some grounds for believing, the Angiosperms came from a type with a flower resembling in its complexity that of Mesozoic "Cycads," almost the whole evolution of the flower in the highest plants has been a process of reduction. The stamen, in particular, has undoubtedly become extremely simplified during evolution; in the most primitive known seed-plants it was a highly compound leaf or pinna; its reduction has gone on in the Conifers and modern Cycads, as well as in the Angiosperms, though in different ways and to a varying extent. The seed offers another striking example; the Palaeozoic seeds (if we leave the seed-like organs of certain Lycopods out of consideration) were always, so far as we know, highly complex structures, with an elaborate vascular system, a pollen-chamber, and often a much-differentiated testa. In the present day such seeds exist only in a few Gymnosperms which retain their ancient characters--in all the higher Spermophytes the structure is very much simplified, and this holds good even in the Coniferae, where there is no countervailing complication of ovary and stigma. Reduction, in fact, is not always, or even generally, the same thing as degeneration. Simplification of parts is one of the most usual means of advance for the organism as a whole. A large proportion of the higher plants are microphyllous in comparison with the highly megaphyllous fern-like forms from which they appear to have been derived. Darwin treated the general question of advance in organisation with much caution, saying: "The geological record... does not extend far enough back, to show with unmistakeable clearness that within the known history of the world organisation has largely advanced." ("Origin of Species", page 308.) Further on (Ibid. page 309.) he gives two standards by which advance may be measured: "We ought not solely to compare the highest members of a class at any two periods... but we ought to compare all the members, high and low, at the two periods." Judged by either standard the Horsetails and Club Mosses of the Carboniferous were higher than those of our own day, and the same is true of the Mesozoic Cycads. There is a general advance in the succession of classes, but not within each class. Darwin's argument that "the inhabitants of the world at each successive period in its history have beaten their predecessors in the race for life, and are, in so far, higher in the scale" ("Origin of Species", page 315.) is unanswerable, but we must remember that "higher in the scale" only means "better adapted to the existing conditions." Darwin points out (Ibid. page 279.) that species have remained unchanged for long periods, probably longer than the periods of modification, and only underwent change when the conditions of their life were altered. Higher organisation, judged by the test of success, is thus purely relative to the changing conditions, a fact of which we have a striking illustration in the sudden incoming of the Angiosperms with all their wonderful floral adaptations to fertilisation by the higher families of Insects. II. PHYLOGENY. The question of phylogeny is really inseparable from that of the truth of the doctrine of evolution, for we cannot have historical evidence that evolution has actually taken place without at the same time having evidence of the course it has followed. As already pointed out, the progress hitherto made has been rather in the way of joining up the great classes of plants than in tracing the descent of particular species or genera of the recent flora. There appears to be a difference in this respect from the Animal record, which tells us so much about the descent of living species, such as the elephant or the horse. The reason for this difference is no doubt to be found in the fact that the later part of the palaeontological record is the most satisfactory in the case of animals and the least so in the case of plants. The Tertiary plant-remains, in the great majority of instances, are impressions of leaves, the conclusions to be drawn from which are highly precarious; until the whole subject of Angiospermous palaeobotany has been reinvestigated, it would be rash to venture on any statements as to the descent of the families of Dicotyledons or Monocotyledons. Our attention will be concentrated on the following questions, all relating to the phylogeny of main groups of plants: i. The Origin of the Angiosperms. ii. The Origin of the Seed-plants. iii. The Origin of the different classes of the Higher Cryptogamia. i. THE ORIGIN OF THE ANGIOSPERMS. The first of these questions has long been the great crux of botanical phylogeny, and until quite recently no light had been thrown upon the difficulty. The Angiosperms are the Flowering Plants, par excellence, and form, beyond comparison, the dominant sub-kingdom in the flora of our own age, including, apart from a few Conifers and Ferns, all the most familiar plants of our fields and gardens, and practically all plants of service to man. All recent work has tended to separate the Angiosperms more widely from the other seed-plants now living, the Gymnosperms. Vast as is the range of organisation presented by the great modern sub-kingdom, embracing forms adapted to every environment, there is yet a marked uniformity in certain points of structure, as in the development of the embryo-sac and its contents, the pollination through the intervention of a stigma, the strange phenomenon of double fertilisation (One sperm fertilising the egg, while the other unites with the embryo-sac nucleus, itself the product of a nuclear fusion, to give rise to a nutritive tissue, the endosperm.), the structure of the stamens, and the arrangement of the parts of the flower. All these points are common to Monocotyledons and Dicotyledons, and separate the Angiosperms collectively from all other plants. In geological history the Angiosperms first appear in the Lower Cretaceous, and by Upper Cretaceous times had already swamped all other vegetation and seized the dominant position which they still hold. Thus they are isolated structurally from the rest of the Vegetable Kingdom, while historically they suddenly appear, almost in full force, and apparently without intermediaries with other groups. To quote Darwin's vigorous words: "The rapid development, as far as we can judge, of all the higher plants within recent geological times is an abominable mystery." ("More Letters of Charles Darwin", Vol. II. page 20, letter to J.D. Hooker, 1879.) A couple of years later he made a bold suggestion (which he only called an "idle thought") to meet this difficulty. He says: "I have been so astonished at the apparently sudden coming in of the higher phanerogams, that I have sometimes fancied that development might have slowly gone on for an immense period in some isolated continent or large island, perhaps near the South Pole." (Ibid, page 26, letter to Hooker, 1881.) This idea of an Angiospermous invasion from some lost southern land has sometimes been revived since, but has not, so far as the writer is aware, been supported by evidence. Light on the problem has come from a different direction. The immense development of plants with the habit of Cycads, during the Mesozoic Period up to the Lower Cretaceous, has long been known. The existing Order Cycadaceae is a small family, with 9 genera and perhaps 100 species, occurring in the tropical and sub-tropical zones of both the Old and New World, but nowhere forming a dominant feature in the vegetation. Some few attain the stature of small trees, while in the majority the stem is short, though often living to a great age. The large pinnate or rarely bipinnate leaves give the Cycads a superficial resemblance in habit to Palms. Recent Cycads are dioecious; throughout the family the male fructification is in the form of a cone, each scale of the cone representing a stamen, and bearing on its lower surface numerous pollen-sacs, grouped in sori like the sporangia of Ferns. In all the genera, except Cycas itself, the female fructifications are likewise cones, each carpel bearing two ovules on its margin. In Cycas, however, no female cone is produced, but the leaf-like carpels, bearing from two to six ovules each, are borne directly on the main stem of the plant in rosettes alternating with those of the ordinary leaves--the most primitive arrangement known in any living seed-plant. The whole Order is relatively primitive, as shown most strikingly in its cryptogamic mode of fertilisation, by means of spermatozoids, which it shares with the maidenhair tree alone, among recent seed-plants. In all the older Mesozoic rocks, from the Trias to the Lower Cretaceous, plants of the Cycad class (Cycadophyta, to use Nathorst's comprehensive name) are extraordinarily abundant in all parts of the world; in fact they were almost as prominent in the flora of those ages as the Dicotyledons are in that of our own day. In habit and to a great extent in anatomy, the Mesozoic Cycadophyta for the most part much resemble the recent Cycadaceae. But, strange to say, it is only in the rarest cases that the fructification has proved to be of the simple type characteristic of the recent family; the vast majority of the abundant fertile specimens yielded by the Mesozoic rocks possess a type of reproductive apparatus far more elaborate than anything known in Cycadaceae or other Gymnosperms. The predominant Mesozoic family, characterised by this advanced reproductive organisation, is known as the Bennettiteae; in habit these plants resembled the more stunted Cycads of the recent flora, but differed from them in the presence of numerous lateral fructifications, like large buds, borne on the stem among the crowded bases of the leaves. The organisation of these fructifications was first worked out on European specimens by Carruthers, Solms-Laubach, Lignier and others, but these observers had only more or less ripe fruits to deal with; the complete structure of the flower has only been elucidated within the last few years by the researches of Wieland on the magnificent American material, derived from the Upper Jurassic and Lower Cretaceous beds of Maryland, Dakota and Wyoming. (G.R. Wieland, "American Fossil Cycads", Carnegie Institution, Washington, 1906.) The word "flower" is used deliberately, for reasons which will be apparent from the following brief description, based on Wieland's observations. The fructification is attached to the stem by a thick stalk, which, in its upper part, bears a large number of spirally arranged bracts, forming collectively a kind of perianth and completely enclosing the essential organs of reproduction. The latter consist of a whorl of stamens, of extremely elaborate structure, surrounding a central cone or receptacle bearing numerous ovules. The stamens resemble the fertile fronds of a fern; they are of a compound, pinnate form, and bear very large numbers of pollen-sacs, each of which is itself a compound structure consisting of a number of compartments in which the pollen was formed. In their lower part the stamens are fused together by their stalks, like the "monadelphous" stamens of a mallow. The numerous ovules borne on the central receptacle are stalked, and are intermixed with sterile scales; the latter are expanded at their outer ends, which are united to form a kind of pericarp or ovary-wall, only interrupted by the protruding micropyles of the ovules. There is thus an approach to the closed pistil of an Angiosperm, but it is evident that the ovules received the pollen directly. The whole fructification is of large size; in the case of Cycadeoidea dacotensis, one of the species investigated by Wieland, the total length, in the bud condition, is about 12 cm., half of which belongs to the peduncle. The general arrangement of the organs is manifestly the same as in a typical Angiospermous flower, with a central pistil, a surrounding whorl of stamens and an enveloping perianth; there is, as we have seen, some approach to the closed ovary of an Angiosperm; another point, first discovered nearly 20 years ago by Solms-Laubach in his investigation of a British species, is that the seed was practically "exalbuminous," its cavity being filled by the large, dicotyledonous embryo, whereas in all known Gymnosperms a large part of the sac is occupied by a nutritive tissue, the prothallus or endosperm; here also we have a condition only met with elsewhere among the higher Flowering Plants. Taking all the characters into account, the indications of affinity between the Mesozoic Cycadophyta and the Angiosperms appear extremely significant, as was recognised by Wieland when he first discovered the hermaphrodite nature of the Bennettitean flower. The Angiosperm with which he specially compared the fossil type was the Tulip tree (Liriodendron) and certainly there is a remarkable analogy with the Magnoliaceous flowers, and with those of related orders such as Ranunculaceae and the Water-lilies. It cannot, of course, be maintained that the Bennettiteae, or any other Mesozoic Cycadophyta at present known, were on the direct line of descent of the Angiosperms, for there are some important points of difference, as, for example, in the great complexity of the stamens, and in the fact that the ovary-wall or pericarp was not formed by the carpels themselves, but by the accompanying sterile scale-leaves. Botanists, since the discovery of the bisexual flowers of the Bennettiteae, have expressed different views as to the nearness of their relation to the higher Flowering Plants, but the points of agreement are so many that it is difficult to resist the conviction that a real relation exists, and that the ancestry of the Angiosperms, so long shrouded in complete obscurity, is to be sought among the great plexus of Cycad-like plants which dominated the flora of the world in Mesozoic times. (On this subject see, in addition to Wieland's great work above cited, F.W. Oliver, "Pteridosperms and Angiosperms", "New Phytologist", Vol. V. 1906; D.H. Scott, "The Flowering Plants of the Mesozoic Age in the Light of Recent Discoveries", "Journal R. Microscop. Soc." 1907, and especially E.A.N. Arber and J. Parkin, "On the Origin of Angiosperms", "Journal Linn. Soc." (Bot.) Vol. XXXVIII. page 29, 1907.) The great complexity of the Bennettitean flower, the earliest known fructification to which the word "flower" can be applied without forcing the sense, renders it probable, as Wieland and others have pointed out, that the evolution of the flower in Angiosperms has consisted essentially in a process of reduction, and that the simplest forms of flower are not to be regarded as the most primitive. The older morphologists generally took the view that such simple flowers were to be explained as reductions from a more perfect type, and this opinion, though abandoned by many later writers, appears likely to be true when we consider the elaboration of floral structure attained among the Mesozoic Cycadophyta, which preceded the Angiosperms in evolution. If, as now seems probable, the Angiosperms were derived from ancestors allied to the Cycads, it would naturally follow that the Dicotyledons were first evolved, for their structure has most in common with that of the Cycadophyta. We should then have to regard the Monocotyledons as a side-line, diverging probably at a very early stage from the main dicotyledonous stock, a view which many botanists have maintained, of late, on other grounds. (See especially Ethel Sargant, "The Reconstruction of a Race of Primitive Angiosperms", "Annals of Botany", Vol. XXII. page 121, 1908.) So far, however, as the palaeontological record shows, the Monocotyledons were little if at all later in their appearance than the Dicotyledons, though always subordinate in numbers. The typical and beautifully preserved Palm-wood from Cretaceous rocks is striking evidence of the early evolution of a characteristic monocotyledonous family. It must be admitted that the whole question of the evolution of Monocotyledons remains to be solved. Accepting, provisionally, the theory of the cycadophytic origin of Angiosperms, it is interesting to see to what further conclusions we are led. The Bennettiteae, at any rate, were still at the gymnospermous level as regards their pollination, for the exposed micropyles of the ovules were in a position to receive the pollen directly, without the intervention of a stigma. It is thus indicated that the Angiosperms sprang from a gymnospermous source, and that the two great phyla of Seed-plants have not been distinct from the first, though no doubt the great majority of known Gymnosperms, especially the Coniferae, represent branch-lines of their own. The stamens of the Bennettiteae are arranged precisely as in an angiospermous flower, but in form and structure they are like the fertile fronds of a Fern, in fact the compound pollen-sacs, or synangia as they are technically called, almost exactly agree with the spore-sacs of a particular family of Ferns--the Marattiaceae, a limited group, now mainly tropical, which was probably more prominent in the later Palaeozoic times than at present. The scaly hairs, or ramenta, which clothe every part of the plant, are also like those of Ferns. It is not likely that the characters in which the Bennettiteae resemble the Ferns came to them directly from ancestors belonging to that class; an extensive group of Seed-plants, the Pteridospermeae, existed in Palaeozoic times and bear evident marks of affinity with the Fern phylum. The fern-like characters so remarkably persistent in the highly organised Cycadophyta of the Mesozoic were in all likelihood derived through the Pteridosperms, plants which show an unmistakable approach to the cycadophytic type. The family Bennettiteae thus presents an extraordinary association of characters, exhibiting, side by side, features which belong to the Angiosperms, the Gymnosperms and the Ferns. ii. ORIGIN OF SEED-PLANTS. The general relation of the gymnospermous Seed-plants to the Higher Cryptogamia was cleared up, independently of fossil evidence, by the brilliant researches of Hofmeister, dating from the middle of the past century. (W. Hofmeister, "On the Germination, Development and Fructification of the Higher Cryptogamia", Ray Society, London, 1862. The original German treatise appeared in 1851.) He showed that "the embryo-sac of the Coniferae may be looked upon as a spore remaining enclosed in its sporangium; the prothallium which it forms does not come to the light." (Ibid. page 438.) He thus determined the homologies on the female side. Recognising, as some previous observers had already done, that the microspores of those Cryptogams in which two kinds of spore are developed, are equivalent to the pollen-grains of the higher plants, he further pointed out that fertilisation "in the Rhizocarpeae and Selaginellae takes place by free spermatozoa, and in the Coniferae by a pollen-tube, in the interior of which spermatozoa are probably formed"--a remarkable instance of prescience, for though spermatozoids have not been found in the Conifers proper, they were demonstrated in the allied groups Cycadaceae and Ginkgo, in 1896, by the Japanese botanists Ikeno and Hirase. A new link was thus established between the Gymnosperms and the Cryptogams. It remained uncertain, however, from which line of Cryptogams the gymnospermous Seed-plants had sprung. The great point of morphological comparison was the presence of two kinds of spore, and this was known to occur in the recent Lycopods and Water-ferns (Rhizocarpeae) and was also found in fossil representatives of the third phylum, that of the Horsetails. As a matter of fact all the three great Cryptogamic classes have found champions to maintain their claim to the ancestry of the Seed-plants, and in every case fossil evidence was called in. For a long time the Lycopods were the favourites, while the Ferns found the least support. The writer remembers, however, in the year 1881, hearing the late Prof. Sachs maintain, in a lecture to his class, that the descent of the Cycads could be traced, not merely from Ferns, but from a definite family of Ferns, the Marattiaceae, a view which, though in a somewhat crude form, anticipated more modern ideas. Williamson appears to have been the first to recognise the presence, in the Carboniferous flora, of plants combining the characters of Ferns and Cycads. (See especially his "Organisation of the Fossil Plants of the Coal-Measures", Part XIII. "Phil. Trans. Royal Soc." 1887 B. page 299.) This conclusion was first reached in the case of the genera Heterangium and Lyginodendron, plants, which with a wholly fern-like habit, were found to unite an anatomical structure holding the balance between that of Ferns and Cycads, Heterangium inclining more to the former and Lyginodendron to the latter. Later researches placed Williamson's original suggestion on a firmer basis, and clearly proved the intermediate nature of these genera, and of a number of others, so far as their vegetative organs were concerned. This stage in our knowledge was marked by the institution of the class Cycadofilices by Potonie in 1897. Nothing, however, was known of the organs of reproduction of the Cycadofilices, until F.W. Oliver, in 1903, identified a fossil seed, Lagenostoma Lomaxi, as belonging to Lyginodendron, the identification depending, in the first instance, on the recognition of an identical form of gland, of very characteristic structure, on the vegetative organs of Lyginodendron and on the cupule enveloping the seed. This evidence was supported by the discovery of a close anatomical agreement in other respects, as well as by constant association between the seed and the plant. (F.W. Oliver and D.H. Scott, "On the Structure of the Palaeozoic Seed, Lagenostoma Lomaxi, etc." "Phil. Trans. Royal Soc." Vol. 197 B. 1904.) The structure of the seed of Lyginodendron, proved to be of the same general type as that of the Cycads, as shown especially by the presence of a pollen-chamber or special cavity for the reception of the pollen-grains, an organ only known in the Cycads and Ginkgo among recent plants. Within a few months after the discovery of the seed of Lyginodendron, Kidston found the large, nut-like seed of a Neuropteris, another fern-like Carboniferous plant, in actual connection with the pinnules of the frond, and since then seeds have been observed on the frond in species of Aneimites and Pecopteris, and a vast body of evidence, direct or indirect, has accumulated, showing that a large proportion of the Palaeozoic plants formerly classed as Ferns were in reality reproduced by seeds of the same type as those of recent Cycadaceae. (A summary of the evidence will be found in the writer's article "On the present position of Palaeozoic Botany", "Progressus Rei Botanicae", 1907, page 139, and "Studies in Fossil Botany", Vol. II. (2nd edition) London, 1909.) At the same time, the anatomical structure, where it is open to investigation, confirms the suggestion given by the habit, and shows that these early seed-bearing plants had a real affinity with Ferns. This conclusion received strong corroboration when Kidston, in 1905, discovered the male organs of Lyginodendron, and showed that they were identical with a fructification of the genus Crossotheca, hitherto regarded as belonging to Marattiaceous Ferns. (Kidston, "On the Microsporangia of the Pteridospermeae, etc." "Phil. Trans. Royal Soc." Vol. 198, B. 1906.) The general conclusion which follows from the various observations alluded to, is that in Palaeozoic times there was a great body of plants (including, as it appears, a large majority of the fossils previously regarded as Ferns) which had attained the rank of Spermophyta, bearing seeds of a Cycadean type on fronds scarcely differing from the vegetative foliage, and in other respects, namely anatomy, habit and the structure of the pollen-bearing organs, retaining many of the characters of Ferns. From this extensive class of plants, to which the name Pteridospermeae has been given, it can scarcely be doubted that the abundant Cycadophyta, of the succeeding Mesozoic period, were derived. This conclusion is of far-reaching significance, for we have already found reason to think that the Angiosperms themselves sprang, in later times, from the Cycadophytic stock; it thus appears that the Fern-phylum, taken in a broad sense, ultimately represents the source from which the main line of descent of the Phanerogams took its rise. It must further be borne in mind that in the Palaeozoic period there existed another group of seed-bearing plants, the Cordaiteae, far more advanced than the Pteridospermeae, and in many respects approaching the Coniferae, which themselves begin to appear in the latest Palaeozoic rocks. The Cordaiteae, while wholly different in habit from the contemporary fern-like Seed-plants, show unmistakable signs of a common origin with them. Not only is there a whole series of forms connecting the anatomical structure of the Cordaiteae with that of the Lyginodendreae among Pteridosperms, but a still more important point is that the seeds of the Cordaiteae, which have long been known, are of the same Cycadean type as those of the Pteridosperms, so that it is not always possible, as yet, to discriminate between the seeds of the two groups. These facts indicate that the same fern-like stock which gave rise to the Cycadophyta and through them, as appears probable, to the Angiosperms, was also the source of the Cordaiteae, which in their turn show manifest affinity with some at least of the Coniferae. Unless the latter are an artificial group, a view which does not commend itself to the writer, it would appear probable that the Gymnosperms generally, as well as the Angiosperms, were derived from an ancient race of Cryptogams, most nearly related to the Ferns. (Some botanists, however, believe that the Coniferae, or some of them, are probably more nearly related to the Lycopods. See Seward and Ford, "The Araucarieae, Recent and Extinct", "Phil. Trans. Royal Soc." Vol. 198 B. 1906.) It may be mentioned here that the small gymnospermous group Gnetales (including the extraordinary West African plant Welwitschia) which were formerly regarded by some authorities as akin to the Equisetales, have recently been referred, on better grounds, to a common origin with the Angiosperms, from the Mesozoic Cycadophyta. The tendency, therefore, of modern work on the palaeontological record of the Seed-plants has been to exalt the importance of the Fern-phylum, which, on present evidence, appears to be that from which the great majority, possibly the whole, of the Spermophyta have been derived. One word of caution, however, is necessary. The Seed-plants are of enormous antiquity; both the Pteridosperms and the more highly organised family Cordaiteae, go back as far in geological history (namely to the Devonian) as the Ferns themselves or any other Vascular Cryptogams. It must therefore be understood that in speaking of the derivation of the Spermophyta from the Fern-phylum, we refer to that phylum at a very early stage, probably earlier than the most ancient period to which our record of land-plants extends. The affinity between the oldest Seed-plants and the Ferns, in the widest sense, seems established, but the common stock from which they actually arose is still unknown; though no doubt nearer to the Ferns than to any other group, it must have differed widely from the Ferns as we now know them, or perhaps even from any which the fossil record has yet revealed to us. iii. THE ORIGIN OF THE HIGHER CRYPTOGAMIA. The Sub-kingdom of the higher Spore-plants, the Cryptogamia possessing a vascular system, was more prominent in early geological periods than at present. It is true that the dominance of the Pteridophyta in Palaeozoic times has been much exaggerated owing to the assumption that everything which looked like a Fern really was a Fern. But, allowing for the fact, now established, that most of the Palaeozoic fern-like plants were already Spermophyta, there remains a vast mass of Cryptogamic forms of that period, and the familiar statement that they formed the main constituent of the Coal-forests still holds good. The three classes, Ferns (Filicales), Horsetails (Equisetales) and Club-mosses (Lycopodiales), under which we now group the Vascular Cryptogams, all extend back in geological history as far as we have any record of the flora of the land; in the Palaeozoic, however, a fourth class, the Sphenophyllales, was present. As regards the early history of the Ferns, which are of special interest from their relation to the Seed-plants, it is impossible to speak quite positively, owing to the difficulty of discriminating between true fossil Ferns and the Pteridosperms which so closely simulated them. The difficulty especially affects the question of the position of Marattiaceous Ferns in the Palaeozoic Floras. This family, now so restricted, was until recently believed to have been one of the most important groups of Palaeozoic plants, especially during later Carboniferous and Permian times. Evidence both from anatomy and from sporangial characters appeared to establish this conclusion. Of late, however, doubts have arisen, owing to the discovery that some supposed members of the Marattiaceae bore seeds, and that a form of fructification previously referred to that family (Crossotheca) was really the pollen-bearing apparatus of a Pteridosperm (Lyginodendron). The question presents much difficulty; though it seems certain that our ideas of the extent of the family in Palaeozoic times will have to be restricted, there is still a decided balance of evidence in favour of the view that a considerable body of Marattiaceous Ferns actually existed. The plants in question were of large size (often arborescent) and highly organised--they represent, in fact, one of the highest developments of the Fern-stock, rather than a primitive type of the class. There was, however, in the Palaeozoic period, a considerable group of comparatively simple Ferns (for which Arber has proposed the collective name Primofilices); the best known of these are referred to the family Botryopterideae, consisting of plants of small or moderate dimensions, with, on the whole, a simple anatomical structure, in certain cases actually simpler than that of any recent Ferns. On the other hand the sporangia of these plants were usually borne on special fertile fronds, a mark of rather high differentiation. This group goes back to the Devonian and includes some of the earliest types of Fern with which we are acquainted. It is probable that the Primofilices (though not the particular family Botryopterideae) represent the stock from which the various families of modern Ferns, already developed in the Mesozoic period, may have sprung. None of the early Ferns show any clear approach to other classes of Vascular Cryptogams; so far as the fossil record affords any evidence, Ferns have always been plants with relatively large and usually compound leaves. There is no indication of their derivation from a microphyllous ancestry, though, as we shall see, there is some slight evidence for the converse hypothesis. Whatever the origin of the Ferns may have been it is hidden in the older rocks. It has, however, been held that certain other Cryptogamic phyla had a common origin with the Ferns. The Equisetales are at present a well-defined group; even in the rich Palaeozoic floras the habit, anatomy and reproductive characters usually render the members of this class unmistakable, in spite of the great development and stature which they then attained. It is interesting, however, to find that in the oldest known representatives of the Equisetales the leaves were highly developed and dichotomously divided, thus differing greatly from the mere scale-leaves of the recent Horsetails, or even from the simple linear leaves of the later Calamites. The early members of the class, in their forked leaves, and in anatomical characters, show an approximation to the Sphenophyllales, which are chiefly represented by the large genus Sphenophyllum, ranging through the Palaeozoic from the Middle Devonian onwards. These were plants with rather slender, ribbed stems, bearing whorls of wedge-shaped or deeply forked leaves, six being the typical number in each whorl. From their weak habit it has been conjectured, with much probability, that they may have been climbing plants, like the scrambling Bedstraws of our hedgerows. The anatomy of the stem is simple and root-like; the cones are remarkable for the fact that each scale or sporophyll is a double structure, consisting of a lower, usually sterile lobe and one or more upper lobes bearing the sporangia; in one species both parts of the sporophyll were fertile. Sphenophyllum was evidently much specialised; the only other known genus is based on an isolated cone, Cheirostrobus, of Lower Carboniferous age, with an extraordinarily complex structure. In this genus especially, but also in the entire group, there is an evident relation to the Equisetales; hence it is of great interest that Nathorst has described, from the Devonian of Bear Island in the Arctic regions, a new genus Pseudobornia, consisting of large plants, remarkable for their highly compound leaves which, when found detached, were taken for the fronds of a Fern. The whorled arrangement of the leaves, and the habit of the plant, suggest affinities either with the Equisetales or the Sphenophyllales; Nathorst makes the genus the type of a new class, the Pseudoborniales. (A.G. Nathorst, "Zur Oberdevonischen Flora der Baren-Insel", "Kongl. Svenska Vetenskaps-Akademiens Handlingar" Bd. 36, No. 3, Stockholm, 1902.) The available data, though still very fragmentary, certainly suggest that both Equisetales and Sphenophyllales may have sprung from a common stock having certain fern-like characters. On the other hand the Sphenophylls, and especially the peculiar genus Cheirostrobus, have in their anatomy a good deal in common with the Lycopods, and of late years they have been regarded as the derivatives of a stock common to that class and the Equisetales. At any rate the characters of the Sphenophyllales and of the new group Pseudoborniales suggest the existence, at a very early period, of a synthetic race of plants, combining the characters of various phyla of the Vascular Cryptogams. It may further be mentioned that the Psilotaceae, an isolated epiphytic family hitherto referred to the Lycopods, have been regarded by several recent authors as the last survivors of the Sphenophyllales, which they resemble both in their anatomy and in the position of their sporangia. The Lycopods, so far as their early history is known, are remarkable rather for their high development in Palaeozoic times than for any indications of a more primitive ancestry. In the recent Flora, two of the four living genera (Excluding Psilotaceae.) (Selaginella and Isoetes) have spores of two kinds, while the other two (Lycopodium and Phylloglossum) are homosporous. Curiously enough, no certain instance of a homosporous Palaeozoic Lycopod has yet been discovered, though well-preserved fructifications are numerous. Wherever the facts have been definitely ascertained, we find two kinds of spore, differentiated quite as sharply as in any living members of the group. Some of the Palaeozoic Lycopods, in fact, went further, and produced bodies of the nature of seeds, some of which were actually regarded, for many years, as the seeds of Gymnosperms. This specially advanced form of fructification goes back at least as far as the Lower Carboniferous, while the oldest known genus of Lycopods, Bothrodendron, which is found in the Devonian, though not seed-bearing, was typically heterosporous, if we may judge from the Coal-measure species. No doubt homosporous Lycopods existed, but the great prevalence of the higher mode of reproduction in days which to us appear ancient, shows how long a course of evolution must have already been passed through before the oldest known members of the group came into being. The other characters of the Palaeozoic Lycopods tell the same tale; most of them attained the stature of trees, with a corresponding elaboration of anatomical structure, and even the herbaceous forms show no special simplicity. It appears from recent work that herbaceous Lycopods, indistinguishable from our recent Selaginellas, already existed in the time of the Coal-measures, while one herbaceous form (Miadesmia) is known to have borne seeds. The utmost that can be said for primitiveness of character in Palaeozoic Lycopods is that the anatomy of the stem, in its primary ground-plan, as distinguished from its secondary growth, was simpler than that of most Lycopodiums and Selaginellas at the present day. There are also some peculiarities in the underground organs (Stigmaria) which suggest the possibility of a somewhat imperfect differentiation between root and stem, but precisely parallel difficulties are met with in the case of the living Selaginellas, and in some degree in species of Lycopodium. In spite of their high development in past ages the Lycopods, recent and fossil, constitute, on the whole, a homogeneous group, and there is little at present to connect them with other phyla. Anatomically some relation to the Sphenophylls is indicated, and perhaps the recent Psilotaceae give some support to this connection, for while their nearest alliance appears to be with the Sphenophylls, they approach the Lycopods in anatomy, habit, and mode of branching. The typically microphyllous character of the Lycopods, and the simple relation between sporangium and sporophyll which obtains throughout the class, have led various botanists to regard them as the most primitive phylum of the Vascular Cryptogams. There is nothing in the fossil record to disprove this view, but neither is there anything to support it, for this class so far as we know is no more ancient than the megaphyllous Cryptogams, and its earliest representatives show no special simplicity. If the indications of affinity with Sphenophylls are of any value the Lycopods are open to suspicion of reduction from a megaphyllous ancestry, but there is no direct palaeontological evidence for such a history. The general conclusions to which we are led by a consideration of the fossil record of the Vascular Cryptogams are still very hypothetical, but may be provisionally stated as follows: The Ferns go back to the earliest known period. In Mesozoic times practically all the existing families had appeared; in the Palaeozoic the class was less extensive than formerly believed, a majority of the supposed Ferns of that age having proved to be seed-bearing plants. The oldest authentic representatives of the Ferns were megaphyllous plants, broadly speaking, of the same type as those of later epochs, though differing much in detail. As far back as the record extends they show no sign of becoming merged with other phyla in any synthetic group. The Equisetales likewise have a long history, and manifestly attained their greatest development in Palaeozoic times. Their oldest forms show an approach to the extinct class Sphenophyllales, which connects them to some extent, by anatomical characters, with the Lycopods. At the same time the oldest Equisetales show a somewhat megaphyllous character, which was more marked in the Devonian Pseudoborniales. Some remote affinity with the Ferns (which has also been upheld on other grounds) may thus be indicated. It is possible that in the Sphenophyllales we may have the much-modified representatives of a very ancient synthetic group. The Lycopods likewise attained their maximum in the Palaeozoic, and show, on the whole, a greater elaboration of structure in their early forms than at any later period, while at the same time maintaining a considerable degree of uniformity in morphological characters throughout their history. The Sphenophyllales are the only other class with which they show any relation; if such a connection existed, the common point of origin must lie exceedingly far back. The fossil record, as at present known, cannot, in the nature of things, throw any direct light on what is perhaps the most disputed question in the morphology of plants--the origin of the alternating generations of the higher Cryptogams and the Spermophyta. At the earliest period to which terrestrial plants have been traced back all the groups of Vascular Cryptogams were in a highly advanced stage of evolution, while innumerable Seed-plants--presumably the descendants of Cryptogamic ancestors--were already flourishing. On the other hand we know practically nothing of Palaeozoic Bryophyta, and the evidence even for their existence at that period cannot be termed conclusive. While there are thus no palaeontological grounds for the hypothesis that the Vascular plants came of a Bryophytic stock, the question of their actual origin remains unsolved. III. NATURAL SELECTION. Hitherto we have considered the palaeontological record of plants in relation to Evolution. The question remains, whether the record throws any light on the theory of which Darwin and Wallace were the authors--that of Natural Selection. The subject is clearly one which must be investigated by other methods than those of the palaeontologist; still there are certain important points involved, on which the palaeontological record appears to bear. One of these points is the supposed distinction between morphological and adaptive characters, on which Nageli, in particular, laid so much stress. The question is a difficult one; it was discussed by Darwin ("Origin of Species" (6th edition), pages 170-176.), who, while showing that the apparent distinction is in part to be explained by our imperfect knowledge of function, recognised the existence of important morphological characters which are not adaptations. The following passage expresses his conclusion. "Thus, as I am inclined to believe, morphological differences, which we consider as important--such as the arrangement of the leaves, the divisions of the flower or of the ovarium, the position of the ovules, etc.--first appeared in many cases as fluctuating variations, which sooner or later became constant through the nature of the organism and of the surrounding conditions, as well as through the inter-crossing of distinct individuals, but not through natural selection; for as these morphological characters do not affect the welfare of the species, any slight deviations in them could not have been governed or accumulated through this latter agency." (Ibid. page 176.) This is a sufficiently liberal concession; Nageli, however, went much further when he said: "I do not know among plants a morphological modification which can be explained on utilitarian principles." (See "More Letters", Vol. II. page 375 (footnote).) If this were true the field of Natural Selection would be so seriously restricted, as to leave the theory only a very limited importance. It can be shown, as the writer believes, that many typical "morphological characters," on which the distinction between great classes of plants is based, were adaptive in origin, and even that their constancy is due to their functional importance. Only one or two cases will be mentioned, where the fossil evidence affects the question. The pollen-tube is one of the most important morphological characters of the Spermophyta as now existing--in fact the name Siphonogama is used by Engler in his classification, as expressing a peculiarly constant character of the Seed-plants. Yet the pollen-tube is a manifest adaptation, following on the adoption of the seed-habit, and serving first to bring the spermatozoids with greater precision to their goal, and ultimately to relieve them of the necessity for independent movement. The pollen-tube is constant because it has proved to be indispensable. In the Palaeozoic Seed-plants there are a number of instances in which the pollen-grains, contained in the pollen-chamber of a seed, are so beautifully preserved that the presence of a group of cells within the grain can be demonstrated; sometimes we can even see how the cell-walls broke down to emit the sperms, and quite lately it is said that the sperms themselves have been recognised. (F.W. Oliver, "On Physostoma elegans, an archaic type of seed from the Palaeozoic Rocks", "Annals of Botany", January, 1909. See also the earlier papers there cited.) In no case, however, is there as yet any satisfactory evidence for the formation of a pollen-tube; it is probable that in these early Seed-plants the pollen-grains remained at about the evolutionary level of the microspores in Pilularia or Selaginella, and discharged their spermatozoids directly, leaving them to find their own way to the female cells. It thus appears that there were once Spermophyta without pollen-tubes. The pollen-tube method ultimately prevailed, becoming a constant "morphological character," for no other reason than because, under the new conditions, it provided a more perfect mechanism for the accomplishment of the act of fertilisation. We have still, in the Cycads and Ginkgo, the transitional case, where the tube remains short, serves mainly as an anchor and water-reservoir, but yet is able, by its slight growth, to give the spermatozoids a "lift" in the right direction. In other Seed-plants the sperms are mere passengers, carried all the way by the pollen-tube; this fact has alone rendered the Angiospermous method of fertilisation through a stigma possible. We may next take the seed itself--the very type of a morphological character. Our fossil record does not go far enough back to tell us the origin of the seed in the Cycadophyta and Pteridosperms (the main line of its development) but some interesting sidelights may be obtained from the Lycopod phylum. In two Palaeozoic genera, as we have seen, seed-like organs are known to have been developed, resembling true seeds in the presence of an integument and of a single functional embryo-sac, as well as in some other points. We will call these organs "seeds" for the sake of shortness. In one genus (Lepidocarpon) the seeds were borne on a cone indistinguishable from that of the ordinary cryptogamic Lepidodendreae, the typical Lycopods of the period, while the seed itself retained much of the detailed structure of the sporangium of that family. In the second genus, Miadesmia, the seed-bearing plant was herbaceous, and much like a recent Selaginella. (See Margaret Benson, "Miadesmia membranacea, a new Palaeozoic Lycopod with a seed-like structure", "Phil. Trans. Royal Soc. Vol." 199, B. 1908.) The seeds of the two genera are differently constructed, and evidently had an independent origin. Here, then, we have seeds arising casually, as it were, at different points among plants which otherwise retain all the characters of their cryptogamic fellows; the seed is not yet a morphological character of importance. To suppose that in these isolated cases the seed sprang into being in obedience to a Law of Advance ("Vervollkommungsprincip"), from which other contemporary Lycopods were exempt, involves us in unnecessary mysticism. On the other hand it is not difficult to see how these seeds may have arisen, as adaptive structures, under the influence of Natural Selection. The seed-like structure afforded protection to the prothallus, and may have enabled the embryo to be launched on the world in greater security. There was further, as we may suppose, a gain in certainty of fertilisation. As the writer has pointed out elsewhere, the chances against the necessary association of the small male with the large female spores must have been enormously great when the cones were borne high up on tall trees. The same difficulty may have existed in the case of the herbaceous Miadesmia, if, as Miss Benson conjectures, it was an epiphyte. One way of solving the problem was for pollination to take place while the megaspore was still on the parent plant, and this is just what the formation of an ovule or seed was likely to secure. The seeds of the Pteridosperms, unlike those of the Lycopod stock, have not yet been found in statu nascendi--in all known cases they were already highly developed organs and far removed from the cryptogamic sporangium. But in two respects we find that these seeds, or some of them, had not yet realised their possibilities. In the seed of Lyginodendron and other cases the micropyle, or orifice of the integument, was not the passage through which the pollen entered; the open neck of the pollen-chamber protruded through the micropyle and itself received the pollen. We have met with an analogous case, at a more advanced stage of evolution, in the Bennettiteae, where the wall of the gynaecium, though otherwise closed, did not provide a stigma to catch the pollen, but allowed the micropyles of the ovules to protrude and receive the pollen in the old gymnospermous fashion. The integument in the one case and the pistil in the other had not yet assumed all the functions to which the organ ultimately became adapted. Again, no Palaeozoic seed has yet been found to contain an embryo, though the preservation is often good enough for it to have been recognised if present. It is probable that the nursing of the embryo had not yet come to be one of the functions of the seed, and that the whole embryonic development was relegated to the germination stage. In these two points, the reception of the pollen by the micropyle and the nursing of the embryo, it appears that many Palaeozoic seeds were imperfect, as compared with the typical seeds of later times. As evolution went on, one function was superadded on another, and it appears impossible to resist the conclusion that the whole differentiation of the seed was a process of adaptation, and consequently governed by Natural Selection, just as much as the specialisation of the rostellum in an Orchid, or of the pappus in a Composite. Did space allow, other examples might be added. We may venture to maintain that the glimpses which the fossil record allows us into early stages in the evolution of organs now of high systematic importance, by no means justify the belief in any essential distinction between morphological and adaptive characters. Another point, closely connected with Darwin's theory, on which the fossil history of plants has been supposed to have some bearing, is the question of Mutation, as opposed to indefinite variation. Arber and Parkin, in their interesting memoir on the Origin of Angiosperms, have suggested calling in Mutation to explain the apparently sudden transition from the cycadean to the angiospermous type of foliage, in late Mesozoic times, though they express themselves with much caution, and point out "a distinct danger that Mutation may become the last resort of the phylogenetically destitute"! The distinguished French palaeobotanists, Grand'Eury (C. Grand'Eury, "Sur les mutations de quelques Plantes fossiles du Terrain houiller". "Comptes Rendus", CXLII. page 25, 1906.) and Zeiller (R. Zeiller "Les Vegetaux fossiles et leurs Enchainements", "Revue du Mois", III. February, 1907.), are of opinion, to quote the words of the latter writer, that the facts of fossil Botany are in agreement with the sudden appearance of new forms, differing by marked characters from those that have given them birth; he adds that these results give more amplitude to this idea of Mutation, extending it to groups of a higher order, and even revealing the existence of discontinuous series between the successive terms of which we yet recognise bonds of filiation. (Loc. cit. page 23.) If Zeiller's opinion should be confirmed, it would no doubt be a serious blow to the Darwinian theory. As Darwin said: "Under a scientific point of view, and as leading to further investigation, but little advantage is gained by believing that new forms are suddenly developed in an inexplicable manner from old and widely different forms, over the old belief in the creation of species from the dust of the earth." ("Origin of Species", page 424.) It most however be pointed out, that such mutations as Zeiller, and to some extent Arber and Parkin, appear to have in view, bridging the gulf between different Orders and Classes, bear no relation to any mutations which have been actually observed, such as the comparatively small changes, of sub-specific value, described by De Vries in the type-case of Oenothera Lamarckiana. The results of palaeobotanical research have undoubtedly tended to fill up gaps in the Natural System of plants--that many such gaps still persist is not surprising; their presence may well serve as an incentive to further research but does not, as it seems to the writer, justify the assumption of changes in the past, wholly without analogy among living organisms. As regards the succession of species, there are no greater authorities than Grand'Eury and Zeiller, and great weight must be attached to their opinion that the evidence from continuous deposits favours a somewhat sudden change from one specific form to another. At the same time it will be well to bear in mind that the subject of the "absence of numerous intermediate varieties in any single formation" was fully discussed by Darwin. ("Origin of Species", pages 275-282, and page 312.); the explanation which he gave may go a long way to account for the facts which recent writers have regarded as favouring the theory of saltatory mutation. The rapid sketch given in the present essay can do no more than call attention to a few salient points, in which the palaeontological records of plants has an evident bearing on the Darwinian theory. At the present day the whole subject of palaeobotany is a study in evolution, and derives its chief inspiration from the ideas of Darwin and Wallace. In return it contributes something to the verification of their teaching; the recent progress of the subject, in spite of the immense difficulties which still remain, has added fresh force to Darwin's statement that "the great leading facts in palaeontology agree admirably with the theory of descent with modification through variation and natural selection." (Ibid. page 313.) XIII. THE INFLUENCE OF ENVIRONMENT ON THE FORMS OF PLANTS. By Georg Klebs, PH.D. Professor of Botany in the University of Heidelberg. The dependence of plants on their environment became the object of scientific research when the phenomena of life were first investigated and physiology took its place as a special branch of science. This occurred in the course of the eighteenth century as the result of the pioneer work of Hales, Duhamel, Ingenhousz, Senebier and others. In the nineteenth century, particularly in the second half, physiology experienced an unprecedented development in that it began to concern itself with the experimental study of nutrition and growth, and with the phenomena associated with stimulus and movement; on the other hand, physiology neglected phenomena connected with the production of form, a department of knowledge which was the province of morphology, a purely descriptive science. It was in the middle of the last century that the growth of comparative morphology and the study of phases of development reached their highest point. The forms of plants appeared to be the expression of their inscrutable inner nature; the stages passed through in the development of the individual were regarded as the outcome of purely internal and hidden laws. The feasibility of experimental inquiry seemed therefore remote. Meanwhile, the recognition of the great importance of such a causal morphology emerged from the researches of the physiologists of that time, more especially from those of Hofmeister (Hofmeister, "Allgemeine Morphologie", Leipzig, 1868, page 579.), and afterwards from the work of Sachs. (Sachs, "Stoff und Form der Pflanzenorgane", Vol. I. 1880; Vol. II. 1882. "Gesammelte Abhandlungen uber Pflanzen-Physiologie", II. Leipzig, 1893.) Hofmeister, in speaking of this line of inquiry, described it as "the most pressing and immediate aim of the investigator to discover to what extent external forces acting on the organism are of importance in determining its form." This advance was the outcome of the influence of that potent force in biology which was created by Darwin's "Origin of Species" (1859). The significance of the splendid conception of the transformation of species was first recognised and discussed by Lamarck (1809); as an explanation of transformation he at once seized upon the idea--an intelligible view--that the external world is the determining factor. Lamarck (Lamarck, "Philosophie zoologique", pages 223-227. Paris, 1809.) endeavoured, more especially, to demonstrate from the behaviour of plants that changes in environment induce change in form which eventually leads to the production of new species. In the case of animals, Lamarck adopted the teleological view that alterations in the environment first lead to alterations in the needs of the organisms, which, as the result of a kind of conscious effort of will, induce useful modifications and even the development of new organs. His work has not exercised any influence on the progress of science: Darwin himself confessed in regard to Lamarck's work--"I got not a fact or idea from it." ("Life and Letters", Vol. II. page 215.) On a mass of incomparably richer and more essential data Darwin based his view of the descent of organisms and gained for it general acceptance; as an explanation of modification he elaborated the ingeniously conceived selection theory. The question of special interest in this connection, namely what is the importance of the influence of the environment, Darwin always answered with some hesitation and caution, indeed with a certain amount of indecision. The fundamental principle underlying his theory is that of general variability as a whole, the nature and extent of which, especially in cultivated organisms, are fully dealt with in his well-known book. (Darwin, "The variation of Animals and Plants under domestication", 2 vols., edition 1, 1868; edition 2, 1875; popular edition 1905.) In regard to the question as to the cause of variability Darwin adopts a consistently mechanical view. He says: "These several considerations alone render it probable that variability of every kind is directly or indirectly caused by changed conditions of life. Or, to put the case under another point of view, if it were possible to expose all the individuals of a species during many generations to absolutely uniform conditions of life, there would be no variability." ("The variation of Animals and Plants" (2nd edition), Vol. II. page 242.) Darwin did not draw further conclusions from this general principle. Variations produced in organisms by the environment are distinguished by Darwin as "the definite" and "the indefinite." (Ibid. II. page 260. See also "Origin of Species" (6th edition), page 6.) The first occur "when all or nearly all the offspring of an individual exposed to certain conditions during several generations are modified in the same manner." Indefinite variation is much more general and a more important factor in the production of new species; as a result of this, single individuals are distinguished from one another by "slight" differences, first in one then in another character. There may also occur, though this is very rare, more marked modifications, "variations which seem to us in our ignorance to arise spontaneously." ("Origin of Species" (6th edition), page 421.) The selection theory demands the further postulate that such changes, "whether extremely slight or strongly marked," are inherited. Darwin was no nearer to an experimental proof of this assumption than to the discovery of the actual cause of variability. It was not until the later years of his life that Darwin was occupied with the "perplexing problem... what causes almost every cultivated plant to vary" ("Life and Letters", Vol. III. page 342.): he began to make experiments on the influence of the soil, but these were soon given up. In the course of the violent controversy which was the outcome of Darwin's work the fundamental principles of his teaching were not advanced by any decisive observations. Among the supporters and opponents, Nageli (Nageli, "Theorie der Abstammungslehre", Munich, 1884; cf. Chapter III.) was one of the few who sought to obtain proofs by experimental methods. His extensive cultural experiments with alpine Hieracia led him to form the opinion that the changes which are induced by an alteration in the food-supply, in climate or in habitat, are not inherited and are therefore of no importance from the point of view of the production of species. And yet Nageli did attribute an important influence to the external world; he believed that adaptations of plants arise as reactions to continuous stimuli, which supply a need and are therefore useful. These opinions, which recall the teleological aspect of Lamarckism, are entirely unsupported by proof. While other far-reaching attempts at an explanation of the theory of descent were formulated both in Nageli's time and afterwards, some in support of, others in opposition to Darwin, the necessity of investigating, from different standpoints, the underlying causes, variability and heredity, was more and more realised. To this category belong the statistical investigations undertaken by Quetelet and Galton, the researches into hybridisation, to which an impetus was given by the re-discovery of the Mendelian law of segregation, as also by the culture experiments on mutating species following the work of de Vries, and lastly the consideration of the question how far variation and heredity are governed by external influences. These latter problems, which are concerned in general with the causes of form-production and form-modification, may be treated in a short summary which falls under two heads, one having reference to the conditions of form-production in single species, the other being concerned with the conditions governing the transformation of species. I. THE INFLUENCE OF EXTERNAL CONDITIONS ON FORM-PRODUCTION IN SINGLE SPECIES. The members of plants, which we express by the terms stem, leaf, flower, etc. are capable of modification within certain limits; since Lamarck's time this power of modification has been brought more or less into relation with the environment. We are concerned not only with the question of experimental demonstration of this relationship, but, more generally, with an examination of the origin of forms, the sequences of stages in development that are governed by recognisable causes. We have to consider the general problem; to study the conditions of all typical as well as of atypic forms, in other words, to found a physiology of form. If we survey the endless variety of plant-forms and consider the highly complex and still little known processes in the interior of cells, and if we remember that the whole of this branch of investigation came into existence only a few decades ago, we are able to grasp the fact that a satisfactory explanation of the factors determining form cannot be discovered all at once. The goal is still far away. We are not concerned now with the controversial question, whether, on the whole, the fundamental processes in the development of form can be recognised by physiological means. A belief in the possibility of this can in any case do no harm. What we may and must attempt is this--to discover points of attack on one side or another, which may enable us by means of experimental methods to come into closer touch with these elusive and difficult problems. While we are forced to admit that there is at present much that is insoluble there remains an inexhaustible supply of problems capable of solution. The object of our investigations is the species; but as regards the question, what is a species, science of to-day takes up a position different from that of Darwin. For him it was the Linnean species which illustrates variation: we now know, thanks to the work of Jordan, de Bary, and particularly to that of de Vries (de Vries, "Die Mutationstheorie", Leipzig, 1901, Vol. I. page 33.), that the Linnean species consists of a large or small number of entities, elementary species. In experimental investigation it is essential that observations be made on a pure species, or, as Johannsen (Johannsen, "Ueber Erblichkeit in Populationen und reinen Linien", Jena, 1903.) says, on a pure "line." What has long been recognised as necessary in the investigation of fungi, bacteria and algae must also be insisted on in the case of flowering plants; we must start with a single individual which is reproduced vegetatively or by strict self-fertilisation. In dioecious plants we must aim at the reproduction of brothers and sisters. We may at the outset take it for granted that a pure species remains the same under similar external conditions; it varies as these vary. IT IS CHARACTERISTIC OF A SPECIES THAT IT ALWAYS EXHIBITS A CONSTANT RELATION TO A PARTICULAR ENVIRONMENT. In the case of two different species, e.g. the hay and anthrax bacilli or two varieties of Campanula with blue and white flowers respectively, a similar environment produces a constant difference. The cause of this is a mystery. According to the modern standpoint, the living cell is a complex chemico-physical system which is regarded as a dynamical system of equilibrium, a conception suggested by Herbert Spencer and which has acquired a constantly increasing importance in the light of modern developments in physical chemistry. The various chemical compounds, proteids, carbohydrates, fats, the whole series of different ferments, etc. occur in the cell in a definite physical arrangement. The two systems of two species must as a matter of fact possess a constant difference, which it is necessary to define by a special term. We say, therefore, that the SPECIFIC STRUCTURE is different. By way of illustrating this provisionally, we may assume that the proteids of the two species possess a constant chemical difference. This conception of specific structure is specially important in its bearing on a further treatment of the subject. In the original cell, eventually also in every cell of a plant, the characters which afterwards become apparent must exist somewhere; they are integral parts of the capabilities or potentialities of specific structure. Thus not only the characters which are exhibited under ordinary conditions in nature, but also many others which become apparent only under special conditions (In this connection I leave out of account, as before, the idea of material carriers of heredity which since the publication of Darwin's Pangenesis hypothesis has been frequently suggested. See my remarks in "Variationen der Bluten", "Pringsheim's Jahrb. Wiss. Bot." 1905, page 298; also Detto, "Biol. Centralbl." 1907, page 81, "Die Erklarbarkeit der Ontogenese durch materielle Anlagen".), are to be included as such potentialities in cells; the conception of specific structure includes the WHOLE OF THE POTENTIALITIES OF A SPECIES; specific structure comprises that which we must always assume without being able to explain it. A relatively simple substance, such as oxalate of lime, is known under a great number of different crystalline forms belonging to different systems (Compare Kohl's work on "Anatomisch-phys. Untersuchungen uber Kalksalze", etc. Marburg, 1889.); these may occur as single crystals, concretions or as concentric sphaerites. The power to assume this variety of form is in some way inherent in the molecular structure, though we cannot, even in this case, explain the necessary connection between structure and crystalline form. These potentialities can only become operative under the influence of external conditions; their stimulation into activity depends on the degree of concentration of the various solutions, on the nature of the particular calcium salt, on the acid or alkaline reactions. Broadly speaking, the plant cell behaves in a similar way. The manifestation of each form, which is inherent as a potentiality in the specific structure, is ultimately to be referred to external conditions. An insight into this connection is, however, rendered exceedingly difficult, often quite impossible, because the environment never directly calls into action the potentialities. Its influence is exerted on what we may call the inner world of the organism, the importance of which increases with the degree of differentiation. The production of form in every plant depends upon processes in the interior of the cells, and the nature of these determines which among the possible characters is to be brought to light. In no single case are we acquainted with the internal process responsible for the production of a particular form. All possible factors may play a part, such as osmotic pressure, permeability of the protoplasm, the degree of concentration of the various chemical substances, etc.; all these factors should be included in the category of INTERNAL CONDITIONS. This inner world appears the more hidden from our ken because it is always represented by a certain definite state, whether we are dealing with a single cell or with a small group of cells. These have been produced from pre-existing cells and they in turn from others; the problem is constantly pushed back through a succession of generations until it becomes identified with that of the origin of species. A way, however, is opened for investigation; experience teaches us that this inner world is not a constant factor: on the contrary, it appears to be very variable. The dependence of VARIABLE INTERNAL on VARIABLE EXTERNAL conditions gives us the key with which research may open the door. In the lower plants this dependence is at once apparent, each cell is directly subject to external influences. In the higher plants with their different organs, these influences were transmitted to cells in course of development along exceedingly complex lines. In the case of the growing-point of a bud, which is capable of producing a complete plant, direct influences play a much less important part than those exerted through other organs, particularly through the roots and leaves, which are essential in nutrition. These correlations, as we may call them, are of the greatest importance as aids to an understanding of form-production. When a bud is produced on a particular part of a plant, it undergoes definite internal modifications induced by the influence of other organs, the activity of which is governed by the environment, and as the result of this it develops along a certain direction; it may, for example, become a flower. The particular direction of development is determined before the rudiment is differentiated and is exerted so strongly that further development ensues without interruption, even though the external conditions vary considerably and exert a positively inimical influence: this produces the impression that development proceeds entirely independently of the outer world. The widespread belief that such independence exists is very premature and at all events unproven. The state of the young rudiment is the outcome of previous influences of the external world communicated through other organs. Experiments show that in certain cases, if the efficiency of roots and leaves as organs concerned with nutrition is interfered with, the production of flowers is affected, and their characters, which are normally very constant, undergo far-reaching modifications. To find the right moment at which to make the necessary alteration in the environment is indeed difficult and in many cases not yet possible. This is especially the case with fertilised eggs, which in a higher degree than buds have acquired, through parental influences, an apparently fixed internal organisation, and this seems to have pre-determined their development. It is, however, highly probable that it will be possible, by influencing the parents, to alter the internal organisation and to switch off development on to other lines. Having made these general observations I will now cite a few of the many facts at our disposal, in order to illustrate the methods and aim of the experimental methods of research. As a matter of convenience I will deal separately with modification of development and with modification of single organs. I. EFFECT OF ENVIRONMENT UPON THE COURSE OF DEVELOPMENT. Every plant, whether an alga or a flowering plant passes, under natural conditions, through a series of developmental stages characteristic of each species, and these consist in a regular sequence of definite forms. It is impossible to form an opinion from mere observation and description as to what inner changes are essential for the production of the several forms. We must endeavour to influence the inner factors by known external conditions in such a way that the individual stages in development are separately controlled and the order of their sequence determined at will by experimental treatment. Such control over the course of development may be gained with special certainty in the case of the lower organisms. With these it is practicable to control the principal conditions of cultivation and to vary them in various ways. By this means it has been demonstrated that each developmental stage depends upon special external conditions, and in cases where our knowledge is sufficient, a particular stage may be obtained at will. In the Green Algae (See Klebs, "Die Bedingung der Fortpflanzung... ", Jena, 1896; also "Jahrb. fur Wiss. Bot." 1898 and 1900; "Probleme der Entwickelung, III." "Biol. Centralbl." 1904, page 452.), as in the case of Fungi, we may classify the stages of development into purely vegetative growth (growth, cell-division, branching), asexual reproduction (formation of zoospores, conidia) and sexual processes (formation of male and female sexual organs). By modifying the external conditions it is possible to induce algae or fungi (Vaucheria, Saprolegnia) to grow continuously for several years or, in the course of a few days, to die after an enormous production of asexual or sexual cells. In some instances even an almost complete stoppage of growth may be caused, reproductive cells being scarcely formed before the organism is again compelled to resort to reproduction. Thus the sequence of the different stages in development can be modified as we may desire. The result of a more thorough investigation of the determining conditions appears to produce at first sight a confused impression of all sorts of possibilities. Even closely allied species exhibit differences in regard to the connection between their development and external conditions. It is especially noteworthy that the same form in development may be produced as the result of very different alterations in the environment. At the same time we can undoubtedly detect a certain unity in the multiplicity of the individual phenomena. If we compare the factors essential for the different stages in development, we see that the question always resolves itself into one of modification of similar conditions common to all life-processes. We should rather have inferred that there exist specific external stimuli for each developmental stage, for instance, certain chemical agencies. Experiments hitherto made support the conclusion that QUANTITATIVE alterations in the general conditions of life produce different types of development. An alga or a fungus grows so long as all the conditions of nutrition remain at a certain optimum for growth. In order to bring about asexual reproduction, e.g. the formation of zoospores, it is sometimes necessary to increase the degree of intensity of external factors; sometimes, on the other hand, these must be reduced in intensity. In the case of many algae a decrease in light-intensity or in the amount of salts in the culture solution, or in the temperature, induces asexual reproduction, while in others, on the contrary, an increase in regard to each of these factors is required to produce the same result. This holds good for the quantitative variations which induce sexual reproduction in algae. The controlling factor is found to be a reduction in the supply of nutritive salts and the exposure of the plants to prolonged illumination or, better still, an increase in the intensity of the light, the efficiency of illumination depending on the consequent formation of organic substances such as carbohydrates. The quantitative alterations of external conditions may be spoken of as releasing stimuli. They produce, in the complex equilibrium of the cell, quantitative modifications in the arrangement and distribution of mass, by means of which other chemical processes are at once set in motion, and finally a new condition of equilibrium is attained. But the commonly expressed view that the environment can as a rule act only as a releasing agent is incorrect, because it overlooks an essential point. The power of a cell to receive stimuli is only acquired as the result of previous nutrition, which has produced a definite condition of concentration of different substances. Quantities are in this case the determining factors. The distribution of quantities is especially important in the sexual reproduction of algae, for which a vigorous production of the materials formed during carbon-assimilation appears to be essential. In the Flowering plants, on the other hand, for reasons already mentioned, the whole problem is more complicated. Investigations on changes in the course of development of fertilised eggs have hitherto been unsuccessful; the difficulty of influencing egg-cells deeply immersed in tissue constitutes a serious obstacle. Other parts of plants are, however, convenient objects of experiment; e.g. the growing apices of buds which serve as cuttings for reproductive purposes, or buds on tubers, runners, rhizomes, etc. A growing apex consists of cells capable of division in which, as in egg-cells, a complete series of latent possibilities of development is embodied. Which of these possibilities becomes effective depends upon the action of the outer world transmitted by organs concerned with nutrition. Of the different stages which a flowering plant passes through in the course of its development we will deal only with one in order to show that, in spite of its great complexity, the problem is, in essentials, equally open to attack in the higher plants and in the simplest organisms. The most important stage in the life of a flowering plant is the transition from purely vegetative growth to sexual reproduction--that is, the production of flowers. In certain cases it can be demonstrated that there is no internal cause, dependent simply on the specific structure, which compels a plant to produce its flowers after a definite period of vegetative growth. (Klebs, "Willkurliche Entwickelungsanderungen", Jena 1903; see also "Probleme der Entwickelung", I. II. "Centralbl." 1904.) One extreme case, that of exceptionally early flowering, has been observed in nature and more often in cultivation. A number of plants under certain conditions are able to flower soon after germination. (Cf. numerous records of this kind by Diels, "Jugendformen und Bluten", Berlin, 1906.) This shortening of the period of development is exhibited in the most striking form in trees, as in the oak (Mobius, "Beitrage zur Lehre von der Fortpflanzung", Jena, 1897, page 89.), flowering seedlings of which have been observed from one to three years old, whereas normally the tree does not flower until it is sixty or eighty years old. Another extreme case is represented by prolonged vegetative growth leading to the complete suppression of flower-production. This result may be obtained with several plants, such as Glechoma, the sugar beet, Digitalis, and others, if they are kept during the winter in a warm, damp atmosphere, and in rich soil; in the following spring or summer they fail to flower. (Klebs, "Willkurliche Aenderungen", etc. Jena, 1903, page 130.) Theoretically, however, experiments are of greater importance in which the production of flowers is inhibited by very favourable conditions of nutrition (Klebs, "Ueber kunstliche Metamorphosen", Stuttgart, 1906, page 115) ("Abh. Naturf. Ges. Halle", XXV.) occurring at the normal flowering period. Even in the case of plants of Sempervivum several years old, which, as is shown by control experiments on precisely similar plants, are on the point of flowering, flowering is rendered impossible if they are forced to very vigorous growth by an abundant supply of water and salts in the spring. Flowering, however, occurs, if such plants are cultivated in relatively dry sandy soil and in the presence of strong light. Careful researches into the conditions of growth have led, in the cases Sempervivum, to the following results: (1) With a strong light and vigorous carbon-assimilation a considerably increased supply of water and nutritive salts produces active vegetative growth. (2) With a vigorous carbon-assimilation in strong light, and a decrease in the supply of water and salts active flower-production is induced. (3) If an average supply of water and salts is given both processes are possible; the intensity of carbon-assimilation determines which of the two is manifested. A diminution in the production of organic substances, particularly of carbohydrates, induces vegetative growth. This can be effected by culture in feeble light or in light deprived of the yellow-red rays: on the other hand, flower-production follows an increase in light-intensity. These results are essentially in agreement with well-known observations on cultivated plants, according to which, the application of much moisture, after a plentiful supply of manure composed of inorganic salts, hinders the flower-production of many vegetables, while a decrease in the supply of water and salts favours flowering. ii. INFLUENCE OF THE ENVIRONMENT ON THE FORM OF SINGLE ORGANS. (A considerable number of observations bearing on this question are given by Goebel in his "Experimentelle Morphologie der Pflanzen", Leipzig, 1908. It is not possible to deal here with the alteration in anatomical structure; cf. Kuster, "Pathologische Pflanzenanatomie", Jena, 1903.) If we look closely into the development of a flowering plant, we notice that in a given species differently formed organs occur in definite positions. In a potato plant colourless runners are formed from the base of the main stem which grow underground and produce tubers at their tips: from a higher level foliage shoots arise nearer the apex. External appearances suggest that both the place of origin and the form of these organs were predetermined in the egg-cell or in the tuber. But it was shown experimentally by the well-known investigator Knight (Knight, "Selection from the Physiological and Horticultural Papers", London, 1841.) that tubers may be developed on the aerial stem in place of foliage shoots. These observations were considerably extended by Vochting. (Vochting, "Ueber die Bildung der Knollen", Cassel, 1887; see also "Bot. Zeit." 1902, 87.) In one kind of potato, germinating tubers were induced to form foliage shoots under the influence of a higher temperature; at a lower temperature they formed tuber-bearing shoots. Many other examples of the conversion of foliage-shoots into runners and rhizomes, or vice versa, have been described by Goebel and others. As in the asexual reproduction of algae quantitative alteration in the amount of moisture, light, temperature, etc. determines whether this or that form of shoot is produced. If the primordia of these organs are exposed to altered conditions of nutrition at a sufficiently early stage a complete substitution of one organ for another is effected. If the rudiment has reached a certain stage in development before it is exposed to these influences, extraordinary intermediate forms are obtained, bearing the characters of both organs. The study of regeneration following injury is of greater importance as regards the problem of the development and place of origin of organs. (Reference may be made to the full summary of results given by Goebel in his "Experimentelle Morphologie", Leipzig and Berlin, 1908, Section IV.) Only in relatively very rare cases is there a complete re-formation of the injured organ itself, as e.g. in the growing-apex. Much more commonly injury leads to the development of complementary formations, it may be the rejuvenescence of a hitherto dormant rudiment, or it may be the formation of such ab initio. In all organs, stems, roots, leaves, as well as inflorescences, this kind of regeneration, which occurs in a great variety of ways according to the species, may be observed on detached pieces of the plant. Cases are also known, such, for example, as the leaves of many plants which readily form roots but not shoots, where a complete regeneration does not occur. The widely spread power of reacting to wounding affords a very valuable means of inducing a fresh development of buds and roots on places where they do not occur in normal circumstances. Injury creates special conditions, but little is known as yet in regard to alterations directly produced in this way. Where the injury consists in the separation of an organ from its normal connections, the factors concerned are more comprehensible. A detached leaf, e.g., is at once cut off from a supply of water and salts, and is deprived of the means of getting rid of organic substances which it produces; the result is a considerable alteration in the degree of concentration. No experimental investigation on these lines has yet been made. Our ignorance has often led to the view that we are dealing with a force whose specific quality is the restitution of the parts lost by operation; the proof, therefore, that in certain cases a similar production of new roots or buds may be induced without previous injury and simply by a change in external conditions assumes an importance. (Klebs, "Willkurliche Entwickelung", page 100; also, "Probleme der Entwickelung", "Biol. Centralbl." 1904, page 610.) A specially striking phenomenon of regeneration, exhibited also by uninjured plants, is afforded by polarity, which was discovered by Vochting. (See the classic work of Vochting, "Ueber Organbildung im Pflanzenreich", I. Bonn, 1888; also "Bot. Zeit." 1906, page 101; cf. Goebel, "Experimentelle Morphologie", Leipzig and Berlin, 1908, Section V, Polaritat.) It is found, for example, that roots are formed from the base of a detached piece of stem and shoots from the apex. Within the limits of this essay it is impossible to go into this difficult question; it is, however, important from the point of view of our general survey to emphasise the fact that the physiological distinctions between base and apex of pieces of stem are only of a quantitative kind, that is, they consist in the inhibition of certain phenomena or in favouring them. As a matter of fact roots may be produced from the apices of willows and cuttings of other plants; the distinction is thus obliterated under the influence of environment. The fixed polarity of cuttings from full grown stems cannot be destroyed; it is the expression of previous development. Vochting speaks of polarity as a fixed inherited character. This is an unconvincing conclusion, as nothing can be deduced from our present knowledge as to the causes which led up to polarity. We know that the fertilised egg, like the embryo, is fixed at one end by which it hangs freely in the embryo-sac and afterwards in the endosperm. From the first, therefore, the two ends have different natures, and these are revealed in the differentiation into root-apex and stem-apex. A definite direction in the flow of food-substances is correlated with this arrangement, and this eventually leads to a polarity in the tissues. This view requires experimental proof, which in the case of the egg-cells of flowering plants hardly appears possible; but it derives considerable support from the fact that in herbaceous plants, e.g. Sempervivum (Klebs, "Variationen der Bluten", "Jahrb. Wiss. Bot." 1905, page 260.), rosettes or flower-shoots are formed in response to external conditions at the base, in the middle, or at the apex of the stem, so that polarity as it occurs under normal conditions cannot be the result of unalterable hereditary factors. On the other hand, the lower plants should furnish decisive evidence on this question, and the experiments of Stahl, Winkler, Kniep, and others indicate the right method of attacking the problem. The relation of leaf-form to environment has often been investigated and is well known. The leaves of bog and water plants (Cf.Goebel, loc. cit. chapter II.; also Gluck, "Untersuchungen uber Wasser- und Sumpfgewachse", Jena, Vols. I.-II. 1905-06.) afford the most striking examples of modifications: according as they are grown in water, moist or dry air, the form of the species characteristic of the particular habitat is produced, since the stems are also modified. To the same group of phenomena belongs the modification of the forms of leaves and stems in plants on transplantation from the plains to the mountains (Bonnier, "Recherches sur l'Anatomie experimentale des Vegetaux", Corbeil, 1895.) or vice versa. Such variations are by no means isolated examples. All plants exhibit a definite alteration in form as the result of prolonged cultivation in moist or dry air, in strong or feeble light, or in darkness, or in salt solutions of different composition and strength. Every individual which is exposed to definite combinations of external factors exhibits eventually the same type of modification. This is the type of variation which Darwin termed "definite." It is easy to realise that indefinite or fluctuating variations belong essentially to the same class of phenomena; both are reactions to changes in environment. In the production of individual variations two different influences undoubtedly cooperate. One set of variations is caused by different external conditions, during the production, either of sexual cells or of vegetative primordia; another set is the result of varying external conditions during the development of the embryo into an adult plant. The two sets of influences cannot as yet be sharply differentiated. If, for purposes of vegetative reproduction, we select pieces of the same parent-plant of a pure species, the second type of variation predominates. Individual fluctuations depend essentially in such cases on small variations in environment during development. These relations must be borne in mind if we wish to understand the results of statistical methods. Since the work of Quetelet, Galton, and others the statistical examination of individual differences in animals and plants has become a special science, which is primarily based on the consideration that the application of the theory of probability renders possible mathematical statement and control of the results. The facts show that any character, size of leaf, length of stem, the number of members in a flower, etc. do not vary haphazard but in a very regular manner. In most cases it is found that there is a value which occurs most commonly, the average or medium value, from which the larger and smaller deviations, the so-called plus and minus variations fall away in a continuous series and end in a limiting value. In the simpler cases a falling off occurs equally on both sides of the curve; the curve constructed from such data agrees very closely with the Gaussian curve of error. In more complicated cases irregular curves of different kinds are obtained which may be calculated on certain suppositions. The regular fluctuations about a mean according to the rule of probability is often attributed to some law underlying variability. (de Vries, "Mutationstheorie", Vol. I. page 35, Leipzig, 1901.) But there is no such law which compels a plant to vary in a particular manner. Every experimental investigation shows, as we have already remarked, that the fluctuation of characters depends on fluctuation in the external factors. The applicability of the method of probability follows from the fact that the numerous individuals of a species are influenced by a limited number of variable conditions. (Klebs, "Willkurl. Ent." Jena, 1903, page 141.) As each of these conditions includes within certain limits all possible values and exhibits all possible combinations, it follows that, according to the rules of probability, there must be a mean value, about which the larger and smaller deviations are distributed. Any character will be found to have the mean value which corresponds with that combination of determining factors which occurs most frequently. Deviations towards plus and minus values will be correspondingly produced by rarer conditions. A conclusion of fundamental importance may be drawn from this conception, which is, to a certain extent, supported by experimental investigation. (Klebs, "Studien uber Variation", "Arch. fur Entw." 1907.) There is no normal curve for a particular CHARACTER, there is only a curve for the varying combinations of conditions occurring in nature or under cultivation. Under other conditions entirely different curves may be obtained with other variants as a mean value. If, for example, under ordinary conditions the number 10 is the most frequent variant for the stamens of Sedum spectabile, in special circumstances (red light) this is replaced by the number 5. The more accurately we know the conditions for a particular form or number, and are able to reproduce it by experiment, the nearer we are to achieving our aim of rendering a particular variation impossible or of making it dominant. In addition to the individual variations of a species, more pronounced fluctuations occur relatively rarely and sporadically which are spoken of as "single variations," or if specially striking as abnormalities or monstrosities. These forms have long attracted the attention of morphologists; a large number of observations of this kind are given in the handbooks of Masters (Masters, "Vegetable Teratology", London, 1869.) and Penzig (Penzig, "Pflanzen-Teratologie", Vols I. and II. Genua, 1890-94.) These variations, which used to be regarded as curiosities, have now assumed considerable importance in connection with the causes of form-development. They also possess special interest in relation to the question of heredity, a subject which does not at present concern us, as such deviations from normal development undoubtedly arise as individual variations induced by the influence of environment. Abnormal developments of all kinds in stems, leaves, and flowers, may be produced by parasites, insects, or fungi. They may also be induced by injury, as Blaringhem (Blaringhem, "Mutation et traumatismes", Paris, 1907.) has more particularly demonstrated, which, by cutting away the leading shoots of branches in an early stage of development, caused fasciation, torsion, anomalous flowers, etc. The experiments of Blaringhem point to the probability that disturbances in the conditions of food-supply consequent on injury are the cause of the production of monstrosities. This is certainly the case in my experiments with species of Sempervivum (Klebs, "Kunstliche Metamorphosen", Stuttgart, 1906.); individuals, which at first formed normal flowers, produced a great variety of abnormalities as the result of changes in nutrition, we may call to mind the fact that the formation of inflorescences occurs normally when a vigorous production of organic compounds, such as starch, sugar, etc. follows a diminution in the supply of mineral salts. On the other hand, the development of inflorescences is entirely suppressed if, at a suitable moment before the actual foundations have been laid, water and mineral salts are supplied to the roots. If, during the week when the inflorescence has just been laid down and is growing very slowly, the supply of water and salts is increased, the internal conditions of the cells are essentially changed. At a later stage, after the elongation of the inflorescence, rosettes of leaves are produced instead of flowers, and structures intermediate between the two kinds of organs; a number of peculiar plant-forms are thus obtained (Cf. Lotsy, "Vorlesungen uber Deszendenztheorien", Vol. II. pl. 3, Jena, 1908.) Abnormalities in the greatest variety are produced in flowers by varying the time at which the stimulus is applied, and by the cooperation of other factors such as temperature, darkness, etc. In number and arrangement the several floral members vary within wide limits; sepals, petals, stamens, and carpels are altered in form and colour, a transformation of stamens to carpels and from carpels to stamens occurs in varying degrees. The majority of the deviations observed had not previously been seen either under natural conditions or in cultivation; they were first brought to light through the influence of external factors. Such transformations of flowers become apparent at a time, which is separated by about two months from the period at which the particular cause began to act. There is, therefore, no close connection between the appearance of the modifications and the external conditions which prevail at the moment. When we are ignorant of the causes which are operative so long before the results are seen, we gain the impression that such variations as occur are spontaneous or autonomous expressions of the inner nature of the plant. It is much more likely that, as in Sempervivum, they were originally produced by an external stimulus which had previously reached the sexual cells or the young embryo. In any case abnormalities of this kind appear to be of a special type as compared with ordinary fluctuating variations. Darwin pointed out this difference; Bateson (Bateson, "Materials for the study of Variation", London, 1894, page 5.) has attempted to make the distinction sharper, at the same time emphasising its importance in heredity. Bateson applies the term CONTINUOUS to small variations connected with one another by transitional stages, while those which are more striking and characterised from the first by a certain completeness, he names DISCONTINUOUS. He drew attention to a great difficulty which stands in the way of Lamarck's hypothesis, as also of Darwin's view. "According to both theories, specific diversity of form is consequent upon diversity of environment, and diversity of environment is thus the ultimate measure of diversity of specific form. Here then we meet the difficulty that diverse environments often shade into each other insensibly and form a continuous series, whereas the Specific Forms of life which are subject to them on the whole form a Discontinuous Series." This difficulty is, however, not of fundamental importance as well authenticated facts have been adduced showing that by alteration of the environment discontinuous variations, such as alterations in the number and form of members of a flower, may be produced. We can as yet no more explain how this happens than we can explain the existence of continuous variations. We can only assert that both kinds of variation arise in response to quantitative alterations in external conditions. The question as to which kind of variation is produced depends on the greater or less degree of alteration; it is correlated with the state of the particular cells at the moment. In this short sketch it is only possible to deal superficially with a small part of the subject. It has been clearly shown that in view of the general dependence of development on the factors of the environment a number of problems are ready for experimental treatment. One must, however, not forget that the science of the physiology of form has not progressed beyond its initial stages. Just now our first duty is to demonstrate the dependence on external factors in as many forms of plants as possible, in order to obtain a more thorough control of all the different plant-forms. The problem is not only to produce at will (and independently of their normal mode of life) forms which occur in nature, but also to stimulate into operation potentialities which necessarily lie dormant under the conditions which prevail in nature. The constitution of a species is much richer in possibilities of development than would appear to be the case under normal conditions. It remains for man to stimulate into activity all the potentialities. But the control of plant-form is only a preliminary step--the foundation stones on which to erect a coherent scientific structure. We must discover what are the internal processes in the cell produced by external factors, which as a necessary consequence result in the appearance of a definite form. We are here brought into contact with the most obscure problem of life. Progress can only be made pari passu with progress in physics and chemistry, and with the growth of our knowledge of nutrition, growth, etc. Let us take one of the simplest cases--an alteration in form. A cylindrical cell of the alga Stigeoclonium assumes, as Livingstone (Livingstone, "On the nature of the stimulus which causes the change of form, etc." "Botanical Gazette", XXX. 1900; also XXXII. 1901.) has shown, a spherical form when the osmotic pressure of the culture fluid is increased; or a spore of Mucor, which, in a sugar solution grows into a branched filament, in the presence of a small quantity of acid (hydrogen ions) becomes a comparatively large sphere. (Ritter, "Ueber Kugelhefe, etc." "Ber. bot. Gesell." Berlin, XXV. page 255, 1907.) In both cases there has undoubtedly been an alteration in the osmotic pressure of the cell-sap, but this does not suffice to explain the alteration in form, since the unknown alterations, which are induced in the protoplasm, must in their turn influence the cell-membrane. In the case of the very much more complex alterations in form, such as we encounter in the course of development of plants, there do not appear to be any clues which lead us to a deeper insight into the phenomena. Nevertheless we continue the attempt, seeking with the help of any available hypothesis for points of attack, which may enable us to acquire a more complete mastery of physiological methods. To quote a single example; I may put the question, what internal changes produce a transition from vegetative growth to sexual reproduction? The facts, which are as clearly established from the lower as for the higher plants, teach us that quantitative alteration in the environment produces such a transition. This suggests the conclusion that quantitative internal changes in the cells, and with them disturbances in the degree of concentration, are induced, through which the chemical reactions are led in the direction of sexual reproduction. An increase in the production of organic substances in the presence of light, chiefly of the carbohydrates, with a simultaneous decrease in the amount of inorganic salts and water, are the cause of the disturbance and at the same time of the alteration in the direction of development. Possibly indeed mineral salts as such are not in question, but only in the form of other organic combinations, particularly proteid material, so that we are concerned with an alteration in the relation of the carbohydrates and proteids. The difficulties of such researches are very great because the methods are not yet sufficiently exact to demonstrate the frequently small quantitative differences in chemical composition. Questions relating to the enzymes, which are of the greatest importance in all these life-processes, are especially complicated. In any case it is the necessary result of such an hypothesis that we must employ chemical methods of investigation in dealing with problems connected with the physiology of form. II. INFLUENCE OF ENVIRONMENT ON THE TRANSFORMATION OF SPECIES. The study of the physiology of form-development in a pure species has already yielded results and makes slow but sure progress. The physiology of the possibility of the transformation of one species into another is based, as yet, rather on pious hope than on accomplished fact. From the first it appeared to be hopeless to investigate physiologically the origin of Linnean species and at the same time that of the natural system, an aim which Darwin had before him in his enduring work. The historical sequence of events, of which an organism is the expression, can only be treated hypothetically with the help of facts supplied by comparative morphology, the history of development, geographical distribution, and palaeontology. (See Lotsy, "Vorlesungen" (Jena, I. 1906, II. 1908), for summary of the facts.) A glance at the controversy which is going on today in regard to different hypotheses shows that the same material may lead different investigators to form entirely different opinions. Our ultimate aim is to find a solution of the problem as to the cause of the origin of species. Indeed such attempts are now being made: they are justified by the fact that under cultivation new and permanent strains are produced; the fundamental importance of this was first grasped by Darwin. New points of view in regard to these lines of inquiry have been adopted by H. de Vries who has succeeded in obtaining from Oenothera Lamarckiana a number of constant "elementary" species. Even if it is demonstrated that he was simply dealing with the complex splitting up of a hybrid (Bateson, "Reports to the Evolution Committee of the Royal Society", London, 1902; cf. also Lotsy, "Vorlesungen", Vol. I. page 234.), the facts adduced in no sense lose their very great value. We must look at the problem in its simplest form; we find it in every case where a new race differs essentially from the original type in a single character only; for example, in the colour of the flowers or in the petalody of the stamens (doubling of flowers). In this connection we must keep in view the fact that every visible character in a plant is the resultant of the cooperation of specific structure, with its various potentialities, and the influence of the environment. We know, that in a pure species all characters vary, that a blue-flowering Campanula or a red Sempervivum can be converted by experiment into white-flowering forms, that a transformation of stamens into petals may be caused by fungi or by the influence of changed conditions of nutrition, or that plants in dry and poor soil become dwarfed. But so far as the experiments justify a conclusion, it would appear that such alterations are not inherited by the offspring. Like all other variations they appear only so long as special conditions prevail in the surroundings. It has been shown that the case is quite different as regards the white-flowering, double or dwarf races, because these retain their characters when cultivated under practically identical conditions, and side by side with the blue, single-flowering or tall races. The problem may therefore be stated thus: how can a character, which appears in the one case only under the strictly limited conditions of the experiment, in other cases become apparent under the very much wider conditions of ordinary cultivation? If a character appears, in these circumstances, in the case of all individuals, we then speak of constant races. In such simple cases the essential point is not the creation of a new character but rather an ALTERATION OF THIS CHARACTER IN ACCORDANCE WITH THE ENVIRONMENT. In the examples mentioned the modified character in the simple varieties (or a number of characters in elementary species) appears more or less suddenly and is constant in the above sense. The result is what de Vries has termed a Mutation. In this connection we must bear in mind the fact that no difference, recognisable externally, need exist between individual variation and mutation. Even the most minute quantitative difference between two plants may be of specific value if it is preserved under similar external conditions during many successive generations. We do not know how this happens. We may state the problem in other terms; by saying that the specific structure must be altered. It is possible, to some extent, to explain this sudden alteration, if we regard it as a chemical alteration of structure either in the specific qualities of the proteids or of the unknown carriers of life. In the case of many organic compounds their morphological characters (the physical condition, crystalline form, etc.) are at once changed by alteration of atomic relations or by incorporation of new radicals. (For instance ethylchloride (C2H5Cl) is a gas at 21 deg C., ethylenechloride (C2H4Cl2) a fluid boiling at 84 deg C., beta trichlorethane (C2H3Cl3) a fluid boiling at 113 deg C., perchlorethane (C2Cl6) a crystalline substance. Klebs, ("Willkurliche Entwickelungsanderungen" page 158.) Much more important, however, would be an answer to the question, whether an individual variation can be converted experimentally into an inherited character--a mutation in de Vries's sense. In all circumstances we may recognise as a guiding principle the assumption adopted by Lamarck, Darwin, and many others, that the inheritance of any one character, or in more general terms, the transformation of one species into another, is, in the last instance, to be referred to a change in the environment. From a causal-mechanical point of view it is not a priori conceivable that one species can ever become changed into another so long as external conditions remain constant. The inner structure of a species must be essentially altered by external influences. Two methods of experimental research may be adopted, the effect of crossing distinct species and, secondly, the effect of definite factors of the environment. The subject of hybridisation is dealt with in another part of this essay. It is enough to refer here to the most important fact, that as the result of combinations of characters of different species new and constant forms are produced. Further, Tschermack, Bateson and others have demonstrated the possibility that hitherto unknown inheritable characters may be produced by hybridisation. The other method of producing constant races by the influence of special external conditions has often been employed. The sporeless races of Bacteria and Yeasts (Cf. Detto, "Die Theorie der direkten Anpassung... ", pages 98 et seq., Jena, 1904; see also Lotsy, "Vorlesungen", II. pages 636 et seq., where other similar cases are described.) are well known, in which an internal alteration of the cells is induced by the influence of poison or higher temperature, so that the power of producing spores even under normal conditions appears to be lost. A similar state of things is found in some races which under certain definite conditions lose their colour or their virulence. Among the phanerogams the investigations of Schubler on cereals afford parallel cases, in which the influence of a northern climate produces individuals which ripen their seeds early; these seeds produce plants which seed early in southern countries. Analogous results were obtained by Cieslar in his experiments; seeds of conifers from the Alps when planted in the plains produced plants of slow growth and small diameter. All these observations are of considerable interest theoretically; they show that the action of environment certainly induces such internal changes, and that these are transmitted to the next generation. But as regards the main question, whether constant races may be obtained by this means, the experiments cannot as yet supply a definite answer. In phanerogams, the influence very soon dies out in succeeding generations; in the case of bacteria, in which it is only a question of the loss of a character it is relatively easy for this to reappear. It is not impossible, that in all such cases there is a material hanging-on of certain internal conditions, in consequence of which the modification of the character persists for a time in the descendants, although the original external conditions are no longer present. Thus a slow dying-out of the effect of a stimulus was seen in my experiments on Veronica chamaedrys. (Klebs, "Kunstliche Metamorphosen", Stuttgart, 1906, page 132.) During the cultivation of an artificially modified inflorescence I obtained a race showing modifications in different directions, among which twisting was especially conspicuous. This plant, however, does not behave as the twisted race of Dipsacus isolated by de Vries (de Vries, "Mutationstheorie", Vol. II. Leipzig, 1903, page 573.), which produced each year a definite percentage of twisted individuals. In the vegetative reproduction of this Veronica the torsion appeared in the first, also in the second and third year, but with diminishing intensity. In spite of good cultivation this character has apparently now disappeared; it disappeared still more quickly in seedlings. In another character of the same Veronica chamaedrys the influence of the environment was stronger. The transformation of the inflorescences to foliage-shoots formed the starting-point; it occurred only under narrowly defined conditions, namely on cultivation as a cutting in moist air and on removal of all other leaf-buds. In the majority (7/10) of the plants obtained from the transformed shoots, the modification appeared in the following year without any interference. Of the three plants which were under observation several years the first lost the character in a short time, while the two others still retain it, after vegetative propagation, in varying degrees. The same character occurs also in some of the seedlings; but anything approaching a constant race has not been produced. Another means of producing new races has been attempted by Blaringhem. (Blaringhem, "Mutation et Traumatisme", Paris, 1907.) On removing at an early stage the main shoots of different plants he observed various abnormalities in the newly formed basal shoots. From the seeds of such plants he obtained races, a large percentage of which exhibited these abnormalities. Starting from a male Maize plant with a fasciated inflorescence, on which a proportion of the flowers had become male, a new race was bred in which hermaphrodite flowers were frequently produced. In the same way Blaringhem obtained, among other similar results, a race of barley with branched ears. These races, however, behaved in essentials like those which have been demonstrated by de Vries to be inconstant, e.g. Trifolium pratense quinquefolium and others. The abnormality appears in a proportion of the individuals and only under very special conditions. It must be remembered too that Blaringhem worked with old cultivated plants, which from the first had been disposed to split into a great variety of races. It is possible, but difficult to prove, that injury contributed to this result. A third method has been adopted by MacDougal (MacDougal, "Heredity and Origin of species", "Monist", 1906; "Report of department of botanical research", "Fifth Year-book of the Carnegie Institution of Washington", page 119, 1907.) who injected strong (10 percent) sugar solution or weak solutions of calcium nitrate and zinc sulphate into young carpels of different plants. From the seeds of a plant of Raimannia odorata the carpels of which had been thus treated he obtained several plants distinguished from the parent-forms by the absence of hairs and by distinct forms of leaves. Further examination showed that he had here to do with a new elementary species. MacDougal also obtained a more or less distinct mutant of Oenothera biennis. We cannot as yet form an opinion as to how far the effect is due to the wound or to the injection of fluid as such, or to its chemical properties. This, however, is not so essential as to decide whether the mutant stands in any relation to the influence of external factors. It is at any rate very important that this kind of investigation should be carried further. If it could be shown that new and inherited races were obtained by MacDougal's method, it would be safe to conclude that the same end might be gained by altering the conditions of the food-stuff conducted to the sexual cells. New races or elementary species, however, arise without wounding or injection. This at once raises the much discussed question, how far garden-cultivation has led to the creation of new races? Contrary to the opinion expressed by Darwin and others, de Vries ("Mutationstheorie", Vol. I. pages 412 et seq.) tried to show that garden-races have been produced only from spontaneous types which occur in a wild state or from sub-races, which the breeder has accidentally discovered but not originated. In a small number of cases only has de Vries adduced definite proof. On the other side we have the work of Korschinsky (Korschinsky, "Heterogenesis und Evolution", "Flora", 1901.) which shows that whole series of garden-races have made their appearance only after years of cultivation. In the majority of races we are entirely ignorant of their origin. It is, however, a fact that if a plant is removed from natural conditions into cultivation, a well-marked variation occurs. The well-known plant-breeder L. de Vilmorin (L. de Vilmorin, "Notices sur l'amelioration des plantes", Paris, 1886, page 36.), speaking from his own experience, states that a plant is induced to "affoler," that is to exhibit all possible variations from which the breeder may make a further selection only after cultivation for several generations. The effect of cultivation was particularly striking in Veronica chamaedrys (Klebs, "Kunstliche Metamorphosen", Stuttgart, 1906, page 152.) which, in spite of its wide distribution in nature, varies very little. After a few years of cultivation this "good" and constant species becomes highly variable. The specimens on which the experiments were made were three modified inflorescence cuttings, the parent-plants of which certainly exhibited no striking abnormalities. In a short time many hitherto latent potentialities became apparent, so that characters, never previously observed, or at least very rarely, were exhibited, such as scattered leaf-arrangement, torsion, terminal or branched inflorescences, the conversion of the inflorescence into foliage-shoots, every conceivable alteration in the colour of flowers, the assumption of a green colour by parts of the flowers, the proliferation of flowers. All this points to some disturbance in the species resulting from methods of cultivation. It has, however, not yet been possible to produce constant races with any one of these modified characters. But variations appeared among the seedlings, some of which, e.g. yellow variegation, were not inheritable, while others have proved constant. This holds good, so far as we know at present, for a small rose-coloured form which is to be reckoned as a mutation. Thus the prospect of producing new races by cultivation appears to be full of promise. So long as the view is held that good nourishment, i.e. a plentiful supply of water and salts, constitutes the essential characteristic of garden-cultivation, we can hardly conceive that new mutations can be thus produced. But perhaps the view here put forward in regard to the production of form throws new light on this puzzling problem. Good manuring is in the highest degree favourable to vegetative growth, but is in no way equally favourable to the formation of flowers. The constantly repeated expression, good or favourable nourishment, is not only vague but misleading, because circumstances favourable to growth differ from those which promote reproduction; for the production of every form there are certain favourable conditions of nourishment, which may be defined for each species. Experience shows that, within definite and often very wide limits, it does not depend upon the ABSOLUTE AMOUNT of the various food substances, but upon their respective degrees of concentration. As we have already stated, the production of flowers follows a relative increase in the amount of carbohydrates formed in the presence of light, as compared with the inorganic salts on which the formation of albuminous substances depends. (Klebs, "Kunstliche Metamorphosen", page 117.) The various modifications of flowers are due to the fact that a relatively too strong solution of salts is supplied to the rudiments of these organs. As a general rule every plant form depends upon a certain relation between the different chemical substances in the cells and is modified by an alteration of that relation. During long cultivation under conditions which vary in very different degrees, such as moisture, the amount of salts, light intensity, temperature, oxygen, it is possible that sudden and special disturbances in the relations of the cell substances have a directive influence on the inner organisation of the sexual cells, so that not only inconstant but also constant varieties will be formed. Definite proof in support of this view has not yet been furnished, and we must admit that the question as to the cause of heredity remains, fundamentally, as far from solution as it was in Darwin's time. As the result of the work of many investigators, particularly de Vries, the problem is constantly becoming clearer and more definite. The penetration into this most difficult and therefore most interesting problem of life and the creation by experiment of new races or elementary species are no longer beyond the region of possibility. XIV. EXPERIMENTAL STUDY OF THE INFLUENCE OF ENVIRONMENT ON ANIMALS. By Jacques Loeb, M.D. Professor of Physiology in the University of California. I. INTRODUCTORY REMARKS. What the biologist calls the natural environment of an animal is from a physical point of view a rather rigid combination of definite forces. It is obvious that by a purposeful and systematic variation of these and by the application of other forces in the laboratory, results must be obtainable which do not appear in the natural environment. This is the reasoning underlying the modern development of the study of the effects of environment upon animal life. It was perhaps not the least important of Darwin's services to science that the boldness of his conceptions gave to the experimental biologist courage to enter upon the attempt of controlling at will the life-phenomena of animals, and of bringing about effects which cannot be expected in Nature. The systematic physico-chemical analysis of the effect of outside forces upon the form and reactions of animals is also our only means of unravelling the mechanism of heredity beyond the scope of the Mendelian law. The manner in which a germ-cell can force upon the adult certain characters will not be understood until we succeed in varying and controlling hereditary characteristics; and this can only be accomplished on the basis of a systematic study of the effects of chemical and physical forces upon living matter. Owing to limitation of space this sketch is necessarily very incomplete, and it must not be inferred that studies which are not mentioned here were considered to be of minor importance. All the writer could hope to do was to bring together a few instances of the experimental analysis of the effect of environment, which indicate the nature and extent of our control over life-phenomena and which also have some relation to the work of Darwin. In the selection of these instances preference is given to those problems which are not too technical for the general reader. The forces, the influence of which we shall discuss, are in succession chemical agencies, temperature, light, and gravitation. We shall also treat separately the effect of these forces upon form and instinctive reactions. II. THE EFFECTS OF CHEMICAL AGENCIES. (a) HETEROGENEOUS HYBRIDISATION. It was held until recently that hybridisation is not possible except between closely related species and that even among these a successful hybridisation cannot always be counted upon. This view was well supported by experience. It is, for instance, well known that the majority of marine animals lay their unfertilised eggs in the ocean and that the males shed their sperm also into the sea-water. The numerical excess of the spermatozoa over the ova in the sea-water is the only guarantee that the eggs are fertilised, for the spermatozoa are carried to the eggs by chance and are not attracted by the latter. This statement is the result of numerous experiments by various authors, and is contrary to common belief. As a rule all or the majority of individuals of a species in a given region spawn on the same day, and when this occurs the sea-water constitutes a veritable suspension of sperm. It has been shown by experiment that in fresh sea-water the sperm may live and retain its fertilising power for several days. It is thus unavoidable that at certain periods more than one kind of spermatozoon is suspended in the sea-water and it is a matter of surprise that the most heterogeneous hybridisations do not constantly occur. The reason for this becomes obvious if we bring together mature eggs and equally mature and active sperm of a different family. When this is done no egg is, as a rule, fertilised. The eggs of a sea-urchin can be fertilised by sperm of their own species, or, though in smaller numbers, by the sperm of other species of sea-urchins, but not by the sperm of other groups of echinoderms, e.g. starfish, brittle-stars, holothurians or crinoids, and still less by the sperm of more distant groups of animals. The consensus of opinion seemed to be that the spermatozoon must enter the egg through a narrow opening or canal, the so-called micropyle, and that the micropyle allowed only the spermatozoa of the same or of a closely related species to enter the egg. It seemed to the writer that the cause of this limitation of hybridisation might be of another kind and that by a change in the constitution of the sea-water it might be possible to bring about heterogenous hybridisations, which in normal sea-water are impossible. This assumption proved correct. Sea-water has a faintly alkaline reaction (in terms of the physical chemist its concentration of hydroxyl ions is about (10 to the power minus six)N at Pacific Grove, California, and about (10 to the power minus 5)N at Woods Hole, Massachusetts). If we slightly raise the alkalinity of the sea-water by adding to it a small but definite quantity of sodium hydroxide or some other alkali, the eggs of the sea-urchin can be fertilised with the sperm of widely different groups of animals, possibly with the sperm of any marine animal which sheds it into the ocean. In 1903 it was shown that if we add from about 0.5 to 0.8 cubic centimetre N/10 sodium hydroxide to 50 cubic centimetres of sea-water, the eggs of Strongylocentrotus purpuratus (a sea-urchin which is found on the coast of California) can be fertilised in large quantities by the sperm of various kinds of starfish, brittle-stars and holothurians; while in normal sea-water or with less sodium hydroxide not a single egg of the same female could be fertilised with the starfish sperm which proved effective in the hyper-alkaline sea-water. The sperm of the various forms of starfish was not equally effective for these hybridisations; the sperm of Asterias ochracea and A. capitata gave the best results, since it was possible to fertilise 50 per cent or more of the sea-urchin eggs, while the sperm of Pycnopodia and Asterina fertilised only 2 per cent of the same eggs. Godlewski used the same method for the hybridisation of the sea-urchin eggs with the sperm of a crinoid (Antedon rosacea). Kupelwieser afterwards obtained results which seemed to indicate the possibility of fertilising the eggs of Strongylocentrotus with the sperm of a mollusc (Mytilus.) Recently, the writer succeeded in fertilising the eggs of Strongylocentrotus franciscanus with the sperm of a mollusc--Chlorostoma. This result could only be obtained in sea-water the alkalinity of which had been increased (through the addition of 0.8 cubic centimetre N/10 sodium hydroxide to 50 cubic centimetres of sea-water). We thus see that by increasing the alkalinity of the sea-water it is possible to effect heterogeneous hybridisations which are at present impossible in the natural environment of these animals. It is, however, conceivable that in former periods of the earth's history such heterogeneous hybridisations were possible. It is known that in solutions like sea-water the degree of alkalinity must increase when the amount of carbon-dioxide in the atmosphere is diminished. If it be true, as Arrhenius assumes, that the Ice age was caused or preceded by a diminution in the amount of carbon-dioxide in the air, such a diminution must also have resulted in an increase of the alkalinity of the sea-water, and one result of such an increase must have been to render possible heterogeneous hybridisations in the ocean which in the present state of alkalinity are practically excluded. But granted that such hybridisations were possible, would they have influenced the character of the fauna? In other words, are the hybrids between sea-urchin and starfish, or better still, between sea-urchin and mollusc, capable of development, and if so, what is their character? The first experiment made it appear doubtful whether these heterogeneous hybrids could live. The sea-urchin eggs which were fertilised in the laboratory by the spermatozoa of the starfish, as a rule, died earlier than those of the pure breeds. But more recent results indicate that this was due merely to deficiencies in the technique of the earlier experiments. The writer has recently obtained hybrid larvae between the sea-urchin egg and the sperm of a mollusc (Chlorostoma) which, in the laboratory, developed as well and lived as long as the pure breeds of the sea-urchin, and there was nothing to indicate any difference in the vitality of the two breeds. So far as the question of heredity is concerned, all the experiments on heterogeneous hybridisation of the egg of the sea-urchin with the sperm of starfish, brittle-stars, crinoids and molluscs, have led to the same result, namely, that the larvae have purely maternal characteristics and differ in no way from the pure breed of the form from which the egg is taken. By way of illustration it may be said that the larvae of the sea-urchin reach on the third day or earlier (according to species and temperature) the so-called pluteus stage, in which they possess a typical skeleton; while neither the larvae of the starfish nor those of the mollusc form a skeleton at the corresponding stage. It was, therefore, a matter of some interest to find out whether or not the larvae produced by the fertilisation of the sea-urchin egg with the sperm of starfish or mollusc would form the normal and typical pluteus skeleton. This was invariably the case in the experiments of Godlewski, Kupelwieser, Hagedoorn, and the writer. These hybrid larvae were exclusively maternal in character. It might be argued that in the case of heterogeneous hybridisation the sperm-nucleus does not fuse with the egg-nucleus, and that, therefore, the spermatozoon cannot transmit its hereditary substances to the larvae. But these objections are refuted by Godlewski's experiments, in which he showed definitely that if the egg of the sea-urchin is fertilised with the sperm of a crinoid the fusion of the egg-nucleus and sperm-nucleus takes place in the normal way. It remains for further experiments to decide what the character of the adult hybrids would be. (b). ARTIFICIAL PARTHENOGENESIS. Possibly in no other field of Biology has our ability to control life-phenomena by outside conditions been proved to such an extent as in the domain of fertilisation. The reader knows that the eggs of the overwhelming majority of animals cannot develop unless a spermatozoon enters them. In this case a living agency is the cause of development and the problem arises whether it is possible to accomplish the same result through the application of well-known physico-chemical agencies. This is, indeed, true, and during the last ten years living larvae have been produced by chemical agencies from the unfertilised eggs of sea-urchins, starfish, holothurians and a number of annelids and molluscs; in fact this holds true in regard to the eggs of practically all forms of animals with which such experiments have been tried long enough. In each form the method of procedure is somewhat different and a long series of experiments is often required before the successful method is found. The facts of Artificial Parthenogenesis, as the chemical fertilisation of the egg is called, have, perhaps, some bearing on the problem of evolution. If we wish to form a mental image of the process of evolution we have to reckon with the possibility that parthenogenetic propagation may have preceded sexual reproduction. This suggests also the possibility that at that period outside forces may have supplied the conditions for the development of the egg which at present the spermatozoon has to supply. For this, if for no other reason, a brief consideration of the means of artificial parthenogenesis may be of interest to the student of evolution. It seemed necessary in these experiments to imitate as completely as possible by chemical agencies the effects of the spermatozoon upon the egg. When a spermatozoon enters the egg of a sea-urchin or certain starfish or annelids, the immediate effect is a characteristic change of the surface of the egg, namely the formation of the so-called membrane of fertilisation. The writer found that we can produce this membrane in the unfertilised egg by certain acids, especially the monobasic acids of the fatty series, e.g. formic, acetic, propionic, butyric, etc. Carbon-dioxide is also very efficient in this direction. It was also found that the higher acids are more efficient than the lower ones, and it is possible that the spermatozoon induces membrane-formation by carrying into the egg a higher fatty acid, namely oleic acid or one of its salts or esters. The physico-chemical process which underlies the formation of the membrane seems to be the cause of the development of the egg. In all cases in which the unfertilised egg has been treated in such a way as to cause it to form a membrane it begins to develop. For the eggs of certain animals membrane-formation is all that is required to induce a complete development of the unfertilised egg, e.g. in the starfish and certain annelids. For the eggs of other animals a second treatment is necessary, presumably to overcome some of the injurious effects of acid treatment. Thus the unfertilised eggs of the sea-urchin Strongylocentrotus purpuratus of the Californian coast begin to develop when membrane-formation has been induced by treatment with a fatty acid, e.g. butyric acid; but the development soon ceases and the eggs perish in the early stages of segmentation, or after the first nuclear division. But if we treat the same eggs, after membrane-formation, for from 35 to 55 minutes (at 15 deg C.) with sea-water the concentration (osmotic pressure) of which has been raised through the addition of a definite amount of some salt or sugar, the eggs will segment and develop normally, when transferred back to normal sea-water. If care is taken, practically all the eggs can be caused to develop into plutei, the majority of which may be perfectly normal and may live as long as larvae produced from eggs fertilised with sperm. It is obvious that the sea-urchin egg is injured in the process of membrane-formation and that the subsequent treatment with a hypertonic solution only acts as a remedy. The nature of this injury became clear when it was discovered that all the agencies which cause haemolysis, i.e. the destruction of the red blood corpuscles, also cause membrane-formation in unfertilised eggs, e.g. fatty acids or ether, alcohols or chloroform, etc., or saponin, solanin, digitalin, bile salts and alkali. It thus happens that the phenomena of artificial parthenogenesis are linked together with the phenomena of haemolysis which at present play so important a role in the study of immunity. The difference between cytolysis (or haemolysis) and fertilisation seems to be this, that the latter is caused by a superficial or slight cytolysis of the egg, while if the cytolytic agencies have time to act on the whole egg the latter is completely destroyed. If we put unfertilised eggs of a sea-urchin into sea-water which contains a trace of saponin we notice that, after a few minutes, all the eggs form the typical membrane of fertilisation. If the eggs are then taken out of the saponin solution, freed from all traces of saponin by repeated washing in normal sea-water, and transferred to the hypertonic sea-water for from 35 to 55 minutes, they develop into larvae. If, however, they are left in the sea-water containing the saponin they undergo, a few minutes after membrane-formation, the disintegration known in pathology as CYTOLYSIS. Membrane-formation is, therefore, caused by a superficial or incomplete cytolysis. The writer believes that the subsequent treatment of the egg with hypertonic sea-water is needed only to overcome the destructive effects of this partial cytolysis. The full reasons for this belief cannot be given in a short essay. Many pathologists assume that haemolysis or cytolysis is due to a liquefaction of certain fatty or fat-like compounds, the so-called lipoids, in the cell. If this view is correct, it would be necessary to ascribe the fertilisation of the egg to the same process. The analogy between haemolysis and fertilisation throws, possibly, some light on a curious observation. It is well known that the blood corpuscles, as a rule, undergo cytolysis if injected into the blood of an animal which belongs to a different family. The writer found last year that the blood of mammals, e.g. the rabbit, pig, and cattle, causes the egg of Strongylocentrotus to form a typical fertilisation-membrane. If such eggs are afterwards treated for a short period with hypertonic sea-water they develop into normal larvae (plutei). Some substance contained in the blood causes, presumably, a superficial cytolysis of the egg and thus starts its development. We can also cause the development of the sea-urchin egg without membrane-formation. The early experiments of the writer were done in this way and many experimenters still use such methods. It is probable that in this case the mechanism of fertilisation is essentially the same as in the case where the membrane-formation is brought about, with this difference only, that the cytolytic effect is less when no fertilisation-membrane is formed. This inference is corroborated by observations on the fertilisation of the sea-urchin egg with ox blood. It very frequently happens that not all of the eggs form membranes in this process. Those eggs which form membranes begin to develop, but perish if they are not treated with hypertonic sea-water. Some of the other eggs, however, which do not form membranes, develop directly into normal larvae without any treatment with hypertonic sea-water, provided they are exposed to the blood for only a few minutes. Presumably some blood enters the eggs and causes the cytolytic effects in a less degree than is necessary for membrane-formation, but in a sufficient degree to cause their development. The slightness of the cytolytic effect allows the egg to develop without treatment with hypertonic sea-water. Since the entrance of the spermatozoon causes that degree of cytolysis which leads to membrane-formation, it is probable that, in addition to the cytolytic or membrane-forming substance (presumably a higher fatty acid), it carries another substance into the egg which counteracts the deleterious cytolytic effects underlying membrane-formation. The question may be raised whether the larvae produced by artificial parthenogenesis can reach the mature stage. This question may be answered in the affirmative, since Delage has succeeded in raising several parthenogenetic sea-urchin larvae beyond the metamorphosis into the adult stage and since in all the experiments made by the writer the parthenogenetic plutei lived as long as the plutei produced from fertilised eggs. (c). ON THE PRODUCTION OF TWINS FROM ONE EGG THROUGH A CHANGE IN THE CHEMICAL CONSTITUTION OF THE SEA-WATER. The reader is probably familiar with the fact that there exist two different types of human twins. In the one type the twins differ as much as two children of the same parents born at different periods; they may or may not have the same sex. In the second type the twins have invariably the same sex and resemble each other most closely. Twins of the latter type are produced from the same egg, while twins of the former type are produced from two different eggs. The experiments of Driesch and others have taught us that twins originate from one egg in this manner, namely, that the first two cells into which the egg divides after fertilisation become separated from each other. This separation can be brought about by a change in the chemical constitution of the sea-water. Herbst observed that if the fertilised eggs of the sea-urchin are put into sea-water which is freed from calcium, the cells into which the egg divides have a tendency to fall apart. Driesch afterwards noticed that eggs of the sea-urchin treated with sea-water which is free from lime have a tendency to give rise to twins. The writer has recently found that twins can be produced not only by the absence of lime, but also through the absence of sodium or of potassium; in other words, through the absence of one or two of the three important metals in the sea-water. There is, however, a second condition, namely, that the solution used for the production of twins must have a neutral or at least not an alkaline reaction. The procedure for the production of twins in the sea-urchin egg consists simply in this:--the eggs are fertilised as usual in normal sea-water and then, after repeated washing in a neutral solution of sodium chloride (of the concentration of the sea-water), are placed in a neutral mixture of potassium chloride and calcium chloride, or of sodium chloride and potassium chloride, or of sodium chloride and calcium chloride, or of sodium chloride and magnesium chloride. The eggs must remain in this solution until half an hour or an hour after they have reached the two-cell stage. They are then transferred into normal sea-water and allowed to develop. From 50 to 90 per cent of the eggs of Strongylocentrotus purpuratus treated in this manner may develop into twins. These twins may remain separate or grow partially together and form double monsters, or heal together so completely that only slight or even no imperfections indicate that the individual started its career as a pair of twins. It is also possible to control the tendency of such twins to grow together by a change in the constitution of the sea-water. If we use as a twin-producing solution a mixture of sodium, magnesium and potassium chlorides (in the proportion in which these salts exist in the sea-water) the tendency of the twins to grow together is much more pronounced than if we use simply a mixture of sodium chloride and magnesium chloride. The mechanism of the origin of twins, as the result of altering the composition of the sea-water, is revealed by observation of the first segmentation of the egg in these solutions. This cell-division is modified in a way which leads to a separation of the first two cells. If the egg is afterwards transferred back into normal sea-water, each of these two cells develops into an independent embryo. Since normal sea-water contains all three metals, sodium, calcium, and potassium, and since it has besides an alkaline reaction, we perceive the reason why twins are not normally produced from one egg. These experiments suggest the possibility of a chemical cause for the origin of twins from one egg or of double monstrosities in mammals. If, for some reason, the liquids which surround the human egg a short time before and after the first cell-division are slightly acid, and at the same time lacking in one of the three important metals, the conditions for the separation of the first two cells and the formation of identical twins are provided. In conclusion it may be pointed out that the reverse result, namely, the fusion of normally double organs, can also be brought about experimentally through a change in the chemical constitution of the sea-water. Stockard succeeded in causing the eyes of fish embryos (Fundulus heteroclitus) to fuse into a single cyclopean eye through the addition of magnesium chloride to the sea-water. When he added about 6 grams of magnesium chloride to 100 cubic centimetres of sea-water and placed the fertilised eggs in the mixture, about 50 per cent of the eggs gave rise to one-eyed embryos. "When the embryos were studied the one-eyed condition was found to result from the union or fusion of the 'anlagen' of the two eyes. Cases were observed which showed various degrees in this fusion; it appeared as though the optic vessels were formed too far forward and ventral, so that their antero-ventro-median surfaces fused. This produces one large optic cup, which in all cases gives more or less evidence of its double nature." (Stockard, "Archiv f. Entwickelungsmechanik", Vol. 23, page 249, 1907.) We have confined ourselves to a discussion of rather simple effects of the change in the constitution of the sea-water upon development. It is a priori obvious, however, that an unlimited number of pathological variations might be produced by a variation in the concentration and constitution of the sea-water, and experience confirms this statement. As an example we may mention the abnormalities observed by Herbst in the development of sea-urchins through the addition of lithium to sea-water. It is, however, as yet impossible to connect in a rational way the effects produced in this and similar cases with the cause which produced them; and it is also impossible to define in a simple way the character of the change produced. III. THE INFLUENCE OF TEMPERATURE. (a) THE INFLUENCE OF TEMPERATURE UPON THE DENSITY OF PELAGIC ORGANISMS AND THE DURATION OF LIFE. It has often been noticed by explorers who have had a chance to compare the faunas in different climates that in polar seas such species as thrive at all in those regions occur, as a rule, in much greater density than they do in the moderate or warmer regions of the ocean. This refers to those members of the fauna which live at or near the surface, since they alone lend themselves to a statistical comparison. In his account of the Valdivia expedition, Chun (Chun, "Aus den Tiefen des Weltmeeres", page 225, Jena, 1903.) calls especial attention to this quantitative difference in the surface fauna and flora of different regions. "In the icy water of the Antarctic, the temperature of which is below 0 deg C., we find an astonishingly rich animal and plant life. The same condition with which we are familiar in the Arctic seas is repeated here, namely, that the quantity of plankton material exceeds that of the temperate and warm seas." And again, in regard to the pelagic fauna in the region of the Kerguelen Islands, he states: "The ocean is alive with transparent jelly fish, Ctenophores (Bolina and Callianira) and of Siphonophore colonies of the genus Agalma." The paradoxical character of this general observation lies in the fact that a low temperature retards development, and hence should be expected to have the opposite effect from that mentioned by Chun. Recent investigations have led to the result that life-phenomena are affected by temperature in the same sense as the velocity of chemical reactions. In the case of the latter van't Hoff had shown that a decrease in temperature by 10 degrees reduces their velocity to one half or less, and the same has been found for the influence of temperature on the velocity of physiological processes. Thus Snyder and T.B. Robertson found that the rate of heartbeat in the tortoise and in Daphnia is reduced to about one-half if the temperature is lowered 10 deg C., and Maxwell, Keith Lucas, and Snyder found the same influence of temperature for the rate with which an impulse travels in the nerve. Peter observed that the rate of development in a sea-urchin's egg is reduced to less than one-half if the temperature (within certain limits) is reduced by 10 degrees. The same effect of temperature upon the rate of development holds for the egg of the frog, as Cohen and Peter calculated from the experiments of O. Hertwig. The writer found the same temperature-coefficient for the rate of maturation of the egg of a mollusc (Lottia). All these facts prove that the velocity of development of animal life in Arctic regions, where the temperature is near the freezing point of water, must be from two to three times smaller than in regions where the temperature of the ocean is about 10 deg C. and from four to nine times smaller than in seas the temperature of which is about 20 deg C. It is, therefore, exactly the reverse of what we should expect when authors state that the density of organisms at or near the surface of the ocean in polar regions is greater than in more temperate regions. The writer believes that this paradox finds its explanation in experiments which he has recently made on the influence of temperature on the duration of life of cold-blooded marine animals. The experiments were made on the fertilised and unfertilised eggs of the sea-urchin, and yielded the result that for the lowering of temperature by 1 deg C. the duration of life was about doubled. Lowering the temperature by 10 degrees therefore prolongs the life of the organism 2 to the power 10, i.e. over a thousand times, and a lowering by 20 degrees prolongs it about one million times. Since this prolongation of life is far in excess of the retardation of development through a lowering of temperature, it is obvious that, in spite of the retardation of development in Arctic seas, animal life must be denser there than in temperate or tropical seas. The excessive increase of the duration of life at the poles will necessitate the simultaneous existence of more successive generations of the same species in these regions than in the temperate or tropical regions. The writer is inclined to believe that these results have some bearing upon a problem which plays an important role in theories of evolution, namely, the cause of natural death. It has been stated that the processes of differentiation and development lead also to the natural death of the individual. If we express this in chemical terms it means that the chemical processes which underlie development also determine natural death. Physical chemistry has taught us to identify two chemical processes even if only certain of their features are known. One of these means of identification is the temperature coefficient. When two chemical processes are identical, their velocity must be reduced by the same amount if the temperature is lowered to the same extent. The temperature coefficient for the duration of life of cold-blooded organisms seems, however, to differ enormously from the temperature coefficient for their rate of development. For a difference in temperature of 10 deg C. the duration of life is altered five hundred times as much as the rate of development; and, for a change of 20 deg C., it is altered more than a hundred thousand times as much. From this we may conclude that, at least for the sea-urchin eggs and embryo, the chemical processes which determine natural death are certainly not identical with the processes which underlie their development. T.B. Robertson has also arrived at the conclusion, for quite different reasons, that the process of senile decay is essentially different from that of growth and development. (b) CHANGES IN THE COLOUR OF BUTTERFLIES PRODUCED THROUGH THE INFLUENCE OF TEMPERATURE. The experiments of Dorfmeister, Weismann, Merrifield, Standfuss, and Fischer, on seasonal dimorphism and the aberration of colour in butterflies have so often been discussed in biological literature that a short reference to them will suffice. By seasonal dimorphism is meant the fact that species may appear at different seasons of the year in a somewhat different form or colour. Vanessa prorsa is the summer form, Vanessa levana the winter form of the same species. By keeping the pupae of Vanessa prorsa several weeks at a temperature of from 0 deg to 1 deg Weismann succeeded in obtaining from the summer chrysalids specimens which resembled the winter variety, Vanessa levana. If we wish to get a clear understanding of the causes of variation in the colour and pattern of butterflies, we must direct our attention to the experiments of Fischer, who worked with more extreme temperatures than his predecessors, and found that almost identical aberrations of colour could be produced by both extremely high and extremely low temperatures. This can be clearly seen from the following tabulated results of his observations. At the head of each column the reader finds the temperature to which Fischer submitted the pupae, and in the vertical column below are found the varieties that were produced. In the vertical column A are given the normal forms: (Temperatures in deg C.) 0 to -20 0 to +10 A. +35 to +37 +36 to +41 +42 to +46 (Normal forms) ichnusoides polaris urticae ichnusa polaris ichnusoides (nigrita) (nigrita) antigone fischeri io - fischeri antigone (iokaste) (iokaste) testudo dixeyi polychloros erythromelas dixeyi testudo hygiaea artemis antiopa epione artemis hygiaea elymi wiskotti cardui - wiskotti elymi klymene merrifieldi atalanta - merrifieldi klymene weismanni porima prorsa - porima weismanni The reader will notice that the aberrations produced at a very low temperature (from 0 to -20 deg C.) are absolutely identical with the aberrations produced by exposing the pupae to extremely high temperatures (42 to 46 deg C.). Moreover the aberrations produced by a moderately low temperature (from 0 to 10 deg C.) are identical with the aberrations produced by a moderately high temperature (36 to 41 deg C.) From these observations Fischer concludes that it is erroneous to speak of a specific effect of high and of low temperatures, but that there must be a common cause for the aberration found at the high as well as at the low temperature limits. This cause he seems to find in the inhibiting effects of extreme temperatures upon development. If we try to analyse such results as Fischer's from a physico-chemical point of view, we must realise that what we call life consists of a series of chemical reactions, which are connected in a catenary way; inasmuch as one reaction or group of reactions (a) (e.g. hydrolyses) causes or furnishes the material for a second reaction or group of reactions (b) (e.g. oxydations). We know that the temperature coefficient for physiological processes varies slightly at various parts of the scale; as a rule it is higher near 0 and lower near 30 deg. But we know also that the temperature coefficients do not vary equally from the various physiological processes. It is, therefore, to be expected that the temperature coefficients for the group of reactions of the type (a) will not be identical through the whole scale with the temperature coefficients for the reactions of the type (b). If therefore a certain substance is formed at the normal temperature of the animal in such quantities as are needed for the catenary reaction (b), it is not to be expected that this same perfect balance will be maintained for extremely high or extremely low temperatures; it is more probable that one group of reactions will exceed the other and thus produce aberrant chemical effects, which may underlie the colour aberrations observed by Fischer and other experimenters. It is important to notice that Fischer was also able to produce aberrations through the application of narcotics. Wolfgang Ostwald has produced experimentally, through variation of temperature, dimorphism of form in Daphnia. Lack of space precludes an account of these important experiments, as of so many others. IV. THE EFFECTS OF LIGHT. At the present day nobody seriously questions the statement that the action of light upon organisms is primarily one of a chemical character. While this chemical action is of the utmost importance for organisms, the nutrition of which depends upon the action of chlorophyll, it becomes of less importance for organisms devoid of chlorophyll. Nevertheless, we find animals in which the formation of organs by regeneration is not possible unless they are exposed to light. An observation made by the writer on the regeneration of polyps in a hydroid, Eudendrium racemosum, at Woods Hole, may be mentioned as an instance of this. If the stem of this hydroid, which is usually covered with polyps, is put into an aquarium the polyps soon fall off. If the stems are kept in an aquarium where light strikes them during the day, a regeneration of numerous polyps takes place in a few days. If, however, the stems of Eudendrium are kept permanently in the dark, no polyps are formed even after an interval of some weeks; but they are formed in a few days after the same stems have been transferred from the dark to the light. Diffused daylight suffices for this effect. Goldfarb, who repeated these experiments, states that an exposure of comparatively short duration is sufficient for this effect, it is possible that the light favours the formation of substances which are a prerequisite for the origin of polyps and their growth. Of much greater significance than this observation are the facts which show that a large number of animals assume, to some extent, the colour of the ground on which they are placed. Pouchet found through experiments upon crustaceans and fish that this influence of the ground on the colour of animals is produced through the medium of the eyes. If the eyes are removed or the animals made blind in another way these phenomena cease. The second general fact found by Pouchet was that the variation in the colour of the animal is brought about through an action of the nerves on the pigment-cells of the skin; the nerve-action being induced through the agency of the eye. The mechanism and the conditions for the change in colouration were made clear through the beautiful investigations of Keeble and Gamble, on the colour-change in crustaceans. According to these authors the pigment-cells can, as a rule, be considered as consisting of a central body from which a system of more or less complicated ramifications or processes spreads out in all directions. As a rule, the centre of the cell contains one or more different pigments which under the influence of nerves can spread out separately or together into the ramifications. These phenomena of spreading and retraction of the pigments into or from the ramifications of the pigment-cells form on the whole the basis for the colour changes under the influence of environment. Thus Keeble and Gamble observed that Macromysis flexuosa appears transparent and colourless or grey on sandy ground. On a dark ground their colour becomes darker. These animals have two pigments in their chromatophores, a brown pigment and a whitish or yellow pigment; the former is much more plentiful than the latter. When the animal appears transparent all the pigment is contained in the centre of the cells, while the ramifications are free from pigment. When the animal appears brown both pigments are spread out into the ramifications. In the condition of maximal spreading the animals appear black. This is a comparatively simple case. Much more complicated conditions were found by Keeble and Gamble in other crustaceans, e.g. in Hippolyte cranchii, but the influence of the surroundings upon the colouration of this form was also satisfactorily analysed by these authors. While many animals show transitory changes in colour under the influence of their surroundings, in a few cases permanent changes can be produced. The best examples of this are those which were observed by Poulton in the chrysalids of various butterflies, especially the small tortoise-shell. These experiments are so well known that a short reference to them will suffice. Poulton (Poulton, E.B., "Colours of Animals" (The International Scientific Series), London, 1890, page 121.) found that in gilt or white surroundings the pupae became light coloured and there was often an immense development of the golden spots, "so that in many cases the whole surface of the pupae glittered with an apparent metallic lustre. So remarkable was the appearance that a physicist to whom I showed the chrysalids, suggested that I had played a trick and had covered them with goldleaf." When black surroundings were used "the pupae were as a rule extremely dark, with only the smallest trace, and often no trace at all, of the golden spots which are so conspicuous in the lighter form." The susceptibility of the animal to this influence of its surroundings was found to be greatest during a definite period when the caterpillar undergoes the metamorphosis into the chrysalis stage. As far as the writer is aware, no physico-chemical explanation, except possibly Wiener's suggestion of colour-photography by mechanical colour adaptation, has ever been offered for the results of the type of those observed by Poulton. V. EFFECTS OF GRAVITATION. (a) EXPERIMENTS ON THE EGG OF THE FROG. Gravitation can only indirectly affect life-phenomena; namely, when we have in a cell two different non-miscible liquids (or a liquid and a solid) of different specific gravity, so that a change in the position of the cell or the organ may give results which can be traced to a change in the position of the two substances. This is very nicely illustrated by the frog's egg, which has two layers of very viscous protoplasm one of which is black and one white. The dark one occupies normally the upper position in the egg and may therefore be assumed to possess a smaller specific gravity than the white substance. When the egg is turned with the white pole upwards a tendency of the white protoplasm to flow down again manifests itself. It is, however, possible to prevent or retard this rotation of the highly viscous protoplasm, by compressing the eggs between horizontal glass plates. Such compression experiments may lead to rather interesting results, as O. Schultze first pointed out. Pflueger had already shown that the first plane of division in a fertilised frog's egg is vertical and Roux established the fact that the first plane of division is identical with the plane of symmetry of the later embryo. Schultze found that if the frog's egg is turned upside down at the time of its first division and kept in this abnormal position, through compression between two glass plates for about 20 hours, a small number of eggs may give rise to twins. It is possible, in this case, that the tendency of the black part of the egg to rotate upwards along the surface of the egg leads to a separation of its first cells, such a separation leading to the formation of twins. T.H. Morgan made an interesting additional observation. He destroyed one half of the egg after the first segmentation and found that the half which remained alive gave rise to only one half of an embryo, thus confirming an older observation of Roux. When, however, Morgan put the egg upside down after the destruction of one of the first two cells, and compressed the eggs between two glass plates, the surviving half of the egg gave rise to a perfect embryo of half size (and not to a half embryo of normal size as before.) Obviously in this case the tendency of the protoplasm to flow back to its normal position was partially successful and led to a partial or complete separation of the living from the dead half; whereby the former was enabled to form a whole embryo, which, of course, possessed only half the size of an embryo originating from a whole egg. (b) EXPERIMENTS ON HYDROIDS. A striking influence of gravitation can be observed in a hydroid, Antennularia antennina, from the bay of Naples. This hydroid consists of a long straight main stem which grows vertically upwards and which has at regular intervals very fine and short bristle-like lateral branches, on the upper side of which the polyps grow. The main stem is negatively geotropic, i.e. its apex continues to grow vertically upwards when we put it obliquely into the aquarium, while the roots grow vertically downwards. The writer observed that when the stem is put horizontally into the water the short lateral branches on the lower side give rise to an altogether different kind of organ, namely, to roots, and these roots grow indefinitely in length and attach themselves to solid bodies; while if the stem had remained in its normal position no further growth would have occurred in the lateral branches. From the upper side of the horizontal stem new stems grow out, mostly directly from the original stem, occasionally also from the short lateral branches. It is thus possible to force upon this hydroid an arrangement of organs which is altogether different from the hereditary arrangement. The writer had called the change in the hereditary arrangement of organs or the transformation of organs by external forces HETEROMORPHOSIS. We cannot now go any further into this subject, which should, however, prove of interest in relation to the problem of heredity. If it is correct to apply inferences drawn from the observation on the frog's egg to the behaviour of Antennularia, one might conclude that the cells of Antennularia also contain non-miscible substances of different specific gravity, and that wherever the specifically lighter substance comes in contact with the sea-water (or gets near the surface of the cell) the growth of a stem is favoured; while contact with the sea-water of the specifically heavier of the substances, will favour the formation of roots. VI. THE EXPERIMENTAL CONTROL OF ANIMAL INSTINCTS. (a) EXPERIMENTS ON THE MECHANISM OF HELIOTROPIC REACTIONS IN ANIMALS. Since the instinctive reactions of animals are as hereditary as their morphological character, a discussion of experiments on the physico-chemical character of the instinctive reactions of animals should not be entirely omitted from this sketch. It is obvious that such experiments must begin with the simplest type of instincts, if they are expected to lead to any results; and it is also obvious that only such animals must be selected for this purpose, the reactions of which are not complicated by associative memory, or, as it may preferably be termed, associative hysteresis. The simplest type of instincts is represented by the purposeful motions of animals to or from a source of energy, e.g. light; and it is with some of these that we intend to deal here. When we expose winged aphides (after they have flown away from the plant), or young caterpillars of Porthesia chrysorrhoea (when they are aroused from their winter sleep) or marine or freshwater copepods and many other animals, to diffused daylight falling in from a window, we notice a tendency among these animals to move towards the source of light. If the animals are naturally sensitive, or if they are rendered sensitive through the agencies which we shall mention later, and if the light is strong enough, they move towards the source of light in as straight a line as the imperfections and peculiarities of their locomotor apparatus will permit. It is also obvious that we are here dealing with a forced reaction in which the animals have no more choice in the direction of their motion than have the iron filings in their arrangement in a magnetic field. This can be proved very nicely in the case of starving caterpillars of Porthesia. The writer put such caterpillars into a glass tube the axis of which was at right angles to the plane of the window: the caterpillars went to the window side of the tube and remained there, even if leaves of their food-plant were put into the tube directly behind them. Under such conditions the animals actually died from starvation, the light preventing them from turning to the food, which they eagerly ate when the light allowed them to do so. One cannot say that these animals, which we call positively helioptropic, are attracted by the light, since it can be shown that they go towards the source of the light even if in so doing they move from places of a higher to places of a lower degree of illumination. The writer has advanced the following theory of these instinctive reactions. Animals of the type of those mentioned are automatically orientated by the light in such a way that symmetrical elements of their retina (or skin) are struck by the rays of light at the same angle. In this case the intensity of light is the same for both retinae or symmetrical parts of the skin. This automatic orientation is determined by two factors, first a peculiar photo-sensitiveness of the retina (or skin), and second a peculiar nervous connection between the retina and the muscular apparatus. In symmetrically built heliotropic animals in which the symmetrical muscles participate equally in locomotion, the symmetrical muscles work with equal energy as long as the photo-chemical processes in both eyes are identical. If, however, one eye is struck by stronger light than the other, the symmetrical muscles will work unequally and in positively heliotropic animals those muscles will work with greater energy which bring the plane of symmetry back into the direction of the rays of light and the head towards the source of light. As soon as both eyes are struck by the rays of light at the same angle, there is no more reason for the animal to deviate from this direction and it will move in a straight line. All this holds good on the supposition that the animals are exposed to only one source of light and are very sensitive to light. Additional proof for the correctness of this theory was furnished through the experiments of G.H. Parker and S.J. Holmes. The former worked on a butterfly, Vanessa antiope, the latter on other arthropods. All the animals were in a marked degree positively heliotropic. These authors found that if one cornea is blackened in such an animal, it moves continually in a circle when it is exposed to a source of light, and in these motions the eye which is not covered with paint is directed towards the centre of the circle. The animal behaves, therefore, as if the darkened eye were in the shade. (b) THE PRODUCTION OF POSITIVE HELIOTROPISM BY ACIDS AND OTHER MEANS AND THE PERIODIC DEPTH-MIGRATIONS OF PELAGIC ANIMALS. When we observe a dense mass of copepods collected from a freshwater pond, we notice that some have a tendency to go to the light while others go in the opposite direction and many, if not the majority, are indifferent to light. It is an easy matter to make the negatively heliotropic or the indifferent copepods almost instantly positively heliotropic by adding a small but definite amount of carbon-dioxide in the form of carbonated water to the water in which the animals are contained. If the animals are contained in 50 cubic centimetres of water it suffices to add from three to six cubic centimetres of carbonated water to make all the copepods energetically positively heliotropic. This heliotropism lasts about half an hour (probably until all the carbon-dioxide has again diffused into the air.) Similar results may be obtained with any other acid. The same experiments may be made with another freshwater crustacean, namely Daphnia, with this difference, however, that it is as a rule necessary to lower the temperature of the water also. If the water containing the Daphniae is cooled and at the same time carbon-dioxide added, the animals which were before indifferent to light now become most strikingly positively heliotropic. Marine copepods can be made positively heliotropic by the lowering of the temperature alone, or by a sudden increase in the concentration of the sea-water. These data have a bearing upon the depth-migrations of pelagic animals, as was pointed out years ago by Theo. T. Groom and the writer. It is well known that many animals living near the surface of the ocean or freshwater lakes, have a tendency to migrate upwards towards evening and downwards in the morning and during the day. These periodic motions are determined to a large extent, if not exclusively, by the heliotropism of these animals. Since the consumption of carbon-dioxide by the green plants ceases towards evening, the tension of this gas in the water must rise and this must have the effect of inducing positive heliotropism or increasing its intensity. At the same time the temperature of the water near the surface is lowered and this also increases the positive heliotropism in the organisms. The faint light from the sky is sufficient to cause animals which are in a high degree positively heliotropic to move vertically upwards towards the light, as experiments with such pelagic animals, e.g. copepods, have shown. When, in the morning, the absorption of carbon-dioxide by the green algae begins again and the temperature of the water rises, the animals lose their positive heliotropism, and slowly sink down or become negatively heliotropic and migrate actively downwards. These experiments have also a bearing upon the problem of the inheritance of instincts. The character which is transmitted in this case is not the tendency to migrate periodically upwards and downwards, but the positive heliotropism. The tendency to migrate is the outcome of the fact that periodically varying external conditions induce a periodic change in the sense and intensity of the heliotropism of these animals. It is of course immaterial for the result, whether the carbon-dioxide or any other acid diffuse into the animal from the outside or whether they are produced inside in the tissue cells of the animals. Davenport and Cannon found that Daphniae, which at the beginning of the experiment, react sluggishly to light react much more quickly after they have been made to go to the light a few times. The writer is inclined to attribute this result to the effect of acids, e.g. carbon-dioxide, produced in the animals themselves in consequence of their motion. A similar effect of the acids was shown by A.D. Waller in the case of the response of nerve to stimuli. The writer observed many years ago that winged male and female ants are positively helioptropic and that their heliotropic sensitiveness increases and reaches its maximum towards the period of nuptial flight. Since the workers show no heliotropism it looks as if an internal secretion from the sexual glands were the cause of their heliotropic sensitiveness. V. Kellogg has observed that bees also become intensely positively heliotropic at the period of their wedding flight, in fact so much so that by letting light fall into the observation hive from above, the bees are prevented from leaving the hive through the exit at the lower end. We notice also the reverse phenomenon, namely, that chemical changes produced in the animal destroy its heliotropism. The caterpillars of Porthesia chrysorrhoea are very strongly positively heliotropic when they are first aroused from their winter sleep. This heliotropic sensitiveness lasts only as long as they are not fed. If they are kept permanently without food they remain permanently positively heliotropic until they die from starvation. It is to be inferred that as soon as these animals take up food, a substance or substances are formed in their bodies which diminish or annihilate their heliotropic sensitiveness. The heliotropism of animals is identical with the heliotropism of plants. The writer has shown that the experiments on the effect of acids on the heliotropism of copepods can be repeated with the same result in Volvox. It is therefore erroneous to try to explain these heliotropic reactions of animals on the basis of peculiarities (e.g. vision) which are not found in plants. We may briefly discuss the question of the transmission through the sex cells of such instincts as are based upon heliotropism. This problem reduces itself simply to that of the method whereby the gametes transmit heliotropism to the larvae or to the adult. The writer has expressed the idea that all that is necessary for this transmission is the presence in the eyes (or in the skin) of the animal of a photo-sensitive substance. For the transmission of this the gametes need not contain anything more than a catalyser or ferment for the synthesis of the photo-sensitive substance in the body of the animal. What has been said in regard to animal heliotropism might, if space permitted, be extended, mutatis mutandis, to geotropism and stereotropism. (c) THE TROPIC REACTIONS OF CERTAIN TISSUE-CELLS AND THE MORPHOGENETIC EFFECTS OF THESE REACTIONS. Since plant-cells show heliotropic reactions identical with those of animals, it is not surprising that certain tissue-cells also show reactions which belong to the class of tropisms. These reactions of tissue-cells are of special interest by reason of their bearing upon the inheritance of morphological characters. An example of this is found in the tiger-like marking of the yolk-sac of the embryo of Fundulus and in the marking of the young fish itself. The writer found that the former is entirely, and the latter at least in part, due to the creeping of the chromatophores upon the blood-vessels. The chromatophores are at first scattered irregularly over the yolk-sac and show their characteristic ramifications. There is at that time no definite relation between blood-vessels and chromatophores. As soon as a ramification of a chromatophore comes in contact with a blood-vessel the whole mass of the chromatophore creeps gradually on the blood-vessel and forms a complete sheath around the vessel, until finally all the chromatophores form a sheath around the vessels and no more pigment cells are found in the meshes between the vessels. Nobody who has not actually watched the process of the creeping of the chromatophores upon the blood-vessels would anticipate that the tiger-like colouration of the yolk-sac in the later stages of the development was brought about in this way. Similar facts can be observed in regard to the first marking of the embryo itself. The writer is inclined to believe that we are here dealing with a case of chemotropism, and that the oxygen of the blood may be the cause of the spreading of the chromatophores around the blood-vessels. Certain observations seem to indicate the possibility that in the adult the chromatophores have, in some forms at least, a more rigid structure and are prevented from acting in the way indicated. It seems to the writer that such observations as those made on Fundulus might simplify the problem of the hereditary transmission of certain markings. Driesch has found that a tropism underlies the arrangement of the skeleton in the pluteus larvae of the sea-urchin. The position of this skeleton is predetermined by the arrangement of the mesenchyme cells, and Driesch has shown that these cells migrate actively to the place of their destination, possibly led there under the influence of certain chemical substances. When Driesch scattered these cells mechanically before their migration, they nevertheless reached their destination. In the developing eggs of insects the nuclei, together with some cytoplasm, migrate to the periphery of the egg. Herbst pointed out that this might be a case of chemotropism, caused by the oxygen surrounding the egg. The writer has expressed the opinion that the formation of the blastula may be caused generally by a tropic reaction of the blastomeres, the latter being forced by an outside influence to creep to the surface of the egg. These examples may suffice to indicate that the arrangement of definite groups of cells and the morphological effects resulting therefrom may be determined by forces lying outside the cells. Since these forces are ubiquitous and constant it appears as if we were dealing exclusively with the influence of a gamete; while in reality all that it is necessary for the gamete to transmit is a certain form of irritability. (d) FACTORS WHICH DETERMINE PLACE AND TIME FOR THE DEPOSITION OF EGGS. For the preservation of species the instinct of animals to lay their eggs in places in which the young larvae find their food and can develop is of paramount importance. A simple example of this instinct is the fact that the common fly lays its eggs on putrid material which serves as food for the young larvae. When a piece of meat and of fat of the same animal are placed side by side, the fly will deposit its eggs upon the meat on which the larvae can grow, and not upon the fat, on which they would starve. Here we are dealing with the effect of a volatile nitrogenous substance which reflexly causes the peristaltic motions for the laying of the egg in the female fly. Kammerer has investigated the conditions for the laying of eggs in two forms of salamanders, e.g. Salamandra atra and S. maculosa. In both forms the eggs are fertilised in the body and begin to develop in the uterus. Since there is room only for a few larvae in the uterus, a large number of eggs perish and this number is the greater the longer the period of gestation. It thus happens that when the animals retain their eggs a long time, very few young ones are born; and these are in a rather advanced stage of development, owing to the long time which elapsed since they were fertilised. When the animal lays its eggs comparatively soon after copulation, many eggs (from 12 to 72) are produced and the larvae are of course in an early stage of development. In the early stage the larvae possess gills and can therefore live in water, while in later stages they have no gills and breathe through their lungs. Kammerer showed that both forms of Salamandra can be induced to lay their eggs early or late, according to the physical conditions surrounding them. If they are kept in water or in proximity to water and in a moist atmosphere they have a tendency to lay their eggs earlier and a comparatively high temperature enhances the tendency to shorten the period of gestation. If the salamanders are kept in comparative dryness they show a tendency to lay their eggs rather late and a low temperature enhances this tendency. Since Salamandra atra is found in rather dry alpine regions with a relatively low temperature and Salamandra maculosa in lower regions with plenty of water and a higher temperature, the fact that S. atra bears young which are already developed and beyond the stage of aquatic life, while S. maculosa bears young ones in an earlier stage, has been termed adaptation. Kammerer's experiments, however, show that we are dealing with the direct effects of definite outside forces. While we may speak of adaptation when all or some of the variables which determine a reaction are unknown, it is obviously in the interest of further scientific progress to connect cause and effect directly whenever our knowledge allows us to do so. VII. CONCLUDING REMARKS. The discovery of De Vries, that new species may arise by mutation and the wide if not universal applicability of Mendel's Law to phenomena of heredity, as shown especially by Bateson and his pupils, must, for the time being, if not permanently, serve as a basis for theories of evolution. These discoveries place before the experimental biologist the definite task of producing mutations by physico-chemical means. It is true that certain authors claim to have succeeded in this, but the writer wishes to apologise to these authors for his inability to convince himself of the validity of their claims at the present moment. He thinks that only continued breeding of these apparent mutants through several generations can afford convincing evidence that we are here dealing with mutants rather than with merely pathological variations. What was said in regard to the production of new species by physico-chemical means may be repeated with still more justification in regard to the second problem of transformation, namely the making of living from inanimate matter. The purely morphological imitations of bacteria or cells which physicists have now and then proclaimed as artificially produced living beings; or the plays on words by which, e.g. the regeneration of broken crystals and the regeneration of lost limbs by a crustacean were declared identical, will not appeal to the biologist. We know that growth and development in animals and plants are determined by definite although complicated series of catenary chemical reactions, which result in the synthesis of a DEFINITE compound or group of compounds, namely, NUCLEINS. The nucleins have the peculiarity of acting as ferments or enzymes for their own synthesis. Thus a given type of nucleus will continue to synthesise other nuclein of its own kind. This determines the continuity of a species; since each species has, probably, its own specific nuclein or nuclear material. But it also shows us that whoever claims to have succeeded in making living matter from inanimate will have to prove that he has succeeded in producing nuclein material which acts as a ferment for its own synthesis and thus reproduces itself. Nobody has thus far succeeded in this, although nothing warrants us in taking it for granted that this task is beyond the power of science. XV. THE VALUE OF COLOUR IN THE STRUGGLE FOR LIFE. By E.B. Poulton. Hope Professor of Zoology in the University of Oxford. INTRODUCTION. The following pages have been written almost entirely from the historical stand-point. Their principal object has been to give some account of the impressions produced on the mind of Darwin and his great compeer Wallace by various difficult problems suggested by the colours of living nature. In order to render the brief summary of Darwin's thoughts and opinions on the subject in any way complete, it was found necessary to say again much that has often been said before. No attempt has been made to display as a whole the vast contribution of Wallace; but certain of its features are incidentally revealed in passages quoted from Darwin's letters. It is assumed that the reader is familiar with the well-known theories of Protective Resemblance, Warning Colours, and Mimicry both Batesian and Mullerian. It would have been superfluous to explain these on the present occasion; for a far more detailed account than could have been attempted in these pages has recently appeared. (Poulton, "Essays on Evolution" Oxford, 1908, pages 293-382.) Among the older records I have made a point of bringing together the principal observations scattered through the note-books and collections of W.J. Burchell. These have never hitherto found a place in any memoir dealing with the significance of the colours of animals. INCIDENTAL COLOURS. Darwin fully recognised that the colours of living beings are not necessarily of value as colours, but that they may be an incidental result of chemical or physical structure. Thus he wrote to T. Meehan, Oct. 9, 1874: "I am glad that you are attending to the colours of dioecious flowers; but it is well to remember that their colours may be as unimportant to them as those of a gall, or, indeed, as the colour of an amethyst or ruby is to these gems." ("More Letters of Charles Darwin", Vol. I. pages 354, 355. See also the admirable account of incidental colours in "Descent of Man" (2nd edition), 1874, pages 261, 262.) Incidental colours remain as available assets of the organism ready to be turned to account by natural selection. It is a probable speculation that all pigmentary colours were originally incidental; but now and for immense periods of time the visible tints of animals have been modified and arranged so as to assist in the struggle with other organisms or in courtship. The dominant colouring of plants, on the other hand, is an essential element in the paramount physiological activity of chlorophyll. In exceptional instances, however, the shapes and visible colours of plants may be modified in order to promote concealment. TELEOLOGY AND ADAPTATION. In the department of Biology which forms the subject of this essay, the adaptation of means to an end is probably more evident than in any other; and it is therefore of interest to compare, in a brief introductory section, the older with the newer teleological views. The distinctive feature of Natural Selection as contrasted with other attempts to explain the process of Evolution is the part played by the struggle for existence. All naturalists in all ages must have known something of the operations of "Nature red in tooth and claw"; but it was left for this great theory to suggest that vast extermination is a necessary condition of progress, and even of maintaining the ground already gained. Realising that fitness is the outcome of this fierce struggle, thus turned to account for the first time, we are sometimes led to associate the recognition of adaptation itself too exclusively with Natural Selection. Adaptation had been studied with the warmest enthusiasm nearly forty years before this great theory was given to the scientific world, and it is difficult now to realise the impetus which the works of Paley gave to the study of Natural History. That they did inspire the naturalists of the early part of the last century is clearly shown in the following passages. In the year 1824 the Ashmolean Museum at Oxford was intrusted to the care of J.S. Duncan of New College. He was succeeded in this office by his brother, P.B. Duncan, of the same College, author of a History of the Museum, which shows very clearly the influence of Paley upon the study of nature, and the dominant position given to his teachings: "Happily at this time (1824) a taste for the study of natural history had been excited in the University by Dr Paley's very interesting work on Natural Theology, and the very popular lectures of Dr Kidd on Comparative Anatomy, and Dr Buckland on Geology." In the arrangement of the contents of the Museum the illustration of Paley's work was given the foremost place by J.S. Duncan: "The first division proposes to familiarize the eye to those relations of all natural objects which form the basis of argument in Dr Paley's Natural Theology; to induce a mental habit of associating the view of natural phenomena with the conviction that they are the media of Divine manifestation; and by such association to give proper dignity to every branch of natural science." (From "History and Arrangement of the Ashmolean Museum" by P.B. Duncan: see pages vi, vii of "A Catalogue of the Ashmolean Museum", Oxford, 1836.) The great naturalist, W.J. Burchell, in his classical work shows the same recognition of adaptation in nature at a still earlier date. Upon the subject of collections he wrote ("Travels in the Interior of Southern Africa", London, Vol. I. 1822, page 505. The references to Burchell's observations in the present essay are adapted from the author's article in "Report of the British and South African Associations", 1905, Vol. III. pages 57-110.): "It must not be supposed that these charms (the pleasures of Nature) are produced by the mere discovery of new objects: it is the harmony with which they have been adapted by the Creator to each other, and to the situations in which they are found, which delights the observer in countries where Art has not yet introduced her discords." The remainder of the passage is so admirable that I venture to quote it: "To him who is satisfied with amassing collections of curious objects, simply for the pleasure of possessing them, such objects can afford, at best, but a childish gratification, faint and fleeting; while he who extends his view beyond the narrow field of nomenclature, beholds a boundless expanse, the exploring of which is worthy of the philosopher, and of the best talents of a reasonable being." On September 14, 1811, Burchell was at Zand Valley (Vlei), or Sand Pool, a few miles south-west of the site of Prieska, on the Orange River. Here he found a Mesembryanthemum (M. turbiniforme, now M. truncatum) and also a "Gryllus" (Acridian), closely resembling the pebbles with which their locality was strewn. He says of both of these, "The intention of Nature, in these instances, seems to have been the same as when she gave to the Chameleon the power of accommodating its color, in a certain degree, to that of the object nearest to it, in order to compensate for the deficiency of its locomotive powers. By their form and colour, this insect may pass unobserved by those birds, which otherwise would soon extirpate a species so little able to elude its pursuers, and this juicy little Mesembryanthemum may generally escape the notice of cattle and wild animals." (Loc. cit. pages 310, 311. See Sir William Thiselton-Dyer "Morphological Notes", XI.; "Protective Adaptations", I.; "Annals of Botany", Vol. XX. page 124. In plates VII., VIII. and IX. accompanying this article the author represents the species observed by Burchell, together with others in which analogous adaptations exist. He writes: "Burchell was clearly on the track on which Darwin reached the goal. But the time had not come for emancipation from the old teleology. This, however, in no respect detracts from the merit or value of his work. For, as Huxley has pointed out ("Life and Letters of Thomas Henry Huxley", London, 1900, I. page 457), the facts of the old teleology are immediately transferable to Darwinism, which simply supplies them with a natural in place of a supernatural explanation.") Burchell here seems to miss, at least in part, the meaning of the relationship between the quiescence of the Acridian and its cryptic colouring. Quiescence is an essential element in the protective resemblance to a stone--probably even more indispensable than the details of the form and colouring. Although Burchell appears to overlook this point he fully recognised the community between protection by concealment and more aggressive modes of defence; for, in the passage of which a part is quoted above, he specially refers to some earlier remarks on page 226 of his Vol. I. We here find that even when the oxen were resting by the Juk rivier (Yoke river), on July 19, 1811, Burchell observed "Geranium spinosum, with a fleshy stem and large white flowers...; and a succulent species of Pelargonium... so defended by the old panicles, grown to hard woody thorns, that no cattle could browze upon it." He goes on to say, "In this arid country, where every juicy vegetable would soon be eaten up by the wild animals, the Great Creating Power, with all-provident wisdom, has given to such plants either an acrid or poisonous juice, or sharp thorns, to preserve the species from annihilation... " All these modes of defence, especially adapted to a desert environment, have since been generally recognised, and it is very interesting to place beside Burchell's statement the following passage from a letter written by Darwin, Aug. 7, 1868, to G.H. Lewes; "That Natural Selection would tend to produce the most formidable thorns will be admitted by every one who has observed the distribution in South America and Africa (vide Livingstone) of thorn-bearing plants, for they always appear where the bushes grow isolated and are exposed to the attacks of mammals. Even in England it has been noticed that all spine-bearing and sting-bearing plants are palatable to quadrupeds, when the thorns are crushed." ("More Letters", I. page 308.) ADAPTATION AND NATURAL SELECTION. I have preferred to show the influence of the older teleology upon Natural History by quotations from a single great and insufficiently appreciated naturalist. It might have been seen equally well in the pages of Kirby and Spence and those of many other writers. If the older naturalists who thought and spoke with Burchell of "the intention of Nature" and the adaptation of beings "to each other, and to the situations in which they are found," could have conceived the possibility of evolution, they must have been led, as Darwin was, by the same considerations to Natural Selection. This was impossible for them, because the philosophy which they followed contemplated the phenomena of adaptation as part of a static immutable system. Darwin, convinced that the system is dynamic and mutable, was prevented by these very phenomena from accepting anything short of the crowning interpretation offered by Natural Selection. ("I had always been much struck by such adaptations (e.g. woodpecker and tree-frog for climbing, seeds for dispersal), and until these could be explained it seemed to me almost useless to endeavour to prove by indirect evidence that species have been modified." "Autobiography" in "Life and Letters of Charles Darwin", Vol. I. page 82. The same thought is repeated again and again in Darwin's letters to his friends. It is forcibly urged in the Introduction to the "Origin" (1859), page 3.) And the birth of Darwin's unalterable conviction that adaptation is of dominant importance in the organic world,--a conviction confirmed and ever again confirmed by his experience as a naturalist--may probably be traced to the influence of the great theologian. Thus Darwin, speaking of his Undergraduate days, tells us in his "Autobiography" that the logic of Paley's "Evidences of Christianity" and "Moral Philosophy" gave him as much delight as did Euclid. "The careful study of these works, without attempting to learn any part by rote, was the only part of the academical course which, as I then felt and as I still believe, was of the least use to me in the education of my mind. I did not at that time trouble myself about Paley's premises; and taking these on trust, I was charmed and convinced by the long line of argumentation." ("Life and Letters", I. page 47.) When Darwin came to write the "Origin" he quoted in relation to Natural Selection one of Paley's conclusions. "No organ will be formed, as Paley has remarked, for the purpose of causing pain or for doing an injury to its possessor." ("Origin of Species" (1st edition) 1859, page 201.) The study of adaptation always had for Darwin, as it has for many, a peculiar charm. His words, written Nov. 28, 1880, to Sir W. Thiselton-Dyer, are by no means inapplicable to-day: "Many of the Germans are very contemptuous about making out use of organs; but they may sneer the souls out of their bodies, and I for one shall think it the most interesting part of natural history." ("More Letters" II. page 428.) PROTECTIVE AND AGGRESSIVE RESEMBLANCE: PROCRYPTIC AND ANTICRYPTIC COLOURING. Colouring for the purpose of concealment is sometimes included under the head Mimicry, a classification adopted by H.W. Bates in his classical paper. Such an arrangement is inconvenient, and I have followed Wallace in keeping the two categories distinct. The visible colours of animals are far more commonly adapted for Protective Resemblance than for any other purpose. The concealment of animals by their colours, shapes and attitudes, must have been well known from the period at which human beings first began to take an intelligent interest in Nature. An interesting early record is that of Samuel Felton, who (Dec. 2, 1763) figured and gave some account of an Acridian (Phyllotettix) from Jamaica. Of this insect he says "THE THORAX is like a leaf that is raised perpendicularly from the body." ("Phil. Trans. Roy. Soc." Vol. LIV. Tab. VI. page 55.) Both Protective and Aggressive Resemblances were appreciated and clearly explained by Erasmus Darwin in 1794: "The colours of many animals seem adapted to their purposes of concealing themselves either to avoid danger, or to spring upon their prey." ("Zoonomia", Vol. I. page 509, London, 1794.) Protective Resemblance of a very marked and beautiful kind is found in certain plants, inhabitants of desert areas. Examples observed by Burchell almost exactly a hundred years ago have already been mentioned. In addition to the resemblance to stones Burchell observed, although he did not publish the fact, a South African plant concealed by its likeness to the dung of birds. (Sir William Thiselton-Dyer has suggested the same method of concealment ("Annals of Botany", Vol. XX. page 123). Referring to Anacampseros papyracea, figured on plate IX., the author says of its adaptive resemblance: "At the risk of suggesting one perhaps somewhat far-fetched, I must confess that the aspect of the plant always calls to my mind the dejecta of some bird, and the more so owing to the whitening of the branches towards the tips" (loc. cit. page 126). The student of insects, who is so familiar with this very form of protective resemblance in larvae, and even perfect insects, will not be inclined to consider the suggestion far-fetched.) The observation is recorded in one of the manuscript journals kept by the great explorer during his journey. I owe the opportunity of studying it to the kindness of Mr Francis A. Burchell of the Rhodes University College, Grahamstown. The following account is given under the date July 5, 1812, when Burchell was at the Makkwarin River, about half-way between the Kuruman River and Litakun the old capital of the Bachapins (Bechuanas): "I found a curious little Crassula (not in flower) so snow white, that I should never has (have) distinguished it from the white limestones... It was an inch high and a little branchy,... and was at first mistaken for the dung of birds of the passerine order. I have often had occasion to remark that in stony place(s) there grow many small succulent plants and abound insects (chiefly Grylli) which have exactly the same colour as the ground and must for ever escape observation unless a person sit on the ground and observe very attentively." The cryptic resemblances of animals impressed Darwin and Wallace in very different degrees, probably in part due to the fact that Wallace's tropical experiences were so largely derived from the insect world, in part to the importance assigned by Darwin to Sexual Selection "a subject which had always greatly interested me," as he says in his "Autobiography", ("Life and Letters", Vol. I. page 94.) There is no reference to Cryptic Resemblance in Darwin's section of the Joint Essay, although he gives an excellent short account of Sexual Selection (see page 295). Wallace's section on the other hand contains the following statement: "Even the peculiar colours of many animals, especially insects, so closely resembling the soil or the leaves or the trunks on which they habitually reside, are explained on the same principle; for though in the course of ages varieties of many tints may have occurred, YET THOSE RACES HAVING COLOURS BEST ADAPTED TO CONCEALMENT FROM THEIR ENEMIES WOULD INEVITABLY SURVIVE THE LONGEST." ("Journ. Proc. Linn. Soc." Vol. III. 1859, page 61. The italics are Wallace's.) It would occupy too much space to attempt any discussion of the difference between the views of these two naturalists, but it is clear that Darwin, although fully believing in the efficiency of protective resemblance and replying to St George Mivart's contention that Natural Selection was incompetent to produce it ("Origin" (6th edition) London, 1872, pages 181, 182; see also page 66.), never entirely agreed with Wallace's estimate of its importance. Thus the following extract from a letter to Sir Joseph Hooker, May 21, 1868, refers to Wallace: "I find I must (and I always distrust myself when I differ from him) separate rather widely from him all about birds' nests and protection; he is riding that hobby to death." ("More Letters", I. page 304.) It is clear from the account given in "The Descent of Man", (London, 1874, pages 452-458. See also "Life and Letters", III. pages 123-125, and "More Letters", II. pages 59-63, 72-74, 76-78, 84-90, 92, 93.), that the divergence was due to the fact that Darwin ascribed more importance to Sexual Selection than did Wallace, and Wallace more importance to Protective Resemblance than Darwin. Thus Darwin wrote to Wallace, Oct. 12 and 13, 1867: "By the way, I cannot but think that you push protection too far in some cases, as with the stripes on the tiger." ("More Letters", I. page 283.) Here too Darwin was preferring the explanation offered by Sexual Selection ("Descent of Man" (2nd edition) 1874, pages 545, 546.), a preference which, considering the relation of the colouring of the lion and tiger to their respective environments, few naturalists will be found to share. It is also shown that Darwin contemplated the possibility of cryptic colours such as those of Patagonian animals being due to sexual selection influenced by the aspect of surrounding nature. Nearly a year later Darwin in his letter of May 5, 1868?, expressed his agreement with Wallace's views: "Expect that I should put sexual selection as an equal, or perhaps as even a more important agent in giving colour than Natural Selection for protection." ("More Letters", II. pages 77, 78.) The conclusion expressed in the above quoted passage is opposed by the extraordinary development of Protective Resemblance in the immature stages of animals, especially insects. It must not be supposed, however, that Darwin ascribed an unimportant role to Cryptic Resemblances, and as observations accumulated he came to recognise their efficiency in fresh groups of the animal kingdom. Thus he wrote to Wallace, May 5, 1867: "Haeckel has recently well shown that the transparency and absence of colour in the lower oceanic animals, belonging to the most different classes, may be well accounted for on the principle of protection." ("More Letters", II. page 62. See also "Descent of Man", page 261.) Darwin also admitted the justice of Professor E.S. Morse's contention that the shells of molluscs are often adaptively coloured. ("More Letters", II. page 95.) But he looked upon cryptic colouring and also mimicry as more especially Wallace's departments, and sent to him and to Professor Meldola observations and notes bearing upon these subjects. Thus the following letter given to me by Dr A.R. Wallace and now, by kind permission, published for the first time, accompanied a photograph of the chrysalis of Papilio sarpedon choredon, Feld., suspended from a leaf of its food-plant: July 9th, Down, Beckenham, Kent. My Dear Wallace, Dr G. Krefft has sent me the enclosed from Sydney. A nurseryman saw a caterpillar feeding on a plant and covered the whole up, but when he searched for the cocoon (pupa), was long before he could find it, so good was its imitation in colour and form to the leaf to which it was attached. I hope that the world goes well with you. Do not trouble yourself by acknowledging this. Ever yours Ch. Darwin. Another deeply interesting letter of Darwin's bearing upon protective resemblance, has only recently been shown to me by my friend Professor E.B. Wilson, the great American Cytologist. With his kind consent and that of Mr Francis Darwin, this letter, written four months before Darwin's death on April 19, 1882, is reproduced here (The letter is addressed: "Edmund B. Wilson, Esq., Assistant in Biology, John Hopkins University, Baltimore Md, U. States."): December 21, 1881. Dear Sir, I thank you much for having taken so much trouble in describing fully your interesting and curious case of mimickry. I am in the habit of looking through many scientific Journals, and though my memory is now not nearly so good as it was, I feel pretty sure that no such case as yours has been described (amongst the nudibranch) molluscs. You perhaps know the case of a fish allied to Hippocampus, (described some years ago by Dr Gunther in "Proc. Zoolog. Socy.") which clings by its tail to sea-weeds, and is covered with waving filaments so as itself to look like a piece of the same sea-weed. The parallelism between your and Dr Gunther's case makes both of them the more interesting; considering how far a fish and a mollusc stand apart. It would be difficult for anyone to explain such cases by the direct action of the environment.--I am glad that you intend to make further observations on this mollusc, and I hope that you will give a figure and if possible a coloured figure. With all good wishes from an old brother naturalist, I remain, Dear Sir, Yours faithfully, Charles Darwin. Professor E.B. Wilson has kindly given the following account of the circumstances under which he had written to Darwin: "The case to which Darwin's letter refers is that of the nudibranch mollusc Scyllaea, which lives on the floating Sargassum and shows a really astonishing resemblance to the plant, having leaf-shaped processes very closely similar to the fronds of the sea-weed both in shape and in colour. The concealment of the animal may be judged from the fact that we found the animal quite by accident on a piece of Sargassum that had been in a glass jar in the laboratory for some time and had been closely examined in the search for hydroids and the like without disclosing the presence upon it of two large specimens of the Scyllaea (the animal, as I recall it, is about two inches long). It was first detected by its movements alone, by someone (I think a casual visitor to the laboratory) who was looking closely at the Sargassum and exclaimed 'Why, the sea-weed is moving its leaves'! We found the example in the summer of 1880 or 1881 at Beaufort, N.C., where the Johns Hopkins laboratory was located for the time being. It must have been seen by many others, before or since. "I wrote and sent to Darwin a short description of the case at the suggestion of Brooks, with whom I was at the time a student. I was, of course, entirely unknown to Darwin (or to anyone else) and to me the principal interest of Darwin's letter is the evidence that it gives of his extraordinary kindness and friendliness towards an obscure youngster who had of course absolutely no claim upon his time or attention. The little incident made an indelible impression upon my memory and taught me a lesson that was worth learning." VARIABLE PROTECTIVE RESEMBLANCE. The wonderful power of rapid colour adjustment possessed by the cuttle-fish was observed by Darwin in 1832 at St Jago, Cape de Verd Islands, the first place visited during the voyage of the "Beagle". From Rio he wrote to Henslow, giving the following account of his observations, May 18, 1832: "I took several specimens of an Octopus which possessed a most marvellous power of changing its colours, equalling any chameleon, and evidently accommodating the changes to the colour of the ground which it passed over. Yellowish green, dark brown, and red, were the prevailing colours; this fact appears to be new, as far as I can find out." ("Life and Letters", I. pages 235, 236. See also Darwin's "Journal of Researches", 1876, pages 6-8, where a far more detailed account is given together with a reference to "Encycl. of Anat. and Physiol.") Darwin was well aware of the power of individual colour adjustment, now known to be possessed by large numbers of lepidopterous pupae and larvae. An excellent example was brought to his notice by C.V. Riley ("More Letters" II, pages 385, 386.), while the most striking of the early results obtained with the pupae of butterflies--those of Mrs M.E. Barber upon Papilio nireus--was communicated by him to the Entomological Society of London. ("Trans. Ent. Soc. Lond." 1874, page 519. See also "More Letters", II. page 403.) It is also necessary to direct attention to C.W. Beebe's ("Zoologica: N.Y. Zool. Soc." Vol. I. No. 1, Sept. 25, 1907: "Geographic variation in birds with especial reference to the effects of humidity".) recent discovery that the pigmentation of the plumage of certain birds is increased by confinement in a superhumid atmosphere. In Scardafella inca, on which the most complete series of experiments was made, the changes took place only at the moults, whether normal and annual or artificially induced at shorter periods. There was a corresponding increase in the choroidal pigment of the eye. At a certain advanced stage of feather pigmentation a brilliant iridescent bronze or green tint made its appearance on those areas where iridescence most often occurs in allied genera. Thus in birds no less than in insects, characters previously regarded as of taxonomic value, can be evoked or withheld by the forces of the environment. WARNING OR APOSEMATIC COLOURS. From Darwin's description of the colours and habits it is evident that he observed, in 1833, an excellent example of warning colouring in a little South American toad (Phryniscus nigricans). He described it in a letter to Henslow, written from Monte Video, Nov. 24, 1832: "As for one little toad, I hope it may be new, that it may be christened 'diabolicus.' Milton must allude to this very individual when he talks of 'squat like a toad'; its colours are by Werner ("Nomenclature of Colours", 1821) ink black, vermilion red and buff orange." ("More Letters", I. page 12.) In the "Journal of Researches" (1876, page 97.) its colours are described as follows: "If we imagine, first, that it had been steeped in the blackest ink, and then, when dry, allowed to crawl over a board, freshly painted with the brightest vermilion, so as to colour the soles of its feet and parts of its stomach, a good idea of its appearance will be gained." "Instead of being nocturnal in its habits, as other toads are, and living in damp obscure recesses, it crawls during the heat of the day about the dry sand-hillocks and arid plains,... " The appearance and habits recall T. Belt's well-known description of the conspicuous little Nicaraguan frog which he found to be distasteful to a duck. ("The Naturalist in Nicaragua" (2nd edition) London, 1888, page 321.) The recognition of the Warning Colours of caterpillars is due in the first instance to Darwin, who, reflecting on Sexual Selection, was puzzled by the splendid colours of sexually immature organisms. He applied to Wallace "who has an innate genius for solving difficulties." ("Descent of Man", page 325. On this and the following page an excellent account of the discovery will be found, as well as in Wallace's "Natural Selection", London, 1875, pages 117-122.) Darwin's original letter exists ("Life and Letters", III. pages 93, 94.), and in it we are told that he had taken the advice given by Bates: "You had better ask Wallace." After some consideration Wallace replied that he believed the colours of conspicuous caterpillars and perfect insects were a warning of distastefulness and that such forms would be refused by birds. Darwin's reply ("Life and Letters", III. pages 94, 95.) is extremely interesting both for its enthusiasm at the brilliancy of the hypothesis and its caution in acceptance without full confirmation: "Bates was quite right; you are the man to apply to in a difficulty. I never heard anything more ingenious than your suggestion, and I hope you may be able to prove it true. That is a splendid fact about the white moths (A single white moth which was rejected by young turkeys, while other moths were greedily devoured: "Natural Selection", 1875, page 78.); it warms one's very blood to see a theory thus almost proved to be true." Two years later the hypothesis was proved to hold for caterpillars of many kinds by J. Jenner Weir and A.G. Butler, whose observations have since been abundantly confirmed by many naturalists. Darwin wrote to Weir, May 13, 1869: "Your verification of Wallace's suggestion seems to me to amount to quite a discovery." ("More Letters", II. page 71 (footnote).) RECOGNITION OR EPISEMATIC CHARACTERS. This principle does not appear to have been in any way foreseen by Darwin, although he draws special attention to several elements of pattern which would now be interpreted by many naturalists as epismes. He believed that the markings in question interfered with the cryptic effect, and came to the conclusion that, even when common to both sexes, they "are the result of sexual selection primarily applied to the male." ("Descent of Man", page 544.) The most familiar of all recognition characters was carefully explained by him, although here too explained as an ornamental feature now equally transmitted to both sexes: "The hare on her form is a familiar instance of concealment through colour; yet this principle partly fails in a closely-allied species, the rabbit, for when running to its burrow, it is made conspicuous to the sportsman, and no doubt to all beasts of prey, by its upturned white tail." ("Descent of Man", page 542.) The analogous episematic use of the bright colours of flowers to attract insects for effecting cross-fertilisation and of fruits to attract vertebrates for effecting dispersal is very clearly explained in the "Origin". (Edition 1872, page 161. For a good example of Darwin's caution in dealing with exceptions see the allusion to brightly coloured fruit in "More Letters", II. page 348.) It is not, at this point, necessary to treat sematic characters at any greater length. They will form the subject of a large part of the following section, where the models of Batesian (Pseudaposematic) mimicry are considered as well as the Mullerian (Synaposematic) combinations of Warning Colours. MIMICRY,--BATESIAN OR PSEUDAPOSEMATIC, MULLERIAN OR SYNAPOSEMATIC. The existence of superficial resemblances between animals of various degrees of affinity must have been observed for hundreds of years. Among the early examples, the best known to me have been found in the manuscript note-books and collections of W.J. Burchell, the great traveller in Africa (1810-15) and Brazil (1825-30). The most interesting of his records on this subject are brought together in the following paragraphs. Conspicuous among well-defended insects are the dark steely or iridescent greenish blue fossorial wasps or sand-wasps, Sphex and the allied genera. Many Longicorn beetles mimic these in colour, slender shape of body and limbs, rapid movements, and the readiness with which they take to flight. On Dec. 21, 1812, Burchell captured one such beetle (Promeces viridis) at Kosi Fountain on the journey from the source of the Kuruman River to Klaarwater. It is correctly placed among the Longicorns in his catalogue, but opposite to its number is the comment "Sphex! totus purpureus." In our own country the black-and-yellow colouring of many stinging insects, especially the ordinary wasps, affords perhaps the commonest model for mimicry. It is reproduced with more or less accuracy on moths, flies and beetles. Among the latter it is again a Longicorn which offers one of the best-known, although by no means one of the most perfect, examples. The appearance of the well-known "wasp-beetle" (Clytus arietis) in the living state is sufficiently suggestive to prevent the great majority of people from touching it. In Burchell's Brazilian collection there is a nearly allied species (Neoclytus curvatus) which appears to be somewhat less wasp-like than the British beetle. The specimen bears the number "1188," and the date March 27, 1827, when Burchell was collecting in the neighbourhood of San Paulo. Turning to the corresponding number in the Brazilian note-book we find this record: "It runs rapidly like an ichneumon or wasp, of which it has the appearance." The formidable, well-defended ants are as freely mimicked by other insects as the sand-wasps, ordinary wasps and bees. Thus on February 17, 1901, Guy A.K. Marshall captured, near Salisbury, Mashonaland, three similar species of ants (Hymenoptera) with a bug (Hemiptera) and a Locustid (Orthoptera), the two latter mimicking the former. All the insects, seven in number, were caught on a single plant, a small bushy vetch. ("Trans. Ent. Soc. Lond." 1902, page 535, plate XIX. figs. 53-59.) This is an interesting recent example from South Africa, and large numbers of others might be added--the observations of many naturalists in many lands; but nearly all of them known since that general awakening of interest in the subject which was inspired by the great hypotheses of H.W. Bates and Fritz Muller. We find, however, that Burchell had more than once recorded the mimetic resemblance to ants. An extremely ant-like bug (the larva of a species of Alydus) in his Brazilian collection is labelled "1141," with the date December 8, 1826, when Burchell was at the Rio das Pedras, Cubatao, near Santos. In the note-book the record is as follows: "1141 Cimex. I collected this for a Formica." Some of the chief mimics of ants are the active little hunting spiders belonging to the family Attidae. Examples have been brought forward during many recent years, especially by my friends Dr and Mrs Peckham, of Milwaukee, the great authorities on this group of Araneae. Here too we find an observation of the mimetic resemblance recorded by Burchell, and one which adds in the most interesting manner to our knowledge of the subject. A fragment, all that is now left, of an Attid spider, captured on June 30, 1828, at Goyaz, Brazil, bears the following note, in this case on the specimen and not in the note-book: "Black... runs and seems like an ant with large extended jaws." My friend Mr R.I. Pocock, to whom I have submitted the specimen, tells me that it is not one of the group of species hitherto regarded as ant-like, and he adds, "It is most interesting that Burchell should have noticed the resemblance to an ant in its movements. This suggests that the perfect imitation in shape, as well as in movement, seen in many species was started in forms of an appropriate size and colour by the mimicry of movement alone." Up to the present time Burchell is the only naturalist who has observed an example which still exhibits this ancestral stage in the evolution of mimetic likeness. Following the teachings of his day, Burchell was driven to believe that it was part of the fixed and inexorable scheme of things that these strange superficial resemblances existed. Thus, when he found other examples of Hemipterous mimics, including one (Luteva macrophthalma) with "exactly the manners of a Mantis," he added the sentence, "In the genus Cimex (Linn.) are to be found the outward resemblances of insects of many other genera and orders" (February 15, 1829). Of another Brazilian bug, which is not to be found in his collection, and cannot therefore be precisely identified, he wrote: "Cimex... Nature seems to have intended it to imitate a Sphex, both in colour and the rapid palpitating and movement of the antennae" (November 15, 1826). At the same time it is impossible not to feel the conviction that Burchell felt the advantage of a likeness to stinging insects and to aggressive ants, just as he recognised the benefits conferred on desert plants by spines and by concealment. Such an interpretation of mimicry was perfectly consistent with the theological doctrines of his day. (See Kirby and Spence, "An Introduction to Entomology" (1st edition), London, Vol. II. 1817, page 223.) The last note I have selected from Burchell's manuscript refers to one of the chief mimics of the highly protected Lycid beetles. The whole assemblage of African insects with a Lycoid colouring forms a most important combination and one which has an interesting bearing upon the theories of Bates and Fritz Muller. This most wonderful set of mimetic forms, described in 1902 by Guy A.K. Marshall, is composed of flower-haunting beetles belonging to the family Lycidae, and the heterogeneous group of varied insects which mimic their conspicuous and simple scheme of colouring. The Lycid beetles, forming the centre or "models" of the whole company, are orange-brown in front for about two-thirds of the exposed surface, black behind for the remaining third. They are undoubtedly protected by qualities which make them excessively unpalatable to the bulk of insect-eating animals. Some experimental proof of this has been obtained by Mr Guy Marshall. What are the forms which surround them? According to the hypothesis of Bates they would be, at any rate mainly, palatable hard-pressed insects which only hold their own in the struggle for life by a fraudulent imitation of the trade-mark of the successful and powerful Lycidae. According to Fritz Muller's hypothesis we should expect that the mimickers would be highly protected, successful and abundant species, which (metaphorically speaking) have found it to their advantage to possess an advertisement, a danger-signal, in common with each other, and in common with the beetles in the centre of the group. How far does the constitution of this wonderful combination--the largest and most complicated as yet known in all the world--convey to us the idea of mimicry working along the lines supposed by Bates or those suggested by Muller? Figures 1 to 52 of Mr Marshall's coloured plate ("Trans. Ent. Soc. Lond." 1902, plate XVIII. See also page 517, where the group is analysed.) represent a set of forty-two or forty-three species or forms of insects captured in Mashonaland, and all except two in the neighbourhood of Salisbury. The combination includes six species of Lycidae; nine beetles of five groups all specially protected by nauseous qualities, Telephoridae, Melyridae, Phytophaga, Lagriidae, Cantharidae; six Longicorn beetles; one Coprid beetle; eight stinging Hymenoptera; three or four parasitic Hymenoptera (Braconidae, a group much mimicked and shown by some experiments to be distasteful); five bugs (Hemiptera, a largely unpalatable group); three moths (Arctiidae and Zygaenidae, distasteful families); one fly. In fact the whole combination, except perhaps one Phytophagous, one Coprid and the Longicorn beetles, and the fly, fall under the hypothesis of Muller and not under that of Bates. And it is very doubtful whether these exceptions will be sustained: indeed the suspicion of unpalatability already besets the Longicorns and is always on the heels,--I should say the hind tarsi--of a Phytophagous beetle. This most remarkable group which illustrates so well the problem of mimicry and the alternative hypotheses proposed for its solution, was, as I have said, first described in 1902. Among the most perfect of the mimetic resemblances in it is that between the Longicorn beetle, Amphidesmus analis, and the Lycidae. It was with the utmost astonishment and pleasure that I found this very resemblance had almost certainly been observed by Burchell. A specimen of the Amphidesmus exists in his collection and it bears "651." Turning to the same number in the African Catalogue we find that the beetle is correctly placed among the Longicorns, that it was captured at Uitenhage on Nov. 18, 1813, and that it was found associated with Lycid beetles in flowers ("consocians cum Lycis 78-87 in floribus"). Looking up Nos. 78-87 in the collection and catalogue, three species of Lycidae are found, all captured on Nov. 18, 1813, at Uitenhage. Burchell recognised the wide difference in affinity, shown by the distance between the respective numbers; for his catalogue is arranged to represent relationships. He observed, what students of mimicry are only just beginning to note and record, the coincidence between model and mimic in time and space and in habits. We are justified in concluding that he observed the close superficial likeness although he does not in this case expressly allude to it. One of the most interesting among the early observations of superficial resemblance between forms remote in the scale of classification was made by Darwin himself, as described in the following passage from his letter to Henslow, written from Monte Video, Aug. 15, 1832: "Amongst the lower animals nothing has so much interested me as finding two species of elegantly coloured true Planaria inhabiting the dewy forest! The false relation they bear to snails is the most extraordinary thing of the kind I have ever seen." ("More Letters", I. page 9.) Many years later, in 1867, he wrote to Fritz Muller suggesting that the resemblance of a soberly coloured British Planarian to a slug might be due to mimicry. ("Life and Letters", III. page 71.) The most interesting copy of Bates's classical memoir on Mimicry ("Contributions to an Insect Fauna of the Amazon Valley". "Trans. Linn. Soc." Vol. XXIII. 1862, page 495.), read before the Linnean Society in 1861, is that given by him to the man who has done most to support and extend the theory. My kind friend has given that copy to me; it bears the inscription: "Mr A.R. Wallace from his old travelling companion the Author." Only a year and a half after the publication of the "Origin", we find that Darwin wrote to Bates on the subject which was to provide such striking evidence of the truth of Natural Selection: "I am glad to hear that you have specially attended to 'mimetic' analogies--a most curious subject; I hope you publish on it. I have for a long time wished to know whether what Dr Collingwood asserts is true--that the most striking cases generally occur between insects inhabiting the same country." (The letter is dated April 4, 1861. "More Letters", I. page 183.) The next letter, written about six months later, reveals the remarkable fact that the illustrious naturalist who had anticipated Edward Forbes in the explanation of arctic forms on alpine heights ("I was forestalled in only one important point, which my vanity has always made me regret, namely, the explanation by means of the Glacial period of the presence of the same species of plants and of some few animals on distant mountain summits and in the arctic regions. This view pleased me so much that I wrote it out in extenso, and I believe that it was read by Hooker some years before E. Forbes published his celebrated memoir on the subject. In the very few points in which we differed, I still think that I was in the right. I have never, of course, alluded in print to my having independently worked out this view." "Autobiography, Life and Letters", I. page 88.), had also anticipated H.W. Bates in the theory of Mimicry: "What a capital paper yours will be on mimetic resemblances! You will make quite a new subject of it. I had thought of such cases as a difficulty; and once, when corresponding with Dr Collingwood, I thought of your explanation; but I drove it from my mind, for I felt that I had not knowledge to judge one way or the other." (The letter is dated Sept. 25, 1861: "More Letters", I. page 197.) Bates read his paper before the Linnean Society, Nov. 21, 1861, and Darwin's impressions on hearing it were conveyed in a letter to the author dated Dec. 3: "Under a general point of view, I am quite convinced (Hooker and Huxley took the same view some months ago) that a philosophic view of nature can solely be driven into naturalists by treating special subjects as you have done. Under a special point of view, I think you have solved one of the most perplexing problems which could be given to solve." ("Life and Letters", II. page 378.) The memoir appeared in the following year, and after reading it Darwin wrote as follows, Nov. 20, 1862: "... In my opinion it is one of the most remarkable and admirable papers I ever read in my life... I am rejoiced that I passed over the whole subject in the "Origin", for I should have made a precious mess of it. You have most clearly stated and solved a wonderful problem... Your paper is too good to be largely appreciated by the mob of naturalists without souls; but, rely on it, that it will have LASTING value, and I cordially congratulate you on your first great work. You will find, I should think, that Wallace will fully appreciate it." ("Life and Letters", II. pages 391-393.) Four days later, Nov. 24, Darwin wrote to Hooker on the same subject: "I have now finished his paper...' it seems to me admirable. To my mind the act of segregation of varieties into species was never so plainly brought forward, and there are heaps of capital miscellaneous observations." ("More Letters", I. page 214.) Darwin was here referring to the tendency of similar varieties of the same species to pair together, and on Nov. 25 he wrote to Bates asking for fuller information on this subject. ("More Letters", I. page 215. See also parts of Darwin's letter to Bates in "Life and Letters", II. page 392.) If Bates's opinion were well founded, sexual selection would bear a most important part in the establishment of such species. (See Poulton, "Essays on Evolution", 1908, pages 65, 85-88.) It must be admitted, however, that the evidence is as yet quite insufficient to establish this conclusion. It is interesting to observe how Darwin at once fixed on the part of Bates's memoir which seemed to bear upon sexual selection. A review of Bates's theory of Mimicry was contributed by Darwin to the "Natural History Review" (New Ser. Vol. III. 1863, page 219.) and an account of it is to be found in the "Origin" (Edition 1872, pages 375-378.) and in "The Descent of Man". (Edition 1874, pages 323-325.) Darwin continually writes of the value of hypothesis as the inspiration of inquiry. We find an example in his letter to Bates, Nov. 22, 1860: "I have an old belief that a good observer really means a good theorist, and I fully expect to find your observations most valuable." ("More Letters", I. page 176.) Darwin's letter refers to many problems upon which Bates had theorised and observed, but as regards Mimicry itself the hypothesis was thought out after the return of the letter from the Amazons, when he no longer had the opportunity of testing it by the observation of living Nature. It is by no means improbable that, had he been able to apply this test, Bates would have recognised that his division of butterfly resemblances into two classes,--one due to the theory of mimicry, the other to the influence of local conditions,--could not be sustained. Fritz Muller's contributions to the problem of Mimicry were all made in S.E. Brazil, and numbers of them were communicated, with other observations on natural history, to Darwin, and by him sent to Professor R. Meldola who published many of the facts. Darwin's letters to Meldola (Poulton, "Charles Darwin and the theory of Natural Selection", London, 1896, pages 199-218.) contain abundant proofs of his interest in Muller's work upon Mimicry. One deeply interesting letter (Loc. cit. pages 201, 202.) dated Jan. 23, 1872, proves that Fritz Muller before he originated the theory of Common Warning Colours (Synaposematic Resemblance or Mullerian Mimicry), which will ever be associated with his name, had conceived the idea of the production of mimetic likeness by sexual selection. Darwin's letter to Meldola shows that he was by no means inclined to dismiss the suggestion as worthless, although he considered it daring. "You will also see in this letter a strange speculation, which I should not dare to publish, about the appreciation of certain colours being developed in those species which frequently behold other forms similarly ornamented. I do not feel at all sure that this view is as incredible as it may at first appear. Similar ideas have passed through my mind when considering the dull colours of all the organisms which inhabit dull-coloured regions, such as Patagonia and the Galapagos Is." A little later, on April 5, he wrote to Professor August Weismann on the same subject: "It may be suspected that even the habit of viewing differently coloured surrounding objects would influence their taste, and Fritz Muller even goes so far as to believe that the sight of gaudy butterflies might influence the taste of distinct species." ("Life and Letters", III. page 157.) This remarkable suggestion affords interesting evidence that F. Muller was not satisfied with the sufficiency of Bates's theory. Nor is this surprising when we think of the numbers of abundant conspicuous butterflies which he saw exhibiting mimetic likenesses. The common instances in his locality, and indeed everywhere in tropical America, were anything but the hard-pressed struggling forms assumed by the theory of Bates. They belonged to the groups which were themselves mimicked by other butterflies. Fritz Muller's suggestion also shows that he did not accept Bates's alternative explanation of a superficial likeness between models themselves, based on some unknown influence of local physico-chemical forces. At the same time Muller's own suggestion was subject to this apparently fatal objection, that the sexual selection he invoked would tend to produce resemblances in the males rather than the females, while it is well known that when the sexes differ the females are almost invariably more perfectly mimetic than the males and in a high proportion of cases are mimetic while the males are non-mimetic. The difficulty was met several years later by Fritz Muller's well-known theory, published in 1879 ("Kosmos", May 1879, page 100.), and immediately translated by Meldola and brought before the Entomological Society. ("Proc. Ent. Soc. Lond." 1879, page xx.) Darwin's letter to Meldola dated June 6, 1879, shows "that the first introduction of this new and most suggestive hypothesis into this country was due to the direct influence of Darwin himself, who brought it before the notice of the one man who was likely to appreciate it at its true value and to find the means for its presentation to English naturalists." ("Charles Darwin and the Theory of Natural Selection", page 214.) Of the hypothesis itself Darwin wrote "F. Muller's view of the mutual protection was quite new to me." (Ibid. page 213.) The hypothesis of Mullerian mimicry was at first strongly opposed. Bates himself could never make up his mind to accept it. As the Fellows were walking out of the meeting at which Professor Meldola explained the hypothesis, an eminent entomologist, now deceased, was heard to say to Bates: "It's a case of save me from my friends!" The new ideas encountered and still encounter to a great extent the difficulty that the theory of Bates had so completely penetrated the literature of natural history. The present writer has observed that naturalists who have not thoroughly absorbed the older hypothesis are usually far more impressed by the newer one than are those whose allegiance has already been rendered. The acceptance of Natural Selection itself was at first hindered by similar causes, as Darwin clearly recognised: "If you argue about the non-acceptance of Natural Selection, it seems to me a very striking fact that the Newtonian theory of gravitation, which seems to every one now so certain and plain, was rejected by a man so extraordinarily able as Leibnitz. The truth will not penetrate a preoccupied mind." (To Sir J. Hooker, July 28, 1868, "More Letters", I. page 305. See also the letter to A.R. Wallace, April 30, 1868, in "More Letters" II. page 77, lines 6-8 from top.) There are many naturalists, especially students of insects, who appear to entertain an inveterate hostility to any theory of mimicry. Some of them are eager investigators in the fascinating field of geographical distribution, so essential for the study of Mimicry itself. The changes of pattern undergone by a species of Erebia as we follow it over different parts of the mountain ranges of Europe is indeed a most interesting inquiry, but not more so than the differences between e.g. the Acraea johnstoni of S.E. Rhodesia and of Kilimanjaro. A naturalist who is interested by the Erebia should be equally interested by the Acraea; and so he would be if the student of mimicry did not also record that the characteristics which distinguish the northern from the southern individuals of the African species correspond with the presence, in the north but not in the south, of certain entirely different butterflies. That this additional information should so greatly weaken, in certain minds, the appeal of a favourite study, is a psychological problem of no little interest. This curious antagonism is I believe confined to a few students of insects. Those naturalists who, standing rather farther off, are able to see the bearings of the subject more clearly, will usually admit the general support yielded by an ever-growing mass of observations to the theories of Mimicry propounded by H.W. Bates and Fritz Muller. In like manner natural selection itself was in the early days often best understood and most readily accepted by those who were not naturalists. Thus Darwin wrote to D.T. Ansted, Oct. 27, 1860: "I am often in despair in making the generality of NATURALISTS even comprehend me. Intelligent men who are not naturalists and have not a bigoted idea of the term species, show more clearness of mind." ("More Letters", I. page 175.) Even before the "Origin" appeared Darwin anticipated the first results upon the mind of naturalists. He wrote to Asa Gray, Dec. 21, 1859: "I have made up my mind to be well abused; but I think it of importance that my notions should be read by intelligent men, accustomed to scientific argument, though NOT naturalists. It may seem absurd, but I think such men will drag after them those naturalists who have too firmly fixed in their heads that a species is an entity." ("Life and Letters" II. page 245.) Mimicry was not only one of the first great departments of zoological knowledge to be studied under the inspiration of natural Selection, it is still and will always remain one of the most interesting and important of subjects in relation to this theory as well as to evolution. In mimicry we investigate the effect of environment in its simplest form: we trace the effects of the pattern of a single species upon that of another far removed from it in the scale of classification. When there is reason to believe that the model is an invader from another region and has only recently become an element in the environment of the species native to its second home, the problem gains a special interest and fascination. Although we are chiefly dealing with the fleeting and changeable element of colour we expect to find and we do find evidence of a comparatively rapid evolution. The invasion of a fresh model is for certain species an unusually sudden change in the forces of the environment and in some instances we have grounds for the belief that the mimetic response has not been long delayed. MIMICRY AND SEX. Ever since Wallace's classical memoir on mimicry in the Malayan Swallowtail butterflies, those naturalists who have written on the subject have followed his interpretation of the marked prevalence of mimetic resemblance in the female sex as compared with the male. They have believed with Wallace that the greater dangers of the female, with slower flight and often alighting for oviposition, have been in part met by the high development of this special mode of protection. The fact cannot be doubted. It is extremely common for a non-mimetic male to be accompanied by a beautifully mimetic female and often by two or three different forms of female, each mimicking a different model. The male of a polymorphic mimetic female is, in fact, usually non-mimetic (e.g. Papilio dardanus = merope), or if a mimic (e.g. the Nymphaline genus Euripus), resembles a very different model. On the other hand a non-mimetic female accompanied by a mimetic male is excessively rare. An example is afforded by the Oriental Nymphaline, Cethosia, in which the males of some species are rough mimics of the brown Danaines. In some of the orb-weaving spiders the males mimic ants, while the much larger females are non-mimetic. When both sexes mimic, it is very common in butterflies and is also known in moths, for the females to be better and often far better mimics than the males. Although still believing that Wallace's hypothesis in large part accounts for the facts briefly summarised above, the present writer has recently been led to doubt whether it offers a complete explanation. Mimicry in the male, even though less beneficial to the species than mimicry in the female, would still surely be advantageous. Why then is it so often entirely restricted to the female? While the attempt to find an answer to this question was haunting me, I re-read a letter written by Darwin to Wallace, April 15, 1868, containing the following sentences: "When female butterflies are more brilliant than their males you believe that they have in most cases, or in all cases, been rendered brilliant so as to mimic some other species, and thus escape danger. But can you account for the males not having been rendered equally brilliant and equally protected? Although it may be most for the welfare of the species that the female should be protected, yet it would be some advantage, certainly no disadvantage, for the unfortunate male to enjoy an equal immunity from danger. For my part, I should say that the female alone had happened to vary in the right manner, and that the beneficial variations had been transmitted to the same sex alone. Believing in this, I can see no improbability (but from analogy of domestic animals a strong probability) that variations leading to beauty must often have occurred in the males alone, and been transmitted to that sex alone. Thus I should account in many cases for the greater beauty of the male over the female, without the need of the protective principle." ("More Letters", II. pages 73, 74. On the same subject--"the gay-coloured females of Pieris" (Perrhybris (Mylothris) pyrrha of Brazil), Darwin wrote to Wallace, May 5, 1868, as follows: "I believe I quite follow you in believing that the colours are wholly due to mimicry; and I further believe that the male is not brilliant from not having received through inheritance colour from the female, and from not himself having varied; in short, that he has not been influenced by selection." It should be noted that the male of this species does exhibit a mimetic pattern on the under surface. "More Letters" II. page 78.) The consideration of the facts of mimicry thus led Darwin to the conclusion that the female happens to vary in the right manner more commonly than the male, while the secondary sexual characters of males supported the conviction "that from some unknown cause such characters (viz. new characters arising in one sex and transmitted to it alone) apparently appear oftener in the male than in the female." (Letter from Darwin to Wallace, May 5, 1867, "More Letters", II. Page 61.) Comparing these conflicting arguments we are led to believe that the first is the stronger. Mimicry in the male would be no disadvantage but an advantage, and when it appears would be and is taken advantage of by selection. The secondary sexual characters of males would be no advantage but a disadvantage to females, and, as Wallace thinks, are withheld from this sex by selection. It is indeed possible that mimicry has been hindered and often prevented from passing to the males by sexual selection. We know that Darwin was much impressed ("Descent of Man", page 325.) by Thomas Belt's daring and brilliant suggestion that the white patches which exist, although ordinarily concealed, on the wings of mimetic males of certain Pierinae (Dismorphia), have been preserved by preferential mating. He supposed this result to have been brought about by the females exhibiting a deep-seated preference for males that displayed the chief ancestral colour, inherited from periods before any mimetic pattern had been evolved in the species. But it has always appeared to me that Belt's deeply interesting suggestion requires much solid evidence and repeated confirmation before it can be accepted as a valid interpretation of the facts. In the present state of our knowledge, at any rate of insects and especially of Lepidoptera, it is probable that the female is more apt to vary than the male and that an important element in the interpretation of prevalent female mimicry is provided by this fact. In order adequately to discuss the question of mimicry and sex it would be necessary to analyse the whole of the facts, so far as they are known in butterflies. On the present occasion it is only possible to state the inferences which have been drawn from general impressions,--inferences which it is believed will be sustained by future inquiry. (1) Mimicry may occasionally arise in one sex because the differences which distinguish it from the other sex happen to be such as to afford a starting-point for the resemblance. Here the male is at no disadvantage as compared with the female, and the rarity of mimicry in the male alone (e.g. Cethosia) is evidence that the great predominance of female mimicry is not to be thus explained. (2) The tendency of the female to dimorphism and polymorphism has been of great importance in determining this predominance. Thus if the female appear in two different forms and the male in only one it will be twice as probable that she will happen to possess a sufficient foundation for the evolution of mimicry. (3) The appearance of melanic or partially melanic forms in the female has been of very great service, providing as it does a change of ground-colour. Thus the mimicry of the black generally red-marked American "Aristolochia swallowtails" (Pharmacophagus) by the females of Papilio swallowtails was probably begun in this way. (4) It is probably incorrect to assume with Haase that mimicry always arose in the female and was later acquired by the male. Both sexes of the third section of swallowtails (Cosmodesmus) mimic Pharmacophagus in America, far more perfectly than do the females of Papilio. But this is not due to Cosmodesmus presenting us with a later stage of history begun in Papilio; for in Africa Cosmodesmus is still mimetic (of Danainae) in both sexes although the resemblances attained are imperfect, while many African species of Papilio have non-mimetic males with beautifully mimetic females. The explanation is probably to be sought in the fact that the females of Papilio are more variable and more often tend to become dimorphic than those of Cosmodesmus, while the latter group has more often happened to possess a sufficient foundation for the origin of the resemblance in patterns which, from the start, were common to male and female. (5) In very variable species with sexes alike, mimicry can be rapidly evolved in both sexes out of very small beginnings. Thus the reddish marks which are common in many individuals of Limenitis arthemis were almost certainly the starting-point for the evolution of the beautifully mimetic L. archippus. Nevertheless in such cases, although there is no reason to suspect any greater variability, the female is commonly a somewhat better mimic than the male and often a very much better mimic. Wallace's principle seems here to supply the obvious interpretation. (6) When the difference between the patterns of the model and presumed ancestor of the mimic is very great, the female is often alone mimetic; when the difference is comparatively small, both sexes are commonly mimetic. The Nymphaline genus Hypolimnas is a good example. In Hypolimnas itself the females mimic Danainae with patterns very different from those preserved by the non-mimetic males: in the sub-genus Euralia, both sexes resemble the black and white Ethiopian Danaines with patterns not very dissimilar from that which we infer to have existed in the non-mimetic ancestor. (7) Although a melanic form or other large variation may be of the utmost importance in facilitating the start of a mimetic likeness, it is impossible to explain the evolution of any detailed resemblance in this manner. And even the large colour variation itself may well be the expression of a minute and "continuous" change in the chemical and physical constitution of pigments. SEXUAL SELECTION (EPIGAMIC CHARACTERS). We do not know the date at which the idea of Sexual Selection arose in Darwin's mind, but it was probably not many years after the sudden flash of insight which, in October 1838, gave to him the theory of Natural Selection. An excellent account of Sexual Selection occupies the concluding paragraph of Part I. of Darwin's Section of the Joint Essay on Natural Selection, read July 1st, 1858, before the Linnean Society. ("Journ. Proc. Linn. Soc." Vol. III. 1859, page 50.) The principles are so clearly and sufficiently stated in these brief sentences that it is appropriate to quote the whole: "Besides this natural means of selection, by which those individuals are preserved, whether in their egg, or larval, or mature state, which are best adapted to the place they fill in nature, there is a second agency at work in most unisexual animals, tending to produce the same effect, namely, the struggle of the males for the females. These struggles are generally decided by the law of battle, but in the case of birds, apparently, by the charms of their song, by their beauty or their power of courtship, as in the dancing rock-thrush of Guiana. The most vigorous and healthy males, implying perfect adaptation, must generally gain the victory in their contests. This kind of selection, however, is less rigorous than the other; it does not require the death of the less successful, but gives to them fewer descendants. The struggle falls, moreover, at a time of year when food is generally abundant, and perhaps the effect chiefly produced would be the modification of the secondary sexual characters, which are not related to the power of obtaining food, or to defence from enemies, but to fighting with or rivalling other males. The result of this struggle amongst the males may be compared in some respects to that produced by those agriculturists who pay less attention to the careful selection of all their young animals, and more to the occasional use of a choice mate." A full exposition of Sexual Selection appeared in the "The Descent of Man" in 1871, and in the greatly augmented second edition, in 1874. It has been remarked that the two subjects, "The Descent of Man and Selection in Relation to Sex", seem to fuse somewhat imperfectly into the single work of which they form the title. The reason for their association is clearly shown in a letter to Wallace, dated May 28, 1864: "... I suspect that a sort of sexual selection has been the most powerful means of changing the races of man." ("More Letters", II. page 33.) Darwin, as we know from his Autobiography ("Life and Letters", I. page 94.), was always greatly interested in this hypothesis, and it has been shown in the preceding pages that he was inclined to look favourably upon it as an interpretation of many appearances usually explained by Natural Selection. Hence Sexual Selection, incidentally discussed in other sections of the present essay, need not be considered at any length, in the section specially allotted to it. Although so interested in the subject and notwithstanding his conviction that the hypothesis was sound, Darwin was quite aware that it was probably the most vulnerable part of the "Origin". Thus he wrote to H.W. Bates, April 4, 1861: "If I had to cut up myself in a review I would have (worried?) and quizzed sexual selection; therefore, though I am fully convinced that it is largely true, you may imagine how pleased I am at what you say on your belief." ("More Letters", I. page 183.) The existence of sound-producing organs in the males of insects was, Darwin considered, the strongest evidence in favour of the operation of sexual selection in this group. ("Life and Letters", III. pages 94, 138.) Such a conclusion has received strong support in recent years by the numerous careful observations of Dr F.A. Dixey ("Proc. Ent. Soc. Lond." 1904, page lvi; 1905, pages xxxvii, liv; 1906, page ii.) and Dr G.B. Longstaff ("Proc. Ent. Soc. Lond." 1905, page xxxv; "Trans. Ent. Soc. Lond." 1905, page 136; 1908, page 607.) on the scents of male butterflies. The experience of these naturalists abundantly confirms and extends the account given by Fritz Muller ("Jen. Zeit." Vol. XI. 1877, page 99; "Trans. Ent. Soc. Lond." 1878, page 211.) of the scents of certain Brazilian butterflies. It is a remarkable fact that the apparently epigamic scents of male butterflies should be pleasing to man while the apparently aposematic scents in both sexes of species with warning colours should be displeasing to him. But the former is far more surprising than the latter. It is not perhaps astonishing that a scent which is ex hypothesi unpleasant to an insect-eating Vertebrate should be displeasing to the human sense; but it is certainly wonderful that an odour which is ex hypothesi agreeable to a female butterfly should also be agreeable to man. Entirely new light upon the seasonal appearance of epigamic characters is shed by the recent researches of C.W. Beebe ("The American Naturalist", Vol. XLII. No. 493, Jan. 1908, page 34.), who caused the scarlet tanager (Piranga erythromelas) and the bobolink (Dolichonyx oryzivorus) to retain their breeding plumage through the whole year by means of fattening food, dim illumination, and reduced activity. Gradual restoration to the light and the addition of meal-worms to the diet invariably brought back the spring song, even in the middle of winter. A sudden alteration of temperature, either higher or lower, caused the birds nearly to stop feeding, and one tanager lost weight rapidly and in two weeks moulted into the olive-green winter plumage. After a year, and at the beginning of the normal breeding season, "individual tanagers and bobolinks were gradually brought under normal conditions and activities," and in every case moulted from nuptial plumage to nuptial plumage. "The dull colours of the winter season had been skipped." The author justly claims to have established "that the sequence of plumage in these birds is not in any way predestined through inheritance..., but that it may be interrupted by certain factors in the environmental complex." XVI. GEOGRAPHICAL DISTRIBUTION OF PLANTS. By Sir William Thiselton-Dyer, K.C.M.G., C.I.E. Sc.D., F.R.S. The publication of "The Origin of Species" placed the study of Botanical Geography on an entirely new basis. It is only necessary to study the monumental "Geographie Botanique raisonnee" of Alphonse De Candolle, published four years earlier (1855), to realise how profound and far-reaching was the change. After a masterly and exhaustive discussion of all available data De Candolle in his final conclusions could only arrive at a deadlock. It is sufficient to quote a few sentences:-- "L'opinion de Lamarck est aujourd'hui abandonee par tous les naturalistes qui ont etudie sagement les modifications possibles des etres organises... "Et si l'on s'ecarte des exagerations de Lamarck, si l'on suppose un premier type de chaque genre, de chaque famille tout au moins, on se trouve encore a l'egard de l'origine de ces types en presence de la grande question de la creation. "Le seul parti a prendre est donc d'envisager les etres organises comme existant depuis certaines epoques, avec leurs qualites particulieres." (Vol. II. page 1107.) Reviewing the position fourteen years afterwards, Bentham remarked:--"These views, generally received by the great majority of naturalists at the time De Candolle wrote, and still maintained by a few, must, if adhered to, check all further enquiry into any connection of facts with causes," and he added, "there is little doubt but that if De Candolle were to revise his work, he would follow the example of so many other eminent naturalists, and... insist that the present geographical distribution of plants was in most instances a derivative one, altered from a very different former distribution." ("Pres. Addr." (1869) "Proc. Linn. Soc." 1868-69, page lxviii.) Writing to Asa Gray in 1856, Darwin gave a brief preliminary account of his ideas as to the origin of species, and said that geographical distribution must be one of the tests of their validity. ("Life and Letters", II. page 78.) What is of supreme interest is that it was also their starting-point. He tells us:--"When I visited, during the voyage of H.M.S. "Beagle", the Galapagos Archipelago,... I fancied myself brought near to the very act of creation. I often asked myself how these many peculiar animals and plants had been produced: the simplest answer seemed to be that the inhabitants of the several islands had descended from each other, undergoing modification in the course of their descent." ("The Variation of Animals and Plants" (2nd edition), 1890, I. pages 9, 10.) We need not be surprised then, that in writing in 1845 to Sir Joseph Hooker, he speaks of "that grand subject, that almost keystone of the laws of creation, Geographical Distribution." ("Life and Letters", I. page 336.) Yet De Candolle was, as Bentham saw, unconsciously feeling his way, like Lyell, towards evolution, without being able to grasp it. They both strove to explain phenomena by means of agencies which they saw actually at work. If De Candolle gave up the ultimate problem as insoluble:--"La creation ou premiere formation des etres organises echappe, par sa nature et par son anciennete, a nos moyens d'observation" (Loc. cit. page 1106.), he steadily endeavoured to minimise its scope. At least half of his great work is devoted to the researches by which he extricated himself from a belief in species having had a multiple origin, the view which had been held by successive naturalists from Gmelin to Agassiz. To account for the obvious fact that species constantly occupy dissevered areas, De Candolle made a minute study of their means of transport. This was found to dispose of the vast majority of cases, and the remainder he accounted for by geographical change. (Loc. cit. page 1116.) But Darwin strenuously objected to invoking geographical change as a solution of every difficulty. He had apparently long satisfied himself as to the "permanence of continents and great oceans." Dana, he tells us "was, I believe, the first man who maintained" this ("Life and Letters", III. page 247. Dana says:--"The continents and oceans had their general outline or form defined in earliest time," "Manual of Geology", revised edition. Philadelphia, 1869, page 732. I have no access to an earlier edition.), but he had himself probably arrived at it independently. Modern physical research tends to confirm it. The earth's centre of gravity, as pointed out by Pratt from the existence of the Pacific Ocean, does not coincide with its centre of figure, and it has been conjectured that the Pacific Ocean dates its origin from the separation of the moon from the earth. The conjecture appears to be unnecessary. Love shows that "the force that keeps the Pacific Ocean on one side of the earth is gravity, directed more towards the centre of gravity than the centre of the figure." ("Report of the 77th Meeting of the British Association" (Leicester, 1907), London, 1908, page 431.) I can only summarise the conclusions of a technical but masterly discussion. "The broad general features of the distribution of continent and ocean can be regarded as the consequences of simple causes of a dynamical character," and finally, "As regards the contour of the great ocean basins, we seem to be justified in saying that the earth is approximately an oblate spheroid, but more nearly an ellipsoid with three unequal axes, having its surface furrowed according to the formula for a certain spherical harmonic of the third degree" (Ibid. page 436.), and he shows that this furrowed surface must be produced "if the density is greater in one hemispheroid than in the other, so that the position of the centre of gravity is eccentric." (Ibid. page 431.) Such a modelling of the earth's surface can only be referred to a primitive period of plasticity. If the furrows account for the great ocean basins, the disposition of the continents seems equally to follow. Sir George Darwin has pointed out that they necessarily "arise from a supposed primitive viscosity or plasticity of the earth's mass. For during this course of evolution the earth's mass must have suffered a screwing motion, so that the polar regions have travelled a little from west to east relatively to the equator. This affords a possible explanation of the north and south trend of our great continents." ("Encycl. Brit." (9th edition), Vol. XXIII. "Tides", page 379.) It would be trespassing on the province of the geologist to pursue the subject at any length. But as Wallace ("Island Life" (2nd edition), 1895, page 103.), who has admirably vindicated Darwin's position, points out, the "question of the permanence of our continents... lies at the root of all our inquiries into the great changes of the earth and its inhabitants." But he proceeds: "The very same evidence which has been adduced to prove the GENERAL stability and permanence of our continental areas also goes to prove that they have been subjected to wonderful and repeated changes in DETAIL." (Loc. cit. page 101.) Darwin of course would have admitted this, for with a happy expression he insisted to Lyell (1856) that "the skeletons, at least, of our continents are ancient." ("More Letters", II. page 135.) It is impossible not to admire the courage and tenacity with which he carried on the conflict single-handed. But he failed to convince Lyell. For we still find him maintaining in the last edition of the "Principles": "Continents therefore, although permanent for whole geological epochs, shift their positions entirely in the course of ages." (Lyell's "Principles of Geology" (11th edition), London, 1872, I. page 258.) Evidence, however, steadily accumulates in Darwin's support. His position still remains inexpugnable that it is not permissible to invoke geographical change to explain difficulties in distribution without valid geological and physical support. Writing to Mellard Reade, who in 1878 had said, "While believing that the ocean-depths are of enormous age, it is impossible to reject other evidences that they have once been land," he pointed out "the statement from the 'Challenger' that all sediment is deposited within one or two hundred miles from the shores." ("More Letters", II. page 146.) The following year Sir Archibald Geikie ("Geographical Evolution", "Proc. R. Geogr. Soc." 1879, page 427.) informed the Royal Geographical Society that "No part of the results obtained by the 'Challenger' expedition has a profounder interest for geologists and geographers than the proof which they furnish that the floor of the ocean basins has no real analogy among the sedimentary formations which form most of the framework of the land." Nor has Darwin's earlier argument ever been upset. "The fact which I pointed out many years ago, that all oceanic islands are volcanic (except St Paul's, and now that is viewed by some as the nucleus of an ancient volcano), seem to me a strong argument that no continent ever occupied the great oceans." ("More Letters", II. page 146.) Dr Guppy, who devoted several years to geological and botanical investigations in the Pacific, found himself forced to similar conclusions. "It may be at once observed," he says, "that my belief in the general principle that islands have always been islands has not been shaken," and he entirely rejects "the hypothesis of a Pacific continent." He comes back, in full view of the problems on the spot, to the position from which, as has been seen, Darwin started: "If the distribution of a particular group of plants or animals does not seem to accord with the present arrangement of the land, it is by far the safest plan, even after exhausting all likely modes of explanation, not to invoke the intervention of geographical changes; and I scarcely think that our knowledge of any one group of organisms is ever sufficiently precise to justify a recourse to hypothetical alterations in the present relations of land and sea." ("Observations of a Naturalist in the Pacific between 1896 and 1899", London, 1903, I. page 380.) Wallace clinches the matter when he finds "almost the whole of the vast areas of the Atlantic, Pacific, Indian, and Southern Oceans, without a solitary relic of the great islands or continents supposed to have sunk beneath their waves." ("Island Life", page 105.) Writing to Wallace (1876), Darwin warmly approves the former's "protest against sinking imaginary continents in a quite reckless manner, as was stated by Forbes, followed, alas, by Hooker, and caricatured by Wollaston and (Andrew) Murray." ("Life and Letters", III. page 230.) The transport question thus became of enormously enhanced importance. We need not be surprised then at his writing to Lyell in 1856:--"I cannot avoid thinking that Forbes's 'Atlantis' was an ill-service to science, as checking a close study of means of dissemination" (Ibid. II. page 78.), and Darwin spared no pains to extend our knowledge of them. He implores Hooker, ten years later, to "admit how little is known on the subject," and summarises with some satisfaction what he had himself achieved:--"Remember how recently you and others thought that salt water would soon kill seeds... Remember that no one knew that seeds would remain for many hours in the crops of birds and retain their vitality; that fish eat seeds, and that when the fish are devoured by birds the seeds can germinate, etc. Remember that every year many birds are blown to Madeira and to the Bermudas. Remember that dust is blown 1000 miles across the Atlantic." ("More Letters", I. page 483.) It has always been the fashion to minimise Darwin's conclusions, and these have not escaped objection. The advocatus diaboli has a useful function in science. But in attacking Darwin his brief is generally found to be founded on a slender basis of facts. Thus Winge and Knud Andersen have examined many thousands of migratory birds and found "that their crops and stomachs were always empty. They never observed any seeds adhering to the feathers, beaks or feet of the birds." (R.F. Scharff, "European Animals", page 64, London, 1907.) The most considerable investigation of the problem of Plant Dispersal since Darwin is that of Guppy. He gives a striking illustration of how easily an observer may be led into error by relying on negative evidence. "When Ekstam published, in 1895, the results of his observations on the plants of Nova Zembla, he observed that he possessed no data to show whether swimming and wading birds fed on berries; and he attached all importance to dispersal by winds. On subsequently visiting Spitzbergen he must have been at first inclined, therefore, to the opinion of Nathorst, who, having found only a solitary species of bird (a snow-sparrow) in that region, naturally concluded that birds had been of no importance as agents in the plant-stocking. However, Ekstam's opportunities were greater, and he tells us that in the craws of six specimens of Lagopus hyperboreus shot in Spitzbergen in August he found represented almost 25 per cent. of the usual phanerogamic flora of that region in the form of fruits, seeds, bulbils, flower-buds, leaf-buds, etc... " "The result of Ekstam's observations in Spitzbergen was to lead him to attach a very considerable importance in plant dispersal to the agency of birds; and when in explanation of the Scandinavian elements in the Spitzbergen flora he had to choose between a former land connection and the agency of birds, he preferred the bird." (Guppy, op. cit. II. pages 511, 512.) Darwin objected to "continental extensions" on geological grounds, but he also objected to Lyell that they do not "account for all the phenomena of distribution on islands" ("Life and Letters", II. page 77.), such for example as the absence of Acacias and Banksias in New Zealand. He agreed with De Candolle that "it is poor work putting together the merely POSSIBLE means of distribution." But he also agreed with him that they were the only practicable door of escape from multiple origins. If they would not work then "every one who believes in single centres will have to admit continental extensions" (Ibid. II. page 82.), and that he regarded as a mere counsel of despair:--"to make continents, as easily as a cook does pancakes." (Ibid. II. page 74.) The question of multiple origins however presented itself in another shape where the solution was much more difficult. The problem, as stated by Darwin, is this:--"The identity of many plants and animals, on mountain-summits, separated from each other by hundreds of miles of lowlands... without the apparent possibility of their having migrated from one point to the other." He continues, "even as long ago as 1747, such facts led Gmelin to conclude that the same species must have been independently created at several distinct points; and we might have remained in this same belief, had not Agassiz and others called vivid attention to the Glacial period, which affords... a simple explanation of the facts." ("Origin of Species" (6th edition) page 330.) The "simple explanation" was substantially given by E. Forbes in 1846. It is scarcely too much to say that it belongs to the same class of fertile and far-reaching ideas as "natural selection" itself. It is an extraordinary instance, if one were wanted at all, of Darwin's magnanimity and intense modesty that though he had arrived at the theory himself, he acquiesced in Forbes receiving the well-merited credit. "I have never," he says, "of course alluded in print to my having independently worked out this view." But he would have been more than human if he had not added:--"I was forestalled in... one important point, which my vanity has always made me regret." ("Life and Letters", I. page 88.) Darwin, however, by applying the theory to trans-tropical migration, went far beyond Forbes. The first enunciation to this is apparently contained in a letter to Asa Gray in 1858. The whole is too long to quote, but the pith is contained in one paragraph. "There is a considerable body of geological evidence that during the Glacial epoch the whole world was colder; I inferred that,... from erratic boulder phenomena carefully observed by me on both the east and west coast of South America. Now I am so bold as to believe that at the height of the Glacial epoch, AND WHEN ALL TROPICAL PRODUCTIONS MUST HAVE BEEN CONSIDERABLY DISTRESSED, several temperate forms slowly travelled into the heart of the Tropics, and even reached the southern hemisphere; and some few southern forms penetrated in a reverse direction northward." ("Life and Letters", II. page 136.) Here again it is clear that though he credits Agassiz with having called vivid attention to the Glacial period, he had himself much earlier grasped the idea of periods of refrigeration. Putting aside the fact, which has only been made known to us since Darwin's death, that he had anticipated Forbes, it is clear that he gave the theory a generality of which the latter had no conception. This is pointed out by Hooker in his classical paper "On the Distribution of Arctic Plants" (1860). "The theory of a southern migration of northern types being due to the cold epochs preceding and during the glacial, originated, I believe, with the late Edward Forbes; the extended one, of the trans-tropical migration, is Mr Darwin's." ("Linn. Trans." XXIII. page 253. The attempt appears to have been made to claim for Heer priority in what I may term for short the arctic-alpine theory (Scharff, "European Animals", page 128). I find no suggestion of his having hit upon it in his correspondence with Darwin or Hooker. Nor am I aware of any reference to his having done so in his later publications. I am indebted to his biographer, Professor Schroter, of Zurich, for an examination of his earlier papers with an equally negative result.) Assuming that local races have derived from a common ancestor, Hooker's great paper placed the fact of the migration on an impregnable basis. And, as he pointed out, Darwin has shown that "such an explanation meets the difficulty of accounting for the restriction of so many American and Asiatic arctic types to their own peculiar longitudinal zones, and for what is a far greater difficulty, the representation of the same arctic genera by most closely allied species in different longitudes." The facts of botanical geography were vital to Darwin's argument. He had to show that they admitted of explanation without assuming multiple origins for species, which would be fatal to the theory of Descent. He had therefore to strengthen and extend De Candolle's work as to means of transport. He refused to supplement them by hypothetical geographical changes for which there was no independent evidence: this was simply to attempt to explain ignotum per ignotius. He found a real and, as it has turned out, a far-reaching solution in climatic change due to cosmical causes which compelled the migration of species as a condition of their existence. The logical force of the argument consists in dispensing with any violent assumption, and in showing that the principle of descent is adequate to explain the ascertained facts. It does not, I think, detract from the merit of Darwin's conclusions that the tendency of modern research has been to show that the effects of the Glacial period were less simple, more localised and less general than he perhaps supposed. He admitted that "equatorial refrigeration... must have been small." ("More Letters", I. page 177.) It may prove possible to dispense with it altogether. One cannot but regret that as he wrote to Bates:--"the sketch in the 'Origin' gives a very meagre account of my fuller MS. essay on this subject." (Loc. cit.) Wallace fully accepted "the effect of the Glacial epoch in bringing about the present distribution of Alpine and Arctic plants in the NORTHERN HEMISPHERE," but rejected "the lowering of the temperature of the tropical regions during the Glacial period" in order to account for their presence in the SOUTHERN hemisphere. ("More Letters", II. page 25 (footnote 1).) The divergence however does not lie very deep. Wallace attaches more importance to ordinary means of transport. "If plants can pass in considerable numbers and variety over wide seas and oceans, it must be yet more easy for them to traverse continuous areas of land, wherever mountain-chains offer suitable stations." ("Island Life" (2nd edition), London, 1895, page 512.) And he argues that such periodical changes of climate, of which the Glacial period may be taken as a type, would facilitate if not stimulate the process. (Loc. cit. page 518.) It is interesting to remark that Darwin drew from the facts of plant distribution one of his most ingenious arguments in support of this theory. (See "More Letters", I. page 424.) He tells us, "I was led to anticipate that the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera." ("Origin", page 44.) He argues "where, if we may use the expression, the manufactory of species has been active, we ought generally to find the manufactory still in action." (Ibid. page 45.) This proved to be the case. But the labour imposed upon him in the study was immense. He tabulated local floras "belting the whole northern hemisphere" ("More Letters", I. page 107.), besides voluminous works such as De Candolle's "Prodromus". The results scarcely fill a couple of pages. This is a good illustration of the enormous pains which he took to base any statement on a secure foundation of evidence, and for this the world, till the publication of his letters, could not do him justice. He was a great admirer of Herbert Spencer, whose "prodigality of original thought" astonished him. "But," he says, "the reflection constantly recurred to me that each suggestion, to be of real value to service, would require years of work." (Ibid. II. page 235.) At last the ground was cleared and we are led to the final conclusion. "If the difficulties be not insuperable in admitting that in the long course of time all the individuals of the same species belonging to the same genus, have proceeded from some one source; then all the grand leading facts of geographical distribution are explicable on the theory of migration, together with subsequent modification and the multiplication of new forms." ("Origin", page 360.) In this single sentence Darwin has stated a theory which, as his son F. Darwin has said with justice, has "revolutionized botanical geography." ("The Botanical Work of Darwin", "Ann. Bot." 1899, page xi.) It explains how physical barriers separate and form botanical regions; how allied species become concentrated in the same areas; how, under similar physical conditions, plants may be essentially dissimilar, showing that descent and not the surroundings is the controlling factor; how insular floras have acquired their peculiarities; in short how the most various and apparently uncorrelated problems fall easily and inevitably into line. The argument from plant distribution was in fact irresistible. A proof, if one were wanted, was the immediate conversion of what Hooker called "the stern keen intellect" ("More Letters", I. page 134.) of Bentham, by general consent the leading botanical systematist at the time. It is a striking historical fact that a paper of his own had been set down for reading at the Linnean Society on the same day as Darwin's, but had to give way. In this he advocated the fixity of species. He withdrew it after hearing Darwin's. We can hardly realise now the momentous effect on the scientific thought of the day of the announcement of the new theory. Years afterwards (1882) Bentham, notwithstanding his habitual restraint, could not write of it without emotion. "I was forced, however reluctantly, to give up my long-cherished convictions, the results of much labour and study." The revelation came without preparation. Darwin, he wrote, "never made any communications to me in relation to his views and labours." But, he adds, "I... fully adopted his theories and conclusions, notwithstanding the severe pain and disappointment they at first occasioned me." ("Life and Letters", II. page 294.) Scientific history can have few incidents more worthy. I do not know what is most striking in the story, the pathos or the moral dignity of Bentham's attitude. Darwin necessarily restricted himself in the "Origin" to establishing the general principles which would account for the facts of distribution, as a part of his larger argument, without attempting to illustrate them in particular cases. This he appears to have contemplated doing in a separate work. But writing to Hooker in 1868 he said:--"I shall to the day of my death keep up my full interest in Geographical Distribution, but I doubt whether I shall ever have strength to come in any fuller detail than in the "Origin" to this grand subject." ("More Letters", II. page 7.) This must be always a matter for regret. But we may gather some indication of his later speculations from the letters, the careful publication of which by F. Darwin has rendered a service to science, the value of which it is difficult to exaggerate. They admit us to the workshop, where we see a great theory, as it were, in the making. The later ideas that they contain were not it is true public property at the time. But they were communicated to the leading biologists of the day and indirectly have had a large influence. If Darwin laid the foundation, the present fabric of Botanical Geography must be credited to Hooker. It was a happy partnership. The far-seeing, generalising power of the one was supplied with data and checked in conclusions by the vast detailed knowledge of the other. It may be permitted to quote Darwin's generous acknowledgment when writing the "Origin":--"I never did pick any one's pocket, but whilst writing my present chapter I keep on feeling (even when differing most from you) just as if I were stealing from you, so much do I owe to your writings and conversation, so much more than mere acknowledgements show." ("Life and Letters", II. page 148 (footnote).) Fourteen years before he had written to Hooker: "I know I shall live to see you the first authority in Europe on... Geographical Distribution." (Ibid. I. page 336.) We owe it to Hooker that no one now undertakes the flora of a country without indicating the range of the species it contains. Bentham tells us: "After De Candolle, independently of the great works of Darwin... the first important addition to the science of geographical botany was that made by Hooker in his "Introductory Essay to the Flora of Tasmania", which, though contemporaneous only with the "Origin of Species", was drawn up with a general knowledge of his friend's observations and views." (Pres. Addr. (1869), "Proc. Linn. Soc." 1868-69, page lxxiv.) It cannot be doubted that this and the great memoir on the "Distribution of Arctic Plants" were only less epoch-making than the "Origin" itself, and must have supplied a powerful support to the general theory of organic evolution. Darwin always asserted his "entire ignorance of Botany." ("More Letters", I. page 400.) But this was only part of his constant half-humorous self-depreciation. He had been a pupil of Henslow, and it is evident that he had a good working knowledge of systematic botany. He could find his way about in the literature and always cites the names of plants with scrupulous accuracy. It was because he felt the want of such a work for his own researches that he urged the preparation of the "Index Kewensis", and undertook to defray the expense. It has been thought singular that he should have been elected a "correspondant" of the Academie des Sciences in the section of Botany, but it is not surprising that his work in Geographical Botany made the botanists anxious to claim him. His heart went with them. "It has always pleased me," he tells us, "to exalt plants in the scale of organised beings." ("Life and Letters", I. page 98.) And he declares that he finds "any proposition more easily tested in botanical works (Ibid. II. page 99.) than in zoological." In the "Introductory Essay" Hooker dwelt on the "continuous current of vegetation from Scandinavia to Tasmania" ("Introductory Essay to the Flora of Tasmania", London, 1859. Reprinted from the "Botany of the Antarctic Expedition", Part III., "Flora of Tasmania", Vol I. page ciii.), but finds little evidence of one in the reverse direction. "In the New World, Arctic, Scandinavian, and North American genera and species are continuously extended from the north to the south temperate and even Antarctic zones; but scarcely one Antarctic species, or even genus advances north beyond the Gulf of Mexico" (page civ.). Hooker considered that this negatived "the idea that the Southern and Northern Floras have had common origin within comparatively modern geological epochs." (Loc. cit.) This is no doubt a correct conclusion. But it is difficult to explain on Darwin's view alone, of alternating cold in the two hemispheres, the preponderant migration from the north to the south. He suggests, therefore, that it "is due to the greater extent of land in the north and to the northern forms... having... been advanced through natural selection and competition to a higher stage of perfection or dominating power." ("Origin of Species" (6th edition), page 340; cf. also "Life and Letters", II. page 142.) The present state of the Flora of New Zealand affords a striking illustration of the correctness of this view. It is poor in species, numbering only some 1400, of which three-fourths are endemic. They seem however quite unable to resist the invasion of new comers and already 600 species of foreign origin have succeeded in establishing themselves. If we accept the general configuration of the earth's surface as permanent a continuous and progressive dispersal of species from the centre to the circumference, i.e. southwards, seems inevitable. If an observer were placed above a point in St George's Channel from which one half of the globe was visible he would see the greatest possible quantity of land spread out in a sort of stellate figure. The maritime supremacy of the English race has perhaps flowed from the central position of its home. That such a disposition would facilitate a centrifugal migration of land organisms is at any rate obvious, and fluctuating conditions of climate operating from the pole would supply an effective means of propulsion. As these became more rigorous animals at any rate would move southwards to escape them. It would be equally the case with plants if no insuperable obstacle interposed. This implies a mobility in plants, notwithstanding what we know of means of transport which is at first sight paradoxical. Bentham has stated this in a striking way: "Fixed and immovable as is the individual plant, there is no class in which the race is endowed with greater facilities for the widest dispersion... Plants cast away their offspring in a dormant state, ready to be carried to any distance by those external agencies which we may deem fortuitous, but without which many a race might perish from the exhaustion of the limited spot of soil in which it is rooted." (Pres. Addr.(1869), "Proc. Linn. Soc." 1868-69, pages lxvi, lxvii.) I have quoted this passage from Bentham because it emphasises a point which Darwin for his purpose did not find it necessary to dwell upon, though he no doubt assumed it. Dispersal to a distance is, so to speak, an accidental incident in the life of a species. Lepidium Draba, a native of South-eastern Europe, owes its prevalence in the Isle of Thanet to the disastrous Walcheren expedition; the straw-stuffing of the mattresses of the fever-stricken soldiers who were landed there was used by a farmer for manure. Sir Joseph Hooker ("Royal Institution Lecture", April 12, 1878.) tells us that landing on Lord Auckland's Island, which was uninhabited, "the first evidence I met with of its having been previously visited by man was the English chickweed; and this I traced to a mound that marked the grave of a British sailor, and that was covered with the plant, doubtless the offspring of seed that had adhered to the spade or mattock with which the grave had been dug." Some migration from the spot where the individuals of a species have germinated is an essential provision against extinction. Their descendants otherwise would be liable to suppression by more vigorous competitors. But they would eventually be extinguished inevitably, as pointed out by Bentham, by the exhaustion of at any rate some one necessary constituent of the soil. Gilbert showed by actual analysis that the production of a "fairy ring" is simply due to the using up by the fungi of the available nitrogen in the enclosed area which continually enlarges as they seek a fresh supply on the outside margin. Anyone who cultivates a garden can easily verify the fact that every plant has some adaptation for varying degrees of seed-dispersal. It cannot be doubted that slow but persistent terrestrial migration has played an enormous part in bringing about existing plant-distribution, or that climatic changes would intensify the effect because they would force the abandonment of a former area and the occupation of a new one. We are compelled to admit that as an incident of the Glacial period a whole flora may have moved down and up a mountain side, while only some of its constituent species would be able to take advantage of means of long-distance transport. I have dwelt on the importance of what I may call short-distance dispersal as a necessary condition of plant life, because I think it suggests the solution of a difficulty which leads Guppy to a conclusion with which I am unable to agree. But the work which he has done taken as a whole appears to me so admirable that I do so with the utmost respect. He points out, as Bentham had already done, that long-distance dispersal is fortuitous. And being so it cannot have been provided for by previous adaptation. He says (Guppy, op. cit. II. page 99.): "It is not conceivable that an organism can be adapted to conditions outside its environment." To this we must agree; but, it may be asked, do the general means of plant dispersal violate so obvious a principle? He proceeds: "The great variety of the modes of dispersal of seeds is in itself an indication that the dispersing agencies avail themselves in a hap-hazard fashion of characters and capacities that have been developed in other connections." (Loc. cit. page 102.) "Their utility in these respects is an accident in the plant's life." (Loc. cit. page 100.) He attributes this utility to a "determining agency," an influence which constantly reappears in various shapes in the literature of Evolution and is ultra-scientific in the sense that it bars the way to the search for material causes. He goes so far as to doubt whether fleshy fruits are an adaptation for the dispersal of their contained seeds. (Loc. cit. page 102.) Writing as I am from a hillside which is covered by hawthorn bushes sown by birds, I confess I can feel little doubt on the subject myself. The essential fact which Guppy brings out is that long-distance unlike short-distance dispersal is not universal and purposeful, but selective and in that sense accidental. But it is not difficult to see how under favouring conditions one must merge into the other. Guppy has raised one novel point which can only be briefly referred to but which is of extreme interest. There are grounds for thinking that flowers and insects have mutually reacted upon one another in their evolution. Guppy suggests that something of the same kind may be true of birds. I must content myself with the quotation of a single sentence. "With the secular drying of the globe and the consequent differentiation of climate is to be connected the suspension to a great extent of the agency of birds as plant dispersers in later ages, not only in the Pacific Islands but all over the tropics. The changes of climate, birds and plants have gone on together, the range of the bird being controlled by the climate, and the distribution of the plant being largely dependent on the bird." (Loc.cit. II. page 221.) Darwin was clearly prepared to go further than Hooker in accounting for the southern flora by dispersion from the north. Thus he says: "We must, I suppose, admit that every yard of land has been successively covered with a beech-forest between the Caucasus and Japan." ("More Letters", II. page 9.) Hooker accounted for the dissevered condition of the southern flora by geographical change, but this Darwin could not admit. He suggested to Hooker that the Australian and Cape floras might have had a point of connection through Abyssinia (Ibid. I. page 447.), an idea which was promptly snuffed out. Similarly he remarked to Bentham (1869): "I suppose you think that the Restiaceae, Proteaceae, etc., etc. once extended over the whole world, leaving fragments in the south." (Ibid. I. page 380.) Eventually he conjectured "that there must have been a Tertiary Antarctic continent, from which various forms radiated to the southern extremities of our present continents." ("Life and Letters", III. page 231.) But characteristically he could not admit any land connections and trusted to "floating ice for transporting seed." ("More Letters", I. page 116.) I am far from saying that this theory is not deserving of serious attention, though there seems to be no positive evidence to support it, and it immediately raises the difficulty how did such a continent come to be stocked? We must, however, agree with Hooker that the common origin of the northern and southern floras must be referred to a remote past. That Darwin had this in his mind at the time of the publication of the "Origin" is clear from a letter to Hooker. "The view which I should have looked at as perhaps most probable (though it hardly differs from yours) is that the whole world during the Secondary ages was inhabited by marsupials, araucarias (Mem.--Fossil wood of this nature in South America), Banksia, etc.; and that these were supplanted and exterminated in the greater area of the north, but were left alive in the south." (Ibid. I. page 453.) Remembering that Araucaria, unlike Banksia, belongs to the earlier Jurassic not to the angiospermous flora, this view is a germinal idea of the widest generality. The extraordinary congestion in species of the peninsulas of the Old World points to the long-continued action of a migration southwards. Each is in fact a cul-de-sac into which they have poured and from which there is no escape. On the other hand the high degree of specialisation in the southern floras and the little power the species possess of holding their own in competition or in adaptation to new conditions point to long-continued isolation. "An island... will prevent free immigration and competition, hence a greater number of ancient forms will survive." (Ibid. I. page 481.) But variability is itself subject to variation. The nemesis of a high degree of protected specialisation is the loss of adaptability. (See Lyell, "The Geological Evidences of the Antiquity of Man", London, 1863, page 446.) It is probable that many elements of the southern flora are doomed: there is, for example, reason to think that the singular Stapelieae of S. Africa are a disappearing group. The tree Lobelias which linger in the mountains of Central Africa, in Tropical America and in the Sandwich Islands have the aspect of extreme antiquity. I may add a further striking illustration from Professor Seward: "The tall, graceful fronds of Matonia pectinata, forming miniature forests on the slopes of Mount Ophir and other districts in the Malay Peninsula in association with Dipteris conjugata and Dipteris lobbiana, represent a phase of Mesozoic life which survives 'Like a dim picture of the drowned past.'" ("Report of the 73rd Meeting of the British Assoc." (Southport, 1903), London, 1904, page 844.) The Matonineae are ferns with an unusually complex vascular system and were abundant "in the northern hemisphere during the earlier part of the Mesozoic era." It was fortunate for science that Wallace took up the task which his colleague had abandoned. Writing to him on the publication of his "Geographical Distribution of Animals" Darwin said: "I feel sure that you have laid a broad and safe foundation for all future work on Distribution. How interesting it will be to see hereafter plants treated in strict relation to your views." ("More Letters", II. page 12.) This hope was fulfilled in "Island Life". I may quote a passage from it which admirably summarises the contrast between the northern and the southern floras. "Instead of the enormous northern area, in which highly organised and dominant groups of plants have been developed gifted with great colonising and aggressive powers, we have in the south three comparatively small and detached areas, in which rich floras have been developed with SPECIAL adaptations to soil, climate, and organic environment, but comparatively impotent and inferior beyond their own domain." (Wallace, "Island Life", pages 527, 528.) It will be noticed that in the summary I have attempted to give of the history of the subject, efforts have been concentrated on bringing into relation the temperate floras of the northern and southern hemispheres, but no account has been taken of the rich tropical vegetation which belts the world and little to account for the original starting-point of existing vegetation generally. It must be remembered on the one hand that our detailed knowledge of the floras of the tropics is still very incomplete and far inferior to that of temperate regions; on the other hand palaeontological discoveries have put the problem in an entirely new light. Well might Darwin, writing to Heer in 1875, say: "Many as have been the wonderful discoveries in Geology during the last half-century, I think none have exceeded in interest your results with respect to the plants which formerly existed in the arctic regions." ("More Letters", II. page 240.) As early as 1848 Debey had described from the Upper Cretaceous rocks of Aix-la-Chapelle Flowering plants of as high a degree of development as those now existing. The fact was commented upon by Hooker ("Introd. Essay to the Flora of Tasmania", page xx.), but its full significance seems to have been scarcely appreciated. For it implied not merely that their evolution must have taken place but the foundations of existing distribution must have been laid in a preceding age. We now know from the discoveries of the last fifty years that the remains of the Neocomian flora occur over an area extending through 30 deg of latitude. The conclusion is irresistible that within this was its centre of distribution and probably of origin. Darwin was immensely impressed with the outburst on the world of a fully fledged angiospermous vegetation. He warmly approved the brilliant theory of Saporta that this happened "as soon (as) flower-frequenting insects were developed and favoured intercrossing." ("More Letters", II. page 21.) Writing to him in 1877 he says: "Your idea that dicotyledonous plants were not developed in force until sucking insects had been evolved seems to me a splendid one. I am surprised that the idea never occurred to me, but this is always the case when one first hears a new and simple explanation of some mysterious phenomenon." ("Life and Letters", III. page 285. Substantially the same idea had occurred earlier to F.W.A. Miquel. Remarking that "sucking insects (Haustellata)... perform in nature the important duty of maintaining the existence of the vegetable kingdom, at least as far as the higher orders are concerned," he points our that "the appearance in great numbers of haustellate insects occurs at and after the Cretaceous epoch, when the plants with pollen and closed carpels (Angiosperms) are found, and acquire little by little the preponderance in the vegetable kingdom." "Archives Neerlandaises", III. (1868). English translation in "Journ. of Bot." 1869, page 101.) Even with this help the abruptness still remains an almost insoluble problem, though a forecast of floral structure is now recognised in some Jurassic and Lower Cretaceous plants. But the gap between this and the structural complexity and diversity of angiosperms is enormous. Darwin thought that the evolution might have been accomplished during a period of prolonged isolation. Writing to Hooker (1881) he says: "Nothing is more extraordinary in the history of the Vegetable Kingdom, as it seems to me, than the APPARENTLY very sudden or abrupt development of the higher plants. I have sometimes speculated whether there did not exist somewhere during long ages an extremely isolated continent, perhaps near the South Pole." ("Life and Letters", III. page 248.) The present trend of evidence is, however, all in favour of a northern origin for flowering plants, and we can only appeal to the imperfection of the geological record as a last resource to extricate us from the difficulty of tracing the process. But Darwin's instinct that at some time or other the southern hemisphere had played an important part in the evolution of the vegetable kingdom did not mislead him. Nothing probably would have given him greater satisfaction than the masterly summary in which Seward has brought together the evidence for the origin of the Glossopteris flora in Gondwana land. "A vast continental area, of which remnants are preserved in Australia, South Africa and South America... A tract of enormous extent occupying an area, part of which has since given place to a southern ocean, while detached masses persist as portions of more modern continents, which have enabled us to read in their fossil plants and ice-scratched boulders the records of a lost continent, in which the Mesozoic vegetation of the northern continent had its birth." ("Encycl. Brit." (10th edition 1902), Vol. XXXI. ("Palaeobotany; Mesozoic"), page 422.) Darwin would probably have demurred on physical grounds to the extent of the continent, and preferred to account for the transoceanic distribution of its flora by the same means which must have accomplished it on land. It must in fairness be added that Guppy's later views give some support to the conjectural existence of the "lost continent." "The distribution of the genus Dammara" (Agathis) led him to modify his earlier conclusions. He tells us:--"In my volume on the geology of Vanua Levu it was shown that the Tertiary period was an age of submergence in the Western Pacific, and a disbelief in any previous continental condition was expressed. My later view is more in accordance with that of Wichmann, who, on geological grounds, contended that the islands of the Western Pacific were in a continental condition during the Palaeozoic and Mesozoic periods, and that their submergence and subsequent emergence took place in Tertiary times." (Guppy, op. cit. II. page 304.) The weight of the geological evidence I am unable to scrutinise. But though I must admit the possibility of some unconscious bias in my own mind on the subject, I am impressed with the fact that the known distribution of the Glossopteris flora in the southern hemisphere is precisely paralleled by that of Proteaceae and Restiaceae in it at the present time. It is not unreasonable to suppose that both phenomena, so similar, may admit of the same explanation. I confess it would not surprise me if fresh discoveries in the distribution of the Glossopteris flora were to point to the possibility of its also having migrated southwards from a centre of origin in the northern hemisphere. Darwin, however, remained sceptical "about the travelling of plants from the north EXCEPT DURING THE TERTIARY PERIOD." But he added, "such speculations seem to me hardly scientific, seeing how little we know of the old floras." ("Life and Letters", III. page 247.) That in later geological times the south has been the grave of the weakened offspring of the aggressive north can hardly be doubted. But if we look to the Glossopteris flora for the ancestry of Angiosperms during the Secondary period, Darwin's prevision might be justified, though he has given us no clue as to how he arrived at it. It may be true that technically Darwin was not a botanist. But in two pages of the "Origin" he has given us a masterly explanation of "the relationship, with very little identity, between the productions of North America and Europe." (Pages 333, 334.) He showed that this could be accounted for by their migration southwards from a common area, and he told Wallace that he "doubted much whether the now called Palaearctic and Neartic regions ought to be separated." ("Life and Letters", III. page 230.) Catkin-bearing deciduous trees had long been seen to justify Darwin's doubt: oaks, chestnuts, beeches, hazels, hornbeams, birches, alders, willows and poplars are common both to the Old and New World. Newton found that the separate regions could not be sustained for birds, and he is now usually followed in uniting them as the Holartic. One feels inclined to say in reading the two pages, as Lord Kelvin did to a correspondent who asked for some further development of one of his papers, It is all there. We have only to apply the principle to previous geological ages to understand why the flora of the Southern United States preserves a Cretaceous facies. Applying it still further we can understand why, when the northern hemisphere gradually cooled through the Tertiary period, the plants of the Eocene "suggest a comparison of the climate and forests with those of the Malay Archipelago and Tropical America." (Clement Reid, "Encycl. Brit." (10th edition), Vol. XXXI. ("Palaeobotany; Tertiary"), page 435.) Writing to Asa Gray in 1856 with respect to the United States flora, Darwin said that "nothing has surprised me more than the greater generic and specific affinity with East Asia than with West America." ("More Letters", I. page 434.) The recent discoveries of a Tulip tree and a Sassafras in China afford fresh illustrations. A few years later Asa Gray found the explanation in both areas being centres of preservation of the Cretaceous flora from a common origin. It is interesting to note that the paper in which this was enunciated at once established his reputation. In Europe the latitudinal range of the great mountain chains gave the Miocene flora no chance of escape during the Glacial period, and the Mediterranean appears to have equally intercepted the flow of alpine plants to the Atlas. (John Ball in Appendix G, page 438, in "Journal of a Tour in Morocco and the Great Atlas", J.D. Hooker and J. Ball, London, 1878.) In Southern Europe the myrtle, the laurel, the fig and the dwarf-palm are the sole representatives of as many great tropical families. Another great tropical family, the Gesneraceae has left single representatives from the Pyrenees to the Balkans; and in the former a diminutive yam still lingers. These are only illustrations of the evidence which constantly accumulates and which finds no rational explanation except that which Darwin has given to it. The theory of southward migration is the key to the interpretation of the geographical distribution of plants. It derived enormous support from the researches of Heer and has now become an accepted commonplace. Saporta in 1888 described the vegetable kingdom as "emigrant pour suivre une direction determinee et marcher du nord au sud, a la recherche de regions et de stations plus favorables, mieux appropriees aux adaptations acquises, a meme que la temperature terrestre perd ses conditions premieres." ("Origine Paleontologique des arbres", Paris, 1888, page 28.) If, as is so often the case, the theory now seems to be a priori inevitable, the historian of science will not omit to record that the first germ sprang from the brain of Darwin. In attempting this sketch of Darwin's influence on Geographical Distribution, I have found it impossible to treat it from an external point of view. His interest in it was unflagging; all I could say became necessarily a record of that interest and could not be detached from it. He was in more or less intimate touch with everyone who was working at it. In reading the letters we move amongst great names. With an extraordinary charm of persuasive correspondence he was constantly suggesting, criticising and stimulating. It is hardly an exaggeration to say that from the quiet of his study at Down he was founding and directing a wide-world school. POSTSCRIPTUM. Since this essay was put in type Dr Ernst's striking account of the "New Flora of the Volcanic Island of Krakatau" (Cambridge, 1909.) has reached me. All botanists must feel a debt of gratitude to Prof. Seward for his admirable translation of a memoir which in its original form is practically unprocurable and to the liberality of the Cambridge University Press for its publication. In the preceding pages I have traced the laborious research by which the methods of Plant Dispersal were established by Darwin. In the island of Krakatau nature has supplied a crucial experiment which, if it had occurred earlier, would have at once secured conviction of their efficiency. A quarter of a century ago every trace of organic life in the island was "destroyed and buried under a thick covering of glowing stones." Now, it is "again covered with a mantle of green, the growth being in places so luxuriant that it is necessary to cut one's way laboriously through the vegetation." (Op. cit. page 4.) Ernst traces minutely how this has been brought about by the combined action of wind, birds and sea currents, as means of transport. The process will continue, and he concludes:--"At last after a long interval the vegetation on the desolated island will again acquire that wealth of variety and luxuriance which we see in the fullest development which Nature has reached in the primaeval forest in the tropics." (Op. cit. page 72.) The possibility of such a result revealed itself to the insight of Darwin with little encouragement or support from contemporary opinion. One of the most remarkable facts established by Ernst is that this has not been accomplished by the transport of seeds alone. "Tree stems and branches played an important part in the colonisation of Krakatau by plants and animals. Large piles of floating trees, stems, branches and bamboos are met with everywhere on the beach above high-water mark and often carried a considerable distance inland. Some of the animals on the island, such as the fat Iguana (Varanus salvator) which suns itself in the beds of streams, may have travelled on floating wood, possibly also the ancestors of the numerous ants, but certainly plants." (Op. cit. page 56.) Darwin actually had a prevision of this. Writing to Hooker he says:--"Would it not be a prodigy if an unstocked island did not in the course of ages receive colonists from coasts whence the currents flow, trees are drifted and birds are driven by gales?" ("More Letters", I. page 483.) And ten years earlier:--"I must believe in the... whole plant or branch being washed into the sea; with floods and slips and earthquakes; this must continually be happening." ("Life and Letters", II. pages 56, 57.) If we give to "continually" a cosmic measure, can the fact be doubted? All this, in the light of our present knowledge, is too obvious to us to admit of discussion. But it seems to me nothing less than pathetic to see how in the teeth of the obsession as to continental extension, Darwin fought single-handed for what we now know to be the truth. Guppy's heart failed him when he had to deal with the isolated case of Agathis which alone seemed inexplicable by known means of transport. But when we remember that it is a relic of the pre-Angiospermous flora, and is of Araucarian ancestry, it cannot be said that the impossibility, in so prolonged a history, of the bodily transference of cone-bearing branches or even of trees, compels us as a last resort to fall back on continental extension to account for its existing distribution. When Darwin was in the Galapagos Archipelago, he tells us that he fancied himself "brought near to the very act of creation." He saw how new species might arise from a common stock. Krakatau shows us an earlier stage and how by simple agencies, continually at work, that stock might be supplied. It also shows us how the mixed and casual elements of a new colony enter into competition for the ground and become mutually adjusted. The study of Plant Distribution from a Darwinian standpoint has opened up a new field of research in Ecology. The means of transport supply the materials for a flora, but their ultimate fate depends on their equipment for the "struggle for existence." The whole subject can no longer be regarded as a mere statistical inquiry which has seemed doubtless to many of somewhat arid interest. The fate of every element of the earth's vegetation has sooner or later depended on its ability to travel and to hold its own under new conditions. And the means by which it has secured success is an each case a biological problem which demands and will reward the most attentive study. This is the lesson which Darwin has bequeathed to us. It is summed up in the concluding paragraph of the "Origin" ("Origin of Species" (6th edition), page 429.):--"It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us." XVII. GEOGRAPHICAL DISTRIBUTION OF ANIMALS. By Hans Gadow, M.A., Ph.D., F.R.S. Strickland Curator and Lecturer on Zoology in the University of Cambridge. The first general ideas about geographical distribution may be found in some of the brilliant speculations contained in Buffon's "Histoire Naturelle". The first special treatise on the subject was however written in 1777 by E.A.W. Zimmermann, Professor of Natural Science at Brunswick, whose large volume, "Specimen Zoologiae Geographicae Quadrupedum"..., deals in a statistical way with the mammals; important features of the large accompanying map of the world are the ranges of mountains and the names of hundreds of genera indicating their geographical range. In a second work he laid special stress on domesticated animals with reference to the spreading of the various races of Mankind. In the following year appeared the "Philosophia Entomologica" by J.C. Fabricius, who was the first to divide the world into eight regions. In 1803 G.R. Treviranus ("Biologie oder Philosophie der lebenden Natur", Vol. II. Gottingen, 1803.) devoted a long chapter of his great work on "Biologie" to a philosophical and coherent treatment of the distribution of the whole animal kingdom. Remarkable progress was made in 1810 by F. Tiedemann ("Anatomie und Naturgeschichte der Vogel". Heidelberg, 1810.) of Heidelberg. Few, if any, of the many subsequent Ornithologists seem to have appreciated, or known of, the ingenious way in which Tiedemann marshalled his statistics in order to arrive at general conclusions. There are, for instance, long lists of birds arranged in accordance with their occurrence in one or more continents: by correlating the distribution of the birds with their food he concludes "that the countries of the East Indian flora have no vegetable feeders in common with America," and "that it is probably due to the great peculiarity of the African flora that Africa has few phytophagous kinds in common with other countries, whilst zoophagous birds have a far more independent, often cosmopolitan, distribution." There are also remarkable chapters on the influence of environment, distribution, and migration, upon the structure of the Birds! In short, this anatomist dealt with some of the fundamental causes of distribution. Whilst Tiedemann restricted himself to Birds, A. Desmoulins in 1822 wrote a short but most suggestive paper on the Vertebrata, omitting the birds; he combated the view recently proposed by the entomologist Latreille that temperature was the main factor in distribution. Some of his ten main conclusions show a peculiar mixture of evolutionary ideas coupled with the conception of the stability of species: whilst each species must have started from but one creative centre, there may be several "analogous centres of creation" so far as genera and families are concerned. Countries with different faunas, but lying within the same climatic zones, are proof of the effective and permanent existence of barriers preventing an exchange between the original creative centres. The first book dealing with the "geography and classification" of the whole animal kingdom was written by W. Swainson ("A Treatise on the Geography and Classification of Animals", Lardner's "Cabinet Cyclopaedia" London, 1835.) in 1835. He saw in the five races of Man the clue to the mapping of the world into as many "true zoological divisions," and he reconciled the five continents with his mystical quinary circles. Lyell's "Principles of Geology" should have marked a new epoch, since in his "Elements" he treats of the past history of the globe and the distribution of animals in time, and in his "Principles" of their distribution in space in connection with the actual changes undergone by the surface of the world. But as the sub-title of his great work "Modern changes of the Earth and its inhabitants" indicates, he restricted himself to comparatively minor changes, and, emphatically believing in the permanency of the great oceans, his numerous and careful interpretations of the effect of the geological changes upon the dispersal of animals did after all advance the problem but little. Hitherto the marine faunas had been neglected. This was remedied by E. Forbes, who established nine homozoic zones, based mainly on the study of the mollusca, the determining factors being to a great extent the isotherms of the sea, whilst the 25 provinces were given by the configuration of the land. He was followed by J.D. Dana, who, taking principally the Crustacea as a basis, and as leading factors the mean temperatures of the coldest and of the warmest months, established five latitudinal zones. By using these as divisors into an American, Afro-European, Oriental, Arctic and Antarctic realm, most of which were limited by an eastern and western land-boundary, he arrived at about threescore provinces. In 1853 appeared L.K. Schmarda's ("Die geographische Verbreitung der Thiere", Wien, 1853.) two volumes, embracing the whole subject. Various centres of creation being, according to him, still traceable, he formed the hypothesis that these centres were originally islands, which later became enlarged and joined together to form the great continents, so that the original faunas could overlap and mix whilst still remaining pure at their respective centres. After devoting many chapters to the possible physical causes and modes of dispersal, he divided the land into 21 realms which he shortly characterises, e.g. Australia as the only country inhabited by marsupials, monotremes and meliphagous birds. Ten main marine divisions were diagnosed in a similar way. Although some of these realms were not badly selected from the point of view of being applicable to more than one class of animals, they were obviously too numerous for general purposes, and this drawback was overcome, in 1857, by P.L. Sclater. ("On the general Geographical Distribution of the members of the class Aves", "Proc. Linn. Soc." (Zoology II. 1858, pages 130-145.)) Starting with the idea, that "each species must have been created within and over the geographical area, which it now occupies," he concluded "that the most natural primary ontological divisions of the Earth's surface" were those six regions, which since their adoption by Wallace in his epoch-making work, have become classical. Broadly speaking, these six regions are equivalent to the great masses of land; they are convenient terms for geographical facts, especially since the Palaearctic region expresses the unity of Europe with the bulk of Asia. Sclater further brigaded the regions of the Old World as Palaeogaea and the two Americas as Neogaea, a fundamental mistake, justifiable to a certain extent only since he based his regions mainly upon the present distribution of the Passerine birds. Unfortunately these six regions are not of equal value. The Indian countries and the Ethiopian region (Africa south of the Sahara) are obviously nothing but the tropical, southern continuations or appendages of one greater complex. Further, the great eastern mass of land is so intimately connected with North America that this continent has much more in common with Europe and Asia than with South America. Therefore, instead of dividing the world longitudinally as Sclater had done, Huxley, in 1868 ("On the classification and distribution of the Alectoromorphae and Heteromorphae", "Proc. Zool. Soc." 1868, page 294.), gave weighty reasons for dividing it transversely. Accordingly he established two primary divisions, Arctogaea or the North world in a wider sense, comprising Sclater's Indian, African, Palaearctic and Neartic regions; and Notogaea, the Southern world, which he divided into (1) Austro-Columbia (an unfortunate substitute for the neotropical region), (2) Australasia, and (3) New Zealand, the number of big regions thus being reduced to three but for the separation of New Zealand upon rather negative characters. Sclater was the first to accept these four great regions and showed, in 1874 ("The geographical distribution of Mammals", "Manchester Science Lectures", 1874.), that they were well borne out by the present distribution of the Mammals. Although applicable to various other groups of animals, for instance to the tailless Amphibia and to Birds (Huxley himself had been led to found his two fundamental divisions on the distribution of the Gallinaceous birds), the combination of South America with Australia was gradually found to be too sweeping a measure. The obvious and satisfactory solution was provided by W.T. Blanford (Anniversary address (Geological Society, 1889), "Proc. Geol. Soc." 1889-90, page 67; "Quart. Journ." XLVI 1890.), who in 1890 recognised three main divisions, namely Australian, South American, and the rest, for which the already existing terms (although used partly in a new sense, as proposed by an anonymous writer in "Natural Science", III. page 289) "Notogaea," "Neogaea" and "Arctogaea" have been gladly accepted by a number of English writers. After this historical survey of the search for larger and largest or fundamental centres of animal creation, which resulted in the mapping of the world into zoological regions and realms of after all doubtful value, we have to return to the year 1858. The eleventh and twelfth chapters of "The Origin of Species" (1859), dealing with "Geographical Distribution," are based upon a great amount of observation, experiment and reading. As Darwin's main problem was the origin of species, nature's way of making species by gradual changes from others previously existing, he had to dispose of the view, held universally, of the independent creation of each species and at the same time to insist upon a single centre of creation for each species; and in order to emphasise his main point, the theory of descent, he had to disallow convergent, or as they were then called, analogous forms. To appreciate the difficulty of his position we have to take the standpoint of fifty years ago, when the immutability of the species was an axiom and each was supposed to have been created within or over the geographical area which it now occupies. If he once admitted that a species could arise from many individuals instead of from one pair, there was no way of shutting the door against the possibility that these individuals may have been so numerous that they occupied a very large district, even so large that it had become as discontinuous as the distribution of many a species actually is. Such a concession would at once be taken as an admission of multiple, independent, origin instead of descent in Darwin's sense. For the so-called multiple, independently repeated creation of species as an explanation of their very wide and often quite discontinuous distribution, he substituted colonisation from the nearest and readiest source together with subsequent modification and better adaptation to their new home. He was the first seriously to call attention to the many accidental means, "which more properly should be called occasional means of distribution," especially to oceanic islands. His specific, even individual, centres of creation made migrations all the more necessary, but their extent was sadly baulked by the prevailing dogma of the permanency of the oceans. Any number of small changes ("many islands having existed as halting places, of which not a wreck now remains" ("The Origin of Species" (1st edition), page 396.).) were conceded freely, but few, if any, great enough to permit migration of truly terrestrial creatures. The only means of getting across the gaps was by the principle of the "flotsam and jetsam," a theory which Darwin took over from Lyell and further elaborated so as to make it applicable to many kinds of plants and animals, but sadly deficient, often grotesque, in the case of most terrestrial creatures. Another very fertile source was Darwin's strong insistence upon the great influence which the last glacial epoch must have had upon the distribution of animals and plants. Why was the migration of northern creatures southwards of far-reaching and most significant importance? More northerners have established themselves in southern lands than vice versa, because there is such a great mass of land in the north and greater continents imply greater intensity of selection. "The productions of real islands have everywhere largely yielded to continental forms." (Ibid. page 380.)... "The Alpine forms have almost everywhere largely yielded to the more dominant forms generated in the larger areas and more efficient workshops of the North." Let us now pass in rapid survey the influence of the publication of "The Origin of Species" upon the study of Geographical Distribution in its wider sense. Hitherto the following thought ran through the minds of most writers: Wherever we examine two or more widely separated countries their respective faunas are very different, but where two faunas can come into contact with each other, they intermingle. Consequently these faunas represent centres of creation, whence the component creatures have spread peripherally so far as existing boundaries allowed them to do so. This is of course the fundamental idea of "regions." There is not one of the numerous writers who considered the possibility that these intermediate belts might represent not a mixture of species but transitional forms, the result of changes undergone by the most peripheral migrants in adaptation to their new surroundings. The usual standpoint was also that of Pucheran ("Note sur l'equateur zoologique", "Rev. et Mag. de Zoologie", 1855; also several other papers, ibid. 1865, 1866, and 1867.) in 1855. But what a change within the next ten years! Pucheran explains the agreement in coloration between the desert and its fauna as "une harmonie post-etablie"; the Sahara, formerly a marine basin, was peopled by immigrants from the neighbouring countries, and these new animals adapted themselves to the new environment. He also discusses, among other similar questions, the Isthmus of Panama with regard to its having once been a strait. From the same author may be quoted the following passage as a strong proof of the new influence: "By the radiation of the contemporaneous faunas, each from one centre, whence as the various parts of the world successively were formed and became habitable, they spread and became modified according to the local physical conditions." The "multiple" origin of each species as advocated by Sclater and Murray, although giving the species a broader basis, suffered from the same difficulties. There was only one alternative to the old orthodox view of independent creation, namely the bold acceptance of land-connections to an extent for which geological and palaeontological science was not yet ripe. Those who shrank from either view, gave up the problem as mysterious and beyond the human intellect. This was the expressed opinion of men like Swainson, Lyell and Humboldt. Only Darwin had the courage to say that the problem was not insoluble. If we admit "that in the long course of time the individuals of the same species, and likewise of allied species, have proceeded from some one source; then I think all the grand leading facts of geographical distribution are explicable on the theory of migration... together with subsequent modification and the multiplication of new forms." We can thus understand how it is that in some countries the inhabitants "are linked to the extinct beings which formerly inhabited the same continent." We can see why two areas, having nearly the same physical conditions, should often be inhabited by very different forms of life,... and "we can see why in two areas, however distant from each other, there should be a correlation, in the presence of identical species... and of distinct but representative species." ("The Origin of Species" (1st edition), pages 408, 409.) Darwin's reluctance to assume great geological changes, such as a land-connection of Europe with North America, is easily explained by the fact that he restricted himself to the distribution of the present and comparatively recent species. "I do not believe that it will ever be proved that within the recent period continents which are now quite separate, have been continuously, or almost continuously, united with each other, and with the many existing oceanic islands." (Ibid. page 357.) Again, "believing... that our continents have long remained in nearly the same relative position, though subjected to large, but partial oscillations of level," that means to say within the period of existing species, or "within the recent period." (Ibid. page. 370.) The difficulty was to a great extent one of his own making. Whilst almost everybody else believed in the immutability of the species, which implies an enormous age, logically since the dawn of creation, to him the actually existing species as the latest results of evolution, were necessarily something very new, so young that only the very latest of the geological epochs could have affected them. It has since come to our knowledge that a great number of terrestrial "recent" species, even those of the higher classes of Vertebrates, date much farther back than had been thought possible. Many of them reach well into the Miocene, a time since which the world seems to have assumed the main outlines of the present continents. In the year 1866 appeared A. Murray's work on the "Geographical Distribution of Mammals", a book which has perhaps received less recognition than it deserves. His treatment of the general introductory questions marks a considerable advance of our problem, although, and partly because, he did not entirely agree with Darwin's views as laid down in the first edition of "The Origin of Species", which after all was the great impulse given to Murray's work. Like Forbes he did not shrink from assuming enormous changes in the configuration of the continents and oceans because the theory of descent, with its necessary postulate of great migrations, required them. He stated, for instance, "that a Miocene Atlantis sufficiently explains the common distribution of animals and plants in Europe and America up to the glacial epoch." And next he considers how, and by what changes, the rehabilitation and distribution of these lands themselves were effected subsequent to that period. Further, he deserves credit for having cleared up a misunderstanding of the idea of specific centres of creation. Whilst for instance Schmarda assumed without hesitation that the same species, if occurring at places separated by great distances, or apparently insurmountable barriers, had been there created independently (multiple centres), Lyell and Darwin held that each species had only one single centre, and with this view most of us agree, but their starting point was to them represented by one individual, or rather one single pair. According to Murray, on the other hand, this centre of a species is formed by all the individuals of a species, all of which equally undergo those changes which new conditions may impose upon them. In this respect a new species has a multiple origin, but this in a sense very different from that which was upheld by L. Agassiz. As Murray himself puts it: "To my multiple origin, communication and direct derivation is essential. The species is compounded of many influences brought together through many individuals, and distilled by Nature into one species; and, being once established it may roam and spread wherever it finds the conditions of life not materially different from those of its original centre." (Murray, "The Geographical Distribution of Mammals", page 14. London, 1866.) This declaration fairly agrees with more modern views, and it must be borne in mind that the application of the single-centre principle to the genera, families and larger groups in the search for descent inevitably leads to one creative centre for the whole animal kingdom, a condition as unwarrantable as the myth of Adam and Eve being the first representatives of Mankind. It looks as if it had required almost ten years for "The Origin of Species" to show its full effect, since the year 1868 marks the publication of Haeckel's "Naturliche Schoepfungsgeschichte" in addition to other great works. The terms "Oecology" (the relation of organisms to their environment) and "Chorology" (their distribution in space) had been given us in his "Generelle Morphologie" in 1866. The fourteenth chapter of the "History of Creation" is devoted to the distribution of organisms, their chorology, with the emphatic assertion that "not until Darwin can chorology be spoken of as a separate science, since he supplied the acting causes for the elucidation of the hitherto accumulated mass of facts." A map (a "hypothetical sketch") shows the monophyletic origin and the routes of distribution of Man. Natural Selection may be all-mighty, all-sufficient, but it requires time, so much that the countless aeons required for the evolution of the present fauna were soon felt to be one of the most serious drawbacks of the theory. Therefore every help to ease and shorten this process should have been welcomed. In 1868 M. Wagner (The first to formulate clearly the fundamental idea of a theory of migration and its importance in the origin of new species was L. von Buch, who in his "Physikalische Beschreibung der Canarischen Inseln", written in 1825, wrote as follows: "Upon the continents the individuals of the genera by spreading far, form, through differences of the locality, food and soil, varieties which finally become constant as new species, since owing to the distances they could never be crossed with other varieties and thus be brought back to the main type. Next they may again, perhaps upon different roads, return to the old home where they find the old type likewise changed, both having become so different that they can interbreed no longer. Not so upon islands, where the individuals shut up in narrow valleys or within narrow districts, can always meet one another and thereby destroy every new attempt towards the fixing of a new variety." Clearly von Buch explains here why island types remain fixed, and why these types themselves have become so different from their continental congeners.--Actually von Buch is aware of a most important point, the difference in the process of development which exists between a new species b, which is the result of an ancestral species a having itself changed into b and thereby vanished itself, and a new species c which arose through separation out of the same ancestral a, which itself persists as such unaltered. Von Buch's prophetic view seems to have escaped Lyell's and even Wagner's notice.) came to the rescue with his "Darwin'sche Theorie und das Migrations-Gesetz der Organismen". (Leipzig, 1868.) He shows that migration, i.e. change of locality, implies new environmental conditions (never mind whether these be new stimuli to variation, or only acting as their selectors or censors), and moreover secures separation from the original stock and thus eliminates or lessens the reactionary dangers of panmixia. Darwin accepted Wagner's theory as "advantageous." Through the heated polemics of the more ardent selectionists Wagner's theory came to grow into an alternative instead of a help to the theory of selectional evolution. Separation is now rightly considered a most important factor by modern students of geographical distribution. For the same year, 1868, we have to mention Huxley, whose Arctogaea and Notogaea are nothing less than the reconstructed main masses of land of the Mesozoic period. Beyond doubt the configuration of land at that remote period has left recognisable traces in the present continents, but whether they can account for the distribution of such a much later group as the Gallinaceous birds is more than questionable. In any case he took for his text a large natural group of birds, cosmopolitan as a whole, but with a striking distribution. The Peristeropodes, or pigeon-footed division, are restricted to the Australian and Neotropical regions, in distinction to the Alectoropodes (with the hallux inserted at a level above the front toes) which inhabit the whole of the Arctogaea, only a few members having spread into the South World. Further, as Asia alone has its Pheasants and allies, so is Africa characterised by its Guinea-fowls and relations, America has the Turkey as an endemic genus, and the Grouse tribe in a wider sense has its centre in the holarctic region: a splendid object lesson of descent, world-wide spreading and subsequent differentiation. Huxley, by the way, was the first--at least in private talk--to state that it will be for the morphologist, the well-trained anatomist, to give the casting vote in questions of geographical distribution, since he alone can determine whether we have to deal with homologous, or analogous, convergent, representative forms. It seems late to introduce Wallace's name in 1876, the year of the publication of his standard work. ("The Geographical Distribution of Animals", 2 vols. London, 1876.) We cannot do better than quote the author's own words, expressing the hope that his "book should bear a similar relation to the eleventh and twelfth chapters of the "Origin of Species" as Darwin's "Animals and Plants under Domestication" does to the first chapter of that work," and to add that he has amply succeeded. Pleading for a few primary centres he accepts Sclater's six regions and does not follow Huxley's courageous changes which Sclater himself had accepted in 1874. Holding the view of the permanence of the oceans he accounts for the colonisation of outlying islands by further elaborating the views of Lyell and Darwin, especially in his fascinating "Island Life", with remarkable chapters on the Ice Age, Climate and Time and other fundamental factors. His method of arriving at the degree of relationship of the faunas of the various regions is eminently statistical. Long lists of genera determine by their numbers the affinity and hence the source of colonisation. In order to make sure of his material he performed the laborious task of evolving a new classification of the host of Passerine birds. This statistical method has been followed by many authors, who, relying more upon quantity than quality, have obscured the fact that the key to the present distribution lies in the past changes of the earth's surface. However, with Wallace begins the modern study of the geographical distribution of animals and the sudden interest taken in this subject by an ever widening circle of enthusiasts far beyond the professional brotherhood. A considerable literature has since grown up, almost bewildering in its range, diversity of aims and style of procedure. It is a chaos, with many paths leading into the maze, but as yet very few take us to a position commanding a view of the whole intricate terrain with its impenetrable tangle and pitfalls. One line of research, not initiated but greatly influenced by Wallace's works, became so prominent as to almost constitute a period which may be characterised as that of the search by specialists for either the justification or the amending of his regions. As class after class of animals was brought up to reveal the secret of the true regions, some authors saw in their different results nothing but the faultiness of previously established regions; others looked upon eventual agreements as their final corroboration, especially when for instance such diverse groups as mammals and scorpions could, with some ingenuity, be made to harmonise. But the obvious result of all these efforts was the growing knowledge that almost every class seemed to follow principles of its own. The regions tallied neither in extent nor in numbers, although most of them gravitated more and more towards three centres, namely Australia, South America and the rest of the world. Still zoologists persisted in the search, and the various modes and capabilities of dispersal of the respective groups were thought sufficient explanation of the divergent results in trying to bring the mapping of the world under one scheme. Contemporary literature is full of devices for the mechanical dispersal of animals. Marine currents, warm and cold, were favoured all the more since they showed the probable original homes of the creatures in question. If these could not stand sea-water, they floated upon logs or icebergs, or they were blown across by storms; fishes were lifted over barriers by waterspouts, and there is on record even an hypothetical land tortoise, full of eggs, which colonised an oceanic island after a perilous sea voyage upon a tree trunk. Accidents will happen, and beyond doubt many freaks of discontinuous distribution have to be accounted for by some such means. But whilst sufficient for the scanty settlers of true oceanic islands, they cannot be held seriously to account for the rich fauna of a large continent, over which palaeontology shows us that the immigrants have passed like waves. It should also be borne in mind that there is a great difference between flotsam and jetsam. A current is an extension of the same medium and the animals in it may suffer no change during even a long voyage, since they may be brought from one litoral to another where they will still be in the same or but slightly altered environment. But the jetsam is in the position of a passenger who has been carried off by the wrong train. Almost every year some American land birds arrive at our western coasts and none of them have gained a permanent footing although such visits must have taken place since prehistoric times. It was therefore argued that only those groups of animals should be used for locating and defining regions which were absolutely bound to the soil. This method likewise gave results not reconcilable with each other, even when the distribution of fossils was taken into account, but it pointed to the absolute necessity of searching for former land-connections regardless of their extent and the present depths to which they may have sunk. That the key to the present distribution lies in the past had been felt long ago, but at last it was appreciated that the various classes of animals and plants have appeared in successive geological epochs and also at many places remote from each other. The key to the distribution of any group lies in the configuration of land and water of that epoch in which it made its first appearance. Although this sounds like a platitude, it has frequently been ignored. If, for argument's sake, Amphibia were evolved somewhere upon the great southern land-mass of Carboniferous times (supposed by some to have stretched from South America across Africa to Australia), the distribution of this developing class must have proceeded upon lines altogether different from that of the mammals which dated perhaps from lower Triassic times, when the old south continental belt was already broken up. The broad lines of this distribution could never coincide with that of the other, older class, no matter whether the original mammalian centre was in the Afro-Indian, Australian, or Brazilian portion. If all the various groups of animals had come into existence at the same time and at the same place, then it would be possible, with sufficient geological data, to construct a map showing the generalised results applicable to the whole animal kingdom. But the premises are wrong. Whatever regions we may seek to establish applicable to all classes, we are necessarily mixing up several principles, namely geological, historical, i.e. evolutionary, with present day statistical facts. We might as well attempt one compound picture representing a chick's growth into an adult bird and a child's growth into manhood. In short there are no general regions, not even for each class separately, unless this class be one which is confined to a comparatively short geological period. Most of the great classes have far too long a history and have evolved many successive main groups. Let us take the mammals. Marsupials live now in Australia and in both Americas, because they already existed in Mesozoic times; Ungulata existed at one time or other all over the world except in Australia, because they are post-Cretaceous; Insectivores, although as old as any Placentalia, are cosmopolitan excepting South America and Australia; Stags and Bears, as examples of comparatively recent Arctogaeans, are found everywhere with the exception of Ethiopia and Australia. Each of these groups teaches a valuable historical lesson, but when these are combined into the establishment of a few mammalian "realms," they mean nothing but statistical majorities. If there is one at all, Australia is such a realm backed against the rest of the world, but as certainly it is not a mammalian creative centre! Well then, if the idea of generally applicable regions is a mare's nest, as was the search for the Holy Grail, what is the object of the study of geographical distribution? It is nothing less than the history of the evolution of life in space and time in the widest sense. The attempt to account for the present distribution of any group of organisms involves the aid of every branch of science. It bids fair to become a history of the world. It started in a mild, statistical way, restricting itself to the present fauna and flora and to the present configuration of land and water. Next came Oceanography concerned with the depths of the seas, their currents and temperatures; then enquiries into climatic changes, culminating in irreconcilable astronomical hypotheses as to glacial epochs; theories about changes of the level of the seas, mainly from the point of view of the physicist and astronomer. Then came more and more to the front the importance of the geological record, hand in hand with the palaeontological data and the search for the natural affinities, the genetic system of the organisms. Now and then it almost seems as if the biologists had done their share by supplying the problems and that the physicists and geologists would settle them, but in reality it is not so. The biologists not only set the problems, they alone can check the offered solutions. The mere fact of palms having flourished in Miocene Spitzbergen led to an hypothetical shifting of the axis of the world rather than to the assumption, by way of explanation, that the palms themselves might have changed their nature. One of the most valuable aids in geological research, often the only means for reconstructing the face of the earth in by-gone periods, is afforded by fossils, but only the morphologist can pronounce as to their trustworthiness as witnesses, because of the danger of mistaking analogous for homologous forms. This difficulty applies equally to living groups, and it is so important that a few instances may not be amiss. There is undeniable similarity between the faunas of Madagascar and South America. This was supported by the Centetidae and Dendrobatidae, two entire "families," as also by other facts. The value of the Insectivores, Solenodon in Cuba, Centetes in Madagascar, has been much lessened by their recognition as an extremely ancient group and as a case of convergence, but if they are no longer put into the same family, this amendment is really to a great extent due to their widely discontinuous distribution. The only systematic difference of the Dendrobatidae from the Ranidae is the absence of teeth, morphologically a very unimportant character, and it is now agreed, on the strength of their distribution, that these little arboreal, conspicuously coloured frogs, Dendrobates in South America, Mantella in Madagascar, do not form a natural group, although a third genus, Cardioglossa in West Africa, seems also to belong to them. If these creatures lived all on the same continent, we should unhesitatingly look upon them as forming a well-defined, natural little group. On the other hand the Aglossa, with their three very divergent genera, namely Pipa in South America, Xenopus and Hymenochirus in Africa, are so well characterised as one ancient group that we use their distribution unhesitatingly as a hint of a former connection between the two continents. We are indeed arguing in vicious circles. The Ratitae as such are absolutely worthless since they are a most heterogeneous assembly, and there are untold groups, of the artificiality of which many a zoo-geographer had not the slightest suspicion when he took his statistical material, the genera and families, from some systematic catalogues or similar lists. A lamentable instance is that of certain flightless Rails, recently extinct or sub-fossil, on the isalnds of Mauritius, Rodriguez and Chatham. Being flightless they have been used in support of a former huge Antarctic continent, instead of ruling them out of court as Rails which, each in its island, have lost the power of flight, a process which must have taken place so recently that it is difficult, upon morphological grounds, to justify their separation into Aphanapteryx in Mauritius, Erythromachus in Rodriguez and Diaphorapteryx on Chatham Island. Morphologically they may well form but one genus, since they have sprung from the same stock and have developed upon the same lines; they are therefore monogenetic: but since we know that they have become what they are independently of each other (now unlike any other Rails), they are polygenetic and therefore could not form one genus in the old Darwinian sense. Further, they are not a case of convergence, since their ancestry is not divergent but leads into the same stratum. THE RECONSTRUCTION OF THE GEOGRAPHY OF SUCCESSIVE EPOCHS. A promising method is the study by the specialist of a large, widely distributed group of animals from an evolutionary point of view. Good examples of this method are afforded by A.E. Ortmann's ("The geographical distribution of Freshwater Decapods and its bearing upon ancient geography", "Proc. Amer. Phil. Soc." Vol. 41, 1902.) exhaustive paper and by A.W. Grabau's "Phylogeny of Fusus and its Allies" ("Smithsonian Misc. Coll." 44, 1904.) After many important groups of animals have been treated in this way--as yet sparingly attempted--the results as to hypothetical land-connections etc. are sure to be corrective and supplementary, and their problems will be solved, since they are not imaginary. The same problems are attacked, in the reverse way, by starting with the whole fauna of a country and thence, so to speak, letting the research radiate. Some groups will be considered as autochthonous, others as immigrants, and the directions followed by them will be inquired into; the search may lead far and in various directions, and by comparison of results, by making compound maps, certain routes will assume definite shape, and if they lead across straits and seas they are warrants to search for land-connections in the past. (A fair sample of this method is C.H. Eigenmann's "The Freshwater Fishes of South and Middle America", "Popular Science Monthly", Vol. 68, 1906.) There are now not a few maps purporting to show the outlines of land and water at various epochs. Many of these attempts do not tally with each other, owing to the lamentable deficiencies of geological and fossil data, but the bolder the hypothetical outlines are drawn, the better, and this is preferable to the insertion of bays and similar detail which give such maps a fallacious look of certainty where none exists. Moreover it must be borne in mind that, when we draw a broad continental belt across an ocean, this belt need never have existed in its entirety at any one time. The features of dispersal, intended to be explained by it, would be accomplished just as well by an unknown number of islands which have joined into larger complexes while elsewhere they subsided again: like pontoon-bridges which may be opened anywhere, or like a series of superimposed dissolving views of land and sea-scapes. Hence the reconstructed maps of Europe, the only continent tolerably known, show a considerable number of islands in puzzling changes, while elsewhere, e.g. in Asia, we have to be satisfied with sweeping generalisations. At present about half-a-dozen big connections are engaging our attention, leaving as comparatively settled the extent and the duration of such minor "bridges" as that between Africa and Madagascar, Tasmania and Australia, the Antilles and Central America, Europe and North Africa. (Not a few of those who are fascinated by, and satisfied with, the statistical aspect of distribution still have a strong dislike to the use of "bridges" if these lead over deep seas, and they get over present discontinuous occurrences by a former "universal or sub-universal distribution" of their groups.) This is indeed an easy method of cutting the knot, but in reality they shunt the question only a stage or two back, never troubling to explain how their groups managed to attain to that sub-universal range; or do they still suppose that the whole world was originally one paradise where everything lived side by side, until sin and strife and glacial epochs left nothing but scattered survivors? The permanence of the great ocean-basins had become a dogma since it was found that a universal elevation of the land to the extent of 100 fathoms would produce but little changes, and when it was shown that even the 1000 fathom-line followed the great masses of land rather closely, and still leaving the great basins (although transgression of the sea to the same extent would change the map of the world beyond recognition), by general consent one mile was allowed as the utmost speculative limit of subsidence. Naturally two or three miles, the average depth of the oceans, seems enormous, and yet such a difference in level is as nothing in comparison with the size of the Earth. On a clay model globe ten feet in diameter an ocean bed three miles deep would scarcely be detected, and the highest mountains would be smaller than the unavoidable grains in the glazed surface of our model. There are but few countries which have not be submerged at some time or other. CONNECTION OF SOUTH EASTERN ASIA WITH AUSTRALIA. Neumayr's Sino-Australian continent during mid-Mesozoic times was probably a much changing Archipelago, with final separations subsequent to the Cretaceous period. Henceforth Australasia was left to its own fate, but for a possible connection with the antarctic continent. AFRICA, MADAGASCAR, INDIA. The "Lemuria" of Sclater and Haeckel cannot have been more than a broad bridge in Jurassic times; whether it was ever available for the Lemurs themselves must depend upon the time of its duration, the more recent the better, but it is difficult to show that it lasted into the Miocene. AFRICA AND SOUTH AMERICA. Since the opposite coasts show an entire absence of marine fossils and deposits during the Mesozoic period, whilst further north and south such are known to exist and are mostly identical on either side, Neumayr suggested the existence of a great Afro-Son American mass of land during the Jurassic epoch. Such land is almost a necessity and is supported by many facts; it would easily explain the distribution of numerous groups of terrestrial creatures. Moreover to the north of this hypothetical land, somewhere across from the Antilles and Guiana to North Africa and South Western Europe, existed an almost identical fauna of Corals and Molluscs, indicating either a coast-line or a series of islands interrupted by shallow seas, just as one would expect if, and when, a Brazil-Ethiopian mass of land were breaking up. Lastly from Central America to the Mediterranean stretches one of the Tertiary tectonic lines of the geologists. Here also the great question is how long this continent lasted. Apparently the South Atlantic began to encroach from the south so that by the later Cretaceous epoch the land was reduced to a comparatively narrow Brazil-West Africa, remnants of which persisted certainly into the early Tertiary, until the South Atlantic joined across the equator with the Atlantic portion of the "Thetys," leaving what remained of South America isolated from the rest of the world. ANTARCTIC CONNECTIONS. Patagonia and Argentina seem to have joined Antartica during the Cretaceous epoch, and this South Georgian bridge had broken down again by mid-Tertiary times when South America became consolidated. The Antarctic continent, presuming that it existed, seems also to have been joined, by way of Tasmania, with Australia, also during the Cretaceous epoch, and it is assumed that the great Australia-Antarctic-Patagonian land was severed first to the south of Tasmania and then at the South Georgian bridge. No connection, and this is important, is indicated between Antarctica and either Africa or Madagascar. So far we have followed what may be called the vicissitudes of the great Permo-Carboniferous Gondwana land in its fullest imaginary extent, an enormous equatorial and south temperate belt from South America to Africa, South India and Australia, which seems to have provided the foundation of the present Southern continents, two of which temporarily joined Antarctica, of which however we know nothing except that it exists now. Let us next consider the Arctic and periarctic lands. Unfortunately very little is known about the region within the arctic circle. If it was all land, or more likely great changing archipelagoes, faunistic exchange between North America, Europe and Siberia would present no difficulties, but there is one connection which engages much attention, namely a land where now lies the North temperate and Northern part of the Atlantic ocean. How far south did it ever extend and what is the latest date of a direct practicable communication, say from North Western Europe to Greenland? Connections, perhaps often interrupted, e.g. between Greenland and Labrador, at another time between Greenland and Scandinavia, seem to have existed at least since the Permo-Carboniferous epoch. If they existed also in late Cretaceous and in Tertiary times, they would of course easily explain exchanges which we know to have repeatedly taken place between America and Europe, but they are not proved thereby, since most of these exchanges can almost as easily have occurred across the polar regions, and others still more easily by repeated junction of Siberia with Alaska. Let us now describe a hypothetical case based on the supposition of connecting bridges. Not to work in a circle, we select an important group which has not served as a basis for the reconstruction of bridges; and it must be a group which we feel justified in assuming to be old enough to have availed itself of ancient land-connections. The occurrence of one species of Peripatus in the whole of Australia, Tasmania and New Zealand (the latter being joined to Australia by way of New Britain in Cretaceous times but not later) puts the genus back into this epoch, no unsatisfactory assumption to the morphologist. The apparent absence of Peripatus in Madagascar indicates that it did not come from the east into Africa, that it was neither Afro-Indian, nor Afro-Australian; nor can it have started in South America. We therefore assume as its creative centre Australia or Malaya in the Cretaceous epoch, whence its occurrence in Sumatra, Malay Peninsula, New Britain, New Zealand and Australia is easily explained. Then extension across Antarctica to Patagonia and Chile, whence it could spread into the rest of South America as this became consolidated in early Tertiary times. For getting to the Antilles and into Mexico it would have to wait until the Miocene, but long before that time it could arrive in Africa, there surviving as a Congolese and a Cape species. This story is unsupported by a single fossil. Peripatus may have been "sub-universal" all over greater Gondwana land in Carboniferous times, and then its absence from Madagascar would be difficult to explain, but the migrations suggested above amount to little considering that the distance from Tasmania to South America could be covered in far less time than that represented by the whole of the Eocene epoch alone. There is yet another field, essentially the domain of geographical distribution, the cultivation of which promises fair to throw much light upon Nature's way of making species. This is the study of the organisms with regard to their environment. Instead of revealing pedigrees or of showing how and when the creatures got to a certain locality, it investigates how they behaved to meet the ever changing conditions of their habitats. There is a facies, characteristic of, and often peculiar to, the fauna of tropical moist forests, another of deserts, of high mountains, of underground life and so forth; these same facies are stamped upon whole associations of animals and plants, although these may be--and in widely separated countries generally are--drawn from totally different families of their respective orders. It does not go to the root of the matter to say that these facies have been brought about by the extermination of all the others which did not happen to fit into their particular environment. One might almost say that tropical moist forests must have arboreal frogs and that these are made out of whatever suitable material happened to be available; in Australia and South America Hylidae, in Africa Ranidae, since there Hylas are absent. The deserts must have lizards capable of standing the glare, the great changes of temperature, of running over or burrowing into the loose sand. When as in America Iguanids are available, some of these are thus modified, while in Africa and Asia the Agamids are drawn upon. Both in the Damara and in the Transcaspian deserts, a Gecko has been turned into a runner upon sand! We cannot assume that at various epochs deserts, and at others moist forests were continuous all over the world. The different facies and associations were developed at various times and places. Are we to suppose that, wherever tropical forests came into existence, amongst the stock of humivagous lizards were always some which presented those nascent variations which made them keep step with the similarly nascent forests, the overwhelming rest being eliminated? This principle would imply that the same stratum of lizards always had variations ready to fit any changed environment, forests and deserts, rocks and swamps. The study of Ecology indicates a different procedure, a great, almost boundless plasticity of the organism, not in the sense of an exuberant moulding force, but of a readiness to be moulded, and of this the "variations" are the visible outcome. In most cases identical facies are produced by heterogeneous convergences and these may seem to be but superficial, affecting only what some authors are pleased to call the physiological characters; but environment presumably affects first those parts by which the organism comes into contact with it most directly, and if the internal structures remain unchanged, it is not because these are less easily modified but because they are not directly affected. When they are affected, they too change deeply enough. That the plasticity should react so quickly--indeed this very quickness seems to have initiated our mistaking the variations called forth for something performed--and to the point, is itself the outcome of the long training which protoplasm has undergone since its creation. In Nature's workshop he does not succeed who has ready an arsenal of tools for every conceivable emergency, but he who can make a tool at the spur of the moment. The ordeal of the practical test is Charles Darwin's glorious conception of Natural Selection. XVIII. DARWIN AND GEOLOGY. By J.W. Judd, C.B., LL.D., F.R.S. (Mr Francis Darwin has related how his father occasionally came up from Down to spend a few days with his brother Erasmus in London, and, after his brother's death, with his daughter, Mrs Litchfield. On these occasions, it was his habit to arrange meetings with Huxley, to talk over zoological questions, with Hooker, to discuss botanical problems, and with Lyell to hold conversations on geology. After the death of Lyell, Darwin, knowing my close intimacy with his friend during his later years, used to ask me to meet him when he came to town, and "talk geology." The "talks" took place sometimes at Jermyn Street Museum, at other times in the Royal College of Science, South Kensington; but more frequently, after having lunch with him, at his brother's or his daughter's house. On several occasions, however, I had the pleasure of visiting him at Down. In the postscript of a letter (of April 15, 1880) arranging one of these visits, he writes: "Since poor, dear Lyell's death, I rarely have the pleasure of geological talk with anyone.") In one of the very interesting conversations which I had with Charles Darwin during the last seven years of his life, he asked me in a very pointed manner if I were able to recall the circumstances, accidental or otherwise, which had led me to devote myself to geological studies. He informed me that he was making similar inquiries of other friends, and I gathered from what he said that he contemplated at that time a study of the causes producing SCIENTIFIC BIAS in individual minds. I have no means of knowing how far this project ever assumed anything like concrete form, but certain it is that Darwin himself often indulged in the processes of mental introspection and analysis; and he has thus fortunately left us--in his fragments of autobiography and in his correspondence--the materials from which may be reconstructed a fairly complete history of his own mental development. There are two perfectly distinct inquiries which we have to undertake in connection with the development of Darwin's ideas on the subject of evolution: FIRST. How, when, and under what conditions was Darwin led to a conviction that species were not immutable, but were derived from pre-existing forms? SECONDLY. By what lines of reasoning and research was he brought to regard "natural selection" as a vera causa in the process of evolution? It is the first of these inquiries which specially interests the geologist; though geology undoubtedly played a part--and by no means an insignificant part--in respect to the second inquiry. When, indeed, the history comes to be written of that great revolution of thought in the nineteenth century, by which the doctrine of evolution, from being the dream of poets and visionaries, gradually grew to be the accepted creed of naturalists, the paramount influence exerted by the infant science of geology--and especially that resulting from the publication of Lyell's epoch-making work, the "Principles of Geology"--cannot fail to be regarded as one of the leading factors. Herbert Spencer in his "Autobiography" bears testimony to the effect produced on his mind by the recently published "Principles", when, at the age of twenty, he had already begun to speculate on the subject of evolution (Herbert Spencer's "Autobiography", London, 1904, Vol. I. pages 175-177.); and Alfred Russel Wallace is scarcely less emphatic concerning the part played by Lyell's teaching in his scientific education. (See "My Life; a record of Events and Opinions", London, 1905, Vol. I. page 355, etc. Also his review of Lyell's "Principles" in "Quarterly Review" (Vol. 126), 1869, pages 359-394. See also "The Darwin-Wallace Celebration by the Linnean Society" (1909), page 118.) Huxley wrote in 1887 "I owe more than I can tell to the careful study of the "Principles of Geology" in my young days." ("Science and Pseudo Science"; "Collected Essays", London, 1902, Vol. V. page 101.) As for Charles Darwin, he never tired--either in his published writings, his private correspondence or his most intimate conversations--of ascribing the awakening of his enthusiasm and the direction of his energies towards the elucidation of the problem of development to the "Principles of Geology" and the personal influence of its author. Huxley has well expressed what the author of the "Origin of Species" so constantly insisted upon, in the statements "Darwin's greatest work is the outcome of the unflinching application to Biology of the leading idea and the method applied in the "Principles" to Geology ("Proc. Roy. Soc." Vol. XLIV. (1888), page viii.; "Collected Essays" II. page 268, 1902.), and "Lyell, for others, as for myself, was the chief agent in smoothing the road for Darwin." ("Life and Letters of Charles Darwin" II. page 190.) We propose therefore to consider, first, what Darwin owed to geology and its cultivators, and in the second place how he was able in the end so fully to pay a great debt which he never failed to acknowledge. Thanks to the invaluable materials contained in the "Life and Letters of Charles Darwin" (3 vols.) published by Mr Francis Darwin in 1887; and to "More Letters of Charles Darwin" (2 vols.) issued by the same author, in conjunction with Professor A.C. Seward, in 1903, we are permitted to follow the various movements in Darwin's mind, and are able to record the story almost entirely in his own words. (The first of these works is indicated in the following pages by the letters "L.L."; the second by "M.L.") From the point of view of the geologist, Darwin's life naturally divides itself into four periods. In the first, covering twenty-two years, various influences were at work militating, now for and now against, his adoption of a geological career; in the second period--the five memorable years of the voyage of the "Beagle"--the ardent sportsman with some natural-history tastes, gradually became the most enthusiastic and enlightened of geologists; in the third period, lasting ten years, the valuable geological recruit devoted nearly all his energies and time to geological study and discussion and to preparing for publication the numerous observations made by him during the voyage; the fourth period, which covers the latter half of his life, found Darwin gradually drawn more and more from geological to biological studies, though always retaining the deepest interest in the progress and fortunes of his "old love." But geologists gladly recognise the fact that Darwin immeasurably better served their science by this biological work, than he could possibly have done by confining himself to purely geological questions. From his earliest childhood, Darwin was a collector, though up to the time when, at eight years of age, he went to a preparatory school, seals, franks and similar trifles appear to have been the only objects of his quest. But a stone, which one of his schoolfellows at that time gave to him, seems to have attracted his attention and set him seeking for pebbles and minerals; as the result of this newly acquired taste, he says (writing in 1838) "I distinctly recollect the desire I had of being able to know something about every pebble in front of the hall door--it was my earliest and only geological aspiration at that time." ("M.L." I. page 3.) He further suspects that while at Mr Case's school "I do not remember any mental pursuits except those of collecting stones," etc... "I was born a naturalist." ("M.L." I. page 4.) The court-yard in front of the hall door at the Mount House, Darwin's birthplace and the home of his childhood, is surrounded by beds or rockeries on which lie a number of pebbles. Some of these pebbles (in quite recent times as I am informed) have been collected to form a "cobbled" space in front of the gate in the outer wall, which fronts the hall door; and a similar "cobbled area," there is reason to believe, may have existed in Darwin's childhood before the door itself. The pebbles, which were obtained from a neighbouring gravel-pit, being derived from the glacial drift, exhibit very striking differences in colour and form. It was probably this circumstance which awakened in the child his love of observation and speculation. It is certainly remarkable that "aspirations" of the kind should have arisen in the mind of a child of 9 or 10! When he went to Shrewsbury School, he relates "I continued collecting minerals with much zeal, but quite unscientifically,--all that I cared about was a new-NAMED mineral, and I hardly attempted to classify them." ("L.L." I. page 34.) There has stood from very early times in Darwin's native town of Shrewsbury, a very notable boulder which has probably marked a boundary and is known as the "Bell-stone"--giving its name to a house and street. Darwin tells us in his "Autobiography" that while he was at Shrewsbury School at the age of 13 or 14 "an old Mr Cotton in Shropshire, who knew a good deal about rocks" pointed out to me "... the 'bell-stone'; he told me that there was no rock of the same kind nearer than Cumberland or Scotland, and he solemnly assured me that the world would come to an end before anyone would be able to explain how this stone came where it now lay"! Darwin adds "This produced a deep impression on me, and I meditated over this wonderful stone." ("L.L." I. page 41.) The "bell-stone" has now, owing to the necessities of building, been removed a short distance from its original site, and is carefully preserved within the walls of a bank. It is a block of irregular shape 3 feet long and 2 feet wide, and about 1 foot thick, weighing probably not less than one-third of a ton. By the courtesy of the directors of the National Provincial Bank of England, I have been able to make a minute examination of it, and Professors Bonney and Watts, with Mr Harker and Mr Fearnsides have given me their valuable assistance. The rock is a much altered andesite and was probably derived from the Arenig district in North Wales, or possibly from a point nearer the Welsh Border. (I am greatly indebted to the Managers of the Bank at Shrewsbury for kind assistance in the examination of this interesting memorial: and Mr H.T. Beddoes, the Curator of the Shrewsbury Museum, has given me some archaeological information concerning the stone. Mr Richard Cotton was a good local naturalist, a Fellow both of the Geological and Linnean Societies; and to the officers of these societies I am indebted for information concerning him. He died in 1839, and although he does not appear to have published any scientific papers, he did far more for science by influencing the career of the school boy!) It was of course brought to where Shrewsbury now stands by the agency of a glacier--as Darwin afterwards learnt. We can well believe from the perusal of these reminiscences that, at this time, Darwin's mind was, as he himself says, "prepared for a philosophical treatment of the subject" of Geology. ("L.L." I. page 41.) When at the age of 16, however, he was entered as a medical student at Edinburgh University, he not only did not get any encouragement of his scientific tastes, but was positively repelled by the ordinary instruction given there. Dr Hope's lectures on Chemistry, it is true, interested the boy, who with his brother Erasmus had made a laboratory in the toolhouse, and was nicknamed "Gas" by his schoolfellows, while undergoing solemn and public reprimand from Dr Butler at Shrewsbury School for thus wasting his time. ("L.L." I. page 35.) But most of the other Edinburgh lectures were "intolerably dull," "as dull as the professors" themselves, "something fearful to remember." In after life the memory of these lectures was like a nightmare to him. He speaks in 1840 of Jameson's lectures as something "I... for my sins experienced!" ("L.L." I. page 340.) Darwin especially signalises these lectures on Geology and Zoology, which he attended in his second year, as being worst of all "incredibly dull. The sole effect they produced on me was the determination never so long as I lived to read a book on Geology, or in any way to study the science!" ("L.L." I. page 41.) The misfortune was that Edinburgh at that time had become the cockpit in which the barren conflict between "Neptunism" and "Plutonism" was being waged with blind fury and theological bitterness. Jameson and his pupils, on the one hand, and the friends and disciples of Hutton, on the other, went to the wildest extremes in opposing each other's peculiar tenets. Darwin tells us that he actually heard Jameson "in a field lecture at Salisbury Craigs, discoursing on a trap-dyke, with amygdaloidal margins and the strata indurated on each side, with volcanic rocks all around us, say that it was a fissure filled with sediment from above, adding with a sneer that there were men who maintained that it had been injected from beneath in a molten condition." ("L.L." I. pages 41-42.) "When I think of this lecture," added Darwin, "I do not wonder that I determined never to attend to Geology." (This was written in 1876 and Darwin had in the summer of 1839 revisited and carefully studied the locality ("L.L." I. page 290.) It is probable that most of Jameson's teaching was of the same controversial and unilluminating character as this field-lecture at Salisbury Craigs. There can be no doubt that, while at Edinburgh, Darwin must have become acquainted with the doctrines of the Huttonian School. Though so young, he mixed freely with the scientific society of the city, Macgillivray, Grant, Leonard Horner, Coldstream, Ainsworth and others being among his acquaintances, while he attended and even read papers at the local scientific societies. It is to be feared, however, that what Darwin would hear most of, as characteristic of the Huttonian teaching, would be assertions that chalk-flints were intrusions of molten silica, that fossil wood and other petrifactions had been impregnated with fused materials, that heat--but never water--was always the agent by which the induration and crystallisation of rock-materials (even siliceous conglomerate, limestone and rock-salt) had been effected! These extravagant "anti-Wernerian" views the young student might well regard as not one whit less absurd and repellant than the doctrine of the "aqueous precipitation" of basalt. There is no evidence that Darwin, even if he ever heard of them, was in any way impressed, in his early career, by the suggestive passages in Hutton and Playfair, to which Lyell afterwards called attention, and which foreshadowed the main principles of Uniformitarianism. As a matter of fact, I believe that the influence of Hutton and Playfair in the development of a philosophical theory of geology has been very greatly exaggerated by later writers on the subject. Just as Wells and Matthew anticipated the views of Darwin on Natural Selection, but without producing any real influence on the course of biological thought, so Hutton and Playfair adumbrated doctrines which only became the basis of vivifying theory in the hands of Lyell. Alfred Russel Wallace has very justly remarked that when Lyell wrote the "Principles of Geology", "the doctrines of Hutton and Playfair, so much in advance of their age, seemed to be utterly forgotten." ("Quarterly Review", Vol. CXXVI. (1869), page 363.) In proof of this it is only necessary to point to the works of the great masters of English geology, who preceded Lyell, in which the works of Hutton and his followers are scarcely ever mentioned. This is true even of the "Researches in Theoretical Geology" and the other works of the sagacious De la Beche. (Of the strength and persistence of the prejudice felt against Lyell's views by his contemporaries, I had a striking illustration some little time after Lyell's death. One of the old geologists who in the early years of the century had done really good work in connection with the Geological Society expressed a hope that I was not "one of those who had been carried away by poor Lyell's fads." My surprise was indeed great when further conversation showed me that the whole of the "Principles" were included in the "fads"!) Darwin himself possessed a copy of Playfair's "Illustrations of the Huttonian Theory", and occasionally quotes it; but I have met with only one reference to Hutton, and that a somewhat enigmatical one, in all Darwin's writings. In a letter to Lyell in 1841, when his mind was much exercised concerning glacial questions, he says "What a grand new feature all this ice work is in Geology! How old Hutton would have stared!" ("M.L." II. page 149.) As a consequence of the influences brought to bear on his mind during his two years' residence in Edinburgh, Darwin, who had entered that University with strong geological aspirations, left it and proceeded to Cambridge with a pronounced distaste for the whole subject. The result of this was that, during his career as an under-graduate, he neglected all the opportunities for geological study. During that important period of life, when he was between eighteen and twenty years of age, Darwin spent his time in riding, shooting and beetle-hunting, pursuits which were undoubtedly an admirable preparation for his future work as an explorer; but in none of his letters of this period does he even mention geology. He says, however, "I was so sickened with lectures at Edinburgh that I did not even attend Sedgwick's eloquent and interesting lectures." ("L.L." I. page 48.) It was only after passing his examination, and when he went up to spend two extra terms at Cambridge, that geology again began to attract his attention. The reading of Sir John Herschel's "Introduction to the Study of Natural Philosophy", and of Humboldt's "Personal Narrative", a copy of which last had been given to him by his good friend and mentor Henslow, roused his dormant enthusiasm for science, and awakened in his mind a passionate desire for travel. And it was from Henslow, whom he had accompanied in his excursions, but without imbibing any marked taste, at that time, for botany, that the advice came to think of and to "begin the study of geology." ("L.L." I. page 56.) This was in 1831, and in the summer vacation of that year we find him back again at Shrewsbury "working like a tiger" at geology and endeavouring to make a map and section of Shropshire--work which he says was not "as easy as I expected." ("L.L." I. page 189.) No better field for geological studies could possibly be found than Darwin's native county. Writing to Henslow at this time, and referring to a form of the instrument devised by his friend, Darwin says: "I am very glad to say I think the clinometer will answer admirably. I put all the tables in my bedroom at every conceivable angle and direction. I will venture to say that I have measured them as accurately as any geologist going could do." But he adds: "I have been working at so many things that I have not got on much with geology. I suspect the first expedition I take, clinometer and hammer in hand, will send me back very little wiser and a good deal more puzzled than when I started." ("L.L." I. page 189.) Valuable aid was, however, at hand, for at this time Sedgwick, to whom Darwin had been introduced by the ever-helpful Henslow, was making one of his expeditions into Wales, and consented to accept the young student as his companion during the geological tour. ("L.L." I. page 56.) We find Darwin looking forward to this privilege with the keenest interest. ("L.L." I. page 189.) When at the beginning of August (1831), Sedgwick arrived at his father's house in Shrewsbury, where he spent a night, Darwin began to receive his first and only instruction as a field-geologist. The journey they took together led them through Llangollen, Conway, Bangor, and Capel Curig, at which latter place they parted after spending many hours in examining the rocks at Cwm Idwal with extreme care, seeking for fossils but without success. Sedgwick's mode of instruction was admirable--he from time to time sent the pupil off on a line parallel to his own, "telling me to bring back specimens of the rocks and to mark the stratification on a map." ("L.L." I. page 57.) On his return to Shrewsbury, Darwin wrote to Henslow, "My trip with Sedgwick answered most perfectly," ("L.L." I. page 195.), and in the following year he wrote again from South America to the same friend, "Tell Professor Sedgwick he does not know how much I am indebted to him for the Welsh expedition; it has given me an interest in Geology which I would not give up for any consideration. I do not think I ever spent a more delightful three weeks than pounding the north-west mountains." ("L.L." I. pages 237-8.) It would be a mistake, however, to suppose that at this time Darwin had acquired anything like the affection for geological study, which he afterwards developed. After parting with Sedgwick, he walked in a straight line by compass and map across the mountains to Barmouth to visit a reading party there, but taking care to return to Shropshire before September 1st, in order to be ready for the shooting. For as he candidly tells us, "I should have thought myself mad to give up the first days of partridge-shooting for geology or any other science!" ("L.L." I. page 58.) Any regret we may be disposed to feel that Darwin did not use his opportunities at Edinburgh and Cambridge to obtain systematic and practical instruction in mineralogy and geology, will be mitigated, however, when we reflect on the danger which he would run of being indoctrinated with the crude "catastrophic" views of geology, which were at that time prevalent in all the centres of learning. Writing to Henslow in the summer of 1831, Darwin says "As yet I have only indulged in hypotheses, but they are such powerful ones that I suppose, if they were put into action but for one day, the world would come to an end." ("L.L." I. page 189.) May we not read in this passage an indication that the self-taught geologist had, even at this early stage, begun to feel a distrust for the prevalent catastrophism, and that his mind was becoming a field in which the seeds which Lyell was afterwards to sow would "fall on good ground"? The second period of Darwin's geological career--the five years spent by him on board the "Beagle"--was the one in which by far the most important stage in his mental development was accomplished. He left England a healthy, vigorous and enthusiastic collector; he returned five years later with unique experiences, the germs of great ideas, and a knowledge which placed him at once in the foremost ranks of the geologists of that day. Huxley has well said that "Darwin found on board the "Beagle" that which neither the pedagogues of Shrewsbury, nor the professoriate of Edinburgh, nor the tutors of Cambridge had managed to give him." ("Proc. Roy. Soc." Vol. XLIV. (1888), page IX.) Darwin himself wrote, referring to the date at which the voyage was expected to begin: "My second life will then commence, and it shall be as a birthday for the rest of my life." ("L.L." I. page 214.); and looking back on the voyage after forty years, he wrote; "The voyage of the 'Beagle' has been by far the most important event in my life, and has determined my whole career;... I have always felt that I owe to the voyage the first real training or education of my mind; I was led to attend closely to several branches of natural history, and thus my powers of observation were improved, though they were always fairly developed." ("L.L." I. page 61.) Referring to these general studies in natural history, however, Darwin adds a very significant remark: "The investigation of the geology of the places visited was far more important, as reasoning here comes into play. On first examining a new district nothing can appear more hopeless than the chaos of rocks; but by recording the stratification and nature of the rocks and fossils at many points, always reasoning and predicting what will be found elsewhere, light soon begins to dawn on the district, and the structure of the whole becomes more or less intelligible." ("L.L." I. page 62.) The famous voyage began amid doubts, discouragements and disappointments. Fearful of heart-disease, sad at parting from home and friends, depressed by sea-sickness, the young explorer, after being twice driven back by baffling winds, reached the great object of his ambition, the island of Teneriffe, only to find that, owing to quarantine regulations, landing was out of the question. But soon this inauspicious opening of the voyage was forgotten. Henslow had advised his pupil to take with him the first volume of Lyell's "Principles of Geology", then just published--but cautioned him (as nearly all the leaders in geological science at that day would certainly have done) "on no account to accept the views therein advocated." ("L.L." I. page 73.) It is probable that the days of waiting, discomfort and sea-sickness at the beginning of the voyage were relieved by the reading of this volume. For he says that when he landed, three weeks after setting sail from Plymouth, in St Jago, the largest of the Cape de Verde Islands, the volume had already been "studied attentively; and the book was of the highest service to me in many ways... " His first original geological work, he declares, "showed me clearly the wonderful superiority of Lyell's manner of treating geology, compared with that of any other author, whose works I had with me or ever afterwards read." ("L.L." I. page 62.) At St Jago Darwin first experienced the joy of making new discoveries, and his delight was unbounded. Writing to his father he says, "Geologising in a volcanic country is most delightful; besides the interest attached to itself, it leads you into most beautiful and retired spots." ("L.L." I. page 228.) To Henslow he wrote of St Jago: "Here we spent three most delightful weeks... St Jago is singularly barren, and produces few plants or insects, so that my hammer was my usual companion, and in its company most delightful hours I spent." "The geology was pre-eminently interesting, and I believe quite new; there are some facts on a large scale of upraised coast (which is an excellent epoch for all the volcanic rocks to date from), that would interest Mr Lyell." ("L.L." I. page 235.) After more than forty years the memory of this, his first geological work, seems as fresh as ever, and he wrote in 1876, "The geology of St Jago is very striking, yet simple: a stream of lava formerly flowed over the bed of the sea, formed of triturated recent shells and corals, which it has baked into a hard white rock. Since then the whole island has been upheaved. But the line of white rock revealed to me a new and important fact, namely, that there had been afterwards subsidence round the craters, which had since been in action, and had poured forth lava." ("L.L." I. page 65.) It was at this time, probably, that Darwin made his first attempt at drawing a sketch-map and section to illustrate the observations he had made (see his "Volcanic Islands", pages 1 and 9). His first important geological discovery, that of the subsidence of strata around volcanic vents (which has since been confirmed by Mr Heaphy in New Zealand and other authors) awakened an intense enthusiasm, and he writes: "It then first dawned on me that I might perhaps write a book on the geology of the various countries visited, and this made me thrill with delight. That was a memorable hour to me, and how distinctly I can call to mind the low cliff of lava beneath which I rested, with the sun glaring hot, a few strange desert plants growing near, and with living corals in the tidal pools at my feet." ("L.L." I. page 66.) But it was when the "Beagle", after touching at St Paul's rock and Tristan d'Acunha (for a sufficient time only to collect specimens), reached the shores of South America, that Darwin's real work began; and he was able, while the marine surveys were in progress, to make many extensive journeys on land. His letters at this time show that geology had become his chief delight, and such exclamations as "Geology carries the day," "I find in Geology a never failing interest," etc. abound in his correspondence. Darwin's time was divided between the study of the great deposits of red mud--the Pampean formation--with its interesting fossil bones and shells affording proofs of slow and constant movements of the land, and the underlying masses of metamorphic and plutonic rocks. Writing to Henslow in March, 1834, he says: "I am quite charmed with Geology, but, like the wise animal between two bundles of hay, I do not know which to like best; the old crystalline groups of rocks, or the softer and fossiliferous beds. When puzzling about stratification, etc., I feel inclined to cry 'a fig for your big oysters, and your bigger megatheriums.' But then when digging out some fine bones, I wonder how any man can tire his arms with hammering granite." ("L.L." I. page 249.) We are told by Darwin that he loved to reason about and attempt to predict the nature of the rocks in each new district before he arrived at it. This love of guessing as to the geology of a district he was about to visit is amusingly expressed by him in a letter (of May, 1832) to his cousin and old college-friend, Fox. After alluding to the beetles he had been collecting--a taste his friend had in common with himself--he writes of geology that "It is like the pleasure of gambling. Speculating on first arriving, what the rocks may be, I often mentally cry out 3 to 1 tertiary against primitive; but the latter have hitherto won all the bets." ("L.L." I. page 233.) Not the least important of the educational results of the voyage to Darwin was the acquirement by him of those habits of industry and method which enabled him in after life to accomplish so much--in spite of constant failures of health. From the outset, he daily undertook and resolutely accomplished, in spite of sea-sickness and other distractions, four important tasks. In the first place he regularly wrote up the pages of his Journal, in which, paying great attention to literary style and composition, he recorded only matters that would be of general interest, such as remarks on scenery and vegetation, on the peculiarities and habits of animals, and on the characters, avocations and political institutions of the various races of men with whom he was brought in contact. It was the freshness of these observations that gave his "Narrative" so much charm. Only in those cases in which his ideas had become fully crystallised, did he attempt to deal with scientific matters in this journal. His second task was to write in voluminous note-books facts concerning animals and plants, collected on sea or land, which could not be well made out from specimens preserved in spirit; but he tells us that, owing to want of skill in dissecting and drawing, much of the time spent in this work was entirely thrown away, "a great pile of MS. which I made during the voyage has proved almost useless." ("L.L." I. page 62.) Huxley confirmed this judgment on his biological work, declaring that "all his zeal and industry resulted, for the most part, in a vast accumulation of useless manuscript." ("Proc. Roy. Soc." Vol. XLIV. (1888), page IX.) Darwin's third task was of a very different character and of infinitely greater value. It consisted in writing notes of his journeys on land--the notes being devoted to the geology of the districts visited by him. These formed the basis, not only of a number of geological papers published on his return, but also of the three important volumes forming "The Geology of the voyage of the 'Beagle'". On July 24th, 1834, when little more than half of the voyage had been completed, Darwin wrote to Henslow, "My notes are becoming bulky. I have about 600 small quarto pages full; about half of this is Geology." ("M.L." I. page 14.) The last, and certainly not the least important of all his duties, consisted in numbering, cataloguing, and packing his specimens for despatch to Henslow, who had undertaken the care of them. In his letters he often expresses the greatest solicitude lest the value of these specimens should be impaired by the removal of the numbers corresponding to his manuscript lists. Science owes much to Henslow's patient care of the collections sent to him by Darwin. The latter wrote in Henslow's biography, "During the five years' voyage, he regularly corresponded with me and guided my efforts; he received, opened, and took care of all the specimens sent home in many large boxes." ("Life of Henslow", by L. Jenyns (Blomefield), London, 1862, page 53.) Darwin's geological specimens are now very appropriately lodged for the most part in the Sedgwick Museum, Cambridge, his original Catalogue with subsequent annotations being preserved with them. From an examination of these catalogues and specimens we are able to form a fair notion of the work done by Darwin in his little cabin in the "Beagle", in the intervals between his land journeys. Besides writing up his notes, it is evident that he was able to accomplish a considerable amount of study of his specimens, before they were packed up for despatch to Henslow. Besides hand-magnifiers and a microscope, Darwin had an equipment for blowpipe-analysis, a contact-goniometer and magnet; and these were in constant use by him. His small library of reference (now included in the Collection of books placed by Mr F. Darwin in the Botany School at Cambridge ("Catalogue of the Library of Charles Darwin now in the Botany School, Cambridge". Compiled by H.W. Rutherford; with an introduction by Francis Darwin. Cambridge, 1908.)) appears to have been admirably selected, and in all probability contained (in addition to a good many works relating to South America) a fair number of excellent books of reference. Among those relating to mineralogy, he possessed the manuals of Phillips, Alexander Brongniart, Beudant, von Kobell and Jameson: all the "Cristallographie" of Brochant de Villers and, for blowpipe work, Dr Children's translation of the book of Berzelius on the subject. In addition to these, he had Henry's "Experimental Chemistry" and Ure's "Dictionary" (of Chemistry). A work, he evidently often employed, was P. Syme's book on "Werner's Nomenclature of Colours"; while, for Petrology, he used Macculloch's "Geological Classification of Rocks". How diligently and well he employed his instruments and books is shown by the valuable observations recorded in the annotated Catalogues drawn up on board ship. These catalogues have on the right-hand pages numbers and descriptions of the specimens, and on the opposite pages notes on the specimens--the result of experiments made at the time and written in a very small hand. Of the subsequently made pencil notes, I shall have to speak later. (I am greatly indebted to my friend Mr A. Harker, F.R.S., for his assistance in examining these specimens and catalogues. He has also arranged the specimens in the Sedgwick Museum, so as to make reference to them easy. The specimens from Ascension and a few others are however in the Museum at Jermyn Street.) It is a question of great interest to determine the period and the occasion of Darwin's first awakening to the great problem of the transmutation of species. He tells us himself that his grandfather's "Zoonomia" had been read by him "but without producing any effect," and that his friend Grant's rhapsodies on Lamarck and his views on evolution only gave rise to "astonishment." ("L.L." I. page 38.) Huxley, who had probably never seen the privately printed volume of letters to Henslow, expressed the opinion that Darwin could not have perceived the important bearing of his discovery of bones in the Pampean Formation, until they had been studied in England, and their analogies pronounced upon by competent comparative anatomists. And this seemed to be confirmed by Darwin's own entry in his pocket-book for 1837, "In July opened first notebook on Transmutation of Species. Had been greatly struck from about the month of previous March on character of South American fossils... " ("L.L." I. page 276.) The second volume of Lyell's "Principles of Geology" was published in January, 1832, and Darwin's copy (like that of the other two volumes, in a sadly dilapidated condition from constant use) has in it the inscription, "Charles Darwin, Monte Video. Nov. 1832." As everyone knows, Darwin in dedicating the second edition of his Journal of the Voyage to Lyell declared, "the chief part of whatever scientific merit this journal and the other works of the author may possess, has been derived from studying the well-known and admirable 'Principles of Geology'". In the first chapter of this second volume of the "Principles", Lyell insists on the importance of the species question to the geologist, but goes on to point out the difficulty of accepting the only serious attempt at a transmutation theory which had up to that time appeared--that of Lamarck. In subsequent chapters he discusses the questions of the modification and variability of species, of hybridity, and of the geographical distribution of plants and animals. He then gives vivid pictures of the struggle for existence, ever going on between various species, and of the causes which lead to their extinction--not by overwhelming catastrophes, but by the silent and almost unobserved action of natural causes. This leads him to consider theories with regard to the introduction of new species, and, rejecting the fanciful notions of "centres or foci of creation," he argues strongly in favour of the view, as most reconcileable with observed facts, that "each species may have had its origin in a single pair, or individual, where an individual was sufficient, and species may have been created in succession at such times and in such places as to enable them to multiply and endure for an appointed period, and occupy an appointed space on the globe." ("Principles of Geology", Vol. II. (1st edition 1832), page 124. We now know, as has been so well pointed out by Huxley, that Lyell, as early as 1827, was prepared to accept the doctrine of the transmutation of species. In that year he wrote to Mantell, "What changes species may really undergo! How impossible will it be to distinguish and lay down a line, beyond which some of the so-called extinct species may have never passed into recent ones" (Lyell's "Life and Letters" Vol. I. page 168). To Sir John Herschel in 1836, he wrote, "In regard to the origination of new species, I am very glad to find that you think it probable that it may be carried on through the intervention of intermediate causes. I left this rather to be inferred, not thinking it worth while to offend a certain class of persons by embodying in words what would only be a speculation" (Ibid. page 467). He expressed the same views to Whewell in 1837 (Ibid. Vol. II. page 5.), and to Sedgwick (Ibid. Vol. II. page 36) to whom he says, of "the theory, that the creation of new species is going on at the present day"--"I really entertain it," but "I have studiously avoided laying the doctrine down dogmatically as capable of proof" (see Huxley in "L.L." II. pages 190-195.)) After pointing out how impossible it would be for a naturalist to prove that a newly DISCOVERED species was really newly CREATED (Mr F. Darwin has pointed out that his father (like Lyell) often used the term "Creation" in speaking of the origin of new species ("L.L." II. chapter 1.)), Lyell argued that no satisfactory evidence OF THE WAY in which these new forms were created, had as yet been discovered, but that he entertained the hope of a possible solution of the problem being found in the study of the geological record. It is not difficult, in reading these chapters of Lyell's great work, to realise what an effect they would have on the mind of Darwin, as new facts were collected and fresh observations concerning extinct and recent forms were made in his travels. We are not surprised to find him writing home, "I am become a zealous disciple of Mr Lyell's views, as known in his admirable book. Geologising in South America, I am tempted to carry parts to a greater extent even than he does." ("L.L." I. page 263.) Lyell's anticipation that the study of the geological record might afford a clue to the discovery of how new species originate was remarkably fulfilled, within a few months, by Darwin's discovery of fossil bones in the red Pampean mud. It is very true that, as Huxley remarked, Darwin's knowledge of comparative anatomy must have been, at that time, slight; but that he recognised the remarkable resemblances between the extinct and existing mammals of South America is proved beyond all question by a passage in his letter to Henslow, written November 24th, 1832: "I have been very lucky with fossil bones; I have fragments of at least six distinct animals... I found a large surface of osseous polygonal plates... Immediately I saw them I thought they must belong to an enormous armadillo, living species of which genus are so abundant here," and he goes on to say that he has "the lower jaw of some large animal which, from the molar teeth, I should think belonged to the Edentata." ("M.L." I. pages 11, 12. See "Extracts of Letters addressed to Prof. Henslow by C. Darwin" (1835), page 7.) Having found this important clue, Darwin followed it up with characteristic perseverance. In his quest for more fossil bones he was indefatigable. Mr Francis Darwin tells us, "I have often heard him speak of the despair with which he had to break off the projecting extremity of a huge, partly excavated bone, when the boat waiting for him would wait no longer." ("L.L." I. page 276 (footnote).) Writing to Haeckel in 1864, Darwin says: "I shall never forget my astonishment when I dug out a gigantic piece of armour, like that of the living armadillo." (Haeckel, "History of Creation", Vol. I. page 134, London, 1876.) In a letter to Henslow in 1834 Darwin says: "I have just got scent of some fossil bones... what they may be I do not know, but if gold or galloping will get them they shall be mine." ("M.L." I. page 15.) Darwin also showed his sense of the importance of the discovery of these bones by his solicitude about their safe arrival and custody. From the Falkland Isles (March, 1834), he writes to Henslow: "I have been alarmed by your expression 'cleaning all the bones' as I am afraid the printed numbers will be lost: the reason I am so anxious they should not be, is, that a part were found in a gravel with recent shells, but others in a very different bed. Now with these latter there were bones of an Agouti, a genus of animals, I believe, peculiar to America, and it would be curious to prove that some one of the genus co-existed with the Megatherium: such and many other points depend on the numbers being carefully preserved." ("Extracts from Letters etc.", pages 13-14.) In the abstract of the notes read to the Geological Society in 1835, we read: "In the gravel of Patagonia he (Darwin) also found many bones of the Megatherium and of five or six other species of quadrupeds, among which he has detected the bones of a species of Agouti. He also met with several examples of the polygonal plates, etc." ("Proc. Geol. Soc." Vol. II. pages 211-212.) Darwin's own recollections entirely bear out the conclusion that he fully recognised, WHILE IN SOUTH AMERICA, the wonderful significance of the resemblances between the extinct and recent mammalian faunas. He wrote in his "Autobiography": "During the voyage of the 'Beagle' I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos." ("L.L." I. page 82.) The impression made on Darwin's mind by the discovery of these fossil bones, was doubtless deepened as, in his progress southward from Brazil to Patagonia, he found similar species of Edentate animals everywhere replacing one another among the living forms, while, whenever fossils occurred, they also were seen to belong to the same remarkable group of animals. (While Darwin was making these observations in South America, a similar generalisation to that at which he arrived was being reached, quite independently and almost simultaneously, with respect to the fossil and recent mammals of Australia. In the year 1831, Clift gave to Jameson a list of bones occurring in the caves and breccias of Australia, and in publishing this list the latter referred to the fact that the forms belonged to marsupials, similar to those of the existing Australian fauna. But he also stated that, as a skull had been identified (doubtless erroneously) as having belonged to a hippopotamus, other mammals than marsupials must have spread over the island in late Tertiary times. It is not necessary to point out that this paper was quite unknown to Darwin while in South America. Lyell first noticed it in the third edition of his "Principles", which was published in May, 1834 (see "Edinb. New Phil. Journ." Vol. X. (1831), pages 394-6, and Lyell's "Principles" (3rd edition), Vol. III. page 421). Darwin referred to this discovery in 1839 (see his "Journal", page 210.)) That the passage in Darwin's pocket-book for 1837 can only refer to an AWAKENING of Darwin's interest in the subject--probably resulting from a sight of the bones when they were being unpacked--I think there cannot be the smallest doubt; AND WE MAY THEREFORE CONFIDENTLY FIX UPON NOVEMBER, 1832, AS THE DATE AT WHICH DARWIN COMMENCED THAT LONG SERIES OF OBSERVATIONS AND REASONINGS WHICH EVENTUALLY CULMINATED IN THE PREPARATION OF THE "ORIGIN OF SPECIES". Equally certain is it, that it was his geological work that led Darwin into those paths of research which in the end conducted him to his great discoveries. I quite agree with the view expressed by Mr F. Darwin and Professor Seward, that Darwin, like Lyell, "thought it 'almost useless' to try to prove the truth of evolution until the cause of change was discovered" ("M.L." I. page 38.), and that possibly he may at times have vacillated in his opinions, but I believe there is evidence that, from the date mentioned, the "species question" was always more or less present in Darwin's mind. (Although we admit with Huxley that Darwin's training in comparative anatomy was very small, yet it may be remembered that he was a medical student for two years, and, if he hated the lectures, he enjoyed the society of naturalists. He had with him in the little "Beagle" library a fair number of zoological books, including works on Osteology by Cuvier, Desmarest and Lesson, as well as two French Encyclopaedias of Natural History. As a sportsman, he would obtain specimens of recent mammals in South America, and would thus have opportunities of studying their teeth and general anatomy. Keen observer, as he undoubtedly was, we need not then be surprised that he was able to make out the resemblances between the recent and fossil forms.) It is clear that, as time went on, Darwin became more and more absorbed in his geological work. One very significant fact was that the once ardent sportsman, when he found that shooting the necessary game and zoological specimens interfered with his work with the hammer, gave up his gun to his servant. ("L.L." I. page 63.) There is clear evidence that Darwin gradually became aware how futile were his attempts to add to zoological knowledge by dissection and drawing, while he felt ever increasing satisfaction with his geological work. The voyage fortunately extended to a much longer period (five years) than the two originally intended, but after being absent nearly three years, Darwin wrote to his sister in November, 1834, "Hurrah! hurrah! it is fixed that the 'Beagle' shall not go one mile south of Cape Tres Montes (about 200 miles south of Chiloe), and from that point to Valparaiso will be finished in about five months. We shall examine the Chonos Archipelago, entirely unknown, and the curious inland sea behind Chiloe. For me it is glorious. Cape Tres Montes is the most southern point where there is much geological interest, as there the modern beds end. The Captain then talks of crossing the Pacific; but I think we shall persuade him to finish the coast of Peru, where the climate is delightful, the country hideously sterile, but abounding with the highest interest to the geologist... I have long been grieved and most sorry at the interminable length of the voyage (though I never would have quitted it)... I could not make up my mind to return. I could not give up all the geological castles in the air I had been building up for the last two years." ("L.L." I. pages 257-58.) In April, 1835, he wrote to another sister: "I returned a week ago from my excursion across the Andes to Mendoza. Since leaving England I have never made so successful a journey... how deeply I have enjoyed it; it was something more than enjoyment; I cannot express the delight which I felt at such a famous winding-up of all my geology in South America. I literally could hardly sleep at nights for thinking over my day's work. The scenery was so new, and so majestic; everything at an elevation of 12,000 feet bears so different an aspect from that in the lower country... To a geologist, also, there are such manifest proofs of excessive violence; the strata of the highest pinnacles are tossed about like the crust of a broken pie." ("L.L." I. pages 259-60.) Darwin anticipated with intense pleasure his visit to the Galapagos Islands. On July 12th, 1835, he wrote to Henslow: "In a few days' time the "Beagle" will sail for the Galapagos Islands. I look forward with joy and interest to this, both as being somewhat nearer to England and for the sake of having a good look at an active volcano. Although we have seen lava in abundance, I have never yet beheld the crater." ("M.L." I. page 26.) He could little anticipate, as he wrote these lines, the important aid in the solution of the "species question" that would ever after make his visit to the Galapagos Islands so memorable. In 1832, as we have seen, the great discovery of the relations of living to extinct mammals in the same area had dawned upon his mind; in 1835 he was to find a second key for opening up the great mystery, by recognising the variations of similar types in adjoining islands among the Galapagos. The final chapter in the second volume of the "Principles" had aroused in Darwin's mind a desire to study coral-reefs, which was gratified during his voyage across the Pacific and Indian Oceans. His theory on the subject was suggested about the end of 1834 or the beginning of 1835, as he himself tells us, before he had seen a coral-reef, and resulted from his work during two years in which he had "been incessantly attending to the effects on the shores of South America of the intermittent elevation of the land, together with denudation and the deposition of sediment." ("L.L." I. page 70.) On arriving at the Cape of Good Hope in July, 1836, Darwin was greatly gratified by hearing that Sedgwick had spoken to his father in high terms of praise concerning the work done by him in South America. Referring to the news from home, when he reached Bahia once more, on the return voyage (August, 1836), he says: "The desert, volcanic rocks, and wild sea of Ascension... suddenly wore a pleasing aspect, and I set to work with a good-will at my old work of Geology." ("L.L." I. page 265.) Writing fifty years later, he says: "I clambered over the mountains of Ascension with a bounding step and made the volcanic rocks resound under my geological hammer!" ("L.L." I. page 66.) That his determination was now fixed to devote his own labours to the task of working out the geological results of the voyage, and that he was prepared to leave to more practised hands the study of his biological collections, is clear from the letters he sent home at this time. From St Helena he wrote to Henslow asking that he would propose him as a Fellow of the Geological Society; and his Certificate, in Henslow's handwriting, is dated September 8th, 1836, being signed from personal knowledge by Henslow and Sedgwick. He was proposed on November 2nd and elected November 30th, being formally admitted to the Society by Lyell, who was then President, on January 4th, 1837, on which date he also read his first paper. Darwin did not become a Fellow of the Linnean Society till eighteen years later (in 1854). An estimate of the value and importance of Darwin's geological discoveries during the voyage of the "Beagle" can best be made when considering the various memoirs and books in which the author described them. He was too cautious to allow himself to write his first impressions in his Journal, and wisely waited till he could study his specimens under better conditions and with help from others on his return. The extracts published from his correspondence with Henslow and others, while he was still abroad, showed, nevertheless, how great was the mass of observation, how suggestive and pregnant with results were the reasonings of the young geologist. Two sets of these extracts from Darwin's letters to Henslow were printed while he was still abroad. The first of these was the series of "Geological Notes made during a survey of the East and West Coasts of South America, in the years 1832, 1833, 1834 and 1835, with an account of a transverse section of the Cordilleras of the Andes between Valparaiso and Mendoza". Professor Sedgwick, who read these notes to the Geological Society on November 18th, 1835, stated that "they were extracted from a series of letters (addressed to Professor Henslow), containing a great mass of information connected with almost every branch of natural history," and that he (Sedgwick) had made a selection of the remarks which he thought would be more especially interesting to the Geological Society. An abstract of three pages was published in the "Proceedings of the Geological Society" (Vol. II. pages 210-12.), but so unknown was the author at this time that he was described as F. Darwin, Esq., of St John's College, Cambridge! Almost simultaneously (on November 16th, 1835) a second set of extracts from these letters--this time of a general character--were read to the Philosophical Society at Cambridge, and these excited so much interest that they were privately printed in pamphlet form for circulation among the members. Many expeditions and "scientific missions" have been despatched to various parts of the world since the return of the "Beagle" in 1836, but it is doubtful whether any, even the most richly endowed of them, has brought back such stores of new information and fresh discoveries as did that little "ten-gun brig"--certainly no cabin or laboratory was the birth-place of ideas of such fruitful character as was that narrow end of a chart-room, where the solitary naturalist could climb into his hammock and indulge in meditation. The third and most active portion of Darwin's career as a geologist was the period which followed his return to England at the end of 1836. His immediate admission to the Geological Society, at the beginning of 1837, coincided with an important crisis in the history of geological science. The band of enthusiasts who nearly thirty years before had inaugurated the Geological Society--weary of the fruitless conflicts between "Neptunists" and "Plutonists"--had determined to eschew theory and confine their labours to the collection of facts, their publications to the careful record of observations. Greenough, the actual founder of the Society, was an ardent Wernerian, and nearly all his fellow-workers had come, more or less directly, under the Wernerian teaching. Macculloch alone gave valuable support to the Huttonian doctrines, so far as they related to the influence of igneous activity--but the most important portion of the now celebrated "Theory of the Earth"--that dealing with the competency of existing agencies to account for changes in past geological times--was ignored by all alike. Macculloch's influence on the development of geology, which might have had far-reaching effects, was to a great extent neutralised by his peculiarities of mind and temper; and, after a stormy and troublous career, he retired from the society in 1832. In all the writings of the great pioneers in English geology, Hutton and his splendid generalisation are scarcely ever referred to. The great doctrines of Uniformitarianism, which he had foreshadowed, were completely ignored, and only his extravagances of "anti-Wernerianism" seem to have been remembered. When between 1830 and 1832, Lyell, taking up the almost forgotten ideas of Hutton, von Hoff and Prevost, published that bold challenge to the Catastrophists--the "Principles of Geology"--he was met with the strongest opposition, not only from the outside world, which was amused by his "absurdities" and shocked by his "impiety"--but not less from his fellow-workers and friends in the Geological Society. For Lyell's numerous original observations, and his diligent collection of facts his contemporaries had nothing but admiration, and they cheerfully admitted him to the highest offices in the society, but they met his reasonings on geological theory with vehement opposition and his conclusions with coldness and contempt. There is, indeed, a very striking parallelism between the reception of the "Principles of Geology" by Lyell's contemporaries and the manner in which the "Origin of Species" was met a quarter of a century later, as is so vividly described by Huxley. ("L.L." II. pages 179-204.) Among Lyell's fellow-geologists, two only--G. Poulett Scrope and John Herschel (Both Lyell and Darwin fully realised the value of the support of these two friends. Scrope in his appreciative reviews of the "Principles" justly pointed out what was the weakest point, the inadequate recognition of sub-aerial as compared with marine denudation. Darwin also admitted that Scrope had to a great extent forestalled him in his theory of Foliation. Herschel from the first insisted that the leading idea of the "Principles" must be applied to organic as well as to inorganic nature and must explain the appearance of new species (see Lyell's "Life and Letters", Vol. I. page 467). Darwin tells us that Herschel's "Introduction to the Study of Natural Philosophy" with Humboldt's "Personal Narrative" "stirred up in me a burning zeal" in his undergraduate days. I once heard Lyell exclaim with fervour "If ever there was a heaven-born genius it was John Herschel!")--declared themselves from the first his strong supporters. Scrope in two luminous articles in the "Quarterly Review" did for Lyell what Huxley accomplished for Darwin in his famous review in the "Times"; but Scrope unfortunately was at that time immersed in the stormy sea of politics, and devoted his great powers of exposition to the preparation of fugitive pamphlets. Herschel, like Scrope, was unable to support Lyell at the Geological Society, owing to his absence on the important astronomical mission to the Cape. It thus came about that, in the frequent conflicts of opinion within the walls of the Geological Society, Lyell had to bear the brunt of battle for Uniformitarianism quite alone, and it is to be feared that he found himself sadly overmatched when opposed by the eloquence of Sedgwick, the sarcasm of Buckland, and the dead weight of incredulity on the part of Greenough, Conybeare, Murchison and other members of the band of pioneer workers. As time went on there is evidence that the opposition of De la Beche and Whewell somewhat relaxed; the brilliant "Paddy" Fitton (as his friends called him) was sometimes found in alliance with Lyell, but was characteristically apt to turn his weapon, as occasion served, on friend or foe alike; the amiable John Phillips "sat upon the fence." Only when a new generation arose--including Jukes, Ramsay, Forbes and Hooker--did Lyell find his teachings received with anything like favour. We can well understand, then, how Lyell would welcome such a recruit as young Darwin--a man who had declared himself more Lyellian than Lyell, and who brought to his support facts and observations gleaned from so wide a field. The first meeting of Lyell and Darwin was characteristic of the two men. Darwin at once explained to Lyell that, with respect to the origin of coral-reefs, he had arrived at views directly opposed to those published by "his master." To give up his own theory, cost Lyell, as he told Herschel, a "pang at first," but he was at once convinced of the immeasurable superiority of Darwin's theory. I have heard members of Lyell's family tell of the state of wild excitement and sustained enthusiasm, which lasted for days with Lyell after this interview, and his letters to Herschel, Whewell and others show his pleasure at the new light thrown upon the subject and his impatience to have the matter laid before the Geological Society. Writing forty years afterwards, Darwin, speaking of the time of the return of the "Beagle", says: "I saw a great deal of Lyell. One of his chief characteristics was his sympathy with the work of others, and I was as much astonished as delighted at the interest which he showed when, on my return to England, I explained to him my views on coral-reefs. This encouraged me greatly, and his advice and example had much influence on me." ("L.L." I. page 68.) Darwin further states that he saw more of Lyell at this time than of any other scientific man, and at his request sent his first communication to the Geological Society. ("L.L." I. page 67.) "Mr Lonsdale" (the able curator of the Geological Society), Darwin wrote to Henslow, "with whom I had much interesting conversation," "gave me a most cordial reception," and he adds, "If I was not much more inclined for geology than the other branches of Natural History, I am sure Mr Lyell's and Lonsdale's kindness ought to fix me. You cannot conceive anything more thoroughly good-natured than the heart-and-soul manner in which he put himself in my place and thought what would be best to do." ("L.L." I. page 275.) Within a few days of Darwin's arrival in London we find Lyell writing to Owen as follows: "Mrs Lyell and I expect a few friends here on Saturday next, 29th (October), to an early tea party at eight o'clock, and it will give us great pleasure if you can join it. Among others you will meet Mr Charles Darwin, whom I believe you have seen, just returned from South America, where he has laboured for zoologists as well as for hammer-bearers. I have also asked your friend Broderip." ("The Life of Richard Owen", London, 1894, Vol. I. page 102.) It would probably be on this occasion that the services of Owen were secured for the work on the fossil bones sent home by Darwin. On November 2nd, we find Lyell introducing Darwin as his guest at the Geological Society Club; on December 14th, Lyell and Stokes proposed Darwin as a member of the Club; between that date and May 3rd of the following year, when his election to the Club took place, he was several times dining as a guest. On January 4th, 1837, as we have already seen, Darwin was formally admitted to the Geological Society, and on the same evening he read his first paper (I have already pointed out that the notes read at the Geological Society on Nov. 18, 1835 were extracts made by Sedgwick from letters sent to Henslow, and not a paper sent home for publication by Darwin.) before the Society, "Observations of proofs of recent elevation on the coast of Chili, made during the Survey of H.M.S. "Beagle", commanded by Captain FitzRoy, R.N." By C. Darwin, F.G.S. This paper was preceded by one on the same subject by Mr A. Caldcleugh, and the reading of a letter and other communications from the Foreign Office also relating to the earthquakes in Chili. At the meeting of the Council of the Geological Society on February 1st, Darwin was nominated as a member of the new Council, and he was elected on February 17th. The meeting of the Geological Society on April 19th was devoted to the reading by Owen of his paper on Toxodon, perhaps the most remarkable of the fossil mammals found by Darwin in South America; and at the next meeting, on May 3rd, Darwin himself read "A Sketch of the Deposits containing extinct Mammalia in the neighbourhood of the Plata". The next following meeting, on May 17th, was devoted to Darwin's Coral-reef paper, entitled "On certain areas of elevation and subsidence in the Pacific and Indian Oceans, as deduced from the study of Coral Formations". Neither of these three early papers of Darwin were published in the Transactions of the Geological Society, but the minutes of the Council show that they were "withdrawn by the author by permission of the Council." Darwin's activity during this session led to some rather alarming effects upon his health, and he was induced to take a holiday in Staffordshire and the Isle of Wight. He was not idle, however, for a remark of his uncle, Mr Wedgwood, led him to make those interesting observations on the work done by earthworms, that resulted in his preparing a short memoir on the subject, and this paper, "On the Formation of Mould", was read at the Society on November 1st, 1837, being the first of Darwin's papers published in full; it appeared in Vol. V. of the "Geological Transactions", pages 505-510. During this session, Darwin attended nearly all the Council meetings, and took such an active part in the work of the Society that it is not surprising to find that he was now requested to accept the position of Secretary. After some hesitation, in which he urged his inexperience and want of knowledge of foreign languages, he consented to accept the appointment. ("L.L." I. page 285.) At the anniversary meeting on February 16th, 1838, the Wollaston Medal was given to Owen in recognition of his services in describing the fossil mammals sent home by Darwin. In his address, the President, Professor Whewell, dwelt at length on the great value of the papers which Darwin had laid before the Society during the preceding session. On March 7th, Darwin read before the Society the most important perhaps of all his geological papers, "On the Connexion of certain Volcanic Phenomena in South America, and on the Formation of Mountain-Chains and Volcanoes as the effect of Continental Elevations". In this paper he boldly attacked the tenets of the Catastrophists. It is evident that Darwin at this time, taking advantage of the temporary improvement in his health, was throwing himself into the breach of Uniformitarianism with the greatest ardour. Lyell wrote to Sedgwick on April 21st, 1837, "Darwin is a glorious addition to any society of geologists, and is working hard and making way, both in his book and in our discussions." ("The Life and Letters of the Reverend Adam Sedgwick", Vol. I. page 484, Cambridge, 1890.) We have unfortunately few records of the animated debates which took place at this time between the old and new schools of geologists. I have often heard Lyell tell how Lockhart would bring down a party of friends from the Athenaeum Club to Somerset House on Geological nights, not, as he carefully explained, that "he cared for geology, but because he liked to while the fellows fight." But it fortunately happens that a few days after this last of Darwin's great field-days, at the Geological Society, Lyell, in a friendly letter to his father-in-law, Leonard Horner, wrote a very lively account of the proceedings while his impressions were still fresh; and this gives us an excellent idea of the character of these discussions. Neither Sedgwick nor Buckland were present on this occasion, but we can imagine how they would have chastised their two "erring pupils"--more in sorrow than in anger--had they been there. Greenough, too, was absent--possibly unwilling to countenance even by his presence such outrageous doctrines. Darwin, after describing the great earthquakes which he had experienced in South America, and the evidence of their connection with volcanic outbursts, proceeded to show that earthquakes originated in fractures, gradually formed in the earth's crust, and were accompanied by movements of the land on either side of the fracture. In conclusion he boldly advanced the view "that continental elevations, and the action of volcanoes, are phenomena now in progress, caused by some great but slow change in the interior of the earth; and, therefore, that it might be anticipated, that the formation of mountain chains is likewise in progress: and at a rate which may be judged of by either actions, but most clearly by the growth of volcanoes." ("Proc. Geol. Soc." Vol. II. pages 654-60.) Lyell's account ("Life, Letters and Journals of Sir Charles Lyell, Bart.", edited by his sister-in-law, Mrs Lyell, Vol. II. pages 40, 41 (Letter to Leonard Horner, 1838), 2 vols. London, 1881.) of the discussion was as follows: "In support of my heretical notions," Darwin "opened upon De la Beche, Phillips and others his whole battery of the earthquakes and volcanoes of the Andes, and argued that spaces at least a thousand miles long were simultaneously subject to earthquakes and volcanic eruptions, and that the elevation of the Pampas, Patagonia, etc., all depended on a common cause; also that the greater the contortions of strata in a mountain chain, the smaller must have been each separate and individual movement of that long series which was necessary to upheave the chain. Had they been more violent, he contended that the subterraneous fluid matter would have gushed out and overflowed, and the strata would have been blown up and annihilated. (It is interesting to compare this with what Darwin wrote to Henslow seven years earlier.) He therefore introduces a cooling of one small underground injection, and then the pumping in of other lava, or porphyry, or granite, into the previously consolidated and first-formed mass of igneous rock. (Ideas somewhat similar to this suggestion have recently been revived by Dr See ("Proc. Am. Phil. Soc." Vol. XLVII. 1908, page 262.).) When he had done his description of the reiterated strokes of his volcanic pump, De la Beche gave us a long oration about the impossibility of strata of the Alps, etc., remaining flexible for such a time as they must have done, if they were to be tilted, convoluted, or overturned by gradual small shoves. He never, however, explained his theory of original flexibility, and therefore I am as unable as ever to comprehend why flexiblility is a quality so limited in time. "Phillips then got up and pronounced a panegyric upon the "Principles of Geology", and although he still differed, thought the actual cause doctrine had been so well put, that it had advanced the science and formed a date or era, and that for centuries the two opposite doctrines would divide geologists, some contending for greater pristine forces, others satisfied, like Lyell and Darwin, with the same intensity as nature now employs. "Fitton quizzed Phillips a little for the warmth of his eulogy, saying that he (Fitton) and others, who had Mr Lyell always with them, were in the habit of admiring and quarrelling with him every day, as one might do with a sister or cousin, whom one would only kiss and embrace fervently after a long absence. This seemed to be Mr Phillips' case, coming up occasionally from the provinces. Fitton then finished this drollery by charging me with not having done justice to Hutton, who he said was for gradual elevation. "I replied, that most of the critics had attacked me for overrating Hutton, and that Playfair understood him as I did. "Whewell concluded by considering Hopkins' mathematical calculations, to which Darwin had often referred. He also said that we ought not to try and make out what Hutton would have taught and thought, if he had known the facts which we now know." It may be necessary to point out, in explanation of the above narrative, that while it was perfectly clear from Hutton's rather obscure and involved writings that he advocated slow and gradual change on the earth's surface, his frequent references to violent action and earthquakes led many--including Playfair, Lyell and Whewell--to believe that he held the changes going on in the earth's interior to be of a catastrophic nature. Fitton, however, maintained that Hutton was consistently uniformitarian. Before the idea of the actual "flowing" of solid bodies under intense pressure had been grasped by geologists, De la Beche, like Playfair before him, maintained that the bending and folding of rocks must have been effected before their complete consolidation. In concluding his account of this memorable discussion, Lyell adds: "I was much struck with the different tone in which my gradual causes was treated by all, even including De la Beche, from that which they experienced in the same room four years ago, when Buckland, De la Beche(?), Sedgwick, Whewell, and some others treated them with as much ridicule as was consistent with politeness in my presence." This important paper was, in spite of its theoretical character, published in full in the "Transactions of the Geological Society" (Ser. 2, Vol. V. pages 601-630). It did not however appear till 1840, and possibly some changes may have been made in it during the long interval between reading and printing. During the year 1839, Darwin continued his regular attendance at the Council meetings, but there is no record of any discussions in which he may have taken part, and he contributed no papers himself to the Society. At the beginning of 1840, he was re-elected for the third time as Secretary, but the results of failing health are indicated by the circumstance that, only at one meeting early in the session, was he able to attend the Council. At the beginning of the next session (Feb. 1841) Bunbury succeeded him as Secretary, Darwin still remaining on the Council. It may be regarded as a striking indication of the esteem in which he was held by his fellow geologists, that Darwin remained on the Council for 14 consecutive years down to 1849, though his attendances were in some years very few. In 1843 and 1844 he was a Vice-president, but after his retirement at the beginning of 1850, he never again accepted re-nomination. He continued, however, to contribute papers to the Society, as we shall see, down to the end of 1862. Although Darwin early became a member of the Geological Dining Club, it is to be feared that he scarcely found himself in a congenial atmosphere at those somewhat hilarious gatherings, where the hardy wielders of the hammer not only drank port--and plenty of it--but wound up their meal with a mixture of Scotch ale and soda water, a drink which, as reminiscent of the "field," was regarded as especially appropriate to geologists. Even after the meetings, which followed the dinners, they reassembled for suppers, at which geological dainties, like "pterodactyle pie" figured in the bill of fare, and fines of bumpers were inflicted on those who talked the "ologies." After being present at a fair number of meetings in 1837 and 1838, Darwin's attendances at the Club fell off to two in 1839, and by 1841 he had ceased to be a member. In a letter to Lyell on Dec. 2nd, 1841, Leonard Horner wrote that the day before "At the Council, I had the satisfaction of seeing Darwin again in his place and looking well. He tried the last evening meeting, but found it too much, but I hope before the end of the season he will find himself equal to that also. I hail Darwin's recovery as a vast gain to science." Darwin's probably last attendance, this time as a guest, was in 1851, when Horner again wrote to Lyell, "Charles Darwin was at the Geological Society's Club yesterday, where he had not been for ten years--remarkably well, and grown quite stout." ("Memoirs of Leonard Horner" (privately printed), Vol. II. pages 39 and 195.) It may be interesting to note that at the somewhat less lively dining Club--the Philosophical--in the founding of which his friends Lyell and Hooker had taken so active a part, Darwin found himself more at home, and he was a frequent attendant--in spite of his residence being at Down--from 1853 to 1864. He even made contributions on scientific questions after these dinners. In a letter to Hooker he states that he was deeply interested in the reforms of the Royal Society, which the Club was founded to promote. He says also that he had arranged to come to town every Club day "and then my head, I think, will allow me on an average to go to every other meeting. But it is grievous how often any change knocks me up." ("L.L." II. pages 42, 43.) Of the years 1837 and 1838 Darwin himself says they were "the most active ones which I ever spent, though I was occasionally unwell, and so lost some time... I also went a little into society." ("L.L." I. pages 67, 68.) But of the four years from 1839 to 1842 he has to confess sadly "I did less scientific work, though I worked as hard as I could, than during any other equal length of time in my life. This was owing to frequently recurring unwellness, and to one long and serious illness." ("L.L." I. page 69.) Darwin's work at the Geological Society did not by any means engage the whole of his energies, during the active years 1837 and 1838. In June of the latter year, leaving town in somewhat bad health, he found himself at Edinburgh again, and engaged in examining the Salisbury Craigs, in a very different spirit to that excited by Jameson's discourse. ("L.L." I. page 290.) Proceeding to the Highlands he then had eight days of hard work at the famous "Parallel Roads of Glen Roy", being favoured with glorious weather. He says of the writing of the paper on the subject--the only memoir contributed by Darwin to the Royal Society, to which he had been recently elected--that it was "one of the most difficult and instructive tasks I was ever engaged on." The paper extends to 40 quarto pages and is illustrated by two plates. Though it is full of the records of careful observation and acute reasoning, yet the theory of marine beaches which he propounded was, as he candidly admitted in after years ("M.L." II page 188.), altogether wrong. The alternative lake-theory he found himself unable to accept at the time, for he could not understand how barriers could be formed at successive levels across the valleys; and until the following year, when the existence of great glaciers in the district was proved by the researches of Agassiz, Buckland and others, the difficulty appeared to him an insuperable one. Although Darwin said of this paper in after years that it "was a great failure and I am ashamed of it"--yet he retained his interest in the question ever afterwards, and he says "my error has been a good lesson to me never to trust in science to the principle of exclusion." ("M.L." II. pages 171-93.) Although Darwin had not realised in 1838 that large parts of the British Islands had been occupied by great glaciers, he had by no means failed while in South America to recognise the importance of ice-action. His observations, as recorded in his Journal, on glaciers coming down to the sea-level, on the west coast of South America, in a latitude corresponding to a much lower one than that of the British Islands, profoundly interested geologists; and the same work contains many valuable notes on the boulders and unstratified beds in South America in which they were included. But in 1840 Agassiz read his startling paper on the evidence of the former existence of glaciers in the British Islands, and this was followed by Buckland's memoir on the same subject. On April 14, 1841, Darwin contributed to the Geological Society his important paper "On the Distribution of Erratic Boulders and the Contemporaneous Unstratified Deposits of South America", a paper full of suggestiveness for those studying the glacial deposits of this country. It was published in the "Transactions" in 1842. The description of traces of glacial action in North Wales, by Buckland, appears to have greatly excited the interest of Darwin. With Sedgwick he had, in 1831, worked at the stratigraphy of that district, but neither of them had noticed the very interesting surface features. ("L.L." I. page 58.) Darwin was able to make a journey to North Wales in June, 1842 (alas! it was his last effort in field-geology) and as a result he published his most able and convincing paper on the subject in the September number of the "Philosophical Magazine" for 1842. Thus the mystery of the bell-stone was at last solved and Darwin, writing many years afterwards, said "I felt the keenest delight when I first read of the action of icebergs in transporting boulders, and I gloried in the progress of Geology." ("L.L." I. page 41.) To the "Geographical Journal" he had sent in 1839 a note "On a Rock seen on an Iceberg in 16 deg S. Latitude." For the subject of ice-action, indeed, Darwin retained the greatest interest to the end of his life. ("M.L." II. pages 148-71.) In 1846, Darwin read two papers to the Geological Society "On the dust which falls on vessels in the Atlantic, and On the Geology of the Falkland Islands"; in 1848 he contributed a note on the transport of boulders from lower to higher levels; and in 1862 another note on the thickness of the Pampean formation, as shown by recent borings at Buenos Ayres. An account of the "British Fossil Lepadidae" read in 1850, was withdrawn by him. At the end of 1836 Darwin had settled himself in lodgings in Fitzwilliam Street, Cambridge, and devoted three months to the work of unpacking his specimens and studying his collection of rocks. The pencilled notes on the Manuscript Catalogue in the Sedgwick Museum enable us to realise his mode of work, and the diligence with which it was carried on. The letters M and H, indicate the assistance he received from time to time from Professor Miller, the crystallographer, and from his friend Henslow. Miller not only measured many of the crystals submitted to him, but evidently taught Darwin to use the reflecting goniometer himself with considerable success. The "book of measurements" in which the records were kept, appears to have been lost, but the pencilled notes in the catalogue show how thoroughly the work was done. The letter R attached to some of the numbers in the catalogue evidently refers to the fact that they were submitted to Mr Trenham Reeks (who analysed some of his specimens) at the Geological Survey quarters in Craig's Court. This was at a later date when Darwin was writing the "Volcanic Islands" and "South America". It was about the month of March, 1837, that Darwin completed this work upon his rocks, and also the unpacking and distribution of his fossil bones and other specimens. We have seen that November, 1832, must certainly be regarded as the date when he FIRST realised the important fact that the fossil mammals of the Pampean formation were all closely related to the existing forms in South America; while October, 1835, was, as undoubtedly, the date when the study of the birds and other forms of life in the several islands of the Galapagos Islands gave him his SECOND impulse towards abandoning the prevalent view of the immutability of species. When then in his pocket-book for 1837 Darwin wrote the often quoted passage: "In July opened first note-book on Transmutation of Species. Had been greatly struck from about the month of previous March on character of South American fossils, and species on Galapagos Archipelago. These facts (especially latter), origin of all my views" ("L.L." I. page 276.), it is clear that he must refer, not to his first inception of the idea of evolution, but to the flood of recollections, the reawakening of his interest in the subject, which could not fail to result from the sight of his specimens and the reference to his notes. Except during the summer vacation, when he was visiting his father and uncle, and with the latter making his first observations upon the work of earthworms, Darwin was busy with his arrangements for the publication of the five volumes of the "Zoology of the 'Beagle'" and in getting the necessary financial aid from the government for the preparation of the plates. He was at the same time preparing his "Journal" for publication. During the years 1837 to 1843, Darwin worked intermittently on the volumes of Zoology, all of which he edited, while he wrote introductions to those by Owen and Waterhouse and supplied notes to the others. Although Darwin says of his Journal that the preparation of the book "was not hard work, as my MS. Journal had been written with care." Yet from the time that he settled at 36, Great Marlborough Street in March, 1837, to the following November he was occupied with this book. He tells us that the account of his scientific observations was added at this time. The work was not published till March, 1839, when it appeared as the third volume of the "Narrative of the Surveying Voyages of H.M. Ships 'Adventure' and 'Beagle' between the years 1826 and 1836". The book was probably a long time in the press, for there are no less than 20 pages of addenda in small print. Even in this, its first form, the work is remarkable for its freshness and charm, and excited a great amount of attention and interest. In addition to matters treated of in greater detail in his other works, there are many geological notes of extreme value in this volume, such as his account of lightning tubes, of the organisms found in dust, and of the obsidian bombs of Australia. Having thus got out of hand a number of preliminary duties, Darwin was ready to set to work upon the three volumes which were designed by him to constitute "The Geology of the Voyage of the 'Beagle'". The first of these was to be on "The Structure and Distribution of Coral-reefs". He commenced the writing of the book on October 5, 1838, and the last proof was corrected on May 6, 1842. Allowing for the frequent interruptions through illness, Darwin estimated that it cost him twenty months of hard work. Darwin has related how his theory of Coral-reefs which was begun in a more "deductive spirit" than any of his other work, for in 1834 or 1835 it "was thought out on the west coast of South America, before I had seen a true coral-reef." ("L.L." I. page 70.) The final chapter in Lyell's second volume of the "Principles" was devoted to the subject of Coral-reefs, and a theory was suggested to account for the peculiar phenomena of "atolls." Darwin at once saw the difficulty of accepting the view that the numerous and diverse atolls all represent submerged volcanic craters. His own work had for two years been devoted to the evidence of land movements over great areas in South America, and thus he was led to announce his theory of subsidence to account for barrier and encircling reefs as well as atolls. Fortunately, during his voyage across the Pacific and Indian Oceans, in his visit to Australia and his twelve days' hard work at Keeling Island, he had opportunities for putting his theory to the test of observation. On his return to England, Darwin appears to have been greatly surprised at the amount of interest that his new theory excited. Urged by Lyell, he read to the Geological Society a paper on the subject, as we have seen, with as little delay as possible, but this paper was "withdrawn by permission of the Council." An abstract of three pages however appeared in the "Proceedings of the Geological Society". (Vol. II. pages 552-554 (May 31, 1837).) A full account of the observations and the theory was given in the "Journal" (1839) in the 40 pages devoted to Keeling Island in particular and to Coral formations generally. ("Journal" (1st edition), pages 439-69.) It will be readily understood what an amount of labour the book on Coral reefs cost Darwin when we reflect on the number of charts, sailing directions, narratives of voyages and other works which, with the friendly assistance of the authorities at the Admiralty, he had to consult before he could draw up his sketch of the nature and distribution of the reefs, and this was necessary before the theory, in all its important bearings, could be clearly enunciated. Very pleasing is it to read how Darwin, although arriving at a different conclusion to Lyell, shows, by quoting a very suggestive passage in the "Principles" (1st edition Vol. II. page 296.), how the latter only just missed the true solution. This passage is cited, both in the "Journal" and the volume on Coral-reefs. Lyell, as we have seen, received the new theory not merely ungrudgingly, but with the utmost enthusiasm. In 1849 Darwin was gratified by receiving the support of Dana, after his prolonged investigation in connection with the U.S. Exploring Expedition ("M.L." II. pages 226-8.), and in 1874 he prepared a second edition of his book, in which some objections which had been raised to the theory were answered. A third edition, edited by Professor Bonney, appeared in 1880, and a fourth (a reprint of the first edition, with introduction by myself) in 1890. Although Professor Semper, in his account of the Pelew Islands, had suggested difficulties in the acceptance of Darwin's theory, it was not till after the return of the "Challenger" expedition in 1875 that a rival theory was propounded, and somewhat heated discussions were raised as to the respective merits of the two theories. While geologists have, nearly without exception, strongly supported Darwin's views, the notes of dissent have come almost entirely from zoologists. At the height of the controversy unfounded charges of unfairness were made against Darwin's supporters and the authorities of the Geological Society, but this unpleasant subject has been disposed of, once for all, by Huxley. ("Essays upon some Controverted Questions", London, 1892, pages 314-328 and 623-625.) Darwin's final and very characteristic utterance on the coral-reef controversy is found in a letter which he wrote to Professor Alexander Agassiz, May 5th, 1881: less than a year before his death: "If I am wrong, the sooner I am knocked on the head and annihilated so much the better. It still seems to me a marvellous thing that there should not have been much, and long-continued, subsidence in the beds of the great oceans. I wish that some doubly rich millionaire would take it into his head to have borings made in some of the Pacific and Indian atolls, and bring home cores for slicing from a depth of 500 or 600 feet." ("L.L." III. page 184.) Though the "doubly rich millionaire" has not been forthcoming, the energy, in England, of Professor Sollas, and in New South Wales of Professor Anderson Stuart served to set on foot a project, which, aided at first by the British Association for the Advancement of Science, and afterwards taken up jointly by the Royal Society, the New South Wales Government, and the Admiralty, has led to the most definite and conclusive results. The Committee appointed by the Royal Society to carry out the undertaking included representatives of all the views that had been put forward on the subject. The place for the experiment was, with the consent of every member of the Committee, selected by the late Admiral Sir W.J. Wharton--who was not himself an adherent of Darwin's views--and no one has ventured to suggest that his selection, the splendid atoll of Funafuti, was not a most judicious one. By the pluck and perseverance of Professor Sollas in the preliminary expedition, and of Professor T. Edgeworth David and his pupils, in subsequent investigations of the island, the rather difficult piece of work was brought to a highly satisfactory conclusion. The New South Wales Government lent boring apparatus and workmen, and the Admiralty carried the expedition to its destination in a surveying ship which, under Captain (now Admiral) A. Mostyn Field, made the most complete survey of the atoll and its surrounding seas that has ever been undertaken in the case of a coral formation. After some failures and many interruptions, the boring was carried to the depth of 1114 feet, and the cores obtained were sent to England. Here the examination of the materials was fortunately undertaken by a zoologist of the highest repute, Dr G.J. Hinde--who has a wide experience in the study of organisms by sections--and he was aided at all points by specialists in the British Museum of Natural History and by other naturalists. Nor were the chemical and other problems neglected. The verdict arrived at, after this most exhaustive study of a series of cores obtained from depths twice as great as that thought necessary by Darwin, was as follows:--"The whole of the cores are found to be built up of those organisms which are seen forming coral-reefs near the surface of the ocean--many of them evidently in situ; and not the slightest indication could be detected, by chemical or microscopic means, which suggested the proximity of non-calcareous rocks, even in the lowest portions brought up." But this was not all. Professor David succeeded in obtaining the aid of a very skilful engineer from Australia, while the Admiralty allowed Commander F.C.D. Sturdee to take a surveying ship into the lagoon for further investigations. By very ingenious methods, and with great perseverance, two borings were put down in the midst of the lagoon to the depth of nearly 200 feet. The bottom of the lagoon, at the depth of 101 1/2 feet from sea-level, was found to be covered with remains of the calcareous, green sea-weed Halimeda, mingled with many foraminifera; but at a depth of 163 feet from the surface of the lagoon the boring tools encountered great masses of coral, which were proved from the fragments brought up to belong to species that live within AT MOST 120 feet from the surface of the ocean, as admitted by all zoologists. ("The Atoll of Funafuti; Report of the Coral Reef Committee of the Royal Society", London, 1904.) Darwin's theory, as is well known, is based on the fact that the temperature of the ocean at any considerable depth does not permit of the existence and luxuriant growth of the organisms that form the reefs. He himself estimated this limit of depth to be from 120 to 130 feet; Dana, as an extreme, 150 feet; while the recent very prolonged and successful investigations of Professor Alexander Agassiz in the Pacific and Indian Oceans lead him also to assign a limiting depth of 150 feet; the EFFECTIVE, REEF-FORMING CORALS, however, flourishing at a much smaller depth. Mr Stanley Gardiner gives for the most important reef-forming corals depths between 30 and 90 feet, while a few are found as low as 120 feet or even 180 feet. It will thus be seen that the verdict of Funafuti is clearly and unmistakeably in favour of Darwin's theory. It is true that some zoologists find a difficulty in realising a slow sinking of parts of the ocean floor, and have suggested new and alternative explanations: but geologists generally, accepting the proofs of slow upheaval in some areas--as shown by the admirable researches of Alexander Agassiz--consider that it is absolutely necessary to admit that this elevation is balanced by subsidence in other areas. If atolls and barrier-reefs did not exist we should indeed be at a great loss to frame a theory to account for their absence. After finishing his book on Coral-reefs, Darwin made his summer excursion to North Wales, and prepared his important memoir on the glaciers of that district: but by October (1842) we find him fairly settled at work upon the second volume of his "Geology of the 'Beagle'--Geological Observations on the Volcanic Islands, visited during the Voyage of H.M.S. 'Beagle'". The whole of the year 1843 was devoted to this work, but he tells his friend Fox that he could "manage only a couple of hours per day, and that not very regularly." ("L.L." I. page 321.) Darwin's work on the various volcanic islands examined by him had given him the most intense pleasure, but the work of writing the book by the aid of his notes and specimens he found "uphill work," especially as he feared the book would not be read, "even by geologists." (Loc. cit.) As a matter of fact the work is full of the most interesting observations and valuable suggestions, and the three editions (or reprints) which have appeared have proved a most valuable addition to geological literature. It is not necessary to refer to the novel and often very striking discoveries described in this well-known work. The subsidence beneath volcanic vents, the enormous denudation of volcanic cones reducing them to "basal wrecks," the effects of solfatarric action and the formation of various minerals in the cavities of rocks--all of these subjects find admirable illustration from his graphic descriptions. One of the most important discussions in this volume is that dealing with the "lamination" of lavas as especially well seen in the rocks of Ascension. Like Scrope, Darwin recognised the close analogy between the structure of these rocks and those of metamorphic origin--a subject which he followed out in the volume "Geological Observations on South America". Of course in these days, since the application of the microscope to the study of rocks in thin sections, Darwin's nomenclature and descriptions of the petrological characters of the lavas appear to us somewhat crude. But it happened that the "Challenger" visited most of the volcanic islands described by Darwin, and the specimens brought home were examined by the eminent petrologist Professor Renard. Renard was so struck with the work done by Darwin, under disadvantageous conditions, that he undertook a translation of Darwin's work into French, and I cannot better indicate the manner in which the book is regarded by geologists than by quoting a passage from Renard's preface. Referring to his own work in studying the rocks brought home by the "Challenger" (Renard's descriptions of these rocks are contained in the "Challenger Reports". Mr Harker is supplementing these descriptions by a series of petrological memoirs on Darwin's specimens, the first of which appeared in the "Geological Magazine" for March, 1907.), he says: "Je dus, en me livrant a ces recherches, suivre ligne par ligne les divers chapitres des "Observations geologiques" consacrees aux iles de l'Atlantique, oblige que j'etais de comparer d'une maniere suivie les resultats auxquels j'etais conduit avec ceux de Darwin, qui servaient de controle a mes constatations. Je ne tardai pas a eprouver une vive admiration pour ce chercheur qui, sans autre appareil que la loupe, sans autre reaction que quelques essais pyrognostiques, plus rarement quelques mesures au goniometre, parvenait a discerner la nature des agregats mineralogiques les plue complexes et les plus varies. Ce coup d'oeil qui savait embrasser de si vastes horizons, penetre ici profondement tous les details lithologiques. Avec quelle surete et quelle exactitude la structure et la composition des roches ne sont'elles pas determinees, l'origne de ces masses minerales deduite et confirmee par l'etude comparee des manifestations volcaniques d'autres regions; avec quelle science les relations entre les faits qu'il decouvre et ceux signales ailleurs par ses devanciers ne sont'elles pas etablies, et comme voici ebranlees les hypotheses regnantes, admises sans preuves, celles, par exemple, des crateres de soulevement et de la differenciation radicale des phenomenes plutoniques et volcaniques! Ce qui acheve de donner a ce livre un incomparable merite, ce sont les idees nouvelles qui s'y trouvent en germe et jetees la comme au hasard ainsi qu'un superflu d'abondance intellectuelle inepuisable." ("Observations Geologiques sur les Iles Volcaniques... ", Paris, 1902, pages vi., vii.) While engaged in his study of banded lavas, Darwin was struck with the analogy of their structure with that of glacier ice, and a note on the subject, in the form of a letter addressed to Professor J.D. Forbes, was published in the "Proceedings of the Royal Society of Edinburgh". (Vol. II. (1844-5), pages 17, 18.) From April, 1832, to September, 1835, Darwin had been occupied in examining the coast or making inland journeys in the interior of the South American continent. Thus while eighteen months were devoted, at the beginning and end of the voyage to the study of volcanic islands and coral-reefs, no less than three and a half years were given to South American geology. The heavy task of dealing with the notes and specimens accumulated during that long period was left by Darwin to the last. Finishing the "Volcanic Islands" on February 14th, 1844, he, in July of the same year, commenced the preparation of two important works which engaged him till near the end of the year 1846. The first was his "Geological Observations on South America", the second a recast of his "Journal", published under the short title of "A Naturalist's Voyage round the World". The first of these works contains an immense amount of information collected by the author under great difficulties and not unfrequently at considerable risk to life and health. No sooner had Darwin landed in South America than two sets of phenomena powerfully arrested his attention. The first of these was the occurrence of great masses of red mud containing bones and shells, which afforded striking evidence that the whole continent had shared in a series of slow and gradual but often interrupted movements. The second related to the great masses of crystalline rocks which, underlying the muds, cover so great a part of the continent. Darwin, almost as soon as he landed, was struck by the circumstance that the direction, as shown by his compass, of the prominent features of these great crystalline rock-masses--their cleavage, master-joints, foliation and pegmatite veins--was the same as the orientation described by Humboldt (whose works he had so carefully studied) on the west of the same great continent. The first five chapters of the book on South America were devoted to formations of recent date and to the evidence collected on the east and west coasts of the continent in regard to those grand earth-movements, some of which could be shown to have been accompanied by earthquake-shocks. The fossil bones, which had given him the first hint concerning the mutability of species, had by this time been studied and described by comparative anatomists, and Darwin was able to elaborate much more fully the important conclusion that the existing fauna of South America has a close analogy with that of the period immediately preceding our own. The remaining three chapters of the book dealt with the metamorphic and plutonic rocks, and in them Darwin announced his important conclusions concerning the relations of cleavage and foliation, and on the close analogy of the latter structure with the banding found in rock-masses of igneous origin. With respect to the first of these conclusions, he received the powerful support of Daniel Sharpe, who in the years 1852 and 1854 published two papers on the structure of the Scottish Highlands, supplying striking confirmation of the correctness of Darwin's views. Although Darwin's and Sharpe's conclusions were contested by Murchison and other geologists, they are now universally accepted. In his theory concerning the origin of foliation, Darwin had been to some extent anticipated by Scrope, but he supplied many facts and illustrations leading to the gradual acceptance of a doctrine which, when first enunciated, was treated with neglect, if not with contempt. The whole of this volume on South American geology is crowded with the records of patient observations and suggestions of the greatest value; but, as Darwin himself saw, it was a book for the working geologist and "caviare to the general." Its author, indeed, frequently expressed his sense of the "dryness" of the book; he even says "I long hesitated whether I would publish it or not," and he wrote to Leonard Horner "I am astonished that you should have had the courage to go right through my book." ("M.L." II. page 221.) Fortunately the second book, on which Darwin was engaged at this time, was of a very different character. His "Journal", almost as he had written it on board ship, with facts and observations fresh in his mind, had been published in 1839 and attracted much attention. In 1845, he says, "I took much pains in correcting a new edition," and the work which was commenced in April, 1845, was not finished till August of that year. The volume contains a history of the voyage with "a sketch of those observations in Natural History and Geology, which I think will possess some interest for the general reader." It is not necessary to speak of the merits of this scientific classic. It became a great favourite with the general public--having passed through many editions--it was, moreover, translated into a number of different languages. Darwin was much gratified by these evidences of popularity, and naively remarks in his "Autobiography", "The success of this my first literary child tickles my vanity more than that of any of my other books" ("L.L." I. page 80.)--and this was written after the "Origin of Species" had become famous! In Darwin's letters there are many evidences that his labours during these ten years devoted to the working out of the geological results of the voyage often made many demands on his patience and indomitable courage. Most geologists have experience of the contrast between the pleasures felt when wielding the hammer in the field, and the duller labour of plying the pen in the study. But in Darwin's case, innumerable interruptions from sickness and other causes, and the oft-deferred hope of reaching the end of his task were not the only causes operating to make the work irksome. The great project, which was destined to become the crowning achievement of his life, was now gradually assuming more definite shape, and absorbing more of his time and energies. Nevertheless, during all this period, Darwin so far regarded his geological pursuits as his PROPER "work," that attention to other matters was always spoken of by him as "indulging in idleness." If at the end of this period the world had sustained the great misfortune of losing Darwin by death before the age of forty--and several times that event seemed only too probable--he might have been remembered only as a very able geologist of most advanced views, and a traveller who had written a scientific narrative of more than ordinary excellence! The completion of the "Geology of the 'Beagle'" and the preparation of a revised narrative of the voyage mark the termination of that period of fifteen years of Darwin's life during which geological studies were his principal occupation. Henceforth, though his interest in geological questions remained ever keen, biological problems engaged more and more of his attention to the partial exclusion of geology. The eight years from October, 1846, to October, 1854, were mainly devoted to the preparation of his two important monographs on the recent and fossil Cirripedia. Apart from the value of his description of the fossil forms, this work of Darwin's had an important influence on the progress of geological science. Up to that time a practice had prevailed for the student of a particular geological formation to take up the description of the plant and animal remains in it--often without having anything more than a rudimentary knowledge of the living forms corresponding to them. Darwin in his monograph gave a very admirable illustration of the enormous advantage to be gained--alike for biology and geology--by undertaking the study of the living and fossil forms of a natural group of organisms in connection with one another. Of the advantage of these eight years of work to Darwin himself, in preparing for the great task lying before him, Huxley has expressed a very strong opinion indeed. ("L.L." II. pages 247-48.) But during these eight years of "species work," Darwin found opportunities for not a few excursions into the field of geology. He occasionally attended the Geological Society, and, as we have already seen, read several papers there during this period. His friend, Dr Hooker, then acting as botanist to the Geological Survey, was engaged in studying the Carboniferous flora, and many discussions on Palaezoic plants and on the origin of coal took place at this period. On this last subject he felt the deepest interest and told Hooker, "I shall never rest easy in Down churchyard without the problem be solved by some one before I die." ("M.L." I. pages 63, 64.) As at all times, conversations and letters with Lyell on every branch of geological science continued with unabated vigour, and in spite of the absorbing character of the work on the Cirripedes, time was found for all. In 1849 his friend Herschel induced him to supply a chapter of forty pages on Geology to the Admiralty "Manual of Scientific Inquiry" which he was editing. This is Darwin's single contribution to books of an "educational" kind. It is remarkable for its clearness and simplicity and attention to minute details. It may be read by the student of Darwin's life with much interest, for the directions he gives to an explorer are without doubt those which he, as a self-taught geologist, proved to be serviceable during his life on the "Beagle". On the completion of the Cirripede volumes, in 1854, Darwin was able to grapple with the immense pile of MS. notes which he had accumulated on the species question. The first sketch of 35 pages (1842), had been enlarged in 1844 into one of 230 pages ([The first draft of the "Origin" is being prepared for Press by Mr Francis Darwin and will be published by the Cambridge University Press this year (1909). A.C.S.]); but in 1856 was commenced the work (never to be completed) which was designed on a scale three or four times more extensive than that on which the "Origin of Species" was in the end written. In drawing up those two masterly chapters of the "Origin", "On the Imperfection of the Geological Record," and "On the Geological Succession of Organic Beings", Darwin had need of all the experience and knowledge he had been gathering during thirty years, the first half of which had been almost wholly devoted to geological study. The most enlightened geologists of the day found much that was new, and still more that was startling from the manner of its presentation, in these wonderful essays. Of Darwin's own sense of the importance of the geological evidence in any presentation of his theory a striking proof will be found in a passage of the touching letter to his wife, enjoining the publication of his sketch of 1844. "In case of my sudden death," he wrote, "... the editor must be a geologist as well as a naturalist." ("L.L." II. pages 16, 17.) In spite of the numerous and valuable palaeontological discoveries made since the publication of "The Origin of Species", the importance of the first of these two geological chapters is as great as ever. It still remains true that "Those who believe that the geological record is in any degree perfect, will at once reject the theory"--as indeed they must reject any theory of evolution. The striking passage with which Darwin concludes this chapter--in which he compares the record of the rocks to the much mutilated volumes of a human history--remains as apt an illustration as it did when first written. And the second geological chapter, on the Succession of Organic Beings--though it has been strengthened in a thousand ways, by the discoveries concerning the pedigrees of the horse, the elephant and many other aberrant types, though new light has been thrown even on the origin of great groups like the mammals, and the gymnosperms, though not a few fresh links have been discovered in the chains of evidence, concerning the order of appearance of new forms of life--we would not wish to have re-written. Only the same line of argument could be adopted, though with innumerable fresh illustrations. Those who reject the reasonings of this chapter, neither would they be persuaded if a long and complete succession of "ancestral forms" could rise from the dead and pass in procession before them. Among the geological discussions, which so frequently occupied Darwin's attention during the later years of his life, there was one concerning which his attitude seemed somewhat remarkable--I allude to his views on "the permanence of Continents and Ocean-basins." In a letter to Mr Mellard Reade, written at the end of 1880, he wrote: "On the whole, I lean to the side that the continents have since Cambrian times occupied approximately their present positions. But, as I have said, the question seems a difficult one, and the more it is discussed the better." ("M.L." II. page 147.) Since this was written, the important contribution to the subject by the late Dr W.T. Blanford (himself, like Darwin, a naturalist and geologist) has appeared in an address to the Geological Society in 1890; and many discoveries, like that of Dr Woolnough in Fiji, have led to considerable qualifications of the generalisation that all the islands in the great ocean are wholly of volcanic or coral origin. I remember once expressing surprise to Darwin that, after the views which he had originated concerning the existence of areas of elevation and others of subsidence in the Pacific Ocean, and in face of the admitted difficulty of accounting for the distribution of certain terrestrial animals and plants, if the land and sea areas had been permanent in position, he still maintained that theory. Looking at me with a whimsical smile, he said: "I have seen many of my old friends make fools of themselves, by putting forward new theoretical views or revising old ones, AFTER THEY WERE SIXTY YEARS OF AGE; so, long ago, I determined that on reaching that age I would write nothing more of a speculative character." Though Darwin's letters and conversations on geology during these later years were the chief manifestations of the interest he preserved in his "old love," as he continued to call it, yet in the sunset of that active life a gleam of the old enthusiasm for geology broke forth once more. There can be no doubt that Darwin's inability to occupy himself with field-work proved an insuperable difficulty to any attempt on his part to resume active geological research. But, as is shown by the series of charming volumes on plant-life, Darwin had found compensation in making patient and persevering experiment take the place of enterprising and exact observation; and there was one direction in which he could indulge the "old love" by employment of the new faculty. We have seen that the earliest memoir written by Darwin, which was published in full, was a paper "On the Formation of Mould" which was read at the Geological Society on November 1st, 1837, but did not appear in the "Transactions" of the Society till 1840, where it occupied four and a half quarto pages, including some supplementary matter, obtained later, and a woodcut. This little paper was confined to observations made in his uncle's fields in Staffordshire, where burnt clay, cinders, and sand were found to be buried under a layer of black earth, evidently brought from below by earthworms, and to a recital of similar facts from Scotland obtained through the agency of Lyell. The subsequent history of Darwin's work on this question affords a striking example of the tenacity of purpose with which he continued his enquiries on any subject that interested him. In 1842, as soon as he was settled at Down, he began a series of observations on a foot-path and in his fields, that continued with intermissions during his whole life, and he extended his enquiries from time to time to the neighbouring parks of Knole and Holwood. In 1844 we find him making a communication to the "Gardener's Chronicle" on the subject. About 1870, his attention to the question was stimulated by the circumstance that his niece (Miss L. Wedgwood) undertook to collect and weigh the worm-casts thrown up, during a whole year, on measured squares selected for the purpose, at Leith Hill Place. He also obtained information from Professor Ramsay concerning observations made by him on a pavement near his house in 1871. Darwin at this time began to realise the great importance of the action of worms to the archaeologist. At an earlier date he appears to have obtained some information concerning articles found buried on the battle-field of Shrewsbury, and the old Roman town of Uriconium, near his early home; between 1871 and 1878 Mr (afterwards Lord) Farrer carried on a series of investigations at the Roman Villa discovered on his land at Abinger; Darwin's son William examined for his father the evidence at Beaulieu Abbey, Brading, Stonehenge and other localities in the neighbourhood of his home; his sons Francis and Horace were enlisted to make similar enquiries at Chideock and Silchester; while Francis Galton contributed facts noticed in his walks in Hyde Park. By correspondence with Fritz Muller and Dr Ernst, Darwin obtained information concerning the worm-casts found in South America; from Dr Kreft those of Australia; and from Mr Scott and Dr (afterwards Sir George) King, those of India; the last-named correspondent also supplied him with much valuable information obtained in the South of Europe. Help too was obtained from the memoirs on Earthworms published by Perrier in 1874 and van Hensen in 1877, while Professor Ray Lankester supplied important facts with regard to their anatomy. When therefore the series of interesting monographs on plant-life had been completed, Darwin set to work in bringing the information that he had gradually accumulated during forty-four years to bear on the subject of his early paper. He also utilised the skill and ingenuity he had acquired in botanical work to aid in the elucidation of many of the difficulties that presented themselves. I well remember a visit which I paid to Down at this period. At the side of the little study stood flower-pots containing earth with worms, and, without interrupting our conversation, Darwin would from time to time lift the glass plate covering a pot to watch what was going on. Occasionally, with a humorous smile, he would murmur something about a book in another room, and slip away; returning shortly, without the book but with unmistakeable signs of having visited the snuff-jar outside. After working about a year at the worms, he was able at the end of 1881 to publish the charming little book--"The Formation of Vegetable Mould through the Action of Worms, with Observations on their Habits". This was the last of his books, and its reception by reviewers and the public alike afforded the patient old worker no little gratification. Darwin's scientific career, which had begun with geological research, most appropriately ended with a return to it. It has been impossible to sketch the origin and influence of Darwin's geological work without, at almost every step, referring to the part played by Lyell and the "Principles of Geology". Haeckel, in the chapters on Lyell and Darwin in his "History of Creation", and Huxley in his striking essay "On the Reception of the Origin of Species" ("L.L." II. pages 179-204.) have both strongly insisted on the fact that the "Origin" of Darwin was a necessary corollary to the "Principles" of Lyell. It is true that, in an earlier essay, Huxley had spoken of the doctrine of Uniformitarianism as being, in a certain sense, opposed to that of Evolution (Huxley's Address to the Geological Society, 1869. "Collected Essays", Vol. VIII. page 305, London, 1896.); but in his later years he took up a very different and more logical position, and maintained that "Consistent uniformitarianism postulates evolution as much in the organic as in the inorganic world. The origin of a new species by other than ordinary agencies would be a vastly greater 'catastrophe' than any of those which Lyell success fully eliminated from sober geological speculation." ("L.L." II. page 190.) Huxley's admiration for the "Principles of Geology", and his conviction of the greatness of the revolution of thought brought about by Lyell, was almost as marked as in the case of Darwin himself. (See his Essay on "Science and Pseudo Science". "Collected Essays", Vol. V. page 90, London, 1902.) He felt, however, as many others have done, that in one respect the very success of Lyell's masterpiece has been the reason why its originality and influence have not been so fully recognised as they deserved to be. Written as the book was before its author had arrived at the age of thirty, no less than eleven editions of the "Principles" were called for in his lifetime. With the most scrupulous care, Lyell, devoting all his time and energies to the task of collecting and sifting all evidence bearing on the subjects of his work, revised and re-revised it; and as in each edition, eliminations, modifications, corrections, and additions were made, the book, while it increased in value as a storehouse of facts, lost much of its freshness, vigour and charm as a piece of connected reasoning. Darwin undoubtedly realised this when he wrote concerning the "Principles", "the first edition, my old true love, which I never deserted for the later editions." ("M.L." II. page 222.) Huxley once told me that when, in later life, he read the first edition, he was both surprised and delighted, feeling as if it were a new book to him. (I have before me a letter which illustrates this feeling on Huxley's part. He had lamented to me that he did not possess a copy of the first edition of the "Principles", when, shortly afterwards, I picked up a dilapidated copy on a bookstall; this I had bound and sent to my old teacher and colleague. His reply is characteristic: October 8, 1884. My Dear Judd, You could not have made me a more agreeable present than the copy of the first edition of Lyell, which I find on my table. I have never been able to meet with the book, and your copy is, as the old woman said of her Bible, "the best of books in the best of bindings." Ever yours sincerely, T.H. Huxley. (I cannot refrain from relating an incident which very strikingly exemplifies the affection for one another felt by Lyell and Huxley. In his last illness, when confined to his bed, Lyell heard that Huxley was to lecture at the Royal Institution on the "Results of the 'Challenger' expedition": he begged me to attend the lecture and bring him an account of it. Happening to mention this to Huxley, he at once undertook to go to Lyell in my place, and he did so on the morning following his lecture. I shall never forget the look of gratitude on the face of the invalid when he told me, shortly afterwards, how Huxley had sat by his bedside and "repeated the whole lecture to him.") Darwin's generous nature seems often to have made him experience a fear lest he should do less than justice to his "dear old master," and to the influence that the "Principles of Geology" had in moulding his mind. In 1845 he wrote to Lyell, "I have long wished, not so much for your sake, as for my own feelings of honesty, to acknowledge more plainly than by mere reference, how much I geologically owe you. Those authors, however, who like you, educate people's minds as well as teach them special facts, can never, I should think, have full justice done them except by posterity, for the mind thus insensibly improved can hardly perceive its own upward ascent." ("L.L." I. pages 337-8.) In another letter, to Leonard Horner, he says: "I always feel as if my books came half out of Lyell's brain, and that I never acknowledge this sufficiently." ("M.L." II. page 117.) Darwin's own most favourite book, the "Narrative of the Voyage", was dedicated to Lyell in glowing terms; and in the "Origin of Species" he wrote of "Lyell's grand work on the "Principles of Geology", which the future historian will recognise as having produced a revolution in Natural Science." "What glorious good that work has done" he fervently exclaims on another occasion. ("L.L." I. page 342.) To the very end of his life, as all who were in the habit of talking with Darwin can testify, this sense of his indebtedness to Lyell remained with him. In his "Autobiography", written in 1876, the year after Lyell's death, he spoke in the warmest terms of the value to him of the "Principles" while on the voyage and of the aid afforded to him by Lyell on his return to England. ("L.L." I. page 62.) But the year before his own death, Darwin felt constrained to return to the subject and to place on record a final appreciation--one as honourable to the writer as it is to his lost friend: "I saw more of Lyell than of any other man, both before and after my marriage. His mind was characterised, as it appeared to me, by clearness, caution, sound judgment, and a good deal of originality. When I made any remark to him on Geology, he never rested until he saw the whole case clearly, and often made me see it more clearly than I had done before. He would advance all possible objections to my suggestion, and even after these were exhausted would remain long dubious. A second characteristic was his hearty sympathy with the work of other scientific men... His delight in science was ardent, and he felt the keenest interest in the future progress of mankind. He was very kind-hearted... His candour was highly remarkable. He exhibited this by becoming a convert to the Descent theory, though he had gained much fame by opposing Lamarck's views, and this after he had grown old." "THE SCIENCE OF GEOLOGY IS ENORMOUSLY INDEBTED TO LYELL--MORE SO, AS I BELIEVE, THAN TO ANY OTHER MAN WHO EVER LIVED." ("L.L." I. pages 71-2 (the italics are mine.)) Those who knew Lyell intimately will recognise the truth of the portrait drawn by his dearest friend, and I believe that posterity will endorse Darwin's deliberate verdict concerning the value of his labours. It was my own good fortune, to be brought into close contact with these two great men during the later years of their life, and I may perhaps be permitted to put on record the impressions made upon me during friendly intercourse with both. In some respects, there was an extraordinary resemblance in their modes and habits of thought, between Lyell and Darwin; and this likeness was also seen in their modesty, their deference to the opinion of younger men, their enthusiasm for science, their freedom from petty jealousies and their righteous indignation for what was mean and unworthy in others. But yet there was a difference. Both Lyell and Darwin were cautious, but perhaps Lyell carried his caution to the verge of timidity. I think Darwin possessed, and Lyell lacked, what I can only describe by the theological term, "faith--the substance of things hoped for, the evidence of things not seen." Both had been constrained to feel that the immutability of species could not be maintained. Both, too, recognised the fact that it would be useless to proclaim this conviction, unless prepared with a satisfactory alternative to what Huxley called "the Miltonic hypothesis." But Darwin's conviction was so far vital and operative that it sustained him while working unceasingly for twenty-two years in collecting evidence bearing on the question, till at last he was in the position of being able to justify that conviction to others. And yet Lyell's attitude--and that of Hooker, which was very similar--proved of inestimable service to science, as Darwin often acknowledged. One of the greatest merits of the "Origin of Species" is that so many difficulties and objections are anticipated and fairly met; and this was to a great extent the result of the persistent and very candid--if always friendly--criticism of Lyell and Hooker. I think the divergence of mental attitude in Lyell and Darwin must be attributed to a difference in temperament, the evidence of which sometimes appears in a very striking manner in their correspondence. Thus in 1838, while they were in the thick of the fight with the Catastrophists of the Geological Society, Lyell wrote characteristically: "I really find, when bringing up my Preliminary Essays in "Principles" to the science of the present day, so far as I know it, that the great outline, and even most of the details, stand so uninjured, and in many cases they are so much strengthened by new discoveries, especially by yours, that we may begin to hope that the great principles there insisted on will stand the test of new discoveries." (Lyell's "Life, Letters and Journals", Vol. II. page 44.) To which the more youthful and impetuous Darwin replies: "BEGIN TO HOPE: why the POSSIBILITY of a doubt has never crossed my mind for many a day. This may be very unphilosophical, but my geological salvation is staked on it... it makes me quite indignant that you should talk of HOPING." ("L.L." I. page 296.) It was not only Darwin's "geological salvation" that was at stake, when he surrendered himself to his enthusiasm for an idea. To his firm faith in the doctrine of continuity we owe the "Origin of Species"; and while Darwin became the "Paul" of evolution, Lyell long remained the "doubting Thomas." Many must have felt like H.C. Watson when he wrote: "How could Sir C. Lyell... for thirty years read, write, and think, on the subject of species AND THEIR SUCCESSION, and yet constantly look down the wrong road!" ("L.L." II. page 227.) Huxley attributed this hesitation of Lyell to his "profound antipathy" to the doctrine of the "pithecoid origin of man." ("L.L." II. page 193.) Without denying that this had considerable influence (and those who knew Lyell and his great devotion to his wife and her memory, are aware that he and she felt much stronger convictions concerning such subjects as the immortality of the soul than Darwin was able to confess to) yet I think Darwin had divined the real characteristics of his friend's mind, when he wrote: "He would advance all possible objections... AND EVEN AFTER THESE WERE EXHAUSTED, WOULD REMAIN LONG DUBIOUS." Very touching indeed was the friendship maintained to the end between these two leaders of thought--free as their intercourse was from any smallest trace of self-seeking or jealousy. When in 1874 I spent some time with Lyell in his Forfarshire home, a communication from Darwin was always an event which made a "red-letter day," as Lyell used to say; and he gave me many indications in his conversation of how strongly he relied upon the opinion of Darwin--more indeed than on the judgment of any other man--this confidence not being confined to questions of science, but extending to those of morals, politics, and religion. I have heard those who knew Lyell only slightly, speak of his manners as cold and reserved. His complete absorption in his scientific work, coupled with extreme short-sightedness, almost in the end amounting to blindness, may have permitted those having but a casual acquaintance with him to accept such a view. But those privileged to know him intimately recognised the nobleness of his character and can realise the justice and force of Hooker's words when he heard of his death: "My loved, my best friend, for well nigh forty years of my life. The most generous sharer of my own and my family's hopes, joys and sorrows, whose affection for me was truly that of a father and brother combined." But the strongest of all testimonies to the grandeur of Lyell's character is the lifelong devotion to him of such a man as Darwin. Before the two met, we find Darwin constantly writing of facts and observations that he thinks "will interest Mr Lyell"; and when they came together the mutual esteem rapidly ripened into the warmest affection. Both having the advantage of a moderate independence, permitting of an entire devotion of their lives to scientific research, they had much in common, and the elder man--who had already achieved both scientific and literary distinction--was able to give good advice and friendly help to the younger one. The warmth of their friendship comes out very strikingly in their correspondence. When Darwin first conceived the idea of writing a book on the "species question," soon after his return from the voyage, it was "by following the example of Lyell in Geology" that he hoped to succeed ("L.L." I. page 83.); when in 1844, Darwin had finished his first sketch of the work, and, fearing that his life might not be spared to complete his great undertaking, committed the care of it in a touching letter to his wife, it was his friend Lyell whom he named as her adviser and the possible editor of the book ("L.L." II. pages 17-18.); it was Lyell who, in 1856, induced Darwin to lay the foundations of a treatise ("L.L." I. page 84.) for which the author himself selected the "Principles" as his model; and when the dilemma arose from the receipt of Wallace's essay, it was to Lyell jointly with Hooker that Darwin turned, not in vain, for advice and help. During the later years of his life, I never heard Darwin allude to his lost friend--and he did so very often--without coupling his name with some term of affection. For a brief period, it is true, Lyell's excessive caution when the "Origin" was published, seemed to try even the patience of Darwin; but when "the master" was at last able to declare himself fully convinced, he was the occasion of more rejoicing on the part of Darwin, than any other convert to his views. The latter was never tired of talking of Lyell's "magnanimity" and asserted that, "To have maintained in the position of a master, one side of a question for thirty years, and then deliberately give it up, is a fact to which I much doubt whether the records of science offer a parallel." ("L.L." II. pages 229-30.) Of Darwin himself, I can safely affirm that I never knew anyone who had met him, even for the briefest period, who was not charmed by his personality. Who could forget the hearty hand-grip at meeting, the gentle and lingering pressure of the palm at parting, and above all that winning smile which transformed his countenance--so as to make portraits, and even photographs, seem ever afterwards unsatisfying! Looking back, one is indeed tempted to forget the profoundness of the philosopher, in recollection of the loveableness of the man. XIX. DARWIN'S WORK ON THE MOVEMENTS OF PLANTS. By Francis Darwin, Honorary Fellow of Christ's College, Cambridge. My father's interest in plants was of two kinds, which may be roughly distinguished as EVOLUTIONARY and PHYSIOLOGICAL. Thus in his purely evolutionary work, for instance in "The Origin of Species" and in his book on "Variation under Domestication", plants as well as animals served as material for his generalisations. He was largely dependent on the work of others for the facts used in the evolutionary work, and despised himself for belonging to the "blessed gang" of compilers. And he correspondingly rejoiced in the employment of his wonderful power of observation in the physiological problems which occupied so much of his later life. But inasmuch as he felt evolution to be his life's work, he regarded himself as something of an idler in observing climbing plants, insectivorous plants, orchids, etc. In this physiological work he was to a large extent urged on by his passionate desire to understand the machinery of all living things. But though it is true that he worked at physiological problems in the naturalist's spirit of curiosity, yet there was always present to him the bearing of his facts on the problem of evolution. His interests, physiological and evolutionary, were indeed so interwoven that they cannot be sharply separated. Thus his original interest in the fertilisation of flowers was evolutionary. "I was led" ("Life and Letters", I. page 90.), he says, "to attend to the cross-fertilisation of flowers by the aid of insects, from having come to the conclusion in my speculations on the origin of species, that crossing played an important part in keeping specific forms constant." In the same way the value of his experimental work on heterostyled plants crystalised out in his mind into the conclusion that the product of illegitimate unions are equivalent to hybrids--a conclusion of the greatest interest from an evolutionary point of view. And again his work "Cross and Self Fertilisation" may be condensed to a point of view of great importance in reference to the meaning and origin of sexual reproduction. (See Professor Goebel's article in the present volume.) The whole of his physiological work may be looked at as an illustration of the potency of his theory as an "instrument for the extension of the realm of natural knowledge." (Huxley in Darwin's "Life and Letters." II. page 204.) His doctrine of natural selection gave, as is well known, an impulse to the investigation of the use of organs--and thus created the great school of what is known in Germany as Biology--a department of science for which no English word exists except the rather vague term Natural History. This was especially the case in floral biology, and it is interesting to see with what hesitation he at first expressed the value of his book on Orchids ("Life and Letters", III. page 254.), "It will perhaps serve to illustrate how Natural History may be worked under the belief of the modification of species" (1861). And in 1862 he speaks (Loc. cit.) more definitely of the relation of his work to natural selection: "I can show the meaning of some of the apparently meaningless ridges (and) horns; who will now venture to say that this or that structure is useless?" It is the fashion now to minimise the value of this class of work, and we even find it said by a modern writer that to inquire into the ends subserved by organs is not a scientific problem. Those who take this view surely forget that the structure of all living things is, as a whole, adaptive, and that a knowledge of how the present forms come to be what they are includes a knowledge of why they survived. They forget that the SUMMATION of variations on which divergence depends is under the rule of the environment considered as a selective force. They forget that the scientific study of the interdependence of organisms is only possible through a knowledge of the machinery of the units. And that, therefore, the investigation of such widely interesting subjects as extinction and distribution must include a knowledge of function. It is only those who follow this line of work who get to see the importance of minute points of structure and understand as my father did even in 1842, as shown in his sketch of the "Origin" (Now being prepared for publication.), that every grain of sand counts for something in the balance. Much that is confidently stated about the uselessness of different organs would never have been written if the naturalist spirit were commoner nowadays. This spirit is strikingly shown in my father's work on the movements of plants. The circumstance that botanists had not, as a class, realised the interest of the subject accounts for the fact that he was able to gather such a rich harvest of results from such a familiar object as a twining plant. The subject had been investigated by H. von Mohl, Palm, and Dutrochet, but they failed not only to master the problem but (which here concerns us) to give the absorbing interest of Darwin's book to what they discovered. His work on climbing plants was his first sustained piece of work on the physiology of movement, and he remarks in 1864: "This has been new sort of work for me." ("Life and Letters", III. page 315. He had, however, made a beginning on the movements of Drosera.) He goes on to remark with something of surprise, "I have been pleased to find what a capital guide for observations a full conviction of the change of species is." It was this point of view that enabled him to develop a broad conception of the power of climbing as an adaptation by means of which plants are enabled to reach the light. Instead of being compelled to construct a stem of sufficient strength to stand alone, they succeed in the struggle by making use of other plants as supports. He showed that the great class of tendril- and root-climbers which do not depend on twining round a pole, like a scarlet-runner, but on attaching themselves as they grow upwards, effect an economy. Thus a Phaseolus has to manufacture a stem three feet in length to reach a height of two feet above the ground, whereas a pea "which had ascended to the same height by the aid of its tendrils, was but little longer than the height reached." ("Climbing Plants" (2nd edition 1875), page 193.) Thus he was led on to the belief that TWINING is the more ancient form of climbing, and that tendril-climbers have been developed from twiners. In accordance with this view we find LEAF-CLIMBERS, which may be looked on as incipient tendril-bearers, occurring in the same genera with simple twiners. (Loc. cit. page 195.) He called attention to the case of Maurandia semperflorens in which the young flower-stalks revolve spontaneously and are sensitive to a touch, but neither of these qualities is of any perceptible value to the species. This forced him to believe that in other young plants the rudiments of the faculty needed for twining would be found--a prophecy which he made good in his "Power of Movement" many years later. In "Climbing Plants" he did little more than point out the remarkable fact that the habit of climbing is widely scattered through the vegetable kingdom. Thus climbers are to be found in 35 out of the 59 Phanerogamic Alliances of Lindley, so that "the conclusion is forced on our minds that the capacity of revolving (If a twining plant, e.g. a hop, is observed before it has begun to ascend a pole, it will be noticed that, owing to the curvature of the stem, the tip is not vertical but hangs over in a roughly horizontal position. If such a shoot is watched it will be found that if, for instance, it points to the north at a given hour, it will be found after a short interval pointing north-east, then east, and after about two hours it will once more be looking northward. The curvature of the stem depends on one side growing quicker than the opposite side, and the revolving movement, i.e. circumnutation, depends on the region of quickest growth creeping gradually round the stem from south through west to south again. Other plants, e.g. Phaseolus, revolve in the opposite direction.), on which most climbers depend, is inherent, though undeveloped, in almost every plant in the vegetable kingdom." ("Climbing Plants", page 205.) In the "Origin" (Edition I. page 427, Edition VI. page 374.) Darwin speaks of the "apparent paradox, that the very same characters are analogical when one class or order is compared with another, but give true affinities when the members of the same class or order are compared one with another." In this way we might perhaps say that the climbing of an ivy and a hop are analogical; the resemblance depending on the adaptive result rather than on community of blood; whereas the relation between a leaf-climber and a true tendril-bearer reveals descent. This particular resemblance was one in which my father took especial delight. He has described an interesting case occurring in the Fumariaceae. ("Climbing Plants", page 195.) "The terminal leaflets of the leaf-climbing Fumaria officinalis are not smaller than the other leaflets; those of the leaf-climbing Adlumia cirrhosa are greatly reduced; those of Corydalis claviculata (a plant which may be indifferently called a leaf-climber or a tendril-bearer) are either reduced to microscopical dimensions or have their blades wholly aborted, so that this plant is actually in a state of transition; and finally in the Dicentra the tendrils are perfectly characterized." It is a remarkable fact that the quality which, broadly speaking, forms the basis of the climbing habit (namely revolving nutation, otherwise known as circumnutation) subserves two distinct ends. One of these is the finding of a support, and this is common to twiners and tendrils. Here the value ends as far as tendril-climbers are concerned, but in twiners Darwin believed that the act of climbing round a support is a continuation of the revolving movement (circumnutation). If we imagine a man swinging a rope round his head and if we suppose the rope to strike a vertical post, the free end will twine round it. This may serve as a rough model of twining as explained in the "Movements and Habits of Climbing Plants". It is on these points--the nature of revolving nutation and the mechanism of twining--that modern physiologists differ from Darwin. (See the discussion in Pfeffer's "The Physiology of Plants" Eng. Tr. (Oxford, 1906), III. page 34, where the literature is given. Also Jost, "Vorlesungen uber Pflanzenphysiologie", page 562, Jena, 1904.) Their criticism originated in observations made on a revolving shoot which is removed from the action of gravity by keeping the plant slowly rotating about a horizontal axis by means of the instrument known as a klinostat. Under these conditions circumnutation becomes irregular or ceases altogether. When the same experiment is made with a plant which has twined spirally up a stick, the process of climbing is checked and the last few turns become loosened or actually untwisted. From this it has been argued that Darwin was wrong in his description of circumnutation as an automatic change in the region of quickest growth. When the free end of a revolving shoot points towards the north there is no doubt that the south side has been elongating more than the north; after a time it is plain from the shoot hanging over to the east that the west side of the plant has grown most, and so on. This rhythmic change of the position of the region of greatest growth Darwin ascribes to an unknown internal regulating power. Some modern physiologists, however, attempt to explain the revolving movement as due to a particular form of sensitiveness to gravitation which it is not necessary to discuss in detail in this place. It is sufficient for my purpose to point out that Darwin's explanation of circumnutation is not universally accepted. Personally I believe that circumnutation is automatic--is primarily due to internal stimuli. It is however in some way connected with gravitational sensitiveness, since the movement normally occurs round a vertical line. It is not unnatural that, when the plant has no external stimulus by which the vertical can be recognised, the revolving movement should be upset. Very much the same may be said of the act of twining, namely that most physiologists refuse to accept Darwin's view (above referred to) that twining is the direct result of circumnutation. Everyone must allow that the two phenomena are in some way connected, since a plant which circumnutates clockwise, i.e. with the sun, twines in the same direction, and vice versa. It must also be granted that geotropism has a bearing on the problem, since all plants twine upwards, and cannot twine along a horizontal support. But how these two factors are combined, and whether any (and if so what) other factors contribute, we cannot say. If we give up Darwin's explanation, we must at the same time say with Pfeffer that "the causes of twining are... unknown." ("The Physiology of Plants", Eng. Tr. (Oxford, 1906), III. page 37.) Let us leave this difficult question and consider some other points made out in the progress of the work on climbing plants. One result of what he called his "niggling" ("Life and Letters", III. page 312.) work on tendrils was the discovery of the delicacy of their sense of touch, and the rapidity of their movement. Thus in a passion-flower tendril, a bit of platinum wire weighing 1.2 mg. produced curvature ("Climbing Plants", page 171.), as did a loop of cotton weighing 2 mg. Pfeffer ("Untersuchungen a.d. Bot. Inst. z. Tubingen", Bd. I. 1881-85, page 506.), however, subsequently found much greater sensitiveness: thus the tendril of Sicyos angulatus reacted to 0.00025 mg., but this only occurred when the delicate rider of cottonwool fibre was disturbed by the wind. The same author expanded and explained in a most interesting way the meaning of Darwin's observation that tendrils are not stimulated to movement by drops of water resting on them. Pfeffer showed that DIRTY water containing minute particles of clay in suspension acts as a stimulus. He also showed that gelatine acts like pure water; if a smooth glass rod is coated with a 10 per cent solution of gelatine and is then applied to a tendril, no movement occurs in spite of the fact that the gelatine is solid when cold. Pfeffer ("Physiology", Eng. Tr. III. page 52. Pfeffer has pointed out the resemblance between the contact irritability of plants and the human sense of touch. Our skin is not sensitive to uniform pressure such as is produced when the finger is dipped into mercury (Tubingen "Untersuchungen", I. page 504.) generalises the result in the statement that the tendril has a special form of irritability and only reacts to "differences of pressure or variations of pressure in contiguous... regions." Darwin was especially interested in such cases of specialised irritability. For instance in May, 1864, he wrote to Asa Gray ("Life and Letters", III. page 314.) describing the tendrils of Bignonia capreolata, which "abhor a simple stick, do not much relish rough bark, but delight in wool or moss." He received, from Gray, information as to the natural habitat of the species, and finally concluded that the tendrils "are specially adapted to climb trees clothed with lichens, mosses, or other such productions." ("Climbing Plants", page 102.) Tendrils were not the only instance discovered by Darwin of delicacy of touch in plants. In 1860 he had already begun to observe Sundew (Drosera), and was full of astonishment at its behaviour. He wrote to Sir Joseph Hooker ("Life and Letters", III. page 319.): "I have been working like a madman at Drosera. Here is a fact for you which is certain as you stand where you are, though you won't believe it, that a bit of hair 1/78000 of one grain in weight placed on gland, will cause ONE of the gland-bearing hairs of Drosera to curve inwards." Here again Pfeffer (Pfeffer in "Untersuchungen a. d. Bot. Inst. z. Tubingen", I. page 491.) has, as in so many cases, added important facts to my father's observations. He showed that if the leaf of Drosera is entirely freed from such vibrations as would reach it if observed on an ordinary table, it does not react to small weights, so that in fact it was the vibration of the minute fragment of hair on the gland that produced movement. We may fancifully see an adaptation to the capture of insects--to the dancing of a gnat's foot on the sensitive surface. Darwin was fond of telling how when he demonstrated the sensitiveness of Drosera to Mr Huxley and (I think) to Sir John Burdon Sanderson, he could perceive (in spite of their courtesy) that they thought the whole thing a delusion. And the story ended with his triumph when Mr Huxley cried out, "It IS moving." Darwin's work on tendrils has led to some interesting investigations on the mechanisms by which plants perceive stimuli. Thus Pfeffer (Tubingen "Untersuchungen" I. page 524.) showed that certain epidermic cells occurring in tendrils are probably organs of touch. In these cells the protoplasm burrows as it were into cavities in the thickness of the external cell-walls and thus comes close to the surface, being separated from an object touching the tendril merely by a very thin layer of cell-wall substance. Haberlandt ("Physiologische Pflanzenanatomie", Edition III. Leipzig, 1904. "Sinnesorgane im Pflanzenreich", Leipzig, 1901, and other publications.) has greatly extended our knowledge of vegetable structure in relation to mechanical stimulation. He defines a sense-organ as a contrivance by which the DEFORMATION or forcible change of form in the protoplasm--on which mechanical stimulation depends--is rendered rapid and considerable in amplitude ("Sinnesorgane", page 10). He has shown that in certain papillose and bristle-like contrivances, plants possess such sense-organs; and moreover that these contrivances show a remarkable similarity to corresponding sense-organs in animals. Haberlandt and Nemec ("Ber. d. Deutschen bot. Gesellschaft", XVIII. 1900. See F. Darwin, Presidential Address to Section K, British Association, 1904.) published independently and simultaneously a theory of the mechanism by which plants are orientated in relation to gravitation. And here again we find an arrangement identical in principle with that by which certain animals recognise the vertical, namely the pressure of free particles on the irritable wall of a cavity. In the higher plants, Nemec and Haberlandt believe that special loose and freely movable starch-grains play the part of the otoliths or statoliths of the crustacea, while the protoplasm lining the cells in which they are contained corresponds to the sensitive membrane lining the otocyst of the animal. What is of special interest in our present connection is that according to this ingenious theory (The original conception was due to Noll ("Heterogene Induction", Leipzig, 1892), but his view differed in essential points from those here given.) the sense of verticality in a plant is a form of contact-irritability. The vertical position is distinguished from the horizontal by the fact that, in the latter case, the loose starch-grains rest on the lateral walls of the cells instead of on the terminal walls as occurs in the normal upright position. It should be added that the statolith theory is still sub judice; personally I cannot doubt that it is in the main a satisfactory explanation of the facts. With regard to the RAPIDITY of the reaction of tendrils, Darwin records ("Climbing Plants", page 155. Others have observed movement after about 6".) that a Passion-Flower tendril moved distinctly within 25 seconds of stimulation. It was this fact, more than any other, that made him doubt the current explanation, viz. that the movement is due to unequal growth on the two sides of the tendril. The interesting work of Fitting (Pringsheim's "Jahrb." XXXVIII. 1903, page 545.) has shown, however, that the primary cause is not (as Darwin supposed) contraction on the concave, but an astonishingly rapid increase in growth-rate on the convex side. On the last page of "Climbing Plants" Darwin wrote: "It has often been vaguely asserted that plants are distinguished from animals by not having the power of movement. It should rather be said that plants acquire and display this power only when it is of some advantage to them." He gradually came to realise the vividness and variety of vegetable life, and that a plant like an animal has capacities of behaving in different ways under different circumstances, in a manner that may be compared to the instinctive movements of animals. This point of view is expressed in well-known passages in the "Power of Movement". ("The Power of Movement in Plants", 1880, pages 571-3.) "It is impossible not to be struck with the resemblance between the... movements of plants and many of the actions performed unconsciously by the lower animals." And again, "It is hardly an exaggeration to say that the tip of the radicle... having the power of directing the movements of the adjoining parts, acts like the brain of one of the lower animals; the brain being seated within the anterior end of the body, receiving impressions from the sense-organs, and directing the several movements." The conception of a region of perception distinct from a region of movement is perhaps the most fruitful outcome of his work on the movements of plants. But many years before its publication, viz. in 1861, he had made out the wonderful fact that in the Orchid Catasetum ("Life and Letters", III. page 268.) the projecting organs or antennae are sensitive to a touch, and transmit an influence "for more than one inch INSTANTANEOUSLY," which leads to the explosion or violent ejection of the pollinia. And as we have already seen a similar transmission of a stimulus was discovered by him in Sundew in 1860, so that in 1862 he could write to Hooker ("Life and Letters", III. page 321.): "I cannot avoid the conclusion, that Drosera possesses matter at least in some degree analogous in constitution and function to nervous matter." I propose in what follows to give some account of the observations on the transmission of stimuli given in the "Power of Movement". It is impossible within the space at my command to give anything like a complete account of the matter, and I must necessarily omit all mention of much interesting work. One well-known experiment consisted in putting opaque caps on the tips of seedling grasses (e.g. oat and canary-grass) and then exposing them to light from one side. The difference, in the amount of curvature towards the light, between the blinded and unblinded specimens, was so great that it was concluded that the light-sensitiveness resided exclusively in the tip. The experiment undoubtedly proves that the sensitiveness is much greater in the tip than elsewhere, and that there is a transmission of stimulus from the tip to the region of curvature. But Rothert (Rothert, Cohn's "Beitrage", VII. 1894.) has conclusively proved that the basal part where the curvature occurs is also DIRECTLY sensitive to light. He has shown, however, that in other grasses (Setaria, Panicum) the cotyledon is the only part which is sensitive, while the hypocotyl, where the movement occurs, is not directly sensitive. It was however the question of the localisation of the gravitational sense in the tip of the seedling root or radicle that aroused most attention, and it was on this question that a controversy arose which has continued to the present day. The experiment on which Darwin's conclusion was based consisted simply in cutting off the tip, and then comparing the behaviour of roots so treated with that of normal specimens. An uninjured root when placed horizontally regains the vertical by means of a sharp downward curve; not so a decapitated root which continues to grow more or less horizontally. It was argued that this depends on the loss of an organ specialised for the perception of gravity, and residing in the tip of the root; and the experiment (together with certain important variants) was claimed as evidence of the existence of such an organ. It was at once objected that the amputation of the tip might check curvature by interfering with longitudinal growth, on the distribution of which curvature depends. This objection was met by showing that an injury, e.g. splitting the root longitudinally (See F. Darwin, "Linnean Soc. Journal (Bot)." XIX. 1882, page 218.), which does not remove the tip, but seriously checks growth, does not prevent geotropism. This was of some interest in another and more general way, in showing that curvature and longitudinal growth must be placed in different categories as regards the conditions on which they depend. Another objection of a much more serious kind was that the amputation of the tip acts as a shock. It was shown by Rothert (See his excellent summary of the subject in "Flora" 1894 (Erganzungsband), page 199.) that the removal of a small part of the cotyledon of Setaria prevents the plant curving towards the light, and here there is no question of removing the sense-organ since the greater part of the sensitive cotyledon is intact. In view of this result it was impossible to rely on the amputations performed on roots as above described. At this juncture a new and brilliant method originated in Pfeffer's laboratory. (See Pfeffer, "Annals of Botany", VIII. 1894, page 317, and Czapek, Pringsheim's "Jahrb." XXVII. 1895, page 243.) Pfeffer and Czapek showed that it is possible to bend the root of a lupine so that, for instance, the supposed sense-organ at the tip is vertical while the motile region is horizontal. If the motile region is directly sensitive to gravity the root ought to curve downwards, but this did not occur: on the contrary it continued to grow horizontally. This is precisely what should happen if Darwin's theory is the right one: for if the tip is kept vertical, the sense-organ is in its normal position and receives no stimulus from gravitation, and therefore can obviously transmit none to the region of curvature. Unfortunately this method did not convince the botanical world because some of those who repeated Czapek's experiment failed to get his results. Czapek ("Berichte d. Deutsch. bot. Ges." XV. 1897, page 516, and numerous subsequent papers. English readers should consult Czapek in the "Annals of Botany", XIX. 1905, page 75.) has devised another interesting method which throws light on the problem. He shows that roots, which have been placed in a horizontal position and have therefore been geotropically stimulated, can be distinguished by a chemical test from vertical, i.e. unstimulated roots. The chemical change in the root can be detected before any curvature has occurred and must therefore be a symptom of stimulation, not of movement. It is particularly interesting to find that the change in the root, on which Czapek's test depends, takes place in the tip, i.e. in the region which Darwin held to be the centre for gravitational sensitiveness. In 1899 I devised a method (F. Darwin, "Annals of Botany", XIII. 1899, page 567.) by which I sought to prove that the cotyledon of Setaria is not only the organ for light-perception, but also for gravitation. If a seedling is supported horizontally by pushing the apical part (cotyledon) into a horizontal tube, the cotyledon will, according to my supposition, be stimulated gravitationally and a stimulus will be transmitted to the basal part of the stem (hypocotyl) causing it to bend. But this curvature merely raises the basal end of the seedling, the sensitive cotyledon remains horizontal, imprisoned in its tube; it will therefore be continually stimulated and will continue to transmit influences to the bending region, which should therefore curl up into a helix or corkscrew-like form,--and this is precisely what occurred. I have referred to this work principally because the same method was applied to roots by Massart (Massart, "Mem. Couronnes Acad. R. Belg." LXII. 1902.) and myself (F. Darwin, "Linnean Soc. Journ." XXXV. 1902, page 266.) with a similar though less striking result. Although these researches confirmed Darwin's work on roots, much stress cannot be laid on them as there are several objections to them, and they are not easily repeated. The method which--as far as we can judge at present--seems likely to solve the problem of the root-tip is most ingenious and is due to Piccard. (Pringsheim's "Jahrb." XL. 1904, page 94.) Andrew Knight's celebrated experiment showed that roots react to centrifugal force precisely as they do to gravity. So that if a bean root is fixed to a wheel revolving rapidly on a horizontal axis, it tends to curve away from the centre in the line of a radius of the wheel. In ordinary demonstrations of Knight's experiment the seed is generally fixed so that the root is at right angles to a radius, and as far as convenient from the centre of rotation. Piccard's experiment is arranged differently. (A seed is depicted below a horizontal dotted line AA, projecting a root upwards.) The root is oblique to the axis of rotation, and the extreme tip projects beyond that axis. Line AA represents the axis of rotation, T is the tip of the root just above the line AA, and B is the region just below line AA in which curvature takes place. If the motile region B is directly sensitive to gravitation (and is the only part which is sensitive) the root will curve (down and away from the vertical) away from the axis of rotation, just as in Knight's experiment. But if the tip T is alone sensitive to gravitation the result will be exactly reversed, the stimulus originating in T and conveyed to B will produce curvature (up towards the vertical). We may think of the line AA as a plane dividing two worlds. In the lower one gravity is of the earthly type and is shown by bodies falling and roots curving downwards: in the upper world bodies fall upwards and roots curve in the same direction. The seedling is in the lower world, but its tip containing the supposed sense-organ is in the strange world where roots curve upwards. By observing whether the root bends up or down we can decide whether the impulse to bend originates in the tip or in the motile region. Piccard's results showed that both curvatures occurred and he concluded that the sensitive region is not confined to the tip. (Czapek (Pringsheim's "Jahrb." XXXV. 1900, page 362) had previously given reasons for believing that, in the root, there is no sharp line of separation between the regions of perception and movement.) Haberlandt (Pringsheim's "Jahrb." XLV. 1908, page 575.) has recently repeated the experiment with the advantage of better apparatus and more experience in dealing with plants, and has found as Piccard did that both the tip and the curving region are sensitive to gravity, but with the important addition that the sensitiveness of the tip is much greater than that of the motile region. The case is in fact similar to that of the oat and canary-grass. In both instances my father and I were wrong in assuming that the sensitiveness is confined to the tip, yet there is a concentration of irritability in that region and transmission of stimulus is as true for geotropism as it is for heliotropism. Thus after nearly thirty years the controversy of the root-tip has apparently ended somewhat after the fashion of the quarrels at the "Rainbow" in "Silas Marner"--"you're both right and you're both wrong." But the "brain-function" of the root-tip at which eminent people laughed in early days turns out to be an important part of the truth. (By using Piccard's method I have succeeded in showing that the gravitational sensitiveness of the cotyledon of Sorghum is certainly much greater than the sensitiveness of the hypocotyl--if indeed any such sensitiveness exists. See Wiesner's "Festschrift", Vienna, 1908.) Another observation of Darwin's has given rise to much controversy. ("Power of Movement", page 133.) If a minute piece of card is fixed obliquely to the tip of a root some influence is transmitted to the region of curvature and the root bends away from the side to which the card was attached. It was thought at the time that this proved the root-tip to be sensitive to contact, but this is not necessarily the case. It seems possible that the curvature is a reaction to the injury caused by the alcoholic solution of shellac with which the cards were cemented to the tip. This agrees with the fact given in the "Power of Movement" that injuring the root-tip on one side, by cutting or burning it, induced a similar curvature. On the other hand it was shown that curvature could be produced in roots by cementing cards, not to the naked surface of the root-tip, but to pieces of gold-beaters skin applied to the root; gold-beaters skin being by itself almost without effect. But it must be allowed that, as regards touch, it is not clear how the addition of shellac and card can increase the degree of contact. There is however some evidence that very close contact from a solid body, such as a curved fragment of glass, produces curvature: and this may conceivably be the explanation of the effect of gold-beaters skin covered with shellac. But on the whole it is perhaps safer to classify the shellac experiments with the results of undoubted injury rather than with those of contact. Another subject on which a good deal of labour was expended is the sleep of leaves, or as Darwin called it their NYCTITROPIC movement. He showed for the first time how widely spread this phenomenon is, and attempted to give an explanation of the use to the plant of the power of sleeping. His theory was that by becoming more or less vertical at night the leaves escape the chilling effect of radiation. Our method of testing this view was to fix some of the leaves of a sleeping plant so that they remained horizontal at night and therefore fully exposed to radiation, while their fellows were partly protected by assuming the nocturnal position. The experiments showed clearly that the horizontal leaves were more injured than the sleeping, i.e. more or less vertical, ones. It may be objected that the danger from cold is very slight in warm countries where sleeping plants abound. But it is quite possible that a lowering of the temperature which produces no visible injury may nevertheless be hurtful by checking the nutritive processes (e.g. translocation of carbohydrates), which go on at night. Stahl ("Bot. Zeitung", 1897, page 81.) however has ingeniously suggested that the exposure of the leaves to radiation is not DIRECTLY hurtful because it lowers the temperature of the leaf, but INDIRECTLY because it leads to the deposition of dew on the leaf-surface. He gives reasons for believing that dew-covered leaves are unable to transpire efficiently, and that the absorption of mineral food-material is correspondingly checked. Stahl's theory is in no way destructive of Darwin's, and it is possible that nyctitropic leaves are adapted to avoid the indirect as well as the direct results of cooling by radiation. In what has been said I have attempted to give an idea of some of the discoveries brought before the world in the "Power of Movement" (In 1881 Professor Wiesner published his "Das Bewegungsvermogen der Pflanzen", a book devoted to the criticism of "The Power of Movement in Plants". A letter to Wiesner, published in "Life and Letters", III. page 336, shows Darwin's warm appreciation of his critic's work, and of the spirit in which it is written.) and of the subsequent history of the problems. We must now pass on to a consideration of the central thesis of the book,--the relation of circumnutation to the adaptive curvatures of plants. Darwin's view is plainly stated on pages 3-4 of the "Power of Movement". Speaking of circumnutation he says, "In this universally present movement we have the basis or groundwork for the acquirement, according to the requirements of the plant, of the most diversified movements." He then points out that curvatures such as those towards the light or towards the centre of the earth can be shown to be exaggerations of circumnutation in the given directions. He finally points out that the difficulty of conceiving how the capacities of bending in definite directions were acquired is diminished by his conception. "We know that there is always movement in progress, and its amplitude, or direction, or both, have only to be modified for the good of the plant in relation with internal or external stimuli." It may at once be allowed that the view here given has not been accepted by physiologists. The bare fact that circumnutation is a general property of plants (other than climbing species) is not generally rejected. But the botanical world is no nearer to believing in the theory of reaction built on it. If we compare the movements of plants with those of the lower animals we find a certain resemblance between the two. According to Jennings (H.S. Jennings, "The Behavior of the Lower Animals". Columbia U. Press, N.Y. 1906.) a Paramoecium constantly tends to swerve towards the aboral side of its body owing to certain peculiarities in the set and power of its cilia. But the tendency to swim in a circle, thus produced, is neutralised by the rotation of the creature about its longitudinal axis. Thus the direction of the swerves IN RELATION TO THE PATH of the organism is always changing, with the result that the creature moves in what approximates to a straight line, being however actually a spiral about the general line of progress. This method of motion is strikingly like the circumnutation of a plant, the apex of which also describes a spiral about the general line of growth. A rooted plant obviously cannot rotate on its axis, but the regular series of curvatures of which its growth consists correspond to the aberrations of Paramoecium distributed regularly about its course by means of rotation. (In my address to the Biological Section of the British Association at Cardiff (1891) I have attempted to show the connection between circumnutation and RECTIPETALITY, i.e. the innate capacity of growing in a straight line.) Just as a plant changes its direction of growth by an exaggeration of one of the curvature-elements of which circumnutation consists, so does a Paramoecium change its course by the accentuation of one of the deviations of which its path is built. Jennings has shown that the infusoria, etc., react to stimuli by what is known as the "method of trial." If an organism swims into a region where the temperature is too high or where an injurious substance is present, it changes its course. It then moves forward again, and if it is fortunate enough to escape the influence, it continues to swim in the given direction. If however its change of direction leads it further into the heated or poisonous region it repeats the movement until it emerges from its difficulties. Jennings finds in the movements of the lower organisms an analogue with what is known as pain in conscious organisms. There is certainly this much resemblance that a number of quite different sub-injurious agencies produce in the lower organisms a form of reaction by the help of which they, in a partly fortuitous way, escape from the threatening element in their environment. The higher animals are stimulated in a parallel manner to vague and originally purposeless movements, one of which removes the discomfort under which they suffer, and the organism finally learns to perform the appropriate movement without going through the tentative series of actions. I am tempted to recognise in circumnutation a similar groundwork of tentative movements out of which the adaptive ones were originally selected by a process rudely representative of learning by experience. It is, however, simpler to confine ourselves to the assumption that those plants have survived which have acquired through unknown causes the power of reacting in appropriate ways to the external stimuli of light, gravity, etc. It is quite possible to conceive this occurring in plants which have no power of circumnutating--and, as already pointed out, physiologists do as a fact neglect circumnutation as a factor in the evolution of movements. Whatever may be the fate of Darwin's theory of circumnutation there is no doubt that the research he carried out in support of, and by the light of, this hypothesis has had a powerful influence in guiding the modern theories of the behaviour of plants. Pfeffer ("The Physiology of Plants", Eng. Tr. III. page 11.), who more than any one man has impressed on the world a rational view of the reactions of plants, has acknowledged in generous words the great value of Darwin's work in the same direction. The older view was that, for instance, curvature towards the light is the direct mechanical result of the difference of illumination on the lighted and shaded surfaces of the plant. This has been proved to be an incorrect explanation of the fact, and Darwin by his work on the transmission of stimuli has greatly contributed to the current belief that stimuli act indirectly. Thus we now believe that in a root and a stem the mechanism for the perception of gravitation is identical, but the resulting movements are different because the motor-irritabilities are dissimilar in the two cases. We must come back, in fact, to Darwin's comparison of plants to animals. In both there is perceptive machinery by which they are made delicately alive to their environment, in both the existing survivors are those whose internal constitution has enabled them to respond in a beneficial way to the disturbance originating in their sense-organs. XX. THE BIOLOGY OF FLOWERS. By K. Goebel, Ph.D. Professor of Botany in the University of Munich. There is scarcely any subject to which Darwin devoted so much time and work as to his researches into the biology of flowers, or, in other words, to the consideration of the question to what extent the structural and physiological characters of flowers are correlated with their function of producing fruits and seeds. We know from his own words what fascination these studies possessed for him. We repeatedly find, for example, in his letters expressions such as this:--"Nothing in my life has ever interested me more than the fertilisation of such plants as Primula and Lythrum, or again Anacamptis or Listera." ("More Letters of Charles Darwin", Vol. II. page 419.) Expressions of this kind coming from a man whose theories exerted an epoch-making influence, would be unintelligible if his researches into the biology of flowers had been concerned only with records of isolated facts, however interesting these might be. We may at once take it for granted that the investigations were undertaken with the view of following up important problems of general interest, problems which are briefly dealt with in this essay. Darwin published the results of his researches in several papers and in three larger works, (i) "On the various contrivances by which British and Foreign Orchids are fertilised by insects" (First edition, London, 1862; second edition, 1877; popular edition, 1904.) (ii) "The effects of Cross and Self fertilisation in the vegetable kingdom" (First edition, 1876; second edition, 1878). (iii) "The different forms of Flowers on plants of the same species" (First edition, 1877; second edition, 1880). Although the influence of his work is considered later, we may here point out that it was almost without a parallel; not only does it include a mass of purely scientific observations, but it awakened interest in very wide circles, as is shown by the fact that we find the results of Darwin's investigations in floral biology universally quoted in school books; they are even willingly accepted by those who, as regards other questions, are opposed to Darwin's views. The works which we have mentioned are, however, not only of special interest because of the facts they contribute, but because of the MANNER in which the facts are expressed. A superficial reader seeking merely for catch-words will, for instance, probably find the book on cross and self-fertilisation rather dry because of the numerous details which it contains: it is, indeed, not easy to compress into a few words the general conclusions of this volume. But on closer examination, we cannot be sufficiently grateful to the author for the exactness and objectivity with which he enables us to participate in the scheme of his researches. He never tries to persuade us, but only to convince us that his conclusions are based on facts; he always gives prominence to such facts as appear to be in opposition to his opinions,--a feature of his work in accordance with a maxim which he laid down:--"It is a golden rule, which I try to follow, to put every fact which is opposed to one's preconceived opinion in the strongest light." ("More Letters", Vol. II. page 324.) The result of this method of presentation is that the works mentioned above represent a collection of most valuable documents even for those who feel impelled to draw from the data other conclusions than those of the author. Each investigation is the outcome of a definite question, a "preconceived opinion," which is either supported by the facts or must be abandoned. "How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service!" (Ibid. Vol. I. page 195.) The points of view which Darwin had before him were principally the following. In the first place the proof that a large number of the peculiarities in the structure of flowers are not useless, but of the greatest significance in pollination must be of considerable importance for the interpretation of adaptations; "The use of each trifling detail of structure is far from a barren search to those who believe in natural selection." ("Fertilisation of Orchids" (1st edition), page 351; (2nd edition 1904) page 286.) Further, if these structural relations are shown to be useful, they may have been acquired because from the many variations which have occurred along different lines, those have been preserved by natural selection "which are beneficial to the organism under the complex and ever-varying conditions of life." (Ibid. page 351.) But in the case of flowers there is not only the question of adaptation to fertilisation to be considered. Darwin, indeed, soon formed the opinion which he has expressed in the following sentence,--"From my own observations on plants, guided to a certain extent by the experience of the breeders of animals, I became convinced many years ago that it is a general law of nature that flowers are adapted to be crossed, at least occasionally, by pollen from a distinct plant." ("Cross and Self fertilisation" (1st edition), page 6.) The experience of animal breeders pointed to the conclusion that continual in-breeding is injurious. If this is correct, it raises the question whether the same conclusion holds for plants. As most flowers are hermaphrodite, plants afford much more favourable material than animals for an experimental solution of the question, what results follow from the union of nearly related sexual cells as compared with those obtained by the introduction of new blood. The answer to this question must, moreover, possess the greatest significance for the correct understanding of sexual reproduction in general. We see, therefore, that the problems which Darwin had before him in his researches into the biology of flowers were of the greatest importance, and at the same time that the point of view from which he attacked the problems was essentially a teleological one. We may next inquire in what condition he found the biology of flowers at the time of his first researches, which were undertaken about the year 1838. In his autobiography he writes,--"During the summer of 1839, and, I believe, during the previous summer, I was led to attend to the cross-fertilisation of flowers by the aid of insects, from having come to the conclusion in my speculations on the origin of species, that crossing played an important part in keeping specific forms constant." ("The Life and Letters of Charles Darwin", Vol. I. page 90, London, 1888.) In 1841 he became acquainted with Sprengel's work: his researches into the biology of flowers were thus continued for about forty years. It is obvious that there could only be a biology of flowers after it had been demonstrated that the formation of seeds and fruit in the flower is dependent on pollination and subsequent fertilisation. This proof was supplied at the end of the seventeenth century by R.J. Camerarius (1665-1721). He showed that normally seeds and fruits are developed only when the pollen reaches the stigma. The manner in which this happens was first thoroughly investigated by J.G. Kolreuter (1733-1806 (Kolreuter, "Vorlaufige Nachricht von einigen das Geschlecht der Planzen betreffenden Versuchen und Beobachtungen", Leipzig, 1761; with three supplements, 1763-66. Also, "Mem. de l'acad. St Petersbourg", Vol. XV. 1809.)), the same observer to whom we owe the earliest experiments in hybridisation of real scientific interest. Kolreuter mentioned that pollen may be carried from one flower to another partly by wind and partly by insects. But he held the view, and that was, indeed, the natural assumption, that self-fertilisation usually occurs in a flower, in other words that the pollen of a flower reaches the stigma of the same flower. He demonstrated, however, certain cases in which cross-pollination occurs, that is in which the pollen of another flower of the same species is conveyed to the stigma. He was familiar with the phenomenon, exhibited by numerous flowers, to which Sprengel afterwards applied the term Dichogamy, expressing the fact that the anthers and stigmas of a flower often ripen at different times, a peculiarity which is now recognised as one of the commonest means of ensuring cross-pollination. With far greater thoroughness and with astonishing power of observation C.K. Sprengel (1750-1816) investigated the conditions of pollination of flowers. Darwin was introduced by that eminent botanist Robert Brown to Sprengel's then but little appreciated work,--"Das entdeckte Geheimniss der Natur im Bau und in der Befruchtung der Blumen" (Berlin, 1793); this is by no means the least service to Botany rendered by Robert Brown. Sprengel proceeded from a naive teleological point of view. He firmly believed "that the wise Author of nature had not created a single hair without a definite purpose." He succeeded in demonstrating a number of beautiful adaptations in flowers for ensuring pollination; but his work exercised but little influence on his contemporaries and indeed for a long time after his death. It was through Darwin that Sprengel's work first achieved a well deserved though belated fame. Even such botanists as concerned themselves with researches into the biology of flowers appear to have formerly attached much less value to Sprengel's work than it has received since Darwin's time. In illustration of this we may quote C.F. Gartner whose name is rightly held in the highest esteem as that of one of the most eminent hybridologists. In his work "Versuche und Beobachtungen uder die Befruchtungsorgane der vollkommeneren Gewachse und uber die naturliche und kunstliche Befruchtung durch den eigenen Pollen" he also deals with flower-pollination. He recognised the action of the wind, but he believed, in spite of the fact that he both knew and quoted Kolreuter and Sprengel, that while insects assist pollination, they do so only occasionally, and he held that insects are responsible for the conveyance of pollen; thorough investigations would show "that a very small proportion of the plants included in this category require this assistance in their native habitat." (Gartner, "Versucher und Beobachtungen... ", page 335, Stuttgart, 1844.) In the majority of plants self-pollination occurs. Seeing that even investigators who had worked for several decades at fertilisation-phenomena had not advanced the biology of flowers beyond the initial stage, we cannot be surprised that other botanists followed to even a less extent the lines laid down by Kolreuter and Sprengel. This was in part the result of Sprengel's supernatural teleology and in part due to the fact that his book appeared at a time when other lines of inquiry exerted a dominating influence. At the hands of Linnaeus systematic botany reached a vigorous development, and at the beginning of the nineteenth century the anatomy and physiology of plants grew from small beginnings to a flourishing branch of science. Those who concerned themselves with flowers endeavoured to investigate their development and structure or the most minute phenomena connected with fertilisation and the formation of the embryo. No room was left for the extension of the biology of flowers on the lines marked out by Kolreuter and Sprengel. Darwin was the first to give new life and a deeper significance to this subject, chiefly because he took as his starting-point the above-mentioned problems, the importance of which is at once admitted by all naturalists. The further development of floral biology by Darwin is in the first place closely connected with the book on the fertilisation of Orchids. It is noteworthy that the title includes the sentence,--"and on the good effects of intercrossing." The purpose of the book is clearly stated in the introduction:--"The object of the following work is to show that the contrivances by which Orchids are fertilised, are as varied and almost as perfect as any of the most beautiful adaptations in the animal kingdom; and, secondly, to show that these contrivances have for their main object the fertilisation of each flower by the pollen of another flower." ("Fertilisation of Orchids", page 1.) Orchids constituted a particularly suitable family for such researches. Their flowers exhibit a striking wealth of forms; the question, therefore, whether the great variety in floral structure bears any relation to fertilisation (In the older botanical literature the word fertilisation is usually employed in cases where POLLINATION is really in question: as Darwin used it in this sense it is so used here.) must in this case possess special interest. Darwin succeeded in showing that in most of the orchids examined self-fertilisation is either an impossibility, or, under natural conditions, occurs only exceptionally. On the other hand these plants present a series of extraordinarily beautiful and remarkable adaptations which ensure the transference of pollen by insects from one flower to another. It is impossible to describe adequately in a few words the wealth of facts contained in the Orchid book. A few examples may, however, be quoted in illustration of the delicacy of the observations and of the perspicuity employed in interpreting the facts. The majority of orchids differ from other seed plants (with the exception of the Asclepiads) in having no dust-like pollen. The pollen, or more correctly, the pollen-tetrads, remain fastened together as club-shaped pollinia usually borne on a slender pedicel. At the base of the pedicel is a small viscid disc by which the pollinium is attached to the head or proboscis of one of the insects which visit the flower. Darwin demonstrated that in Orchis and other flowers the pedicel of the pollinium, after its removal from the anther, undergoes a curving movement. If the pollinium was originally vertical, after a time it assumed a horizontal position. In the latter position, if the insect visited another flower, the pollinium would exactly hit the sticky stigmatic surface and thus effect fertilisation. The relation between the behaviour of the viscid disc and the secretion of nectar by the flower is especially remarkable. The flowers possess a spur which in some species (e.g. Gymnadenia conopsea, Platanthera bifolia, etc.) contains honey (nectar), which serves as an attractive bait for insects, but in others (e.g. our native species of Orchis) the spur is empty. Darwin held the opinion, confirmed by later investigations, that in the case of flowers without honey the insects must penetrate the wall of the nectarless spurs in order to obtain a nectar-like substance. The glands behave differently in the nectar-bearing and in the nectarless flowers. In the former they are so sticky that they at once adhere to the body of the insect; in the nectarless flowers firm adherence only occurs after the viscid disc has hardened. It is, therefore, adaptively of value that the insects should be detained longer in the nectarless flowers (by having to bore into the spur),--than in flowers in which the nectar is freely exposed. "If this relation, on the one hand, between the viscid matter requiring some little time to set hard, and the nectar being so lodged that moths are delayed in getting it; and, on the other hand, between the viscid matter being at first as viscid as ever it will become, and the nectar lying all ready for rapid suction, be accidental, it is a fortunate accident for the plant. If not accidental, and I cannot believe it to be accidental, what a singular case of adaptation!" ("Fertilisation of Orchids" (1st edition), page 53.) Among exotic orchids Catasetum is particularly remarkable. One and the same species bears different forms of flowers. The species known as Catasetum tridentatum has pollinia with very large viscid discs; on touching one of the two filaments (antennae) which occur on the gynostemium of the flower the pollinia are shot out to a fairly long distance (as far as 1 metre) and in such manner that they alight on the back of the insect, where they are held. The antennae have, moreover, acquired an importance, from the point of view of the physiology of stimulation, as stimulus-perceiving organs. Darwin had shown that it is only a touch on the antennae that causes the explosion, while contact, blows, wounding, etc. on other places produce no effect. This form of flower proved to be the male. The second form, formerly regarded as a distinct species and named Monachanthus viridis, is shown to be the female flower. The anthers have only rudimentary pollinia and do not open; there are no antennae, but on the other hand numerous seeds are produced. Another type of flower, known as Myanthus barbatus, was regarded by Darwin as a third form: this was afterwards recognised by Rolfe (Rolfe, R.A. "On the sexual forms of Catasetum with special reference to the researches of Darwin and others," "Journ. Linn. Soc." Vol. XXVII. (Botany), 1891, pages 206-225.) as the male flower of another species, Catasetum barbatum Link, an identification in accordance with the discovery made by Cruger in Trinidad that it always remains sterile. Darwin had noticed that the flowers of Catasetum do not secrete nectar, and he conjectured that in place of it the insects gnaw a tissue in the cavity of the labellum which has a "slightly sweet, pleasant and nutritious taste." This conjecture as well as other conclusions drawn by Darwin from Catasetum have been confirmed by Cruger--assuredly the best proof of the acumen with which the wonderful floral structure of this "most remarkable of the Orchids" was interpretated far from its native habitat. As is shown by what we have said about Catasetum, other problems in addition to those concerned with fertilisation are dealt with in the Orchid book. This is especially the case in regard to flower morphology. The scope of flower morphology cannot be more clearly and better expressed than by these words: "He will see how curiously a flower may be moulded out of many separate organs--how perfect the cohesion of primordially distinct parts may become,--how organs may be used for purposes widely different from their proper function,--how other organs may be entirely suppressed, or leave mere useless emblems of their former existence." ("Fertilisation of Orchids", page 289.) In attempting, from this point of view, to refer the floral structure of orchids to their original form, Darwin employed a much more thorough method than that of Robert Brown and others. The result of this was the production of a considerable literature, especially in France, along the lines suggested by Darwin's work. This is the so-called anatomical method, which seeks to draw conclusions as to the morphology of the flower from the course of the vascular bundles in the several parts. (He wrote in one of his letters, "... the destiny of the whole human race is as nothing to the course of vessels of orchids" ("More Letters", Vol. II. page 275.) Although the interpretation of the orchid flower given by Darwin has not proved satisfactory in one particular point--the composition of the labellum--the general results have received universal assent, namely "that all Orchids owe what they have in common to descent from some monocotyledonous plant, which, like so many other plants of the same division, possessed fifteen organs arranged alternately three within three in five whorls." ("Fertilisation of Orchids" (1st edition), page 307.) The alterations which their original form has undergone have persisted so far as they were found to be of use. We see also that the remarkable adaptations of which we have given some examples are directed towards cross-fertilisation. In only a few of the orchids investigated by Darwin--other similar cases have since been described--was self-fertilisation found to occur regularly or usually. The former is the case in the Bee Ophrys (Ophrys apifera), the mechanism of which greatly surprised Darwin. He once remarked to a friend that one of the things that made him wish to live a few thousand years was his desire to see the extinction of the Bee Ophrys, an end to which he believed its self-fertilising habit was leading. ("Life and Letters", Vol. III. page 276 (footnote).) But, he wrote, "the safest conclusion, as it seems to me, is, that under certain unknown circumstances, and perhaps at very long intervals of time, one individual of the Bee Ophrys is crossed by another." ("Fertilisation of Orchids" page 71.) If, on the one hand, we remember how much more sure self-fertilisation would be than cross-fertilisation, and, on the other hand, if we call to mind the numerous contrivances for cross-fertilisation, the conclusion is naturally reached that "it is an astonishing fact that self-fertilisation should not have been an habitual occurrence. It apparently demonstrates to us that there must be something injurious in the process. Nature thus tells us, in the most emphatic manner, that she abhors perpetual self-fertilisation... For may we not further infer as probable, in accordance with the belief of the vast majority of the breeders of our domestic productions, that marriage between near relations is likewise in some way injurious, that some unknown great good is derived from the union of individuals which have been kept distinct for many generations?" (Ibid., page 359.) This view was supported by observations on plants of other families, e.g. Papilionaceae; it could, however, in the absence of experimental proof, be regarded only as a "working hypothesis." All adaptations to cross-pollination might also be of use simply because they made pollination possible when for any reason self-pollination had become difficult or impossible. Cross-pollination would, therefore, be of use, not as such, but merely as a means of pollination in general; it would to some extent serve as a remedy for a method unsuitable in itself, such as a modification standing in the way of self-pollination, and on the other hand as a means of increasing the chance of pollination in the case of flowers in which self-pollination was possible, but which might, in accidental circumstances, be prevented. It was, therefore, very important to obtain experimental proof of the conclusion to which Darwin was led by the belief of the majority of breeders and by the evidence of the widespread occurrence of cross-pollination and of the remarkable adaptations thereto. This was supplied by the researches which are described in the two other works named above. The researches on which the conclusions rest had, in part at least, been previously published in separate papers: this is the case as regards the heterostyled plants. The discoveries which Darwin made in the course of his investigations of these plants belong to the most brilliant in biological science. The case of Primula is now well known. C.K. Sprengel and others were familiar with the remarkable fact that different individuals of the European species of Primula bear differently constructed flowers; some plants possess flowers in which the styles project beyond the stamens attached to the corolla-tube (long-styled form), while in others the stamens are inserted above the stigma which is borne on a short style (short-styled form). It has been shown by Breitenbach that both forms of flower may occur on the same plant, though this happens very rarely. An analogous case is occasionally met with in hybrids, which bear flowers of different colour on the same plant (e.g. Dianthus caryophyllus). Darwin showed that the external differences are correlated with others in the structure of the stigma and in the nature of the pollen. The long-styled flowers have a spherical stigma provided with large stigmatic papillae; the pollen grains are oblong and smaller than those of the short-styled flowers. The number of the seeds produced is smaller and the ovules larger, probably also fewer in number. The short-styled flowers have a smooth compressed stigma and a corolla of somewhat different form; they produce a greater number of seeds. These different forms of flowers were regarded as merely a case of variation, until Darwin showed "that these heterostyled plants are adapted for reciprocal fertilisation; so that the two or three forms, though all are hermaphrodites, are related to one another almost like the males and females of ordinary unisexual animals." ("Forms of Flowers" (1st edition), page 2.) We have here an example of hermaphrodite flowers which are sexually different. There are essential differences in the manner in which fertilisation occurs. This may be effected in four different ways; there are two legitimate and two illegitimate types of fertilisation. The fertilisation is legitimate if pollen from the long-styled flowers reaches the stigma of the short-styled form or if pollen of the short-styled flowers is brought to the stigma of the long-styled flower, that is the organs of the same length of the two different kinds of flower react on one another. Illegitimate fertilisation is represented by the two kinds of self-fertilisation, also by cross-fertilisation, in which the pollen of the long-styled form reaches the stigma of the same type of flower and, similarly, by cross-pollination in the case of the short-styled flowers. The applicability of the terms legitimate and illegitimate depends, on the one hand, upon the fact that insects which visit the different forms of flowers pollinate them in the manner suggested; the pollen of the short-styled flowers adhere to that part of the insect's body which touches the stigma of the long-styled flower and vice versa. On the other hand, it is based also on the fact that experiment shows that artificial pollination produces a very different result according as this is legitimate or illegitimate; only the legitimate union ensures complete fertility, the plants thus produced being stronger than those which are produced illegitimately. If we take 100 as the number of flowers which produce seeds as the result of legitimate fertilisation, we obtain the following numbers from illegitimate fertilisation: Primula officinalis (P. veris) (Cowslip)... 69 Primula elatior (Oxlip).................... 27 Primula acaulis (P. vulgaris) (Primrose)... 60 Further, the plants produced by the illegitimate method of fertilisation showed, e.g. in P. officinalis, a decrease in fertility in later generations, sterile pollen and in the open a feebler growth. (Under very favourable conditions (in a greenhouse) the fertility of the plants of the fourth generation increases--a point, which in view of various theoretical questions, deserves further investigation.) They behave in fact precisely in the same way as hybrids between species of different genera. This result is important, "for we thus learn that the difficulty in sexually uniting two organic forms and the sterility of their offspring, afford no sure criterion of so-called specific distinctness" ("Forms of Flowers", page 242): the relative or absolute sterility of the illegitimate unions and that of their illegitimate descendants depend exclusively on the nature of the sexual elements and on their inability to combine in a particular manner. This functional difference of sexual cells is characteristic of the behaviour of hybrids as of the illegitimate unions of heterostyled plants. The agreement becomes even closer if we regard the Primula plants bearing different forms of flowers not as belonging to a systematic entity or "species," but as including several elementary species. The legitimately produced plants are thus true hybrids (When Darwin wrote in reference to the different forms of heterostyled plants, "which all belong to the same species as certainly as do the two sexes of the same species" ("Cross and Self fertilisation", page 466), he adopted the term species in a comprehensive sense. The recent researches of Bateson and Gregory ("On the inheritance of Heterostylism in Primula"; "Proc. Roy. Soc." Ser. B, Vol. LXXVI. 1905, page 581) appear to me also to support the view that the results of illegitimate crossing of heterostyled Primulas correspond with those of hybridisation. The fact that legitimate pollen effects fertilisation, even if illegitimate pollen reaches the stigma a short time previously, also points to this conclusion. Self-pollination in the case of the short-styled form, for example, is not excluded. In spite of this, the numerical proportion of the two forms obtained in the open remains approximately the same as when the pollination was exclusively legitimate, presumably because legitimate pollen is prepotent.), with which their behaviour in other respects, as Darwin showed, presents so close an agreement. This view receives support also from the fact that descendants of a flower fertilised illegitimately by pollen from another plant with the same form of flower belong, with few exceptions, to the same type as that of their parents. The two forms of flower, however, behave differently in this respect. Among 162 seedlings of the long-styled illegitimately pollinated plants of Primula officinalis, including five generations, there were 156 long-styled and only six short-styled forms, while as the result of legitimate fertilisation nearly half of the offspring were long-styled and half short-styled. The short-styled illegitimately pollinated form gave five long-styled and nine short-styled; the cause of this difference requires further explanation. The significance of heterostyly, whether or not we now regard it as an arrangement for the normal production of hybrids, is comprehensively expressed by Darwin: "We may feel sure that plants have been rendered heterostyled to ensure cross-fertilisation, for we now know that a cross between the distinct individuals of the same species is highly important for the vigour and fertility of the offspring." ("Forms of Flowers", page 258.) If we remember how important the interpretation of heterostyly has become in all general problems as, for example, those connected with the conditions of the formation of hybrids, a fact which was formerly overlooked, we can appreciate how Darwin was able to say in his autobiography: "I do not think anything in my scientific life has given me so much satisfaction as making out the meaning of the structure of these plants." ("Life and Letters", Vol. I. page 91.) The remarkable conditions represented in plants with three kinds of flowers, such as Lythrum and Oxalis, agree in essentials with those in Primula. These cannot be considered in detail here; it need only be noted that the investigation of these cases was still more laborious. In order to establish the relative fertility of the different unions in Lythrum salicaria 223 different fertilisations were made, each flower being deprived of its male organs and then dusted with the appropriate pollen. In the book containing the account of heterostyled plants other species are dealt with which, in addition to flowers opening normally (chasmogamous), also possess flowers which remain closed but are capable of producing fruit. These cleistogamous flowers afford a striking example of habitual self-pollination, and H. von Mohl drew special attention to them as such shortly after the appearance of Darwin's Orchid book. If it were only a question of producing seed in the simplest way, cleistogamous flowers would be the most conveniently constructed. The corolla and frequently other parts of the flower are reduced; the development of the seed may, therefore, be accomplished with a smaller expenditure of building material than in chasmogamous flowers; there is also no loss of pollen, and thus a smaller amount suffices for fertilisation. Almost all these plants, as Darwin pointed out, have also chasmogamous flowers which render cross-fertilisation possible. His view that cleistogamous flowers are derived from originally chasmogamous flowers has been confirmed by more recent researches. Conditions of nutrition in the broader sense are the factors which determine whether chasmogamous or cleistogamous flowers are produced, assuming, of course, that the plants in question have the power of developing both forms of flower. The former may fail to appear for some time, but are eventually developed under favourable conditions of nourishment. The belief of many authors that there are plants with only cleistogamous flowers cannot therefore be accepted as authoritative without thorough experimental proof, as we are concerned with extra-european plants for which it is often difficult to provide appropriate conditions in cultivation. Darwin sees in cleistogamous flowers an adaptation to a good supply of seeds with a small expenditure of material, while chasmogamous flowers of the same species are usually cross-fertilised and "their offspring will thus be invigorated, as we may infer from a wide-spread analogy." ("Forms of Flowers" (1st edition), page 341.) Direct proof in support of this has hitherto been supplied in a few cases only; we shall often find that the example set by Darwin in solving such problems as these by laborious experiment has unfortunately been little imitated. Another chapter of this book treats of the distribution of the sexes in polygamous, dioecious, and gyno-dioecious plants (the last term, now in common use, we owe to Darwin). It contains a number of important facts and discussions and has inspired the experimental researches of Correns and others. The most important of Darwin's work on floral biology is, however, that on cross and self-fertilisation, chiefly because it states the results of experimental investigations extending over many years. Only such experiments, as we have pointed out, could determine whether cross-fertilisation is in itself beneficial, and self-fertilisation on the other hand injurious; a conclusion which a merely comparative examination of pollination-mechanisms renders in the highest degree probable. Later floral biologists have unfortunately almost entirely confined themselves to observations on floral mechanisms. But there is little more to be gained by this kind of work than an assumption long ago made by C.K. Sprengel that "very many flowers have the sexes separate and probably at least as many hermaphrodite flowers are dichogamous; it would thus appear that Nature was unwilling that any flower should be fertilised by its own pollen." It was an accidental observation which inspired Darwin's experiments on the effect of cross and self-fertilisation. Plants of Linaria vulgaris were grown in two adjacent beds; in the one were plants produced by cross-fertilisation, that is, from seeds obtained after fertilisation by pollen of another plant of the same species; in the other grew plants produced by self-fertilisation, that is from seed produced as the result of pollination of the same flower. The first were obviously superior to the latter. Darwin was surprised by this observation, as he had expected a prejudicial influence of self-fertilisation to manifest itself after a series of generations: "I always supposed until lately that no evil effects would be visible until after several generations of self-fertilisation, but now I see that one generation sometimes suffices and the existence of dimorphic plants and all the wonderful contrivances of orchids are quite intelligible to me." ("More Letters", Vol. II. page 373.) The observations on Linaria and the investigations of the results of legitimate and illegitimate fertilisation in heterostyled plants were apparently the beginning of a long series of experiments. These were concerned with plants of different families and led to results which are of fundamental importance for a true explanation of sexual reproduction. The experiments were so arranged that plants were shielded from insect-visits by a net. Some flowers were then pollinated with their own pollen, others with pollen from another plant of the same species. The seeds were germinated on moist sand; two seedlings of the same age, one from a cross and the other from a self-fertilised flower, were selected and planted on opposite sides of the same pot. They grew therefore under identical external conditions; it was thus possible to compare their peculiarities such as height, weight, fruiting capacity, etc. In other cases the seedlings were placed near to one another in the open and in this way their capacity of resisting unfavourable external conditions was tested. The experiments were in some cases continued to the tenth generation and the flowers were crossed in different ways. We see, therefore, that this book also represents an enormous amount of most careful and patient original work. The general result obtained is that plants produced as the result of cross-fertilisation are superior, in the majority of cases, to those produced as the result of self-fertilisation, in height, resistance to external injurious influences, and in seed-production. Ipomoea purpurea may be quoted as an example. If we express the result of cross-fertilisation by 100, we obtain the following numbers for the fertilised plants. Generation. Height. Number of seeds. 1 100: 76 100: 64 2 100: 79 - 3 100: 68 100: 94 4 100: 86 100: 94 5 100: 75 100: 89 6 100: 72 - 7 100: 81 - 8 100: 85 - 9 100: 79 100: 26 (Number of capsules) 10 100: 54 - Taking the average, the ratio as regards growth is 100:77. The considerable superiority of the crossed plants is apparent in the first generation and is not increased in the following generations; but there is some fluctuation about the average ratio. The numbers representing the fertility of crossed and self-fertilised plants are more difficult to compare with accuracy; the superiority of the crossed plants is chiefly explained by the fact that they produce a much larger number of capsules, not because there are on the average more seeds in each capsule. The ratio of the capsules was, e.g. in the third generation, 100:38, that of the seeds in the capsules 100:94. It is also especially noteworthy that in the self-fertilised plants the anthers were smaller and contained a smaller amount of pollen, and in the eighth generation the reduced fertility showed itself in a form which is often found in hybrids, that is the first flowers were sterile. (Complete sterility was not found in any of the plants investigated by Darwin. Others appear to be more sensitive; Cluer found Zea Mais "almost sterile" after three generations of self-fertilisation. (Cf. Fruwirth, "Die Zuchtung der Landwirtschaftlichen Kulturpflanzen", Berlin, 1904, II. page 6.)) The superiority of crossed individuals is not exhibited in the same way in all plants. For example in Eschscholzia californica the crossed seedlings do not exceed the self-fertilised in height and vigour, but the crossing considerably increases the plant's capacity for flower-production, and the seedlings from such a mother-plant are more fertile. The conception implied by the term crossing requires a closer analysis. As in the majority of plants, a large number of flowers are in bloom at the same time on one and the same plant, it follows that insects visiting the flowers often carry pollen from one flower to another of the same stock. Has this method, which is spoken of as Geitonogamy, the same influence as crossing with pollen from another plant? The results of Darwin's experiments with different plants (Ipomoea purpurea, Digitalis purpurea, Mimulus luteus, Pelargonium, Origanum) were not in complete agreement; but on the whole they pointed to the conclusion that Geitonogamy shows no superiority over self-fertilisation (Autogamy). (Similarly crossing in the case of flowers of Pelargonium zonale, which belong to plants raised from cuttings from the same parent, shows no superiority over self-fertilisation.) Darwin, however, considered it possible that this may sometimes be the case. "The sexual elements in the flowers on the same plant can rarely have been differentiated, though this is possible, as flower-buds are in one sense distinct individuals, sometimes varying and differing from one another in structure or constitution." ("Cross and Self fertilisation" (1st edition), page 444.) As regards the importance of this question from the point of view of the significance of cross-fertilisation in general, it may be noted that later observers have definitely discovered a difference between the results of autogamy and geitonogamy. Gilley and Fruwirth found that in Brassica Napus, the length and weight of the fruits as also the total weight of the seeds in a single fruit were less in the case of autogamy than in geitonogamy. With Sinapis alba a better crop of seeds was obtained after geitonogamy, and in the Sugar Beet the average weight of a fruit in the case of a self-fertilised plant was 0.009 gr., from geitonogamy 0.012 gr., and on cross-fertilisation 0.013 gr. On the whole, however, the results of geitonogamy show that the favourable effects of cross-fertilisation do not depend simply on the fact that the pollen of one flower is conveyed to the stigma of another. But the plants which are crossed must in some way be different. If plants of Ipomoea purpurea (and Mimulus luteus) which have been self-fertilised for seven generations and grown under the same conditions of cultivation are crossed together, the plants so crossed would not be superior to the self-fertilised; on the other hand crossing with a fresh stock at once proves very advantageous. The favourable effect of crossing is only apparent, therefore, if the parent plants are grown under different conditions or if they belong to different varieties. "It is really wonderful what an effect pollen from a distinct seedling plant, which has been exposed to different conditions of life, has on the offspring in comparison with pollen from the same flower or from a distinct individual, but which has been long subjected to the same conditions. The subject bears on the very principle of life, which seems almost to require changes in the conditions." ("More Letters", Vol. II. page 406.) The fertility--measured by the number or weight of the seeds produced by an equal number of plants--noticed under different conditions of fertilisation may be quoted in illustration. On crossing On crossing On self- with a fresh plants of the fertilisation stock same stock Mimuleus luteus (First and ninth generation) 100 4 3 Eschscholzia californica (second generation) 100 45 40 Dianthus caryophyllus (third and fourth generation) 100 45 33 Petunia violacea 100 54 46 Crossing under very similar conditions shows, therefore, that the difference between the sexual cells is smaller and thus the result of crossing is only slightly superior to that given by self-fertilisation. Is, then, the favourable result of crossing with a foreign stock to be attributed to the fact that this belongs to another systematic entity or to the fact that the plants, though belonging to the same entity were exposed to different conditions? This is a point on which further researches must be taken into account, especially since the analysis of the systematic entities has been much more thorough than formerly. (In the case of garden plants, as Darwin to a large extent claimed, it is not easy to say whether two individuals really belong to the same variety, as they are usually of hybrid origin. In some instances (Petunia, Iberis) the fresh stock employed by Darwin possessed flowers differing in colour from those of the plant crossed with it.) We know that most of Linneaus's species are compound species, frequently consisting of a very large number of smaller or elementary species formerly included under the comprehensive term varieties. Hybridisation has in most cases affected our garden and cultivated plants so that they do not represent pure species but a mixture of species. But this consideration has no essential bearing on Darwin's point of view, according to which the nature of the sexual cells is influenced by external conditions. Even individuals growing close to one another are only apparently exposed to identical conditions. Their sexual cells may therefore be differently influenced and thus give favourable results on crossing, as "the benefits which so generally follow from a cross between two plants apparently depend on the two differing somewhat in constitution or character." As a matter of fact we are familiar with a large number of cases in which the condition of the reproductive organs is influenced by external conditions. Darwin has himself demonstrated this for self-sterile plants, that is plants in which self-fertilisation produces no result. This self-sterility is affected by climatic conditions: thus in Brazil Eschscholzia californica is absolutely sterile to the pollen of its own flowers; the descendants of Brazilian plants in Darwin's cultures were partially self-fertile in one generation and in a second generation still more so. If one has any doubt in this case whether it is a question of the condition of the style and stigma, which possibly prevents the entrance of the pollen-tube or even its development, rather than that of the actual sexual cells, in other cases there is no doubt that an influence is exerted on the latter. Janczewski (Janczewski, "Sur les antheres steriles des Groseilliers", "Bull. de l'acad. des sciences de Cracovie", June, 1908.) has recently shown that species of Ribes cultivated under unnatural conditions frequently produce a mixed (i.e. partly useless) or completely sterile pollen, precisely as happens with hybrids. There are, therefore, substantial reasons for the conclusion that conditions of life exert an influence on the sexual cells. "Thus the proposition that the benefit from cross-fertilisation depends on the plants which are crossed having been subjected during previous generations to somewhat different conditions, or to their having varied from some unknown cause as if they had been thus subjected, is securely fortified on all sides." ("Cross and Self fertilisation" (1st edition), page 444.) We thus obtain an insight into the significance of sexuality. If an occasional and slight alteration in the conditions under which plants and animals live is beneficial (Reasons for this are given by Darwin in "Variation under Domestication" (2nd edition), Vol. II. page 127.), crossing between organisms which have been exposed to different conditions becomes still more advantageous. The entire constitution is in this way influenced from the beginning, at a time when the whole organisation is in a highly plastic state. The total life-energy, so to speak, is increased, a gain which is not produced by asexual reproduction or by the union of sexual cells of plants which have lived under the same or only slightly different conditions. All the wonderful arrangements for cross-fertilisation now appear to be useful adaptations. Darwin was, however, far from giving undue prominence to this point of view, though this has been to some extent done by others. He particularly emphasised the following consideration:--"But we should always keep in mind that two somewhat opposed ends have to be gained; the first and more important one being the production of seeds by any means, and the second, cross-fertilisation." ("Cross and Self fertilisation" (1st edition), page 371.) Just as in some orchids and cleistogamic flowers self-pollination regularly occurs, so it may also occur in other cases. Darwin showed that Pisum sativum and Lathyrus odoratus belong to plants in which self-pollination is regularly effected, and that this accounts for the constancy of certain sorts of these plants, while a variety of form is produced by crossing. Indeed among his culture plants were some which derived no benefit from crossing. Thus in the sixth self-fertilised generation of his Ipomoea cultures the "Hero" made its appearance, a form slightly exceeding its crossed companion in height; this was in the highest degree self-fertile and handed on its characteristics to both children and grandchildren. Similar forms were found in Mimulus luteus and Nicotiana (In Pisum sativum also the crossing of two individuals of the same variety produced no advantage; Darwin attributed this to the fact that the plants had for several generations been self-fertilised and in each generation cultivated under almost the same conditions. Tschermak ("Ueber kunstliche Kreuzung an Pisum sativum") afterwards recorded the same result; but he found on crossing different varieties that usually there was no superiority as regards height over the products of self-fertilisation, while Darwin found a greater height represented by the ratios 100:75 and 100:60.), types which, after self-fertilisation, have an enhanced power of seed-production and of attaining a greater height than the plants of the corresponding generation which are crossed together and self-fertilised and grown under the same conditions. "Some observations made on other plants lead me to suspect that self-fertilisation is in some respects beneficial; although the benefit thus derived is as a rule very small compared with that from a cross with a distinct plant." ("Cross and Self fertilisation", page 350.) We are as ignorant of the reason why plants behave differently when crossed and self-fertilised as we are in regard to the nature of the differentiation of the sexual cells, which determines whether a union of the sexual cells will prove favourable or unfavourable. It is impossible to discuss the different results of cross-fertilisation; one point must, however, be emphasised, because Darwin attached considerable importance to it. It is inevitable that pollen of different kinds must reach the stigma. It was known that pollen of the same "species" is dominant over the pollen of another species, that, in other words, it is prepotent. Even if the pollen of the same species reaches the stigma rather later than that of another species, the latter does not effect fertilisation. Darwin showed that the fertilising power of the pollen of another variety or of another individual is greater than that of the plant's own pollen. ("Cross and Self fertilisation", page 391.) This has been demonstrated in the case of Mimulus luteus (for the fixed white-flowering variety) and Iberis umbellata with pollen of another variety, and observations on cultivated plants, such as cabbage, horseradish, etc. gave similar results. It is, however, especially remarkable that pollen of another individual of the same variety may be prepotent over the plant's own pollen. This results from the superiority of plants crossed in this manner over self-fertilised plants. "Scarcely any result from my experiments has surprised me so much as this of the prepotency of pollen from a distinct individual over each plant's own pollen, as proved by the greater constitutional vigour of the crossed seedlings." (Ibid. page 397.) Similarly, in self-fertile plants the flowers of which have not been deprived of the male organs, pollen brought to the stigma by the wind or by insects from another plant effects fertilisation, even if the plant's own pollen has reached the stigma somewhat earlier. Have the results of his experimental investigations modified the point of view from which Darwin entered on his researches, or not? In the first place the question is, whether or not the opinion expressed in the Orchid book that there is "Something injurious" connected with self-fertilisation, has been confirmed. We can, at all events, affirm that Darwin adhered in essentials to his original position; but self-fertilisation afterwards assumed a greater importance than it formerly possessed. Darwin emphasised the fact that "the difference between the self-fertilised and crossed plants raised by me cannot be attributed to the superiority of the crossed, but to the inferiority of the self-fertilised seedlings, due to the injurious effects of self-fertilisation." (Ibid. page 437.) But he had no doubt that in favourable circumstances self-fertilised plants were able to persist for several generations without crossing. An occasional crossing appears to be useful but not indispensable in all cases; its sporadic occurrence in plants in which self-pollination habitually occurs is not excluded. Self-fertilisation is for the most part relatively and not absolutely injurious and always better than no fertilisation. "Nature abhors perpetual self-fertilisation" (It is incorrect to say, as a writer has lately said, that the aphorism expressed by Darwin in 1859 and 1862, "Nature abhors perpetual self-fertilisation," is not repeated in his later works. The sentence is repeated in "Cross and Self fertilisation" (page 8), with the addition, "If the word perpetual had been omitted, the aphorism would have been false. As it stands, I believe that it is true, though perhaps rather too strongly expressed.") is, however, a pregnant expression of the fact that cross-fertilisation is exceedingly widespread and has been shown in the majority of cases to be beneficial, and that in those plants in which we find self-pollination regularly occurring cross-pollination may occasionally take place. An attempt has been made to express in brief the main results of Darwin's work on the biology of flowers. We have seen that his object was to elucidate important general questions, particularly the question of the significance of sexual reproduction. It remains to consider what influence his work has had on botanical science. That this influence has been very considerable, is shown by a glance at the literature on the biology of flowers published since Darwin wrote. Before the book on orchids was published there was nothing but the old and almost forgotten works of Kolreuter and Sprengel with the exception of a few scattered references. Darwin's investigations gave the first stimulus to the development of an extensive literature on floral biology. In Knuth's "Handbuch der Blutenbiologie" ("Handbook of Flower Pollination", Oxford, 1906) as many as 3792 papers on this subject are enumerated as having been published before January 1, 1904. These describe not only the different mechanisms of flowers, but deal also with a series of remarkable adaptations in the pollinating insects. As a fertilising rain quickly calls into existence the most varied assortment of plants on a barren steppe, so activity now reigns in a field which men formerly left deserted. This development of the biology of flowers is of importance not only on theoretical grounds but also from a practical point of view. The rational breeding of plants is possible only if the flower-biology of the plants in question (i.e. the question of the possibility of self-pollination, self-sterility, etc.) is accurately known. And it is also essential for plant-breeders that they should have "the power of fixing each fleeting variety of colour, if they will fertilise the flowers of the desired kind with their own pollen for half-a-dozen generations, and grow the seedlings under the same conditions." ("Cross and Self fertilisation" (1st edition), page 460.) But the influence of Darwin on floral biology was not confined to the development of this branch of Botany. Darwin's activity in this domain has brought about (as Asa Gray correctly pointed out) the revival of teleology in Botany and Zoology. Attempts were now made to determine, not only in the case of flowers but also in vegetative organs, in what relation the form and function of organs stand to one another and to what extent their morphological characters exhibit adaptation to environment. A branch of Botany, which has since been called Ecology (not a very happy term) has been stimulated to vigorous growth by floral biology. While the influence of the work on the biology of flowers was extraordinarily great, it could not fail to elicit opinions at variance with Darwin's conclusions. The opposition was based partly on reasons valueless as counterarguments, partly on problems which have still to be solved; to some extent also on that tendency against teleological conceptions which has recently become current. This opposing trend of thought is due to the fact that many biologists are content with teleological explanations, unsupported by proof; it is also closely connected with the fact that many authors estimate the importance of natural selection less highly than Darwin did. We may describe the objections which are based on the widespread occurrence of self-fertilisation and geitonogamy as of little importance. Darwin did not deny the occurrence of self-fertilisation, even for a long series of generations; his law states only that "Nature abhors PERPETUAL self-fertilisation." (It is impossible (as has been attempted) to express Darwin's point of view in a single sentence, such as H. Muller's statement of the "Knight-Darwin law." The conditions of life in organisms are so various and complex that laws, such as are formulated in physics and chemistry, can hardly be conceived.) An exception to this rule would therefore occur only in the case of plants in which the possibility of cross-pollination is excluded. Some of the plants with cleistogamous flowers might afford examples of such cases. We have already seen, however, that such a case has not as yet been shown to occur. Burck believed that he had found an instance in certain tropical plants (Anonaceae, Myrmecodia) of the complete exclusion of cross-fertilisation. The flowers of these plants, in which, however,--in contrast to the cleistogamous flowers--the corolla is well developed, remain closed and fruit is produced. Loew (E. Loew, "Bemerkungen zu Burck... ", "Biolog. Centralbl." XXVI. (1906).) has shown that cases occur in which cross-fertilisation may be effected even in these "cleistopetalous" flowers: humming birds visit the permanently closed flowers of certain species of Nidularium and transport the pollen. The fact that the formation of hybrids may occur as the result of this shows that pollination may be accomplished. The existence of plants for which self-pollination is of greater importance than it is for others is by no means contradictory to Darwin's view. Self-fertilisation is, for example, of greater importance for annuals than for perennials as without it seeds might fail to be produced. Even in the case of annual plants with small inconspicuous flowers in which self-fertilisation usually occurs, such as Senecio vulgaris, Capsella bursa-pastoris and Stellaria media, A. Bateson (Anna Bateson, "The effects of cross-fertilisation on inconspicuous flowers", "Annals of Botany", Vol. I. 1888, page 255.) found that cross-fertilisation gave a beneficial result, although only in a slight degree. If the favourable effects of sexual reproduction, according to Darwin's view, are correlated with change of environment, it is quite possible that this is of less importance in plants which die after ripening their seeds ("hapaxanthic") and which in any case constantly change their situation. Objections which are based on the proof of the prevalence of self-fertilisation are not, therefore, pertinent. At first sight another point of view, which has been more recently urged, appears to have more weight. W. Burck (Burck, "Darwin's Kreuzeungsgesetz... ", "Biol. Centralbl". XXVIII. 1908, page 177.) has expressed the opinion that the beneficial results of cross-fertilisation demonstrated by Darwin concern only hybrid plants. These alone become weaker by self-pollination; while pure species derive no advantage from crossing and no disadvantage from self-fertilisation. It is certain that some of the plants used by Darwin were of hybrid origin. (It is questionable if this was always the case.) This is evident from his statements, which are models of clearness and precision; he says that his Ipomoea plants "were probably the offspring of a cross." ("Cross and Self fertilisation" (1st edition), page 55.) The fixed forms of this plant, such as Hero, which was produced by self-fertilisation, and a form of Mimulus with white flowers spotted with red probably resulted from splitting of the hybrids. It is true that the phenomena observed in self-pollination, e.g. in Ipomoea, agree with those which are often noticed in hybrids; Darwin himself drew attention to this. Let us next call to mind some of the peculiarities connected with hybridisation. We know that hybrids are often characterized by their large size, rapidity of growth, earlier production of flowers, wealth of flower-production and a longer life; hybrids, if crossed with one of the two parent forms, are usually more fertile than when they are crossed together or with another hybrid. But the characters which hybrids exhibit on self-fertilisation are rather variable. The following instance may be quoted from Gartner: "There are many hybrids which retain the self-fertility of the first generation during the second and later generations, but very often in a less degree; a considerable number, however, become sterile." But the hybrid varieties may be more fertile in the second generation than in the first, and in some hybrids the fertility with their own pollen increases in the second, third, and following generations. (K.F. Gartner, "Versuche uber die Bastarderzeugung", Stuttgart, 1849, page 149.) As yet it is impossible to lay down rules of general application for the self-fertility of hybrids. That the beneficial influence of crossing with a fresh stock rests on the same ground--a union of sexual cells possessing somewhat different characters--as the fact that many hybrids are distinguished by greater luxuriance, wealth of flowers, etc. corresponds entirely with Darwin's conclusions. It seems to me to follow clearly from his investigations that there is no essential difference between cross-fertilisation and hybridisation. The heterostyled plants are normally dependent on a process corresponding to hybridisation. The view that specifically distinct species could at best produce sterile hybrids was always opposed by Darwin. But if the good results of crossing were EXCLUSIVELY dependent on the fact that we are concerned with hybrids, there must then be a demonstration of two distinct things. First, that crossing with a fresh stock belonging to the same systematic entity or to the same hybrid, but cultivated for a considerable time under different conditions, shows no superiority over self-fertilisation, and that in pure species crossing gives no better results than self-pollination. If this were the case, we should be better able to understand why in one plant crossing is advantageous while in others, such as Darwin's Hero and the forms of Mimulus and Nicotiana no advantage is gained; these would then be pure species. But such a proof has not been supplied; the inference drawn from cleistogamous and cleistopetalous plants is not supported by evidence, and the experiments on geitonogamy and on the advantage of cross-fertilisation in species which are usually self-fertilised are opposed to this view. There are still but few researches on this point; Darwin found that in Ononis minutissima, which produces cleistogamous as well as self-fertile chasmogamous flowers, the crossed and self-fertilised capsules produced seed in the proportion of 100:65 and that the average bore the proportion 100:86. Facts previously mentioned are also applicable to this case. Further, it is certain that the self-sterility exhibited by many plants has nothing to do with hybridisation. Between self-sterility and reduced fertility as the result of self-fertilisation there is probably no fundamental difference. It is certain that so difficult a problem as that of the significance of sexual reproduction requires much more investigation. Darwin was anything but dogmatic and always ready to alter an opinion when it was not based on definite proof: he wrote, "But the veil of secrecy is as yet far from lifted; nor will it be, until we can say why it is beneficial that the sexual elements should be differentiated to a certain extent, and why, if the differentiation be carried still further, injury follows." He has also shown us the way along which to follow up this problem; it is that of carefully planned and exact experimental research. It may be that eventually many things will be viewed in a different light, but Darwin's investigations will always form the foundation of Floral Biology on which the future may continue to build. XXI. MENTAL FACTORS IN EVOLUTION. By C. Lloyd Morgan, LL.D., F.R.S. In developing his conception of organic evolution Charles Darwin was of necessity brought into contact with some of the problems of mental evolution. In "The Origin of Species" he devoted a chapter to "the diversities of instinct and of the other mental faculties in animals of the same class." ("Origin of Species" (6th edition), page 205.) When he passed to the detailed consideration of "The Descent of Man", it was part of his object to show "that there is no fundamental difference between man and the higher mammals in their mental faculties." ("Descent of Man" (2nd edition 1888), Vol. I. page 99; Popular edition page 99.) "If no organic being excepting man," he said, "had possessed any mental power, or if his powers had been of a wholly different nature from those of the lower animals, then we should never have been able to convince ourselves that our high faculties had been gradually developed." (Ibid. page 99.) In his discussion of "The Expression of the Emotions" it was important for his purpose "fully to recognise that actions readily become associated with other actions and with various states of the mind." ("The Expression of the Emotions" (2nd edition), page 32.) His hypothesis of sexual selection is largely dependent upon the exercise of choice on the part of the female and her preference for "not only the more attractive but at the same time the more vigorous and victorious males." ("Descent of Man", Vol. II. page 435.) Mental processes and physiological processes were for Darwin closely correlated; and he accepted the conclusion "that the nervous system not only regulates most of the existing functions of the body, but has indirectly influenced the progressive development of various bodily structures and of certain mental qualities." (Ibid. pages 437, 438.) Throughout his treatment, mental evolution was for Darwin incidental to and contributory to organic evolution. For specialised research in comparative and genetic psychology, as an independent field of investigation, he had neither the time nor the requisite training. None the less his writings and the spirit of his work have exercised a profound influence on this department of evolutionary thought. And, for those who follow Darwin's lead, mental evolution is still in a measure subservient to organic evolution. Mental processes are the accompaniments or concomitants of the functional activity of specially differentiated parts of the organism. They are in some way dependent on physiological and physical conditions. But though they are not physical in their nature, and though it is difficult or impossible to conceive that they are physical in their origin, they are, for Darwin and his followers, factors in the evolutionary process in its physical or organic aspect. By the physiologist within his special and well-defined universe of discourse they may be properly regarded as epiphenomena; but by the naturalist in his more catholic survey of nature they cannot be so regarded, and were not so regarded by Darwin. Intelligence has contributed to evolution of which it is in a sense a product. The facts of observation or of inference which Darwin accepted are these: Conscious experience accompanies some of the modes of animal behaviour; it is concomitant with certain physiological processes; these processes are the outcome of development in the individual and evolution in the race; the accompanying mental processes undergo a like development. Into the subtle philosophical questions which arise out of the naive acceptance of such a creed it was not Darwin's province to enter; "I have nothing to do," he said ("Origin of Species" (6th edition), page 205.), "with the origin of the mental powers, any more than I have with that of life itself." He dealt with the natural history of organisms, including not only their structure but their modes of behaviour; with the natural history of the states of consciousness which accompany some of their actions; and with the relation of behaviour to experience. We will endeavour to follow Darwin in his modesty and candour in making no pretence to give ultimate explanations. But we must note one of the implications of this self-denying ordinance of science. Development and evolution imply continuity. For Darwin and his followers the continuity is organic through physical heredity. Apart from speculative hypothesis, legitimate enough in its proper place but here out of court, we know nothing of continuity of mental evolution as such: consciousness appears afresh in each succeeding generation. Hence it is that for those who follow Darwin's lead, mental evolution is and must ever be, within his universe of discourse, subservient to organic evolution. Only in so far as conscious experience, or its neural correlate, effects some changes in organic structure can it influence the course of heredity; and conversely only in so far as changes in organic structure are transmitted through heredity, is mental evolution rendered possible. Such is the logical outcome of Darwin's teaching. Those who abide by the cardinal results of this teaching are bound to regard all behaviour as the expression of the functional activities of the living tissues of the organism, and all conscious experience as correlated with such activities. For the purposes of scientific treatment, mental processes are one mode of expression of the same changes of which the physiological processes accompanying behaviour are another mode of expression. This is simply accepted as a fact which others may seek to explain. The behaviour itself is the adaptive application of the energies of the organism; it is called forth by some form of presentation or stimulation brought to bear on the organism by the environment. This presentation is always an individual or personal matter. But in order that the organism may be fitted to respond to the presentation of the environment it must have undergone in some way a suitable preparation. According to the theory of evolution this preparation is primarily racial and is transmitted through heredity. Darwin's main thesis was that the method of preparation is predominantly by natural selection. Subordinate to racial preparation, and always dependent thereon, is individual or personal preparation through some kind of acquisition; of which the guidance of behaviour through individually won experience is a typical example. We here introduce the mental factor because the facts seem to justify the inference. Thus there are some modes of behaviour which are wholly and solely dependent upon inherited racial preparation; there are other modes of behaviour which are also dependent, in part at least, on individual preparation. In the former case the behaviour is adaptive on the first occurrence of the appropriate presentation; in the latter case accommodation to circumstances is only reached after a greater or less amount of acquired organic modification of structure, often accompanied (as we assume) in the higher animals by acquired experience. Logically and biologically the two classes of behaviour are clearly distinguishable: but the analysis of complex cases of behaviour where the two factors cooperate, is difficult and requires careful and critical study of life-history. The foundations of the mental life are laid in the conscious experience that accompanies those modes of behaviour, dependent entirely on racial preparation, which may broadly be described as instinctive. In the eighth chapter of "The Origin of Species" Darwin says ("Origin of Species" (6th edition), page 205.), "I will not attempt any definition of instinct... Every one understands what is meant, when it is said that instinct impels the cuckoo to migrate and to lay her eggs in other birds' nests. An action, which we ourselves require experience to enable us to perform, when performed by an animal, more especially by a very young one, without experience, and when performed by many individuals in the same way, without their knowing for what purpose it is performed, is usually said to be instinctive." And in the summary at the close of the chapter he says ("Origin of Species" (6th edition), page 233.), "I have endeavoured briefly to show that the mental qualities of our domestic animals vary, and that the variations are inherited. Still more briefly I have attempted to show that instincts vary slightly in a state of nature. No one will dispute that instincts are of the highest importance to each animal. Therefore there is no real difficulty, under changing conditions of life, in natural selection accumulating to any extent slight modifications of instinct which are in any way useful. In many cases habit or use and disuse have probably come into play." Into the details of Darwin's treatment there is neither space nor need to enter. There are some ambiguous passages; but it may be said that for him, as for his followers to-day, instinctive behaviour is wholly the result of racial preparation transmitted through organic heredity. For the performance of the instinctive act no individual preparation under the guidance of personal experience is necessary. It is true that Darwin quotes with approval Huber's saying that "a little dose of judgment or reason often comes into play, even with animals low in the scale of nature." (Ibid. page 205.) But we may fairly interpret his meaning to be that in behaviour, which is commonly called instinctive, some element of intelligent guidance is often combined. If this be conceded the strictly instinctive performance (or part of the performance) is the outcome of heredity and due to the direct transmission of parental or ancestral aptitudes. Hence the instinctive response as such depends entirely on how the nervous mechanism has been built up through heredity; while intelligent behaviour, or the intelligent factor in behaviour, depends also on how the nervous mechanism has been modified and moulded by use during its development and concurrently with the growth of individual experience in the customary situations of daily life. Of course it is essential to the Darwinian thesis that what Sir E. Ray Lankester has termed "educability," not less than instinct, is hereditary. But it is also essential to the understanding of this thesis that the differentiae of the hereditary factors should be clearly grasped. For Darwin there were two modes of racial preparation, (1) natural selection, and (2) the establishment of individually acquired habit. He showed that instincts are subject to hereditary variation; he saw that instincts are also subject to modification through acquisition in the course of individual life. He believed that not only the variations but also, to some extent, the modifications are inherited. He therefore held that some instincts (the greater number) are due to natural selection but that others (less numerous) are due, or partly due, to the inheritance of acquired habits. The latter involve Lamarckian inheritance, which of late years has been the centre of so much controversy. It is noteworthy however that Darwin laid especial emphasis on the fact that many of the most typical and also the most complex instincts--those of neuter insects--do not admit of such an interpretation. "I am surprised," he says ("Origin of Species" (6th edition), page 233.), "that no one has hitherto advanced this demonstrative case of neuter insects, against the well-known doctrine of inherited habit, as advanced by Lamarck." None the less Darwin admitted this doctrine as supplementary to that which was more distinctively his own--for example in the case of the instincts of domesticated animals. Still, even in such cases, "it may be doubted," he says (Ibid. pages 210, 211.), "whether any one would have thought of training a dog to point, had not some one dog naturally shown a tendency in this line... so that habit and some degree of selection have probably concurred in civilising by inheritance our dogs." But in the interpretation of the instincts of domesticated animals, a more recently suggested hypothesis, that of organic selection (Independently suggested, on somewhat different lines, by Profs. J. Mark Baldwin, Henry F. Osborn and the writer.), may be helpful. According to this hypothesis any intelligent modification of behaviour which is subject to selection is probably coincident in direction with an inherited tendency to behave in this fashion. Hence in such behaviour there are two factors: (1) an incipient variation in the line of such behaviour, and (2) an acquired modification by which the behaviour is carried further along the same line. Under natural selection those organisms in which the two factors cooperate are likely to survive. Under artificial selection they are deliberately chosen out from among the rest. Organic selection has been termed a compromise between the more strictly Darwinian and the Lamarckian principles of interpretation. But it is not in any sense a compromise. The principle of interpretation of that which is instinctive and hereditary is wholly Darwinian. It is true that some of the facts of observation relied upon by Lamarckians are introduced. For Lamarckians however the modifications which are admittedly factors in survival, are regarded as the parents of inherited variations; for believers in organic selection they are only the foster parents or nurses. It is because organic selection is the direct outcome of and a natural extension of Darwin's cardinal thesis that some reference to it here is justifiable. The matter may be put with the utmost brevity as follows. (1) Variations (V) occur, some of which are in the direction of increased adaptation (+), others in the direction of decreased adaptation (-). (2) Acquired modifications (M) also occur. Some of these are in the direction of increased accommodation to circumstances (+), while others are in the direction of diminished accommodation (-). Four major combinations are (a) + V with + M, (b) + V with - M, (c) - V with + M, (d) - V with - M. Of these (d) must inevitably be eliminated while (a) are selected. The predominant survival of (a) entails the survival of the adaptive variations which are inherited. The contributory acquisitions (+M) are not inherited; but they are none the less factors in determining the survival of the coincident variations. It is surely abundantly clear that this is Darwinism and has no tincture of Lamarck's essential principle, the inheritance of acquired characters. Whether Darwin himself would have accepted this interpretation of some at least of the evidence put forward by Lamarckians is unfortunately a matter of conjecture. The fact remains that in his interpretation of instinct and in allied questions he accepted the inheritance of individually acquired modifications of behaviour and structure. Darwin was chiefly concerned with instinct from the biological rather than from the psychological point of view. Indeed it must be confessed that, from the latter standpoint, his conception of instinct as a "mental faculty" which "impels" an animal to the performance of certain actions, scarcely affords a satisfactory basis for genetic treatment. To carry out the spirit of Darwin's teaching it is necessary to link more closely biological and psychological evolution. The first step towards this is to interpret the phenomena of instinctive behaviour in terms of stimulation and response. It may be well to take a particular case. Swimming on the part of a duckling is, from the biological point of view, a typical example of instinctive behaviour. Gently lower a recently hatched bird into water: coordinated movements of the limbs follow in rhythmical sequence. The behaviour is new to the individual though it is no doubt closely related to that of walking, which is no less instinctive. There is a group of stimuli afforded by the "presentation" which results from partial immersion: upon this there follows as a complex response an application of the functional activities in swimming; the sequence of adaptive application on the appropriate presentation is determined by racial preparation. We know, it is true, but little of the physiological details of what takes place in the central nervous system; but in broad outline the nature of the organic mechanism and the manner of its functioning may at least be provisionally conjectured in the present state of physiological knowledge. Similarly in the case of the pecking of newly-hatched chicks; there is a visual presentation, there is probably a cooperating group of stimuli from the alimentary tract in need of food, there is an adaptive application of the activities in a definite mode of behaviour. Like data are afforded in a great number of cases of instinctive procedure, sometimes occurring very early in life, not infrequently deferred until the organism is more fully developed, but all of them dependent upon racial preparation. No doubt there is some range of variation in the behaviour, just such variation as the theory of natural selection demands. But there can be no question that the higher animals inherit a bodily organisation and a nervous system, the functional working of which gives rise to those inherited modes of behaviour which are termed instinctive. It is to be noted that the term "instinctive" is here employed in the adjectival form as a descriptive heading under which may be grouped many and various modes of behaviour due to racial preparation. We speak of these as inherited; but in strictness what is transmitted through heredity is the complex of anatomical and physiological conditions under which, in appropriate circumstances, the organism so behaves. So far the term "instinctive" has a restricted biological connotation in terms of behaviour. But the connecting link between biological evolution and psychological evolution is to be sought,--as Darwin fully realised,--in the phenomena of instinct, broadly considered. The term "instinctive" has also a psychological connotation. What is that connotation? Let us take the case of the swimming duckling or the pecking chick, and fix our attention on the first instinctive performance. Grant that just as there is, strictly speaking, no inherited behaviour, but only the conditions which render such behaviour under appropriate circumstances possible; so too there is no inherited experience, but only the conditions which render such experience possible; then the cerebral conditions in both cases are the same. The biological behaviour-complex, including the total stimulation and the total response with the intervening or resultant processes in the sensorium, is accompanied by an experience-complex including the initial stimulation-consciousness and resulting response-consciousness. In the experience-complex are comprised data which in psychological analysis are grouped under the headings of cognition, affective tone and conation. But the complex is probably experienced as an unanalysed whole. If then we use the term "instinctive" so as to comprise all congenital modes of behaviour which contribute to experience, we are in a position to grasp the view that the net result in consciousness constitutes what we may term the primary tissue of experience. To the development of this experience each instinctive act contributes. The nature and manner of organisation of this primary tissue of experience are dependent on inherited biological aptitudes; but they are from the outset onwards subject to secondary development dependent on acquired aptitudes. Biological values are supplemented by psychological values in terms of satisfaction or the reverse. In our study of instinct we have to select some particular phase of animal behaviour and isolate it so far as is possible from the life of which it is a part. But the animal is a going concern, restlessly active in many ways. Many instinctive performances, as Darwin pointed out ("Origin of Species" (6th edition), page 206.), are serial in their nature. But the whole of active life is a serial and coordinated business. The particular instinctive performance is only an episode in a life-history, and every mode of behaviour is more or less closely correlated with other modes. This coordination of behaviour is accompanied by a correlation of the modes of primary experience. We may classify the instinctive modes of behaviour and their accompanying modes of instinctive experience under as many heads as may be convenient for our purposes of interpretation, and label them instincts of self-preservation, of pugnacity, of acquisition, the reproductive instincts, the parental instincts, and so forth. An instinct, in this sense of the term (for example the parental instinct), may be described as a specialised part of the primary tissue of experience differentiated in relation to some definite biological end. Under such an instinct will fall a large number of particular and often well-defined modes of behaviour, each with its own peculiar mode of experience. It is no doubt exceedingly difficult as a matter of observation and of inference securely based thereon to distinguish what is primary from what is in part due to secondary acquisition--a fact which Darwin fully appreciated. Animals are educable in different degrees; but where they are educable they begin to profit by experience from the first. Only, therefore, on the occasion of the first instinctive act of a given type can the experience gained be weighed as WHOLLY primary; all subsequent performance is liable to be in some degree, sometimes more, sometimes less, modified by the acquired disposition which the initial behaviour engenders. But the early stages of acquisition are always along the lines predetermined by instinctive differentiation. It is the task of comparative psychology to distinguish the primary tissue of experience from its secondary and acquired modifications. We cannot follow up the matter in further detail. It must here suffice to suggest that this conception of instinct as a primary form of experience lends itself better to natural history treatment than Darwin's conception of an impelling force, and that it is in line with the main trend of Darwin's thought. In a characteristic work,--characteristic in wealth of detail, in closeness and fidelity of observation, in breadth of outlook, in candour and modesty,--Darwin dealt with "The Expression of the Emotions in Man and Animals". Sir Charles Bell in his "Anatomy of Expression" had contended that many of man's facial muscles had been specially created for the sole purpose of being instrumental in the expression of his emotions. Darwin claimed that a natural explanation, consistent with the doctrine of evolution, could in many cases be given and would in other cases be afforded by an extension of the principles he advocated. "No doubt," he said ("Expression of the Emotions", page 13. The passage is here somewhat condensed.), "as long as man and all other animals are viewed as independent creations, an effectual stop is put to our natural desire to investigate as far as possible the causes of Expression. By this doctrine, anything and everything can be equally well explained... With mankind, some expressions... can hardly be understood, except on the belief that man once existed in a much lower and animal-like condition. The community of certain expressions in distinct though allied species... is rendered somewhat more intelligible, if we believe in their descent from a common progenitor. He who admits on general grounds that the structure and habits of all animals have been gradually evolved, will look at the whole subject of Expression in a new and interesting light." Darwin relied on three principles of explanation. "The first of these principles is, that movements which are serviceable in gratifying some desire, or in relieving some sensation, if often repeated, become so habitual that they are performed, whether or not of any service, whenever the same desire or sensation is felt, even in a very weak degree." (Ibid. page 368.) The modes of expression which fall under this head have become instinctive through the hereditary transmission of acquired habit. "As far as we can judge, only a few expressive movements are learnt by each individual; that is, were consciously and voluntarily performed during the early years of life for some definite object, or in imitation of others, and then became habitual. The far greater number of the movements of expression, and all the more important ones, are innate or inherited; and such cannot be said to depend on the will of the individual. Nevertheless, all those included under our first principle were at first voluntarily performed for a definite object,--namely, to escape some danger, to relieve some distress, or to gratify some desire." (Ibid. pages 373, 374.) "Our second principle is that of antithesis. The habit of voluntarily performing opposite movements under opposite impulses has become firmly established in us by the practice of our whole lives. Hence, if certain actions have been regularly performed, in accordance with our first principle, under a certain frame of mind, there will be a strong and involuntary tendency to the performance of directly opposite actions, whether or not these are of any use, under the excitement of an opposite frame of mind." ("Expression of the Emotions", page 368.) This principle of antithesis has not been widely accepted. Nor is Darwin's own position easy to grasp. "Our third principle," he says (Ibid. page 369.), "is the direct action of the excited nervous system on the body, independently of the will, and independently, in large part, of habit. Experience shows that nerve-force is generated and set free whenever the cerebro-spinal system is excited. The direction which this nerve-force follows is necessarily determined by the lines of connection between the nerve-cells, with each other and with various parts of the body." Lack of space prevents our following up the details of Darwin's treatment of expression. Whether we accept or do not accept his three principles of explanation we must regard his work as a masterpiece of descriptive analysis, packed full of observations possessing lasting value. For a further development of the subject it is essential that the instinctive factors in expression should be more fully distinguished from those which are individually acquired--a difficult task--and that the instinctive factors should be rediscussed in the light of modern doctrines of heredity, with a view to determining whether Lamarckian inheritance, on which Darwin so largely relied, is necessary for an interpretation of the facts. The whole subject as Darwin realised is very complex. Even the term "expression" has a certain amount of ambiguity. When the emotion is in full flood the animal fights, flees, or faints. Is this full-tide effect to be regarded as expression; or are we to restrict the term to the premonitory or residual effects--the bared canine when the fighting mood is being roused, the ruffled fur when reminiscent representations of the object inducing anger cross the mind? Broadly considered both should be included. The activity of premonitory expression as a means of communication was recognised by Darwin; he might, perhaps, have emphasised it more strongly in dealing with the lower animals. Man so largely relies on a special means of communication, that of language, that he sometimes fails to realise that for animals with their keen powers of perception, and dependent as they are on such means of communication, the more strictly biological means of expression are full of subtle suggestiveness. Many modes of expression, otherwise useless, are signs of behaviour that may be anticipated,--signs which stimulate the appropriate attitude of response. This would not, however, serve to account for the utility of the organic accompaniments--heart-affection, respiratory changes, vaso-motor effects and so forth, together with heightened muscular tone,--on all of which Darwin lays stress ("Expression of the Emotions", pages 65 ff.) under his third principle. The biological value of all this is, however, of great importance, though Darwin was hardly in a position to take it fully into account. Having regard to the instinctive and hereditary factors of emotional expression we may ask whether Darwin's third principle does not alone suffice as an explanation. Whether we admit or reject Lamarckian inheritance it would appear that all hereditary expression must be due to pre-established connections within the central nervous system and to a transmitted provision for coordinated response under the appropriate stimulation. If this be so, Darwin's first and second principles are subordinate and ancillary to the third, an expression, so far as it is instinctive or hereditary, being "the direct result of the constitution of the nervous system." Darwin accepted the emotions themselves as hereditary or acquired states of mind and devoted his attention to their expression. But these emotions themselves are genetic products and as such dependent on organic conditions. It remained, therefore, for psychologists who accepted evolution and sought to build on biological foundations to trace the genesis of these modes of animal and human experience. The subject has been independently developed by Professors Lange and James (Cf. William James, "Principles of Psychology", Vol. II. Chap. XXV, London, 1890.); and some modification of their view is regarded by many evolutionists as affording the best explanation of the facts. We must fix our attention on the lower emotions, such as anger or fear, and on their first occurrence in the life of the individual organism. It is a matter of observation that if a group of young birds which have been hatched in an incubator are frightened by an appropriate presentation, auditory or visual, they instinctively respond in special ways. If we speak of this response as the expression, we find that there are many factors. There are certain visible modes of behaviour, crouching at once, scattering and then crouching, remaining motionless, the braced muscles sustaining an attitude of arrest, and so forth. There are also certain visceral or organic effects, such as affections of the heart and respiration. These can be readily observed by taking the young bird in the hand. Other effects cannot be readily observed; vaso-motor changes, affections of the alimentary canal, the skin and so forth. Now the essence of the James-Lange view, as applied to these congenital effects, is that though we are justified in speaking of them as effects of the stimulation, we are not justified, without further evidence, in speaking of them as effects of the emotional state. May it not rather be that the emotion as a primary mode of experience is the concomitant of the net result of the organic situation--the initial presentation, the instinctive mode of behaviour, the visceral disturbances? According to this interpretation the primary tissue of experience of the emotional order, felt as an unanalysed complex, is generated by the stimulation of the sensorium by afferent or incoming physiological impulses from the special senses, from the organs concerned in the responsive behaviour, from the viscera and vaso-motor system. Some psychologists, however, contend that the emotional experience is generated in the sensorium prior to, and not subsequent to, the behaviour-response and the visceral disturbances. It is a direct and not an indirect outcome of the presentation to the special senses. Be this as it may, there is a growing tendency to bring into the closest possible relation, or even to identify, instinct and emotion in their primary genesis. The central core of all such interpretations is that instinctive behaviour and experience, its emotional accompaniments, and its expression, are but different aspects of the outcome of the same organic occurrences. Such emotions are, therefore, only a distinguishable aspect of the primary tissue of experience and exhibit a like differentiation. Here again a biological foundation is laid for a psychological doctrine of the mental development of the individual. The intimate relation between emotion as a psychological mode of experience and expression as a group of organic conditions has an important bearing on biological interpretation. The emotion, as the psychological accompaniment of orderly disturbances in the central nervous system profoundly influences behaviour and often renders it more vigorous and more effective. The utility of the emotions in the struggle for existence can, therefore, scarcely be over-estimated. Just as keenness of perception has survival-value; just as it is obviously subject to variation; just as it must be enhanced under natural selection, whether individually acquired increments are inherited or not; and just as its value lies not only in this or that special perceptive act but in its importance for life as a whole; so the vigorous effectiveness of activity has survival-value; it is subject to variation; it must be enhanced under natural selection; and its importance lies not only in particular modes of behaviour but in its value for life as a whole. If emotion and its expression as a congenital endowment are but different aspects of the same biological occurrence; and if this is a powerful supplement to vigour effectiveness and persistency of behaviour, it must on Darwin's principles be subject to natural selection. If we include under the expression of the emotions not only the premonitory symptoms of the initial phases of the organic and mental state, not only the signs or conditions of half-tide emotion, but the full-tide manifestation of an emotion which dominates the situation, we are naturally led on to the consideration of many of the phenomena which are discussed under the head of sexual selection. The subject is difficult and complex, and it was treated by Darwin with all the strength he could summon to the task. It can only be dealt with here from a special point of view--that which may serve to illustrate the influence of certain mental factors on the course of evolution. From this point of view too much stress can scarcely be laid on the dominance of emotion during the period of courtship and pairing in the more highly organised animals. It is a period of maximum vigour, maximum activity, and, correlated with special modes of behaviour and special organic and visceral accompaniments, a period also of maximum emotional excitement. The combats of males, their dances and aerial evolutions, their elaborate behaviour and display, or the flood of song in birds, are emotional expressions which are at any rate coincident in time with sexual periodicity. From the combat of the males there follows on Darwin's principles the elimination of those which are deficient in bodily vigour, deficient in special structures, offensive or protective, which contribute to success, deficient in the emotional supplement of which persistent and whole-hearted fighting is the expression, and deficient in alertness and skill which are the outcome of the psychological development of the powers of perception. Few biologists question that we have here a mode of selection of much importance, though its influence on psychological evolution often fails to receive its due emphasis. Mr Wallace ("Darwinism", pages 282, 283, London, 1889.) regards it as "a form of natural selection"; "to it," he says, "we must impute the development of the exceptional strength, size, and activity of the male, together with the possession of special offensive and defensive weapons, and of all other characters which arise from the development of these or are correlated with them." So far there is little disagreement among the followers of Darwin--for Mr Wallace, with fine magnanimity, has always preferred to be ranked as such, notwithstanding his right, on which a smaller man would have constantly insisted, to the claim of independent originator of the doctrine of natural selection. So far with regard to sexual selection Darwin and Mr Wallace are agreed; so far and no farther. For Darwin, says Mr Wallace (Ibid. page 283.), "has extended the principle into a totally different field of action, which has none of that character of constancy and of inevitable result that attaches to natural selection, including male rivalry; for by far the larger portion of the phenomena, which he endeavours to explain by the direct action of sexual selection, can only be so explained on the hypothesis that the immediate agency is female choice or preference. It is to this that he imputes the origin of all secondary sexual characters other than weapons of offence and defence... In this extension of sexual selection to include the action of female choice or preference, and in the attempt to give to that choice such wide-reaching effects, I am unable to follow him more than a very little way." Into the details of Mr Wallace's criticisms it is impossible to enter here. We cannot discuss either the mode of origin of the variations in structure which have rendered secondary sexual characters possible or the modes of selection other than sexual which have rendered them, within narrow limits, specifically constant. Mendelism and mutation theories may have something to say on the subject when these theories have been more fully correlated with the basal principles of selection. It is noteworthy that Mr Wallace says ("Darwinism", pages 283, 284.): "Besides the acquisition of weapons by the male for the purpose of fighting with other males, there are some other sexual characters which may have been produced by natural selection. Such are the various sounds and odours which are peculiar to the male, and which serve as a call to the female or as an indication of his presence. These are evidently a valuable addition to the means of recognition of the two sexes, and are a further indication that the pairing season has arrived; and the production, intensification, and differentiation of these sounds and odours are clearly within the power of natural selection. The same remark will apply to the peculiar calls of birds, and even to the singing of the males." Why the same remark should not apply to their colours and adornments is not obvious. What is obvious is that "means of recognition" and "indication that the pairing season has arrived" are dependent on the perceptive powers of the female who recognises and for whom the indication has meaning. The hypothesis of female preference, stripped of the aesthetic surplusage which is psychologically both unnecessary and unproven, is really only different in degree from that which Mr Wallace admits in principle when he says that it is probable that the female is pleased or excited by the display. Let us for our present purpose leave on one side and regard as sub judice the question whether the specific details of secondary sexual characters are the outcome of female choice. For us the question is whether certain psychological accompaniments of the pairing situation have influenced the course of evolution and whether these psychological accompaniments are themselves the outcome of evolution. As a matter of observation, specially differentiated modes of behaviour, often very elaborate, frequently requiring highly developed skill, and apparently highly charged with emotional tone, are the precursors of pairing. They are generally confined to the males, whose fierce combats during the period of sexual activity are part of the emotional manifestation. It is inconceivable that they have no biological meaning; and it is difficult to conceive that they have any other biological end than to evoke in the generally more passive female the pairing impulse. They are based on instinctive foundations ingrained in the nervous constitution through natural (or may we not say sexual?) selection in virtue of their profound utility. They are called into play by a specialised presentation such as the sight or the scent of the female at, or a little in advance of, a critical period of the physiological rhythm. There is no necessity that the male should have any knowledge of the end to which his strenuous activity leads up. In presence of the female there is an elaborate application of all the energies of behaviour, just because ages of racial preparation have made him biologically and emotionally what he is--a functionally sexual male that must dance or sing or go through hereditary movements of display, when the appropriate stimulation comes. Of course after the first successful courtship his future behaviour will be in some degree modified by his previous experience. No doubt during his first courtship he is gaining the primary data of a peculiarly rich experience, instinctive and emotional. But the biological foundations of the behaviour of courtship are laid in the hereditary coordinations. It would seem that in some cases, not indeed in all, but perhaps especially in those cases in which secondary sexual behaviour is most highly evolved,--correlative with the ardour of the male is a certain amount of reluctance in the female. The pairing act on her part only takes place after prolonged stimulation, for affording which the behaviour of male courtship is the requisite presentation. The most vigorous, defiant and mettlesome male is preferred just because he alone affords a contributory stimulation adequate to evoke the pairing impulse with its attendant emotional tone. It is true that this places female preference or choice on a much lower psychological plane than Darwin in some passages seems to contemplate where, for example, he says that the female appreciates the display of the male and places to her credit a taste for the beautiful. But Darwin himself distinctly states ("Descent of Man" (2nd edition), Vol. II. pages 136, 137; (Popular edition), pages 642, 643.) that "it is not probable that she consciously deliberates; but she is most excited or attracted by the most beautiful, or melodious, or gallant males." The view here put forward, which has been developed by Prof. Groos ("The Play of Animals", page 244, London, 1898.), therefore seems to have Darwin's own sanction. The phenomena are not only biological; there are psychological elements as well. One can hardly suppose that the female is unconscious of the male's presence; the final yielding must surely be accompanied by heightened emotional tone. Whether we call it choice or not is merely a matter of definition of terms. The behaviour is in part determined by supplementary psychological values. Prof. Groos regards the coyness of females as "a most efficient means of preventing the too early and too frequent yielding to the sexual impulse." (Ibid. page 283.) Be that as it may, it is, in any case, if we grant the facts, a means through which male sexual behaviour with all its biological and psychological implications, is raised to a level otherwise perhaps unattainable by natural means, while in the female it affords opportunities for the development in the individual and evolution in the race of what we may follow Darwin in calling appreciation, if we empty this word of the aesthetic implications which have gathered round it in the mental life of man. Regarded from this standpoint sexual selection, broadly considered, has probably been of great importance. The psychological accompaniments of the pairing situation have profoundly influenced the course of biological evolution and are themselves the outcome of that evolution. Darwin makes only passing reference to those modes of behaviour in animals which go by the name of play. "Nothing," he says ("Descent of Man", Vol. II. page 60; (Popular edition), page 566.), "is more common than for animals to take pleasure in practising whatever instinct they follow at other times for some real good." This is one of the very numerous cases in which a hint of the master has served to stimulate research in his disciples. It was left to Prof. Groos to develop this subject on evolutionary lines and to elaborate in a masterly manner Darwin's suggestion. "The utility of play," he says ("The Play of Animals", page 76.), "is incalculable. This utility consists in the practice and exercise it affords for some of the more important duties of life,"--that is to say, for the performance of activities which will in adult life be essential to survival. He urges (Ibid. page 75.) that "the play of young animals has its origin in the fact that certain very important instincts appear at a time when the animal does not seriously need them." It is, however, questionable whether any instincts appear at a time when they are not needed. And it is questionable whether the instinctive and emotional attitude of the play-fight, to take one example, can be identified with those which accompany fighting in earnest, though no doubt they are closely related and have some common factors. It is probable that play, as preparatory behaviour, differs in biological detail (as it almost certainly does in emotional attributes) from the earnest of after-life and that it has been evolved through differentiation and integration of the primary tissue of experience, as a preparation through which certain essential modes of skill may be acquired--those animals in which the preparatory play-propensity was not inherited in due force and requisite amount being subsequently eliminated in the struggle for existence. In any case there is little question that Prof. Groos is right in basing the play-propensity on instinctive foundations. ("The Play of Animals" page 24.) None the less, as he contends, the essential biological value of play is that it is a means of training the educable nerve-tissue, of developing that part of the brain which is modified by experience and which thus acquires new characters, of elaborating the secondary tissue of experience on the predetermined lines of instinctive differentiation and thus furthering the psychological activities which are included under the comprehensive term "intelligent." In "The Descent of Man" Darwin dealt at some length with intelligence and the higher mental faculties. ("Descent of Man" (1st edition), Chapters II, III, V; (2nd edition), Chapters III, IV, V.) His object, he says, is to show that there is no fundamental difference between man and the higher mammals in their mental faculties; that these faculties are variable and the variations tend to be inherited; and that under natural selection beneficial variations of all kinds will have been preserved and injurious ones eliminated. Darwin was too good an observer and too honest a man to minimise the "enormous difference" between the level of mental attainment of civilised man and that reached by any animal. His contention was that the difference, great as it is, is one of degree and not of kind. He realised that, in the development of the mental faculties of man, new factors in evolution have supervened--factors which play but a subordinate and subsidiary part in animal intelligence. Intercommunication by means of language, approbation and blame, and all that arises out of reflective thought, are but foreshadowed in the mental life of animals. Still he contends that these may be explained on the doctrine of evolution. He urges (Ibid. Vol. I. pages 70, 71; (Popular edition), pages 70, 71.)" that man is variable in body and mind; and that the variations are induced, either directly or indirectly, by the same general causes, and obey the same general laws, as with the lower animals." He correlates mental development with the evolution of the brain. (Ibid. page 81.) "As the various mental faculties gradually developed themselves, the brain would almost certainly become larger. No one, I presume, doubts that the large proportion which the size of man's brain bears to his body, compared to the same proportion in the gorilla or orang, is closely connected with his higher mental powers." "With respect to the lower animals," he says ("Descent of Man" (Popular edition), page 82.), "M.E. Lartet ("Comptes Rendus des Sciences", June 1, 1868.), by comparing the crania of tertiary and recent mammals belonging to the same groups, has come to the remarkable conclusion that the brain is generally larger and the convolutions are more complex in the more recent form." Sir E. Ray Lankester has sought to express in the simplest terms the implications of the increase in size of the cerebrum. "In what," he asks, "does the advantage of a larger cerebral mass consist?" "Man," he replies "is born with fewer ready-made tricks of the nerve-centres--these performances of an inherited nervous mechanism so often called by the ill-defined term 'instincts'--than are the monkeys or any other animal. Correlated with the absence of inherited ready-made mechanism, man has a greater capacity of developing in the course of his individual growth similar nervous mechanisms (similar to but not identical with those of 'instinct') than any other animal... The power of being educated--'educability' as we may term it--is what man possesses in excess as compared with the apes. I think we are justified in forming the hypothesis that it is this 'educability' which is the correlative of the increased size of the cerebrum." There has been natural selection of the more educable animals, for "the character which we describe as 'educability' can be transmitted, it is a congenital character. But the RESULTS of education can NOT be transmitted. In each generation they have to be acquired afresh, and with increased 'educability' they are more readily acquired and a larger variety of them... The fact is that there is no community between the mechanisms of instinct and the mechanisms of intelligence, and that the latter are later in the history of the evolution of the brain than the former and can only develop in proportion as the former become feeble and defective." ("Nature", Vol. LXI. pages 624, 625 (1900).) In this statement we have a good example of the further development of views which Darwin foreshadowed but did not thoroughly work out. It states the biological case clearly and tersely. Plasticity of behaviour in special accommodation to special circumstances is of survival value; it depends upon acquired characters; it is correlated with increase in size and complexity of the cerebrum; under natural selection therefore the larger and more complex cerebrum as the organ of plastic behaviour has been the outcome of natural selection. We have thus the biological foundations for a further development of genetic psychology. There are diversities of opinion, as Darwin showed, with regard to the range of instinct in man and the higher animals as contrasted with lower types. Darwin himself said ("Descent of Man", Vol. I. page 100.) that "Man, perhaps, has somewhat fewer instincts than those possessed by the animals which come next to him in the series." On the other hand, Prof. Wm. James says ("Principles of Psychology," Vol. II. page 289.) that man is probably the animal with most instincts. The true position is that man and the higher animals have fewer complete and self-sufficing instincts than those which stand lower in the scale of mental evolution, but that they have an equally large or perhaps larger mass of instinctive raw material which may furnish the stuff to be elaborated by intelligent processes. There is, perhaps, a greater abundance of the primary tissue of experience to be refashioned and integrated by secondary modification; there is probably the same differentiation in relation to the determining biological ends, but there is at the outset less differentiation of the particular and specific modes of behaviour. The specialised instinctive performances and their concomitant experience-complexes are at the outset more indefinite. Only through acquired connections, correlated with experience, do they become definitely organised. The full working-out of the delicate and subtle relationship of instinct and educability--that is, of the hereditary and the acquired factors in the mental life--is the task which lies before genetic and comparative psychology. They interact throughout the whole of life, and their interactions are very complex. No one can read the chapters of "The Descent of Man" which Darwin devotes to a consideration of the mental characters of man and animals without noticing, on the one hand, how sedulous he is in his search for hereditary foundations, and, on the other hand, how fully he realises the importance of acquired habits of mind. The fact that educability itself has innate tendencies--is in fact a partially differentiated educability--renders the unravelling of the factors of mental progress all the more difficult. In his comparison of the mental powers of men and animals it was essential that Darwin should lay stress on points of similarity rather than on points of difference. Seeking to establish a doctrine of evolution, with its basal concept of continuity of process and community of character, he was bound to render clear and to emphasise the contention that the difference in mind between man and the higher animals, great as it is, is one of degree and not of kind. To this end Darwin not only recorded a large number of valuable observations of his own, and collected a considerable body of information from reliable sources, he presented the whole subject in a new light and showed that a natural history of mind might be written and that this method of study offered a wide and rich field for investigation. Of course those who regarded the study of mind only as a branch of metaphysics smiled at the philosophical ineptitude of the mere man of science. But the investigation, on natural history lines, has been prosecuted with a large measure of success. Much indeed still remains to be done; for special training is required, and the workers are still few. Promise for the future is however afforded by the fact that investigation is prosecuted on experimental lines and that something like organised methods of research are taking form. There is now but little reliance on casual observations recorded by those who have not undergone the necessary discipline in these methods. There is also some change of emphasis in formulating conclusions. Now that the general evolutionary thesis is fully and freely accepted by those who carry on such researches, more stress is laid on the differentiation of the stages of evolutionary advance than on the fact of their underlying community of nature. The conceptual intelligence which is especially characteristic of the higher mental procedure of man is more firmly distinguished from the perceptual intelligence which he shares with the lower animals--distinguished now as a higher product of evolution, no longer as differing in origin or different in kind. Some progress has been made, on the one hand in rendering an account of intelligent profiting by experience under the guidance of pleasure and pain in the perceptual field, on lines predetermined by instinctive differentiation for biological ends, and on the other hand in elucidating the method of conceptual thought employed, for example, by the investigator himself in interpreting the perceptual experience of the lower animals. Thus there is a growing tendency to realise more fully that there are two orders of educability--first an educability of the perceptual intelligence based on the biological foundation of instinct, and secondly an educability of the conceptual intelligence which refashions and rearranges the data afforded by previous inheritance and acquisition. It is in relation to this second and higher order of educability that the cerebrum of man shows so large an increase of mass and a yet larger increase of effective surface through its rich convolutions. It is through educability of this order that the human child is brought intellectually and affectively into touch with the ideal constructions by means of which man has endeavoured, with more or less success, to reach an interpretation of nature, and to guide the course of the further evolution of his race--ideal constructions which form part of man's environment. It formed no part of Darwin's purpose to consider, save in broad outline, the methods, or to discuss in any fulness of detail the results of the process by which a differentiation of the mental faculties of man from those of the lower animals has been brought about--a differentiation the existence of which he again and again acknowledges. His purpose was rather to show that, notwithstanding this differentiation, there is basal community in kind. This must be remembered in considering his treatment of the biological foundations on which man's systems of ethics are built. He definitely stated that he approached the subject "exclusively from the side of natural history." ("Descent of Man", Vol. I. page 149.) His general conclusion is that the moral sense is fundamentally identical with the social instincts, which have been developed for the good of the community; and he suggests that the concept which thus enables us to interpret the biological ground-plan of morals also enables us to frame a rational ideal of the moral end. "As the social instincts," he says (Ibid. page 185.), "both of man and the lower animals have no doubt been developed by nearly the same steps, it would be advisable, if found practicable, to use the same definition in both cases, and to take as the standard of morality, the general good or welfare of the community, rather than the general happiness." But the kind of community for the good of which the social instincts of animals and primitive men were biologically developed may be different from that which is the product of civilisation, as Darwin no doubt realised. Darwin's contention was that conscience is a social instinct and has been evolved because it is useful to the tribe in the struggle for existence against other tribes. On the other hand, J.S. Mill urged that the moral feelings are not innate but acquired, and Bain held the same view, believing that the moral sense is acquired by each individual during his life-time. Darwin, who notes (Ibid. page 150 (footnote).) their opinion with his usual candour, adds that "on the general theory of evolution this is at least extremely improbable. It is impossible to enter into the question here: much turns on the exact connotation of the terms "conscience" and "moral sense," and on the meaning we attach to the statement that the moral sense is fundamentally identical with the social instincts." Presumably the majority of those who approach the subjects discussed in the third, fourth and fifth chapters of "The Descent of Man" in the full conviction that mental phenomena, not less than organic phenomena, have a natural genesis, would, without hesitation, admit that the intellectual and moral systems of civilised man are ideal constructions, the products of conceptual thought, and that as such they are, in their developed form, acquired. The moral sentiments are the emotional analogues of highly developed concepts. This does not however imply that they are outside the range of natural history treatment. Even though it may be desirable to differentiate the moral conduct of men from the social behaviour of animals (to which some such term as "pre-moral" or "quasi-moral" may be applied), still the fact remains that, as Darwin showed, there is abundant evidence of the occurrence of such social behaviour--social behaviour which, even granted that it is in large part intelligently acquired, and is itself so far a product of educability, is of survival value. It makes for that integration without which no social group could hold together and escape elimination. Furthermore, even if we grant that such behaviour is intelligently acquired, that is to say arises through the modification of hereditary instincts and emotions, the fact remains that only through these instinctive and emotional data is afforded the primary tissue of the experience which is susceptible of such modification. Darwin sought to show, and succeeded in showing, that for the intellectual and moral life there are instinctive foundations which a biological treatment alone can disclose. It is true that he did not in all cases analytically distinguish the foundations from the superstructure. Even to-day we are scarcely in a position to do so adequately. But his treatment was of great value in giving an impetus to further research. This value indeed can scarcely be overestimated. And when the natural history of the mental operations shall have been written, the cardinal fact will stand forth, that the instinctive and emotional foundations are the outcome of biological evolution and have been ingrained in the race through natural selection. We shall more clearly realise that educability itself is a product of natural selection, though the specific results acquired through cerebral modifications are not transmitted through heredity. It will, perhaps, also be realised that the instinctive foundations of social behaviour are, for us, somewhat out of date and have undergone but little change throughout the progress of civilisation, because natural selection has long since ceased to be the dominant factor in human progress. The history of human progress has been mainly the history of man's higher educability, the products of which he has projected on to his environment. This educability remains on the average what it was a dozen generations ago; but the thought-woven tapestry of his surroundings is refashioned and improved by each succeeding generation. Few men have in greater measure enriched the thought-environment with which it is the aim of education to bring educable human beings into vital contact, than has Charles Darwin. His special field of work was the wide province of biology; but he did much to help us realise that mental factors have contributed to organic evolution and that in man, the highest product of Evolution, they have reached a position of unquestioned supremacy. XXII. THE INFLUENCE OF THE CONCEPTION OF EVOLUTION ON MODERN PHILOSOPHY. By H. Hoffding. Professor of Philosophy in the University of Copenhagen. I. It is difficult to draw a sharp line between philosophy and natural science. The naturalist who introduces a new principle, or demonstrates a fact which throws a new light on existence, not only renders an important service to philosophy but is himself a philosopher in the broader sense of the word. The aim of philosophy in the stricter sense is to attain points of view from which the fundamental phenomena and the principles of the special sciences can be seen in their relative importance and connection. But philosophy in this stricter sense has always been influenced by philosophy in the broader sense. Greek philosophy came under the influence of logic and mathematics, modern philosophy under the influence of natural science. The name of Charles Darwin stands with those of Galileo, Newton, and Robert Mayer--names which denote new problems and great alterations in our conception of the universe. First of all we must lay stress on Darwin's own personality. His deep love of truth, his indefatigable inquiry, his wide horizon, and his steady self-criticism make him a scientific model, even if his results and theories should eventually come to possess mainly an historical interest. In the intellectual domain the primary object is to reach high summits from which wide surveys are possible, to reach them toiling honestly upwards by way of experience, and then not to turn dizzy when a summit is gained. Darwinians have sometimes turned dizzy, but Darwin never. He saw from the first the great importance of his hypothesis, not only because of its solution of the old problem as to the value of the concept of species, not only because of the grand picture of natural evolution which it unrolls, but also because of the life and inspiration its method would impart to the study of comparative anatomy, of instinct and of heredity, and finally because of the influence it would exert on the whole conception of existence. He wrote in his note-book in the year 1837: "My theory would give zest to recent and fossil comparative anatomy; it would lead to the study of instinct, heredity, and mind-heredity, whole (of) metaphysics." ("Life and Letters of Charles Darwin", Vol. I. page 8.) We can distinguish four main points in which Darwin's investigations possess philosophical importance. The evolution hypothesis is much older than Darwin; it is, indeed, one of the oldest guessings of human thought. In the eighteenth century it was put forward by Diderot and Lamettrie and suggested by Kant (1786). As we shall see later, it was held also by several philosophers in the first half of the nineteenth century. In his preface to "The Origin of Species", Darwin mentions the naturalists who were his forerunners. But he has set forth the hypothesis of evolution in so energetic and thorough a manner that it perforce attracts the attention of all thoughtful men in a much higher degree than it did before the publication of the "Origin". And further, the importance of his teaching rests on the fact that he, much more than his predecessors, even than Lamarck, sought a foundation for his hypothesis in definite facts. Modern science began by demanding--with Kepler and Newton--evidence of verae causae; this demand Darwin industriously set himself to satisfy--hence the wealth of material which he collected by his observations and his experiments. He not only revived an old hypothesis, but he saw the necessity of verifying it by facts. Whether the special cause on which he founded the explanation of the origin of species--Natural Selection--is sufficient, is now a subject of discussion. He himself had some doubt in regard to this question, and the criticisms which are directed against his hypothesis hit Darwinism rather than Darwin. In his indefatigable search for empirical evidence he is a model even for his antagonists: he has compelled them to approach the problems of life along other lines than those which were formerly followed. Whether the special cause to which Darwin appealed is sufficient or not, at least to it is probably due the greater part of the influence which he has exerted on the general trend of thought. "Struggle for existence" and "natural selection" are principles which have been applied, more or less, in every department of thought. Recent research, it is true, has discovered greater empirical discontinuity--leaps, "mutations"--whereas Darwin believed in the importance of small variations slowly accumulated. It has also been shown by the experimental method, which in recent biological work has succeeded Darwin's more historical method, that types once constituted possess great permanence, the fluctuations being restricted within clearly defined boundaries. The problem has become more precise, both as to variation and as to heredity. The inner conditions of life have in both respects shown a greater independence than Darwin had supposed in his theory, though he always admitted that the cause of variation was to him a great enigma, "a most perplexing problem," and that the struggle for life could only occur where variation existed. But, at any rate, it was of the greatest importance that Darwin gave a living impression of the struggle for life which is everywhere going on, and to which even the highest forms of existence must be amenable. The philosophical importance of these ideas does not stand or fall with the answer to the question, whether natural selection is a sufficient explanation of the origin of species or not: it has an independent, positive value for everyone who will observe life and reality with an unbiassed mind. In accentuating the struggle for life Darwin stands as a characteristically English thinker: he continues a train of ideas which Hobbes and Malthus had already begun. Moreover in his critical views as to the conception of species he had English forerunners; in the middle ages Occam and Duns Scotus, in the eighteenth century Berkeley and Hume. In his moral philosophy, as we shall see later, he is an adherent of the school which is represented by Hutcheson, Hume and Adam Smith. Because he is no philosopher in the stricter sense of the term, it is of great interest to see that his attitude of mind is that of the great thinkers of his nation. In considering Darwin's influence on philosophy we will begin with an examination of the attitude of philosophy to the conception of evolution at the time when "The Origin of Species" appeared. We will then examine the effects which the theory of evolution, and especially the idea of the struggle for life, has had, and naturally must have, on the discussion of philosophical problems. II. When "The Origin of Species" appeared fifty years ago Romantic speculation, Schelling's and Hegel's philosophy, still reigned on the continent, while in England Positivism, the philosophy of Comte and Stuart Mill, represented the most important trend of thought. German speculation had much to say on evolution, it even pretended to be a philosophy of evolution. But then the word "evolution" was to be taken in an ideal, not in a real, sense. To speculative thought the forms and types of nature formed a system of ideas, within which any form could lead us by continuous transitions to any other. It was a classificatory system which was regarded as a divine world of thought or images, within which metamorphoses could go on--a condition comparable with that in the mind of the poet when one image follows another with imperceptible changes. Goethe's ideas of evolution, as expressed in his "Metamorphosen der Pflanzen und der Thiere", belong to this category; it is, therefore, incorrect to call him a forerunner of Darwin. Schelling and Hegel held the same idea; Hegel expressly rejected the conception of a real evolution in time as coarse and materialistic. "Nature," he says, "is to be considered as a SYSTEM OF STAGES, the one necessarily arising from the other, and being the nearest truth of that from which it proceeds; but not in such a way that the one is NATURALLY generated by the other; on the contrary (their connection lies) in the inner idea which is the ground of nature. The METAMORPHOSIS can be ascribed only to the notion as such, because it alone is evolution... It has been a clumsy idea in the older as well as in the newer philosophy of nature, to regard the transformation and the transition from one natural form and sphere to a higher as an outward and actual production." ("Encyclopaedie der philosophischen Wissenschaften" (4th edition), Berlin, 1845, paragraph 249.) The only one of the philosophers of Romanticism who believed in a real, historical evolution, a real production of new species, was Oken. ("Lehrbuch der Naturphilosophie", Jena, 1809.) Danish philosophers, such as Treschow (1812) and Sibbern (1846), have also broached the idea of an historical evolution of all living beings from the lowest to the highest. Schopenhauer's philosophy has a more realistic character than that of Schelling's and Hegel's, his diametrical opposites, though he also belongs to the romantic school of thought. His philosophical and psychological views were greatly influenced by French naturalists and philosophers, especially by Cabanis and Lamarck. He praises the "ever memorable Lamarck," because he laid so much stress on the "will to live." But he repudiates as a "wonderful error" the idea that the organs of animals should have reached their present perfection through a development in time, during the course of innumerable generations. It was, he said, a consequence of the low standard of contemporary French philosophy, that Lamarck came to the idea of the construction of living beings in time through succession! ("Ueber den Willen in der Natur" (2nd edition), Frankfurt a. M., 1854, pages 41-43.) The positivistic stream of thought was not more in favour of a real evolution than was the Romantic school. Its aim was to adhere to positive facts: it looked with suspicion on far-reaching speculation. Comte laid great stress on the discontinuity found between the different kingdoms of nature, as well as within each single kingdom. As he regarded as unscientific every attempt to reduce the number of physical forces, so he rejected entirely the hypothesis of Lamarck concerning the evolution of species; the idea of species would in his eyes absolutely lose its importance if a transition from species to species under the influence of conditions of life were admitted. His disciples (Littre, Robin) continued to direct against Darwin the polemics which their master had employed against Lamarck. Stuart Mill, who, in the theory of knowledge, represented the empirical or positivistic movement in philosophy--like his English forerunners from Locke to Hume--founded his theory of knowledge and morals on the experience of the single individual. He sympathised with the theory of the original likeness of all individuals and derived their differences, on which he practically and theoretically laid much stress, from the influence both of experience and education, and, generally, of physical and social causes. He admitted an individual evolution, and, in the human species, an evolution based on social progress; but no physiological evolution of species. He was afraid that the hypothesis of heredity would carry us back to the old theory of "innate" ideas. Darwin was more empirical than Comte and Mill; experience disclosed to him a deeper continuity than they could find; closer than before the nature and fate of the single individual were shown to be interwoven in the great web binding the life of the species with nature as a whole. And the continuity which so many idealistic philosophers could find only in the world of thought, he showed to be present in the world of reality. III. Darwin's energetic renewal of the old idea of evolution had its chief importance in strengthening the conviction of this real continuity in the world, of continuity in the series of form and events. It was a great support for all those who were prepared to base their conception of life on scientific grounds. Together with the recently discovered law of the conservation of energy, it helped to produce the great realistic movement which characterises the last third of the nineteenth century. After the decline of the Romantic movement people wished to have firmer ground under their feet and reality now asserted itself in a more emphatic manner than in the period of Romanticism. It was easy for Hegel to proclaim that "the real" was "the rational," and that "the rational" was "the real": reality itself existed for him only in the interpretation of ideal reason, and if there was anything which could not be merged in the higher unity of thought, then it was only an example of the "impotence of nature to hold to the idea." But now concepts are to be founded on nature and not on any system of categories too confidently deduced a priori. The new devotion to nature had its recompense in itself, because the new points of view made us see that nature could indeed "hold to ideas," though perhaps not to those which we had cogitated beforehand. A most important question for philosophers to answer was whether the new views were compatible with an idealistic conception of life and existence. Some proclaimed that we have now no need of any philosophy beyond the principles of the conservation of matter and energy and the principle of natural evolution: existence should and could be definitely and completely explained by the laws of material nature. But abler thinkers saw that the thing was not so simple. They were prepared to give the new views their just place and to examine what alterations the old views must undergo in order to be brought into harmony with the new data. The realistic character of Darwin's theory was shown not only in the idea of natural continuity, but also, and not least, in the idea of the cause whereby organic life advances step by step. This idea--the idea of the struggle for life--implied that nothing could persist, if it had no power to maintain itself under the given conditions. Inner value alone does not decide. Idealism was here put to its hardest trial. In continuous evolution it could perhaps still find an analogy to the inner evolution of ideas in the mind; but in the demand for power in order to struggle with outward conditions Realism seemed to announce itself in its most brutal form. Every form of Idealism had to ask itself seriously how it was going to "struggle for life" with this new Realism. We will now give a short account of the position which leading thinkers in different countries have taken up in regard to this question. I. Herbert Spencer was the philosopher whose mind was best prepared by his own previous thinking to admit the theory of Darwin to a place in his conception of the world. His criticism of the arguments which had been put forward against the hypothesis of Lamarck, showed that Spencer, as a young man, was an adherent to the evolution idea. In his "Social Statics" (1850) he applied this idea to human life and moral civilisation. In 1852 he wrote an essay on "The Development Hypothesis", in which he definitely stated his belief that the differentiation of species, like the differentiation within a single organism, was the result of development. In the first edition of his "Psychology" (1855) he took a step which put him in opposition to the older English school (from Locke to Mill): he acknowledged "innate ideas" so far as to admit the tendency of acquired habits to be inherited in the course of generations, so that the nature and functions of the individual are only to be understood through its connection with the life of the species. In 1857, in his essay on "Progress", he propounded the law of differentiation as a general law of evolution, verified by examples from all regions of experience, the evolution of species being only one of these examples. On the effect which the appearance of "The Origin of Species" had on his mind he writes in his "Autobiography": "Up to that time... I held that the sole cause of organic evolution is the inheritance of functionally-produced modifications. The "Origin of Species" made it clear to me that I was wrong, and that the larger part of the facts cannot be due to any such cause... To have the theory of organic evolution justified was of course to get further support for that theory of evolution at large with which... all my conceptions were bound up." (Spencer, "Autobiography", Vol. II. page 50, London, 1904.) Instead of the metaphorical expression "natural selection," Spencer introduced the term "survival of the fittest," which found favour with Darwin as well as with Wallace. In working out his ideas of evolution, Spencer found that differentiation was not the only form of evolution. In its simplest form evolution is mainly a concentration, previously scattered elements being integrated and losing independent movement. Differentiation is only forthcoming when minor wholes arise within a greater whole. And the highest form of evolution is reached when there is a harmony between concentration and differentiation, a harmony which Spencer calls equilibration and which he defines as a moving equilibrium. At the same time this definition enables him to illustrate the expression "survival of the fittest." "Every living organism exhibits such a moving equilibrium--a balanced set of functions constituting its life; and the overthrow of this balanced set of functions or moving equilibrium is what we call death. Some individuals in a species are so constituted that their moving equilibria are less easily overthrown than those of other individuals; and these are the fittest which survive, or, in Mr Darwin's language, they are the select which nature preserves." (Ibid. page 100.) Not only in the domain of organic life, but in all domains, the summit of evolution is, according to Spencer, characterised by such a harmony--by a moving equilibrium. Spencer's analysis of the concept of evolution, based on a great variety of examples, has made this concept clearer and more definite than before. It contains the three elements; integration, differentiation and equilibration. It is true that a concept which is to be valid for all domains of experience must have an abstract character, and between the several domains there is, strictly speaking, only a relation of analogy. So there is only analogy between psychical and physical evolution. But this is no serious objection, because general concepts do not express more than analogies between the phenomena which they represent. Spencer takes his leading terms from the material world in defining evolution (in the simplest form) as integration of matter and dissipation of movement; but as he--not always quite consistently (Cf. my letter to him, 1876, now printed in Duncan's "Life and Letters of Herbert Spencer", page 178, London, 1908.)--assumed a correspondence of mind and matter, he could very well give these terms an indirect importance for psychical evolution. Spencer has always, in my opinion with full right, repudiated the ascription of materialism. He is no more a materialist than Spinoza. In his "Principles of Psychology" (paragraph 63) he expressed himself very clearly: "Though it seems easier to translate so-called matter into so-called spirit, than to translate so-called spirit into so-called matter--which latter is indeed wholly impossible--yet no translation can carry us beyond our symbols." These words lead us naturally to a group of thinkers whose starting-point was psychical evolution. But we have still one aspect of Spencer's philosophy to mention. Spencer founded his "laws of evolution" on an inductive basis, but he was convinced that they could be deduced from the law of the conservation of energy. Such a deduction is, perhaps, possible for the more elementary forms of evolution, integration and differentiation; but it is not possible for the highest form, the equilibration, which is a harmony of integration and differentiation. Spencer can no more deduce the necessity for the eventual appearance of "moving equilibria" of harmonious totalities than Hegel could guarantee the "higher unities" in which all contradictions should be reconciled. In Spencer's hands the theory of evolution acquired a more decidedly optimistic character than in Darwin's; but I shall deal later with the relation of Darwin's hypothesis to the opposition of optimism and pessimism. II. While the starting-point of Spencer was biological or cosmological, psychical evolution being conceived as in analogy with physical, a group of eminent thinkers--in Germany Wundt, in France Fouillee, in Italy Ardigo--took, each in his own manner, their starting-point in psychical evolution as an original fact and as a type of all evolution, the hypothesis of Darwin coming in as a corroboration and as a special example. They maintain the continuity of evolution; they find this character most prominent in psychical evolution, and this is for them a motive to demand a corresponding continuity in the material, especially in the organic domain. To Wundt and Fouillee the concept of will is prominent. They see the type of all evolution in the transformation of the life of will from blind impulse to conscious choice; the theories of Lamarck and Darwin are used to support the view that there is in nature a tendency to evolution in steady reciprocity with external conditions. The struggle for life is here only a secondary fact. Its apparent prominence is explained by the circumstance that the influence of external conditions is easily made out, while inner conditions can be verified only through their effects. For Ardigo the evolution of thought was the starting-point and the type: in the evolution of a scientific hypothesis we see a progress from the indefinite (indistinto) to the definite (distinto), and this is a characteristic of all evolution, as Ardigo has pointed out in a series of works. The opposition between indistinto and distinto corresponds to Spencer's opposition between homogeneity and heterogeneity. The hypothesis of the origin of differences of species from more simple forms is a special example of the general law of evolution. In the views of Wundt and Fouillee we find the fundamental idea of idealism: psychical phenomena as expressions of the innermost nature of existence. They differ from the older Idealism in the great stress which they lay on evolution as a real, historical process which is going on through steady conflict with external conditions. The Romantic dread of reality is broken. It is beyond doubt that Darwin's emphasis on the struggle for life as a necessary condition of evolution has been a very important factor in carrying philosophy back to reality from the heaven of pure ideas. The philosophy of Ardigo, on the other side, appears more as a continuation and deepening of positivism, though the Italian thinker arrived at his point of view independently of French-English positivism. The idea of continuous evolution is here maintained in opposition to Comte's and Mill's philosophy of discontinuity. From Wundt and Fouillee Ardigo differs in conceiving psychical evolution not as an immediate revelation of the innermost nature of existence, but only as a single, though the most accessible example, of evolution. III. To the French philosophers Boutroux and Bergson, evolution proper is continuous and qualitative, while outer experience and physical science give us fragments only, sporadic processes and mechanical combinations. To Bergson, in his recent work "L'Evolution Creatrice", evolution consists in an elan de vie which to our fragmentary observation and analytic reflexion appears as broken into a manifold of elements and processes. The concept of matter in its scientific form is the result of this breaking asunder, essential for all scientific reflexion. In these conceptions the strongest opposition between inner and outer conditions of evolution is expressed: in the domain of internal conditions spontaneous development of qualitative forms--in the domain of external conditions discontinuity and mechanical combination. We see, then, that the theory of evolution has influenced philosophy in a variety of forms. It has made idealistic thinkers revise their relation to the real world; it has led positivistic thinkers to find a closer connection between the facts on which they based their views; it has made us all open our eyes for new possibilities to arise through the prima facie inexplicable "spontaneous" variations which are the condition of all evolution. This last point is one of peculiar interest. Deeper than speculative philosophy and mechanical science saw in the days of their triumph, we catch sight of new streams, whose sources and laws we have still to discover. Most sharply does this appear in the theory of mutation, which is only a stronger accentuation of a main point in Darwinism. It is interesting to see that an analogous problem comes into the foreground in physics through the discovery of radioactive phenomena, and in psychology through the assumption of psychical new formations (as held by Boutroux, William James and Bergson). From this side, Darwin's ideas, as well as the analogous ideas in other domains, incite us to renewed examination of our first principles, their rationality and their value. On the other hand, his theory of the struggle for existence challenges us to examine the conditions and discuss the outlook as to the persistence of human life and society and of the values that belong to them. It is not enough to hope (or fear?) the rising of new forms; we have also to investigate the possibility of upholding the forms and ideals which have hitherto been the bases of human life. Darwin has here given his age the most earnest and most impressive lesson. This side of Darwin's theory is of peculiar interest to some special philosophical problems to which I now pass. IV. Among philosophical problems the problem of knowledge has in the last century occupied a foremost place. It is natural, then, to ask how Darwin and the hypothesis whose most eminent representative he is, stand to this problem. Darwin started an hypothesis. But every hypothesis is won by inference from certain presuppositions, and every inference is based on the general principles of human thought. The evolution hypothesis presupposes, then, human thought and its principles. And not only the abstract logical principles are thus presupposed. The evolution hypothesis purports to be not only a formal arrangement of phenomena, but to express also the law of a real process. It supposes, then, that the real data--all that in our knowledge which we do not produce ourselves, but which we in the main simply receive--are subjected to laws which are at least analogous to the logical relations of our thoughts; in other words, it assumes the validity of the principle of causality. If organic species could arise without cause there would be no use in framing hypotheses. Only if we assume the principle of causality, is there a problem to solve. Though Darwinism has had a great influence on philosophy considered as a striving after a scientific view of the world, yet here is a point of view--the epistemological--where philosophy is not only independent but reaches beyond any result of natural science. Perhaps it will be said: the powers and functions of organic beings only persist (perhaps also only arise) when they correspond sufficiently to the conditions under which the struggle of life is to go on. Human thought itself is, then, a variation (or a mutation) which has been able to persist and to survive. Is not, then, the problem of knowledge solved by the evolution hypothesis? Spencer had given an affirmative answer to this question before the appearance of "The Origin of Species". For the individual, he said, there is an a priori, original, basis (or Anlage) for all mental life; but in the species all powers have developed in reciprocity with external conditions. Knowledge is here considered from the practical point of view, as a weapon in the struggle for life, as an "organon" which has been continuously in use for generations. In recent years the economic or pragmatic epistemology, as developed by Avenarius and Mach in Germany, and by James in America, points in the same direction. Science, it is said, only maintains those principles and presuppositions which are necessary to the simplest and clearest orientation in the world of experience. All assumptions which cannot be applied to experience and to practical work, will successively be eliminated. In these views a striking and important application is made of the idea of struggle for life to the development of human thought. Thought must, as all other things in the world, struggle for life. But this whole consideration belongs to psychology, not to the theory of knowledge (epistemology), which is concerned only with the validity of knowledge, not with its historical origin. Every hypothesis to explain the origin of knowledge must submit to cross-examination by the theory of knowledge, because it works with the fundamental forms and principles of human thought. We cannot go further back than these forms and principles, which it is the aim of epistemology to ascertain and for which no further reason can be given. (The present writer, many years ago, in his "Psychology" (Copenhagen, 1882; English translation London, 1891), criticised the evolutionistic treatment of the problem of knowledge from the Kantian point of view.) But there is another side of the problem which is, perhaps, of more importance and which epistemology generally overlooks. If new variations can arise, not only in organic but perhaps also in inorganic nature, new tasks are placed before the human mind. The question is, then, if it has forms in which there is room for the new matter? We are here touching a possibility which the great master of epistemology did not bring to light. Kant supposed confidently that no other matter of knowledge could stream forth from the dark source which he called "the thing-in-itself," than such as could be synthesised in our existing forms of knowledge. He mentions the possibility of other forms than the human, and warns us against the dogmatic assumption that the human conception of existence should be absolutely adequate. But he seems to be quite sure that the thing-in-itself works constantly, and consequently always gives us only what our powers can master. This assumption was a consequence of Kant's rationalistic tendency, but one for which no warrant can be given. Evolutionism and systematism are opposing tendencies which can never be absolutely harmonised one with the other. Evolution may at any time break some form which the system-monger regards as finally established. Darwin himself felt a great difference in looking at variation as an evolutionist and as a systematist. When he was working at his evolution theory, he was very glad to find variations; but they were a hindrance to him when he worked as a systematist, in preparing his work on Cirripedia. He says in a letter: "I had thought the same parts of the same species more resemble (than they do anyhow in Cirripedia) objects cast in the same mould. Systematic work would be easy were it not for this confounded variation, which, however, is pleasant to me as a speculatist, though odious to me as a systematist." ("Life and Letters", Vol. II. page 37.) He could indeed be angry with variations even as an evolutionist; but then only because he could not explain them, not because he could not classify them. "If, as I must think, external conditions produce little DIRECT effect, what the devil determines each particular variation?" (Ibid. page 232.) What Darwin experienced in his particular domain holds good of all knowledge. All knowledge is systematic, in so far as it strives to put phenomena in quite definite relations, one to another. But the systematisation can never be complete. And here Darwin has contributed much to widen the world for us. He has shown us forces and tendencies in nature which make absolute systems impossible, at the same time that they give us new objects and problems. There is still a place for what Lessing called "the unceasing striving after truth," while "absolute truth" (in the sense of a closed system) is unattainable so long as life and experience are going on. There is here a special remark to be made. As we have seen above, recent research has shown that natural selection or struggle for life is no explanation of variations. Hugo de Vries distinguishes between partial and embryonal variations, or between variations and mutations, only the last-named being heritable, and therefore of importance for the origin of new species. But the existence of variations is not only of interest for the problem of the origin of species; it has also a more general interest. An individual does not lose its importance for knowledge, because its qualities are not heritable. On the contrary, in higher beings at least, individual peculiarities will become more and more independent objects of interest. Knowledge takes account of the biographies not only of species, but also of individuals: it seeks to find the law of development of the single individual. (The new science of Ecology occupies an intermediate position between the biography of species and the biography of individuals. Compare "Congress of Arts and Science", St Louis, Vol. V. 1906 (the Reports of Drude and Robinson) and the work of my colleague E. Warming.) As Leibniz said long ago, individuality consists in the law of the changes of a being. "La loi du changement fait l'individualite de chaque substance." Here is a world which is almost new for science, which till now has mainly occupied itself with general laws and forms. But these are ultimately only means to understand the individual phenomena, in whose nature and history a manifold of laws and forms always cooperate. The importance of this remark will appear in the sequel. V. To many people the Darwinian theory of natural selection or struggle for existence seemed to change the whole conception of life, and particularly all the conditions on which the validity of ethical ideas depends. If only that has persistence which can be adapted to a given condition, what will then be the fate of our ideals, of our standards of good and evil? Blind force seems to reign, and the only thing that counts seems to be the most heedless use of power. Darwinism, it was said, has proclaimed brutality. No other difference seems permanent save that between the sound, powerful and happy on the one side, the sick, feeble and unhappy on the other; and every attempt to alleviate this difference seems to lead to general enervation. Some of those who interpreted Darwinism in this manner felt an aesthetic delight in contemplating the heedlessness and energy of the great struggle for existence and anticipated the realisation of a higher human type as the outcome of it: so Nietzsche and his followers. Others recognising the same consequences in Darwinism regarded these as one of the strongest objections against it; so Duhring and Kropotkin (in his earlier works). This interpretation of Darwinism was frequent in the interval between the two main works of Darwin--"The Origin of Species" and "The Descent of Man". But even during this interval it was evident to an attentive reader that Darwin himself did not found his standard of good and evil on the features of the life of nature he had emphasised so strongly. He did not justify the ways along which nature reached its ends; he only pointed them out. The "real" was not to him, as to Hegel, one with the "rational." Darwin has, indeed, by his whole conception of nature, rendered a great service to ethics in making the difference between the life of nature and the ethical life appear in so strong a light. The ethical problem could now be stated in a sharper form than before. But this was not the first time that the idea of the struggle for life was put in relation to the ethical problem. In the seventeenth century Thomas Hobbes gave the first impulse to the whole modern discussion of ethical principles in his theory of bellum omnium contra omnes. Men, he taught, are in the state of nature enemies one of another, and they live either in fright or in the glory of power. But it was not the opinion of Hobbes that this made ethics impossible. On the contrary, he found a standard for virtue and vice in the fact that some qualities and actions have a tendency to bring us out of the state of war and to secure peace, while other qualities have a contrary tendency. In the eighteenth century even Immanuel Kant's ideal ethics had--so far as can be seen--a similar origin. Shortly before the foundation of his definitive ethics, Kant wrote his "Idee zu einer allgemeinen Weltgeschichte" (1784), where--in a way which reminds us of Hobbes, and is prophetic of Darwin--he describes the forward-driving power of struggle in the human world. It is here as with the struggle of the trees for light and air, through which they compete with one another in height. Anxiety about war can only be allayed by an ordinance which gives everyone his full liberty under acknowledgment of the equal liberty of others. And such ordinance and acknowledgment are also attributes of the content of the moral law, as Kant proclaimed it in the year after the publication of his essay (1785) (Cf. my "History of Modern Philosophy" (English translation London, 1900), I. pages 76-79.) Kant really came to his ethics by the way of evolution, though he afterwards disavowed it. Similarly the same line of thought may be traced in Hegel though it has been disguised in the form of speculative dialectics. ("Herrschaft und Knechtschaft", "Phanomenologie des Geistes", IV. A., Leiden, 1907.) And in Schopenhauer's theory of the blind will to live and its abrogation by the ethical feeling, which is founded on universal sympathy, we have a more individualistic form of the same idea. It was, then, not entirely a foreign point of view which Darwin introduced into ethical thought, even if we take no account of the poetical character of the word "struggle" and of the more direct adaptation, through the use and non-use of power, which Darwin also emphasised. In "The Descent of Man" he has devoted a special chapter ("The Descent of Man", Vol. I. Ch. iii.) to a discussion of the origin of the ethical consciousness. The characteristic expression of this consciousness he found, just as Kant did, in the idea of "ought"; it was the origin of this new idea which should be explained. His hypothesis was that the ethical "ought" has its origin in the social and parental instincts, which, as well as other instincts (e.g. the instinct of self-preservation), lie deeper than pleasure and pain. In many species, not least in the human species, these instincts are fostered by natural selection; and when the powers of memory and comparison are developed, so that single acts can be valued according to the claims of the deep social instinct, then consciousness of duty and remorse are possible. Blind instinct has developed to conscious ethical will. As already stated, Darwin, as a moral philosopher belongs to the school that was founded by Shaftesbury, and was afterwards represented by Hutcheson, Hume, Adam Smith, Comte and Spencer. His merit is, first, that he has given this tendency of thought a biological foundation, and that he has stamped on it a doughty character in showing that ethical ideas and sentiments, rightly conceived, are forces which are at work in the struggle for life. There are still many questions to solve. Not only does the ethical development within the human species contain features still unexplained (The works of Westermarck and Hobhouse throw new light on many of these features.); but we are confronted by the great problem whether after all a genetic historical theory can be of decisive importance here. To every consequent ethical consciousness there is a standard of value, a primordial value which determines the single ethical judgments as their last presupposition, and the "rightness" of this basis, the "value" of this value can as little be discussed as the "rationality" of our logical principles. There is here revealed a possibility of ethical scepticism which evolutionistic ethics (as well as intuitive or rationalistic ethics) has overlooked. No demonstration can show that the results of the ethical development are definitive and universal. We meet here again with the important opposition of systematisation and evolution. There will, I think, always be an open question here, though comparative ethics, of which we have so far only the first attempts, can do much to throw light on it. It would carry us too far to discuss all the philosophical works on ethics, which have been influenced directly or indirectly by evolutionism. I may, however, here refer to the book of C.M. Williams, "A Review of the Systems of Ethics founded on the Theory of Evolution" (New York and London, 1893.), in which, besides Darwin, the following authors are reviewed: Wallace, Haeckel, Spencer, Fiske, Rolph, Barratt, Stephen, Carneri, Hoffding, Gizycki, Alexander, Ree. As works which criticise evolutionistic ethics from an intuitive point of view and in an instructive way, may be cited: Guyau "La morale anglaise contemporaine" (Paris, 1879.), and Sorley, "Ethics of Naturalism". I will only mention some interesting contributions to ethical discussion which can be found in Darwinism besides the idea of struggle for life. The attention which Darwin has directed to variations has opened our eyes to the differences in human nature as well as in nature generally. There is here a fact of great importance for ethical thought, no matter from what ultimate premiss it starts. Only from a very abstract point of view can different individuals be treated in the same manner. The most eminent ethical thinkers, men such as Jeremy Bentham and Immanuel Kant, who discussed ethical questions from very opposite standpoints, agreed in regarding all men as equal in respect of ethical endowment. In regard to Bentham, Leslie Stephen remarks: "He is determined to be thoroughly empirical, to take men as he found them. But his utilitarianism supposed that men's views of happiness and utility were uniform and clear, and that all that was wanted was to show them the means by which their ends could be reached." ("English literature and society in the eighteenth century", London, 1904, page 187.) And Kant supposed that every man would find the "categorical imperative" in his consciousness, when he came to sober reflexion, and that all would have the same qualifications to follow it. But if continual variations, great or small, are going on in human nature, it is the duty of ethics to make allowance for them, both in making claims, and in valuing what is done. A new set of ethical problems have their origin here. (Cf. my paper, "The law of relativity in Ethics," "International Journal of Ethics", Vol. I. 1891, pages 37-62.) It is an interesting fact that Stuart Mill's book "On Liberty" appeared in the same year as "The Origin of Species". Though Mill agreed with Bentham about the original equality of all men's endowments, he regarded individual differences as a necessary result of physical and social influences, and he claimed that free play shall be allowed to differences of character so far as is possible without injury to other men. It is a condition of individual and social progress that a man's mode of action should be determined by his own character and not by tradition and custom, nor by abstract rules. This view was to be corroborated by the theory of Darwin. But here we have reached a point of view from which the criticism, which in recent years has often been directed against Darwin--that small variations are of no importance in the struggle for life--is of no weight. From an ethical standpoint, and particularly from the ethical standpoint of Darwin himself, it is a duty to foster individual differences that can be valuable, even though they can neither be of service for physical preservation nor be physically inherited. The distinction between variation and mutation is here without importance. It is quite natural that biologists should be particularly interested in such variations as can be inherited and produce new species. But in the human world there is not only a physical, but also a mental and social heredity. When an ideal human character has taken form, then there is shaped a type, which through imitation and influence can become an important factor in subsequent development, even if it cannot form a species in the biological sense of the word. Spiritually strong men often succumb in the physical struggle for life; but they can nevertheless be victorious through the typical influence they exert, perhaps on very distant generations, if the remembrance of them is kept alive, be it in legendary or in historical form. Their very failure can show that a type has taken form which is maintained at all risks, a standard of life which is adhered to in spite of the strongest opposition. The question "to be or not to be" can be put from very different levels of being: it has too often been considered a consequence of Darwinism that this question is only to be put from the lowest level. When a stage is reached, where ideal (ethical, intellectual, aesthetic) interests are concerned, the struggle for life is a struggle for the preservation of this stage. The giving up of a higher standard of life is a sort of death; for there is not only a physical, there is also a spiritual, death. VI. The Socratic character of Darwin's mind appears in his wariness in drawing the last consequences of his doctrine, in contrast both with the audacious theories of so many of his followers and with the consequences which his antagonists were busy in drawing. Though he, as we have seen, saw from the beginning that his hypothesis would occasion "a whole of metaphysics," he was himself very reserved as to the ultimate questions, and his answers to such questions were extorted from him. As to the question of optimism and pessimism, Darwin held that though pain and suffering were very often the ways by which animals were led to pursue that course of action which is most beneficial to the species, yet pleasurable feelings were the most habitual guides. "We see this in the pleasure from exertion, even occasionally from great exertion of the body or mind, in the pleasure of our daily meals, and especially in the pleasure derived from sociability, and from loving our families." But there was to him so much suffering in the world that it was a strong argument against the existence of an intelligent First Cause. ("Life and Letters" Vol. I. page 310.) It seems to me that Darwin was not so clear on another question, that of the relation between improvement and adaptation. He wrote to Lyell: "When you contrast natural selection and 'improvement,' you seem always to overlook... that every step in the natural selection of each species implies improvement in that species IN RELATION TO ITS CONDITION OF LIFE... Improvement implies, I suppose, EACH FORM OBTAINING MANY PARTS OR ORGANS, all excellently adapted for their functions." "All this," he adds, "seems to me quite compatible with certain forms fitted for simple conditions, remaining unaltered, or being degraded." (Ibid. Vol. II. page 177.) But the great question is, if the conditions of life will in the long run favour "improvement" in the sense of differentiation (or harmony of differentiation and integration). Many beings are best adapted to their conditions of life if they have few organs and few necessities. Pessimism would not only be the consequence, if suffering outweighed happiness, but also if the most elementary forms of happiness were predominant, or if there were a tendency to reduce the standard of life to the simplest possible, the contentment of inertia or stable equilibrium. There are animals which are very highly differentiated and active in their young state, but later lose their complex organisation and concentrate themselves on the one function of nutrition. In the human world analogies to this sort of adaptation are not wanting. Young "idealists" very often end as old "Philistines." Adaptation and progress are not the same. Another question of great importance in respect to human evolution is, whether there will be always a possibility for the existence of an impulse to progress, an impulse to make great claims on life, to be active and to alter the conditions of life instead of adapting to them in a passive manner. Many people do not develop because they have too few necessities, and because they have no power to imagine other conditions of life than those under which they live. In his remarks on "the pleasure from exertion" Darwin has a point of contact with the practical idealism of former times--with the ideas of Lessing and Goethe, of Condorcet and Fichte. The continual striving which was the condition of salvation to Faust's soul, is also the condition of salvation to mankind. There is a holy fire which we ought to keep burning, if adaptation is really to be improvement. If, as I have tried to show in my "Philosophy of Religion", the innermost core of all religion is faith in the persistence of value in the world, and if the highest values express themselves in the cry "Excelsior!" then the capital point is, that this cry should always be heard and followed. We have here a corollary of the theory of evolution in its application to human life. Darwin declared himself an agnostic, not only because he could not harmonise the large amount of suffering in the world with the idea of a God as its first cause, but also because he "was aware that if we admit a first cause, the mind still craves to know whence it came and how it arose." ("Life and Letters", Vol. I. page 306.) He saw, as Kant had seen before him and expressed in his "Kritik der Urtheilskraft", that we cannot accept either of the only two possibilities which we are able to conceive: chance (or brute force) and design. Neither mechanism nor teleology can give an absolute answer to ultimate questions. The universe, and especially the organic life in it, can neither be explained as a mere combination of absolute elements nor as the effect of a constructing thought. Darwin concluded, as Kant, and before him Spinoza, that the oppositions and distinctions which our experience presents, cannot safely be regarded as valid for existence in itself. And, with Kant and Fichte, he found his stronghold in the conviction that man has something to do, even if he cannot solve all enigmas. "The safest conclusion seems to me that the whole subject is beyond the scope of man's intellect; but man can do his duty." (Ibid. page 307.) Is this the last word of human thought? Does not the possibility, that man can do his duty, suppose that the conditions of life allow of continuous ethical striving, so that there is a certain harmony between cosmic order and human ideals? Darwin himself has shown how the consciousness of duty can arise as a natural result of evolution. Moreover there are lines of evolution which have their end in ethical idealism, in a kingdom of values, which must struggle for life as all things in the world must do, but a kingdom which has its firm foundation in reality. XXIII. DARWINISM AND SOCIOLOGY. By C. Bougle. Professor of Social Philosophy in the University of Toulouse and Deputy-Professor at the Sorbonne, Paris. How has our conception of social phenomena, and of their history, been affected by Darwin's conception of Nature and the laws of its transformations? To what extent and in what particular respects have the discoveries and hypotheses of the author of "The Origin of Species" aided the efforts of those who have sought to construct a science of society? To such a question it is certainly not easy to give any brief or precise answer. We find traces of Darwinism almost everywhere. Sociological systems differing widely from each other have laid claim to its authority; while, on the other hand, its influence has often made itself felt only in combination with other influences. The Darwinian thread is worked into a hundred patterns along with other threads. To deal with the problem, we must, it seems, first of all distinguish the more general conclusions in regard to the evolution of living beings, which are the outcome of Darwinism, from the particular explanations it offers of the ways and means by which that evolution is effected. That is to say, we must, as far as possible, estimate separately the influence of Darwin as an evolutionist and Darwin as a selectionist. The nineteenth century, said Cournot, has witnessed a mighty effort to "reintegrer l'homme dans la nature." From divers quarters there has been a methodical reaction against the persistent dualism of the Cartesian tradition, which was itself the unconscious heir of the Christian tradition. Even the philosophy of the eighteenth century, materialistic as were for the most part the tendencies of its leaders, seemed to revere man as a being apart, concerning whom laws might be formulated a priori. To bring him down from his pedestal there was needed the marked predominance of positive researches wherein no account was taken of the "pride of man." There can be no doubt that Darwin has done much to familiarise us with this attitude. Take for instance the first part of "The Descent of Man": it is an accumulation of typical facts, all tending to diminish the distance between us and our brothers, the lower animals. One might say that the naturalist had here taken as his motto, "Whosoever shall exalt himself shall be abased; and he that shall humble himself shall be exalted." Homologous structures, the survival in man of certain organs of animals, the rudiments in the animal of certain human faculties, a multitude of facts of this sort, led Darwin to the conclusion that there is no ground for supposing that the "king of the universe" is exempt from universal laws. Thus belief in the imperium in imperio has been, as it were, whittled away by the progress of the naturalistic spirit, itself continually strengthened by the conquests of the natural sciences. The tendency may, indeed, drag the social sciences into overstrained analogies, such, for instance, as the assimilation of societies to organisms. But it will, at least, have had the merit of helping sociology to shake off the pre-conception that the groups formed by men are artificial, and that history is completely at the mercy of chance. Some years before the appearance of "The Origin of Species", Auguste Comte had pointed out the importance, as regards the unification of positive knowledge, of the conviction that the social world, the last refuge of spiritualism, is itself subject to determininism. It cannot be doubted that the movement of thought which Darwin's discoveries promoted contributed to the spread of this conviction, by breaking down the traditional barrier which cut man off from Nature. But Nature, according to modern naturalists, is no immutable thing: it is rather perpetual movement, continual progression. Their discoveries batter a breach directly into the Aristotelian notion of species; they refuse to see in the animal world a collection of immutable types, distinct from all eternity, and corresponding, as Cuvier said, to so many particular thoughts of the Creator. Darwin especially congratulated himself upon having been able to deal this doctrine the coup de grace: immutability is, he says, his chief enemy; and he is concerned to show--therein following up Lyell's work--that everything in the organic world, as in the inorganic, is explained by insensible but incessant transformations. "Nature makes no leaps"--"Nature knows no gaps": these two dicta form, as it were, the two landmarks between which Darwin's idea of transformation is worked out. That is to say, the development of Darwinism is calculated to further the application of the philosophy of Becoming to the study of human institutions. The progress of the natural sciences thus brings unexpected reinforcements to the revolution which the progress of historical discipline had begun. The first attempt to constitute an actual science of social phenomena--that, namely, of the economists--had resulted in laws which were called natural, and which were believed to be eternal and universal, valid for all times and all places. But this perpetuality, brother, as Knies said, of the immutability of the old zoology, did not long hold out against the ever swelling tide of the historical movement. Knowledge of the transformations that had taken place in language, of the early phases of the family, of religion, of property, had all favoured the revival of the Heraclitean view: panta rei. As to the categories of political economy, it was soon to be recognised, as by Lassalle, that they too are only historical. The philosophy of history, moreover, gave expression under various forms to the same tendency. Hegel declares that "all that is real is rational," but at the same time he shows that all that is real is ephemeral, and that for history there is nothing fixed beneath the sun. It is this sense of universal evolution that Darwin came with fresh authority to enlarge. It was in the name of biological facts themselves that he taught us to see only slow metamorphoses in the history of institutions, and to be always on the outlook for survivals side by side with rudimentary forms. Anyone who reads "Primitive Culture", by Tylor,--a writer closely connected with Darwin--will be able to estimate the services which these cardinal ideas were to render to the social sciences when the age of comparative research had succeeded to that of a priori construction. Let us note, moreover, that the philosophy of Becoming in passing through the Darwinian biology became, as it were, filtered: it got rid of those traces of finalism, which, under different forms, it had preserved through all the systems of German Romanticism. Even in Herbert Spencer, it has been plausibly argued, one can detect something of that sort of mystic confidence in forces spontaneously directing life, which forms the very essence of those systems. But Darwin's observations were precisely calculated to render such an hypothesis futile. At first people may have failed to see this; and we call to mind the ponderous sarcasms of Flourens when he objected to the theory of Natural Selection that it attributed to nature a power of free choice. "Nature endowed with will! That was the final error of last century; but the nineteenth no longer deals in personifications." (P. Flourens, "Examen du Livre de M. Darwin sur l'Origine des Especes", page 53, Paris, 1864. See also Huxley, "Criticisms on the 'Origin of Species'", "Collected Essays", Vol. II, page 102, London, 1902.) In fact Darwin himself put his readers on their guard against the metaphors he was obliged to use. The processes by which he explains the survival of the fittest are far from affording any indication of the design of some transcendent breeder. Nor, if we look closely, do they even imply immanent effort in the animal; the sorting out can be brought about mechanically, simply by the action of the environment. In this connection Huxley could with good reason maintain that Darwin's originality consisted in showing how harmonies which hitherto had been taken to imply the agency of intelligence and will could be explained without any such intervention. So, when later on, objective sociology declares that, even when social phenomena are in question, all finalist preconceptions must be distrusted if a science is to be constituted, it is to Darwin that its thanks are due; he had long been clearing paths for it which lay well away from the old familiar road trodden by so many theories of evolution. This anti-finalist doctrine, when fully worked out, was, moreover, calculated to aid in the needful dissociation of two notions: that of evolution and that of progress. In application to society these had long been confounded; and, as a consequence, the general idea seemed to be that only one type of evolution was here possible. Do we not detect such a view in Comte's sociology, and perhaps even in Herbert Spencer's? Whoever, indeed, assumes an end for evolution is naturally inclined to think that only one road leads to that end. But those whose minds the Darwinian theory has enlightened are aware that the transformations of living beings depend primarily upon their conditions, and that it is these conditions which are the agents of selection from among individual variations. Hence, it immediately follows that transformations are not necessarily improvements. Here, Darwin's thought hesitated. Logically his theory proves, as Ray Lankester pointed out, that the struggle for existence may have as its outcome degeneration as well as amelioration: evolution may be regressive as well as progressive. Then, too--and this is especially to be borne in mind--each species takes its good where it finds it, seeks its own path and survives as best it can. Apply this notion to society and you arrive at the theory of multilinear evolution. Divergencies will no longer surprise you. You will be forewarned not to apply to all civilisations the same measure of progress, and you will recognise that types of evolution may differ just as social species themselves differ. Have we not here one of the conceptions which mark off sociology proper from the old philosophy of history? But if we are to estimate the influence of Darwinism upon sociological conceptions, we must not dwell only upon the way in which Darwin impressed the general notion of evolution upon the minds of thinkers. We must go into details. We must consider the influence of the particular theories by which he explained the mechanism of this evolution. The name of the author of "The Origin of Species" has been especially attached, as everyone knows, to the doctrines of "natural selection" and of "struggle for existence," completed by the notion of "individual variation." These doctrines were turned to account by very different schools of social philosophy. Pessimistic and optimistic, aristocratic and democratic, individualistic and socialistic systems were to war with each other for years by casting scraps of Darwinism at each other's heads. It was the spectacle of human contrivance that suggested to Darwin his conception of natural selection. It was in studying the methods of pigeon breeders that he divined the processes by which nature, in the absence of design, obtains analogous results in the differentiation of types. As soon as the importance of artificial selection in the transformation of species of animals was understood, reflection naturally turned to the human species, and the question arose, How far do men observe, in connection with themselves, those laws of which they make practical application in the case of animals? Here we come upon one of the ideas which guided the researches of Galton, Darwin's cousin. The author of "Inquiries into Human Faculty and its Development" ("Inquiries into Human Faculty", pages 1, 2, 3 sq., London, 1883.), has often expressed his surprise that, considering all the precautions taken, for example, in the breeding of horses, none whatever are taken in the breeding of the human species. It seems to be forgotten that the species suffers when the "fittest" are not able to perpetuate their type. Ritchie, in his "Darwinism and Politics" ("Darwinism and Politics" pages 9, 22, London, 1889.) reminds us of Darwin's remark that the institution of the peerage might be defended on the ground that peers, owing to the prestige they enjoy, are enabled to select as wives "the most beautiful and charming women out of the lower ranks." ("Life and Letters of Charles Darwin", II. page 385.) But, says Galton, it is as often as not "heiresses" that they pick out, and birth statistics seem to show that these are either less robust or less fecund than others. The truth is that considerations continue to preside over marriage which are entirely foreign to the improvement of type, much as this is a condition of general progress. Hence the importance of completing Odin's and De Candolle's statistics which are designed to show how characters are incorporated in organisms, how they are transmitted, how lost, and according to what law eugenic elements depart from the mean or return to it. But thinkers do not always content themselves with undertaking merely the minute researches which the idea of Selection suggests. They are eager to defend this or that thesis. In the name of this idea certain social anthropologists have recast the conception of the process of civilisation, and have affirmed that Social Selection generally works against the trend of Natural Selection. Vacher de Lapouge--following up an observation by Broca on the point--enumerates the various institutions, or customs, such as the celibacy of priests and military conscription, which cause elimination or sterilisation of the bearers of certain superior qualities, intellectual or physical. In a more general way he attacks the democratic movement, a movement, as P. Bourget says, which is "anti-physical" and contrary to the natural laws of progress; though it has been inspired "by the dreams of that most visionary of all centuries, the eighteenth." (V. de Lapouge, "Les Selections sociales", page 259, Paris, 1896.) The "Equality" which levels down and mixes (justly condemned, he holds, by the Comte de Gobineau), prevents the aristocracy of the blond dolichocephales from holding the position and playing the part which, in the interests of all, should belong to them. Otto Ammon, in his "Natural Selection in Man", and in "The Social Order and its Natural Bases" ("Die naturliche Auslese beim Menschen", Jena, 1893; "Die Gesellschaftsordnung und ihre naturlichen Grundlagen". "Entwurf einer Sozialanthropologie", Jena, 1896.), defended analogous doctrines in Germany; setting the curve representing frequency of talent over against that of income, he attempted to show that all democratic measures which aim at promoting the rise in the social scale of the talented are useless, if not dangerous; that they only increase the panmixia, to the great detriment of the species and of society. Among the aristocratic theories which Darwinism has thus inspired we must reckon that of Nietzsche. It is well known that in order to complete his philosophy he added biological studies to his philological; and more than once in his remarks upon the "Wille zur Macht" he definitely alludes to Darwin; though it must be confessed that it is generally in order to proclaim the in sufficiency of the processes by which Darwin seeks to explain the genesis of species. Nevertheless, Nietzsche's mind is completely possessed by an ideal of Selection. He, too, has a horror of panmixia. The naturalists' conception of "the fittest" is joined by him to that of the "hero" of romance to furnish a basis for his doctrine of the Superman. Let us hasten to add, moreover, that at the very moment when support was being sought in the theory of Selection for the various forms of the aristocratic doctrine, those same forms were being battered down on another side by means of that very theory. Attention was drawn to the fact that by virtue of the laws which Darwin himself had discovered isolation leads to etiolation. There is a risk that the privilege which withdraws the privileged elements of Society from competition will cause them to degenerate. In fact, Jacoby in his "Studies in Selection, in connexion with Heredity in Man", ("Etudes sur la Selection dans ses rapports avec l'heredite chez l'homme", Paris, page 481, 1881.), concludes that "sterility, mental debility, premature death and, finally, the extinction of the stock were not specially and exclusively the fate of sovereign dynasties; all privileged classes, all families in exclusively elevated positions share the fate of reigning families, although in a minor degree and in direct proportion to the loftiness of their social standing. From the mass of human beings spring individuals, families, races, which tend to raise themselves above the common level; painfully they climb the rugged heights, attain the summits of power, of wealth, of intelligence, of talent, and then, no sooner are they there than they topple down and disappear in gulfs of mental and physical degeneracy." The demographical researches of Hansen ("Die drei Bevolkerungsstufen", Munich, 1889.) (following up and completing Dumont's) tended, indeed, to show that urban as well as feudal aristocracies, burgher classes as well as noble castes, were liable to become effete. Hence it might well be concluded that the democratic movement, operating as it does to break down class barriers, was promoting instead of impeding human selection. So we see that, according to the point of view, very different conclusions have been drawn from the application of the Darwinian idea of Selection to human society. Darwin's other central idea, closely bound up with this, that, namely, of the "struggle for existence" also has been diversely utilised. But discussion has chiefly centered upon its signification. And while some endeavour to extend its application to everything, we find others trying to limit its range. The conception of a "struggle for existence" has in the present day been taken up into the social sciences from natural science, and adopted. But originally it descended from social science to natural. Darwin's law is, as he himself said, only Malthus' law generalised and extended to the animal world: a growing disproportion between the supply of food and the number of the living is the fatal order whence arises the necessity of universal struggle, a struggle which, to the great advantage of the species, allows only the best equipped individuals to survive. Nature is regarded by Huxley as an immense arena where all living beings are gladiators. ("Evolution and Ethics", page 200; "Collected Essays", Vol. IX, London, 1894.) Such a generalisation was well adapted to feed the stream of pessimistic thought; and it furnished to the apologists of war, in particular, new arguments, weighted with all the authority which in these days attaches to scientific deliverances. If people no longer say, as Bonald did, and Moltke after him, that war is a providential fact, they yet lay stress on the point that it is a natural fact. To the peace party Dragomirov's objection is urged that its attempts are contrary to the fundamental laws of nature, and that no sea wall can hold against breakers that come with such gathered force. But in yet another quarter Darwinism was represented as opposed to philanthropic intervention. The defenders of the orthodox political economy found in it support for their tenets. Since in the organic world universal struggle is the condition of progress, it seemed obvious that free competition must be allowed to reign unchecked in the economic world. Attempts to curb it were in the highest degree imprudent. The spirit of Liberalism here seemed in conformity with the trend of nature: in this respect, at least, contemporary naturalism, offspring of the discoveries of the nineteenth century, brought reinforcements to the individualist doctrine, begotten of the speculations of the eighteenth: but only, it appeared, to turn mankind away for ever from humanitarian dreams. Would those whom such conclusions repelled be content to oppose to nature's imperatives only the protests of the heart? There were some who declared, like Brunetiere, that the laws in question, valid though they might be for the animal kingdom, were not applicable to the human. And so a return was made to the classic dualism. This indeed seems to be the line that Huxley took, when, for instance, he opposed to the cosmic process an ethical process which was its reverse. But the number of thinkers whom this antithesis does not satisfy grows daily. Although the pessimism which claims authorisation from Darwin's doctrines is repugnant to them, they still are unable to accept the dualism which leaves a gulf between man and nature. And their endeavour is to link the two by showing that while Darwin's laws obtain in both kingdoms, the conditions of their application are not the same: their forms, and, consequently, their results, vary with the varying mediums in which the struggle of living beings takes place, with the means these beings have at disposal, with the ends even which they propose to themselves. Here we have the explanation of the fact that among determined opponents of war partisans of the "struggle for existence" can be found: there are disciples of Darwin in the peace party. Novicow, for example, admits the "combat universel" of which Le Dantec ("Les Luttes entre Societies humaines et leurs phases successives", Paris, 1893,) speaks; but he remarks that at different stages of evolution, at different stages of life the same weapons are not necessarily employed. Struggles of brute force, armed hand to hand conflicts, may have been a necessity in the early phases of human societies. Nowadays, although competition may remain inevitable and indispensable, it can assume milder forms. Economic rivalries, struggles between intellectual influences, suffice to stimulate progress: the processes which these admit are, in the actual state of civilisation, the only ones which attain their end without waste, the only ones logical. From one end to the other of the ladder of life, struggle is the order of the day; but more and more as the higher rungs are reached, it takes on characters which are proportionately more "humane." Reflections of this kind permit the introduction into the economic order of limitations to the doctrine of "laisser faire, laisser passer." This appeals, it is said, to the example of nature where creatures, left to themselves, struggle without truce and without mercy; but the fact is forgotten that upon industrial battlefields the conditions are different. The competitors here are not left simply to their natural energies: they are variously handicapped. A rich store of artificial resources exists in which some participate and others do not. The sides then are unequal; and as a consequence the result of the struggle is falsified. "In the animal world," said De Laveleye ("Le socialisme contemporain", page 384 (6th edition), Paris, 1891.), criticising Spencer, "the fate of each creature is determined by its individual qualities; whereas in civilised societies a man may obtain the highest position and the most beautiful wife because he is rich and well-born, although he may be ugly, idle or improvident; and then it is he who will perpetuate the species. The wealthy man, ill constituted, incapable, sickly, enjoys his riches and establishes his stock under the protection of the laws." Haycraft in England and Jentsch in Germany have strongly emphasised these "anomalies," which nevertheless are the rule. That is to say that even from a Darwinian point of view all social reforms can readily be justified which aim at diminishing, as Wallace said, inequalities at the start. But we can go further still. Whence comes the idea that all measures inspired by the sentiment of solidarity are contrary to Nature's trend? Observe her carefully, and she will not give lessons only in individualism. Side by side with the struggle for existence do we not find in operation what Lanessan calls "association for existence." Long ago, Espinas had drawn attention to "societies of animals," temporary or permanent, and to the kind of morality that arose in them. Since then, naturalists have often insisted upon the importance of various forms of symbiosis. Kropotkin in "Mutual Aid" has chosen to enumerate many examples of altruism furnished by animals to mankind. Geddes and Thomson went so far as to maintain that "Each of the greater steps of progress is in fact associated with an increased measure of subordination of individual competition to reproductive or social ends, and of interspecific competition to co-operative association." (Geddes and Thomson, "The Evolution of Sex", page 311, London, 1889.) Experience shows, according to Geddes, that the types which are fittest to surmount great obstacles are not so much those who engage in the fiercest competitive struggle for existence, as those who contrive to temper it. From all these observations there resulted, along with a limitation of Darwinian pessimism, some encouragement for the aspirations of the collectivists. And Darwin himself would, doubtless, have subscribed to these rectifications. He never insisted, like his rival, Wallace, upon the necessity of the solitary struggle of creatures in a state of nature, each for himself and against all. On the contrary, in "The Descent of Man", he pointed out the serviceableness of the social instincts, and corroborated Bagehot's statements when the latter, applying laws of physics to politics, showed the great advantage societies derived from intercourse and communion. Again, the theory of sexual evolution which makes the evolution of types depend increasingly upon preferences, judgments, mental factors, surely offers something to qualify what seems hard and brutal in the theory of natural selection. But, as often happens with disciples, the Darwinians had out-Darwined Darwin. The extravagancies of social Darwinism provoked a useful reaction; and thus people were led to seek, even in the animal kingdom, for facts of solidarity which would serve to justify humane effort. On quite another line, however, an attempt has been made to connect socialist tendencies with Darwinian principles. Marx and Darwin have been confronted; and writers have undertaken to show that the work of the German philosopher fell readily into line with that of the English naturalist and was a development of it. Such has been the endeavour of Ferri in Italy and of Woltmann in Germany, not to mention others. The founders of "scientific socialism" had, moreover, themselves thought of this reconciliation. They make more than one allusion to Darwin in works which appeared after 1859. And sometimes they use his theory to define by contrast their own ideal. They remark that the capitalist system, by giving free course to individual competition, ends indeed in a bellum omnium contra omnes; and they make it clear that Darwinism, thus understood, is as repugnant to them as to Duhring. But it is at the scientific and not at the moral point of view that they place themselves when they connect their economic history with Darwin's work. Thanks to this unifying hypothesis, they claim to have constructed--as Marx does in his preface to "Das Kapital"--a veritable natural history of social evolution. Engels speaks in praise of his friend Marx as having discovered the true mainspring of history hidden under the veil of idealism and sentimentalism, and as having proclaimed in the primum vivere the inevitableness of the struggle for existence. Marx himself, in "Das Kapital", indicated another analogy when he dwelt upon the importance of a general technology for the explanation of this psychology:--a history of tools which would be to social organs what Darwinism is to the organs of animal species. And the very importance they attach to tools, to apparatus, to machines, abundantly proves that neither Marx nor Engels were likely to forget the special characters which mark off the human world from the animal. The former always remains to a great extent an artificial world. Inventions change the face of its institutions. New modes of production revolutionise not only modes of government, but modes even of collective thought. Therefore it is that the evolution of society is controlled by laws special to it, of which the spectacle of nature offers no suggestion. If, however, even in this special sphere, it can still be urged that the evolution of the material conditions of society is in accord with Darwin's theory, it is because the influence of the methods of production is itself to be explained by the incessant strife of the various classes with each other. So that in the end Marx, like Darwin, finds the source of all progress in struggle. Both are grandsons of Heraclitus:--polemos pater panton. It sometimes happens, in these days, that the doctrine of revolutionary socialism is contrasted as rude and healthy with what may seem to be the enervating tendency of "solidarist" philanthropy: the apologists of the doctrine then pride themselves above all upon their faithfulness to Darwinian principles. So far we have been mainly concerned to show the use that social philosophies have made of the Darwinian laws for practical purposes: in order to orientate society towards their ideals each school tries to show that the authority of natural science is on its side. But even in the most objective of theories, those which systematically make abstraction of all political tendencies in order to study the social reality in itself, traces of Darwinism are readily to be found. Let us take for example Durkheim's theory of Division of Labour ("De la Division du Travail social", Paris, 1893.) The conclusions he derives from it are that whenever professional specialisation causes multiplication of distinct branches of activity, we get organic solidarity--implying differences--substituted for mechanical solidarity, based upon likenesses. The umbilical cord, as Marx said, which connects the individual consciousness with the collective consciousness is cut. The personality becomes more and more emancipated. But on what does this phenomenon, so big with consequences, itself depend? The author goes to social morphology for the answer: it is, he says, the growing density of population which brings with it this increasing differentiation of activities. But, again, why? Because the greater density, in thrusting men up against each other, augments the intensity of their competition for the means of existence; and for the problems which society thus has to face differentiation of functions presents itself as the gentlest solution. Here one sees that the writer borrows directly from Darwin. Competition is at its maximum between similars, Darwin had declared; different species, not laying claim to the same food, could more easily coexist. Here lay the explanation of the fact that upon the same oak hundreds of different insects might be found. Other things being equal, the same applies to society. He who finds some unadopted speciality possesses a means of his own for getting a living. It is by this division of their manifold tasks that men contrive not to crush each other. Here we obviously have a Darwinian law serving as intermediary in the explanation of that progress of division of labour which itself explains so much in the social evolution. And we might take another example, at the other end of the series of sociological systems. G. Tarde is a sociologist with the most pronounced anti-naturalistic views. He has attempted to show that all application of the laws of natural science to society is misleading. In his "Opposition Universelle" he has directly combatted all forms of sociological Darwinism. According to him the idea that the evolution of society can be traced on the same plan as the evolution of species is chimerical. Social evolution is at the mercy of all kinds of inventions, which by virtue of the laws of imitation modify, through individual to individual, through neighbourhood to neighbourhood, the general state of those beliefs and desires which are the only "quantities" whose variation matters to the sociologist. But, it may be rejoined, that however psychical the forces may be, they are none the less subject to Darwinian laws. They compete with each other; they struggle for the mastery of minds. Between types of ideas, as between organic forms, selection operates. And though it may be that these types are ushered into the arena by unexpected discoveries, we yet recognise in the psychological accidents, which Tarde places at the base of everything, near relatives of those small accidental variations upon which Darwin builds. Thus, accepting Tarde's own representations, it is quite possible to express in Darwinian terms, with the necessary transpositions, one of the most idealistic sociologies that have ever been constructed. These few examples suffice. They enable us to estimate the extent of the field of influence of Darwinism. It affects sociology not only through the agency of its advocates but through that of its opponents. The questionings to which it has given rise have proved no less fruitful than the solutions it has suggested. In short, few doctrines, in the history of social philosophy, will have produced on their passage a finer outcrop of ideas. XXIV. THE INFLUENCE OF DARWIN UPON RELIGIOUS THOUGHT. By P.N. Waggett, M.A., S.S.J.E. I. The object of this paper is first to point out certain elements of the Darwinian influence upon Religious thought, and then to show reason for the conclusion that it has been, from a Christian point of view, satisfactory. I shall not proceed further to urge that the Christian apologetic in relation to biology has been successful. A variety of opinions may be held on this question, without disturbing the conclusion that the movements of readjustment have been beneficial to those who remain Christians, and this by making them more Christian and not only more liberal. The theologians may sometimes have retreated, but there has been an advance of theology. I know that this account incurs the charge of optimism. It is not the worst that could be made. The influence has been limited in personal range, unequal, even divergent, in operation, and accompanied by the appearance of waste and mischievous products. The estimate which follows requires for due balance a full development of many qualifying considerations. For this I lack space, but I must at least distinguish my view from the popular one that our difficulties about religion and natural science have come to an end. Concerning the older questions about origins--the origin of the world, of species, of man, of reason, conscience, religion--a large measure of understanding has been reached by some thoughtful men. But meanwhile new questions have arisen, questions about conduct, regarding both the reality of morals and the rule of right action for individuals and societies. And these problems, still far from solution, may also be traced to the influence of Darwin. For they arise from the renewed attention to heredity, brought about by the search for the causes of variation, without which the study of the selection of variations has no sufficient basis. Even the existing understanding about origins is very far from universal. On these points there were always thoughtful men who denied the necessity of conflict, and there are still thoughtful men who deny the possibility of a truce. It must further be remembered that the earlier discussion now, as I hope to show, producing favourable results, created also for a time grave damage, not only in the disturbance of faith and the loss of men--a loss not repaired by a change in the currents of debate--but in what I believe to be a still more serious respect. I mean the introduction of a habit of facile and untested hypothesis in religious as in other departments of thought. Darwin is not responsible for this, but he is in part the cause of it. Great ideas are dangerous guests in narrow minds; and thus it has happened that Darwin--the most patient of scientific workers, in whom hypothesis waited upon research, or if it provisionally outstepped it did so only with the most scrupulously careful acknowledgment--has led smaller and less conscientious men in natural science, in history, and in theology to an over-eager confidence in probable conjecture and a loose grip upon the facts of experience. It is not too much to say that in many quarters the age of materialism was the least matter-of-fact age conceivable, and the age of science the age which showed least of the patient temper of inquiry. I have indicated, as shortly as I could, some losses and dangers which in a balanced account of Darwin's influence would be discussed at length. One other loss must be mentioned. It is a defect in our thought which, in some quarters, has by itself almost cancelled all the advantages secured. I mean the exaggerated emphasis on uniformity or continuity; the unwillingness to rest any part of faith or of our practical expectation upon anything that from any point of view can be called exceptional. The high degree of success reached by naturalists in tracing, or reasonably conjecturing, the small beginnings of great differences, has led the inconsiderate to believe that anything may in time become anything else. It is true that this exaggeration of the belief in uniformity has produced in turn its own perilous reaction. From refusing to believe whatever can be called exceptional, some have come to believe whatever can be called wonderful. But, on the whole, the discontinuous or highly various character of experience received for many years too little deliberate attention. The conception of uniformity which is a necessity of scientific description has been taken for the substance of history. We have accepted a postulate of scientific method as if it were a conclusion of scientific demonstration. In the name of a generalisation which, however just on the lines of a particular method, is the prize of a difficult exploit of reflexion, we have discarded the direct impressions of experience; or, perhaps it is more true to say, we have used for the criticism of alleged experiences a doctrine of uniformity which is only valid in the region of abstract science. For every science depends for its advance upon limitation of attention, upon the selection out of the whole content of consciousness of that part or aspect which is measurable by the method of the science. Accordingly there is a science of life which rightly displays the unity underlying all its manifestations. But there is another view of life, equally valid, and practically sometimes more important, which recognises the immediate and lasting effect of crisis, difference, and revolution. Our ardour for the demonstration of uniformity of process and of minute continuous change needs to be balanced by a recognition of the catastrophic element in experience, and also by a recognition of the exceptional significance for us of events which may be perfectly regular from an impersonal point of view. An exorbitant jealousy of miracle, revelation, and ultimate moral distinctions has been imported from evolutionary science into religious thought. And it has been a damaging influence, because it has taken men's attention from facts, and fixed them upon theories. II. With this acknowledgment of important drawbacks, requiring many words for their proper description, I proceed to indicate certain results of Darwin's doctrine which I believe to be in the long run wholly beneficial to Christian thought. These are: The encouragement in theology of that evolutionary method of observation and study, which has shaped all modern research: The recoil of Christian apologetics towards the ground of religious experience, a recoil produced by the pressure of scientific criticism upon other supports of faith: The restatement, or the recovery of ancient forms of statement, of the doctrines of Creation and of divine Design in Nature, consequent upon the discussion of evolution and of natural selection as its guiding factor. (1) The first of these is quite possibly the most important of all. It was well defined in a notable paper read by Dr Gore, now Bishop of Birmingham, to the Church Congress at Shrewsbury in 1896. We have learnt a new caution both in ascribing and in denying significance to items of evidence, in utterance or in event. There has been, as in art, a study of values, which secures perspective and solidity in our representation of facts. On the one hand, a given utterance or event cannot be drawn into evidence as if all items were of equal consequence, like sovereigns in a bag. The question whence and whither must be asked, and the particular thing measured as part of a series. Thus measured it is not less truly important, but it may be important in a lower degree. On the other hand, and for exactly the same reason, nothing that is real is unimportant. The "failures" are not mere mistakes. We see them, in St Augustine's words, as "scholar's faults which men praise in hope of fruit." We cannot safely trace the origin of the evolutionistic method to the influence of natural science. The view is tenable that theology led the way. Probably this is a case of alternate and reciprocal debt. Quite certainly the evolutionist method in theology, in Christian history, and in the estimate of scripture, has received vast reinforcement from biology, in which evolution has been the ever present and ever victorious conception. (2) The second effect named is the new willingness of Christian thinkers to take definite account of religious experience. This is related to Darwin through the general pressure upon religious faith of scientific criticism. The great advance of our knowledge of organisms has been an important element in the general advance of science. It has acted, by the varied requirements of the theory of organisms, upon all other branches of natural inquiry, and it held for a long time that leading place in public attention which is now occupied by speculative physics. Consequently it contributed largely to our present estimation of science as the supreme judge in all matters of inquiry (F.R. Tennant: "The Being of God in the light of Physical Science", in "Essays on some theological questions of the day". London, 1905.), to the supposed destruction of mystery and the disparagement of metaphysic which marked the last age, as well as to the just recommendation of scientific method in branches of learning where the direct acquisitions of natural science had no place. Besides this, the new application of the idea of law and mechanical regularity to the organic world seemed to rob faith of a kind of refuge. The romantics had, as Berthelot ("Evolutionisme et Platonisme", pages 45, 46, 47. Paris, 1908.) shows, appealed to life to redress the judgments drawn from mechanism. Now, in Spencer, evolution gave us a vitalist mechanic or mechanical vitalism, and the appeal seemed cut off. We may return to this point later when we consider evolution; at present I only endeavour to indicate that general pressure of scientific criticism which drove men of faith to seek the grounds of reassurance in a science of their own; in a method of experiment, of observation, of hypothesis checked by known facts. It is impossible for me to do more than glance across the threshold of this subject. But it is necessary to say that the method is in an elementary stage of revival. The imposing success that belongs to natural science is absent: we fall short of the unchallengeable unanimity of the Biologists on fundamentals. The experimental method with its sure repetitions cannot be applied to our subject-matter. But we have something like the observational method of palaeontology and geographical distribution; and in biology there are still men who think that the large examination of varieties by way of geography and the search of strata is as truly scientific, uses as genuinely the logical method of difference, and is as fruitful in sure conclusions as the quasi-chemical analysis of Mendelian laboratory work, of which last I desire to express my humble admiration. Religion also has its observational work in the larger and possibly more arduous manner. But the scientific work in religion makes its way through difficulties and dangers. We are far from having found the formula of its combination with the historical elements of our apologetic. It is exposed, therefore, to a damaging fire not only from unspiritualist psychology and pathology but also from the side of scholastic dogma. It is hard to admit on equal terms a partner to the old undivided rule of books and learning. With Charles Lamb, we cry in some distress, "must knowledge come to me, if it come at all, by some awkward experiment of intuition, and no longer by this familiar process of reading?" ("Essays of Elia", "New Year's Eve", page 41; Ainger's edition. London, 1899.) and we are answered that the old process has an imperishable value, only we have not yet made clear its connection with other contributions. And all the work is young, liable to be drawn into unprofitable excursions, side-tracked by self-deceit and pretence; and it fatally attracts, like the older mysticism, the curiosity and the expository powers of those least in sympathy with it, ready writers who, with all the air of extended research, have been content with narrow grounds for induction. There is a danger, besides, which accompanies even the most genuine work of this science and must be provided against by all its serious students. I mean the danger of unbalanced introspection both for individuals and for societies; of a preoccupation comparable to our modern social preoccupation with bodily health; of reflection upon mental states not accompanied by exercise and growth of the mental powers; the danger of contemplating will and neglecting work, of analysing conviction and not criticising evidence. Still, in spite of dangers and mistakes, the work remains full of hopeful indications, and, in the best examples (Such an example is given in Baron F. von Hugel's recently finished book, the result of thirty years' research: "The Mystical Element of Religion, as studied in Saint Catherine of Genoa and her Friends". London, 1908.), it is truly scientific in its determination to know the very truth, to tell what we think, not what we think we ought to think. (G. Tyrrell, in "Mediaevalism", has a chapter which is full of the important MORAL element in a scientific attitude. "The only infallible guardian of truth is the spirit of truthfulness." "Mediaevalism" page 182, London, 1908.), truly scientific in its employment of hypothesis and verification, and in growing conviction of the reality of its subject-matter through the repeated victories of a mastery which advances, like science, in the Baconian road of obedience. It is reasonable to hope that progress in this respect will be more rapid and sure when religious study enlists more men affected by scientific desire and endowed with scientific capacity. The class of investigating minds is a small one, possibly even smaller than that of reflecting minds. Very few persons at any period are able to find out anything whatever. There are few observers, few discoverers, few who even wish to discover truth. In how many societies the problems of philology which face every person who speaks English are left unattempted! And if the inquiring or the successfully inquiring class of minds is small, much smaller, of course, is the class of those possessing the scientific aptitude in an eminent degree. During the last age this most distinguished class was to a very great extent absorbed in the study of phenomena, a study which had fallen into arrears. For we stood possessed, in rudiment, of means of observation, means for travelling and acquisition, qualifying men for a larger knowledge than had yet been attempted. These were now to be directed with new accuracy and ardour upon the fabric and behaviour of the world of sense. Our debt to the great masters in physical science who overtook and almost out-stripped the task cannot be measured; and, under the honourable leadership of Ruskin, we may all well do penance if we have failed "in the respect due to their great powers of thought, or in the admiration due to the far scope of their discovery." ("Queen of the Air", Preface, page vii. London, 1906.) With what miraculous mental energy and divine good fortune--as Romans said of their soldiers--did our men of curiosity face the apparently impenetrable mysteries of nature! And how natural it was that immense accessions of knowledge, unrelated to the spiritual facts of life, should discredit Christian faith, by the apparent superiority of the new work to the feeble and unprogressive knowledge of Christian believers! The day is coming when men of this mental character and rank, of this curiosity, this energy and this good fortune in investigation, will be employed in opening mysteries of a spiritual nature. They will silence with masterful witness the over-confident denials of naturalism. They will be in danger of the widespread recognition which thirty years ago accompanied every utterance of Huxley, Tyndall, Spencer. They will contribute, in spite of adulation, to the advance of sober religious and moral science. And this result will be due to Darwin, first because by raising the dignity of natural science, he encouraged the development of the scientific mind; secondly because he gave to religious students the example of patient and ardent investigation; and thirdly because by the pressure of naturalistic criticism the religious have been driven to ascertain the causes of their own convictions, a work in which they were not without the sympathy of men of science. (The scientific rank of its writer justifies the insertion of the following letter from the late Sir John Burdon-Sanderson to me. In the lecture referred to I had described the methods of Professor Moseley in teaching Biology as affording a suggestion of the scientific treatment of religion.) Oxford, April 30, 1902. Dear Sir, I feel that I must express to you my thanks for the discourse which I had the pleasure of listening to yesterday afternoon. I do not mean to say that I was able to follow all that you said as to the identity of Method in the two fields of Science and Religion, but I recognise that the "mysticism" of which you spoke gives us the only way by which the two fields can be brought into relation. Among much that was memorable, nothing interested me more than what you said of Moseley. No one, I am sure, knew better than you the value of his teaching and in what that value consisted. Yours faithfully J. Burdon-Sanderson. 31-2.) In leaving the subject of scientific religious inquiry, I will only add that I do not believe it receives any important help--and certainly it suffers incidentally much damaging interruption--from the study of abnormal manifestations or abnormal conditions of personality. (3) Both of the above effects seem to me of high, perhaps the very highest, importance to faith and to thought. But, under the third head, I name two which are more directly traceable to the personal work of Darwin, and more definitely characteristic of the age in which his influence was paramount: viz. the influence of the two conceptions of evolution and natural selection upon the doctrine of creation and of design respectively. It is impossible here, though it is necessary for a complete sketch of the matter, to distinguish the different elements and channels of this Darwinian influence; in Darwin's own writings, in the vigorous polemic of Huxley, and strangely enough, but very actually for popular thought, in the teaching of the definitely anti-Darwinian evolutionist Spencer. Under the head of the directly and purely Darwinian elements I should class as preeminent the work of Wallace and of Bates; for no two sets of facts have done more to fix in ordinary intelligent minds a belief in organic evolution and in natural selection as its guiding factor than the facts of geographical distribution and of protective colour and mimicry. The facts of geology were difficult to grasp and the public and theologians heard more often of the imperfection than of the extent of the geological record. The witness of embryology, depending to a great extent upon microscopic work, was and is beyond the appreciation of persons occupied in fields of work other than biology. III. From the influence in religion of scientific modes of thought we pass to the influence of particular biological conceptions. The former effect comes by way of analogy, example, encouragement and challenge; inspiring or provoking kindred or similar modes of thought in the field of theology; the latter by a collision of opinions upon matters of fact or conjecture which seem to concern both science and religion. In the case of Darwinism the story of this collision is familiar, and falls under the heads of evolution and natural selection, the doctrine of descent with modification, and the doctrine of its guidance or determination by the struggle for existence between related varieties. These doctrines, though associated and interdependent, and in popular thought not only combined but confused, must be considered separately. It is true that the ancient doctrine of Evolution, in spite of the ingenuity and ardour of Lamarck, remained a dream tantalising the intellectual ambition of naturalists, until the day when Darwin made it conceivable by suggesting the machinery of its guidance. And, further, the idea of natural selection has so effectively opened the door of research and stimulated observation in a score of principal directions that, even if the Darwinian explanation became one day much less convincing than, in spite of recent criticism, it now is, yet its passing, supposing it to pass, would leave the doctrine of Evolution immeasurably and permanently strengthened. For in the interests of the theory of selection, "Fur Darwin," as Muller wrote, facts have been collected which remain in any case evidence of the reality of descent with modification. But still, though thus united in the modern history of convictions, though united and confused in the collision of biological and traditional opinion, yet evolution and natural selection must be separated in theological no less than in biological estimation. Evolution seemed inconsistent with Creation; natural selection with Providence and Divine design. Discussion was maintained about these points for many years and with much dark heat. It ranged over many particular topics and engaged minds different in tone, in quality, and in accomplishment. There was at most times a degree of misconception. Some naturalists attributed to theologians in general a poverty of thought which belonged really to men of a particular temper or training. The "timid theism" discerned in Darwin by so cautious a theologian as Liddon (H.P. Liddon, "The Recovery of S. Thomas"; a sermon preached in St Paul's, London, on April 23rd, 1882 (the Sunday after Darwin's death).) was supposed by many biologists to be the necessary foundation of an honest Christianity. It was really more characteristic of devout NATURALISTS like Philip Henry Gosse, than of religious believers as such. (Dr Pusey ("Unscience not Science adverse to Faith" 1878) writes: "The questions as to 'species,' of what variations the animal world is capable, whether the species be more or fewer, whether accidental variations may become hereditary... and the like, naturally fall under the province of science. In all these questions Mr Darwin's careful observations gained for him a deserved approbation and confidence.") The study of theologians more considerable and even more typically conservative than Liddon does not confirm the description of religious intolerance given in good faith, but in serious ignorance, by a disputant so acute, so observant and so candid as Huxley. Something hid from each other's knowledge the devoted pilgrims in two great ways of thought. The truth may be, that naturalists took their view of what creation was from Christian men of science who naturally looked in their own special studies for the supports and illustrations of their religious belief. Of almost every laborious student it may be said "Hic ab arte sua non recessit." And both the believing and the denying naturalists, confining habitual attention to a part of experience, are apt to affirm and deny with trenchant vigour and something of a narrow clearness "Qui respiciunt ad pauca, de facili pronunciant." (Aristotle, in Bacon, quoted by Newman in his "Idea of a University", page 78. London, 1873.) Newman says of some secular teachers that "they persuade the world of what is false by urging upon it what is true." Of some early opponents of Darwin it might be said by a candid friend that, in all sincerity of devotion to truth, they tried to persuade the world of what is true by urging upon it what is false. If naturalists took their version of orthodoxy from amateurs in theology, some conservative Christians, instead of learning what evolution meant to its regular exponents, took their view of it from celebrated persons, not of the front rank in theology or in thought, but eager to take account of public movements and able to arrest public attention. Cleverness and eloquence on both sides certainly had their share in producing the very great and general disturbance of men's minds in the early days of Darwinian teaching. But by far the greater part of that disturbance was due to the practical novelty and the profound importance of the teaching itself, and to the fact that the controversy about evolution quickly became much more public than any controversy of equal seriousness had been for many generations. We must not think lightly of that great disturbance because it has, in some real sense, done its work, and because it is impossible in days of more coolness and light, to recover a full sense of its very real difficulties. Those who would know them better should add to the calm records of Darwin ("Life and Letters" and "More Letters of Charles Darwin".) and to the story of Huxley's impassioned championship, all that they can learn of George Romanes. ("Life and Letters", London, 1896. "Thoughts on Religion", London, 1895. "Candid Examination of Theism", London, 1878.) For his life was absorbed in this very struggle and reproduced its stages. It began in a certain assured simplicity of biblical interpretation; it went on, through the glories and adventures of a paladin in Darwin's train, to the darkness and dismay of a man who saw all his most cherished beliefs rendered, as he thought, incredible. ("Never in the history of man has so terrific a calamity befallen the race as that which all who look may now (viz. in consequence of the scientific victory of Darwin) behold advancing as a deluge, black with destruction, resistless in might, uprooting our most cherished hopes, engulphing our most precious creed, and burying our highest life in mindless destruction."--"A Candid Examination of Theism", page 51.) He lived to find the freer faith for which process and purpose are not irreconcilable, but necessary to one another. His development, scientific, intellectual and moral, was itself of high significance; and its record is of unique value to our own generation, so near the age of that doubt and yet so far from it; certainly still much in need of the caution and courage by which past endurance prepares men for new emergencies. We have little enough reason to be sure that in the discussions awaiting us we shall do as well as our predecessors in theirs. Remembering their endurance of mental pain, their ardour in mental labour, the heroic temper and the high sincerity of controversialists on either side, we may well speak of our fathers in such words of modesty and self-judgment as Drayton used when he sang the victors of Agincourt. The progress of biblical study, in the departments of Introduction and Exegesis, resulting in the recovery of a point of view anciently tolerated if not prevalent, has altered some of the conditions of that discussion. In the years near 1858, the witness of Scripture was adduced both by Christian advocates and their critics as if unmistakeably irreconcilable with Evolution. Huxley ("Science and Christian Tradition". London, 1904.) found the path of the blameless naturalist everywhere blocked by "Moses": the believer in revelation was generally held to be forced to a choice between revealed cosmogony and the scientific account of origins. It is not clear how far the change in Biblical interpretation is due to natural science, and how far to the vital movements of theological study which have been quite independent of the controversy about species. It belongs to a general renewal of Christian movement, the recovery of a heritage. "Special Creation"--really a biological rather than a theological conception,--seems in its rigid form to have been a recent element even in English biblical orthodoxy. The Middle Ages had no suspicion that religious faith forbad inquiry into the natural origination of the different forms of life. Bartholomaeus Anglicus, an English Franciscan of the thirteenth century, was a mutationist in his way, as Aristotle, "the Philosopher" of the Christian Schoolmen, had been in his. So late as the seventeenth century, as we learn not only from early proceedings of the Royal Society, but from a writer so homely and so regularly pious as Walton, the variation of species and "spontaneous" generations had no theological bearing, except as instances of that various wonder of the world which in devout minds is food for devotion. It was in the eighteenth century that the harder statement took shape. Something in the preciseness of that age, its exaltation of law, its cold passion for a stable and measured universe, its cold denial, its cold affirmation of the power of God, a God of ice, is the occasion of that rigidity of religious thought about the living world which Darwin by accident challenged, or rather by one of those movements of genius which, Goethe ("No productiveness of the highest kind... is in the power of anyone."--"Conversations of Goethe with Eckermann and Soret". London, 1850.) declares, are "elevated above all earthly control." If religious thought in the eighteenth century was aimed at a fixed and nearly finite world of spirit, it followed in all these respects the secular and critical lead. ("La philosophie reformatrice du XVIIIe siecle" (Berthelot, "Evolutionisme et Platonisme", Paris, 1908, page 45.) ramenait la nature et la societe a des mecanismes que la pensee reflechie peut concevoir et recomposer." In fact, religion in a mechanical age is condemned if it takes any but a mechanical tone. Butler's thought was too moving, too vital, too evolutionary, for the sceptics of his time. In a rationalist, encyclopaedic period, religion also must give hard outline to its facts, it must be able to display its secret to any sensible man in the language used by all sensible men. Milton's prophetic genius furnished the eighteenth century, out of the depth of the passionate age before it, with the theological tone it was to need. In spite of the austere magnificence of his devotion, he gives to smaller souls a dangerous lead. The rigidity of Scripture exegesis belonged to this stately but imperfectly sensitive mode of thought. It passed away with the influence of the older rationalists whose precise denials matched the precise and limited affirmations of the static orthodoxy. I shall, then, leave the specially biblical aspect of the debate--interesting as it is and even useful, as in Huxley's correspondence with the Duke of Argyll and others in 1892 ("Times", 1892, passim.)--in order to consider without complication the permanent elements of Christian thought brought into question by the teaching of evolution. Such permanent elements are the doctrine of God as Creator of the universe, and the doctrine of man as spiritual and unique. Upon both the doctrine of evolution seemed to fall with crushing force. With regard to Man I leave out, acknowledging a grave omission, the doctrine of the Fall and of Sin. And I do so because these have not yet, as I believe, been adequately treated: here the fruitful reaction to the stimulus of evolution is yet to come. The doctrine of sin, indeed, falls principally within the scope of that discussion which has followed or displaced the Darwinian; and without it the Fall cannot be usefully considered. For the question about the Fall is a question not merely of origins, but of the interpretation of moral facts whose moral reality must first be established. I confine myself therefore to Creation and the dignity of man. The meaning of evolution, in the most general terms, is that the differentiation of forms is not essentially separate from their behaviour and use; that if these are within the scope of study, that is also; that the world has taken the form we see by movements not unlike those we now see in progress; that what may be called proximate origins are continuous in the way of force and matter, continuous in the way of life, with actual occurrences and actual characteristics. All this has no revolutionary bearing upon the question of ultimate origins. The whole is a statement about process. It says nothing to metaphysicians about cause. It simply brings within the scope of observation or conjecture that series of changes which has given their special characters to the different parts of the world we see. In particular, evolutionary science aspires to the discovery of the process or order of the appearance of life itself: if it were to achieve its aim it could say nothing of the cause of this or indeed of the most familiar occurrences. We should have become spectators or convinced historians of an event which, in respect of its cause and ultimate meaning, would be still impenetrable. With regard to the origin of species, supposing life already established, biological science has the well founded hopes and the measure of success with which we are all familiar. All this has, it would seem, little chance of collision with a consistent theism, a doctrine which has its own difficulties unconnected with any particular view of order or process. But when it was stated that species had arisen by processes through which new species were still being made, evolutionism came into collision with a statement, traditionally religious, that species were formed and fixed once for all and long ago. What is the theological import of such a statement when it is regarded as essential to belief in God? Simply that God's activity, with respect to the formation of living creatures, ceased at some point in past time. "God rested" is made the touchstone of orthodoxy. And when, under the pressure of the evidences, we found ourselves obliged to acknowledge and assert the present and persistent power of God, in the maintenance and in the continued formation of "types," what happened was the abolition of a time-limit. We were forced only to a bolder claim, to a theistic language less halting, more consistent, more thorough in its own line, as well as better qualified to assimilate and modify such schemes as Von Hartmann's philosophy of the unconscious--a philosophy, by the way, quite intolerant of a merely mechanical evolution. (See Von Hartmann's "Wahrheit und Irrthum in Darwinismus". Berlin, 1875.) Here was not the retrenchment of an extravagant assertion, but the expansion of one which was faltering and inadequate. The traditional statement did not need paring down so as to pass the meshes of a new and exacting criticism. It was itself a net meant to surround and enclose experience; and we must increase its size and close its mesh to hold newly disclosed facts of life. The world, which had seemed a fixed picture or model, gained first perspective and then solidity and movement. We had a glimpse of organic HISTORY; and Christian thought became more living and more assured as it met the larger view of life. However unsatisfactory the new attitude might be to our critics, to Christians the reform was positive. What was discarded was a limitation, a negation. The movement was essentially conservative, even actually reconstructive. For the language disused was a language inconsistent with the definitions of orthodoxy; it set bounds to the infinite, and by implication withdrew from the creative rule all such processes as could be brought within the descriptions of research. It ascribed fixity and finality to that "creature" in which an apostle taught us to recognise the birth-struggles of an unexhausted progress. It tended to banish mystery from the world we see, and to confine it to a remote first age. In the reformed, the restored, language of religion, Creation became again not a link in a rational series to complete a circle of the sciences, but the mysterious and permanent relation between the infinite and the finite, between the moving changes we know in part, and the Power, after the fashion of that observation, unknown, which is itself "unmoved all motion's source." (Hymn of the Church-- Rerum Deus tenax vigor, Immotus in te permanens.) With regard to man it is hardly necessary, even were it possible, to illustrate the application of this bolder faith. When the record of his high extraction fell under dispute, we were driven to a contemplation of the whole of his life, rather than of a part and that part out of sight. We remembered again, out of Aristotle, that the result of a process interprets its beginnings. We were obliged to read the title of such dignity as we may claim, in results and still more in aspirations. Some men still measure the value of great present facts in life--reason and virtue and sacrifice--by what a self-disparaged reason can collect of the meaner rudiments of these noble gifts. Mr Balfour has admirably displayed the discrepancy, in this view, between the alleged origin and the alleged authority of reason. Such an argument ought to be used not to discredit the confident reason, but to illuminate and dignify its dark beginnings, and to show that at every step in the long course of growth a Power was at work which is not included in any term or in all the terms of the series. I submit that the more men know of actual Christian teaching, its fidelity to the past, and its sincerity in face of discovery, the more certainly they will judge that the stimulus of the doctrine of evolution has produced in the long run vigour as well as flexibility in the doctrine of Creation and of man. I pass from Evolution in general to Natural Selection. The character in religious language which I have for short called mechanical was not absent in the argument from design as stated before Darwin. It seemed to have reference to a world conceived as fixed. It pointed, not to the plastic capacity and energy of living matter, but to the fixed adaptation of this and that organ to an unchanging place or function. Mr Hobhouse has given us the valuable phrase "a niche of organic opportunity." Such a phrase would have borne a different sense in non-evolutionary thought. In that thought, the opportunity was an opportunity for the Creative Power, and Design appeared in the preparation of the organism to fit the niche. The idea of the niche and its occupant growing together from simpler to more complex mutual adjustment was unwelcome to this teleology. If the adaptation was traced to the influence, through competition, of the environment, the old teleology lost an illustration and a proof. For the cogency of the proof in every instance depended upon the absence of explanation. Where the process of adaptation was discerned, the evidence of Purpose or Design was weak. It was strong only when the natural antecedents were not discovered, strongest when they could be declared undiscoverable. Paley's favourite word is "Contrivance"; and for him contrivance is most certain where production is most obscure. He points out the physiological advantage of the valvulae conniventes to man, and the advantage for teleology of the fact that they cannot have been formed by "action and pressure." What is not due to pressure may be attributed to design, and when a "mechanical" process more subtle than pressure was suggested, the case for design was so far weakened. The cumulative proof from the multitude of instances began to disappear when, in selection, a natural sequence was suggested in which all the adaptations might be reached by the motive power of life, and especially when, as in Darwin's teaching, there was full recognition of the reactions of life to the stimulus of circumstance. "The organism fits the niche," said the teleologist, "because the Creator formed it so as to fit." "The organism fits the niche," said the naturalist, "because unless it fitted it could not exist." "It was fitted to survive," said the theologian. "It survives because it fits," said the selectionist. The two forms of statement are not incompatible; but the new statement, by provision of an ideally universal explanation of process, was hostile to a doctrine of purpose which relied upon evidences always exceptional however numerous. Science persistently presses on to find the universal machinery of adaptation in this planet; and whether this be found in selection, or in direct-effect, or in vital reactions resulting in large changes, or in a combination of these and other factors, it must always be opposed to the conception of a Divine Power here and there but not everywhere active. For science, the Divine must be constant, operative everywhere and in every quality and power, in environment and in organism, in stimulus and in reaction, in variation and in struggle, in hereditary equilibrium, and in "the unstable state of species"; equally present on both sides of every strain, in all pressures and in all resistances, in short in the general wonder of life and the world. And this is exactly what the Divine Power must be for religious faith. The point I wish once more to make is that the necessary readjustment of teleology, so as to make it depend upon the contemplation of the whole instead of a part, is advantageous quite as much to theology as to science. For the older view failed in courage. Here again our theism was not sufficiently theistic. Where results seemed inevitable, it dared not claim them as God-given. In the argument from Design it spoke not of God in the sense of theology, but of a Contriver, immensely, not infinitely wise and good, working within a world, the scene, rather than the ever dependent outcome, of His Wisdom; working in such emergencies and opportunities as occurred, by forces not altogether within His control, towards an end beyond Himself. It gave us, instead of the awful reverence due to the Cause of all substance and form, all love and wisdom, a dangerously detached appreciation of an ingenuity and benevolence meritorious in aim and often surprisingly successful in contrivance. The old teleology was more useful to science than to religion, and the design-naturalists ought to be gratefully remembered by Biologists. Their search for evidences led them to an eager study of adaptations and of minute forms, a study such as we have now an incentive to in the theory of Natural Selection. One hardly meets with the same ardour in microscopical research until we come to modern workers. But the argument from Design was never of great importance to faith. Still, to rid it of this character was worth all the stress and anxiety of the gallant old war. If Darwin had done nothing else for us, we are to-day deeply in his debt for this. The world is not less venerable to us now, not less eloquent of the causing mind, rather much more eloquent and sacred. But our wonder is not that "the underjaw of the swine works under the ground" or in any or all of those particular adaptations which Paley collected with so much skill, but that a purpose transcending, though resembling, our own purposes, is everywhere manifest; that what we live in is a whole, mutually sustaining, eventful and beautiful, where the "dead" forces feed the energies of life, and life sustains a stranger existence, able in some real measure to contemplate the whole, of which, mechanically considered, it is a minor product and a rare ingredient. Here, again, the change was altogether positive. It was not the escape of a vessel in a storm with loss of spars and rigging, not a shortening of sail to save the masts and make a port of refuge. It was rather the emergence from narrow channels to an open sea. We had propelled the great ship, finding purchase here and there for slow and uncertain movement. Now, in deep water, we spread large canvas to a favouring breeze. The scattered traces of design might be forgotten or obliterated. But the broad impression of Order became plainer when seen at due distance and in sufficient range of effect, and the evidence of love and wisdom in the universe could be trusted more securely for the loss of the particular calculation of their machinery. Many other topics of faith are affected by modern biology. In some of these we have learnt at present only a wise caution, a wise uncertainty. We stand before the newly unfolded spectacle of suffering, silenced; with faith not scientifically reassured but still holding fast certain other clues of conviction. In many important topics we are at a loss. But in others, and among them those I have mentioned, we have passed beyond this negative state and find faith positively strengthened and more fully expressed. We have gained also a language and a habit of thought more fit for the great and dark problems that remain, less liable to damaging conflicts, equipped for more rapid assimilation of knowledge. And by this change biology itself is a gainer. For, relieved of fruitless encounters with popular religion, it may advance with surer aim along the path of really scientific life-study which was reopened for modern men by the publication of "The Origin of Species". Charles Darwin regretted that, in following science, he had not done "more direct good" ("Life and Letters", Vol. III. page 359.) to his fellow-creatures. He has, in fact, rendered substantial service to interests bound up with the daily conduct and hopes of common men; for his work has led to improvements in the preaching of the Christian faith. XXV. THE INFLUENCE OF DARWINISM ON THE STUDY OF RELIGIONS. By Jane Ellen Harrison. Hon. D.Litt. (Durham), Hon. LL.D. (Aberdeen), Staff Lecturer and sometime Fellow of Newnham College, Cambridge. Corresponding member of the German Archaeological Institute. The title of my paper might well have been "the creation by Darwinism of the scientific study of Religions," but that I feared to mar my tribute to a great name by any shadow of exaggeration. Before the publication of "The Origin of Species" and "The Descent of Man", even in the eighteenth century, isolated thinkers, notably Hume and Herder, had conjectured that the orthodox beliefs of their own day were developments from the cruder superstitions of the past. These were however only particular speculations of individual sceptics. Religion was not yet generally regarded as a proper subject for scientific study, with facts to be collected and theories to be deduced. A Congress of Religions such as that recently held at Oxford would have savoured of impiety. In the brief space allotted me I can attempt only two things; first, and very briefly, I shall try to indicate the normal attitude towards religion in the early part of the last century; second, and in more detail, I shall try to make clear what is the outlook of advanced thinkers to-day. (To be accurate I ought to add "in Europe." I advisedly omit from consideration the whole immense field of Oriental mysticism, because it has remained practically untouched by the influence of Darwinism.) From this second inquiry it will, I hope, be abundantly manifest that it is the doctrine of evolution that has made this outlook possible and even necessary. The ultimate and unchallenged presupposition of the old view was that religion was a DOCTRINE, a body of supposed truths. It was in fact what we should now call Theology, and what the ancients called Mythology. Ritual was scarcely considered at all, and, when considered, it was held to be a form in which beliefs, already defined and fixed as dogma, found a natural mode of expression. This, it will be later shown, is a profound error or rather a most misleading half-truth. Creeds, doctrines, theology and the like are only a part, and at first the least important part, of religion. Further, and the fact is important, this DOGMA, thus supposed to be the essential content of the "true" religion, was a teleological scheme complete and unalterable, which had been revealed to man once and for all by a highly anthropomorphic God, whose existence was assumed. The duty of man towards this revelation was to accept its doctrines and obey its precepts. The notion that this revelation had grown bit by bit out of man's consciousness and that his business was to better it would have seemed rank blasphemy. Religion, so conceived, left no place for development. "The Truth" might be learnt, but never critically examined; being thus avowedly complete and final, it was doomed to stagnation. The details of this supposed revelation seem almost too naive for enumeration. As Hume observed, "popular theology has a positive appetite for absurdity." It is sufficient to recall that "revelation" included such items as the Creation (It is interesting to note that the very word "Creator" has nowadays almost passed into the region of mythology. Instead we have "L'Evolution Creatrice".) of the world out of nothing in six days; the making of Eve from one of Adam's ribs; the Temptation by a talking snake; the confusion of tongues at the tower of Babel; the doctrine of Original Sin; a scheme of salvation which demanded the Virgin Birth, Vicarious Atonement, and the Resurrection of the material body. The scheme was unfolded in an infallible Book, or, for one section of Christians, guarded by the tradition of an infallible Church, and on the acceptance or refusal of this scheme depended an eternity of weal or woe. There is not one of these doctrines that has not now been recast, softened down, mysticised, allegorised into something more conformable with modern thinking. It is hard for the present generation, unless their breeding has been singularly archaic, to realise that these amazing doctrines were literally held and believed to constitute the very essence of religion; to doubt them was a moral delinquency. It had not, however, escaped the notice of travellers and missionaries that savages carried on some sort of practices that seemed to be religious, and believed in some sort of spirits or demons. Hence, beyond the confines illuminated by revealed truth, a vague region was assigned to NATURAL Religion. The original revelation had been kept intact only by one chosen people, the Jews, by them to be handed on to Christianity. Outside the borders of this Goshen the world had sunk into the darkness of Egypt. Where analogies between savage cults and the Christian religions were observed, they were explained as degradations; the heathen had somehow wilfully "lost the light." Our business was not to study but, exclusively, to convert them, to root out superstition and carry the torch of revelation to "Souls in heathen darkness lying." To us nowadays it is a commonplace of anthropological research that we must seek for the beginnings of religion in the religions of primitive peoples, but in the last century the orthodox mind was convinced that it possessed a complete and luminous ready-made revelation; the study of what was held to be a mere degradation seemed idle and superfluous. But, it may be asked, if, to the orthodox, revealed religion was sacrosanct and savage religion a thing beneath consideration, why did not the sceptics show a more liberal spirit, and pursue to their logical issue the conjectures they had individually hazarded? The reason is simple and significant. The sceptics too had not worked free from the presupposition that the essence of religion is dogma. Their intellectualism, expressive of the whole eighteenth century, was probably in England strengthened by the Protestant doctrine of an infallible Book. Hume undoubtedly confused religion with dogmatic theology. The attention of orthodox and sceptics alike was focussed on the truth or falsity of certain propositions. Only a few minds of rare quality were able dimly to conceive that religion might be a necessary step in the evolution of human thought. It is not a little interesting to note that Darwin, who was leader and intellectual king of his generation, was also in this matter to some extent its child. His attitude towards religion is stated clearly, in Chapter VIII. of the "Life and Letters". (Vol. I. page 304. For Darwin's religious views see also "Descent of Man", 1871, Vol. I. page 65; 2nd edition. Vol. I. page 142.) On board the "Beagle" he was simply orthodox and was laughed at by several of the officers for quoting the Bible as an unanswerable authority on some point of morality. By 1839 he had come to see that the Old Testament was no more to be trusted than the sacred books of the Hindoos. Next went the belief in miracles, and next Paley's "argument from design" broke down before the law of natural selection; the suffering so manifest in nature is seen to be compatible rather with Natural Selection than with the goodness and omnipotence of God. Darwin felt to the full all the ignorance that lay hidden under specious phrases like "the plan of creation" and "Unity of design." Finally, he tells us "the mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an Agnostic." The word Agnostic is significant not only of the humility of the man himself but also of the attitude of his age. Religion, it is clear, is still conceived as something to be KNOWN, a matter of true or false OPINION. Orthodox religion was to Darwin a series of erroneous hypotheses to be bit by bit discarded when shown to be untenable. The ACTS of religion which may result from such convictions, i.e. devotion in all its forms, prayer, praise, sacraments, are left unmentioned. It is clear that they are not, as now to us, sociological survivals of great interest and importance, but rather matters too private, too personal, for discussion. Huxley, writing in the "Contemporary Review" (1871.), says, "In a dozen years "The Origin of Species" has worked as complete a revolution in biological science as the "Principia" did in astronomy." It has done so because, in the words of Helmholtz, it contained "an essentially new creative thought," that of the continuity of life, the absence of breaks. In the two most conservative subjects, Religion and Classics, this creative ferment was slow indeed to work. Darwin himself felt strongly "that a man should not publish on a subject to which he has not given special and continuous thought," and hence wrote little on religion and with manifest reluctance, though, as already seen, in answer to pertinacious inquiry he gave an outline of his own views. But none the less he foresaw that his doctrine must have, for the history of man's mental evolution, issues wider than those with which he was prepared personally to deal. He writes, in "The Origin of Species" (6th edition, page 428.), "In the future I see open fields for far more important researches. Psychology will be securely based on the foundation already well laid by Mr Herbert Spencer, that of the necessary acquirement of each mental power and capacity by gradation." Nowhere, it is true, does Darwin definitely say that he regarded religion as a set of phenomena, the development of which may be studied from the psychological standpoint. Rather we infer from his PIETY--in the beautiful Roman sense--towards tradition and association, that religion was to him in some way sacrosanct. But it is delightful to see how his heart went out towards the new method in religious study which he had himself, if half-unconsciously, inaugurated. Writing in 1871 to Dr Tylor, on the publication of his "Primitive Culture", he says ("Life and Letters", Vol. III. page 151.), "It is wonderful how you trace animism from the lower races up the religious belief of the highest races. It will make me for the future look at religion--a belief in the soul, etc.--from a new point of view." Psychology was henceforth to be based on "the necessary acquirement of each mental capacity by gradation." With these memorable words the door closes on the old and opens on the new horizon. The mental focus henceforth is not on the maintaining or refuting of an orthodoxy but on the genesis and evolution of a capacity, not on perfection but on process. Continuous evolution leaves no gap for revelation sudden and complete. We have henceforth to ask, not when was religion revealed or what was the revelation, but how did religious phenomena arise and develop. For an answer to this we turn with new and reverent eyes to study "the heathen in his blindness" and the child "born in sin." We still indeed send out missionaries to convert the heathen, but here at least in Cambridge before they start they attend lectures on anthropology and comparative religion. The "decadence" theory is dead and should be buried. The study of primitive religions then has been made possible and even inevitable by the theory of Evolution. We have now to ask what new facts and theories have resulted from that study. This brings us to our second point, the advanced outlook on religion to-day. The view I am about to state is no mere personal opinion of my own. To my present standpoint I have been led by the investigations of such masters as Drs Wundt, Lehmann, Preuss, Bergson, Beck and in our own country Drs Tylor and Frazer. (I can only name here the books that have specially influenced my own views. They are W. Wundt, "Volkerpsychologie", Leipzig, 1900, P. Beck, "Die Nachahmung", Leipzig, 1904, and "Erkenntnisstheorie des primitiven Denkens" in "Zeitschrift f. Philos. und Philos. Kritik", 1903, page 172, and 1904, page 9. Henri Bergson, "L'Evolution Creatrice" and "Matiere et Memoire", 1908, K. Th. Preuss, various articles published in the "Globus" (see page 507, note 1), and in the "Archiv. f. Religionswissenschaft", and for the subject of magic, MM. Hubert et Mauss, "Theorie generale de la Magie", in "L'Annee Sociologique", VII.) Religion always contains two factors. First, a theoretical factor, what a man THINKS about the unseen--his theology, or, if we prefer so to call it, his mythology. Second, what he DOES in relation to this unseen--his ritual. These factors rarely if ever occur in complete separation; they are blended in very varying proportions. Religion we have seen was in the last century regarded mainly in its theoretical aspect as a doctrine. Greek religion for example meant to most educated persons Greek mythology. Yet even a cursory examination shows that neither Greek nor Roman had any creed or dogma, any hard and fast formulation of belief. In the Greek Mysteries (See my "Prolegomena to the Study of Greek Religion", page 155, Cambridge, 1903.) only we find what we should call a Confiteor; and this is not a confession of faith, but an avowal of rites performed. When the religion of primitive peoples came to be examined it was speedily seen that though vague beliefs necessarily abound, definite creeds are practically non-existent. Ritual is dominant and imperative. This predominance and priority of ritual over definite creed was first forced upon our notice by the study of savages, but it promptly and happily joined hands with modern psychology. Popular belief says, I think, therefore I act; modern scientific psychology says, I act (or rather, REact to outside stimulus), and so I come to think. Thus there is set going a recurrent series: act and thought become in their turn stimuli to fresh acts and thoughts. In examining religion as envisaged to-day it would therefore be more correct to begin with the practice of religion, i.e. ritual, and then pass to its theory, theology or mythology. But it will be more convenient to adopt the reverse method. The theoretical content of religion is to those of us who are Protestants far more familiar and we shall thus proceed from the known to the comparatively unknown. I shall avoid all attempt at rigid definition. The problem before the modern investigator is, not to determine the essence and definition of religion but to inquire how religious phenomena, religious ideas and practices arose. Now the theoretical content of religion, the domain of theology or mythology, is broadly familiar to all. It is the world of the unseen, the supersensuous; it is the world of what we call the soul and the supposed objects of the soul's perception, sprites, demons, ghosts and gods. How did this world grow up? We turn to our savages. Intelligent missionaries of bygone days used to ply savages with questions such as these: Had they any belief in God? Did they believe in the immortality of the soul? Taking their own clear-cut conceptions, discriminated by a developed terminology, these missionaries tried to translate them into languages that had neither the words nor the thoughts, only a vague, inchoate, tangled substratum, out of which these thoughts and words later differentiated themselves. Let us examine this substratum. Nowadays we popularly distinguish between objective and subjective; and further, we regard the two worlds as in some sense opposed. To the objective world we commonly attribute some reality independent of consciousness, while we think of the subjective as dependent for its existence on the mind. The objective world consists of perceptible things, or of the ultimate constituents to which matter is reduced by physical speculation. The subjective world is the world of beliefs, hallucinations, dreams, abstract ideas, imaginations and the like. Psychology of course knows that the objective and subjective worlds are interdependent, inextricably intertwined, but for practical purposes the distinction is convenient. But primitive man has not yet drawn the distinction between objective and subjective. Nay, more, it is foreign to almost the whole of ancient philosophy. Plato's Ideas (I owe this psychological analysis of the elements of the primitive supersensuous world mainly to Dr Beck, "Erkenntnisstheorie des primitiven Denkens", see page 498, note 1.), his Goodness, Truth, Beauty, his class-names, horse, table, are it is true dematerialised as far as possible, but they have outside existence, apart from the mind of the thinker, they have in some shadowy way spatial extension. Yet ancient philosophies and primitive man alike needed and possessed for practical purposes a distinction which served as well as our subjective and objective. To the primitive savage all his thoughts, every object of which he was conscious, whether by perception or conception, had reality, that is, it had existence outside himself, but it might have reality of various kinds or different degrees. It is not hard to see how this would happen. A man's senses may mislead him. He sees the reflection of a bird in a pond. To his eyes it is a real bird. He touches it, HE PUTS IT TO THE TOUCH, and to his touch it is not a bird at all. It is real then, but surely not quite so real as a bird that you can touch. Again, he sees smoke. It is real to his eyes. He tries to grasp it, it vanishes. The wind touches him, but he cannot see it, which makes him feel uncanny. The most real thing is that which affects most senses and especially what affects the sense of touch. Apparently touch is the deepest down, most primitive, of senses. The rest are specialisations and complications. Primitive man has no formal rubric "optical delusion," but he learns practically to distinguish between things that affect only one sense and things that affect two or more--if he did not he would not survive. But both classes of things are real to him. Percipi est esse. So far, primitive man has made a real observation; there are things that appeal to one sense only. But very soon creeps in confusion fraught with disaster. He passes naturally enough, being economical of any mental effort, from what he really sees but cannot feel to what he thinks he sees, and gives to it the same secondary reality. He has dreams, visions, hallucinations, nightmares. He dreams that an enemy is beating him, and he wakes rubbing his head. Then further he remembers things; that is, for him, he sees them. A great chief died the other day and they buried him, but he sees him still in his mind, sees him in his war-paint, splendid, victorious. So the image of the past goes together with his dreams and visions to the making of this other less real, but still real world, his other-world of the supersensuous, the supernatural, a world, the outside existence of which, independent of himself, he never questions. And, naturally enough, the future joins the past in this supersensuous world. He can hope, he can imagine, he can prophesy. And again the images of his hope are real; he sees them with that mind's eye which as yet he has not distinguished from his bodily eye. And so the supersensuous world grows and grows big with the invisible present, and big also with the past and the future, crowded with the ghosts of the dead and shadowed with oracles and portents. It is this supersensuous, supernatural world which is the eternity, the other-world, of primitive religion, not an endlessness of time, but a state removed from full sensuous reality, a world in which anything and everything may happen, a world peopled by demonic ancestors and liable to a splendid vagueness, to a "once upon a time-ness" denied to the present. It not unfrequently happens that people who know that the world nowadays obeys fixed laws have no difficulty in believing that six thousand years ago man was made direct from a lump of clay, and woman was made from one of man's superfluous ribs. The fashioning of the supersensuous world comes out very clearly in primitive man's views about the soul and life after death. Herbert Spencer noted long ago the influence of dreams in forming a belief in immortality, but being very rational himself, he extended to primitive man a quite alien quality of rationality. Herbert Spencer argued that when a savage has a dream he seeks to account for it, and in so doing invents a spirit world. The mistake here lies in the "seeks to account for it." (Primitive man, as Dr Beck observes, is not impelled by an Erkenntnisstrieb. Dr Beck says he has counted upwards of 30 of these mythological Triebe (tendencies) with which primitive man has been endowed.) Man is at first too busy LIVING to have any time for disinterested THINKING. He dreams a dream and it is real for him. He does not seek to account for it any more than for his hands and feet. He cannot distinguish between a CONception and a PERception, that is all. He remembers his ancestors or they appear to him in a dream; therefore they are alive still, but only as a rule to about the third generation. Then he remembers them no more and they cease to be. Next as regards his own soul. He feels something within him, his life-power, his will to live, his power to act, his personality--whatever we like to call it. He cannot touch this thing that is himself, but it is real. His friend too is alive and one day he is dead; he cannot move, he cannot act. Well, something has gone that was his friend's self. He has stopped breathing. Was it his breath? or he is bleeding; is it his blood? This life-power IS something; does it live in his heart or his lungs or his midriff? He did not see it go; perhaps it is like wind, an anima, a Geist, a ghost. But again it comes back in a dream, only looking shadowy; it is not the man's life, it is a thin copy of the man; it is an "image" (eidolon). It is like that shifting distorted thing that dogs the living man's footsteps in the sunshine; it is a "shade" (skia). (The two conceptions of the soul, as a life-essence, inseparable from the body, and as a separable phantom seem to occur in most primitive systems. They are distinct conceptions but are inextricably blended in savage thought. The two notions Korperseele and Psyche have been very fully discussed in Wundt's "Volkerpsychologie" II. pages 1-142, Leipzig, 1900.) Ghosts and sprites, ancestor worship, the soul, oracles, prophecy; all these elements of the primitive supersensuous world we willingly admit to be the proper material of religion; but other elements are more surprising; such are class-names, abstract ideas, numbers, geometrical figures. We do not nowadays think of these as of religious content, but to primitive men they were all part of the furniture of his supernatural world. With respect to class-names, Dr Tylor ("Primitive Culture", Vol. II. page 245 (4th edition), 1903.) has shown how instructive are the first attempts of the savage to get at the idea of a class. Things in which similarity is observed, things indeed which can be related at all are to the savage KINDRED. A species is a family or a number of individuals with a common god to look after them. Such for example is the Finn doctrine of the haltia. Every object has its haltia, but the haltiat were not tied to the individual, they interested themselves in every member of the species. Each stone had its haltia, but that haltia was interested in other stones; the individuals disappeared, the haltia remained. Nor was it only class-names that belonged to the supersensuous world. A man's own proper-name is a sort of spiritual essence of him, a kind of soul to be carefully concealed. By pronouncing a name you bring the thing itself into being. When Elohim would create Day "he called out to the Light 'Day,' and to the Darkness he called out 'Night'"; the great magician pronounced the magic Names and the Things came into being. "In the beginning was the Word" is literally true, and this reflects the fact that our CONCEPTUAL world comes into being by the mental process of naming. (For a full discussion of this point see Beck, "Nachahmung" page 41, "Die Sprache".) In old times people went further; they thought that by naming events they could bring them to be, and custom even to-day keeps up the inveterate magical habit of wishing people "Good Morning" and a "Happy Christmas." Number, too, is part of the supersensuous world that is thoroughly religious. We can see and touch seven apples, but seven itself, that wonderful thing that shifts from object to object, giving it its SEVENness, that living thing, for it begets itself anew in multiplication--surely seven is a fit denizen of the upper-world. Originally all numbers dwelt there, and a certain supersensuous sanctity still clings to seven and three. We still say "Holy, Holy, Holy," and in some mystic way feel the holier. The soul and the supersensuous world get thinner and thinner, rarer and more rarified, but they always trail behind them clouds of smoke and vapour from the world of sense and space whence they have come. It is difficult for us even nowadays to use the word "soul" without lapsing into a sensuous mythology. The Cartesians' sharp distinction between res extensa non cogitans and res cogitans non extansa is remote. So far then man, through the processes of his thinking, has provided himself with a supersensuous world, the world of sense-delusion, of smoke and cloud, of dream and phantom, of imagination, of name and number and image. The natural course would now seem to be that this supersensuous world should develop into the religious world as we know it, that out of a vague animism with ghosts of ancestors, demons, and the like, there should develop in due order momentary gods (Augenblicks-Gotter), tribal gods, polytheism, and finally a pure monotheism. This course of development is usually assumed, but it is not I think quite what really happens. The supersensuous world as we have got it so far is too theoretic to be complete material of religion. It is indeed only one factor, or rather it is as it were a lifeless body that waits for a living spirit to possess and inform it. Had the theoretic factor remained uninformed it would eventually have separated off into its constituent elements of error and truth, the error dying down as a belated metaphysic, the truth developing into a correct and scientific psychology of the subjective. But man has ritual as well as mythology; that is, he feels and acts as well as thinks; nay more he probably feels and acts long before he definitely thinks. This contradicts all our preconceived notions of theology. Man, we imagine, believes in a god or gods and then worships. The real order seems to be that, in a sense presently to be explained, he worships, he feels and acts, and out of his feeling and action, projected into his confused thinking, he develops a god. We pass therefore to our second factor in religion:--ritual. The word "ritual" brings to our modern minds the notion of a church with a priesthood and organised services. Instinctively we think of a congregation meeting to confess sins, to receive absolution, to pray, to praise, to listen to sermons, and possibly to partake of sacraments. Were we to examine these fully developed phenomena we should hardly get further in the analysis of our religious conceptions than the notion of a highly anthropomorphic god approached by purely human methods of personal entreaty and adulation. Further, when we first come to the study of primitive religions we expect a priori to find the same elements, though in a ruder form. We expect to see "The heathen in his blindness bow down to wood and stone," but the facts that actually confront us are startlingly dissimilar. Bowing down to wood and stone is an occupation that exists mainly in the minds of hymn-writers. The real savage is more actively engaged. Instead of asking a god to do what he wants done, he does it or tries to do it himself; instead of prayers he utters spells. In a word he is busy practising magic, and above all he is strenuously engaged in dancing magical dances. When the savage wants rain or wind or sunshine, he does not go to church; he summons his tribe and they dance a rain-dance or wind-dance or sun-dance. When a savage goes to war we must not picture his wife on her knees at home praying for the absent; instead we must picture her dancing the whole night long; not for mere joy of heart or to pass the weary hours; she is dancing his war-dance to bring him victory. Magic is nowadays condemned alike by science and by religion; it is both useless and impious. It is obsolete, and only practised by malign sorcerers in obscure holes and corners. Undoubtedly magic is neither religion nor science, but in all probability it is the spiritual protoplasm from which religion and science ultimately differentiated. As such the doctrine of evolution bids us scan it closely. Magic may be malign and private; nowadays it is apt to be both. But in early days magic was as much for good as for evil; it was publicly practised for the common weal. The gist of magic comes out most clearly in magical dances. We think of dancing as a light form of recreation, practised by the young from sheer joie de vivre and unsuitable for the mature. But among the Tarahumares (Carl Lumholtz, "Unknown Mexico", page 330, London, 1903.) in Mexico the word for dancing, nolavoa, means "to work." Old men will reproach young men saying "Why do you not go to work?" meaning why do you not dance instead of only looking on. The chief religious sin of which the Tarahumare is conscious is that he has not danced enough and not made enough tesvino, his cereal intoxicant. Dancing then is to the savage WORKING, DOING, and the dance is in its origin an imitation or perhaps rather an intensification of processes of work. (Karl Bucher, "Arbeit und Rhythmus", Leipzig (3rd edition), 1902, passim.) Repetition, regular and frequent, constitutes rhythm and rhythm heightens the sense of will power in action. Rhythmical action may even, as seen in the dances of Dervishes, produce a condition of ecstasy. Ecstasy among primitive peoples is a condition much valued; it is often, though not always, enhanced by the use of intoxicants. Psychologically the savage starts from the sense of his own will power, he stimulates it by every means at his command. Feeling his will strongly and knowing nothing of natural law he recognises no limits to his own power; he feels himself a magician, a god; he does not pray, he WILLS. Moreover he wills collectively (The subject of collective hallucination as an element in magic has been fully worked out by MM. Hubert and Mauss. "Theorie generale de la Magie", In "L'Annee Sociologique", 1902--3, page 140.), reinforced by the will and action of his whole tribe. Truly of him it may be said "La vie deborde l'intelligence, l'intelligence c'est un retrecissement." (Henri Bergson, "L'Evolution Creatrice", page 50.) The magical extension and heightening of personality come out very clearly in what are rather unfortunately known as MIMETIC dances. Animal dances occur very frequently among primitive peoples. The dancers dress up as birds, beasts, or fishes, and reproduce the characteristic movements and habits of the animals impersonated. (So characteristic is this impersonation in magical dancing that among the Mexicans the word for magic, navali, means "disguise." K. Th. Preuss, "Archiv f. Religionswissenschaft", 1906, page 97.) A very common animal dance is the frog-dance. When it rains the frogs croak. If you desire rain you dress up like a frog and croak and jump. We think of such a performance as a conscious imitation. The man, we think, is more or less LIKE a frog. That is not how primitive man thinks; indeed, he scarcely thinks at all; what HE wants done the frog can do by croaking and jumping, so he croaks and jumps and, for all he can, BECOMES a frog. "L'intelligence animale JOUE sans doute les representations plutot qu'elle ne les pense." (Bergson, "L'Evolution Creatrice", page 205.) We shall best understand this primitive state of mind if we study the child "born in sin." If a child is "playing at lions" he does not IMITATE a lion, i.e. he does not consciously try to be a thing more or less like a lion, he BECOMES one. His reaction, his terror, is the same as if the real lion were there. It is this childlike power of utter impersonation, of BEING the thing we act or even see acted, this extension and intensification of our own personality that lives deep down in all of us and is the very seat and secret of our joy in the drama. A child's mind is indeed throughout the best clue to the understanding of savage magic. A young and vital child knows no limit to his own will, and it is the only reality to him. It is not that he wants at the outset to fight other wills, but that they simply do not exist for him. Like the artist he goes forth to the work of creation, gloriously alone. His attitude towards other recalcitrant wills is "they simply must." Let even a grown man be intoxicated, be in love, or subject to an intense excitement, the limitations of personality again fall away. Like the omnipotent child he is again a god, and to him all things are possible. Only when he is old and weary does he cease to command fate. The Iroquois (Hewitt, "American Anthropologist", IV. I. page 32, 1902, N.S.) of North America have a word, orenda, the meaning of which is easier to describe than to define, but it seems to express the very soul of magic. This orenda is your power to do things, your force, sometimes almost your personality. A man who hunts well has much and good orenda; the shy bird who escapes his snares has a fine orenda. The orenda of the rabbit controls the snow and fixes the depth to which it will fall. When a storm is brewing the magician is said to be making its orenda. When you yourself are in a rage, great is your orenda. The notes of birds are utterances of their orenda. When the maize is ripening, the Iroquois know it is the sun's heat that ripens it, but they know more; it is the cigala makes the sun to shine and he does it by chirping, by uttering his orenda. This orenda is sometimes very like the Greek thumos, your bodily life, your vigour, your passion, your power, the virtue that is in you to feel and do. This notion of orenda, a sort of pan-vitalism, is more fluid than animism, and probably precedes it. It is the projection of man's inner experience, vague and unanalysed, into the outer world. The mana of the Melanesians (Codrington, "The Melanesians", pages 118, 119, 192, Oxford, 1891.) is somewhat more specialised--all men do not possess mana--but substantially it is the same idea. Mana is not only a force, it is also an action, a quality, a state, at once a substantive, an adjective, and a verb. It is very closely neighboured by the idea of sanctity. Things that have mana are tabu. Like orenda it manifests itself in noises, but specially mysterious ones, it is mana that is rustling in the trees. Mana is highly contagious, it can pass from a holy stone to a man or even to his shadow if it cross the stone. "All Melanesian religion," Dr Codrington says, "consists in getting mana for oneself or getting it used for one's benefit." (Codrington, "The Melanesians", page 120, Oxford, 1891.) Specially instructive is a word in use among the Omaka (See Prof. Haddon, "Magic and Fetishism", page 60, London, 1906. Dr Vierkandt ("Globus", July, 1907, page 41) thinks that "Fernzauber" is a later development from Nahzauber.), wazhin-dhedhe, "directive energy, to send." This word means roughly what we should call telepathy, sending out your thought or will-power to influence another and affect his action. Here we seem to get light on what has always been a puzzle, the belief in magic exercised at a distance. For the savage will, distance is practically non-existent, his intense desire feels itself as non-spatial. (This notion of mana, orenda, wazhin-dhedhe and the like lives on among civilised peoples in such words as the Vedic brahman in the neuter, familiar to us in its masculine form Brahman. The neuter, brahman, means magic power of a rite, a rite itself, formula, charm, also first principle, essence of the universe. It is own cousin to the Greek dunamis and phusis. See MM. Hubert et Mauss, "Theorie generale de la Magie", page 117, in "L'Annee Sociologique", VII.) Through the examination of primitive ritual we have at last got at one tangible, substantial factor in religion, a real live experience, the sense, that is, of will, desire, power actually experienced in person by the individual, and by him projected, extended into the rest of the world. At this stage it may fairly be asked, though the question cannot with any certainty be answered, "at what point in the evolution of man does this religious experience come in?" So long as an organism reacts immediately to outside stimulus, with a certainty and conformity that is almost chemical, there is, it would seem, no place, no possibility for magical experience. But when the germ appears of an intellect that can foresee an end not immediately realised, or rather when a desire arises that we feel and recognise as not satisfied, then comes in the sense of will and the impulse magically to intensify that will. The animal it would seem is preserved by instinct from drawing into his horizon things which do not immediately subserve the conservation of his species. But the moment man's life-power began to make on the outside world demands not immediately and inevitably realised in action (I owe this observation to Dr K. Th. Preuss. He writes ("Archiv f. Relig." 1906, page 98), "Die Betonung des Willens in den Zauberakten ist der richtige Kern. In der Tat muss der Mensch den Willen haben, sich selbst und seiner Umgebung besondere Fahigkeiten zuzuschreiben, und den Willen hat er, sobald sein Verstand ihn befahigt, EINE UBER DEN INSTINKT HINAUSGEHEN DER FURSORGE fur sich zu zeigen. SO LANGE IHN DER INSTINKT ALLEIN LEITET, KONNEN ZAUBERHANDLUNGEN NICHT ENSTEHEN." For more detailed analysis of the origin of magic, see Dr Preuss "Ursprung der Religion und Kunst", "Globus", LXXXVI. and LXXXVII.), then a door was opened to magic, and in the train of magic followed errors innumerable, but also religion, philosophy, science and art. The world of mana, orenda, brahman is a world of feeling, desiring, willing, acting. What element of thinking there may be in it is not yet differentiated out. But we have already seen that a supersensuous world of thought grew up very early in answer to other needs, a world of sense-illusions, shadows, dreams, souls, ghosts, ancestors, names, numbers, images, a world only wanting as it were the impulse of mana to live as a religion. Which of the two worlds, the world of thinking or the world of doing, developed first it is probably idle to inquire. (If external stimuli leave on organisms a trace or record such as is known as an Engram, this physical basis of memory and hence of thought is almost coincident with reaction of the most elementary kind. See Mr Francis Darwin's Presidential Address to the British Association, Dublin, 1908, page 8, and again Bergson places memory at the very root of conscious existence, see "L'Evolution Creatrice", page 18, "le fond meme de notre existence consciente est memoire, c'est a dire prolongation du passee dans le present," and again "la duree mord dans le temps et y laisse l'enpreint de son dent," and again, "l'Evolution implique une continuation reelle du passee par le present.") It is more important to ask, Why do these two worlds join? Because, it would seem, mana, the egomaniac or megalomaniac element, cannot get satisfied with real things, and therefore goes eagerly out to a false world, the supersensuous other-world whose growth we have sketched. This junction of the two is fact, not fancy. Among all primitive peoples dead men, ghosts, spirits of all kinds, become the chosen vehicle of mana. Even to this day it is sometimes urged that religion, i.e. belief in the immortality of the soul, is true "because it satisfies the deepest craving of human nature." The two worlds, of mana and magic on the one hand, of ghosts and other-world on the other, combine so easily because they have the same laws, or rather the same comparative absence of law. As in the world of dreams and ghosts, so in the world of mana, space and time offer no obstacles; with magic all things are possible. In the one world what you imagine is real; in the other what you desire is ipso facto accomplished. Both worlds are egocentric, megalomaniac, filled to the full with unbridled human will and desire. We are all of us born in sin, in that sin which is to science "the seventh and deadliest," anthropomorphism, we are egocentric, ego-projective. Hence necessarily we make our gods in our own image. Anthropomorphism is often spoken of in books on religion and mythology as if it were a last climax, a splendid final achievement in religious thought. First, we are told, we have the lifeless object as god (fetichism), then the plant or animal (phytomorphism, theriomorphism), and last God is incarnate in the human form divine. This way of putting things is misleading. Anthropomorphism lies at the very beginning of our consciousness. Man's first achievement in thought is to realise that there is anything at all not himself, any object to his subject. When he has achieved however dimly this distinction, still for long, for very long he can only think of those other things in terms of himself; plants and animals are people with ways of their own, stronger or weaker than himself but to all intents and purposes human. Again the child helps us to understand our own primitive selves. To children animals are always people. You promise to take a child for a drive. The child comes up beaming with a furry bear in her arms. You say the bear cannot go. The child bursts into tears. You think it is because the child cannot endure to be separated from a toy. It is no such thing. It is the intolerable hurt done to the bear's human heart--a hurt not to be healed by any proffer of buns. He wanted to go, but he was a shy, proud bear, and he would not say so. The relation of magic to religion has been much disputed. According to one school religion develops out of magic, according to another, though they ultimately blend, they are at the outset diametrically opposed, magic being a sort of rudimentary and mistaken science (This view held by Dr Frazer is fully set forth in his "Golden Bough" (2nd edition), pages 73-79, London, 1900. It is criticised by Mr R.R. Marett in "From Spell to Prayer", "Folk-Lore" XI. 1900, page 132, also very fully by MM. Hubert and Mauss, "Theorie generale de la Magie", in "L'Annee Sociologique", VII. page 1, with Mr Marett's view and with that of MM. Hubert and Mauss I am in substantial agreement.), religion having to do from the outset with spirits. But, setting controversy aside, at the present stage of our inquiry their relation becomes, I think, fairly clear. Magic is, if my view (This view as explained above is, I believe, my own most serious contribution to the subject. In thinking it out I was much helped by Prof. Gilbert Murray.) be correct, the active element which informs a supersensuous world fashioned to meet other needs. This blend of theory and practice it is convenient to call religion. In practice the transition from magic to religion, from Spell to Prayer, has always been found easy. So long as mana remains impersonal you order it about; when it is personified and bulks to the shape of an overgrown man, you drop the imperative and cringe before it. "My will be done" is magic, "Thy Will be done" is the last word in religion. The moral discipline involved in the second is momentous, the intellectual advance not striking. I have spoken of magical ritual as though it were the informing life-spirit without which religion was left as an empty shell. Yet the word ritual does not, as normally used, convey to our minds this notion of intense vitalism. Rather we associate ritual with something cut and dried, a matter of prescribed form and monotonous repetition. The association is correct; ritual tends to become less and less informed by the life-impulse, more and more externalised. Dr Beck ("Die Nachahmung und ihre Bedeutung fur Psychologie und Volkerkunde", Leipzig, 1904.) in his brilliant monograph on "Imitation" has laid stress on the almost boundless influence of the imitation of one man by another in the evolution of civilisation. Imitation is one of the chief spurs to action. Imitation begets custom, custom begets sanctity. At first all custom is sacred. To the savage it is as much a religious duty to tattoo himself as to sacrifice to his gods. But certain customs naturally survive, because they are really useful; they actually have good effects, and so need no social sanction. Others are really useless; but man is too conservative and imitative to abandon them. These become ritual. Custom is cautious, but la vie est aleatoire. (Bergson, op. cit. page 143.) Dr Beck's remarks on ritual are I think profoundly true and suggestive, but with this reservation--they are true of ritual only when uninformed by personal experience. The very elements in ritual on which Dr Beck lays such stress, imitation, repetition, uniformity and social collectivity, have been found by the experience of all time to have a twofold influence--they inhibit the intellect, they stimulate and suggest emotion, ecstasy, trance. The Church of Rome knows what she is about when she prescribes the telling of the rosary. Mystery-cults and sacraments, the lineal descendants of magic, all contain rites charged with suggestion, with symbols, with gestures, with half-understood formularies, with all the apparatus of appeal to emotion and will--the more unintelligible they are the better they serve their purpose of inhibiting thought. Thus ritual deadens the intellect and stimulates will, desire, emotion. "Les operations magiques... sont le resultat d'une science et d'une habitude qui exaltent la volonte humaine au-dessus de ses limites habituelles." (Eliphas Levi, "Dogme et Rituel de la haute Magie", II. page 32, Paris, 1861, and "A defence of Magic", by Evelyn Underhill, "Fortnightly Review", 1907.) It is this personal EXPERIENCE, this exaltation, this sense of immediate, non-intellectual revelation, of mystical oneness with all things, that again and again rehabilitates a ritual otherwise moribund. To resume. The outcome of our examination of ORIGINES seems to be that religious phenomena result from two delusive processes--a delusion of the non-critical intellect, a delusion of the over-confident will. Is religion then entirely a delusion? I think not. (I am deeply conscious that what I say here is a merely personal opinion or sentiment, unsupported and perhaps unsupportable by reason, and very possibly quite worthless, but for fear of misunderstanding I prefer to state it.) Every dogma religion has hitherto produced is probably false, but for all that the religious or mystical spirit may be the only way of apprehending some things and these of enormous importance. It may also be that the contents of this mystical apprehension cannot be put into language without being falsified and misstated, that they have rather to be felt and lived than uttered and intellectually analysed, and thus do not properly fall under the category of true or false, in the sense in which these words are applied to propositions; yet they may be something for which "true" is our nearest existing word and are often, if not necessary at least highly advantageous to life. That is why man through a series of more or less grossly anthropomorphic mythologies and theologies with their concomitant rituals tries to restate them. Meantime we need not despair. Serious psychology is yet young and has only just joined hands with physiology. Religious students are still hampered by mediaevalisms such as Body and Soul, and by the perhaps scarcely less mythological segregations of Intellect, Emotion, Will. But new facts (See the "Proceedings" of the Society for Psychical Research, London, passim, and especially Vols. VII.-XV. For a valuable collection of the phenomena of mysticism, see William James, "Varieties of Religious Experience", Edinburgh, 1901-2.) are accumulating, facts about the formation and flux of personality, and the relations between the conscious and the sub-conscious. Any moment some great imagination may leap out into the dark, touch the secret places of life, lay bare the cardinal mystery of the marriage of the spatial with the non-spatial. It is, I venture to think, towards the apprehension of such mysteries, not by reason only, but by man's whole personality, that the religious spirit in the course of its evolution through ancient magic and modern mysticism is ever blindly yet persistently moving. Be this as it may, it is by thinking of religion in the light of evolution, not as a revelation given, not as a realite faite but as a process, and it is so only, I think, that we attain to a spirit of real patience and tolerance. We have ourselves perhaps learnt laboriously something of the working of natural law, something of the limitations of our human will, and we have therefore renounced the practice of magic. Yet we are bidden by those in high places to pray "Sanctify this water to the mystical washing away of sin." Mystical in this connection spells magical, and we have no place for a god-magician: the prayer is to us unmeaning, irreverent. Or again, after much toil we have ceased, or hope we have ceased, to think anthropomorphically. Yet we are invited to offer formal thanks to God for a meal of flesh whose sanctity is the last survival of that sacrifice of bulls and goats he has renounced. Such a ritual confuses our intellect and fails to stir our emotion. But to others this ritual, magical or anthropomorphic as it is, is charged with emotional impulse, and others, a still larger number, think that they act by reason when really they are hypnotised by suggestion and tradition; their fathers did this or that and at all costs they must do it. It was good that primitive man in his youth should bear the yoke of conservative custom; from each man's neck that yoke will fall, when and because he has outgrown it. Science teaches us to await that moment with her own inward and abiding patience. Such a patience, such a gentleness we may well seek to practise in the spirit and in the memory of Darwin. XXVI. EVOLUTION AND THE SCIENCE OF LANGUAGE. By P. Giles, M.A., LL.D. (Aberdeen), Reader in Comparative Philology in the University of Cambridge. In no study has the historical method had a more salutary influence than in the Science of Language. Even the earliest records show that the meaning of the names of persons, places, and common objects was then, as it has always been since, a matter of interest to mankind. And in every age the common man has regarded himself as competent without special training to explain by inspection (if one may use a mathematical phrase) the meaning of any words that attracted his attention. Out of this amateur etymologising has sprung a great amount of false history, a kind of historical mythology invented to explain familiar names. A single example will illustrate the tendency. According to the local legend the ancestor of the Earl of Erroll--a husbandman who stayed the flight of his countrymen in the battle of Luncarty and won the victory over the Danes by the help of the yoke of his oxen--exhausted with the fray uttered the exclamation "Hoch heigh!" The grateful king about to ennoble the victorious ploughman at once replied: "Hoch heigh! said ye And Hay shall ye be." The Norman origin of the name Hay is well-known, and the battle of Luncarty long preceded the appearance of Normans in Scotland, but the legend nevertheless persists. Though the earliest European treatise on philological questions which is now extant--the "Cratylus" of Plato,--as might be expected from its authorship, contains some acute thinking and some shrewd guesses, yet the work as a whole is infantine in its handling of language, and it has been doubted whether Plato was more than half serious in some of the suggestions which he puts forward. (For an account of the "Cratylus" with references to other literature see Sandys' "History of Classical Scholarship", I. page 92 ff., Cambridge, 1903.) In the hands of the Romans things were worse even than they had been in the hands of Plato and his Greek successors. The lack of success on the part of Varro and later Roman writers may have been partly due to the fact that, from the etymological point of view, Latin is a much more difficult language than Greek; it is by no means so closely connected with Greek as the ancients imagined, and they had no knowledge of the Celtic languages from which, on some sides at least, much greater light on the history of the Latin language might have been obtained. Roman civilisation was a late development compared with Greek, and its records dating earlier than 300 B.C.--a period when the best of Greek literature was already in existence--are very few and scanty. Varro it is true was much more of an antiquary than Plato, but his extant works seem to show that he was rather a "dungeon of learning" than an original thinker. A scientific knowledge of language can be obtained only by comparison of different languages of the same family and the contrasting of their characteristics with those of another family or other families. It never occurred to the Greeks that any foreign language was worthy of serious study. Herodotus and other travellers and antiquaries indeed picked up individual words from various languages, either as being necessary in communication with the inhabitants of the countries where they sojourned, or because of some point which interested them personally. Plato and others noticed the similarity of some Phrygian words to Greek, but no systematic comparison seems ever to have been instituted. In the Middle Ages the treatment of language was in a sense more historical. The Middle Ages started with the hypothesis, derived from the book of Genesis, that in the early world all men were of one language and of one speech. Though on the same authority they believed that the plain of Shinar has seen that confusion of tongues whence sprang all the languages upon earth, they seem to have considered that the words of each separate language were nevertheless derived from this original tongue. And as Hebrew was the language of the Chosen People, it was naturally assumed that this original tongue was Hebrew. Hence we find Dante declaring in his treatise on the Vulgar Tongue (Dante "de Vulgari Eloquio", I. 4.) that the first word man uttered in Paradise must have been "El," the Hebrew name of his Maker, while as a result of the fall of Adam, the first utterance of every child now born into this world of sin and misery is "heu," Alas! After the splendidly engraved bronze plates containing, as we now know, ritual regulations for certain cults, were discovered in 1444 at the town of Gubbio, in Umbria, they were declared, by some authorities, to be written in excellent Hebrew. The study of them has been the fascination and the despair of many a philologist. Thanks to the devoted labours of numerous scholars, mainly in the last sixty years, the general drift of these inscriptions is now known. They are the only important records of the ancient Umbrian language, which was related closely to that of the Samnites and, though not so closely, to that of the Romans on the other side of the Apennines. Yet less than twenty years ago a book was published in Germany, which boasts itself the home of Comparative Philology, wherein the German origin of the Umbrian language was no less solemnly demonstrated than had been its Celtic origin by Sir William Betham in 1842. It is good that the study of language should be historical, but the first requisite is that the history should be sound. How little had been learnt of the true history of language a century ago may be seen from a little book by Stephen Weston first published in 1802 and several times reprinted, where accidental assonance is considered sufficient to establish connection. Is there not a word "bad" in English and a word "bad" in Persian which mean the same thing? Clearly therefore Persian and English must be connected. The conclusion is true, but it is drawn from erroneous premises. As stated, this identity has no more value than the similar assonance between the English "cover" and the Hebrew "kophar", where the history of "cover" as coming through French from a Latin "co-operire" was even in 1802 well-known to many. To this day, in spite of recent elaborate attempts (Most recently in H. Moller's "Semitisch und Indogermanisch", Erster Teil, Kopenhagen, 1907.) to establish connection between the Indo-Germanic and the Semitic families of languages, there is no satisfactory evidence of such relation between these families. This is not to deny the possibility of such a connection at a very early period; it is merely to say that through the lapse of long ages all trustworthy record of such relationship, if it ever existed, has been, so far as present knowledge extends, obliterated. But while Stephen Weston was publishing, with much public approval, his collection of amusing similarities between languages--similarities which proved nothing--the key to the historical study of at least one family of languages had already been found by a learned Englishman in a distant land. In 1783 Sir William Jones had been sent out as a judge in the supreme court of judicature in Bengal. While still a young man at Oxford he was noted as a linguist; his reputation as a Persian scholar had preceded him to the East. In the intervals of his professional duties he made a careful study of the language which was held sacred by the natives of the country in which he was living. He was mainly instrumental in establishing a society for the investigation of language and related subjects. He was himself the first president of the society, and in the "third anniversary discourse" delivered on February 2, 1786, he made the following observations: "The Sanscrit language, whatever be its antiquity, is of a wonderful structure; more perfect than the GREEK, more copious than the LATIN, and more exquisitely refined than either, yet bearing to both of them a stronger affinity, both in the roots of verbs and in the forms of grammar, than could possibly have been produced by accident; so strong indeed, that no philologer could examine them all three, without believing them to have sprung from some common source, which, perhaps, no longer exists: there is a similar reason, though not quite so forcible, for supposing that both the Gothick and the Celtick, though blended with a very different idiom, had the same origin with the Sanscrit; and the old Persian might be added to the same family, if this was the place for discussing any question concerning the antiquities of Persia." ("Asiatic Researches", I. page 422, "Works of Sir W. Jones", I. page 26, London, 1799.) No such epoch-making discovery was probably ever announced with less flourish of trumpets. Though Sir William Jones lived for eight years more and delivered other anniversary discourses, he added nothing of importance to this utterance. He had neither the time nor the health that was needed for the prosecution of so arduous an undertaking. But the good seed did not fall upon stony ground. The news was speedily conveyed to Europe. By a happy chance, the sudden renewal of war between France and England in 1803 gave Friedrich Schlegel the opportunity of learning Sanscrit from Alexander Hamilton, an Englishman who, like many others, was confined in Paris during the long struggle with Napoleon. The influence of Schlegel was not altogether for good in the history of this research, but he was inspiring. Not upon him but upon Franz Bopp, a struggling German student who spent some time in Paris and London a dozen years later, fell the mantle of Sir William Jones. In Bopp's Comparative Grammar of the Indo-Germanic languages which appeared in 1833, three-quarters of a century ago, the foundations of Comparative Philology were laid. Since that day the literature of the subject has grown till it is almost, if not altogether, beyond the power of any single man to cope with it. But long as the discourse may be, it is but the elaboration of the text that Sir William Jones supplied. With the publication of Bopp's Comparative Grammar the historical study of language was put upon a stable footing. Needless to say much remained to be done, much still remains to be done. More than once there has been danger of the study following erroneous paths. Its terminology and its point of view have in some degree changed. But nothing can shake the truth of the statement that the Indo-Germanic languages constitute in themselves a family sprung from the same source, marked by the same characteristics, and differentiated from all other languages by formation, by vocabulary, and by syntax. The historical method was applied to language long before it reached biology. Nearly a quarter of a century before Charles Darwin was born, Sir William Jones had made the first suggestion of a comparative study of languages. Bopp's Comparative Grammar began to be published nine years before the first draft of Darwin's treatise on the Origin of Species was put on paper in 1842. It is not therefore on the history of Comparative Philology in general that the ideas of Darwin have had most influence. Unfortunately, as Jowett has said in the introduction to his translation of Plato's "Republic", most men live in a corner. The specialisation of knowledge has many advantages, but it has also disadvantages, none worse perhaps than that it tends to narrow the specialist's horizon and to make it more difficult for one worker to follow the advances that are being made by workers in other departments. No longer is it possible as in earlier days for an intellectual prophet to survey from a Pisgah height all the Promised Land. And the case of linguistic research has been specially hard. This study has, if the metaphor may be allowed, a very extended frontier. On one side it touches the domain of literature, on other sides it is conterminous with history, with ethnology and anthropology, with physiology in so far as language is the production of the brain and tissues of a living being, with physics in questions of pitch and stress accent, with mental science in so far as the principles of similarity, contrast, and contiguity affect the forms and the meanings of words through association of ideas. The territory of linguistic study is immense, and it has much to supply which might be useful to the neighbours who border on that territory. But they have not regarded her even with that interest which is called benevolent because it is not actively maleficent. As Horne Tooke remarked a century ago, Locke had found a whole philosophy in language. What have the philosophers done for language since? The disciples of Kant and of Wilhelm von Humboldt supplied her plentifully with the sour grapes of metaphysics; otherwise her neighbours have left her severely alone save for an occasional "Ausflug," on which it was clear they had sadly lost their bearings. Some articles in Psychological Journals, Wundt's great work on "Volkerpsychologie" (Erster Band: "Die Sprache", Leipzig, 1900. New edition, 1904. This work has been fertile in producing both opponents and supporters. Delbruck, "Grundfragen der Sprachforschung", Strassburg, 1901, with a rejoinder by Wundt, "Sprachgeschichte" and "Sprachpsychologie", Leipzig, 1901; L. Sutterlin, "Das Wesen der Sprachgebilde", Heidelberg, 1902; von Rozwadowski, "Wortbildung und Wortbedeutung", Heidelberg, 1904; O. Dittrich, "Grundzuge der Sprachpsychologie", Halle, 1904, Ch. A. Sechehaye, "Programme et methodes de la linguistique theorique", Paris, 1908.), and Mauthner's brilliantly written "Beitrage zu einer Kritik der Sprache" (In three parts: (i) "Sprache und Psychologie, (ii) "Zur Sprachwissenschaft", both Stuttgart 1901, (iii) "Zur Grammatic und Logik" (with index to all three volumes), Stuttgart and Berlin, 1902.) give some reason to hope that, on one side at least, the future may be better than the past. Where Charles Darwin's special studies came in contact with the Science of Language was over the problem of the origin and development of language. It is curious to observe that, where so many fields of linguistic research have still to be reclaimed--many as yet can hardly be said to be mapped out,--the least accessible field of all--that of the Origin of Language--has never wanted assiduous tillers. Unfortunately it is a field beyond most others where it may be said that "Wilding oats and luckless darnel grow." If Comparative Philology is to work to purpose here, it must be on results derived from careful study of individual languages and groups of languages. But as yet the group which Sir William Jones first mapped out and which Bopp organised is the only one where much has been achieved. Investigation of the Semitic group, in some respects of no less moment in the history of civilisation and religion, where perhaps the labour of comparison is not so difficult, as the languages differ less among themselves, has for some reason strangely lagged behind. Some years ago in the "American Journal of Philology" Paul Haupt pointed out that if advance was to be made, it must be made according to the principles which had guided the investigation of the Indo-Germanic languages to success, and at last a Comparative Grammar of an elaborate kind is in progress also for the Semitic languages. (Brockelmann, "Vergleichende Grammatik der semitischen Sprachen", Berlin, 1907 ff. Brockelmann and Zimmern had earlier produced two small hand-books. The only large work was William Wright's "Lectures on the Comparative Grammar of the Semitic Languages", Cambridge, 1890.) For the great group which includes Finnish, Hungarian, Turkish and many languages of northern Asia, a beginning, but only a beginning has been made. It may be presumed from the great discoveries which are in progress in Turkestan that presently much more will be achieved in this field. But for a certain utterance to be given by Comparative Philology on the question of the origin of language it is necessary that not merely for these languages but also for those in other quarters of the globe, the facts should be collected, sifted and tabulated. England rules an empire which contains a greater variety of languages by far than were ever held under one sway before. The Government of India is engaged in producing, under the editorship of Dr Grierson, a linguistic survey of India, a remarkable undertaking and, so far as it has gone, a remarkable achievement. Is it too much to ask that, with the support of the self-governing colonies, a similar survey should be undertaken for the whole of the British Empire? Notwithstanding the great number of books that have been written on the origin of language in the last three and twenty centuries, the results of the investigation which can be described as certain are very meagre. The question originally raised was whether language came into being thesei or phusei, by convention or by nature. The first alternative, in its baldest form at least, has passed from out the field of controversy. No one now claims that names were given to living things or objects or activities by formal agreement among the members of an early community, or that the first father of mankind passed in review every living thing and gave it its name. Even if the record of Adam's action were to be taken literally there would still remain the question, whence had he this power? Did he develop it himself or was it a miraculous gift with which he was endowed at his creation? If the latter, then as Wundt says ("Volkerpsychologie", I. 2, page 585.), "the miracle of language is subsumed in the miracle of creation." If Adam developed language of himself, we are carried over to the alternative origin of phusei. On this hypothesis we must assume that the natural growth which modern theories of development regard as the painful progress of multitudinous generations was contracted into the experience of a single individual. But even if the origin of language is admitted to be NATURAL there may still be much variety of signification attached to the word: NATURE, like most words which are used by philosophers, has accumulated many meanings, and as research into the natural world proceeds, is accumulating more. Forty years ago an animated controversy raged among the supporters of the theories which were named for short the bow-wow, the pooh-pooh and the ding-dong theories of the origin of language. The third, which was the least tenacious of life, was made known to the English-speaking world by the late Professor Max Muller who, however, when questioned, repudiated it as his own belief. ("Science of Thought", London, 1887, page 211.) It was taken by him from Heyse's lectures on language which were published posthumously by Steinthal. Put shortly the theory is that "everything which is struck, rings. Each substance has its peculiar ring. We can tell the more or less perfect structure of metals by their vibrations, by the answer which they give. Gold rings differently from tin, wood rings differently from stone; and different sounds are produced according to the nature of each percussion. It may be the same with man, the most highly organised of nature's work." (Max Muller as above, translating from Heyse.) Max Muller's repudiation of this theory was, however, not very whole-hearted for he proceeds later in the same argument: "Heyse's theory, which I neither adopted nor rejected, but which, as will be seen, is by no means incompatible with that which for many years has been gaining on me, and which of late has been so clearly formulated by Professor Noire, has been assailed with ridicule and torn to pieces, often by persons who did not even suspect how much truth was hidden behind its paradoxical appearance. We are still very far from being able to identify roots with nervous vibrations, but if it should appear hereafter that sensuous vibrations supply at least the raw material of roots, it is quite possible that the theory, proposed by Oken and Heyse, will retain its place in the history of the various attempts at solving the problem of the origin of language, when other theories, which in our own days were received with popular applause, will be completely forgotten." ("Science of Thought", page 212.) Like a good deal else that has been written on the origin of language, this statement perhaps is not likely to be altogether clear to the plain man, who may feel that even the "raw material of roots" is some distance removed from nervous vibrations, though obviously without the existence of afferent and efferent nerves articulate speech would be impossible. But Heyse's theory undoubtedly was that every thought or idea which occurred to the mind of man for the first time had its own special phonetic expression, and that this responsive faculty, when its object was thus fulfilled, became extinct. Apart from the philosophical question whether the mind acts without external stimulus, into which it is not necessary to enter here, it is clear that this theory can neither be proved nor disproved, because it postulates that this faculty existed only when language first began, and later altogether disappeared. As we have already seen, it is impossible for us to know what happened at the first beginnings of language, because we have no information from any period even approximately so remote; nor are we likely to attain it. Even in their earliest stages the great families of language which possess a history extending over many centuries--the Indo-Germanic and the Semitic--have very little in common. With the exception of Chinese, the languages which are apparently of a simpler or more primitive formation have either a history which, compared with that of the families mentioned, is very short, or, as in the case of the vast majority, have no history beyond the time extending only over a few years or, at most, a few centuries when they have been observed by competent scholars of European origin. But, if we may judge by the history of geology and other studies, it is well to be cautious in assuming for the first stages of development forces which do not operate in the later, unless we have direct evidence of their existence. It is unnecessary here to enter into a prolonged discussion of the other views christened by Max Muller, not without energetic protest from their supporters, the bow-wow and pooh-pooh theories of language. Suffice it to say that the former recognises as a source of language the imitation of the sounds made by animals, the fall of bodies into water or on to solid substances and the like, while the latter, also called the interjectional theory, looks to the natural ejaculations produced by particular forms of effort for the first beginnings of speech. It would be futile to deny that some words in most languages come from imitation, and that others, probably fewer in number, can be traced to ejaculations. But if either of these sources alone or both in combination gave rise to primitive speech, it clearly must have been a simple form of language and very limited in amount. There is no reason to think that it was otherwise. Presumably in its earliest stages language only indicated the most elementary ideas, demands for food or the gratification of other appetites, indications of danger, useful animals and plants. Some of these, such as animals or indications of danger, could often be easily represented by imitative sounds: the need for food and the like could be indicated by gesture and natural cries. Both sources are verae causae; to them Noire, supported by Max Muller, has added another which has sometimes been called the Yo-heave-ho theory. Noire contends that the real crux in the early stages of language is for primitive man to make other primitive men understand what he means. The vocal signs which commend themselves to one may not have occurred to another, and may therefore be unintelligible. It may be admitted that this difficulty exists, but it is not insuperable. The old story of the European in China who, sitting down to a meal and being doubtful what the meat in the dish might be, addressed an interrogative Quack-quack? to the waiter and was promptly answered by Bow-wow, illustrates a simple situation where mutual understanding was easy. But obviously many situations would be more complex than this, and to grapple with them Noire has introduced his theory of communal action. "It was common effort directed to a common object, it was the most primitive (uralteste) labour of our ancestors, from which sprang language and the life of reason." (Noire "Der Ursprung der Sprache", page 331, Mainz, 1877.) As illustrations of such common effort he cites battle cries, the rescue of a ship running on shore (a situation not likely to occur very early in the history of man), and others. Like Max Muller he holds that language is the utterance and the organ of thought for mankind, the one characteristic which separates man from the brute. "In common action the word was first produced; for long it was inseparably connected with action; through long-continued connection it gradually became the firm, intelligible symbol of action, and then in its development indicated also things of the external world in so far as the action affected them and finally the sound began to enter into a connexion with them also." (Op. cit. page 339.) In so far as this theory recognises language as a social institution it is undoubtedly correct. Darwin some years before Noire had pointed to the same social origin of language in the fourth chapter of his work on "The Expression of the Emotions in Man and Animals". "Naturalists have remarked, I believe with truth, that social animals, from habitually using their vocal organs as a means of intercommunication, use them on other occasions much more freely than other animals... The principle, also, of association, which is so widely extended in its power, has likewise played its part. Hence it allows that the voice, from having been employed as a serviceable aid under certain conditions, inducing pleasure, pain, rage, etc., is commonly used whenever the same sensations or emotions are excited, under quite different conditions, or in a lesser degree." ("The Expression of the Emotions", page 84 (Popular Edition, 1904). Darwin's own views on language which are set forth most fully in "The Descent of Man" (page 131 ff. (Popular Edition, 1906).) are characterised by great modesty and caution. He did not profess to be a philologist and the facts are naturally taken from the best known works of the day (1871). In the notes added to the second edition he remarks on Max Muller's denial of thought without words, "what a strange definition must here be given to the word thought!" (Op. cit. page 135, footnote 63.) He naturally finds the origin of language in "the imitation and modification of various natural sounds, the voices of other animals, and man's own instinctive cries aided by signs and gestures (op. cit. page 132.)... As the voice was used more and more, the vocal organs would have been strengthened and perfected through the principle of the inherited effects of use; and this would have reacted on the power of speech." (Op. cit. page 133.) On man's own instinctive cries, he has more to say in "The Expression of the Emotions". (Page 93 (Popular Edition, 1904) and elsewhere.) These remarks have been utilised by Prof. Jespersen of Copenhagen in propounding an ingenious theory of his own to the effect that speech develops out of singing. ("Progress in Language", page 361, London, 1894.) For many years and in many books Max Muller argued against Darwin's views on evolution on the one ground that thought is impossible without speech; consequently as speech is confined to the human race, there is a gulf which cannot be bridged between man and all other creatures. (Some interesting comments on the theory will be found in a lecture on "Thought and Language" in Samuel Butler's "Essays on Life, Art and Science", London, 1908.) On the title-page of his "Science of Thought" he put the two sentences "No Reason without Language: No Language without Reason." It may be readily admitted that the second dictum is true, that no language properly so-called can exist without reason. Various birds can learn to repeat words or sentences used by their masters or mistresses. In most cases probably the birds do not attach their proper meaning to the words they have learnt; they repeat them in season and out of season, sometimes apparently for their own amusement, generally in the expectation, raised by past experience, of being rewarded for their proficiency. But even here it is difficult to prove a universal negative, and most possessors of such pets would repudiate indignantly the statement that the bird did not understand what was said to it, and would also contend that in many cases the words which it used were employed in their ordinary meaning. The first dictum seems to be inconsistent with fact. The case of deaf mutes, such as Laura Bridgeman, who became well educated, or the still more extraordinary case of Helen Keller, deaf, dumb, and blind, who in spite of these disadvantages has learnt not only to reason but to reason better than the average of persons possessed of all their senses, goes to show that language and reason are not necessarily always in combination. Reason is but the conscious adaptation of means to ends, and so defined is a faculty which cannot be denied to many of the lower animals. In these days when so many books on Animal Intelligence are issued from the press, it seems unnecessary to labour the point. Yet none of these animals, except by parrot-imitation, makes use of speech, because man alone possesses in a sufficient degree of development the centres of nervous energy which are required for the working of articulation in speech. On this subject much investigation was carried on during the last years of Darwin's life and much more in the period since his death. As early as 1861 Broca, following up observations made by earlier French writers, located the centre of articulate speech in the third left frontal convolution of the brain. In 1876 he more definitely fixed the organ of speech in "the posterior two-fifths of the third frontal convolution" (Macnamara, "Human Speech", page 197, London, 1908.), both sides and not merely the left being concerned in speech production. Owing however to the greater use by most human beings of the right side of the body, the left side of the brain, which is the motor centre for the right side of the body, is more highly developed than its right side, which moves the left side of the body. The investigations of Professors Ferrier, Sherrington and Grunbaum have still more precisely defined the relations between brain areas and certain groups of muscles. One form of aphasia is the result of injury to or disease in the third frontal convolution because the motor centre is no longer equal to the task of setting the necessary muscles in motion. In the brain of idiots who are unable to speak, the centre for speech is not developed. (Op. cit. page 226.) In the anthropoid apes the brain is similarly defective, though it has been demonstrated by Professors Cunningham and Marchand "that there is a tendency, especially in the gorilla's brain, for the third frontal convolution to assume the human form... But if they possessed a centre for speech, those parts of the hemispheres of their brains which form the mechanism by which intelligence is elaborated are so ill-developed, as compared with the rest of their bodies, that we can not conceive, even with more perfect frontal convolutions, that these animals could formulate ideas expressible in intelligent speech." (Op. cit. page 223.) While Max Muller's theory is Shelley's "He gave man speech, and speech created thought, Which is the measure of the universe" ("Prometheus Unbound" II. 4.), it seems more probable that the development was just the opposite--that the development of new activities originated new thoughts which required new symbols to express them, symbols which may at first have been, even to a greater extent than with some of the lower races at present, sign language as much as articulation. When once the faculty of articulation was developed, which, though we cannot trace the process, was probably a very gradual growth, there is no reason to suppose that words developed in any other way then they do at present. An erroneous notion of the development of language has become widely spread through the adoption of the metaphorical term "roots" for the irreducible elements of human speech. Men never talked in roots; they talked in words. Many words of kindred meaning have a part in common, and a root is nothing but that common part stripped of all additions. In some cases it is obvious that one word is derived from another by the addition of a fresh element; in other cases it is impossible to say which of two kindred words is the more primitive. A root is merely a convenient term for an abstraction. The simplest word may be called a root, but it is nevertheless a word. How are new words added to a language in the present day? Some communities, like the Germans, prefer to construct new words for new ideas out of the old material existing in the language; others, like the English, prefer to go to the ancient languages of Greece and Rome for terms to express new ideas. The same chemical element is described in the two languages as sour stuff (Sauerstoff) and as oxygen. Both terms mean the same thing etymologically as well as in fact. On behalf of the German method, it may be contended that the new idea is more closely attached to already existing ideas, by being expressed in elements of the language which are intelligible even to the meanest capacity. For the English practice it may be argued that, if we coin a new word which means one thing, and one thing only, the idea which it expresses is more clearly defined than if it were expressed in popularly intelligible elements like "sour stuff." If the etymological value of words were always present in the minds of their users, "oxygen" would undoubtedly have an advantage over "sour stuff" as a technical term. But the tendency in language is to put two words of this kind which express but one idea under a single accent, and when this has taken place, no one but the student of language any longer observes what the elements really mean. When the ordinary man talks of a "blackbird" it is certainly not present to his consciousness that he is talking of a black bird, unless for some reason conversation has been dwelling upon the colour rather than other characteristics of the species. But, it may be said, words like "oxygen" are introduced by learned men, and do not represent the action of the man in the street, who, after all, is the author of most additions to the stock of human language. We may go back therefore some four centuries to a period, when scientific study was only in its infancy, and see what process was followed. With the discovery of America new products never seen before reached Europe, and these required names. Three of the most characteristic were tobacco, the potato, and the turkey. How did these come to be so named? The first people to import these products into Europe were naturally the Spanish discoverers. The first of these words--tobacco--appears in forms which differ only slightly in the languages of all civilised countries: Spanish tabaco, Italian tabacco, French tabac, Dutch and German tabak, Swedish tobak, etc. The word in the native dialect of Hayti is said to have been tabaco, but to have meant not the plant (According to William Barclay, "Nepenthes, or the Virtue of Tobacco", Edinburgh, 1614, "the countrey which God hath honoured and blessed with this happie and holy herbe doth call it in their native language 'Petum'.") but the pipe in which it was smoked. It thus illustrates a frequent feature of borrowing--that the word is not borrowed in its proper signification, but in some sense closely allied thereto, which a foreigner, understanding the language with difficulty, might readily mistake for the real meaning. Thus the Hindu practice of burning a wife upon the funeral pyre of her husband is called in English "suttee", this word being in fact but the phonetic spelling of the Sanskrit "sati", "a virtuous woman," and passing into its English meaning because formerly the practice of self-immolation by a wife was regarded as the highest virtue. The name of the potato exhibits greater variety. The English name was borrowed from the Spanish "patata", which was itself borrowed from a native word for the "yam" in the dialect of Hayti. The potato appeared early in Italy, for the mariners of Genoa actively followed the footsteps of their countryman Columbus in exploring America. In Italian generally the form "patata" has survived. The tubers, however, also suggested a resemblance to truffles, so that the Italian word "tartufolo", a diminutive of the Italian modification of the Latin "terrae tuber" was applied to them. In the language of the Rhaetian Alps this word appears as "tartufel". From there it seems to have passed into Germany where potatoes were not cultivated extensively till the eighteenth century, and "tartufel" has in later times through some popular etymology been metamorphosed into "Kartoffel". In France the shape of the tubers suggested the name of earth-apple (pomme de terre), a name also adopted in Dutch (aard-appel), while dialectically in German a form "Grumbire" appears, which is a corruption of "Grund-birne", "ground pear". (Kluge "Etymologisches Worterbuch der deutschen Sprache" (Strassburg), s.v. "Kartoffel".) Here half the languages have adopted the original American word for an allied plant, while others have adopted a name originating in some more or less fanciful resemblance discovered in the tubers; the Germans alone in Western Europe, failing to see any meaning in their borrowed name, have modified it almost beyond recognition. To this English supplies an exact parallel in "parsnep" which, though representing the Latin "pastinaca" through the Old French "pastenaque", was first assimilated in the last syllable to the "nep" of "turnep" ("pasneppe" in Elizabethan English), and later had an "r" introduced into the first syllable, apparently on the analogy of "parsley". The turkey on the other hand seems never to be found with its original American name. In England, as the name implies, the turkey cock was regarded as having come from the land of the Turks. The bird no doubt spread over Europe from the Italian seaports. The mistake, therefore, was not unnatural, seeing that these towns conducted a great trade with the Levant, while the fact that America when first discovered was identified with India helped to increase the confusion. Thus in French the "coq d'Inde" was abbreviated to "d'Inde" much as "turkey cock" was to "turkey"; the next stage was to identify "dinde" as a feminine word and create a new "dindon" on the analogy of "chapon" as the masculine. In Italian the name "gallo d'India" besides survives, while in German the name "Truthahn" seems to be derived onomatopoetically from the bird's cry, though a dialectic "Calecutischer Hahn" specifies erroneously an origin for the bird from the Indian Calicut. In the Spanish "pavo", on the other hand, there is a curious confusion with the peacock. Thus in these names for objects of common knowledge, the introduction of which into Europe can be dated with tolerable definiteness, we see evinced the methods by which in remoter ages objects were named. The words were borrowed from the community whence came the new object, or the real or fancied resemblance to some known object gave the name, or again popular etymology might convert the unknown term into something that at least approached in sound a well-known word. "The Origin of Species" had not long been published when the parallelism of development in natural species and in languages struck investigators. At the time, one of the foremost German philologists was August Schleicher, Professor at Jena. He was himself keenly interested in the natural sciences, and amongst his colleagues was Ernst Haeckel, the protagonist in Germany of the Darwinian theory. How the new ideas struck Schleicher may be seen from the following sentences by his colleague Haeckel. "Speech is a physiological function of the human organism, and has been developed simultaneously with its organs, the larynx and tongue, and with the functions of the brain. Hence it will be quite natural to find in the evolution and classification of languages the same features as in the evolution and classification of organic species. The various groups of languages that are distinguished in philology as primitive, fundamental, parent, and daughter languages, dialects, etc., correspond entirely in their development to the different categories which we classify in zoology and botany as stems, classes, orders, families, genera, species and varieties. The relation of these groups, partly coordinate and partly subordinate, in the general scheme is just the same in both cases; and the evolution follows the same lines in both." (Haeckel, "The Evolution of Man", page 485, London, 1905. This represents Schleicher's own words: Was die Naturforscher als Gattung bezeichnen wurden, heisst bei den Glottikern Sprachstamm, auch Sprachsippe; naher verwandte Gattungen bezeichnen sie wohl auch als Sprachfamilien einer Sippe oder eines Sprachstammes... Die Arten einer Gattung nennen wir Sprachen eines Stammes; die Unterarten einer Art sind bei uns die Dialekte oder Mundarten einer Sprache; den Varietaten und Spielarten entsprechen die Untermundarten oder Nebenmundarten und endlich den einzelnen Individuen die Sprechweise der einzelnen die Sprachen redenden Menschen. "Die Darwinische Theorie und die Sprachwissenschaft", Weimar, 1863, page 12 f. Darwin makes a more cautious statement about the classification of languages in "The Origin of Species", page 578, (Popular Edition, 1900).) These views were set forth in an open letter addressed to Haeckel in 1863 by Schleicher entitled, "The Darwinian theory and the science of language". Unfortunately Schleicher's views went a good deal farther than is indicated in the extract given above. He appended to the pamphlet a genealogical tree of the Indo-Germanic languages which, though to a large extent confirmed by later research, by the dichotomy of each branch into two other branches, led the unwary reader to suppose their phylogeny (to use Professor Haeckel's term) was more regular than our evidence warrants. Without qualification Schleicher declared languages to be "natural organisms which originated unconditioned by the human will, developed according to definite laws, grow old and die; they also are characterised by that series of phenomena which we designate by the term 'Life.' Consequently Glottic, the science of language, is a natural science; its method is in general the same as that of the other natural sciences." ("Die Darwinische Theorie", page 6 f.) In accordance with this view he declared (op. cit. page 23.) that the root in language might be compared with the simple cell in physiology, the linguistic simple cell or root being as yet not differentiated into special organs for the function of noun, verb, etc. In this probably all recent philologists admit that Schleicher went too far. One of the most fertile theories in the modern science of language originated with him, and was further developed by his pupil, August Leskien ("Die Declination im Slavisch-litanischen und Germanischen", Leipzig, 1876; Osthoff and Brugmann, "Morphologische Untersuchungen", I. (Introduction), 1878. The general principles of this school were formulated (1880) in a fuller form in H. Paul's "Prinzipien der Sprachgeschichte", Halle (3rd edition, 1898). Paul and Wundt (in his "Volkerpsychologie") deal largely with the same matter, but begin their investigations from different points of view, Paul being a philologist with leanings to philosophy and Wundt a philosopher interested in language.), and by Leskien's colleagues and friends, Brugmann and Osthoff. This was the principle that phonetic laws have no exceptions. Under the influence of this generalisation much greater precision in etymology was insisted upon, and a new and remarkably active period in the study of language began. Stated broadly in the fashion given above the principle is not true. A more accurate statement would be that an original sound is represented in a given dialect at a given time and in a given environment only in one way; provided that the development of the original sound into its representation in the given dialect has not been influenced by the working of analogy. It is this proviso that is most important for the characterisation of the science of language. As I have said elsewhere, it is at this point that this science parts company with the natural sciences. "If the chemist compounds two pure simple elements, there can be but one result, and no power of the chemist can prevent it. But the minds of men do act upon the sounds which they produce. The result is that, when this happens, the phonetic law which would have acted in the case is stopped, and this particular form enters on the same course of development as other forms to which it does not belong." (P. Giles, "Short Manual of Comparative Philology", 2nd edition, page 57, London, 1901.) Schleicher was wrong in defining a language to be an organism in the sense in which a living being is an organism. Regarded physiologically, language is a function or potentiality of certain human organs; regarded from the point of view of the community it is of the nature of an institution. (This view of language is worked out at some length by Prof. W.D. Whitney in an article in the "Contemporary Review" for 1875, page 713 ff. This article forms part of a controversy with Max Muller, which is partly concerned with Darwin's views on language. He criticises Schleicher's views severely in his "Oriental and Linguistic Studies", page 298 ff., New York, 1873. In this volume will be found criticisms of various other views mentioned in this essay.) More than most influences it conduces to the binding together of the elements that form a state. That geographical or other causes may effectively counteract the influence of identity of language is obvious. One need only read the history of ancient Greece, or observe the existing political separation of Germany and Austria, of Great Britain and the United States of America. But however analogous to an organism, language is not an organism. In a less degree Schleicher, by defining languages as such, committed the same mistake which Bluntschli made regarding the State, and which led him to declare that the State is by nature masculine and the Church feminine. (Bluntschli, "Theory of the State", page 24, Second English Edition, Oxford, 1892.) The views of Schleicher were to some extent injurious to the proper methods of linguistic study. But this misfortune was much more than fully compensated by the inspiration which his ideas, collected and modified by his disciples, had upon the science. In spite of the difference which the psychological element represented by analogy makes between the science of language and the natural sciences, we are entitled to say of it as Schleicher said of Darwin's theory of the origin of species, "it depends upon observation, and is essentially an attempt at a history of development." Other questions there are in connection with language and evolution which require investigation--the survival of one amongst several competing words (e.g. why German keeps only as a high poetic word "ross", which is identical in origin with the English work-a-day "horse", and replaces it by "pferd", whose congener the English "palfrey" is almost confined to poetry and romance), the persistence of evolution till it becomes revolution in languages like English or Persian which have practically ceased to be inflectional languages, and many other problems. Into these Darwin did not enter, and they require a fuller investigation than is possible within the limits of the present paper. XXVII. DARWINISM AND HISTORY. By J.B. Bury, Litt.D., LL.D. Regius Professor of Modern History in the University of Cambridge. 1. Evolution, and the principles associated with the Darwinian theory, could not fail to exert a considerable influence on the studies connected with the history of civilised man. The speculations which are known as "philosophy of history," as well as the sciences of anthropology, ethnography, and sociology (sciences which though they stand on their own feet are for the historian auxiliary), have been deeply affected by these principles. Historiographers, indeed, have with few exceptions made little attempt to apply them; but the growth of historical study in the nineteenth century has been determined and characterised by the same general principle which has underlain the simultaneous developments of the study of nature, namely the GENETIC idea. The "historical" conception of nature, which has produced the history of the solar system, the story of the earth, the genealogies of telluric organisms, and has revolutionised natural science, belongs to the same order of thought as the conception of human history as a continuous, genetic, causal process--a conception which has revolutionised historical research and made it scientific. Before proceeding to consider the application of evolutional principles, it will be pertinent to notice the rise of this new view. 2. With the Greeks and Romans history had been either a descriptive record or had been written in practical interests. The most eminent of the ancient historians were pragmatical; that is, they regarded history as an instructress in statesmanship, or in the art of war, or in morals. Their records reached back such a short way, their experience was so brief, that they never attained to the conception of continuous process, or realised the significance of time; and they never viewed the history of human societies as a phenomenon to be investigated for its own sake. In the middle ages there was still less chance of the emergence of the ideas of progress and development. Such notions were excluded by the fundamental doctrines of the dominant religion which bounded and bound men's minds. As the course of history was held to be determined from hour to hour by the arbitrary will of an extra-cosmic person, there could be no self-contained causal development, only a dispensation imposed from without. And as it was believed that the world was within no great distance from the end of this dispensation, there was no motive to take much interest in understanding the temporal, which was to be only temporary. The intellectual movements of the fifteenth and sixteenth centuries prepared the way for a new conception, but it did not emerge immediately. The historians of the Renaissance period simply reverted to the ancient pragmatical view. For Machiavelli, exactly as for Thucydides and Polybius, the use of studying history was instruction in the art of politics. The Renaissance itself was the appearance of a new culture, different from anything that had gone before; but at the time men were not conscious of this; they saw clearly that the traditions of classical antiquity had been lost for a long period, and they were seeking to revive them, but otherwise they did not perceive that the world had moved, and that their own spirit, culture, and conditions were entirely unlike those of the thirteenth century. It was hardly till the seventeenth century that the presence of a new age, as different from the middle ages as from the ages of Greece and Rome, was fully realised. It was then that the triple division of ancient, medieval, and modern was first applied to the history of western civilisation. Whatever objections may be urged against this division, which has now become almost a category of thought, it marks a most significant advance in man's view of his own past. He has become conscious of the immense changes in civilisation which have come about slowly in the course of time, and history confronts him with a new aspect. He has to explain how those changes have been produced, how the transformations were effected. The appearance of this problem was almost simultaneous with the rise of rationalism, and the great historians and thinkers of the eighteenth century, such as Montesquieu, Voltaire, Gibbon, attempted to explain the movement of civilisation by purely natural causes. These brilliant writers prepared the way for the genetic history of the following century. But in the spirit of the Aufklarung, that eighteenth-century Enlightenment to which they belonged, they were concerned to judge all phenomena before the tribunal of reason; and the apotheosis of "reason" tended to foster a certain superior a priori attitude, which was not favourable to objective treatment and was incompatible with a "historical sense." Moreover the traditions of pragmatical historiography had by no means disappeared. 3. In the first quarter of the nineteenth century the meaning of genetic history was fully realised. "Genetic" perhaps is as good a word as can be found for the conception which in this century was applied to so many branches of knowledge in the spheres both of nature and of mind. It does not commit us to the doctrine proper of evolution, nor yet to any teleological hypothesis such as is implied in "progress." For history it meant that the present condition of the human race is simply and strictly the result of a causal series (or set of causal series)--a continuous succession of changes, where each state arises causally out of the preceding; and that the business of historians is to trace this genetic process, to explain each change, and ultimately to grasp the complete development of the life of humanity. Three influential writers, who appeared at this stage and helped to initiate a new period of research, may specially be mentioned. Ranke in 1824 definitely repudiated the pragmatical view which ascribes to history the duties of an instructress, and with no less decision renounced the function, assumed by the historians of the Aufklarung, to judge the past; it was his business, he said, merely to show how things really happened. Niebuhr was already working in the same spirit and did more than any other writer to establish the principle that historical transactions must be related to the ideas and conditions of their age. Savigny about the same time founded the "historical school" of law. He sought to show that law was not the creation of an enlightened will, but grew out of custom and was developed by a series of adaptations and rejections, thus applying the conception of evolution. He helped to diffuse the notion that all the institutions of a society or a notion are as closely interconnected as the parts of a living organism. 4. The conception of the history of man as a causal development meant the elevation of historical inquiry to the dignity of a science. Just as the study of bees cannot become scientific so long as the student's interest in them is only to procure honey or to derive moral lessons from the labours of "the little busy bee," so the history of human societies cannot become the object of pure scientific investigation so long as man estimates its value in pragmatical scales. Nor can it become a science until it is conceived as lying entirely within a sphere in which the law of cause and effect has unreserved and unrestricted dominion. On the other hand, once history is envisaged as a causal process, which contains within itself the explanation of the development of man from his primitive state to the point which he has reached, such a process necessarily becomes the object of scientific investigation and the interest in it is scientific curiosity. At the same time, the instruments were sharpened and refined. Here Wolf, a philologist with historical instinct, was a pioneer. His "Prolegomena" to Homer (1795) announced new modes of attack. Historical investigation was soon transformed by the elaboration of new methods. 5. "Progress" involves a judgment of value, which is not involved in the conception of history as a genetic process. It is also an idea distinct from that of evolution. Nevertheless it is closely related to the ideas which revolutionised history at the beginning of the last century; it swam into men's ken simultaneously; and it helped effectively to establish the notion of history as a continuous process and to emphasise the significance of time. Passing over earlier anticipations, I may point to a "Discours" of Turgot (1750), where history is presented as a process in which "the total mass of the human race" "marches continually though sometimes slowly to an ever increasing perfection." That is a clear statement of the conception which Turgot's friend Condorcet elaborated in the famous work, published in 1795, "Esquisse d'un tableau historique des progres de l'esprit humain". This work first treated with explicit fulness the idea to which a leading role was to fall in the ideology of the nineteenth century. Condorcet's book reflects the triumphs of the Tiers etat, whose growing importance had also inspired Turgot; it was the political changes in the eighteenth century which led to the doctrine, emphatically formulated by Condorcet, that the masses are the most important element in the historical process. I dwell on this because, though Condorcet had no idea of evolution, the pre-dominant importance of the masses was the assumption which made it possible to apply evolutional principles to history. And it enabled Condorcet himself to maintain that the history of civilisation, a progress still far from being complete, was a development conditioned by general laws. 6. The assimilation of society to an organism, which was a governing notion in the school of Savigny, and the conception of progress, combined to produce the idea of an organic development, in which the historian has to determine the central principle or leading character. This is illustrated by the apotheosis of democracy in Tocqueville's "Democratie en Amerique", where the theory is maintained that "the gradual and progressive development of equality is at once the past and the future of the history of men." The same two principles are combined in the doctrine of Spencer (who held that society is an organism, though he also contemplated its being what he calls a "super-organic aggregate") (A society presents suggestive analogies with an organism, but it certainly is not an organism, and sociologists who draw inferences from the assumption of its organic nature must fall into error. A vital organism and a society are radically distinguished by the fact that the individual components of the former, namely the cells, are morphologically as well as functionally differentiated, whereas the individuals which compose a society are morphologically homogeneous and only functionally differentiated. The resemblances and the differences are worked out in E. de Majewski's striking book "La Science de la Civilisation", Paris, 1908.), that social evolution is a progressive change from militarism to industrialism. 7. the idea of development assumed another form in the speculations of German idealism. Hegel conceived the successive periods of history as corresponding to the ascending phases or ideas in the self-evolution of his Absolute Being. His "Lectures on the Philosophy of History" were published in 1837 after his death. His philosophy had a considerable effect, direct and indirect, on the treatment of history by historians, and although he was superficial and unscientific himself in dealing with historical phenomena, he contributed much towards making the idea of historical development familiar. Ranke was influenced, if not by Hegel himself, at least by the Idealistic philosophies of which Hegel's was the greatest. He was inclined to conceive the stages in the process of history as marked by incarnations, as it were, of ideas, and sometimes speaks as if the ideas were independent forces, with hands and feet. But while Hegel determined his ideas by a priori logic, Ranke obtained his by induction--by a strict investigation of the phenomena; so that he was scientific in his method and work, and was influenced by Hegelian prepossessions only in the kind of significance which he was disposed to ascribe to his results. It is to be noted that the theory of Hegel implied a judgment of value; the movement was a progress towards perfection. 8. In France, Comte approached the subject from a different side, and exercised, outside Germany, a far wider influence than Hegel. The 4th volume of his "Cours de philosophie positive", which appeared in 1839, created sociology and treated history as a part of this new science, namely as "social dynamics." Comte sought the key for unfolding historical development, in what he called the social-psychological point of view, and he worked out the two ideas which had been enunciated by Condorcet: that the historian's attention should be directed not, as hitherto, principally to eminent individuals, but to the collective behaviour of the masses, as being the most important element in the process; and that, as in nature, so in history, there are general laws, necessary and constant, which condition the development. The two points are intimately connected, for it is only when the masses are moved into the foreground that regularity, uniformity, and law can be conceived as applicable. To determine the social-psychological laws which have controlled the development is, according to Comte, the task of sociologists and historians. 9. The hypothesis of general laws operative in history was carried further in a book which appeared in England twenty years later and exercised an influence in Europe far beyond its intrinsic merit, Buckle's "History of Civilisation in England" (1857-61). Buckle owed much to Comte, and followed him, or rather outdid him, in regarding intellect as the most important factor conditioning the upward development of man, so that progress, according to him, consisted in the victory of the intellectual over the moral laws. 10. The tendency of Comte and Buckle to assimilate history to the sciences of nature by reducing it to general "laws," derived stimulus and plausibility from the vista offered by the study of statistics, in which the Belgian Quetelet, whose book "Sur l'homme" appeared in 1835, discerned endless possibilities. The astonishing uniformities which statistical inquiry disclosed led to the belief that it was only a question of collecting a sufficient amount of statistical material, to enable us to predict how a given social group will act in a particular case. Bourdeau, a disciple of this school, looks forward to the time when historical science will become entirely quantitative. The actions of prominent individuals, which are generally considered to have altered or determined the course of things, are obviously not amenable to statistical computation or explicable by general laws. Thinkers like Buckle sought to minimise their importance or explain them away. 11. These indications may suffice to show that the new efforts to interpret history which marked the first half of the nineteenth century were governed by conceptions closely related to those which were current in the field of natural science and which resulted in the doctrine of evolution. The genetic principle, progressive development, general laws, the significance of time, the conception of society as an organic aggregate, the metaphysical theory of history as the self-evolution of spirit,--all these ideas show that historical inquiry had been advancing independently on somewhat parallel lines to the sciences of nature. It was necessary to bring this out in order to appreciate the influence of Darwinism. 12. In the course of the dozen years which elapsed between the appearances of "The Origin of Species" (observe that the first volume of Buckle's work was published just two years before) and of "The Descent of Man" (1871), the hypothesis of Lamarck that man is the co-descendant with other species of some lower extinct form was admitted to have been raised to the rank of an established fact by most thinkers whose brains were not working under the constraint of theological authority. One important effect of the discovery of this fact (I am not speaking now of the Darwinian explanation) was to assign to history a definite place in the coordinated whole of knowledge, and relate it more closely to other sciences. It had indeed a defined logical place in systems such as Hegel's and Comte's; but Darwinism certified its standing convincingly and without more ado. The prevailing doctrine that man was created ex abrupto had placed history in an isolated position, disconnected with the sciences of nature. Anthropology, which deals with the animal anthropos, now comes into line with zoology, and brings it into relation with history. (It is to be observed that history is not only different in scope but) not coextensive with anthropology IN TIME. For it deals only with the development of man in societies, whereas anthropology includes in its definition the proto-anthropic period when anthropos was still non-social, whether he lived in herds like the chimpanzee, or alone like the male ourang-outang. (It has been well shown by Majewski that congregations--herds, flocks, packs, etc.--of animals are not SOCIETIES; the characteristic of a society is differentiation of function. Bee hives, ant hills, may be called quasi-societies; but in their case the classes which perform distinct functions are morphologically different.) Man's condition at the present day is the result of a series of transformations, going back to the most primitive phase of society, which is the ideal (unattainable) beginning of history. But that beginning had emerged without any breach of continuity from a development which carries us back to a quadrimane ancestor, still further back (according to Darwin's conjecture) to a marine animal of the ascidian type, and then through remoter periods to the lowest form of organism. It is essential in this theory that though links have been lost there was no break in the gradual development; and this conception of a continuous progress in the evolution of life, resulting in the appearance of uncivilised Anthropos, helped to reinforce, and increase a belief in, the conception of the history of civilised Anthropos as itself also a continuous progressive development. 13. Thus the diffusion of the Darwinian theory of the origin of man, by emphasising the idea of continuity and breaking down the barriers between the human and animal kingdoms, has had an important effect in establishing the position of history among the sciences which deal with telluric development. The perspective of history is merged in a larger perspective of development. As one of the objects of biology is to find the exact steps in the genealogy of man from the lowest organic form, so the scope of history is to determine the stages in the unique causal series from the most rudimentary to the present state of human civilisation. It is to be observed that the interest in historical research implied by this conception need not be that of Comte. In the Positive Philosophy history is part of sociology; the interest in it is to discover the sociological laws. In the view of which I have just spoken, history is permitted to be an end in itself; the reconstruction of the genetic process is an independent interest. For the purpose of the reconstruction, sociology, as well as physical geography, biology, psychology, is necessary; the sociologist and the historian play into each other's hands; but the object of the former is to establish generalisations; the aim of the latter is to trace in detail a singular causal sequence. 14. The success of the evolutional theory helped to discredit the assumption or at least the invocation of transcendent causes. Philosophically of course it is compatible with theism, but historians have for the most part desisted from invoking the naive conception of a "god in history" to explain historical movements. A historian may be a theist; but, so far as his work is concerned, this particular belief is otiose. Otherwise indeed (as was remarked above) history could not be a science; for with a deus ex machina who can be brought on the stage to solve difficulties scientific treatment is a farce. The transcendent element had appeared in a more subtle form through the influence of German philosophy. I noticed how Ranke is prone to refer to ideas as if they were transcendent existences manifesting themselves in the successive movements of history. It is intelligible to speak of certain ideas as controlling, in a given period,--for instance, the idea of nationality; but from the scientific point of view, such ideas have no existence outside the minds of individuals and are purely psychical forces; and a historical "idea," if it does not exist in this form, is merely a way of expressing a synthesis of the historian himself. 15. From the more general influence of Darwinism on the place of history in the system of human knowledge, we may turn to the influence of the principles and methods by which Darwin explained development. It had been recognised even by ancient writers (such as Aristotle and Polybius) that physical circumstances (geography, climate) were factors conditioning the character and history of a race or society. In the sixteenth century Bodin emphasised these factors, and many subsequent writers took them into account. The investigations of Darwin, which brought them into the foreground, naturally promoted attempts to discover in them the chief key to the growth of civilisation. Comte had expressly denounced the notion that the biological methods of Lamarck could be applied to social man. Buckle had taken account of natural influences, but had relegated them to a secondary plane, compared with psychological factors. But the Darwinian theory made it tempting to explain the development of civilisation in terms of "adaptation to environment," "struggle for existence," "natural selection," "survival of the fittest," etc. (Recently O. Seeck has applied these principles to the decline of Graeco-Roman civilisation in his "Untergang der antiken Welt", 2 volumes, Berlin, 1895, 1901.) The operation of these principles cannot be denied. Man is still an animal, subject to zoological as well as mechanical laws. The dark influence of heredity continues to be effective; and psychical development had begun in lower organic forms,--perhaps with life itself. The organic and the social struggles for existence are manifestations of the same principle. Environment and climatic influence must be called in to explain not only the differentiation of the great racial sections of humanity, but also the varieties within these sub-species and, it may be, the assimilation of distinct varieties. Ritter's "Anthropogeography" has opened a useful line of research. But on the other hand, it is urged that, in explaining the course of history, these principles do not take us very far, and that it is chiefly for the primitive ultra-prehistoric period that they can account for human development. It may be said that, so far as concerns the actions and movements of men which are the subject of recorded history, physical environment has ceased to act mechanically, and in order to affect their actions must affect their wills first; and that this psychical character of the causal relations substantially alters the problem. The development of human societies, it may be argued, derives a completely new character from the dominance of the conscious psychical element, creating as it does new conditions (inventions, social institutions, etc.) which limit and counteract the operation of natural selection, and control and modify the influence of physical environment. Most thinkers agree now that the chief clews to the growth of civilisation must be sought in the psychological sphere. Imitation, for instance, is a principle which is probably more significant for the explanation of human development than natural selection. Darwin himself was conscious that his principles had only a very restricted application in this sphere, as is evident from his cautious and tentative remarks in the 5th chapter of his "Descent of Man". He applied natural selection to the growth of the intellectual faculties and of the fundamental social instincts, and also to the differentiation of the great races or "sub-species" (Caucasian, African, etc.) which differ in anthropological character. (Darwinian formulae may be suggestive by way of analogy. For instance, it is characteristic of social advance that a multitude of inventions, schemes and plans are framed which are never carried out, similar to, or designed for the same end as, an invention or plan which is actually adopted because it has chanced to suit better the particular conditions of the hour (just as the works accomplished by an individual statesman, artist or savant are usually only a residue of the numerous projects conceived by his brain). This process in which so much abortive production occurs is analogous to elimination by natural selection.) 16. But if it is admitted that the governing factors which concern the student of social development are of the psychical order, the preliminary success of natural science in explaining organic evolution by general principles encouraged sociologists to hope that social evolution could be explained on general principles also. The idea of Condorcet, Buckle, and others, that history could be assimilated to the natural sciences was powerfully reinforced, and the notion that the actual historical process, and every social movement involved in it, can be accounted for by sociological generalisations, so-called "laws," is still entertained by many, in one form or another. Dissentients from this view do not deny that the generalisations at which the sociologist arrives by the comparative method, by the analysis of social factors, and by psychological deduction may be an aid to the historian; but they deny that such uniformities are laws or contain an explanation of the phenomena. They can point to the element of chance coincidence. This element must have played a part in the events of organic evolution, but it has probably in a larger measure helped to determine events in social evolution. The collision of two unconnected sequences may be fraught with great results. The sudden death of a leader or a marriage without issue, to take simple cases, has again and again led to permanent political consequences. More emphasis is laid on the decisive actions of individuals, which cannot be reduced under generalisations and which deflect the course of events. If the significance of the individual will had been exaggerated to the neglect of the collective activity of the social aggregate before Condorcet, his doctrine tended to eliminate as unimportant the roles of prominent men, and by means of this elimination it was possible to found sociology. But it may be urged that it is patent on the face of history that its course has constantly been shaped and modified by the wills of individuals (We can ignore here the metaphysical question of freewill and determinism. For the character of the individual's brain depends in any case on ante-natal accidents and coincidences, and so it may be said that the role of individuals ultimately depends on chance,--the accidental coincidence of independent sequences.), which are by no means always the expression of the collective will; and that the appearance of such personalities at the given moments is not a necessary outcome of the conditions and cannot be deduced. Nor is there any proof that, if such and such an individual had not been born, some one else would have arisen to do what he did. In some cases there is no reason to think that what happened need ever have come to pass. In other cases, it seems evident that the actual change was inevitable, but in default of the man who initiated and guided it, it might have been postponed, and, postponed or not, might have borne a different cachet. I may illustrate by an instance which has just come under my notice. Modern painting was founded by Giotto, and the Italian expedition of Charles VIII, near the close of the sixteenth century, introduced into France the fashion of imitating Italian painters. But for Giotto and Charles VIII, French painting might have been very different. It may be said that "if Giotto had not appeared, some other great initiator would have played a role analogous to his, and that without Charles VIII there would have been the commerce with Italy, which in the long run would have sufficed to place France in relation with Italian artists. But the equivalent of Giotto might have been deferred for a century and probably would have been different; and commercial relations would have required ages to produce the rayonnement imitatif of Italian art in France, which the expedition of the royal adventurer provoked in a few years." (I have taken this example from G. Tarde's "La logique sociale" 2 (page 403), Paris, 1904, where it is used for quite a different purpose.) Instances furnished by political history are simply endless. Can we conjecture how events would have moved if the son of Philip of Macedon had been an incompetent? The aggressive action of Prussia which astonished Europe in 1740 determined the subsequent history of Germany; but that action was anything but inevitable; it depended entirely on the personality of Frederick the Great. Hence it may be argued that the action of individual wills is a determining and disturbing factor, too significant and effective to allow history to be grasped by sociological formulae. The types and general forms of development which the sociologist attempts to disengage can only assist the historian in understanding the actual course of events. It is in the special domains of economic history and Culturgeschichte which have come to the front in modern times that generalisation is most fruitful, but even in these it may be contended that it furnishes only partial explanations. 17. The truth is that Darwinism itself offers the best illustration of the insufficiency of general laws to account for historical development. The part played by coincidence, and the part played by individuals--limited by, and related to, general social conditions--render it impossible to deduce the course of the past history of man or to predict the future. But it is just the same with organic development. Darwin (or any other zoologist) could not deduce the actual course of evolution from general principles. Given an organism and its environment, he could not show that it must evolve into a more complex organism of a definite pre-determined type; knowing what it has evolved into, he could attempt to discover and assign the determining causes. General principles do not account for a particular sequence; they embody necessary conditions; but there is a chapter of accidents too. It is the same in the case of history. 18. Among the evolutional attempts to subsume the course of history under general syntheses, perhaps the most important is that of Lamprecht, whose "kulturhistorische Methode," which he has deduced from and applied to German history, exhibits the (indirect) influence of the Comtist school. It is based upon psychology, which, in his view, holds among the sciences of mind (Geisteswissenschaften) the same place (that of a Grundwissenschaft) which mechanics holds among the sciences of nature. History, by the same comparison, corresponds to biology, and, according to him, it can only become scientific if it is reduced to general concepts (Begriffe). Historical movements and events are of a psychical character, and Lamprecht conceives a given phase of civilisation as "a collective psychical condition (seelischer Gesamtzustand)" controlling the period, "a diapason which penetrates all psychical phenomena and thereby all historical events of the time." ("Die kulturhistorische Methode", Berlin, 1900, page 26.) He has worked out a series of such phases, "ages of changing psychical diapason," in his "Deutsche Geschichte" with the aim of showing that all the feelings and actions of each age can be explained by the diapason; and has attempted to prove that these diapasons are exhibited in other social developments, and are consequently not singular but typical. He maintains further that these ages succeed each other in a definite order; the principle being that the collective psychical development begins with the homogeneity of all the individual members of a society and, through heightened psychical activity, advances in the form of a continually increasing differentiation of the individuals (this is akin to the Spencerian formula). This process, evolving psychical freedom from psychical constraint, exhibits a series of psychical phenomena which define successive periods of civilisation. The process depends on two simple principles, that no idea can disappear without leaving behind it an effect or influence, and that all psychical life, whether in a person or a society, means change, the acquisition of new mental contents. It follows that the new have to come to terms with the old, and this leads to a synthesis which determines the character of a new age. Hence the ages of civilisation are defined as the "highest concepts for subsuming without exception all psychical phenomena of the development of human societies, that is, of all historical events." (Ibid. pages 28, 29.) Lamprecht deduces the idea of a special historical science, which might be called "historical ethnology," dealing with the ages of civilisation, and bearing the same relation to (descriptive or narrative) history as ethnology to ethnography. Such a science obviously corresponds to Comte's social dynamics, and the comparative method, on which Comte laid so much emphasis, is the principal instrument of Lamprecht. 19. I have dwelt on the fundamental ideas of Lamprecht, because they are not yet widely known in England, and because his system is the ablest product of the sociological school of historians. It carries the more weight as its author himself is a historical specialist, and his historical syntheses deserve the most careful consideration. But there is much in the process of development which on such assumptions is not explained, especially the initiative of individuals. Historical development does not proceed in a right line, without the choice of diverging. Again and again, several roads are open to it, of which it chooses one--why? On Lamprecht's method, we may be able to assign the conditions which limit the psychical activity of men at a particular stage of evolution, but within those limits the individual has so many options, such a wide room for moving, that the definition of those conditions, the "psychical diapasons," is only part of the explanation of the particular development. The heel of Achilles in all historical speculations of this class has been the role of the individual. The increasing prominence of economic history has tended to encourage the view that history can be explained in terms of general concepts or types. Marx and his school based their theory of human development on the conditions of production, by which, according to them, all social movements and historical changes are entirely controlled. The leading part which economic factors play in Lamprecht's system is significant, illustrating the fact that economic changes admit most readily this kind of treatment, because they have been less subject to direction or interference by individual pioneers. Perhaps it may be thought that the conception of SOCIAL ENVIRONMENT (essentially psychical), on which Lamprecht's "psychical diapasons" depend, is the most valuable and fertile conception that the historian owes to the suggestion of the science of biology--the conception of all particular historical actions and movements as (1) related to and conditioned by the social environment, and (2) gradually bringing about a transformation of that environment. But no given transformation can be proved to be necessary (pre-determined). And types of development do not represent laws; their meaning and value lie in the help they may give to the historian, in investigating a certain period of civilisation, to enable him to discover the interrelations among the diverse features which it presents. They are, as some one has said, an instrument of heuretic method. 20. The men engaged in special historical researches--which have been pursued unremittingly for a century past, according to scientific methods of investigating evidence (initiated by Wolf, Niebuhr, Ranke)--have for the most part worked on the assumptions of genetic history or at least followed in the footsteps of those who fully grasped the genetic point of view. But their aim has been to collect and sift evidence, and determine particular facts; comparatively few have given serious thought to the lines of research and the speculations which have been considered in this paper. They have been reasonably shy of compromising their work by applying theories which are still much debated and immature. But historiography cannot permanently evade the questions raised by these theories. One may venture to say that no historical change or transformation will be fully understood until it is explained how social environment acted on the individual components of the society (both immediately and by heredity), and how the individuals reacted upon their environment. The problem is psychical, but it is analogous to the main problem of the biologist. XXVIII. THE GENESIS OF DOUBLE STARS. By Sir George Darwin, K.C.B., F.R.S. Plumian Professor of Astronomy and Experimental Philosophy in the University of Cambridge. In ordinary speech a system of any sort is said to be stable when it cannot be upset easily, but the meaning attached to the word is usually somewhat vague. It is hardly surprising that this should be the case, when it is only within the last thirty years, and principally through the investigations of M. Poincare, that the conception of stability has, even for physicists, assumed a definiteness and clearness in which it was previously lacking. The laws which govern stability hold good in regions of the greatest diversity; they apply to the motion of planets round the sun, to the internal arrangement of those minute corpuscles of which each chemical atom is constructed, and to the forms of celestial bodies. In the present essay I shall attempt to consider the laws of stability as relating to the last case, and shall discuss the succession of shapes which may be assumed by celestial bodies in the course of their evolution. I believe further that homologous conceptions are applicable in the consideration of the transmutations of the various forms of animal and of vegetable life and in other regions of thought. Even if some of my readers should think that what I shall say on this head is fanciful, yet at least the exposition will serve to illustrate the meaning to be attached to the laws of stability in the physical universe. I propose, therefore, to begin this essay by a sketch of the principles of stability as they are now formulated by physicists. I. If a slight impulse be imparted to a system in equilibrium one of two consequences must ensue; either small oscillations of the system will be started, or the disturbance will increase without limit and the arrangement of the system will be completely changed. Thus a stick may be in equilibrium either when it hangs from a peg or when it is balanced on its point. If in the first case the stick is touched it will swing to and fro, but in the second case it will topple over. The first position is a stable one, the second is unstable. But this case is too simple to illustrate all that is implied by stability, and we must consider cases of stable and of unstable motion. Imagine a satellite and its planet, and consider each of them to be of indefinitely small size, in fact particles; then the satellite revolves round its planet in an ellipse. A small disturbance imparted to the satellite will only change the ellipse to a small amount, and so the motion is said to be stable. If, on the other hand, the disturbance were to make the satellite depart from its initial elliptic orbit in ever widening circuits, the motion would be unstable. This case affords an example of stable motion, but I have adduced it principally with the object of illustrating another point not immediately connected with stability, but important to a proper comprehension of the theory of stability. The motion of a satellite about its planet is one of revolution or rotation. When the satellite moves in an ellipse of any given degree of eccentricity, there is a certain amount of rotation in the system, technically called rotational momentum, and it is always the same at every part of the orbit. (Moment of momentum or rotational momentum is measured by the momentum of the satellite multiplied by the perpendicular from the planet on to the direction of the path of the satellite at any instant.) Now if we consider all the possible elliptic orbits of a satellite about its planet which have the same amount of "rotational momentum," we find that the major axis of the ellipse described will be different according to the amount of flattening (or the eccentricity) of the ellipse described. A figure titled "A 'family' of elliptic orbits with constant rotational momentum" (Fig. 1) illustrates for a given planet and satellite all such orbits with constant rotational momentum, and with all the major axes in the same direction. It will be observed that there is a continuous transformation from one orbit to the next, and that the whole forms a consecutive group, called by mathematicians "a family" of orbits. In this case the rotational momentum is constant and the position of any orbit in the family is determined by the length of the major axis of the ellipse; the classification is according to the major axis, but it might have been made according to anything else which would cause the orbit to be exactly determinate. I shall come later to the classification of all possible forms of ideal liquid stars, which have the same amount of rotational momentum, and the classification will then be made according to their densities, but the idea of orderly arrangement in a "family" is just the same. We thus arrive at the conception of a definite type of motion, with a constant amount of rotational momentum, and a classification of all members of the family, formed by all possible motions of that type, according to the value of some measurable quantity (this will hereafter be density) which determines the motion exactly. In the particular case of the elliptic motion used for illustration the motion was stable, but other cases of motion might be adduced in which the motion would be unstable, and it would be found that classification in a family and specification by some measurable quantity would be equally applicable. A complex mechanical system may be capable of motion in several distinct modes or types, and the motions corresponding to each such type may be arranged as before in families. For the sake of simplicity I will suppose that only two types are possible, so that there will only be two families; and the rotational momentum is to be constant. The two types of motion will have certain features in common which we denote in a sort of shorthand by the letter A. Similarly the two types may be described as A + a and A + b, so that a and b denote the specific differences which discriminate the families from one another. Now following in imagination the family of the type A + a, let us begin with the case where the specific difference a is well marked. As we cast our eyes along the series forming the family, we find the difference a becoming less conspicuous. It gradually dwindles until it disappears; beyond this point it either becomes reversed, or else the type has ceased to be a possible one. In our shorthand we have started with A + a, and have watched the characteristic a dwindling to zero. When it vanishes we have reached a type which may be specified as A; beyond this point the type would be A - a or would be impossible. Following the A + b type in the same way, b is at first well marked, it dwindles to zero, and finally may become negative. Hence in shorthand this second family may be described as A + b,... A,... A - b. In each family there is one single member which is indistinguishable from a member of the other family; it is called by Poincare a form of bifurcation. It is this conception of a form of bifurcation which forms the important consideration in problems dealing with the forms of liquid or gaseous bodies in rotation. But to return to the general question,--thus far the stability of these families has not been considered, and it is the stability which renders this way of looking at the matter so valuable. It may be proved that if before the point of bifurcation the type A + a was stable, then A + b must have been unstable. Further as a and b each diminish A + a becomes less pronouncedly stable, and A + b less unstable. On reaching the point of bifurcation A + a has just ceased to be stable, or what amounts to the same thing is just becoming unstable, and the converse is true of the A + b family. After passing the point of bifurcation A + a has become definitely unstable and A + b has become stable. Hence the point of bifurcation is also a point of "exchange of stabilities between the two types." (In order not to complicate unnecessarily this explanation of a general principle I have not stated fully all the cases that may occur. Thus: firstly, after bifurcation A + a may be an impossible type and A + a will then stop at this point; or secondly, A + b may have been an impossible type before bifurcation, and will only begin to be a real one after it; or thirdly, both A + a and A + b may be impossible after the point of bifurcation, in which case they coalesce and disappear. This last case shows that types arise and disappear in pairs, and that on appearance or before disappearance one must be stable and the other unstable.) In nature it is of course only the stable types of motion which can persist for more than a short time. Thus the task of the physical evolutionist is to determine the forms of bifurcation, at which he must, as it were, change carriages in the evolutionary journey so as always to follow the stable route. He must besides be able to indicate some natural process which shall correspond in effect to the ideal arrangement of the several types of motion in families with gradually changing specific differences. Although, as we shall see hereafter, it may frequently or even generally be impossible to specify with exactness the forms of bifurcation in the process of evolution, yet the conception is one of fundamental importance. The ideas involved in this sketch are no doubt somewhat recondite, but I hope to render them clearer to the non-mathematical reader by homologous considerations in other fields of thought (I considered this subject in my Presidential address to the British Association in 1905, "Report of the 75th Meeting of the British Assoc." (S. Africa, 1905), London, 1906, page 3. Some reviewers treated my speculations as fanciful, but as I believe that this was due generally to misapprehension, and as I hold that homologous considerations as to stability and instability are really applicable to evolution of all sorts, I have thought it well to return to the subject in the present paper.), and I shall pass on thence to illustrations which will teach us something of the evolution of stellar systems. States or governments are organised schemes of action amongst groups of men, and they belong to various types to which generic names, such as autocracy, aristocracy or democracy, are somewhat loosely applied. A definite type of government corresponds to one of our types of motion, and while retaining its type it undergoes a slow change as the civilisation and character of the people change, and as the relationship of the nation to other nations changes. In the language used before, the government belongs to a family, and as time advances we proceed through the successive members of the family. A government possesses a certain degree of stability--hardly measurable in numbers however--to resist disintegrating influences such as may arise from wars, famines, and internal dissensions. This stability gradually rises to a maximum and gradually declines. The degree of stability at any epoch will depend on the fitness of some leading feature of the government to suit the slowly altering circumstances, and that feature corresponds to the characteristic denoted by a in the physical problem. A time at length arrives when the stability vanishes, and the slightest shock will overturn the government. At this stage we have reached the crisis of a point of bifurcation, and there will then be some circumstance, apparently quite insignificant and almost unnoticed, which is such as to prevent the occurrence of anarchy. This circumstance or condition is what we typified as b. Insignificant although it may seem, it has started the government on a new career of stability by imparting to it a new type. It grows in importance, the form of government becomes obviously different, and its stability increases. Then in its turn this newly acquired stability declines, and we pass on to a new crisis or revolution. There is thus a series of "points of bifurcation" in history at which the continuity of political history is maintained by means of changes in the type of government. These ideas seem, to me at least, to give a true account of the history of states, and I contend that it is no mere fanciful analogy but a true homology, when in both realms of thought--the physical and the political--we perceive the existence of forms of bifurcation and of exchanges of stability. Further than this, I would ask whether the same train of ideas does not also apply to the evolution of animals? A species is well adapted to its environment when the individual can withstand the shocks of famine or the attacks and competition of other animals; it then possesses a high degree of stability. Most of the casual variations of individuals are indifferent, for they do not tell much either for or against success in life; they are small oscillations which leave the type unchanged. As circumstances change, the stability of the species may gradually dwindle through the insufficiency of some definite quality, on which in earlier times no such insistent demands were made. The individual animals will then tend to fail in the struggle for life, the numbers will dwindle and extinction may ensue. But it may be that some new variation, at first of insignificant importance, may just serve to turn the scale. A new type may be formed in which the variation in question is preserved and augmented; its stability may increase and in time a new species may be produced. At the risk of condemnation as a wanderer beyond my province into the region of biological evolution, I would say that this view accords with what I understand to be the views of some naturalists, who recognise the existence of critical periods in biological history at which extinction occurs or which form the starting-point for the formation of new species. Ought we not then to expect that long periods will elapse during which a type of animal will remain almost constant, followed by other periods, enormously long no doubt as measured in the life of man, of acute struggle for existence when the type will change more rapidly? This at least is the view suggested by the theory of stability in the physical universe. (I make no claim to extensive reading on this subject, but refer the reader for example to a paper by Professor A.A.W. Hubrecht on "De Vries's theory of Mutations", "Popular Science Monthly", July 1904, especially to page 213.) And now I propose to apply these ideas of stability to the theory of stellar evolution, and finally to illustrate them by certain recent observations of a very remarkable character. Stars and planets are formed of materials which yield to the enormous forces called into play by gravity and rotation. This is obviously true if they are gaseous or fluid, and even solid matter becomes plastic under sufficiently great stresses. Nothing approaching a complete study of the equilibrium of a heterogeneous star has yet been found possible, and we are driven to consider only bodies of simpler construction. I shall begin therefore by explaining what is known about the shapes which may be assumed by a mass of incompressible liquid of uniform density under the influences of gravity and of rotation. Such a liquid mass may be regarded as an ideal star, which resembles a real star in the fact that it is formed of gravitating and rotating matter, and because its shape results from the forces to which it is subject. It is unlike a star in that it possesses the attributes of incompressibility and of uniform density. The difference between the real and the ideal is doubtless great, yet the similarity is great enough to allow us to extend many of the conclusions as to ideal liquid stars to the conditions which must hold good in reality. Thus with the object of obtaining some insight into actuality, it is justifiable to discuss an avowedly ideal problem at some length. The attraction of gravity alone tends to make a mass of liquid assume the shape of a sphere, and the effects of rotation, summarised under the name of centrifugal force, are such that the liquid seeks to spread itself outwards from the axis of rotation. It is a singular fact that it is unnecessary to take any account of the size of the mass of liquid under consideration, because the shape assumed is exactly the same whether the mass be small or large, and this renders the statement of results much easier than would otherwise be the case. A mass of liquid at rest will obviously assume the shape of a sphere, under the influence of gravitation, and it is a stable form, because any oscillation of the liquid which might be started would gradually die away under the influence of friction, however small. If now we impart to the whole mass of liquid a small speed of rotation about some axis, which may be called the polar axis, in such a way that there are no internal currents and so that it spins in the same way as if it were solid, the shape will become slightly flattened like an orange. Although the earth and the other planets are not homogeneous they behave in the same way, and are flattened at the poles and protuberant at the equator. This shape may therefore conveniently be described as planetary. If the planetary body be slightly deformed the forces of restitution are slightly less than they were for the sphere; the shape is stable but somewhat less so than the sphere. We have then a planetary spheroid, rotating slowly, slightly flattened at the poles, with a high degree of stability, and possessing a certain amount of rotational momentum. Let us suppose this ideal liquid star to be somewhere in stellar space far removed from all other bodies; then it is subject to no external forces, and any change which ensues must come from inside. Now the amount of rotational momentum existing in a system in motion can neither be created nor destroyed by any internal causes, and therefore, whatever happens, the amount of rotational momentum possessed by the star must remain absolutely constant. A real star radiates heat, and as it cools it shrinks. Let us suppose then that our ideal star also radiates and shrinks, but let the process proceed so slowly that any internal currents generated in the liquid by the cooling are annulled so quickly by fluid friction as to be insignificant; further let the liquid always remain at any instant incompressible and homogeneous. All that we are concerned with is that, as time passes, the liquid star shrinks, rotates in one piece as if it were solid, and remains incompressible and homogeneous. The condition is of course artificial, but it represents the actual processes of nature as well as may be, consistently with the postulated incompressibility and homogeneity. (Mathematicians are accustomed to regard the density as constant and the rotational momentum as increasing. But the way of looking at the matter, which I have adopted, is easier of comprehension, and it comes to the same in the end.) The shrinkage of a constant mass of matter involves an increase of its density, and we have therefore to trace the changes which supervene as the star shrinks, and as the liquid of which it is composed increases in density. The shrinkage will, in ordinary parlance, bring the weights nearer to the axis of rotation. Hence in order to keep up the rotational momentum, which as we have seen must remain constant, the mass must rotate quicker. The greater speed of rotation augments the importance of centrifugal force compared with that of gravity, and as the flattening of the planetary spheroid was due to centrifugal force, that flattening is increased; in other words the ellipticity of the planetary spheroid increases. As the shrinkage and corresponding increase of density proceed, the planetary spheroid becomes more and more elliptic, and the succession of forms constitutes a family classified according to the density of the liquid. The specific mark of this family is the flattening or ellipticity. Now consider the stability of the system, we have seen that the spheroid with a slow rotation, which forms our starting-point, was slightly less stable than the sphere, and as we proceed through the family of ever flatter ellipsoids the stability continues to diminish. At length when it has assumed the shape shown in a figure titled "Planetary spheroid just becoming unstable" (Fig. 2.) where the equatorial and polar axes are proportional to the numbers 1000 and 583, the stability has just disappeared. According to the general principle explained above this is a form of bifurcation, and corresponds to the form denoted A. The specific difference a of this family must be regarded as the excess of the ellipticity of this figure above that of all the earlier ones, beginning with the slightly flattened planetary spheroid. Accordingly the specific difference a of the family has gradually diminished from the beginning and vanishes at this stage. According to Poincare's principle the vanishing of the stability serves us with notice that we have reached a figure of bifurcation, and it becomes necessary to inquire what is the nature of the specific difference of the new family of figures which must be coalescent with the old one at this stage. This difference is found to reside in the fact that the equator, which in the planetary family has hitherto been circular in section, tends to become elliptic. Hitherto the rotational momentum has been kept up to its constant value partly by greater speed of rotation and partly by a symmetrical bulging of the equator. But now while the speed of rotation still increases (The mathematician familiar with Jacobi's ellipsoid will find that this is correct, although in the usual mode of exposition, alluded to above in a footnote, the speed diminishes.), the equator tends to bulge outwards at two diametrically opposite points and to be flattened midway between these protuberances. The specific difference in the new family, denoted in the general sketch by b, is this ellipticity of the equator. If we had traced the planetary figures with circular equators beyond this stage A, we should have found them to have become unstable, and the stability has been shunted off along the A + b family of forms with elliptic equators. This new series of figures, generally named after the great mathematician Jacobi, is at first only just stable, but as the density increases the stability increases, reaches a maximum and then declines. As this goes on the equator of these Jacobian figures becomes more and more elliptic, so that the shape is considerably elongated in a direction at right angles to the axis of rotation. At length when the longest axis of the three has become about three times as long as the shortest (The three axes of the ellipsoid are then proportional to 1000, 432, 343.), the stability of this family of figures vanishes, and we have reached a new form of bifurcation and must look for a new type of figure along which the stable development will presumably extend. Two sections of this critical Jacobian figure, which is a figure of bifurcation, are shown by the dotted lines in a figure titled "The 'pear-shaped figure' and the Jocobian figure from which it is derived" (Fig. 3.) comprising two figures, one above the other: the upper figure is the equatorial section at right angles to the axis of rotation, the lower figure is a section through the axis. Now Poincare has proved that the new type of figure is to be derived from the figure of bifurcation by causing one of the ends to be prolonged into a snout and by bluntening the other end. The snout forms a sort of stalk, and between the stalk and the axis of rotation the surface is somewhat flattened. These are the characteristics of a pear, and the figure has therefore been called the "pear-shaped figure of equilibrium." The firm line shows this new type of figure, whilst, as already explained, the dotted line shows the form of bifurcation from which it is derived. The specific mark of this new family is the protrusion of the stalk together with the other corresponding smaller differences. If we denote this difference by c, while A + b denotes the Jacobian figure of bifurcation from which it is derived, the new family may be called A + b + c, and c is zero initially. According to my calculations this series of figures is stable (M. Liapounoff contends that for constant density the new series of figures, which M. Poincare discovered, has less rotational momentum than that of the figure of bifurcation. If he is correct, the figure of bifurcation is a limit of stable figures, and none can exist with stability for greater rotational momentum. My own work seems to indicate that the opposite is true, and, notwithstanding M. Liapounoff's deservedly great authority, I venture to state the conclusions in accordance with my own work.), but I do not know at what stage of its development it becomes unstable. Professor Jeans has solved a problem which is of interest as throwing light on the future development of the pear-shaped figure, although it is of a still more ideal character than the one which has been discussed. He imagines an INFINITELY long circular cylinder of liquid to be in rotation about its central axis. The existence is virtually postulated of a demon who is always occupied in keeping the axis of the cylinder straight, so that Jeans has only to concern himself with the stability of the form of the section of the cylinder, which as I have said is a circle with the axis of rotation at the centre. He then supposes the liquid forming the cylinder to shrink in diameter, just as we have done, and finds that the speed of rotation must increase so as to keep up the constancy of the rotational momentum. The circularity of section is at first stable, but as the shrinkage proceeds the stability diminishes and at length vanishes. This stage in the process is a form of bifurcation, and the stability passes over to a new series consisting of cylinders which are elliptic in section. The circular cylinders are exactly analogous with our planetary spheroids, and the elliptic ones with the Jacobian ellipsoids. With further shrinkage the elliptic cylinders become unstable, a new form of bifurcation is reached, and the stability passes over to a series of cylinders whose section is pear-shaped. Thus far the analogy is complete between our problem and Jeans's, and in consequence of the greater simplicity of the conditions, he is able to carry his investigation further. He finds that the stalk end of the pear-like section continues to protrude more and more, and the flattening between it and the axis of rotation becomes a constriction. Finally the neck breaks and a satellite cylinder is born. Jeans's figure for an advanced stage of development is shown in a figure titled "Section of a rotating cylinder of liquid" (Fig. 4.), but his calculations do not enable him actually to draw the state of affairs after the rupture of the neck. There are certain difficulties in admitting the exact parallelism between this problem and ours, and thus the final development of our pear-shaped figure and the end of its stability in a form of bifurcation remain hidden from our view, but the successive changes as far as they have been definitely traced are very suggestive in the study of stellar evolution. Attempts have been made to attack this problem from the other end. If we begin with a liquid satellite revolving about a liquid planet and proceed backwards in time, we must make the two masses expand so that their density will be diminished. Various figures have been drawn exhibiting the shapes of two masses until their surfaces approach close to one another and even until they just coalesce, but the discussion of their stability is not easy. At present it would seem to be impossible to reach coalescence by any series of stable transformations, and if this is so Professor Jeans's investigation has ceased to be truly analogous to our problem at some undetermined stage. However this may be this line of research throws an instructive light on what we may expect to find in the evolution of real stellar systems. In the second part of this paper I shall point out the bearing which this investigation of the evolution of an ideal liquid star may have on the genesis of double stars. II. There are in the heavens many stars which shine with a variable brilliancy. Amongst these there is a class which exhibits special peculiarities; the members of this class are generally known as Algol Variables, because the variability of the star Beta Persei or Algol was the first of such cases to attract the attention of astronomers, and because it is perhaps still the most remarkable of the whole class. But the circumstances which led to this discovery were so extraordinary that it seems worth while to pause a moment before entering on the subject. John Goodricke, a deaf-mute, was born in 1764; he was grandson and heir of Sir John Goodricke of Ribston Hall, Yorkshire. In November 1782, he noted that the brilliancy of Algol waxed and waned (It is said that Georg Palitzch, a farmer of Prohlis near Dresden, had about 1758 already noted the variability of Algol with the naked eye. "Journ. Brit. Astron. Assoc." Vol. XV. (1904-5), page 203.), and devoted himself to observing it on every fine night from the 28th December 1782 to the 12th May 1783. He communicated his observations to the Royal Society, and suggested that the variation in brilliancy was due to periodic eclipses by a dark companion star, a theory now universally accepted as correct. The Royal Society recognised the importance of the discovery by awarding to Goodricke, then only 19 years of age, their highest honour, the Copley medal. His later observations of Beta Lyrae and of Delta Cephei were almost as remarkable as those of Algol, but unfortunately a career of such extraordinary promise was cut short by death, only a fortnight after his election to the Royal Society. ("Dict. of National Biography"; article Goodricke (John). The article is by Miss Agnes Clerke. It is strange that she did not then seem to be aware that he was a deaf-mute, but she notes the fact in her "Problems of Astrophysics", page 337, London, 1903.) It was not until 1889 that Goodricke's theory was verified, when it was proved by Vogel that the star was moving in an orbit, and in such a manner that it was only possible to explain the rise and fall in the luminosity by the partial eclipse of a bright star by a dark companion. The whole mass of the system of Algol is found to be half as great again as that of our sun, yet the two bodies complete their orbit in the short period of 2d 20h 48m 55s. The light remains constant during each period, except for 9h 20m when it exhibits a considerable fall in brightness (Clerke, "Problems of Astrophysics" page 302 and chapter XVIII.); the curve which represents the variation in the light is shown in a figure titled "The light-curve and system of Beta Lyrae" (Fig. 7.). The spectroscope has enabled astronomers to prove that many stars, although apparently single, really consist of two stars circling around one another (If a source of light is approaching with a great velocity the waves of light are crowded together, and conversely they are spaced out when the source is receding. Thus motion in the line of sight virtually produces an infinitesimal change of colour. The position of certain dark lines in the spectrum affords an exceedingly accurate measurement of colour. Thus displacements of these spectral lines enables us to measure the velocity of the source of light towards or away from the observer.); they are known as spectroscopic binaries. Campbell of the Lick Observatory believes that about one star in six is a binary ("Astrophysical Journ." Vol. XIII. page 89, 1901. See also A. Roberts, "Nature", Sept. 12, 1901, page 468.); thus there must be many thousand such stars within the reach of our spectroscopes. The orientation of the planes of the orbits of binary stars appears to be quite arbitrary, and in general the star does not vary in brightness. Amongst all such orbits there must be some whose planes pass nearly through the sun, and in these cases the eclipse of one of the stars by the other becomes inevitable, and in each circuit there will occur two eclipses of unequal intensities. It is easy to see that in the majority of such cases the two components must move very close to one another. The coincidence between the spectroscopic and the photometric evidence permits us to feel complete confidence in the theory of eclipses. When then we find a star with a light-curve of perfect regularity and with a characteristics of that of Algol, we are justified in extending the theory of eclipses to it, although it may be too faint to permit of adequate spectroscopic examination. This extension of the theory secures a considerable multiplication of the examples available for observation, and some 30 have already been discovered. Dr Alexander Roberts, of Lovedale in Cape Colony, truly remarks that the study of Algol variables "brings us to the very threshold of the question of stellar evolution." ("Proc. Roy. Soc. Edinburgh", XXIV. Part II. (1902), page 73.) It is on this account that I propose to explain in some detail the conclusion to which he and some other observers have been led. Although these variable stars are mere points of light, it has been proved by means of the spectroscope that the law of gravitation holds good in the remotest regions of stellar space, and further it seems now to have become possible even to examine the shapes of stars by indirect methods, and thus to begin the study of their evolution. The chain of reasoning which I shall explain must of necessity be open to criticism, yet the explanation of the facts by the theory is so perfect that it is not easy to resist the conviction that we are travelling along the path of truth. The brightness of a star is specified by what is called its "magnitude." The average brightness of all the stars which can just be seen with the naked eye defines the sixth magnitude. A star which only gives two-fifths as much light is said to be of the seventh magnitude; while one which gives 2 1/2 times as much light is of the fifth magnitude, and successive multiplications or divisions by 2 1/2 define the lower or higher magnitudes. Negative magnitudes have clearly to be contemplated; thus Sirius is of magnitude minus 1.4, and the sun is of magnitude minus 26. The definition of magnitude is also extended to fractions; for example, the lights given by two candles which are placed at 100 feet and 100 feet 6 inches from the observer differ in brightness by one-hundredth of a magnitude. A great deal of thought has been devoted to the measurement of the brightness of stars, but I will only describe one of the methods used, that of the great astronomer Argelander. In the neighbourhood of the star under observation some half dozen standard stars are selected of known invariable magnitudes, some being brighter and some fainter than the star to be measured; so that these stars afford a visible scale of brightness. Suppose we number them in order of increasing brightness from 1 to 6; then the observer estimates that on a given night his star falls between stars 2 and 3, on the next night, say between 3 and 4, and then again perhaps it may return to between 2 and 3, and so forth. With practice he learns to evaluate the brightness down to small fractions of a magnitude, even a hundredth part of a magnitude is not quite negligible. For example, in observing the star RR Centauri five stars were in general used for comparison by Dr Roberts, and in course of three months he secured thereby 300 complete observations. When the period of the cycle had been ascertained exactly, these 300 values were reduced to mean values which appertained to certain mean places in the cycle, and a mean light-curve was obtained in this way. Figures titled "Light curve of RR Centauri" (Fig. 5) and "The light-curve and system of Beta Lyrae" (Fig. 7) show examples of light curves. I shall now follow out the results of the observation of RR Centauri not only because it affords the easiest way of explaining these investigations, but also because it is one of the stars which furnishes the most striking results in connection with the object of this essay. (See "Monthly notices R.A.S." Vol. 63, 1903, page 527.) This star has a mean magnitude of about 7 1/2, and it is therefore invisible to the naked eye. Its period of variability is 14h 32m 10s.76, the last refinement of precision being of course only attained in the final stages of reduction. Twenty-nine mean values of the magnitude were determined, and they were nearly equally spaced over the whole cycle of changes. The black dots in Fig. 5 exhibit the mean values determined by Dr Roberts. The last three dots on the extreme right are merely the same as the first three on the extreme left, and are repeated to show how the next cycle would begin. The smooth dotted curve will be explained hereafter, but, by reference to the scale of magnitudes on the margins of the figure, it may be used to note that the dots might be brought into a perfectly smooth curve by shifting some few of the dots by about a hundredth of a magnitude. This light-curve presents those characteristics which are due to successive eclipses, but the exact form of the curve must depend on the nature of the two mutually eclipsing stars. If we are to interpret the curve with all possible completeness, it is necessary to make certain assumptions as to the stars. It is assumed then that the stars are equally bright all over their disks, and secondly that they are not surrounded by an extensive absorptive atmosphere. This last appears to me to be the most dangerous assumption involved in the whole theory. Making these assumptions, however, it is found that if each of the eclipsing stars were spherical it would not be possible to generate such a curve with the closest accuracy. The two stars are certainly close together, and it is obvious that in such a case the tidal forces exercised by each on the other must be such as to elongate the figure of each towards the other. Accordingly it is reasonable to adopt the hypothesis that the system consists of a pair of elongated ellipsoids, with their longest axes pointed towards one another. No supposition is adopted a priori as to the ratio of the two masses, or as to their relative size or brightness, and the orbit may have any degree of eccentricity. These last are all to be determined from the nature of the light-curve. In the case of RR Centauri, however, Dr Roberts finds the conditions are best satisfied by supposing the orbit to be circular, and the sizes and masses of the components to be equal, while their luminosities are to one another in the ratio of 4 to 3. As to their shapes he finds them to be so much elongated that they overlap, as exhibited in his figure titled "The shape of the star RR Centauri" (Fig. 6.). The dotted curve shows a form of equilibrium of rotating liquid as computed by me some years before, and it was added for the sake of comparison. On turning back to Fig. 5 the reader will see in the smooth dotted curve the light variation which would be exhibited by such a binary system as this. The curve is the result of computation and it is impossible not to be struck by the closeness of the coincidence with the series of black dots which denote the observations. It is virtually certain that RR Centauri is a case of an eclipsing binary system, and that the two stars are close together. It is not of course proved that the figures of the stars are ellipsoids, but gravitation must deform them into a pair of elongated bodies, and, on the assumptions that they are not enveloped in an absorptive atmosphere and that they are ellipsoidal, their shapes must be as shown in the figure. This light-curve gives an excellent illustration of what we have reason to believe to be a stage in the evolution of stars, when a single star is proceeding to separate into a binary one. As the star is faint, there is as yet no direct spectroscopic evidence of orbital motion. Let us turn therefore to the case of another star, namely V Puppis, in which such evidence does already exist. I give an account of it, because it presents a peculiarly interesting confirmation of the correctness of the theory. In 1895 Pickering announced in the "Harvard Circular" No. 14 that the spectroscopic observations at Arequipa proved V Puppis to be a double star with a period of 3d 2h 46m. Now when Roberts discussed its light-curve he found that the period was 1d 10h 54m 27s, and on account of this serious discrepancy he effected the reduction only on the simple assumption that the two stars were spherical, and thus obtained a fairly good representation of the light-curve. It appeared that the orbit was circular and that the two spheres were not quite in contact. Obviously if the stars had been assumed to be ellipsoids they would have been found to overlap, as was the case for RR Centauri. ("Astrophysical Journ." Vol. XIII. (1901), page 177.) The matter rested thus for some months until the spectroscopic evidence was re-examined by Miss Cannon on behalf of Professor Pickering, and we find in the notes on page 177 of Vol. XXVIII. of the "Annals of the Harvard Observatory" the following: "A.G.C. 10534. This star, which is the Algol variable V Puppis, has been found to be a spectroscopic binary. The period 1d.454 (i.e. 1d 10h 54m) satisfies the observations of the changes in light, and of the varying separation of the lines of the spectrum. The spectrum has been examined on 61 plates, on 23 of which the lines are double." Thus we have valuable evidence in confirmation of the correctness of the conclusions drawn from the light-curve. In the circumstances, however, I have not thought it worth while to reproduce Dr Roberts's provisional figure. I now turn to the conclusions drawn a few years previously by another observer, where we shall find the component stars not quite in contact. This is the star Beta Lyrae which was observed by Goodricke, Argelander, Belopolsky, Schur, Markwick and by many others. The spectroscopic method has been successfully applied in this case, and the component stars are proved to move in an orbit about one another. In 1897, Mr. G.W. Myers applied the theory of eclipses to the light-curve, on the hypothesis that the stars are elongated ellipsoids, and he obtained the interesting results exhibited in Fig. 7. ("Astrophysical Journ." Vol. VII. (1898), page 1.) The period of Beta Lyrae is relatively long, being 12d 21h 47m, the orbit is sensibly eccentric, and the two spheroids are not so much elongated as was the case with RR Centauri. The mass of the system is enormous, one of the two stars being 10 times and the other 21 times as heavy as our sun. Further illustrations of this subject might be given, but enough has been said to explain the nature of the conclusions which have been drawn from this class of observation. In my account of these remarkable systems the consideration of one very important conclusion has been purposely deferred. Since the light-curve is explicable by eclipses, it follows that the sizes of the two stars are determinable relatively to the distance between them. The period of their orbital motion is known, being identical with the complete period of the variability of their light, and an easy application of Kepler's law of periodic times enables us to compute the sum of the masses of the two stars divided by the cube of the distance between their centres. Now the sizes of the bodies being known, the mean density of the whole system may be calculated. In every case that density has been found to be much less than the sun's, and indeed the average of a number of mean densities which have been determined only amounts to one-eighth of that of the sun. In some cases the density is extremely small, and in no case is it quite so great as half the solar density. It would be absurd to suppose that these stars can be uniform in density throughout, and from all that is known of celestial bodies it is probable that they are gaseous in their external parts with great condensation towards their centres. This conclusion is confirmed by arguments drawn from the theory of rotating masses of liquid. (See J.H. Jeans, "On the density of Algol variables", "Astrophysical Journ." Vol. XXII. (1905), page 97.) Although, as already explained, a good deal is known about the shapes and the stability of figures consisting of homogeneous incompressible liquid in rotation, yet comparatively little has hitherto been discovered about the equilibrium of rotating gaseous stars. The figures calculated for homogeneous liquid can obviously only be taken to afford a general indication of the kind of figure which we might expect to find in the stellar universe. Thus the dotted curve in Fig. 5, which exhibits one of the figures which I calculated, has some interest when placed alongside the figures of the stars in RR Centauri, as computed from the observations, but it must not be accepted as the calculated form of such a system. I have moreover proved more recently that such a figure of homogeneous liquid is unstable. Notwithstanding this instability it does not necessarily follow that the analogous figure for compressible fluid is also unstable, as will be pointed out more fully hereafter. Professor Jeans has discussed in a paper of great ability the difficult problems offered by the conditions of equilibrium and of stability of a spherical nebula. ("Phil. Trans. R.S." Vol. CXCIX. A (1902), page 1. See also A. Roberts, "S. African Assoc. Adv. Sci." Vol. I. (1903), page 6.) In a later paper ("Astrophysical Journ." Vol. XXII. (1905), page 97.), in contrasting the conditions which must govern the fission of a star into two parts when the star is gaseous and compressible with the corresponding conditions in the case of incompressible liquid, he points out that for a gaseous star (the agency which effects the separation will no longer be rotation alone; gravitation also will tend towards separation... From numerical results obtained in the various papers of my own,... I have been led to the conclusion that a gravitational instability of the kind described must be regarded as the primary agent at work in the actual evolution of the universe, Laplace's rotation playing only the secondary part of separating the primary and satellite after the birth of the satellite.) It is desirable to add a word in explanation of the expression "gravitational instability" in this passage. It means that when the concentration of a gaseous nebula (without rotation) has proceeded to a certain stage, the arrangement in spherical layers of equal density becomes unstable, and a form of bifurcation has been reached. For further concentration concentric spherical layers become unstable, and the new stable form involves a concentration about two centres. The first sign of this change is that the spherical layers cease to be quite concentric and then the layers of equal density begin to assume a somewhat pear-shaped form analogous to that which we found to occur under rotation for an incompressible liquid. Accordingly it appears that while a sphere of liquid is stable a sphere of gas may become unstable. Thus the conditions of stability are different in these two simple cases, and it is likely that while certain forms of rotating liquid are unstable the analogous forms for gas may be stable. This furnishes a reason why it is worth while to consider the unstable forms of rotating liquid. There can I think be little doubt but that Jeans is right in looking to gravitational instability as the primary cause of fission, but when we consider that a binary system, with a mass larger than the sun's, is found to rotate in a few hours, there seems reason to look to rotation as a contributory cause scarcely less important than the primary one. With the present extent of our knowledge it is only possible to reconstruct the processes of the evolution of stars by means of inferences drawn from several sources. We have first to rely on the general principles of stability, according to which we are to look for a series of families of forms, each terminating in an unstable form, which itself becomes the starting-point of the next family of stable forms. Secondly we have as a guide the analogy of the successive changes in the evolution of ideal liquid stars; and thirdly we already possess some slender knowledge as to the equilibrium of gaseous stars. From these data it is possible to build up in outline the probable history of binary stars. Originally the star must have been single, it must have been widely diffused, and must have been endowed with a slow rotation. In this condition the strata of equal density must have been of the planetary form. As it cooled and contracted the symmetry round the axis of rotation must have become unstable, through the effects of gravitation, assisted perhaps by the increasing speed of rotation. (I learn from Professor Jeans that he now (December 1908) believes that he can prove that some small amount of rotation is necessary to induce instability in the symmetrical arrangement.) The strata of equal density must then become somewhat pear-shaped, and afterwards like an hour-glass, with the constriction more pronounced in the internal than in the external strata. The constrictions of the successive strata then begin to rupture from the inside progressively outwards, and when at length all are ruptured we have the twin stars portrayed by Roberts and by others. As we have seen, the study of the forms of equilibrium of rotating liquid is almost complete, and Jeans has made a good beginning in the investigation of the equilibrium of gaseous stars, but much more remains to be discovered. The field for the mathematician is a wide one, and in proportion as the very arduous exploration of that field is attained so will our knowledge of the processes of cosmical evolution increase. From the point of view of observation, improved methods in the use of the spectroscope and increase of accuracy in photometry will certainly lead to a great increase in our knowledge within the next few years. Probably the observational advance will be more rapid than that of theory, for we know how extraordinary has been the success attained within the last few years, and the theory is one of extreme difficulty; but the two ought to proceed together hand in hand. Human life is too short to permit us to watch the leisurely procedure of cosmical evolution, but the celestial museum contains so many exhibits that it may become possible, by the aid of theory, to piece together bit by bit the processes through which stars pass in the course of their evolution. In the sketch which I have endeavoured to give of this fascinating subject, I have led my reader to the very confines of our present knowledge. It is not much more than a quarter of a century since this class of observation has claimed the close attention of astronomers; something considerable has been discovered already and there seems scarcely a discernible limit to what will be known in this field a century from now. Some of the results which I have set forth may then be shown to be false, but it seems profoundly improbable that we are being led astray by a Will-of-the-Wisp. XXIX. THE EVOLUTION OF MATTER. By W.C.D. Whetham, M.A., F.R.S. Trinity College, Cambridge. The idea of evolution in the organic world, made intelligible by the work of Charles Darwin, has little in common with the recent conception of change in certain types of matter. The discovery that a process of disintegration may take place in some at least of the chemical atoms, previously believed to be indestructible and unalterable, has modified our view of the physical universe, even as Darwin's scheme of the mode of evolution changed the trend of thought concerning the organic world. Both conceptions have in common the idea of change throughout extended realms of space and time, and, therefore, it is perhaps not unfitting that some account of the most recent physical discoveries should be included in the present volume. The earliest conception of the evolution of matter is found in the speculation of the Greeks. Leucippus and Democritus imagined unchanging eternal atoms, Heracleitus held that all things were in a continual state of flux--Panta rei. But no one in the Ancient World--no one till quite modern times--could appreciate the strength of the position which the theory of the evolution of matter must carry before it wins the day. Vague speculation, even by the acute minds of philosophers, is of little use in physical science before experimental facts are available. The true problems at issue cannot even be formulated, much less solved, till the humble task of the observer and experimenter has given us a knowledge of the phenomena to be explained. It was only through the atomic theory, at first apparently diametrically opposed to it, that the conception of evolution in the physical world was to gain an established place. For a century the atomic theory, when put into a modern form by Dalton, led farther and farther away from the idea of change in matter. The chemical elements seemed quite unalterable, and the atoms, of which each element in modern view is composed, bore to Clerk Maxwell, writing about 1870, "the stamp of manufactured articles" exactly similar in kind, unchanging, eternal. Nevertheless throughout these years, on the whole so unfavourable to its existence, there persisted the idea of a common origin of the distinct kinds of matter known to chemists. Indeed, this idea of unity in substance in nature seems to accord with some innate desire or intimate structure of the human mind. As Mr Arthur Balfour well puts it, "There is no a priori reason that I know of for expecting that the material world should be a modification of a single medium, rather than a composite structure built out of sixty or seventy elementary substances, eternal and eternally different. Why then should we feel content with the first hypothesis and not with the second? Yet so it is. Men of science have always been restive under the multiplication of entities. They have eagerly watched for any sign that the different chemical elements own a common origin, and are all compounded out of some primordial substance. Nor, for my part, do I think that such instincts should be ignored... that they exist is certain; that they modify the indifferent impartiality of pure empiricism can hardly be denied." ("Report of the 74th Meeting of the British Association" (Presidential Address, Cambridge 1904), page 9, London, 1905.) When Dalton's atomic theory had been in existence some half century, it was noted that certain numerical relations held good between the atomic weights of elements chemically similar to one another. Thus the weight (88) of an atom of strontium compared with that of hydrogen as unity, is about the mean of those of calcium (40) and barium (137). Such relations, in this and other chemical groups, were illustrated by Beguyer de Chancourtois in 1862 by the construction of a spiral diagram in which the atomic weights are placed in order round a cylinder and elements chemically similar are found to fall on vertical lines. Newlands seems to have been the first to see the significance of such a diagram. In his "law of octaves," formulated in 1864, he advanced the hypothesis that, if arranged in order of rising atomic weight, the elements fell into groups, so that each eighth element was chemically similar. Stated thus, the law was too definite; no room was left for newly-discovered elements, and some dissimilar elements were perforce grouped together. But in 1869 Mendeleeff developed Newland's hypothesis in a form that attracted at once general attention. Placing the elements in order of rising atomic weight, but leaving a gap where necessary to bring similar elements into vertical columns, he obtained a periodic table with natural vacancies to be filled as new elements were discovered, and with a certain amount of flexibility at the ends of the horizontal lines. From the position of the vacancies, the general chemical and physical properties of undiscovered elements could be predicted, and the success of such predictions gave a striking proof of the usefulness of Mendeleeff's generalisation. When the chemical and physical properties of the elements were known to be periodic functions of their atomic weights, the idea of a common origin and common substance became much more credible. Differences in atomic weight and differences in properties alike might reasonably be explained by the differences in the amount of the primordial substance present in the various atoms; an atom of oxygen being supposed to be composed of sixteen times as much stuff as the atom of hydrogen, but to be made of the same ultimate material. Speculations about the mode of origin of the elements now began to appear, and put on a certain air of reality. Of these speculations perhaps the most detailed was that of Crookes, who imagined an initial chaos of a primordial medium he named protyle, and a process of periodic change in which the chemical elements successively were precipitated. From another side too, suggestions were put forward by Sir Norman Lockyer and others that the differences in spectra observed in different classes of stars, and produced by different conditions in the laboratory, were to be explained by changes in the structure of the vibrating atoms. The next step in advance gave a theoretical basis for the idea of a common structure of matter, and was taken in an unexpected direction. Clerk Maxwell's electromagnetic theory of light, accepted in England, was driven home to continental minds by the confirmatory experiments of Hertz, who in 1888 detected and measured the electromagnetic waves that Maxwell had described twenty years earlier. But, if light be an electromagnetic phenomenon, the light waves radiated by hot bodies must take their origin in the vibrations of electric systems. Hence within the atoms must exist electric charges capable of vibration. On these lines Lorentz and Larmor have developed an electronic theory of matter, which is imagined in its essence to be a conglomerate of electric charges, with electro-magnetic inertia to explain mechanical inertia. (Larmor, "Aether and Matter", Cambridge, 1900.) The movement of electric charges would be affected by a magnetic field, and hence the discovery by Zeeman that the spectral lines of sodium were doubled by a strong magnetic force gave confirmatory evidence to the theory of electrons. Then came J.J. Thomson's great discovery of minute particles, much smaller than any chemical atom, forming a common constituent of many different kinds of matter. (Thomson, "Conduction of Electricity through Gases" (2nd edition), Cambridge, 1906.) If an electric discharge be passed between metallic terminals through a glass vessel containing air at very low pressure, it is found that rectilinear rays, known as cathode rays, proceed from the surface of the cathode or negative terminal. Where these rays strike solid objects, they give rise to the Rontgen rays now so well known; but it is with the cathode rays themselves that we are concerned. When they strike an insulated conductor, they impart to it a negative charge, and Thomson found that they were deflected from their path both by magnetic and electric forces in the direction in which negatively electrified particles would be deflected. Cathode rays then were accepted as flights of negatively charged particles, moving with high velocities. The electric and magnetic deflections give two independent measurements which may be made on a cathode ray, and both the deflections involve theoretically three unknown quantities, the mass of the particles, their electric charge and their velocity. There is strong cumulative evidence that all such particles possess the same charge, which is identical with that associated with a univalent atom in electrolytic liquids. The number of unknown quantities was thus reduced to two--the mass and the velocity. The measurement of the magnetic and electric deflections gave two independent relations between the unknowns, which could therefore be determined. The velocities of the cathode ray particles were found to vary round a value about one-tenth that of light, but the mass was found always to be the same within the limits of error, whatever the nature of the terminals, of the residual gas in the vessel, and of the conditions of the experiment. The mass of a cathode ray particle, or corpuscle, as Thomson, adopting Newton's name, called it, is about the eight-hundredth part of the mass of a hydrogen atom. These corpuscles, found in so many different kinds of substance, are inevitably regarded as a common constituent of matter. They are associated each with a unit of negative electricity. Now electricity in motion possesses electromagnetic energy, and produces effects like those of mechanical inertia. In other words, an electric charge possesses mass, and there is evidence to show that the effective mass of a corpuscle increases as its velocity approaches that of light in the way it would do if all its mass were electromagnetic. We are led therefore to regard the corpuscle from one aspect as a disembodied charge of electricity, and to identify it with the electron of Lorentz and Larmor. Thus, on this theory, matter and electricity are identified; and a great simplification of our conception of the physical structure of Nature is reached. Moreover, from our present point of view, a common basis for matter suggests or implies a common origin, and a process of development possibly intelligible to our minds. The idea of the evolution of matter becomes much more probable. The question of the nature and physical meaning of a corpuscle or electron remains for consideration. On the hypothesis of a universal luminiferous aether, Larmor has suggested a centre of aethereal strain "a place where the continuity of the medium has been broken and cemented together again (to use a crude but effective image) without accurately fitting the parts, so that there is a residual strain all round the place." (Larmor, loc. cit.) Thus he explains in quasi-mechanical terms the properties of an electron. But whether we remain content for the time with our identification of matter and electricity, or attempt to express both of them in terms of hypothetical aether, we have made a great step in advance on the view that matter is made up of chemical atoms fundamentally distinct and eternally isolated. Such was the position when the phenomena of radio-activity threw a new light on the problem, and, for the first time in the history of science, gave definite experimental evidence of the transmutation of matter from one chemical element to another. In 1896 H. Becquerel discovered that compounds of the metal uranium continually emitted rays capable of penetrating opaque screens and affecting photographic plates. Like cathode and Rontgen rays, the rays from uranium make the air through which they pass a conductor of electricity, and this property gives the most convenient method of detecting the rays and of measuring their intensity. An electroscope may be made of a strip of gold-leaf attached to an insulated brass plate and confined in a brass vessel with glass windows. When the gold-leaf is electrified, it is repelled from the similarly electrified brass plate, and the angle at which it stands out measures the electrification. Such a system, if well insulated, holds its charge for hours, the leakage of electricity through the air being very slow. But, if radio-active radiation reach the air within, the gold-leaf falls, and the rate of its fall, as watched through a microscope with a scale in the eye-piece, measures the intensity of the radiation. With some form of this simple instrument, or with the more complicated quadrant electrometer, most radio-active measurements have been made. It was soon discovered that the activity of uranium compounds was proportional to the amount of uranium present in them. Thus radio-activity is an atomic property dependent on the amount of an element and independent of its state of chemical combination. In a search for radio-activity in different minerals, M. and Mme Curie found a greater effect in pitch-blende than its contents of uranium warranted, and, led by the radio-active property alone, they succeeded, by a long series of chemical separations, in isolating compounds of a new and intensely radio-active substance which they named radium. Radium resembles barium in its chemical properties, and is precipitated with barium in the ordinary course of chemical analysis. It is separated by a prolonged course of successive crystallisation, the chloride of radium being less soluble than that of barium, and therefore sooner separated from an evaporating solution. When isolated, radium chloride has a composition, which, on the assumption that one atom of metal combines with two of chlorine as in barium chloride, indicates that the relative weight of the atom of radium is about 225. As thus prepared, radium is a well-marked chemical element, forming a series of compounds analogous to those of barium and showing a characteristic line spectrum. But, unlike most other chemical elements, it is intensely radio-active, and produces effects some two million times greater than those of uranium. In 1899 E. Rutherford, then of Montreal, discovered that the radiation from uranium, thorium and radium was complex. (Rutherford, "Radio-activity" (2nd edition), Cambridge, 1905.) Three types of rays were soon distinguished. The first, named by Rutherford alpha-rays, are absorbed by thin metal foil or a few centimetres of air. When examined by measurements of the deflections caused by magnetic and electric fields, the alpha-rays are found to behave as would positively electrified particles of the magnitude of helium atoms possessing a double ionic charge and travelling with a velocity about one-tenth that of light. The second or beta type of radiation is much more penetrating. It will pass through a considerable thickness of metallic foil, or many centimetres of air, and still affect photographic plates or discharge electroscopes. Magnetic and electric forces deflect beta-rays much more than alpha-rays, indicating that, although the speed is greater, approaching in some cases within five per cent. that of light, the mass is very much less. The beta-rays must be streams of particles, identical with those of cathode rays, possessing the minute mass of J.J. Thomson's corpuscle, some eight-hundredth part of that of a hydrogen atom. A third or gamma type of radiation was also detected. More penetrating even than beta-rays, the gamma-rays have never been deflected by any magnetic or electric force yet applied. Like Rontgen rays, it is probable that gamma-rays are wave-pulses in the luminiferous aether, though the possibility of explaining them as flights of non-electrified particles is before the minds of some physicists. Still another kind of radiation has been discovered more recently by Thomson, who has found that in high vacua, rays become apparent which are absorbed at once by air at any ordinary pressure. The emission of all these different types of radiation involves a continual drain of energy from the radio-active body. When M. and Mme Curie had prepared as much as a gramme of radium chloride, the energy of the radiation became apparent as an evolution of heat. The radium salt itself, and the case containing it, absorbed the major part of the radiation, and were thus maintained at a temperature measurably higher than that of the surroundings. The rate of thermal evolution was such that it appeared that one gramme of pure radium must emit about 100 gramme-calories of heat in an hour. This observation, naturally as it follows from the phenomena previously discovered, first called attention to the question of the source of the energy which maintains indefinitely and without apparent diminution the wonderful stream of radiation proceeding from a radio-active substance. In the solution of this problem lies the point of the present essay. In order to appreciate the evidence which bears on the question we must now describe two other series of phenomena. It is a remarkable fact that the intensity of the radiation from a radio-active body is independent of the external conditions of temperature, pressure, etc. which modify so profoundly almost all other physical and chemical processes. Exposure to the extreme cold of liquid air, or to the great heat of a furnace, leaves the radio-activity of a substance unchanged, apparent exceptions to this statement having been traced to secondary causes. Then, it is found that radio-activity is always accompanied by some chemical change; a new substance always appears as the parent substance emits these radiations. Thus by chemical reactions it is possible to separate from uranium and thorium minute quantities of radio-active materials to which the names of uranium-X and thorium-X have been given. These bodies behave differently from their parents uranium and thorium, and show all the signs of distinct chemical individuality. They are strongly radio-active, while, after the separation, the parents uranium and thorium are found to have lost some of their radio-activity. If the X-substances be kept, their radio-activity decays, while that of the uranium or thorium from which they were obtained gradually rises to the initial value it had before the separation. At any moment, the sum of the radio-activity is constant, the activity lost by the product being equal to that gained by the parent substance. These phenomena are explained if we suppose that the X-product is slowly produced in the substance of the parent, and decays at a constant rate. Uranium, as usually seen, contains a certain amount of uranium-X, and its radio-activity consists of two parts--that of the uranium itself, and that of the X product. When the latter is separated by means of its chemical reactions, its radio-activity is separated also, and the rates of decay and recovery may be examined. Radium and thorium, but not uranium, give rise to radio-active gases which have been called emanations. Rutherford has shown that their radio-activity, like that of the X products, suffers decay, while the walls of the vessel in which the emanation is confined, become themselves radio-active. If washed with certain acids, however, the walls lose their activity, which is transferred to the acid, and can be deposited by evaporation from it on to a solid surface. Here again it is clear that the emanation gives rise to a radio-active substance which clings to the walls of the vessel, and is soluble in certain liquids, but not in others. We shall return to this point, and trace farther the history of the radio-active matter. At present we wish to emphasise the fact that, as in other cases, the radio-activity of the emanation is accompanied by the appearance of a new kind of substance with distinct chemical properties. We are now in a position to consider as a whole the evidence on the question of the source of radio-active energy. (1) Radio-activity is accompanied by the appearance of new chemical substances. The energy liberated is therefore probably due to the associated chemical change. (2) The activity of a series of compounds is found to accompany the presence of a radio-active element, the activity of each compound depends only on the contents of the element, and is independent of the nature of its combination. Thus radio-activity is a property of the element, and is not affected by its state of isolation or chemical combination. (3) The radio-activity of a simple transient product decays in a geometrical progression, the loss per second being proportional to the mass of substance still left at the moment, and independent of its state of concentration or dilution. This type of reaction is well known in chemistry to mark a mono-molecular change, where each molecule is dissociated or altered in structure independently. If two or more molecules were concerned simultaneously, the rate of reaction would depend on the nearness of the molecules to each other, that is, to the concentration of the material. (4) The amount of energy liberated by the change of a given mass of material far transcends the amount set free by any known ordinary chemical action. The activity of radium decays so slowly that it would not sink to half its initial value in less than some two thousand years, and yet one gramme of radium emits about 100 calories of heat during each hour of its existence. The energy of radio-activity is due to chemical change, but clearly to no chemical change hitherto familiar to science. It is an atomic property, characteristic of a given element, and the atoms undergo the change individually, not by means of interaction among each other. The conclusion is irresistible that we are dealing with a fundamental change in the structure of the individual atoms, which, one by one, are dissociating into simpler parts. We are watching the disintegration of the "atoms" of the chemist, hitherto believed indestructible and eternal, and measuring the liberation of some of the long-suspected store of internal atomic energy. We have stumbled on the transmutation dreamed by the alchemist, and discovered the process of a veritable evolution of matter. The transmutation theory of radio-activity was formulated by Rutherford (Rutherford, "Radio-activity" (2nd edition), Cambridge, 1905, page 307.) and Soddy in 1903. By its light, all recent work on the subject has been guided; it has stood the supreme test of a hypothesis, and shown power to suggest new investigations and to co-ordinate and explain them, when carried out. We have summarised the evidence which led to the conception of the theory; we have now to consider the progress which has been made in tracing the successive disintegration of radio-active atoms. Soon after the statement of the transmutation theory, a striking verification of one of its consequences appeared. The measurement of the magnetic and electric deflection of the alpha-rays suggested to Rutherford the idea that the stream of projectiles of which they consisted was a flight of helium atoms. Ramsay and Soddy, confining a minute bubble of radium emanation in a fine glass tube, were able to watch the development of the helium spectrum as, day by day, the emanation decayed. By isolating a very narrow pencil of alpha-rays, and watching through a microscope their impact on a fluorescent screen, Rutherford has lately counted the individual alpha-projectiles, and confirmed his original conclusion that their mass corresponded to that of helium atoms and their charge to double that on a univalent atom. ("Proc. Roy. Soc." A, page 141, 1908.) Still more recently, he has collected the alpha-particles shot through an extremely thin wall of glass, and demonstrated by direct spectroscopic evidence the presence of helium. ("Phil. Mag." February 1909.) But the most thorough investigation of a radio-active pedigree is found in Rutherford's classical researches on the successive disintegration products of radium, in order to follow the evidence on which his results are founded, we must describe more fully the process of decay of the activity of a simple radio-active substance. The decay of activity of the body known as uranium-X is shown in a falling curve (Fig. 1.). It will be seen that, in each successive 22 days, the activity falls to half the value it possessed at the beginning. This change in a geometrical progression is characteristic of simple radio-active processes, and can be expressed mathematically by a simple exponential formula. As we have said above, solid bodies exposed to the emanations of radium or thorium become coated with a radio-active deposit. The rate of decay of this activity depends on the time of exposure to the emanation, and does not always show the usual simple type of curve. Thus the activity of a rod exposed to radium emanation for 1 minute decays in accordance with a curve (Fig. 2) which represents the activity as measured by the alpha-rays. If the electroscope be screened from the alpha-rays, it is found that the activity of the rod in beta- an gamma-rays increases for some 35 minutes and then diminishes (Fig. 3.). These complicated relations have been explained satisfactorily and completely by Rutherford on the hypothesis of successive changes of the radio-active matter into one new body after another. (Rutherford, "Radio-activity" (2nd edition), Cambridge, 1905, page 379.) The experimental curve represents the resultant activity of all the matter present at a given moment, and the process of disentangling the component effects consists in finding a number of curves, which express the rise and fall of activity of each kind of matter as it is produced and decays, and, fitted together, give the curve of the experiments. Other methods of investigation also are open. They have enabled Rutherford to complete the life-history of radium and its products, and to clear up doubtful points left by the analysis of the curves. By the removal of the emanation, the activity of radium itself has been shown to consist solely of alpha-rays. This removal can be effected by passing air through the solution of a radium salt. The emanation comes away, and the activity of the deposit which it leaves behind decays rapidly to a small fraction of its initial value. Again, some of the active deposits of the emanation are more volatile than others, and can be separated from them by the agency of heat. From such evidence Rutherford has traced a long series of disintegration products of radium, all but the first of which exist in much too minute quantities to be detected otherwise than by their radio-activities. Moreover, two of these products are not themselves appreciably radio-active, though they are born from radio-active parents, and give rise to a series of radio-active descendants. Their presence is inferred from such evidence as the rise of beta and gamma radio-activity in the solid newly deposited by the emanation; this rise measuring the growth of the first radio-active offspring of one of the non-active bodies. Some of the radium products give out alpha-rays only, one beta- and gamma-rays, while one yields all three types of radiation. The pedigree of the radium family may be expressed in the following table, the time noted in the second column being the time required for a given quantity to be half transformed into its next derivative. Time of half Radio- Properties decay activity Radium About 2600 years alpha rays Element chemically analogous to barium. Emanation 3.8 days alpha rays Chemically inert gas; condenses at -150 deg C. Radium-A 3 minutes alpha rays Behaves as a solid deposited on surfaces; concentrated on a negative electrode. Radium-B 21 minutes no rays Soluble in strong acids; volatile at a white heat; more volatile than A or C. Radium-C 28 minutes alpha, beta, Soluble in strong acids; less gamma rays volatile than B. Radium-D about 40 years no rays Soluble in strong acids; volatile below 1000 deg C. Radium-E 6 days beta, gamma Non-volatile at 1000 deg C. rays Radium-F 143 days alpha rays Volatile at 1000 deg C. Deposited from solution on a bismuth plate. Of these products, A, B, and C constitute that part of the active deposit of the emanation which suffers rapid decay and nearly disappears in a few hours. Radium-D, continually producing its short-lived descendants E and F, remains for years on surfaces once exposed to the emanation, and makes delicate radio-active researches impossible in laboratories which have been contaminated by an escape of radium emanation. A somewhat similar pedigree has been made out in the case of thorium. Here thorium-X is interposed between thorium and its short-lived emanation, which decays to half its initial quantity in 54 seconds. Two active deposits, thorium A and B, arise successively from the emanation. In uranium, we have the one obvious derivative uranium-X, and the question remains whether this one descent can be connected with any other individual or family. Uranium is long-lived, and emits only alpha-rays. Uranium-X decays to half value in 22 days, giving out beta- and gamma-rays. Since our evidence goes to show that radio-activity is generally accompanied by the production of new elements, it is natural to search for the substance of uranium-X in other forms, and perhaps under other names, rather than to surrender immediately our belief in the conservation of matter. With this idea in mind we see at once the significance of the constitution of uranium minerals. Formed in the remote antiquity of past geological ages, these minerals must become store-houses of all the products of uranium except those which may have escaped as gases or possibly liquids. Even gases may be expected to some extent to be retained by occlusion. Among the contents of uranium minerals, then, we may look for the descendants of the parent uranium. If the descendants are permanent or more long-lived than uranium, they will accumulate continually. If they are short-lived, they will accumulate at a steady rate till enough is formed for the quantity disintegrating to be equal to the quantity developed. A state of mobile equilibrium will then be reached, and the amount of the product will remain constant. This constant amount of substance will depend only on the amount of uranium which is its source, and, for different minerals, if all the product is retained, the quantity of the product will be proportional to the quantity of uranium. In a series of analyses of uranium minerals, therefore, we ought to be able to pick out its more short-lived descendants by seeking for instances of such proportionality. Now radium itself is a constituent of uranium minerals, and two series of experiments by R.J. Strutt and B.B. Boltwood have shown that the content of radium, as measured by the radio-activity of the emanation, is directly proportional to the content of uranium. (Strutt, "Proc. Roy. Soc." A, February 1905; Boltwood, "Phil. Mag." April, 1905.) In Boltwood's investigation, some twenty minerals, with amounts of uranium varying from that in a specimen of uraninite with 74.65 per cent., to that in a monazite with 0.30 per cent., gave a ratio of uranium to radium, constant within about one part in ten. The conclusion is irresistible that radium is a descendant of uranium, though whether uranium is its parent or a more remote ancestor requires further investigation by the radio-active genealogist. On the hypothesis of direct parentage, it is easy to calculate that the amount of radium produced in a month by a kilogramme of a uranium salt would be enough to be detected easily by the radio-activity of its emanation. The investigation has been attempted by several observers, and the results, especially those of a careful experiment of Boltwood, show that from purified uranium salts the growth of radium, if appreciable at all, is much less than would be found if the radium was the first product of change of the uranium. It is necessary, therefore, to look for one or more intermediate substances. While working in 1899 with the uranium residues used by M. and Mme Curie for the preparation of radium, Debierne discovered and partially separated another radio-active element which he called actinium. It gives rise to an intermediate product actinium-X, which yields an emanation with the short half-life of 3.9 seconds. The emanation deposits two successive disintegration products actinium-A and actinium-B. Evidence gradually accumulated that the amounts of actinium in radio-active minerals were, roughly at any rate, proportional to the amounts of uranium. This result pointed to a lineal connection between them, and led Boltwood to undertake a direct attack on the problem. Separating a quantity of actinium from a kilogramme of ore, Boltwood observed a growth of 8.5 x (10 to the power -9) gramme of radium in 193 days, agreeing with that indicated by theory within the limits of experimental error. ("American Journal of Science", December, 1906.) We may therefore insert provisionally actinium and its series of derivatives between uranium and radium in the radio-active pedigree. Turning to the other end of the radium series we are led to ask what becomes of radium-F when in turn it disintegrates? What is the final non-active product of the series of changes we have traced from uranium through actinium and radium? One such product has been indicated above. The alpha-ray particles appear to possess the mass of helium atoms, and the growth of helium has been detected by its spectrum in a tube of radium emanation. Moreover, helium is found occluded in most if not all radio-active minerals in amount which approaches, but never exceeds, the quantity suggested by theory. We may safely regard such helium as formed by the accumulation of alpha-ray particles given out by successive radio-active changes. In considering the nature of the residue left after the expulsion of the five alpha-particles, and the consequent passage of radium to radium-F we are faced by the fact that lead is a general constituent of uranium minerals. Five alpha-particles, each of atomic weight 4, taken from the atomic weight (about 225) of radium gives 205--a number agreeing fairly well with the 207 of lead. Since lead is more permanent than uranium, it must steadily accumulate, no radio-active equilibrium will be reached, and the amount of lead will depend on the age of the mineral as well as on the quantity of uranium present in it. In primary minerals from the same locality, Boltwood has shown that the contents of lead are proportional to the amounts of uranium, while, accepting this theory, the age of minerals with a given content of uranium may be calculated from the amount of lead they contain. The results vary from 400 to 2000 million years. ("American Journal of Science", October, 1905, and February, 1907.) We can now exhibit in tabular form the amazing pedigree of radio-active change shown by this one family of elements. An immediate descent is indicated by >, while one which may either be immediate or involve an intermediate step is shown by.... No place is found in this pedigree for thorium and its derivatives. They seem to form a separate and independent radio-active family. Atomic Weight Time of half Radio-Activity decay Uranium 238.5 alpha Uranium-X ? 22 days beta, gamma ... Actinium ? ? no rays Actinium-X ? 10.2 days alpha (beta, gamma) Actinium Emanation ? 3.9 seconds alpha Actinium-A ? 35.7 minutes no rays Actinium-B ? 2.15 minutes alpha, beta, gamma ... Radium 225 about 2600 years alpha Radium Emanation ? 3.8 days alpha Radium-A ? 3 minutes alpha Radium-B ? 21 minutes no rays Radium-C ? 28 minutes alpha, beta, gamma Radium-D ? about 40 years no rays Radium-E ? 6 days beta (gamma) Radium-F ? 143 days alpha ... Lead 207 ? no rays As soon as the transmutation theory of radio-activity was accepted, it became natural to speculate about the intimate structure of the radio-active atoms, and the mode in which they broke up with the liberation of some of their store of internal energy. How could we imagine an atomic structure which would persist unchanged for long periods of time, and yet eventually spontaneously explode, as here an atom and there an atom reached a condition of instability? The atomic theory of corpuscles or electrons fortunately was ready to be applied to this new problem. Of the resulting speculations the most detailed and suggestive is that of J.J. Thomson. ("Phil. Mag." March, 1904.) Thomson regards the atom as composed of a number of mutually repelling negative corpuscles or electrons held together by some central attractive force which he represents by supposing them immersed in a uniform sphere of positive electricity. Under the action of the two forces, the electrons space themselves in symmetrical patterns, which depend on the number of electrons. Three place themselves at the corner of an equilateral triangle, four at those of a square, and five form a pentagon. With six, however, the single ring becomes unstable, one corpuscle moves to the middle and five lie round it. But if we imagine the system rapidly to rotate, the centrifugal force would enable the six corpuscles to remain in a single ring. Thus internal kinetic energy would maintain a configuration which would become unstable as the energy drained away. Now in a system of electrons, electromagnetic radiation would result in a loss of energy, and at one point of instability we might well have a sudden spontaneous redistribution of the constituents, taking place with an explosive violence, and accompanied by the ejection of a corpuscle as a beta-ray, or of a large fragment of the atom as an alpha-ray. The discovery of the new property of radio-activity in a small number of chemical elements led physicists to ask whether the property might not be found in other elements, though in a much less striking form. Are ordinary materials slightly radio-active? Does the feeble electric conductivity always observed in the air contained within the walls of an electroscope depend on ionizing radiations from the material of the walls themselves? The question is very difficult, owing to the wide distribution of slight traces of radium. Contact with radium emanation results in a deposit of the fatal radium-D, which in 40 years is but half removed. Is the "natural" leak of a brass electroscope due to an intrinsic radio-activity of brass, or to traces of a radio-active impurity on its surface? Long and laborious researches have succeeded in establishing the existence of slight intrinsic radio-activity in a few metals such as potassium, and have left the wider problem still unsolved. It should be noted, however, that, even if ordinary elements are not radio-active, they may still be undergoing spontaneous disintegration. The detection of ray-less changes by Rutherford, when those changes are interposed between two radio-active transformations which can be followed, show that spontaneous transmutation is possible without measureable radio-activity. And, indeed, any theory of disintegration, such as Thomson's corpuscular hypothesis, would suggest that atomic rearrangements are of much more general occurrence than would be apparent to one who could observe them only by the effect of the projectiles, which, in special cases, owing to some peculiarity of atomic configuration, happened to be shot out with the enormous velocity needed to ionize the surrounding gas. No evidence for such ray-less changes in ordinary elements is yet known, perhaps none may ever be obtained; but the possibility should not be forgotten. In the strict sense of the word, the process of atomic disintegration revealed to us by the new science of radio-activity can hardly be called evolution. In each case radio-active change involves the breaking up of a heavier, more complex atom into lighter and simpler fragments. Are we to regard this process as characteristic of the tendencies in accord with which the universe has reached its present state, and is passing to its unknown future? Or have we chanced upon an eddy in a backwater, opposed to the main stream of advance? In the chaos from which the present universe developed, was matter composed of large highly complex atoms, which have formed the simpler elements by radio-active or ray-less disintegration? Or did the primaeval substance consist of isolated electrons, which have slowly come together to form the elements, and yet have left here and there an anomaly such as that illustrated by the unstable family of uranium and radium, or by some such course are returning to their state of primaeval simplicity? INDEX. Abraxas grossulariata. Acquired characters, transmission of. Acraea johnstoni. Adaptation. Adloff. Adlumia cirrhosa. Agassiz, A. Agassiz, L. Alexander. Allen, C.A. Alternation of generations. Ameghino. Ammon, O., Works of. Ammonites, Descent of. Amphidesmus analis. Anaea divina. Andrews, C.W. Angiosperms, evolution of. Anglicus, Bartholomaeus. Ankyroderma. Anomma. Antedon rosacea. Antennularia antennina. Anthropops. Ants, modifications of. Arber, E.A.N.,--and J. Parkin, on the origin of Angiosperms. Archaeopteryx. Arctic regions, velocity of development of life in. Ardigo. Argelander. Argyll, Huxley and the Duke of. Aristotle. Arrhenius. Asterias, Loeb on hybridisation of. Autogamy. Avena fatua. Avenarius. Bacon, on mutability of species. Baehr, von, on Cytology. Baer, law of von. Bain. Baldwin, J.M. Balfour, A.J. Ball, J. Barber, Mrs M.E., on Papilio nireus. Barclay, W. Barratt. Bary, de. Bates, H.W., on Mimicry.--Letters from Darwin to.--elsewhere. Bateson, A. BATESON, W., on "Heredity and Variation in Modern lights".--on discontinuous evolution.--on hybridisation. Bateson, W. and R.P. Gregory. Bathmism. Beche, de la. Beck, P. Becquerel, H. Beebe, C.W., on the plumage of birds.--on sexual selection. Beguyer de Chancourtois. Bell's (Sir Charles) "Anatomy of Expression". Belopolsky. Belt, T., on Mimicry. Beneden, E. van. Benson, M. Bentham, G., on Darwin's species-theory.--on geographical distribution. Bentham, Jeremy. Bergson, H. Berkeley. Berthelot. Betham, Sir W. Bickford, E., experiments on degeneration by. Bignonia capreolata. Biophores. Birds, geological history of. Blanford, W.T. Blaringhem, on wounding. Blumenbach. Bodin. Boltwood, B.B. Bonald, on war. Bonnet. Bonney, T.G. Bonnier, G. Bopp, F., on language. BOUGLE C., on "Darwinism and Sociology". Bourdeau. Bourget, P. Boutroux. Boveri, T. Brachiopods, history of. Brassica, hybrids of. Brassica Napus. Broca. Brock, on Kant. Brown, Robert. Brugmann and Osthoff. Brugmann. Brunetiere. Bruno, on Evolution. Buch, von. Bucher, K. Buckland. Buckle. Buffon. Burchell, W.J. Burck, W. Burdon-Sanderson, J., letter from. BURY, J.B., on "Darwinism and History". Butler, A.G. Butler, Samuel. Butschli, O. Butterflies, mimicry in.--sexual characters in. Cabanis. Campbell. Camels, geological history of. Camerarius, R.J. Candolle, A. de. Cannon and Davenport, experiments on Daphniae by. Capsella bursapastoris. Carneri. Castnia linus. Catasetum barbatum. Catasetum tridentatum. Caterpillars, variation in. Celosia, variability of. Cereals, variability in. Cesnola, experiments on Mantis by. Chaerocampa, colouring of. Chambers, R., "The Vestiges of Creation" by. Chromosomes and Chromomeres. Chun. Cieslar, experiments by. Circumnutation, Darwin on. Claus. Cleistogamy. Clerke, Miss A. Clodd, E. Cluer. Clytus arietis. Coadaptation. Codrington. Cohen and Peter. Collingwood. Colobopsis truncata. Colour, E.B. Poulton on The Value in the Struggle for life of.--influence and temperature on changes in.--in relation to Sexual Selection. Colours, incidental.--warning. Comte, A. Condorcet. Cope. Coral reefs, Darwin's work on. Correlation of organisms, Darwin's idea of the. Correlation of parts. Corydalis claviculata. Cournot. Couteur, Col. Le. Crooks, Sir William. Cruger, on Orchids. Cunningham and Marchand, on the brain. Curie, M. and Mme. Cuvier. Cycadeoidea dacotensis. Cycads, geological history of. Cystidea, an ancient group. Cytology and heredity. Cytolysis and fertilisation. Czapek. Dalton's atomic theory. Dana, J.D., on marine faunas. Danaida chrysippus. Danaida genutia. Danaida plexippus. Dante. Dantec, Le, Darwin, Charles, as an Anthropologist.--on ants.--and the "Beagle" Voyage.--on the Biology of Flowers.--as a Botanist.--his influence on Botany.--and S. Butler.--at Cambridge.--on Cirripedia.--on climbing plants.--on colour.--on coral reefs.--on the Descent of Man.--his work on Drosera.--at Edinburgh.--his influence on Animal Embryology.--on Geographical Distribution.--his work on Earthworms.--evolutionist authors referred to in the "Origin" by.--and E. Forbes.--on the geological record.--and Geology.--his early love for geology.--his connection with the Geological Society of London.--and Haeckel.--and Henslow.--and History.--and Hooker.--and Huxley.--on ice-action.--on igneous rocks.--on Lamarck.--on Language.--his Scientific Library.--and the Linnean Society.--and Lyell.--and Malthus.--on Patrick Matthew.--on mental evolution.--on Mimicry.--a "Monistic Philosopher."--on the movements of plants.--on Natural Selection.--a "Naturalist for Naturalists."--on Paley. Darwin, Charles, his Pangenesis hypothesis.--on the permanence of continents.--his personality.--his influence on Philosophy.--predecessors of.--his views on religion, etc.--his influence on religious thought.--his influence on the study of religions.--his methods of research.--and Sedgwick.--on Sexual Selection.--the first germ of his species theory.--on H. Spencer.--causes of his success.--on Variation.--on the "Vestiges of Creation".--on volcanic islands.--and Wallace.--letter to Wallace from.--letter to E.B. Wilson from. Darwin, E., on the colour of animals.--Charles Darwin's reference to.--on evolution. DARWIN, F., on "Darwin's work on the Movements of Plants".--on Darwin as a botanist.--observations on Earthworms by.--on Lamarckism.--on Memory.--on Prichard's "Anticipations".--various. DARWIN, SIR G., on "The Genesis of Double Stars".--on the earth's mass. Darwin, H. Darwin, W. Darwinism, Sociology, Evolution and. Davenport and Cannon, experiments on Daphniae by. David, T.E., his work on Funafuti. Death, cause of natural. Debey, on Cretaceous plants. Debierne. Degeneration. Delage, experiments on parthenogenesis by. Delbruck. Democritus. Deniker. Descartes. Descent, history of doctrine of. "Descent of Man", G. Schwalbe on "The".--Darwin on Sexual Selection in "The".--rejection in Germany of "The". Desmatippus. Desmoulins, A., on Geographical Distribution. Detto. Development, effect of environment on. Dianthus caryophyllus. Diderot. Digitalis purpurea. Dimorphism, seasonal. Dismorphia astynome. Dismorphia orise. Distribution, H. Gadow on Geographical.--Sir W. Thiselton-Dyer on. Dittrick, O. Dixey, F.A., on the scent of Butterflies. Dolichonyx oryzivorus. Dorfmeister. Down, Darwin at. Draba verna. Dragomirov. Driesch, experiments by.--elsewhere. Drosera, Darwin's work on. Dryopithecus. Dubois, E., on Pithecanthropus. Duhring. Duhamel. Duncan, J.S. Duncan, P.B. Duns Scotus. Duret, C. Durkheim, on division of labour. Dutrochet. Echinoderms, ancestry of. Ecology. Eimer. Ekstam. Elephants, geological history of. Elymnias phegea. E. undularis. Embleton, A.L. Embryology, A. Sedgwick on the influence of Darwin on. Embryology, as a clue to Phylogeny.--the Origin of Species and. Empedocles. Engles. Environment, action of.--Klebs on the influence on plants of.--Loeb on experimental study in relation to. Eohippus. Epicurus, a poet of Evolution. Eristalis. Ernst. Ernst, A., on the Flora of Krakatau. Eschscholzia californica. Espinas. Eudendrium racemosum. Evolution, in relation to Astronomy.--and creation.--conception of.--discontinuous.--experimental.--factors of.--fossil plants as evidence of.--and language.--of matter, W.C.D. Whetham on.--mental.--Lloyd Morgan on mental factors in.--Darwinism and Social.--Saltatory.--Herbert Spencer on.--Uniformitarian.--Philosophers and modern methods of studying. Expression of the Emotions. Fabricius, J.C., on geographical distribution. Farmer, J.B. Farrer, Lord. Fearnsides, W.G. Felton, S., on protective resemblance. Ferri. Ferrier, his work on the brain. Fertilisation, experimental work on animal-. Fertilisation of Flowers. Fichte. Field, Admiral A.M. Fischer, experiments on Butterflies by. Fitting. Flemming, W. Flourens. Flowering plants, ancestry of. Flowers, K. Goebel on the Biology of. Flowers and Insects. Flowers, relation of external influences to the production of. Fol, H. Forbes, E.--and C. Darwin. Ford, S.O. and A.C. Seward, on the Araucarieae. Fossil Animals, W.B. Scott on their bearing on evolution. Fossil Plants, D.H. Scott on their bearing on evolution. Fouillee. Fraipont, on skulls from Spy. FRAZER, J.G., on "Some Primitive Theories of the Origin of Man".--various. Fruwirth. Fumaria officinalis. Funafuti, coral atoll of. Fundulus. F. heteroclitus. GADOW, H., on "Geographical Distribution of Animals".--elsewhere. Gartner, K.F. Gallus bankiva. Galton, F. Gamble, F.W. and F.W. Keeble. Gasca, La. Geddes, P. Geddes, P. and A.W. Thomson. Gegenbauer. Geikie, Sir A. Geitonogamy. Genetics. Geographical Distribution of Animals.--of Plants.--influence of "The Origin of Species" on.--Wallace's contribution to. Geography of former periods, reconstruction of. Geology, Darwin and. Geranium spinosum. Germ-plasm, continuity of.--Weismann on. Germinal Selection. Gibbon. Gilbert. GILES, P., on "Evolution and the Science of Language". Giuffrida-Ruggeri. Giotto. Gizycki. Glossopteris Flora. Gmelin. Godlewski, on hybridisation. GOEBEL, K., on "The Biology of Flowers".--his work on Morphology. Goethe and Evolution.--on the relation between Man and Mammals.--elsewhere. Goldfarb. Gondwana Land. Goodricke, J. Gore, Dr. Gorjanovic-Kramberger. Gosse, P.H. Grabau, A.W., on Fusus. Grand'Eury, F.C., on fossil plants. Grapta C. album. Gravitation, effect on life-phenomena of. Gray, Asa. Gregoire, V. Groom, T.T., on heliotropism. Groos. Grunbaum, on the brain. Guignard, L. Gulick. Guppy, on plant-distribution. Guyau. Gwynne-Vaughan, D.T., on Osmundaceae. Gymnadenia conopsea. Haberlandt, G. Haddon, A.C. HAECKEL, E., on "Charles Darwin as an Anthropologist".--on Colour.--and Darwin.--on the Descent of Man.--contributions to Evolution by. Haeckel, E., on Lamarck.--on Language.--a leader in the Darwinian controversy.--on Lyell's influence on Darwin.--various. Hacker. Hagedoorn, on hybridisation. Hales, S. Hansen. Harker, A. HARRISON, J.E., on "The Influence of Darwinism on the Study of Religions". Hartmann, von. Harvey. Haupt, P., on Language. Haycraft. Hays, W.M. Hegel. Heliconius narcaea. Heliotropism in animals. Henslow, Rev. J.S. and Darwin. Hensen, Van. Herbst, his experiments on sea urchins. Heracleitus. Herder. Heredity and Cytology.--Haeckel on.--and Variation.--various. Hering, E., on Memory. Herschel, J. Hertwig, R. Hertwig, O. Hertz. Heteromorphosis. Heterostylism. Heuser, E. Hewitt. Heyse's theory of language. Hinde, G.J., his work on Funafuti. Hipparion. Hippolyte cranchii. Hirase. History, Darwin and. Hobbes, T. Hobhouse. HOFFDING, H., on "The Influence of the Conception of Evolution on Modern Philosophy". Hofmeister, W. Holmes, S.J., on Arthropods. Holothurians, calcareous bodies in skin of. Homo heidelbergensis. Homo neandertalensis. Homo pampaeus. Homo primigenius. Homunculus. Hooker, Sir J.D., and Darwin.--on Distribution of Plants.--on Ferns.--Letter to the Editor from. Horner, L. Horse, Geological history of the. Huber. Hubert and Mauss. Hubrecht, A.R.W. Hugel, F. von. Humboldt, A. von. Humboldt, W. von. Hume. Hutcheson. Hutton. Huxley, T.H., and Darwin.--and the Duke of Argyll.--on Embryology.--on Geographical Distribution.--on Lamarck.--Letter to J.W. Judd from.--on Lyell.--on Man.--on "The Origin of Species".--on Selection.--on Teleology.--on transmission of acquired characters.--various. Hybridisation. Hybrids, Sterility of. Hyracodon. Iberis umbellata. Ikeno. Imperfection of the Geological Record. Ingenhousz, on plant physiology. Inheritance of acquired characters. Insects and Flowers. Instinct. Instincts, experimental control of animal. Ipomaea purpurea. Irish Elk, an example of co-adaptation. Jacobian figures. Jacoby, "Studies in Selection" by. James, W. Janczewski. Jeans, J.H. Jennings, H.S., on Paramoecium. Jentsch. Jespersen, Prof., Theory of. Johannsen, on Species. Jones, Sir William, on Language. Jordan. JUDD, J.W., on "Darwin and Geology". Kallima, protective colouring of. Kallima inachis. Kammerer's experiments on Salamanders. Kant, I. Keane, on the Primates. Keeble, F.W. and F.W. Gamble, on Colour-change. Keith, on Anthropoid Apes. Kellogg, V., on heliotropism. Kepler. Kerguelen Island. Kidd. Kidston, R., on fossil plants. Killmann, on origin of human races. King, Sir George. Klaatsch, on Ancestry of Man. Klaatsch and Hauser. KLEBS, G., on "The influence of Environment on the forms of plants". Kniep. Knies. Knight, A., experiments on plants by.--on Geotropism. Knight-Darwin law. Knuth. Kolliker, his views on Evolution. Kolreuter, J.G. Kohl. Korschinsky. Kowalevsky, on fossil horses. Krakatau, Ernst on the Flora of. Krause, E. Kreft, Dr. Kropotkin. Kupelwieser, on hybridisation. Lagopus hyperboreus. Lamarck, his division of the Animal Kingdom.--Darwin's opinion of.--on Evolution.--on Man.--various. Lamarckian principle. Lamb, C. Lamettrie. Lamprecht. Lanessan, J.L. de. Lang. Lange. Language, Darwin on.--Evolution and the Science of.--various. Lankester, Sir E. Ray, on degeneration.--on educability.--on the germ-plasm theory.--elsewhere. Lapouge, Vacher de. Larmor, J. Lartet, M.E. Lassalle. Lathyrus odoratus. Lavelaye, de. Lawrence, W. Lehmann. Lehmann-Nitsche. Leibnitz. Lepidium Draba. Lepidoptera, variation in. Leskien, A., on language. Lessing. Leucippus. Levi, E. Lewes, G.H. Lewin, Capt. Liapounoff. Liddon, H.P. Light, effect on organisms of. Limenitis archippus.--arthemis. Linnaeus. Livingstone, on plant-forms. Llamas, geological history of. Lockyer, Sir N. Locy, W.A. LOEB, J., on "The Experimental Study of the influence of environment on Animals. Loew, E. Longstaff, G.B., on the Scents of Butterflies. Lorentz. Lotsy, J.P. Love, A.E.W. Lovejoy. Lubbock. Lucas, K. Lucretius, a poet of Evolution. Lumholtz, C. Luteva macrophthalma. Lycorea halia. Lyell, Sir Charles, and Darwin.--the influence of.--on geographical distribution.--on "The Origin of Species".--on the permanence of Ocean-basins.--publication of the "Principles" by.--the uniformitarian teaching of. Lythrum salicaria. Macacus, ear of. MacDougal, on wounding. Mach, E. Macromytis flexuosa, colour-change in. Magic and religion. Mahoudeau. Maillet, de. Majewski. Malthus, his influence on Darwin.--various. Mammalia, history of. Man, Descent of.--J.G. Frazer on some primitive theories of the origin of.--mental and moral qualities of animals and.--pre-Darwinian views on the Descent of.--religious views of primitive.--Tertiary flints worked by. "Man", G. Schwalbe on Darwin's "Descent of". Manouvrier. Mantis religiosa, colour experiments on. Marett, R.R. Markwick. Marshall, G.A.K. Marx. Massart. Masters, M. Matonia pectinata. Matthew, P., and Natural Selection. Maupertuis. Maurandia semperflorens. Mauss and Herbert. Mauthner. Maxwell. Maxwell, Clerk. Mayer, R. Mechanitis lysimnia. Meehan, T. Meldola, R., Letters from Darwin to. Melinaea ethra. Mendel. Mendeleeff. Merrifield. Merz, J.T. Mesembryanthemum truncatum. Mesohippus. Mesopithecus. Metschnikoff. Mill, J.S. Mimicry.--H.W. Bates on.--F. Muller on. Mimulus luteus. Miquel, F.W.A. Mobius. Mohl, H. von. Moltke, on war. Monachanthus viridis. Monkeys, fossil. Montesquieu. Montgomery, T.H. Monstrosoties. Monticelli. Moore, J.E.S. MORGAN, C. LLOYD, on "Mental Factors in Evolution".--on Organic Selection. Morgan, T.H. Morse, E.S., on colour. Morselli. Mortillet. Moseley. Mottier, M. Muller, Fritz, "Fur Darwin" by.--on Mimicry. Muller, Fritz. Muller, J. Muller, Max, on language. Murray, A., on geographical distribution. Murray, G. Mutability. Mutation. Myanthus barbatus. Myers, G.W., on Eclipses. Nageli. Nathorst, A.G. Nathusius. Natural Selection, and adaptation.--Darwin's views on.--Darwin and Wallace on.--and design.--and educability.--Fossil plants in relation to.--and human development.--and Mimicry.--and Mutability.--various. Naudin. Neandertal skulls. Nemec. Neoclytus curvatus. Neodarwinism. Neumayr, M. Newton, A. Newton, I. Niebuhr. Nietzsche. Nilsson, on cereals. Nitsche. Noire. Noll. Novicow. Nuclear division. Nussbaum, M. Nuttall, G.H.F. Occam. Odin. Oecology, see Ecology. Oenothera biennis. Oenothera gigas. Oenothera Lamarckiana. Oenothera muricata. Oenothera nanella. Oestergren, on Holothurians. Oken, L. Oliver, F.W., on Palaeozoic Seeds. Ononis minutissima. Ophyrs apifera. Orchids, Darwin's work on the fertilisation of. Organic Selection. "Origin of Species", first draft of the.--geological chapter in the. Orthogenesis. Ortmann, A.E. Osborn, H.F.--"From the Greeks to Darwin" by. Osthoff and Brugmann. Ostwald, W. Ovibos moschatus. Owen, Sir Richard. Oxford, Ashmolean Museum at. Packard, A.S. Palaeontological Record, D.H. Scott on the.--W.B. Scott on the. Palaeopithecus. Paley. Palitzch, G. Palm. Pangenesis. Panmixia, Weismann's principle of. Papilio dardanus. Papilio meriones. Papilio merope. Papilio nireus. Paramoecium, Jennings on. Parker, G.H., on Butterflies. Parkin, J. and E.A.N. Arber, on the origin of Angiosperms. Parthenogenesis, artificial. Paul, H. and Wundt. Pearson, K. Peckham, Dr and Mrs, on the Attidae. Penck. Penzig. Peripatus, distribution of. Peridineae. Permanence of continents. Perrier, E. Perrhybris pyrrha. Perthes, B. de. Peter, on sea urchin's eggs. Petunia violacea. Pfeffer, W. Pfitzner, W. Pflueger. Phillips. Philosophy, influence of the conception of evolution on modern. Phryniscus nigricans. Phylogeny, embryology as a clue to.--Palaeontological evidence on. Physiology of plants, development of. Piccard, on Geotropism. Pickering, spectroscopic observations by. Piranga erythromelas. Pisum sativum. Pithecanthropus. Pitheculites. Planema epaea. Plants, Darwin's work on the movements of.--geographical distribution of.--Palaeontological record of fossil. Platanthera bifolia. Plate. Plato. Playfair. Pliopithecus. Pocock, R.I. Poincare. Polarity, Vochting on. Polymorphic species.--variability in cereals. Polypodium incanum. Porthesia chrysorrhoea. Potonie, R. Pouchet, G. POULTON, E.B., on "The Value of Colour in the Struggle for Life".--experiments on Butterflies by.--on J.C. Prichard.--on Mimicry.--various. Pratt. Pratz, du. Premutation. Preuss, K. Th. Prichard, J.C. Primula, heterostylism in. Primula acaulis. Primula elatior. Primula officinalis. Promeces viridis. Pronuba yuccasella. Protective resemblance. Protocetus. Protohippus. Psychology. Pteridophytes, history of. Pteridospermeae. Pucheran. Pusey. Quatrefages, A. de. Quetelet, statistical investigations by. Rabl, C. Radio-activity. Radiolarians. Raimannia odorata. Ramsay, Sir W. and Soddy. Ranke. Rau, A. Ray, J. Reade, Mellard. Recapitulation, the theory of. Reduction. Regeneration. Reid, C. Reinke. Religion, Darwin's attitude towards.--Darwin's influence on the study of.--and Magic. Religious thought, Darwin's influence on. Renard, on Darwin's work on volcanic islands. Reproduction, effect of environment on. Reptiles, history of. Reversion. Rhinoceros, the history of the. Ridley, H.N. Riley, C.V. Ritchie. Ritual. Roberts, A. Robertson, T.B. Robinet. Rolfe, R.A. Rolph. Romanes, G.J. Rothert. Roux. Rozwadowski, von. Ruskin. Rutherford, E. Rutot. Sachs, J. St Hilaire, E.G. de. Salamandra atra. Salamandra maculosa. Saltatory Evolution, (see also Mutations). Sanders, experiments on Vanessa by. Saporta, on the Evolution of Angiosperms. Sargant, Ethel, on the Evolution of Angiosperms. Savigny. Scardafella inca. Scent, in relation to Sexual Selection. Scharff, R.F. Schelling. Schlegel. Schleicher, A., on language. Schleiden and Schwann, Cell-theory of. Schmarda, L.K., on geographical distribution. Schoetensack, on Homo heidelbergensis. Schreiner, K.E. Schubler, on cereals. Schultze, O., experiments on Frogs. Schur. Schutt. SCHWALBE, G., on "The Descent of Man". Sclater, P.L., on geographical distribution. SCOTT, D.H., on "The Palaeontological Record (Plants)".--elsewhere. SCOTT, W.B., on "The Palaeontological Record (Animals)". Scrope. Scyllaea. Sechehaye, C.A. SEDGWICK, A., on "The Influence of Darwin on Animal Embryology". Sedgwick, A., Darwin's Geological Expedition with. Seeck, O. Seed-plants, origin of. Segregation. Selection, artificial.--germinal. Selection, natural (see Natural Selection).--organic.--sexual.--social and natural.--various. Selenka. Semnopithecus. Semon, R. Semper. Senebier. Senecio vulgaris. Sergi. Seward, A.C.--and S.O. Ford.--and J. Gowan. Sex, recent investigations on. Sharpe, D. Sherrington, C.S. Shirreff, P. Shrewsbury, Darwin's recollections of. Sibbern. Sinapis alba. Smerinthus ocellata. Smerinthus populi. Smerinthus tiliae. Smith, A. Smith, W. Snyder. Sociology, Darwinism and.--History and. Soddy. Sollas, W.J. Sorley, W.R. Species, Darwin's early work on transmutation of.--geographical distribution and origin of.--immutability of.--influence on environment on.--Lamarck on.--multiple origin of.--the nature of a.--polymorphic.--production by physico-chemical means of.--and varieties.--de Vries's work on. Spencer, H., on evolution.--on Lyell's "Principles".--on the nature of the living cell.--on primitive man.--on the theory of Selection.--on Sociology. Spencer, H., on the transmission of acquired characters.--on Weismann.--various. Sphingidae, variation in. Spinoza. Sports. Sprengel, C.K. Stability, principle of. Stahl. Standfuss. Stars, evolution of double. Stellaria media. Stephen, L. Sterility in hybrids. Sterne, C. Stockard, his experiments on fish embryos. STRASBURBER, E., on "The Minute Structure of Cells in relation to Heredity". Strongylocentrotus franciscanus. Strongylocentrotus purpuratus. Struggle for existence. Strutt, R.J. Stuart, A. Sturdee, F.C.D. Sutterlin, L. Sully. Sutton, A.W. Sutton, W.S. Svalof, agricultural station of. Swainson, W. Synapta, calcareous bodies in skin of. S. lappa. Syrphus. Tarde, G. Teleology and adaptation. Tennant, F.R. Teratology. Tetraprothomo. THISELTON-DYER, SIR WILLIAM, on "Geographical distribution of Plants".--on Burchell.--on protective resemblance.--elsewhere. THOMSON, J.A., on "Darwin's Predecessors.--elsewhere.--and P. Geddes. Thomson, Sir J.J. Theology, Darwin and. Tiedemann, F. Tooke, Horne. Totemism. Treschow. Treviranus. Trifolium pratense quinquefolium. Trigonias. Trilobites, phylogeny of. Tschermack. Turgot. Turner, Sir W. Twins, artificial production of. Tylor. Tyndall, W. Tyrrell, G. Uhlenhuth, on blood reactions. Underhill, E. Use and disuse. Vanessa. Vanessa antiope. Vanessa levana. Vanessa polychloros. Vanessa urticae. Van 't Hoff. Varanus Salvator. Variability, Darwin's attention directed to.--W. Bateson on.--and cultivation.--causes of.--polymorphic. Variation, continuous and discontinuous.--Darwin's views as an evolutionist, and as a systematist, on.--definite and indefinite.--environment and.--and heredity.--as seen in the life-history of an organism.--minute.--mutability and.--in relation to species.--H. de Vries on. Varigny, H. de. Varro, on language. Veronica chamaedrys. Verworn. "Vestiges of Creation", Darwin on "The". Vierkandt. Vilmorin, L. de. Virchow, his opposition to Darwin. Virchow, on the transmission of acquired characters. Vochting. Vogt, C. Voltaire. Volvox. VRIES, H. de, on "Variation"--the Mutation theory of. WAGGETT, REV. P.N., on "The Influence of Darwin upon religious thought". Wagner. Waldeyer, W. Wallace, A.R., on Malayan Butterflies.--on Colour.--and Darwin.--on the Descent of Man.--on distribution.--on Malthus.--on Natural Selection.--on the permanence of continents.--on social reforms.--on Sexual Selection. Waller, A.D. Walton. Watson, H.C. Watson, S. Watt, J., and Natural Selection. Watts, W.W. Wedgwood, L. Weir, J.J. WEISMANN, A., on "The Selection Theory".--on Amphimixis. Weismann, A., his germ-plasm theory.--on ontogeny.--and Prichard.--and Spencer.--on the transmission of acquired characters.--various. Wells, W.C., and Natural Selection. Weston, S., on language. WHETHAM, W.C.D., on "The Evolution of Matter". Whewell. White, G. Wichmann. Wieland, G.R., on fossil Cycads. Wiesner, on Darwin's work on plant movements. Williams, C.M. Williamson, W.C. Wilson, E.B., on cytology.--letter from Darwin to. Wolf. Wollaston's, T.V. "Variation of Species". Woltmann. Woolner. Wundt, on language. Xylina vetusta. Yucca, fertilisation of. Zeiller, R., on Fossil Plants. Zeller, E. Zimmermann, E.A.W. Zittel, on palaeontological research. "Zoonomia", Erasmus Darwin's. 
29739	----	LITTLE MASTERPIECES OF SCIENCE [Illustration: Charles R. Darwin.] Little Masterpieces of Science Edited by George Iles THE NATURALIST AS INTERPRETER AND SEER _By_ Charles Darwin Alfred R. Wallace Thomas H. Huxley Leland O. Howard George Iles NEW YORK DOUBLEDAY, PAGE & COMPANY 1902 Copyright, 1902, by Doubleday, Page & Co. Copyright, 1877, by D. Appleton & Co. Copyright, 1901, by John Wanamaker Copyright, 1895, by G. H. Buek & Co. TRANSCRIBER'S NOTES: Obvious printer's errors have been silently corrected. Hyphenated and accented words have been standardized. See the end of this file for more information. PREFACE To gather stones and fallen boughs is soon to ask, what may be done with them, can they be piled and fastened together for shelter? So begins architecture, with the hut as its first step, with the Alhambra, St. Peter's, the capitol at Washington, as its last. In like fashion the amassing of fact suggests the ordering of fact: when observation is sufficiently full and varied it comes to the reasons for what it sees. The geologist delves from layer to layer of the earth beneath his tread, he finds as he compares their fossils that the more recent forms of life stand highest in the scale of being, that in the main the animals and plants of one era are more allied to those immediately next than to those of remoter times. He thus divines that he is but exploring the proofs of lineal descent, and with this thought in his mind he finds that the collections not only of his own district, but of every other, take on a new meaning. The great seers of science do not await every jot and tittle of evidence in such a case as this. They discern the drift of a fact here, a disclosure there, and with both wisdom and boldness assume that what they see is but a promise of what shall duly be revealed. Thus it was that Darwin early in his studies became convinced of the truth of organic evolution: the labours of a lifetime of all but superhuman effort, a judicial faculty never exceeded among men, served only to confirm his confidence that all the varied forms of life upon earth have come to be what they are through an intelligible process, mainly by "natural selection." The present volume offers from the classic pages of Darwin his summary of the argument of "The Origin of Species," his account of how that book came to be written, and his recapitulation of "The Descent of Man." All this affords a supreme lesson as to the value of observation with a purpose. When Darwin was confronted with an organ or trait which puzzled him, he was wont to ask, What use can it have had? And always the answer was that every new peculiarity of plant, or beast, is seized upon and held whenever it confers advantage in the unceasing conflict for place and food. No hue of scale or plume, no curve of beak or note of song, but has served a purpose in the plot of life, or advanced the action in a drama where the penalty for failure is extinction. As Charles Darwin stood first among the naturalists of the nineteenth century, his advocacy of evolution soon wrought conviction among the thinkers competent to follow his evidence and weigh his arguments. The opposition to his theories though short was sharp, and here he found a lieutenant of unflinching courage, of the highest expository power, in Professor Huxley. This great teacher came to America in 1876, and discoursed on the ancestry of the horse, as disclosed in fossils then recently discovered in the Far West, maintaining that they afforded unimpeachable proof of organic evolution. His principal lecture is here given. In a remarkable field of "natural selection" Bates, Wallace and Poulton have explained the value of "mimicry" as an aid to beasts, birds, insects, as they elude their enemies or lie unsuspected on the watch for prey. The resemblances thus worked out through successive generations attest the astonishing plasticity of bodily forms, a plasticity which would be incredible were not its evidence under our eyes in every quarter of the globe. Insects have high economic importance as agents of destruction: we are learning how to pit one of them against another, so as to leave a clear field to the farmer and the fruit grower. In this department a leader is Professor Howard, who contributes a noteworthy chapter on the successful fight against the pest which threatened with ruin the orange groves of California. To the every-day observer the most enticing field of natural history is that in which common flowers and common insects work out their unending co-partnery. A blossom by its scent, its beauty of tint, allures a moth or bee and thus, in effect, is able to take flight and find a mate across a county so as to perpetuate its race a hundred miles from home. Our volume closes with a sketch of the singular ties which thus bind together the fortunes of blossom and insect, so that at last the very form of a flower may be cast in the mould of its winged ally. A word is also spoken regarding the singular relations of late detected between the world of vegetation and minute forms once deemed parasitic. The pea and its kindred harbor on their rootlets certain tiny lodgers; the tenants pay a liberal rent in the form of nitrogen compounds, a striking interlacement of interests! GEORGE ILES. CONTENTS DARWIN, CHARLES THE ORIGIN OF SPECIES IN SUMMARY Varieties merge gradually into species. Animals tend to increase in geometrical ratio. Varieties diverge in consonance with diversity of opportunity for life. In the struggle for existence those which best accord with their surroundings will survive and propagate their kind. Sexual selection has put a premium on beauty. The causes which in brief periods produce varieties, in long periods give rise to species. Instincts, as of the hive bee, are slowly developed. Geology supports the theory of Evolution: the changes in time in the fossil record are gradual. Geographical distribution lends its corroboration: in each region most of the inhabitants in every great class are plainly related. A common ancestor is suggested when we see the similarity of hand, wing and fin. Embryos of birds, reptiles and fish are closely similar and unlike adult forms. Slight changes in the course of millions of years produce wide divergences. 3 DARWIN, CHARLES HOW "THE ORIGIN OF SPECIES" CAME TO BE WRITTEN During his voyage on the _Beagle_ Darwin saw fossil armadillos like existing species, and on the islands of the Galapagos group a gradually increased diversity of species of every kind. All this suggested that species gradually become modified. Notes gathered of facts bearing on the question. Observes that it is the variation between one animal and another which gives the breeder his opportunity. Reads Malthus on Population, a work which points out the keen struggle for existence and that favourable variations tend to be preserved. In 1842 draws up a brief abstract of the theory of "natural selection." In 1856 begins an elaborate work on the same theme, but in 1858, hearing that Wallace has written an essay advancing an independent theory of natural selection, offers a summary of his argument to the Linnean Society of London. Writes "The Origin of Species," which is published most successfully, November, 1859. 35 DARWIN, CHARLES THE DESCENT OF MAN: THE ARGUMENT IN BRIEF Since evolution is probable for all other animals, it is probable for man. The human form has so much in common with the forms of other animals that community of descent is strongly suggested. Man, like other creatures, is subject to the struggle for existence. Evidence shows that it is likely that man is descended from a tailed and hairy quadruped that dwelt in trees. Man's mental power has been the chief factor in his advance, especially in his development of language. Conscience is due to social instincts, love of approbation, memory, imagination and religious feeling. Sexual selection in its effects upon human advancement. 45 WALLACE, ALFRED R. MIMICRY AND OTHER PROTECTIVE RESEMBLANCES AMONG ANIMALS The colours of animals are useful for concealment from their prey, from the creatures upon which they prey. The lion is scarcely visible as he crouches on the sand or among desert rocks and stones. Larks, quails and many other birds are so tinted and mottled that their detection is difficult. The polar bear, living amid ice and snow, is white. Reptiles and fish are so coloured as to be almost invisible in the grass or gravel where they rest. Many beetles and other insects are so like the leaves or bark on which they feed that when motionless they cannot be discerned. Some butterflies resemble dead, dry or decaying leaves so closely as to elude discovery. Every individual better protected by colour than others, has a better chance for life, and of transmitting his hues. Harmless beetles and flies are so like wasps and bees as to be left alone. 71 HUXLEY, THOMAS H. EVOLUTION OF THE HORSE The hoof of the horse is simply a greatly enlarged and thickened nail: four of his five toes are reduced to mere vestiges. His teeth are built of substances of varying hardness: they wear away at different rates presenting uneven grinding surfaces. Probable descent of the horse, link by link, especially as traced in the fossils of North America. Evolution has taken a long time: how long the physicist and the astronomer must decide. 101 HOWARD, LELAND O. FIGHTING PESTS WITH INSECT ALLIES A scale insect threatened with ruin the orchards of California. Professor C. V. Riley decided that the pest was a native of Australia. Mr. A. Hoebele observes in Australia that the pest is kept down by ladybirds. These are accordingly sent to California where they destroy the scale insect and restore prosperity among the fruit-growers. Another pest, of olive trees, is devoured by an imported ladybird of another species. This plan extended to Portugal and Egypt with success. Grasshoppers killed by a fungus cultivated for the purpose. Introduction into the United States of the insect which fertilizes the Smyrna fig. 123 ILES, GEORGE THE STRANGE STORY OF THE FLOWERS: A CHAPTER IN MODERN BOTANY Dress is important, whether natural or artificial. Because they catch dust on their clothes, bees, moths and butterflies have brought about myriad espousals of flower with flower. Colours and scents of blossoms attract insects. A flower which in form, scent or hue varies gainfully is likely to survive while others perish. All the parts of a flower are leaves in disguise. Floral modes of repulsion and defence. Plants which devour insects, a habit gradually acquired. The mesquit tree tells of water. Plants believed to indicate mineral veins. Seeds as emigrants equipped with wings or hooks. Parasitic plants and their degradation. Tenants that pay a liberal rent. The gardener as a creator of new flowers. The modern sugar beet due to Mons. Vilmorin. 139 THE NATURALIST AS INTERPRETER AND SEER THE ORIGIN OF SPECIES: THE ARGUMENT IN SUMMARY CHARLES DARWIN [Charles Darwin, one of the greatest men of all time, did more to advance and prove the theory of evolution than anybody else who ever lived. This he accomplished by virtue of the highest gifts of observation, experiment, and generalization. His truthfulness, patience, and calmness of judgment have never been exceeded by mortal. His works are published by D. Appleton & Co., New York, together with his "Life and Letters," edited by his son Francis. From "The Origin of Species" the argument in summary is here given.] On the view that species are only strongly marked and permanent varieties, and that each species first existed as a variety, we can see why it is that no line of demarcation can be drawn between species, commonly supposed to have been produced by special acts of creation, and varieties which are acknowledged to have been produced by secondary laws. On this same view we can understand how it is that in a region where many species of a genus have been produced, and where they now flourish, these same species should present many varieties; for where the manufactory of species has been active, we might expect, as a general rule, to find it still in action; and this is the case if varieties be incipient species. Moreover, the species of the larger genera, which afford the greater number of varieties or incipient species, retain to a certain degree the character of varieties; for they differ from each other by a less amount of difference than do the species of smaller genera. The closely allied species also of a larger genera apparently have restricted ranges, and in their affinities they are clustered in little groups round other species--in both respects resembling varieties. These are strange relations on the view that each species was independently created, but are intelligible if each existed first as a variety. As each species tends by its geometrical rate of reproduction to increase inordinately in number; and as the modified descendants of each species will be enabled to increase by as much as they become more diversified in habits and structure, so as to be able to seize on many and widely different places in the economy of nature, there will be a constant tendency in natural selection to preserve the most divergent offspring of any one species. Hence, during a long-continued course of modification, the slight differences of characteristic of varieties of the same species, tend to be augmented into the greater differences characteristic of the species of the same genus. New and improved varieties will inevitably supplant and exterminate the older, less improved, and intermediate varieties; and thus species are rendered to a large extent defined and distinct objects. Dominant species belonging to the larger groups within each class tend to give birth to new and dominant forms; so that each large group tends to become still larger, and at the same time more divergent in character. But as all groups cannot thus go on increasing in size, for the world would not hold them, the more dominant groups beat the less dominant. This tendency in the large groups to go on increasing in size and diverging in character, together with the inevitable contingency of much extinction, explains the arrangement of all the forms of life in groups subordinate to groups, all within a few great classes, which has prevailed throughout all time. This grand fact of the grouping of all organic beings under what is called the Natural System, is utterly inexplicable on the theory of creation. As natural selection acts solely by accumulating slight, successive, favourable variations, it can produce no great or sudden modifications; it can act only by short and slow steps. Hence, the canon of "Nature makes no leaps," which every fresh addition to our knowledge tends to confirm, is on this theory intelligible. We can see why throughout nature the same general end is gained by an almost infinite diversity of means, for every peculiarity when once acquired is long inherited, and structures already modified in many different ways have to be adapted for the same general purpose. We can, in short, see why nature is prodigal in variety, though niggard in innovation. But why this should be a law of nature if each species has been independently created no man can explain. Many other facts are, as it seems to me, explicable on this theory. How strange it is that a bird, under the form of a woodpecker, should prey on insects on the ground; that upland geese which rarely or never swim, would possess webbed feet; that a thrush-like bird should dive and feed on sub-aquatic insects; and that a petrel should have the habits and structure fitting it for the life of an auk! and so in endless other cases. But on the view of each species constantly trying to increase in number, with natural selection always ready to adapt the slowly varying descendants of each to any unoccupied or ill-occupied place in nature, these facts cease to be strange, or might even have been anticipated. We can to a certain extent understand how it is that there is so much beauty throughout nature; for this may be largely attributed to the agency of selection. That beauty, according to our sense of it, is not universal, must be admitted by every one who will look at some venomous snakes, at some fishes, and at certain hideous bats with a distorted resemblance to the human face. Sexual selection has given the most brilliant colours, elegant patterns, and other ornaments to the males, and sometimes to both sexes of many birds, butterflies and other animals. With birds it has often rendered the voice of the male musical to the female, as well as to our ears. Flowers and fruit have been rendered conspicuous by brilliant colours in contrast with the green foliage, in order that the flowers may be easily seen, visited and fertilized by insects, and the seeds disseminated by birds. How it comes that certain colours, sounds and forms should give pleasure to man and the lower animals, that is, how the sense of beauty in its simplest form was first acquired, we do not know any more than how certain odours and flavours were first rendered agreeable. As natural selection acts by competition, it adopts and improves the inhabitants of each country only in relation to their co-inhabitants; so that we need feel no surprise at the species of any one country, although on the ordinary view supposed to have been created and specially adapted for that country, being beaten and supplanted by the naturalized productions from another land. Nor ought we marvel if all the contrivances in nature be not, as far as we can judge, absolutely perfect, as in the case even of the human eye; or if some of them be abhorrent to our ideas of fitness. We need not marvel at the sting of the bee, when used against an enemy, causing the bee's own death; at drones being produced in such great numbers for one single act, and being then slaughtered by their sterile sisters; at the astonishing waste of pollen by our fir trees; at the instinctive hatred of the queen bee for her own fertile daughters; at ichneumonidæ feeding within the living bodies of caterpillars; or at other such cases. The wonder indeed, is, on the theory of natural selection, that more cases of the want of absolute perfection have not been detected. The complex and little known laws governing production of varieties are the same, as far as we can judge, with the laws which have governed the production of distinct species. In both cases physical conditions seem to have produced some direct and definite effect, but how much we cannot say. Thus, when varieties enter any new station, they occasionally assume some of the characters proper to the species of that station. With both varieties and species, use and disuse seem to have produced a considerable effect; for it is impossible to resist this conclusion when we look, for instance, at the logger-headed duck, which has wings incapable of flight, in nearly the same condition as in the domestic duck; or when we look at the burrowing tucu-tucu, which is occasionally blind, and then at certain moles, which are habitually blind and have their eyes covered with skin; or when we look at the blind animals inhabiting the dark caves of America and Europe. With varieties and species, correlated variation seems to have played an important part, so that when one part has been modified other parts have been necessarily modified. With both varieties and species, reversions to long-lost characters occasionally occur. How inexplicable on the theory of creation is the occasional appearance of stripes on the shoulders and legs of the several species of the horse-genus and of their hybrids! How simply is this fact explained if we believe that these species are all descended from a striped progenitor, in the same manner as the several domestic breeds of the pigeon are descended from the blue and barred rock pigeon! On the ordinary view of each species having been independently created, why should specific characters, or those by which the species of the same genus differ from each other, be more variable than generic characters in which they all agree? Why, for instance, should the colour of a flower be more likely to vary in any one species of genus, if the other species possess differently coloured flowers, than if all possessed the same coloured flowers? If species are only well-marked varieties, of which the characters have become in a high degree permanent, we can understand this fact; for they have already varied since they branched off from a common progenitor in certain characters, by which they have come to be specifically different from each other; therefore these same characters would be more likely again to vary than the generic characters which have been inherited without change for an immense period. It is inexplicable on the theory of creation why a part developed in a very unusual manner in one species alone of a genus, and therefore, as we may naturally infer, of great importance to that species, should be eminently liable to variation; but, on our view, this part has undergone, since the several species branched off from a common progenitor, an unusual amount of variability and modification, and therefore we might expect the part generally to be still variable. But a part may be developed in the most unusual manner, like the wing of a bat, and yet not be more variable than any other structure, if the part be common to many subordinate forms, that is, if it has been inherited for a very long period; for in this case it will have been rendered constant by long-continued natural selection. Glancing at instincts, marvellous as some are, they offer no greater difficulty than do corporeal structures on the theory of the natural selection of successive, slight, but profitable modifications. We can thus understand why nature moves by graduated steps in endowing certain animals of the same class with their several instincts. I have attempted to show how much light the principle of gradation throws on the admirable architectural powers of the hive-bee. Habit no doubt often comes into play in modifying instincts; but it certainly is not indispensable, as we see in the case of neuter insects, which leave no progeny to inherit the effects of long-continued habit. On the view of all the species of the same genus having descended from a common parent, and having inherited much in common, we can understand how it is that allied species, when placed under widely different conditions of life, yet follow nearly the same instincts; why the thrushes of temperate and tropical South America, for instance, line their nests with mud like our British species. On the view of instincts having been slowly acquired through natural selection, we need not marvel at some instincts being not perfect and liable to mistakes, and at many instincts causing other animals to suffer. If species be only well-marked and permanent varieties, we can see at once why their crossed offspring should follow the same complex laws in their degrees and kinds of resemblance to their parents--in being absorbed into each other by successive crosses, and in other such points--as do the crossed offspring of acknowledged varieties. This similarity would be a strange fact, if species had been independently created and varieties had been produced through secondary laws. If we admit that the geological record is imperfect to an extreme degree, then the facts, which the record does give, strongly support the theory of descent with modification. New species have come on the stage slowly and at successive intervals; and the amount of change after equal intervals of time, is widely different in different groups. The extinction of species and of whole groups of species, which has played so conspicuous a part in the history of the organic world, almost inevitably follows from the principle of natural selection; for old forms are supplanted by new and improved forms. Neither single species nor groups of species reappear when the chain of ordinary generation is once broken. The gradual diffusion of dominant forms, with the slow modification of their descendants, causes the forms of life, after long intervals of time, to appear as if they had changed simultaneously throughout the world. The fact of the fossil remains of each formation being in some degree intermediate in character between the fossils in the formations above and below, is simply explained by their intermediate position in the chain of descent. The grand fact that all extinct beings can be classed with all recent beings, naturally follows from the living and the extinct being the offspring of common parents. As species have generally diverged in character during their long course of descent and modification, we can understand why it is that the more ancient forms, or early progenitors of each group, so often occupy a position in some degree intermediate between existing groups. Recent forms are generally looked upon as being, on the whole, higher in the scale of organization than ancient forms; and they must be higher, in so far as the later and more improved forms have conquered the older and less improved forms in the struggle for life; they have also generally had their organs more specialized for different functions. This fact is perfectly compatible with numerous beings still retaining simple but little improved structures, fitted for simple conditions of life; it is likewise compatible with some forms having retrograded in organization, by having become at each stage of descent better fitted for new and degraded habits of life. Lastly, the wonderful law of the long endurance of allied forms on the same continent--of marsupials [as kangaroos] in Australia, of edentata [as armadillos, sloths, and anteaters] in America, and other such cases--is intelligible, for within the same country the existing and the extinct will be closely allied by descent. Looking to geographical distribution, if we admit that there has been during the long course of ages much migration from one part of the world to another, owing to former climatical and geographical changes and to the many occasional and unknown means of dispersal, then we can understand, on the theory of descent with modification, most of the great leading facts in distribution. We can see why there should be so striking a parallelism in the distribution of organic beings throughout space, and in their geological succession throughout time; for in both cases the beings have been connected by the bond of ordinary generation, and the means of modification have been the same. We see the full meaning of the wonderful fact, which has struck every traveller, namely, that on the same continent, under the most diverse conditions, under heat and cold, on mountain and lowland, on deserts and marshes, most of the inhabitants within each great class are plainly related; for they are the descendants of the same progenitors and early colonists. On this same principle of former migration, combined in most cases with modification, we can understand by the aid of the Glacial period, the identity of some few plants and the close alliance of many others, on the most distant mountains, and in the northern and southern temperate zones; and likewise the close alliance of some of the inhabitants of the sea in the northern and southern temperate latitudes, though separated by the whole inter-tropical ocean. Although two countries may present physical conditions as closely similar as the same species ever acquire, we need feel no surprise at their inhabitants being widely different, if they have been for a long period completely sundered from each other; for as the relation of organism to organism is the most important of all relations, and as the two countries will have received colonists at various periods and in different proportions, from some other country or from each other, the course of modification in the two areas will inevitably have been different. On this view of migration, with subsequent modification, we see why oceanic islands are inhabited by only few species, but of these, why many are peculiar or endemic forms. We clearly see why species belonging to those groups of animals which cannot cross wide spaces of the ocean, as frogs and terrestrial mammals, do not inhabit oceanic islands; and why, on the other hand, new and peculiar species of bats, animals which can traverse the ocean, are often found on islands far distant from any continent. Such cases as the presence of peculiar species of bats on oceanic islands and the absence of all other terrestrial mammals, are facts utterly inexplicable on the theory of independent acts of creation. The existence of closely allied representative species in any two areas, implies on the theory of descent with modification, that the same parent-forms formerly inhabited both areas: and we almost invariably find that wherever many closely allied species inhabit two areas, some identical species are still common to both. Wherever many closely allied yet distant species occur, doubtful forms and varieties belonging to the same groups likewise occur. It is a rule of high generality that the inhabitants of each area are related to the inhabitants of the nearest source whence immigrants might have been derived. We see this in the striking relation of nearly all the plants and animals of the Galapagos Archipelago, of Juan Fernandez, and of the other American islands, to the plants and animals of the neighbouring American mainland; and of those of the Cape Verde Archipelago, and of the other African islands to the African mainland. It must be admitted that these facts receive no explanation on the theory of creation. The fact, as we have seen, that all past and present organic beings can be arranged within a few great classes, in groups subordinate to groups, and with the extinct groups often falling in between the recent groups, is intelligible on the theory of natural selection with its contingencies of extinction and divergence of character. On these same principles we see how it is that the mutual affinities of the forms within each class are so complex and circuitous. We see why certain characters are far more serviceable than others for classification; why adaptive characters derived from rudimentary parts, though of no service to the beings, are often of high classificatory value; and why embryological characters are often the most valuable of all. The real affinities of all organic beings, in contradistinction to their adaptive resemblances, are due to inheritance or community of descent. The Natural System is a genealogical arrangement, with the acquired grades of difference, marked by the terms, varieties, species, genera, families, etc.; and we have to discover the lines of descent by the most permanent characters, whatever they may be, and of however slight vital importance. The similar framework of bones in the hand of a man, wing of a bat, fin of the porpoise, and leg of the horse--the same number of vertebræ forming the neck of the giraffe and of the elephant--and innumerable other such facts, at once explain themselves on the theory of descent with slow and slight successive modifications. The similarity of pattern in the wing and in the leg of a bat, though used for such different purpose--in the jaws and legs of a crab--in the petals, stamens, and pistils of a flower, is likewise, to a large extent, intelligible on the view of the gradual modification of parts or organs, which were aboriginally alike in an early progenitor in each of these classes. On the principle of successive variations not always supervening at an early age, and being inherited at a corresponding not early period of life, we clearly see why the embryos of mammals, birds, reptiles, and fishes should be so closely similar, and so unlike the adult forms. We may cease marvelling at the embryo of an air-breathing mammal or bird having branchial slits and arteries running in loops, like those of a fish which has to breathe the air dissolved in water by the aid of well-developed branchiæ [gills]. Disuse, aided sometimes by natural selection, will often have reduced organs when rendered useless under changed habits or conditions of life; and we can understand on this view the meaning of rudimentary organs. But disuse and selection will generally act on each creature, when it has come to maturity and has to play its full part in the struggle for existence, and will thus have little power in an organ during early life; hence the organ will not be reduced or rendered rudimentary at this early age. The calf, for instance, has inherited teeth, which never cut through the gums of the upper jaw, from an early progenitor having well-developed teeth; and we may believe, that the teeth in the mature animal were formerly reduced by disuse, owing to the tongue and palate, or lips, having become excellently fitted through natural selection to browse without their aid; whereas in the calf, the teeth have been left unaffected, and on the principle of inheritance at corresponding ages have been inherited from a remote period to the present day. On the view of each organism with all its separate parts having been specially created, how utterly inexplicable is it that organs bearing the plain stamp of inutility, such as the teeth in the embryonic calf or the shrivelled wings under the soldered wing covers of many beetles, should so frequently occur. Nature may be said to have taken pains to reveal her scheme of modification, by means of rudimentary organs, of embryological and homologous [corresponding] structures, but we are too blind to understand her meaning. I have now recapitulated the facts and considerations which have thoroughly convinced me that species have been modified, during a long course of descent. This has been effected chiefly through the natural selection of numerous successive, slight, favourable variations; aided in an important manner by the inherited effects of the use and disuse of parts; and in an unimportant manner, that is, in relation to adaptive structures, whether past or present, by the direct action of external conditions, and by variations which seem to us in our ignorance to arise spontaneously. It appears that I formerly underrated the frequency and value of these latter forms of variation, as leading to permanent modifications of structure independently of natural selection. But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous, position--namely, at the close of the Introduction--the following words: "I am convinced that natural selection has been the main but not the exclusive means of modification." This has been of no avail. Great is the power of steady misrepresentation; but the history of science shows that fortunately this power does not long endure. It can hardly be supposed that a false theory would explain, in so satisfactory a manner as does the theory of natural selection, the several large classes of facts above specified. It has recently been objected that this is an unsafe method of arguing; but it is a method used in judging the common events of life, and has often been used by the greatest natural philosophers. The undulatory theory of light has thus been arrived at; and the belief in the revolution of the earth on its own axis was until lately supported by hardly any direct evidence. It is no valid objection that science as yet throws no light on the far higher problems of the essence of the origin of life. Who can explain what is the essence of the attraction of gravity? No one now objects to following out the results consequent on this unknown element of attraction; notwithstanding that Leibnitz formerly accused Newton of introducing "occult qualities and miracles into philosophy." I see no good reasons why the views given in this volume should shock the religious feelings of any one. It is satisfactory, as showing how transient such impressions are, to remember that the greatest discovery ever made by man, namely, the law of the attraction of gravity, was also attacked by Leibnitz, "as subversive of natural, and inferentially of revealed religion." A celebrated author and divine has written to me that "he has gradually learned to see that it is just as noble a conception of the Deity to believe that He created a few original forms capable of self-development into other and needful forms, as to believe that He required a fresh act of creation to supply the voids caused by the action of His laws." Why, it may be asked, until recently did nearly all the most eminent living naturalists and geologists disbelieve in the mutability of species? It cannot be asserted that organic beings in a state of nature are subject to no variation; it cannot be proved that the amount of variation in the course of long ages is a limited quantity; no clear distinction has been, or can be, drawn between species and well-marked varieties. It cannot be maintained that species when intercrossed are invariably sterile and varieties invariably fertile; or that sterility is a special endowment and sign of creation. The belief that species were immutable productions was almost unavoidable as long as the history of the world was thought to be of short duration; and now that we have acquired some idea of the lapse of time, we are too apt to assume, without proof, that the geological record is so perfect that it would have afforded us plain evidence of the mutation of species, if they had undergone mutation. But the chief cause of our natural unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting great changes of which we do not see the steps. The difficulty is the same as that felt by so many geologists, when Lyell first insisted that long lines of inland cliffs had been formed, and great valleys excavated, by the agencies which we still see at work. The mind cannot possibly grasp the full meaning of the term of even a million years; it cannot add up and perceive the full effects of many slight variations, accumulated during an almost infinite number of generations. Although I am fully convinced of the truth of the views given in this volume under the form of an abstract, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as the "plan of creation," "unity of design," etc., and to think that we give an explanation when we only restate a fact. Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject the theory. A few naturalists, endowed with much flexibility of mind, and who have already begun to doubt the immutability of species, may be influenced by this volume; but I look with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality. Whoever is led to believe that species are mutable will do good service by conscientiously expressing his conviction; for thus only can the load of prejudice by which this subject is overwhelmed be removed. Several eminent naturalists have of late published their belief that a multitude of reputed species in each genus are not real species; but that other species are real, that is, have been independently created. This seems to me a strange conclusion to arrive at. They admit that a multitude of forms, which till lately they themselves thought were special creations, and which are still thus looked at by the majority of naturalists, and which consequently have all the external characteristic features of true species--they admit that these have been produced by variation, but they refuse to extend the same view to other and slightly different forms. Nevertheless, they do not pretend that they can define, or even conjecture, which are the created forms of life, and which are those produced by secondary laws. They admit variation as a true cause in one case, they arbitrarily reject it in another, without assigning any distinction in the two cases. The day will come when this will be given as a curious illustration of the blindness of preconceived opinion. These authors seem no more startled at a miraculous act of creation than at an ordinary birth. But do they really believe that at innumerable periods in the earth's history certain elemental atoms have been commanded suddenly to flash into living tissues? Do they believe that at each supposed act of creation one individual or many were produced? Were all the infinite numerous kinds of animals and plants created as eggs or seed, or as full grown? and in the case of mammals, were they created bearing the false marks of nourishment from the mother's womb? Undoubtedly some of these same questions cannot be answered by those who believe in the appearance or creation of only a few forms of life, or of some one form alone. It has been maintained by several authors that it is as easy to believe in the creation of a million beings as of one; but Maupertuis's philosophical axiom "of least action" leads the mind more willingly to admit the smaller number; and certainly we ought not to believe that innumerable beings within each great class have been created with plain, but deceptive, marks of descent from a single parent. As a record of a former state of things, I have retained in the foregoing paragraphs, and elsewhere, several sentences which imply that naturalists believe in the separate creation of each species; and I have been much censured for having thus expressed myself. But undoubtedly this was the general belief when the first edition of the present work appeared. I formerly spoke to very many naturalists on the subject of evolution, and never once met with any sympathetic agreement. It is probable that some did then believe in evolution, but they were either silent or expressed themselves so ambiguously that it was not easy to understand their meaning. Now, things are wholly changed, and almost every naturalist admits the great principle of evolution. There are, however, some who still think that species have suddenly given birth, through quite unexplained means, to new and totally different forms. But, as I have attempted to show, weighty evidence can be opposed to the admission of great and abrupt modifications. Under a scientific point of view, and as leading to further investigation, but little advantage is gained by believing that new forms are suddenly developed in an inexplicable manner from old and widely different forms, over the old belief in the creation of species from the dust of the earth. It may be asked how far I extend the doctrine of the modification of species. The question is difficult to answer, because the more distinct the forms are which we consider, by so much the arguments in favour of community of descent become fewer in number and less in force. But some arguments of the greatest weight extend very far. All the members of whole classes are connected together by a chain of affinities, and all can be classed on the same principle, in groups subordinate to groups. Fossil remains sometimes tend to fill up very wide intervals between existing orders. Organs in a rudimentary condition plainly show that an early progenitor had the organ in a fully developed condition, and this in some cases implies an enormous amount of modification in the descendants. Throughout whole classes various structures are formed on the same pattern, and at a very early age the embryos closely resemble each other. Therefore I cannot doubt that the theory of descent with modification embraces all the members of the same great class or kingdom. I believe that animals are descended from at most only four or five progenitors, and plants from an equal or lesser number. Analogy would lead me one step further, namely, to the belief that all animals and plants are descended from some one prototype. But analogy may be a deceitful guide. Nevertheless all living things have much in common, in their chemical composition, their cellular structure, their laws of growth, and their liability to injurious influences. We see this even in so trifling a fact as that the same poison often similarly affects plants and animals; or that the poison secreted by the gall-fly produces monstrous growths on the wild rose or oak tree. With all organic beings, excepting perhaps some of the very lowest, sexual reproduction seems to be essentially similar. With all, as far as is at present known, the germinal vesicle is the same; so that all organisms start from a common origin. If we look even to the two main divisions--namely, to the animal and vegetable kingdoms--certain low forms are so far intermediate in character that naturalists have disputed to which kingdom they should be referred. As Professor Asa Gray has remarked, "the spores and other reproductive bodies of many of the lower algæ may claim to have first a characteristically animal, and then an unequivocally vegetable existence." Therefore, on the principle of natural selection with divergence of character, it does not seem incredible that, from some such low and intermediate form, both animals and plants may have been developed; and, if we admit this, we must likewise admit that all the organic beings which have ever lived on this earth may be descended from some one primordial form. But this inference is chiefly grounded on analogy, and it is immaterial whether or not it is accepted. No doubt it is possible, as Mr. G. H. Lewes has urged, that at the first commencement of life many different forms were evolved; but if so, we may conclude that only a very few have left modified descendants. For, as I have recently remarked in regard to the members of each great kingdom, such as the Vertebrata, Articulata, etc., we have distinct evidence in their embryological, homologous, and rudimentary structures, that within each kingdom all the members are descended from a single progenitor. When the views advanced by me in this volume, and by Mr. Wallace, or when analogous views on the origin of species are generally admitted, we can dimly foresee that there will be a considerable revolution in natural history. Systematists will be able to pursue their labours as at present; but they will not be incessantly haunted by the shadowy doubt whether this or that form be a true species. This, I feel sure and I speak after experience, will be no slight relief. The endless disputes whether or not some fifty species of British brambles are good species will cease. Systematists will have only to decide (not that this will be easy) whether any form be sufficiently constant and distinct from other forms, to be capable of definition; and if definable, whether the differences be sufficiently important to deserve a specific name. This latter point will become a far more essential consideration than it is at present; for differences, however slight, between any two forms, if not blended by intermediate gradations, are looked at by most naturalists as sufficient to raise both forms to the rank of species. Hereafter we shall be compelled to acknowledge that the only distinction between species and well-marked varieties is, that the latter are known, or believed to be connected at the present day by intermediate gradations, whereas species were formerly thus connected. Hence, without rejecting the considerations of the present existence of intermediate gradations between any two forms, we shall be led to weigh more carefully and to value higher the actual amount of difference between them. It is quite possible that forms now generally acknowledged to be merely varieties may hereafter be thought worthy of specific names; and in this case scientific and common language will come into accordance. In short, we shall have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial combinations made for convenience. This may not be a cheering prospect; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species. The other and more general departments of natural history will rise greatly in interest. The terms used by naturalists, of affinity, relationship, community of type, paternity, morphology [the science of organic form], adaptive characters, rudimentary and aborted organs, etc., will cease to be metaphorical and will have a plain signification. When we no longer look at an organic being as a savage looks at a ship, as something wholly beyond his comprehension; when we regard every production of nature as one which has had a long history; when we contemplate every complex structure and instinct as the summing up of many contrivances, each useful to the possessor, in the same way as any great mechanical invention is the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen; when we thus view each organic being, how far more interesting--I speak from experience--does the study of natural history become! A grand and almost untrodden field of inquiry will be opened, on the causes and laws of variation, on correlation, on the effects of use and disuse, on the direct action of external conditions, and so forth. The study of domestic productions will rise immensely in value. A new variety raised by man will be a more important and interesting subject for study than one more species added to the infinitude of already recorded species. Our classifications will come to be, as far as they can be so made, genealogies; and will then truly give what may be called the plan of creation. The rules for classifying will no doubt become simpler when we have a definite object in view. We possess no pedigree or armorial bearings; and we have to discover and trace the many diverging lines of descent in our natural genealogies, by characters of any kind which have long been inherited. Rudimentary[1] organs will speak infallibly with respect to the nature of long-lost structures. Species and groups of species which are called aberrant, and which may fancifully be called living fossils, will aid us in forming a picture of the ancient forms of life. Embryology will often reveal to us the structure, in some degree obscured, of the prototypes of each great class. When we can feel assured that all the individuals of the same species, and all the closely allied species of most genera, have, within a not very remote period descended from one parent, and have migrated from some one birth-place; and when we better know the many means of migration, then, by the light which geology now throws, and will continue to throw, on former changes of climate and of the level of the land, we shall surely be enabled to trace in an admirable manner the former migrations of the inhabitants of the whole world. Even at present, by comparing the differences between the inhabitants of the sea on the opposite sides of a continent, and the nature of the various inhabitants on that continent in relation to their apparent means of immigration, some light can be thrown on ancient geography. The noble science of geology loses glory from the extreme imperfection of the record. The crust of the earth, with its imbedded remains, must not be looked at as a well-filled museum, but as a poor collection made at hazard and at rare intervals. The accumulation of each great fossiliferous formation will be recognized as having depended on an unusual occurrence of favourable circumstances, and the blank intervals between the successive stages as having been of vast duration. But we shall be able to gauge with some security the duration of these intervals by a comparison of the preceding and succeeding organic forms. We must be cautious in attempting to correlate as strictly contemporaneous two formations, which do not include many identical species, by the general succession of the forms of life. As species are produced and exterminated by slowly acting and still existing causes, and not by miraculous acts of creation; and as the most important of all causes of organic change is one which is almost independent of altered and perhaps suddenly altered physical conditions, namely, the mutual relation of organism to organism--the improvement of one organism entailing the improvement or the extermination of others; it follows, that the amount of organic change in the fossils of consecutive formations probably serves as a fair measure of the relative, though not actual lapse of time. A number of species, however, keeping in a body might remain for a long period unchanged, while within the same period, several of these species, by migrating into new countries and coming into competition with foreign associates, might become modified; so that we must not overrate the accuracy of organic change as a measure of time. In the future I see open fields for far more important researches. Psychology will be securely based on the foundation already well laid by Mr. Herbert Spencer, that of the necessary acquirement of each mental power and capacity by gradation. Much light will be thrown on the origin of man and his history. Authors of the highest eminence seem to be fully satisfied with the view that each species has been independently created. To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual. When I view all beings as not special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Cambrian system was deposited, they seem to me to become ennobled. Judging from the past, we may safely infer that not one living species will transmit its unaltered likeness to a distant futurity. And of the species now living very few will transmit progeny of any kind to a far distant futurity; for the manner in which all organic beings are grouped, shows that the greater number of species in each genus, and all the species in many genera, have left no descendants, but have become utterly extinct. We can so far take a prophetic glance into futurity as to foretell that it will be the common and widely spread species, belonging to the larger and dominant groups within each class, which will ultimately prevail and procreate new and dominant species. As all the living forms of life are the lineal descendants of those which lived long before the Cambrian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no cataclysm has desolated the whole world. Hence, we may look with some confidence to a secure future of great length. And as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress toward perfection. It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. These laws taken in the largest sense, being growth with reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life, and from use and disuse: a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing divergence of Character and the Extinction of less improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, while this planet has gone circling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved. FOOTNOTES: [1] _Vestigial_ is now preferred to _rudimentary_ as a term.--Ed. HOW "THE ORIGIN OF SPECIES" CAME TO BE WRITTEN. [An extract from the autobiography of Charles Darwin, in "The Life and Letters of Charles Darwin," New York, D. Appleton & Co.] From September, 1854, I devoted my whole time to arranging my huge pile of notes, to observing and to experimenting in relation to the transmutation of species. During the voyage of the _Beagle_ I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos; secondly, by the manner in which closely allied animals replace one another in proceeding southwards over the continent; and, thirdly, by the South American character of most of the productions of the Galapagos Archipelago, and more especially by the manner in which these differ slightly on each island of the group, none of these islands appearing to be very ancient in a geological sense. It was evident that such facts as these, as well as many others, could only be explained on the supposition that species gradually become modified; and the subject haunted me. But it was equally evident that neither the action of the surrounding conditions, nor the will of the organisms (especially in the case of plants) could account for the innumerable cases in which organisms of every kind are beautifully adapted to their habits of life--for instance, a woodpecker or a tree-frog to climb trees, or a seed for dispersal by hooks or plumes. I had always been much struck by such adaptations, and until these could be explained it seemed to me almost useless to endeavour to prove by indirect evidence that species have been modified. After my return to England it appeared to me that by following the example of Lyell in geology,[2] and by collecting all facts that bore in any way on the variation of animals and plants under domestication and nature, some light might perhaps be thrown on the whole subject. My first note-book was opened in July, 1837. I worked on true Baconian principles, and without any theory collected facts on a wholesale scale, more especially with respect to domesticated productions, by printed enquiries, by conversation with skilful breeders and gardeners and by extensive reading. When I see the list of books of all kinds which I read and abstracted, including whole series of journals and translations, I am surprised at my industry. I soon perceived that selection was the keystone of man's success in making useful races of animals and plants. But how selection could be applied to organisms living in a state of nature remained for some time a mystery to me. In October, 1838, that is fifteen months after I had begun my systematic enquiry, I happened to read for amusement "Malthus on Population," and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved and unfavourable ones to be destroyed. The result of this would be the formation of a new species. Here then I had at last got a theory by which to work; but I was so anxious to avoid prejudice that I determined not for some time to write even the briefest sketch of it. In June, 1842, I first allowed myself the satisfaction of writing a very brief abstract of my theory in pencil in 35 pages; and this was enlarged during the summer of 1844 into one of 230 pages, which I had fairly copied out and still possess. But at that time I overlooked one problem of great importance; and it is astonishing to me, except on the principle of Columbus and his egg, how I could have overlooked it and its solution. This problem is the tendency in organic beings descended from the same stock to diverge in character as they become, modified. That they have diverged greatly is obvious from the manner in which species of all kinds can be classed under genera, genera under families, families under sub-orders and so forth; and I can remember the very spot on the road, whilst in my carriage, when to my joy the solution occurred to me; and this was long after I had come to Down. This solution, as I believe, is that the modified offspring of all dominant and increasing forms tend to become adapted to many and highly diversified places in the economy of nature. Early in 1856 Lyell advised me to write out my views pretty fully, and I began at once to do so on a scale three or four times as extensive as that which was afterwards followed in my "Origin of Species;" yet it was only an abstract of the materials which I had collected and I got through about half the work on this scale. But my plans were overthrown, for early in the summer of 1858 Mr. Wallace, who was then in the Malay Archipelago, sent me an essay "On the tendency of varieties to depart indefinitely from the original type;" and this essay contained exactly the same theory as mine.[3] Mr. Wallace expressed the wish that if I thought well of his essay I should send it to Lyell for perusal. The circumstances under which I consented at the request of Lyell and Hooker to allow of an abstract from my MS., together with a letter to Asa Gray, dated September 5, 1857, to be published at the same time with Wallace's essay, are given in the "Journal of the Proceedings of the Linnean Society," 1858, p. 45. I was at first very unwilling to consent, as I thought Mr. Wallace might consider my doing so unjustifiable, for I did not then know how generous and noble was his disposition. The extract from my MS. and the letter to Asa Gray had neither been intended for publication, and were badly written. Mr. Wallace's essay, on the other hand, was admirably expressed and quite clear. Nevertheless, our joint productions excited very little attention, and the only published notice of them which I can remember was by Professor Haughton of Dublin, whose verdict was that all that was new in them was false, and what was true was old. This shows how necessary it is that any new idea should be explained at considerable length in order to arouse public attention. In September, 1858, I set to work by the strong advice of Lyell and Hooker to prepare a volume on the transmutation of species, but was often interrupted by ill health and short visits to Dr. Lane's delightful hydropathic establishment at Moor Park. I abstracted the MS. begun on a much larger scale in 1856, and completed the volume on the same reduced scale. It cost me thirteen months and ten days' hard labor. It was published under the title of the "Origin of Species," in November, 1859. Though considerably added to and corrected in the later editions, it has remained substantially the same book. It is no doubt the chief work of my life. It was from the first highly successful. The first small edition of 1,250 copies was sold on the day of publication, and a second edition of 3,000 copies soon afterwards. Sixteen thousand copies have now (1876) been sold in England; and considering how stiff a book it is, this is a large sale. It has been translated into almost every European tongue, even into such languages as Spanish, Bohemian, Polish and Russian. Even an essay in Hebrew has appeared on it, showing that the theory is contained in the Old Testament! The reviews were very numerous; for some time all that appeared on the "Origin" and on my related books, and these amount (excluding newspaper reviews) to 265; but after a time I gave up the attempt in despair. Many separate essays and books on the subject have appeared; and in Germany a catalogue or bibliography on "Darwinismus" has appeared every year or two. The success of the "Origin" may, I think, be attributed in large part to my having long before written two condensed sketches and to my having abstracted a much larger manuscript, which was itself an abstract. By this means I was enabled to select the more striking facts and conclusions. I had also, during many years followed a golden rule, namely, that whenever a published fact, a new observation or thought came across me, which was opposed to my general results, to make a memorandum of it without fail and at once; for I had found by experience that such facts and thoughts were far more apt to escape from the memory than favourable ones. Owing to this habit very few objections were raised against my views which I had not at least noticed and attempted to answer. It has sometimes been said that the success of the "Origin" proved "that the subject was in the air," or "that men's minds were prepared for it." I do not think that this is strictly true, for I occasionally sounded not a few naturalists, and never happened to come across a single one who seemed to doubt about the permanence of species. Even Lyell and Hooker, though they listened with interest to me, never seemed to agree. I tried once or twice to explain to able men what I meant by Natural Selection, but signally failed. What I believe was strictly true is that innumerable well-observed facts were stored in the minds of naturalists ready to take their proper places as soon as any theory which would receive them was sufficiently explained. Another element in the success of the book was its moderate size; and this I owe to the appearance of Mr. Wallace's essay; had I published on the scale on which I began to write in 1856, the book would have been four or five times as large as the "Origin," and very few would have had the patience to read it. I gained much by my delay an publishing from about, 1839, when the theory was clearly conceived, to 1859; and I lost nothing by it, for I cared very little whether men attributed most originality to me or Wallace; and his essay no doubt aided in the reception of the theory. I was forestalled in only one important point, which my vanity has always made me regret, namely, the explanation by means of the Glacial period of the presence of the same species of plants and of some few animals on distant mountain summits and in the arctic regions. This view pleased me so much that I wrote it out _in extenso_, and I believe that it was read by Hooker some years before E. Forbes published in 1846 his celebrated memoir on the subject. In the very few points in which we differed, I still think that I was in the right. I have never, of course, alluded in print to my having independently worked out this view. Hardly any point gave me so much satisfaction when I was at work on the "Origin," as the explanation of the wide difference in many classes between the embryo and the adult animal, and of the close resemblance of the embryos within the same class. No notice of this point was taken, as far as I remember, in the early reviews of the "Origin," and I recollect expressing my surprise on this head in a letter to Asa Gray. Within late years several reviewers have given the whole credit to Fritz Muller and Haeckel, who undoubtedly have worked it out much more fully and in some respects more correctly than I did. I had materials for a whole chapter on the subject, and I ought to have made the discussion longer; for it is clear that I failed to impress my readers; and he who succeeds in doing so deserves, in my opinion, all the credit. This leads me to remark that I have almost always been treated honestly by my reviewers, passing over those without scientific knowledge as not worthy of notice. My views have been grossly misrepresented, bitterly opposed and ridiculed, but this has been generally done as, I believe, in good faith. On the whole, I do not doubt that my works have been over and over again greatly overpraised. I rejoice that I have avoided controversies, and this I owe to Lyell, who many years ago, in reference to my geological works, strongly advised me never to get entangled in a controversy, as it rarely did any good and caused a miserable loss of time and temper. Whenever I have found out that I have blundered, or that my work has been imperfect, and when I have been contemptuously criticised, and even when I have been overpraised, so that I have felt mortified, it has been my greatest comfort to say hundreds of times to myself that "I have worked as hard and as well as I could, and no man can do more than this." I remember when in Good Success Bay, in Tierra del Fuego, thinking (and, I believe, that I wrote home to the effect) that I could not employ my life better than in adding a little to Natural Science. This I have done to the best of my abilities, and critics may say what they like, but they can not destroy this conviction. FOOTNOTES: [2] See Masterpieces of Science, Vol. I, "Earth and Sky," Sir Charles Lyell on Uniformity in geological change. [3] The essay appears in "Natural Selection," London, 1870. THE DESCENT OF MAN CHARLES DARWIN [Concluding chapter of "The Descent of Man," New York, D. Appleton & Co.] A brief summary will be sufficient to recall to the reader's mind the more salient points in this work. Many of the views which have been advanced are highly speculative, and some, no doubt, will prove erroneous; but I have in every case given the reasons which have led me to one view rather than to another. It seemed worth while to try how far the principle of evolution would throw light on some of the more complex problems in the natural history of man. False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for every one takes a salutary pleasure in proving their falseness; and, when this is done, one path toward error is closed and the road to truth is often at the same time opened. The main conclusion arrived at in this work, and now held by many naturalists who are well competent to form a sound judgment, is that man is descended from some less highly organized form. The grounds upon which this conclusion rests will never be shaken, for the close similarity between man and the lower animals in embryonic development, as well as in innumerable points of structure and constitution, both of high and of the most trifling importance--the rudiments which he retains, and the abnormal reversions to which he is occasionally liable--are facts which cannot be disputed. They have long been known, but, until recently, they told us nothing with respect to the origin of man. Now, when viewed by the light of our knowledge of the whole organic world, their meaning is unmistakable. The great principle of evolution stands up clear and firm when these groups of facts are considered in connection with others, such as the mutual affinities of the members of the same group, their geographical distribution in past and present times, and their geological succession. It is incredible that all these facts should speak falsely. He who is not content to look, like a savage, at the phenomena of Nature as disconnected, cannot any longer believe that man is the work of a separate act of creation. He will be forced to admit that the close resemblance of the embryo of man to that, for instance, of a dog--the construction of his skull, limbs and whole frame on the same plan with that of other mammals--the occasional appearance of various structures, for instance, of several distinct muscles, which man does not normally possess, but which are common to the Quadrumana--and a crowd of analogous facts--all point in the plainest manner to the conclusion that man is the co-descendant of other mammals of a common progenitor. We have seen that man incessantly presents individual differences in all parts of his body and in his mental faculties. These differences or variations seem to be induced by the same general causes, and to obey the same laws as with the lower animals. In both cases similar laws of inheritance prevail. Man tends to increase at a greater rate than his means of subsistence; consequently he is occasionally subjected to a severe struggle for existence, and natural selection will have effected whatever lies within its scope. A succession of strongly marked variations of a similar nature is by no means requisite; slight fluctuating differences in the individual suffice in the work of natural selection. We may feel assured that the inherited effects of the long-continued use or disuse of parts will have done much in the same direction with natural selection. Modifications formerly of importance, though no longer of any special use, are long-inherited. When one part is modified other parts change through the principle of correlation, of which we have instances in many curious cases of correlated monstrosities. Something may be attributed to the direct and definite action of the surrounding conditions of life, such as abundant food, heat or moisture; and, lastly, many characters of slight physiological importance, some indeed of considerable importance, have been gained through sexual selection. No doubt man, as well as every other animal, presents structures, which, as far as we can judge with our little knowledge, are not now of any service to him, nor to have been so during any former period of his existence, either in relation to his general conditions of life, or of one sex to the other. Such structures cannot be accounted for by any form of selection, or by the inherited effects of the use and disuse of parts. We know, however, that many strange and strongly marked peculiarities of structure occasionally appear in our domesticated productions, and if the unknown causes which produce them were to act more uniformly, they would probably become common to all the individuals of the species. We may hope hereafter to understand something about the causes of such occasional modifications, especially through the study of monstrosities; hence, the labours of experimentalists, such as those of M. Camille Dareste, are full of promise for the future. In general we can only say that the cause of each slight variation and of each monstrosity lies much more in the constitution of the organism than in the nature of the surrounding conditions; though new and changed conditions certainly play an important part in exciting organic changes of many kinds. Through the means just specified, aided perhaps by others as yet undiscovered, man has been raised to his present state. But since he attained to the rank of manhood, he has diverged into distinct races, or, as they may be more fitly called, subspecies. Some of these, such as the negro and European, are so distinct that, if specimens had been brought to a naturalist without any further information, they would undoubtedly have been considered by him as good and true species. Nevertheless, all the races agree in so many unimportant details of structure and in so many mental peculiarities, that these can be accounted for only by inheritance from a common progenitor; and a progenitor thus characterized would probably deserve to rank as man. It must not be supposed that the divergence of each race from the other races, and of all from a common stock, can be traced back to any one pair of progenitors. On the contrary, at every stage in the process of modification, all the individuals which were in any way best fitted for their conditions of life, though in different degrees, would have survived in greater numbers than the less well-fitted. The process would have been like that followed by man, when he does not intentionally select particular individuals, but breeds from all the superior individuals and neglects all the inferior individuals. He thus slowly but surely modifies his stock and unconsciously forms a new strain. So with respect to modifications acquired independently of selection, and due to variations arising from the nature of the organism and the action of the surrounding conditions, or from changed habits of life, no single pair will have been modified in a much greater degree than the other pairs which inhabit the same country, for all will have been continually blended through free intercrossing. By considering the embryological structure of man--the homologies [parallels] which he presents with the lower animals--the rudiments which he retains--and the reversions to which he is liable, we can partly recall in imagination the former condition of our early progenitors; and can approximately place them in their proper place in the zoological series. We thus learn that man is descended from a hairy, tailed quadruped, probably arboreal in its habits [living on or among trees] and an inhabitant of the Old World. This creature, if its whole structure had been examined by a naturalist, would have been classed among the Quadrumana, as surely as the still more ancient progenitor of the Old and New World monkeys. The Quadrumana and all the higher mammals are probably derived from an ancient marsupial animal [usually provided with a pouch for the reception and nourishment of the young, as in the case of the kangaroo] and this through a long line of diversified forms, from some reptile-like or some amphibian-like creature, and this again from some fish-like animal. In the dim obscurity of the past we can see that the early progenitor of all the Vertebrata must have been an aquatic animal, provided with branchiæ [gills], with the two sexes united in the same individual, and with the most important organs of the body (such as the brain and heart) imperfectly or not at all developed. This animal seems to have been more like the larvæ of the existing marine Ascidians than any other known form. The greatest difficulty which presents itself when we are driven to the above conclusion on the origin of man is the high standard of intellectual power and of moral disposition which he has attained. But every one who admits the principle of evolution must see that the mental powers of the higher animals, which are the same in kind with those of man, though so different in degree, are capable of advancement. Thus the interval between the mental powers of one of the higher apes and of a fish, or between those of an ant and scale-insect, is immense; yet their development does not offer any special difficulty; for with our domesticated animals the mental faculties are certainly variable, and the variations are inherited. No one doubts that they are of the utmost importance to animals in a state of nature. Therefore, the conditions are favourable for their development through natural selection. The same conclusion may be extended to man; the intellect must have been all-important to him, even at a very remote period, as enabling him to invent and use language, to make weapons, tools, traps, etc., whereby with the aid of his social habits he long ago became the most dominant of all living creatures. A great stride in the development of the intellect will have followed, as soon as the half-art and half-instinct of language came into use; for the continued use of language will have reacted on the brain and produced an inherited effect; and this again will have reacted on the improvement of language. As Mr. Chauncey Wright has well remarked, the largeness of the brain in man relatively to his body, compared with the lower animals, may be attributed in chief part to the early use of some simple form of language--that wonderful engine which affixes signs to all sorts of objects and qualities, and excites trains of thought which would never arise from the mere impression of the senses, or if they did arise could not be followed out. The higher intellectual powers of man, such as those of ratiocination, abstraction, self-consciousness, etc., will have followed from the continued improvement of other mental faculties; but without considerable culture of the mind, both in the race and in the individual, it is doubtful whether these high powers would be exercised and thus fully attained. The development of the moral qualities is a more interesting problem. The foundation lies in the social instincts, including under this term the family ties. These instincts are highly complex, and in the case of the lower animals give special tendencies toward certain definite actions; but the more important elements are love and the distinct emotion of sympathy. Animals endowed with the social instincts take pleasure in one another's company, warn one another of danger, defend and aid one another in many ways. These instincts do not extend to all the individuals of the species, but only to those of the same community. As they are highly beneficial to the species they have in all probability been acquired through natural selection. A moral being is one who is capable of reflecting on his past actions and their motives--of approving of some and disapproving of others; and the fact that man is the one being who certainly deserves this designation is the greatest of all distinctions between him and the lower animals. But in the fourth chapter I have endeavoured to show that the moral sense follows, firstly, from the enduring and ever-present nature of the social instincts; secondly, from man's appreciation of the approbation and disapprobation of his fellows; and, thirdly, from the high activity of his mental faculties, with past impressions extremely vivid; and in these latter respects he differs from the lower animals. Owing to this condition of mind, man cannot avoid looking both backward and forward and comparing past impressions. Hence, after some temporary desire or passion has mastered his social instincts, he reflects and compares the now weakened impression of such past impulses with the ever-present social instincts; and he then feels that sense of dissatisfaction which all unsatisfied instincts leave behind them, he therefore resolves to act differently for the future--and this is conscience. Any instinct permanently stronger or more enduring than another gives rise to a feeling which we express by saying that it ought to be obeyed. A pointer dog if able to reflect on his past conduct would say to himself, I ought (as indeed we say of him) to have pointed at that hare and not have yielded to the passing temptation of hunting it. Social animals are impelled partly by a wish to aid the members of their community in a general manner, but more commonly to perform certain definite actions. Man is impelled by the same general wish to aid his fellows; but has few or no special instincts. He differs also from the lower animals in the power of expressing his desires by words, which thus become a guide to the aid required and bestowed. The motive to give aid is likewise much modified in man; it no longer consists solely of a blind instinctive impulse, but is much influenced by the praise or blame of his fellows. The appreciation and bestowal of praise and blame both rest on sympathy; and this emotion, as we have seen, is one of the most important elements of the social instincts. Sympathy, though gained as an instinct, is also much strengthened by exercise or habit. As all men desire their own happiness, praise or blame is bestowed on actions or motives according as they lead to this end; and as happiness is an essential part of the general good the greatest-happiness principle indirectly serves as a nearly safe standard of right and wrong. As the reasoning powers advance and experience is gained the remoter effects of certain lines of conduct on the character of the individual and on the general good are perceived; and then the self-regarding virtues come within the scope of public opinion and receive praise and their opposites blame. But with the less civilized nations reason often errs, and many bad customs and base superstitions come within the same scope and are then esteemed as high virtues and their breach as heavy crimes. The moral faculties are generally and justly esteemed as of higher value than the intellectual powers. But we should bear in mind that the activity of the mind in vividly recalling past impressions is one of the fundamental though secondary bases of conscience. This affords the strongest argument for educating and stimulating in all possible ways the intellectual faculties of every human being. No doubt, a man with a torpid mind, if his social affections and sympathies are well developed, will be led to good actions and may have a fairly sensitive conscience. But whatever renders the imagination more vivid and strengthens the habit of recalling and comparing past impressions will make the conscience more sensitive, and may even somewhat compensate for weak social affections and sympathies. The moral nature of man has reached its present standard partly through the advancement of his reasoning powers and consequently of a just public opinion, but especially from his sympathies having been rendered more tender and widely diffused through the effects of habit, example, instruction and reflection. It is not improbable that after long practice virtuous tendencies may be inherited. With the more civilized races the conviction of the existence of an all-seeing Deity has had a potent influence on the advance of morality. Ultimately man does not accept the praise or blame of his fellows as his sole guide, though few escape this influence, but his habitual convictions, controlled by reason, afford him the safest rule. His conscience then becomes the supreme judge and monitor. Nevertheless, the first foundation or origin of the moral sense lies in the social instincts, including sympathy; and these instincts, no doubt, were primarily gained, as in the case of the lower animals, through natural selection. The belief in God has often been advanced as not only the greatest but the most complete of all the distinctions between man and the lower animals. It is, however, impossible, as we have seen, to maintain that this belief is innate or instinctive in man. On the other hand, a belief in all-pervading spiritual agencies seems to be universal, and apparently follows from a considerable advance in man's reason and from a still greater advance in his faculties of imagination, curiosity and wonder. I am aware that the assumed instinctive belief in God has been used by many persons as an argument for His existence. But this is a rash judgment, as we should thus be compelled to believe in the existence of many cruel and malignant spirits, only a little more powerful than man; for the belief in them is far more general than in a beneficent Deity. The idea of a universal and beneficent Creator does not seem to arise in the mind of man until he has been elevated by long-continued culture. He who believes in the advancement of man from some low organized form will naturally ask, How does this bear on the belief in the immortality of the soul? The barbarous races of man, as Sir J. Lubbock has shown, possess no clear belief of this kind; but arguments derived from the primeval beliefs of savages are, as we have just seen, of little or no avail. Few persons feel any anxiety from the impossibility of determining at what precise period in the development of the individual, from the first trace of a minute germinal vesicle, man becomes an immortal being; and there is no greater cause for anxiety because the period in the gradually ascending organic scale cannot possibly be determined. I am aware that the conclusions arrived at in this work will be denounced by some as highly irreligious; but he who denounces them is bound to show why it is more irreligious to explain the origin of man as a distinct species by descent from some lower form, through the laws of variation and natural selection, than to explain the birth of the individual through the laws of ordinary reproduction. The birth both of the species and of the individual are equally parts of that grand sequence of events, which our minds refuse to accept as the result of blind chance. The understanding revolts at such a conclusion, whether or not we are able to believe that every slight variation of structure, the union of each pair in marriage, the dissemination of each seed, and other such events have all been ordained for some special purpose. Sexual selection has been treated at great length in this work; for, as I have attempted to show, it has played an important part in the history of the organic world. I am aware that much remains doubtful, but I have endeavoured to give a fair view of the whole case. In the lower divisions of the animal kingdom sexual selection seems to have done nothing; such animals are often affixed for life to the same spot, or have the sexes combined in the same individual, or, what is still more important, their perceptive and intellectual faculties are not sufficiently advanced to allow of the feelings of love and jealousy, or of the exertion of choice. When, however, we come to the Arthropoda and Vertebrata, even to the lowest classes in these two great sub-kingdoms, sexual selection has effected much; and it deserves notice that we here find the intellectual faculties developed, but in two very distinct lines, to the highest standard, namely in the Hymenoptera [ants, bees, etc.], among the Arthropoda [many insects, spiders, etc.], and in the Mammalia, including man, among the Vertebrata. In the most distinct classes of the animal kingdom--in mammals, birds, fishes, insects and even crustaceans--the differences between the sexes follow almost exactly the same rules. The males are almost always the wooers; and they alone are armed with special weapons for fighting with their rivals. They are generally stronger and larger than the females, and are endowed with the requisite qualities of courage and pugnacity. They are provided, either exclusively or in a much higher degree than the females, with organs for vocal or instrumental music, and with odoriferous glands. They are ornamented with infinitely diversified appendages and with the most brilliant or conspicuous colors, often arranged in elegant patterns, while the females are unadorned. When the sexes differ in more important structures it is the male which is provided with special sense-organs for discovering the female, with locomotive organs for reaching her, and often with prehensile organs for holding her. These various structures for charming or securing the female are often developed in the male during only part of the year; namely, the breeding season. They have in many cases been transferred in a greater or less degree to the females; and in the latter case they often appear in her as mere rudiments. They are lost or never gained by the males after emasculation. Generally they are not developed in the male during early youth, but appear a short time before the age for reproduction. Hence, in most cases the young of both sexes resemble each other; and the female somewhat resembles her young offspring throughout life. In almost every great class a few anomalous cases occur, where there has been an almost complete transposition of the characters proper to the two sexes; the females assuming characters which properly belong to the males. This surprisingly uniformity in the laws regulating the differences between the sexes in so many and such widely separated classes is intelligible if we admit the action throughout all the higher divisions of the animal kingdom of one common cause; namely, sexual selection. Sexual selection depends on the success of certain individuals over others of the same sex, in relation to the propagation of the species; while natural selection depends on the success of both sexes, at all ages, in relation to the general conditions of life. The sexual struggle is of two kinds; in the one it is between the individuals of the same sex, generally the males, in order to drive away or kill their rivals, the females remaining passive; while in the other, the struggle is likewise between the individuals of the same sex, in order to excite or charm those of the opposite sex, generally the females, which no longer remain passive, but select the more agreeable partners. This latter kind of selection is closely analogous to that which man unintentionally, yet effectually, brings to bear on his domesticated productions, when he preserves during a long period the most pleasing or useful individuals, without any wish to modify the breed. The laws of inheritance determine whether characters gained through sexual selection by either sex shall be transmitted to the same sex, or to both; as well as the age at which they shall be developed. It appears that variations arising late in life are commonly transmitted to one and the same sex. Variability is the necessary basis for the action of selection and is wholly independent of it. It follows from this that variations of the same general nature have often been taken advantage of and accumulated through sexual selection in relation to the propagation of the species, as well as through natural selection in relation to the general purposes of life. Hence secondary sexual characters, when equally transmitted to both sexes, can be distinguished from ordinary specific characters only by the light of analogy. The modifications acquired through sexual selection are often so strongly pronounced that the two sexes have frequently been ranked as distinct species, or even as distinct genera. Such strongly marked differences must be in some manner highly important; and we know that they have been acquired in some instances at the cost not only of inconvenience, but of exposure to actual danger. The belief in the power of sexual selection rests chiefly on the following considerations: The characters which we have the best reasons for supposing to have been thus acquired are confined to one sex; and this alone renders it probable that in most cases they are connected with the act of reproduction. These characters in innumerable instances are fully developed only at maturity; and often during only a part of the year, which is always the breeding season. The males (passing over a few exceptional cases) are the more active in courtship; they are the best armed, and are rendered the most attractive in various ways. It is to be especially observed that the males display their attractions with elaborate care in the presence of the females; and that they rarely or never display them excepting during the season of love. It is incredible that all this should be purposeless. Lastly, we have distinct evidence with some quadrupeds and birds that the individuals of one sex are capable of feeling a strong antipathy or preference for certain individuals of the other sex. Bearing in mind these facts and not forgetting the marked results of man's unconscious selection, it seems to me almost certain that if the individuals of one sex were during a long series of generations to prefer pairing with certain individuals of the other sex, characterized in some peculiar manner, the offspring would slowly but surely become modified in this same manner. I have not attempted to conceal that, excepting when the males are more numerous than the females, or when polygamy prevails, it is doubtful how the more attractive males succeed in leaving a larger number of offspring to inherit their superiority in ornaments or other charms than the less attractive males; but I have shown that this would probably follow from the females--especially the more vigorous ones, which would be the first to breed--preferring not only the more attractive but at the same time the more vigorous and victorious males. Although we have some positive evidence that birds appreciate bright and beautiful objects, as with the bower-birds of Australia, and although they certainly appreciate the power of song, yet I fully admit that it is astonishing that the females of many birds and some mammals should be endowed with sufficient taste to appreciate ornaments, which we have reason to attribute to sexual selection; and this is even more astonishing in the case of reptiles, fish and insects. But we really know little about the minds of the lower animals. It cannot be supposed, for instance, that male birds of paradise or peacocks should take such pains in erecting, spreading and vibrating their beautiful plumes before the males for no purpose. We should remember the fact given on excellent authority in a former chapter that several peahens, when debarred from an admired male, remained widows during a whole season rather than pair with another bird. Nevertheless, I know of no fact in natural history more wonderful than that the female Argus pheasant should appreciate the exquisite shading of the ball-and-socket ornaments and the elegant patterns on the wing feathers of the male. He who thinks that the male was created as he now exists must admit that the great plumes, which prevent the wings from being used for flight and which, as well as the primary feathers, are displayed in a manner quite peculiar to this one species during the act of courtship, and at no other time, were given to him as an ornament. If so, he must likewise admit that the female was created and endowed with the capacity of appreciating such ornaments. I differ only in the conviction that the male Argus pheasant acquired his beauty gradually, through the females having preferred during many generations the more highly ornamented males; the esthetic capacity of the females having been advanced through exercise or habit just as our own taste is gradually improved. In the male, through the fortunate chance of a few feathers not having been modified, we can distinctly see how simple spots with a little fulvous [tawny] shading on one side may have been developed by small steps into the wonderful ball-and-socket ornaments; and it is probable that they were actually thus developed. Every one who admits the principle of evolution, and yet feels great difficulty in admitting that female mammals, birds, reptiles and fish, could have acquired the high taste implied by the beauty of the males, and which generally coincides with our own standard, should reflect that the nerve-cells of the brain in the highest as well as in the lowest members of the Vertebrate series, are derived from those of the common progenitor of the whole group. It thus becomes intelligible that the brain and mental faculties should be capable under similar conditions of nearly the same course of development, and consequently of performing nearly the same functions. The reader who has taken the trouble to go through the several chapters devoted to sexual selection will be able to judge how far the conclusions at which I have arrived are supported by sufficient evidence. If he accepts these conclusions he may, I think, safely extend them to mankind; but it would be superfluous here to repeat what I have so lately said on the manner in which sexual selection apparently has acted on man, both on the male and female side, causing the two sexes of man to differ in body and mind, and the several races to differ from each other in various characters, as well as from their ancient and lowly organized progenitors. He who admits the principle of sexual selection will be led to the remarkable conclusion that the cerebral system not only regulates most of the existing functions of the body, but has indirectly influenced the progressive development of various bodily structures and of certain mental qualities. Courage, pugnacity, perseverance, strength and size of body, weapons of all kinds, musical organs, both vocal and instrumental, bright colours, stripes and marks, and ornamental appendages, have all been indirectly gained by the one sex or the other, through the influence of love and jealousy, through the appreciation of the beautiful in sound, colour or form, and through the exertion of a choice; and those powers of the mind manifestly depend on the development of the cerebral system. Man scans with scrupulous care the character and pedigree of his horses, cattle and dogs before he matches them; but when he comes to his own marriage he rarely, or never takes any such care. He is impelled by nearly the same motives as the lower animals when left to their own free choice, though he is in so far superior to them that he highly values mental charms and virtues. On the other hand he is strongly attracted by mere wealth or rank. Yet he might by selection do something not only for the bodily constitution and frame of his offspring, but for their intellectual and moral qualities. Both sexes ought to refrain from marriage if they are in any marked degree inferior in body or mind; but such hopes are Utopian and will never be even partially realized until the laws of inheritance are thoroughly known. All do good service who aid toward this end. When the principles of breeding and inheritance are better understood, we shall not hear ignorant members of our legislature rejecting with scorn a plan for ascertaining whether or not consanguineous marriages are injurious to man. The advancement of the welfare of mankind is a most intricate problem; all ought to refrain from marriage who cannot avoid abject poverty for their children; for poverty is not only a great evil, but tends to its own increase by leading to recklessness in marriage. On the other hand, as Mr. Galton has remarked, if the prudent avoid marriage, while the reckless marry, the inferior members tend to supplant the better members of society. Man, like every other animal, has no doubt advanced to his present high condition through a struggle for existence consequent on his rapid multiplication; and if he is to advance still higher, he must remain subject to a severe struggle. Otherwise he would sink into indolence, and the more gifted men would not be more successful in the battle of life than the less gifted. Hence our natural rate of increase, though leading to many and obvious evils, must not be greatly diminished by any means. There should be open competition for all men; and the most able should not be prevented by laws or customs from succeeding best and rearing the largest number of offspring. Important as the struggle for existence has been and even still is, yet as far as the highest part of man's nature is concerned there are other agencies more important. For the moral qualities are advanced, either directly or indirectly, much more through the effects of habit, the reasoning powers, instruction, religion, etc., than through natural selection; though to this latter agency the social instincts, which afforded the basis for the development of the moral sense, may be safely attributed. The main conclusion arrived at in this work, namely, that man is descended from some lowly organized form, will, I regret to think, be highly distasteful to many. But there can hardly be a doubt that we are descended from barbarians. The astonishment I felt on first seeing a party of Fuegians on a wild and broken shore will never be forgotten by me, for the reflection at once rushed into my mind--such were our ancestors. These men were absolutely naked and bedaubed with paint, their long hair was tangled, their mouths frothed with excitement, and their expression was wild, startled and distrustful. They possessed hardly any arts, and like wild animals lived on what they could catch; they had no government, and were merciless to every one not of their own small tribe. He who has seen a savage in his native land will not feel much shame, if forced to acknowledge that the blood of some more humble creature flows in his veins. For my own part I would as soon be descended from that heroic little monkey who braved his dreaded enemy in order to save the life of his keeper; or from that old baboon, who, descending from the mountains, carried away in triumph his young comrade from a crowd of astonished dogs--as from a savage who delights to torture his enemies, offers up bloody sacrifices, practises infanticide without remorse, treats his wives like slaves, knows no decency, and is haunted by the grossest superstitions. Man may be excused for feeling some pride at having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen, instead of having been aboriginally placed there, may give him hope for a still higher destiny in the distant future. But we are not here concerned with hopes or fears, only with the truth as far as our reason permits us to discover it. I have given the evidence to the best of my ability, and we must acknowledge, as it seems to me, that man, with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his godlike intellect which has penetrated into the movements and constitution of the solar system--with all these exalted powers--Man still bears in his bodily frame the indelible stamp of his lowly origin. MIMICRY AND OTHER PROTECTIVE RESEMBLANCES AMONG ANIMALS ALFRED RUSSEL WALLACE [Mr. Wallace, one of the greatest naturalists of the age, discovered the law of natural selection independently of Darwin, and about the same time. Among his works are "The Malay Archipelago," "Island Life," and "Darwinism." From "Natural Selection," which was published by Macmillan & Co., 1871, the following extracts are taken. The theme has received important development at the hands of Professor E. B. Poulton, in his "The Colours of Animals," International Scientific Series, 1890: and in F. E. Beddard's "Animal Colouration"; London, Swan Sonnenschein; N. Y., Macmillan, 1892.] There is no more convincing proof of the truth of a comprehensive theory, than its power of absorbing and finding a place for new facts, and its capability of interpreting phenomena which had been previously looked upon as unaccountable anomalies. It is thus that the law of universal gravitation and the undulatory theory of light have become established and universally accepted by men of science. Fact after fact has been brought forward as being apparently inconsistent with them, and one after another these very facts have been shown to be the consequences of the laws they were at first supposed to disprove. A false theory will never stand this test. Advancing knowledge brings to light whole groups of facts which it cannot deal with, and its advocates steadily decrease in numbers, notwithstanding the ability and scientific skill with which it has been supported. The course of a true theory is very different, as may be well seen by the progress of opinion on the subject of natural selection. In less than eight years "The Origin of Species" has produced conviction in the minds of a majority of the most eminent living men of science. New facts, new problems, new difficulties as they arise are accepted, solved or removed by this theory; and its principles are illustrated by the progress and conclusions of every well established branch of human knowledge. It is the object of the present essay to show how it has recently been applied to connect together and explain a variety of curious facts which had long been considered as inexplicable anomalies. Perhaps no principle has ever been announced so fertile in results as that which Mr. Darwin so earnestly impresses upon us, and which is indeed a necessary deduction from the theory of natural selection, namely--that none of the definite facts of organic nature, no special organ, no characteristic form or marking, no peculiarities of instinct or of habit, no relations between species or between groups of species--can exist, but which must now be or once have been _useful_ to the individuals or races which possess them. This great principle gives us a clue which we can follow out in the study of many recondite phenomena, and leads us to seek a meaning and a purpose of some definite character in minutiæ which we should be otherwise almost sure to pass over as insignificant or unimportant. The adaptation of the external colouring of animals to their conditions of life has long been recognized, and has been imputed either to an originally created specific peculiarity, or to the direct action of climate, soil, or food. Where the former explanation has been accepted, it has completely checked inquiry, since we could never get any further than the fact of the adaptation. There was nothing more to be known about the matter. The second explanation was soon found to be quite inadequate to deal with all the varied phases of the phenomena, and to be contradicted by many well-known facts. For example, wild rabbits are always of gray or brown tints well suited for concealment among grass and fern. But when these rabbits are domesticated, without any change of climate or food, they vary into white or black, and these varieties may be multiplied to any extent, forming white or black races. Exactly the same thing has occurred with pigeons; and in the case of rats and mice, the white variety has not been shown to be at all dependent on alteration of climate, food or other external conditions. In many cases the wings of an insect not only assume the exact tint of the bark or leaf it is accustomed to rest on, but the form and veining of the leaf or the exact rugosity of the bark is imitated; and these detailed modifications cannot be reasonably imputed to climate or food, since in many cases the species does not feed on the substance it resembles, and when it does, no reasonable connection can be shown to exist between the supposed cause and the effect produced. It was reserved for the theory of natural selection to solve all these problems, and many others which were not at first supposed to be directly connected with them. To make these latter intelligible, it will be necessary to give a sketch of the whole series of phenomena which may be classed under the head of useful or protective resemblances. Concealment, more or less complete, is useful to many animals, and absolutely essential to some. Those which have numerous enemies from which they cannot escape by rapidity of motion, find safety in concealment. Those which prey upon others must also be so constituted as not to alarm them by their presence or their approach, or they would soon die of hunger. Now, it is remarkable in how many cases nature gives this boon to the animal, by colouring it with such tints as may best serve to enable it to escape from its enemies or to entrap its prey. Desert animals as a rule are desert-coloured. The lion is a typical example of this, and must be almost invisible when crouched upon the sand or among desert rocks and stones. Antelopes are all more or less sandy-coloured. The camel is pre-eminently so. The Egyptian cat and the Pampas cat are sandy or earth-coloured. The Australian kangaroos are of the same tints, and the original colour of the wild horse is supposed to have been a sandy or clay-colour. The desert birds are still more remarkably protected by their assimilative hues. The stone-chats, the larks, the quails, the goatsuckers and the grouse, which abound in the North African and Asiatic deserts, are all tinted and mottled so as to resemble with wonderful accuracy the average colour and aspect of the soil in the district they inhabit. The Rev. H. Tristram, in his account of the ornithology of North Africa in the first volume of the "Ibis," says: "In the desert, where neither trees, brushwood, nor even undulation of the surface afford the slightest protection to its foes, a modification of colour which shall be assimilated to that of the surrounding country is absolutely necessary. Hence _without exception_ the upper plumage of _every bird_, whether lark, chat, sylvain, or sand-grouse, and also the fur of _all the smaller mammals_, and the skin of _all the snakes and lizards_, is of one uniform isabelline or sand colour." After the testimony of so able an observer it is unnecessary to adduce further examples of the protective colours of desert animals. Almost equally striking are the cases of arctic animals possessing the white colour that best conceals them upon snowfields and icebergs. The polar bear is the only bear that is white, and it lives constantly among snow and ice. The arctic fox, the ermine and the alpine hare change to white in winter only, because in summer white would be more conspicuous than any other colour, and therefore a danger rather than a protection; but the American polar hare, inhabiting regions of almost perpetual snow, is white all the year round. Other animals inhabiting the same northern regions do not, however, change colour. The sable is a good example, for throughout the severity of a Siberian winter it retains its rich brown fur. But its habits are such that it does not need the protection of colour, for it is said to be able to subsist on fruits and berries in winter, and to be so active upon the trees as to catch small birds among the branches. So also the woodchuck of Canada has a dark-brown fur; but then it lives in burrows and frequents river banks, catching fish and small animals that live in or near the water. Among birds, the ptarmigan is a fine example of protective colouring. Its summer plumage so exactly harmonizes with the lichen-coloured stones among which it delights to sit, that a person may walk through a flock of them without seeing a single bird; while in winter its white plumage is an almost equal protection. The snow-bunting, the jerfalcon, and the snowy owl are also white-coloured birds inhabiting the arctic regions, and there can be little doubt but that their colouring is to some extent protective. Nocturnal animals supply us with equally good illustrations. Mice, rats, bats, and moles possess the least conspicuous of hues, and must be quite invisible at times when any light colour would be instantly seen. Owls and goatsuckers are of those dark mottled tints that will assimilate with bark and lichen, and thus protect them during the day, and at the same time be inconspicuous in the dusk. It is only in the tropics, among forests which never lose their foliage, that we find whole groups of birds whose chief colour is green. The parrots are the most striking example, but we have also a group of green pigeons in the East; and the barbets, leaf-thrushes, bee-eaters, white-eyes, turacos, and several smaller groups, have so much green in their plumage as to tend greatly to conceal them among the foliage. The conformity of tint which has been so far shown to exist between animals and their habitations is of somewhat general character; we will now consider the cases of more special adaptation. If the lion is enabled by his sandy colour readily to conceal himself by merely crouching down in the desert, how, it may be asked, do the elegant markings of the tiger, the jaguar, and the other large cats agree with this theory? We reply that these are generally cases of more or less special adaptation. The tiger is a jungle animal, and hides himself among tufts of grass or of bamboos, and in these positions the vertical stripes with which his body is adorned must so assimilate with the vertical stems of the bamboo, as to assist greatly in concealing him from his approaching prey. How remarkable it is that besides the lion and tiger, almost all the other large cats are arboreal in their habits, and almost all have ocellated or spotted skins, which must certainly tend to blend them with the background of foliage; while the one exception, the puma, has an ashy-brown uniform fur, and has the habit of clinging so closely to a limb of a tree while waiting for his prey to pass beneath as to be hardly distinguishable from the bark. Among birds, the ptarmigan, already mentioned, must be considered a remarkable case of special adaptation. Another is a South American goatsucker (Caprimulgus rupestris) which rests in the bright sunshine on little bare rocky islets in the upper Rio Negro, where its unusually light colours so closely resemble those of the rock and sand, that it can scarcely be detected until trodden upon. The Duke of Argyll, in his "Reign of Law," has pointed out the admirable adaptation of the colours of the woodcock to its protection. The various browns and yellows and pale ash-colour that occur on fallen leaves are all reproduced in its plumage, so that when according to its habit it rests upon the ground under trees, it is almost impossible to detect it. In snipes the colours are modified so as to be equally in harmony with the prevalent forms and colours of marshy vegetation. Mr. J. M. Lester, in a paper read before the Rugby School Natural History Society observes:--"The wood-dove, when perched amongst the branches of its favourite _fir_, is scarcely discernible; whereas, were it among some lighter foliage the blue and purple tints in its plumage would far sooner betray it. The robin redbreast, too, although it might be thought that the red on its breast made it much easier to be seen, is in reality not at all endangered by it, since it generally contrives to get among some russet or yellow fading leaves, where the red matches very well with the autumn tints, and the brown of the rest of the body with the bare branches." Reptiles offer us many similar examples. The most arboreal lizards, the iguanas, are as green as the leaves they feed upon, and the slender whip-snakes are rendered almost invisible as they glide among the foliage by a similar colouration. How difficult it is sometimes to catch sight of the little green tree-frogs sitting on the leaves of a small plant enclosed in a glass case in the Zoological Gardens; yet how much better concealed they must be among the fresh green damp foliage of a marshy forest. There is a North American frog found on lichen-covered rocks and walls, which is so coloured as exactly to resemble them, and as long as it remains quiet would certainly escape detection. Some of the geckos which cling motionless on the trunks of trees in the tropics, are of such curiously marbled colours as to match exactly with the bark they rest upon. In every part of the tropics there are tree snakes that twist among boughs and shrubs, or lie coiled up in the dense masses of foliage. These are of many distinct groups, and comprise both venomous and harmless genera; but almost all of them are of a beautiful green colour, sometimes more or less adorned with white or dusky bands and spots. There can be little doubt that this colour is doubly useful to them, since it will tend to conceal them from their enemies, and will lead their prey to approach them unconscious of danger. Dr. Gunthner informs me that there is only one genus of true arboreal snakes (Dipsas) whose colours are rarely green, but are of various shades of black, brown, and olive, and these are all nocturnal reptiles, and there can be little doubt conceal themselves during the day in holes, so that the green protective tint would be useless to them, and they accordingly retain the more usual reptilian hues. Fishes present similar instances. Many flat fish, as, for example, the flounder and the skate, are exactly the colour of the gravel or sand on which they habitually rest. Among the marine flower gardens of an Eastern coral reef the fishes present every variety of gorgeous colour, while the river fish even of the tropics rarely if ever have gay or conspicuous markings. A very curious case of this kind of adaptation occurs in the sea-horse (Hippocampus) of Australia, some of which bear long foliaceous appendages resembling seaweed, and are of a brilliant red colour; and they are known to live among seaweed of the same hue, so that when at rest they must be quite invisible. There are now in the aquarium of the Zoological Society some slender green pipe-fish which fasten themselves to any object at the bottom by their prehensile tails, and float about with the current, looking exactly like some cylindrical algæ. It is, however, in the insect world that this principle of the adaptation of animals to their environment is most fully and strikingly developed. In order to understand how general this is, it is necessary to enter somewhat into details, as we shall thereby be better able to appreciate the significance of the still more remarkable phenomena we shall presently have to discuss. It seems to be in proportion to their sluggish motions or the absence of other means of defence, that insects possess the protective colouring. In the tropics there are thousands of species of insects which rest during the day clinging to the bark of dead or fallen trees; and the greater portion of these are delicately mottled with gray and brown tints, which though symmetrically disposed and infinitely varied, yet blend so completely with the usual colours of the bark that at two or three feet distance they are quite undistinguishable. In some cases a species is known to frequent only one species of tree. This is the case with the common South American long-horned beetle (Onychocerus scorpio) which, Mr. Bates informed me, is found only on a rough-barked tree, called Tapiriba, on the Amazon. It is very abundant, but so exactly does it resemble the bark in colour and rugosity, and so closely does it cling to the branches, that until it moves it is absolutely invisible! An allied species (O. concentricus) is found only at Para, on a distinct species of tree, the bark of which it resembles with equal accuracy. Both these insects are abundant, and we may fairly conclude that the protection they derive from this strange concealment is at least one of the causes that enable the race to flourish. Many of the species of Cicindela, or tiger beetle, will illustrate this mode of protection. Our common Cicindela campestris frequents grassy banks and is of a beautiful green colour, while C. maritima, which is found only on sandy sea-shores, is of a pale bronzy yellow, so as to be almost invisible. A great number of the species found by myself in the Malay islands are similarly protected. The beautiful Cicindela gloriosa, of a very deep velvety green colour, was only taken upon wet mossy stones in the bed of a mountain stream, where it was with the greatest difficulty detected. A large brown species (C. heros) was found chiefly on dead leaves in forest paths; and one which was never seen except on the wet mud of salt marshes was of a glossy olive so exactly the colour of the mud as only to be distinguished when the sun shone, by its shadow! Where the sandy beach was coralline and nearly white, I found a very pale Cicindela; wherever it was volcanic and black, a dark species of the same genus was sure to be met with. There are in the East small beetles of the family Buprestidæ which generally rest on the midrib of a leaf, and the naturalist often hesitates before picking them off, so closely do they resemble pieces of bird's dung. Kirby and Spence mention the small beetle Onthophilus sulcatus as being like the seed of an umbelliferous plant; and another small weevil, which is much persecuted by predatory beetles of the genus Harpalus, is of the exact colour of loamy soil, and was found to be particularly abundant in loam pits. Mr. Bates mentions a small beetle (Chlamys pilula) which was undistinguishable by the eye from the dung of caterpillars, while some of the Cassidæ, from their hemispherical forms and pearly gold-colour, resemble glittering dew-drops upon the leaves. A number of our small brown and speckled weevils at the approach of any object roll off the leaf they are sitting on, at the same time drawing in their legs and antennæ, which fit so perfectly into cavities for their reception that the insect becomes a mere oval brownish lump, which it is hopeless to look for among the similarly coloured little stones and earth pellets among which it lies motionless. The distribution of colour in butterflies and moths respectively is very instructive from this point of view. The former have all their brilliant colouring on the upper surface of all four wings, while the under surface is almost always soberly coloured, and often very dark and obscure. The moths on the contrary have generally their chief colour on the hind wings only, the upper wings being of dull, sombre, and often imitative tints, and these generally conceal the hind wings when the insects are in repose. This arrangement of the colours is therefore eminently protective, because the butterfly always rests with his wings raised so as to conceal the dangerous brilliancy of his upper surface. It is probable that if we watched their habits sufficiently we should find the under surface of the wings of butterflies very frequently imitative and protective. Mr. T. W. Wood has pointed out that the little orange-tip butterfly often rests in the evening on the green and white flower heads of an umbelliferous plant, and that when observed in this position the beautiful green and white mottling of the under surface completely assimilates with the flower heads and renders the creature very difficult to be seen. It is probable that the rich dark colouring of the under side of our peacock, tortoiseshell, and red-admiral butterflies answers a similar purpose. Two curious South American butterflies that always settle on the trunks of trees (Gynecia dirce and Callizona acesta) have the under surface curiously striped and mottled, and when viewed obliquely must closely assimilate with the appearance of the furrowed bark of many kinds of trees. But the most wonderful and undoubted case of protective resemblance in a butterfly which I have ever seen, is that of the common Indian Kallima inachis, and its Malayan ally, Kallima paralekta. The upper surface of these insects is very striking and showy, as they are of a large size, and are adorned with a broad band of rich orange on a deep bluish ground. The under side is very variable in colour, so that out of fifty specimens no two can be found exactly alike, but every one of them will be of some shade of ash or brown or ochre, such as are found among dead, dry or decaying leaves. The apex of the upper wings is produced into an acute point, a very common form in the leaves of tropical shrubs and trees, and the lower wings are also produced into a short, narrow tail. Between these two points runs a dark curved line exactly representing the midrib of a leaf, and from this radiate on each side a few oblique lines, which serve to indicate the lateral veins of a leaf. These marks are more clearly seen on the outer portion of the base of the wings, and on the inner side towards the middle and apex, and it is very curious to observe how the usual marginal and transverse striæ of the group are here modified and strengthened so as to become adapted for an imitation of the venation of a leaf. We come now to a still more extraordinary part of the imitation, for we find representations of leaves in every stage of decay, variously blotched and mildewed and pierced with powdery black dots gathered into patches and spots, so closely resembling the various kinds of minute fungi that grow on dead leaves that is it impossible to avoid thinking at first sight that the butterflies themselves have been attacked by real fungi. But this resemblance, close as it is, would be little use if the habits of the insect did not accord with it. If the butterfly sat upon leaves or upon flowers, or opened its wings so as to expose the upper surface, or exposed and moved its head and antennæ as many other butterflies do, its disguise would be of little avail. We might be sure, however, from the analogy of many other cases, that the habits of the insect are such as still further to aid its deceptive garb; but we are not obliged to make any such supposition, since I myself had the good fortune to observe scores of Kallima paralekta, in Sumatra, and to capture many of them, and can vouch for the accuracy of the following details: These butterflies frequent dry forests and fly very swiftly. They were never seen to settle on a flower or a green leaf, but were many times lost sight of in a bush or tree of dead leaves. On such occasions they were generally searched for in vain, for while gazing intently at the very spot where one had disappeared, it would often suddenly dart out and again vanish twenty or fifty yards further on. On one or two occasions the insect was detected reposing, and it could then be seen how completely it assimilates itself to the surrounding leaves. It sits on a nearly upright twig, the wings fitting closely back to back, concealing the antennæ and head, which are drawn up between their bases. The little tails of the hind wings touch the branch and form a perfect stalk to the leaf, which is supported in its place by the claws of the middle pair of feet, which are slender and inconspicuous. The irregular outline of the wings gives exactly the perspective effect of a shrivelled leaf. We thus have size, colour, form, markings, and habits, all combining together to produce a disguise which may be said to be absolutely perfect; and the protection which it affords is sufficiently indicated by the abundance of the individuals that possess it.... We will now endeavour to show how these wonderful resemblances have most probably been brought about. Returning to the higher animals, let us consider the remarkable fact of the rarity of white colouring in the mammalia or birds of the temperate or tropical zones in a state of nature. There is not a single white land-bird or quadruped in Europe, except the few arctic or alpine species to which white is a protective colour. Yet in many of these creatures there seems to be no inherent tendency to avoid white, for directly they are domesticated white varieties arise, and appear to thrive as well as others. We have white mice and rats, white cats, horses, dogs, and cattle, white poultry, pigeons, turkeys, and ducks, and white rabbits. Some of these animals have been domesticated for a long period, others only for a few centuries; but in almost every case in which an animal has been thoroughly domesticated, parti-coloured and white varieties are produced and become permanent. It is also well known that animals in a state of nature produce white varieties occasionally. Blackbirds, starlings, and crows are occasionally seen white, as well as elephants, deer, tigers, hares, moles, and many other animals; but in no case is a permanent white race produced. Now there are no statistics to show that the normal-coloured parents produce white offspring oftener under domestication than in a state of nature, and we have no right to make such an assumption if the facts can be accounted for without it. But if the colours of animals do really, in the various instances already adduced, serve for their concealment and preservation, then white or any other conspicuous colour must be hurtful, and must in most cases shorten an animal's life. A white rabbit would be more surely the prey of hawk or buzzard, and the white mole, or field mouse, could not long escape from the vigilant owl. So, also, any deviation from those tints best adapted to conceal a carnivorous animal would render the pursuit of its prey much more difficult, would place it at a disadvantage among its fellows and in a time of scarcity would probably cause it to starve to death. On the other hand, if an animal spreads from a temperate into an arctic district, the conditions are changed. During a large portion of the year, and just when the struggle for existence is most severe, white is the prevailing tint of nature, and dark colours will be the most conspicuous. The white varieties will now have an advantage; they will escape from their enemies or will secure food, while their brown companions will be devoured or will starve; and "as like produces like" is the established rule in nature, the white race will become permanently established, and dark varieties, when they occasionally appear, will soon die out from their want of adaptation to their environment. In each case the fittest will survive, and a race will be eventually produced adapted to the conditions in which it lives. We have here an illustration of the simple and effectual means by which animals are brought into harmony with the rest of nature. That slight amount of variability in every species, which we often look upon as something accidental or abnormal, or so insignificant as to be hardly worthy of notice, is yet the foundation of all those wonderful and harmonious resemblances which play such an important part in the economy of nature. Variation is generally very small in amount, but it is all that is required, because the change in the external conditions to which an animal is subject is generally very slow and intermittent. When these changes have taken place too rapidly, the result has often been the extinction of species; but the general rule is, that climatal and geological changes go on slowly, and the slight but continual variations in the colour, form and structure of all animals, has furnished individuals adapted to these changes, and who have become the progenitors of modified races. Rapid multiplication, incessant slight variation, and survival of the fittest--these are the laws which ever keep the organic world in harmony with the inorganic and with itself. These are the laws which we believe have produced all the cases of protective resemblance already adduced, as well as those still more curious examples we have yet to bring before our readers. It must always be borne in mind that the more wonderful examples, in which there is not only a general but a special resemblance as in the walking leaf, the mossy phasma, and the leaf-winged butterfly--represent those few instances in which the process of modification has been going on during an immense series of generations. They all occur in the tropics, where the conditions of existence are the most favourable, and where climatic changes have for long periods been hardly perceptible. In most of them favourable variations both of colour, form, structure, and instinct or habit, must have occurred to produce the perfect adaptation we now behold. All these are known to vary, and favourable variations when not accompanied by others that are unfavourable, would certainly survive. At one time a little step might be made in this direction, at another time in that--a change of conditions might sometimes render useless that which it had taken ages to produce--great and sudden physical modifications might often produce the extinction of a race just as it was approaching perfection, and a hundred checks of which we can know nothing may have retarded the progress towards perfect adaptation; so that we can hardly wonder at there being so few cases in which a completely successful result has been attained as shown by the abundance and wide diffusion of the creatures so protected. [Here are given many detailed examples of insects which gainfully mimic one another.] We will now adduce a few cases in which beetles imitate other insects, and insects of other orders imitate beetles. Charis melipona, a South American Longicorn of the family Necydalidæ, has been so named from its resemblance to a small bee of the genus Melipona. It is one of the most remarkable cases of mimicry, since the beetle has the thorax and body densely hairy like the bee, and the legs are tufted in a manner most unusual in the order Coleoptera. Another Longicorn, Odontocera odyneroides, has the abdomen banded with yellow, and constricted at the base, and is altogether so exactly like a small common wasp of the genus Odynerus, that Mr. Bates informs us he was afraid to take it out of his net with his fingers for fear of being stung. Had Mr. Bates's taste for insects been less omnivorous than it was, the beetle's disguise might have saved it from his pin, as it had no doubt often done from the beak of hungry birds. A larger insect, Sphecomorpha chalybea, is exactly like one of the large metallic blue wasps, and like them has the abdomen connected with the thorax by a pedicle, rendering the deception most complete and striking. Many Eastern species of Longicorns of the genus Oberea, when on the wing exactly resemble Tenthredinidæ, and many of the small species of Hesthesis run about on timber, and cannot be distinguished from ants. There is one genus of South American Longicorns that appears to mimic the shielded bugs of the genus Scutellera. The Gymnocerous capucinus is one of these, and is very like Pachyotris fabricii, one of the Scutelleridæ. The beautiful Gymnocerous dulcissimus is also very like the same group of insects, though there is no known species that exactly corresponds to it; but this is not to be wondered at, as the tropical Hemiptera have been comparatively so little cared for by collectors. The most remarkable case of an insect of another order mimicking a beetle is that of the Condylodera tricondyloides, one of the cricket family from the Philippine Islands, which is so exactly like a Tricondyla (one of the tiger beetles), that such an experienced entomologist as Professor Westwood placed it among them in his cabinet, and retained it there a long time before he discovered his mistake! Both insects run along the trunks of trees, and whereas Tricondylas are very plentiful, the insect that mimics it is, as in all other cases, very rare. Mr. Bates also informs us that he found at Santarem on the Amazon, a species of locust which mimicked one of the tiger beetles of the genus Odontocheila, and was found on the same trees which they frequented. There are a considerable number of Diptera, or two-winged flies, that closely resemble wasps and bees, and no doubt derive much benefit from the wholesome dread which those insects excite. The Midas dives, and other species of large Brazilian flies, have dark wings and metallic blue elongate bodies, resembling the large stinging Sphegidæ of the same country; and a very large fly of the genus Asilus has black-banded wings and the abdomen tipped with rich orange, so as exactly to resemble the fine bee Euglossa dimidiata, and both are found in the same parts of South America. We have also in our own country species of Bombylius which are almost exactly like bees. In these cases the end gained by the mimicry is no doubt freedom from attack, but it has sometimes an altogether different purpose. There are a number of parasitic flies whose larvæ feed upon the larvæ of bees, such as the British genus Volucella and many of the tropical Bombylii, and most of these are exactly like the particular species of bee they prey upon, so that they can enter their nests unsuspected to deposit their eggs. There are also bees that mimic bees. The cuckoo bees of the genus Nomada are parasitic on the Andrenidæ, and they resemble either wasps or species of Andrena; and the parasitic humble-bees of the genus Apathus almost exactly resemble the species of humble-bees in whose nests they are reared. Mr. Bates informs us that he found numbers of these "cuckoo" bees and flies on the Amazon, which all wore the livery of working bees peculiar to the same country. There is a genus of small spiders in the tropics which feed on ants, and they are exactly like ants themselves, which no doubt gives them more opportunity of seizing their prey; and Mr. Bates found on the Amazon a species of Mantis which exactly resembled the white ants which it fed upon, as well as several species of crickets (Saphura), which resembled in a wonderful manner different sand-wasps of large size, which are constantly on the search for crickets with which to provision their nests. Perhaps the most wonderful case of all is the large caterpillar mentioned by Mr. Bates, which startled him by its close resemblance to a small snake. The first three segments behind the head were dilatable at the will of the insect, and had on each side a large black pupillated spot, which resembled the eye of the reptile. Moreover, it resembled a poisonous viper, not a harmless species of snake, as was proved by the imitation of keeled scales on the crown produced by the recumbent feet, as the caterpillar threw itself backward! The attitudes of many of the tropical spiders are most extraordinary and deceptive, but little attention has been paid to them. They often mimic other insects, and some, Mr. Bates assures us, are exactly like flower buds, and take their station in the axils of leaves, where they remain motionless waiting for their prey. I have now completed a brief, and necessarily very imperfect, survey of the various ways in which the external form and colouring of animals is adapted to be useful to them, either by concealing them from their enemies or from the creatures they prey upon. It has, I hope, been shown that the subject is one of much interest, both as regard a true comprehension of the place each animal fills in the economy of nature, and the means by which it is enabled to maintain that place; and also as teaching us how important a part is played by the minutest details in the structure of animals, and how complicated and delicate is the equilibrium of the organic world. My exposition of the subject having been necessarily somewhat lengthy and full of details, it will be as well to recapitulate its main points. There is a general harmony in nature between the colours of an animal and those of its habitation. Arctic animals are white, desert animals are sand-coloured; dwellers among leaves and grass are green; nocturnal animals are dusky. These colours are not universal, but are very general, and are seldom reversed. Going on a little further, we find birds, reptiles and insects, so tinted and mottled as exactly to match the rock, or bark, or leaf, or flower they are accustomed to rest upon--and thereby effectually concealed. Another step in advance, and we have insects which are formed as well as coloured so as exactly to resemble particular leaves, or sticks, or mossy twigs, or flowers; and in these cases very peculiar habits and instincts come into play to aid in the deception and render the concealment more complete. We now enter upon a new phase of the phenomena, and come to creatures whose colours neither conceal them nor make them like vegetable or mineral substances; on the contrary, they are conspicuous enough, but they completely resemble some other creature of a quite different group, while they differ much in outward appearance from those with which all essential parts of their organization show them to be really closely allied. They appear like actors or masqueraders dressed up and painted for amusement, or like swindlers endeavouring to pass themselves off for well-known and respectable members of society. What is the meaning of this strange travesty? Does nature descend to imposture or masquerade? We answer, she does not. Her principles are too severe. There is a use in every detail of her handiwork. The resemblance of one animal to another is of exactly the same essential nature as the resemblance to a leaf, or to bark, or to desert sand, and answers exactly the same purpose. In the one case the enemy will not attack the leaf or the bark, and so the disguise is a safeguard; in the other case it is found that for various reasons the creature resembled is passed over, and not attacked by the usual enemies of its order, and thus the creature that resembles it has an equally effectual safeguard. We are plainly shown that the disguise is of the same nature in the two cases, by the occurrence in the same group of one species resembling a vegetable substance, while another resembles a living animal of another group; and we know that the creatures resembled possess an immunity from attack, by their being always very abundant, by their being conspicuous and not concealing themselves, and by their having generally no visible means of escape from their enemies; while, at the same time, the particular quality that makes them disliked is often very clear, such as a nasty taste or an indigestible hardness. Further examination reveals the fact that, in several cases of both kinds of disguise, it is the female only that is thus disguised; and as it can be shown that the female needs protection much more than the male, and that her preservation for a much longer period is absolutely necessary for the continuance of the race, we have an additional indication that the resemblance is in all cases subservient to a great purpose--the preservation of the species. In endeavouring to explain these phenomena as having been brought about by variation and natural selection, we start with the fact that white varieties frequently occur, and when protected from enemies show no incapacity for continued existence and increase. We know, further, that varieties of many other tints occasionally occur; and as "the survival of the fittest" must inevitably weed out those whose colours are prejudicial and preserve those whose colours are a safeguard, we require no other mode of accounting for the protective tints of arctic and desert animals. But this being granted, there is such a perfectly continuous and graduated series of examples of every kind of protective imitation, up to the most wonderful cases of what is termed "mimicry," that we can find no place at which to draw the line and say,--so far variation and natural selection will account for the phenomena, but for all the rest we require a more potent cause. The counter theories that have been proposed, that of the "special creation" of each imitative form, that of the action of similar "conditions of existence" for some of the cases, and of the laws of "hereditary descent and the reversion to ancestral forms" for others,--have all been shown to be beset with difficulties, and the two latter to be directly contradicted by some of the most constant and most remarkable of the facts to be accounted for. The important part that protective "resemblance" has played in determining the colours and markings of many groups of animals will enable us to understand the meaning of one of the most striking facts in nature, the uniformity in the colours of the vegetable as compared with the wonderful diversity of the animal world. There appears no good reason why trees and shrubs should not have been adorned with as many varied hues and as strikingly designed patterns as birds and butterflies, since the gay colours of flowers show that there is no incapacity in vegetable tissues to exhibit them. But even flowers themselves present us with none of those wonderful designs, those complicated arrangements of stripes and dots and patches of colour, that harmonious blending of hues in lines and bands and shaded spots, which are so general a feature in insects. It is the opinion of Mr. Darwin that we owe much of the beauty of flowers to the necessity of attracting insects to aid in their fertilization, and that much of the development of colour in the animal world is due to "sexual selection," colour being universally attractive, and thus leading to its propagation and increase; but while fully admitting this, it will be evident from the facts and arguments here brought forward, that very much of the _variety_ both of colour and markings among animals is due to the supreme importance of concealment, and thus the various tints of minerals and vegetables have been directly reproduced in the animal kingdom, and again and again modified as more special protection became necessary. We shall thus have two causes for the development of colour in the animal world and shall be better enabled to understand how, by their combined and separate action, the immense variety we now behold has been produced. Both causes, however, will come under the general law of "Utility," the advocacy of which, in its broadest sense, we owe almost entirely to Mr. Darwin. A more accurate knowledge of the varied phenomena connected with this subject may not improbably give us some information both as to the senses and the mental faculties of the lower animals. For it is evident that if colours which please us also attract them, and if the various disguises which have been here enumerated are equally deceptive to them as to ourselves, then both their powers of vision and their faculties of perception and emotion, must be essentially of the same nature as our own--a fact of high philosophical importance in the study of our own nature and our true relations to the lower animals.[4] FOOTNOTES: [4] The author continues this study in Chapter ix of "Darwinism": New York, Macmillan Co., 1889.--Ed. THE EVOLUTION OF THE HORSE THOMAS HENRY HUXLEY [Professor Huxley as a naturalist, educator, and controversialist was one of the commanding figures of the nineteenth century. To physiology and morphology his researches added much of importance: as an expositor he stood unapproached. As the bold and witty champion of Darwinism he gave natural selection an acceptance much more early and wide than it would otherwise have enjoyed. In 1876 he delivered in America three lectures on Evolution: the third of the series is here given. All three are copyrighted and published by D. Appleton & Co., New York, in a volume which also contains a lecture on the study of biology. Since 1876 the arguments of Professor Huxley have been reinforced by the discovery of many fossils connecting not only the horse, but other quadrupeds, with species widely different and now extinct. The most comprehensive collection illustrating the descent of the horse is to be seen at the American Museum of Natural History, New York, where also the evolution of tapirs, camels, llamas, rhinoceroses, dinosaurs, great ground sloths and other animals are clearly to be traced--in most cases by remains discovered in America. A capital book on the theme broached by Professor Huxley is "Animals of the Past," by Frederic A. Lucas, Curator of the Division of Comparative Anatomy, United States National Museum, Washington, D. C., published by McClure, Phillips & Co., New York. "The Life and Letters of Professor Huxley," edited by his son, Leonard Huxley, is a work of rare interest: it is published by D. Appleton & Co., New York.] The occurrence of historical facts is said to be demonstrated, when the evidence that they happened is of such a character as to render the assumption that they did not happen in the highest degree improbable; and the question I now have to deal with is, whether evidence in favour of the evolution of animals of this degree of cogency is, or is not, obtainable from the record of the succession of living forms which is presented to us by fossil remains. Those who have attended to the progress of palæontology are aware that evidence of the character which I have defined has been produced in considerable and continually-increasing quantity during the last few years. Indeed, the amount and the satisfactory nature of that evidence are somewhat surprising, when we consider the conditions under which alone we can hope to obtain it. It is obviously useless to seek for such evidence, except in localities in which the physical conditions have been such as to permit of the deposit of an unbroken, or but rarely interrupted, series of strata through a long period of time; in which the group of animals to be investigated has existed in such abundance as to furnish the requisite supply of remains; and in which, finally, the materials composing the strata are such as to insure the preservation of these remains in a tolerably perfect and undisturbed state. It so happens that the case which, at present, most nearly fulfils all these conditions is that of the series of extinct animals which culminates in the horses; by which term I mean to denote not merely the domestic animals with which we are all so well acquainted, but their allies, the ass, zebra, quagga, and the like. In short, I use "horses" as the equivalent of the technical name _Equidæ_, which is applied to the whole group of existing equine animals. The horse is in many ways a remarkable animal; not least so in the fact that it presents us with an example of one of the most perfect pieces of machinery in the living world. In truth, among the works of human ingenuity it cannot be said that there is any locomotive so perfectly adapted to its purposes, doing so much work with so small a quantity of fuel, as this machine of nature's manufacture--the horse. And, as a necessary consequence of any sort of perfection, of mechanical perfection as of others, you find that the horse is a beautiful creature, one of the most beautiful of all land animals. Look at the perfect balance of its form, and the rhythm and force of its action. The locomotive machinery is, as you are aware, resident in its slender fore and hind limbs; they are flexible and elastic levers, capable of being moved by very powerful muscles; and, in order to supply the engines which work these levers with the force which they expend, the horse is provided with a very perfect apparatus for grinding its food and extracting therefrom the requisite fuel. Without attempting to take you very far into the region of osteological detail, I must nevertheless trouble you with some statements respecting the anatomical structure of the horse; and, more especially, will it be needful to obtain a general conception of the structure of its fore and hind limbs, and of its teeth. But I shall only touch upon these points which are absolutely essential to our inquiry. Let us turn in the first place to the fore-limb. In most quadrupeds, as in ourselves, the fore-arms contains distinct bones called the radius and the ulna. The corresponding region in the horse seem at first to possess but one bone. Careful observation, however, enables us to distinguish in this bone a part which clearly answers to the upper end of the ulna. This is closely united with the chief mass of the bone which represents the radius, and runs out into a slender shaft which may be traced for some distance downwards upon the back of the radius, and then in most cases thins out and vanishes. It takes still more trouble to make sure of what is nevertheless the fact, that a small part of the lower end of the bone of the horse's fore-arm, which is only distinct in a very young foal, is really the lower extremity of the ulna. What is commonly called the knee of a horse is its wrist. The "cannon bone" answers to the middle bone of the five metacarpal bones, which support the palm of the hand in ourselves. The "pastern," "coronary," and "coffin" bones of veterinarians answer to the joints of our middle fingers, while the hoof is simply a greatly enlarged and thickened nail. But if what lies below the horse's "knee" thus corresponds to the middle finger in ourselves, what has become of the four other fingers or digits? We find in the places of the second and fourth digits only two slender splint-like bones, about two-thirds as long as the cannon bone, which gradually taper to their lower ends and bear no finger joints, or, as they are termed, phalanges. Sometimes, small bony or gristly nodules are to be found at the bases of these two metacarpal splints, and it is probable that these represent rudiments of the first and fifth toes. Thus, the part of the horse's skeleton, which corresponds with that of the human hand, contains one overgrown middle digit, and at least two imperfect lateral digits; and these answer, respectively, to the third, the second and the fourth fingers in man. Corresponding modifications are found in the hind limb. In ourselves, and in most quadrupeds, the leg contains two distinct bones, a large bone, the tibia, and a smaller and more slender bone, the fibula. But, in the horse, the fibula seems, at first, to be reduced to its upper end; a short slender bone united with the tibia and ending in a point below, occupying its place. Examination of the lower end of a young foal's shin-bone, however, shows a distinct portion of osseous matter, which is the lower end of the fibula; so that the, apparently single, lower end of the shin-bone is really made up of the coalesced ends of the tibia and fibula, just as the, apparently single, lower end of the fore-arm bone is composed of the coalesced radius and ulna. The heel of the horse is the part commonly known as the hock. The hinder cannon bone answers to the middle metatarsal bone of the human foot, the pastern, coronary, and coffin bones, to the middle toe bones; the hind hoof to the nail; as in the fore-foot. And, as in the fore-foot, there are merely two splints to represent the second and the fourth toes. Sometimes a rudiment of a fifth toe appears to be traceable. The teeth of a horse are not less peculiar than its limbs. The living engine, like all others, must be well stoked if it is to do its work; and the horse, if it is to make good its wear and tear, and to exert the enormous amount of force required for its propulsion, must be well and rapidly fed. To this end good cutting instruments and powerful and lasting crushers are needful. Accordingly, the twelve cutting teeth of a horse are close-set and concentrated in the fore-part of its mouth, like so many adzes or chisels. The grinders or molars are large, and have an extremely complicated structure, being composed of a number of different substances of unequal hardness. The consequence of this is that they wear away at different rates; and, hence, the surface of each grinder is always as uneven as that of a good millstone. I have said that the structure of the grinding teeth is very complicated, the harder and the softer parts being, as it were, interlaced with one another. The result of this is that, as the tooth wears, the crown presents a peculiar pattern, the nature of which is not very easily deciphered at first, but which it is important we should understand clearly. Each grinding tooth of the upper jaw has an _outer wall_ so shaped that, on the worn crown, it exhibits the form of two crescents, one in front and one behind, with their concave sides turned outwards. From the inner side of the front crescent, a crescentic _front ridge_ passes inwards and backwards, and its inner face enlarges into a strong longitudinal fold or _pillar_. From the front part of the hinder crescent, a _back ridge_ takes a like direction, and also has its _pillar_. The deep interspaces or _valleys_ between these ridges and the outer wall are filled by bony substance, which is called _cement_, and coats the whole tooth. The pattern of the worn face of each grinding tooth of the lower jaw is quite different. It appears to be formed of two crescent-shaped ridges, the convexities of which are turned outwards. The free extremity of each crescent has a _pillar_, and there is a large double _pillar_ where the two crescents meet. The whole structure is, as it were, imbedded in cement, which fills up the valleys, as in the upper grinders. If the grinding faces of an upper and of a lower molar of the same side are applied together, it will be seen that the opposed ridges are nowhere parallel, but that they frequently cross; and that thus, in the act of mastication, a hard surface in the one is constantly applied to a soft surface in the other, and _vice versa_. They thus constitute a grinding apparatus of great efficiency, and one which is repaired as fast as it wears, owing to the long-continued growth of the teeth. Some other peculiarities of the dentition of the horse must be noticed, as they bear upon what I shall have to say by and by. Thus the crowns of the cutting teeth have a peculiar deep pit, which gives rise to the well-known "mark" of the horse. There is a large space between the outer incisors and the front grinders. In this space the adult male horse presents, near the incisors on each side, above and below, a canine or "tush," which is commonly absent in mares. In a young horse, moreover, there is not unfrequently to be seen, in front of the first grinder, a very small tooth, which soon falls out. If this small tooth be counted as one, it will be found that there are seven teeth behind the canine on each side; namely, the small tooth in question, and the six great grinders, among which, by an unusual peculiarity, the foremost tooth is rather larger than those which follow it. I have now enumerated those characteristic structures of the horse which are of most importance for the purpose we have in view. To any one who is acquainted with the morphology [comparative forms] of vertebrated animals, they show that the horse deviates widely from the general structure of mammals; and that the horse type is, in many respects, an extreme modification of the general mammalian plan. The least modified mammals, in fact, have the radius and ulna, the tibia and fibula, distinct and separate. They have five distinct and complete digits on each foot, and no one of these digits is very much larger than the rest. Moreover, in the least modified mammals the total number of the teeth is very generally forty-four, while in horses the usual number is forty, and in the absence of the canines it may be reduced to thirty-six; the incisor teeth are devoid of the fold seen in those of the horse: the grinders regularly diminish in size from the middle of the series to its front end; while their crowns are short, early attain their full length, and exhibit simple ridges or tubercles, in place of the complex foldings of the horse's grinders. Hence the general principles of the hypothesis of evolution lead to the conclusion that the horse must have been derived from some quadruped which possessed five complete digits on each foot; which had the bones of the fore-arm and of the leg complete and separate; and which possessed forty-four teeth, among which the crowns of the incisors and grinders had a simple structure; while the latter gradually increased in size from before backwards, at any rate in the anterior part of the series, and had short crowns. And if the horse has been thus evolved, and the remains of the different stages of its evolution have been preserved, they ought to present us with a series of forms in which the number of the digits becomes reduced; the bones of the fore-arm and leg gradually take on the equine condition; and the form and arrangement of the teeth successively approximate to those which obtain in existing horses. Let us turn to the facts, and see how far they fulfil these requirements of the doctrine of evolution. In Europe abundant remains of horses are found in the Quaternary and later Tertiary strata as far as the Pliocene formation. But these horses, which are so common in the cave-deposits and in the gravels of Europe, are in all essential respects like existing horses. And that is true of all the horses of the latter part of the Pliocene epoch. But in deposits which belong to the earlier Pliocene and later Miocene epochs, and which occur in Britain, in France, in Germany, in Greece, in India, we find animals which are extremely like horses--which, in fact, are so similar to horses that you may follow descriptions given in works upon the anatomy of the horse upon the skeletons of these animals--but which differ in some important particulars. For example, the structure of their fore and hind limbs is somewhat different. The bones which, in the horse, are represented by two splints, imperfect below, are as long as the middle metacarpal and metatarsal bones; and attached to the extremity of each is a digit with three joints of the same general character as those of the middle digit, only very much smaller. These small digits are so disposed that they could have had but very little functional importance, and they must have been rather of the nature of the dew-claws, such as are to be found in many ruminant animals. The _Hipparion_, as the extinct European three-toed horse is called, in fact, presents a foot similar to that of the American _Protohippus_ (Fig. 9), except that in the _Hipparion_ the smaller digits are situated farther back and are of smaller proportional size than in the _Protohippus_. The ulna is slightly more distinct than in the horse; and the whole length of it, as a very slender shaft intimately united with the radius, is completely traceable. The fibula appears to be in the same condition as in the horse. The teeth of the _Hipparion_ are essentially similar to those of the horse, but the pattern of the grinders is in some respects a little more complex, and there is a depression on the face of the skull in front of the orbit, which is not seen in existing horses. In the earlier Miocene, and perhaps the later Eocene deposits of some parts of Europe, another extinct animal has been discovered, which Cuvier, who first described some fragments of it, considered to be a _Palæotherium_. But as further discoveries threw new light on its structure, it was recognized as a distinct genus under the name of _Anchitherium_. In its general characters, the skeleton of _Anchitherium_ is very similar to that of the horse. In fact, Lartet and De Blainville called it _Palæotherium equinum_ or _hippoides_; and De Christol, in 1847, said that it differed from _Hipparion_ in little more than the characters of its teeth, and gave it the name of _Hipparitherium_. Each foot possesses three complete toes; while the lateral toes are much larger in proportion to the middle toe than in _Hipparion_, and doubtless rested on the ground in ordinary locomotion. The ulna is complete and quite distinct from that radius, though firmly united with the latter. The fibula seems also to have been complete. Its lower end, though intimately united with that of the tibia, is clearly marked off from the latter bone. There are forty-four teeth. The incisors have no strong pit. The canines seem to have been well developed in both sexes. The first of the seven grinders, which, as I have said, is frequently absent, and when it does exist, is small in the horse, is a good-sized and permanent tooth, while the grinder which follows it is but little larger than the hinder ones. The crowns of the grinders are short, and though the fundamental pattern of the horse-tooth is discernible, the front and back ridges are less curved, the accessory pillars, are wanting, and the valleys, much shallower, are not filled up with cement. Seven years ago, when I happened to be looking critically into the bearing of palæontological facts upon the doctrine of evolution, it appeared to me that the _Anchitherium_, the _Hipparion_, and the modern horses, constitute a series in which the modifications of structure coincide with the order of chronological occurrence, in the manner in which they must coincide, if the modern horses really are the result of the gradual metamorphosis, in the course of the Tertiary epoch, of a less specialized ancestral form. And I found by correspondence with the late eminent French anatomist and palæontologist, M. Lartet, that he had arrived at the same conclusion from the same data. That the _Anchitherium_ type had become metamorphosed into the _Hipparion_ type, and the latter into the _Equine_ type,[5] in the course of that period of time which is represented by the latter half of the Tertiary deposits, seemed to me to be the only explanation of the facts for which there was even a shadow of probability. And, hence, I have ever since held that these facts afford evidence of the occurrence of evolution, which, in the sense already defined, may be termed demonstrative. All who have occupied themselves with the structure of _Anchitherium_, from Cuvier onwards, have acknowledged its many points of likeness to a well-known genus of extinct Eocene mammals, _Palæotherium_. Indeed, as we have seen, Cuvier regarded his remains of _Anchitherium_ as those of a species of _Palæotherium_. Hence, in attempting to trace the pedigree of the horse beyond the Miocene epoch and the Anchitheroid form, I naturally sought among the various species of Palæotheroid animals for its nearest ally, and I was led to the conclusion that the _Palæotherium minus_ (_Plagiolophus_) represented the next step more nearly than any form then known. I think that this opinion was fully justifiable; but the progress of investigation has thrown an unexpected light on the question, and has brought us much nearer than could have been anticipated to a knowledge of the true series of the progenitors of the horse. You are all aware that, when your country was first discovered by Europeans, there were no traces of the existence of the horse on any part of the American Continent. The accounts of the conquest of Mexico dwell upon the astonishment of the natives of that country when they first became acquainted with that astounding phenomenon--a man seated upon a horse. Nevertheless, the investigations of American geologists have proved that the remains of horses occur in the most superficial deposits of both North and South America, just as they do in Europe. Therefore, for some reason or other--no feasible suggestion on that subject, so far as I know, has been made--the horse must have died out on this continent at some period preceding the discovery of America. Of late years there has been discovered in your Western Territories that marvellous accumulation of deposits, admirably adapted for the preservation of organic remains, to which I referred the other evening, and which furnishes us with a consecutive series of records of the fauna of the older half of the Tertiary epoch, for which we have no parallel in Europe. They have yielded fossils in an excellent state of conservation and in unexampled numbers and variety. The researches of Leidy and others have shown that forms allied to the _Hipparion_ and the _Anchitherium_ are to be found among these remains. But it is only recently that the admirably conceived and most thoroughly and patiently worked-out investigations of Professor Marsh have given us a just idea of the vast fossil wealth, and of the scientific importance, of these deposits. I have had the advantage of glancing over the collections in Yale Museum; and I can truly say, that so far as my knowledge extends, there is no collection from any one region and series of strata comparable, for extent, or for the care with which the remains have been got together, or for their scientific importance, to the series of fossils which he has deposited there. This vast collection has yielded evidence bearing upon the question of the pedigree of the horse of the most striking character. It tends to show that we must look to America, rather than to Europe, for the original seat of the equine series; and that the archaic forms and successive modifications of the horse's ancestry are far better preserved here than in Europe. Professor Marsh's kindness has enabled me to put before you a diagram, every figure of which is an actual representation of some specimen which is to be seen at Yale at this present time (Fig. 9). The succession of forms which he has brought together carries us from the top to the bottom of the Tertiaries. Firstly, there is the true horse. Next we have the American Pliocene form of the horse (_Pliohippus_); in the conformation of its limbs it presents some very slight deviations from the ordinary horse, and the crowns of the grinding teeth are shorter. Then comes the _Protohippus_, which represents the European _Hipparion_, having one large digit and two small ones on each foot, and the general characters of the fore-arm and leg to which I have referred. But it is more valuable than the European _Hipparion_ for the reason that it is devoid of some of the peculiarities of that form--peculiarities which tend to show that the European _Hipparion_ is rather a member of a collateral branch, than a form in the direct line of succession. Next, in the backward order in time, is the _Miohippus_, which corresponds pretty nearly with the _Anchitherium_ of Europe. It presents three complete toes--one large median and two smaller lateral ones; and there is a rudiment of that digit, which answers to the little finger of the human hand. The European record of the pedigree of the horse stops here; in the American Tertiaries, on the contrary, the series of ancestral equine forms is continued into the Eocene formations. An older Miocene form, termed _Mesohippus_, has three toes in front, with a large splint-like rudiment representing the little finger; and three toes behind. The radius and ulna, the tibia and the fibula, are distinct, and the short crowned molar teeth are anchitheroid in pattern. But the most important discovery of all is the _Orohippus_, which comes from the Eocene formation, and which is the oldest member of the equine series, as yet known. Here we find four complete toes on the front-limb, three toes on the hind-limb, a well-developed ulna, a well-developed fibula, and short-crowned grinders of simple pattern. Thus, thanks to these important researches, it has become evident that, so far as our present knowledge extends, the history of the horse-type is exactly and precisely that which could have been predicted from a knowledge of the principles of evolution. And the knowledge we now possess justifies us completely in the anticipation, that when the still lower Eocene deposits, and those which belong to the Cretaceous epoch, have yielded up their remains of ancestral equine animals, we shall find, first, a form with four complete toes and a rudiment of the innermost or first digit in front, with probably, a rudiment of the fifth digit in the hind foot;[6] while, in still older forms, the series of the digits will be more and more complete, until we come to the five-toed animals, in which, if the doctrine of evolution is well founded, the whole series must have taken its origin. That is what I mean by demonstrative evidence of evolution. An inductive hypothesis is said to be demonstrated when the facts are shown to be in entire accordance with it. If that is not scientific proof, there are no merely inductive conclusions which can be said to be proved. And the doctrine of evolution, at the present time, rests upon exactly as secure a foundation as the Copernican theory of the motions of the heavenly bodies did at the time of its promulgation. Its logical basis is precisely of the same character--the coincidence of the observed facts with theoretical requirements. The only way of escape, if it be a way of escape, from the conclusions which I have just indicated, is the supposition that all these different equine forms have been created separately at separate epochs of time; and, I repeat, that of such an hypothesis as this there neither is, nor can be, any scientific evidence; and, assuredly, so far as I know, there is none which is supported, or pretends to be supported, by evidence or authority of any other kind. I can but think that the time will come when such suggestions as these, such obvious attempts to escape the force of demonstration, will be put upon the same footing as the supposition made by some writers, who are, I believe, not completely extinct at present, that fossils are mere simulacra [images], are no indications of the former existence of the animals to which they seem to belong; but that they are either sports of Nature, or special creations, intended--as I heard suggested the other day--to test our faith. In fact, the whole evidence is in favour of evolution, and there is none against it. And I say this, although perfectly well aware of the seeming difficulties which have been built up upon what appears to the uninformed to be a solid foundation. I meet constantly with the argument that the doctrine of evolution cannot be well founded because it requires the lapse of a very vast period of time; while the duration of life upon the earth, thus implied, is inconsistent with the conclusions arrived at by the astronomer and the physicist. I may venture to say that I am familiar with those conclusions, inasmuch as some years ago, when president of the Geological Society of London, I took the liberty of criticising them, and of showing in what respects, as it appeared to me, they lacked complete and thorough demonstration. But, putting that point aside, suppose that, as the astronomers, or some of them, and some physical philosophers tell us, it is impossible that life could have endured upon the earth for so long a period as is required by the doctrine of evolution--supposing that to be proved--I desire to be informed, what is the foundation for the statement that evolution does require so great a time? The biologist knows nothing whatever of the amount of time which may be required for the process of evolution. It is a matter of fact that the equine forms, which I have described to you, occur, in the order stated, in the Tertiary formations. But I have not the slightest means of guessing whether it took a million of years, or ten millions, or a hundred millions, or a thousand millions of years, to give rise to that series of changes. A biologist has no means of arriving at any conclusions as to the amount of time which may be needed for a certain quantity of organic change. He takes his time from the geologist. The geologist, considering the rate at which deposits are formed and the rate at which denudation goes on upon the surface of the earth, arrives at more or less justifiable conclusions as to the time which is required for the deposit of a certain thickness of rocks; and if he tells me that the Tertiary formations required 500,000,000 years for their deposit, I suppose he has good ground for what he says, and I take that as a measure of the duration of the evolution of the horse from the _Orohippus_ up to its present condition. And, if he is right, undoubtedly evolution is a very slow process, and requires a great deal of time. But suppose now, that an astronomer or a physicist--for instance, my friend Sir William Thomson--tells me that my geological authority is quite wrong; and that he has weighty evidence to show that life could not possibly have existed upon the surface of the earth 500,000,000 years ago, because the earth would have then been too hot to allow of life, my reply is: "That is not my affair; settle that with the geologist, and when you have come to an agreement among yourselves I will adopt your conclusions." We take our time from the geologists and physicists, and it is monstrous that, having taken our time from the physical philosopher's clock, the physical philosopher should turn round upon us, and say we are too fast or too slow. What we desire to know is, is it a fact that evolution took place? As to the amount of time which evolution may have occupied, we are in the hands of the physicist and the astronomer, whose business it is to deal with those questions. [Illustration: Fig. 9] Fore Foot. Hind Foot. Fore-arm. Leg. Upper Molar. Lower Molar. RECENT. EQUUS. PLIOCENE. PLIOHIPPUS. PROTOHIPPUS (_Hipparion_). MIOCENE. MIOHIPPUS (_Anchitherium_). MESOHIPPUS. EOCENE. OROHIPPUS. FOOTNOTES: [5] I use the word "type" because it is highly probable that many of the forms of _Anchitherium_-like and _Hipparion_-like animals existed in the Miocene and Pliocene epochs, just as many species of the horse tribe exist now; and it is highly improbable that the particular species of _Anchitherium_ or _Hipparion_, which happen to have been discovered, should be precisely those which have formed part of the direct line of the horse's pedigree. [6] Since this lecture was delivered, Professor Marsh has discovered a new genus of equine mammals (_Eohippus_) from the lowest Eocene deposits of the West, which corresponds very nearly to this description.--_American Journal of Science_, November, 1876. FIGHTING PESTS WITH INSECT ALLIES LELAND O. HOWARD [Dr. Howard is Chief of the Division of Entomology in the United States Department of Agriculture at Washington. He is a lecturer at Swarthmore College and at Georgetown University. He has written "The Insect Book," published by Doubleday, Page & Co., New York; and a work on Mosquitoes, issued by McClure, Phillips & Co., New York. Both are books of interest from the hand of a master: they are fully illustrated. The narrative which follows appeared in _Everybody's Magazine_, June, 1901.] Some twenty-five years ago there appeared suddenly upon certain acacia trees at Menlo Park, California, a very destructive scale bug. It rapidly increased and spread from tree to tree, attacking apples, figs, pomegranates, quinces, and roses, and many other trees and plants, but seeming to prefer to all other food the beautiful orange and lemon trees which grow so luxuriantly on the Pacific Coast, and from which a large share of the income of so many fruit-growers is gained. This insect, which came to be known as the _white scale_ or _fluted scale_ or the _Icerya_ (from its scientific name), was an insignificant creature in itself, resembling a small bit of fluted wax a little more than a quarter of an inch long. But when the scales had once taken possession of a tree, they swarmed over it until the bark was hidden; they sucked its sap through their minute beaks until the plant became so feeble that the leaves and young fruit dropped off, a hideous black smut-fungus crept over the young twigs, and the weakened tree gradually died. In this way orchard after orchard of oranges, worth a thousand dollars or more an acre, was utterly destroyed; the best fruit-growing sections of the State were invaded, and ruin stared many a fruit-grower in the face. This spread of the pest was gradual, extending through a series of years, and not until 1886 did it become so serious a matter as to attract national attention. In this year an investigation was begun by the late Professor C. V. Riley, the Government entomologist then connected with the Department of Agriculture at Washington. He sent two agents to California, both of whom immediately began to study the problem of remedies. In 1887 he visited California himself, and during that year published an elaborate report giving the results of the work up to that point. The complete life-history of the insect had been worked out, and a number of washes had been discovered which could be applied to the trees in the form of a spray, and which would kill a large proportion of the pests at a comparatively small expense. But it was soon found that the average fruit-grower would not take the trouble to spray his trees, largely from the fact that he had experimented for some years with inferior washes and quack nostrums, and from lack of success had become disgusted with the whole idea of using liquid compounds. Something easier, something more radical was necessary in his disheartened condition. Meantime, after much sifting of evidence and much correspondence with naturalists in many parts of the world, Professor Riley had decided that the white scale was a native of Australia, and had been first brought over to California accidentally upon Australian plants. In the same way it was found to have reached South Africa and New Zealand, in both of which colonies it had greatly increased, and had become just such a pest as it is in California. In Australia, however, its native home, it did not seem to be abundant, and was not known as a pest--a somewhat surprising state of affairs, which put the entomologist on the track of the results which proved of such great value to California. He reasoned that, in his native home, with the same food plants upon which it flourished abroad in such great abundance, it would undoubtedly do the same damage that it does in South Africa, New Zealand, and California, if there were not in Australia some natural enemy, probable some insect parasite or predatory beetle, which killed it off. It became therefore important to send a trained man to Australia to investigate this promising line. After many difficulties in arranging preliminaries relating to the payment of expenses (in which finally the Department of State kindly assisted), one of Professor Riley's assistants, a young German named Albert Koebele, who had been with him for a number of years, sailed for Australia in August, 1888. Koebele was a skilled collector and an admirable man for the purpose. He at once found that Professor Riley's supposition was correct: there existed in Australia small flies which laid their eggs in the white scales, and these eggs hatched into grubs which devoured the pests. He also found a remarkable little ladybird, a small, reddish-brown convex beetle, which breeds with marvellous rapidity and which, with voracious appetite, and at the same time with discriminating taste, devours scale after scale, but eats fluted scales only--does not attack other insects. This beneficial creature, now known as the Australian ladybird, or the Vedalia, Mr. Koebele at once began to collect in large numbers, together with several other insects found doing the same work. He packed many hundreds of living specimens of the ladybird, with plenty of food, in tin boxes, and had them placed on ice in the ice-box of the steamer at Sydney; they were carried carefully to California, where they were liberated upon orange trees at Los Angeles. [Illustration: Vedalia, or Australian Ladybird] These sendings were repeated for several months, and Mr. Koebele, on his return in April, 1889, brought with him many more living specimens which he had collected on his way home in New Zealand, where the same Vedalia had been accidentally introduced a year or so before. [Illustration: Larvæ of Vedalia eating White Scale] The result more than justified the most sanguine expectations. The ladybirds reached Los Angeles alive, and, with appetites sharpened by their long ocean voyage, immediately fell upon the devoted scales and devoured them one after another almost without rest. Their hunger temporarily satisfied, they began to lay eggs. These eggs hatched in a few days into active grub-like creatures--the larvæ of the beetles--and these grubs proved as voracious as their parents. They devoured the scales right and left, and in less than a month transformed once more to beetles. And so the work of extermination went on. Each female beetle laid on an average 300 eggs, and each of these eggs hatched into a hungry larva. Supposing that one-half of these larvæ produced female beetles, a simple calculation will show that in six months a single ladybird became the ancestor of 75,000,000,000 of other ladybirds, each capable of destroying very many scale insects. [Illustration: Twig of olive infected with Black Scale] Is it any wonder, then, that the fluted scales soon began to disappear? Is it any wonder that orchard after orchard was entirely freed from the pest, until now over a large section of the State hardly an Icerya is to be found? And could a more striking illustration of the value of the study of insects possibly be instanced? In less than a year from the time when the first of these hungry Australians was liberated from his box in Los Angeles the orange trees were once more in bloom and were resuming their old-time verdure--the Icerya had become practically a thing of the past. [Illustration: Rhizobius, the imported enemy of the Black Scale of the Olive.] This wonderful success encouraged other efforts in the same direction. The State of California some years later sent the same entomologist, Koebele, to Australia to search for some insect enemy of the black scale, an insect which threatened the destruction of the extensive olive orchards of California. He found and successfully introduced another ladybird beetle, known as _Rhizobius ventralis_, a little dark-coloured creature which has thrived in the California climate, especially near the seacoast, and in the damp air of those regions has successfully held the black scale in check. It was found, however, that back from the seacoast this insect did not seem to thrive with the same vigor, and the black scale held its own. Then a spirited controversy sprung up among the olive-growers, those near the seacoast contending that the _Rhizobius_ was a perfect remedy for the scale, while those inland insisted that it was worthless. A few years later it was discovered that this olive enemy in South Europe is killed by a little caterpillar, which burrows through scale after scale eating out their contents, and an effort was made to introduce the caterpillar into California, but these efforts failed. Within the past two years it has been found that a small parasitic fly exists in South Africa which lays its eggs in the same black scale, and its grub-like larvæ eat out the bodies of the scales and destroy them. The climate of the region in which this parasite exists is dry through a large part of the year, and therefore this little parasitic fly, known as _Scutellista_, was thought to be the needed insect for the dry California regions. With the help of Mr. C. P. Lounsbury, the Government entomologist of Cape Colony, living specimens of this fly were brought to this country, and were colonized in the Santa Clara Valley, near San José, California, where they have perpetuated themselves and destroyed many of the black scales, and promise to be most successful in their warfare against the injurious insect. This same _Scutellista_ parasite had, curiously enough, been previously introduced in an accidental manner into Italy, probably from India, and probably in scale-insects living on ornamental plants brought from India. But in Italy it lives commonly in another scale insect, and with the assistance of the learned Italian, Professor Antonio Berlese, the writer made an unsuccessful attempt to introduce and establish it a year earlier in some of our Southern States, where it was hoped it would destroy certain injurious insects known as "wax scales." In the meantime the United States, not content with keeping all the good things to herself, has spread the first ladybird imported--the _Vedalia_--to other countries. Four years ago the white scale was present in enormous numbers in orange groves on the left bank of the river Tagus, in Portugal, and threatened to wipe out the orange-growing industry in that country. The California people, in pursuance of a far-sighted policy, had with great difficulty, owing to lack of food, kept alive some colonies of the beneficial beetle, and specimens were sent to Portugal which reached there alive and flourishing. They were tended for a short time, and then liberated in the orange groves, with precisely the same result as in California. In a few months the scale insects were almost entirely destroyed, and the Portuguese orange-growers saved from enormous loss. This good result in Portugal was not accomplished without opposition. It was tried experimentally at the advice of the writer, and in the face of great incredulity on the part of certain Portuguese newspapers and of some officials. By many prominent persons the account published of the work of the insect in the United States was considered as untrustworthy, and simply another instance of American boasting. But the opposition was overruled, and the triumphant result silenced all opposition. It is safe to say that the general opinion among Portuguese orange-growers to-day is very favourable to American enterprise and practical scientific acumen. The _Vedalia_ was earlier sent to the people in Alexandria and Cairo, Egypt, where a similar scale was damaging the fig trees and other valuable plants, and the result was again the same, the injurious insects were destroyed. This was achieved only after extensive correspondence and several failures. The active agent in Alexandria was Rear Admiral Blomfield, of the British Royal Navy, a man apparently of wide information, good judgment, and great energy. The same thing occurred when the California people sent this saviour of horticulture to South Africa, where the white scale had also made its appearance. It is not only beneficial insects, however, which are being imported, but diseases of injurious insects. In South Africa the colonists suffer severely from swarms of migratory grasshoppers, which fly from the north and destroy their crops. They have discovered out there a fungus disease, which under favorable conditions kills off the grasshoppers in enormous numbers. At the Bacteriological Institute in Grahamstown, Natal, they have cultivated this fungus in culture tubes, and have carried it successfully throughout the whole year; and they have used it practically by distributing these culture tubes wherever swarms of grasshoppers settle and lay their eggs. The disease, once started in an army of young grasshoppers, soon reduces them to harmless numbers. The United States Government last year secured culture tubes of this disease, and experiments carried on in Colorado and in Mississippi show that the vitality of the fungus had not been destroyed by its long ocean voyage, and many grasshoppers were killed by its spread. During the past winter other cultures were brought over from Cape Colony, and the fungus is being propagated in the Department of Agriculture for distribution during the coming summer in parts of the country where grasshoppers may prove to be destructively abundant. [Illustration: Grasshopper dying from Fungus Disease] Although we practically no longer have those tremendous swarms of migratory grasshoppers which used to come down like devastating armies in certain of our Western States and in a night devour everything green, still, almost every year, and especially in the West and South, there is somewhere a multiplication of grasshoppers to a very injurious degree, and it is hoped that the introduced fungus can be used in such cases. Persons officially engaged in searching for remedies for injurious insects all over the world have banded themselves together in a society known as the Association of Economic Entomologists. They are constantly interchanging ideas regarding the destruction of insects, and at present active movements are on foot in this direction of interchanging beneficial insects. Entomologists in Europe will try the coming summer to send to the United States living specimens of a tree-inhabiting beetle which eats the caterpillar of the gipsy moth, and which will undoubtedly also eat the caterpillar so common upon the shade-trees of our principal Eastern cities, which is known as the Tussock moth caterpillar. An entomologist from the United States, Mr. C. L. Marlatt, has started for Japan, China, and Java, for the purpose of trying to find the original home of the famous San José scale--an insect which has been doing enormous damage in the apple, pear, peach, and plum orchards of the United States--and if he finds the original home of this scale, it is hoped that some natural enemy or parasite will be discovered which can be introduced into the United States to the advantage of our fruit-growers. Professor Berlese of Italy, and Dr. Reh, of Germany, will attempt the introduction into Europe of some of the parasites of injurious insects which occur in the United States, and particularly those of the woolly root-louse of the apple, known in Europe as the "American blight"--one of the few injurious insects which probably went to Europe from this country, and which in the United States is not so injurious as it is in Europe. It is a curious fact, by the way, that while we have had most of our very injurious insects from Europe, American insects, when accidentally introduced into Europe, do not seem to thrive. The insect just mentioned, and the famous grape-vine _Phylloxera_, a creature which caused France a greater economic loss than the enormous indemnity which she had to pay to Germany after the Franco-Prussian War, are practically the only American insects with which we have been able to repay Europe for the insects which she has sent us. Climatic differences, no doubt, account for this strange fact, and our longer and warmer summers are the principal factor. It is not alone the parasitic and predaceous insects which are beneficial. A new industry has been brought into the United States during the past two years by the introduction and acclimatization of the little insect which fertilizes the Smyrna fig in Mediterranean countries. The dried-fig industry in this country has never amounted to anything. The Smyrna fig has controlled the dried-fig markets of the world, but in California the Smyrna fig has never held its fruit, the young figs dropping from the trees without ripening. It was found that in Mediterranean regions a little insect, known as the _Blastophaga_, fertilizes the flowers of the Smyrna fig with pollen from the wild fig which it inhabits. The United States Department of Agriculture in the spring of 1899 imported successfully some of these insects through one of its travelling agents, Mr. W. T. Swingle, and the insect was successfully established at Fresno in the San Joaquin Valley. A far-sighted fruit-grower, Mr. George C. Roeding, of Fresno, had planted some years previously an orchard of 5,000 Smyrna fig trees and wild fig trees, and his place was the one chosen for the successful experiment. The little insect multiplied with astonishing rapidity, was carried successfully through the winter of 1899-1900, and in the summer of 1900 was present in such great numbers that it fertilized thousands of figs, and fifteen tons of them ripened. When these figs were dried and packed it was discovered that they were superior to the best imported figs. They contained more sugar and were of a finer flavor than those brought from Smyrna and Algeria. The _Blastophaga_ has come to stay, and the prospects for a new and important industry are assured. With all these experiments the criticism is constantly made that unwittingly new and serious enemies to agriculture may be introduced. The unfortunate introduction of the English sparrow into this country is mentioned, and the equally unfortunate introduction of the East Indian mongoose into the West Indies as well. The fear is expressed that the beneficial parasitic insects, after they have destroyed the injurious insects, will either themselves attack valuable crops or do something else of an equally harmful nature. But there is no reason for such alarm. The English sparrow feeds on all sorts of things, and the East Indian mongoose, while it was introduced into Jamaica to kill snakes, was found, too late, to be also a very general feeder. As a matter of fact, after the snakes were destroyed, and even before, it attacked young pigs, kids, lambs, calves, puppies, and kittens, and also destroyed bananas, pineapples, corn, sweet potatoes, cocoanuts, peas, sugar corn, meat, and salt provisions and fish. But with the parasitic and predatory insects the food habits are definite and fixed. They can live on nothing but their natural food, and in its absence they die. The Australian ladybird originally imported, for example, will feed upon nothing but scale insects of a particular genus, and, as a matter of fact, as soon as the fluted scales became scarce the California officials had the greatest difficulty in keeping the little beetles alive, and were actually obliged to cultivate for food the very insects which they were formerly so anxious to wipe out of existence! With the _Scutellista_ parasite the same fact holds. The fly itself does not feed, and its young feed only upon certain scale insects, and so with all the rest. All of these experiments are being carried on by men learned in the ways of insects, and only beneficial results, or at the very least negative ones, can follow. And even where only one such experiment out of a hundred is successful, what a saving it will mean! We do not expect the time to come when the farmer, finding Hessian fly in his wheat, will have only to telegraph the nearest experiment station, "Send at once two dozen first-class parasites;" but in many cases, and with a number of different kinds of injurious insects, especially those introduced from foreign countries, it is probable that we can gain much relief by the introduction of their natural enemies from their original home. THE STRANGE STORY OF THE FLOWERS GEORGE ILES [From "The Wild Flowers of America," copyright by G. H. Buek & Co., New York, 1894, by their kind permission. The American edition is out of print: the Canadian edition, "Wild Flowers of Canada," is published by Graham & Co., Montreal, Canada. The work describes and illustrates in their natural tints nearly three hundred beautiful flowers.] Imagine a Venetian doge, a French crusader, a courtier of the time of the second Charles, an Ojibway chief, a Justice of the Supreme Court, in the formal black of evening dress, and how much each of them would lose! Where there is beauty, strength or dignity, dress can heighten it; where all these are lacking, their absence is kept out of mind by raiment in itself worthy to be admired. If dress artificial has told for much in the history of human-kind, dress natural has told for yet more in the lesser world of plant and insect life. In some degree the tiny folk that reign in the air, like ourselves, are drawn by grace of form, by charm of colour; of elaborate display of their attractions moths, butterflies and beetles are just as fond as any belles of the ball-room. Now let us bear in mind that of all the creatures that share the earth with man, the one that stands next to him in intelligence is neither a biped nor a quadruped, but that king of the insect tribe, the ant, which can be a herdsman and warehouse-keeper, an engineer and builder, an explorer and a general. With all his varied powers the ant lacks a peculiarity in his costume which has denied him enlistment in a task of revolution in which creatures far his inferiors have been able to change the face of the earth. And the marvel of this peculiarity of garb which has meant so much, is that it consists in no detail of graceful outline, or beauty of tint, but solely in the minor matter of texture. The ant, warrior that he is, wears smooth and shining armour; the bee, the moth and the butterfly are clad in downy vesture, and simply because thus enabled to catch dust on their clothes these insects, as weavers of the web of life, have counted for immensely more than the ant with all his brains and character. To understand the mighty train of consequences set in motion by this mere shagginess of coat, let us remember that, like a human babe, every flowering plant has two parents. These two parents, though a county's breadth divide them, are wedded the instant that pollen from the anther of one of them meets the stigma of the other. Many flowers find their mates upon their own stem; but, as in the races of animals, too close intermarriage is hurtful, and union with a distant stock promotes both health and vigor. Hence the great gain which has come to plants by engaging the wind as their matchmaker--as every summer shows us in its pollen-laden air, the oaks, the pines, the cottonwoods, and a host of other plants commit to the breeze the winged atoms charged with the continuance of their kind. Nevertheless, long as the wind has been employed at this work, it has not yet learned to do it well; nearly all the pollen entrusted to it is wasted, and this while its production draws severely upon the strength of a plant. As good fortune will have it, a great many flowers close to their pollen yield an ample supply of nectar: a food esteemed delicious by the whole round of insects, winged and wingless. While ants might sip this nectar of ages without plants being any the better or the worse; a very different result has followed upon the visits of bees, wasps, and other hairy-coated callers. These, as they devour nectar, dust themselves with the pollen near by. Yellowed or whitened with this freightage, moth and butterfly, as they sail through the air, know not that they are publishing the banns of marriage between two blossoms acres or, it may be, miles apart. Yet so it is. Alighting on a new flower the insect rubs a pollen grain on a stigma ready to receive it, and lo! the rites of matrimony are solemnized then and there. Unwittingly the little visitor has wrought a task bigger with fate than many an act loudly trumpeted among the mightiest deeds of men! On the threshold of a Lady's Slipper a bee may often be detected in the act of entrance. In the Sage-flower he finds an anther of the stamen which, pivoted on its spring, dusts him even more effectually. [Illustration: Sage-flower and Bee] Bountifully to spread a table is much, but not enough, for without invitation how can hospitality be dispensed? To the feast of nectar the blossoms join their bidding; and those most conspicuously borne and massed, gayest of hue, richest in odor, secure most guests, and are therefore most likely to transmit to their kind their own excellences as hosts and entertainers. Thus all the glories of the blossoms have arisen in doing useful work; their beauty is not mere ornament, but the sign and token of duty well performed. Our opportunity to admire the radiancy and perfume of a jessamine or a pond-lily is due to the previous admiration of uncounted winged attendants. If a winsome maid adorns herself with a wreath from the garden, and carries a posy gathered at the brookside, it is for the second time that their charms are impressed into service; for the flowers' own ends of attraction all their scent and loveliness were called into being long before. Let us put flowers of the blue flag beside those of the maple, and we shall have a fair contrast between the brilliancy of blossoms whose marrier has been an insect, and the dinginess of flowers indebted to the services of the wind. Can it be that both kinds of flowers are descended from forms resembling each other in want of grace and colour? Such, indeed, is the truth. But how, as the generations of the flowers succeeded one another, did differences so striking come about? In our rambles afield let us seek a clue to the mystery. It is late in springtime, and near the border of a bit of swamp we notice a clump of violets: they are pale of hue, and every stalk of them rises to an almost weedy height. [Illustration: Wild Rose, Single] Twenty paces away, on a knoll of dry ground, we find more violets, but these are in much deeper tints of azure and yellow, while their stalks are scarcely more than half as tall as their brethren near the swamp. Six weeks pass by. This time we walk to a wood-lot close to a brimming pond. At its edge are more than a score wild-rose bushes. On the very first of them we see that some of the blossoms are a light pink, others a pink so deep as to seem dashed with vivid red. And while a flower here and there is decidedly larger and more vigorous than its fellows, a few of the blossoms are undersized and puny: the tide of life flows high and merrily in a fortunate rose or two, it seems to ebb and falter by the time it reaches one or two of their unhappy mates. As we search bush after bush we are at last repaid for sundry scratches from their thorns by securing a double rose, a "sport," as the gardener would call it. And in the broad meadow between us and home we well know that for the quest we can have not only four-leaved clovers, but perchance a handful of five and six-leaved prizes. The secret is out. Flowers and leaves are not cast like bullets in rigid moulds, but differ from their parents much as children do. Usually the difference is slight, at times it is as marked as in our double rose. Whenever the change in a flower is for the worse, as in the sickly violets and roses we have observed, that particular change ends there--with death. But when the change makes a healthy flower a little more attractive to its insect ministers, it will naturally be chosen by them for service, and these choosings, kept up year after year, and century upon century, have at last accomplished much the same result as if the moth, the bee, and the rest of them had been given power to create blossoms of the most welcome forms, the most alluring tints, the most bewitching perfumes. In farther jaunts afield we shall discover yet more. It is May, and a heavy rainstorm has caused the petals of a trillium to forget themselves and return to their primitive hue of leafy green. A month later we come upon a buttercup, one of whose sepals has grown out as a small but perfect leaf. Later still in summer we find a rose in the same surprising case, while not far off is a columbine bearing pollen on its spurs instead of its anthers. What family tie is betrayed in all this? No other than that sepals, petals, anthers and pistils are but leaves in disguise, and that we have detected nature returning to the form from which ages ago she began to transmute the parts of flowers in all their teeming diversity. The leaf is the parent not only of all these but of delicate tendrils, which save a vine the cost of building a stem stout enough to lift it to open air and sunshine. However thoroughly, or however long, a habit may be impressed upon a part of a plant, it may on occasion relapse into a habit older still, resume a shape all but forgotten, and thus tell a story of its past that otherwise might remain forever unsuspected. Thus it is with the somewhat rare "sport" that gives us a morning glory or a harebell in its primitive form of unjoined petals. The bell form of these and similar flowers has established itself by being much more effective than the original shape in dusting insect servitors with pollen. Not only the forms of flowers but their massing has been determined by insect preferences; a wide profusion of blossoms grow in spikes, umbels, racemes and other clusters, all economizing the time of winged allies, and attracting their attention from afar as scattered blossoms would fail to do. Besides this massing, we have union more intimate still as in the dandelion, the sun-flower and the marigold. These and their fellow composites each seem an individual; a penknife discloses each of them to be an aggregate of blossoms. So gainful has this kind of co-operation proved that composites are now dominant among plants in every quarter of the globe. As to how composites grew before they learned that union is strength, a hint is dropped in the "sport" of the daisy known as "the hen and chickens," where perhaps as many as a dozen florets, each on a stalk of its own, ray out from a mother flower. While for the most part insects have been mere choosers from among various styles of architecture set before them by plants, they have sometimes risen to the dignity of builders on their own account, and without ever knowing it. The buttress of the larkspur has sprung forth in response to the pressure of one bee's weight after another, and many a like structure has had the very same origin,--or shall we say, provocation? In these and in other examples unnumbered, culminating in the marvellous orchids and their ministers, there has come about the closest adaptation of flower-shape to insect-form, the one now clearly the counterpart of the other. We must not forget that the hospitality of a flower is after all the hospitality of an inn-keeper who earns and requires payment. Vexed as flowers are apt to be by intruders that consume their stores without requital, no wonder that they present so ample an array of repulsion and defence. Best of all is such a resource as that of the red clover, which hides its honey at the bottom of a tube so deep that only a friendly bumblebee can sip it. Less effective, but well worth a moment's examination, are the methods by which leaves are opposed as fences for the discouragement of thieves. Here, in a Bellwort, is a perfoliate leaf that encircles the stem upon which it grows; and there in a Honeysuckle is a connate leaf on much the same plan, formed of two leaves, stiff and strong, soldered at their bases. Sometimes the pillager meets prickles that sting him, as in the roses and briers; and if he is a little fellow he is sure to regard him with intense disgust, a bristly guard of wiry hair--hence the commonness of that kind of fortification. Against enemies of larger growth a tree or shrub will often aim sharp thorns--another piece of masquerade, for thorns are but branches checked in growth, and frowning with a barb in token of disappointment at not being able to smile in a blossom. In every jot and tittle of barb and prickle, of the glossiness which disheartens or the gumminess which ensnares, we may be sure that equally with all the lures of hue, form and scent, nothing, however trifling it may seem, is as we find it, except through usefulness long tested and approved. In flowers, much that at first glance looks like idle decoration, on closer scrutiny reveals itself as service in disguise. In penetrating these disguises and many more of other phases, the student of flowers delights to busy himself. He loves, too, to detect the cousinship of plants through all the change of dress and habit due to their rearing under widely different skies and nurture, to their being surrounded by strangely contrasted foes and friends. Often he can link two plants together only by going into partnership with a student of the rocks, by turning back the records of the earth until he comes upon a flower long extinct, a plant which ages ago found the struggle for life too severe for it. He ever takes care to observe his flowers accurately and fully, but chiefly that he may rise from observation to explanation, from bare facts to their causes, from declaring What, to understanding, Whence and How. One of the stock resources of novelists, now somewhat out of date, was the inn-keeper who beamed in welcome of his guest, grasped his hand in gladness, and loaded a table for him in tempting array, and all with intent that later in the day (or night) he might the more securely plunge a dagger into his victim's heart--if, indeed, he had not already improved an opportunity to offer to that victim's lips a poisoned cup. This imagined treachery might well have been suggested by the behaviour of certain alluring plants that so far from repelling thieves, or discouraging pillagers, open their arms to all comers--with purpose of the deadliest. Of these betrayers the chief is the round-leaved sun-dew, which plies its nefarious vocation all the way from Labrador to Florida. Its favourite site is a peat-bog or a bit of swampy lowland, where in July and August we can see its pretty little white blossoms beckoning to wayfaring flies and moths their token of good cheer! Circling the flower-stalk, in rosette fashion, are a dozen or more round leaves, each of them wearing scores of glands, very like little pins, a drop of gum glistening on each and every pin by way of head. This appetizing gum is no other than a fatal stick-fast, the raying pins closing in its aid the more certainly to secure a hapless prisoner. Soon his prison-house becomes a stomach for his absorption. Its duty of digestion done, the leaf in all seeming guilessness once more expands itself for the enticement of a dupe. To see how much the sun-dew must depend upon its meal of insects we have only to pull it up from the ground. A touch suffices--it has just root enough to drink by; the soil in which it makes, and perhaps has been obliged to make, its home has nothing else but drink to give it. Less accomplished in its task of assassination is the common butterwort to be found on wet rocks in scattered districts of Canada and the States adjoining Canada. Surrounding its pretty violet flowers, of funnel shape, are gummy leaves which close upon their all too trusting guests, but with less expertness than the sun-dew's. The butterwort is but a 'prentice hand in the art of murder, and its intended victims often manage to get away from it. Built on a very different model is the bladderwort, busy in stagnant ponds near the sea coast from Nova Scotia to Texas. Its little white spongy bladders, about a tenth of an inch across, encircle the flowering stem by scores. From each bladder a bunch of twelve or fifteen hairy prongs protrude, giving the structure no slight resemblance to an insect form. These prongs hide a valve which, as many an unhappy little swimmer can attest, opens inward easily enough, but opens outward never. As in the case of its cousinry a-land, the bladderwort at its leisure dines upon its prey. [Illustration: Venus' Fly Trap--Open with a Welcome] In marshy places near the mouth of the Cape Fear River, in the vicinity of Wilmington, North Carolina, grows the Venus' fly-trap, most wonderful of all the death-dealers of vegetation. Like much else in nature's handiwork this plant might well have given inventors a hint worth taking. The hairy fringes of its leaves are as responsive to a touch from moth or fly as the sensitive plant itself. And he must be either a very small or a particularly sturdy little captive that can escape through the sharp opposed teeth of its formidable snare. It is one of the unexplained puzzles of plant life that the Venus' fly-trap, so marvellous in its ingenuity, should not only be confined to a single district, but should seem to be losing its hold of even that small kingdom. Of still another type is the pitcher plant, or side-saddle flower, which flaunts its deep purple petals in June in many a peat-bog from Canada southward to Louisiana and Florida. Its leaves develop themselves into lidded cups, half-filled with sweetish juice, which first lures a fly or ant, then makes him tipsy, and then despatches him. The broth resulting is both meat and drink to the plant, serving as a store and reservoir against times of drought and scarcity. [Illustration: Shut for Slaughter] Now the question is, How came about this strange and somewhat horrid means of livelihood? How did plants of so diverse families turn the tables on the insect world, and learn to eat instead of being themselves devoured? A beginner in the builder's art finds it much more gainful to examine the masonry of foundations, the rearing of walls, the placing of girders and joists, the springing of arches and buttresses, than to look at a cathedral, a courthouse, or a bank, finished and in service. In like manner a student of insect-eating plants tries to find their leaves in the making, in all the various stages which bridge their common forms with the shapes they assume when fully armed and busy. Availing himself of the relapses into old habits which plants occasionally exhibit under cultivation, Mr. Dickson has taught us much regarding the way the pitcher plant of Australia, the _Cephalotus_, has come to be what it is. He has arranged in a connected series all the forms of its leaf from that of a normal leaf with a mere dimple in it, to the deeply pouched and lidded pitcher ready for deceitful hospitalities. And similar transformations have without doubt taken place in the pitcher plants of America. Observers in the Cape of Good Hope have noted two plants _Roridula dentata_ and _Biblys gigantea_, which are evidently following in the footsteps of the sundews, and may be expected in the fulness of years to be their equal partners in crime. But why need we wander so far as South Africa to find the germs of this strange rapacity when we can see at home a full dozen species of catch-fly, sedums, primulas, and geraniums pouring out glutinous juices in which insects are entangled? Let stress of hunger, long continued, force any of these to turn its attention to the dietary thus proffered, and how soon might not the plant find in felony the sustenance refused to honest toil? But after all the plants that have meat for dinner are only a few. The greater part of the vegetable kingdom draws its supplies from the air and the soil. Those plants, and they are many, that derive their chief nourishment from the atmosphere have a decidedly thin diet. Which of us would thrive on milk at the rate of a pint to five hogsheads of water? Such is the proportion in which air contains carbonic acid gas, the main source of strength for many thousands of trees, shrubs, and other plants. No wonder that they array themselves in so broad an expanse of leafage. An elm with a spread of seventy feet is swaying in the summer breeze at least five acres of foliage as its lungs and stomach. Beyond the shade of elms and maples let us stroll past yonder stretch of pasture and we shall notice how the grass in patches here and there deepens into green of the richest--a plain token of moisture in the hollows--a blessing indeed in this dry weather. In the far West and Northwest the buffalo grass has often to contend with drought for months together, so that it has learned to strike deep in quest of water to quench its thirst. It is a by-word among the ranchmen that the roots go clear through the earth and are clinched as they sprout from the ground in China. Joking apart, they have been found sixty-eight feet below the surface of the prairie, and often in especially dry seasons cattle would perish were not these faithful little well-diggers and pumpers constantly at work for them. In the river valleys of Arizona although the air is dry the subsoil water is near the surface of the ground. Here flourishes the mesquit tree, _Prosopis juliflora_, with a tale to tell well worth knowing. When a mesquit seems stunted, it is because its strength is withdrawn for the task of delving to find water; where a tree grows tall with goodly branches, it betokens success in reaching moisture close at hand. Thus in shrewdly reading the landscape a prospector can choose the spot where with least trouble he can sink his well. And plants discover provender in the soil as well as drink. Nearer home than Arizona we have only to dislodge a beach pea from the ground to see how far in search of food its roots have dug amid barren stones and pebbles. Often one finds a plant hardly a foot high with roots extending eight feet from its stem. And beyond the beaches where the beach peas dig so diligently are the seaweeds--with a talent for picking and choosing all their own. Dr. Julius Sachs, a leading German botanist, believes that the parts of plants owe their form, as crystals do, to their peculiarities of substance; that just as salt crystallizes in one shape and sugar in another, so a seaweed or a tulip is moulded by the character of its juices. Something certainly of the crystal's faculty for picking out particles akin to itself, and building with them, is shown by the kelp which attracts from the ocean both iodine and bromine--often dissolved though they are in a million times their bulk of sea water. This trait of choosing this or that dish from the feast afforded by sea or soil or air is not peculiar to the seaweeds; every plant displays it. Beech trees love to grow on limestone and thus declare to the explorer the limestone ridge he seeks. In the Horn silver mine, of Utah, the zinc mingled with the silver ore is betrayed by the abundance of the zinc violet, a delicate and beautiful cousin of the pansy. In Germany this little flower is admittedly a signal of zinc in the earth, and zinc is found in its juices. The late Mr. William Dorn, of South Carolina, had faith in a bush, of unrecorded name, as betokening gold-bearing veins beneath it. That his faith was not without foundation is proved by the large fortune he won as a gold miner in the Blue Ridge country--his guide the bush aforesaid. Mr. Rossiter W. Raymond, the eminent mining engineer of New York, has given some attention to this matter of "indicative plants." He is of the opinion that its unwritten lore among practical miners, prospectors, hunters, and Indians is well worth sifting. Their observations, often faulty, may occasionally be sound and valuable enough richly to repay the trouble of separating truth from error. When we see how important as signs of water many plants can be, why may we not find other plants denoting the minerals which they especially relish as food or condiment? Of more account than gold or silver are the harvests of wheat and corn that ripen in our fields. There the special appetites of plants have much more than merely curious interest for the farmer. He knows full well that his land is but a larder which serves him best when not part but all its stores are in demand. Hence his crop "rotation," his succession of wheat to clover, of grass to both. Were he to grow barley every year he would soon find his soil bared of all the food that barley asks, while fare for peas or clover stood scarcely broached. If he insists on planting barley always, then he must perforce restore to the land the food for barley constantly withdrawn. [Illustration: Maple Seed, with pair of wings] A plant may diligently find food and drink, pour forth delicious nectar, array itself with flowers as gayly as it can, and still behold its work unfinished. Its seed may be produced in plenty, and although as far as that goes it is well, it is not enough. Of what avail is all this seed if it falls as it ripens upon soil already overcrowded with its kind? Hence the vigorous emigration policy to be observed in plants of every name. Hence the fluffy sails set to catch the passing breeze by the dandelion, the thistle and by many more, including the southern plant of snowy wealth whose wings are cotton. With the same intent of seeking new fields are the hooks of the burdock, the unicorn plant, and the bur-parsley which impress as carriers the sheep and cattle upon a thousand hills. The Touch-me-not and the herb Robert adopt a different plan, and convert their seed-cases into pistols for the firing of seeds at as wide range as twenty feet or more. The maple, the ash, the hornbeam, the elm and the birch have yet another method of escape from the home acre. Their seeds are winged, and torn off in a gale are frequently borne two hundred yards away. And stronger wings than these are plied in the cherry tree's service. The birds bide the time when a blush upon the fruit betrays its ripeness. Then the cherries are greedily devoured, and their seed, preserved from digestion in their stony cases are borne over hill, dale, and river to some islet or brookside where a sprouting cherry plant will be free from the stifling rivalries suffered by its parent. Yoked in harness with sheep, ox, and bird as planter is yonder nimble squirrel. We need not begrudge him the store of nuts he hides. He will forget some of them, he will be prevented by fright or frost from nibbling yet more, and so without intending it he will ensure for others and himself a sure succession of acorns and butternuts. Very singular are the seeds that have come to resemble beetles; among these may be mentioned the seeds of the castor-oil plant and of the _Iatropha_. The pod of the _Biserrula_ looks like a worm, and a worm half-coiled might well have served as a model for the mimicry of the _Scorpiurus vermiculata_. All these are much more likely to enlist the services of birds than if their resemblances to insects were less striking. Nature elsewhere rich in hints to the gardener and the farmer is not silent here. A lesson plainly taught in all this apparatus for the dispersal of seeds is that the more various the planting the fuller the harvest. Now that from the wheat fields comes a cry of disappearing gains, it is time to heed the story told in the unbroken prairie that diversity in sowing means wealth in reaping. In a field of growing flax we can find--somewhat oftener than the farmer likes--a curious tribe of plants, the dodders. Their stems are thin and wiry, and their small white flowers, globular in shape, make the azure blossoms of the flax all the lovelier by contrast. As their cousins the morning glories are to this day, the dodders in their first estate were true climbers. Even now they begin life in an honest kind of way with roots of their own that go forth as roots should, seeking food where it is to be found in the soil. But if we pull up one of these little club-shaped roots we shall see that it has gone to work feebly and doubtfully; it seems to have a skulking expectation of dinner without having to dig and delve for it in the rough dirty ground. Nor is this expectation unfounded. Watch the stem of a sister dodder as it rises from the earth day by day, and it will be observed to clasp a stalk of flax very tightly; so tightly that its suckers will absorb the juices of its unhappy host. When, so very easily, it can regale itself with food ready to hand why should it take the trouble to drudge for a living? Like many another pauper demoralized by being fed in idleness, the plant now abandons honest toil, its roots from lack of exercise wither away, and for good and all it ceases to claim any independence whatever. Indeed, so deep is the dodder's degradation that if it cannot find a stem of flax, or hop, or other plant whereon to climb and thrive, it will simply shrivel and die rather than resume habits of industry so long renounced as to be at last forgotten. Like the lowly dodder the mistletoe is a climber that has discovered large opportunities of theft in ascending the stem of a supporting plant. On this continent the mistletoe scales a wide variety of trees and shrubs, preferring poplars and apple trees, where these are to be had. Its extremely slender stem, its meagre leaves, its small flowers, greenish and leathery, are all eloquent as to the loss of strength and beauty inevitable to a parasite. Rising as this singular plant does out of the branches of another with a distinct life all its own, it is no other than a natural graft, and it is very probable that from the hint it so unmistakably gives the first gardeners were not slow to adopt grafts artificial--among the resources which have most enriched and diversified both flowers and fruits. The dodders and mistletoes rob juices from the stem and branches of their unfortunate hosts; more numerous still are the unbidden guests that fasten themselves upon the roots of their prey. The broom-rape, a comparatively recent immigrant from Europe, lays hold of the roots of thyme in preference to other place of entertainment; the Yellow Rattle, the Lousewort, and many more attach themselves to the roots of grasses--frequently with a serious curtailment of crop. Yet in this very department of hers Nature has for ages hidden away what has been disclosed within twenty years as one of her least suspected marvels. It is no other than that certain parasites of field and meadow so far from being hurtful, are well worth cultivating for the good they do. For a long time the men who devoted themselves to the study of peas, beans, clovers, and other plants of the pulse family, were confronted with a riddle they could not solve. These plants all manage to enrich themselves with compounds of nitrogen, which make them particularly valuable as food, and these compounds often exist in a degree far exceeding the rate at which their nitrogen comes out of the soil. And this while they have no direct means of seizing upon the nitrogen contained in its great reservoir--the atmosphere. Upon certain roots of beans and peas it was noted that there were little round excrescences about the size of a small pin's head. These excrescences on examination with a microscope proved to be swarming with bacteria of minute dimensions. Further investigation abundantly showed that these little guests paid a handsome price for their board and lodging--while they subsisted in part on the juices of their host they passed into the bean or pea certain valuable compounds of nitrogen which they built from common air. At the Columbian Exposition, of 1893, one of the striking exhibits in the Agricultural Building set this forth in detail. Vials were shown containing these tiny subterranean aids to the farmer, and large photographs showed in natural size the vast increase of crop due to the farmer's taking bacteria into partnership. To-day these little organisms are cultivated of set purpose, and quest is being made for similar bacteria suitable to be harnessed in producing wheat, corn, and other harvests. These are times when men of science are discontented with mere observation. They wish to pass from watching things as nature presents them to putting them into relations wholly new. In 1866 DeBary, a close observer of lichens, felt confident that a lichen was not the simple growth it seems, but a combination of fungus and algæ. This opinion, so much opposed to honoured tradition, was scouted, but not for long. Before many months had passed Stahl took known algæ, and upon them sowed a known fungus, the result was a known lichen! The fungus turns out to be no other than a slave-driver that captures algæ in colonies and makes them work for him. He is, however, a slave-driver of an intelligent sort; his captives thrive under his mastery, and increase more rapidly for the healthy exercise he insists that they shall take. It is an afternoon in August and the sultry air compels us to take shelter in a grove of swaying maples. Beneath their shade every square yard of ground bears a score of infant trees, very few of them as much as a foot in stature. How vain their expectation of one day enjoying an ample spread of branch and root, of rising to the free sunshine of upper air! The scene, with its quivering rounds of sunlight, seems peace itself, but the seeming is only a mask for war as unrelenting as that of weaponed armies. For every ray of the sunbeam, for every atom of food, for every inch of standing room, there is deadly rivalry. To begin the fight is vastly easier than to maintain it, and not one in a hundred of these bantlings will ever know maturity. We have only to do what Darwin did--count the plants that throng a foot of sod in spring, count them again in summer, and at the summer's end, to find how great the inexorable carnage in this unseen combat, how few its survivors. So hard here is the fight for a foothold, for daily bread, that the playfulness inborn in every healthy plant can peep out but timidly and seldom. But when strife is exchanged for peace, when a plant is once safely sheltered behind a garden fence, then the struggles of the battlefield give place to the diversions of the garrison--diversions not infrequently hilarious enough. Now food abounds and superabounds; henceforth neither drought nor deluge can work their evil will; insect foes, as well as may be, are kept at bay; there is room in plenty instead of dismal overcrowding. The grateful plant repays the care bestowed upon it by bursting into a sportiveness unsuspected, and indeed impossible, amidst the alarms and frays incessant in the wilderness. It departs from parental habits in most astonishing fashion, puts forth blossoms of fresh grace of form, of new dyes, of doubled magnitude. The gardener's opportunity has come. He can seize upon such of these "sports" as he chooses and make them the confirmed habits of his wards. Take a stroll through his parterres and greenhouses, where side by side he shows you pansies of myriad tints and the modest little wild violets of kindred to the pansies' ancestral stock. Let him contrast for you roses, asters, tuberous begonias, hollyhocks, dahlias, pelargoniums, before cultivation and since. Were wild flowers clay, were the gardener both painter and sculptor, he could not have wrought marvels more glorious than these. In a few years the brethren of his guild have brought about a revolution for which, if possible at all to her, nature in the open fields would ask long centuries. And the gardener's experiments with these strange children of his have all the charm of surprise. No passive chooser is he of "sports" of promise, but an active matchmaker between flowers often brought together from realms as far apart as France and China. Sometimes his experiment is an instant success. Mr. William Paul, a famous creator of splendid flowers, tells us that at a time when climbing roses were either white or yellow, he thought he would like to produce one of bright dark colour. Accordingly he mated the Rose Athelin, of vivid crimson, with Russelliana, a hardy climber, and lo, the flower he had imagined and longed for stood revealed! But this hitting the mark at the first shot is uncommon good fortune with the gardener. No experience with primrose or chrysanthemum is long and varied enough to tell him how the crossing of two different stocks will issue. A rose which season after season opposes only indifference to all his pains may be secretly gathering strength for a bound beyond its ancestral paths which will carry it much farther than his hopes, or, perhaps, his wishes. Most flowers are admired for their own sweet sake, but who thinks less of an apple or cherry blossom because it bears in its beauty the promise of delicious fruit? Put a red Astrachan beside a sorry crab, a Bartlett pear next a tough, diminutive wild pear such as it is descended from, an ear of milky corn in contrast with an ear one-fourth its size, each grain of which, small and dry, is wrapped in a sheath by itself; and rejoice that fruits and grains as well as flowers can learn new lessons and remember them. At Concord, Massachusetts, in an honoured old age, dwells Mr. Ephraim W. Bull. In his garden he delights to show the mother vine of the Concord grape which he developed from a native wild grape planted as long ago as 1843. Another "sport" of great value was the nectarine, which was seized upon as it made its appearance on a peach bough. Throughout America are scattered experiment stations, part of whose business it is to provoke fresh varieties of wheat, or corn, or other useful plant, and make permanent such of them as show special richness of yield; earliness in ripening; stoutness of resistance to Jack Frost, or blight, or insect pests. Suppose that dire disaster swept from off the earth every cereal used as food. Professor Goodale, Professor Asa Gray's successor at Harvard University, has so much confidence in the experiment stations of America that he deems them well able to repair the loss we have imagined; within fifty years, he thinks, from plants now uncultivated the task could be accomplished. Among the men who have best served the world by hastening nature's steps in the improvement of flowers and fruits, stands Mr. Vilmorin, of Paris. He it was who in creating the sugar beet laid the foundation for one of the chief industries of our time. One of his rules is to select at first not the plant which varies most in the direction he wishes, but the plant that varies most in any direction whatever. From it, from the instability of its very fibres, its utter forgetfulness of ancestral traditions, he finds it easiest in the long run to obtain and to establish the character he seeks of sweetness, or size, or colour. Of flowering plants there are about 110,000, of these the farmer and the gardener between them have scarcely tamed and trained 1,000. What new riches, therefore, may we not expect from the culture of the future? Already in certain northern flower-pots the trillium, the bloodroot, the dog's-tooth violet, and the celandine are abloom in May; as June advances, the wild violet, the milkweed, the wild lily-of-the-valley, unfold their petals; later in summer the dog-rose displays its charms and breathes its perfume. All respond kindly to care, and were there more of this hospitality, were the wild roses which the botanist calls _blanda_ and _lucida_, were the cardinal flowers, the May flowers, and many more of the treasures of glen and meadow, made welcome with thoughtful study of their wants and habits, much would be done to extend the wealth of our gardens. Let a hepatica be plucked from its home in a rocky crevice where one marvels how it ever contrived to root itself and find subsistence. Transplant it to good soil, give it a little care--it asks none--and it will thrive as it never throve before; proving once again that plants do not grow where they like, but where they can. The Russian columbine rewards its cultivator with a wealth of blossoms that plainly say how much it rejoices in his nurture of it, in its escape from the frost and tempest that have assailed it for so many generations. But here we must be content to take a leaf out of nature's book, and look for small results unless our experiments are broadly planned. It is in great nurseries and gardens, not in little door-yards that "sports" are likely to arise, and to meet the skill which can confirm them as new varieties. Japan has much to teach us with regard to flowers: nowhere else on earth are they so sedulously cultivated, or so faithfully studied in all their changeful beauty. Perhaps the most striking revelation of the Japanese gardener is his treatment of flowering shrubs and flowering trees disposed in masses. Happy the visitors to Tokio who sees in springtime the cherry blossoms ready to lend their witchery to the Empress's reception! Much is done to extend the reign of beauty in a garden when it is fitly bordered with berry-bearers. Rows of mountain ash, snow-berry, and hawthorn trees give colour just when colour is most effective, at the time when most flowers are past and gone. In the practical bit of ground where the kitchen garden meets the flowers, Japan has long since enlarged its bill of fare with the tuber of a cousin of our common hedge nettle, with the roots of the large burdock, commoner still. In Florida, the calla lily has use as well as beauty; it is cultivated for its potato-like tubers. Much as the study of flowers heightens our interest in them, their first, their chief enduring charm consists in their simple beauty--their infinitely varied grace of form, their exhaustless wealth of changeful tints. Off we go with delight from desk and book to a breezy field, a wimpling brook, a quiet pond in woodland shade. A dozen rambles from May to October will show us all the floral procession, which, beginning with the trilliums and the violets, ends at the approach of frost with the golden-rod and aster. But who ever formed an engaging acquaintance without wishing it might become a close friendship? Never yet did the observant culler of bloodroot and columbine rest satisfied with merely knowing their names, and how can more be known unless flowers are set up in a portrait gallery of their own for the leisurely study of their lineaments and lineage? A word then as to the best way to gather wild flowers. A case for them in the form of a round tube, closed at the ends, with a hinged cover, can be made by a tinsmith at small cost. Its dimensions should be about thirty inches in length by five inches in diameter, with a strap attached to carry it by. At still less expense a frame can be made, or bought, formed of two boards, one-eighth of an inch thick, twenty-four inches long and eighteen inches broad, with two thin battens fastened across them to prevent warping. A quire of soft brown paper, newspaper will do, and a strap to hold all together, complete the outfit. Our gathered treasures at home, we may wish to deck a table or a mantel with a few of them. The lives of impressed blossoms can be, much prolonged by exercising a little care. Punch holes in a round of cardboard and put the stalks through these holes before placing the flowers in a vase. This prevents the stalks touching each other, and so decaying before their time. A little charcoal in the water tends to keep it pure; the water should be changed daily. A flower will fade at last be it tended ever so carefully. If we wish to preserve it dried we can best do so as soon as we bring it home, by placing it between sheets of absorbent paper (newspaper will do) well weighted down, the paper to be renewed if the plants are succulent and if there is any risk of mildew. But a dried plant after all is only a mummy. Its colours are gone; its form bruised and crumpled, gives only a faint suggestion of it as it lived and breathed. Other and more pleasant reminders of our summer rambles can be ours. With a camera of fair size it is easy to take pictures of flowers at their best; these pictures can be coloured in their natural tints with happy effect. In this art Mrs. Cornelius Van Brunt, of New York, has attained extraordinary success. Or, instead of the camera, why not at first invoke the brush and colour-box? Only a little skill in handling them is enough for a beginning. Practice soon increases deftness in this art as in every other, and in a few short weeks floral portraits are painted with a truth to nature denied the unaided pencil. For what flower, however meek and lowly, could ever tell its story in plain black and white? The amateur painter of flowers learns a good many things by the way; at the very outset, that drawing accurate and clear must be the groundwork of any painting worthy the name. Both in the use of pencil and brush there must be a degree of painstaking observation, wholesome as a discipline and delightful in its harvests. How many of us, unused to the task of careful observation, can tell the number of the musk-mallow's petals, or mark on paper the depth of fringe on a gentian, or match from a series of dyed silks the hues of a common buttercup? Drawing and painting sharpen the eye, and make the fingers its trained and ready servants. From the very beginning of one's task in limning bud and blossom, we see them richer in grace and loveliness than ever before. When wild flowers are sketched as they grow it is often easy to give them a new interest by adding the portraits of their insect servitors. Amateurs who are so fortunate as to visit the West Indies have an opportunity to paint the wonderful blossoms of the Marcgravia, whose minister, a humming bird, quivers above it like a bit of rainbow loosened from the sky. Early in the history of art the wild flowers lent their aid to decoration. The acanthus which gave its leaves to crest the capital of the Corinthian column, the roses conventionalized in the rich fabrics of ancient Persia, until they have been thought sheer inventions of the weaver, are among the first items of an indebtedness which has steadily grown in volume until to-day, when the designers who find their inspiration in the flowers are a vast and increasing host. In a modern mansion of the best type the outer walls are enriched with the leonine beauty of the sun-flower; within, the mosaic floors, the silk, and paper hangings, repeat themes suggested by the vine, the wild clematis and the Mayflower. The stained glass windows from New York, where their manufacture excels that of any other city in the world, are exquisite with boldly treated lilies, poppies, and columbines. In the drawing-room are embroideries designed by two young women of Salem, Massachusetts, who have established a thriving industry in transferring the glow of wild flowers to the adornment of noble houses such as this. As one goes from studio to studio, it is cheering to find so many men and women busy at work which is more joyful than play,--which in many cases first taken up as a recreation disclosed a vein of genuine talent and so pointed to a career more delightful than any other,--because it chimes in with the love of beauty and the power of giving it worthy expression. TRANSCRIBER'S NOTE: Unable to verify "partnery" nor "tucu-tucu", but they have been left as in the original. The word "sylvain" has been verified as a valid word, and therefore it has been left as in the original. 
39910	----	OMPHALOS: AN ATTEMPT TO UNTIE THE GEOLOGICAL KNOT. BY PHILIP HENRY GOSSE, F.R.S. WITH FIFTY-SIX ILLUSTRATIONS ON WOOD. [Greek: Auxanetai de ta zôa panta, osa echei omphalon, dia tou omphalou.] ARIST.; _Hist. Anim._ vii. 8. LONDON: JOHN VAN VOORST; PATERNOSTER ROW. 1857. LONDON: R. CLAY, PRINTER, BREAD STREET HILL. PREFACE. "You have not allowed for the wind, Hubert," said Locksley, in "Ivanhoe;" "or that had been a better shot." I remember, when I was in Newfoundland, some five-and-twenty years ago, the disastrous wreck of the brig _Elizabeth_, which belonged to the firm in which I was a clerk. The master had made a good observation the day before, which had determined his latitude some miles north of Cape St. Francis. A thick fog coming on, he sailed boldly by compass, knowing that, according to his latitude, he could well weather that promontory. But lo! about midnight the ship plunged right against the cliffs of Ferryland, thirty miles to the south, crushing in her bows to the windlass; and presently went down, the crew barely saving their lives. The captain _had not allowed for the polar current_, which was setting, like a sluice, to the southward, between the Grand Bank and the land. When it was satisfactorily ascertained that the heavenly body, now known as Uranus, was a planet, its normal path was soon laid down according to the recognised law of gravitation. But it would not take this path. There were deviations and anomalies in its observed course, which could in nowise be referred to the operation of any known principle. Astronomers were sorely puzzled to explain the irregularities, and to reconcile facts with laws. Various hypotheses were proposed: some denied the facts; that is, the observed places of the planet, boldly assuming that the observers had been in error: others suggested that perhaps the physical laws, which had been supposed to govern the whole celestial machinery, did not reach so far as Uranus's orbit. The secret is now known: _they had not allowed for the disturbances produced by Neptune_. In each of these cases the conclusions were legitimately deduced from the recognised premises. Hubert's skilled eye had calculated the distance; his experience had taught him the requisite angle at which to shoot, the exact amount of force necessary, and every other element proper to insure the desired result, _except one_. There was an element which he had overlooked; and it spoiled his calculations. _He had forgotten the wind._ The master of the ill-fated brig had calculated his latitude correctly; he knew the rate of his vessel's speed; the compass had showed him the parallel on which to steer. These premises ought to have secured a safe conclusion; and so they would, but for an unrecognised power that vitiated all; he was not aware of the silent and secret current, that was every hour setting him to the south of his supposed latitude. The path of Uranus had been calculated by the astronomers with scrupulous care, and every known element of disturbance had been considered; not by one, but by many. But for the fact that the planet had been previously seen in positions quite inconsistent with such a path, it would have been set down as beyond controversy correct. Stubborn fact, however, would not give way; and hence the dilemma, till Le Verrier suggested the unseen antagonist. I venture to suggest in the following pages an element, hitherto overlooked, which disturbs the conclusions of geologists respecting the antiquity of the earth. Their calculations are sound on the recognised premises; _but they have not allowed for the Law of Prochronism in Creation_. The enunciation of this principle will lie in a nut-shell; the reader will find it at p.124; or p.347. All the rest of the book is illustration. I do not claim originality for the thought which I have here endeavoured to work out. It was suggested to me by a Tract, which I met with some dozen years ago, or more; the title of which I have forgotten: I am pretty sure it was anonymous, but it was published by Campbell, of 1, Warwick Square. Whether it is still in print I do not know; I never saw another copy. If the author is alive, and if he should happen to cast his eye on this volume, he will doubtless recognise his own bantling, and accept this my acknowledgment. The germ of the argument, however, I have found, since these pages were written, in "The Mineral and Mosaical Geologies," of Granville Penn (1822). The state of physical science when he wrote did not enable him to press the argument to a demonstration, as I have endeavoured to do; for he could not refer to structural peculiarities as sensible records of past processes, _inseparable from newly created organisms_. I would not be considered as an opponent of geologists; but rather as a co-searcher with them after that which they value as highly as I do, TRUTH. The path which I have pursued has led me to a conclusion at variance with theirs. I have a right to expect that it be weighed; let it not be imputed to vanity if I hope that it may be accepted. But what I much more ardently desire is, that the thousands of thinking persons, who are scarcely satisfied with the extant reconciliations of Scriptural statements and Geological deductions,--who are silenced but not convinced,--may find, in the principle set forth in this volume, a stable resting-place. I have written it in the constant prayer that the God of Truth will deign so to use it; and if He do, to Him be all the glory! P. H. G. MARYCHURCH, TORQUAY, _October, 1857_. CONTENTS. I THE CAUSE. Evidence of the Senses often delusive--Deductions of Reason fallible--Essentials sometimes overlooked--Discrepancy between Scripture and Geological Conclusions--Painful Dilemma--Efforts to escape from it--Supremacy of Truth--Various Attempts at Reconciliation--Denouncers--Opinions of Brown--Blackwood--Macbrair--Ure--Penn--Young--Cockburn-- Miller--Sedgwick--Turner--Sumner--Chalmers--Harris--Gray-- Conybeare--Hitchcock--Pye Smith--"Protoplast"--Babbage-- Powell--"Vestiges"--Amplitude of Choice _Page_ 1-29 II. THE WITNESS FOR THE MACRO-CHRONOLOGY. A Court of Inquiry--The Witnesses--Testimony of One--Strata of Thames Tunnel--of Hertfordshire--of Yorkshire--of the Globe--Granite--Granitic Strata--Organic Remains--Silurian System--Corals--Trilobites--Mollusks--Devonian System--Old Red Sandstone--Its Formation--Fishes--Carboniferous System--Coral Limestone--Millstone Grit--Coal--Predominance of Carbonic Acid--Extent and Thickness of Coal-Fields--Formation of Coal--Conjecture as to its Age--Antediluvian Theory untenable--Sauroid Fishes--Earliest Reptiles--Footprints of Frogs 30-53 III. THE SAME--(_continued_.) Disturbances of Strata--Internal Heat--Changes of Land and Sea--New Red Sandstone--Footprints--Labyrinthodon--Lias Formation--Crinoids--Ammonites--Belemnites--Fishes--Marine Reptiles--Ichthyosaur--Plesiosaur--European Archipelago--Oolitic Formation--Cycads--Megalosaur-- Bat-Lizards--Iguanodon--Hylæosaur--Earliest Mammal--Chalk Formation--Infusoria--Diatomaceæ--Their Minuteness and Numbers--Chambered Cephalopods--Mosasaur--End of Secondary Formations--Convulsions--Basalt--Uprearing of Mountain Chains--London Clay--Plants and Animals--Fishes--Reptiles--Birds--Mammals--Anoplotherium--Condition of Europe--Dinotherium--Mastodon--Mammoth--Trees--Crag Formation--Tertiary Fauna--Bone Caves--Kirkdale--Erratic Blocks--Glaciers--Sloths--Marsupials--Birds--Raised Beaches--Human Period--Moho--Present Cosmical Operations--River Deltas--Coral Beefs--Volcanoes--Changes of Level--Earthy Deposits--Stalagmite--Shells--Recapitulation. 54-101 IV. THE CROSS-EXAMINATION. Grandeur of the Evidence--Proposed Line of Objection--It is but circumstantial--Example of Confusion of Thought--Analysis of the Reasoning---Dependent on the exhaustive Power of Observation--Relation of Precedence and Sequence--Of Cause and Effect--Force of my Position. 102-109 V. POSTULATES. The Creation of Matter--The Persistence of Species. 110-112 VI. LAWS. The Course of Nature a Circle--Illustrations--Scarlet Runner--Lady-fern--Hawkmoth--Plumularia--Cow--Universality of the Law--Creation an Irruption into a Circle--False Witness to Past Processes--Prochronism and Diachronism--Phenomena illusory--Recapitulation 113-126 VII. PARALLELS AND PRECEDENTS. (_Plants._) Ideal Tour on Creation-Day--Chronological Investigations--Queried Age of a Tree-fern--Data for the Inquiry--Development of the Leaves--Leaf-scars--Report--Its manifest Error--Selaginella--Bamboo-- Couch-grass--Screw-pine--Pashiuba--Sugar Palm--Areca--Rattan--Agave--Traveller's Tree--Butterfly Flower--Orchis--Gladiolus--Grass-tree--White Lily--Testudinaria--Caffer-Bread--Fig--Banyan--Euphorbia-- Tulip-tree--Bignonia--Loranthus--Prickly Pear--Mangrove--Silk-cotton-tree--Locust-tree--Restriction of the Inquiry--Uniform Testimony to Untruth 127-181 VIII. PARALLELS AND PRECEDENTS. (_Invertebrate Animals._) Resumption of the Examination--SeaPen--Millepore-- Madrepore--Organ-pipe--Medusa--Sea-urchin--Feather-star-- Tapeworm--Serpula--Terebella--White-ant--Goliath-beetle-- Gnat--Case-fly--Melicerta--Julus--Buprestis--Shore-crab-- Barnacle--Lepralia--Botryllus--Clavagella--Prickly Venus--Scorpion Stromb--Tiger Cowry--Thorny Murex--Pearly Nautilus--Cuttlefish 182-239 IX. PARALLELS AND PRECEDENTS. (_Vertebrate Animals._) Examination of the Vertebrata--Sword-fish--Gilt-head-- Laminæ of Scales--Shark--Arrangement of Teeth--Their Structure--Tree-frog--Metamorphosis--Rattlesnake-- Crocodile--Tortoise--Laminæ of Plates--Skull of Cassowary--Peacock--Humming-bird--Trogon--Structure and Growth of Feathers--Whalebone of Whale--Horn of Ibex--Horn of Stag--Teeth of Horse--Of Babiroussa--Of Hippopotamus--Tusk of Elephant--Molars of Elephant 240-273 X. PARALLELS AND PRECEDENTS. (_Man._) Examination of Primal Man--Blood--Its Formation--Its Oxygenation--Nails--Hair--Bones--Teeth--All formed by successive Processes--Stature--Thyroid Cartilage--Beard--Development of Teeth--Proportion of Bloods--Condition of Skeleton--Navel--False Conclusion 274-291 XI. PARALLELS AND PRECEDENTS. (_Germs._) Assumption of adult Development at Creation--Its Reasonableness--The Position waived--Assumption of the Germ-Hypothesis--Double Cocoa-nut--Coral Tree--Tulip--Earth-pea--Mangrove--Medusa--Connexion of Germs with Parent--In Echinoderms--In Annelids--In Insects--Egg of Butterfly--Of Nut Weevil--Of Bots--Of Ichneumon--Of Pill Chafer--Of Gall-fly--Of Lace-fly--Of Spider--Of Gipsy Moth--Of Coccus--Of Saw-fly--Of Cockroach--Of Dirt-dauber--Metamorphosis of Star-fish--Eggs attached to Brachionus--Viviparous Progeny of Rotifer--Of Asplanchna--Of Daphnia--Egg-purse of Shark--Economy of Surinam Toad--Egg of Fowl--Foetus of Kangaroo--Umbilicus 292-334 XII. THE CONCLUSION. Uniformity of Results--Prochronism of Organic Nature--Phenomena inadequate to settle Chronology--Historic Testimony alone oracular--Familiar Illustration--Objections met--Analogy between an Organism and a World--Illustration from a Tree--Analogy between the Life of a Species and that of an Individual--History Divinely Projected--Grand Plan of Nature--Diachronic Existence not necessary--Deceptive Phenomena inseparable from Created Organisms--Illustrations abundant--Hypothesis of the Life-history of the Globe--Supposition of 1857 being the Era of Creation--What its State?--Minuteness and Verity of Proofs of Life present no Difficulty--Coprolites--Fæcal Residua in newly-created Animals--_Cyclical_ not _Organic_ Condition the Test of Prochronism--Illustrations from the inorganic World--Rivers--Ocean Currents--Celestial Bodies--Velocity of Light--Records of Entities actually passed--"No Tree has Leaves"--Plates of Testudinaria--Leaf-scars of Palm--Column of Nerita--Spines of Murex--Madreporic Plate of Cribella--Hilum of Seed--Navel of Mammal--Argument of "Great and Small"--Old Hypothesis of _Lusus Naturæ_--Demonstration of a Law--Effect of this Principle on the Study of Geology--Summing up 335-372 LIST OF ILLUSTRATIONS. PAGE Geological Section of Yorkshire 35 Calymene Blumenbachii 41 Cephalaspis 44 Labyrinthodon 57 Snake-necked Marine Lizards 59 Megalosaurus Bucklandi 61 Bat-lizards 62 Hylæosaurus armatus 63 Mammoth 74 Moho 84 Germination of Scarlet-runner 114 Diagram of Bean 116 " Fern 117 " Hawkmoth 119 " Polype 120 " Cow 121 Leaf-scars of Tree-fern 132 Roots of Iriartea 139 Traveller's Tree 148 Corm of Gladiolus 153 Section of Lily-bulb 157 Testudinaria 159 Encephalartos 162 Twig of Tulip-tree 167 Young Plant of Loranthus 171 Silk-cotton Tree 175 Section of Exogenous Tree 179 Muricated Madrepore 185 Organ-pipe 187 Comatula and Young 194 Serpula 200 Goliath Beetle and Pupa case 206 Larva of Case-fly 209 Melicerta 210 Lepas 218 Botryllus 224 Clavagella 226 Dione Veneris 228 Murex tenuispina 233 Scale of Gilt-head 242 Plates of Tortoise 251 Growth of a Feather 254 Horns of Stag 258 Skull of Babiroussa 262 Skull of Hippopotamus 265 Skull of Elephant 267 Growth of Hair 278 Section of Human Tooth 282 Garden Tulip 298 Germination of Earth-pea 300 Seed of Mangrove 303 Lace-fly and Eggs 312 Brachionus with Eggs 322 Pregnant Asplanchna 323 Hen's Egg 329 Gyroceras 371 [Greek: HO OMPHALOS.] I. THE CAUSE. "Is there not a cause?"--1 SAM. xvii. 29. An eminent philosopher has observed that "nothing can be more common or frequent than to appeal to the evidence of the senses as the most unerring test of physical effects. It is by the organs of sense, and by these alone, that we can acquire any knowledge of the qualities of external objects, and of their mutual effects when brought to act one upon another, whether mechanically, physically, or chemically; and it might, therefore, not unreasonably be supposed, that what is called the evidence of the senses must be admitted to be conclusive, as to all the phenomena developed by such reciprocal action. "Nevertheless, the fallacies are numberless into which those are led who take what they consider the immediate results of sensible impressions, without submitting them to the severe control and disciplined analysis of the understanding."[1] If this verdict is confessedly true with regard to many observations which we make on things immediately present to our senses, much more likely is it to be true with respect to conclusions which are not "the immediate results of sensible impressions," but are merely deduced by a process of reasoning from such impressions. And if the direct evidence of our senses is to be received with a prudent reserve, because of this possibility of error, even when we have no evidence of an opposing character, still more necessary is the exercise of caution in judging of facts assumed to have occurred at a period far removed from our own experience, and which stand in contradiction (at least apparent, _primâ facie_, contradiction) to credible historic testimony. Nay, the caveat acquires a greatly intensified force, when the testimony with which the assumed facts are, or seem to be, at variance, is no less a testimony than His who ordained the "facts," who made the objects of investigation; the testimony of the Creator of all things; the testimony of Him who is, from eternity to eternity, "[Greek: HO APSEUDÊS THEOS]"! I hope I shall not be deemed censorious in stating my fear that those who cultivate the physical sciences are not always sufficiently mindful of the "_Humanum est errare_." What we have investigated with no little labour and patience, what we have seen with our eyes many many times, in many aspects, and under many circumstances, we naturally believe firmly; and we are very prone to attach the same assurance of certainty to the inferences we have, _bonâ fide_, and with scrupulous care to eliminate error, deduced from our observations, as to the observations themselves; and we are apt to forget that some element of error may have crept into our actual investigations, and still more probably into our deductions. Even if our observations be so simple, so patent, so numerous, as _almost_ to preclude the possibility of mistake in them, and our process of reasoning from them be without a flaw, still we may have overlooked a principle, which, though perhaps not very obvious, ought to enter into the investigation, and which, if recognised, would greatly modify our conclusions. In this volume I venture to suggest such a principle to the consideration of geologists. It will not be denied that Geology is a science that stands peculiarly in need of being cultivated with that salutary self-distrust that I have above alluded to. Though a strong and healthy child, it is as yet but an infant. The objects on which its senses have been exercised, its [Greek: ta blepomena], are indeed plain enough and numerous enough, when once discovered; but the inferences drawn from them, its [Greek: bebaia], find their sphere in the most venerably remote antiquity,--an antiquity mensurable not by years or centuries, but by _secula seculorum_. And the dicta, which its votaries rest on as certitudes, are at variance with the simple literal sense of the words of God. I am not assuming here that the Inspired Word has been rightly read; I merely say that the plain straightforward meaning, the meaning that lies manifestly on the face of the passages in question, is in opposition with the conclusions which geologists have formed, as to the antiquity and the genesis of the globe on which we live. Perhaps the simple, superficial sense of the Word is not the correct one; but it is at least that which its readers, learned and unlearned, had been generally content with before; and which would, I suppose, scarcely have been questioned, but for what appeared the exigencies of geological facts. Now while there are, unhappily, not a few infidels, professed or concealed, who eagerly seize on any apparent discrepancy between the works and the Word of God, in order that they may invalidate the truth of the latter, there are, especially in this country, many names of the highest rank in physical (and, among other branches, in geological) science, to whom the veracity of God is as dear as life. They cannot bear to see it impugned; they know that it cannot be overthrown; they are assured that He who gave the Word, and He who made the worlds, is One Jehovah, who cannot be inconsistent with Himself. But they cannot shut their eyes to the startling fact, that the records which _seem_ legibly written on His created works do flatly contradict the statements which _seem_ to be plainly expressed in His word. Here is a dilemma. A most painful one to the reverent mind! And many reverent minds have laboured hard and long to escape from it. It is unfair and dishonest to class our men of science with the infidel and atheist. They did not rejoice in the dilemma; they saw it at first dimly, and hoped to avoid it.[2] At first they believed that the mighty processes which are recorded on the "everlasting mountains" might not only be harmonized with, but might afford beautiful and convincing demonstrations of Holy Scripture. They thought that the deluge of Noah would explain the stratification, and the antediluvian era account for the organic fossils. As the "stone book" was further read, this mode of explanation appeared to many untenable; and they retracted their adherence to it. To a mind rightly constituted, Truth is above every thing: there is no such thing as a pious fraud; the very idea is an impious lie: God is light, and in Him is no darkness at all; and that religion which can be maintained only by dissembling or denying truth, cannot proceed from "Him that is Holy, Him that is True," but from him who "is a liar, and the father of it." Many upright and ardent cultivators of the young science felt that truth would be compromised by a persistence in those explanations which had hitherto passed current. The discrepancy between the readings in Science and the hitherto unchallenged readings in Scripture, became manifest. Partisans began to array themselves on either side; some, jealous for the honour of God, knew little of science, and rushed into the field ill-prepared for the conflict; some, jealous for science, but little conversant with Scripture, and caring less for it, were willing to throw overboard its authority altogether: others, who knew that the writings were from the same Hand, knew therefore that there must be some way of reconciling them, and set themselves to find it out. Have they succeeded? If I thought so, I would not publish this book. Many, I doubt not, have been convinced by each of the schemes by which the discrepant statements have been sought to be harmonized. Each of them has had sufficient plausibility to convince its propounder; and, probably, others too. And some of them have attained a large measure of public confidence. Yet if any one of them is true, it certainly has not commanded universal assent. Let us examine how far they agree among themselves, who propose to reconcile Scripture and Science, "the Mosaic and the Mineral Geologies." And first, it is, perhaps, right to represent the opinions of those who stand by the literal acceptation of the Divine Word. There have been some, indeed, who refuse to entertain the question of reconciliation, taking the high ground that, as the Word of God is and must be true, it is impious to set any evidence in competition with it. I cannot but say, my sympathies are far more with these than with those who, at the opposite pole of the argument, would make scientific deduction paramount, and make the Word go to the wall. But, then, we ought to be quite sure that we have got the very Word of God; and, so far from being impious, it seems highly proper and right, when conflicting evidence appears to flow out of what is indubitably God's _work_, to examine afresh the witnesses on both sides, that we may not make either testify what it does not. Those good men who merely _denounce_ Geology and geologists, I do not quote. There are the facts, "written and engraven in stones," and that by the finger of God. How can they be accounted for? Some have recourse to the assumption that the natural processes by which changes in the earth's surface are now going on, may have operated in antediluvian times with a rapidity and power of which we can form little conception from what we are cognisant of. The Rev. J. Mellor Brown takes this ground, adducing the analogies of steam-power and electricity, as effecting in a few moments or hours, what formerly would have required several days or weeks to accomplish. "God's most tremendous agencies may have been employed in the beginning of his works. If, for instance, it should be conceded that the granitic or basaltic strata were once in a state of fusion, there is no reason why we should not call in the aid of supposition to produce a _rapid_ refrigeration. We may surround the globe with an atmosphere (not as yet warmed by the rays of the newly kindled sun) more intensely cold than that of Saturn. The degree of cold may have been such as to cool down the liquid granite and basalt in a few hours, and render it congenial to animal and vegetable life; while the gelid air around the globe may have been mollified by the abstracted caloric."[3] A writer in Blackwood (xli. 181; xlii. 690), in like manner, adheres to the literal sense of Genesis and the Decalogue, and alludes to "the great agencies--the magnetic, electrical, and ethereal influences--probably instrumental in all the phenomena of nature," as being far more powerful than is generally suspected. Mr. Macbrair--who does not, however, appear, from the amount of his acquaintance with science, competent to judge of the physical evidence--supposes stratification to have proceeded with immense rapidity, because limestone is now deposited in some waters at the rate of six inches per annum. Because a mass of timber, ten miles in length, was collected in the Mississippi, in thirty-eight years, he considers that a "capital coal field" might be formed in a single century. Alluvial strata are mud lavas ejected from volcanoes. The whole difficulty of fossil remains is got rid of by ignoring the distinctions of species, and assuming that the ancient animals and the recent ones are identical. The Pterodactyle and the Plesiosaurus he does not allude to.[4] According to Dr. Ure,--"The demiurgic week ... is manifestly composed of six working days like our own, and a day of rest, each of equal length, and, therefore, containing an evening and a morning, measured by the rotation of the earth round its axis.... Neither reason nor revelation will justify us in extending the origin of the material system beyond six thousand years from our own days. The world then received its substance, form, and motions from the volition of the Omnipotent." His theory of the stratification extends over the whole antediluvian era. He supposes that successive irruptions of the central heat broke up the primitive strata and deposited the secondary and tertiary. "The basaltic or trap phenomena lead to the conclusion that such upheavings and subversions were not confined to one epoch of the antediluvian world, but that, coeval with its birth, they pervaded the whole period of its duration.... The Deluge--that universal transflux of the ocean--was the last and greatest of these terraqueous convulsions."[5] Another class of this school of interpreters refers the stratification of the earth, either to the deluge alone, or to that convulsion conjoined with the one which is considered to have taken place on the third day of the Mosaic narrative. Perhaps the most eminent writer of this class is Mr. Granville Penn, whose opinions may be thus condensed. He supposes that this globe has undergone only two revolutions. The first was the violent rupture and depression of the surface to become the bed of the sea, and the simultaneous elevation of the other portion to become dry land,--the theatre of terrestrial existence. This first revolution took place before the creation of any organized beings. The second revolution was at the Noachic Flood, when the former bed of the sea was elevated to become the dry land, with all its organic accumulations of sixteen centuries, while the former land was correspondingly depressed and overflowed. "The earth must, therefore, necessarily exhibit manifest and universal evidences of the vast apparent ruin occasioned by its first violent disruption and depression; of the presence and operation of the marine fluid, during the long interval which succeeded; and of the action and effects of that fluid in its ultimate retreat."[6] Mr. Fairholme[7] so nearly agrees with the above, that I need not quote his opinions in detail. Another class, represented by Dr. Young and the Rev. Sir W. Cockburn, Dean of York, have maintained with considerable power, backed by no mean geological knowledge, that the deluge is a sufficient _vera causa_ for the stratification of the globe, and for the fossilization of the organic remains. Dr. Young supposes that an equable climate prevailed all over the globe in the antediluvian period. "Were the highest mountains transferred to the equatorial regions, the most extensive oceans removed towards the poles, and fringed with a border of archipelago,--while lands of moderate height occupied most of the intermediate spaces, between these archipelagos and the equatorial mountains; then a temperature, almost uniform, would prevail throughout the world." This "perpetual summer" would account for the prodigious quantities of animal and vegetable remains:--every region teemed with life. At the Flood, "the bed of the ocean must have been elevated, and the dry land at the same time depressed," an expansive force acting from below to heave up the ocean's bed. To this agency are attributed the vast masses of granite, gneiss, basalt, and other rocks of igneous origin, which seem to have been forced upwards in a state of fusion, into their present lofty stations. The ancient bed of the ocean may have consisted of numerous layers of sand, clay, lime, and other substances, including corals and marine shells,--to a certain degree consolidated into rocks. By the progressive rising of the waters and the currents so made, fresh materials would be conveyed to the depths of the ocean, so that the magnesian limestone, the saliferous beds, the lias, &c., would be deposited.[8] The Dean of York, in like manner, considers that the convulsions produced by the Deluge, are sufficient to account for all the stratification and fossil remains. That the gradual rise of the waters, and their penetration into the recesses of the rocks, would cause successive volcanic eruptions; the earlier of which would inclose marine fishes and reptiles; then others in turn, the pachyderms and great reptiles of the plains; and, finally, the creatures more exclusively terrestrial. That these repeated heavings of mighty volcanoes raised great part of what had been the bottom of the sea, above its level, and that hence the present land had been for sixteen centuries under water. That the animals which entered the ark, were not selected till after many species had already perished in the earlier convulsions, and hence the number of extinct species now exhumed.[9] My reader will kindly bear in mind that I am not examining these opinions; I adduce them as examples of the diversity of judgment that still prevails on a question which some affect to consider as settled beyond the approach of doubt. A totally different solution of the difficulty has been sought in the hypothesis, that the six "days" of the Inspired Record signify six successive periods of immense though of undefined duration. This opinion is as old as the Fathers at least,[10] and not a few able maintainers of it belong to our own times. It has been put forth, however, with most power, by a late lamented geologist, whose wonderful vigour of description and felicity of illustration, have done, perhaps, more than the efforts of any other living man, to render his favourite science popular. Perhaps I can scarcely set his views in a more striking light than he himself has done in his own peculiarly graphic report of a conversation, which he sustained with some humble inquirers in the Paleontological Gallery of the British Museum. "I last passed," says Mr. Hugh Miller, "through this wonderful gallery at the time when the attraction of the Great Exhibition had filled London with curious visitors from all parts of the empire; and a group of intelligent mechanics, fresh from some manufacturing town in the midland counties, were sauntering on through its chambers immediately before me. They stood amazed beneath the dragons of the Oolite and Lias; and, with more than the admiration and wonder of the disciples of old, when contemplating the huge stones of the Temple, they turned to say, in almost the old words, 'Lo! master, what manner of great beasts are these?' 'These are,' I replied, 'the sea-monsters and creeping things of the second great period of organic existence.' The reply seemed satisfactory, and we passed on together to the terminal apartments of the range appropriated to the tertiary organisms. And there, before the enormous mammals, the mechanics again stood in wonder, and turned to inquire. Anticipating the query, I said, 'And these are the huge beasts of the earth, and the cattle of the third great period of organic existence; and yonder in the same apartment, you see, but at its farther end, is the famous fossil Man of Guadaloupe, locked up by the petrifactive agencies in a slab of limestone.' The mechanics again seemed satisfied; and, of course, had I encountered them in the first chamber of the suite, and had they questioned me respecting the organisms with which _it_ is occupied, I would have told them that they were the remains of the herbs and trees of the _first_ great period of organic existence. But in the chamber of the mammals we parted, and I saw them no more."[11] A large and influential section of the students of Geology regard this hypothesis as untenable. Generally they may be described as holding that the history which is recorded in the igneous and fossiliferous strata does not come into the sacred narrative in any shape. As, however, that narrative commences with "the beginning," and comes down to historic times, the facts so recorded must find their chronology within its bounds. Their place is accordingly fixed by this school of interpretation between the actual primordial creation (Gen. i. 1), and the chaotic state (ver. 2). Let us hear an able and eloquent geologist, Professor Sedgwick, on the hypothesis just mentioned of the elongation of the six days:-- "They [certain excellent Christian writers on the subject of Geology] have not denied the facts established by this science, nor have they confounded the nature of physical and moral evidence; but they have prematurely (and, therefore, without an adequate knowledge of all the facts essential to the argument) endeavoured to bring the natural history of the earth into a literal accordance with the Book of Genesis; first, by greatly extending the periods of time implied by the six days of creation; and secondly, by endeavouring to show that under this new interpretation of its words, the narrative of Moses may be supposed to comprehend, and to describe in order, the successive epochs of Geology. It is to be feared that truth may, in this way, receive a double injury; and I am certain that the argument just alluded to has been unsuccessful."--"We must consider the old strata of the earth as monuments of a date long anterior to the existence of man, and to the times contemplated in the moral records of his creation."[12] Many able theologians, who, though well acquainted with natural science, can scarcely be considered as geologists, have been satisfied with this solution of the problem. Thus Sharon Turner:-- "What interval occurred between the first creation of the material substance of our globe, and the mandate for light to descend upon it, whether months, years, or ages, is not in the slightest degree noticed [in the Sacred Record]. Geology may shorten or extend its duration, as it may find proper."[13] Thus the present Archbishop of Canterbury:-- "We are not called upon to deny the possible existence of previous worlds, from the wreck of which our globe was organized, and the ruins of which are now furnishing matter for our curiosity."[14] Thus Dr. Chalmers:-- "The present economy of terrestrial things was raised about six thousand years ago on the basis of an earth then without form and void; while, for aught of information we have in the Bible, the earth itself may before this time have been the theatre of many lengthened processes, the dwelling-place of older economies that have now gone by, but whereof the vestiges subsist even to the present day, both to the needless alarm of those who befriend Christianity, and the unwarrantable triumph of those who have assailed it."[15] Thus Dr. Harris:-- "The first verse of Genesis was designed to announce the absolute origination of the material universe by the Almighty Creator; and, passing by an indefinite interval, the second verse describes the state of our planet immediately prior to the Adamic creation; and the third verse begins the account of the six days' work."[16] Thus Mr. Gray:-- "That an antecedent state of the earth existed before the recorded Mosaical epoch, will clearly come out to view by the consideration of the terms used in the second verse. There was at that period, according to the express Mosaic record, anterior to the six days' reduction into order, _existing earth_ and _existing water_."[17] Probably the majority of our ablest geologists, men who have devoted their lives to the study and elucidation of geological phenomena, are to be found among those who advocate this scheme of reconciling those phenomena with the statements of the Holy Scriptures. Thus one of the earliest cultivators of the science, the Rev. Dr. Conybeare:-- "I regard Gen. i. 1 as an universal proposition, intended to contradict all the heathen systems which supposed the eternity of matter or polytheism; and ver. 2 I regard as proceeding to take up our planet in a state of ruin from a former condition, and describing a succession of phenomena effected in part by the laws of nature (which are no more than our expression of God's observed method of working), and in part by the immediate exercise of Divine power in directing and creating."[18] Dr. Hitchcock, President of Amherst College, U.S., gives in his adhesion to this principle. After summing up the evidence in favour of the earth's high antiquity, he inquires, "Who will hesitate to say that it ought to settle the interpretation of the first verse of Genesis, in favour of that meaning which allows an intervening period between the creation of matter and the creation of light? This interpretation of Genesis is entirely sufficient to remove all apparent collision between Geology and revelation. It gives the geologist full scope for his largest speculations concerning the age of the world. It permits him to maintain that its first condition was as unlike to the present as possible, and allows him time enough for all the changes of mineral constitution and organic life which its strata reveal. It supposes that all these are passed over in silence by the sacred writers, because irrelevant to the object of revelation; but full of interest and instruction to the men of science who should afterwards take pleasure in exploring the works of God. "It supposes the six days' work of creation to have been confined entirely to the fitting up the world in its present condition, and furnishing it with its present inhabitants. Thus, while it gives the widest scope to the geologist, it does not encroach upon the literalities of the Bible; and hence it is not strange that it should be almost universally adopted by geologists, as well as by many eminent divines."[19] Dr. Pye Smith, accepting the immense undefined interval between the event of the first verse, and the condition chronicled in the second, held the somewhat remarkable opinion that the term "earth" in that verse, and throughout the whole description of the six days, is "designed to express the part of our world which God was adapting for the dwelling of man and the animals connected with him." And that portion he conceived to have been "a part of Asia, lying between the Caucasian ridge, the Caspian Sea, and Tartary on the north, the Persian and Indian Seas on the south, and the high mountain ridges which run at considerable distances on the eastern and western flank." The whole of the six days' creation was confined, on this hypothesis, to the re-stocking, with plants and animals, of this limited region after an inundation caused by its subsidence. The flood of Noah was nothing more than a second overflowing of the same region, by "an elevation of the bed of the Persian and Indian Seas, or a subsidence of the inhabited land towards the south."[20] The author of "The Protoplast" has made the very original suggestion, that the geological periods may have occurred during the paradisaical condition of man, which he thinks was of an indefinitely protracted duration, human chronology commencing at the Fall. "We have no data in Scripture from which to gather certain information, and Adam may have lived unfallen _one day_, or _millions of years_." The years of the first man's mortal life began to be reckoned when his immortality ceased. He was nine hundred and thirty years _old_:[21] he had been nine hundred and thirty years gradually decaying, slowly dying. "It may, indeed, be said that no man could have survived those convulsions of nature, of which traces have been discovered in the earth's crust. I would reply to this;--First, that we have no reason to suppose that these changes affected the whole globe _at once_; they may have been _partial and successive_; and the world's Eden may have been a spot peculiarly exempted from their influence. Secondly, that Adam's body before the fall was not constituted as ours now are; it was incorruptible and immortal: physical phenomena could have had no deleterious effect upon him." "Why should we find any difficulty in supposing that the geological changes which appear to have passed upon the globe, _after_ its creation, and _before_ its curse, were to the first man sources of ever-renewing admiration, delight, and advantage? "Inclining to the belief that both the animal fell and the animal curse were considerably antecedent to the sin of Adam, I see no difficulty in the admission, that animal death may also have prevailed prior to that event."[22] While all those writers whose opinions I have cited, feel it more or less incumbent on them to seek a reconciliation between the words of Inspiration and the phenomena of Geology, there are not a few who decline the task altogether. Some eminent in science seem, by their entire avoidance of the question, to allow judgment to go by default. Others more boldly deny that the two can be accommodated. Mr. Babbage appears to think the archaic Hebrew so insuperably obscure a language, that no confidence can be put in our constructions of its statements; an opinion which, if true, would make the revelation of God to us, with all its glorious types, and promises, and prophecies, more dubious than the readings of Egyptian papyri, or the decipherment of Assyrian cuneiforms. On this notion, however, Dr. Pye Smith observes:--"All competent scholars, of whatever opinions and parties they may be in other respects, will agree to reject any imputation of uncertainty with respect to the means of ascertaining the sense of the language." Others find no difficulty in understanding the Hebrew, but in believing it. Professor Baden Powell sees in the plain, unvarnished narrative of the Holy Spirit, only myth and poetry: it "was not intended for an historical narrative" at all; and he thinks (I hope incorrectly), that there is a pretty general agreement with his views. "Most rational persons," he says, "now acknowledge the failure of the various attempts to reconcile the difficulty [between Geology and Scripture] by any kind of verbal interpretation; they have learnt to see that the 'six days of thousands of years' have, after all, no more correspondence with anything in Geology than with any sane interpretation of the text. And that the 'immense period at the beginning,' followed by a recent literal great catastrophe, and final reconstruction in a week, is, if possible, more strangely at variance with science, Scripture, and common sense. Yet while they [viz. the 'rational persons,'] thus view the labours of the Bible-geologists as fruitless attempts, they often do not see--," &c. &c.[23] Of course this gives up the authority of Scripture altogether; and, consistently enough, the author is severe upon the prevalent "indiscriminate and unthinking Bibliolatry." "If in any instance the letter of the narrative or form of expression may be found _irreconcilably at variance with physical truth_,[24] we may allow, to those who prefer it, the alternative of understanding them either as religious truths, represented under sensible images, or as descriptions of events according to the preconceptions of the writers, or the traditions of the age." The author of "Vestiges of the Natural History of Creation" propounds a theory of organic origin much more worthy of God, than that "mean view," which supposes Him "to come in on frequent occasions with new fiats or special interferences." Coolly bowing aside His authority, this writer has hatched a scheme, by which the immediate ancestor of Adam was a Chimpanzee, and his remote ancestor a Maggot! * * * * * In reviewing this array of opinions, is there not sufficient ground for regarding with caution the claim to certainty which has been boldly put forth for the conclusions of Geology? It cannot be denied that there is here room for a very considerable amplitude of choice among discordant hypotheses. All cannot be true, unless on the principle which was claimed for the Church by the Council of Trent--"_Cum enim ecclesia duarum expositionum ubertate gaudeat, non esse eam ad unius penuriam restrigendam!_" I do not for a moment intend to put all these hypotheses and assumptions on the same level. They vary widely as to their tenableness, and as to their prevalence. But if we leave out of view the fears of those who, from insufficient acquaintance with science, are not competent to adjudicate on its positions, and those who despise or decline Biblical authority altogether on this subject, we have still a somewhat wide range to choose from. Shall we accept the _antediluvian_, or the _diluvian_ stratification? the six _ages_ or the six _days_ of creation? the irruptions of internal fire that occurred chiliads _before Man was made_--those during his protracted _paradisaic state_, or those at the time _of the Flood_?--the extension of the Mosaic record _to universal nature_, or its limitation to a region of _south-western Asia_? I am not blaming, far less despising, the efforts that have been made for harmonizing the teachings of Scripture and science. I heartily sympathise with them. What else could good men do? They could not shut their eyes to the facts which Geology reveals: to have said they were not facts would have been simply absurd. Granting that the whole truth was before them--the whole evidence--they could not arrive at other conclusions than those just recorded; and, therefore, I do not blame their discrepancy _inter se_. _The true key has not as yet been applied to the wards._ Until it be, you may force the lock, but you cannot open it. Whether the key offered in the following pages will open the lock, remains to be seen. II. THE WITNESS FOR THE MACRO-CHRONOLOGY. "You shall well and truly try, and a true deliverance make,... and a true verdict give, according to the evidence."--(_Jury Oath._) A High Court of Inquiry has been sitting now for a good many years, whose object is to determine a chronological question of much interest. It is no less than the age of the globe on which we live. Counsel have been heard on both sides, and witnesses have been called, and most of the judges have considered that an overwhelming preponderance of testimony is in favour of an immeasurably vast antiquity. A single Witness on the other side, however, has deposed in a contrary sense: and, though he has said but little, some of those who have heard the cause attach such weight to his testimony, that they do not feel satisfied to let it be overborne. Counsel on the former side have, indeed, cross-examined the Witness, and dissected his testimony with much skill, and they contend that what he said has been misunderstood by the minority; and that, as his words may at least bear a sense which would not contradict those of the opposing witness, the clear, copious, and unvarying deposition previously made, ought to command the verdict of the Court. The minority are silenced, but not satisfied; they know not how to give up the Witness on whose veracity they have been wont to rely; but they are unable to answer the arguments brought against him. Counsel for the Brachy-chronology speaks. "We respectfully ask the Court for another hearing. Will our learned brother permit his witness briefly to recapitulate his testimony, and we will endeavour to examine it once more; for we think we shall be able to detect some flaw in it?" Rule granted. WITNESS FOR THE MACRO-CHRONOLOGY. The following, then, is the substance of what the witness deposes. He is not a living witness; his testimony, therefore, is not oral, but written--lithographed, in fact. It consists of a number of documents, which are couched in a language and character not to be understood without some previous study, but yet very capable of translation--very clear and unmistakeable. The following, I say, is a condensed summary of the leading points. If a curious person had watched the process of making the excavations that were preliminary to the boring of the Thames Tunnel, he would have observed that the labourers exposed successive layers of earth, differing much in colour, consistency, and general character. First, an accumulation of soil, consisting of decayed vegetable and animal matter, mingled with broken pottery, and other rubbish of man's production, was removed; then a layer of sand, gravel, and river mud; then a bed of reddish clay; then a layer of clay, mixed with silt or fine sandy mud; then a thin layer of silt, much filled with shells; then a stratum of stiff blue clay; then a layer of clay of more mottled character, containing a portion of silt, and some shells; then a stratum of very firm clay, so solid that it required to be broken with wedges; then a bed of gravel and sand of a green colour; and finally, a similar layer, but of a coarser texture. In the course of the hundred feet or so of perpendicular depth thus exposed, he would have seen a succession of layers, apparently deposited upon one another. But as yet he would have formed a very inadequate notion of the stratification of the earth's crust. With the knowledge thus gained, however, let him now make a little excursion into Hertfordshire; we will suppose at the time when the cuttings for the Great Northern Railway were being made. When he came near Cheshunt, he would see that the London clay, which he found underlying the Thames, crops out, or disappears by the stratum coming obliquely to the surface. He would see, however, another bed of clay--the plastic clay--beneath this, which now forms the superficial stratum, and continues to do so, till he gets beyond Hertford. There this stratum crops out; and the chalk, which for some time he has seen to underlie the plastic clay, now comes to the surface. Business or pleasure calls him to Bridlington on the Yorkshire coast; and he determines to make a pedestrian tour across the diameter of England to Whitehaven. He soon recognises the chalk, which constitutes the Wolds, and rises to about 800 feet above the sea level. Below its escarpment he traces the Kimmeridge clay, the uppermost of a series of strata more than 2,000 feet in thickness, that constitute the Oolitic system--including, among others, the coralline oolite, the calcareous grit, the cornbrash, thin, but rich in fossils; the lower sandstone and coal of the Cleveland hills, the alum shale, the marlstone, and the lower lias shale. Then comes a stratum of the saliferous system or the new red sandstone, with the red marls, perhaps not much short of a thousand feet deep. Below them the observer finds the strata of the magnesian limestone formation, for nearly 400 feet, resting on the great coal formations of vast depth. Of these the coal field of the West Riding is not less than 4,000 feet in depth, and beneath it lie the millstone grit, and the mountain limestone, 2,500 feet more, the latter displayed in noble grandeur on the faces of those wall-like precipices that inclose the romantic dales of the Swale and the Ure, and that subsequently tower in magnificent altitude on the sides of Pennygant and Ingleborough. [Illustration: GEOLOGICAL SECTION OF YORKSHIRE.] On the western escarpment of the Pennine ridge, just as the traveller is entering Westmoreland, he would detect the bottom of the limestone; and here he would have an opportunity of seeing, what is rare in these parts, a stratum of the old red sandstone, lying between the former and the slaty rocks of the Cumbrian formations. And here at length, in the wild and magnificent scenery of these mountains, he sees the primitive and transition series, the greenstone, the sienite, and the granite, each of which is discernible in succession on the face of one or other of the lofty Fells of Cumberland. Our traveller now comes home, and, musing on what he has seen, counts up some thirty or more distinct strata lying in regular succession one on another. But he has not seen all the world, nor even all England; but he reads the results of many independent observations, and finds that while, for the most part, the strata which he has seen are common to the whole surface of the globe, and while the order of their superposition is invariable everywhere, others are in some parts added, while perhaps some of those which he has observed are locally absent. Thus he is able to form a more distinct idea of the stratification of the earth's crust as a whole. It is composed of about forty distinct formations, generally increasing in thickness as we go downwards, so that the whole cannot be much less than ten miles in depth, supposing them in any locality to be all present, and to be lying in the horizontal plane. Mathematicians have satisfactorily determined that the mean density of the globe is about five-and-a-half times that of water, or about twice that of granite, a fact inconsistent with any other supposition than that the interior is occupied by substances maintained in a fluid state by intense heat. The lowest point that has yet been patent to human observation is occupied by the granite, a compound rock, which bears evident marks of having been once in a state of fusion, and of having cooled slowly, and that under immense pressure, contracting and crystallizing as it parted with its heat. There is every reason to believe that the granite is not defined at its inferior surface, but that it merges into the molten mass, probably still solidifying. After the outer portion of the granite had cooled sufficiently to become solid, there is evidence that it was covered by water, agitated by powerful currents, and probably in a heated state. The action of these currents disintegrated the rock, and deposited the constituent substances at the bottom of the sea--on the surface, and in the hollows, of the granite. For there is reason to think that the contraction of the primitive rock in the process of cooling, produced irregular undulations or crumplings of the surface, and frequent fractures and dislocations, elevating some parts and depressing others. The gneiss, the mica-schist, and the clay-slate, which are found immediately overlying the granitic rock in strata of vast thickness, are but the components of granite, separated and rearranged. "If we imagine common granite coarsely pounded, and thrown into a vessel of water, it will arrange itself at the bottom of the vessel in a condition very much like that of gneiss, which is indeed nothing else than stratified granite. If the water in which the pounded rock is thrown is moving along at a slow rate, and the clayey portion of the granite, called _felspar_, happens to be somewhat decomposed, as it often is, then the felspar (which is so truly _clay_ that it makes the best possible material for the use of the potteries) and the thin shining plates of mica, will be carried further by the water than the lumps of white quartz or flint sand, which, with the other two ingredients, made up the granite; and the two former will be deposited in layers, which, by passing a galvanic current through them, would in time become mica-schist. If the mica were absent, or if the clay were deposited without it, owing to any cause, then a similar galvanic current would turn the deposit into something like clay-slate."[25] The deposition of these strata, being formed out of granite, supposes the pre-existence of that rock; and as they occur in vast thicknesses, even of many thousand feet, then separation, deposition, and reconsolidation must have occupied, however rapidly we may suppose the processes to have been accomplished, considerable periods of time. In these lower rocks, no trace of organic remains has been found. The shoreless ocean that covered the cooling surface of the earth's crust, harboured no polype or sponge, no rhizopod or infusorium, and the angles and clefts of the granite were fringed by no fucus, or conferva: all was waste and void. And if certain parts were elevated above the waters, the bleak and barren points were not clothed with grass, or moss, or even a lichen, and no animal wandered over their ridges. Or, if such did exist, either in land or water, all vestiges of their presence have been destroyed by the agency of the intense heat that subsequently prevailed. But, in the numerous strata that overlie the rocks of granitic origin, there are found, in varying abundance, proofs that, when they were deposited, the surface of our earth had become the abode of organic life. Zoophytes lived in the ocean, some of which were engaged in secreting lime from the water, and depositing it in coral-reefs; stalked and jointed Star-fishes waved like lilies of stone from the submerged rocks; Sea-worms twined over the mud; mailed Crustaceans swam to and fro; and Mollusks, both bivalve and univalve, crawled over the ledges or reposed in the crevices. The remains of these occur in the Silurian rocks that lie immediately on the primitive granitic formations of Cumberland and North Wales. The construction of the coral-reefs of that deposit, in particular, must have occupied a lengthened period, continuing to go on, "month after month, year after year, century after century, until at length the depth changed, in which they could most conveniently live, or, owing to some other cause, their labours were brought to a close, and they disappeared from amongst existing species."[26] [Illustration: A TRILOBITE. (_Calymene Blumenbachii._) _a._ extended; back view. _b._ rolled up; side view. _c._ rolled up; front view.] Not a single species, or even a single genus of those early strata, is identical with any that exists now. The Coral-polypes, for instance, while allied to ours, are quite distinct from them, though endowed with similar powers and habits, so that we may reason from analogy on the laws of their deposits. The Trilobites were allied to the tiny water-fleas (_Entomostraca_) of the present day: like the _Oniscidæ_ (wood-lice, buttons, &c.) of our gardens, they had the habit of rolling their plated bodies into a ball. These are found in great numbers, their remains often heaped on one another. The Mollusca of those seas were chiefly of the class _Cephalopoda_--one of the least populous now-a-days, but then existing in vast number and variety; the Brachiopoda, Conchifera, and Gastropoda, were, however, well represented also. Such were the inhabitants of the sea during the Silurian period, in which a series of solid deposits were made, the aggregate, probably, exceeding 50,000 feet in thickness. Each deposit, though not more than a few inches in depth, "is provided with its own written story, its sacred memoranda, assuring us of the regularity and order that prevailed, and of the perfect uniformity of plan." Over all these, however, we see laid the strata of the Devonian system, especially the old red sandstone, which in some places attains a thickness of 10,000 feet. It is composed of a coarse agglomeration of broken fragments of the old granitic rocks, rolled and tossed about, apparently by the ever-breaking waves of shingle-beaches, until the hardest stones are worn into rounded pebbles by long and constant attrition. An examination of the old red sandstone, as is seen in Herefordshire, will aid us in forming a notion of the time required for its production. It is composed of fragments obtained by the disintegration of more ancient rocks, which, by a long process of rolling together in a breaking sea, or in the bed of a rapid current, have lost all their angles. The pebbles, thus worn, have at length settled,--the heaviest lowest,--and the whole has been consolidated into firm rock. "In many places," says Dr. Pye Smith, "the upper part of this vast formation is of a closer grain, showing that it was produced by the last and finest deposits of clayey and sandy mud, tinged, as the whole is, with oxides and carbonates of iron, usually red, but often of other hues. But, frequently, the lower portions, sometimes dispersed heaps, and, sometimes, the entire formation, consist of vast masses of conglomerate, the pebbles being composed of quartz, granite, or some other of the earliest kinds; and thus showing the previous rocks, from whose destruction they have been composed. Let any person first acquire a conception of the extent of this formation, and of its depth, often many hundreds, and, sometimes, two or three thousand feet; (but such a conception can scarcely be formed without actual inspection;) then let him attempt to follow out the processes which the clearest evidence of our senses shows to have taken place; and let him be reluctant and sceptical to the utmost that he can, he cannot avoid the impression that ages innumerable must have rolled over the world, in the making of this single formation."[27] Here, Fishes are added to the Invertebrate Animals. A sort of Shark with the mouth terminal, instead of beneath the head, was the earliest representative of this class. But closely following on this, were some curious species, enveloped in plate mail, and remarkable for the singularity of their forms, as the _Cephalaspis_ and the _Pterichthys_. [Illustration: CEPHALASPIS.] This great period passed away, and was succeeded by that of the Carboniferous deposits, indicative of a vast change in the physical character of the earth's surface and atmosphere. This change of character may be briefly summed up as consisting of an immense abundance of lime in the ocean, and of an equally vast charge of carbonic acid in the atmosphere. Strata of limestone, 2,500 feet in thickness, were accumulated in the ocean by the labours of Coral-polypes, allied to, but totally distinct from, those which had previously existed in the primary system. On the floor of a shallow sea, which then occupied the middle of what is now England, the coral reefs rose perpetually towards the day, atom by atom, the strata on which they were founded slowly and steadily sinking ever to a lower level, while successive generations of the industrious zoophytes wrought upwards, to maintain their position within reach of the light and warmth. What period of time was requisite for the aggregation of coral structure to the perpendicular thickness of 2,500 feet? While this was going on, other Invertebrata were living in the shallow seas, mostly differing from the older species, which had become by this time extinct. Encrinites and Sea-urchins existed; some _Foraminifera_ were astonishingly abundant; the _Cephalopoda_ and the _Brachiopoda_ presented a vast variety of species; and about seventy sorts of Fishes, mostly Sharks, characterised the age. On the coral limestone lies a sort of conglomerate, known as the millstone grit; and on this is laid that source of Britain's eminence, the _coal_. The coal measures of South Wales are estimated at 12,000 feet in thickness. The profusion of vegetable life that must have combined to make the coal in these, has no parallel in this age; no, not in the teeming forests of South America, or the great isles of the Oriental Archipelago. The circumstances which favoured this enormous development of plants, seem never to have been repeated in subsequent ages, since the coal measures which are found in the later strata are thin and inconsiderable, compared with those we are considering. M. Adolphe Brogniart suggests that in this period, from some source or other, carbonic acid was generated in vast abundance; or, at least, that it existed in the air, in a far greater proportion than it does now; and it is singularly confirmatory of his view, that terrestrial animals, to which this gas is fatal, have left almost no traces of their existence, during the age of these vast forests--a circumstance otherwise strange and unaccountable. "Those parts," says Mr. Ansted, "of the great carboniferous series which generally include the beds of coral, consist of muddy and sandy beds, alternating with one another, and with the coal itself. Some of them would appear to be of fresh-water, and some of marine origin; and they abound, for the most part, with remains of the leaves of Ferns and fern-like trees, together with the crushed trunks of these and other trees, whose substance may have contributed to form the great accumulations of bituminised and other vegetable carbon obtained from these strata. "It is not easy to communicate such an idea of beds of coal as shall enable the reader to understand clearly the nature of the circumstances under which they may have been deposited, and the time required for this purpose. The actual total thickness of the different beds in England varies considerably in different districts, but appears to amount, in the Lancashire coal-field, to as much as 150 feet. In North America there is a coal-field of vast extent, in which there appears at least as great a thickness of workable coal as in any part of England; while in Belgium and France the thickness is often much less considerable, although the beds thicken again still further to the east. "But this account of the thickness of the beds gives a very imperfect notion of the quantity of vegetable matter required to form them; and, on the other hand, the rate of increase of vegetables, and the quantity annually brought down by some great rivers, both of the eastern and western continents, is beyond all measure greater than is the case in our drier and colder climate. Certain kinds of trees which contributed largely to the formation of the coal, seem to have been almost entirely succulent, and capable of being squeezed into a small compass during partial decomposition. This squeezing process must have been conducted on a grand scale, both during and after the formation of separate beds; and each bed in succession was probably soon covered up by muddy and sandy accumulations, now alternating with the coal in the form of shale and grit-stone. Sometimes, trunks of trees caught in the mud would be retained in a slanting or nearly vertical position, while the sands were accumulating round them; sometimes the whole would be quietly buried, and soon cease to exhibit any external marks of vegetable origin.[28] "To relate the various steps in the formation of a bed of coal, and the gradual superposition of one bed upon another, by which at length the whole group of the coal-measures was completed, would involve an amount of detail little adapted to these pages; and when it is remembered that the woody fibres, after being deposited, had to be completely changed, and the whole character of the vegetable modified, before it could be reduced to the bituminous, brittle, almost crystalline mineral now dug out of the earth for fuel, it will rather seem questionable whether the origin of coal was certainly and necessarily vegetable, than reasonable to doubt the importance of the change that has taken place, and the existence of extraordinary means to produce that change. Nothing, however, is more certain than that all coal was once vegetable; for in most cases woody structure may be detected under the microscope; and this, if not in the coal in its ordinary state, at least in the burnt ashes which remain after it has been exposed to the action of heat, and has lost its bituminous and semi-crystalline character. This has been too well and too frequently proved by actual experiment, to require more than the mere statement of the fact."[29] An eminent practical geologist thus essays to guess the age of the coal-fields, and of the sandstone that underlies it. "The great tract of peat near Stirling has demanded [for its formation] two thousand years; for its registry is preserved by the Roman works below it. It is but a single bed of coal. Shall we multiply it by 100? We shall not exceed,--far from it,--did we allow 200,000 years for the production of the coal-series of Newcastle, with all its rocky strata. A Scottish lake does not shoal at the rate of half a foot in a century; and that country presents a vertical depth of far more than 3,000 feet in the single series of the oldest sandstone. No sound geologist will accuse a computer of exceeding, if he allow 600,000 years for the production of _this series alone_. And yet what are the coal deposits, and what the oldest sandstone, compared to the entire mass of the strata?"[30] The conjecture, that the whole of the vegetable material now constituting the coal, was the growth of the antediluvian centuries, and that it was floated away and deposited by the flood, is untenable. In not a few instances trunks are found broken, and worn by water-action; but the great mass warrants the conclusion that trees of vast dimensions and of close array--dense, majestic forests, such as now occur only in the most humid regions of the tropics--were submerged in their native abodes, lying where they fell, and where they have left the impressions, side by side, on the upper and under surfaces of the shale, of their delicate peculiarities of structure, which would have been totally obliterated, if the trees had been sea-borne and shore-rolled, as pretended. The result of a careful and minute examination of the phenomena of coal, by Mr. Binney, is, that the vegetable matter now forming coal had grown in vast _marine_ swamps, subjected to a series of _subsidences_ with long intervals of repose; that the trees, and perhaps smaller plants, were submerged under _tranquil_ water, in the places of their growth; and that very inconsiderable portions, if any, of the beds, are owing to drifting.[31] While the coal was in process of deposition, the sea was occupied with Invertebrata, not widely differing from those which had marked the previous eras. Fishes, however, were advancing in development; and several new and strange forms, some of them of gigantic dimensions and formidable armature, were introduced. These were chiefly remarkable for their affinities with Reptiles (whence they are often called _Sauroid_ Fishes); and one of them--_Megalichthys_--was famished with jaws of serried teeth, surpassing those of the crocodile. With these were associated other and more ordinary Fishes; and swarms of Sharks of many species, and varying much in size, roved through the sea, maintaining the same pirate character as their representatives of our modern seas--fierce, subtle, voracious, and powerful. At this time, too, appeared the earliest Reptiles, chiefly of the Amphibia sub-class. Some of these are known only by their foot-prints; and the late Hugh Miller has graphically described the appearance of some of these, which, he met with marking the roof of a coal-mine, four hundred feet below the surface. These must have been _Batrachia_ of large size, as the fore feet were thirteen inches apart across the breast.[32] They will be alluded to again. With these exceptions, remains of terrestrial animals are, as has already been observed, rare in this formation. III. THE WITNESS FOR THE MACRO-CHRONOLOGY. (CONTINUED.) "Always distrust very plain cases: beware lest a snake suddenly start out upon you, in the shape of some concealed and utterly unexpected difficulty."--WARREN: _Law Studies_. We have hitherto been considering the strata as if they had remained permanent when once deposited, subject to no change, save the successive superposition of other strata upon them. But this is very far from being true. Enormous displacements, upheavings, contortions, and fractures, are observed in the strata, which tell of mighty forces having been at work upon them after their formation. The explanation of these phenomena is due to the internal heat, which ever and anon seems to concentrate its action on some special point, seeking and finding vent for itself by some alteration in the already consolidated crust. Sometimes, the mode of action has been the transmission of undulations through the crust, producing earthquakes, cracking and forcing apart strata already petrified, and bending and variously contorting those that have but partially become solid. Sometimes, the fiery impulse is sufficiently concentrated to break through the superincumbent materials, forcing a passage for the molten and incandescent rock, which then flows forth from the surface, penetrates into the cracks and fissures of the fractured strata, and frequently spreads into the hollows and over the summits of the latest formations. It is owing to such causes as these, that we find the rocky layers so often inclined at various angles to the horizon, instead of being parallel to it, as they would be of course deposited; occasionally standing quite perpendicularly, and even to a small extent reversed. The outcropping of formations, the long lines of cliff running across a country in parallel series, ("crag and tail,") the dipping of strata from some central point or ridge, and the non-correspondence between the bottom of one stratum and the top of the underlying one,--are all phenomena of this sort of powerful action, which has been more or less energetic at all periods. After the deposit of the Old Red Sandstone, the internal fire appears to have enjoyed a lull of its energy, if not a complete cessation, until the Coal Measures were complete. Then the long tranquility was again broken, and concussions so extensive and violent ensued, that hardly a single square mile of country can anywhere be found which is not full of fractured and contorted strata, the record of subterranean movements, which mostly occurred between the Carboniferous and the Premian deposits. The effects of these convulsions were manifest in the changed relations of land and sea, existing continents and islands being dislocated, severed, and swallowed up, while others were elevated from the depths of the previous ocean. It was from the wave-worn materials thus obtained from pre-existing strata, that the New Red Sandstone was consolidated. It consists chiefly of sand and mud, with few organic remains; and the hiatus thus found, in animals and vegetables, seems to be almost a complete one between the organisms of the preceding and the succeeding periods. The most interesting traces of the earth's tenants during the New Red formation, consist of foot-tracks impressed by the progress of animals along the yielding mud between the ranges of high and low tide. They afford a remarkable example (not, I think, sufficiently dwelt on) of the extreme rapidity with which deposits were consolidated; since the tracks must have been made, and the material consolidated, during the few hours, _at most_, that intervened between the recess and the reflux of the tide; since, if the mud had not so soon become solid, the flow of the sea would have instantly obliterated such marks, as it does now on our shores. [Illustration: LABYRINTHODON PACHYGNATHUS.] The principal animal, whose foot-prints have been identified, was an enormous Frog (_Labyrinthodon_), as big as a hippopotamus, but apparently allied, in its serried teeth, and in the bony plates with which it was covered, to the Crocodiles, which were its associates. It is curious that marks in the same material have chronicled the serpentine trail of a Sea-worm, the scratchings of a Crab, the ripple of the wavelets, and even the drops of a passing shower; the last revealing, by their margins, the direction of the wind by which the slanting rain was driven. If the Triassic formations display but little evidence of organic existence, the lack is supplied by the abundance of such records, which is contained in the Oolitic system, and specially in its lowest component,--the Lias. Animals now existed in profusion, but of species which were for the most part peculiar. The coral-making Polypes existed not (or very rarely) in the seas of that age, but lime was secreted by an unusual number of Crinoid Echinoderms, which seem to have fringed the rocks and floating pieces of timber, much as Barnacles do now. Among the Mollusca now began to appear the inhabitants of those very elegant shells, the _Ammonites_, allied to the Nautilus of our Southern seas, which may be considered as the lingering representative of those swarms of shelled Cephalopoda. They were accompanied by their near relations, the _Belemnites_, more resembling a Cuttle, with a long internal, pointed shell. Fishes, chiefly belonging to a curiously armed tribe of Sharks, together with some enclosed in bony-mail like pavement, were present in the shallows, where the Lias was probably deposited. [Illustration: SNAKE-NECKED MARINE LIZARDS. _Plesiosaurus dolichodeirus_ and _P. macrocephalus_.] But the most characteristic animals were great marine Reptiles, of strange and uncouth forms, to which the present world presents us no known analogy. One of these was the _Ichthyosaurus_, which closely resembled a porpoise in form, but thirty or forty feet in length, with a vertical fish-like tail, and two pairs of paddles; a mouth set with stout crocodilian teeth, and enormous eyes. Another form was that of the _Plesiosaurus_, scarcely less in size than its fellow, which in the outline of its body it resembled: it was distinguished, however, by an extraordinary length of neck, slender and swan-like, consisting of thirty or forty vertebræ. It adds to the interest of these great marine Reptiles, that around their fossil skeletons are preserved pellets of excrement (known as Coprolites) containing fragments of bone, teeth, and scales of fishes, which clearly reveal the nature of their food. In some instances, the stomach and intestines of these great carnivorous creatures, filled with half-digested food, have left indubitable traces of their presence _in situ_. Again, the geography of the Globe changed. New lands arose from the sea, and old lands partially or wholly sank. The German Ocean, and part of Western Europe, of our maps, were a great group of islands. The Oolitic formation was deposited. The general character of the organization of this period differed little from that of the Lias. New forms of plants, such as _Cycadeæ_, were abundant, with, considerable numbers of Corals, Encrinites, Sea-urchins and Mollusks. Macrurous Crustacea, much like those of our times (but essentially different in species), inhabited the sea, and some Beetles and Flies represented the Insects of the land. The Fishes and Marine Reptiles were pretty much the same with those of the Lias, though they received some important additions. [Illustration: MEGALOSAURUS BUCKLANDI.] It is, however, among the terrestrial Vertebrata that we must look for the characteristic organisms of this age. And these are, still, Reptiles. The huge _Megalosaurus_, with a body as big as an elephant's, stood high on his legs, and stretched open a pair of gaping jaws, set with jagged teeth. The _Pterodactyles_ flew about,--carnivorous lizards, with the body and wings of bats,[33] except that the membrane was stretched upon the enormously developed little finger;--creatures, perhaps, the most unlike to anything familiar to us, of all fossil forms. And, in the marshy margins of the great river valley which formed the Wealden of our South-eastern districts, the giant _Iguanodon_, and his fellow, the _Hylæosaurus_, waged their peaceful warfare on the succulent plants that became their unresisting prey. [Illustration: BAT-LIZARDS. _Pterodactylus crassirostris_, and _P. brevirostris_.] [Illustration: HYLÆOSAURUS ARMATUS.] The circle of animal life was completed in this epoch, thus far, that every class was represented by some one or more of its constituent species. No fossil skeletons of Birds have, indeed, been found so low as the Oolite, but numerous foot-prints of some of the Grallatores are found in a sandstone of this period; and in the Stonesfield slate, which is contemporary with it, a genus of Mammalia has been discovered,--a small Marsupial, allied to the Opossums of America. The duration of the Oolitic period must have been considerable. "The lias sea-bottom was succeeded first by a sandy, and then by a calcareous deposit, and the animals were modified accordingly." The deposit of carbonate of lime, which took place under circumstances that caused it to attract around its nodules the organic particles, whence the name _oolite_ (egg-stone) is derived, was not continuous, but repeated at intervals. The shells of Mollusks were developed in great abundance, and accumulations of these formed thick bands, which consolidated into layers of shell-limestone. Three hundred feet of strata, largely composed of organic remains, were formed before the clay was deposited which made the Stonesfield and contemporaneous slates. Once more the dry land sank, probably by slow successive subsidences, and the sea flowed many fathoms deep above the great European archipelago. And upon its quiet bottom settled down, first a few sandy and clayey beds, and then the great layer of the Chalk. Creatures of very minute size and low grades of organization were now playing a very important part. A large portion of the lime that was deposited, in the form of a pure carbonate, was doubtless supplied by the Coral structures, which, were exceedingly numerous; the polypidoms being gnawed down by strong-jawed fishes that fed upon the Zoophytes. _Foraminifera_ also were abundant, and contributed to the supply. Nodules of flint exist in the Chalk, sometimes scattered, sometimes arranged in bands. Two sources are indicated for this substance. One is Sponge, the most common kinds of which are composed of skeletons of siliceous spicula; and these can be discerned with the microscope in the interior of the chalk-flints. But millions upon millions of Infusoria swam through the waters, and many of these were encased in siliceous loricæ, while the rocks and sea-weeds were fringed with as incalculably numerous examples of siliceous _Diatomaceæ_, whose elegant forms are recognisable without difficulty throughout the Chalk. The inconceivable abundance of these forms may be illustrated by the often-cited fact, that whole strata of solid rock appear to be so exclusively composed of their solid remains, that a cube of one-tenth of an inch is computed by Ehrenberg to contain five hundred millions of individuals. The increase of these organisms is very rapid, and their duration proportionately short; but allowing for this, what period would elapse before the successive generations of entities, of which forty-one thousand millions are required to make a cubic inch, would have accumulated into solid strata fourteen feet in thickness? Without pausing to examine the whole Cretaceous fauna, we may observe that the Mollusca with chambered shells--the Ammonites and their allies--were developed in singular variety and profusion during this period, after which they suddenly disappeared from the ocean. The Fishes present little that is remarkable; of Birds, few, and of Mammals, no remains exist; and the Reptiles, while not absolutely extinct, are few and rare. One great marine form, however, the _Mosasaurus_, was added to their number. At length the sea ceased to deposit chalk, and its bed appears to have been slowly elevated, until all the animals that had inhabited the waters of that formation were destroyed; so that their race and generation perished.[34] The grand epoch of Secondary Formations was closed. It was followed by an extensive disruption of the then existing strata, and by changes and modifications so great as to alter the whole face of nature. "It would appear that a long period of time elapsed before newer beds were thrown down, since the chalky mud not only had time to harden into chalk, but the surface of the chalk itself was much rubbed and worn." During this protracted period, eruptions of molten rock occurred of enormous extent, producing the Basaltic formation which covers the Chalk in the north of Ireland, and in some of the Hebrides. In the south of Europe the Pyrenees were elevated, and the Apennines and Carpathians were pushed to a greater altitude than before, if they were not then formed. The Alps and the Caucasus also experienced a series of upward movements, continuing through a considerable range of the Tertiary epoch. The rich collections of vegetable remains--chiefly fruits and seeds--that have been made from the London Clay, show that the earliest land of this period was clothed with a great abundance and variety of plants; and these are of such alliances as would now require a tropical climate. Many species of Palms, Screw-pines, Gourds, _Piperaceæ_, _Mimoseæ_, and other _Leguminosæ_, _Malvaceæ_, and _Coniferæ_, dropped their woody pods and fruits where now these pages are written; and the animals manifest no less interesting an approximation to existing forms than the plants. The Zoophytes, the Echinoderms, the Foraminifera, the Worms, the Crustacea, the Mollusca, the Fishes and the Reptiles of the Eocene beds, exhibit a great preponderance of agreement with those that now exist, _so far as genus is concerned_, though the _species_ are still almost wholly distinct. The approximation is particularly marked in the Molluscous sub-kingdom, by the almost entire disappearance of the hitherto swarming Brachiopod and Cephalopod forms, and the progressive substitution for them of the _Conchifera_ and _Gastropoda_, which had, however, throughout the Secondary epoch, been gradually coming forward to their present predominance in nature. Among the Fishes, the Placoid type was diminished in number; and those that were produced were mostly Sharks and Rays, of modern genera; but the chief difference was the paucity of those mailed forms (Ganoids), which were so abundant during the Oolitic period. On the other hand, the Ctenoid and Cycloid forms, which had begun to make their appearance in small numbers in the Chalk, are well represented. In both this deficiency and this plenitude, there is a very decided approach to existing conditions; for the Ganoids are almost unknown with us, while the last-named two orders are abundant. Representatives of our Perches, Maigres, Mackerels, Blennies, Herrings, and Cods, were numerous; _distinct, however, from the present species_. But not a single member of the great Salmon family was yet introduced. The great Saurian Reptiles had entirely disappeared, and were quite unrepresented in the tertiary beds, except by a Crocodile or two, and a small Lizard. Turtles were, however, numerous, both of the marine and lacustrine kinds; and there is an interesting stranger, in the form of a large Serpent, allied to our Pythons, some twenty feet in length. Birds and Mammals began now to assume their place on the land. The London Clay presents us with a little Vulture; and the Paris basin contains remnants of species representing the Raptores, the Rasores, the Grallatores, and the Natatores. The Quadrupeds came in in some force; not developed from the lowest to the highest scale of organization; for the Monkey and the Bat occur in sands, certainly not later, if not earlier, than the London Clay, contemporaneously with the Racoon, and before the existence of any Rodent or Cetacean. Some Carnivora, as the Wolf and the Fox, roamed the woods, but the character of the epoch was given by the Pachyderms. These, however, were not the massive colossi that browse in the African or Indian jungles of our days; no Elephant, no Rhinoceros, no Hippopotamus was as yet formed. But several kinds of Tapir wallowed in the morasses; and a goodly number of largish beasts, whose affinities were with the Pachydermata, while their analogies were with the Ruminantia, served as substitutes for the latter order, which was wholly wanting. These interesting quadrupeds, forming the genus _Anoplotherium_, were remarkable for two peculiarities,--their feet were two-toed, and their teeth were ranged in a continuous series, without any interval between the incisors and the molars. They varied in size from that of an ass to that of a hare. The physical conditions of our earth, when it was tenanted by these creatures, is thus described:--"All the great plains of Europe, and the districts through which the principal rivers now run, were then submerged; in all probability, the land chiefly extended in a westerly direction, far out into the Atlantic, possibly trending to the south, and connecting the western shores of England with the volcanic islands off the west coast of Africa. The great mountain chains of Europe, the Pyrenees, the Alps, the Apennines, the mountains of Greece, the mountains of Bohemia, and the Carpathians, existed then only as chains of islands in an open sea. Elevatory movements, having an east and west direction, had, however, already commenced, and were producing important results, laying bare the Wealden district in the south-east of England. The southern and central European district, and parts of western Asia, were the recipients of calcareous deposits (chiefly the skeletons of _Foraminifera_), forming the Apennine limestone; while numerous islands were gradually lifted above the sea, and fragments of disturbed and fractured rock were washed upon the neighbouring shallows or coast-lines, forming beds of gravel covering the Chalk. The beds of Nummulites and Miliolites, contemporaneous with those containing the Sheppey plants and the Paris quadrupeds, seem to indicate a deep sea at no great distance from shore, and render it probable that there were frequent alternations of elevation and depression, perhaps the result of disturbances acting in the direction already alluded to. "The shores of the islands and main land were, however, occasionally low and swampy, rivers bringing down mud in what is now the south-east of England, and the neighbourhood of Brussels, but depositing extensive calcareous beds near Paris. Deep inlets of the sea, estuaries, and the shifting mouths of a river, were also affected by numerous alterations of level not sufficient to destroy, but powerful enough to modify, the animal and vegetable species then existing; and these movements were continued for a long time."[35] After the elevation of the mountain summits of Europe above the sea, and while the same causes were still in operation, deposits were being made in the narrow intervening seas of the Archipelago, such as the present south of France, the valleys of the Rhine and Danube, the eastern districts of England and Portugal. These deposits were partly marine and partly lacustrine; the former consisting largely of loose sands, mingled with shells and gravel. In Switzerland is a thick mass of conglomerate; and in the district around Mayence, there is a series of fresh-water limestones, and sandstones charged with organic remains. The changes which took place during this comparatively recent epoch were not sudden, but gradual; the results of operations which were probably going on without intermission, and perhaps have not yet ceased. The land was more and more upheaved, till at length, what had been an archipelago of islands became a continent, and Europe assumed the form which it bears on our maps. The most interesting addition to the natural history of the Miocene, or Middle Tertiary period, was the _Dinotherium_--a huge Pachyderm, twice as large as an elephant, with a tapir-like proboscis, and two great tusks curving downward from the lower jaw. It was, doubtless, aquatic in its habits, and possibly (for its hinder parts are not known), it may have been allied to the Dugong and Manatee, those whale-like Pachyderms, with a broad horizontal tail, instead of posterior limbs. Other great herbivorous beasts roamed over the new-made land. The Mastodons, closely allied to the Elephant, had their head-quarters in North America, but extended also to Europe. And the Elephants themselves, of several species, were spread over the northern hemisphere, even to the polar regions. The Hippopotamus, the Rhinoceros, and other creatures, now exclusively tropical, were also inhabitants of the same northern latitudes. [Illustration: MAMMOTH.] From some specimens of Elephants and Rhinoceroses of this period, which seem to have been buried in avalanches, and thus to have been preserved from decomposition, even of the more transitory parts, as muscle and skin, we learn something of the climate that prevailed. The very fact of their preservation, by the antiseptic power of frost, shows that it was not a tropical climate in which they lived; and the clothing of thick wool, fur, and hair, which protected the skin of the Mammoth, or Siberian Elephant, tends to the same conclusion. At the same time, those regions were not so intensely cold as they are now. For the district in which the remains of Elephants and their associates are found, in almost incredible abundance, is that inhospitable coast of northern Asia which bounds the Polar Sea. The trees of a temperate climate--the oak, the beech, the maple, the poplar, and the birch--which now attain their highest limit somewhere about 70° of north latitude, and there are dwarfed to minute shrubs, appear then to have grown at the very verge of the polar basin; and that in the condition of vast and luxuriant forests, perhaps occupying sheltered valleys between mountains whose steep sides were covered with snow, already become perennial, and ever and anon rolling down in overwhelming avalanches, such as those which now occasionally descend into the valleys of the Swiss Alps. The coast of Suffolk displays a formation known as the Crag--a local name for gravel--which rests partly on the chalk; but, as it lies in other parts over the London Clay, it is assigned to the later Tertiary, or what is called the Pleiocene period. It is divided into the _coralline_ and the _red_ crag, the latter being uppermost where they exist together, and therefore being the more recent. The Coralline Crag is nearly composed of corals and shells, the former almost wholly extinct now; but the latter containing upwards of seventy species still existing in the adjacent seas. The Red Crag contains few zoophytes, but is remarkable for the remains of at least five species of Whales. Other Mammalia occur in this formation, among which are the red deer and the wild boar of modern Europe. The gradual but rapid approximation of the Tertiary fauna to that of the present surface is well indicated by Mr. Lyell's table (1841) of recent and fossil species in the English formations:-- Per-centage No. of Periods. Localities. of fossils recent. compared. Eocene {London and Hampshire } 1 or 2 400 Miocene {Red and Coralline } 20 to 30 450 { Crag, Suffolk } Older Pleiocene {Mamaliferous or Norwich } 60 to 70 111 { Crag } Newer Pleiocene {Marine strata near } 85 to 90 160 { Glasgow } Post Pleiocene {Fresh-water of the valley} 99 to 100 40 { of the Thames } It is to this period that are assigned the animals whose bones are found in astonishing numbers in limestone caverns, as, for example, that notable one at Kirkdale, in Yorkshire, which was examined by Professor Buckland. This is a cave in the Oolitic limestone, with a nearly level floor, which was covered with a deposit of mud, on which an irregular layer of sparry stalagmite had formed by the dripping of water from the low roof, carrying lime in solution. Beneath this crust the remains were found. Of the animals to which the bones belonged, six were _Carnivora_, viz. _hyæna_, _felis_, bear, wolf, fox, weasel; four _Pachydermata_, viz. elephant, rhinoceros, hippopotamus, horse; four _Ruminantia_, viz. ox, and three species of deer; four _Rodentia_, viz. hare, rabbit, water-rat, mouse; five Birds, viz. raven, pigeon, lark, duck, snipe. The bones were almost universally broken; the fragments exhibited no marks of rolling in the water, but a few were corroded; some were worn and polished on the convex surface; many indented, as by the canine teeth of carnivorous animals. In the cave the peculiar excrement of hyænas (_album græcum_) was common; the remains of these predacious beasts were the most abundant of all the bones; their teeth were found in every condition, from the milk-tooth to the old worn stump; and from the whole evidence Dr. Buckland adopted the conclusion, in which almost every subsequent writer has acquiesced, that Kirkdale Cave was a den of hyænas during the period when elephants and hippopotami (not of existing species) lived in the northern regions of the globe, and that they dragged into it for food the bodies of animals which frequented the vicinity.[36] Thus in these spots we find, observes Professor Ansted, "written in no obscure language, a portion of the early history of our island after it had acquired its present form, while it was clothed with vegetation, and when its plains and forests were peopled by many of the species which still exist there; but when there also dwelt upon it large carnivorous animals, prowling about the forests by night, and retiring by day to these natural dens." In our own country, and in many other parts of the world, we find fragments of stone distributed over the surface, sometimes in the form of enormous blocks, bearing in their fresh angles evidence that they have been little disturbed since their disruption, but sometimes much rubbed and worn, and broken into smaller pieces, till they form what is known as gravel. In many cases the original rock from which these masses have been separated does not exist in the vicinity of their locality; and it is not till we reach a distance, often of hundreds of miles, that we find the formation of which they are a component part. Various causes have been suggested for the transport of these erratic blocks, of which the most satisfactory is the agency of ice, either as slow-moving glaciers, or as oceanic icebergs. "The common form of a glacier," says Professor J. Forbes, "is a river of ice filling a valley, and pouring down its mass into other valleys yet lower. It is not a frozen ocean, but a frozen torrent. Its origin or fountain is in the ramifications of the higher valleys and gorges, which descend amongst the mountains perpetually snow-clad. But what gives to a glacier its most peculiar and characteristic feature is, that it does not belong exclusively or necessarily to the snowy region already mentioned. The snow disappears from its surface in summer as regularly as from that of the rocks which sustain its mass. It is the prolongation or outlet of the winter-world above; its gelid mass is protruded into the midst of warm and pine-clad slopes and green-sward, and sometimes reaches even to the borders of cultivation."[37] The glacier moves onward with a slow but steady march towards the mouth of its valley. Its lowest stratum carries with it numerous fragments of rock, which, pressed by the weight of the mighty mass, scratch and indent the surfaces over which they move, and sometimes polish them. These marks are seen on many rock-surfaces now exposed, and they are difficult to explain on any other hypothesis than that of glacial action. But the alternate influence of summer and winter--the percolation of rain into the mountain fissures, and the expansion of freezing--dislodge great angular fragments of rock, which fall on the glacier beneath. Slowly but surely these then ride away towards the mouth of the valley, till they reach a point where the warmth of the climate does not permit the ice to proceed; the blocks then are deposited as the mass melts. But if the climate itself were elevated, or if the surface were lowered so as to immerse the glacier in the sea, it would melt throughout its course, and then the blocks would be found arranged in long lines or _moraines_, such as we see now in many places. If the glacier-valley debouch on the sea, the ice gradually projects more and more, until the motions of the waves break off a great mass, which floats away, carrying on its surface the accumulation of boulders, gravel, and other _débris_ which it had acquired during its formation. It is now an iceberg, which, carried by the southern currents, approaches a warmer climate, melts, and deposits its cargo, perhaps hundreds of leagues from the valley where it was shipped, and as fresh as when its component _frusta_ were detached from the primitive rock. If the abundance of such erratic blocks and foreign gravel seem to require a greater amount of glacial action than is now extant, it has been suggested that the volcanic energy which elevated Europe may have been succeeded by a measure of subsidence before the land attained its present permanent condition. Hence there may have been, during the Tertiary epoch, mountain chains of great elevation, sufficient to supply the glaciers, which, on their subsidence, melted on the spot where they were submerged, or floated away as icebergs on the pelagic currents, till they grounded on the bays and inlets of other shores, which were subsequently elevated again. Thus a large portion of the animals which then inhabited these islands (up to that time, perhaps, united to the continent) would be drowned, and many species quite obliterated, a few alone remaining to connect our present fauna with that of the submerged area, when the land rose again to its existent state. It would not materially augment the force of the evidence already adduced on the question of chronology, to examine in detail the fossil remains of South America, Australia, and New Zealand. The gigantic Sloths[38] of the first, the gigantic Marsupials of the second, and the gigantic Birds of the third, however interesting individually, and especially as showing that a prevailing type governed the fauna in each locality then as now--are all formations of the Tertiary period, and some of them, at least, seem to have run on even into the present epoch. Indeed, it is not quite certain that the enormous birds of New Zealand and Madagascar are even yet extinct. The phenomenon of raised sea-beaches is one of great interest, and seems to be connected with the alternate elevations and depressions of the Tertiary epoch, perhaps marking the successive steps of the upheaval of the land. In several parts of England the coast-line exhibits one or more shelves parallel with the existing sea-beach, and covered with similar shingle, sand, and sea-shells. And the same phenomenon is exhibited on a still more gigantic scale in South America. Mr. Darwin[39] found that for a distance of at least 1,200 miles from the Rio de la Plata to the Straits of Magellan on the eastern side, and for a still longer distance on the west, the coast-line and the interior have been raised to a height of not less than 100 feet in the northern part, but as much as 400 feet in Patagonia. All this change has taken place within a comparatively short period; for in Valparaiso, where the effect is most considerable, modern marine deposits, with human remains, are seen at the height of 1,300 feet above the sea. At what exact point, geologically, the period of human history begins, it is impossible to say. No evidence of Man's presence has occurred older than the latest Tertiary deposits, which insensibly merge into the Alluvial. It seems certain that human remains have been found in chronological association with those of animals long extinct, and there appears no reason to doubt that some species of animals, as the Irish Deer, the Moa of New Zealand, and the Dodo of the Mauritius, have disappeared from creation within a period of a few centuries.[40] It is not improbable that the last of the Moho race may have lived only long enough to grace the pages of the "Birds of Australia." [Illustration: THE MOHO.] It is as important as it is interesting, to observe that the same kinds of physical operations have been, within the present epoch, and are still, going on, as those whose results are chronicled in the rocks. Strata of alluvium are constantly being formed on a scale which, though it does not _suddenly_ affect the outline of coasts, and therefore appears small, yet is great in reality. The Ganges is estimated to pour into the Indian Ocean nearly 6,400 millions of tons of mud every year; and its delta is a triangle whose sides are two hundred miles long. The delta of the Mississippi is of about the same size, and it advances steadily into the Gulf of Mexico at the rate of a mile in a century. The accumulation of river-mud is gradually filling up the Adriatic Sea. From the northernmost point of the Gulf of Trieste to the south of Ravenna, there is an uninterrupted series of recent accessions of land, more than a hundred miles in length, which, within the last twenty centuries, have increased from two to twenty miles in breadth. The coral-polypes are working still with great energy. Mr. Darwin mentions two or three examples of the rate of increase, one of which only I shall cite. In the lagoon of Keeling Atoll, a channel was dug for the passage of a schooner built upon the island, through the reef into the sea; in ten years afterward, when it was examined, it was found almost choked up with living coral. Volcanic action is busy in many parts of the earth, pouring forth clouds of ashes and torrents of molten rock; and instances are not wanting in which new islands have been raised from the bed of the ocean by this means, within the sphere of history. Slow and permanent changes of level are still being produced on the earth's crust. The bottom of the Baltic has been, for several centuries at least, in process of continuous elevation, the effects of which are palpable. Many rocks formerly covered are now permanently exposed; channels between islets, formerly used, are now closed up, and beds of marine shells have become bare. On the other hand, the whole area of the Pacific Polynesia seems subsiding. Deposits are being made by waters which hold earthy substances in solution. The principal of these is _lime_. Several remarkable examples of this kind are quoted by Sir Charles Lyell, in one of which there is a thickness of 200 or 300 feet of travertine of recent deposit, while in another a solid mass thirty feet thick was deposited in about twenty years. He also states that there are other countless places in Italy where the constant formation of limestone may be seen, while the same may be said of Auvergne and other volcanic districts. In the Azores, Iceland, and elsewhere, _silica_ is deposited often to a considerable extent. Deposits of _asphalt_ and other bituminous products occur in other places.[41] The floors of limestone caverns are frequently strewn with fossil bones, which are imbedded in stalagmite, and this incrustation is still in progress of formation. It is remarkable that in this deposit alone we obtain the bones of Man in a fossil condition. The two creations,--the extinct and the extant,--or rather the prochronic and the diachronic--here unite. But there is no line of demarcation between them; they merge insensibly into each other. The bones of Man, and even his implements and fragments of pottery, are found mingled with the skeletons of extinct animals in the caves of Devonshire, in those of Brazil,[42] and in those of Franconia. In Peru, some scores of human skeletons have been found in a bed of travertine, associated with marine shells; the stratum itself being covered by a deep layer of vegetable soil, forming the face of a hill crowned with large trees. From a very interesting paper by M. Marcel de Serres, it appears indubitable that the existing shells of the Mediterranean are even now passing in numbers into the fossil state, and that not in quiet spots only, but where the sea is subject to violent agitations. Specimens of common species, "completely petrified, have been converted into carbonate of lime at the same time that they have lost the animal matter which they originally contained. Their hardness and solidity are greater than those of some petrified species from tertiary formations." "In the collection of M. Doumet, Mayor of Cette, there exists an anchor which exhibits the same circumstances, and which is also covered with a layer of solid calcareous matter. This contains specimens of _Pecten_, _Cardium_, and _Ostrea_, completely petrified, and the hardness of which is equal to that of fossil species from secondary formations. On the surface of the deposit in which the anchor is imbedded, there are _Anomiæ_ and _Serpulæ_, which were living when the anchor was got out of the sea; these present no trace of alteration."[43] Thus we have brought down the record to an era embraced by human history, and even to individual experience; and we confidently ask, Is it possible, is it imaginable, that the whole of the phenomena which occur below the diluvial deposits can have been produced within six days, or seventeen centuries? Let us recapitulate the principal facts. 1. The crust of the earth is composed of many layers, placed one on another in regular order. All of these are solid, and most are of great density and hardness. Most of them are of vast thickness, the aggregate not being less than from seven to ten miles. 2. The earlier of these were made and consolidated before the newer were formed; for in several cases, it is demonstrable that the latter were made out of the _débris_ of the former. Thus the compact and hard granite was disintegrated grain by grain; the component granules were rolled awhile in the sea till their angles were rubbed down; they were slowly deposited, and then consolidated in layers. 3. A similar process goes on again and again to form other strata, all occupying long time, and all presupposing the earlier ones.[44] 4. After some strata have been formed and solidified, convulsions force them upward, contort them, break them, split them asunder. Melted matter is driven through the outlets, fills the veins, spreads over the surface, settles into the hollows, cools and solidifies. 5. After the outflowing and consolidation of these volcanic streams, the action of running water cuts them down, cleaving beds of immense depth through their substance. Mr. Poulett Scrope, speaking of the solidified streams of basalt, in the volcanic district of Southern France, observes:-- "These ancient currents have since been corroded by rivers, which have worn through a mass of 150 feet in height, and formed a channel even in the granite rocks beneath, since the lava first flowed into the valley. In another spot, a bed of basalt, 160 feet high, has been cut through by a mountain stream. The vast excavations effected by the erosive power of currents along the valleys which feed the Ardèche, since their invasion by lava-currents, prove that even the most recent of these volcanic eruptions belong to an era incalculably remote."[45] 6. A series of organic beings appears, lives, generates, dies; lives, generates, dies; for thousands and thousands of successive generations. Tiny polypes gradually build up gigantic masses of coral,--mountains and reefs--microscopic foraminifera accumulate strata of calcareous sand; still more minute infusoria--forty millions to the inch--make slates, many yards thick, of their shells alone. 7. The species at length die out--a process which we have no data to measure,[46] though we may reasonably conclude it very long. Sometimes the whole existing fauna seems to have come to a sudden violent end; at others, the species die out one by one. In the former case suddenly, in the latter progressively, new creatures supply the place of the old. Not only do species change; the very genera change, and change again. Forms of beings, strange beings, beings of uncouth shape, of mighty ferocity and power, of gigantic dimensions, come in, run their specific race, propagate their kinds generation after generation,--and at length die out and disappear; to be replaced by other species, each approaching nearer and nearer to familiar forms. 8. Though these early creatures were unparalleled by anything existing now, yet they were animals of like structure and economy essentially. We can determine their analogies and affinities; appoint them their proper places in the orderly plan of nature, and show how beautifully they fill hiatuses therein. They had shells, crusts, plates, bones, horns, teeth, exactly corresponding in structure and function to those of recent animals. In some cases we find the young with its milk-teeth by the side of its dam with well-worn grinders. The fossil excrement is seen not only dropped, but even in the alimentary canal. Bones bear the marks of gnawing teeth that dragged them and cracked them, and fed upon them. The foot-prints of birds and frogs, of crabs and worms, are imprinted in the soil, like the faithful impression of a seal.[47] 9. Millions of forest-trees sprang up, towered to heaven, and fell, to be crushed into the coal strata which make our winter fires. Hundreds of feet measure the thickness of what were once succulent plants, but pressed together like paper-pulp, and consolidated under a weight absolutely immensurable. Yet there remain the scales of their stems, the elegant reticulated patterns of their bark, the delicate tracery of their leaf-nerves, indelibly depicted by an unpatented process of "nature-printing." And when we examine the record,--the forms of the leaves, the structure of the tissues, we get the same result as before, that the plants belonged to a flora which had no species in common with that which adorns the modern earth. Very gradually, and only after many successions, not of individual generations, but of the cycles of species, genera, and even families, did the vegetable creation conform itself to ours.[48] 10. At length the species both of plants and animals grew,--not by alteration of their specific characters, but by replacement of species by species--more and more like what we have now on the earth, and finally merged into our present flora and fauna, about the time when we find the first geological traces of MAN. 11. During the course of these successive cycles of organic life, the map of the world has changed many times. Up to a late period the ocean washed over Mont Blanc and Mount Ararat; the continent of Europe was a wide sea; then it was a Polynesia, then an Archipelago of great islands, then a Continent much larger than it is now, with England united to it, and the solid land stretching far away into the Atlantic;--then it sank again, and was again raised, not all at once, but by several stages, each of which has left its coast line, and its shingle beach. All these changes must have been the work of vast periods of time. "Excepting possibly, but not certainly, the higher parts of some mountains, which at widely different epochs have been upheaved, and made to elevate and pierce the stratified masses which once lay over them, there is scarcely a spot on the earth's surface which has not been many times in succession the bottom of the sea, and a portion of dry land. In the majority of cases, it is shown, by physical evidences of the most decisive kind, that each of those successive conditions was of extremely long duration; a duration which it would be presumptuous to put into any estimate of years or centuries; for any alteration, of which vestiges occur in the zoological state and the mineral constitution of the earth's present surface, furnishes no analogy (with regard to the nature and continuance of causes), that approaches in greatness of character to those changes whose evidences are discernible in almost any two continuous strata. It is an inevitable inference, unless we are disposed to abandon the principles of fair reasoning, that each one of such changes in organic life did not take place till after the next preceding condition of the earth had continued through a duration, compared with which six thousand years appear an inconsiderable fraction of time."[49] 12. The climate of our atmosphere has undergone corresponding mutations. At one time the Palms, the Treeferns, the Cycads of the tropical jungles found their congenial home here: the Elephant, the Rhinoceros, and the Tiger roamed over England; nay, dwelt in countless hosts on the northern shores of Siberia: then the climate gradually cooled to a temperate condition: then it became cold, and glaciers and icebergs were its characteristic features: finally it became temperate again. 13. The icebergs and the glaciers were the ships and railways of past epochs; they were freighted with their heavy but worthless cargoes of rock-boulders and gravel, and set out on their long voyages and travels, over sea and land, sometimes writing their log-books in ineffaceable scratches on the rocky tables over which they passed, and at length discharging their freights in harbours and bays, on inland plains, on mountain sides and summits, where they remain unclaimed, free for any trader in such commodities, without the ceremony of producing the original bill of lading. Let the remainder be told in the words of one of our most eloquent and able geologists, Professor Sedgwick. "The fossils demonstrate the time to have been _long_, though we cannot say _how_ long. Thus we have generation after generation of shell-fish, that have lived and died on the spots where we find them; very often _demonstrating_ the lapse of _many years_ for a few perpendicular inches of deposit. In some beds we have large, cold-blooded reptiles, creatures of long life. In others, we have traces of ancient forests, and enormous fossil trees, with concentric rings of structure, marking the years of growth. Phenomena of this kind are repeated again and again; so that we have three or four distinct systems of deposit, each formed at a distinct period of time, and each, characterised by its peculiar fossils. Coeval with the Tertiary masses, we have enormous lacustrine deposits; sometimes made up of very fine thin laminæ, marking slow tranquil deposits. Among these laminæ, we can find sometimes the leaf-sheddings and the insects of successive seasons. Among them also we find almost mountain-masses of the _Indusioe tubulatoe_ [the cases of _Phryganeoe_], and other sheddings of insects, year after year. Again, streams of ancient lava alternate with some of these lacustrine tertiary deposits. "In central France, a great stream of lava caps the lacustrine limestone. At a _subsequent period_ the waters have excavated deep valleys, cutting down into the lacustrine rock-marble many hundred feet; and, at a newer epoch, anterior to the authentic history of Europe, new craters have opened, and fresh streams of lava have run down the existing valleys. Even in the Tertiary period we have thus a series of demonstrative proofs of a long succession of physical events, each of which required a long lapse of ages for its elaboration. "Again, as we pass downwards from the bottom Tertiary beds to the Chalk, we instantly find new types of organic life. The old species, which exist in millions of individuals in the upper beds, disappear, and new species are found in the chalk immediately below. This fact indicates a long lapse of time. Had the chalk and upper beds been formed simultaneously at the same period [as the supporters of the diluvial theory represent], their organic remains must have been more or less mixed; but _they are not_. Again, at the base of the Tertiary deposits resting on the Chalk, we often find great masses of conglomerate or shingle, made up of chalk-flints rolled by water. These separate the Chalk from the overlying beds, and many of the rolled flints contain certain petrified _chalk_-fossils. Now, every such fossil proves the following points:-- "1. There was a time when the organic body was alive at the bottom of the sea. "2. It was afterwards imbedded in the cretaceous deposit. "3. It became petrified; a very slow process. "4. The Chalk was, by some change of marine currents, washed away, or degraded, [_i. e._ worn away under the atmosphere by the weather and casualties, a process slow almost beyond description,] and the solid flints and fossils [thus detached from their imbeddings], were rolled into shingles. "5. Afterwards, these shingles were covered up, and buried under Tertiary deposits. "In this way of interpretation, a section of _a few perpendicular feet_ indicates a LONG lapse of time, and the co-ordinate fact of the entire change of organic types, between the beds above and those below, falls in with the preceding inference, and shows the lapse of time to have been VERY LONG."[50] IV. THE CROSS-EXAMINATION. "When the fact itself cannot be proved, that which comes nearest to the proof of the fact is the proof of the circumstances that necessarily and usually attend such facts; and _these are called presumptions, and not proofs_, for they stand instead of the proofs of the fact, till the contrary be proved."--GILBERT; LAW OF EVIDENCE. Such, then, is the evidence for the macro-chronology. I hope I have summed it up fairly; of course, many details I have been forbidden to adduce by want of space, but they would have been of the same kind as those brought forward. I am not conscious of having in any degree cushioned, or concealed, or understated a single proof which would have helped the conclusion. A mighty array of evidence it certainly is, and such as appears at first sight to compel our assent to the sequent claimed for it. I must confess that I have no sympathy with the _reasonings_ of those, however I honour their design, who can find a sufficient cause for these phenomena in the natural operations of the Antediluvian centuries, or in the convulsion that closed them. But is there no other alternative? Am I compelled to accept the conclusions drawn from the phenomena thus witnessed unto, as undeniable facts, since they refuse to be normally circumscribed within the limits of the historic period? I verily believe there is another, and a perfectly legitimate solution. My first business is to examine, and, if I can, to disprove this testimony. If I can show the witness to be liable to error; if I can adduce a principle which invalidates all his proofs; if I can make it undeniably manifest that, in a case precisely parallel, similar conclusions, deduced from exactly analogous phenomena, would be notoriously false; if I can do this, I think I have a right to demand that the witness be bowed out of court, as perfectly nugatory and worthless _in this cause_. In the first place, there is nothing here but _circumstantial_ evidence; there is no _direct_ testimony to the facts sought to be established. Let it not seem unfair to make this distinction; it is one of great importance. No witness has deposed to actual observation of the processes above enumerated; no one has appeared in court who declares he actually saw the living _Pterodactyle_ flying about, or heard the winds sighing in the tops of the _Lepidodendra_. You will say, "It is the same thing; we have seen the skeleton of the one, and the crushed trunk of the other, and therefore we are as sure of their past existence as if we had been there at the time." No, it is not the same thing; it is not _quite_ the same thing; NOT QUITE. Strong as is the evidence, it is not _quite_ so strong as if you had actually seen the living things, and had been conscious of the passing of time while you saw them live. It is only by a process of reasoning that you infer they lived at all.[51] The process is something like this. Here is an object in a mass of stone, which has a definite form,--the form of the bone of a beast. The more minutely you examine it, the more points of resemblance you find; you say, If this is a bone, it ought to have so and so--condyles, scars for the attachment of muscles in particular spots, a cavity for the reception of marrow, a mark for the insertion of the ligament; you look for each of these, and find all in the very conditions you have prescribed; it is not only a bone, but a particular bone, the thigh-bone, for instance. Here in the same block of stone is another object: you work it out; it is another bone; its joint accurately fits the preceding; it answers precisely to the tibia of a mammal. Other bones at length appear, and you have got a perfect skeleton, no part redundant, none wanting; the most minute, the most elaborate, the most delicate portions of the osseous frame of a mammal are present, and every one exactly correspondent to the rest in size, in maturity, _in fit._ Each bone, out of the scores, displays exactly those characters, and no other, which an anatomist would have said beforehand it ought to have. Allowing for the difference of species, the skeleton, when worked out of its matrix, and set up, is precisely like that of the little beast at whose death you were actually present, whose bones you cleaned with your own hands, and mounted for your own museum. It would be as reasonable to deny that the one is the skeleton of a real animal as the other. Thus far there is matter of fact--observed, witnessed fact; you have found in a stone a real skeleton. You immediately infer that this skeleton once belonged to a living animal, that breathed, and fed, and walked about, exactly as animals do now. This conclusion seems so obvious and unavoidable, that we naturally conclude it to rest on the same foundation as the fact that the object _is_ a skeleton, or that _it was_ in the stone. But really it rests on a totally different foundation; it is a conclusion deduced by a process of reasoning from certain assumed premises. Myriads, perhaps millions of skeletons of animals like this one have come at different times under human observation, which have been obviously referrible to creatures that, within the same sphere of observation, had been alive. No similar skeleton has ever come within the range of recorded observation that could be referred to any other source than that of a quondam living animal. On these premises you build the conclusion that a skeleton must, at some time or other, have belonged to a living animal. And it may seem an impregnable position; but yet its validity altogether depends on the exhaustive power of human observation. If I could show, to your satisfaction, that a skeleton might have existed; still more, if I could show you that a skeleton _must_ have existed; still more, if I could prove that myriads of skeletons, precisely like this, must have existed, without ever having formed parts of antecedent living bodies; you would yourself acknowledge that your conclusions were untenable. The utmost you could affirm, would be, that possibly, perhaps probably, the skeleton you had found in the stone had at some time belonged to a living animal, but that, so far as any recognised premises exist, there was no certainty about it. But the premises have not been fairly stated. There is more than the relation of precedence and sequence in what we know of the connexion between skeletons and living animals; there is the relation of cause and effect. It is not only that universal experience has declared the _fact_ that every skeleton was once part of a living body; it has shown that the very structure and nature of the skeleton _implied_ living body. The skeleton, in every part, displays a regard for the advantages of the living animal; it is built expressly for it; by itself it is nothing--a machine without any object; its joints, its cavities, its apophyses, its processes, all have special reference to tissues and organs which are not here now, but which belong to the living body. And then experience has shown that the skeleton is made in a particular manner. The bone is deposited, atom by atom, in living organic cells, which are formed by living blood, which implies a living animal. The microscopic texture of your stone-girt skeleton does not differ from that of the skeleton which you cleaned from the muscles with your own hands; and therefore you infer that it was constructed in the same way, namely, by the blood of a living body. Well, I come back, notwithstanding, to my position,--that your right to _affirm_ this must altogether depend on the exhaustive power of that experience on which you build. And it will be overthrown, if I can show that skeletons have been made in some other way than by the agency of living blood. Can I do this? I think I can. At least I think I can show enough greatly to diminish, if not altogether to destroy, the confidence with which you inferred the existence of vast periods of past time from geological phenomena. I can adduce a principle, having the universality (within its proper sphere) of LAW, hitherto unrecognised, whose tendency is to invalidate the testimony of your witness. V. POSTULATES. "A little philosophy inclineth a man's mind to atheism; but depth in philosophy bringeth men's minds about to religion; for while the mind of man looketh upon second causes scattered, it may sometimes rest in them, and go no farther; but when it beholdeth the chain of them confederate and linked together, it must needs fly to Providence and Deity."--BACON. "'What was the opinion of Pythagoras concerning wildfowl?' 'That the soul of our grand-dam might haply inhabit a bird.' 'What thinkest thou of his opinion?' 'I think nobly of the soul, and in nowise receive his opinion.'" SHAKSPEARE. As without some common ground it is impossible to reason, I shall take for granted the two following principles:-- I. THE CREATION OF MATTER. II. THE PERSISTENCE OF SPECIES. I. If any geologist take the position of the necessary eternity of matter, dispensing with a Creator, on the old ground, _ex nihilo nihil fit_,--I do not argue with him. I assume that at some period or other in past eternity there existed nothing but the Eternal God, and that He called the universe into being out of nothing. II. I demand also, in opposition to the development hypothesis, the perpetuity of specific characters, from the moment when the respective creatures were called into being, till they cease to be. I assume that each organism which the Creator educed was stamped with an indelible specific character, which made it what it was, and distinguished it from everything else, however near or like. I assume that such character has been, and is, indelible and immutable; that the characters which distinguish species from species _now_, were as definite at the first instant of their creation as now, and are as distinct now as they were then. If any choose to maintain, as many do, that species were gradually brought to their present maturity from humbler forms,--whether by the force of appetency in individuals, or by progressive development in generations--he is welcome to his hypothesis, but I have nothing to do with it. These pages will not touch him. I believe, however, there is a large preponderance of the men of science,[52] at least in this country, who will be at one with me here. They acknowledge the almighty _fiat_ of God, as the energy which produced being; and they maintain that the specific character which He then stamped on his organic creation remains unchangeable. VI. LAWS. "----[Greek: ton trochon tês geneseôs]."--JAMES iii. 6. The course of nature is a circle. I do not mean the _plan_ of nature; I am not speaking of a circular arrangement of species, genera, families, and classes, as maintained by MacLeay, Swainson, and others. Their theories may be true, or they may be false; I decide nothing concerning them; I am not alluding to any _plan_ of nature, but to its _course_, _cursus_,--the way in which it _runs on_. This is a circle. Here is in my garden a scarlet runner. It is a slender twining stem some three feet long, beset with leaves, with a growing bud at one end, and with the other inserted in the earth. What was it a month ago? A tiny shoot protruding from between two thick fleshy leaves scarcely raised above the ground. A month before that? The thick fleshy leaves were two oval cotyledons, closely appressed face to face, with the minute plumule between them, the whole enclosed in an unbroken, tightly-fitting, spotted, leathery coat. It was a bean, a seed. [Illustration: GERMINATION OF A SCARLET RUNNER. _a._ The ripe bean, showing the hilum at *; _b._ The same bean, with one cotyledon removed, to show the plumule. _c._ A similar bean, twenty-four hours after planting. _d._ The same, on the sixth day after planting. _e._ The same, on the twelfth day. _f._ The same, on the fourteenth day. N.B. From _b_, _c_, _d_, _e_, the front cotyledon has been cut away, to show the progress of the plumule.] Was this the commencement of its existence? O no! Six months earlier still it was snugly lying, with several others like itself, in a green fleshy pod, to the interior of which it was organically attached. A month before that, this same pod with its contents was the centre of a scarlet butterfly-like flower, the bottom of its pistil, within which, if you had split it open, you would have discerned the tiny beans, whose history we are tracing backwards, each imbedded in the soft green tissue, but no bigger than the eye of a cambric needle. But where was this flower? It was one of many that glowed on my garden wall all through last summer; each cluster springing as a bud from a slender twining stem, which was the exact counterpart of that with which we commenced this little life-history. And this earlier stem,--what of it? It too had been a shoot, a pair of cotyledons with a plumule, a seed, an integral part of a carpel, which was a part of an earlier flower, that expanded from an earlier bud, that grew out of an earlier stem, that had been a still earlier seed, that had been--and backward, _ad infinitum_, for aught that I can perceive. The course, then, of a scarlet runner is a circle, without beginning or end:--that is, I mean, without a natural, a normal beginning or end. For at what point of its history can you put your finger, and say, "Here is the commencement of this organism, before which there is a blank; here it began to exist?" There is no such point; no stage which does not look back to a previous stage, on which _this_ stage is inevitably and absolutely dependent. To some of my readers this may be rendered more clear by the accompanying diagram:---- [Illustration: legume--reed--cotyledons--shoot--stem--bud--flower--carpel] [Illustration: theca--spore--prothallus--sporal frond--tuft--caudex--fertile frond--sorus] See that magnificent tuft of Lady-fern on yonder bank, arching its exquisitely cut fronds so elegantly on every side. A few years ago this ample crown was but a single small frond, which you would probably not have recognised as that of a Lady-fern. Somewhat earlier than this, the plant was a minute flat green expansion (_prothallus_), of no definite outline, very much like a Liverwort. This had been previously a three-sided spore lying on the damp earth, whither it had been jerked by the rupture of a capsule (_theca_). For this spore, though so small as to be visible only by microscopic aid, had a previous history, which may be traced without difficulty. It was generated with hundreds more, in one of many capsules, which, were crowded together, beneath the oval bit of membrane, that covered one of the brown spots (_sori_), which were developed in the under surface of the fronds of an earlier Lady-fern. That earlier individual had in turn passed through the same stages of sporal frond, prothallus, spore, theca, sorus, frond, prothallus, spore, theca, sorus, frond, prothallus, &c.--_ad infinitum_. This sounding-winged Hawkmoth, which like a gigantic bee is buzzing around the jasmine in the deepening twilight, hovering ever and anon to probe the starry flowers that make the evening air almost palpable with fragrance,--this moth, what "story of a life" can he tell? Nearly a year of existence he has spent as a helpless, almost motionless pupa, buried in the soft earth, from whence he has emerged but this evening. About a twelvemonth ago he was a great fat green caterpillar with an arching horn over his rump, working ever harder and harder at devouring poplar leaves, and growing ever fatter and fatter. But before that he had one day burst forth a little wriggling worm, from a globular egg glued to a leaf. Whence came the egg? It was developed within the ovary of a parent Hawkmoth, whose history is but an endless rotation of the same stages,--pupa, larva, egg, moth, pupa, larva, &c. &c. [Illustration: larva--pupa--moth--egg] Behold this specimen of _Plumularia_, a shrub-like zoophyte, comprising within its populous branches some twenty thousand polypes. Every individual cell, now inhabited by its tentacled Hydra, has in its turn budded out from a branch, which was itself but a lateral process from the central axis. And this was but the prolongation of what was at first a single cell, shooting up from a creeping root-thread. A little earlier than this, there was neither cell nor root-thread, but the organism existed in the form of a _planule_, a minute soft-bodied, pear-shaped worm, covered with cilia, that crawled slowly over the stones and sea-weeds. Whence came it? A few hours before, it had emerged from the mouth of a vase-like cell, one of the ovarian capsules, which studded the stem of an old well-peopled Plumularia-shrub, and which had been gradually developed from its substance by a process analogous to budding. And then if we follow the history of this earlier shrub backward, it will only lead us through exactly correspondent stages, primal cell, planule, ovarian capsule, stem, and so on interminably. [Illustration: primal cell--axis--branch--polype--capsule--planule] Once more. The cow that peacefully ruminates under the grateful shadow of yonder spreading beech, was, a year or two ago, a gamesome heifer with budding horns. The year before, she was a bleating calf, which again had been a breathless foetus wrapped up in the womb of its mother. Earlier still it had been an unformed embryo; and yet earlier, an embryonic vesicle, a microscopically minute cell, formed out of one of the component cells of a still earlier structure,--the germinal vesicle of a fecundated ovum. But this ovum, which is the remotest point to which we can trace the history of our cow as an individual, was, before it assumed a distinct individuality, an undistinguishable constituent of a viscus,--the ovary,--of another cow, an essential part of _her_ structure, a portion of the tissues of _her_ body, to be traced back, therefore, through all the stages which I have enumerated above, to the tissues of another parent cow, thence to those of a former, and so on, through a vista of receding cows, as long as you choose to follow it. [Illustration: embryo--foetus--calf--heifer--cow--ovum--germ. vesicle--embr. vesicle] This, then, is the order of all organic nature. When once we are in any portion of the course, we find ourselves running in a circular groove, as endless as the course of a blind horse in a mill. It is evident that there is no one point in the history of any single creature, which is a legitimate beginning of existence. And this is not the law of some particular species, but of all: it pervades all classes of animals, all classes of plants, from the queenly palm down to the protococcus, from the monad up to man: the life of every organic being is whirling in a ceaseless circle, to which one knows not how to assign any commencement,--I will not say any certain or even probable, but any _possible_, commencement. The cow is as inevitable a sequence of the embryo, as the embryo is of the cow. Looking only at nature, or looking at it only with the lights of experience and reason, I see not how it is possible to avoid one of these two theories, the development of all organic existence out of gaseous elements, or the eternity of matter in its present forms. Creation, however, solves the dilemma. I have, in my postulates, begged the fact of creation, and I shall not, therefore, attempt to prove it. Creation, the sovereign fiat of Almighty Power, gives us the commencing point, which we in vain seek in nature. But what is creation? It is _the sudden bursting into a circle_. Since there is no one stage in the course of existence, which, more than any other affords a natural commencing point, whatever stage is selected by the arbitrary will of God, must be an unnatural, or rather a preter-natural, commencing point. The life-history of every organism commenced at some point or other of its circular course. It was created, called into being, in some definite stage. Possibly, various creatures differed in this respect; perhaps some began existence in one stage of development, some in another; but every separate organism had a distinct point at which it began to live. Before that point there was nothing; this particular organism had till then no existence; its history presents an absolute blank; _it was not_. But the whole organisation of the creature thus newly called into existence, looks back to the course of an endless circle in the past. Its whole structure displays a series of developments, which as distinctly witness to former conditions as do those which are presented in the cow, the butterfly, and the fern, of the present day. But what former conditions? The conditions thus witnessed unto, as being necessarily implied in the present organisation, were non-existent; the history was a perfect blank till the moment of creation. The past conditions or stages of existence in question, can indeed be as triumphantly inferred by legitimate deduction from the present, as can those of our cow or butterfly; they rest on the very same evidences; they are identically the same in every respect, except in this one, that they were _unreal_. They exist only in their results; they are effects which never had causes. Perhaps it may help to clear my argument if I divide the past developments of organic life, which are necessarily, or at least legitimately, inferrible from present phenomena, into two categories, separated by the violent act of creation. Those unreal developments whose apparent results are seen in the organism at the moment of its creation, I will call _prochronic_, because time was not an element in them; while those which have subsisted since creation, and which have had actual existence, I will distinguish as _diachronic_, as occurring during time. Now, again I repeat, there is no imaginable difference to sense between the prochronic and the diachronic development. Every argument by which the physiologist can prove to demonstration that yonder cow was once a foetus in the uterus of its dam, will apply with exactly the same power to show that the newly created cow was an embryo, some years before its creation. Look again at the diagram by which I have represented the life-history of this animal. The only mode in which it can begin is by a sudden sovereign act of power, an irruption into the circle. You may choose _where_ the irruption shall occur; there must be a bursting-in at some point. Suppose it is at "calf;" or suppose it is at "embr. vesicle." Put a wafer at the point you choose, say the latter. This then is the real, actual commencement of a circle, to be henceforth ceaseless. But the embryonic vesicle necessarily implies a germinal vesicle, and this necessitates an ovum, and the ovum necessitates an ovary, and the ovary necessitates an entire animal,--and thus we have got a quarter round the circle in back development; we are irresistibly carried along the prochronic stages,--the stages of existence which were before existence commenced,--as if they had been diachronic, actually occurring within our personal experience. If I know, as a _historic fact_, that the circle was commenced where I have put my wafer, I may begin it there; but there is, and can be, nothing in the _phenomena_ to indicate a commencement there, any more than anywhere else, or, indeed, anywhere at all. The commencement, as a fact, I must learn from testimony; I have no means whatever of inferring it from phenomena. * * * * * Permit me, therefore, to repeat, as having been proved, these two propositions:-- ALL ORGANIC NATURE MOVES IN A CIRCLE. <sc>Creation is a violent irruption into the circle of nature.</sc> VII. PARALLELS AND PRECEDENTS. (_Plants._) "Where wast thou when I laid the foundations of the earth? declare, if thou hast understanding."--JOB xxxviii. 4. Since every organism, considering it, throughout its generations, as an unit, has been created, or made to commence existence, it is manifest that it was created or made to commence existence at some moment of time. I will ask some kind geological reader to imagine that moment, and to accompany me in an ideal tour of inspection among the creatures, taking up each for examination at the instant that it has been called into existence. Do not be alarmed! I am not about to assume that the moment in question was six thousand years ago, and no more; I will not rule the actual date at all; you, my geological friend, shall settle the chronology just as you please, or, if you like it better, we will leave the chronological date out of the inquiry, as an element not relevant to it. It may have been six hundred years ago, or six thousand, or sixty times six millions; let it for the present remain an indeterminate quantity. Only please to remember that the date _was_ a reality, whether we can fix it or not; it _was_ as precise a moment as the moment in which I write this word. Well then, like two of those "morning stars" who, when "the foundations were fastened," "shouted for joy," we will, in imagination, take our stand on this round world at exactly ---- minutes past ---- o'clock, on the morning of the ----th of ----, in the year B.C. ----. The noble Tree-fern before us (_Alsophila aculeata_) has this instant been called into being by the creating voice of God. Here it stands, lifting up its columnar stem, and spreading its minutely fretted fronds all around, in a vaulted canopy above our heads, through the filagree work of whose expanse the sunbeams play in a soft green radiance. It has this instant been created. But I will suppose, further, that we have the power to call into our council some experienced botanist; who is not acquainted, as we are, with the fact of this just recent creation, and whom we will ask to give us his opinion on the age of this beautiful plant. _The Botanist._--"You wish to ascertain the age of this _Alsophila_. I know of no data by which this can be determined with precision, but I can indicate it approximately. Let us take it in order. The most recent development is the growing point in the centre of the arching crown of leaves. Around this you would see, if your eyes were above the plane, close ring-like bodies, or, perhaps, more like snail-shells, protruding from the growing bud; then young leaves, partially opened in various degrees, but coiled up scroll-wise at their tips, and around these the elegant fretted fronds, which expand broadly outwards in a radiating manner, and arch downwards. "Now every one of these broad fronds was at first a compactly coiled ring; but it has, in the course of development, uncoiled itself, growing at the same time from its extremity, and from the extremity of each of its formerly wrapped-up pinnæ and pinnules, until at length it has attained the expanse you behold. This process has certainly occupied several days. "But let us look farther. The outermost fronds that compose this exquisite cupola, you see, are nearly naked; indeed, the extreme outermost are quite naked, being stripped of their verdant honours, their pinnæ and pinnules, and left mere dry and sapless sticks,--the long and taper midribs of what were once green fronds, as graceful as those that now surmount them. Some of them, you see, are hanging downward, almost detached from the stem, and ready to drop at the first breath of wind. Now remember, each of these brown unsightly sticks was once a frond, that had passed through all the steps of uncoiling from its circinate condition. This whole process has certainly occupied several months. "Look, now, below these withered midribs, lifting up the most drooping of them. The stem is marked with great oval scars; and see, this old frond-rib has come off in my hand, leaving just such a scar, and adding one more to the number that were there before. And look down the stem; it is studded all over with these oval scars. There are a hundred and fifty at least; but I cannot count them nearly all, for towards the lower part they become more undefined, and the growth of the stem has thrown them further apart; and besides, there is, as you observe, a matted mass of tangled rootlets, like tarred twine, which, springing from between the lower scars, increases downwards, till the whole inferior extremity of the stem is encased in the dank and reeking mass. "You can have no doubt that every one of these scars indicates where a leaf has grown, where it has waved its time, and whence, after death and decay, it at length sloughed away. The form of the uppermost, which are not distorted by age, agrees exactly with the outline of the bulging base of the candelabrum-like frond; the arrangement of the scars is that of the fronds; and you may notice in every scar marks where the horseshoe-shaped plates of woody fibre have been broken off, which once passed into the interior of the stem from the midrib of the frond. "These scars, then, are ocular demonstrations of former fronds; we may no more doubt that fronds were once growing from these spots, than we may that the green and leafy arches were once coiled up in a circinate vernation. They are the record of the past history of this organism, and they evidently reach far back into time. The periodic ratio of development of new fronds may be, perhaps, roughly estimated at six in the course of a year. Now there are about a dozen unfolded or unfolding, as many withering midribs, and about a hundred and fifty leaf-scars that we can count with ease, not reckoning such as are indistinct, nor such as are concealed beneath the tangled drapery of roots. [Illustration: LEAF-SCARS OF TREE-FERN.] "I have no hesitation, then, in pronouncing this plant to be thirty years old; it is probably much older, but it is, at least, as old as this." Such is the report of our botanical adviser; such is his argument; and we cannot but admit that it is invulnerable; his conclusion is inevitable, but for one fact, which he is not aware of. There is one objection, however, to which it is open--a fatal one; you and I know that the Tree-fern is not five minutes old, _for it was created but this moment_. Here is another act of creation. It may be the same day as that of the Tree-fern, or one as remote as you please from it, before or after. A few moments ago this was a great mass of rough, naked limestone, but by creative energy it has been suddenly clothed with a luxuriant mantle of _Selaginella_. How exquisitely beautiful the aggregation of flattened branching stems, studded with their tiny imbricated leaflets of tender green, bloomed with blue! and how thick and soft the carpet that thus conceals the angles and points and crevices of the unsightly stone! Broad as is this expanse of verdure, covering many square yards without a flaw, and rooted as it is at ten thousand points of its creeping stem, we shall yet find that it is one unbroken structure. Our friend the botanist would infer unhesitatingly that every part of this widespread ramification has originally proceeded from one central shoot, and that several years' growth must have concurred to form this compact mass. Yet _we_ know that such an inference would be false. The plant has been this instant called into being. On the summit of this rounded hill is a very different plant from the last. Beautiful it also is, but grandeur and majesty are its leading attributes. It is a dense and massive clump of the Tulda Bamboo. How noble these straight-jointed stems, cylinders of polished green, shooting their points right upwards, and towering to a height of eighty feet! The numerous panicles of tufty blossom are gracefully bending from the summits, and from the tip of every branch, nodding in the breeze. There are scores of the tall stems, as straight as an arrow, beset at every joint with diverging horizontal branches, crossing and recrossing in inextricable confusion. And see, amidst the crowd, there are others as thick and tall, but without a single side-shoot, clothed, however, to atone for the deficiency, in swaddling-clothes peculiarly their own. These swathed stems are infant shoots,--vigorous and promising children, indeed; these brown triangular sheaths, covered with down, are the clothing of infancy; they increase in number, and are closer together towards the summit of the shoot, where the growing point is rapidly extending. When the stems have attained their full height, these sheaths will fall off, the polished shafts will stand revealed in their glossy beauty, and the lateral pointed branches will at once start forth from every joint, and pierce horizontally through the dense tangled bush. Now these young shoots do not bear testimony to so great an age as you would suppose. The whole seventy feet of their altitude have been attained within thirty days! But then their massive size and vigour indicate a mature age in the clump. For all the hundred stems that are crowded together in this dense Bamboo-clump are organically united; they are parts of one and the same plant, the root-stock of which has been creeping to and fro year after year, sending up in constant succession its arrowy stems, until it has attained the present magnificence. Many years must have elapsed between the present condition of the grove, and that of the slender blade that shot up from the tiny seed in this spot. Yes, so you may think. But it is not so, for the great Bamboo-clump has been created in its pride and glory this very hour! Yonder is a considerable area of land covered with the green blades of young wheat, and very healthy and strong it looks. No, it is Couch-grass! The whole green sward which we see is a single plant; the creeping stem of which has spread its ramifications in all directions beneath the surface of the soil; and still the long succulent shoots are extending in every direction, as shewn by the green leaf-blades. This is a rapidly growing plant, it is true; yet still there must be an accumulated growth of many months here, if not years! No, it was created this morning. Contrasting with this humble grass, observe that luxuriant Screw-pine. See its singular crown of foliage at the summit of its equally singular stem. Its great prickle-edged stiff leaves grow in long diagonal rows, each sheathing its successor, and alternating with those of the next row. How rich and fragrant an odour is diffused from its crowded blossoms! Every one of those sword-like leaves is, of course, the record of a period of time. A tree of this size makes a "screw," or imperfect spire, of leaves in about three years; and there are about sixteen pairs of leaves in each screw, which will give us nearly eleven leaves for the development of each season. Now, on the trunk, there are numerous waved lines quite covering its surface, which are the traces of old leaves that have in succession been produced and decayed away;--the trunk is, in fact, composed of these leaf-bases. By counting these, we may obtain then an approximate notion of the age of this plant;--an _approximate_ notion only, because in its young stages the development of leaves probably took place more rapidly than it does now. There are then on this trunk about one hundred and fifty horizontal rows of scars, and each row numbers four leaf-bases, so that the trunk is inscribed with an autographic record of six hundred leaves. If then we reckon eleven leaves as the produce of a single season, and add the four screws which are still flourishing, we shall obtain a result of about fifty-five years as the age of this _Pandanus_. This, for the reason just assigned, would probably be considerably too much; perhaps, forty years would be nearer the truth. There are, however, other marks of age here, though they are less definite. The great hardness of the surface-wood, which we perceive on trying to indent it, is an indication of age, as it is produced by the successive bundles of woody fibre, which, year after year, have passed down from each leaf, curving, in their descent, towards the circumference of the stem, and, therefore, constantly augmenting the density of the outer portions. Another very curious proof of age is seen in the number of aerial roots which descend from various points of the trunk towards the soil. You would at first be inclined to think them posts, which a carpenter had set to "shore up" the tree, as props to prevent its being blown down. And truly this is their purpose; but they are natural adjuncts, not artificial. These thick rods, some of which have not yet reached the ground, have been shot forth in turn from the stem, in order to afford it additional support in the loose sandy soil. And mark, by the way, a beautiful contrivance here. Because the growing tender extremity of the root has to pass through the sun-parched air in its progress towards the earth, there is a curious exfoliation of its extremity, forming a sort of cup, which, collecting the scanty dews, retains sufficient moisture for the refreshment of the spongy rootlet. Now, I say, these supporting roots, since they must have originated from the trunk, after the latter had attained a considerable height, are so many evidences--and cumulative evidences--of age, though their testimony cannot be so well made to bear on a known period as that of the leaf-bases. Should we not then be amply warranted in asserting this Screw-pine to be many years old, if we were not assured that, as a fact, it has been this instant created? [Illustration: ROOTS OF IRIARTEA.] A phenomenon analogous to that which we have just observed is presented by yonder Pashiuba Palm (_Iriartea exorhiza_). Its straight arrowy stem has shot up to the height of fifty feet, like a slender iron column. On the summit there is the usual divergent crown of leaves that distinguishes this most graceful and queenly tribe; and at the foot, a tall open cone of roots, strangely supporting the column on its apex. "But what most strikes attention in this tree, and renders it so peculiar, is, that the roots are almost entirely above ground. They spring out from the stem, _each one at a higher point than the last_, and extend diagonally downwards till they approach the ground, when they often divide into many rootlets, each of which secures itself in the soil. As fresh ones spring out from the stem, _those below become rotten and die off_; and it is not an uncommon thing to see a lofty tree supported entirely by three or four roots, so that a person may walk erect beneath them, or stand with a tree seventy feet high growing immediately over his head." "In the forests where these trees grow, numbers of young plants of every age may be seen, all miniature copies of their parents, except that they seldom possess more than three legs, which gives them a strange and almost ludicrous appearance."[53] This tall Pashiuba before us, however, is supported on several scores of roots, in various stages of development, some descending through the air, some already fixed in the soil. As the presence of these, moreover, implies the decay and disappearance of earlier ones, their number and height may be accepted as a fair testimony to the age of the tree; independent of what we might have deduced from the trunk and other sources. (My reader will bear in mind, that, throughout this chapter, I am supposing that we have the opportunity of seeing each organism at the moment following that of its creation.) The _Iriartea_ before us, then, notwithstanding its marks of maturity, is but--a new-born infant, I was about to say, rather--a new-made adult. Another and more massive Palm appears, where a moment ago there was nothing but smooth ground and empty air. It is the Sugar Palm (_Saguerus saccharifer_), remarkable in its appearance for the swathes of what looks to be _sackcloth of hair_, in which its stem is enveloped. Each of its great pinnate leaves forms with the dilated base of its midrib a broad sheath, which springs out of a loose fold of this coarse cloth that is wrapped around it. And not only the bases of the still flourishing leaves are swathed in this natural textile fabric, but the dead and dry leaf-bases of the former leaves, which may be traced all down the stem. But let us look at this strange cloth: what is it? It is composed of the exterior fibres of the leaf-bases themselves, which in process of growth have partially separated themselves, and from which the parenchyma and the lamina have decayed away. The appearance of a woven fabric is deceptive; there is no interlacing; but its semblance is produced by the fibres lying in layers one over the other, and by some of them having a direction at right angles to the others. Originally all the fibres were parallel and longitudinal, but as they have been, in the growth of the leaf, pulled out laterally, the main fibres, which are indefinitely divisible, have adhered to each other at various parts, and the result has been that innumerable constituent fibrillæ have been stretched across from fibre to fibre. Every square inch, then, of this sackcloth tells of the lapse of time; these horse-hair-like fibres were once green and vascular, enclosing a soft pulp; in short, they were a part of a verdant leaf; the reduction of each congeries of veins to this condition was a work of time, and this has been effected by many leaf-bases in succession. An examination of this _gomuti_, as it is called, does not indeed help us to identify the actual interval lapsed in the history of the plant; but we may arrive at this from other considerations. The great sheathing bases themselves remain in numbers attached to the upper portion of the stem, though the greater portion of the midrib with the pinnæ has decayed and fallen; and in the lower part, where even the bases have disappeared, still broad lateral scars are left, marking off the stipe into horizontal rings, which are not less conclusively certain evidences of the former existence of similar bases, and therefore, still earlier, of leaves. The Sugar Palm developes and matures on an average six leaves every year.[54] On counting the dry leaf-bases, and the scars, I find on this trunk, a hundred and twenty: besides which there are about a dozen expanded leaves, and two visible, which are not unfolded. A hundred and thirty-four leaves then have left proofs of their existence here; which divided by six, gives about twenty-two years as the age of this Palm. This is the age of this tree, however, since it began to form a stem; but several years of infancy must be added to the sum, during which its fronds sprang in succession from the surface of the soil. Look at this _Areca_. By-and-by it will grow to the loftiest stature attained by any of its tribe, and its noble crown of leaves will wave on the summit of a slender pillar a hundred and fifty feet in height. But at present it has no stem at all; the widely arching leaves diverge from a central point which is below the surface of the soil. Here, then, are no dead leaf-bases; here are no old historical scars:--have we any evidence of past time here? Yes, surely. See this fully developed leaf. It is composed of a stout midrib, along the two opposite edges of which grow, like the beards of a feather, narrow sword-like leaflets, separated from each other by intervals of about two inches. But this pinnate condition,--which is so inseparable from the developed leaf of a great division of the Palm tribe, that our idea of a palm-leaf almost always is that of an enormous feather,--is by no means the original state. Observe this young leaf which is not yet thoroughly expanded; the leaflets are, indeed, separated everywhere, except that the tips of all are connected by a very narrow ribbon of the common green lamina, which runs from one to another. In the fully opened leaves, this has been torn apart and is not distinguishable. But, let us carefully open this still younger leaf, which is protruding like a thin green rod, or rather like a closed fan, from the centre of the crown. We must handle it delicately, for it is very tender. Now you see it is not pinnate at all; the leaf is as entire as a _Musa_ leaf, which, indeed, it much resembles, except that each half is folded transversely, and then these transverse folds are packed one on another longitudinally, fan-fashion. Each of the transverse folds answers to a future leaflet. It is the development of the midrib in length that tears asunder the divisions of the lamina, and converts them into separate, and by-and-by remote, pinnæ. It is manifest then that every leaflet on the midrib of a pinnate-leaved Palm is a record of past time, as real as the leaf-bases on the trunk, inasmuch as, in each case, there is ocular proof that the conditions of existence are different from what they have been. And yet in this case, the evidences are fallacious, since the _Areca_ before us has even now been created. Here is an extraordinary plant. Though no thicker than your little finger, it will be found almost a quarter of a mile in length.[55] This is a kind of Cane (_Calamus_); its slender jointed and polished stem is encased in the closely-sheathing and tubular bases of the leaves, which are spiny on their midribs, spiny on their pinnæ, and horridly spiny on the long and tough whip-lash in which the point of each leaf terminates. This lengthened cord is studded, at intervals of a few inches, with whorls of stout and acute prickles which are hooked backwards, and performs an important part in the economy of the plant. We see how it sprawls along the ground a few yards, then climbs up a tall tree, runs over the summit, descends on the opposite side to the ground, mounts over another tree, and thus pursues its wormlike course. Now as the pinnate leaves are put forth at every joint, the formidably armed flagellum affords a secure holdfast to the climbing stem, which otherwise would be liable to be blown prostrate by the first gust of wind; the recurved hooks, however, catch in the leaves and twigs of the trees, and effectually maintain the domination of the prickly intruder. It is obvious that every inch sprawled over by this trailing stem supposes all the previous inches of its lengthening course; that every successive joint implies the existence of all the earlier joints; that every whorl of spines involves the development of every former whorl. Yet our reasoning is at fault; there has been as yet no succession; the development has been simultaneous, for it is the development, not of growth, but of creation. Enough of Palms. Look at this _Agave_. Its thick, fleshy, glaucous leaves, with spinous margins and pointed ends, are arranged in many whorls on the summit of a stem, which is scarcely visible, as it barely rises above the soil. From the centre of the crown springs the stately flower-stalk, itself a tree of forty feet in stature, having a cluster of yellow blossoms at the extremities of its candelabra-like branches. Have we here any clue to the past history of the plant? The tall flower-stalk, it is true, is of rapid growth, its whole stature having been attained within three or four weeks. But those massive leaves! Each of these lasts many years, and their development is as slow as that of the flower-stalk is rapid. Certainly we cannot assign to this individual, in the very vigour of its inflorescence, an antiquity less than half a century, and perhaps it may be considerably more. You are altogether wrong; for it is but just called into existence. [Illustration: TRAVELLER'S TREE.] We pass on, and pause before a noble example of one of the stateliest of plants,--the Traveller's Tree (_Urania speciosa_). It is a great Musaceous plant, resembling one of those fans which in the Southern States of America are made by ladies out of the broad tail-feathers of a turkey. Its leaves, of vast size, consist of a broad oblong lamina of the most brilliant green hue, divided equally by a midrib which descends in a smooth cylindrical petiole, much longer than the lamina (which is itself eight feet or more in length). Each leaf-stalk terminates below in a great demi-sheath, out of which springs another, in a zigzag or distichous fashion, the whole diverging, as they rise, in the same plane. Below the alternately-sheathing leaves, of which there are but eight at present existing, there are the bases of others, now dead, which, when alive, evidently followed the same arrangement; and these give place yet lower to rings, each partly surrounding a massive conical stem. I fear we have no criterion for determining the exact age of such a plant as this from actual observations on its rate of growth. From the fewness of its existing leaves they probably endure a considerable time; but at all events here are indubitable evidences of successive generations of leaves which are now past and gone; some of which are represented by withered rib-bases, while older ones have left but the scars which indicate the positions on the trunk where once they stood. Here are distinct testimonies to the lapse of a considerable period of time since the magnificent _Urania_, began its existence. Yet we should err egregiously by giving credence to them, since these developments are all _prochronic_. "What a lovely butterfly!" Nay, it is a flower: though it dances in the air with an insect's fluttering flight, and seems to present in its broad wings of yellow and orange, and in its long and slender members, an insect's form and hues, it is but a flower fixed at the end of a lengthened stalk, which hangs from, a mass of leaves and bulbs, seated in the fork of this huge mahogany-tree. We will neglect the flower, curious and beautiful as it is, and examine this crowded mass of roots and fleshy leaves and oval bulbs. Tracing the slender lengthened footstalk to its origin, we see that it springs from the lower part of a flat, ovate, or nearly round, ridged, pseudo-bulb, of a purplish-green hue, of which there are many, much crowded together. The point of issue of the flower-stalk is concealed by an enveloping husky scale, which is the withered condition of a former leaf. From the base of another bulb a thick obtuse cone is pushing forth, which is the commencement of a new leaf-shoot; and here is one considerably advanced. In this latter there is nothing very remarkable; it is a thick, growing shoot, formed by fleshy leaves nearly doubled together, each sheathed by its predecessor. But soon this will cease to grow, and the point will dilate into an oval bulb, which will be a reservoir of nutriment for the future flower. In fact it will add another to the matted mass of bulbs which are already accumulated, crowned with two great thick, leathery, ovate, brown-spotted leaves, and marked with the scars of the leaves which are now growing, but which will then have sloughed away. In this _Oncidium_, then, we have evidently a record of many bygone processes. Before the flower could open, the flower-stalk must have been developed; before this, the pseudo-bulb must have been formed; before this, there must have been a well-formed leaf-shoot, which must have been first a conical bud pushing forth from some anterior bulb;--or, if that shoot had been the first of the mass, then it must have looked back to a seed, which of course looked back to the capsule of a pre-existent flower, and so on. Yet this is all fallacious; for the Butterfly-flower is but just created. As beautiful, if less curious, is the crowded spike of purple blossom that adorns the tall stalk of this terrestrial Orchis. The flower-stalk springs from the midst of a few large spotted leaves, which terminate below in an irregular fleshy tuber of glutinous consistence. This tuber is shrivelled, and is in process of exhaustion and decay; but a horizontal stem has pushed out underground, which has at its extremity a second tuber, as yet immature, but plump and swelling. This growing tuber contains the elements of the leaves and flower-spike of next season: the shrivelling one was, last year at this period, in exactly the same condition as the swelling one is now; it too was pushed out horizontally from a preceding one which was then shrivelling, and so backward. These pre-existing stages can with certainty be announced by the vegetable physiologist; who yet would be deceived in this instance, because the plant has been but just created. This elegant _Gladiolus_ that displays its tall spike of crimson blossoms from the midst of its flattened folded leaves, affords us a similar example of retrospective energy. If I dig away the light soil from around its base, I discover two globose corms, fleshy swellings of the stem, accumulations of nutriment obtained during the vegetative activity of the plant, and destined to support it during the season of inaction, and therefore stored up for that purpose. [Illustration: CORM OF GLADIOLUS IN JUNE.] The uppermost of these globose corms is that of the present season; it is as yet small and immature, being in process of formation by the assimilation, consolidation, and deposition of new matter by the action of the leaves. This is sheathed in the tubular bases of the leaves, which expand above; and it is seated on a larger, riper, and more spherical corm, which is wrapped in a brown fibrous skin. This is the matter which was deposited in the course of last spring and summer, and the brown skin is the remains of the leaves of last year. This corm has remained inactive, since the decay of last year's leaves, until this winter, when the root fibres, which we see descending from the lower surface, began to form, and an upward prolongation of the stem followed, which, as it grew, swelled into the upper corm. In the centre of the under surface of the corm of last season, in a depression surrounded by the white root-fibres, there are some almost decayed remains of a deep brown hue. These are the last vestiges of the preceding year's corm, and they exhibit the condition in which the large corm will be next spring, when the small half-formed one will be in the state and position of this larger one, and will in like manner be surmounted by its rising successor. Thus there are in this plant ocular proofs of two years' history before the present; yet these proofs are invalidated by the fact of its creation this day. Behold now that singular plant, the Grass-tree (_Kingia australis_), displaying what seems an immense tuft of wiry grass elevated on the summit of a trunk which is formed of the united bases of myriads of decayed leaves, the representatives of many generations of these organs. The silvery leaves which constitute the existing crown, and the numerous spikes of blossom which stand up in a circle diverging from the midst of them, give to this plant a most striking effect. That, however, is not our present concern, but the evidences which we may be able to gather from it of a previous history. For some distance below the living leaves, the trunk is connected by the withered, hanging, but still persistent leaves of several successive developments, a ragged drapery, of which we might certainly say-- "----when unadorn'd, adorn'd the most." The lower portion of the stem is, however, destitute of the decayed leaves themselves, the lozenge-formed bases of them alone remaining, still separable, indeed, but sufficiently compact to make in the aggregate a sub-cylindrical column of loose texture, which may in familiar parlance be termed a _trunk_. This portion is marked by alternate enlargements and constrictions of the outline, which appear to indicate seasonal growths. The specimen before us is about twenty feet in height, exclusive of the crown; supposing these swellings to mark a year's growth, and to be continued in the same proportion on that part of the trunk which is masked by the decayed leaves as on the exposed part, we should conclude this tree to be about thirty-five years old; for there are about thirty-four such swellings, each of which contains about four hundred of the lozenge-shaped bases of the fallen leaves.[56] Remember, however, that we are looking at the Grass-tree, not as it now appears on the sandy plains of Western Australia, in the nineteenth century, but as it came out of the hands of its Almighty Creator at some precise but unknown period of past time. This White Lily, crowned with its cluster of nodding flowers, magnificently beautiful, each a fair emblem of the spotless purity of a noble virgin--if we remove the soil from its base, we shall find that the stem springs out of a fleshy bulb. This is covered with thick yellow scales, by taking away each of which in turn, we see that the bulb is made up of such, surrounding the central mass which has pushed upward, in the form of the stalk, with its leaves and flowers. [Illustration: SECTION OF LILY-BULB IN JULY.] Now the whole of this beautiful array which we see was formed last summer, when, if we had divided the bulb longitudinally, we should have seen every leaf, every tiny blossom, folded together, and most snugly packed within the encircling scales, which are, indeed, undeveloped leaves; while from the base of the bulb so formed we should have seen pushed up on the outside of it, but yet within the common envelope of the exterior scales, the flower-stem of last season. There could not possibly have been this raceme of virgin blossom, if it had not been formed during the preceding season within the bulb; so that its existence is a record of a year's growth at least. Yet this is the first hour of the lovely Lily's life; an hour ago it was not. The face of the rugged cliff that rises perpendicularly above us was, a few moments ago, quite naked and bare, or diversified only by a few stunted prickly shrubs that sprang from its crevices. Now, by the mighty fiat of God, it is in an instant festooned from top to bottom with a most graceful drapery of round pale-green leaves, and slender stems no thicker than whipcord, and multitudes of spiral tendrils that climb, and hook, and catch, and entwine among the thorny bushes, and around the angles and prominences of the rock. We trace this curtain of verdure downwards, and find that it resolves itself into some half a dozen of wiry-stems, that issue from different points of the surface of what seems a boulder of brown stone, or a block of rough-hewn timber, at the foot of the cliff. [Illustration: TESTUDINARIA.] This angular block is, however, worthy of closer examination. It is of no definite form, huge and uncouth, lying as if cast accidentally on the ground. Its whole surface is divided into a multitude of polyhedral pieces, that look as if they had been cut into these forms by human art. Each division has a small angular face, and its sides display close parallel lines, all following the directions and angles of the outer face, but each line enclosing a slightly wider area than the one above it. These woody plates closely resemble in their angular forms and their concentric lines the plates of a Tortoise's shell, and hence our botanical friend, to whom we will appeal for an opinion as to the age of the block, will call the generic name _Testudinaria_. "Well, I cannot give you any very precise judgment on the matter. The block itself is the tuber of a sort of yam, which grows above ground instead of below. It is a woody mass of great age. The angular plates are the bark, and they are so divided in consequence of the gradual growth of the tuber, tearing open its periphery to obtain more room. The concentric lines on the edges of the plates will not give us any adequate idea of the age of the mass, for though they indicate seasonal growths, the earlier layers have been worn away in the lapse of ages, and there are many layers of bark that have not yet been burst by the expansive force of the growing wood. It is known that these blocks are of very slow growth; in tropical regions they last, with scarcely perceptible increase, from generation to generation. From such vague data as we possess, I might loosely conjecture this tuber to be a thousand years old." We thank our scientific friend, and think it a very satisfactory report on an organism, which we saw called into existence five minutes ago, before our eyes. Come away; for I wish you to look at this _Encephalalartos_. A horrid plant it is, a sort of caricature of the elegant Palms, somewhat as if a founder had essayed a cocoa-nut tree in cast iron. Out of the thick, rough, stiff stem spring a dozen of arching fronds, beset with sharp, sword-shaped leaflets, but having the rigidity of horn, of a greyish hue, all harsh and repulsive to excess. In the midst of this rigid coronal sits the fruit, like an immense pine-cone. The swelling column that constitutes the stem is but a mass of pith, surrounded by a thin case of wood, and enclosed by the remains of former leaves. The whole surface is covered with the lozenge-shaped scars of these, in vast number. Thousands of these there must be in this trunk of eight feet high, and a foot thick. The leaves of the existing crown are few and very durable, so that it would be no unreasonable conjecture to suppose that this great Cycadaceous plant is seven or eight centuries old. [Illustration: ENCEPHALARTOS.] Nay, for this also has been created even now! What shall we say to _this_ singular phenomenon? Observe yonder gigantic Fig (_Ficus Australis_) growing out of the face of that vast rocky precipice. It is not so much to the massive grandeur of the trunk, nor to the widespread head of dense foliage, that I call your attention, as to the broad expanse of roots, from the thickness of your body to that of your little finger, which have crossed and interlaced and separated and re-united, in all imaginable ways, until the whole forms a great flat network of wood, investing the surface of the rock, and following all its projections and angles with singular faithfulness, for a space of many square yards. Would you not say, admitting that the Figs are rapid growers, that many years must have elapsed since the minute seed was dropped in yonder crevice, by some vagrant parrot that wiped his beak after breakfast on the point of rock? Would you not say that many years must have passed from the time when the tiny shoot peeped from the rocky chink, to the present moment, when the leafy honours of the crown above and the woody wall of the roots below combine to repay the protection which the plant in infancy received from its stony foster mother? Of course you would; and most truly too, did you not know that the Fig-tree is now rejoicing in the first hour of its new-created being. So with its noble congener here, the many-trunked Banyan (_Ficus Indica_). Although not an old tree, its canopy of broad downy leaves is already supported by so many secondary trunks, that it is not easy to say which of the larger stems is the mother trunk, and which the hopeful daughters. Every one of these stems, some just protruding from the horizontal limbs, others hanging midway between the leafy roof and the earth, some just inserting their slender spongy tips into the soil, others thick and pillar-like--is an evidence of progressive development, and therefore of lapsed time; only for the qualifying fact, that the development in this case is _prochronic_. Here is the great _Euphorbia grandidens_ of Africa. Its stout trunk is marked with a number of holes, some four or five inches apart, arranged in perpendicular rows. In some cases they are rather depressions or pittings than holes, and look like what would result from borings made with an auger in pitch in warm weather, the margins of which had nearly closed, subsequently. What is the explanation of these marks? They are all records of time. From each of these spots once grew one of those angular prickly branches, that look like our commonest sorts of _Cactus_, and which are now confined to the summit of the trunk, arching out from it, somewhat like the branches of a candlestick. It is the habit of this plant, when the stem has acquired a certain thickness, that the branches should, after a time, decay and drop off at the point of their union with the trunk, or rather a little below the surface, so as to leave the shallow holes or pits which we see. After their decadence, the growing bark gradually swells around the scars, and has a tendency to obliterate them. This may account for the non-appearance of them on the lower parts of the stem. Here, then, are demonstrations of several successive stages of development. First, the stem must have been in existence before any lateral branches could have sprung from it. Secondly, the branch shot out. Thirdly, it put forth its spines and leaves. Fourthly, it died and sloughed away. Fifthly, the growing bark encroached on, and finally obliterated the cicatrice. In this individual, all these stages are illusory, or rather they are prochronic. See this noble Tulip-tree (_Liriodendron tulipiferum_), a giant of this primeval forest; its towering trunk is crowned with a head of large massy foliage, of a rich deep verdure, among which shine numbers of great golden tulip-like blossoms, as fragrant as beautiful. It is, however, the leaves that grow on the terminal twigs that I wish you specially to notice. These, which, as you see, are large, and of a remarkably elegant form, are fixed at the end of long petioles, which are set alternately on the twig. Notice, now, the manner of their development; the young unexpanded leaves grow within two large leaf-like bracts, forming an oval sac, which, as the young leaf increases, swell, and at length burst, and are left on each side of the base of the leaf-stalk. There is a succession of these. On this growing twig, for instance, I find three leaves already expanded (_a a a_ in the accompanying figure), and as many pairs of these bracts (_b b b_) at their bases; the twig is terminated by a pair (_c_) convex outwardly, and whose edges are in contact with each other; if, now, I cut off one of these (as represented at _d_), I expose the next leaf (_e_) folded together, and bent downward, in its pretty manner of _vernation_; beside it is another pair of bracts (_f_), whose edges are not only in contact, but mutually adherent, and that with considerable force. On tearing these apart, I discover another smaller leaf, and another smaller pair of adhering bracts, which again contain a similar set, only yet more minute, and so on in succession, till I can no longer trace them. [Illustration: TWIG OF TULIP-TREE.] Now it is manifest that the uppermost of the three leaves, together with the developing terminal bud, was at one time enclosed in the pair of bracts immediately below its base; that, before that, the middle leaf, with all above it, was similarly incarcerated in its own proper tracts; and, at a period anterior to that, the lowest leaf also. Each pair of bracts is therefore a record of a past period; and together they testify to a succession of past periods. And yet their combined testimony is utterly worthless, because the noble tree was created in its magnificence this very day. The beautiful twiner (_Bignonia_), which has cast its ample festoons over the topmost branches of yonder towering Mora-tree, almost concealing the natural foliage with its own elegantly pinnate leaves, and adorning it with its gorgeous trumpet-shaped flowers, is distinguished by a curious property, indicative of the years that have passed over it. In its adult maturity, as we now see it--the glory of this tropical forest--we should find, if we cut across the main stem, that its wood is divided into lobes arranged in a radiate or star-like fashion, like the divisions seen on dividing an orange transversely; and these lobes are thirty-two in number. But this condition has not existed through the life of the plant. The wood has always been lobed, but the number of the divisions has varied, and that in geometrical ratio. Before the present stage, the constituent lobes were sixteen, which became thirty-two by the subdivision of each. In an earlier stage there were eight lobes, and, earlier still, four, which was the commencing number; the duplication having proceeded in each case by the fission of each of the existing lobes into two.[57] Now though this phenomenon will afford us, on the data we at present possess, no insight into the age of the plant, considered as an actual chronological period, an examination of a transverse section would always determine which stage is then present, and, by consequence, how many previous stages have been passed through. And thus we obtain a distinct clue to the former history of the organism, though we cannot mark it off into months and years. Yet the fact of creation stultifies all the conclusions that we might form from such premises; since it does, _ipso facto_, contradict every such thing as a previous history. On this _Anona_ there is an intruder more strictly parasitical; it is a _Loranthus_, with long, club-shaped, richly-coloured blossoms. The branches of the supporting tree--a nurse who feeds her foster-child on her own vital juices--are over-spread for a large space with the shoots; which, springing each from its own disk, appear like so many distinct individuals, but are really all parts of a single plant, springing from a single seed. (For this curious fact we are indebted to the observations of Mr. Griffith, who has investigated the singular history of these parasites.) The ripe seeds firmly adhere to the substance on which they are applied, by means of their viscid envelope, which soon hardens into a transparent glue. In the course of two or three days, the radicle curves towards its support, and, as soon as it reaches it, becomes dilated and flattened. An union is gradually formed between the woody system of the parasite and that of the stock, after which the former lives exclusively on the latter, the fibres of the sucker-like root of the parasite expanding on the wood of the support in the form of a _paté d'oie_. Up to that time the parasite had been nourished by its own albumen, which is now exhausted. As soon as the young parasite has acquired the height of one or two inches, when an additional supply of nourishment is required, a lateral shoot is sent out, which is, especially towards the point, of a green colour. This at one, or two, and subsequently at various points, adheres to the support by means of sucker-like productions, which are precisely similar in structure and mode of attachment to the original seminal one. The fibres of the parasite never penetrate beyond their original attachment; in the adult the sucker-bearing shoots frequently run to a considerable distance, many plants being literally covered with parasites, all of which have originated from one and the same seed.[58] [Illustration: YOUNG PLANT OF LORANTHUS.] In this case, again, how delusive would be any inference of actual lapse of time deduced from the condition of a plant, which had been created as an adult capable of reproducing its race! Here is a great impenetrable thicket of Prickly Pear. The delicate sulphur-hued flowers expand their broad bosoms to the sun, and the swelling fruit beneath is already putting on its lovely blush of crimson. How curious are the leafless but leaf-like dilatations of the stem--these flat oval plates of parenchyma, studded with clusters of woody and most acute spines!--Every one of these expansions is an expression of time, as they are of course successive, though several may be formed in a single season; and not only so, but the tufts of spines, which grow at the points of intersection of crossing lines, in a network pattern, are all successive, appearing in turn as the expanded joint of the stem grows out. The jointed dilatations themselves are, however, transitory; in the slow lapse of years the common woody axis enlarges, and the interspaces between the oval plates become gradually filled up with cellular tissue, and thus are obliterated; the stem, as may be seen in the central part of this spreading thicket, becoming round, almost smooth, and of dense woody texture. "This condition is the result of many years," you say. It is so, in the ordinary course of nature; but in the case before us, it has been educed in a totally different manner, and by a totally different energy, viz. prochronically, by the omnipotent fiat of the Creator. We have emerged from the forest glooms, and are come within the light and the music of the sparkling sea. And here at its margin, washed by its wavelets, there has been suddenly created a Mangrove tree (_Rhizophora_), destined to be, doubtless, the fruitful parent of a grove, which by and by will fringe this flat and muddy shore for miles, shutting out the light and air which now freely play over the beach, and keeping in, beneath a long canopy of dense and leathery foliage, the murky vapours which will rise from the decomposition of its successive exuviations. As yet it is a single tree, but in its perfection of maturity. And see how characteristically we find here that singular structure, or rather habit, which in Mangroves of normal development would be the effect of age. The trunk springs from the union of a number of slender arches, each forming the quadrant of a circle, whose extremities penetrate into the muddy soil. These are the roots of the tree--there are no others--that shoot out in this arched form from the base, or "crown" of the stem, taking a very regular curve of six feet or more in length before they dip into the mud. The larger arches send out secondary shoots from their sides, which take the same curved form, but in a direction at right angles to the former; and thus a complex array of vaulted lines is formed, which, to the crabs that run beneath--if they were only able to institute the comparison, must be like the roof-groins of some Gothic church, supposing the interspaces to be open to the sky. Now, normally, it would require a lapse of several years from the first dip of the radicle of the seed into the soft soil, to form these arches, and to lift the axis of the tree a foot or eighteen inches above the surface. But here the same result is achieved in a moment, by the exercise of creative power. Look at this _Eriodendron_. What a magnificent accumulation of vegetable cells is here! Its colossal trunk rises in naked majesty, a massive column, to the height of a hundred feet, without a branch. And then what branches! Those limbs themselves are of the bulk of ordinary forest trees; they break out, three or four on the same plane, and radiate horizontally to a vast distance, supporting a noble flat "roof of inwoven shade." [Illustration: SILK-COTTON TREE.] Perhaps the most remarkable feature of this majestic tree is found at the foot of the trunk, which sends out vast spurs, radiating in all directions, and extending to a circle of seventy or eighty feet in diameter. These spurs take the form of perpendicular walls of timber, commonly not more than six or eight inches thick, pretty equal in their thickness throughout, and varying in height from fifteen or twenty feet, where they spring from the trunk, to the point where they enter the soil. Now the Silk-cotton tree has not had this form through its life. When young, say up to twenty or thirty years old, there was no appearance of spurs; the trunk was covered with a green bark, and was studded with great triangular low spines, an inch in diameter. And, what had a curious effect, the middle of the stem swelled into an ovate form, quite symmetrical on all sides. But, as years passed, the ventricose form of the trunk was gradually lost; the bark became of a hoary grey hue or even almost white; the three-sided prickles disappeared from the bole, and were retained only on the upper surfaces of the limbs; and the great lateral buttresses began to fill up the angles which had hitherto existed between the trunk and the main horizontal and superficial roots. I called the noble tree before us an accumulation of vegetable cells. And viewed in that aspect, what an irresistible evidence of the lapse of time does this vast organism present to us! since the whole of this immense structure originated in a single cell, which, by repeated acts of self-division[59] (or, possibly, other modes of reproduction), has gradually built up the mass. Yet such a retrospect would be most fallacious in the case before us, since the plant, as a perfect compound organism, with its parts--root, trunk, limbs and leaves, and its tissues--cellular, fibrous, and vascular, has been produced by the instantaneous putting forth of the Divine volition. Once again. More gigantic even than the towering Ceiba, this immense Locust-tree (_Hymenæa_) appears to penetrate the very sky with its crowd of foliage, which is so remote from the earth, that our eyes cannot avail to discern the forms of the leaves. The straight columnar trunk, like some triumphal monument in the midst of a great metropolis, is of so vast a bulk that a dozen of such men as you and I could scarcely embrace it with stretched arms and joined hands.[60] Can our friend, the vegetable physiologist, help us here to form a notion of the time which would be required for the production of this tree in the ordinary way? It is the last favour we will ask of him to-day. Come, Sir, give us your thoughts on the matter. _The Botanist._--"There is a principle which, in trees of this character, namely, such as are of exogenous structure, will determine the age with very close accuracy. Each generation of leaves sends down woody fibres, which unite into a cylinder on the outside of the wood previously formed, and beneath the bark." "Now, as these cylinders are in general sufficiently distinct, in those trees which renew their leaves but once in a year, it will be enough to count the concentric circles which appear on a transverse section of the trunk, and we shall obtain the number of years during which the tree has existed. In the case of this great Locust, the rule, to be sure, is rather difficult of application in that way; a transverse section of this trunk would cost a little labour. But with this circular saw, which I always carry about with me for investigations of this sort, I can take out a horizontal cylinder on each of two or three sides of the tree, by counting the layers in which I can form a tolerably accurate estimate of the number in the whole diameter. [Illustration: SECTION OF EXOGENOUS TREE.] "See; in these cylinders, which do not materially differ, there are seventy-two layers in a foot, that is, each layer is one-sixth of an inch wide. The trunk is, at the part I have tested, about fifty feet in diameter, or twenty-five feet in radius; which would therefore contain just eighteen hundred such layers. As the deposition of new wood, however, is generally more abundant in youth and middle life than in age, the layers are probably a little wider, that is, fewer in a given space, as we approach the centre. For this we must make allowance, and may conjecture that this tree is probably not less than one thousand five hundred years old." Now whether the premises of the botanist will bear out this conclusion or not, is not a vital question. For the question at issue is, not, _How long_ it has lived, but, _Whether it has lived at all_, before the present moment. It is enough for our point that the tree does, in its concentric zones, afford ocular evidence of successive epochs of growth. And the proof of this would be equally good, if ten layers were deposited in a year, or if one deposit were made every ten years; equally good, if there were fifteen hundred zones, or if there were but five. It would be easy to confirm the testimony of the zones by that of other parts of the structure. The dimensions of the tree itself bear a fixed and, to a certain extent, recognisable ratio to its age; every leaf on a given twig has been successively developed from a leaf-bud, the opening of which and its elongation into a twig occupied, normally, a definite period; each bough, each of those mighty limbs, was once a twig, was once an undeveloped leaf-bud, whose expansion to its present condition was a process, of which time was an inseparable and, within certain limits, a mensurable element. If, then, we were precluded from examining any other organism, as it proceeded from the formative hand of its Creator, than this single tree, we should be amply warranted in inferring a past existence (be it longer or shorter, which is no matter) from the phenomena of its structure, which inference the fact of its creation would flatly contradict. VIII. PARALLELS AND PRECEDENTS. (_Invertebrate Animals._) "There is a kind of character in thy life That to th' observer doth thy history Fully unfold.----" (_Shakspeare._) Leaving the vegetable kingdom, those organisms which, though beautiful indeed and instructive, are yet inanimate, let us seek others which are endowed with a higher style of life, a life which is distinguished by a measure of consciousness of the exterior world, and a perception of relations to it. Let us look for animals. We retrace our steps to the verge of the rippling sea, where the belt of umbrageous Mangroves fringes its margin. Beneath the arching roots of these are now reposing in the warm sunlit shallows many creatures which number this as the first day of their existence. It is their natal, or rather (to make a word) their _creatal_ day. Here is a specimen of the Sea-pen (_Pennatula_), closely resembling a rather thick and fleshy feather, with its quill-end inserted in the tenacious marl which constitutes the floor of the sea along this shore, and with the greater part of its body, including all the pinnated portion, erect, and waving lightly in the gentle swell of the bay. Its central stem is beset on each side with about twenty-five horizontal purple pinnæ, and each pinna bears from five to fifteen polypes with eight tentacles each. Let us wade out to yonder reef. See this great mass of Millepore, growing in thin irregular perpendicular plates, which join each other at various angles, so as to form a large open honeycomb-like structure, much resembling the second stomach of an ox. It is covered with what appears a thin stratum of fawn-coloured jelly, but this consists of innumerable disks, which protrude from myriads of orifices not larger than those produced by the punctures of a fine needle; as we may discern by touching the soft slimy surface, when the whole retires, and leaves apparent only the white stony surface dotted with numberless holes, within which the disks have disappeared, and whence they will again presently re-appear. Here too is a massive shrub of stone, a noble example of the Muricated Madrepore. It consists of a great multitude of short tranches, which are themselves branched and branched again, every part covered with little mammillary warts, and pierced with innumerable holes in which stand radiating plates of the common stone. Out of these plated orifices, especially those towards the tips of the branches, for the older ones are empty and dead, we see perpetually peeping forth, expanding for an instant, and then coyly withdrawing, lovely little green disks, surrounded with thread-like tentacles; and from the extreme end of each branch there protrudes one exactly similar to the rest in all respects, except that it is nearly twice as large. Here then are the living architects; these have secreted within their gelatinous membranes the calcareous atoms, whose aggregate forms the stony shrub before us. Shall we try to estimate the number of polypes that have been occupied in building this tree? There are about a hundred branches, which, taken one with another, and followed along the sinuous course of their many branchlets, we may estimate to average a continuous length of eight feet each; that is, 800 feet of branch in all. Now we may consider these branches as averaging a thickness of two inches and a half in circumference, which gives us a surface of 24,000 square inches. Finally, there are about ten polype-cells in each square inch; and thus there are or have been in this coral-mass, nearly a quarter of a million of polype inhabitants. [Illustration: MURICATED MADREPORE.] But look at this dark crimson edifice of many stories, tier above tier, each horizontal floor of red stone sustained by a multitude of slender cylindrical pillars. When we look closely at them, we see that the pillars are tubes, perforating one or more of the floors, from the lowest tier to the uppermost. Have we any clue to the age of these corals, or to that of either of them, supposing we did not know that they have been created to-day? Not definitely, perhaps; but indefinitely we have, certainly. In the case of the Sea-pen, the polypes have all been formed in succession; as also in that of the stony Millepore and Madrepore, with this addition, that every newly formed polype deposited an increase to the stony substance, which thus went on increasing till the great foliated or ramified mass that we see was formed.[61] And so, with this series of floors and pillars, which is the solid portion of another coral-polype, the Organ-pipe (_Tubipora musica_). [Illustration: ORGAN-PIPE.] Every one of these stories has been formed in succession. From the tips of some of the tubes we see protruding an elegant polype of an emerald-green hue, having eight starry tentacles, and giving off from its base an enveloping membrane, which spreads over the rim of the tube and descends on the outside to the floor. By means of this vascular membrane, both tube and floor have been formed. Calcareous particles, deposited, one by one, in its substance, gradually built up the tube of the primary polype, or probably the tubes of the first series, the basement or ground-floor. When these tubes had arrived at a certain height, all simultaneously began to develope the fleshy membrane horizontally, which expanded until that from each touched that from its neighbour, with which it united. Meanwhile the calcareous deposition went on in this horizontal layer, and thus the first floor was made. Now from the living vascular upper surface of this layer sprang up at certain spots buds,[62] offshoots of the common flesh, which soon rose into columns, and, by a process of calcareous deposition, became tubes with terminal polypes, which in turn spread out a horizontal layer, and thus the second floor was built. Hence a new race of polypes budded, which by and by formed the third floor; and so on in succession, until the series had attained the height which we see. If we assume one of these stories to be the growth of a year,[63] we have ocular evidence in this specimen of six years' age, for here are six successive floors. But no: for it was created complete, as we see it, this very hour. Yonder goes a _Medusa_, pumping its way laboriously, yet not ineffectively, just beneath the surface of the clear wave. It is a great affair, nearly a foot in diameter. Have we, from merely examining its appearance and structure, any criterion by which we can guess whether it has lived an hour, or a year, or ten years? Surely we have; for this mass of clear jelly is composed, like all other organic bodies, of cells, which have been gradually generated, by nutrition and assimilation, from the embryo.[64] This process must have occupied many months, if not several years; but the history of this Medusa did not begin when it took its present umbrella-like form. Shall we trace it back a little farther? At some time back, then, this creature detached itself as the terminal one of many little saucer-like bodies, which had been for some time previously forming by the gradual constriction of a thick fleshy stem. Before the constriction began to be visible, this stem was the body of a white Hydraform polype, affixed by its base, and furnished at its free extremity with thirty-two tentacles. It had lived several years in this form, developing many Hydroid polypes, just like itself, by successive gemmations. Before it took this shape, which it assumed gradually, its tentacles being developed in geometrical progression, 32 from 16, from 8, from 4,--it was a soft ovoid planule clothed with vibratile cilia, which swam freely in the sea, like an _Infusorium_. Thus the physiologist would confidently assign to this Medusa an existence of several years, as an independent organism; _nor could his conclusions be controverted_, except by the knowledge of the fact that the Medusa _has been but just now created_. We pass on. Here is an _Echinus_. Let it be borne in mind still, that we have, _in idea_, the power of pursuing our researches on each creature at the moment which follows that of its creation; and that, when that actually was is of no consequence to our investigation. Here then is this new-made _Echinus sphæra_, a somewhat conical globe of three inches diameter, which is covered with a forest of spines, pedicellariæ, and suckers, and which glides majestically along, with an even but slow progress, over rock and reef. Its vitals are enclosed in a hollow box of calcareous shell, which is built up of nearly a thousand pieces. This specimen, which is rather below than above the average size, is formed of ten meridional rows of large plates (the interambulacral), and ten of small (the ambulacral). The former series are each composed of thirty-two plates, making in all three hundred and twenty; the latter have just double that number, making six hundred and forty; thus this Urchin's box is built up of nine hundred and sixty plates; every one of which is of definite shape and angle, and fits into the angles of its fellows with the accuracy of the most skilfully constructed cabinet-work. Now every one of these plates is an eloquent witness to the past life-history of the Sea-urchin. For the reason why the enclosing box is made of so many pieces is, that it might gradually expand and enlarge its capacity with the ever increasing requirements of the soft organs within. Every plate is enveloped by a vascular flesh, from which the calcareous particles are deposited in a constant and perfectly uniform ratio; and thus all the constituent plates are continually enlarged by additions to both the internal and external surfaces (increasing their strength), and to their sutural margins (increasing their combined capacity), until the adult dimensions are attained. The size of the new-born Echinus is not nearly equal to that of one of these plates, and the progressive increase of the plates by deposition on their edges has certainly taken several years to accomplish.[65] The same result is inferrible from the structure of the spines with which every plate is armed. Each of these is a very long cone of calcareous matter, arranged in minute oval chambers, divided by thin glassy walls, and deposited particle by particle from the thin stratum of living flesh with which each has been invested from its first embryonic development. But of this _Echinus_, as of the _Medusa_ before, we find a history anterior to either box or spines. Its first appearance in this stage of existence was as a barely-visible circular disk, constructed on the outside of the stomach of a singular transparent organism, much like a Medusa, but of a domular form with four or six legs, stiffened by calcareous rods, and a crowning pinnacle. For some undefined time this gelatinous dome had been gliding with a stately movement through the open sea, before there was the least trace of the disk, which afterwards grew to the _Echinus_. In its earliest condition the dome itself was a soft, spherical, mulberry-like _Infusorium_, covered with vibratile cilia; this altered its form to that of a three-sided pyramid, and this to the vaulted dome. Clearly, therefore, we have a right to infer a past history of the Urchin, and that of not a few distinct stages. But no; the specimen has commenced its history within an hour! Yonder Feather-star (_Comatula_) notice; which, having just now started into mature life at the almighty fiat of its Creator, goes careering joyously through the sea, expanding and contracting its many-jointed and feathery arms, as if it had been accustomed to the alternation for a long life, and ever and anon settling itself by grasping the points of rock with its dorsal claws. You would hardly think that those flexible and slender arms were made of stone: yet they are; every joint of the stems and of their pinnæ is a vertebra of stone (precious stones, you will say--topaz and ruby--from their brilliant hues), which has been formed and deposited atom by atom, by the slow and gradual process of secretion of calcareous matter; the lime having been primarily collected from the sea-water which held it in solution. At least, such is the physiological deduction. [Illustration: COMATULA AND YOUNG.] But there was a period in the _Comatula's_ history when it was not a free-swimming star, but a lily-like flower of ten slender fringed petals, seated at the summit of a long stalk, with a central columnar axis of stone. Before that, the flower-head had a bud-like figure, and the petals were minute and destitute of lateral fringes; and earlier still, it was a tiny gelatinous club without any development of stone, affixed by a spreading base, and shooting forth from the top a few pellucid processes. Earlier still, it was, no doubt, an infusory-like gemmule, clothed with cilia. Through all these successive stages, which, of course, occupied a considerable period of time, we should certainly affirm the Feather-star to have passed, did we not know that it has this very hour burst into existence. That Panther, whose tawny fur studded with black rosettes appeared so beautiful as he bounded with agile grace from glade to glade just as we emerged from the forest, contains within his intestines, though you cannot see it, a mature Tapeworm. The body of this parasite consists of some hundreds of square flattened segments, each of which includes a complicated generative apparatus, equal to the production of thousands of fertile ova. Is not this an evidence of age? For, first of all, consider that the formation of each of these hundreds of joints has been a work of development from the anterior parts; and therefore they record as many distinct and successive processes as there are segments. And, secondly, remember that the _Tænia_ did not commence existence as a _Tænia_, nor in the conditions in which it now exists, within the bowels of the Panther. It looks back to another form, and to another living _nidus_. There was a time when this parasitic creature had no ribbon-like body of flattened generative segments. There was, indeed, the same curious head, a tiny globose knob at the extremity of a slender neck, furnished with the same array as now, of rows of hooks and sucking disks. But in place of the segments, the neck merged into a membranous bladder distended with clear fluid. It was not a _Tænia_ then, but a _Cysticercus_. Its home was at that time the interior of a living animal on whose vitalized juices it was sustained, but that animal was widely different from its present patron. It was an Antelope, that cropped the wiry grass and aromatic shrubs of the arid plain. Earlier still, the germ of this _Tænia_ was an egg lying on the ground, having been discharged from the rectum of another Panther, in the bowels of which it had been developed by one of the segments of a former _Tænia_. Let us now trace the history of this organism onwards from the point at which we have arrived in our retrograde researches. The parent _Tænia_, still snugly ensconced in its obscene abode, partially matured and then separated the ultimate generative segment, containing many thousands of ova, far advanced towards perfection. The detached segment now became enclosed in the fæces of the Carnivore, and was at length discharged, enveloped in the pellet. The eggs, acquiring maturity, were hatched, and the infant worms individually scattered themselves among the surrounding herbage.[66] One of these was devoured with the herbage by a grazing Antelope, and having safely escaped the perilous ordeals of mastication and rumination, passed into the stomach of that Ruminant, whence it soon made its way by some unknown but unerring route to the liver, in the parenchyma of which organ it rapidly developed the cyst, which gave to the present stage its proper character. The Antelope fell a prey to the ferocious Cat; its flesh was quickly digested in the stomach, but the gastric juice produced no effect on the _Cysticercus_. This parasite had merely changed its residence for one more commodious, or at least more suitable for its further development. It presently attached itself to the walls of the intestine by means of its oral hooks and suckers, and, getting rid of its vesicular sac, with its fluid contents, probably by absorption, it began to develop, joint by joint, that immense ribbon, which it possesses now, and which constitutes it a Tapeworm. Such is the "strange eventful history" of this repulsive creature; a history legitimately deducible, in all its stages, from its presently-existing condition. But it is a history altogether illusory. The _Tænia_ never was a _Cysticercus_: the Panther is as yet guiltless of capricide: it is this moment called into being, and the Tapeworm begins existence within it. This lump of red sandstone that has been rolled about in the sea, till all its points and angles are worn smooth, is now roughened again by the close and firm adhesion of extraneous substance, in the form of a cluster of shelly pipes, which twine irregularly over the surface of the boulder, and then start up erect with open mouths. These are the tubes of a species of _Serpula_, and the worm itself is seen now slowly emerging from one of them, and introducing its conical stopper, and elegant fans of white and scarlet filaments, to the genial daylight. Observe, however, that the tubes are not of the same diameter throughout. At the point where they start up from contact with the stone, they are considerably smaller than at the tip; and if we trace back the adherent portion along its tortuous course, we find that it constantly diminishes until it is but a slender white thread of stone. Now this slender extremity was formed first; and as the worm itself grew, so it progressively required a larger and yet a larger habitation; which was readily provided of the due dimensions, because the material, which is limestone, was secreted by the swollen collar of the worm, and being freely poured out as required, was moulded of the proper calibre by the rotatory motion of the animal, combined with the special use of certain tactile organs for the purpose. The shelly tubes themselves afford us ocular evidence not only of their progressive formation, but also of the successive steps by which this was effected. For at certain intervals of their length we perceive rings of the common stony substance, which mark the rim or mouth of the tube as it existed after each periodic increase. The mouth of the tube is, as we see, slightly expanded in a trumpet fashion; but as the general cylindrical figure is to be maintained, the next deposit of calcareous matter is not made at the very edge of the lip, but on a ring a little way within the margin, whence it is carried up, leaving the former margin slightly projecting. [Illustration: SERPULA.] Who could hesitate to assert that a history of past time is legibly written in the annulations of these stony tubes? And yet the creatures, with their tubes, have been but this instant created. But here is a tube of quite another construction, though inhabited by a kindred worm. It is wholly built up of sand, the inimitable architecture of the indwelling _Terebella_, who has thus succeeded in performing a task which defied the efforts of that too industrious artizan,--the familiar of the renowned Michael Scott.[67] Our worm has certainly spun a rope of sand, and one which holds together with surprising tenacity. The instrument which our little architect wrought with are the long tentacles, which, like a tangled tuft of yellow sewing-cotton, twist and twine over the floors of sandy pools. Nothing at first sight seems less adequate for the purpose than those very slender, soft, and flexible threads. Dr. Williams shall tell us how they are used. "They consist of hollow flattened tubular filaments, furnished with strong muscular parietes. The band may be rolled longitudinally into a cylindrical form, so as to inclose a hollow cylindrical space, if the two edges of the band meet; or a semi-cylindrical space, if they only imperfectly meet. This inimitable mechanism enables each filament to take up and firmly grasp, _at any point of its length_, a molecule of sand; or, if placed in a linear series, _a row_ of molecules. But so perfect is the disposition of the muscular fibres at the extreme free end of each filament, that it is gifted with the two-fold power of acting on the sucking and on the muscular principle. When the tentacle is about to seize an object, the extremity is drawn in, in consequence of the sudden reflux of fluid in the hollow interior; by this movement a cup-shaped cavity is formed, in which the object is securely held by atmospheric pressure; this power is, however, immediately aided by the contraction of the circular muscular fibres. Such, then, are the marvellous instruments by which these peaceful worms construct their habitations."[68] Since the slender tentacles are the implements by which the sand-tube is thus built up, it is manifest that the existence of the tube must be subsequent to the existence of the tentacles. But the _Terebella_ was at one time without tentacles; so that its history certainly reaches back to a date anterior to the existence of a tube. Several stages of life have intervened between that distinguished by the present worm-form, and its infant condition, when it swam as a ciliated undivided monad. So, at least, we conclude from physiological data; but our conclusions are false, because contradicted by the fact that the mature animal with its case has been just now created. * * * * * Let us forsake the ocean-shore, and walk again through the glades of the virgin forest. A White-ant (_Termes_) crosses our path, and, by tracking him home, we speedily discover his dwelling, an enormous structure composed of gnawed wood cemented with an animal secretion, and formed into thin but very firm and hard layers. Swarms of labourers are passing in and out; and, on our breaking away a portion of the edifice, out come crowding the warriors, with formidable jaws extended widely, ready for the fight. In the interior we find numerous chambers stored with food, and nurseries occupied by young and eggs, the number of which is every hour increasing by the oviposition of the gravid female,--the queen of the city--who is lodged in an apartment in the very centre of the whole. The entire edifice has been built around her; she is the hope of the colony, the only mother in this vast assemblage. It is therefore through her that we must look for a past history; and in her we find it. Some months ago, when she was not more than one thousandth part as large as she is now, though then adult, she migrated from some other city not less populous than this is now. It was just before the periodical rains, when, at the time of the great annual swarming, myriads of winged males and females were evolved from the pupa state, and flew out from their native city. This individual female was found by some of the workers that now compose this colony, and was immediately selected to be at once their prisoner and their queen. We thus trace our great egg-laying Termes to a city of last year's building, in which for a time she was in an immature condition as a nymph, and before that passed a still less-developed stage as a larva. Hence her life-history goes yet farther back to an egg, originally laid by a former female in exactly the same circumstances as those in which we find this guarded and immured individual. Thus we reason; but the female, with her host of attendants, and the house, which is inseparable from their present stage of existence, has been created to-day. See that creature which with loud ringing hum is whirling round and round the tassel-like blossoms of this noble _Eugenia_. You would think it a bird from its massive size, but it flashes and sparkles in the sun, like a great jewel. Now it suddenly alights on one of the crimson flowers, and you may perceive that it is a beetle;--a beetle of vast size, and glittering like a lump of burnished metal;--it bears the name of Goliath,--a giant clad in polished armour. This is his first hour of existence; now for the first time has his nervous system responded to the stimulus of the sweet air and genial sunshine. An hour ago he had no nervous system; no system of any sort; no life; no being; no anything;--he was not until this hour. Yet if we were to ask a friend conversant with entomology his opinion on the age of this insect, he would immediately give it; not, however, as an opinion, for he would repudiate the uncertainty which such a word implies, but as an indubitable fact, resting on the infallible grounds of constant observation and undeviating experience. [Illustration: GOLIATH BEETLE, AND PUPA CASE.] "This fine _Goliathus_," he would say, "has not long, probably, emerged from a hollow case of oval form, made of particles of earth agglutinated together by a secretion from the mouth of the larva, and concealed under the surface of the ground. Within that sepulchre it has left its cerements,--the shrivelled skin of the pupa, in which it had been wrapped up motionless like a mummy, for several weeks prior to its appearance as a glittering beetle. The construction of the oval cell was the last act of the larva, a thick, massy, heavy-bodied grub, which had fattened for years by feeding on the roots of plants beneath the soil. Four years passed away[69] while yon beetle lay on its side, darkly labouring at this occupation; and before that it was a minute egg for some weeks. The specimen before us cannot be far short of five years old." No such thing: the witness is at fault: the _Goliathus_ is not _an hour_ old. Take notice of the swarm of Gnats, which, like a dim cloud, are uniting in choral dance and song in the beam of the setting sun. Every member of the band that "winds his shrill horn," has had an aquatic before he had an aërial existence. A week was spent, in lobster-shape, with two breathing tubes on the summit of his body, in passing alternately from the bottom to the top of yonder stagnant pool, and then back from the top to the bottom. And a month was occupied in pretty nearly the same employment, but in another mask,--in fish-like form, with the star-tipped breathing-tube projecting from the side of the tail. But for some months earlier still it was a little lenticular egg, which was agglutinated with a number of others into an oval concave boat, that floated to and fro on the surface of the pool. And there was something worth observing in that tiny skiff of eggs; for it did, in its artful construction, carry the evidence of time back to a former generation. The eggs individually and separately would have sunk to the bottom of the water; it was, however, essential to their life that they should be in contact with the air as well as with the water. Hence they were so arranged in the aggregate, that the mass should swim, though the constituent individuals could not. To effect this, the parent Gnat, resting on the calm surface of the pool, crossed her two hind legs, and laid an egg perpendicularly in the angle so made: others were added in succession, all maintaining the perpendicular position, all glued together by a cement that resists water, but so arranged, the crossed legs being still the mould, that the outline should be spindle-shaped, while the summits of the central eggs, being a little lower than those of the outer ones, gave a concavity to the boat. So buoyant was it when finished, and the mother's legs withdrawn, that even a drop of water falling full upon it from above, would have failed to submerge it. There it floated, week after week, and month after month, all through the winter, till the genial sun of spring hatched the fish-like larvæ to begin their wriggling existence beneath the surface. Now may we not say with confidence, that the sounding-winged insect looks back to the pupa, the pupa to the larva, the larva to the egg-boat? And more, that the form of the boat,--a form so essential that it could not have lived without it,--looked back to the crossed feet of the mother-gnat, the impress of whose angle its extremities sustained? Of course we might reason thus: but yet we should be at fault; for the ringing swarm of merry Gnats has been this very evening created. [Illustration: LARVA OF CASE-FLY.] The Case-flies (_Phryganea_) that look like delicate moths of sober-brown hue, flitting over the surface of the pond, have, like the Gnats, spent a considerable time under water. When they were larvæ, they industriously collected small shells, fragments of stone, bits of reed, and the like matters, and, connecting them together with strong silk, made out of them slender tubes, in which they sheltered their soft bodies from harm, while their hard polished heads and shoulders projected from the open end. And after having lived through the winter (at least, but I rather think more than _one_ winter) in this state, each closed up the entrance of his castle, by spinning across its open end, a transverse screen of lattice-work, made of very strong and stout silk, which, while it should serve the purpose of keeping out evil-minded intruders, during the helpless inaction of the pupa, should at the same time admit the free ingress and egress of water necessary for its respiration. The life of the larva, and the exercise of these, its curious instincts, are, together with the duration of the pupa stage, inseparable precedents of the imago state in which we now observe the flying insects. No, not "inseparable;" for in this case, at least, they had no existence in time; they are prochronic developments. [Illustration: MELICERTA.] In this pond at our feet there is an object worthy of a moment's observation, minute though it is, for it is only visible as a speck to the unassisted eye. On one of the whorl-filaments of this tuft of _Myriophyllum_, there stands up a cylindrical tube, firmly adherent to the plant by its foot, but free at its upper end. Small as it is, this chimney is built up of hundreds of pellets, solid, round, and yellow; placed in symmetrical order, and firmly cemented together. What has made this tube? Ha! here is the little architect ready to answer for himself; he thrusts out his head and shoulders from his chimney-top, and announces his scientific cognomen as _Melicerta ringens_. Look! he is in the very act of building now. Did you see him suddenly bow down his head and lay a brick on the top of the last course? And now he is busy making another brick; his mould is a tiny cup-shaped cavity just below his chin; his material the floating floccose atoms of vegetable refuse. Cilia along his flower-like face collect these atoms into a stream, and pour them into the cup; and cilia within the cup whirl them rapidly round and round in many rotations, until with the aid of mucus they are somewhat consolidated into a round pellet. The brick is made, and nothing remains but that it be deposited next the former, in regular progression, and this is done by the tiny [Greek: tektôn], suddenly bending his head forward, and bringing the chin-cup with exact precision to the spot. And how long has he been engaged in this piece of work? Little more than a day. It was commenced yesterday, when the creature was not more than one-third as large as he is now. But he had lived a few hours before the commencement of his work. He was a rover before he began to be a house-keeper. In that early stage of youth and freedom, before he had made up his mind to settle in life, he had no chin-cup, no flower-like face, and of course no tube. A cylindrical gelatinous pellucid worm, he issued out of the egg, with a brush of cilia on his crown, and danced waywardly through the water. While thus occupied, his form underwent some preliminary modifications, and at length was sufficiently matured, to enable him to choose a spot for the passing of his future life, and to commence the building on which he is still engaged. Not so. The pellet which he deposited when we began to look at him, was the first he had ever made; he had been created but that moment; and all the previous pellets of the case had been called into being just as we saw them. They were built up prochronically. I tear a piece of bark from the trunk of this half-decayed tree, and have disclosed amidst the rank-smelling damp and rotten wood, a large _Julus_, a slow-moving creature, with some hundred-and-fifty little twinkling feet. As this specimen has attained its adult condition, it must be at least two years old; for it does not acquire its reproductive organs and perfect development till that age.[70] This creature has passed through a rather curious history of evolutions. The egg from which it was produced was lodged in a chamber excavated by the parent, a few inches below the surface of the rotten mould. From this egg proceeded a little kidney-shaped body, without limbs or motion, completely enveloped in a swathe of delicate transparent membrane. About a fortnight it remained in this helpless state, during which its organs had been forming out of the constituent cells, by repeated subdivision, and definite arrangement. At length it burst its cerement, and a minute Julus appeared, not more than 1/200th of an inch in length, composed of a head with antennæ, and a body of eight segments, of which the first three carried each a pair of legs. All the multitudinous limbs which we see in this adult have been produced in successive moultings, and all the numerous segments have been produced by the subdivision of the last but one,--that is the joint preceding the anal one,--six at a time. By the time the little animal was ready for the second sloughing, that is, in about a week after the preceding, three more pairs of feet were seen, which had budded from the fourth, fifth, and sixth segments, but which were as yet closely packed down beneath the investing skin; the seventh segment also was obscurely marked into six divisions. The skin was now thrown off, and these changes were perfected; the little Julus now had six pairs of feet, and thirteen segments. This process was repeated again and again; the new limbs always developing on the segments last produced, and six new segments being always formed out of the existing penultimate. And by this gradual succession of development, the animal has attained the number of limbs and segments which we now perceive. The antennæ and the eyes have likewise passed through successive stages. We have a right to infer the lapse of a period sufficient to produce these changes, for we see their indubitable results; but our inference would only lead us astray, because we have not allowed for a disturbing influence,--that of the Law of Creation. This is the Julus's first hour of life. See, on the trunk of that towering _Cedrela_, a round hole, out of which a large Beetle is in the act of emerging. It is a noble _Buprestis_, encased in glittering mail, of the most refulgent metallic splendour, crimson, gold, and green. Can we find any clue to his age? Yes: the white grab has rioted and fattened in its burrows in the timber of this tree for many years; ever gnawing away with its horny auger-like jaws the solid wood in tortuous galleries, which constantly enlarged, as it progressively grew, while its wake, as it advanced, was partially filled by its ordure. The old tree is, no doubt, perforated, through and through, by its winding corridors, as large as your middle finger. As soon as the vermin had passed this his nonage, which, as I say, may have occupied a dozen years at least,[71] he sank into his short pupa-sleep, and here we see him paying his first visit to the light of day. True; this is his first experience of daylight, and indeed of anything; for all the pupa-sleep and the larva-labour were prochronic in this case. The Beetle is just created. Hark to that hollow roar! There is no mistaking that majestic sound. It is the voice of the many-sounding sea. Yonder through the trees we catch a glimpse of its shining face, and here we are at the verge of the cliffs, against whose feet the waves are breaking in white foam. We will clamber down to the rocks. In this weed-fringed tide-pool there is a fine specimen of the Shore-crab (_Carcinus moenas_). It is a male just arrived at the perfection of adult age; its carapace smooth and wholly dark-green in hue, its under parts rufous orange. Its claws. are large and sharp; and the promptitude with which it presents these formidable weapons, extended to the utmost, shows how conscious it is of its warlike powers. To all appearance this Crab is several years old;[72] I mean in this his present perfect or imago form. When this form was first assumed, the diameter of the carapace was not more than an eighth of an inch; it is now two inches; a great many periodical sloughings of the crust must have occurred to accomplish this sixteen-fold increase. But four distinct metamorphoses were passed before the commencement of this form. There was the Grapsoid form with the outline of the carapace nearly parallel-sided, and the dentations on the sides. Before this there was the Megalopa form, with the carapace ovate, and the abdomen projecting behind. Before this there was the Zoea form, with the carapace rising into a tall erect spine, sessile eyes, no claws, and the abdomen a slender jointed cord ending in a triangular plate. And before this, there was the egg, which was laid by the mother Crab, and carried by her for a considerable time attached to the false feet of her abdomen. All these evidences of age, clear and unanswerable though they are, are yet fallacious, because the Crab has been created but this morning. On this sea-washed branch of a tree, which has been blown off by some tempest, and carried into the ocean, there is a single Barnacle (_Lepas_). It consists of a hand of many pairs of fringed fingers, protected by a shell of five pieces, and a long flexible cartilaginous stalk, by the lower extremity of which it adheres to the timber. The shelly valves are all crossed by strongly marked lines running over their surfaces in a direction parallel with each other, and with the outer margins of each valve. These, like the corresponding foliations in the tube of the _Serpula_, indicate the successive stages of growth; the outlines of every valve having stood at each of these growth lines in succession. On each of the scutal valves in this individual I can count about 260 growth-lines: if we suppose one of these to be made in a week,[73] and the increase to proceed uniformly throughout the year, we must conclude the valve to have been just five years in making. [Illustration: LEPAS.] This animal, like others we have already examined, had, moreover, a history before the first vestige of a valve was formed. It had passed through several metamorphoses; in its pupa stage it had the form of a _Cypris_, and in this condition it first became adherent to the timber: before this it was a larva, having a general resemblance to another Waterflea, the _Cyclops_, especially in its younger stages: in this state it moulted several times. Nor was this the beginning of its life; for there was the still earlier condition common to all these classes of animals, viz. that of the egg, which was laid and carried for some time by the parent Barnacle, and at length hatched while within the valves of her shell. Thus, through a course of several years we are able to trace back the existence of this Cirriped, to its parent of a former generation. But our conclusions are altogether vitiated by the simple fact that this individual is the first of its species; it never had a parent; it never was an egg. From the rocky pool before us I have picked up a rough pebble, the surface of which is incrusted with a delicate work of stony lace. This fabric, too fine to be resolved by the unassisted eye, consists of the oval cells of a species of _Lepralia_. There are some hundreds of cells in this patch, which altogether does not cover a square inch of the pebble; and they are all made after one pattern, and set in a very regular manner, in quincunx. Each is a minute slipper-shaped box of stone, with the orifice set round with spines for the protection of the inmate, a transparent, elegant, and sensitive Polypide, which bears on its head a coronet of ciliated tentacles. I am not going to describe the interesting structure and economy of this atom of life; but merely wish to direct your attention to one point,--the evidence which it affords of the lapse of past time. Every one of these hundreds of stony cells, together with its living tenant, was normally produced by a process of gemmation; each having budded forth from the side of its predecessor as a knob of clear gelatinous flesh, in the midst of which was developed, first the cell, and then the polypide,--the latter appearing in a rudimentary condition, and gradually acquiring its proper organs, before the orifice of the cell was opened. I said every one of the cells was thus formed; but I ought to have excepted a single cell, which, though in nowise differing from the rest in form or structure, had a very different origin. This was the primal cell, and its beginning was as follows: A minute atom of a scarlet hue, and of a semi-elliptical shape, was one day whirling round and round with rapid gyrations in the open sea. It was of soft consistence, covered with strongly vibrating cilia, and furnished with some stouter setæ. After enjoying its motile instincts awhile, it settled down on this pebble, and became stationary. Presently it secreted and deposited calcareous matter around at, like a coating of the thinnest glass, the red parenchyma receding from the hyaline wall towards the centre. Soon an orifice with thickened edges appeared on the upper side, and minute spines grew from the edges, which quickly lengthened. It was now a _Lepralia_ cell, and now the polypide was developed, and protruded its mouth from the orifice, surrounded by its elegant bell of ciliate tentacles. This solitary cell became the parent of hundreds more, by the gemmative process which I have already described. But the red swimming atom;--whence came that? Well, it was shot out from the interior of a previous _Lepralia_, the result not of a gemmative but of a generative act. It originated in another patch similar to the one which incrusts this pebble, and that, in like manner, and by exactly similar stages, looked back to an anterior patch, and so on. Plausible as this inference is, it is false; for the little aggregation of cells and polypides has been called into existence by the Divine _fiat_, this very instant. We are still at the sea-shore. Within the long and narrow crevices into which these low-lying ledges of shale are split, innumerable tufts of sea-weed,--olive, purple, and green,--are perpetually waving in the wash of the sea. On one of these branching shrubs of _Phyllophora_, there is adhering, apparently cast there by accident, an irregular mass of pellucid jelly. It firmly cleaves to the alga, enclosing the bases of several branches within its firm but gelatinous substance. This knob of jelly is a compound animal of the genus _Botryllus_, and it has just been created as we see it. In order to understand its nature, look at it more closely. Enclosed in the clear purplish-grey jelly, in the midst of scattered lighter specks, we see several star-like figures of bright hues, in which yellow and red are predominant; the symmetrical arrangement of which pleases the eye, and reminds us of some ornamental pattern designed by human art. Each star is composed of several (three, seven, ten or more) pear-shaped animals, with their smaller ends meeting in the centre around a common orifice, from which a current of water is discharged. Now this assemblage of animals bears evidence of progressive development. Some time ago a tiny egg was discharged from a parent _Botryllus_, which presently produced a little active tadpole-like larva, called a "spinule." This swam actively by means of its wriggling tail; but at length it settled head downward on this piece of sea-weed. Immediately the head adhered, by an effused cement, to its support; the tail now gradually disappeared; and the round head, in the midst of a mass of jelly-like cement, began to display two orifices on its surface. It soon assumed a pear-like shape, and thus the first _Botryllus_ was formed. From the side of this "pear," another was developed by gemmation, and a third on the opposite side; the smaller ends of all were in contact, and the orifices of these extremities began to merge into one; while the large ends diverged. A fourth and a fifth "pear" were successively produced in the same mode, until a star or "system" was formed. Meanwhile the surrounding mass of living jelly had been commensurately enlarging, and a new _Botryllus_, separate from the other star, had been produced in the jelly, which was the commencing point of a second system; and thus, by degrees, the compound mass of systems has grown to its present state of development. [Illustration: BOTRYLLUS. _a_, portion of one system and of a mass, on _Phyllophora rubens_; _b_, an egg _c_, spinule; _d_, the same, attached; _e_, the tail absorbed; _f_, the young _Botryllus_. All magnified.] This process has been one of time: the adhesion of the "spinule" took place in about sixteen hours after its escape from the egg. The appearance of the two orifices was when the little animal was four days old; and by the end of a week a second "pear" had budded. The attainment of the present condition may have occupied about six months. Nay; time has been no element in this development; it is prochronic development; it is the development of creation, not of nature. Behold that ruffling of the smooth surface of the water; it is caused evidently by the forcible ejection of a current from some source a little way beneath the surface. Yes, it proceeds from the orifice in this mass of calcareous grit; where the protruding pipe of shell indicates the snug fortress of a _Clavagella_. I will carefully break away a little of the soft stone, and we shall see the curious structure more clearly. Ha! I have split off a piece which nicely exposes the whole burrow, without having materially injured the creature or his shell. You see it is a bivalve Mollusk with one valve firmly imbedded and cemented into the stony wall of its chamber. But the hinder end of this valve is continued into a shelly tube, intended to protect the siphons, which is carried through the gallery forming the entrance into the chamber, and opens by a wide orifice in the free water outside. It is to this tube that I call your attention. [Illustration: CLAVAGELLA.] You observe that on its outer surface there are several foliated expansions of the shelly substance, surrounding it like so many frills at pretty regular intervals. Each of these foliations is a permanent record of a certain epoch. The terminal one is the margin of the tube-wall everted. The one below this was at some past period the eversion of the margin at what was at that time the extremity. The third frill had in like manner terminated the tube still earlier; and so with the fourth and fifth. It is impossible to look at these expansions, and not to believe that they have been formed in succession, in this way, by the periodic growth of the tube. There was a time when, the first frill was not commenced; when the creature was a Mollusk with simple valves. But even this was not the beginning of its history. It was as a swimming Infusory with a broad ciliated disk, and a lashing _flagellum_, that the creature commenced its independent career; and it was doubtless in this condition[74] that it found its way into the burrow of some _Saxicava_. Here its tiny transparent valves were secreted; the left valve was soon cemented to the chamber; and then the creature began to secrete and form the tube around its siphons, which was progressively enlarged, and adorned at every stage of elongation by these witnessing frills--whose testimony is recorded in imperishable stone. What can be more irresistible than such evidence as this? And yet we must take exception to it on the ground that this is the very hour of the animal's creation. [Illustration: DIONE VENERIS.] The elegant spinous shell-fish that we discern yonder, half-buried in the sandy floor of the sea--I mean that lilac-tinted Prickly Venus (_Dione Veneris_) needs no shelly protection for its siphons, which, as you may observe, are protruded to a great length. But a lesson not less instructive than that taught by the tube-frills of the _Clavagella_, is inculcated by the valves of the _Dione_. Near the hinder margin of each valve there is a ridge which runs from the beak to the front edge, a ridge which bears the series of long slender shelly spines, that imparts such a charm to this shell. Each of these spines records an interval in the growth of the shell. There are sixteen distinctly enumerable; each of which may possibly mark a year's growth. The increase of bivalves, however, is slow; and it may be that a longer interval than a year has intervened between spine and spine. For if we look more closely at this beautiful shell, we see that the whole exterior of both valves is marked with concentric foliated ridges, which are also indubitable lines of growth; and that these are twice or thrice as numerous as the spines, from one to five being intercalated between those which support the prolongations of the shelly substance. Each of these concentric lines has a history. Every line, as well as every spine, has been produced by a protrusion and eversion of the glanduligerous edge of the mantle, which then secreted and poured out a copious deposit of calcareous matter along the margin of the previously existing valve. In this species each periodic deposit took the form of a ridge slightly elevated above the general surface; and, because the turned up margin of the mantle invested the edge of the valve already formed, therefore the new layer, with its elevated ridge, was concentric with the last edge, which was concentric with the previous one, and so on, the common centre of all being the beak (_umbo_) at the back of the valve. The spines were formed in a manner essentially similar. At every second or third period of increase, the margin of the mantle, which is very versatile and protrusile, was thrust out, at the point which corresponds to the spines, into a long fleshy groove, by the reduplication of its edge. Within this groove the calcareous secretion was poured out; and after it had been allowed a few moments to harden or "_set_," the mantle-groove was cautiously withdrawn, and a new spine was exposed, as a produced end to the foliated ridge. Yet, though this is the normal and natural mode of production, both of the concentric line and of the spines, it would be illusory to conclude that they have been so produced in the present example. The entire formation of the _Dione_ before us has been ab-normal and preter-natural: it has been _created_, not _born_: the whole development so legibly written on the shell has been prochronic. There goes the Scorpion Stromb (_Pteroceras scorpio_), crawling over the rocks with protruded head and tentacles, and bearing his massive house on his back. This shelly house of his will afford us a good example of structural development. The great dilated lip, and the long finger-like processes of its edge, had no existence in the youthful days of the shell; they are marks of adult age: when young, the shell was simply spiral, with a thin straight lip bounding a narrow aperture. Observe also a far more beautiful creature by its side, the Tiger Cowry (_Cypræa tigris_). Its shell is now entirely enveloped in the meeting wings of the great fleshy mantle, which is mottled with changing hues; and its foot or crawling disk covers a space three or four times as large as the shell. On lifting it in our hand, the whole of this array of soft flesh has been rapidly retracted, and has wholly disappeared within that very narrow orifice, bordered with toothed projections, on the under side of the shell, which we can hardly believe capable of receiving a twentieth part of the bulk that has vanished within it. And now we see nothing but the shell, with its smooth rounded back, marked with dark spots, its white inferior surface cleft by this longitudinal denticulate aperture, and its brilliant porcellanous varnish over the whole. Now here is evidence of change and progress again. This Cowry-shell is very unlike that of an Olive, with a simple spire, an oval body, a smooth thin lip, and a wide orifice; and as unlike that of a Nautilus. Yet it has passed through both of these stages before it was disguised as we see it now. When it escaped from the egg-shell, it was a minute Pteropod, with two great ciliated disks, inhabiting a transparent nautiloid shell, and swimming giddily about in a revolving fashion. By and by, the tiny shell increased, and the outer whorl lengthened, putting on a long-oval figure. Then--that is, after a considerable period occupied in increasing the dimensions of the shell in this form--it began to assume the adult appearance. The outer lip, which had hitherto been thin, gradually thickened and encroached upon the spire, and the mantle began to secrete and deposit on the outer surface the coat of glassy enamel. At length the thickening of the lips proceeded to such an extent as almost to conceal the spire, and to reduce the aperture to a narrow line, the edges of which were now thickly plaited with the tooth-like ridges so characteristic of the genus. The lobes of the mantle now protrude through this aperture; and, expanding on each side, have deposited all over the exterior of the shell a coat of glassy enamel, studded with dark round spots or clouds, which entirely conceals the surface with the markings that were formerly visible upon it. [Illustration: MUREX TENUISPINA.] Yonder Thorny Woodcock (_Murex tenuispina_) is a still more striking shell than either, and one whose periodic growths are peculiarly well marked. It is covered at regular intervals with rows of shelly spines, still longer and more numerous than those we lately admired in the _Dione_. Each series crowns a thickened ridge, which runs across the whorl, as regards the direction of its growth, but longitudinally as regards the general figure of the shell. Now, the increase of the shell in the Univalves is performed almost exactly as in the Bivalves; namely, by the protrusion and eversion of the mantle on the existing edge. And, therefore, each of these thorny ridges, separated as they are by an interval of just two-thirds of a whorl, marks the termination of a new growth, the shelly matter rising up at the margin in this thickened ridge, which bristles with elongated points. In this specimen we can trace ten such ridges, whence we legitimately infer ten distinct periods through which this animal has passed, besides the nautiloid stage under which all the creatures of this Class commence existence. Yet, since each of these three univalves has been this day created, these inferences are deceptive. The Scorpion-shell was _never_ otherwise than dilated and digitated. The Cowry has _never_ had a lip that was not thickened, nor an exterior that was not porcellanous. The Woodcock has _never_ known a moment in which its thorns were less numerous than they are now. Notice that fine round shell carried along the floor of the sea, by means of a great fleshy tortoiseshell-coloured[75] body, which, with a head of many spreading tentacles applied to the ground, crawls with a tolerably quick progress.[76] It is the Pearly Nautilus. The amplitude of the beautiful nacreous shell is by no means a measure of the dimensions of the animal; for this merely sits within the shallow mouth, like a Welsh fisherman in his coracle. If we remove the creature, we shall find the cavity bounded by a pearly floor, in the centre of which is a slender tube running down from it. On breaking away this floor, we expose an empty chamber, with a similar pearly floor, through which passes the shelly tube, continued through the middle of the chamber, and running down to the next. Thus we should find the whole interior of the shell occupied by a series of these empty chambers, fifty or upwards in number, each less than its predecessor (rather _successor_, if we regard them in the order of development), until we can trace them no longer in the minute centre of the spire. Without dwelling on the function of these chambers, farther than to say that they appear admirably contrived to make the animal with its shell either heavier or lighter than the surrounding fluid, by forcing water into them through the tube, and thus condensing the contained air, or by relaxing the pressure, and allowing the elasticity of the air to exclude the water,--our business is just with the formation of the septa, as an evidence of periodic development.[77] "The septa are formed periodically, but it must not be supposed that the shell-muscles ever become detached, or that the animal moves the distance of a chamber all at once. It is most likely that the _adductors_ grow only in front, and that a constant waste takes place behind, so that they are always moving onward, except when a new septum is to be formed; the _septa_ indicate periodic _rests_."[78] These periodic alternations of rest and action, however, it is obvious, can never have really existed in an organism which has but this instant been created. The appearances, therefore, which indicate them, are illusory, considered as testimonies to actual time. You are aware that what is often spoke of as the "bone" in this Cuttlefish (_Sepia officinalis_), is only a concealed shell; and I need not to dissect the animal to acquaint you that it is a highly interesting structure. A deservedly eminent physiologist shall describe it for us. "The outer shelly portion of this body consists of horny layers, alternating with calcified layers, in which last may be seen a hexagonal arrangement. The soft, friable substance, that occupies the hollow of this boat-shaped shell, is formed of a number of delicate plates, running across it from one side to the other in parallel directions, but separated by intervals several times wider than the thickness of the plates; and these intervals are in great part filled up by what appear to be fibres, or slender pillars, passing from one plate or floor to another. A more careful examination shows, however, that instead of a large number of detached pillars, there exists a comparatively small number of very thin, sinuous laminæ, which pass from one surface to the other, winding and doubling upon themselves, so that each lamina occupies a considerable space. Their precise arrangement is best seen by examining the parallel plates, after the sinuous laminæ have been detached from them; the lines of junction being distinctly indicated upon these. By this arrangement, each layer is most effectually supported by those with which it is connected above and below; and the sinuosity of the thin intervening laminæ, answering exactly the same purpose as the "corrugation" given to iron plates for the sake of diminishing their flexibility, adds greatly to the strength of this curious texture, which is at the same time lightened by the large amount of space between the parallel plates that intervenes between the sinuosities of the laminæ."[79] Now the delicately thin calcareous plates have all been formed in succession, "the first formed being at the outer part and posterior termination of the shell, and the succeeding new layers extending always more forwards than the edges of the old."[80] They exhibit then many hundreds of distinct deposits, each the result of a separate process, each the work of a definite period of time. The "cuttle-bone" is an autographic record, indubitably genuine, of the Cuttlefish's history. Yes, it is certainly genuine; it is as certainly autographic: but it is _not true_. That Cuttle has been this day created. IX. PARALLELS AND PRECEDENTS. (_Vertebrate Animals._) "The organisation of the body at each epoch may be truly said to be the _resultant_ of all the material changes which it has undergone during the preceding periods."--_Dr. Carpenter; Human Physiology_, p. 903. The _Invertebrata_ then agree in one story, and that story is the same as what the plants had told us before. Let us try if the Vertebrate creatures bear them out. From this promontory we can look far down into the clear profundity of the still and smooth sea. What is that large object that plays hither and thither yonder, now shooting ahead, now resting on his oars, now turning on his course, now cutting the surface, now descending to the depths? It is a full-grown Sword-fish, some ten feet long. We are sufficiently near him to discern that he has one short but high dorsal fin, near the head, and a minute one close to the caudal, the whole intermediate region being smooth. But this is a mark of adult age; for in early life this same species is furnished with one long and high dorsal, which is continuous from the occiput to the vicinity of the tail-fin. The remotely divided dorsal here tells of many years of life; but tells deceitfully, for the Sword-fish is but just created. Ha! the Sword-fish has darted away, like lightning, after a finny victim. See with what doublings and windings he pursues it, and how the terrified prey uses all its powers to escape from its gigantic enemy! Now they near the shore; and now the frightened quarry has leaped out of the sea upon yonder flat shelf of rock, where it lies gasping and floundering, delivered indeed from its pursuer, but only to die by being drowned _in the air_. We will descend from the cliffs, and look at it. It is a Gilt-head (_Chrysophrys aurata_). Life is extinct now; but the brilliant colours and fine metallic reflections are scarcely dimmed--the silvery belly--the azure fins--the sides that gleam like polished steel, inlaid with bands of burnished gold! I will pluck a scale from this brilliant silvery surface. Its hinder, or free edge, is beset with fine flexible crystalline points, arranged in many successive rows, overlapping each other. The front, or attached edge, is cut in a scolloped pattern, the extremities of undulations that radiate from a common point behind the centre. The whole surface, except the hinder portion that is studded with imbricated points, is covered with an immense multitude of fine concentric lines, which follow the form of the general outline. These are marks of successive increase; for every one of the lines is the margin of a lamina, the aggregation of which makes up the thickness of the scale. The laminæ can be separated by long maceration in water; and then we see that they are laid one on another in regular order, the uppermost being the smallest, and the first formed; the last made, which is the largest, being now in contact with the skin. [Illustration: SCALE OF GILTHEAD.] Every scale is therefore a document, on which is indelibly written the record of a multitude of processes, all effected in the past history of the fish. The successively deposited laminæ are exactly analogous to those of calcareous substance in the shell of the bivalve;[81] and the evidence is of exactly the same character as what we lately read off from the valve of the _Dione_. But, just as in that example, too, the overruling fact of recent creation precludes our deduction of time from the evidence, since it proves the development to have been prochronic. I see yonder a more terrific tyrant of the sea than the Sword-fish. It is the grisly Shark (_Carcharodon_). How stealthily he glides along, cutting the glittering surface of the sea with his dorsal, and now and then protruding just the tip of the upper lobe of his caudal in the wake of the other! Let us go and look into his mouth; for neither animals nor elements present any impediments to these investigations of ours. Is not this an awful array of knives and lancets? Is not this a case of surgical instruments enough to make you shudder? What would be the amputation of your leg to this row of triangular scalpels, each an inch and a half in diameter? moved, too, by these powerful muscles? But observe the arrangement of these most formidable teeth. They are not confined to a single row as ours are, but each is succeeded by another lying behind it, that by another, and another, and another,--why, there are a dozen ranks of teeth, lying regularly packed one behind the other. The object of this arrangement is a constant supply of new teeth, as those in use become broken off, or wasted by the sloughing away of the exterior half-ossified crust of the cartilaginous jaw, to which their base is fastened by ligaments. Only one row, the outer one, is in use at once, and this row stands erect; the others lie flat on each other (more and more completely as they recede from the outer row); a reserve of weapons in readiness for use, when those now employed are done with. There is a continual growth of the surface to which the teeth are fastened, from within outwards; so that each of the reserve rows will in turn be brought to the edge of the jaw, when it will be thrown up into the erect position, while the preceding, now turned out of the mouth by the gradual eversion of the surface, sloughs away and disappears as an useless incumbrance. It follows, therefore, that the teeth which we now see erect and threatening, are the successors of former ones that have passed away, and that they were once dormant like those we see behind them. But perhaps you may say, What evidence is there that these ever had any predecessors? that they were not originally the front rank as they are now? A very fair question. In the first place, the great size of the tooth indicates maturity; and is in keeping with the dimensions of the animal,--some twenty feet or so,--which are those of an adult, if not a full-grown individual. But adult age implies previous youth and infancy, and a gradual growth from the length of a few inches to this formidable size. The teeth are found in the embryo Shark when not more than a foot long; and it is evident that many successive generations of teeth have passed away between those pristine lancets of a line in diameter, and these of an inch and a half. But stay; there is a peculiarity in the structure of these present teeth, which surely indicates their place to be far on in the succession. Each is seen to be finely serrated on its two outer edges,--a provision which, of course, makes them more effective dividers of flesh and bone. But this structure is not found in the teeth of young individuals, which up to a period comparatively advanced, have simply cutting edges. Hence we are compelled by the phenomena to infer a long past existence to this animal, which yet has been called into being within an hour. On yonder twig sits a beautiful little Tree-frog, which you would be ready to mistake for a leaf of more than usually emerald hue, but for the glittering eye, and the line of yellow edged with purple that passes down the side. Do you notice the frequent gulpings of the throat? Those are the periodic inspirations Of air, by which the creature breathes; for, having no ribs, by means of which to depress, and so to expand, the thoracic cavity, the Frog swallows the air by a voluntary action. These air-gulps afford us another example of the sort of evidence we are searching for; they are so many proofs of a past history. For the Tree-frog has not _always_ swallowed air; there was a period in its life when it had no lungs; when it was an aquatic animal, as exclusively a water-breather as any fish. Fish-like in _form_ it was then, as well as in _habit_; it was a tadpole with a long compressed muscular tail, and with external gills of several branches, but as destitute of lungs as it was of limbs. Any physiologist, looking at our little green Tree-frog, would pronounce without hesitation on the stages through which it has passed; and would describe with the most perfect confidence the order in which they took place; the gradual absorption of the branchiæ, the development of the lungs, the shrinking up and final disappearance of the tail, the budding forth of the tiny rudimentary limbs, the hinder pair first, then the fore pair, and the subsequent division of their extremities into toes;--the metamorphosis of the little fish into a little batrachian, and the gradual growth and maturation of the latter,--these are facts,--the physiologist would say,--as sure both as to their actuality and as to their order, as that the Frog is a Frog. Ah! but the physiologist is not aware of a fact, which invalidates all his conclusions based upon experience,--the fact that the little Tree-frog has been created but this very instant. Hark! that rattling noise is an admonition to us to tread circumspectly. It is the vibration of the horny caudal appendages of a Rattlesnake. And I see the reptile coiled up under yonder shadowing leaf. But our presence is a privileged presence, and so we may handle and examine him with impunity. The organ which produces this sound is composed of a number of hollow horny capsules, each one fitting into the next, in which it is retained loosely by a protuberance of its surface. These, being agitated at the will of the animal, produce that sound which we just now heard. The capsules are developed periodically, one being added to the number already existing every year, until as many as forty are accumulated.[82] This individual, therefore, having five-and-twenty rattles, must be five-and-twenty years old. This Snake, however, has had no past years; it has had no yesterday. Its existence commenced this hour. Here crouches, among the thick reeds, the Leviathan of the rivers, the mailed Crocodile. His body, invested with bony ridged plates, that rise into strong serrations along the tail, seems clothed with power; and his long rows of interlocking teeth, unveiled by lips, appear grinning with perpetual rage. An experienced herpetologist would not fail to find many evidences of age in this huge reptile. First of all, he would point to its monstrous size; then to the breadth and massive thickness of the dermal plates. "The head," he would say, "in the ruggedness of its surface, shows the same thing, for in youth it was comparatively smooth; and also in the form of its outline; for in this example its length is double its breadth, whereas in youth, these measurements were nearly equal. These conical teeth, too, are by no means the same individual teeth which existed at first. If you look at the base of one, you will see that it is hollow, and that the sides of this portion are already in process of absorption; that this hollow cone is a sheath for another tooth beneath, which is destined to replace it; as this has itself replaced its predecessor. The large size of the teeth which we see, therefore, which accords with the dimensions of the jaws, is not a condition induced by gradual growth, but by a succession of sloughings and replacements; and hence the present teeth, in their size, point conclusively to others which have preceded them, but which have disappeared." Yet nothing can be more certain, than that, in this Crocodile, which has been created to-day, the successive teeth thus witnessed to, are but ideal, that is prochronic, teeth; and that all the other indications of the lapse of time, in the development of this individual, are liable to the same exception. See this solemn, slow-going Tortoise, shut up in his high-domed house of bones. It is the beautiful _Testudo pardalis_, well named from the plates being elegantly spotted and splashed with black on a pale-yellow ground, like the fur of the panther. This is a rather large individual, and the number of concentric lines on the plates of his armour,--or may I not rather say the _tiles_ wherewith his house is roofed?--is commensurately great. You see what I mean. Each of the angular plates has a small nuclear lamina, not in the centre of the area, for the development has been one-sided, but on the highest part. This was the plate in its earliest form, or at least the earliest of which any trace is left; for probably there were others yet earlier and smaller, which, on account of their thinness, have been rubbed away in the travels of the old wanderer. From this nucleus, the plate has been successively enlarged, to correspond with the general growth of the animal, by repeated additions of new laminæ to the inferior surface; each new lamina being a little wider in every direction than that which preceded it, though not _equally_ on all the margins; and thus the plates assumed the form of a very low cone, as you see, always preserving the specific outline, and manifesting the stages of increase, by the projecting edges of the successive laminæ, exactly as we saw lately in the scales of the fish. [Illustration: PLATES OF TORTOISE.] Whether these laminæ are increased in an annual ratio, I am not sure, nor is it important. There are, I find, about forty-five concentric lines on one plate in this specimen, besides others which are evanescent. Hence it would be quite legitimate to infer that this Tortoise has passed through at least forty-five distinct periods of life, each of which has left a legible record of its existence. And yet, this moment, in which we look at it, is the very first moment of its life; the concentric layers are evidences of processes that never occurred, except prochronically. See yonder stately bird, nearly of the height of man, marching among the luxuriant musa-groves, and feeding on the succulent fruits. There is nothing very admirable in its coarse, black, hair-like plumage; but the rich hues of its naked neck, azure, purple, and scarlet, of the most vivid intensity, attract the gaze. The most remarkable feature in its physiognomy, is the singular, tall ridge of horn on its head, which, like the crested helmet of some mailed warrior, imparts an air of martial prowess to the bird, little in accordance with its peaceful habits. This protuberance is altogether a development of age. The skull, in the youth of the Cassowary, was scarcely more elevated than that of a chicken; but in the lapse of years, the bony ridge, encased in horn, has gradually elevated itself to the height which it now possesses. Here again we have a record of time, which is belied by the fact of the bird's recent creation. What is the glorious train of the Peacock, all filled with eyes, but a false witness of the same kind? It leads us to infer that the bird is three years old at least, since before that period, the covert feathers, which are to form the splendid ornament of maturity, are not developed. What are the lengthened tail-plumes of most refulgent blue, that adorn the Fork-tailed Humming-bird (_Trochilus forficatus_); what the gorgeously golden tail of the Resplendent Trogon; what the elegant lyre-shaped feathers of the Menura; what the lustrous plumage of the Birds of Paradise,--all of which have been but this hour created,--but so many testimonies, unworthy of confidence, to a past history? But, further, every individual feather of this beautiful array of plumage concurs in bearing its unblushing witness to the same untruth. What says the physiologist, who is able to read off these autographic records? [Illustration: GROWTH OF A FEATHER.] "A little while ago, the tips of these feathers were seen each protruding from the extremity of a thick, opaque tube; and a little while before that, the tube itself, was a closed capsule, imbedded in a deep follicle of the skin. If you had then cut open the capsule, you would have found two concentric membranous tubes investing a highly vascular secreting pulp, abundantly supplied with nerves and blood-vessels through an orifice at the bottom of the capsule, and destined to form the substance of the coming feather. Indeed, you would have seen the soft, newly-formed barbs folded round the central organized matrix; and below, the incipient quill, filled with the living pulp-cells, and their blood-vessels, which were destined subsequently to wither up and collapse into the light skinny pith which you see in the perfectly matured feather. These are stages which each of these hundreds of feathers has passed through; and these are but a single generation, which have replaced former series that have been lost in the process of moulting, every one of which had in its turn passed through exactly corresponding stages, and so on backward, till we reach the first race of feathers, which were already partly developed when the chick burst forth from its imprisoning egg-shell." So says the physiologist; but is he not most egregiously in error, since this is the day of these lovely beings' creation? There goes the great Whale, the true Whalebone Whale, rolling and wallowing in the trough of the sea, and exposing his enormous black back like an island amidst the white foam, which he stirs up, "making the deep to be hoary." We will use our privilege and take a peep into his mouth, as we did just now into that of the Shark. What a cavern! and all bristling with long black hair! Why it seems as if the hair grew on the wrong side of his head--on the inside instead of the outside! Nay, what you call hair is really the Whale's teeth, or what represents teeth. This is the interior free fibrous margin of the _baleen_, which descends in long triangular plates from the upper jaw. There are about two hundred plates on each side, set face to face, with an interval between, and the edges outward. The inward edge runs off into those long hair-like filaments, which also extend from the slender tip. And the whole forms an effective sifting apparatus, by which the volume of sea-water, which the huge creature takes into his mouth in feeding, is drained of the sea-blubbers, the worms, the mollusks, and other small matters, which constitute the subsistence of this vast body. Now each of these four hundred plates, some twelve feet in length, has grown from a minute sort of bud, in the upper jaw. Its base is hollow, resting on the formative pulp which is developed from the gum. The pulp is understood to be the immediate origin of the hairy fringe, while a dense vascular substance, seated between the bases of the plates, forms the plate itself. When the plate reaches a certain length, its diameter has become greatly attenuated, and its tip is constantly breaking away, leaving the hair projecting. There is therefore a continual disappearance of the substance of the plates at the tips, and a continual growth at the base to supply the deficiency; and even more, at least during the period of adolescence, because the actual dimensions of the plates have to be increased in the ratio of the growth of the whole animal. Here, again, we read a record of past history. The Whale is known to be a long-lived animal; and a period of many years must have passed in bringing these plates of baleen to their present maturity. Yet the vast organism before us has been created in its vastness but to-day. On the most prominent shelf of yonder precipice, a sharp buttress of naked limestone, stands an Ibex, guarding, like a watchful sentinel, the herd in the sheltered valley which own his leadership. The pair of noble horns, which are at once his defence and his pride, are marked throughout their ample curve with semi-rings, or knobs, on their anterior side. These afford us an infallible criterion of the animal's age. We can count in this Ibex fourteen of such prominent bosses. Now the horn in these animals is not shed during life, but consists of a persistent sheath of horny substance, enveloping a bony core. Until full adult age, both the core of bone and the sheath of horn are continually growing; and in the spring, when there is an unusual augmentation of vital energy in the system, the increase is more than usually rapid. At this season, the new matter deposited in the corneous sheath accumulates in the form of one of these bosses, each of which is therefore produced at the interval of a year. As the first boss appears in the second year of the animal's age, we have but to add one to the number of the bosses on each horn, and we have the number of years which it has lived. The Ibex before us is just fifteen years old. [Illustration: HORNS OF STAG; In their successive developments.] Yon Stag that is rubbing his branchy honours against a tree in the glade,--can we apply the same criterion to him? Not exactly: for the horns of all the Deer-tribe are of a different structure from those of the _Capradæ_. They are bones of great solidity, not invested with any corneous sheath, but clothed for a certain portion of their duration with a living vascular skin, and are shed every year during life and as constantly renewed. Yet the bony horns of the Stag are no less sure a criterion of age, at least up to a certain period--than are those of the hollow-horned Ibex. In the spring of the second year of the Fawn, the horns first appear, seated on bony footstalks that spring from the frontal bone. The skin that covers these knobs begins to swell and to become turgid with blood supplied by enlarging arteries. Layers of bone are now deposited, particle by particle, on the footstalks, with surprising rapidity, producing the budding horns, which grow day by day, still covered by the skin, which grows also in a corresponding ratio. This goes on till a simple rod of bone is formed, without any branches. When this is complete, the course of the arteries that supplied the skin is cut off by fresh osseous particles deposited in a thick ring around the base. The enveloping skin then dies, and is soon rubbed off. After a few months, the connexion of the now dead bone with the living is dissolved by absorption, and the horns fall off. The next spring they are renewed again, but now with a branch or antler; and the whole falls again in autumn. Every spring sees them renewed, but always with an increase of development; and this increase is definite and well-known; so that the age of a Stag, at least of one in the vigour of life, can be readily and certainly stated. For example, the individual Stag before us, now browsing so peacefully, has each horn composed of the following elements:--the beam, or main stem; two brow-antlers; one stem-antler, and a coronet of four snags, or royal-antlers, at the summit. This condition is peculiar to the seventh development, to which if we add one year for the hornless stage of fawnhood, we obtain eight years, as, beyond all doubt, the age of this Stag. Both of these examples, however, the Ibex and the Stag, though so conclusive, and seemingly so irrefragable, are rendered nugatory by the opposing fact of a just recent creation. See this Horse, a newly created, really wild Horse, "Wild as the wild deer, and untaught, With spur and bridle undefiled,"-- his sleek coat of a dun mouse-colour, with a black stripe running down his back, and with a full black mane and tail. He has a wild spiteful glance; and his eye, and his lips now and then drawn back displaying his teeth, indicate no very amiable temper. Still, we want to look at those teeth of his. Please to moderate your rancour, generous Dobbin, and let us make an inspection of their condition! Now notice these peculiarities. The third pair of permanent incisors have appeared, and have attained the same level as their fellows; all are marked with a central hollow on the crown, the middle pair faintly: the canines have acquired considerable size; they present a regularly-convex surface outwardly, without any marks of grooving on the sides; their inner side is concave; their edges sharp; the third permanent molar has displaced its predecessor of the milk set, and the sixth is developed.[83] This condition of the teeth infallibly marks the fifth year of the Horse's age. A year ago the third incisor was only just rising; the canines were small, and strongly grooved, and the third milk grinder was yet existing. A year hence, the central incisors will be worn quite flat, and their marks obliterated; the canines will be fully grown tusks, the second molar will have reached its full height, and all the teeth will be of the same level. We can then with perfect confidence assert this to be a five-year old Horse. And yet, if we do so, we shall assert a palpable untruth, for the young and vigorous stallion has been created to-day. [Illustration: SKULL OF BABIROUSSA.] In the thickets of this nutmeg grove beside us there is a Babiroussa; let us examine him. Here he is, almost submerged in this tepid pool. Gentle swine with the circular tusk, please to open your pretty mouth! Here are four incisors in the upper jaw; _at one time there were six_. The canines of the same jaw having pierced through the flesh and skin of the face, have grown upward and curved backward like horns; nay, they have nearly completed a circle, and are threatening to re-enter the skull; _once these tusks had not broken from the gums_. There are two pre-molars: _once there were four_. There are three molars, of which the first is worn quite smooth: _once this surface was crowned with four cones; but the third molar had not then appeared_. Away to a broader river. Here wallows and riots the huge Hippopotamus. What can we make of his dentition? A strange array of teeth, indeed, is here; as uncouth and hideous a set as you may hope to see. Yes, but the group is instructive. We will take them in detail. Look at the lower jaw first. Here are two large projecting incisors in the middle, with their tips worn away obliquely on the outer side, by the action of their opponents in the upper jaw, which are also worn inwardly. The outer incisors, both above and below, are also mutually worn in like manner. The lower canines form massive tusks, curved in the arc of a circle, ground away obliquely by the upper pair; which are short and similarly worn on their front edges. There are three pre-molars on each side, below and above, much worn: once there was a fourth, but it was shed early. Lastly, we find three molars, whose crowns are ground down so as to expose two polished areas of a four-lobed figure. A little while ago, these double areas were trilobate, but at first there were no smooth areas at all; for these are but sections, more or less advanced, of the conical knobs, with which the crown of the molar was originally armed.[84] In both these examples, the polished surfaces of the teeth, worn away by mutual action, afford striking evidence of the lapse of time. Some one may possibly object, however, to this: "What right have you to assume that these teeth were worn away at the moment of its creation, admitting the animal to have been created adult? May they not have been entire?" I reply, Impossible: the Hippopotamus's teeth would have been perfectly useless to him, except in the ground-down condition: nay, the unworn canines would have effectually prevented his jaws from closing, necessitating the keeping of the mouth wide open until the attrition was performed; long before which, of course, he would have starved. In a natural condition the mutual wearing begins as soon as the surface of the teeth come into contact with each other; that is, as soon as they have acquired a development which constitutes them fit for use. The degree of attrition is merely a question of time. There is no period that can be named, supposing the existence of the perfected teeth at all, in which the evidence of this action would not be visible. How distinct an evidence of past action, and yet, in the case of the created individual, how illusory! [Illustration: SKULL OF HIPPOPOTAMUS.] "Trampling his path through wood and brake, And canes, which, crackling, fall before his way, And tassel-grass, whose silvery feathers play O'ertopping the young trees,-- On comes the Elephant, to slake His thirst at noon, in yon pellucid springs. Lo! from his trunk upturn'd, aloft he flings The grateful shower: and now Plucking the broad-leaf'd bough Of yonder plane, with waving motion slow, Fanning the languid air, He waves it to and fro." We will not be content with admiring the vast size of the fine Dauntelah, and the majesty of his air and movement, and the intelligence manifested in all the actions of the "half-reasoning" beast, as he explores the amoenities of the young world to which he has but this morning been introduced. We are out on another sort of scent: let us try if we can glean any light from him on our present question. And, first, we cannot fail to notice his fine pair of tusks curving upwards almost to a semicircle. Each tusk is composed of a vast number of thin cones of ivory, superimposed one on another; ever increasing by new ones formed within the interior at the base, and moulded upon the vascular pulp which fills the cavity, and by which the solid ivory is constantly secreted and deposited. Each new cone pushes further and further out those previously deposited, and thus the tusk ever grows in length as it increases in age. [Illustration: SKULL OF ELEPHANT.] How many years have these tusks occupied in attaining their present diameter and length? We cannot tell: without a transverse section we cannot determine the number of layers of which each consists: and if we could, we should yet require to know what ratio exists between the deposition of a cone of ivory and a fixed period of time. The cones, however, in a tusk of these dimensions, are very numerous, for they are but thin; and it is enough for our purpose that they have occupied the same number of periods of time for their formation, though we cannot precisely indicate the length of these periods. Leaving the tusks, which are the upper incisors, let us now examine the molars. And there is in these a remarkable peculiarity of development, which will assist us greatly in our chronic inquiries. Before we look at them it may be as well to consider this peculiarity. The Elephant has, from first to last, six, or perhaps eight, molars on each side of each jaw; but there are never more than two partially, or one wholly, in use at once. They have originally an uneven surface, produced by the extremities of a number of what may be considered as so many finger-like constituent teeth, arranged in transverse rows, covered by hard enamel, and cemented together by a bony substance. These points are gradually worn down by the process of mastication, and then the compound tooth appears crossed by narrow cartouches, or long ovals of enamel, indented at their margins. "The first set of molars, [_i. e._ the first compound molar] or milk teeth, begins to cut the jaw eight or ten days after birth, and the grinders of the upper jaw appear before those of the lower one. These milk-grinders are not shed, but are gradually worn away during the time the second set are coming forward; and as soon as the body of the grinder is nearly worn away, the fangs begin to be absorbed. From the end of the second to the beginning of the sixth year, the third set come gradually forward as the jaw lengthens, not only to fill up this additional space, but also to supply the place of this second set, which are, during the same period, gradually worn away, and have their fangs absorbed. From the beginning of the sixth to the end of the ninth year, the fourth set of grinders come forward to supply the gradual waste of the third set. In this manner to the end of life, the Elephant obtains a set of new teeth, as the old ones become unfit for the mastication of its food. "The milk-grinders consist each of four teeth, or _laminæ_; the second set of grinders of eight or nine _laminæ_; the third set of twelve or thirteen; the fourth set of fifteen, and so on to the seventh or eighth set, when each grinder consists of twenty-two or twenty-three: and it may be added, that each succeeding grinder takes at least a year more than its predecessor to be completed."[85] As each tooth advances, only a small portion pierces the gum at once; one of twelve or fourteen _laminæ_, for instance, shows only two or three of these through the gum, the remainder being as yet imbedded in the jaw; and in fact the _tooth is complete at its fore part_, where it is required for mastication, _while behind it is still very incomplete_; the laminæ are successively perfected as they advance. The molar of an Elephant _can never, therefore, be seen in a perfect state_: for if it is not worn in front, the back part is not fully formed and is without fangs; and when the structure of the hinder portion is perfected, _the front part is already gone_. "When the complex molar cuts the gum, the cement is first rubbed off the digital summits; then their enamel cap is worn away, and the central dentine comes into play with a prominent enamel ring; the digital processes are next ground down to their common uniting base, and a transverse tract of dentine, with its wavy border of enamel, is exposed; finally, the transverse plates themselves are abraded to their common base of dentine, and a smooth and polished tract of that substance is produced. From this basis the roots of the molar are developed, and increase in length, to keep the worn crown on the grinding level, until the reproductive force is exhausted. When the whole extent of a grinder has thus successively come into play, its last part is reduced to a long fang supporting a smooth and polished field of dentine, with sometimes a few remnants of the bottom of the enamel folds at its hinder part. Then, having become useless, it is attacked by the absorbent action, by which, and the pressure of the succeeding tooth, it is finally shed."[86] With these physiological facts ascertained, let us proceed to the determination of the actual age of our noble Dauntelah. The molar in present use has a length of about nine inches, and a diameter of three and a half. Its crown is crossed by about eighteen enamel-plates; of which the anterior ones are much worn away, while the hinder ones can scarcely be counted with precision, as they have not wholly cut their way through the gum. These characters indicate the fifth molar (or set of molars) of the whole life-series. And the following facts will help us now to fix the actual age, at least approximately. The first molar cuts the gum at two weeks old, is in full use at three months, and is shed in the course of the second year. The second cuts the gum at about six months, and is shed in the fifth year. The third appears at two years, is in full use about the fifth year, and finally disappears about the ninth year. In the sixth year the fourth breaks from the gum, and lasts till the animal's twenty-fifth year. The fifth cuts the gum at the twentieth year, is entirely exposed soon after the fortieth, and is thrust out about the sixtieth year, by the advance of the sixth molar, which appears at about fifty years old, and probably lasts for half a century more. If others succeed this,--a seventh and even an eighth, as some assert,--these would carry on the Elephant's life to two or three centuries, in accordance with an ancient opinion, which is in some degree countenanced by modern observations. To come back, then, to the case before us, since the fifth molar has its fore part much worn, and the posterior laminæ scarcely yet protruded from the gum, it follows that this Elephant is now not far from the fortieth year of his life, a deduction which well agrees with the dimensions of his tusks, and his appearance of mature vigour. Can you detect a flaw in this reasoning? And yet how baseless the conclusion, which assigns a past existence of forty years to a creature called into existence this very day. X. PARALLELS AND PRECEDENTS. (_Man._) "Once, in the flight of ages past, There lived a Man,--and who was he? Mortal, howe'er thy lot be cast, That man resembled thee."--MONTGOMERY. We have knocked at the doors of the vegetable world, asking our questions; then at those of the lower tribes of the brute creation, and now at those of the higher forms; and we have received but one answer,--varying, indeed, in terms, but essentially the same in meaning,--from all. And now we have one more application to make; we have, still in our ideal peregrination, to seek out the newly-created form of our first progenitor, the primal Head of the Human Race. And here we behold him; not like the beasts that perish, but-- "Of far nobler shape, erect and tall, Godlike erect, with native honour clad, In naked majesty, as lord of all." The definitive question before us is this: Does the body of the Man just created present us with any evidences of a past existence, and if so, what are they? And that we may rightly judge of the matter, we will, as on former occasions, call in the aid of a skilful and experienced physiologist, to whom we will distinctly put the question. _The Physiologist's Report._ In replying to your inquiry concerning the proofs of a past existence in the Man before me, I must treat of him as a mere animal,--a creature having an organic being. And, first, I find every part of the surface of his body possessing a nearly uniform temperature, which is higher than that of the surrounding atmosphere. There is, moreover, on all parts of the body, a tinge of redness, more or less vivid in certain regions. The heat, and the carnation tinge, alike indicate the presence of blood, arterial blood, diffused throughout, and, in particular, occupying the capillaries of the superficial parts. Every drop of this blood is preceded and succeeded by other drops, every one of which has been impelled out of the heart by its constant contractions. But the very existence of this blood supposes the pre-existence of chyle and lymph, out of which it has been constructed. The chyle was formed out of chyme, changed by the action of the pancreatic and biliary secretions. Chyme is food, chemically altered by the action of the gastric juice. So that the blood, now coursing through the arteries and veins, implies the previous process of the reception of food. And these pancreatic and biliary secretions, which are essential to the conversion of chyme into chyle,--and therefore into blood,--do you ask their origin? They were prepared, the one by the pancreas, the other by the liver, from blood already existing,--blood _previously formed_ of chyle with the addition of bile, &c.--and so indefinitely. Again, the blood in these capillary arteries is of a bright scarlet hue, which it derives from its being charged with oxygen. This it received in the _lungs_, parting at the same time with the carbon which it had taken up in its former course. The lungs then must have existed _before_ the blood could be where and what it is, viz. arterial blood in the capillaries of the extremities; before it was driven out of the heart, since it was transmitted from the lungs through the pulmonary veins into the heart, thence to be pumped into the arterial system. But since all the tissues of the body are formed from the blood, the lungs were dependent on already-existing blood for their existence. And as the formative and nutrient power is lodged exclusively in _arterial_ blood, the very blood out of which the lungs were organized was dependent on lungs for oxygenation, without which it would have been effete and useless. Here then is a cycle of which I cannot trace the beginning. But further. On the extremities of the fingers and of the toes, there are broad horny _nails_. These I trace down to the curved line where they issue from beneath the skin, and whence every particle of each nail has issued in succession. They are composed of several strata of polygonal cells, which have all grown in reduplications of the skin, forming compressed curved sheaths (_follicles_); stratum after stratum of cells having been added to the base-line, as the nail perpetually grew forwards. About three months elapse from the emergence of a given stratum of cells, before that stratum becomes terminal; and therefore each of these twenty-four finger- and toe-nails is a witness to three months' past existence. [Illustration: GROWTH OF HAIR (_magnified_).] The head is clothed with luxuriant _hair_, composed of a multitude of individual fibres, each of which is an epidermic appendage, essentially similar to the nails. Every hair is contained at its basal extremity in a delicate follicle, where it terminates around a soft vascular bulb, made up of blood-vessels and nerves. On the surface of this living bulb the horny substance is continually secreted and deposited in layers, each of which in succession pushes forward those previously made, till the tip extrudes from the follicle of the skin, after which it continues to grow in the same way, as an external hair. The tip is gradually worn away; and thus the constant growth cannot, in general, cause it to exceed a certain given length. Each of the thousands of hairs with which this majestic head is clothed, bears witness to past time; and as the increase of hair is about an inch per month, and as this hair is about four inches in length, we have here thousands of witnesses to at least four months of previous history. The bones which make up the firm and stately fabric about which this human body is built, are no productions of a day. Long before this they existed in the form of cartilages. In these, minute arteries began to deposit particles of phosphate of lime, around certain centres of ossification, doing their work in a determinate order, and in regular lines, so as to form continuous fibres. These fibres, aggregated, and connected by others, soon formed a texture of spicula or thin plates. Now take as an example a cylindrical hollow bone, as that of the thigh. Here the spicula were arranged longitudinally, parallel to the axis of the bone: preserving the general form of the cartilage which constituted its scaffolding. But the bone required a progressive increase in size. In its early state, moreover, it was not hollow, but solid. Changes must have taken place to bring it to its present dimensions and condition. These were effected by the actual removal of some parts, simultaneously with the deposition of others. At a certain stage of ossification, cells were excavated by the action of the absorbent vessels, which carried away portions of bony matter lying in the axis of the cylindrical bone. Their place was supplied by an oily matter, which is the marrow. As the growth proceeded, while new layers were deposited on the outside of the bone, and at the end of the long fibres, the internal layers near the centre were removed by the absorbent vessels, so that the cavity was further enlarged. In this manner the outermost layer of the young bone gradually changed its relative situation, becoming more and more deeply buried by the new layers which were successively deposited, and which covered and surrounded it; until by the removal of all the layers situated near to the centre, it became the innermost layer, and was itself destined in its turn to disappear, leaving the new bone without a single particle which had entered into the composition of the original structure.[87] These processes have been the slow and gradual work of years, of the lapse of which years the bones are themselves eloquent witnesses. Within the mouth there are many _teeth_. I will not now speak of their exact number, nor of some other particulars concerning them, because I mean to return to them presently; but I look only at their general structure and origin. Each tooth consists of three distinct parts, the central portion, which is _ivory_; the exceedingly hard, polished, glassy coat of the crown, which is _enamel_; and a thin layer of bone around the fang, which is the _cement_. Before either of these appeared, a minute papillary process of vascular pulp was formed in a cavity of the jaw. Over the pulp was spread an excessively thin membrane, which secreted from the blood, and deposited, a thin shell of bony matter, or ivory, moulded on the form of the pulp. Successive layers of ivory were then added, from within; the pulp diminishing in a corresponding ratio. The cavity of the jaw at the same time deepened, and the pulp lengthened downward into the space thus provided; layers of bony substance being gradually deposited upon it, as above. [Illustration: SECTION OF HUMAN TOOTH (_magnified_).] The cavity itself was lined with a thick vascular membrane, united to the papilla at its base. Within the space lying between this membrane and the pulp, there was deposited from the wall of the former a soft, granular, non-vascular substance, known as the enamel organ. The cells on the inner surface of this substance then took the form of long, sub-parallel prisms, set in close array, perpendicular to the surface of the tooth. Earthy matter was progressively deposited in them, by which they became the exceedingly dense and hard enamel of the crown. The cement of the fang was then formed by a slight modification of the process which had produced the enamel. Here, then, are several distinct and important processes, effected in regular and immutable succession, each requiring time for its performance, and all undeniably witnessed-to by the structure of every tooth here seen. As I have thus proved the _fact_ of life existing in this human body for some time previous to the present moment, I now proceed to inquire how far its structure may throw light on the _actual duration_ of that past life. How far can we ascertain its chronology? The stature of the Man before me is about six feet. An infant at birth is from eighteen to twenty-one inches in length. At ten years old the average stature is about four feet. Six feet may be taken as the full adult height of man; and this is attained from the twenty-first to the twenty-fifth year. The stature of this individual would therefore indicate an age not less than twenty-one years. On the front of the throat I perceive a strongly-marked, angular prominence, formed by the union of the two plates of the thyroid cartilage. The prominence of this angle is due to the enlargement of the larynx; and it is accompanied by a deepening of the pitch of the voice, producing the full rich sounds that we have this instant heard, as the Man chanted his song of praise. These tones, and this projection of the thyroid cartilage, are equally distinctive marks of puberty, and do not appear till about the sixteenth or seventeenth year. The chin, and sides of the face, are clothed with a dense bush of crisp hair,--the beard. This is a distinctive mark of the adolescent period, and may be taken as indicating an age not less than twenty years. On again examining the mouth, I find the teeth are thirty-two in number; viz., four incisors, two canines, four pre-molars, and six true molars, in each jaw. None of these existed (at least visibly) during the first seven years of life; in that period they were represented by the milk-teeth of infancy. The appearance of the middle pair of incisors occurred at about the eighth year; the lateral incisors at nine; the first pre-molars at ten; the second at eleven; the canines at about twelve; the second molars at thirteen or fourteen; and the third molars, or _dentes sapientiæ_, at about seventeen or eighteen. The state of the dentition, then, points to an age certainly not less than the period just named. How much more it may be, we must gather from other sources. I come now to certain phenomena which are not appreciable to us on mere external examination; but which I am able with certainty to predicate. And the first of these is the proportion of arterial to venous blood in the capillaries. In infancy, the arterial capillaries contain far more blood than the capillary veins; in old age, the proportion is exactly reversed; whereas, in maturity, the ratio is just equal. Now, here there is a very small preponderance of arterial blood, indicating a period but slightly remote from maturity on the side of youth; well agreeing with the conclusion arrived at from previous premises, of some twenty to five-and-twenty years. Other and more marked manifestations occur in the condition of the skeleton. In the spine, I find _the spinous and transverse processes_ of the several vertebræ are completed by separate _epiphyses_, the ossification of which does not commence till after puberty, and the final union of which with the body of the bone does not occur till about the age of twenty-five years. Each _vertebra_, moreover, has attained a smooth annular _plate_ of solid bone, covering a surface that was previously rough and fissured, which is invariably added at the same period. The _ossification of the sacrum_ also has reached its culminating point. At the age of puberty, the component vertebræ began to unite from below upwards, and the two highest have now coalesced; which also marks a period of life not earlier than the twenty-fifth year. The whole united mass, moreover, is furnished on each side with thin bony plates, the appearance of which is no less characteristic of the same age. Each of the _ribs_ is here furnished with two _epiphyses_, one for the head and the other for the tubercle; the ossification of these began soon after puberty; but their union with the body of the bone, as presented here, has taken several years to accomplish. To come to the limbs, we find the _shoulder-blade_ presenting three _epiphyses_, one for the _coracoid_ process, one for the _acromion_, and one for the lower angle of the bone, the ossification of which begins soon after puberty, their union with the body of the bone taking place between the ages of twenty-two and twenty-five years. The _clavicle_ has an _epiphysis_ at its sternal end, which begins to form between the eighteenth and twentieth years, and is united to the rest of the bone a few years later. The consolidation of the shoulder-bone (_humerus_) is completed rather earlier; the large piece at the upper end, which is formed by the coalescence of the ossific centres of the head and two tuberosities, unites with the shaft at about the twentieth year; whilst its lower extremity is completed by the junction of the external condyle, and of the two parts of the articulating surface (previously united with each other), at about the seventeenth year, and by that of the internal condyle in the year following. The superior _epiphyses_ of the arm-bones (_radius_ and _ulna_) unite with their respective shafts at about the age of puberty; the inferior, which are of larger size, at about the twentieth year. The _epiphyses_ of the _metacarpal_ and _phalangeal bones_ (those of the hand and fingers) are united to their principals at about the twentieth year. In the _Lower Extremities_, the process of ossification is completed at nearly the same periods as that of the corresponding parts of the Upper. The consolidation of the hipbones (_ilium_, _ischium_, and _pubis_) to form the _os innominatum_, by the ossification of the triradiate cartilage that intervenes between them in the socket of the thigh (_acetabulum_), does not take place until after the period of puberty; and at this time additional _epiphyses_ begin to make their appearance on the crest of the _ilium_, on its anterior inferior spine, on the tuberosity of the _ischium_, and on the inner margin of the _pubes_, which are not finally joined to the bone until about the twenty-fifth year.[88] The concurrence of these conditions in the skeleton, the nearly balanced ratio of the bloods, the perfected dentition, the beard, the deepened voice, the prominent larynx, and the stature, combine to point out, with infallible precision, the age of this Man, as between twenty-five and thirty years. So far, then, we can with certainty trace back the history of this being, as an independent organism; but did his history then commence? O no; we can carry him much farther back than this. What means this curious depression in the centre of the abdomen, and the corrugated knob which occupies the cavity?[89] This is the NAVEL. The corrugation is the cicatrice left where once was attached the umbilical cord, and whence its remains, having died, sloughed away. This organ introduces us to the foetal life of Man; for it was the link of connexion between, the unborn infant and the parent; the channel, through whose arteries and veins the oxygenated and the effete blood passed to and from the parental system, when as yet the unused lungs had not received one breath of vital air. And thus the life of the individual Man before us passes, by a necessary retrogression, back to the life of another individual, from whose substance his own substance was formed by gemmation; one of the component cells of whose structure was the primordial cell, from which have been developed successively all the cells which now make up his mature and perfect organism. * * * * * How is it possible to avoid this conclusion? Has not the physiologist irrefragable grounds for it, founded on universal experience? Has not observation abundantly shown, that, wherever the bones, flesh, blood, teeth, nails, hair of man exist, the aggregate body has passed through stages exactly correspondent to those alluded to above, and has originated in the uterus of a mother, its foetal life being, so to speak, a budding out of hers? Has the combined experience of mankind ever seen a solitary exception to this law? How, then, can we refuse the concession that, in the individual before us, in whom we find all the phenomena that we are accustomed to associate with adult Man, repeated in the most exact verisimilitude, without a single flaw--how, I say, can we hesitate to assert that such was his origin too? And yet, in order to assert it, we must be prepared to adopt the old Pagan doctrine of the eternity of matter; _ex nihilo nihil fit_. But those with whom I argue are precluded from this, by my first Postulate. XI. PARALLELS AND PRECEDENTS. (_Germs._) "Every cell, like every individual Plant or Animal, is the product of a previous organism of the same kind."--(DR. CARPENTER, _Comp. Physiol._ § 347.) In the preceding examples I have assumed that every organic entity was created in that stage of its being which constitutes the acme of its peculiar development; when all its faculties are in their highest perfection, and when it is best fitted to reproduce its own image. From the very nature of things I judge that this was the actual fact;[90] since, if we suppose the formation of the primitive creatures in an undeveloped or infant condition, a period would require to lapse before the increase of the species could begin; which time would be wasted. To those, indeed, who receive as authority the testimony of the Holy Scripture, the matter stands on more than probable ground; for its statements, as to the condition of the things created, are clear and full: they were not seeds, and germs, and eggs, and embryos,--but "the tree yielding fruit whose seed was in itself,"--"great whales,"--"winged fowl,"--"the beast of the earth,"--and "man."[91] But I do not mean to shield myself behind authority. I have begged the _fact_ of creation; but not the truth, nor even the existence, of any historic document describing it. It is essential to my argument that any such be left entirely out of the question; and, for the present, I accordingly ignore the Bible. It is possible that some opponent may object to my assumption of maturity in created organisms. "Your deductions may be sound enough," such an one may say, "provided your newly-created Locust-tree had so many concentric cylinders of timber, your Tree-fern had a well-developed stem of leaf-bases, your Coral a great aggregation of polype-cells, your Tortoise a carapace of many-laminated plates, your Elephant a half-worn set of molars, and your Man a thoroughly ossified skeleton. But how do you know that either of these organisms was created in this mature stage? I will not deny that each was created,--was called suddenly out of non-entity into entity; but I believe, or at least I choose to believe,--that each was created in the simplest form in which it can exist; as the seed, the gemmule, the ovum, the--ahem!" Pray go on! you were about to say "the infant," or "the foetus," or "the embryo," probably; pray make your selection: which will you say? "Well, I hardly know. Because, if I choose the new-born infant, you will say, Its condition implies a nine months' pre-existence, certainly; not to speak of the absurdity of a new-born infant being cast out into an open world without a parent to feed it. If I say, The foetus, or the still more incipient embryo, I involve, at once, a pre-existent mother. I am afraid you have me there!" I think I have. However, let us take up the matter orderly, and proceed on the supposition that my previous examples must be all cancelled, and the question argued _de novo_, on the assumption that each organism was created in its least developed condition. It will not be considered necessary, I suppose, to look at any intermediate condition of the organisms. The argument which is based upon the leaf-scales of the Fern or the Palm would essentially apply to either of these plants when it first issues from the ground. At the period when it comprises but a single frond, the botanist would no more hesitate in pronouncing that the organism had passed through stages previous to that one, than he would when it possesses an elongated stipe; though, in the latter case, the evidences of the pre-existence are more patent to the uninstructed eye. He would say, The single frond implies, with absolute necessity, a spore in the one case, a seed in the other; and we need not to see either, to be assured that this must have preceded the leaf-stage. But you go farther back still. "The plant was created as a seed." Let us renew our imaginary tour at the epoch, or epochs (as many as you please), of creation, on this supposition. Here is a very young plant of the curious Seychelles Palm or Double Cocoa-nut (_Lodoicea Sechellarum_). A single frond is all that is yet developed, and this is as yet unexpanded, the pinnæ being still folded on the midrib, like a fan. Trace the frond down to its base. It springs from a thick horizontal cylindric process, which has also shot down a radicle into the soil. We trace the cylindrical stem along the surface of the soil, and find, lying on the ground, among the grass, but not buried, a great double nut, something like the two hemispheres of a human brain, or like a common cocoa-nut, half split open and healed. Out of this the thick stem has issued; and we find that it is only the cotyledon of the seed, that has prolonged its base in the process of germination, in order to throw up, clear of the nut, the plumule and radicle. We look at the great nut, and find, on the woody exterior of the fibrous pericarp, at the side opposite to that whence issues the cotyledon, a broad scar. What is this? It is the _mark left by the severance of a footstalk_, which united the fruit to the parent plant. This great drupe was once a small ovary seated in the centre of a three-petaled flower, which, with many others, issued out of a great spathe, a mass of inflorescence, and hung down from the base of the leafy coronal of an adult palm-tree. This scar is an irreproachable witness of the existence of the parent palm. Here, lying on the dry and dusty earth, is a brown flat bean of great hardness. This is a seed destined by and by to produce that splendid tree _Erythrina crista-galli_. But it has been just created. This bean bears on one of its edges an oval scar, very distinctly marked, called the _hilum_. This was the point of attachment of a short column, by which the seed was united to one of the sutures of a long pod, in the interior of which it lay, in company with several others like itself. This great legume or pod had been the bottom of the pistil of a papilionaceous flower, crowned by a tiny stigma, lodged in a sheath formed by the united stamens, and surrounded by a corolla of refulgent scarlet petals. Of course such a flower was not an independent organism; it was one of many that adorned a great tree, the history of whose life would carry us back through several generations of human years. [Illustration: GARDEN TULIP. Fig. 1. A flower with two petals removed, to show the ovary, _a_. Fig. 2. The same ovary, more mature, divided longitudinally; _b_, the unripe seeds, packed on each other; _c_, a portion of the same carpel, from which the seeds have been removed.] This single infolding leaf, that is just shooting from the soil, so small and feeble,--what of this? There are certainly no concentric cylinders of timber here: can we trace a previous history of this? Yes: by carefully removing the soil from the base, we see that it originates in a flat yellow seed--the seed of a Tulip. Here again we have no difficulty in detecting evidence of its former attachment. A great number of these seeds were once closely packed one on another, in each of the three carpels that constituted the capsule. And this capsule had been the oblong, three-sided ovary, which formed the body of the pistil in some beautiful Tulip. Do you observe these two round fleshy leaves, just peeping from the sandy earth? They are the earliest growths of a plant of _Arachis hypogæa_. In this case again, to understand the true relations of this organism, we must expose it wholly to view. Beneath the surface of the earth, then, I find that these seed-leaves are the two halves (_cotyledons_) of a kind of pea, which was formerly enclosed in a wrinkled skinny pod. But what is most interesting is that the pod is here, the cotyledons shooting out of it. And, attached to one end of the pod, here is a slender stalk, now withered and dry, which projects out of the ground into the air. [Illustration: GERMINATION OF EARTH-PEA.] Now here we have a beautiful link of connexion with the past. The plant before us does not ripen its seeds, and then drop them to care for themselves, as most plants do. "The young fruit, instead of being placed at the bottom of the calyx, as in other kinds of pulse, is found at the bottom and in the inside of a long slender tube, which looks like a flower-stalk. When the flower has withered, and the young fruit is fertilized, nothing but the bottom of the tube with its contents remains. At this period a small point projects from the summit of the young fruit, and gradually elongates, curving downwards towards the earth. At the same time the stalk of the fruit lengthens, until the small point strikes the earth, into which the now half-grown fruit is speedily forced, and where it finally ripens in what would seem a most unnatural position."[92] The young plant before us has been this moment created, and created in this incipient stage of growth: and yet there is, even here, an indubitable evidence, so far as physical phenomena can afford it, of a past history. It would be utterly impossible to select any stage in the life of the Earth-pea, which did not connect itself, visibly and palpably, with a previous stage. Let us return to the shore-loving Mangrove. You object to my assumption that it was created as a tree, with a well-branched stem elevated upon a series of arching roots; and to my deduction of pre-lapsed years for the formation of those roots. Very well. I give it up. You allow that the primitive Mangrove was created in some stage, but you contend for the germ-stage, the simplest condition of the plant, whatever that might be. Now, where shall we find it? In the first pair of developed leaves? They certainly point back to the cotyledons. To the cotyledons, then, let us look. Lo! the young plant is germinating before its connexion with the parent is severed. It is the singular habit of this tree, that its seeds are already in a growing condition, while they hang from the twig. Each seed is a long club-shaped body, with a bulbous base and a slender point, more or less produced. While it yet hangs from the branch, the radicle and crown of the root begin to grow, and gradually lengthen, until the tip reaches the soil, which it penetrates and thus roots itself; while those which depend from the higher branches, after growing for a while, drop, and, sticking in the mud, throw out roots from one end, and leaves from the other. [Illustration: SEED OF MANGROVE.] What have you gained, then, in this case, by going back to the germ? The germ as decisively asserts its origination from an already existing organism--the parent tree--as the flourishing tree witnesses its gradual development from a germ. The Mangrove could not by possibility have been created in any stage, consistent with the identity of the species with that which we behold now in the nineteenth century,--that did not show ocular evidence of a previous history;--evidence from the nature of things fallacious. It would be merely tiresome to go on through the vegetable kingdom. In every plant the simplest condition--viz. that of a spore or seed--depends on some development, or process, or series of processes, that have preceded it. Nor does the lapse of time between the previous process and the apparent result at all destroy their necessary connexion. In the case of the curious Misseltoes, the ovule does not appear till three months after the pollen has been shed; but when it does appear, its existence as an organism capable of developing the characteristic form of its species, is as truly dependent on the previous existence of the pollen, as if not an hour had intervened. Supposing the essential conditions of vegetable organisms to have been at the first what they are now; in other words, supposing specific identity to have been always maintained,--which I have demanded as a postulate for this argument,--it appears to me demonstrable, that every plant in the world presented at the moment of its creation evidences _prochronic_ development, in nowise to be distinguished from those on which we firmly rely as proving the lapse of time. But is the case otherwise in the animal world? We traced back the history of our Medusa through its marvellous series of gemmative developments, till we reached the minute Infusory-like gemmule, which is its simplest form. Now it is quite legitimate to assume that _this_, and not the pulmonigrade umbrelliform stage, was the one in which the new-created Medusa began existence. Have we, then, got rid of the evidence of past time, which we deduced from the successive changes through which the adult had passed? What is this ciliated planule, and whence comes it? It is the embryo discharged from the fringed ovary of a female Medusa; it has already passed through several changes of colour and form. It is now of a deep yellow colour; it has been violet; it has been colourless: it is now shaped like a dumb-bell; it was a globule; it had been a mulberry-mass. Yet earlier, it had been a component cell of the ovarian band, which divided the generative cavity from that of the stomach, in the parent Medusa. In like manner the ciliated gemmule from which was formed the "pluteus" of the Urchin, was dependent on the existence of a parent Urchin; the monadiform germ from which was developed the pentacrinus of the Feather-star, was originally hidden in the ovarian tubes of a parent Feather-Star: the infant _Serpula_ that deposited the first atoms of calcareous matter as a commenced tube, had begun its own existence in the body of a parent _Serpula_. It is true the evidence of the connexion between the germ and the parent is not in these low forms always patent to the eye; it is physiological. But it is not less conclusive to one who is able to appreciate its force. A physiologist is as sure that every germ, every ovum, in the Invertebrate animals, was produced by an animal of a former generation, as he is of the same fact in a Mammal, where his eye can see the scar of the umbilical cord. In many instances there is stronger, or rather more obvious and ordinarily appreciable, evidence of the link between the present and the past generation, than the physiological dependence. The world of Insects, which, from its immensity, and from the high organic rank of its members, affords us so exhaustless a mine of economical wonders,--is rich in examples to the point. A few of these I shall cite. The eggs of many Insects are not dropped anywhere, at random; for, as the newly-born young have limited powers of locomotion, and yet are in general able to subsist only on some particular kind of food, it is necessary that their birth should occur in the immediate proximity of such food: and therefore that the egg should be so placed. Now this circumstance would not be specially noteworthy if the locality selected for the deposition of the egg were the same as that in which the parent insect had been accustomed to find its own private enjoyments: we should reasonably say that the eggs were placed here, because the parents happened to be here. The case, however, is very different. We never find the egg of the Peacock Butterfly adhering to the leaf of a cabbage, nor that of the Garden White to the leaf of a nettle; but the nettle is invariably selected for the former, and a cruciferous plant for the latter. Yet there is nothing in the individual wants or likings of the Butterfly, in either case, to account for this. Both the one and the other flutter through the sunny air, alight to drink the water of some slushy pool, rest on the expanding flowers and probe them for nectar, or suck the exuding juices of an over-ripe fruit. But when did you ever see the gorgeous-eyed Peacock feeding on a nettle, or the White on a cabbage? Eagerly as they seek these plants, it is solely for the purpose of depositing their eggs where instinct teaches them their unborn progeny will find suitable food. Supposing, therefore, we had found the egg of either of these butterflies at the moment of its creation, we should assuredly have found it on the nettle or the cabbage (as the case might be); because to suppose it in any other situation would be equivalent to supposing it so placed as that the end of its creation--the life of the species created--would be _ipso facto_ frustrated. But, finding it so, the question naturally arises,--Why here, and not elsewhere? and the only possible answer, on the ground of phenomena, is, Because the parent chose this situation for it. And thus we are inevitably thrown back to an anterior generation, which is equivalent to past time. Again, if we had seen the egg of the Nut Weevil (_Balaninus nucum_) just come from the creative hand of God, we should certainly have found it within the immature soft-shelled hazel-nut, because there alone would the grub when hatched meet with "food convenient for" it. And yet if we had sought (ignorant of the fact of its recent creation) the reason of its being there, our acquaintance with entomology would have pointed to the parent beetle, who, with her jaws placed at the tip of a long slender snout, had bored a tiny hole in the tender shell, and had then projected the egg from her abdomen into the interior. The eggs of the _Oestridæ_--for example, the Worble of the Ox (_Oestrus bovis_) or the Bot of the Sheep (_Oe. ovis_)--would be discovered in no other circumstances than beneath the skin of the former, and at the edge of the nostrils of the latter. For these are the respective situations in which the egg is always deposited, that of the Worble hatching _in situ_, and forming a superficial abscess in communication with the external air, and that of the Sheep-bot producing a larva which crawls up the nostrils of the poor animal, till it finds a suitable resting-place in the frontal sinuses of the skull. To suppose the egg in any other circumstances than those which I have mentioned, would be to consign it to certain destruction. Yet does not its presence there bear witness to the eclectic care of the parent Gadfly, whose unerring instinct knew how to seek and select the right position? If you had set yourself to look for the egg of a _Pimpla manifestator_, a common Cuckoo-fly, where would you have looked for it, but in the fatty tissues of a wild bee's grub, that was lodged in a deep hole in some old post? If you had sought elsewhere, you would surely have been disappointed. And would not its presence there bear testimony to the lengthened ovipositor of the well-known brisk and busy fly, and to its remarkable habits?[93] The grub of the Pill Chafer or Tumble-dung Beetle (_Phanæus_) feeds on the ordure of _Mammalia_. And, in order that the newly-hatched young may have a copious supply of food at hand, the parent chafer with its jaws detaches a mass of recent ordure, which it then rolls over the ground with its hind feet, until it acquires a globular form, and a coating of earth or sand. An egg is then deposited in the centre of the ball, which is rolled into a hole made in the earth to receive it. The coating of earth drying and hardening, keeps the interior of the mass fresh and moist until the young grub is hatched, when it at once begins to devour its savoury and delicate provision. It would be vain to search for the egg of a _Cynips_ except within a vegetable gall, or at least within the tissues of a plant that are going to produce one. Take as an example _C. quercus_, which produces the spongy excrescence well known as the common Oak-apple. The female Gall-fly is furnished with an ovipositor in the shape of a very fine curved needle, with which she punctures the tender bark of an oak shoot, lodging an egg in the perforation. Stimulated by some fluid, probably, which is poured into the wound at the same time, the sap forms a peculiar tissue around the egg, swelling into a large ball, on which the young grub begins to feed eagerly, and in which it finds the only nutriment on which it could subsist. Now, if we had found the egg of a Gall-fly newly created, we should certainly have found it in a gall; and the gall would have afforded us indubitable evidence of the wounding of the vegetable tissues, and of the organ, secretion, and instinct of the tiny fly by which the process had been effected. The evidence would be irresistible, but of course it would be fallacious. Let us now look at a few examples in which the egg is found in invariable association not merely with something that the parent has found for it, but with something that has proceeded from her, a part of herself. Of this nature are the eggs of that beautiful, but most cacodious, lace-winged fly, _Chrysopa perla_. If you had seen one of these (or more) at the instant of its creation, you would have seen a tiny oval body placed at the extremity of an elastic footstalk half-an-inch in length, and as fine as a hair, standing erect from the surface of a leaf. This thread is composed of a gummy secretion, evolved in a gland attached to the oviduct of the female Lace-fly. When she deposits an egg, she first exudes a drop of this gum on the surface of a leaf, and then, elevating her abdomen, the viscid substance is drawn out in a thread, which presently hardening in the air, the egg is left at the tip of the filament. An experienced entomologist, on seeing this object, would have no hesitation in declaring the origin of the footstalk to be the gum-gland of the female _Chrysopa_; and yet he would certainly have drawn a false inference in the case that I am supposing. [Illustration: LACE-FLY AND EGGS.] Many Spiders enclose their eggs in an envelope, the produce of their own bowels. Take an interesting example, as narrated by the eloquent Mr. Kirby. "There is a Spider common under clods of earth (_Lycosa saccata_), which may at once be distinguished by a white globular silken bag, about the size of a pea, in which she has deposited her eggs, attached to the extremity of her body. Never miser clung to his treasure with more tenacious solicitude than this spider to her bag. Though apparently a considerable incumbrance, she carries it with her everywhere. If you deprive her of it, she makes the most strenuous efforts for its recovery; and no personal danger can force her to quit the precious load. Are her efforts ineffectual? a stupefying melancholy seems to seize her; and, when deprived of this first object of her cares, existence itself appears to have lost its charms. If she succeeds in regaining her bag, or you restore it to her, her actions demonstrate the excess of her joy. She eagerly seizes it, and with the utmost agility runs off with it to a place of security. "The attachment of this affectionate mother is not confined to her eggs. After the young spiders are hatched, they make their way out of the bag by an orifice which she is careful to open for them, and without which they could never escape; and then, like the young of the Surinam toad (_Rana pipa_), they attach themselves in clusters upon her back, belly, head, and even legs; and in this situation, where they present a very singular appearance, she carries them about with her, and feeds them until their first moult, when they are big enough to provide their own subsistence."[94] I waive the argument derived from the fact of the apparent necessity of the mother's care for the new-born young. But the mother's care is indispensable to the appearance of the young at all; not only because the eggs are the produce of her ovary, but also because the envelope which protects them is the produce of her spinning-glands. There is a furry moth, by no means uncommon, known to collectors as the Gipsy (_Hypogymna dispar_), the eggs of which require to be protected by an elaborate covering, either from extremes of temperature, from light, or from certain electric conditions of the atmosphere. The protection is afforded at the expense of the hair which clothed the mother herself. Her ovipositor is furnished with a pair of nippers, by means of which she plucks off her own hairs, and makes with them a flat cushion on the surface of a leaf. On this she deposits her eggs in successive layers; and when the full number is laid, she covers them with a roof of hair, slanting downwards and outwards from an apex, so artfully arranged, like the thatch of a cottage, as effectually to throw off water; each layer of hairs overlapping the preceding, and all preserving the same direction, so that, when finished, the work resembles a smooth and well brushed piece of fur. If, then, a patch of eggs newly-created had been subjected to our inspection, we should have found them snugly protected by their conical roof of thatch; and when we came to examine the thatch microscopically, we should have found it composed of the hairs of _Hypogymna_. And thus again we should have an indubitable and yet deceptive record of a preceding existence. The numerous species of the genus _Coccus_, to which we are indebted for cochineal, lac, and other products valuable in commerce, afford me an illustration of my argument, more striking than any of the above. In the case of the lac insect (_C. lacca_), for example, the female resembles a little hemispherical scale on the twig of a tree. At a certain period of her life, a pellucid, glutinous substance begins to exude from the margins of her body, which by and by completely covers it, cementing her firmly to the branch, from which she never afterwards moves. She now proceeds to lay her eggs, which one by one as they are extruded are thrust under her, between her abdomen and the surface of the branch. The result of this is, that when the whole are laid, they occupy pretty nearly the same position in relation to the mother as they did before, with this exception, that the abdominal integuments, which before were beneath them, are now above them, and are in close contact with those of the back, so that both together make a double, but still a thin, arched roof over the heap of eggs, which are thus protected till the hatching of the young, when they eat their way out of their long dead mother. Let me now make my usual application. You say the _Coccus_ was created not an adult insect, which would involve the prochronic stages of its metamorphosis, but as a germ, that is an egg (for the germ of an insect is an egg, and nothing else): well, here is a batch of Coccus-eggs just created, covered with the scaly roof which is necessary to their existence. But this scale is not a record of the mother, but the mother herself, _a prochronic mother_, of course! Other genera of this wonderful class of animals yield us evidences of a somewhat different character, in the structures which the parents form for the reception of their eggs. One of the most complex and elaborate pieces of mechanism found in any animal organ is the ovipositor of the Sawflies (_Tenthredinidæ_). I cannot here describe it at length; it may suffice to say that it consists of two saw-plates, working separately and in opposite directions, the teeth of which are cut into finer teeth; and two supporting plates, very similar to the saws in shape and appearance. The whole flat side of the saw is, moreover, covered with minute sharp points, which give the action of a rasp to the instrument, in addition to that of saw. By means of this complicated apparatus the parent fly cuts a groove in the twig of the proper shrub, say, a rose-bush. When it is made, the plates are slightly separated, and an egg is laid in the groove. The saw is now withdrawn, and a frothy secretion is deposited, which appears to be intended, by its hardening, to prevent the growth of the wood from closing upon the egg, before the time of hatching arrives. If, then, any of the species of _Tenthredo_ had been called into primal existence as an egg, it must have been within such a groove as this; and the groove, if carefully examined, would have presented evidences of having been formed and filled by the curious implement of the parent fly. Those obscure and obscene Insects, the Cockroach tribe (_Blattadæ_), secrete an extraordinary covering for the protection of their eggs. "Instead of being laid separately, the eggs are, when deposited, enclosed in a horny case, or capsule, variable in its form in different species but generally of a more or less compressed oval shape, resembling a small bean. There is a longitudinal slit in the margin of the capsule, each side of which is defended by a narrow serrated plate, fitting closely to its fellow. The inside of this egg-case is divided into two spaces, in each of which is a row of separate compartments, every one enclosing an egg, so that the whole resembles the pod of some leguminous vegetable. This capsule, with its precious contents, is constantly carried about by the female for a week or a fortnight, and is then fastened, by means of a glutinous fluid, in some safe locality. The slit of the capsule is strongly coated with cement, so as to be even stronger than the other parts. In this capsule the young larvæ are hatched, and immediately discharge a fluid which softens the cement, and enables them to push open the slit, through which they escape; after their exit the slit shuts again so closely, that it appears as entire as before. In some species it would seem that the females themselves liberate their offspring by seizing the capsule when the larvæ are fit for escape, and tearing it with the aid of their forelegs from end to end, by which means the enclosed larvæ are set at liberty."[95] It is impossible to read this description without being reminded of the manner in which the bean or other leguminous seed links itself with a former generation by means of the dehiscent legume, itself a production of the parent plant. And the same reasoning applies to this case, as to the other;--the egg, if the _Blatta_ was created in that stage, would triumphantly show in the pod with which it was covered, a record of past processes. So, once more, with the immense tribes of solitary Bees, Wasps, and Spheges. I shall mention but one example, from my own experience. It is the Dirt Dauber (_Pelopoeus flavipes_) of North America. The female of this elegant fly, when about to lay her eggs, builds up a tubular nest of cells with fine mud, which she makes by mingling and kneading road-dust with her saliva. Each tube consists of several cells, separated by transverse partitions of the mortar; and in each, before she closes it up, she lays a single egg, which she then covers with spiders which are to constitute the food of the grub when hatched, and to last it during the whole period of its larval growth. Dead spiders would not do, for their bodies would either dry up, or become putrescent long before the young grub could devour them. On the other hand, if a number of these fierce and carnivorous creatures were immured, in health, they would soon destroy one another. To obviate this, the parent-fly ingeniously stings every spider just sufficiently to paralyse, without killing it. Thus nearly a score of living spiders are packed away in a cell scarcely larger than a lady's thimble; and thus they remain fresh and succulent food for the larva, not only till it is ready to begin its eating task, but even to the close of its repast. I think this a particularly instructive example. The _Pelopoeus_ was indubitably created; for it exists. As indubitably it was created in some stage of its cyclical life-history. If as an imago, then I press the argument from the necessity of its previous metamorphoses. If as a pupa, or a larva, or an egg, each of these conditions of life was entirely passed as an inmate of the mud-walled cottage; which, cottage was built and stocked with food by the industry and skill of the parent-fly. The grub could not have lived without the stored spiders; the spiders could not have been stored (_normally_) without the agency of the fly. In some other instances the connexion between germ and parent is patent to the eye. The beautiful Star-fish, _Cribella_, passes through all its infant metamorphoses, changing from an ovum to an Infusory, thence to a Pluteus (or what is analogous to it), thence to a Star-fish, all in the marsupium provided for the occasion, by the drawing together of the arms of the patient mother. The female _Brachionus_ carries its deposited eggs attached to the hinder part of its body; and thus we can trace, through their transparent coats, the gradual development of the organs of the embryo,--the coloured eye, the rotatory cilia, the complex mastax,--and even detect the vigorous movements of these and other parts, while yet carried hither and thither by the parent. [Illustration: FEMALE BRACHIONUS, WITH EGGS.] But further, in the class from which I have taken this last illustration--that of the ROTIFERA--there are examples of viviparous genera; and these, because of the perfect transparency of all the integuments, are peculiarly instructive and germane to my argument. In _Rotifer macrurus_ the ovary with its germinal vesicles is distinctly seen occupying one side of the animal. From this one of the vesicles enlarges, until it becomes a long-oval translucent sac, nearly filling the whole left side of the visceral cavity. A kind of spasmodic movement is suddenly observed in this oblong ovum, and instantly we see, in its place, a well-developed living young; as distinctly visible as if it were excluded. It lies in a bent position, with its foot upturned; is nearly half the length of the parent; is furnished with a proboscis, with a pair of crimson eyes, with ciliary wheels, with a mastax whose toothed hemispheres frequently work vigorously, and with all the viscera proper to the species. [Illustration: PREGNANT ASPLANCHNA. _a._ _Unborn young._] In the beautiful, comparatively large, and economically singular genus, _Asplanchna_, the same process of development can be watched with perfect facility through every stage. In the body of the female parent, as transparent as the clearest glass, the band-like ovary is seen floating in the visceral cavity, with several ova in various degrees of advancement. We trace one of these till it becomes a manifestly living young in the ovisac, lying along at the bottom of the parental cavity, more than one-third of whose volume is occupied by it:--supposing it to be a female infant. All its organs,--the eyes, the jaws, the stomach, the pancreatic glands, _the ovary with its nuclei_, the muscles, the rotatory cilia, &c. can be traced with the utmost distinctness long before birth, and its motions are strong and voluntary. Neither in this case, nor in that of _Rotifer_, does the young animal pass through any metamorphosis; the unborn young has the full development of the parent, in every respect but size. In each case, the _visible_ life-history of the individual commences not at birth, but at a period long antecedent, if indeed it can be said to commence at all, where we see it gradually developed from a nucleus, which was an integral part of the parental ovary, _even before that parent's birth_. In the case of the amusing little Water-fleas (_Daphnia_), we have another example of viviparous generation, which, owing to the same cause as in the ROTIFERA,--the transparency of the integument, can be followed through all its stages by the eye of the observer. The eggs of this little Crustacean are deposited in a special chamber within the valves of the parent, where they are hatched. The young remain in their receptacle for a period, which varies according to the temperature, but long enough for them to undergo important changes in structure, and to pass their first moult.[96] Here, again, it is impossible to select a condition which does not take hold of a pre-existence; for the youngest independent stage is dependent on earlier stages; and these are passed in visible connexion with the parent. It is true there is in this genus, another mode of reproduction, by means of eggs which are thrown off enveloped in an organic covering, called the ephippium. If this condition be selected for the argument of my supposed opponent, I reply that it amounts to nearly the same thing; only the case will then come into the category of those animals whose earliest stages are protected by coverings formed from the body of the parent,--like the _Hypogymna_, and the Cockroach, already alluded to. Where then, in these species, can we possibly select a stage of life, which is not inseparably and even visibly connected with a previous stage? If we come to the vertebrate creatures, the argument becomes assuredly not less convincing. The formidable Shark, which we considered as a well-toothed adult ready for slaughter, let us suppose to have been created in the harmlessness of infancy. It is a slender thing, some ten or twelve inches long, bent upon itself, inclosing in the ring thus made, the vitellus or yelk-bag, the contents of which are in process of being absorbed into the abdomen. But the whole,--Shark, yelk-bag, and all--is imprisoned in a brown horny capsule, that looks like a pillow-case, with long tapes appended to the four corners. This very peculiar protecting capsule points clearly to a peculiar structure in the parent. The embryo was not inclosed in the pillow-case, at its first formation; but, in the course of its descent from the ovary through the oviduct, it had to pass a region of the latter, where was a thick glandular mass,--the nidamental gland,--whose office it was to secrete a dense layer of albumen, with which, the embryo became invested. This substance took the form of the flattened purse, or pillow-case, with produced angles, above described, and on its exclusion from the duct assumed a very tough horny consistence, and a dark mahogany colour. The comparative anatomist would, therefore, without the least hesitation, refer the origin of the investing capsule to the nidamental glands of the female Shark; but supposing the embryo to be but just created, his physiological science would only lead him to a false conclusion. If the Tree-frog afforded us evidence of pre-existent time, in the metamorphosis which it must naturally have experienced from the tadpole to the reptilian condition, what shall we say to that strange and uncouth member of the same class,--the Surinam Toad (_Pipa_)? Little would be gained by selecting the germ-stage, as the presumed epoch of creation in this case; for, according to the extraordinary economy of this genus, the male acts as midwife, and the female as wet-nurse, to the hopeful progeny. "As fast as the female deposits her eggs, the male who attends her arranges them on her broad back, to the number of fifty or upwards. The contact of these eggs with the skin appears to produce a sort of inflammation; the skin of the back swells, and becomes covered with pits or cells, which enclose each a single egg, the surface of the back resembling the closed cells of a honeycomb. The female now betakes herself to the water; and in these cells the eggs are not only hatched, but the tadpoles undergo their metamorphosis, emerging in a perfect condition, though very small, after a lapse of _eighty-two days_ from the time in which the eggs were placed in their respective pits." To a tyro in animal physiology it might seem that the smooth rounded egg of a bird or a lizard, presents an example of an organism in the simplest possible condition, and in a stage which, if any can be, is independent of anything that went before. But is it so? Let us see. Here is the egg of the common Fowl. I take it in my hand, and perceive nothing but an uniform, smooth, hard, white surface. This I break, and find that it is a thin layer of calcareous substance, which, on microscopical examination, proves to be composed of minute polygonal particles, so agglutinated as to leave open spaces in the interstices of their contiguous angles. Below this calcareous shell I find a membrane (_membrana putaminis_), which seems, from its thinness in most parts, to be single, but which is separated into two layers at the large end of the egg. [Illustration: HEN'S EGG.] Within this membrane there is another (_the chalaza_) which, closely enveloping the yelk, passes off from it towards each extremity of the egg in the form of a twisted cord. Then comes a delicate membrane (_memb. vitelli_) in close contact with, and enveloping the orange-coloured yelk; which latter carries, on one point of its globular surface, the thin _blastoderm_, or germinal membrane. The yelk-globe, fastened by its twisted _chalazæ_, is suspended in a glairy fluid (albumen), which fills the space between it and the _membrana putaminis_. This fluid, though apparently homogeneous, is really composed of many layers, and the innermost of these it is which is condensed into the _chalaza_. Such, then, is the complex structure of this apparently simple object. What light can it throw on our inquiry? Each of these component parts bears witness to a succession of past periods. The yelk with its germ was first formed, escaping naked, or clothed only with its own excessively delicate membrane, from its ovisac into the oviduct. Through the course of this tube it now slowly descended, receiving successive investments as it proceeded. The albumen was deposited layer upon layer from the mucous membrane of the upper part of the oviduct; the first depositions condensing into the _chalaza_. By and by it came down to a region of the oviduct where a tenacious secretion was poured out, which, investing the albumen, soon hardened into a substance resembling thin parchment, and formed the _membrana putaminis_; two successive layers of this were deposited, between which a bubble of gas, chiefly composed of oxygen generated in the interval, was inclosed. Then it descended still farther, to a part where the lining membrane of the duct was endowed with the power of secreting calcareous matter, which, as above stated, was deposited in a thin layer of polygonal atoms. And now, having received all its components, and having arrived at the orifice of the duct, the egg was laid. Here, then, there is abundant evidence of successive processes, which must have preceded the existence of this complete and perfect egg. But there is yet one more evidence which I have reserved to the last, because it is peculiarly distinct and palpable, even to the senses. The _chalaza_, we see, is twisted at each pole of the yelk-globe, until it resembles a piece of twine: what is the meaning of this? It was, as I observed, deposited as a loosely enveloping membrane in the upper part of the oviduct; the yelk-globe, however, was progressively descending; and, as it descended, _it continually revolved upon its axis_; by means of which rotation the investing membrane was gathered at each pole into a spirally twisted cord, stretching from the yelk to the ends of the _membrana putaminis_. Thus it presents us with an unmistakeable record of what took place in the earlier periods of the descent. We saw distinct traces of the past in the structure of a feather. But the feathers have already begun to develop before the young bird leaves the egg. And the structure of the egg carries us back to the oviduct of the parent-fowl. At what stage of existence, then, could a bird, by possibility, have been created, which did not present distinct records of prochronic development? If we come to the MAMMALIA, the impossibility of finding such a stage becomes only more and more obvious. For it is a law in physiology, that the higher the grade of organization assigned to any being, the more it is assisted in infancy by the parent. "This law is remarkably exemplified in the class MAMMALIA, which unquestionably ranks at the head of the animal kingdom, in respect to degree of intelligence and general elevation of structure. It is the universal and most prominent characteristic of this class, that the young are retained within the body of the female parent, until they have made considerable progress in their development; that, whilst there, they derive their support almost immediately from her blood; and that they are afterwards nourished for some time by a secretion which she affords."[97] The foetus of the Kangaroo, when expelled from the womb, is scarcely more than an inch in length. Its limbs and its tail are indeed formed, but the imperfect creature has been compared to an earthworm, for the colour and semi-transparency of the integument. In this condition it is unable to find and seize the nipple, and equally unable to draw sustenance therefrom, by its own unaided efforts. The _milk is ejected_, by the _muscular action of the mother_, into the throat of the foetus, and there is a peculiar and beautiful contrivance to obviate the danger of the injected fluid's passing into the trachea instead of the oesophagus. Yet, from this helpless naked condition to that of the active, well-clothed, experienced young, able to quit the maternal pouch at will, and flee to it for protection, there is a well-understood and perfectly appreciable concatenation of stages, each of which looks back to, and depends on, those previously existing. And, during the whole of these, the mother's presence is necessary to the comfort, and, for the greater part of them, to the very existence of the infant. Thus, once more, there is no condition of the animal, on which we may fix, as being so simple, as to have no retrospective history. The umbilical cicatrix I have already alluded to; but I may be permitted to mention it again; because, in all the higher MAMMALIA, at least, it exists, throughout life, an eloquent witness to the organic connexion of the individual with a mother, and therefore to her pre-existence. If it were legitimate to suppose that the first individual of the species Man was created in the condition answering to that of a new-born infant, there would still be the need of maternal milk for its sustenance, and maternal care for its protection, for a considerable period; while, if we carry on the suggested stage to the period when this provision is no longer indispensable, the development of hair, nails, bones, &c., will have proceeded through many stages. And, in either condition, the navel cord or its cicatrix remains, to testify to something anterior to both. XII. THE CONCLUSION. "We have no experience in the creation of worlds." CHALMERS. We have passed, in review before us the whole organic world: and the result is uniform; that no example can be selected from the vast vegetable kingdom, none from the vast animal kingdom, which did not at the instant of its creation present indubitable evidences of a previous history. This is not put forth as a _hypothesis_, but as a _necessity_; I do not say that it was _probably_ so, but that it was _certainly_ so; not that it _may have been thus_, but that it _could not have been otherwise_. I do not touch the inorganic world: my acquaintance with chemistry is inadequate for this: perhaps the same law does not extend to the inorganic elements: perhaps their developments, and combinations are not, like the economy of plants and animals, essentially and exclusively cyclical: perhaps carbon and oxygen and hydrogen could be created in conditions, which obviously did not depend on any previously existing conditions. This I do not know: I neither affirm nor deny it. But I think I have demonstrated in these pages, that such a cyclical character does attach to, and is inseparable from, the history of all organic essences; and that creation can be nothing else than a series of irruptions into circles: that, supposing the irruption to have been made at what part of the circle we please, and varying this condition indefinitely at will,--we cannot avoid the conclusion that each organism was from the first marked with the records of a previous being. But since creation and previous history are inconsistent with each other; as the very idea of the creation of an organism excludes the idea of pre-existence of that organism, or of any part of it; it follows, that such records are _false_, so far as they testify to time; that the developments and processes thus recorded have been produced without time, or are what I have called _prochronic_. Nor is this conclusion in the least degree affected by the actual chronology of creation. The phenomena were equally eloquent, and equally false, whether any individual organism were created six thousand years ago, or innumerable ages; whether primitively, or after the successive creations and annihilations of former organisms. The law of creation supersedes the law of nature; so far, at least, as the organic world is concerned. The law of nature, established by universal experience, is, that its phenomena depend upon certain natural antecedents: the law of creation is, that the same phenomena depend upon _no_ antecedents. The philosopher who should infer the antecedents from the phenomena alone, without having considered the law of creation, would be liable to form totally false conclusions. In order to be secure from error, he must first assure himself that creation is eliminated from the category of facts which he is investigating; and this he could do only when the facts come within the sphere of personal observation, or of historic testimony. Up to such a period of antiquity as is covered by credible history, and within such a field of observation as history may be considered fairly cognisant of,--the inference of physical antecedents from physical phenomena, in the animal or vegetable world, is legitimate and true. But, beyond that period, I cannot safely deduce the same conclusion; because I cannot tell but that at any given moment included in my inquiry, creation may have occurred, and have been the absolute beginning of the circular series. The question of the actual age of any species, whether plant or animal, is one which cannot be answered, except on historic testimony. The sequence of cause and effect is not adequate to answer it; for a legitimate use of this principle, supposing it the only element of the inquiry, would inevitably lead us to the eternity of all existing organic life. One of the familiar street-exhibitions in the metropolis is a tiny coach and horses of glittering metal; which, by means of simple machinery, course round and round the margin of a circular table. Let us suppose two youths of philosophical turn to come up during the process. They gaze for a while, and one asks his companion the following question. "How long do you suppose that coach has been running round?" "How long! for an indefinite period, for aught I know. I have counted twenty-two turns, and can see no change: nor can I suggest any point where the course could have begun." Here a shrewd lad, carrying a grocer's basket, breaks in. "Oh no; there have been only six-and-twenty turns altogether. Four turns had been made when you came up. The whole began by the man taking the carriage out of a box; then he set it down out there, just opposite to us, and gave it a little push with his finger, and it has been running ever since. I saw him do it." Now perhaps you will say that a glance at the machinery beneath the table would show in a moment how many turns had been made, and how many could be made. Very true: but what if the tramp had locked up his clock-work, and would not let you look at it? The only evidence worth a rush is that of the lad who saw the whirligig set a-going. I wish it to be distinctly understood, that I am not proving the exact or approximate antiquity of the globe we inhabit. I am not attempting to show that it has existed for no more than six thousand years. I wish this to be distinctly stated, because I am sure I shall meet with many opponents unfair enough, or illogical enough, to misrepresent or misunderstand my argument, and sound the trumpet of victory, because I cannot demonstrate _that_. _All_ I set myself to do, is to invalidate the testimony of the witness relied on for the indefinitely remote antiquity; to show that in a very large and important field of nature, evidence exactly analogous to that relied on would inevitably lead to a false conclusion, and must, therefore, be rejected, or received only contingently; received only as indicative of probability, and that only in the absence of any positive witness to the contrary. Perhaps it may be objected, that there is no sufficient analogy between the phenomena from which the past history of a single organism is inferred, and those from which the past history of a world is inferred. Is there not? Permit me to repeat an illustration I have already used. The geologist finds a fossil skeleton. His acquaintance with anatomy enables him to pronounce that the objects found are bones. He sees cylinders, condyles, cavities for the marrow, scars of attachment of muscles and tendons, foramina for the passage of nerves and blood-vessels; he finds the internal structure, no less than the form and surface, such as to leave not a doubt that these are real _bones_. Now universal experience has taught him that bones imply the existence of flesh; that flesh implies blood; that blood implies life; that life implies time. He therefore concludes unhesitatingly, that this skeleton was once alive, and that time passed over it in that living condition. Is not this process of reasoning exactly parallel to that which he would have pursued if he had examined an animal the moment after its creation, (supposing this fact to be unknown to him,) and by which he would in like manner have inferred past time? And where is the vital difference between the two cases, which would operate to make a conclusion which is manifestly false in the one case, necessarily true in the other? One of the most eminent of living botanists has set forth in striking terms the parallelism which I am suggesting. Speaking of the _shoot_ as the vegetable individual, and the woody trunk as a kind of ever-accumulating ground, which supports successive generations of shoots, he uses the following comparison. "The history of the grand development of nature on the surface of our globe presents an analogy, which may perhaps serve to set this relation in a clear light. The successive geological formations superposed during the course of countless ages, present, buried in their depths, the traces of as many formations of the organic world, each of which carpeted the then superior stratum of the earth with a new life, until it found its own grave in the succeeding formation, when a new uprising of organic life took its place. In the same way, the stem of a tree is a multistratified ground, in whose layers the history of earlier growths is legibly preserved. The number of the woody layers indicates the number of the generations which have perished, _i. e._ the age of the whole tree: a distinct annual ring is the monument of a vigorous season, an indistinct one of a bad season, a sickly one (which is often found among healthy ones) indicates the unhealthiness of the foliage of that particular year. The practised woodman can decipher many facts of the past in the layers of the trunk; _e.g._ a good season for foliage or for seed, damage by frost or by insects, &c."[98] In order to perfect the analogy between an organism and the world, so as to show that the law which prevails in the one obtains also in the other, it would be necessary to prove that the development of the physical history of the world is circular, like that already shown to characterise the course of organic nature. And this I cannot prove. But neither, as I think, can the contrary be proved. The life of _the individual_ consists of a series of processes which are cyclical. In the tree this is shown by the successive growths and deaths of series of leaves: in the animal by the development and exuviation of nails, hair, epidermis, &c. The life of _the species_ consists of a series of processes which are cyclical. This has been sufficiently illustrated in the preceding pages, in the successive developments and deaths of generations of individuals. We have reason to believe that species die out, and are replaced by other species, like the individuals which belong to the species, and the organs which belong to the individual. But is the life of _the species_ a circle returning into itself? In other words, if we could take a sufficiently large view of the whole plan of nature, should we discern that the existence of species [Greek: d] necessarily involved the pre-existence of species [Greek: g], and must inevitably be followed by species [Greek: e]? Should we be able to trace the same sort of relation between the tiger of Bengal and the fossil tiger of the Yorkshire caves, between _Elephas Indicus_ and _Elephas primigenius_, as subsists between the leaves of 1857 and the leaves of 1856; or between the oak now flourishing in Sherwood Forest and that of Robin Hood's day, from whose acorn it sprang?[99] I dare not say, we should; though I think it highly probable. But I think you will not dare to say, we should _not_.[100] It is certain that, when the Omnipotent God proposed to create a given organism, the course of that organism was present to his idea, as an ever revolving circle, without beginning and without end. He created it at some point in the circle, and gave it thus an arbitrary beginning; but one which involved all previous rotations of the circle, though only as ideal, or, in other phrase, prochronic. Is it not possible--I do not ask for more--that, in like manner, the natural course of the world was projected in his idea as a perfect whole, and that He determined to create it at some point of that course, which act, however, should involve previous stages, though only ideal or prochronic? All naturalists have speculated upon the great plan of Nature; a grand array of organic essences, in which every species should be related in like ratio to its fellow species, by certain affinities, without gaps and without redundancies; the whole constituting a beautiful and perfect unity, a harmonious scheme, worthy of the infinite Mind that conceived it. Such a perfect plan has never been presented by any existing fauna or flora; nor is it made up by uniting the fossil faunas and floras to the recent ones; _yet the discovery of the fossil world has made a very signal approach to the filling up of the great outline_; and the more minutely this has been investigated, the more have hiatuses been bridged over, which before yawned between species and species, and links of connexion have been supplied which before were lacking.[101] It is not necessary,--at least it does not seem so to me,--that all the members of this mighty commonwealth should have an actual, a diachronic existence; anymore than that, in the creation of a man, his foetal, infantile, and adolescent stages should have an actual, diachronic existence, though these are essential to his normal life-history. Nor would their diachronism be more certainly inferrible from the physical traces of them, in the one case than in the other. In the newly-created Man, the proofs of successive processes requiring time, in the skin, hairs, nails, bones, &c. could in no respect be distinguished from the like proofs in a Man of to-day; yet the developments to which they respectively testify are widely different from each other, so far as regards the element of time. Who will say that the suggestion, _that the strata of the surface of the earth, with their fossil floras and faunas, may possibly belong to a prochronic development of the mighty plan of the life-history of this world_,--who will dare to say that such a suggestion is a self-evident absurdity? If we had no example of such a procedure, we might be justified in dealing cavalierly with the hypothesis; but it has been shown that, without a solitary exception, the whole of the vast vegetable and animal kingdoms were created,--mark! I do not say _may_ have been, but MUST have been created--on this principle of a prochronic development, with distinctly traceable records. It was _the law of organic creation_. It may be objected, that, to assume the world to have been created with fossil skeletons in its crust,--skeletons of animals that never really existed,--is to charge the Creator with forming objects whose sole purpose was to deceive us. The reply is obvious. Were the concentric timber-rings of a created tree formed merely to deceive? Were the growth lines of a created shell intended to deceive? Was the navel of the created Man intended to deceive him into the persuasion that he had had a parent?[102] These peculiarities of structure were inseparable from the adult stage of these creatures respectively, without which they would not have been what they were. The Locust-tree could not have been an adult _Hymenæa_, without concentric rings;--nay, it could not have been an exogenous tree at all. The _Dione_ could not have been a _Dione_ without those foliations and spines that form its generic character. The Man would not have been a Man without a navel. To the physiologist this is obvious; but some unscientific reader may say, Could not God have created plants and animals without these retrospective marks? I distinctly reply, No! not so as to preserve their specific identity with those with which we are familiar. A Tree-fern without scars on the trunk! A Palm without leaf-bases! A Bean without a hilum! A Tortoise without laminæ on its plates! A Carp without concentric lines on its scales! A Bird without feathers! A Mammal without hairs, or claws, or teeth, or bones, or blood! A Foetus without a placenta! I have indeed written the preceding pages in vain, if I have not demonstrated, in a multitude of examples, the absolute necessity of retrospective phenomena in newly-created organisms. But if it can be undeniably shown in one single example, our failure to perceive it in ninety-nine other instances would in nowise invalidate the deduction from that one. Granted that you can triumphantly convict me of a _non-sequitur_, in ninety-nine out of every hundred of the cases in which I have attempted to show this connexion; still, if I have conclusively proved that in one solitary instance an animal or a plant was created with but one solitary evidence of pre-development, the principle for which I contend is established. I trust, however, it does not rest on one example, nor on twenty, nor on a hundred. It may be thought that I have multiplied my illustrations needlessly: ten times as many might have been given. I wished to show that the proof is of a cumulative character: a single good example would, indeed, have established the principle; but I wished to show how widely applicable it is; that it is, indeed, of universal application in the organic kingdoms. If, then, the existence of retrospective marks, visible and tangible proofs of processes which were prochronic, was so necessary to organic essences, that they could not have been created without them,--is it absurd to suggest the _possibility_ (I do no more) that the world itself was created under the influence of the same law, with visible tangible proofs of developments and processes, which yet were only prochronic? Admit for a moment, as a hypothesis, that the Creator had before his mind a projection of the whole life-history of the globe, commencing with any point which the geologist may imagine to have been a fit commencing point, and ending with some unimaginable acme in the indefinitely distant future. He determines to call this idea into actual existence, not at the supposed commencing point, but at some stage or other of its course.[103] It is clear, then, that at the selected stage it appears, exactly as it would have appeared at that moment of its history, if all the preceding eras of its history had been real. Just as the new-created Man was, at the first moment of his existence, a man of twenty, or five-and-twenty, or thirty years old; physically, palpably, visibly, so old, though not really, not diachronically. He appeared precisely what he would have appeared had he lived so many years. Let us suppose that this present year 1857 had been the particular epoch in the projected life-history of the world, which the Creator selected as the era of its actual beginning. At his fiat it appears; but in what condition? Its actual condition at this moment:--whatever is now existent would appear, precisely as it does appear. There would be cities filled with swarms of men; there would be houses half-built; castles fallen into ruins; pictures on artists' easels just sketched in; wardrobes filled with half-worn garments; ships sailing over the sea; marks of birds' footsteps on the mud; skeletons whitening the desert sands; human bodies in every stage of decay in the burial-grounds. These and millions of other traces of the past would be found, _because they are found in the world now_; they belong to the present age of the world; and if it had pleased God to call into existence this globe at _this_ epoch of its life-history, the whole of which lay like a map before his infinite mind, it would certainly have presented all these phenomena; not to puzzle the philosopher, but because they are inseparable from the condition of the world at the selected moment of irruption into its history; because they constitute its condition; they make it what it is. Hence the minuteness and undeniableness of the proofs of life which geologists rely on so confidently, and present with such justifiable triumph, do not in the least militate against my principle. The marks of Hyænas' teeth on the bones of Kirkdale cave; the infant skeletons associated with adult skeletons of the same species; the abundance of coprolites; the foot-tracks of Birds and Reptiles; the glacier-scratches on rocks; and hundreds of other beautiful and most irresistible evidences of pre-existence, I do not wish to undervalue, nor to explain away. On the hypothesis that the actual commencing point of the world's history was subsequent to the occurrence of such things in the perfect ideal whole, these phenomena would appear precisely as if the facts themselves had been diachronic, instead of prochronic, as was really the case.[104] Perhaps some one will say, "All this might be tenable, supposing the world were an organism. Your argument goes to show that organic essences in every stage of their existence present proofs of pre-existence; but what analogy is there between the lifeless inorganic globe (in which evidences of past processes are apparent, independent of the fossil organisms), and a living organic being,--plant or animal?" I answer, The point in the economy of the organic creatures, on which their prochronism rests, is not the organic, but the circular condition of their being. The problem, then, to be solved, before we can certainly determine the question of analogy between the globe and the organism, is this:--Is the life-history of the globe a cycle? If it is (and there are many reasons why this is probable), then I am sure prochronism must have been evident at its creation, since there is no point in a circle which does not imply previous points. At all events, geologists cannot prove that it is not. Wherever we can discern a cyclical condition, there the law of which I am treating must hold good; and it certainly obtains in other things beside organisms. When the inorganic crust of the globe was first cleft to contain rivers, whence came the water that flowed through the fissures? A river is the produce of rivulets, which issue from mountain springs; these originate in the water that percolates through the soil; and this is derived from the rains, and snows, and dews, that are deposited from the atmosphere. But there would be no deposition from the atmosphere if the water had not first been carried up by evaporation; and the vaporable fluid is obtained from the moistened soil; from the lakes and rivers; and from the seas and oceans, whose loss is perpetually recruited from the flowing rivers. Here, then, we get a circle closely analogous to that of organic being. Was a given drop of water created as a component particle of a running stream? Its position and condition looked back to the mountain spring whence it must naturally have issued. Was it called into being in the spring? It looked up to the surface, whence it must have oozed. Was it formed on the surface? It looked to the clouds, whence it must have dropped. Was it created in the cloud? It looked down to the surface of the lake or sea, whence it must have been raised. Was it created in the lake? It looked to the river, whence it must have flowed. The chief pelagic currents, which have hitherto so often been the destruction of the navigator, but which may yet become his able and subject servants, flow in circular systems. There is such an one in the southern part of the Indian Ocean, known as the Hurricane Region; another immense one ever running round and round the North Pacific; and, above all, that wondrous river of hot water--a river whose well-marked banks are not solid earth, but cold water--the Gulf Stream. "The fruit of trees belonging to the torrid zone of America is annually cast ashore on the western coasts of Ireland and Norway. Pennant observes that the seeds of plants which grow in Jamaica, Cuba, and the adjacent countries, are collected on the shores of the Hebrides. Thither also barrels of French wine, the remains of vessels wrecked in the West Indian seas, have been carried. In 1809 His Majesty's ship _Little Belt_ was dismasted at Halifax, Nova Scotia, and her bowsprit was found, eighteen months after, in the Basque Roads. The mainmast of the _Tilbury_, buried off Hispaniola in the Seven Years' war, was brought to our shores."[105] These facts are dependent on the eastward set of this majestic current; and so is another great physical fact of immeasurable importance to us;--the superiority in temperature of the western shores of Europe over the eastern shores of North America. The harbour of St. John's, Newfoundland, is frequently fast closed by ice in the month of June; yet the latitude of St. John's is considerably south of that of the port of Brest, in France. Impelled by the rotatory motion of the earth, and by the trade-wind,[106] the equatorial waters of the Atlantic are ever urged, a broad and rapid river, into the Caribbean sea, and the Gulf of Mexico, the narrowing shores of which compress the stream as in a funnel. The Andes here present a slender but impregnable barrier to its further progress westward; and the trend of the Isthmus turns it to the northward. Still finding no outlet, the impatient current, like a wild-beast pacing round its cage, courses the Gulf of Mexico, doubles the peninsula of Florida, and pursues its way first to the north-east, and then to the east, crossing the Atlantic in a retrograde direction, until it laves with its warm billows the coasts of Europe. Here it turns to the southward, and after embracing the "Fortunate" isles that lie off the African shores,--the Azores, the Madeiras, and the Canaries,--it joins the great equatorial set beneath the trade-wind, and returns on its westward course. This mighty circulation of water must have been going on from the instant that the earth commenced rotating on its axis, or (granting this to have been chronologically subsequent) from the instant the Atlantic occupied its present bed. Whether sooner or later, it commenced at _some_ instant; but at that instant all the previous elements of the circle were presupposed, and a boundless succession of former circles. An intelligent stranger, looking on the movement immediately after its commencement, but ignorant of its origin, would not be able to assign any limit to its past duration. From his observation of the velocity of the current in different parts of the circle, he would say with confidence,--"These identical particles of water, which I see now urged on their ceaseless course towards the middle of the North Atlantic, were, yesterday morning at this hour, in the latitude of the mouth of the Chesapeake; on the morning before, off Cape Hatteras, on the morning before that, off Cape Lookout;" and so backwards interminably. Whether the economy of the globe is circular, or not, I am not in a position to show. But its movements certainly are; and so are the movements of all the myriad worlds with which astronomy is conversant. Asteroids, planets, satellites, comets, suns,--nay, even the stellar universe itself--obey _in their motions_, the grand universal law of circularity. Take any one of these;--our Moon. When its orbital motion commenced, it commenced at some point or other of the circle which it describes in its course around the earth. The pre-existence, or at least the co-existence, of the Earth, and also that of the Sun, are necessary to its motion. Supposing it possible for a spectator, furnished with modern astronomical knowledge, to have looked at that instant on the newly-spun orb, would he not confidently have inferred, from its position at that moment, its position a week before? Would he not have felt able to indicate with unhesitating certainty the solar and lunar eclipses of a century or a chiliad before, just as he now calculates the time of the eclipse that marked the death of Herod the Great? Undoubtedly he would; for he would assume the constancy of those movements which modern science has deduced from the observations of many centuries; and, granting him the fact of their constancy, we could not invalidate his conclusions. Yet _what_ would he have shown? The conditions and phenomena of bodies before they had begun to exist. The conditions are legitimately deducible; but they are prochronic conditions. The mention of the celestial orbs suggests to remembrance the famous argument for the vast antiquity of the material universe, founded on the time which is required for the propulsion of light. I believe it owes its origin to Sir William Herschel. Speaking of the known velocity of light in connexion with the immense distance of certain nebulæ, that eminent astronomer made these remarks:-- "Hence it follows, that, when we... see an object of the calculated distance at which one of these very remote nebulæ may still be perceived... the rays of light which convey its image to the eye must have been more than nineteen hundred and ten thousand, that is, almost _two millions_, of years on their way; and that, consequently, so many years ago, this object must already have had an existence in the sidereal heavens, in order to send out those rays by which we now perceive it."[107] The notion has been amplified, with some interesting details, by a writer in the _Scottish Congregational Magazine_ for _January 1847_; who thus throws the statements into a tabular form, and comments on them. "From the Moon, light comes to the earth in 1-1/4 second " the Sun " " in 8 minutes " Jupiter " " in 52 " " Uranus " " in 2 hours " a fixed Star of 1st magnitude -- 3 to 12 years " " 2d " 20 " " " 3d " 30 " " " 4th " 45 " " " 5th " 66 " " " 6th " 96 " " " 7th " 180 " " " 12th " 4000 " "Now, as we see objects by the rays of light passing from those objects to our eye, it follows that we do not perceive the heavenly bodies, _as they are_ at the moment of our seeing them, but _as they were_ at the time the rays of light by which we see them left those bodies. Thus when we look at the moon, we see her, not as she is at the moment of our beholding her disc, but as she was a second and a quarter before; for instance, we see her not at the moment of her rising above the horizon, but 1-1/4 second after she has risen. The sun also when he appears to us to have just passed the meridian, has already passed it by 8 minutes. So, in like manner, of the planets and the fixed stars. We see Jupiter, not as he is at the moment of our catching a sight of him, but as he was 52 minutes before. Uranus appears to us, not as he is at the moment of our discovering him, but as he was 2 hours previously. And a star of the 12th magnitude presents itself to our eye as it was 4,000 years ago: so that, suppose such a star to have been annihilated 3,000 years back, it would still be visible on the earth's surface for 1,000 years to come: or, suppose a star of the same magnitude had been created at the time the Israelites left Egypt, it will not be perceptible on the earth for nearly 700 years from this date." Beautiful, and at first sight unanswerable as this argument is, it falls to the ground before the spear-touch of our Ithuriel, the doctrine of prochronism. There is nothing more improbable in the notion that the sensible undulation was created at the observer's eye, with all the pre-requisite undulations prochronic, than in the notion that blood was created in the capillaries of the first human body. The latter we have seen to be a fact: is the former an impossibility? It may perhaps be said:--"The traces of prochronism you have adduced in created organisms may be granted, because they are inseparable from the presumed condition of those organisms respectively. The blood in the vessels, the hair, the teeth, the nails, may afford evidences of past processes; but then those are only past stages of what yet exists. The case, however, is not parallel with the fossil skeletons, many of which have no connexion with anything now existing. The concentric rings of a timber-tree are essential to its adult state; but how is the existence of the _Pterodactyle_ or the _Megatherium_ essential to that of the recent _Draco volans_, or the South American Sloth? Can you show in the new-formed creature any trace of some organ which does not come into its present condition of being,--of something which has quite passed away?" Perhaps I can. The very concentric rings of the tree are considered by botanists as, in some sense, dead. The paradoxical dictum of Schleiden,--"No tree has leaves,"[108]--is grounded on this circumstance, that the woody portion of the mass is the inert result of former generations, and that the present race of leaves is growing, not out of the woody portion of the tree, but out of its herbaceous extremities, "which grow upon the woody stem _as upon a ground_, formed by the process of vegetation. This common ground, namely, the woody stem, _which is almost lifeless_ in comparison with the herbaceous parts engaged in active growth, is annually covered with a vigorous sheath under the protecting bark; and this sheath is the ground of the nourishment of all the vegetating herbaceous extremities."[109] The polygonal plates into which the bark of the _Testudinaria_ divides, not only show many superposed laminæ, at any given moment of its adult condition, but also bear witness, in the broad existent surface of each one, to former laminæ, yet older than the oldest now present, which have disintegrated and dropped off. The Palm and the Tree-fern show, in their trunk-scars, evidences of organs which have completely died away and disappeared; while, between these scars and the generation of living fronds, there is, at any given moment of the tree's history, a series of fronds which are quite dead and dry, but which have not yet disappeared. The _Nerita_, a genus of beautiful shells from the tropical seas, dissolves away and removes, in the progress of growth, the spiral column, which originally formed the axis of development; so that, in adult age, the spiral direction of the whole testifies to the past existence of a column which has quite disappeared. In that species of _Murex_,[110] which, on account of the long and slender rostellum, and the spines with which it is covered, is known to collectors as the Thorny Woodcock (_M. tenuispina_), the shelly spines of the earlier whorls would interfere with such as came, in process of development, to be superposed on them; for they cross the area which is to be the cavity enclosed by the advancing lip. They are, however, removed by absorption; but not so completely but that traces may still be discovered where they formerly existed: evidences of the quondam existence of what exists no longer. Towards one side of the upper surface of the pretty Star-fish, _Cribella rosea_, (as in many other species of Star-fishes,) there is a curious little mark, known as the _madreporic plate_, the use of which has greatly puzzled naturalists. Sars, the Norwegian zoologist, has unveiled the mystery.[111] The young larva, before it assumes the stellar form, is furnished with a sort of thick column, divided into four diverging clubbed arms, which are adhering organs, ancillary to locomotion. In the process of development, however, new locomotive organs are formed; and this four-fold column, being no longer needed, sloughs away; and that so completely, that not a trace of its existence remains, _except this scar_, or "_madreporic plate_;" which is therefore a permanent record of something that has quite passed away. But the closest parallel to the relation borne by the skeleton of an extinct species to an extant one, is presented by that of the hilum to a seed, or of the umbilicus to a mammal. Each of these is a legible and undeniable, record of a being, whose individuality was totally distinct from that of the being by which it is presented, and of which all vestiges have disappeared, _save this record_. Nor is the parallel founded on obscure or rare examples; both the umbilicus and the hilum are generally conspicuous; and both are extensively found in their respective kingdoms, the former pervading the viviparous Vertebrata, the latter characterising the whole of the cotyledonous types of vegetation. Once more. An objection may arise to the reception of the prochronic principle, on the ground that the examples I have adduced are not to be compared, in point of grandeur, with the mighty revolutions, which are presumed to have written their records in the crust of the globe; and that hence no analogy can be fairly drawn from one to the other. To the philosopher, however, there is no great or small, as there is none in the works of God. We have every reason to believe that He has wrought by the same laws in all portions of his universe: the principle on which an apple falls from the branch to the ground, is the same as that which keeps the planet Neptune in the solar system. I have shown that the principle of prochronic development obtains wherever we are able to test it; that is, wherever another principle, that of _cyclicism_, exists; whether the cycle be that of a gnat's metamorphosis, or of a planet's orbit. The distinction of great or small, grand or mean, does not apply to it. If it cannot be proved to be universal, it is only because we are not sufficiently acquainted with some of the economies of nature to be able to pronounce with certainty whether they are cyclical or not. I am not aware of any natural process, in which its existence can be absolutely denied. And this makes all the difference in the world between my position and that of the old simple-minded observers, with which a superficial reader might think it to possess a good deal in common. A century ago, people used to talk of _lusus naturæ_; of a certain _plastic power_ in nature; of abortive or initiative attempts at making things which were never perfected; of imitations, in one kingdom, of the proper subjects of another, (as plants were supposed to be imitated by the frost on a window-pane, and by the dendritic forms of metals). Still later, many persons have been inclined to take refuge from the conclusions of geology in the absolute sovereignty of God, asking,--"Could not the Omnipotent Creator make the fossils in the strata, just as they now appear?" It has always been felt to be a sufficient answer to such a demand, that no reason could be adduced for such an exercise of mere power; and that it would be unworthy of the Allwise God. But this is a totally different thing from that for which I am contending. I am endeavouring to show that a grand LAW exists, by which, in two great departments of nature at least, the analogues of the fossil skeletons were formed without pre-existence. An arbitrary acting, and an acting on fixed and general laws, have nothing in common with each other. Finally, the acceptance of the principles presented in this volume, even in their fullest extent, would not, in the least degree, affect the study of scientific geology. The character and order of the strata; their disruptions and displacements and injections; the successive floras and faunas; and all the other phenomena, would be _facts_ still. They would still be, as now, legitimate subjects of examination and inquiry. I do not know that a single conclusion, now accepted, would need to be given up, except that of actual chronology. And even in respect of this, it would be rather a modification than a relinquishment of what is at present held; we might still speak of the inconceivably long duration of the processes in question, provided we understand _ideal_ instead of _actual_ time;--that the duration was projected in the mind of God, and not really existent. The zoologist would still use the fossil forms of non-existing animals, to illustrate the mutual analogies of species and groups. His recognition of their prochronism would in nowise interfere with his endeavours to assign to each its position in the scale of organic being. He would still legitimately treat it as an entity; an essential constituent of the great Plan of Nature; because he would recognise the Plan itself as an entity, though only an ideal entity, existing only in the Divine Conception. He would still use the stony skeletons for the inculcation of lessons on the skill and power of God in creation; and would find them a rich mine of instruction, affording some examples of the adaptation of structure to function, which are not yielded by any extant species. Such are the elongation of the little finger in _Pterodactylus_, for the extension of the alar membrane; and the deflexion of the inferior incisors in _Dinotherium_, for the purposes of digging or anchorage. And still would he find, in the fossil forms, evidences of that complacency in beauty, which has prompted the Adorable Workmaster to paint the rose in blushing hues, and to weave the fine lace of the dragonfly's wing. The whorls of the _Gyroceras_, the foliaceous or zigzag sutures of the _Ammonites_, and the radiating pattern of _Smithia_, are not less elegant than anything of the kind in existing creation, in which, however, they have no parallels. In short, the readings of the "stone book" will be found not less worthy of God who wrote them, not less worthy of man who deciphers them, if we consider them as prochronically, than if we judge them diachronically, produced. [Illustration: GYROCERAS.] * * * * * Here I close my labours. How far I have succeeded in accomplishing the task to which I bent myself, it is not for me to judge. Others will determine that; and I am quite sure it will be determined fairly, on the whole. To prevent misapprehension, however, it may be as well to enunciate what the task was, which I prescribed, especially because other (collateral, hypothetical) points have been mooted in these pages. All, then, that I consider myself responsible for is summed up in these sentences:-- I. The conclusions hitherto received have been but inferences deduced from certain premises: the witness who reveals the premises does _not_ testify to the inferences. II. The process of deducing the inferences has been liable to a vast incoming of error, arising from the operation of a _Law_, proved to exist, but hitherto unrecognised. III. The amount of the error thus produced we have no means of knowing; much less of eliminating it. IV. The whole of the facts deposed to by this witness are irrelevant to the question; and the witness is, therefore, out of court. V. The field is left clear and undisputed for the one Witness on the opposite side, whose testimony is as follows:-- "IN SIX DAYS JEHOVAH MADE HEAVEN AND EARTH, THE SEA, AND ALL THAT IN THEM IS." INDEX. Agave, 147. Ammonites, appearance of, 58. profusion of, 65. Amphibia, foot-prints of, 52, 56. Anoplotherium, 69. Antediluvian hypothesis, 9. untenable, 51. Babbage, Mr., opinions of, 25. Babiroussa, 262. Bamboo, 134. Banyan, 164. Barnacle, development of, 217. Basalt, formation of, 66, 91. Beaches, raised, 83. Beard, 284. Beetle, egg of, 310. Belemnites, 58. Bignonia, 168. Birds, earliest, 69. gigantic, 82. feathers of, 253. Blackwood, opinions of, 9. Blocks, transport of, 78. Blood, 275, 285. Bones, structure of, 279. Botryllus, metamorphoses of, 222. Brachionus, eggs of, 321. Bracts, development of, 166. Brown, Rev. J. M., opinions of, 9. Bulbs, growth of, 153, 156. Buprestis, 214. Butterflies, eggs of, 307. Butterfly-flower, 150. Cabbage-palm, 144. Carboniferous deposits, 44. Case-flies, 209. Cassowary, 252. Caverns, bone, 76, 88. Ceiba, 174. Cephalaspis, 44. Chalk formation, 64. Chalmers, Dr., opinions of, 19. Chronology of globe, 30, 339. Circularity of organic life, 113, 336, 351. Clavagella, 225. Coal, age of, 50. extent of, 46. origin of, 47. Coccus, economy of, 315. Cockburn, Rev. Sir W., opinions of, 14. Cockroach, egg-case of, 318. Conybeare, Dr., opinions of, 20. Coprolites, 60. Coral polypes, 40, 41, 45. activity of, 86. Couch-grass, 135. Cow, circular life of, 121. Cowry, 231. Crab, metamorphosis of, 216. Crag and tail, 55. formation, 75. Crinoids, abundance of, 58. Creation, extent of, 22. fact of, 110. law of, 337, 368. periods of, 15. What is it? 123. Cribella, metamorphosis of, 321. Crocodile, 248. Cuckoo-fly, egg of, 309. Cumbrian formations, 36. Currents, oceanic, 356. Cuttlefish, shell of, 237. Cycads, 60. Cyclicism, 336, 351. of the globe, 354. of inorganic nature, 355. of celestial orbs, 359. Cysticercus, 196. Daphnia, economy of, 325. Dauber, economy of, 320. Days of creation, 15. Deductions, fallible, 2. Deer, Irish, 84. Deltas, 85. Deposits, earthy, 87. Depressions and elevations, 81. Development hypothesis, 111. Devonian formations, 42. Diachronism, 125, 346. Diatomaceæ in chalk, 64. Dinotherium, 72, 370. Dione, 228. Disturbances of strata, 54, 66. Dodo, 84. Double cocoa-nut, 296. Earth-pea, germination of, 299. Echinus, 190. Eggs of fowl, 328. of insects, 306. Elephant, dentition of, 266. fossil, 73. Elevations and depressions, 81. Encephalartos, 161. Euphorbia, 164. Erythrina, 297. Fairholm, Mr., opinions of, 12. Feather, growth of, 253. Feather-star, 193, 305. Fig, Australian, 162. Indian, 164. Fishes, cycloid, 68. earliest, 44. sauroid, 52. Fishes, scales of, 242. Foetus of kangaroo, 333. Footprints, 57. Foraminifera, 64, 70. Frog, 57. Gall-fly, egg of, 310. Ganges, delta of, 85. Geography, changes of, 60, 66,70. Geology, in need of caution, 4. Germs, hypothesis of, 294. Gilt-head, 241. Glaciers, theory of, 79. Gladiolus, 152. Globe, chronology of, 30. cyclicism of, 354. density of, 37. Gnats, egg-raft of, 207. Goliathus, 205. Granite, 37. decomposition and reconstruction of, 38. Grass-tree, 154. Gray, Mr., opinions of, 20. Grit, 46. Gulf-stream, 356. Gyroceras, 371. Hair, growth of, 278. Harris, Dr., opinions of, 19. Hawkmoth, 118. Hertfordshire, strata of, 33. Hippopotamus, 263. fossil, 73. Hitchcock, Dr., opinions of, 21. Horns of ibex, 257. stag, 258. Horse, 260. Hylæosaurus, 62. Hypotheses, variety of, 27. Ibex, 257. Ichthyosaurus, 59. Iguanodon, 62. Infusoria in chalk, 64. Insects, eggs of, 306. Iriartea, 139. Julus, 212. Kangaroo, foetus of, 333. Kirkdale cave, 77. Labyrinthodon, 57. Lace-fly, egg of, 311. Lady-fern, 116. Law of creation, 337, 368, 371. Leaf-scars of fern, 130. Lepralia, 219. Lias, 58. Light, velocity of, 360. Lily, 156. Limestone coral, 45. Locust-tree. 177. London clay, 67. Loranthus, 169. "_Lusus Naturæ_," 368. Macbrair, Mr., opinions of, 10. Madrepore, 183. Mammal, earliest, 63. Mammoth, 73. Man, introduction of, 83. structure of, 275. Mangrove, 173. germination of, 301. Marsupials, 82. Mastodon, 73. Medusa, 188, 304. Megalosaurus, 61. Melicerta, 210. Miller, Hugh, opinions of, 15. Millepore, 183. Moa, 84. Moho, 84. Moon, cyclicism of, 359. Mosasaurus, 65. Moth, eggs of, 314. Mountains, upheaving of, 66, 70. Murex, 233, 365. Nails, growth of, 277. Nature, circularity of, 113. plan of, 345, 369. Nautilus, 235. Navel, evidence from, 289, 334. Nerita, axis of, 365. Noah's flood, 6. Oestridæ, economy of, 309. Oolitic system, 58, 60; duration of, 63. Opossum, 63. Organ-pipe, 185. Organic life a circle, 113, 122. Organisms, earliest, 40. Orchis, 152. Palm-leaf, young, 145. Penn, Mr., opinions of, 11. Phenomena, evidence of, delusive, 337. Plants of London clay, 67. "Plastic power," 368. Plates of tortoise, 250. Plesiosaurus, 59. Plumularia, 119. Powell, Professor, opinions of, 26. Prickly pear, 172. Prochronism, 125, 346, 368. dependent on cyclicism, 354. "Protoplast," opinions of, 23. Pterodactyle, 62, 370. Raindrops, 58. Rattan, 145. Rattlesnake, 247. Reptiles, Marine, 16, 59. Rhinoceros, fossil, 73. Roots, aerial, of fig, 163. of iriartea, 139. of mangrove, 173. of pandanus, 138. Rotifera, viviparous, 322. Sackcloth of palms, 141. Sandstone, age of, 50. new red, 56. old red, 42. Saw-fly, eggs of, 317. Scale of fish, 242. Scarlet-runner, economy of, 113. Screw-pine, 136. Scripture, efforts to reconcile with geology, 5. literal sense of, 4. Sea-urchin, 191, 305. Sea-pen, 182. Secondary epoch, 66. Sedgwick, Professor, on past time, 98. opinions of, 17. Selaginella, 133. Senses, evidence of, 1. Serpent, earliest, 68. Serpula, 198, 305. Sharks, 52, 58, 243. egg of, 326. Shells, now fossilizing, 89. Shore-crab, 216. Silk-cotton tree, 174. Silurian formations, 40. Skeleton, human, 286. Skeletons, evidence from, 105, 340. Sloths, fossil, 82. Smith, Dr. Pye, opinions of, 22. Smithia, elegance of, 371. Species, persistence of, 110. Spider, eggs of, 313. Stag, 258. Star-fish, madreporic plate of, 366. Stars, light from fixed, 361. Stature of man, 284. Strata, disturbances of, 54. number of, 37. Strombus, 230. Sugar-palm, 141. Sumner, Dr., opinions of, 19. Surinam toad, 327. Sword-fish, 240. Tapeworm, 195. Tapir, 69. Teeth of babiroussa, 262. Teeth of crocodile, 249. elephant, 268. hippopotamus, 263. horse, 261. man, 281, 285. shark, 243. Termes, 203. Terebella, 201. Tertiary epoch, 66. fauna, 76. Testimony, divine, 2; dear to many scientific men, 5; by some rejected, 8. Testudinaria, 158. Thames Tunnel, strata of, 32. Thyroid cartilage, 284. Timber, rings of, 178, 342, 349. Tortoise, 250. Tour of inspection, 127. Traveller's tree, 148. Tree-fern, age of, 128. Tree-frog, 246. Trilobites, 41. Truth, value of, 7. Tulip, seed of, 298. Tulip-tree, 165. Turner, Sharon, opinions of, 18. Tusk of elephant, 266. Ure, Dr., opinions of, 10. Venus, prickly, 228. "Vestiges," hypothesis of, 27, 111. Volcanic action, 55, 66, 86. Weevil, economy of, 308. Whalebone, 255. White ant, 203. World, projected history of, 351. Yorkshire, strata of, 33. Young, Dr., opinions of, 13. * * * * * FOOTNOTES: [1] Dr. Lardner; Museum of Science and Art, vol. i. p. 81. [2] As Cuvier, Buckland, and many others. On the question whether the phenomena of Geology can be comprised within the short period formerly assigned to them, the Rev. Samuel Charles Wilts long ago observed: "Buckland, Sedgwick, Faber, Chalmers, Conybeare, and many other Christian geologists, strove long with themselves to believe that they could: and they did not give up the hope, or seek for a new interpretation of the sacred text, till they considered themselves driven from their position by such facts as we have stated. If, _even now, a reasonable, or we might say_ POSSIBLE _solution were offered, they would_, we feel persuaded, _gladly revert_ to their original opinion."--_Christian Observer_, August, 1834. [3] Reflections on Geology. [4] Geology and Geologists. [5] New System of Geology. [6] Mineral and Mosaic Geologies, p. 430. [7] Geology of Scripture. [8] Scriptural Geology, _passim._ [9] Letter to Buckland, 15, _et seq._ [10] Origen, Augustine, &c. [11] Testimony of the Rocks, p. 144 [12] Discourse (5th Ed.), 115. [13] Sac. Hist. of World. [14] Rec. of Creation. [15] Nat. Theology. [16] Pre-Adamite Earth. [17] Harmony of Scripture and Geology. [18] Christian Observer, 1834. [19] Religion of Geology, Lect. ii. [20] Scripture and Geology. [21] I am not _replying_ to any of these conflicting opinions; else, with respect to this one, I might consider it sufficient to adduce the _ipsissima verba_ of the inspired text. Not a word is said of Adam's being "nine hundred and thirty years _old_;" the plain statement is as follows:--"And _all the days that Adam lived_ were nine hundred and thirty years." (Gen. v. 5.) [22] "Protoplast," pp. 58, 59; p. 325; 2d. Ed. [23] Unity of Worlds (1856), pp. 488, 493. [24] "A geological truth must command our assent as powerfully as that of the existence of our own minds, or of the Deity himself; and any revelation which stands opposed to such truths _must be false_. The geologist has therefore _nothing to do with revealed religion_ in his scientific inquiries."--_Edinb. Review_, xv. 16. [25] Ansted's Ancient World, 18. [26] Ansted's Ancient World, 30. [27] Scripture and Geology, 371. (Ed. 1855.) [28] "It is by no means unlikely that some beds of coal were derived from the mass of vegetable matter present at one time on the surface, and submerged suddenly. It is only necessary to refer to the accounts of vegetation in some of the extremely moist, warm islands in the southern hemisphere, where the ground is occasionally covered with eight or ten feet of decaying vegetable matter at one time, to be satisfied that this is at least possible." [29] Ansted's Anc. World, 75. [30] M'Culloch's System of Geology, i. 506. [31] Origin of Coal. [32] Testimony of the Rocks, p. 78. [33] Mr. Newman suggests that they were "marsupial bats" (Zoologist, p. 129). I have adopted his attitudes, but have not ventured to give them mammalian ears. [34] In Tennant's "List of Brit. Fossils" (1847), but two species--a Brachiopod and a Gastropod--are mentioned as common to the Chalk and the London Clay. They are _Terebratula striatula_, and _Pyrula Smithii_. [35] Ansted's Anc. World, 267. [36] Reliquiæ Diluvianæ. [37] Travels through the Alps, p. 19. [38] Prof. Owen, in his admirable account of the _Mylodon_, has mentioned a fact which brings us very vividly into contact with its personal history. He shows that the animal got its living by overturning vast trees, doing the work by main strength, and feeding on the leaves. The fall of the tree might occasionally put the animal in peril; and in the specimen examined there is proof of such danger having been incurred. The skull had undergone two fractures during the life of the animal, one of which was entirely healed, and the other partially. The former exhibits the outer tables of bone broken by a fracture four inches long, near the orbit. The other is more extensive, and behind, being five inches long, and three broad, and over the brain. The inner plate had in both these cases defended the brain from any serious injury, and the animal seems to have been recovering from the latter accident at the time of its death. [39] Naturalist's Voyage, _passim_. [40] The Indians of North America knew that the Mastodon had a trunk; a fact which (though the anatomist infers it from the bones of the skull) it is difficult to imagine them to be acquainted with, except by tradition from those who had seen the living animal. [41] Ansted; Phys. Geography, 82. [42] An interesting fact relating to the Brazilian caves was communicated to Dr. Mantell. "M. Claussen, in the course of his researches, discovered a cavern, the stalagmite floor of which was entire. On penetrating the sparry crust, he found the usual ossiferous bed; but pressing engagements compelled him to leave the deposit unexplored. After an interval of some years, M. Claussen again visited the cavern, and found the excavation he had made completely filled up with stalagmite, the floor being as entire as on his first entrance. On breaking through this newly-formed incrustation, it was found to be distinctly marked with lines of dark-coloured sediment, alternating with the crystalline stalactite. Reasoning on the probable cause of this appearance, M. Claussen sagaciously concluded that it arose from the alternation of the wet and dry seasons. During the drought of summer, the sand and dust of the parched land were wafted into the caves and fissures, and this earthy layer was covered during the rainy season by stalagmite, from the water that percolated through the limestone, and deposited calc-spar on the floor. The number of alternate layers of spar and sediment tallied with the years that had elapsed since his first visit; and on breaking up the ancient bed of stalagmite, he found the same natural register of the annual variations of the seasons; every layer dug through presented a uniform alternation of sediment and spar; and as the botanist ascertains the age of an ancient dicotyledonous tree from the annual circles of growth, in like manner the geologist attempted to calculate the period that had elapsed since the commencement of these ossiferous deposits of the cave; and although the inference, from want of time and means to conduct the inquiry with precision, can only be accepted as a rough calculation, yet it is interesting to learn that the time indicated by this natural chronometer, since the extinct mammalian forms were interred, amounted to many thousand years."--(_Petrifactions and their Teachings_, p. 481.) [43] Bibliothèque Univers., March, 1852. [44] "It is now admitted by all competent persons, that the formation even of those strata which are _nearest the surface_, must have occupied vast periods, probably millions of years, in arriving at their present state."--BABBAGE, _Ninth Bridgewater Treatise_, p. 67. [45] Geology of Central France. [46] "Though perfect knowledge is not possessed, yet there are reasons for believing that the duration of life to testacean individuals of the present race is several years. But who can state the _proportion_ which the average length of life to the individual mollusc or conchifer, bears to the duration appointed by the Creator to the species? Take any one of the six or seven thousand known recent species; let it be a _Buccinum_, of which 120 species are ascertained, (one of which is the commonly known _whelk_;) or a _Cypræa_, comprising about as many, (a well-known species is on almost every mantel-piece, the _tiger-cowry_;) or an _Ostrea_ (_oyster_), of which 130 species are described. We have reason to think that the individuals have a natural life of at least six or seven years; but we have no reason to suppose that any one species has died out, since the Adamic creation. May we then, for the sake of an illustrative argument, take the duration of testacean species, one with another, at one thousand times the life of the individual? May we say six thousand years? We are dealing very liberally with our opponents. Yet in examining the vertical evidences of the cessations of the fossil species, marks are found of an entire change in the forms of animal life; we find such cessations and changes to have occurred MANY times in the thickness of but a few hundred feet of these late-rocks."--DR. J. PYE SMITH, _Scripture and Geology_, 5th Ed. p. 376. [47] "One of the laminated formations [in Auvergne] may be said to furnish a chronometer for itself. It consists of sixty feet of siliceous and calcareous deposits, each as thin as pasteboard, and bearing upon their separating surfaces the stems and seed-vessels of small water-plants in infinite numbers; and countless multitudes of minute shells, resembling some species of our common snail-shells. These layers have been formed with evident regularity, and to each of them we may reasonably assign the term of one season, that is a year. Now thirty of such layers frequently do not exceed one inch in thickness. Let us average them at twenty-five. The thickness of the stratum is at least sixty feet; and thus we gain, for the whole of this formation alone, eighteen thousand years."--DR. J. P. SMITH, _Scripture and Geology_, 5th Edition, p. 137. [48] "This fact has now been verified in almost all parts of the globe, and has led to a conviction that at successive periods of the past the same area of land and water has been inhabited by species of animals and plants as distinct as those which now people the antipodes, or which now co-exist in the arctic, temperate, and tropical zones. It appears that from the remotest periods there has been ever a coming in of new organic forms, and an extinction of those which pre-existed on the earth; some species having endured for a longer, others for a shorter time; but none having ever re-appeared, after once dying out."--LYELL'S _Elements of Geology_, p. 275. [49] J. Pye Smith, Scripture and Geology, 5th Ed., p. 69. [50] In Dr. Pye Smith's Scripture and Geology, p. 382, (Ed. 1855.) [51] I would venture respectfully to suggest that the following argument by Mr. Babbage is vitiated throughout by a confounding of the phenomena observed with the conclusions inferred from them. "What, then, have those accomplished, who have restricted the Mosaic account of the creation to that diminutive period, which is, as it were, but a span in the duration of the earth's existence, and who have imprudently rejected _the testimony of the senses_, when opposed to their philological criticisms? The very arguments which Protestants have opposed to the doctrine of transubstantiation, would, if their view of the case were correct, be equally irresistible against the Book of Genesis. But let us consider what would be the conclusion of any reasonable being in a parallel case. Let us imagine a manuscript written three thousand years ago, and professing to be a revelation from the Deity, in which it was stated that the colour of the paper of the very book now in the reader's hands is _black_, and that the colour of the ink in the characters which he is now reading is _white_. With that reasonable doubt of his own individual faculties which would become the inquirer into the truth of a statement said to be derived from so high an origin, he would ask all those around him, whether to their senses the paper appeared to be _black_, and the ink to be _white_. If he found the senses of other individuals agree with his own, then he would undoubtedly pronounce the alleged revelation a forgery, and those who propounded it to be either deceived or deceivers."--_Ninth Bridgewater Treatise_, p. 68. [52] Dr. Pye Smith calls the hypothesis of progressive development "the crude impertinence of a few foreign sophists,"--and he states as a fact, "that all the great geologists repudiate such a notion with abhorrence, and give physical evidence of its falsehood."--_Scripture and Geology_, (5th Ed.) p. 420. See also Professor Owen in "Rep. Brit Assoc." 1842; Professor Sedgwick, in "Discourse on Stud. of Camb.;" Professor Whewell, in "Hist. of Inductive Sciences;" Professor Ansted, in "Anc. World;" &c. [53] Wallace's "Palms of the Amazon," p. 35. [54] Roxburgh. [55] Rumph, v. 100. [56] My observations rest on the fine specimen of this plant preserved in the British Museum. Dr. Harvey, however, says, "The growth of the trunk in _Kingia_ is very slow, and a specimen about ten feet high may probably be some hundreds of years old." Report of Dubl. Univ. Zool. and Bot. Assoc. for Feb. 25, 1857. See the note _infra_ on page 188. [57] Gaudichaud: Recherches Gén. sur l'Organographie, p. 129. [58] On the development of _Loranthus_, &c. Linn. Tr. xviii p. 71, (_abridged_). [59] "Each and every plant is at first a cell."--"New cells can never be formed externally to, but only within, other cells already formed." (A. Braun, on the Veg. Indiv.) "The process of the propagation of cells, by the formation of new cells in their interior, is an universal law in the vegetable kingdom." (Schleiden; Grundzüge). "Cell-formation in plants takes place only in the cavities of older cells." (Mohl, on the Veg. Cell) [60] See Von Martius, on the Brazilian Locusts. [61] The origin of coral-stocks is minutely described by Ehrenberg, in the Abhandl. for 1832, where he makes the following remarks:--"The coral mass is neither a mere structure composed of many animals arbitrarily conjoined, as Ellis supposed; nor one single animal with many heads, or with simple furcations, as Cavolini maintained; nor a vegetable stem with animal flowers, as Linnæus expressed it; it is a body of families, a _living_ tree of consanguinity; the single animals belonging to it, and continually developing _upon the primary ancestor_, are entirely isolated within themselves, and capable of complete independence, _although unable to achieve it_." [62] This is not quite in accord with Lamouroux's account; but it is more consistent with what we know of polype-growth. [63] We lack precise data on which to found conclusions as to the actual rate of growth of many animals. Sir John Dalyell's famous Actinia, now in the possession of Dr. Fleming, affords us a proof that the Zoophytes are long-lived, and slow in attaining maturity. It will be readily seen, however, that the argument in the text does not depend on the actual period evolved. The lapse of _a_ period of time, no matter how long, is the only essential point. [64] "All the component cells of any one organism may be considered as the descendants of the primordial cell in which it originated." (_Dr. Carpenter_; Comp. Physiol.; p. 396. 4th Ed.) [65] I conclude so; because I have kept specimens of _Echinus_, not full grown, in healthy condition, for nearly a year, without any perceptible increase in their dimensions. [66] I am not aware that this stage of the Entozoon has been actually observed; but from what we know of its previous and subsequent history, the correctness of the statement in the text will scarcely be disputed. (See Prof. Owen: Comp. Anat. of Inverteb. Ed. 2. p. 74.) [67] See Notes to "Marmion." [68] Report on Brit. Annelida, p. 194. [69] We have no direct observations, that I am aware of, on the larval state of the African _Goliathi_; but their near ally, the _Cetonia aurata_ of Europe, passes four years in the grub condition, as does also the _Melolontha vulgaris_, another lamellicorn beetle. The _Lucanus cervus_, or Stag-beetle, continues a larva for six years. [70] Fabre; Ann. d. Sci. Nat.; iii. 1855. [71] _B. splendida_, has been ascertained to have existed, as an inmate of the wood of a table, for _more than twenty_ years. (Linn. Trans.; x. 399.) [72] The rate of increase in dimensions shown by specimens of this species, now so frequently kept in Aquaria, warrants this assertion; though _how many_ years a Crab takes to attain adult size, no exact observations, so far as I know, testify. [73] The exuvia of the cirri are sloughed from the _Balanidæ_ about every week in summer; and perhaps this process is coetaneous with an addition to the valves. [74] Mr. Broderip supposes it to have had the power of swimming freely, and of seeking its future habitation, _as a bivalve_; but Lovèn had not then made known to us the embryogeny and metamorphosis of the _Conchifera_. It is much more probable that the case is as I have ventured to assume in the text. [75] Bennett. [76] Rumphius. [77] The periodical formation of these septa in the progress of growth, is analogous to that of the projecting external plates in the Wendletrap, and of the rows of spines in the _Murex_; but those external processes consist of the opake calcareous layer of the shell, whilst the internal processes in the _Nautilus_ consist of the nacreous layer, like the septa in the _Turritella_. Thus the embryo _Nautilus_ at first inhabits a simple shell, like that of most univalve Mollusca, and manifests, according to the usual law, the general type at the early stage of its existence; although it soon begins, and apparently before having quitted the ovum, to take on the special form.--Prof. Owen's _Lect. on Invertebrate Anim._ p. 593, 2d Ed. [78] Woodward's "Manual of the Mollusca," p. 83. [79] Carpenter, on the Microscope, &c., p. 602. [80] Grant's Comp. Anat., 53. [81] See Jones's General Outline, p. 506. (Ed. 1841.) [82] Such is the common statement. Dr. Harlan, however, observes that "the rattle is cast annually [with the sloughed skin], and, _consequently_, no inference as to the age of the animal can be drawn from the number of pieces which compose the rattles." (_Journ. Acad. Nat. Sci._; v. 368.) I confess this appears to me to be a _non sequitur_; for is it not quite possible that one may be added to the _number_ annually, without involving the actual perpetuity of the preceding ones? It is evident that the increase must take place at some time or other, and it seems to me more likely to occur at the sloughing of the skin, that is, annually, than either oftener or seldomer. [83] Martin "On the Horse," p. 111. [84] Professor Owen's "Odontography:"--to which splendid work I am indebted, for the engravings of these skulls. [85] Brewster's Edinburgh Encyclopædia. [86] Owen's Odontogr. p. 631. [87] Penny Cyclopædia; _art._ BONE. [88] Dr. Carpenter's Human Physiol. p. 916. (Ed. 1855.) [89] Sir Thomas Browne, indeed, denies Adam a navel; I presume, however, physiologists will rather take my view. Sir Thomas did not know that the prochronism which he thought absurd pervaded every part of organic structure. The following is his verdict:-- "Another Mistake there may be in the Picture of our first Parents, who after the manner of theyre Posteritie are bothe delineated with a Navill: and this is observable not only in ordinarie and stayned peeces, but in the Authenticke Draughts of Vrbin, Angelo, and others. Which, notwythstandynge, cannot be allowed, except wee impute that vnto the first Cause, which we impose not on the second; or what wee deny vnto Nature, wee impute vnto Naturity it selfe; that is, that in the first and moste accomplyshed Peece, the Creator affected Superfluities, or ordayned Parts withoute all Vse or Offyce."--_Pseudodoxia Epidemica_, lib. v.; cap. v. [90] Blackwood, in an excellent article on Johnston's _Physical Geography_ (April, 1849), says:--"Adam _must_ have been created in the full possession of manhood; for if he had been formed an infant, he must have perished through mere helplessness. When God looked on this world, and pronounced all to be 'very good,'--which implies the completion of his purpose, and the perfection of his work--is it possible to conceive that he looked only on the germs of production, on plains covered with eggs, or seas filled with spawn, or forests still buried in the capsules of seeds; on a creation utterly shapeless, lifeless and silent, instead of the myriads of delighted existence, all enjoying the first sense of being?" And an eminent Geologist considers the position indisputable, as regards man:--"To the slightest rational consideration it must be evident, that the first human pair were created in the perfection of their bodily organs and mental powers."--(Dr. J. P. Smith; "Script. and Geol.;" 219.) [91] Gen. i. 12, 21, 26, 27. [92] Penny Cyclop.; _art._ ARACHIS. [93] Linn. Trans. iii. 23. [94] Introd. to Entom.; Lett. xi. § 2. [95] Jones; Nat. Hist. Anim.; ii. 151. [96] Cf. Mr. Lubbock (Proc. Roy. Soc. viii. 354), with Dr. Baird (Brit Entomostr. p. 82). [97] Dr. Carpenter: Comp. Phys.; p. 615. [98] Dr. Alex. Braun, "On the Veget. Individual." (Ann. N. H. Nov. 1855.) [99] It may be objected that _Elephas primigenius_ is absolutely distinct from _E. Indicus_. I answer, Yes, _specifically_ distinct; and so am I distinct from my father,--_individually_ distinct. But as individual distinctness does not preclude the individual from being the exponent of a circular revolution in the life-history of the species, so specific distinctness may not preclude the species from being the exponent of a circular revolution in some higher, unnamed, life-history. [100] "We may assert of the individual, as well as of the species, that it completes the cycle of its existence in a succession of subordinate generations; while, on the other hand, we may affirm of the species, that, like the individual, it exhibits a determinate cycle of development." "The species itself may be regarded as an inferior 'momentum' of a still more comprehensive cycle of development."--_Dr. A. Braun_, "_On the Vegetable Individual._" "The species is an individual of a higher rank."--_Link: Elements of Botanical Science_, vi. 11. "Species, like individuals, have a certain limited term of existence. It is the fact, that, _according to some general law_, species of animals are introduced, last for a limited period, and are then succeeded by others performing the same office."--_Ansted's Ancient World_, 52, 54. [101] "The unity of the plan of organization, and the regular succession of animal forms, point out a _beginning_ of this great kingdom on the surface of our globe, although the earliest stages of its development may now be effaced: and the continuity of the series though all geological epochs, and the _gradual transitions_ which _connect_ the species of one formation with those of the next in succession, distinctly indicate that they form _the parts of one creation_, and not the heterogeneous remnants of successive kingdoms begun and destroyed: so that, while they present the best records of the changes which the surface of the globe has undergone, they likewise afford the best testimony of the recent origin of the present crust of our planet, and of all its organic inhabitants."--_Dr. Grant, in Br. Sci. Annual for 1839._ [102] Dr. Harris has the following observations:-- "Why might not God have created the crust of the earth, just as it is, with all its numberless stratifications, and diversified formations, complete? And the analogy for such an exercise of creative power is supposed to be found in the creation of Adam, not as an infant, but as _an adult_; and in the production of the _full-sized_ trees of Eden. To which the reply is direct: the maturity of the first man, and of the objects around him, could not deceive him by implying that they had slowly grown to that state. His first knowledge was the knowledge of the contrary. He lived, partly, in order to proclaim the fact of his creation. And, could his own body, or any of the objects created at the same time, have been subjected to a physiological examination, they would, no doubt, have been found to indicate their miraculous production in their very destitution of all the traces of an early growth; whereas the shell of the earth is a crowded storehouse of evidence of its gradual formation. So that the question, expressed in other language, amounts to this: Might not the God of infinite truth have enclosed in the earth, at its creation, evidence of its having existed ages before its actual production? Of course, the objector would disavow such a sentiment. But such appears to be the real import of the objection; and, as such, it involves its own refutation."--_Pre-Adamite Earth_, p. 83. Now this reasoning appeared, doubtless, very triumphant to the worthy Doctor: and yet a very little acquaintance with physiology would have taught him that he was enunciating an absurdity. The very supposition which he considers as self-refuting, is an indubitable physiological fact. I have abundantly shown, in the text, that the _cells which compose_ the tree or the animal are as undeniable evidences of past processes as the concentric cylinders of timber, or the superposed layers of bone and scale. [103] I here assume the life-history of the globe to be represented by a straight line, because I cannot _prove_ it to be a circle. I cannot even _imagine_ its circularity. I do not mean the possibility;--I can imagine _that_: but the _mode_ I cannot conceive. This, however, does not disprove the possibility. If man's science extended not beyond the accumulated observations of his own life, he would probably be quite incompetent to conceive how the life-history of such a tree as the Oak could be a circle; if he had never seen more than one individual, which was a tree when he was born, and continued to flourish till his death. [104] The existence of Coprolites--the fossilized excrement of animals--has been considered a more than ordinarily triumphant proof of real pre-existence. Would it not be closely parallel with the presence of fæces in the intestines of an animal at the moment of creation? Yet this appears to me demonstrable. It may seem at first sight ridiculous, and will probably be represented so; but truth is truth. I have already proved that blood must have been in the arteries and veins of the newly-created Man (_vide_ p. 276, _supra_), and that blood presupposes chyle and chyme; but what became of the indigestible residuum of the chyme, when the chyle was separated from it? Would it not, as a matter of course, be found in the intestines? If the principle is true, that the created organism was exactly what it would have been had it reached that condition by the ordinary course of nature, then fæcal residua must have been in the intestines as certainly as chyle in the lacteals, or blood in the capillaries. [105] _Blackwood_; April, 1849; p. 412. [106] Strictly speaking, the current is a lagging behind of the water, which cannot keep pace with the speed communicated to the solid crust of the globe at its equatorial regions. The trade-wind is owing to the same cause. [107] Philos. Trans. for 1802; p. 498. [108] Beitrage, p. 152. [109] Dr. A. Braun, On the Veg. Indiv. [110] See _ante_, p. 233. [111] Fauna Littor. Norveg.; i. 47. * * * * * MARINE NATURAL HISTORY CLASS. In the summer of 1855, I met, at Ilfracombe, on the coast of North Devon, a small party of ladies and gentlemen, who formed themselves into a Class for the study of Marine Natural History. There was much to be done in the way of collecting, much to be learned in the way of study. Not a few species of interest, and some rarities, fell under our notice, scattered as we were over the rocks, and peeping into the pools, almost every day for a month. Then the prizes were to be brought home, and kept in little Aquariums for the study of their habits, their beauties to be investigated by the pocket-lens, and the minuter kinds to be examined under the microscope. An hour or two was spent on the shore every day on which the tide and the weather were suitable; and, when otherwise, the occupation was varied by an indoors' lesson, on identifying and comparing the characters of the animals obtained, the specimens themselves affording illustrations. Thus the two great desiderata of young naturalists were attained simultaneously; they learned at the same time how to collect, and how to determine the names and the zoological relations of the specimens when found. A little also was effected in the way of dredging the sea-bottom, and in surface-fishing for Medusæ, &c.; but our chief attention was directed to shore-collecting. Altogether, the experiment was found so agreeable, that I propose to repeat it by forming a similar party every year, if spared, at some suitable part of the coast. Such ladies or gentlemen as may wish to join the Class should give in their names to me, early in the summer; and any preliminary inquiries about plans, terms, &c. shall meet the requisite attention. P. H. GOSSE. MARYCHURCH, TORQUAY, _Oct. 1857_. 
31316	----	Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 31316-h.htm or 31316-h.zip: (http://www.gutenberg.org/files/31316/31316-h/31316-h.htm) or (http://www.gutenberg.org/files/31316/31316-h.zip) The Cambridge Manuals of Science and Literature THE COMING OF EVOLUTION Cambridge University Press London: Fetter Lane, E.C. C. F. Clay, Manager [Illustration] Edinburgh: 100, Princes Street London: H. K. Lewis, 136, Gower Street, W.C. Berlin: A. Asher and Co. Leipzig: F. A. Brockhaus New York: G. P. Putnam's Sons Bombay and Calcutta: Macmillan and Co., Ltd. All rights reserved [Illustration: Charles Darwin] THE COMING OF EVOLUTION The Story of a Great Revolution in Science by JOHN W. JUDD C.B., LL.D., F.R.S. Formerly Professor of Geology and Dean of the Royal College of Science Cambridge: at the University Press 1910 Cambridge: Printed by John Clay, M.A. At the University Press _With the exception of the coat of arms at the foot, the design on the title page is a reproduction of one used by the earliest known Cambridge printer, John Siberch, 1521_ CONTENTS CHAP. PAGE I. Introductory 1 II. Origin of the Idea of Evolution 5 III. The Development of the Idea of Evolution to the Inorganic World 14 IV. The Triumph of Catastrophism over Evolution 20 V. The Revolt of Scrope and Lyell against Catastrophism 33 VI. _The Principles of Geology_ 55 VII. The Influence of Lyell's Works 68 VIII. Early Attempts to establish the Doctrine of Evolution for the Organic World 82 IX. Darwin and Wallace: The Theory of Natural Selection 95 X. _The Origin of Species_ 115 XI. The Influence of Darwin's Works 136 XII. The Place of Lyell and Darwin in History 149 Notes 160 Index 165 PLATES Charles Darwin _Frontispiece_ G. Poulett Scrope _to face p. 35_ Charles Lyell " " 41 Alfred R. Wallace " " 110 CHAPTER I INTRODUCTORY When the history of the Nineteenth Century--'the Wonderful Century,' as it has, not inaptly, been called--comes to be written, a foremost place must be assigned to that great movement by which evolution has become the dominant factor in scientific progress, while its influence has been felt in every sphere of human speculation and effort. At the beginning of the Century, the few who ventured to entertain evolutionary ideas were regarded by their scientific contemporaries, as wild visionaries or harmless 'cranks'--by the world at large, as ignorant 'quacks' or 'designing atheists.' At the end of the Century, evolution had not only become the guiding principle of naturalists, but had profoundly influenced every branch of physical science; at the same time, suggesting new trains of thought and permeating the language of philologists, historians, sociologists, politicians--and even of theologians. How has this revolution in thought--the greatest which has occurred in modern times--been brought about? What manner of men were they who were the leaders in this great movement? What the influences that led them to discard the old views and adopt new ones? And, under what circumstances were they able to produce the works which so profoundly affected the opinions of the day? These are the questions with which I propose to deal in the following pages. It has been my own rare good fortune to have enjoyed the friendship of all the great leaders in this important movement--of Huxley, Hooker, Scrope, Wallace, Lyell and Darwin--and, with some of them, I was long on terms of affectionate intimacy. From their own lips I have learned of incidents, and listened to anecdotes, bearing on the events of a memorable past. Would that I could hope to bring before my readers, in all their nobility, a vivid picture of the characteristics of the men to whom science and the world owe so much! For it is not only by their intellectual greatness that we are impressed. Every man of science is proud, and justly proud, of the grandeur of character, the unexampled generosity, the modesty and simplicity which distinguished these pioneers in a great cause. It is unfortunately true, that the votaries of science--like the cultivators of art and literature--have sometimes so far forgotten their high vocation, as to have been more careful about the priority of their personal claims than of the purity of their own motives--they have sometimes, it must be sadly admitted, allowed self-interest to obscure the interests of science. But in the story we have to relate there are no 'regrettable incidents' to be deplored; never has there occurred any event that marred the harmony in this band of fellow-workers, striving towards a great ideal. So noble, indeed, was the great central figure--Charles Darwin--that his senior Lyell and all his juniors were bound to him by the strongest ties of admiration, respect and affection; while he, in his graceful modesty, thought more of them than of himself, of the results of their labours rather than of his own great achievement. It is not, as sometimes suggested, the striking out of new ideas which is of the greatest importance in the history of science, but rather the accumulation of observations and experiments, the reasonings based upon these, and the writings in which facts and reasonings are presented to the world--by which a merely suggestive hypothesis becomes a vivifying theory--that really count in making history. Talking with Matthew Arnold in 1871, he laughingly remarked to me 'I cannot understand why you scientific people make such a fuss about Darwin. Why it's all in Lucretius!' On my replying, 'Yes! Lucretius guessed what Darwin proved,' he mischievously rejoined 'Ah! that only shows how much greater Lucretius really was,--for he divined a truth, which Darwin spent a life of labour in groping for.' Mr Alfred Russel Wallace has so well and clearly set forth the essential difference between the points of view of the cultivators of literature and science in this matter, that I cannot do better than to quote his words. They are as follows:-- 'I have long since come to see that no one deserves either praise or blame for the _ideas_ that come to him, but only for the _actions_ resulting therefrom. Ideas and beliefs are certainly not voluntary acts. They come to us--we hardly know _how_ or _whence_, and once they have got possession of us we cannot reject them or change them at will. It is for the common good that the promulgation of ideas should be free--uninfluenced by either praise or blame, reward or punishment.' 'But the _actions_ which result from our ideas may properly be so treated, because it is only by patient thought and work that new ideas, if good and true, become adopted and utilized; while, if untrue or if not adequately presented to the world, they are rejected or forgotten[1].'[A] _Ideas_ of Evolution, both in the Organic and the Inorganic world, existed but remained barren for thousands of years. Yet by the labours of a band of workers in last century, these ideas, which were but the dreams of poets and the guesses of philosophers, came to be the accepted creed of working naturalists, while they have profoundly affected thought and language in every branch of human enterprise. [A] For References see the end of the volume. CHAPTER II ORIGIN OF THE IDEA OF EVOLUTION In all ages, and in all parts of the world, we find that primitive man has delighted in speculating on the birth of the world in which he lives, on the origin of the living things that surround him, and especially on the beginnings of the race of beings to which he himself belongs. In a recent very interesting essay[2], the author of _The Golden Bough_ has collected, from the records of tradition, history and travel, a valuable mass of evidence concerning the legends which have grown out of these speculations. Myths of this kind would appear to fall into two categories, each of which may not improbably be associated with the different pursuits followed by the uncivilised races of mankind. Tillers of the soil, impressed as they must have been by the great annual miracle of the outburst of vegetable life as spring returns, naturally adopted one of these lines of speculation. From the dead, bare ground they witnessed the upspringing of all the wondrous beauty of the plant-world, and, in their ignorance of the chemistry of vegetable life, they imagined that the herbs, shrubs and trees are all alike built up out of the materials contained in the soil from which they grow. The recognition of the fact that animals feed on plants, or on one another, led to the obvious conclusion that the _ultimate_ materials of animal, as well as of vegetable, structures were to be sought for in the soil. And this view was confirmed by the fact that, when life ceases in plants or animals, all alike are reduced to 'dust' and again become a part of the soil--returning 'earth to earth.' In groping therefore for an explanation of the origin of living things, what could be more natural than the supposition that the first plants and animals--like those now surrounding us--were made and fashioned from the soil, dust or earth--all had been 'clay in the hands of a potter.' The widely diffused notion that man himself must have been moulded out of _red_ clay is probably accounted for by the colour of our internal organs. Thus originated a large class of legendary stories, many of them of a very grotesque character. Even in many mediaeval sculptures, in this country and on the continent, the Deity is represented as moulding with his hands the semblance of a human figure out of a shapeless lump of clay. But among the primitive hunters and herdsmen a very different line of speculation appears to have originated, for by their occupations they were continually brought into contact with an entirely different class of phenomena. They could not but notice that the creatures which they hunted or tended, and slew, presented marked resemblances to themselves--in their structures, their functions, their diseases, their dispositions, and their habits. When dogs and horses became the servants and companions of men, and when various beasts and birds came to be kept as pets, the mental and even the moral processes characterising the intelligence of these animals must have been seen by their masters to be identical in kind with those of their own minds. Do we not even at the present day compare human characteristics with those of animals, the courage of the lion, the cunning of the fox, the fidelity of the dog, and the parental affection of the bird? And the men, who depended for their very existence on studying the ways of various animals, could not have been less impressed by these qualities than are we. Mr Frazer has shown how, from such considerations, the legends concerning the relations of certain tribes of men with particular species of animals have arisen, and thus the cults of 'sacred animals' and of 'totemism' have been gradually developed. From comparisons of human courage, sagacity, swiftness, strength or perseverance, with similar qualities displayed by certain animals, it was an easy transition to the idea that such characteristics were derived by inheritance. In the absence of any exact knowledge of anatomy and physiology, the resemblances of animals to themselves would quite outbulk the differences in the eyes of primitive men, and the idea of close relationship in blood does not appear to have been regarded with distaste. In their origin and in their destiny, no distinction was drawn between man and what we now designate as the 'lower' animals. Primitive man not only feels no repugnance to such kinship:-- 'But thinks, admitted to that equal sky, His faithful dog shall hear him company[3].' It should perhaps be remembered, too, that, in the breeding of domestic animals, the great facts of heredity and variation could not fail to have been noticed, and must have given rise to reflection and speculation. The selection of the best animals for breeding purposes, and the consequent improvement of their stock, may well have suggested the transmutation of one kind of animal into a different kind, just as the crossing of different kinds of animals seems to have suggested the possible existence of centaurs, griffins and other monstrous forms. How early the principles of variation and heredity, and even the possibility of improving breeds by selection, must have been appreciated by early men is illustrated by the old story of the way in which the wily Jacob made an attempt--however futile were the means he adopted--to cheat his employer Laban[4]. Yet, in spite of observed tendencies to variation among animals and plants, early man must have been convinced of the existence of distinct kinds ('species') in both the vegetable and animal worlds; he recognised that plants of definite kinds yielded particular fruits, and that different kinds of animals did not breed promiscuously with one another, but that, pairing each with its own kind, all gave rise to like offspring, and thus arose the idea of distinct 'species' of plants and animals. It must be remembered, however, that for a long time 'the world' was believed to be limited to a few districts surrounding the Eastern Mediterranean, and the kinds or 'species' of animals and plants were supposed to number a few scores or at most hundreds. This being the case, the sudden stocking of 'the world' with its complement of animals and plants would be thought a comparatively simple operation, and the violent destruction of the whole a scarcely serious result. Even the possibility of the preservation of pairs of all the different species, in a ship of moderate dimensions, was one that was easily entertained and was not calculated to awaken either surprise or incredulity. But how different is the problem as it now presents itself to us! In the year 1900 Professor S. H. Vines of Oxford estimated that the number of 'species' of plants that have been described could be little short of 200,000, and that future studies, especially of the lower microscopic forms, would probably bring that number up to 300,000[5]. Last year, Mr A. E. Shipley of Cambridge, basing his estimate on the earlier one of Dr Günther, came to the conclusion that the number of described animals must also exceed 300,000[6]. On the lowest estimate then we must place the number of known species of plants and animals, living on the globe, as 600,000! And if we consider the numbers of new forms of plants and animals that every year are being described by naturalists--about 1500 plants and 1200 animals--if we take into account the inaccessible or as yet unvisited portions of the earth's surface, the very imperfectly known depths of the sea, and, in addition to these, the almost infinite varieties of minute and microscopic forms, I think every competent judge would consider _a million_ as being probably an estimate below, rather than above, the number of 'species' now existing on the earth! While some of these species are very widely distributed over the earth's surface, or in the waters of the oceans, seas, lakes and rivers, there are others which are as strikingly limited in their range. Many of the myriad forms of insect-life pass their whole existence, and are dependent for food, on a particular species of plant. Not a few animals and plants are parasitical, and can only live in the interior or on the outside of other plants and animals. It will be seen from these considerations that in attempting to decide between the two hypotheses of the _origin_ of species--the only ones ever suggested--namely the fashioning of them out of dead matter, or their descent with modification from pre-existing forms, we are dealing with a problem of much greater complexity than could possibly have been imagined by the early speculators on the subject. The two strongly contrasted hypotheses to which we have referred are often spoken of as 'creation' and 'evolution.' But this is an altogether illegitimate use of these terms. By _whatever method_ species of plants or animals come into existence, they may be rightly said to be 'created.' We speak of the existing plants and animals as having been created, although we well know them to have been 'evolved' from seeds, eggs and other 'germs'--and indeed from those excessively minute and simple structures known as 'cells.' Lyell and Darwin, as we shall presently see, though they were firmly convinced that species of plants and animals were slowly developed and not suddenly manufactured, wrote constantly and correctly of the 'creation' of new forms of life. The idea of 'descent with modification,' derived from the early speculations of hunters and herdsmen, is really a much nobler and more beautiful conception of 'creation' than that of the 'fashioning out of clay,' which commended itself to the primitive agriculturalists. Lyell writing to his friend John Herschel, who like himself believed in the derivation of new species from pre-existing ones by the action of secondary causes, wrote in 1836:-- When I first came to the notion, ... of a succession of extinction of species, and creation of new ones, going on perpetually now, and through an indefinite period of the past, and to continue for ages to come, all in accommodation to the changes which must continue in the inanimate and habitable earth, the idea struck me as the grandest which I had ever conceived, so far as regards the attributes of the Presiding Mind[7].' And Darwin concludes his presentment of the doctrine of evolution in the _Origin of Species_ in 1859 with the following sentence:-- 'There is a grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved[8].' Compare with these suggestions the ideas embodied in the following lines--ideas of which the crudeness cannot be concealed by all the witchery of Milton's immortal verse:-- 'The Earth obey'd, and straight, Op'ning her fertile womb, teem'd at a birth Innumerous living creatures, perfect forms, Limb'd and full grown. Out of the ground up rose As from his lair, the wild beast, where he wons In forest wild, in thicket, brake, or den; Among the trees they rose, they walk'd; The cattle in the fields and meadows green: Those rare and solitary, these in flocks Pasturing at once, and in broad herds upsprung. The grassy clods now calv'd; now half appear'd The tawny lion, pawing to get free His hinder parts, then springs, as broke from bonds, And rampant shakes his brinded mane[9].' Can anyone doubt for a moment which is the grander view of 'Creation'--that embodied in Darwin's prose, or the one so strikingly pictured in Milton's poetry? We see then that the two ideas of the method of creation, dimly perceived by early man, have at last found clear and definite expression from these two authors--Milton and Darwin. It is a singular coincidence that these two great exponents of the rival hypotheses were both students in the same University of Cambridge and indeed resided in the same foundation--and that not one of the largest of that University--namely Christ's College. CHAPTER III THE DEVELOPMENT OF THE IDEA OF EVOLUTION TO THE INORGANIC WORLD We have seen in the preceding chapter that, with respect to the origin of plants and animals--including man himself--two very distinct lines of speculation have arisen; these two lines of thought may be expressed by the terms 'manufacture'--literally making by hand, and 'development' or 'evolution,'--a gradual unfolding from simpler to more complex forms. Now with respect to the _inorganic_ world two parallel hypotheses of 'creation' have arisen, like those relating to _organic_ nature; but in the former case the determining factor in the choice of ideas has been, not the avocations of the primitive peoples, but the nature of their surroundings. The dwellers in the valleys of the Euphrates and Tigris could not but be impressed by the great and destructive floods to which those regions were subject; and the inhabitants of the shores and islands of the Aegean Sea, and of the Italian peninsula, were equally conversant with the devastations wrought by volcanic outbursts and earthquake shocks. As great districts were seen to be depopulated by these catastrophies, might not some even more violent cataclysm of the same kind actually destroy all mankind, with the animals and plants, in the comparatively small area then known as 'the world'? The great flood, of which all these nations appear to have retained traditions, was regarded as only the last of such destructive cataclysms; and, in this way, there originated the myth of successive destructions of the face of the earth, each followed by the creation of new stocks of plants and animals. This is the doctrine now known as 'Catastrophism,' which we find prevalent in the earliest traditions and writings of India, Babylonia, Syria and Greece. But in ancient Egypt quite another class of phenomena was conspicuously presented to the early philosophers of the country. Instead of sudden floods and terrible displays of volcanic and earthquake violence, they witnessed the annual gentle rise and overflowings of their grand river, with its beneficent heritage of new soil; and they soon learned to recognise that Egypt itself--so far as the delta was concerned--was 'the gift of the Nile.' From the contemplation of these phenomena, the Egyptian sages were gradually led to entertain the idea that all the features of the earth--as they knew it--might have been similarly produced through the slow and constant action of the causes now seen in operation around them. This idea was incorporated in a myth, which was suggested by the slow and gradual transformation of an egg into a perfect, growing organism. The birth of the world was pictured as an act of incubation, and male and female deities were invented to play the part of parents to the infant world. By Pythagoras, who resided for more than twenty years in Egypt, these ideas were introduced to the Greek philosophers, and from that time 'Catastrophism' found a rival in the new doctrine which we shall see has been designated under the names of 'Continuity,' 'Uniformitarianism' or 'Evolution.' How, from the first crude notions of evolution, successive thinkers developed more just and noble conceptions on the subject, has been admirably shown by Professor Osborn in his _From the Greeks to Darwin_ and by Mr Clodd in his _Pioneers of Evolution_. Poets, from Empedocles and Lucretius to Goethe and Tennyson, have sought in their verses to illustrate the beauty of evolutionary ideas; and philosophers, from Aristotle and Strabo to Kant and Herbert Spencer, have recognised the principle of evolution as harmonising with, and growing out of, the highest conceptions of science. Yet it was not till the Nineteenth Century that any serious attempts were made to establish the hypothesis of evolution as a definite theory, based on sound reasoning from careful observation. It is true that there were men, in advance of their age, who in some cases anticipated to a certain extent this work of establishing the doctrine of evolution on a firm foundation. Thus in Italy, the earliest home of so many sciences, a Carmelite friar, Generelli, reasoning on observations made by his compatriots Fracastoro and Leonardo da Vinci in the Sixteenth Century, Steno and Scilla in the Seventeenth, and Lazzaro Moro and Marsilli in the Eighteenth Century, laid the foundations of a rational system of geology in a work published in 1749 which was characterised alike by courage and eloquence. In France, the illustrious Nicolas Desmarest, from his study of the classical region of the Auvergne, was able to show, in 1777, how the river valleys of that district had been carved out by the rivers that flow in them. Nor were there wanting geologists with similar previsions in Germany and Switzerland. But none of these early exponents of geological theory came so near to anticipating the work of the Nineteenth Century as did the illustrious James Hutton, whose 'Theory of the Earth,' a first sketch of which was published in 1785, was a splendid exposition of evolution as applied to the inorganic world. Unfortunately, Hutton's theory was linked to the extravagancies of what was known at that day as 'Vulcanism' or 'Plutonism,' in contradistinction to the 'Neptunism' of Werner. Hutton, while rejecting the Wernerian notion of "the aqueous precipitation of basalt," maintained the equally fanciful idea that the consolidation of all strata--clays, sandstones, conglomerates, limestones and even rock-salt--must be ascribed to the action of heat, and that even the formation of chalk-flints and the silicification of fossil wood were due to the injection of molten silica! What was still more unfortunate in Hutton's case was that, in his enthusiasm, he used expressions which led to his being charged with heresy and even with being an enemy of religion. His writings were further so obscure in style as often to lead to misconception as to their true meaning, while his great work--so far as the fragment which was published goes--contained few records of original observations on which his theory was based. Dr Fitton has pointed out very striking coincidences between the writings of Generelli and those of Hutton, and has suggested that the latter may have derived his views from the eloquent Italian friar[10]. But for this suggestion, I think that there is no real foundation. Darwin and Wallace, as we shall see later, were quite unconscious of their having been forestalled in the theory of Natural Selection by Dr Wells and Patrick Matthew; and Hutton, like his successor Lyell, in all probability arrived, quite independently, and by different lines of reasoning, at conclusions identical with those of Generelli and Desmarest. Although, as we shall see, Hutton failed to greatly influence the scientific thought of his day, yet all will now agree with Lyell that 'Hutton laboured to give fixed principles to geology, as Newton had succeeded in doing to astronomy[11]'; and with Zittel that '_Hutton's Theory of the Earth_ is one of the masterpieces in the history of geology[12].' CHAPTER IV THE TRIUMPH OF CATASTROPHISM OVER EVOLUTION There is no fact in the history of science which is more certain than that those great pioneers of Evolution in the Inorganic world--Generelli, Desmarest and Hutton--utterly failed to recommend their doctrines to general acceptance; and that, at the beginning of last century, everything in the nature of evolutionary ideas was almost universally discredited--alike by men of science and the world at large. The causes of the neglect and opprobrium which befel all evolutionary teachings are not difficult to discover. The old Greek philosophers saw no more reason to doubt the possibility of creation by evolution, than by direct mechanical means. But, on the revival of learning in Europe, evolution was at once confronted by the cosmogonies of Jewish and Arabian writers, which were incorporated in sacred books; and not only were the ideas of the sudden making and destruction of the world and all things in it regarded as revealed truth, but the periods of time necessary for evolution could not be admitted by those who believed the beginning of the world to have been recent, and its end to be imminent. Thus 'Catastrophic' ideas came to be regarded as _orthodox_, and evolutionary ones as utterly irreligious and damnable. There are few more curious facts in the history of science than the contrast between the reception of the teaching of the Saxon professor Werner, and those of Hutton, the Scotch philosopher, his great rival. While the enthusiastic disciples of the former carried their master's ideas everywhere, acting with missionary zeal and fervour, and teaching his doctrines almost as though they were a divine revelation, the latter, surrounded by a few devoted friends, saw his teachings everywhere received with persistent misrepresentation, theological vituperation or contemptuous neglect. Even in Edinburgh itself, one of Werner's pupils dominated the teaching of the University for half a century, and established a society for the propagation of the views which Hutton so strongly opposed. When it is remembered that Hutton wrote at a time when 'heresy-hunting' in this country had been excited to such a dangerous extent, through the excesses of the French Revolution, that his contemporary, Priestley, had been hounded from his home and country for proclaiming views which at that time were regarded as unscriptural, it becomes less difficult to understand the prejudice that was excited against the gentle and modest philosopher of Edinburgh. We have employed the term 'Catastrophism' to indicate the views which were prevalent at the beginning of last century concerning the origin of the rock-masses of the globe and their fossil contents. These views were that at a number of successive epochs--of which the age of Noah was the latest--great revolutions had taken place on the earth's surface; that during each of these cataclysms all living things were destroyed; and that, after an interval, the world was restocked with fresh assemblages of plants and animals, to be destroyed in turn and entombed in the strata at the next revolution. Whewell, in 1830, contrasted this teaching with that of Hutton and Lyell in the following passage:--'These two opinions will probably for some time divide the geological world into two sects, which may perhaps be designated the "Uniformitarians" and the "Catastrophists." The latter has undoubtedly been of late the prevalent doctrine.' It is interesting to note, as showing the confidence felt in their tenets by the 'Catastrophists' of that day, that Whewell adds 'We conceive that Mr Lyell will find it a harder task than he imagines to overturn the established belief[13]!' Some authors have suggested that the doctrine taught by Generelli, Desmarest and Hutton, and later by Scrope and Lyell, for which Whewell proposed the somewhat cumbrous term 'Uniformitarianism,' but which was perhaps better designated by Grove in 1866 as 'Continuity[14],' was distinct from, and subsidiary to, Evolution--and this view could claim for a time the support of a very great authority. In 1869, Huxley delivered an address to the Geological Society, in which he postulated the existence of 'three more or less contradictory systems of geological thought,' under the names of 'Catastrophism,' 'Uniformitarianism' and 'Evolution.' In this essay, distinguished by all his wonderful lucidity and forceful logic, Huxley sought to establish the position that evolution is a doctrine, distinct from and _in advance of_ that of uniformitarianism, and that Hutton and Playfair--'and to a less extent Lyell'--had acted unwisely in deprecating the extension of Geology into enquiries concerning 'the beginning of things[15].' But there is no doubt that Huxley at a later period was led to qualify, and indeed to largely modify, the views maintained in that address. In a footnote to an essay written in April 1887, he asserts 'What I mean by "evolutionism" is consistent and thoroughgoing uniformitarianism'; and in the same year he wrote in his _Reception of the Origin of Species_[16]: 'Consistent uniformitarianism postulates evolution, as much in the organic as in the inorganic world[17].' It is not difficult to trace the causes of this change in the attitude of mind with which Huxley regarded the doctrine of 'uniformitarianism.' He assures us 'I owe more than I can tell to the careful study of the _Principles of Geology_[18],' and again 'Lyell was for others as for me the chief agent in smoothing the road for Darwin[19].' From the perusal of the letters of Lyell, published in 1881, Huxley learned that the author of the _Principles of Geology_ had, at a very early date, been convinced that evolution was true of the organic as well as of the inorganic world--though he had been unable to accept Lamarckism, or any other hypothesis on the subject that had, up to that time, been suggested. There can be little doubt, however, that a chief influence in bringing about the change in Huxley's views was his intercourse with Darwin--who was, from first to last, an uncompromising 'uniformitarian.' We are fully justified, then, in regarding the teaching of Hutton and Lyell (to which Whewell gave the name of 'uniformitarianism') as being identical with evolution. The cockpit in which the great battle between catastrophism and evolution was fought out, as we shall see in the sequel, was the Geological Society of London, where doughty champions of each of the rival doctrines met in frequent combat and long maintained the struggle for supremacy. Fitton has very truly said that 'the views proposed by Hutton failed to produce general conviction at the time; and several years elapsed before any one showed himself publicly concerned about them, either as an enemy or a friend[20].' Sad is it to relate that, when notice was at last taken of the memoir on the 'Theory of the Earth,' it was by bitter opponents--such 'Philistines' (as Huxley calls them) as Kirwan, De Luc and Williams, who declared the author to be an enemy of religion. Not only did Hutton, unlike the writers of other theories of the earth, omit any statement that his views were based on the Scriptures, but, carried away by the beauty of the system of continuity which he advocated, he wrote enthusiastically 'the result of this physical enquiry is that we find no vestige of a beginning--no prospect of an end[21].' This was unjustly asserted to be equivalent to a declaration that the world had neither beginning nor end; and thus it came about that Wernerism, Neptunism and Catastrophism were long regarded as synonymous with Orthodoxy, while Plutonism and 'Uniformitarianism' were looked upon with aversion and horror as subversive of religion and morality. Almost simultaneously with the foundation of the Wernerian Society of Edinburgh (in 1807) was the establishment in London of the Geological Society. Originating in a dining club of collectors of minerals, the society consisted at first almost exclusively of mineralogists and chemists, including Davy, Wollaston, Sir James Hall, and later, Faraday and Turner. The bitter but barren conflict between the Neptunists and the Plutonists was then at its height, and it was, from the first, agreed in the infant society to confine its work almost entirely to the collection of facts, eschewing theory. During the first decade of its existence, it is true, the chief papers published by the society were on mineralogical questions; but gradually geology began to assert itself. The actual founder and first president of the society, Greenough, had been a pupil of Werner, and used all his great influence to discourage the dissemination of any but Wernerian doctrines--foreign geologists, like Dr Berger, being subsidised to apply the Wernerian classification and principles to the study of British rocks. Thus, in early days, the Geological Society became almost as completely devoted to the teaching of Wernerian doctrines as was the contemporary society in Edinburgh. Dr Buckland used to say that when he joined the Geological Society in 1813, 'it had a very _landed_ manner, and only admitted the professors of geology in Oxford and Cambridge on sufferance.' But, gradually, changes began to be felt in this aristocratic body of exclusive amateurs and wealthy collectors of minerals. William Smith, 'the Father of English Geology'--though he published little and never joined the society--exercised a most important influence on its work. By his maps, and museum of specimens, as well as by his communications, so freely made known, concerning his method of 'identifying strata by their organic remains,' many of the old geologists, who were not aware at the time of the source of their inspiration, were led to adopt entirely new methods of studying the rocks. In this way, the accurate mineralogical and geognostical methods of Werner came to be supplemented by the fruitful labours of the stratigraphical palaeontologist. The new school of geologists included men like William Phillips, Conybeare, Sedgwick, Buckland, De la Beche, Fitton, Mantell, Webster, Lonsdale, Murchison, John Phillips and others, who laid the foundations of British stratigraphical geology. But these great geological pioneers, almost without exception, maintained the Wernerian doctrines and were firm adherents of Catastrophism. The three great leaders--the enthusiastic Buckland, the eloquent Sedgwick, and the indefatigable Conybeare--were clergymen, as were also Whewell and Henslow, and they were all honestly, if mistakenly, convinced that the Huttonian teaching was opposed to the Scriptures and inimical to religion and morality. Buckland at Oxford, and Sedgwick at Cambridge, made geology popular by combining it with equestrian exercise; and Whewell tells us how the eccentric Buckland used to ride forth from the University, with a long cavalcade of mounted students, holding forth with sarcasm and ridicule concerning 'the inadequacy of existing causes[22].' And Sedgwick at Cambridge was no less firmly opposed to evolutionary doctrine, eloquently declaiming at all times against the unscriptural tenets of the Huttonians. I cannot better illustrate the complete neglect at that time by leading geologists in this country of the Huttonian teaching than by pointing to the Report drawn up in 1833, by Conybeare, for the British Association, on 'The Progress, Actual State and Ulterior Prospects of Geological Science[23].' This valuable memoir of 47 pages opens with a sketch of the history of the science, in which the chief Italian, French and German investigators are referred to, but the name of Hutton is not even mentioned! And if positive evidence is required of the contempt which the early geologists felt for Hutton and his teachings, it will be found in the same author's introduction to that classical work, the _Outlines of Geology_ (1822), in which he says of Hutton, after praising his views on granite veins and "trap rocks":-- 'The wildness of many of his theoretical views, however, went far to counterbalance the utility of the additional facts which he collected from observation. He who could perceive in geology nothing but the _ordinary_ operation of actual causes, carried on in the same manner through infinite ages, without the trace of a beginning or the prospect of an end, must have surveyed them through the medium of a preconceived hypothesis alone[24].' John Playfair, the brilliant author of the _Illustrations of the Huttonian Theory_, died in 1819; under happier conditions his able work might have done for Inorganic Evolution what his great master failed to accomplish; but the dead weight of prejudice and the dread of anything that seemed to savour of infidelity was, at the time of the great European struggle against revolutionary France, too great to be removed even by his lucid statements and eloquent advocacy. James Hall and Leonard Horner, two faithful disciples of Hutton, who had joined the infant Geological Society, forsook it early, the former leaving it on account of the quarrel with the Royal Society, the latter retaining his fellowship and interest, but going to live at Edinburgh. Greenough, 'The Objector General,' as he was called, was left, fanatically opposing any attempt to stem the current that had set so strongly in favour of Wernerism and Neptunism, and the Catastrophic doctrines which all thought to be necessary conclusions from them. The great heroic workers of that day--while they were laying well and truly the foundations of historical geology--were, one and all, indifferent to, or violently opposed to, the Huttonian teaching. Neither Fitton nor John Phillips, who at a later date showed sympathy with evolutionary doctrines, were the men to fight the battle of an unpopular cause. Attempts have been made by both Playfair and Fitton to explain how it was that Hutton's teaching failed to arrest the attention it deserved. The former justly asserted that the world was tired of the performances issued under the title of 'theories of the earth'; and that the condensed nature of Hutton's writings, with their 'embarrassment of reasoning and obscurity of style[25]' are largely responsible for the neglect into which they fell. Fitton, in 1839, wrote in the _Edinburgh Review_, 'The original work of Hutton (in two volumes) is in fact so scarce that no very great number of our readers can have seen it. No copy exists at present in the libraries of the Royal Society, the Linnean, or even the Geological Society of London[26]!' He also points out that Hutton's work, and even the more lucid _Illustrations of the Huttonian Theory_, were almost unknown on the continent, owing to the isolation of Great Britain during the war; and he even suggests that the popularity of Playfair in this country may have not improbably led to the neglect of the original work of Hutton[27]. On the continent, indeed, the authority of Cuvier was supreme, and in his _Essay on the Theory of the Earth_, prefixed to his _Opus magnum_--the _Ossemens Fossiles_--the great naturalist threw the whole weight of his influence into the scale of Catastrophism. He maintained that a series of tremendous cataclysms had affected the globe--the last being the Noachian deluge--and that the floods of water that overspread the earth, during each of these events, had buried the various groups of animals, now extinct, that had been successively created. If anything had been wanted in England to support and confirm the views that were then supposed to be the only ones in harmony with the Scriptures, it was found in the great authority of Cuvier. As Zittel justly says, Cuvier's theory of 'World-Catastrophies'--'which afforded a certain scientific basis for the Mosaic account of the "Flood," was received with special cordiality in England, for there, more than in any other country, theological doctrines had always affected geological conceptions[28].' Britain, which had produced the great philosopher, Hutton, had now become the centre of the bitterest opposition to his teachings! But 'the darkest hour of night is that which precedes the dawn,' and while the forces of reaction in this country appeared to be triumphant over Hutton's teaching, there was in preparation, to use the words of Darwin, a 'grand work' ... 'which the future historian will recognise as having produced a revolution in natural science.' CHAPTER V THE REVOLT OF SCROPE AND LYELL AGAINST CATASTROPHISM The year 1797, in which the illustrious Hutton died, leaving behind him the noble fragments of a monumental work, was signalised by the birth of two men, who were destined to bring about the overthrow of Catastrophism, and to establish, upon the firm foundation of reasoned observation, the despised doctrine of Uniformitarianism or Evolution--as outlined by Generelli, Desmarest and Hutton. These two men were George Poulett Thomson (who afterwards took the name of Scrope) and Charles Lyell. Both of them were, from their youth upwards, brought under the strongest influences of the prevalent anti-evolutionary teachings; but both emancipated themselves from the effects of these teachings, being led gradually by their geological travels and observations, not only to reject their early faith, but to become the champions of Evolution. There was a singular parallel between the early careers of these two men. Both were the sons of parents of ample means, and were thus freed from the distractions of a business or profession, while throughout life they alike remained exempt from family cares. Each of them received the ordinary education of the English upper classes--Scrope at Harrow, and Lyell at Salisbury, in a school conducted by a Winchester master on public-school lines. In due course, the two young men proceeded to the University--Scrope to Cambridge, to come under the influence of the sagacious and eloquent Sedgwick, and Lyell to Oxford, to catch inspiration from the enthusiastic but eccentric Buckland. On the opening up of the continent, by the termination of the French wars, each of the young men accompanied his family in a carriage-tour (as was the fashion of the time) through France, Switzerland and Italy; and both utilised the opportunities thus afforded them, to make long walking excursions for geological study. They both returned again and again to the continent for the purpose of geological research, and in the year 1825, at the age of 28, found themselves associated as joint-secretaries of the Geological Society. By this time they had arrived at similar convictions concerning the causes of geological phenomena--convictions which were in direct opposition to the views of their early teachers, and equally obnoxious to all the leaders of geological thought in the infant society which they had joined. [Illustration: G Poulett Scrope] It is interesting to note that each of these two young geologists arrived independently, _as the result of their own studies and observations_, at their conclusions concerning the futility of the prevailing catastrophic doctrines. This I am able to affirm, not only from their published and unpublished letters, but from frequent conversations I had with them in their later years. Scrope, who was slightly the elder of the two friends, spent a considerable time in that wonderful district of France--the Auvergne--in the year 1821, and though he had not seen the map and later memoirs of Desmarest, he pourtrayed the structure of the country in a series of very striking panoramic views, and was led, independently of the great French observer, to the same conclusions as his concerning the volcanic origin of the basalts and the formation of the valleys by river-action. Scrope was at that time equally ignorant of the views propounded both by Generelli and by Hutton. By April 6th, 1822, Scrope had completed his masterly work _The Geology and Extinct Volcanoes of Central France_, and had despatched it to England. It would be idle to speculate now as to what might have been the effect of that work--so full of the results of accurate observation, and so suggestive in its reasoning--had it been published at that time. It is quite possible that much of the credit now justly assigned to Lyell, would have belonged to his friend. Unfortunately, however, Scrope, instead of seeing his work through the press, determined first to make another tour in Italy. He arrived at Naples just in time to witness and describe the grandest eruption of Vesuvius in modern times, that of October 1822. What he witnessed then--the blowing away of the whole upper part of the mountain and the formation of a vast crater 1000 feet deep--made a profound impression on Scrope's mind. His interest thus strongly aroused concerning igneous phenomena, Scrope continued his travels and observations on the volcanic rocks of the peninsula of Italy and its islands, and was thus led to a number of important conclusions in theoretical geology, which he embodied in a work, published in 1825, entitled _Considerations on Volcanos: the probable causes of their phenomena, the laws which determine their march, the disposition of their products, and their connexion with the present state and past history of the globe; leading to the establishment of a New Theory of the Earth_. It is only right to point out that, in calling this book a _new_ 'Theory of the Earth,' Scrope had no intention of comparing it with Hutton's great work, with which he was at that time altogether unacquainted. Nevertheless, his conclusions, though independently arrived at, were almost identical with those of the great Scotch philosopher. But Scrope made the same mistake as Hutton had done before him. He allowed his theoretical conclusions to precede, instead of following upon an account of the observations on which they were based. Scrope's book is certainly one of the most original and suggestive contributions ever made to geological science; but the very speculative character of a large portion of the work led to the neglect of the really valuable hypotheses and acute observations which it contained. In the preface, however, the author gives a most striking and complete summary of the doctrine of Evolution as opposed to Catastrophism, in the inorganic world, as will be shown by the following extracts:-- Geology has for its business a knowledge of the processes which are in continual or occasional operation within the limits of our planet, and the application of these laws to explain the appearances discovered by our Geognostical researches, so as from these materials to deduce conclusions as to the past history of the globe. The surface of the globe exposes to the eye of the Geognost abundant evidence of a variety of changes which appear to have succeeded one another during an incalculable lapse of time. These changes are chiefly, I. Variations of level between different constituent parts of the solid surface of the globe. II. The destruction of former rocks, and their reproduction under another form. III. The production of rocks _de novo_ upon the earth's surface. Geologists have usually had recourse for the explanation of these changes to the supposition of sundry violent and extraordinary catastrophes, cataclysms, or general revolutions having occurred in the physical state of the earth's surface. As the idea imparted by the term Cataclysm, Catastrophe, or Revolution, is extremely vague, and may comprehend any thing you choose to imagine, it answers for the time very well as an explanation; that is, it stops further inquiry. But it has also the disadvantage of effectually stopping the advance of science, by involving it in obscurity and confusion. If, however, in lieu of forming guesses as to what may have been the possible causes and nature of these changes, we pursue that, which I conceive the only legitimate path of geological inquiry, and begin by examining the laws of nature which are actually in force, we cannot but perceive that numerous physical phenomena are going on at this moment on the surface of the globe, by which various changes are produced in its constitution and external characters; changes extremely analogous to those of earlier date, whose nature is the main object of geological inquiry. These processes are principally, I. The Atmospheric phenomena. II. The laws of the circulation and residence of Water on the exterior of the globe. III. The action of Volcanos and Earthquakes. The changes effected before our eyes, by the operation of these causes, in the constitution of the crust of the earth are chiefly-- I. The Destruction of Rocks. II. The Reproduction of others. III. Changes of Level. IV. The Production of New Rocks from the interior of the globe upon its surface. Changes which in their general characters bear so strong an analogy to those which are suspected to have occurred in the earlier ages of the world's history, that, until the processes which give rise to them have been maturely studied under every shape, and then applied with strict impartiality to explain the appearances in question; and until, after a long investigation, and with the most liberal allowances for all possible variations, and an unlimited series of ages, they have been found wholly inadequate to the purpose, it would be the height of absurdity to have recourse to any gratuitous and unexampled hypothesis for the solution of these analogous facts[29]. It was not till 1826, four years after the completion of the work, that Scrope managed to publish his book on the Auvergne, and to tear himself away from the speculative questions by which he had become obsessed. No one could be more candid than he was in acknowledging the causes of his failure to impress his views upon his contemporaries. Writing in 1858, he said of his _Considerations on Volcanos_:-- 'In that work unfortunately were included some speculations on theoretic cosmogony, which the public mind was not at that time prepared to entertain. Nor was this my first attempt at authorship, sufficiently well composed, arranged or even printed, to secure a fair appreciation for the really sound and, I believe, original views on many points of geological interest which it contained. I ought, no doubt, to have begun with a description of the striking facts which I was prepared to produce from the volcanic regions of Central France and Italy, in order to pave the way for a favourable reception, or even a fair hearing, of the theoretical views I had been led from these observations to form[30].' He adds that 'this obvious error was pointed out in a very friendly manner' in a notice of the memoir on _The Geology of Central France_, which was contributed by Lyell to the _Quarterly Review_ in 1827[31]. Scrope's geological career however--though one of so much promise--was brought to a somewhat abrupt termination. In 1821 he had married the last representative and heiress of the Scropes, the old Earls of Wiltshire, and soon afterwards he settled down at the family seat of Castle Combe, eventually devoting his attention almost exclusively to social and political questions. From 1833 to 1868, when he retired from Parliament, he was member for Stroud; and though he seldom took part in the debates, he became famous as a writer of political tracts, thus acquiring the sobriquet of 'Pamphlet Scrope.' He himself used to relate an amusing incident at his own expense. His great friend Lord Palmerston, on being greeted with the question, 'Have you read my last pamphlet?' replied mischievously, 'Well Scrope, I hope I have!' It is sad to relate that, owing to a carriage accident, Scrope's wife became a confirmed invalid and he had no child to succeed to the estate. Though cut off by other duties from the geological world, Scrope maintained his correspondence with his old friend Lyell, and, as we shall see in the sequel, was able to render him splendid service by the luminous though discriminating reviews of the _Principles of Geology_ in the _Quarterly Review_. Throughout his life, however, Scrope preserved a love of geology, and occasionally contributed to the literature of the science; and in his closing years, when unable to travel himself, he gave to others the means of carrying on the researches in which he had from the first been so deeply interested. * * * * * Fortunately for science, Lyell's devotion to geological study was not, like Scrope's, interrupted by the claims made upon him by social and political questions. Feeling though he did, with his friend, the deepest sympathy in all liberal movements, and being especially interested in the reform of educational methods, his geological work always had the first claim on his time and attention, and nothing was allowed to interfere with his scientific labours. [Illustration: Cha Lyell] Charles Lyell was the eldest son of a Scottish laird, whose forbears, after making a fortune in India, had purchased the estate of Kinnordy in Strathmore, on the borders of the Highlands. Lyell's father was a man of culture, a good classical scholar, a translator and commentator on Dante, and a cryptogamic botanist of some reputation. Lyell's mother, an Englishwoman from Yorkshire, was a person of great force of character; this she showed when, on coming to Kinnordy, she found drunkenness so prevalent among the lairds of this part of Scotland, as to cause a fear on her part, that her husband might be drawn into the dangerous society: she therefore induced him, when their son Charles was only three months old, to abandon their Scottish home, and settle in the New Forest of Hampshire. Thus it came about that the future geologist, though born in Scotland, became, by education, habits and association, English. Charles Lyell's attention was first drawn to geology by seeing the quartz-crystals and chalcedony exposed in the broken chalk-flints, which he, as a boy of ten, used to roll down, in company with his school-fellows, from the walls of Old Sarum. Like Charles Darwin, too, he became an ardent and enthusiastic collector of insects, and grew to be a tall and active young fellow, a keen sportsman, with only one drawback--a weakness of the eyes which troubled him through all his after life. It was when at the age of seventeen he went to Oxford and came under the influence of Dr Buckland that Lyell first became deeply engrossed in geology. Lyell used to tell many amusing stories of the oddities of his old teacher and friend Buckland. In his lectures, both in the University and on public platforms, Buckland would keep his audience in roars of laughter, as he imitated what he thought to be the movements of the iguanodon or megatherium, or, seizing the ends of his long clerical coat-tails, would leap about to show how the pterodactyle flew. Lyell became greatly attached to Buckland, who used to take him privately on geological expeditions. On one of these occasions, they were dining at an inn, where a gentleman at another table became greatly scandalised by Buckland's conversation and manners. The professor, seeing this, became more outrageous than ever, and on parting with Lyell for the night took the candle and placed it between his teeth, so as to illuminate the mouth-cavity exclaiming, 'There Lyell, practise this long enough and you will be able to do it as well as I do.' When Buckland had retired, the stranger revealed himself to Lyell as an old friend of his father's, adding 'I hope you will never be seen in the company of that buffoon again.' 'Oh! Sir,' said the startled undergraduate, 'that is my professor at Oxford!' But Buckland did not always originate the fun, for Lyell told me that, when the professor visited Kinnordy in his company, he led him a long tramp under promise of showing him 'diluvium intersected by whin dykes,' and, in the end, pointed to fields in a boulder-clay country separated by gorse ('whin') hedges ('dykes'). Buckland, as shown by his _Vindiciae Geologicae_ (1820) and his _Bridgewater Treatise_ (1836), was the most uncompromising of the advocates for making all geological teaching subordinate to the literal interpretation of the early chapters of Genesis; and in his _Reliquiae Diluvianae_ (1823) he stoutly maintained the view that all the superficial deposits of the globe were the result of the Noachian deluge! He was indeed the great leader of the Catastrophists, and it is not surprising to find Lyell, while still under his influence, scoffing at 'the Huttonians[32].' That Buckland greatly influenced Lyell in his youth, especially by inoculating him with his splendid enthusiasm for geology, there can be no doubt; and Lyell, far as he departed in after life from the views of his teacher, never forgot his indebtedness to the Oxford professor. Even in 1832, in publishing the second edition of the first volume of his _Principles_, he dedicated it to Buckland, as one 'who first instructed me in the elements of geology, and by whose energy and talents the cultivation of science in the country has been so eminently promoted[33].' On leaving Oxford in 1819, at the age of twenty-two, Lyell joined the Geological Society. What were the dominant opinions at that time on geological theory among the distinguished men, who were there laying the foundations of stratigraphical geology, we have already seen. Lyell, in his frequent visits to the continent, became a friend of the illustrious Cuvier, whose strong bias for Catastrophism was so forcibly shown in his writings and conversation. What then, we may ask, were the causes which led Lyell to abandon the views in which he had been instructed, and to become the great champion of Evolutionism? It has often been assumed that Lyell was led by the study of Hutton's works to adopt the Uniformitarian' doctrines. But there is ample evidence that such was not the case. As late as the year 1839, Lyell wrote of Hutton, 'Though I tried, I doubt whether I fairly read half his writings, and skimmed the rest[34]'; and he emphatically assured Scrope 'Von Hoff has assisted me most[35].' The fact is certain that Lyell, quite independently, arrived at the same conclusions as Hutton, _but by totally different lines of reasoning_. As early as 1817, when Lyell was only twenty years of age, he visited the Norfolk coast and was greatly impressed by the evidence of the waste of the cliffs about Cromer, Aldborough, and Dunwich; and three years later we find him studying the opposite kind of action of the sea in the formation of new land at Dungeness and Romney Marsh. All through his life there may be seen the results of these early studies in a tendency which he showed to _overrate marine action_; the chief defect in his early views consisting in not fully realising the importance of that subaerial denudation--of which Hutton was so great an exponent. But it was in his native county of Forfarshire that Lyell found the most complete antidote to the Catastrophic teachings. Buckland had taught him that the 'till' of the country had been thrown down, just 4170 years before, by the Noachian deluge: while Cuvier had asserted that the study of freshwater limestones proved them to differ from any recent deposit by their crystalline character, the absence of shells and the presence of plant-remains, as well as by the occasional occurrence in them of bands of flint. As the result of this, Cuvier and Brongniart had declared that _the freshwater of the ancient world possessed properties which are not observed in that of modern lakes_[36]. Lyell visited Kinnordy from time to time between 1817 and 1824, and found on his father's estate and other localities in Strathmore a number of small lakes, lying in hollows of the boulder clay. These were being drained and their deposits quarried for the purpose of 'marling' the land; the excavations thus made showed that, under peat containing a boat hollowed out of the trunk of a tree, there were calcareous deposits, sometimes 16 to 20 feet in thickness, which passed into a rock, solid and crystalline in character as the materials of the older geological formations and containing the stems and fruits of the freshwater plant _Chara_ (Stone wort). With the help of Robert Brown the botanist, and of analyses made by Daubeny, with the advice of his life-long friend, Faraday, Lyell was able to demonstrate that from the waters of the Forfarshire lakes, containing the most minute proportions of calcareous salts, a limestone, identical in all respects with those of the older rocks of the globe, had been deposited, with excessive slowness, by the action of plant-life[37]. He was thus enabled to supply a complete refutation of the views put forward by Buckland and Cuvier. Thus while Hutton had been led to his conclusion concerning evolution in the inorganic world, by studying the waste going on in the weathered crags and the flooded rivers of his native land, Lyell's conversion to the same views was mainly brought about by the study of changes due to the action of the sea along the English coasts, and by studying the evidence of constant, though slow, deposition of limestone-rocks, by the seemingly most insignificant of agencies. Lyell however did not by any means neglect the study of the action of rain and rivers. During his visits to Forfarshire, he had his initials and the date cut by a mason on many portions of the rocky river-beds about his home. Fifty years afterwards (in 1874) I visited with him the several localities, to ascertain what amount of waste had resulted from the constant flow of water over these hard rocks. It was in most cases singularly small, the inscriptions being still visible, though deprived of their sharpness; even the sandy detritus carried along by the streams, being buoyed up by the water, had not been able in half a century to wear away a thickness of half-an-inch of the hard rock. The most singular result we noticed was, that the leaden small shot fired by sportsmen, in the Highland tracts, whence these streams flowed, had collected in great numbers in hollows formed by the young geologist's inscriptions. By his father's request, Lyell after leaving Oxford studied for the bar, but there is no doubt that his main interest was in geological study. He had made the acquaintance of Dr Mantell, and carried on a number of researches in the south of England either alone or with that geologist[38]. Four years after joining the Geological Society, in which he was a constant worker, he became one of the secretaries. This was in 1823 when he was only 26 years of age. His frequent visits to Paris and to various parts of the continent enabled him to exchange ideas with many foreign naturalists, and it is clear from his correspondence that at this early period he had abandoned the Catastrophic doctrines of his teachers and friends. Let us now consider the outside influences which were at work on Lyell's mind in these early days. In the year 1818, the eminent palaeontologist Blumenbach induced the University of Göttingen to offer a prize for an essay on '_The investigation of the changes that have taken place in the earth's surface conformation since historic times, and the applications which can be made of such knowledge in investigating earth revolutions beyond the domain of history._' A young German, Von Hoff, won the prize by a most able book, displaying great erudition, entitled _The History of those Natural Changes in the Earth's Surface, which are proved by Tradition_. The first volume of this work appeared in 1822, and treated of the results produced on the land by the action of the sea; the second volume, published in 1824, dealt with the effects of volcanoes and earthquakes. Von Hoff's learned work was confined to the collection of data from classical and other early authors bearing on these subjects, and to reasonings based on these records; for, unfortunately, he did not possess the means necessary for travelling and making observations in the districts described by him. Lyell acknowledges the great assistance afforded to him by these two volumes of Von Hoff's work, but, unlike that author, he was able to visit the various localities referred to, and to draw his own conclusions as to the nature of the changes which must have taken place. It is pleasant to be able to relate that the debt which he owed to Von Hoff was fully repaid by Lyell; for the learned German's third volume appeared after the issue of the _Principles of Geology_, and as Zittel assures us 'its influence on Von Hoff is quite apparent in the third volume of his work[39].' At this period, too, Lyell had the advantage of travelling both on the continent and in various parts of Great Britain with the eminent French geologist, Constant Prevost, who had shown his courage by opposing some of the catastrophic teachings of the illustrious Cuvier himself. Still more important to Lyell were the opportunities he enjoyed for comparing his conclusions with those of Scrope, who had joined the Geological Society in 1824, and became a joint secretary with Lyell in the following year. From both of them, in their old age, I heard many statements concerning the closeness and warmth of their friendship, and the constant interchange of ideas which took place between them at this time. From Scrope, Lyell heard of the occurrence of great beds of freshwater limestone in the Auvergne, on a far grander scale than in Strathmore, with many other facts concerning the geology of Central France, which so greatly excited him as in the end to alter all his plans concerning the publication of his own book. As soon as Scrope's great work on Auvergne was published, Lyell undertook the preparation of a review for the _Quarterly_--and this review was a very able and discriminating production. Although Lyell did not derive his views concerning terrestrial evolution directly from Hutton, as is sometimes supposed, there were two respects in which he greatly profited when he came to read Hutton's work at a later date. In the first place, he was very deeply impressed by the necessity of avoiding the _odium theologicum_, which had been so strongly, if unintentionally, aroused by Hutton, of whom he wrote, 'I think he ran unnecessarily counter to the feelings and prejudices of the age. This is not courage or manliness in the cause of Truth, nor does it promote progress. It is an unfeeling disregard for the weakness of human nature, for it is our nature (for what reason heaven knows), but as _it is_ constitutional in our minds, to feel a morbid sensibility on matters of religious faith, I conceive that the same right feeling which guards us from outraging too violently the sentiments of our neighbours in the ordinary concerns of the world and its customs, should direct us still more so in this[40].' In the second place, Lyell was warned by the fate of Hutton's writings that it was hopeless to look for success in combatting the prevailing geological theories, unless he cultivated a literary style very different from that of the _Theory of the Earth_. Lyell's father had to a great extent guided his son's classical studies, and at Oxford, where Lyell took a good degree in classics, he practised diligently both prose and poetic composition. Lyell once told me that his tutor Dalby (afterwards a Dean) had put Gibbon's _Decline and Fall of the Roman Empire_ into his hand with certain passages marked as 'not to be read.' When he had studied the whole work (of course including the marked passages) he said he conceived a profound admiration for the author's literary skill--and this feeling he retained throughout his after life. It is not improbable, indeed, that Lyell learned from Gibbon that a 'frontal attack' on a fortress of error is much less likely to succeed than one of 'sap and mine.' Lyell was always most careful in the composition of his works, sparing no pains to make his meaning clear, while he aimed at elegance of expression and logical sequence in the presentation of his ideas. The weakness of his eyes was a great difficulty to him, throughout his life, and, when not employing an amanuensis, he generally wrote stretched out on the floor or on a sofa, with his eyes close to the paper. The relation of Lyell's views to those of Hutton, may best be described in the words of his contemporary, Whewell, whose remarks written immediately after the publication of the first volume of the _Principles_, lose nothing in effectiveness from the evident, if gentle, note of sarcasm running through them:-- 'Hutton for the purpose of getting his continents above water, or manufacturing a chain of Alps or Andes, did not disdain to call in something more than common volcanic eruptions which we read of in newspapers from time to time. He was content to have a period of paroxysmal action--an extraordinary convulsion in the bowels of the earth--an epoch of general destruction and violence, to usher in one of restoration and life. Mr Lyell throws away all such crutches, he walks alone in the path of his speculations; he requires no paroxysms, no extraordinary periods; he is content to take burning mountains as he finds them; and, with the assistance of the stock of volcanoes and earthquakes now on hand, he undertakes to transform the earth from any one of its geological conditions to any other. He requires time, no doubt; he must not be hurried in his proceedings. But, if we will allow him a free stage in the wide circuit of eternity, he will ask no other favour; he will fight his undaunted way through formations, transition and flötz--through oceanic and lacustrine deposits; and does not despair of carrying us triumphantly from the dark and venerable schist of Skiddaw, to the alternating tertiaries of the Isle of Wight, or even to the more recent shell-beds of the Sicilian coasts, whose antiquity is but, as it were, of yester-myriad of years[41].' Never, surely, did words written in a tone of banter constitute such real and effective praise! But though it is certain that Lyell did not _derive_ his evolutionary views from Hutton, yet when he came to write his historical introduction to the _Principles_, he was greatly impressed by the proofs of genius shown by the great Scotch philosopher, and equally by the brilliant exposition of those views by Playfair in his _Illustrations_. To the former he gave unstinted praise for the breadth and originality of his views, and to the latter for the eloquence of his writings--adopting quotations chosen from these last, indeed, as mottoes for his own work. It is only just to add that for the violent prejudices excited by some of his contemporaries against Hutton's writings--as being directed against the theological tenets of the day and therefore subversive of religion--there is really no foundation whatever; and every candid reader of the _Theory of the Earth_ must acquit its author of any such design. The passage quoted on page 51 could only have been written by Lyell at a time when he was still unacquainted with Hutton's works, and was misled by common report concerning them. It is interesting to note, however, that the passage occurs in a letter written in December 1827, that is after the first draft of the _Principles of Geology_ had been 'delivered to the publisher,' and before the preparation of the historical introduction, which would appear to have led to the first perusal of Hutton's great work, and that of his brilliant illustrator, Playfair. CHAPTER VI 'THE PRINCIPLES OF GEOLOGY' We have seen that as early as the year 1817, when he visited East Anglia, Lyell began to experience vague doubts concerning the soundness of the 'Catastrophist' doctrines, which had been so strongly impressed upon him by Buckland. And these doubts in the mind of the undergraduate of twenty years of age gradually acquired strength and definiteness during his frequent geological excursions, at home and abroad, during the next ten years. At what particular date the design was formed of writing a book and attacking the predominant beliefs of his fellow-geologists, we have no means of ascertaining exactly; but from a letter written to his friend Dr Mantell, we find that at one time Lyell contemplated publishing a book in the form of 'Conversations in Geology[42],' without putting his name to it. This was probably suggested by the manner in which Copernicus and Galileo sought to circumvent theological opposition in the case of Astronomical Theory. But this plan appears to have been soon abandoned; and by the end of the year 1827, when he had reached the age of thirty, Lyell had sent to the printer the first manuscript of the _Principles of Geology_, proposing that it should appear in the course of the following year in two octavo volumes[43]. A great and sudden interruption to this plan occurred however, for just at this time Lyell was engaged in writing his review for the _Quarterly_ of Scrope's work on _The Geology of Central France_, and while doing this his interest was so strongly aroused by the accounts of the phenomena exhibited in the Auvergne, that he was led for a time to abandon the task of seeing his own book through the press; and, having induced Murchison and his wife to accompany him, set off on a visit to that wonderful district. He also felt that, before completing the second part of his book, he needed more information concerning the Tertiary formations, especially in Italy. Lyell had been very early convinced of the supreme importance of travel to the geologist. In a letter to his friend Murchison he said:--'We must preach up travelling, as Demosthenes did "delivery" as the first, second and third requisites for a modern geologist, in the present adolescent state of the science[44].' And Professor Bonney has estimated that so far did he himself practise what he preached, that no less than one fourth of the period of his active life was spent in travel[45]. The joint excursion of Lyell and Murchison to the Auvergne was destined to have great influence on the minds of these pioneers in geological research; both became satisfied from their studies that, with respect to the excavation of the valleys of the country, Scrope's conclusions were irresistible; and in a joint memoir this position was stoutly maintained by them. It is interesting to notice the impression made by these two great geologists on one another during this joint expedition. Murchison wrote that he had seen in Lyell 'the most scrupulous and minute fidelity of observation combined with close application in the closet and ceaseless exertion in the field[46].' But I recollect that Lyell once told me how difficult Murchison found it to restrain himself from impatience, when his companion's attention was drawn aside by his entomological ardour. In an early letter, indeed, we find that Murchison often expressed a wish that Lyell's sisters had been with them to attend to the insect-collecting and thus leave Lyell free for geological work[47]. On the other hand, Lyell informed me that Murchison had rendered him a great service in showing how much a geologist could accomplish by taking advantage of riding on horseback, and he declared in his letters that he 'never had a better man to work with than Murchison'; nevertheless he ridiculed his 'keep-moving-go-it-if-it-kills-you' system as--quoting from the elder Matthews--he called it[48]. On parting from Murchison and his wife, after the Auvergne tour, Lyell proceeded to Italy and for more than a year he was busy studying the Tertiary deposits of Lombardy, the Roman states, Naples and Sicily, and conferring with the Italian geologists and conchologists. Thus it came about that he was not free to resume the task of seeing the _Principles_ through the press till February 1829. Immediately after his return to England Lyell was compelled, with the assistance of his companion Murchison, to defend their conclusions concerning the excavations of valleys by rivers from a determined attack of Conybeare, who was backed up by Buckland and Greenough; the old geologists endeavoured to prove that the river Thames had never had any part in the work of forming its valley[49]. It is interesting to find that, on this occasion, Sedgwick, who was in the chair, was so far influenced by the arguments brought forward by the young men, as to lend some aid to those who had come to be called the 'Fluvialists,' in contradistinction to the 'Diluvialists'; he went so far as to suggest that, with regard to the floods which the Catastrophist invoked, it would be wiser at present to 'doubt and not dogmatise[50].' To what extent the MS. of the _Principles_, sent to the publisher in 1827, was added to and altered two years later, we have no means of knowing; but that the work was to a great extent rewritten would appear from a letter sent to Murchison by Lyell, just before his return to England. In it, he says:-- 'My work is in part written, and all planned. It will not pretend to give even an abstract of all that is known in geology, but it will endeavour to establish _the principle of reasoning_ in the science; and all my geology will come in as illustration of my views of those principles, and as evidence strengthening the system necessarily arising out of the admission of such principles, which, as you know, are neither more nor less than that _no causes whatever_ have from the earliest time to which we can look back to the present, ever acted, but those that are _now acting_, and that they never acted with different degrees of energy from that which they now exert'; but in 1833, in dedicating his third volume to Murchison, he refers to the MS., completed in 1827, as a 'first sketch only of my _Principles of Geology_[51].' At one period, Lyell contemplated again delaying publication till he had visited Iceland. In the end, however, after declining to act as professor of geology in the new 'University of London' (University College), he set himself down steadily to the task of seeing the book through the press. It was at this time that Lyell experienced a singular piece of good fortune, comparable with that which befel Darwin thirty years afterwards, by his book falling into the hands of a very sympathetic reviewer. John Murray, who had undertaken the publication of the _Principles_, was also the publisher of the _Quarterly Review_, and Lockhart, the editor of that publication, undertook that an early notice of the book should appear, if the proof-sheets were sent to the reviewer. Buckland and Sedgwick were successively approached on the subject of reviewing Lyell's book, but both declined on the ground of 'want of time'; though I strongly suspect that their real motive in refusing the task was a disinclination to attack--as they would doubtless have felt themselves compelled to do--a valued personal friend. Conybeare was, fortunately, thought to be out of the question, as Lockhart said he 'promises and does not perform in the reviewing line.' Very fortunately at this juncture, Lockhart, who was in the habit of attending the Geological Society and listening to the debates (for as he used to say to his friends whom he took with him from the Athenaeum, 'though I don't care for geology, yet I _do_ like to see the fellows fight') thought of Scrope. Although he had practically retired from the active work of the Geological Society at this time, Scrope was known as an effective writer, and, happily for the progress of science, he undertook the review of Lyell's book. Although, of course, Lyell had no voice in the choice of a reviewer for the _Principles_, yet he could not fail to rejoice in the fact that it had fallen to his friend, who so strongly sympathised with his views, to introduce it to the public. While the book was being printed and the review of it was in preparation, a number of letters passed between Lyell and Scrope, and the latter, before his death, gave me the carefully treasured epistles of his friend, with the drafts of some of his replies. These letters, some of which have been published, throw much light on the difficulties with which Lyell had to contend, and the manner in which he strove to meet them. As we have already seen, many of the leaders in the Geological Society at that day besides being strongly inclined to Wernerian and Cataclysmal views, had an honest, however mistaken, dread lest geological research should lead to results, apparently not in harmony with the accounts given in Genesis of the Creation and the Flood. Lyell, as this correspondence shows, was most anxious to avoid exciting either scientific or theological prejudice. He wrote, 'I conceived the idea five or six years ago' (that is in 1824 or 5) that 'if ever the Mosaic geology could be set down without giving offence, it would be in an historical sketch[52],' and 'I was afraid to point the moral ... about Moses. Perhaps I should have been tenderer about the Koran[53].' He further says 'full _half_ of my history and comments was cut out, and even many facts, because either I, or Stokes, or Broderip, felt that it was anticipating twenty or thirty years of the march of honest feeling to declare it undisguisedly[54].' Under these circumstances the publication by Scrope of his two long notices of the _Principles_ in the _Review_ which was regarded as the champion of orthodoxy, was most opportune. A very clear sketch was given in these reviews of the leading facts and the general line of argument; and at the same time the allowing of prejudice or prepossession to influence the judgment on such questions was very gently deprecated[55]. But Scrope's reviews did not by any means consist of an indiscriminate advocacy of Lyell's views. In one respect--that of the great importance of subaerial action as contrasted with marine action--Scrope's views were at this time in advance of those of Lyell, and he called especial attention to the direct effects produced by rain in the earth-pillars of Botzen. These Lyell had not at the time seen, but took an early opportunity of visiting. Scrope, too, was naturally much more speculative in his modes of thought than Lyell, and argued for the probably greater intensity in past times of the agencies causing geological change, and for the legitimacy of discussing the mode of origin of the earth. Lyell, like Hutton, argued that he saw '_no signs_ of a beginning,' but his characteristic candour is shown when he wrote:-- 'All I ask is, that at any given period of the past, don't stop enquiry, when puzzled, by a reference to a "beginning," which is all one with "another state of nature," as it appears to me. But there is no harm in your attacking me, provided you point out that it is the _proof_ I deny, not the _probability_ of a beginning[56].' Lyell clearly foresaw the opposition with which his book would be met and wisely resolved not to be drawn into controversy. He wrote:-- 'I daresay I shall not keep my resolution, but I will try to do it firmly, that when my book is attacked ... I will not go to the expense of time in pamphleteering. I shall work steadily on Vol. II, and afterwards, if the work succeeds, at edition 2, and I have sworn to myself that I will not go to the expense of giving time to combat in controversy. It is interminable work[57].' In order to maintain this resolve, Lyell, the moment the last sheet of the volume was corrected, set off for a four months' tour in France and Spain. While absent from England, he heard little of what was going on in the scientific world; but, on his return, Lyell was told by Murray that in the three months before the _Quarterly Review_ article appeared, 650 copies of the volume, out of the 1500 printed, had been sold, and he anticipated the disposal of many more, when the review came out. This expectation was realised and led to the issue of a second edition of the first volume, of larger size and in better type. Lyell, from the first, had seen that it would be impossible to avoid the conclusion that the principles which he was advancing with respect to the inorganic world must be equally applicable to the organic world. At first he only designed to touch lightly on this subject, in the concluding chapters of his first volume, and to devote the second volume to the application of his principles to the interpretation of the geological record. He, however, found it impossible to include the chapters on changes in the organic world in the first volume and then decided to make them the opening portion of the second volume. It is evident, however, that as the work progressed, the interest of the various questions bearing on the origin of species grew in his mind. While Lyell found it impossible to accept the explanation of origin suggested by Lamarck, he was greatly influenced by the arguments in favour of evolution advanced by that naturalist; and as he wrote chapter after chapter on the questions of the modification and variability of species, on hybridity, on the modes of distribution of plants and animals, and their consequent geographical relations, and discussed the struggle of existence going on everywhere in the organic world, in its bearings on the question of 'centres of creation,' he found the second volume growing altogether beyond reasonable limits. His intense interest in this part of his work is shown by his remark, 'If I have succeeded so well with inanimate matter, surely I shall make a lively thing when I have chiefly to talk of living beings[58]?' By December 1831, Lyell had come to the resolution to publish the chapters of his work which dealt with the changes going on in the organic world as a volume by itself. This second volume of the _Principles_ he gracefully dedicated to his friend Broderip, who had rendered him such valuable assistance in all questions connected with Natural History. This volume appeared in January 1832, at the same time that a second edition of the first volume was also issued. The reception of the second volume by the public appears to have been not less favourable than that of the first. In March 1831, Lyell had accepted the Professorship of Geology in King's College, London. In addition to his desire to aid in the work of scientific education, in which he had always taken so great an interest, Lyell seems to have felt that the task of presenting his views in a popular form would be aided by his having to expound them to a miscellaneous audience. For two years, these lectures were delivered, and attracted much attention; the favourable impressions produced by them on a man of the world have been recorded by Abraham Hayward, and on more scientific thinkers by Harriet Martineau. The third volume of the _Principles_ was not completed till a second edition of the second volume had been issued. This third volume, appearing in May 1833, dealt with the classification of the Tertiary strata, to which Lyell had devoted so much labour, studying conchology under Deshayes, and visiting all the chief Tertiary deposits of Europe for the collection of materials. The application of the principles enunciated in the two earlier volumes to the unravelling of the past history of the globe, constituted the chief task undertaken in this part of the great work. But not a few controversial questions were dealt with, and the famous 'metamorphic theory' was advanced in opposition to the Wernerian hypothesis of 'primitive formations.' The volume was appropriately dedicated to Murchison, who had been Lyell's companion in the famous Auvergne excursion, which had produced such an effect on his mind. Within a twelvemonth, a third edition of the whole work in four small volumes was issued, and in the end no less than twelve editions of the _Principles of Geology_ were issued, in addition to portions separately published under the titles of _Manual_, _Elements_, and _Student's Elements of Geology_, of all of which a number of editions have appeared. Lyell was always the most painstaking and conscientious of authors. He declared 'I must write what will be read[59],' and he spared no labour in securing accuracy of statement combined with elegance of diction. His father, a good classical and Italian scholar, had done much towards assisting him to attain literary excellence, and at Oxford, where he took a good degree in classics, he was greatly impressed by the style of Gibbon's writings, and practised both prose and poetic compositions with great diligence. Both Darwin and Huxley always maintained that the real charm and power of Lyell's work are only to be found in the _first edition_[60]. As new discoveries were made or more effective illustrations of his views presented themselves to his mind, passage after passage in the work was modified by the author or replaced by others; and the effects of these constant changes--however necessary and desirable in themselves--could not fail to be detrimental to the book as a work of art. He who would form a just idea of the greatness of Lyell's masterpiece, must read the first edition, of course bearing in mind, all the while, the state of science at the time it was written. CHAPTER VII THE INFLUENCE OF LYELL'S WORKS Although the _Principles of Geology_ was received by the public with something like enthusiasm--due to the cogency of its reasoning and the charm of its literary style--there were not wanting critics who attacked the author on the ground of his heterodox views. It had come to be so generally understood, that every expression of geological opinion should, by way of apology, be accompanied by an attempt to 'harmonise' it with the early chapters of Genesis, that the absence of any references of this kind was asserted to be a proof of 'infidelity' on the part of the author. But Lyell's sincere and earnest efforts to avoid exciting theological prejudice, and the striking illustrations, which he gave in his historical introduction, of the absurdities that had resulted from these prejudices in the past, were not without effect. This was shown in a somewhat remarkable manner in 1831, when, in response to an invitation given to him, he consented to become a candidate for the Chair of Geology at King's College, London, then recently founded. The election was in the hands of an Archbishop, two Bishops and two Doctors of Divinity, and Lyell relates their decision, as communicated to him, in the following words:-- 'They considered some of my doctrines startling enough, but could not find that they were come by otherwise than in a straightforward manner, and (as _I_ appeared to think) logically deducible from the facts, so that whether the facts were true or not, or my conclusions logical or otherwise, there was no reason to infer that I had made my theory from any hostile feeling towards revelation[61].' The appointment was, in the end, made with only one dissentient, and it is pleasing to find that Conybeare, the most determined opponent of Lyell's evolutionary views, was extremely active in his efforts in his support. The result was equally honourable to all parties, and affords a pleasing proof of the fact that in the half century which had elapsed since the persecution of Priestley and Hutton, theological rancour must have greatly declined. But while the reception of the _Principles of Geology_ by the general public was of such a generally satisfactory character, Lyell had to acknowledge that his reasoning had but little effect in modifying the views of his distinguished contemporaries in the Geological Society. The admiration felt for the author's industry and skill, in the collection and marshalling of facts and of the observations made by him in his repeated travels, were eloquently expressed by the generous Sedgwick, as follows:-- 'Were I to tell "the author" of the instruction I received from every chapter of his work, and of the delight with which I rose from the perusal of the whole, I might seem to flatter rather than to speak the language of sober criticism; but I should only give utterance to my honest sentiments. His work has already taken, and will long maintain a distinguished place in the philosophic literature of this country[62].' Nevertheless, in the same address to the Geological Society, in which these words were spoken, Sedgwick goes on to argue forcibly against the doctrine of continuity, and to assert his firm belief in the occurrence of frequent interruptions of the geological record by great convulsions. Whewell was equally enthusiastic with Sedgwick, concerning the value of the body of facts collected by Lyell, declaring that he had established a new branch of science, 'Geological Dynamics'; but he also believed with Sedgwick, that the evolutionary doctrine was as obnoxious to true science as he thought it was to Scripture. These were the views of all the great leaders of geological science at that day, and in 1834, after the completion of the _Principles_, when a great discussion took place in the Geological Society on the subject of the effects ascribed by him to existing causes, Lyell says that 'Buckland, De la Beche, Sedgwick, Whewell, and some others treated them with as much ridicule as was consistent with politeness in my presence[63].' It is interesting to be able to infer from Lyell's accounts of these days, that the sagacious De la Beche was beginning to weaken in his opposition to evolutionary views, and that Fitton and John Phillips were inclined to support him, but neither of them was ready to come forward boldly as the champions of unpopular opinions. John Herschel, who sympathised with Lyell in all his opinions, was absent at the Cape, Scrope was absorbed in the stormy politics of that day, and it was not till Darwin returned from his South American voyage in 1838, that Lyell found any staunch supporter in the frequent lively debates at the Geological Society. It is pleasing, however, to relate that this strong opposition to his theoretical teachings, did not lessen the esteem, or interfere with the friendship, felt for Lyell by his contemporaries. During all this time he held the office of Foreign Secretary to the Society, and in 1835 was elected President, retaining the office for two years. The general feeling of the old geologists with respect to Lyell's opinions was very exactly expressed by Professor Henslow, when in parting from young Darwin on his setting out on his voyage, he referred to the recently published first volume of the _Principles_ in the following terms:-- 'Take Lyell's new book with you and read it by all means, for it is very interesting, but do not pay any attention to it, except in regard to facts, for it is altogether wild as far as theory goes.' (I quote the words as repeated to me by Darwin, in a conversation I had with him on August 7th, 1880, of which I made a note at the time. Darwin has himself referred to this conversation with Henslow in his autobiography[64].) Except in a few cases, this was the attitude maintained by all the old geologists who were Lyell's contemporaries. Even as late as 1895 we find the amiable Prestwich protesting strongly against 'the _Fetish_ of uniformity[65],' and I well remember about the same time being solemnly warned by a geologist of the old school against 'poor old Lyell's fads.' It was not, indeed, till a new generation of geologists had arisen, including Godwin-Austen, Edward Forbes, Ramsay, Jukes, Darwin, Hooker and Huxley, that the real value and importance of Lyell's teaching came to be recognised and acknowledged. The most important influence of Lyell's great work is seen, however, in the undoubted fact that it inspired the men, who became the leaders in the revolution of thought which took place a quarter of a century later in respect to the organic world. Were I to assert that if the _Principles of Geology_ had not been written, we should never have had the _Origin of Species_, I think I should not be going too far: at all events, I can safely assert, from several conversations I had with Darwin, that he would have most unhesitatingly agreed in that opinion. Darwin's devotion to his 'dear master' as he used to call Lyell, was of the most touching character, and it was prominently manifested in all his geological conversations. In his books and in his letters he never failed to express his deep indebtedness to his 'own true love' as he called the _Principles of Geology_. In what was Darwin's own most favourite work, the _Narrative of the Voyage of the Beagle_, he wrote 'To Charles Lyell, Esq., F.R.S., this second edition is dedicated with grateful pleasure, as an acknowledgment that the chief part of whatever scientific merit this Journal and the other works of the author may possess, has been derived from studying the well-known, admirable _Principles of Geology_.' How Lyell's first volume inspired Darwin with his passion for geological research, and how his second volume was one of the determining causes in turning his mind in the direction of Evolution, we shall see in the sequel. In 1844, Darwin wrote to Leonard Horner how 'forcibly impressed I am with the infinite superiority of the Lyellian School of Geology over the continental,' he even says, 'I always feel as if my books came half out of Lyell's brain'; adding 'I have always thought that the great merit of the _Principles_ was that it altered the whole tone of one's mind, and therefore that, when seeing a thing never seen by Lyell one yet saw it partially through his eyes[66].' About the same time Darwin wrote, 'I am much pleased to hear of the call for a new edition of the _Principles_: what glorious good that work has done[67]!' And in the _Origin of Species_ he gives his deliberate verdict on the book, referring to it as 'Lyell's grand work on the _Principles of Geology_, which the future historian will recognise as having produced a revolution in Natural Science[68].' Darwin seemed always afraid, such was his sensitive and generous nature, that he did not sufficiently acknowledge his indebtedness to Lyell. He wrote to his friend in 1845: 'I have long wished not so much for your sake as for my own feelings of honesty, to acknowledge more plainly than by mere reference, how much I geologically owe you. Those authors, however, who like you educate people's minds as well as teach them special facts, can never, I should think, have full justice done them except by posterity, for the mind thus insensibly improved can hardly perceive its own upward ascent.' Very heartily, as I can bear witness from long intercourse with him, was this deep affection of Darwin reciprocated by the man who was addressed by him in his letters as 'Your affectionate pupil.' But a stranger who conversed with Lyell would have thought that he was the junior and a disciple; so profound was his reverence for the genius of Darwin. There can be no doubt that Lyell's extreme caution in statement, and his candour in admitting and replying to objections, had much to do with his acquirement of that authority with general, no less than with scientific, readers, which he so long enjoyed. In his candour he resembled his friend Darwin; but his caution was carried so far that, even after full conviction had entered his mind on a subject, he would still hesitate to avow that conviction. He was always obsessed by a feeling that there still _might be_ objections, which he had not foreseen and met, and therefore felt it unsafe to declare himself. No doubt the peculiarly trying circumstances under which his work was written--a seemingly hopeless protest against ideas held unswervingly by teachers and fellow-workers--led to the creation in him of this habit of mind. Darwin, with all his candour, was of a far more sanguine and optimistic temperament than Lyell, and the difference between them, in this respect, often comes out in their correspondence. Thus Darwin, from the horrors he had witnessed in South America, had come to entertain a most fanatical hatred of slavery--his abhorrence of which he used to express in most unmeasured terms. Lyell, in his travels in the Southern United States, was equally convinced of the undesirability of the institution; but he thought it just to state the grounds on which it was defended, by those who had been his hosts in the Slave-states. Even this, however, was too much for Darwin, and he felt that he must 'explode' to his friend 'How could you relate so placidly that atrocious sentiment' (it was of course only quoted by Lyell) 'about separating children from their parents; and in the next page speak of being distressed at the whites not having prospered: I assure you the contrast made me exclaim out. But I have broken my intention (that is not to write about the matter), so no more of this odious deadly subject[69].' It was just the same in their mode of viewing scientific questions. Thus in 1838, while they were in the midst of the fierce battle with the 'Old Guard' at the Geological Society, Lyell wrote to his brother-in-arms as follows:-- 'I really find, when bringing up my Preliminary Essays in _Principles_ to the science of the present day, so far as I know it, that the great outline, and even most of the details, stand so uninjured, and in many cases they are so much strengthened by new discoveries, especially by yours, that we may begin to hope that the great principles there insisted on will stand the test of new discoveries[70].' To which the younger and more ardent Darwin warmly replied:-- '_Begin to hope_: why, the _possibility_ of a doubt has never crossed my mind for many a day. This may be very unphilosophical, but my geological salvation is staked on it ... it makes me quite indignant that you should talk of _hoping_[71].' When talking with Lyell at this time about the opposition of the old school of geologists to their joint views, Darwin said, 'What a good thing it would be if every scientific man was to die at sixty years old, as afterwards he would be sure to oppose all new doctrines[72].' In conversations that I had with him late in life, Darwin several times remarked to me, that 'he had seen so many of his friends make fools of themselves by putting forward new theoretical views in their old age, that he had resolved quite early in life, never to publish any speculative opinions after he was sixty.' But both in conversation and in his writings he always maintained that Lyell was an exception to all such rules, seeing that at last he adopted the theory of Natural Selection in his old age, thus displaying the most 'remarkable candour.' All who had the pleasure of discussing geological questions with Lyell will recognise the truth of the portrait drawn of his old friend by Darwin, about a year before his own death. He says:-- 'His mind was characterised, as it appeared to me, by clearness, caution, sound judgment, and a good deal of originality. When I made a remark to him on Geology, he never rested until he saw the whole case clearly, and often made me see it more clearly than I had done before.' And he sums up his admiration of the 'dear old master' in the words 'The science of Geology is enormously indebted to Lyell--more so, as I believe, than to any other man who ever lived[73].' Alfred Russel Wallace is scarcely less emphatic than Charles Darwin himself in his expression of affection and admiration for Lyell, and his indebtedness to the _Principles of Geology_. In his Autobiography, Wallace writes:-- 'With Sir Charles I soon felt at home, owing to his refined and gentle manners, his fund of quiet humour, and his intense love and extensive knowledge of natural science. His great liberality of thought and wide general interests were also attractive to me; and although when he had once arrived at a definite conclusion, he held by it very tenaciously until a considerable body of well-ascertained facts could be adduced against it, yet he was always willing to listen to the arguments of his opponents, and to give them careful and repeated consideration[74].' Of the influence of the _Principles of Geology_ in leading him to evolution, he wrote: 'Along with Malthus I had read, and been even more deeply impressed by, Sir Charles Lyell's immortal _Principles of Geology_; which had taught me that the inorganic world--the whole surface of the earth, its seas and lands, its mountains and valleys, its rivers and lakes, and every detail of its climatic conditions--were and always had been in a continual state of slow modification. Hence it became obvious that the forms of life must have become continually adjusted to these changed conditions in order to survive. The succession of fossil remains throughout the whole geological series of rocks is the record of the change; and it became easy to see that the extreme slowness of these changes was such as to allow ample opportunity for the continuous automatic adjustment of the organic to the inorganic world, as well as of each organism to every other organism in the same area, by the simple processes of "variation and survival of the fittest." Thus was the fundamental idea of the "origin of species" logically formulated from the consideration of a series of well ascertained facts[75].' Nor were the two men (who, like Aaron and Hur so steadily sustained the hands of Darwin in his long vigil), behind the two authors of Natural Selection themselves in their devotion to Lyell. How touching is Hooker's tribute of affection on the death of his friend, 'My loved, my best friend, for well nigh forty years of my life. To me the blank is fearful, for it never will, never can be filled up. The most generous sharer of my own and my family's hopes, joys, and sorrows, whose affection for me was truly that of a father and brother combined[76].' And Huxley speaking of Lyell, the day after his death said, 'Sir Charles Lyell would be known in history as the greatest geologist of his time. Some days ago I went to my venerable friend, and put before him the results of the _Challenger_ expedition. Nothing could then have been more touching than the conflict between the mind and the material body, the brain clear and comprehending all; while the lips could hardly express the views which the busy mind formed[77].' How well do I recollect my last visit to Lyell a day or two after this farewell interview with Huxley, the glow of gratitude which lighted up the noble features as with trembling lips he told me how 'Huxley had repeated his whole Royal Institution lecture at his bedside.' Huxley was a most devoted student of Lyell. Speaking to his fellow geologists in 1869 he said, 'Which of us has not thumbed every page of the _Principles of Geology_[78]?' and writing in 1887 on the reception of the _Origin of Species_, he said:-- 'I have recently read afresh the first edition of the _Principles of Geology_; and when I consider that this remarkable book had been nearly thirty years in everybody's hands, and that it brings home to any reader of ordinary intelligence a great principle and a great fact--the principle, that the past must be explained by the present, unless good cause be shown to the contrary; and the fact, that, so far as our knowledge of the past history of life on our globe goes, no such cause can be shown--I cannot but believe that Lyell, for others, as for myself, was the chief agent in smoothing the road for Darwin. For consistent uniformitarianism postulates evolution as much in the organic as in the inorganic world. The origin of a new species by other than ordinary agencies would be a vastly greater 'catastrophe' than any of those which Lyell successfully eliminated from sober geological speculation[79].' How strongly Lyell had become convinced, as early as 1832, of the truth and importance of the doctrine of Evolution--in the _organic_ as well as in the inorganic world--in spite of his emphatic rejection of the theory of Lamarck, we shall show in the next chapter. It was this conviction, as we shall see, which led to his friendly encouragement of Darwin in his persevering investigations and to his constant solicitude that the results of his friend's labours should not be lost through delay in their publication. CHAPTER VIII EARLY ATTEMPTS TO ESTABLISH THE DOCTRINE OF EVOLUTION FOR THE ORGANIC WORLD In studying the history of Evolutionary ideas, it is necessary to keep in mind that there are two perfectly distinct lines of thought, the origin and development of which have to be considered. _First._ The conviction that species are not immutable, but that, by some means or other, new forms of life are derived from pre-existing ones. _Secondly._ The conception of some process or processes, by which this change of old forms into new ones may be explained. Buffon, Kant, Goethe, and many other philosophic thinkers, have been more or less firmly persuaded of the truth of the first of these propositions; and even Linnaeus himself was ready to make admissions in this direction. It was impossible for anyone who was convinced of the truth of the doctrine of continuity or evolution in the _inorganic_ world, to avoid the speculation that the same arguments by which the truth of that doctrine was maintained must apply also to the _organic_ world. Hence we find that directly the _Principles of Geology_ was published, thinkers, like Sedgwick and Whewell, at once taxed Lyell with holding that 'the creation of new species is going on at the present day,' and Lyell replied to the latter:-- 'It was impossible, I think, for anyone to read my work and not to perceive that my notion of uniformity in the existing causes of change always implied that they must for ever produce an endless variety of effects, _both in the animate and inanimate world_[80].' And to Sedgwick, Lyell wrote:-- 'Now touching my opinion,' concerning the creation of new species at the present day, 'I have no right to object, _as I really entertain it_, to your controverting it; at the same time you will see, on reading my chapter on the subject, that I have studiously avoided laying down the doctrine dogmatically as capable of proof. I have admitted that we have only data for _extinction_, and I have left it to be inferred, instead of enunciating it even as my opinion, that the place of lost species is filled up (as it was of old) from time to time by new species. I have only ventured to say that had new mammalia come in, we could hardly have hoped to verify the fact[81].' That Lyell was convinced of the truth of the doctrine of the evolution of species is shown by his correspondence with friends and sympathisers like Scrope and John Herschel. But he wrote: 'If I had stated ... the possibility of the introduction or origination of fresh species being a natural, in contradistinction to a miraculous process, I should have raised a host of prejudices against me, which are unfortunately opposed at every step to any philosopher who attempts to address the public on these mysterious subjects[82].' That Lyell was justified in not increasing the difficulties which would retard the reception of his views, by introducing matter, which he still regarded as of a more or less speculative character, I think everyone will be prepared to admit. Darwin had to contend with the same difficulty in writing the _Origin of Species_. To have included the question of the origin of mankind _prominently_ in that work would have raised an almost insurmountable barrier to its reception. He says in his autobiography, 'I thought it best, in order that no honourable man should accuse me of concealing my views, to add that by the work "light would be thrown on the origin of man and his history." It would have been useless and injurious to the success of the book to have paraded, without giving evidence, my conviction with respect to his origin[83].' Huxley and Haeckel have both borne testimony to the fact that Lyell, at the time he wrote the _Principles_, was firmly convinced that new species had originated by evolution from old ones. Indeed in a letter to John Herschel in 1836 he goes very far in the direction of anticipating the lines in which enquiries on the _method_ of evolution must proceed, having even a prevision of the doctrine of _mimicry_, long afterwards established by Bates and others. Lyell wrote:-- 'In regard to the origination of new species, I am very glad to find that you think it probable that it may be carried on through the intervention of intermediate causes. I left this rather to be inferred, not thinking it worth while to offend a certain class of persons by embodying in words what would only be a speculation.... One can in imagination summon before us a small part at least of the circumstances that must be contemplated and foreknown, before it can be decided what powers and qualities a new species must have in order to enable it to endure for a given time, and to play its part in due relation to all other beings destined to coexist with it, before it dies out.... It may be seen that unless some slight additional precaution be taken, the species about to be born would at a certain era be reduced to too low a number. There may be a thousand modes of ensuring its duration beyond that time; one, for example, may be the rendering it more prolific, but this would perhaps make it press too hard upon other species at other times. Now if it be an insect it may be made in one of its transformations to resemble a dead stick, or a leaf, or a lichen, or a stone, so as to be somewhat less easily found by its enemies; or if this would make it too strong, an occasional variety of the species may have this advantage conferred on it; or if this would be still too much, one sex of a certain variety. Probably there is scarcely a dash of colour on the wing or body of which the choice would be quite arbitrary, or which might not affect its duration for thousands of years. I have been told that the leaf-like expansions of the abdomen and thighs of a certain Brazilian Mantis turn from green to yellow as autumn advances, together with the leaves of plants among which it seeks its prey. Now if species come in succession, such contrivances must sometimes be made, and such relations predetermined between species, as the Mantis, for example, and plants not then existing, but which it was foreseen would exist together with some particular climate at a given time. But I cannot do justice to this train of speculation in a letter, and will only say that it seems to me to offer a more beautiful subject for reasoning and reflecting on, than the notion of great batches of new species all coming in and afterwards going out at once[84].' We have cited this very remarkable passage, as it affords striking evidence of how deeply Lyell had thought on this great question at a very early period. Nevertheless it is certain that when he wrote the second volume of the _Principles_, he had not been able to satisfy himself that any hypothesis of the _mode_ of evolution, that had up to that time been suggested, could be regarded as satisfactory. The only serious attempt to _explain_ the derivation of new species from old ones that came before Lyell was that of the illustrious Lamarck. Very noteworthy was the work of that old wounded French soldier, afflicted in his later years as he was by blindness. By his early labours, Lamarck had attained a considerable reputation as a botanist, and later in life he turned his attention to zoology, and then to palaeontology and geology. In zoology, he did for the study of invertebrate animals what his great contemporary Cuvier was accomplishing for the vertebrates; but, with regard to the origin of species, he arrived at conclusions directly at variance with those of his distinguished rival. We are indebted to Professor Osborn[85] for calling attention to that remarkable, but little known work of Lamarck's--_Hydrogéologie_--published in 1802, seven years before his _Philosophie Zoologique_ appeared. This work is especially interesting as showing to how great an extent--as in the case of Darwin, Wallace and others--it was geological phenomena which played an important part in leading Lamarck to evolutionary convictions. "In Geology," Professor Osborn writes, 'Lamarck was an ardent advocate of uniformity, as against the Cataclysmal School. The main principles are laid down in his _Hydrogéologie_, that all the revolutions of the earth are extremely slow. "For Nature," he says, "time is nothing. It is never a difficulty, she always has it at her disposal; and it is for her the means by which she has accomplished the greatest as well as the least results[86]."' On the subject of subaerial denudation (the action of rain and rivers in wearing down the earth's surface), Lamarck's views were as clear and definite as those of Hutton himself; though it is almost certain that he could never have seen, or even heard of, the writings of the great Scottish philosopher. On some other questions of geological dynamics, however, it must be confessed that Lamarck's views and speculations were rather crude and unsatisfactory. In his _Philosophie Zoologique_, published in the same year that Charles Darwin was born (1809), Lamarck brought forward a great body of evidence in favour of evolution, derived from his extensive knowledge of botany, zoology and geology. He showed how complete was the gradation between many forms ranked as species, and how difficult it was to say what forms should be classed as 'varieties' and what as 'species.' But when he came to indicate a possible method by which one species might be derived from another, he was less happy in his suggestions. He recognised the value of the evidence derived from the study of the races which have arisen among domestic animals, and from the crossing of different forms. But his main argument was derived from the acknowledged fact that use or disuse may cause the development or the partial atrophy of organs--the case of the 'blacksmith's arm.' Unfortunately some of the suggestions made by Lamarck, in this connexion--like that of the elongation of the giraffe's neck to enable it to browse on high trees--were of a kind that made them very susceptible to ridicule. His theory was of course dependent on the admission that acquired characters were transmitted from parents to children, and in the absence of any suggestion of 'selection,' it did not appeal strongly to thinkers on this question. Lyell first became acquainted with the writings of Lamarck in 1827. As he was returning from the Oxford circuit for the last time--having now resolved to give up law and devote himself to geological work exclusively--he wrote to his friend Mantell as follows:-- 'I devoured Lamarck _en voyage_.... His theories delighted me more than any novel I ever read, and much in the same way, for they address themselves to the imagination, at least of geologists who know the mighty inferences which would be deducible were they established by observations. But though I admire even his flights, and feel none of the _odium theologicum_ which some modern writers in this country have visited him with, I confess I read him rather as I hear an advocate on the wrong side, to know what can be made of the case in good hands. I am glad he has been courageous enough and logical enough to admit that his argument, if pushed as far as it must go, if worth anything, would prove that men may have come from the Ourang-Outang. But after all, what changes species may really undergo! How impossible will it be to distinguish and lay down a line, beyond which some of the so-called extinct species have never passed into recent ones. That the earth is quite as old as he supposes, has long been my creed, and I will try before six months are over to convert the readers of the _Quarterly_ to that heterodox opinion[87].' Lyell was at that time at work on his review for the _Quarterly_ of Scrope's _Central France_, and was also completing the 'first sketch' of the _Principles_. But it is evident that as the result of continued study of Lamarck's book, Lyell found it, in spite of its fascination, to embody a theory which he could not but regard as unsound and not calculated to prove a solution of the great mystery of evolution. Accordingly when the second volume of the _Principles_ was issued in 1832, it was found to contain in its opening chapters a very trenchant criticism of Lamarck's theory. It is only fair to remember, however, that in 1863, after Lyell had accepted the theory of Natural Selection he wrote to Darwin: 'When I came to the conclusion that after all Lamarck was going to be shown to be right, and that we must "go the whole orang" I re-read his book, and remembering when it was written, I felt I had done him injustice[88].' It is interesting also to notice that Darwin, like Lyell, gradually came to entertain a higher opinion of the merit of Lamarck's works, than he did on his first perusal of them. In 1844, Darwin wrote to Hooker, 'Heaven forfend me from Lamarck nonsense!' and in the same year he speaks of Lamarck's book as 'veritable rubbish,' an 'absurd though clever work[89].' When, after the publication of the _Origin of Species_, Lyell referred to the _conclusions_ arrived at in that work as similar to those of Lamarck, Darwin expressed something like indignation, and he wrote to their 'mutual friend' Hooker, 'I have grumbled a bit in my answer to him' (Lyell) 'at his _always_ classing my book as a modification of Lamarck's, which it is no more than any author who did not believe in the immutability of species[90].' In this case, as is so frequently seen in the writings of Darwin, it is evident that he attaches infinitely less importance to the establishment of the _fact_ of the evolution of species, than to the demonstration of a possible _mode of origin_ of that evolution. But that later in life Darwin came to take a more indulgent view of the result of Lamarck's labours is shown by a passage in his 'Historical Sketch' prefixed to the _Origin_, in 1866. Lamarck, he says, 'first did the eminent service of arousing attention to the probability of all change in the organic world, as well as in the inorganic world, being the result of law and not of miraculous interposition[91].' In the opinion of Dr Schwalbe and others there are indications in Darwin's later writings that he had come into much closer relation with the views of Lamarck, than was the case when he wrote the _Origin_[92]. It is interesting, however, to note that Erasmus Darwin, the grandfather of Charles, published independently and contemporaneously, views on the nature and causes of evolution in striking agreement with those of Lamarck; but perhaps the poetical form, in which he chose to embody his ideas, led to their receiving less attention than they deserved. As is now well known a number of writers during the earlier years of the nineteenth century published statements in favour of evolutionary views, and in several cases the theory of natural selection was more or less distinctly outlined. In addition to Geoffroy and Isidore Saint Hilaire and d'Omalius d'Halloy on the continent, a number of writers in this country, such as Dr Wells, Mr Patrick Matthew, Dr Pritchard, Professor Grant, Dean Herbert, all expressed views in favour of evolution, even, in some cases, foreshadowing Natural Selection as the method. But these authors attached so little importance to their suggestions, that they did not even take the trouble to place them on permanent record, and it is certain that neither Lyell nor Darwin was acquainted with their writings at the time they were themselves working at the subject. There was indeed one work which, during the time that the _Origin of Species_ was in preparation, attracted much popular attention. In 1844, Robert Chambers, who was favourably known as the author of some geological papers, wrote a book which excited a great amount of attention--the well-known _Vestiges of Creation_. This work was a very bold pronouncement of evolutionary views. Beginning with a statement of the nebular hypothesis of Kant and Laplace, it discussed the question of the origin of life--when life became possible on a cooling globe--and, arguing strongly in favour of the view that all plants and animals, as the conditions under which they existed change, had given rise to new forms, better adapted to their environment, insisted that the whole living creation had been gradually developed from the simplest types. Chambers published his book anonymously, being naturally afraid of the prejudices that would be excited against him--especially in his own country--by a work so outspoken, and it was not till after his death that its authorship was definitely known. The _Vestiges of Creation_ met with very different receptions at the hands of the general public and from the scientific world, at the time it was published. The former were startled but captivated by its fearless statements and suggestive lines of thought; while the latter were repelled and incensed by the want of judgment, too frequently shown, in accepting as indisputable, facts and experiments which really rested on a very slender basis or none at all. So popular was the book, however, that it passed through twelve editions, the last being published after the appearance of the _Origin of Species_. It is interesting to read Darwin's judgment in later life on this once famous book; he says:-- 'The work from its powerful and brilliant style, though displaying in the earlier editions little accurate knowledge and a great want of scientific caution, immediately had a very wide circulation. In my opinion it has done excellent service in this country in calling attention to the subject, in removing prejudice, and in thus preparing the ground for the reception of analogous views[93].' If we enquire what was the attitude of scientific naturalists towards the doctrine of Evolution, immediately before the occurrence of the events to be recorded in the next chapter, we shall find some diversity of opinion to exist. The late Professor Newton, an eminent ornithologist, has asserted that, at this period, many systematic zoologists and botanists had begun to feel great 'searchings of heart' as to the possibility of maintaining what were the generally prevalent views concerning the reality and immutability of species. Huxley, however, declared that he and many contemporary biologists were ready to say 'to Mosaists and Evolutionists a plague to both your houses!' and were disposed to turn aside from an interminable and fruitless discussion, to labour in the fields of ascertainable fact[94]. CHAPTER IX DARWIN AND WALLACE: THE THEORY OF NATURAL SELECTION Charles Darwin was the grandson of Erasmus Darwin, who, as we have seen, arrived independently at conclusions concerning the origin of species very similar to those of Lamarck, and embodied his views in poems, which, at the time of their publication, achieved a considerable popularity. In the younger philosopher, however, imagination was always kept in subjection by a determination to '_prove_ all things' and 'to hold fast that which is good'; though, in other respects, there were not wanting indications of the existence of hereditary characteristics in the grandson. Born at Shrewsbury and educated in the public school of that town, Charles Darwin from the first exhibited signs of individuality in his ideas and his tastes. The rigid classical teaching of his school did not touch him, but, with the aid of his elder brother, he surreptitiously started a chemical laboratory in a garden tool-house. From his earliest infancy he was a collector, first of trifles, like seals and franks, but later of stones, minerals and beetles. At the outset, only the desire to possess new things animated him, then a wish to put names to them, but, at a very early period, a passion arose for learning all he could about them. Thus when only 9 or 10 years of age, he had 'a desire of being able to know something about every pebble in front of the hall-door,' and at 13 or 14, when he heard the remark of a local naturalist, 'that the world would come to an end before anyone would be able to explain how' a boulder (the 'bell-stone' of local-fame) came to be brought from distant hills--the lad had such a deep impression made on his mind, that he says in after life, 'I _meditated_ over this wonderful stone[95].' At the age of 16, he was sent to Edinburgh University to prepare himself for the work of a doctor--the profession of his father and grandfather. But here his independence of character again asserted itself. He found most of the lectures 'intolerably dull,' so he occupied himself with other pursuits, making many friendships among the younger naturalists and doing a little in the way of biological research himself. That he was not altogether destitute of ambition in the eyes of his companions, however, is, I think, indicated by an amusing circumstance. In the library of Charles Darwin, which is carefully preserved at Cambridge, there is a copy of Jameson's _Manual of Mineralogy_, published in 1821, which was evidently used by the young student in his classwork at Edinburgh. In this a quizzical fellow-student has written 'Charles Darwin Esq., M.D., F.R.S.'--mischievously adding 'A.S.S.'! Even for geology, the science to which in all his after life he became so deeply devoted, young Darwin conceived the most violent aversion; and as he listened to Jameson's Wernerian outpourings at Salisbury Crags, he 'determined never to attend to geology,' registering the terrible vow 'never as long as I lived to read a book on Geology, or in any way to study the science[96].' As it became evident that Charles Darwin would never make a doctor, his father, after two years' trial, sent him to Cambridge with the object of his qualifying for a clergyman. But at Christ's College, in that University, he again took his own line--which was not that of divinity--riding, shooting and beetle-hunting being his chief delights. Nevertheless, at Cambridge as at Edinburgh, he seems to have shown an appreciation for good and instructive society, and in Henslow, the judicious and amiable Professor of Botany, the young fellow found such sympathy and kindly help that he came to be distinguished as 'the man who walks with Henslow[97].' After achieving a 'pass degree,' Darwin went back to the University for an extra term, and by the advice of Henslow began to 'think about' the despised Science of Geology. He was introduced to that inspiring teacher, Sedgwick, with whom he made a geological excursion into Wales; but though he said he 'worked like a tiger' at geology, yet he, when he got the chance of shooting on his uncle's estate, had to make the confession, 'I should have thought myself mad to give up the first days of partridge-shooting for geology or any other science[98].' There is a sentence in one of the letters written at this time which suggests that, even at this early period in his geological career, Darwin had begun to experience some misgivings concerning the catastrophic doctrines of his teachers and contemporaries. He says:-- 'As yet I have only indulged in hypotheses, but they are such powerful ones that I suppose, if they were put into action but for one day, the world would come to an end[99].' Was he not poking fun at other hypotheses besides his own? Darwin's real scientific education began when, after some hesitation on his father's part, he was allowed to accept the invitation, made to him through his friend Henslow, to accompany, at his own expense, the surveying ship _Beagle_ in a cruise to South America and afterwards round the world. In the narrow quarters of the little 'ten-gun brig,' he learned methodical habits and how best to economise space and time; during his long expeditions on shore, rendered possible by the work of a surveying vessel, he had ample opportunities for observing and collecting; and, above all, the absence of the distractions from quiet meditation, afforded by a long sea-voyage, proved in his case invaluable. Very diligently did he work, accumulating a vast mass of notes, with catalogues of the specimens he sent home from time to time to Henslow. He had received no careful biological training, and Huxley considered that the voluminous notes he made on zoological subjects were almost useless[100]. Very different was the case, however, with his geological notes. He had learned to use the blowpipe, and simple microscope, as well as his hammer and clinometer; and the notes which he made concerning his specimens, before packing them up for Cambridge, were at the same time full, accurate and suggestive. Darwin has recorded in his autobiography the wonderful effect produced on his mind by the reading of the first volume of Lyell's _Principles_--an effect very different from that anticipated by Henslow[101]. From that moment he became the most enthusiastic of geologists, and never fails in his letters to insist on his preference for geology over all other branches of science. Again and again we find him recording observations that he thinks will 'interest Mr Lyell' and he says in another letter:-- 'I am become a zealous disciple of Mr Lyell's views, as known in his admirable book. Geologising in South America, I am tempted to carry parts to a greater extent even than he does[102].' Before reaching home after his voyage, the duration of which was fortunately extended from two to five years, he had sent home letters asking to be elected a fellow of the Geological Society; and, immediately on his arrival, he gave up his zoological specimens to others and devoted his main energies for ten years to the working up of his geological notes and specimens. It may seem strange that the grandson of Erasmus Darwin should in early life have felt little or no interest in the question of the 'Origin of Species,' but such was certainly the case. He tells us in his autobiography that he had read his grandfather's _Zoonomia_ in his youth, without its producing any effect on him, and when at Edinburgh he says he heard his friend Robert Grant (afterwards Professor of Zoology in University College, London) as they were walking together 'burst forth in high admiration of Lamarck and his views on Evolution'--yet Darwin adds 'I listened in silent astonishment, and as far as I can judge without any effect on my mind[103].' The reason of this indifference towards his grandfather's works is obvious. All through his life, Darwin, like Lyell, showed a positive distaste for all speculation or theorising that was not based on a good foundation of facts or observations. In this respect, the attitude of Darwin's mind was the very opposite of that of Herbert Spencer--who, Huxley jokingly said, would regard as a 'tragedy'--'the killing of a beautiful theory by an ugly fact.' Darwin tells us himself that, while on his first reading of _Zoonomia_ he 'greatly admired' it--evidently on literary grounds--yet 'on reading it a second time after an interval of ten or fifteen years, I was much disappointed; _the proportion of speculation being so large to the facts given_.' Huxley who knew Charles Darwin so well in later years said of him that:-- 'He abhors mere speculation as nature abhors a vacuum. He is as greedy of cases and precedents as any constitutional lawyer, and all the principles he lays down are capable of being brought to the test of observation and experiment[104].' What then, we may ask, were the facts and observations which turned Darwin's mind towards the great problem that came to be the work of his after life? I think it is possible from the study of his letters and other published writings to give an answer to this very interesting question. In November 1832, Darwin returned to Monte Video, from a long journey in the interior of the South American Continent, bringing with him many zoological specimens and a great quantity of fossil bones, teeth and scales, dug out by him with infinite toil from the red mud of the Pampas--these fossils evidently belonging to the geological period that immediately preceded that of the existing creation. The living animals represented in his collection were all obviously very distinct from those of Europe--consisting of curious sloths, anteaters, and armadilloes--the so-called 'Edentata' of naturalists. And when young Darwin came to examine and compare his _fossil_ bones, teeth and scales he found that they too must have belonged to animals (megatherium, mylodon, glyptodon, etc.) quite distinct from but of strikingly similar structure to those now living in South America. What could be the meaning of this wonderful analogy? If Cuvier and his fellow Catastrophists were correct in their view that, at each 'revolution' taking place on the earth's surface, the whole batch of plants and animals was swept out of existence, and the world was restocked with a 'new creation,' why should the brand-new forms, at any particular locality, have such a 'ghost-like' resemblance to those that had gone before? It is interesting to note that, just at the same time, a similar discovery was made with respect to Australia. In caves in that country, a number of bones were found which, though evidently belonging to 'extinct' animals, yet must have belonged to forms resembling the kangaroos and other 'pouched animals' (marsupials) now so distinctive of that continent. But of this fact Darwin was not aware until after his return to England in 1836. Among the objects sent from home, which awaited Darwin on his return to Monte Video, was the second volume of Lyell's _Principles_, then newly published; this book, while rejecting Lamarckism, was crowded with facts and observations concerning variation, hybridism, the struggle for existence, and many other questions bearing on the great problem of the origin of species. I think there can be no doubt that from this time Darwin came to regard the question of species with an interest he had never felt before. It is of course not suggested that, at this early date, Darwin had formed any definite ideas as to the _mode_ in which new species might possibly arise from pre-existing ones or even that he had been converted to a belief in evolution. Indeed in 1877 he wrote 'When I was on board the _Beagle_ I believed in the permanence of species' yet he adds 'but as far as I can remember _vague doubts_ occasionally flitted across my mind.' Such 'vague doubts' could scarcely have failed to have arisen when, as happened during all his journeys from north to south of the South American Continent, he found the same curious correspondence between existing and late fossil forms of life again and again illustrated. But towards the end of the voyage, an even stronger element of doubt as to the immutability of species was awakened in his mind. When he came to study the forms of life existing in the Galapagos Islands, off the west coast of South America, he was startled by the discovery of the following facts. Each small island had its own 'fauna' or assemblage of animals--this being very strikingly shown in the case of the reptiles and birds. And yet, though the _species_ were different, there was obviously a very wonderful 'family likeness' to one another between the forms in the several islands and between them all and the animals living in the adjoining portion of the continent. Surely this could not be accidental, but must indicate relationships due to descent from common ancestors! Charles Darwin returned to England in 1836, and at once made the acquaintance of Lyell. He says in one place, 'I saw a great deal of Lyell' and in another that 'I saw more of Lyell than of any other man, both before and after my marriage.' In one of his letters he writes, 'You cannot conceive anything more thoroughly good natured than the heart-and-soul manner in which he put himself in my place and thought what would be best to do[105].' For two years Darwin was comparatively free from the distressing malady which clouded so much of his after life. And, during that time, he engaged very heartily with Lyell in those combats at the Geological Society (of which he had become one of the Secretaries) in which their joint views concerning the truth of continuity or evolution in the inorganic world were defended against the attacks of the militant catastrophists. Darwin, however, did not act on the defensive alone, but brought forward a number of papers strongly supporting his new friend's views. There can be little doubt that, while thus engaged, and in constant friendly intercourse with Lyell, Darwin must have felt--like other earnest thinkers on geology at that day--that the principles they were advocating of 'continuity' in the inorganic world must be equally applicable to the organic world--and thus that the question of evolution would acquire a new interest for him. But it was undoubtedly the revision of the notes made on board the _Beagle_, and the study of the specimens which had been sent home by him from time to time, that produced the great determining influence on Darwin's career. All through the voyage he had endeavoured, with as much literary skill as he could command, to record with accuracy the observations he made, and the conclusions to which, on careful reflection, they seemed to point. And on his return to England, these patiently written journals were revised and prepared for publication forming that charming work _A Naturalist's Voyage. Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of H.M.S. 'Beagle' round the world._ As Darwin, with the specimens before him, revised his notes, and reconsidered the impressions made on his mind, the 'vague doubts' he had entertained, from time to time, concerning the immutability of species, would come back to him with new force and cumulative effect. 'I then saw,' he says, 'how many facts indicated the common descent of species,' and further, 'It occurred to me in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it.' In July of that year, he opened his first note-book on the subject[106]--the note-books being soon replaced by a series of portfolios, in which extracts from the various works he read, facts obtained by correspondence, the records of experiments and observation, and ideas suggested by constant meditation were slowly accumulated for twenty years. Mr Francis Darwin has published a series of extracts from the note-book of 1837, which amply prove that by this time Charles Darwin had become 'a convinced evolutionist[107].' Fifteen months after this 'systematic enquiry' began, Darwin happened to read the celebrated work of Malthus _On Population_, for amusement, and this served as a spark falling on a long prepared train of thought. The idea that as animals and plants multiply in geometrical progression, while the supplies of food and space to be occupied remain nearly constant, and that this must lead to a 'struggle for existence' of the most desperate kind, was by no means new to Darwin, for the elder De Candolle, Lyell and others had enlarged upon it; yet the facts with regard to the human race, so strikingly presented by Malthus, brought the whole question with such vividness before him that the idea of 'Natural Selection' flashed upon Darwin's mind. This hypothesis cannot be better or more succinctly stated than in Huxley's words. 'All _species_ have been produced by the development of _varieties_ from common stocks: by the conversion of these, first into _permanent races_ and then into _new species_, by the process of _natural selection_, which process is essentially identical with that artificial selection by which man has originated the races of domestic animals--the _struggle for existence_ taking the place of man, and exerting, in the case of natural selection, that selective action which he performs in artificial selection[108].' With characteristic caution, Darwin determined not to write down 'even the briefest sketch' of this hypothesis, that had so suddenly presented itself to his mind. His habit of thought was always to give the fullest consideration and weight to any possible objection that presented itself to his own mind or could be suggested to him by others. Though he was satisfied as to the truth and importance of the principle of natural selection, there is evidence that for some years he was oppressed by difficulties, which I think would have seemed greater to him than to anyone else. In my conversations with Darwin, in after years, it always struck me that he attached an exaggerated importance to the merest suggestion of a view opposed to that he was himself inclined to adopt; indeed I sometimes almost feared to indicate a _possible_ different point of view to his own, for fear of receiving such an answer as 'What a very striking objection, how stupid of me not to see it before, I must really reconsider the whole subject.' While a divinity student at Cambridge, Darwin had been much struck with the logical form of the works both of Euclid and of Paley. The rooms of the latter he seems to have actually occupied at Christ's College and the works of the great divine were so diligently studied that their deep influence remained with him in after life[109]. I think it must have been the remembrance of the arguments of Paley on the 'proofs of design' in Nature, that seem in after life to have haunted Darwin so that for long he failed to recognise fully that the principle of natural selection accounted not only for the _adaptation_ of an organism to its environment, but at the same time explains that _divergence_, which must have taken place in species in order to give rise to their wonderfully varied characters. It was not till long after he came to Down in 1842, he tells us in his autobiography, that his mind freed itself from this objection. He says:-- 'I can remember the very spot in the road, whilst in my carriage, when to my joy the solution occurred to me,' and he compares the relief to his mind as resembling the effect produced by 'Columbus and his egg[110].' Some may think the 'solution' of Columbus was itself not a very satisfactory one; and I am inclined to regard the difficulties of which Darwin records so sudden and dramatic a removal as more imaginary than real! There can be no doubt that, as pointed out by the late Professor Alfred Newton[111], there was among naturalists during the second quarter of the nineteenth century a feeling of dissatisfaction with respect to current ideas concerning the origin of species, accompanied in many cases with one of expectation that a solution might soon be found. Others, however, despairingly regarded it as 'the mystery of mysteries' for which it was hopeless to attempt to find a key. There was, however, one man, who simultaneously with Darwin was meditating earnestly on the problem and who eventually reached the same goal. Alfred Russel Wallace was born thirteen years after Darwin, and a quarter of a century after Lyell. He did not possess the moderate income that permits of entire devotion to scientific research--an advantage, the importance of which in their own cases, both Lyell and Darwin were always so ready to acknowledge. Wallace, after working for a time as a land-surveyor and then as a teacher, at the age of 26 set off with another naturalist, H. W. Bates, on a collecting tour in South America--hoping by the sale of specimens to cover the expenses of travel. Like Lyell and Darwin, he was an enthusiastic entomologist, and had conceived the same passion for travel. He had, as we have already seen, been deeply impressed by reading the _Principles of Geology_, and after spending four years in South America undertook a second collecting tour, which lasted twice that time, in the Malay Archipelago. [Illustration: Alfred R. Wallace] Before leaving England in 1848, Wallace had read and been impressed by reading the _Vestiges of Creation_, and there can be no doubt that from that period the question of evolution was always more or less distinctly present in his mind. While in Sarawak in the wet season, he tells us, 'I was quite alone with one Malay boy as cook, and during the evenings and wet days I had nothing to do but to look over my books and ponder over the problem which was rarely absent from my thoughts.' He goes on to say that by 'combining the ideas he had derived from his books that treated of the distribution of plants and animals with those he obtained from the great work of Lyell' he thought 'some valuable conclusions might be reached[112].' Thus originated the very remarkable paper, _On the Law which has regulated the Introduction of New Species_, the main conclusion of which was as follows: 'Every species has come into existence coincident both in space and time with a pre-existing closely allied species.' As Wallace has himself said, 'This clearly pointed to some kind of evolution ... but the _how_ was still a secret.' This essay was published in the _Annals and Magazine of Natural History_ in September 1855. It attracted much attention from Lyell and Darwin and later from Huxley. One important result of it was that Darwin and Wallace entered into friendly correspondence. But although Darwin in his letters to Wallace informed him that he had been engaged for a long time in collecting facts which bore on the question of the origin of species, he gave no hint of the theory of natural selection he had conceived seventeen years before--indeed his friends Lyell and Hooker appear at that time to have been the only persons, outside his family circle, whom he had taken into his confidence. In the spring of 1858, Wallace was at Ternate in the island of Celebes, where he lay sick with fever, and as his thoughts wandered to the ever-present problem of species, there suddenly recurred to his memory the writings of Malthus, which he had read twelve years before. Then and there, 'in a sudden flash of insight' the idea of natural selection presented itself to his mind, and after a few hours' thought the chief points were written down, and within a week the matter was 'copied on thin letter-paper' and sent to Darwin by the next post, with a letter to the following effect[113]. Wallace stated that the idea seemed new to himself and he asked Darwin, if he also thought it new, to show it to Lyell, who had taken so much interest in his former paper. Little did Wallace think, in the absence of all knowledge on his part of Darwin's own conclusions, what stir would be made by his paper when it arrived in England! Wallace's essay was entitled _On the Tendency of Varieties to depart indefinitely from the Original Type_, and it is a singularly lucid and striking presentment, in small compass, of the theory of Natural Selection. Had these two men been of less noble and generous nature, the history of science might have been dishonoured by a painful discussion on a question of priority. Fortunately we are not called upon for anything like a judicial investigation of rival claims; for Darwin as soon as he read the essay saw that--as Lyell had often warned him might be the case--he was completely forestalled in the publication of his theory. The letter and paper arrived at a sad time for Darwin--he was at the moment very ill, there was 'scarlet fever raging in his family, to which an infant son had succumbed on the previous day, and a daughter was ill with diphtheria[114].' Darwin at once wrote hurriedly to Lyell enclosing the essay and saying: 'I never saw a more striking coincidence; if Wallace had my MS. sketch written out in 1842, he could not have made a better short abstract! Even his terms now stand as heads of my chapters. Please return me the MS., which he does not say he wishes me to publish, but I shall, of course, at once write and offer to send to any journal. So all my originality, whatever it may amount to, will be smashed, though my book, if it ever have any value, will not be deteriorated, as all the labour consists in the application of the theory. I hope you will approve of Wallace's sketch, that I may tell him what to say[115].' And Wallace--what was the line taken by him in the unfortunate complication that had thus arisen? From the very first his action was all that is generous and noble. Not only did he, from the first, entirely acquiesce in the course taken by Lyell and Hooker, but, writing in 1870, when the fame of Darwin's work had reached its full height, he said:-- 'I have felt all my life and I still feel, the most sincere satisfaction that Mr Darwin had been at work long before me, and that it was not left for me to attempt to write _The Origin of Species_. I have long since measured my own strength and know well that it would be quite unequal to that task. For abler men than myself may confess, that they have not that untiring patience in accumulating, and that wonderful skill in using, large masses of facts of the most varied kind,--that wide and accurate physiological knowledge,--that acuteness in devising and skill in carrying out experiments,--and that admirable style of composition, at once clear, persuasive and judicial,--qualities which in their harmonious combination mark out Mr Darwin as the man, perhaps of all men now living, best fitted for the great work he has undertaken and accomplished[116].' And fifty years after the joint publication of the theory of Natural Selection to the Linnean Society he said: '_I_ was then (as often since) the "young man in a hurry," _he_' (Darwin) 'the painstaking and patient student, seeking ever the full demonstration of the truth he had discovered, rather than to achieve immediate personal fame[117].' And when he referred to the respective shares of Darwin and himself to the credit of having brought forward the theory of natural selection, he actually suggests as a fair proportion '_twenty years to one week_'--those being the periods each had devoted to the subject[118]! Never surely was such a noble example of personal abnegation! We admire the generosity, though we cannot accept the estimate, for do we not know that, for at least half the period of Darwin's patient quest, Wallace had spent in deeply pondering upon the same great question? CHAPTER X THE ORIGIN OF SPECIES In the preceding chapter I have endeavoured to show how the hypothesis of Natural Selection originated in the minds of its authors, and must now invite attention to the way in which it was introduced to the world. What has been said earlier with respect to the labours and writings of Hutton, Scrope and Lyell may serve to indicate the great importance of the _manner_ of presentment of new ideas--the logical force and literary skill with which they are brought to the notice of scientific contemporaries and the world at large. There are some striking passages in Darwin's naive 'autobiography and letters' which indicate the beginnings of his ambition for literary distinction. It must always be borne in mind in reading this autobiography, however, that it was not intended by Darwin for publication, but only for the amusement of the members of his own family. But the charming and unsophisticated self-revelations in it will always be a source of delight to the world. When making his first original observations among the volcanic cones and craters of St Jago in the Cape-de-Verde Islands, he says 'It then first dawned on me that I might perhaps write a book on the geology of the different countries visited, and this made me thrill with delight[119].' He tells us concerning his regular occupations on board the _Beagle_, that 'during some part of the day, I wrote my Journal and took much pains in describing carefully and vividly all that I had seen: and this was good practice[120].' 'Later in the voyage' he says 'FitzRoy' (the Captain of the _Beagle_) 'asked me to read some of my Journal and declared it would be worth publishing, so here was a second book in prospect[121]!' Darwin's first published writings were the extracts from his letters which Henslow read to the Philosophical Society of Cambridge, and those which Sedgwick submitted to the Geological Society. At Ascension, on the voyage home, a letter from Darwin's sisters had informed him of the commendation with which Sedgwick had spoken to his father of these papers, and he wrote fifty years afterwards: 'After reading this letter, I clambered over the mountains of Ascension with a bounding step, and made the volcanic rocks ring under my geological hammer.' When in 1839 his charming _Journal of Researches_ was published he records that 'The success of this my first literary child always tickles my vanity more than that of any of my other books[122].' As a matter of fact, no one could possibly be more diffident and modest about his actual literary performances than was Charles Darwin. I have heard him again and again express a wish that he possessed 'dear old Lyell's literary skill'; and he often spoke with the greatest enthusiasm of the 'clearness and force of Huxley's style.' On one occasion he mentioned to me, with something like sadness in his voice, that it had been asserted 'there was a want of connection and continuity in the written arguments,' and he told me that, while engaged on the _Origin_, he had seldom been able to write, without interruption from pain, for more than twenty minutes at a time! Charles Darwin never spoke definitely to me about the nature of the sufferings that he so patiently endured. On the occasion of my first visit to him at Down he wrote me a letter (dated August 25th, 1880) in which, after giving the most minute and kindly directions concerning the journey, he arranged that his dog-cart should bring me to the house in time for a 1 o'clock lunch, telling me that to catch a certain train for return, it would be necessary to leave his house a little before 4 o'clock. But he added significantly:-- 'But I am bound to tell you that I shall not be able to talk with you or anyone else for this length of time, however much I should like to do so--but you can read newspaper or take a stroll during part of the time.' His constant practice, whenever I visited him, either at Down or at his brother's or daughter's house in London, was to retire with me, after lunch, to a room where we could 'talk geology' for about three quarters of an hour. At the end of that time, Mrs Darwin would come in smilingly, and though no word was spoken by her, Darwin would at once rise and beg me to read the newspaper for a time, or, if I preferred it, to take a stroll in the garden; and after urging me to stay 'if I could possibly spare the time,' would go away, as I understood to lie down. On his return, about half an hour later, the discussion would be resumed where it had been left off, without further remark. Mr Francis Darwin has told us that the nature and extent of his father's sufferings--so patiently and uncomplainingly borne--were never fully known, even to his own children, but only to the faithful wife who devoted her whole life to the care of his health. As is well known, Darwin seldom visited at other houses, besides those of immediate relatives, or the hydropathic establishment at which he sought relief from his illness. But he was in the habit of sometimes, when in London, calling upon David Forbes the mineralogist (a younger brother of Edward Forbes) then living in York Street, Portman Square. The bonds of union between Charles Darwin and David Forbes were, first, that they had both travelled extensively in South America, and secondly, that both were greatly interested in methods of preserving and making available for future reference all notes and memoranda collected from various sources. David Forbes devoted to the purpose a large room with the most elaborate system of pigeon-holes, about which he told me that Darwin was greatly excited. He also mentioned to me that, on one or more occasions, while Darwin was in his house, pains of such a violent character had seized him that he had been compelled to lie down for a time and had occasioned his host the greatest alarm. It must always therefore be remembered, in reading Darwin's works, what were the sad conditions under which they were produced. It seems to be doubtful to what extent his ill-health may be regarded as the result of an almost fatal malady, from which he suffered in South America, or as the effect of the constant and prolonged sea-sickness of which he was the victim during the five years' voyage. But certain it is that his work was carried on under no ordinary difficulties, and that it was only by the exercise of the sternest resolution, in devoting every moment of time that he was free from pain to his tasks, that he was able to accomplish his great undertakings. I do not think, however, that any unprejudiced reader will regard Darwin's literary work as standing in need of anything like an apology. He always aims--and I think succeeds--at conveying his meaning in simple and direct language; and in all his works there is manifest that undercurrent of quiet enthusiasm, which was so strikingly displayed in his conversation. It was delightful to witness the keen enjoyment with which he heard of any new fact or observation bearing on the pursuits in which he was engaged, and his generous nature always led him to attach an exaggerated value to any discovery or suggestion which might be brought to his knowledge--and to appraise the work of others above his own. The most striking proof of the excellence and value of Darwin's literary work is the fact that his numerous books have attained a circulation, in their original form, probably surpassing that of any other scientific writings ever produced--and that, in translations, they have appealed to a wider circle of readers than any previous naturalist has ever addressed! We have seen that the idea of Natural Selection 'flashed on' Darwin's mind in October 1838, and although he was himself inclined to think that his _complete_ satisfaction with it, as a solution of the problem of the origin of species, was delayed to a considerably later date, yet I believe that this was only the result of his over-cautious temperament, and we must accept the date named as being that of the real birth of the hypothesis. At this early date, too, it is evident that Darwin conceived the idea that he might accomplish for the principle of evolution in the organic world, what Lyell had done, in the _Principles_, for the inorganic world. To cite his own words, 'after my return to England it appeared to me that by following the example of Lyell in Geology, and by collecting all facts which bore in any way on the variation of animals and plants under domestication and nature, some light might perhaps be thrown on the whole subject[123].' 'In June 1842,' he says, 'I first _allowed_ myself' (how significant is the phrase!) 'the satisfaction of writing a brief abstract of my theory in pencil in 35 pages[124].' For many years it was thought that this first sketch of Darwin's great work had been lost. But after the death of Mrs Darwin in 1896, when the house at Down was vacated, the interesting MS. was found 'hidden in a cupboard under the stairs which was not used for papers of any value but rather as an overflow of matters he did not wish to destroy[125].' By the pious care of his son, this interesting MS.--hurriedly written and sometimes almost illegible--has been given to the world, and it proves how completely Darwin had, at that early date, thought out the main lines of his future _opus magnum_. Darwin, however, had no idea of publishing his theory to the world until he was able to support it by a great mass of facts and observations. Lyell, again and again, warned him of the danger which he incurred of being forestalled by other workers; while his brother Erasmus constantly said to him, 'You will find that some one will have been before you[126]!' The utmost that Darwin could be persuaded to do, however, was to enlarge his sketch of 1842 into one of 230 pages. This he did in the summer of 1844. His manner of procedure seems to have been that, keeping to the same general arrangement of the matter as he had adopted in his original sketch, he elaborated the arguments and added illustrations. Each of the 35 pages of the pencilled sketch, as it was dealt with, had a vertical line drawn across it and was thrown aside. While the 'pencilled sketch' of 1842 was little better than a collection of memoranda, which, though intelligible to the writer at the time, are sometimes difficult either to decipher or to understand the meaning of, the expanded work of 1844 was a much more connected and readable document, which Darwin caused to be carefully copied out. The work was done in the summer months, while he was absent from home, and unable therefore to refer to his abundant notes--Darwin speaks of it, therefore, as 'done from memory.' The two sketches, as Mr Francis Darwin points out, were each divided into two distinct parts, though this arrangement is not adopted in the _Origin of Species_, as finally published. Charles Darwin on many occasions spoke of having adopted the _Principles of Geology_ as his model. That work as we have seen consisted of a first portion (eventually expanded from one to two volumes), in which the general principles were enunciated and illustrated, and a second portion (forming the third volume), in which those principles were applied to deciphering the history of the globe in the past. I think that Darwin's original intention was to follow a similar plan; the first part of his work dealing with the evidences derived from the study of variation, crossing, the struggle for existence, etc., and the second to the proofs that natural selection had really operated as illustrated by the geological record, by the facts of geographical distribution, and by many curious phenomena exhibited by plants and animals. Although this plan was eventually abandoned--no doubt wisely--when the _Origin_ came to be written, we cannot but recognise in it another illustration of the great influence exercised by Lyell and his works on Darwin--an influence the latter was always so ready to acknowledge. On the 5th July 1844, Darwin wrote a letter to his wife in which he said, 'I have just finished my sketch of my species theory. If, as I believe, my theory in time be accepted, even by one competent judge, it will be a considerable step in science.' He goes on to request his wife, 'in case of my sudden death' to devote £400 (or if found necessary £500) to securing an editor and publishing the work. As editor he says 'Lyell would be the best, if he would undertake it,' and later, 'Lyell, especially with the aid of Hooker (and if any good zoological aid), would be best of all.' He then suggests other names from which a choice might be made, but adds 'the editor must be a geologist as well as naturalist.' Fortunately for the world Mrs Darwin was never called upon to take action in accordance with the terms of this affecting document[127]. It must be remembered that, at this time, Darwin was hard at work on the three volumes of the _Geology of the Beagle_, and on the second and revised edition of his _Journal of Researches_. This which he considered his 'proper work' he stuck to closely, whenever his health permitted. He had hoped to complete these books in three or four years, but they actually occupied him for _ten_, owing to constant interruptions from illness. His occasional neglect of this task, and indulgence in his 'species work,' as he called it, was always spoken of at this time by Darwin as 'idleness.' And when the geological and narrative books were finished, Darwin took up the systematic study of the Barnacles (_Cirripedia_), both recent and fossil, and wrote two monumental works on the subject. These occupied eight years, two out of which he estimated were lost by interruptions from illness. So absorbed was he in this work, that his children regarded it as the _necessary occupation_ of a man,--and when a visitor in the house was seen not to be so employed one of them enquired of their mother, 'When does Mr ---- do _his_ Barnacles?' Huxley has left on record his view that in devoting so long a time to the study of the Barnacles Darwin 'never did a wiser thing,' for it brought him into direct contact with the principles on which naturalists found 'species[128].' And Hooker has expressed the same opinion. Daring these years of labour in geology and zoology--interrupted only by the 'hours of idleness'--devoted to 'the species question,' Darwin, though leading at Down almost the life of a hermit, was nevertheless in frequent communication with two or three faithful friends who followed his labours with the deepest interest. Cautious as was Darwin himself, he found in his life-long friend Lyell, a still more doubting and critical spirit, and it is clear from what Darwin says that he derived much help by laying new ideas and suggestions before him. The year before Darwin's death he wrote of Lyell, 'When I made a remark to him on Geology, he never rested till he saw the whole case clearly, and often made me see it more clearly than I had done before.' Lyell's father was a botanist of considerable repute, the friend of Sir William Hooker and his distinguished son Dr (now Sir Joseph) Hooker. While Darwin was writing his _Journal of Researches_, he handed the proof-sheets to Lyell with permission to show them to his father, who was a man of great literary judgment. The elder Lyell, in turn, showed them to young Mr Hooker, who was then preparing to join Sir James Ross, in his celebrated Antarctic voyage with H.M. ships _Erebus_ and _Terror_. Hooker was then working hard to take his doctor's degree before joining the expedition as surgeon, but he kept Darwin's proof-sheets under his pillow, so as to get opportunities of reading them 'between waking and rising.' Before leaving England, however, Hooker in 1839 casually met and was introduced to Darwin, and thus commenced a friendship which resulted in such inestimable benefits to science. Before sailing with the Antarctic expedition the young surgeon received from Charles Lyell, as a parting gift, 'a copy of Darwin's _Journal_ complete'; and he tells us that the perusal stimulated in him 'an enthusiasm in the desire to travel and observe[129].' On Hooker's return from the voyage in 1843, a friendly letter from Darwin commenced that remarkable correspondence, which will always afford the best means of judging of the development of ideas in Darwin's mind. Hooker's wide knowledge of plants--especially of all questions concerning their distribution--was of invaluable assistance to Darwin, at a time when his attention was more particularly absorbed by geology and zoology, while botany had not as yet received much attention from him. Hooker's experience, gained in travel, his sound judgment and balanced mind made him a judicious adviser, while his caution and candour fitted him to become a trenchant critic of new suggestions, scarcely inferior in that respect to Lyell. Darwin does not appear to have made the acquaintance of Huxley till a considerably later date; but we find the great comparative anatomist had in 1851 already become so deeply impressed by Darwin, that he said in writing to a friend he 'might be anything if he had good health[130].' Huxley used to visit Darwin at Down occasionally, and I have often heard the latter speak of the instruction and pleasure he enjoyed from their intercourse. For many years of his life, Darwin used to come to London and stay with his brother or daughter for about a week at a time, and on these occasions--which usually occurred about twice in the year I believe--he would meet Lyell to 'talk Geology,' Hooker for discussions on Botany, and Huxley for Zoology. For twenty years Darwin had 'collected facts on a wholesale scale, more especially with respect to domesticated productions, by printed enquiries, by conversations with skilful breeders and gardeners, and by extensive reading.' 'When,' he added, 'I see the list of books of all kinds which I read and abstracted, including whole series of Journals and Transactions, I am surprised at my industry[131].' In September 1854 the Barnacle work was finished and 10,000 specimens sent out of the house and distributed, and then he devoted himself to arranging his 'huge pile of notes, to observing and experimenting in relation to the transmutation of species.' It was early in 1856 when this work had been completed, that, again urged by Lyell, he actually commenced writing his book. It was planned as a work on a considerable scale and, if finished, would have reached dimensions three or four times as great as did eventually the _Origin of Species_. Working steadily and continuously he had got as far as Chapter X, completing more than one half the book, when as he says Wallace's letter and essay came 'like a bolt from the blue.' Oppressed by illness, anxiety and perplexity, as we have seen that Darwin was at the time, he fortunately consented to leave matters--though with great reluctance--in the hands of his friends Lyell and Hooker. They took the wise course of reading Wallace's paper at the Linnean Society on July 1st, 1858, at the same time giving extracts from Darwin's memoir written in 1844, and the abstract of a letter written by Darwin in 1857 to the distinguished American botanist, Asa Gray. This solution of the difficulty happily met with the complete approval of Wallace; and, as the result of the episode, Darwin came to the conclusion that it would not be wise to defer full publication of his views, until the extensive work on which he was engaged could be finished, but an 'abstract' of them must be prepared and issued with as little delay as possible. For a time there was hesitation, as Darwin's correspondence with Lyell and Hooker shows, between the two plans of sending this 'abstract' to the Linnean Society in a series of papers or of making it an independent book. But Darwin entertained an invincible dislike to submitting his various conclusions to the judgment of the Council of a Society, and, in the end, the preparation of the 'Abstract' in the form of a book of moderate size, was decided on. This was the origin of Darwin's great work. The sickness at Down had led to the abandonment of the house for a time, and, three weeks after the reading of the joint paper at the Linnean Society, we find Darwin temporarily established at Sandown, in the Isle of Wight, where the writing of the _Origin of Species_ was commenced. The work was resumed in September when the family returned to Down, and from that time was pressed forward with the greatest diligence. For the first half of the book, the task before Darwin was to condense, into less than one half their dimensions, the chapters he had already written for the large work as originally projected. But for the second half of the book, he had to expand directly from the essay of 1844. So closely did Darwin apply himself to the work, that, by the end of March 28th, 1859, he was able to write to Lyell telling him that he hoped to be ready to go to press early in May, and asking advice about publication: he says, 'My Abstract will be about five hundred pages of the size of your first edition of the _Elements of Geology_.' Lyell introduced Darwin to John Murray, who had issued all his own works, and the present representative of that publishing firm has placed on record a very interesting account of the ever thoughtful and considerate relations between Darwin and his publishers, which were maintained to the end[132]. The MS. of the book seems to have been practically finished early in May, and Darwin's health then broke down for a time, so completely that he had to retire to a hydropathic establishment. By June 21st he was able to write to Lyell 'I am working very hard, but get on slowly, for I find that my corrections are terrifically heavy, and the work most difficult to me. I have corrected 130 pages, and the volume will be about 500. I have tried my best to make it clear and striking, but very much fear that I have failed; so many discussions are and must be very perplexing. _I have done my best._ If you had all my materials, I am sure you would have made a splendid book. I long to finish, for I am certainly worn out[133].' On September 10th the last proof was corrected and the preparation of the index commenced. At the meeting of the British Association in Aberdeen, Lyell made the important announcement of the approaching publication of the great work. On November 24th the book was issued, 1250 copies having been printed, and Darwin wrote to Murray, 'I am infinitely pleased and proud at the appearance of my child.' The edition was sold out in a day, and was followed early in the next year by the issue of 3000 copies; and untold thousands have since appeared. The writing of such a work as the _Origin of Species_, in so short a time--especially taking into consideration the condition of its author's health--was a most remarkable feat. It would, of course, not have been possible but for the fact that Darwin's mind was completely saturated with the subject, and that he had command of such an enormous body of methodically arranged notes. He showed the greatest anxiety to convince his scientific contemporaries, and at the same time to make his meaning clear to the general reader. With the former object, both MS. and printed proofs were submitted to the criticism of Lyell and Hooker; and the latter end was obtained by sending the MS. to a lady friend, Miss G. Tollet--she, as Darwin says 'being an excellent judge of style, is going to look out errors for me.' Finally the proofs of the book were carefully read by Mrs Darwin herself. The splendid success achieved by the work is a matter of history. Its clearness of statement and candour in reasoning pleased the general public; critics without any profound knowledge of natural history were beguiled into the opinion that they _understood_ the whole matter! and, according to their varying tastes, indulged in shallow objection or slightly offensive patronage. The fully-anticipated, theological vituperation was of course not lacking, but most of the 'replies' to Darwin's arguments were 'lifted' from the book itself, in which objections to his views were honestly stated and candidly considered by the author. The best testimony to the profound and far-reaching character of the scientific discussions of the _Origin of Species_ is found in the fact that both Hooker and Huxley, in spite of their wide knowledge and long intercourse with Darwin, found the work, so condensed were its reasonings, a 'very hard book' to read, one on which it was difficult to pronounce a judgment till after several perusals! It would be idle to speculate at the present day whether the cause of Evolution would have been better served by the publication, as Darwin at one time proposed, of a 'Preliminary Essay,' like that of 1844, or by the great work, which had been commenced and half completed in 1858, rather than by the 'abstract,' in which the theory of Natural Selection was in the end presented to the world. Probably the more moderate dimensions of the _Origin of Species_ made it far better suited for the general reader; while the condensation which was necessitated did not in the end militate against its influence with men of science. It will I think be now generally conceded that the great success of this grand work was fully deserved. A subject of such complexity as that which it dealt with could only be adequately discussed in a manner that would demand careful attention and thought on the part of the reader; and Darwin's well-weighed words, carefully balanced sentences, and guarded reservations are admirably adapted to the accomplishment of the difficult task he had undertaken. The _Origin of Species_ has been read by the millions with pleasure, and, at the same time, by the deepest thinkers of the age with conviction. It is scarcely possible to refer to the literary style of Darwin's work without a reference to a misconception arising from that very candid analysis of his characteristics which he wrote for the satisfaction of his family, but which has happily been given to the world by his son. In his early life Darwin was exceedingly fond of music, and took such delight in good literature, especially poetry, that when on his journeys in South America he found himself able to carry only one book with him, the work chosen was the poems of Milton--the former student of his own Christ's College, Cambridge. But towards the end of his life, Darwin had sadly to confess that he found that he had quite lost the capacity of enjoying either music or the noblest works of literature. Some have argued that Darwin's scientific labours must have actually proved destructive to his artistic and literary tastes, and have even gone so far as to assert--in spite of numerous examples to the contrary--that there is a natural antithesis between the mental conditions that respectively favour scientific and artistic excellence. But I think there is a very simple explanation of the loss by Darwin of his powers of enjoyment of music and poetry, a loss which he evidently greatly deplored. His scientific undertaking was so gigantic, and, at the same time, his health was so broken and precarious, that he felt his only chance of success lay in utilizing, for the tasks before him, every moment that he was free from acute suffering and retained any power of working. Consequently, when the self-imposed task of each day was completed, he found himself in a state of mental collapse. Now to appreciate the beauties of fine music or the work of a great writer certainly demands that the mind should be fresh and unjaded, whereas, at the only times Darwin had for relaxation, he was quite unfitted for these higher delights. We are not surprised then to learn that he sought and found relief in listening to his wife's reading of some pleasant novel or in the nightly game of backgammon, as the only means of resting his wearied brain. No one who had the privilege of conversing with Darwin in his later years can doubt of his having retained to the end the full possession of his refined tastes as well as his great mental powers. His love for and sympathy with every movement tending to progress--especially in the scientific and educational world--his devotion to his friends, with no little indulgence of indignation for what he thought false or mean in others, these were his conspicuous characteristics, and they were combined with a gentle playfulness and sense of humour, which made him the most delightful and loveable of companions. CHAPTER XI THE INFLUENCE OF DARWIN'S WORKS In two essays 'On the Coming of Age of the Origin of Species[134],' and 'On the Reception of the Origin of Species[135],' published in 1880 and 1887 respectively, Huxley has discussed the course of events following the publication of Darwin's great work, he having the advantage of being one of the chief actors in those events. There is a striking parallelism between the manner that the _Principles of Geology_ had been received thirty years earlier, and the way that the _Origin of Species_ was met, both by Darwin's scientific contemporaries and the reading public. At the outset, as we have already intimated, Lyell and Darwin were equally fortunate, in that each found a critic, in one of the chief organs of public opinion, who was at the same time both competent and sympathetic. The story of the lucky accident by which this came about in Darwin's case has been told by Huxley himself[136]. 'The _Origin_ was sent to Mr Lucas, one of the staff of the _Times_ writers at that time, in what was I suppose the ordinary course of business. Mr Lucas, though an excellent journalist, ... was as innocent of any knowledge of science as a babe, and bewailed himself to an acquaintance on having to deal with such a book. Whereupon, he was recommended to ask me to get him out of the difficulty, and he applied to me accordingly, explaining, however, that it would be necessary for him formally to adopt anything I might be disposed to write, by prefacing it with two or three paragraphs of his own.' 'I was too anxious to seize upon the opportunity thus offered of giving the book a fair chance with the multitudinous readers of the _Times_, to make any difficulty about conditions; and being then very full of the subject, I wrote the article faster, I think, than I ever wrote anything in my life, and sent it to Mr Lucas who duly prefixed his opening sentences[137].' Many journalists, however, were less conscientious than Mr Lucas, and most of the other early notices of the book were pretty equally divided between undiscriminating praise of it as a novelty and foolish reprobations of its 'wickedness.' It was fortunate that Darwin followed the strong advice given to him by Lyell, and did not attempt to reply to the adverse criticisms; for the only effect of these was to arouse curiosity and thus to increase the circulation of the book. Although Darwin had wisely avoided the danger of exciting prejudice against his work by definitely applying the theory of Natural Selection to the case of man--simply remarking, in order to avoid the charge of concealing his views, that 'light would be thrown on the origin of man and his history'--yet friends and foes alike at once drew what was the necessary corollary from the theory. It is as amusing, as it is surprising at the present day, to recall the storm of prejudice which was excited. At the British Association Meeting at Oxford in 1860, after an American professor had indignantly asked the question, 'Are we a fortuitous concourse of atoms?' as a comment on Darwin's views, Dr Samuel Wilberforce, the Bishop of Oxford, ended a clever but flippant attack on the _Origin_ by enquiring of Huxley, who was present as Darwin's champion, if it 'was through his grandfather or his grandmother that he claimed his descent from a monkey?' Huxley made the famous and well-deserved retort:-- 'I asserted--and I repeat--that a man has no reason to be ashamed of having an ape for his grandfather. If there were an ancestor whom I should feel ashamed in recalling, it would rather be a _man_--a man of restless and versatile intellect--who not content with success in his own sphere of activity, plunges into scientific questions with which he has no real acquaintance, only to obscure them by an aimless rhetoric, and distract the attention of his hearers from the real point at issue by eloquent digressions and skilled appeals to religious prejudice[138].' The violent attack on Darwin's views by the once-famous Bishop of Oxford was outdone, a few years later, by an even more absurd outburst on the part of Benjamin Disraeli, who--after stigmatising Darwinism as the question 'Is man an ape or an angel?'--declared magniloquently to the episcopal chairman, 'My Lord, I am on the side of the angels!' But in spite of attacks like these and numerous bitter pasquinades and comic cartoons--perhaps to some extent in consequence of them--Darwin's views became widely known and eagerly discussed, so that the circulation of the _Origin of Species_ went up by leaps and bounds. Nevertheless, as Huxley said, 'years had to pass away before misrepresentation, ridicule and denunciation, ceased to be the most notable constituents of the multitudinous criticisms of his work which poured from the press.' Among his contemporary men of science Darwin could at first count few converts. Hooker, whose candid and valuable criticisms of his friend's work had been continued up to the very end during its composition, did an eminent service to the cause of Evolution by publishing, almost simultaneously with the _Origin of Species_, his splendid memoir on _The Flora of Australia, its Origin, Affinities, and Distribution_, in which similar views were, not obscurely, indicated. Of Lyell, Darwin's other friend and counsellor, Huxley justly says: 'Lyell, up to that time a pillar of the antitransmutationists (who regarded him, ever afterwards, as Pallas Athene may have looked at Dian, after the Endymion affair), declared himself a Darwinian, though not without putting in a serious _caveat_. Nevertheless, he was a tower of strength and his courageous stand for truth as against consistency, did him infinite honour[139].' Huxley himself accepted the theory of Natural Selection--but not without some important reservations--these, however, did not prevent him from becoming its most ardent and successful champion. Darwin used to acknowledge Huxley's great service to him in undertaking the defence of the theory--a defence which his own hatred of controversy and the state of his health made him unwilling to undertake--by laughingly calling him 'my general agent!' while Huxley himself in replying to the critics, declared that he was 'Darwin's bulldog.' Although, at first, Darwin was able to enumerate less than a dozen naturalists who were prepared to accept his views, while influential leaders of thought in science--like Richard Owen in this country and Louis Agassiz in America--were bitterly opposed to them, the theory gradually obtained supporters especially among the younger cultivators of botany, zoology and geology. It is evident that Darwin for some time regarded his 'abstract,' as he called the _Origin of Species_, as only a temporary expedient--one to be superseded by the publication of the much more extended work, designed and commenced long before. Although the _Origin_ was only published late in November 1859, and he was called upon immediately to prepare a second edition, we find that on January 1st, 1860, Darwin began to arrange his materials for dealing with the first great division of his subject, 'the variation of animals and plants under domestication.' So numerous and important were his notes and records of experiments, however, that he soon found that to expand the whole of the 'abstract,' on the same scale, would be an impossible task for any one man, however able and diligent. Unwilling that the results of some of his special researches should be lost, he wisely determined to issue them as separate books. The first of these to appear was that on the _Fertilisation of Orchids_, a beautiful illustration of the relation of insects to flowers in producing crossing. He had been more than twenty years working and experimenting on this subject, his interest in it having been quickened by having read an almost forgotten book of the botanist Sprengel. Almost at the same time, and in following years, he wrote papers for the Linnean Society on dimorphic and trimorphic forms of flowers, and their bearing on the question of cross-fertilisation. These papers were the foundation of his well-known work, _The Different Forms of Flowers on Plants of the same Species_. In the same way, a paper read in 1864 to the Linnean Society was subsequently expanded into _The Movements and Habits of Climbing Plants_. Owing to delays caused by the preparation and publication of these books and frequent interruptions from sickness, the work on variation did not appear till 1868. It was a very extensive piece of work in two volumes, and, at its end, Darwin tentatively propounded a hypothesis to account for the facts of Heredity and Variation to which he gave the name of 'pangenesis.' Charles Darwin had reached the age of fifty, when he wrote the _Origin of Species_. At a very early period in his career, he had resolved that he would never start a new theory or revise an old one after he was sixty; as he used laughingly to say, 'I have seen too many of my friends make fools of themselves by doing that.' But as he approached this 'fatal age,' one more subject of a theoretical and highly controversial nature remained to be dealt with, namely, the question of the application of the theory of natural selection to man, both as regards his physical structure and his intellectual and moral characteristics. Darwin tells us that in 1837 or '38, as soon as he had become 'convinced that species were mutable productions,' he 'could not avoid the belief that man must come under the same law[140].' From that time, he began collecting facts bearing on the question. As each of his children was born, he examined closely the signs of dawning intelligence, and made notes of the manner in which new sensations and passions were exhibited by them. His dog and other animals, for whom he always showed the greatest fondness, were closely watched with the object of noting correspondences between their mental and moral processes and their modes of exhibiting them and our own; while visits were made by him to the Zoological Gardens with the same object. By reading and correspondence also, an enormous mass of notes was collected, and on February 4th, 1868, having seen his great work on Variation under Domestication published, Darwin was able to make the entry in his diary, 'Began work on Man.' As was usual with most of his works, Darwin underestimated the time required to complete it. Through all the years 1867--'68, '69 and '70 we find the entries in his diary 'working at _Descent of Man_,' and only early in the year 1871 was the book finished. His original plan of compressing his notes on the expression of the Emotions into a chapter at the end of the book proved to be impracticable, and the material was reserved for a new work. This work, _The Expression of the Emotions in Man and Animals_, was commenced directly the _Descent of Man_ was out of hand, a rough copy was finished by April 27th, 1871, but the last proofs were not corrected till August 23rd, 1873. In dealing with the question of the origin of the human race, Darwin was led to propound his views concerning Sexual selection, the results of the preferences shown by males and females, respectively, not only among mankind, but in various other animals. It was with respect to some of the conclusions contained in this work that Wallace found himself unable to follow Darwin. Wallace maintained that while man's body could have been developed by Natural Selection, his intellectual and moral nature must have had a different origin. He also declined to adopt the theory of sexual selection, so far as it depends on preferences exhibited by females for beauty in the males. Wallace, however, in some respects has always been disposed to attach more importance to Natural Selection, as the greatest, if not the only factor in evolution, than Darwin himself. It will be seen that although Darwin had in all probability thought out all his important theoretical conclusions before 1869, when he reached the 'fatal age,' yet, owing to various delays, the books, in which he embodied his views, had not all appeared till more than four years later. Lyell, who was a convinced evolutionist before the publication of the _Principles of Geology_, as is shown by his letters,--and the fact is strongly insisted on both by Huxley and Haeckel[141],--was slow in coming into _complete_ agreement with Darwin concerning the theory of Natural Selection. While he followed his friend's investigations with the deepest interest, his less sanguine nature led him often to despair of the possibility of solving 'the mystery of mysteries.' As Darwin wrote only a year before his own death, Lyell 'would advance all _possible_ objections to my suggestions, and _even after these were exhausted_ would long _remain dubious_[142].' It is evident from the correspondence that Darwin was at times tempted to become impatient with the friend, for whose advocacy of his views he so deeply longed. Fourteen years after the publication of the _Origin of Species_, however, Lyell, in his _Antiquity of Man_, gave in his adhesion to Darwin's theory but, even then, not in the unqualified manner that the latter desired. Yet I have reason to know that some years before his death, Lyell was able to assure his friend of his _complete_ agreement, and Darwin, six years after the loss of his friend, wrote, 'His candour was highly remarkable. He exhibited this by becoming a convert to the Descent theory, though he had gained much fame by opposing Lamarck's views, _and this after he had grown old_.' Darwin adds that Lyell, referring to the '_fatal_ age' of sixty, said 'he hoped that now he might be allowed to live[143]!' When I first came into personal relations with Darwin, after the death of Lyell in 1875, he was in the habit of deprecating any idea of his writing on theoretical questions. He used to talk of 'playing with plants and such things,' and undoubtedly derived the greatest pleasure from his ingenious experimental researches. The result of this 'play' in which Darwin took such delight is seen in his books on the _Power of Movement in Plants_ and _Insectivorous Plants_; full of the records of ingenious experiments and patient observation. It was a great relief to Darwin that his friend Wallace was able in 1871 to undertake the preparation of a work on _The Geographical Distribution of Animals_, for, on many points, the views held by Wallace on this subject were more in accordance with Darwin's own, than were those of Lyell and Hooker. Nevertheless, on all questions connected with the geographical distribution of plants, and the causes by which they were brought about, Darwin always expressed the fullest confidence in Hooker's judgment, and the greatest satisfaction with his results. With regard to another great division of his work, that dealing with the imperfection, but yet great value, of the geological record, Darwin was always anxious, when I met him, to learn of any new discoveries. But he felt that he had done all that was possible in his outline of the subject in the _Origin_, and that he must leave to palaeontologists all over the world the filling in of these outlines. So great was the delight with which he used to hear of new discoveries in palaeontology, that I often recall our conversations in these later days, when so many interesting forms of extinct animal and vegetable life--veritable 'missing links'--are being discovered in all parts of the globe, and wish that he could have known of them. They are indeed 'Facts for Darwin.' Very happy indeed was Charles Darwin in the last years of his useful life, in returning to his oldest 'love'--geology. In studying the action of earthworms he found a geological study in which his rare powers of ingenious experimentation could be employed with profit. His earliest published memoir had dealt with the question, and for more than forty years with dogged perseverance, he had laboured at it from time to time. It was delightful to watch his pleasure as he examined what was going on in the flower-pots full of mould in his study, and when his book was published and favourably received, he rejoiced in it as 'the child of his old age[144].' Charles Darwin's death took place rather more than twenty-two years after the publication of the _Origin of Species_. Before he passed away, he had the satisfaction of knowing that the doctrine of evolution had come to be--mainly through his own great efforts--the accepted creed of all naturalists and that even for the world at large it had lost its imaginary terrors. As Huxley wrote a few days after our sad loss, 'None have fought better, and none have been more fortunate, than Charles Darwin. He found a great truth trodden underfoot, reviled by bigots, and ridiculed by all the world; he lived long enough to see it, chiefly by his own efforts, irrefragably established in science, inseparably incorporated with the common thoughts of men, and only hated and feared by those who would revile, but dare not. What shall a man desire more than this[145]?' More than a quarter of a century has passed since these words were written. How during that period the influence of Darwin's writings on human thought has grown, in an accelerated ratio, will be seen by anyone who will turn the pages of the memorial volume--_Darwin and Modern Science_--published fifty years after the _Origin of Species_. Therein, not only zoologists, botanists and geologists, but physicists, chemists, anthropologists, psychologists, sociologists, philologists, historians--and even politicians and theologians--are found testifying to the important part which Darwin's great work has played, in revolutionising ideas and moulding thought in connexion with all branches of knowledge and speculation. CHAPTER XII THE PLACE OF LYELL AND DARWIN IN HISTORY From the account given in the foregoing pages, it will be seen that--without detracting from the merits of their predecessors or the value of the labours of their contemporaries--we must ascribe the work of establishing on a firm foundation of observation and reasoning the doctrine of evolution--both in the inorganic and the organic world--to the investigations and writings of Lyell and Darwin. Lyell had to oppose the geologists of his day, who led by Buckland in this country and by Cuvier on the continent, were almost, without exception, hopelessly wedded to the doctrines of 'Catastrophism,' and bitterly antagonistic to all ideas savouring of continuity or evolution. And, in the same way, Darwin, at the outset, found himself face to face with a similarly hostile attitude, on the part of biologists, with respect to the mode of appearance of new species of plants and animals. While Darwin doubtless derived his inspiration, and much valuable aid, from the _Principles of Geology_, and its gifted author, yet Lyell, with all his clearness of vision, logical faculty and literary skill, did not possess the strong faith and resolute courage--to say nothing of that wonderful tenacity of purpose and power of research which were such striking characteristics of Darwin--which would have enabled him to do for the organic what he did for the inorganic world. If it be true, as Darwin used to suggest, that the _Origin of Species_ might never have been written had not Lyell first produced the _Principles of Geology_, I believe it is no less certain that the crowning of Lyell's great edifice, by the full application of his principles to the world of living beings, could only have been accomplished by a man possessing, in unique combination, the powers of observation, experiment, reasoning and criticism, joined to unswerving determination, which distinguished Darwin. Starting from Lyell's most advanced post, Darwin boldly advanced into regions in which his friend was unable to lead, and indeed long hesitated to follow. Together, for nearly forty years, the two men--influencing one another 'as iron sharpeneth iron'--thought and communed and worked, aided at all times by the wide knowledge and judicious criticism of the sagacious Hooker; and together the fame of these men will go down to posterity. There is a tendency, when a great man has passed from our midst, to estimate his merits and labours with undiscriminating, and often perhaps exaggerated, admiration; and this excessive praise is too often followed by a reaction, as the result of which the idol of one generation becomes almost commonplace to the next. A still further period is required before the proper position of mental perspective is reached by us, and a just judgment can be formed of the man's real place in history. The reputations of both Lyell and Darwin have, I think, passed through both these two earlier phases of thought, and we may have arrived at the third stage. There was one respect in which both Lyell and Darwin failed to satisfy many both of their contemporaries and successors. Lyell, like Hutton, always deprecated attempts to go back to a 'beginning,' while Darwin, who strongly supported Lyell in his geological views, was equally averse to speculations concerning the 'origin of life on the globe.' Scrope[146], and also Huxley[147] in his earlier days, held the opinion that it was legitimate to assume or imagine a beginning, from which, with ever diminishing energy, the existing 'comparatively quiet conditions,' thought to characterise the present order of the world, would be reached. Both Lyell and Darwin insisted that geology is a historical science, and must be treated as such quite distinct from Cosmogony. And in the end, Huxley accepted the same view[148]. 'Geology,' he asserted, 'is as much a historical science as archaeology.' The sober historian has always had to contend against the traditional belief that 'there were giants on the earth in those days!' The love of the marvellous has always led to the ascription of past events to the work of demigods who were not of like powers and passions with ourselves. Hence the invention of those 'catastrophies'--in which the reputations of deities as well as of men and women have often suffered. It is the same tendency in the human mind which makes it so difficult to conceive of all the changes in the earth's surface-features and its inhabitants being due to similar operations to those still going on around us. Lyell's views have constantly been misrepresented by the belief being ascribed to him that 'the forces operating on the globe have never acted with greater intensity than at the present day.' But his real position in this matter was a frankly 'agnostic' one. 'Bring me evidence,' he would have said, 'that changes have taken place on the globe, which cannot be accounted for by agencies still at work _when operating through sufficiently long periods of time_, and I will abandon my position.' But such evidence was not forthcoming in his day, and I do not think has ever been discovered since. Professor Sollas has very justly said, 'Geology has no need to return to the catastrophism of its youth; in becoming evolutional it does not cease to remain essentially uniformitarian[149].' Alfred Russel Wallace, who has always been as stout a defender of the views of Lyell as he has of those of Darwin, has given me his permission to quote from a letter he wrote me in 1888. After referring to what he regards as the weak and mistaken attacks on Lyell's teachings, 'which have of late years been so general among geologists,' he says:-- 'I have always been surprised when men have advanced the view that volcanic action _must_ have been greater when the earth was hotter, and entirely ignore the numerous indications that both subterranean and meteorological forces, even in Palaeozoic times, were of the same order of magnitude as they are now--and this I have always believed is what Lyell's teaching implies.' I believe that Mr Wallace's expression, adopted from the mathematicians, 'the same order of magnitude,' would have met with Lyell's complete acquiescence. He was not so unwise as to suppose that, in the limited periods of human history, we must necessarily have had experience--even at Krakatoa or 'Skaptar Jokull'--of nature's greatest possible convulsions, but he fought tenaciously against any admission of 'cataclysms' that would belong to a totally different category to those of the present day. Apart from theological objections, the most formidable obstacle to the reception of evolutionary ideas had always been the prejudice against the admission of vast duration of past geological time. It was unfortunate that, even when rational historical criticism had to a great extent neutralised the effect of Archbishop Usher's chronology, the mathematicians and physicists, assuming certain sources of heat in the earth and sun could have been the only possible ones, tried to set a limit to the time at the disposal of the geologist and biologist. Happily the discovery of radio-activity and the new sources of heat opened up by that discovery, have removed those objections, which were like a nightmare to both Geology and Biology. Lyell used to relate the story of a man, who, from a condition of dire poverty, suddenly became the possessor of vast wealth, and when remonstrated with by friends on the inadequacy of a subscription he had offered, the poor fellow exclaimed sadly, 'Ah! you don't know how hard it is to get the chill of poverty out of one's bones.' Geologists and biologists alike have long been the victims of this 'chill of poverty,' with respect to past time. So long as physicists insisted that one hundred millions, or forty millions, or even ten millions of years, must be the limit of geological time, it was not possible to avoid the conclusion stated by Lord Salisbury in 1894, 'Of course, if the mathematicians are right the biologists cannot have what they demand[150].' But now geologists and biologists may alike feel that the liberty with respect to _space_, which is granted ungrudgingly to the astronomer, is no longer withheld from them in regard to _time_. We can say with old Lamarck:-- 'For Nature, Time is nothing. It is never a difficulty, she always has it at her disposal; and it is for her the means by which she has accomplished the greatest as well as the least results. For all the evolution of the earth and of living beings, Nature needs but three elements--Space, Time and Matter[151].' Darwin, equally with Lyell, has suffered from a reaction following on extravagant and uninformed praise of his work. The fields in which he laboured single-handed, have yielded to hundreds of workers in many lands an abundant harvest. New doctrines and improved methods of enquiry have arisen--Mutationism, Mendelism, Weismannism, Neo-Lamarckism, Biometrics, Eugenics and what not--are being diligently exploited. But all of these vigorous growths have their real roots in Darwinism. If we study Darwin's correspondence, and the successive essays in which he embodied his views at different periods, we shall find, variation by mutation (or _per saltum_), the influence of environment, the question of the inheritance of acquired characters and similar problems were constantly present to Darwin's ever open mind, his views upon them changing from time to time, as fresh facts were gathered. No one could sympathise more fully than would Darwin, were he still with us, in these various departures. He was compelled, from want of evidence, to regard variations as spontaneous, but would have heartily welcomed every attempt to discover the laws which govern them; and equally would he have delighted in researches directed to the investigation of the determining factors, controlling conditions and limits of inheritance. The man who so carefully counted and weighed his seeds in botanical experiments, could not but rejoice in the refined mathematical methods now being applied to biological problems. Let us not 'in looking at the trees, lose sight of the wood.' Underlying all the problems, some of them very hotly discussed at the present day, there is the great central principle of Natural Selection--which if not the sole factor in evolution, is undoubtedly a very important and potent one. It is only necessary to compare the present position of the Natural History sciences with that which existed immediately before the publication of the _Origin of Species_, to realise the greatness of Darwin's achievement. The fame of both Lyell and Darwin will endure, and their names will remain as closely linked as were the two men in their lives, the two devoted friends, whose remains found a meet resting-place, almost side by side, in the Abbey of Westminster. Very touching indeed was it to witness the marks of affection between these two great men; an affection which remained undiminished to the end. Lyell was twelve years senior to Darwin, and died seven years before his friend. During the last year of Lyell's life, I spent the summer with him at his home in Forfarshire. How well do I recollect the keenness with which--in spite of a near-sightedness that had increased with age almost to blindness--he still devoted himself to geological work. The 264 note-books, all carefully indexed, were in constant use, and visits were made to all the haunts of his youth, with the frequent pathetic appeal to me, 'You must lend me your eyes.' In spite of age and weakness, he would insist on clambering up the steepest hills to show me where he had found glacial markings, and would eagerly listen to my report on them. But the _great_ delight of those days was the arrival of a letter from Darwin! Lyell was the recipient of many honours, and he declined many more, when he feared that they might interfere with the work to which he had devoted his life, but the distinction he prized most of all was that conferred on him by his life-long friend, who used to address him as 'My dear old Master,' and subscribe himself 'Your affectionate pupil.' During the seven years that elapsed after the death of Lyell, I saw Darwin from time to time, for he loved to hear 'what was doing' in his 'favourite science.' On board the _Beagle_, before he had met the man whose life and work were to be so closely linked with his own, he was in the habit of specially treasuring up any 'facts that would interest Mr Lyell'; in middle life he declared that 'when seeing a thing never seen by Lyell, one yet saw it partially through his eyes[152]'; and never, I think, did we meet after the friend was gone, without the oft repeated query, 'What would Lyell have said to that?' These reminiscences of the past, in which I have ventured to indulge, may not inappropriately conclude with a reference to the last interview I was privileged to have with him, who was 'the noblest Roman of them all!' On the occasion of his last visit to London, in December, 1881, Charles Darwin wrote asking me to take lunch with him at his daughter's house, and to have 'a little talk' on geology. Greatly was I surprised at the vigour which he showed on that afternoon, for, contrary to his usual practice, he did not interrupt the conversation to retire and rest for a time, though I suggested the desirability of his doing so, and offered to stay. His brightness and animation, which were perhaps a little forced, struck me as so unusual that I laughingly suggested that he was 'renewing his youth.' Then a slight shade passed over his countenance--but only for a moment--as he told me that he had 'received his warning.' The attack, to which his son has alluded, as being the prelude to the end[153], had occurred during this visit to town; and he intimated to me that he knew his heart was seriously affected. Never shall I forget how, seeing my concern, he insisted on accompanying me to the door, and how, with the ever kindly smile on his countenance, he held my hand in a prolonged grasp, that I sadly felt might perhaps be the last. And so it proved. And now all the world is united in the conviction which Darwin so modestly expressed concerning his own career, 'I believe that I have acted rightly in steadily following and devoting myself to science!' For has not that _devotion_ resulted in a complete reform of the Natural-History Sciences! The doctrine of the 'immutability of species'--like that of 'Catastrophism' in the inorganic world--has been eliminated from the Biological sciences by Darwin, through his _steadily following_ the clues found by him during his South American travels; and continuity is now as much the accepted creed of botanists and zoologists as it is of geologists. As a result of the labours of Darwin, new lines of thought have been opened out, fresh fields of investigation discovered, and the infinite variety among living things has acquired a grander aspect and a special significance. Very justly, then, has Darwin been universally acclaimed as 'the Newton of Natural History.' NOTES In the following references, L.L.L. indicates the "Life and Letters of Sir Charles Lyell" by Mrs K. Lyell (1881), D.L.L. the "Life and Letters of Charles Darwin" by F. Darwin (1887), M.L.D. "More Letters of Charles Darwin" edited by F. Darwin and A. C. Seward (1903), and H.C.E. Huxley's "Collected Essays." [1] The Darwin-Wallace Celebration, Linn. Soc. (1908), p. 10. [2] Darwin and Modern Science (1909), pp. 152-170. [3] Pope, Essay on Man, Ep. I. lines 111-2. [4] Genesis, Chap. XXX. verses 31-43. [5] Brit. Assoc. Rep. 1900 (Bradford), pp. 916-920. [6] _Ibid._ 1909 (Winnipeg), pp. 491-493. [7] L.L.L. Vol. I. p. 468. [8] Origin of Species, Chap. XV. end. [9] Milton, Paradise Lost, Bk. VII. lines 454-466. [10] Edinb. Rev. LXIX. (July 1839), pp. 446-465. [11] Principles of Geology, Vol. I. (1830), p. 61. [12] Zittel, Hist. of Geol. &c. Eng. transl. p. 72. [13] Quart. Rev. Vol. XLVIII. (March 1832), p. 126. [14] Brit. Assoc. Rep. 1866 (Nottingham). [15] H.C.E. Vol. VIII. p. 315. [16] _Ibid._ p. 190. [17] D.L.L. Vol. II. pp. 179-204. [18] H.C.E. Vol. V. p. 101. [19] D.L.L. Vol. II. p. 190. [20] Edinb. Rev. Vol. LXIX. (July 1839), p. 455 _note_. [21] 'Theory of the Earth,' Vol. II. p. 67. [22] L.L.L. Vol. I. p. 272. [23] Brit. Assoc. Rep. 1833 (Cambridge), pp. 365-414. [24] Outlines of the Geology of England and Wales, p. xliv. [25] Illustrations of the Huttonian Theory, p. iii. [26] Edinb. Rev. LXIX. (July 1839), p. 455 _note_. [27] _Ibid._ [28] Zittel, Hist. of Geol. &c. Eng. transl. p. 141. [29] Considerations on Volcanoes, &c. (1825), pp. iv-vi. [30] Volcanoes of Central France, 2nd Ed. (1858), p. vii. [31] See Quart. Rev. Vol. XXXVI. (Oct. 1827), pp. 437-485. [32] L.L.L. Vol. I. p. 46. [33] Principles of Geology, Vol. II. 2nd Ed. [34] L.L.L. Vol. II. pp. 47-8. [35] _Ibid._ Vol. I. p. 268. [36] Environs de Paris (1811), p. 56. [37] Trans. Geol. Soc. 2nd Ser. Vol. II. pp. 73-96. [38] See Mantell's Geology of the Isle of Wight and L.L.L. Vol. I. pp. 114-122. [39] Hist. of Geol. &c. Eng. transl. p. 188. [40] L.L.L. Vol. I. p. 173. [41] British Critic and Theological Review (1830), p. 7 of the review. [42] L.L.L. Vol. I. p. 177. [43] Preface to Vol. III. of the 'Principles' (1833), p. vii. [44] L.L.L. Vol. I. pp. 233-4. [45] Charles Lyell and Modern Geology (1898), p. 214. [46] Proc. Geol. Soc. Vol. I. p. 374. [47] L.L.L. Vol. I. p. 196. [48] _Ibid._ Vol. I. p. 197. [49] Proc. Geol. Soc. Vol. I. pp. 145-9. [50] L.L.L. Vol. I. p. 253. [51] _Ibid._ Vol. I. p. 234. [52] _Ibid._ Vol. I. p. 271. [53] _Ibid._ Vol. I. p. 270. [54] _Ibid._ Vol. I. p. 271. [55] Quart. Rev. Vol. XLIII. (Oct. 1830), pp. 411-469 and Vol. LIII. (Sept. 1835), pp. 406-448. Both these reviews are by Scrope. The Review of the 2nd Vol. of the 'Principles,' Q.R. Vol. XLVII. (March 1832), pp. 103-132 is by Whewell. [56] L.L.L. Vol. I. p. 270. [57] _Ibid._ Vol. I. pp. 260-1. [58] _Ibid._ Vol. I. p. 314. [59] _Ibid._ Vol. I. p. 165. [60] M.L.D. Vol. II. p. 232 and D.L.L. Vol. II. p. 190. [61] L.L.L. Vol. I. pp. 316-7. [62] Proc. Geol. Soc. Vol. I. pp. 302-3. [63] L.L.L. Vol. II. p. 41. [64] See also D.L.L. Vol. I. pp. 72-3. [65] Nineteenth Century, Oct. 1895, and Controverted Questions in Geology (1895), pp. 1-18. [66] M.L.D. Vol. II. p. 117. [67] D.L.L. Vol. I. pp. 337-8 and p. 342. [68] Origin of Species, Chap. X. See also Darwin and Modern Science, pp. 337-385. [69] D.L.L. Vol. I. pp. 341-2. [70] L.L.L. Vol. II. p. 44. [71] D.L.L. Vol. I. p. 296. [72] _Ibid._ p. 72. [73] _Ibid._ p. 71. [74] A. R. Wallace, 'My Life, &c.' (1905), Vol. I. p. 433. [75] The Darwin-Wallace Celebration, Linn. Soc. (1908), p. 118. [76] L.L.L. Vol. II. p. 459. [77] Report of lecture at Forrester's Hall. [78] H.C.E. Vol. VIII. p. 312. [79] D.L.L. Vol. II. p. 190. [80] L.L.L. Vol. II. pp. 2, 3. [81] _Ibid._ Vol. II. p. 36. [82] _Ibid._ Vol. II. p. 5. [83] D.L.L. Vol. I. p. 94. [84] L.L.L. Vol. I. pp. 417-8. [85] H. F. Osborn, 'From the Greeks to Darwin' (1894), p. 165. [86] _Loc. cit._ pp. 467-469. [87] L.L.L. Vol. I. p. 168. [88] _Ibid._ Vol. II. p. 365. [89] D.L.L. Vol. II. pp. 23, 29, 39. [90] _Ibid._ Vol. III. p. 15 (see also pp. 11-14). [91] 'Origin of Species,' 6th Ed. (1875), p. xiv. [92] 'Darwin and Modern Science,' p. 125. [93] 'Origin of Species,' 6th Ed. (1875), pp. xvi, xvii. [94] M.L.D. Vol. I. p. 3. [95] D.L.L. Vol. I. p. 41. [96] _Ibid._ Vol. I. p. 41. [97] _Ibid._ Vol. I. p. 52. [98] _Ibid._ Vol. I. p. 58. [99] _Ibid._ Vol. I. p. 58. [100] H.C.E. Vol. II. p. 271. [101] D.L.L. Vol. I. p. 73. [102] _Ibid._ Vol. I. p. 263. [103] _Ibid._ Vol. I. p. 38. [104] H.C.E. Vol. II. p. 20. [105] D.L.L. Vol. I. p. 275. [106] _Ibid._ Vol. I. p. 83. [107] _Ibid._ Vol. II. pp. 5-10. [108] H.C.E. Vol. II. p. 71. [109] D.L.L. Vol. I. p. 47. [110] _Ibid._ Vol. I. p. 84. [111] Macmillan's Magazine, Feb. 1888, p. 241. [112] My Life, &c. Vol. I. p. 355. [113] Darwin-Wallace Celebration, Linn. Soc. (1908), pp. 6-7. [114] _Ibid._ pp. 14-16. [115] D.L.L. Vol. II. pp. 116-7. [116] 'Contributions to the Theory of Natural Selection' (1871), Preface, pp. iv, v. [117] Darwin-Wallace Celebration, Linn. Soc. (1908), p. 7. [118] _Ibid._ p. 7. [119] D.L.L. Vol. I. p. 66. [120] _Ibid._ Vol. I. pp. 62-3. [121] _Ibid._ Vol. I. p. 66. [122] _Ibid._ Vol. I. p. 66. [123] D.L.L. Vol. I. p. 83. [124] _Ibid._ Vol. I. p. 84. [125] 'The Foundations of the Origin of Species' (1909), p. xv. [126] Letter to A. R. Wallace, Christ's Coll. Mag. Vol. XXIII. (1909), p. 229. [127] D.L.L. Vol. II. pp. 16-18. [128] _Ibid._ Vol. I. p. 347. [129] D.L.L. Vol. II. pp. 19-21. [130] Huxley's Life and Letters (1900), Vol. I. p. 94. [131] D.L.L. Vol. I. p. 83. [132] Science Progress, Vol. III. (1908), pp. 537-542. [133] D.L.L. Vol. II. p. 160. [134] H.C.E. Vol. II. pp. 227-243. [135] D.L.L. Vol. II. pp. 179-204. [136] _Ibid._ Vol. II. p. 255. [137] The Review is republished in H.C.E. Vol. II. pp. 1-21. [138] Huxley's Life and Letters, Vol. I. pp. 179-189. [139] D.L.L. Vol. II. p. 185. [140] _Ibid._ Vol. I. p. 93. [141] See Haeckel's 'History of Creation.' [142] D.L.L. Vol. I. p. 71. [143] _Ibid._ Vol. I. p. 72. [144] D.L.L. Vol. I. p. 98; Vol. III. pp. 217-218. [145] H.C.E. Vol. II. p. 247. [146] Quart. Rev. XLIII. pp. 464-467 and Vol. LIII. pp. 446-448. [147] H.C.E. Vol. VIII. p. 315. [148] H.C.E. Vol. V. p. 99. [149] The Age of the Earth and other Geological Studies, p. 322. [150] Brit. Assoc. Rep. 1894 (Oxford), p. 13. [151] 'Hydrogéologie,' p. 67. [152] M.L.D. Vol. II. p. 117. [153] D.L.L. Vol. III. p. 356. INDEX Adaptation, in relation to divergence of species, Darwin's recognition of, 108, 109 Agriculturalists, ideas of creation, 5, 6 ARNOLD, MATTHEW, on Lucretius and Darwin, 3, 4 Auvergne, N. Desmarest on, 17; Scrope on, 35; visited by Lyell and Murchison, 56, 57; their memoir on, 58 'Beagle,' H.M.S., Darwin's voyage in, 98, 99; narrative of, 106 BONNEY, T. G., estimate of amount of Lyell's travels by, 56, 57 Botanical works of Darwin, 141 _British Critic_, Whewell's review of Lyell in, 53 BRODERIP, W. J., aid given to Lyell by, 65; Vol. II. of _Principles_ dedicated to, 65 BROWN, ROBERT, assistance to Lyell by, 47 BUCKLAND, Dr, on infant Geological Society, 26; champion of 'Catastrophism' in England, 27; his eccentricity, 42-44; 'Equestrian Geology' of, 28; influence on Lyell, 34, 44; 2nd edition of Vol. I. of _Principles_ dedicated to, 44; his opposition to Lyell, 71 Cambridge, Darwin at, 97, 98 CANDOLLE, A. P. DE, on struggle for existence, 107 Catastrophism, origin of idea of, 14, 15; defined, 22; origin of term, 22; connexion with orthodoxy, 21; championed by Buckland, Sedgwick &c., 27; by Cuvier, 31, 50, 102; opposition by Lyell and Darwin to, 105 Centres of Creation, Lyell's views on, 65 CHAMBERS, ROBERT, publishes _Vestiges of Creation_, 92; his reasons for anonymity, 93 Chemists, part played in early days of Geological Society by, 26 Christ's College, Cambridge, the home of Milton and Darwin, 13; of Paley, 108 CLODD, E., his _Pioneers of Evolution_, 16 Continuity, term for Evolution suggested by Grove, 23 CONYBEARE, W. D., advocacy of Catastrophism, 27; criticism of Hutton, 28; misconception of Hutton, 29; on formation of Thames Valley, 58; friendship with Lyell, 69 Creation, legends of, 5-7; use of term by Lyell and Darwin, 11; contrast of their views with those of Milton, 12, 13 Criticisms of the _Principles of Geology_, 68, 69, 70, 71; of the _Origin of Species_, 132-139 CUVIER, his strong support of Catastrophism, 31, 46, 50, 102 DARWIN, CHARLES, nobility of character, 3; his use of term 'Creation,' 11; on grandeur of idea of Evolution, 12; his devotion to Lyell and the _Principles of Geology_, 63, 73-75, 78; his horror of slavery, 76; opposition to Catastrophism, 77; opinion of Lamarck's works, 90, 91: on the _Vestiges of Creation_, 94; his dislike for speculation, 101; his optimism and courage, 77; his birth and education, 95, 96; life at Edinburgh, 97; at Cambridge, 97, 98; voyage in the 'Beagle,' 99, 100; first awakening to the idea of Evolution, 102, 104; work with Lyell at Geological Society, 105; begins 'species work,' 106; influence of Malthus's work on, 107; intercourse with Wallace, 113; action in respect to theory, 128, 129; his first literary ambitions, 116; difficulties of work caused by ill-health, 117, 118, 119; his loss of appreciation for music and literature, and its cause, 134, 135; later writings on Evolution, 141, 144; his declining years, 147, 158, 159; his death, 147; present position of his theory of Natural Selection, 155, 156, 159 DARWIN, ERASMUS, his independent conception of Lamarckism, 91, 92; absence of influence on his grandson, 95, 101 DARWIN, ERASMUS (the younger), advice given to Charles on publication, 122 DARWIN, FRANCIS, edited _Life and Letters_ &c., 121; extracts from C.D.'s note-books &c., and _Foundations of the Origin of Species_, 123; on his father's health, 118 DARWIN, Mrs, her care of her husband's health, 118; read proofs of _Origin of Species_, 132 DAUBENY, C. G. B., assists Lyell in his researches, 47 DE LA BECHE, H., his attitude with respect to evolution, 71 DESHAYES, G. B., assists Lyell in conchological work, 66 DESMAREST, N., work in Auvergne, 17; evolutionary views of, 17, 20 Earthworms, Darwin's work on, 147 Edinburgh, Darwin's life at, 97; Wernerian Society at, founded by Jameson, 21, 25 Egypt, idea of inorganic evolution originated in, 15 Entomology, influence of, on Lyell, 42, 57; on Darwin, 96; on Wallace, 110 'Equestrian Geology,' popularity of, at Oxford, 27; at Cambridge, 28 Evolution, in _organic_ and _inorganic_ world, 14; how ideas originated, 15-16, 82, 83; revolution effected by, 1, 32, 159; causes of opposition to, 20, 21, 155; opposition of Sedgwick and Whewell, 83; support of Herschel, 83 Euclid, influence on Darwin, 108 FARADAY, M., assistance given to Lyell by, 47 FITTON, Dr, on supposed indebtedness of Hutton to Generelli, 18; and of Lyell to Hutton, 18; on causes of Hutton's failure to reform geology, 23, 25; his attitude towards Lyell's views, 30, 71 Fluvialists, 58 FORBES, DAVID, intercourse with Darwin, 119 Fossil bones, discovery of, in South America first suggests to Darwin mutability of species, 102 _Foundations of the Origin of Species_, 123 FRAZER, J. G., on legends of creation, 5, 7 Galapagos Islands, influence of study of fauna on Darwin, 104 GENERELLI, advocacy of Evolution, 17, 20 Geographical distribution, Lyell on, 65; Wallace on, 146 Geological Society, foundation of, 25; early history, 26; connexion of Lyell with, 44, 71: of Darwin, 100, 105: of Scrope, 50; discussions on rival doctrines at, 24, 25, 29, 30, 60, 76, 77, 105 Geology, Darwin's interest in, 96, 99, 124, 147, 158 GIBBON, his influence on Lyell, 52, 67 GREENOUGH, G. B., founds Geological Society and first President, 26; his strong support of Wernerism, 26, 29 GROVE, R., suggests term 'Continuity,' 23 GÜNTHER, Dr, his estimate of number of species of animals, 10 HAECKEL, E., credits Lyell with early conviction of Evolution, 84 HENSLOW, J. S., friendship for and help of Darwin, 97, 98, 99; opposition to Evolution, 27, 72 Heredity, early recognition of importance, 9 HERSCHEL, J., belief in Evolution, 12, 71; correspondence with Lyell, 12, 83, 85 HOFF, C. VON, influence of his works on Lyell, 49 HOOKER, J. D., friendship with Lyell's father, 126; voyage to Antarctic with Ross, 126; introduction to Darwin, 126; correspondence with, 127; assistance to Darwin, 126; advice to, 129; on origin of Australian flora, 139; friendship with Lyell, 79, 126 HUTTON, his _Theory of the Earth_, 17, 18, 19, 20; rarity of the book, 30; small influence of, 21; supposed infidelity and persecution of, 21, 22, 25, 69; Lyell's mistaken views on, 54; difference of his theory from Lyell's, 53 HUXLEY, T. H., early views on distinction of Uniformitarianism and Evolution, 23; later view of identity, 23, 24; influence of Darwin on, 24, 127, 144; on 1st edition of Principles, 67, 80, 81; argues for Lyell's belief in Evolution, 84; reviews _Origin of Species_, 136, 137; reply to Bishop of Oxford, 138; defence of Darwinism, 140; on Darwin's death, 147, 148; on Lyell's death, 80 Hybridity, Lyell's discussion on, 65, 103 Hypotheses of Creation, twofold character of, 5-8 Ideas _v._ Actions, Wallace on, 4 Independent discovery of Natural Selection by Wallace, 113; Darwin's letter on, 113 Italian geologists, their anticipation of evolutionary ideas, 17 JACOB, his frauds based on ideas of heredity and variation, 9 JAMESON, R., founds Wernerian Society 1807, 25; influence on Darwin, 97 _Journal of Researches_, by Darwin, 106; dedicated to Lyell, 72 King's College, London, Lyell professor at, 65, 66 Kinnordy, Lyell at, 42, 43, 46 KIRWAN, DE LUC, and WILLIAMS, opposition to Hutton, 25 LAMARCK, his _Hydrogéologie_, 87; _Philosophie Zoologique_, 88; Lyell's admiration of, 64, 89; criticism of theory, 64, 90; views of Darwin on, 90, 91; on geological time, 155 Lectures by Lyell, 65, 66 Linnean Society, papers of Darwin and Wallace at, 112, 129, 130 Literature, Lyell and, 52, 67; Darwin and, 116, 117, 120; his loss of interest in, 134, 135 LOCKHART and _Quarterly Review_, 60 LUCRETIUS, belief in Evolution, 3, 4 LYELL, CHARLES, use of term 'Creation,' 11; on grandeur of idea of Evolution, 12; birth and ancestry, 41; education, 34, 42; influence of Buckland on, 34, 42-44; on Cuvier, 46; change of views not due to Hutton's works, 45; but to travel and observation, 45; in East Anglia, 45; in Strathmore, 46, 47; abandons career as barrister for geology, 48; work with Dr Mantell, 48; visits to Continent, 48; influence of von Hoff's works, 49; of Scrope, 50; his remarks on Hutton's supposed heresies, 51, 54; influence of Gibbon on his literary style, 52; praise of Hutton and Playfair at later date, 53; review of Scrope's book on Auvergne, 56; visit to Auvergne with Murchison, 56; advocacy of travel for geologists, 56; journeys in Italy, 58; Lyell on Murchison, 57; Murchison on Lyell, 58; Lyell's avoidance of controversy, 63; differences of opinion with Scrope, 62, 63; attention to literary style, 65; professorship at King's College, London, 65, 69; lectures, 66; controversies at Geological Society, 71; aid of Darwin in discussions, 71; his friendship with Darwin, 73, 104, 105; his extreme caution, 75-77; candour in finally accepting Natural Selection, 77; opposition to his views, 83, 84; his belief in Evolution at an early date, 81, 84-86; his anticipation of 'Mimicry,' 85, 86; his action in Darwin-Wallace episode, 113, 129; induces Darwin to commence writing his work, 128; his attitude towards theory of Natural Selection, 139, 140, 145; great influence of Lyell's works on Darwin and Evolution, 150; misrepresentation of his views, 152-154; his declining years, 157; last hours, 80; Hooker's tribute to his memory, 79, 80 LYELL, CHARLES (the elder), botanist and student of Dante, 41; intercourse with the Hookers, 126 MALTHUS, _On Population_, influence of work on Darwin, 107; on Wallace, 112 Man, descent of, Darwin's work on, 142, 144; Wallace's views on, 144 MANTELL, Lyell's researches with, 48; correspondence with, 55, 89 MATTHEW, P., anticipation of theory of Natural Selection, 92 MILTON, description of creation, 13; Darwin's early love of his poetry, 134; at Christ's College, Cambridge, 13 Mimicry, doctrine of, Lyell's early recognition of importance, 85, 86 _Modern Science, Darwin and_, 148 MURCHISON, accompanies Lyell to Auvergne, 56; opinion of Lyell, 57; Lyell's opinion of, 57, 58; 3rd Vol. of _Principles_ dedicated to, 66; correspondence with, 59 MURRAY, JOHN, and _Quarterly Review_, 60; publishes Lyell's works, 60; publishes Darwin's works, 130; his reminiscences of Darwin, 132 Music, Darwin's loss of power to appreciate, and its cause, 134, 135 Natural Selection, theory of, defined by Huxley, 106; forestalled by Wells, Matthew &c., 18, 19; first conception of by Darwin, 107; by Wallace, 112 'Neptunism' or 'Wernerism' and Catastrophism, 18 NEWTON, Professor A., on vague hopes of solution of 'species question' before Darwin, 94, 109 _Origin of Species_, first idea of, 121; plan proposed to follow _Principles_, 123; first sketch of 1842, enlarged draft of 1844, commencement of great treatise on Evolution in 1856, interruption by arrival of Wallace's papers, 128, 129; the 'Abstract' or _Origin of Species_ commenced, 130; finished, 131; reception of, 132-139; influence of, 1, 159 OSBORN, H. F., his _From the Greeks to Darwin_, 16; on Lamarck, 87 PALEY, his influence on Darwin, 108 PHILLIPS, JOHN, his attitude towards Lyell's views, 30, 71 Philosophers, on Evolution, 16, 82 PLAYFAIR, JOHN, his _Illustrations of the Huttonian Theory_, 29; explains the causes of Hutton's failure, 30 'Plutonism,' 'Vulcanism,' or 'Huttonism,' 18 Poets and Evolution, 16 PRESTWICH, Sir J., opposition to Lyell's views, 72 PREVOST, CONSTANT, aid to Lyell, 50; opposition to Cuvier, 50 PRIESTLEY, persecution of, 21, 69 _Principles of Geology_, first idea of, 55; early draft sent to publisher in 1827, 56; withdrawn and rewritten in 1830, 56; issue of first volume, 63; success, 64; review by Scrope, 60-62; decision to confine Vol. II. to Organic Evolution, 65; 3rd volume, classification of Tertiaries and Metamorphic theory, 66; later editions, 66; _Elements, Manual and Student's elements_, 67; success of work, 67; Darwin's opinion on, 67; of Huxley, 67, 80, 81; Wallace on, 79; criticisms of, 68, 69, 70, 71 PYTHAGORAS, his evolutionary ideas, 16 _Quarterly Review_, articles by Lyell, 56, 89; by Scrope, 60, 62 Reviews, of the _Principles_ by Scrope, 56, 89; by Whewell, 22, 53; of the _Origin_ by Huxley, 136, 137 SCROPE, G. POULETT, education, 34; travels, 34; work in Auvergne, 35; in Italy, 35; delay in publishing, 35; work on volcanoes, 36; his just views on Evolution, 37-39; cause of want of recognition of his work, 39, 40; devotion to politics, 40; reviews of _Principles_, 41, 61; correspondence with and influence on Lyell, 50, 61; his differences of opinion from Lyell, 62, 63, 151; effects of his review, 64 SEDGWICK, A., advocates Catastrophism, 27, 28; opposition to Hutton, influence on Scrope, 34; on Darwin, 98; opposition to Lyell, 83; weakening of opposition to, 58; on _Principles_, 70, 71; dislike to Evolution, 83 SHIPLEY, A. E., estimate of number of species of animals, 10 Slavery, views of Lyell and Darwin, 76 SMITH, W., influence of his teaching on Geological Society, 27 SOLLAS, W. J., on Evolution and Uniformitarianism, 152, 153 Species, origin of idea of, 9; number of species of animals, 10; of plants, 11 Struggle for existence, Lyell on, 103, 107; de Candolle on, 107 _Theory of the Earth_, Hutton's, 17; Scrope's, 36 THOMPSON, G. P., _see_ Scrope, 33 Time geological, Lyell on, 154; Lamarck on, 155 TOLLET, Miss G., aids Darwin in revising _Origin of Species_, 132 Uniformitarianism, origin of the term, 14, 15, 22 Uniformity (or Continuity), Lyell's real views on, 62, 63; misconceptions of his views on, 151, 152, 155 University of London, Lyell's connexion with, 59, 65 Variation, early recognition of its importance, 9; Lyell's discussion of, 64, 103; Darwin's work on, 141 _Vestiges of Creation_, influence of, 93; Darwin on, 94; Wallace on, 110 VINES, S. H., estimate of number of species of plants, 10 Volcanoes, Scrope on, 36 Vulcanism, _see_ Plutonism &c., 18 WALLACE, ALFRED RUSSEL, on ideas and actions, 4; his early life, 110; in South America, 110; in Malay Archipelago, 110; influence of _Principles_ on, 79, 110; speculations at Sarawak, 111; influence of Malthus on, 112; conception of idea of Natural Selection, 111, 112; ignorance of Darwin's views, 112; statement on his relation to Darwin, 113, 114; his magnanimity, 114; on geographical distribution of animals, 146; his defence of Lyell's principle of Uniformity, 153 WELLS, Dr, his anticipation of theory of Natural Selection, 92 WERNER, success of his teachings, 21, 26, 27; his influence on early geologists, 26 Wernerian Society, founded, 1807, by Jameson, 21, 25 Wernerism, 18 WHEWELL, Dr, contrast of doctrines of Hutton and Lyell, 22, 53; originates terms 'Catastrophism,' 'Uniformitarianism,' 22; and 'Geological Dynamics,' 70; reviews _Principles_, 53; opposition to Evolution, 83 World, small part known to ancients, 9 Worms, Darwin's work on, 147 ZITTEL, K. VON, on Hutton's work, 19; on von Hoff and Lyell, 50 _Zoonomia_ of Erasmus Darwin, 101 Cambridge: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS * * * * * Transcribers' note: General: Inconsistent capitalisation of Von in Von Hoff as in original General: No period (full stop) after Mr, Mrs, Dr as in original Page 24: ) added after 'uniformitarianism' to create matching pair Pages 33, 171: Inconsistent spelling of Thomson/Thompson as in original. Page 59: Missing anchor [50] added after dogmatise as this seemed the most likely place Page 80: " changed to ' after [76] to create matching pair Page 89: his changed to His in his theories delighted me Page 94: eniment corrected to eminent Page 102: re-stocked standardised to restocked Page 111: . added after September 1855 Page 149: . added after plants and animals Page 157: lifelong standardised to life-long Page 167: Wernerianism standardised to Wernerism; index entry for Herschel, J., correspondence with Lyell corrected from non-existent page 183 to page 12 
44582	----	YALE UNIVERSITY MRS. HEPSA ELY SILLIMAN MEMORIAL LECTURES PROBLEMS OF GENETICS SILLIMAN MEMORIAL LECTURES PUBLISHED BY YALE UNIVERSITY PRESS ELECTRICITY AND MATTER. _By_ JOSEPH JOHN THOMSON, D.SC., LL.D., PH.D., F.R.S., _Fellow of Trinity College, Cambridge, Cavendish Professor of Experimental Physics, Cambridge_. _Price $1.25 net; postage 10 cents extra._ THE INTEGRATIVE ACTION OF THE NERVOUS SYSTEM. _By_ CHARLES S. SHERRINGTON, D.SC., M.D., HON. LL.D., TOR., F.R.S., _Holt Professor of Physiology in the University of Liverpool_. _Price $3.50 net; postage 25 cents extra._ RADIOACTIVE TRANSFORMATIONS. _By_ ERNEST RUTHERFORD, D.SC., LL.D., F.R.S., _Macdonald Professor of Physics, McGill University_. _Price $3.50 net; postage 22 cents extra._ EXPERIMENTAL AND THEORETICAL APPLICATIONS OF THERMODYNAMICS TO CHEMISTRY. _By_ DR. WALTHER NERNST, _Professor and Director of the Institute of Physical Chemistry in the University of Berlin_. _Price $1.25 net; postage 10 cents extra._ THE PROBLEMS OF GENETICS. _By_ WILLIAM BATESON, M.A., F.R.S., _Director of the John Innes Horticultural Institution, Merton Park, Surrey, England_. _Price $4.00 net; postage 25 cents extra._ STELLAR MOTIONS. WITH SPECIAL REFERENCE TO MOTIONS DETERMINED BY MEANS OF THE SPECTROGRAPH. _By_ WILLIAM WALLACE CAMPBELL, SC.D., LL.D., _Director of the Lick Observatory, University of California_. _Price $4.00 net; postage 30 cents extra._ THEORIES OF SOLUTIONS. _By_ SVANTE AUGUST ARRHENIUS, PH.D., SC.D., M.D., _Director of the Physico-Chemical Department of the Nobel Institute, Stockholm, Sweden_. _Price $2.25 net; postage 15 cents extra._ IRRITABILITY. A PHYSIOLOGICAL ANALYSIS OF THE GENERAL EFFECT OF STIMULI IN LIVING SUBSTANCES. _By_ MAX VERWORN, _Professor at Bonn Physiological Institute_. _Price $3.50 net; postage 20 cents extra._ THE EVOLUTION OF MODERN MEDICINE. _By_ SIR WILLIAM OSLER, BART., M.D., LL.D., SC.D., _Regius Professor of Medicine, Oxford University_. _Price $3.00 net; postage 40 cents extra._ PROBLEMS OF GENETICS BY WILLIAM BATESON, M.A., F.R.S. DIRECTOR OF THE JOHN INNES HORTICULTURAL INSTITUTION, HON. FELLOW OF ST. JOHN'S COLLEGE, CAMBRIDGE, AND FORMERLY PROFESSOR OF BIOLOGY IN THE UNIVERSITY _WITH ILLUSTRATIONS_ [Illustration] NEW HAVEN: YALE UNIVERSITY PRESS LONDON: HUMPHREY MILFORD OXFORD UNIVERSITY PRESS MCMXIII Copyright, 1913 By YALE UNIVERSITY First printed August, 1913, 1000 copies [** Transcriber's Note: Underscores "_" before and after a word or phrase indicate ITALICS in the original text. Hyphenation was used inconsistently by the author and has been left as in the original text. ] THE SILLIMAN FOUNDATION In the year 1883 a legacy of about eighty-five thousand dollars was left to the President and Fellows of Yale College in the city of New Haven, to be held in trust, as a gift from her children, in memory of their beloved and honored mother, Mrs. Hepsa Ely Silliman. On this foundation Yale College was requested and directed to establish an annual course of lectures designed to illustrate the presence and providence, the wisdom and goodness of God, as manifested in the natural and moral world. These were to be designated as the Mrs. Hepsa Ely Silliman Memorial Lectures. It was the belief of the testator that any orderly presentation of the facts of nature or history contributed to the end of this foundation more effectively than any attempt to emphasize the elements of doctrine or of creed; and he therefore provided that lectures on dogmatic or polemical theology should be excluded from the scope of this foundation, and that the subjects should be selected rather from the domains of natural science and history, giving special prominence to astronomy, chemistry, geology, and anatomy. It was further directed that each annual course should be made the basis of a volume to form part of a series constituting a memorial to Mrs. Silliman. The memorial fund came into the possession of the Corporation of Yale University in the year 1901; and the present volume constitutes the fifth of the series of memorial lectures. PREFACE This book gives the substance of a series of lectures delivered in Yale University, where I had the privilege of holding the office of Silliman Lecturer in 1907. The delay in publication was brought about by a variety of causes. Inasmuch as the purpose of the lectures is to discuss some of the wider problems of biology in the light of knowledge acquired by Mendelian methods of analysis, it was essential that a fairly full account of the conclusions established by them should first be undertaken and I therefore postponed the present work till a book on Mendel's Principles had been completed. On attempting a more general discussion of the bearing of the phenomena on the theory of Evolution, I found myself continually hindered by the consciousness that such treatment is premature, and by doubt whether it were not better that the debate should for the present stand indefinitely adjourned. That species have come into existence by an evolutionary process no one seriously doubts; but few who are familiar with the facts that genetic research has revealed are now inclined to speculate as to the manner by which the process has been accomplished. Our knowledge of the nature and properties of living things is far too meagre to justify any such attempts. Suggestions of course can be made: though, however, these ideas may have a stimulating value in the lecture room, they look weak and thin when set out in print. The work which may one day give them a body has yet to be done. The development of negations is always an ungrateful task apt to be postponed for the positive business of experiment. Such work is happily now going forward in most of the centers of scientific life. Of many of the subjects here treated we already know more than we did in 1907. The delay in production has made it possible to incorporate these new contributions. The book makes no pretence at being a treatise and the number of illustrative cases has been kept within a moderate compass. A good many of the examples have been chosen from American natural history, as being appropriate to a book intended primarily for American readers. The facts are largely given on the authority of others, and I wish to express my gratitude for the abundant assistance received from American colleagues, especially from the staffs of the American Museum in New York, and of the Boston Museum of Natural History. In connexion with the particular subjects personal acknowledgments are made. Dr. F. M. Chapman was so good as to supervise the preparation of the coloured Plate of _Colaptes_, and to authorize the loan of the Plate representing the various forms of _Helminthophila_, which is taken from his _North American Warblers_. I am under obligation to Messrs. Macmillan & Co., for permission to reproduce several figures from _Materials for the Study of Variation_, illustrating subjects which I wished to treat in new associations, and to M. Leduc for leave to use Fig. 9. In conclusion I thank my friends in Yale for the high honour they did me by their invitation to contribute to the series of Silliman Lectures, and for much kindness received during a delightful sojourn in that genial home of learning. TABLE OF CONTENTS. CHAPTER PAGE I. INTRODUCTORY. THE PROBLEM OF SPECIES AND VARIETY 1 II. MERISTIC PHENOMENA 31 III. SEGMENTATION, ORGANIC AND MECHANICAL 60 IV. THE CLASSIFICATION OF VARIATION AND THE NATURE OF SUBSTANTIVE VARIATION 83 NOTE TO CHAPTER IV 94 V. THE MUTATION THEORY 97 NOTE TO CHAPTER V 116 VI. VARIATION AND LOCALITY 118 VII. LOCAL DIFFERENTIATION--_continued_. OVERLAPPING FORMS 146 VIII. LOCALLY DIFFERENTIATED FORMS--_continued_. CLIMATIC VARIETIES 164 IX. THE EFFECTS OF CHANGED CONDITIONS 187 X. THE EFFECTS OF CHANGED CONDITIONS--_continued_. THE CAUSES OF GENETIC VARIATION 212 XI. THE STERILITY OF HYBRIDS. CONCLUDING REMARKS 233 APPENDIX TO CHAPTER X 250 INDEX 251 PROBLEMS OF GENETICS CHAPTER I INTRODUCTORY The purpose of these lectures is to discuss some of the familiar phenomena of biology in the light of modern discoveries. In the last decade of the nineteenth century many of us perceived that if any serious advance was to be made with the group of problems generally spoken of as the Theory of Evolution, methods of investigation must be devised and applied of a kind more direct and more penetrating than those which after the general acceptance of the Darwinian views had been deemed adequate. Such methods obviously were to be found in a critical and exhaustive study of the facts of variation and heredity, upon which all conceptions of evolution are based. To construct a true synthetic theory of Evolution it was necessary that variation and heredity instead of being merely postulated as axioms should be minutely examined as phenomena. Such a study Darwin himself had indeed tentatively begun, but work of a more thorough and comprehensive quality was required. In the conventional view which the orthodoxy of the day prescribed, the terms variation and heredity stood for processes so vague and indefinite that no analytical investigation of them could be contemplated. So soon, however, as systematic inquiry into the natural facts was begun it was at once found that the accepted ideas of variation were unfounded. Variation was seen very frequently to be a definite and specific phenomenon, affecting different forms of life in different ways, but in all its diversity showing manifold and often obvious indications of regularity. This observation was not in its essence novel. Several examples of definite variation had been well known to Darwin and others, but many, especially Darwin himself in his later years, had nevertheless been disposed to depreciate the significance of such facts. They consequently then lapsed into general disparagement. Upon more careful inquiry the abundance of such phenomena proved to be far greater than was currently supposed, and a discussion of their nature brought into prominence a consideration of greater weight, namely that the differences by which these definite or discontinuous variations are constituted again and again approximate to and are comparable with the class of differences by which species are distinguished from each other. The interest of such observations could no longer be denied. The more they were examined the more apparent it became that by means of the facts of variation a new light was obtained on the physiological composition and capabilities of living things. Genetics thus cease to be merely a method of investigating theories of evolution or of the origin of species but provide a novel and hitherto untried instrument by which the nature of the living organism may be explored. Just as in the study of non-living matter science began by regarding the external properties of weight, opacity, colour, hardness, mode of occurrence, etc., noting only such evidences of chemical attributes and powers as chance spontaneously revealed; and much later proceeded to the discovery that these casual manifestations of chemical properties, rightly interpreted, afford a key to the intrinsic nature of the diversity of matter, so in biology, having examined those features of living things which ordinary observations can perceive, we come at last to realize that when studied for their own sake the properties of living organisms in respect of heredity and variation are indications of their inner nature and provide evidences of that nature which can be obtained from no other source. While such ideas were gradually forming in our minds, came the rediscovery of Mendel's work. Investigations which before had only been imagined as desirable now became easy to pursue, and questions as to the genetic inter-relations and compositions of varieties can now be definitely answered. Without prejudice to what the future may disclose whether by way of limitation or extension of Mendelian method, it can be declared with confidence and certainty that we have now the means of beginning an analysis of living organisms, and distinguishing many of the units or factors which essentially determine and cause the development of their several attributes. Briefly put, the essence of Mendelism lies in the discovery of the existence of unit characters or factors. For an account of the Mendelian method, how it is applied and what it has already accomplished, reference must be made to other works.[1] With this part of the subject I shall assume a sufficient acquaintance. In these lectures I have rather set myself the task of considering how certain problems appear when viewed from the standpoint to which the application of these methods has led us. It is indeed somewhat premature to discuss such questions. The work of Mendelian analysis is progressing with great rapidity and anything I can say may very soon be superseded as out of date. Nevertheless a discussion of this kind may be of at least temporary service in directing inquiry to the points of special interest. THE PROBLEM OF SPECIES AND VARIETY Nowhere does our new knowledge of heredity and variation apply more directly than to the problem what is a species and what is a variety? I cannot assert that we are already in a position to answer this important question, but as will presently appear, our mode of attack and the answers we expect to receive are not those that were contemplated by our predecessors. If we glance at the history of the scientific conception of Species we find many signs that it was not till comparatively recent times that the definiteness of species became a strict canon of the scientific faith and that attempts were made to give precise limits to that conception. When the diversity of living things began to be accurately studied in the sixteenth and seventeenth centuries names were applied in the loosest fashion, and in giving a name to an animal or a plant the naturalists of those times had no ulterior intention. Names were bestowed on those creatures about which the writer proposed to speak. When Gesner or Aldrovandi refer to all the kinds of horses, unicorns, dogs, mermaids, etc., which they had seen or read of, giving to each a descriptive name, they do not mean to "elevate" each named kind to "specific rank"; and if anyone had asked them what they meant by a species, it is practically certain that they would have had not the slightest idea what the question might imply, or any suspicion that it raised a fundamental problem of nature. Spontaneous generation being a matter of daily observation, then unquestioned, and supernatural events of all kinds being commonly reported by many witnesses, transmutation of species had no inherent improbability. Matthioli,[2] for instance, did not expect to be charged with heresy when he declared _Stirpium mutatio_ to be of ordinary occurrence. After giving instances of induced modifications he wrote, "Tantum enim in plantis naturae germanitas potest, ut non solum saepe praedictos praestet effectus, sed etiam ut alteram in alteram stirpem facile vertat, ut cassiam in cinnamomum, sisymbrium in mentham, triticum in lolium, hordeum in avenam, et ocymum in serpyllum." I do not know who first emphasized the need for a clear understanding of the sense in which the term species is to be applied. In the second half of the seventeenth century Ray shows some degree of concern on this matter. In the introduction to the _Historia Plantarum_, 1686, he discusses some of the difficulties and lays down the principle that varieties which can be produced from the seed of the same plant are to be regarded as belonging to one species, being, I believe, the first to suggest this definition. That new species can come into existence he denies as inconsistent with Genesis 2, in which it is declared that God finished the work of Creation in six days. Nevertheless he does not wholly discredit the possibility of a "transmutation" of species, such that one species may as an exceptional occurrence give rise by seed to another and nearly allied species. Of such a phenomenon he gives illustrations the authenticity of which he says he is, against his will, compelled to admit. He adds that some might doubt whether in the cases quoted the two forms concerned are really distinct species, but the passage is none the less of value for it shews that the conception of species as being distinct unchangeable entities was not to Ray the dogma sacrosanct and unquestionable which it afterwards became.[3] In the beginning of the eighteenth century Marchant,[4] having observed the sudden appearance of a lacinated variety of _Mercurialis_, makes the suggestion that species in general may have arisen by similar mutations. Indeed from various passages it is manifest that to the authors of the seventeenth and early eighteenth centuries species appeared simply as groups more or less definite, the boundaries of which it was unnecessary to determine with great exactitude. Such views were in accord with the general scientific conception of the time. The mutability of species is for example sometimes likened (see for instance Sharrock, loc. cit.) to the metamorphoses of insects, and it is to be remembered that the search for the Philosopher's Stone by which the transmutation of metals was to be effected had only recently fallen into discredit as a pursuit. The notion indeed of a peculiar, fixed meaning to be attached to species as distinct from variety is I think but rarely to be found categorically expressed in prae-Linnaean writings. But with the appearance of the _Systema Naturae_ a great change supervened. Linnaeus was before all a man of order. Foreseeing the immense practical gain to science that must come from a codification of nomenclature, he invented such a system. It is not in question that Linnaeus did great things for us and made Natural History a manageable and accessible collection of facts instead of a disorderly heap; but orderliness of mind has another side, and inventors and interpreters of systems soon attribute to them a force and a precision which in fact they have not. The systematist is primarily a giver of names, as Ray with his broader views perceived. Linnaeus too in the exordium to the _Systema Naturae_ naively remarks, that he is setting out to continue the work which Adam began in the Golden Age, to give names to the living creatures. Naming however involves very delicate processes of mind and of logic. Carried out by the light of meagre and imperfect knowledge it entails all the mischievous consequences of premature definition, and promotes facile illusions of finality. So was it with the Linnaean system. An interesting piece of biological history might be written respecting the growth and gradual hardening of the conception of Species. To readers of Linnaeus's own writings it is well known that his views cannot be summarized in a few words. Expressed as they were at various times during a long life and in various connexions, they present those divers inconsistencies which commonly reflect a mind retaining the power of development. Nothing certainly could be clearer than the often quoted declaration of the _Philosophia Botanica_, "Species tot numeramus quot diversae formae in principio sunt creatae," with the associated passage "Varietates sunt plantae ejusdem speciei mutatae a caussa quacunque occasionali." Those sayings however do not stand alone. In several places, notably in the famous dissertation on the peloric _Linaria_ he explicitly contemplates the possibility that new species may arise by crossing, declaring nevertheless that he thinks such an event to be improbable. In that essay he refers to Marchant's observation on a laciniate _Mercurialis_, but though he states clearly that that plant should only be regarded as a variety of the normal, he does not express any opinion that the contemporary genesis of new species must be an impossibility. In the later dissertation on Hybrid Plants he returns to the same topic. Again though he states the belief that species cannot be generated by cross-breedings, he treats the subject not as heretical absurdity but as one deserving respectful consideration. The significance of the aphorisms that precede the lectures on the Natural Orders is not easy to apprehend. These are expressed with the utmost formality, and we cannot doubt that in them we have Linnaeus's own words, though for the record we are dependent on the transcripts of his pupils. The text of the first five is as follows: 1. Creator T. O. in primordio vestiit Vegetabile _Medullare_ principiis constitutivis diversi _Corticalis_ unde tot difformia individua, quot _Ordines_ Naturales prognata. 2. _Classicas_ has (1) plantas Omnipotens miscuit inter se, unde tot _Genera_ ordinum, quot inde plantae. 3. _Genericas_ has (2) miscuit Natura, unde tot _Species_ congeneres quot hodie existunt. 4. _Species_ has miscuit Casus, unde totidem quot passim occurrunt, _Varietates_. 5. Suadent haec (1-4) Creatoris leges a simplicibus ad Composita. Naturae leges generationis in hybridis. Hominis leges ex observatis a posteriori. I am not clear as to the parts assigned in the first sentence respectively to the "_Medulla_" and the "_Cortex_," beyond that Linnaeus conceived that multiformity was first brought about by diversity in the "_Cortex_." The passage is rendered still more obscure if read in connection with the essay on "_Generatio Ambigena_," where he expresses the conviction that the _Medulla_ is contributed by the mother, and the _Cortex_ by the father, both in plants and animals.[5] But however that may be, he regards this original diversity as resulting in the constitution of the Natural Orders, each represented by one individual. In the second aphorism the Omnipotent is represented as creating the genera by intermixing the individual _plantae classicae_, or prototypes of the Natural Orders. The third statement is the most remarkable, for in it he declares that Species were formed by the act of Nature, who by inter-mixing the genera produced _Species congeneres_, namely species inside each genus, to the number which now exist. Lastly, Chance or Accident, intermixing the species, produced as many varieties as there are about us. Linnaeus thus evidently regarded the intermixing of an originally limited number of types as the sufficient cause of all subsequent diversity, and it is clear that he draws an antithesis between _Creator_, _Natura_, and _Casus_, assigning to each a special part in the operations. The acts resulting in the formation of genera are obviously regarded as completed within the days of the Creation, but the words do not definitely show that the parts played by Nature and Chance were so limited. Recently also E. L. Greene[6] has called attention to some curious utterances buried in the _Species Plantarum_, in which Linnaeus refers to intermediate and transitional species, using language that even suggests evolutionary proclivities of a modern kind, and it is not easy to interpret them otherwise. Whatever Linnaeus himself believed to be the truth, the effect of his writings was to induce a conviction that the species of animals and plants were immutably fixed. Linnaeus had reduced the whole mass of names to order and the old fantastical transformations with the growth of knowledge had lapsed into discredit; the fixity of species was taken for granted, but not till the overt proclamation of evolutionary doctrine by Lamarck do we find the strenuous and passionate assertions of immutability characteristic of the first half of the nineteenth century. It is not to be supposed that the champions of fixity were unacquainted with varietal differences and with the problem thus created, but in their view these difficulties were apparent merely, and by sufficiently careful observation they supposed that the critical and permanent distinctions of the true species could be discovered, and the impermanent variations detected and set aside. This at all events was the opinion formed by the great body of naturalists at the end of the eighteenth and beginning of the nineteenth centuries, and to all intents and purposes in spite of the growth of evolutionary ideas, it remains the guiding principle of systematists to the present day. There are 'good species' and 'bad species' and the systematists of Europe and America spend most of their time in making and debating them. In some of its aspects the problem of course confronted earlier naturalists. Parkinson for instance (1640) in introducing his treatment of _Hieracium_ wrote, "To set forth the whole family of the Hawkeweedes in due forme and order is such a world of worke that I am in much doubt of mine own abilitie, it having lyen heavie on his shoudiers that hath already waded through them ... for such a multitude of varieties in forme pertaining to one herbe is not to be found againe in _rerum natura_ as I thinke," and the same idea, that the difficulty lay rather in man's imperfect powers of discrimination than in the nature of the materials to be discriminated, is reflected in many treatises early and late. It was however with the great ouburst of scientific activity which followed Linnaeus that the difficulty became acute. Simultaneously vast masses of new material were being collected from all parts of the world into the museums, and the products of the older countries were re-examined with a fresh zeal and on a scale of quantity previously unattempted. But the problem how to name the forms and where to draw lines, how much should be included under one name and where a new name was required, all this was felt, rather as a cataloguer's difficulty than as a physiological problem. And so we still hear on the one hand of the confusion caused by excessive "splitting" and subdivisions, and on the other of the uncritical "lumpers" who associate together under one name forms which another collector or observer would like to see distinguished. In spite of Darwin's hopes, the acceptance of his views has led to no real improvement--scarcely indeed to any change at all in either the practice or aims of systematists. In a famous passage in the _Origin_ he confidently declares that when his interpretation is generally adopted "Systematists will be able to pursue their labours as at present; but they will not be incessantly haunted by the shadowy doubt whether this or that form be a true species. This, I feel sure, and I speak after experience, will be no slight relief. The endless disputes whether or not some fifty species of British brambles are good species will cease." Those disputes nevertheless proceed almost exactly as before. It is true that biologists in general do not, as formerly, participate in these discussions because they have abandoned systematics altogether; but those who are engaged in the actual work of naming and cataloguing animals and plants usually debate the old questions in the old way. There is still the same divergence of opinion and of practice, some inclining to make much of small differences, others to neglect them. Not only does the work of the systematists as a whole proceed as if Darwin had never written but their attitude towards these problems is but little changed. In support of this statement I may refer to several British Museum Catalogues, much of the _Biologia Centrali-Americana_, Ridgway's _Birds of North America_, the _Fauna Hawaiensis_, indeed to almost any of the most important systematic publications of England, America, or any other country. These works are compiled by the most proficient systematists of all countries in the several groups, but with rare exceptions they show little misgiving as to the fundamental reality of specific differences. That the systematists consider the species-unit as of primary importance is shown by the fact that the whole business of collection and distribution of specimens is arranged with regard to it. Almost always the collections are arranged in such a way that the phenomena of variation are masked. Forms intermediate between two species are, if possible, sorted into separate boxes under a third specific name. If a species is liable to be constantly associated with a mutational form, the mutants are picked out, regardless of the circumstances of their origin, from the samples among which they were captured, and put apart under a special name. Only by a minute study of the original labels of the specimens and by redistributing them according to locality and dates, can their natural relations be traced. The published accounts of these collections often take no notice of variations, others make them the subject of casual reference. Very few indeed treat them as of much importance. From such indications it is surely evident that the systematists attach to the conception of species a significance altogether different from that which Darwin contemplated. I am well aware that some very eminent systematists regard the whole problem as solved. They hold as Darwin did that specific diversity has no physiological foundation or causation apart from fitness, and that species are impermanent groups, the delimitations of which are ultimately determined by environmental exigency or "fitness." The specific diversity of living things is thus regarded as being something quite different in nature from the specific diversity of inorganic substances. In practice those who share these opinions are, as might be anticipated, to be found among the 'lumpers' rather than among the 'splitters.' In their work, certainly, the Darwinian theory is actually followed as a guiding principle; unanalysed inter-gradations of all kinds are accepted as impugning the integrity of species; the underlying physiological problem is forgotten, and while the product is almost valueless as a contribution to biological research, I can scarcely suppose that it aids greatly in the advances of other branches of our science. But why is it that, with these exceptions, the consequences of the admittedly general acceptance of a theory of evolution are so little reflected in the systematic treatment of living things? Surely the reason is that though the systematist may be convinced of the general truth of the evolution theory at large, he is still of opinion that species are really distinct things. For him there are still 'good' species and 'bad' species and his experience tells him that the distinction between the two is not simply a question of degree or a matter of opinion. To some it may seem that this is mere perversity, a refusal to see obvious truth, a manifestation of the spirit of the collector rather than of the naturalist. But while recognising that from a magnification of the conception of species the systematists are occasionally led into absurdity I do not think the grounds for their belief have in recent times been examined with the consideration they deserve. The phenomenon of specific diversity is manifested to a similar degree by living things belonging to all the great groups, from the highest to the lowest, Vertebrates, Invertebrates, Protozoa, Vascular Plants, Algae, and Bacteria, all present diversities of such a kind that among them the existence of specific differences can on the whole be recognised with a similar degree of success and with very similar limitations. In all these groups there are many species quite definite and unmistakable, and others practically indefinite. The universal presence of specificity, as we may call it, similarly limited and characterised, is one of its most remarkable features. Not only is this specificity thus universally present among the different forms of life, but it manifests itself in respect of the most diverse characteristics which living things display. Species may thus be distinguished by peculiarities of form, of number, of geometrical arrangement, of chemical constitution and properties, of sexual differentiation, of development, and of many other properties. In any one or in several of these features together, species may be found distinguished from other species. It is also to be observed that the definiteness of these distinctions has no essential dependence on the nature of the characteristic which manifests them. It is for example sometimes said that colour-distinctions are of small systematic importance, but every systematist is familiar with examples (like that of the wild species of _Gallus_) in which colours though complex, show very little variation. On the other hand features of structure, sexual differentiation, and other attributes which by our standards are estimated as essential, may be declared to show much variation or little, not according to any principle which can be detected, but simply as the attention happens to be applied to one species or group of species, or to another. In many groups of animals and plants observers have hit upon characters which were for a time thought to be finally diagnostic of species. The Lepidoptera and Diptera for instance, have been re-classified according to their neuration. Through a considerable range of forms determinations may be easily made on these characters, but as is now well known, neuration is no more immune from variation than any other feature of organisation, and in some species great variability is the rule. Again it was once believed by some that the genitalia of the Lepidoptera provided a basis of final determination--with a similar sequel. In some groups, for example the Lycaenidae, or the Hesperidae, there are forms almost or quite indistinguishable on external examination, but a glance at the genitalia suffices to distinguish numerous species, while on the contrary among Pieridae a great range of species show scarcely any difference in these respects: and again in occasional species the genitalia show very considerable variations. The proposition that animals and plants are on the whole divisible into definite and recognisable species is an approximation to the truth. Such a statement is readily defensible, whereas to assert the contrary would be palpably absurd. For example, a very competent authority lately wrote: "In the whole Lepidopterous fauna of England there is no species of really uncertain limits."[7] Others may be disposed to make certain reservations, but such exceptions would be so few as scarcely to impair the validity of the general statement. The declaration might be extended to other orders and other lands. We know, of course, that the phenomenon of specific diversity is complicated by local differentiation: that, in general, forms which cannot disperse themselves freely exhibit a multitude of local races, and that of these some are obviously adaptative, and that a few even owe their peculiarity to direct environmental effects. Every systematist also is perfectly aware that in dealing with collections from little explored countries the occurrence of polymorphism or even of sporadic variation may make the practical business of distinguishing the species difficult and perhaps for the time impossible; still, conceding that a great part of the diversity is due to geographical differentiation, and that some is sporadic variation, our experience of our own floras and faunas encourages the belief that if we were thoroughly familiar with these exotic productions it would usually be possible to assign their specific limitations with an approach to certainty. For apart from any question of the justice of these wider inferences, if we examine the phenomenon of specificity as it appears in those examples which are nearest to hand, surely we find signs in plenty that specific distinction is no mere consequence of Natural Selection. The strength of this proposition has lain mainly in the appeal to ignorance. Steadily with the growth of knowledge has its cogency diminished, and such a belief could only have been formulated at a time when the facts of variation were unknown. In Darwin's time no serious attempt had been made to examine the manifestations of variability. A vast assemblage of miscellaneous facts could formerly be adduced as seemingly comparable illustrations of the phenomenon "Variation." Time has shown this mass of evidence to be capable of analysis. When first promulgated it produced the impression that variability was a phenomenon generally distributed amongst living things in such a way that the specific divisions must be arbitrary. When this variability is sorted out, and is seen to be in part a result of hybridisation, in part a consequence of the persistence of hybrids by parthenogenetic reproduction, a polymorphism due to the continued presence of individuals representing various combinations of Mendelian allelomorphs, partly also the transient effect of alteration in external circumstances, we see how cautious we must be in drawing inferences as to the indefiniteness of specific limits from a bare knowledge that intermediates exist. Conversely, from the accident of collocation or from a misleading resemblance in features we deem essential, forms genetically distinct are often confounded together, and thus the divergence of such forms in their other features, which we declare to be non-essential, passes as an example of variation. Lastly, and this is perhaps the most fertile of all the sources of confusion, the impression of the indefiniteness of species is created by the existence of numerous local forms, isolated geographically from each other, forms whose differences may be referable to any one of the categories I have enumerated. The advance has been from many sides. Something has come from the work of systematists, something from cultural experiments, something from the direct study of variation as it appears in nature, but progress is especially due to experimental investigation of heredity. From all these lines of inquiry we get the same answer; that what the naturalists of fifty years ago regarded as variation is not one phenomenon but many, and that what they would have adduced as evidence against the definiteness of species may not in fact be capable of this construction at all. If we may once more introduce a physical analogy, the distinctions with which the systematic naturalist is concerned in the study of living things are as multifarious as those by which chemists were confronted in the early days of their science. Diversities due to mechanical mixtures, to allotropy, to differences of temperature and pressure, or to degree of hydration, had all to be severally distinguished before the essential diversity due to variety of chemical constitution stood out clearly, and I surmise that not till a stricter analysis of the diversities of animals and plants has been made on a comprehensive scale, shall we be in a position to declare with any confidence whether there is or is not a natural and physiological distinction between species and variety. As I have said above, it is in the cases nearest to hand that the problem may be most effectively studied. Comparison between forms from dissimilar situations contributes something; but it is by a close examination of the behaviour, especially the genetic behaviour, of familiar species when living in the presence of their nearest allies that the most direct light on the problem is to be obtained. I cannot understand the attitude of those who, contemplating such facts as this examination elicits, can complacently declare that specific difference is a mere question of degree. With the spread of evolutionary ideas to speak much of the fixity of species has become unfashionable, and yet how striking and inscrutable are the manifestations of that fixity! Consider the group of species composing the _agrestis_ section of the genus _Veronica_, namely _Tournefortii_, _agrestis_, and _polita_. These three grow side by side in my garden, as they do in suitable situations over a vast area of the temperate regions. I have for years noticed them with some care and become familiar with their distinctions and resemblances. Never is there any real doubt as to the identity of any plant. The species show some variability, but I have never seen one which assumed any of the distinguishing features of the others. A glance at the fruits decides at once to which species a plant belongs. I find it impossible to believe that the fixity of these distinctions is directly dependent on their value as aids in the struggle for existence. The mode of existence of the three forms in so far as we can tell is closely similar. By whatever standard we reckon systematic affinity I suppose we shall agree that these species come very near indeed to each other. Bentham even takes the view that _polita_ is a mere variety of _agrestis_. Now in such cases as this it has been argued that the specific features of the several types have been separately developed in as many distinct localities, and that their present association is due to subsequent redistribution. Of these Veronicas indeed we know that one, _Tournefortii_ (= _Buxbaumii_) is as a matter of fact a recent introduction from the east.[8] But this course of argument leads to still further difficulties. For if it is true that the peculiarities of the several species have been perfected and preserved on account of their survival-value to their possessors, it follows that there must be many ways of attaining the same result. But since sufficient adaptation may be ensured in so many ways, the disappearance of the common parent of these forms is difficult to understand. Obviously it must have been a plant very similar in general construction to its modern representatives. Like them it must have been an annual weed, with an organisation conformable to that mode of life. Why then, after having been duly perfected for that existence should it have been entirely superseded in favour of a number of other distinct contrivances for doing the same thing, and--if a gradual transition be predicated--not only by them, but by each intermediate stage between them and the original progenitor? Surely the obvious inference from such facts is that the burden cast upon the theory of gradual selection is far greater than it can bear; that adaptation is not in practice a very close fit, and that the distinctions between these several species of Veronica have not arisen on account of their survival-value but rather because none of their diversities was so damaging as to lead to the extermination of its possessor. When we see these various Veronicas each rigidly reproducing its parental type, all comfortably surviving in competition with each other, are we not forced to the conclusion that _tolerance_ has as much to do with the diversity of species as the stringency of Selection? Certainly these species owe their continued existence to the fact that they are each good enough to live, but how shall we refer the distinctions between them directly or indirectly to the determination of Natural Selection? The control of Selection is loose while the conformity to specific distinction is often very strict and precise, and no less so even when several closely related species co-exist in the same area and in the same circumstances. The theory of Selection fails at exactly the point where it was devised to help: _Specific_ distinction. Let us examine a somewhat different set of facts in the case of another pair of nearly allied species _Lychnis diurna_ and _vespertina_. The two plants have much in common. Both are dioecious perennials, with somewhat similar flowers, the one crimson, the other white. Each however has its peculiarities which are discernible in almost any part of its structure, whether flower, leaf, fruit or seed, distinctions which would enable a person thoroughly familiar with the plants to determine at once from which species even a small piece had been taken. There is so much resemblance however as readily to support the surmise that the two were mere varieties of one species. Bentham, following Linnaeus, in fact actually makes this suggestion, with what propriety we will afterwards consider. Now this case is typical of many. The two forms have a wide distribution, occurring sometimes separately, sometimes in juxtaposition. _L. diurna_ is a plant of hedgerows and sheltered situations. _L. vespertina_ is common in fields and open spaces, where _diurna_ is hardly ever found; but not rarely _vespertina_ occurs in association with _diurna_ in the places which that plant frequents. In this case I do not doubt that we have to do with organisms of somewhat different aptitudes. That _L. vespertina_ has powers which _diurna_ has not is shown very clearly by the fact that _diurna_ is sometimes entirely absent from areas where _vespertina_ can abound.[9] But in order to understand the true genetic relations of the two plants to each other it is necessary to observe their behaviour when they meet as they not unfrequently do. If the _Lychnis_ population of such a locality be examined it will be found to consist of many undoubted and unmodified _diurna_, a number--sometimes few, sometimes many--of similarly unmodified _vespertina_, and an uncertain but usually rather small proportion of plants obviously hybrids between the two. How is it possible to reconcile these facts with the view that specific distinction has no natural basis apart from environmental exigency? Darwinian orthodoxy suggests that by a gradual process of Natural Selection either one of these two types was evolved from the other, or both from a third type. I cannot imagine that anyone familiar with the facts would propose the first hypothesis in the case of _Lychnis_, nor can I conceive of any process, whether gradual or sudden, by which _diurna_ could have come out of _vespertina_, or _vespertina_ out of _diurna_. Both however may no doubt have been derived from some original third type. It is conceivable that _Lychnis macrocarpa_ of Boissier, a native of Southern Spain and Morocco, may be this original form. This species is said to combine a white flower (like that of _L. vespertina_), with capsule-teeth rolled back (like those of _diurna_).[10] But whatever the common progenitor may have been, if we are to believe that these two species have been evolved from it by a gradual process of Natural Selection based on adaptation, enormous assumptions must be made regarding the special fitness of these two forms and the special unfitness of the common parent, and these assumptions must be specially invoked and repeated for each several feature of structure or habits distinguishing the three forms. Why, if the common parent was strong enough to live to give rise to these two species, is it either altogether lost now, or at least absent from the whole of Northern Europe? Its two putative descendants, though so distinct from each other, are, as we have seen, able often to occupy the same ground. If they were gradually derived from a common progenitor--necessarily very like themselves--can we believe that this original form should always, in all the diversities of soil and situation which they inhabit, be unable to exist? Some one may fancy that the hybrids which are found in the situations occupied by both forms are this original parental species. But nothing can be more certain than that these plants are simply heterozygous combinations made by the union of gametes bearing the characters of _diurna_ and _vespertina_.[11] For they may be reproduced exactly in F_{1} or in later generations of that cross when it is artificially made; when bred from their families exhibit palpable phenomena of segregation more or less complex; and usually, if perhaps not always, they are partially sterile.[12] In a locality on the Norfolk coast that I know well, there is a strip of rough ground chiefly sand-bank, which runs along the shore. This ground is full of _vespertina_. Not a hundred yards inland is a lane containing _diurna_, and among the _vespertina_ on the sand-bank are always some of the hybrid form, doubtless the result of fertilisation from the neighbouring _diurna_ population. Seed saved from these hybrids gave _vespertina_ and hybrids again, having obviously been fertilised by other _vespertina_ or by other hybrids, and I have no doubt that such hybrid plants if fertilised by _diurna_ would have shown some _diurna_ offspring. The absence of _diurna_ in such localities may fairly be construed as an indication that _diurna_ is there at a real disadvantage in the competition for life. But if, admitting this, we proceed to consider how the special aptitude of _vespertina_ is constituted, or what it is that puts _diurna_ at a disadvantage, we find ourselves quite unable to show the slightest connexion between the success of one or the failure of the other on the one hand, and _the specific characteristics_ which distinguish the two forms on the other. The orthodox Selectionist would, as usual, appeal to ignorance. We ask what can _vespertina_ gain by its white flowers, its more lanceolate leaves, its grey seeds, its almost erect capsule-teeth, its longer fruits, which _diurna_ loses by reason of its red flowers, more ovate leaves, dark seeds, capsule-teeth rolled back, and shorter fruits? We are told that each of these things _may_ affect the viability of their possessors. We cannot assert that this is untrue, but we should like to have evidence that it is true. The same problem confronts us in thousands upon thousands of examples, and as time goes on we begin to feel that speculative appeals to ignorance, though dialectically admissible, provide an insufficient basis for a proposition which, if granted, is to become the foundation of a vast scheme of positive construction. One thing must be abundantly clear to all, that to treat two forms so profoundly different as one, because intermediates of unknown nature can be shown to exist between them, is a mere shirking of the difficulties, and this course indeed creates artificial obstacles in the way of those who are seeking to discover the origin of organic diversity. In the enthusiasm with which evolutionary ideas were received the specificity of living things was almost forgotten. The exactitude with which the members of a species so often conform in the diagnostic, specific features passed out of account; and the scientific world by dwelling with a constant emphasis on the fact of variability, persuaded itself readily that species had after all been a mere figment of the human mind. Without presuming to declare what future research only can reveal, I anticipate that, when variation has been properly examined and the several kinds of variability have been successfully distinguished according to their respective natures, the result will render the natural definiteness of species increasingly apparent. Formerly in such a case as that of the two _Lychnis_ species, the series of "intermediates" was taken to be a palpable proof that _vespertina_ "graded" to _diurna_. It is this fact, doubtless, upon which Bentham would have relied in suggesting that both may be one species.[13] Genetic tests, though as yet imperfectly applied, make it almost certain that these inter-grading forms are not in any true sense variations from either species in the direction of the other, but combinations of elements derived from both. The points in which very closely allied species are distinguished from each other may be found in the most diverse features of their organisation. Sometimes specific difference is to be seen in a character which we can believe to be important in the struggle, but at least as often it is some little detail that we cannot but regard as trivial which suffices to differentiate the two species. Even when the diagnostic point is of such a nature that we can imagine it to make a serious difference in the economy we are absolutely at a loss to suggest why this feature should be a necessity to species A and unnecessary to species B its nearest ally. The house sparrow (_Passer domesticus_) is in general structure very like the tree sparrow (_P. montanus_). They differ in small points of colour. For instance _montanus_ has a black patch on the cheek which is absent in _domesticus_. The presence in the one species and the absence in the other are equally definite, and in both cases we are equally unable to suggest any consideration of utility in relation to these features. The two species are distinguished also by a characteristic that may well be supposed to be of great significance. In _domesticus_ the two sexes are strongly differentiated, the cock being more ornate than the hen. On the other hand the two sexes in _montanus_ are alike, and, if we take a standard from _domesticus_, we may fairly say that in _montanus_ the hen has the colouration of the male. It is not unreasonable to suppose that such a distinction may betoken some great difference in physiological economy, but the economical significance of this perhaps important distinction is just as unaccountable as that of the seemingly trivial but equally diagnostic colour-point. I have spoken of the fixed characteristics of the two species. If we turn to a very different feature, their respective liability to albinistic variation, we find ourselves in precisely similar difficulty. _Passer domesticus_ is a species in which individuals more or less pied occur with especial frequency, but in _P. montanus_ such variation is extremely rare if it occurs at all. The writer of the section on Birds in the _Royal Natural History_ (III., 1894-5, p. 393) calls attention to this fact and remarks that in that species he knows no such instance. The two species therefore, apart from any differences that we can suppose to be related to their respective habits, are characterised by small fixed distinctions in colour-markings, by a striking difference in secondary sexual characters, and by a difference in variability. In all these respects we can form no surmise as to any economic reason why the one species should be differentiated in the one way and the other in the other way, and I believe it is mere self-deception which suggests the hope that with fuller knowledge reasons of this nature would be discovered. The two common British wasps, _Vespa vulgaris_ and _Vespa germanica_, are another pair of species closely allied although sharply distinguished, which suggest similar reflexions. Both usually make subterranean nests but of somewhat different materials. _V. vulgaris_ uses rotten wood from which the nest derives a characteristic yellow colour, while _V. germanica_ scrapes off the weathered surfaces of palings and other exposed timber, material which is converted into the grey walls of the nest. The stalk by which the nest is suspended (usually to a root) in the case of _germanica_ passes freely through a hole in the external envelope, but _vulgaris_ unites this external wall solidly to the stalk. In bodily appearance and structure the two species are so much alike that they have often been confounded even by naturalists, and to the untrained observer they are quite indistinguishable. There are nevertheless small points of difference which almost though not quite always suffice to distinguish the two forms. For example the yellow part of the sinus of the eyes is emarginate in _vulgaris_ but not emarginate in _germanica_. _V. vulgaris_ often has black spots on the tibiae while in _germanica_ the tibiae are usually plain yellow. In both species there is a horizontal yellow stripe on the thorax, but whereas in _vulgaris_ this is a plain narrow stripe, it is in _germanica_ enlarged downwards in the middle. These and other apparently trivial details of colouration, though not absolutely constant, are yet so nearly constant that irregularities in these respects are quite exceptional. Lastly the genitalia of the males, though not very different, present small structural points of distinction which are enough to distinguish the two species at a glance.[14] In considering the meaning of the distinctions between these two wasps we meet the old problem illustrated by the Sparrows. The two species have somewhat different habits of life and we should readily expect to find differences of bodily organisation corresponding with the differences of habits. But is that what we do find? Surely not. To suppose that there is a correspondence between the little points of colour and structure which we see and the respective modes of life of the two species is perfectly gratuitous. We have no inkling of the nature of such a correspondence, how it can be constituted, or in what it may consist. Is it not time to abandon these fanciful expectations which are never realised? Everywhere both among animals and plants does the problem of specific difference reiterate itself in the same form. In view of such facts as I have related and might indefinitely multiply, the fixity of specific characters cannot readily be held to be a measure of their economic importance to their possessors. The incidence of specific fixity is arbitrary and capricious, sometimes lighting on a feature or a property which can be supposed to matter much, but as often is it attached to the most trifling of superficial peculiarities. The incidence of _variability_ is no less paradoxical, and without investigation of the particular case no one can say what will be found to show much or little variability. The very characteristic which in one species may exhibit extreme variability may in an allied species show extreme constancy. Illustrations will occur to any naturalist, but nowhere is this truth more strikingly presented than in the British Noctuid Moths. Many are so variable that, in the common phrase, "scarcely two can be found alike," while others show comparatively slight variation. It need scarcely be remarked that, in the instances I have in mind, the evidence of great variability is in no way due to the abundance with which the particular species occurs, for common species may show constancy, and less abundant species may show great variability. The polymorphism seems to be now at least a general property of the variable species, as the fixity is a property of the fixed species. In illustration I may refer to the following examples. _Dianthoecia capsincola_ is a common and widely distributed moth which feeds on _Lychnis_. It shows little variation. _Dianthoecia carpophaga_ is another species which feeds chiefly on _Silene_. Its habits are very similar to those of _capsincola_. Like that species it has a wide geographical range and is abundant in its localities, but in contrast to the fixity of _capsincola_, _carpophaga_ exhibits a complex series of varieties. _Agrotis suffusa_ (= _ypsilon_) is a moth widely spread through the southern half of England. It is very constant in colour and markings. _Agrotis segetum_ and _tritici_ are excessively variable both in ground colour and markings, being found in an immense profusion of dissimilar forms throughout their distribution. Of these and several other species of _Agrotis_ there are many named varieties, some of which have by various writers been regarded as specifically distinct. Of the genus _Noctua_ many species (e. g. _festiva_) show a similar polymorphism, but _N. triangulum_, though showing some variation in certain respects, is usually very constant to its type, and the same is true of _N. umbrosa_. In several species of _Taeniocampa_, especially _instabilis_, the multiplicity of forms is extreme, while _cruda_ (= _pulverulenta_) is a comparatively constant species. The genus _Plusia_ contains a number of constant species, but in _Plusia interrogationis_ we meet the fact that the central silvery mark undergoes endless variation. "Truly no two are alike," says Mr. Tutt, "and to look down a long series of _interrogationis_ is something like looking at a series of Chinese characters." In contrast to this we have the fact that in _Plusia gamma_ the very similar silvery mark is by no means variable. I have taken this series of cases from the Noctuid moths, but it would be as easy to illustrate the same proposition from the Geometridae or the Micro-Lepidoptera.[15] I have a long series of _Peronea cristana_, for example, which was given to me by Mr. W. H. B. Fletcher, of Bognor. All were beaten out of the same hedge, and their polymorphism is such that no one unaccustomed to such examples could suppose that they belonged to a single species. Another common form, _P. schalleriana_, which lives in similar circumstances, exhibits comparatively slight variability. It should be expressly noted that the variation of which I am speaking is a genuine polymorphism. Several of the species enumerated exhibit also geographical variation, possessing definite and often strikingly distinct races peculiar to certain localities; but apart from the existence of such local differentiation, stands out the fact upon which I would lay stress, that some species are excessively variable while others are by comparison constant, in circumstances that we may fairly regard as comparable. This fact is difficult to reconcile with the conventional view that specific type is directly determined by Natural Selection and that the precision with which a species conforms to its pattern is an indication of the closeness of that control. Anyone familiar with the characteristics of Moths will agree that the Noctuids, Geometrids and Tortricids are creatures whose existence depends in some degree on the success with which they can escape detection by their enemies in the imaginal state. We are therefore not surprised to find that some species of these orders exhibit definite geographical variation in conformity with the character of the ground, which may reasonably be supposed to aid in their protection. If this were all, there would be nothing to cause surprise. We might even be disposed to allow that variability might contribute to the perpetuation of animals so situated, on the principle that among a variety of surroundings some would probably be in harmony with the objects on which they rest. But we cannot admit the plausibility of an argument which demands on the one hand that the extreme precision with which species A adheres in the minutest details of its colour and pattern to a certain type shall be ascribed to the protective fitness of those details, and on the other hand that the abundant variability of species B shall be ascribed to the same determination. If it is absolutely necessary for A to conform to one type how comes it that B may range through some twenty distinct forms, any two of which differ more from each other than the regular species of many other genera? The only reply I can conceive is a suggestion that there _may_ be some circumstance which differentiates the various classes of cases, that the exigencies of the fixed species _may_ be different from those of the variable. Those who make such appeals to ignorance do not always perhaps realise whither this course of reasoning may lead. If admissible here the same argument would lead us to suggest that because albino moles have for an indefinite period occurred on a certain land near Bath there may be something in the soil or in the conditions of life near Bath which requires a proportion of albinos in its mole population. Or again, because the butterfly _Thais rumina_ in one locality, Digne in the south of France, has a percentage of individuals of the variety _Honoratii_ (with certain normally yellow spots on the hind wing coloured bright red) and nowhere else throughout its distribution, that therefore we may suggest that there is some difference in the condition of life at Digne which makes the continuance of _Honoratii_ there possible and beneficial. A polymorphism offering a parallel to that of the variable moths is afforded by the breeding plumage of the Ruff, the male of _Machetes pugnax_. The variety of plumage which these cocks exhibit is such that the statement that no two can be found alike is only a venial exaggeration. Newton remarks[16] "that all this wonderful 'show' is the consequence of the polygamous habit of the Ruff can scarcely be doubtful"; but even if it be conceded that the great external differentiation of the cocks may be a result of sexual selection, the problem of their _polymorphism_ remains unsolved, for, as we are well aware, polygamy is not usually associated with polymorphism of the male. The Black Cock (_Tetrao tetrix_), for example, is as polygamous as the Ruff, but in that and countless other cases, both sexes are constant to one type of plumage. When we thus compare the polymorphism of one species with the fixity of another, and attempt to determine the causes which have led to these extraordinary contrasts, two distinct lines of argument are open to us. We may ascribe the difference either to causes external to the organisms, primarily, that is to say, to a difference in the exigencies of Adaptation under Natural Selection; or on the other hand we may conceive the difference as due to innate distinctions in the chemical and physiological constitutions of the fixed and the variable respectively. There is truth undoubtedly in both conceptions. If the mole were physiologically incapable of producing an albino that variety would not have come into being, and if the albino were totally incapable of getting its living it would not be able to hold its own. Were _Plotheia frontalis_ constructed on a chemical plan which admitted of no variation, the countless varieties would not have been produced; and if one of its varieties had an overwhelming success out of all proportion to that of the rest, then the species would soon become monomorphic again. We cannot declare that Natural Selection has no part in the determination of fixity or variability; nevertheless looking at the whole mass of fact which a study of the incidence of variation provides, I incline to the view that the variability of polymorphic forms should be regarded rather as a thing tolerated than as an element contributing directly to their chances of life; and on the other hand that the fixity of the monomorphic forms should be looked upon not so much as a proof that Natural Selection controls them with a greater stringency, but rather as evidence of a natural and intrinsic stability of chemical constitution. Compare the condition of a variable form like the male Ruff (or in a less degree the Red Grouse in both its sexes) with that of the common Pheasant which is comparatively constant. In the Pheasant no doubt variations do occur as in other wild birds, but apart from the effects of mongrelisation the species is unquestionably uniform. Could it seriously be proposed that we should regard the constancy of the pheasant's plumage in this country as depending on the special fitness of that type of colouration? Even if the pheasant be not an alien in Western Europe, it has certainly been protected for centuries, and for a considerable period has existed in a state of semi-domestication. Such conditions should give good opportunity for polymorphism to be produced. In some coverts various aberrations do of course occur and persist, yet there is nothing indicative of a general relaxation of the fixity of the specific type, and the pheasant remains substantially a fixed species.[17] The common pheasant (_Phasianus colchicus_) even shows little of that disposition to form local races which appears in the species of Further India. Are we not then on safer ground in regarding the fixity of our species as a property inherent in its own nature and constitution? Just as in ages of domestication no rose has ever given off a blue variety so has the pheasant never broken out into the polymorphism of the Ruff. As soon as it is realised how largely the phenomena of variation and stability must be an index of the internal constitution of organisms, and not mere consequences of their relations to the outer world, such phenomena acquire a new and more profound significance. FOOTNOTES: [1] In _Mendel's Principles of Heredity_ (Cambridge University Press, 1909) I have dealt with this subject, giving an account of the principal facts discovered up to the beginning of 1909. [2] Matthioli Opera, Ed. 1598, p. 8, originally published 1565. [3] Ray's instances relate to Kales, and in most of these examples we can see that there was no question of mutation or transmutation at all, but that the occurrence was due either to mistake or to cross-fertilisation. Sharrock, to whom Ray refers, was inclined to discredit stories of transmutation, but he has also this passage (_History of the Propagation and Improvement of Vegetables by the Concurrence of Art and Nature_, Oxford, 1660, p. 29): "It is indeed growen to be a great question, whether the transmutation of a species be possible either in the vegetable, Animal, or Minerall Kingdome. For the possibility of it in the vegetable; I have heard _Mr. Bobart_ and his _Son_ often report it, and proffer to make oath that the Crocus and Gladiolus, as likewise the Leucoium, and Hyacinths by a long standing without replanting have in his garden changed from one kind to the other: and for satisfaction about the curiosity in the presence of _Mr. Boyle_ I tooke up some bulbs of the very numericall roots whereof the relation was made, though the alteration was perfected before, where we saw the diverse bulbs growing as it were on the same stoole, close together, but no bulb half of the one kind, and the other half of the other: But the changetime being past it was reason we should believe the report of good artists in matters of their own faculty." Robert Sharrock was a fellow of New College, Oxford. Both the Bobarts were professional botanists, the father was author of a Catalogue of the plants in the Hortus Medicus at Oxford, and the son was afterwards Curator of the Oxford Garden. [4] _Mém. Ac. roy. des Sci._ for 1719 (1721), p. 59. [5] _Amoen. Acad._, 1789, vol. 6. I do not know whether attention has been called to the curious mistake which Linnaeus makes in the course of this argument. He cites the differences between the Mule and the Hinny in illustration of his thesis, pointing out that the Mule is externally more like a horse and the Hinny more like an ass. This, he says, is because the Mule has the horse for a father, and the Hinny the ass, thus inverting the actual facts! [6] _Proc. Washington Ac. Sci._, 1909, XI, pp. 17-26. [7] J. W. Tutt, in _Ent. Rec._, 1909, XXI, p. 185. [8] E. Lehmann (_Bull. l'Herb. Boissier_, Ser. 2, VIII, 1908, p. 229) has published an admirable paper on the interrelationships of these species and has instituted cultural experiments which will probably much elucidate the nature of their specific distinctness. As regards the existence of intermediate forms he comes to the conclusion that two only can be so regarded. The first was described by Kuntze from specimens found on a flower-pot on board a Caspian steamer, from which Lehmann proposes the new specific name _Siaretensis_. This comes between _polita_ and _filiformis_, a close ally of _Tournefortii_. The other, which combines some of the features of both _polita_ and _Tournefortii_, was found in the province of Asterabad. [9] In Cambridgeshire for example _vespertina_ is common but _diurna_ is absent. Whether this absence is connected with the general presence of chalk I cannot say. When introduced artificially _diurna_ establishes itself, for a time at least, without any apparent difficulty and occasionally escapes from the garden on to the neighbouring roadside. [10] Conceivably however it may be a segregated combination. For an account of this plant see Boissier, _Voy. Bot. Midi de l'Espagne_, 1839, II, 722. [11] A discussion of this subject with references to literature is given by Rolfe, in an excellent paper on "Hybridisation viewed from the standpoint of Systematic Botany" (_Jour. R. Hort. Soc._, XXIV, 1900, p. 197). He concludes: "The simple fact is that the two plants (_L. diurna_ and _vespertina_) are thoroughly distinct in numerous particulars, and affect such different habitats that in some localities one or the other of them is completely wanting. But when their stations are adjacent they hybridise together very readily, and it is here that these intermediate forms occur which have puzzled botanists so much." The same paper contains valuable information concerning several cognate illustrations. [12] In only two cases have I seen such plants (both females) completely sterile. [13] As is well known, in an even more notorious example, he proposed to unite _Primula vulgaris_, _P. elatior_, and _P. acaulis_, similarly relying on the existence of "intermediates," which we now well know to be mongrels between the species. [14] For an account of the distinctions between _Vespa vulgaris_ and _germanica_ see Ch. Janet, _�tudes sur les Fourmis, les Guêpes et les Abeilles_, 11^e, Note. Sur _Vespa germanica_ et _V. vulgaris_. Limoges (Ducourtieux), 1895; and R. du Buysson, Monographie des Guêpes, _Ann. Soc. Ent. France_, 1903, Vol. LXXII, p. 603, Pl. VIII. [15] The statements made above are for the most part taken from Barrett, C. G., _Lepidoptera of the British Islands_, and from Tutt, J. W., _The British Noctuae and their Varieties_. The reader who is unfamiliar with the amazing polymorphism exhibited by some of these moths should if possible take an opportunity of looking over a long series in a collection, or, if that be impossible, refer to the admirable coloured plates published by Barrett. It may not be superfluous to observe that plenty of similar examples are known in other countries. For instance _Plotheia frontalis_, a Noctuid which often abounds in Ceylon, shows an equally bewildering wealth of forms. If a dozen specimens of such a species were to be brought home from some little known country, each individual would almost certainly be described as the type of a distinct species. (See the coloured plate published by Sir G. Hampson, Cat. Brit. Mus., Heterocera, Vol. IX.) [16] _Dict. of Birds_, p. 800. It would be interesting and profitable to attempt in a long series of Ruffs to determine the Mendelian factors which by their combinations give rise to this complex assemblage of varietal forms. A few such factors both of colour and pattern can be at once distinguished, and it is noticeable that some of the resulting types of barring, spangling and penciling show a perceptible correspondence with some of the types of colouration found in the breeds of domestic fowls. [17] Howard Saunders (_Illust. Manual of British Birds_, 1899, p. 499) states that there is evidence that the pheasant had become naturalized in the south of England before the Norman invasion. He adds, "little, if any, deviation from the typical _P. colchicus_ took place up to the end of last century, when the introduction of the Chinese Ring-necked _P. torquatus_ commenced, which has left almost indelible marks, especially with regard to the characteristic white collar." CHAPTER II MERISTIC PHENOMENA Twenty years ago in describing the facts of Variation, argument was necessary to show that these phenomena had a special value in the sciences of Zoology and Botany. This value is now universally understood and appreciated. In spite however of the general attention devoted to the study of Variation, and the accumulation of material bearing on the problem, no satisfactory or searching classification of the phenomena is possible. The reason for this failure is that a real classification must presuppose knowledge of the chemistry and physics of living things which at present is quite beyond our reach. It is however becoming probable that if more knowledge of the chemical and physical structure of organisms is to be attained, the clue will be found through Genetics, and thus that even in the uncoordinated accumulation of facts of Variation we are providing the means of analysis applicable not only to them, but to the problems of normality also. The only classification that we can yet institute with any confidence among the phenomena of Variation is that which distinguishes on the one hand variations in the processes of division from variations in the nature of the substances divided. Variations in the processes of division are most often made apparent by a change in the number of the parts, and are therefore called _Meristic_ Variations, while the changes in actual composition of material are spoken of as _Substantive_ Variations. The Meristic Variations form on the whole a natural and fairly well defined group, but the Substantive Variations are obviously a heterogeneous assemblage. Though this distinction does not go very far, it is useful, and in all probability fundamental. It is of value inasmuch as it brings into prominence the distinct and peculiar part which the process of division, or, more generally, repetition of parts, plays in the constitution of the forms of living things. That there may be a real independence between the Meristic and the Substantive phenomena is evident from the fact both that Meristic changes may occur without Substantive Variation, and that the substances composing an organism may change without any perceptible alteration in its meristic structure. When the distinction between these two classes of phenomena is perceived it will be realised that the study of genetics has on the one hand a physical, or perhaps more strictly a mechanical aspect, which relates to the manner in which material is divided and distributed; and also a chemical aspect, which relates to the constitution of the materials themselves. Somewhat as the philosophers of the seventeenth and eighteenth centuries were awaiting both a chemical and a mechanical discovery which should serve as a key to the problems of unorganised matter, so have biologists been awaiting two several clues. In Mendelian analysis we have now, it is true, something comparable with the clue of chemistry, but there is still little prospect of penetrating the obscurity which envelops the mechanical aspect of our phenomena. To make clear the application of the terms chemical and mechanical to the problem of Genetics the nature of that problem must be more fully described. In its most concrete form this problem is expressed in the question, how does a cell divide? If the organism is unicellular, and the single cell is the whole body, then the process of heredity is accomplished in the single operation of cell-division. Similarly in animals and plants whose bodies are made up of many cells, the whole process of heredity is accomplished in the cell-divisions by which the germ-cells are formed. When therefore we see a cell dividing, we are witnessing the process by which the form and the properties of the daughter-cells are determined. Now this process has the two aspects which I have called mechanical and chemical. The term "_Entwicklungsmechanik_" has familiarised us with the application of the word mechanics to these processes, but on reflexion it will be seen that this comprehensive term includes two sorts of events which are sometimes readily distinguishable. There is the event by which the cell _divides_, and the event by which the two halves or their descendants are or may be _differentiated_. It is common knowledge that in some cell-divisions two similar halves, indistinguishable in appearance, properties, and subsequent fate, may be produced, while in other divisions daughter-cells with distinct properties and powers are formed. We cannot imagine but that in the first case, when the resulting cells are identical, the division is a mechanical process by which the mother-cell is simply cut in two; while in order that two differentiated halves may be produced, some event must have taken place by which a chemical distinction between the two halves is effected.[1] In any ordinary Mendelian case we have a clear proof that such a chemical difference may be established between germ-cells. The facts of colour-inheritance for instance prove that germ-cells, otherwise identical, may be formed _possessing_ the chromogen-factor which is necessary to the formation of colour in the flowers, or _destitute_ of that factor. Similarly the germ-cells may possess the ferment which, by its action on the chromogenic substance, produces the colour, or they may be without that ferment. The same line of argument applied to a great range of cases. Nevertheless, though differences in chemical properties are often thus constituted by cell-divisions, and though we are thus able to make a quasi-chemical analysis of the individual by determining and enumerating these properties, yet it is evident that the distribution of these factors is not itself a chemical process. This is proved by the fact that similar divisions may be effected between halves which are exactly alike, and also by the fact that the numbers in which the various types of germ-cells are formed negative any suggestion of valency between them. The recognition of the unit-factors may lead--indeed must lead--to great advances in chemical physiology which without that clue would have been impossible, but in causation the chemical phenomena of heredity must be regarded as secondary to the physical or mechanical phenomena by which the cells and their constituents are divided and separated. When therefore we speak of the _essential_ phenomena of heredity we mean the mechanics of division, especially, though not, as we shall see, exclusively, of _cell_-division; and in the relation between the two halves of the dividing cell we have the problem presented in what seems to be its simplest form. In attempting to form some conception of the processes by which bodily characteristics are transmitted, or--to avoid that confusing metaphor of "transmission"--how it comes about that the offspring can grow to resemble its parent, continuity of the germ-substance which in some animals is a visible phenomenon,[2] gives at least apparent help. An egg for example on becoming adult develops in certain parts a particular pigment. The eggs of that adult when they reach the appropriate age develop the same pigment. We have no clear picture of the mechanism by which this process is effected, but when we realise that the pigment results from the interaction of certain substances, and that since all the eggs are in reality pieces of the same material, it seems, unless we inquire closely, not unnatural that the several pieces of the material should exhibit the same colours at the same periods of their development. The continuity of the material of the germs suggests that there is a continuity of the materials from which the pigment is formed, and that thus an actual bit of those substances passes into each egg ready at the appropriate moment to generate the pigment. The argument thus outlined applies to all _substantive_ characteristics. In each case we can imagine, if we will, the appearance of that characteristic as due to the contribution of its rudiment from the germ tissues. When we consider more critically it becomes evident that the aid given by this mental picture is of very doubtful reality, for even if it were true that any predestined particle actually corresponding with the pigment-forming materials is definitely passed on from germ to germ, yet the power of increase which must be attributed to it remains so incomprehensible that the mystery is hardly at all illuminated. When however we pass from the substantive to the meristic characters, the conception that the character depends on the possession by the germ of a particle of a specific material becomes even less plausible. Hardly by any effort of imagination can we see any way by which the division of the vertebral column into _x_ segments or into _y_ segments, or of a Medusa into 4 segments or into 6, can be determined by the possession or by the want of a material particle. The distinction must surely be of a different order. If we are to look for a physical analogy at all we should rather be led to suppose that these differences in segmental numbers corresponded with changes in the amplitude or number of dividing waves than with any change in the substance or material divided. PHENOMENA OF DIVISION I have said that in the division of a cell we seem to see the problem in its simplest form, but it is important to observe that the problem of division may be presented by the bodies of animals and plants in forms which are independent of the divisions between cells. The existence of pattern implies a repetition of parts, and repetition of parts when developed in a material originally homogeneous can only be created by division. Cell-division is probably only a special case of a process similar to that by which the pattern of the skeleton is laid down in a unicellular body such as that of a Radiolarian or Foraminiferan. Attempts have lately been made to apply mathematical treatment to problems of biology. It has sometimes seemed to me that it is in the geometrical phenomena of life that the most hopeful field for the introduction of mathematics will be found. If anyone will compare one of our animal patterns, say that of a zebra's hide, with patterns known to be of purely mechanical production, he will need no argument to convince him that there must be an essential similarity between the processes by which the two kinds of patterns were made and that parts at least of the analysis applicable to the mechanical patterns are applicable to the zebra stripes also. Patterns mechanically produced are of many and very diverse kinds. One of the most familiar examples, and one presenting some especially striking analogies to organic patterns, is that provided by the ripples of a mackerel sky, or those made in a flat sandy beach by the wind or the ebbing tide. With a little search we can find among the ripple-marks, and in other patterns produced by simple physical means, the closest parallels to all the phenomena of striping as we see them in our animals. The forking of the stripes, the differentiation of two "faces," the deflections round the limbs and so forth, which in the body we know to be phenomena of division, are common both to the mechanical and the animal patterns. We cannot tell what in the zebra corresponds to the wind or the flow of the current, but we can perceive that in the distribution of the pigments, that is to say, of the chromogen-substances or of the ferments which act upon them, a rhythmical disturbance has been set up which has produced the pattern we see; and I think we are entitled to the inference that in the formation of patterns in animals and plants mechanical forces are operating which ought to be, and will prove to be, capable of mathematical analysis. The comparison between the striping of a living organism and the sand-ripples will serve us yet a little farther, for a pattern may either be formed by actual cell-divisions, and the distribution of differentiation coincidently determined, or--as visibly in the pigmentation of many animal and plant tissues--the pattern may be laid down and the pigment (for example) distributed through a tissue across or independently of the cell-divisions of the tissue. Our tissues therefore are like a beach composed of sands of different kinds, and different kinds of sands may show distinct and interpenetrating ripples. When the essential analogy between these various classes of phenomena is perceived, no one will be astonished at, or reluctant to admit, the reality of discontinuity in Variation, and if we are as far as ever from knowing the actual causation of pattern we ought not to feel surprised that it may arise suddenly or be suddenly modified in descent. Biologists have felt it easier to conceive the evolution of a striped animal like a zebra from a self-coloured type like a horse (or of the self-coloured from the striped) as a process involving many intergradational steps; but so far as the _pattern_ is concerned, the change may have been decided by a single event, just as the multitudinous and ordered rippling of a beach may be created or obliterated at one tide. [Illustration: FIG. 1. Tusk of Indian elephant, showing an abnormal segmentation.] This point is well illustrated by the tusk of an Indian elephant which I lately found in a London sale-room. This tusk is by some unknown cause, presumably a chronic inflammation, thrown up into thirteen well-marked ridges which closely simulate a series of segments (Fig. 1). Whatever the cause the condition shows how easily a normally unsegmented structure may be converted into a series of repeated parts. The spread of segmentation through tissues normally unsegmented is very clearly exemplified in the skates' jaws shown in Fig. 2. The right side of the upper figure shows the normal arrangement in the species _Rhinoptera jussieui_, but the structure on the left side is very different. The probable relations of the several rows of teeth to the normal rows is indicated by the lettering, but it is evident that by the appearance of new planes of division constituting separate centers of growth, the series has been recast. The pattern of the left side is so definite that had the variation affected the right side also, no systematist would have hesitated to give the specimen a new specific name. The other two drawings show similar variations of a less extensive kind, the nature of which is explained by the lettering of the rows of teeth. [Illustration: FIG. 2. Jaws of Skates (_Rhinoptera_) showing meristic variation. (For a detailed discussion see _Materials for the Study of Variation_, p. 259.)] This power to divide is a fundamental attribute of life, and of that power cell-division is a special example. In regard to almost all the chief vital phenomena we can say with truth that science has made some progress. If I mention respiration, metabolism, digestion, each of these words calls to mind something more than a bare statement that such acts are performed by an animal or a plant. Each stands for volumes of successful experiment and research, But the expression cell-division, the fundamental act which typifies the rest, and on which they all depend, remains a bare name. We can see with the microscope the outward symptoms of division, but we have no surmise as to the nature of the process by which the division is begun or accomplished. I know nothing which to a man well trained in scientific knowledge and method brings so vivid a realisation of our ignorance of the nature of life as the mystery of cell-division. What is a living thing? The best answer in few words that I know is one which my old teacher, Michael Foster, used to give in his lectures introductory to biology. "A living thing is a vortex of chemical and molecular change." This description gives much, if not all, that is of the essence of life. The living thing is unlike ordinary matter in the fact that, through it, matter is always passing. Matter is essential to it; but, provided that the flow in and out is unimpeded, the life-process can go on so far as we know indefinitely. Yet the living "vortex" differs from all others in the fact that it can divide and throw off other "vortices," through which again matter continually swirls. We may perhaps take the parallel a stage further. A simple vortex, like a smoke-ring, if projected in a suitable way will twist and form two rings. If each loop as it is formed could grow and then twist again to form more loops, we should have a model representing several of the essential features of living things. It is this power of spontaneous division which most sharply distinguishes the living from the non-living. In the excellent book dealing with the problems of development, lately published by Mr. Jenkinson a special emphasis is very properly laid on the distinction between the processes of division, and those of differentiation. Too often in discussions of the developmental processes the distinction is obscured. He regards differentiation as the "central difficulty." "Growth and division of the nucleus and the cells," he tells us, are side-issues. This view is quite defensible, but I suspect that the division _is_ the central difficulty, and that if we could get a rationale of what is happening in cell-division we should not be long before we had a clue to the nature of differentiation. It may be self-deception, but I do not feel it impossible to form some hypothesis as to the mode of differentiation, but in no mood of freest speculation are we ever able to form a guess as to the nature of the division. We see differentiations occurring in the course of chemical action, in some phenomena of vibration and so forth: but where do we see anything like the spontaneous division of the living cell? Excite a gold-leaf electroscope, and the leaves separate, but we know that is because they were double before. In electrolysis various substances separate out at the positive and negative poles respectively. Now if in cell-division the two daughter-cells were always dissimilar--that is to say, if differentiation always occurred--we could conceive some rough comparison with such dissociations. But we know the dissimilarity between daughter-cells is not essential. In the reproduction of unicellular organisms and many other cases, the products formed at the two poles are, so far as we can tell, identical. Any assumption to the contrary, if we were disposed to make it, would involve us in difficulties still more serious. At any rate, therefore, if differentiation be really the central difficulty in development, it is division which is the essential problem of heredity. Sir George Darwin and Professor Jeans tell us that "gravitational instability" consequent on the condensation of gases is "the primary agent at work in the actual evolution of the universe," which has led to the division of the heavenly bodies. The greatest advance I can conceive in biology would be the discovery of the nature of the instability which leads to the continual division of the cell. When I look at a dividing cell I feel as an astronomer might do if he beheld the formation of a double star: that an original act of creation is taking place before me. Enigmatical as the phenomenon seems, I am not without hope that, if it were studied for its own sake, dissociated from the complications which obscure it when regarded as a mere incident in development, some hint as to the nature of division could be found. It is I fear a problem rather for the physicist than for the biologist. The sentiment may not be a popular one to utter before an assembly of biologists, but looking at the truth impersonally I suspect that when at length minds of first rate analytical power are attracted to biological problems, some advance will be made of the kind which we are awaiting. The study of the phenomena of bodily symmetry offers perhaps the most hopeful point of attack. The essential fact in reproduction is cell-division, and the essential basis of hereditary resemblance is the symmetry of cell-division. The phenomena of twinning provide a convincing demonstration that this is so. By twinning we mean the production of equivalent structures by division. The process is one which may affect the whole body of an animal or plant, or certain of its parts. The term twin as ordinarily used refers to the simultaneous birth of two individuals. Those who are naturalists know that such twins are of two kinds, (1) twins that are not more alike than any other two members of the same family, and (2) twins that are so much alike that even intimate friends mistake them. These latter twins, except in imaginative literature, are always of the same sex. It is scarcely necessary for me to repeat the evidence from which it has been concluded that without doubt such twins arise by division of the same fertilised ovum. There is a perfect series of gradations connecting them with the various forms of double monsters united by homologous parts. They have been shown several times to be enclosed in the same chorion, and the proofs of experimental embryology show that in several animals by the separation of the two first hemispheres of a dividing egg twins can be produced. Lastly we have recently had the extraordinarily interesting demonstration of Loeb, to which I may specially refer. Herbst some years ago found that in sea water, from which all lime salts had been removed, the segments of the living egg fall apart as they are formed. Using this method Loeb has shown that a temporary immersion in lime-free sea water may result in the production of 90 per cent. of twins. We are therefore safe in regarding the homologous or "identical" twins as resulting from the divisions of one fertilised egg, while the non-identical or "fraternal" twins, as they are called, arise by the fertilisation of two separate ova.[3] In the resemblance of identical twins we have an extreme case of hereditary likeness[4] and a proof, if any were needed, that the cause of individual variation is to be sought in the differentiation of germ-cells. The resemblance of identical twins depends on two circumstances, First, since only two germ-cells take part in their production, difference between the germ cells of the same individual cannot affect them. Secondly the division of the fertilised ovum, the process by which they became two instead of one, must have been a symmetrical division. The structure of twins raises however one extremely significant difficulty, which as yet we cannot in any way explain. The resemblance between twins is a phenomenon of symmetry, like the resemblance between the two sides of a bilaterally symmetrical body. Not only is the general resemblance readily so interpreted, but we know also that in double monsters, namely unseparated twins, various anatomical abnormalities shown by the one half-body are frequently shown by the other half-also.[5] The two belong to one system of symmetry. How then does it happen that the body of one of a pair of twins does not show a transposition of viscera? We know that the relation of right and left implies that the one should be the mirror-image of the other. Such a relation of images may be maintained even in minute details. For example if the same pattern of finger-print is given by the fingers of the two hands, one is the reverse of the other. In double monsters, namely unseparated twins, there is evidence that an inversion of viscera does occur with some frequency. Evidence from such cases is not so clear and simple as might be expected, because as a matter of fact, the heart and stomach, upon which the asymmetry of the viscera chiefly depend, are usually common to the two bodies. Duplicity generally affects either the anterior end alone, or the posterior end alone. The division is generally _from the heart forwards_, giving two heads and two pairs of anterior limbs on a common trunk, or _from the heart backwards_, giving two pairs of posterior limbs with the anterior body common. In either case, though the bodies may be grouped in a common system of symmetry, neither can be proved to show definite reversal of the parts. To see that reversal recourse must be had to more extreme duplications, such as the famous Siamese Twins. They, as a matter of fact, were an excellent instance of the proposition that twins are related as mirror-images, for both of them had eleven pairs of ribs instead of the normal twelve, and one of them had a partial reversal of viscera.[6] (Küchenmeister, _Verlagerung_, etc., p. 204.) If anyone could show how it is that neither of a pair of twins has transposition of viscera the whole mystery of division would, I expect, be greatly illuminated.[7] At present we have simply to accept the fact that twins, by virtue of their detachment from each other, have the power of resuming the polarity which is proper to any normal individual. It was nevertheless with great interest that I read Wilder's recent observation[8] that occasionally in identical twins the finger-print of one or both the index-fingers may be reversed, showing that there is after all some truth in the notion that reversal should occur in them. There is another phenomenon by twinning which, if we could understand it, might help. I refer to the free-martin, the subject of one of John Hunter's masterpieces of anatomical description. In horned cattle twin births are rare, and when twins of opposite sexes are born, the male is perfect and normal, but the reproductive organs of the female are deformed and sterile, being known as a free-martin. The same thing occasionally happens in sheep, suggesting that in sheep also twins may be formed by the division of one ovum; for it is impossible to suppose that mere development in juxtaposition can produce a change of this character. I mention the free-martin because it raises a question of absorbing interest. It is conceivable that we should interpret it by reference to the phenomenon of gynandromorphism, seen occasionally in insects, and also in birds as a great rarity. In the gynandromorph one side of the body is male, the other female. A bullfinch for instance has been described with a sharp line of division down the breast between the red feathers of the cock on one side and the brown feathers of the hen on the other. (Poll, H., _SB. Ges. Nat. Fr._, Berlin, 1909, p. 338.) In such cases neither side is sexually perfect. If the halves of such a gynandromorph came apart, perhaps one would be a free-martin. The behaviour of homologous twinning in heredity has been little studied. It does not exist as a normal feature in any animal which is amenable to experiment, and we cannot positively assert that a comparable phenomenon exists in plants; for in them--the Orange, for example--polyembryony may evidently be produced by a parthenogenetic development of nucellar tissue. It is possible that in Man twinning is due to a peculiarity of the mother, not of the father. It may and not rarely does descend from mother to daughter, but whether it can be passed on through a male generation to a daughter again, there is not sufficient evidence to show. The facts as far as they go are consistent with the inference which may be drawn from Loeb's experiment, that the twinning of a fertilized ovum may be determined not by the germ-cells which united to form it, but by the environment in which it begins to develop. The opinion that twinning may descend through the male directly has been lately expressed by Dr. J. Oliver in the _Eugenics Review_ (1912), on the evidence of cases in which twins had occurred among the relations of fathers of twins, but I do not know of any comprehensive collection of evidence bearing on the subject. Besides twinning of the whole body a comparable duplicity of various parts of the same body may occur. Such divisions affect especially those organs which have an axis of bilateral symmetry, such as the thumb, a cotyledon, a median petal, the frond of a fern or the anal fin of a fish. From the little yet known it is clear that the genetic analysis of these conditions must be very difficult, but evidence of any kind regarding them will be valuable. We want especially to know whether these divisions are due to the _addition_ of some factor or power which enables the part to divide, or whether the division results from the _absence_ of something which in the normal body prevents the part from dividing. Breeding experiments, so far as they go, suggest that the less divided state is usually dominant to the more divided.[9] The two-celled Tomato fruit is dominant to the many-celled type. The Manx Cat's tail, with its suppression of caudal segmentation is a partial dominant over the normal tail. The tail of the Fowl in what is called the "Rumpless" condition is at least superficially comparable with that of the Manx Cat, and though the evidence is not wholly consistent, Davenport obtained facts indicating that this suppressed condition of the caudal vertebrae is an imperfect dominant.[10] Some evidence may also be derived from other examples of differences which at first sight appear to be substantive though they are more probably meristic in ultimate nature. The distinction between the normal and the "Angora" hair of the Rabbit is a case in point. We can scarcely doubt that one of the essential differences between these two types is that in the Angora coat the hair-follicles are more finely divided than they are in the normal coat, and we know that the normal, or less-divided condition, is dominant to the Angora, or more finely divided. [Illustration: FIG. 3. _I_, _II_, _III_, various degrees of syndactyly affecting the medius and annularis in the hand; _IV_, syndactyly affecting the index and medius in the foot. (After Annandale.)] In the case of the solid-hoofed or "mule-footed" swine, the evidence shows, as Spillman has lately pointed out,[11] that the condition behaves as a dominant. The essential feature of this abnormality is that the digits III and IV are partially united. The union is greatest peripherally. Sometimes the third phalanges only are joined to form one bone, but the second and even the first phalanges may also be compounded together. Here the variation is obviously meristic and consists in a failure to divide, the normal separation of the median digits of the foot being suppressed. [Illustration: FIG. 4. Case of complete syndactyly in the foot. _II_ and _III_, digit apparently representing the index and medius. _c_^{2} + _c_^{3}, bone apparently representing the middle and external cuneiform; _cb_, cuboid; _c_^{1}, internal cuneiform. (After Gruber.)] Webbing between the digits, in at least some of its manifestations, is a variation of similar nature. The family recorded by Newsholme[12] very clearly shows the dominance of this condition. The case is morphologically of great interest and must undoubtedly have a bearing on the problems of the mechanics of Division. In discussing the phenomena of syndactylism I pointed out some years ago that the digits most frequently united in the human hand are III and IV, while in the foot, union most frequently takes place between II and III.[13] In Newsholme's family the union was always between II and III of the foot, except in the case of one male who had the digits III and IV of the right _hand_ alone webbed together. There can be little doubt that the geometrical system on which the foot is planned has an axis of symmetry passing between the digits II and III, while the corresponding axis in the hand passes between III and IV. Union between such digits may therefore be regarded as comparable with any non-division or "coalescence" of lateral structures in a middle line, and when as in these examples such a condition is shown to be a dominant we cannot avoid the inference that some concrete factor has the power of suppressing or inhibiting this division. Figs. 3 and 4 illustrate degrees of union between digits in the human hand and foot. It is not in question that various other forms of irregular webbing and coalescence of digits exist, and respecting the genetic behaviour of these practically nothing is as yet known. Such a case is described by Walker,[14] in which the first and second metacarpals of both feet were fused in mother and daughter, and several more are found in literature. Contrasted with these phenomena we have the curious fact that in the Pigeon, Staples-Browne found webbing of the toes a _recessive_ character. The question thus arises whether this webbing is of the same nature as that shown to be a dominant in Man, and indeed whether the phenomenon in pigeons is really meristic at all. There is some difference perceptible between the two conditions; for in Man there is not so much a development of a special web-like skin uniting the digits as a want of proper division between the digits themselves, and in extreme cases two digits may be represented by a single one. In the Pigeon I am not aware that a real union of this kind has ever been observed, and though the web-like skin may extend the whole length of the digits and be so narrow as to prevent the spread of the toes, it may, I think, be maintained that the unity of the digits is unimpaired. For the present the nature of this variation in the pigeon's feet must be regarded as doubtful, and we should note that if it is actually an example of a more perfect division being dominant to a less perfect division, the case is a marked exception to the general rule that non-division is dominant to division. Reference must also be made to the phenomenon of fasciation in the stems of plants. As Mendel showed in the case of _Pisum_ this condition is often a recessive. The appearances suggest that the difference between a normal and a fasciated plant consists in the inability of the fasciated plant to separate its lateral branches. The nature of the condition is however very obscure and it is equally likely that some multiplication of the growing point is the essential phenomenon.[15] Stockard's interesting experiments[16] illustrate this question. He showed that by treating the embryos of a fish (_Fundulus heteroclitus_) with a dilute solution of magnesium salts, various cyclopian monstrosities were frequently produced. These have been called cases of _fusion_ of the optic vesicles. I would prefer to regard them as cases of a division suppressed or restricted by the control of the environment. Conversely, the splendid discovery of Loeb, that an unfertilised egg will divide and develop parthenogenetically without fertilisation, as a consequence of exposure to various media, may be interpreted as suggesting that the action of those media releases the strains already present in the ovum, though I admit that an interpretation based on the converse hypothesis, that the medium acts as a stimulus, is as yet by no means excluded. In these cases we come nearest to the direct causation or the direct inhibition of a division, but the meaning of the evidence is still ambiguous. I incline to compare Loeb's parthenogenesis with the development (and of course accompanying cell-division) of dormant buds on stems which have been cut back. It is interesting to note that sometimes as an abnormality, the faculty of division gets out of hand and runs a course apparently uncontrolled. A remarkable instance of this condition is seen in _Begonia_ "_phyllomaniaca_", which breaks out into buds at any point on the stem, petioles, or leaves, each bud having, like other buds, the power of becoming a new plant if removed. We would give much to know the genetic properties of _B. phyllomaniaca_, and in conjunction with Mr. W. O. Backhouse I have for some time been experimenting with this plant. It proved totally sterile. Its own anthers produce no pollen, and all attempts to fertilise it with other species failed though the pollen of a great number of forms was tried. Recently however we have succeeded in making plants which are in every respect _Begonia phyllomaniaca_, so far as the characters of stems and leaves are concerned. These plants, of which we have sixteen, were made by fertilising _B. heracleifolia_ with _B. polyantha_. They are all beginning to break out in "phyllomania." As yet they have not flowered, but as they agree in all details with _phyllomaniaca_ there can be little doubt that the original plant bearing that name was a hybrid similarly produced. The production of "phyllomania" on a hybrid Begonia has also been previously recorded by Duchartre.[17] In this case the cross was made between _B. incarnata_ and _lucida_. The synonymy of the last species is unfortunately obscure, and I have not succeeded in repeating the experiment. [Illustration: FIG. 5. Piece of petiole of _Begonia phyllomaniaca_. The proximal end is to the right of the figure.] From these facts it seems practically certain that the condition is one which is due to the meeting of complementary factors. At first sight we may incline to think that the phyllomania is in some way due to the sterility. This however cannot be seriously maintained; for not only is sterility in plants not usually associated with such manifestations, but we know a Begonia called "Wilhelma" which is exactly _phyllomaniaca_ and equally sterile, though it has no trace of phyllomania. This plant arose in the nurseries of MM. P. Bruant of Poitiers, and has generally been described as a seedling of _phyllomaniaca_, but from the total sterility of that form this account of its origin must be set aside. [Illustration: FIG. 6. Two right hind feet of polydactyle cats. _II_ shows the lowest development of the condition yet recorded. The digit, _d_^{1}, which stands as hallux is fully formed and has three phalanges. Both it and the digit marked _d_^{2} are formed as _left_ digits. In the normal hind foot of the cat the hallux is represented by a rudiment only. _I_ shows a further development of the condition. In this foot there are _six_ digits. _d_^{1} has two phalanges, but both it and _d_^{2} and _d_^{3} are shaped as left digits. Thus _d_^{3}, which in the normal foot would be shaped as a right digit, is transformed so as to look like a _left_ digit.] The phenomenon in this case can hardly be regarded as due to the excitation of dormant buds, for it is apparent on examination that the new growths are not placed in any fixed geometrical relation to the original plant. They arise on the petiole, for example, as small green outgrowths each of which gradually becomes a tiny leaf. The attitude of these leaves is quite indeterminate, and they may point in any direction, some having their apices turned peripherally, some centrally, and others in various oblique or transverse positions (Fig. 5). These little leaves are thus comparable with seedlings, in that their polarity is not related to, or consequent upon that of the parent plant. They have in fact that "individuality," which we associate with germinal reproduction. There are many curious phenomena seen in the behaviour of parts normally repeated in bilateral symmetry which may some day guide us towards an understanding of the mechanics of division. A part like a hand, which needs the other hand to complete its symmetry, cannot twin by mere division, yet by proliferation and special modifications on the radial side of the same limb, even a hand may be twinned. In the well known polydactyle cats a change of this kind is very common and indeed almost the rule. When extra digits appear at the inner (tibial) side of the limb, they are shaped as digits of the other side, and even the normal digit II (index) is usually converted into the mirror-image of its normal self. The limb then develops a new symmetry in itself. Nevertheless it is not easy to interpret these facts as meaning that there has been some interruption in the control which one side of the body exercises over the other. The heredity of polydactylism is complex but there is little doubt that the condition familiar in the Cat is a dominant. In some human cases also the descent is that of a dominant, but irregularities are so frequent that no general rule can yet be perceived. The dominance of such a condition is an exception to the principle that the less-divided is usually dominant to the more-divided, a fact which probably should be interpreted as meaning that divisions are of more than one kind. Among ordinary somatic divisions, whether of organs, cells, or patterns of differentiation, the control of symmetry is usually manifested. There is however one class of somatic differentiations which are exceptionally interesting from the fact that they may show a complete independence of such geometrical control. The most familiar examples of these geometrically uncontrolled Variations are to be seen in bud-sports. The normal differentiation of the organs of a plant is arranged on a definite geometrical system, which to those who have never given special attention to such things before, will often seem surprisingly precise. The arrangement of the leaves on uninjured, free-growing shoots can generally be seen to follow a very definite order, just as do the flowers or the parts of the flowers. If however bud sports occur, then though the parts included in the sports show all the geometrical peculiarities proper to the sport-variety, yet the sporting-buds themselves are not related to each other according to any geometrical plan. A very familiar illustration is provided by the distribution of colour in those Carnations that are not self-coloured. The pigment may, as in Picotees, be distributed peripherally with great regularity to the edges of the petals; or, as in Bizarres and Flakes, it may be scattered in radial sectors which show no geometrical regularity. Now in this case the pigments are the same in both types of flower, and the chemical factors concerned in their production must surely be the same. The difference must lie in the mechanical processes of distribution of the pigment. In the Picotee we see the orderly differentiation which we associate with normality; in the Bizarre we see the disorderly differentiation characteristic of bud-sports. The distribution of colour in this case lies outside the scheme of symmetry of the plant. Such a distribution is characteristic of bud-sports, and of certain other differentiations in both plants and animals, which I cannot on this occasion discuss. Now reflexion will show that these facts have an intimate bearing on the mechanical problems of heredity. For first in the bud-sports we are witnessing the distribution of factors which distinguish genetic varieties. We do not know the physical nature of those factors, but if we must give them a name, I suppose we should call them "ferments" exactly as Boyle did in 1666. He is discussing how it comes about that a bud, budded on a stock, becomes a branch bearing the fruit of its special kind. He notes that though the bud inserted be "not so big oftentimes as a Pea," yet "whether by the help of some peculiar kind of Strainer or by the Operation of some powerful Ferment lodged in it, or by both these, or some other cause," the sap is "so far changed as to constitute a Fruit quite otherwise qualify'd."[18] We can add nothing to his speculation, and we believe still that by a differential distribution of "ferments" the sports are produced. All the factors are together present in the normal parts; some are left out in the sport. In an analogous case however, that of a variegated _Pelargonium_ which has green and also albino shoots, Baur proved that the shoots pure in colour are also pure in their posterity. There can be no doubt that the sports of Carnations, Azaleas, Chrysanthemums, etc., would behave in the same way. The well-known Azaleas Perle de Ledeburg, President Kerchove, and _Vervaeana_ are familiar illustrations. Perle de Ledeburg is predominantly white, but it has red streaks in some of its flowers. It not very rarely gives off a self-red sport. This is evidently due to the development of a bud in a red-bearing area of the stem. The red in this plant is not under "geometrical control." Many plants have white flowers with no markings, but if the red markings are geometrically ordered differentiations, no self-coloured sports are formed. The case of _Vervaeana_ is a good illustration of this proposition. It has white flowers with red markings arranged in an orderly manner on the lower parts of the petals, especially on the dorsal petals. This is one of the Azaleas most liable to have red sports, and at first sight it might seem that the sport represented the red of the central marks. Examination however of a good many flowers shows that irregular red streaks like those of Perle de Ledeburg occur, about as commonly as in that variety. _Vervaeana_ in fact is Perle de Ledeburg with _definite_ red markings added, and its red sports obviously are those branches the germs of which came in a patch of the stem bearing these red elements. That this is the true account is rendered quite obvious by the fact that the red of the sport is a colour somewhat different from that of the definite marks, and that these marks are still present on the red ground of the sporting flowers. It will be understood that these remarks apply to those cases in which the production of sports is habitual or frequent, and I imagine in all such examples it will be found that there are indications of irregularity in the distribution of the differentiations such as to justify the view that they are not under that geometrical control which governs the normal differentiation of the parts. The question next arises whether these considerations apply also to the production of a bud-sport as a rare exception, but by the nature of the case it is not possible to say positively whether the appearance of an exceptional sport is due to the unsuspected presence of a pre-existing fragment of material having a special constitution, or to the origin, _de novo_, of such a material. For instance one of the garden forms of _Pelargonium_ known as _altum_ is liable perhaps once in some hundreds of flowers to have one or two magenta petals. The normal colour is a brilliant red; and as we may be fairly sure that this red is recessive to magenta the interpretation would be quite different according as the appearance of the magenta is regarded as due to the presence of small areas endowed with magentaness, or to the spontaneous generation of the factor for that pigment. Either interpretation is possible on the facts, but the view that the whole plant has in it scarce mosaic particles of magenta seems on the whole more consistent with present knowledge. In _Pelargonium altum_ the enzyme causing the magenta colours must be distributed in very small areas, but a case in which the magenta is similarly arranged in a much coarser patchwork may be seen in the _Pelargonium_ "Don Juan," which often bears whole trusses or branches of red flowers upon plants having the normal dominant magenta trusses. In most cases there is little doubt that though the magenta flowered parts can "sport" to red, the red parts could not produce the magenta flowers. The asymmetrical, or to speak more precisely, the disorderly, mingling of the colours in the somatic parts is thus an indication of a similarly disorderly mixing of the factors for those colours in the germ-tissues, so that some of the gametes bear enough of the colour-factors to make a self-coloured plant, while others bear so little that the plant to which they give rise is a patchwork. If this view is correct we may extend it so far as to consider whether the fineness or coarseness of the mixture visible in the flowers or leaves may not give an indication of the degree to which the factors are subdivided among the germ-cells. We know very little about the genetic properties of striped varieties. In both _Antirrhinum_ and _Mirabilis_ it has been found that the striped may occasionally and irregularly throw self-coloured plants, and therefore the striping cannot be regarded simply as a recessive character. On the other hand in _Primula Sinensis_ there are well-known flaked varieties which ordinarily at least breed true. Whether these ever throw selfs I do not know, but if they do it must be quite exceptionally. The power of these flaked plants to breed true is, I suspect, connected with the fact that in their flowers the coloured and white parts are _intimately_ mixed, this intimate mixture thus being an indication of a similarly intimate mixture in the germ-cells. It would be important to ascertain whether self-fertilised seed from the occasional flowers in which the colour has run together to join a large patch gives more self-coloured plants than the intimately flaked flowers do. The next fact may eventually prove of great importance. We have seen that in bud-sports the differentiation is of the same nature as that between pure types, and also that in the sporting plant this differentiation is distributed without any reference to the plant's axis, or any other consideration of symmetry. Now among the germ-cells of a Mendelian hybrid exactly such characters are being distributed allelomorphically, and there again we have strong evidence for believing that the distribution obeys no pattern. For example, we can in the case of seeds still _in situ_ perceive how the characters were distributed among the germ-cells, and there is certainly no obvious pattern connecting them, nor can we suppose that there is an actual pattern obscured. Of this one illustration is especially curious. Individual plants of the same species are, as regards the decussations of their leaves and in other respects, _either rights or lefts_. The fact is not emphasized in modern botany and is in some danger of being forgotten. When, as in the flowers of Arum, some _Gladioli_, _Exacum_, _St. Paulia_, or the fruits of _Loasa_, rights and lefts occur on the same stem, they come off alternately. But if, as in the seedlings of Barley the twist of the first leaf be examined, it will be seen to be either a right-or left-handed screw. An ear of barley, say a two-row barley, is a definitely symmetrical structure. The seeds stand in their envelopes back to back in definite positions. Each has its organs placed in perfectly definite places. _If these seeds were buds_ their differentiations would be grouped into a common plan. One might expect that the differentiations of these embryos would still fall into the pattern; but they do not, and so far as I have tested them, any one may be a right or a left, just as each may carry any of the Mendelian allelomorphs possessed by the parent plant, without reference to the differentiation of any other seed. The fertilisation may be responsible, but our experience of the allelomorphic characters suggest that the irregularity is in the egg-cells themselves.[19] _Germ cells thus differ from somatic cells in the fact that their differentiations are outside the geometrical order which governs the differentiation of the somatic cells._ I can think of possible exceptions, but I have confidence that the rule is true and I regard it as of great significance. The old riddle, what is an individual, finds at least a partial solution in the reply that an individual is a group of parts differentiated in a geometrically interdependent order. With the germ-cell a new geometrical order, with independent polarity is almost if not quite always, begun, and with this geometrical independence the power of rejuvenescence may possibly be associated. The problems thus raised are unsolved, but they do not look insoluble. The solution may be nearer than we have thought. In a study of the geometry of differentiation, germinal and somatic, there is a way of watching and perhaps analyzing what may be distinguished as the mechanical phenomena of heredity. If any one could in the cases of the Picotee and the Bizarre Carnation, respectively, detect the real distinction between the two types of distribution, he would make a most notable advance. Any one acquainted with mechanical devices can construct a model which will reproduce some of these distinctions more or less faithfully. The point I would not lose sight of is that the analogy with such models must for a long way be a true and valuable guide. I trust that some one with the right intellectual equipment will endeavor to follow this guide; and I am sanguine enough to think that a comprehensive study of the geometrical phenomena of differentiation will suggest to a penetrative mind that critical experiment which may one day reveal the meaning of spontaneous division, the mystery through which lies the road, perhaps the most hopeful, to a knowledge of the nature of life. FOOTNOTES: [1] In saying this we make no assumption as to the particular cell-division at which differentiation occurs. This may be one of the maturation-divisions, or it may perhaps be much earlier. [2] From the recent discoveries of Erwin Baur we are led to surmise that in the flowering plants the sub-epidermal layer, or some of its elements, may legitimately be regarded as a similar germ-substance, continuous in Weismann's sense. [3] These fraternal twins, which show no special resemblance to each other, are like the multiple births of other animals, and there is no disposition for them to be of the same sex. In the sheep, for example, statistics show that the frequency of pairs of twins, male and female, is approximately double that of the frequency of pairs, both male or both female, as it should be if the sex-distribution were fortuitous. For instance Bernadin (_La Bergerie de Rambouillet_, 1890, p. 100) gives the following figures for twin-lambs in Merinos: both male, 87; both female, 83; sexes mixed, 187. The 9-banded Armadillo (_Dasypus novemcinctus_), in which the young born in one litter are said to be always of one sex, is the only known exception in Vertebrates, and is presumably a genuine case of normal polyembryony (see especially, Rosner, _Bull. Ac. Soc. Cracovie_, 1901, p. 443, and Newman and Patterson, _Biol. Bull._, XVII, 1909, p. 181), and an important paper lately published by H. H. Newman and J. T. Patterson, _Jour. Morph._, 1911, XXII, p. 855. [4] A good collection of evidence as to disease in homologous twins was lately published by E. A. Cockayne, _Brit. Jour. Child. Diseases_, Nov., 1911. [5] Cp. Windle, B. C. A., _Jour. Anal. Phys._, XXVI, p. 295. [6] Mr. E. Nettleship tells me that in the course of collecting pedigrees of families containing colour-blind members he has discovered two cases (shortly to be published) of pairs of twins, which on account of their very close resemblances must be deemed homologous, one of each pair being colour-blind and the other normal. Such a distinction between closely similar twins is most curious and unexpected. [7] Another paradoxical phenomenon of the same nature occurs in the Narwhal The males normally have the _left_ tusk alone developed, the corresponding right tusk remaining as an undeveloped rudiment in its socket. The left tusk is a left-handed screw. Occasionally the right tusk is also developed and grows to the same length as that of the left side, but in such specimens the right tusk is also a left-hand screw like the tusk of the other side, instead of being reversed as we should certainly have expected. It need scarcely be remarked that in the case of the horns of antelopes, and in other examples of spiral organs arranged in pairs, that of one side of the body is the mirror image of that on the other side. The Narwhal's tusks in being both twisted in the same direction are thus highly anomalous, and are comparable with pairs of twins. [8] Wilder, H. H., _Amer. Jour. Anat._, 1904, III, p. 452. [9] Polydactylism which is often a dominant and the web-foot of Pigeons which is recessive should be remembered as possible exceptions (see p. 49). [10] Davenport inclined at first to regard rumplessness as a recessive, but in his latest publication on the subject he definitely concludes that it is an imperfect dominant. This conclusion accords well with evidence quoted by Darwin (_An. and Plts._, II, ed. 2, p. 4) that rumpless fowls may throw tailed offspring. (_Amer. Nat._, 1910, XLIV, p. 134.) [11] Spillman, W. J., _Amer. Breeders Mag._, 1910, I, p. 178. [12] Newsholme, _Lancet_, December 10, 1910, p. 1690. [13] _Materials for the Study of Variation_, 1894, p. 358. [14] Walker, G., _Johns Hopkins Hospital Bulletin_, XII, 1901, p. 129. [15] Cp. R. H. Compton, _New Phytologist_, 1911, p. 249. [16] _Arch. f. Entwickelungsmech._, 1907, XXIII, p. 249. [17] Bull. Soc. Bot. de France, xxxiv, 1887, p. 182. [18] R. Boyle, _The Origine of Formes and Qualities_, Oxford, 1666. [19] Remarkable experiments on this question have lately been carried out by R. H. Compton (_Camb. Phil. Soc._, XV, 1910, p. 495), showing that in a certain Barley, "Plumage Corn," the average ratio of left to right is about 1.5. A fuller paper has since been published by Compton, _Jour. Genetics_, 1912, II, I, p. 53. CHAPTER III SEGMENTATION, ORGANIC AND MECHANICAL Models may be and often have been devised imitating some of the phenomena of division, but none of them have reproduced the peculiarity which characterises divisions of living tissues, that _the position of chemical differentiation_ is _determined by those divisions_. For example, models of segmentation, whether radial or linear, may be made by the vibration of plates as in the familiar Chladni figures of the physical laboratory, or by the bowing of a tube dusted on the inside with lycopodium powder, and in various other ways. The sand or the powder will be heaped up in the nodes or regions of least movement, and the patterns thus formed reproduce many of the geometrical features of segmentation. But in the segmentations of living things the nodes and internodes, once determined by the dividing forces, would each become the seat of appropriate and distinct chemical processes leading to the differentiation of the parts, and the deposition of the bones, petals, spines, hairs, and other organs in relation to the meristic ground-plan. The "ripples" of meristic division not merely divide but differentiate, and when a "ripple" forks the result is not merely a division but a reduplication of the organ through which the fork runs. An example illustrating such a consequence is that of the half-vertebrae of the Python. On the left side the vertebra is single (Fig. 7) and bears a single rib, but on the right side a division has occurred with the result that two half-vertebrae, each bearing a rib, are formed, one standing in succession to the other. We cannot, indeed, imagine any operation of physiological division carried out in such an organ as a vertebra, passing through a plane at right angles to the long axis of the body, which does not necessarily involve the further process of reduplication. As the meristic system of distribution spreads through the body, chemical differentiations follow in its track, with segmentation and pattern as the visible result. Could we analyse these simultaneous phenomena and show how it is that the places of chemical differentiation are determined by the system of division, progress would then be rapid. It is here that all speculation fails. [Illustration: FIGS. 7 and 8. Two examples of imperfect division in the vertebræ of a python. _I_, the vertebræ 147-150 from the right side, showing imperfect division between the 148th and 149th. The condition on the left side of this vertebra was the same. _II_, the dorsal surface of vertebræ 165-167. On the right side the 166th is double and bears two ribs, but on the left side it is normal and has one rib only.] Many attempts have been made to interpret the processes of division and repetition, in terms of mechanics, or at least to refer them to their nearest mechanical analogies, so far with little success. The problem is beset with difficulties as yet insurmountable and of these one must be especially noticed. In the living thing the process by which repetition and patterns come into being consists partly in division but partly also in growth. We have no means of studying the phenomena of pattern-formation except in association with that of growth. Growth soon ceases unless division takes place, and if growth is impossible division soon ceases also. In consequence of this fact that the final pattern is partly a product of growth, it can never be used as unimpeachable evidence of the primary geometrical relations of the members as laid down in the divisions. In the last chapter in referring to the problem of repetition I introduced an analogy, comparing the patterns of the organic world with those produced in unorganised materials by wave-motion. In the preliminary stage of ignorance, having no more trustworthy clue, I do not think it wholly unprofitable to consider the applicability of this analogy somewhat more fully. It possesses, as I hope to show, at least so much validity as to encourage the belief that morphology may safely discard one source of long-standing error and confusion. Those who have studied the structure of parts repeated in series will have encountered the old morphological problem of "Serial Homology," which has absorbed so much of the attention of naturalists and especially of zoologists at various periods. This problem includes two separate questions. The first of these is the origin in evolution of the resemblance between two organs occurring in a repeated series, of which the fore and hind limbs of Vertebrates are the prerogative instance. From the fact that these resemblances can be traced very far, often into minute details of structure, many anatomists have inclined to the opinion that the resemblance must originally have been still more complete, and that the two limbs, for instance, must have acquired their present forms by the differentiation of two identical groups of parts. Similar questions arise whenever parts are repeated in series, whether the series be linear or radial, and, though less obviously, even when the repetition is bilateral only. In each such example the question arises, is the resemblance between the parts the remains of a still closer resemblance, or is differentiation original? Sometimes the view that these parts have arisen by the differentiation of a series of identical parts is plausible enough, as for example when the peculiarities of various appendages of a Decapod Crustacean are referred to modifications of the Phyllopod series. In application to other cases however we soon meet with difficulty, and the suggestion that the segments of a vertebrate were originally all alike is seen at once to be absurd, for the reason that a creature so constituted could not exist, and that, differentiation of at least one anterior and one posterior segment, is an essential condition of a viable organism consisting of parts repeated in a linear series. Between these two terminal segments it is possible to imagine the addition of one segment, or of a series of approximately similar segments; but when once it is realised that the terminals must have been differentiated from the beginning, it will be seen that the problem of the origin of the resemblance between segments is not rendered more comprehensible by the suggestion that even the intervening members were originally alike. Seeing indeed that some differentiation must have existed primordially it is as easy to imagine that the original body was composed of a series grading from the condition of the anterior segment to that of the posterior, as any other arrangement. The existence of a linear or successive series in fact postulates a polarity of the whole, and in such a system the conception of an ideal segment containing all the parts represented in the others has manifestly no place. The introduction of that conception though sanctioned by the great masters of comparative anatomy, has, as I think, really delayed the progress of a rational study of the phenomena of division. The same notion has been applied to every class of repetition both in animals and plants, generally with the same unhappy results. In the cruder forms in which this doctrine was taught thirty years ago it is now seldom expressed, but modified presentations of it still survive and confuse our judgments. The process of repetition of parts in the bodies of organisms is however a periodic phenomenon. This much, provided we remain free from prejudice as to the nature and causation of the period or rhythm, we may safely declare, and a comparison may thus be instituted between the consequences of meristic repetition in the bodies of living things and those repetitions which in the inorganic world are due to rhythmical processes. Of such processes there is a practically unlimited diversity and we have nothing to indicate with which of them our repetitions should rather be compared. [Illustration: FIG. 9. Osmotic growths simulating segmentation. (After Leduc.)] In some respects perhaps the best models of living organisms yet made are the "osmotic growths" produced by Leduc.[1] These curious structures were formed by placing a fragment of a salt, for instance calcium chloride, in a solution of some colloidal substance. As the solid takes up water from the solution a permeable pellicle or membrane is formed around it. The vesicle thus enclosed grows by further absorption of water, often extending in a linear direction, and in many examples this growth occurs by a series of rhythmically interrupted extensions. Some of the growths thus formed are remarkably like organic structures, and might pass for a series of antennary segments or many other organs consisting of a linear series of repeated parts. In admitting the essential resemblance between these "osmotic growths" and living bodies or their organs I lay less stress on the general conformation of the growths, which often as Leduc points out, recall the forms of fungi or hydroids, but rather on the fact that the interruptions in the development of these systems are so closely analogous to the segmentations or repetitions of parts characteristic of living things (Fig. 9). In the same way I am less impressed by Leduc's models of Karyokinesis, wonderful as they nevertheless are, for the division is here imitated by putting separate drops on the gelatine film. What we most want to know is how in the living creature one drop becomes two. The models of linear segmentation have the remarkable merit that they do in some measure imitate the process of actual division or repetition. So in a somewhat modified method Leduc, by causing the diffusion of a solution in a gelatine film, produced rhythmical or periodic precipitations strikingly reminiscent of various organic tissues, for here also the process of periodic repetition is imitated with success. It is a feature common to these and to all other rhythmical repetitions produced by purely mechanical forces that there is resemblance between the members of the series, and that this similarity of conformation may be maintained in most complex detail. When however in the mechanical series some of the members differ from the rest we have no difficulty in recognising that these differences--which correspond with the differentiations of the organic series--are due to special heterogeneity in the conditions or in the materials, and it never occurs to us to suppose that all the members must have been primordially alike. For example, in the case of ripple-marks on the sand, which I choose as one of the most familiar and obvious illustrations of a repeated series due to mechanical agencies, if we notice one ripple different in form from those adjacent to it, we do not suppose that this variation must have been brought about by deformation of a ripple which was at first formed like the others, but we ascribe it to a difference in the sand at that point, or to a difference in the way in which the wind or the tide dealt with it. We may press the analogy further by observing that in as much as such a series of waves has a beginning and an end, it possesses polarity like that of the various linear series of parts in organisms, and even the formation of each member must influence the shape of its successor. Since in an organism the beginning and end of the series are always included, some differentiation among the repetitions must be inevitable. If therefore it be conceded, as I think it must, that segmentation and pattern are the consequence of a periodic process we realize that it is at least as easy to imagine the formation of such a series of parts having family likeness combined with differentiation as it would be to conceive of their arising primordially as a series of identical repetitions. The suggestion that the likenesses which we now perceive are the remains of a still more complete resemblance is a substitution of a more complex conception for a simpler one. The other question raised by the problem of Serial Homology is how far there is a correspondence between individual members of series when the series differ from each other either in the number of parts, or in the mode of distribution of differentiation among them. Students, for example, of vertebrate morphology debate whether the _n_th vertebra which carries the pelvic girdle in Lizard A is individually homologous with the _n_ + _x_th vertebra which fulfils this function in Lizard B, or whether it is not more truly homologous with the vertebra standing in the _n_th ordinal position, though that vertebra in Lizard B is free. In various and more complex aspects the same question is debated in regard to the cranial and spinal nerves, the branches of the aorta, the appendages of Arthropoda, and indeed in regard to all such series of differentiated parts in linear or successive repetition. Persons exercised with these problems should before making up their minds consider how similar questions would be answered in the case of any series of rhythmical repetitions formed by mechanical agencies. In the case of our illustration of the ripples in the sand, given the same forces acting on the same materials in the same area, the number of ripples produced will be the same, and the _n_th ripple counting from the end of the series will stand in the same place whenever the series is evoked. If any of the conditions be changed, the number and shapes can be changed too, and a fresh "distribution of differentiation" created. Stated in this form it is evident that the considerations which would guide the judgment in the case of the sand ripples are not essentially different from those which govern the problem of individual homology in its application to vertebrae, nerves, or digits. The fact that the unit of repetition is also the unit of growth is the source of the obscurity which veils the process. When we compare the skeleton of a long-tailed monkey with that of a short-tailed or tailless ape we see at once how readily the additional series of caudal segments may be described as a consequence of the propagation of the "waves" of segmentation beyond the point where they die out in the shorter column, and we see that with an extension of the series of repetitions there is growth and extension of material. The considerations which apply to this example will be found operating in many cases of the variation of terminal members of linear series. Some of these series, like the teeth of the dog, end in a terminal member of a size greatly reduced below that of the next to it. Even when there is thus a definite specialisation of the last member of the series it not infrequently happens that the addition, by variation, of a member beyond the normal terminal, is accompanied by a very palpable increase in size of the member which stands numerically in the place of the normal terminal.[2] So also with variation in the number of ribs, when a lumbar vertebra varies homoeotically into the likeness of the last dorsal and bears a rib, the rib placed next in front of this, which in the normal trunk is the last, shows a definite increase in development. The consequences of such homoeoses are sometimes very extensive, involving readjustments of differentiation affecting a long series of members, as may easily be seen by comparing the vertebral columns of several individual Sloths[3] (whether _Bradypus_ or _Choloepus_) to take a specially striking example. It may be urged that no feature as yet enables us to perceive wherein lies the primary distinction which determines such variation, whether it is due to a difference in the dividing forces or in the material to be divided. If for instance we were to imitate such a series of segments by pressing hanging drops of a viscous fluid out of a paint-tube by successive squeezes, the number of times the tube is contracted before it is empty will give the number of the segments, but their size may depend either on the force of the contractions or on the capacity of the tube, or on various other factors. Nevertheless in the case of the variation of terminal members, whatever be the nature of the rhythmical impulse which produces the series of organs, the elevation of the normally terminal member in correspondence with the addition of another is what we should expect. If the organism acquired its full size first and the delimitation of the parts took place afterwards, there might be some hope that the resemblance between living patterns and those mechanically caused by wave-motion might be shown to be a consequence of some real similarity of causation, but in view of the part played by growth, appeal to these mechanical phenomena cannot be declared to have more than illustrative value. Similarly in as much as living patterns appear, and almost certainly do in reality come into existence by a rhythmical process, comparisons of these patterns with those developed in crystalline structures, and in the various fields of force are, as it seems to me, inadmissible, or at least inappropriate. However their intermittence be determined, the rhythms of division must be looked upon as the immediate source of those geometrically ordered repetitions universally characteristic of organic life. In the same category we may thus group the segmentation of the Vertebrates and of the Arthropods, the concentric growth of the Lamellibranch shells or of Fishes' scales, the ripples on the horns of a goat, or the skeletons of the Foraminifera or of the Heliozoa. In the case of plant-structures Church[4] has admirably shown, with an abundance of detail, how on analysis the definiteness of phyllotaxis is an expression of such rhythm in the division of the apical tissues, and how the spirals and "orthostichies" displayed in the grown plant are its ultimate consequences. The problem thus narrows itself down to the question of the mode whereby these rhythms are determined. It is natural that we should incline to refer them to a chemical source. If we think of the illustration just given, of the segmentation of a viscous fluid into drops by successive contractions of a soft-walled tube we can, I think, conceive of such rhythmic contractions as due to summations of chemical stimuli, somewhat as are the beats of the heart. But when we recognize the vast diversity of materials the distribution of which is determined by an ostensibly similar rhythmic process it seems hopeless to look forward to a directly chemical solution. That the chemical degradation of protoplasm or of materials which it contains is the source of the energy used in the divisions cannot be in dispute, but that these divisions can be themselves the manifestations of chemical action seems in the highest degree improbable. We may therefore insist with some confidence on the distinction between the Meristic and the substantive constitution of organisms, between, that is to say, the system according to which the materials are divided and the essential composition of the materials, conscious of the fact that the energy of division is supplied from the materials, and that in the ontogeny the manner in which the divisions are effected must depend secondarily on the nature of the substances to be divided. The mechanical processes of division remain a distinguishable group of phenomena, and variations in the substances to be distributed in division may be independent of variations in the system by which the distribution is effected. Modern genetic analysis supplies many remarkable examples of this distinction. When formerly we compared the leaves of a normal palmatifid Chinese Primula with the pinnatifid leaves[5] of its fern-leaved variety we were quite unable to say whether the difference between the two types of leaf was due to a difference in the material cut up in the process of division or to a difference in that process itself. Knowledge that the distinction is determined by a single segregable factor tends to prove that the critical difference is one of substance. So also in the Silky fowl we know that the condition of its feathers is due to the absence of some one factor present in the normal form. We may conceive such differences as due to change of form in the successive "waves" of division, but we cannot yet imagine segregation otherwise than as acting by the removal or retention of a material element. Future observation by some novel method may suggest some other possibility, but such cases bring before us very clearly the difficulties by which the problem is beset. [Illustration: FIG. 10. The palm-and fern type of leaf in _Primula Sinensis_. The palm is dominant and the fern is recessive.] In another region of observation phenomena occur which as it seems to me put it beyond question that the meristic forces are essentially independent of the materials upon which they act, save, in the remoter sense, in so far as these materials are the sources of energy. The physiology of those regenerations and repetitions which follow upon mutilation supplies a group of facts which both stimulate and limit speculation. No satisfactory interpretations of these extraordinary occurrences has ever been found, but we already know enough to feel sure that in them we are witnessing indications which should lead to the discovery of the true mechanics of repetition and pattern. The consequences of mutilation in causing new growth or perhaps more strictly in enabling new growth to take place, are such that they cannot be interpreted as responses to chemical stimuli in any sense which the word chemical at present connotes. Powers are released by mutilation of which in the normal conditions of life no sign can be detected. All who have tried to analyse the phenomena of regeneration are compelled to have recourse to the metaphor of equilibrium, speaking of the normal body as in a state of strain or tension (Morgan) which when disturbed by mutilation results in new division and growth. The forces of division are inacessible to ordinary means of stimulation. Applications, for example, of heat or of electricity excite no responses of a positive kind unless the stimuli are so violent as to bring about actual destruction.[6] These agents do not, to use a loose expression, come into touch with the meristic forces. Changes in the chemical environment of cells may, as in the experiments of Loeb and of Stockard produce definite effects, but the facts suggest that these effects are due rather to alterations in the living material than to influence exerted directly on the forces of division themselves. By destruction of tissue however the forces both of growth and of division also may often be called into action with a resulting regeneration. Interruption of the solid connexion between the parts may produce the same effects, as for example when the new heads or tails grow on the divided edges of Planarians (Morgan), or when from each half embryo partially separated from its normally corresponding half, a new half is formed with a twin monster as the result. Often classed with regenerations but in reality quite distinct from them are those special and most interesting examples where the growth of a _paired_ structure is excited by a simple wound. Some of the best known of these instances are presented by the paired extra appendages of Insects and Crustacea. Some years ago I made an examination of all the examples of such monstrosities to which access was to be obtained, and it was with no ordinary feeling of excitement that I found that these supernumerary structures were commonly disposed on a recognizable geometrical plan, having definite spatial relations both to each other and to the normal limb from which they grew. The more recent researches of Tornier[7] and especially his experiments on the Frog have shown that a cut into the posterior limb-bud induces the outgrowth of such a _pair_ of limbs at the wounded place. Few observations can compare with this in novelty or significance; and though we cannot yet interpret these phenomena or place them in their proper relations with normal occurrences, we feel convinced that here is an observation which is no mere isolated curiosity but a discovery destined to throw a new light on biological mechanics. The supernumerary legs of the Frog are evidently grouped in a system of symmetry similar to that which those of the Arthropods exhibit, and though in Arthropods paired repetitions have not been actually produced by injury under experimental conditions we need now have no hesitation in referring them to these causes as Przibram has done. At this point some of the special features of the supernumerary appendages become important. First they may arise at any point on the normal limb, being found in all situations from the base to the apex. Nor are they limited as to the surface from which they spring, arising sometimes from the dorsal, anterior, ventral, or posterior surfaces, or at points intermediate between these principal surfaces. With rare and dubious exceptions, the parts which are contained in these extra appendages are only those which lie _peripheral to their point of origin_. Thus when the point of origin is in the apical joint of the tarsus, the extra growth if completely developed consists of a double tarsal apex bearing two pairs of claws. If they arise from the tibia, two complete tarsi are added. If they spring from the actual base of the appendage then two complete appendages may be developed in addition to the normal one. We must therefore conclude that in any point on a normal appendage the power exists which, if released, may produce a bud containing in it a paired set of the parts peripheral to this point. [Illustration: FIG. 11. Diagrams of the geometrical relations which are generally exhibited by extra pairs of appendages in Arthropoda. The sections are supposed to be those of the apex of a tibia in a beetle. _A_, anterior, _P_, posterior, _D_, dorsal, _V_, ventral. _M_^{1}, _M_^{2} are the imaginary planes of reflexion. The shaded figure is in each case a limb formed like that of the other side of the body, and the outer unshaded figures are shaped like the normal for the side on which the appendages are. On the several radii are shown the extra pairs in their several possible relations to the normal from which they arise. The normal is drawn in thick lines in the center.] Next the geometrical relations of the halves of the supernumerary pair are determined by the position in which they stand in regard to the original appendage. These relations are best explained by the diagram (Fig. 11), from which it will be seen that the two supernumerary appendages stand as images of each other; and, of them, that which is adjacent to the normal appendage forms an image of it. Thus if the supernumerary pair arise from a point on the dorsal surface of the normal appendage, the two _ventral_ surfaces of the extra pair will face each other. If they arise on the anterior surface of the normal appendage, their morphologically posterior surfaces will be adjacent, and so on. These facts give us a view of the relations of the two halves of a dividing bud very different from that which is to be derived from the exclusive study of normal structures. Ordinary morphological conceptions no longer apply. The distribution of the parts shows that the bud or rudiment which becomes the supernumerary pair may break or open out in various ways according to its relations to the normal limb. Its planes of division are decided by its geometrical relations to the normal body. Especially curious are some of the cases in which the extra pair are imperfectly formed. The appearance produced is then that of two limbs in various stages of coalescence, though in reality of course they are stages of imperfect separation. The plane of "coalescence" may fall anywhere, and the two appendages may thus be compounded with each other much as an object partially immersed in mercury "compounds" with its optical image reflected from the surface. Supernumerary paired structures are not usually, if ever, formed when an appendage is simply amputated. Cases occasionally are seen which nevertheless seem to be of this nature. Borradaile,[8] for example, described a crab (_Cancer pagurus_) having in place of the right chela three _small_ chelae arising from a common base, where the appearances suggested that the three reduced limbs replaced a single normal limb. From the details reported however it seems still possible that one of the chelae (that lettered F. I in Borradaile's figure) may be the normal one, and the other two an extra pair. The chela which I suspect to be the normal is in several respects deformed as well as being reduced in size, and this deformity may perhaps have ensued as a consequence of the same wound which excited the growth of the extra pair. Its reduced size may be due to the same injury, which may quite well have checked its growth to full proportions. Admitting doubt in these ambiguous cases it seems to be a general rule that for the production of the extra pair the normal limb should persist in connexion with the body. Moreover it is practically certain that in no case can a _single_, viz. an unpaired, duplicate of the normal appendage grow from it. Many examples have been described as of this nature, but all of them may be with confidence regarded as instances of a supernumerary pair in which only the two morphologically anterior or the two morphologically posterior surfaces are developed. We have thus the paradox that a limb of one side of the body, say the right, has in it the power to form a pair of limbs, right and left, as an outgrowth of itself, but cannot form a second left limb alone. A very interesting question arises whether it is strictly correct to describe the extra pair as a right and a left, or whether they are not rather two lefts or two rights of which one is reversed. This question did not occur to me when in former years I studied these subjects. It was suggested to me by Dr. Przibram. The answer might have an important bearing on biological mechanics, but I know no evidence from which the point can be determined with certainty. In order to decide this question it would be necessary to have cases in which the paired repetition affected a limb markedly differentiated on the two sides of the body, and of course the development of the extra parts in order to be decisive must be fairly complete. One example only is known to me which at all satisfies these requirements, that of the lobster's chela figured (after Van Beneden) in _Materials for the Study of Variation_, p. 531, Fig. 184, III. Here the drawing distinctly suggests that one of the extra dactylopodites, namely that lettered R, is differentiated as a left and not merely a reversed right. For the teeth on this dactylopodite are those of a cutting claw, not of a crushing claw, whereas the dactylopodites R' and L' bear crushing teeth. The figure makes it fairly certain also that the limb affected was a crushing claw. Accepting this interpretation, we reach the remarkable conclusion that the bud of new growth consisted of halves differentiated into cutter and crusher as the normal claws are, and that the extra crusher is geometrically a left but physiologically a right. Though shaped as a left in respect of the direction in which it points, the extra crusher is really an optically reversed right, while the dactylopodite R, which is placed pointing like a right, is really a reversed left (Fig. 12). [Illustration: FIG. 12. Right claw of lobster bearing a pair of extra dactylopodites (after van Beneden). The fine toothing on R suggests that this is part of a cutting claw, though the limb bearing it is a crusher.] If these indications are reliable[9] and are established by further observation we shall be led to the conclusion that the bud which becomes an extra pair of limbs does not merely contain the parts proper to the side on which it grows, but is comparable with the original zygotic cell, and consists not simply of two halves, but of two halves differentiated as a right and a left like the two halves of the normal body. Phenomena of this kind, evoked by mutilation or injury, together with the cognate observations on regeneration throw very curious lights on the nature of living things. To an understanding of the nature of the mechanics of living matter and its relation to matter at large they offer the most hopeful line of approach. I allude especially to the examples in which it has been established that the part which is produced after mutilation is a structure different from that which was removed. The term "regeneration" was introduced before such phenomena were discovered, and though every one recognizes its inapplicability to these remarkable cases, the word still misleads us by presenting a wrong picture to the mind. The expression "heteromorphosis" (Loeb) has been appropriately applied to various phenomena of this kind, and Morgan has given the name "morphallaxis" to another group of cases in which the renewal occurs by the transformation of a previously existing part.[10] But we must continually remember that all these occurrences which we know only as abnormalities and curiosities must in reality be exemplifications of the normal mechanics of division and growth. The conditions needed to call them forth are abnormal, but the responses which the system makes are evidences of its normal constitution. When therefore, for example, the posterior end of a worm produces a reversed tail from its cut end we have a proof that there must be in the normal body forces ready to cause this outgrowth. The new structure is not an ill-shaped head-end, for, as Morgan shows, the nephridial ducts have their funnels perforating the segments in a reversed direction. The "tension" of growth is actually reversed.[11] So also when in a Planarian amputation of the body immediately behind the head leads to the formation of a new reversed head at the back of the normal head, while amputation further back leads to the regeneration of a new tail, these responses give indications of forces normally present in the body of the Planarian. Such facts open up a great field of speculation and research. Especially important it would be to determine where the critical region may be at which the one response is replaced by the other. I suppose it is even possible that there is some neutral zone in which neither kind of response is made. Physical parallels to the phenomena of regeneration are not easy to find and we still cannot penetrate beyond the empirical facts. Przibram has laid stress on the general resemblance between the new growth of an amputated part in an animal and the way in which a broken crystal repairs itself when placed in the mother-solution. That the two processes have interesting points of likeness cannot be denied. It must however never be forgotten that there is one feature strongly distinguishing the two; for I believe it is universally recognized by physicists that all the phenomena of geometrical regularity which crystals display are ultimately dependent on the forms of the particles of the crystalline body. This cannot in any sense be supposed to hold in regard to protoplasm or its constituents. The definiteness of crystals is also an unlikely guide for the reason that it is absolute and perfect, or in other words because this kind of regularity cannot be disturbed at all without a change so great that the substance itself is altered; whereas we know that the forms of living things are capable of such changes, great and small, that we must regard perfection of form, whether manifested in symmetry or in number, as an ideal which will only be produced in the absence of disturbance. The symmetry of the living things is like the symmetry of the concentric waves in a pool caused by a splash. Perfect circles are made only in the imaginary case of mathematical uniformity, but the system maintains an approximate symmetry though liable to manifold deformation. Since the geometrical order of the living body cannot be a direct function of the materials it must be referred to some more proximate control. In renewing a part the body must possess the power of seizing particles of many dissimilar kinds, and whirl them into their several and proper places. The action in renewal, like that of original growth, may be compared--very crudely--with the action of a separator which simultaneously distributes a variety of heterogeneous materials in an orderly fashion; but in the living body the thing distributed must rather be the _appetency_ for special materials, not the materials themselves. If the analogy of crystals be set aside and we seek for other parallels to regeneration there are none very obvious. I have sometimes wondered whether it might not be possible to institute a fruitful comparison between the renewal of parts and the reformation of waves of certain classes after obliteration. In several respects, as I have already said, some curious resemblances with the repetitions formed by wave-motion are to be traced in our organic phenomena, and though admitting that I cannot develop these comparisons, I think nevertheless they may be worth bearing in mind. When, after obliteration, an eddy in a stream, or a ripple-mark (a more complex case of eddy-formation) in blown sand is re-formed, we have an example in which pattern is reconstituted and growth takes place not by virtue of the composition of the materials--in this case the water or the sand--but by the way in which they are acted upon by extraneous forces. A feature in the actual mode by which ripple-marks are reconstituted may not be without interest in connexion with our phenomena of regeneration. When, for example, the wind is blowing steadily over a surface of fine, dry sand, the familiar ripple-marks are formed by a heaping of the sand in lines transverse to the direction of the wind. The heaping is due to the formation of eddies corresponding with positions of instability. When the wind is steady and the sand homogeneous, the distances between the ripples, or wave-lengths, are sensibly equal. If while the wind continues to blow, the ripples are obliterated with a soft brush they will quickly be re-formed over the whole area, but I have noticed that at first their wave-length is approximately half that of the ripples in the undisturbed parts of the system.[12] The normal wave-length is restored by the gradual accentuation of alternate ripples. Of course the sand-ripples are in reality slowly travelling forward in the direction towards which the wind is blowing, and for this our living segmentations afford no obvious parallel, but the appearances in the area of reformation, and especially the forking of the old ridges where they join the new ones, are curiously reminiscent of the irregularities of segmentation seen in regenerated structures. The value of the considerations adduced in the chapter is, I admit, very small. The utmost that can be claimed for them is that mechanical segmentations, like those seen in ripple-mark, or in Leduc's osmotic growths, show how by the action of a continuous force in one direction, repeated and serially homologous divisions can be produced having features of similarity common to those repetitions by which organic forms and patterns are characterised. The analogy supplies a vicarious picture of the phenomena which in default of one more true may in a slight degree assist our thoughts. It suggests that the rhythms of segmentation may be the consequence of a single force definite in direction and continuously acting during the time of growth. The polarity of the organism would thus be the expression of the fact that this meristic force is definitely directed after it has once been excited, and the reversal seen in some products of regeneration suggest further that it is capable of being reflected. This polarity cannot be a property of the material, as such, but is determined by a force acting on that material, just as the polarity of a magnet is not determined by the arrangement of its particles, but by the direction in which the current flows. To some it may appear that even to embark on such discussions as this is to enter into a perilous flirtation with vitalistic theories. How, they may ask, can any force competent to produce chemical and geometrical differentiation in the body be distinguished from the "Entelechy" of Driesch? Let me admit that in this reflexion there is one element of truth. If those who proclaim a vitalistic faith intend thereby to affirm that in the processes by which growth and division are effected in the body, a part is played by an orderly force which we cannot _now_ translate into terms of any known mechanics, what observant man is not a vitalist? Driesch's first volume, putting as it does into intelligible language that positive deduction from the facts--especially of regeneration--should carry a vivid realisation of this truth to any mind. If after their existence is realised, it is desired that these unknown forces of order should have a name, and the word entelechy is proposed, the only objection I have to make is that the adoption of a term from Aristotelian philosophy carries a plain hint that we propose to relegate the future study of the problem to metaphysic. From this implication the vitalist does not shrink. But I cannot find in the facts yet known to us any justification of so hopeless a course. It was but yesterday that the study of _Entwicklungsmechanik_ was begun, and if in our slight survey we have not yet seen how the living machine is to be expressed in terms of natural knowledge that is poor cause for despair. Driesch sums up his argument thus:[13] "It seems to me that there is only one conclusion possible. If we are going to explain what happens in our harmonious-equipotential systems by the aid of causality based upon the constellation of single chemical factors and events, there _must_ be some such thing as a machine. Now the assumption of the existence of a machine proves to be absolutely absurd in the light of the experimental facts. _Therefore there can be neither any sort of a machine nor any sort of causality based upon constellation underlying the differentiation of harmonious-equipotential systems._" "For a machine, typical with regard to the three chief dimensions of space, cannot remain itself if you remove parts of it or if you rearrange its parts at will." To the last clause a note is added as follows: "The pressure experiments and the dislocation experiments come into account here; for the sake of simplicity they have not been alluded to in the main line of our argument." I doubt whether any man has sufficient knowledge of all possible machines to give reality to this statement. In spite also of the astonishing results of experiments in dislocation, doubt may further be expressed as to whether they have been tried in such variety or on such a scale as to justify the suggestion that the living organism remains itself if its parts are rearranged at will. All we know is that it can "remain itself" when much is removed, and when much rearrangement has been affected, which is a different thing altogether. I scarcely like to venture into a region of which my ignorance is so profound, but remembering the powers of eddies to re-form after partial obliteration or disturbance, I almost wonder whether they are not essentially machines which remain themselves when parts of them are removed. Real progress in this most obscure province is not likely to be made till it attracts the attention of physicists; and though they for long may have to forego the application of exact quantitative methods, I confidently anticipate that careful comparison between the phenomena of repetition formed in living organisms and the various kinds of segmentation produced by mechanical agencies would be productive of illuminating discoveries. FOOTNOTES: [1] Stéphane Leduc, _Théorie Physico-Chymique de la Vie_, Paris, 1910. [2] _Materials for the Study of Variation_, No. 249, p. 217; and p. 272. [3] _Materials_, p. 118. [4] Church, A. H., _On the Relation of Phyllotaxis to Mechanical Laws_, London, 1904. [5] It is a question whether the dominance of the palmatifid leaf over the pinnatifid is not really an example of the dominance of a lower number of segmentations over a higher. From the uncertainty whether two given leaves of two separate plants are actually comparable one cannot institute quite satisfactory numerical comparisons, but I think the view that the "Fern" leaf has more lobes than an otherwise similar "Palm" leaf may be fairly maintained. If this be admitted, the "Palm" leaf represents the dominant low number and its round shape is a consequence of the greater powers of growth which are so often possessed by the members of a shorter series. [6] It is perhaps of importance to remember that in certain species of bacteria (e. g. _Bacillus Anthracis_) division may cease where the organism is cultivated under certain artificial conditions though growth continues. In this way very long unsegmented threads are produced. [7] _Arch. f. Entwm._, XX, 1905, p. 76; _Sitzungsb. d. Ges. Naturf._, Berlin, 1907, p. 41, etc. [8] Borradaile, L. A., _Jour. Marine Zool._, 1897, No. 8. [9] Dr. Przibram, I should mention, concludes that on the whole the facts are against this interpretation, but as more evidence is certainly required, I call attention to the possibility. [10] Morgan, T. H., _Regeneration_, 1901. [11] It would be interesting to know whether growth continues at the original posterior end after the new "posterior" end has been formed in front. [12] In the actual case observed, the ripples unsmoothed had a wave-length of about 2-1/2 inches; and when the new ones were first formed, there were about 30 ridges in the length originally traversed by 15 or 16. [13] _The Science and Philosophy of the Organism_; Gifford Lectures, 1907. London, 1908, p. 141. CHAPTER IV THE CLASSIFICATION OF VARIATION AND THE NATURE OF SUBSTANTIVE FACTORS We have now seen that among the normal physiological processes the phenomena of division form a recognisable, and in all likelihood a naturally distinct group. Variations in these respects may thus be regarded as constituting a special class among variations in general. The substantive variations have only one property in common--the negative one that they are not Meristic. The work of classifying them and distinguishing them according to their several types demands a knowledge of the chemistry of life far higher than that to which science has yet attained. In reference to some of the simplest variations Garrod has introduced the appropriate term "Chemical sports." The condition in man known as Alkaptonuria in which the urine is red is due especially to the absence of the enzyme which decomposes the excretory substance, alkapton. The "chemical sport" here consists in the inability to break up the benzene ring. The chemical feature which distinguishes and is the proximate cause of several colour-varieties can now in a few cases be declared. The work of Miss Wheldale has shown that colour-varieties may be produced by the absence of the chromogen compound the oxidation of which gives rise to sap-colours, by differences in the completeness of this process of oxidation, and by a process of reduction supervening on or perhaps suppressing the oxidation. Some of these processes moreover may be brought about by the combined action of two bodies, the one an enzyme, for example an oxygenase, and the other a substance regarded as a peroxide, contributing the oxygen necessary for the oxidation to take place. Variation in colour may thus be brought about by the addition or omission of any one of the bodies concerned in the action. Similar variations, or rather similar series of variations will undoubtedly hereafter be identified in reference to all the various kinds of chemical processes upon which the structure and functions of living things depend. The identification of these processes and of the bodies concerned in them will lead to a real classification of Substantive Variations. To forecast the lines on which such classification will proceed is to look too far ahead. We may nevertheless anticipate with some confidence that future analysis will recognise among the contributing elements, some which are intrinsic and inalienable, and others which are extrinsic and superadded. We already know that there may be such interdependence among the substantive characters that to disentangle them will be a work of extreme difficulty. The mere fact that in our estimation characters belong to distinct physiological systems is no proof of their actual independence. In illustration may be mentioned the sap-colour in Stocks and the development of hoariness on the leaves and stems, which Miss Saunders's experiments have shown to be intimately connected, so that in certain varieties no hoariness is produced unless the elements for sap-colour are already present in the individual plant. The first step in the classification of substantive variations is therefore to determine which are due to the addition of new elements or factors, and which are produced by the omission of old ones. _A priori_ there is no valid criterion by which this can be known, and actual experiments in analytical breeding can alone provide the knowledge required. Some very curious results have by this method been obtained, which throw an altogether unexpected light on these problems. For example, in order that the remarkable development of mesoblastic black pigment characteristic of the Silky Fowl should be developed, it is practically certain that two distinct variations from such a type as _Gallus bankiva_ must have occurred. I assume, as is reasonable, that _G. bankiva_ has genetic properties similar to those of the Brown Leghorn breed which has been used in the experiments which Mr. Punnett and I have conducted. _Gallus bankiva_ was not available but the Brown Leghorn agrees with it very closely in colouration, and probably in the general physiology of its pigmentation. Setting aside the various structural differences between the two breeds, the Silky is immediately distinguished from the Leghorn by the fact that the skin of the whole body including that of the face and comb appears to be of a deep purplish colour. The face and comb of the Leghorn are red and the skin of the body is whitish yellow. On examination it is found that the purple colour of the Silky is in reality due to the distribution of a deep black pigment in the mesoblastic membranes throughout the body. The somatopleura, the pleura, _pia mater_, the dermis, and in most organs the connective tissue and the sheaths of the blood-vessels, are thus impregnated with black. No such pigmentation exists in the Leghorn. As the result of an elaborate series of experimental matings we have proved that the distinction between the Leghorn and the Silky consists primarily in the fact that the Silky possesses a pigment-producing factor, _P_, which is not present in the Leghorn. This variation must undoubtedly have been one of _addition_. But besides this there is another difference of an altogether dissimilar nature; for the Brown Leghorn possesses a factor which has the power of partially or completely restricting the operation of the pigment-producing factor, _P_. Moreover in respect of this pigment-restricting factor which we may call _D_, the sexes of the Brown Leghorn differ, for the male is homozygous or _DD_, but the female is heterozygous, _Dd_. Thus in order that the black-skinned breed could be evolved from such a type as a Brown Leghorn it must be necessary _both_ that _P_ should be added and that _D_ should drop out. We have not the faintest conception of the process by which either of these events have come to pass, but there is no reasonable doubt that in the evolution of the Silky fowl they did actually happen. We may anticipate that numerous interdependences of this kind will be discovered. Before any indisputable progress can be made with the problem of evolution it is necessary that we should acquire some real knowledge of the genesis of that class of phenomena which formed the subject of the last chapter. So long as the process of division remains entirely mysterious we can form no conception even of the haziest sort as to the nature of living organisms, or of the proximate causes which determine their forms, still less can we attempt any answer to those remoter questions of origin and destiny which form the subject of the philosopher's contemplation. It is in no spirit of dogmatism that I have ventured to indicate the direction in which I look for a solution, though I have none to offer. It may well be that before any solution is attained, our knowledge of the nature of unorganised matter must first be increased. For a long time yet we may have to halt, but we none the less do well to prepare ourselves to utilise any means of advance that may be offered, by carefully reconnoitering the ground we have to traverse. The real difficulty which blocks our progress is ignorance of the nature of division, or to use the more general term, of repetition. Let us turn to the more familiar problem of the causes of variation. Now since variation consists as much in meristic change as in alteration in substance or material, there is one great range of problems of causation from which we are as yet entirely cut off. We know nothing of the causation of division, and we have scarcely an observation, experiment or surmise touching the causes by which the meristic processes may be altered. Of the way in which variations in the substantive composition of organisms are caused we have almost as little real evidence, but we are beginning to know in what such variations must consist. These changes must occur either by the addition or loss of factors. We must not lose sight of the fact that though the factors operate by the production of enzymes, of bodies on which these enzymes can act, and of intermediary substances necessary to complete the enzyme-action, yet these bodies themselves can scarcely be themselves genetic factors, but consequences of their existence. What then are the factors themselves? Whence do they come? How do they become integral parts of the organism? Whence, for example, came the power which is present in a White Leghorn of destroying--probably reducing--the pigment in its feathers? That power is now a definite possession of the breed, present in all its germ-cells, male and female, taking part in their symmetrical divisions, and passed on equally to all as much as is the protoplasm or any other attribute of the breed. From the body of the bird the critical and efficient substance could in all likelihood be isolated by suitable means, just as the glycogen of the liver can be. But even when this extraction has been accomplished and the reducing body isolated, we shall know no more than we did before respecting the mode by which the power to produce it was conferred on the fowl, any more than we know how the walls of its blood-vessels acquired the power to form a fibrin-ferment. It is when the scope of such considerations as this are fully grasped that we realise the fatuousness of the conventional treatment which the problem of the causes of variation commonly receives. Environmental change, chemical injury, differences in food supply, in temperature, in moisture, or the like have been proposed as "causes." Admitting as we must do, that changes may be produced--usually inhibitions of development--by subjecting living things to changes in these respects, how can we suppose it in the smallest degree likely that very precise, new, and adaptative powers can be conferred on the germs by such treatment? Reports of positive genetic consequences observed comparable with those I have mentioned, become from time to time current. We should I think regard them with the gravest doubt. Few, so far as I am aware, have ever been confirmed, though clear and repeated confirmation should be demanded before we suffer ourselves at all to build upon such evidence. In a subsequent chapter some of these cases will be considered in detail. In no class of cases would the transmission of an acquired character superficially appear so probable as in those where power of resisting the attack of a pathogenic organism is acquired in the lifetime of the zygote. The possession of such a power is moreover a distinction comparable with those which differentiate varieties and species. It is due to the development in the blood of specific substances which pervade the whole fluid. This development is exactly one of those "appropriate responses to stimuli" which naturalists who incline to regard adaptation as a direct consequence of an environmental influence might most readily invoke as an illustration of their views. And yet all evidence is definitely unfavourable to the suggestion of an inheritance of the acquired power of resistance. Such change as can be perceived in the virulence of the attacks on successive generations may be most easily regarded as due to the extermination of the more susceptible strains, and perhaps in some measure to variation in the invading organisms themselves, an "acquired character" of quite different import. The specific "anti-body" may have been produced in response to the stimulus of disease, but the power to produce it without this special stimulus is not included in the germ-cells any more than a pigment. All that they bear is the _power to produce_ the anti-bodies when the stimulus is applied. If we could conceive of an organism like one of those to which disease may be due becoming actually incorporated with the system of its host, so as to form a constituent of its germ-cells and to take part in the symmetry of their divisions, we should have something analogous to the case of a species which acquires a new factor and emits a dominant variety. When we see the phenomenon in this light we realise the obscurity of the problem. The appearance of recessive varieties is comparatively easy to understand. All that is implied is the omission of a constituent. How precisely the omission is effected we cannot suggest, but it is not very difficult to suppose that by some mechanical fault of cell-division a power may be lost. Such variation by unpacking, or analysis of a previously existing complex, though unaccountable, is not inconceivable. But whence come the new dominants? Whether we imagine that they are created by some rearrangement or other change internal to the organism, or whether we try to conceive them as due to the assumption of something from without we are confronted by equally hopeless difficulty. The mystery of the origin of a dominant increases when it is realised that there is scarcely any recent and authentic account of such an event occurring under critical observation, which can be taken as a basis for discussion. The literature of horticulture for example abounds in cases alleged, but I do not think anyone can produce an illustration quite free from doubt. Such evidence is usually open to the suspicion that the plant was either introduced by some accident, or that it arose from a cross with a pre-existing dominant, or that it owed its origin to the meeting of complementary factors. In medical literature almost alone however, there are numerous records of the spontaneous origin of various abnormal conditions in man which habitually behave as dominants, and of the authenticity of some of these there can be no doubt. When we know that such conditions as hereditary cataract or various deformities of the fingers behave as dominants, we recognize that those conditions must be due to the addition of some element to the constitution of the normal man. In the collections of pedigrees relating to such pathological dominants there are usually to be found alleged instances of the origin of the condition _de novo_. Not only do these records occur with such frequency that they cannot be readily set aside as errors, but from general considerations it must be obvious that as these malformations are not common to normal humanity they must at some moment of time have been introduced. The lay reader may not be so much impressed with the difficulty as we are. He is accustomed to regard the origin of _any_ new character as equally mysterious, but when once dominants are distinguished from recessives the problem wears a new aspect. Thus the appearance of high artistic gifts, whether as an attribute of a race or as a sporadic event among the children of parents destitute of such faculties, is not very surprising, for we feel fairly sure that the faculty is a recessive, due to the loss of a controlling or inhibiting factor; but the _de novo_ origin of brachydactylous fingers in a child of normal parents is of quite a different nature, and must indicate the action of some new specific cause. Whether such evidence is applicable to the general problem of evolution may with some plausibility be questioned; but there is an obvious significance in the fact that it is among these pathological occurrences that we meet with phenomena most nearly resembling the spontaneous origin of dominant factors, and I cannot see such pedigrees as these without recalling Virchow's aphorism that every variation owes its origin to some pathological accident. In the evolution of domestic poultry, if _Gallus bankiva_ be indeed the parent form of all our breeds, at least some half dozen new factors must have been added during the process. In _bankiva_ there is, for example, no factor for rose comb, pea comb, barring on the feathers, or for the various dominant types of dark plumage. Whence came all these? It is, I think, by no means impossible that some other wild species now extinct did take part in the constitution of domestic poultry. It seems indeed to me improbable that the heavy breeds descend from _bankiva_. Both in regard to domestic races of fowls, pigeons, and some other forms, the belief in origin within the period of human civilization from one simple primitive wild type seems on a balance of probabilities insecurely founded, but allowing something for multiplicity of origin we still fall far short of the requisite total of factors. Elements exist in our domesticated breeds which we may feel with confidence have come in since their captivity began. Such elements in fowls are dominant whiteness, extra toe, feathered leg, frizzling, etc., so that even hypothetical extension of the range of origin is only a slight alleviation of the difficulty. Somehow or other, therefore, we must recognize that dominant factors do arise. Whether they are created by internal change, or whether, as seems to me not wholly beyond possibility, they obtain entrance from without, there is no evidence to show. If they were proved to enter from without, like pathogenic organisms, we should have to account for the extraordinary fact that they are distributed with fair constancy to half the gametes of the heterozygote. In proportion as the nature of dominants grows more clear so does it become increasingly difficult to make any plausible suggestion as to their possible derivation. On the other hand the origin of a recessive variety by the loss of a factor is a process so readily imagined that our wonder is rather that the phenomenon is not observed far more often. Some slip in the accurate working of the mechanical process of division, and a factor gets left out, the loss being attested by the appearance of a recessive variety in some subsequent generation. Consistently with this presentation of the facts we find that, as in our domesticated animals and plants, a diversity of recessives may appear within a moderately short period, and that when variations come they often do not come alone. Witness the cultural history of the Sweet Pea, _Primula Sinensis_, _Primula obconica_, _Nemesia strumosa_ and many such examples in which variation when it did come was abundant. The fact cannot be too often emphasized that in the vast proportion of these examples of substantive variation under domestication, as well as of substantive variation in the natural state, the change has come about by omission, not by addition. To take, for example, the case of the Potato, in which so many spontaneous bud-variations have been recorded, East after a careful study of the evidence has lately declared his belief that all are of this nature, and the opinion might be extended to many other groups of cases whether of bud or seminal variation. Morgan draws the same conclusion in reference to the many varieties he has studied in _Drosophila_. In the Sweet Pea, a form which is beyond suspicion of having been crossed with anything else, and has certainly produced all the multitude of types which we now possess by variations from one wild species, there is only one character of the modern types which could, with any plausibility, be referred to a factor not originally forming part of the constituents of the wild species. This is the waved edge, so characteristic of the "Spencer" varieties; for the cross between a smooth-edged and a waved type gives an intermediate not unfrequently. Nevertheless there is practically no doubt that this is merely an imperfection in the dominance of the smooth edge, and we may feel sure that any plant homozygous for smooth edge would show no wave at all. Hence it is quite possible that even the appearance of the original waved type, Countess Spencer, was due to the loss of one of the factors for smooth edge at some time in the history of the Sweet Pea. In the case of the Chinese Primrose (_Primula Sinensis_) one dominant factor has been introduced in modern times, probably within the last six years at most. This is the factor which causes suppression of the yellow eye, giving rise to the curious type known as "Queen Alexandra." Mr. R. P. Gregory's experiments proved that this was a very definite dominant, and the element responsible for this development is undoubtedly an addition to the original ingredient-properties, with which the species was endowed. Unfortunately, as happens in almost every case of the kind, the origin of this important novelty appears to be lost. Its behaviour, however, when crossed with various other types is that of a simple dominant giving an ordinary 3:1 ratio. There is therefore no real doubt that it came into existence by the definite addition of a new factor, for if it was simply a case of the appearance of a new character made by combination of two previously existing complementary factors we should expect that when Queen Alexandra was self-fertilised a 9:7 ratio would be a fairly common result, which is not in practice found. In _Oenothera_ Gates[1] has observed the appearance, in a large sowing of about 1,000 _Oenothera rubrinervis_, of a single individual having considerably more red pigment in the calyx than is usual in _rubrinervis_. The whole of the hypanthium in the flowers of this plant was red instead of green as in _rubrinervis_, and the whole of the sepals were red in the bud-stage, except for small green areas at the base. This type behaved as a dominant over _rubrinervis_, but so far a pure-breeding individual was not found. Admittedly the variation of this plant from the type of _rubrinervis_ can be represented as one of degree, though there is a very sensible gap in the series between the new form which Gates names "_rubricalyx_" and the reddest _rubrinervis_ seen in his cultures. It must certainly be recognised as a new dominant. Gates, rightly as I consider, regards the distinction between _rubrinervis_ and _rubricalyx_ as a quantitative one, and the same remark applies to certain other types differing in the amount of anthocyanin which they produce. I do not understand the argument which Gates introduces to the effect that the difference between such quantitative types cannot be represented in terms of presence and absence. We are quite accustomed to the fact that in the rabbit self-colour segregates from the Dutch-marked type. These two types differ in a manner which we may reasonably regard as quantitative. It is no doubt possible that the self-coloured type contains an ingredient which enables the colour to spread over the whole body, but it is, I think, perhaps more easy to regard the Dutch type as a form from which a part of the colour is absent. It may be spoken of in terms I have used, as a _subtraction-stage_ in colour. Following a similar method we may regard _rubricalyx_ as an addition-stage in colour-variation. The fact that crosses between _rubrinervis_, or _rubricalyx_ and _Lamarckiana_ give a mixture of types in F_{1}, does not I think show, as Gates declares, that there is any system here at work to which a factorial or Mendelian analysis does not apply; but that question may be more fitly discussed in connexion with the other problems raised by the behaviour of _Oenothera_ species in their crosses. I do, however, feel that, interesting as this case must be admitted to be, we cannot quite satisfactorily discuss it as an illustration of the _de novo_ origin of a dominant factor. The difference between the novelty and the type is quantitative, and it is not unreasonable to think of such a difference being brought about by some "pathological accident" in a cell-division. Recognition of the distinction between dominant and recessive characters has, it must be conceded, created a very serious obstacle in the way of any rational and concrete theory of evolution. While variations of all kinds could be regarded as manifestations of some mysterious instability of organisms this difficulty did not occur to the mind of evolutionists. To most of those who have taken part in genetic analysis it has become a permanent and continual obsession. With regard to the origin of recessive variations, there is, as we have seen, no special difficulty. They are negative and are due to absences, but as soon as it is understood that dominants are caused by an addition we are completely at a loss to account for their origin, for we cannot surmise any source from which they may have been derived. Just as when typhoid fever breaks out in his district the medical officer of health knows for certain that the bacillus of typhoid fever has by some means been brought into that district so do we know that when first dominant white fowls arose in the evolution of the domestic breeds, by some means the factor for dominant whiteness got into a bird, or into at least one of its germ-cells. Whence it came we cannot surmise. Whether we look to the outer world or to some rearrangement within the organism itself, the prospect of finding a source of such new elements is equally hopeless. Leaving this fundamental question aside as one which it is as yet quite unprofitable to discuss, we are on safe ground in foreseeing that the future classification of substantive variations, which genetic research must before long make possible, will be based on a reference to the modes of action of the several factors. Some will be seen to produce their effects by oxidation, some by reduction, some by generating substances of various types, sugars, enzymes, activators, and so forth. It may thus be anticipated that the relation of varieties to each other and to types from which they are derived will be expressible in terms of definite synthetical formulae. Clearly it will not for an indefinite time be possible to do this in practice for more than a few species and for characters especially amenable to experimental tests, but as soon as the applicability of such treatment is generally understood the influence on systematics must be immediate and profound, for the nature of the problem will at length be clear and, though the ideal may be unattainable, its significance cannot be gainsaid. * * * * * _Note._--With hesitation I allow this chapter to appear in the form in which it was printed a year ago, but in passing it for the press after that interval I feel it necessary to call attention to a possible line of argument not hitherto introduced. In all our discussions we have felt justified in declaring that the dominance of any character indicates that some factor is present which is responsible for the production of that character. Where there is no definite dominance and the heterozygote is of an intermediate nature we should be unable to declare on which side the factor concerned was present and from which side it was absent. The degree of dominance becomes thus the deciding criterion by which we distinguish the existence of factors. But it should be clearly realized that in any given case the argument can with perfect logic be inverted. We already recognize cases in which by the presence of an inhibiting factor a character may be suppressed and purely as a matter of symbolical expression we might apply the same conception of inhibition to any example of factorial influence whatever. For instance we say that in as much as two normal persons do not have brachydactylous children, there must be some factor in these abnormal persons which causes the modification. Our conclusion is based on the observed fact that the modification is a dominant. But it may be that normal persons are homozygous in respect of some factor _N_, which prevents the appearance of brachydactyly, and that in any one heterozygous, _Nn_, for this inhibiting factor, brachydactyly can appear. Similarly the round pea we say contains _R_, a factor which confers this property of roundness, without which its seeds would be wrinkled. But here we know that the wrinkled seed is in reality one having compound starch-grains, and that the heterozygote, though outwardly round enough, is intermediate in that starch-character. If we chose to say that the compoundness of the grains is due to a factor _C_ and that two doses of it are needed to make the seed wrinkled, I know no evidence by which such a thesis could be actually refuted. That such reasoning is seemingly perverse must be conceded; but when we consider the extraordinary difficulties which beset any attempt to conceive the mode of origin of a new dominant factor, we are bound to remember that there is this other line of argument which avoids that difficulty altogether. In the case of the "Alexandra"-eye in _Primula_, or the red calyx in Gates's _Oenothera_, inverting the reasoning adopted in the text, we may see that only the _Primula_ homozygous for the yellow eye can develop it and that two doses of the factor for the _rubrinervis_ calyx are required to prevent that part of the plant from being red. We may proceed further and extend this mode of reasoning to all cases of genetic variation, and thus conceive of all alike as due to loss of factors present in the original complex. Until we can recognize factors by means more direct than are provided by a perception of their effects, this doubt cannot be positively removed. For all practical purposes of symbolic expression we may still continue to use in our analyses the modes of representation hitherto adopted, but we must not, merely on the ground of its apparent perversity, refuse to admit that the line of argument here indicated may some day prove sound. FOOTNOTES: [1] Gates, R. R., _Zts. f. Abstammungslehre_, 1911, IV, pp. 341 and 361. CHAPTER V THE MUTATION THEORY When with the thoughts suggested in the last chapter we contemplate the problem of Evolution at large the hope at the present time of constructing even a mental picture of that process grows weak almost to the point of vanishing. We are left wondering that so lately men in general, whether scientific or lay, were so easily satisfied. Our satisfaction, as we now see, was chiefly founded on ignorance. Every specific evolutionary change must represent a definite event in the construction of the living complex. That event may be a disturbance in the meristic system, showing itself in a change in the frequency of the repetitions or in the distribution of differentiation among them, or again it may be a chemical change, adding or removing some factor from the sum total. If an attempt be made to apply these conceptions to an actual series of allied species the complexity of the problem is such that the mind is appalled. Ideas which in the abstract are apprehended and accepted with facility fade away before the concrete case. It is easy to imagine how Man was evolved from an _Amoeba_, but we cannot form a plausible guess as to how _Veronica agrestis_ and _Veronica polita_ were evolved, either one from the other, or both from a common form. We have not even an inkling of the steps by which a Silver Wyandotte fowl descended from _Gallus Bankiva_, and we can scarcely even believe that it did. The Wyandotte has its enormous size, its rose comb, its silver lacing, its tame spirit, and its high egg production. The tameness and the high egg production are probably enough both recessives, and though we cannot guess how the corresponding dominant factors have got lost, it is not very difficult to imagine that they were lost somehow. But the rose comb and the silver colour are _dominants_. The heavy weight also appears in the crosses with Leghorns, but we need not at once conclude that it depends on a simple dominant factor, because the big size of the crosses may be a consequence of the cross and may depend on other elements. Now no wild fowl known to us has these qualities. May we suppose that some extinct wild species had them? If so, may we again make the same supposition in all similar cases? To do so is little gain, for we are left with the further problem, whence did those lost wild species acquire those dominants? Suppositions of this kind help no more than did the once famous conjecture as to the origin of living things--that perhaps they came to earth on a meteorite. The unpacking of an original complex, the loss of various elements, and the recombination of pre-existing materials may all be invoked as sources of specific diversity. Undoubtedly the range of possibilities thus opened up is large. It will even cover an immense number of actual examples which in practice pass as illustrations of specific distinction. The Indian Rock pigeon which has a blue rump may quite reasonably be regarded as a geographically separated recessive form of our own _Columba livia_, for as Staples-Browne has shown the white rump of _livia_ is due to a dominant factor. The various degrees to which the leaves of Indian Cottons are incised have, as Leake says, been freely used as a means of classification. The diversities thus caused are very remarkable, and when taken together with diversities in habit, whether sympodial or monopodial, the various combinations of points of difference are sufficiently distinctive to justify any botanist in making a considerable number of species by reference to them alone. Nevertheless Leake's work goes far to prove that all of these forms represent the re-combinations of a very small number of factors. The classical example of _Primula Sinensis_ and its multiform races is in fact for a long way a true guide as to the actual interrelations of the species which systematists have made. That they did make them was due to no mistake in judgment or in principle, but simply to the want of that extended knowledge of the physiological nature of the specific cases which we now know to be a prime necessity. But will such analysis cover all or even most of the ordinary cases of specific diversity between near allies? Postponing the problem of the interrelations of the larger divisions as altogether beyond present comprehension, can we suppose, that in general, closely allied species and varieties represent the various consequences of the presence or absence of allelomorphic factors in their several combinations? The difficulty in making a positive answer lies in the fact that in most of the examples in which it has been possible to institute breeding experiments with a view to testing the question, a greater or less sterility is encountered. Where, however, no such sterility is met with, as for instance in the crosses made by E. Baur among the species of _Antirrhinum_ there is every reason to think that the whole mass of differences can and will eventually be expressed in terms of ordinary Mendelian factors. Baur has for example crossed species so unlike as _Antirrhinum majus_ and _molle_, forms differing from each other in almost every feature of organisation.[1] The F_{2} generation from this cross presents an amazingly motley array of types which might easily if met with in nature be described as many distinct species. Yet all are fertile and there is not the slightest difficulty in believing that they can all be reduced to terms of factorial analysis. If allowance be made for the complicating effects of sterility, is there anything which prevents us from supposing that such good species as those of _Veronica_ or of any other genus comprising well-defined forms may not be similarly related? I do not know any reason which can be pointed to as finally excluding such a possibility. Nevertheless it has been urged with some plausibility that good species are distinguished by _groups_ of differentiating characters, whereas if they were really related as the terms of a Mendelian F_{2} family are, we should expect to find not groups of characters in association, but rather series of forms corresponding to the presence and absence of the integral factors composing the groups of characters. I am not well enough versed in systematic work to be able to decide with confidence how much weight should be attached to this consideration. Some weight it certainly has, but I cannot yet regard it as forming a fatal objection to the application of factorial conceptions on the grand scale. It may be recalled that we are no longer under any difficulty in supposing that differences of all classes may be caused by the presence or absence of factors. It seemed at first for example that such characters as those of leaf shape might be too subtle and complex to be reducible to a limited number of factors. But first the work of Gregory on _Primula Sinensis_ showed that several very distinct types of leaves were related to each other in the simplest way. In that particular example, intermediates are so rare as to be negligible, but subsequently Shull dealing with such a complicated example as _Capsella_, and Leake in regard to Cottons, both forms in which intergrades occur in abundance, have shown that a simple factorial scheme is applicable. We need not therefore, to take an extreme case, doubt that if it were possible to examine the various forms of fruit seen in the Squashes by really comprehensive breeding tests, even this excessive polymorphism in respect of structural features would be similarly reducible to factorial order. It must always be remembered also that in a vast number of cases, nearly allied forms which are distinct, occupy distinct ground. Moreover, by whatever of the many available mechanisms that end be attained, it is clear that nature very often does succeed in preventing intercrossing between distinct forms so far that the occurrence of that phenomenon is a rarity under natural conditions. The facts may, I think, fairly be summarized in the statement that species are on the whole distinct and not intergrading, and that the distinctions between them are usually such as might be caused by the presence, absence, or inter-combination of groups of Mendelian factors; but that they are so caused the evidence is not yet sufficient to prove in more than a very few instances. The alternative, be it explicitly stated, is not to return to the view formerly so widely held, that the distinctions between species have arisen by the accumulation of minute or insensible differences. The further we proceed with our analyses the more inadequate and untenable does that conception of evolutionary change become. If the differences between species have not come about by the addition or loss of factors one at a time, then we must suppose that the changes have been effected by even larger steps, and variations including groups of characters, must be invoked. That changes of this latter order are really those by which species arise, is the view with which de Vries has now made us familiar by his writings on the Mutation Theory. In so far as mutations may consist in meristic changes of many kinds and in the loss of factors it is unnecessary to repeat that we have abundant evidence of their frequent occurrence. That they may also more rarely occur by the addition of a factor we are, I think, compelled to believe, though as yet the evidence is almost entirely circumstantial rather than direct. The evidence for the occurrence of those mutations of higher order, by which new species characterized by several distinct features are created, is far less strong, and after the best study of the records which I have been able to make, I find myself unconvinced. The facts alleged appear capable of other interpretations. The most famous and best studied examples are of course the forms of _Oenothera_ raised by de Vries from _Oenothera Lamarckiana_ in circumstances well known to all readers of genetic literature. Whatever be the true significance of these extraordinary "mutations" there can be no question about the great interest which attaches to them, and the historical importance which they will long preserve. Apart also from these considerations it is becoming more and more evident that in their peculiarities they provide illustrations of physiological phenomena of the highest consequence in the study of genetics at large. De Vries found, as is well known, that _Oenothera Lamarckiana_ gives off plants unlike itself. These mutational forms are of several distinct and recognizable types which recur, and several of them breed true from their first appearance. The obvious difficulty, which in my judgment should make us unwilling at present to accept these occurrences as proof of the genesis of new species by mutation, is that we have as yet no certainty that the appearance of the new forms is not an effect of the recombination of factors, such as is to be seen in so many generations of plants derived from a cross involving many genetic elements. The first question is what is _Oenothera Lamarckiana_? Is it itself a plant of hybrid origin? To this fundamental question no satisfactory answer has yet been given. All attempts to find it as a wild plant in America have failed. It existed in Europe in the latter half of the eighteenth century. Whence it came is still uncertain, but the view that it came into existence in Europe and perhaps in Paris, seems on the whole the most probable. The question has been debated by Macdougal, Gates, and Davis. From historical sources there is little expectation of further light. Those who favour the notion of a hybrid origin look on _Oenothera biennis_ as one of the putative parents. It has been conjectured that a species called _grandiflora_ lately re-discovered on the Alabama river was the other parent. Experiments have been instituted by Davis to discover whether _Lamarckiana_ can be made artificially by crossing these two species. The results so far have shown that while plants approximating in various respects to _Lamarckiana_ have thus been produced, none agree exactly with that form. Davis, to whom reference should be made for a full account of the present state of the enquiry, points out that there are many strains of _biennis_ in existence and that it is by no means impossible that by using others of these strains a still closer approximation can be made. None of Davis's artificial productions as yet breed at all true, as _Lamarckiana_ on the whole does. In such a case, however, where several characters are involved, this is perhaps hardly to be expected. One feature of the _Oenotheras_ is very curious. Not only _Lamarckiana_, but all the allied species so far as I am aware, have a considerable proportion of bad and shrivelled pollen grains. This is undoubtedly true of species living in the wild state as well as of those in cultivation. I have had opportunities of verifying this for myself in the United States. No one looking at the pollen of an _Oenothera_ would doubt that it was taken from some hybrid plant exhibiting partial sterility. On the other hand, it is difficult to suppose that numbers, perhaps all, of the "species" of the genus are really hybrids, and many of them breed substantially true. I regard this constant presence of bad pollen grains as an indication that the genetic physiology of _Oenothera_ is in some way abnormal, and as we shall presently see, there are several other signs which point in the same direction. Discussion of the whole series of phenomena is rendered exceedingly difficult first, by reason of the actual nature of the material. The characteristics of many of the types which de Vries has named are evasive. A few of these types, for instance, _gigas_, _nanella_, _albida_, _brevistylis_, and perhaps a few more are evidently clear enough, but we have as yet no figures and descriptions precise enough to enable a reader to appreciate exactly the peculiarities of the vast number of forms which have now to be considered in any attempt to gain a comprehensive view of the whole mass of facts. It is also not in dispute that the forms are susceptible of great variations due simply to soil and cultural influences. The fact that no Mendelian analysis has yet been found applicable to this group of _Oenotheras_ as a whole is perhaps largely due to the fact that until recently such analysis has not been seriously attempted. Following the system which he had adopted before the rediscovery of Mendelism, or at all events, before the development of that method of analysis, de Vries has freely applied _names_ to special combinations of characters and has scarcely ever instituted a factorial analysis. Before we can get much further this must be attempted. It may fail, but we must know exactly where and how this failure comes about. There are several indications that such a recognition of factorial characters, could be carried some way. For example, the height, the size of the flowers, the crinkling of the leaves, the brittleness of the stems, perhaps even the red stripes on stems and fruits, and many more, are all characters which may or may not depend on distinct factors, but if such characters are really transmitted in unresolved groups, the limitations of those groups should be carefully determined. The free use of names for the several forms, rather than for the characters, has greatly contributed to deepen the obscurity which veils the whole subject. I do not mean to suggest that these _Oenotheras_ follow a simple Mendelian system. All that we know of them goes to show that there are curious complications involved. One of these, probably the most important of all, has lately been recognized by de Vries himself, namely, that in certain types the characters borne by the female and the male germ-cells of the same plant are demonstrably different. There can be little doubt that further research will reveal cognate phenomena in many unsuspected places. The first example in which such a state of things was proved to exist is that of the Stocks investigated by Miss Saunders.[2] By a long course of analysis she succeeded in establishing in 1908 the fact that if a plant of _Matthiola_ is of that eversporting kind which gives a large proportion of double-flowered plants among its offspring (produced by self-fertilisation), then the egg-cells of such a plant are mixed in type, but the pollen of the same plant is homogeneous. Some of the egg-cells have in them the two factors for singleness, but some of them are short of one or both of these factors. The pollen-grains, however, are all recessives, containing neither of these factors. The egg-cells, in other words, are mixed, "singles" and "doubles," while the pollen-grains are all "doubles." The same is true of the factor differentiating "white," or colourless plastids from cream-coloured plastids in _Matthiola_, the egg-cells being mixed "whites" and "creams," while the pollen-grains are all "creams," viz: recessives. Later in the same year (1908) de Vries[3] announced a remarkable case which will be discussed in detail subsequently. It relates to certain _Oenotheras_ heterozygous for dwarfness, in which (p. 113) the ovules were mixed, tails and dwarfs, while the pollen is all dwarf. Again in _Petunia_ Miss Saunders's[4] work has shown that a somewhat similar state of things exists, but with this remarkable difference, that though the egg-cells are mixed, singles and doubles, the pollen-grains are all _singles_, viz: dominants. All the _Petunias_ yet examined have been in this condition, including some which in botanic gardens pass for original species. Whether actual wild plants from their native habitats are in the same state, is not yet known, but it is by no means improbable. The case may be compared with that of the moth _Abraxas grossulariata_ studied by Doncaster and Raynor, in which the females are all heterozygous, or we may almost say "hybrids" of _grossulariata_ and the variety _lacticolor_. Similarly we may say that at least garden Petunias are heterozygous in respect of singleness. The proof of this is of course that when fertilised with the pollen of doubles they throw a mixture of doubles and singles. The statements which de Vries has published regarding the behaviour of several of the _Oenotheras_ go far to show that they must have a somewhat similar organisation. On the present evidence it is still quite impossible to construct a coherent scheme which will represent all the phenomena in their interrelations, and among the facts are several which, as will appear, seem mutually incompatible. The first indication that the _Oenotheras_ may have either mixed ovules or mixed pollen appears in the fact that _Lamarckiana_ and several of its "mutants" used as males, with several other forms as females, give a mixed offspring. For example, de Vries (1907) found that _biennis_ [F] � _Lamarckiana_ [M] _biennis cruciata_ [F] � _Lamarckiana_ [M] _muricata_ [F] � _Lamarckiana_ [M] _biennis_ [F] � _rubrinervis_ [M] _biennis cruciata_ [F] � _rubrinervis_ [M] all give a mixture of two distinct types which he names _laeta_ and _velutina_, consisting of about equal numbers of each. On account of the fact that the two forms are produced in association de Vries has called these forms "twin hybrids," a designation which is not fortunate, seeing that it is impossible to imagine that any kind of twinning is concerned in their production. The distinction between these two seems to be considerable, _laeta_ having leaves broader, bright green in colour, and flat, with pollen scanty, while _velutina_ has leaves narrower, grayish green, more hairy, and furrow-shaped, with pollen abundant. We next meet the remarkable fact that these two forms, _laeta_ and _velutina_ breed true to their respective types, and do not reproduce the parent-types among their offspring resulting from self-fertilisation. This statement must be qualified in two respects. When _muricata_ [M] is fertilised by _brevistylis_ the forms _laeta_ and _velutina_ are produced, but each of them subsequently throws the short-styled form as a recessive (de Vries, 1907, p. 406). It may be remembered that de Vries's previous publications had already shown that the short style of _brevistylis_, one of the _Lamarckiana_ "mutants," behaves as a recessive habitually (_Mutationstheorie_, II, p. 178, etc.). Also when _nanella_, the dwarf "mutant" of _Lamarckiana_ is used as male on _muricata_ as female, _laeta_ and _velutina_ are produced, but one only of these, namely, _velutina_, subsequently throws dwarfs on self-fertilisation. The dwarfs thus thrown are said to form about 50 per cent. of the families in which they occur (de Vries, 1908, p. 668). The fact that the two forms, _laeta_ and _velutina_, are produced by many matings in which _Lamarckiana_ and its mutant _rubrinervis_ are used as males is confirmed abundantly by Honing, who has carried out extensive researches on the subject. After carefully reading his paper, I have failed to understand the main purport of the argument respecting the "double nature" of _Lamarckiana_ which he founds on these results, but I gather that in some way _laeta_ is shown to partake especially of the nature of _Lamarckiana_, while _velutina_ is a form of _rubrinervis_. The paper contains many records which will be of value in subsequent analysis of these forms. Before considering the possible meaning of these facts we must have in our minds the next and most novel of the recent extensions of knowledge as to the genetic properties of the _Oenotheras_. In the previous statement we have been concerned with the results of using either _Lamarckiana_ itself or one of its "mutants" _rubrinervis_, _brevistylis_, or _nanella_ as male, on one of the species _biennis_ or _muricata_. The new experiments relate to crosses between the two species _biennis_ and _muricata_ themselves. De Vries found: 1. That the reciprocal hybrids from these two species differed, _biennis_ � _muricata_ producing one type of F_{1} and _muricata_ � _biennis_ producing another. Each F_{1} resembled the father more than the mother. 2. That each of the hybrids so produced breeds true on self-fertilisation. 3. That if we speak of the hybrid from _biennis_ � _muricata_ as _BM_ and of the reciprocal as _MB_, then _BM_ � _MB_ gives exclusively offspring of _biennis_ type but that _MB_ � _BM_ gives exclusively offspring of _muricata_ type. Evidently, apart from all controversy as to the significance of the "mutants" of _Lamarckiana_, we have here a series of observations of the first importance. The fact that reciprocal crossings give constantly distinct results must be taken to indicate that the male and female sides of one, if not of both, of the parents are different in respect of characters which they bear. This is de Vries's view, and he concludes rightly, I think, that the evidence from all the experiments shows that both _biennis_ and _muricata_ are in this condition, having one set of characters represented in their pollen-grains and another in their ovules. The plants breed true, but their somatic structures are compounded of the two sets of elements which pass into them from their maternal and paternal sides respectively. This possibility that species may exist of which the males really belong to one form and the females to another, is one which it was evident from the first announcement of the discovery of Mendelian segregation might be found realised in nature.[5] _Oe. biennis_ and _muricata_ were crossed reciprocally with each other and with a number of other species, and the behaviour of each, when used as mother, was consistently different from its behaviour when used as father. De Vries is evidently justified by the results of this series of experiments in stating that the "Bild," as he terms it, or composition of the male and female sides of these two species, _biennis_ and _muricata_, are distinct. On the evidence before us it is not, however, possible to form a perfectly clear idea of each, and until details are published, a reader without personal knowledge of the material cannot do more than follow the general course of the argument. For fuller comprehension a proper analysis of the characters with a clear statement of how they are distributed among the several types and crosses is absolutely necessary. According to de Vries the female of _biennis_ possesses a group of characters which he defines as "_conica_" in allusion to the shape of the flower-buds. Besides the conical buds, this group of features includes imperfect development of wood, rendering the plant very liable to attacks of _Botrytis_, and comparatively narrow leaves. The female of _muricata_ carries a group of features which he calls "_frigida_," and, though this is not quite explicitly stated in a definition of that type, it is to be inferred[6] that its characteristics are regarded as greater height, strong development of wood with comparative resistance to _Botrytis_, and broad leaves. The characters borne by the male parts of the two species are in general those by which they are outwardly distinguished. For example, the leaves of _Oe. biennis_ are comparatively broad and are bright green, while those of _muricata_ are much narrower and of a glaucous green, and I understand that de Vries regards these properties as contributed by the male side in each case and to be carried by the male cells of each species. The suggestion as regards _biennis_ and _muricata_ comes near the conception often expressed by naturalists in former times (_e. g._, Linnaeus) and not rarely entertained by breeders at the present day, that the internal structure is contributed by the mother and the external by the father. On the other hand, the offspring of each species when used as mother is regarded as possessing in the main the features of the maternal "Bild," but the matter is naturally complicated by the introduction of features from the father's side, and it is here especially that the account provided is at present unsatisfactory and inconclusive. There seems, however, to be no serious doubt that _biennis_ and _muricata_ each in their outward appearance exhibit on the whole the features which their pollens respectively carry, and that the features borne by their ovules are in many respects distinct. The _types_ are thus "hybrids" which breed true. The results of intercrossing them each way are again "hybrids" which breed true. It will be remembered that on former occasions de Vries has formulated a general rule that _species_-hybrids breed true, but that the cross-breds raised by interbreeding _varieties_ do not. One of these very cases was quoted[7] as an illustration of this principle, viz: _muricata_ � _biennis_. The grounds for this general statement have always appeared to me insufficient, and with the further knowledge which the new evidence provides we are encouraged to hope that when a proper factorial analysis of the types is instituted we shall find that the phenomenon of a constant hybrid will be readily brought into line with the systems of descent already worked out for such cases as that of the Stocks, and others already mentioned. In further discussion of these facts de Vries makes a suggestion which seems to me improbable. Since the egg-cells of _muricata_, for instance, bear a certain group of features which are missing on the male side, and conversely the pollen bears features absent from the female side, he is inclined to regard the _bad pollen grains_ as the bearers of the missing elements of the male side and to infer that there must similarly be defective ovules representing the missing elements of the female side. No consideration is adduced in support of this view beyond the simple fact that the characters borne by male and female are dissimilar, whereas it would be more in accord with preconception if the same sets of combinations were represented in each--as in a normal Mendelian case. There is as yet no instance in which the absence of any particular class of gametes has been shown with any plausibility to be due to defective viability, though there are, of course, cases in which certain classes of zygotes do not survive owing to defective constitution (_e. g._, the albinos of _Antirrhinum_ studied by Baur, and the homozygous yellow mice). I am rather inclined to suppose that in these examples of hybrids breeding true we shall find a state of things comparable with that to which we formerly applied the terms "coupling" and "repulsion." In these cases certain of the possible combinations of factors occur in the gametic series with special frequency, being in excess, while the gametes representing other combinations are comparatively few. In a recent paper on these cases Professor Punnett and I have shown that these curious results vary according to the manner in which the factors are grouped in the parents. If _A_ and _B_ are two factors which exhibit these phenomena we find that the gametic series of the double heterozygote differs according as the combination is made by crossing _AB � ab_, or by crossing _AB � aB_. In a normal Mendelian case the F_{1} form, _AaBb_, produces gametes _AB_, _Ab_, _aB_, _ab_, in equal numbers; but in these peculiar cases those gametes which contain Gametic series Number of Number of --------------------- gametes zygotes AB Ab aB ab in series formed Partial repulsion { 1 (n-1) (n-1) 1 2n 4n^{2} from zygote { 1 31 31 1 64 4096 of form { 1 15 15 1 32 1024 Ab�aB { 1 7 7 1 16 256 { 1 3 3 1 8 64 1 1 1 1 4 16 Partial coupling { 3 1 1 3 8 64 from zygote { 7 1 1 7 16 256 of form { 15 1 1 15 32 1024 AB�ab { 31 1 1 31 64 4096 { 63 1 1 63 128 16384 { (n-1) 1 1 (n-1) 2n 4n^{2} Nature of zygotic series --------------------------------------- AB Ab aB ab Partial repulsion { 2n^{2}+1 n^{2}-1 n^{2}-1 1 from zygote { 2049 1023 1023 1 of form { 513 255 255 1 Ab�aB { 129 63 63 1 { 33 15 15 1 9 3 3 1 { 41 7 7 9 Partial coupling { 177 15 15 49 from zygote { 737 31 31 225 of form { 3009 63 63 961 AB�ab { 12161 127 127 3969 { 3n^{2}-(2n - 1) 2n-1 2n-1 n^{2}-(2n-1) the _parental combinations_ are in excess. This excess almost certainly follows the system indicated by the accompanying table. In the general expressions _n_ is half the number of gametes required to express the whole system. Now if we imagine that sex-factors are involved with the others concerned in such a relationship as this we have a system of distribution approximating to that found in _biennis_ and _muricata_. The difference in reciprocals is represented in a not improbable way. It cannot yet be said that the rarer terms in the series are formed at all, and perhaps they are not. As we pointed out in our discussion of these phenomena, the peculiar distribution of factors in these cases must be taken to mean that the planes of division at some critical stage in the segregation are determined with reference to the parental groups of factors, or in other words, that the whole system has a polarity, and that the distribution of factors with reference to this polarity differs according to the grouping of factors in the gametes which united in fertilization to produce the plant. Subsequent proliferation of cells representing certain combinations would then lead to excess of the gametes bearing them. It is on similar lines that I anticipate we shall hereafter find the interpretation of the curious facts discovered by de Vries, though it is evident that a long course of experiment and analysis must be carried through before any certainty is reached. The work must be begun by a careful study of the descent of some single factor, for example, that causing the broader leaf of _biennis_, and we may hope that the study of _Oenothera_ by proper analytical methods will no longer be deferred. We have now to return to the relations of _laeta_ and _velutina_. These two forms, it will be remembered are frequently produced when _Lamarckiana_ or one of its derivatives is used as male, and the most unexpected feature in their behaviour is that _both breed true as regards their essential characteristics, on self-fertilisation_. If one only bred true the case might, in view of the approximate numerical equality of the two types, be difficult to interpret on ordinary lines, but as both breed true it must be clear that some quite special system of segregation is at work. What this may be cannot be detected on the evidence, but with the results from the _biennis-muricata_ experiments before us, it is natural to suspect that we may here again have to recognise a process of allocation of different factors to the male and female sides in _laeta_ and _velutina_. That some such system is in operation becomes the more probable from the new fact which de Vries states in describing the group of characters which he calls _conica_, namely that this type is the same as that of _velutina_. There are many collateral observations recorded both by de Vries and others which have a bearing on the problems, but they do not yet fall into a coherent scheme. For example, we cannot yet represent the formation of _laeta_ and _velutina_ from the various species fertilised by _Lamarckiana_ [M]. That this is not due to any special property associated with the pollen of _Lamarckiana_ is shown by the fact that a species called _Hookeri_ gives _laeta_ and _velutina_ in both its reciprocal crosses with _Lamarckiana_ (de Vries, 1909, p. 3), and also by the similar fact that _Lamarckiana_ [F] fertilised by the pollen of a peculiar race of _biennis_ named _biennis Chicago_ throws the same types. Before these very complicated phenomena can be usefully discussed particulars must be provided as to the individuality of the various plants used. This criticism applies to much of the work which de Vries has lately published, for, as we now know familiarly, plants to which the same name applies can be quite different in genetic composition. Attention should also be called to one curiously paradoxical series of results. When the dwarf "mutant" of _Lamarckiana_ which de Vries names "_nanella_" is used as father on _muricata_, F_{1} consists of _laeta_ and _velutina_ in approximately equal numbers. Both forms breed true to their special characteristics, but _velutina_ throws dwarfs of its own type, while _laeta_ does not throw dwarfs. Subsequent investigation of the properties of these types has led to some remarkable conclusions, and it was in a study of these plants that de Vries first came upon the phenomena of dissimilarity between the factors borne by the male and female cells of the same plant, a condition which had been recently detected in the Stocks as a result of Miss Saunders's investigations. The details are very remarkable. We have first the fact that _muricata_ [F] � dwarf _nanella_ [M] gives about 50 per cent. _laeta_ and about 50 per cent. of _velutina_. As regards _Velutina_ it was shown that: Talls, Dwarfs, per cent. per cent. 1. Velutina selfed gave 38 62 {Velutina [F] � dwarf nanella [M] gave 39 61 2.{ do. � do. gave 49 51 { do. � dwarf [M] derived from velutina gave 43 57 3. Dwarfs � velutina [M] gave -- all dwarfs The three experiments taken together prove, as de Vries says, that the ovules of _velutina_ are mixed, talls and dwarfs, and that the pollen is all dwarf. The condition is almost the same as that of the Stocks. It may be noted also that in the Stocks the egg-cells of the "double" type are in excess, being approximately 9 to 7 of the "single" type, but de Vries regards the two types in _velutina_ as probably equal in number. The figures (169:231) rather suggest some excess of the recessives, perhaps 9:7, and the point would be worth a further investigation. As regards _laeta_, by self-fertilisation _no dwarfs were produced_, but in all other respects it behaved almost exactly like _velutina_. The ovules are evidently mixed talls and dwarfs, and whether fertilised by dwarfs or by the pollen of _velutina_, which is already proved to be all dwarf, the result was a steady 50 per cent. of talls and 50 per cent. of dwarfs. The pollen of _laeta_ used on dwarfs gives nothing but dwarfs, and in three series of such experiments 226 dwarfs were produced. We are thus faced with this difficulty. Since the egg-cells of _laeta_ are evidently mixed, talls and dwarfs, and the pollen used on dwarfs gives all dwarfs, why does not self-fertilisation give a mixed result, talls and dwarfs, instead of _all talls_? De Vries regards the result of self-fertilisation as showing the real nature of the pollen, and declares it to be all talls, while he represents the behaviour of the same pollen used on dwarfs by stating that in these combinations the dwarf character dominates. This does not seem to me a natural interpretation. I should regard the pollen of _laeta_ as identical with that of _velutina_, namely dwarf, and I suspect the difficulty is really created by the behaviour of _laeta_ on self-fertilisation. Until a proper analysis is made in which the identity of the different individuals used is recorded, no further discussion is possible.[8] Other results of a complicated kind involving production of _laeta_ and _velutina_ together with a third form have been published by de Vries in his paper on "Triple Hybrids." To these also the same criticism applies. Some of the observations seem capable of simple factorial representation and others are conflicting. Taking the work on _Oenothera_ as a whole we see in it continually glimpses of order which further on are still blocked by difficulties and apparent inconsistencies. Through such a stage all the successful researches in complicated factorial analysis have passed and I see no reason for supposing that with the application of more stringent methods this more difficult set of problems will be found incapable of similar solutions. To return to the original question whether in _Oenothera_ we can claim to see a special contemporaneous output of new species in actual process of creation, it will be obvious that while the interrelation of the several types is still so little understood, such a claim has no adequate support. It is true that many of the "mutants" of _Lamarckiana_ can well pass for species, but this is equally true of many new combinations of pre-existing factors as we have seen in _Primula Sinensis_ and other cases. Still less can it be admitted that these facts of uncertain import supply a justification for the conception which has played a prominent part in the scheme of the _Mutationstheorie_, namely that there are special periods of Mutation, when the parent-species has peculiar genetic properties. To conclude: The impression which the evidence leaves most definitely on the mind is that further discussion of the bearing which the _Oenotheras_ may have on the problem of evolution should be postponed until we have before us the results of a searching analysis applied to a limited part of the field. In such an analysis it is to be especially remembered that we have now a new clue in the well-ascertained fact that the genetic composition of the male and female germ-cells of the same individual may be quite different. When with this possibility in view the behaviour of the types is re-examined I anticipate that many of the difficulties will be removed. Outside the evidence from _Oenothera_, which, as we have seen, is still ambiguous, I know no considerable body of facts favourable to that special view of Mutation which de Vries has promulgated. Of variation, or if we will, Mutation, in respect of some one character, or resulting from recombination, there is proof in abundance; but of that simultaneous variation in several independent respects to which de Vries especially attributes the origin of new specific types I know only casual records which have yet to undergo the process of criticism. * * * * * Besides de Vries's "_Mutationstheorie_" and "Species and Varieties" the chief publications relating to the subject of the behaviour of _Oenothera_ are the following: (Many other papers relating especially to the cytology of the forms have appeared.) Davis, B. M. Genetical Studies on _Oenothera_, I. _Amer. Nat._, XLIV, 1910, p. 108. Genetical Studies on _Oenothera_, II. _Ibid._, XLV, 1911, p. 193. Gates, R. R. An Analytical Key to some of the Segregates of Oenothera. _Twentieth Annual Report of the Missouri Botanical Garden_, 1909. Studies on the Variability and Heritability of Pigmentation in _Oenothera_. _Ztsch. f. Abstammungslehre_, 1911, IV, p. 337. Honing, J. A. Die Doppelnatur der _Oenothera Lamarckiana_. _Ztsch. f. Abstammungslehre_, 1911, IV, p. 227. Macdougal, D. T. (with A. M. Vail, G. H. Shull, and J. K. Small). Mutants and Hybrids of the _Oenotheras_. _Carnegie Institution's Publication_, No. 24, 1905. Macdougal, D. T., Vail, A. M., Shull, J. H. Mutations, Variations and Relationships of the _Oenotheras_. _Carnegie Institution's Publication_, No. 81, 1907. de Vries, H. On Atavistic Variation in _Oenothera cruciata_. _Bull. Torrey Club_, 1903, Vol. 30, p. 75. On Twin Hybrids, _Bot. Gaz._, Vol. 44, 1907, p. 401. Ueber die Zwillingsbastarde von _Oenothera nanella_. _Ber. Deut. Bot. Ges._, 1908, XXVI, _a_, p. 667. Bastarde von _Oenothera gigas_. _Ibid._, p. 754. On Triple Hybrids. _Bot. Gaz._, 1909, Vol. 47, p. 1. Ueb. doppeltreziproke Bastarde von _Oenothera biennis_ L. und _Oenothera muricata_ L. _Biol. Cbltt._, 1911, XXXI, p. 97. Zeijlstra, H. H. _Oenothera nanella_ de Vries, eine krankhafte Pflanzenart. _Biol. Cbltt._, 1911, XXXI, p. 129. NOTE. Since this chapter was written two contributions of special importance have been made to the study of the _Oenothera_ problems. The first is that of Heribert-Nilsson.[9] The author begins by giving a critical account of the evidence for de Vries's interpretation of the nature of the mutants. In general this criticism pursues lines similar to those sketched in the foregoing chapter, concluding, as I have done, that the chief reason why factorial analysis has been declared to be inapplicable to the _Oenothera_ mutants is because no one has hitherto set about this analysis in the right way. He has also himself made a valuable beginning of such an analysis and gives good evidential reasons for the belief that at least the red veining depends on a definite factor which also influences the size of certain parts of the plant. He argues further that many of the distinctions between the mutants are quantitative in nature. With great plausibility he suggests that the system of cumulative factors which Nilsson-Ehle discovered in the case of wheat (subsequently traced by East in regard to maize) may be operating also in these _Oenotheras_. According to this system several factors having similar powers may coexist in the same individual, and together produce a cumulative effect. Scope would thus be given for the production of the curious and seemingly irregular numbers so often recorded in the "mutating" families. Another remarkable observation relating to the crosses of _muricata_ and _biennis_ has been published by Goldschmidt.[10] He finds that in the formation of this cross the female pronucleus takes no part in the development of the zygotic cell, but that when the male pronucleus enters, the female pronucleus is pushed aside and degenerates. As de Vries observed, the reciprocal hybrids are in each case very like the father ("_stark patroklin_"), a consequence which finds a natural explanation in the phenomenon witnessed by Goldschmidt. The results of the subsequent matings can also be readily interpreted on the same lines. Indications of maternal characters are nevertheless mentioned by de Vries, and if Goldschmidt's account of the cytology is confirmed, these must presumably be referred to the influence of the maternal cytoplasm. Clearly this new work opens up lines of exceptional interest. The interpretation I have offered above must probably be reconsidered. The distinction between the male and female cells of the types may no doubt be ultimately factorial, but it is difficult to regard such a distinction as created by a differential distribution of the ordinary factors. FOOTNOTES: [1] See Lotsy and Baur, Rep. Genetics Conf., Paris, 1911, pp. 416-426. Compare Lecoq on _Mirabilis jalapa_ � _longiflora_, Fécondation des Végétaux, 1862, p. 311. [2] _Rep. Evol. Ctee. R. S._, IV, 1908, p. 38. [3] _Ber. Deut. Bot. Ges._, 1908, XXVI, _a_, p. 672. [4] _Jour. Genetics_, 1, 1910, p. 57. [5] In Rep. 1 to Evol. Committee, 1902, p. 132, attention was called to this possibility, though of course at that date it was in sexual animals alone that it was supposed to exist. It had not occurred to me that even a hermaphrodite plant might be in this condition. [6] From the description of the offspring of _muricata_ used as mother. [7] de Vries, _Species and Varieties_, 1905, p. 259. [8] Zeijlstra in a recent paper announces that many _nanella_ plants are the subject of a bacterial disease to which he attributes their dwarfness. I gather that this does not apply to all _nanella_ plants and that some are dwarfs apart from disease. The matter may no doubt be further complicated from this cause. [9] _Zts. f. Abstamm._, 1912, VIII. [10] _Arch. f. Zellforschung_, 1912, IX, p. 331. CHAPTER VI VARIATION AND LOCALITY In all discussions of the modes of Evolution the phenomena of Geographical Distribution have been admitted to be of paramount importance. First came the broad question, were the facts of distribution consistent with the Doctrine of Descent? I suppose all naturalists are now agreed that they are thus consistent, and that though some very curious and as yet inexplicable cases remain to be accounted for, the distribution of animal and plant life on the face of the earth is much what we might expect as a result of a process of descent with modification. Passing from this general admission to the more particular question whether the facts of distribution favour one special conception of the mode of progress of evolution rather than another, no agreement has yet been reached. One outstanding feature is hardly in dispute, namely that prolonged isolation is generally followed by greater or less change in the population isolated. Groups of individuals which from various causes are debarred from free intermixture with other groups almost always exhibit peculiarities, but on the other hand, cosmopolitan types which range over wide areas are on the whole uniform, or nearly so throughout their distribution. Examples of these two categories will be familiar to all naturalists. The barriers to intercourse may be seas, deserts, prairies, mountain-chains, or circumstances of a much less obvious character which isolate quite as effectually. The local unit is not necessarily an island, a district, or an area of special geological formation, but may, as every collector knows, be a valley, a pond, a creek, a "bank" in the sea, a clump of trees, a group of rocks in a bay, or a particular patch of ground on a mountain side. All the great groups provide examples of such specially isolated forms. The botanist knows them well; the conchologist, the entomologist, the ornithologist and the student of marine life are all equally aware that special varieties or special species come from special places and from nowhere else. In one remarkable case the season of appearance plainly acts as the isolating barrier. _Tephrosia bistortata_ is a small Geometrid moth which has two broods, appearing in _March_ and _July_ respectively. It is closely allied to _T. crepuscularia_ which emerges in _May_ and _June_. From the fact that occasional specimens cannot be quite certainly referred to one or other of the two, many have held that the two are one species. Nevertheless, in general they present distinctions which are plain enough. Some localities have one form only, but in several woods they co-exist. Experiment has shown that the two can be crossed, and that the cross-breds can breed _inter se_ and with at least one of the parent stocks.[1] Some diminution in fertility was observed, but perhaps not more than is commonly encountered when wild forms are bred in captivity. In such a case it can scarcely be doubted that the distinctness of the two forms in the places where they co-exist is maintained by the seasonal isolation. Just as the consequences of isolation are to be seen in the most different forms of life so may they also affect the most diverse features of organisation, such as size, colour, sculpture, shape, or number of parts. In the Sloth (_Choloepus_) the geographical races differ in the number of cervical vertebrae--or in other words, in the distribution of vertebral differentiation. The geographical races of _Cistudo_ differ in the number of claws and phalanges.[2] In Shetland, the males of _Hepialus humuli_ (the Ghost Moth) are not sharply differentiated in colour from the females, as they are elsewhere, but in varying degrees resemble them.[3] No such males are found in other localities, and even in the other Scottish islands they are normal. In the island of Waigiu the converse phenomenon has been observed in _Phalanger maculatus_. Generally the male is spotted with white, and the female is without spots, but in Waigiu the females are spotted like the males.[4] The following striking illustration was pointed out to me by Dr. W. D. Miller. _Euphonia elegantissima_ as it occurs in Mexico and Central America has the two sexes very distinct from each other. The male has the lower parts orange and the upper parts a dark indigo blue, with a bright turquoise-blue head and neck. The female, except for the head, is of a bright olive green. A form in which the sexes are similarly differentiated exists in Porto Rico and is known as _E. Sclateri_. But in many of the other West Indian islands the representative "species" (_E. flavifrons_) has the two sexes closely resembling the _female_ of _E. elegantissima_. This form is found in Antigua, Barbados, St. Vincent, and Guadeloupe, from which localities the British Museum has specimens. All three so-called species are very much alike otherwise. In the genus _Pyrrhulagra_ (_Loxigilla_) to which Mr. Outram Bangs called my attention, several distinct and alternative possibilities occur. The genus has many local species occurring on the various West Indian islands. These species are characterized by differences in size, colour, and the shape of the bill. The colours have a narrow range, being black or greyish, with or without chestnut marks about the head and throat. In most of the islands the males are in general colour a full black, and the females are distinctly grey. They are thus found in San Domingo, Jamaica, Bahama, and most of the Lesser Antilles. In Porto Rico we meet the peculiarity that the hens are almost as black as the males (Ridgway describes the black of the hens as slightly less intense). This form is called _portoricensis_. A larger type, known as _grandis_, similarly coloured, inhabits St. Kitt's. Then, on the contrary, in Barbados, _both sexes_ are a dull blackish grey, like the hens of the Lesser Antilles in general. The local species of _Agelaius_ show similarly capricious distinctions. _A. phoeniceus_ is a widely spread species, found over a great part of North America. The male is black with red-orange bars on the wings, but the female is somewhat thrush-like in colour. In the island of Porto Rico there is a form called _xanthomus_, in which _both sexes_ are like the males of the mainland. A similar species called _humeralis_, also with both sexes male-like, lives in Cuba. The island of Cuba, curiously enough, has also a distinct species named _assimilis_, in which the female is a dull black all over, though the male is like the mainland type. So also may local races differ in respect of variability. _Argynnis paphia_, the Silver Washed Fritillary, through a great part of its distribution has only one female form. In the English New Forest a second female form, _valesina_, co-exists with the ordinary _paphia_ female. But in the southern valleys of the Alps the _valesina_ female is much the commoner of the two, and indeed in some localities where the species is abundant, I have seen no _paphia_ females in many days collecting. The beetle _Gonioctena variabilis_ furnishes an illustration of a comparable phenomenon affecting the male sex. In 1894 and 1895 I studied the curious colour variations of this species especially in the neighbourhood of Granada, and Mr. Doncaster ten years later repeated the observations on the same ground, and also collected the insect in other places in the south of Spain. The distinctions are not easy to give in words and the reader is referred to the colour plate accompanying my paper.[5] The essential fact is that the males commonly have the elytra _red with black spots_ and the females for the most part have greenish grey elytra with black stripes. In some localities a large minority of males closely resemble the female type, being identical in colour and then only distinguishable by structural differences. In two Granada localities I found the proportion of such males quite different. In the Darro valley about 38 per cent. (in 718) were of this feminine type, but on the hills some 300 feet above only 19 per cent. (in 3,230) were like the females. At Castillejo, not far from Toledo I found no such male in 75 specimens. Mr. Doncaster collected from several localities, especially from two areas near Malaga, about 5 miles apart. In one of these the female-like males were, as usual, in a minority, but in the other these were actually in great excess, amounting to about 81 per cent. in the 173 taken. Doncaster found a doubtful indication that the composition of the population varies with the season, which is quite possible, but it is most interesting to note that in my chief locality after the lapse of ten years he found the proportions very much the same as I had done at the same season, for where I had 19 per cent. of the female-like males his collecting gave 16 per cent. In other respects also, his statistics corresponded very closely with mine.[6] The various forms of _Heliconius erato_ are well known to entomologists. They are strikingly distinguished by the colours of the strong comb-like marking on the hind wing, which may be red, yellow, green or blue. In various parts of the distribution in South America sometimes two and sometimes three of these distinct types co-exist.[7] The distribution of the varieties of _Noctua castanea_ typifies a large range of cases. The form which is reckoned the normal of the species has red fore-wings. It is practically restricted to Great Britain and Germany, according to Tutt. The other common form, _neglecta_, has grey fore-wings, and in this pattern it ranges through West Central Europe from North Italy to Germany. In the British Isles it extends up to Orkney. In Britain this grey form is by far the commoner, occurring wherever the species is found. The red form is much scarcer in England, and does not occur at all in many localities where the grey form is common. Mr. Woodforde, from whom this account is taken,[8] states that in August, 1899, he saw considerably over a hundred of the grey in the New Forest at sugar, but only two red ones. In Staffordshire however the red is proportionately more numerous and he estimates them as 40 per cent. of the population. Lastly a form has been taken in Staffordshire as a rarity in which the red is replaced by yellow, and this has hitherto been seen nowhere else. It is beyond our immediate purposes to discuss the genetic relationships of such forms, but the details of this case are interesting as making fairly clear the fact that the distinctions between _castanea_ and _neglecta_ are due to combinations of the presence of and absence of two pairs of factors, of which one produces a red pigment in the ground colour of the forewing and the other irrorates the same region with black scales. Mr. Woodforde states that all intermediates exist, and that in Staffordshire the greys always have a pinkish tinge. The yellow is doubtless another recessive to the red. Species which are uniform in some localities may be polymorphic in others. Such a phenomenon is well exemplified by the orchid _Aceras hircina_. Of this species distinct varieties had previously been known in Germany, but Gallé[9] has lately given a detailed account of a number of most diverse forms found growing in a district of Eastern France. Without reference to his plates it is impossible to give any adequate conception of the profusion of types which the flowers of the species there assume. In some the lip is elongated to many times its usual length, twisting and dividing in a fashion suggesting some of the strangest of the Tropical Orchids. In others the labellum and the lateral petals are all comparatively short and wide (Fig. 13). Intermediates, combining these qualities in various degrees, were abundant, and the condition of the species, which was the only representative of the genus in the locality, recalls the extreme polymorphism of many of the Noctuid Moths. [Illustration: FIG. 13. Various forms of _Aceras hircina_. (After Gallé.) This figure only shows a few of the more striking forms illustrated in Gallé's plates.] Somewhat comparable variability has been seen in another Orchid genus _Ophrys_. In Great Britain the species _apifera_, _aranifera_ and _muscifera_ though variable are fairly distinct, but Moggridge has published two series of plates[10] showing a very different state of things as regards the _Ophrys_ population of the Riviera. Here the outward diversity is such that the ordinary specific names cannot be applied with any confidence and the limits of the species are quite uncertain. It may well be supposed that these Riviera plants are interbreeding, and indeed we may safely assume that they are. It is, however, to be remembered that Darwin showed _apifera_ in this country to be habitually self-fertilised, so that the different behaviour on the Riviera may itself constitute a local peculiarity. Moreover it is to be gathered from Moggridge's account that in the districts which he examined the condition was not to be described by the statement that our three types were there co-existing and hybridising, but rather we should say that the population was polymorphic, containing these three types amongst others. Conchologists are aware that on the Dogger Bank _Modiola_ attains a size unparalleled elsewhere. The same is true of the sponges _Grantia compressa_ and _Grantia ciliata_ in the estuary of the Orwell.[11] Conversely, as we know so well in the case of Man, dwarf races occur in several special localities. Such examples may be multiplied indefinitely. The relation of local forms to species has often been discussed from many points of view, but I know no treatment of the subject clearer or more comprehensive than an excellent account of some of the various manifestations of local differentiation as they appear in Helicidæ published by Coutagne[12] and a reader interested in the problem which they raise would do well to make himself acquainted with the original from which the following notes are taken. He speaks for example of _Helix lapicida_. This is on the whole a constant form ranging up to the altitude of 1,300 m., common all over France except at great heights and in the Olive regions where it is restricted to moist places. Though subjected to such diverse conditions it shows only trivial variations in colour and other respects throughout its distribution, excepting that on both sides of the Pyrenees it has a very distinct sporadic variety called _Andorrica_ or _microporus_. This variety occurs here and there, together with the type-form sometimes in colonies (pp. 26-30 and 86). _Bulimus detritus_ though more restricted in geographical range is a much more variable form. It exhibits great variations in colour, form, and size, and as Coutagne well insists, these are independent of each other. Foreshadowing the methods of factorial analysis he suggests that distinctions in each respect, the "modes" as he calls them, should be denoted by a letter, or if desired, by a name, and the several combinations of differences might thus be most logically and usefully expressed. Of such combinations he says there are at least 18, all of which can be found. The whole possible series does not necessarily occur in the same place, and various localities are characterised by the presence or absence of certain of the combinations as Coutagne calls them, and by the relative frequency with which they occur. The ideas thus enunciated are much in advance of the ordinary practice of systematists, who give names to forms which are nothing but accidental combinations of factors, just as the horticulturists for practical reasons give names to similar combinations, which as we now know are merely specially noticeable terms in a long series of possibilities. In each case it is rather the _factors_ which should be named than the forms which are constituted by their casual collocation. In this special example of _Bulimus detritus_ the 18 forms are made by the combinations of three pairs of independent factors. Besides these combinations which may occur anywhere or almost anywhere in the distribution there are two more distinct local forms, each of which is regarded by Coutagne as probably constituting a fresh "mode," perhaps compatible with the others. _Helix striata_ (Draparnauld)[13] is truly polymorphic; and its various forms have been described under various specific names. It abounds in the calcareous hills of Provence and Languedoc, disappearing in the alluvial lowlands and equally in the upper levels at about 800-1,000 m. From this district it extends through regions of similar altitude over a great part of France (details given). Locard in his monograph of this group, which he calls collectively the group of _Helix Heripensis_, tabulates 27 distinct named forms. The characteristics in which these forms differ have been reckoned as 17, and as several of these vary in degree of development, the number of modes may be increased to 109. For practical purposes however Coutagne considers that the various developments of 7 characteristics in their several combinations are enough to express the various forms, and he gives examples of this method of definition. As he observes, though names may be required to define the modes, no one need be alarmed at that, for the same names of modes will be applicable to a great range of distinct species, and the formulae expressing their combinations will replace the varietal names. This particular example of polymorphism is but little limited by locality. Occasional colonies present some special physiognomy which may in a given place seem almost invariable, though in this very respect the colonies found elsewhere may be highly variable, but such limitations are exceptional for _H. striata_. Some distinct and obvious susceptibilities to the influence of soil and climate are however noticeable. For example on siliceous ground the shells are thinner, while on calcareous soils they are thicker; similarly those from the Northern districts attain a larger size than those from further South. Moreover those subjected to curtailed development, whether from drought, heat or cold often show a shortening of the spire. In contrast with this case Coutagne describes the varieties of _Helix caespitum_, which he says are for the most part localised, quoting many illustrative cases. Another remarkable case in which locality plays a curious part is provided by the two species _Helix trochoides_ and _pyramidata_. In France generally they are distinct enough from each other, _trochoides_ being smaller and having a characteristic keel. Coutagne says that after having collected these species from more than a score of localities he came upon a colony of _trochoides_ on the island of Pomègues in which the shells were relatively enormous, most of them having only a slight keel, and a few none at all. On the other hand he received a consignment of _pyramidata_ from four localities in Sicily, all small, and one of them exactly like the _trochoides_ from Pomègues. Judging by the samples received from Sicily, _trochoides_ is there not more variable than it is in Provence, while the Sicilian _pyramidata_ is protean. The relations of the two species _Helix nemoralis_ and _hortensis_ provide an illustration of another kind of manifestation of local peculiarity. _H. hortensis_ and _nemoralis_ as usually met with, are two very distinct forms. _H. hortensis_ is smaller and duller, and its peristome is white. _H. nemoralis_ is larger and more shiny, and its peristome is brown. In several anatomical points, moreover, especially in the shape of the dart, there are great differences. For a full account of these peculiarities of the two forms and a discussion of their inter-relations the reader is referred to the elaborate work of A. Lang[14] who has studied them extensively and has also succeeded in experimentally raising hybrids between them. These hybrids were in a slight degree fertile with both the parent species, but up to the time of publication no young had been reared from hybrids _inter se_. Coutagne describes the result of collections made in 62 French localities. Some had exclusively _hortensis_, some exclusively _nemoralis_, and in some the two were found in association. He gives details of five of these collections from which I take the following summary of the more essential facts, omitting much that is almost equally significant. _Locality A_, near Honfleur. Both forms present, each sharply and normally distinguished, without any intermediates. They are thus found in many places. Coutagne instances Müller's observations in Denmark, his own series from the Jura, etc. _Locality B._ Vonges (Côte d'Or), 242 _hortensis_ taken at random, showed 128 with light peristomes (either more or less pinkish or quite white) and 114 with dark _brown_ peristomes; together with 26 _nemoralis_ all with the usual brown peristomes. Of the _hortensis_ 50 were in ground-colour _opalescens_ and 1 _roseus_; and in shape 5 were _umbilicatus_. _Locality C_, about 3 kilometres from _B_. There were found 35 _hortensis_, of which 20 had light peristomes and 15 brown; together with 7 _nemoralis_. Of the _hortensis_ none were _opalescens_; 18 were _roseus_ and none has the shape of _umbilicatus_. _Locality D_, about 1,200 metres from _B_. 147 _hortensis_, of which 4 had light peristomes and 143 had brown. No _nemoralis_ were found. None of the _hortensis_ were _opalescens_ or _roseus_, but 30 were _umbilicatus_. In these localities intermediates of every grade existed between the well-characterised _opalescens_, _roseus_, or _umbilicatus_, and the other forms, but there were no intergrades between the other _nemoralis_ and the smaller _hortensis_, about which there was no hesitation. In the next locality a very different state of things was found. _Locality E._ Banks of the Yvette at Orsay (Seine-et-Oise). The actual numbers are not given, but we are told that 58 per cent. were _hortensis_, 33 per cent. _nemoralis_, and 9 per cent. intermediate. As at Honfleur, the _hortensis_ had white peristomes, and the _nemoralis_ brown. Coutagne's visits to this locality were in 1878 and 1880, and he calls attention to the fact that Pascal found similar intermediates in the same neighbourhood in 1873. The two species, in Coutagne's view, when they occur together, can generally be sorted from each other with perfect confidence, and it is only in exceptional localities that these intermediates occur. Whether they are hybrids, or whether sometimes the species in their variations transgress their usual limitations is regarded both by Coutagne and by Lang as a question not yet answerable with certainty. Coutagne moreover lays stress on the fact that although each species may be easily known from the other _in its own district_, yet when shells from different districts are brought together it is sometimes impossible to sort them. He mentions an example of such casual intermixture occurring under natural conditions on an island in the Rhone, to which it may well be supposed that floods had brought immigrants from miscellaneous localities. This population contained a very large number of uncertain specimens, and as he says, it was much as if he were to mix the shells from his 62 localities, after which it would certainly be impossible to separate the two species again.[15] Further evidence is given in the same treatise as to other examples of polymorphism, especially in the genus _Anodonta_, of which Locard made 251 species for France alone. Here again are cases like those already given, and many forms or "modes" are found restricted to special localities, while occasionally in the same locality dissimilar forms are found, collectively forming a colony, without intermediates. Taken as a whole the evidence shows the following conclusions to be true. Local races, whether of animals or plants, may be distinguished by characters which we are compelled to regard as trivial, or again by features of such magnitude that if they were known to us only as the characteristics of a uniform species they would certainly be assumed without hesitation to be essential for its maintenance. Local forms may be sharply differentiated from the corresponding populations of other localities or they may be connected with them by numbers of intermediates. Not rarely also we find a fact which has always seemed to me of special significance, that the peculiarity of the local population or colony may show itself in a special liability to variation, and this variability may show itself in one of many degrees, either in the constant possession of a definite aberration, in a dimorphism, or in an extreme polymorphism. At this stage attention should be called to two points. First, that when the details of the geographical distribution of any variable species are studied in that thorough and minute fashion which is necessary for any true knowledge of the interrelations of the several forms, the conception of a species invented by the popular expositions of Evolution under Selection is found to be rarely if ever realised in nature. A species in this generalised sense is an aggregate of individuals, none exactly alike, but varying round a normal type, the characters of which are fixed in so far as they are adapted to environmental exigency. In nature, however, the occurrence of the varieties, and even the occurrence of the variability is sporadic. In one place a population may be perfectly uniform. In another it may be again uniform but distinct. In others the two forms may occur together, sometimes with and sometimes without intergrades. In some localities a sporadic variety may be an element of the population, persisting through long periods of time. In other localities there may be several such aberrations occurring together which are absent elsewhere. Secondly, I would remind the reader that in the light of genetic analysis we know that intergrades, when they do occur, cannot be assumed to represent conditions through which the species must pass or has passed on its way to the extreme and definite forms. Often, perhaps generally, they are nothing but heterozygous forms, and often also they are conditions corresponding with the presence of factors in their reduction-stages. A broad survey of the facts shows beyond question that it is impossible to reconcile the mode of distribution of local forms with any belief that they are on the whole adaptational. Their peculiarities are occasionally the result of direct environmental influence, as we shall hereafter notice in certain cases, but none can attribute such sporadic and irregular phenomena to causes uniformly acting. Writers on systematics, especially those of former generations often conjecture or assert that local distinctions are caused by "differences of climate, soil, food, etc.," in vague general terms. It is usually safe to assume that these remarks do not represent conclusions drawn from actual evidence, for only rarely can they be translated into more precise language. So thoroughly have the biological sciences become permeated with the belief that all distinctions are dependent upon adaptation, that the mere existence of definite distinctions is felt by many to be sufficient ground to warrant an assumption that these distinctions are directly or indirectly due to special local conditions. For example, Dr. J. A. Allen, who has done so much careful and valuable work in delimiting the local forms of the United States fauna, writes of the Ground Squirrels (Tamias)[16] as follows:-- "From the extreme susceptibility of this plastic group to the influences of environment, it is one of the most instructive and fascinating groups among North American mammals. No one can doubt its comparatively recent differentiation from a common stock, and its dispersion from some common centre. Whether the type originated at some point in North America, or in the Northern part of Eurasia, it is perhaps idle to speculate, but that it has increased, multiplied, spread, and become differentiated to a wonderful degree in North America is beyond question; as it is found from the Arctic regions to the high mountain ranges of Central Mexico, and has developed some twenty to thirty very palpable local phases." "Some of them easily take rank as species, others as subspecies. Probably a more striking illustration of evolution by environment cannot be cited." He proceeds to point out that the habits of these creatures are such as lead to isolation. This may well be admitted, and indeed no exception can possibly be taken to the passage as a whole, save in the one respect that there is no real proof that the local diversity is due to "evolution by environment" or an indication of "susceptibility to the influences of environment." Dr. Allen does indeed adduce the fact that California "extending through 800 miles of latitude, with numerous sharply contrasted physiographic regions, has apparently no less than six strongly differentiated forms, while the region east of the Rocky Mountains from a little below the northern boundary of the United States northward to the limit of trees--a slightly diversified region of at least ten times the area of California--has only one"! But when one comes to ask how the various forms are adaptational, and how the influences of environment have led to their production, only conjectures of a preliminary and tentative character could be expected in reply. Desert forms are no doubt pallid as in so many instances, and forest forms are more fully coloured, and we may readily enough accept such facts as indications of a connection between bodily features and the conditions of life, but further than that no one can go; so that when we find size, length of ears or of tail, the number of dorsal stripes, the pattern of the colours, not to speak of differences in the pigments themselves, all exhibiting large modifications, we cannot refer these peculiarities to the causation of environmental difference, save as a simple expression of faith. I incline far more to agree with Gulick who, after years of study of the local variations of the Achatinellidae, came to the conclusion that it was useless to expect that such local differentiation can be referred to adaptation in any sense.[17] Even the most convinced Selectionist must hesitate before such facts as those related by A. G. Mayer regarding the distribution of _Partula otaheitana_, one of these Achatinellidae. The island of Tahiti has been scored by erosion so that a series of separated valleys radiate to the coast. From four successive valleys Mayer collected the species, and found that in the first (Tipaerui) valley all the shells were dextral (115, containing 73 young); in the second valley (Fautaua) 54 per cent. of adults and 55.5 per cent. of the young contained were sinistral; in the third valley (Hamuta) 69 per cent. of adults and 73 per cent. of young contained in them were sinistral; and lastly, in the fourth valley (Pirae) all the shells (131, containing 62 young) were sinistral.[18] In connection with these observations I may mention the fact that in a certain pond in the North of England[19] the sinistral form of _Limnaea peregra_ has been known to occur for about fifty years. Visiting it lately I found the left-handed shells to be about 3 per cent. of the population. The species is the commonest British freshwater shell, but left-handed specimens are exceedingly rare. Will anyone ask us to suppose that the persistence of a percentage of this rarity in the same place is an indication of some specially favouring circumstance in the waters of that pond? It is a horse-pond to all appearances exactly like any other horse-pond; and I believe that in perfect confidence we may accept the suggestion of common sense, which teaches us that there is nothing particular in the circumstances which either calls such varieties into existence or contributes in any direct way to their survival. Had the phenomenon of local variation been studied in detail before Darwin wrote, the attempt to make selection responsible for fixity wherever found, could never have been made. The proposition that not only the definiteness of local forms but their variability also is sporadic, can be established by countless illustrations taken from any group of either the animal or the vegetable kingdoms. Only exceptionally can the fixed differences be even suspected of contributing to adaptation, and sporadic variability, which is a no less positive fact, must manifestly lie outside the range of such suspicions. It is open to any one to suggest speculatively that the persistence of special varieties or of special variability in special places is an indication that in those places the conditions of life are such that the forms in question are tolerated though elsewhere the same types are exterminated; but that consideration, even if it could be proved to be well founded, is not one which lends much force to the thesis that definiteness of type is a consequence of Natural Selection. On the contrary, recourse to such reasoning implies the inevitable but very damaging admission that the stringency of Selection is frequently so far relaxed that two or more equally definite forms of the same species can persist side by side. There is no doubt that this is the simple truth, but when once that truth is perceived it is useless to invoke the control of Selection as the factor to which definiteness of type in general must be referred. The genetic relations of local forms to each other cannot in the absence of actual breeding experiments be often ascertained. Standfuss formerly enunciated as a general principle that when two forms co-exist in the same locality and are able to interbreed, they do not produce intermediates; but that when the forms are geographically separated as local races, crosses between them result in a series of intermediates.[20] In this aphorism there is a good deal of truth, but if in the light of Mendelian principles we examine the two statements we see now that the first is in reality only another way of saying that the distinctness of an aberrational form co-existing with another is due to segregation, accompanied by some degree of dominance of one type. Whether, however, one geographically isolated race will give intermediates when bred with another must depend entirely on the genetic physiology of the special case, and no general rule can be laid down. It may well be that, inasmuch as the distinctness of the variety is maintained by isolation, the difference in factorial composition between it and the representative form in another area is neither simple nor sharp; but when two varieties co-exist, though interbreeding, it is now clear that their differences must depend on the segregation of simple factors. Plainly such aberrations may in one place co-exist with another type, and elsewhere be separated from it as local races. Excellent illustrations of these two stages in evolution are provided by the melanic varieties of British Lepidoptera. The fact that black or blackish varieties of many species especially of Geometridae have come into existence in recent years is well known to British collectors, and it is not in dispute that they have in several instances replaced the older type more or less completely in certain districts. In the year 1900 the Evolution Committee of the Royal Society instituted a collective inquiry as to the contemporary distribution of these dark varieties. As the change had happened within living memory and had greatly progressed in recent years it was hoped that a record of the existing distribution would serve as a point of departure for future comparison. The records thus obtained were tabulated by Mr. L. Doncaster.[21] From that account and from the statements in Barrett's British Lepidoptera[22] this description of some of the more notable cases is taken. The most striking and familiar case is that of _Amphidasys betularia_, of which only the ordinary type was known in any locality until about 1848-1850, when the totally black var. _doubledayaria_ first appeared in the neighbourhood of Manchester. This black form was subsequently recorded in Huddersfield between 1860 and 1870; Kendal about 1870; Cannock Chase, 1878; Berkshire, 1885; Norfolk, Essex and Cambridge about 1892; Suffolk, 1894; London, 1897. For the Southern Counties of England, except in the London district, there are still very few records. It cannot of course be asserted positively that the variety spread from its place of first appearance into the other localities, and that it did not arise _de novo_ in them, but there can be little doubt that the process was one of colonisation. On the European Continent the first records are from Hanover in 1884, Belgium 1886 and 1894, Crefeld 188-, Berlin 1903, Dresden about the same date. As regards the increase of the variety we have the fact that in Lancashire, Cheshire and the West Riding of Yorkshire the black is now the prevalent form; and in some places, as for example, Huddersfield, the black alone is now found, though it was unknown there till between 1860 and 1870. About 1870 at Newport, Monmouth, the two forms were in about equal numbers, but a few years later the type had almost vanished. Similarly in Crefeld, where the black form was still very rare in the eighties, it now forms about 50 per cent. of the population. In the London district the black remains scarce and at the date of the report it was still very scarce. From Ireland there is only one record and there are hardly any from Scotland. _Boarmia repandata_ is another species which is behaving in a somewhat similar way. Unlike _betularia_, however, the species is a variable one, and has several colour-forms, amongst them the banded var. _conversaria_, and many others. In addition to these there is a black form in the North of England which seems to be spreading. In Huddersfield the black was first recorded in 1888, and in 1900 20-25 per cent. were black. At Rotherham the black or very dark are now prevalent and have increased in the last 15 years. From the Midlands, East Anglia and Southern Counties the returns show only the light and medium forms. Of _Odontoptera bidentata_ several intergrading dark forms exist, and these are found exclusively in the North and the Midlands. Unicolorous blacks have been found recently in the Lancashire mosses and at Wakefield. At Huddersfield 50 years ago the light forms were prevalent, but now a rather dark brown, not infrequently suffused with black, is the commonest. In Southern Counties only light forms are known. _Phigalia pilosaria_ in South England is always light, but in the North the prevalent form is darker. About 35 years ago a form with unicolorous sooty fore-wings and dull grey hind wings was first seen in Yorkshire and a similar form is now taken regularly in South Wales. In the following cases the dark varieties were found originally only in the South. _Boarmia rhomboidaria_ gave rise about 40 years ago to a unicolorous smoky variety called _perfumaria_. This was at first peculiar to the London district, but it has since been taken in Birmingham and other large cities. More lately coal-black specimens have been found at Norwich, and others similar but hardly so dark were taken in the South of Scotland and at Cannock Chase. _Eupithecia rectangulata_ is a similar case. Formerly the light forms were prevalent but within sixty years they have almost entirely been replaced in the South of London by a nearly black form. _Tephrosia_ (_Boarmia_) _consortaria_ and _Tephrosia consonaria_ are exceptionally interesting, for they have both given off dark forms in the same wood near Maidstone, which is far from the usual "centres of melanism." They were discovered in this locality by Mr. E. Goodwin. That of _consortaria_ is a dark grey, but that of _consonaria_ is a full black, and nothing like either has been found anywhere else. These examples are all taken from the Geometridae but others, though of a less conspicuous kind, could be given from the Noctuidae or the Micro-Lepidoptera. _Acronycta psi_, for instance, has a suffused form which is believed to be becoming more frequent in the London district. _Polia chi_ has two dark forms, _olivacea_, a yellowish grey with dark markings, and _suffusa_ which is a darker, blackish-slate colour. Both occur in the North of England, sometimes together, sometimes separately, or mixed with the type and many intermediates. The distribution is peculiarly irregular. At Huddersfield, where the very dark form appeared suddenly about 1890, some 30 per cent. are said to be now dark and about 6-7 per cent. very dark, but at Saddleworth, 12 miles away, only the pale forms occur. Several questions of interest arise in regard to this evidence. This progressive Melanism has arisen in certain families only, and may be confined to certain species only, within those families. As in almost all other examples in which variation has been much observed, its incidence is capricious and specific. A collateral line of inquiry relates to the degree of discontinuity which the variation manifests. Here again there is no rule. Generally speaking, in _A. betularia_, to take the case most fully studied, the variation is discontinuous. Real intermediates between _betularia_ and _doubledayaria_ are in most localities absent or rare. The black spots of _betularia_ may often be larger or more numerous than in the normal, but this variation has nothing to do with _doubledayaria_, and is not an intermediate stage towards it, though sometimes wrongly so described. _Doubledayaria_ owes its characteristic appearance to a factor which blurs the surface of the wings with a layer of black. Sometimes this blurring is slighter than in the real _doubledayaria_, and these forms are real intermediates. Occasionally the fore-wings alone are thus blurred. These intermediates are clearly due to reduction-stages of the _doubledayaria_ factor, and are related to it as a blue mouse is to a black, or a dutch rabbit to a self-colour. It cannot positively be asserted that the full _doubledayaria_ existed before the intermediate, but it almost certainly did. In certain places as for instance in Belgium, there is evidence that intermediates have at various times been fairly abundant, but they have never become common, nor are they known to exist in the absence of _doubledayaria_. When the black variety and the light type breed together they do not usually have intermediates among their offspring, and the evidence is consistent with the view that the black is a complete dominant. The same is probably true of _Tephrosia consonaria_. In some of the other species we know that the darkest forms did not appear first. For example in _Phigalia pilosaria_ and _Boarmia rhomboidaria_ dark forms existed and are believed to have increased in number before the darkest made its appearance. _Hybernia progemmaria_ is said to have become darker gradually both in Cheshire and in the West Riding, and a uniformly smoky variety appeared in South Yorkshire less than 45 years ago which has spread to neighbouring counties. The dark medium has become the commonest form in Huddersfield district, where the very dark variety is now about 20 per cent. of the population, though the light form is still common. Taking the evidence together we find it consistent with the view that dark forms have appeared sporadically, in some species the very dark appearing first and intermediates later, in others the moderately dark came first and the darkest later in time. It is practically certain that the change has in general come about not by a gradual change supervening on the population at large, but by the sporadic appearance of dark specimens as a new element in the population, and strains derived from these dark individuals have gradually superseded the normal type more or less completely. If it could be shown that these melanic novelties had a definite advantage in the struggle for existence they would provide an instance of evolution proceeding much in the way which Darwin contemplated. The whole process would differ from that conceived by him as the normal method of evolution only in so far as the change has come about with great rapidity and in some instances largely by the appearance and success of discontinuous varieties. The question, however, must be asked whether the dark form can reasonably be supposed to have an advantage by reason of their darkness. Some naturalists believe that the darkness of the colours does thus definitely contribute to their protection by making the insects less conspicuous and thus more likely to escape the search of birds. In support of this view it may be pointed out that it is in the manufacturing districts of Lancashire and Yorkshire, and again in the London area that the melanics have attained their greatest development. Consistently with this argument also, it is in the neighbourhood of Crefeld and Essen, the black country of Germany, that they have chiefly established themselves on the Continent, and _Phigalia pilosaria_ in the black form is now at home in South Wales. Thus superficially regarded, the evidence looks rather strong, but it is difficult to apply the reasoning in detail. We have first the difficulty that the black form of _betularia_ for instance has established itself in thoroughly rural districts, notably near King's Lynn in Norfolk, and in the neighbourhood of Kendal and Windermere. The black form of _consonaria_ and the dark _consortaria_ appeared in a wood near Maidstone, far from town smoke, and the black _rhomboidaria_ was first found at Norwich, which, as towns go, is clean. Then again the spread of the melanics is very irregular and unaccountable. The black _pilosaria_ is found both in the West Riding and in the Swansea district, but not yet elsewhere. It rapidly increased at Huddersfield, but made no noticeable progress at Sheffield though recorded there for ten years. It is also a remarkable fact that no similar melanic development has been observed in America, and, so far as I am aware, comparable melanic varieties have not appeared on the European continent except in the case of the few sorts which possibly may have come from England. The whole subject is beset with complications. It must not be forgotten that in a few species of moths there is an obvious and recognised conformity between the colours of the perfect insect and that of the soil on which they live, comparable with that which is so striking in the case of some Oedipodidae and other grasshoppers. Of this phenomenon the clearest example is _Gnophos obscurata_, which is a most variable species with many local forms. Of these a well-known dark variety lives on the peaty heaths of the New Forest and other districts, but on the chalk hills of Kent, Sussex and Surrey various light varieties are found, of which one is a bright silvery white, very near in colour to the colour of a chalky bank. This case does not seem to be one of direct environmental action,[23] for Poulton found no change induced by rearing larvae among either white or black surrounding objects. No one however can doubt that there is some indirect connection between the colour of the ground and that of the moths. To my mind there is a serious objection to the theory of protective resemblance in application to such a case as that of the _betularia_ forms, which arises from the fact that the black _doubledayaria_ is a fairly conspicuous insect anywhere except perhaps on actually black materials, which are not common in any locality. Tree trunks and walls are dirty in smoky districts but they are not often black, and I doubt whether in the neighbourhood of Rotherham, for instance, which is one of the great melanic centres, _doubledayaria_ can be harder for a bird to find than _betularia_ would be. After all, too, many of the species much affected are not urban insects. They live in country places between the towns, and the general tone of these places even in Lancashire and the West Riding is not very different from that of similar places elsewhere. As against the objection that the black varieties are much blacker than the case requires it may be replied that we know nothing of the senses of birds, and that perhaps to their eyes blackness does constitute a disguise even though the surroundings are much less dark. This is undeniable, but recourse to such an argument is dangerous; for if the sight of the insect-eating birds is so dull that it does not distinguish dark things from dingy grey, we cannot subsequently regard the keen sight of birds as the sufficient control which has led to the minute and detailed resemblance of many insects to their surroundings. Those who see in such cases examples of the omnipotence of Selection must frequently find themselves in this dilemma. Taking the evidence as a whole, we may say that it fairly suggests the existence of some connection between modern urban developments and the appearance and rise of the melanic varieties. More than that we cannot yet affirm. It is a subject in which problems open up on every side, and all of them are profitable subjects for investigation. Unhappily such animals are difficult to rear successfully in captivity for many generations, owing to their extreme liability to disease. Not the least interesting feature of the melanics is the fact that the black varieties provide about the best and clearest example of a new dominant factor attaching itself to a wild species in recent times. None of the cases are satisfactorily recorded or analysed as yet, but the evidence is clear that _doubledayaria_ is a dominant to its type, and in several other dark varieties, though the pigment deposited is not black, the records show that the increased amount of the pigment almost certainly is due to a positive factor. Of this, _Hemerophila abruptaria_ is a good example.[24] There are some irregularities in the results, but taken together they leave little doubt that the dark brown variety is a dominant and the light, yellowish brown a recessive. A curious parallel to the rise of the melanic moths in England is provided by the case of the Honey-creepers or Sugar-birds, in certain West Indian islands.[25] These birds of the genus _Coereba_ (_Certhiola_) range from Southern Mexico to the Northern parts of South America and through the whole chain of the West Indian islands and Bahamas except Cuba. There are numerous local forms, and many of the islands have types peculiar to themselves, as is usual in such cases. Some of the types or species range through several islands, but according to Austin Clark[26] no island has more than one of them. Cory[27] reckoned twelve such species within the Antillean region. They are small birds about the size of a nuthatch with a general colouring of black, yellow, and white. From the island of St. Vincent the Smithsonian Institution received in the late seventies of last century several completely black specimens in addition to two of the usual type of colouring. The black were described by W. N. Lawrence as _atrata_, and those marked with the usual yellow and white were called _saccharina_. The collector (Mr. F. A. Ober) reported that the black form was common, and that the _saccharina_ form was rarer. Lawrence remarks, "Had there been only a single example (of the black form) I should have considered it as probably a case of abnormal colouring, but it seems to be a representative form of the genus in this island."[28] There is of course no doubt of the correctness of the view taken by Austin Clark that "_atrata_" is a black variety. The black bird is in every respect, other than colour, identical with _saccharina_, and it is even possible to detect a greenish colour in the areas which would normally be yellow, showing plainly enough the yellow pigment obscured by the black. We have next the interesting fact that like our melanic moths the dark form is replacing the "type." At the time of Ober's visit the type was already in a minority, but now it is nearly or perhaps actually extinct, though the black form is one of the commonest birds on the island. Austin Clark found no specimen when he collected there in 1903-4, though formerly it was not uncommon in the vicinity of Kingston and in the immediate windward district of St. Vincent. The Grenadines are geographically just south of St. Vincent, though separated by a deep channel. In these islands no black forms have yet been taken, but Grenada, the next island to the south, has both normals and blacks. There are trifling differences of size between the Grenada birds and those from St. Vincent, the Grenada specimens being slightly smaller and for this reason they have received distinct names, the form marked with yellow and white being called _Godmani_ (Cory) and the black, _Wellsi_ (Cory), but this merely introduces a useless complication. There is evidence that in Grenada, as in St. Vincent, the black is gradually ousting the original type, but the process has not gone so far as in St. Vincent. Austin Clark very properly compares this case of the Sugar-birds with that of _Papilio turnus_, which as is well-known, has a black female in the southern parts of its distribution, in addition to a female of the yellow type, but in the Northern States the black female does not occur. During the present year P. R. Lowe, who lately studied _Coerebas_ on a large scale in the West Indies, has published an important paper on the subject.[29] He calls attention to the fact that Cory recently found a black form of _Coereba_ on Los Roques Islands, and he himself discovered another on the Testigos Islands. Both localities are on the coast of Venezuela, far from St. Vincent and Grenada. The whole problem is thus further complicated by the fact that the black varieties have, as we are almost driven to admit, arisen independently in remote places. Improbable as this conclusion may be, it is still more difficult to regard all the black forms as derived from one source. For first, they present definite small differences from each other; and secondly we have to remember a consideration of greater importance, that the very fact that each island has its own type must be accepted as proving that the localities are effectively isolated from each other, and that migration must be a very rare event. The rarity of such illustrative cases is, I believe, more apparent than real. It is probably due to the extreme reluctance of systematists to admit that such things can be, and of course to the almost complete absence of knowledge as to the genetic behaviour of wild animals and plants. Only in such examples as this of the _Coereba_, where colour constitutes the sole difference, or that of the moths which have been minutely studied by many collectors, does the significance of the facts appear. The arrangement of catalogues and collections is such that much practical difficulty of a quite unnecessary kind is introduced. For example, in this very case of _Coereba_, I find the British Museum has a fine series from Grenada including 3 normals and 11 black, and also 16 blacks from St. Vincent. If the black specimens from Grenada were put with the normals which are almost certainly nothing but a recessive form of the same bird, the variation would strike the eye on even a superficial glance at the drawer. But following the notions so naively expressed in the passage quoted above from W. N. Lawrence, the blacks from Grenada are put apart together with the other blacks from St. Vincent, though two of them were shot on the same date as one of the normals. FOOTNOTES: [1] For the evidence see Tutt, J. W., _Trans. Ent. Soc._, 1898, p. 17. Compare the remarkable case given by Gulick (_Evolution Racial and Habitudinal_, p. 123) of the two races of _Cicada_, which are separated by reason of their life-cycles, one having a period of 13, the other 17 years. [2] For references see _Materials_, p. 396, and also G. Baur, _Amer. Nat._, 1893, July, p. 677. [3] Jenner Weir, _Entomologist_, 1880, XIII, p. 251. [4] Jentink, _Notes Leyden Mus._, 1885, VII, p. 111. Specimens illustrating this peculiarity are in the British Museum. [5] _Proc. Zool. Soc._, 1895, p. 850. Plate. Many points beyond that mentioned above are involved in this remarkable case. For example, not only are there males like females, but a small proportion of females resemble the ordinary male type. The stripes are not merely the spots produced, for they occupy different anatomical positions. The spots almost always go with a black ventral surface, but the striped forms nearly always have that region testaceous. _Spartium retama_, the food-plant, will not grow in England, but if it could be naturalised in America the whole problem might be investigated there and results of exceptional interest would almost certainly be attained. [6] Doncaster, L., _Proc. Zool. Soc._, 1905, II, p. 528. [7] I am not aware that the details of this striking case have ever been worked out. It should be noted that the green and blue forms are not due to simple modification of the red pigment; for these colours, due to interference, fork over the area occupied by the red lines. The distinctions between these forms cannot therefore be simply chemical, as we may suppose them to be, for instance, in the case of many red and yellow forms, and the genetic relationships of the _Heliconid_ varieties would raise many novel problems and be well worth studying experimentally. [8] Woodeforde, F. C., _Trans. North Staffordshire Field Club_, XXXV, 1901, Plate. [9] E. Gallé, _Compte Rendus du Congres Internat. de Bot. a l'Expos. Univ._, 1900, p. 112. [10] Flora of Mentone, 1864-8, _Nova Acta Acad. Caes._, XXXV, 1869. [11] I owe these facts to Canon A. M. Norman, who showed me illustrative specimens. They were originally described by Bowerbank (_Monogr. Brit. Spongiadae_, vol. II, pp. 18 and XX; vol. III, Pls. I and III). A specimen of _G. compressa_ measured 5 inches, with a greatest width of 3-1/4 in. _G. ciliata_ was found measuring 3 in. long and 3/4 in. wide. These dimensions are many times those of normal specimens. [12] Coutagne, G., _Recherches sur le Polymorphisme des Mollusques de France_, _Annales Soc. d'Agric. Sci. et Industr. Lyon_, 1895. [13] As to the synonymy and references see Coutagne, p. 45. [14] A. Lang, _Die Bastarde von H. hortensis Muller H. nemoralis L._ Jena, G. Fischer, 1908; with a fine coloured plate showing the varieties of the species and their hybrids. [15] With this evidence compare that given by A. Delcourt in his valuable papers lately published relating to the variations of _Notonecta_. See especially _Bull. Sci. Fr. Belg._, 1909, XLIII, p. 443; and _C. R. Soc. Biol._, 1909, LXVI, p. 589. [16] Allen, J. A., _Bull. Amer. Mus. N. H._, III, 1891, pp. 51-54. [17] J. T. Gulick, _Evolution, Racial and Habitudinal_, Carnegie Institution, Publication No. 25, 1905. [18] A. G. Mayer, _Mem. Mus. Comp. Anat. Harvard_, Vol. XXVI, 1902, p. 117. From the tables given I cannot ascertain the actual numbers from the two intermediate valleys, but they were considerable. [19] To which I was very kindly guided by Mr. C. T. Trechmann. [20] Standfuss, _Handbuch d. paläarkt Gross-schmet_, 1896, p. 321. [21] _Ent. Rec._, XVIII, No. 7, 1906. [22] This evidence was largely collected by Mr. G. T. Porritt, who has given much attention to the subject. [23] Such direct action has of course been proved to occur in the case of several dimorphic larvae (_e. g._, _A. betularia_, itself) and pupae. [24] See Harris, _Proc. Ent. Soc. London_, 1904, p. lxxii, and 1905, p. lxiii; also Hamling, _Trans. City of London Ent. Soc._, 1905, p. 5. [25] I am indebted to Mr. Outram Bangs of the Harvard Museum for calling my attention to this remarkable case. [26] _Auk_, 1889, VI, p. 219. [27] _Ann. N. Y. Acad. Sci._, 1878, I, p. 149. [28] _Ann. N. Y. Acad. Sci._, 1878, I, p. 149. [29] _Ibid_, 1912, pp. 523-8. CHAPTER VII LOCAL DIFFERENTIATION. _Continued_ OVERLAPPING FORMS The facts of the distribution of local forms on the whole are consistent with the view that these forms come into existence by the sporadic appearance of varieties in a population, rather than by transformation of the population as a whole. Of such sporadically occurring varieties there are examples in great abundance, though by the nature of the case it can be but rarely that we are able to produce evidence of a previous type being actually superseded by the variety. When the two forms are found co-existing in the same area they are usually recorded as one species if intergrades are observed, and as two species if the intergrades are absent. On the other hand when two forms are found occupying separate areas, when, that is, the process of replacement is completed in one of the areas, then forthwith each is named separately either as species or subspecies. Successive observations carried out through considerable periods of time would be necessary to establish beyond question that the history proceeds in one way rather than another. Such continuity of observation has for the most part never been attempted. The kind of information wanted has indeed only been lately recognized, and really critical collecting is a thing of only the last few decades. The methods of the older collectors, who aimed at bringing together a few typical specimens of all distinct forms, are of little service in this class of inquiry, which is better promoted by the indiscriminate collection of large numbers of common forms from many localities. When this has been done on a comprehensive scale we shall be in a position to form much more confident judgments as to the general theory of evolution. Some little work of the kind has however been done and the results are already of great value. Seeing that the differentiation of local forms is only made possible by isolation, it necessarily happens that the collector finds one form in one locality and another in a distinct locality, and there is no evidence as to the behaviour which the two representative species might exhibit if they came into touch with each other. In the most familiar examples of such distinction each inhabits an island, completely occupying it to the exclusion of any other similar form. It can only be when the two representative species occupy parts of a continental area connected with each other by regions habitable for the organism in question, that there is a chance of seeing the two forms in contact. Often also, even where this condition is satisfied, the habits, social organisation, or some other special cause may act as a barrier which prevents the distinguishable forms from ever coming into such complete contact as to interbreed or to behave as a genetically continuous race. When genetic continuity is ensured by a constant diffusion of the population over the whole area which they inhabit there will manifestly be no formation of local races. The practical uniformity, for example, of so many species of birds which inhabit widely extended ranges of Western Europe is doubtless maintained by such constant diffusion. When, as in the case of the Falcons, many localities have peculiar forms, the fact may be taken as conclusive evidence that there is little or no diffusion; and when we find in such a species as the Goldfinch that in spite of migratory fluctuations there are nevertheless geographical races fairly well differentiated, it may similarly be inferred that these fluctuations habitually move up and down on paths which do not intermingle. There are however a few examples of animals, not given to much irregular wandering, which occupy a wide and continuous range of diversified country and are differentiated as local races in two or more districts, though the distinct races meet in intervening areas. Of these the most notorious illustration which has been investigated with any thoroughness is that of the species of _Colaptes_ (Woodpeckers) known in the United States as Flickers. The study of the variations of these forms, made by J. A. Allen[1] is an admirable piece of work, with which every student of variation and evolutionary problems should make himself familiar. The two forms with which we are most concerned are known as _C. auratus_ and _C. cafer_, and are very strikingly different in appearance. In size, proportions, general pattern of colouration, habits, and notes, the two are alike, but they differ in the following seven respects as stated by Allen. _Auratus_ _Cafer_ 1. Quills _yellow_. 1. Quills _red_. 2. Male with a _black_ malar 2. Male with a _red_ stripe. malar stripe. 3. Adult female with _no_ 3. Adult female with usually a malar stripe. brown malar stripe. 4. _A scarlet nuchal crescent 4. No nuchal crescent in in both sexes._ either sex. 5. Throat and fore neck 5. Throat and fore neck _brown_. _grey_. 6. Whole top of head and hind neck 6. Whole top of neck and hind _grey_. neck _brown_. 7. General plumage with an 7. General plumage with a _olivaceous_ cast. _rufescent_ cast. These differences are illustrated in the accompanying coloured plate, which has been most kindly prepared for me under the instructions of Dr. F. M. Chapman of the American Museum of Natural History. Before going further it is worth considering the nature of these differences a little more closely. All but the last are large differences which no one would overlook even in a hasty glance at the birds. If the only distinction lay in the colour of the quills we might feel fairly sure that _auratus_ was a recessive form of _cafer_, and so probably it is in this respect. Similarly the black malar stripe of _auratus_ is in all probability recessive to the red malar stripe of _cafer_ and I imagine the pigments concerned are comparable with those in the Gouldian Finch (_Poephila gouldiae_) of Australia. Both sexes in that species may have the head black, red, or, less often, yellow, and though it is not any longer in question that birds may breed in either plumage, I believe that the young are always black-headed and I imagine that those which become red-headed possess a dominant factor absent from the permanently black-headed birds.[2] Yellow as a recessive form of a red is certainly very common, but red and black as variants of the same pigment are less usual. In the Gouldian Finch we seem to have a case where a pigment can assume all three forms. It would be interesting to know whether the red of the malar stripes in _Colaptes_ is a pigment of the same nature as the red of the quills. Both in _Colaptes_ and in _Poephila gouldiae_ I have seen specimens intermediate between the black and the red, and the appearance of the part affected was exactly alike in the two cases, red feathers coming up among the black ones, and many feathers containing both red and black pigments mixed together. The development of the scarlet nuchal crescent in _auratus_ and the absence of this conspicuous mark in _cafer_ constitute from the physiological point of view the most remarkable pair of differences. When the red crescent is not formed, the feathers which would bear it are exactly like the rest, and no special pigment is visible in them which one can regard as ready to be modified into red. If the crescent is due to a factor it must therefore be supposed that this factor has the power of modifying the pigment of the neck in one special place alone. Dr. W. D. Miller called my attention to the fact that a similar variation occurs in another American woodpecker, the Sapsucker, _Sphyropicus varius_.[3] I do not suggest that such variations are without parallel: indeed in _P. gouldiae_ the factor which turns the black of the head into scarlet affects one special region of the black only, being sharply distinct from the unmodified black of the throat. These regions of the head are however often the seat of special colours in birds.[4] So also may be instanced the variety of the Common Guillemot (_Uria troile_) which has a white line round the eyes and at the sides of the head where the normal has no such mark; but this line is formed in a very special place, the groove joining the eye to the ear, whereas the feathers of the nuchal crescent are not ostensibly distinguished from those adjacent.[5] The transposition of the brown and the grey on the back and front of the neck also constitutes a very remarkable difference. If either grey or brown depends on a factor then it must be supposed that _auratus_ has one of these factors and _cafer_ the other. From these several considerations it is quite clear that if _auratus_ and _cafer_ are modifications of the same type produced by presence or absence of factors, several independent elements must be concerned, and to unravel their inter-relations would be most difficult even if it were possible to breed the types under observation, which is of course quite beyond present possibilities. The distribution of the two is as follows. On the east side of the Continent _C. auratus_, relatively pure, occupies the whole of Canada and the States from the North to Galveston. Westward it extends across the whole continent in the more northern region to Alaska, but in its pure form it only reaches down the Pacific coast to about the northern border of British Columbia. Its southern and western limit is thus roughly a line drawn from north of Vancouver, southeast to North Dakota and then south to Galveston. _C. cafer_ in the comparatively pure form inhabits Mexico, Arizona, California (except Lower California and the opposite coast), central and western Nevada, Utah, Oregon, and is bounded on the east by a line drawn from the Pacific south of Washington, south and eastward through Colorado to the mouth of the Rio Grande or the Gulf of Mexico. Between the two lines thus roughly defined is a band of country about 1,200-1,300 miles long and 300-400 miles wide, which contains some normal birds of each type, but chiefly birds exhibiting the characters of both, mixed together in various and irregular ways. Even in the areas occupied by the pure forms occasional birds are recorded with more or less indication of characteristics of the other form, but within the area in which the two forms are conterminous, the mixed birds are in the majority. The condition of these birds of mixed character is described by Allen as follows: "As has been long known--indeed, as shown by Baird in 1858--the 'intermediates' or 'hybrids' present ever-varying combinations of the characters of the two birds, from individuals of _C. auratus_ presenting only the slightest traces of the characters of _C. cafer_, or, conversely--individuals of _C. cafer_ presenting only the slightest traces of the characters of _C. auratus_--to birds in which the characters of the two are about equally blended. Thus we may have _C. auratus_ with merely a few red feathers in the black malar stripe, or with the quills merely slightly flushed with orange, or _C. cafer_ with either merely a few black feathers in the red malar stripe, or a few red feathers at the sides of the nape, or an incipient, barely traceable scarlet nuchal crescent. Where the blending of the characters is more strongly marked, the quills may be orange-yellow or orange-red, or of any shade between yellow and red, with the other features of the two birds about equally blended. But such examples are exceptional, an unsymmetrical blending being the rule, the two sides of the same bird being often unlike. The quills of the tail, for example, may be part red and part yellow, the number of yellow or red feathers varying in different individuals, and very often in the opposite sides of the tail in the same bird. The same irregularity occurs also, but apparently less frequently, in the quills of the wings. In such cases the quills may be mostly yellow with a few red or orange quills intermixed, or red with a similar mixture of yellow. A bird may have the general colouration of true _cafer_ combined with a well-developed nuchal crescent, or nearly pure _auratus_ with the red malar stripes of a _cafer_. Sometimes the body plumage is that of _C. auratus_ with the head nearly as in pure _cafer_, or exactly the reverse may occur. Or we may have the general plumage as in _cafer_ with the throat and crown as in _auratus_, and the malar stripe either red or black, or mixed red and black, and so on in almost endless variations, it being rare to find, even in birds of the same nest, two individuals alike in all their features of colouration. Usually the first trace of _cafer_ seen in _auratus_ manifests itself as a mixture of red in the black malar stripe, either as a few red feathers, or as a tipping of the black feathers with red, or with merely the basal portion of the feathers red. Sometimes, however, there is a mixture of orange or reddish quills, while the malar stripe remains normal. In _C. cafer_ the traces of _auratus_ are usually shown by a tendency to an incipient nuchal crescent, represented often by merely a few red-tipped feathers on the sides of the nape; at other times by a slight mixture of black in the red malar stripe." Such a state of things accords very imperfectly with expectations under any received theory of Evolution. As in some of the instances discussed in the first chapter we have here two fairly definite forms, nearly allied, which on any evolutionary hypothesis must have been evolved either the one from the other, or both from a third form at a time not very remote from the present, as time must be measured in evolution. Yet though intermediates exist in some quantity, no one can for a moment suggest that they are that definite intermediate from which _auratus_ and _cafer_ descend in common. One cannot imagine that the immediate ancestor of these birds was a mosaic, made up of asymmetrical patches of each sort: but that is what many of the intermediates are. It is not much easier to suppose the ancestor to have been a nondescript, with a compromise between the developed characters of each, with quills buff, malar stripes neither black nor red, with a trace of nuchal crescent, and so on. Such Frankenstein-monsters have played, a considerable part in the imaginations of evolutionary philosophers, but if it were true that there was once a population of these monsters capable of successful existence, surely they should now be found as a population occupying the neutral zone between the two modern forms. Yet, though much remains to be done in clearing up the facts, one thing is certain, namely that the neutral zone has not a definite and normally intermediate population, but on the contrary it is peopled by fragments of the two definite types and miscellaneous mongrels between them. On the other hand, one cannot readily suppose that either form was the parent of the other. The process must have involved both addition and loss of factors, for whatever hypothesis be adopted, such changes must be supposed to have occurred. A careful statistical tabulation of the way in which the characters are distributed in the population of the mixed zone would be of great value, and till that has been done there is little that can be said with certainty as to the genetics of these characters. In the collection of Dr. Bishop of New Haven I was very kindly allowed to examine a sample, all taken at random, near together, in Saskatchewan. There were females 4 adult, 2 young; males 4 adult and 5 young. This number, though of course insufficient, is enough to give some guide as to the degree of definiteness which the characters generally show in their variations. Of the 15 birds, 8 had simply yellow quills; 2 had red; 1 was almost red but had one yellow tail-quill; 3 were intermediate and 1 was buff. As regards the malar patch, which can only be determined properly in the adult males, 1 was red, 1 was approximately red, 2 intermediate. As to nuchal crescent 4 females had none, 2 females very slight; 7 males had it, 1 had only a slight crescent, and 1 had none. In point of quills therefore 10 were definite out of 15; in point of crescent, 11 were definite out of 15; and in point of malar patch 1 only was definite out of 4. The last is a feature directly dependent on age and so counts for less, but as regards the other two features there is some indication that the factors show definiteness in their behaviour. It must be remembered that we have no knowledge what the heterozygous form may be, and in the case of red and yellow it is probably a reddish buff. The patch-works are no doubt to be compared with other well-known pied forms, and in these we must suppose the active factor broken up, which it probably can be very easily. The asymmetry, which Allen notices as so marked a feature, in the distribution of the red and yellow quills of the tail especially, recalls that of the black markings in the pied Canaries. As is well known to students of variations _some_ pigment-factors in _some_ animals are apparently uncontrolled by symmetry, while in other specific cases symmetry is the rule. On the other hand the blackness or redness of the malar patches is, I think, as a rule nearly symmetrical. It should be mentioned that two of Dr. Bishop's young birds belonged to the same nest, one a female with _red_ quills, the other a male with _yellow_. Both are without crescent. As to the question whether certain combinations of characters occur with special frequency, the evidence is insufficient to give a definite answer. Among all the birds I have seen in America or in England I have not yet found one having the malar patches black without any nuchal crescent. Of Dr. Bishop's 8 adults not one, however, showed the combination of the three chief features normal for _auratus_ or for _cafer_. Besides the two forms that we have hitherto considered, several other local types exist, and these throw some further light on the problem. Of these the most important in this connexion is _chrysoides_, which inhabits the whole of southern California and the mainland opposite. This remarkable form is as Allen says, very different from _auratus_ except that it has the quills yellow like _auratus_, not red like _cafer_. So that we find here in the extreme west of the whole distribution a type agreeing in one of its chief features with the eastern type. Between this and _cafer_ intergrades have, according to Allen, not been found. The relations of this _chrysoides_ are, Allen thinks, rather with _mexicanoides_, a southern, smaller race with colours more intense, which inhabits Guatemala, but however that may be, it must be regarded as a _cafer_ which has lost its red quills. The island of Guadeloupe off Lower California has an island form. Beyond the other side of the continent there is also an island form of _auratus_, inhabiting Cuba, so that clearly the yellow quills can extend into the tropics. The above account is in many respects incomplete, but it suffices to give an outline of the chief facts. The whole problem is complicated by the undoubted effects of an uncertain amount of migration, and in many, perhaps all, districts, the winter population differs from the summer population of the same localities. The existence of these seasonal ebbs and flows is now well known to ornithologists, and most of the bird species of temperate regions are subject to them. Difficult as it may be to conceive the actual process of origin of the two types _auratus_ and _cafer_, it is I think still harder to suggest any possible circumstance which can have determined their development as distinct races, or which can maintain that distinctness when created. Some will no doubt be disposed to appeal once more to our ignorance and suggest that if we only knew more we should see that the yellow quills, the black "moustache" and the red crescent, specially qualify _auratus_ for the north and eastern region, and the red quills, red "moustache" and absence of crescent fit _cafer_ to the conditions of its homes. Each can judge for himself, but my own view is that this is a vain delusion, and that to cherish it merely blunts the receptivity of the mind, which if unoccupied with such fancies would be more ready to perceive the truth when at last it shall appear. Think of the range of conditions prevailing in the country occupied by _auratus_--a triangle with its apex in Florida and its base the whole Arctic region of North America. Is it seriously suggested that there is some element common to the "conditions" of such an area which demands a nuchal crescent in the Flickers, though the birds of the _cafer_ area, almost equally varied, can dispense with the same character? Curiously enough, the geographical variation of _Sphyropicus varius_, another though a very different Woodpecker[6] shows that conversely the nuchal crescent can be dispensed with in the Eastern form though it is assumed by the Western.[7] Allen points out the interesting additional fact that superposed upon each of the two distinct forms, _auratus_ and _cafer_, are many geographical variations which can very naturally be regarded as climatic. Each decreases in size from the North southward, as so many species do.[8] They become paler in the arid plains, and show the ordinary phases which are seen in other birds having the same distribution. Such differences we may well suppose to be determined directly or indirectly, by environment, and we may anticipate with fuller knowledge it will be possible to distinguish variations of this nature as in the broad sense environmental, from the larger differences separating the two main types of _Colaptes_, which I surmise are altogether independent of such influences. It is generally supposed that phenomena like those now so well established in the case of _Colaptes_ are very exceptional, and as has already been stated a number of circumstances must combine in order that they may be produced. I suspect however that the examples are more numerous than is commonly thought. In all likelihood the three forms _Sphyropicus varius_, _nuchalis_ and _ruber_ are in a very similar condition though the details have not, so far as I know, been worked out. A complex example which is closely parallel to the case of _Colaptes_ was described by F. M. Chapman[9] at the same date as Allen's work. This is the case of _Quiscalus_, the Grackles, which in the North American Continent have three fairly distinct forms which Chapman speaks of as _Q. aeneus_, _Q. quiscula_, and _Q. quiscula aglaeus_. The birds are all, so far as pigment is concerned, dark blackish brown, but the head and mantle have superposed a metallic sheen of interference-colours which in the various forms take different tints, bluish green, bronze green, or bronze purple. The details are complicated and difficult to appreciate without actual specimens, but the two common types are sufficiently distinct. The birds inhabit the whole area east of the Rockies, _quiscula aglaeus_ occupying Florida and the Southern States southwest of a band of country about a hundred miles broad extending roughly from Connecticut to the mouth of the Mississippi; and _aeneus_ taking the area north and west of this band. In discussing this case Chapman expresses the same view as Allen does in the _Colaptes_ case, that there are two distinct populations, substantially fixed, and that the band of country in which they meet each other has a mongrel population, with no consistent type, but showing miscellaneous combinations of the character of the two chief types. The warblers of the genus _Helminthophila_ provide another illustration which has points of special interest. The two chief species are _H. pinus_, which has a yellow mantle and lower parts, white bars on the wings, a black patch behind the eyes and a broad black mark on the throat; and _H. chrysoptera_ with dark grey mantle and pale whitish grey lower parts, yellow bars on the wings, and grey marks on cheeks and throat where _pinus_ has black. These two birds are exceeding distinct, and in addition their songs are quite unlike. _H. pinus_ ranges through the eastern United States up to Connecticut and Iowa. _H. chrysoptera_ is a northern form extending down to Connecticut and New Jersey. Both are migrants. In these two States, where the two types overlap, certain forms have been repeatedly found which have been described as two distinct species, _Lawrencei_ and _leucobronchialis_. Dr. L. B. Bishop and Mr. Brewster showed me two long series of _Helminthophila_ containing various intergrades between the four named kinds, and details regarding these may be found in Chapman's _North American Warblers_ and in Dr. Bishop's paper in Auk, 1905, XXII. Though the characters evidently break up to some extent, the series can be represented as due to recombinations of definite factors more easily than the others which I have described. The differentiating characters are: _Pinus_ 1. Mantle and lower parts _yellow_ (Y^1). 2. Wing-bars _white_ (y^2). 3. Cheek and throat _not black_ (b). _Chrysoptera_ 1. Mantle and lower parts _grey_ (y^1). 2. Wing-bars _yellow_ (Y^2). 3. Cheek and throat _black_ (B). The grey pigment of the mantle is common to both, but is masked by the yellow in _pinus_, the net result being an olive-green.[10] I am much indebted to Dr. F. M. Chapman for the loan of the coloured plate in which these distinctions are shown. It first appeared in his book, _North American Warblers_. We cannot tell whether _yellow_ or _not-yellow_ is due to the presence of a factor, but we may suppose that one or other gives the special colour to the parts. The black of character 3 is no doubt a dominant. Thus _pinus_ becomes Y^{1}y^{2}b and _chrysoptera_ in y^{1}Y^{2}B. The _Lawrencei_ which has the underparts _yellow_, wing-bars _white_, and _black_ patches is Y^{1}y^{2}B and _leucobronchialis_ which has mantle and underparts _not-yellow_, wing-bars _yellow_ and _no black patches_ is y^{1}Y^{2}b. This representation, it should be clearly understood, is tentative and approximate only. The characters are not really sharp, for there is much grading; but allowing for the effects of heterozygosis and for some actual breaking-up of factors I believe it gives a fairly correct view of the case. In particular we can see how it meets the difficulty which Chapman felt in accepting _leucobronchialis_ as in any sense derived from _pinus_ which has a yellow breast, and _chrysoptera_ which has a black throat, seeing that _leucobronchialis_ has neither. We now recognize at once that this form could be produced by ordinary re-combination of the absence of Y^{1} with the absence of B. I note also with great interest that the modern observers agree that the so-called hybrids may have the song either of the one species, or of the other, or a song intermediate between the two. It may also be added that these two types have several times been seen, in the breeding season, paired with each other or with one of the other combinations. [Illustration: FIG. 1. _Helminthophila pinus_, male. FIG. 2. _Helminthophila pinus_, female. FIG. 3. "Lawrence's Warbler," male; one of the integrading forms. FIG. 4. "Brewster's Warbler," male; another of the integrading forms. FIG. 5. _Helminthophila chrysoptera_, male. FIG. 6. _Helminthophila chrysoptera_, female.] Allen[11] has described another excellent American example, the Tits of the group _Baeolophus bicolor-atricristatus_. The form _bicolor_ belongs to the eastern States and ranges from the Atlantic coast to the Great Plains, and _atricristatus_, of east Mexico, extends from Vera Cruz to central Texas. In southern and central Texas the breeding ranges adjoin, and in this country various intermediates occur. The chief types differ in two main points. _B. bicolor_ Forehead varies from deep _black_ to dull black, suffused with rusty brown. Crown and crest _grey_, slightly darker than the back. _B. atricristatus_ Forehead _white_ to buffish white. Crown and crest _black_, abruptly contrasting with the back. The intergrades between the two have, as usual, received specific names. A detailed description is given by Allen, from which it appears that the gradation is very complete. In one case a series of 16 adults were all intermediates. It is not stated whether the collector took these at random, but from the local lists it is clear that the types are found not far away from the place where the intergrades were shot. Another very striking case is that of the Tanagers, of the genus _Rhamphocoelus_. In this group there are several local forms which are related to each other in remarkable ways. The forms known as _passerinii_ and _icteronotus_ exhibit the clearest phenomena of intergradation. The species _passerinii_ has a brilliant scarlet and black male, and it inhabits Honduras and Nicaragua. Proceeding southwards along the isthmus we find next _costaricensis_ which has a male like that of _passerinii_ (but a female with more orange than the olive-grey female of _passerinii_). Next we come to Panama which is occupied by _icteronotus_, sharply distinguished from _passerinii_ by the fact that the _scarlet is replaced by lemon-yellow_. This same _icteronotus_ occurs again as a pure type in Ecuador and many other parts of South America; but Colombia, _between Panama and Ecuador_, contains scarlets like _passerinii_, yellows like _icteronotus_, and various intergrades of several shades of orange. The _passerinii_ males from Nicaragua are indistinguishable from those of Colombia, and the _icteronotus_ of Ecuador are the same as those in Panama. The orange intergrades, doubtless heterozygous forms, though collected at the same locality (Medellin in Colombia) as several pure yellows and pure scarlets, are in the British Museum series sorted out as a separate species under the name _chrysonotus_! Complications are introduced by the relations of these forms to another named type, _flammigerus_, but we may for our purpose leave that out of consideration, and say that the order of geographical sequence from Honduras to Ecuador is (1) scarlet, (2) yellow, (3) mixture of types, scarlet, yellow, orange, (4)yellow. Similar examples exist in the birds of the old world, but I do not know of any that have been studied so fully as those of America. The best known is that of the two Rollers, _Coracias indicus_ which spreads from Asia Minor through Persia, Baluchistan, the Indian Peninsula and Ceylon, and _affinis_ which ranges from Nepal, through Assam, Tenasserim and the Indo-Chinese countries. The two types are very different and may be distinguished as follows: _C. indicus_ _Mantle_ drab brown-chestnut. _Breast_ chestnut. _Throat_ purplish, streaked with white. _Upper tail-coverts_ indigo. _C. affinis_ Dark olive-green. Dull purple brown. Purple, streaked with blue. Turquoise. The wings are the same in both. In the provinces of Nepal, Sikhim, and Darjiling the two species coexist, with the result that intergrades have been frequently recorded. The line of intergradation extends to the coast, and birds showing various combinations of the two types from the Calcutta district exist in collections.[12] The case is interesting inasmuch as like that of _Quiscalus_ it shows a series of combinations of various metallic colours. Some of these are probably evoked by the development of pigment behind striations or other interferences already existing, but in the present state of knowledge it would be quite impossible to suggest what the actual factors producing these appearances may be. There are, naturally, many other cases among birds which are suspected of being in reality comparable, but in most of them the evidence is still inadequate. Among Lepidoptera also there are a few of these; perhaps the most striking is that of _Basilarchia "proserpina."_[13] The genus is well known to European collectors under the name _Limenitis_, of which we in England have one species, _L. sibylla_, the "White Admiral." A species very like _sibylla_ in general appearance is common in the northern parts of the United States, ranging through Canada and Northern New England, but rarely south of Boston. This species has the conspicuous white bands across both wings like our _sibylla_. There is also a more Southern type known as _astyanax_, which is very different in its appearance, being without the white bands and having a broad irroration of blue scales on the posterior border of the hind wings. The two are so distinct that one would not be tempted to suspect any very close relation between them. In its distribution _astyanax_ is described by Field as replacing arthemis south of latitude 42°. About Boston it is much more common than _arthemis_. The two forms encroach but little on each other's territory, but where they do coexist, a third form, known as _proserpina_, is found which is almost intermediate, with the white bands much reduced. There is now no doubt that this _proserpina_ is a heterozygous form, resulting from a combination of the characters of _arthemis_ and _astyanax_. Field succeeded in rearing a brood of 16 from a _proserpina_ mother caught wild which laid 31 eggs, and of these, nine (five males, four females) resembled the mother, being _proserpina_, and seven (four males, three females) were _arthemis_. There can be no question therefore that the mother had been fertilised by a male _arthemis_ and that _no-white-band_ is a factor partially dominant over the _white band_. Another point of interest which Field observed was that the _proserpina_ female refused to lay on birch, poplar or willow, but accepted wild cherry (_Prunus serotina_) a species on which _astyanax_ can live, though that tree is not known to be eaten by _arthemis_. Incidentally also the observations show that sterility cannot be supposed to be the bar which maintains the distinctness of _arthemis_ and _astyanax_. In this connection _Papilio oregonia_ and _bairdii_ should be mentioned.[14] _P. oregonia_ is one of the numerous forms like _machaon_, but rather paler. It is a northern insect, inhabiting British Colombia east of the Cascade Range, and reaching to Colorado. _P. bairdii_ is a much darker butterfly, representing the _asterias_ group of the genus _Papilio_. Like _asterias_ it has the abdomen spotted at the sides, not banded as in the _machaon_ group. It belongs to Arizona and Utah extending into Colorado. From Colorado the form _brucei_ is described, more or less intermediate, like _bairdii_ but with the abdomen banded as in _oregonia_. W. H. Edwards records the results of rearing the offspring of the _bairdii_-like and of the _oregonia_-like mothers. Each was found able to have offspring of both kinds, that is to say, _bairdii_ females gave both forms, and _oregonia_ females gave both forms. It is not possible to say which is dominant, since the fathers were unknown. On general grounds one may expect that the _bairdii_ form will be found to dominate, but this is quite doubtful. From this particular discussion I omit reference to those examples in which the permanently established types are obviously associated with special conditions of life. Where considerable climatic differences exist between localities, or when we pass from South to North, or from the plains into Alpine levels we often find that in correspondence with the change of climate there is a change in the characteristics of a species common to both. When I say "species" in such a connection I am obviously using the term in the inclusive sense. Some would prefer to say that in the two sets of conditions two _representative species_ exist. Whichever expression be preferred it is plain that such examples present another phase of the problem we have been just considering, and in them also we have an opportunity of observing the consequences of the overlap of two closely related types, but there are advantages in considering them separately. In the examples hitherto given, with the possible exception of the Papilios,[15] the two fixed types severally range over so extensive a region that it may fairly be supposed that in the different parts they are subject to considerable diversities of climate. There is no outstanding difference that we know distinguishing the habitats of the two forms; but in comparing Alpine with Lowland forms, or essentially northern with essentially southern forms we do know an external circumstance, temperature, that may reasonably be supposed to have an influence, direct or indirect, on the population. FOOTNOTES: [1] J. A. Allen, _The North American Species of the Genus Colaptes, Considered with Special Reference to the Relationships of C. auratus and C. cafer_. Bull. Am. Mus. Nat. Hist., IV, 1892. [2] For a case in which a red-headed female � a black-headed male gave a black-headed female and a red-headed male, see _Avian Mag._, N. S., IV, pp. 49 and 329 [3] The other variations of this bird are also interesting and important. The normal male has a red head and a red throat. The female has a red head and a white throat, but varieties of the female are known with a black head, thus again illustrating the change from black to red. It should be noted that this is not a mere retention of a juvenile character, but, as the birds mature, the red feathers come up, or as an exception, the black. There is also a western species, _ruber_, in which both sexes have a great extension of red, and are alike. The male of _nuchalis_ intergrades with this type, but the female does not. [4] Dr. W. Brewster, for example, has a remarkable specimen of the Teal (_Nettion carolinense_) with a white collar strongly developed at the front and sides of the neck, in a place where the normal has no such mark. [5] This variety is spoken of as the Ringed Guillemot and is sometimes regarded as a distinct species to which the name _ringvia_ was given by Brünnich. In support of this view Dr. William Brewster, to whom I am indebted for much assistance in regard to the variation of birds, called my attention to observations of his own and also of Maynard's, that the ringed birds were sometimes mated together, though in a small minority (see Brewster, _Proc. Boston Soc. N. H._, XXII, 1883, p. 410). It would however be possible to produce many instances of varieties mated together though surrounded by a typical population (_e. g._, two varying Blackbirds, _Zoologist_, p. 2765; two varying Nightjars, _ibid._, p. 5278). I am inclined to believe that in nature matings between brothers and sisters are frequent in many species of animals, and that the production of sporadically varying colonies is thus greatly assisted. [6] The Sap-suckers feed on trees and somewhat resemble our Spotted Woodpeckers in general appearance. _Colaptes_ feeds on the ground and corresponds perhaps rather with the European Green Woodpecker. [7] For an introduction to this example I am indebted to Mr. W. D. Miller of the American Museum of Natural History. Some account of the facts is given by Baird, Brewer, and Ridgway (_A Hist. of N. Amer. Birds_. 1874, II, pp. 540, 544, etc.). _S. varius_ occupies the whole country in suitable places from the Atlantic to the eastern slopes of the Rockies, and all Mexico to Guatemala. _S. nuchalis_ was first known from the Southern Rockies only, but many were afterwards taken in Utah. _S. ruber_ is restricted to the Pacific coast. In Ridgway's opinion all three are geographical forms of one species. In _ruber_ the sexes are alike having both a great extension of the red in the throat, and a red crescent. The male of _nuchalis_ grades to the _ruber_ form, but the female does not. This female has some red in the throat like the male of _varius_, whereas the female of _varius_ has a whitish throat. [8] Not only vertebrates but the marine Crustacea and Mollusca illustrate this curious "principle" of variation, as Canon Norman formerly pointed out to me with abundant illustrations. There are of course cases to the contrary also. [9] Chapman, F. M., _Bull. Amer. Mus._, IV, 1892, p. 1; see also Ridgway, _Birds of North and Middle America_, 1902, Part II, p. 214. [10] It would aid greatly in factorial analysis if the descriptive term "green" could be avoided in application to cases where the green effect is due only to a mixture of black and yellow pigments. The absence of yellow is the sole difference between the mantle and underparts of _pinus_ and _chrysoptera_. [11] _Bull. Amer. Mus. Nat. Hist._, XXIII, 1907, p. 467. [12] References on this subject will be found in _Brit. Mus. Cat. Birds_, XVII, p. 13. [13] For these facts I am indebted to Mr. W. L. W. Field, who has lately published an account of his observations and experiments. See especially, _Psyche_, 1910, XVII, No. 3, where full references to previous publications are given. [14] For the facts and further references see W. H. Edwards, _Butterflies of N. America_, 2d series, Papilio VII and X; 3d series, 1897, Papilio IV, _Can. Entom._, 1895, XXVII, p. 239. [15] I think this case is fairly included because the _machaon_ type is so widespread that it cannot be regarded as a product of a Northern climate, nor can _asterias_ be claimed as especially a warm country form, seeing that _brevicauda_, which is scarcely distinguishable from _asterias_, inhabits Newfoundland (having a curious phase there in which the yellow is largely replaced by red). CHAPTER VIII LOCALLY DIFFERENTIATED FORMS. _Continued._ CLIMATIC VARIETIES In this chapter we will examine certain cases which illustrate phenomena comparable with those just considered, though as I have already indicated, they form to some extent a special group. The outstanding fact that emerges prominently from the study of the local forms is that when two definite types, nearly allied, and capable of interbreeding with production of fertile offspring, meet together in the region where their distributions overlap, though intergrades are habitually found, there is no normally or uniformly intermediate population occupying the area of intergradation. Such phenomena as these must, I think, be admitted to have great weight in any attempt to construct a theory of evolution. True we must hesitate in asserting their positive significance, but I see no escape from the conclusion that they throw grave doubt on conventional views. Again and again the same question presents itself. If _A_ and _B_ lately emerged from a common form why is that common form so utterly lost that it does not even maintain itself in the region of overlapping? Almost equally difficult is it, in the cases which I have numerated, to apply concrete suggestions based on any factorial scheme. We may see that in _Heliconius erato_ the type with the red mark on the hind wing probably contains a dominant factor, and that where the red mark is absent the metallic colours are exposed; and that similarly the green metallic colour may have another factor which distinguishes it from the blue. In this way we can fairly easily represent the various types of _erato_ on a factorial system as the result of the various possible combinations of two pairs of factors. But there we stop, and we are quite unable to suggest any reason why one area should have the red and the green type while another should have the blue also. So again with _Colaptes_ or the Warblers. By application of a factorial system, admittedly in a somewhat lax fashion, the genetic interrelations of the types can be represented; but how it comes about that each type maintains a high degree of integrity in its own region we can only imagine. Each has in actual fact a stability which the intermediate forms have not, but we cannot yet analyse the nature of that stability. Mendelian conceptions show us how by segregation the integrity of the factors can be in some degree maintained, but not why certain combinations of factors should be exceptionally stable. All that is left us to fall back on is the old unsatisfying suggestions that some combinations _may_ have greater viability than others, that there _may_ be a tendency for like to mate with like, and so forth. These difficulties acquire more than ordinary force in those cases in which the two fixed types inhabit regions differing in some respect so obvious and definite that we are compelled to regard each type as climatic and as specially adapted to the conditions. When for example an animal has a distinct type never met with except in Arctic or Alpine conditions, and another type proper to the plains and temperate regions, what are the characteristics of the population of intermediate latitudes or at intermediate levels? Some of the examples discussed in the last chapter may be instances of this very nature, but even if they are not, others are forthcoming which certainly are. The evidence of these cases leads to the suspicion that with further knowledge they will be found to consist of two classes, some in which the observer as he passes from the one climate to the other will find the intermediate area actually occupied by a population of intermediate character, and others in which, though we may presume the maintenance of intermediate conditions in the transitional area, there is no definite transitional population. This interrupted or discontinuous distribution seems, so far as I have means of judging, to be by far the more common of the two. I do not doubt that by sufficient search individuals representing every or almost every transitional form can be found, but it is apparently rare that _populations_ corresponding to these several grades can be seen. The question has in few if any cases been studied with precision sufficient to provide a positive answer; but I suspect that real and complete continuity, in the sense thus defined, will only be found where the character of the local populations depends _directly_ on the conditions of life, and shows an immediate response to changes in them apart from that postponed response which we suppose to be achieved by selection. Obviously the character must be one, like size for instance, capable of sensibly complete gradation. The only example I have met with of the phenomenon of anything like a complete intergradation between local types really distinct in kind is that provided by the butterfly _Pararge egeria_. It is well known to entomologists that this insect exists in two very different types, a northern one, the "Speckled Wood" of England, in which the spots are a pale whitish yellow, and a southern type having the full fulvous colour that we know as characteristic of _megaera_, the "Gatekeeper." It appears that Linnaeus gave the name _egeria_ to the southern type,[1] and our own is now called _egerides_. Broadly speaking, so far as Great Britain, France, and the Spanish Peninsula are concerned, the tawny-coloured _egeria_ occupies Spain and western France up to the latitude of Poitiers and the pale yellow _egerides_ extends from Scotland, where it has a scanty distribution, through southern England, where in suitable localities it is common, and the north of France to Paris.[2] The two types when placed side by side are strikingly different from each other, and are an excellent illustration of what is meant by climatic variation. The insect is not a great traveller and probably scarcely ever wanders far from its home. It should therefore be possible by collecting from north to south to find out how the transition is effected, whether suddenly or gradually. This at various times I have endeavoured to do, but I am still without exact information as to the population in certain critical areas. In addition to the information derived from specimens which I have collected or seen in the collections of others there is a good account of the general distribution in Europe given by the Speyers,[3] who evidently paid more attention to the subject than most lepidopterists have done, and many more recent records. In particular Oberthür[4] has published many details as to the distribution in western France and I am especially indebted to Mr. H. Rowland-Brown for a long series of notes as to the distribution in France generally, and to Mr. H. E. Page and Dr. T. A. Chapman, Mr. Oberthür Prof. Arrigoni degli Oddi, Mr. H. Williams and other correspondents, for showing me forms from many localities. The butterfly is attached for the most part to woods of deciduous trees and to country abounding in tall hedges or rough scrub. It is not usually to be found in highly cultivated districts or in very dry regions. Hence there is necessarily some want of continuity in the distribution at the present time and I should think a mile or two of arable land without big hedges would constitute a barrier hardly ever passed. The larva feeds on several coarse grasses, especially _Dactylis glomerata_. Barrett mentions also _Triticum repens_. In this country the winter is usually passed in the larval stage, but I have found that in captivity, at least, there is much irregularity. The larvæ feed whenever the weather is not very cold and may pupate, but if sharp cold comes on when they are pupating or nearly full-grown they often get killed unless protected. Some writers speak of a difference between the early and later broods, but I have never noticed this, and I do not think that the general tone of the yellow is affected by the seasons (see Tutt, _Ent. Rec._, IX, 1897, p. 37).[5] Beginning at the south of Spain the thoroughly fulvous type _egeria_ is common at Gibraltar in the Cork woods, at Granada, and doubtless generally. Lederer is said to have found only this type in Spain (Speyer), and though I have no precise information as to other places in the Peninsula north of Jaen I feel tolerably sure that there is no change from south to north.[6] Immediately north of the Pyrenees we still meet _egeria_ exclusively, and up to Poitiers at least there is no noticeable change. But somewhere between Poitiers and the bottom of the Loire valley at Tours, the genuine southern type comes to an end, and the whole population begins at the Loire to be of an intermediate type, easy to distinguish both from _egeria_ and from _egerides_. As to the exact condition of the species in the fifty miles separating St. Savin on the Vienne from places on the Loire I have no adequate information. I have only one small sample from there, but it does contain insects both of the southern and intermediate types taken on the same day, in a wood near Preuilly. Oberthür also states that at Nantes the true southern form exists in company with the northern. From this I infer that the southern form extends up the coast further than it does inland, but I imagine the representative spoken of as northern would be of usual Brittany or intermediate type. The Vienne river joins the Loire, so the true southern type reaches over into the basin of the Loire. From the Loire (Tours, Corméry) north to Calvados (Balleroy) only the intermediate is found, so far as I know, and the same type extends over Brittany.[7] In general, however, the woods near Paris have the thoroughly northern type _egerides_, but at St. Germain-en-Laye and at Etampes (Oberthür) the population approaches the intermediate type. On the whole the intermediate type is certainly less homogeneous than either of the extremes, and females with the two central spots either paler or more fulvous than the rest are not uncommon, but I have never taken one on the Loire or in Brittany which I should class with either of the extreme types. Before speaking of the distribution in other parts of France and in Europe generally I will briefly state the results of my breeding experiments. The work was done many years ago before we had the Mendelian clue, and it is greatly to be hoped that some one will find opportunities of repeating it. Crossing the English and the thoroughly southern type the families produced agree entirely with the intermediates of Brittany and the Loire. Reciprocals are alike. Of F_{2} I only succeeded in raising very few and of those that I had (about 30) nearly all were intermediate in character, though perhaps rather less uniform than F_{1}. One family alone, containing only 4 specimens, had one _egerides_, and three fulvous intermediates. As the case stands alone I hesitate whether or not to suppose it due to some mistake. Moreover from F_{1} crossed back with the respective parental types I had fairly long series, especially from F_{1} � the southern type, and looking at these families I cannot see any clear evidence of segregation. On the contrary, I think that though there are slight irregularities, they would, taken as a whole, be classed as coming between the intermediate type and the extreme form used as the second parent. This at least is true when the second parent was of the southern type. On this evidence I have regarded the case as one in which there is no good evidence of segregation and as conforming most nearly with the conventional view of gradual transition in response to climatic influences. Such influence must however be indirect; for I reared five generations of the northern type in England, and these, though they included several abnormal-looking specimens in the last generation and then died out, did not show any noticeable change from the fulvous colour of the wild type. Merrifield[8] also found that heat applied to pupae of the northern type produced no approach to the southern type. Looking at the facts now in the light of more experience it seems to me just possible that the case may be one in which, as in Nilson-Ehle's Wheats, the dominant differs from the recessive in having two pairs of factors with similar effects. The fulvous type for example may have two or more elements in separate pairs which together produce the full effect, and the intermediate may have one of these. If this were so, some segregation should of course eventually be observable, but the proportion of the various fulvous and fulvous-intermediate individuals would be large, and the reappearance of actual representatives of the northern type might be rare. I admit that this is a somewhat strained interpretation of the facts, and as yet it is not entitled to serious consideration. Nevertheless I am led to form some such expectation partly from the great difficulty in the way of any other, partly from the evidence of the small mixed sample found at Preuilly and partly from the statements given by Oberthür. There are moreover other features in the general distribution of the species which make it improbable that the dependence on climate can after all be so close. Published lists are unfortunately of little use in deciding which form occurs at a particular place, because, since the name _Meone_ has ceased to be used for the southern form, there is no complete unanimity among authors as to the application of the names _egeria_ and _egerides_, and unless more particulars are given, either name may be used for either form. Besides this, difficulty arises from the fact that the intermediate type is not generally distinguished at all, and English collectors finding it, may easily record it as the southern type. From Staudinger's note on the distribution, I gather that he, on the contrary, reckoned the intermediate with the northern type, as do the Speyers also. The late Mr. J. W. Tutt was careful to distinguish the three forms and has left several useful records. Easy therefore as it might seem to be to make out the distribution of such a familiar insect in its various modifications, there are serious practical difficulties, and until long series are brought together with this special object in view many obscurities will remain. With only the series from England, the west of France, and Spain before one it would be easy to regard the successive series of tones as a fair measure of climate; the brighter the colour, the hotter might one expect the locality to be. Such rough correspondence is often to be observed in butterflies and birds. It becomes impossible to take these simple views in the light of more complete knowledge. Beginning with France the fulvous _egeria_ occupies the lower valley of the Rhone, probably from well above Lyon, though I have no exact information respecting the country above Avignon. According to Speyer it also takes the department of Lozère. The same authority says that Puy-de-Dôme has "_egeria_," meaning perhaps the intermediate form, with the fulvous form much less commonly. Next comes the curious fact that though the Lower Rhone (Avignon, Tarascon, Nîmes) has the true fulvous form, Hyères, Cannes, Grasse, Nice, Digne, and Alassio have _the intermediate_. Savoy has the intermediate (Chambéry) and even _egerides_ perhaps, though in the same latitude on the west of France there is nothing but the fulvous type. At Chalseul and Besançon (Doubs) the ordinary northern type is found. Switzerland generally, I believe, has the northern type, but Staudinger gives _egeria_ for Valais and the intermediate occurs in Vaud.[9] The south side of the Alps has probably colonies of the pale _egerides_, and of intermediates. Orta, with a very hot summer, has the English type (Tutt, _Ent. Rec._, XII, 1900, p. 328). Locarno has the intermediate (_ibid._, XV, 1903, p. 321). North Italy in general and western Piedmont have the intermediate; but further south _egeria_ begins, at what region I do not know. Speyer gives on his own authority the remarkable statement that at Florence both extremes occur, but chiefly intermediates between the two. Mr. R. Verity however kindly informs me that in his experience this is not so, and that neither the real southern type nor the northern occur there. Sardinia, Sicily, Crete all have the southern type. Greece probably has various types. Staudinger (_Hor. Ross._, VII, 1870, p. 78) says intermediates resembling Nice types common everywhere, but from "Greece" the British Museum has a series that would pass for English specimens; and the same type occurs near Constantinople. The island of Corfu has a pale intermediate, distinct from _egerides_ but approaching it. In Roumania all three forms are recorded from various places: _egeria_ in the Dobrutscha; not quite typical (presumably an intermediate) at Bukharest; intermediate in various mountainous localities as well as in Macedonia and Dalmatia; but _egerides_ in Azuga at about 3,000 feet.[10] Hungary has the true _egerides_ also. (Cf. Caradja, _Deut. Ent. Zt._, IX, p. 58.) Mathew records the same from Gallipoli (_E. M. M._, 1881, p. 95). Staudinger does not distinguish the intermediates from the northern, but he gives "_egerides_" for Armenia and Fergana (Central Asia). As against the mere proximity of a great mountain chain being the influence which keeps the Riviera population intermediate may be mentioned the fact that the northern foothills of the Pyrenees have the pure southern type, and the climate of Cambo must surely be far cooler than that of Nice. The exact locality of the Greek specimens is not given, but there can be no part of Greece which is not much hotter in summer than Brittany, or Calvados, which have the intermediate, not the English type. In face of these facts it can scarcely be maintained that average temperature is the efficient cause of the particular tone of colour which the butterfly shows in a given region. Nevertheless it is clear that climate counts for much in determining the distribution. It is noticeable that though the pale _egerides_ can be established in a warm climate we never find _egeria_ in cold climates, and even the intermediate is not found in places that have a hard winter. I suspect that the distribution of the broods through the year and the condition of the animal at the onset of hard frost are features which really determine whether a strain can live in a particular place or not. Though the truth of the suggestion cannot be tested by experiments in captivity, which at once introduce disturbances, I incline to the idea that _egeria_ has not got the right periodicity for northern climates. If it could arrange its life so that the population consisted either of young larvae, or perhaps of thoroughly formed pupae[11] at the onset of winter, it might, for any obvious reason to the contrary, be able to live in England. It is irregularly "polyvoltine," as the silk-worm breeders say, and as soon as a little warmth encourages it, a new generation starts into being, which if the frost comes at an untimely moment, is immediately destroyed. Many species are continually throwing off individuals which feed up fast[12] and emerge at once if the temperature permits, and I imagine a species of Satyrid wholly or largely represented by such individuals could scarcely survive in a country which had a hard winter. For such a climate some definite periodicity in the appearance of the broods may well be indispensable. But assuming that _egeria_ is cut off from cold climates for such a reason, there is nothing yet to connect these habits with the fulvous colour, and until breeding can be carried out on a satisfactory scale there is no more to be said. From time to time records appear of individual specimens more or less fulvous being caught in southern England, especially in the New Forest.[13] It would be interesting to know what offspring such individuals might produce. From the evidence now given some notion both of the strength and the weakness of the case considered as one of continuous climatic variation can be formed. I know no other equally satisfactory. Whether or not definite mixture of the intermediates with either of the extremes will be proved to occur, the case differs materially from those considered in the last chapter in the fact that at all events there is no general overlapping of forms. In a species so little given to wandering, overlapping could indeed scarcely be expected to occur. It is this circumstance which makes the species preeminently suitable as a subject for the study of climatic influences, and I trust that entomologists with the right opportunities may be disposed to explore the facts further. Just as many species, like _egeria_, have varieties which can be regarded as adapted to northern and southern regions, so there are also several which have lowland and Alpine forms quite distinct from each other. Every such case presents an example of the problem we have been considering. As the collector passes from the plains to the Alpine region, how will he find the transition from one form to the other effected? Does the lowland form give place to the Alpine form suddenly, with a region in which the two are mixed, or will he find a zone inhabited by an intermediate population? I have spent a good deal of time examining the facts in the case of _Pieris napi_ and its Alpine female variety _bryoniae_, and though there are many complications which still have to be cleared up, no doubt is possible as to the main lines of the answer. If in any valley in the Alps inhabited by both _napi_ and _bryoniae_ the collector catches every specimen he can, beginning at the bottom and working up to 7,000 feet, he will at first get nothing but _napi_. At about 2,500 feet, he may catch an occasional _bryoniae_ flying with the _napi_. After 3,000 feet _napi_ usually ceases, and only _bryoniae_ are found. As an exception a colony of _napi_ may be met with at much greater heights. I once found them in numbers at about 6,000 feet.[14] Not only were they free from any trace of modification in the direction of _bryoniae_, but they were of the thoroughly southern type of _napi_, being a late brood of that large and very pale kind (_meridionalis_) almost destitute both of dark veining above and of green veining below, which are common on the shores of Lago Maggiore and in other hot southern localities. Not far off at the same level were typical _bryoniae_ in fair abundance. Occasionally an intermediate may be met with. I have taken a few, for example, at Macugnaga and at Fobello. These, however, in my experience are rarities in the Alps. Fleck[15] gives notes on the distribution in Roumania which shows the same state of things. The lowland form is not transformed though found at great heights, and at Azuga (nearly 3,000 feet) _bryoniae_ occurs with only occasional "_flavescens_," viz., intermediates of the second brood. If this were all the evidence we should be satisfied that the lowland and Alpine types keep practically distinct, overlapping occasionally, but rarely interbreeding. The problem would remain, how is the distinctness of the two types maintained in the region of overlapping? Nowadays, I suppose, we should incline to answer this question by reference to segregation, and perhaps by an appeal to selective mating. The suggestion that segregation does take place is certainly true to some extent. There are, however, difficulties in the way, and the whole subject is one of great complexity. My own experiments were made in pre-Mendelian times and were not arranged with the simplicity which we now know to be essential. The results are neither extensive enough nor clear enough to settle the many collateral questions which have to be considered, and the work ought to be done again. Nevertheless, some notes of the observations may have a suggestive value. When I began, I did not sufficiently appreciate that the "_napi_" group, omitting the North American forms, and the Asiatic representatives, has at least three chief types in western Europe. The differences we have to deal with are manifested by the females only, so in this account particulars as to the males are omitted for the most part. These are (1) our own British _napi_; (2) the form found in the south, from the Loire downwards, and in the Italian Alps, which I think may be spoken of as _meridionalis_; (3) _bryoniae_, which is a form clearly recognizable in the _female_ only, and is found only in the arctic regions and in the Alps above 2,500 feet. The first two have several broods, two, three, or more, according to opportunity, and the first brood is different from the later ones. In _napi_ the markings on the upper surface are a dark grey but in _meridionalis_ they are a pale silvery grey and much less extensive. In the later broods of _napi_ there is much less general irroration of the veins, and the spots stand out as more defined and blacker. These differences vary greatly in degree of emphasis. In _meridionalis_ the later broods are entirely different from the first. Instead of having silvery markings they have the ground colour quite white, with the spots large and a full black. On the under side of the hind wings the usual green veins are almost absent, and I have seen individuals which could scarcely be distinguished from _rapae_. To these later broods the term _napaeae_ is sometimes applied, but I here use _meridionalis_ for the southern race in general as applicable to all broods. The female _bryoniae_ is totally unlike the others. The ground colour is a full yellow, and each nervure is thickly irrorated with a brown pigment often spreading so far as to hide the ground almost entirely in the fore-wings. The males corresponding with these females are not certainly distinguishable from those of our own _napi_. Both sexes have the green veining of the underside of the hind wing fully developed, rather more than is usual in the lowland races, but this is not really diagnostic of the variety. The first serious difficulty arises in regard to the second brood of _bryoniae_. It is stated that there is only one brood,[16] but I feel fairly sure that a second brood is sometimes produced, and that the females with a yellow ground and diminished irroration of the veins, not very uncommon in the Italian Alps in July to August, are generally representatives of it. Such insects would of course be classed with _bryoniae_ in collections. My experiments began with eggs of true _bryoniae_ females caught at about 2,500 feet early in July. These emerged in August-September as intermediates with yellow ground and about half as much black on the upper surface as _bryoniae_. They are exactly like the intermediates usually found in nature and in the light of later experience I regard them as natural F_{1} forms, and I think the mothers had been fertilised by _napi_ males, though I admit that in view of the rarity of natural intermediates there is a difficulty in this suggestion. Three of these females were mated with males raised from thorough _meridionalis_ females, and three families were produced. Two of them showed distinct evidence of segregation, some being yellow and some white with various intergrades, some being no blacker than _meridionalis_ and some ranging up to a dark intermediate type. Part emerged in the same autumn; and part overwintered, emerging as the spring _meridionalis_ or as the peculiar type which I afterwards learnt to know as the spring F_{1} form. The distinctions were fairly sharp between the several forms. But the offspring of the third female gave a series practically continuous from _meridionalis_ to the F_{1} type. The work of subsequent years gave results similarly irregular which could only be described adequately at great length. The outcome may however be summed up in the statement that there is evidence that both the yellow ground and the dark veining are due to factors, but that there are several of these and that imperfect segregation is not uncommon, producing various reduction-stages. The yellow ground may be due to one factor, and the several shades may be the result of irregularities in dominance, but the black markings when fully developed cannot I think be the result of less than three factors, one for the basal darkening, one for general irroration, and one for the margins. Probably also the enlargement of the spots is produced by a fourth factor. There was not, in my experience any great difficulty in getting the various forms to pair in captivity. Some attempts were made to see whether individuals of either type selected mates of their own type in preference to those of the other, but the results were inconclusive. There were some indications of such a preference; though, from the impossibility of judging how much of this may be due to other circumstances, I could not come to a positive conclusion on the rather meagre evidence. Recently Schima[17] has given a careful and detailed account of all the forms found in Lower Austria which he enumerates under 14 distinct varietal names. He gives full references to previous accounts, especially to the beautiful plates lately published by Roger Verity.[18] Examination of these and of my own specimens strongly suggests that the several forms are due to the recombination of the factors I have named. Among those which I have bred are representatives of most if not all the types enumerated by Schima in addition to other curious forms. For example I have _bryoniae_ markings on a ground practically white; the dark veins with spots almost obsolete; _meridionalis_ on a yellow ground; the intermediate amount of black on a white ground, etc. The last-named may occur wild and I have one from Macugnaga as well as one given me by Mr. F. Gayner from Lulea (Lapmark). To obtain really exact knowledge of the number of factors and their properties it would be necessary to repeat the work. After the beginning, I made a mistake in using British _napi_ instead of _meridionalis_ and the results were much confused thereby. The contrast between _meridionalis_ and the various dark forms is much greater and classification of the types would have been therefore easier. The British form is presumably _meridionalis_ plus the factor for the basal pigmentation. The problem is greatly complicated by the differentiation of the seasonal forms. The first point to be determined is whether _bryoniae_ is capable of producing a second brood when it is thoroughly pure-bred, and whether such a second brood is, as I suspect, normally intermediate in character. In the Alps generally there is no definitely intermediate population; nor I believe, is any such population met with in the north where the arctic _bryoniae_ meets _napi_, but as to this I have no precise information. One curious fact, however, must be mentioned, namely that there is a population that can probably be so described with fairness established at Mödling near Vienna. This is not in any sense an Alpine locality, and does not, as I am told, differ in any obvious way from the other suburbs of Vienna. Dr. H. Przibram was so good as to send me a set taken at this place, representing a second brood, and they were decidedly heterogeneous, ranging from an intermediate form such as _bryoniae_ fertilised by _napi_ usually produces, to a light yellowish second-brood type with little dark pigment. There are also two actual _bryoniae_. Whether true _napi_ also occur there I do not know, but I have no doubt they do. It would be well worth while to investigate the Mödling population statistically, and to breed from the intermediates which might not impossibly prove to be heterozygotes. There are also records of such intermediates being occasionally found in some parts of Ireland, in the north of Scotland, and in south Wales,[19] but I do not know of any regular colony of these forms. We can scarcely avoid the inference that one or more of the factors which make up _bryoniae_ may be carried by these intermediates. It is not clear why their interbreeding does not produce actual _bryoniae_ occasionally. If this occurred, the probability is that the fact would be known to collectors, at least in the British localities. The absence of true _bryoniae_ must, I think, be taken to mean that some essential factor is absent from these intermediates. To sum up the evidence, the facts that are clear may be thus enumerated: 1. _Napi_ and _bryoniae_, or in the Italian Alps, _napaeae_ and _bryoniae_ frequently meet each other. 2. They cross without difficulty, producing fertile offspring. 3. But in the levels at which they overlap there is no intermediate population, and only occasional intermediate individuals. 4. In certain parts of the distribution of _napi_ similar intermediates sometimes occur, and at one place (Mödling) they are so frequent as apparently to constitute a colony. 5. As to the genetic relations of the two forms there is no complete certainty. Indications of segregation have been observed in some cases, but there are several factors concerned and they are liable to some disintegration. Another form in which I tried to investigate the same problem is _Coenonympha arcania_, which has one Alpine form known as _darwiniana_, and another, _satyrion_. In calling _satyrion_ a form of _arcania_ I follow Staudinger and other authorities, but I have never been quite satisfied that it should be so regarded. The differences between _arcania_ and _darwiniana_ are essentially differences of degree; _C. arcania_ occurs in places where there is cover, and reaches up the valleys usually as high as the mixed woods of deciduous trees, which is about 2,500 feet. The variety _darwiniana_, on the contrary, is an insect of treeless hillsides, and I regard it as a dwarf and possibly a stunted form. It would not greatly surprise me to find that with the application of good conditions _arcania_ could be raised from _darwiniana_ eggs, or that if _arcania_ larvae were starved they might give rise to _darwiniana_ butterflies. I have been unsuccessful in trying to rear the species, having lost the larvae by disease. Usually one does not catch _arcania_ and _darwiniana_ on the same ground, and as _Festuca ovina_--a typically hill-side grass--is a common food-plant of _darwiniana_ there can be little doubt that _arcania_ feeds on some other grass, probably woodland species. Colonies of _arcania_ of varying size and brightness are commonly found, and though a sample of _arcania_, finely grown, from a warm Italian wood, presents a striking contrast with _darwiniana_ from an Alpine pasture, one certainly may get samples which fill all the gradations. Generally the sample from a given locality is fairly homogeneous. Of _satyrion_ I have little personal experience. I only twice found it, namely at Zinal, and at Hallstatt in Austria, but it occurs at Zermatt, Arolla, and in several Swiss localities above 5,000 feet, and I understand that it is the typical Alpine form in the Engadine. With its darkened colour and reduced size it might well be expected to be a still further stunted form of _darwiniana_. Yet I have never found the one succeed to the other at the higher levels. If _darwiniana_ appears when Alpine conditions are reached in a valley it will be met with up to the highest level at which such butterflies live. Tutt was of opinion that _satyrion_ is a distinct species.[20] I once, at the top of the Vorderrheinthal caught a sample of _darwiniana_ a few of which (males) were so dark and had the eye spots so poorly developed that they looked like transitions to _satyrion_. Otherwise I never found any such transitional forms and they are certainly exceptional. There is further a record[21] of _satyrion_ having been taken flying with _arcania_. This was near Susa, at about 2,000 feet I infer. Mr. H. E. Page has similar specimens from Caud and from St. Anton (Arlberg). The females, however, both of mine and of Mr. Page's samples are a pale brown, quite unlike the females both of _arcania_ and of the dark Zinal _satyrion_. The difficulty thus raised has not I think yet been considered by the authorities, and it is possible that the Alpine forms of _arcania_ are in reality three, not two. The evidence taken together suggests, I think, that _darwiniana_ is related to _arcania_ much as so many of the Alpine varieties of plants are to the well-developed individuals of the lower levels. I do not anticipate that factorial differences will be found in these insects, and it is by no means impossible that the distinctions between them are the direct consequences of altered conditions. The relations of _arcania_ to _satyrion_ are more doubtful, and in that case a factorial difference may at least be suspected. The species of the genus _Setina_ have Alpine forms which agree in possessing a characteristic extension of the black pigment to form radiating junctions between the spots on the wings. Speyer, who discussed the interrelations of these forms in detail,[22] lays stress on the absence of genuine transitional forms between _aurita_ and the variety _ramosa_. Both are mountain insects but _ramosa_ extends to levels higher than that at which _aurita_ ceases, which is about 4,000 feet. The two forms are often found flying together. Speyer says that his brother searched diligently for transitional forms at the level of overlapping, but found none, so that at least they may be regarded as rare. The variety _ramosa_ is not infrequent at much lower levels (_e. g._, Chiavenna, 1,020 feet; Reussthal, 1,500 feet) and extends as high as the permanent snows. In the British Museum collection, however, I have seen several that I should regard as transitional. Speyer perhaps would have classed as _ramosa_ all in which the spots of the central field were united, and it is by no means unlikely that breeding would prove such individuals to be heterozygous.[23] There can scarcely be a doubt that the distinction between _aurita_ and _ramosa_ is factorial, the radiate _ramosa_ probably having the factor for striping. In support of this view may be mentioned the observation of Boisduval,[24] respecting a gynandromorphous individual, which was _aurita_ male on one side, and _ramosa_ female on the other. Speyer makes another excellent comment. He points out that the simple notion that the radiation is a mere extension of pigmentation consequent on the climate of the higher levels, will not fit the facts very easily, because the size of the spots varies greatly in _aurita_ itself at any level, and lowland specimens may actually have more black confined to the spots alone than some _ramosa_ possess on spots and lines combined.[25] The two Salamanders, _S. maculosa_ and its Alpine form _atra_, might not improbably furnish evidence bearing on the same problem. The two are of course very distinct, not merely in colour (_maculosa_ being spotted with yellow or orange while _atra_ is entirely black) but also in the mode of reproduction, a feature to which reference will be made in the next chapter. I cannot, however, find any evidence as to the overlapping of the two forms. _S. atra_ occurs from about 3,000 feet or somewhat less, and reaches great elevations in the Eastern Alps, but I do not know if the two forms ever occur in the same localities. Leydig,[26] Boulenger,[27] and most modern authorities regard the two types as distinct species, but they are in any case closely allied, and it would be of interest to have exact knowledge of their geographical delimitations. The reader who has considered the cases adduced will appreciate the difficulties which must be faced in any attempt to account for the facts in a rational way. As always in a problem of Evolution, two separate questions have to be answered. First how did the form under consideration come into existence, and secondly, how did it succeed in maintaining itself so as to become a race? The evidence from the local forms, though very far from giving complete answers to either of these questions definitely refutes the popular notion that a new race comes into existence by transformation of an older race. If a gradual mass-transformation of this kind took place we should certainly expect that when two types, nearly allied and capable of interbreeding, overlap each other in their geographical distribution, a normally intermediate population would exist. If each type can maintain itself, and if each came into existence by gradual transformation, then there must have been an intermediate capable of existing and maintaining itself as a population; and if this had ever been, surely in the region of overlapping, that intermediate population should continue. Especially should such a population be found when the two extreme types are adaptational forms and the region of overlap is a region of intermediate conditions. But of the examples we have examined there is only one, that of _Pararge egeria_ and _egerides_, which can at all be so interpreted, and even in that case it is not impossible that more minute observation would reveal discontinuity between the extremes and the admittedly normal intermediate population. Granting provisionally however that this example, as it stands, is consistent with the conventional theory of evolution, I know not where we should look for another case equally good. When the distinctions are produced by direct influence of conditions operating during the lifetime of the individuals, examples of intermediate populations occupying the areas of intermediate conditions can no doubt be produced. Many turf-like Alpine plants, for instance, if protected from exposure and properly nourished can grow as large as those of the same species found in the valleys, and in the case of such quantitative effects, intermediate conditions can doubtless produce intermediate characters. Even these examples however are not very abundant, and often the intermediate locality has not a form intermediate between those of the two extreme localities, but some third form distinct from either. This is the case for instance in the fauna of brackish waters. We are taught to believe that the fresh water fauna was evolved from the marine fauna, which it well may have been; but as students of Crustacea and Mollusca know familiarly, the brackish water forms are not as a rule intermediates between fresh water species and sea species, but more usually they are special forms belonging to the brackish waters, with the peculiar property that they can tolerate a great range of conditions, and live without ostensible variation in waters of most various compositions and densities, which very few marine or fresh water species are able to do. Sometimes the distinction between local races, as in _Rhamphocoelus passerinii_ and _icteronotus_ may be regarded with confidence as due to one simple Mendelian factor possessed by one race and absent from the other, but I think, more often, as in _Colaptes_ or in the varieties of _Pieris napi_, the existence of several distinct factors is to be inferred. As we have seen, the races of _Colaptes_ show almost beyond doubt that in different areas at least three distinct factorial combinations can be perpetuated as races. In the distribution of variability we find, I think, some hint as to the steps by which the phenomena under consideration have come to their present stage, and I am disposed to regard the facts so well attested in the case of our own melanic moths as a true indication of the process. Following this indication we should regard the change in the character of a population as beginning sporadically, by the appearance of varying individuals, possibly only one varying individual, in, it may be, one place only. As to _why_ a variety should increase in numbers we have nothing but mere speculation to offer, and for the present we must simply recognise the fact that it may. That such survival and replacement may reasonably be taken as an indication that the replacing race has some superior power of holding its own I am quite disposed to admit. Nevertheless it seems in the highest degree unlikely that the outward and perceptible character or characters which we recognise as differentiating the race should be the actual features which contribute effectively to that result. In discussions of geographical distribution in relation to problems of origin it is generally said that very nearly allied species usually occupy distinct areas, while other competent observers state the exact contrary. Lately, for example, Dr. R. G. Leavitt[28] has published an important collection of evidence upholding the latter proposition, taken chiefly from the botanical side, showing how in numerous genera two or more closely allied species coexist, frequently without intermediates, in the same localities, and may even be thus found in company throughout their distribution. The difference of opinion evidently arises from a confusion as to the sense in which the term "species" is understood and applied. Leavitt, for example, is avowedly following Jordan and, among moderns, Sargent, in applying a close analysis, and denoting as species all forms which are distinct and breed true. Against this use of the term I know no valid objection[29] but it must be obvious that if others follow a different practice confusion may result when observations are summarised in general statements. We will consider this subject again in another place, but here it may be sufficient to say that there can scarcely now be a doubt that numbers of these associated species, such as Jordan discriminated, represent various combinations of the presence and absence of Mendelian factors. This does not in any way weaken the argument which Leavitt founds upon the facts, namely, that the observed distribution of these forms is consistent with the supposition of an evolution largely discontinuous. On the other hand, those who have come to the opinion that nearly allied species generally occupy distinct ground are presumably more impressed by the characters differentiating the geographically distinct or adaptational races, seeing that genuine intermediates between them are less commonly found. Those geographical races may no doubt contain various differentiated forms; but when all live together, occasional intermediates are usually to be found even in the case of characters habitually segregating. These segregating forms Jordan would certainly have determined as species, and it must be conceded that no physiological definition has yet been drawn which consistently excludes them. FOOTNOTES: [1] Often referred to by older writers as _Meone_, Esper's name. [2] There are also two distinct island forms, unlike the European, _Xiphia_ of Madeira, and a smaller variety, _Xiphioides_ of Canary. See especially, Baker, G. T., _Trans. Ent. Soc. London_, 1891, p. 292. [3] Speyer, Adolf, and August. _Verbreitung der Schmetterlinge_, 1858, I, p. 217. [4] _Lepid. Comparée_, fsc. III, p. 372. [5] Mr. Rowland-Brown has called my attention to a statement by Dr. Vaillantin (_Petites Nouv. Ent._, II, 235) that in Indre-et-Cher the first brood is of the northern type and the second of the southern. My experience is that in captivity these distinctions do not occur, and I have true _egeria_ as first brood from Vienne and as the late brood from the Landes. I never collected in Indre-et-Cher. [6] I have since seen true _egeria_ from Ferrol in the extreme northwest, which was in Mr. Tutt's collection. [7] Mr. G. Wheeler kindly showed me a series identical with this type, from Guernsey, and others from near Laon. [8] _Ent. Rec._, V, 1894, p. 134. [9] Mr. Wheeler has some pale but rather worn specimens from the Rhone Valley at Vernayaz. [10] See Fleck, E., Die Macrolep. Rumäniens, _Bul. Soc. Sciinte_, VIII, 1899, p. 720. [11] My experience agrees with that of Mr. H. Williams (_Ent. Rec._, VIII, 1896, p. 181) that pupae, well-formed, can stand considerable frost; but I used to find that half-grown larvae usually died if unprotected, and I believe that larvae which attempted to pupate in warm autumn weather and then got caught by frosts, always died. Small larvae which can creep into shelter at the bottom of the plants survived, and I expect that in the north the winter is usually passed in that state (see also Merrifield, F., _Ent. Rec._, VIII, 1896, p. 168, and Carpenter, J. H., _ibid._). [12] Some most unlikely species do this. I once had a larva of _Parnassius delius_, found at about 5,500 feet, which emerged late in the autumn (in October I believe), a season at which it must have perished in its own country. [13] See, for examples, Barrett, G. C., _Lepidoptera of the Brit. Islands_, I, 1893, p. 229; also Grover, W., _Ent. Rec._, IX, 1897, p. 314; Williams, H., _Proc. Ent. Soc._, 1898, who reared several specimens from the New Forest which would pass for Bretons, though the rest of the family were true _egerides_. [14] Above the Tosa falls. [15] _Bul. Soc. Sciinte_, VIII, 1899, p. 691. [16] The fact that Weismann by heating pupæ obtained only one autumn specimen seems to me to show rather that a second brood can be produced than that it cannot, which is the inference usually drawn. [17] Schima, K., _Verh. Zool. bot. Ges. Wien_, LX, 1910, p. 268. [18] _Rhopalocera Palaearctica_, Florence, 1905-11, especially Pl. XXXII. [19] See figures in Barrett, G. C., _Lepidoptera of Brit. Islands_, I, pt. 3, p. 25. [20] Tutt, J. W., _Ent. Rec._, XVIII, 1905, p. 5. In the same place he states that on the Mendel Pass _arcania_ "runs into" _darwiniana_ and that in the Tyrolean localities the transition is especially evident. Wheeler (_ibid._, XIII, 1901, p. 121) expresses the contrary opinion, that _satyrion_ does grade to _arcania_. [21] H. Rowland-Brown, _Ent. Rec._, XI, 1899, p. 293. [22] Speyer, Stettiner, _Ent. Ztg._, XXXI, 1870, p. 63. [23] In regard to the closely analogous case of _Spilosoma lubricipeda_, Standfuss makes a similar statement. He bred the type on a large scale with the radiate form which he calls _intermedia_, and says that in four years of miscellaneous crossing he never obtained really transitional forms. Nevertheless after examining large series, especially those of Mr. W. H. B. Fletcher, I came to the conclusion that several might be so classed, but I am quite prepared to find that such specimens are heterozygous. (See Standfuss, _Handb. d. Gross-Schmet._, 1896, p. 307.) It is by no means unlikely that various dark forms of _lubricipeda_ correspond with a progressive series of factorial additions. Many of the stages have been named, and of these the most definite are the _intermedia_ of Standfuss (probably = _eboraci_ of Tugwell) and the very dark _Zatima_ of Heligoland, in which only the thorax, the nervures and a small field in the fore-wings remain yellow. A form was bred by Deschange from _Zatima_ in which even the field in the forewing is obliterated. The exact circumstances in which _Zatima_ occurs in Heligoland would be worthy of special investigation, for the normal _lubricipeda_ is also found on the island. For references as to the British occurrences see especially, Hewett, W., _Naturalist_, 1894, p. 353. As to _Zatima_ see especially Krancher, _Soc. Ent._, II, 1887-8, p. 26. I am indebted to Dr. Hartlaub for information as to the Heligoland types. [24] Boisduval, _Bull. Soc. Ent. Fr._, III, 1834, p. 5. [25] The systematics of _Setina_ have been much controverted, but no one I believe doubts that _aurita_ and _ramosa_ are forms of one species. See also Chapman, A. T., _Ent. Rec._, XIII, 1901, p. 139. [26] _Arch. Naturg._, 33, 1867, p. 116. [27] _Brit. Mus. Cat., Batrachia Gradientia_, 1882. [28] The Geographical Distribution of nearly related Species. _Amer. Nat._, XLI. 1907, p. 207. [29] See later, p. 242. CHAPTER IX THE EFFECTS OF CHANGED CONDITIONS: ADAPTATION In the attempt to conceive a process by which Evolution may have come about, the first phenomenon to be recognized and accounted for is specific difference. With that recognition the outline of the problem is defined. The second prerogative fact is adaptation. Forms of life are _on the whole_ divided into species, and these species _on the whole_ are adapted and fit the places in which they live. To many students of Evolution, adaptation has proved so much more interesting and impressive than specific diversity that they have preferred it to the first place in their considerations. Whether this is, as I believe, an inversion of the logical order or not, there is one most serious practical objection to such preference, that whereas specific diversity is a subject which can be investigated both by the study of variation and by the analytical apparatus which modern genetic science has developed, we have no very effectual means of directly attacking the problems of Adaptation. The absence of any definite progress in genetics in the last century was in great measure due to the exclusive prominence given to the problem of Adaptation. Almost all debates on heredity centered in that part of the subject. No one disputes that the adaptation of organisms to their surroundings is one of the great problems of nature, but it is not the primary problem of descent. Moreover, until the normal and undisturbed course of descent under uniform conditions is ascertained with some exactness, it is useless to attempt a survey of the consequences of external interference; nor as a rule can it be even possible to decide with much confidence whether such interferences have or have not definite consequences. Those, for example, who debated with enthusiasm whether acquired characters are or are not transmitted were constantly engaged in discussing occurrences which we now know to be ordinary features of descent under uniform conditions, and the origin of variations which were certainly not caused directly by circumstances at all. In the absence of any factorial analysis, or of any conception of what factorial composition means and implies, no one knew what varieties might be expected from given parents. The appearance of any recessive variety was claimed as a consequence of some treatment which might have been applied to the parents. There was no possible standard of evidence or means of controlling it, and thus the discussion was singularly unfruitful. Before we can tell how the course of descent has departed from the normal, we must know what the normal would have been if we had let alone. We are still far from having such knowledge in adequate measure, but it does now exist in some degree, and we are steadily approaching a position from which we shall be able to form fairly sound estimates of the true significance of evidence for or against the proposition that environmental treatment can produce positive disturbances in the physiological course of descent. Thus described, the field for consideration is very wide. Though the effects of changed conditions were especially studied in the hope of solving the problem of adaptation by direct observation, that, as all are now agreed, is but a part of a more general question. We must ask not only do changed conditions produce an _adaptative_ response on the part of the offspring, but whether they produce any response on the part of the offspring at all. It is not in doubt that by violent means, such as starvation or poisoning of the reproductive cells, effects of a kind, stunting and deformity for instance, can be made evident, just as similar effects may follow similar treatment during embryonic or larval life. Apart from interferences of this class, are there any that may be reasonably invoked as modifying the course of inheritance? No epitome of the older evidence for the inheritance of adaptative changes is here required. That has often been collected, especially by Weismann, who exposed its weaknesses so thoroughly as to carry conviction to most minds, and showed that whether the phenomenon occurs or not, no one can yet prove that it does. Belief in these transmissions, after being almost universally held, was with singular unanimity abandoned. This change in opinion, though doing credit to the faith of the scientific community in evidential reasoning, is the more remarkable inasmuch as the strength of the idea was not derived from the minute amounts of supposed facts now demolished. On the contrary, it was really an instinctive deduction from a wide superficial acquaintance with the properties of animals and plants. They _can_ accommodate themselves to circumstances. They _do_ make responses sometimes marvellously appropriate to demands for which they can scarcely have been prepared. What more natural than to suppose that the permanent adaptations have been achieved by inherited summation of such responses? No one had actually been driven to believe in the inheritance of adaptative changes because bitches which had been docked had been known to give birth to tailless puppies, or because certain wheat in Norway was alleged to have become acclimatized in a few generations. Evidence of this kind was collected and produced rather as an ornamental appendix to a proposition already accepted, and held to be plainly demonstrated by the facts of nature. Looked at indeed in that preliminary and uncritical way, the case is simply overwhelming. Those who desire to see how strong it is should turn to Samuel Butler's _Life and Habit_, and even if in reading they reiterate to themselves that no experimental evidence exists in support of the propositions advanced, the misgiving that none the less they may be true is likely to remain. Making every deduction for the fact that the wonders of adaptation have been grossly exaggerated, and that marvels of fitness and correspondence between means and ends have grown out of mere anthropomorphic speculations, there is much more left to be accounted for than can at all comfortably be accepted as the product of happy accidents. So oppressive are these difficulties that we can scarcely blame those who imagine that the study of heredity is primarily directed to the problem of the transmission of acquired characters, a preconception still almost universal among the laity. But since the belief in transmission of acquired adaptations arose from preconception rather than from evidence, it is worth observing that, rightly considered, the probability should surely be the other way. For the adaptations relate to every variety of exigency. To supply themselves with food, to find it, to seize and digest it, to protect themselves from predatory enemies whether by offence or defence, to counter-balance the changes of temperature, or pressure, to provide for mechanical strains, to obtain immunity from poison and from invading organisms, to bring the sexual elements into contact, to ensure the distribution of the type; all these and many more are accomplished by organisms in a thousand most diverse and alternative methods. Those are the things that are hard to imagine as produced by any concatenation of natural events; but the suggestions that organisms had had from the beginning innate in them a power of modifying themselves, their organs and their instincts so as to meet these multifarious requirements does not materially differ from the more overt appeals to supernatural intervention. The conception, originally introduced by Hering and independently by S. Butler, that adaptation is a consequence or product of accumulated _memory_ was of late revived by Semon and has been received with some approval, especially by F. Darwin. I see nothing fantastic in the notion that memory may be unconsciously preserved with the same continuity that the protoplasmic basis of life possesses. That idea, though purely speculative and, as yet, incapable of proof or disproof contains nothing which our experience of matter or of life at all refutes. On the contrary, we probably do well to retain the suggestion as a clue that may some day be of service. But if adaptation is to be the product of these accumulated experiences, _they must in some way be translated into terms of physiological and structural change_, a process frankly inconceivable. To attempt any representation of heredity as a product of memory is, moreover, to substitute the more obscure for the less. Both are now inscrutable; but while we may not unreasonably aspire to analyse heredity into simpler components by ordinary methods of research, the case of memory is altogether different. Memory is a mystery as deep as any that even psychology can propound. Philosophers might perhaps encourage themselves to attack the problem of the nature of memory by reflecting that after all the process may in some of its aspects be comparable with that of inheritance, but the student of genetics, as long as he can keep in close touch with a profitable basis of material fact, will scarcely be tempted to look for inspiration in psychical analogies. For a summary of the recent evidence I may refer the reader to Semon's paper[1] where he will find a collection of these observations described from the standpoint of a convinced believer. At the outset one cannot help being struck by the fact that of the instances alleged, very few, even if authentic, show the transmission of acquired modifications which can in any sense be regarded as adaptative, and many are examples not so much of a transmission of characters produced in the parents as of variation induced in the offspring as a consequence of treatment to which the parents were submitted, the parents themselves remaining apparently unmodified. No one questions the great importance of evidence of this latter class as touching the problem of the causes of variation, but it is not obvious why it is introduced in support of the thesis that acquired characters are inherited. It is most difficult to form a clear judgment of the value of the evidence as a whole. To doubt the validity of testimony put forward by reputable authors is to incur a charge of obstinacy or caprice; nevertheless in matters of this kind, where the alleged phenomena are, if genuine, of such exceptional significance, belief should only be extended to evidence after every possible source of doubt has been excluded. We believe such things when we must, but not before. At the very least we are entitled to require that confirmatory evidence should be forthcoming from independent witnesses. So far as I have seen, this requirement is satisfied in scarcely any of the examples that have been lately published, and until it is, judgment may reasonably be suspended. In some cases, however, the facts are not doubtful. Standfuss, by subjecting pupae of _Vanessa urticae_ to cold, produced the now well-known temperature-aberrations in which the dark pigment is greatly extended. He put together in a breeding-cage 32 males and 10 females showing this modification in various degrees. Two of these females died without leaving young. Seven produced exclusively normal offspring. From the eighth female 43 butterflies were bred, and of these there were four (all males) which to a greater or less extent exhibited the aberrational form.[2] The mother of this family was the most abnormal of the 10 females originally put in. Fischer's experiment with _Aretia caja_ was on similar lines. From pupae which had been frozen almost all the moths which emerged showed aberrational markings. A pair of these mated and produced 173 young which pupated. Those which emerged early were all normal, but of those which emerged late, 17 had in various degrees abnormal markings like those of the parents.[3] In neither of these examples is there any question as to the facts. Both observers have great experience and give full details of their work. As regards _Vanessa urticae_, however, it must be recalled that Fischer himself showed that in Nymphalids somewhat similar aberrations could be produced both by heat and by cold, and even by centrifuging the pupae. Frl. von Linden produced a transitional form of the same aberration in _V. urticae_ by the action of carbonic acid gas.[4] It is highly probable that the appearance is due to a morbid change, perhaps an arrest of development, which may be brought about by a great diversity of causes. In the experiments the cause probably was a diseased condition of the tissues of the mother herself. She had been subjected to freezing sufficiently severe to prevent the proper development of the pigments and some of the ovarian cells presumably suffered also. It will be observed that the only specimens which were affected were the offspring of the most abnormal female, and of them only four out of forty-three showed any change. The same interpretation probably applies to the cases in _Arctia caja_. In this species the markings are well known to be liable to great variation. As Barrett says, even in nature individuals are rarely quite alike, and an immense number of strange forms occur in collections.[5] These are greatly sought after by some collectors, especially in England, where they fetch high prices at auctions, and it is notorious that most of them come from Lancashire and the West Riding of Yorkshire. It is commonly supposed that the breeders of that district subject them to abnormal conditions, and especially to unnatural feeding, but I know no clear evidence that this is true. From whatever cause it is certain that the natural pattern is, in some strains at all events, very easily disturbed. The elaborate experiments of Schröder with _Abraxas grossulariata_ are difficult to follow and are complicated by the fact that the series which was submitted to abnormal temperatures was derived from an abnormal original pair. From the evidence given it is not clear to me whether the temperature had a distinct effect. This insect, like _Arctia caja_, produces an immense number of variations (especially in the amount of the black pigment) and as most of these are, I believe, reared in domestication for sale, it is highly probable that the species is easily influenced by cultural conditions. Schröder describes two other experiments which have been accepted by Semon and other supporters of the view that acquired characters are transmitted. In the first, _Phratora vitellinae_, a phytophagous beetle living on the undersides of leaves, was used. It naturally feeds on _Salix fragilis_, a species without a felt, or tomentum, on the underside of the leaves. Larvae were transferred to another willow (near _S. viminalis_) which has the undersides of the leaves felted. The larvae took readily to the new food, pushing the tomentum before them as they gnawed the leaves. They came to maturity and when they were about to lay their eggs they were given a free choice between _S. fragilis_ and the tomentose species. The greater number of ovipositions, 219, took place on _fragilis_, and there were 127 on the tomentose bush, which we are told was six times as large as the _fragilis_. The larvae from _fragilis_ were next put on the tomentose species and reared on it. When they became imagines they were similarly given their choice, with the result that there were 104 ovipositions on the tomentose species and only 83 on _fragilis_. In the next generations there were 48 ovipositions on the tomentose and 11 on _fragilis_. Finally the fourth generation made 15 ovipositions on the tomentose and none on _fragilis_. The difficulty about such experiments is obviously that one has no assurance that the change of instinct, in so far as there is any, may not be a mere consequence of the captivity. It must, besides, be extremely difficult to arrange the experiment so that there is really an equal choice between the two bushes, when one stands beside the other. Przibram, in quoting this case, considers that as the tomentose bush was about six times as large as the _fragilis_, some indication of the relative attractiveness of the two may be obtained by dividing the ovipositions on the larger bush by six, but I imagine the matter must be much more complex. Schröder's second example is not more convincing, in my opinion, though Semon regards it as one of the most important pieces of evidence. It concerns a leaf-rolling moth, _Gracilaria stigmatella_, the larva of which is said normally to make its house by bending over the _tips_ of the sallow leaves on which it feeds. Schröder placed larvae on leaves from which the tips had been cut, and these larvae made their houses by rolling over the _sides_ of the leaves. Their offspring were again fed on leaves without tips, and as before, they rolled in the leaf-margins either on one side or both. The offspring of this second generation were then fed on entire leaves. There were 19 houses made by these (?19) larvae, and of them 15 were normal, made by folding down the tips of the leaves, while 4 were abnormal, made by rolling in the leaf-margins. Schröder says that in nature he has only twice seen abnormal houses; but it is clearly essential not only that the frequency of such variability in nature should be thoroughly examined, but also that we should know whether when the species is bred in captivity these irregularities of behaviour do or do not occur when the larvae are fed on uninjured leaves. The famous case of Schübeler's wheat is revived by Semon. The story will be familiar to most readers of the literature of the subject. Briefly it is that annuals, especially wheat and maize, raised from seed in Central Europe take more time in coming to maturity and ripening than similar plants raised in Norway, where the summer days are much longer. The received account is that he imported seed especially of maize and of wheat from Central Europe to Norway and found that in successive years the period of growth and ripening was increasingly reduced. After two generations seed of the accelerated wheat was sent back to Breslau where it was grown, and was found to ripen rather more slowly than in Norway, but much more quickly than the original stock had done. The facts recorded by Schübeler[6] are that he received seed from Eldena, which is on the Baltic near Greifswald. The variety is described as "_100 tägiger Sommer Weizen_," but no more exact record of its behaviour in Germany is given. This wheat, grown at Christiania in 1857, took 103 days to harvest. Its seed was again grown in Christiania in 1858, and took 93 days, and sown again in 1859 it took only 75 days, 28 days less than in the first year of cultivation in Norway. Seed of the 1858 crop was sent to Breslau, and grown there by Roedelius in 1859; it took 80 days. Evidently before such a record can be used as proving an inheritance of acquired characters numbers of particulars should be forthcoming. The view that Johannsen has taken is that the result was probably due to unconscious selection of the earlier individuals among a population consisting of many types of various compositions. Some effect may no doubt be ascribed to that cause, but I cannot think that alone it would account for the results. My impression is rather that they were produced by differences in the cultivation and especially in the seasons. Research of an elaborate character would be necessary in order to eliminate the various sources of error, and nothing of the kind has been done; nor does Semon allude to these difficulties in prominently adducing Schübeler's evidence. A difference of even three weeks in time of harvesting may easily be due to variation in the season. It would in any case be difficult to analyse the meteorological conditions, and to decide how much effect in postponing or accelerating the harvest might be due to cold days, to cloudy days, to wet weather, to fluctuations in average temperature, to hot days, and other such incidents occurring at the different periods of growth, even if they were specially watched while the experiments were in progress, and at this distance of time such analysis is practically impossible. Without careful simultaneous control-experiments this evidence is almost worthless. The director of the Meteorological Office[7] has, however, kindly sent me some details of the weather at Breslau from 1857 to 1860, and I notice that as a matter of fact July, 1859, was an exceptionally hot month, _having an average of 2.67° C. above the mean_ for the twenty years 1848-1867. June in that year was slightly (0.31° C.) below the mean and May slightly above it (0.18° C.). August was also abnormally hot, 2.35° C. above the average. The Breslau wheat was sown on _May 19_ and harvested on August 6. There was a cold spell from May 11 to 14, which this wheat escaped, as it was sown on May 19. In the other years the cold spell came much later. These elements of the weather may possibly have done something to hurry the ripening in 1859. It unfortunate that we are not told how long similar wheat from Breslau seed took to ripen in that year. As regards the Norway cultivations we have the average monthly temperatures recorded by Schübeler, though he does not discuss them in connection with this special problem. It is quite clear that 1857, in which the period was 103 days, was an exceptionally cold summer, especially as regards the months of June and July, but though there was, so far as the temperature records go, no great difference between 1858 and 1859, the year 1859, in which the period of ripening was the shortest, was somewhat colder in Norway than 1858. But we have the further difficulty that there were ten days difference in sowing, for in 1858 the sowing was made on May 14, and in 1859 on May 24. With all these possibilities uncontrolled, and indeed unconsidered, I am surprised that Semon should claim these experiments as one of the chief supports for his views. Schübeler's other allegations respecting the influence of climate on plants grown in various places and especially at different elevations in Norway have been destructively criticised by Wille[8] to whose paper readers interested in the subject should refer. Before the appearance of Wille's criticisms Wettstein[9] made a favourable reference to Schübeler's work, accepting his conclusion. He states also that he has himself made analogous experiments with flax, finding that the length of the period of development and a series of morphological characters show an adaptation to local conditions, and that on transference of seed to other conditions the previous effects are maintained. No details, however, are given, and I do not know if anything more on the subject has appeared since. The other examples cited by Wettstein, such as the observations of Cieslar on forest-trees and those of Jakowatz on gentians seem to me open to all the usual objections applicable to evidence of this kind. Such work, to be of any value for the purpose to which it is applied, must be preceded by a study of the normal heredity and of the variations of the species. Most of the recent writers (Semon, Przibram, etc.) on the inheritance of acquired characters accept the story of Brown-Séquard's guinea pigs, which are said to have inherited a liability to peculiar epileptiform attacks induced in their parents by various nervous lesions. The question has been often debated and several observers have repeated the experiments with varying results, some failing to confirm Brown-Séquard, others finding evidence which in various degrees supported his conclusions. Recently a new and especially valuable paper has been published by Mr. T. Graham Brown[10] which goes far towards settling this outstanding question. He states that "the Brown-Séquard phenomenon is nothing more or less than a specific instance of the scratch-reflex," and it is due to a raised excitability of the mechanism of this reflex. This raised excitability is the character acquired as a consequence, for instance, of the removal of part of one great sciatic nerve. The nature of this raised excitability and its causation are discussed and elucidated, but this part of the work is not essential to the present consideration. Mr. Graham Brown in his summary of conclusions remarks that it is very difficult to see how this condition of raised excitability can be transmitted to the offspring, and this comment which might be made in reference to any of the alleged cases certainly applies with special cogency to the present example. He then calls special attention to three observations: 1. That guinea pigs which had a "trophic" change in the foot, as a result of division of the great sciatic nerve, have repeatedly been seen to nibble the feet of other guinea pigs which had this change in the foot from the same causes. 2. That accidental injury to the toes may be followed by the Brown-Séquard phenomenon in an otherwise normal animal. 3. That in several instances the young of guinea pigs which exhibited the phenomenon have been noticed to have one or more toes eaten off by the mother. Brown-Séquard noticed that almost all his animals in which the great sciatic was divided acquired the "epilepsy" and nibbled those parts of their feet in which sensation had been lost. Of the offspring of such animals he found that a very small proportion exhibited a malformation of the feet, and of these some showed the "epilepsy." The proportion which showed the "epilepsy" was one to two per cent. of the offspring. Morgan[11] is quoted by Graham Brown as having suggested that the loss of toes in the offspring may have been due to mutilation by the mother, following his experience in a case in which the tails of mice in succeeding litters were thus devoured, and there can be little doubt that in this suggestion lies the clue to the explanation of the whole mystery. Graham Brown concludes that it may be supposed with every degree of probability that the "transmission" was due to injuries inflicted upon the young by their parents. With this conclusion most people will now be disposed to agree, and we may hope that we shall hear the last of this curious myth--to the elucidation of which a vast quantity of research has been devoted. The series of experiments made by Kammerer with various Amphibia have attracted much attention and have been acclaimed by Semon and other believers in the transmission of acquired characters as giving proof of the truth of their views. With respect to these observations the chief comment to be made is that they are as yet unconfirmed. Many of the results that are described, it is scarcely necessary to say, will strike most readers as very improbable; but coming from a man of Dr. Kammerer's wide experience, and accepted as they are by Dr. Przibram, under whose auspices the work was done in the Biologische Vesuchsanstalt at Vienna, the published accounts are worthy of the most respectful attention. The evidence relates chiefly to three distinct groups of occurrences: 1. Modification in _Alytes obstetricans_, the Midwife Toad, affecting both the structure and the mode of reproduction, induced by compulsory change of habits. 2. Modification in the mode of reproduction of _Salamandra atra_ and _maculosa_ induced by compulsory change of habits. 3. Modification in the colour of _Salamandra maculosa_ induced by change in the colour of the soil on which the animals were kept. 1. I will take first the case of _Alytes_,[12] because it is the most definite example, and because it is the case which most readily admits of repetition and verification. The habits of _Alytes obstetricans_ are well known. The animals copulate on land. As the strings of eggs leave the female they are entangled by the hind legs of the male, and being adhesive they stick to him and undergo their development attached to his back and legs. The number of eggs varies from 18 to 86, a number much smaller than is usual in toads and frogs which lay their eggs in water. The eggs are large and full of yolk. There are two breeding seasons, one about April and the other about September, and a winter hibernation. Not only animals brought in from outside, but their offspring reared in domestication maintain these normal habits in confinement, if the temperature does not exceed 17° C. (pp. 499 and 534). If, however, the temperature be artificially raised and kept at 25-30° C., the males do not attach the eggs to themselves when spawning occurs on land but let them lie. The adhesion of the eggs is said to be hindered by the comparatively rapid drying of their surfaces. More usually in the high temperatures the animals _take to the water_ and copulate there. The eggs are ejected into the water, and as their gelatinous coverings immediately swell up, they do not stick to the males. The offspring thus derived from the parents subjected to heat for one breeding-period only, whether they were laid in water or on land, did not show departures from the normal type. Kammerer states next, however, that in subsequent breeding-periods the same parents frequently take to the water to breed, though they have become quite accustomed to the heated chamber; and furthermore that if such animals, having thus lost their instinct to brood their young, be transferred to ordinary temperatures they do not readily reassume their normal habits, but for several breeding seasons--at least four--will take to the water. These parents lay from 90 to 115 eggs, which are small and contain little yolk, and the larvae, on hatching, breathe with their embryonic gills until they are absorbed instead of being broken off as normally. The offspring thus abnormally developed when they mature are said never to brood their eggs. If they are derived from the earlier spawnings of their parents, before, that is to say, the parents had been submitted to the changed conditions long enough to transmit their effects, they lay on land; but if they are derived from the later spawnings, they lay in the water. These changes of habit are manifested without the continued application of the abnormal experimental conditions, and, as I understand the account, in normal conditions of temperature. If the abnormal experimental conditions are continued, the toads always lay in water, and their eggs become progressively smaller and more numerous. The larvae in the fourth generation acquire three pairs of gills instead of one pair, and are in other respects also different from the normal form. Respecting the _Alytes_ bred in this way Kammerer makes the very striking statement that _the males in the third generation_ (p. 535) _have roughened swellings on their thumbs and that in the fourth generation_ (pp. 516 and 535) _these swellings develop black pigment_. Together with the appearance of this secondary sexual character there is hypertrophy of the muscles of the fore-arm. To my mind this is the critical observation. If it can be substantiated it would go far towards proving Kammerer's case. _Alytes_, among toads and frogs, is peculiar in that the males do not develop these lumps in the breeding season, and the fact may no doubt be taken to be correlated with the breeding habits, copulation occurring on land and not in water as is usual with Batrachians. It is to be expressly noticed that these lumps on the thumbs or arms of male toads and frogs are not merely pigmented swellings, but are pads bearing numerous minute horny black spines, which are used in holding the females in the water. The figures which Kammerer gives (Taf. XVI, figs. 26 and 26a) are quite inadequate, and as they merely indicate a dark patch on the thumbs it is not possible to form any opinion as to the nature of the structure they represent. The systematists who have made a special study of Batrachia appear to be agreed that _Alytes_ in nature does not have these structures; and when individuals possessing them can be produced for inspection it will, I think be time to examine the evidence for the inheritance of acquired characters more seriously. I wrote to Dr. Kammerer in July, 1910, asking him for the loan of such a specimen[13] and on visiting the Biologische Versuchsanstalt in September of the same year I made the same request, but hitherto none has been produced. In matters of this kind much generally depends on interpretations made at the time of observation; here, however, is an example which could readily be attested by preserved material. I notice with some surprise that in a later publication on the same subject no reference to the development of these structures is made (see below). The statements here given represent but a small part of Kammerer's papers on the subject. He gives much further information as to the course of the experiments, especially in regard to the fate of the eggs laid on land and the aberrations induced in them by treatment. The ramifications of the experiments are, however, very difficult to follow, and as I am not sure that I have always understood them I must refer the reader to the original. More recently Kammerer has published[14] a most curious account of experiments in crossing his modified and abnormal _Alytes_, derived from the water-eggs, with normal individuals. In the first case the cross was made between a _normal female_ and an _abnormal male_. The offspring were normal in their habits. In the next generation bred from these almost exactly a quarter showed the abnormal instinct. The reciprocal cross was made between an _abnormal female_ and a _normal male_. In this case the offspring were abnormal in their behaviour; but the second generation bred from them showed three quarters abnormal and one quarter normal. Certain details as to numbers and sexes of the various families bred in the course of this amazing experiment are given in a subsequent publication.[15] This later paper goes somewhat fully into the question of the difference in behaviour between the normal and modified individuals, describing the ways in which the males and females possessing the acquired character could be recognised from the males and females which were normal, but in this account I find no reference to the development of the "_Brunftschwielen_"--the horny pads on the hands of the males. As these structures would be of special value in such a diagnosis the omission of any allusion to them calls for explanation. Kammerer claims the evidence as proof of Mendelian segregation in regard to an acquired character, the first example recorded. Pending a repetition of the experiments there is no more to be said. 2. _The Mode of Reproduction of Salamandra atra and maculosa._[16]--_Salamandra maculosa_, the common lowland form, with yellow bands or spots, deposits its young in water, generally as gill-bearing tadpoles, with a wide, swimming tail, though occasionally they are born still enclosed in the egg-capsule out of which they soon hatch. Spawning extends over a considerable period, often many weeks, and during the season one female may bear more than 50 young. _S. atra_, the black Alpine form, produces its young on land. They are born without gills, ready to breathe air, and with the rounded tail of the adult. These differences may, as Kammerer says, naturally be regarded as adaptations to the Alpine conditions. Moreover, the female bears _only two_ young in a season, and this reduction in the number must be taken to be a consequence or condition of viviparity. There are many eggs in the ovary, but all except the two which are destined to develop degenerate and form a yolk-material on which these two survivors feed. Kammerer gives a long account of the various conditions to which he subjected both species. The treatment was complicated in many ways, but the essential statements are, as regards _S. maculosa_, that when no water was provided in which the young might be born, they were dropped on land, larger and in a later stage of development and of a darker colour than is normal; that the larvae so born gradually diminished in number until only two were deposited in each breeding-period; that dissection showed that the other ova degenerated to form a yolk-material. The larvae so produced reached maturity. The summary of results describes their behaviour, stating that they produced: (_a_) _In water_, either (1) _very_ advanced, large-headed larvae 45 mm. long (instead of 25-30 mm.) with gills already reduced, which had awkward, embryo-like movements, and in some few days metamorphosed into small perfect salamanders; or (2) moderately advanced, properly proportioned larvae, 40-41 mm. long, provided with large gills of (at first) intrauterine character, which were reduced during aquatic life. (_b_) _On land_, small (26 mm. long) larvae with rudimentary gills, having the body rounded instead of being flattened from above downwards, and an elongated narrow head, which were unable to live in deep water. These larvae changed to the salamander colour in 10-12 days, and after four weeks metamorphosed into salamanders 29 mm. long. (_c_) In the foregoing cases the experimental conditions were not continued, or in other words, basins of water were provided in which they could spawn. But if the experimental conditions are continued, these _Salamandra maculosa_ which were born newt-like (viz., not in a larval condition), are themselves newt-bearing from the first time they give birth, using the dry land, and bringing forth only two young, the normal number for the births of _S. atra_. These young are 40-41 mm. long, and are dark-coloured, resembling greatly the normal new-born _S. atra_. This epitome of the observations illustrating the inheritance of acquired characters has been very widely quoted, and may not unnaturally be taken to summarize a wide experience of the modified animals. Reference to the details given in the same paper shows that, as alleged, each of the four types of behaviour enumerated was witnessed _once_ only in the case of each of four females, no two agreeing with each other. As to the number of the males or their habits nothing is said. The first female, _a_ (1), bore five young; the second, _a_ (2), bore two, of which one was a partial albino; the third, _b_, produced four young; and the fourth, _c_, two as already stated. In the case of _c_ the details show that the female gave birth immediately after being transferred from the open-air terrarium to one indoors, which contained no basin of water. This is the example of the consequences which follow on a continuance of the experimental conditions.[17] As regards _S. atra_ the converse is reported. Various means were used to induce them to eject their young prematurely in water, such as massaging the sides of the mothers, or raising the temperature to 25° or 30° C., with various degrees of success. But afterwards it was found that specimens collected wild at an elevation of about 1,000 metres responded to much simpler treatment, and gave birth prematurely in water when they were kept in a large shallow basin of water not so deep but that they could everywhere touch the bottom with their feet and keep their heads above the surface. With specimens collected at higher elevations this treatment was inoperative, and the suggestion is made that _S. atra_ at the lower confines of its habitat partakes more of the nature of _maculosa_ than do the individuals from greater heights; for Kammerer argues that pools suitable for breeding must be more uncommon at those elevations than they are lower down. In the earlier paper[18] Kammerer states that newly caught females of _S. atra_ often give birth in the water, and show an undoubted preference for doing so. He describes also how he once saw several females, wild in their natural habitat, lay their young in a rain-puddle at 1,800 metres elevation, but the larvae thus born were fully formed. When the deposition of the young as larvae has become "habitual"[19] with _S. atra_, three to nine larvae may be produced at one spawning period, from 35 to 45 mm. long, with gills at most 8 mm. long, and a tail-fin 2-3 mm. broad. Such larvae are generally coffee-brown, or grey (instead of black), and show other minor differences. The summary states that when grown to maturity they become in their turn larva-bearing, and go into the water to bring forth. Their young are more than two (3 to 5 being the numbers observed) with a length of 33-40 mm. or of 21-23 mm. at birth. They are light grey, spotted (mottled with lighter and darker colour), have relatively short gills (8 to 9 mm. at most) and a broad tail-fin (3 mm. wide). At metamorphosis they are relatively long (44 mm.) and one of them had some yellow pigment. Here again this summary is, as a matter of fact, describing the behaviour of two mothers, of which one produced three, and the other five young. To my mind these experiments suggest that the reproductive habits of both species, if closely observed, will be found to be subject to considerable variation, and I think it not impossible that each species is, especially in confinement, capable of being a good deal deflected from its normal behaviour. Moreover, there seems to me no great improbability in the idea that there is an interdependence between the number of young and the stage of maturity in which they are born. But, at the same time, the case as told by Kammerer strikes me as proving too much. If each species is so sensitive to conditions that the normal procedure is gravely modified in one generation, and if that modification can reappear in a pronounced form in the next generation without a renewal of the disturbing conditions, it becomes extremely difficult to understand how the regularity which each species is believed to display in nature can be maintained. Surely both species might be expected to be in confusion. From a passage in Kammerer's earlier paper (1904, p. 55) on the subject, I infer that he also would expect considerable irregularity in the natural behaviour, but that he has not investigated the point.[20] 3. _Modification of the Colour of Salamandra maculosa induced by Change in the Colour of the Soil on which the Animals were kept._--Kammerer speaks of this as the most convincing of all his experiments on the transmission of acquired characters. So far, however, no full account of them has been published.[21] The statement is that when salamanders are kept in yellow surroundings the yellow markings gradually in the course of years increase in amount relatively to the black ground colour. Conversely by keeping the animals on black garden soil, the yellow may be greatly diminished in quantity until it largely disappears. (The account in _Natur_ adds that very moist conditions also favour the increase of yellow, and that with less moist conditions the yellow diminishes.) From each kind, the (induced) yellower and the (induced) blacker, a second generation was raised, on soil of neutral colour, and each family was later divided into two parts, half being put on black and half on yellow ground. As regards the offspring of those which had lived on _black_ soil no positive result had been reached up to the date of publication, but it is stated that these young resembled their parents in having the yellow distributed in _irregular spots_. As regards the offspring of those which had lived on yellow soil the account follows up the story of that part of the offspring which were put on yellow soil again. It is stated that these, though derived from parents with irregular spots, _developed the yellow as longitudinal bands_. This account is given with slight differences of expression in the three places to which I have referred. On returning from Vienna in 1910 I consulted Mr. G. A. Boulenger in reference to the subject, and he very kindly showed me the fine series from many localities in the British Museum, and pointed out that in nature the colour-varieties can be grouped into two distinct types, one in which the yellow of the body is irregularly distributed in spots and one in which this yellow is arranged for the most part in two longitudinal bands which may be continuous or interrupted. _The spotted form is, as he showed me, an eastern variety, and the striped form belongs to western Europe._ Mr. E. G. Boulenger[22] has since published a careful account of the distribution of the two forms. The spotted he regards as the typical form, var. _typica_, and for the striped he uses the name var. _taeniata_. The typical form occupies eastern Europe in general, including Austria and Italy, extending as far west as parts of eastern France. The var. _taeniata_ is found all over France, excepting parts of the eastern border, Belgium and western Germany, Spain and Portugal. Of the very large series examined there was only one specimen (Lausanne) which could not with confidence be referred to one or other of the two varieties. Mr. E. G. Boulenger points out that both varieties inhabit very large areas, and live on soils of most different colours and compositions. Both are liable to variations in the amount and the shade of the yellow, but that any suggestion that _taeniata_ belongs especially to yellow soils and _typica_ to black soils is altogether inadmissible. He expresses surprise that Kammerer should not allude to these peculiarities in the geographical distribution of the two forms. He suggests further that it is more likely that some mistake occurred in Kammerer's observations than that the east European _typica_ should, in the course of a generation, have been transformed into the west European _taeniata_ by the influence of yellow clay soil. In his last paper on the subject Kammerer states incidentally[23] that he has found the _striped form recessive to the spotted_. No evidence for this statement is given, and I have not found any other reference to crosses effected between the two natural types. If, however, this representation is correct, it is conceivable that the production of _taeniata_ from _typica_ was in fact the re-appearance of a recessive form. The plate which Kammerer gives in illustration of his modified parent figures a single animal at four stages, and though it is certainly more like the spotted than the striped form, it has a certain suggestion of the striped arrangement, such as I can well imagine being produced in the heterozygote.[24] In continuation[25] of the experiments on the colour of _S. maculosa_ Kammerer publishes an account of elaborate experiments in grafting ovaries of the various forms, modified and unmodified, into each other, and describes the offspring which followed. Before pursuing this part of the inquiry I am disposed to wait until the earlier steps have been made much more secure than they yet are. More recently Kammerer has published similar statements in regard to the inheritance of characters induced in various lizards by keeping them in abnormal temperatures, high and low. The changes induced affected in some species the colours, in others the reproductive habits. Respecting these examples I feel the same scepticism that I have indicated in regard to the others, somewhat heightened by the fact that insufficient evidence is given both regarding the behaviour of these various species in captivity when not subjected to abnormal temperatures, and in the wild state. Respecting this part of the evidence Mr. G. A. Boulenger has lately published a criticism[26] from which I extract the following passages. Referring to a previous note[27] on the question of the melanism of the various insular forms of _Lacerta muralis_ he writes: "I also alluded (_l. c._) to the theories that have been propounded to explain the melanism of various insular forms. This is a subject which has been lately taken up by Dr. Kammerer at the Biologische Versuchsanstalt in Vienna, and he claims to have produced nigrinos artificially by a very strong elevation of the temperature, accompanied by extreme dryness. Dr. Werner[28] has already opposed his own experiments to those of Kammerer, artificial melanism having been produced by him in _Lacerta oxycephala_ by keeping two very light specimens from Ragusa for a whole summer in very damp conditions. Neither is Kammerer's theory in accordance with the distribution of the black lizards, as pointed out by Werner. Kammerer also finds that those forms which are known to produce melanic races in a state of nature, lend themselves more readily than the others to the success of his experiments. But he shows himself misinformed when he states that the variety called _Lacerta fiumana_ belongs to the category of those of which black forms are not known. He overlooks the fact, first pointed out by Scherer in 1904, and which I can confirm, that the black lizard from Melisello near Lissa in the Adriatic is unquestionably derived from the lizard from Lissa, which he correctly regards as not separable from _L. fiumana_...." "Another colour modification which Dr. Kammerer states that he obtained by raising the temperature is the assumption by the female of the typical _Lacerta muralis_ of the bright red colour of the lower parts which often distinguishes the male from the female, and which was not shown by the individuals of the latter sex kept by him under normal conditions. He quotes various authorities to show that the lower parts are never red in the females, but he has omitted to consult others who say the contrary. Thus Bedriaga (1878 and 1879) remarks that a so-called var. _rubriventris_ of the typical wall lizard has the lower parts red in both sexes."[29] In reading such papers as those of Semon or Kammerer the thought uppermost in my mind is that to multiply illustrations of supposed transmission of acquired characters is of little use until some one example has been thoroughly investigated. If we had certain assurance that even a single unimpeachable case could be repeated at will, the whole matter would assume a more serious aspect. If, for instance, Kammerer were able to show us _Alytes_ males with horny pads on their hands, it would be something tangible; still more, if the experiment were repeated by others until no doubt remained that the offspring of _Alytes_ which had bred in water for some three generations did acquire these pads and that they could transmit these novelties to descendants raised in normal conditions. Till evidence of this kind is published by at least two independent observers investigating similar material, I find it easier to believe that mistakes of observation or of interpretation have been made than that any genuine transmission of acquired characters has been witnessed. Meanwhile there is no denying that the origin of adaptational features is a very grave difficulty. With the lapse of time since evolutionary conceptions have become a universal subject of study that difficulty has, so far as I see, been in nowise diminished. But I find nothing in the evidence recently put forward which justifies departure from the agnostic position which most of us have felt obliged to assume.[30] APPENDIX TO CHAPTER IX. Professor G. Klebs, as is well known to students of evolutionary phenomena, has for several years been engaged in investigations relating to the inheritance of acquired characters. In his many publications on the subject the issue has always been represented as more or less uncertain. Desiring to know how the matter now stands according to Professor Klebs' present judgment I wrote to him asking him to favour me with a brief general statement. This he most kindly sent in a letter dated 8th July, 1912. As such a statement will be read with the greatest interest by all who are watching the progress of these studies I obtained permission to publish it as follows: 8. Juli 1912 Ihre liebenswurdige Anfrage will ich sehr gern beantworten, obwohl ich sie nicht so beantworten kann wie ich erwünschte. Ihr Skepticismus in der Frage der Uebertragung erworbener Charactere auf die Nachkommen ist nur zu berechtigt. Meine Versuche mit Veronica sind _nicht_ beweisend, da es mir bisher nicht gelungen ist eine einigermasse konstante Varietät mit verlaubten Inflorescenze zu erzeugen. In Bezug auf mein Semper vivum bin ich allerdings noch heute der Meinung dass die starke künstliche Veränderung der Blüte einen Einfluss auf einzelnen Nachkommen gehabt hat. Ich habe seither nichts darüber veröffentlicht: die Mehrzahl der anormalen gefüllten Blüten war leider steril. Von einem weniger veränderten Exemplar erhielt ich einige Sämlinge, aber sie haben noch nicht geblüht. Es kann sich in diesem Falle nur um eine _Nachwirkung in der ersten Generation_ handeln, vergleichbar jenen Fällen in denen Samen von Bäumen aus den hohen Alpen in der Ebene gewisse Nachwirkungen zeigen. Aber es ist bisher kein sicherer. Fall bekannt in den der kunstliche herbeigeführte Charakter _mehrere Generationen hindurch unter der gewöhnlichen "normalen" Bedingungen_ übertragen worden ist. Auf der andere Seite sind diese negativen Resultaten nicht entscheidend. Denn wie wenig ist in dieser Beziehung überhaupt ernstlich versucht worden! Und zweifellos geht die Sache nicht so einfach. Ich versuche es mit anderen Pflanzen weil ich der Meinung bin dass es möglich sein müsse wenigstens solche neuen Varietäten zu erzeugen, wie sie die Gartenvarietäten entsprechen. Aber bis jetzt leider sind die Versuche nicht gelungen, weder mir noch irgend einem anderen. FOOTNOTES: [1] Semon, R., Der Stand der Frage nach der Vererbung erworbener Eigenschaften, published in _Fortschr. der naturw. Forschung._, Bd. 11, 1910. [2] Standfuss, M., _Denks. Schweiz. naturf. Ges._, XXXVI, 1898, p. 32. [3] Fischer, E., _Allg. Ztschr. f. Entomologie_, Bd. VI, 1901. [4] Out of 12 pupae treated 8 died and of the 4 survivors, one only was affected. See M. v. Linden, _Archiv. Rassen. u. Gesells._, 1904, I. [5] For illustrations see _Oberthur's �tudes d'Entom._, 1896, where many of these curious aberrations are represented; also Barrett, _Lepid. Brit. Islands_, II, pp. 71 and 72. [6] Schübeler, F. C., _Die Culturpflanzen Norwegens_, 1862, especially pp. 24 and 28. [7] I am obliged to him and to Dr. E. Gold for much trouble taken to answer my questions. Some idea of the kind of weather indicated by an average of 2.76° C. above the mean may be got from a comparison with the year 1911, which most people will remember as one of the hottest summers they have known. The July of that year was in east and southeast England about 4° F. above the mean but 2.67 C. means about 4.8° F. above the mean. At Greenwich July, 1859, was about 6.5° F. above the average. [8] Wille, N., _Biol. Cbltt._, XXV, 1905, p. 521. [9] Wettstein, R. von. _Der Neo-marckismus u. seine Beziehungen zum Darwinismus_, Jena, 1903. [10] T. Graham Brown, _Proc. Roy. Soc._, 1912, vol. 84, B, p. 555. This paper gives full reference to the previous literature of the subject. [11] Morgan, T. H., _Evolution and Adaptation_, New York, 1903. [12] Kammerer's chief paper on this subject is in _Arch. f. Entwm._, 1909, XXVIII, p. 447, and it is to this that the paginal references in the present text relate. His previous paper appeared, _ibid._, 1906, XXII, p. 48. An account of his further experiments with _Alytes_ is given in _Natur_, 1909-10, Heft 6, p. 95. [13] In reply to my letter Dr. Kammerer who was then away from home very kindly replied that he was not quite sure whether he had killed specimens of _Alytes_ with "_Brunftschwielen_" or whether he only had living males of the fourth generation, but that he would send illustrative material. [14] Kammerer, P., _ Natur_, 12 December, 1909, Heft 6, p. 95, repeated in _12 Flugschrift d. Deutsch Ges. f. Züchtungskunde_, Berlin, 1910. [15] _Festschrift zum Andenken an Gregor Mendel_, being vol. XLIX of the _Verh. Naturf. Ver. in Brünn_, 1911, p. 98. [16] Kammerer's chief papers on this subject are _Archiv fur Entwm._, XVII, 1904, and _ibid._, XXV, 1907. An epitome of results is also given by him in _12 Flugschrift d. Deutsch. Ges. f. Züchtungskunde_, Berlin, 1910. [17] "_Bei Fortdauer der Versuchsbedingungen sind als Vollmolche geborene Salamandra maculosa_ gleich bei der ersten Geburt _abermals voll molchgebärend_, benutzen zum Geburtsakt das trockene Land, und zwar unter Erreichung der (bei _Salamandra atra_ normalen) _Embryonen-Zweizahl_," Kammerer, 1907, p. 49. [18] 1904, p. 56. [19] Throughout Kammerer's papers this is used almost as a technical term. It means, I presume, that the feature was manifested more than once. [20] It should be stated that the papers contain a quantity of detail, especially descriptive of the state of the larvae, which I have not attempted to represent, but the account here given contains all that seemed essential to an understanding of the more important features of the account. [21] The first appeared in _Natur_, 1909-10, Heft 6, p. 94; and the second, which contains coloured plates of the animals, in the lecture already referred to, _12 Flugschr. d. Deut. Ges. f. Züchtungkunde_, Berlin, 1910, p. 26. In the paper in _Mendel Festschrift_, 1911, the subject is continued, but no more is added as to this part of the experiment. [22] E. G. Boulenger, _Proc. Zool. Soc._, 1911, p. 323. [23] _Mendel Festschrift_, 1911, p. 84. [24] _12 Flugschrift. Deut. Ges. Züchtungskunde_, 1910, Fig. 15, _P. Reihe_. [25] _Mendel Festschrift_, 1911, p. 83. [26] Field, 1912, 30 March. [27] _Ibid._, 1904, p. 863. [28] _Mitth. Naturw. Ver. a. d. Univ. Wien_, 1908, p. 53. [29] As to the variations of _Lacerta muralis_ in Western Europe and North Africa see Boulenger, G. A., _Trans. Zool. Soc._, 1905, vol. XVII, p. 351. [30] As to the experiments of Klebs relating to the transmission of acquired characters, see Appendix. CHAPTER X EFFECTS OF CHANGED CONDITIONS CONTINUED THE CAUSES OF GENETIC VARIATION In the last chapter we examined some of the evidence offered in support of the belief that adaptation in highly organised forms is a consequence of the inheritance of adaptative changes induced by the influence of external conditions. The state of knowledge of this whole subject is, as I have said, most unsatisfactory, chiefly for the reason that in none of the cases which are alleged to show a positive result have two observers been over the same ground, or as yet confirmed each other. In the wider consideration respecting the causes of variation at large we find ourselves still in the same difficulty. The study has thus far proved sadly unfruitful. In spite of the considerable efforts lately made by many observers to induce genetic variation in highly organised plants or animals, and though successes have occasionally been announced, I do not know a single case which has been established and confirmed in such a way that we could with confidence expect to witness the alleged phenomena if we were to repeat the experiment. Abundant illustrations are available in which individuals exposed to novel conditions manifest considerable changes in characters or properties, but as yet there is no certain means of determining that germ-cells of a new type shall be formed. Of the direct effect of conditions the lower organisms, especially bacteria, offer the best examples, the alterations of virulence which can be produced in so many distinct ways being the most striking and familiar. That attenuation of virulence can be produced by high temperatures or by exposure to chemical agents, and that this diminution in virulence may remain permanent is, from our point of view, not surprising; but the fact that in many cases the full virulence can by suitable cultivation be restored is difficult to understand. Similar variations have been observed in power of pigment production and other properties. These phenomena naturally raise the question whether any cases of apparent loss of factors in higher forms may be comparable. The subject of variations in the lower organisms and their dependence on conditions is a highly special one, and I have no knowledge which can justify me in offering any discussion of them, but I understand that hitherto little beyond empirical recognition of the phenomena has been attempted. A useful summary of observations made by many investigators was lately published by Hans Pringsheim,[1] who enumerates the different agencies which have been observed to produce modifications, and the various ways in which these changes are manifested. One of the most comprehensive studies of the subject from the genetic point of view is that made by F. Wolf.[2] In his extensive cultivations of _Bacillus prodigiosus_, _Staphylococcus pyogenes_ and _Myxococcus_ he succeeded in producing many strains with modified properties. In most of these the modifications arose in consequence of the application of high or low temperatures or of the addition of various chemical substances to the culture-media. Some of the variations, which are for the most part in the powers of pigment-formation, persisted when the strains were returned to normal conditions, and others did not. In reference especially to the variations witnessed in the Cocci the reader should consult the critical account of variation in that group published by the Winslows,[3] where much information on the subject is to be found. The authors attempted to determine the systematic relationships of the several forms, as far as possible, by the application of statistical methods. The result is interesting as showing that the problem of species in its main features is presented by these organisms in a form identical with that which we know so well in the higher animals and plants, whatever properties be selected as the diagnostic characters. There are many types perfectly distinct and others which intergrade. Some of the types change greatly with conditions while others do not. This is exactly what we encounter whenever we study the problem of species on an extended scale among the higher forms of life. There is now practically complete agreement among bacteriologists that the observations made first by Massini on the change in color of _Bacterium coli mutabile_ grown in Endo's medium, associated with the acquisition of the power to ferment lactose, are perfectly reliable and free from possibilities of mistake. The work has been extended and confirmed by many workers, especially R. Müller, who finds that this bacterium can similarly acquire and maintain the power to ferment other sugars. A careful account of the whole subject written by Müller for the information of biologists will be found in _Zts. für Abstammungsl._, VIII, 1912. After discussing the biological significance of the facts, he concludes with a caution to the effect that bacteria are so different from all other living things that generalizations from their behavior must not be indiscriminately applied to animals and plants. In all work with this class of material there is obviously danger of error through foreign infection of the cultures, but there can be no doubt that though some of the "mutations" recorded may be due to this cause, the majority of the instances observed under stringent conditions are genuine. Another and equally serious difficulty besetting work with bacteria and fungi cultivated from spores is that the appearance of variation may in reality be due to the selection of a special strain previously living masked among other strains. This possibility must be remembered especially in those instances which are claimed as exemplifying the effects of acclimatisation. Manifestly this consideration can be urged with most force when the strain which gave rise to the novelty was not raised from a single individual spore. Moreover, when once the possibility of spontaneous variation is admitted, it must be difficult to be quite confident that any given variation observed is in reality due to the novel conditions applied, and as I understand the evidence, the appearance of the mutational forms does not with any regularity follow upon the application of the changed conditions. Researches into the variation of these lower forms will, no doubt, be continued on a comprehensive scale. So long as the instances recorded are each isolated examples it is impossible to know what value they possess. If they could be coordinated in such a way as to provide some general conception of the types of variation in properties to which bacteria, or any considerable group of them, are habitually liable, the knowledge might greatly advance the elucidation of genetic problems. Of mutational changes directly produced with regularity in micro-organisms by treatment, the experiments with trypanosomes provide some of the clearest examples. A summary of the evidence was lately published by Dobell,[4] from which the present account is taken. The most definite fact of this kind established is that certain dyes introduced into the blood of the host have the effect of destroying the small organ known as the "kinetonucleus" in the trypanosomes. The trypanosomes thus altered continue to breed, and give rise to races destitute of kinetonuclei. This observation was originally made by Werbitzki and has been confirmed by several observers. The exact way in which this alteration is effected in the trypanosomes is not quite definitely made out, but there is good reason for supposing that the dyes have a direct and specific action upon the kinetonucleus itself, and circumstances make it improbable that in some division a daughter-organism without that body is produced, or that any selection of a pre-existing defective variety occurs. Ehrlich has suggested with great probability that the dyes which possess this action owe it to the fact that they have the particular chemical linkage which he calls "ortho-quinoid." In outward respects, such as motility and general appearance, the modified organisms are unchanged, but their virulence is diminished. As regards the possibility of the defective strain reacquiring the kinetonucleus, Werbitzki states that in one case passage through 50 animals and treatment with dyes left the strain unaltered; but that in another case at the sixteenth passage 7 per cent. of the trypanosomes were found to have re-acquired the organ, and in subsequent passages the percentage increased, until at the twenty-seventh passage practically all had re-acquired it. Kudicke, however, in similar experiments did not succeed in causing re-acquisition by transplantation. By the action of various drugs and anti-bodies races of trypanosomes resistant to those substances have been obtained. These breed true, at least when kept in the same species of animal in which the resistance was acquired. As to whether change of virulence is produced by passage through certain animals or not, there is as yet no general agreement. Other changes, especially in size and some points of structure, are said to occur when certain trypanosomes proper to mammals are passed through cold-blooded vertebrates (Wendelstadt and Fellmer), and it is stated that these changes persist, but the observations have not yet been confirmed. Experiments lately conducted by Woltereck with _Daphnia_ are interesting as having given a definite positive result, in so far, at least, as the ova were affected by conditions before leaving the bodies of the parent individuals. The observations relate to the offspring resulting from _parthenogenetic_ eggs. Females bearing ephippia (fertilised eggs) were isolated until the ephippia were dropped, and in this way the offspring of fertilisation were excluded. Males, of course, appeared from time to time in the cultures, but as fertilised eggs were rejected, their presence did not disturb the result. The most remarkable observations related to _Daphnia longispina_. This species as found in the lower lake at Lunz had the front end of the body blunt and nearly round in profile; but on being cultivated in a warm temperature and with abundant nourishment the front end of the body became produced into an elongated "helmet," as Woltereck calls it. Experiment showed that the change was primarily due to the abundance of food, and owing to temperature in a subordinate degree. This distinction arose as soon as the species was taken into the hothouse, but when the modified individuals were put back into the original conditions, a lower temperature and scanty food-supply, the next generation returned to their original form. After being cultivated for two years and about 40 generations in the more favourable conditions, when similarly put back into the lower temperature with scanty food the _first generation_ born in these conditions was helmeted like the modified parents. Woltereck is of opinion that the ova were still unformed at the time the parents were put back, and the influence of the favourable conditions upon the unformed ova he speaks of as a "prae-induction." The effect never extended beyond the one generation, after which the strain returned to its original state. The fact that the influence on the offspring was not manifested at first led Woltereck to expect that by more prolonged cultivation in the favourable conditions a further extension of this influence would be produced, but this expectation was never fulfilled, though the attempt was made again and again. Similar experiments were made with _Hyalodaphnia cucullata_, which is far more sensitive to cultural influences, and in nature manifests a considerable elongation of the helmet as a seasonal modification, but the results were essentially the same as in the preceding case, no modification extending beyond the first generation born after the restoration to _normal conditions_.[5] The only criticism of these extremely interesting results which suggests itself is that perhaps the original appearance of the modification was not in reality due to an _accumulated_ effect of the conditions, but to some change in the conditions themselves which was not noticed. It is difficult to see how length of time or even the lapse of several generations could have so specific an effect on the race. It is no doubt often vaguely supposed by many that a long period of time may be necessary for the effect of climate or of other environmental conditions to be produced in an organism which does not thus respond at first. I have never been able to see any reason for this opinion nor how it is to be translated into terms of physiological fact, and I imagine that in those cases in which the lapse of time is really required for the production of an effect, the influence of the prolongation is rather on the conditions than on the organisms. The response of the organisms thus probably indicates not that the creature is at length feeling the effects because of their accumulated action on itself, but that the conditions have at length ripened. As this sheet is passing through the press Agar has published[6] an abstract of evidence as to another comparable case in a parthenogenetic strain in the daphnid, _Simocephalus vetulus_. When fed on certain abnormal foods the shape of the body is changed, the edges of the carapace being rolled backwards so as to expose the appendages. The offspring of animals thus modified showed similar modification in the first, and to a very slight degree, in the second generation, though the original mothers were removed to normal conditions before their eggs were laid. In the third generation there was "a very pronounced reaction in the opposite direction." Agar suggests that the change may be due to some toxin-like substances, carried on passively by the egg into the next generation, against which the protoplasm eventually produces an anti-body. The experiments which have been in recent years regarded by evolutionary writers as the most conclusive proof that direct environmental action may produce germinal variation are those of Professor W. L. Tower, of Chicago, on _Leptinotarsa_, the potato beetles. This work has attained considerable celebrity and has been generally accepted as making a definite extension of knowledge. After frequently reading Tower's papers and after having been privileged to see some of the experiments in progress (in 1907) I am still in doubt as to the weight which should be assigned to this contribution. The work is described in two chief publications, the first of which appeared in 1906.[7] This treatise contains a vast amount of information about numerous species and varieties of these beetles which the author has observed and bred in many parts of their distribution throughout the United States, Mexico and Central America. The part of the book which has naturally excited the greatest interest is that in which Tower states that by subjecting the beetles to change in temperature and moisture, he caused them to produce offspring quite unlike themselves, which in several cases bred true. It is much to be regretted that the author did not happen to become acquainted with Mendelian analysis at an earlier stage in the investigation. The evidence might then have been handled in a much more orderly and comprehensive way, and a watch would have been kept for several possibilities of error. The headquarters of the genus is evidently as Tower states, in Mexico and the adjoining countries. In this region there is a great profusion of forms, some very local, some as for instance the well-known _decemlineata_,[8] more widely spread. The distinctions are almost all found in peculiarities of colour and pattern, and the limits of species are even more indefinable than is usual in multiform animals. Tower arranges the various types into seven groups of which the one most studied is that which he calls the _lineata_ group. To this group belong all the forms to which reference is here made, and, as I understand, they differ among themselves entirely in size, colour and pattern. There is no suggestion of infertility in the crosses made between the several forms of the _lineata_ group; in fact they present, like many Chrysomelidae, a good example of what most of us would now call a polymorphic species, consisting of many types, some found existing in the same locality, others being geographically isolated. A series of experiments was devoted to the attempt to fix strains corresponding to the extremes of continuous variations. For example, those with most black pigment and those with least black taken from a population continuously varying in this respect, were separately bred; but almost always the selection led to no sensible change in the position of the mean of the population. The variations in these cases were evidently fluctuational. In some instances, however, real genetic differences were met with, and strains exhibiting them were, as usual, rapidly fixed. Tower points out that several of the varieties (or species, as he prefers to call them) were obviously recessive to _decemlineata_. This is most clearly demonstrated in the case of the form called _pallida_, which is a pale depauperated-looking creature, with the orange of the thorax almost white and the eyes devoid of pigment.[9] This form behaved as an ordinary Mendelian recessive, breeding true whenever it appeared in the cultures, or when individuals found wild were studied in captivity. A black form which Tower names _melanicum_ was similarly shown to be a Mendelian recessive. Wild specimens of this variety of opposite sexes were not found simultaneously in nature, and there was thus no opportunity of breeding them together, but the hereditary behaviour was seen in the F_{2} generation from a _melanicum_ found coupled with _decemlineata_. Experiments also occurred giving indication that a variety with the stripes anastomosing in pairs (_tortuosa_), was another recessive, and that a variety--called "_rubri-vittata_"--gave an intermediate F_{1} with subsequent segregation. All these are forms of _decemlineata_ Stål. Similar observations were made regarding forms recessive to _multitaeniata_ Stål. Of these two were thrown by _multitaeniata_ itself, namely a form named by Stål _melanothorax_, and regarded by him as a species, and one which Tower names _rubicunda_ n. sp. The facts proving the recessive behaviour of their several forms will be found in the following places in Tower's book: _pallida_, pp. 273-278. _melanicum_, p. 279. _tortuosa_, p. 280. _rubrivittata_, pp. 280-281. _melanothorax_ and _rubicunda_, pp. 283-285. Following this evidence of recessive nature of the six forms enumerated, Tower describes experiments showing, as he believes, that some of them may be caused to appear by applying special treatment to the parents during the "growth and fertilisation" (p. 287) of the eggs. The most striking example is that in which 4 males and 4 females of _decemlineata_ were kept very hot (average 35° C.) and dry, and at low atmospheric pressure (19-21 inches). The eggs laid were restored to natural conditions. These gave 506 larvae, from which emerged 14 normal, 82 _pallida_ and 2 "_immaculothorax_," viz., without pigment on the pronotum. The account of the rest of the experiment is somewhat involved, but I understand that the _pallida_, of which two only survived, behaved as normal recessives when bred to the type: also that the parents, after having laid the eggs whose history has been given, were restored to normal conditions and laid 319 eggs which gave 61 normals. In another case normal parents laid 409 eggs in the hot and dry conditions, and on restoration to normal conditions, the same parents laid 840 eggs. Then 409 eggs gave 64 adults as follows: _Males_ _Females_ _decemlineata_ 12 8 _pallida_ 10 13 _immaculothorax_ 2 3 _albida_ 9 7 --- --- 33 31 The 840 eggs laid in normal conditions gave 123 normal _decemlineata_. Similar experiments were made with _multitaeniata_ and gave comparable results, the two recessives (_melanothorax_, _rubicunda_) being produced in large numbers when the parents were subjected to heat, but in this case the atmosphere was kept _saturated_ with moisture, instead of dry, as in the previous instance. The same parents transferred to normal conditions gave normals only. Lastly the form _undecimlineata_ was exposed "to an extreme stimulus of high temperature, 10° C. above the average," and a dry atmosphere, with the result that from 190 eggs there emerged 11 beetles, all of the form _angustovittata_ Jacoby, which subsequently bred true to that type (see p. 295). In the results of these experiments, as described, there is one feature which I regard as quite unaccountable. Tower makes no comment upon it. Indeed, from the general tenour of the paper, I infer, not only that he does not perceive that he is recounting anything contrary to usual experience, but rather that he regards the result as conforming to expectations previously formed. The point in question is the genetic behaviour of the dominant normals produced under the abnormal conditions. These normals were the result of the breeding of parents declared to be at the same time giving off many recessive gametes. Some of these normals must be expected therefore to be heterozygous unless some selective fertilisation occurs. Nevertheless in every case they and their offspring are reported to have continually bred true. I allude especially to the tables given on pp. 288, 289, 292, and 293. Tower does not mention any misgiving about this result, and I think he regards himself as recounting phenomena in general harmony with the ideas of mutation expressed by De Vries. This they may be; but to anyone familiar with analytical breeding the course of these experiments must seem so surprising as to call for most careful, independent confirmation. In 1910[10] Tower published an account of further experiments with _Leptinotarsa_. The work described related to two subjects. Crosses were made between three forms, _undecimlineata_ Stål, _signaticollis_ Stål and "_diversa_" named by Tower as a new species. The distinctions between these three depend partly on characters of the adults and partly on those of the larvae. The adults of _undecimlineata_ and _diversa_ have the elytra striped, but the elytra of _signaticollis_ are unstriped. The larvae of _signaticollis_ and of _diversa_ are yellow, but those of _undecimlineata_ are white.[11] Moreover, in _signaticollis_ and _diversa_ the black increases in the third stage of the larvae to form transverse bands which are absent in _undecimlineata_. The general course of the experiments shows that these differences may be approximately represented as due to the action of three factors, any of which may be independently present or absent. The stripings of the elytra and of the larvae are each due to a separate factor. As regards the distinction between the yellow and the white larvae the evidence does not prove that there is decided dominance of either colour and I infer that the heterozygotes are often intermediate. The chief contribution which this new paper claims to make relates to differences in the results which ensue from crosses effected between these three types at different average temperatures. We are first concerned with four experiments which I number (1), (2), (3), (4): 1. _Signaticollis_ [F] � _diversa_ [M] bred at an average temperature of 80º F. by day and 75° F. by night, gave two groups in about equal numbers. The first (49) was pure _signaticollis_ and bred true. The second (53) was of an intermediate type, which on being bred together gave the typical Mendelian result--1 _sig._: 2 _intermediate_: 1 _div_. 2. Next, as the account originally stood in the published paper, we are told that _sig_ [F] � _div_ [M] bred together at a day-temp. average 75° F. and night average 50° F. gave an _intermediate_ only, which subsequently produced a normal 1:2:1 ratio. The two crosses were repeated eleven times with identical results. In a further experiment (3) _signaticollis_ [F] � _diversa_ [M] were bred under the same conditions as those used in expt. (1). They again gave _sig._ and intermediates as before in fairly equal numbers. The _sig._ as before bred true, and the intermediate gave 1:2:1, all exactly as in expt. (1). In expt. (4) _the same parents used_ in (3) were again mated under conditions of expt. (2) at the lower temperature, and this time gave _signaticollis_ exclusively, which bred true for four generations. This experiment was repeated seven times with uniform results. Diagrams are given representing all these histories in graphic fashion. From these observations, Tower concludes that the determination of dominance, and the ensuing type of behaviour, is clearly a function of the conditions incident upon the combining germ plasms. It will be observed that expts. (1) and (3) gave identical results but (2) and (4), though much the same conditions were applied, are at variance, for (2) gave all intermediates, while (4) gave all _signaticollis_. In _Amer. Nat._, XLIV, 1910, p. 747, Professor T. D. A. Cockerell commented on this paper of Tower's and pointed out that there must be an error somewhere, for when he discusses these experiments Tower speaks of (2) and (4) as confirming each other. To this Tower replied[12] that there had been a mistake. He states that in preparing the paper "certain minor experiments were taken from a larger series and combined to illustrate a general point in the behaviour of alternative characters in inheritance," and that expt. (2) was introduced inadvertently in place of another which he desires to substitute. In this, which I number (5), _signaticollis_ [F] � _diversa_ [M] from exactly the same stocks as those used in (1), were mated at the lower temperatures specified for (2), day average 75° F., night average 50° F. These gave all of the _signaticollis_ type with a narrow range of variability, which bred true, in some cases to F_{6}. Tower says he has repeated this experiment six times with identical results. Nevertheless he proceeds to say that the description of expt. (2), which was repeated eleven times with identical results, was correct "as far as given." That experiment was "from a second series of cultures parallel to the one given, but in which there are other factors involved, which in H. 410 [my (2)] are productive of a typical Mendelian behaviour." He adds he does "not care at this time to make any statement of what these factors are, nor of their relations to the behaviours given in the H. 409, H. 411, H. 409/11 series [my (1), (5) and (3)--(4)] which are the simplest and most easily presented series obtained in the crossing of _signaticollis_ and _diversa_." Professor Cockerell's intervention has thus elicited the fact that we have as yet only a small selected part of the evidence before us, even as concerning the effect of temperature on the cross between _signaticollis_ [F] � _diversa_ [M]. We learn that at the lower temperatures the result was eleven times the expected one, and six times an unexpected one; further, that we owe it to the author's inadvertence that we have come to hear of the expected result at all, and that though he knows the factors which determine the discrepancy, he declines for the present to name them. In these circumstances we can scarcely venture as yet to estimate the significance of these records. The paper goes on to recount somewhat comparable, but more complex instances in which the descent of the colour of adults and of larvae was affected by temperature in crosses between _undecimlineata_ and _signaticollis_. As they stand the results are very striking and unexpected, but I think, in view of what has been admitted respecting the former part of the paper, full discussion may be postponed till confirmation is forthcoming. One feature, however, calls for remark. This second paper is written apparently without any reference to the discoveries related by Tower in his previous book, to which no allusion is made. This is most noticeable in the case of an experiment in which (p. 296, H. 700A) _undecimlineata_ [F] (the dominant) was mated to _signaticollis_ [M] with the result that all the offspring were _undecimlineata_ and bred true to that type (Parthenogenesis was tested for, but never found to occur). This experiment was made at a temperature averaging 95° F. ± 3.5° by day and 89° F. ± 4.8° by night, and in a humidity given as 84 per cent. by day and 100 per cent. by night; but in the previous book (p. 294) we are told that pure _undecimlineata_ bred together "under an extreme stimulus of high temperature, 10° C. above the average" and a relative humidity of 40 per cent. gave 11 beetles only, all _angustovittata_. But reference to the Plate 16, Fig. 2, shows that _angustovittata_ must be exceedingly like _signaticollis_, having, like it, the elytral stripes obsolete, and if there is any marked difference at all, it can only be in the larvae. It seems strange that if _undecimlineata_ really gives off ova of this recessive type at high temperatures, the fact should not be alluded to in connection with expt. H. 700A, where, as the father was _signaticollis_, having the same recessive character, their appearance might have been expected not to pass unobserved. The temperature in the older experiment is, of course, not given with the great accuracy used in the second, and it may have been higher still. The humidity also was widely different. Still, in discussing the phenomena we should expect some reference to the very remarkable and closely cognate discovery which Tower himself had previously reported in regard to the same species.[13] The hesitation which I had come to feel respecting these two publications of Tower's has been, I confess, increased by the appearance of a destructive criticism by Gortner[14] who has examined the parts of Chapter III of Tower's book, in which he discusses at some length the chemistry of the pigments in _Leptinotarsa_ and other animals. As Gortner has shown, this discussion, though offered with every show of confidence, exhibits such elementary ignorance, both of the special subject and of chemistry in general, that it cannot be taken into serious consideration. Some observations made by Dr. W. T. Macdougal[15] have also been interpreted as showing the actual causation of genetic variation by chemical treatment. Of these perhaps the least open to objection were the experiments with _Raimannia odorata_, a Patagonian plant closely allied to _Oenothera_. The ovaries were injected with various substances and from some of the seeds which subsequently formed in them a remarkable new variety was raised. This varying or mutational form was strikingly different from the parental type, with which it was not connected by any intergradational forms, and it bred true. It made no rosette, growing to a much smaller size than the parent, and was totally glabrous instead of being very hairy as the parental type is. I was shown specimens of these plants by the kindness of Dr. Britton in the Bronx Park Botanic Garden in 1907 and can testify to their very remarkable peculiarities. They had a somewhat weakly look, and might at first sight be thought to be a pathological product, but they had bred true for several generations. From the evidence, however, I am by no means satisfied that their original appearance was a consequence of the treatment applied. This treatment was of a most miscellaneous description. Two of the mutants came from an ovary which had been treated with a ten per cent. sugar solution. Ten came from one into which a 0.1 per cent. solution of calcium nitrate had been injected. One was from a capsule which "had been exposed to the action of a radium pencil." Macdougal speaks of these results as decisive, but clearly before such evidence can be admitted even for consideration it must be shown by control experiments that the individual plants which threw the mutant were themselves breeding true in ordinary circumstances. Nothing is more likely than that the mutant was an ordinary recessive. I may add that Mr. R. H. Compton made a number of experiments with _Raimannia odorata_, raised from seeds kindly given me by Dr. Britton, injecting the ovaries with a variety of substances, including those named by Macdougal; but though a numerous progeny was raised from the ovaries treated, all were normal. Macdougal relates also that some mutational forms came from ovaries of _Oenothera Lamarckiana_ exposed to radium pencils, and also from _Oenothera biennis_ injected with zinc sulphate a peculiar mutant was raised, but taking into account the frequency of these occurrences in those species, he very properly regarded this evidence as of doubtful application. In a later paper,[16] however, he has returned to the subject and affirms his conviction that the appearance of a mutant among seedlings raised from an ovary of _Oenothera biennis_ treated with zinc sulphate was really a consequence of the injection, saying that the variation previously observed in the species was afterwards shown to be due to fungoid disease. The circumstances to which he mainly points in support of his view is that the mutation bred true, but this is only evidence of its genetic distinctness, which may, of course, be admitted by those who remain unconvinced as to the original cause of its appearance. He adds that he is making similar experiments with some twenty genera; but what is more urgently needed is repeated confirmation of the original observation. When it has been shown that this mutation can be produced with any regularity from a plant which does not otherwise produce it on normal self-fertilisation, the enquiry may be profitably extended to other plants. A curious and novel experiment, which however, led ultimately to a negative result, was made by F. Payne. Many discussions have been held respecting the blindness of cave animals. The phenomenon is one of the well-known difficulties, and most of us would admit that the theory of evolution by the natural selection of small differences does not offer a really satisfying account of it. Those who believe in the causation of such modifications by environmental influences and in their hereditary transmission make, of course, the simple suggestion that the darkness is the cause of the loss of sight, and that disuse has led to the reduction of the visual organs. Payne bred _Drosophila ampelophila_, the pomace-fly (which is easy to keep in confinement, fed on fermenting bananas), for sixty-nine generations in darkness. At the end of that period there was no perceptible change in the structure of the eyes, or in any other respect. The number of generations may possibly be regarded as insufficient to prove anything, but comparing them, as he does, with the generations of mankind, we see that they correspond with a period of about two thousand years, an interval far longer than those which many writers in particular cases have deemed sufficient. In his first paper Payne states that, though no structural difference could be perceived, the flies which had been bred in the dark reacted less readily to light than those which had been reared under normal conditions, and he inclined to think that the treatment had thus produced a definite effect. After more careful tests, however, he withdrew this opinion. It proved that both individual flies and individual groups of flies, both of those bred in the light and of those bred in the dark, differed greatly in their reactions, which were measured by counting the time that it took for a fly to travel to the light end of a covered tube, various sources of error being eliminated. He found further that these differences of behaviour were not inherited in any simple way, but he is disposed to attribute them to accidental differences in the nature of the food, an account which seems probable enough.[17] In several recent publications Blaringhem[18] has described the origin of many abnormal forms of plants, especially of maize, which he attributes to various mutilations practised upon the parents. Respecting these the same difficulty which has been expressed in other cases reappears, that before drawing any conclusion as to the value of such evidence we require to know that the plants treated belong to a really pure line, which if left to nature in the ordinary circumstances of its life in that locality would have had normal offspring. Abnormalities abound in the experience of everyone who examines pans of seedlings of almost any species of plant, and in maize they are well known to be exceptionally common. Some of those which we meet with when we attempt to ripen maize in this country are very similar to those which Blaringhem describes, consisting in irregularities in the distribution of the sexes, in the shapes of the panicles, etc. Many of these are doubtless imperfections of development, due to the dullness of our climate, but others are presumably genetic and would recur in the offspring however treated. If some one working in a climate where maize could be raised in perfection would repeat these experiments, and show that a strain which was thoroughly reliable and normal in its genetic behaviour did, after mutilation, throw the miscellaneous types observed by Blaringhem, that would be evidence at least that the development of the seed could be so influenced by injury to the parental tissues that its properties were changed. Such evidence could be used for what it is worth; but pending an inquiry of this kind I am disposed to regard these observations of variation following on parental injury as suggestive rather than convincing. Some evidence of a remarkably interesting kind has been collected by J. H. Powers[19] respecting the structure and habits of _Amblystoma tigrinum_, which led him to the conclusion that striking differences in the form, anatomy, and developmental processes could be effected directly by change in the conditions of life. It is well known that a profusion of forms, distinct in various degrees, is grouped round _Amblystoma tigrinum_. Some of these are believed to be geographically isolated, others occur together in the same waters, and, as usual, authorities have differed greatly as to the number of names to be given. These forms were studied in detail by Cope who described them in the _Batrachia of North America_. The view which he inclined to take was that the individual variations of _Amblystoma tigrinum_ resulted from variations in the time and completeness of the metamorphosis, and these were regarded as due to external causes, such as differences in season, temperature, and geographical conditions. Powers, however, states that collecting within a radius of six or eight miles he found almost if not quite the whole "gamut of recorded variation in this species." Some, however, as he states, occurred rarely except under experimental conditions, but considerable differences in temperature were not found necessary in producing them. Every year, he says, he has been able to add to the number of peculiar types found in the same small area in nature, until the amount of natural variation at least equals that seen by Cope in the collections of the National Museum and those of the Philadelphia Academy. Powers states that his observations by no means confirm Cope's view that these differences are in the main referable to variation in the completeness of metamorphosis, and on the contrary, he regards metamorphosis as on the whole a levelling process, tending to obliterate diversity. The enormous differences in size and proportions which he describes can only be appreciated by reference to his figures. They affect almost all features of bodily organisation. These striking differences he looks upon as brought about by differences in nutrition, "diversities in habitual locomotion," and diversity in the age at which metamorphosis occurs, and to sexual difference. Apart from sexual difference he regards the chief distinctions, in brief, as "acquired variations of the larva." As an example he gives the great elongation of some of the forms as "due first to slow growth, second to the free-swimming habit, third to the prolongation of larval life, and finally to the assumption of sexual maturity as males," either in the branchiate or non-branchiate condition. He describes the rapid growth of some and the slow growth of others. A larva of intermediate type may grow about a centimeter a month, but a rapidly growing specimen may grow more than four times as much. The slower rate of growth may, he says, be induced by winter feeding, and other treatment.[20] When, however, he goes on to describe the influences which he regards as exerted by the habit of freely swimming, I am led to wonder whether after all in most of these illustrations, the primary distinctions are not in reality genetic. "Specimens raised in the same aquarium or in similar aquaria, side by side with all conditions as uniform as it is possible to make them, seldom fail to furnish striking examples of broad-headed, short-bodied, and short-tailed types which are habitually found at the bottom, while others, slender and elongated, are free swimmers, and maintain themselves in almost as continual suspension and motion as does a gold fish." Later, again, he writes, "Yet despite the uniformity of these favourable conditions, the larvae soon began to split up into two noticeably distinct groups, the one of unusually compact proportions, the other of uniform intermediate build, such is most commonly met with." It is to my mind scarcely possible to resist the inference that, though there may be definite responses to certain conditions, yet the chief distinctions are genetic, and that it is these distinctions which confer the power to respond. The parts respectively played by cause and effect are always difficult to assign; but when it is stated that "a weak-limbed, long-bodied and long-tailed animal becomes well nigh perforce an undulatory swimmer, while the strong-limbed, short-tailed, heavy-bodied specimen, when these characteristics are rapidly forced upon it, is, under certain circumstances, just as forcibly induced to become a crawler," we feel how erroneous any estimates of causation are likely to be. One of the most remarkable and interesting sections of Powers' paper is that in which he describes the differences in bodily structure and habits which he attributes to cannibalism, and the whole account of the phenomena should be read in the original. It appears that there are two extremely distinct types of larvae, those with narrow heads and slender bodies which live for the most part on small Crustacea such as _Daphnias_, and those with huge mouths and very wide heads, which disregard such small animals altogether and live on amphibian larvae, whether of their own or other species. As the illustrations show, the differences between these two types are very great, and the differences in instinct and behaviour are no less. The cannibals take no heed of the pelagic crustacea, lying sluggishly at the bottom, rousing themselves immediately to a violent attack on the larger living things which approach them. Nothing but the most incontrovertible evidence based on abundant control experiments should convince us that such differences are not primarily genetic, and in the present state of knowledge I incline to think that the families really consist of individuals which are ready to assume the cannibal habit if opportunity offers, and others which are congenitally incapable of it. It may readily be that if all chance of cannibal diet be excluded, the full development of the wide head and mouth, or the other peculiarities, would never become pronounced, but I doubt whether such change could be induced in any individual taken at random. FOOTNOTES: [1] Pringsheim, H., _Die Variabilität niederer Organismen_, Berlin, 1910. [2] F. Wolf, Modifikationen u. Mutationen von Bakterien, _Zts. F. indukt. Abstam. u. Vererbungslehre_, II, 1909, p. 90. [3] Winslow, C. E. A. and A. R., _Systematic Relationships of the Coccaceae_. New York. 1909. [4] C. C. Dobell, _Jour. Genetics_, 1912, II, p. 201, where full references are given. Still more recently the same author has contributed an excellent summary of the evidence relating to bacteria (_ibid._, II. 1913, p. 325). [5] See Woltereck, _Verh. d. Deut. Zool. Ges._, 1909, p. 110; and 1911, p. 142. This is a subject which can only be properly appreciated on reference to the original papers. Several complications are involved to which I have not here alluded. [6] _Proc. Roy. Soc._, B, Vol. 86, 1913, p. 113. [7] _An Investigation of Evolution in Chrysomelid Beetles of the Genus Leptinotarsa_, Carnegie Publications, 1906, No. 48. [8] This is the famous Colorado beetle or potato-bug, which has caused such serious destruction in potato crops. There seems to be no doubt that this insect, formerly unknown in the eastern States, made its way east along the mining trails when the west was opened up. [9] This is indicated in the coloured plate, but I have not found any explicit statement to this effect in the text, and am not sure if the absence of pigment was regarded as complete. [10] _Biol. Bull._, XVIII, 1910, p. 285. [11] This description does not quite agree with the representation of the larvae in Pl. 17 of the book _Evolution in the Genus Leptinotarsa_ for there the larva of _undecimlineata_ is shown as white in the second stage, but yellowish in the third stage; perhaps there is an error in printing. [12] _Biol. Bull._, XX, 1910, p. 67. [13] As to the interrelations of these three forms, Tower states (1906, p. 18) that _angustovittata_, which he reared from _undecimlineata_, is intermediate between it and _signaticollis_. Compare Stål, "_Monogr. des Chrysomélides_," 1862, p. 163; and Jacoby, _Biol. Centr. Amer. Celeopt._, vi, Pt. 1, p. 234, Pl. xiii, fig. 20; Tab. 41, fig. 15; _ibid._, Suppl., p. 253. All these forms are evidently very closely related, and the delimitation of species is quite arbitrary. Jacoby indeed suggests that _undecimlineata_ may be a variety of _decemlineata_. [14] Gortner, _Amer. Nat._, Dec., 1911, XLV, p. 743. [15] _Mutations, Variations, and Relationships of the Oenotheras_, Carnegie Institution Publication No. 81, 1907, pp. 61-64. [16] Macdougal, D. T., "Alterations in Heredity induced by Ovarial Treatments", _Bot. Gaz._, vol. 51, 1911, p. 241. [17] Payne, Fernandus, _Biol. Bull._, XVIII, 1910, p. 188, and _ibid._, XXI, 1911, p. 297. [18] See especially, _Mutation et Traumatismes_, Paris, Felix Alcan, 1908. [19] J. H. Powers, "Morphological Variation and its Causes in _Amblystoma tigrinum_." _Studies from the Zoological Laboratory. _ The University of Nebraska, No. 71, 1907. [20] In connexion with this case I would refer the reader to some remarkable observations of Dr. T. A. Chapman on various types of larvae which he reared from the moth _Arctia caja_ (_Ent. Rec._, IV, 1893, p. 265, and following parts). From a single mother he raised a great diversity of forms, some which fed up rapidly and passed through their development without assuming certain stages, and others which were, as he called them, "laggards," moulting more times than their brethren and developing at a much slower rate. It is greatly to be hoped that such a case may be critically investigated by analytical breeding. CHAPTER XI. STERILITY OF HYBRIDS. CONCLUDING REMARKS. When we consider the bearing of recent discoveries on those comprehensive schemes of evolution with which we were formerly satisfied, we find that certain details of the process are more easy to imagine. We readily now understand how varieties once formed, can persist, but at the same time difficulties hitherto faced with complacency become formidable in the light of the new knowledge. So generally is this admitted by those familiar with modern genetic research that most are rightly inclined to postpone the discussion. The premisses, indeed, on which such a discussion must be based are almost wholly wanting. The difficulties to which I chiefly refer are not those created by the phenomena of adaptation, though they are serious enough. In treating of that subject I have felt obliged to express scepticism as to the validity of nearly all the new evidence for the transmission of acquired characters. At the present time the utmost we are bound to accept is the proof that (1) in some parthenogenetic forms variations, or perhaps we may say malformations, produced in response to special conditions, recur in one or perhaps two generations asexually produced after removal to other conditions. (2) That violent maltreatment may in rare instances so affect the germ-cells contained in the parents as to cause the individuals resulting from the fertilisation of those cells to exhibit an arrest of development similar to that which their parents underwent. I do not doubt that evidence of this type will be greatly extended. As a contribution to genetic physiology these facts are very important and interesting, but I cannot think that any one, on reflexion, will feel encouraged by such indications to revive old beliefs in the direct origin of adaptations. In these respects we are simply left where we were. The force of objections based upon the existence of adaptative mechanisms is no greater than it has always been. On the contrary the fact that variations can now so generally be recognized as definite is some alleviation of the difficulty. We can moreover disabuse ourselves of the notion that for all characters which are definite or fixed, some utilitarian rationale may be presumed. Upon that point the study of variation has provided a perfectly clear answer. In frankly recognizing that the fixity of characters in general need not connote usefulness to their possessors we deliver ourselves of a distracting pre-occupation and prepare our minds for an investigation of the properties of living organisms in the same spirit as that in which the chemist and the physicist examine the properties of unorganized materials. The creature persists not merely by virtue of its characteristics but in spite of them, and the fact of its persistence proves no more than that on the whole the balance of its properties leaves something in its favour. It may be noted by the way that the fact that the structures of living things are on the whole adaptative was not always obvious. Though to naturalists of this generation it is a truism, we have only to turn to Buffon to find that in his philosophy of nature it played no essential part. The passage in which Buffon describes what he regards as the forlorn and degraded condition of the Woodpecker is well known. We have come to think of the Woodpecker as a capital example of adaptation to the mode of life; but Buffon after enumerating the hard features of the bird's existence, forced to earn its living by piercing the bark of trees in an attitude of perpetual constraint, remarks[1] "Tel est l'instinct étroit et grossier d'un oiseau borné a une vie triste et chétive. Il a reçu de la Nature des organes et des instrumens appropriés a cette destinée _ou plutôt il tient cette destinée même des organes avec lesquels il est né_" (my italics). His reflexions on the Stilt (_Himantopus_) read even more strangely to us, accustomed as we are to see in the prodigious length and thinness of the shanks and in the other features of its organisation palpable adaptations to a wading life. For Buffon, however, this curious bird seemed a poor, neglected production, extravagant in its disproportions, one of the misfits of creation, left as a shadow in the picture composed of nature's more successful efforts.[2] This theme he develops at some length, being evidently well pleased with the idea. Our way of regarding these things is doubtless sounder and more fruitful than Buffon's, but it is well to remember that what seems so obvious to us looked quite differently to other excellent observers; and stupid as it may have been to have overlooked plain examples of adaptation, it is a far worse mistake to see adaptation everywhere. I do not seek to minimise the real and permanent difficulty which the existence of adaptations creates, but by the suggestion that all normal specific differences are adaptational that difficulty was quite gratuitously increased. In these respects it may be claimed that progress has been made, even if that progress seem outwardly of small account. But all constructive theories of evolution have been built on the understanding that what we know of the relation of varieties to species justifies the assumption that the one phenomenon is a phase of the other, and that each species arises or has arisen from another species either by one or several genetic steps. In the varieties we have accustomed ourselves to think that we see those steps. We still know little enough of the mode of occurrence of variation, but we do begin to know something, and if we ask ourselves whether our knowledge, such as it is, conforms at all readily with our former expectations, we cannot with any confidence assert that it does. Among the plants and animals genetically investigated are many illustrations of very striking and distinct varieties. Many of these might readily enough be accepted as species by even the most exacting systematists, and not a few have been so treated in classification; but when we have examined their relationship to each other we feel not merely that they are not species in any strict sense but that the distinctions they present cannot be regarded as stages in the direction of specific difference. Complete fertility of the results of inter-crossing is and I think must rightly be regarded as inconsistent with actual specific difference; and of variations leading to that consequence no clear indication has yet been found. As an example of possible exceptions mention should perhaps be made of the case of a giant form of _Primula sinensis_ investigated by Keeble.[3] It arose from a "Star" Primula of normal size, and though fertile with its own pollen all attempts to fertilise it with the pollen of other forms failed. Miss Pellew, who did these fertilisations, tells me that very extensive trials were made, and repeated in several seasons. Ultimately two plants were raised from it fertilised with a plant of the strain from which it sprang, and these proved sterile. In the light of modern experience the significance of such isolated instances is doubtful. All the strains known as "Giants" are, as Messrs. Sutton have always found, more or less sterile, and their sterility is presumably due to some negative defect. In regard to the fertility of Primula species there are several paradoxes. For example the long-styled varieties, apart from giants, are fertile with their own pollen, and for many years short-styled plants have not been used in most strains. Auriculas and Polyanthuses, on the contrary, are generally if not always bred from short-styled plants, as the florists have decided that the long-styled are inadmissible. Mr. R. P. Gregory tells me that, though most strains of _P. sinensis_ give seed enough when only long-styled plants are used, he finds nevertheless that when a "legitimate" union is made the amount of seed usually increases much as Darwin observed. Darwin's statement that plants of "illegitimate" origin are less fertile than the "legitimately" raised plants is also in general confirmed by his experience. To this rule there were some marked exceptions in strains derived from _long_-styled plants, which though illegitimate showed a high degree of fertility, but illegitimate unions between _short_-styled plants always produced comparatively sterile offspring. I have no records of the behavior of Auriculas and Polyanthuses. It would be interesting to know whether among them pure strains of short-styled plants (dominants) have appeared, and, if so, how their fertility is affected. Without much more critical data I suppose no one would nowadays be inclined to follow Darwin in instituting a comparison between the sterility of hybrids and that of illegitimately raised plants of heterostyle species.[4] It is even difficult to imagine any essential resemblance between these two phenomena, nor has evidence ever been produced to show that illegitimately raised plants have bad pollen grains, which is the usual symptom of sterility in hybrid plants and the consequence, as we believe, of failure of some essential division in the process of maturation. The difficulty that we have no knowledge of the contemporary origin of forms, from a common stock, which when crossed together give a sterile product, is one of the objections constantly and prominently adduced from the time of the first promulgation of evolutionary ideas. In the light of recent work the objection has gathered strength. Why, if we are able to produce instances of variation colourably simulating specific difference in almost all other respects, do we never find an original appearance of this most widely spread of all specific characteristics? No doubt all breeders know that sterile animals and plants occasionally appear in their cultures, but it is more in accordance with probability that the sterility in these sporadic instances should be regarded as due to defect than that it should be thought comparable with that of the sterile hybrids. For their sterility must, by all analogy with results elsewhere seen, be attributed not to the absence of something, but to the presence and operation of complementary factors leading to the production of inhibition of division; and consistently with that interpretation, we find that when from a partially sterile hybrid comparatively fertile offspring can be raised, their comparative fertility continues in the posterity generally if not always without diminution. The distinction between these several kinds of sterility was of course not understood in Darwin's time. The comparison, for example, which he instituted[5] between the sterility of "contabescent" anthers and that of hybrids no longer holds, for at least in those cases in which the nature of contabescent anthers have been genetically investigated (Sweet Pea, _Tropaeolum_) they proved to be a simple recessive character. Nor can we now easily suppose that the attempt there made by Darwin to suggest resemblance between the sterility produced by unnatural conditions and that of hybrids has any physiological justification. In regarding the power to produce a sterile or partially sterile hybrid as a distinction in kind, of a nature other than those which we perceive among our varieties, I am aware that I am laying stress on an impression which may hereafter prove false. The distinction nevertheless is so striking and so continually before the eyes of a practical breeder that he can scarcely avoid the inference that when he meets a considerable degree of sterility in a cross-bred he is dealing with something belonging to a distinct category, and not merely a varietal feature of an exceptional kind. Besides the sterility of hybrids appeal has often been made to the phenomenon of incompatibility, in its several stages of completeness, as distinguishing species. No one doubts that incompatibility may arise from a variety of causes of most diverse degrees of importance, but though sometimes referred to as an extreme case of interspecific sterility, it is really a very different matter. In regard to one phase of this incompatibility, that associated with self-sterility, some progress has been made, and we are not wholly without experimental evidence of its being within the range of contemporary variation. Given the outline of Mendelian teaching as to gametic differentiation and the classification of individuals in a mixed population, it seemed highly probable that what we call self-sterility must mean that the species really consisted of _classes_, some of which are capable of interbreeding with others while others are not. According to the received account every individual, though incapable of fertilising itself, was supposed to be able both to fertilise and to be fertilised by any other individual. This notion has always seemed to me a self-evident absurdity, for it would imply that there can be as many categories as individuals. Such experiments, however, as I made did certainly give results consistent with that belief. I first tried Cinerarias, which are usually self-sterile, but I found no incompatible pairs of plants. Whether I was deceived by the consequences of apogamy, or whether the pollen of certain plants may belong to more than one class I do not know. The results were confused in various ways. Usually the self-fertilised plants set little or nothing, and cross-fertilised they set fully with such uniformity that the few failures could plausibly be attributed to mistakes in manipulation or to other extraneous causes. Later de Vries announced[6] (without giving particulars) that he had proved the existence of such classes in _Linaria vulgaris_; but on making experiments with that species I again got no positive results, and I came to the conclusion that in spite of inherent improbability the conventional belief must be substantially true. At last, however, the work of Correns, lately published,[7] does definitely show that in one species, _Cardamine pratensis_, classes of individuals exist such that individuals of the same class are incapable of fertilising themselves or each other, but fertilisation made between the classes is usually completely effective. Many complications were encountered and some contradictory evidence is recorded, but the general bearing of the results was positive and indubitable. We know far too little of this phenomenon as yet to be able to understand its significance, but I suppose we may anticipate with some confidence that it will be found to be a manifestation of dissimilarity between the male and female gametes of the same individual, comparable with that first seen in the Stocks (_Matthiola_) which throw doubles--a state of things in all likelihood to be found widely spread among hermaphrodite organisms. Whether the incompatibility between species is to be associated with that of the self-steriles also cannot be positively asserted, though it seems not unreasonable to expect that such an association will be discovered. The case of the apple and the pear is an impressive illustration of this possibility. The two species are of course exceedingly alike in all outward respects, but nevertheless the pollen of each is entirely without effect on the other. Presumably we should interpret this fact as meaning not so much that the apple and the pear are in reality very wide apart, but rather that either, each is lacking in one of two complementary elements, or that each possesses a factor with an inhibitory effect. Their incompatibility may well be of the same nature as that of the classes in _Cardamine pratensis_. Returning now to the problem of inter-specific sterility; we note, as I have said, the absence of contemporary evidence that variation can confer on a variety the power to form a sterile hybrid with the parent species. The considerations based on this want of evidence have for a long while been familiar to all who have discussed evolutionary theories, and it is worth observing the exact reason why the difficulty strikes us now with a new and special force. In pre-Mendelian times all that was known was that some forms could freely interbreed without diminution of fertility in the product, while others could not. But now we find that, by virtue of segregation, from one and the same pair of parents, or even, in the case of hermaphrodites, from one and the same individual, offspring commonly arises showing among themselves exactly such differences as distinguish species--and very good species too. This we see happening again and again. But to forms capable of arising as brethren in one family the title species has never been meant to apply, and if we are going to use the term in application to fraternal groups we must definitely recognise that by "specific" difference is to be understood simply _difference_, without any immediate or even ulterior physiological limitation whatever. Naturally, therefore, we begin to think of the appearance of sterility in crosses as something apart, and as a manifestation which distinguishes certain kinds of unions in a very special way. I am perfectly aware that there are gradations in the sterility of hybrids as in every other characteristic upon which it has been proposed to base specific definitions; but, as also so often happens in the matter of defining intergrading categories, the difficulty in practice is not often such as to lead to actual ambiguity. I am speaking of course of those examples which are amenable to genetic experiment. As to the rest there is complete and permanent uncertainty. But the experience of the practical breeder does, I think, on the whole, support the contention to which systematists have so steadily clung under all the assaults of evolutionary philosophers, that, though we cannot strictly define species, they yet have properties which varieties have not, and that the distinction is not merely a matter of degree. The first step is to discover the nature of the factors which by their complementary action inhibit the critical divisions and so cause the sterility of the hybrid. Thus expressed, we see the problem of inter-specific sterility in its right place; and the question why we do not now find contemporary instances of varieties lately arisen in domestication, which when crossed back with their parents, or with their coderivatives, can produce sterile products, is perceived to be only a special case of a problem which in its more general form is that of the origin of new and additional factors. For the requisite evidence no comprehensive search has been made, but perhaps it will yet be found. All that we can say at the present time is that the incidence both of hybrid sterility, and of incompatibility also, is most capricious; and provided that two forms have such features in common that a cross between them seems not altogether out of the question, no one can predict without experiment whether such a cross is feasible, and if feasible whether the product will be fertile, or sterile more or less completely. For instance, though probably all the British and some Foreign Finches (Fringillidae) have been crossed together, and some of these crosses, as for instance, the various Canary-mules have been made in thousands, I believe no quite clear example of a fertile hybrid can be produced. Many species of Anatidae cross readily and produce fertile hybrids: others give results uniformly sterile. Though most of the Equidae can be crossed and some of the hybrids are among the commonest of domesticated animals there is no certain record of a fertile mule. Among the Canidae the dogs, wolves and jackals all give fertile hybrids, but there is no clearly authenticated instance of a cross between any of these forms and the European fox. In spite of their close anatomical resemblance it is doubtful if the rabbit and the hare have ever interbred. Many of the wild species of _Bos_ have been crossed and recrossed both with each other and with many domesticated races, but I understand that no cross with the Indian buffalo (_Bos bubalus_) has yet been successful even in producing a live calf.[8] In the genus _Primula_ many hybrids are known and several of them occur in nature, but hitherto no certain hybrid between _P. sinensis_ and any other species has been made, in spite of repeated attempts. In _Nicotiana_ many--doubtless all--the various forms of _N. tabacum_ can be crossed together without diminution of fertility, though some are very distinct in appearance, but crosses between _tabacum_ and _sylvestris_ are highly sterile (in my experience totally sterile[9]), though the distinctions between them are not to outward observation nearly so great as those which can be found between the various races of _Primula sinensis_. Recently some remarkable experiments bearing closely on these questions have been published by F. Rosen.[10] They concern the forms of _Erophila (Draba) verna_, celebrated in the history of evolutionary theory as the plants especially chosen by Alexis Jordan for the exposition of his views on these subjects. The "species" contains a profusion of forms dissimilar in many structural characters, such as the size and shape of leaves, flowers, fruits, etc. Of these forms many grow in association. Jordan found, on experiment, that each, to the number of some two hundred, bred true, and that therefore, the conventional assumption that polymorphism of this kind must mean great contemporary variability had no foundation in fact. So far indeed is the evidence from favouring the belief that such forms are in any way transitional or indeterminate, that, as is well known, Jordan used it with every plausibility to support the doctrine of the fixity of species. To certain aspects of Jordan's work we will return later in this chapter, but the matter is in the present connection of especial interest for the reason that Rosen has lately found by experiment that some of these presumably very closely allied forms, crossed together, gave hybrids more or less sterile. In the case of the offspring of one pair of forms only (_E. cochleata_ and _stricta_) was the fertility undiminished, and the various degrees of sterility found in the other crosses ranged up to the extreme infertility of the hybrids between _E. stricta_ � _elata_. From this cross ten plants were bred. Of these the four strongest were chosen to breed from, but two of the four proved totally sterile; one had only bad seeds; and from the fourth a single seedling was raised which in its turn proved to be sterile. From the less sterile hybrids F_{2} families were raised, with the usual experience that in this and subsequent generations the sterility diminished among extracted forms, new and true-breeding types with complete fertility being thus derived from the original cross.[11] The production of sterility as a consequence of crossing plants so nearly approaching each other as these _Erophila_ "species" do is not a little interesting, and the fact well exemplifies the futility of the various attempts to frame general expressions as to specific properties or behaviour. Commenting on his results Rosen argues that the polymorphic group commonly called by systematists _Erophila (Draba) verna_ may now be regarded as having arisen by crossing, as did his own types mentioned above. The question, however, _what_ species were the original progenitors of the group cannot be answered. Rosen considers that no form which he knows satisfies the requirements, and that it or they must be supposed to be lost. This conclusion will recall the similar problem raised by the _Oenothera_ mutants (Chap. V); and unsatisfactory as it may be to have recourse to such hypotheses we must remember the possibility that as a consequence of hybridisation, subsequent segregation and recombination of factors, species may have thus actually, as we may say, exploded, and left nothing but a polymorphic group of miscellaneous types to represent them in posterity. If this way of regarding the phenomena be a true one, the sterility now seen when some of the group are re-crossed, becomes analogous to that "reversion or crossing" which we now so well understand to be a consequence of the recombination of characters separated at some previous point in the history of descent. In the partial sterility of the contemporary hybrid we see this character reappearing, formed now as it was on the occasion of the original cross, by the meeting of complementary factors. Another case that may be mentioned in this connection is that of the crosses between various culinary peas (_Pisum sativum_) and a peculiar form found by Mr. Arthur Sutton growing ostensibly in a wild state in Palestine. This Palestine Pea is low growing, rarely reaching 18 inches. It is in general appearance like a small and poorly grown field pea. The stems are thin and rather hard. The most obvious differences which distinguish this from other field peas are the marked serration of the stipules, and the development of pith in the pods. Such pith is often present in the pods of peas more or less, but in the Palestines it is so strongly developed as almost to form a lomentum. Curiously enough, though the flowers are purple much as those of ordinary field peas, there is no coloured spot in the axils. On the other hand, the stems have coloured stripes running up from the axils. Though this plant differs so little from domesticated peas, all crosses with them either failed, or produced hybrids quite or almost quite sterile. This was Mr. Sutton's experience, and on repeating the experiments with material kindly given by him I found the same result.[12] In a large series of crosses some seeds died or gave rise to feeble plants. Of the plants which lived, few gave any seed. The seed, however, that was obtained from F_{1} plants grew well enough, and the F_{2} plants proved, as often in such cases, fertile. In these, indeed, no sign of sterility was noticeable. The experiment is being repeated in various ways, for, as the genetic behaviour of peas is comparatively well known, the subject is an exceptionally favourable one for these investigations. Such an example shows the confusion produced the moment we attempt to harmonize conceptions of specific difference with results attained by experimental methods. It has been usual to regard the field pea (_P. arvense_) as a species distinct from the edible pea (_P. sativum_). De Candolle and others regard the field pea as derived from a form wild in Italy, but the origin of the edible pea is considered to be unknown. From breeding experiments we find no sterility whatever in the crosses between the various _arvense_ and _sativum_ types, nor in the crosses made between them and several other peculiar types from various countries; whereas this Palestine Pea, which only differs from a small _arvense_ in what might have been thought trivial characters,[13] either fails to cross altogether or gives a sterile product, whatever type be chosen as the other parent. Examples of this kind have at least the merit that they lead to more precise delimitations of the problem. We are confronted with two distinct alternatives. 1. We may apply the term Species promiscuously to all distinct forms. If we do so it must be clearly understood that we cannot even rule out the several combinations of "presences and absences" represented by the various types whether wild or domesticated. For we may feel perfectly assured that at least all the _arvense_ and all the _sativum_ types yet subjected to experimental tests are on precisely the same level in this respect. There is no distinction, logical or physiological, to be drawn between them. Some contain more factors, and others contain fewer. In some the re-combinations have been brought about by natural variation or crossing, while the same consequences in the others have resulted from man's interference. 2. We may follow the conventions of systematists and distinguish the outstanding or conspicuous forms such as _arvense_, _quadratum_, _sativum_ and perhaps a few more as species, and leave the rest unheeded. If this course is followed it must be clearly understood and permitted as a piece of pure pragmatism, deliberately adopted for the convenience of cataloguers and collectors, without regard to any natural fact or system whatsoever. But while following either the one plan or the other we shall be still awaiting the answer, which only genetic experiment can provide, to the question whether among the various types there are some which differ from the rest in a peculiar way: whether by having groups of characters linked together in especially durable combinations, or by possessing ingredients which cause greater or less disturbance in the processes of cell-division, and especially in the processes of gametic maturation, when they are united by fertilisation with complementary ingredients. Before any but the vaguest ideas regarding the nature and significance of inter-specific sterility can be formed, a vast amount of detailed work must be done. Sterility as a result of crossing, as well as that which is alleged sometimes to arise in consequence of changed conditions, is at best a negative characteristic, and there are endless opportunities for mistake and misinterpretation in studying features of this kind. No one, I suppose, would now feel any great confidence in most of the data which from time to time are resuscitated for the purpose of such discussions. Even the best collections of evidence, such as those given by Darwin in _Forms of Flowers_, cannot be regarded as critical when judged by present-day standards. Nothing short of the most familiar acquaintance with the habitual behaviour of individuals, and of strains kept under constant scrutiny for several years would enable the experimenter to form reliable judgments as to the value to be attached to observations of this class. The admission must, however, be faced that nothing in recent work materially tends to diminish the surprise which has always been felt at the absence of sterility in the crosses between co-derivatives. We should expect such groups of forms to behave like the _Erophila_ types, and frequently to produce sterile products on crossing. Whatever be the explanation, the fact remains that such evidence is wanting almost completely. In spite of all that we know of variability nothing readily comparable with the power to produce a sterile hybrid on crossing with a near ally, has yet been observed spontaneously arising, though that characteristic of specificity is one of the most widely distributed in nature. It may be that the lacuna in our evidence is due merely to want of attention to this special aspect of genetic inquiry, and on the whole that is the most acceptable view which can be proposed. But seeing that naturalists are more and more driven to believe the domesticated animals and plants to be poly-phyletic in origin--the descendants, that is to say, of several wild forms--the difficulty is proportionately greater than it was formerly, when variation spontaneously occurring was regarded as a sufficient account of their diversity. CONCLUDING REMARKS. The many converging lines of evidence point so clearly to the central fact of the origin of the forms of life by an evolutionary process that we are compelled to accept this deduction, but as to almost all the essential features, whether of cause or mode, by which specific diversity has become what we perceive it to be, we have to confess an ignorance nearly total. The transformation of masses of population by imperceptible steps guided by selection, is, as most of us now see, so inapplicable to the facts, whether of variation or of specificity, that we can only marvel both at the want of penetration displayed by the advocates of such a proposition, and at the forensic skill by which it was made to appear acceptable even for a time. In place of this doctrine we have little teaching of a positive kind to offer. We have direct perception that new forms of life may arise sporadically, and that they differ from their progenitors quite sufficiently to pass for species. By the success and maintenance of such sporadically arising forms, moreover, there is no reasonable doubt that innumerable strains, whether in isolation or in community with their co-derivatives, have as a fact arisen, which now pass in the lists of systematists as species. For an excellent account of typical illustrations I would refer the reader to the book lately published by R. E. Lloyd[14] on the rat-population of India. The observations there recorded are typical of the state of things disclosed whenever the variations of large numbers of individuals are closely investigated, whether in domestication or in natural conditions. Guided by such clues we may get a good way into the problem. We see the origin of colourable species in abundance. Then, however, doubt arises whether though these new forms are as good species as many which are accepted as such by even cautious systematists, there may not be a stricter physiological sense in which the term species can be consistently used, which would exclude the whole mass of these _petites espèces_. If further we find that we have, with certain somewhat doubtful exceptions, never seen the contemporary origin of a dominant factor, or of inter-racial sterility between indubitable co-derivatives, it needs no elaboration of argument to show that the root of the matter has not been reached. Examination of the inter-relations of unquestionably distinct species nearly allied, such as the two common species of _Lychnis_, leads to the same disquieting conclusion, and the best suggestion we can make as to their origin is that _conceivably_ they may have arisen as two re-combinations of factors brought together by the crossing of parent species, one or both of which must be supposed to be lost. All this is, as need hardly be said, an unsatisfying conclusion. To those permanently engaged in systematics it may well bring despair. The best course for them is once for all to recognise that whether or no specific distinction may prove hereafter to have any actual physiological meaning, it is impossible for the systematist with the means at his disposal to form a judgment of value in any given case. Their business is purely that of the cataloguer, and beyond that they cannot go. They will serve science best by giving names freely and by describing everything to which their successors may possibly want to refer, and generally by subdividing their material into as many species as they can induce any responsible society or journal to publish. Between Jordan with his 200 odd species for _Erophila_, and Grenier and Godron with one, there is no hesitation possible. Jordan's view, as he again and again declares with vehemence, is at least a view of natural facts, whereas the collective species is a mere abstraction, convenient indeed for librarians and beginners, but an insidious misrepresentation of natural truth, perhaps more than any other the source of the plausible fallacies regarding evolution that have so long obstructed progress. Nevertheless though we have been compelled to retreat from the speculative position to which scientific opinion had rashly advanced, the prospect of permanent progress is greatly better than it was. With the development of genetic research clear conceptions have at length been formed of the kind of knowledge required and of the methods by which it is to be attained. If we no longer see how varieties give rise to species, we may feel confident that a minute study of genetic physiology of varieties and species is the necessary beginning of any critical perception of their inter-relations. It is little more than a century since no valid distinction between a mechanical mixture and a chemical combination could be perceived, and in regard to the forms of life we may well be in a somewhat similar confusion. As yet the genetic behaviour of animals and plants has only been sampled. When the work has been done on a scale so large as to provide generalisations, we may be in a position to declare whether specific difference is or is not a physiological reality. FOOTNOTES: [1] Buffon, _Hist. Nat._, Oiseaux, 1780, VII, p. 3. [2] Ibid., VIII, p. 115. [3] Keeble, _Jour. Gen._, 1912, II, p. 173. [4] _Animals and Plants_, ed. 1, 1868, II, pp. 180-5. [5] _Animals and Plants_, ed. 1, 1868, II, p. 165. [6] _Species and Varieties_, 1905, p. 471. [7] Correns, _Festschr. med.-nat. Ges. zur 84 Versamml. Deutsch. Naturf. u. Aertze. Münster i. W._, 1912. [8] This is a case of a somewhat different order and I mention it partly for that reason as an illustration of the complexity which such negative instances may present. The difficulty is that though the buffalo and the zebu can breed together, the foetus is too large to be born alive. (See Ackermann _Ber. d. Ver. f. Naturk._, Kassel, 1898, p. 69. Prof. S. Nathusius, of Halle, who has great experience in crossing Bovidae, tells me that he has always failed to cross the buffalo with other species.) [9] In a paper to be published in the Report of the Genetic Conference, Paris, 1911, Bellair states that he obtained some partially fertile hybrids in the cross _N. sylvestris_ � _tabacum_. As to the various degrees of sterility in hybrids between _Nicotiana_ species see Lock, R. H., _Ann. Roy. Bot. Gardens_. Peradeniya, IV, 1909, p. 195. [10] _Beitrage zur Biol. der Pflanzen._, X, 1911, p. 379. [11] One very peculiar feature was observed, namely, that all the new forms in F_{2} which were bred from came true. As I understand, this statement applied to five such new types, and they were represented by 76 individuals in F_{3}, but further details on this point are desirable. Another curious fact was observed, namely that one of the F_{1} forms (_cochleata_ � _radiata_) when fertilised by _cochleata_ gave a highly polymorphic family, but fertilised by _radiata_ the resulting offspring were almost uniform. [12] I also had a few F_{1} seeds given me by Mr. R. H. Lock. [13] In a paper about to appear in _Jour. Linn. Soc._ Mr. A. W. Sutton identifies this Palestine pea as _Pisum humile_ of Boissier and Noé. [14] Lloyd, R. E., _The Growth of Groups in the Animal Kingdom_, London, 1912. INDEX OF SUBJECTS PAGE Abraxa grossulariata, 105,193 Aceras hircina, local variability, 123 Achatinellidae, local forms of, 133 Acquired characters, inheritance of, 188 et seq.,217,233 Acronycta psi, melanic, 138 Adaptation, problem of, 187,234 Agelaius, local forms, 120 Agrotis, fixed and variable species, 25 Alkaptonuria, 83 Alpine Plants, growing larger, if protected, 183 Alpine Varieties, 165 Alytes obstetricans, Kammerer's experiments on, 199,210 Amblystoma, races of, 230 Amphidasys betularia, melanic form, 136,138 dimorphic larvae, 141 Anodonta, polymorphism of, 130 Antirrhinum, striped, 57 species-hybrids, 99 albinos, 110 Apple, will not cross with pear, 239 Arctia caja, effects of temperature, 192 larval variation in, 231 Arctic varieties, 165 Argynnis paphia and valesina in Italy, 121 Armadillo, polyembryony, 42 Artistic faculty, 89 Arum, rights and lefts, 57 Auriculas, short-styled selected, 236 Axis of symmetry in hand and foot, 48 Axolotl, alleged effect of conditions, 230 Azalea, bud-sports, 55 Bacillus anthracis, unsegmented form, 71 Bacillus prodigiosus, variation in, 213 Bacteria, variation in, 212 Bacterium coli, variation in, 214 Baeolophus, geographical races of, 159 Barley, right and left-handed, 58 Basilarchia, geographical races of, 161 Begonia phyllomaniaca, 50 hybrids, 51 Bizarre Carnation, genetics of, 54 Black, as a variation from red, 148 Blackbird, varying, 150 Black Cock, fixity of, 28 Boarmia repandata, melanic form, 136 rhomboidaria, 137,139 Botrytis susceptibility to, 108 Bovidae, hybrid, 242 Brachydactyly, 89,95 Bradypus, vertebral variation, 68 Bud-sports geometrically irregular, 54-57 Buffalo, attempts to hybridize, 242 Bullfinch, gynandromorph, 45 Bulimus detritus, local variation of, 126 Canary, asymmetrical markings in, 154 Canidae, hybrid, 241 Capsella, 100 Cardamine pratensis, 239 Cat, Polydactylism, 53 Carnation, Picotees and bizarres compared, 54,58 Cataract, hereditary, 89 Certhiola, melanic, 142 Chladni figures, 60 Choloepus, vertebral variation in, 68 local variation in, 119 Cinerarias, self-sterility in, 238 Cistudo, local variation in, 119 Climatic varieties, 164 Coccaceae, variation in, 213 Coenonympha arcania, climatic forms of, 179 satyrion, 180 Coereba, melanic, 142 Colaptes, geographical races, 147 et seq. chrysoides, 154 Colloids, growth in, 65 Colorado beetles, experiments on, 218 Colour blindness in twins, 44 Continuous variation, possible example of, 173 Coracias, geographical races of, 160 Cotton, genetics of, 98,100 Coupling, 110 Crab, extra claws, 74 Crustacean appendages and Serial Homology, 63 Crystals, analogy with, 78 Cyclopian monsters, artificial, 50 Daphnia, changed by environment, 216 Dasypus, polyembryony, 42 Dianthoecia, fixed and variable species, 25 Disease-resistance, 87 Division, power of, a fundamental attribute of living things, 38 Genetics of, 46,50 Dogger Bank, large varieties on, 125 Dogs, hybrid, 241 Dominance, nature of, 95 Dominants, origin of new, 88,90,95 Double monsters, 42 Draba, experiments with, 242 Drosophila, 91 Payne's experiments on, 228 Earthworm, regeneration, 77 Elephant, tusk segmented, 38 Entelechy, 80 Environmental treatment, effects of, 188 et seq. Enzymes and genetic factors, 86 Epilepsy, inheritance of traumatic, 197 Equidae, sterility of hybrid, 241 Erophila, experiments with, 242 species, 249 Exacum, right and left, 57 Euphonia elegantissima, local forms, 120 Eupithecia rectangulata, melanic form, 137 Factors, new, 88 loss of, 96 Factorial representation of varieties, 158,165 Falcons, geographical races, 147 Fasciation, 49 Ferments, Boyle on, 54 Finger-prints of twins, 44 Fixity and Variability in species, 25 Flax, climatic experiments, 197 Fowl, Silky, 84 Leghorn, 85,90 Dominant white, 94 Wyandotte, 97 Rumpless, 46 Foxes, incompatibility with dogs, 241 Free-martin, 44 Fringillidae, sterility of hybrid, 241 Fundulus, cyclopian, 50 Gallus, invariability of wild species, 13 and origin of poultry, 90,97 Genitalia, a basis for classification in insects, 13 Gentians, climatic experiments, 197 Geometrical structure and differentiation, 54,56 Geometrical distinction between germ-cells and somatic cells, 58 Gladiolus, right and left, 57 Gnophus obscurata, protective colouring, 141 Goldfinch, geographical races, 147 Gonioctena variabilis, variation in sexes of, 121 Gouldian Finch, polymorphism, 148,149 Gracilaria stigmatella, experiments on, 193 Grantia, large varieties of, 125 Ground-Squirrels, local forms of, 132 Grouse, red, variation, 29 Guillemot, Ringed, 150 Guinea-pig, Brown-Séquard's experiments on, 198 Gynandromorphs, 45 Heliconius erato, forms of, 122,164 Helix lapicida, local variation of, 126 striata, 127 Heripensis, 127 Caespitum, 127 trochoides, 127 nemoralis and hortensis, 128 Helminthophila, geographical races of, 157 Hemerophila abruptaria, melanic, 142 Hepialus humuli, in Shetland, 119 Heterostyle plants, 236 Hieracium, 9 Himantopus, 234 Homoeosis, 68 Hybernia progemmaria, 139 Hybrids, sterility of, 233 et seq. Incompatibility between certain allied species, 239 Individual, geometrical independence of, 58 Inhibiting Factors, 95 Intermediates, nature of, 131,135 Isolation, consequences of, 118 Lacerta muralis, Kammerer's experiments on, 209 fiumana, 210 Leptinotarsa, Power's experiments on, 218 Limbs, extra, in pairs, 72 Limnaea, sinistral, 134 Linaria vulgaris, self-sterility, 239 Loasa fruits, right and left, 57 Lobster, extra claws, 76 Locality, variation connected with, 14,118,146 et seq.,208 Lumbricus, regeneration, 77 Lychnis dioica and vespertina, inter-relations of, 18 macrocarpa, possibly a common parent of, 19 Machetes pugnax, polymorphism of male, 28 Maize, Blaringhem's experiments on, 229 Maize, cumulative factors in, 116 Malformations, dominants, arising de novo, 89 Manx Cat, heredity, 46 Matthiola, 84,104,113 Melanic varieties, 135 et seq. Memory, analogy with heredity, 190 Meristic variation, 69,83,86 Mirabilis, striped, 57 Models of segmentation, 59,60 "Modes," Coutagne's conception of, 126 Mödling, peculiar race of _Pieris napi_ at, 178 Mole, albino, 27,28 Mule, Linnaeus on, 8 Mutation, Matthioli on, 4 in Mercurialis, 5 in Kales, 5 alleged in bulbs, 5 Theory, 97 periods of, 114 in Bacteria, 214 Mutilation, consequences of, 71 alleged effect of, on offspring, 229 Myxococcus, variation in, 213 Narwhal, asymmetry of tusks, 44 Nemesia strumosa, 91 Neuration, a basis for classification, 13 Nicotiana, sterility of hybrid, 242 Nightjars, varying, 150 Noctuidae, fixity and variability, 25 Noctua, polymorphic and fixed species, 25 Noctua castanea, local forms of, 122 Nomenclature, future of, 94,245 Notonecta, variations of, 130 Odontoptera bidentata, melanic form, 137 Oedipodidae, protectively coloured, 140 Oenothera, new dominant in, 92 rubricalyx and rubrinervis, 92,95 Lamarckiana, 92,101 origin of, 102,244 has bad pollen-grains, 102 factorial analysis of, 103 pollen and egg-cells genetically dissimilar, 104 Oenothera, "twin hybrids", 105 laeta and velutina, 105 reciprocal crosses in, 105 et seq. possible coupling in, 111 dwarfs, 112,114 "Triple hybrids", 114 alleged variation due to treatment, 227 Ophrys, local variability, 125 Orange, polyembryony, 45 Osmotic growth, 65 Overlapping forms, 146,174 Papilio, geographical races of, 162 Papilio turnus, variation of, 144 Pararge egeria, geographical forms, 166 et seq. Parthenogenesis, 50 Partula, local forms of, 133 Passer domesticus and montanus, distinctions, 22 Pea, round and wrinkled, 95 Pear, will not cross with apple, 239 Pelargonium, variegated, 55 bud-sports, 56 Periodic phenomena in structure, 63 Peronea, fixed and variable species, 26 "Petites espèces", 248 Petunia, double, 104 Phalanger maculatus, local variation, 119 Pheasant, fixity of, 29 Phigalia pilosaria, melanic, 139,140 Phratora vitellinae, experiments on, 193 Phyllotaxis, 69 Pied varieties common in Passer domesticus unknown in Montanus, 23 Pieris napi and bryoniae, 174 et seq. Pig, mule-footed, 46 Pigeon, web-footed, 46,49 Indian Rock, a recessive form, 98 Pigments, nature of, 83 Pisum humile, hybrids with culinary peas, 244 species, 246 Planarian, regeneration of, 71,77 Plotheia frontalis, polymorphic, 26,29 Plusia, fixity and variation in, 26 Poephila gouldiae, variation of, 148,149 Polarity of individual, 44 Polia chi, melanic, 138 Polyanthus, short-styled selected, 236 Polydactylism in Cat, 52,53 Polyembryony, 45 Potato, variation in, 91 Poultry, evolution of, 90 Primula obconica, 91 Primula sinensis, flaked, 57 Leaf-shapes, 70 new dominant in, 92 sterility in, 236 "Giants", 236 Primula, species-hybrids, 242 Protective coloration, 140 Pyrrhulagra, local forms, 120 Python, twin-vertebrae, 60 Quiscalus, geographical races of, 156 Rabbit, Angora, 46 colours of, 93 Incompatibility with hare, 242 Raimannia odorata, Macdougal's experiments on, 226 Rats, Variation in, 248 Recessives, origin of, 90 Reciprocal crosses, giving distinct results, 105 et seq. Regeneration, 70 Repulsion, 110 Reversal on Regeneration, 77 Rhamphocoelus, geographical forms, 159,184 Rhinoptera, variation in jaws of, 38 Rhythm in repetition, 69 Ribs, variation of, 68 Rights and Lefts, 57-58 Ripples, analogous to segments, 60,66,67 regeneration of, 79 Rollers, geographical races of, 160 Ruff, polymorphism of male, 28 Salamandra, maculosa and atra, 182,199,203 spotted and striped, 207 geographical variation of, 208 Segmentation, nature of, 63 simulated mechanically, 64 compared with rippling, 65 analogies with, 68 Segmentation of normally unsegmented structures, 38 Selection, Natural, an insufficient cause of definiteness of types, 17,134,142 Sempervivum, 250 Serial Homology, the true nature of, 62,66 Setina, Alpine varieties, 181 Sex of Twins, 44 Sex-factors, possible coupling of, 111 Sexual characters, variation in, 119 et seq. Siamese twins, 44 Silky Fowl, 84,85 Simocephalus, changed by environment, 218 Sinistral forms, 33-34 Situs transversus, 43 Skate's jaws, variation in, 38 Sloths, vertebral variation, 68 Species, conceptions of, 3,94,99,240,245 allied, distribution of, 185 alternative uses of the term, 245 Specific difference, universality of, 12 of organisms compared with those of inorganic materials, 15 failure of theory of Selection to explain, 18,134,247 Sphyropicus varius, 149,156 Spilosoma lubricipeda, varieties of, 181 Zatima, Heligoland form, 181 Spinal nerves, segmentation of, 67 Sporadic variation, 131,134,248 Squashes, polymorphism of, 100 Staphylococcus pyogenes, variation in, 213 Sterility of hybrids, in general, 233 in Lychnis hybrids, 20 et seq. in crossing forms of Draba, 243 Significance of, 244 Self, 238 Stilt, 234 Stocks, 84,104,113 Striped varieties, 57 Substantive variation, 84 Subtraction-stages, 93 Supernumerary limbs, 72-76 Sweet pea, variation of, 91 sterile anthers in, 237 Symmetry compared with heredity, 41 Symmetry of body approximate, 78 Syndactyly, 47 in foot, 48 Synthetic formulae, in nomenclature, 94 Taeniocampa, fixed and variable species, 25 Tamias, local forms of, 132 Tanagers, geographical races of, 159 Teeth, variation in, 67,39 Tephrosia consortaria and consonaria, 137,139,140 Tephrosia species, separated by season, 119 Terminal members, variation of, 68 Thais rumina, local variation in, 27 Tolerance, persistence of diversity due to, 17,134 Tomato, number of cells in fruit, 46 Transitional populations, rarity of, 165 an example, 178 Tropaeolum, sterile anthers in, 237 Trypanosomes, variation in, 215 Tusk, of Elephant, segmented, 38 of Narwhal, 44 Twinning, 41,44,71 heredity of, 45 in organs, 46 Uria troile, variety of, 150 Vanessa urticae, effects of temperature, 191 Variation, a medley of phenomena, 14,15 sporadic, 131,134 and locality, 118 Causes of genetic, 86,87,131,212 Substantive and meristic, 83 Veronica, specific difference in, 16 intermediates between species, 17 Vertebrae, division in, 60,61 homologies of, 66 Vespa, specific difference in, 23 Vortex, living organism compared with, 40 Wave-motion compared with repetition of parts, 62,67,79 Wheat, cumulative factors in, 116 climatic experiments on, 195 Woodpecker, 234 Zebra, pattern of stripes compared with ripples, 38 INDEX OF PERSONS PAGE Ackermann, 242 Agar, 218 Allen, J. A., 132,147,159 Annandale, 47 Arrigoni degli Oddi, 167 Backhouse, 50 Baker, G. T., 166 Bangs, Outram, 120,142,155 Barrett, 26,136,167,173,178,193 Baur, E., 55,99 Baur, G., 119 Beneden, van, 75 Bentham, on species of Veronica, 16 Lychnis, 21 Primula, 22 Bernadin, 42 Bishop, L. B., 153,157 Blaringhem, 229 Bobart, 5 Boisduval, 182 Boissier, 19 Borradaile, 74,75 Boulenger, E. G., 208 Boulenger, G. A., 182,207,209 Boyle, 5,54 Brewster, W., 149,150 Britton, 227 Brown, T. Graham, 198 Brown-Séquard, 197 et seq. Bruant, P., 51 Buffon, 234 Butler, S., 189,190 Buysson, R. du, 24 Candolle, de, 245 Carpenter, J. H., 172 Chapman, F. M., 148,156,157,158 Chapman, T. A., 13,167,182,231 Church, A. H., 69 Cieslar, 197 Clark, Austin, 142,144 Cockayne, E. A., 43 Cockerell, T. D. A., 224 Compton, R. H., 50,58,227 Cope, 230 Cory, 142 Correns, 239 Coutagne, 125 et seq. Darwin, on Variation, 1,2 Systematics, 10 Selection, 134,139 Heterostyle plants, 236,237 Darwin, F., 190 Darwin, Sir G., 41 Davenport, 46 Davis, H. M., 102 Delcourt, 130 Deschange, 181 Dobell, 215 Doncaster, 105,121,136 Driesch, 80,81 Duchartre, 51 East, 91,116 Edwards, W. H., 162 Ehrlich, 215 Fellmer, 215 Field, W. L. W., 161 Fischer, E., 192 Fleck, 171,174 Fletcher, W. H. B., 26,181 Foster, Sir N., 39 Gallé, 123 Garrod, 83 Gates, 92,95,102 Gayner, F., 177 Godron, 249 Gold, E., 196 Goldschmidt, 116 Goodwin, E., 137 Gortner, 226 Greene, E. L., 8 Gregory, R. P., 92,100,236 Grenier, 249 Grover, 173 Gruber, 48 Gulick, 119,133 Hamling, 142 Hampson, Sir G., 26 Harris, 142 Hartlaub, 182 Herbst, 42 Heribert-Nilsson, 116 Hewett, 182 Honing, 105 Hunter, John, 44 Jakowatz, 197 Janet, 24 Jeans, 41 Jenkinson, 40 Jentink, 120 Johannsen, 195 Jordan, 185,242,249 Kammere, 199 et seq. Keeble, 236 Klebs, 250 Krancher, 182 Küchenmeister, 44 Kudicke, 215 Lamarck, 9 Lang, A., 128 Lawrence, W. N., 142,145 Leake, H. Martin, 98,100 Leavitt, 185 Lecoq, 99 Lederer, 167 Leduc, 64,65,80 Leydig, 182 Linden, M. von, 192 Linnaeus, 6,7,8 Lloyd, R. E., 248 Locard, 130 Lock, R. H., 242,244 Loeb, 42,45,50,71,77 Lotsy, 99 Lowe, P. R., 143 Macdougal, W. T., 102,226 Marchant, 7 Mathew, 171 Matthioli, 4 Mayer, A. G., 133 Mendel, Rediscovery of, 2 On Fasciation, 49 Merrifield, 169, 172 Miller, W. D., 120,149 Morgan, 71,77,91,198 Moggridge, 125 Nathusius, S., 242 Nettleship., 44 Newman, H. H., 42 Newsholme, 48 Nilsson-Ehle, 116,169 Norman, A. M., 125,156 Ober, 142 Oberthür, 168,170,193 Oliver, J., 45 Page, H. E., 167,180 Patterson, J. T., 42 Payne, F., 278 Pellew, 236 Poll, 45 Porritt, 136 Poulton, 141 Powers, J. H., 230 Pringsheim, H., 213 Przibram, 72,78,178,194,197,199 Punnett, 110 Ray, 4,5 Raynor, 105 Ridgway, 10,120 Roedelius, 195 Rolfe, 20 Rosen, F., 242 Rosner, 42 Rowland-Brown, H., 167,180 Sargent, 185 Saunders, E. R., 84,104,112 Schima, 177 Schröder, 193,194 Schübeler, 195 Semon, R., 190 et seq. Sharrock, 5 Shull, 100 Speyer, A., 166,170,181 Spillman, 47 Standfuss, 135,181,191 Staples-Browne, 49,98 Staudinger, 170,179 Stockard, 50,71 Sutton, 236,244 Tornier, 72 Tower, W. L., 218-226 Trechmann, 133 Tugwell, 181 Tutt, J. W. On Definiteness of Species, 13 On Plusia interrogationis, 26 On Tephrosia, 119 On N. castanea, 122 On Pararge egeria, 167 et seq. Verity, R., 171,177 Vries, H. de, 101-115,222,239 Walker, G, 49 Weir, Jenner, 119 Weismann, 176,188 Wendelstadt, 215 Werbitzki, 215 Werner, 209 Wettstein, 197 Wheeler, G., 168,171 Wheldale, 83 Wilder, 44 Wille, 197 Williams, H., 167,172 Windle, B. C. A., 43 Winslow, 213 Wolf, F., 213 Woodforde, 123 Woltereck, 215 Zeijlstra, 114 
5273	----	DARWINIANA ESSAYS AND REVIEWS PERTAINING TO DARWINISM BY ASA GRAY FISHER PROFESSOR OF NATURAL HISTORY (BOTANY) IN HARVARD UNIVERSITY NEW YORK: 1876. CONTENTS DARWINIANA PREFACE ARTICLE I THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION Views and Definitions of Species--How Darwin's differs from that of Agassiz, and from the Common View--Variation, its Causes unknown.--Darwin's Genealogical Tree--Darwin and Agassiz agree in the Capital Facts--Embryology--Physical Connection of Species compatible with Intellectual Connection--How to prove Transmutation.--Known Extent of Variation--Cause of Likeness unknown--Artificial Selection.--Reversion--Interbreeding--Natural Selection.--Classification tentative.--What Darwin assumes.--Argument stated.--How Natural Selection works.--Where the Argument is weakest.--Objections--Morphology and Teleology harmonized.--Theory not atheistical.--Conceivable Modes of Relation of God to Nature ARTICLE II DESIGN VERSUS NECESSITY-- A DISCUSSION How Design in Nature can be shown--Design not inconsistent with Indirect Attainment ARTICLE III NATURAL SELECTION NOT INCONSISTENT WITH NATURAL THEOLOGY PART I.--Premonitions of Darwinism.--A Proper Subject for Speculation.--Summary of Facts and Ideas suggestive of Hypotheses of Derivation Part II--Limitations of Theory conceded by Darwin.--What Darwinism explains.--Geological Argument strong in the Tertiary Period.-- Correspondence between Rank and Geological Succession--Difficulties in Classification.--Nature of Affinity.--No Absolute Distinction between Vegetable and Animal Kingdoms.--Individuality.--Gradation PART III.--Theories contrasted.--Early Arguments against Darwinism.--Philosophical and Theological Objections--Theory may be theistic.--Final Cause not excluded.--Cause of Variation unknown.--Three Views of Efficient Cause compatible with Theism.--Agassiz's Objections of a Philosophical Nature.--Minor Objections.--Conclusion ARTICLE IV SPECIES AS TO VARIATION, GEOGRAPHICAL DISTRIBUTION, AND SUCCESSION Alphonse De Candolle's Study of the Oak Genus.--Variability of the Species.--Antiquity.--A Common Origin probable.--Dr. Falconer on the Common Origin of Elephants--Variation and Natural Selection distinguished.--Saporta on the Gradation between the Vegetable Forms of the Cretaceous and the Tertiary.--Hypothesis of Derivation more likely to be favored by Botanists than by Zoologists.--Views of Agassiz respecting the Origin, Dispersion, Variation, Characteristics, and Successive Creation of Species contrasted with those of De Candolle and others--Definition of Species--Whether its Essence is in the Likeness or in the Genealogical Connection of the Individuals composing a Species ARTICLE V SEQUOIA AND ITS HISTORY: THE RELATIONS OF NORTH AMERICAN TO NORTHEAST ASIAN AND TO TERTIARY VEGETATION Age and Size of Sequoia.--Isolation.--Decadence.--Related Genera.-- Former Distribution.--Similarity between the Flora of Japan and that of the United States, especially on the Atlantic Side.--Former Glaciation as explaining the Present Dispersion of Species.--This confirmed by the Arctic Fossil Flora of the Tertiary Period.--Tertiary Flora derived from the Preceding Cretaceous.--Order and Adaptation in Organic Nature likened to a Flow.--Order implies an Ordainer ARTICLE VI THE ATTITUDE OF WORKING NATURALISTS TOWARD DARWINISM General Tendency to Acceptance of the Derivative Hypothesis noted.--Lyell, Owen, Alphonse De Candolle, Bentham, Flower, Ailman.-- Dr. Dawson's "Story of the Earth and Man" examined.--Difference between Scientific Men and General Speculators or Amateurs in the Use of Hypotheses ARTICLE VII EVOLUTION AND THEOLOGY Writings of Henslow, Hodges, and Le Conte examined.--Evolution and Design compatible.--The Admission of a System of Nature, with Fixed Laws, concedes in Principle all that the Doctrine of Evolution requires.--Hypotheses, Probabilities, and Surmises, not to be decried by Theologians, who use them, perhaps, more freely and loosely than Naturalists.--Theologians risk too much in the Defense of Untenable Outposts ARTICLE VIII "WHAT IS DARWINISM?" Dr. Hodges Book with this Title criticised.--He declares that Darwinism is Atheism, yet its Founder a Theist.--Darwinism founded, however, upon Orthodox Conceptions, and opposed, not to Theism, but only to Intervention in Nature, while the Key-note of Dr. Hedge's System is Interference.--Views and Writings of St. Clair, Winchell, and Kingsley adverted to ARTICLE IX CHARLES DARWIN: SKETCH ACCOMPANYING A PORTRAIT IN "NATURE" Darwin's Characteristics and Work as a Naturalist compared with those of Robert Brown.--His Illustration of the Principle that "Nature abhors Close Fertilization. "--His Impression upon Natural History exceeded only by Linnaeus.--His Service in restoring Teleology to Natural History ARTICLE X INSECTIVOROUS PLANTS Classification marks Distinctions where Nature exhibits Gradations.-- Recovery of Forgotten Knowledge and History of what was known of Dionzea, Drosera, and Sarracenia. ARTICLE XI INSECTIVOROUS AND CLIMBING PLANTS Review of Darwin's Two Works upon these Subjects--No Absolute Marks for distinguishing between Vegetables and Animals.--New observations upon the Sundews or Droseras.--Their Sensitiveness, Movements, Discernment of the Presence and Appropriation of Animal Matter.--Dionaea, and other Plants of the same Order.--Utricularia and Pinguicula.--Sarracenia and Nepenthes.--Climbing Plants; the Climbing effected through Sensitiveness or Response to External Impression and Automatic Movement.--Capacities inherent in Plants generally, and apparently of no Service to them, developed and utilized by those which climb.--Natural Selection not a Complete Explanation ARTICLE XII DURATION AND ORIGINATION OF RACE AND SPECIES PART I.--Do Varieties in Plants wear out, or tend to wear out?--The Question considered in the Light of Facts, and in that of the Darwinian Theory.--Conclusion that Races sexually propagated need not die of Old Age.--This Conclusion inferred from the Provisions and Arrangements in Nature to secure Cross-Fertilization of Individuals.-- Reference to Mr. Darwin's Development of this View PART II.--Do Species wear out, and, if not, why not?--Implication of the Darwinian Theory that Species are unlimited in Existence.--Examination of an Opposite Doctrine maintained by Naudin.--Evidence that Species may die out from Inherent Causes only indirect and inferential from Arrangements to secure Wide Breeding--Physiological Import of Sexes--Doubtful whether Sexual Reproduction with Wide Breeding is a Preventive or only a Palliative of Decrepitude in Species.-- Darwinian Hypothesis must suppose the Former ARTICLE XIII EVOLUTIONARY TELEOLOGY The Opposition between Morphology and Teleology reconciled by Darwinism, and the Latter reinstated--Character of the New Teleology.--Purpose and Design distinguished--Man has no Monopoly of the Latter.--Inference of Design from Adaptation and Utility legitimate; also in Hume's Opinion irresistible--The Principle of Design, taken with Specific Creation, totally insufficient and largely inapplicable; but, taken with the Doctrine of the Evolution of Species in Nature, applicable, pertinent, and, moreover, necessary.--Illustrations from Abortive Organs, supposed Waste of Being, etc.--All Nature being of a Piece, Design must either pervade or be absent from the Whole.--Its Absence not to be inferred because the Events take place in Nature--Illustration of the Nature and Province of Natural Selection.--It picks out, but does not originate Variations; these not a Product of, but a Response to, the Environment; not physical, but physiological--Adaptations in Nature not explained by Natural Selection apart from Design or Final Cause--Absurdity of associating Design only with Miracle--What is meant by Nature.--The Tradition of the DIVINE in Nature, testified to by Aristotle, comes down to our Day with Undiminished Value PREFACE These papers are now collected at the request of friends and correspondents, who think that they may be useful; and two new essays are added. Most of the articles were written as occasion called for them within the past sixteen years, and contributed to various periodicals, with little thought of their forming a series, and none of ever bringing them together into a volume, although one of them (the third) was once reprinted in a pamphlet form. It is, therefore, inevitable that there should be considerable iteration in the argument, if not in the language. This could not be eliminated except by recasting the whole, which was neither practicable nor really desirable. It is better that they should record, as they do, the writer's freely-expressed thoughts upon the subject at the time; and to many readers there may be some advantage in going more than once, in different directions, over the same ground. If these essays were to be written now, some things might be differently expressed or qualified, but probably not so as to affect materially any important point. Accordingly, they are here reprinted unchanged, except by a few merely verbal alterations made in proof-reading, and the striking out of one or two superfluous or immaterial passages. A very few additional notes or references are appended. To the last article but one a second part is now added, and the more elaborate Article XIII is wholly new. If it be objected that some of these pages are written in a lightness of vein not quite congruous with the gravity of the subject and the seriousness of its issues, the excuse must be that they were written with perfect freedom, most of them as anonymous contributions to popular journals, and that an argument may not be the less sound or an exposition less effective for being playful. Some of the essays, however, dealing with points of speculative scientific interest, may redress the balance, and be thought sufficiently heavy if not solid. To the objection likely to be made, that they cover only a part of the ground, it can only be replied that they do not pretend to be systematic or complete. They are all essays relating in some way or other to the subject which has been, during these years, of paramount interest to naturalists, and not much less so to most thinking people. The first appeared between sixteen and seventeen years ago, immediately after the publication of Darwin's "Origin of Species by Means of Natural Selection," as a review of that volume, which, it was then foreseen, was to initiate a revolution in general scientific opinion. Long before our last article was written, it could be affirmed that the general doctrine of the derivation of species (to put it comprehensively) has prevailed over that of specific creation, at least to the extent of being the received and presumably in some sense true conception. Far from undertaking any general discussion of evolution, several even of Mr. Darwin's writings have not been noticed, and topics which have been much discussed elsewhere are not here adverted to. This applies especially to what may be called deductive evolution--a subject which lay beyond the writer's immediate scope, and to which neither the bent of his mind nor the line of his studies has fitted him to do justice. If these papers are useful at all, it will be as showing how these new views of our day are regarded by a practical naturalist, versed in one department only (viz., Botany), most interested in their bearings upon its special problems, one accustomed to direct and close dealings with the facts in hand, and disposed to rise from them only to the consideration of those general questions upon which they throw or from which they receive illustration. Then as to the natural theological questions which (owing to circumstances needless now to be recalled or explained) are here throughout brought into what most naturalists, and some other readers, may deem undue prominence, there are many who may be interested to know how these increasingly prevalent views and their tendencies are regarded by one who is scientifically, and in his own fashion, a Darwinian, philosophically a convinced theist, and religiously an acceptor of the "creed commonly called the Nicene," as the exponent of the Christian faith. "Truth emerges sooner from error than from confusion," says Bacon; and clearer views than commonly prevail upon the points at issue regarding "religion and science" are still sufficiently needed to justify these endeavors. BOTANIC GARDEN, CAMBRIDGE, MASS., June, 1876. ______________________________________ I THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION [I-1] (American Journal of Science and Arts, March, 1860) This book is already exciting much attention. Two American editions are announced, through which it will become familiar to many of our readers, before these pages are issued. An abstract of the argument--for "the whole volume is one long argument," as the author states--is unnecessary in such a case; and it would be difficult to give by detached extracts. For the volume itself is an abstract, a prodromus of a detailed work upon which the author has been laboring for twenty years, and which "will take two or three more years to complete." It is exceedingly compact; and although useful summaries are appended to the several chapters, and a general recapitulation contains the essence of the whole, yet much of the aroma escapes in the treble distillation, or is so concentrated that the flavor is lost to the general or even to the scientific reader. The volume itself--the proof-spirit--is just condensed enough for its purpose. It will be far more widely read, and perhaps will make deeper impression, than the elaborate work might have done, with all its full details of the facts upon which the author's sweeping conclusions have been grounded. At least it is a more readable book: but all the facts that can be mustered in favor of the theory are still likely to be needed. Who, upon a single perusal, shall pass judgment upon a work like this, to which twenty of the best years of the life of a most able naturalist have been devoted? And who among those naturalists who hold a position that entitles them to pronounce summarily upon the subject, can be expected to divest himself for the nonce of the influence of received and favorite systems? In fact, the controversy now opened is not likely to be settled in an off-hand way, nor is it desirable that it should be. A spirited conflict among opinions of every grade must ensue, which--to borrow an illustration from the doctrine of the book before us--may be likened to the conflict in Nature among races in the struggle for life, which Mr. Darwin describes; through which the views most favored by facts will be developed and tested by "Natural Selection," the weaker ones be destroyed in the process, and the strongest in the long-run alone survive. The duty of reviewing this volume in the American Journal of Science would naturally devolve upon the principal editor,' whose wide observation and profound knowledge of various departments of natural history, as well as of geology, particularly qualify him for the task. But he has been obliged to lay aside his pen, and to seek in distant lands the entire repose from scientific labor so essential to the restoration of his health--a consummation devoutly to be wished, and confidently to be expected. Interested as Mr. Dana would be in this volume, he could not be expected to accept this doctrine. Views so idealistic as those upon which his "Thoughts upon Species" [I-2] are grounded, will not harmonize readily with a doctrine so thoroughly naturalistic as that of Mr. Darwin. Though it is just possible that one who regards the kinds of elementary matter, such as oxygen and hydrogen, and the definite compounds of these elementary matters, and their compounds again, in the mineral kingdom, as constituting species, in the same sense, fundamentally, as that of animal and vegetable species, might admit an evolution of one species from another in the latter as well as the former case. Between the doctrines of this volume and those of the other great naturalist whose name adorns the title-page of this journal, the widest divergence appears. It is interesting to contrast the two, and, indeed, is necessary to our purpose; for this contrast brings out most prominently, and sets in strongest light and shade, the main features of the theory of the origination of species by means of Natural Selection. The ordinary and generally-received view assumes the independent, specific creation of each kind of plant and animal in a primitive stock, which reproduces its like from generation to generation, and so continues the species. Taking the idea of species from this perennial succession of essentially similar individuals, the chain is logically traceable back to a local origin in a single stock, a single pair, or a single individual, from which all the individuals composing the species have proceeded by natural generation. Although the similarity of progeny to parent is fundamental in the conception of species, yet the likeness is by no means absolute; all species vary more or less, and some vary remarkably--partly from the influence of altered circumstances, and partly (and more really) from unknown constitutional causes which altered conditions favor rather than originate. But these variations are supposed to be mere oscillations from a normal state, and in Nature to be limited if not transitory; so that the primordial differences between species and species at their beginning have not been effaced, nor largely obscured, by blending through variation. Consequently, whenever two reputed species are found to blend in Nature through a series of intermediate forms, community of origin is inferred, and all the forms, however diverse, are held to belong to one species. Moreover, since bisexuality is the rule in Nature (which is practically carried out, in the long-run, far more generally than has been suspected), and the heritable qualities of two distinct individuals are mingled in the offspring, it is supposed that the general sterility of hybrid progeny interposes an effectual barrier against the blending of the original species by crossing. From this generally-accepted view the well-known theory of Agassiz and the recent one of Darwin diverge in exactly opposite directions. That of Agassiz differs fundamentally from the ordinary view only in this, that it discards the idea of a common descent as the real bond of union among the individuals of a species, and also the idea of a local origin--supposing, instead, that each species originated simultaneously, generally speaking, over the whole geographical area it now occupies or has occupied, and in perhaps as many individuals as it numbered at any subsequent period. Mr. Darwin, on the other hand, holds the orthodox view of the descent of all the individuals of a species not only from a local birthplace, but from a single ancestor or pair; and that each species has extended and established itself, through natural agencies, wherever it could; so that the actual geographical distribution of any species is by no means a primordial arrangement, but a natural result. He goes farther, and this volume is a protracted argument intended to prove that the species we recognize have not been independently created, as such, but have descended, like varieties, from other species. Varieties, on this view, are incipient or possible species: species are varieties of a larger growth and a wider and earlier divergence from the parent stock; the difference is one of degree, not of kind. The ordinary view--rendering unto Caesar the things that are Caesar's--looks to natural agencies for the actual distribution and perpetuation of species, to a supernatural for their origin. The theory of Agassiz regards the origin of species and their present general distribution over the world as equally primordial, equally supernatural; that of Darwin, as equally derivative, equally natural. The theory of Agassiz, referring as it does the phenomena both of origin and distribution directly to the Divine will--thus removing the latter with the former out of the domain of inductive science (in which efficient cause is not the first, but the last word)--may be said to be theistic to excess. The contrasted theory is not open to this objection. Studying the facts and phenomena in reference to proximate causes, and endeavoring to trace back the series of cause and effect as far as possible, Darwin's aim and processes are strictly scientific, and his endeavor, whether successful or futile, must be regarded as a legitimate attempt to extend the domain of natural or physical science. For, though it well may be that "organic forms have no physical or secondary cause," yet this can be proved only indirectly, by the failure of every attempt to refer the phenomena in question to causal laws. But, however originated, and whatever be thought of Mr. Darwin's arduous undertaking in this respect, it is certain that plants and animals are subject from their birth to physical influences, to which they have to accommodate themselves as they can. How literally they are "born to trouble," and how incessant and severe the struggle for life generally is, the present volume graphically describes. Few will deny that such influences must have gravely affected the range and the association of individuals and species on the earth's surface. Mr. Darwin thinks that, acting upon an inherent predisposition to vary, they have sufficed even to modify the species themselves and produce the present diversity. Mr. Agassiz believes that they have not even affected the geographical range and the actual association of species, still less their forms; but that every adaptation of species to climate, and of species to species, is as aboriginal, and therefore as inexplicable, as are the organic forms themselves. Who shall decide between such extreme views so ably maintained on either hand, and say how much of truth there may be in each? The present reviewer has not the presumption to undertake such a task. Having no prepossession in favor of naturalistic theories, but struck with the eminent ability of Mr. Darwin's work, and charmed with its fairness, our humbler duty will be performed if, laying aside prejudice as much as we can, we shall succeed in giving a fair account of its method and argument, offering by the way a few suggestions, such as might occur to any naturalist of an inquiring mind. An editorial character for this article must in justice be disclaimed. The plural pronoun is employed not to give editorial weight, but to avoid even the appearance of egotism, and also the circumlocution which attends a rigorous adherence to the impersonal style. We have contrasted these two extremely divergent theories, in their broad statements. It must not be inferred that they have no points nor ultimate results in common. In the first place, they practically agree in upsetting, each in its own way, the generally-received definition of species, and in sweeping away the ground of their objective existence in Nature. The orthodox conception of species is that of lineal descent: all the descendants of a common parent, and no other, constitute a species; they have a certain identity because of their descent, by which they are supposed to be recognizable. So naturalists had a distinct idea of what they meant by the term species, and a practical rule, which was hardly the less useful because difficult to apply in many cases, and because its application was indirect: that is, the community of origin had to be inferred from the likeness; such degree of similarity, and such only, being held to be con-specific as could be shown or reasonably inferred to be compatible with a common origin. And the usual concurrence of the whole body of naturalists (having the same data before them) as to what forms are species attests the value of the rule, and also indicates some real foundation for it in Nature. But if species were created in numberless individuals over broad spaces of territory, these individuals are connected only in idea, and species differ from varieties on the one hand, and from genera, tribes, etc., on the other, only in degree; and no obvious natural reason remains for fixing upon this or that degree as specific, at least no natural standard, by which the opinions of different naturalists may be correlated. Species upon this view are enduring, but subjective and ideal. Any three or more of the human races, for example, are species or not species, according to the bent of the naturalist's mind. Darwin's theory brings us the other way to the same result. In his view, not only all the individuals of a species are descendants of a common parent, but of all the related species also. Affinity, relationship, all the terms which naturalists use figuratively to express an underived, unexplained resemblance among species, have a literal meaning upon Darwin's system, which they little suspected, namely, that of inheritance. Varieties are the latest offshoots of the genealogical tree in "an unlineal" order; species, those of an earlier date, but of no definite distinction; genera, more ancient species, and so on. The human races, upon this view, likewise may or may not be species according to the notions of each naturalist as to what differences are specific; but, if not species already, those races that last long enough are sure to become so. It is only a question of time. How well the simile of a genealogical tree illustrates the main ideas of Darwin's theory the following extract from the summary of the fourth chapter shows: "It is a truly wonderful fact--the wonder of which we are apt to overlook from familiarity--that all animals and all plants throughout all time and space should be related to each other in group subordinate to group, in the manner which we everywhere behold--namely, varieties of the same species most closely related together, species of the same genus less closely and unequally related together, forming sections and sub-genera, species of distinct genera much less closely related, and genera related in different degrees, forming sub-families, families, orders, sub-classes, and classes. The several subordinate groups in any class cannot be ranked in a single file, but seem rather to be clustered round points, and these round other points, and so on in almost endless cycles. On the view that each species has been independently created, I can see no explanation of this great fact in the classification of all organic beings; but, to the best of my judgment, it is explained through inheritance and the complex action of natural selection, entailing extinction and divergence of character, as we have seen illustrated in the diagram. "The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species. At each period of growth all the growing twigs have tried to branch out on all sides, and overtop and kill the surrounding twigs and branches, in the same manner as species and groups of species have tried to overmaster other species in the great battle for life. The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was small, budding twigs; and this connection of the former and present buds by ramifying branches may well represent the classification of all extinct and living species in groups subordinate to groups. Of the many twigs which flourished when the tree was a mere bush, only two or three, now grown into great branches, yet survive and bear all the other branches; so with the species which lived during long-past geological periods, very few now have living and modified descendants. From the first growth of the tree, many a limb and branch has decayed and dropped off; and these lost branches of various sizes may represent those whole orders, families, and genera, which have now no living representatives, and which are known to us only from having been found in a fossil state. As we here and there see a thin, straggling branch springing from a fork low down in a tree, and which by some chance has been favored and is still alive on its summit, so we occasionally see an animal like the Ornithorhynchus or Lepidosiren, which in some small degree connects by its affinities two large branches of life, and which has apparently been saved from fatal competition by having inhabited a protected station. As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever-branching and beautiful ramification." It may also be noted that there is a significant correspondence between the rival theories as to the main facts employed. Apparently every capital fact in the one view is a capital fact in the other. The difference is in the interpretation. To run the parallel ready made to our hands: [I-4] "The simultaneous existence of the most diversified types under identical circumstances . . . the repetition of similar types under the most diversified circumstances . . . the unity of plan in otherwise highly-diversified types of animals . . . the correspondence, now generally known as special homologies, in the details of structure otherwise entirely disconnected, down to the most minute peculiarities . . . the various degrees and different kinds of relationship among animals which (apparently) can have no genealogical connection . . . the simultaneous existence in the earliest geological periods, . . . of representatives of all the great types of the animal kingdom . . . the gradation based upon complications of structure which may be traced among animals built upon the same plan; the distribution of some types over the most extensive range of surface of the globe, while others are limited to particular geographical areas . . . the identity of structures of these types, notwithstanding their wide geographical distribution . . . the community of structure in certain respects of animals otherwise entirely different, but living within the same geographical area . . . the connection by series of special structures observed in animals widely scattered over the surface of the globe . . . the definite relations in which animals stand to the surrounding world, . . . the relations in which individuals of the same species stand to one another . . . the limitation of the range of changes which animals undergo during their growth . . . the return to a definite norm of animals which multiply in various ways . . . the order of succession of the different types of animals and plants characteristic of the different geological epochs, . . . the localization of some types of animals upon the same points of the surface of the globe during several successive geological periods . . . the parallelism between the order of succession of animals and plants in geological times, and the gradation among their living representatives . . . the parallelism between the order of succession of animals in geological times and the changes their living representatives undergo during their embryological growth, [I-5] . . . the combination in many extinct types of characters which in later ages appear disconnected in different types, . . . the parallelism between the gradation among animals and the changes they undergo during their growth, . . . the relations existing between these different series and the geographical distribution of animals, . . . the connection of all the known features of Nature into one system--" In a word, the whole relations of animals, etc., to surrounding Nature and to each other, are regarded under the one view as ultimate facts, or in the ultimate aspect, and interpreted theologically; under the other as complex facts, to be analyzed and interpreted scientifically. The one naturalist, perhaps too largely assuming the scientifically unexplained to be inexplicable, views the phenomena only in their supposed relation to the Divine mind. The other, naturally expecting many of these phenomena to be resolvable under investigation, views them in their relations to one another, and endeavors to explain them as far as he can (and perhaps farther) through natural causes. But does the one really exclude the other? Does the investigation of physical causes stand opposed to the theological view and the study of the harmonies between mind and Nature? More than this, is it not most presumable that an intellectual conception realized in Nature would be realized through natural agencies? Mr. Agassiz answers these questions affirmatively when he declares that "the task of science is to investigate what has been done, to inquire if possible how it has been done, rather than to ask what is possible for the Deity, since we can know that only by what actually exists;" and also when he extends the argument for the intervention in Nature of a creative mind to its legitimate application in the inorganic world; which, he remarks, "considered in the same light, would not fail also to exhibit unexpected evidence of thought, in the character of the laws regulating the chemical combinations, the action of physical forces, etc., etc." [I-6] Mr. Agassiz, however, pronounces that "the connection between the facts is only intellectual"--an opinion which the analogy of the inorganic world, just referred to, does not confirm, for there a material connection between the facts is justly held to be consistent with an intellectual--and which the most analogous cases we can think of in the organic world do not favor; for there is a material connection between the grub, the pupa, and the butterfly, between the tadpole and the frog, or, still better, between those distinct animals which succeed each other in alternate and very dissimilar generations. So that mere analogy might rather suggest a natural connection than the contrary; and the contrary cannot be demonstrated until the possibilities of Nature under the Deity are fathomed. But, the intellectual connection being undoubted, Mr. Agassiz properly refers the whole to "the agency of Intellect as its first cause." In doing so, however, he is not supposed to be offering a scientific explanation of the phenomena. Evidently he is considering only the ultimate why, not the proximate why or how. Now the latter is just what Mr. Darwin is considering. He conceives of a physical connection between allied species; but we suppose he does not deny their intellectual connection, as related to a supreme intelligence. Certainly we see no reason why he should, and many reasons why he should not, Indeed, as we contemplate the actual direction of investigation and speculation in the physical and natural sciences, we dimly apprehend a probable synthesis of these divergent theories, and in it the ground for a strong stand against mere naturalism. Even if the doctrine of the origin of species through natural selection should prevail in our day, we shall not despair; being confident that the genius of an Agassiz will be found equal to the work of constructing, upon the mental and material foundations combined, a theory of Nature as theistic and as scientific as that which he has so eloquently expounded. To conceive the possibility of "the descent of species from species by insensibly fine gradations" during a long course of time, and to demonstrate its compatibility with a strictly theistic view of the universe, is one thing; to substantiate the theory itself or show its likelihood is quite another thing. This brings us to consider what Darwin's theory actually is, and how he supports it. That the existing kinds of animals and plants, or many of them, may be derived from other and earlier kinds, in the lapse of time, is by no means a novel proposition. Not to speak of ancient speculations of the sort, it is the well-known Lamarckian theory. The first difficulty which such theories meet with is that in the present age, with all its own and its inherited prejudgments, the whole burden of proof is naturally, and indeed properly, laid upon the shoulders of the propounders; and thus far the burden has been more than they could bear. From the very nature of the case, substantive proof of specific creation is not attainable; but that of derivation or transmutation of species may be. He who affirms the latter view is bound to do one or both of two things: 1. Either to assign real and adequate causes, the natural or necessary result of which must be to produce the present diversity of species and their actual relations; or, 2. To show the general conformity of the whole body of facts to such assumption, and also to adduce instances explicable by it and inexplicable by the received view, so perhaps winning our assent to the doctrine, through its competency to harmonize all the facts, even though the cause of the assumed variation remain as occult as that of the transformation of tadpoles into frogs, or that of Coryne into Sarzia. The first line of proof, successfully carried out, would establish derivation as a true physical theory; the second, as a sufficient hypothesis. Lamarck mainly undertook the first line, in a theory which has been so assailed by ridicule that it rarely receives the credit for ability to which in its day it was entitled, But he assigned partly unreal, partly insufficient causes; and the attempt to account for a progressive change in species through the direct influence of physical agencies, and through the appetencies and habits of animals reacting upon their structure, thus causing the production and the successive modification of organs, is a conceded and total failure. The shadowy author of the "Vestiges of the Natural History of Creation" can hardly be said to have undertaken either line, in a scientific way. He would explain the whole progressive evolution of Nature by virtue of an inherent tendency to development, thus giving us an idea or a word in place of a natural cause, a restatement of the proposition instead of an explanation. Mr. Darwin attempts both lines of proof, and in a strictly scientific spirit; but the stress falls mainly upon the first, for, as he does assign real causes, he is bound to prove their adequacy. It should be kept in mind that, while all direct proof of independent origination is attainable from the nature of the case, the overthrow of particular schemes of derivation has not established the opposite proposition. The futility of each hypothesis thus far proposed to account for derivation may be made apparent, or unanswerable objections may be urged against it; and each victory of the kind may render derivation more improbable, and therefore specific creation more probable, without settling the question either way. New facts, or new arguments and a new mode of viewing the question, may some day change the whole aspect of the case. It is with the latter that Mr. Darwin now reopens the discussion. Having conceived the idea that varieties are incipient species, he is led to study variation in the field where it shows itself most strikingly, and affords the greatest facilities to investigation. Thoughtful naturalists have had increasing grounds to suspect that a reexamination of the question of species in zoology and botany, commencing with those races which man knows most about, viz., the domesticated and cultivated races, would be likely somewhat to modify the received idea of the entire fixity of species. This field, rich with various but unsystematized stores of knowledge accumulated by cultivators and breeders, has been generally neglected by naturalists, because these races are not in a state of nature; whereas they deserve particular attention on this very account, as experiments, or the materials for experiments, ready to our hand. In domestication we vary some of the natural conditions of a species, and thus learn experimentally what changes are within the reach of varying conditions in Nature. We separate and protect a favorite race against its foes or its competitors, and thus learn what it might become if Nature ever afforded it equal opportunities. Even when, to subserve human uses, we modify a domesticated race to the detriment of its native vigor, or to the extent of practical monstrosity, although we secure forms which would not be originated and could not be perpetuated in free Nature, yet we attain wider and juster views of the possible degree of variation. We perceive that some species are more variable than others, but that no species subjected to the experiment persistently refuses to vary; and that, when it has once begun to vary, its varieties are not the less but the more subject to variation. "No case is on record of a variable being ceasing to be variable under cultivation." It is fair to conclude, from the observation of plants and animals in a wild as well as domesticated state, that the tendency to vary is general, and even universal. Mr. Darwin does "not believe that variability is an inherent and necessary contingency, under all circumstances, with all organic beings, as some authors have thought." No one supposes variation could occur under all circumstances; but the facts on the whole imply a universal tendency, ready to be manifested under favorable circumstances. In reply to the assumption that man has chosen for domestication animals and plants having an extraordinary inherent tendency to vary, and likewise to withstand diverse climates, it is asked: "How could a savage possibly know, when he first tamed an animal, whether it would vary in succeeding generations and whether it would endure other climates? Has the little variability of the ass or Guinea-fowl, or the small power of endurance of warmth by the reindeer, or of cold by the common camel, prevented their domestication? I cannot doubt that if other animals and plants, equal in number to our domesticated productions, and belonging to equally diverse classes and countries, were taken from a state of nature, and could be made to breed for an equal number of generations under domestication, they would vary on an average as largely as the parent species of our existing domesticated productions have varied." As to amount of variation, there is the common remark of naturalists that the varieties of domesticated plants or animals often differ more widely than do the individuals of distinct species in a wild state: and even in Nature the individuals of some species are known to vary to a degree sensibly wider than that which separates related species. In his instructive section on the breeds of the domestic pigeon, our author remarks that "at least a score of pigeons might be chosen which if shown to an ornithologist, and he were told that they were wild birds, would certainly be ranked by him as well-defined species. Moreover, I do not believe that any ornithologist would place the English carrier, the short-faced tumbler, the runt, the barb, pouter, and fantail, in the same genus; more especially as in each of these breeds several truly-inherited sub-breeds, or species, as he might have called them, could be shown him." That this is not a case like that of dogs, in which probably the blood of more than one species is mingled, Mr. Darwin proceeds to show, adducing cogent reasons for the common opinion that all have descended from the wild rock-pigeon. Then follow some suggestive remarks: "I have discussed the probable origin of domestic pigeons at some, yet quite insufficient, length; because when I first kept pigeons and watched the several kinds, knowing well how true they bred, I felt fully as much difficulty in believing that they could ever have descended from a common parent as any naturalist could in coming to a similar conclusion in regard to many species of finches, or other large groups of birds, in Nature. One circumstance has struck me much; namely, that all the breeders of the various domestic animals and the cultivators of plants, with whom I have ever conversed, or whose treatises I have read, are firmly convinced that the several breeds to which each has attended are descended from so many aboriginally distinct species. Ask, as I have asked, a celebrated raiser of Hereford cattle, whether his cattle might not have descended from long-horns, and he will laugh you to scorn. I have never met a pigeon, or poultry, or duck, or rabbit fancier, who was not fully convinced that each main breed was descended from a distinct species. Van Mons, in his treatise on pears and apples, shows how utterly he disbelieves that the several sorts, for instance a Ribston-pippin or Codlin-apple, could ever have proceeded from the seeds of the same tree. Innumerable other examples could be given. The explanation, I think, is simple: from long-continued study they arc strongly impressed with the differences between the several races; and though they well know that each race varies slightly, for they win their prizes by selecting such slight differences, yet they ignore all general arguments, and refuse to sum up in their minds slight differences accumulated during many successive generations. May not those naturalists who, knowing far less of the laws of inheritance than does the breeder, and knowing no more than he does of the intermediate links in the long lines of descent, yet admit that many of our domestic races have descended from the same parents--may they not learn a lesson of caution, when they deride the idea of species in a state of nature being lineal descendants of other species?" The actual causes of variation are unknown. Mr. Darwin favors the opinion of the late Mr. Knight, the great philosopher of horticulture, that variability tinder domestication is somehow connected with excess of food. He regards the unknown cause as acting chiefly upon the reproductive system of the parents, which system, judging from the effect of confinement or cultivation upon its functions, he concludes to be more susceptible than any other to the action of changed conditions of life. The tendency to vary certainly appears to be much stronger under domestication than in free Nature. But we are not sure that the greater variableness of cultivated races is not mainly owing to the far greater opportunities for manifestation and accumulation--a view seemingly all the more favorable to Mr. Darwin's theory. The actual amount of certain changes, such as size or abundance of fruit, size of udder, stands of course in obvious relation to supply of food. Really, we no more know the reason why the progeny occasionally deviates from the parent than we do why it usually resembles it. Though the laws and conditions governing variation are known to a certain extent, those governing inheritance are apparently inscrutable. "Perhaps," Darwin remarks, "the correct way of viewing the whole subject would be, to look at the inheritance of every character whatever as the rule, and non-inheritance as the anomaly." This, from general and obvious considerations, we have long been accustomed to do. Now, as exceptional instances are expected to be capable of explanation, while ultimate laws are not, it is quite possible that variation may be accounted for, while the great primary law of inheritance remains a mysterious fact. The common proposition is, that species reproduce their like; this is a sort of general inference, only a degree closer to fact than the statement that genera reproduce their like. The true proposition, the fact incapable of further analysis, is, that individuals reproduce their like--that characteristics are inheritable. So varieties, or deviations, once originated, are perpetuable, like species. Not so likely to be perpetuated, at the outset; for the new form tends to resemble a grandparent and a long line of similar ancestors, as well as to resemble its immediate progenitors. Two forces which coincide in the ordinary case, where the offspring resembles its parent, act in different directions when it does not and it is uncertain which will prevail. If the remoter but very potent ancestral influence predominates, the variation disappears with the life of the individual. If that of the immediate parent--feebler no doubt, but closer--the variety survives in the offspring; whose progeny now has a redoubled tendency to produce its own like; whose progeny again is almost sure to produce its like, since it is much the same whether it takes after its mother or its grandmother. In this way races arise, which under favorable conditions may be as hereditary as species. In following these indications, watching opportunities, and breeding only from those individuals which vary most in a desirable direction, man leads the course of variation as he leads a streamlet--apparently at will, but never against the force of gravitation--to a long distance from its source, and makes it more subservient to his use or fancy. He unconsciously strengthens those variations which he prizes when he plants the seed of a favorite fruit, preserves a favorite domestic animal, drowns the uglier kittens of a litter, and allows only the handsomest or the best mousers to propagate. Still more, by methodical selection, in recent times almost marvelous results have been produced in new breeds of cattle, sheep, and poultry, and new varieties of fruit of greater and greater size or excellence. It is said that all domestic varieties, if left to run wild, would revert to their aboriginal stocks. Probably they would wherever various races of one species were left to commingle. At least the abnormal or exaggerated characteristics induced by high feeding, or high cultivation and prolonged close breeding, would promptly disappear; and the surviving stock would soon blend into a homogeneous result (in a way presently explained), which would naturally be taken for the original form; but we could seldom know if it were so. It is by no means certain that the result would be the same if the races ran wild each in a separate region. Dr. Hooker doubts if there is a true reversion in the case of plants. Mr. Darwin's observations rather favor it in the animal kingdom. With mingled races reversion seems well made out in the case of pigeons. The common opinion upon this subject therefore probably has some foundation, But even if we regard varieties as oscillations around a primitive centre or type, still it appears from the readiness with which such varieties originate that a certain amount of disturbance would carry them beyond the influence of the primordial attraction, where they may become new centres of variation. Some suppose that races cannot be perpetuated indefinitely even by keeping up the conditions under which they were fixed; but the high antiquity of several, and the actual fixity of many of them, negative this assumption. "To assert that we could not breed our cart and race horses, long and short horned cattle, and poultry of various breeds, for almost an infinite number of generations, would be opposed to all experience." Why varieties develop so readily and deviate so widely under domestication, while they are apparently so rare or so transient in free Nature, may easily be shown. In Nature, even with hermaphrodite plants, there is a vast amount of cross-fertilization among various individuals of the same species. The inevitable result of this (as was long ago explained in this Journal [I-7]) is to repress variation, to keep the mass of a species comparatively homogeneous over any area in which it abounds in individuals. Starting from a suggestion of the late Mr. Knight, now so familiar, that close interbreeding diminishes vigor and fertility; [I-8] and perceiving that bisexuality is ever aimed at in Nature--being attained physiologically in numerous cases where it is not structurally--Mr. Darwin has worked out the subject in detail, and shown how general is the concurrence, either habitual or occasional, of two hermaphrodite individuals in the reproduction of their kind; and has drawn the philosophical inference that probably no organic being self-fertilizes indefinitely; but that a cross with another individual is occasionally--perhaps at very long intervals--indispensable. We refer the reader to the section on the intercrossing of individuals (pp. 96--101), and also to an article in the Gardeners' Chronicle a year and a half ago, for the details of a very interesting contribution to science, irrespective of theory. In domestication, this intercrossing may be prevented; and in this prevention lies the art of producing varieties. But "the art itself is Nature," since the whole art consists in allowing the most universal of all natural tendencies in organic things (inheritance) to operate uncontrolled by other and obviously incidental tendencies. No new power, no artificial force, is brought into play either by separating the stock of a desirable variety so as to prevent mixture, or by selecting for breeders those individuals which most largely partake of the peculiarities for which the breed is valued. {I-9] We see everywhere around us the remarkable results which Nature may be said to have brought about under artificial selection and separation. Could she accomplish similar results when left to herself? Variations might begin, we know they do begin, in a wild state. But would any of them be preserved and carried to an equal degree of deviation? Is there anything in Nature which in the long-run may answer to artificial selection? Mr. Darwin thinks that there is; and Natural Selection is the key-note of his discourse, As a preliminary, he has a short chapter to show that there is variation in Nature, and therefore something for natural selection to act upon. He readily shows that such mere variations as may be directly referred to physical conditions (like the depauperation of plants in a sterile soil, or their dwarfing as they approach an Alpine summit, the thicker fur of an animal from far northward, etc.), and also those individual differences which we everywhere recognize but do not pretend to account for, are not separable by any assignable line from more strongly-marked varieties; likewise that there is no clear demarkation between the latter and sub-species, or varieties of the highest grade (distinguished from species not by any known inconstancy, but by the supposed lower importance of their characteristics); nor between these and recognized species. "These differences blend into each other in an insensible series, and the series impresses the mind with an idea of an actual passage." This gradation from species downward is well made out. To carry it one step farther upward, our author presents in a strong light the differences which prevail among naturalists as to what forms should be admitted to the rank of species. Some genera (and these in some countries) give rise to far more discrepancy than others; and it is concluded that the large or dominant genera are usually the most variable. In a flora so small as the British, 182 plants, generally reckoned as varieties, have been ranked by some botanists as species. Selecting the British genera which include the most polymorphous forms, it appears that Babington's Flora gives them 251 species, Bentham's only 112, a difference of 139 doubtful forms. These are nearly the extreme views, but they are the views of two most capable and most experienced judges, in respect to one of the best-known floras of the world. The fact is suggestive, that the best-known countries furnish the greatest number of such doubtful cases. Illustrations of this kind may be multiplied to a great extent. They make it plain that, whether species in Nature are aboriginal and definite or not, our practical conclusions about them, as embodied in systematic works, are not facts but judgments, and largely fallible judgments- How much of the actual coincidence of authorities is owing to imperfect or restricted observation, and to one naturalist's adopting the conclusions of another without independent observation, this is not the place to consider. It is our impression that species of animals are more definitely marked than those of plants; this may arise from our somewhat extended acquaintance with the latter, and our ignorance of the former. But we are constrained by our experience to admit the strong likelihood, in botany, that varieties on the one hand, and what are called closely-related species on the other, do not differ except in degree. Whenever this wider difference separating the latter can be spanned by intermediate forms, as it sometimes is, no botanist long resists the inevitable conclusion. Whenever, therefore, this wider difference can be shown to be compatible with community of origin, and explained through natural selection or in any other way, we are ready to adopt the probable conclusion; and we see beforehand how strikingly the actual geographical association of related species favors the broader view. Whether we should continue to regard the forms in question as distinct species, depends upon what meaning we shall finally attach to that term; and that depends upon how far the doctrine of derivation can be carried back and how well it can be supported. In applying his principle of natural selection to the work in hand, Mr. Darwin assumes, as we have seen: i. Some variability of animals and plants in nature; 2. The absence of any definite distinction between slight variations, and varieties of the highest grade; 3. The fact that naturalists do not practically agree, and do not increasingly tend to agree, as to what forms are species and what are strong varieties, thus rendering it probable that there may be no essential and original difference, or no possibility of ascertaining it, at least in many cases; also, 4. That the most flourishing and dominant species of the larger genera on an average vary most (a proposition which can be substantiated only by extensive comparisons, the details of which are not given); and, 5. That in large genera the species are apt to be closely but unequally allied together, forming little clusters round certain species--just such clusters as would be formed if we suppose their members once to have been satellites or varieties of a central or parent species, but to have attained at length a wider divergence and a specific character. The fact of such association is undeniable; and the use which Mr. Darwin makes of it seems fair and natural. The gist of Mr. Darwin's work is to show that such varieties are gradually diverged into species and genera through natural selection; that natural selection is the inevitable result of the struggle for existence which all living things are engaged in; and that this struggle is an unavoidable consequence of several natural causes, but mainly of the high rate at which all organic beings tend to increase. Curiously enough, Mr. Darwin's theory is grounded upon the doctrine of Malthus and the doctrine of Hobbes. The elder DeCandolle had conceived the idea of the struggle for existence, and, in a passage which would have delighted the cynical philosopher of Malmesbury, had declared that all Nature is at war, one organism with another or with external Nature; and Lyell and Herbert had made considerable use of it. But Hobbes in his theory of society, and Darwin in his theory of natural history, alone have built their systems upon it. However moralists and political economists may regard these doctrines in their original application to human society and the relation of population to subsistence, their thorough applicability to the great society of the organic world in general is now undeniable. And to Mr. Darwin belongs the credit of making this extended application, and of working out the immensely diversified results with rare sagacity and untiring patience. He has brought to view real causes which have been largely operative in the establishment of the actual association and geographical distribution of plants and animals. In this he must be allowed to have made a very important contribution to an interesting department of science, even if his theory fails in the endeavor to explain the origin or diversity of species. "Nothing is easier," says our author, "than to admit in words the truth of the universal struggle for life, or more difficult--at least I have found it so--than constantly to bear this conclusion in mind. Yet, unless it be thoroughly ingrained in the mind, I am convinced that the whole economy of Nature, with every fact on distribution, rarity, abundance, extinction, and variation, will be dimly seen or quite misunderstood. We behold the face of Nature bright with gladness, we often see superabundance of food; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind that, though food may be now superabundant, it is not so at all seasons of each recurring year."--(p. 62.) "There is no exception to the rule that every organic being naturally increases at so high a rate that, if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in a few thousand years, there would literally not be standing-room for his progeny. Linnaeus has calculated that if an annual plant produced only two seeds--and there is no plant so unproductive as this--and their seedlings next year produced two, and so on, then in twenty years there would be a million plants. The elephant is reckoned to be the slowest breeder of all known animals, and I have taken some pains to estimate its pro!)able minimum rate of natural increase; it will be under the mark to assume that it breeds when thirty years old, and goes on breeding till ninety years old, bringing forth three pairs of young in this interval; if this be so, at the end of the fifth century there would be alive fifteen million elephants, descended from the first pair. "But we have better evidence on this subject than mere theoretical calculations, namely, the numerous recorded cases of the astonishingly rapid increase of various animals in a state of nature, when circumstances have been favorable to them during two or three following seasons. Still more striking is the evidence from our domestic animals of many kinds which have run wild in several parts of the world; if the statements of the rate of increase of slow-breeding cattle and horses in South America, and latterly in Australia, had not been well authenticated, they would have been quite incredible. So it is with plants: cases could be given of introduced plants which have become common throughout whole islands in a period of less than ten years. Several of the plants now most numerous over the wide plains of La Plata, clothing square leagues of surface almost to the exclusion of all other plants, have been introduced from Europe; and there are plants which now range in India, as I hear from Dr. Falconer, from Cape Comorin to the Himalaya, which have been imported from America since its discovery. In such cases, and endless instances could be given, no one supposes that the fertility of these animals or plants has been suddenly and temporarily increased in any sensible degree. The obvious explanation is, that the conditions of life have been very favorable, and that there has consequently been less destruction of the old and young, and that nearly all the young have been enabled to breed. In such cases the geometrical ratio of increase, the result of which never fails to be surprising, simply explains the extraordinarily rapid increase and wide diffusion of naturalized productions in their new homes."--(pp. 64, 65.) "All plants and animals are tending to increase at a geometrical ratio; all would most rapidly stock any station in which they could anyhow exist; the increase must be checked by destruction at some period of life."--(p. 65.) The difference between the most and the least prolific species is of no account: "The condor lays a couple of eggs, and the ostrich a score; and yet in the same country the condor may be the more numerous of the two. The Fulmar petrel lays but one egg, yet it is believed to be the most numerous bird in the world."--(p. 68.) "The amount of food gives the extreme limit to which each species can increase; but very frequently it is not the obtaining of food, but the serving as prey to other animals, which determines the average numbers of species."--(p. 68.) "Climate plays an important part in determining the average numbers of a species, and periodical seasons of extreme cold or drought I believe to be the most effective of all checks. I estimated that the winter of 1854--'55 destroyed four-fifths of the birds in my own grounds; and this is a tremendous destruction, when we remember that ten per cent, is an extraordinarily severe mortality from epidemics with man. The action of climate seems at first sight to be quite independent of the struggle for existence; but, in so far as climate chiefly acts in reducing food, it brings on the most severe struggle between the individuals, whether of the same or of distinct species, which subsist on the same kind of food, Even when climate, for instance extreme cold, acts directly, it will be the least vigorous, or those which have got least food through the advancing winter, which will suffer most. When we travel from south to north, or from a damp region to a dry, we invariably see some species gradually getting rarer and rarer, and finally disappearing; and, the change of climate being conspicuous, we are tempted to attribute the whole effect to its direct action. But this is a very false view; we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food; and if these enemies or competitors be in the least degree favored by any slight change of climate, they will increase in numbers, and, as each area is already stocked with inhabitants, the other species will decrease. When we travel southward and see a species decreasing in numbers, we may feel sure that the cause lies quite as much in other species being favored as in this one being hurt. So it is when we travel northward, but in a somewhat lesser degree, for the number of species of all kinds, and therefore of competitors, decreases northward; hence, in going northward, or in ascending a mountain, we far oftener meet with stunted forms, due to the directly injurious action of climate, than we do in proceeding southward or in descending a mountain. When we reach the arctic regions, or snow-capped summits, or absolute deserts, the struggle for life is almost exclusively with the elements. "That climate acts in main part indirectly by favoring other species, we may clearly see in the prodigious number of plants in our gardens which can perfectly well endure our climate, but which never become naturalized, for they cannot compete with our native plants, nor resist destruction by our native animals."--(pp. 68, 69.) After an instructive instance in which "cattle absolutely determine the existence of the Scotch fir," we are referred to cases in which insects determine the existence of cattle: "Perhaps Paraguay offers the most curious instance of this; for here neither cattle, nor horses, nor dogs, have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater number in Paraguay of a certain fly, which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers are probably regulated by hawks or beasts of prey) were to increase in Paraguay, the flies would decrease--then cattle and horses would become feral, and this would certainly greatly alter (as indeed I have observed in parts of South America) the vegetation; this, again, would largely affect the insects; and this, as we have just seen in Staffordshire, the insectivorous birds, and so onward in ever-increasing circles of complexity. We began this series by insectivorous birds, and we had ended with them. Not that in Nature the relations can ever be as simple as this. Battle within battle must ever be recurring with varying success; and yet in the long-run the forces are so nicely balanced that the face of Nature remains uniform for long periods of time, though assuredly the merest trifle would often give the victory to one organic being over another. Nevertheless, so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life!"--(pp. 72, 73.) "When we look at the plants and bushes clothing an entangled bank, we arc tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this! Every one has heard that when an American forest is cut down, a very different vegetation springs up; but it has been observed that the trees now growing on the ancient Indian mounds, in the Southern United States, display the same beautiful diversity and proportion of kinds as in the surrounding virgin forests. What a struggle between the several kinds of trees must here have gone on during long centuries, each annually scattering its seeds by the thousand; what war between insect and insect--between insects, snails, and other animals, with birds and beasts of prey--all striving to increase, and all feeding on each other or on the trees, or their seeds and seedlings, or on the other plants which first clothed the ground and thus checked the growth of the trees! Throw up a handful of feathers, and all must fall to the ground according to definite laws; but how simple is this problem compared to the action and reaction of the innumerable plants and animals which have determined, in the course of centuries, the proportional numbers and kinds of trees now growing on the old Indian ruins!"--(pp. 74, 75.) For reasons obvious upon reflection, the competition is often, if not generally, most severe between nearly related species when they are in contact, so that one drives the other before it, as the Hanoverian the old English rat, the small Asiatic cockroach in Russia, its greater congener, etc. And this, when duly considered, explains many curious results; such, for instance, as the considerable number of different genera of plants and animals which are generally found to inhabit any limited area. "The truth of the principle that the greatest amount of life can be supported by great diversification of structure is seen under many natural circumstances. In an extremely small area, especially if freely open to immigration, and where the contest between individual and individual must be severe, we always find great diversity in its inhabitants. For instance, I found that a piece of turf, three feet by four in size, which had been exposed for many years to exactly the same conditions, supported twenty species of plants, and these belonged to eighteen genera, and to eight orders, which showed how much these plants differed from each other. So it is with the plants and insects on small and uniform islets; and so in small ponds of fresh water. Farmers find that they can raise most food by a rotation of plants belonging to the most different orders; Nature follows what may be called a simultaneous rotation. Most of the animals and plants which live close round any small piece of ground could live on it (supposing it not to be in any way peculiar in its nature), and may be said to be striving to the utmost to live there; but it is seen that, where they come into the closest competition with each other, the advantages of diversification of structure, with the accompanying differences of habit and constitution, determine that the inhabitants, which thus jostle each other most closely, shall, as a general rule, belong to what we call different genera and orders."--(p. 114.) The abundance of some forms, the rarity and final extinction of many others, and the consequent divergence of character or increase of difference among the surviving representatives, are other consequences. As favored forms increase, the less favored must diminish in number, for there is not room for all; and the slightest advantage, at first probably inappreciable to human observation, must decide which shall prevail and which must perish, or be driven to another and for it more favorable locality. We cannot do justice to the interesting chapter upon natural selection by separated extracts. The following must serve to show how the principle is supposed to work: "If during the long course of ages, and under varying conditions of life, organic beings vary at all in the several parts of their organization, and I think this cannot be disputed; if there be, owing to the high geometrical powers of increase of each species, at some age, season, or year, a severe struggle for life, and this certainly cannot be disputed: then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of existence, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, I think it would be a most extraordinary fact if no variation ever had occurred useful to each being's own welfare, in the same way as so many variations have occurred useful to man. But if variations useful to any organic being do occur, assuredly individuals thus characterized will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly characterized. This principle of preservation I have called, for the sake of brevity, Natural Selection."--(pp. 126, 127.) "In order to make it clear how, as I believe, natural selection acts, I must beg permission to give one or two imaginary illustrations. Let us take the case of a wolf, which preys on various animals, securing some by craft, some by strength, and some by fleetness; and let us suppose that the fleetest prey, a deer for instance, had from any change in the country increased in numbers, or that other prey had decreased in numbers, during that season of the year when the wolf is hardest pressed for food. I can under such circumstances see no reason to doubt that the swiftest and slimmest wolves would have the best chance of surviving, and so be preserved or selected--provided always that they retained strength to master their prey at this or at some other period of the year, when they might be compelled to prey on other animals. I can see no more reason to doubt this than that man can improve the fleetness of his greyhounds by careful and methodical selection, or by that unconscious selection which results from each man trying to keep the best dogs without any thought of modifying the breed. "Even without any change in the proportional numbers of the animals on which our wolf preyed, a cub might be born with an innate tendency to pursue certain kinds of prey. Nor can this be thought very improbable; for we often observe great differences in the natural tendencies of our domestic animals: one cat, for instance, taking to catching rats, another mice; one cat, according to Mr. St. John, bringing home winged game, another hares or rabbits, and another hunting on marshy ground!, and almost nightly catching woodcocks or snipes. The tendency to catch rats rather than mice is known to be inherited. Now, if any slight innate change of habit or of structure benefited an individual wolf, it would have the best chance of surviving and of leaving offspring. Some of its young would probably inherit the same habits or structure, and by the repetition of this process a new variety might be formed which would either supplant or coexist with the parent-form of wolf. Or, again, the wolves inhabiting a mountainous district, and those frequenting the lowlands, would naturally be forced to hunt different prey; and from a continued preservation of the individuals best fitted for the two sites, two varieties might slowly be formed. These varieties would cross and blend where they met; but to this subject of intercrossing we shall soon have to return. I may add that, according to Mr. Pierce, there are two varieties of the wolf inhabiting the Catskill Mountains in the United States, one with a light greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which more frequently attacks the shepherd's flock."--(pp. 90, 91.) We eke out the illustration here with a counterpart instance, viz., the remark of Dr. Bachman that "the deer that reside permanently in the swamps of Carolina are taller and longer-legged than those in the higher grounds." [I-10] The limits allotted to this article are nearly reached, yet only four of the fourteen chapters of the volume have been touched. These, however, contain the fundamental principles of the theory, and most of those applications of it which are capable of something like verification, relating as they do to the phenomena now occurring. Some of our extracts also show how these principles are thought to have operated through the long lapse of the ages. The chapters from the sixth to the ninth inclusive are designed to obviate difficulties and objections, "some of them so grave that to this day," the author frankly says, he "can never reflect on them without being staggered." We do not wonder at it. After drawing what comfort he can from "the imperfection of the geological record" (Chapter IX), which we suspect is scarcely exaggerated, the author considers the geological succession of organic beings (Chapter X), to see whether they better accord with the common view of the immutability of species, or with that of their slow and gradual modification. Geologists must settle that question. Then follow two most interesting and able chapters on the geographical distribution of plants and animals, the summary of which we should be glad to cite; then a fitting chapter upon classification, morphology, embryology, etc., as viewed in the light of this theory, closes the argument; the fourteenth chapter being a recapitulation. The interest for the general reader heightens as the author advances on his perilous way and grapples manfully with the most formidable difficulties. To account, upon these principles, for the gradual elimination and segregation of nearly allied forms--such as varieties, sub-species, and closely-related or representative species--also in a general way for their geographical association and present range, is comparatively easy, is apparently within the bounds of possibility. Could we stop here we should be fairly contented. But, to complete the system, to carry out the principles to their ultimate conclusion, and to explain by them many facts in geographical distribution which would still remain anomalous, Mr. Darwin is equally bound to account for the formation of genera, families, orders, and even classes, by natural selection. He does "not doubt that the theory of descent with modification embraces all the members of the same class," and he concedes that analogy would press the conclusion still further; while he admits that "the more distinct the forms are, the more the arguments fall away in force." To command assent we naturally require decreasing probability to be overbalanced by an increased weight of evidence. An opponent might plausibly, and perhaps quite fairly, urge that the links in the chain of argument are weakest just where the greatest stress falls upon them. To which Mr. Darwin's answer is, that the best parts of the testimony have been lost. He is confident that intermediate forms must have existed; that in the olden times when the genera, the families, and the orders, diverged from their parent stocks, gradations existed as fine as those which now connect closely related species with varieties. But they have passed and left no sign. The geological record, even if all displayed to view, is a book from which not only many pages, but even whole alternate chapters, have been lost out, or rather which were never printed from the autographs of Nature. The record was actually made in fossil lithography only at certain times and under certain conditions (i.e., at periods of slow subsidence and places of abundant sediment); and of these records all but the last volume is out of print; and of its pages only local glimpses have been obtained. Geologists, except Lyell, will object to this--some of them moderately, others with vehemence. Mr. Darwin himself admits, with a candor rarely displayed on such occasions, that he should have expected more geological evidence of transition than he finds, and that all the most eminent paleontologists maintain the immutability of species. The general fact, however, that the fossil fauna of each period as a whole is nearly intermediate in character between the preceding and the succeeding faunas, is much relied on. We are brought one step nearer to the desired inference by the similar "fact, insisted on by all paleontologists, that fossils from two consecutive formations are far more closely related to each other than are the fossils of two remote formations. Pictet gives a well-known instance--the general resemblance of the organic remains from the several stages of the chalk formation, though the species are distinct at each stage. This fact alone, from its generality, seems to have shaken Prof. Pictet in his firm belief in the immutability of species" (p. 335). What Mr. Darwin now particularly wants to complete his inferential evidence is a proof that the same gradation may be traced in later periods, say in the Tertiary, and between that period and the present; also that the later gradations are finer, so as to leave it doubtful whether the succession is one of species--believed on the one theory to be independent, on the other, derivative--or of varieties, which are confessedly derivative. The proof of the finer gradation appears to be forthcoming. Des Hayes and Lyell have concluded that many of the middle Tertiary and a large proportion of the later Tertiary mollusca are specifically identical with living species; and this is still the almost universally prevalent view. But Mr. Agassiz states that, "in every instance where he had sufficient materials, he had found that the species of the two epochs supposed to be identical by Des Hayes and Lyell were in reality distinct, although closely allied species."[I-11] Moreover, he is now satisfied, as we understand, that the same gradation is traceable not merely in each great division of the Tertiary, but in particular deposits or successive beds, each answering to a great number of years; where what have passed unquestioned as members of one species, upon closer examination of numerous specimens exhibit differences which in his opinion entitle them to be distinguished into two, three, or more species. It is plain, therefore, that whatever conclusions can be fairly drawn from the present animal and vegetable kingdoms in favor of a gradation of varieties into species, or into what may be regarded as such, the same may be extended to the Tertiary period. In both cases, what some call species others call varieties; and in the later Tertiary shells this difference in judgment affects almost half of the species! We pass to a second difficulty in the way of Mr. Darwin's theory; to a case where we are perhaps entitled to demand of him evidence of gradation like that which connects the present with the Tertiary mollusca. Wide, very wide is the gap, anatomically and physiologically (we do not speak of the intellectual) between the highest quadrumana and man; and comparatively recent, if ever, must the line have bifurcated. But where is there the slightest evidence of a common progenitor? Perhaps Mr. Darwin would reply by another question: where are the fossil remains of the men who made the flint knives and arrowheads of the Somme Valley? We have a third objection, one, fortunately, which has nothing to do with geology. We can only state it here in brief terms. The chapter on hybridism is most ingenious, able, and instructive. If sterility of crosses is a special original arrangement to prevent the confusion of species by mingling, as is generally assumed, then, since varieties cross readily and their offspring is fertile inter se, there is a fundamental distinction between varieties and species. Mr. Darwin therefore labors to show that it is not a special endowment, but an incidental acquirement. He does show that the sterility of crosses is of all degrees; upon which we have only to say, Natura non facit saltum, here any more than elsewhere. But, upon his theory he is bound to show how sterility might be acquired, through natural selection or through something else. And the difficulty is, that, whereas individuals of the very same blood tend to be sterile, and somewhat remoter unions diminish this tendency, and when they have diverged into two varieties the cross-breeds between the two are more fertile than either pure stock--yet when they have diverged only one degree more the whole tendency is reversed, and the mongrel is sterile, either absolutely or relatively. He who explains the genesis of species through purely natural agencies should assign a natural cause for this remarkable result; and this Mr. Darwin has not done. Whether original or derived, however, this arrangement to keep apart those forms which have, or have acquired (as the case may be), a certain moderate amount of difference, looks to us as much designed for the purpose, as does a rachet to prevent reverse motion in a wheel. If species have originated by divergence, this keeps them apart. Here let us suggest a possibly attainable test of the theory of derivation, a kind of instance which Mr. Darwin may be fairly asked to produce--viz., an instance of two varieties, or what may be assumed as such, which have diverged enough to reverse the movement, to bring out some sterility in the crosses. The best marked human races might offer the most likely case. If mulattoes are sterile or tend to sterility, as some naturalists confidently assert, they afford Mr. Darwin a case in point. If, as others think, no such tendency is made out, the required evidence is wanting. A fourth and the most formidable difficulty is that of the production and specialization of organs. It is well said that all organic beings have been formed on two great laws: unity of type, and adaptation to the conditions of existence.[I-12] The special teleologists, such as Paley, occupy themselves with the latter only; they refer particular facts to special design, but leave an overwhelming array of the widest facts inexplicable. The morphologists build on unity of type, or that fundamental agreement in the structure of each great class of beings which is quite independent of their habits or conditions of life; which requires each individual "to go through a certain formality," and to accept, at least for a time, certain organs, whether they are of any use to him or not. Philosophical minds form various conceptions for harmonizing the two views theoretically. Mr. Darwin harmonizes and explains them naturally. Adaptation to the conditions of existence is the result of natural selection; unity of type, of unity of descent. Accordingly, as he puts his theory, he is bound to account for the origination of new organs, and for their diversity in each great type, for their specialization, and every adaptation of organ to function and of structure to condition, through natural agencies. Whenever he attempts this he reminds us of Lamarck, and shows us how little light the science of a century devoted to structural investigation has thrown upon the mystery of organization. Here purely natural explanations fail. The organs being given, natural selection may account for some improvement; if given of a variety of sorts or grades, natural selection might determine which should survive and where it should prevail. On all this ground the only line for the theory to take is to make the most of gradation and adherence to type as suggestive of derivation, and unaccountable upon any other scientific view--deferring all attempts to explain how such a metamorphosis was effected, until naturalists have explained how the tadpole is metamorphosed into a frog, or one sort of polyp into another. As to why it is so, the philosophy of efficient cause, and even the whole argument from design, would stand, upon the admission of such a theory of derivation, precisely where they stand without it. At least there is, or need be, no ground of difference here between Darwin and Agassiz. The latter will admit, with Owen and every morphologist, that hopeless is the attempt to explain the similarity of pattern in members of the same class by utility or the doctrine of final causes. "On the ordinary view of the independent creation of each being, we can only say that so it is, that it has so pleased the Creator to construct each animal and plant." Mr. Darwin, in proposing a theory which suggests a how that harmonizes these facts into a system, we trust implies that all was done wisely, in the largest sense designedly, and by an intelligent first cause. The contemplation of the subject on the intellectual side, the amplest exposition of the unity of plan in creation, considered irrespective of natural agencies, leads to no other conclusion. We are thus, at last, brought to the question, What would happen if the derivation of species were to be substantiated, either as a true physical theory, or as a sufficient hypothesis? What would come of it? The inquiry is a pertinent one, just now. For, of those who agree with us in thinking that Darwin has not established his theory of derivation many will admit with us that he has rendered a theory of derivation much less improbable than before; that such a theory chimes in with the established doctrines of physical science, and is not unlikely to be largely accepted long before it can be proved. Moreover, the various notions that prevail--equally among the most and the least religious--as to the relations between natural agencies or phenomena and efficient cause, are seemingly more crude, obscure, and discordant, than they need be. It is not surprising that the doctrine of the book should be denounced as atheistical. What does surprise and concern us is, that it should be so denounced by a scientific man, on the broad assumption that a material connection between the members of a series of organized beings is inconsistent with the idea of their being intellectually connected with one another through the Deity, i.e., as products of one mind, as indicating and realizing a preconceived plan. An assumption the rebound of which is somewhat fearful to contemplate, but fortunately one which every natural birth protests against. It would be more correct to say that the theory in itself is perfectly compatible with an atheistic view of the universe. That is true; but it is equally true of physical theories generally. Indeed, it is more true of the theory of gravitation, and of the nebular hypothesis, than of the hypothesis in question. The latter merely takes up a particular, proximate cause, or set of such causes, from which, it is argued, the present diversity of species has or may have contingently resulted. The author does not say necessarily resulted; that the actual results in mode and measure, and none other, must have taken place. On the other hand, the theory of gravitation and its extension in the nebular hypothesis assume a universal and ultimate physical cause, from which the effects in Nature must necessarily have resulted. Now, it is not thought, at least at the present day, that the establishment of the Newtonian theory was a step toward atheism or pantheism. Yet the great achievement of Newton consisted in proving that certain forces (blind forces, so far as the theory is concerned), acting upon matter in certain directions, must necessarily produce planetary orbits of the exact measure and form in which observation shows them to exist--a view which is just as consistent with eternal necessity, either in the atheistic or the pantheistic form, as it is with theism. Nor is the theory of derivation particularly exposed to the charge of the atheism of fortuity; since it undertakes to assign real causes for harmonious and systematic results. But, of this, a word at the close. The value of such objections to the theory of derivation may be tested by one or two analogous cases. The common scientific as well as popular belief is that of the original, independent creation of oxygen and hydrogen, iron, gold, and the like. Is the speculative opinion now increasingly held, that some or all of the supposed elementary bodies are derivative or compound, developed from some preceding forms of matter, irreligious? Were the old alchemists atheists as well as dreamers in their attempts to transmute earth into gold? Or, to take an instance from force (power)--which stands one step nearer to efficient cause than form--was the attempt to prove that heat, light, electricity, magnetism, and even mechanical power, are variations or transmutations of one force, atheistical in its tendency? The supposed establishment of this view is reckoned as one of the greatest scientific triumphs of this century. Perhaps, however, the objection is brought, not so much against the speculation itself, as against the attempt to show how derivation might have been brought about. Then the same objection applies to a recent ingenious hypothesis made to account for the genesis of the chemical elements out of the ethereal medium, and to explain their several atomic weights and some other characteristics by their successive complexity--hydrogen consisting of so many atoms of ethereal substance united in a particular order, and so on. The speculation interested the philosophers of the British Association, and was thought innocent, but unsupported by facts. Surely Mr. Darwin's theory is none the worse, morally, for having some foundation in fact. In our opinion, then, it is far easier to vindicate a theistic character for the derivative theory, than to establish the theory itself upon adequate scientific evidence. Perhaps scarcely any philosophical objection can be urged against the former to which the nebular hypothesis is not equally exposed. Yet the nebular hypothesis finds general scientific acceptance, and is adopted as the basis of an extended and recondite illustration in Mr. Agassiz's great work.[I-13] How the author of this book harmonizes his scientific theory with his philosophy and theology, he has not informed us. Paley in his celebrated analogy with the watch, insists that if the timepiece were so constructed as to produce other similar watches, after a manner of generation in animals, the argument from design would be all the stronger. What is to hinder Mr. Darwin from giving Paley's argument a further a-fortiori extension to the supposed case of a watch which sometimes produces better watches, and contrivances adapted to successive conditions, and so at length turns out a chronometer, a town clock, or a series of organisms of the same type? From certain incidental expressions at the close of the volume, taken in connection with the motto adopted from Whewell, we judge it probable that our author regards the whole system of Nature as one which had received at its first formation the impress of the will of its Author, foreseeing the varied yet necessary laws of its action throughout the whole of its existence, ordaining when and bow each particular of the stupendous plan should be realized in effect, and--with Him to whom to will is to do--in ordaining doing it, Whether profoundly philosophical or not, a view maintained by eminent philosophical physicists and theologians, such as Babbage on the one hand and Jowett on the other, will hardly be denounced as atheism. Perhaps Mr. Darwin would prefer to express his idea in a more general way, by adopting the thoughtful words of one of the most eminent naturalists of this or any age, substituting the word action for "thought," since it is the former (from which alone the latter can be inferred) that he has been considering. "Taking Nature as exhibiting thought for my guide, it appears to me that while human thought is consecutive, Divine thought is simultaneous, embracing at the same time and forever, in the past, the present and the future, the most diversified relations among hundreds of thousands of organized beings, each of which may present complications again, which to study and understand even imperfectly--as for instance man himself-- mankind has already spent thousands of years."[I-14] In thus conceiving of the Divine Power in act as coetaneous with Divine Thought, and of both as far as may be apart from the human element of time, our author may regard the intervention of the Creator either as, humanly speaking, done from all time, or else as doing through all time. In the ultimate analysis we suppose that every philosophical theist must adopt one or the other conception. A perversion of the first view leads toward atheism, the notion of an eternal sequence of cause and effect, for which there is no first cause--a view which few sane persons can long rest in. The danger which may threaten the second view is pantheism. We feel safe from either error, in our profound conviction that there is order in the universe; that order presupposes mind; design, will; and mind or will, personality. Thus guarded, we much prefer the second of the two conceptions of causation, as the more philosophical as well as Christian view--a view which leaves us with the same difficulties and the same mysteries in Nature as in Providence, and no other. Natural law, upon this view, is the human conception of continued and orderly Divine action. We do not suppose that less power, or other power, is required to sustain the universe and carry on its operations, than to bring it into being. So, while conceiving no improbability of "interventions of Creative mind in Nature," if by such is meant the bringing to pass of new and fitting events at fitting times, we leave it for profounder minds to establish, if they can, a rational distinction in kind between his working in Nature carrying on operations, and in initiating those operations. We wished, under the light of such views, to examine more critically the doctrine of this book, especially of some questionable parts; for instance, its explanation of the natural development of organs, and its implication of a "necessary acquirement of mental power" in the ascending scale of gradation. But there is room only for the general declaration that we cannot think the Cosmos a series which began with chaos and ends with mind, or of which mind is a result: that, if, by the successive origination of species and organs through natural agencies, the author means a series of events which succeed each other irrespective of a continued directing intelligence--events which mind does not order and shape to destined ends--then he has not established that doctrine, nor advanced toward its establishment, but has accumulated improbabilities beyond all belief. Take the formation and the origination of the successive degrees of complexity of eyes as a specimen. The treatment of this subject (pp. i88, 189), upon one interpretation, is open to all the objections referred to; but, if, on the other hand, we may rightly compare the eye "to a telescope, perfected by the long-continued efforts of the highest human intellects," we could carry out the analogy, and draw satisfactory illustrations and inferences from it. The essential, the directly intellectual thing is the making of the improvements in the telescope or the steam-engine. Whether the successive improvements, being small at each step, and consistent with the general type of the instrument, are applied to some of the individual machines, or entire new machines are constructed for each, is a minor matter. Though, if machines could engender, the adaptive method would be most economical; and economy is said to be a paramount law in Nature. The origination of the improvements, and the successive adaptations to meet new conditions or subserve other ends, are what answer to the supernatural, and therefore remain inexplicable. As to bringing them into use, though wisdom foresees the result, the circumstances and the natural competition will take care of that, in the long-run. The old ones will go out of use fast enough, except where an old and simple machine remains still best adapted to a particular purpose or condition--as, for instance, the old Newcomen engine for pumping out coal-pits. If there's a Divinity that shapes these ends, the whole is intelligible and reasonable; otherwise, not. We regret that the necessity of discussing philosophical questions has prevented a fuller examination of the theory itself, and of the interesting scientific points which are brought to bear in its favor. One of its neatest points, certainly a very strong one for the local origination of species, and their gradual diffusion under natural agencies, we must reserve for some other convenient opportunity. The work is a scientific one, rigidly restricted to its direct object; and by its science it must stand or fall. Its aim is, probably, not to deny creative intervention in Nature--for the admission of the independent origination of certain types does away with all antecedent improbability of as much intervention as may be required--but to maintain that Natural Selection, in explaining the facts, explains also many classes of facts which thousand-fold repeated independent acts of creation do not explain, but leave more mysterious than ever. How far the author has succeeded, the scientific world will in due time be able to pronounce. As these sheets are passing through the press, a copy of the second edition has reached us. We notice with pleasure the insertion of an additional motto on the reverse of the title page, directly claiming the theistic view which we have vindicated for the doctrine. Indeed, these pertinent words of the eminently wise Bishop Butler comprise, in their simplest expression, the whole substance of our later pages: "The only distinct meaning of the word 'natural' is stated, fixed, or settled; since what is natural as much requires and presupposes an intelligent mind to render it so, i.e., to effect it continually or at stated times, as what is supernatural or miraculous does to effect it for once." II DESIGN VERSUS NECESSITY DISCUSSION BETWEEN TWO READERS OF DARWIN'S TREATISE ON THE ORIGIN OF SPECIES, UPON ITS NATURAL THEOLOGY (American Journal of Science and Arts, September, 1860) D.T.--Is Darwin's theory atheistic or pantheistic? or, does it tend to atheism or pantheism? Before attempting any solution of this question, permit me to say a few words tending to obtain a definite conception of necessity and design, as the sources from which events may originate, each independent of the other; and we shall, perhaps, best attain a clear understanding of each, by the illustration of an example in which simple human designers act upon the physical powers of common matter. Suppose, then, a square billiard-table to be placed with its corners directed to the four cardinal points. Suppose a player, standing at the north corner, to strike a red ball directly to the south, his design being to lodge the ball in the south pocket; which design, if not interfered with, must, of course be accomplished. Then suppose another player, standing at the east corner, to direct a white ball to the west corner. This design also, if not interfered with, must be accomplished. Next suppose both players to strike their balls at the same instant, with like forces, in the directions before given. In this case the balls would not pass as before, namely, the red ball to the south, and the white ball to the west, but they must both meet and strike each other in the centre of the table, and, being perfectly elastic, the red ball must pass to the west pocket, and the white ball to the south pocket. We may suppose that the players acted wholly without concert with each other, indeed, they may be ignorant of each other' s design, or even of each other's existence; still we know that the events must happen as herein described. Now, the first half of the course of these two balls is from an impulse, or proceeds from a power, acting from design. Each player has the design of driving his ball across the table in a diagonal line to accomplish its lodgment at the opposite corner of the table. Neither designed that his ball should be deflected from that course and pass to another corner of the table. The direction of this second part of the motion must be referred entirely to necessity, which directly interferes with the purpose of him who designed the rectilinear direction. We are not, in this case, to go back to find design in the creation of the powers or laws of inertia and elasticity, after the order of which the deflection, at the instant of collision, necessarily takes place. We know that these powers were inherent in the balls, and were not created to answer this special deflection. We are required, by the hypothesis, to confine attention in point of time, from the instant preceding the impact of the balls, to the time of their arrival at the opposite corners of the table. The cues aremoved by design. The impacts are acts from design. The first half of the motion of each ball is under the direction of design. We mean by this the particular design of each player. But, at the instant of the collision of the balls upon each other, direction from design ceases, and the balls no longer obey the particular designs of the players, the ends or purposes intended by them are not accomplished, but frustrated, by necessity, or by the necessary action of the powers of inertia and elasticity, which are inherent in matter, and are not made by any design of a Creator for this special action, or to serve this special purpose, but would have existed in the materials of which the balls were made, although the players had never been born. I have thus stated, by a simple example in physical action, what is meant by design and what by necessity; and that the latter may exist without any dependence upon the former. If I have given the statement with what may be thought, by some, unnecessary prolixity, I have only to say that I have found many minds to have a great difficulty in conceiving of necessity as acting altogether independent of design. Let me now trace these principles as sources of action in Darwin's work or theory. Let us see how much there is of design acting to produce a foreseen end, and thus proving a reasoning and self-conscious Creator; and how much of mere blind power acting without rational design, or without a specific purpose or conscious foresight. Mr. Darwin has specified in a most clear and unmistakable manner the operation of his three great powers, or rather, the three great laws by which the organic power of life acts in the formation of an eye. (See p. 169.) Following the method he has pointed out, we will take a number of animals of the same species, in which the eye is not developed. They may have all the other senses, with the organs of nutrition, circulation, respiration, and locomotion. They all have a brain and nerves, and some of these nerves may be sensitive to light; but have no combination of retina, membranes, humors, etc., by which the distinct image of an object may be formed and conveyed by the optic nerve to the cognizance of the internal perception, or the mind. The animal in this case would be merely sensible of the difference between light and darkness. He would have no power of discriminating form, size, shape, or color, the difference of objects, and to gain from these a knowledge of their being useful or hurtful, friends or enemies. Up to this point there is no appearance of necessity upon the scene. The billiard-balls have not yet struck together, and we will suppose that none of the arguments that may be used to prove, from this organism, thus existing, that it could not have come into form and being without a creator acting to this end with intelligence and design, are opposed by anything that can be found in Darwin's theory; for, so far, Darwin's laws are supposed not to have come into operation. Give the animals, thus organized, food and room, and they may go on, from generation to generation, upon the same organic level. Those individuals that, from natural variation, are born with light-nerves a little more sensitive to light than their parents, will cross or interbreed with those who have the same organs a little less sensitive, and thus the mean standard will be kept up without any advancement. If our billiard-table were sufficiently extensive, i. e., infinite, the balls rolled from the corners would never meet, and the necessity which we have supposed to deflect them would never act. The moment, however, that the want of space or food commences natural selection begins. Here the balls meet, and all future action is governed by necessity. The best forms, or those nerves most sensitive to light, connected with incipient membranes and humors for corneas and lenses, are picked out and preserved by natural selection, of necessity. All cannot live and propagate, and it is a necessity, obvious to all, that the weaker must perish, if the theory be true. Working on, in this way, through countless generations, the eye is at last 55 formed in all its beauty and excellence. It must (always assuming that this theory is true) result from this combined action of natural variation, the struggle for life, and natural selection, with as much certainty as the balls, after collision, must pass to corners of the table different from those to which they were directed, and so far forth as the eye is formed by these laws, acting upward from the nerve merely sensitive to light, we can no more infer design, and from design a designer, than we can infer design in the direction of the billiard-balls after the collision. Both are sufficiently accounted for by blind powers acting under a blind necessity. Take away the struggle for life from the one, and the collision of the balls from the other--and neither of these was designed--and the animal would have gone on without eyes. The balls would have found the corners of the table to which they were first directed. While, therefore, it seems to me clear that one who can find no proof of the existence of an intelligent Creator except through the evidence of design in the organic world, can find no evidence of such design in the construction of the eye, if it were constructed under the operation of Darwin's laws, I shall not for one moment contend that these laws are incompatible with design and a self-conscious, intelligent Creator. Such design might, indeed, have coexisted with the necessity or natural selection; and so the billiard-players might have �designed the collision of their balls; but neither the formation of the eye, nor the path of the balls after collision, furnishes any sufficient proof of such design in either case. One, indeed, who believes, from revelation or any other cause, in the existence of such a Creator, the fountain and Source of all things in heaven above and in the earth beneath, will see in natural variation, the struggle for life, and natural selection, only the order or mode in which this Creator, in his �own perfect wisdom, sees fit to act. Happy is he who can thus see and adore. But how many are there who have no such 56 belief from intuition, or faith in revelation; but who have by careful and elaborate search in the physical, and more especially in the organic world, inferred, by induction, the existence of God from what has seemed to them the wonderful adaptation of the different organs and parts of the animal body to its, apparently, designed ends! Imagine a mind of this skeptical character, in all honesty and under its best reason, after finding itself obliged to reject the evidence of revelation, to commence a search after the Creator, in the light of natural theology. He goes through the proof for final cause and design, as given in a summary though clear, plain, and convincing form, in the pages of Paley and the "Bridgewater Treatises." The eye and the hand, those perfect instruments of optical and mechanical contrivance and adaptation, without the least waste or surplusage--these, say Paley and Bell, certainly prove a designing maker as much as the palace or the watch proves an architect or a watchmaker. Let this mind, in this state, cross Darwin's work, and find that, after a sensitive nerve or a rudimentary hoof or claw, no design is to be found. From this point upward the development is the mere necessary result of natural selection; and let him receive this law of natural selection as true, and where does he find himself? Before, he could refer the existence of the eye, for example, only to design, or chance. There was no other alternative. He rejected chance, as impossible. It must then be a design. But Darwin brings up another power, namely, natural selection, in place of this impossible chance. This not only may, but, according to Darwin, must of necessity produce an eye. It may indeed coexist with design, but it must exist and act and produce its results, even without design. Will such a mind, under such circumstances, infer the existence of the designer--God--when he can, at the same time, satisfactorily account for the thing produced, by the operation of this natural selection? It seems to me, therefore, perfectly evident 57 that the substitution of natural selection, by necessity, for design in the formation of the organic world, is a step decidedly atheistical. It is in vain to say that Darwin takes the creation of organic life, in its simplest forms, to have been the work of the Deity. In giving up design in these highest and most complex forms of organization, which have always been relied upon as the crowning proof of the existence of an intelligent Creator, without whose intellectual power they could not have been brought into being, he takes a most decided step to banish a belief in the intelligent action of God from the organic world. The lower organisms will go next. The atheist will say, Wait a little. Some future Darwin will show how the simple forms came necessarily from inorganic matter. This is but another step by which, according to Laplace, "the discoveries of science throw final causes further back." A.G.--It is conceded that, if the two players in the supposed case were ignorant of each other's presence, the designs of both were frustrated, and from necessity. Thus far it is not needful to inquire whether this necessary consequence is an unconditional or a conditioned necessity, nor to require a more definite statement of the meaning attached to the word necessity as a supposed third alternative. But, if the players knew of each other's presence, we could not infer from the result that the design of both or of either was frustrated. One of them may have intended to frustrate the other's design, and to effect his own. Or both may have been equally conversant with the properties of the matter and the relation of the forces concerned (whatever the cause, origin, or nature, of these forces and properties), and the result may have been according to the designs of both. As you admit that they might or might not have designed the collision of their balls and its consequences the question arises whether there is any way of ascertaining which of the two conceptions we may form about it is the true one. Now, let it be remarked that design can never be demonstrated. Witnessing the act does not make known the design, as we have seen in the case assumed for the basis of the argument. The word of the actor is not proof; and that source of evidence is excluded from the cases in question. The only way left, and the only possible way in cases where testimony is out of the question, is to infer the design from the result, or from arrangements which strike us as adapted or intended to produce a certain result, which affords a presumption of design. The strength of this presumption may be zero, or an even chance, as perhaps it is in the assumed case; but the probability of design will increase with the particularity of the act, the specialty of the arrangement or machinery, and with the number of identical or yet more of similar and analogous instances, until it rises to a moral certainty--i. e., to a conviction which practically we are as unable to resist as we are to deny the cogency of a mathematical demonstration. A single instance, or set of instances, of a comparatively simple arrangement might suffice. For instance, we should not doubt that a pump was designed to raise water by the moving of the handle. Of course, the conviction is the stronger, or at least the sooner arrived at, where we can imitate the arrangement, and ourselves produce the result at will, as we could with a pump, and also with the billiard-balls. And here I would suggest that your billiard-table, with the case of collision, answers well to a machine. In both a result is produced by indirection--by applying a force out of line of the ultimate direction. And, as I should feel as confident that a man intended to raise water who was working a pumphandle, as if he were bringing it up in pailfuls from below by means of a ladder, so, after due examination of the billiard-table and its appurtenances, I should probably think it likely that the effect of the rebound was expected and intended no less than that of the immediate impulse. And a similar inspection of arrangements and results in Nature would raise at least an equal presumption of design. You allow that the rebound might have been intended, but you require proof that it was. We agree that a single such instance affords no evidence either way. But how would it be if you saw the men doing the same thing over and over? and if they varied it by other arrangements of the balls or of the blow, and these were followed by analogous results? How if you at length discovered a profitable end of the operation, say the winning of a wager? So in the counterpart case of natural selection: must we not infer intention from the arrangements and the results? But I will take another case of the very same sort, though simpler, and better adapted to illustrate natural selection; because the change of direction--your necessity--acts gradually or successively, instead of abruptly. Suppose I hit a man standing obliquely in my rear, by throwing forward a crooked stick, called a boomerang. How could he know whether the blow was intentional or not? But suppose I had been known to throw boomerangs before; suppose that, on different occasions, I had before wounded persons by the same, or other indirect and apparently aimless actions; and suppose that an object appeared to be gained in the result--that definite ends were attained--would it not at length be inferred that my assault, though indirect, or apparently indirect, was designed? To make the case more nearly parallel with those it is brought to illustrate, you have only to suppose that, although the boomerang thrown by me went forward to a definite place, and at least appeared to subserve a purpose, and the bystanders, after a while, could get traces of the mode or the empirical law of its flight, yet they could not themselves do anything with it. It was quite beyond their power to use it. Would they doubt, or deny my intention, on that account? No: they would insist that design on my part must be presumed from the nature of the results; that, though design may have been wanting in any one case, yet the repetition of the result, and from different positions and under varied circumstances, showed that there must have been design. Moreover, in the way your case is stated, it seems to concede the most important half of the question, and so affords a presumption for the rest, on the side of design. For you seem to assume an actor, a designer, accomplishing his design in the first instance. You--a bystander--infer that the player effected his design in sending the first ball to the pocket before him. You infer this from observation alone. Must you not from a continuance of the same observation equally infer a common design of the two players in the complex result, or a design of one of them to frustrate the design of the other? If you grant a designing actor, the presumption of design is as strong, or upon continued observation of instances soon becomes as strong, in regard to the deflection of the balls, or variation of the species, as it was for the result of the first impulse or for the production of the original animal, etc. But, in the case to be illustrated, we do not see the player. We see only the movement of the balls. Now, if the contrivances and adaptations referred to really do "prove a designer as much as the palace or the watch proves an architect or a watchmaker"--as Paley and Bell argue, and as your skeptic admits, while the alternative is between design and chance--then they prove it with all the proof the case is susceptible of, and with complete conviction. For we cannot doubt that the watch had a watchmaker. And if they prove it on the supposition that the unseen operator acted immediately--i.e., that the player directly impelled the balls in the directions we see them moving, I insist that this proof is not impaired by our ascertaining that he acted mediately--i.e., that the present state or form of the plants or animals, like the present position of the billiard-balls, resulted from the collision of the individuals with one another, or with the surroundings. The original impulse, which we once supposed was in the line of the observed movement, only proves to have been in a different direction; but the series of movements took place with a series of results, each and all of them none the less determined, none the less designed. Wherefore, when, at the close, you quote Laplace, that "the discoveries of science throw final causes farther back," the most you can mean is, that they constrain us to look farther back for the impulse. They do not at all throw the argument for design farther back, in the sense of furnishing evidence or presumption that only the primary impulse was designed, and that all the rest followed from chance or necessity. Evidence of design, I think you will allow, everywhere is drawn from the observation of adaptations and of results, and has really nothing to do with anything else, except where you can take the word for the will. And in that case you have not argument for design, but testimony. In Nature we have no testimony; but the argument is overwhelming. Now, note that the argument of the olden time--that of Paley, etc., which your skeptic found so convincing--was always the argument for design in the movement of the balls after deflection. For it was drawn from animals produced by generation, not by creation, and through a long succession of generations or deflections. Wherefore, if the argument for design is perfect in the case of an animal derived from a long succession of individuals as nearly alike as offspring is generally like parents and grandparents, and if this argument is not weakened when a variation, or series of variations, has occurred in the course, as great as any variations we know of among domestic cattle, how then is it weakened by the supposition, or by the likelihood, that the variations have been twice or thrice as great as we formerly supposed, or because the variations have been "picked out," and a few of them pre served as breeders of still other variations, by natural selection? Finally let it be noted that your element of necessity has to do, so far as we know, only with the picking out and preserving of certain changing forms, i. e., with the natural selection. This selection, you may say, must happen under the circumstances. This is a necessary result of the collision of the balls; and these results can be predicted. If the balls strike so and so, they will be deflected so and so. But the variation itself is of the nature of an origination. It answers well to the original impulse of the balls, or to a series of such impulses. We cannot predict what particular new variation will occur from any observation of the past. Just as the first impulse was given to the balls at a point out of sight, so the impulse which resulted in the variety or new form was given at a point beyond observation, and is equally mysterious or unaccountable, except on the supposition of an ordaining will. The parent had not the peculiarity of the variety, the progeny has. Between the two is the dim or obscure region of the formation of a new individual, in some unknown part of which, and in some wholly unknown way, the difference is intercalated. To introduce necessity here is gratuitous and unscientific; but here you must have it to make your argument valid. I agree that, judging from the past, it is not improbable that variation itself may be hereafter shown to result from physical causes. When it is so shown, you may extend your necessity into this region, but not till then. But the whole course of scientific discovery goes to assure us that the discovery of the cause of variation will be only a resolution of variation into two factors: one, the immediate secondary cause of the changes, which so far explains them; the other an unresolved or unexplained phenomenon, which will then stand just where the product, variation, stands now, only that it will be one step nearer to the efficient cause. This line of argument appears to me so convincing, that I am bound to suppose that it does not meet your case. Although you introduced players to illustrate what design is, it is probable that you did not intend, and would not accept, the parallel which your supposed case suggested. When you declare that the proof of design in the eye and the hand, as given by Paley and Bell, was convincing, you mean, of course, that it was convincing, so long as the question was between design and chance, but that now another alternative is offered, one which obviates the force of those arguments, and may account for the actual results without design. I do not clearly apprehend this third alternative. Will you be so good, then, as to state the grounds upon which you conclude that the supposed proof of design from the eye, or the hand, as it stood before Darwin's theory was promulgated, would be invalidated by the admission of this new theory? D.T.--As I have ever found you, in controversy, meeting the array of your opponent fairly and directly, without any attempt to strike the body of his argument through an unguarded joint in the phraseology, I was somewhat surprised at the course taken in your answer to my statement on Darwin's theory. You there seem to suppose that I instanced the action of the billiard balls and players as a parallel, throughout, to the formation of the organic world. Had it occurred to me that such an application might be supposed to follow legitimately from my introduction of this action, I should certainly have stated that I did not intend, and should by no means accede to, that construction. My purpose in bringing the billiard-table upon the scene was to illustrate, by example, design and necessity, as different and independent sources from which results, it might indeed be identical results, may be derived All the conclusions, therefore, that you have arrived at through this misconception or misapplication of my illustration, I cannot take as an answer to the matter stated or intended to be stated by me. Again, following this misconception, you suppose the skeptic (instanced by me as revealing through the evidence of design, exhibited in the structure of the eye, for its designer, God) as bringing to the examination a belief in the existence of design in the construction of the animals as they existed up to the moment when the eye was, according to my supposition, added to the heart, stomach, brain, etc. By skeptic I, of course, intended one who doubted the existence of design in every organic structure, or at least required proof of such design. Now, as the watch may be instanced as a more complete exhibition of design than a flint knife or an hour-glass, I selected, after the example of Paley, the eye, as exhibiting by its complex but harmonious arrangements a higher evidence of design and a designer than is to be found in a nerve sensitive to light, or any mere rudimentary part or organ. I could not mean by skeptic one who believed in design so far as a claw, or a nerve sensitive to light, was concerned, but doubted all above. For one who believes in design at all will not fail to recognize it in a hand or an eye. But I need not extend these remarks, as you acknowledge in the sequel to your argument that you may not have suited it to the case as I have stated it. You now request me to "state the grounds upon which I conclude that the supposed proof of design from the eye and the hand, as it stood before Darwin's theory was promulgated, is invalidated by the admission of that theory." It seems to me that a sufficient answer to this question has already been made in the last part of my former paper; but, as you request it, I will go over the leading points as there given, with more minuteness of detail. Let us, then, suppose a skeptic, one who is yet considering and doubting of the existence of God, having already concluded that the testimony from any and all revelation is insufficient, and having rejected what is called the a priori arguments brought forward in natural theology, and pertinaciously insisted upon by Dr. Clark and others, turning as a last resource to the argument from design in the organic world. Voltaire tells him that a palace could not exist without an architect to design it. Dr. Paley tells him that a watch proves the design of a watchmaker. He thinks this very reasonable, and, although he sees a difference between the works of Nature and those of mere human art, yet if he can find in any organic body, or part of a body, the same adaptation to its use that he finds in a watch, this truth will go very far toward proving, if it is not entirely conclusive, that, in making it, the powers of life by which it grew were directed by an intelligent, reasoning master. Under the guidance of Paley he takes an eye, which, although an optical, and not a mechanical instrument like the watch, is as well adapted to testify to design. He sees, first, that the eye is transparent when every other part of the body is opaque. Was this the result of a mere Epicurean or Lucretian "fortuitous concourse" of living "atoms"? He is not yet certain it might not be so. Next he sees that it is spherical, and that this convex form alone is capable of changing the direction of the light which proceeds from a distant body, and of collecting it so as to form a distinct image within its globe. Next he sees at the exact place where this image must be formed a curtain of nerve-work, ready to receive and convey it, or excite from it, in its own mysterious way, an idea of it in the mind. Last of all, he comes to the crystalline lens. Now, he has before learned that without this lens an eye would by the aqueous and Vitreous humors alone form an image upon the retina, but this image would be indistinct from the light not being sufficiently refracted, and likewise from having a colored fringe round its edges. This last effect is attributable to the refrangibility of light, that is, to some of the colors being more refracted than others. He likewise knows that more than a hundred years ago Mr. Dollond having found out, after many experiments, that some kinds of glass have the power of dispersing light, for each degree of its refraction, much more than other kinds, and that on the discovery of this fact he contrived to make telescopes in which he passed the light through two object-glasses successively, one of which he made of crown and one of flint glass, so ground and adapted to each other that the greater dispersion produced by the substance of one should be corrected by the smaller dispersion of the other. This contrivance corrected entirely the colored images which had rendered all previous telescopes very imperfect. He finds in this invention all the elements of design, as it appeared in the thought and action of a human designer. First, conjecture of certain laws or facts in optics. Then, experiment proving these laws or facts. Then, the contrivance and formation of an instrument by which those laws or facts must produce a certain sought result. Thus enlightened, our skeptic turns to his crystalline lens to see if he can discover the work of a Dollond in this. Here he finds that an eye, having a crystalline lens placed between the humors, not only refracts the light more than it would be refracted by the humors alone, but that, in this combination of humors and lens, the colors are as completely corrected as in the combination of Dollond's telescope. Can it be that there was no design, no designer, directing the powers of life in the formation of this wonderful organ? Our skeptic is aware that, in the arts of man, great aid has been, sometimes, given by chance, that is, by the artist or workman observing some fortuitous combination, form, or action, around him. He has heard it said that the chance arrangement of two pairs of spectacles, in the shop of a Dutch optician, gave the direction 67 for constructing the first telescope. Possibly, in time, say a few geological ages, it might in some optician's shop have brought about a combination of flint and crown glass which, together, should have been achromatic. But the space between the humors of the eye is not an optician' s shop where object-glasses of all kinds, shapes, and sizes, are placed by chance, in all manner of relations and positions. On the hypothesis under which our skeptic is making his examination--the eye having been completed in all but the formation of the lens--the place which the lens occupies when completed was filled with parts of the humors and plane membrane, homogeneous in texture and surface, presenting, therefore, neither the variety of the materials nor forms which are contained in the optician's shop for chance to make its combinations with. How, then, could it be cast of a combination not before used, and fashioned to a shape different from that before known, and placed in exact combination with all the parts before enumerated, with many others not even mentioned? He sees no parallelism of condition, then, by which chance could act in forming a crystalline lens, which answers to the condition of an optician's shop, where it might be possible in many ages for chance to combine existing forms into an achromatic object-glass. Considering, therefore, the eye thus completed and placed in its bony case and provided with its muscles, its lids, its tear-ducts, and all its other elaborate and curious appendages, and, a thousand times more wonderful still, without being encumbered with a single superfluous or useless part, can he say that this could be the work of chance? The improbability of this is so great, and consequently the evidence of design is so strong, that he is about to seal his verdict in favor of design, when he opens Mr. Darwin's book. There he finds that an eye is no more than a vital aggregation or growth, directed, not by design nor chance, but moulded by natural variation and natural selection, through which it must, necessarily, have been developed and formed. Particles or atoms being aggregated by the blind powers of life, must become under the given conditions, by natural variation and natural selection, eyes, without design, as certainly as the red billiard-ball went to the west pocket, by the powers of inertia and elasticity, without the design of the hand that put it in motion. (See Darwin, p. 169.) Let us lay before our skeptic the way in which we may suppose that Darwin would trace the operation of life, or the vital force conforming to these laws. In doing this we need not go through with the formation of the several membranes, humors, etc., but take the crystalline lens as the most curious and nicely arranged and adapted of all the parts, and as giving, moreover, a close parallel, in the end produced, to that produced by design, by a human designer, Dollond, in forming his achromatic object-glass. If it can be shown that natural variation and natural selection were capable of forming the crystalline lens, it will not be denied that they were capable of forming the iris, the sclerotica, the aqueous humors, or any and all the other parts. Suppose, then, that we have a number of animals, with eyes yet wanting the crystalline. In this state the animals can see, but dimly and imperfectly, as a man sees after having been couched. Some of the offspring of these animals have, by natural variation, merely a portion of the membrane which separates the aqueous from the vitreous humor a little thickened in its middle part, a little swelled out. This refracts the light a little more than it would be refracted by a membrane in which no such swelling existed, and not only so, but, in combination with the humors, it corrects the errors of dispersion and makes the image somewhat more colorless. All the young animals that have this swelled membrane see more distinctly than their parents or brethren. They, therefore, have an advantage over them in the struggle for life. They can obtain food more easily; can find their prey, and escape from their enemies with greater facility than their kindred. This thickening and rounding of the membrane goes on from generation to generation by natural variation; natural selection all the while "picking out with unerring skill all the improvements, through countless generations," until at length it is found that the membrane has become a perfect crystalline lens. Now, where is the design in all this? The membrane was not thickened and rounded to the end that the image should be more distinct and colorless; but, being thickened and rounded by the operation of natural variation, inherent in generation, natural selection of necessity produced the result that we have seen. The same result was thus produced of necessity, in the eye, that Dollond came at, in the telescope, with design, through painful guessing, reasoning, experimenting, and forming. Suppose our skeptic to believe in all this power of natural selection; will he now seal up his verdict for design, with the same confidence that he would before he heard of Darwin? If not, then "the supposed proof from design is invalidated by Darwin's theory." A.G.--Waiving incidental points and looking only to the gist of the question, I remark that the argument for design as against chance, in the formation of the eye, is most convincingly stated in your argument. Upon this and upon numerous similar arguments the whole question we are discussing turns. So, if the skeptic was about to seal his verdict in favor of design, and a designer, when Darwin's book appeared, why should his verdict now be changed or withheld? All the facts about the eye, which convinced him that the organ was designed, remain just as they were. His conviction was not produced through testimony or eyewitness, but design was irresistibly inferred from the evidence of contrivance in the eye itself. Now, if the eye as it is, or has become, so convincingly argued design why not each particular step or part of this result? If the production of a perfect crystalline lens in the eye--you know not how--as much indicated design as did the production of a Dollond achromatic lens--you understand how--then why does not "the swelling out" of a particular portion of the membrane behind the iris--caused you know not how--which, by "correcting the errors of dispersion and making the image somewhat more colorless," enabled the "young animals to see more distinctly than their parents or brethren," equally indicate design--if not as much as a perfect crystalline, or a Dollond compound lens, yet as much as a common spectacle-glass? Darwin only assures you that what you may have thought was done directly and at once was done indirectly and successively. But you freely admit that indirection and succession do not invalidate design, and also that Paley and all the natural theologians drew the arguments which convinced your skeptic wholly from eyes indirectly or naturally produced. Recall a woman of a past generation and show her a web of cloth; ask her how it was made, and she will say that the wool or cotton was carded, spun, and woven by hand. When you tell her it was not made by manual labor, that probably no hand has touched the materials throughout the process, it is possible that she might at first regard your statement as tantamount to the assertion that the cloth was made without design. If she did, she would not credit your statement. If you patiently explained to her the theory of carding-machines, spinning-jennies, and power-looms, would her reception of your explanation weaken her conviction that the cloth was the result of design? It is certain that she would believe in design as firmly as before, and that this belief would be attended by a higher conception and reverent admiration of a wisdom, skill, and power greatly beyond anything she had previously conceived possible. Wherefore, we may insist that, for all that yet appears, the argument for design, as presented by the natural theologians, is just as good now, if we accept Darwin's theory, as it was before that theory was promulgated; and that the skeptical juryman, who was about to join the other eleven in a unanimous verdict in favor of design, finds no good excuse for keeping the court longer waiting.[II-1] III NATURAL SELECTION NOT INCONSISTENT WITH NATURAL THEOLOGY (Atlantic Monthly for July, August, and October, 1860, reprinted in 1861) I Novelties are enticing to most people; to us they are simply annoying. We cling to a long-accepted theory, just as we cling to an old suit of clothes. A new theory, like a new pair of breeches (the Atlantic still affects the older type of nether garment), is sure to have hard-fitting places; or, even when no particular fault can be found with the article, it oppresses with a sense of general discomfort. New notions and new styles worry us, till we get well used to them, which is only by slow degrees. Wherefore, in Galileo's time, we might have helped to proscribe, or to burn--had he been stubborn enough to warrant cremation--even the great pioneer of inductive research; although, when we had fairly recovered our composure, and bad leisurely excogitated the matter, we might have come to conclude that the new doctrine was better than the old one, after all, at least for those who had nothing to unlearn. Such being our habitual state of mind, it may well be believed that the perusal of the new book "On the Origin of Species by Means of Natural Selection" left an uncomfortable impression, in spite of its plausible and winning ways. We were not wholly unprepared for it, as many of our contemporaries seem to have been. The scientific reading in which we indulge as a relaxation from severer studies had raised dim forebodings. Investigations about the succession of species in time, and their actual geographical distribution over the earth's surface, were leading up from all sides and in various ways to the question of their origin. Now and then we encountered a sentence, like Prof. Owen's "axiom of the continuous operation of the ordained becoming of living things," which haunted us like an apparition. For, dim as our conception must needs be as to what such oracular and grandiloquent phrases might really mean, we felt confident that they presaged no good to old beliefs. Foreseeing, yet deprecating, the coming time of trouble, we still hoped that, with some repairs and makeshifts, the old views might last out our days. Apres nous le deluge. Still, not to lag behind the rest of the world, we read the book in which the new theory is promulgated. We took it up, like our neighbors, and, as was natural, in a somewhat captious frame of mind. Well, we found no cause of quarrel with the first chapter. Here the author takes us directly to the barn-yard and the kitchen-garden. Like an honorable rural member of our General Court, who sat silent until, near the close of a long session, a bill requiring all swine at large to wear pokes was introduced, when he claimed the privilege of addressing the house, on the proper ground that he had been "brought up among the pigs, and knew all about them"--so we were brought up among cows and cabbages; and the lowing of cattle, the cackle of hens, and the cooing of pigeons, were sounds native and pleasant to our ears. So "Variation under Domestication" dealt with familiar subjects in a natural way, and gently introduced "Variation under Nature," which seemed likely enough. Then follows "Struggle for Existence"--a principle which we experimentally know to be true and cogent--bringing the comfortable assurance, that man, even upon Leviathan Hobbes's theory of society, is no worse than the rest of creation, since all Nature is at war, one species with another, and the nearer kindred the more internecine--bringing in thousandfold confirmation and extension of the Malthusian doctrine that population tends far to outrun means of subsistence throughout the animal and vegetable world, and has to be kept down by sharp preventive checks; so that not more than one of a hundred or a thousand of the individuals whose existence is so wonderfully and so sedulously provided for ever comes to anything, under ordinary circumstances; so the lucky and the strong must prevail, and the weaker and ill-favored must perish; and then follows, as naturally as one sheep follows another, the chapter on "Natural Selection," Darwin's cheval de bataille, which is very much the Napoleonic doctrine that Providence favors the strongest battalions--that, since many more individuals are born than can possibly survive, those individuals and those variations which possess any advantage, however slight, over the rest, are in the long-run sure to survive, to propagate, and to occupy the limited field, to the exclusion or destruction of the weaker brethren. All this we pondered, and could not much object to. In fact, we began to contract a liking for a system which at the outset illustrates the advantages of good breeding, and which makes the most "of every creature's best." Could we "let by-gones be by-gones," and, beginning now, go on improving and diversifying for the future by natural selection, could we even take up the theory at the introduction of the actually existing species, we should be well content; and so, perhaps, would most naturalists be. It is by no means difficult to believe that varieties are incipient or possible species, when we see what trouble naturalists, especially botanists, have to distinguish between them--one regarding as a true species what another regards as a variety; when the progress of knowledge continually increases, rather than diminishes, the number of doubtful instances; and when there is less agreement than ever among naturalists as to what is the basis in Nature upon which our idea of species reposes, or how the word is to be defined. Indeed, when we consider the endless disputes of naturalists and ethnologists over the human races, as to whether they belong to one species or to more, and, if to more, whether to three, or five, or fifty, we can �hardly help fancying that both may be right--or rather, that the uni-humanitarians would have been right many thousand years ago, and the multi-humanitarians will be several thousand years later; while at present the safe thing to say is, that probably there is some truth on both sides. "Natural selection," Darwin remarks, "leads to divergence of character; for the more living beings can be supported on the same area, the more they diverge in structure, habits, and constitution" (a principle which, by-the-way, is paralleled and illustrated by the diversification of human labor); and also leads to much extinction of intermediate or unimproved forms. Now, though this divergence may "steadily tend to increase," yet this is evidently a slow process in Nature, and liable to much counteraction wherever man does not interpose, and so not likely to work much harm for the future. And if natural selection, with artificial to help it, will produce better animals and better men than the present, and fit them better to the conditions of existence, why, let it work, say we, to the top of its bent There is still room enough for improvement. Only let us hope that it always works for good: if not, the divergent lines on Darwin's lithographic diagram of "Transmutation made Easy," ominously show what small deviations from the straight path may come to in the end. The prospect of the future, accordingly, is on the whole pleasant and encouraging. It is only the backward glance, the gaze up the long vista of the past, that reveals anything alarming. Here the lines converge as they recede into the geological ages, and point to conclusions which, upon the theory, are inevitable, but hardly welcome. The very first step backward makes the negro and the Hottentot our blood-relations--not that reason or Scripture objects to that, though pride may. The next suggests a closer association of our ancestors of the olden time with "our poor relations" of the quadrumanous family than we like to acknowledge. Fortunately, however--even if we must account for him scientifically --man with his two feet stands upon a foundation of his own. Intermediate links between the Bimana and the Quadrumana are lacking altogether; so that, put the genealogy of the brutes upon what footing you will, the four-handed races will not serve for our forerunners--at least, not until some monkey, live or fossil, is producible with great-toes, instead of thumbs, upon his nether extremities; or until some lucky geologist turns up the bones of his ancestor and prototype in France or England, who was so busy "napping the chuckie-stanes" and chipping out flint knives and arrow-heads in the time of the drift, very many ages ago--before the British Channel existed, says Lyell [III-1]--and until these men of the olden time are shown to have worn their great-toes in the divergent and thumblike fashion. That would be evidence indeed: but, until some testimony of the sort is produced, we must needs believe in the separate and special creation of man, however it may have been with the lower animals and with plants. No doubt, the full development and symmetry of Darwin's hypothesis strongly suggest the evolution of the human no less than the lower animal races out of some simple primordial animal--that all are equally "lineal descendants of some few beings which lived long before the first bed of the Silurian system was deposited." But, as the author speaks disrespectfully of spontaneous generation, and accepts a supernatural beginning of life on earth, in some form or forms of being which included potentially all that have since existed and are yet to be, he is thereby not warranted to extend his inferences beyond the evidence or the fair probability. There seems as great likelihood that one special origination should be followed by another upon fitting occasion (such as the introduction of man), as that one form should be transmuted into another upon fitting occasion, as, for instance, in the succession of species which differ from each other only in some details. To compare small things with great in a homely illustration: man alters from time to time his instruments or machines, as new circumstances or conditions may require and his wit suggest. Minor alterations and improvements he adds to the machine he possesses; he adapts a new rig or a new rudder to an old boat: this answers to Variation. "Like begets like," being the great rule in Nature, if boats could engender, the variations would doubtless be propagated, like those of domestic cattle. In course of time the old ones would be worn out or wrecked; the best sorts would be chosen for each particular use, and further improved upon; and so the primordial boat be developed into the scow, the skiff, the sloop, and other species of water-craft--the very diversification, as well as the successive improvements, entailing the disappearance of intermediate forms, less adapted to any one particular purpose; wherefore these go slowly out of use, and become extinct species: this is Natural Selection. Now, let a great and important advance be made, like that of steam navigation: here, though the engine might be added to the old vessel, yet the wiser and therefore the actual way is to make a new vessel on a modified plan: this may answer to Specific Creation. Anyhow, the one does not necessarily exclude the other. Variation and natural selection may play their part, and so may specific creation also. Why not? This leads us to ask for the reasons which call for this new theory of transmutation. The beginning of things must needs lie in obscurity, beyond the bounds of proof, though within those of conjecture or of analogical inference. Why not hold fast to the customary view, that all species were directly, instead of indirectly, created after their respective kinds, as we now behold them--and that in a manner which, passing our comprehension, we intuitively refer to the supernatural? Why this continual striving after "the unattained and dim?" why these anxious endeavors, especially of late years, by naturalists and philosophers of various schools and different tendencies, to penetrate what one of them calls "that mystery of mysteries," the origin of species? To this, in general, sufficient answer may be found in the activity of the human intellect, "the delirious yet divine desire to know," stimulated as it has been by its own success in unveiling the laws and processes of inorganic Nature; in the fact that the principal triumphs of our age in physical science have consisted in tracing connections where none were known before, in reducing heterogeneous phenomena to a common cause or origin, in a manner quite analogous to that of the reduction of supposed independently originated species to a common ultimate origin--thus, and in various other ways, largely and legitimately extending the domain of secondary causes. Surely the scientific mind of an age which contemplates the solar system as evolved from a common revolving fluid mass--which, through experimental research, has come to regard light, heat, electricity, magnetism, chemical affinity, and mechanical power as varieties or derivative and convertible forms of one force, instead of independent species--which has brought the so-called elementary kinds of matter, such as the metals, into kindred groups, and pertinently raised the question, whether the members of each group may not be mere varieties of one species--and which speculates steadily in the direction of the ultimate unity of matter, of a sort of prototype or simple element which may be to the ordinary species of matter what the Protozoa or what the component cells of an organism are to the higher sorts of animals and plants--the mind of such an age cannot be expected to let the old belief about species pass unquestioned. It will raise the question, how the diverse sorts of plants and animals came to be as they are and where they are and will allow that the whole inquiry transcends its powers only when all endeavors have failed Granting the origin to be super natural or miraculous even, will not arrest the inquiry All real origination the philosophers will say, is supernatural, their very question is, whether we have yet gone back to the origin and can affirm that the present forms of plants and animals are the primordial, the miraculously created ones. And, even if they admit that, they will still inquire into the order of the phenomena, into the form of the miracle You might as well expect the child to grow up content with what it is told about the advent of its infant brother Indeed, to learn that the new comer is the gift of God, far from lulling inquiry, only stimulates speculation as to how the precious gift was bestowed That questioning child is father to the man--is philosopher in short-clothes. Since, then questions about the origin of species will be raised, and have been raised--and since the theorizings, however different in particulars, all proceed upon the notion that one species of plant or animal is somehow derived from another, that the different sorts which now flourish are lineal (or unlineal) descendants of other and earlier sorts--it now concerns us to ask, What are the grounds in Nature, the admitted facts, which suggest hypotheses of derivation in some :shape or other? Reasons there must be, and plausible ones, for the persistent recurrence of theories upon this genetic basis. A study of Darwin's book, and a general glance at the present state of the natural sciences, enable us to gather the following as among the most suggestive and influential. We can only enumerate them here, without much indication of their particular bearing. There is-- 1. The general fact of variability, and the general tendency of the variety to propagate its like--the patent facts that all species vary more or less; that domesticated plants and animals, being in conditions favorable to the production and preservation of varieties, are apt to vary widely; and that, by interbreeding, any variety may be fixed into a race, that is, into a variety which comes true from seed. Many such races, it is allowed, differ from each other in structure and appearance as widely as do many admitted species; and it is practically very difficult, even impossible, to draw a clear line between races and species. Witness the human races, for instance. Wild species also vary, perhaps about as widely as those of domestication, though in different ways. Some of them apparently vary little, others moderately, others immoderately, to the great bewilderment of systematic botanists and zoologists, and increasing disagreement as to whether various forms shall be held to be original species or strong varieties. Moreover, the degree to which the descendants of the same stock, varying in different directions, may at length diverge, is unknown. All we know is, that varieties are themselves variable, and that very diverse forms have been educed from one stock. 2. Species of the same genus are not distinguished from each other by equal amounts of difference. There is diversity in this respect analogous to that of the varieties of a polymorphous species, some of them slight, others extreme. And in large genera the unequal resemblance shows itself in the clustering of the species around several types or central species, like satellites around their respective planets. Obviously suggestive this of the hypothesis that they were satellites, not thrown off by revolution, like the moons of Jupiter, Saturn, and our own solitary moon, but gradually and peacefully detached by divergent variation. That such closely-related species may be only varieties of higher grade, earlier origin, or more favored evolution, is not a very violent supposition. Anyhow, it was a supposition sure to be made. 3. The actual geographical distribution of species upon the earth's surface tends to suggest the same notion. For, as a general thing, all or most of the species of a peculiar genus or other type are grouped in the same country, or occupy continuous, proximate, or accessible areas. So well does this rule hold, so general is the implication that kindred species are or were associated geographically, that most trustworthy naturalists, quite free from hypotheses of transmutation, are constantly inferring former geographical continuity between parts of the world now widely disjoined, in order to account thereby for certain generic similarities among their inhabitants; just as philologists infer former connection of races, and a parent language, to account for generic similarities among existing languages. Yet no scientific explanation has been offered to account for the geographical association of kindred species, except the hypothesis of a common origin. 4. Here the fact of the antiquity of creation, and in particular of the present kinds of the earth's inhabitants, or of a large part of them, comes in to rebut the objection that there has not been time enough for any marked diversification of living things through divergent variation--not time enough for varieties to have diverged into what we call species. So long as the existing species of plants and animals were thought to have originated a few thousand years ago, and without predecessors, there was no room for a theory of derivation of one sort from another, nor time enough even to account for the establishment of the races which are generally believed to have diverged from a common stock. Not so much that five or six thousand years was a short allowance for this; but because some of our familiar domesticated varieties of grain, of fowls, and of other animals, were pictured and mummified by the old Egyptians more than half that number of years ago, if not earlier. Indeed, perhaps the strongest argument for the original plurality of human species was drawn from the identification of some of the present races of men upon these early historical monuments and records. But this very extension of the current chronology, if we may rely upon the archaeologists, removes the difficulty by opening up a longer vista. So does the discovery in Europe of remains and implements of prehistoric races of men, to whom the use of metals was unknown--men of the stone age, as the Scandinavian archaeologists designate them. And now, "axes and knives of flint, evidently wrought by human skill, are found in beds of the drift at Amiens (also in other places, both in France and England), associated with the bones of extinct species of animals." These implements, indeed, were noticed twenty years ago; at a place in Suffolk they have been exhumed from time to time for more than a century; but the full confirmation, the recognition of the age of the deposit in which the implements occur, their abundance, and the appreciation of their bearings upon most interesting questions, belong to the present time. To complete the connection of these primitive people with the fossil ages, the French geologists, we are told, have now "found these axes in Picardy associated with remains of Elephas primigenius, Rhinoceros tichorhinus, Equus fossilis, and an extinct species of Bos."[III-2] In plain language, these workers in flint lived in the time of the mammoth, of a rhinoceros now extinct, and along with horses and cattle unlike any now existing--specifically different, as naturalists say, from those with which man is now associated. Their connection with existing human races may perhaps be traced through the intervening people of the stone age, who were succeeded by the people of the bronze age, and these by workers in iron.[III-3] Now, various evidence carries back the existence of many of the present lower species of animals, and probably of a larger number of plants, to the same drift period. All agree that this was very many thousand years ago. Agassiz tells us that the same species of polyps which are now building coral walls around the present peninsula of Florida actually made that peninsula, and have been building there for many thousand centuries. 5. The overlapping of existing and extinct species, and the seemingly gradual transition of the life of the drift period into that of the present, may be turned to the same account. Mammoths, mastodons, and Irish elks, now extinct, must have lived down to human, if not almost to historic times. Perhaps the last dodo did not long outlive his huge New Zealand kindred. The aurochs, once the companion of mammoths, still survives, but owes his present and precarious existence to man's care. Now, nothing that we know of forbids the hypothesis that some new species have been independently and supernaturally created within the period which other species have survived. Some may even believe that man was created in the days of the mammoth, became extinct, and was recreated at a later date. But why not say the same of the aurochs, contemporary both of the old man and of the new? Still it is more natural, if not inevitable, to infer that, if the aurochs of that olden time were the ancestors of the aurochs of the Lithuanian forests, so likewise were the men of that age the ancestors of the present human races. Then, whoever concludes that these primitive makers of rude flint axes and knives were the ancestors of the better workmen of the succeeding stone age, and these again of the succeeding artificers in brass and iron, will also be likely to suppose that the Equus and Bos of that time, different though they be, were the remote progenitors of our own horses and cattle. In all candor we must at least concede that such considerations suggest a genetic descent from the drift period down to the present, and allow time enough--if time is of any account-- for variation and natural selection to work out some appreciable results in the way of divergence into races, or even into so-called species. Whatever might have been thought, when geological time was supposed to be separated from the present era by a clear line, it is now certain that a gradual replacement of old forms by new ones is strongly suggestive of some mode of origination which may still be operative. When species, like individuals, were found to die out one by one, and apparently to come in one by one, a theory for what Owen sonorously calls "the continuous operation of the ordained becoming of living things" could not be far off. That all such theories should take the form of a derivation of the new from the old seems to be inevitable, perhaps from our inability to conceive of any other line of secondary causes in this connection. Owen himself is apparently in travail with some transmutation theory of his own conceiving, which may yet see the light, although Darwin's came first to the birth. Different as the two theories will probably be, they cannot fail to exhibit that fundamental resemblance in this respect which betokens a community of origin, a common foundation on the general facts and the obvious suggestions of modern science. Indeed--to turn the point of a pungent simile directed against Darwin--the difference between the Darwinian and the Owenian hypotheses may, after all, be only that between homoeopathic and heroic doses of the same drug. If theories of derivation could only stop here, content with explaining the diversification and succession of species between the teritiary period and the present time, through natural agencies or secondary causes still in operation, we fancy they would not be generally or violently objected to by the savants of the present day. But it is hard, if not impossible, to find a stopping-place. Some of the facts or accepted conclusions already referred to, and several others, of a more general character, which must be taken into the account, impel the theory onward with accumulated force. Vires (not to say virus) acquirit eundo. The theory hitches on wonderfully well to Lyell's uniformitarian theory in geology--that the thing that has been is the thing that is and shall be--that the natural operations now going on will account for all geological changes in a quiet and easy way, only give them time enough, so connecting the present and the proximate with the farthest past by almost imperceptible gradations--a view which finds large and increasing, if not general, acceptance in physical geology, and of which Darwin's theory is the natural complement. So the Darwinian theory, once getting a foothold, marches; boldly on, follows the supposed near ancestors of our present species farther and yet farther back into the dim past, and ends with an analogical inference which "makes the whole world kin." As we said at the beginning, this upshot discomposes us. Several features of the theory have an uncanny look. They may prove to be innocent: but their first aspect is suspicious, and high authorities pronounce the whole thing to be positively mischievous. In this dilemma we are going to take advice. Following the bent of our prejudices, and hoping to fortify these by new and strong arguments, we are going now to read the principal reviews which undertake to demolish the theory--with what result our readers shall be duly informed. II "I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists entertain, and which I formerly entertained, namely, that each species has been independently created, is erroneous. I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species. Furthermore, I am convinced that Natural Selection has been the main, but not exclusive, means of modification." This is the kernel of the new theory, the Darwinian creed, as recited at the close of the introduction to the remarkable book under consideration. The questions, "What will he do with it?" and "How far will he carry it?" the author answers at the close of the volume: "I cannot doubt that the theory of descent with modification embraces all the members of the same class." Furthermore, "I believe that all animals have descended from at most only four or five progenitors, and plants from an equal or lesser number." Seeing that analogy as strongly suggests a further step in the same direction, while he protests that "analogy may be a deceitful guide," yet he follows its inexorable leading to the inference that-- "Probably all the organic beings which have ever lived on this ear have descended from some one primordial form, into which life was first breathed."[III-4] In the first extract we have the thin end of the wedge driven a little way; in the last, the wedge driven home. We have already sketched some of the reasons suggestive of such a theory of derivation of species, reasons which gave it plausibility, and even no small probability, as applied to our actual world and to changes occurring since the latest tertiary period. We are well pleased at this moment to find that the conclusions we were arriving at in this respect are sustained by the very high authority and impartial judgment of Pictet, the Swiss paleontologist. In his review of Darwin's book[III-5] -- the fairest and most admirable opposing one that has appeared--he freely accepts that ensemble of natural operations which Darwin impersonates under the now familiar name of Natural Selection, allows that the exposition throughout the first chapters seems "a la fois prudent et fort," and is disposed to accept the whole argument in its foundations, that is, so far as it relates to what is now going on, or has taken place in the present geological period--which period he carries back through the diluvial epoch to the borders of the tertiary.[III-6] Pictet accordingly admits that the theory will very well account for the origination by divergence of nearly-related species, whether within the present period or in remoter geological times; a very natural view for him to take, since he appears to have reached and published, several years ago, the pregnant conclusion that there most probably was some material connection between the closely-related species of two successive faunas, and that the numerous close species, whose limits are so difficult to determine, were not all created distinct and independent. But while thus accepting, or ready to accept, the basis of Darwin's theory, and all its legitimate direct inferences, he rejects the ultimate conclusions, brings some weighty arguments to bear against them, and is evidently convinced that he can draw a clear line between the sound inferences, which he favors, and the unsound or unwarranted theoretical deductions, which he rejects. We hope he can. This raises the question, Why does Darwin press his theory to these extreme conclusions? Why do all hypotheses of derivation converge so inevitably to one ultimate point? Having already considered some of the reasons which suggest or support the theory at its outset--which may carry it as far as such sound and experienced naturalists as Pictet allow that it may be true--perhaps as far as Darwin himself unfolds it in the introductory proposition cited at the beginning of this article--we may now inquire after the motives which impel the theorist so much farther. Here proofs, in the proper sense of the word, are not to be had. We are beyond the region of demonstration, and have only probabilities to consider. What are these probabilities? What work will this hypothesis do to establish a claim to be adopted in its completeness? Why should a theory which may plausibly enough account for the diversification of the species of each special type or genus be expanded into a general system for the origination or successive diversification of all species, and all special types or forms, from four or five remote primordial forms, or perhaps from one? We accept the theory of gravitation because it explains all the facts we know, and bears all the tests that we can put it to. We incline to accept the nebular hypothesis, for similar reasons; not because it is proved--thus far it is incapable of proof--but because it is a natural theoretical deduction from accepted physical laws, is thoroughly congruous with the facts, and because its assumption serves to connect and harmonize these into one probable and consistent whole. Can the derivative hypothesis be maintained and carried out into a system on similar grounds? If so, however unproved, it would appear to be a tenable hypothesis, which is all that its author ought now to claim. Such hypotheses as, from the conditions of the case, can neither be proved nor disproved by direct evidence or experiment, are to be tested only indirectly, and therefore imperfectly, by trying their power to harmonize the known facts, and to account for what is otherwise unaccountable. So the question comes to this: What will an hypothesis of the derivation of species explain which the opposing view leaves unexplained? Questions these which ought to be entertained before we take up the arguments which have been advanced against this theory. We can barely glance at some of the considerations which Darwin adduces, or will be sure to adduce in the future and fuller exposition which is promised. To display them in such wise as to indoctrinate the unscientific reader would require a volume. Merely to refer to them in the most general terms would suffice for those familiar with scientific matters, but would scarcely enlighten those who are not. Wherefore let these trust the impartial Pictet, who freely admits that, "in the absence of sufficient direct proofs to justify the possibility of his hypothesis, Mr. Darwin relies upon indirect proofs, the bearing of which is real and incontestable;" who concedes that "his theory accords very well with the great facts of comparative anatomy and zoology--comes in admirably to explain unity of composition of organisms, also to explain rudimentary and representative organs, and the natural series of genera and species--equally corresponds with many paleontological data--agrees well with the specific resemblances which exist between two successive faunas, with the parallelism which is sometimes observed between the series of paleontological succession and of embryonal development," etc.; and finally, although he does not accept the theory in these results, he allows that "it appears to offer the best means of explaining the manner in which organized beings were produced in epochs anterior to our own." What more than this could be said for such an hypothesis? Here, probably, is its charm, and its strong hold upon the speculative mind. Unproven though it be, and cumbered prima facie with cumulative improbabilities as it proceeds, yet it singularly accords with great classes of facts otherwise insulated and enigmatic, and explains many things which are thus far utterly inexplicable upon any other scientific assumption. We have said that Darwin's hypothesis is the natural complement to Lyell's uniformitarian theory in physical geology. It is for the organic world what that is for the inorganic; and the accepters of the latter stand in a position from which to regard the former in the most favorable light. Wherefore the rumor that the cautious Lyell himself has adopted the Darwinian hypothesis need not surprise us. The two views are made for each other, and, like the two counterpart pictures for the stereoscope, when brought together, combine into one apparently solid whole. If we allow, with Pictet, that Darwin's theory will very well serve for all that concerns the present epoch of the world's history--an epoch in which this renowned paleontologist includes the diluvial or quaternary period--then Darwin's first and foremost need in his onward course is a practicable road from this into and through the tertiary period, the intervening region between the comparatively near and the far remote past. Here Lyell's doctrine paves the way, by showing that in the physical geology there is no general or absolute break between the two, probably no greater between the latest tertiary and the quaternary period than between the latter and the present time. So far, the Lyellian view is, we suppose, generally concurred in. It is largely admitted that numerous tertiary species have continued down into the quaternary, and many of them to the present time. A goodly percentage of the earlier and nearly half of the later tertiary mollusca, according to Des Hayes, Lye!!, and, if we mistake not, Bronn, still live. This identification, however, is now questioned by a naturalist of the very highest authority. But, in its bearings on the new theory, the point here turns not upon absolute identity so much as upon close resemblance. For those who, with Agassiz, doubt the specific identity in any of these cases, and those who say, with Pictet, that "the later tertiary deposits contain in general the debris of species very nearly related to those which still exist, belonging to the same genera, but specifically different," may also agree with Pictet, that the nearly-related species of successive faunas must or may have had "a material connection." But the only material connection that we have an idea of in such a case is a genealogical one. And the supposition of a genealogical connection is surely not unnatural in such cases--is demonstrably the natural one as respects all those tertiary species which experienced naturalists have pronounced to be identical with existing ones, but which others now deem distinct For to identify the two is the same thing as to conclude the one to be the ancestor of the other No doubt there are differences between the tertiary and the present individuals, differences equally noticed by both classes of naturalists, but differently estimated By the one these are deemed quite compatible, by the other incompatible, with community of origin But who can tell us what amount of difference is compatible with community of origin? This is the very question at issue, and one to be settled by observation alone Who would have thought that the peach and the nectarine came from one stock? But, this being proved is it now very improbable that both were derived from the almond, or from some common amygdaline progenitor? Who would have thought that the cabbage, cauliflower, broccoli kale, and kohlrabi are derivatives of one species, and rape or colza, turnip, and probably ruta-baga, of another species? And who that is convinced of this can long undoubtingly hold the original distinctness of turnips from cabbages as an article of faith? On scientific grounds may not a primordial cabbage or rape be assumed as the ancestor of all the cabbage races, on much the same ground that we assume a common ancestry for the diversified human races? If all Our breeds of cattle came from one stock why not this stock from the auroch, which has had all the time between the diluvial and the historic periods in which to set off a variation perhaps no greater than the difference between some sorts of domestic cattle? That considerable differences are often discernible between tertiary individuals and their supposed descendants of the present day affords no argument against Darwin's theory, as has been rashly thought, but is decidedly in its favor. If the identification were so perfect that no more differences were observable between the tertiary and the recent shells than between various individuals of either, then Darwin's opponents, who argue the immutability of species from the ibises and cats preserved by the ancient Egyptians being just like those of the present day, could triumphantly add a few hundred thousand years more to the length of the experiment and to the force of their argument. As the facts stand, it appears that, while some tertiary forms are essentially undistinguishable from existing ones, others are the same with a difference, which is judged not to be specific or aboriginal; and yet others show somewhat greater differences, such as are scientifically expressed by calling them marked varieties, or else doubtful species; while others, differing a little more, are confidently termed distinct, but nearly-related species. Now, is not all this a question of degree, of mere gradation of difference? And is it at all likely that these several gradations came to be established in two totally different ways--some of them (though naturalists can't agree which) through natural variation, or other secondary cause, and some by original creation, without secondary cause? We have seen that the judicious Pictet answers such questions as Darwin would have him do, in affirming that, in all probability, the nearly-related species of two successive faunas were materially connected, and that contemporaneous species, similarly resembling each other, were not all created so, but have become so. This is equivalent to saying that species (using the term as all naturalists do, and must continue to employ the word) have only a relative, not an absolute fixity; that differences fully equivalent to what are held to be specific may arise in the course of time, so that one species may at length be naturally replaced by another species a good deal like it, or may be diversified into two, three, or more species, or forms as different as species. This concedes all that Darwin has a right to ask, all that he can directly infer from evidence. We must add that it affords a locus standi, more or less tenable, for inferring more. Here another geological consideration comes in to help on this inference. The species of the later tertiary period for the most part not only resembled those of our days--many of them so closely as to suggest an absolute continuity--but also occupied in general the same regions that their relatives occupy now. The same may be said, though less specially, of the earlier tertiary and of the later secondary; but there is less and less localization of forms as we recede, yet some localization even in palaeozoic times. While in the secondary period one is struck with the similarity of forms and the identity of many of the species which flourished apparently at the same time in all or in the most widely-separated parts of the world, in the tertiary epoch, on the contrary, along with the increasing specialization of climates and their approximation to the present state, we find abundant evidence of increasing localization of orders, genera and species, and this localization strikingly accords with the present geographical distribution of the same groups of species Where the imputed forefathers lived their relatives and supposed descendants now flourish All the actual classes of the animal and vegetable kingdoms were represented in the tertiary faunas and floras and in nearly the same proportions and the same diversities as at present The faunas of what is now Europe, Asia America and Australia, differed from each other much as they now differ: in fact--according to Adolphe Brongniart, whose statements we here condense[III-7]--the inhabitants of these different regions appear for the most part to have acquired, before the close of the tertiary period, the characters which essentially distinguish their existing faunas. The Eastern Continent had then, as now, its great pachyderms, elephants, rhinoceros, hippopotamus; South America, its armadillos, sloths, and anteaters; Australia, a crowd of marsupials; and the very strange birds of New Zealand had predecessors of similar strangeness. Everywhere the same geographical distribution as now, with a difference in the particular area, as respects the northern portion of the continents, answering to a warmer climate then than ours, such as allowed species of hippopotamus, rhinoceros, and elephant, to range even to the regions now inhabited by the reindeer and the musk-ox, and with the serious disturbing intervention of the glacial period within a comparatively recent time. Let it be noted also that those tertiary species which have continued with little change down to our days are the marine animals of the lower grades, especially mollusca. Their low organization, moderate sensibility, and the simple conditions of an existence in a medium like the ocean, not subject to great variation and incapable of sudden change, may well account for their continuance; while, on the other hand, the more intense, however gradual, climatic vicissitudes on land, which have driven all tropical and subtropical forms out of the higher latitudes and assigned to them their actual limits, would be almost sure to extinguish such huge and unwieldy animals as mastodons, mammoths, and the like, whose power of enduring altered circumstances must have been small. This general replacement of the tertiary species of a country by others so much like them is a noteworthy fact. The hypothesis of the independent creation of all species, irrespective of their antecedents, leaves this fact just as mysterious as is creation itself; that of derivation undertakes to account for it. Whether it satisfactorily does so or not, it must be allowed that the facts well accord with that hypothesis. The same may be said of another conclusion, namely, that the geological succession of animals and plants appears to correspond in a general way with their relative standing or rank in a natural system of classification. It seems clear that, though no one of the grand types of the animal kingdom can be traced back farther than the rest, yet the lower classes long preceded the higher; that there has been on the whole a steady progression within each class and order; and that the highest plants and animals have appeared only in relatively modern times. It is only, however, in a broad sense that this generalization is now thought to hold good. It encounters many apparent exceptions, and sundry real ones. So far as the rule holds, all is as it should be upon an hypothesis of derivation. The rule has its exceptions. But, curiously enough, the most striking class of exceptions, if such they be, seems to us even more favorable to the doctrine of derivation than is the general rule of a pure and simple ascending gradation. We refer to what Agassiz calls prophetic and synthetic types; for which the former name may suffice, as the difference between the two is evanescent. "It has been noticed," writes our great zoologist, "that certain types, which are frequently prominent among the representatives of past ages, combine in their structure peculiarities which at later periods are only observed separately in different, distinct types. Sauroid fishes before reptiles, Pterodactyles before birds, Ichthyosauri before dolphins, etc. There are entire families, of nearly every class of animals, which in the state of their perfect development exemplify such prophetic relations. The sauroid fishes of the past geological ages are an example of this kind These fishes which preceded the appearance of reptiles present a combination of ichthyic and reptilian characters not to be found in the true members of this class, which form its bulk at present. The Pterodactyles, which preceded the class of birds, and the Ichthyosauri, which preceded the Cetacea, are other examples of such prophetic types."--(Agassiz, "Contributions, Essay on Classification," p. 117.) Now, these reptile-like fishes, of which gar-pikes are the living representatives, though of earlier appearance, are admittedly of higher rank than common fishes. They dominated until reptiles appeared, when they mostly gave place to (or, as the derivationists will insist, were resolved by divergent variation and natural selection into) common fishes, destitute of reptilian characters, and saurian reptiles--the intermediate grades, which, according to a familiar piscine saying, are "neither fish, flesh, nor good red-herring," being eliminated and extinguished by natural consequence of the struggle for existence which Darwin so aptly portrays. And so, perhaps, of the other prophetic types. Here type and antitype correspond. If these are true prophecies, we need not wonder that some who read them in Agassiz's book will read their fulfillment in Darwin's. Note also, in this connection, that along with a wonderful persistence of type, with change of species, genera, orders, etc., from formation to formation, no species and no higher group which has once unequivocally died out ever afterward reappears. Why is this, but that the link of generation has been sundered? Why, on the hypothesis of independent originations, were not failing species recreated, either identically or with a difference, in regions eminently adapted to their well-being? To take a striking case. That no part of the world now offers more suitable conditions for wild horses and cattle than the pampas and other plains of South America, is shown by the facility with which they have there run wild and enormously multiplied, since introduced from the Old World not long ago. There was no wild American stock. Yet in the times of the mastodon and megatherium, at the dawn of the present period, wild-horses--certainly very much like the existing horse--roamed over those plains in abundance. On the principle of original and direct created adaptation of species to climate and other conditions, why were they not reproduced, when, after the colder intervening era, those regions became again eminently adapted to such animals? Why, but because, by their complete extinction in South America, the line of descent was there utterly broken? Upon the ordinary hypothesis, there is no scientific explanation possible of this series of facts, and of many others like them. Upon the new hypothesis, "the succession of the same types of structure within the same areas during the later geological periods ceases to be mysterious, and is simply explained by inheritance." Their cessation is failure of issue. Along with these considerations the fact (alluded to on page 98) should be remembered that, as a general thing, related species of the present age are geographically associated. The larger part of the plants, and still more of the animals, of each separate country are peculiar to it; and, as most species now flourish over the graves of their by-gone relatives of former ages, so they now dwell among or accessibly near their kindred species. Here also comes in that general "parallelism between the order of succession of animals and plants in geological times, and the gradation among their living representatives" from low to highly organized, from simple and general to complex and specialized forms; also "the parallelism between the order of succession of animals in geological times and the changes their living representatives undergo during their embryological growth," as if the world were one prolonged gestation. Modern science has much insisted on this parallelism, and to a certain extent is allowed to have made it out. All these things, which conspire to prove that the ancient and the recent forms of life "are somehow intimately connected together in one grand system," equally conspire to suggest that the connection is one similar or analogous to generation. Surely no naturalist can be blamed for entering somewhat confidently upon a field of speculative inquiry which here opens so invitingly; nor need former premature endeavors and failures utterly dishearten him. All these things, it may naturally be said, go to explain the order, not the mode, of the incoming of species. But they all do tend to bring out the generalization expressed by Mr. Wallace in the formula that "every species has come into existence coincident both in time and space with preexisting closely-allied species." Not, however, that this is proved even of existing species as a matter of general fact. It is obviously impossible to prove anything of the kind. But we must concede that the known facts strongly suggest such an inference. And--since species are only congeries of individuals, since every individual came into existence in consequence of preexisting individuals of the same sort, so leading up to the individuals with which the species began, and since the only material sequence we know of among plants and animals is that from parent to progeny--the presumption becomes exceedingly strong that the connection of the incoming with the preexisting species is a genealogical one. Here, however, all depends upon the probability that Mr. Wallace's inference is really true. Certainly it is not yet generally accepted; but a strong current is setting toward its acceptance. So long as universal cataclysms were in vogue, and all life upon the earth was thought to have been suddenly destroyed and renewed many times in succession, such a view could not be thought of. So the equivalent view maintained by Agassiz, and formerly, we believe, by D'Orbigny, that irrespectively of general and sudden catastrophes, or any known adequate physical cause, there has been a total depopulation at the close of each geological period or formation, say forty or fifty times or more, followed by as many independent great acts of creation, at which alone have species been originated, and at each of which a vegetable and an animal kingdom were produced entire and complete, full-fledged, as flourishing, as wide-spread, and populous, as varied and mutually adapted from the beginning as ever afterward--such a view, of course, supersedes all material connection between successive species, and removes even the association and geographical range of species entirely out of the domain of physical causes and of natural science. This is the extreme opposite of Wallace's and Darwin's view, and is quite as hypothetical. The nearly universal opinion, if we rightly gather it, manifestly is, that the replacement of the species of successive formations was not complete and simultaneous, but partial and successive; and that along the course of each epoch some species probably were introduced, and some, doubtless, became extinct. If all since the tertiary belongs to our present epoch, this is certainly true of it: if to two or more epochs, then the hypothesis of a total change is not true of them. Geology makes huge demands upon time; and we regret to find that it has exhausted ours--that what we meant for the briefest and most general sketch of some geological considerations in favor of Darwin's hypothesis has so extended as to leave no room for considering "the great facts of comparative anatomy and zoology" with which Darwin's theory "very well accords," nor for indicating how "it admirably serves for explaining the unity of composition of all organisms, the existence of representative and rudimentary organs, and the natural series which genera and species compose." Suffice it to say that these are the real strongholds of the new system on its theoretical side; that it goes far toward explaining both the physiological and the structural gradations and relations between the two kingdoms, and the arrangement of all their forms in groups subordinate to groups, all within a few great types; that it reads the riddle of abortive organs and of morphological conformity, of which no other theory has ever offered a scientific explanation, and supplies a ground for harmonizing the two fundamental ideas which naturalists and philosophers conceive to have ruled the organic world, though they could not reconcile them; namely, Adaptation to Purpose and Conditions of Existence, and Unity of Type. To reconcile these two undeniable principles is the capital problem in the philosophy of natural history; and the hypothesis which consistently does so thereby secures a great advantage. We all know that the arm and hand of a monkey, the foreleg and foot of a dog and of a horse, the wing of a bat, and the fin of a porpoise, are fundamentally identical; that the long neck of the giraffe has the same and no more bones than the short one of the elephant; that the eggs of Surinam frogs hatch into tadpoles with as good tails for swimming as any of their kindred, although as tadpoles they never enter the water; that the Guinea-pig is furnished with incisor teeth which it never uses, as it sheds them before birth; that embryos of mammals and birds have branchial slits and arteries running in loops, in imitation or reminiscence of the arrangement which is permanent in fishes; and that thousands of animals and plants have rudimentary organs which, at least in numerous cases, are wholly useless to their possessors, etc., etc. Upon a derivative theory this morphological conformity is explained by community of descent; and it has not been explained in any other way. Naturalists are constantly speaking of "related species," of the "affinity" of a genus or other group, and of "family resemblance"--vaguely conscious that these terms of kinship are something more than mere metaphors, but unaware of the grounds of their aptness. Mr. Darwin assures them that they have been talking derivative doctrine all their lives--as M. Jourdain talked prose--without knowing it. If it is difficult and in many cases practically impossible to fix the limits of species, it is still more so to fix those of genera; and those of tribes and families are still less susceptible of exact natural circumscription. Intermediate forms occur, connecting one group with another in a manner sadly perplexing to systematists, except to those who have ceased to expect absolute limitations in Nature. All this blending could hardly fail to suggest a former material connection among allied forms, such as that which the hypothesis of derivation demands. Here it would not be amiss to consider the general principle of gradation throughout organic Nature--a principle which answers in a general way to the Law of Continuity in the inorganic world, or rather is so analogous to it that both may fairly be expressed by the Leibnitzian axiom, Natura non agit saltatim. As an axiom or philosophical principle, used to test modal laws or hypotheses, this in strictness belongs only to physics. In the investigation of Nature at large, at least in the organic world, nobody would undertake to apply this principle as a test of the validity of any theory or supposed law. But naturalists of enlarged views will not fail to infer the principle from the phenomena they investigate--to perceive that the rule holds, under due qualifications and altered forms, throughout the realm of Nature; although we do not suppose that Nature in the organic world makes no distinct steps, but only short and serial steps--not infinitely fine gradations, but no long leaps, or few of them. To glance at a few illustrations out of many that present themselves. It would be thought that the distinction between the two organic kingdoms was broad and absolute. Plants and animals belong to two very different categories, fulfill opposite offices and, as to the mass of them are so unlike that the difficulty of the ordinary observer would be to find points of comparison Without entering into details which would fill an article, we may safely say that the difficulty with the naturalist is all the other way--that all these broad differences vanish one by one as we approach the lower confines of the two kingdoms, and that no absolute distinction whatever is now known between them. It is quite possible that the same organism may be both vegetable and animal, or may be first the one and then the other. If some organisms may be said to be at first vegetables and then animals, others, like the spores and other reproductive bodies of many of the lower Algae, may equally claim to have first a characteristically animal, and then an unequivocally vegetable existence. Nor is the gradation restricted to these simple organisms. It appears in general functions, as in that of reproduction, which is reducible to the same formula in both kingdoms, while it exhibits close approximations in the lower forms; also in a common or similar ground of sensibility in the lowest forms of both, a common faculty of effecting movements tending to a determinate end, traces of which pervade the vegetable kingdom--while, on the other hand, this indefinable principle, this vegetable "Animula vagula, blandula, Hospes comesque corporis," graduates into the higher sensitiveness of the lower class of animals. Nor need we hesitate to recognize the fine gradations from simple sensitiveness and volition to the higher instinctive and to the other psychical manifestations of the higher brute animals. The gradation is undoubted, however we may explain it. Again, propagation is of one mode in the higher animals, of two in all plants; but vegetative propagation, by budding or offshoots, extends through the lower grades of animals. In both kingdoms there may be separation of the offshoots, or indifference in this respect, or continued and organic union with the parent stock; and this either with essential independence of the offshoots, or with a subordination of these to a common whole; or finally with such subordination and amalgamation, along with specialization of function, that the same parts, which in other cases can be regarded only as progeny, in these become only members of an individual. This leads to the question of individuality, a subject quite too large and too recondite for present discussion. The conclusion of the whole matter, however, is, that individuality--that very ground of being as distinguished from thing--is not attained in Nature at one leap. If anywhere truly exemplified in plants, it is only in the lowest and simplest, where the being is a structural unit, a single cell, member-less and organless, though organic--the same thing as those cells of which all the more complex plants are built up, and with which every plant and (structurally) every animal began its development. In the ascending gradation of the vegetable kingdom individuality is, so to say, striven after, but never attained; in the lower animals it is striven after with greater though incomplete success; it is realized only in animals of so high a rank that vegetative multiplication or offshoots are out of the question, where all parts are strictly members and nothing else, and all subordinated to a common nervous centre--is fully realized only in a conscious person. So, also, the broad distinction between reproduction by seeds or ova and propagation by buds, though perfect in some of the lowest forms of life, becomes evanescent in others; and even the most absolute law we know in the physiology of genuine reproduction--that of sexual cooperation--has its exceptions in both kingdoms in parthenogenesis, to which in the vegetable kingdom a most curious and intimate series of gradations leads. In plants, likewise, a long and finely graduated series of transitions leads from bisexual to unisexual blossoms; and so in various other respects. Everywhere we may perceive that Nature secures her ends, and makes her distinctions on the whole manifest and real but everywhere without abrupt breaks We need not wonder therefore that gradations between species and varieties should occur; the more so, since genera, tribes, and other groups into which the naturalist collocates species, are far from being always absolutely limited in Nature, though they are necessarily represented to be so in systems. >From the necessity of the case, the classifications of the naturalist abruptly define where Nature more or less blends. Our systems are nothing, if not definite. They express differences, and some of the coarser gradations. But this evinces not their perfection, but their imperfection. Even the best of them are to the system of Nature what consecutive patches of the seven colors are to the rainbow. Now the principle of gradation throughout organic Nature may, of course, be interpreted upon other assumptions than those of Darwin's hypothesis--certainly upon quite other than those of a materialistic philosophy, with which we ourselves have no sympathy. Still we conceive it not only possible, but probable, that this gradation, as it has its natural ground, may yet have its scientific explanation. In any case, there is no need to deny that the general facts correspond well with an hypothesis like Darwin's, which is built upon fine gradations. We have contemplated quite long enough the general presumptions in favor of an hypothesis of the derivation of species. We cannot forget, however, while for the moment we overlook, the formidable difficulties which all hypotheses of this class have to encounter, and the serious implications which they seem to involve. We feel, moreover, that Darwin's particular hypothesis is exposed to some special objections. It requires no small strength of nerve steadily to conceive, not only of the diversification, but of the formation of the organs of an animal through cumulative variation and natural selection. Think of such an organ as the eye, that most perfect of optical instruments, as so produced in the lower animals and perfected in the higher! A friend of ours, who accepts the new doctrine, confesses that for a long while a cold chill came over him whenever he thought of the eye. He has at length got over that stage of the complaint, and is now in the fever of belief, perchance to be succeeded by the sweating stage, during which sundry peccant humors may be eliminated from the system. For ourselves, we dread the chill, and have some misgivings about the consequences of the reaction. We find ourselves in the "singular position" acknowledged by Pictet--that is, confronted with a theory which, although it can really explain much, seems inadequate to the heavy task it so boldly assumes, but which, nevertheless, appears better fitted than any other that has been broached to explain, if it be possible to explain, somewhat of the manner in which organized beings may have arisen and succeeded each other. In this dilemma we might take advantage of Mr. Darwin's candid admission, that he by no means expects to convince old and experienced people, whose minds are stocked with a multitude of facts all regarded during a long course of years from the old point of view. This is nearly our case. So, owning no call to a larger faith than is expected of us, but not prepared to pronounce the whole hypothesis untenable, under such construction as we should put upon it, we naturally sought to attain a settled conviction through a perusal of several proffered refutations of the theory. At least, this course seemed to offer the readiest way of bringing to a head the various objections to which the theory is exposed. On several accounts some of these opposed reviews especially invite examination. We propose, accordingly, to conclude our task with an article upon "Darwin and his Reviewers." III The origin of species, like all origination, like the institution of any other natural state or order, is beyond our immediate ken. We see or may learn how things go on; we can only frame hypotheses as to how they began. Two hypotheses divide the scientific world, very unequally, upon the origin of the existing diversity of the plants and animals which surround us. One assumes that the actual kinds are primordial; the other, that they are derivative. One, that all kinds originated supernaturally and directly as such, and have continued unchanged in the order of Nature; the other, that the present kinds appeared in some sort of genealogical connection with other and earlier kinds, that they became what they now are in the course of time and in the order of Nature. Or, bringing in the word species, which is well defined as "the perennial succession of individuals," commonly of very like individuals--as a close corporation of individuals perpetuated by generation, instead of election--and reducing the question to mathematical simplicity of statement: species are lines of individuals coming down from the past and running on to the future; lines receding, therefore, from our view in either direction. Within our limited observation they appear to be parallel lines, as a general thing neither approaching to nor diverging from each other. The first hypothesis assumes that they were parallel from the unknown beginning and will be to the unknown end. The second hypothesis assumes that the apparent parallelism is not real and complete, at least aboriginally, but approximate or temporary; that we should find the lines convergent in the past, if we could trace them far enough; that some of them, if produced back, would fall into certain fragments of lines, which have left traces in the past, lying not exactly in the same direction, and these farther back into others to which they are equally unparallel. It will also claim that the present lines, whether on the whole really or only approximately parallel, sometimes fork or send off branches on one side or the other, producing new lines (varieties), which run for a while, and for aught we know indefinitely when not interfered with, near and approximately parallel to the parent line. This claim it can establish; and it may also show that these close subsidiary lines may branch or vary again, and that those branches or varieties which are best adapted to the existing conditions may be continued, while others stop or die out. And so we may have the basis of a real theory of the diversification of species and here indeed, there is a real, though a narrow, established ground to build upon But as systems of organic Nature, both doctrines are equally hypotheses, are suppositions of what there is no proof of from experience, assumed in order to account for the observed phenomena, and supported by such indirect evidence as can be had. Even when the upholders of the former and more popular system mix up revelation with scientific discussion--which we decline to do--they by no means thereby render their view other than hypothetical. Agreeing that plants and animals were produced by Omnipotent fiat does not exclude the idea of natural order and what we call secondary causes. The record of the fiat--"Let the earth bring forth grass, the herb yielding seed," etc., "and it was so;" "let the earth bring forth the living creature after his kind, cattle and creeping thing and beast of the earth after his kind, and it was so"--seems even to imply them. Agreeing that they were formed of "the dust of the ground," and of thin air, only leads to the conclusion that the pristine individuals were corporeally constituted like existing individuals, produced through natural agencies. To agree that they were created "after their kinds" determines nothing as to what were the original kinds, nor in what mode, during what time, and in what connections it pleased the Almighty to introduce the first individuals of each sort upon the earth. Scientifically considered, the two opposing doctrines are equally hypothetical. The two views very unequally divide the scientific world; so that believers in "the divine right of majorities" need not hesitate which side to take, at least for the present. Up to a time quite within the memory of a generation still on the stage, two hypotheses about the nature of light very unequally divided the scientific world. But the small minority has already prevailed: the emission theory has gone out; the undulatory or wave theory, after some fluctuation, has reached high tide, and is now the pervading, the fully-established system. There was an intervening time during which most physicists held their opinions in suspense. The adoption of the undulatory theory of light called for the extension of the same theory to heat, and this promptly suggested the hypothesis of a correlation, material connection, and transmutability of heat, light, electricity, magnetism, etc.; which hypothesis the physicists held in absolute suspense until very lately, but are now generally adopting. If not already established as a system, it promises soon to become so. At least, it is generally received as a tenable and probably true hypothesis. Parallel to this, however less cogent the reasons, Darwin and others, having shown it likely that some varieties of plants or animals have diverged in time into cognate species, or into forms as different as species, are led to infer that all species of a genus may have thus diverged from a common stock, and thence to suppose a higher community of origin in ages still farther back, and so on. Following the safe example of the physicists, and acknowledging the fact of the diversification of a once homogeneous species into varieties, we may receive the theory of the evolution of these into species, even while for the present we hold the hypothesis of a further evolution in cool suspense or in grave suspicion. In respect to very many questions a wise man's mind rests long in a state neither of belief nor unbelief. But your intellectually short-sighted people are apt to be preternaturally clear-sighted, and to find their way very plain to positive conclusions upon one side or the other of every mooted question. In fact, most people, and some philosophers, refuse to hold questions in abeyance, however incompetent they may be to decide them. And, curiously enough, the more difficult, recondite, and perplexing, the questions or hypotheses are--such, for instance, as those about organic Nature--the more impatient they are of suspense. Sometimes, and evidently in the present case, this impatience grows out of a fear that a new hypothesis may endanger cherished and most important beliefs. Impatience under such circumstances is not unnatural, though perhaps needless, and, if so, unwise. To us the present revival of the derivative hypothesis, in a more winning shape than it ever before had, was not unexpected. We wonder that any thoughtful observer of the course of investigation and of speculation in science should not have foreseen it, and have learned at length to take its inevitable coming patiently; the more so, as in Darwin's treatise it comes in a purely scientific form, addressed only to scientific men. The notoriety and wide popular perusal of this treatise appear to have astonished the author even more than the book itself has astonished the reading world Coming as the new presentation does from a naturalist of acknowledged character and ability and marked by a conscientiousness and candor which have not always been reciprocated we have thought it simply right to set forth the doctrine as fairly and as favorably as we could There are plenty to decry it and the whole theory is widely exposed to attack For the arguments on the other side we may look to the numerous adverse publications which Darwin s volume has already called out and especially to those reviews which propose directly to refute it. Taking various lines and reflecting very diverse modes of thought, these hostile critics may be expected to concentrate and enforce the principal objections which can be brought to bear against the derivative hypothesis in general, and Darwin's new exposition of it in particular. Upon the opposing side of the question we have read with attention--1. An article in the North American Review for April last; 2. One in the Christian Examiner, Boston, for May; 3. M. Pictet's article in the Bibliotheque Universelle, which we have already made considerable use of, which seems throughout most able and correct, and which in tone and fairness is admirably in contrast with--4. The article in the Edinburgh Review for May, attributed--although against a large amount of internal presumptive evidence--to the most distinguished British comparative anatomist; 5. An article in the North British Review for May; 6. Prof. Agassiz has afforded an early opportunity to peruse the criticisms he makes in the forthcoming third volume of his great work, by a publication of them in advance in the American Journal of Science for July. In our survey of the lively discussion which has been raised, it matters little how our own particular opinions may incline. But we may confess to an impression, thus far, that the doctrine of the permanent and complete immutability of species has not been established, and may fairly be doubted. We believe that species vary, and that "Natural Selection" works; but we suspect that its operation, like every analogous natural operation, may be limited by something else. Just as every species by its natural rate of reproduction would soon completely fill any country it could live in, but does not, being checked by some other species or some other condition--so it may be surmised that variation and natural selection have their struggle and consequent check, or are limited by something inherent in the constitution of organic beings. We are disposed to rank the derivative hypothesis in its fullness with the nebular hypothesis, and to regard both as allowable, as not unlikely to prove tenable in spite of some strong objections, but as not therefore demonstrably true. Those, if any there be, who regard the derivative hypothesis as satisfactorily proved, must have loose notions as to what proof is. Those who imagine it can be easily refuted and cast aside, must, we think, have imperfect or very prejudiced conceptions of the facts concerned and of the questions at issue. We are not disposed nor prepared to take sides for or against the new hypothesis, and so, perhaps, occupy a good position from which to watch the discussion and criticise those objections which are seemingly inconclusive. On surveying the arguments urged by those who have undertaken to demolish the theory, we have been most impressed with a sense of their great inequality. Some strike us as excellent and perhaps unanswerable; some, as incongruous with other views of the same writers; others, when carried out, as incompatible with general experience or general beliefs, and therefore as proving too much; still others, as proving nothing at all; so that, on the whole, the effect is rather confusing and disappointing. We certainly expected a stronger adverse case than any which the thoroughgoing opposers of Darwin appear to have made out. Wherefore, if it be found that the new hypothesis has grown upon our favor as we proceeded, this must be attributed not so much to the force of the arguments of the book itself as to the want of force of several of those by which it has been assailed. Darwin's arguments we might resist or adjourn; but some of the refutations of it give us more concern than the book itself did. These remarks apply mainly to the philosophical and theological objections which have been elaborately urged, almost exclusively by the American reviewers. The North British reviewer, indeed, roundly denounces the book as atheistical, but evidently deems the case too clear for argument. The Edinburgh reviewer, on the contrary, scouts all such objections--as well he may, since he records his belief in "a continuous creative operation," a constantly operating secondary creational law," through which species are successively produced; and he emits faint, but not indistinct, glimmerings of a transmutation theory of his own;[III-8] so that he is equally exposed to all the philosophical objections advanced by Agassiz, and to most of those urged by the other American critics, against Darwin himself. Proposing now to criticise the critics, so far as to see what their most general and comprehensive objections amount to, we must needs begin with the American reviewers, and with their arguments adduced to prove that a derivative hypothesis ought not to be true, or is not possible, philosophical, or theistic. It must not be forgotten that on former occasions very confident judgments have been pronounced by very competent persons, which have not been finally ratified. Of the two great minds of the seventeenth century, Newton and Leibnitz, both profoundly religious as well as philosophical, one produced the theory of gravitation, the other objected to that theory that it was subversive of natural religion. The nebular hypothesis--a natural consequence of the theory of gravitation and of the subsequent progress of physical and astronomical discovery--has been denounced as atheistical even down to our own day. But it is now largely adopted by the most theistical natural philosophers as a tenable and perhaps sufficient hypothesis, and where not accepted is no longer objected to, so far as we know, on philosophical or religious grounds. The gist of the philosophical objections urged by the two Boston reviewers against an hypothesis of the derivation of species--or at least against Darwin's particular hypothesis-- is, that it is incompatible with the idea of any manifestation of design in the universe, that it denies final causes. A serious objection this, and one that demands very serious attention. The proposition, that things and events in Nature were not designed to be so, if logically carried out, is doubtless tantamount to atheism. Yet most people believe that some were designed and others were not, although they fall into a hopeless maze whenever they undertake to define their position. So we should not like to stigmatize as atheistically disposed a person who regards certain things and events as being what they are through designed laws (whatever that expression means), but as not themselves specially ordained, or who, in another connection, believes in general, but not in particular Providence. We could sadly puzzle him with questions; but in return he might equally puzzle us. Then, to deny that anything was specially designed to be what it is, is one proposition; while to deny that the Designer supernaturally or immediately made it so, is another: though the reviewers appear not to recognize the distinction. Also, "scornfully to repudiate" or to "sneer at the idea of any manifestation of design in the material universe,"[III-9] is one thing; while to consider, and perhaps to exaggerate, the difficulties which attend the practical application of the doctrine of final causes to certain instances, is quite another thing: yet the Boston reviewers, we regret to say, have not been duly regardful of the difference. Whatever be thought of Darwin's doctrine, we are surprised that he should be charged with scorning or sneering at the opinions of others, upon such a subject. Perhaps Darwin' s view is incompatible with final causes--we will consider that question presently-- but as to the Examiner's charge, that he "sneers at the idea of any manifestation of design in the material universe," though we are confident that no misrepresentation was intended, we are equally confident that it is not at all warranted by the two passages cited in support of it. Here are the passages: "If green woodpeckers alone had existed, or we did not know that there were many black and pied kinds, I dare say that we should have thought that the green color was a beautiful adaptation to hide this tree-frequenting bird from its enemies." "If our reason leads us to admire with enthusiasm a multitude of inimitable contrivances in Nature, this same reason tells us, though we may easily err on both sides, that some contrivances are less perfect. Can we consider the sting of the wasp or of the bee as perfect, which, when used against many attacking animals, cannot be withdrawn, owing to the backward serratures, and so inevitably causes the death of the insect by tearing out its viscera?" If the sneer here escapes ordinary vision in the detached extracts (one of them wanting the end of the sentence), it is, if possible, more imperceptible when read with the context. Moreover, this perusal inclines us to think that the Examiner has misapprehended the particular argument or object, as well as the spirit, of the author in these passages. The whole reads more naturally as a caution against the inconsiderate use of final causes in science, and an illustration of some of the manifold errors and absurdities which their hasty assumption is apt to involve--considerations probably equivalent to those which induced Lord Bacon to liken final causes to "vestal virgins." So, if any one, it is here Bacon that "sitteth in the seat of the scornful." As to Darwin, in the section from which the extracts were made, he is considering a subsidiary question, and trying to obviate a particular difficulty, but, we suppose, is wholly unconscious of denying "any manifestation of design in the material universe." He concludes the first sentence: --"and consequently that it was a character of importance, and might have been acquired through natural selection; as it is, I have no doubt that the color is due to some quite distinct cause, probably to sexual selection." After an illustration from the vegetable creation, Darwin adds: "The naked skin on the head of a vulture is generally looked at as a direct adaptation for wallowing in putridity; and so it may be, or it may possibly be due to the direct action of putrid matter; but we should be very cautious in drawing any such inference, when we see that the skin on the head of the clean-feeding male turkey is likewise naked. The sutures in the skulls of young mammals have been advanced as a beautiful adaptation for aiding parturition, and no doubt they facilitate or may be indispensable for this act; but as sutures occur in the skulls of young birds and reptiles, which have only to escape from a broken egg, we may infer that this structure has arisen from the laws of growth, and has been taken advantage of in the parturition of the higher animals." All this, simply taken, is beyond cavil, unless the attempt to explain scientifically how any designed result is accomplished savors of impropriety. In the other place, Darwin is contemplating the patent fact that "perfection here below" is relative, not absolute--and illustrating this by the circumstance that European animals, and especially plants, are now proving to be better adapted for New Zealand than many of the indigenous ones--that "the correction for the aberration of light is said, on high authority, not to be quite perfect even in that most perfect organ, the eye." And then follows the second extract of the reviewer. But what is the position of the reviewer upon his own interpretation of these passages? If he insists that green woodpeckers were specifically created so in order that they might be less liable to capture, must he not equally hold that the black and pied ones were specifically made of these colors in order that they might be more liable to be caught? And would an explanation of the mode in which those woodpeckers came to be green, however complete, convince him that the color was undesigned? As to the other illustration, is the reviewer so complete an optimist as to insist that the arrangement and the weapon are wholly perfect (quoad the insect) the normal use of which often causes the animal fatally to injure or to disembowel itself? Either way it seems to us that the argument here, as well as the insect, performs hari-kari. The Examiner adds: "We should in like manner object to the word favorable, as implying that some species are placed by the Creator under unfavorable circumstances, at least under such as might be advantageously modified." But are not many individuals and some races of men placed by the Creator "under unfavorable circumstances, at least under such as might be advantageously modified?" Surely these reviewers must be living in an ideal world, surrounded by "the faultless monsters which our world ne'er saw," in some elysium where imperfection and distress were never heard of! Such arguments resemble some which we often hear against the Bible, holding that book responsible as if it originated certain facts on the shady side of human nature or the apparently darker lines of Providential dealing, though the facts are facts of common observation and have to be confronted upon any theory. The North American reviewer also has a world of his own--just such a one as an idealizing philosopher would be apt to devise--that is, full of sharp and absolute distinctions: such, for instance, as the "absolute invariableness of instinct;" an absolute want of intelligence in any brute animal; and a complete monopoly of instinct by the brute animals, so that this "instinct is a great matter" for them only, since it sharply and perfectly distinguishes this portion of organic Nature from the vegetable kingdom on the one hand and from man on the other: most convenient views for argumentative purposes, but we suppose not borne out in fact. In their scientific objections the two reviewers take somewhat different lines; but their philosophical and theological arguments strikingly coincide. They agree in emphatically asserting that Darwin's hypothesis of the origination of species through variation and natural selection "repudiates the whole doctrine of final causes," and "all indication of design or purpose in the organic world . . . is neither more nor less than a formal denial of any agency beyond that of a blind chance in the developing or perfecting of the organs or instincts of created beings. . . . It is in vain that the apologists of this hypothesis might say that it merely attributes a different mode and time to the Divine agency--that all the qualities subsequently appearing in their descendants must have been implanted, and have remained latent in the original pair." Such a view, the Examiner declares, "is nowhere stated in this book, and would be, we are sure, disclaimed by the author." We should like to be informed of the grounds of this sureness. The marked rejection of spontaneous generation--the statement of a belief that all animals have descended from four or five progenitors, and plants from an equal or lesser number, or, perhaps, if constrained to it by analogy, "from some one primordial form into which life was first breathed"--coupled with the expression, "To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes," than "that each species has been independently created"--these and similar expressions lead us to suppose that the author probably does accept the kind of view which the Examiner is sure he would disclaim. At least, we charitably see nothing in his scientific theory to hinder his adoption of Lord Bacon's "Confession of Faith" in this regard-- "That, notwithstanding God hath rested and ceased from creating, yet, nevertheless, he doth accomplish and fulfill his divine will in all things, great and small, singular and general, as fully and exactly by providence as he could by miracle and new creation, though his working be not immediate and direct, but by compass; not violating Nature, which is his own law upon the creature." However that may be, it is undeniable that Mr. Darwin has purposely been silent upon the philosophical and theological applications of his theory. This reticence, under the circumstances, argues design, and raises inquiry as to the final cause or reason why. Here, as in higher instances, confident as we are that there is a final cause, we must not be overconfident that we can infer the particular or true one. Perhaps the author is more familiar with natural-historical than with philosophical inquiries, and, not having decided which particular theory about efficient cause is best founded, he meanwhile argues the scientific questions concerned--all that relates to secondary causes--upon purely scientific grounds, as he must do in any case. Perhaps, confident, as he evidently is, that his view will finally be adopted, he may enjoy a sort of satisfaction in hearing it denounced as sheer atheism by the inconsiderate, and afterward, when it takes its place with the nebular hypothesis and the like, see this judgment reversed, as we suppose it would be in such event. Whatever Mr. Darwin's philosophy may be, or whether he has any, is a matter of no consequence at all, compared with the important questions, whether a theory to account for the origination and diversification of animal and vegetable forms through the operation of secondary causes does or does not exclude design; and whether the establishment by adequate evidence of Darwin's particular theory of diversification through variation and natural selection would essentially alter the present scientific and philosophical grounds for theistic views of Nature. The unqualified affirmative judgment rendered by the two Boston reviewers, evidently able and practised reasoners, "must give us pause." We hesitate to advance our conclusions in opposition to theirs. But, after full and serious consideration, we are constrained to say that, in our opinion, the adoption of a derivative hypothesis, and of Darwin's particular hypothesis, if we understand it, would leave the doctrines of final causes, utility, and special design, just where they were before. We do not pretend that the subject is not environed with difficulties. Every view is so environed; and every shifting of the view is likely, if it removes some difficulties, to bring others into prominence. But we cannot perceive that Darwin's theory brings in any new kind of scientific difficulty, that is, any with which philosophical naturalists were not already familiar. Since natural science deals only with secondary or natural causes, the scientific terms of a theory of derivation of species--no less than of a theory of dynamics--must needs be the same to the theist as to the atheist. The difference appears only when the inquiry is carried up to the question of primary cause--a question which belongs to philosophy. Wherefore, Darwin 's reticence about efficient cause does not disturb us. He considers only the scientific questions. As already stated, we think that a theistic view of Nature is implied in his book, and we must charitably refrain from suggesting the contrary until the contrary is logically deduced from his premises. If, however, he anywhere maintains that the natural causes through which species are diversified operate without an ordaining and directing intelligence, and that the orderly arrangements and admirable adaptations we see all around us are fortuitous or blind, undesigned results--that the eye, though it came to see, was not designed for seeing, nor the hand for handling--then, we suppose, he is justly chargeable with denying, and very needlessly denying, all design in organic Nature; otherwise, we suppose not. Why, if Darwin's well-known passage about the eye[III-10] equivocal though some of the language be--does not imply ordaining and directing intelligence, then he refutes his own theory as effectually as any of his opponents are likely to do. He asks: "May we not believe that [under variation proceeding long enough, generation multiplying the better variations times enough, and natural selection securing the improvements] a living optical instrument might be thus formed as superior to one of glass as the works of the Creator are to those of man?" This must mean one of two things: either that the living instrument was made and perfected under (which is the same thing as by) an intelligent First Cause, or that it was not. If it was, then theism is asserted; and as to the mode of operation, how do we know, and why must we believe, that, fitting precedent forms being in existence, a living instrument (so different from a lifeless manufacture) would be originated and perfected in any other way, or that this is not the fitting way? If it means that it was not, if he so misuses words that by the Creator he intends an unintelligent power, undirected force, or necessity, then he has put his case so as to invite disbelief in it. For then blind forces have produced not only manifest adaptions of means to specific ends--which is absurd enough--but better adjusted and more perfect instruments or machines than intellect (that is, human intellect) can contrive and human skill execute--which no sane person will believe. On the other hand, if Darwin even admits--we will not say adopts--the theistic view, he may save himself much needless trouble in the endeavor to account for the absence of every sort of intermediate form. Those in the line between one species and another supposed to be derived from it he may be bound to provide; but as to "an infinite number of other varieties not intermediate, gross, rude, and purposeless, the unmeaning creations of an unconscious cause," born only to perish, which a relentless reviewer has imposed upon his theory--rightly enough upon the atheistic alternative--the theistic view rids him at once of this "scum of creation." For, as species do not now vary at all times and places and in all directions, nor produce crude, vague, imperfect, and useless forms, there is no reason for supposing that they ever did. Good-for-nothing monstrosities, failures of purpose rather than purposeless, indeed, sometimes occur; but these are just as anomalous and unlikely upon Darwin's theory as upon any other. For his particular theory is based, and even over-strictly insists, upon the most universal of physiological laws, namely, that successive generations shall differ only slightly, if at all, from their parents; and this effectively excludes crude and impotent forms. Wherefore, if we believe that the species were designed, and that natural propagation was designed, how can we say that the actual varieties of the species were not equally designed? Have we not similar grounds for inferring design in the supposed varieties of species, that we have in the case of the supposed species of a genus? When a naturalist comes to regard as three closely related species what he before took to be so many varieties of one species how has he thereby strengthened our conviction that the three forms are designed to have the differences which they actually exhibit? Wherefore so long as gradatory, orderly, and adapted forms in Nature argue design, and at least while the physical cause of variation is utterly unknown and mysterious, we should advise Mr. Darwin to assume in the philosophy of his hypothesis that variation has been led along certain beneficial lines. Streams flowing over a sloping plain by gravitation (here the counterpart of natural selection) may have worn their actual channels as they flowed; yet their particular courses may have been assigned; and where we see them forming definite and useful lines of irrigation, after a manner unaccountable on the laws of gravitation and dynamics, we should believe that the distribution was designed. To insist, therefore, that the new hypothesis of the derivative origin of the actual species is incompatible with final causes and design, is to take a position which we must consider philosophically untenable. We must also regard it as highly unwise and dangerous, in the present state and present prospects of physical and physiological science. We should expect the philosophical atheist or skeptic to take this ground; also, until better informed, the unlearned and unphilosophical believer; but we should think that the thoughtful theistic philosopher would take the other side. Not to do so seems to concede that only supernatural events can be shown to be designed, which no theist can admit--seems also to misconceive the scope and meaning of all ordinary arguments for design in Nature. This misconception is shared both by the reviewers and the reviewed. At least, Mr. Darwin uses expressions which imply that the natural forms which surround us, because they have a history or natural sequence, could have been only generally, but not particularly designed--a view at once superficial and contradictory; whereas his true line should be, that his hypothesis concerns the order and not the cause, the how and not the why of the phenomena, and so leaves the question of design just where it was before. To illustrate this from the theist's point of view: Transfer the question for a moment from the origination of species to the origination of individuals, which occurs, as we say, naturally. Because natural, that is, "stated, fixed, or settled," is it any the less designed on that account? We acknowledge that God is our maker--not merely the originator of the race, but our maker as individuals--and none the less so because it pleased him to make us in the way of ordinary generation. If any of us were born unlike our parents and grandparents, in a slight degree, or in whatever degree, would the case be altered in this regard? The whole argument in natural theology proceeds upon the ground that the inference for a final cause of the structure of the hand and of the valves in the veins is just as valid now, in individuals produced through natural generation, as it would have been in the case of the first man, supernaturally created. Why not, then, just as good even on the supposition of the descent of men from chimpanzees and gorillas, since those animals possess these same contrivances? Or, to take a more supposable case: If the argument from structure to design is convincing when drawn from a particular animal, say a Newfoundland dog, and is not weakened by the knowledge that this dog came from similar parents, would it be at all weakened if, in tracing his genealogy, it were ascertained that he was a remote descendant of the mastiff or some other breed, or that both these and other breeds came (as is suspected) from some wolf? If not, how is the argument for design in the structure of our particular dog affected by the supposition that his wolfish progenitor came from a post-tertiary wolf, perhaps less unlike an existing one than the dog in question is to some other of the numerous existing races of dogs, and that this post-tertiary came from an equally or more different tertiary wolf? And if the argument from structure to design is not invalidated by our present knowledge that our individual dog was developed from a single organic cell, how is it invalidated by the supposition of an analogous natural descent, through a long line of connected forms, from such a cell, or from some simple animal, existing ages before there were any dogs? Again, suppose we have two well-known and apparently most decidedly different animals or plants, A and D, both presenting, in their structure and in their adaptations to the conditions of existence, as valid and clear evidence of design as any animal or plant ever presented: suppose we have now discovered two intermediate species, B and C, which make up a series with equable differences from A to D. Is the proof of design or final cause in A and D, whatever it amounted to, at all weakened by the discovery of the intermediate forms? Rather does not the proof extend to the intermediate species, and go to show that all four were equally designed? Suppose, now, the number of intermediate forms to be much increased, and therefore the gradations to be closer yet--as close as those between the various sorts of dogs, or races of men, or of horned cattle: would the evidence of design, as shown in the structure of any of the members of the series, be any weaker than it was in the case of A and D? Whoever contends that it would be, should likewise maintain that the origination of individuals by generation is incompatible with design, or an impossibility in Nature. We might all have confidently thought the latter, antecedently to experience of the fact of reproduction. Let our experience teach us wisdom. These illustrations make it clear that the evidence of design from structure and adaptation is furnished complete by the individual animal or plant itself, and that our knowledge or our ignorance of the history of its formation or mode of production adds nothing to it and takes nothing away. We infer design from certain arrangements and results; and we have no other way of ascertaining it. Testimony, unless infallible, cannot prove it, and is out of the question here. Testimony is not the appropriate proof of design: adaptation to purpose is. Some arrangements in Nature appear to be contrivances, but may leave us in doubt. Many others, of which the eye and the hand are notable examples, compel belief with a force not appreciably short of demonstration. Clearly to settle that such as these must have been designed goes far toward proving that other organs and other seemingly less explicit adaptations in Nature must also have been designed, and clinches our belief, from manifold considerations, that all Nature is a preconcerted arrangement, a manifested design. A strange contradiction would it be to insist that the shape and markings of certain rude pieces of flint, lately found in drift-deposits, prove design, but that nicer and thousand-fold more complex adaptations to use in animals and vegetables do not a fortiori argue design. We could not affirm that the arguments for design in Nature are conclusive to all minds. But we may insist, upon grounds already intimated, that, whatever they were good for before Darwin's book appeared, they are good for now. To our minds the argument from design always appeared conclusive of the being and continued operation of an intelligent First Cause, the Ordainer of Nature; and we do not see that the grounds of such belief would be disturbed or shifted by the adoption of Darwin's hypothesis. We are not blind to the philosophical difficulties which the thoroughgoing implication of design in Nature has to encounter, nor is it our vocation to obviate them It suffices us to know that they are not new nor peculiar difficulties--that, as Darwin's theory and our reasonings upon it did not raise these perturbing spirits, they are not bound to lay them. Meanwhile, that the doctrine of design encounters the very same difficulties in the material that it does in the moral world is Just what ought to be expected. So the issue between the skeptic and the theist is only the old one, long ago argued out--namely, whether organic Nature is a result of design or of chance. Variation and natural selection open no third alternative; they concern only the question how the results, whether fortuitous or designed, may have been brought about. Organic Nature abounds with unmistakable and irresistible indications of design, and, being a connected and consistent system, this evidence carries the implication of design throughout the whole. On the other hand, chance carries no probabilities with it, can never be developed into a consistent system, but, when applied to the explanation of orderly or beneficial results, heaps up improbabilities at every step beyond all computation. To us, a fortuitous Cosmos is simply inconceivable. The alternative is a designed Cosmos. It is very easy to assume that, because events in Nature are in one sense accidental, and the operative forces which bring them to pass are themselves blind and unintelligent (physically considered, all forces are), therefore they are undirected, or that he who describes these events as the results of such forces thereby assumes that they are undirected. This is the assumption of the Boston reviewers, and of Mr. Agassiz, who insists that the only alternative to the doctrine, that all organized beings were supernaturally created just as they are, is, that they have arisen spontaneously through the omnipotence of matter.[III-11] As to all this, nothing is easier than to bring out in the conclusion what you introduce in the premises. If you import atheism into your conception of variation and natural selection, you can readily exhibit it in the result. If you do not put it in, perhaps there need be none to come out. While the mechanician is considering a steamboat or locomotive-engine as a material organism, and contemplating the fuel, water, and steam, the source of the mechanical forces, and how they operate, he may not have occasion to mention the engineer. But, the orderly and special results accomplished, the why the movements are in this or that particular direction, etc., is inexplicable without him. If Mr. Darwin believes that the events which he supposes to have occurred and the results we behold were undirected and undesigned, or if the physicist believes that the natural forces to which he refers phenomena are uncaused and undirected, no argument is needed to show that such belief is atheism. But the admission of the phenomena and of these natural processes and forces does not necessitate any such belief, nor even render it one whit less improbable than before. Surely, too, the accidental element may play its part in Nature without negativing design in the theist's view. He believes that the earth's surface has been very gradually prepared for man and the existing animal races, that vegetable matter has through a long series of generations imparted fertility to the soil in order that it may support its present occupants, that even beds of coal have been stored up for man's benefit Yet what is more accidental, and more simply the consequence of physical agencies than the accumulation of vegetable matter in a peat bog and its transformation into coal? No scientific person at this day doubts that our solar system is a progressive development, whether in his conception he begins with molten masses, or aeriform or nebulous masses, or with a fluid revolving mass of vast extent, from which the specific existing worlds have been developed one by one What theist doubts that the actual results of the development in the inorganic worlds are not merely compatible with design but are in the truest sense designed re suits? Not Mr. Agassiz, certainly, who adopts a remarkable illustration of design directly founded on the nebular hypothesis drawing from the position and times of the revolution of the world, so originated direct evidence that the physical world has been ordained in conformity with laws which obtain also among living beings But the reader of the interesting exposition[III-12] will notice that the designed result has been brought to pass through what, speaking after the manner of men, might be called a chapter of accidents. A natural corollary of this demonstration would seem to be, that a material connection between a series of created things--such as the development of one of them from another, or of all from a common stock--is highly compatible with their intellectual connection, namely, with their being designed and directed by one mind. Yet upon some ground which is not explained, and which we are unable to conjecture, Mr. Agassiz concludes to the contrary in the organic kingdoms, and insists that, because the members of such a series have an intellectual connection, "they cannot be the result of a material differentiation of the objects themselves,"[III-13] that is, they cannot have had a genealogical connection. But is there not as much intellectual connection between the successive generations of any species as there is between the several species of a genus, or the several genera of an order? As the intellectual connection here is realized through the material connection, why may it not be so in the case of species and genera? On all sides, therefore, the implication seems to be quite the other way. Returning to the accidental element, it is evident that the strongest point against the compatibility of Darwin's hypothesis with design in Nature is made when natural selection is referred to as picking out those variations which are improvements from a vast number which are not improvements, but perhaps the contrary, and therefore useless or purposeless, and born to perish. But even here the difficulty is not peculiar; for Nature abounds with analogous instances. Some of our race are useless, or worse, as regards the improvement of mankind; yet the race may be designed to improve, and may be actually improving. Or, to avoid the complication with free agency--the whole animate life of a country depends absolutely upon the vegetation, the vegetation upon the rain. The moisture is furnished by the ocean, is raised by the sun's heat from the ocean's surface, and is wafted inland by the winds. But what multitudes of raindrops fall back into the ocean--are as much without a final cause as the incipient varieties which come to nothing! Does it therefore follow that the rains which are bestowed upon the soil with such rule and average regularity were not designed to support vegetable and animal life? Consider, likewise, the vast proportion of seeds and pollen, of ova and young--a thousand or more to one--which come to nothing, and are therefore purposeless in the same sense, and only in the same sense, as are Darwin's unimproved and unused slight variations. The world is full of such cases; and these must answer the argument--for we cannot, except by thus showing that it proves too much. Finally, it is worth noticing that, though natural selection is scientifically explicable, variation is not. Thus far the cause of variation, or the reason why the offspring is sometimes unlike the parents, is just as mysterious as the reason why it is generally like the parents. It is now as inexplicable as any other origination; and, if ever explained, the explanation will only carry up the sequence of secondary causes one step farther, and bring us in face of a somewhat different problem, but which will have the same element of mystery that the problem of variation has now. Circumstances may preserve or may destroy the variations man may use or direct them but selection whether artificial or natural no more originates them than man originates the power which turns a wheel when he dams a stream and lets the water fall upon it The origination of this power is a question about efficient cause. The tendency of science in respect to this obviously is not toward the omnipotence of matter, as some suppose, but to ward the omnipotence of spirit. So the real question we come to is as to the way in which we are to conceive intelligent and efficient cause to be exerted, and upon what exerted. Are we bound to suppose efficient cause in all cases exerted upon nothing to evoke something into existence--and this thousands of times repeated, when a slight change in the details would make all the difference between successive species? Why may not the new species, or some of them, be designed diversifications of the old? There are, perhaps, only three views of efficient cause which may claim to be both philosophical and theistic: 1. The view of its exertion at the beginning of time, endowing matter and created things with forces which do the work and produce the phenomena. 2. This same view, with the theory of insulated interpositions, or occasional direct action, engrafted upon it--the view that events and operations in general go on in virtue simply of forces communicated at the first, but that now and then, and only now and then, the Deity puts his hand directly to the work. 3. The theory of the immediate, orderly, and constant, however infinitely diversified, action of the intelligent efficient Cause. It must be allowed that, while the third is preeminently the Christian view, all three are philosophically compatible with design in Nature. The second is probably the popular conception. Perhaps most thoughtful people oscillate from the middle view toward the first or the third--adopting the first on some occasions, the third on others. Those philosophers who like and expect to settle all mooted questions will take one or the other extreme. The Examiner inclines toward, the North American reviewer fully adopts, the third view, to the logical extent of maintaining that "the origin of an individual, as well as the origin of a species or a genus, can be explained only by the direct action of an intelligent creative cause." To silence his critics, this is the line for Mr. Darwin to take; for it at once and completely relieves his scientific theory from every theological objection which his reviewers have urged against it. At present we suspect that our author prefers the first conception, though he might contend that his hypothesis is compatible with either of the three. That it is also compatible with an atheistic or pantheistic conception of the universe, is an objection which, being shared by all physical, and some ethical or moral science, cannot specially be urged against Darwin's system. As he rejects spontaneous generation, and admits of intervention at the beginning of organic life, and probably in more than one instance, he is not wholly excluded from adopting the middle view, although the interventions he would allow are few and far back. Yet one interposition admits the principle as well as more. Interposition presupposes particular necessity or reason for it, and raises the question, when and how often it may have been necessary. It might be the natural supposition, if we had only one set of species to account for, or if the successive inhabitants of the earth had no other connections or resemblances than those which adaptation to similar conditions, which final causes in the narrower sense, might explain. But if this explanation of organic Nature requires one to "believe that, at innumerable periods in the earth's history, certain elemental atoms have been commanded suddenly to flash into living tissues," and this when the results are seen to be strictly connected and systematic, we cannot wonder that such interventions should at length be considered, not as interpositions or interferences, but rather--to use the reviewer's own language--as "exertions so frequent and beneficent that we come to regard them as the ordinary action of Him who laid the foundation of the earth, and without whom not a sparrow falleth to the ground."[III-14] What does the difference between Mr. Darwin and his reviewer now amount to? If we say that according to one view the origination of species is natural, according to the other miraculous, Mr. Darwin agrees that "what is natural as much requires and presupposes an intelligent mind to render it so-- that is, to effect it continually or at stated times--as what is supernatural does to effect it for once."[III-15] He merely inquires into the form of the miracle, may remind us that all recorded miracles (except the primal creation of matter) were transformations or actions in and upon natural things, and will ask how many times and how frequently may the origination of successive species be repeated before the supernatural merges in the natural. In short, Darwin maintains that the origination of a species, no less than that of an individual, is natural; the reviewer, that the natural origination of an individual, no less than the origination of a species, requires and presupposes Divine power. A fortiori, then, the origination of a variety requires and presupposes Divine power. And so between the scientific hypothesis of the one and the philosophical conception of the other no contrariety remains. And so, concludes the North American reviewer, "a proper view of the nature of causation places the vital doctrine of the being and the providence of a God on ground that can never be shaken."[III-16] A worthy conclusion, and a sufficient answer to the denunciations and arguments of the rest of the article, so far as philosophy and natural theology are concerned. If a writer must needs use his own favorite dogma as a weapon with which to give coup de grace to a pernicious theory, he should be careful to seize his edge-tool by the handle, and not by the blade. We can barely glance at a subsidiary philosophical objection of the North American reviewer, which the Examiner also raises, though less explicitly. Like all geologists, Mr. Darwin draws upon time in the most unlimited manner. He is not peculiar in this regard. Mr. Agassiz tells us that the conviction is "now universal, among well-informed naturalists, that this globe has been in existence for innumerable ages, and that the length of time elapsed since it first became inhabited cannot be counted in years;" Pictet, that the imagination refuses to calculate the immense number of years and of ages during which the faunas of thirty or more epochs have succeeded one another, and developed their long succession of generations. Now, the reviewer declares that such indefinite succession of ages is "virtually infinite," "lacks no characteristic of eternity except its name," at least, that "the difference between such a conception and that of the strictly infinite, if any, is not appreciable." But infinity belongs to metaphysics. Therefore, he concludes, Darwin supports his theory, not by scientific but by metaphysical evidence; his theory is "essentially and completely metaphysical in character, resting altogether upon that idea of �the infinite' which the human mind can neither put aside nor comprehend."[III-17] And so a theory which will be generally regarded as much too physical is transferred by a single syllogism to metaphysics. Well, physical geology must go with it: for, even on the soberest view, it demands an indefinitely long time antecedent to the introduction of organic life upon our earth. A fortiori is physical astronomy a branch of metaphysics, demanding, as it does, still larger "instalments of infinity," as the reviewer calls them, both as to time and number. Moreover, far the greater part of physical inquiries now relate to molecular actions, which, a distinguished natural philosopher informs us, "we have to regard as the results of an infinite number of in finitely small material particles, acting on each other at infinitely small distances"--a triad of infinities--and so physics becomes the most metaphysical of sciences. Verily, if this style of reasoning is to prevail-- "Thinking is but an idle waste of thought, And naught is everything, and everything is naught." The leading objection of Mr. Agassiz is likewise of a philosophical character. It is, that species exist only "as categories of thought"--that, having no material existence, they can have had no material variation, and no material community of origin. Here the predication is of species in the subjective sense, the inference in the objective sense. Reduced to plain terms, the argument seems to be: Species are ideas; therefore the objects from which the idea is derived cannot vary or blend, and cannot have had a genealogical connection. The common view of species is, that, although they are generalizations, yet they have a direct objective ground in Nature, which genera, orders, etc., have not. According to the succinct definition of Jussieu--and that of Linnaeus is identical in meaning--a species is the perennial succession of similar individuals in continued generations. The species is the chain of which the individuals are the links. The sum of the genealogically-connected similar individuals constitutes the species, which thus has an actuality and ground of distinction not shared by genera and other groups which were not supposed to be genealogically connected. How a derivative hypothesis would modify this view, in assigning to species only a temporary fixity, is obvious. Yet, if naturalists adopt that hypothesis, they will still retain Jussieu's definition, which leaves untouched the question as to how and when the "perennial successions" were established. The practical question will only be, How much difference between two sets of individuals entitles them to rank under distinct species? and that is the practical question now, on whatever theory. The theoretical question is--as stated at the beginning of this article--whether these specific lines were always as distinct as now. Mr. Agassiz has "lost no opportunity of urging the idea that, while species have no material existence, they yet exist as categories of thought in the same way [and only in the same way] as genera, families, orders, classes," etc. He "has taken the ground that all the natural divisions in the animal kingdom are primarily distinct, founded upon different categories of characters, and that all exist in the same way, that is, as categories of thought, embodied in individual living forms. I have attempted to show that branches in the animal kingdom are founded upon different plans of structure, and for that very reason have embraced from the beginning representatives between which there could be no community of origin; that classes are founded upon different modes of execution of these plans, and therefore they also embrace representatives which could have no community of origin; that orders represent the different degrees of complication in the mode of execution of each class, and therefore embrace representatives which could not have a community of origin any more than the members of different classes or branches; that families are founded upon different patterns of form, and embrace, representatives equally independent in their origin; that genera are founded upon ultimate peculiarities of structure, embracing representatives which, from the very nature of their peculiarities, could have no community of origin; and that, finally, species are based upon relations--and proportions that exclude, as much as all the preceding distinctions, the idea of a common descent. "As the community of characters among the beings belonging to these different categories arises from the intellectual connection which shows them to be categories of thought, they cannot be the result of a gradual material differentiation of the objects themselves. The argument on which these views are founded may be summed up in the following few words: Species, genera, families, etc., exist as thoughts, individuals as facts."[III-18] An ingenious dilemma caps the argument: "It seems to me that there is much confusion of ideas in the general statement of the variability of species so often repeated lately. If species do not exist at all, as the supporters of the transmutation theory maintain, how can they vary? And if individuals alone exist, how can the differences which may be observed among them prove the variability of species?" Now, we imagine that Mr. Darwin need not be dangerously gored by either horn of this curious dilemma. Although we ourselves cherish old-fashioned prejudices in favor of the probable permanence, and therefore of a more stable objective ground of species, yet we agree--and Mr. Darwin will agree fully with Mr. Agassiz--that species, and he will add varieties, "exist as categories of thought," that is, as cognizable distinctions--which is all that we can make of the phrase here, whatever it may mean in the Aristotelian metaphysics. Admitting that species are only categories of thought, and not facts or things, how does this prevent the individuals, which are material things, from having varied in the course of time, so as to exemplify the present almost innumerable categories of thought, or embodiments of Divine thought in material forms, or--viewed on the human side--in forms marked with such orderly and graduated resemblances and differences as to suggest to our minds the idea of species, genera, orders, etc., and to our reason the inference of a Divine Original? We have no clear idea how Mr. Agassiz intends to answer this question, in saying that branches are founded upon different plans of structure, classes upon different mode of execution of these plans, orders on different degrees of complication in the mode of execution, families upon different patterns of form, genera upon ultimate peculiarities of structure, and species upon relations and proportions. That is, we do not perceive how these several "categories of thought" exclude the possibility or the probability that the individuals which manifest or suggest the thoughts had an ultimate community of origin. Moreover, Mr. Darwin might insinuate that the particular philosophy of classification upon which this whole argument reposes is as purely hypothetical and as little accepted as is his own doctrine. If both are pure hypotheses, it is hardly fair or satisfactory to extinguish the one by the other. If there is no real contradiction between them, nothing is gained by the attempt. As to the dilemma propounded, suppose we try it upon that category of thought which we call chair. This is a genus, comprising a common chair (Sella vulgaris), arm or easy chair (S. cathedra), the rocking-chair (S. oscillans)--widely distributed in the United States--and some others, each of which has sported, as the gardeners say, into many varieties. But now, as the genus and the species have no material existence, how can they vary? If only individual chairs exist, how can the differences which may be observed among them prove the variability of the species? To which we reply by asking, Which does the question refer to, the category of thought, or the individual embodiment? If the former, then we would remark that our categories of thought vary from time to time in the readiest manner. And, although the Divine thoughts are eternal, yet they are manifested to us in time and succession, and by their manifestation only can we know them, how imperfectly! Allowing that what has no material existence can have had no material connection or variation, we should yet infer that what has intellectual existence and connection might have intellectual variation; and, turning to the individuals, which represent the species, we do not see how all this shows that they may not vary. Observation shows us that they do. Wherefore, taught by fact that successive individuals do vary, we safely infer that the idea must have varied, and that this variation of the individual representatives proves the variability of the species, whether objectively or subjectively regarded. Each species or sort of chair, as we have said, has its varieties, and one species shades off by gradations into another. And--note it well--these numerous and successively slight variations and gradations, far from suggesting an accidental origin to chairs and to their forms, are very proofs of design. Again, edifice is a generic category of thought. Egyptian, Grecian, Byzantine, and Gothic buildings are well-marked species, of which each individual building of the sort is a material embodiment. Now, the question is, whether these categories or ideas may not have been evolved, one from another in succession, or from some primal, less specialized, edificial category. What better evidence for such hypothesis could we have than the variations and grades which connect these species with each other? We might extend the parallel, and get some good illustrations of natural selection from the history of architecture, and the origin of the different styles under different climates and conditions. Two considerations may qualify or limit the comparison. One, that houses do not propagate, so as to produce continuing lines of each sort and variety; but this is of small moment on Agassiz's view, he holding that genealogical connection is not of the essence of a species at all. The other, that the formation and development of the ideas upon which human works proceed are gradual; or, as the same great naturalist well states it, "while human thought is consecutive, Divine thought is simultaneous." But we have no right to affirm this of Divine action. We must close here. We meant to review some of the more general scientific objections which we thought not altogether tenable. But, after all, we are not so anxious just now to know whether the new theory is well founded on facts, as whether it would be harmless if it were. Besides, we feel quite unable to answer some of these objections, and it is pleasanter to take up those which one thinks he can. Among the unanswerable, perhaps the weightiest of the objections, is that of the absence, in geological deposits, of vestiges of the intermediate forms which the theory requires to have existed. Here all that Mr. Darwin can do is to insist upon the extreme imperfection of the geological record and the uncertainty of negative evidence. But, withal, he allows the force of the objection almost as much as his opponents urge it--so much so, indeed, that two of his English critics turn the concession unfairly upon him, and charge him with actually basing his hypothesis upon these and similar difficulties--as if he held it because of the difficulties, and not in spite of them; a handsome return for his candor! As to this imperfection of the geological record, perhaps we should get a fair and intelligible illustration of it by imagining the existing animals and plants of New England, with all their remains and products since the arrival of the Mayflower, to be annihilated; and that, in the coming time, the geologists of a new colony, dropped by the New Zealand fleet on its way to explore the ruins of London, undertake, after fifty years of examination, to reconstruct in a catalogue the flora and fauna of our day, that is, from the close of the glacial period to the present time. With all the advantages of a surface exploration, what a beggarly account it would be! How many of the land animals and plants which are enumerated in the Massachusetts official reports would it be likely to contain? Another unanswerable question asked by the Boston reviewers is, Why, when structure and instinct or habit vary-- as they must have varied, on Darwin's hypothesis--they vary together and harmoniously, instead of vaguely? We cannot tell, because we cannot tell why either varies at all. Yet, as they both do vary in successive generations--as is seen under domestication--and are correlated, we can only adduce the fact. Darwin may be precluded from our answer, but we may say that they vary together because designed to do so. A reviewer says that the chance of their varying together is inconceivably small; yet, if they do not, the variant individuals must all perish. Then it is well that it is not left to chance. To refer to a parallel case: before we were born, nourishment and the equivalent to respiration took place in a certain way. But the moment we were ushered into this breathing world, our actions promptly conformed, both as to respiration and nourishment, to the before unused structure and to the new surroundings. "Now," says the Examiner, "suppose, for instance, the gills of an aquatic animal converted into lungs, while instinct still compelled a continuance under water, would not drowning ensue?" No doubt. But--simply contemplating the facts, instead of theorizing--we notice that young frogs do not keep their heads under water after ceasing to be tadpoles. The instinct promptly changes with the structure, without supernatural interposition--just as Darwin would have it, if the development of a variety or incipient species, though rare, were as natural as a metamorphosis. "Or if a quadruped, not yet furnished with wings, were suddenly inspired with the instinct of a bird, and precipitated itself from a cliff, would not the descent be hazardously rapid?" Doubtless the animal would be no better supported than the objection. But Darwin makes very little indeed of voluntary efforts as a cause of change, and even poor Lamarck need not be caricatured. He never supposed that an elephant would take such a notion into his wise head, or that a squirrel would begin with other than short and easy leaps; yet might not the length of the leap be increased by practice? The North American reviewer's position, that the higher brute animals have comparatively little instinct and no intelligence, is a heavy blow and great discouragement to dogs, horses, elephants, and monkeys. Thus stripped of their all, and left to shift for themselves as they may in this hard world, their pursuit and seeming attainment of knowledge under such peculiar difficulties are interesting to contemplate. However, we are not so sure as is the critic that instinct regularly increases downward and decreases upward in the scale of being. Now that the case of the bee is reduced to moderate proportions,[III-19] we know of nothing in instinct surpassing that of an animal so high as a bird, the talegal, the male of which plumes himself upon making a hot-bed in which to batch his partner's eggs--which he tends and regulates the beat of about as carefully and skillfully as the unplumed biped does an eccaleobion.[III-20] As to the real intelligence of the higher brutes, it has been ably defended by a far more competent observer, Mr. Agassiz, to whose conclusions we yield a general assent, although we cannot quite place the best of dogs "in that respect upon a level with a considerable proportion of poor humanity," nor indulge the hope, or indeed the desire, of a renewed acquaintance with the whole animal kingdom in a future life. The assertion that acquired habitudes or instincts, and acquired structures, are not heritable, any breeder or good observer can refute. That "the human mind has become what it is out of a developed instinct," is a statement which Mr. Darwin nowhere makes, and, we presume, would not accept. That he would have us believe that individual animals acquire their instincts gradually,[III-21] is a statement which must have been penned in inadvertence both of the very definition of instinct, and of everything we know of in Mr. Darwin's book. It has been attempted to destroy the very foundation of Darwin's hypothesis by denying that there are any wild varieties, to speak of, for natural selection to operate upon. We cannot gravely sit down to prove that wild varieties abound. We should think it just as necessary to prove that snow falls in winter. That variation among plants cannot be largely due to hybridism, and that their variation in Nature is not essentially different from much that occurs in domestication, and, in the long-run, probably hardly less in amount, we could show if our space permitted. As to the sterility of hybrids, that can no longer be insisted upon as absolutely true, nor be practically used as a test between species and varieties, unless we allow that hares and rabbits are of one species. That such sterility, whether total or partial, subserves a purpose in keeping species apart, and was so designed, we do not doubt. But the critics fail to perceive that this sterility proves nothing whatever against the derivative origin of the actual species; for it may as well have been intended to keep separate those forms which have reached a certain amount of divergence, as those which were always thus distinct. The argument for the permanence of species, drawn from the identity with those now living of cats, birds, and other animals preserved in Egyptian catacombs, was good enough as used by Cuvier against St.-Hilaire, that is, against the supposition that time brings about a gradual alteration of whole species; but it goes for little against Darwin, unless it be proved that species never vary, or that the perpetuation of a variety necessitates the extinction of the parent breed. For Darwin clearly maintains--what the facts warrant--that the mass of a species remains fixed so long as it exists at all, though it may set off a variety now and then. The variety may finally supersede the parent form, or it may coexist with it; yet it does not in the least hinder the unvaried stock from continuing true to the breed, unless it crosses with it. The common law of inheritance may be expected to keep both the original and the variety mainly true as long as they last, and none the less so because they have given rise to occasional varieties. The tailless Manx cats, like the curtailed fox in the fable, have not induced the normal breeds to dispense with their tails, nor have the Dorkings (apparently known to Pliny) affected the permanence of the common sort of fowl. As to the objection that the lower forms of life ought, on Darwin's theory, to have been long ago improved out of existence, and replaced by higher forms, the objectors forget what a vacuum that would leave below, and what a vast field there is to which a simple organization is best adapted, and where an advance would be no improvement, but the contrary. To accumulate the greatest amount of being upon a given space, and to provide as much enjoyment of life as can be under the conditions, is what Nature seems to aim at; and this is effected by diversification. Finally, we advise nobody to accept Darwin's or any other derivative theory as true. The time has not come for that, and perhaps never will. We also advise against a similar credulity on the other side, in a blind faith that species--that the manifold sorts and forms of existing animals and vegetables--"have no secondary cause." The contrary is already not unlikely, and we suppose will hereafter become more and more probable. But we are confident that, if a derivative hypothesis ever is established, it will be so on a solid theistic ground. Meanwhile an inevitable and legitimate hypothesis is on trial--an hypothesis thus far not untenable--a trial just now very useful to science, and, we conclude, not harmful to religion, unless injudicious assailants temporarily make it so. One good effect is already manifest; its enabling the advocates of the hypothesis of a multiplicity of human species to perceive the double insecurity of their ground. When the races of men are admitted to be of one species, the corollary, that they are of one origin, may be expected to follow. Those who allow them to be of one species must admit an actual diversification into strongly-marked and persistent varieties, and so admit the basis of fact upon which the Darwinian hypothesis is built; while those, on the other hand, who recognize several or numerous human species, will hardly be able to maintain that such species were primordial and supernatural in the ordinary sense of the word. The English mind is prone to positivism and kindred forms of materialistic philosophy, and we must expect the derivative theory to be taken up in that interest. We have no predilection for that school, but the contrary. If we had, we might have looked complacently upon a line of criticism which would indirectly, but effectively, play into the hands of positivists and materialistic atheists generally. The wiser and stronger ground to take is, that the derivative hypothesis leaves the argument for design, and therefore for a designer, as valid as it ever was; that to do any work by an instrument must require, and therefore presuppose, the exertion rather of more than of less power than to do it directly; that whoever would be a consistent theist should believe that Design in the natural world is coextensive with Providence, and hold as firmly to the one as he does to the other, in spite of the wholly similar and apparently insuperable difficulties which the mind encounters whenever it endeavors to develop the idea into a system, either in the material and organic, or in the moral world. It is enough, in the way of obviating objections, to show that the philosophical difficulties of the one are the same, and only the same, as of the other. IV SPECIES AS TO VARIATION, GEOGRAPHICAL DISTRIBUTION, AND SUCCESSION (American Journal of Science and Arts, May, 1863) Etude sur l'Espece, a l'Occasion d'une Revision de la Famille des Cupuliferes, par M. ALPHONSE DE CANDOLLE.-- This is the title of a paper by M. Alph. De Candolle, growing out of his study of the oaks. It was published in the November number of the Bibliotheque Universelle, and separately issued as a pamphlet. A less inspiring task could hardly be assigned to a botanist than the systematic elaboration of the genus Quercus and its allies. The vast materials assembled under De Candolle's hands, while disheartening for their bulk, offered small hope of novelty. The subject was both extremely trite and extremely difficult. Happily it occurred to De Candolle that an interest might be imparted to an onerous undertaking, and a work of necessity be turned to good account for science, by studying the oaks in view of the question of species. What this term species means, or should mean, in natural history, what the limits of species, inter se or chronologically, or in geographical distribution, their modifications, actual or probable, their origin, and their destiny--these are questions which surge up from time to time; and now and then in the progress of science they come to assume a new and hopeful interest. Botany and zoology, geology, and what our author, feeling the want of a new term proposes to name epiontology, [IV-1] all lead up to and converge into this class of questions, while recent theories shape and point the discussion So we look with eager interest to see what light the study of oaks by a very careful experienced and conservative botanist, particularly conversant with the geographical relations of plants may throw upon the subject. The course of investigation in this instance does not differ from that ordinarily pursued by working botanists nor, in deed are the theoretical conclusions other than those to which a similar study of other orders might not have equally led. The oaks afford a very good occasion for the discussion of questions which press upon our attention, and perhaps they offer peculiarly good materials on account of the number of fossil species. Preconceived notions about species being laid aside, the specimens in hand were distributed, according to their obvious resemblances, into groups of apparently identical or nearly identical forms, which were severally examined and compared. Where specimens were few, as from countries little explored, the work was easy, but the conclusions, as will be seen, of small value. The fewer the materials, the smaller the likelihood of forms intermediate between any two, and--what does not appear being treated upon the old law-maxim as non-existent--species are readily enough defined. Where, however, specimens abound, as in the case of the oaks of Europe, of the Orient, and of the United States, of which the specimens amounted to hundreds, collected at different ages, in varied localities, by botanists of all sorts of views and predilections--here alone were data fit to draw useful conclusions from. Here, as De Candolle remarks, he had every advantage, being furnished with materials more complete than any one person could have procured from his own herborizations, more varied than if he had observed a hundred times over the same forms in the same district, and more impartial than if they had all been amassed by one person with his own ideas or predispositions. So that vast herbaria, into which contributions from every source have flowed for years, furnish the best possible data--at least are far better than any practicable amount of personal herborization--or the comparative study of related forms occurring over wide tracts of territory. But as the materials increase, so do the difficulties. Forms, which appeared totally distinct, approach or blend through intermediate gradations; characters, stable in a limited number of instances or in a limited district, prove unstable occasionally, or when observed over a wider area; and the practical question is forced upon the investigator, What here is probably fixed and specific, and what is variant, pertaining to individual, variety, or race? In the examination of these rich materials, certain characters were found to vary upon the same branch, or upon the same tree, sometimes according to age or development, sometimes irrespective of such relations or of any assignable reasons. Such characters, of course, are not specific, although many of them are such as would have been expected to be constant in the same species, and are such as generally enter into specific definitions. Variations of this sort, De Candolle, with his usual painstaking, classifies and tabulates, and even expresses numerically their frequency in certain species. The results are brought well to view in a systematic enumeration: 1. Of characters which frequently vary upon the same branch: over a dozen such are mentioned. 2. Of those which sometimes vary upon the same branch: a smaller number of these are mentioned. 3. Those so rare that they might be called monstrosities. Then he enumerates characters, ten in number, which he has never found to vary on the same branch, and which, therefore, may better claim to be employed as specific. But, as among them he includes the duration of the leaves, the size of the cupule, and the form and size of its scales, which are by no means quite uniform in different trees of the same species, even these characters must be taken with allowance. In fact, having first brought together, as groups of the lowest order, those forms which varied upon the same stock, he next had to combine similarly various forms which, though not found associated upon the same branch, were thoroughly blended by intermediate degrees: "The lower groups (varieties or races) being thus constituted, I have given the rank of species to the groups next above these, which differ in other respects, i.e., either in characters which were not found united upon certain individuals, or in those which do not show transitions from one individual to another. For the oaks of regions sufficiently known, the species thus formed rest upon satisfactory bases, of which the proof can be furnished. It is quite otherwise with those which are represented in our herbaria by single or few specimens. These are provisional species--species which may hereafter fall to the rank of simple varieties. I have not been inclined to prejudge such questions; indeed, in this regard, I am not disposed to follow those authors whose tendency is, as they say, to reunite species. I never reunite them without proof in each particular case; while the botanists to whom I refer do so on the ground of analogous variations or transitions occurring in the same genus or in the same family. For example resting on the fact that Quercus hex, Q. coccifera, Q. acutifolia, etc., have the leaves sometimes entire and sometimes toothed upon the same branch, or present transitions from one tree to another, I might readily have united my Q. Tlapuxahuensis to Q. Sartorii of Liebmann, since these two differ only in their entire or their toothed leaves. From the fact that the length of the peduncle varies in Q. Robur and many other oaks, I might have combined Q. Seemannii Liebm. with Q. salicifolia Nee. I have not admitted these inductions, but have demanded visible proof in each particular case. Many species are thus left as provisional; but, in proceeding thus, the progress of the science will be more regular, and the synonymy less dependent upon the caprice or the theoretical opinions of each author." This is safe and to a certain degree judicious, no doubt, as respects published species. Once admitted, they may stand until they are put down by evidence, direct or circumstantial. Doubtless a species may rightfully be condemned on good circumstantial evidence. But what course does De Candolle pursue in the case--of every-day occurrence to most working botanists, having to elaborate collections from countries not so well explored as Europe--when the forms in question, or one of the two, are as yet unnamed? Does he introduce as a new species every form which he cannot connect by ocular proof with a near relative, from which it differs only in particulars which he sees are inconstant in better known species of the same group? We suppose not. But, if he does, little improvement for the future upon the state of things revealed in the following quotation can be expected: "In the actual state of our knowledge, after having seen nearly all the original specimens, and in some species as many as two hundred representatives from different localities, I estimate that, out of the three hundred species of Cupuliferae which will be enumerated in the Prodromus, two-thirds at least are provisional species. In general, when we consider what a multitude of species were described from a single specimen, or from the forms of a single locality, of a single country, or are badly described, it is difficult to believe that above one-third of the actual species in botanical works will remain unchanged." Such being the results of the want of adequate knowledge, how is it likely to be when our knowledge is largely increased? The judgment of so practised a botanist as De Candolle is important in this regard, and it accords with that of other botanists of equal experience. "They are mistaken," he pointedly asserts, "who repeat that the greater part of our species are clearly limited, and that the doubtful species are in a feeble minority. This seemed to be true, so long as a genus was imperfectly known, and its species were founded upon few specimens, that is to say, were provisional. Just as we come to know them better, intermediate forms flow in, and doubts as to specific limits augment." De Candolle insists, indeed, in this connection, that the higher the rank of the groups the more definite their limitation, or, in other terms, the fewer the ambiguous or doubtful forms, that genera are more strictly limited than species tribes than genera, orders than tribes, etc. We are not convinced of this Often where it has appeared to be so, advancing discovery has brought intermediate forms to light, perplexing to the systematist. "They are mistaken, we think more than one systematic botanist will say, "who repeat that the greater part of our natural orders and tribes are absolutely limited," however we may agree that we will limit them. Provisional genera we suppose are proportionally hardly less common than provisional species; and hundreds of genera are kept up on considerations of general propriety or general convenience, although well known to shade off into adjacent ones by complete gradations. Somewhat of this greater fixity of higher groups, therefore, is rather apparent than real. On the other hand, that varieties should be less definite than species, follows from the very terms employed. They are ranked as varieties, rather than species, just because of their less definiteness. Singular as it may appear, we have heard it denied that spontaneous varieties occur. De Candolle makes the important announcement that, in the oak genus, the best known species are just those which present the greatest number of spontaneous varieties and sub-varieties. The maximum is found in Q. Robur, with twenty-eight varieties, all spontaneous. Of Q. Lusitanica eleven varieties are enumerated, of Q. Calliprinos ten, of Q. coccifera eight, * etc. And he significantly adds that "these very species which offer such numerous modifications are themselves ordinarily surrounded by other forms, provisionally called species, because of the absence of known transitions or variations, but to which some of these will probably have to be joined hereafter." The inference is natural, if not inevitable, that the difference between such species and such varieties is only one of degree, either as to amount of divergence, or of hereditary fixity, or as to the frequency or rarity at the present time of intermediate forms. This brings us to the second section of De Candolle's article, in which he passes on, from the observation of the present forms and affinities of cupuliferous plants, to the consideration of their probable history and origin. Suffice it to say, that he frankly accepts the inferences derived from the whole course of observation, and contemplates a probable historical connection between congeneric species. He accepts and, by various considerations drawn from the geographical distribution of European Cupuliferae, fortifies the conclusion--long ago arrived at by Edward Forbes--that the present species, and even some of their varieties, date back to about the close of the Tertiary epoch, since which time they have been subject to frequent and great changes of habitation or limitation, but without appreciable change of specific form or character; that is, without profounder changes than those within which a species at the present time is known to vary. Moreover, he is careful to state that he is far from concluding that the time of the appearance of a species in Europe at all indicates the time of its origin. Looking back still further into the Tertiary epoch, of which the vegetable remains indicate many analogous, but few, if any, identical forms, he concludes, with Heer and others, that specific changes of form, as well as changes of station, are to be presumed; and, finally, that "the theory of a succession of forms through the deviation of anterior forms is the most natural hypothesis, and the most accordant with the known facts in palaeontology, geographical botany and zoology, of anatomical structure and classification: but direct proof of it is wanting, and moreover, if true, it must have taken place very slowly; so slowly, indeed, that its effects are discernible only after a lapse of time far longer than our historic epoch." In contemplating the present state of the species of Cupuliferae in Europe, De Candolle comes to the conclusion that, while the beech is increasing, and extending its limits southward and westward (at the expense of Coniferae and birches), the common oak, to some extent, and the Turkey oak decidedly, are diminishing and retreating, and this wholly irrespective of man's agency. This is inferred of the Turkey oak from the great gaps found in its present geographical area, which are otherwise inexplicable, and which he regards as plain indications of a partial extinction. Community of descent of all the individuals of species is of course implied in these and all similar reasonings. An obvious result of such partial extinction is clearly enough brought to view The European oaks (like the American species) greatly tend to vary that is they manifest an active disposition to produce new forms Every form tends to become hereditary and so to pass from the state of mere variation to that of race and of these competing incipient races some only will survive. Quercus Robur offers a familiar illustration of the manner in which one form may in the course of time become separated into two or more distinct ones. To Linnaeus this common oak of Europe was all of one species. But of late years the greater number of European botanists have regarded it as including three species, Q. pedunculata, Q. sessiliflora, and Q. pubescens. De Candolle looks with satisfaction to the independent conclusion which he reached from a long and patient study of the forms (and which Webb, Gay, Bentham, and others, had equally reached), that the view of Linnaeus was correct, inasmuch as it goes to show that the idea and the practical application of the term species have remained unchanged during the century which has elapsed since the publication of the "Species Plantarum." But, the idea remaining unchanged, the facts might appear under a different aspect, and the conclusion be different, under a slight and very supposable change of circumstances. Of the twenty-eight spontaneous varieties of Q. Robur, which De Candolle recognizes, all but six, he remarks, fall naturally under the three sub-species, pedunculata, sessiliflora, and pubescens, and are therefore forms grouped around these as centres; and, moreover, the few connecting forms are by no means the most common. Were these to die out, it is clear that the three forms which have already been so frequently taken for species would be what the group of four or five provisionally admitted species which closely surround Q. Robur now are. The best example of such a case, as having in all probability occurred through geographical segregation and partial extinction, is that of the cedar, thus separated into the Deodar, the Lebanon, and the Atlantic cedars--a case admirably worked out by Dr. Hooker two or three years ago. [IV-2] A special advantage of the Cupuliferae for determining the probable antiquity of existing species in Europe, De Candolle finds in the size and character of their fruits. However it may be with other plants (and he comes to the conclusion generally that marine currents and all other means of distant transport have played only a very small part in the actual dispersion of species), the transport of acorns and chestnuts by natural causes across an arm of the sea in a condition to germinate, and much more the spontaneous establishment of a forest of oaks or chestnuts in this way, De Candolle conceives to be fairly impossible in itself, and contrary to all experience. From such considerations, i.e., from the actual dispersion of the existing species (with occasional aid from post-tertiary deposits), it is thought to be shown that the principal Cupuliferae of the Old World attained their actual extension before the present separation of Sicily, Sardinia and Corsica, and of Britain, from the European Continent. This view once adopted, and this course once entered upon, has to be pursued farther. Quercus Robur of Europe with its bevy of admitted derivatives, and its attending species only provisionally admitted to that rank, is very closely related to certain species of Eastern Asia, and of Oregon and California--so closely that "a view of the specimens by no means forbids the idea that they have all originated from Q. Robur, or have originated, with the latter, from one or more preceding forms so like the present ones that a naturalist could hardly know whether to call them species or varieties." Moreover, there are fossil leaves from diluvian deposits in Italy, figured by Gaudin, which are hardly distinguishable from those of Q. Robur on the one hand, and from those of Q. Douglasii, etc., of California, on the other. No such leaves are found in any tertiary deposit in Europe; but such are found of that age, it appears, in Northwest America, where their remote descendants still flourish. So that the probable genealogy of Q. Robur, traceable in Europe up to the commencement of the present epoch, looks eastward and far into the past on far-distant shores. Quercus Ilex, the evergreen oak of Southern Europe and Northern Africa, reveals a similar archaeology; but its presence in Algeria leads De Candolle to regard it as a much more ancient denizen of Europe than Q. Robur; and a Tertiary oak, Q. ilicoides, from a very old Miocene bed in Switzerland, is thought to be one of its ancestral forms. This high antiquity once established, it follows almost of course that the very nearly-related species in Central Asia, in Japan, in California, and even our own live-oak with its Mexican relatives, may probably enough be regarded as early offshoots from the same stock with Q. hex. In brief--not to continue these abstracts and remarks, and without reference to Darwin's particular theory (which De Candolle at the close very fairly considers)--if existing species, or many of them, are as ancient as they are now generally thought to be, and were subject to the physical and geographical changes (among them the coming and the going of the glacial epoch) which this antiquity implies; if in former times they were as liable to variation as they now are; and if the individuals of the same species may claim a common local origin, then we cannot wonder that "the theory of a succession of forms by deviations of anterior forms" should be regarded as "the most natural hypothesis," nor at the general advance made toward its acceptance. The question being, not, how plants and animals originated, but, how came the existing animals and plants to be just where they are and what they are, it is plain that naturalists interested in such inquiries are mostly looking for the answer in one direction. The general drift of opinion, or at least of expectation, is exemplified by this essay of De Candolle; and the set and force of the current are seen by noticing how it carries along naturalists of widely different views and prepossessions--some faster and farther than others--but all in one way. The tendency is, we may say, to extend the law of continuity, or something analogous to it, from inorganic to organic Nature, and in the latter to connect the present with the past in some sort of material connection. The generalization may indeed be expressed so as not to assert that the connection is genetic, as in Mr. Wallace's formula: "Every species has come into existence coincident both in time and space with preexisting closely-allied species." Edward Forbes, who may be called the originator of this whole line of inquiry, long ago expressed a similar view. But the only material sequence we know, or can clearly conceive, in plants and animals, is that from parent to progeny; and, as De Candolle implies, the origin of species and that of races can hardly be much unlike, nor governed by other than the same laws, whatever these may be. The progress of opinion upon this subject in one generation is not badly represented by that of De Candolle himself, who is by no means prone to adopt new views without much consideration. In an elementary treatise published in the year 1835, he adopted and, if we rightly remember, vigorously maintained, Schouw's idea of the double or multiple origin of species, at least of some species--a view which has been carried out to its ultimate development only perhaps by Agassiz, in the denial of any necessary genetic connection among the individuals of the same species, or of any original localization more restricted than the area now occupied by the species. But in i855, in his "Geographic Botanique," the multiple hypothesis, although in principle not abandoned, loses its point, in view of the probable high antiquity of existing species. The actual vegetation of the world being now regarded as a continuation, through numerous geological, geographical, and more recently historical changes, of anterior vegetations, the actual distribution of plants is seen to be a consequence of preceding conditions; and geological considerations, and these alone, may be expected to explain all the facts--many of them so curious and extraordinary--of the actual geographical distribution of the species. In the present essay, not only the distribution but the origin of congeneric species is regarded as something derivative; whether derived by slow and very gradual changes in the course of ages, according to Darwin, or by a sudden, inexplicable change of their tertiary ancestors, as conceived by Heer, De Candolle hazards no opinion. It may, however, be inferred that he looks upon "natural selection" as a real, but insufficient cause; while some curious remarks upon the number of monstrosities annually produced, and the possibility of their enduring, may be regarded as favorable to Heer's view. As an index to the progress of opinion in the direction referred to, it will be interesting to compare Sir Charles Lyell's well-known chapters of twenty or thirty years ago, in which the permanence of species was ably maintained, with his treatment of the same subject in a work just issued in England, which, however, has not yet reached us. A belief of the derivation of species may be maintained along with a conviction of great persistence of specific characters. This is the idea of the excellent Swiss vegetable palaeontologist, Heer, who imagines a sudden change of specific type at certain periods, and perhaps is that of Pictet. Falconer adheres to somewhat similar views in his elaborate paper on elephants, living and fossil, in the Natural History Review for January last. Noting that "there is clear evidence of the true mammoth having existed in America long after the period of the northern drift, when the surface of the country had settled down into its present form, and also in Europe so late as to have been a contemporary of the Irish elk, and on the other hand that it existed in England so far back as before the deposition of the bowlder clay; also that four well-defined species of fossil elephant are known to have existed in Europe; that "a vast number of the remains of three of these species have been exhumed over a large area in Europe; and, even in the geological sense, an enormous interval of time has elapsed between the formation of the most ancient and the most recent of these deposits, quite sufficient to test the persistence of specific characters in an elephant," he presents the question, "Do, then, the successive elephants occurring in these strata show any signs of a passage from the older form into the newer?" To which the reply is: "If there is one fact which is impressed on the conviction of the observer with more force than any other, it is the persistence and uniformity of the characters of the molar teeth in the earliest known mammoth and his most modern successor . . . Assuming the observation to be correct, what strong proof does it not afford of the persistence and constancy, throughout vast intervals of time, of the distinctive characters of those organs which arc most concerned in the existence and habits of the species? If we cast a glance back on the long vista of physical changes which our planet has undergone since the Neozoic epoch, we can nowhere detect signs of a revolution more sudden and pronounced, or more important in its results, than the intercalation and sudden disappearance of the glacial period. Yet the 'dicyclotherian' mammoth lived before it, and passed through the ordeal of all the hard extremities it involved, bearing his organs of locomotion and digestion all but unchanged. Taking the group of four European fossil species above enumerated, do they show any signs in the successive deposits of a transition from the one form into the other? Here again the result of my observation, in so far as it has extended over the European area, is, that the specific characters of the molars are constant in each, within a moderate range of variation, and that we nowhere meet with intermediate forms." . . . Dr. Falconer continues (page 80): "The inferences which I draw from these facts are not opposed to one of the leading propositions of Darwin's theory. With him, I have no faith in the opinion that the mammoth and other extinct elephants made their appearance suddenly, after the type in which their fossil remains are presented to us. The most rational view seems to be, that they are in some shape the modified descendants of earlier progenitors. But if the asserted facts be correct, they seem clearly to indicate that the older elephants of Europe, such as E. meridionalis and E. antiguus, were not the stocks from which the later species, E. primigenius and E. Africanus sprung, and that we must look elsewhere for their origin. The nearest affinity, and that a very close one, of the European E. meridionalis is with the Miocene E. planifrons of India; and of E. primigenius, with the existing India species. "Another reflection is equally strong in my mind--that the means which have been adduced to explain the origin of the species by 'natural selection,' or a process of variation from external influences, are inadequate to account for the phenomena. The law of phyllotaxis, which governs the evolution of leaves around the axis of a plant, is as nearly constant in its manifestation as any of the physical laws connected with the material world. Each instance, however different from another, can be shown to be a term of some series of continued fractions. When this is coupled with the geometrical law governing the evolution of form, so manifest in some departments of the animal kingdom, e. g., the spiral shells of the Mollusca, it is difficult to believe that there is not, in Nature, a deeper-seated and innate principle, to the operation of which natural selection is merely an adjunct. The whole range of the Mammalia, fossil and recent, cannot furnish a species which has had a wider geographical distribution, and passed through a longer term of time, and through more extreme changes of climatal conditions, than the mammoth. If species are so unstable, and so susceptible of mutation through such influences, why does that extinct form stand out so signally a monument of stability? By his admirable researches and earnest writings, Darwin has, beyond all his contemporaries, given an impulse to the philosophical investigation of the most backward and obscure branch of the biological sciences of his day; he has laid the foundations of a great edifice; but he need not be surprised if, in the progress of erection, the superstructure is altered by his successors, like the Duomo of Milan from the Roman to a different style of architecture." Entertaining ourselves the opinion that something more than natural selection is requisite to account for the orderly production and succession of species, we offer two incidental remarks upon the above extract. 1. We find in it--in the phrase "natural selection, or a process of variation from external influences"--an example of the very common confusion of two distinct things, viz., variation and natural selection. The former has never yet been shown to have its cause in "external influences," nor to occur at random. As we have elsewhere insisted, if not inexplicable, it has never been explained; all we can yet say is, that plants and animals are prone to vary, and that some conditions favor variation. Perhaps in this Dr. Falconer may yet find what he seeks: for "it is difficult to believe that there is not in nature a deeper-seated and innate principle, to the operation of which natural selection is merely an adjunct." The latter, which is the ensemble of the external influences, including the competition of the individuals them selves, picks out certain variations as they arise, but in no proper sense can be said to originate them 2. Although we are not quite sure how Dr Falconer in tends to apply the law of phyllotaxis to illustrate his idea, we fancy that a pertinent illustration may be drawn from it in this way. There are two species of phyllotaxis, perfectly distinct, and we suppose, not mathematically reducible the one to the other, viz.: (1.) That of alternate leaves, with its vane ties and (2.) That of verticillate leaves, of which opposite leaves present the simplest case That although generally constant a change from one variety of alternate phyllotaxis to an other should occur on the same axis, or on successive axes, is not surprising, the different sorts being terms of a regular series--although indeed we have not the least idea as to how the change from the one to the other comes to pass But it is interesting and in this connection perhaps instructive, to remark that while some dicotyledonous plants hold to the verticillate, i.e., opposite-leaved phyllotaxis throughout, a larger number--through the operation of some deep seated and innate principle which we cannot fathom--change abruptly into the other species at the second or third node, and change back again in the flower, or else effect a synthesis of the two species in a manner which is puzzling to understand. Here is a change from one fixed law to another, as unaccountable, if not as great, as from one specific form to another. An elaborate paper on the vegetation of the Tertiary period in the southeast of France, by Count Gaston de Saporta, published in the Annales des Sciences Naturelles in 1862, vol. xvi., pp. 309-344--which we have not space to analyze--is worthy of attention from the general inquirer, on account of its analysis of the Tertiary flora into its separate types, Cretaceous, Austral, Tropical, and Boreal, each of which has its separate and different history--and for the announcement that "the hiatus, which, in the idea of most geologists, intervened between the close of the Cretaceous and the beginning of the Tertiary, appears to have had no existence, so far as concerns the vegetation; that in general it was not by means of a total overthrow, followed by a complete new emission of species, that the flora has been renewed at each successive period; and that while the plants of Southern Europe inherited from the Cretaceous period more or less rapidly disappeared, as also the austral forms, and later the tropical types (except the laurel, the myrtle, and the Chamaerops humilis), the boreal types, coming later, survived all the others, and now compose, either in Europe, or in the north of Asia, or in North America, the basis of the actual arborescent vegetation. Especially "a very considerable number of forms nearly identical with tertiary forms now exist in America, where they have found, more easily than in our soil--less vast and less extended southward--refuge from ulterior revolutions," The extinction of species is attributed to two kinds of causes; the one material or physical, whether slow or rapid; the other inherent in the nature of organic beings, incessant, but slow, in a manner latent, but somehow assigning to the species, as to the individuals, a limited period of existence, and, in some equally mysterious but wholly natural way, connected with the development of organic types: "By type meaning a collection of vegetable forms constructed upon the same plan of organization, of which they reproduce the essential lineaments with certain secondary modifications, and which appear to run back to a common point of departure." In this community of types, no less than in the community of certain existing species, Saporta recognizes a prolonged material union between North America and Europe in former times. Most naturalists and geologists reason in the same way--some more cautiously than others--yet perhaps most of them seem not to perceive how far such inferences imply the doctrine of the common origin of related species. For obvious reasons such doctrines are likely to find more favor with botanists than with zoologists. But with both the advance in this direction is seen to have been rapid and great; yet to us not unexpected. We note, also, an evident disposition, notwithstanding some endeavors to the contrary, to allow derivative hypotheses to stand or fall upon their own merits--to have indeed upon philosophical grounds certain presumptions in their favor--and to be, perhaps, quite as capable of being turned to good account as to bad account in natural theology.[IV-3] Among the leading naturalists, indeed, such views--taken in the widest sense--have one and, so far as we are now aware, only one thoroughgoing and thoroughly consistent opponent, viz., Mr. Agassiz. Most naturalists take into their very conception of a species, explicitly or by implication, the notion of a material connection resulting from the descent of the individuals composing it from a common stock, of local origin. Agassiz wholly eliminates community of descent from his idea of species, and even conceives a species to have been as numerous in individuals and as wide-spread over space, or as segregated in discontinuous spaces, from the first as at the later period. The station which it inhabits, therefore, is with other naturalists in no wise essential to the species, and may not have been the region of its origin. In Agassiz's view the habitat is supposed to mark the origin, and to be a part of the character of the species. The habitat is not merely the place where it is, but a part of what it is. Most naturalists recognize varieties of species; and many, like De Candolle, have come to conclude that varieties of the highest grade, or races, so far partake of the characteristics of species, and are so far governed by the same laws, that it is often very difficult to draw a clear and certain distinction between the two. Agassiz will not allow that varieties or races exist in Nature, apart from man's agency. Most naturalists believe that the origin of species is supernatural, their dispersion or particular geographical area, natural, and their extinction, when they disappear, also the result of physical causes. In the view of Agassiz, if rightly understood, all three are equally independent of physical cause and effect, are equally supernatural. In comparing preceding periods with the present and with each other, most naturalists and palaeontologists now appear to recognize a certain number of species as having survived from one epoch to the next, or even through more than one formation, especially from the Tertiary into the post-Tertiary period, and from that to the present age. Agassiz is understood to believe in total extinctions and total new creations at each successive epoch, and even to recognize no existing species as ever contemporary with extinct ones, except in the case of recent exterminations. These peculiar views if sustained will effectually dispose of every form of derivative hypothesis. Returning for a moment to De Candolle's article, we are disposed to notice his criticism of Linnaeus's "definition" of the term species (Philosophia Botanica, No. 157): "Species tot numeramus quot diversae formae in principio sunt creatae"-- which he declares illogical, inapplicable, and the worst that has been propounded. "So, to determine if a form is specific, it is necessary to go back to its origin which is impossible A definition by a character which can never be verified is no definition at all." Now as Linnaeus practically applied the idea of species with a sagacity which has never been surpassed and rarely equaled and indeed may be said to have fixed its received meaning in natural history, it may well be inferred that in the phrase above cited he did not so much undertake to frame a logical definition, as to set forth the idea which, in his opinion, lay at the foundation of species; on which basis A.L. Jussieu did construct a logical definition--"Nunc rectius definitur perennis individuorum similium successio continuata generatione renascentium." The fundamental idea of species, we would still maintain, is that of a chain of which genetically-connected individuals are the links. That, in the practical recognition of species, the essential characteristic has to be inferred, is no great objection--the general fact that like engenders like being an induction from a vast number of instances, and the only assumption being that of the uniformity of Nature. The idea of gravitation, that of the atomic constitution of matter, and the like, equally have to be verified inferentially. If we still hold to the idea of Linnaeus, and of Agassiz, that existing species were created independently and essentially all at once at the beginning of the present era, we could not better the propositions of Linnaeus and of Jussieu. If; on the other hand, the time has come in which we may accept, with De Candolle, their successive origination, at the commencement of the present era or before, and even by derivation from other forms, then the "in principio" of Linnaeus will refer to that time, whenever it was, and his proposition be as sound and wise as ever. In his "Geographie Botanique" (ii., 1068-1077) De Candolle discusses this subject at length, and in the same interest. Remarking that of the two great facts of species, viz., likeness among the individuals, and genealogical connection, zoologists have generally preferred the latter,[IV-4] while botanists have been divided in opinion, he pronounces for the former as the essential thing, in the following argumentative statement: "Quant a moi, j'ai ete conduit, dans ma definition de l'espece, a mettre decidement la ressemblance au-dessus de caracteres de succession. Ce n'est pas seulement a cause des circonstances propres au regne vegetal, dont je m'occupe exclusivement; ce n'est pas non plus afin de sortir ma definition des theories et de la rendre le plus possible utile aux naturalistes descripteurs et nomenclateurs, c'est aussi par un motif philosophique. En toute chose il faut aller au fond des questions, quand on le peut. Or, pourquoi la reproduction est-elle possible, habituelle, feconde indefiniment, entre des etres organises que nous dirons de la meme espece? Parce qu'ils se ressemblent et uniquement a cause de cela. Lorsque deux especes ne peuvent, ou, s'il s'agit d'animaux superieurs, ne peuvent et ne veulent se croiser, c'est qu'elles sont tres differentes. Si l'on obtient des croisements, c'est que les individus sont analogues; si ces croisements donnent des produits feconds, c'est que les individus etaient plus analogues; si ces produits euxmemes sont feconds, c'est que la ressemblance etait plus grande; s'ils sont fecond habituellement et indefiniment, c'est que la ressemblance interieure et exterieure etait tres grande. Ainsi le degre de ressemblance est le fond; la reproduction en est seulement la manifestation et la mesure, et il est logique de placer la cause au-dessus de l'effet." We are not yet convinced. We still hold that genealogical connection, rather than mutual resemblance, is the fundamental thing--first on the ground of fact, and then from the philosophy of the case. Practically, no botanist can say what amount of dissimilarity is compatible with unity of species; in wild plants it is sometimes very great, in cultivated races often enormous. De Candolle himself informs us that the different variations which the same oak-tree exhibits arc significant indications of a disposition to set up separate varieties, which becoming hereditary may constitute a race; he evidently looks upon the extreme forms, say of Quercus Robur, as having thus originated; and on this ground, inferred from transitional forms, and not from their mutual resemblance, he includes them in that species. This will be more apparent should the discovery of transitions, which he leads us to expect, hereafter cause the four provisional species which attend Q. Robur to be merged in that species. It may rightly be replied that this conclusion would be arrived at from the likeness step by step in the series of forms; but the cause of the likeness here is obvious. And this brings in our "motif philosophique." Not to insist that the likeness is after all the variable, not the constant, element--to learn which is the essential thing, resemblance among individuals or their genetic connection--we have only to ask which can be the cause of the other. In hermaphrodite plants (the normal case), and even as the question is ingeniously put by De Candolle in the above extract, the former surely cannot be the cause of the latter, though it may, in case of crossing, offer occasion. But, on the ground of the most fundamental of all things in the constitution of plants and animals--the fact incapable of further analysis, that individuals reproduce their like, that characteristics are inheritable--the likeness is a direct natural consequence of the genetic succession; "and it is logical to place the cause above the effect." We are equally disposed to combat a proposition of De Candolle's about genera, elaborately argued in the "Geographie Botanique," and incidentally reaffirmed in his present article, viz., that genera are more natural than species, and more correctly distinguished by people in general, as is shown by vernacular names. But we have no space left in which to present some evidence to the contrary. V SEQUOIA AND ITS HISTORY THE RELATIONS OF NORTH AMERICAN TO NORTHEAST ASIAN AND TO TERTIARY VEGETATION (A Presidential Address to the American Association for the Advancement of Science, at Dubuque, August, 1872) The session being now happily inaugurated, your presiding officer of the last year has only one duty to perform before he surrenders the chair to his successor. If allowed to borrow a simile from the language of my own profession, I might liken the President of this Association to a biennial plant. He flourishes for the year in which he comes into existence, and performs his appropriate functions as presiding officer. When the second year comes round, he is expected to blossom out in an address and disappear. Each president, as he retires, is naturally expected to contribute something from his own investigations or his own line of study, usually to discuss some particular scientific topic. Now, although I have cultivated the field of North American botany, with some assiduity, for more than forty years, have reviewed our vegetable hosts, and assigned to no small number of them their names and their place in the ranks, yet, so far as our own wide country is concerned, I have been to a great extent a closet botanist. Until this summer I had not seen the Mississippi, nor set foot upon a prairie. To gratify a natural interest, and to gain some title for addressing a body of practical naturalists and explorers, I have made a pilgrimage across the continent. I have sought and viewed in their native haunts many a plant and flower which for me had long bloomed unseen, or only in the hortus siccus. I have been able to see for myself what species and what forms constitute the main features of the vegetation of each successive region, and record--as the vegetation unerringly does--the permanent characteristics of its climate. Passing on from the eastern district, marked by its equably distributed rainfall, and therefore naturally forest-clad, I have seen the trees diminish in number, give place to wide prairies, restrict their growth to the borders of streams, and then disappear from the boundless drier plains; have seen grassy plains change into a brown and sere desert--desert in the common sense, but hardly anywhere botanically so--have seen a fair growth of coniferous trees adorning the more favored slopes of a mountain-range high enough to compel summer showers; have traversed that broad and bare elevated region shut off on both sides by high mountains from the moisture supplied by either ocean, and longitudinally intersected by sierras which seemingly remain as naked as they were born; and have reached at length the westward slopes of that high mountain-barrier which, refreshed by the Pacific, bears the noble forests of the Sierra Nevada and the Coast Ranges, and among them trees which are the wonder of the world. As I stood in their shade, in the groves of Mariposa and Calaveras, and again under the canopy of the commoner redwood, raised on columns of such majestic height and ample girth, it occurred to me that I could not do better than to share with you, upon this occasion, some of the thoughts which possessed my mind. In their development they may, perhaps, lead us up to questions of considerable scientific interest. I shall not detain you with any remarks--which would now be trite--upon the size or longevity of these far-famed Sequoia-trees, or of the sugar-pines, incense-cedar, and firs associated with them, of which even the prodigious bulk of the dominating Sequoia does not sensibly diminish the grandeur. Although no account and no photographic representation of either species of the far-famed Sequoia-trees gives any adequate impression of their singular majesty--still less of their beauty--yet my interest in them did not culminate merely or mainly in considerations of their size and age. Other trees, in other parts of the world, may claim to be older. Certain Australian gumtrees (Eucalypti) are said to be taller. Some, we are told, rise so high that they might even cast a flicker of shadow upon the summit of the Pyramid of Cheops. Yet the oldest of them doubtless grew from seed which was shed long after the names of the pyramid-builders had been forgotten. So far as we can judge from the actual counting of the layers of several trees, no Sequoia now alive sensibly antedates the Christian era. Nor was I much impressed with an attraction of man's adding. That the more remarkable of these trees should bear distinguishing appellations seems proper enough; but the tablets of personal names which are affixed to many of them 172 in the most visited groves--as if the memory of more or less notable people of our day might be made enduring by the juxtaposition--do suggest some incongruity. When we consider that a hand's breadth at the circumference of any one of the venerable trunks so placarded has recorded in annual lines the lifetime of the individual thus associated with it, one may question whether the next hand's breadth may not measure the fame of some of the names thus ticketed for adventitious immortality. Whether it be the man or the tree that is honored in the connection, probably either would live as long, in fact and in memory, without it. One notable thing about the Sequoia-trees is their isolation. Most of the trees associated with them are of peculiar species, and some of them are nearly as local. Yet every pine, fir, and cypress of California is in some sort familiar, because it has near relatives in other parts of the world. But the redwoods have none. The redwood--including in that name the two species of "big-trees"--belongs to the general Cypress family, but is sui generis. Thus isolated systematically, and extremely isolated geographically, and so wonderful in size and port, they more than other trees suggest questions. Were they created thus local and lonely, denizens of California only; one in limited numbers in a few choice spots on the Sierra Nevada, the other along the Coast Range from the Bay of Monterey to the frontiers of Oregon? Are they veritable Melchizedeks, without pedigree or early relationship, and possibly fated to be without descent? Or are they now coming upon the stage--or rather were they coming but for man's interference--to play a part in the future? Or are they remnants, sole and scanty survivors of a race that has played a grander part in the past, but is now verging to extinction? Have they had a career, and can that career be ascertained or surmised, so that we may at least guess whence they came, and how, and when? SEQUOIA AND ITS HISTORY 173 Time was, and not long ago, when such questions as these were regarded as useless and vain--when students of natural history, unmindful of what the name denotes, were content with a knowledge of things as they now are, but gave little heed as to how they came to be so. Now such questions are held to be legitimate, and perhaps not wholly unanswerable. It cannot now be said that these trees inhabit their present restricted areas simply because they are there placed in the climate and soil of all the world most congenial to them. These must indeed be congenial, or they would not survive. But when we see how the Australian Eucalyptus-trees thrive upon the Californian coast, and how these very redwoods flourish upon another continent; how the so-called wild-oat (Avena sterilis of the Old World) has taken full possession of California; how that cattle and horses, introduced by the Spaniard, have spread as widely and made themselves as much at home on the plains of La Plata as on those of Tartary; and that the cardoon-thistle-seeds, and others they brought with them, have multiplied there into numbers probably much exceeding those extant in their native lands; indeed, when we contemplate our own race, and our particular stock, taking such recent but dominating possession of this New World; when we consider how the indigenous flora of islands generally succumbs to the foreigners which come in the train of man; and that most weeds (i.e., the prepotent plants in open soil) of all temperate climates are not "to the manner born," but are self-invited intruders--we must needs abandon the notion of any primordial and absolute adaptation of plants and animals to their habitats, which may stand in lieu of explanation, and so preclude our inquiring any further. The harmony of Nature and its admirable perfection need not be regarded as inflexible and changeless. Nor need Nature be likened to a statue, or a cast in rigid bronze, but rather to an organism, with play and adaptability of parts, and life and even soul informing the whole. Under the former view Nature 174 would be "the faultless monster which the world ne'er saw," but inscrutable as the Sphinx, whom it were vain, or worse, to question of the whence and whither. Under the other, the perfection of Nature, if relative, is multifarious and ever renewed; and much that is enigmatical now may find explanation in some record of the past. That the two species of redwood we are contemplating originated as they are and where they are, and for the part they are now playing, is, to say the least, not a scientific supposition, nor in any sense a probable one. Nor is it more likely that they are destined to play a conspicuous part in the future, or that they would have done so, even if the Indian's fires and the white man's axe had spared them. The redwood of the coast (Sequoia sempervirens) had the stronger hold upon existence, forming as it did large forests throughout a narrow belt about three hundred miles in length, and being so tenacious of life that every large stump sprouts into a copse. But it does not pass the bay of Monterey, nor cross the line of Oregon, although so grandly developed not far below it. The more remarkable Sequoia gigantea of the Sierra exists in numbers so limited that the separate groves may be reckoned upon the fingers, and the trees of most of them have been counted, except near their southern limit, where they are said to be more copious. A species limited in individuals holds its existence by a precarious tenure; and this has a foothold only in a few sheltered spots, of a happy mean in temperature, and locally favored with moisture in summer. Even there, for some reason or other, the pines with which they are associated (Pinus Lambertiana and P. ponderosa), the firs (Abies grandis and A. amabilis), and even the incense-cedar (Libocedrus decurrens), possess a great advantage, and, though they strive in vain to emulate their size, wholly overpower the Sequoias in numbers. "To him that hath shall be given." The force of numbers eventually wins. At least in the commonly-visited groves Sequoia gigantea is invested in its SEQUOIA AND ITS HISTORY 175 last stronghold, can neither advance into more exposed positions above, nor fall back into drier and barer ground below, nor hold its own in the long-run where it is, under present conditions; and a little further drying of the climate, which must once have been much moister than now, would precipitate its doom. Whatever the individual longevity, certain if not speedy is the decline of a race in which a high death-rate afflicts the young. Seedlings of the big trees occur not rarely, indeed, but in meagre proportion to those of associated trees; T small indeed is the chance that any of these will attain to "the days of the years of their fathers." "Few and evil" are .: the days of all the forest likely to be, while man, both bar-barian and civilized, torments them with fires, fatal at once to seedlings, and at length to the aged also. The forests of California, proud as the State may be of them, are already too scanty and insufficient for her uses. Two lines, such as may be drawn with one sweep of a brush over the map, would cover them all. The coast redwood--the most important tree in California, although a million times more numerous than its relative of the Sierra--is too good to live long. Such is its value for lumber and its accessibility, that, judging the future by the past, it is not likely, in its primeval growth, to outlast its rarer fellow-species. Happily man preserves and disseminates as well as destroys. The species will doubtless be preserved to science, and for ornamental and other uses, in its own and other lands; and the more remarkable individuals of the present day are likely to be sedulously cared for, all the more so as they become scarce. Our third question remains to be answered: Have these famous Sequoias played in former times and upon a larger stage a more imposing part, of which the present is but the epilogue? We cannot gaze high up the huge and venerable trunks, which one crosses the continent to behold, without wishing that these patriarchs of the grove were able, like the 176 long-lived antediluvians of Scripture, to hand down to us, through a few generations, the traditions of centuries, and so tell us somewhat of the history of their race. Fifteen hundred annual layers have been counted, or satisfactorily made out, upon one or two fallen trunks. It is probable that close to the heart of some of the living trees may be found the circle that records the year of our Saviour's nativity. A few generations of such trees might carry the history a long way back. But the ground they stand upon, and the marks of very recent geological change and vicissitude in the region around, testify that not very many such generations can have flourished just there, at least in an unbroken series. When their site was covered by glaciers, these Sequoias must have occupied other stations, if, as there is reason to believe, they then existed in the land. I have said that the redwoods have no near relatives in the country of their abode, and none of their genus anywhere else. Perhaps something may be learned of their genealogy by inquiring of such relatives as they have. There are only two of any particular nearness of kin; and they are far away. One is the bald cypress, our Southern cypress, Taxodium, inhabiting the swamps of the Atlantic coast from Maryland to Texas, thence extending--with, probably, a specific difference--into Mexico. It is well known as one of the largest trees of our Atlantic forest-district, and, although it never--except perhaps in Mexico, and in rare instances--attains the portliness of its Western relatives, yet it may equal them in longevity. The other relative is Glyptostrobus, a sort of modified Taxodium, being about as much like our bald cypress as one species of redwood is like the other. Now, species of the same type, especially when few, and the type peculiar, are, in a general way, associated geographically, i.e., inhabit the same country, or (in a large sense) the same region. Where it is not so, where near relatives are separated, there is usually something to be explained. Here is an instance. stance. These four trees, sole representatives of their tribe, dwell almost in three separate quarters of the world: the two redwoods in California, the bald cypress in Atlantic North America, its near relative, Glyptostrobus, in China. It was not always so. In the Tertiary period, the geological botanists assure us, our own very Taxodium or bald cypress, and a Glyptostrobus, exceedingly like the present Chinese tree, and more than one Sequoia, coexisted in a fourth quarter of the globe, viz., in Europe! This brings up the question, Is it possible to bridge over these four wide intervals of space and the much vaster interval of time, so as to bring these extraordinarily separated relatives into connection? The evidence which may be brought to bear upon this question is various and widely scattered. I bespeak your patience while I endeavor to bring together, in an abstract, the most important points of it. Some interesting facts may come out by comparing generally the botany of the three remote regions, each of which is the sole home of one of these genera, i.e., Sequoia in California, Taxodium in the Atlantic United States,[V-1] and Glyptostrobus in China, which compose the whole of the peculiar tribe under consideration. Note then, first, that there is another set of three or four peculiar trees, in this case of the yew family, which has just the same peculiar distribution, and which therefore may have the same explanation, whatever that explanation be. The genus Torreya, which commemorates our botanical Nestor and a former president of this Association, Dr. Torrey, was founded upon a tree rather lately discovered (that is, about thirty-five years ago) in Northern Florida. It is a noble, yew like tree, and very local, being, so far as known, nearly confined to a few miles along the shores of a single river. It seems as if it had somehow been crowded down out of the Alleghanies into its present limited southern quarters; for in cultivation it evinces a northern hardiness. Now, another species of Torreya is a characteristic tree of Japan; and one very like it, if not the same, inhabits the mountains of Northern China--belongs, therefore, to the Eastern Asiatic temperate region, of which Northern China is a part, and Japan, as we shall see, the portion most interesting to us. There is only one more species of Torreya, and that is a companion of the redwoods in California. It is the tree locally known under the name of the California nutmeg. Here are three or four near brethren, species of the same genus, known nowhere else than in these three habitats. Moreover, the Torreya of Florida is associated with a yew; and the trees of this grove are the only yew-trees of Eastern North America; for the yew of our Northern woods is a decumbent shrub. A yew-tree, perhaps the same, is found with Taxodium in the temperate parts of Mexico. The only other yews in America grow with the redwoods and the other Torreya in California, and extend northward into Oregon. Yews are also associated with Torreya in Japan; and they extend westward through Mantchooria and the Himalayas to Western Europe, and even to the Azores Islands, where occurs the common yew of the Old World. So we have three groups of coniferous trees which agree in this peculiar geographical distribution, with, however, a notable extension of range in the case of the yew: 1. The redwoods, and their relatives, Taxodium and Glyptostrobus, which differ so as to constitute a genus for each of the three regions; 2. The Torreyas, more nearly akin, merely a different species in each region; 3. The yews, still more closely related while more widely disseminated, of which it is yet uncertain whether they constitute seven, five, three, or only one species. Opinions differ, and can hardly be brought to any decisive test. However it be determined, it may still be said that the extreme differences among the yews do not surpass those of the recognized variations of the European yew, the cultivated races included. It appears to me that these several instances all raise the very same question, only with different degrees of emphasis, and, if to be explained at all, will have the same kind of explanation. Continuing the comparison between the three regions with which we are concerned, we note that each has its own species of pines, firs, larches, etc., and of a few deciduous-leaved trees, such as oaks and maples; all of which have no peculiar significance for the present purpose, because they are of genera which are common all round the northern hemisphere. Leaving these out of view, the noticeable point is that the vegetation of California is most strikingly unlike that of the Atlantic United States. They possess some plants, and some peculiarly American plants, in common--enough to show, as I imagine, that the difficulty was not in the getting from the one district to the other, or into both from a common source, but in abiding there. The primordially unbroken forest of Atlantic North America, nourished by rainfall distributed throughout the year, is widely separated from the western region of sparse and discontinuous tree-belts of the same latitude on the western side of the continent (where summer rain is wanting, or nearly so), by immense treeless plains and plateaux of more or less aridity, traversed by longitudinal mountain-ranges of a similar character. Their nearest approach is at the north, in the latitude of Lake Superior, where, on a more rainy line, trees of the Atlantic forest and that of Oregon may be said to intermix. The change of species and of the aspect of vegetation in crossing, say on the forty-seventh parallel, is slight in comparison with that on the thirty-seventh or near it. Confining our attention to the lower latitude, and under the exceptions already specially noted, we may say that almost every characteristic form in the vegetation of the Atlantic States is wanting in California, and the characteristic plants and trees of California are wanting here. California has no magnolia nor tulip trees, nor star-anise tree; no so-called papaw (Asimina); no barberry of the common single-leaved sort; no Podophyllum or other of the peculiar associated genera; no nelumbo nor white water-lily; no prickly ash nor sumach; no loblolly-bay nor Stuartia; no basswood nor linden-trees; neither locust, honey-locust, coffeetrees (Gymnocladus) nor yellow-wood (Cladrastis); nothing answering to Hydrangea or witch-hazel, to gum-trees (Nyssa and Liquidambar), Viburnum or Diervilla; it has few asters and golden-rods; no lobelias; no huckleberries and hardly any blueberries; no Epigaea, charm of our earliest Eastern spring, tempering an icy April wind with a delicious wild fragrance; no Kalmia nor Clethra, nor holly, nor persimmon; no catalpa-tree, nor trumpet-creeper (Tecoma); nothing answering to sassafras, nor to benzoin-tree, nor to hickory; neither mulberry nor elm; no beech, true chestnut, hornbeam, nor iron-wood, nor a proper birch-tree; and the enumeration might be continued very much further by naming herbaceous plants and others familiar only to botanists. In their place California is filled with plants of other types--trees, shrubs, and herbs, of which I will only remark that they are, with one or two exceptions, as different from the plants of the Eastern Asiatic region with which we are concerned (Japan, China, and Mantchooria), as they are from those of Atlantic North America. Their near relatives, when they have any in other lands, are mostly southward, on the Mexican plateau, or many as far south as Chili. The same may be said of the plants of the intervening great Plains, except that northward in the subsaline vegetation there are some close alliances with the flora of the steppes of Siberia. And 181 along the crests of high mountain-ranges the Arctic-Alpine . flora has sent southward more or less numerous representatives through the whole length of the country. If we now compare, as to their flora generally, the Atlantic United States with Japan, Mantchooria, and Northern China--i.e., Eastern North America with Eastern North Asia, half the earth's circumference apart--we find an astonishing similarity. The larger part of the genera of our own region, which I have enumerated as wanting in California, are present in Japan or Mantchooria, along with many other peculiar plants, divided between the two. There are plants enough of the one region which have no representatives in the other. There are types which appear to have reached the Atlantic States from the south; and there is a larger infusion of subtropical Asiatic types into temperate China and Japan; among these there is no relationship between the two countries to speak of. There are also, as I have already said, no small number of genera and some species which, being common all round or partly round the northern temperate zone, have no special significance because of their occurrence in these two antipodal floras, although they have testimony to bear upon the general question of geographical distribution. The point to be remarked is, that many, or even most, of the genera and species which are peculiar to North America as compared with Europe, and largely peculiar to Atlantic North America as compared with the Californian region, are also represented in Japan and Mantchooria, either by identical or by closely-similar forms! The same rule holds on a more northward line, although not so strikingly. If we compare the plants, say of New England and Pennsylvania (latitude 450_470), with those of Oregon, and then with those of Northeastern Asia, we shall find many of our own curiously repeated in the latter, while only a small number of them can be traced along the route even so far as the western slope of the Rocky Mountains. And these repetitions of East American types in Japan 182 and neighboring districts are in all degrees of likeness. Sometimes the one is undistinguishable from the other; sometimes there is a difference of aspect, but hardly of tangible character; sometimes the two would be termed marked varieties if they grew naturally in the same forest or in the same region; sometimes they are what the botanist calls representative species, the one answering closely to the other, but with some differences regarded as specific; sometimes the two are merely of the same genus, or not quite that, but of a single or very few species in each country; in which case the point which interests us is, that this peculiar limited type should occur in two antipodal places, and nowhere else. It would be tedious, and, except to botanists, abstruse, to enumerate instances; yet the whole strength of the case depends upon the number of such instances. I propose therefore, if the Association does me the honor to print this discourse, to append in a note a list of the more remarkable ones.[V-2] But I would here mention certain cases as specimens. Our Rhus Toxicodendron, or poison-ivy, is very exactly repeated in Japan, but is found in no other part of the world, although a species much like it abounds in California. Our other poisonous Rhus (R. venenata), commonly called poison-dogwood, is in no way represented in Western America, but has so close an analogue in Japan that the two were taken for the same by Thunberg and Linnaeus, who called them both R. vernix. Our northern fox-grape, Vitis Labrusca, is wholly confined to the Atlantic States, except that it reappears in Japan and that region. The original Wistaria is a woody leguminous climber with showy blossoms, native to the middle Atlantic States; the other species, which we so much prize in cultivation, W. Sinensis, is from China, as its name denotes, or perhaps only from Japan, where it is certainly indigenous. Our yellow-wood (Cladrastis) inhabits a very limited district on the western slope of the Alleghanies. Its only and very near relative, Maackia, is confined to Mantchooria. The Hydrangeas have some species in our Alleghany region: all the rest belong to the Chino-Japanese region and its continuation westward. The same may be said of Philadelphus, except that there are one or two mostly very similar species in California and Oregon. Our May-flower (Epigaea) and our creeping snowberry, otherwise peculiar to Atlantic North America, recur in Japan. Our blue cohosh (Caulophyllum) is confined to the woods of the Atlantic States, but has lately been discovered in Japan. A peculiar relative of it, Diphylleia, confined to the higher Alleghanies, is also repeated in Japan, with a slight difference, so that it may barely be distinguished as another : species. Another relative is our twin-leaf (Jeffersonia) of the Alleghany region alone: a second species has lately turned up in Mantchooria. A relative of this is Podophyllum, our mandrake, a common inhabitant of the Atlantic United States, but found nowhere else. There is one other species of it, and that is in the Himalayas. Here are four most peculiar genera of one family, each of a single species in the Atlantic United States, which are duplicated on the other side of the world, either in identical or almost identical species, or in an analogous species, while nothing else of the kind is known in any other part of the world. I ought not to omit ginseng, the root so prized by the Chinese, which they obtain from their northern provinces and Mantchooria, and which is now known to inhabit Corea and Northern Japan. The Jesuit Fathers identified the plant in Canada and the Atlantic States, brought over the Chinese name by which we know it, and established the trade in it, which was for many years most profitable. The exportation of ginseng to China probably has not yet entirely ceased. Whether the Asiatic and the Atlantic American ginsengs are to be regarded as of the same species or not is somewhat uncertain, but they are hardly, if at all, distinguishable. There is a shrub, Elliottia, which is so rare and local that it is known only at two stations on the Savannah River in Georgia. It is of peculiar structure, and was without near relative until one was lately discovered in Japan (Tripetaleia), so like it as hardly to be distinguishable except by having the parts of the blossom in threes instead of fours--a difference not uncommon in the same genus, or even in the same species. Suppose Elliottia had happened to be collected only once, a good while ago, and all knowledge of the limited and obscure locality were lost; and meanwhile the Japanese form came to be known. Such a case would be parallel with an actual one. A specimen of a peculiar plant (Shortia galacifolia) was detected in the herbarium of the elder Michaux, who collected it (as his autograph ticket shows) somewhere in the high Alleghany Mountains, more than eighty years ago. No one has seen the living plant since or knows where to find it, if haply it still flourishes in some secluded spot. At length it is found in Japan; and I had the satisfaction of making the identification.[V-3] A relative is also known in Japan; and a less near one has just been detected in Thibet. Whether the Japanese and the Alleghanian plants are exactly the same or not, it needs complete specimens of the two to settle. So far as we know, they are just alike; and, even if some difference were discerned between them, it would not appreciably alter the question as to how such a result came to pass. Each and every one of the analogous cases I have been detailing--and very many more could be mentioned--raises the same question, and would be satisfied with the same answer. These singular relations attracted my curiosity early in the course of my botanical studies, when comparatively few of them were known, and my serious attention in later years, when I had numerous and new Japanese plants to study in the collections made, by Messrs. Williams and Morrow, during Commodore Perry's visit in 1853, and especially, by Mr. Charles Wright, of Commodore Rodgers's expedition in 1855. I then discussed this subject somewhat fully, and tabulated the facts within my reach.[V-4] This was before Heer had developed the rich fossil botany of the arctic zone, before the immense antiquity of existing species of plants was recognized, and before the publication of Darwin's now famous volume on the "Origin of Species" had introduced and familiarized the scientific world with those now current ideas respecting the history and vicissitudes of species with which I attempted to deal in a moderate and feeble way. My speculation was based upon the former glaciation of the northern temperate zone, and the inference of a warmer period preceding and perhaps following. I considered that our own present vegetation, or its proximate ancestry, must have occupied the arctic and subarctic regions in pliocene times, and that it had been gradually pushed southward as the temperature lowered and the glaciation advanced, even beyond its present habitation; that plants of the same stock and kindred, probably ranging round the arctic zone as the present arctic species do, made their forced migration southward upon widely different longitudes, and receded more or less as the climate grew warmer; that the general difference of climate which marks the eastern and the western sides of the continents--the one extreme, the other mean--was doubtless even then established, so that the same species and the same sorts of species would be likely to secure and retain foothold in the similar climates of Japan and the Atlantic United States, but not in intermediate regions of different distribution of heat and moisture; so that different species of the same genus, as in Torreya, or different genera of the same group, as redwood, Taxodium, and Glyptostrobus, or different associations of forest-trees, might establish themselves each in the region best suited to the particular requirements, while they would fail to do so in any other. These views implied that the sources of our actual vegetation and the explanation of these peculiarities were to be sought in, and presupposed, an ancestry in pliocene or earlier times, occupying the higher northern regions. And it was thought that the occurrence of peculiar North American genera in Europe in the Tertiary period (such as Taxodium, Carya, Liquidambar, sassafras, Negundo, etc.) might be best explained on the assumption of early interchange and diffusion through North Asia, rather than by that of the fabled Atlantis. The hypothesis supposed a gradual modification of species in different directions under altering conditions, at least to the extent of producing varieties, sub-species, and representative species, as they may be variously regarded; likewise the single and local origination of each type, which is now almost universally taken for granted. The remarkable facts in regard to the Eastern American and Asiatic floras which these speculations were to explain have since increased in number, especially through the admirable collections of Dr. Maximowicz in Japan and adjacent countries, and the critical comparisons he has made and is still engaged upon. I am bound to state that, in a recent general work[V-5] by a distinguished European botanist, Prof. Grisebach, of Jotting, these facts have been emptied of all special significance, and the relations between the Japanese and the Atlantic United States flora declared to be no more intimate than might be expected from the situation, climate, and present opportunity of interchange. This extraordinary conclusion is reached by regarding as distinct species all the plants common to both countries between which any differences have been discerned, although such differences would probably count for little if the two inhabited the same country, thus transferring many of my list of identical to that of representative species; and then by simply eliminating from consideration the whole array of representative species, i.e., all cases in which the Japanese and the American plant are not exactly alike. As if, by pronouncing the cabalistic word species, the question were settled, or rather the greater part of it remanded out of the domain of science; as if, while complete identity of forms implied community of origin, anything short of it carried no presumption of the kind; so leaving all these singular duplicates to be wondered at, indeed, but wholly beyond the reach of inquiry. Now, the only known cause of such likeness is inheritance; and as all transmission of likeness is with some difference in individuals, and as changed conditions have resulted, as is well known, in very considerable differences, it seems to me that, if the high antiquity of our actual vegetation could be rendered probable, not to say certain, and the former habitation of any of our species or of very near relatives of them in high northern regions could be ascertained, my whole case would be made out. The needful facts, of which I was ignorant when my essay was published, have now been for some years made known--thanks, mainly, to the researches of Heer upon ample collections of arctic fossil plants. These are confirmed and extended by new investigations, by Heer and Lesquereux, the results of which have been indicated to me by the latter.[V-6] The Taxodium, which everywhere abounds in the miocene formations in Europe, has been specifically identified, first by Goeppert, then by Heer, with our common cypress of the Southern States. It has been found fossil in Spitzbergen, Greenland, and Alaska--in the latter country along with the remains of another form, distinguishable, but very like the common species; and this has been identified by Lesquereux in the miocene of the Rocky Mountains. So there is one species of tree which has come down essentially unchanged from the Tertiary period, which for a long while inhabited both Europe and North America, and also, at some part of the period, the region which geographically connects the two (once doubtless much more closely than now), but which has survived only in the Atlantic United States and Mexico. The same Sequoia which abounds in the same miocene formations in Northern Europe has been abundantly found in those of Iceland, Spitzbergen, Greenland, Mackenzie River, and Alaska. It is named S. Langsdorfii, but is pronounced to be very much like S. sempervirens, our living redwood of the Californian coast, and to be the ancient representative of it. Fossil specimens of a similar, if not the same, species have recently been detected in the Rocky Mountains by Hayden, and determined by our eminent palaeontological botanist, Lesquereux; and he assures me that he has the common redwood itself from Oregon in a deposit of tertiary age. Another Sequoia (S. Sternbergii), discovered in miocene deposits in Greenland, is pronounced to be the representative of S. gigantea, the big tree of the Californian Sierra. If the Taxodium of the tertiary time in Europe and throughout the arctic regions is the ancestor of our present bald cypress--which is assumed in regarding them as specifically identical-- then I think we may, with our present light, fairly assume that the two redwoods of California are the direct or collateral descendants of the two ancient species which so closely resemble them. The forests of the arctic zone in tertiary times contained at least three other species of Sequoia, as determined by their remains, one of which, from Spitzbergen, also much resembles the common redwood of California. Another, "which appears to have been the commonest coniferous tree on Disco," was common in England and some other parts of Europe. So the Sequoias, now remarkable for their restricted station and numbers, as well as for their extraordinary size, are of an ancient stock; their ancestors and kindred formed a large part of the forests which flourished throughout the polar regions, now desolate and ice-clad, and which extended into low latitudes in Europe. On this continent one species, at least, had reached to the vicinity of its present habitat before the glaciation of the region. Among the fossil specimens already found in California, but which our trustworthy palaeontological botanist has not yet had time to examine, we may expect to find evidence of the early arrival of these two redwoods upon the ground which they now, after much vicissitude, scantily occupy. Differences of climate, or circumstances of migration, or both, must have determined the survival of Sequoia upon the Pacific, and of Taxodium upon the Atlantic coast. And still the redwoods will not stand in the east, nor could our Taxodium find a congenial station in California. Both have probably had their opportunity in the olden time, and failed. As to the remaining near relative of Sequoia, the Chinese Glyptostrobus, a species of it, and its veritable representative, was contemporaneous with Sequoia and Taxodium, not only in temperate Europe, but throughout the arctic regions from Greenland to Alaska. According to Newberry, it was abundantly represented in the miocene flora of the temperate zone of our own continent, from Nebraska to the Pacific. Very similar would seem to have been the fate of a more familiar gymnospermous tree, the Gingko or Salisburia. It is now indigenous to Japan only. Its ancestor, as we may fairly call it--since, according to Heer, "it corresponds so entirely with the living species that it can scarcely be separated from it"--once inhabited Northern Europe and the whole arctic region round to Alaska, and had even a representative farther south, in our Rocky Mountain district. For some reason, this and Glyptostrobus survive only on the shores of Eastern Asia. Libocedrus, on the other hand, appears to have cast in its lot with the Sequoias. Two species, according to Heer, were with them in Spitzbergen. L. decurrens, the incense cedar, is one of the noblest associates of the present redwoods. But all the rest are in the southern hemisphere, two at the southern extremity of the Andes, two in the South-Sea Islands. It is only by bold and far-reaching suppositions that they can be geographically associated. The genealogy of the Torreyas is still wholly obscure; yet it is not unlikely that the yew-like trees, named Taxites, which flourished with the Sequoias in the tertiary arctic forests, are the remote ancestors of the three species of Torreya, now severally in Florida, in California, and in Japan. As to the pines and firs, these were more numerously associated with the ancient Sequoias of the polar forests than with their present representatives, but in different species, apparently more like those of Eastern than of Western North America. They must have encircled the polar zone then, as they encircle the present temperate zone now. I must refrain from all enumeration of the angiospermous or ordinary deciduous trees and shrubs, which are now known, by their fossil remains, to have flourished throughout the polar regions when Greenland better deserved its name and enjoyed the present climate of New England and New Jersey. Then Greenland and the rest of the north abounded with oaks, representing the several groups of species which now inhabit both our Eastern and Western forest districts; several poplars, one very like our balsam poplar or balm-of-Gilead tree; more beeches than there are now, a hornbeam, and a hop-hornbeam, some birches, a persimmon, and a planer-tree, near representatives of those of the Old World, at least of Asia, as well as of Atlantic North America, but all wanting in California; one Juglans like the walnut of the Old World, and another like our black walnut; two or three grapevines, one near our Southern fox grape or muscadine, another near our Northern frostgrape; a Tilia, very like our basswood of the Atlantic States only; a Liquidambar; a magnolia, which recalls our M. grandiflora; a Liriodendron, sole representative of our tulip-tree; and a sassafras, very like the living tree. Most of these, it will be noticed, have their nearest or their only living representatives in the Atlantic States, and when elsewhere, mainly in Eastern Asia. Several of them, or of species like them, have been detected in our tertiary deposits, west of the Mississippi, by Newberry and Lesquereux. Herbaceous plants, as it happens, are rarely preserved in a fossil state, else they would probably supply additional testimony to the antiquity of our existing vegetation, its wide diffusion over the northern and now frigid zone, and its enforced migration under changes of climate.[V-7] Concluding, then, as we must, that our existing vegetation is a continuation of that of the tertiary period, may we suppose that it absolutely originated then? Evidently not. The preceding Cretaceous period has furnished to Carruthers in Europe a fossil fruit like that of the Sequoia gigantea of the famous groves, associated with pines of the same character as those that accompany the present tree; has furnished to Heer, from Greenland, two more Sequoias, one of them identical with a tertiary species, and one nearly allied to Sequoia Langsdorfii, which in turn is a probable ancestor of the common California redwood; has furnished to Newberry and Lesquereux in North America the remains of another ancient Sequoia, a Glyptostrobus, a Liquidambar which well represents our sweet-gum-tree, oaks analogous to living ones, leaves of a plane-tree, which are also in the Tertiary, and are scarcely distinguishable from our own Platanus occidentalis, of a magnolia and a tulip-tree, and "of a sassafras undistinguishable from our living species." I need not continue the enumeration. Suffice it to say that the facts justify the conclusion which Lesquereux--a scrupulous investigator--has already announced: that "the essential types of our actual flora are marked in the Cretaceous period, and have come to us after passing, without notable changes, through the Tertiary formations of our continent." According to these views, as regards plants at least, the adaptation to successive times and changed conditions has been maintained, not by absolute renewals, but by gradual modifications. I, for one, cannot doubt that the present existing species are the lineal successors of those that garnished the earth in the old time before them, and that they were as well adapted to their surroundings then, as those which flourish and bloom around us are to their conditions now. Order and exquisite adaptation did not wait for man's coming, nor were they ever stereotyped. Organic Nature--by which I mean the system and totality of living things, and their adaptation to each other and to the world--with all its apparent and indeed real stability, should be likened, not to the ocean, which varies only by tidal oscillations from a fixed level to which it is always returning, but rather to a river, so vast that we can neither discern its shores nor reach its sources, whose onward flow is not less actual because too slow to be observed by the ephemerae which hover over its surface, or are borne upon its bosom. Such ideas as these, though still repugnant to some, and not long since to many, have so possessed the minds of the naturalists of the present day that hardly a discourse can be pronounced or an investigation prosecuted without reference to them. I suppose that the views here taken are little, if at all, in advance of the average scientific mind of the day. I cannot regard them as less noble than those which they are succeeding. An able philosophical writer, Miss Frances Power Cobbe, has recently and truthfully said:[V-8] "It is a singular fact that, when we can find out how anything is done, our first conclusion seems to be that God did not do it. No matter how wonderful, how beautiful, how intimately complex and delicate has been the machinery which has worked, perhaps for centuries, perhaps for millions of ages, to bring about some beneficent result, if we can but catch a glimpse of the wheels its divine character disappears." I agree with the writer that this first conclusion is premature and unworthy--I will add, deplorable. Through what faults or infirmities of dogmatism on the one hand, and skepticism on the other, it came to be so thought, we need not here consider. Let us hope, and I confidently expect, that it is not to last; that the religious faith which survived without a shock the notion of the fixity of the earth itself may equally outlast the notion of the fixity of the species which inhabit it; that, in the future even more than in the past, faith in an order, which is the basis of science, will not--as it cannot reasonably--be dissevered from faith in an Ordainer, which is the basis of religion. VI THE ATTITUDE OF WORKING NATURALISTS TOWARD DARWINISM [VI-1] (The Nation, October 16, 1873) That homely adage, "What is one man's meat is another man's poison," comes to mind when we consider with what different eyes different naturalists look upon the hypothesis of the derivative origin of actual specific forms, since Mr. Darwin gave it vogue and vigor and a raison d'être for the present day. This latter he did, not only by bringing forward a vera causa in the survival of the fittest under changing circumstances--about which the question among naturalists mainly is how much it will explain, some allowing it a restricted, others an unlimited operation--but also by showing that the theory may be made to do work, may shape and direct investigations, the results of which must in time tell us whether the theory is likely to hold good or not. If the hypothesis of natural selection and the things thereto appertaining had not been capable of being put to useful work, although, like the "Vestiges of the Natural History of Creation," it might have made no little noise in the world, it would hardly have engaged the attention of working naturalists as it has done. We have no idea even of opening the question as to what work the Darwinian theory has incited, and in what way the work done has reacted upon the theory; and least of all do we like to meddle with the polemical literature of the subject, already so voluminous that the German bibliographers and booksellers make a separate class of it. But two or three treatises before us, of a minor or incidental sort, suggest a remark or two upon the attitude of mind toward evolutionary theories taken by some of the working naturalists. Mr. Darwin's own expectation, that his new presentation of the subject would have little or no effect upon those who had already reached middle-age, has--out of Paris--not been fulfilled. There are, indeed, one or two who have thought it their duty to denounce the theory as morally dangerous, as well as scientifically baseless; a recent instance of the sort we may have to consider further on. Others, like the youth at the river's bank, have been waiting in confident expectation of seeing the current run itself dry. On the other hand, a notable proportion of the more active-minded naturalists had already come to doubt the received doctrine of the entire fixity of species, and still more that of their independent and supernatural origination. While their systematic work all proceeded implicitly upon the hypothesis of the independence and entire permanence of species, they were perceiving more or less clearly that the whole question was inevitably to be mooted again, and so were prepared to give the alternative hypothesis a dispassionate consideration. The veteran Lyell set an early example, and, on a reconsideration of the whole question, wrote anew his famous chapter and reversed his former and weighty opinion. Owen, still earlier, signified his adhesion to the doctrine of derivation in some form, but apparently upon general, speculative grounds; for he repudiated natural selection, and offered no other natural solution of the mystery of the orderly incoming of cognate forms. As examples of the effect of Darwin's "Origin of Species" upon the minds of naturalists who are no longer young, and whose prepossessions, even more than Lyell's, were likely to bias them against the new doctrine, two from the botanical side are brought to our notice through recent miscellaneous writings which are now before us.[VI-2] Before the publication of Darwin's first volume, M. Alphonse de Candolle had summed up the result of his studies in this regard, in the final chapter of his classical "Geographie Botanique Raisonnee," in the conclusion, that existing vegetation must be regarded as the continuation, through many geological and geographical changes, of the anterior vegetations of the world; and that, consequently, the present distribution of species is explicable only in the light of their geological history. He surmised that, notwithstanding the general stability of forms, certain species or quasi-species might have originated through diversification under geographical isolation. But, on the other hand, he was still disposed to admit that even the same species might have originated independently in two or more different regions of the world; and he declined, as unpractical and unavailing, all attempts to apply hypotheses to the elucidation of the origin of species. Soon after Darwin's book appeared, De Candolle had occasion to study systematically a large and wide-spread genus-- that of the oak. Investigating it under the new light of natural selection, he came to the conclusion that the existing oaks are all descendants of earlier forms, and that no clear line can be drawn between the diversification whic h has resulted in species and that which is exhibited in races and minor varieties. And now, in the introductory chapter of the volume of essays before us, he informs us that the idea which pervades them all, and in some sort connects very diverse topics, is that of considering this principle of selection. Of the principle itself, he remarks that it is neither a theory nor an hypothesis, but the expression of a necessary fact; that to deny it is very much like denying that round stones will roll downhill faster and farther than flat ones; and that the question of the present day in natural history is not whether there be natural selection, or even whether forms are derived from other forms, but to comprehend how, in what proportions, and by what means hereditary deviations take place, and in what ways an inevitable selection takes effect upon these. In two of these essays natural selection is directly discussed in its application to the human race; the larger one dealing ably with the whole subject, and with results at first view seemingly in a great degree negative, but yet showing that the supposed "failure of natural selection in the case of man" was an unwarrantable conclusion from too limited a view of a very complicated question. The article abounds in acute and fertile suggestions, and its closing chapter, "on the probable future of the human species" under the laws of selection, is highly interesting and noteworthy. The other and shorter essay discusses a special point, and brings out a corollary of the law of heredity which may not have been thought of before, but which is perfectly clear as soon as it is stated. It explains at once why contagious or epidemic diseases are most fatal at their first appearance, and less so afterward: not by the dying out of a virus--for, when the disease reaches a new population, it is as virulent as ever (as, for instance, the smallpox among the Indians)--but by the selection of a race less subject to attack through the destruction of those that were more so, and the inheritance of the comparative immunity by the children and the grandchildren of the survivors; and how this immunity itself, causing the particular disease to become rare, paves the way to a return of the original fatality; for the mass of such population, both in the present and the immediately preceding generation, not having been exposed to the infection, or but little exposed, has not undergone selection, and so in time the proportion liable to attack, or to fatal attack, gets to be as large as ever. The greater the fatality, especially in the population under marriageable age, the more favorable the condition of the survivors; and, by the law of heredity, their children should share in the immunity. This explanation of the cause, or of one cause, of the return of pests at intervals no less applies to the diminution of the efficacy of remedies, and of preventive means, such as vaccination. When Jenner introduced vaccination, the small-pox in Europe and European colonies must have lost somewhat of its primitive intensity by the vigorous weeding out of the more susceptible through many generations. Upon the residue, vaccination was almost complete protection, and, being generally practised, small-pox consequently became rare. Selection thus ceasing to operate, a population arises which has not been exposed to the contagion, and of which a considerable proportion, under the common law of atavism, comes to be very much in the condition of a people invaded for the first time by the disease. To these, as we might expect, vaccination would prove a less safeguard than to their progenitors three or four generations before. Mr. Bentham is a veteran systematic botanist of the highest rank and widest knowledge. He had not, so far as we know, touched upon questions of origination in the ante-Darwinian era. The dozen of presidential addresses delivered at anniversary meetings of the Linnean Society, from his assumption of the chair in the year 1862 down to the current year--each devoted to some topic of interest--and his recent "Memoir on Compositae," summing up the general results of a revision of an order to which a full tenth of all higher plants belong, furnish apt examples both of cautious criticism, conditional assent (as becomes the inaugurator of the quantification of the predicate), and of fruitful application of the new views to various problems concerning the classification and geographical distribution of plants. In his hands the hypothesis is turned at once to practical use as an instrument of investigation, as a means of interrogating Nature. In the result, no doubt seems to be left upon the author's mind that the existing species of plants are the result of the differentiation of previous species, or at least that the derivative hypothesis is to be adopted as that which offers the most natural, if not the only, explanation of the problems concerned. Similar conclusions reached in this country, from a study of the relations of its present flora with that which in earlier ages occupied the arctic zone, might also be referred to. (See preceding article.) An excellent instance of the way in which the derivative hypothesis is practically applied in these days, by a zoologist, is before us in Prof. Flower's modest and admirable paper on the Ungulata, or hoofed animals, and their geological history. We refer to it here, not so much for the conclusions it reaches or suggests, as to commend the clearness and the impartiality of the handling, and the sobriety and moderation of the deductions. Confining himself "within the region of the known, it is shown that, at least in one group of animals, the facts which we have as yet acquired point to the former existence of various intermediate forms, so numerous that they go far to discredit the view of the sudden introduction of new species. . . . The modern forms are placed along lines which converge toward a common centre." The gaps between the existing forms of the odd-toed group of ungulates (of which horses, rhinoceroses, and tapirs, are the principal representatives) are most bridged over by palaeontology, and somewhat the same may be said of the even-toed group, to which the ruminants and the porcine genus belong. "Moreover, the lines of both groups to a certain extent approximate, but, within the limits of our knowledge, they do not meet. . - . Was the order according to which the introduction of new forms seems to have taken place since the Eocene then entirely changed, or did it continue as far back as the period when these lines would have been gradually fused in a common centre?" Facts like these, which suggest grave diversification under long lapse of time, are well supplemented by those which essentially demonstrate a slighter diversification of many species over a wide range of space; whether into species or races depends partly upon how the naturalist uses these terms, partly upon the extent of the observations, or luck in getting together intermediate forms. The researches of Prof. Baird upon the birds of this continent afford a good illustration. A great number of our birds which have been, and must needs have been, regarded as very distinct species, each mainly with its own geographical area, are found to mingle their characters along bordering lines; and the same kinds of differences (of coloration, form, or other) are found to prevail through the species of each region, thus impressing upon them a geographical facies. Upon a submergence of the continent, reducing these several regions to islands sufficiently separated, these forms would be unquestioned species. Considerations such as these, of which a few specimens have now been adduced (not general speculations, as the unscientific are apt to suppose), and trials of the new views to see how far they will explain the problems or collocate the facts they are severally dealing with, are what have mainly influenced working naturalists in the direction of the provisional acceptance of the derivative hypothesis. They leave to polemical speculators the fruitless discussion of the question whether all species came from one or two, or more; they are trying to grasp the thing by the near, not by the farther end, and to ascertain, first of all, whether it is probable or provable that present species are descendants of former ones which were like them, but less and less like them the farther back we go. And it is worth noting that they all seem to be utterly unconscious of wrong-doing. Their repugnance to novel hypotheses is only the natural and healthy one. A change of a wonted line of thought is not made without an effort, nor need be made without adequate occasion. Some courage was required of the man who first swallowed an oyster from its shell; and of most of us the snail would still demand more. As the unaccustomed food proves to be good and satisfying, and also harmless, we may come to like it. That, however, which many good and eminent naturalists find to be healthful and reasonable, and others innocuous, a few still regard as most unreasonable and harmful. At present, we call to mind only two who not only hold to the entire fixity of species as an axiom or a confirmed principle, but also as a dogma, and who maintain, either expressly or implicitly, that the logical antithesis to the creation of species as they are, is not by law (which implies intention), but by chance. A recent book by one of these naturalists, or rather, by a geologist of eminence, the "Story of the Earth and Man," by Dr. Dawson,4 is now before us. The title is too near that of Guyot's "Earth and Man," with the publication of which popular volume that distinguished physical naturalist commenced his career in this country; and such catch-titles are a sort of trade-mark. As to the nature and merits of Dr. Dawson's work, we have left ourselves space only to say: 1. That it is addressed ad populum, which renders it rather the more than less amenable to the criticisms we may be disposed to make upon it. 2. That the author is thoroughly convinced that no species or form deserving the name was ever derived from another, or originated from natural causes; and he maintains this doctrine with earnestness, much variety of argument and illustration, and no small ability; so that he may be taken as a representative of the view exactly opposed to that which is favored by those naturalists whose essays we have been considering--to whom, indeed, he stands in marked contrast in spirit and method, being greatly disposed to argue the question from the remote rather than the near end. 3. And finally, he has a conviction that the evolutionary doctrines of the day are not only untrue, but thoroughly bad and irreligious. This belief, and the natural anxiety with which he contemplates their prevalence, may excuse a certain vehemence and looseness of statement which were better avoided, as where the geologists of the day are said to be "broken up into bands of specialists, little better than scientific banditti, liable to be beaten in detail, and prone to commit outrages on common-sense and good taste which bring their otherwise good cause into disrepute;" and where he despairingly suggests that the prevalence of the doctrines he deprecates "seems to indicate that the accumulated facts of our age have gone altogether beyond its capacity for generalization, and, but for the vigor which one sees everywhere, might be taken as an indication that the human mind has fallen into a state of senility." This is droll reading, when one considers that the "evolutionist" is the only sort of naturalist who has much occasion to employ his "capacity for generalization" upon "the accumulated facts" in their bearing upon the problem of the origin of species; since the "special creationist," who maintains that they were supernaturally originated just as they are, by the very terms of his doctrine places them out of the reach of scientific explanation. Again, when one reflects upon the new impetus which the derivative hypothesis has given to systematic natural history, and reads the declaration of a master in this department (the President of the Linnean Society) that Mr. Darwin "has in this nineteenth century brought about as great a revolution in the philosophic study of organic Nature as that which was effected in the previous century by the immortal Swede," it sounds oddly to hear from Dr. Dawson that "it obliterates the fine perception of differences from the mind of the naturalist, . . . . destroys the possibility of a philosophical classification, reducing all things to a mere series, and leads to a rapid decay in systematic zoology and botany, which is already very manifest among the disciples of Spencer and Darwin in England." So, also, "it removes from the study of Nature the ideas of final cause and purpose"--a sentence which reads curiously in the light of Darwin's special investigations, such as those upon the climbing of plants, the agency of insects in the fertilization of blossoms, and the like, which have brought back teleology to natural science, wedded to morphology and already fruitful of discoveries. The difficulty with Dr. Dawson here is (and it need not be underrated) that apparently he cannot as yet believe an adaptation, act, or result, to be purposed the apparatus of which is perfected or evolved in the course of Nature--a common but a crude state of mind on the part of those who believe that there is any originating purpose in the universe, and one which, we are sure, Dr. Dawson does not share as respects the material world until he reaches the organic kingdoms, and there, possibly, because he sees man at the head of them--of them, while above them. However that may be, the position which Dr. Dawson chooses to occupy is not left uncertain. After concluding, substantially, that those "evolutionists" who exclude design from Nature thereby exclude theism, which nobody will deny, he proceeds (on page 348) to give his opinion that the "evolutionism which professes to have a creator somewhere behind it . . . . is practically atheistic," and, "if possible, more unphilosophical than that which professes to set out from absolute and eternal nonentity," etc. There are some sentences which might lead one to suppose that Dr. Dawson himself admitted of an evolution "with a creator somewhere behind it." He offers it (page 320) as a permissible alternative that even man "has been created mediately by the operation of forces also concerned in the production of other animals;" concedes that a just theory "does not even exclude evolution or derivation, to a certain extent" (page 341); and that "a modern man of science" may safely hold "that all things have been produced by the Supreme Creative Will, acting either directly or through the agency of the forces and materials of his own production." Well, if this be so, why denounce the modern man of science so severely upon the other page merely for accepting the permission? At first sight, it might be thought that our author is exposing himself in one paragraph to a share of the condemnation which he deals out in the other. But the permitted views are nowhere adopted as his own; the evolution is elsewhere restricted within specific limits; and as to "mediate creation," although we cannot divine what is here meant by the term, there is reason to think it does not imply that the several species of a genus were mediately created, in a natural way, through the supernatural creation of a remote common ancestor. So that his own judgment in the matter is probably more correctly gathered from the extract above referred to and other similar deliverances, such as that in which he warns those who "endeavor to steer a middle course, and to maintain that the Creator has proceeded by way of evolution," that "the bare, hard logic of Spencer, the greatest English authority on evolution, leaves no place for this compromise, and shows that the theory, carried out to its legitimate consequences, excludes the knowledge of a Creator and the possibility of his work." Now, this is a dangerous line to take. Those defenders of the faith are more zealous than wise who must needs fire away in their catapults the very bastions of the citadel, in the defense of outposts that have become untenable. It has been and always will be possible to take an atheistic view of Nature, but far more reasonable from science and philosophy only to take a theistic view. Voltaire's saying here holds true: that if there were no God known, it would be necessary to invent one. It is the best, if not the only, hypothesis for the explanation of the facts. Whether the philosophy of Herbert Spencer (which is not to our liking) is here fairly presented, we have little occasion and no time to consider. In this regard, the close of his article No. 12 in the Contemporary Review shows, at least, his expectation of the entire permanence of our ideas of cause, origin, and religion, and predicts the futility of the expectation that the "religion of humanity" will be the religion of the future, or "can ever more than temporarily shut out the thought of a Power, of which humanity is but a small and fugitive product, which was in its course of ever-changing manifestation before humanity was, and will continue through other manifestations when humanity has ceased to be." If, on the one hand, the philosophy of the unknowable of the Infinite may be held in a merely quasi-theistic or even atheistic way, were not its ablest expounders and defenders Hamilton and Dean Mansel? One would sup-pose that Dr. Dawson might discern at least as much of a divine foundation to Nature as Herbert Spencer and Matthew Arnold; might recognize in this power that "something not ourselves that makes" for order as well as "for righteousness," and which he fitly terms supreme creative will; and, resting in this, endure with more complacency and faith the inevitable prevalence of evolutionary views which he is powerless to hinder. Although he cannot arrest the stream, he might do something toward keeping it in safe channels. We wished to say something about the way in which scientific men, worthy of the name, hold hypotheses and theories, using them for the purpose of investigation and the collocation of facts, yielding or withholding assent in degrees or provisionally, according to the amount of verification or likelihood, or holding it long in suspense; which is quite in contrast to that of amateurs and general speculators (not that we reckon Dr. Dawson in this class), whose assent or denial seldom waits, or endures qualification. With them it must on all occasions be yea or nay only, according to the letter of the Scriptural injunction, and whatsoever is less than this, or between the two, cometh of evil. VII EVOLUTION AND THEOLOGY [VII-1] (The Nation, January 15, 1874) The attitude of theologians toward doctrines of evolution, from the nebular hypothesis down to "Darwinism," is no less worthy of consideration, and hardly less diverse, than that of naturalists. But the topic, if pursued far, leads to questions too wide and deep for our handling here, except incidentally, in the brief notice which it falls in our way to take of the Rev. George Henslow's recent volume on "The Theory of Evolution of Living Things." This treatise is on the side of evolution, "considered as illustrative of the wisdom and beneficence of the Almighty." It was submitted for and received one of the Actonian prizes recently awarded by the Royal Institution of Great Britain. We gather that the staple of a part of it is worked up anew from some earlier discourses of the author upon "Genesis and Geology," "Science and Scripture not antagonistic," etc. In coupling with it a chapter of the second volume of Dr. Hodge's "Systematic Theology (Part II, Anthropology)," we call attention to a recent essay, by an able and veteran writer, on the other side of the question. As the two fairly enough represent the extremes of Christian thought upon the subject, it is convenient to review them in connection. Theologians have a short and easy, if not wholly satisfactory, way of refuting scientific doctrines which they object to, by pitting the authority or opinion of one savant against another. Already, amid the currents and eddies of modern opinion, the savants may enjoy the same advantage at the expense of the divines-- we mean, of course, on the scientific arena; for the mutual refutation of conflicting theologians on their own ground is no novelty. It is not by way of offset, however, that these divergent or contradictory views are here referred to, but only as an illustration of the fact that the divines are by no means all arrayed upon one side of the question in hand. And indeed, in the present transition period, until some one goes much deeper into the heart of the subject, as respects the relations of modern science to the foundations of religious belief, than either of these writers has done, it is as well that the weight of opinion should be distributed, even if only according to prepossessions, rather than that the whole stress should bear upon a single point, and that perhaps the authority of an interpretation of Scripture. A consensus of opinion upon Dr. Hodge's ground, for instance (although better guarded than that of Dr. Dawson), if it were still possible, would--to say the least--probably not at all help to reconcile science and religion. Therefore, it is not to be regretted that the diversities of view among accredited theologians and theological naturalists are about as wide and as equably distributed between the extremes (and we may add that the views themselves are quite as hypothetical) as those which prevail among the various naturalists and natural philosophers of the day. As a theologian, Mr. Henslow doubtless is not to be compared with the veteran professor at Princeton. On the other hand, he has the advantage of being a naturalist, and the son of a naturalist, as well as a clergyman: consequently he feels the full force of an array of facts in nature, and of the natural inferences from them, which the theological professor, from his Biblical standpoint, and on his implicit assumption that the Old Testament must needs teach true science, can hardly be expected to appreciate. Accordingly, a naturalist would be apt to say of Dr. Hodge's exposition of "theories of the universe" and kindred topics--and in no captious spirit-- that whether right or wrong on particular points, he is not often right or wrong in the way of a man of science. Probably from the lack of familiarity with prevalent ideas and their history, the theologians are apt to suppose that scientific men of the present day are taking up theories of evolution in pure wantonness or mere superfluity of naughtiness; that it would have been quite possible, as well as more proper, to leave all such matters alone. Quieta non movere is doubtless a wise rule upon such subjects, so long as it is fairly applicable. But the time for its application in respect to questions of the origin and relations of existing species has gone by. To ignore them is to imitate the foolish bird that seeks security by hiding its head in the sand. Moreover, the naturalists did not force these questions upon the world; but the world they study forced them upon the naturalists. How these questions of derivation came naturally and inevitably to be revived, how the cumulative probability that the existing are derived from preexisting forms impressed itself upon the minds of many naturalists and thinkers, Mr. Henslow has briefly explained in the introduction and illustrated in the succeeding chapters of the first part of his book. Science, he declares, has been compelled to take up the hypothesis of the evolution of living things as better explaining all the phenomena. In his opinion, it has become "infinitely more probable that all living and extinct beings have been developed or evolved by natural laws of generation from preexisting forms, than that they, with all their innumerable races and varieties, should owe their existences severally to Creative fiats." This doctrine, which even Dr. Hodge allows may possibly be held in a theistic sense, and which, as we suppose, is so held or viewed by a great proportion of the naturalists of our day, Mr. Henslow maintains is fully compatible with dogmatic as well as natural theology; that it explains moral anomalies, and accounts for the mixture of good and evil in the world, as well as for the merely relative perfection of things; and, finally, that "the whole scheme which God has framed for man's existence, from the first that was created to all eternity, collapses if the great law of evolution be suppressed." The second part of his book is occupied with a development of this line of argument. By this doctrine of evolution he does not mean the Darwinian hypothesis, although he accepts and includes this, looking upon natural selection as playing an important though not an unlimited part. He would be an evolutionist with Mivart and Owen and Argyll, even if he had not the vera causa which Darwin contributed to help him on. And, on rising to man, he takes ground with Wallace, saying: "I would wish to state distinctly that I do not at present see any evidence for believing in a gradual development of man from the lower animals by ordinary natural laws; that is, without some special interference, or, if it be preferred, some exceptional conditions which have thereby separated him from all other creatures, and placed him decidedly in advance of them all. On the other hand, it would be absurd to regard him as totally severed from them. It is the great degree of difference I would insist upon, bodily, mental, and spiritual, which precludes the idea of his having been evolved by exactly the same processes, and with the same limitations, as, for example, the horse from the palaeotherium." In illustrating this view, he reproduces Wallace's well-known points, and adds one or two of his own. We need not follow up his lines of argument. The essay, indeed, adds nothing material to the discussion of evolution, although it states one side of the case moderately well, as far as it goes. Dr. Hodge approaches the subject from the side of systematic theology, and considers it mainly in its bearing upon the origin and original state of man. Under each head he first lays down "the Scriptural doctrine," and then discusses "anti-Scriptural theories," which latter, under the first head, are the heathen doctrine of spontaneous generation, the modern doctrine of spontaneous generation, theories of development, specially that of Darwin, the atheistic character of the theory, etc. Although he admits "that there is a theistic and an atheistic form of the nebular hypothesis as to the origin of the universe, so there may be a theistic interpretation of the Darwinian theory," yet he contends that "the system is thoroughly atheistic," notwithstanding that the author "expressly acknowledges the existence of God." Curiously enough, the atheistic form of evolutionary hypotheses, or what he takes for such, is the only one which Dr. Hodge cares to examine. Even the "Reign of Law" theory, Owen's "purposive route of development and chance . . . . by virtue of inherent tendencies thereto," as well as other expositions of the general doctrine on a theistic basis, are barely mentioned without a word of comment, except, perhaps, a general "protest against the arraying of probabilities against the teachings of Scripture." Now, all former experience shows that it is neither safe nor wise to pronounce a whole system "thoroughly atheistic" which it is conceded may be held theistically, and which is likely to be largely held, if not to prevail, on scientific grounds. It may be well to remember that, "of the two great minds of the seventeenth century, Newton and Leibnitz, both profoundly religious as well as philosophical, one produced the theory of gravitation, the other objected to that theory that it was subversive of natural religion; also that the nebular hypothesis--a natural consequence of the theory of gravitation and of the subsequent progress of physical and astronomical discovery--has been denounced as atheistical even down to our day." It has now outlived anathema. It is undeniable that Mr. Darwin lays himself open to this kind of attack. The propounder of natural selection might be expected to make the most of the principle, and to overwork the law of parsimony in its behalf. And a system in which exquisite adaptation of means to ends, complicated inter-dependencies, and orderly sequences, appear as results instead of being introduced as factors, and in which special design is ignored in the particulars, must needs be obnoxious, unless guarded as we suppose Mr. Darwin might have guarded his. ground if he had chosen to do so. Our own opinion, after long consideration, is, that Mr. Darwin has no atheistical intent; and that, as respects the test question of design in Nature, his view may be made clear to the theological mind by likening it to that of the "believer in general but not in particular Providence." There is no need to cull passages in support of this interpretation from his various works while the author--the most candid of men--retains through all the editions of the "Origin of Species" the two mottoes from Whewell and Bishop Butler.[VII-2] The gist of the matter lies in the answer that should be rendered to the questions--1. Do order and useful-working collocation, pervading a system throughout all its parts, prove design? and, 2. Is such evidence negatived or invalidated by the probability that these particular collocations belong to lineal series of such in time, and diversified in the course of Nature--grown up, so to say, step by step? We do not use the terms "adaptation, "arrangement of means to ends," and the like, because they beg the question in stating it. Finally, ought not theologians to consider whether they have not already, in principle, conceded to the geologists and physicists all that they are asked to concede to the evolutionists; whether, indeed, the main natural theological difficulties which attend the doctrine of evolution--serious as they may be--are not virtually contained in the admission that there is a system of Nature with fixed laws. This, at least, we may say, that, under a system in which so much is done "by the establishment of general laws," it is legitimate for any one to prove, if he can, that any particular thing in the natural world is so done; and it is the proper business of scientific men to push their enquiries in this direction. It is beside the point for Dr. Hodge to object that, "from the nature of the case, what concerns the origin of things cannot be known except by a supernatural revelation;" that "science has to do with the facts and laws of Nature: here the question concerns the origin of such facts." For the very object of the evolutionists, and of Mr. Darwin in particular, is to remove these subjects from the category of origination, and to bring them under the domain of science by treating them as questions about how things go on, not how they began. Whether the succession of living forms on the earth is or is not among the facts and laws of Nature, is the very matter in controversy. Moreover, adds Dr. Hodge, it has been conceded that in this matter "proofs, in the proper sense of the word, are not to be had; we are beyond the region of demonstration, and have only probabilities to consider." Wherefore "Christians have a right to protest against the arraying of probabilities against the clear teachings of Scripture." The word is italicized, as if to intimate that probabilities have no claims which a theologian is bound to respect. As to arraying them against Scripture, there is nothing whatever in the essay referred to that justifies the statement. Indeed, no occasion offered; for the writer was discussing evolution in its relations to theism, not to Biblical theology, and probably would not be disposed to intermix arguments so different in kind as those from natural science and those from revelation. To pursue each independently, according to its own method, and then to compare the results, is thought to be the better mode of proceeding. The weighing of probabilities we had regarded as a proper exercise of the mind preparatory to forming an opinion. Probabilities, hypotheses, and even surmises, whatever they may be worth, are just what, as it seems to us, theologians ought not to be foremost in decrying, particularly those who deal with the reconciliation of science with Scripture, Genesis with geology, and the like. As soon as they go beyond the literal statements even of the English text, and enter into the details of the subject, they find ample occasion and display a special aptitude for producing and using them, not always with very satisfactory results. It is not, perhaps, for us to suggest that the theological army in the past has been too much encumbered with impedimenta for effective aggression in the conflict against atheistic tendencies in modern science; and that in resisting attack it has endeavored to hold too much ground, so wasting strength in the obstinate defense of positions which have become unimportant as well as untenable. Some of the arguments, as well as the guns, which well served a former generation, need to be replaced by others of longer range and greater penetration. If the theologians are slow to discern the signs and exigencies of the times, the religious philosophical naturalists must be looked to. Since the above remarks were written, Prof. Le Conte's "Religion and Science," just issued, has come to our hands. It is a series of nineteen Sunday lectures on the relation of natural and revealed religion, prepared in the first instance for a Bible-class of young men, his pupils in the University of South Carolina, repeated to similar classes at the University of California, and finally delivered to a larger and general audience. They are printed, the preface states, from a verbatim report, with only verbal alterations and corrections of some redundancies consequent upon extemporaneous delivery. They are not, we find, lectures on science under a religious aspect, but discourses upon Christian theology and its foundations from a scientific layman's point of view, with illustrations from his own lines of study. As the headings show, they cover, or, more correctly speaking, range over, almost the whole field of theological thought, beginning with the personality of Deity as revealed in Nature, the spiritual nature and attributes of Deity, and the incarnation; discussing by the way the general relations of theology to science, man, and his place in Nature; and ending with a discussion of predestination and free-will, and of prayer in relation to invariable law--all in a volume of three hundred and twenty-four duodecimo pages! And yet the author remarks that many important subjects have been omitted because he felt unable to present them in a satisfactory manner from a scientific point of view. We note, indeed, that one or two topics which would naturally come in his way--such, especially, as the relation of evolution to the human race--are somewhat conspicuously absent. That most of the momentous subjects which he takes up are treated discursively, and not exhaustively, is all the better for his readers. What they and we most want to know is, how these serious matters are viewed by an honest, enlightened, and devout scientific man. To solve the mysteries of the universe, as the French lady required a philosopher to explain his new system, "dans un mot," is beyond rational expectation. All that we have time and need to say of this little book upon great subjects relates to its spirit and to the view it takes of evolution. Its theology is wholly orthodox; its tone devotional, charitable, and hopeful; its confidence in religious truth, as taught both in Nature and revelation, complete; the illustrations often happy, but often too rhetorical; the science, as might be expected from this author, unimpeachable as regards matters of fact, discreet as to matters of opinion. The argument from design in the first lecture brings up the subject of the introduction of species. Of this, considered "as a question of history, there is no witness on the stand except geology." "The present condition of geological evidence is undoubtedly in favor of some degree of suddenness--is against infinite gradations. The evidence may be meagre . . . but whether meagre or not, it is all the evidence we have. . . . Now, the evidence of geology to-day is, that species seem to come in suddenly and in full perfection, remain substantially unchanged during the term of their existence, and pass away in full perfection. Other species take their place apparently by substitution, not by transmutation. But you will ask me, 'Do you, then, reject the doctrine of evolution? Do you accept the creation of species directly and without secondary agencies and processes?' I answer, No! Science knows nothing of phenomena which do not take place by secondary causes and processes. She does not deny such occurrence, for true Science is not dogmatic, and she knows full well that, tracing up the phenomena from cause to cause, we must somewhere reach the more direct agency of a First Cause. . . . It is evident that, however species were introduced, whether suddenly or gradually, it is the duty of Science ever to strive to understand the means and processes by which species originated. . . . Now, of the various conceivable secondary causes and processes, by some of which we must believe species originated, by far the most probable is certainly that of evolution from other species." (We might interpose the remark that the witness on the stand, if subjected to cross-examination by a biologist, might be made to give a good deal of testimony in favor of transmutation rather than substitution.) After referring to different ideas as to the cause or mode of evolution, he concludes that it can make no difference, so far as the argument of design in Nature is concerned, whether there be evolution or not, or whether, in the case of evolution, the change be paroxysmal or uniform. We may infer even that he accepts the idea that "physical and chemical forces are changed into vital force, and vice versa." Physicists incline more readily to this than physiologists; and if what is called vital force be a force in the physicists' sense, then it is almost certainly so. But the illustration on page 275 touches this point only seemingly. It really concerns only the storing and the using of physical force in a living organism. If, for want of a special expression, we continue to use the term vital force to designate that intangible something which directs and governs the accumulation and expenditure of physical force in organisms, then there is as yet no proof and little likelihood that this is correlate with physical force. "A few words upon the first chapter of Genesis and the Mosaic cosmogony, and I am done," says Prof. Le Conte, and so are we: "It might be expected by many that, after speaking of schemes of reconciliation, I should give mine also. My Christian friends, these schemes of reconciliation become daily more and more distasteful to me. I have used them in times past; but now the deliberate construction of such schemes seems to me almost like trifling with the words of Scripture and the teachings of Nature. They seem to me almost irreverent, and quite foreign to the true, humble, liberal spirit of Christianity; they are so evidently artificial, so evidently mere ingenious human devices. It seems to me that if we will only regard the two books in the philosophical spirit which I have endeavored to describe, and then simply wait and possess our souls in patience, the questions in dispute will soon adjust themselves as other similar questions have already done." VIII WHAT IS DARWINISM? [VIII-1] The Nation, May 28, 1874) The question which Dr. Hodge asks he promptly and decisively answers: "What is Darwinism? it is atheism." Leaving aside all subsidiary and incidental matters, let us consider--1. What the Darwinian doctrine is, and 2. How it is proved to be atheistic. Dr. Hodge's own statement of it cannot be very much bettered: "His [Darwin's] work on the 'Origin of Species' does not purport to be philosophical. In this aspect it is very different from the cognate works of Mr. Spencer. Darwin does not speculate on the origin of the universe, on the nature of matter or of force. He is simply a naturalist, a careful and laborious observer, skillful in his descriptions, and singularly candid in dealing with the difficulties in the way of his peculiar doctrine. He set before himself a single problem--namely, How are the fauna and flora of our earth to be accounted for? . . . To account for the existence of matter and life, Mr. Darwin admits a Creator. This is done explicitly and repeatedly. . . . He assumes the efficiency of physical causes, showing no disposition to resolve them into mind-force or into the efficiency of the First Cause. . . . He assumes, also, the existence of life in the form of one or more primordial germs. . . . How all living things on earth, including the endless variety of plants and all the diversity of animals, . . . have descended from the primordial animalcule, he thinks, may be accounted for by the operation of the following natural laws, viz.: First, the law of Heredity, or that by which like begets like--the offspring are like the parent. Second, the law of Variation; that is, while the offspring are in all essential characteristics like their immediate progenitor, they nevertheless vary more or less within narrow limits from their parent and from each other. Some of these variations are indifferent, some deteriorations, some improvements--that is, such as enable the plant or animal to exercise its functions to greater advantage. Third, the law of Over-Production. All plants and animals tend to increase in a geometrical ratio, and therefore tend to overrun enormously the means of support. If all the seeds of a plant, all the spawn of a fish, were to arrive at maturity, in a very short time the world could not contain them. Hence, of necessity, arises a struggle for life. Only a few of the myriads born can possibly live. Fourth, here comes in the law of Natural Selection, or the Survival of the Fittest; that is, if any individual of a given species of plant or animal happens to have a slight deviation from the normal type favorable to its success in the struggle for life, it will survive. This variation, by the law of heredity, will be transmitted to its offspring, and by them again to theirs. Soon these favored ones gain the ascendency, and the less favored perish, and the modification becomes established in the species. After a time, another and another of such favorable variations occur, with like results. Thus, very gradually, great changes of structure are introduced, and not only species, but genera, families, and orders, in the vegetable and animal world, are produced" (pp. 26-29). Now, the truth or the probability of Darwin's hypothesis is not here the question, but only its congruity or incongruity with theism. We need take only one exception to this abstract of it, but that is an important one for the present investigation. It is to the sentence which we have italicized in the earlier part of Dr. Hodge's own statement of what Darwinism is. With it begins our inquiry as to how he proves the doctrine to be atheistic. First, if we rightly apprehend it, a suggestion of atheism is infused into the premises in a negative form: Mr. Darwin shows no disposition to resolve the efficiency of physical causes into the efficiency of the First Cause. Next (on page 48) comes the positive charge that "Mr. Darwin, although himself a theist," maintains that "the contrivances manifested in the organs of plants and animals . . . are not due to the continued cooperation and control of the divine mind, nor to the original purpose of God in the constitution of the universe." As to the negative statement, it might suffice to recall Dr. Hodge's truthful remark that Darwin "is simply a naturalist," and that "his work on the origin of species does not purport to be philosophical." In physical and physiological treatises, the most religious men rarely think it necessary to postulate the First Cause, nor are they misjudged by the omission. But surely Mr. Darwin does show the disposition which our author denies him, not only by implication in many instances, but most explicitly where one would naturally look for it, namely--at the close of the volume in question: "To my mind, it accords better with what we know of the laws impressed on matter by the Creator," etc. If that does not refer the efficiency of physical causes to the First Cause, what form of words could do so? The positive charge appears to be equally gratuitous. In both Dr. Hodge must have overlooked the beginning as well as the end of the volume which he judges so hardly. Just as mathematicians and physicists, in their systems, are wont to postulate the fundamental and undeniable truths they are concerned with, or what they take for such and require to be taken for granted, so Mr. Darwin postulates, upon the first page of his notable work, and in the words of Whewell and Bishop Butler: 1. The establishment by divine power of general laws, according to which, rather than by insulated interpositions in each particular case, events are brought about in the material world; and 2. That by the word ':natural" is meant "stated, fixed, or settled," by this same power, "since what is natural as much requires and presupposes an intelligent agent to render it so--i.e., to effect it continually or at stated times--as what is supernatural or miraculous does to effect it for once.[VIII-2] So when Mr. Darwin makes such large and free use of "natural as antithetical to supernatural" causes, we are left in no doubt as to the ultimate source which he refers them to. Rather let us say there ought to be no doubt, unless there are other grounds for it to rest upon. Such ground there must be, or seem to be, to justify or excuse a veteran divine and scholar like Dr. Hodge in his deduction of pure atheism from a system produced by a confessed theist, and based, as we have seen, upon thoroughly orthodox fundamental conceptions. Even if we may not hope to reconcile the difference between the theologian and the naturalist, it may be well to ascertain where their real divergence begins, or ought to begin, and what it amounts to. Seemingly, it is in their proximate, not in their ultimate, principles, as Dr. Hodge insists when he declares that the whole drift of Darwinism is to prove that everything "may be accounted for by the blind operation of natural causes, without any intention, purpose, or cooperation of God." "Why don't he say," cries the theologian, "that the complicated organs of plants and animals are the product of the divine intelligence? If God made them, it makes no difference, so far as the question of design is concerned, how he made them, whether at once or by process of evolution." But, as we have seen, Mr. Darwin does say that, and he over and over implies it when he refers the production of species "to secondary causes," and likens their origination to the origination of individuals; species being series of individuals with greater difference. It is not for the theologian to object that the power which made individual men and other animals, and all the differences which the races of mankind exhibit, through secondary causes, could not have originated congeries of more or less greatly differing individuals through the same causes. Clearly, then, the difference between the theologian and the naturalist is not fundamental, and evolution may be as profoundly and as particularly theistic as it is increasingly probable. The taint of atheism which, in Dr. Hodge's view, leavens the whole lump, is not inherent in the original grain of Darwinism--in the principles posited--but has somehow been introduced in the subsequent treatment. Possibly, when found, it may be eliminated. Perhaps there is mutual misapprehension growing out of some ambiguity in the use of terms. "Without any intention, purpose, or cooperation of God."- These are sweeping and effectual words. How came they to be applied to natural selection by a divine who professes that God ordained whatsoever cometh to pass? In this wise: "The point to be proved is, that it is the distinctive doctrine of Mr. Darwin that species owe their origin--1. Not to the original intention of the divine mind; 2. Not to special acts of creation calling new forms into existence at certain epochs; 3. Not to the constant and everywhere operative efficiency of God guiding physical causes in the production of intended effects; but 4. To the gradual accumulation of unintended variations of structure and instinct securing some advantage to their subjects." Then Dr. Hodge adduces "Darwin's own testimony," to the purport that natural selection denotes the totality of natural causes and their interactions, physical and physiological, reproduction, variation, birth, struggle, extinction--in short, all that is going on in Nature; that the variations which in this interplay are picked out for survival are not intentionally guided; that "nothing can be more hopeless than the attempt to explain this similarity of pattern in members of the same class by utility or the doctrine of final causes" (which Dr. Hodge takes to be the denial of any such thing as final causes); and that the interactions and processes going on which constitute natural selection may suffice to account for the present diversity of animals and plants (primordial organisms being postulated and time enough given) with all their structures and adaptations--that is, to account for them scientifically, as science accounts for other things. A good deal may be made of this, but does it sustain the indictment? Moreover, the counts of the indictment may be demurred to. It seems to us that only one of the three points which Darwin is said to deny is really opposed to the fourth, which he is said to maintain, except as concerns the perhaps ambiguous word unintended. Otherwise, the origin of species through the gradual accumulation of variations--i.e., by the addition of a series of small differences--is surely not incongruous with their origin through "the original intention of the divine mind" or through "the constant and everywhere operative efficiency of God."- One or both of these Mr. Darwin (being, as Dr. Hodge says, a theist) must needs hold to in some form or other; wherefore he may be presumed to hold the fourth proposition in such wise as not really to contradict the first or the third. The proper antithesis is with the second proposition only, and the issue comes to this: Have the multitudinous forms of living creatures, past and present, been produced by as many special and independent acts of creation at very numerous epochs? Or have they originated under causes as natural as reproduction and birth, and no more so, by the variation and change of preceding into succeeding species? Those who accept the latter alternative are evolutionists. And Dr. Hodge fairly allows that their views, although clearly wrong, may be genuinely theistic. Surely they need not become the less so by the discovery or by the conjecture of natural operations through which this diversification and continued adaptation of species to conditions is brought about. Now, Mr. Darwin thinks--and by this he is distinguished. from most evolutionists--that he can assign actual natural causes, adequate to the production of the present out of the preceding state of the animal and vegetable world, and so on backward--thus uniting, not indeed the beginning but the far past with the present in one coherent system of Nature. But in assigning actual natural causes and processes, and applying them to the explanation of the whole case, Mr. Dar-win assumes the obligation of maintaining their general sufficiency--a task from which the numerous advocates and acceptors of evolution on the general concurrence of probabilities and its usefulness as a working hypothesis (with or without much conception of the manner how) are happily free. Having hit upon a modus operandi which all who understand it admit will explain something, and many that it will explain very much, it is to be expected that Mr. Darwin will make the most of it. Doubtless he is far from pretending to know all the causes and operations at work; he has already added some and restricted the range of others; he probably looks for additions to their number and new illustrations of their efficiency; but he is bound to expect them all to fall within the category of what he calls natural selection (a most expansible principle), or to be congruous with it--that is, that they shall be natural causes. Also--and this is the critical point--he is bound to maintain their sufficiency without intervention. Here, at length, we reach the essential difference between Darwin, as we understand him, and Dr. Hodge. The terms which Darwin sometimes uses, and doubtless some of the ideas they represent, are not such as we should adopt or like to defend; and we may say once for all--aside though it be from the present issue--that, in our opinion, the adequacy of the assigned causes to the explanation of the phenomena has not been made out. But we do not understand him to deny "purpose, intention, or the cooperation of God" in Nature. This would be as gratuitous as unphilosophical, not to say unscientific. When he speaks of this or that particular or phase in the course of events or the procession of organic forms as not intended, he seems to mean not specially and disjunctively intended and not brought about by intervention. Purpose in the whole, as we suppose, is not denied but implied. And when one considers how, under whatever view of the case, the designed and the contingent lie inextricably commingled in this world of ours, past man's disentanglement, and into what metaphysical dilemmas the attempt at unraveling them leads, we cannot greatly blame the naturalist for relegating such problems to the philosopher and the theologian. If charitable, these will place the most favorable construction upon attempts to extend and unify the operation of known secondary causes, this being the proper business of the naturalist and physicist; if wise, they will be careful not to predicate or suggest the absence of intention from what comes about by degrees through the continuous operation of physical causes, even in the organic world, lest, in their endeavor to retain a probable excess of supernaturalism in that realm of Nature, they cut away the grounds for recognizing it at all in inorganic Nature, and so fall into the same condemnation that some of them award to the Darwinian. Moreover, it is not certain that Mr. Darwin would very much better his case, Dr. Hodge being judge, if he did propound some theory of the nexus of divine causation and natural laws, or even if he explicitly adopted the one or the other of the views which he is charged with rejecting. Either way he might meet a procrustean fate; and, although a saving amount of theism might remain, he would not be sound or comfortable. For, if he predicates "the constant and everywhere operative efficiency of God," he may "lapse into the same doctrine" that the Duke of Argyll and Sir John Herschel "seem inclined to," the latter of whom is blamed for thinking "it but reasonable to regard the force of gravitation as the direct or indirect result of a consciousness or will existing somewhere," and the former for regarding "it unphilosophical 'to think or speak as if the forces of Nature were either independent of or even separate from the Creator's power' ": while if he falls back upon an "original intention of the divine mind," endowing matter with forces which he foresaw and intended should produce such results as these contrivances in Nature, he is told that this banishes God from the world, and is inconsistent with obvious facts. And that because of its implying that "He never interferes to guide the operation of physical causes. We italicize the word, for interference proves to be the keynote of Dr. Hodge's system. Interference with a divinely ordained physical Nature for the accomplishment of natural results! An unorthodox friend has just imparted to us, with much misgiving and solicitude lest he should be thought irreverent, his tentative hypothesis, which is, that even the Creator may be conceived to have improved with time and experience! Never before was this theory so plainly and barely put before us. We were obliged to say that, in principle and by implication, it was not wholly original. But in such matters, which are far too high for us, no one is justly to be held responsible for the conclusions which another may draw from his principles or assumptions. Dr. Hodge's particular view should be gathered from his own statement of it: "In the external world there is always and everywhere indisputable evidence of the activity of two kinds of force, the one physical, the other mental. The physical belongs to matter, and is due to the properties with which it has been endowed; the other is the everywhere present and ever-acting mind of God. To the latter are to be referred all the manifestations of design in Nature, and the ordering of events in Providence. This doctrine does not ignore the efficiency of second causes; it simply asserts that God overrules and controls them. Thus the Psalmist says: 'I am fearfully and wonderfully made. My substance was not hid from Thee when I was made in secret, and curiously wrought (or embroidered) in the lower parts of the earth. . . . God makes the grass to grow, and herbs for the children of men.'- He sends rain, frost, and snow. He controls the winds and the waves. He determines the casting of the lot, the flight of an arrow, and the falling of a sparrow." Far be it from us to object to this mode of conceiving divine causation, although, like the two other theistic conceptions referred to, it has its difficulties, and perhaps the difficulties of both. But, if we understand it, it draws an unusually hard and fast line between causation in organic and inorganic Nature, seems to look for no manifestation of design in the latter except as "God overrules and controls" second causes, and, finally, refers to this overruling and controlling (rather than to a normal action through endowment) all embryonic development, the growth of vegetables, and the like. He even adds, without break or distinction, the sending of rain, frost, and snow, the flight of an arrow, and the falling of a sparrow. Somehow we must have misconceived the bearing of the statement; but so it stands as one of "the three ways," and the right way, of "accounting for contrivances in Nature; the other two being--1. Their reference to the blind operation of natural causes; and, 2. That they were foreseen and purposed by God, who endowed matter with forces which he foresaw and intended should produce such results, but never interferes to guide their operation. In animadverting upon this latter view, Dr. Hodge brings forward an argument against evolution, with the examination of which our remarks must close: "Paley, indeed, says that if the construction of a watch be an undeniable evidence of design, it would be a still more wonderful manifestation of skill if a watch could be made to produce other watches, and, it may be added, not only other watches, but all kinds of timepieces, in endless variety. So it has been asked, If a man can make a telescope, why cannot God make a telescope which produces others like itself? This is simply asking whether matter can be made to do the work of mind. The idea involves a contradiction. For a telescope to make a telescope supposes it to select copper and zinc in due proportions, and fuse them into brass; to fashion that brass into inter-entering tubes; to collect and combine the requisite materials for the different kinds of glass needed; to melt them, grind, fashion, and polish them, adjust their densities, focal distances, etc., etc. A man who can believe that brass can do all this might as well believe in God" (pp. 45, 46). If Dr. Hodge's meaning is, that matter unconstructed cannot do the work of mind, he misses the point altogether; for original construction by an intelligent mind is given in the premises. If he means that the machine cannot originate the power that operates it, this is conceded by all except believers in perpetual motion, and it equally misses the point; for the operating power is given in the case of the watch, and implied in that of the reproductive telescope. But if he means that matter cannot be made to do the work of mind in constructions, machines, or organisms, he is surely wrong. "Sovitur ambulando," vel scribendo; he confuted his argument in the act of writing the sentence. That is just what machines and organisms are for; and a consistent Christian theist should maintain that is what all matter is for. Finally, if, as we freely suppose, he means none of these, he must mean (unless we are much mistaken) that organisms originated by the Almighty Creator could not be endowed with the power of producing similar organisms, or slightly dissimilar organisms, without successive interventions. Then he begs the very question in dispute, and that, too, in the face of the primal command, "Be fruitful and multiply," and its consequences in every natural birth. If the actual facts could be ignored, how nicely the parallel would run! "The idea involves a contradiction." For an animal to make an animal, or a plant to make a plant, supposes it to select carbon, hydrogen, oxygen, and nitrogen, to combine these into cellulose and protoplasm, to join with these some phosphorus, lime, etc., to build them into structures and usefully-adjusted organs. A man who can believe that plants and animals can do this (not, indeed, in the crude way suggested, but in the appointed way) "might as well believe in God." Yes, verily, and so he probably will, in spite of all that atheistical philosophers have to offer, if not harassed and confused by such arguments and statements as these. There is a long line of gradually-increasing divergence from the ultra-orthodox view of Dr. Hodge through those of such men as Sir William Thomson, Herschel, Argyll, Owen, Mivart, Wallace, and Darwin, down to those of Strauss, Vogt, and Buchner. To strike the line with telling power and good effect, it is necessary to aim at the right place. Excellent as the present volume is in motive and clearly as it shows that Darwinism may bear an atheistic as well as a theistic interpretation, we fear that it will not contribute much to the reconcilement of science and religion. The length of the analysis of the first book on our list precludes the notices which we intended to take of the three others. They are all the production of men who are both scientific and religious, one of them a celebrated divine and writer unusually versed in natural history. They all look upon theories of evolution either as in the way of being established or as not unlikely to prevail, and they confidently expect to lose thereby no solid ground for theism or religion. Mr. St. Clair, a new writer, in his "Darwinism and Design; or, Creation by Evolution," takes his ground in the following succinct statement of his preface: "It is being assumed by our scientific guides that the design-argument has been driven out of the field by the doctrine of evolution. It seems to be thought by our theological teachers that the best defense of the faith is to deny evolution in toto, and denounce it as anti-Biblical. My volume endeavors to show that, if evolution be true, all is not lost; but, on the contrary, something is gained: the design-argument remains unshaken, and the wisdom and beneficence of God receive new illustration." Of his closing remark, that, so far as he knows, the subject has never before been handled in the same way for the same purpose, we will only say that the handling strikes us as mainly sensible rather than as substantially novel. He traverses the whole ground of evolution, from that of the solar system to "the origin of moral species." He is clearly a theistic Darwinian without misgiving, and the arguments for that hypothesis and for its religious aspects obtain from him their most favorable presentation, while he combats the dysteleology of Hackel, Buchner, etc., not, however, with any remarkable strength. Dr. Winchell, chancellor of the new university at Syracuse, in his volume just issued upon the "Doctrine of Evolution," adopts it in the abstract as "clearly as the law of universal intelligence under which complex results are brought into existence" (whatever that may mean), accepts it practically for the inorganic world as a geologist should, hesitates as to the organic world, and sums up the arguments for the origin of species by diversification unfavorably for the Darwinians, regarding it mainly from the geological side. As some of our zoologists and palaeontologists may have somewhat to say upon this matter, we leave it for their consideration. We are tempted to develop a point which Dr. Winchell incidentally refers to--viz., how very modern the idea of the independent creation and fixity of species is, and how well the old divines got on without it. Dr. Winchell reminds us that St. Augustine and St. Thomas Aquinas were model evolutionists; and, where authority is deferred to, this should count for something. Mr. Kingsley's eloquent and suggestive "Westminster Sermons," in which he touches here and there upon many of the topics which evolution brings up, has incorporated into the preface a paper which he read in 187i to a meeting of London clergy at Sion College, upon certain problems of natural theology as affected by modern theories in science. We may hereafter have occasion to refer to this volume. Meanwhile, perhaps we may usefully conclude this article with two or three short extracts from it: "The God who satisfies our conscience ought more or less to satisfy our reason also. To teach that was Butler's mission; and he fulfilled it well. But it is a mission which has to be refulfilled again and again, as human thought changes, and human science develops, For if, in any age or country, the God who seems to be revealed by Nature seems also different from the God who is revealed by the then-popular religion, then that God and the religion which tells of that God will gradually cease to be believed in. "For the demands of reason--as none knew better than good Bishop Butler--must be and ought to be satisfied. And, therefore, when a popular war arises between the reason of any generation and its theology, then it behooves the ministers of religion to inquire, with all humility and godly fear, on whose side lies the fault; whether the theology which they expound is all that it should be, or whether the reason of those who impugn it is all that it should be." Pronouncing it to be the duty of the naturalist to find out the how of things, and of the natural theologian to find out the why, Mr. Kingsley continues: "But if it be said, 'After all, there is no why; the doctrine of evolution, by doing away with the theory of creation, does away with that of final causes,' let us answer boldly, 'Not in the least.' We might accept all that Mr. Darwin, all that Prof. Huxley, all that other most able men have so learnedly and acutely written on physical science, and yet preserve our natural theology on the same basis as that on which Butler and Paley left it. That we should have to develop it I do not deny. "Let us rather look with calmness, and even with hope and good-will, on these new theories; they surely mark a tendency toward a more, not a less, Scriptural view of Nature. "Of old it was said by Him, without whom nothing is made, 'My Father worketh hitherto, and I work.' Shall we quarrel with Science if she should show how these words are true? What, in one word, should we have to say but this: 'We know of old that God was so wise that he could make all things; but, behold, he is so much wiser than even that, that he can make all things make themselves?' " CHARLES DARWIN: A SKETCH (Nature, June 4, 1874, accompanying a portrait) Two British naturalists, Robert Brown and Charles Darwin, have, more than any others, impressed their influence upon science in this nineteenth century. Unlike as these men and their works were and are, we may most readily subserve the present purpose in what we are called upon to say of the latter by briefly comparing and contrasting the two. Robert Brown died sixteen years ago, full of years and scientific honors, and he seems to have finished, several years earlier, all the scientific work that he had undertaken. To the other, Charles Darwin, a fair number of productive years may yet remain, and are earnestly hoped for. Both enjoyed the great advantage of being all their lives long free from exacting professional duties or cares, and so were able in the main to apply themselves to research without distraction and according to their bent. Both, at the beginning of their career, were attached to expeditions of exploration in the southern hemisphere, where they amassed rich stores of observation and materials, and probably struck out, while in the field, some of the best ideas which they subsequently developed. They worked in different fields and upon different methods; only in a single instance, so far as we know, have they handled the same topic; and in this the more penetrating insight of the younger naturalist into an interesting general problem may be appealed to in justification of a comparison which some will deem presumptuous. Be this as it may, there will probably be little dissent from the opinion that the characteristic trait common to the two is an unrivaled scientific sagacity. In this these two naturalists seem to us, each in his way, preeminent. There is a characteristic likeness, too--underlying much difference--in their admirable manner of dealing with facts closely, and at first hand, without the interposition of the formal laws, vague ideal conceptions, or "glittering generalities" which some philosophical naturalists make large use of. A likeness may also be discerned in the way in which the work or contributions of predecessors and contemporaries are referred to. The brief historical summaries prefixed to many of Mr. Brown's papers are models of judicial conscientiousness. And Mr. Darwin's evident delight at discovering that some one else has "said his good things before him," or has been on the verge of uttering them, seemingly equals that of making the discovery himself. It reminds one of Goethe's insisting that his views in morphology must have been held before him and must be somewhere on record, so obvious did they appear to him. Considering the quiet and retired lives led by both these men, and the prominent place they are likely to occupy in the history of science, the contrast between them as to contemporary and popular fame is very remarkable. While Mr. Brown was looked up to with the greatest reverence by all the learned botanists, he was scarcely heard of by any one else; and out of botany he was unknown to science except as the discoverer of the Brownian motion of minute particles, which discovery was promulgated in a privately-printed pamphlet that few have ever seen. Although Mr. Darwin had been for twenty years well and widely known for his "Naturalist's Journal," his works on "Coral Islands," on "Volcanic Islands, and especially for his researches on the Barnacles, it was not till about fifteen years ago that his name became popularly famous. Ever since no scientific name has been so widely spoken. Many others have had hypotheses or systems named after them, but no one else that we know of a department of bibliography. The nature of his latest researches accounts for most of the difference, but not for all, The Origin of Species is a fascinating topic, having interests and connections with every branch of science, natural and moral. The investigation of recondite affinities is very dry and special; its questions, processes, and results alike--although in part generally presentable in the shape of morphology--are mainly, like the higher mathematics, unintelligible except to those who make them a subject of serious study. They are especially so when presented in Mr. Brown's manner. Perhaps no naturalist ever recorded the results of his investigations in fewer words and with greater precision than Robert Brown: certainly no one ever took more pains to state nothing beyond the precise point in question. Indeed, we have sometimes fancied that he preferred to enwrap rather than to explain his meaning; to put it into such a form that, unless you follow Solomon's injunction and dig for the wisdom as for hid treasure, you may hardly apprehend it until you have found it all out for yourself, when you will have the satisfaction of perceiving that Mr. Brown not only knew all about it, but had put it upon record. Very different from this is the way in which Mr. Darwin takes his readers into his confidence, freely displays to them the sources of his information, and the working of his mind, and even shares with them all his doubts and misgivings, while in a clear exposition he sets forth the reasons which have guided him to his conclusions. These you may hesitate or decline to adopt, but you feel sure that they have been presented with perfect fairness; and if you think of arguments against them you may be confident that they have all been duly considered before. The sagacity which characterizes these two naturalists is seen in their success in finding decisive instances, and their sure insight into the meaning of things. As an instance of the latter on Mr. Darwin's part, and a justification of our venture to compare him with the facile princeps botanicorum, we will, in conclusion, allude to the single instance in which they took the same subject in hand. In his papers on the organs and modes of fecundation in Orchideae and Asclepiadeae, Mr. Brown refers more than once to C.K. Sprengel's almost forgotten work, shows how the structure of the flowers in these orders largely requires the agency of insects for their fecundation, and is aware that "in Asclepiadeae . . . the insect so readily passes from one corolla to another that it not unfrequently visits every flower of the umbel." He must also have contemplated the transport of pollen from plant to plant by wind and insects; and we know from another source that he looked upon Sprengel's ideas as far from fantastic. Yet, instead of taking the single forward step which now seems so obvious, he even hazarded the conjecture that the insect-forms of some orchideous flowers are intended to deter rather than to attract insects. And so the explanation of all these and other extraordinary structures, as well as of the arrangement of blossoms in general, and even the very meaning and need of sexual propagation, were left to be supplied by Mr. Darwin. The aphorism "Nature abhors a vacuum" is a characteristic specimen of the science of the middle ages. The aphorism "Nature abhors close fertilization," and the demonstration of the principle, belong to our age, and to Mr. Darwin. To have originated this, and also the principle of natural selection--the truthfulness and importance of which are evident the moment it is apprehended--and to have applied these principles to the system of Nature in such a manner as to make, within a dozen years, a deeper impression upon natural history than has been made since Linnaeus, is ample title for one man's fame. There is no need of our giving any account or of estimating the importance of such works as the "Origin of Species by means of Natural Selection," the "Variation of Animals and Plants under Domestication," the "Descent of Man, and Selection in Relation to Sex," and the "Expression of the Emotions in Men and Animals"--a series to which we may hope other volumes may in due time be added. We would rather, if space permitted, attempt an analysis of the less known, but not less masterly, subsidiary essays, upon the various arrangements for insuring cross-fertilization in flowers, for the climbing of plants, and the like. These, as we have heard, may before long be reprinted in a volume, and supplemented by some long-pending but still unfinished investigations upon the action of Dionaea and Drosera--a capital subject for Mr. Darwin's handling. A propos to these papers, which furnish excellent illustrations of it, let us recognize Darwin's great service to natural science in bringing back to it Teleology; so that, instead of Morphology versus Teleology, we shall have Morphology wedded to Teleology. To many, no doubt, evolutionary Teleology comes in such a questionable shape as to seem shorn of all its goodness; but they will think better of it in time, when their ideas become adjusted, and they see what an impetus the new doctrines have given to investigation. They are much mistaken who suppose that Darwinism is only of speculative importance, and perhaps transient interest. In its working applications it has proved to be a new power, eminently practical and fruitful. And here, again, we are bound to note a striking contrast to Mr. Brown, greatly as we revere his memory. He did far less work than was justly to be expected from him. Mr. Darwin not only points out the road, but labors upon it indefatigably and unceasingly. A most commendable noblesse oblige assures us that he will go on while strength (would we could add health) remains. The vast amount of such work he has already accomplished might overtax the powers of the strongest. That it could have been done at all under constant infirm health is most wonderful. X INSECTIVOROUS PLANTS (The Nation, April 2 and 9, 1874) That animals should feed upon plants is natural and normal, and the reverse seems impossible. But the adage, "Natura non agit saltatim," has its application even here. It is the naturalist, rather than Nature, that draws hard and fast lines everywhere, and marks out abrupt boundaries where she shades off with gradations. However opposite the parts which animals and vegetables play in the economy of the world as the two opposed kingdoms of organic Nature, it is becoming more and more obvious that they are not only two contiguous kingdoms, but are parts of one whole--antithetical and complementary to each other, indeed; but such "thin partitions do the bounds divide" that no definitions yet framed hold good without exception. This is a world of transition in more senses than is commonly thought; and one of the lessons which the philosophical naturalist learns, or has to learn, is, that differences the most wide and real in the main, and the most essential, may nevertheless be here and there connected or bridged over by gradations. There is a limbo filled with organisms which never rise high enough in the scale to be manifestly either animal or plant, unless it may be said of some of them that they are each in turn and neither long. There are undoubted animals which produce the essential material of vegetable fabric, or build up a part of their structure of it, or elaborate the characteristic leaf-green which, under solar light, assimilates inorganic into organic matter, the most distinguishing function of vegetation. On the other hand, there are plants--microscopic, indeed, but unquestionable--which move spontaneously and freely around and among animals that are fixed and rooted. And, to come without further parley to the matter in hand, while the majority of animals feed directly upon plants, "for 'tis their nature to," there are plants which turn the tables and feed upon them. Some, being parasitic upon living animals, feed insidiously and furtively; these, although really cases in point, are not so extraordinary, and, as they belong to the lower orders, they are not much regarded, except for the harm they do. There are others, and those of the highest orders, which lure or entrap animals in ways which may well excite our special wonder--all the more so since we are now led to conclude that they not only capture but consume their prey. As respects the two or three most notable instances, the conclusions which have been reached are among the very recent acquisitions of physiological science. Curiously enough, however, now that they are made out, it appears that they were in good part long ago attained, recorded, and mainly forgotten. The earlier observations and surmises shared the common fate of discoveries made before the time, or by those who were not sagacious enough to bring out their full meaning or importance. Vegetable morphology, dimly apprehended by Linnaeus, initiated by Casper Frederick Wolff, and again, independently in successive generations, by Goethe and by De Candolle, offers a parallel instance. The botanists of Goethe's day could not see any sense, advantage, or practical application, to be made of the proposition that the parts of a blossom answer to leaves; and so the study of homologies had long to wait. Until lately it appeared to be of no consequence whatever (except, perhaps, to the insects) whether Drosera and Sarracenia caught flies or not; and even Dionaea excited only unreflecting wonder as a vegetable anomaly. As if there were real anomalies in Nature, and some one plant possessed extraordinary powers denied to all others, and (as was supposed) of no importance to itself! That most expert of fly-catchers, Dionaea, of which so much has been written and so little known until lately, came very near revealing its secret to Solander and Ellis a hundred years ago, and doubtless to John Bartram, our botanical pioneer, its C probable discoverer, who sent it to Europe. Ellis, in his published letter to Linnaeus, with which the history begins, described the structure and action of the living trap correctly; noticed that the irritability which called forth the quick movement closing the trap, entirely resided in the few small bristles of its upper face; that this whole surface was studded C with glands, which probably secreted a liquid; and that the trap did not open again when an insect was captured, even upon the death of the captive, although it opened very soon when nothing was caught, or when the irritation was caused by a bit of straw, or any such substance. It was Linnaeus who originated the contrary and erroneous statement, which has long prevailed in the books, that the trap reopened when the fatigued captive became quiet, and let it go; as if the plant caught flies in mere play and pastime! Linnaeus also omitted all allusion to a secreted liquid--which was justifiable, as. Ellis does not state that he had actually seen any; and, if he did see it, quite mistook its use, supposing it to be, like the nectar of flowers, a lure for insects, a bait for the trap. Whereas, in fact, the lure, if there be any, must be an odor (although nothing is perceptible to the human olfactories); for the liquid secreted by the glands never appears until the trap has closed upon some insect, and held it at least for some hours a prisoner. Within twenty-four or forty-eight hours this glairy liquid is abundant, bathing and macerating the body of the perished insect. Its analogue is not the nectar of flowers, but the saliva or the gastric juice! The observations which compel such an inference are re-cent, and the substance of them may be briefly stated. The late Rev. Dr. M. A. Curtis (by whose death, two years ago, we lost one of our best botanists, and the master in his especial line, mycology), forty years and more ago resided at Wilmington, North Carolina, in the midst of the only district to which the Dionaea is native; and he published, in 1834, in the first volume of the "Journal of the Boston Society of Natural History," by far the best account of this singular plant which had then appeared. He remarks that "the little prisoner is not crushed and suddenly destroyed, as is sometimes supposed," for he had often liberated "captive flies and spiders, which sped away as fast as fear or joy could hasten them." But he neglected to state, although he must have noticed the fact, that the two sides of the trap, at first concave to the contained insect, at length flatten and close down firmly upon the prey, exerting no inconsiderable pressure, and insuring the death of any soft-bodied insect, if it had not already succumbed to the confinement and salivation. This last Dr. Curtis noticed, and first discerned its import, although he hesitated to pronounce upon its universality. That the captured insects were in some way "made subservient to the nourishment of the plant" had been conjectured from the first. Dr. Curtis "at times (and he might have always at the proper time) found them enveloped in a fluid of mucilaginous consistence, which seems to act as a solvent, the insects being more or less consumed in it." This was verified and the digestive character of the liquid well-nigh demonstrated six or seven years ago by Mr. Canby, of Wilmington, Delaware, who, upon a visit to the sister-town of North Carolina, and afterward at his home, followed up Dr. Curtis's suggestions with some capital observations and experiments. These were published at Philadelphia in the tenth volume of Meehan's Gardeners' Monthly, August, i868; but they do not appear to have attracted the attention which they merited. The points which Mr. Canby made out are, that this fluid is always poured out around the captured insect in due time, "if the leaf is in good condition and the prey suitable;" that it comes from the leaf itself, and not from the decomposing insect (for, when the trap caught a plum-curculio, the fluid was poured out while he was still alive, though very weak, and endeavoring, ineffectively, to eat his way out); that bits of raw beef, although sometimes rejected after a while, were generally acted upon in the same manner--i.e., closed down upon tightly, salvered with the liquid, dissolved mainly, and absorbed; so that, in fine, the fluid may well be said to be analogous to the gastric juice of animals, dissolving the prey and rendering it fit for absorption by the leaf. Many leaves remain inactive or slowly die away after one meal; others reopen for a second and perhaps even a third capture, and are at least capable of digesting a second meal. Before Mr. Canby's experiments had been made, we were aware that a similar series had been made in England by Mr. Darwin, with the same results, and with a small but highly-curious additional one--namely, that the fluid secreted in the trap of Dionaea, like the gastric juice, has an acid reaction. Having begun to mention unpublished results (too long allowed to remain so), it may be well, under the circumstances, to refer to a still more remarkable experiment by the same most sagacious investigator. By a prick with a sharp lancet at a certain point, he has been able to paralyze one-half of the leaf-trap, so that it remained motionless under the stimulus to which the other half responded. Such high and sensitive organization entails corresponding ailments. Mr. Canby tells us that he gave to one of his Dionaea-subjects a fatal dyspepsia by feeding it with cheese; and under Mr. Darwin's hands another suffers from paraplegia. Finally, Dr. Burdon-Sanderson's experiments, detailed at the last meeting of the British Association for the Advancement of Science, show that the same electrical currents are developed upon the closing of the Dionaea-trap as in the contraction of a muscle. If the Venus's Fly-trap stood alone, it would be doubly marvelous--first, on account of its carnivorous propensities, and then as constituting a real anomaly in organic Nature, to which nothing leads up. Before acquiescing in such a conclusion, the modern naturalist would scrutinize its relatives. Now, the nearest relatives of our vegetable wonder are the sundews. While Dionaea is as local in habitation as it is singular in structure and habits, the Droseras or sundews are widely diffused over the world and numerous in species. The two whose captivating habits have attracted attention abound in bogs all around the northern hemisphere. That flies are caught by them is a matter of common observation; but this was thought to be purely accidental. They spread out from the root a circle of small leaves, the upper face of which especially is beset and the margin fringed with stout bristles (or what seem to be such, although the structure is more complex), tipped by a secreting gland, which produces, while in vigorous state, a globule of clear liquid like a drop of dew-- whence the name, both Greek and English. One expects these seeming dew-drops to be dissipated by the morning sun; but they remain unaffected. A touch shows that the glistening drops are glutinous and extremely tenacious, as flies learn to their cost on alighting, perhaps to sip the tempting liquid, which acts first as a decoy and then like birdlime. A small fly is held so fast, and in its struggles comes in contact with so many of these glutinous globules, that it seldom escapes. The result is much the same to the insect, whether captured in the trap of Dionaea or stuck fast to the limed bristles of Drosera. As there are various plants upon whose glandular hairs or glutinous surfaces small insects are habitually caught and perish, it might be pure coincidence that the most effectual arrangement of the kind happens to occur in the nearest relatives of Dionaea. Roth, a keen German botanist of the eighteenth century, was the first to detect, or at least to record, some evidence of intention in Drosera, and to compare its action with that of Dionaea, which, through Ellis's account, had shortly before been made known in Europe. He noticed the telling fact that not only the bristles which the unfortunate insect had come in contact with, but also the surrounding rows, before widely spreading, curved inward one by one, although they had not been touched, so as within a few hours to press their glutinous tips likewise against the body of the captive insect--thus doubling or quadrupling the bonds of the victim and (as we may now suspect) the surfaces through which some part of the animal substance may be imbibed. For Roth surmised that both these plants were, in their way, predaceous. He even observed that the disk of the Drosera-leaf itself often became concave and enveloped the prey. These facts, although mentioned now and then in some succeeding works, were generally forgotten, except that of the adhesion of small insects to the leaves of sundews, which must have been observed in every generation. Up to and even within a few years past, if any reference was made to these asserted movements (as by such eminent physiologists as Meyen and Treviranus) it was to discredit them. Not because they are difficult to verify, but because, being naturally thought improbable, it was easier to deny or ignore them. So completely had the knowledge of almost a century ago died out in later years that, when the subject was taken up anew in our days by Mr. Darwin, he had, as we remember, to advertise for it, by sending a "note and query" to the magazines, asking where any account of the fly-catching of the leaves of sundew was recorded. When Mr. Darwin takes a matter of this sort in hand, he is not likely to leave it where he found it. He not only confirmed all Roth's observations as to the incurving of the bristles toward and upon an insect entangled on any part of the disk of the leaf, but also found that they responded similarly to a bit of muscle or other animal substance, while to any particles of inorganic matter they were nearly indifferent. To minute fragments of carbonate of ammonia, however, they were more responsive. As these remarkable results, attained (as we are able to attest) half a dozen years ago, remained unpublished (being portions of an investigation not yet completed), it would have been hardly proper to mention them, were it not that independent observers were beginning to bring out the same or similar facts. Mrs. Treat, of New Jersey, noticed the habitual infolding of the leaf in the longer-leaved species of sundew (American Journal of Science for November, 1871), as was then thought for the first time--Roth's and Withering's observations not having been looked up. In recording this, the next year, in a very little book, entitled "How Plants Behave," the opportunity was taken to mention, in the briefest way, the capital discovery of Mr. Darwin that the leaves of Drosera act differently when different objects are placed upon them, the bristles closing upon a particle of raw meat as upon a living insect, while to a particle of chalk or wood they are nearly inactive. The same facts were independently brought out by Mr. A. W. Bennett at the last year's meeting of the British Association for the Advancement of Science, and have been mentioned in the journals. If to these statements, which we may certify, were added some far more extraordinary ones, communicated to the French Academy of Science in May last by M. Zeigler, a stranger story of discrimination on the part of sundew-bristles would be told. But it is safer to wait for the report of the committee to which these marvels were referred, and conclude this sufficiently "strange eventful history" with some details of experiments made last summer by Mrs. Treat, of New Jersey, and published in the December number of the American Naturalist. It is well to note that Mrs. Treat selects for publication the observations of one particular day in July, when the sundew-leaves were unusually active; for their moods vary with the weather, and also in other unaccountable ways, although in general the sultrier days are the most appetizing: "At fifteen minutes past ten of the same day I placed bits of raw beef on some of the most vigorous leaves of Drosera longifolia. Ten minutes past twelve, two of the leaves had folded around the beef, hiding it from sight. Half-past eleven of the same day, I placed living flies on the leaves of D. longifolia. At 12 and 48 minutes one of the leaves had folded entirely around its victim, the other leaves had partially folded, and the flies had ceased to struggle. By 2 and 30 minutes four leaves had each folded around a fly. . . . I tried mineral substances--bits of dry chalk, magnesia, and pebbles. In twenty-four hours, neither the leaves nor their bristles had made any move like clasping these articles. I wet a piece of chalk in water, and in less than an hour the bristles were curving about it, but soon unfolded again, leaving the chalk free on the blade of the leaf. Parallel experiments made on D. rotundifolia, with bits of beef and of chalk, gave the same results as to the action of the bristles; while with a piece of raw apple, after eleven hours, "part of the bristles were clasping it, but not so closely as the beef," and in twenty-four hours "nearly all the bristles were curved toward it, but not many of the glands were touching it." To make such observations is as easy as it is interesting. Throughout the summer one has only to transfer plants of Drosera from the bogs into pots or pans filled with wet moss--if need be, allowing them to become established in the somewhat changed conditions, or even to put out fresh leaves--and to watch their action or expedite it by placing small flies upon the disk of the leaves. The more common round-leaved sundew acts as well as the other by its bristles, and the leaf itself is sometimes almost equally prehensile, although in a different way, infolding the whole border instead of the summit only. Very curious, and even somewhat painful, is the sight when a fly, alighting upon the central dew-tipped bristles, is held as fast as by a spider's web; while the efforts to escape not only entangle the insect more hopelessly as they exhaust its strength, but call into action the surrounding bristles, which, one by one, add to the number of the bonds, each by itself apparently feeble, but in their combination so effectual that the fly may be likened to the sleeping Gulliver made fast in the tiny but multitudinous toils of the Liliputians. Anybody who can believe that such an apparatus was not intended to capture flies might say the same of a spider's web. Is the intention here to be thought any the less real because there are other species of Drosera which are not so perfectly adapted for fly-catching, owing to the form of their leaves and the partial or total want of cooperation of their scattered bristles? One such species, D. filiformis, the thread-leaved sundew, is not uncommon in this country, both north and south of the district that Dionaea locally inhabits. Its leaves are long and thread-shaped, beset throughout with glutinous gland-tipped bristles, but wholly destitute of a blade. Flies, even large ones, and even moths and butterflies, as Mrs. Treat and Mr. Canby affirm (in the American Naturalist), get stuck fast to these bristles, whence they seldom escape. Accidental as such captures are, even these thread-shaped leaves respond more or less to the contact, somewhat in the manner of their brethren. In Mr. Canby's recent and simple experiment, made at Mr. Darwin's suggestion, when a small fly alights upon a leaf a little below its slender apex, or when a bit of crushed fly is there affixed, within a few hours the tip of the leaf bends at the point of contact, and curls over or around the body in question; and Mrs. Treat even found that when living flies were pinned at half an inch in distance from the leaves, these in forty minutes had bent their tips perceptibly toward the flies, and in less than two hours reached them! If this be confirmed--and such a statement needs ample confirmation--then it may be suspected that these slender leaves not only incurve after prolonged contact, just as do the leaf-stalks of many climbers, but also make free and independent circular sweeps, in the manner of twining stems and of many tendrils. Correlated movements like these indicate purpose. When performed by climbing plants, the object and the advantage are obvious. That the apparatus and the actions of Dionaea and Drosera are purposeless and without advantage to the plants themselves, many have been believed in former days, when it was likewise conceived that abortive and functionless organs were specially created "for the sake of symmetry" and to display a plan; but this is not according to the genius of modern science. In the cases of insecticide next to be considered, such evidence of intent is wanting, but other and circumstantial evidence may be had, sufficient to warrant convictions. Sarracenias have hollow leaves in the form of pitchers or trumpet-shaped tubes, containing water, in which flies and other insects are habitually drowned. They are all natives of the eastern side of North America, growing in bogs or low ground, so that they cannot be supposed to need the water as such. Indeed, they secrete a part if not all of it. The commonest species, and the only one at the North, which ranges from Newfoundland to Florida, has a broad-mouthed pitcher with an upright lid, into which rain must needs fall more or less. The yellow Sarracenia, with long tubular leaves, called "trumpets in the Southern States, has an arching or partly upright lid, raised well above the orifice, so that some water may rain in; but a portion is certainly secreted there, and may be seen bedewing the sides and collected at the bottom before the mouth opens. In other species, the orifice is so completely overarched as essentially to prevent the access of water from without. In these tubes, mainly in the water, flies and other insects accumulate, perish, and decompose. Flies thrown into the open-mouthed tube of the yellow Sarracenia, even when free from water, are unable to get out--one hardly sees why, except that they cannot fly directly upward; and microscopic chevaux-de-frise of fine, sharp-pointed bristles which line most of the interior, pointing strictly downward, may be a more effectual obstacle to crawling up the sides than one would think possible. On the inside of the lid or hood of the purple Northern species, the bristles are much stronger; but an insect might escape by the front without encountering these. In this species, the pitchers, however, are so well supplied with water that the insects which somehow are most abundantly attracted thither are effectually drowned, and the contents all summer long are in the condition of a rich liquid manure. That the tubes or pitchers of the Southern species are equally attractive and fatal to flies is well known. Indeed, they are said to be taken into houses and used as fly-traps. There is no perceptible odor to draw insects, except what arises from the decomposition of macerated victims; nor is any kind of lure to be detected at the mouth of the pitcher of the common purple-flowered species. Some incredulity was therefore natural when it was stated by a Carolinian correspondent (Mr. B.F. Grady) that in the long-leaved, yellow-flowered species the lid just above the mouth of the tubular pitcher habitually secretes drops of a sweet and viscid liquid, which attracts flies and apparently intoxicates them, since those that sip it soon become unsteady in gait and mostly fall irretrievably into the well beneath. But upon cultivating plants of this species, obtained for the purpose, the existence of this lure was abundantly verified; and, although we cannot vouch for its inebriating quality, we can no longer regard it as unlikely. No sooner was it thus ascertained that at least one species of Sarracenia allures flies to their ruin than it began to appear that--just as in the case of Drosera--most of this was a mere revival of obsolete knowledge. The "insect-destroying process" was known and well described sixty years ago, the part played by the sweet exudation indicated, and even the intoxication perhaps hinted at, although evidently little thought of in those ante-temperance days. Dr. James Macbride, of South Carolina--the early associate of Elliott in his "Botany of South Carolina and Georgia," and to whose death, at the age of thirty-three, cutting short a life of remarkable promise, the latter touchingly alludes in the preface to his second volume--sent to Sir James Edward Smith an account of his observations upon this subject, made in 1810 and the following years. This was read to the Linnaean Society in 1815, and published in the twelfth volume of its "Transactions." From this forgotten paper (to which attention has lately been recalled) we cull the following extracts, premising that the observations mostly relate to a third species, Sarracenia adunca, alias variolaris, which is said to be the most efficient fly-catcher of the kind: "If, in the months of May, June, or July, when the leaves of those plants perform their extraordinary functions in the greatest perfection, some of them be removed to a house and fixed in an erect position, it will soon be perceived that flies are attracted by them. These insects immediately approach the fauces of the leaves, and, leaning over their edges, appear to sip with eagerness something from their internal surfaces. In this position they linger; but at length, allured as it would seem by the pleasure of taste, they enter the tubes. The fly which has thus changed its situation will be seen to stand unsteadily; it totters for a few seconds, slips, and falls to the bottom of the tube, where it is either drowned or attempts in vain to ascend against the points of the hairs. The fly seldom takes wing in its fall and escapes. . . . in a house much infested with flies, this entrapment goes on so rapidly that a tube is filled in a few hours, and it becomes necessary to add water, the natural quantity being insufficient to drown the imprisoned insects. The leaves of S. adunca and rubra might well be employed as fly-catchers; indeed, I am credibly informed they are in some neighborhoods. The leaves of the S. flava [the species to which our foregoing remarks mainly relate], although they are very capacious, and often grow to the height of three feet or more, are never found to contain so many insects as those of the species above mentioned. "The cause which attracts flies is evidently a sweet, viscid substance resembling honey, secreted by or exuding from the internal surface of the tube . . . From the margin, where it commences, it does not extend lower than one-fourth of an inch. "The falling of the insect as soon as it enters the tube is wholly attributable to the downward or inverted position of the hairs of the internal surface of the leaf. At the bottom of a tube split open, the hairs are plainly discernible pointing downward; as the eye ranges upward, they gradually become shorter and attenuated, till at or just below the surface covered by the bait they are no longer perceptible to the naked eye nor to the most delicate touch. It is here that the fly cannot take a hold sufficiently strong to support itself, but falls. The in. ability of insects to crawl up against the points of the hairs I have often tested in the most satisfactory manner." From the last paragraph it may be inferred that Dr. Macbride did not suspect any inebriating property in the nectar, and in a closing note there is a conjecture of an impalpable loose powder in S. flava, at the place where the fly stands so unsteadily, and from which it is supposed to slide. We incline to take Mr. Grady's view of the case. The complete oblivion into which this paper and the whole subject had fallen is the more remarkable when it is seen that both are briefly but explicitly referred to in Elliott's book, with which botanists are familiar. It is not so wonderful that the far earlier allusion to these facts by the younger Bartram should have been overlooked or disregarded. With the genuine love of Nature and fondness for exploration, 'William Bartram did not inherit the simplicity of his father, the earliest native botanist of this country. Fine writing was his foible; and the preface to his well-known "Travels" (published at Philadelphia in 1791) is its full-blown illustration, sometimes perhaps deserving the epithet which he applies to the palms of Florida--that of pomposity. In this preface he declares that "all the Sarracenias are insect-catchers, and so is the Drosera rotundifolia. Whether the insects caught in their leaves, and which dissolve and mix with the fluid, serve for aliment or support to these kind of plants is doubtful," he thinks, but he should be credited with the suggestion. In one sentence he speaks of the quantities of insects which, "being invited down to sip the mellifluous exuvia from the interior surface of the tube, where they inevitably perish," being prevented from returning by the stiff hairs all pointing downward. This, if it refers to the sweet secretion, would place it below, and not, as it is, above the bristly surface, while the liquid below, charged with decomposing insects, is declared in an earlier sentence to be "cool and animating, limpid as the morning dew." Bartram was evidently writing from memory; and it is very doubtful if he ever distinctly recognized the sweet exudation which entices insects. Why should these plants take to organic food more than others? If we cannot answer the question, we may make a probable step toward it. For plants that are not parasitic, these, especially the sundews, have much less than the ordinary amount of chlorophyll--that is, of the universal leaf-green upon which the formation of organic matter out of inorganic materials depends. These take it instead of making it, to a certain extent. What is the bearing of these remarkable adaptations and operations upon doctrines of evolution? There seems here to be a field on which the specific creationist, the evolutionist with design, and the necessary evolutionist, may fight out an interesting, if not decisive, "triangular duel." XI INSECTIVOROUS AND CLIMBING PLANTS [XI-1] (The Nation, January 6 and 13, 1876) "Minerals grow; vegetables grow and live; animals grow, live, and feel;" this is the well-worn, not to say out-worn, diagnosis of the three kingdoms by Linnaeus. It must be said of it that the agreement indicated in the first couplet is unreal, and that the distinction declared in the second is evanescent. Crystals do not grow at all in the sense that plants and animals grow. On the other hand, if a response to external impressions by special movements is evidence of feeling, vegetables share this endowment with animals; while, if conscious feeling is meant, this can be affirmed only of the higher animals. What appears to remain true is, that the difference is one of successive addition. That the increment in the organic world is of many steps; that in the long series no absolute lines separate, or have always separated, organisms which barely respond to impressions from those which more actively and variously respond, and even from those that consciously so respond--this, as we all know, is what the author of the works before us has undertaken to demonstrate. Without reference here either to that part of the series with which man is connected, and in some sense or other forms a part of, or to that lower limbo where the two organic kingdoms apparently merge--or whence, in evolutionary phrase, they have emerged--Mr. Darwin, in the present volumes, directs our attention to the behavior of the highest plants alone. He shows that some (and he might add that all) of them execute movements for their own advantage, and that some capture and digest living prey. When plants are seen to move and to devour, what faculties are left that are distinctively animal? As to insectivorous or otherwise carnivorous plants, we have so recently here discussed this subject--before it attained to all this new popularity--that a brief account of Mr. Darwin's investigation may suffice.[XI-2] It is full of interest as a physiological research, and is a model of its kind, as well for the simplicity and directness of the means employed as for the clearness with which the results are brought out--results which any one may verify now that the way to them is pointed out, and which, surprising as they are, lose half their wonder in the ease and sureness with which they seem to have been reached. Rather more than half the volume is devoted to one subject, the round-leaved sundew (Drosera rotundifolia), a rather common plant in the northern temperate zone. That flies stick fast to its leaves, being limed by the tenacious seeming dew-drops which stud its upper face and margins, had long been noticed in Europe and in this country. We have heard hunters and explorers in our Northern woods refer with satisfaction to the fate which in this way often befalls one of their plagues, the black fly of early summer. And it was known to some observant botanists in the last century, although forgotten or discredited in this, that an insect caught on the viscid glands it has happened to alight upon is soon fixed by many more--not merely in consequence of its struggles, but by the spontaneous incurvation of the stalks of surrounding and untouched glands; and even the body of the leaf had been observed to incurve or become cup-shaped so as partly to involve the captive insect. Mr. Darwin's peculiar investigations not only confirm all this, but add greater wonders. They relate to the sensitiveness of these tentacles, as he prefers to call them, and the mode in which it is manifested; their power of absorption; their astonishing discernment of the presence of animal or other soluble azotized matter, even in quantities so minute as to rival the spectroscope--that most exquisite instrument of modern research--in delicacy; and, finally, they establish the fact of a true digestion, in all essential respects similar to that of the stomach of animals. First as to sensitiveness and movement. Sensitiveness is manifested by movement or change of form in response to an external impression. The sensitiveness in the sundew is all in the gland which surmounts the tentacle. To incite movement or other action, it is necessary that the gland itself should be reached. Anything laid on the surface of the viscid drop, the spherule of clear, glairy liquid which it secretes, produces no effect unless it sinks through to the gland; or unless the substance is soluble and reaches it in solution, which, in the case of certain substances, has the same effect. But the glands themselves do not move, nor does any neighboring portion of the tentacle. The outer and longer tentacles bend inward (toward the centre of the leaf) promptly, when the gland is irritated or stimulated, sweeping through an arc of 1800 or less, or more--the quickness and the extent of the inflection depending, in equally vigorous leaves, upon the amount of irritation or stimulation, and also upon its kind. A tentacle with a particle of raw meat on its gland sometimes visibly begins to bend in ten seconds, becomes strongly incurved in five minutes, and its tip reaches the centre of the leaf in half an hour; but this is a case of extreme rapidity. A particle of cinder, chalk, or sand, will also incite the bending, if actually brought in contact with the gland, not merely resting on the drop; but the inflection is then much less pronounced and more transient. Even a bit of thin human hair, only 1/8000 of an inch in length, weighing only the 1/78740 of a grain, and largely supported by the viscid secretion, suffices to induce movement; but, on the other hand, one or two momentary, although rude, touches with a hard object produce no effect, although a repeated touch or the slightest pressure, such as that of a gnat's foot, prolonged for a short time, causes bending. The seat of the movement is wholly or nearly confined to a portion of the lower part of the tentacle, above the base, where local irritation produces not the slightest effect. The movement takes place only in response to some impression made upon its own gland at the distant extremity, or upon other glands far more remote. For if one of these members suffers irritation the others sympathize with it. Very noteworthy is the correlation between the central tentacles, upon which an insect is most likely to alight, and these external and larger ones, which, in proportion to their distance from the centre, take the larger share in the movement. The shorter central ones do not move at all when a bit of meat, or a crushed fly, or a particle of a salt of ammonia, or the like, is placed upon them; but they transmit their excitation across the leaf to the surrounding tentacles on all sides; and they, although absolutely untouched, as they successively receive the mysterious impulse, bend strongly inward, just as they do when their own glands are excited. Whenever a tentacle bends in obedience to an impulse from its own gland, the movement is always toward the centre of the leaf; and this also takes place, as we have seen, when an exciting object is lodged at the centre. But when the object is placed upon either half of the leaf, the impulse radiating thence causes all the surrounding untouched tentacles to bend with precision toward the point of excitement, even the central tentacles, which are motionless when themselves charged, now responding to the call. The inflection which follows mechanical irritation or the presence of any inorganic or insoluble body is transient; that which follows the application of organic matter lasts longer, more or less, according to its nature and the amount; but sooner or later the tentacles resume their former position, their glands glisten anew with fresh secretion, and they are ready to act again. As to how the impulse is originated and propagated, and how the movements are made, comparatively simple as the structure is, we know as little as we do of the nature of nervous impulse and muscular motion. But two things Mr. Darwin has wellnigh made out, both of them by means and observations so simple and direct as to command our confidence, although they are contrary to the prevalent teaching. First, the transmission is through the ordinary cellular tissue, and not through what are called the fibrous or vascular bundles. Second, the movement is a vital one, and is effected by contraction on the side toward which the bending takes place, rather than by turgescent tension of the opposite side. The tentacle is pulled over rather than pushed over. So far all accords with muscular action. The operation of this fly-catching apparatus, in any case, is plain. If the insect alights upon the disk of the leaf, the viscid secretion holds it fast--at least, an ordinary fly is unable to escape--its struggles only increase the number of glands involved and the amount of excitement; this is telegraphed to the surrounding and successively longer tentacles, which bent over in succession, so that within ten to thirty hours, if the leaf is active and the fly large enough, every one of the glands (on the average, nearly two hundred in number) will be found applied to the body of the insect. If the insect is small, and the lodgment toward one side, only the neighboring tentacles may take part in the capture. If two or three of the strong marginal tentacles are first encountered, their prompt inflection carries the intruder to the centre, and presses it down upon the glands which thickly pave the floor; these notify all the surrounding tentacles of the capture, that they may share the spoil, and the fate of that victim is even as of the first. A bit of meat or a crushed insect is treated in the same way. This language implies that the animal matter is in some way or other discerned by the tentacles, and is appropriated. Formerly there was only a presumption of this, on the general ground that such an organization could hardly be purposeless. Yet, while such expressions were natural, if not unavoidable, they generally were used by those familiar with the facts in a half-serious, half-metaphorical sense. Thanks to Mr. Darwin's investigations, they may now be used in simplicity and seriousness. That the glands secrete the glairy liquid of the drop is evident, not only from its nature, but from its persistence through a whole day's exposure to a summer sun, as also from its renewal after it has been removed, dried up, or absorbed. That they absorb as well as secrete, and that the whole tentacle may be profoundly affected thereby, are proved by the different effects, in kind and degree, which follow the application of different substances. Drops of rain-water, like single momentary touches of a solid body, produce no effect, as indeed they could be of no advantage; but a little carbonate of ammonia in the water, or an infusion of meat, not only causes inflection, but promptly manifests its action upon the contents of the cells of which the tentacle is constructed. These cells are sufficiently transparent to be viewed under the microscope without dissection or other interference; and the change which takes place in the fluid contents of these cells, when the gland above has been acted upon, is often visible through a weak lens, or sometimes even by the naked eye, although higher powers are required to discern what actually takes place. This change, which Mr. Darwin discovered, and turns to much account in his researches, he terms "aggregation of the protoplasm." When untouched and quiescent, the contents appear as an homogeneous purple fluid. When the gland is acted upon, minute purple particles appear, suspended in the now colorless or almost colorless fluid; and this change appears first in the cells next the gland, and then in those next beneath, traveling down the whole length of the tentacle. When the action is slight, this appearance does not last long; the particles of "aggregated protoplasm redissolved, the process of redissolution traveling upward from the base of the tentacle to the gland in a reverse direction to that of the aggregation. Whenever the action is more prolonged or intense, as when a bit of meat or crushed fly, or a fitting solution, is left upon the gland, the aggregation proceeds further, so that the whole protoplasm of each cell condenses into one or two masses, or into a single mass which will often separate into two, which afterward reunite; indeed, they incessantly change their forms and positions, being never at rest, although their movements are rather slow. In appearance and movements they are very like amoebae and the white corpuscles of the blood. Their motion, along with the streaming movement of rotation in the layer of white granular protoplasm that flows along the walls of the cell, under the high powers of the microscope "presents a wonderful scene of vital activity." This continues while the tentacle is inflected or the gland fed by animal matter, but vanishes by dissolution when the work is over and the tentacle straightens. That absorption takes place, and matter is conveyed from cell to cell, is well made out, especially by the experiments with carbonate of ammonia. Nevertheless, this aggregation is not dependent upon absorption, for it equally occurs from mechanical irritation of the gland, and always accompanies inflection, however caused, though it may take place without it. This is also apparent from the astonishingly minute quantity of certain substances which suffices to produce sensible inflection and aggregation--such, for instance, as the 1/20000000 or even the 1/30000000 of a grain of phosphate or nitrate of ammonia! By varied experiments it was found that the nitrate of ammonia was more powerful than the carbonate, and the phosphate more powerful than the nitrate, this result being intelligible from the difference in the amount of nitrogen in the first two salts, and from the presence of phosphorus in the third. There is nothing surprising in the absorption of such extremely dilute solutions by a gland. As our author remarks: "All physiologists admit that the roots of plants absorb the salts of ammonia brought to them by the rain; and fourteen gallons of rain-water contain a grain of ammonia; therefore, only a little more than twice as much as in the weakest solution employed by me. The fact which appears truly wonderful is that the 1/20000000 of a grain of the phosphate of ammonia, including less than 1/30000000 of efficient matter (if the water of crystallization is deducted), when absorbed by a gland, should induce some change in it which leads to a motor impulse being transmitted down the whole length of the tentacle, causing its basal part to bend, often through an angle of 180 degrees." But odoriferous particles which act upon the nerves of animals must be infinitely smaller, and by these a dog a quarter of a mile to the leeward of a deer perceives his presence by some change in the olfactory nerves transmitted through them to the brain. When Mr. Darwin obtained these results, fourteen years ago, he could claim for Drosera a power and delicacy in the detection of minute quantities of a substance far beyond the resources of the most skillful chemist; but in a foot-note he admits that "now the spectroscope has altogether beaten Drosera; for, according to Bunsen and Kirchhoff, probably less than the 1/200000000 of a grain of sodium can be thus detected." Finally, that this highly-sensitive and active living organism absorbs, will not be doubted when it is proved to digest, that is, to dissolve otherwise insoluble animal matter by the aid of special secretions. That it does this is now past doubting. In the first place, when the glands are excited they pour forth an increased amount of the ropy secretion. This occurs directly when a bit of meat is laid upon the central glands; and the influence which they transmit to the long-stalked marginal glands causes them, while incurving their tentacles, to secrete more copiously long before they have themselves touched anything. The primary fluid, secreted without excitation, does not of itself digest. But the secretion under excitement changes in Nature and becomes acid. So, according to Schiff, mechanical irritation excites the glands of the stomach to secrete an acid. In both this acid appears to be necessary to, but of itself insufficient for, digestion. The requisite solvent, a kind of ferment called pepsin, which acts only in the presence of the acid, is poured forth by the glands of the stomach only after they have absorbed certain soluble nutritive substances of the food; then this pepsin promptly dissolves muscle, fibrine, coagulated albumen, cartilage, and the like. Similarly it appears that Drosera-glands, after irritation by particles of glass, did not act upon little cubes of albumen. But when moistened with saliva, or replaced by bits of roast-meat or gelatine, or even cartilage, which supply some soluble peptone-matter to initiate the process, these substances are promptly acted upon, and dissolved or digested; whence it is inferred that the analogy with the stomach holds good throughout, and that a ferment similar to pepsin is poured out under the stimulus of some soluble animal matter. But the direct evidence of this is furnished only by the related carnivorous plant, Dionaea, from which the secretions, poured out when digestion is about to begin, may be collected in quantity sufficient for chemical examination. In short, the experiments show "that there is a remarkable accordance in the power of digestion between the gastric juice of animals, with its pepsin and hydrochloric acid, and the secretion of Drosera, with its ferment and acid belonging to the acetic series. We can, therefore, hardly doubt that the ferment in both cases is closely similar, if not identically the same. That a plant and an animal should pour forth the same, or nearly the same, complex secretion, adapted for the same purpose of digestion, is a new and wonderful fact in physiology." There are one or two other species of sundew--one of them almost as common in Europe and North America as the ordinary round-leaved species--which act in the same way, except that, having their leaves longer in proportion to their breadth, their sides never curl inward, but they are much disposed to aid the action of their tentacles by incurving the tip of the leaf, as if to grasp the morsel. There are many others, with variously less efficient and less advantageously arranged insectivorous apparatus, which, in the language of the new science, may be either on the way to acquire something better, or of losing what they may have had, while now adapting themselves to a proper vegetable life. There is one member of the family (Drosophyllum Lusitanicum), an almost shrubby plant, which grows on dry and sunny hills in Portugal and Morocco--which the villagers call "the flycatcher," and hang up in their cottages for the purpose--the glandular tentacles of which have wholly lost their powers of movement, if they ever had any, but which still secrete, digest, and absorb, being roused to great activity by the contact of any animal matter. A friend of ours once remarked that it was fearful to contemplate the amount of soul that could be called forth in a dog by the sight of a piece of meat. Equally wonderful is the avidity for animal food manifested by these vegetable tentacles, that can "only stand and wait" for it. Only a brief chapter is devoted to Dionaea of North Carolina, the Venus's fly-trap, albeit, "from the rapidity and force of its movements, one of the most wonderful in the world." It is of the same family as the sundew; but the action is transferred from tentacles on the leaf to the body of the leaf itself, which is transformed into a spring-trap, closing with a sudden movement over the alighted insect. No secretion is provided beforehand either for allurement or detention; but after the captive is secured, microscopic glands within the surface of the leaf pour out an abundant gastric juice to digest it. Mrs. Glass's classical directions in the cook-book, "first catch your hare," are implicitly followed. Avoiding here all repetition or recapitulation of our former narrative, suffice it now to mention two interesting recent additions to our knowledge, for which we are indebted to Mr. Darwin. One is a research, the other an inspiration. It is mainly his investigations which have shown that the glairy liquid, which is poured upon and macerates the captured insect, accomplishes a true digestion; that, like the gastric juice of animals, it contains both a free acid and pepsin or its analogue, these two together dissolving albumen, meat, and the like. The other point relates to the significance of a peculiarity in the process of capture. When the trap suddenly incloses an insect which has betrayed its presence by touching one of the internal sensitive bristles, the closure is at first incomplete. For the sides approach in an arching way, surrounding a considerable cavity, and the marginal spine-like bristles merely intercross their tips, leaving intervening spaces through which one may look into the cavity beneath. A good idea may be had of it by bringing the two palms near together to represent the sides of the trap, and loosely interlocking the fingers to represent the marginal bristles or bars. After remaining some time in this position the closure is made complete by the margins coming into full contact, and the sides finally flattening down so as to press firmly upon the insect within; the secretion excited by contact is now poured out, and digestion begins. Why these two stages? Why should time be lost by this preliminary and incomplete closing? The query probably was never distinctly raised before, no one noticing anything here that needed explanation. Darwinian teleology, however, raises questions like this, and Mr. Darwin not only propounded the riddle but solved it. The object of the partial closing is to permit small insects to escape through the meshes, detaining only those plump enough to be worth the trouble of digesting. For naturally only one insect is caught at a time, and digestion is a slow business with Dionaeas, as with anacondas, requiring ordinarily a fortnight. It is not worth while to undertake it with a gnat when larger game may be had. To test this happy conjecture, Mr. Canby was asked, on visiting the Dionaeas in their native habitat, to collect early in the season a good series of leaves in the act of digesting naturally-caught insects. Upon opening them it was found that ten out of fourteen were engaged upon relatively large prey, and of the remaining four three had insects as large as ants, and one a rather small fly. "There be land-rats and water-rats" in this carnivorous sun-dew family. Aldrovanda, of the warmer parts of Europe and of India, is an aquatic plant, with bladdery leaves, which were supposed to be useful in rendering the herbage buoyant in water. But it has recently been found that the bladder is composed of two lobes, like the trap of its relative Dionaea, or the valves of a mussel-shell; that these open when the plant is in an active state, are provided with some sensitive bristles within, and when these are touched close with a quick movement. These water-traps are manifestly adapted for catching living creatures; and the few incomplete investigations that have already been made render it highly probably that they appropriate their prey for nourishment; whether by digestion or by mere absorption of decomposing animal matter, is uncertain. It is certainly most remarkable that this family of plants, wherever met with, and under the most diverse conditions and modes of life, should always in some way or other be predaceous and carnivorous. If it be not only surprising but somewhat confounding to our classifications that a whole group of plants should subsist partly by digesting animal matter and partly in the normal way of decomposing carbonic acid and producing the basis of animal matter, we have, as Mr. Darwin remarks, a counterpart anomaly in the animal kingdom. While some plants have stomachs, some animals have roots. "The rhizocephalous crustaceans do not feed like other animals by their mouths, for they are destitute of an alimentary canal, but they live by absorbing through root-like processes the juices of the animals on which they are parasitic." To a naturalist of our day, imbued with those ideas of the solidarity of organic Nature which such facts as those we have been considering suggest, the greatest anomaly of all would be that they are really anomalous or unique. Reasonably supposing, therefore, that the sundew did not stand alone, Mr. Darwin turned his attention to other groups of plants; and, first, to the bladderworts, which have no near kinship with the sundews, but, like the aquatic representative of that family, are provided with bladdery sacs, under water. In the common species of Utricularia or bladderwort, these little sacs, hanging from submerged leaves or branches, have their orifice closed by a lid which opens inwardly--a veritable trapdoor. It had been noticed in England and France that they contained minute crustacean animals. Early in the summer of 1874, Mr. Darwin ascertained the mechanism for their capture and the great success with which it is used. But before his account was written out, Prof. Cohn published an excellent paper on the subject in Germany; and Mrs. Treat, of Vineland, New Jersey, a still earlier one in this country--in the New York Tribune in the autumn of 1874. Of the latter, Mr. Darwin remarks that she "has been more successful than any other observer in witnessing the actual entrance of these minute creatures." They never come out, but soon perish in their prison, which receives a continued succession of victims, but little, if any, fresh air to the contained water. The action of the trap is purely mechanical, without evident irritability in the opening or shutting. There is no evidence nor much likelihood of proper digestion; indeed, Mr. Darwin found evidence to the contrary. But the more or less decomposed and dissolved animal matter is doubtless absorbed into the plant; for the whole interior of the sac is lined with peculiar, elongated and four-armed very thin-walled processes, which contain active protoplasm, and which were proved by experiment to "have the power of absorbing matter from weak solutions of certain salts of ammonia and urea, and from a putrid infusion of raw meat." Although the bladderworts "prey on garbage," their terrestrial relatives "live cleanly," as nobler plants should do, and have a good and true digestion. Pinguicula, or butterwort, is the representative of this family upon land. It gets both its Latin and its English name from the fatty or greasy appearance of the upper face of its broad leaves; and this appearance is due to a dense coat or pile of short-stalked glands, which secrete a colorless and extremely viscid liquid. By this small flies, or whatever may alight or fall upon the leaf, are held fast. These waifs might be useless or even injurious to the plant. Probably Mr. Darwin was the first to ask whether they might be of advantage. He certainly was the first to show that they probably are so. The evidence from experiment, shortly summed up, is, that insects alive or dead, and also other nitrogenous bodies, excite these glands to increased secretion; the secretion then becomes acid, and acquires the power of dissolving solid animal substances--that is, the power of digestion in the manner of Drosera and Dionaea. And the stalks of their glands under the microscope give the same ocular evidence of absorption. The leaves of the butterwort are apt to have their margins folded inward, like a rim or hem. Taking young and vigorous leaves to which hardly anything had yet adhered, and of which the margins were still flat, Mr. Darwin set within one margin a row of small flies. Fifteen hours afterward this edge was neatly turned inward, partly covering the row of flies, and the surrounding glands were secreting copiously. The other edge remained flat and unaltered. Then he stuck a fly to the middle of the leaf just below its tip, and soon both margins infolded, so as to clasp the object. Many other and varied experiments yielded similar results. Even pollen, which would not rarely be lodged upon these leaves, as it falls from surrounding wind-fertilized plants, also small seeds, excited the same action, and showed signs of being acted upon. "We may therefore conclude," with Mr. Darwin, "that Pinguicula vulgaris, with its small roots, is not only supported to a large extent by the extraordinary number of insects which it habitually captures, but likewise draws some nourishment from the pollen, leaves, and seeds, of other plants which often adhere to its leaves. It is, therefore, partly a vegetable as well as an animal feeder." What is now to be thought of the ordinary glandular hairs which render the surface of many and the most various plants extremely viscid? Their number is legion. The Chinese primrose of common garden and house culture is no extraordinary instance; but Mr. Francis Darwin, counting those on a small space measured by the micrometer, estimated them at 65,371 to the square inch of foliage, taking in both surfaces of the leaf, or two or three millions on a moderate-sized specimen of this small herb. Glands of this sort were loosely regarded as organs for excretion, without much consideration of the question whether, in vegetable life, there could be any need to excrete, or any advantage gained by throwing off such products; and, while the popular name of catch-fly, given to several common species of Silene, indicates long familiarity with the fact, probably no one ever imagined that the swarms of small insects which perish upon these sticky surfaces were ever turned to account by the plant. In many such cases, no doubt they perish as uselessly as when attracted into the flame of a candle. In the tobacco-plant, for instance, Mr. Darwin could find no evidence that the glandular hairs absorb animal matter. But Darwinian philosophy expects all gradations between casualty and complete adaptation. It is most probable that any thin-walled vegetable structure which secretes may also be capable of absorbing under favorable conditions. The myriads of exquisitely-constructed glands of the Chinese primrose are not likely to be functionless. Mr. Darwin ascertained by direct experiment that they promptly absorb carbonate of ammonia, both in watery solution and in vapor. So, since rain-water usually contains a small percentage of ammonia, a use for these glands becomes apparent--one completely congruous with that of absorbing any animal matter, or products of its decomposition, which may come in their way through the occasional entanglement of insects in their viscid secretion. In several saxifrages--not very distant relatives of Drosera--the viscid glands equally manifested the power of absorption. To trace a gradation between a simply absorbing hair with a glutinous tip, through which the plant may perchance derive slight contingent advantage, and the tentacles of a sundew, with their exquisite and associated adaptations, does not much lessen the wonder nor explain the phenomena. After all, as Mr. Darwin modestly concludes, "we see how little has been made out in comparison with what remains unexplained and unknown." But all this must be allowed to be an important contribution to the doctrine of the gradual acquirement of uses and functions, and hardly to find conceivable explanation upon any other hypothesis. There remains one more mode in which plants of the higher grade are known to prey upon animals; namely, by means of pitchers, urns, or tubes, in which insects and the like are drowned or confined, and either macerated or digested. To this Mr. Darwin barely alludes on the last page of the present volume. The main facts known respecting the American pitcher-plants have, as was natural, been ascertained in this country; and we gave an abstract, two years ago, of our then incipient knowledge. Much has been learned since, although all the observations have been of a desultory character. If space permitted, an instructive narrative might be drawn up, as well of the economy of the Sarracenias as of how we came to know what we do of it. But the very little we have room for will be strictly supplementary to our former article. The pitchers of our familiar Northern Sarracenia, which is likewise Southern, are open-mouthed; and, although they certainly secrete some liquid when young, must derive most of the water they ordinarily contain from rain. How insects are attracted is unknown, but the water abounds with their drowned bodies and decomposing remains. In the more southern S. flava, the long and trumpet-shaped pitchers evidently depend upon the liquid which they themselves secrete, although at maturity, when the hood becomes erect, rain may somewhat add to it. This species, as we know, allures insects by a peculiar sweet exudation within the orifice; they fall in and perish, though seldom by drowning, yet few are able to escape; and their decomposing remains accumulate in the narrow bottom of the vessel. Two other long-tubed species of the Southern States are similar in these respects. There is another, S. psittacina, the parrot-headed species, remarkable for the cowl-shaped hood so completely inflexed over the mouth of the small pitcher that no rain can possibly enter. Little is known, however, of the efficiency of this species as a fly-catcher; but its conformation has a morphological interest, leading up, as it does, to the Californian type of pitcher presently to be mentioned. But the remaining species, S. variolaris, is the most wonderful of our pitcher-plants in its adaptations for the capture of insects. The inflated and mottled lid or hood overarches the ample orifice of the tubular pitcher sufficiently to ward off the rain, but not to obstruct the free access of flying insects. Flies, ants, and most insects, glide and fall from the treacherous smooth throat into the deep well below, and never escape. They are allured by a sweet secretion just within the orifice-- which was discovered and described long ago, and the knowledge of it wellnigh forgotten until recently. And, finally, Dr. Mellichamp, of South Carolina, two years ago made the capital discovery that, during the height of the season, this lure extends from the orifice down nearly to the ground, a length of a foot or two, in the form of a honeyed line or narrow trail on the edge of the wing-like border which is conspicuous in all these species, although only in this one, so far as known, turned to such account. Here, one would say, is a special adaptation to ants and such terrestrial and creeping insects. Well, long before this sweet trail was known, it was remarked by the late Prof. Wyman and others that the pitchers of this species, in the savannahs of Georgia and Florida, contain far more ants than they do of all other insects put together. Finally, all this is essentially repeated in the peculiar Californian pitcher-plant (Darlingtonia), a genus of the same natural family, which captures insects in great variety, enticing them by a sweetish secretion over the whole inside of the inflated hood and that of a curious forked appendage, resembling a fish-tail, which overhangs the orifice. This orifice is so concealed that it can be seen and approached only from below, as if--the casual observer might infer--to escape visitation. But dead insects of all kinds, and their decomposing remains, crowd the cavity and saturate the liquid therein contained, enticed, it is said, by a peculiar odor, as well as by the sweet lure which is at some stages so abundant as to drip from the tips of the overhanging appendage. The principal observations upon this pitcher-plant in its native habitat have been made by Mrs. Austin, and only some of the earlier ones have thus far been published by Mr. Canby. But we are assured that in this, as in the Sarracenia variolaris, the sweet exudation extends at the proper season from the orifice down the wing nearly to the ground, and that ants follow this honeyed pathway to their destruction. Also, that the watery liquid in the pitcher, which must be wholly a secretion, is much increased in quantity after the capture of insects. It cannot now well be doubted that the animal matter is utilized by the plant in all these cases, although most probably only after maceration or decomposition. In some of them even digestion, or at least the absorption of undecomposed soluble animal juices, may be suspected; but there is no proof of it. But, if pitchers of the Sarracenia family are only macerating vessels, those of Nepenthes--the pitchers of the Indian Archipelago, familiar in conservatories--seem to be stomachs. The investigations of the President of the Royal Society, Dr. Hooker, although incomplete, wellnigh demonstrate that these not only allure insects by a sweet secretion at the rim and upon the lid of the cup, but also that their capture, or the presence of other partly soluble animal matter, produces an increase and an acidulation of the contained watery liquid, which thereupon becomes capable of acting in the manner of that of Drosera and Dionaea, dissolving flesh, albumen, and the like. After all, there never was just ground for denying to vegetables the use of animal food. The fungi are by far the most numerous family of plants, and they all live upon organic matter, some upon dead and decomposing, some upon living, some upon both; and the number of those that feed upon living animals is large. Whether these carnivorous propensities of higher plants which so excite our wonder be regarded as survivals of ancestral habits, or as comparatively late acquirements, or even as special endowments, in any case what we have now learned of them goes to strengthen the conclusion that the whole organic world is akin. The volume upon "The Movements and Habits of Climbing Plants" is a revised and enlarged edition of a memoir communicated to the Linnaean Society in 1865, and published in the ninth volume of its Journal. There was an extra impression, but, beyond the circle of naturalists, it can hardly have been much known at first-hand. Even now, when it is made a part of the general Darwinian literature, it is unlikely to be as widely read as the companion volume which we have been reviewing; although it is really a more readable book, and well worthy of far more extended notice at our hands than it can now receive. The reason is obvious. It seems as natural that plants should climb as it does unnatural that any should take animal food. Most people, knowing that some plants "twine with the sun," and others "against the sun," have an idea that the sun in some way causes the twining; indeed, the notion is still fixed in the popular mind that the same species twines in opposite directions north and south of the equator. Readers of this fascinating treatise will learn, first of all, that the sun has no influence over such movements directly, and that its indirect influence is commonly adverse or disturbing, except the heat, which quickens vegetable as it does animal life. Also, that climbing is accomplished by powers and actions as unlike those generally predicated of the vegetable kingdom as any which have been brought to view in the preceding volume. Climbing plants "feel" as well as "grow and live;" and they also manifest an automatism which is perhaps more wonderful than a response by visible movement to an external irritation. Nor do plants grow up their supports, as is unthinkingly supposed; for, although only growing or newly-grown parts act in climbing, the climbing and the growth are entirely distinct. To this there is one exception--an instructive one, as showing how one action passes into another, and how the same result may be brought about in different ways--that of stems which climb by rootlets, such as of ivy and trumpet-creeper. Here the stem ascends by growth alone, taking upward direction, and is fixed by root-lets as it grows. There is no better way of climbing walls, precipices, and large tree-trunks. But small stems and similar supports are best ascended by twining; and this calls out powers of another and higher order. The twining stem does not grow around its support, but winds around it, and it does this by a movement the nature of which is best observed in stems which have not yet reached their support, or have overtopped it and stretched out beyond it. Then it may be seen that the extending summit, reaching farther and farther as it grows, is making free circular sweeps, by night as well as by day, and irrespective of external circumstances, except that warmth accelerates the movement, and that the general tendency of young stems to bend toward the light may, in case of lateral illumination, accelerate one-half the circuit while it equally retards the other. The arrest of the revolution where the supporting body is struck, while the portion beyond continues its movement, brings about the twining. As to the proximate cause of this sweeping motion, a few simple experiments prove that it results from the bowing or bending of the free summit of the stem into a more or less horizontal position (this bending being successively to every point of the compass, through an action which circulates around the stem in the direction of the sweep), and of the consequent twining, i.e., "with the sun," or with the movement of the hands of a watch, in the hop, or in the opposite direction in pole-beans and most twiners. Twining plants, therefore, ascend trees or other stems by an action and a movement of their own, from which they derive advantage. To plants liable to be overshadowed by more robust companions, climbing is an economical method of obtaining a freer exposure to light and air with the smallest possible expenditure of material. But twiners have one disadvantage: to rise ten feet they must produce fifteen feet of stem or thereabouts, according to the diameter of the support, and the openness or closeness of the coil. A rootlet-climber saves much in this respect, but has a restricted range of action, and other disadvantages. There are two other modes, which combine the utmost economy of material with freer range of action. There are, in the first place, leaf-climbers of various sorts, agreeing only in this, that the duty of laying hold is transferred to the leaves, so that the stem may rise in a direct line. Sometimes the blade or leaflets, or some of them, but more commonly their slender stalks, undertake the work, and the plant rises as a boy ascends a tree, grasping first with one hand or arm, then with the other. Indeed, the comparison, like the leaf-stalk, holds better than would be supposed; for the grasping of the latter is not the result of a blind groping in all directions by a continuous movement, but of a definite sensitiveness which acts only upon the occasion. Most leaves make no regular sweeps; but when the stalks of a leaf-climbing species come into prolonged contact with any fitting extraneous body, they slowly incurve and make a turn around it, and then commonly thicken and harden until they attain a strength which may equal that of the stem itself. Here we have the faculty of movement to a definite end, upon external irritation, of the same nature with that displayed by Dionaea and Drosera, although slower for the most part than even in the latter. But the movement of the hour-hand of the clock is not different in nature or cause from that of the second-hand. Finally--distribution of office being, on the whole, most advantageous and economical, and this, in the vegetable kingdom, being led up to by degrees--we reach, through numerous gradations, the highest style of climbing plants in the tendril-climber. A tendril morphologically, is either a leaf or branch of stem, or a portion of one, specially organized for climbing. Some tendrils simply turn away from light, as do those of grape-vines, thus taking the direction in which some supporting object is likely to be encountered; most are indifferent to light; and many revolve in the manner of the summit of twining stems. As the stems which bear these highly-endowed tendrils in many cases themselves also revolve more or less, though they seldom twine, their reach is the more extensive; and to this endowment of automatic movement most tendrils add the other faculty, that of incurving and coiling upon prolonged touch, or even brief contact, in the highest degree. Some long tendrils, when in their best condition, revolve so rapidly that the sweeping movement may be plainly seen; indeed, we have seen a quarter-circuit in a Passiflora sicyoides accomplished in less than a minute, and the half-circuit in ten minutes; but the other half (for a reason alluded to in the next paragraph) takes a much longer time. Then, as to the coiling upon contact, in the case first noticed in this country,[XI-3] in the year 1858, which Mr. Darwin mentions as having led him into this investigation, the tendril of Sicyos was seen to coil within half a minute after a stroke with the hand, and to make a full turn or more within the next minute; furnishing ocular evidence that tendrils grasp and coil in virtue of sensitiveness to contact, and, one would suppose, negativing Sachs's recent hypothesis that all these movements are owing "to rapid growth on the side opposite to that which becomes concave"--a view to which Mr. Darwin objects, but not so strongly as he might. The tendril of this sort, on striking some fitting object, quickly curls round and firmly grasps it; then, after some hours, one side shortening or remaining short in proportion to the other, it coils into a spire, dragging the stem up to its support, and enabling the next tendril above to secure a readier hold. In revolving tendrils perhaps the most wonderful adaptation is that by which they avoid attachment to, or winding themselves upon, the ascending summit of the stem that bears them. This they would inevitably do if they continued their sweep horizontally. But when in its course it nears the parent stem the tendril moves slowly, as if to gather strength, then C.~ stiffens and rises into an erect position parallel with it, and C so passes by the dangerous point; after which it comes rapidly down to the horizontal position, in which it moves until it again approaches and again avoids the impending obstacle. Climbing plants are distributed throughout almost all the natural orders. In some orders climbing is the rule, in most it is the exception, occurring only in certain genera. The tendency of stems to move in circuits--upon which climbing more commonly depends, and out of which it is conceived to have been educed--is manifested incipiently by many a plant which does not climb. Of those that do there are all degrees, from the feeblest to the most efficient, from those which have no special adaptation to those which have exquisitely-endowed special organs for climbing. The conclusion reached is, that the power "is inherent, though undeveloped, in almost every plant;" "that climbing plants have utilized and perfected a widely-distributed and incipient capacity, which, as far as we can see, is of no service to ordinary plants." Inherent powers and incipient manifestations, useless to their possessors but useful to their successors--this, doubtless, is according to the order of Nature; but it seems to need something more than natural selection to account for it. XII DURATION AND ORIGINATION OF RACE AND SPECIES-- IMPORT OF SEXUAL REPRODUCTION I Do Varieties wear out, or tend to wear out? (New York Tribune, and American Journal of Science and the Arts, February, 1875) This question has been argued from time to time for more than half a century, and is far from being settled yet. Indeed, it is not to be settled either way so easily as is sometimes thought. The result of a prolonged and rather lively discussion of the topic about forty years ago in England, in which Lindley bore a leading part on the negative side, was, if we rightly remember, that the nays had the best of the argument. The deniers could fairly well explain away the facts adduced by the other side, and evade the force of the reasons then assigned to prove that varieties were bound to die out in the course of time. But if the case were fully re-argued now, it is by no means certain that the nays would win it. The most they could expect would be the Scotch verdict, "not proven." And this not because much, if any, additional evidence of the actual wearing out of any variety has turned up since, but because a presumption has been raised under which the evidence would take a bias the other way. There is now in the minds of scientific men some reason to expect that certain varieties would die out in the long run, and this might have an important influence upon the interpretation of the facts. Curiously enough, however, the recent discussions to which our attention has been called seem, on both sides, to have overlooked this. But, first of all, the question needs to be more specifically stated. There are varieties and varieties. They may, some of them, disappear or deteriorate, but yet not wear out--not come to an end from any inherent cause. One might even say, the younger they are the less the chance of survival unless well cared for. They may be smothered out by the adverse force of superior numbers; they are even more likely to be bred out of existence by unprevented cross-fertilization, or to disappear from mere change of fashion. The question, however, is not so much about reversion to an ancestral state, or the falling off of a high-bred stock into an inferior condition. Of such cases it is enough to say that, when a variety or strain, of animal or vegetable, is led up to unusual fecundity or of size or product of any organ, for our good, and not for the good of the plant or animal itself, it can be kept so only by high feeding and exceptional care; and that with high feeding and artificial appliances comes vastly increased liability to disease, which may practically annihilate the race. But then the race, like the bursted boiler, could not be said to wear out, while if left to ordinary conditions, and allowed to degenerate back into a more natural if less useful state, its hold on life would evidently be increased rather than diminished. As to natural varieties or races under normal conditions, sexually propagated, it could readily be shown that they are neither more nor less likely to disappear from any inherent cause than the species from which they originated. Whether species wear out, i.e., have their rise, culmination, and decline, from any inherent cause, is wholly a geological and very speculative problem, upon which, indeed, only vague conjectures can be offered. The matter actually under discussion concerns cultivated domesticated varieties only, and, as to plants, is covered by two questions. First, Will races propagated by seed, being so fixed that they come true to seed, and purely bred (not crossed with any other sort), continue so indefinitely, or will they run out in time--not die out, perhaps, but lose their distinguishing characters? Upon this, all we are able to say is that we know no reason why they should wear out or deteriorate from any inherent cause. The transient existence or the deterioration and disappearance of many such races are sufficiently accounted for otherwise; as in the case of extraordinarily exuberant varieties, such as mammoth fruits or roots, by increased liability to disease, already adverted to, or by the failure of the high feeding they demand. A common cause, in ordinary cases, is cross-breeding, through the agency of wind or insects, which is difficult to guard against. Or they go out of fashion and are superseded by others thought to be better, and so the old ones disappear. Or, finally, they may revert to an ancestral form. As offspring tend to resemble grandparents almost as much as parents, and as a line of close-bred ancestry is generally prepotent, so newly-originated varieties have always a tendency to reversion. This is pretty sure to show itself in some of the progeny of the earlier generations, and the breeder has to guard against it by rigid selection. But the older the variety is--that is, the longer the series of generations in which it has come true from seed--the less the chance of reversion: for now, to be like the immediate parents, is also to be like a long line of ancestry; and so all the influences concerned--- that is, both parental and ancestral heritability--act in one and the same direction. So, since the older a race is the more reason it has to continue true, the presumption of the unlimited permanence of old races is very strong. Of course the race itself may give off new varieties; but that is no interference with the vitality of the original stock. If some of the new varieties supplant the old, that will not be because the unvaried stock is worn out or decrepit with age, but because in wild Nature the newer forms are better adapted to the surroundings, or, under man's care, better adapted to his wants or fancies. The second question, and one upon which the discussion about the wearing out of varieties generally turns, is, Will varieties propagated from buds, i.e., by division, grafts, bulbs, tubers, and the like, necessarily deteriorate and die out? First, Do they die out as a matter of fact? Upon this, the testimony has all along been conflicting. Andrew Knight was sure that they do, and there could hardly be a more trustworthy witness. "The fact," he says, fifty years ago, "that certain varieties of some species of fruit which have been long cultivated cannot now be made to grow in the same soils and under the same mode of management, which was a century ago so perfectly successful, is placed beyond the reach of controversy. Every experiment which seemed to afford the slightest prospect of success was tried by myself and others to propagate the old varieties of the apple and pear which formerly constituted the orchards of Herefordshire, without a single healthy or efficient tree having been obtained; and I believe all attempts to propagate these varieties have, during some years, wholly ceased to be made." To this it was replied, in that and the next generation, that cultivated vines have been transmitted by perpetual division from the time of the Romans, and that several of the sorts, still prized and prolific, are well identified, among them the ancient Graecula, considered to be the modern Corinth or currant grape, which has immemorially been seedless; that the old nonpareil apple was known in the time of Queen Elizabeth; that the white beurre pears of France have been propagated from the earliest times; and that golden pippins, St. Michael pears, and others said to have run out, were still to be had in good condition. Coming down to the present year, a glance through the proceedings of pomological societies, and the debates of farmers' clubs, brings out the same difference of opinion. The testimony is nearly equally divided. Perhaps the larger number speak of the deterioration and failure of particular old sorts; but when the question turns on "wearing out," the positive evidence of vigorous trees and sound fruits is most telling. A little positive testimony outweighs a good deal of negative. This cannot readily be explained away, while the failures may be, by exhaustion of soil, incoming of disease, or alteration of climate or circumstances. On the other hand, it may be urged that, if a variety of this sort is fated to become decrepit and die out, it is not bound to die out all at once, and everywhere at the same time. It would be expected first to give way wherever it is weakest, from whatever cause. This consideration has an important bearing upon the final question, Are old varieties of this kind on the way to die out on account of their age or any inherent limit of vitality? Here, again, Mr. Knight took an extreme view. In his essay in the "Philosophical Transactions," published in the year 1810, he propounded the theory, not merely of a natural limit to varieties from grafts and cuttings, but even that they would not survive the natural term of the life of the seedling trees from which they were originally taken. Whatever may have been his view of the natural term of the life of a tree, and of a cutting being merely a part of the individual that produced it, there is no doubt that he laid himself open to the effective replies which were made from all sides at the time, and have lost none of their force since. Weeping-willows, bread-fruits, bananas, sugar-cane, tiger-lilies, Jerusalem artichokes, and the like, have been propagated for a long while in this way, without evident decadence. Moreover, the analogy upon which his hypothesis is founded will not hold. Whether or not one adopts the present writer's conception, that individuality is not actually reached or maintained in the vegetable world, it is clear enough that a common plant or tree is not an individual in the sense that a horse or man, or any one of the higher animals, is--that it is an individual only in the sense that a branching zoophyte or mass of coral is. Solvitur crescendo: the tree and the branch equally demonstrate that they are not individuals, by being divided with impunity and advantage, with no loss of life, but much increase. It looks odd enough to see a writer like Mr. Sisley reproducing the old hypothesis in so bare a form as this: "I am prepared to maintain that varieties are individuals, and that as they are born they must die, like other individuals . . . We know that oaks, Sequoias, and other trees, live several centuries, but how many we do not exactly know. But that they must die, no one in his senses will dispute." Now, what people in their senses do dispute is, not that the tree will die, but that other trees, established from its cuttings, will die with it. But does it follow from this that non-sexually-propagated varieties are endowed with the same power of unlimited duration that is possessed by varieties and species propagated sexually--i.e., by seed? Those who think so jump too soon at their conclusion. For, as to the facts, it is not enough to point out the diseases or the trouble in the soil or the atmosphere to which certain old fruits are succumbing, nor to prove that a parasitic fungus (Peronospora infestans) is what is the matter with potatoes. For how else would constitutional debility, if such there be, more naturally manifest itself than in such increased liability or diminished resistance to such attacks? And if you say that, anyhow, such varieties do not die of old age--meaning that each individual attacked does not die of old age, but of manifest disease--it may be asked in return, what individual man ever dies of old age in any other sense than of a similar inability to resist invasions which in earlier years would have produced no noticeable effect? Aged people die of a slight cold or a slight accident, but the inevitable weakness that attends old age is what makes these slight attacks fatal. Finally, there is a philosophical argument which tells strongly for some limitation of the duration of non-sexually propagated forms, one that probably Knight never thought of, but which we should not have expected recent writers to overlook. When Mr. Darwin announced the principle that cross-fertilization between the individuals of a species is the plan of Nature, and is practically so universal that it fairly sustains his inference that no hermaphrodite species continually self-fertilized would continue to exist, he made it clear to all who apprehend and receive the principle that a series of plants propagated by buds only must have weaker hold of life than a series reproduced by seed. For the former is the closest possible kind of close breeding. Upon this ground such varieties may be expected ultimately to die out; but "the mills of the gods grind so exceeding slow" that we cannot say that any particular grist has been actually ground out under human observation. If it be asked how the asserted principle is proved or made probable, we can here merely say that the proof is wholly inferential. But the inference is drawn from such a vast array of facts that it is wellnigh irresistible. It is the legitimate explanation of those arrangements in Nature to secure cross-fertilization in the species, either constantly or occasionally, which are so general, so varied and diverse, and, we may add, so exquisite and wonderful, that, once propounded, we see that it must be true.* What else, indeed, is the meaning and * Here an article would be in place, explaining the arrangements in Nature for cross-fertilization, or wide-breeding, in plants, through the agency, sometimes of the winds, but more commonly of insects; the more so, since the development of the principle, the appreciation of its importance, and its confirmation by abundant facts, are mainly due to Mr. Darwin. But our reviews and notices of his early work "On the Contrivances in Nature for the Fertilization of Orchids by Means of Insects, in 1862, and his various subsequent papers upon other parts of this subject, are either too technical or too fragmentary or special to be here reproduced. Indeed, a popular essay is now hardly needed, since the topic has been fully presented, of late years, in the current popular and scientific journals, and in common educational works and text-books, so that it is in the way of becoming a part--and a most inviting part--of ordinary botanical instruction. use of sexual reproduction? Not simply increase of numbers; for that is otherwise effectually provided for by budding propagation in plants and many of the lower animals. There are plants, indeed, of the lower sort (such as diatoms), in which the whole multiplication takes place in this way, and with great rapidity. These also have sexual reproduction; but in it two old individuals are always destroyed to make a single new one! Here propagation diminishes the number of individuals fifty per cent. Who can suppose that such a costly process as this, and that all the exquisite arrangements for cross-fertilization in hermaphrodite plants, do not subserve some most important purpose? How and why the union of two organisms, or generally of two very minute portions of them, should reenforce vitality, we do not know, and can hardly conjecture. But this must be the meaning of sexual reproduction. The conclusion of the matter, from the scientific point of view, is, that sexually-propagated varieties or races, although liable to disappear through change, need not be expected to wear out, and there is no proof that they do; but, that non-sexually propagated varieties, though not especially liable to change, may theoretically be expected to wear out, but to be a very long time about it. II Do Species wear out? and if not, why not? The question we have just been considering was merely whether races are, or may be, as enduring as species. As to the inherently unlimited existence of species themselves, or the contrary, this, as we have said, is a geological and very speculative problem. Not a few geologists and naturalists, however, have concluded, or taken for granted, that species have a natural term of existence--that they culminate, decline, and disappear through exhaustion of specific vitality, or some equivalent internal cause. As might be expected from the nature of the inquiry, the facts which bear upon the question are far from decisive. If the fact that species in general have not been interminable, but that one after another in long succession has become extinct, would seem to warrant this conclusion, the persistence through immense periods of no inconsiderable number of the lower forms of vegetable and animal life, and of a few of the higher plants from the Tertiary period to the present, tells even more directly for the limitless existence of species. The disappearance is quite compatible with the latter view; while the persistence of any species is hardly explicable upon any other. So that, even under the common belief of the entire stability and essential inflexibility of species, extinction is more likely to have been accidental than predetermined, and the doctrine of inherent limitation is unsupported by positive evidence. On the other hand, it is an implication of the Darwinian doctrine that species are essentially unlimited in existence. When they die out--as sooner or later any species may--the verdict must be accidental death, under stress of adverse circumstances, not exhaustion of vitality; and, commonly, when the species seems to die out, it will rather have suffered change. For the stock of vitality which enables it to vary and. survive in changed forms under changed circumstances must be deemed sufficient for a continued unchanged existence under unaltered conditions. And, indeed, the advancement from simpler to more complex, which upon the theory must have attended the diversification, would warrant or require the supposition of increase instead of diminution of power from age to age. The only case we call to mind which, under the Darwinian view, might be interpreted as a dying out from inherent causes, is that of a species which refuses to vary, and thus lacks the capacity of adaptation to altering conditions. Under altering conditions, this lack would be fatal. But this would be the fatality of some species or form in particular, not of species or forms generally, which, for the most part, may and do vary sufficiently, and in varying survive, seemingly none the worse, but rather the better, for their long tenure of life. The opposite idea, however, is maintained by M. Naudin,[XII-1] in a detailed exposition of his own views of evolution, which differ widely from those of Darwin in most respects, and notably in excluding that which, in our day, gives to the subject its first claim to scientific (as distinguished from purely speculative) attention; namely, natural selection. Instead of the causes or operations collectively personified under this term, and which are capable of exact or probable appreciation, M. Naudin invokes "the two principles of rhythm and of the decrease of forces in Nature." He is a thorough evolutionist, starting from essentially the same point with Darwin; for he conceives of all the forms or species of animals and plants "comme tire tout entier d'un protoplasma primordial, uniform, instable, eminemment plastique." Also in "l'integration croissante de la force evolutive a mesure qu'elle se partage dans les formes produites, et la decroissance proportionelle de la plasticite de ces formes a mesure qu'elles s'eloignent davantage de leur origine, et qu'elles sont mieux arretees." As they get older, they gain in fixity through the operation of the fundamental law of inheritance; but the species, like the individual, loses plasticity and vital force. To continue in the language of the original: "C'est dire qu'il y a eu, pour l'ensemble du monde organique, une periode de formation ou tout etait changeant et mobile, une phase analogue a la vie embryonnaire et a la jeunesse de chaque etre particulier; et qu'a cet age de mobilite et de croissance a succede une periode de stabilite, au moins relative, une sorte d'age adulte, ou la force evolutive, ayant acheve son oeuvre, n'est plus occupee qu'a la maintenir, sans pouvoir produire d'organismes nouveaux. Limitee en quantite, comme toutes les forces en jeu dans une planete ou dans un systeme sideral tout entier, cette force n'a pu accomplir qu'un travail limite; et du meme qu'un organisme, animal ou vegetal, ne croit pas indefiniment et qu'il s'arrete a des proportions que rien ne peut faire depasser, de meme aussi l'organisme total de la nature s'est arrete a un etat d'equilibre, dont la duree, selon toutes vraisemblances, doit etre beaucoup plus longue que celle de la phase de developpement et de croissance. A fixed amount of "evolutive force" is given, to begin with. At first enormous, because none has been used up in work, it is necessarily enfeebled in the currents into which the stream divides, and the narrower and narrower channels in which it flows with slowly-diminishing power. Hence the limited although very unequal duration of all individuals, of all species, and of all types of organization. A multitude of forms have disappeared already, and the number of species, far from increasing, as some have believed, must, on the contrary, be diminishing. Some species, no doubt, have suffered death by violence or accident, by geological changes, local alteration of the conditions, or the direct or indirect attacks of other species; but these have only anticipated their fate, for M. Naudin contends that most of the extinct species have died a natural death from exhaustion of force, and that all the survivors are on the way to it. The great timepiece of Nature was wound up at the beginning, and is running down. In the earlier stages of great plasticity and exuberant power, diversification took place freely, but only in definite lines, and species and types multiplied. As the power of survival is inherently limited, still more the power of change: this diminishes in time, if we rightly apprehend the idea, partly through the waning of vital force, partly through the fixity acquired by heredity--like producing like, the more certainly in proportion to the length and continuity of the ancestral chain And so the small variations of species which we behold are the feeble remnants of the pristine plasticity and an exhausted force.[XII-2] This force of variation or origination of forms has acted rhythmically or intermittently, because each movement was the result of the rupture of an equilibrium, the liberation of a force which till then was retained in a potential state by some opposing force or obstacle, overcoming which it passes to a new equilibrium and so on Hence alternations of dynamic activity and static repose, of origination of species and types, alternated with periods of stability or fixity. The timepiece does not run down regularly, but "la force procede par saccades; et . . . par pulsations d'autant plus energiques que la nature etait plus pres de son commencement." Such is the hypothesis. For a theory of evolution, this is singularly unlike Darwin's in most respects, and particularly in the kind of causes invoked and speculations indulged in. But we are not here to comment upon it beyond the particular point under consideration, namely, its doctrine of the inherently limited duration of species. This comes, it will be noticed, as a deduction from the modern physical doctrine of the equivalence of force. The reasoning is ingenious, but, if we mistake not, fallacious. To call that "evolutive force" which produces the change of one kind of plant or animal into another, is simple and easy, but of little help by way of explanation. To homologize it with physical force, as M. Naudin's argument requires, is indeed a step, and a hardy one; but it quite invalidates the argument. For, if the "evolutive force" is a part of the physical force of the universe, of which, as he reminds us, the sum is fixed and the tendency is toward a stable equilibrium in which all change is to end, then this evolutive was derived from the physical force; and why not still derivable from it? What is to prevent its replenishment in vegetation, pari passu with that great operation in which physical force is stored up in vegetable organisms, and by the expenditure or transformation of which their work, and that of all animals, is carried on? Whatever be the cause (if any there be) which determines the decadence and death of species, one cannot well believe that it is a consequence of a diminution of their proper force by plant-development and division; for instance, that the sum of what is called vital force in a full-grown tree is not greater, instead of less, than that in the seeding, and in the grove greater than in the single parental tree. This power, if it be properly a force, is doubtless as truly derived from the sunbeam as is the power which the plant and animal expend in work. Here, then, is a source of replenishment as lasting as the sun itself, and a ground--so far as a supply of force is concerned--for indefinite duration. For all that any one can mean by the indefinite existence of species is, that they may (for all that yet appears) continue while the external conditions of their being or well-being continue. Perhaps, however, M. Naudin does not mean that "evolutive force," or the force of vitality, is really homologous with common physical force, but only something which may be likened to it. In that case the parallel has only a metaphorical value, and the reason why variation must cease and species die out is still to seek. In short, if that which continues the series of individuals in propagation, whether like or unlike the parents, be a force in the physical sense of the term, then there is abundant provision in Nature for its indefinite replenishment. If, rather, it be a part or phase of that something which directs and determines the expenditure of force, then it is not subject to the laws of the latter, and there is no ground for inferring its exhaustibility. The limited vitality is an unproved and unprovable conjecture. The evolutive force, dying out in the using, is either the same conjecture repeated, or a misapplied analogy. After all--apart from speculative analogies--the only evidences we possess which indicate a tendency in species to die out, are those to which Mr. Darwin has called attention. These are, first, the observed deterioration which results, at least in animals, from continued breeding in and in, which may possibly be resolvable into cumulative heritable disease; and, secondly, as already stated (p. 285), what may be termed the sedulous and elaborate pains everywhere taken in Nature to prevent close breeding--arrangements which are particularly prominent in plants, the greater number of which bear hermaphrodite blossoms. The importance of this may be inferred from the universality, variety, and practical perfection of the arrangements which secure the end; and the inference may fairly be drawn that this is the physiological import of sexes. It follows from this that there is a tendency, seemingly inherent, in species as in individuals, to die out; but that this tendency is counteracted or checked by sexual wider breeding, which is, on the whole, amply secured in Nature, and which in some way or other reenforces vitality to such an extent as to warrant Darwin's inference that "some unknown great good is derived from the union of individuals which have been kept distinct for many generations." Whether this reenforcement is a complete preventive of decrepitude in species, or only a palliative, is more than we can determine. If the latter, then existing species and their derivatives must perish in time, and the earth may be growing poorer in species, as M. Naudin supposes, through mere senility. If the former, then the earth, if not even growing richer, may be expected to hold its own, and extant species or their derivatives should last as long as the physical world lasts and affords favorable conditions. General analogies seem to favor the former view. Such facts as we possess, and the Darwinian hypothesis, favor the latter. XIII EVOLUTIONARY TELEOLOGY When Cuvier spoke of the "combination of organs in such order that they may be in consistence with the part which the animal has to play in Nature," his opponent, Geoffroy St.-Hilaire, rejoined, "I know nothing of animals which have to play a part in Nature." The discussion was a notable one in its day. From that time to this, the reaction of morphology against "final causes" has not rarely gone to the extent of denying the need and the propriety of assuming ends in the study of animal and vegetable organizations. Especially in our day, when it became apparent that the actual use of an organ might not be the fundamental reason of its existence-- that one and the same organ, morphologically considered, was modified in different cases to the most diverse uses, while intrinsically different organs subserved identical functions, and consequently that use was a fallacious and homology the surer guide to correct classification--it was not surprising that teleological ideas nearly disappeared from natural history. Probably it is still generally thought that the school of Cuvier and that of St.-Hilaire have neither common ground nor capability of reconcilement. In a review of Darwin's volume on the "Fertilization of Orchids" * (too technical and too detailed for reproduction here), and later in a brief sketch of the character of his scientific work (art. IX, p. 234), we expressed our sense of the great gain to science from his having brought back teleology to natural history. In Darwinism, usefulness and purpose come to the front again as working principles of the first order; upon them, indeed, the whole system rests. To most, this restoration of teleology has come from an unexpected quarter, and in an unwonted guise; so that the first look of it is by no means reassuring to the minds of those who cherish theistic views of Nature. Adaptations irresistibly suggesting purpose had their supreme application in natural theology. Being manifold, particular, and exquisite, and evidently inwrought into the whole system of the organic world, they were held to furnish irrefragable as well as independent proof of a personal designer, a divine originator of Nature. By a confusion of thought, now obvious, but at the time not unnatural, they were also regarded as proof of a direct execution of the contriver's purpose in the creation of each organ and organism, as it were, in the manner man contrives and puts together a machine--an idea which has been set up as the orthodox doctrine, but which to St. Augustine and other learned Christian fathers would have savored of heterodoxy. In the doctrine of the origination of species through natural selection, these adaptations appear as the outcome rather than as the motive, as final results rather than final causes. Adaptation to use, although the very essence of Darwinism, is not a fixed and inflexible adaptation, realized once for all at the outset; it includes a long progression and succession of modifications, adjusting themselves to changing circumstances, under which they may be more and more diversified, specialized, and in a just sense perfected. Now, the question is, Does this involve the destruction or only the reconstruction of our consecrated ideas of teleology? Is it compatible with our seemingly inbore conception of Nature as an ordered system? Furthermore, and above all, can the Darwinian theory itself dispense with the idea of purpose, in the ordinary sense of the word, as tantamount to design? From two opposing sides we hear the first two questions answered in the negative. And an affirmative response to the third is directly implied in the following citation: "The word purpose has been used in a sense to which it is, perhaps, worth while to call attention. Adaptation of means to an end may be provided in two ways that we at present know of: by processes of natural selection, and by the agency of an intelligence in which an image or idea of the end preceded the use of the means. In both cases the existence of the adaptation is accounted for by the necessity or utility of the end. It seems to me convenient to use the word purpose as meaning generally the end to which certain means are adapted, both in these two cases and in any other that may hereafter become known, provided only that the adaptation is accounted for by the necessity or utility of the end. And there seems no objection to the use of the phrase 'final cause' in this wider sense, if it is to be kept at all. The word 'design' might then be kept for the special case of adaptation by an intelligence. And we may then say that, since the process of natural selection has been understood, purpose has ceased to suggest design to instructed people, except in cases where the agency of man is independently probable."--P.C.W., in the Contemporary Review for September, 1875, p. 657. The distinction made by this anonymous writer is convenient and useful, and his statement clear. We propose to adopt this use of the terms purpose and design, and to examine the allegation. The latter comes to this: "Processes of natural selection" exclude "the agency of an intelligence in which the image or idea of the end precedes the use of the means;" and since the former have been understood "purpose has ceased to suggest design to instructed people, except in cases where the agency of man is independently probable." The maxim "L'homme propose, Dieu dispose," under this reading means that the former has the monopoly of design, while the latter accomplishes without designing. Man's works alone suggest design. But it is clear to us that this monopoly is shared with certain beings of inferior grade. Granting that quite possibly the capture of flies for food by Dionaea and the sundews may be attributed to purpose apart from design (if it be practicable in the last resort to maintain this now convenient distinction), still their capture by a spider's-web, and by a swallow on the wing, can hardly "cease to suggest design to instructed people." And surely, in coming at his master's call, the dog fulfills his own design as well as that of his master; and so of other actions and constructions of brute animals. Without doubt so acute a writer has a clear and sensible meaning; so we conclude that he regards brutes as automata, and was thinking of design as coextensive merely with general conceptions. Not concerning ourselves with the difficulty he may have in drawing a line between the simpler judgments and affections of man and those of the highest-endowed brutes, we subserve our immediate ends by remarking that the automatic theory would seem to be one which can least of all dispense with design, since, either in the literal or current sense of the word, undesigned automatism is, as near as may be, a contradiction in terms. As the automaton man constructs manifests the designs of its maker and mover, so the more efficient automata which man did not construct would not legitimately suggest less than human intelligence. And so all adaptations in the animal and vegetable world which irresistibly suggest purpose (in the sense now accepted) would also suggest design, and, under the law of parsimony, claim to be thus interpreted, unless some other hypothesis will better account for the facts. We will consider, presently, if any other does so. We here claim only that some beings other than men design, and that the adaptations of means to ends in the structure of animals and plants, in so far as they carry the marks of purpose, carry also the implication of having been designed. Also, that the idea or hypothesis of a designing mind, as the author of Nature--however we came by it--having possession of the field, and being one which man, himself a designer, seemingly must needs form, cannot be rivaled except by some other equally adequate for explanation, or displaced except by showing the illegitimacy of the inference. As to the latter, is the common apprehension and sense of mankind in this regard well grounded? Can we rightly reason from our own intelligence and powers to a higher or a supreme intelligence ordering and shaping the system of Nature? A very able and ingenious writer upon "The Evidences of Design in Nature," in the Westminster Review for July, 1875, maintains the negative. His article may be taken as the argument in support of the position assumed by "P.C.W.," in the Contemporary Review above cited. It opens with the admission that the orthodox view is the most simple and apparently convincing, has had for centuries the unhesitating assent of an immense majority of thinkers, and that the latest master-writer upon the subject disposed to reject it, namely, Mill, comes to the conclusion that, "in the present state of our knowledge, the adaptations in Nature afford a large balance of probability in favor of creation by intelligence." It proceeds to attack not so much the evidence in favor of design as the foundation upon which the whole doctrine rests, and closes with the prediction that sooner or later the superstructure must fall. And, truly, if his reasonings are legitimate, and his conclusions just, "Science has laid the axe to the tree." "Given a set of marks which we look upon in human productions as unfailing indications of design," he asks, "is not the inference equally legitimate when we recognize these marks in Nature? To gaze on such a universe as this, to feel our hearts exult within us in the fullness of existence, and to offer in explanation of such beneficent provision no other word but Chance, seems as unthankful and iniquitous as it seems absurd. Chance produces nothing in the human sphere; nothing, at least, that can be relied upon for good. Design alone engenders harmony, consistency; and Chance not only never is the parent, but is constantly the enemy of these. How, then, can we suppose Chance to be the author of a system in which everything is as regular as clockwork? . . . The hypothesis of Chance is inadmissible." There is, then, in Nature, an order; and, in "P.C.W.'s" sense of the word, a manifest purpose. Some sort of conception as to the cause of it is inevitable, that of design first and foremost. "Why"--the Westminster Reviewer repeats the question--"why, if the marks of utility and adaptation are conclusive in the works of man, should they not be considered equally conclusive in the works of Nature?" His answer appears to us more ingenious than sound. Because, referring to Paley's watch,-- "The watch-finder is not guided solely in his inference by marks of adaptation and utility; he would recognize design in half a watch, in a mere fragment of a watch, just as surely as in a whole time-keeper . . . Two cog-wheels, grasping each other, will be thought conclusive evidence of design, quite independently of any use attaching to them. And the inference, indeed, is perfectly correct; only it is an inference, not from a mark of design, properly so called, but from a mark of human workmanship . . . No more is needed for the watch-finder, since all the works of man are, at the same time, products of design; but a great deal more is requisite for us, who are called upon by Paley to recognize design in works in which this stamp, this label of human workmanship, is wanting. The mental operation required in the one case is radically different from that performed in the other; there is no parallel, and Paley's demonstration is totally irrelevant."[XIII-2] But, surely, all human doings are not "products of design;" many are contingent or accidental. And why not suppose that the finder of the watch, or of the watch-wheel, infers both design and human workmanship? The two are mutually exclusive only on the supposition that man alone is a designer, which is simply begging the question in discussion. If the watch-finder's attention had been arrested by a different object, such as a spider's web, he would have inferred both design and non-human workmanship. Of some objects he might be uncertain whether they were of human origin or not, with-out ever doubting they were designed, while of others this might remain doubtful. Nor is man's recognition of human workmanship, or of any other, dependent upon his comprehending how it was done, or what particular ends it subserves. Such considerations make it clear that "the label of human workmanship" is not the generic stamp from which man infers design. It seems equally clear that "the mental operation required in the one case" is not so radically or materially "different from that performed in the other" as this writer would have us suppose. The judgment respecting a spider's web, or a trap-door spider's dwelling, would be the very same in this regard if it preceded, as it occasionally might, all knowledge of whether the object met with were of human or animal origin. A dam across a stream, and the appearance of the stumps of trees which entered into its formation, would suggest design quite irrespective of and antecedent to the considerable knowledge or experience which would enable the beholder to decide whether this was the work of men or of beavers. Why, then, should the judgment that any particular structure is a designed work be thought illegitimate when attributed to a higher instead of a lower intelligence than that of man? It might, indeed, be so if the supposed observer had no conception of a power and intelligence superior to his own. But it would then be more than "irrelevant;" it would be impossible, except on the supposition that the phenomena would of themselves give rise to such an inference. That it is now possible to make the inference, and, indeed, hardly possible not to make it, is sufficient warrant of its relevancy. It may, of course, be rejoined that, if this important factor is given, the inference yields no independent argument of a divine creator; and it may also be reasonably urged that the difference between things that are made under our observation and comprehension, and things that grow, but have originated beyond our comprehension, is too wide for a sure inference from the one to the other. But the present question involves neither of these. It is simply whether the argument for design from adaptations in Nature is relevant, not whether it is independent or sure. It is conceded that the argument is analogical, and the parallel incomplete. But the gist is in the points that are parallel or similar. Pulleys, valves, and suchlike elaborate mechanical adaptations, cannot differ greatly in meaning, wherever met with. The opposing argument is repeated and passed in another form: "The evidence of design afforded by the marks of adaptation in works of human competence is null and void in the case of creation itself . . . Nature is full of adaptations; but these are valueless to us as traces of design, unless we know something of the rival adaptations among which an intelligent being might have chosen. To assert that in Nature no such rival adaptations existed, and that in every case the useful function in question could be established by no other instrument but one, is simply to reason in a circle, since it is solely from what we find existing that our notions of possibility and impossibility are drawn. . . . We cannot imagine ourselves in the position of the Creator before his work began, nor examine the materials among which he had to choose, nor count the laws which limited his operations. Here all is dark, and the inference we draw from the seeming perfections of the existing instruments or means is a measure of nothing but our ignorance." But the question is not about the perfection of these adaptations, or whether others might have been instituted in their place. It is simply whether observed adaptations of intricate sorts, admirably subserving uses, do or do not legitimately suggest to one designing mind that they are the product of some other. If so, no amount of ignorance, or even inconceivability, of the conditions and mode of production could affect the validity of the inference, nor could it be affected by any misunderstanding on our part as to what the particular use or function was; a statement which would have been deemed superfluous, except for the following: "There is not an organ in our bodies but what has passed, and is still passing, through a series of different and often contradictory interpretations. Our lungs, for instance, were anciently conceived to be a kind of cooling apparatus, a refrigerator; at the close of the last century they were supposed to be a centre of combustion; and nowadays both these theories have been abandoned for a third . . . Have these changes modified in the slightest degree the supposed evidence of design?" We have not the least idea why they should. So, also, of complicated processes, such as human digestion, being replaced by other and simpler ones in lower animals, or even in certain plants. If "we argue the necessity of every adaptation solely from the fact that it exists," and that "we cannot mutilate it grossly without injury to the function," we do not "announce triumphantly that digestion is impossible in any way but this," etc., but see equal wisdom and no impugnment of design in any number of simpler adaptations accomplishing equivalent purposes in lower animals. Finally, adaptation and utility being the only marks of design in Nature which we possess, and adaptation only as subservient to usefulness, the Westminster Reviewer shows us how: "The argument from utility may be equally refuted another way. We found in our discussion of the mark of adaptation that the positive evidence of design afforded by the mechanisms of the human frame was never accompanied by the possibility of negative evidence. We regarded this as a suspicious circumstance, just as the fox, invited to attend the lion in his den, was deterred from his visit by observing that all the foottracks lay in one direction. The same suspicious circumstance warns us now. If positive evidence of design be afforded by the presence of a faculty, negative evidence of design ought to be afforded by the absence of a faculty. This, however, is not the case." [Then follows the account of a butterfly, which, from the wonderful power of the males to find the females at a great distance, is conceived to possess a sixth sense.] "Do we consider the deficiency of this sixth sense in man as the slightest evidence against design? Should we be less apt to infer creative wisdom if we had only four senses instead of five, or three instead of four? No, the case would stand precisely as it does now. We value our senses simply because we have them, and because our conception of life as we desire it is drawn from them. But to reason from such value to the origin of our endowment, to argue that our senses must have been given to us by a deity because we prize them, is evidently to move round and round in a vicious circle. "The same rejoinder is easily applicable to the argument from beauty, which indeed is only a particular aspect of the argument from utility. It is certainly improbable that a random daubing of colors on a canvas will produce a tolerable painting, even should the experiment be continued for thousands of years. Our conception of beauty being given, it is utterly improbable that chance should select, out of the infinity of combinations which form and color may afford, the precise combination which that conception will approve. But the universe is not posterior to our sense of beauty, but antecedent to it: our sense of beauty grows out of what we see; and hence the conformance of our world to our aesthetical conceptions is evidence, not of the world's origin, but of our own." We are accustomed to hear design doubted on account of certain failures of provision, waste of resources, or functionless condition of organs; but it is refreshingly new to have the very harmony itself of man with his surroundings, and the completeness of provision for his wants and desires, brought up as a refutation of the validity of the argument for design. It is hard, indeed, if man must be out of harmony with Nature in order to judge anything respecting it, or his relations with it; if he must have experience of chaos before he can predicate anything of order. But is it true that man has all that he conceives of, or thinks would be useful, and has no "negative evidence of design afforded by the absence of a faculty" to set against the positive evidence afforded by its presence? He notes that he lacks the faculty of flight, sometimes wants it, and in dreams imagines that he has it, yet as thoroughly believes that he was designed not to have it as that he was designed to have the faculties and organs which he possesses. He notes that some animals lack sight, and so, with this negative side of the testimony to the value of vision, he is "apt to infer creative wisdom" both in what he enjoys and in what the lower animal neither needs nor wants. That man does not miss that which he has no conception of, and is by this limitation disqualified from judging rightly of what he can conceive and know, is what the Westminster Reviewer comes to, as follows: "We value the constitution of our world because we live by it, and because we cannot conceive ourselves as living otherwise. Our conceptions of possibility, of law, of regularity, of logic, are all derived from the same source; and as we are constantly compelled to work with these conceptions, as in our increasing endeavors to better our condition and increase our provision we are constantly compelled to guide ourselves by Nature's regulations, we accustom ourselves to look upon these regularities and conceptions as antecedent to all work, even to a Creator's, and to judge of the origin of Nature as we judge of the origin of inventions and utilities ascribable to man. This explains why the argument of design has enjoyed such universal popularity. But that such popularity is no criterion of the argument's worth, and that, indeed, it is no evidence of anything save of an unhappy weakness in man's mental constitution, is abundantly proved by the explanation itself." Well, the constitution and condition of man being such that he always does infer design in Nature, what stronger presumption could there possibly be of the relevancy of the inference? We do not say of its correctness: that is another thing, and is not the present point. At the last, as has well been said, the whole question resolves itself into one respecting the ultimate veracity of Nature, or of the author of Nature, if there be any. Passing from these attempts to undermine the foundation of the doctrine--which we judge to be unsuccessful--we turn to the consideration of those aimed at the superstructure. Evidences of design may be relevant, but not cogent. They may, as Mill thought, preponderate, or the wavering balance may incline the other way. There are two lines of argument: one against the sufficiency, the other against the necessity, of the principle of design. Design has been denied on the ground that it squares with only one part of the facts, and fails to explain others; it may be superseded by showing that all the facts are in the way of being explained without it. The things which the principle of design does not explain are many and serious. Some are in their nature inexplicable, at least are beyond the power and province of science. Others are of matters which scientific students have to consider, and upon which they may form opinions, more or less well grounded. As to biological science--with which alone we are concerned--it is getting to be generally thought that this principle, as commonly understood, is weighted with much more than it can carry. This statement will not be thought exaggerated by those most familiar with the facts and the ideas of the age, and accustomed to look them in the face. Design is held to, no doubt, by most, and by a sure instinct; not, however, as always offering an explanation of the facts, but in spite of the failure to do so. The stumbling-blocks are various, and they lie in every path: we can allude only to one or two as specimens. Adaptation and utility are the marks of design. What, then, are organs not adapted to use marks of? Functionless organs of some sort are the heritage of almost every species. We have ways of seeming to account for them--and of late one which may really account for them--but they are unaccountable on the principle of design. Some, shutting their eyes to the difficulty, deny that we know them to be functionless, and prefer to believe they must have a use because they exist, and are more or less connected with organs which are correlated to obvious use; but only blindfolded persons care to tread the round of so narrow a circle. Of late some such abortive organs in flowers and fruits are found to have a use, though not the use of their kind. But unwavering believers in design should not trust too much to instances of this sort. There is an old adage that, if anything be kept long enough, a use will be found for it. If the following up of this line, when it comes in our way, should bring us round again to a teleological principle, it will not be one which conforms to the prevalent ideas now attacked. It is commonly said that abortive and useless organs exist for the sake of symmetry, or as parts of a plan. To say this, and stop there, is a fine instance of mere seeming to say something. For, under the principle of design, what is the sense of introducing useless parts into a useful organism, and what shadow of explanation does "symmetry" give? To go further and explain the cause of the symmetry and how abortive organs came to be, is more to the purpose, but it introduces quite another principle than that of design. The difficulty recurs in a somewhat different form when an organ is useful and of exquisite perfection in some species, but functionless in another. An organ, such as an eye, strikes us by its exquisite and, as we may, perfect adaptation and utility in some animal; it is found repeated, still useful but destitute of many of its adaptations, in some animal of lower grade; in some one lower still it is rudimentary and useless. It is asked, If the first was so created for its obvious and actual use, and the second for such use as it has, what was the design of the third? One more case, in which use after all is well subserved, we cite from the article already much quoted from: "It is well known that certain fishes (Pleuronecta) display the singularity of having both eyes on the same side of their head, one eye being placed a little higher than the other. This arrangement has its utility; for the Pleuronecta, swimming on their side quite near the bottom of the sea, have little occasion for their eyesight except to observe what is going on above them. But the detail to which we would call notice is, that the original position of the eyes is symmetrical in these fishes, and that it is only at a certain point of their development that the anomaly is manifested, one of the eyes passing to the other side of the head. It is almost inconceivable that an intelligent being should have selected such an arrangement; and that, intending the eyes to be used only on one side of the head, he should have placed them originally on different sides." Then the waste of being is enormous, far beyond the common apprehension. Seeds, eggs, and other germs, are designed to be plants and animals, but not one of a thousand or of a million achieves its destiny. Those that fall into fitting places and in fitting numbers find beneficent provision, and, if they were to wake to consciousness, might argue design from the adaptation of their surroundings to their well-being. But what of the vast majority that perish? As of the light of the sun, sent forth in all directions, only a minute portion is intercepted by the earth or other planets where some of it may be utilized for present or future life, so of potential organisms, or organisms begun, no larger proportion attain the presumed end of their creation. "Destruction, therefore, is the rule; life is the exception. We notice chiefly the exception--namely, the lucky prize-winner in the lottery-- and take but little thought about the losers, who vanish from our field of observation, and whose number it is often impossible to estimate. But, in this question of design, the losers are important witnesses. If the maxim 'audi alteram partem' is applicable anywhere, it is applicable here. We must hear both sides, and the testimony of the seed fallen on good ground must be corrected by the testimony of that which falls by the wayside, or on the rocks. When we find, as we have seen above, that the sowing is a scattering at random, and that, for one being provided for and living, ten thousand perish unprovided for, we must allow that the existing order would be accounted as the worst disorder in any human sphere of action." It is urged, moreover, that all this and much more applies equally to the past stages of our earth and its immensely long and varied succession of former inhabitants, different from, yet intimately connected with, the present. It is not one specific creation that the question has to deal with--as was thought not very many years ago--but a series of creations through countless ages, and of which the beginning is unknown. These references touch a few out of many points, and merely allude to some of the difficulties which the unheeding pass by, but which, when brought before the mind, are seen to be stupendous. Somewhat may be justly, or at least plausibly, said in reply to all this from the ordinary standpoint, but probably not to much effect. There were always insuperable difficulties, which, when they seemed to be few, might be regarded as exceptional; but, as they increase in number and variety, they seem to fall into a system. No doubt we may still insist that, "in the present state of our knowledge, the adaptations in Nature afford a large balance of probability in favor of creation by intelligence," as Mill concluded; and probability must needs be the guide of reason through these dark places. Still, the balancing of irreconcilable facts is not a satisfying occupation, nor a wholly hopeful one, while fresh weights are from time to time dropping into the lighter side of the balance. Strong as our convictions are, they may be overborne by evidence. We cannot rival the fabled woman of Ephesus, who, beginning by carrying her calf from the day of its birth, was still able to do so when it became an ox. The burden which our fathers carried comfortably, with some adventitious help, has become too heavy for our shoulders. Seriously, there must be something wrong in the position, some baleful error mixed with the truth, to which this contradiction of our inmost convictions may be attributed. The error, as we suppose, lies in the combination of the principle of design with the hypothesis of the immutability and isolated creation of species. The latter hypothesis, in its nature un-provable, has, on scientific grounds, become so far improbable that few, even of the anti-Darwinian naturalists, now hold to it; and, whatever may once have been its religious claims, it is at present a hinderance rather than a help to any just and consistent teleology. By the adoption of the Darwinian hypothesis, or something like it, which we incline to favor, many of the difficulties are obviated, and others diminished. In the comprehensive and far-reaching teleology which may take the place of the former narrow conceptions, organs and even faculties, useless to the individual, find their explanation and reason of being. Either they have done service in the past, or they may do service in the future. They may have been essentially useful in one way in a past species, and, though now functionless, they may be turned to useful account in some very different way hereafter. In botany several cases come to our mind which suggest such interpretation. Under this view, moreover, waste of life and material in organic Nature ceases to be utterly inexplicable, because it ceases to be objectless. It is seen to be a part of the general "economy of Nature," a phrase which has a real meaning. One good illustration of it is furnished by the pollen of flowers. The seeming waste of this in a pine-forest is enormous. It gives rise to the so-called "showers of sulphur," which every one has heard of. Myriads upon myriads of pollen-grains (each an elaborate organic structure) are wastefully dispersed by the winds to one which reaches a female flower and fertilizes a seed. Contrast this with one of the close-fertilized flowers of a violet, in which there are not many times more grains of pollen produced than there are of seeds to be fertilized; or with an orchis-flower, in which the proportion is not widely different. These latter are certainly the more economical; but there is reason to believe that the former arrangement is not wasteful. The plan in the violet-flower assures the result with the greatest possible saving of material and action; but this result, being close-fertilization or breeding in and in, would, without much doubt, in the course of time, defeat the very object of having seeds at all.[XIII-3] So the same plant produces other flowers also, provided with a large surplus of pollen, and endowed (as the others are not) with color, fragrance, and nectar, attractive to certain insects, which are thereby induced to convey this pollen from blossom to blossom, that it may fulfill its office. In such blossoms, and in the great majority of flowers, the fertilization and consequent perpetuity of which are committed to insects, the likelihood that much pollen may be left behind or lost in the transit is sufficient reason for the apparent superfluity. So, too, the greater economy in orchis-flowers is accounted for by the fact that the pollen is packed in coherent masses, all attached to a common stalk, the end of which is expanded into a sort of button, with a glutinous adhesive face (like a bit of sticking-plaster), and this is placed exactly where the head of a moth or butterfly will be pressed against it when it sucks nectar from the flower, and so the pollen will be bodily conveyed from blossom to blossom, with small chance of waste or loss. The floral world is full of such contrivances; and while they exist the doctrine of purpose or final cause is not likely to die out. Now, in the contrasted case, that of pine-trees, the vast superabundance of pollen would be sheer waste if the intention was to fertilize the seeds of the same tree, or if there were any provision for insect-carriage; but with wide-breeding as the end, and the wind which "bloweth where it listeth" as the means, no one is entitled to declare that pine-pollen is in wasteful excess. The cheapness of wind-carriage may be set against the overproduction of pollen. Similar considerations may apply to the mould-fungi and other very low organisms, with spores dispersed through the air in countless myriads, but of which only an infinitesimal portion find opportunity for development. The myriads perish. The exceptional one, falling into a fit medium, is imagined by the Westminster Reviewer to argue design from the beneficial provision it finds itself enjoying, in happy ignorance of the perishing or latent multitude. But, in view of the large and important part they play (as the producers of all fermentation and as the omnipresent scavenger-police of Nature), no good ground appears for arguing either wasteful excess or absence of design from the vast disparity between their potential and their actual numbers. The reserve and the active members of the force should both be counted in, ready as they always and everywhere are for service. Considering their ubiquity, persistent vitality, and promptitude of action upon fitting occasion, the suggestion would rather be that, while ". . . thousands at His bidding speed, And post o'er land and ocean without rest, They also serve [which] only stand and wait." Finally, Darwinian teleology has the special advantage of accounting for the imperfections and failures as well as for successes. It not only accounts for them, but turns them to practical account. It explains the seeming waste as being part and parcel of a great economical process. Without the competing multitude, no struggle for life; and without this, no natural selection and survival of the fittest, no continuous adaptation to changing surroundings, no diversification and improvement, leading from lower up to higher and nobler forms. So the most puzzling things of all to the old-school teleologists are the principia of the Darwinian. In this system the forms and species, in all their variety, are not mere ends in themselves, but the whole a series of means and ends, in the contemplation of which we may obtain higher and more comprehensive, and perhaps worthier, as well as more consistent, views of design in Nature than heretofore. At least, it would appear that in Darwinian evolution we may have a theory that accords with if it does not explain the principal facts, and a teleology that is free from the common objections. But is it a teleology, or rather--to use the new-fangled term--a dysteleology? That depends upon how it is held. Darwinian evolution (whatever may be said of other kinds) is neither theistical nor nontheistical. Its relations to the question of design belong to the natural theologian, or, in the larger sense, to the philosopher. So long as the world lasts it will probably be open to any one to hold consistently, in the last resort, either of the two hypotheses, that of a divine mind, or that of no divine mind. There is no way that we know of C by which the alternative may be excluded. Viewed philosophically, the question only is, Which is the better supported hypothesis of the two? We have only to say that the Darwinian system, as we understand it, coincides well with the theistic view of Nature. It not only acknowledges purpose (in the Contemporary Reviewer's sense), but builds upon it; and if purpose in this sense does not of itself imply design, it is certainly compatible with it, and suggestive of it. Difficult as it may be to conceive and impossible to demonstrate design in a whole of which the series of parts appear to be contingent, the alternative may be yet more difficult and less satisfactory. If all Nature is of a piece--as modern physical philosophy insists-- then it seems clear that design must in some way, and in some sense, pervade the system, or be wholly absent from it. Of the alternatives, the predication of design--special, general, or universal, as the case may be--is most natural to the mind; while the exclusion of it throughout, because some utilities may happen, many adaptations may be contingent results, and no organic maladaptations could continue, runs counter to such analogies as we have to guide us, and leads to a conclusion which few men ever rested in. It need not much trouble us that we are incapable of drawing clear lines of demarkation between mere utilities, contingent adaptations, and designed contrivances in Nature; for we are in much the same condition as respects human affairs and those of lower animals. What results are comprehended in a plan, and what are incidental, is often more than we can readily determine in matters open to observation. And in plans executed mediately or indirectly, and for ends comprehensive and far-reaching, many purposed steps must appear to us incidental or meaningless. But the higher the intelligence, the more fully will the incidents enter into the plan, and the more universal and interconnected may the ends be. Trite as the remark is, it would seem still needful to insist that the failure of a finite being to compass the designs of an infinite mind should not invalidate its conclusions respecting proximate ends which he can understand. It is just as in physical science, where, as our knowledge and grasp increase, and happy discoveries are made, wider generalizations are formed, which commonly comprehend, rather than destroy, the earlier and partial ones. So, too, the "sterility" of the old doctrine of final causes in science, and the presumptuous uses made of them, when it was supposed that every adapted arrangement or structure existed for this or that direct and special end, and for no other, can hardly be pressed to the conclusion that there are no final causes, i.e., ultimate reasons of things.[XIII-4] Design in Nature is distinguished from that in human affairs--as it fittingly should be--by all comprehensiveness and system. Its theological synonym is Providence. Its application in particular is surrounded by similar insoluble difficulties; nevertheless, both are bound up with theism. Probably few at the present day will maintain that Darwinian evolution is incompatible with the principle of design; but some insist that the theory can dispense with, and in fact supersedes, this principle. The Westminster Reviewer cleverly expounds how it does so. The exposition is too long to quote, and an abstract is unnecessary, for the argument adverse to design is, as usual, a mere summation or illustration of the facts and assumptions of the hypothesis itself, by us freely admitted. Simplest forms began; variations occurred among them; under the competition consequent upon the arithmetical or geometrical progression in numbers, only the fittest for the conditions survive and propagate, vary further, and are similarly selected; and so on. "Progress having once begun by the establishment of species, the laws of atavism and variability will suffice to tell the remainder of the story. The colonies gifted with the faculty of forming others in their likeness will soon by their increase become sole masters of the field; but the common enemy being thus destroyed, the struggle for life will be renewed among the conquerors. The saying that 'a house divided against itself cannot stand,' receives in Nature its flattest contradiction. Civil war is here the very instrument of progress; it brings about the survival of the fittest. Original differences in the cell-colonies, however slight, will bring about differences of life and action; the latter, continued through successive generations, will widen the original differences of structure; innumerable species will thus spring up, branching forth in every direction from the original stock; and the competition of these species among each other for the ground they occupy, or the food they seek, will bring out and develop the powers of the rivals. One chief cause of superiority will lie in the division of labor instituted by each colony; or, in other words, in the localization of the colony's functions. In the primitive associations (as in the lowest organisms existing now), each cell performed much the same work as its neighbor, and the functions necessary to the existence of the whole (alimentation, digestion, respiration, etc.) were exercised by every colonist in his own behalf. Social life, however, acting upon the cells as it acts upon the members of a human family, soon created differences among them--differences ever deepened by continuance, and which, by narrowing the limits of each colonist's activity, and increasing his dependence on the rest, rendered him fitter for his special task. Each function was thus gradually monopolized; but it came to be the appanage of a single group of cells, or organ; and so excellent did this arrangement prove, so greatly were the powers of each commonwealth enhanced by the division of its labor, that the more organs a colony possessed, the more likely it was to succeed in its struggle for life. . . We shall go no further, for the reader will easily fill out the remainder of the picture for himself. Man is but an immense colony of cells, in which the division of labor, together with the centralization of the nervous system, has reached its highest limit. It is chiefly to this that his superiority is due; a superiority so great, as regards certain functions of the brain, that he may be excused for having denied his humbler relatives, and dreamed that, standing alone in the centre of the universe, sun, moon, and stars, were made for him." Let us learn from the same writer how both eyes of the flounder get, quite unintentionally, on the same side of the head. The writer makes much of this case (see p. 306), and we are not disposed to pass it by: "A similar application may be made to the Pleuronecta. Presumably, these fishes had adopted their peculiar mode of swimming long before the position of their eyes became adapted to it. A spontaneous variation occurred, consisting in the passage of one eye to the opposite side of the head; and this variation afforded its possessors such increased facilities of sight that in the course of time the exception became the rule. But the remarkable point is, that the law of heredity not only preserved the variation itself, but the date of its occurrence; and that, although for thousands of years the adult Pleuronecta have had both eyes on the same side, the young still continue during their earlier development to exhibit the contrary arrangement, just as if the variation still occurred spontaneously." Here a wonderful and one would say unaccountable transference takes place in a short time. As Steenstrup showed, one eye actually passes through the head while the young fish is growing. We ask how this comes about; and we are told, truly enough, that it takes place in each generation because it did so in the parents and in the whole line of ancestors. Why offspring should be like parent is more than any one can explain; but so it is, in a manner so nearly fixed and settled that we can count on it; yet not from any absolute necessity that we know of, and, indeed, with sufficiently striking difference now and then to demonstrate that it might have been otherwise, or is so in a notable degree. This transference of one eye through the head, from the side where it would be nearly useless to that in which it may help the other, bears all the marks of purpose, and so carries the implication of design. The case is adduced as part of the evidence that Darwinian evolution supersedes design. But how? Not certainly in the way this goes on from generation to generation; therefore, doubtless in the way it began. So we look for the explanation of how it came about at the first unintentionally or accidentally; how, under known or supposed conditions, it must have happened, or at least was likely to happen. And we read, "A spontaneous variation occurred, consisting in the passage of one eye to the opposite side of the head." That is all; and we suppose there is nothing more to be said. In short, this surprising thing was undesigned because it took place, and has taken place ever since! The writer presumes, moreover (but this is an obiter dictum), that the peculiarity originated long after flounders had fixed the habit of swimming on one side (and in this particular case it is rather difficult to see how the two may have gone on pari passu), and so he cuts away all obvious occasion for the alteration through the summation of slight variations in one direction, each bringing some advantage. This is a strongly-marked case; but its features, although unusually prominent, are like those of the general run of the considerations by which evolution is supposed to exclude design. Those of the penultimate citation and its context are all of the same stamp. The differences which begin as variations are said to be spontaneous--a metaphorical word of wide meanings--are inferred to be casual (whereas we only know them to be occult), or to be originated by surrounding agencies (which is not in a just sense true); they are legitimately inferred to be led on by natural selection, wholly new structures or organs appear, no one can say how, certainly no one can show that they are necessary outcomes of what preceded; and these two are through natural selection kept in harmony with the surroundings, adapted to different ones, diversified, and perfected; purposes are all along subserved through exquisite adaptations; and yet the whole is thought to be undesigned, not because of any assigned reason why this or that must have been thus or so, but simply because they all occurred in Nature! The Darwinian theory implies that the birth and development of a species are as natural as those of an individual, are facts of the same kind in a higher order. The alleged proof of the absence of design from it amounts to a simple reiteration of the statement, with particulars. Now, the marks of contrivance in the structure of animals used not to be questioned because of their coming in the way of birth and development. It is curious that a further extension of this birth and development should be held to disprove them. It appears to us that all this is begging the question against design in Nature, instead of proving that it may be dispensed with. Two things have helped on this confusion. One is the notion of the direct and independent creation of species, with only an ideal connection between them, to question which was thought to question the principle of design. The other is a wrong idea of the nature and province of natural selection. In former papers we have over and over explained the Darwinian doctrine in this respect. It may be briefly illustrated thus: Natural selection is not the wind which propels the vessel, but the rudder which, by friction, now on this side and now on that, shapes the course. The rudder acts while the vessel is in motion, effects nothing when it is at rest. Variation answers to the wind: "Thou hearest the sound thereof, but canst not tell when it cometh and whither it goeth." Its course is controlled by natural selection, the action of which, at any given moment, is seemingly small or insensible; but the ultimate results are great. This proceeds mainly through outward influences. But we are more and more convinced that variation, and therefore the ground of adaptation, is not a product of, but a response to, the action of the environment. Variations, in other words, the differences between individual plants and animals, however originated, are evidently not from without but from within--not physical but physiological. We cannot here assign particularly the reasons for this opinion. But we notice that the way in which varieties make their appearance strongly suggests it. The variations of plants which spring up in a seed-bed, for instance, seem to be in no assignable relation to the external conditions. They arise, as we say, spontaneously, and either with decided characters from the first, or with obvious tendencies in one or few directions. The occult power, whatever it be, does not seem in any given case to act vaguely, producing all sorts of variations from a common centre, to be reduced by the struggle for life to fewness and the appearance of order; there are, rather, orderly indications from the first. The variations of which we speak, as originating in no obvious casual relation to the external conditions, do not include dwarfed or starved, and gigantesque or luxuriant forms, and those drawn up or expanded on the one hand, or contracted and hardened on the other, by the direct difference in the supply of food and moisture, light and heat. Here the action of the environment is both obvious and direct. But such cases do not account for much in evolution. Moreover, while we see how the mere struggle and interplay among occurring forms may improve them and lead them on, we cannot well imagine how the adaptations which arrest our attention are thereby secured. Our difficulty, let it be understood, is not about the natural origination of organs. To the triumphant outcry, "How can an organ, such as an eye, be formed under Nature?" we would respond with a parallel question, How can a complex and elaborate organ, such as a nettle-sting, be formed under Nature? But it is so formed. In the same species some individuals have these exquisitely-constructed organs and some have not. And so of other glands, the structure and adaptation of which, when looked into, appear to be as wonderful as anything in Nature. The impossibility lies in conceiving how the obvious purpose was effectuated under natural selection alone. This, under our view, any amount of gradation in a series of forms goes a small way in explaining. The transit of a young flounder's eye across the head is a capital instance of a wonderful thing done under Nature, and done unaccountably. But simpler correlations are involved in similar difficulty. The superabundance of the pollen of pine-trees above referred to, and in oak-trees, is correlated with chance fertilization under the winds. In the analogous instance of willows a diminished amount of pollen is correlated with direct transportation by insects. Even in so simple a case as this it is not easy to see how this difference in the conveyance would reduce the quantity of pollen produced. It is, we know, in the very alphabet of Darwinism that if a male willow-tree should produce a smaller amount of pollen, and if this pollen communicated to the offspring of the female flowers it fertilized a similar tendency (as it might), this male progeny would secure whatever advantage might come from the saving of a certain amount of work and material; but why should it begin to produce less pollen? But this is as nothing compared with the arrangements in orchid-flowers, where new and peculiar structures are introduced--structures which, once originated and then set into variation, may thereupon be selected, and thereby led on to improvement and diversification. But the origination, and even the variation, still remains unexplained either by the action of insects or by any of the processes which collectively are personified by the term natural selection. We really believe that these exquisite adaptations have come to pass in the course of Nature, and under natural selection, but not that natural selection alone explains or in a just sense originates them. Or rather, if this term is to stand for sufficient cause and rational explanation, it must denote or include that inscrutable something which produces--as well as that which results in the survival of--"the fittest." We have been considering this class of questions only as a naturalist might who sought for the proper or reasonable interpretation of the problem before him, unmingled with considerations from any other source. Weightier arguments in the last resort, drawn from the intellectual and moral constitution of man, lie on a higher plane, to which it was unnecessary for our particular purpose to rise, however indispensable this be to a full presentation of the evidence of mind in Nature. To us the evidence, judged as impartially as we are capable of judging, appears convincing. But, whatever view one unconvinced may take, it cannot remain doubtful what position a theist ought to occupy. If he cannot recognize design in Nature because of evolution, he may be ranked with those of whom it was said, "Except ye see signs and wonders ye will not believe." How strange that a convinced theist should be so prone to associate design only with miracle! All turns, however, upon what is meant by this Nature, to which it appears more and more probable that the being and becoming--no less than the well-being and succession--of species and genera, as well as of individuals, are committed. To us it means "the world of force and movement in time and space," as Aristotle defined it--the system and totality of things in the visible universe. What is generally called Nature Prof. Tyndall names matter--a peculiar nomenclature, requiring new definitions (as he avers), inviting misunderstanding, and leaving the questions we are concerned with just where they were. For it is still to ask: whence this rich endowment of matter? Whence comes that of which all we see and know is the outcome? That to which potency may in the last resort be ascribed, Prof. Tyndall, suspending further judgment, calls mystery--using the word in one of its senses, namely, something hidden from us which we are not to seek to know. But there are also mysteries proper to be inquired into and to be reasoned about; and, although it may not be given unto us to know the mystery of causation, there can hardly be a more legitimate subject of philosophical inquiry. Most scientific men have thought themselves intellectually authorized to have an opinion about it. "For, by the primitive and very ancient men, it has been handed down in the form of myths, and thus left to later generations, that the Divine it is which holds together all Nature;" and this tradition, of which Aristotle, both naturalist and philosopher, thus nobly speaks[XIII-5]--continued through succeeding ages, and illuminated by the Light which has come into the world--may still express the worthiest thoughts of the modern scientific investigator and reasoner. FOOTNOTES: I-1. "On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life," by Charles Darwin, M.A., Fellow of the Royal, Geological, Linnaean, etc., Societies, Author of "Journal of Researches during H. M. S. Beagle's Voyage round the World." London: John Murray. 1859. 502 pp., post 8vo. I-2. Article in this Journal, vol. xxiv., p. 305. I-3. "Species tot sunt, quot diversas formas ab initio produxit Infinitum Ens; quae formae secundum generationis inditas leges, produxere plures, at sibi semper similes."--Linn. Phil. Bot., 99, 157. I-4. Agassiz, "Essay on Classification; Contributions to Natural History," p. 132, et seq. I-5. As to this, Darwin remarks that he can only hope to see the law hereafter proved true (p. 449); and p. 338: "Agassiz insists that ancient animals resemble to a certain extent the embryos of recent animals of the same classes; or that the geological succession of extinct forms is in some degree parallel to the embryological development of recent forms. I must follow Pictet and Huxley in thinking that the truth of this doctrine is very far from proved. Yet I fully expect to see it hereafter confirmed, at least in regard to subordinate groups, which have branched off from each other within comparatively recent times. For this doctrine of Agassiz accords well with the theory of natural selection." I-6. Op. cit., p. 131.--One or two Bridgewater Treatises, and most modern works upon natural theology, should have rendered the evidences of thought in inorganic Nature not "unexpected." I-7. Volume xvii. (2), 1854, p. 13. I-8. We suspect that this is not an ultimate fact, but a natural consequence of inheritance--the inheritance of disease or of tendency to disease, which close interbreeding perpetuates and accumulates, but wide breeding may neutralize or eliminate. I-9. The rules and processes of breeders of animals, and their results, are so familiar that they need not be particularized. Less is popularly known about the production of vegetable races. We refer our readers back to this Journal, vol. xxvii., pp. 440--442 (May, 1859), for an abstract of the papers of M. Vilmorin upon this subject. I-10. Quadrupeds of America," vol. ii., p. 239. I-11. "Proceedings of the American Academy of Arts and Sciences," vol. iv., p. 178. I-12. Owen adds a third, viz., vegetative repetition; but this, in the vegetable kingdom, is simply unity of type. I-13. "Contributions to Natural History of America," vol. i., pp. 127--131. I-14. Op. cit., p. 130. II-1. To parry an adversary's thrust at a vulnerable part, or to show that it need not be fatal, is an incomplete defense. If the discussion had gone on, it might, perhaps, have been made to appear that the Darwinian hypothesis, so far from involving the idea of necessity (except in the sense that everything is of necessity), was based upon the opposite idea, that of contingency. III-1. Vide "Proceedings of the British Association for the Advancement of Science," 1859, and London Athenoeum, passim. It appears to be conceded that these "celts" or stone knives are artificial productions, and apparently of the age of the mammoth, the fossil rhinoceros, etc. III-2. See "Correspondence of M. Nickles," in American Journal of Science and Arts, for March, 1860. III-3. See Morlot, "Some General Views on Archaeology," in American Journal of Science and Arts, for January, 186o, translated from "Bulletin de la Societe Vaudoise," 1859. III-4. Page 484, English edition. In the new American edition (vide Supplement, pp. 431, 432) the principal analogies which suggest the extreme view are referred to, and the remark is appended: "But this inference is chiefly grounded on analogy, and it is immaterial whether or not it be accepted. The case is different with the members of each great class, as the Vertebrata or Articulata; for here we have in the laws of homology, embryology, etc., some distinct evidence that all have descended from a single primordial parent." III-5. In Bibliotheque Universelle de Geneve, March, 1860. III-6. This we learn from his very interesting article, "De la Question de l'Homme Fossile," in the same (March) number of the Biblioteque Universelle. (See, also, the same author's "Note sur la Periode Quaternaire ou Diluvienne, consideree dans ses Rapports avec l'Epoque Actuelle," in the number for August, 1860, of the same periodical.) III-7. In Comptes Rendus, Academie des Sciences, February 2, 1857. III-8. Whatever it may be, it is not "the homoeopathic form of the transmutative hypothesis," as Darwin's is said to be (p. 252, American reprint), so happily that the prescription is repeated in the second (p. 259) and third (p. 271) dilutions, no doubt, on Hahnemann's famous principle, of an increase of potency at each dilution. Probably the supposed transmutation is per saltus. "Homoeopathic doses of transmutation," indeed! Well, if we really must swallow transmutation in some form or other, as this reviewer intimates, we might prefer the mild homoeopathic doses of Darwin's formula to the allopathic bolus which the Edinburgh general practitioner appears to be compounding. III-9. Vide North American Review, for April, 1860, p. 475, and Christian Examiner, for May, p. 457. III-10. Page 188, English edition. III-11. In American Journal of Science, July, 1860, pp. 147--149. III-12. In "Contributions to the Natural History of the United States," vol. i., p.128, 129. III-13. Contributions to the Natural History of the United States," vol. 1, p. 130; and American Journal of Science, July, 1860, p. 143. III-14. North American Review for April 1860, p. 506. III-15. Vide motto from Butler, prefixed to the second edition of Darwin's work. III-16. North American Review, loc. cit., p. 504. III-17. North American Review, loc. cit., p. 487, et passim. III-18. In American Journal of Science, July, 1860, p. 143. III-19. Vide article by Mr. C. Wright, in the Mathematical Monthly for May last. III-20. Vide Edinburgh Review for January, 1860, article on "Acclimatization," etc. III-21. American Journal of Science, July, 1860, p. 146. IV-1. A name which, at the close of his article, De Candolle proposes for the study of the succession of organized beings, to comprehend, therefore, palaeontology and all included under what is called geographical botany and zoology--the whole forming a science parallel to geology--the latter devoted to the history of unorganized bodies, the former, to that of organized beings, as respects origin, distribution, and succession. We are not satisfied with the word, notwithstanding the precedent of palaeontology; since ontology, the Science of being, has an established meaning as referring to mental existence--i.e., is a synonym for a department of metaphysics. IV-2. Natural History Review, January, 1862 IV-3. What the Rev. Principal Tulloch remarks in respect to the philosophy of miracles has a pertinent application here. We quote at second hand: "The stoutest advocates of interference can mean nothing more than that the Supreme Will has so moved the hidden springs of Nature that a new issue arises on given circumstances. The ordinary issue is supplanted by a higher issue. The essential facts before us are a certain set of phenomena, and a Higher Will moving them. How moving them? is a question for human definition; the answer to which does not and cannot affect the divine meaning of the change. Yet when we reflect that this Higher Will is every. where reason and wisdom, it seems a juster as well as a more comprehensive view to regard it as operating by subordination and evolution, rather than by interference or violation." IV-4. Particularly citing Flourens: "La ressemblance n'est qu'une condition secondaire; la condition essentielle est la descendance: ce n'est pas la ressemblance, c'est la succession des individus, qui fait l'espece." V-1. The phrase "Atlantic United States" is here used throughout in contradistinction to Pacific United States: to the former of course belong, botanically and geographically, the valley of the Mississippi and its tributaries up to the eastern border of the great woodless plains, which constitute an intermediate region. V-2. The tabulated list referred to was printed as an appendix to the official edition of this discourse, but is here omitted. V-3. American Journal of Science, 1867, p. 402; "Proceedings of American Academy," vol. viii., p. 244. V-4. "Memoirs of American Academy," vol. vi., pp. 377--458 (1859) V-5. Die vegetation der erde nach ihrer kilmatischen Anordnung," 1871. V-6. Reference should also be made to the extensive researches of Newberry upon the tertiary and cretaceous floras of the Western United States. See especially Prof. Newberry's paper in the Boston Journal of Natural History, vol. vii., No. 4, describing fossil plants of Vancouver's Island, etc.; his "Notes on the Later Extinct Floras of North America," etc., in "Annals of the Lyceum of Natural History," vol. ix., April, 1868; "Report on the Cretaceous and Tertiary Plants collected in Raynolds and Hayden's Yellowstone and Missouri Exploring Expedition, 1859--1860," published in 1869; and an interesting article entitled "The Ancient Lakes of Western America, their Deposits and Drainage," published in The American Naturalist, January, 1871. The only document I was able to consult was Lesquereux's "Report on the Fossil Plants," in Hayden's report of 1872. V-7. There is, at least, one instance so opportune to the present argument that it should not pass unnoticed, although I had overlooked the record until now. Onoclea sensibilis is a fern peculiar to the Atlantic United States (where it is common and wide-spread) and to Japan. Prof. Newberry identified it several years ago in a collection, obtained by Dr. Hayden, of miocene fossil plants of Dakota Territory, which is far beyond its present habitat. He moreover regards it as probably identical with a fossil specimen "described by the late Prof. E. Forbes, under the name of Filicites Hebridicus, and obtained by the Duke of Argyll from the island of Mull." V-8. "Darwinism in Morals," in Theological Review, April, 1871. VI-1. "Histoire des Sciences et des Sevants depuis deux Siecles, suivie d'autres etudes sur des sujets scientifiques, en particulier sur la Selection dans 1'Espèce Humaine, par Alphonse De Candolle." Geneve: H. Georg. 1873. "Addresses of George Bentham, President, read at the anniversary meetings of the Linnaean Society, 1862--1873." "Notes on the Classification, History, and Geographical Distribution of Compositae. By George Bentham." Separate issue from the Journal of the Linnean Society. Vol. XIII. London. 1873. "On Palaeontological Evidence of Gradual Modification of Animal Forms, read at the Royal Institution of Great Britain, April 25, 1873. By Prof. W.H. Flower." (Journal of the Royal Institution, pp. 11.) "The Distribution and Migration of Birds. Memoir presented to the National Academy of Sciences, January, 1865, abstracted in the American Journal of Science and the Arts. 1866, etc. By Spencer F. Baird." "The Story of the Earth and Man. By J.W. Dawson, LL.D., F.R.S., F.G.S., Principal and Vice-Chancellor of McGill University, Montreal. London: Hodder & Stoughton; New York: Harper & Brothers. 1873. Pp. 403, 12mo. VI-2. Since this article was in type, noteworthy examples of appreciative scientific judgment of the derivative hypothesis have come to hand: 1. In the opening address to the Geological Section of the British Association, at its recent meeting, by its president, the veteran Phillips, perhaps the oldest surviving geologist after Lyell; and, 2. That of Prof. Allman, President of the Biological Section. The first touches the subject briefly, but in the way of favorable suggestion; the second is a full and discriminating exposition of the reasons which seem to assure at least the provisional acceptance of the hypothesis, as a guide in all biological studies, "a key to the order and hidden forces of the world of life." VII-1. "The Theory of Evolution of Living Things, and the Application of the Principles of Evolution to Religion, considered as illustrative of the 'Wisdom and Beneficence of the Almighty.' By the Rev. George Henslow, M.A., F.L.S., F.G.S., etc." New York: Macmillan & Co. 1873. 12mo, pp. 220. "Systematic Theology. By Charles Hodge, D.D., Professor in the Theological Seminary, Princeton, New Jersey. Vol. ii. (Part II, Anthropology.") New York: Charles Scribner & Co. 1872. "Religion and Science: A Series of Sunday Lectures on the Relation of Natural and Revealed Religion, or the Truths Revealed in Nature and Scripture. By Joseph Le Conte, Professor of Geology and Natural History in the University of California." New York: D. Appleton & Co. 1874. 12mo, pp. 324. VII-2. "But with regard to the material world, we can at least go so far as this-- we can perceive that events are brought about, not by insulated interpositions of divine power, exerted in each particular case, but by the establishment of general laws.--Whewell's Bridgewater Treatise. "The only distinct meaning of the world 'natural' is stated, fixed, or settled; since what is natural as much requires and presupposes an intelligent agent to render it so--i.e., to effect it continually or at stated times--as what is supernatural or miraculous does to effect it for once."--Butler's Analogy. VIII-1. "What Is Darwinism? By Charles Hodge, Princeton, N.J." New York: Scribner, Armstrong & Co. 1874. "The Doctrine of Evolution. By Alexander Winchell, LL.D., etc. New York: Harper & Brothers. 1874. "Darwinism and Design; or, Creation by Evolution. By George St. Clair." London: Hodder & Stoughton. 1873. "Westminster Sermons. By the Rev. Charles Kingsley, F.L.S., F.G.S., Canon of Westminster, etc." London and New York: Macmillan & Co. 1874. VIII-2. These two postulate-mottoes are quoted in full in a previous article, in No. 446 of The Nation. XI-1. "Insectivorous Plants. By Charles Darwin, M.A., F.R.S." With Illustrations. London: John Murray. 1875. Pp. 462. New York: D. Appleton & Co. "The Movements and Habits of Climbing Plants. By Charles Darwin, M.A., F.R.S., etc." Second Edition, revised, with Illustrations. London: John Murray. 1875. Pp. 208. New York: D. Appleton & Co. XI-2. The Nation, Nos. 457, 458, 1874. It was in these somewhat light and desultory, but substantially serious, articles that some account of Mr. Darwin's observations upon the digestive powers of Drosera and Dionaea first appeared; in fact, their leading motive was to make sufficient reference to his then unpublished discoveries to guard against expected or possible claims to priority. Dr. Burdon-Sanderson's lecture, and the report in Nature, which first made them known in England, appeared later. A mistake on our part in the reading of a somewhat ambiguous sentence in a letter led to the remark, at the close of the first of those articles, that the leaf-trap of Dionaea had been paralyzed on one side in consequence of a dexterous puncture. What was communicated really related to Drosera. XI-3. A. Gray, in "Proceedings of the American Academy of Arts and Sciences," vol. iv., p. 98; and American Journal of Science and the Arts, March, 1859, p. 278. XII-1. "Les Especes affines et la Theorie de l'Evolution," par Charles Naudin, Membre de l'Institut, in Bulletin de la Societe Botanique de France, tome xxi., pp. 240-272, 1874. See also Comptes Rendus, September 27 and October 4, 1875, reproduced in "Annales des Sciences Naturelles," 1876, pp. 73-81. XII-2. In noticing M. Naudin's paper in the Comptes Rendus, now reprinted in the "Annales des Sciences Naturelles," entitled "Variation desordonnee des Plantes Hybrides et Deductions qu'on peut en tirer," we were at a loss to conceive why he attributed all present variation of species to atavism, i.e., to the reappearance of ancestral characters (American Journal of Science, February, 1876). His anterior paper was not then known to us; from which it now appears that this view comes in as a part of the hypothesis of extreme plasticity and variability at the first, subsiding at length into entire fixity and persistence of character. According to which, it is assumed that the species of our time have lost all power of original variation, but can still reproduce some old ones--some reminiscences, as it were, of youthful vagaries--in the way of atavism. XIII-1. London, 1862. XIII-2. Hume, in his "Essays," anticipated this argument. But he did not rest on it. His matured convictions appear to be expressed in statements such as the following, here cited at second hand from Jackson's "Philosophy of Natural Theology," a volume to which a friend has just called our attention: "Though the stupidity of men," writes Hume, "barbarous and uninstructed, be so great that they may not see a sovereign author in the more obvious works of Nature, to which they are so much familiarized, yet it scarce seems possible that any one of good understanding should reject that idea, when once it is suggested to him. A purpose, an intention, a design, is evident in everything; and when our comprehension is so far enlarged as to contemplate the first rise of this visible system, we must adopt, with the strongest conviction, the idea of some intelligent cause or author. The uniform maxims, too, which prevail throughout the whole frame of the universe, naturally, if not necessarily, lead us to conceive this intelligence as single and undivided, where the prejudices of education oppose not so reasonable a theory. Even the contrarieties of Nature, by discovering themselves everywhere, become proofs of some consistent plan, and establish one single purpose or intention, however inexplicable and incomprehensible."---("Natural History of Religion," xv.) "In many views of the universe, and of its parts, particularly the latter, the beauty and fitness of final causes strike us with such irresistible force that all objections appear (what I believe they really are) mere cavils and sophisms."-- ("Dialogues concerning Natural Religion," Part X.) "The order and arrangement of Nature, the curious adjustment of final causes, the plain use and intention of every part and organ, all these bespeak in the clearest language an intelligent cause or author."--(Ibid., Part IV.) XIII-3. See Section I, Chapter 12. XIII-4. "No single and limited good can be assigned by us as the final cause of any contrivance in Nature. The real final cause . . . is the sum of all the uses to which it is ever to be put. Any use to which a contrivance of Nature is put, we may be sure, is a part of its final cause."--(G. F. Wright, in The New-Englander, October, 1871.) XIII-5. "No single and limited good can be assigned by us as the final cause of any contrivance in Nature. The real final cause . . . is the sum of all the uses to which it is ever to be put. Any use to which a contrivance of Nature is put, we may be sure, is a part of its final cause."--(G. F. Wright, in The New-Englander, October, 1871.) 
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Thomas Henry Huxley Collected Essays (1893-1894) Vol. II Darwiniana (Edition: published in 1893) PREFACE I have entitled this volume "Darwiniana" because the pieces republished in it either treat of the ancient doctrine of Evolution, rehabilitated and placed upon a sound scientific foundation, since and in consequence of, the publication of the "Origin of Species;" or they attempt to meet the more weighty of the unsparing criticisms with which that great work was visited for several years after its appearance; or they record the impression left by the personality of Mr. Darwin on one who had the privilege and the happiness of enjoying his friendship for some thirty years; or they endeavour to sum up his work and indicate its enduring influence on the course of scientific thought. Those who take the trouble to read the first two essays, published in 1859 and 1860, will, I think, do me the justice to admit that my zeal to secure fair play for Mr. Darwin, did not drive me into the position of a mere advocate; and that, while doing justice to the greatness of the argument I did not fail to indicate its weak points. I have never seen any reason for departing from the position which I took up in these two essays; and the assertion which I sometimes meet with nowadays, that I have "recanted" or changed my opinions about Mr. Darwin's views, is quite unintelligible to me. As I have said in the seventh essay, the fact of evolution is to my mind sufficiently evidenced by palaeontology; and I remain of the opinion expressed in the second, that until selective breeding is definitely proved to give rise to varieties infertile with one another, the logical foundation of the theory of natural selection is incomplete. We still remain very much in the dark about the causes of variation; the apparent inheritance of acquired characters in some cases; and the struggle for existence within the organism, which probably lies at the bottom of both of these phenomena. Some apology is due to the reader for the reproduction of the "Lectures to Working Men" in their original state. They were taken down in shorthand by Mr. J. Aldous Mays, who requested me to allow him to print them. I was very much pressed with work at the time; and, as I could not revise the reports, which I imagined, moreover, would be of little or no interest to any but my auditors, I stipulated that a notice should be prefixed to that effect. This was done; but it did not prevent a considerable diffusion of the little book in this country and in the United States, nor its translation into more than one foreign language. Moreover Mr. Darwin often urged me to revise and expand the lectures into a systematic popular exposition of the topics of which they treat. I have more than once set about the task: but the proverb about spoiling a horn and not making a spoon, is particularly applicable to attempts to remodel a piece of work which may have served its immediate purpose well enough. So I have reprinted the lectures as they stand, with all their imperfections on their heads. It would seem that many people must have found them useful thirty years ago; and, though the sixties appear now to be reckoned by many of the rising generation as a part of the dark ages, I am not without some grounds for suspecting that there yet remains a fair sprinkling even of "philosophic thinkers" to whom it may be a profitable, perhaps even a novel, task to descend from the heights of speculation and go over the A B C of the great biological problem as it was set before a body of shrewd artisans at that remote epoch. T. H. H. Hodeslea, Eastbourne, _April 7th_, 1893. CONTENTS I THE DARWINIAN HYPOTHESIS [1859] II THE ORIGIN OF SPECIES [1860] III CRITICISM ON "THE ORIGIN OF SPECIES" [1864] IV THE GENEALOGY OF ANIMALS [1869] V MR. DARWIN'S CRITICS [1871] VI EVOLUTION IN BIOLOGY [1878] VII THE COMING OF AGE OF "THE ORIGIN OF SPECIES" [1880] VIII CHARLES DARWIN [1882] IX THE DARWIN MEMORIAL [1885] X OBITUARY [1888] XI SIX LECTURES TO WORKING MEN "ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE" [1863] I THE DARWINIAN HYPOTHESIS [1859] The hypothesis of which the present work of Mr. Darwin is but the preliminary outline, may be stated in his own language as follows:-- "Species originated by means of natural selection, or through the preservation of the favoured races in the struggle for life." To render this thesis intelligible, it is necessary to interpret its terms. In the first place, what is a species? The question is a simple one, but the right answer to it is hard to find, even if we appeal to those who should know most about it. It is all those animals or plants which have descended from a single pair of parents; it is the smallest distinctly definable group of living organisms; it is an eternal and immutable entity; it is a mere abstraction of the human intellect having no existence in nature. Such are a few of the significations attached to this simple word which may be culled from authoritative sources; and if, leaving terms and theoretical subtleties aside, we turn to facts and endeavour to gather a meaning for ourselves, by studying the things to which, in practice, the name of species is applied, it profits us little. For practice varies as much as theory. Let two botanists or two zoologists examine and describe the productions of a country, and one will pretty certainly disagree with the other as to the number, limits, and definitions of the species into which he groups the very same things. In these islands, we are in the habit of regarding mankind as of one species, but a fortnight's steam will land us in a country where divines and savants, for once in agreement, vie with one another in loudness of assertion, if not in cogency of proof, that men are of different species; and, more particularly, that the species negro is so distinct from our own that the Ten Commandments have actually no reference to him. Even in the calm region of entomology, where, if anywhere in this sinful world, passion and prejudice should fail to stir the mind, one learned coleopterist will fill ten attractive volumes with descriptions of species of beetles, nine-tenths of which are immediately declared by his brother beetle-mongers to be no species at all. The truth is that the number of distinguishable living creatures almost surpasses imagination. At least 100,000 such kinds of insects alone have been described and may be identified in collections, and the number of separable kinds of living things is under-estimated at half a million. Seeing that most of these obvious kinds have their accidental varieties, and that they often shade into others by imperceptible degrees, it may well be imagined that the task of distinguishing between what is permanent and what fleeting, what is a species and what a mere variety, is sufficiently formidable. But is it not possible to apply a test whereby a true species may be known from a mere variety? Is there no criterion of species? Great authorities affirm that there is--that the unions of members of the same species are always fertile, while those of distinct species are either sterile, or their offspring, called hybrids, are so. It is affirmed not only that this is an experimental fact, but that it is a provision for the preservation of the purity of species. Such a criterion as this would be invaluable; but, unfortunately, not only is it not obvious how to apply it in the great majority of cases in which its aid is needed, but its general validity is stoutly denied. The Hon. and Rev. Mr. Herbert, a most trustworthy authority, not only asserts as the result of his own observations and experiments that many hybrids are quite as fertile as the parent species, but he goes so far as to assert that the particular plant _Crinum capense_ is much more fertile when crossed by a distinct species than when fertilised by its proper pollen! On the other hand, the famous Gaertner, though he took the greatest pains to cross the Primrose and the Cowslip, succeeded only once or twice in several years; and yet it is a well-established fact that the Primrose and the Cowslip are only varieties of the same kind of plant. Again, such cases as the following are well established. The female of species A, if crossed with the male of species B, is fertile; but, if the female of B is crossed with the male of A, she remains barren. Facts of this kind destroy the value of the supposed criterion. If, weary of the endless difficulties involved in the determination of species, the investigator, contenting himself with the rough practical distinction of separable kinds, endeavours to study them as they occur in nature--to ascertain their relations to the conditions which surround them, their mutual harmonies and discordancies of structure, the bond of union of their present and their past history, he finds himself, according to the received notions, in a mighty maze, and with, at most, the dimmest adumbration of a plan. If he starts with any one clear conviction, it is that every part of a living creature is cunningly adapted to some special use in its life. Has not his Paley told him that that seemingly useless organ, the spleen, is beautifully adjusted as so much packing between the other organs? And yet, at the outset of his studies, he finds that no adaptive reason whatsoever can be given for one-half of the peculiarities of vegetable structure. He also discovers rudimentary teeth, which are never used, in the gums of the young calf and in those of the foetal whale; insects which never bite have rudimental jaws, and others which never fly have rudimental wings; naturally blind creatures have rudimental eyes; and the halt have rudimentary limbs. So, again, no animal or plant puts on its perfect form at once, but all have to start from the same point, however various the course which each has to pursue. Not only men and horses, and cats and dogs, lobsters and beetles, periwinkles and mussels, but even the very sponges and animalcules commence their existence under forms which are essentially undistinguishable; and this is true of all the infinite variety of plants. Nay, more, all living beings march, side by side, along the high road of development, and separate the later the more like they are; like people leaving church, who all go down the aisle, but having reached the door, some turn into the parsonage, others go down the village, and others part only in the next parish. A man in his development runs for a little while parallel with, though never passing through, the form of the meanest worm, then travels for a space beside the fish, then journeys along with the bird and the reptile for his fellow travellers: and only at last, after a brief companionship with the highest of the four-footed and four-handed world, rises into the dignity of pure manhood. No competent thinker of the present day dreams of explaining these indubitable facts by the notion of the existence of unknown and undiscoverable adaptations to purpose. And we would remind those who, ignorant of the facts, must be moved by authority, that no one has asserted the incompetence of the doctrine of final causes, in its application to physiology and anatomy, more strongly than our own eminent anatomist, Professor Owen, who, speaking of such cases, says ("On the Nature of Limbs," pp. 39, 40)--"I think it will be obvious that the principle of final adaptations fails to satisfy all the conditions of the problem." But, if the doctrine of final causes will not help us to comprehend the anomalies of living structure, the principle of adaptation must surely lead us to understand why certain living beings are found in certain regions of the world and not in others. The Palm, as we know, will not grow in our climate, nor the Oak in Greenland. The white bear cannot live where the tiger thrives, nor _vice versâ_, and the more the natural habits of animal and vegetable species are examined, the more do they seem, on the whole, limited to particular provinces. But when we look into the facts established by the study of the geographical distribution of animals and plants it seems utterly hopeless to attempt to understand the strange and apparently capricious relations which they exhibit. One would be inclined to suppose _à priori_ that every country must be naturally peopled by those animals that are fittest to live and thrive in it. And yet how, on this hypothesis, are we to account for the absence of cattle in the Pampas of South America, when those parts of the New World were discovered? It is not that they were unfit for cattle, for millions of cattle now run wild there; and the like holds good of Australia and New Zealand. It is a curious circumstance, in fact, that the animals and plants of the Northern Hemisphere are not only as well adapted to live in the Southern Hemisphere as its own autochthones, but are, in many cases, absolutely better adapted, and so overrun and extirpate the aborigines. Clearly, therefore, the species which naturally inhabit a country are not necessarily the best adapted to its climate and other conditions. The inhabitants of islands are often distinct from any other known species of animal or plants (witness our recent examples from the work of Sir Emerson Tennent, on Ceylon), and yet they have almost always a sort of general family resemblance to the animals and plants of the nearest mainland. On the other hand, there is hardly a species of fish, shell, or crab common to the opposite sides of the narrow isthmus of Panama. [Footnote: See page 60 _Note_.] Wherever we look, then, living nature offers us riddles of difficult solution, if we suppose that what we see is all that can be known of it. But our knowledge of life is not confined to the existing world. Whatever their minor differences, geologists are agreed as to the vast thickness of the accumulated strata which compose the visible part of our earth, and the inconceivable immensity of the time the lapse of which they are the imperfect but the only accessible witnesses. Now, throughout the greater part of this long series of stratified rocks are scattered, sometimes very abundantly, multitudes of organic remains, the fossilised exuviæ of animals and plants which lived and died while the mud of which the rocks are formed was yet soft ooze, and could receive and bury them. It would be a great error to suppose that these organic remains were fragmentary relics. Our museums exhibit fossil shells of immeasurable antiquity, as perfect as the day they were formed; whole skeletons without a limb disturbed; nay, the changed flesh, the developing embryos, and even the very footsteps of primæval organisms. Thus the naturalist finds in the bowels of the earth species as well defined as, and in some groups of animals more numerous than, those which breathe the upper air. But, singularly enough, the majority of these entombed species are wholly distinct from those that now live. Nor is this unlikeness without its rule and order. As a broad fact, the further we go back in time the less the buried species are like existing forms; and, the further apart the sets of extinct creatures are, the less they are like one another. In other words, there has been a regular succession of living beings, each younger set, being in a very broad and general sense, somewhat more like those which now live. It was once supposed that this succession had been the result of vast successive catastrophes, destructions, and re-creations _en masse_; but catastrophes are now almost eliminated from geological, or at least palæontological speculation; and it is admitted, on all hands, that the seeming breaks in the chain of being are not absolute, but only relative to our imperfect knowledge; that species have replaced species, not in assemblages, but one by one; and that, if it were possible to have all the phenomena of the past presented to us, the convenient epochs and formations of the geologist, though having a certain distinctness, would fade into one another with limits as undefinable as those of the distinct and yet separable colours of the solar spectrum. Such is a brief summary of the main truths which have been established concerning species. Are these truths ultimate and irresolvable facts, or are their complexities and perplexities the mere expressions of a higher law? A large number of persons practically assume the former position to be correct. They believe that the writer of the Pentateuch was empowered and commissioned to teach us scientific as well as other truth, that the account we find there of the creation of living things is simply and literally correct, and that anything which seems to contradict it is, by the nature of the case, false. All the phenomena which have been detailed are, on this view, the immediate product of a creative fiat and, consequently, are out of the domain of science altogether. Whether this view prove ultimately to be true or false, it is, at any rate, not at present supported by what is commonly regarded as logical proof, even if it be capable of discussion by reason; and hence we consider ourselves at liberty to pass it by, and to turn to those views which profess to rest on a scientific basis only, and therefore admit of being argued to their consequences. And we do this with the less hesitation as it so happens that those persons who are practically conversant with the facts of the case (plainly a considerable advantage) have always thought fit to range themselves under the latter category. The majority of these competent persons have up to the present time maintained two positions--the first, that every species is, within certain defined limits, fixed and incapable of modification; the second, that every species was originally produced by a distinct creative act. The second position is obviously incapable of proof or disproof, the direct operations of the Creator not being subjects of science; and it must therefore be regarded as a corollary from the first, the truth or falsehood of which is a matter of evidence. Most persons imagine that the arguments in favour of it are overwhelming; but to some few minds, and these, it must be confessed, intellects of no small power and grasp of knowledge, they have not brought conviction. Among these minds, that of the famous naturalist Lamarck, who possessed a greater acquaintance with the lower forms of life than any man of his day, Cuvier not excepted, and was a good botanist to boot, occupies a prominent place. Two facts appear to have strongly affected the course of thought of this remarkable man--the one, that finer or stronger links of affinity connect all living beings with one another, and that thus the highest creature grades by multitudinous steps into the lowest; the other, that an organ may be developed in particular directions by exerting itself in particular ways, and that modifications once induced may be transmitted and become hereditary. Putting these facts together, Lamarck endeavoured to account for the first by the operation of the second. Place an animal in new circumstances, says he, and its needs will be altered; the new needs will create new desires, and the attempt to gratify such desires will result in an appropriate modification of the organs exerted. Make a man a blacksmith, and his brachial muscles will develop in accordance with the demands made upon them, and in like manner, says Lamarck, "the efforts of some short-necked bird to catch fish without wetting himself have, with time and perseverance, given rise to all our herons and long-necked waders." The Lamarckian hypothesis has long since been justly condemned, and it is the established practice for every tyro to raise his heel against the carcase of the dead lion. But it is rarely either wise or instructive to treat even the errors of a really great man with mere ridicule, and in the present case the logical form of the doctrine stands on a very different footing from its substance. If species have really arisen by the operation of natural conditions, we ought to be able to find those conditions now at work; we ought to be able to discover in nature some power adequate to modify any given kind of animal or plant in such a manner as to give rise to another kind, which would be admitted by naturalists as a distinct species. Lamarck imagined that he had discovered this _vera causa_ in the admitted facts that some organs may be modified by exercise; and that modifications, once produced, are capable of hereditary transmission. It does not seem to have occurred to him to inquire whether there is any reason to believe that there are any limits to the amount of modification producible, or to ask how long an animal is likely to endeavour to gratify an impossible desire. The bird, in our example, would surely have renounced fish dinners long before it had produced the least effect on leg or neck. Since Lamarck's time, almost all competent naturalists have left speculations on the origin of species to such dreamers as the author of the "Vestiges," by whose well-intentioned efforts the Lamarckian theory received its final condemnation in the minds of all sound thinkers. Notwithstanding this silence, however, the transmutation theory, as it has been called, has been a "skeleton in the closet" to many an honest zoologist and botanist who had a soul above the mere naming of dried plants and skins. Surely, has such an one thought, nature is a mighty and consistent whole, and the providential order established in the world of life must, if we could only see it rightly, be consistent with that dominant over the multiform shapes of brute matter. But what is the history of astronomy, of all the branches of physics, of chemistry, of medicine, but a narration of the steps by which the human mind has been compelled, often sorely against its will, to recognise the operation of secondary causes in events where ignorance beheld an immediate intervention of a higher power? And when we know that living things are formed of the same elements as the inorganic world, that they act and react upon it, bound by a thousand ties of natural piety, is it probable, nay is it possible, that they, and they alone, should have no order in their seeming disorder, no unity in their seeming multiplicity, should suffer no explanation by the discovery of some central and sublime law of mutual connection? Questions of this kind have assuredly often arisen, but it might have been long before they received such expression as would have commanded the respect and attention of the scientific world, had it not been for the publication of the work which prompted this article. Its author, Mr. Darwin, inheritor of a once celebrated name, won his spurs in science when most of those now distinguished were young men, and has for the last twenty years held a place in the front ranks of British philosophers. After a circumnavigatory voyage, undertaken solely for the love of his science, Mr. Darwin published a series of researches which at once arrested the attention of naturalists and geologists; his generalisations have since received ample confirmation and now command universal assent, nor is it questionable that they have had the most important influence on the progress of science. More recently Mr. Darwin, with a versatility which is among the rarest of gifts, turned his attention to a most difficult question of zoology and minute anatomy; and no living naturalist and anatomist has published a better monograph than that which resulted from his labours. Such a man, at all events, has not entered the sanctuary with unwashed hands, and when he lays before us the results of twenty years' investigation and reflection we must listen even though we be disposed to strike. But, in reading his work, it must be confessed that the attention which might at first be dutifully, soon becomes willingly, given, so clear is the author's thought, so outspoken his conviction, so honest and fair the candid expression of his doubts. Those who would judge the book must read it: we shall endeavour only to make its line of argument and its philosophical position intelligible to the general reader in our own way. The Baker Street Bazaar has just been exhibiting its familiar annual spectacle. Straight-backed, small-headed, big-barrelled oxen, as dissimilar from any wild species as can well be imagined, contended for attention and praise with sheep of half-a-dozen different breeds and styes of bloated preposterous pigs, no more like a wild boar or sow than a city alderman is like an ourang-outang. The cattle show has been, and perhaps may again be, succeeded by a poultry show, of whose crowing and clucking prodigies it can only be certainly predicated that they will be very unlike the aboriginal _Phasianus gallus._ If the seeker after animal anomalies is not satisfied, a turn or two in Seven Dials will convince him that the breeds of pigeons are quite as extraordinary and unlike one another and their parent stock, while the Horticultural Society will provide him with any number of corresponding vegetable aberrations from nature's types. He will learn with no little surprise, too, in the course of his travels, that the proprietors and producers of these animal and vegetable anomalies regard them as distinct species, with a firm belief, the strength of which is exactly proportioned to their ignorance of scientific biology, and which is the more remarkable as they are all proud of their skill in originating such "species." On careful inquiry it is found that all these, and the many other artificial breeds or races of animals and plants, have been produced by one method. The breeder--and a skilful one must be a person of much sagacity and natural or acquired perceptive faculty--notes some slight difference, arising he knows not how, in some individuals of his stock. If he wish to perpetuate the difference, to form a breed with the peculiarity in question strongly marked, he selects such male and female individuals as exhibit the desired character, and breeds from them. Their offspring are then carefully examined, and those which exhibit the peculiarity the most distinctly are selected for breeding; and this operation is repeated until the desired amount of divergence from the primitive stock is reached. It is then found that by continuing the process of selection--always breeding, that is, from well-marked forms, and allowing no impure crosses to interfere--a race may be formed, the tendency of which to reproduce itself is exceedingly strong; nor is the limit to the amount of divergence which may be thus produced known; but one thing is certain, that, if certain breeds of dogs, or of pigeons, or of horses, were known only in a fossil state, no naturalist would hesitate in regarding them as distinct species. But in all these cases we have human interference. Without the breeder there would be no selection, and without the selection no race. Before admitting the possibility of natural species having originated in any similar way, it must be proved that there is in Nature some power which takes the place of man, and performs a selection _suâ sponte._ It is the claim of Mr. Darwin that he professes to have discovered the existence and the _modus operandi_ of this "natural selection," as he terms it; and, if he be right, the process is perfectly simple and comprehensible, and irresistibly deducible from very familiar but well nigh forgotten facts. Who, for instance, has duly reflected upon all the consequences of the marvellous struggle for existence which is daily and hourly going on among living beings? Not only does every animal live at the expense of some other animal or plant, but the very plants are at war. The ground is full of seeds that cannot rise into seedlings; the seedlings rob one another of air, light and water, the strongest robber winning the day, and extinguishing his competitors. Year after year, the wild animals with which man never interferes are, on the average, neither more nor less numerous than they were; and yet we know that the annual produce of every pair is from one to perhaps a million young; so that it is mathematically certain that, on the average, as many are killed by natural causes as are born every year, and those only escape which happen to be a little better fitted to resist destruction than those which die. The individuals of a species are like the crew of a foundered ship, and none but good swimmers have a chance of reaching the land. Such being unquestionably the necessary conditions under which living creatures exist, Mr. Darwin discovers in them the instrument of natural selection. Suppose that in the midst of this incessant competition some individuals of a species (A) present accidental variations which happen to fit them a little better than their fellows for the struggle in which they are engaged, then the chances are in favour, not only of these individuals being better nourished than the others, but of their predominating over their fellows in other ways, and of having a better chance of leaving offspring, which will of course tend to reproduce the peculiarities of their parents. Their offspring will, by a parity of reasoning, tend to predominate over their contemporaries, and there being (suppose) no room for more than one species such as A, the weaker variety will eventually be destroyed by the new destructive influence which is thrown into the scale, and the stronger will take its place. Surrounding conditions remaining unchanged, the new variety (which we may call B)--supposed, for argument's sake, to be the best adapted for these conditions which can be got out of the original stock--will remain unchanged, all accidental deviations from the type becoming at once extinguished, as less fit for their post than B itself. The tendency of B to persist will grow with its persistence through successive generations, and it will acquire all the characters of a new species. But, on the other hand, if the conditions of life change in any degree, however slight, B may no longer be that form which is best adapted to withstand their destructive, and profit by their sustaining, influence; in which case if it should give rise to a more competent variety (C), this will take its place and become a new species; and thus, by natural selection, the species B and C will be successively derived from A. That this most ingenious hypothesis enables us to give a reason for many apparent anomalies in the distribution of living beings in time and space, and that it is not contradicted by the main phenomena of life and organisation appear to us to be unquestionable; and, so far, it must be admitted to have an immense advantage over any of its predecessors. But it is quite another matter to affirm absolutely either the truth or falsehood of Mr. Darwin's views at the present stage of the inquiry. Goethe has an excellent aphorism defining that state of mind which he calls "Thätige Skepsis"--active doubt. It is doubt which so loves truth that it neither dares rest in doubting, nor extinguish itself by unjustified belief; and we commend this state of mind to students of species, with respect to Mr. Darwin's or any other hypothesis, as to their origin. The combined investigations of another twenty years may, perhaps, enable naturalists to say whether the modifying causes and the selective power, which Mr. Darwin has satisfactorily shown to exist in Nature, are competent to produce all the effects he ascribes to them; or whether, on the other hand, he has been led to over-estimate the value of the principle of natural selection, as greatly as Lamarck over-estimated his _vera causa_ of modification by exercise. But there is, at all events, one advantage possessed by the more recent writer over his predecessor. Mr. Darwin abhors mere speculation as nature abhors a vacuum. He is as greedy of cases and precedents as any constitutional lawyer, and all the principles he lays down are capable of being brought to the test of observation and experiment. The path he bids us follow professes to be, not a mere airy track, fabricated of ideal cobwebs, but a solid and broad bridge of facts. If it be so, it will carry us safely over many a chasm in our knowledge, and lead us to a region free from the snares of those fascinating but barren virgins, the Final Causes, against whom a high authority has so justly warned us. "My sons, dig in the vineyard," were the last words of the old man in the fable: and, though the sons found no treasure, they made their fortunes by the grapes. II THE ORIGIN OF SPECIES [1860] Mr. Darwin's long-standing and well-earned scientific eminence probably renders him indifferent to that social notoriety which passes by the name of success; but if the calm spirit of the philosopher have not yet wholly superseded the ambition and the vanity of the carnal man within him, he must be well satisfied with the results of his venture in publishing the "Origin of Species." Overflowing the narrow bounds of purely scientific circles, the "species question" divides with Italy and the Volunteers the attention of general society. Everybody has read Mr. Darwin's book, or, at least, has given an opinion upon its merits or demerits; pietists, whether lay or ecclesiastic, decry it with the mild railing which sounds so charitable; bigots denounce it with ignorant invective; old ladies of both sexes consider it a decidedly dangerous book, and even savants, who have no better mud to throw, quote antiquated writers to show that its author is no better than an ape himself; while every philosophical thinker hails it as a veritable Whitworth gun in the armoury of liberalism; and all competent naturalists and physiologists, whatever their opinions as to the ultimate fate of the doctrines put forth, acknowledge that the work in which they are embodied is a solid contribution to knowledge and inaugurates a new epoch in natural history. Nor has the discussion of the subject been restrained within the limits of conversation. When the public is eager and interested, reviewers must minister to its wants; and the genuine _littérateur_ is too much in the habit of acquiring his knowledge from the book he judges--as the Abyssinian is said to provide himself with steaks from the ox which carries him--to be withheld from criticism of a profound scientific work by the mere want of the requisite preliminary scientific acquirement; while, on the other hand, the men of science who wish well to the new views, no less than those who dispute their validity, have naturally sought opportunities of expressing their opinions. Hence it is not surprising that almost all the critical journals have noticed Mr. Darwin's work at greater or less length; and so many disquisitions, of every degree of excellence, from the poor product of ignorance, too often stimulated by prejudice, to the fair and thoughtful essay of the candid student of Nature, have appeared, that it seems an almost hopeless task to attempt to say anything new upon the question. But it may be doubted if the knowledge and acumen of prejudged scientific opponents, and the subtlety of orthodox special pleaders, have yet exerted their full force in mystifying the real issues of the great controversy which has been set afoot, and whose end is hardly likely to be seen by this generation; so that, at this eleventh hour, and even failing anything new, it may be useful to state afresh that which is true, and to put the fundamental positions advocated by Mr. Darwin in such a form that they may be grasped by those whose special studies lie in other directions. And the adoption of this course may be the more advisable, because, notwithstanding its great deserts, and indeed partly on account of them, the "Origin of Species" is by no means an easy book to read--if by reading is implied the full comprehension of an author's meaning. We do not speak jestingly in saying that it is Mr. Darwin's misfortune to know more about the question he has taken up than any man living. Personally and practically exercised in zoology, in minute anatomy, in geology; a student of geographical distribution, not on maps and in museums only, but by long voyages and laborious collection; having largely advanced each of these branches of science, and having spent many years in gathering and sifting materials for his present work, the store of accurately registered facts upon which the author of the "Origin of Species" is able to draw at will is prodigious. But this very superabundance of matter must have been embarrassing to a writer who, for the present, can only put forward an abstract of his views; and thence it arises, perhaps, that notwithstanding the clearness of the style, those who attempt fairly to digest the book find much of it a sort of intellectual pemmican--a mass of facts crushed and pounded into shape, rather than held together by the ordinary medium of an obvious logical bond; due attention will, without doubt, discover this bond, but it is often hard to find. Again, from sheer want of room, much has to be taken for granted which might readily enough be proved; and hence, while the adept, who can supply the missing links in the evidence from his own knowledge, discovers fresh proof of the singular thoroughness with which all difficulties have been considered and all unjustifiable suppositions avoided, at every reperusal of Mr. Darwin's pregnant paragraphs, the novice in biology is apt to complain of the frequency of what he fancies is gratuitous assumption. Thus while it may be doubted if, for some years, any one is likely to be competent to pronounce judgment on all the issues raised by Mr. Darwin, there is assuredly abundant room for him, who, assuming the humbler, though perhaps as useful, office of an interpreter between the "Origin of Species" and the public, contents himself with endeavouring to point out the nature of the problems which it discusses; to distinguish between the ascertained facts and the theoretical views which it contains; and finally, to show the extent to which the explanation it offers satisfies the requirements of scientific logic. At any rate, it is this office which we purpose to undertake in the following pages. It may be safely assumed that our readers have a general conception of the nature of the objects to which the word "species" is applied; but it has, perhaps, occurred to a few, even to those who are naturalists _ex professo_, to reflect, that, as commonly employed, the term has a double sense and denotes two very different orders of relations. When we call a group of animals, or of plants, a species, we may imply thereby, either that all these animals or plants have some common peculiarity of form or structure; or, we may mean that they possess some common functional character. That part of biological science which deals with form and structure is called Morphology--that which concerns itself with function, Physiology--so that we may conveniently speak of these two senses, or aspects, of "species"--the one as morphological, the other as physiological. Regarded from the former point of view, a species is nothing more than a kind of animal or plant, which is distinctly definable from all others, by certain constant, and not merely sexual, morphological peculiarities. Thus horses form a species, because the group of animals to which that name is applied is distinguished from all others in the world by the following constantly associated characters. They have--1, A vertebral column; 2, Mammae; 3, A placental embryo; 4, Four legs; 5, A single well-developed toe in each foot provided with a hoof; 6, A bushy tail; and 7, Callosities on the inner sides of both the fore and the hind legs. The asses, again, form a distinct species, because, with the same characters, as far as the fifth in the above list, all asses have tufted tails, and have callosities only on the inner side of the fore-legs. If animals were discovered having the general characters of the horse, but sometimes with callosities only on the fore-legs, and more or less tufted tails; or animals having the general characters of the ass, but with more or less bushy tails, and sometimes with callosities on both pairs of legs, besides being intermediate in other respects--the two species would have to be merged into one. They could no longer be regarded as morphologically distinct species, for they would not be distinctly definable one from the other. However bare and simple this definition of species may appear to be, we confidently appeal to all practical naturalists, whether zoologists, botanists, or palaeontologists, to say if, in the vast majority of cases, they know, or mean to affirm, anything more of the group of animals or plants they so denominate than what has just been stated. Even the most decided advocates of the received doctrines respecting species admit this. "I apprehend," says Professor Owen, [Footnote: "On the Osteology of the Chimpanzees and Orangs"; _Transactions of the Zoological Society_, 1858.] "that few naturalists nowadays, in describing and proposing a name for what they call 'a new _species_,' use that term to signify what was meant by it twenty or thirty years ago; that is, an originally distinct creation, maintaining its primitive distinction by obstructive generative peculiarities. The proposer of the new species now intends to state no more than he actually knows; as, for example, that the differences on which he founds the specific character are constant in individuals of both sexes, so far as observation has reached; and that they are not due to domestication or to artificially superinduced external circumstances, or to any outward influence within his cognizance; that the species is wild, or is such as it appears by Nature." If we consider, in fact, that by far the largest proportion of recorded existing species are known only by the study of their skins, or bones, or other lifeless exuviae; that we are acquainted with none, or next to none, of their physiological peculiarities, beyond those which can be deduced from their structure, or are open to cursory observation; and that we cannot hope to learn more of any of those extinct forms of life which now constitute no inconsiderable proportion of the known Flora and Fauna of the world: it is obvious that the definitions of these species can be only of a purely structural, or morphological, character. It is probable that naturalists would have avoided much confusion of ideas if they had more frequently borne the necessary limitations of our knowledge in mind. But while it may safely be admitted that we are acquainted with only the morphological characters of the vast majority of species--the functional or physiological, peculiarities of a few have been carefully investigated, and the result of that study forms a large and most interesting portion of the physiology of reproduction. The student of Nature wonders the more and is astonished the less, the more conversant he becomes with her operations; but of all the perennial miracles she offers to his inspection, perhaps the most worthy of admiration is the development of a plant or of an animal from its embryo. Examine the recently laid egg of some common animal, such as a salamander or newt. It is a minute spheroid in which the best microscope will reveal nothing but a structureless sac, enclosing a glairy fluid, holding granules in suspension. [Footnote: When this sentence was written, it was generally believed that the original nucleus of the egg (the germinal vesicle) disappeared. 1893.] But strange possibilities lie dormant in that semi-fluid globule. Let a moderate supply of warmth reach its watery cradle, and the plastic matter undergoes changes so rapid, yet so steady and purposelike in their succession, that one can only compare them to those operated by a skilled modeller upon a formless lump of clay. As with an invisible trowel, the mass is divided and subdivided into smaller and smaller portions, until it is reduced to an aggregation of granules not too large to build withal the finest fabrics of the nascent organism. And, then, it is as if a delicate finger traced out the line to be occupied by the spinal column, and moulded the contour of the body; pinching up the head at one end, the tail at the other, and fashioning flank and limb into due salamandrine proportions, in so artistic a way, that, after watching the process hour by hour, one is almost involuntarily possessed by the notion, that some more subtle aid to vision than an achromatic, would show the hidden artist, with his plan before him, striving with skilful manipulation to perfect his work. As life advances, and the young amphibian ranges the waters, the terror of his insect contemporaries, not only are the nutritious particles supplied by its prey, by the addition of which to its frame, growth takes place, laid down, each in its proper spot, and in such due proportion to the rest, as to reproduce the form, the colour, and the size, characteristic of the parental stock; but even the wonderful powers of reproducing lost parts possessed by these animals are controlled by the same governing tendency. Cut off the legs, the tail, the jaws, separately or all together, and, as Spallanzani showed long ago, these parts not only grow again, but the redintegrated limb is formed on the same type as those which were lost. The new jaw, or leg, is a newt's, and never by any accident more like that of a frog. What is true of the newt is true of every animal and of every plant; the acorn tends to build itself up again into a woodland giant such as that from whose twig it fell; the spore of the humblest lichen reproduces the green or brown incrustation which gave it birth; and at the other end of the scale of life, the child that resembled neither the paternal nor the maternal side of the house would be regarded as a kind of monster. So that the one end to which, in all living beings, the formative impulse is tending--the one scheme which the Archæus of the old speculators strives to carry out, seems to be to mould the offspring into the likeness of the parent. It is the first great law of reproduction, that the offspring tends to resemble its parent or parents, more closely than anything else. Science will some day show us how this law is a necessary consequence of the more general laws which govern matter; but, for the present, more can hardly be said than that it appears to be in harmony with them. We know that the phænomena of vitality are not something apart from other physical phænomena, but one with them; and matter and force are the two names of the one artist who fashions the living as well as the lifeless. Hence living bodies should obey the same great laws as other matter--nor, throughout Nature, is there a law of wider application than this, that a body impelled by two forces takes the direction of their resultant. But living bodies may be regarded as nothing but extremely complex bundles of forces held in a mass of matter, as the complex forces of a magnet are held in the steel by its coercive force; and, since the differences of sex are comparatively slight, or, in other words, the sum of the forces in each has a very similar tendency, their resultant, the offspring, may reasonably be expected to deviate but little from a course parallel to either, or to both. Represent the reason of the law to ourselves by what physical metaphor or analogy we will, however, the great matter is to apprehend its existence and the importance of the consequences deducible from it. For things which are like to the same are like to one another; and if, in a great series of generations, every offspring is like its parent, it follows that all the offspring and all the parents must be like one another; and that, given an original parental stock, with the opportunity of undisturbed multiplication, the law in question necessitates the production, in course of time, of an indefinitely large group, the whole of the members of which are at once very similar and are blood relations, having descended from the same parent, or pair of parents. The proof that all the members of any given group of animals, or plants, had thus descended, would be ordinarily considered sufficient to entitle them to the rank of physiological species, for most physiologists consider species to be definable as "the offspring of a single primitive stock." But though it is quite true that all those groups we call species _may_, according to the known laws of reproduction, have descended from a single stock, and though it is very likely they really have done so, yet this conclusion rests on deduction and can hardly hope to establish itself upon a basis of observation. And the primitiveness of the supposed single stock, which, after all, is the essential part of the matter, is not only a hypothesis, but one which has not a shadow of foundation, if by "primitive" be meant "independent of any other living being." A scientific definition, of which an unwarrantable hypothesis forms an essential part, carries its condemnation within itself; but, even supposing such a definition were, in form, tenable, the physiologist who should attempt to apply it in Nature would soon find himself involved in great, if not inextricable, difficulties. As we have said, it is indubitable that offspring _tend_ to resemble the parental organism, but it is equally true that the similarity attained never amounts to identity either in form or in structure. There is always a certain amount of deviation, not only from the precise characters of a single parent, but when, as in most animals and many plants, the sexes are lodged in distinct individuals, from an exact mean between the two parents. And indeed, on general principles, this slight deviation seems as intelligible as the general similarity, if we reflect how complex the co-operating "bundles of forces" are, and how improbable it is that, in any case, their true resultant shall coincide with any mean between the more obvious characters of the two parents. Whatever be its cause, however, the co-existence of this tendency to minor variation with the tendency to general similarity, is of vast importance in its bearing on the question of the origin of species. As a general rule, the extent to which an offspring differs from its parent is slight enough; but, occasionally, the amount of difference is much more strongly marked, and then the divergent offspring receives the name of a Variety. Multitudes, of what there is every reason to believe are such varieties, are known, but the origin of very few has been accurately recorded, and of these we will select two as more especially illustrative of the main features of variation. The first of them is that of the "Ancon" or "Otter" sheep, of which a careful account is given by Colonel David Humphreys, F.R.S., in a letter to Sir Joseph Banks, published in the "Philosophical Transactions" for 1813. It appears that one Seth Wright, the proprietor of a farm on the banks of the Charles River, in Massachusetts, possessed a flock of fifteen ewes and a ram of the ordinary kind. In the year 1791, one of the ewes presented her owner with a male lamb, differing, for no assignable reason, from its parents by a proportionally long body and short bandy legs, whence it was unable to emulate its relatives in those sportive leaps over the neighbours' fences, in which they were in the habit of indulging, much to the good farmer's vexation. The second case is that detailed by a no less unexceptionable authority than Réaumur, in his "Art de faire éclore les Poulets." A Maltese couple, named Kelleia, whose hands and feet were constructed upon the ordinary human model, had born to them a son, Gratio, who possessed six perfectly movable fingers on each hand, and six toes, not quite so well formed, on each foot. No cause could be assigned for the appearance of this unusual variety of the human species. Two circumstances are well worthy of remark in both these cases. In each, the variety appears to have arisen in full force, and, as it were, _per saltum_; a wide and definite difference appearing, at once, between the Ancon ram and the ordinary sheep; between the six-fingered and six-toed Gratio Kelleia and ordinary men. In neither case is it possible to point out any obvious reason for the appearance of the variety. Doubtless there were determining causes for these as for all other phenomena; but they do not appear, and we can be tolerably certain that what are ordinarily understood as changes in physical conditions, as in climate, in food, or the like, did not take place and had nothing to do with the matter. It was no case of what is commonly called adaptation to circumstances; but, to use a conveniently erroneous phrase, the variations arose spontaneously. The fruitless search after final causes leads their pursuers a long way; but even those hardy teleologists, who are ready to break through all the laws of physics in chase of their favourite will-o'-the-wisp, may be puzzled to discover what purpose could be attained by the stunted legs of Seth Wright's ram or the hexadactyle members of Gratio Kelleia. Varieties then arise we know not why; and it is more than probable that the majority of varieties have arisen in this "spontaneous" manner, though we are, of course, far from denying that they may be traced, in some cases, to distinct external influences; which are assuredly competent to alter the character of the tegumentary covering, to change colour, to increase or diminish the size of muscles, to modify constitution, and, among plants, to give rise to the metamorphosis of stamens into petals, and so forth. But however they may have arisen, what especially interests us at present is, to remark that, once in existence, many varieties obey the fundamental law of reproduction that like tends to produce like; and their offspring exemplify it by tending to exhibit the same deviation from the parental stock as themselves. Indeed, there seems to be, in many instances, a prepotent influence about a newly-arisen variety which gives it what one may call an unfair advantage over the normal descendants from the same stock. This is strikingly exemplified by the case of Gratio Kelleia, who married a woman with the ordinary pentadactyle extremities, and had by her four children, Salvator, George, André, and Marie. Of these children Salvator, the eldest boy, had six fingers and six toes, like his father; the second and third, also boys, had five fingers and five toes, like their mother, though the hands and feet of George were slightly deformed. The last, a girl, had five fingers and five toes, but the thumbs were slightly deformed. The variety thus reproduced itself purely in the eldest, while the normal type reproduced itself purely in the third, and almost purely in the second and last: so that it would seem, at first, as if the normal type were more powerful than the variety. But all these children grew up and intermarried with normal wives and husband, and then, note what took place: Salvator had four children, three of whom exhibited the hexadactyle members of their grandfather and father, while the youngest had the pentadactyle limbs of the mother and grandmother; so that here, notwithstanding a double pentadactyle dilution of the blood, the hexadactyle variety had the best of it. The same pre-potency of the variety was still more markedly exemplified in the progeny of two of the other children, Marie and George. Marie (whose thumbs only were deformed) gave birth to a boy with six toes, and three other normally formed children; but George, who was not quite so pure a pentadactyle, begot, first, two girls, each of whom had six fingers and toes; then a girl with six fingers on each hand and six toes on the right foot, but only five toes on the left; and lastly, a boy with only five fingers and toes. In these instances, therefore, the variety, as it were, leaped over one generation to reproduce itself in full force in the next. Finally, the purely pentadactyle André was the father of many children, not one of whom departed from the normal parental type. If a variation which approaches the nature of a monstrosity can strive thus forcibly to reproduce itself, it is not wonderful that less aberrant modifications should tend to be preserved even more strongly; and the history of the Ancon sheep is, in this respect, particularly instructive. With the "'cuteness" characteristic of their nation, the neighbours of the Massachusetts farmer imagined it would be an excellent thing if all his sheep were imbued with the stay-at-home tendencies enforced by Nature upon the newly-arrived ram; and they advised Wright to kill the old patriarch of his fold, and install the Ancon ram in his place. The result justified their sagacious anticipations, and coincided very nearly with what occurred to the progeny of Gratio Kelleia. The young lambs were almost always either pure Ancons, or pure ordinary sheep.[Footnote: Colonel Humphreys' statements are exceedingly explicit on this point:--. "When an Ancon ewe is impregnated by a common ram, the increase resembles wholly either the ewe or the ram. The increase of the common ewe impregnated by an Ancon ram follows entirely the one or the other, without blending any of the distinguishing and essential peculiarities of both. Frequent instances have happened where common ewes have had twins by Ancon rams, when one exhibited the complete marks and features of the ewe, the other of the ram. The contrast has been rendered singularly striking, when one short-legged and one long-legged lamb, produced at a birth, have been seen sucking the dam at the same time."--_Philosophical Transactions_, 1813, Ft. I. pp. 89, 90.] But when sufficient Ancon sheep were obtained to interbreed with one another, it was found that the offspring was always pure Ancon. Colonel Humphreys, in fact, states that he was acquainted with only "one questionable case of a contrary nature." Here, then, is a remarkable and well-established instance, not only of a very distinct race being established _per saltum_, but of that race breeding "true" at once, and showing no mixed forms, even when crossed with another breed. By taking care to select Ancons of both sexes, for breeding from, it thus became easy to establish an extremely well-marked race; so peculiar that, even when herded with other sheep, it was noted that the Ancons kept together. And there is every reason to believe that the existence of this breed might have been indefinitely protracted; but the introduction of the Merino sheep, which were not only very superior to the Ancons in wool and meat, but quite as quiet and orderly, led to the complete neglect of the new breed, so that, in 1813, Colonel Humphreys found it difficult to obtain the specimen, the skeleton of which was presented to Sir Joseph Banks. We believe that, for many years, no remnant of it has existed in the United States. Gratio Kelleia was not the progenitor of a race of six-fingered men, as Seth Wright's ram became a nation of Ancon sheep, though the tendency of the variety to perpetuate itself appears to have been fully as strong in the one case as in the other. And the reason of the difference is not far to seek. Seth Wright took care not to weaken the Ancon blood by matching his Ancon ewes with any but males of the same variety, while Gratio Kelleia's sons were too far removed from the patriarchal times to intermarry with their sisters; and his grand-children seem not to have been attracted by their six-fingered cousins. In other words, in the one example a race was produced, because, for several generations, care was taken to _select_ both parents of the breeding stock from animals exhibiting a tendency to vary in the same direction; while, in the other, no race was evolved, because no such selection was exercised. A race is a propagated variety; and as, by the laws of reproduction, offspring tend to assume the parental forms, they will be more likely to propagate a variation exhibited by both parents than that possessed by only one. There is no organ of the body of an animal which may not, and does not, occasionally, vary more or less from the normal type; and there is no variation which may not be transmitted and which, if selectively transmitted, may not become the foundation of a race. This great truth, sometimes forgotten by philosophers, has long been familiar to practical agriculturists and breeders; and upon it rest all the methods of improving the breeds of domestic animals, which, for the last century, have been followed with so much success in England. Colour, form, size, texture of hair or wool, proportions of various parts, strength or weakness of constitution, tendency to fatten or to remain lean, to give much or little milk, speed, strength, temper, intelligence, special instincts; there is not one of these characters the transmission of which is not an every-day occurrence within the experience of cattle-breeders, stock-farmers, horse-dealers, and dog and poultry fanciers. Nay, it is only the other day that an eminent physiologist, Dr. Brown-Séquard, communicated to the Royal Society his discovery that epilepsy, artificially produced in guinea-pigs, by a means which he has discovered, is transmitted to their offspring. [Footnote: Compare Weismann's _Essays Upon Heredity_, p. 310, _et seq_. 1893.] But a race, once produced, is no more a fixed and immutable entity than the stock whence it sprang; variations arise among its members, and as these variations are transmitted like any others, new races may be developed out of the pre-existing one _ad infinitum_, or, at least, within any limit at present determined. Given sufficient time and sufficiently careful selection, and the multitude of races which may arise from a common stock is as astonishing as are the extreme structural differences which they may present. A remarkable example of this is to be found in the rock-pigeon, which Mr. Darwin has, in our opinion, satisfactorily demonstrated to be the progenitor of all our domestic pigeons, of which there are certainly more than a hundred well-marked races. The most noteworthy of these races are, the four great stocks known to the "fancy" as tumblers, pouters, carriers, and fantails; birds which not only differ most singularly in size, colour, and habits, but in the form of the beak and of the skull; in the proportions of the beak to the skull; in the number of tail-feathers; in the absolute and relative size of the feet; in the presence or absence of the uropygial gland; in the number of vertebræ in the back; in short, in precisely those characters in which the genera and species of birds differ from one another. And it is most remarkable and instructive to observe, that none of these races can be shown to have been originated by the action of changes in what are commonly called external circumstances, upon the wild rock-pigeon. On the contrary, from time immemorial pigeon-fanciers have had essentially similar methods of treating their pets, which have been housed, fed, protected and cared for in much the same way in all pigeonries. In fact, there is no case better adapted than that of the pigeons to refute the doctrine which one sees put forth on high authority, that "no other characters than those founded on the development of bone for the attachment of muscles" are capable of variation. In precise contradiction of this hasty assertion, Mr. Darwin's researches prove that the skeleton of the wings in domestic pigeons has hardly varied at all from that of the wild type; while, on the other hand, it is in exactly those respects, such as the relative length of the beak and skull, the number of the vertebrae, and the number of the tail-feathers, in which muscular exertion can have no important influence, that the utmost amount of variation has taken place. We have said that the following out of the properties exhibited by physiological species would lead us into difficulties, and at this point they begin to be obvious; for if, as the result of spontaneous variation and of selective breeding, the progeny of a common stock may become separated into groups distinguished from one another by constant, not sexual, morphological characters, it is clear that the physiological definition of species is likely to clash with the morphological definition. No one would hesitate to describe the pouter and the tumbler as distinct species, if they were found fossil, or if their skins and skeletons were imported, as those of exotic wild birds commonly are--and without doubt, if considered alone, they are good and distinct morphological species. On the other hand, they are not physiological species, for they are descended from a common stock, the rock-pigeon. Under these circumstances, as it is admitted on all sides that races occur in Nature, how are we to know whether any apparently distinct animals are really of different physiological species, or not, seeing that the amount of morphological difference is no safe guide? Is there any test of a physiological species? The usual answer of physiologists is in the affirmative. It is said that such a test is to be found in the phænomena of hybridisation--in the results of crossing races, as compared with the results of crossing species. So far as the evidence goes at present, individuals, of what are certainly known to be mere races produced by selection, however distinct they may appear to be, not only breed freely together, but the offspring of such crossed races are perfectly fertile with one another. Thus, the spaniel and the greyhound, the dray-horse and the Arab, the pouter and the tumbler, breed together with perfect freedom, and their mongrels, if matched with other mongrels of the same kind, are equally fertile. On the other hand, there can be no doubt that the individuals of many natural species are either absolutely infertile if crossed with individuals of other species, or, if they give rise to hybrid offspring, the hybrids so produced are infertile when paired together. The horse and the ass, for instance, if so crossed, give rise to the mule, and there is no certain evidence of offspring ever having been produced by a male and female mule. The unions of the rock-pigeon and the ring-pigeon appear to be equally barren of result. Here, then, says the physiologist, we have a means of distinguishing any two true species from any two varieties. If a male and a female, selected from each group, produce offspring, and that offspring is fertile with others produced in the same way, the groups are races and not species. If, on the other hand, no result ensues, or if the offspring are infertile with others produced in the same way, they are true physiological species. The test would be an admirable one, if, in the first place, it were always practicable to apply it, and if, in the second, it always yielded results susceptible of a definite interpretation. Unfortunately, in the great majority of cases, this touchstone for species is wholly inapplicable. The constitution of many wild animals is so altered by confinement that they will not breed even with their own females, so that the negative results obtained from crosses are of no value; and the antipathy of wild animals of different species for one another, or even of wild and tame members of the same species, is ordinarily so great, that it is hopeless to look for such unions in Nature. The hermaphrodism of most plants, the difficulty in the way of insuring the absence of their own or the proper working of other pollen, are obstacles of no less magnitude in applying the test to them. And, in both animals and plants, is super-added the further difficulty, that experiments must be continued over a long time for the purpose of ascertaining the fertility of the mongrel or hybrid progeny, as well as of the first crosses from which they spring. Not only do these great practical difficulties lie in the way of applying the hybridisation test, but even when this oracle can be questioned, its replies are sometimes as doubtful as those of Delphi. For example, cases are cited by Mr. Darwin, of plants which are more fertile with the pollen of another species than with their own; and there are others, such as certain _Fuci,_ the male element of which will fertilise the ovule of a plant of distinct species, while the males of the latter species are ineffective with the females of the first. So that, in the last-named instance, a physiologist, who should cross the two species in one way, would decide that they were true species; while another, who should cross them in the reverse way, would, with equal justice, according to the rule, pronounce them to be mere races. Several plants, which there is great reason to believe are mere varieties, are almost sterile when crossed; while both animals and plants, which have always been regarded by naturalists as of distinct species, turn out, when the test is applied, to be perfectly fertile. Again, the sterility or fertility of crosses seems to bear no relation to the structural resemblances or differences of the members of any two groups. Mr. Darwin has discussed this question with singular ability and circumspection, and his conclusions are summed up as follows, at page 276 of his work:-- "First crosses between forms sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile. The sterility is of all degrees, and is often so slight that the two most careful experimentalists who have ever lived have come to diametrically opposite conclusions in ranking forms by this test. The sterility is innately variable in individuals of the same species, and is eminently susceptible of favourable and unfavourable conditions. The degree of sterility does not strictly follow systematic affinity, but is governed by several curious and complex laws. It is generally different and sometimes widely different, in reciprocal crosses between the same two species. It is not always equal in degree in a first cross, and in the hybrid produced from this cross. "In the same manner as in grafting trees, the capacity of one species or variety to take on another is incidental on generally unknown differences in their vegetative systems; so in crossing, the greater or less facility of one species to unite with another is incidental on unknown differences in their reproductive systems. There is no more reason to think that species have been specially endowed with various degrees of sterility to prevent them crossing and breeding in Nature, than to think that trees have been specially endowed with various and somewhat analogous degrees of difficulty in being grafted together, in order to prevent them becoming inarched in our forests. "The sterility of first crosses between pure species, which have their reproductive systems perfect, seems to depend on several circumstances; in some cases largely on the early death of the embryo. The sterility of hybrids which have their reproductive systems imperfect, and which have had this system and their whole organisation disturbed by being compounded of two distinct species, seems closely allied to that sterility which so frequently affects pure species when their natural conditions of life have been disturbed. This view is supported by a parallelism of another kind: namely, that the crossing of forms, only slightly different, is favourable to the vigour and fertility of the offspring; and that slight changes in the conditions of life are apparently favourable to the vigour and fertility of all organic beings. It is not surprising that the degree of difficulty in uniting two species, and the degree of sterility of their hybrid offspring, should generally correspond, though due to distinct causes; for both depend on the amount of difference of some kind between the species which are crossed. Nor is it surprising that the facility of effecting a first cross, the fertility of hybrids produced from it, and the capacity of being grafted together--though this latter capacity evidently depends on widely different circumstances--should all run to a certain extent parallel with the systematic affinity of the forms which are subjected to experiment; for systematic affinity attempts to express all kinds of resemblance between all species. "First crosses between forms known to be varieties, or sufficiently alike to be considered as varieties, and their mongrel offspring, are very generally, but not quite universally, fertile. Nor is this nearly general and perfect fertility surprising, when we remember how liable we are to argue in a circle with respect to varieties in a state of Nature; and when we remember that the greater number of varieties have been produced under domestication by the selection of mere external differences, and not of differences in the reproductive system. In all other respects, excluding fertility, there is a close general resemblance between hybrids and mongrels."--Pp. 276-8. We fully agree with the general tenor of this weighty passage; but forcible as are these arguments, and little as the value of fertility or infertility as a test of species may be, it must not be forgotten that the really important fact, so far as the inquiry into the origin of species goes, is, that there are such things in Nature as groups of animals and of plants, the members of which are incapable of fertile union with those of other groups; and that there are such things as hybrids, which are absolutely sterile when crossed with other hybrids. For, if such phænomena as these were exhibited by only two of those assemblages of living objects, to which the name of species (whether it be used in its physiological or in its morphological sense) is given, it would have to be accounted for by any theory of the origin of species, and every theory which could not account for it would be, so far, imperfect. Up to this point, we have been dealing with matters of fact, and the statements which we have laid before the reader would, to the best of our knowledge, be admitted to contain a fair exposition of what is at present known respecting the essential properties of species, by all who have studied the question. And whatever may be his theoretical views, no naturalist will probably be disposed to demur to the following summary of that exposition:-- Living beings, whether animals or plants, are divisible into multitudes of distinctly definable kinds, which are morphological species. They are also divisible into groups of individuals, which breed freely together, tending to reproduce their like, and are physiological species. Normally resembling their parents, the offspring of members of these species are still liable to vary; and the variation may be perpetuated by selection, as a race, which race, in many cases, presents all the characteristics of a morphological species. But it is not as yet proved that a race ever exhibits, when crossed with another race of the same species, those phænomena of hybridisation which are exhibited by many species when crossed with other species. On the other hand, not only is it not proved that all species give rise to hybrids infertile _inter se_, but there is much reason to believe that, in crossing, species exhibit every gradation from perfect sterility to perfect fertility. Such are the most essential characteristics of species. Even were man not one of them--a member of the same system and subject to the same laws--the question of their origin, their causal connexion, that is, with the other phænomena of the universe, must have attracted his attention, as soon as his intelligence had raised itself above the level of his daily wants. Indeed history relates that such was the case, and has embalmed for us the speculations upon the origin of living beings, which were among the earliest products of the dawning intellectual activity of man. In those early days positive knowledge was not to be had, but the craving after it needed, at all hazards, to be satisfied, and according to the country, or the turn of thought, of the speculator, the suggestion that all living things arose from the mud of the Nile, from a primeval egg, or from some more anthropomorphic agency, afforded a sufficient resting-place for his curiosity. The myths of Paganism are as dead as Osiris or Zeus, and the man who should revive them, in opposition to the knowledge of our time, would be justly laughed to scorn; but the coeval imaginations current among the rude inhabitants of Palestine, recorded by writers whose very name and age are admitted by every scholar to be unknown, have unfortunately not yet shared their fate, but, even at this day, are regarded by nine-tenths of the civilised world as the authoritative standard of fact and the criterion of the justice of scientific conclusions, in all that relates to the origin of things, and, among them, of species. In this nineteenth century, as at the dawn of modern physical science, the cosmogony of the semi-barbarous Hebrew is the incubus of the philosopher and the opprobrium of the orthodox. Who shall number the patient and earnest seekers after truth, from the days of Galileo until now, whose lives have been embittered and their good name blasted by the mistaken zeal of Bibliolaters? Who shall count the host of weaker men whose sense of truth has been destroyed in the effort to harmonise impossibilities--whose life has been wasted in the attempt to force the generous new wine of Science into the old bottles of Judaism, compelled by the outcry of the same strong party? It is true that if philosophers have suffered, their cause has been amply avenged. Extinguished theologians lie about the cradle of every science as the strangled snakes beside that of Hercules; and history records that whenever science and orthodoxy have been fairly opposed, the latter has been forced to retire from the lists, bleeding and crushed if not annihilated; scotched, if not slain. But orthodoxy is the Bourbon of the world of thought. It learns not, neither can it forget; and though, at present, bewildered and afraid to move, it is as willing as ever to insist that the first chapter of Genesis contains the beginning and the end of sound science; and to visit, with such petty thunderbolts as its half-paralysed hands can hurl, those who refuse to degrade Nature to the level of primitive Judaism. Philosophers, on the other hand, have no such aggressive tendencies. With eyes fixed on the noble goal to which "per aspera et ardua" they tend, they may, now and then, be stirred to momentary wrath by the unnecessary obstacles with which the ignorant, or the malicious, encumber, if they cannot bar, the difficult path; but why should their souls be deeply vexed? The majesty of Fact is on their side, and the elemental forces of Nature are working for them. Not a star comes to the meridian at its calculated time but testifies to the justice of their methods--their beliefs are "one with the falling rain and with the growing corn." By doubt they are established, and open inquiry is their bosom friend. Such men have no fear of traditions however venerable, and no respect for them when they become mischievous and obstructive; but they have better than mere antiquarian business in hand, and if dogmas, which ought to be fossil but are not, are not forced upon their notice, they are too happy to treat them as non-existent. * * * * * The hypotheses respecting the origin of species which profess to stand upon a scientific basis, and, as such, alone demand serious attention, are of two kinds. The one, the "special creation" hypothesis, presumes every species to have originated from one or more stocks, these not being the result of the modification of any other form of living matter--or arising by natural agencies--but being produced, as such, by a supernatural creative act. The other, the so-called "transmutation" hypothesis, considers that all existing species are the result of the modification of pre-existing species, and those of their predecessors, by agencies similar to those which at the present day produce varieties and races, and therefore in an altogether natural way; and it is a probable, though not a necessary consequence of this hypothesis, that all living beings have arisen from a single stock. With respect to the origin of this primitive stock, or stocks, the doctrine of the origin of species is obviously not necessarily concerned. The transmutation hypothesis, for example, is perfectly consistent either with the conception of a special creation of the primitive germ, or with the supposition of its having arisen, as a modification of inorganic matter, by natural causes. The doctrine of special creation owes its existence very largely to the supposed necessity of making science accord with the Hebrew cosmogony; but it is curious to observe that, as the doctrine is at present maintained by men of science, it is as hopelessly inconsistent with the Hebrew view as any other hypothesis. If there be any result which has come more clearly out of geological investigation than another, it is, that the vast series of extinct animals and plants is not divisible, as it was once supposed to be, into distinct groups, separated by sharply-marked boundaries. There are no great gulfs between epochs and formations--no successive periods marked by the appearance of plants, of water animals, and of land animals, _en masse_. Every year adds to the list of links between what the older geologists supposed to be widely separated epochs: witness the crags linking the drift with older tertiaries; the Maestricht beds linking the tertiaries with the chalk; the St. Cassian beds exhibiting an abundant fauna of mixed mesozoic and palaeozoic types, in rocks of an epoch once supposed to be eminently poor in life; witness, lastly, the incessant disputes as to whether a given stratum shall be reckoned devonian or carboniferous, silurian or devonian, cambrian or silurian. This truth is further illustrated in a most interesting manner by the impartial and highly competent testimony of M. Pictet, from whose calculations of what percentage of the genera of animals, existing in any formation, lived during the preceding formation, it results that in no case is the proportion less than _one-third_, or 33 per cent. It is the triassic formation, or the commencement of the mesozoic epoch, which has received the smallest inheritance from preceding ages. The other formations not uncommonly exhibit 60, 80, or even 94 per cent, of genera in common with those whose remains are imbedded in their predecessor. Not only is this true, but the subdivisions of each formation exhibit new species characteristic of, and found only in, them; and, in many cases, as in the lias for example, the separate beds of these subdivisions are distinguished by well-marked and peculiar forms of life. A section, a hundred feet thick, will exhibit, at different heights, a dozen species of ammonite, none of which passes beyond its particular zone of limestone, or clay, into the zone below it or into that above it; so that those who adopt the doctrine of special creation must be prepared to admit, that at intervals of time, corresponding with the thickness of these beds, the Creator thought fit to interfere with the natural course of events for the purpose of making a new ammonite. It is not easy to transplant oneself into the frame of mind of those who can accept such a conclusion as this, on any evidence short of absolute demonstration; and it is difficult to see what is to be gained by so doing, since, as we have said, it is obvious that such a view of the origin of living beings is utterly opposed to the Hebrew cosmogony. Deserving no aid from the powerful arm of Bibliolatry, then, does the received form of the hypothesis of special creation derive any support from science or sound logic? Assuredly not much. The arguments brought forward in its favour all take one form: If species were not supernaturally created, we cannot understand the facts _x_, or _y_, or _z_; we cannot understand the structure of animals or plants, unless we suppose they were contrived for special ends; we cannot understand the structure of the eye, except by supposing it to have been made to see with; we cannot understand instincts, unless we suppose animals to have been miraculously endowed with them. As a question of dialectics, it must be admitted that this sort of reasoning is not very formidable to those who are not to be frightened by consequences. It is an _argumentum ad ignorantiam_--take this explanation or be ignorant. But suppose we prefer to admit our ignorance rather than adopt a hypothesis at variance with all the teachings of Nature? Or, suppose for a moment we admit the explanation, and then seriously ask ourselves how much the wiser are we; what does the explanation explain? Is it any more than a grandiloquent way of announcing the fact, that we really know nothing about the matter? A phenomenon is explained when it is shown to be a case of some general law of Nature; but the supernatural interposition of the Creator can, by the nature of the case, exemplify no law, and if species have really arisen in this way, it is absurd to attempt to discuss their origin. Or, lastly, let us ask ourselves whether any amount of evidence which the nature of our faculties permits us to attain, can justify us in asserting that any phenomenon is out of the reach of natural causation. To this end it is obviously necessary that we should know all the consequences to which all possible combinations, continued through unlimited time, can give rise. If we knew these, and found none competent to originate species, we should have good ground for denying their origin by natural causation. Till we know them, any hypothesis is better than one which involves us in such miserable presumption. But the hypothesis of special creation is not only a mere specious mask for our ignorance; its existence in Biology marks the youth and imperfection of the science. For what is the history of every science but the history of the elimination of the notion of creative, or other interferences, with the natural order of the phænomena which are the subject-matter of that science? When Astronomy was young "the morning stars sang together for joy," and the planets were guided in their courses by celestial hands. Now, the harmony of the stars has resolved itself into gravitation according to the inverse squares of the distances, and the orbits of the planets are deducible from the laws of the forces which allow a schoolboy's stone to break a window. The lightning was the angel of the Lord; but it has pleased Providence, in these modern times, that science should make it the humble messenger of man, and we know that every flash that shimmers about the horizon on a summer's evening is determined by ascertainable conditions, and that its direction and brightness might, if our knowledge of these were great enough, have been calculated. The solvency of great mercantile companies rests on the validity of the laws which have been ascertained to govern the seeming irregularity of that human life which the moralist bewails as the most uncertain of things; plague, pestilence, and famine are admitted, by all but fools, to be the natural result of causes for the most part fully within human control, and not the unavoidable tortures inflicted by wrathful Omnipotence upon His helpless handiwork. Harmonious order governing eternally continuous progress--the web and woof of matter and force interweaving by slow degrees, without a broken thread, that veil which lies between us and the Infinite--that universe which alone we know or can know; such is the picture which science draws of the world, and in proportion as any part of that picture is in unison with the rest, so may we feel sure that it is rightly painted. Shall Biology alone remain out of harmony with her sister sciences? Such arguments against the hypothesis of the direct creation of species as these are plainly enough deducible from general considerations; but there are, in addition, phenomena exhibited by species themselves, and yet not so much a part of their very essence as to have required earlier mention, which are in the highest degree perplexing, if we adopt the popularly accepted hypothesis. Such are the facts of distribution in space and in time; the singular phenomena brought to light by the study of development; the structural relations of species upon which our systems of classification are founded; the great doctrines of philosophical anatomy, such as that of homology, or of the community of structural plan exhibited by large groups of species differing very widely in their habits and functions. The species of animals which inhabit the sea on opposite sides of the isthmus of Panama are wholly distinct;[Footnote: Recent investigations tend to show that this statement is not strictly accurate.--1870.] the animals and plants which inhabit islands are commonly distinct from those of the neighbouring mainlands, and yet have a similarity of aspect. The mammals of the latest tertiary epoch in the Old and New Worlds belong to the same genera, or family groups, as those which now inhabit the same great geographical area. The crocodilian reptiles which existed in the earliest secondary epoch were similar in general structure to those now living, but exhibit slight differences in their vertebræ, nasal passages, and one or two other points. The guinea-pig has teeth which are shed before it is born, and hence can never subserve the masticatory purpose for which they seem contrived, and, in like manner, the female dugong has tusks which never cut the gum. All the members of the same great group run through similar conditions in their development, and all their parts, in the adult state, are arranged according to the same plan. Man is more like a gorilla than a gorilla is like a lemur. Such are a few, taken at random, among the multitudes of similar facts which modern research has established; but when the student seeks for an explanation of them from the supporters of the received hypothesis of the origin of species, the reply he receives is, in substance, of Oriental simplicity and brevity--"Mashallah! it so pleases God!" There are different species on opposite sides of the isthmus of Panama, because they were created different on the two sides. The pliocene mammals are like the existing ones, because such was the plan of creation; and we find rudimental organs and similarity of plan, because it has pleased the Creator to set before Himself a "divine exemplar or archetype," and to copy it in His works; and somewhat ill, those who hold this view imply, in some of them. That such verbal hocus-pocus should be received as science will one day be regarded as evidence of the low state of intelligence in the nineteenth century, just as we amuse ourselves with the phraseology about Nature's abhorrence of a vacuum, wherewith Torricellis compatriots were satisfied to explain the rise of water in a pump. And be it recollected that this sort of satisfaction works not only negative but positive ill, by discouraging inquiry, and so depriving man of the usufruct of one of the most fertile fields of his great patrimony, Nature. The objections to the doctrine of the origin of species by special creation which have been detailed, must have occurred, with more or less force, to the mind of every one who has seriously and independently considered the subject. It is therefore no wonder that, from time to time, this hypothesis should have been met by counter hypotheses, all as well, and some better founded than itself; and it is curious to remark that the inventors of the opposing views seem to have been led into them as much by their knowledge of geology, as by their acquaintance with biology. In fact, when the mind has once admitted the conception of the gradual production of the present physical state of our globe, by natural causes operating through long ages of time, it will be little disposed to allow that living beings have made their appearance in another way, and the speculations of De Maillet and his successors are the natural complement of Scilla's demonstration of the true nature of fossils. A contemporary of Newton and of Leibnitz, sharing therefore in the intellectual activity of the remarkable age which witnessed the birth of modern physical science, Benoît de Maillet spent a long life as a consular agent of the French Government in various Mediterranean ports. For sixteen years, in fact, he held the office of Consul-General in Egypt, and the wonderful phenomena offered by the valley of the Nile appear to have strongly impressed his mind, to have directed his attention to all facts of a similar order which came within his observation, and to have led him to speculate on the origin of the present condition of our globe and of its inhabitants. But, with all his ardour for science, De Maillet seems to have hesitated to publish views which, notwithstanding the ingenious attempts to reconcile them with the Hebrew hypothesis contained in the preface to "Telliamed," were hardly likely to be received with favour by his contemporaries. But a short time had elapsed since more than one of the great anatomists and physicists of the Italian school had paid dearly for their endeavours to dissipate some of the prevalent errors; and their illustrious pupil, Harvey, the founder of modern physiology, had not fared so well, in a country less oppressed by the benumbing influences of theology, as to tempt any man to follow his example. Probably not uninfluenced by these considerations, his Catholic majesty's Consul-General for Egypt kept his theories to himself throughout a long life, for "Telliamed," the only scientific work which is known to have proceeded from his pen, was not printed till 1735, when its author had reached the ripe age of seventy-nine; and though De Maillet lived three years longer, his book was not given to the world before 1748. Even then it was anonymous to those who were not in the secret of the anagrammatic character of its title; and the preface and dedication are so worded as, in case of necessity, to give the printer a fair chance of falling back on the excuse that the work was intended for a mere _jeu d'esprit_. The speculations of the suppositious Indian sage, though quite as sound as those of many a "Mosaic Geology," which sells exceedingly well, have no great value if we consider them by the light of modern science. The waters are supposed to have originally covered the whole globe; to have deposited the rocky masses which compose its mountains by processes comparable to those which are now forming mud, sand, and shingle; and then to have gradually lowered their level, leaving the spoils of their animal and vegetable inhabitants embedded in the strata. As the dry land appeared, certain of the aquatic animals are supposed to have taken to it, and to have become gradually adapted to terrestrial and aërial modes of existence. But if we regard the general tenor and style of the reasoning in relation to the state of knowledge of the day, two circumstances appear very well worthy of remark. The first, that De Maillet had a notion of the modifiability of living forms (though without any precise information on the subject), and how such modifiability might account for the origin of species; the second, that he very clearly apprehended the great modern geological doctrine, so strongly insisted upon by Hutton, and so ably and comprehensively expounded by Lyell, that we must look to existing causes for the explanation of past geological events. Indeed, the following passage of the preface, in which De Maillet is supposed to speak of the Indian philosopher Telliamed, his _alter ego,_ might have been written by the most philosophical uniformitarian of the present day:-- "Ce qu'il y a d'étonnant, est que pour arriver à ces connaissances il semble avoir perverti l'ordre naturel, puisqu'au lieu de s'attacher d'abord à rechercher l'origine de notre globe il a commence par travailler à s'instruire de la nature. Mais à l'entendre, ce renversement de l'ordre a été pour lui l'effet d'un génie favorable qui l'a conduit pas à pas et comme par la main aux découvertes les plus sublimes. C'est en décomposant la substance de ce globe par tine anatomie exacte de toutes ses parties qu'il a premierement appris de quelles matières il était composé et quels arrangemens ces mêmes matières observaient entre elles. Ces lumieres jointes à l'esprit de comparaison toujours nécessaire à quiconque entreprend de percer les voiles dont la nature aime à se cacher, ont servi de guide à notre philosophe pour parvenir à des connoissances plus intéressantes. Par la matière et l'arrangement de ces compositions il prétend avoir reconnu quelle est la véritable origine de ce globe que nous habitons, comment et par qui il a été formé."-Pp. xix. xx. But De Maillet was before his age, and as could hardly fail to happen to one who speculated on a zoological and botanical question before Linnæus, and on a physiological problem before Haller, he fell into great errors here and there; and hence, perhaps, the general neglect of his work. Robinet's speculations are rather behind, than in advance of, those of De Maillet; and though Linnæus may have played with the hypothesis of transmutation, it obtained no serious support until Lamarck adopted it, and advocated it with great ability in his "Philosophie Zoologique." Impelled towards the hypothesis of the transmutation of species, partly by his general cosmological and geological views; partly by the conception of a graduated, though irregularly branching, scale of being, which had arisen out of his profound study of plants and of the lower forms of animal life, Lamarck, whose general line of thought often closely resembles that of De Maillet, made a great advance upon the crude and merely speculative manner in which that writer deals with the question of the origin of living beings, by endeavouring to find physical causes competent to effect that change of one species into another, which De Maillet had only supposed to occur. And Lamarck conceived that he had found in Nature such causes, amply sufficient for the purpose in view. It is a physiological fact, he says, that organs are increased in size by action, atrophied by inaction; it is another physiological fact that modifications produced are transmissible to offspring. Change the actions of an animal, therefore, and you will change its structure, by increasing the development of the parts newly brought into use and by the diminution of those less used; but by altering the circumstances which surround it you will alter its actions, and hence, in the long run, change of circumstance must produce change of organisation. All the species of animals, therefore, are, in Lamarck's view, the result of the indirect action of changes of circumstance, upon those primitive germs which he considered to have originally arisen, by spontaneous generation, within the waters of the globe. It is curious, however, that Lamarck should insist so strongly [Footnote: See _Phil. Zoologique_, vol. i. p. 222. et seq.] as he has done, that circumstances never in any degree directly modify the form or the organisation of animals, but only operate by changing their wants and consequently their actions; for he thereby brings upon himself the obvious question, How, then, do plants, which cannot be said to have wants or actions, become modified? To this he replies, that they are modified by the changes in their nutritive processes, which are effected by changing circumstances; and it does not seem to have occurred to him that such changes might be as well supposed to take place among animals. When we have said that Lamarck felt that mere speculation was not the way to arrive at the origin of species, but that it was necessary, in order to the establishment of any sound theory on the subject, to discover by observation or otherwise, some _vera causa_, competent to give rise to them; that he affirmed the true order of classification to coincide with the order of their development one from another; that he insisted on the necessity of allowing sufficient time, very strongly; and that all the varieties of instinct and reason were traced back by him to the same cause as that which has given rise to species, we have enumerated his chief contributions to the advance of the question. On the other hand, from his ignorance of any power in Nature competent to modify the structure of animals, except the development of parts, or atrophy of them, in consequence of a change of needs, Lamarck was led to attach infinitely greater weight than it deserves to this agency, and the absurdities into which he was led have met with deserved condemnation. Of the struggle for existence, on which, as we shall see, Mr. Darwin lays such great stress, he had no conception; indeed, he doubts whether there really are such things as extinct species, unless they be such large animals as may have met their death at the hands of man; and so little does he dream of there being any other destructive causes at work, that, in discussing the possible existence of fossil shells, he asks, "Pourquoi d'ailleurs seroient-ils perdues dès que l'homme n'a pu opérer leur destruction?" ("Phil. Zool.," vol. i. p. 77.) Of the influence of selection Lamarck has as little notion, and he makes no use of the wonderful phenomena which are exhibited by domesticated animals, and illustrate its powers. The vast influence of Cuvier was employed against the Lamarckian views, and, as the untenability of some of his conclusions was easily shown, his doctrines sank under the opprobrium of scientific, as well as of theological, heterodoxy. Nor have the efforts made of late years to revive them tended to re-establish their credit in the minds of sound thinkers acquainted with the facts of the case; indeed it may be doubted whether Lamarck has not suffered more from his friends than from his foes. Two years ago, in fact, though we venture to question if even the strongest supporters of the special creation hypothesis had not, now and then, an uneasy consciousness that all was not right, their position seemed more impregnable than ever, if not by its own inherent strength, at any rate by the obvious failure of all the attempts which had been made to carry it. On the other hand, however much the few, who thought deeply on the question of species, might be repelled by the generally received dogmas, they saw no way of escaping from them save by the adoption of suppositions so little justified by experiment or by observation as to be at least equally distasteful. The choice lay between two absurdities and a middle condition of uneasy scepticism; which last, however unpleasant and unsatisfactory, was obviously the only justifiable state of mind under the circumstances. Such being the general ferment in the minds of naturalists, it is no wonder that they mustered strong in the rooms of the Linnæan Society, on the 1st of July of the year 1858, to hear two papers by authors living on opposite sides of the globe, working out their results independently, and yet professing to have discovered one and the same solution of all the problems connected with species. The one of these authors was an able naturalist, Mr. Wallace, who had been employed for some years in studying the productions of the islands of the Indian Archipelago, and who had forwarded a memoir embodying his views to Mr. Darwin, for communication to the Linnæan Society. On perusing the essay, Mr. Darwin was not a little surprised to find that it embodied some of the leading ideas of a great work which he had been preparing for twenty years, and parts of which, containing a development of the very same views, had been perused by his private friends fifteen or sixteen years before. Perplexed in what manner to do full justice both to his friend and to himself, Mr. Darwin placed the matter in the hands of Dr. Hooker and Sir Charles Lyell, by whose advice he communicated a brief abstract of his own views to the Linnæan Society, at the same time that Mr. Wallace's paper was read. Of that abstract, the work on the "Origin of Species" is an enlargement; but a complete statement of Mr. Darwin's doctrine is looked for in the large and well-illustrated work which he is said to be preparing for publication. The Darwinian hypothesis has the merit of being eminently simple and comprehensible in principle, and its essential positions may be stated in a very few words: all species have been produced by the development of varieties from common stocks; by the conversion of these, first into permanent races and then into new species, by the process of _natural selection_, which process is essentially identical with that artificial selection by which man has originated the races of domestic animals--the _struggle for existence_ taking the place of man, and exerting, in the case of natural selection, that selective action which he performs in artificial selection. The evidence brought forward by Mr. Darwin in support of his hypothesis is of three kinds. First, he endeavours to prove that species may be originated by selection; secondly, he attempts to show that natural causes are competent to exert selection; and thirdly, he tries to prove that the most remarkable and apparently anomalous phænomena exhibited by the distribution, development, and mutual relations of species, can be shown to be deducible from the general doctrine of their origin, which he propounds, combined with the known facts of geological change; and that, even if all these phænomena are not at present explicable by it, none are necessarily inconsistent with it. There cannot be a doubt that the method of inquiry which Mr. Darwin has adopted is not only rigorously in accordance with the canons of scientific logic, but that it is the only adequate method. Critics exclusively trained in classics or in mathematics, who have never determined a scientific fact in their lives by induction from experiment or observation, prate learnedly about Mr. Darwin's method, which is not inductive enough, not Baconian enough, forsooth, for them. But even if practical acquaintance with the process of scientific investigation is denied them, they may learn, by the perusal of Mr. Mill's admirable chapter "On the Deductive Method," that there are multitudes of scientific inquiries in which the method of pure induction helps the investigator but a very little way. "The mode of investigation," says Mr. Mill, "which, from the proved inapplicability of direct methods of observation and experiment, remains to us as the main source of the knowledge we possess, or can acquire, respecting the conditions and laws of recurrence of the more complex phænomena, is called, in its most general expression, the deductive method, and consists of three operations: the first, one of direct induction; the second, of ratiocination; and the third, of verification." Now, the conditions which have determined the existence of species are not only exceedingly complex, but, so far as the great majority of them are concerned, are necessarily beyond our cognisance. But what Mr. Darwin has attempted to do is in exact accordance with the rule laid down by Mr. Mill; he has endeavoured to determine certain great facts inductively, by observation and experiment; he has then reasoned from the data thus furnished; and lastly, he has tested the validity of his ratiocination by comparing his deductions with the observed facts of Nature. Inductively, Mr. Darwin endeavours to prove that species arise in a given way. Deductively, he desires to show that, if they arise in that way, the facts of distribution, development, classification, &c., may be accounted for, _i.e._ may be deduced from their mode of origin, combined with admitted changes in physical geography and climate, during an indefinite period. And this explanation, or coincidence of observed with deduced facts, is, so far as it extends, a verification of the Darwinian view. There is no fault to be found with Mr. Darwin's method, then; but it is another question whether he has fulfilled all the conditions imposed by that method. Is it satisfactorily proved, in fact, that species may be originated by selection? that there is such a thing as natural selection? that none of the phænomena exhibited by species are inconsistent with the origin of species in this way? If these questions can be answered in the affirmative, Mr. Darwin's view steps out of the rank of hypotheses into those of proved theories; but, so long as the evidence at present adduced falls short of enforcing that affirmation, so long, to our minds, must the new doctrine be content to remain among the former--an extremely valuable, and in the highest degree probable, doctrine, indeed the only extant hypothesis which is worth anything in a scientific point of view; but still a hypothesis, and not yet the theory of species. After much consideration, and with assuredly no bias against Mr. Darwin's views, it is our clear conviction that, as the evidence stands, it is not absolutely proven that a group of animals, having all the characters exhibited by species in Nature, has ever been originated by selection, whether artificial or natural. Groups having the morphological character of species--distinct and permanent races in fact--have been so produced over and over again; but there is no positive evidence, at present, that any group of animals has, by variation and selective breeding, given rise to another group which was, even in the least degree, infertile with the first. Mr. Darwin is perfectly aware of this weak point, and brings forward a multitude of ingenious and important arguments to diminish the force of the objection. We admit the value of these arguments to their fullest extent; nay, we will go so far as to express our belief that experiments, conducted by a skilful physiologist, would very probably obtain the desired production of mutually more or less infertile breeds from a common stock, in a comparatively few years; but still, as the case stands at present, this "little rift within the lute" is not to be disguised nor overlooked. In the remainder of Mr. Darwin's argument our own private ingenuity has not hitherto enabled us to pick holes of any great importance; and judging by what we hear and read, other adventurers in the same field do not seem to have been much more fortunate. It has been urged, for instance, that in his chapters on the struggle for existence and on natural selection, Mr. Darwin does not so much prove that natural selection does occur, as that it must occur; but, in fact, no other sort of demonstration is attainable. A race does not attract our attention in Nature until it has, in all probability, existed for a considerable time, and then it is too late to inquire into the conditions of its origin. Again, it is said that there is no real analogy between the selection which takes place under domestication, by human influence, and any operation which can be effected by Nature, for man interferes intelligently. Reduced to its elements, this argument implies that an effect produced with trouble by an intelligent agent must, _à fortiori,_ be more troublesome, if not impossible, to an unintelligent agent. Even putting aside the question whether Nature, acting as she does according to definite and invariable laws, can be rightly called an unintelligent agent, such a position as this is wholly untenable. Mix salt and sand, and it shall puzzle the wisest of men, with his mere natural appliances, to separate all the grains of sand from all the grains of salt; but a shower of rain will effect the same object in ten minutes. And so, while man may find it tax all his intelligence to separate any variety which arises, and to breed selectively from it, the destructive agencies incessantly at work in Nature, if they find one variety to be more soluble in circumstances than the other, will inevitably, in the long run, eliminate it. A frequent and a just objection to the Lamarckian hypothesis of the transmutation of species is based upon the absence of transitional forms between many species. But against the Darwinian hypothesis this argument has no force. Indeed, one of the most valuable and suggestive parts of Mr. Darwin's work is that in which he proves, that the frequent absence of transitions is a necessary consequence of his doctrine, and that the stock whence two or more species have sprung, need in no respect be intermediate between these species. If any two species have arisen from a common stock in the same way as the carrier and the pouter, say, have arisen from the rock-pigeon, then the common stock of these two species need be no more intermediate between the two than the rock-pigeon is between the carrier and pouter. Clearly appreciate the force of this analogy, and all the arguments against the origin of species by selection, based on the absence of transitional forms, fall to the ground. And Mr. Darwin's position might, we think, have been even stronger than it is if he had not embarrassed himself with the aphorism, "_Natura non facit saltum_," which turns up so often in his pages. We believe, as we have said above, that Nature does make jumps now and then, and a recognition of the fact is of no small importance in disposing of many minor objections to the doctrine of transmutation. But we must pause. The discussion of Mr. Darwin's arguments in detail would lead us far beyond the limits within which we proposed, at starting, to confine this article. Our object has been attained if we have given an intelligible, however brief, account of the established facts connected with species, and of the relation of the explanation of those facts offered by Mr. Darwin to the theoretical views held by his predecessors and his contemporaries, and, above all, to the requirements of scientific logic. We have ventured to point out that it does not, as yet, satisfy all those requirements; but we do not hesitate to assert that it is as superior to any preceding or contemporary hypothesis, in the extent of observational and experimental basis on which it rests, in its rigorously scientific method, and in its power of explaining biological phenomena, as was the hypothesis of Copernicus to the speculations of Ptolemy. But the planetary orbits turned out to be not quite circular after all, and, grand as was the service Copernicus rendered to science, Kepler and Newton had to come after him. What if the orbit of Darwinism should be a little too circular? What if species should offer residual phænomena, here and there, not explicable by natural selection? Twenty years hence naturalists may be in a position to say whether this is, or is not, the case; but in either event they will owe the author of "The Origin of Species" an immense debt of gratitude. We should leave a very wrong impression on the reader's mind if we permitted him to suppose that the value of that work depends wholly on the ultimate justification of the theoretical views which it contains. On the contrary, if they were disproved to-morrow, the book would still be the best of its kind--the most compendious statement of well-sifted facts bearing on the doctrine of species that has ever appeared. The chapters on Variation, on the Struggle for Existence, on Instinct, on Hybridism, on the Imperfection of the Geological Record, on Geographical Distribution, have not only no equals, but, so far as our knowledge goes, no competitors, within the range of biological literature. And viewed as a whole, we do not believe that, since the publication of Von Baer's "Researches on Development," thirty years ago, any work has appeared calculated to exert so large an influence, not only on the future of Biology, but in extending the domination of Science over regions of thought into which she has, as yet, hardly penetrated. III CRITICISMS ON "THE ORIGIN OF SPECIES" [1864] 1. UEBER DIE DARWIN'SCHE SCHÖPFUNGSTHEORIE; EIN VORTRAG, Von A. KÖLLIKER. Leipzig, 1864. 2. EXAMINATION DU LIVRE DE M. DARWIN SUR L'ORIGINE DES ESPÈCES. Par P. FLOURENS. Paris, 1864. In the course of the present year several foreign commentaries upon Mr. Darwin's great work have made their appearance. Those who have perused that remarkable chapter of the "Antiquity of Man," in which Sir Charles Lyell draws a parallel between the development of species and that of languages, will be glad to hear that one of the most eminent philologers of Germany, Professor Schleicher, has, independently, published a most instructive and philosophical pamphlet (an excellent notice of which is to be found in the _Reader_, for February 27th of this year) supporting similar views with all the weight of his special knowledge and established authority as a linguist. Professor Haeckel, to whom Schleicher addresses himself, previously took occasion, in his splendid monograph on the _Radiolaria_,[Footnote: _Die Radiolarien: eine Monographie_, p. 231.] to express his high appreciation of, and general concordance with, Mr. Darwin's views. But the most elaborate criticisms of the "Origin of Species" which have appeared are two works of very widely different merit, the one by Professor Kölliker, the well-known anatomist and histologist of Würzburg; the other by M. Flourens, Perpetual Secretary of the French Academy of Sciences. Professor Kölliker's critical essay "Upon the Darwinian Theory" is, like all that proceeds from the pen of that thoughtful and accomplished writer, worthy of the most careful consideration. It comprises a brief but clear sketch of Darwin's views, followed by an enumeration of the leading difficulties in the way of their acceptance; difficulties which would appear to be insurmountable to Professor Kölliker, inasmuch as he proposes to replace Mr. Darwin's Theory by one which he terms the "Theory of Heterogeneous Generation." We shall proceed to consider first the destructive, and secondly, the constructive portion of the essay. We regret to find ourselves compelled to dissent very widely from many of Professor Kölliker's remarks; and from none more thoroughly than from those in which he seeks to define what we may term the philosophical position of Darwinism. "Darwin," says Professor Kölliker, "is, in the fullest sense of the word, a Teleologist. He says quite distinctly (First Edition, pp. 199, 200) that every particular in the structure of an animal has been created for its benefit, and he regards the whole series of animal forms only from this point of view." And again: "7. The teleological general conception adopted by Darwin is a mistaken one. "Varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent. "The assumption that an organism exists only on account of some definite end in view, and represents something more than the incorporation of a general idea, or law, implies a one-sided conception of the universe. Assuredly, every organ has, and every organism fulfils, its end, but its purpose is not the condition of its existence. Every organism is also sufficiently perfect for the purpose it serves, and in that, at least, it is useless to seek for a cause of its improvement." It is singular how differently one and the same book will impress different minds. That which struck the present writer most forcibly on his first perusal of the "Origin of Species" was the conviction that Teleology, as commonly understood, had received its deathblow at Mr. Darwin's hands. For the teleological argument runs thus: an organ or organism (A) is precisely fitted to perform a function or purpose (B); therefore it was specially constructed to perform that function. In Paley's famous illustration, the adaptation of all the parts of the watch to the function, or purpose, of showing the time, is held to be evidence that the watch was specially contrived to that end; on the ground, that the only cause we know of, competent to produce such an effect as a watch which shall keep time, is a contriving intelligence adapting the means directly to that end. Suppose, however, that any one had been able to show that the watch had not been made directly by any person, but that it was the result of the modification of another watch which kept time but poorly; and that this again had proceeded from a structure which could hardly be called a watch at all--seeing that it had no figures on the dial and the hands were rudimentary; and that going back and back in time we came at last to a revolving barrel as the earliest traceable rudiment of the whole fabric. And imagine that it had been possible to show that all these changes had resulted, first, from a tendency of the structure to vary indefinitely; and secondly, from something in the surrounding world which helped all variations in the direction of an accurate time-keeper, and checked all those in other directions; then it is obvious that the force of Paley's argument would be gone. For it would be demonstrated that an apparatus thoroughly well adapted to a particular purpose might be the result of a method of trial and error worked by unintelligent agents, as well as of the direct application of the means appropriate to that end, by an intelligent agent. Now it appears to us that what we have here, for illustration's sake, supposed to be done with the watch, is exactly what the establishment of Darwin's Theory will do for the organic world. For the notion that every organism has been created as it is and launched straight at a purpose, Mr. Darwin substitutes the conception of something which may fairly be termed a method of trial and error. Organisms vary incessantly; of these variations the few meet with surrounding conditions which suit them and thrive; the many are unsuited and become extinguished. According to Teleology, each organism is like a rifle bullet fired straight at a mark; according to Darwin, organisms are like grapeshot of which one hits something and the rest fall wide. For the teleologist an organism exists because it was made for the conditions in which it is found; for the Darwinian an organism exists because, out of many of its kind, it is the only one which has been able to persist in the conditions in which it is found. Teleology implies that the organs of every organism are perfect and cannot be improved; the Darwinian theory simply affirms that they work well enough to enable the organism to hold its own against such competitors as it has met with, but admits the possibility of indefinite improvement. But an example may bring into clearer light the profound opposition between the ordinary teleological, and the Darwinian, conception. Cats catch mice, small birds and the like, very well. Teleology tells us that they do so because they were expressly constructed for so doing--that they are perfect mousing apparatuses, so perfect and so delicately adjusted that no one of their organs could be altered, without the change involving the alteration of all the rest. Darwinism affirms on the contrary, that there was no express construction concerned in the matter; but that among the multitudinous variations of the Feline stock, many of which died out from want of power to resist opposing influences, some, the cats, were better fitted to catch mice than others, whence they throve and persisted, in proportion to the advantage over their fellows thus offered to them. Far from imagining that cats exist _in order_ to catch mice well, Darwinism supposes that cats exist because they catch mice well--mousing being not the end, but the condition, of their existence. And if the cat type has long persisted as we know it, the interpretation of the fact upon Darwinian principles would be, not that the cats have remained invariable, but that such varieties as have incessantly occurred have been, on the whole, less fitted to get on in the world than the existing stock. If we apprehend the spirit of the "Origin of Species" rightly, then, nothing can be more entirely and absolutely opposed to Teleology, as it is commonly understood, than the Darwinian Theory. So far from being a "Teleologist in the fullest sense of the word," we should deny that he is a Teleologist in the ordinary sense at all; and we should say that, apart from his merits as a naturalist, he has rendered a most remarkable service to philosophical thought by enabling the student of Nature to recognise, to their fullest extent, those adaptations to purpose which are so striking in the organic world, and which Teleology has done good service in keeping before our minds, without being false to the fundamental principles of a scientific conception of the universe. The apparently diverging teachings of the Teleologist and of the Morphologist are reconciled by the Darwinian hypothesis. But leaving our own impressions of the "Origin of Species," and turning to those passages especially cited by Professor Kölliker, we cannot admit that they bear the interpretation he puts upon them. Darwin, if we read him rightly, does _not_ affirm that every detail in the structure of an animal has been created for its benefit. His words are (p. 199):-- "The foregoing remarks lead me to say a few words on the protest lately made by some naturalists against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that very many structures have been created for beauty in the eyes of man, or for mere variety. This doctrine, if true, would be absolutely fatal to my theory--yet I fully admit that many structures are of no direct use to their possessor." And after sundry illustrations and qualifications, he concludes (p. 200):-- "Hence every detail of structure in every living creature (making some little allowance for the direct action of physical conditions) may be viewed either as having been of special use to some ancestral form, or as being now of special use to the descendants of this form--either directly, or indirectly, through the complex laws of growth." But it is one thing to say, Darwinically, that every detail observed in an animal's structure is of use to it, or has been of use to its ancestors; and quite another to affirm, teleologically, that every detail of an animal's structure has been created for its benefit. On the former hypothesis, for example, the teeth of the foetal _Baltæna_ have a meaning; on the latter, none. So far as we are aware, there is not a phrase in the "Origin of Species" inconsistent with Professor Kölliker's position, that "varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent." On the contrary, Mr. Darwin writes (Summary of Chap. V.):-- "Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part varies more or less from the same part in the parents... The external conditions of life, as climate and food, &c., seem to have induced some slight modifications. Habit, in producing constitutional differences, and use, in strengthening, and disuse, in weakening and diminishing organs, seem to have been more potent in their effects." And finally, as if to prevent all possible misconception, Mr. Darwin concludes his Chapter on Variation with these pregnant words:-- "Whatever the cause may be of each slight difference in the offspring from their parents--and a cause for each must exist--it is the steady accumulation, through natural selection of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure, by which the innumerable beings on the face of the earth are enabled to struggle with each other, and the best adapted to survive." We have dwelt at length upon, this subject, because of its great general importance, and because we believe that Professor Kölliker's criticisms on this head are based upon a misapprehension of Mr. Darwin's views--substantially they appear to us to coincide with his own. The other objections which Professor Kölliker enumerates and discusses are the following: [Footnote: Space will not allow us to give Professor Kölliker's arguments in detail; our readers will find a full and accurate version of them in the _Reader_ for August 13th and 20th, 1864.]-- "1. No transitional forms between existing species are known; and known varieties, whether selected or spontaneous, never go so far as to establish new species." To this Professor Kölliker appears to attach some weight. He makes the suggestion that the short-faced tumbler pigeon may be a pathological product. "2. No transitional forms of animals are met with among the organic remains of earlier epochs." Upon this, Professor Kölliker remarks that the absence of transitional forms in the fossil world, though not necessarily fatal to Darwin's views, weakens his case. "3. The struggle for existence does not take place." To this objection, urged by Pelzeln, Kölliker, very justly, attaches no weight. "4. A tendency of organisms to give rise to useful varieties, and a natural selection, do not exist. "The varieties which are found arise in consequence of manifold external influences, and it is not obvious why they all, or partially, should be particularly useful. Each animal suffices for its own ends, is perfect of its kind, and needs no further development. Should, however, a variety be useful and even maintain itself, there is no obvious reason why it should change any further. The whole conception of the imperfection of organisms and the necessity of their becoming perfected is plainly the weakest side of Darwin's Theory, and a _pis aller_ (Nothbehelf) because Darwin could think of no other principle by which to explain the metamorphoses which, as I also believe, have occurred." Here again we must venture to dissent completely from Professor Kölliker's conception of Mr. Darwin's hypothesis. It appears to us to be one of the many peculiar merits of that hypothesis that it involves no belief in a necessary and continual progress of organisms. Again, Mr. Darwin, if we read him aright, assumes no special tendency of organisms to give rise to useful varieties, and knows nothing of needs of development, or necessity of perfection. What he says is, in substance: All organisms vary. It is in the highest degree improbable that any given variety should have exactly the same relations to surrounding conditions as the parent stock. In that case it is either better fitted (when the variation may be called useful), or worse fitted, to cope with them. If better, it will tend to supplant the parent stock; if worse, it will tend to be extinguished by the parent stock. If (as is hardly conceivable) the new variety is so perfectly adapted to the conditions that no improvement upon it is possible,--it will persist, because, though it does not cease to vary, the varieties will be inferior to itself. If, as is more probable, the new variety is by no means perfectly adapted to its conditions, but only fairly well adapted to them, it will persist, so long as none of the varieties which it throws off are better adapted than itself. On the other hand, as soon as it varies in a useful way, _i.e._ when the variation is such as to adapt it more perfectly to its conditions, the fresh variety will tend to supplant the former. So far from a gradual progress towards perfection forming any necessary part of the Darwinian creed, it appears to us that it is perfectly consistent with indefinite persistence in one state, or with a gradual retrogression. Suppose, for example, a return of the glacial epoch and a spread of polar climatal conditions over the whole globe. The operation of natural selection under these circumstances would tend, on the whole, to the weeding out of the higher organisms and the cherishing of the lower forms of life. Cryptogamic vegetation would have the advantage over Phanerogamic; _Hydrozoa_ over Corals; _Crustacea_ over _Insecta_, and _Amphipoda_ and _Isopoda_ over the higher _Crustacea;_ Cetaceans and Seals over the _Primates_; the civilisation of the Esquimaux over that of the European. "5. Pelzeln has also objected that if the later organisms have proceeded from the earlier, the whole developmental series, from the simplest to the highest, could not now exist; in such a case the simpler organisms must have disappeared." To this Professor Kölliker replies, with perfect justice, that the conclusion drawn by Pelzeln does not really follow from Darwin's premises, and that, if we take the facts of Paleontology as they stand, they rather support than oppose Darwin's theory. "6. Great weight must be attached to the objection brought forward by Huxley, otherwise a warm supporter of Darwin's hypothesis, that we know of no varieties which are sterile with one another, as is the rule among sharply distinguished animal forms. "If Darwin is right, it must be demonstrated that forms may be produced by selection, which, like the present sharply distinguished animal forms, are infertile, when coupled with one another, and this has not been done." The weight of this objection is obvious; but our ignorance of the conditions of fertility and sterility, the want of carefully conducted experiments extending over long series of years, and the strange anomalies presented by the results of the cross-fertilisation of many plants, should all, as Mr. Darwin has urged, be taken into account in considering it. The seventh objection is that we have already discussed (_supra_ p. 82). The eighth and last stands as follows:-- "8. The developmental theory of Darwin is not needed to enable us to understand the regular harmonious progress of the complete series of organic forms from the simpler to the more perfect. "The existence of general laws of Nature explains this harmony, even if we assume that all beings have arisen separately and independent of one another. Darwin forgets that inorganic nature, in which there can be no thought of genetic connexion of forms, exhibits the same regular plan, the same harmony, as the organic world; and that, to cite only one example, there is as much a natural system of minerals as of plants and animals." We do not feel quite sure that we seize Professor Kölliker's meaning here, but he appears to suggest that the observation of the general order and harmony which pervade inorganic nature, would lead us to anticipate a similar order and harmony in the organic world. And this is no doubt true, but it by no means follows that the particular order and harmony observed among them should be that which we see. Surely the stripes of dun horses, and the teeth of the _foetal_ _Balæna_, are not explained by the "existence of General laws of Nature." Mr. Darwin endeavours to explain the exact order of organic nature which exists; not the mere fact that there is some order. And with regard to the existence of a natural system of minerals; the obvious reply is that there may be a natural classification of any objects--of stones on a sea-beach, or of works of art; a natural classification being simply an assemblage of objects in groups, so as to express their most important and fundamental resemblances and differences. No doubt Mr. Darwin believes that those resemblances and differences upon which our natural systems or classifications of animals and plants are based, are resemblances and differences which have been produced genetically, but we can discover no reason for supposing that he denies the existence of natural classifications of other kinds. And, after all, is it quite so certain that a genetic relation may not underlie the classification of minerals? The inorganic world has not always been what we see it. It has certainly had its metamorphoses, and, very probably, a long "Entwickelungsgeschichte" out of a nebular blastema. Who knows how far that amount of likeness among sets of minerals, in virtue of which they are now grouped into families and orders, may not be the expression of the common conditions to which that particular patch of nebulous fog, which may have been constituted by their atoms, and of which they may be, in the strictest sense, the descendants, was subjected? It will be obvious from what has preceded, that we do not agree with Professor Kölliker in thinking the objections which he brings forward so weighty as to be fatal to Darwin's view. But even if the case were otherwise, we should be unable to accept the "Theory of Heterogeneous Generation" which is offered as a substitute. That theory is thus stated:-- "The fundamental conception of this hypothesis is, that, under the influence of a general law of development, the germs of organisms produce others different from themselves. This might happen (1) by the fecundated ova passing, in the course of their development, under particular circumstances, into higher forms; (2) by the primitive and later organisms producing other organisms without fecundation, out of germs or eggs (Parthenogenesis)." In favour of this hypothesis, Professor Kölliker adduces the well-known facts of Agamogenesis, or "alternate generation"; the extreme dissimilarity of the males and females of many animals; and of the males, females, and neuters of those insects which live in colonies: and he defines its relations to the Darwinian theory as follows:-- "It is obvious that my hypothesis is apparently very similar to Darwin's, inasmuch as I also consider that the various forms of animals have proceeded directly from one another. My hypothesis of the creation of organisms by heterogeneous generation, however, is distinguished very essentially from Darwin's by the entire absence of the principle of useful variations and their natural selection: and my fundamental conception is this, that a great plan of development lies at the foundation of the origin of the whole organic world, impelling the simpler forms to more and more complex developments. How this law operates, what influences determine the development of the eggs and germs, and impel them to assume constantly new forms, I naturally cannot pretend to say; but I can at least adduce the great analogy of the alternation of generations. If a _Bipinnaria_, a _Brachiolaria_, a _Pluteus_, is competent to produce the Echinoderm, which is so widely different from it; if a hydroid polype can produce the higher Medusa; if the vermiform Trematode 'nurse' can develop within itself the very unlike _Cercaria_, it will not appear impossible that the egg, or ciliated embryo, of a sponge, for once, under special conditions, might become a hydroid polype, or the embryo of a Medusa, an Echinoderm." It is obvious, from, these extracts, that Professor Kölliker's hypothesis is based upon the supposed existence of a close analogy between the phænomena of Agamogenesis and the production of new species from pre-existing ones. But is the analogy a real one? We think that it is not, and, by the hypothesis cannot be. For what are the phænomena of Agamogenesis, stated generally? An impregnated egg develops into a sexless form, A; this gives rise, non-sexually, to a second form or forms, B, more or less different from A. B may multiply non-sexually again; in the simpler cases, however, it does not, but, acquiring sexual characters, produces impregnated eggs from whence A, once more, arises. No case of Agamogenesis is known in which _when A differs widely from B_, it is itself capable of sexual propagation. No case whatever is known in which the progeny of B, by sexual generation, is other than a reproduction of A. But if this be a true statement of the nature of the process of Agamogenesis, how can it enable us to comprehend the production of new species from already existing ones? Let us suppose Hyænas to have preceded Dogs, and to have produced the latter in this way. Then the Hyæna will represent A, and the Dog, B. The first difficulty that presents itself is that the Hyæna must be non-sexual, or the process will be wholly without analogy in the world of Agamogenesis. But passing over this difficulty, and supposing a male and female Dog to be produced at the same time from the Hyæna stock, the progeny of the pair, if the analogy of the simpler kinds of Agamogenesis [Footnote: If, on the contrary, we follow the analogy of the more complex forms of Agamogenesis, such as that exhibited by some _Trematoda_ and by the _Aphides_, the Hyæna must produce, non-sexually, a brood of sexless Dogs, from which other sexless Dogs must proceed. At the end of a certain number of terms of the series, the Dogs would acquire sexes and generate young; but these young would be, not Dogs, but Hyænas. In fact, we have demonstrated, in Agamogenetic phænomena, that inevitable recurrence to the original type, which is asserted to be true of variations in general, by Mr. Darwin's opponents; and which, if the assertion could be changed into a demonstration, would, in fact, be fatal to his hypothesis.] is to be followed, should be a litter, not of puppies, but of young Hyænas. For the Agamogenetic series is always, as we have seen, A:B:A:B, &c.; whereas, for the production of a new species, the series must be A:B:B:B, &c. The production of new species, or genera, is the extreme permanent divergence from the primitive stock. All known Agamogenetic processes, on the other hand, end in a complete return to the primitive stock. How then is the production of new species to be rendered intelligible by the analogy of Agamogenesis? The other alternative put by Professor Kölliker--the passage of fecundated ova in the course of their development into higher forms--would, if it occurred, be merely an extreme case of variation in the Darwinian sense, greater in degree than, but perfectly similar in kind to, that which occurred when the well-known Ancon Ram was developed from an ordinary Ewe's ovum. Indeed we have always thought that Mr. Darwin has unnecessarily hampered himself by adhering so strictly to his favourite "Natura non facit saltum." We greatly suspect that she does make considerable jumps in the way of variation now and then, and that these saltations give rise to some of the gaps which appear to exist in the series of known forms. Strongly and freely as we have ventured to disagree with Professor Kölliker, we have always done so with regret, and we trust without violating that respect which is due, not only to his scientific eminence and to the careful study which he has devoted to the subject, but to the perfect fairness of his argumentation, and the generous appreciation of the worth of Mr. Darwin's labours which he always displays. It would be satisfactory to be able to say as much for M. Flourens. But the Perpetual Secretary of the French Academy of Sciences deals with Mr. Darwin as the first Napoleon would have treated an "idéologue;" and while displaying a painful weakness of logic and shallowness of information, assumes a tone of authority, which always touches upon the ludicrous, and sometimes passes the limits of good breeding. For example (p. 56):-- "M. Darwin continue: 'Aucune distinction absolue n'a été et ne peut être établie entre les espèces et les variétés.' Je vous ai déjà dit que vous vous trompiez; une distinction absolue sépare les variétés d'avec les espèces." "_Je vous ai déjà dit_; moi, M. le Secrétaire perpétuel de l'Académie des Sciences: et vous "'Qui n'êtes rien, Pas même Académicien;' what do you mean by asserting the contrary?" Being devoid of the blessings of an Academy in England, we are unaccustomed to see our ablest men treated in this fashion, even by a "Perpetual Secretary." Or again, considering that if there is any one quality of Mr. Darwin's work to which friends and foes have alike borne witness, it is his candour and fairness in admitting and discussing objections, what is to be thought of M. Flourens' assertion, that "M. Darwin ne cite que les auteurs qui partagent ses opinions." (P. 40.) Once more (p. 65):-- "Enfin l'ouvrage de M. Darwin a paru. On ne peut qu'être frappé du talent de l'auteur. Mais quo d'idées obscures, que d'idées fausses! Quel jargon métaphysique jeté mal à propos dans l'histoire naturelle, qui tombe dans le galimatias dès qu'elle sort des idées claires, des idées justes! Quel langage prétentieux et vide! Quelles personnifications puériles et surannées! O lucidité! 0 solidité de l'esprit Français, que devenez-vous?" "Obscure ideas," "metaphysical jargon," "pretentious and empty language," "puerile and superannuated personifications." Mr. Darwin has many and hot opponents on this side of the Channel and in Germany, but we do not recollect to have found precisely these sins in the long catalogue of those hitherto laid to his charge. It is worth while, therefore, to examine into these discoveries effected solely by the aid of the "lucidity and solidity" of the mind of M. Flourens. According to M. Flourens, Mr. Darwin's great error is that he has personified Nature (p. 10), and further that he has "imagined a natural selection: he imagines afterwards that this power of selecting (_pouvoir d'élire_) which he gives to Nature is similar to the power of man. These two suppositions admitted, nothing stops him: he plays with Nature as he likes, and makes her do all he pleases." (P. 6.) And this is the way M. Flourens extinguishes natural selection: "Voyons donc encore une fois, ce qu'il peut y avoir de fondé dans ce qu'on nomme _élection naturelle_. "_L'élection naturelle_ n'est sous un autre nom que la nature. Pour un être organisé, la nature n'est que l'organisation, ni plus ni moins. "Il faudra donc aussi personnifier _l'organisation,_ et dire que _l'organisation_ choisit _l'organisation. L'élection naturelle_ est cette _forme substantielle_ dont on jouait autrefois avec tant de facilité. Aristote disait que 'Si l'art de bâtir était dans le bois, cet art agirait comme la nature.' A la place de _l'art de bâtir_ M. Darwin met _l'élection naturelle,_ et c'est tout un: l'un n'est pas plus chimérique que l'autre." (P. 31.) And this is really all that M. Flourens can make of Natural Selection. We have given the original, in fear lest a translation should be regarded as a travesty; but with the original before the reader, we may try to analyse the passage. "For an organised being, Nature is only organisation, neither more nor less." Organised beings then have absolutely no relation to inorganic nature: a plant does not depend on soil or sunshine, climate, depth in the ocean, height above it; the quantity of saline matters in water have no influence upon animal life; the substitution of carbonic acid for oxygen in our atmosphere would hurt nobody! That these are absurdities no one should know better than M. Flourens; but they are logical deductions from the assertion just quoted, and from the further statement that natural selection means only that "organisation chooses and selects organisation." For if it be once admitted (what no sane man denies) that the chances of life of any given organism are increased by certain conditions (A) and diminished by their opposites (B), then it is mathematically certain that any change of conditions in the direction of (A) will exercise a selective influence in favour of that organism, tending to its increase and multiplication, while any change in the direction of (B) will exercise a selective influence against that organism, tending to its decrease and extinction. Or, on the other hand, conditions remaining the same, let a given organism vary (and no one doubts that they do vary) in two directions: into one form (_a_) better fitted to cope with these conditions than the original stock, and a second (_b_) less well adapted to them. Then it is no less certain that the conditions in question must exercise a selective influence in favour of (_a_) and against (_b_), so that (_a_) will tend to predominance, and (_b_) to extirpation. That M. Flourens should be unable to perceive the logical necessity of these simple arguments, which lie at the foundation of all Mr. Darwin's reasoning; that he should confound an irrefragable deduction from the observed relations of organisms to the conditions which lie around them, with a metaphysical "forme substantielle," or a chimerical personification of the powers of Nature, would be incredible, were it not that other passages of his work leave no room for doubt upon the subject. "On imagine une _élection naturelle_ que, pour plus de ménagement, on me dit être _inconsciente_, sans s'apercevoir que le contresens littéral est précisément là: _élection inconsciente_." (P. 52.) "J'ai déjà dit ce qu'il faut penser de _l'élection naturelle_. Ou _l'élection naturelle_ n'est rien, ou c'est la nature: mais la nature douée _d'élection_, mais la nature personnifiée: dernière erreur du dernier siècle: Le XIXe ne fait plus de personnifications." (P. 53.) M. Flourens cannot imagine an unconscious selection--it is for him a contradiction in terms. Did M. Flourens ever visit one of the prettiest watering-places of "la belle France," the Baie d'Arcachon? If so, he will probably have passed through the district of the Landes, and will have had an opportunity of observing the formation of "dunes" on a grand scale. What are these "dunes"? The winds and waves of the Bay of Biscay have not much consciousness, and yet they have with great care "selected," from among an infinity of masses of silex of all shapes and sizes, which have been submitted to their action, all the grains of sand below a certain size, and have heaped them by themselves over a great area. This sand has been "unconsciously selected" from amidst the gravel in which it first lay with as much precision as if man had "consciously selected" it by the aid of a sieve. Physical Geology is full of such selections--of the picking out of the soft from the hard, of the soluble from the insoluble, of the fusible from the infusible, by natural agencies to which we are certainly not in the habit of ascribing consciousness. But that which wind and sea are to a sandy beach, the sum of influences, which we term the "conditions of existence," is to living organisms. The weak are sifted out from the strong. A frosty night "selects" the hardy plants in a plantation from among the tender ones as effectually as if it were the wind, and they, the sand and pebbles, of our illustration; or, on the other hand, as if the intelligence of a gardener had been operative in cutting the weaker organisms down. The thistle, which has spread over the Pampas, to the destruction of native plants, has been more effectually "selected" by the unconscious operation of natural conditions than if a thousand agriculturists had spent their time in sowing it. It is one of Mr. Darwin's many great services to Biological science that he has demonstrated the significance of these facts. He has shown that given variation and given change of conditions the inevitable result is the exercise of such an influence upon organisms that one is helped and another is impeded; one tends to predominate, another to disappear; and thus the living world bears within itself, and is surrounded by, impulses towards incessant change. But the truths just stated are as certain as any other physical laws, quite independently of the truth, or falsehood, of the hypothesis which Mr. Darwin has based upon them; and that Mr. Flourens, missing the substance and grasping at a shadow, should be blind to the admirable exposition of them, which Mr. Darwin has given, and see nothing there but a "dernière erreur du dernier siècle"--a personification of Nature--leads us indeed to cry with him: "O lucidité! O solidité de l'esprit Français, que devenez-vous?" M. Flourens has, in fact, utterly failed to comprehend the first principles of the doctrine which he assails so rudely. His objections to details are of the old sort, so battered and hackneyed on this side of the Channel, that not even a Quarterly Reviewer could be induced to pick them up for the purpose of pelting Mr. Darwin over again. We have Cuvier and the mummies; M. Roulin and the domesticated animals of America; the difficulties presented by hybridism and by Palæontology; Darwinism a _rifacciamento_ of De Maillet and Lamarck; Darwinism a system without a commencement, and its author bound to believe in M. Pouchet, &c. &c. How one knows it all by heart, and with what relief one reads at p. 65-- "Je laisse M. Darwin!" But we cannot leave M. Flourens without calling our readers' attention to his wonderful tenth chapter, "De la Préexistence des Germes et de l'Epigénèse," which opens thus:-- "Spontaneous generation is only a chimaera. This point established, two hypotheses remain: that of _pre-existence_ and that of _epigenesis_. The one of these hypotheses has as little foundation as the other." (p. 163.) "The doctrine of _epigenesis_ is derived from Harvey: following by ocular inspection the development of the new being in the Windsor does, he saw each part appear successively, and taking the moment of _appearance_ for the moment of _formation_ he imagined _epigenesis_." (p. 165.) On the contrary, says M. Flourens (p. 167), "The new being is formed at a stroke (_tout d'un coup_), as a whole, instantaneously; it is not formed part by part, and at different times. It is formed at once at the single _individual_ moment at which the conjunction of the male and female elements takes place." It will be observed that M. Flourens uses language which cannot be mistaken. For him, the labours of Von Baer, of Rathke, of Coste, and their contemporaries and successors in Germany, France, and England, are non-existent: and, as Darwin "_imagina_" natural selection, so Harvey "_imagina_" that doctrine which gives him an even greater claim to the veneration of posterity than his better known discovery of the circulation of the blood. Language such as that we have quoted is, in fact, so preposterous, so utterly incompatible with anything but absolute ignorance of some of the best established facts, that we should have passed it over in silence had it not appeared to afford some clue to M. Flourens' unhesitating, _ à priori_, repudiation of all forms of the doctrine of progressive modification of living beings. He whose mind remains uninfluenced by an acquaintance with the phænomena of development, must indeed lack one of the chief motives towards the endeavour to trace a genetic relation between the different existing forms of life. Those who are ignorant of Geology, find no difficulty in believing that the world was made as it is; and the shepherd, untutored in history, sees no reason to regard the green mounds which indicate the site of a Roman camp as aught but part and parcel of the primæval hillside. So M. Flourens, who believes that embryos are formed "tout d'un coup," naturally finds no difficulty in conceiving that species came into existence in the same way. IV THE GENEALOGY OF ANIMALS [Footnote: _The Natural History of Creation_. By Dr. Ernst Haeckel. [_Natürliche Schöpfungs-Geschichte_.--Von Dr. Ernst Haeckel, Professor an der Universität Jena.] Berlin, 1868.] [1869] Considering that Germany now takes the lead of the world in scientific investigation, and particularly in biology, Mr. Darwin must be well pleased at the rapid spread of his views among some of the ablest and most laborious of German naturalists. Among these, Professor Haeckel, of Jena, is the Coryphæus. I know of no more solid and important contributions to biology in the past seven years than Haeckel's work on the "Radiolaria," and the researches of his distinguished colleague Gegenbaur, in vertebrate anatomy; while in Haeckel's "Generelle Morphologie" there is all the force, suggestiveness, and, what I may term the systematising power, of Oken, without his extravagance. The "Generelle Morphologie" is, in fact, an attempt to put the Doctrine of Evolution, so far as it applies to the living world, into a logical form; and to work out its practical applications to their final results. The work before, us, again, may be said to be an exposition of the "Generelle Morphologie" for an educated public, consisting, as it does, of the substance of a series of lectures delivered before a mixed audience at Jena, in the session 1867-8. "The Natural History of Creation,"--or, as Professor Haeckel admits it would have been better to call his work, "The History of the Development or Evolution of Nature,"--deals, in the first six lectures, with the general and historical aspects of the question and contains a very interesting and lucid account of the views of Linnæus, Cuvier, Agassiz, Goethe, Oken, Kant, Lamarck, Lyell, and Darwin, and of the historical filiation of these philosophers. The next six lectures are occupied by a well-digested statement of Mr. Darwin's views. The thirteenth lecture discusses two topics which are not touched by Mr. Darwin, namely, the origin of the present form of the solar system, and that of living matter. Full justice is done to Kant, as the originator of that "cosmic gas theory," as the Germans somewhat quaintly call it, which is commonly ascribed to Laplace. With respect to spontaneous generation, while admitting that there is no experimental evidence in its favour, Professor Haeckel denies the possibility of disproving it, and points out that the assumption that it has occurred is a necessary part of the doctrine of Evolution. The fourteenth lecture, on "Schöpfungs-Perioden und Schöpfungs-Urkunden," answers pretty much to the famous disquisition on the "Imperfection of the Geological Record" in the "Origin of Species." The following five lectures contain the most original matter of any, being devoted to "Phylogeny," or the working out of the details of the process of Evolution in the animal and vegetable kingdoms, so as to prove the line of descent of each group of living beings, and to furnish it with its proper genealogical tree, or "phylum." The last lecture considers objections and sums up the evidence in favour of biological Evolution. I shall best testify to my sense of the value of the work thus briefly analysed if I now proceed to note down some of the more important criticisms which have been suggested to me by its perusal. I. In more than one place, Professor Haeckel enlarges upon the service which the "Origin of Species" has done, in favouring what he terms the "causal or mechanical" view of living nature as opposed to the "teleological or vitalistic" view. And no doubt it is quite true that the doctrine of Evolution is the most formidable opponent of all the commoner and coarser forms of Teleology. But perhaps the most remarkable service to the philosophy of Biology rendered by Mr. Darwin is the reconciliation of Teleology and Morphology, and the explanation of the facts of both which his views offer. The Teleology which supposes that the eye, such as we see it in man or one of the higher _Vertebrata_, was made with the precise structure which it exhibits, for the purpose of enabling the animal which possesses it to see, has undoubtedly received its death-blow. Nevertheless it is necessary to remember that there is a wider Teleology, which is not touched by the doctrine of Evolution, but is actually based upon the fundamental proposition of Evolution. That proposition is, that the whole world, living and not living, in the result of the mutual interaction, according to definite laws, of the forces possessed by the molecules of which the primitive nebulosity of the universe was composed. If this be true, it is no less certain that the existing world lay, potentially, in the cosmic vapour; and that a sufficient intelligence could, from a knowledge of the properties of the molecules of that vapour, have predicted, say the state of the Fauna of Britain in 1869, with as much certainty as one can say what will happen to the vapour of the breath in a cold winter's day. Consider a kitchen clock, which ticks loudly, shows the hours, minutes, and seconds, strikes, cries "cuckoo!" and perhaps shows the phases of the moon. When the clock is wound up, all the phenomena which it exhibits are potentially contained in its mechanism, and a clever clockmaker could predict all it will do after an examination of its structure. If the evolution theory is correct, the molecular structure of the cosmic gas stands in the same relation to the phenomena of the world as the structure of the clock to its phenomena. Now let us suppose a death-watch, living in the clock-case, to be a learned and intelligent student of its works. He might say, "I find here nothing but matter and force and pure mechanism from beginning to end," and he would be quite right. But if he drew the conclusion that the clock was not contrived for a purpose, he would be quite wrong. On the other hand, imagine another death-watch of a different turn of mind. He, listening to the monotonous "tick! tick!" so exactly like his own, might arrive at the conclusion that the clock was itself a monstrous sort of death-watch, and that its final cause and purpose was to tick. How easy to point to the clear relation of the whole mechanism to the pendulum, to the fact that the one thing the clock did always and without intermission was to tick, and that all the rest of its phenomena were intermittent and subordinate to ticking! For all this, it is certain that kitchen clocks are not contrived for the purpose of making a ticking noise. Thus the teleological theorist would be as wrong as the mechanical theorist, among our death-watches; and, probably, the only death-watch who would be right would be the one who should maintain that the sole thing death-watches could be sure about was the nature of the clock-works and the way they move; and that the purpose of the clock lay wholly beyond the purview of beetle faculties. Substitute "cosmic vapour" for "clock," and "molecules" for "works," and the application of the argument is obvious. The teleological and the mechanical views of nature are not, necessarily, mutually exclusive. On the contrary, the more purely a mechanist the speculator is, the more firmly does he assume a primordial molecular arrangement, of which all the phenomena of the universe are the consequences; and the more completely is he thereby at the mercy of the teleologist, who can always defy him to disprove that this primordial molecular arrangement was not intended to evolve the phenomena of the universe. On the other hand, if the teleologist assert that this, that, or the other result of the working of any part of the mechanism of the universe is its purpose and final cause, the mechanist can always inquire how he knows that it is more than an unessential incident--the mere ticking of the clock, which he mistakes for its function. And there seems to be no reply to this inquiry, any more than to the further, not irrational, question, why trouble one's self about matters which are out of reach, when the working of the mechanism itself, which is of infinite practical importance, affords scope for all our energies? Professor Haeckel has invented a new and convenient name "Dysteleology," for the study of the "purposelessnesses" which are observable in living organisms--such as the multitudinous cases of rudimentary and apparently useless structures. I confess, however, that it has often appeared to me that the facts of Dysteleology cut two ways. If we are to assume, as evolutionists in general do, that useless organs atrophy, such cases as the existence of lateral rudiments of toes, in the foot of a horse, place us in a dilemma. For, either these rudiments are of no use to the animal, in which case, considering that the horse has existed in its present form since the Pliocene epoch, they surely ought to have disappeared; or they are of some use to the animal, in which case they are of no use as arguments against Teleology. A similar, but still stronger, argument may be based upon the existence of teats, and even functional mammary glands, in male mammals. Numerous cases of "Gynæcomasty," or functionally active breasts in men, are on record, though there is no mammalian species whatever in which the male normally suckles the young. Thus, there can be little doubt that the mammary gland was as apparently useless in the remotest male mammalian ancestor of man as in living men, and yet it has not disappeared. Is it then still profitable to the male organism to retain it? Possibly; but in that case its dysteleological value is gone. [Footnote: The recent discovery of the important part played by the Thyroid gland should be a warning to all speculators about useless organs. 1893.] II. Professor Haeckel looks upon the causes which have led to the present diversity of living nature as twofold. Living matter, he tells us, is urged by two impulses: a centripetal, which tends to preserve and transmit the specific form, and which he identifies with heredity; and a centrifugal, which results from the tendency of external conditions to modify the organism and effect its adaptation to themselves. The internal impulse is conservative, and tends to the preservation of specific, or individual, form; the external impulse is metamorphic, and tends to the modification of specific, or individual, form. In developing his views upon this subject, Professor Haeckel introduces qualifications which disarm some of the criticisms I should have been disposed to offer; but I think that his method of stating the case has the inconvenience of tending to leave out of sight the important fact--which is a cardinal point in the Darwinian hypothesis--that the tendency to vary, in a given organism, may have nothing to do with the external conditions to which that individual organism is exposed, but may depend wholly upon internal conditions. No one, I imagine, would dream of seeking for the cause of the development of the sixth finger and toe in the famous Maltese, in the direct influence of the external conditions of his life. I conceive that both hereditary transmission and adaptation need to be analysed into their constituent conditions by the further application of the doctrine of the Struggle for Existence. It is a probable hypothesis, that what the world is to organisms in general, each organism is to the molecules of which it is composed. Multitudes of these, having diverse tendencies, are competing with one another for opportunity to exist and multiply; and the organism, as a whole, is as much the product of the molecules which are victorious as the Fauna, or Flora, of a country is the product of the victorious organic beings in it. On this hypothesis, hereditary transmission is the result of the victory of particular molecules contained in the impregnated germ. Adaptation to conditions is the result of the favouring of the multiplication of those molecules whose organising tendencies are most in harmony with such conditions. In this view of the matter, conditions are not actively productive, but are passively permissive; they do not cause variation in any given direction, but they permit and favour a tendency in that direction which already exists. It is true that, in the long run, the origin of the organic molecules themselves, and of their tendencies, is to be sought in the external world; but if we carry our inquiries as far back as this, the distinction between internal and external impulses vanishes. On the other hand, if we confine ourselves to the consideration of a single organism, I think it must be admitted that the existence of an internal metamorphic tendency must be as distinctly recognised as that of an internal conservative tendency; and that the influence of conditions is mainly, if not wholly, the result of the extent to which they favour the one, or the other, of these tendencies. III. There is only one point upon which I fundamentally and entirely disagree with Professor Haeckel, but that is the very important one of his conception of geological time, and of the meaning of the stratified rocks as records and indications of that time. Conceiving that the stratified rocks of an epoch indicate a period of depression, and that the intervals between the epochs correspond with periods of elevation of which we have no record, he intercalates between the different epochs, or periods, intervals which he terms "Ante-periods." Thus, instead of considering the Triassic, Jurassic, Cretaceous, and Eocene periods, as continuously successive, he interposes a period before each, as an "Antetrias-zeit," "Antejura-zeit," "Antecreta-zeit," "Anteo-cenzeit," &c. And he conceives that the abrupt changes between the Faunæ of the different formations are due to the lapse of time, of which we have no organic record, during their "Ante-periods." The frequent occurrence of strata containing assemblages of organic forms which are intermediate between those of adjacent formations, is, to my mind, fatal to this view. In the well-known St. Cassian beds, for example, Palaeozoic and Mesozoic forms are commingled, and, between the Cretaceous and the Eocene formations, there are similar transitional beds. On the other hand, in the middle of the Silurian series, extensive unconformity of the strata indicates the lapse of vast intervals of time between the deposit of successive beds, without any corresponding change in the Fauna. Professor Haeckel will, I fear, think me unreasonable, if I say that he seems to be still overshadowed by geological superstitions; and that he will have to believe in the completeness of the geological record far less than he does at present. He assumes, for example, that there was no dry land, nor any terrestrial life, before the end of the Silurian epoch, simply because, up to the present time, no indications of fresh water, or terrestrial organisms, have been found in rocks of older date. And, in speculating upon the origin of a given group, he rarely goes further back than the "Ante-period," which precedes that in which the remains of animals belonging to that group are found. Thus, as fossil remains of the majority of the groups of _Reptilia_ are first found in the Trias, they are assumed to have originated in the "Antetriassic" period, or between the Permian and Triassic epochs. I confess this is wholly incredible to me. The Permian and the Triassic deposits pass completely into one another; there is no sort of discontinuity answering to an unrecorded "Antetrias"; and, what is more, we have evidence of immensely extensive dry land during the formation of these deposits. We know that the dry land of the Trias absolutely teemed with reptiles of all groups except Pterodactyles, Snakes, and perhaps Tortoises; there is every probability that true Birds existed, and _Mammalia_ certainly did. Of the inhabitants of the Permian dry land, on the contrary, all that have left a record are a few lizards. Is it conceivable that these last should really represent the whole terrestrial population of that time, and that the development of Mammals, of Birds, and of the highest forms of Reptiles, should have been crowded into the time during which the Permian conditions quietly passed away, and the Triassic conditions began? Does not any such supposition become in the highest degree improbable, when, in the terrestrial or fresh-water Labyrinthodonts, which lived on the land of the Carboniferous epoch, as well as on that of the Trias, we have evidence that one form of terrestrial life persisted, throughout all these ages, with no important modification? For my part, having regard to the small amount of modification (except in the way of extinction) which the Crocodilian, Lacertilian, and Chelonian _Reptilia_ have undergone, from the older Mesozoic times to the present day, I cannot but put the existence of the common stock from which they sprang far back in the Palæozoic epoch; and I should apply a similar argumentation to all other groups of animals. [The remainder of this essay contains a discussion of questions of taxonomy and phylogeny, which is now antiquated. I have reprinted the considerations about the reconciliation of Teleology with Morphology, about "Dysteleology," and about the struggle for existence within the organism, because it has happened to me to be charged with overlooking them. In discussing Teleology, I ought to have pointed out, as I have done elsewhere (_Life and Letters of Charles Darwin_, vol. ii. p. 202), that Paley "proleptically accepted the modern doctrine of Evolution," (_Natural Theology_, chap. xxiii.). 1893.] V MR. DARWIN'S CRITICS [Footnote: _Contributions to the Theory of Natural Selection_. By A. R. Wallace. 1870.--2. _The Genesis of Species_. By St. George Mivart, F.R.S. Second Edition. 1871.--3. _Darwin's Descent of Man_. Quarterly Review, July 1871.] [1871] The gradual lapse of time has now separated us by more than a decade from the date of the publication of the "Origin of Species"--and whatever may be thought or said about Mr. Darwin's doctrines, or the manner in which he has propounded them, this much is certain, that, in a dozen years, the "Origin of Species" has worked as complete a revolution in biological science as the "Principia" did in astronomy--and it has done so, because, in the words of Helmholtz, it contains "an essentially new creative thought." [Footnote: Helmholtz: _Ueber das Ziel und die Fortschritte der Naturwissenschaft_. Eröffnungsrede für die Naturforscherversammlung zu Innsbruck. 1869.] And as time has slipped by, a happy change has come over Mr. Darwin's critics. The mixture of ignorance and insolence which, at first, characterised a large proportion of the attacks with which he was assailed, is no longer the sad distinction of anti-Darwinian criticism. Instead of abusive nonsense, which merely discredited its writers, we read essays, which are, at worst, more or less intelligent and appreciative; while, sometimes, like that which appeared in the "North British Review" for 1867, they have a real and permanent value. The several publications of Mr. Wallace and Mr. Mivart contain discussions of some of Mr. Darwin's views, which are worthy of particular attention, not only on account of the acknowledged scientific competence of these writers, but because they exhibit an attention to those philosophical questions which underlie all physical science, which is as rare as it is needful. And the same may be said of an article in the "Quarterly Review" for July 1871, the comparison of which with an article in the same Review for July 1860, is perhaps the best evidence which can be brought forward of the change which has taken place in public opinion on "Darwinism." The Quarterly Reviewer admits "the certainty of the action of natural selection" (p. 49); and further allows that there is an _à priori_ probability in favour of the evolution of man from some lower animal form, if these lower animal forms themselves have arisen by evolution. Mr. Wallace and Mr. Mivart go much further than this. They are as stout believers in evolution as Mr. Darwin himself; but Mr. Wallace denies that man can have been evolved from a lower animal by that process of natural selection which he, with Mr. Darwin, holds to have been sufficient for the evolution of all animals below man; while Mr. Mivart, admitting that natural selection has been one of the conditions of the evolution of the animals below man, maintains that natural selection must, even in their case, have been supplemented by "some other cause"--of the nature of which, unfortunately, he does not give us any idea. Thus Mr. Mivart is less of a Darwinian than Mr. Wallace, for he has less faith in the power of natural selection. But he is more of an evolutionist than Mr. Wallace, because Mr. Wallace thinks it necessary to call in an intelligent agent--a sort of supernatural Sir John Sebright--to produce even the animal frame of man; while Mr. Mivart requires no Divine assistance till he comes to man's soul. Thus there is a considerable divergence between Mr. Wallace and Mr. Mivart. On the other hand, there are some curious similarities between Mr. Mivart and the Quarterly Reviewer, and these are sometimes so close, that, if Mr. Mivart thought it worth while, I think he might make out a good case of plagiarism against the Reviewer, who studiously abstains from quoting him. Both the Reviewer and Mr. Mivart reproach Mr. Darwin with being, "like so many other physicists," entangled in a radically false metaphysical system, and with setting at nought the first principles of both philosophy and religion. Both enlarge upon the necessity of a sound philosophical basis, and both, I venture to add, make a conspicuous exhibition of its absence. The Quarterly Reviewer believes that man "differs more from an elephant or a gorilla than do these from the dust of the earth on which they tread," and Mr. Mivart has expressed the opinion that there is more difference between man and an ape than there is between an ape and a piece of granite. [Footnote: See the _Tablet_ for March 11, 1871.] And even when Mr. Mivart (p. 86) trips in a matter of anatomy, and creates a difficulty for Mr. Darwin out of a supposed close similarity between the eyes of fishes and cephalopods, which (as Gegenbaur and others have clearly shown) does not exist, the Quarterly Reviewer adopts the argument without hesitation (p. 66). There is another important point, however, in which it is hard to say whether Mr. Mivart diverges from the Quarterly Reviewer or not. The Reviewer declares that Mr. Darwin has, "with needless opposition, set at nought the first principles of both philosophy and religion" (p. 90). It looks, at first, as if this meant, that Mr. Darwin's views being false, the opposition to "religion" which flows from them must be needless. But I suspect this is not the right view of the meaning of the passage, as Mr. Mivart, from whom the Quarterly Reviewer plainly draws so much inspiration, tells us that "the consequences which have been drawn from evolution, whether exclusively Darwinian or not, to the prejudice of religion, by no means follow from it, and are in fact illegitimate" (p. 5). I may assume, then, that the Quarterly Reviewer and Mr. Mivart admit that there is no necessary opposition between "evolution whether exclusively Darwinian or not," and religion. But then, what do they mean by this last much-abused term? On this point the Quarterly Reviewer is silent. Mr. Mivart, on the contrary, is perfectly explicit, and the whole tenor of his remarks leaves no doubt that by "religion" he means theology; and by theology, that particular variety of the great Proteus, which is expounded by the doctors of the Roman Catholic Church, and held by the members of that religious community to be the sole form of absolute truth and of saving faith. According to Mr. Mivart, the greatest and most orthodox authorities upon matters of Catholic doctrine agree in distinctly asserting "derivative creation" or evolution; "and thus their teachings harmonise with all that modern science can possibly require" (p. 305). I confess that this bold assertion interested me more than anything else in Mr. Mivart's book. What little knowledge I possessed of Catholic doctrine, and of the influence exerted by Catholic authority in former times, had not led me to expect that modern science was likely to find a warm welcome within the pale of the greatest and most consistent of theological organisations. And my astonishment reached its climax when I found Mr. Mivart citing Father Suarez as his chief witness in favour of the scientific freedom enjoyed by Catholics--the popular repute of that learned theologian and subtle casuist not being such as to make his works a likely place of refuge for liberality of thought. But in these days, when Judas Iscariot and Robespierre, Henry VIII. and Catiline, have all been shown to be men of admirable virtue, far in advance of their age, and consequently the victims of vulgar prejudice, it was obviously possible that Jesuit Suarez might be in like case. And, spurred by Mr. Mivart's unhesitating declaration, I hastened to acquaint myself with such of the works of the great Catholic divine as bore upon the question, hoping, not merely to acquaint myself with the true teachings of the infallible Church, and free myself of an unjust prejudice; but, haply, to enable myself, at a pinch, to put some Protestant bibliolater to shame, by the bright example of Catholic freedom from the trammels of verbal inspiration. I regret to say that my anticipations have been cruelly disappointed. But the extent to which my hopes have been crushed can only be fully appreciated by citing, in the first place, those passages of Mr. Mivart's work by which they were excited. In his introductory chapter I find the following passages:-- "The prevalence of this theory [of evolution] need alarm no one, for it is, without any doubt, perfectly consistent with the strictest and most orthodox Christian [Footnote: It should be observed that Mr. Mivart employs the term 'Christian' as if it were the equivalent of 'Catholic.'] theology" (p. 5). "Mr. Darwin and others may perhaps be excused if they have not devoted much time to the study of Christian philosophy; but they have no right to assume or accept without careful examination, as an unquestioned fact, that in that philosophy there is a necessary antagonism between the two ideas 'creation' and 'evolution,' as applied to organic forms. "It is notorious and patent to all who choose to seek, that many distinguished Christian thinkers have accepted, and do accept, both ideas, _i.e._ both 'creation' and 'evolution.' "As much as ten years ago an eminently Christian writer observed: 'The creationist theory does not necessitate the perpetual search after manifestations of miraculous power and perpetual "catastrophes." Creation is not a miraculous interference with the laws of Nature, but the very institution of those laws. Law and regularity, not arbitrary intervention, was the patristic ideal of creation. With this notion they admitted, without difficulty, the most surprising origin of living creatures, provided it took place by _law_. They held that when God said, "Let the waters produce," "Let the earth produce," He conferred forces on the elements of earth and water which enabled them naturally to produce the various species of organic beings. This power, they thought, remains attached to the elements throughout all time.' The same writer quotes St. Augustin and St. Thomas Aquinas, to the effect that, 'in the institution of Nature, we do not look for miracles, but for the laws of Nature.' And, again, St. Basil speaks of the continued operation of natural laws in the production of all organisms. "So much for the writers of early and mediæval times. As to the present day, the author can confidently affirm that there are many as well versed in theology as Mr. Darwin is in his own department of natural knowledge, who would not be disturbed by the thorough demonstration of his theory. Nay, they would not even be in the least painfully affected at witnessing the generation of animals of complex organisation by the skilful artificial arrangement of natural forces, and the production, in the future, of a fish by means analogous to those by which we now produce urea. "And this because they know that the possibility of such phenomena, though by no means actually foreseen, has yet been fully provided for in the old philosophy centuries before Darwin, or even centuries before Bacon, and that their place in the system can be at once assigned them without even disturbing its order or marring its harmony. "Moreover, the old tradition in this respect has never been abandoned, however much it may have been ignored or neglected by some modern writers. In proof of this, it may be observed that perhaps no post-mediæval theologian has a wider reception amongst Christians throughout the world than Suarez, who has a separate section [Footnote: Suarez, _Metaphysica_. Edition Vivés. Paris, 1868, vol. i Disput. xv. § 2.] in opposition to those who maintain the distinct creation of the various kinds--or substantial forms--of organic life" (pp. 19-21). Still more distinctly does Mr. Mivart express himself in the same sense, in his last chapter, entitled "Theology and Evolution" (pp. 302-5). "It appears, then, that Christian thinkers are perfectly free to accept the general evolution theory. But are there any theological authorities to justify this view of the matter? "Now, considering how extremely recent are these biological speculations, it might hardly be expected _à priori_ that writers of earlier ages should have given expression to doctrines harmonising in any degree with such very modern views; nevertheless, this is certainly the case, and it would be easy to give numerous examples. It will be better, however, to cite one or two authorities of weight. Perhaps no writer of the earlier Christian ages could be quoted whose authority is more generally recognised than that of St. Augustin. The same may be said of the mediæval period for St. Thomas Aquinas: and since the movement of Luther, Suarez may be taken as an authority, widely venerated, and one whose orthodoxy has never been questioned. "It must be borne in mind that for a considerable time even after the last of these writers no one had disputed the generally received belief as to the small age of the world, or at least of the kinds of animals and plants inhabiting it. It becomes, therefore, much more striking if views formed under such a condition of opinion are found to harmonise with modern ideas concerning 'Creation' and organic Life. "Now St. Augustin insists in a very remarkable manner on the merely derivative sense in which God's creation of organic forms is to be understood; that is, that God created them by conferring on the material world the power to evolve them under suitable conditions." Mr. Mivart then cites certain passages from St. Augustin, St. Thomas Aquinas, and Cornelius à Lapide, and finally adds:-- "As to Suarez, it will be enough to refer to Disp. xv. sec. 2, No. 9, p. 508, t. i. edition Vivés, Paris; also Nos. 13-15. Many other references to the same effect could easily be given, but these may suffice. "It is then evident that ancient and most venerable theological authorities distinctly assert derivative creation, and thus their teachings harmonise with all that modern science can possibly require." It will be observed that Mr. Mivart refers solely to Suarez's fifteenth Disputation, though he adds, "Many other references to the same effect could easily be given." I shall look anxiously for these references in the third edition of the "Genesis of Species." For the present, all I can say is, that I have sought in vain, either in the fifteenth Disputation, or elsewhere, for any passage in Suarez's writings which, in the slightest degree, bears out Mr. Mivart's views as to his opinions. [Footnote: The edition of Suarez's _Disputationes_ from which the following citations are given, is Birckmann's, in two volumes folio, and is dated 1680.] The title of this fifteenth Disputation is "De causa formali substantiali," and the second section of that Disputation (to which Mr. Mivart refers) is headed, "Quomodo possit forma substantialis fieri in materia et ex materia?" The problem which Suarez discusses in this place may be popularly stated thus: According to the scholastic philosophy every natural body has two components--the one its "matter" (_materia prima_), the other its "substantial form" (_forma substantialis_). Of these the matter is everywhere the same, the matter of one body being indistinguishable from the matter of any other body. That which differentiates any one natural body from all others is its substantial form, which inheres in the matter of that body, as the human soul inheres in the matter of the frame of man, and is the source of all the activities and other properties of the body. Thus, says Suarez, if water is heated, and the source of heat is then removed, it cools again. The reason of this is that there is a certain "_intimius principium_" in the water, which brings it back to the cool condition when the external impediment to the existence of that condition is removed. This _intimius principium_ is the "substantial form" of the water. And the substantial form of the water is not only the cause (_radix_) of the coolness of the water, but also of its moisture, of its density, and of all its other properties. It will thus be seen that "substantial forms" play nearly the same part in the scholastic philosophy as "forces" do in modern science; the general tendency of modern thought being to conceive all bodies as resolvable into material particles and forces, in virtue of which last these particles assume those dispositions and exercise those powers which are characteristic of each particular kind of matter. But the Schoolmen distinguished two kinds of substantial forms, the one spiritual and the other material. The former division is represented by the human soul, the _anima rationalis_; and they affirm as a matter, not merely of reason, but of faith, that every human soul is created out of nothing, and by this act of creation is endowed with the power of existing for all eternity, apart from the _materia prima_ of which the corporeal frame of man is composed. And the _anima rationalis_, once united with the _materia prima_ of the body, becomes its substantial form, and is the source of all the powers and faculties of man--of all the vital and sensitive phenomena which he exhibits--just as the substantial form of water is the source of all its qualities. The "material substantial forms" are those which inform all other natural bodies except that of man; and the object of Suarez in the present Disputation, is to show that the axiom "_ex nihilo nihil fit_," though not true of the substantial form of man, is true of the substantial forms of all other bodies, the endless mutations of which constitute the ordinary course of nature. The origin of the difficulty which he discusses is easily comprehensible. Suppose a piece of bright iron to be exposed to the air. The existence of the iron depends on the presence within it of a substantial form, which is the cause of its properties, _e.g._ brightness, hardness, weight. But, by degrees, the iron becomes converted into a mass of rust, which is dull, and soft, and light, and, in all other respects, is quite different from the iron. As, in the scholastic view, this difference is due to the rust being informed by a new substantial form, the grave problem arises, how did this new substantial form come into being? Has it been created? or has it arisen by the power of natural causation? If the former hypothesis is correct, then the axiom, "_ex nihilo nihil fit_," is false, even in relation to the ordinary course of nature, seeing that such mutations of matter as imply the continual origin of new substantial forms are occurring every moment. But the harmonisation of Aristotle with theology was as dear to the Schoolmen, as the smoothing down the differences between Moses and science is to our Broad Churchmen, and they were proportionably unwilling to contradict one of Aristotle's fundamental propositions. Nor was their objection to flying in the face of the Stagirite likely to be lessened by the fact that such flight landed them in flat Pantheism. So Father Suarez fights stoutly for the second hypothesis; and I quote the principal part of his argumentation as an exquisite specimen of that speech which is a "darkening of counsel." "13. Secundo de omnibus aliis formis substantialibus [sc. materialibus] dicendum est non fieri proprie ex nihilo, sed ex potentia præjacentis materiæ educi: ideoque in effectione harum formarum nil fieri contra illud axioma, _Ex nihilo nihil fit_, si recte intelligatur. Hæc assertio sumitur ex Aristotele 1. Physicorum per totum et libro 7. Metaphyss. et ex aliis auctoribus, quos statim referam. Et declaratur breviter, nam fieri ex nihilo duo dicit, unum est fieri absolute et simpliciter, aliud est quod talis effectio fit ex nihilo. Primum propriè dicitur de re subsistente, quia ejus est fieri, cujus est esse: id autem proprie quod subsistit et habet esse; nam quod alteri adjacet, potius est quo aliud est. Ex hac ergo parte, formæ substantiales materiales non fiunt ex nihilo, quia proprie non fiunt. Atque hanc rationem reddit Divus Thomas 1 parte, quæstione 45, articulo 8, et quæstione 90, articulo 2, et ex dicendis magis explicabitur. Sumendo ergo ipsum _fieri_ in hac proprietate et rigore, sic fieri ex nihilo est fieri secundum se totum, id est nulla sui parte præsupposita, ex quo fiat. Et hac ratione res naturales dum de novo fiunt, non fiunt ex nihilo, quia fiunt ex præsupposita materia, ex qua componuntur, et ita non fiunt, secundum se totæ, sed secundum aliquid sui. Formæ autem harum rerum, quamvis revera totam suam entitatem de novo accipiant, quam antea non habebant, quia vero ipsæ non fiunt, ut dictum est, ideo neque ex nihilo fiunt. Attamen, quia latiori modo sumendo verbum illud _fieri_ negari non potest: quin forma facta sit, eo modo quo nunc est, et antea non erat, ut etiam probat ratio dubitandi posita in principio sectionis, ideo addendum est, sumpto _fieri_ in hac amplitudine, fieri ex nihilo non tamen negare habitudinem materialis causæ intrinsecè componentis id quod fit, sed etiam habitudinem causæ materialis per se causantis et sustentantis formam quæ fit, seu confit. Diximus enim in superioribus materiam et esse causam compositi et formæ dependentis ab illa: ut res ergo dicatur ex nihilo fieri uterque modus causalitatis negari debet; et eodem sensu accipiendum est illud axioma, ut sit verum: _Ex nihilo nihil fit_, scilicet virtute agentis naturalis et finiti nihil fieri, nisi ex præsupposito subjecto per se concurrente, et ad compositum et ad formam, si utrumque suo modo ab eodem agente fiat. Ex his ergo rectè concluditur, formas substantiales materiales non fieri ex nihilo, quia fiunt ex materia, quæ in suo genere per se concurrit, et influit ad esse, et fieri talium formarum; quia, sicut esse non possunt nisi affixae materiæ, a qua sustententur in esse: ita nec fieri possunt, nisi earum effectio et penetratio in eadem materia sustentetur. Et hæc est propria et per se differentia inter effectionem ex nihilo, et ex aliquo, propter quam, ut infra ostendemus, prior modus efficiendi superat vim finitam naturaliam agentium, non vero posterior. "14. Ex his etiam constat, proprie de his formis dici non creari, sed educi de potentia materiæ." [Footnote: Suarez, _loc. cit._ Disput. xv. § ii.] If I may venture to interpret these hard sayings, Suarez conceives that the evolution of substantial forms in the ordinary course of nature, is conditioned not only by the existence of the _materia prima_, but also by a certain "concurrence and influence" which that _materia_ exerts; and every new substantial form being thus conditioned, and in part, at any rate, caused, by a pre-existing something, cannot be said to be created out of nothing. But as the whole tenor of the context shows, Suarez applies this argumentation merely to the evolution of material substantial forms in the ordinary course of nature. How the substantial forms of animals and plants primarily originated, is a question to which, so far as I am able to discover, he does not so much as allude in his "Metaphysical Disputations." Nor was there any necessity that he should do so, inasmuch as he has devoted a separate treatise of considerable bulk to the discussion of all the problems which arise out of the account of the Creation which is given in the Book of Genesis. And it is a matter of wonderment to me that Mr. Mivart, who somewhat sharply reproves "Mr. Darwin and others" for not acquainting themselves with the true teachings of his Church, should allow himself to be indebted to a heretic like myself for a knowledge of the existence of that "Tractatus de opere sex Dierum," [Footnote: _Tractatus de opere sex Dierum, seu de Universi Creatione, quatenus sex diebus perfecta esse, in libro Genesis cap. i. refertur, et praesertim de productione hominis in statu innocentiae._ Ed. Birckmann, 1622.] in which the learned Father, of whom he justly speaks, as "an authority widely venerated, and whose orthodoxy has never been questioned," directly opposes all those opinions for which Mr. Mivart claims the shelter of his authority. In the tenth and eleventh chapters of the first book of this treatise, Suarez inquires in what sense the word "day," as employed in the first chapter of Genesis, is to be taken. He discusses the views of Philo and of Augustin on this question, and rejects them. He suggests that the approval of their allegorising interpretations by St. Thomas Aquinas, merely arose out of St. Thomas's modesty, and his desire not to seem openly to controvert St. Augustin--"voluisse Divus Thomas pro sua modestia subterfugere vim argumenti potius quam aperte Augustinum inconstantiæ arguere." Finally, Suarez decides that the writer of Genesis meant that the term "day" should be taken in its natural sense; and he winds up the discussion with the very just and natural remark that "it is not probable that God, in inspiring Moses to write a history of the Creation which was to be believed by ordinary people, would have made him use language, the true meaning of which it is hard to discover, and still harder to believe." [Footnote: "Propter hæc ergo sententia illa Augustini et propter nimiam obscuritatem et subtilitatem ejus difficilis creditu est: quia verisimile non est Deum inspirasse Moysi, ut historiam de creatione mundi ad fidem totius populi adeo necessariam per nomina dierum explicaret, quorum significatio vix inveniri et difficillime ab aliquo credi posset." (_Loc. cit._ Lib. I. cap. xi. 42.)] And in chapter xii. 3, Suarez further observes:-- "Ratio enim retinendi veram significationem diei naturalis est illa communis, quod verba Scripturæ non sunt ad metaphoras transferenda, nisi vel necessitas cogit, vel ex ipsa scriptura constet, et maximè in historica narratione et ad instructionem fidei pertinente: sed hæc ratio non minus cogit ad intelligendum propriè dierum numerum, quam diei qualitatem, QUIA NON MINUS UNO MODO QUAM ALIO DESTRUITUR SINCERITAS, IMO ET VERITAS HISTORIÆ. Secundo hoc valde confirmant alia Scripturæ loca, in quibus hi sex dies tanquam veri, et inter se distincti commemorantur, ut Exod. 20 dicitur, _Sex diebus operabis et facies omnia opera tua, septimo autem die Sabbatum Domini Dei tui est_. Et infra: _Sex enim diebus fecit Dominus cælum et terram et mare et omnia quæ in eis sunt_, et idem repetitur in cap. 31. In quibus locis sermonis proprietas colligi potest tum ex æquiparatione, nam cum dicitur: _sex diebus operabis_, propriissimè intelligitur: tum quia non est verisimile, potuisse populum intelligere verba illa in alio sensu, et è contrario incredibile est, Deum in suis præceptis tradendis illis verbis ad populum fuisse loquutum, quibus deciperetur, falsum sensum concipiendo, si Deus non per sex veros dies opera sua fecisset." These passages leave no doubt that this great doctor of the Catholic Church, of unchallenged authority and unspotted orthodoxy, not only declares it to be Catholic doctrine that the work of creation took place in the space of six natural days; but that he warmly repudiates, as inconsistent with our knowledge of the Divine attributes, the supposition that the language which Catholic faith requires the believer to hold that God inspired, was used in any other sense than that which He knew it would convey to the minds of those to whom it was addressed. And I think that in this repudiation Father Suarez will have the sympathy of every man of common uprightness, to whom it is certainly "incredible" that the Almighty should have acted in a manner which He would esteem dishonest and base in a man. But the belief that the universe was created in six natural days is hopelessly inconsistent with the doctrine of evolution, in so far as it applies to the stars and planetary bodies; and it can be made to agree with a belief in the evolution of living beings only by the supposition that the plants and animals, which are said to have been created on the third, fifth, and sixth days, were merely the primordial forms, or rudiments, out of which existing plants and animals have been evolved; so that, on these days, plants and animals were not created actually, but only potentially. The latter view is that held by Mr. Mivart, who follows St. Augustin, and implies that he has the sanction of Suarez. But, in point of fact, the latter great light of orthodoxy takes no small pains to give the most explicit and direct contradiction to all such imaginations, as the following passages prove. In the first place, as regards plants, Suarez discusses the problem:-- "_Quomodo herba virens et cætera vegetabilia hoc_ [_tertio_] _die fuerint producta_. [Footnote: _Loc. cit._ Lib. II. cap. vii. et viii. 1, 32, 35.] "Præcipua enim difficultas hîc est, quam attingit Div. Thomas 1, par. qu. 69, art. 2, an hæc productio plantarum hoc die facta intelligenda sit de productione ipsarum in proprio esse actuali et formali (ut sic rem explicerem) vel de productione tantum in semine et in potentia. Nam Divus Augustinus libro quinto Genes, ad liter. cap. 4 et 5 et libro 8, cap. 3, posteriorem partem tradit, dicens, terram in hoc die accepisse virtutem germinandi omnia vegetabilia quasi concepto omnium illorum semine, non tamen statim vegetabilia omnia produxisse. Quod primo suadet verbis illis capitis secundi. _In die quo fecit Deus cælum et terram et omne virgultum agri priusquam germinaret_. Quomodo enim potuerunt virgulta fieri antequam terra germinaret nisi quia causaliter prius et quasi in radice, seu in semine facta sunt, et postea in actu producta? Secundo confirmari potest, quia verbum illud _germinet terra_ optimè exponitur potestativè ut sic dicam, id est accipiat terra vim germinandi. Sicut in eodem capite dicitur _crescite et multiplicamini_. Tertio potest confirmari, quia actualis productio vegetabilium non tam ad opus creationis, quam ad opus propagationis pertinet, quod postea factum est. Et hanc sententiam sequitur Eucherius lib. 1, in Gen. cap. 11, et illi faveat Glossa, interli. Hugo. et Lyran. dum verbum _germinet_ dicto modo exponunt. NIHILOMINUS CONTRARIA SENTENTIA TENENDA EST: SCILICET, PRODUXISSE DEUM HOC DIE HERBAM, ARBORES, ET ALIA VEGETABILIA ACTU IN PROPRIA SPECIE ET NATURA. Hæc est communis sententia Patrum.--Basil. homil. 5; Exæmer. Ambros. lib. 3; Exæmer. cap. 8, 11, et 16; Chrysost. homil. 5 in Gen. Damascene. lib. 2 de Fid. cap. 10; Theodor. Cyrilli. Bedæ, Glossæ ordinariæ et aliorum in Gen. Et idem sentit Divus Thomas, _supra_, solvens argumenta Augustini, quamvis propter reverentiam ejus quasi problematicè semper procedat. Denique idem sentiunt omnes qui in his operibus veram successionem et temporalem distinctionem agnoscant." Secondly, with respect to animals, Suarez is no less decided:-- "_De animalium ratione carentium productione quinto et sexto die facta_. [Footnote: _Loc. cit_. Lib. II. cap. vii. et viii. 1, 32, 35.] "32. Primo ergo nobis certum sit hæc animantia non in virtute tantum aut in semine, sed actu, et in seipsis, facta fuisse his diebus in quibus facta narrantur. Quanquam Augustinus lib. 3, Gen. ad liter, cap. 5 in sua persistens sententia contrarium sentire videatur." But Suarez proceeds to refute Augustin's opinions at great length, and his final judgment may be gathered from the following passage:-- "35. Tertio dicendum est, hæc animalia omnia his diebus producta esse, IN PERFECTO STATU, IN SINGULIS INDIVIDUIS, SEU SPECIEBUS SUIS, JUXTA UNIUSCUJUSQUE NATURAM.... ITAQUE FUERUNT OMNIA CREATA INTEGRA ET OMNIBUS SUIS MEMBRIS PERFECTA." As regards the creation of animals and plants, therefore, it is clear that Suarez, so far from "distinctly asserting derivative creating," denies it as distinctly and positively as he can; that he is at much pains to refute St. Augustin's opinions; that he does not hesitate to regard the faint acquiescence of St. Thomas Aquinas in the views of his brother saint as a kindly subterfuge on the part of Divus Thomas; and that he affirms his own view to be that which is supported by the authority of the Fathers of the Church. So that, when Mr. Mivart tells us that Catholic theology is in harmony with all that modern science can possibly require; that "to the general theory of evolution, and to the special Darwinian form of it, no exception ... need be taken on the ground of orthodoxy;" and that "law and regularity, not arbitrary intervention, was the Patristic ideal of creation," we have to choose between his dictum, as a theologian, and that of a great light of his Church, whom he himself declares to be "widely venerated as an authority, and whose orthodoxy has never been questioned." But Mr. Mivart does not hesitate to push his attempt to harmonise science with Catholic orthodoxy to its utmost limit; and, while assuming that the soul of man "arises from immediate and direct creation," he supposes that his body was "formed at first (as now in each separate individual) by derivative, or secondary creation, through natural laws" (p. 331). This means, I presume, that an animal, having the corporeal form and bodily powers of man, may have been developed out of some lower form of life by a process of evolution; and that, after this anthropoid animal had existed for a longer or shorter time, God made a soul by direct creation, and put it into the manlike body, which, heretofore, had been devoid of that _anima rationalis_, which is supposed to be man's distinctive character. This hypothesis is incapable of either proof or disproof, and therefore may be true; but if Suarez is any authority, it is not Catholic doctrine. "Nulla est in homine forma educta de potentia materiæ," [Footnote: Disput. xv. § x. No. 27.] is a dictum which is absolutely inconsistent with the doctrine of the natural evolution of any vital manifestation of the human body. Moreover, if man existed as an animal before he was provided with a rational soul, he must, in accordance with the elementary requirements of the philosophy in which Mr. Mivart delights, have possessed a distinct sensitive and vegetative soul, or souls. Hence, when the "breath of life" was breathed into the manlike animal's nostrils, he must have already been a living and feeling creature. But Suarez particularly discusses this point, and not only rejects Mr. Mivart's view, but adopts language of very theological strength regarding it. "Possent præterea his adjungi argumenta theologica, ut est illud quod sumitur ex illis verbis Genes. 2. _Formavit Deus hominem ex limo terræ et inspiravit in faciem ejus spiraculum vitæ et factus est homo in animam viventem_: ille enim spiritus, quam Deus spiravit, anima rationalis fuit, et PER EADEM FACTUS EST HOMO VIVENS, ET CONSQUENTER, ETIAM SENTIENS. "Aliud est ex VIII. Synodo Generali quæ est Constantinopolitana IV. can. 11, qui sic habet. _Apparet quosdam in tantum impietatis venisse ut homines duas animas habere dogmatizent: talis igitur impietatis inventores et similes sapientes, cum Vetus et Novum Testamentum omnesque Ecclesiæ patres unam animam rationalem hominem habere asseverent, Sancta et universalis Synodus anathematizat_." [FOOTNOTE: Disput. xv. "De causa formali substantiali," § x. No. 24.] Moreover, if the animal nature of man was the result of evolution, so must that of woman have been. But the Catholic doctrine, according to Suarez, is that woman was, in the strictest and most literal sense of the words, made out of the rib of man. "Nihilominus sententia Catholica est, verba illa Scripturæ esse ad literam intelligenda. AC PROINDE VERE, AC REALITER, TULISSE DEUM COSTAM ADAMÆ, ET, EX ILLA, CORPUS EVÆ FORMASSE." [Footnote: _Tractatus de Opere_, Lib. III. "De hominis creatione," cap. ii. No. 3.] Nor is there any escape in the supposition that some woman existed before Eve, after the fashion of the Lilith of the rabbis; since Suarez qualifies that notion, along with some other Judaic imaginations, as simply "damnabilis." [Footnote: _Ibid_. Lib. III. cap. iv. Nos. 8 and 9] After the perusal of the "Tractatus de Opere" it is, in fact, impossible to admit that Suarez held any opinion respecting the origin of species, except such as is consistent with the strictest and most literal interpretation of the words of Genesis. For Suarez, it is Catholic doctrine, that the world was made in six natural days. On the first of these days the _materia prima_ was made out of nothing, to receive afterwards those "substantial forms" which moulded it into the universe of things; on the third day, the ancestors of all living plants suddenly came into being, full-grown, perfect, and possessed of all the properties which now distinguish them; while, on the fifth and sixth days, the ancestors of all existing animals were similarly caused to exist in their complete and perfect state, by the infusion of their appropriate material substantial forms into the matter which had already been created. Finally, on the sixth day, the _anima rationalis_--that rational and immortal substantial form which is peculiar to man--was created out of nothing, and "breathed into" a mass of matter which, till then, was mere dust of the earth, and so man arose. But the species man was represented by a solitary male individual, until the Creator took out one of his ribs and fashioned it into a female. This is the view of the "Genesis of Species" held by Suarez to be the only one consistent with Catholic faith: it is because he holds this view to be Catholic that he does not hesitate to declare St. Augustin unsound, and St. Thomas Aquinas guilty of weakness, when the one swerved from this view and the other tolerated the deviation. And, until responsible Catholic authority--say, for example, the Archbishop of Westminster--formally declares that Suarez was wrong, and that Catholic priests are free to teach their flocks that the world was _not_ made in six natural days, and that plants and animals were _not_ created in their perfect and complete state, but have been evolved by natural processes through long ages from certain germs in which they were potentially contained, I, for one, shall feel bound to believe that the doctrines of Suarez are the only ones which are sanctioned by Infallible Authority, as represented by the Holy Father and the Catholic Church. I need hardly add that they are as absolutely denied and repudiated by Scientific Authority, as represented by Reason and Fact. The question whether the earth and the immediate progenitors of its present living population were made in six natural days or not is no longer one upon which two opinions can be held. The fact that it did not so come into being stands upon as sound a basis as any fact of history whatever. It is not true that existing plants and animals came into being within three days of the creation of the earth out of nothing, for it is certain that innumerable generations of other plants and animals lived upon the earth before its present population. And when, Sunday after Sunday, men who profess to be our instructors in righteousness read out the statement, "In six days the Lord made heaven and earth, the sea, and all that in them is," in innumerable churches, they are either propagating what they may easily know, and, therefore, are bound to know, to be falsities; or, if they use the words in some non-natural sense, they fall below the moral standard of the much-abused Jesuit. Thus far the contradiction between Catholic verity and Scientific verity is complete and absolute, quite independently of the truth or falsehood of the doctrine of evolution. But, for those who hold the doctrine of evolution, all the Catholic verities about the creation of living beings must be no less false. For them, the assertion that the progenitors of all existing plants were made on the third day, of animals on the fifth and sixth days, in the forms they now present, is simply false. Nor can they admit that man was made suddenly out of the dust of the earth; while it would be an insult to ask an evolutionist whether he credits the preposterous fable respecting the fabrication of woman to which Suarez pins his faith. If Suarez has rightly stated Catholic doctrine, then is evolution utter heresy. And such I believe it to be. In addition to the truth of the doctrine of evolution, indeed, one of its greatest merits in my eyes, is the fact that it occupies a position of complete and irreconcilable antagonism to that vigorous and consistent enemy of the highest intellectual, moral, and social life of mankind--the Catholic Church. No doubt, Mr. Mivart, like other putters of new wine into old bottles, is actuated by motives which are worthy of respect, and even of sympathy; but his attempt has met with the fate which the Scripture prophesies for all such. Catholic theology, like all theologies which are based upon the assumption of the truth of the account of the origin of things given in the Book of Genesis, being utterly irreconcilable with the doctrine of evolution, the student of science, who is satisfied that the evidence upon which the doctrine of evolution rests, is incomparably stronger and better than that upon which the supposed authority of the Book of Genesis rests, will not trouble himself further with these theologies, but will confine his attention to such arguments against the view he holds as are based upon purely scientific data--and by scientific data I do not merely mean the truths of physical, mathematical, or logical science, but those of moral and metaphysical science. For by science I understand all knowledge which rests upon evidence and reasoning of a like character to that which claims our assent to ordinary scientific propositions. And if any one is able to make good the assertion that his theology rests upon valid evidence and sound reasoning, then it appears to me that such theology will take its place as a part of science. The present antagonism between theology and science does not arise from any assumption by the men of science that all theology must necessarily be excluded from science, but simply because they are unable to allow that reason and morality have two weights and two measures; and that the belief in a proposition, because authority tells you it is true, or because you wish to believe it, which is a high crime and misdemeanour when the subject matter of reasoning is of one kind, becomes under the _alias_ of "faith" the greatest of all virtues when the subject matter of reasoning is of another kind. The Bishop of Brechin said well the other day:--"Liberality in religion--I do not mean tender and generous allowances for the mistakes of others--is only unfaithfulness to truth." [Footnote: Charge at the Diocesan Synod of Brechin. _Scotsman_, Sept. 14, 1871.] And, with the same qualification, I venture to paraphrase the Bishop's dictum: "Ecclesiasticism in science is only unfaithfulness to truth." Elijah's great question, "Will you serve God or Baal? Choose ye," is uttered audibly enough in the ears of every one of us as we come to manhood. Let every man who tries to answer it seriously ask himself whether he can be satisfied with the Baal of authority, and with all the good things his worshippers are promised in this world and the next. If he can, let him, if he be so inclined, amuse himself with such scientific implements as authority tells him are safe and will not cut his fingers; but let him not imagine he is, or can be, both a true son of the Church and a loyal soldier of science. And, on the other hand, if the blind acceptance of authority appears to him in its true colours, as mere private judgment _in excelsis_, and if he have the courage to stand alone, face to face with the abyss of the eternal and unknowable, let him be content, once for all, not only to renounce the good things promised by "Infallibility," but even to bear the bad things which it prophesies; content to follow reason and fact in singleness and honesty of purpose, wherever they may lead, in the sure faith that a hell of honest men will, to him, be more endurable than a paradise full of angelic shams. Mr. Mivart asserts that "without a belief in a personal God there is no religion worthy of the name." This is a matter of opinion. But it may be asserted, with less reason to fear contradiction, that the worship of a personal God, who, on Mr. Mivart's hypothesis, must have used language studiously calculated to deceive His creatures and worshippers, is "no religion worthy of the name." "Incredible est, Deum illis verbis ad populum fuisse locutum quibus deciperetur," is a verdict in which, for once, Jesuit casuistry concurs with the healthy moral sense of all mankind. Having happily got quit of the theological aspect of evolution, the supporter of that great truth who turns to the scientific objections which are brought against it by recent criticism, finds, to his relief, that the work before him is greatly lightened by the spontaneous retreat of the enemy from nine-tenths of the territory which he occupied ten years ago. Even the Quarterly Reviewer not only abstains from venturing to deny that evolution has taken place, but he openly admits that Mr. Darwin has forced on men's minds "a recognition of the probability, if not more, of evolution, and of the certainty of the action of natural selection" (p. 49). I do not quite see, myself, how, if the action of natural selection is _certain_, the occurrence of evolution is only _probable_; inasmuch as the development of a new species by natural selection is, so far as it goes, evolution. However, it is not worth while to quarrel with the precise terms of a sentence which shows that the high water mark of intelligence among those most respectable of Britons, the readers of the _Quarterly Review_, has now reached such a level that the next tide may lift them easily and pleasantly on the once-dreaded shore of evolution. Nor, having got there, do they seem likely to stop, until they have reached the inmost heart of that great region, and accepted the ape ancestry of, at any rate, the body of man. For the Reviewer admits that Mr. Darwin can be said to have established: "That if the various kinds of lower animals have been evolved one from the other by a process of natural generation or evolution, then it becomes highly probable, _a priori_, that man's body has been similarly evolved; but this, in such a case, becomes equally probable from the admitted fact that he is an animal at all" (p. 65). From the principles laid down in the last sentence it would follow that if man were constructed upon a plan as different from that of any other animal as that of a sea-urchin is from that of a whale, it would be "equally probable" that he had been developed from some other animal as it is now, when we know that for every bone, muscle, tooth, and even pattern of tooth, in man, there is a corresponding bone, muscle, tooth, and pattern of tooth, in an ape. And this shows one of two things--either that the Quarterly Reviewer's notions of probability are peculiar to himself, or that he has such an overpowering faith in the truth of evolution that no extent of structural break between one animal and another is sufficient to destroy his conviction that evolution has taken place. But this by the way. The importance of the admission that there is nothing in man's physical structure to interfere with his having been evolved from an ape is not lessened because it is grudgingly made and inconsistently qualified. And instead of jubilating over the extent of the enemy's retreat, it will be more worth while to lay siege to his last stronghold--the position that there is a distinction in kind between the mental faculties of man and those of brutes, and that in consequence of this distinction in kind no gradual progress from the mental faculties of the one to those of the other can have taken place. The Quarterly Reviewer entrenches himself within formidable-looking psychological outworks, and there is no getting at him without attacking them one by one. He begins by laying down the following proposition. "'Sensation' is not 'thought,' and no amount of the former would constitute the most rudimentary condition of the latter, though sensations supply the conditions for the existence of 'thought' or 'knowledge'" (p. 67). This proposition is true, or not, according to the sense in which the word "thought" is employed. Thought is not uncommonly used in a sense co-extensive with consciousness, and, especially, with those states of consciousness we call memory. If I recall the impression made by a colour or an odour, and distinctly remember blueness or muskiness, I may say with perfect propriety that I "think of" blue or musk; and, so long as the thought lasts, it is simply a faint reproduction of the state of consciousness to which I gave the name in question, when it first became known to me as a sensation. Now, if that faint reproduction of a sensation, which we call the memory of it, is properly termed a thought, it seems to me to be a somewhat forced proceeding to draw a hard and fast line of demarcation between thoughts and sensations. If sensations are not rudimentary thoughts, it may be said that some thoughts are rudimentary sensations. No amount of sound constitutes an echo, but for all that no one would pretend that an echo is something of totally different nature from a sound. Again, nothing can be looser, or more inaccurate, than the assertion that "sensations supply the conditions for the existence of thought or knowledge." If this implies that sensations supply the conditions for the existence of our memory of sensations or of our thoughts about sensations, it is a truism which it is hardly worth while to state so solemnly. If it implies that sensations supply anything else, it is obviously erroneous. And if it means, as the context would seem to show it does, that sensations are the subject-matter of all thought or knowledge, then it is no less contrary to fact, inasmuch as our emotions, which constitute a large part of the subject-matter of thought or of knowledge, are not sensations. More eccentric still is the Quarterly Reviewer's next piece of psychology. "Altogether, we may clearly distinguish at least six kinds of action to which the nervous system ministers:-- "I. That in which impressions received result in appropriate movements without the intervention of sensation or thought, as in the cases of injury above given.--This is the reflex action of the nervous system. "II. That in which stimuli from without result in sensations through the agency of which their due effects are wrought out.--Sensation. "III. That in which impressions received result in sensations which give rise to the observation of sensible objects.--Sensible perception. "IV. That in which sensations and perceptions continue to coalesce, agglutinate, and combine in more or less complex aggregations, according to the laws of the association of sensible perceptions.--Association. "The above four groups contain only indeliberate operations, consisting, as they do at the best, but of mere _presentative_ sensible ideas in no way implying any reflective or _representative_ faculty. Such actions minister to and form _Instinct_. Besides these, we may distinguish two other kinds of mental action, namely:-- "V. That in which sensations and sensible perceptions are reflected on by thought, and recognised as our own, and we ourselves recognised by ourselves as affected and perceiving.--Self-consciousness. "VI. That in which we reflect upon our sensations or perceptions, and ask what they are, and why they are.--Reason. "These two latter kinds of action are deliberate operations, performed, as they are, by means of representative ideas implying the use of a _reflective representative_ faculty. Such actions distinguish the _intellect_ or rational faculty. Now, we assert that possession in perfection of all the first four (_presentative_) kinds of action by no means implies the possession of the last two (_representative_) kinds. All persons, we think, must admit the truth of the following proposition:-- "Two faculties are distinct, not in degree but _in kind_, if we may possess the one in perfection without that fact implying that we possess the other also. Still more will this be the case if the two faculties tend to increase in an inverse ratio. Yet this is the distinction between the _instinctive_ and the _intellectual_ parts of man's nature. "As to animals, we fully admit that they may possess all the first four groups of actions--that they may have, so to speak, mental images of sensible objects combined in all degrees of complexity, as governed by the laws of association. We deny to them, on the other hand, the possession of the last two kinds of mental action. We deny them, that is, the power of reflecting on their own existences, or of inquiring into the nature of objects and their causes. We deny that they know that they know or know themselves in knowing. In other words, we deny them _reason_. The possession of the presentative faculty, as above explained, in no way implies that of the reflective faculty; nor does any amount of direct operation imply the power of asking the reflective question before mentioned, as to 'what' and 'why.'" (_Loc. cit_. pp. 67, 68.) Sundry points are worthy of notice in this remarkable account of the intellectual powers. In the first place the Reviewer ignores emotion and volition, though they are no inconsiderable "kinds of action to which the nervous system ministers," and memory has a place in his classification only by implication. Secondly, we are told that the second "kind of action to which the nervous system ministers" is "that in which stimuli from without result in sensations through the agency of which their due effects are wrought out.--Sensation." Does this really mean that, in the writer's opinion, "sensation" is the "agent" by which the "due effect" of the stimulus, which gives rise to sensation, is "wrought out"? Suppose somebody runs a pin into me. The "due effect" of that particular stimulus will probably be threefold; namely, a sensation of pain, a start, and an interjectional expletive. Does the Quarterly Reviewer really think that the "sensation" is the "agent" by which the other two phenomena are wrought out? But these matters are of little moment to anyone but the Reviewer and those persons who may incautiously take their physiology, or psychology, from him. The really interesting point is this, that when he fully admits that animals "may possess all the first four groups of actions," he grants all that is necessary for the purposes of the evolutionist. For he hereby admits that in animals "impressions received result in sensations which give rise to the observation of sensible objects," and that they have what he calls "sensible perception." Nor was it possible to help the admission; for we have as much reason to ascribe to animals, as we have to attribute to our fellow-men, the power, not only of perceiving external objects as external, and thus practically recognizing the difference between the self and the not-self; but that of distinguishing between like and unlike, and between simultaneous and successive things. When a gamekeeper goes out coursing with a greyhound in leash, and a hare crosses the field of vision, he becomes the subject of those states of consciousness we call visual sensation, and that is all he receives from without. Sensation, as such, tells him nothing whatever about the cause of these states of consciousness; but the thinking faculty instantly goes to work upon the raw material of sensation furnished to it through the eye, and gives rise to a train of thoughts. First comes the thought that there is an object at a certain distance; then arises another thought--the perception of the likeness between the states of consciousness awakened by this object to those presented by memory, as, on some former occasion, called up by a hare; this is succeeded by another thought of the nature of an emotion--namely, the desire to possess the hare; then follows a longer or shorter train of other thoughts, which end in a volition and an act--the loosing of the greyhound from the leash. These several thoughts are the concomitants of a process which goes on in the nervous system of the man. Unless the nerve-elements of the retina, of the optic nerve, of the brain, of the spinal cord, and of the nerves of the arms, went through certain physical changes in due order and correlation, the various states of consciousness which have been enumerated would not make their appearance. So that in this, as in all other intellectual operations, we have to distinguish two sets of successive changes--one in the physical basis of consciousness, and the other in consciousness itself; one set which may, and doubtless will, in course of time, be followed through all their complexities by the anatomist and the physicist, and one of which only the man himself can have immediate knowledge. As it is very necessary to keep up a clear distinction between these two processes, let the one be called _neurosis_, and the other _psychosis_. When the gamekeeper was first trained to his work every step in the process of neurosis was accompanied by a corresponding step in that of psychosis, or nearly so. He was conscious of seeing something, conscious of making sure it was a hare, conscious of desiring to catch it, and therefore to loose the greyhound at the right time, conscious of the acts by which he let the dog out of the leash. But with practice, though the various steps of the neurosis remain--for otherwise the impression on the retina would not result in the loosing of the dog--the great majority of the steps of the psychosis vanish, and the loosing of the dog follows unconsciously, or as we say, without thinking about it, upon the sight of the hare. No one will deny that the series of acts which originally intervened between the sensation and the letting go of the dog were, in the strictest sense, intellectual and rational operations. Do they cease to be so when the man ceases to be conscious of them? That depends upon what is the essence and what the accident of those operations, which, taken together, constitute ratiocination. Now ratiocination is resolvable into predication, and predication consists in marking, in some way, the existence, the co-existence, the succession, the likeness and unlikeness, of things or their ideas. Whatever does this, reasons; and if a machine produces the effects of reason, I see no more ground for denying to it the reasoning power, because it is unconscious, than I see for refusing to Mr. Babbage's engine the title of a calculating machine on the same grounds. Thus it seems to me that a gamekeeper reasons, whether he is conscious or unconscious, whether his reasoning is carried on by neurosis alone, or whether it involves more or less psychosis. And if this is true of the gamekeeper, it is also true of the greyhound. The essential resemblances in all points of structure and function, so far as they can be studied, between the nervous system of the man and that of the dog, leave no reasonable doubt that the processes which go on in the one are just like those which take place in the other. In the dog, there can be no doubt that the nervous matter which lies between the retina and the muscles undergoes a series of changes, precisely analogous to those which, in the man, give rise to sensation, a train of thought, and volition. Whether this neurosis is accompanied by such psychosis as ours it is impossible to say; but those who deny that the nervous changes, which, in the dog, correspond with those which underlie thought in a man, are accompanied by consciousness, are equally bound to maintain that those nervous changes in the dog, which correspond with those which underlie sensation in a man, are also unaccompanied by consciousness. In other words, if there is no ground for believing that a dog thinks, neither is there any for believing that he feels. As is well known, Descartes boldly faced this dilemma, and maintained that all animals were mere machines and entirely devoid of consciousness. But he did not deny, nor can anyone deny, that in this case they are reasoning machines, capable of performing all those operations which are performed by the nervous system of man when he reasons. For even supposing that in man, and in man only, psychosis is superadded to neurosis--the neurosis which is common to both man and animal gives their reasoning processes a fundamental unity. But Descartes' position is open to very serious objections if the evidence that animals feel is insufficient to prove that they really do so. What is the value of the evidence which leads one to believe that one's fellow-man feels? The only evidence in this argument of analogy is the similarity of his structure and of his actions to one's own. And if that is good enough to prove that one's fellow-man feels, surely it is good enough to prove that an ape feels. For the differences of structure and function between men and apes are utterly insufficient to warrant the assumption that while men have those states of consciousness we call sensations apes have nothing of the kind. Moreover, we have as good evidence that apes are capable of emotion and volition as we have that men other than ourselves are. But if apes possess three out of the four kinds of states of consciousness which we discover in ourselves, what possible reason is there for denying them the fourth? If they are capable of sensation, emotion, and volition, why are they to be denied thought (in the sense of predication)? No answer has ever been given to these questions. And as the law of continuity is as much opposed, as is the common sense of mankind, to the notion that all animals are unconscious machines, it may safely be assumed that no sufficient answer ever will be given to them. There is every reason to believe that consciousness is a function of nervous matter, when that nervous matter has attained a certain degree of organisation, just as we know the other "actions to which the nervous system ministers," such as reflex action and the like, to be. As I have ventured to state my view of the matter elsewhere, "our thoughts are the expression of molecular changes in that matter of life which is the source of our other vital phenomena." Mr. Wallace objects to this statement in the following terms:-- "Not having been able to find any clue in Professor Huxley's writings to the steps by which he passes from those vital phenomena, which consist only, in their last analysis, of movements by particles of matter, to those other phenomena which we term thought, sensation, or consciousness; but, knowing that so positive an expression of opinion from him will have great weight with many persons, I shall endeavour to show, with as much brevity as is compatible with clearness, that this theory is not only incapable of proof, but is also, as it appears to me, inconsistent with accurate conceptions of molecular physics." With all respect for Mr. Wallace, it appears to me that his remarks are entirely beside the question. I really know nothing whatever, and never hope to know anything, of the steps by which the passage from molecular movement to states of consciousness is effected; and I entirely agree with the sense of the passage which he quotes from Professor Tyndall, apparently imagining that it is in opposition to the view I hold. All that I have to say is, that, in my belief, consciousness and molecular action are capable of being expressed by one another, just as heat and mechanical action are capable of being expressed in terms of one another. Whether we shall ever be able to express consciousness in foot-pounds, or not, is more than I will venture to say; but that there is evidence of the existence of some correlation between mechanical motion and consciousness, is as plain as anything can be. Suppose the poles of an electric battery to be connected by a platinum wire. A certain intensity of the current gives rise in the mind of a bystander to that state of consciousness we call a "dull red light"--a little greater intensity to another which we call a "bright red light;" increase the intensity, and the light becomes white; and, finally, it dazzles, and a new state of consciousness arises, which we term pain. Given the same wire and the same nervous apparatus, and the amount of electric force required to give rise to these several states of consciousness will be the same, however often the experiment is repeated. And as the electric force, the light waves, and the nerve-vibrations caused by the impact of the light-waves on the retina, are all expressions of the molecular changes which are taking place in the elements of the battery; so consciousness is, in the same sense, an expression of the molecular changes which take place in that nervous matter, which is the organ of consciousness. And, since this, and any number of similar examples that may be required, prove that one form of consciousness, at any rate, is, in the strictest sense, the expression of molecular change, it really is not worth while to pursue the inquiry, whether a fact so easily established is consistent with any particular system of molecular physics or not. Mr. Wallace, in fact, appears to me to have mixed up two very distinct propositions: the one, the indisputable truth that consciousness is correlated with molecular changes in the organ of consciousness; the other, that the nature of that correlation is known, or can be conceived, which is quite another matter. Mr. Wallace, presumably, believes in that correlation of phenomena which we call cause and effect as firmly as I do. But if he has ever been able to form the faintest notion how a cause gives rise to its effect, all I can say is that I envy him. Take the simplest case imaginable--suppose a ball in motion to impinge upon another ball at rest. I know very well, as a matter of fact, that the ball in motion will communicate some of its motion to the ball at rest, and that the motion of the two balls, after collision, is precisely correlated with the masses of both balls and the amount of motion of the first. But how does this come about? In what manner can we conceive that the _vis viva_ of the first ball passes into the second? I confess I can no more form any conception of what happens in this case, than I can of what takes place when the motion of particles of my nervous matter, caused by the impact of a similar ball gives rise to the state of consciousness I call pain. In ultimate analysis everything is incomprehensible, and the whole object of science is simply to reduce the fundamental incomprehensibilities to the smallest possible number. But to return to the Quarterly Reviewer. He admits that animals have "mental images of sensible objects, combined in all degrees of complexity, as governed by the laws of association." Presumably, by this confused and imperfect statement the Reviewer means to admit more than the words imply. For mental images of sensible objects, even though "combined in all degrees of complexity," are, and can be, nothing more than mental images of sensible objects. But judgments, emotions, and volitions cannot by any possibility be included under the head of "mental images of sensible objects." If the greyhound had no better mental endowment than the Reviewer allows him, he might have the "mental image" of the "sensible object"--the hare--and that might be combined with the mental images of other sensible objects, to any degree of complexity, but he would have no power of judging it to be at a certain distance from him; no power of perceiving its similarity to his memory of a hare; and no desire to get at it. Consequently he would stand stock still, and the noble art of coursing would have no existence. On the other hand, as that art is largely practised, it follows that greyhounds alone possess a number of mental powers, the existence of which, in any animal, is absolutely denied by the Quarterly Reviewer. Finally, what are the mental powers which he reserves as the especial prerogative of man? They are two. First, the recognition of "ourselves by ourselves as affected and perceiving.--Self-consciousness." Secondly. "The reflection upon our sensations and perceptions, and asking what they are and why they are.--Reason." To the faculty defined in the last sentence, the Reviewer, without assigning the least ground for thus departing from both common usage and technical propriety, applies the name of reason. But if man is not to be considered a reasoning being, unless he asks what his sensations and perceptions are, and why they are, what is a Hottentot, or an Australian "black-fellow"; or what the "swinked hedger" of an ordinary agricultural district? Nay, what becomes of an average country squire or parson? How many of these worthy persons who, as their wont is, read the _Quarterly Review_, would do other than stand agape, if you asked them whether they had ever reflected what their sensations and perceptions are and why they are? So that if the Reviewer's new definition of reason be correct, the majority of men, even among the most civilised nations, are devoid of that supreme characteristic of manhood. And if it be as absurd as I believe it to be, then, as reason is certainly not self-consciousness, and since it, as certainly, is one of the "actions to which the nervous system ministers," we must, if the Reviewer's classification is to be adopted, seek it among those four faculties which he allows animals to possess. And thus, for the second time, he really surrenders, while seeming to defend, his position. The Quarterly Reviewer, as we have seen, lectures the evolutionists upon their want of knowledge of philosophy altogether. Mr. Mivart is not less pained at Mr. Darwin's ignorance of moral science. It is grievous to him that Mr. Darwin (and _nous autres_) should not have grasped the elementary distinction between material and formal morality; and he lays down as an axiom, of which no tyro ought to be ignorant, the position that "acts, unaccompanied by mental acts of conscious will directed towards the fulfilment of duty," are "absolutely destitute of the most incipient degree of real or formal goodness." Now this may be Mr. Mivart's opinion, but it is a proposition which really does not stand on the footing of an undisputed axiom. Mr. Mill denies it in his work on Utilitarianism. The most influential writer of a totally opposed school, Mr. Carlyle, is never weary of denying it, and upholding the merit of that virtue which is unconscious; nay, it is, to my understanding, extremely hard to reconcile Mr. Mivart's dictum with that noble summary of the whole duty of man--"Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength; and thou shalt love thy neighbour as thyself." According to Mr. Mivart's definition, the man who loves God and his neighbour, and, out of sheer love and affection for both, does all he can to please them, is, nevertheless, destitute of a particle of real goodness. And it further happens that Mr. Darwin, who is charged by Mr. Mivart with being ignorant of the distinction between material and formal goodness, discusses the very question at issue in a passage which is well worth reading (vol. i. p. 87), and also comes to a conclusion opposed to Mr. Mivart's axiom. A proposition which has been so much disputed and repudiated, should, under no circumstances, have been thus confidently assumed to be true. For myself, I utterly reject it, inasmuch as the logical consequence of the adoption of any such principle is the denial of all moral value to sympathy and affection. According to Mr. Mivart's axiom, the man who, seeing another struggling in the water, leaps in at the risk of his own life to save him, does that which is "destitute of the most incipient degree of real goodness," unless, as he strips off his coat, he says to himself, "Now, mind, I am going to do this because it is my duty and for no other reason;" and the most beautiful character to which humanity can attain, that of the man who does good without thinking about it, because he loves justice and mercy and is repelled by evil, has no claim on our moral approbation. The denial that a man acts morally because he does not think whether he does so or not, may be put upon the same footing as the denial of the title of an arithmetician to the calculating boy, because he did not know how he worked his sums. If mankind ever generally accept and act upon Mr. Mivart's axiom, they will simply become a set of most unendurable prigs; but they never have accepted it, and I venture to hope that evolution has nothing so terrible in store for the human race. But if an action, the motive of which is nothing but affection or sympathy, may be deserving of moral approbation and really good, who that has ever had a dog of his own will deny that animals are capable of such actions? Mr. Mivart indeed says:--"It may be safely affirmed, however, that there is no trace in brutes of any actions simulating morality which are not explicable by the fear of punishment, by the hope of pleasure, or by personal affection" (p. 221). But it may be affirmed, with equal truth, that there is no trace in men of any actions which are not traceable to the same motives. If a man does anything, he does it either because he fears to be punished if he does not do it, or because he hopes to obtain pleasure by doing it, or because he gratifies his affections [Footnote: In separating pleasure and the gratification of affection, I simply follow Mr. Mivart without admitting the justice of the separation.] by doing it. Assuming the position of the absolute moralists, let it be granted that there is a perception of right and wrong innate in every man. This means, simply, that when certain ideas are presented to his mind, the feeling of approbation arises; and when certain others, the feeling of disapprobation. To do your duty is to earn the approbation of your conscience, or moral sense; to fail in your duty is to feel its disapprobation, as we all say. Now, is approbation a pleasure or a pain? Surely a pleasure. And is disapprobation a pleasure or a pain? Surely a pain. Consequently, all that is really meant by the absolute moralists is that there is, in the very nature of man, something which enables him to be conscious of these particular pleasures and pains. And when they talk of immutable and eternal principles of morality, the only intelligible sense which I can put upon the words, is that the nature of man being what it is, he always has been, and always will be, capable of feeling these particular pleasures and pains. _À priori,_ I have nothing to say against this proposition. Admitting its truth, I do not see how the moral faculty is on a different footing from any of the other faculties of man. If I choose to say that it is an immutable and eternal law of human nature that "ginger is hot in the mouth," the assertion has as much foundation of truth as the other, though I think it would be expressed in needlessly pompous language. I must confess that I have never been able to understand why there should be such a bitter quarrel between the intuitionists and the utilitarians. The intuitionist is, after all, only a utilitarian who believes that a particular class of pleasures and pains has an especial importance, by reason of its foundation in the nature of man, and its inseparable connection with his very existence as a thinking being. And as regards the motive of personal affection: Love, as Spinoza profoundly says, is the association of pleasure with that which is loved. [Footnote: "Nempe, Amor nihil aliud est, quam Lætitia, concomitante idea causæ externæ."--_Ethices_, III. xiii.] Or, to put it to the common sense of mankind, is the gratification of affection a pleasure or a pain? Surely a pleasure. So that whether the motive which leads us to perform an action is the love of our neighbour, or the love of God, it is undeniable that pleasure enters into that motive. Thus much in reply to Mr. Mivart's arguments. I cannot but think that it is to be regretted that he ekes them out by ascribing to the doctrines of the philosophers with whom he does not agree, logical consequences which have been over and over again proved not to flow from them: and when reason fails him, tries the effect of an injurious nickname. According to the views of Mr. Spencer, Mr. Mill, and Mr. Darwin, Mr. Mivart tells us, "_virtue is a mere kind of retrieving:_" and, that we may not miss the point of the joke, he puts it in italics. But what if it is? Does that make it less virtue? Suppose I say that sculpture is a "mere way" of stone-cutting, and painting a "mere way" of daubing canvas, and music a "mere way" of making a noise, the statements are quite true; but they only show that I see no other method of depreciating some of the noblest aspects of humanity than that of using language in an inadequate and misleading sense about them. And the peculiar inappropriateness of this particular nickname to the views in question, arises from the circumstance which Mr. Mivart would doubtless have recollected, if his wish to ridicule had not for the moment obscured his judgment--that whether the law of evolution applies to man or not, that of hereditary transmission certainly does. Mr. Mivart will hardly deny that a man owes a large share of the moral tendencies which he exhibits to his ancestors; and the man who inherits a desire to steal from a kleptomaniac, or a tendency to benevolence from a Howard, is, so far as he illustrates hereditary transmission, comparable to the dog who inherits the desire to fetch a duck out of the water from his retrieving sire. So that, evolution, or no evolution, moral qualities are comparable to a "kind of retrieving;" though the comparison, if meant for the purposes of casting obloquy on evolution, does not say much for the fairness of those who make it. The Quarterly Reviewer and Mr. Mivart base their objections to the evolution of the mental faculties of man from those of some lower animal form upon what they maintain to be a difference in kind between the mental and moral faculties of men and brutes; and I have endeavoured to show, by exposing the utter unsoundness of their philosophical basis, that these objections are devoid of importance. The objections which Mr. Wallace brings forward to the doctrine of the evolution of the mental faculties of man from those of brutes by natural causes, are of a different order, and require separate consideration. If I understand him rightly, he by no means doubts that both the bodily and the mental faculties of man have been evolved from those of some lower animal; but he is of opinion that some agency beyond that which has been concerned in the evolution of ordinary animals has been operative in the case of man. "A superior intelligence has guided the development of man in a definite direction and for a special purpose, just as man guides the development of many animal and vegetable forms." [Footnote: "The Limits of Natural Selection as applied to Man" (_loc. cit._ p. 359).] I understand this to mean that, just as the rock-pigeon has been produced by natural causes, while the evolution of the tumbler from the blue rock has required the special intervention of the intelligence of man, so some anthropoid form may have been evolved by variation and natural selection; but it could never have given rise to man, unless some superior intelligence had played the part of the pigeon-fancier. According to Mr. Wallace, "whether we compare the savage with the higher developments of man, or with the brutes around him, we are alike driven to the conclusion, that, in his large and well-developed brain, he possesses an organ quite disproportioned to his requirements" (p. 343); and he asks, "What is there in the life of the savage but the satisfying of the cravings of appetite in the simplest and easiest way? What thoughts, idea, or actions are there that raise him many grades above the elephant or the ape?" (p. 342.) I answer Mr. Wallace by citing a remarkable passage which occurs in his instructive paper on "Instinct in Man and Animals." "Savages make long journeys in many directions, and, their whole faculties being directed to the subject, they gain a wide and accurate knowledge of the topography, not only of their own district, but of all the regions round about. Every one who has travelled in a new direction communicates his knowledge to those who have travelled less, and descriptions of routes and localities, and minute incidents of travel, form one of the main staples of conversation around the evening fire. Every wanderer or captive from another tribe adds to the store of information, and, as the very existence of individuals and of whole families and tribes depends upon the completeness of this knowledge, all the acute perceptive faculties of the adult savage are directed to acquiring and perfecting it. The good hunter or warrior thus comes to know the bearing of every hill and mountain range, the directions and junctions of all the streams, the situation of each tract characterised by peculiar vegetation, not only within the area he has himself traversed, but perhaps for a hundred miles around it. His acute observation enables him to detect the slightest undulations of the surface, the various changes of subsoil and alterations in the character of the vegetation that would be quite imperceptible to a stranger. His eye is always open to the direction in which he is going; the mossy side of trees, the presence of certain plants under the shade of rocks, the morning and evening flight of birds, are to him indications of direction almost as sure as the sun in the heavens" (pp. 207, 208). I have seen enough of savages to be able to declare that nothing can be more admirable than this description of what a savage has to learn. But it is incomplete. Add to all this the knowledge which a savage is obliged to gain of the properties of plants, of the characters and habits of animals, and of the minute indications by which their course is discoverable: consider that even an Australian can make excellent baskets and nets, and neatly fitted and beautifully balanced spears; that he learns to use these so as to be able to transfix a quartern loaf at sixty yards; and that very often, as in the case of the American Indians, the language of a savage exhibits complexities which a well-trained European finds it difficult to master: consider that every time a savage tracks his game he employs a minuteness of observation, and an accuracy of inductive and deductive reasoning which, applied to other matters, would assure some reputation to a man of science, and I think we need ask no further why he possesses such a fair supply of brains. In complexity and difficulty, I should say that the intellectual labour of a "good hunter or warrior" considerably exceeds that of an ordinary Englishman. The Civil Service Examiners are held in great terror by young Englishmen; but even their ferocity never tempted them to require a candidate to possess such a knowledge of a parish as Mr. Wallace justly points out savages may possess of an area a hundred miles or more in diameter. But suppose, for the sake of argument, that a savage has more brains than seems proportioned to his wants, all that can be said is that the objection to natural selection, if it be one, applies quite as strongly to the lower animals. The brain of a porpoise is quite wonderful for its mass, and for the development of the cerebral convolutions. And yet since we have ceased to credit the story of Arion, it is hard to believe that porpoises are much troubled with intellect: and still more difficult is it to imagine that their big brains are only a preparation for the advent of some accomplished cetacean of the future. Surely, again, a wolf must have too much brains, or else how is it that a dog with only the same quantity and form of brain is able to develop such singular intelligence? The wolf stands to the dog in the same relation as the savage to the man; and, therefore, if Mr. Wallace's doctrine holds good, a higher power must have superintended the breeding up of wolves from some inferior stock, in order to prepare them to become dogs. Mr. Wallace further maintains that the origin of some of man's mental faculties by the preservation of useful variations is not possible. Such, for example, are "the capacity to form ideal conceptions of space and time, of eternity and infinity; the capacity for intense artistic feelings of pleasure in form, colour, and composition; and for those abstract notions of form and number which render geometry and arithmetic possible." "How," he asks, "were all or any of these faculties first developed, when they could have been of no possible use to man in his early stages of barbarism?" Surely the answer is not far to seek. The lowest savages are as devoid of any such conceptions as the brutes themselves. What sort of conceptions of space and time, of form and number, can be possessed by a savage who has not got so far as to be able to count beyond five or six, who does not know how to draw a triangle or a circle, and has not the remotest notion of separating the particular quality we call form, from the other qualities of bodies? None of these capacities are exhibited by men, unless they form part of a tolerably advanced society. And, in such a society, there are abundant conditions by which a selective influence is exerted in favour of those persons who exhibit an approximation towards the possession of these capacities. The savage who can amuse his fellows by telling a good story over the nightly fire, is held by them in esteem and rewarded, in one way or another, for so doing--in other words, it is an advantage to him to possess this power. He who can carve a paddle, or the figure-head of a canoe better, similarly profits beyond his duller neighbour. He who counts a little better than others, gets most yams when barter is going on, and forms the shrewdest estimate of the numbers of an opposing tribe. The experience of daily life shows that the conditions of our present social existence exercise the most extraordinarily powerful selective influence in favour of novelists, artists, and strong intellects of all kinds; and it seems unquestionable that all forms of social existence must have had the same tendency, if we consider the indisputable facts that even animals possess the power of distinguishing form and number, and that they are capable of deriving pleasure from particular forms and sounds. If we admit, as Mr. Wallace does, that the lowest savages are not raised "many grades above the elephant and the ape;" and if we further admit, as I contend must be admitted, that the conditions of social life tend, powerfully, to give an advantage to those individuals who vary in the direction of intellectual or æsthetic excellence, what is there to interfere with the belief that these higher faculties, like the rest, owe their development to natural selection? Finally, with respect to the development of the moral sense out of the simple feelings of pleasure and pain, liking and disliking, with which the lower animals are provided, I can find nothing in Mr. Wallace's reasonings which has not already been met by Mr. Mill, Mr. Spencer, or Mr. Darwin. I do not propose to follow the Quarterly Reviewer and Mr. Mivart through the long string of objections in matters of detail which they bring against Mr. Darwin's views. Every one who has considered the matter carefully will be able to ferret out as many more "difficulties"; but he will also, I believe, fail as completely as they appear to me to have done, in bringing forward any fact which is really contradictory of Mr. Darwin's views. Occasionally, too, their objections and criticisms are based upon errors of their own. As, for example, when Mr. Mivart and the Quarterly Reviewer insist upon the resemblances between the eyes of _Cephalopoda_ and _Vertebrata_, quite forgetting that there are striking and altogether fundamental differences between them; or when the Quarterly Reviewer corrects Mr. Darwin for saying that the gibbons, "without having been taught, can walk or run upright with tolerable quickness, though they move awkwardly, and much less securely than man." The Quarterly Reviewer says, "This is a little misleading, inasmuch as it is not stated that this upright progression is effected by placing the enormously long arms behind the head, or holding them out backwards as a balance in progression." Now, before carping at a small statement like this, the Quarterly Reviewer should have made sure that he was quite right. But he happens to be quite wrong. I suspect he got his notion of the manner in which a gibbon walks from a citation in "Man's Place in Nature." But at that time I had not seen a gibbon walk. Since then I have, and I can testify that nothing can be more precise than Mr. Darwin's statement. The gibbon I saw walked without either putting his arms behind his head or holding them out backwards. All he did was to touch the ground with the outstretched fingers of his long arms now and then, just as one sees a man who carries a stick, but does not need one, touch the ground with it as he walks along. Again, a large number of the objections brought forward by Mr. Mivart and the Quarterly Reviewer apply to evolution in general, quite as much as to the particular form of that doctrine advocated by Mr. Darwin; or, to their notions of Mr. Darwin's views and not to what they really are. An excellent example of this class of difficulties is to be found in Mr. Mivart's chapter on "Independent Similarities of Structure." Mr. Mivart says that these cannot be explained by an "absolute and pure Darwinian," but "that an innate power and evolutionary law, aided by the corrective action of natural selection, should have furnished like needs with like aids, is not at all improbable" (p. 82). I do not exactly know what Mr. Mivart means by an "absolute and pure Darwinian;" indeed Mr. Mivart makes that creature hold so many singular opinions that I doubt if I can ever have seen one alive. But I find nothing in his statement of the view which he imagines to be originated by himself, which is really inconsistent with what I understand to be Mr. Darwin's views. I apprehend that the foundation of the theory of natural selection is the fact that living bodies tend incessantly to vary. This variation is neither indefinite, nor fortuitous, nor does it take place in all directions, in the strict sense of these words. Accurately speaking, it is not indefinite, nor does it take place in all directions, because it is limited by the general characters of the type to which the organism exhibiting the variation belongs. A whale does not tend to vary in the direction of producing feathers, nor a bird in the direction of developing whalebone. In popular language there is no harm in saying that the waves which break upon the sea-shore are indefinite, fortuitous, and break in all directions. In scientific language, on the contrary, such a statement would be a gross error, inasmuch as every particle of foam is the result of perfectly definite forces, operating according to no less definite laws. In like manner, every variation of a living form, however minute, however apparently accidental, is inconceivable except as the expression of the operation of molecular forces or "powers" resident within the organism. And, as these forces certainly operate according to definite laws, their general result is, doubtless, in accordance with some general law which subsumes them all. And there appears to be no objection to call this an "evolutionary law." But nobody is the wiser for doing so, or has thereby contributed, in the least degree, to the advance of the doctrine of evolution, the great need of which is a theory of variation. When Mr. Mivart tells us that his "aim has been to support the doctrine that these species have been evolved by ordinary _natural laws_ (for the most part unknown), aided by the _subordinate_ action of 'natural selection'" (pp. 332-3), he seems to be of opinion that his enterprise has the merit of novelty. All I can say is that I have never had the slightest notion that Mr. Darwin's aim is in any way different from this. If I affirm that "species have been evolved by variation [Footnote: Including under this head hereditary transmission.] (a natural process, the laws of which are for the most part unknown), aided by the subordinate action of natural selection," it seems to me that I enunciate a proposition which constitutes the very pith and marrow of the first edition of the "Origin of Species." And what the evolutionist stands in need of just now, is not an iteration of the fundamental principle of Darwinism, but some light upon the questions, What are the limits of variation? and, If a variety has arisen, can that variety be perpetuated, or even intensified, when selective conditions are indifferent, or perhaps unfavourable to its existence? I cannot find that Mr. Darwin has ever been very dogmatic in answering these questions. Formerly, he seems to have inclined to reply to them in the negative, while now his inclination is the other way. Leaving aside those broad questions of theology, philosophy, and ethics, by the discussion of which neither the Quarterly Reviewer nor Mr. Mivart can be said to have damaged Darwinism--whatever else they have injured--this is what their criticisms come to. They confound a struggle for some rifle-pits with an assault on the fortress. In some respects, finally, I can only characterise the Quarterly Reviewer's treatment of Mr. Darwin as alike unjust and unbecoming. Language of this strength requires justification, and on that ground I add the remarks which follow. The Quarterly Reviewer opens his essay by a careful enumeration of all those points upon which, during the course of thirteen years of incessant labour, Mr. Darwin has modified his opinions. It has often and justly been remarked, that what strikes a candid student of Mr. Darwin's works is not so much his industry, his knowledge, or even the surprising fertility of his inventive genius; but that unswerving truthfulness and honesty which never permit him to hide a weak place, or gloss over a difficulty, but lead him, on all occasions, to point out the weak places in his own armour, and even sometimes, it appears to me, to make admissions against himself which are quite unnecessary. A critic who desires to attack Mr. Darwin has only to read his works with a desire to observe, not their merits, but their defects, and he will find, ready to hand, more adverse suggestions than are likely ever to have suggested themselves to his own sharpness, without Mr. Darwin's self-denying aid. Now this quality of scientific candour is not so common that it needs to be discouraged; and it appears to me to deserve other treatment than that adopted by the Quarterly Reviewer, who deals with Mr. Darwin as an Old Bailey barrister deals with a man against whom he wishes to obtain a conviction, _per fas aut nefas_, and opens his case by endeavouring to create a prejudice against the prisoner in the minds of the jury. In his eagerness to carry out this laudable design, the Quarterly Reviewer cannot even state the history of the doctrine of natural selection without an oblique and entirely unjustifiable attempt to depreciate Mr. Darwin. "To Mr. Darwin," says he, "and (through Mr. Wallace's reticence) to Mr. Darwin alone, is due the credit of having first brought it prominently forward and demonstrated its truth." No one can less desire than I do, to throw a doubt upon Mr. Wallace's originality, or to question his claim to the honour of being one of the originators of the doctrine of natural selection; but the statement that Mr. Darwin has the sole credit of originating the doctrine because of Mr. Wallace's reticence is simply ridiculous. The proof of this is, in the first place, afforded by Mr. Wallace himself, whose noble freedom from petty jealousy in this matter smaller folk would do well to imitate, and who writes thus:--"I have felt all my life, and I still feel, the most sincere satisfaction that Mr. Darwin had been at work long before me and that it was not left for me to attempt to write the 'Origin of Species.' I have long since measured my own strength, and know well that it would be quite unequal to that task." So that if there was any reticence at all in the matter, it was Mr. Darwin's reticence during the long twenty years of study which intervened between the conception and the publication of his theory, which gave Mr. Wallace the chance of being an independent discoverer of the importance of natural selection. And, finally, if it be recollected that Mr. Darwin's and Mr. Wallace's essays were published simultaneously in the "Journal of the Linnæan Society" for 1858, it follows that the Reviewer, while obliquely depreciating Mr. Darwin's deserts, has in reality awarded to him a priority which, in legal strictness, does not exist. Mr. Mivart, whose opinions so often concur with those of the Quarterly Reviewer, puts the case in a way, which I much regret to be obliged to say, is, in my judgment, quite as incorrect; though the injustice may be less glaring. He says that the theory of natural selection is, in general, exclusively associated with the name of Mr. Darwin, "on account of the noble self-abnegation of Mr. Wallace." As I have said, no one can honour Mr. Wallace more than I do, both for what he has done and for what he has not done, in his relation to Mr. Darwin. And perhaps nothing is more creditable to him than his frank declaration that he could not have written such a work as the "Origin of Species." But, by this declaration, the person most directly interested in the matter repudiates, by anticipation, Mr. Mivart's suggestion that Mr. Darwin's eminence is more or less due to Mr. Wallace's modesty. VI EVOLUTION IN BIOLOGY [1878] In the former half of the eighteenth century, the term "evolution" was introduced into biological writings, in order to denote the mode in which some of the most eminent physiologists of that time conceived that the generations of living things took place; in opposition to the hypothesis advocated, in the preceding century, by Harvey in that remarkable work [Footnote: The _Exercitationes de Generatione Animalium_, which Dr. George Ent extracted from him and published in 1651.] which would give him a claim to rank among the founders of biological science, even had he not been the discoverer of the circulation of the blood. One of Harvey's prime objects is to defend and establish, on the basis of direct observation, the opinion already held by Aristotle; that, in the higher animals at any rate, the formation of the new organism by the process of generation takes place, not suddenly, by simultaneous accretion of rudiments of all, or of the most important, of the organs of the adult; nor by sudden metamorphosis of a formative substance into a miniature of the whole, which subsequently grows; but by _epigenesis_, or successive differentiation of a relatively homogeneous rudiment into the parts and structures which are characteristic of the adult. "Et primò, quidem, quoniam per _epigenesin_ sive partium superexorientium additamentum pullum fabricari certum est: quænam pars ante alias omnes exstruatur, et quid de illa ejusque generandi modo observandum veniat, dispiciemus. Ratum sane est et in ovo manifestè apparet quod _Aristoteles_ de perfectorum animalium generatione enuntiat: nimirum, non omnes partes simul fieri, sed ordine aliam post aliam; primùmque existere particulam genitalem, cujus virtute postea (tanquam ex principio quodam) reliquæ omnes partes prosiliant. Qualem in plantarum seminibus (fabis, putà, aut glandibus) gemmam sive apicem protuberantem cernimus, totius futuræ arboris principium. _Estque hæc particula, velut filius emancipatus seorsumquc collocatus, et principium per se vivens; unde postea, membrorum ordo describitur; et quæcunque ad absolvendum animal pertinent, disponuntur._ [Footnote: _De Generatione Animalium_, lib. ii. cap. x.] Quoniam enim _nulla pars se ipsam generat; sed postquam generata est, se ipsam jam auget; ideo eam primùm oriri necesse est, quæ principium augendi contineat (sive enim planta, sive animal est, æque omnibus inest quod vim habeat vegetandi, sive nutriendi_), [Footnote: _De Generatione_, lib. ii. cap. iv.] simulque reliquas omnes partes suo quamque ordine distinguat et formet; proindeque in eadem primogenita particula anima primario inest, sensus, motusque, et totius vitæ auctor et principium." (Exercitatio 51.) Harvey proceeds to contrast this view with that of the "Medici," or followers of Hippocrates and Galen, who, "badly philosophising," imagined that the brain, the heart, and the liver were simultaneously first generated in the form of vesicles; and, at the same time, while expressing his agreement with Aristotle in the principle of epigenesis, he maintains that it is the blood which is the primal generative part, and not, as Aristotle thought, the heart. In the latter part of the seventeenth century, the doctrine of epigenesis, thus advocated by Harvey, was controverted, on the ground of direct observation, by Malpighi, who affirmed that the body of the chick is to be seen in the egg, before the _punctum sanguineum_ makes it appearance. But, from this perfectly correct observation a conclusion which is by no means warranted was drawn; namely, that the chick, as a whole, really exists in the egg antecedently to incubation; and that what happens in the course of the latter process is no addition of new parts, "alias post alias natas," as Harvey puts it, but a simple expansion, or unfolding, of the organs which already exist, though they are too small and inconspicuous to be discovered. The weight of Malpighi's observations therefore fell into the scale of that doctrine which Harvey terms _metamorphosis_, in contradistinction to epigenesis. The views of Malpighi were warmly welcomed, on philosophical grounds, by Leibnitz, [Footnote: "Cependant, pour revenir aux formes ordinaires ou aux âmes matérielles, cette durée qu'il leur faut attribuer à la place de celle qu'on avoit attribuée aux atomes pourroit faire douter si elles ne vont pas de corps en corps; ce qui seroit la métempsychose, à peu près comme quelques philosophes ont cru la transmission du mouvement et celle des espèces. Mais cette imagination est bien éloignée de la nature des choses. Il n'y a point de tel passage; et c'est ici où les transformations de Messieurs Swammerdam, Malpighi, et Leewenhoek, qui sont des plus excellens observateurs de notre tems, sont venues à mon secours, et m'ont fait admettre plus aisément, que l'animal, et toute autre substance organisée ne commence point lorsque nous le croyons, et que sa generation apparente n'est qu'une développement et une espèce d'augmentation. Aussi ai je remarqué que l'auteur de la _Recherche de la Verité_, M. Regis, M. Hartsoeker, et d'autres habiles hommes n'ont pas été fort éloignés de ce sentiment." Leibnitz, _Système Nouveau de la Nature_, 1695. The doctrine of "Embôitement" is contained in the _Considérations sur le Principe de Vie_, 1705; the preface to the _Theodicée_, 1710; and the _Principes de la Nature et de la Grace_ (§ 6), 1718.] who found in them a support to his hypothesis of monads, and by Malebranche; [Footnote: "Il est vrai que la pensée la plus raisonnable et la plus conforme à l'experience sur cette question très difficile de la formation du foetus; c'est que les enfans sont déja presque tout formés avant même l'action par laquelle ils sont conçus; et que leurs mères ne font que leur donner l'accroissement ordinaire dans le temps de la grossesse." _De la Recherche de la Verité_, livre ii. chap. vii. p. 334, 7th ed., 1721.] while, in the middle of the eighteenth century, not only speculative considerations, but a great number of new and interesting observations on the phenomena of generation, led the ingenious Bonnet, and Haller, [Footnote: The writer is indebted to Dr. Allen Thomson for reference to the evidence contained in a note to Haller's edition of Boerhaave's _Prælectiones Academicæ_, vol. v. pt. ii. p. 497, published in 1744, that Haller originally advocated epigenesis.] the first physiologist of the age, to adopt, advocate, and extend them. Bonnet affirms that, before fecundation, the hen's egg contains an excessively minute but complete chick; and that fecundation and incubation simply cause this germ to absorb nutritious matters, which are deposited in the interstices of the elementary structures of which the miniature chick, or germ, is made up. The consequence of this intussusceptive growth is the "development" or "evolution" of the germ into the visible bird. Thus an organised individual (_tout organisé_) "is a composite body consisting of the original, or _elementary_, parts and of the matters which have been associated with them by the aid of nutrition;" so that, if these matters could be extracted from the individual (_tout_), it would, so to speak, become concentrated in a point, and would thus be restored to its primitive condition of a _germ_; "just as by extracting from a bone the calcareous substance which is the source of its hardness, it is reduced to its primitive state of gristle or membrane." [Footnote: _Considérations sur les Corps organisés, chap. x.] "Evolution" and "development" are, for Bonnet, synonymous terms; and since by "evolution" he means simply the expansion of that which was invisible into visibility, he was naturally led to the conclusion, at which Leibnitz had arrived by a different line of reasoning, that no such thing as generation, in the proper sense of the word, exists in Nature. The growth of an organic being is simply a process of enlargement as a particle of dry gelatine may be swelled up by the intussusception of water; its death is a shrinkage, such as the swelled jelly might undergo on desiccation. Nothing really new is produced in the living world, but the germs which develop have existed since the beginning of things; and nothing really dies, but, when what we call death takes place, the living thing shrinks back into its germ state. [Footnote: Bonnet had the courage of his opinions, and in the _Palingénésie Philosophique_, part vi. chap, iv., he develops a hypothesis which he terms "évolution naturelle;" and which, making allowance for his peculiar views of the nature of generation, bears no small resemblance to what is understood by "evolution" at the present day:-- "Si la volonté divine a créé par un seul Acte l'Universalité des êtres, d'où venoient ces plantes et ces animaux dont Moyse nous decrit la Production au troisieme et au cinquieme jour du renouvellement de notre monde? "Abuserois-je de la liberté de conjectures si je disois, que les Plantes et les Animaux qui existent aujourd'hui sont parvenus par une sorte d'evolution naturelle des Etres organises qui peuplaient ce premier Monde, sorti immédiatement des MAINS du CREATEUR?... "Ne supposons que trois révolutions. La Terre vient de sortir des MAINS du CREATEUR. Des causes preparées par sa SAGESSE font développer de toutes parts les Germes. Les Etres organisés commencent à jouir de l'existence. Ils étoient probablement alors bien différens de ce qu'ils sont aujourd'hui. Ils l'etoient autant que ce premier Monde différoit de celui que nous habitons. Nous manquons de moyens pour juger de ces dissemblances, et peut-être que le plus habile Naturaliste qui auroit été placé dans ce premier Monde y auroit entièrement méconnu nos Plantes et nos Animaux."] The two parts of Bonnet's hypothesis, namely, the doctrine that all living things proceed from pre-existing germs, and that these contain, one inclosed within the other, the germs of all future living things, which is the hypothesis of "_emboîtement_;" and the doctrine that every germ contains in miniature all the organs of the adult, which is the hypothesis of evolution or development, in the primary senses of these words, must be carefully distinguished. In fact, while holding firmly by the former, Bonnet more or less modified the latter in his later writings, and, at length, he admits that a "germ" need not be an actual miniature of the organism; but that it may be merely an "original preformation" capable of producing the latter. [Footnote: "Ce mot (germe) ne désignera pas seulement un corps organisé _réduit en petit_; il désignera encore toute espèce de _préformation originelle dont un Tout organique peut résulter comme de son principe immédiat."--Palingénésie Philosophique_, part X. chap. II.] But, thus defined, the germ is neither more nor less than the "particula genitalis" of Aristotle, or the "primordium vegetale" or "ovum" of Harvey; and the "evolution" of such a germ would not be distinguishable from "epigenesis." Supported by the great authority of Haller, the doctrine of evolution, or development, prevailed throughout the whole of the eighteenth century, and Cuvier appears to have substantially adopted Bonnet's later views, though probably he would not have gone all lengths in the direction of "emboîtement." In a well-known note to Laurillard's "Éloge," prefixed to the last edition of the "Ossemens fossiles," the "radical de l'être" is much the same thing as Aristotle's "particula genitalis" and Harvey's "ovum." [Footnote: "M. Cuvier considérant que tous les êtres organisés sont dérivés de parens, et ne voyant dans la nature aucune force capable de produire l'organisation, croyait à la pré-existence des germes; non pas à la pré-existence d'un être tout formé, puisqu'il est bien évident que ce n'est que par des développemens successifs que l'être acquiert sa forme; mais, si l'on peut s'exprimer ainsi, à la pré-existence du _radical de l'être_, radical qui existe avant que la série des évolutions ne commence, et qui remonte certainement, suivant la belle observation de Bonnet, à plusieurs generations."--Laurillard, _Éloge de Cuvier_, note 12.] Bonnet's eminent contemporary, Buffon, held nearly the same views with respect to the nature of the germ, and expresses them even more confidently. "Ceux qui ont cru que le coeur étoit le premier formé, se sont trompés; ceux qui disent que c'est le sang se trompent aussi: tout est formé en même temps. Si l'on ne consulte que l'observation, le poulet se voit dans l'oeuf avant qu'il ait été couvé." [Footnote: _Histoire Naturelle_, tom. ii. ed. ii. 1750, p. 350.] "J'ai ouvert une grande quantité d'oeufs à differens temps avant et après l'incubation, et je me suis convaincu par mes yeux que le poulet existe en entier dans le milieu de la cicatricule au moment qu'il sort du corps de la poule." [Footnote: _Ibid_., p. 351.] The "moule intérieur" of Buffon is the aggregate of elementary parts which constitute the individual, and is thus the equivalent of Bonnet's germ, [Footnote: See particularly Buffon, _l. c._ p. 41.] as defined in the passage cited above. But Buffon further imagined that innumerable "molecules organiques" are dispersed throughout the world, and that alimentation consists in the appropriation by the parts of an organism of those molecules which are analogous to them. Growth, therefore, was, on this hypothesis, a process partly of simple evolution, and partly of what has been termed "syngenesis." Buffon's opinion is, in fact, a sort of combination of views, essentially similar to those of Bonnet, with others, somewhat similar to those of the "Medici" whom Harvey condemns. The "molecules organiques" are physical equivalents of Leibnitz's "monads." It is a striking example of the difficulty of getting people to use their own powers of investigation accurately, that this form of the doctrine of evolution should have held its ground so long; for it was thoroughly and completely exploded, not long after its enunciation, by Casper Friederich Wolff, who in his "Theoria Generationis," published in 1759, placed the opposite theory of epigenesis upon the secure foundation of fact, from which it has never been displaced. But Wolff had no immediate successors. The school of Cuvier was lamentably deficient in embryologists; and it was only in the course of the first thirty years of the present century, that Prévost and Dumas in France, and, later on, Döllinger, Pander, Von Bär, Rathke, and Remak in Germany, founded modern embryology; while, at the same time, they proved the utter incompatibility of the hypothesis of evolution, as formulated by Bonnet and Haller, with easily demonstrable facts. Nevertheless, though the conceptions originally denoted by "evolution" and "development" were shown to be untenable, the words retained their application to the process by which the embryos of living beings gradually make their appearance; and the terms "Development," "Entwickelung," and "Evolutio," are now indiscriminately used for the series of genetic changes exhibited by living beings, by writers who would emphatically deny that "Development" or "Entwickelung" or "Evolutio," in the sense in which these words were usually employed by Bonnet or by Haller, ever occurs. Evolution, or development, is, in fact, at present employed in biology as a general name for the history of the steps by which any living being has acquired the morphological and the physiological characters which distinguish it. As civil history may be divided into biography, which is the history of individuals, and universal history, which is the history of the human race, so evolution falls naturally into two categories--the evolution of the individual, and the evolution of the sum of living beings. It will be convenient to deal with the modern doctrine of evolution under these two heads. I. _The Evolution of the Individual_. No exception is at this time, known to the general law, established upon an immense multitude of direct observations, that every living thing is evolved from a particle of matter in which no trace of the distinctive characters of the adult form of that living thing is discernible. This particle is termed a _germ_. Harvey [Footnote: _Execitationes de Generatione_. Ex. 62, "Ovum esse primordium commune omnibus animalibus."] says-- "Omnibus viventibus primordium insit, ex quo et a quo proveniant. Liceat hoc nobis _primordium vegetale_ nominare; nempe substantiam quandam corpoream vitam habentem potentiâ; vel quoddam per se existens, quod aptum sit, in vegetativam formam, ab interno principio operante, mutari. Quale nempe primordium, ovum est et plantarum semen; tale etiam viviparorum conceptus, et insectorum _vermis_ ab Aristotele dictus: diversa scilicet diversorum viventium primordia." The definition of a germ as "matter potentially alive, and having within itself the tendency to assume a definite living form," appears to meet all the requirements of modern science. For, notwithstanding it might be justly questioned whether a germ is not merely potentially, but rather actually, alive, though its vital manifestations are reduced to a minimum, the term "potential" may fairly be used in a sense broad enough to escape the objection. And the qualification of "potential" has the advantage of reminding us that the great characteristic of the germ is not so much what it is, but what it may, under suitable conditions, become. Harvey shared the belief of Aristotle--whose writings he so often quotes and of whom he speaks as his precursor and model, with the generous respect with which one genuine worker should regard another--that such germs may arise by a process of "equivocal generation" out of not-living matter; and the aphorism so commonly ascribed to him, "_omne vivum ex ovo_" and which is indeed a fair summary of his reiterated assertions, though incessantly employed against the modern advocates of spontaneous generation, can be honestly so used only by those who have never read a score of pages of the "Exercitationes." Harvey, in fact, believed as implicitly as Aristotle did in the equivocal generation of the lower animals. But, while the course of modern investigation has only brought out into greater prominence the accuracy of Harvey's conception of the nature and mode of development of germs, it has as distinctly tended to disprove the occurrence of equivocal generation, or abiogenesis, in the present course of nature. In the immense majority of both plants and animals, it is certain that the germ is not merely a body in which life is dormant or potential, but that it is itself simply a detached portion of the substance of a pre-existing living body; and the evidence has yet to be adduced which will satisfy any cautious reasoner that "omne vivum ex vivo" is not as well-established a law of the existing course of nature as "omne vivum ex ovo." In all instances which have yet been investigated, the substance of this germ has a peculiar chemical composition, consisting of at fewest four elementary bodies, viz., carbon, hydrogen, oxygen, and nitrogen, united into the ill-defined compound known as protein, and associated with much water, and very generally, if not always, with sulphur and phosphorus in minute proportions. Moreover, up to the present time, protein is known only as a product and constituent of living matter. Again, a true germ is either devoid of any structure discernible by optical means, or, at most, it is a simple nucleated cell. [Footnote: In some cases of sexless multiplication the germ is a cell-aggregate--if we call germ only that which is already detached from the parent organism.] In all cases the process of evolution consists in a succession of changes of the form, structure, and functions of the germ, by which it passes, step by step, from an extreme simplicity, or relative homogeneity, of visible structure, to a greater or less degree of complexity or heterogeneity; and the course of progressive differentiation is usually accompanied by growth, which is effected by intussusception. This intussusception, however, is a very different process from that imagined either by Buffon or by Bonnet. The substance by the addition of which the germ is enlarged is in no case simply absorbed, ready-made, from the not-living world and packed between the elementary constituents of the germ, as Bonnet imagined; still less does it consist of the "molecules organiques" of Buffon. The new material is, in great measure, not only absorbed but assimilated, so that it becomes part and parcel of the molecular structure of the living body into which it enters. And, so far from the fully developed organism being simply the germ _plus_ the nutriment which it has absorbed, it is probable that the adult contains neither in form, nor in substance, more than an inappreciable fraction of the constituents of the germ, and that it is almost, if not wholly, made up of assimilated and metamorphosed nutriment. In the great majority of cases, at any rate, the full-grown organism becomes what it is by the absorption of not-living matter, and its conversion into living matter of a specific type. As Harvey says (Ex. 45), all parts of the body are nourished "ab eodem succo alibili, aliter aliterque cambiato," "ut plantæ omnes ex eodem communi nutrimento (sive rore seu terræ humore)." In all animals and plants above the lowest the germ is a nucleated cell, using that term in its broadest sense; and the first step in the process of the evolution of the individual is the division of this cell into two or more portions. The process of division is repeated, until the organism, from being unicellular, becomes multicellular. The single cell becomes a cell-aggregate; and it is to the growth and metamorphosis of the cells of the cell-aggregate thus produced, that all the organs and tissues of the adult owe their origin. In certain animals belonging to every one of the chief groups into which the _Metazoa_ are divisible, the cells of the cell-aggregate which results from the process of yelk-division, and which is termed a _morula_, diverge from one another in such a manner as to give rise to a central space, around which they dispose themselves as a coat or envelope; and thus the morula becomes a vesicle filled with fluid, the _planula_. The wall of the planula is next pushed in on one side, or invaginated, whereby it is converted into a double-walled sac with an opening, the _blastopore_, which leads into the cavity lined by the inner wall. This cavity is the primitive alimentary cavity or _archenteron_; the inner or invaginated layer is the _hypoblast_; the outer the _epiblast_; and the embryo, in this stage, is termed a _gastrula_. In all the higher animals a layer of cells makes its appearance between the hypoblast and the epiblast, and is termed the _mesoblast_. In the further course of development the epiblast becomes the ectoderm or epidermic layer of the body; the hypoblast becomes the epithelium of the middle portion of the alimentary canal; and the mesoblast gives rise to all the other tissues, except the central nervous system, which originates from an ingrowth of the epiblast. With more or less modification in detail, the embryo has been observed to pass through these successive evolutional stages in sundry Sponges, Coelenterates, Worms, Echinoderms, Tunicates, Arthropods, Mollusks, and Vertebrates; and there are valid reasons for the belief that all animals of higher organisation than the _Protozoa_, agree in the general character of the early stages of their individual evolution. Each, starting from the condition of a simple nucleated cell, becomes a cell-aggregate; and this passes through a condition which represents the gastrula stage, before taking on the features distinctive of the group to which it belongs. Stated in this form, the "gastræa theory" of Haeckel appears to the present writer to be one of most important and best founded of recent generalisations. So far as individual plants and animals are concerned, therefore, evolution is not a speculation but a fact; and it takes place by epigenesis. "Animal...per _epigenesin_ procreatur, materiam simul attrahit, parat, concoquit, et eâdem utitur; formatur simul et augetur ... primum futuri corporis concrementum ... prout augetur, dividitur sensim et distinguitur in partes, non simul omnes, sed alias post alias natas, et ordine quasque suo emergentes." [Footnote: Harvey, _Exercitationes de Generatione_. Ex. 45, "Quænam sit pulli materia et quomodo fiat in Ovo."] In these words, by the divination of genius, Harvey, in the seventeenth century, summed up the outcome of the work of all those who, with appliances he could not dream of, are continuing his labours in the nineteenth century. Nevertheless, though the doctrine of epigenesis, as understood by Harvey, has definitively triumphed over the doctrine of evolution, as understood by his opponents of the eighteenth century, it is not impossible that, when the analysis of the process of development is carried still further, and the origin of the molecular components of the physically gross, though sensibly minute, bodies which we term germs is traced, the theory of development will approach more nearly to metamorphosis than to epigenesis. Harvey thought that impregnation influenced the female organism as a contagion; and that the blood, which he conceived to be the first rudiment of the germ, arose in the clear fluid of the "colliquamentum" of the ovum by a process of concrescence, as a sort of living precipitate. We now know, on the contrary, that the female germ or ovum, in all the higher animals and plants, is a body which possesses the structure of a nucleated cell; that impregnation consists in the fusion of the substance [Footnote: [At any rate of the nuclei of the two germ-cells. 1893]] of another more or less modified nucleated cell, the male germ, with the ovum; and that the structural components of the body of the embryo are all derived, by a process of division, from the coalesced male and female germs. Hence it is conceivable, and indeed probable, that every part of the adult contains molecules, derived both from the male and from the female parent; and that, regarded as a mass of molecules, the entire organism may he compared to a web of which the warp is derived from the female and the woof from the male. And each of these may constitute one individuality, in the same sense as the whole organism is one individual, although the matter of the organism has been constantly changing. The primitive male and female molecules may play the part of Buffon's "moules organiques," and mould the assimilated nutriment, each according to its own type, into innumerable new molecules. From this point of view the process, which, in its superficial aspect, is epigenesis, appears in essence, to be evolution, in the modified sense adopted in Bonnet's later writings; and development is merely the expansion of a potential organism or "original preformation" according to fixed laws. II. _The Evolution of the Sum of Living Beings_. The notion that all the kinds of animals and plants may have come into existence by the growth and modification of primordial germs is as old as speculative thought; but the modern scientific form of the doctrine can be traced historically to the influence of several converging lines of philosophical speculation and of physical observation, none of which go farther back than the seventeenth century. These are:-- 1. The enunciation by Descartes of the conception that the physical universe, whether living or not living, is a mechanism, and that, as such, it is explicable on physical principles. 2. The observation of the gradations of structure, from extreme simplicity to very great complexity, presented by living things, and of the relation of these graduated forms to one another. 3. The observation of the existence of an analogy between the series of gradations presented by the species which compose any great group of animals or plants, and the series of embryonic conditions of the highest members of that group. 4. The observation that large groups of species of widely different habits present the same fundamental plan of structure; and that parts of the same animal or plant, the functions of which are very different, likewise exhibit modifications of a common plan. 5. The observation of the existence of structures, in a rudimentary and apparently useless condition, in one species of a group, which are fully developed and have definite functions in other species of the same group. 6. The observation of the effects of varying conditions in modifying living organisms. 7. The observation of the facts of geographical distribution. 8. The observation of the facts of the geological succession of the forms of life. 1. Notwithstanding the elaborate disguise which fear of the powers that were led Descartes to throw over his real opinions, it is impossible to read the "Principes de la Philosophie" without acquiring the conviction that this great philosopher held that the physical world and all things in it, whether living or not living, have originated by a process of evolution, due to the continuous operation of purely physical causes, out of a primitive relatively formless matter. [Footnote: As Buffon has well said:--"L'idée de ramener l'explication de tous les phénomènes à des principes mecaniques est assurement grande et belle, ce pas est le plus hardi qu'on peut faire en philosophie, et c'est Descartes qui l'a fait."--_l. c._ p. 50.] The following passage is especially instructive:-- "Et tant s'en faut que je veuille que l'on croie toutes les choses que j'écrirai, que même je pretends en proposer ici quelques unes que je crois absolument être fausses; à savoir, je ne doute point quo le monde n'ait été créé au commencement avec autant de perfection qu'il eu a; en sorte que le soleil, la terre, la lune, et les étoiles ont été dès lors; et que la terre n'a pas eu seulement en soi les semences des plantes, mais que les plantes même en ont couvert une partie; et qu' Adam et Eve n'ont pas été créés enfans mais en âge d'hommes parfaits. La religion chrétienne veut que nous le croyons ainsi, et la raison naturelle nous persuade entièrement cette vérité; car si nous considérons la toute puissance de Dieu, nous devons juger que tout ce qu'il a fait a eu dès le commencement toute la perfection qu'il devoit avoir. Mais néanmoins, comme on connôitroit beaucoup mieux quelle a été la nature d'Adam et celle des arbres de Paradis si on avoit examiné comment les enfants se forment peu à peu dans le ventre de leurs mères et comment les plantes sortent de leurs semences, que si on avoit seulement considéré quels ils ont été quand Dieu les a créés: tout de même, nous ferons mieux entendre quelle est généralement la nature de toutes les choses qui sont au monde si nous pouvons imaginer quelques principes qui soient fort intelligibles et fort simples, desquels nous puissions voir clairement que les astres et la terre et enfin tout ce monde visible auroit pu être produit ainsi que de quelques semences (bien que, nous sachions qu'il n'a pas été produit en cette façon) que si nous la decrivions seulement comme il est, ou bien comme nous croyons qu'il a été créé. Et parceque je pense avoir trouvé des principes qui sont tels, je tacherai ici de les expliquer." [Footnote: _Principes de la Philosophie_, Troisième partie, § 45.] If we read between the lines of this singular exhibition of force of one kind and weakness of another, it is clear that Descartes believed that he had divined the mode in which the physical universe had been evolved; and the "Traité de l'Homme," and the essay "Sur les Passions" afford abundant additional evidence that he sought for, and thought he had found, an explanation of the phenomena of physical life by deduction from purely physical laws. Spinoza abounds in the same sense, and is as usual perfectly candid-- "Naturæ leges et regulæ, secundum quas omnia fiunt et ex unis formis in alias mutantur, sunt ubique et semper eadem." [Footnote: _Ethices_, Pars tertia, Præfatio.] Leibnitz's doctrine of continuity necessarily led him in the same direction; and, of the infinite multitude of monads with which he peopled the world, each is supposed to be the focus of an endless process of evolution and involution. In the "Protogæa," xxvi., Leibnitz distinctly suggests the mutability of species-- "Alii mirantur in saxis passim species videri quas vel in orbe cognito, vel saltem in vicinis locis frustra quæras. 'Ita Cornua Ammonis,' quæ ex nautilorum numero habeantur, passim et forma et magnitudine (nam et pedali diametro aliquando reperiuntur) ab omnibus illis naturis discrepare dicunt, quas præbet mare. Sed quis absconditos ejus recessus aut subterraneas abyssos pervestigavit? quam multa nobis animalia antea ignota offert novus orbis? Et credibile est per magnas illas conversiones etiam animalium species plurimum immutatas." Thus, in the end of the seventeenth century, the seed was sown which has, at intervals, brought forth recurrent crops of evolutional hypotheses, based, more or less completely, on general reasonings. Among the earliest of these speculations is that put forward by Benoit de Maillet in his "Telliamed," which, though printed in 1735, was not published until twenty-three years later. Considering that this book was written before the time of Haller, or Bonnet, or Linnæus, or Hutton, it surely deserves more respectful consideration than it usually receives. For De Maillet not only has a definite conception of the plasticity of living things, and of the production of existing species by the modification of their predecessors; but he clearly apprehends the cardinal maxim of modern geological science, that the explanation of the structure of the globe is to be sought in the deductive application to geological phenomena of the principles established inductively by the study of the present course of nature. Somewhat later, Maupertuis [Footnote: _Système de la Nature_. "Essai sur la Formation des Corps Organisés," 1751, xiv.] suggested a curious hypothesis as to the causes of variation, which he thinks may be sufficient to account for the origin of all animals from a single pair. Robinet [Footnote: _Considérations Philosophiques sur la gradation naturelle des formes de l'être; ou les essais de la nature qui apprend a faire l'homme,_ 1768.] followed out much the same line of thought as De Maillet, but less soberly; and Bonnet's speculations in the "Palingénésie," which appeared in 1769, have already been mentioned. Buffon (1753-1778), at first a partisan of the absolute immutability of species, subsequently appears to have believed that larger or smaller groups of species have been produced by the modification of a primitive stock; but he contributed nothing to the general doctrine of evolution. Erasmus Darwin ("Zoonomia," 1794), though a zealous evolutionist, can hardly be said to have made any real advance on his predecessors; and, notwithstanding that Goethe (1791-4) had the advantage of a wide knowledge of morphological facts, and a true insight into their signification, while he threw all the power of a great poet into the expression of his conceptions, it may be questioned whether he supplied the doctrine of evolution with a firmer scientific basis than it already possessed. Moreover, whatever the value of Goethe's labours in that field, they were not published before 1820, long after evolutionism had taken a new departure from the works of Treviranus and Lamarck--the first of its advocates who were equipped for their task with the needful large and accurate knowledge of the phenomena of life, as a whole. It is remarkable that each of these writers seems to have been led, independently and contemporaneously, to invent the same name of "Biology" for the science of the phenomena of life; and thus, following Buffon, to have recognised the essential unity of these phenomena, and their contradistinction from those of inanimate nature. And it is hard to say whether Lamarck or Treviranus has the priority in propounding the main thesis of the doctrine of evolution; for though the first volume of Treviranus's "Biologie" appeared only in 1802, he says, in the preface to his later work, the "Erscheinungen und Gesetze des organischen Lebens," dated 1831, that he wrote the first volume of the "Biologie" "nearly five-and-thirty years ago," or about 1796. Now, in 1794, there is evidence that Lamarck held doctrines which present a striking contrast to those which are to be found in the "Philosophie Zoologique," as the following passages show:-- "685. Quoique mon unique objet dans cet article n'ait été que de traiter de la cause physique de l'entretien de la vie des êtres organiques, malgré cela j'ai osé avancer en débutant, que l'existence de ces êtres étonnants n'appartiennent nullement à la nature; que tout ce qu'on peut entendre par le mot _nature_, ne pouvoit donner la vie, c'est-à-dire, que toutes les qualités de la matière, jointes à toutes les circonstances possibles, et même à l'activité répandue dans l'univers, ne pouvaient point produire un être muni du mouvement organique, capable de reproduire son semblable, et sujet à la mort. "686. Tous les individus de cette nature, qui existent, proviennent d'individus semblables qui tous ensemble constituent l'espèce entière. Or, je crois qu'il est aussi impossible à l'homme de connôitre la cause physique du premier individu de chaque espèce, que d'assigner aussi physiquement la cause de l'existence de la matière ou de l'univers entier. C'est au moins ce que le résultat de mes connaissances et de mes réflexions me portent à penser. S'il existe beaucoup de variétés produites par l'effet des circonstances, ces variétés ne denaturent point les espèces; mais on se trompe, sans doute souvent, en indiquant comme espèce, ce qui n'est que variété; et alors je sens que cette erreur peut tirer à conséquence dans les raisonnements que l'on fait sur cette matière." [Footnote: _Recherches sur les causes des principaux faits physiques_, par J.B. Lamarck. Paris. Seconde année de la République. In the preface, Lamarck says that the work was written in 1776, and presented to the Academy in 1780; but it was not published before 17994, and, at that time, it presumably expressed Lamarck's mature views. It would be interesting to know what brought about the change of opinion manifested in the _Recherches sur l'organisation des corps vivants_, published only seven years later.] The first three volumes of Treviranus's "Biologie," which contain his general views of evolution, appeared between 1802 and 1805. The "Recherches sur l'organisation des corps vivants," in which the outlines of Lamarck's doctrines are given, was published in 1802, but the full development of his views, in the "Philosophie Zoologique," did not take place until 1809. The "Biologie" and the "Philosophie Zoologique" are both very remarkable productions, and are still worthy of attentive study, but they fell upon evil times. The vast authority of Cuvier was employed in support of the traditionally respectable hypotheses of special creation and of catastrophism; and the wild speculations of the "Discours sur les Révolutions de la Surface du Globe" were held to be models of sound scientific thinking, while the really much more sober and philosophical hypotheses of the "Hydrogeologie" were scouted. For many years it was the fashion to speak of Lamarck with ridicule, while Treviranus was altogether ignored. Nevertheless, the work had been done. The conception of evolution was henceforward irrepressible, and it incessantly reappears, in one shape or another, [Footnote: See the "Historical Sketch" prefixed to the last edition of the _Origin of Species_.] up to the year 1858, when Mr. Darwin and Mr. Wallace published their "Theory of Natural Selection." The "Origin of Species" appeared in 1859; and it is within the knowledge of all whose memories go back to that time, that, henceforward, the doctrine of evolution has assumed a position and acquired an importance which it never before possessed. In the "Origin of Species," and in his other numerous and important contributions to the solution of the problem of biological evolution, Mr. Darwin confines himself to the discussion of the causes which have brought about the present condition of living matter, assuming such matter to have once come into existence. On the other hand, Mr. Spencer [Footnote: _First Principles_. and _Principles of Biology_, 1860-1864.] and Professor Haeckel [Footnote: _Generelle Marphologie_, 1866.] have dealt with the whole problem of evolution. The profound and vigorous writings of Mr. Spencer embody the spirit of Descartes in the knowledge of our own day, and may be regarded as the "Principes de la Philosophie" of the nineteenth century; while, whatever hesitation may not unfrequently be felt by less daring minds, in following Haeckel in many of his speculations, his attempt to systematise the doctrine of evolution and to exhibit its influence as the central thought of modern biology, cannot fail to have a far-reaching influence on the progress of science. If we seek for the reason of the difference between the scientific position of the doctrine of evolution a century ago, and that which it occupies now, we shall find it in the great accumulation of facts, the several classes of which have been enumerated above, under the second to the eighth heads. For those which are grouped under the second to the seventh of these classes, respectively, have a clear significance on the hypothesis of evolution, while they are unintelligible if that hypothesis be denied. And those of the eighth group are not only unintelligible without the assumption of evolution, but can be proved never to be discordant with that hypothesis, while, in some cases, they are exactly such as the hypothesis requires. The demonstration of these assertions would require a volume, but the general nature of the evidence on which they rest may be briefly indicated. 2. The accurate investigation of the lowest forms of animal life, commenced by Leeuwenhoek and Swammerdam, and continued by the remarkable labours of Reaumur, Trembley, Bonnet, and a host of other observers, in the latter part of the seventeenth and the first half of the eighteenth centuries, drew the attention of biologists to the gradation in the complexity of organisation which is presented by living beings, and culminated in the doctrine of the "échelle des êtres," so powerfully and clearly stated by Bonnet; and, before him, adumbrated by Locke and by Leibnitz. In the then state of knowledge, it appeared that all the species of animals and plants could be arranged in one series; in such a manner that, by insensible gradations, the mineral passed into the plant, the plant into the polype, the polype into the worm, and so, through gradually higher forms of life, to man, at the summit of the animated world. But, as knowledge advanced, this conception ceased to be tenable in the crude form in which it was first put forward. Taking into account existing animals and plants alone, it became obvious that they fell into groups which were more or less sharply separated from one another; and, moreover, that even the species of a genus can hardly ever be arranged in linear series. Their natural resemblances and differences are only to be expressed by disposing them as if they were branches springing from a common hypothetical centre. Lamarck, while affirming the verbal proposition that animals form a single series, was forced by his vast acquaintance with the details of zoology to limit the assertion to such a series as may be formed out of the abstractions constituted by the common characters of each group. [Footnote: "Il s'agit donc de prouver que la série qui constitue l'échelle animale réside essentiellement dans la distribution des masses principales qui la composent et non dans celle des espèces ni même toujours dans celle des genres."--_Philosophie Zoologique_. chap. v.] Cuvier on anatomical, and Von Baer on embryological grounds, made the further step of proving that, even in this limited sense, animals cannot be arranged in a single series, but that there are several distinct plans of organisation to be observed among them, no one of which, in its highest and most complicated modification, leads to any of the others. The conclusions enunciated by Cuvier and Von Baer have been confirmed, in principle, by all subsequent research into the structure of animals and plants. But the effect of the adoption of these conclusions has been rather to substitute a new metaphor for that of Bonnet than to abolish the conception expressed by it. Instead of regarding living things as capable of arrangement in one series like the steps of a ladder, the results of modern investigation compel us to dispose them as if they were the twigs and branches of a tree. The ends of the twigs represent individuals, the smallest groups of twigs species, larger groups genera, and so on, until we arrive at the source of all these ramifications of the main branch, which is represented by a common plan of structure. At the present moment, it is impossible to draw up any definition, based on broad anatomical or developmental characters, by which any one of Cuvier's great groups shall be separated from all the rest. On the contrary, the lower members of each tend to converge towards the lower members of all the others. The same may be said of the vegetable world. The apparently clear distinction between flowering and flowerless plants has been broken down by the series of gradations between the two exhibited by the _Lycopodiaceæ, Rhizocarpeæ_, and _Gymnospermeæ_. The groups of _Fungi_, _Lichenes_, and _Algæ_ have completely run into one another, and, when the lowest forms of each are alone considered, even the animal and vegetable kingdoms cease to have a definite frontier. If it is permissible to speak of the relations of living forms to one another metaphorically, the similitude chosen must undoubtedly be that of a common root, whence two main trunks, one representing the vegetable and one the animal world, spring; and, each dividing into a few main branches, these subdivide into multitudes of branchlets and these into smaller groups of twigs. As Lamarck has well said--[Footnote: _Philosophie Zoologique_, première partie, chap. iii.] "Il n'y a que ceux qui se sont longtemps et fortement occupés de la détermination des espèces, et qui ont consulté de riches collections, qui peuvent savoir jusqu'à quel point les _espèces_, parmi les corps vivants se fondent les unes dans les autres, et qui ont pu se convaincre que, dans les parties où nous voyons des _espèces_ isolès, cela n'est ainsi que parcequ'il nous en manque d'autres qui en sont plus voisines et que nous n'avons pas encore recueillies. "Je ne veux pas dire pour cela que les animaux qui existent forment une série très-simple et partout également nuancée; mais je dis qu'ils forment une série ramense, irréguliérement graduée et qui n'a point de discontinuité dans ses parties, ou qui, du moins, n'en a toujours pas eu, s'il est vrai que, par suite de quelques espèces perdues, il s'en trouve quelque part. Il en resulte que les _espèces_ qui terminent chaque rameau de la série générale tiennent, au moins d'un côté, à d'autres espèces voisines qui se nuancent avec elles. Voilà ce que l'état bien connu des choses me met maintenant à portée de demontrer. Je n'ai besoin d'aucune hypothèse ni d'aucune supposition pour cela: j'en atteste tous les naturalistes observateurs." 3. In a remarkable essay [Footnote: "Entwurf einer Darstellung der zwischen dem Embryozustände der höheren Thiere und dem permanenten der niederen stattfindenden Parallele," _Beyträge zur Vergleichenden Anatomie_, Bd. ii. 1811.] Meckel remarks-- "There is no good physiologist who has not been struck by the observation that the original form of all organisms is one and the same, and that out of this one form, all, the lowest as well as the highest, are developed in such a manner that the latter pass through the permanent forms of the former as transitory stages. Aristotle, Haller, Harvey, Kielmeyer, Autenrieth, and many others, have either made this observation incidentally, or, especially the latter, have drawn particular attention to it, and deduced therefrom results of permanent importance for physiology." Meckel proceeds to exemplify the thesis, that the lower forms of animals represent stages in the course of the development of the higher, with a large series of illustrations. After comparing the Salamanders and the perennibranchiate _Urodela_ with the Tadpoles and the Frogs, and enunciating the law that the more highly any animal is organised the more quickly does it pass through the lower stages, Meckel goes on to say-- "From these lowest Vertebrata to the highest, and to the highest forms among these, the comparison between the embryonic conditions of the higher animals and the adult states of the lower can be more completely and thoroughly instituted than if the survey is extended to the Invertebrata, inasmuch as the latter are in many respects constructed upon an altogether too dissimilar type; indeed they often differ from one another far more than the lowest vertebrate does from the highest mammal; yet the following pages will show that the comparison may also be extended to them with interest. In fact, there is a period when, as Aristotle long ago said, the embryo of the highest animal has the form of a mere worm; and, devoid of internal and external organisation, is merely an almost structureless lump of polype substance. Notwithstanding the origin of organs, it still for a certain time, by reason of its want of an internal bony skeleton, remains worm and mollusk, and only later enters into the series of the Vertebrata, although traces of the vertebral column even in the earliest periods testify its claim to a place in that series."--_Op, cit_ pp. 4, 5. If Meckel's proposition is so far qualified, that the comparison of adult with embryonic forms is restricted within the limits of one type of organisation; and, if it is further recollected that the resemblance between the permanent lower form and the embryonic stage of a higher form is not special but general, it is in entire accordance with modern embryology; although there is no branch of biology which has grown so largely, and improved its methods so much, since Meckel's time, as this. In its original form, the doctrine of "arrest of development," as advocated by Geoffroy Saint-Hilaire and Serres, was no doubt an overstatement of the case. It is not true, for example, that a fish is a reptile arrested in its development, or that a reptile was ever a fish: but it is true that the reptile embryo, at one stage of its development, is an organism which, if it had an independent existence, must be classified among fishes; and all the organs of the reptile pass, in the course of their development, through conditions which are closely analogous to those which are permanent in some fishes. 4. That branch of biology which is termed Morphology is a commentary upon, and expansion of, the proposition that widely different animals or plants, and widely different parts of animals or plants, are constructed upon the same plan. From the rough comparison of the skeleton of a bird with that of a man by Belon, in the sixteenth century (to go no farther back), down to the theory of the limbs and the theory of the skull at the present day; or, from the first demonstration of the homologies of the parts of a flower by C. F. Wolff, to the present elaborate analysis of the floral organs, morphology exhibits a continual advance towards the demonstration of a fundamental unity among the seeming diversities of living structures. And this demonstration has been completed by the final establishment of the cell theory, which involves the admission of a primitive conformity, not only of all the elementary structures in animals and plants respectively, but of those in the one of these great divisions of living things with those in the other. No _à priori_ difficulty can be said to stand in the way of evolution, when it can be shown that all animals and all plants proceed by modes of development, which are similar in principle, from a fundamental protoplasmic material. 5. The innumerable cases of structures, which are rudimentary and apparently useless, in species, the close allies of which possess well-developed and functionally important homologous structures, are readily intelligible on the theory of evolution, while it is hard to conceive their _raison d'être_ on any other hypothesis. However, a cautious reasoner will probably rather explain such cases deductively from the doctrine of evolution than endeavour to support the doctrine of evolution by them. For it is almost impossible to prove that any structure, however rudimentary, is useless--that is to say, that it plays no part whatever in the economy; and, if it is in the slightest degree useful, there is no reason why, on the hypothesis of direct creation, it should not have been created. Nevertheless, double-edged as is the argument from rudimentary organs, there is probably none which has produced a greater effect in promoting the general acceptance of the theory of evolution. 6. The older advocates of evolution sought for the causes of the process exclusively in the influence of varying conditions, such as climate and station, or hybridisation, upon living forms. Even Treviranus has got no farther than this point. Lamarck introduced the conception of the action of an animal on itself as a factor in producing modification. Starting from the well-known fact that the habitual use of a limb tends to develop the muscles of the limb, and to produce a greater and greater facility in using it, he made the general assumption that the effort of an animal to exert an organ in a given direction tends to develop the organ in that direction. But a little consideration showed that, though Lamarck had seized what, as far it goes, is a true cause of modification, it is a cause the actual effects of which are wholly inadequate to account for any considerable modification in animals, and which can have no influence at all in the vegetable world; and probably nothing contributed so much to discredit evolution, in the early part of this century, as the floods of easy ridicule which were poured upon this part of Lamarck's speculation. The theory of natural selection, or survival of the fittest, was suggested by Wells in 1813, and further elaborated by Matthew in 1831. But the pregnant suggestions of these writers remained practically unnoticed and forgotten, until the theory was independently devised and promulgated by Darwin and Wallace in 1858, and the effect of its publication was immediate and profound. Those who were unwilling to accept evolution, without better grounds than such as are offered by Lamarck, or the author of that particularly unsatisfactory book, the "Vestiges of the Natural History of the Creation," and who therefore preferred to suspend their judgment on the question, found in the principle of selective breeding, pursued in all its applications with marvellous knowledge and skill by Mr. Darwin, a valid explanation of the occurrence of varieties and races; and they saw clearly that, if the explanation would apply to species, it would not only solve the problem of their evolution, but that it would account for the facts of teleology, as well as for those of morphology; and for the persistence of some forms of life unchanged through long epochs of time, while others undergo comparatively rapid metamorphosis. How far "natural selection" suffices for the production of species remains to be seen. Few can doubt that, if not the whole cause, it is a very important factor in that operation; and that it must play a great part in the sorting out of varieties into those which are transitory and those which are permanent. But the causes and conditions of variation have yet to be thoroughly explored; and the importance of natural selection will not be impaired, even if further inquiries should prove that variability is definite, and is determined in certain directions rather than in others, by conditions inherent in that which varies. It is quite conceivable that every species tends to produce varieties of a limited number and kind, and that the effect of natural selection is to favour the development of some of these, while it opposes the development of others along their predetermined lines of modification. 7. No truths brought to light by biological investigation were better calculated to inspire distrust of the dogmas intruded upon science in the name of theology, than those which relate to the distribution of animals and plants on the surface of the earth. Very skilful accommodation was needful, if the limitation of sloths to South America, and of the ornithorhynchus to Australia, was to be reconciled with the literal interpretation of the history of the deluge; and with the establishment of the existence of distinct provinces of distribution, any serious belief in the peopling of the world by migration from Mount Ararat came to an end. Under these circumstances, only one alternative was left for those who denied the occurrence of evolution--namely, the supposition that the characteristic animals and plants of each great province were created as such, within the limits in which we find them. And as the hypothesis of "specific centres," thus formulated, was heterodox from the theological point of view, and unintelligible under its scientific aspect, it may be passed over without further notice, as a phase of transition from the creational to the evolutional hypothesis. 8. In fact, the strongest and most conclusive arguments in favour of evolution are those which are based upon the facts of geographical, taken in conjunction with those of geological, distribution. Both Mr. Darwin and Mr. Wallace lay great stress on the close relation which obtains between the existing fauna of any region and that of the immediately antecedent geological epoch in the same region; and rightly, for it is in truth inconceivable that there should be no genetic connection between the two. It is possible to put into words the proposition that all the animals and plants of each geological epoch were annihilated and that a new set of very similar forms was created for the next epoch; but it may be doubted if any one who ever tried to form a distinct mental image of this process of spontaneous generation on the grandest scale, ever really succeeded in realising it. Within the last twenty years, the attention of the best palæontologists has been withdrawn from the hodman's work of making "new species" of fossils, to the scientific task of completing our knowledge of individual species, and tracing out the succession of the forms presented by any given type in time. Those who desire to inform themselves of the nature and extent of the evidence bearing on these questions may consult the works of Rütimeyer, Gaudry, Kowalewsky, Marsh, and the writer of the present article. It must suffice, in this place, to say that the successive forms of the Equine type have been fully worked out; while those of nearly all the other existing types of Ungulate mammals and of the _Carnivora_ have been almost as closely followed through the Tertiary deposits; the gradations between birds and reptiles have been traced; and the modifications undergone by the _Crocodilia_, from the Triassic epoch to the present day, have been demonstrated. On the evidence of palæontology, the evolution of many existing forms of animal life from their predecessors is no longer an hypothesis, but an historical fact; it is only the nature of the physiological factors to which that evolution is due which is still open to discussion. [At page 209, the reference to Erasmus Darwin does not do justice to that ingenious writer, who, in the 39th section of the _Zoonomia_, clearly and repeatedly enunciates the theory of the inheritance of acquired modifications. For example "From their first rudiment, or primordium, to the termination of their lives, all animals undergo perpetual transformations; which are in part produced by their own exertions in consequence of their desires and aversions, of their pleasures and their pains, or of irritation, or of associations; and many of these acquired forms or propensities are transmitted to their posterity." _Zoonomia_ I., p. 506. 1893.] VII THE COMING OF AGE OF "THE ORIGIN OF SPECIES" [1880] Many of you will be familiar with the aspect of this small green-covered book. It is a copy of the first edition of the "Origin of Species," and bears the date of its production--the 1st of October 1859. Only a few months, therefore, are needed to complete the full tale of twenty-one years since its birthday. Those whose memories carry them back to this time will remember that the infant was remarkably lively, and that a great number of excellent persons mistook its manifestations of a vigorous individuality for mere naughtiness; in fact there was a very pretty turmoil about its cradle. My recollections of the period are particularly vivid, for, having conceived a tender affection for a child of what appeared to me to be such remarkable promise, I acted for some time in the capacity of a sort of under-nurse, and thus came in for my share of the storms which threatened the very life of the young creature. For some years it was undoubtedly warm work; but considering how exceedingly unpleasant the apparition of the newcomer must have been to those who did not fall in love with him at first sight, I think it is to the credit of our age that the war was not fiercer, and that the more bitter and unscrupulous forms of opposition died away as soon as they did. I speak of this period as of something past and gone, possessing merely an historical, I had almost said an antiquarian interest. For, during the second decade of the existence of the "Origin of Species," opposition, though by no means dead, assumed a different aspect. On the part of all those who had any reason to respect themselves, it assumed a thoroughly respectful character. By this time, the dullest began to perceive that the child was not likely to perish of any congenital weakness or infantile disorder, but was growing into a stalwart personage, upon whom mere goody scoldings and threatenings with the birch-rod were quite thrown away. In fact, those who have watched the progress of science within the last ten years will bear me out to the full, when I assert that there is no field of biological inquiry in which the influence of the "Origin of Species" is not traceable; the foremost men of science in every country are either avowed champions of its leading doctrines, or at any rate abstain from opposing them; a host of young and ardent investigators seek for and find inspiration and guidance in Mr. Darwin's great work; and the general doctrine of evolution, to one side of which it gives expression, obtains, in the phenomena of biology, a firm base of operations whence it may conduct its conquest of the whole realm of Nature. History warns us, however, that it is the customary fate of new truths to begin as heresies and to end as superstitions; and, as matters now stand, it is hardly rash to anticipate that, in another twenty years, the new generation, educated under the influences of the present day, will be in danger of accepting the main doctrines of the "Origin of Species," with as little reflection, and it may be with as little justification, as so many of our contemporaries, twenty years ago, rejected them. Against any such a consummation let us all devoutly pray; for the scientific spirit is of more value than its products, and irrationally held truths may be more harmful than reasoned errors. Now the essence of the scientific spirit is criticism. It tells us that whenever a doctrine claims our assent we should reply, Take it if you can compel it. The struggle for existence holds as much in the intellectual as in the physical world. A theory is a species of thinking, and its right to exist is coextensive with its power of resisting extinction by its rivals. From this point of view, it appears to me that it would be but a poor way of celebrating the Coming of Age of the "Origin of Species," were I merely to dwell upon the facts, undoubted and remarkable as they are, of its far-reaching influence and of the great following of ardent disciples who are occupied in spreading and developing its doctrines. Mere insanities and inanities have before now swollen to portentous size in the course of twenty years. Let us rather ask this prodigious change in opinion to justify itself: let us inquire whether anything has happened since 1859, which will explain, on rational grounds, why so many are worshipping that which they burned, and burning that which they worshipped. It is only in this way that we shall acquire the means of judging whether the movement we have witnessed is a mere eddy of fashion, or truly one with the irreversible current of intellectual progress, and, like it, safe from retrogressive reaction. Every belief is the product of two factors: the first is the state of the mind to which the evidence in favour of that belief is presented; and the second is the logical cogency of the evidence itself. In both these respects, the history of biological science during the last twenty years appears to me to afford an ample explanation of the change which has taken place; and a brief consideration of the salient events of that history will enable us to understand why, if the "Origin of Species" appeared now, it would meet with a very different reception from that which greeted it in 1859. One-and-twenty years ago, in spite of the work commenced by Hutton and continued with rare skill and patience by Lyell, the dominant view of the past history of the earth was catastrophic. Great and sudden physical revolutions, wholesale creations and extinctions of living beings, were the ordinary machinery of the geological epic brought into fashion by the misapplied genius of Cuvier. It was gravely maintained and taught that the end of every geological epoch was signalised by a cataclysm, by which every living being on the globe was swept away, to be replaced by a brand-new creation when the world returned to quiescence. A scheme of nature which appeared to be modelled on the likeness of a succession of rubbers of whist, at the end of each of which the players upset the table and called for a new pack, did not seem to shock anybody. I may be wrong, but I doubt if, at the present time, there is a single responsible representative of these opinions left. The progress of scientific geology has elevated the fundamental principle of uniformitarianism, that the explanation of the past is to be sought in the study of the present, into the position of an axiom; and the wild speculations of the catastrophists, to which we all listened with respect a quarter of a century ago, would hardly find a single patient hearer at the present day. No physical geologist now dreams of seeking, outside the range of known natural causes, for the explanation of anything that happened millions of years ago, any more than he would be guilty of the like absurdity in regard to current events. The effect of this change of opinion upon biological speculation is obvious. For, if there have been no periodical general physical catastrophes, what brought about the assumed general extinctions and re-creations of life which are the corresponding biological catastrophes? And, if no such interruptions of the ordinary course of nature have taken place in the organic, any more than in the inorganic, world, what alternative is there to the admission of evolution? The doctrine of evolution in biology is the necessary result of the logical application of the principles of uniformitarianism to the phenomena of life. Darwin is the natural successor of Hutton and Lyell, and the "Origin of Species" the logical sequence of the "Principles of Geology." The fundamental doctrine of the "Origin of Species," as of all forms of the theory of evolution applied to biology, is "that the innumerable species, genera, and families of organic beings with which the world is peopled have all descended, each within its own class or group, from common parents, and have all been modified in the course of descent." [Footnote: _Origin of Species_, ed. I, p. 457.] And, in view of the facts of geology, it follows that all living animals and plants "are the lineal descendants of those which lived long before the Silurian epoch." [Footnote: _Origin of Species_, p. 458.] It is an obvious consequence of this theory of descent with modification, as it is sometimes called, that all plants and animals, however different they may now be, must, at one time or other, have been connected by direct or indirect intermediate gradations, and that the appearance of isolation presented by various groups of organic beings must be unreal. No part of Mr. Darwin's work ran more directly counter to the prepossessions of naturalists twenty years ago than this. And such prepossessions were very excusable, for there was undoubtedly a great deal to be said, at that time, in favour of the fixity of species and of the existence of great breaks, which there was no obvious or probable means of filling up, between various groups of organic beings. For various reasons, scientific and unscientific, much had been made of the hiatus between man and the rest of the higher mammalia, and it is no wonder that issue was first joined on this part of the controversy. I have no wish to revive past and happily forgotten controversies; but I must state the simple fact that the distinctions in the cerebral and other characters, which were so hotly affirmed to separate man from all other animals in 1860, have all been demonstrated to be non-existent, and that the contrary doctrine is now universally accepted and taught. But there were other cases in which the wide structural gaps asserted to exist between one group of animals and another were by no means fictitious; and, when such structural breaks were real, Mr. Darwin could account for them only by supposing that the intermediate forms which once existed had become extinct. In a remarkable passage he says-- "We may thus account even for the distinctness of whole classes from each other--for instance, of birds from all other vertebrate animals--by the belief that many animal forms of life have been utterly lost, through which the early progenitors of birds were formerly connected with the early progenitors of the other vertebrate classes." [Footnote: _Origin of Species_, p. 431.] Adverse criticism made merry over such suggestions as these. Of course it was easy to get out of the difficulty by supposing extinction; but where was the slightest evidence that such intermediate forms between birds and reptiles as the hypothesis required ever existed? And then probably followed a tirade upon this terrible forsaking of the paths of "Baconian induction." But the progress of knowledge has justified Mr. Darwin to an extent which could hardly have been anticipated. In 1862, the specimen of _Archæopteryx_, which, until the last two or three years, has remained unique, was discovered; and it is an animal which, in its feathers and the greater part of its organisation, is a veritable bird, while, in other parts, it is as distinctly reptilian. In 1868, I had the honour of bringing under your notice, in this theatre, the results of investigations made, up to that time, into the anatomical characters of certain ancient reptiles, which showed the nature of the modifications in virtue of which the type of the quadrupedal reptile passed into that of a bipedal bird; and abundant confirmatory evidence of the justice of the conclusions which I then laid before you has since come to light. In 1875, the discovery of the toothed birds of the cretaceous formation in North America by Professor Marsh completed the series of transitional forms between birds and reptiles, and removed Mr. Darwin's proposition that "many animal forms of life have been utterly lost, through which the early progenitors of birds were formerly connected with the early progenitors of the other vertebrate classes," from the region of hypothesis to that of demonstrable fact. In 1859, there appeared to be a very sharp and clear hiatus between vertebrated and invertebrated animals, not only in their structure, but, what was more important, in their development. I do not think that we even yet know the precise links of connection between the two; but the investigations of Kowalewsky and others upon the development of _Amphioxus_ and of the _Tunicata_ prove, beyond a doubt, that the differences which were supposed to constitute a barrier between the two are non-existent. There is no longer any difficulty in understanding how the vertebrate type may have arisen from the invertebrate, though the full proof of the manner in which the transition was actually effected may still be lacking. Again, in 1859, there appeared to be a no less sharp separation between the two great groups of flowering and flowerless plants. It is only subsequently that the series of remarkable investigations inaugurated by Hofmeister has brought to light the extraordinary and altogether unexpected modifications of the reproductive apparatus in the _Lycopodiaceæ_, the _Rhizocarpeæ_, and the _Gymnospermeæ_, by which the ferns and the mosses are gradually connected with the Phanerogamic division of the vegetable world. So, again, it is only since 1859 that we have acquired that wealth of knowledge of the lowest forms of life which demonstrates the futility of any attempt to separate the lowest plants from the lowest animals, and shows that the two kingdoms of living nature have a common borderland which belongs to both, or to neither. Thus it will be observed that the whole tendency of biological investigation, since 1859, has been in the direction of removing the difficulties which the apparent breaks in the series created at that time; and the recognition of gradation is the first step towards the acceptance of evolution. As another great factor in bringing about the change of opinion which has taken place among naturalists, I count the astonishing progress which has been made in the study of embryology. Twenty years ago, not only were we devoid of any accurate knowledge of the mode of development of many groups of animals and plants, but the methods of investigation were rude and imperfect. At the present time, there is no important group of organic beings the development of which has not been carefully studied; and the modern methods of hardening and section-making enable the embryologist to determine the nature of the process, in each case, with a degree of minuteness and accuracy which is truly astonishing to those whose memories carry them back to the beginnings of modern histology. And the results of these embryological investigations are in complete harmony with the requirements of the doctrine of evolution. The first beginnings of all the higher forms of animal life are similar, and however diverse their adult conditions, they start from a common foundation. Moreover, the process of development of the animal or the plant from its primary egg, or germ, is a true process of evolution--a progress from almost formless to more or less highly organised matter, in virtue of the properties inherent in that matter. To those who are familiar with the process of development, all _a priori_ objections to the doctrine of biological evolution appear childish. Any one who has watched the gradual formation of a complicated animal from the protoplasmic mass, which constitutes the essential element of a frog's or a hen's egg, has had under his eyes sufficient evidence that a similar evolution of the whole animal world from the like foundation is, at any rate, possible. Yet another product of investigation has largely contributed to the removal of the objections to the doctrine of evolution current in 1859. It is the proof afforded by successive discoveries that Mr. Darwin did not over-estimate the imperfection of the geological record. No more striking illustration of this is needed than a comparison of our knowledge of the mammalian fauna of the Tertiary epoch in 1859 with its present condition. M. Gaudry's researches on the fossils of Pikermi were published in 1868, those of Messrs. Leidy, Marsh, and Cope, on the fossils of the Western Territories of America, have appeared almost wholly since 1870, those of M. Filhol on the phosphorites of Quercy in 1878. The general effect of these investigations has been to introduce to us a multitude of extinct animals, the existence of which was previously hardly suspected; just as if zoologists were to become acquainted with a country, hitherto unknown, as rich in novel forms of life as Brazil or South Africa once were to Europeans. Indeed, the fossil fauna of the Western Territories of America bid fair to exceed in interest and importance all other known Tertiary deposits put together; and yet, with the exception of the case of the American tertiaries, these investigations have extended over very limited areas; and, at Pikermi, were confined to an extremely small space. Such appear to me to be the chief events in the history of the progress of knowledge during the last twenty years, which account for the changed feeling with which the doctrine of evolution is at present regarded by those who have followed the advance of biological science, in respect of those problems which bear indirectly upon that doctrine. But all this remains mere secondary evidence. It may remove dissent, but it does not compel assent. Primary and direct evidence in favour of evolution can be furnished only by palæontology. The geological record, so soon as it approaches completeness, must, when properly questioned, yield either an affirmative or a negative answer: if evolution has taken place, there will its mark be left; if it has not taken place, there will lie its refutation. What was the state of matters in 1859? Let us hear Mr. Darwin, who may be trusted always to state the case against himself as strongly as possible. "On this doctrine of the extermination of an infinitude of connecting links between the living and extinct inhabitants of the world, and at each successive period between the extinct and still older species, why is not every geological formation charged with such links? Why does not every collection of fossil remains afford plain evidence of the gradation and mutation of the forms of life? We meet with no such evidence, and this is the most obvious and plausible of the many objections which may be urged against my theory." [Footnote: _Origin of Species_, ed. 1, p. 463.] Nothing could have been more useful to the opposition than this characteristically candid avowal, twisted as it immediately was into an admission that the writer's views were contradicted by the facts of palæontology. But, in fact, Mr. Darwin made no such admission. What he says in effect is, not that palæontological evidence is against him, but that it is not distinctly in his favour; and, without attempting to attenuate the fact, he accounts for it by the scantiness and the imperfection of that evidence. What is the state of the case now, when, as we have seen, the amount of our knowledge respecting the mammalia of the Tertiary epoch is increased fifty-fold, and in some directions even approaches completeness? Simply this, that, if the doctrine of evolution had not existed, palaeontologists must have invented it, so irresistibly is it forced upon the mind by the study of the remains of the Tertiary mammalia which have been brought to light since 1859. Among the fossils of Pikermi, Gaudry found the successive stages by which the ancient civets passed into the more modern hyænas; through the Tertiary deposits of Western America, Marsh tracked the successive forms by which the ancient stock of the horse has passed into its present form; and innumerable less complete indications of the mode of evolution of other groups of the higher mammalia have been obtained. In the remarkable memoir on the phosphorites of Quercy, to which I have referred, M. Filhol describes no fewer than seventeen varieties of the genus _Cynodictis_, which fill up all the interval between the viverine animals and the bear-like dog _Amphicyon_; nor do I know any solid ground of objection to the supposition that, in this _Cynodictis-Amphicyon_ group, we have the stock whence all the Viveridæ, Felidæ, Hyænidæ, Canidæ, and perhaps the Procyonidæ and Ursidæ, of the present fauna have been evolved. On the contrary, there is a great deal to be said in favour. In the course of summing up his results, M. Filhol observes:-- "During the epoch of the phosphorites, great changes took place in animal forms, and almost the same types as those which now exist became defined from one another. "Under the influence of natural conditions of which we have no exact knowledge, though traces of them are discoverable, species have been modified in a thousand ways: races have arisen which, becoming fixed, have thus produced a corresponding number of secondary species." In 1859, language of which this is an unintentional paraphrase, occurring in the "Origin of Species," was scouted as wild speculation; at present, it is a sober statement of the conclusions to which an acute and critically-minded investigator is led by large and patient study of the facts of palæontology. I venture to repeat what I have said before, that so far as the animal world is concerned, evolution is no longer a speculation, but a statement of historical fact. It takes its place alongside of those accepted truths which must be reckoned with by philosophers of all schools. Thus when, on the first day of October next, "The Origin of Species" comes of age, the promise of its youth will be amply fulfilled; and we shall be prepared to congratulate the venerated author of the book, not only that the greatness of his achievement and its enduring influence upon the progress of knowledge have won him a place beside our Harvey; but, still more, that, like Harvey, he has lived long enough to outlast detraction and opposition, and to see the stone that the builders rejected become the head-stone of the corner. VIII CHARLES DARWIN [_Nature_, April 27th, 1882] Very few, even among those who have taken the keenest interest in the progress of the revolution in natural knowledge set afoot by the publication of "The Origin of Species," and who have watched, not without astonishment, the rapid and complete change which has been effected both inside and outside the boundaries of the scientific world in the attitude of men's minds towards the doctrines which are expounded in that great work, can have been prepared for the extraordinary manifestation of affectionate regard for the man, and of profound reverence for the philosopher, which followed the announcement, on Thursday last, of the death of Mr. Darwin. Not only in these islands, where so many have felt the fascination of personal contact with an intellect which had no superior, and with a character which was even nobler than the intellect; but, in all parts of the civilised world, it would seem that those whose business it is to feel the pulse of nations and to know what interests the masses of mankind, were well aware that thousands of their readers would think the world the poorer for Darwin's death, and would dwell with eager interest upon every incident of his history. In France, in Germany, in Austro-Hungary, in Italy, in the United States, writers of all shades of opinion, for once unanimous, have paid a willing tribute to the worth of our great countryman, ignored in life by the official representatives of the kingdom, but laid in death among his peers in Westminster Abbey by the will of the intelligence of the nation. It is not for us to allude to the sacred sorrows of the bereaved home at Down; but it is no secret that, outside that domestic group, there are many to whom Mr. Darwin's death is a wholly irreparable loss. And this not merely because of his wonderfully genial, simple, and generous nature; his cheerful and animated conversation, and the infinite variety and accuracy of his information; but because the more one knew of him, the more he seemed the incorporated ideal of a man of science. Acute as were his reasoning powers, vast as was his knowledge, marvellous as was his tenacious industry, under physical difficulties which would have converted nine men out of ten into aimless invalids; it was not these qualities, great as they were, which impressed those who were admitted to his intimacy with involuntary veneration, but a certain intense and almost passionate honesty by which all his thoughts and actions were irradiated, as by a central fire. It was this rarest and greatest of endowments which kept his vivid imagination and great speculative powers within due bounds; which compelled him to undertake the prodigious labours of original investigation and of reading, upon which his published works are based; which made him accept criticisms and suggestions from anybody and everybody, not only without impatience, but with expressions of gratitude sometimes almost comically in excess of their value; which led him to allow neither himself nor others to be deceived by phrases, and to spare neither time nor pains in order to obtain clear and distinct ideas upon every topic with which he occupied himself. One could not converse with Darwin without being reminded of Socrates. There was the same desire to find some one wiser than himself; the same belief in the sovereignty of reason; the same ready humour; the same sympathetic interest in all the ways and works of men. But instead of turning away from the problems of Nature as hopelessly insoluble, our modern philosopher devoted his whole life to attacking them in the spirit of Heraclitus and of Democritus, with results which are the substance of which their speculations were anticipatory shadows. The due appreciation, or even enumeration, of these results is neither practicable nor desirable at this moment. There is a time for all things--a time for glorying in our ever-extending conquests over the realm of Nature, and a time for mourning over the heroes who have led us to victory. None have fought better, and none have been more fortunate, than Charles Darwin. He found a great truth trodden underfoot, reviled by bigots, and ridiculed by all the world; he lived long enough to see it, chiefly by his own efforts, irrefragably established in science, inseparably incorporated with the common thoughts of men, and only hated and feared by those who would revile, but dare not. What shall a man desire more than this? Once more the image of Socrates rises unbidden, and the noble peroration of the "Apology" rings in our ears as if it were Charles Darwin's farewell:-- "The hour of departure has arrived, and we go our ways--I to die and you to live. Which is the better, God only knows." IX THE DARWIN MEMORIAL [June 9th, 1885] _Address by the President of the Royal Society, in the name of the Memorial Committee, on handing over the statue of Darwin to H.R.H. the Prince of Wales, as representative of the Trustees of the British Museum_. YOUR ROYAL HIGHNESS,--It is now three years since the announcement of the death of our famous countryman, Charles Darwin, gave rise to a manifestation of public feeling, not only in these realms, but throughout the civilised world, which, if I mistake not, is without precedent in the modest annals of scientific biography. The causes of this deep and wide outburst of emotion are not far to seek. We had lost one of these rare ministers and interpreters of Nature whose names mark epochs in the advance of natural knowledge. For, whatever be the ultimate verdict of posterity upon this or that opinion which Mr. Darwin has propounded; whatever adumbrations or anticipations of his doctrines may be found in the writings of his predecessors; the broad fact remains that, since the publication and by reason of the publication, of "The Origin of Species" the fundamental conceptions and the aims of the students of living Nature have been completely changed. From that work has sprung a great renewal, a true "instauratio magna" of the zoological and botanical sciences. But the impulse thus given to scientific thought rapidly spread beyond the ordinarily recognised limits of biology. Psychology, Ethics, Cosmology were stirred to their foundations, and the "Origin of Species" proved itself to be the fixed point which the general doctrine of evolution needed in order to move the world. "Darwinism," in one form or another, sometimes strangely distorted and mutilated, became an everyday topic of men's speech, the object of an abundance both of vituperation and of praise, more often than of serious study. It is curious now to remember how largely, at first, the objectors predominated; but considering the usual fate of new views, it is still more curious to consider for how short a time the phase of vehement opposition lasted. Before twenty years had passed, not only had the importance of Mr. Darwin's work been fully recognised, but the world had discerned the simple, earnest, generous character of the man, that shone through every page of his writings. I imagine that reflections such as these swept through the minds alike of loving friends and of honourable antagonists when Mr. Darwin died; and that they were at one in the desire to honour the memory of the man who, without fear and without reproach, had successfully fought the hardest intellectual battle of these days. It was in satisfaction of these just and generous impulses that our great naturalist's remains were deposited in Westminster Abbey; and that, immediately afterwards, a public meeting, presided over by my lamented predecessor, Mr. Spottiswoode, was held in the rooms of the Royal Society, for the purpose of considering what further step should be taken towards the same end. It was resolved to invite subscriptions, with the view of erecting a statue of Mr. Darwin in some suitable locality; and to devote any surplus to the advancement of the biological sciences. Contributions at once flowed in from Austria, Belgium, Brazil, Denmark, France, Germany, Holland, Italy, Norway, Portugal, Russia, Spain, Sweden, Switzerland, the United States, and the British Colonies, no less than from all parts of the three kingdoms; and they came from all classes of the community. To mention one interesting case, Sweden sent in 2296 subscriptions "from all sorts of people," as the distinguished man of science who transmitted them wrote, "from the bishop to the seamstress, and in sums from five pounds to two pence." The Executive Committee has thus been enabled to carry out the objects proposed. A "Darwin Fund" has been created, which is to be held in trust by the Royal Society, and is to be employed in the promotion of biological research. The execution of the statue was entrusted to Mr. Boehm; and I think that those who had the good fortune to know Mr. Darwin personally will admire the power of artistic divination which has enabled the sculptor to place before us so very characteristic a likeness of one whom he had not seen. It appeared to the Committee that, whether they regarded Mr. Darwin's career or the requirements of a work of art, no site could be so appropriate as this great hall, and they applied to the Trustees of the British Museum for permission to erect it in its present position. That permission was most cordially granted, and I am desired to tender the best thanks of the Committee to the Trustees for their willingness to accede to our wishes. I also beg leave to offer the expression of our gratitude to your Royal Highness for kindly consenting to represent the Trustees to-day. It only remains for me, your Royal Highness, my Lords and Gentlemen, Trustees of the British Museum, in the name of the Darwin Memorial Committee, to request you to accept this statue of Charles Darwin. We do not make this request for the mere sake of perpetuating a memory; for so long as men occupy themselves with the pursuit of truth, the name of Darwin runs no more risk of oblivion than does that of Copernicus, or that of Harvey. Nor, most assuredly, do we ask you to preserve the statue in its cynosural position in this entrance-hall of our National Museum of Natural History as evidence that Mr. Darwin's views have received your official sanction; for science does not recognise such sanctions, and commits suicide when it adopts a creed. No; we beg you to cherish this Memorial as a symbol by which, as generation after generation of students of Nature enter yonder door, they shall be reminded of the ideal according to which they must shape their lives, if they would turn to the best account the opportunities offered by the great institution under your charge. X OBITUARY [Footnote: From the Obituary Notices of the _Proceedings of the Royal Society_, vol. 44.] [1888] Charles Robert Darwin was the fifth child and second son of Robert Waring Darwin and Susannah Wedgwood, and was born on the 12th February, 1809, at Shrewsbury, where his father was a physician in large practice. Mrs. Robert Darwin died when her son Charles was only eight years old, and he hardly remembered her. A daughter of the famous Josiah Wedgwood, who created a new branch of the potter's art, and established the great works of Etruria, could hardly fail to transmit important mental and moral qualities to her children; and there is a solitary record of her direct influence in the story told by a schoolfellow, who remembers Charles Darwin "bringing a flower to school, and saying that his mother had taught him how, by looking at the inside of the blossom, the name of the plant could be discovered." (I., p. 28. [Footnote: The references throughout this notice are to the _Life and Letters_, unless the contrary is expressly stated.]) The theory that men of genius derive their qualities from their mothers, however, can hardly derive support from Charles Darwin's case, in the face of the patent influence of his paternal forefathers. Dr. Darwin, indeed, though a man of marked individuality of character, a quick and acute observer, with much practical sagacity, is said not to have had a scientific mind. But when his son adds that his father "formed a theory for almost everything that occurred" (I., p. 20), he indicates a highly probable source for that inability to refrain from forming an hypothesis on every subject which he confesses to be one of the leading characteristics of his own mind, some pages further on (I., p. 103). Dr. R. W. Darwin, again, was the third son of Erasmus Darwin, also a physician of great repute, who shared the intimacy of Watt and Priestley, and was widely known as the author of "Zoonomia," and other voluminous poetical and prose works which had a great vogue in the latter half of the eighteenth century. The celebrity which they enjoyed was in part due to the attractive style (at least according to the taste of that day) in which the author's extensive, though not very profound, acquaintance with natural phenomena was set forth; but in a still greater degree, probably, to the boldness of the speculative views, always ingenious and sometimes fantastic, in which he indulged. The conception of evolution set afoot by De Maillet and others, in the early part of the century, not only found a vigorous champion in Erasmus Darwin, but he propounded an hypothesis as to the manner in which the species of animals and plants have acquired their characters, which is identical in principle with that subsequently rendered famous by Lamarck. That Charles Darwin's chief intellectual inheritance came to him from the paternal side, then, is hardly doubtful. But there is nothing to show that he was, to any sensible extent, directly influenced by his grandfather's biological work. He tells us that a perusal of the "Zoonomia" in early life produced no effect upon him, although he greatly admired it; and that, on reading it again, ten or fifteen years afterwards, he was much disappointed, "the proportion of speculation being so large to the facts given." But with his usual anxious candour he adds, "Nevertheless, it is probable that the hearing, rather early in life, such views maintained and praised, may have favoured my upholding them, in a different form, in my 'Origin of Species.'" (I., p. 38.) Erasmus Darwin was in fact an anticipator of Lamarck, and not of Charles Darwin; there is no trace in his works of the conceptions by the addition of which his grandson metamorphosed the theory of evolution as applied to living things and gave it a new foundation. Charles Darwin's childhood and youth afforded no intimation that he would he, or do, anything out of the common run. In fact, the prognostications of the educational authorities into whose hands he first fell were most distinctly unfavourable; and they counted the only boy of original genius who is known to have come under their hands as no better than a dunce. The history of the educational experiments to which Darwin was subjected is curious, and not without a moral for the present generation. There were four of them, and three were failures. Yet it cannot be said that the materials on which the pedagogic powers operated were other than good. In his boyhood Darwin was strong, well-grown, and active, taking the keen delight in field sports and in every description of hard physical exercise which is natural to an English country-bred lad; and, in respect of things of the mind, he was neither apathetic, nor idle, nor one-sided. The "Autobiography" tells us that he "had much zeal for whatever interested" him, and he was interested in many and very diverse topics. He could work hard, and liked a complex subject better than an easy one. The "clear geometrical proofs" of Euclid delighted him. His interest in practical chemistry, carried out in an extemporised laboratory, in which he was permitted to assist by his elder brother, kept him late at work, and earned him the nickname of "gas" among his schoolfellows. And there could have been no insensibility to literature in one who, as a boy, could sit for hours reading Shakespeare, Milton, Scott, and Byron; who greatly admired some of the Odes of Horace; and who, in later years, on board the "Beagle," when only one book could be carried on an expedition, chose a volume of Milton for his companion. Industry, intellectual interests, the capacity for taking pleasure in deductive reasoning, in observation, in experiment, no less than in the highest works of imagination: where these qualities are present any rational system of education should surely be able to make something of them. Unfortunately for Darwin, the Shrewsbury Grammar School, though good of its kind, was an institution of a type universally prevalent in this country half a century ago, and by no means extinct at the present day. The education given was "strictly classical," "especial attention" being "paid to verse-making," while all other subjects, except a little ancient geography and history, were ignored. Whether, as in some famous English schools at that date and much later, elementary arithmetic was also left out of sight does not appear; but the instruction in Euclid which gave Charles Darwin so much satisfaction was certainly supplied by a private tutor. That a boy, even in his leisure hours, should permit himself to be interested in any but book-learning seems to have been regarded as little better than an outrage by the head master, who thought it his duty to administer a public rebuke to young Darwin for wasting his time on such a contemptible subject as chemistry. English composition and literature, modern languages, modern history, modern geography, appear to have been considered to be as despicable as chemistry. For seven long years Darwin got through his appointed tasks; construed without cribs, learned by rote whatever was demanded, and concocted his verses in approved schoolboy fashion. And the result, as it appeared to his mature judgment, was simply negative. "The school as a means of education to me was simply a blank." (I. p. 32.) On the other hand, the extraneous chemical exercises, which the head master treated so contumeliously, are gratefully spoken of as the "best part" of his education while at school. Such is the judgment of the scholar on the school; as might be expected, it has its counterpart in the judgment of the school on the scholar. The collective intelligence of the staff of Shrewsbury School could find nothing but dull mediocrity in Charles Darwin. The mind that found satisfaction in knowledge, but very little in mere learning; that could appreciate literature, but had no particular aptitude for grammatical exercises; appeared to the "strictly classical" pedagogue to be no mind at all. As a matter of fact, Darwin's school education left him ignorant of almost all the things which it would have been well for him to know, and untrained in all the things it would have been useful for him to be able to do, in after life. Drawing, practice in English composition, and instruction in the elements of the physical sciences, would not only have been infinitely valuable to him in reference to his future career, but would have furnished the discipline suited to his faculties, whatever that career might be. And a knowledge of French and German, especially the latter, would have removed from his path obstacles which he never fully overcame. Thus, starved and stunted on the intellectual side, it is not surprising that Charles Darwin's energies were directed towards athletic amusements and sport, to such an extent, that even his kind and sagacious father could be exasperated into telling him that "he cared for nothing but shooting, dogs, and rat-catching." (I. p. 32.) It would be unfair to expect even the wisest of fathers to have foreseen that the shooting and the rat-catching, as training in the ways of quick observation and in physical endurance, would prove more valuable than the construing and verse-making to his son, whose attempt, at a later period of his Life, to persuade himself "that shooting was almost an intellectual employment: it required so much skill to judge where to find most game, and to hunt the dogs well" (I. p. 43), was by no means so sophistical as he seems to have been ready to admit. In 1825, Dr. Darwin came to the very just conclusion that his son Charles would do no good by remaining at Shrewsbury School, and sent him to join his elder brother Erasmus, who was studying medicine at Edinburgh, with the intention that the younger son should also become a medical practitioner. Both sons, however, were well aware that their inheritance would relieve them from the urgency of the struggle for existence which most professional men have to face; and they seemed to have allowed their tastes, rather than the medical curriculum, to have guided their studies. Erasmus Darwin was debarred by constant ill-health from seeking the public distinction which his high intelligence and extensive knowledge would, under ordinary circumstances, have insured. He took no great interest in biological subjects, but his companionship must have had its influence on his brother. Still more was exerted by friends like Coldstream and Grant, both subsequently well-known zoologists (and the latter an enthusiastic Lamarckian), by whom Darwin was induced to interest himself in marine zoology. A notice of the ciliated germs of _Flustra_, communicated to the Plinian Society in 1826, was the first fruits of Darwin's half century of scientific work. Occasional attendance at the Wernerian Society brought him into relation with that excellent ornithologist the elder Macgillivray, and enabled him to see and hear Audubon. Moreover, he got lessons in bird-stuffing from a negro, who had accompanied the eccentric traveller Waterton in his wanderings, before settling in Edinburgh. No doubt Darwin picked up a great deal of valuable knowledge during his two years' residence in Scotland; but it is equally clear that next to none of it came through the regular channels of academic education. Indeed, the influence of the Edinburgh professoriate appears to have been mainly negative, and in some cases deterrent; creating in his mind, not only a very low estimate of the value of lectures, but an antipathy to the subjects which had been the occasion of the boredom inflicted upon him by their instrumentality. With the exception of Hope, the Professor of Chemistry, Darwin found them all "intolerably dull." Forty years afterwards he writes of the lectures of the Professor of Materia Medica that they were "fearful to remember." The Professor of Anatomy made his lectures "as dull as he was himself," and he must have been very dull to have wrung from his victim the sharpest personal remark recorded as his. But the climax seems to have been attained by the Professor of Geology and Zoology, whose prælections were so "incredibly dull" that they produced in their hearer the somewhat rash determination never "to read a book on geology or in any way to study the science" so long as he lived. (I. p. 41.) There is much reason to believe that the lectures in question were eminently qualified to produce the impression which they made; and there can be little doubt, that Darwin's conclusion that his time was better employed in reading than in listening to such lectures was a sound one. But it was particularly unfortunate that the personal and professorial dulness of the Professor of Anatomy, combined with Darwin's sensitiveness to the disagreeable concomitants of anatomical work, drove him away from the dissecting room. In after life, he justly recognised that this was an "irremediable evil" in reference to the pursuits he eventually adopted; indeed, it is marvellous that he succeeded in making up for his lack of anatomical discipline, so far as his work on the Cirripedes shows he did. And the neglect of anatomy had the further unfortunate result that it excluded him from the best opportunity of bringing himself into direct contact with the facts of nature which the University had to offer. In those days, almost the only practical scientific work accessible to students was anatomical, and the only laboratory at their disposal the dissecting room. We may now console ourselves with the reflection that the partial evil was the general good. Darwin had already shown an aptitude for practical medicine (I. p. 37); and his subsequent career proved that he had the making of an excellent anatomist. Thus, though his horror of operations would probably have shut him off from surgery, there was nothing to prevent him (any more than the same peculiarity prevented his father) from passing successfully through the medical curriculum and becoming, like his father and grandfather, a successful physician, in which case "The Origin of Species" would not have been written. Darwin has jestingly alluded to the fact that the shape of his nose (to which Captain Fitzroy objected), nearly prevented his embarkation in the "Beagle"; it may be that the sensitiveness of that organ secured him for science. At the end of two years' residence in Edinburgh it hardly needed Dr. Darwin's sagacity to conclude that a young man, who found nothing but dulness in professorial lucubrations, could not bring himself to endure a dissecting room, fled from operations, and did not need a profession as a means of livelihood, was hardly likely to distinguish himself as a student of medicine. He therefore made a new suggestion, proposing that his son should enter an English University and qualify for the ministry of the Church. Charles Darwin found the proposal agreeable, none the less, probably, that a good deal of natural history and a little shooting were by no means held, at that time, to be incompatible with the conscientious performance of the duties of a country clergyman. But it is characteristic of the man, that he asked time for consideration, in order that he might satisfy himself that he could sign the Thirty-nine Articles with a clear conscience. However, the study of "Pearson on the Creeds" and a few other books of divinity soon assured him that his religious opinions left nothing to be desired on the score of orthodoxy, and he acceded to his father's proposition. The English University selected was Cambridge; but an unexpected obstacle arose from the fact that, within the two years which had elapsed, since the young man who had enjoyed seven years of the benefit of a strictly classical education had left school, he had forgotten almost everything he had learned there, "even to some few of the Greek letters." (I. p. 46.) Three months with a tutor, however, brought him back to the point of translating Homer and the Greek Testament "with moderate facility," and Charles Darwin commenced the third educational experiment of which he was the subject, and was entered on the books of Christ's College in October 1827. So far as the direct results of the academic training thus received are concerned, the English University was not more successful than the Scottish. "During the three years which I spent at Cambridge my time was wasted, as far as the academical studies were concerned, as completely as at Edinburgh and as at school." (I. p. 46.) And yet, as before, there is ample evidence that this negative result cannot be put down to any native defect on the part of the scholar. Idle and dull young men, or even young men who being neither idle nor dull, are incapable of caring for anything but some hobby, do not devote themselves to the thorough study of Paley's "Moral Philosophy," and "Evidences of Christianity"; nor are their reminiscences of this particular portion of their studies expressed in terms such as the following: "The logic of this book [the 'Evidences'] and, as I may add, of his 'Natural Theology' gave me as much delight as did Euclid." (I. p. 47.) The collector's instinct, strong in Darwin from his childhood, as is usually the case in great naturalists, turned itself in the direction of Insects during his residence at Cambridge. In childhood it had been damped by the moral scruples of a sister, as to the propriety of catching and killing insects for the mere sake of possessing them, but now it broke out afresh, and Darwin became an enthusiastic beetle collector. Oddly enough he took no scientific interest in beetles, not even troubling himself to make out their names; his delight lay in the capture of a species which turned out to be rare or new, and still more in finding his name, as captor, recorded in print. Evidently, this beetle-hunting hobby had little to do with science, but was mainly a new phase of the old and undiminished love of sport. In the intervals of beetle-catching, when shooting and hunting were not to be had, riding across country answered the purpose. These tastes naturally threw the young undergraduate among a set of men who preferred hard riding: to hard reading, and wasted the midnight oil upon other pursuits than that of academic distinction. A superficial observer might have had some grounds to fear that Dr. Darwin's wrathful prognosis might yet be verified. But if the eminently social tendencies of a vigorous and genial nature sought an outlet among a set of jovial sporting friends, there were other and no less strong proclivities which brought him into relation with associates of a very different stamp. Though almost without ear and with a very defective memory for music, Darwin was so strongly and pleasurably affected by it that he became a member of a musical society; and an equal lack of natural capacity for drawing did not prevent him from studying good works of art with much care. An acquaintance with even the rudiments of physical science was no part of the requirements for the ordinary Cambridge degree. But there were professors both of Geology and of Botany whose lectures were accessible to those who chose to attend them. The occupants of these chairs, in Darwin's time, were eminent men and also admirable lecturers in their widely different styles. The horror of geological lectures which Darwin had acquired at Edinburgh, unfortunately prevented him from going within reach of the fervid eloquence of Sedgwick; but he attended the botanical course, and though he paid no serious attention to the subject, he took great delight in the country excursions, which Henslow so well knew how to make both pleasant and instructive. The Botanical Professor was, in fact, a man of rare character and singularly extensive acquirements in all branches of natural history. It was his greatest pleasure to place his stores of knowledge at the disposal of the young men who gathered about him, and who found in him, not merely an encyclopedic teacher but a wise counsellor, and, in case of worthiness, a warm friend. Darwin's acquaintance with him soon ripened into a friendship which was terminated only by Henslow's death in 1861, when his quondam pupil gave touching expression to his sense of what he owed to one whom he calls (in one of his letters) his "dear old master in Natural History." (II. p. 217.) It was by Henslow's advice that Darwin was led to break the vow he had registered against making an acquaintance with geology; and it was through Henslow's good offices with Sedgwick that he obtained the opportunity of accompanying the Geological Professor on one of his excursions in Wales. He then received a certain amount of practical instruction in Geology, the value of which he subsequently warmly acknowledged. (I. p. 237.) In another direction, Henslow did him an immense, though not altogether intentional service, by recommending him to buy and study the recently published first volume of Lyell's "Principles." As an orthodox geologist of the then dominant catastrophic school, Henslow accompanied his recommendation with the admonition on no account to adopt Lyell's general views. But the warning fell on deaf ears, and it is hardly too much to say that Darwin's greatest work is the outcome of the unflinching application to Biology of the leading idea and the method applied in the "Principles" to geology. [Footnote: "After my return to England it appeared to me that by following the example of Lyell in Geology, and by collecting all facts which bore in any way on the variation of animals and plants under domestication and nature, some light might perhaps be thrown on the whole subject [of the origin of species]." (I. p. 83.) See also the dedication of the second edition of the _Journal of a Naturalist_]. Finally, it was through Henslow, and at his suggestion, that Darwin was offered the appointment to the "Beagle" as naturalist. During the latter part of Darwin's residence at Cambridge the prospect of entering the Church, though the plan was never formally renounced, seems to have grown very shadowy. Humboldt's "Personal Narrative," and Herschel's "Introduction to the Study of Natural Philosophy," fell in his way and revealed to him his real vocation. The impression made by the former work was very strong. "My whole course of life," says Darwin in sending a message to Humboldt, "is due to having read and re-read, as a youth, his personal narrative." (I. p. 336.) The description of Teneriffe inspired Darwin with such a strong desire to visit the island, that he took some steps towards going there--inquiring about ships, and so on. But, while this project was fermenting, Henslow, who had been asked to recommend a naturalist for Captain Fitzroy's projected expedition, at once thought of his pupil. In his letter of the 24th August, 1831, he says: "I have stated that I consider you to be the best qualified person I know of who is likely to undertake such a situation. I state this--not on the supposition of your being a _finished_ naturalist, but as amply qualified for collecting, observing, and noting anything worthy to be noted in Natural History.... The voyage is to last two years, and if you take plenty of books with you, anything you please may be done." (I. p. 193.) The state of the case could not have been better put. Assuredly the young naturalist's theoretical and practical scientific training had gone no further than might suffice for the outfit of an intelligent collector and note-taker. He was fully conscious of the fact, and his ambition hardly rose above the hope that he should bring back materials for the scientific "lions" at home of sufficient excellence to prevent them from turning and rending him. (I. p. 248.) But a fourth educational experiment was to be tried. This time Nature took him in hand herself and showed him the way by which, to borrow Henslow's prophetic phrase, "anything he pleased might be done." The conditions of life presented by a ship-of-war of only 242 tons burthen, would not, _primâ facie_, appear to be so favourable to intellectual development as those offered by the cloistered retirement of Christ's College. Darwin had not even a cabin to himself; while, in addition to the hindrances and interruptions incidental to sea-life, which can be appreciated only by those who have had experience of them, sea-sickness came on whenever the little ship was "lively"; and, considering the circumstances of the cruise, that must have been her normal state. Nevertheless, Darwin found on board the "Beagle" that which neither the pedagogues of Shrewsbury, nor the professoriate of Edinburgh, nor the tutors of Cambridge had managed to give him. "I have always felt that I owe to the voyage the first real training or education of my mind (I. p. 61);" and in a letter written as he was leaving England, he calls the voyage on which he was starting, with just insight, his "second life." (I. p. 214.) Happily for Darwin's education, the school time of the "Beagle" lasted five years instead of two; and the countries which the ship visited were singularly well fitted to provide him with object-lessons, on the nature of things, of the greatest value. While at sea, he diligently collected, studied, and made copious notes upon the surface Fauna. But with no previous training in dissection, hardly any power of drawing, and next to no knowledge of comparative anatomy, his occupation with work of this kind--notwithstanding all his zeal and industry--resulted, for the most part, in a vast accumulation of useless manuscript. Some acquaintance with the marine _Crustacea_, observations on _Planariæ_ and on the ubiquitous _Sagitta_, seem to have been the chief results of a great amount of labour in this direction. It was otherwise with the terrestrial phenomena which came under the voyager's notice: and Geology very soon took her revenge for the scorn which the much-bored Edinburgh student had poured upon her. Three weeks after leaving England the ship touched land for the first time at St. Jago, in the Cape de Verd Islands, and Darwin found his attention vividly engaged by the volcanic phenomena and the signs of upheaval which the island presented. His geological studies had already indicated the direction in which a great deal might be done, beyond collecting; and it was while sitting beneath a low lava cliff on the shore of this island, that a sense of his real capability first dawned upon Darwin, and prompted the ambition to write a book on the geology of the various countries visited. (I. p. 66.) Even at this early date, Darwin must have thought much on geological topics, for he was already convinced of the superiority of Lyell's views to those entertained by the catastrophists [Footnote: "I had brought with me the first volume of Lyell's _Principles of Geology_, which I studied attentively; and the book was of the highest service to me in many ways. The very first place which I examined, namely, St. Jago, in the Cape de Verd Islands, showed me clearly the wonderful superiority of Lyell's manner of treating Geology, compared with that of any other author whose works I had with me or ever afterwards read "-(I. p. 62.)]; and his subsequent study of the tertiary deposits and of the terraced gravel beds of South America was eminently fitted to strengthen that conviction. The letters from South America contain little reference to any scientific topic except geology; and even the theory of the formation of coral reefs was prompted by the evidence of extensive and gradual changes of level afforded by the geology of South America; "No other work of mine," he says, "was begun in so deductive a spirit as this; for the whole theory was thought out on the West Coast of South America, before I had seen a true coral reef. I had, therefore, only to verify and extend my views by a careful examination of living reefs." (I. p. 70.) In 1835, when starting from Lima for the Galapagos, he recommends his friend, W. D. Fox, to take up geology:--"There is so much larger a field for thought than in the other branches of Natural History. I am become a zealous disciple of Mr. Lyell's views, as made known in his admirable book. Geologising in South America, I am tempted to carry parts to a greater extent even than he does. Geology is a capital science to begin with, as it requires nothing but a little reading, thinking, and hammering." (I. p. 263.) The truth of the last statement, when it was written, is a curious mark of the subsequent progress of geology. Even so late as 1836, Darwin speaks of being "much more inclined for geology than the other branches of Natural History." (I. p. 275.) At the end of the letter to Mr. Fox, however, a little doubt is expressed whether zoological studies might not, after all, have been more profitable; and an interesting passage in the "Autobiography" enables us to understand the origin of this hesitation. "During the voyage of the 'Beagle' I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos; secondly, by the manner in which closely-allied animals replace one another in proceeding southwards over the continent; and, thirdly, by the South American character of most of the productions of the Galapagos Archipelago, and, more especially, by the manner in which they differ slightly on each island of the group; some of the islands appearing to be very ancient in a geological sense. "It was evident that such facts as these, as well as many others, could only be explained on the supposition that species gradually become modified; and the subject haunted me. But it was equally evident that neither the action of the surrounding conditions, nor the will of the organisms (especially in the case of plants) could account for the innumerable cases in which organisms of every kind are beautifully adapted to their habits of life; for instance, a woodpecker or a tree-frog to climb trees, or a seed for dispersal by hooks or plumes. I had always been much struck by such adaptations, and until these could be explained it seemed to me almost useless to endeavour to prove by indirect evidence that species have been modified." (I. p. 82.) The facts to which reference is here made were, without doubt, eminently fitted to attract the attention of a philosophical thinker; but, until the relations of the existing with the extinct species and of the species of the different geographical areas with one another, were determined with some exactness, they afforded but an unsafe foundation for speculation. It was not possible that this determination should have been effected before the return of the "Beagle" to England; and thus the date which Darwin (writing in 1837) assigns to the dawn of the new light which was rising in his mind becomes intelligible. [Footnote: I am indebted to Mr. F. Darwin for the knowledge of a letter addressed by his father to Dr. Otto Zacharias in 1877 which contains the following paragraph, confirmatory of the view expressed above: "When I was on board the _Beagle_, I believed in the permanence of species, but, as far as I can remember, vague doubts occasionally flitted across my mind. On my return home in the autumn of 1836, I immediately began to prepare my journal for publication, and then saw how many facts indicated the common descent of species, so that in July, 1837, I opened a note-book to record any facts which might bear on the question. But I did not become convinced that species were mutable until, I think, two or three years had elapsed."] "In July opened first note-book on Transmutation of Species. Had been greatly struck from about the month of previous March on character of South American fossils and species on Galapagos Archipelago. These facts (especially latter) origin of all my views." (I. p. 276.) From March, 1837, then, Darwin, not without many misgivings and fluctuations of opinion, inclined towards transmutation as a provisional hypothesis. Three months afterwards he is hard at work collecting facts for the purpose of testing the hypothesis; and an almost apologetic passage in a letter to Lyell shows that, already, the attractions of biology are beginning to predominate over those of geology. "I have lately been sadly tempted to be idle--[Footnote: Darwin generally uses the word "idle" in a peculiar sense. He means by it working hard at something he likes when he ought to be occupied with a less attractive subject. Though it sounds paradoxical, there is a good deal to be said in favour of this view of pleasant work.]that is, as far as pure Geology is concerned--by the delightful number of new views which have been coming in thickly and steadily--on the classification and affinities and instincts of animals--bearing on the question of species. Note-book after note-book has been filled with facts which begin to group themselves _clearly_ under sub-laws." (I. p. 298.) The problem which was to be Darwin's chief subject of occupation for the rest of his life thus presented itself, at first, mainly under its distributional aspect. Why do species present certain relations in space and in time? Why are the animals and plants of the Galapagos Archipelago so like those of South America and yet different from them? Why are those of the several islets more or less different from one another? Why are the animals of the latest geological epoch in South America similar in _facies_ to those which exist in the same region at the present day, and yet specifically or generically different? The reply to these questions, which was almost universally received fifty years ago, was that animals and plants were created such as they are; and that their present distribution, at any rate so far as terrestrial organisms are concerned, has been effected by the migration of their ancestors from the region in which the ark stranded after the subsidence of the deluge. It is true that the geologists had drawn attention to a good many tolerably serious difficulties in the way of the diluvial part of this hypothesis, no less than to the supposition that the work of creation had occupied only a brief space of time. But even those, such as Lyell, who most strenuously argued in favour of the sufficiency of natural causes for the production of the phenomena of the inorganic world, held stoutly by the hypothesis of creation in the case of those of the world of life. For persons who were unable to feel satisfied with the fashionable doctrine, there remained only two alternatives--the hypothesis of spontaneous generation, and that of descent with modification. The former was simply the creative hypothesis with the creator left out; the latter had already been propounded by De Maillet and Erasmus Darwin, among others; and, later, systematically expounded by Lamarck. But in the eyes of the naturalist of the "Beagle" (and, probably, in those of most sober thinkers), the advocates of transmutation had done the doctrine they expounded more harm than good. Darwin's opinion of the scientific value of the "Zoonomia" has already been mentioned. His verdict on Lamarck is given in the following passage of a letter to Lyell (March, 1863):-- "Lastly, you refer repeatedly to my view as a modification of Lamarck's doctrine of development and progression. If this is your deliberate opinion there is nothing to be said, but it does not seem so to me. Plato, Buffon, my grandfather, before Lamarck and others, propounded the _obvious_ view that if species were not created separately they must have descended from other species, and I can see nothing else in common between the "Origin" and Lamarck. I believe this way of putting the case is very injurious to its acceptance, as it implies necessary progression, and closely connects Wallace's and my views with what I consider, after two deliberate readings, as a wretched book, and one from which (I well remember to my surprise) I gained nothing." "But," adds Darwin with a little touch of banter, "I know you rank it higher, which is curious, as it did not in the least shake your belief." (III. p. 14; see also p. 16, "to me it was an absolutely useless book.") Unable to find any satisfactory theory of the process of descent with modification in the works of his predecessors, Darwin proceeded to lay the foundations of his own views independently; and he naturally turned, in the first place, to the only certainly known examples of descent with modification, namely, those which are presented by domestic animals and cultivated plants. He devoted himself to the study of these cases with a thoroughness to which none of his predecessors even remotely approximated; and he very soon had his reward in the discovery "that selection was the keystone of man's success in making useful races of animals and plants." (I. p. 83.) This was the first step in Darwin's progress, though its immediate result was to bring him face to face with a great difficulty. "But how selection could be applied to organisms living in a state of nature remained for some time a mystery to me." (I. p. 83.) The key to this mystery was furnished by the accidental perusal of the famous essay of Malthus "On Population" in the autumn of 1838. The necessary result of unrestricted multiplication is competition for the means of existence. The success of one competitor involves the failure of the rest, that is, their extinction; and this "selection" is dependent on the better adaptation of the successful competitor to the conditions of the competition. Variation occurs under natural, no less than under artificial, conditions. Unrestricted multiplication implies the competition of varieties and the selection of those which are relatively best adapted to the conditions. Neither Erasmus Darwin, nor Lamarck, had any inkling of the possibility of this process of "natural selection"; and though it had been foreshadowed by Wells in 1813, and more fully stated by Matthew in 1831, the speculations of the latter writer remained unknown to naturalists until after the publication of the "Origin of Species." Darwin found in the doctrine of the selection of favourable variations by natural causes, which thus presented itself to his mind, not merely a probable theory of the origin of the diverse species of living forms, but that explanation of the phenomena of adaptation, which previous speculations had utterly failed to give. The process of natural selection is, in fact, dependent on adaptation--it is all one, whether one says that the competitor which survives is the "fittest" or the "best adapted." And it was a perfectly fair deduction that even the most complicated adaptations might result from the summation of a long series of simple favourable variations. Darwin notes as a serious defect in the first sketch of his theory that he had omitted to consider one very important problem, the solution of which did not occur to him till some time afterwards. "This problem is the tendency in organic beings descended from the same stock to diverge in character as they become modified.... The solution, as I believe, is that the modified offspring of all dominant and increasing forms tend to become adapted to many and highly diversified places in the economy of nature." (I. p. 84.) It is curious that so much importance should be attached to this supplementary idea. It seems obvious that the theory of the origin of species by natural selection necessarily involves the divergence of the forms selected. An individual which varies, _ipso facto_ diverges from the type of its species; and its progeny, in which the variation becomes intensified by selection, must diverge still more, not only from the parent stock, but from any other race of that stock starting from, a variation of a different character. The selective process could not take place unless the selected variety was either better adapted to the conditions than the original stock, or adapted to other conditions than the original stock. In the first case, the original stock would be sooner or later extirpated; in the second, the type, as represented by the original stock and the variety, would occupy more diversified stations than it did before. The theory, essentially such as it was published fourteen years later, was written out in 1844, and Darwin was so fully convinced of the importance of his work, as it then stood, that he made special arrangements for its publication in case of his death. But it is a singular example of reticent fortitude, that, although for the next fourteen years the subject never left his mind, and during the latter half of that period he was constantly engaged in amassing facts bearing upon it from wide reading, a colossal correspondence, and a long series of experiments, only two or three friends were cognisant of his views. To the outside world he seemed to have his hands quite sufficiently full of other matters. In 1844, he published his observations on the volcanic islands visited during the voyage of the "Beagle." In 1845, a largely remodelled edition of his "Journal" made its appearance, and immediately won, as it has ever since held, the favour of both the scientific and the unscientific public. In 1846, the "Geological Observations in South America" came out, and this book was no sooner finished than Darwin set to work upon the Cirripedes. He was led to undertake this long and heavy task, partly by his desire to make out the relations of a very anomalous form which he had discovered on the coast of Chili; and partly by a sense of "presumption in accumulating facts and speculating on the subject of variation without having worked out my due share of species." (II. p. 31.) The eight or nine years of labour, which resulted in a monograph of first-rate importance in systematic zoology (to say nothing of such novel points as the discovery of complemental males), left Darwin no room to reproach himself on this score, and few will share his "doubt whether the work was worth the consumption of so much time." (I. p. 82.) In science no man can safely speculate about the nature and relation of things with which he is unacquainted at first hand, and the acquirement of an intimate and practical knowledge of the process of species-making and of all the uncertainties which underlie the boundaries between species and varieties, drawn by even the most careful and conscientious systematists [Footnote: "After describing a set of forms as distinct species, tearing up my MS., and making them one species, tearing that up and making them separate, and then making them one again (which has happened to me), I have gnashed my teeth, cursed species, and asked what sin I had committed to be so punished." (II. p. 40.) Is there any naturalist provided with a logical sense and a large suite of specimens, who has not undergone pangs of the sort described in this vigorous paragraph, which might, with advantage, be printed on the title-page of every systematic monograph as a warning to the uninitiated?] were of no less importance to the author of the "Origin of Species" than was the bearing of the Cirripede work upon "the principles of a natural classification." (I. p. 81.) No one, as Darwin justly observes, has a "right to examine the question of species who has not minutely described many." (II. p. 39.) In September, 1854, the Cirripede work was finished, "ten thousand barnacles" had been sent "out of the house, all over the world," and Darwin had the satisfaction of being free to turn again to his "old notes on species." In 1855, he began to breed pigeons, and to make observations on the effects of use and disuse, experiments on seeds, and so on, while resuming his industrious collection of facts, with a view "to see how far they favour or are opposed to the notion that wild species are mutable or immutable. I mean with my utmost power to give all arguments and facts on both sides. I have a _number_ of people helping me every way, and giving me most valuable assistance; but I often doubt whether the subject will not quite overpower me." (II. p. 49.) Early in 1856, on Lyell's advice, Darwin began to write out his views on the origin of species on a scale three or four times as extensive as that of the work published in 1859. In July of the same year he gave a brief sketch of his theory in a letter to Asa Gray; and, in the year 1857, his letters to his correspondents show him to be busily engaged on what he calls his "big book." (II. pp. 85, 94.) In May, 1857, Darwin writes to Wallace: "I am now preparing my work [on the question how and in what way do species and varieties differ from each other] for publication, but I find the subject so very large, that, though I have written many chapters, I do not suppose I shall go to press for two years." (II. p. 95.) In December, 1857, he writes, in the course of a long letter to the same correspondent, "I am extremely glad to hear that you are attending to distribution in accordance with theoretical ideas. I am a firm believer that without speculation there is no good and original observation." (II. p. 108.) [Footnote: The last remark contains a pregnant truth, but it must be confessed it hardly squares with the declaration in the _Autobiography_, (I. p. 83), that he worked on "true Baconian principles."] In June, 1858, he received from Mr. Wallace, then in the Malay Archipelago, an "Essay on the tendency of varieties to depart indefinitely from the original type," of which Darwin says, "If Wallace had my MS. sketch written out in 1842 he could not have made a better short abstract! Even his terms stand now as heads of my chapters. Please return me the MS., which he does not say he wishes me to publish, but I shall, of course, at once write and offer to send it to any journal. So all my originality, whatever it may amount to, will be smashed, though my book, if ever it will have any value, will not be deteriorated; as all the labour consists in the application of the theory." (II. p. 116.) Thus, Darwin's first impulse was to publish Wallace's essay without note or comment of his own. But, on consultation with Lyell and Hooker, the latter of whom had read the sketch of 1844, they suggested, as an undoubtedly more equitable course, that extracts from the MS. of 1844 and from the letter to Dr. Asa Gray should be communicated to the Linnean Society along with Wallace's essay. The joint communication was read on July 1, 1858, and published under the title "On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection." This was followed, on Darwin's part, by the composition of a summary account of the conclusions to which his twenty years' work on the species question had led him. It occupied him for thirteen months, and appeared in November, 1859, under the title "On the Origin of Species by means of Natural Selection or the Preservation of Favoured Races in the Struggle of Life." It is doubtful if any single book, except the "Principia," ever worked so great and so rapid a revolution in science, or made so deep an impression on the general mind. It aroused a tempest of opposition and met with equally vehement support, and it must be added that no book has been more widely and persistently misunderstood by both friends and foes. In 1861, Darwin remarks to a correspondent, "You understand my book perfectly, and that I find a very rare event with my critics." (I. p. 313.) The immense popularity which the "Origin" at once acquired was no doubt largely due to its many points of contact with philosophical and theological questions in which every intelligent man feels a profound interest; but a good deal must be assigned to a somewhat delusive simplicity of style, which tends to disguise the complexity and difficulty of the subject, and much to the wealth of information on all sorts of curious problems of natural history, which is made accessible to the most unlearned reader. But long occupation with the work has led the present writer to believe that the "Origin of Species" is one of the hardest of books to master; [Footnote: He is comforted to find that probably the best qualified judge among all the readers of the _Origin_ in 1859 was of the same opinion. Sir J. Hooker writes, "It is the very hardest book to read, to full profit, that I ever tried." (II. p. 242.)] and he is justified in this conviction by observing that although the "Origin" has been close on thirty years before the world, the strangest misconceptions of the essential nature of the theory therein advocated are still put forth by serious writers. Although, then, the present occasion is not suitable for any detailed criticism of the theory, or of the objections which have been brought against it, it may not be out of place to endeavour to separate the substance of the theory from its accidents; and to show that a variety not only of hostile comments, but of friendly would-be improvements lose their _raison d'être_ to the careful student. Observation proves the existence among all living beings of phenomena of three kinds, denoted by the terms heredity, variation, and multiplication. Progeny tend to resemble their parents; nevertheless all their organs and functions are susceptible of departing more or less from the average parental character; and their number is in excess of that of their parents. Severe competition for the means of living, or the struggle for existence, is a necessary consequence of unlimited multiplication; while selection, or the preservation of favourable variations and the extinction of others, is a necessary consequence of severe competition. "Favourable variations" are those which are better adapted to surrounding conditions. It follows, therefore, that every variety which is selected into a species is so favoured and preserved in consequence of being, in some one or more respects, better adapted to its surroundings than its rivals. In other words, every species which exists, exists in virtue of adaptation, and whatever accounts for that adaptation accounts for the existence of the species. To say that Darwin has put forward a theory of the adaptation of species, but not of their origin, is therefore to misunderstand the first principles of the theory. For, as has been pointed out, it is a necessary consequence of the theory of selection that every species must have some one or more structural or functional peculiarities, in virtue of the advantage conferred by which, it has fought through the crowd of its competitors and achieved a certain duration. In this sense, it is true that every species has been "originated" by selection. There is another sense, however, in which it is equally true that selection originates nothing. "Unless profitable variations ... occur natural selection can do nothing" ("Origin," Ed. I. p. 82). "Nothing can be effected unless favourable variations occur" (_ibid_., p. 108). "What applies to one animal will apply throughout time to all animals--that is, if they vary--for otherwise natural selection can do nothing. So it will be with plants" (_ibid_., p. 113). Strictly speaking, therefore, the origin of species in general lies in variation; while the origin of any particular species lies, firstly, in the occurrence, and secondly, in the selection and preservation of a particular variation. Clearness on this head will relieve one from the necessity of attending to the fallacious assertion that natural selection is a _deus ex machinâ_, or occult agency. Those, again, who confuse the operation of the natural causes which bring about variation and selection with what they are pleased to call "chance" can hardly have read the opening paragraph of the fifth chapter of the "Origin" (Ed. I, p. 131): "I have sometimes spoken as if the variations ... had been due to chance. This is of course a wholly incorrect expression, but it seems to acknowledge plainly our ignorance of the cause of each particular variation." Another point of great importance to the right comprehension of the theory, is, that while every species must needs have some adaptive advantageous characters to which it owes its preservation by selection, it may possess any number of others which are neither advantageous nor disadvantageous, but indifferent, or even slightly disadvantageous. (_Ibid_., p. 81.) For variations take place, not merely in one organ or function at a time, but in many; and thus an advantageous variation, which gives rise to the selection of a new race or species, may be accompanied by others which are indifferent, but which are just as strongly hereditary as the advantageous variations. The advantageous structure is but one product of a modified general constitution which may manifest itself by several other products; and the selective process carries the general constitution along with the advantageous special peculiarity. A given species of plant may owe its existence to the selective adaptation of its flowers to insect fertilisers; but the character of its leaves may be the result of variations of an indifferent character. It is the origin of variations of this kind to which Darwin refers in his frequent reference to what he calls "laws of correlation of growth" or "correlated variation." These considerations lead us further to see the inappropriateness of the objections raised to Darwin's theory on the ground that natural selection does not account for the first commencements of useful organs. But it does not pretend to do so. The source of such commencements is necessarily to be sought in different variations, which remain unaffected by selection until they have taken such a form as to become utilisable in the struggle for existence. It is not essential to Darwin's theory that anything more should be assumed than the facts of heredity, variation, and unlimited multiplication; and the validity of the deductive reasoning as to the effect of the last (that is, of the struggle for existence which it involves) upon the varieties resulting from the operation of the former. Nor is it essential that one should take up any particular position in regard to the mode of variation, whether, for example, it takes place _per saltum_ or gradually; whether it is definite in character or indefinite. Still less are those who accept the theory bound to any particular views as to the causes of heredity or of variation. That Darwin held strong opinions on some or all of these points may be quite true; but, so far as the theory is concerned, they must be regarded as _obiter dicta_. With respect to the causes of variation, Darwin's opinions are, from first to last, put forward altogether tentatively. In the first edition of the "Origin," he attributes the strongest influence to changes in the conditions of life of parental organisms, which he appears to think act on the germ through the intermediation of the sexual organs. He points out, over and over again, that habit, use, disuse, and the direct influence of conditions have some effect, but he does not think it great, and he draws attention to the difficulty of distinguishing between effects of these agencies and those of selection. There is, however, one class of variations which he withdraws from the direct influence of selection, namely, the variations in the fertility of the sexual union of more or less closely allied forms. He regards less fertility, or more or less complete sterility, as "incidental to other acquired differences." (_Ibid_., p. 245.) Considering the difficulties which surround the question of the causes of variation, it is not to be wondered at, that Darwin should have inclined, sometimes, rather more to one and, sometimes, rather more to another of the possible alternatives. There is little difference between the last edition of the "Origin" (1872) and the first on this head. In 1876, however, he writes to Moritz Wagner, "In my opinion, the greatest error which I have committed has been not allowing sufficient weight to the direct action of the environments, i.e., food, climate, &c., independently of natural selection. ...When I wrote the 'Origin,' and for some years afterwards, I could find little good evidence of the direct action of the environment; now there is a large body of evidence, and your case of the Saturnia is one of the most remarkable of which I have heard." (III, p. 159.) But there is really nothing to prevent the most tenacious adherent to the theory of natural selection from taking any view he pleases as to the importance of the direct influence of conditions and the hereditary transmissibility of the modifications which they produce. In fact, there is a good deal to be said for the view that the so-called direct influence of conditions is itself a case of selection. Whether the hypothesis of Pangenesis be accepted or rejected, it can hardly be doubted that the struggle for existence goes on not merely between distinct organisms, but between the physiological units of which each organism is composed, and that changes in external conditions favour some and hinder others. After a short stay in Cambridge, Darwin resided in London for the first five years which followed his return to England; and for three years, he held the post of Secretary to the Geological Society, though he shared to the full his friend Lyell's objection to entanglement in such engagements. In fact, he used to say in later life, more than half in earnest, that he gave up hoping for work from men who accepted official duties and, especially, Government appointments. Happily for him, he was exempted from the necessity of making any sacrifice of this kind, but an even heavier burden was laid upon him. During the earlier half of his voyage Darwin retained the vigorous health of his boyhood, and indeed proved himself to be exceptionally capable of enduring fatigue and privation. An anomalous but severe disorder, which laid him up for several weeks at Valparaiso in 1834, however, seems to have left its mark on his constitution; and, in the later years of his London life, attacks of illness, usually accompanied by severe vomiting and great prostration of strength, became frequent. As he grew older, a considerable part of every day, even at his best times, was spent in misery; while, not unfrequently, months of suffering rendered work of any kind impossible. Even Darwin's remarkable tenacity of purpose and methodical utilisation of every particle of available energy could not have enabled him to achieve a fraction of the vast amount of labour he got through, in the course of the following forty years, had not the wisest and the most loving care unceasingly surrounded him from the time of his marriage in 1839. As early as 1842, the failure of health was so marked that removal from London became imperatively necessary; and Darwin purchased a house and grounds at Down, a solitary hamlet in Kent, which was his home for the rest of his life. Under the strictly regulated conditions of a valetudinarian existence, the intellectual activity of the invalid might have put to shame most healthy men; and, so long as he could hold his head up, there was no limit to the genial kindness of thought and action for all about him. Those friends who were privileged to share the intimate life of the household at Down have an abiding memory of the cheerful restfulness which pervaded and characterised it. After mentioning his settlement at Down, Darwin writes in his Autobiography:-- "My chief enjoyment and sole employment throughout life has been scientific work; and the excitement from such work makes me, for the time, forget, or drives quite away, my daily discomfort. I have, therefore, nothing to record during the rest of my life, except the publication of my several books." (I, p. 79.) Of such works published subsequently to 1859, several are monographic discussions of topics briefly dealt with in the "Origin," which, it must always be recollected, was considered by the author to be merely an abstract of an _opus majus_. The earliest of the books which may be placed in this category, "On the Various Contrivances by which Orchids are Fertilised by Insects," was published in 1862, and whether we regard its theoretical significance, the excellence of the observations and the ingenuity of the reasonings which it records, or the prodigious mass of subsequent investigation of which it has been the parent, it has no superior in point of importance. The conviction that no theory of the origin of species could be satisfactory which failed to offer an explanation of the way in which mechanisms involving adaptations of structure and function to the performance of certain operations are brought about, was, from the first, dominant in Darwin's mind. As has been seen, he rejected Lamarck's views because of their obvious incapacity to furnish such an explanation in the case of the great majority of animal mechanisms, and in that of all those presented by the vegetable world. So far back as 1793, the wonderful work of Sprengel had established, beyond any reasonable doubt, the fact that, in a large number of cases, a flower is a piece of mechanism the object of which is to convert insect visitors into agents of fertilisation. Sprengel's observations had been most undeservedly neglected and well-nigh forgotten; but Robert Brown having directed Darwin's attention to them in 1841, he was attracted towards the subject, and verified many of Sprengel's statements. (III, p. 258.) It may be doubted whether there was a living botanical specialist, except perhaps Brown, who had done as much. If, however, adaptations of this kind were to be explained by natural selection, it was necessary to show that the plants which were provided with mechanisms for ensuring the aid of insects as fertilisers, were by so much the better fitted to compete with their rivals. This Sprengel had not done. Darwin had been attending to cross fertilisation in plants so far back as 1839, from having arrived, in the course of his speculations on the origin of species, at the conviction "that crossing played an important part in keeping specific forms constant" (I, p. 90). The further development of his views on the importance of cross fertilisation appears to have taken place between this time and 1857, when he published his first papers on the fertilisation of flowers in the "Gardener's Chronicle." If the conclusion at which he ultimately arrived, that cross fertilisation is favourable to the fertility of the parent and to the vigour of the offspring, is correct, then it follows that all those mechanisms which hinder self-fertilisation and favour crossing must be advantageous in the struggle for existence; and, the more perfect the action of the mechanism, the greater the advantage. Thus the way lay open for the operation of natural selection in gradually perfecting the flower as a fertilisation-trap. Analogous reasoning applies to the fertilising insect. The better its structure is adapted to that of the trap, the more will it be able to profit by the bait, whether of honey or of pollen, to the exclusion of its competitors. Thus, by a sort of action and reaction, a two-fold series of adaptive modifications will be brought about. In 1865, the important bearing of this subject on his theory led Darwin to commence a great series of laborious and difficult experiments on the fertilisation of plants, which occupied him for eleven years, and furnished him with the unexpectedly strong evidence in favour of the influence of crossing which he published in 1876, under the title of "The Effects of Cross and Self Fertilisation in the Vegetable Kingdom." Incidentally, as it were, to this heavy piece of work, he made the remarkable series of observations on the different arrangements by which crossing is favoured and, in many cases, necessitated, which appeared in the work on "The Different Forms of Flowers in Plants of the same Species" in 1877. In the course of the twenty years during which Darwin was thus occupied in opening up new regions of investigation to the botanist and showing the profound physiological significance of the apparently meaningless diversities of floral structure, his attention was keenly alive to any other interesting phenomena of plant life which came in his way. In his correspondence, he not unfrequently laughs at himself for his ignorance of systematic botany; and his acquaintance with vegetable anatomy and physiology was of the slenderest. Nevertheless, if any of the less common features of plant life came under his notice, that imperious necessity of seeking for causes which nature had laid upon him, impelled, and indeed compelled, him to inquire the how and the why of the fact, and its bearing on his general views. And as, happily, the atavic tendency to frame hypotheses was accompanied by an equally strong need to test them by well-devised experiments, and to acquire all possible information before publishing his results, the effect was that he touched no topic without elucidating it. Thus the investigation of the operations of insectivorous plants, embodied in the work on that topic published in 1875, was started fifteen years before, by a passing observation made during one of Darwin's rare holidays. "In the summer of 1860, I was idling and resting near Hartfield, where two species of Drosera abound; and I noticed that numerous insects had been entrapped by the leaves. I carried home some plants, and on giving them some insects saw the movements of the tentacles, and this made me think it possible that the insects were caught for some special purpose. Fortunately, a crucial test occurred to me, that of placing a large number of leaves in various nitrogenous and non-nitrogenous fluids of equal density; and as soon as I found that the former alone excited energetic movements, it was obvious that here was a fine new field for investigation." (I, p. 95.) The researches thus initiated led to the proof that plants are capable of secreting a digestive fluid like that of animals, and of profiting by the result of digestion; whereby the peculiar apparatuses of the insectivorous plants were brought within the scope of natural selection. Moreover, these inquiries widely enlarged our knowledge of the manner in which stimuli are transmitted in plants, and opened up a prospect of drawing closer the analogies between the motor processes of plants and those of animals. So with respect to the books on "Climbing Plants" (1875), and on the "Power of Movement in Plants" (1880), Darwin says;-- "I was led to take up this subject by reading a short paper by Asa Gray, published in 1858. He sent me some seeds, and on raising some plants I was so much fascinated and perplexed by the revolving movements of the tendrils and stems, which movements are really very simple, though appearing at first sight very complex, that I procured various other kinds of climbing plants and studied the whole subject.... Some of the adaptations displayed by climbing plants are as beautiful as those of orchids for ensuring cross-fertilisation." (I, p. 93.) In the midst of all this amount of work, remarkable alike for its variety and its importance, among plants, the animal kingdom was by no means neglected. A large moiety of "The Variation of Animals and Plants under Domestication" (1868), which contains the _pièces justificatives_ of the first chapter of the "Origin," is devoted to domestic animals, and the hypothesis of "pangenesis" propounded in the second volume applies to the whole living world. In the "Origin" Darwin throws out some suggestions as to the causes of variation, but he takes heredity, as it is manifested by individual organisms, for granted, as an ultimate fact; pangenesis is an attempt to account for the phenomena of heredity in the organism, on the assumption that the physiological units of which the organism is composed give off gemmules, which, in virtue of heredity, tend to reproduce the unit from which they are derived. That Darwin had the application of his theory to the origin of the human species clearly in his mind in 1859, is obvious from a passage in the first edition of "The Origin of Species." (Ed. I, p. 488.) "In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history." It is one of the curiosities of scientific literature, that, in the face of this plain declaration, its author should have been charged with concealing his opinions on the subject of the origin of man. But he reserved the full statement of his views until 1871, when the "Descent of Man" was published. The "Expression of the Emotions" (originally intended to form only a chapter in the "Descent of Man") grew into a separate volume, which appeared in 1872. Although always taking a keen interest in geology, Darwin naturally found no time disposable for geological work, even had his health permitted it, after he became seriously engaged with the great problem of species. But the last of his labours is, in some sense, a return to his earliest, inasmuch as it is an expansion of a short paper read before the Geological Society more than forty years before, and, as he says, "revived old geological thoughts" (I, p. 98). In fact, "The Formation of Vegetable Mould through the Action of Worms," affords as striking an example of the great results produced by the long-continued operation of small causes as even the author of the "Principles of Geology" could have desired. In the early months of 1882 Darwin's health underwent a change for the worse; attacks of giddiness and fainting supervened, and on the 19th of April he died. On the 24th, his remains were interred in Westminster Abbey, in accordance with the general feeling that such a man as he should not go to the grave without some public recognition of the greatness of his work. Mr. Darwin became a Fellow of the Royal Society in 1839; one of the Royal Medals was awarded to him in 1853, and he received the Copley Medal in 1864. The "Life and Letters," edited with admirable skill and judgment by Mr. Francis Darwin, gives a full and singularly vivid presentment of his father's personal character, of his mode of work, and of the events of his life. In the present brief obituary notice, the writer has attempted nothing more than to select and put together those facts which enable us to trace the intellectual evolution of one of the greatest of the many great men of science whose names adorn the long roll of the Fellows of the Royal Society. XI ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE [_Six Lectures to Working Men_.--1863.] I. THE PRESENT CONDITION OF ORGANIC NATURE When it was my duty to consider what subject I would select for the six lectures which I shall now have the pleasure of delivering to you, it occurred to me that I could not do better than endeavour to put before you in a true light, or in what I might perhaps with more modesty call, that which I conceive myself to be the true light, the position of a book which has been more praised and more abused, perhaps, than any book which has appeared for some years;--I mean Mr. Darwin's work on the "Origin of Species." That work, I doubt not, many of you have read; for I know the inquiring spirit which is rife among you. At any rate, all of you will have heard of it,--some by one kind of report and some by another kind of report; the attention of all and the curiosity of all have been probably more or less excited on the subject of that work. All I can do, and all I shall attempt to do, is to put before you that kind of judgment which has been formed by a man, who, of course, is liable to judge erroneously; but, at any rate, of one whose business and profession it is to form judgments upon questions of this nature. And here, as it will always happen when dealing with an extensive subject, the greater part of my course--if, indeed, so small a number of lectures can be properly called a course--must be devoted to preliminary matters, or rather to a statement of those facts and of those principles which the work itself dwells upon, and brings more or less directly before us. I have no right to suppose that all or any of you are naturalists; and, even if you were, the misconceptions and misunderstandings prevalent even among naturalists, on these matters, would make it desirable that I should take the course I now propose to take,--that I should start from the beginning,--that I should endeavour to point out what is the existing state of the organic world--that I should point out its past condition,--that I should state what is the precise nature of the undertaking which Mr. Darwin has taken in hand; that I should endeavour to show you what are the only methods by which that undertaking can be brought to an issue, and to point out to you how far the author of the work in question has satisfied those conditions, how far he has not satisfied them, how far they are satisfiable by man, and how far they are not satisfiable by man. To-night, in taking up the first part of the question, I shall endeavour to put before you a sort of broad notion of our knowledge of the condition of the living world. There are many ways of doing this. I might deal with it pictorially and graphically. Following the example of Humboldt in his "Aspects of Nature," I might endeavour to point out the infinite variety of organic life in every mode of its existence, with reference to the variations of climate and the like; and such an attempt would be fraught with interest to us all; but considering the subject before us, such a course would not be that best calculated to assist us. In an argument of this kind we must go further and dig deeper into the matter; we must endeavour to look into the foundations of living Nature, if I may so say, and discover the principles involved in some of her most secret operations. I propose, therefore, in the first place, to take some ordinary animal with which you are all familiar, and by easily comprehensible and obvious examples drawn from it, to show what are the kind of problems which living beings in general lay before us; and I shall then show you that the same problems are laid open to us by all kinds of living beings. But, first, let me say in what sense I have used the words "organic nature." In speaking of the causes which lead to our present knowledge of organic nature, I have used it almost as an equivalent of the word "living," and for this reason,--that in almost all living beings you can distinguish several distinct portions set apart to do particular things and work in a particular way. These are termed "organs," and the whole together is called "organic." And as it is universally characteristic of them, the term "organic" has been very conveniently employed to denote the whole of living nature,--the whole of the plant world, and the whole of the animal world. Few animals can be more familiar to you than that whose skeleton is shown on our diagram. You need not bother yourselves with this "_Equus caballus_" written under it; that is only the Latin name of it, and does not make it any better. It simply means the common horse. Suppose we wish to understand all about the horse. Our first object must be to study the structure of the animal. The whole of his body is inclosed within a hide, a skin covered with hair; and if that hide or skin be taken off, we find a great mass of flesh, or what is technically called muscle, being the substance which by its power of contraction enables the animal to move. These muscles move the hard parts one upon the other, and so give that strength and power of motion which renders the horse so useful to us in the performance of those services in which we employ him. And then, on separating and removing the whole of this skin and flesh, you have a great series of bones, hard structures, bound together with ligaments, and forming the skeleton which is represented here. In that skeleton there are a number of parts to be recognised. The long series of bones, beginning from the skull and ending in the tail, is called the spine, and those in front are the ribs; and then there are two pairs of limbs, one before and one behind; and there are what we all know as the fore-legs and the hind-legs. If we pursue our researches into the interior of this animal, we find within the framework of the skeleton a great cavity, or rather, I should say, two great cavities,--one cavity beginning in the skull and running through the neck-bones, along the spine, and ending in the tail, containing the brain and the spinal marrow, which are extremely important organs. The second great cavity, commencing with the mouth, contains the gullet, the stomach, the long intestine, and all the rest of those internal apparatus which are essential for digestion; and then in the same great cavity, there are lodged the heart and all the great vessels going from it; and, besides that, the organs of respiration--the lungs: and then the kidneys, and the organs of reproduction, and so on. Let us now endeavour to reduce this notion of a horse that we now have, to some such kind of simple expressions as can be at once, and without difficulty, retained in the mind, apart from all minor details. If I make a transverse section, that is, if I were to saw a dead horse across, I should find that, if I left out the details, and supposing I took my section through the anterior region, and through the fore-limbs, I should have here this kind of section of the body (Fig. 1). [Illustration: Fig. 1] Here would be the upper part of the animal--that great mass of bones that we spoke of as the spine (_a_, Fig. 1). Here I should have the alimentary canal (_b_, Fig. 1). Here I should have the heart (_c_, Fig. 1); and then you see, there would be a kind of double tube, the whole being inclosed within the hide; the spinal marrow would be placed in the upper tube (_a_, Fig. 1), and in the lower tube (_d d_, Fig. 1), there would be the alimentary canal (_b_), and the heart (_e_); and here I shall have the legs proceeding from each side. For simplicity's sake, I represent them merely as stumps (_e e_, Fig. 1). Now that is a horse--as mathematicians would say--reduced to its most simple expression. Carry that in your minds, if you please, as a simplified idea of the structure of the horse. The considerations which I have now put before you belong to what we technically call the "Anatomy" of the horse. Now, suppose we go to work upon these several parts,--flesh and hair, and skin and bone, and lay open these various organs with our scalpels, and examine them by means of our magnifying-glasses, and see what we can make of them. We shall find that the flesh is made up of bundles of strong fibres The brain and nerves, too, we shall find are made up of fibres, and these queer-looking things that are called ganglionic corpuscles. If we take a slice of the bone and examine it, we shall find that it is very like this diagram of a section of the bone of on ostrich, though differing, of course, in some details; and if we take any part whatsoever of the tissue, and examine it, we shall find it all has a minute structure, visible only under the microscope. All these parts constitute microscopic anatomy or "Histology." These parts are constantly being changed; every part is constantly growing, decaying, and being replaced during the life of the animal. The tissue is constantly replaced by new material; and if you go back to the young state of the tissue in the case of muscle, or in the case of skin, or any of the organs I have mentioned, you will find that they all come under the same condition. Every one of these microscopic filaments and fibres (I now speak merely of the general character of the whole process)--every one of these parts--could be traced down to some modification of a tissue which can be readily divided into little particles of fleshy matter, of that substance which is composed of the chemical elements, carbon, hydrogen, oxygen, and nitrogen, having such a shape as this (Fig. 2). These particles, into which all primitive tissues break up, are called cells. If I were to make a section of a piece of the skin of my hand, I should find that it was made up of these cells. If I examine the fibres which form the various organs of all living animals, I should find that all of them, at one time or other, had been formed out of a substance consisting of similar elements; so that you see, just as we reduced the whole body in the gross to that sort of simple expression given in Fig. 1, so we may reduce the whole of the microscopic structural elements to a form of even greater simplicity; just as the plan of the whole body may be so represented in a sense (Fig. 1), so the primary structure of every tissue may be represented by a mass of cells (Fig. 2). [Illustration: Fig. 2.] Having thus, in this sort of general way, sketched to you what I may call, perhaps, the architecture of the body of the horse (what we term technically its Morphology), I must now turn to another aspect. A horse is not a mere dead structure: it is an active, living, working machine. Hitherto we have, as it were, been looking at a steam-engine with the fires out, and nothing in the boiler; but the body of the living animal is a beautifully-formed active machine, and every part has its different work to do in the working of that machine, which is what we call its life. The horse, if you see him after his day's work is done, is cropping the grass in the fields, as it may be, or munching the oats in his stable. What is he doing? His jaws are working as a mill--and a very complex mill too--grinding the corn, or crushing the grass to a pulp. As soon as that operation has taken place, the food is passed down to the stomach, and there it is mixed with the chemical fluid called the gastric juice, a substance which has the peculiar property of making soluble and dissolving out the nutritious matter in the grass, and leaving behind those parts which are not nutritious; so that you have, first, the mill, then a sort of chemical digester; and then the food, thus partially dissolved, is carried back by the muscular contractions of the intestines into the hinder parts of the body, while the soluble portions are taken up into the blood. The blood is contained in a vast system of pipes, spreading through the whole body, connected with a force-pump,--the heart,--which, by its position and by the contractions of its valves, keeps the blood constantly circulating in one direction, never allowing it to rest; and then, by means of this circulation of the blood, laden as it is with the products of digestion, the skin, the flesh, the hair, and every other part of the body, draws from it that which it wants, and every one of these organs derives those materials which are necessary to enable it to do its work. The action of each of these organs, the performance of each of these various duties, involve in their operation a continual absorption of the matters necessary for their support, from the blood and a constant formation of waste products, which are returned to the blood, and conveyed by it to the lungs and the kidneys, which are organs that have allotted to them the office of extracting, separating, and getting rid of these waste products; and thus the general nourishment, labour, and repair of the whole machine are kept up with order and regularity. But not only is it a machine which feeds and appropriates to its own support the nourishment necessary to its existence--it is an engine for locomotive purposes. The horse desires to go from one place to another; and to enable it to do this, it has those strong contractile bundles of muscles attached to the bones of its limbs, which are put in motion by means of a sort of telegraphic apparatus formed by the brain and the great spinal cord running through the spine or backbone; and to this spinal cord are attached a number of fibres termed nerves, which proceed to all parts of the structure. By means of these the eyes, nose, tongue, and skin--all the organs of perception--transmit impressions or sensations to the brain, which acts as a sort of great central telegraph-office, receiving impressions and sending messages to all parts of the body, and putting in motion the muscles necessary to accomplish any movement that maybe desired. So that you have here an extremely complex and beautifully-proportioned machine, with all its parts working harmoniously together towards one common object--the preservation of the life of the animal. Now, note this: the horse makes up its waste by feeding, and its food is grass or oats, or perhaps other vegetable products; therefore, in the long run, the source of all this complex machinery lies in the vegetable kingdom. But where does the grass, or the oat, or any other plant obtain this nourishing food-producing material? At first it is a little seed, which soon begins to draw into itself from the earth and the surrounding air matters which in themselves contain no vital properties whatever; it absorbs into its own substance water, an inorganic body; it draws into its substance carbonic acid, an inorganic matter; and ammonia, another inorganic matter, found in the air; and then, by some wonderful chemical process, the details of which chemists do not yet understand, though they are near foreshadowing them, it combines them into one substance, which is known to us as "Protein," a complex compound of carbon, hydrogen, oxygen, and nitrogen, which alone possesses the property of manifesting vitality and of permanently supporting animal life. So that, you see, the waste products of the animal economy, the effete materials which are continually being thrown off by all living beings, in the form of organic matters, are constantly replaced by supplies of the necessary repairing and rebuilding materials drawn from the plants, which in their turn manufacture them, so to speak, by a mysterious combination of those same inorganic materials. Let us trace out the history of the horse in another direction. After a certain time, as the result of sickness or disease, the effect of accident, or the consequence of old age, sooner or later, the animal dies. The multitudinous operations of this beautiful mechanism flag in their performance, the horse loses its vigour, and after passing through the curious series of changes comprised in its formation and preservation, it finally decays, and ends its life by going back into that inorganic world from which all but an inappreciable fraction of its substance was derived. Its bones become mere carbonate and phosphate of lime; the matter of its flesh, and of its other parts, becomes, in the long run, converted into carbonic acid, into water, and into ammonia. You will now, perhaps, understand the curious relation of the animal with the plant, of the organic with the inorganic world, which is shown in this diagram. [Illustration: Inorganic World Fig. 3.] The plant gathers these inorganic materials together and makes them up into its own substance. The animal eats the plant and appropriates the nutritious portions to its own sustenance, rejects and gets rid of the useless matters; and, finally, the animal itself dies, and its whole body is decomposed and returned into the inorganic world. There is thus a constant circulation from one to the other, a continual formation of organic life from inorganic matters, and as constant a return of the matter of living bodies to the inorganic world; so that the materials of which our bodies are composed are largely, in all probability, the substances which constituted the matter of long extinct creations, but which have in the interval constituted a part of the inorganic world. Thus we come to the conclusion, strange at first sight, that the MATTER constituting the living world is identical with that which forms the inorganic world. And not less true is it that, remarkable as are the powers or, in other words, as are the FORCES which are exerted by living beings, yet all these forces are either identical with those which exist in the inorganic world, or they are convertible into them; I mean in just the same sense as the researches of physical philosophers have shown that heat is convertible into electricity, that electricity is convertible into magnetism, magnetism into mechanical force or chemical force, and any one of them with the other, each being measurable in terms of the other,--even so, I say, that great law is applicable to the living world. Consider why is the skeleton of this horse capable of supporting the masses of flesh and the various organs forming the living body, unless it is because of the action of the same forces of cohesion which combines together the particles of matter composing this piece of chalk? What is there in the muscular contractile power of the animal but the force which is expressible, and which is in a certain sense convertible, into the force of gravity which it overcomes? Or, if you go to more hidden processes, in what does the process of digestion differ from those processes which are carried on in the laboratory of the chemist? Even if we take the most recondite and most complex operations of animal life--those of the nervous system, these of late years have been shown to be--I do not say identical in any sense with the electrical processes--but this has been shown, that they are in some way or other associated with them; that is to say, that every amount of nervous action is accompanied by a certain amount of electrical disturbance in the particles of the nerves in which that nervous action is carried on. In this way the nervous action is related to electricity in the same way that heat is related to electricity; and the same sort of argument which demonstrates the two latter to be related to one another shows that the nervous forces are correlated to electricity; for the experiments of M. Dubois Reymond and others have shown that whenever a nerve is in a state of excitement, sending a message to the muscles or conveying an impression to the brain, there is a disturbance of the electrical condition of that nerve which does not exist at other times; and there are a number of other facts and phenomena of that sort; so that we come to the broad conclusion that not only as to living matter itself, but as to the forces that matter exerts, there is a close relationship between the organic and the inorganic world--the difference between them arising from the diverse combination and disposition of identical forces, and not from any primary diversity, so far as we can see. I said just now that the horse eventually died and became converted into the same inorganic substances from whence all but an inappreciable fraction of its substance demonstrably originated, so that the actual wanderings of matter are as remarkable as the transmigrations of the soul fabled by Indian tradition. But before death has occurred, in the one sex or the other, and in fact in both, certain products or parts of the organism have been set free, certain parts of the organisms of the two sexes have come into contact with one another, and from that conjunction, from that union which then takes place, there results the formation of a new being. At stated times the mare, from a particular part of the interior of her body, called the ovary, gets rid of a minute particle of matter comparable in all essential respects with that which we called a cell a little while since, which cell contains a kind of nucleus in its centre, surrounded by a clear space and by a viscid mass of protein substance (Fig. 2); and though it is different in appearance from the eggs which we are mostly acquainted with, it is really an egg. After a time this minute particle of matter, which may only be a small fraction of a grain in weight, undergoes a series of changes,--wonderful, complex changes. Finally, upon its surface there is fashioned a little elevation, which afterwards becomes divided and marked by a groove. The lateral boundaries of the groove extend upwards and downwards, and at length give rise to a double tube. In the upper and smaller tube the spinal marrow and brain are fashioned; in the lower, the alimentary canal and heart; and at length two pairs of buds shoot out at the sides of the body, and they are the rudiments of the limbs. In fact a true drawing of a section of the embryo in this state would in all essential respects resemble that diagram of a horse reduced to its simplest expression, which I first placed before you (Fig. 1). Slowly and gradually these changes take place. The whole of the body, at first, can be broken up into "cells," which become in one place metamorphosed into muscle,--in another place into gristle and bone,--in another place into fibrous tissue,--and in another into hair; every part becoming gradually and slowly fashioned, as if there were an artificer at work in each of these complex structures that I have mentioned. This embryo, as it is called, then passes into other conditions. I should tell you that there is a time when the embryos of neither dog, nor horse, nor porpoise, nor monkey, nor man, can be distinguished by any essential feature one from the other; there is a time when they each and all of them resemble this one of the dog. But as development advances, all the parts acquire their speciality, till at length you have the embryo converted into the form of the parent from which it started. So that you see, this living animal, this horse, begins its existence as a minute particle of nitrogenous matter, which, being supplied with nutriment (derived, as I have shown, from the inorganic world), grows up according to the special type and construction of its parents, works and undergoes a constant waste, and that waste is made good by nutriment derived from the inorganic world; the waste given off in this way being directly added to the inorganic world. Eventually the animal itself dies, and, by the process of decomposition, its whole body is returned to those conditions of inorganic matter in which its substance originated. This, then, is that which is true of every living form, from the lowest plant to the highest animal--to man himself. You might define the life of every one in exactly the same terms as those which I have now used; the difference between the highest and the lowest being simply in the complexity of the developmental changes, the variety of the structural forms, and the diversity of the physiological functions which are exerted by each. If I were to take an oak tree, as a specimen of the plant world, I should find that it originated in an acorn, which, too, commenced in a cell; the acorn is placed in the ground, and it very speedily begins to absorb the inorganic matters I have named, adds enormously to its bulk, and we can see it, year after year, extending itself upward and downward, attracting and appropriating to itself inorganic materials, which it vivifies, and eventually, as it ripens, gives off its own proper acorns, which again run the same course. But I need not multiply examples,--from the highest to the lowest the essential features of life are the same as I have described in each of these cases. So much, then, for these particular features of the organic world, which you can understand and comprehend, so long as you confine yourself to one sort of living being, and study that only. But, as you know, horses are not the only living creatures in the world; and again, horses, like all other animals, have certain limits--are confined to a certain area on the surface of the earth on which we live,--and, as that is the simpler matter, I may take that first. In its wild state, and before the discovery of America, when the natural state of things was interfered with by the Spaniards, the horse was only to be found in parts of the earth which are known to geographers as the Old World; that is to say, you might meet with horses in Europe, Asia, or Africa; but there were none in Australia, and there were none whatsoever in the whole continent of America, from Labrador down to Cape Horn. This is an empirical fact, and it is what is called, stated in the way I have given it you, the "Geographical Distribution" of the horse. Why horses should be found in Europe, Asia, and Africa, and not in America, is not obvious; the explanation that the conditions of life in America are unfavourable to their existence, and that, therefore, they had not been created there, evidently does not apply; for when the invading Spaniards, or our own yeomen farmers, conveyed horses to these countries for their own use, they were found to thrive well and multiply very rapidly; and many are even now running wild in those countries, and in a perfectly natural condition. Now, suppose we were to do for every animal what we have here done for the horse,--that is, to mark off and distinguish the particular district or region to which each belonged; and supposing we tabulated all these results, that would be called the Geographical Distribution of animals, while a corresponding study of plants would yield as a result the Geographical Distribution of plants. I pass on from that now, as I merely wished to explain to you what I meant by the use of the term "Geographical Distribution." As I said, there is another aspect, and a much more important one, and that is, the relations of the various animals to one another. The horse is a very well-defined matter-of-fact sort of animal, and we are all pretty familiar with its structure. I dare say it may have struck you, that it resembles very much no other member of the animal kingdom, except perhaps the zebra or the ass. But let me ask you to look along these diagrams. Here is the skeleton of the horse, and here the skeleton of the dog. You will notice that we have in the horse a skull, a backbone and ribs, shoulder-blades and haunch-bones. In the fore-limb, one upper arm-bone, two fore arm-bones, wrist-bones (wrongly called knee), and middle hand-bones, ending in the three bones of a finger, the last of which is sheathed in the horny hoof of the fore-foot: in the hind-limb, one thigh-bone, two leg-bones, ankle-bones, and middle foot-bones, ending in the three bones of a toe, the last of which is encased in the hoof of the hind-foot. Now turn to the dog's skeleton. We find identically the same bones, but more of them, there being more toes in each foot, and hence more toe-bones. Well, that is a very curious thing! The fact is that the dog and the horse--when one gets a look at them without the outward impediments of the skin--are found to be made in very much the same sort of fashion. And if I were to make a transverse section of the dog, I should find the same organs that I have already shown you as forming parts of the horse. Well, here is another skeleton--that of a kind of lemur--you see he has just the same bones; and if I were to make a transverse section of it, it would be just the same again. In your mind's eye turn him round, so as to put his backbone in a position inclined obliquely upwards and forwards, just as in the next three diagrams, which represent the skeletons of an orang, a chimpanzee, and a gorilla, and you find you have no trouble in identifying the bones throughout; and lastly turn to the end of the series, the diagram representing a man's skeleton, and still you find no great structural feature essentially altered. There are the same bones in the same relations. From the horse we pass on and on, with gradual steps until we arrive at last at the highest known forms. On the other hand, take the other line of diagrams, and pass from the horse downwards in the scale to this fish; and still, though the modifications are vastly greater, the essential framework of the organisation remains unchanged. Here, for instance, is a porpoise: here is its strong backbone, with the cavity running through it, which contains the spinal cord; here are the ribs, here the shoulder-blade; here is the little short upper-arm bone, here are the two forearm bones, the wrist-bone, and the finger-bones. Strange, is it not, that the porpoise should have in this queer-looking affair--its flapper (as it is called), the same fundamental elements as the fore-leg of the horse or the dog, or the ape or man; and here you will notice a very curious thing,--the hinder limbs are absent. Now, let us make another jump. Let us go to the codfish: here you see is the forearm, in this large pectoral fin--carrying your mind's eye onward from the flapper of the porpoise. And here you have the hinder limbs restored in the shape of these ventral fins. If I were to make a transverse section of this, I should find just the same organs that we have before noticed. So that, you see, there comes out this strange conclusion as the result of our investigations, that the horse, when examined and compared with other animals, is found by no means to stand alone in Nature; but that there are an enormous number of other creatures which have backbones, ribs, and legs, and other parts arranged in the same general manner, and in all their formation exhibiting the same broad peculiarities. I am sure that you cannot have followed me even in this extremely elementary exposition of the structural relations of animals, without seeing what I have been driving at all through, which is, to show you that, step by step, naturalists have come to the idea of a unity of plan, or conformity of construction, among animals which appeared at first sight to be extremely dissimilar. And here you have evidence of such a unity of plan among all the animals which have backbones, and which we technically call _Vertebrata_. But there are multitudes of other animals, such as crabs, lobsters, spiders, and so on, which we term _Annulosa_. In these I could not point out to you the parts that correspond with those of the horse,--the backbone, for instance,--as they are constructed upon a very different principle, which is also common to all of them; that is to say, the lobster, the spider, and the centipede, have a common plan running through their whole arrangement, in just the same way that the horse, the dog, and the porpoise assimilate to each other. Yet other creatures--whelks, cuttlefishes, oysters, snails, and all their tribe (_Mollusca_)--resemble one another in the same way, but differ from both _Vertebrata_ and _Annulosa_; and the like is true of the animals called _Coelenterata_ (Polypes) and _Protozoa_ (animalcules and sponges). Now, by pursuing this sort of comparison, naturalists have arrived at the conviction that there are,--some think five, and some seven,--but certainly not more than the latter number--and perhaps it is simpler to assume five--distinct plans or constructions in the whole of the animal world; and that the hundreds of thousands of species of creatures on the surface of the earth, are all reducible to those five, or, at most, seven, plans of organisation. But can we go no further than that? When one has got so far, one is tempted to go on a step and inquire whether we cannot go back yet further and bring down the whole to modifications of one primordial unit. The anatomist cannot do this; but if he call to his aid the study of development, he can do it. For we shall find that, distinct as those plans are, whether it be a porpoise or man, or lobster, or any of those other kinds I have mentioned, every one begins its existence with one and the same primitive form,--that of the egg, consisting, as we have seen, of a nitrogenous substance, having a small particle or nucleus in the centre of it. Furthermore, the earlier changes of each are substantially the same. And it is in this that lies that true "unity of organisation" of the animal kingdom which has been guessed at and fancied for many years; but which it has been left to the present time to be demonstrated by the careful study of development. But is it possible to go another step further still, and to show that in the same way the whole of the organic world is reducible to one primitive condition of form? Is there among the plants the same primitive form of organisation, and is that identical with that of the animal kingdom? The reply to that question, too, is not uncertain or doubtful. It is now proved that every plant begins its existence under the same form; that is to say, in that of a cell--a particle of nitrogenous matter having substantially the same conditions. So that if you trace back the oak to its first germ, or a man, or a horse, or lobster, or oyster, or any other animal you choose to name, you shall find each and all of these commencing their existence in forms essentially similar to each other; and, furthermore, that the first processes of growth, and many of the subsequent modifications, are essentially the same in principle in almost all. In conclusion, let me, in a few words, recapitulate the positions which I have laid down. And you must understand that I have not been talking mere theory; I have been speaking of matters which are as plainly demonstrable as the commonest propositions of Euclid--of facts that must form the basis of all speculations and beliefs in Biological science. We have gradually traced down all organic forms, or, in other words, we have analysed the present condition of animated nature, until we found that each species took its origin in a form similar to that under which all the others commenced their existence. We have found the whole of the vast array of living forms with which we are surrounded, constantly growing, increasing, decaying and disappearing; the animal constantly attracting, modifying, and applying to its sustenance the matter of the vegetable kingdom, which derived its support from the absorption and conversion of inorganic matter. And so constant and universal is this absorption, waste, and reproduction, that it may be said with perfect certainty that there is left in no one of our bodies at the present moment a millionth part of the matter of which they were originally formed! We have seen, again, that not only is the living matter derived from the inorganic world, but that the forces of that matter are all of them correlative with and convertible into those of inorganic nature. This, for our present purposes, is the best view of the present condition of organic nature which I can lay before you: it gives you the great outlines of a vast picture, which you must fill up by your own study. In the next lecture I shall endeavour in the same way to go back into the past, and to sketch in the same broad manner the history of life in epochs preceding our own. II. THE PAST CONDITION OF ORGANIC NATURE In the lecture which I delivered last Monday evening, I endeavoured to sketch in a very brief manner, but as well as the time at my disposal would permit, the present condition of organic nature, meaning by that large title simply an indication of the great, broad, and general principles which are to be discovered by those who look attentively at the phenomena of organic nature as at present displayed. The general result of our investigations might be summed up thus: we found that the multiplicity of the forms of animal life, great as that may be, may be reduced to a comparatively few primitive plans or types of construction; that a further study of the development of those different forms revealed to us that they were again reducible, until we at last brought the infinite diversity of animal, and even vegetable life, down to the primordial form of a single cell. We found that our analysis of the organic world, whether animals or plants, showed, in the long run, that they might both be reduced into, and were, in fact, composed of, the same constituents. And we saw that the plant obtained the materials constituting its substance by a peculiar combination of matters belonging entirely to the inorganic world; that, then, the animal was constantly appropriating the nitrogenous matters of the plant to its own nourishment, and returning them back to the inorganic world, in what we spoke of as its waste; and that finally, when the animal ceased to exist, the constituents of its body were dissolved and transmitted to that inorganic world whence they had been at first abstracted. Thus we saw in both the blade of grass and the horse but the same elements differently combined and arranged. We discovered a continual circulation going on,--the plant drawing in the elements of inorganic nature and combining them into food for the animal creation; the animal borrowing from the plant the matter for its own support, giving off during its life products which returned immediately to the inorganic world; and that, eventually, the constituent materials of the whole structure of both animals and plants were thus returned to their original source: there was a constant passage from one state of existence to another, and a returning back again. Lastly, when we endeavoured to form some notion of the nature of the forces exercised by living beings, we discovered that they--if not capable of being subjected to the same minute analysis as the constituents of those beings themselves--that they were correlative with--that they were the equivalents of the forces of inorganic nature--that they were, in the sense in which the term is now used, convertible with them. That was our general result. And now, leaving the Present, I must endeavour in the same manner to put before you the facts that are to be discovered in the Past history of the living world, in the past conditions of organic nature. We have, to-night, to deal with the facts of that history--a history involving periods of time before which our mere human records sink into utter insignificance--a history the variety and physical magnitude of whose events cannot even be foreshadowed by the history of human life and human phenomena--a history of the most varied and complex character. We must deal with the history, then, in the first place, as we should deal with all other histories. The historical student knows that his first business should be to inquire into the validity of his evidence, and the nature of the record in which the evidence is contained, that he may be able to form a proper estimate of the correctness of the conclusions which have been drawn from that evidence. So, here we must pass, in the first place, to the consideration of a matter which may seem foreign to the question under discussion. We must dwell upon the nature of the records, and the credibility of the evidence they contain; we must look to the completeness or incompleteness of those records themselves, before we turn to that which they contain and reveal. The question of the credibility of the history, happily for us, will not require much consideration, for, in this history, unlike those of human origin, there can be no cavilling, no differences as to the reality and truth of the facts of which it is made up; the facts state themselves, and are laid out clearly before us. But, although one of the greatest difficulties of the historical student is cleared out of our path, there are other difficulties--difficulties in rightly interpreting the facts as they are presented to us--which may be compared with the greatest difficulties of any other kinds of historical study. What is this record of the past history of the globe, and what are the questions which are involved in an inquiry into its completeness or incompleteness? That record is composed of mud; and the question which we have to investigate this evening resolves itself into a question of the formation of mud. You may think, perhaps, that this is a vast step--of almost from the sublime to the ridiculous--from the contemplation of the history of the past ages of the world's existence to the consideration of the history of the formation of mud! But, in Nature, there is nothing mean and unworthy of attention; there is nothing ridiculous or contemptible in any of her works; and this inquiry, you will soon see, I hope, takes us to the very root and foundations of our subject. How, then, is mud formed? Always, with some trifling exceptions, which I need not consider now--always, as the result of the action of water, wearing down and disintegrating the surface of the earth and rocks with which it comes in contact--pounding and grinding it down, and carrying the particles away to places where they cease to be disturbed by this mechanical action, and where they can subside and rest. For the ocean, urged by winds, washes, as we know, a long extent of coast, and every wave, loaded as it is with particles of sand and gravel as it breaks upon the shore, does something towards the disintegrating process. And thus, slowly but surely, the hardest rocks are gradually ground down to a powdery substance; and the mud thus formed, coarser or finer, as the case may be, is carried by the rush of the tides, or currents, till it reaches the comparatively deeper parts of the ocean, in which it can sink to the bottom, that is, to parts where there is a depth of about fourteen or fifteen fathoms, a depth at which the water is, usually, nearly motionless, and in which, of course, the finer particles of this detritus, or mud as we call it, sinks to the bottom. Or, again, if you take a river, rushing down from its mountain sources, brawling over the stones and rocks that intersect its path, loosening, removing, and carrying with it in its downward course the pebbles and lighter matters from its banks, it crushes and pounds down the rocks and earths in precisely the same way as the wearing action of the sea waves. The matters forming the deposit are torn from the mountain-side and whirled impetuously into the valley, more slowly over the plain, thence into the estuary, and from the estuary they are swept into the sea. The coarser and heavier fragments are obviously deposited first, that is, as soon as the current begins to lose its force by becoming amalgamated with the stiller depths of the ocean, but the finer and lighter particles are carried further on, and eventually deposited in a deeper and stiller portion of the ocean. It clearly follows from this that mud gives us a chronology; for it is evident that supposing this, which I now sketch, to be the sea bottom, and supposing this to be a coast-line; from the washing action of the sea upon the rock, wearing and grinding it down into a sediment of mud, the mud will be carried down, and, at length, deposited in the deeper parts of this sea bottom, where it will form a layer; and then, while that first layer is hardening, other mud which is coming from the same source will, of course, be carried to the same place; and, as it is quite impossible for it to get beneath the layer already there, it deposits itself above it, and forms another layer, and in that way you gradually have layers of mud constantly forming and hardening one above the other, and conveying a record of time. It is a necessary result of the operation of the law of gravitation that the uppermost layer shall be the youngest and the lowest the oldest, and that the different beds shall be older at any particular point or spot in exactly the ratio of their depth from the surface. So that if they were upheaved afterwards, and you had a series of these different layers of mud, converted into sandstone, or limestone, as the case might be, you might be sure that the bottom layer was deposited first, and that the upper layers were formed afterwards. Here, you see, is the first step in the history--these layers of mud give us an idea of time. The whole surface of the earth,--I speak broadly, and leave out minor qualifications,--is made up of such layers of mud, so hard, the majority of them, that we call them rock whether limestone or sandstone, or other varieties of rock. And, seeing that every part of the crust of the earth is made up in this way, you might think that the determination of the chronology, the fixing of the time which it has taken to form this crust is a comparatively simple matter. Take a broad average, ascertain how fast the mud is deposited upon the bottom of the sea, or in the estuary of rivers; take it to be an inch, or two, or three inches a year, or whatever you may roughly estimate it at; then take the total thickness of the whole series of stratified rocks, which geologists estimate at twelve or thirteen miles, or about seventy thousand feet, make a sum in short division, divide the total thickness by that of the quantity deposited in one year, and the result will, of course, give you the number of years which the crust has taken to form. Truly, that looks a very simple process! It would be so except for certain difficulties, the very first of which is that of finding how rapidly sediments are deposited; but the main difficulty--a difficulty which renders any certain calculations of such a matter out of the question--is this, the sea-bottom on which the deposit takes place is continually shifting. Instead of the surface of the earth being that stable, fixed thing that it is popularly believed to be, being, in common parlance, the very emblem of fixity itself, it is incessantly moving, and is, in fact, as unstable as the surface of the sea, except that its undulations are infinitely slower and enormously higher and deeper. Now, what is the effect of this oscillation? Take the case to which I have previously referred. The finer or coarser sediments that are carried down by the current of the river, will only be carried out a certain distance, and eventually, as we have already seen, on reaching the stiller part of the ocean, will be deposited at the bottom. [Illustration: Fig. 4.] Let C _y_ (Fig. 4) be the sea-bottom, _y_ D the shore, _x y_ the sea-level, then the coarser deposit will subside over the region B, the finer over A, while beyond A there will be no deposit at all; and, consequently, no record will be kept, simply because no deposit is going on. Now, suppose that the whole land, C, D, which we have regarded as stationary, goes down, as it does so, both A and B go further out from the shore, which will be at _y1_; _x1_, _y1_, being the new sea-level. The consequence will be that the layer of mud (A), being now, for the most part, further than the force of the current is strong enough to convey even the finest _débris_, will, of course, receive no more deposits, and having attained a certain thickness will now grow no thicker. We should be misled in taking the thickness of that layer, whenever it may be exposed to our view, as a record of time in the manner in which we are now regarding this subject, as it would give us only an imperfect and partial record: it would seem to represent too short a period of time. Suppose, on the other hand, that the land (C D) had gone on rising slowly and gradually--say an inch or two inches in the course of a century,--what would be the practical effect of that movement? Why, that the sediment A and B which has been already deposited, would eventually be brought nearer to the shore-level and again subjected to the wear and tear of the sea; and directly the sea begins to act upon it, it would of course soon cut up and carry it way, to a greater or less extent, to be re-deposited further out. Well, as there is, in all probability, not one single spot on the whole surface of the earth, which has not been up and down in this way a great many times, it follows that the thickness of the deposits formed at any particular spot cannot be taken (even supposing we had at first obtained correct data as to the rate at which they took place), as affording reliable information as to the period of time occupied in its deposit. So that you see it is absolutely necessary from these facts, seeing that our record entirely consists of accumulations of mud, superimposed one on the other; seeing in the next place that any particular spots on which accumulations have occurred, have been constantly moving up and down, and sometimes out of the reach of a deposit, and at other times its own deposit broken up and carried away, it follows that our record must be in the highest degree imperfect, and we have hardly a trace left of thick deposits, or any definite knowledge of the area that they occupied, in a great many cases. And mark this! That supposing even that the whole surface of the earth had been accessible to the geologist,--that man had had access to every part of the earth, and had made sections of the whole, and put them all together,--even then his record must of necessity be imperfect. But to how much has man really access? If you will look at this map you will see that it represents the proportion of the sea to the earth: this coloured part indicates all the dry land, and this other portion is the water. You will notice at once that the water covers three-fifths of the whole surface of the globe, and has covered it in the same manner ever since man has kept any record of his own observations, to say nothing of the minute period during which he has cultivated geological inquiry. So that three-fifths of the surface of the earth is shut out from us because it is under the sea. Let us look at the other two-fifths, and see what are the countries in which anything that may be termed searching geological inquiry has been carried out: a good deal of France, Germany, and Great Britain and Ireland, bits of Spain, of Italy, and of Russia, have been examined, but of the whole great mass of Africa, except parts of the southern extremity, we know next to nothing; little bits of India, but of the greater part of the Asiatic continent nothing; bits of the Northern American States and of Canada, but of the greater part of the continent of North America, and in still larger proportion, of South America, nothing! Under these circumstances, it follows that even with reference to that kind of imperfect information which we can possess, it is only of about the ten-thousandth part of the accessible parts of the earth that has been examined properly. Therefore, it is with justice that the most thoughtful of those who are concerned in these inquiries insist continually upon the imperfection of the geological record; for, I repeat, it is absolutely necessary, from the nature of things, that that record should be of the most fragmentary and imperfect character. Unfortunately this circumstance has been constantly forgotten. Men of science, like young colts in a fresh pasture, are apt to be exhilarated on being turned into a new field of inquiry, to go off at a hand-gallop, in total disregard of hedges and ditches, to lose sight of the real limitation of their inquiries, and to forget the extreme imperfection of what is really known. Geologists have imagined that they could tell us what was going on at all parts of the earth's surface during a given epoch; they have talked of this deposit being contemporaneous with that deposit, until, from our little local histories of the changes at limited spots of the earth's surface, they have constructed a universal history of the globe as full of wonders and portents as any other story of antiquity. But what does this attempt to construct a universal history of the globe imply? It implies that we shall not only have a precise knowledge of the events which have occurred at any particular point, but that we shall be able to say what events, at any one spot, took place at the same time with those at other spots. Let us see how far that is in the nature of things practicable. Suppose that here I make a section of the Lake of Killarney, and here the section of another lake--that of Loch Lomond in Scotland for instance. The rivers that flow into them are constantly carrying down deposits of mud, and beds, or strata, are being as constantly formed, one above the other, at the bottom of those lakes. Now, there is not a shadow of doubt that in these two lakes the lower beds are all older than the upper--there is no doubt about that; but what does _this_ tell us about the age of any given bed in Loch Lomond, as compared with that of any given bed in the Lake of Killarney? It is, indeed, obvious that if any two sets of deposits are separated and discontinuous, there is absolutely no means whatever given you by the nature of the deposit of saying whether one is much younger or older than the other; but you may say, as many have said and think, that the case is very much altered if the beds which we are comparing are continuous. Suppose two beds of mud hardened into rock,--A and B--are seen in section. (Fig. 5.) [Illustration: Fig. 5.] Well, you say, it is admitted that the lowermost bed is always the older. Very well; B, therefore, is older than A. No doubt, _as a whole_, it is so; or if any parts of the two beds which are in the same vertical line are compared, it is so. But suppose you take what seems a very natural step further, and say that the part _a_ of the bed A is younger than the part _b_ of the bed B. Is this sound reasoning? If you find any record of changes taking place at _b_, did they occur before any events which took place while _a_ was being deposited? It looks all very plain sailing, indeed, to say that they did; and yet there is no proof of anything of the kind. As the former Director of this Institution, Sir H. De la Beche, long ago showed, this reasoning may involve an entire fallacy. It is extremely possible that _a_ may have been deposited ages before _b_. It is very easy to understand how that can be. To return to Fig. 4; when A and B were deposited, they were _substantially_ contemporaneous; A being simply the finer deposit, and B the coarser of the same detritus or waste of land. Now suppose that that sea-bottom goes down (as shown in Fig. 4), so that the first deposit is carried no farther than _a_, forming the bed A1, and the coarse no farther than _b_, forming the bed B1, the result will be the formation of two continuous beds, one of fine sediment (A A1) over-lapping another of coarse sediment (B B1). Now suppose the whole sea-bottom is raised up, and a section exposed about the point A1; no doubt, _at this spot_, the upper bed is younger than the lower. But we should obviously greatly err if we concluded that the mass of the upper bed at A was younger than the lower bed at B; for we have just seen that they are contemporaneous deposits. Still more should we be in error if we supposed the upper bed at A to be younger than the continuation of the lower bed at B1; for A was deposited long before B1. In fine, if, instead of comparing immediately adjacent parts of two beds, one of which lies upon another, we compare distant parts, it is quite possible that the upper may be any number of years older than the under, and the under any number of years younger than the upper. Now you must not suppose that I put this before you for the purpose of raising a paradoxical difficulty; the fact is, that the great mass of deposits have taken place in sea-bottoms which are gradually sinking, and have been formed under the very conditions I am here supposing. Do not run away with the notion that this subverts the principle I laid down at first. The error lies in extending a principle which is perfectly applicable to deposits in the same vertical line to deposits which are not in that relation to one another. It is in consequence of circumstances of this kind, and of others that I might mention to you, that our conclusions on and interpretations of the record are really and strictly only valid so long as we confine ourselves to one vertical section. I do not mean to tell you that there are no qualifying circumstances, so that, even in very considerable areas, we may safely speak of conformably superimposed beds being older or younger than others at many different points. But we can never be quite sure in coming to that conclusion, and especially we cannot be sure if there is any break in their continuity, or any very great distance between the points to be compared. Well now, so much for the record itself,--so much for its imperfections,--so much for the conditions to be observed in interpreting it, and its chronological indications, the moment we pass beyond the limits of a vertical linear section. Now let us pass from the record to that which it contains,--from the book itself to the writing and the figures on its pages. This writing and these figures consist of remains of animals and plants which, in the great majority of cases, have lived and died in the very spot in which we now find them, or at least in the immediate vicinity. You must all of you be aware--and I referred to the fact in my last lecture--that there are vast numbers of creatures living at the bottom of the sea. These creatures, like all others, sooner or later die, and their shells and hard parts lie at the bottom; and then the fine mud which is being constantly brought down by rivers and the action of the wear and tear of the sea, covers them over and protects them from any further change or alteration; and, of course, as in process of time the mud becomes hardened and solidified, the shells of these animals are preserved and firmly imbedded in the limestone or sandstone which is being thus formed. You may see in the galleries of the Museum up stairs specimens of limestones in which such fossil remains of existing animals are imbedded. There are some specimens in which turtles' eggs have been imbedded in calcareous sand, and before the sun had hatched the young turtles, they became covered over with calcareous mud, and thus have been preserved and fossilised. Not only does this process of imbedding and fossilisation occur with marine and other aquatic animals and plants, but it affects those land animals and plants which are drifted away to sea, or become buried in bogs or morasses; and the animals which have been trodden down by their fellows and crushed in the mud at the river's bank, as the herd have come to drink. In any of these cases, the organisms may be crushed or be mutilated, before or after putrefaction, in such a manner that perhaps only a part will be left in the form in which it reaches us. It is, indeed, a most remarkable fact, that it is quite an exceptional case to find a skeleton of any one of all the thousands of wild land animals that we know are constantly being killed, or dying in the course of nature: they are preyed on and devoured by other animals, or die in places where their bodies are not afterwards protected by mud. There are other animals existing on the sea, the shells of which form exceedingly large deposits. You are probably aware that before the attempt was made to lay the Atlantic telegraphic cable, the Government employed vessels in making a series of very careful observations and soundings of the bottom of the Atlantic; and although, as we must all regret, that up to the present time that project has not succeeded, we have the satisfaction of knowing that it yielded some most remarkable results to science. The Atlantic Ocean had to be sounded right across, to depths of several miles in some places, and the nature of its bottom was carefully ascertained. Well, now, a space of about 1,000 miles wide from east to west, and I do not exactly know how many from north to south, but at any rate 600 or 700 miles, was carefully examined, and it was found that over the whole of that immense area an excessively fine chalky mud is being deposited; and this deposit is entirely made up of animals whose hard parts are deposited in this part of the ocean, and are doubtless gradually acquiring solidity and becoming metamorphosed into a chalky limestone. Thus, you see, it is quite possible in this way to preserve unmistakable records of animal and vegetable life. Whenever the sea-bottom, by some of those undulations of the earth's crust that I have referred to, becomes up-heaved, and sections or borings are made, or pits are dug, then we become able to examine the contents and constituents of these ancient sea-bottoms, and find out what manner of animals lived at that period. Now it is a very important consideration in its bearing on the completeness of the record, to inquire how far the remains contained in these fossiliferous limestones are able to convey anything like an accurate or complete account of the animals which were in existence at the time of its formation. Upon that point we can form a very clear judgment, and one in which there is no possible room for any mistake. There are of course a great number of animals--such as jellyfishes, and other animals--without any hard parts, of which we cannot reasonably expect to find any traces whatever: there is nothing of them to preserve. Within a very short time, you will have noticed, after they are removed from the water, they dry up to a mere nothing; certainly they are not of a nature to leave any very visible traces of their existence on such bodies as chalk or mud. Then again, look at land animals; it is, as I have said, a very uncommon thing to find a land animal entire after death. Insects and other carnivorous animals very speedily pull them to pieces, putrefaction takes place, and so, out of the hundreds of thousands that are known to die every year, it is the rarest thing in the world to see one imbedded in such a way that its remains would be preserved for a lengthened period. Not only is this the case, but even when animal remains have been safely imbedded, certain natural agents may wholly destroy and remove them. Almost all the hard parts of animals--the bones and so on--are composed chiefly of phosphate of lime and carbonate of lime. Some years ago, I had to make an inquiry into the nature of some very curious fossils sent to me from the North of Scotland. Fossils are usually hard bony structures that have become imbedded in the way I have described, and have gradually acquired the nature and solidity of the body with which they are associated; but in this case I had a series of _holes_ in some pieces of rock, and nothing else. Those holes, however, had a certain definite shape about them, and when I got a skilful workman to make castings of the interior of these holes, I found that they were the impressions of the joints of a backbone and of the armour of a great reptile, twelve or more feet long. This great beast had died and got buried in the sand; the sand had gradually hardened over the bones, but remained porous. Water had trickled through it, and that water being probably charged with a superfluity of carbonic acid, had dissolved all the phosphate and carbonate of lime, and the bones themselves had thus decayed and entirely disappeared; but as the sandstone happened to have consolidated by that time, the precise shape of the bones was retained. If that sandstone had remained soft a little longer, we should have known nothing whatsoever of the existence of the reptile whose bones it had encased. How certain it is that a vast number of animals which have existed at one period on this earth have entirely perished, and left no trace whatever of their forms, may be proved to you by other considerations. There are large tracts of sandstone in various parts of the world, in which nobody has yet found anything but footsteps. Not a bone of any description, but an enormous number of traces of footsteps. There is no question about them. There is a whole valley in Connecticut covered with these footsteps, and not a single fragment of the animals which made them have yet been found. Let me mention another case while upon that matter, which is even more surprising than those to which I have yet referred. There is a limestone formation near Oxford, at a place called Stonesfield, which has yielded the remains of certain very interesting mammalian animals, and up to this time, if I recollect rightly, there have been found seven specimens of its lower jaws, and not a bit of anything else, neither limb-bones nor skull, nor any part whatever; not a fragment of the whole system! Of course, it would be preposterous to imagine that the beasts had nothing else but a lower jaw! The probability is, as Dr. Buckland showed, as the result of his observations on dead dogs in the river Thames, that the lower jaw, not being secured by very firm ligaments to the bones of the head, and being a weighty affair, would easily be knocked off, or might drop away from the body as it floated in water in a state of decomposition. The jaw would thus be deposited immediately, while the rest of the body would float and drift away altogether, ultimately reaching the sea, and perhaps becoming destroyed. The jaw becomes covered up and preserved in the river silt, and thus it comes that we have such a curious circumstance as that of the lower jaws in the Stonesfield slates. So that, you see, faulty as these layers of stone in the earth's crust are, defective as they necessarily are as a record, the account of contemporaneous vital phenomena presented by them is, by the necessity of the case, infinitely more defective and fragmentary. It was necessary that I should put all this very strongly before you, because, otherwise, you might have been led to think differently of the completeness of our knowledge by the next facts I shall state to you. The researches of the last three-quarters of a century have, in truth, revealed a wonderful richness of organic life in those rocks. Certainly not fewer than thirty or forty thousand different species of fossils have been discovered. You have no more ground for doubting that these creatures really lived and died at or near the places in which we find them than you have for like scepticism about a shell on the sea-shore. The evidence is as good in the one case as in the other. Our next business is to look at the general character of these fossil remains, and it is a subject which will be requisite to consider carefully; and the first point for us is to examine how much the extinct _Flora_ and _Fauna_ as a _whole_--disregarding altogether the _succession_ of their constituents, of which I shall speak afterwards--differ from the _Flora_ and _Fauna_ of the present day;--how far they differ in what we _do_ know about them, leaving altogether out of consideration speculations based upon what we _do not_ know. I strongly imagine that if it were not for the peculiar appearance that fossilised animals have, any of you might readily walk through a museum which contains fossil remains mixed up with those of the present forms of life, and I doubt very much whether your uninstructed eyes would lead you to see any vast or wonderful difference between the two. If you looked closely, you would notice, in the first place, a great many things very like animals with which you are acquainted now: you would see differences of shape and proportion, but on the whole a close similarity. I explained what I meant by ORDERS the other day, when I described the animal kingdom as being divided into sub-kingdoms, classes and orders. If you divide the animal kingdom into orders you will find that there are above one hundred and twenty. The number may vary on one side or the other, but this is a fair estimate. That is the sum total of the orders of all the animals which we know now, and which have been known in past times, and left remains behind. Now, how many of those are absolutely extinct? That is to say, how many of these orders of animals have lived at a former period of the world's history but have at present no representatives? That is the sense in which I meant to use the word "extinct." I mean that those animals did live on this earth at one time, but have left no one of their kind with us at the present moment. So that estimating the number of extinct animals is a sort of way of comparing the past creation as a whole with the present as a whole. Among the mammalia and birds there are none extinct; but when we come to the reptiles there is a most wonderful thing: out of the eight orders, or thereabouts, which you can make among reptiles, one-half are extinct. These diagrams of the plesiosaurus, the ichthyosaurus, the pterodactyle, give you a notion of some of these extinct reptiles. And here is a cast of the pterodactyle and bones of the ichthyosaurus and the plesiosaurus, just as fresh-looking as if it had been recently dug up in a churchyard. Thus, in the reptile class, there are no less than half of the orders which are absolutely extinct. If we turn to the _Amphibia_, there was one extinct order, the Labyrinthodonts, typified by the large salamander-like beast shown in this diagram. No order of fishes is known to be extinct. Every fish that we find in the strata--to which I have been referring--can be identified and placed in one of the orders which exist at the present day. There is not known to be a single ordinal form of insect extinct. There are only two orders extinct among the _Crustacea_. There is not known to be an extinct order of these creatures, the parasitic and other worms; but there are two, not to say three, absolutely extinct orders of this class, the _Echinodermata_; out of all the orders of the _Coelenterata_ and _Protozoa_ only one, the Rugose Corals. So that, you see, out of somewhere about 120 orders of animals, taking them altogether, you will not, at the outside estimate, find above ten or a dozen extinct. Summing up all the order of animals which have left remains behind them, you will not find above ten or a dozen which cannot be arranged with those of the present day; that is to say, that the difference does not amount to much more than ten per cent.: and the proportion of extinct orders of plants is still smaller. I think that that is a very astounding a most astonishing fact: seeing the enormous epochs of time which have elapsed during the constitution of the surface of the earth as it at present exists, it is, indeed, a most astounding thing that the proportion of extinct ordinal types should be so exceedingly small. But now, there is another point of view in which we must look at this past creation. Suppose that we were to sink a vertical pit through the floor beneath us, and that I could succeed in making a section right through in the direction of New Zealand, I should find in each of the different beds through which I passed the remains of animals which I should find in that stratum and not in the others. First, I should come upon beds of gravel or drift containing the bones of large animals, such as the elephant, rhinoceros, and cave tiger. Rather curious things to fall across in Piccadilly! If I should dig lower still, I should come upon a bed of what we call the London clay, and in this, as you will see in our galleries up stairs, are found remains of strange cattle, remains of turtles, palms, and large tropical fruits; with shell-fish such as you see the like of now only in tropical regions. If I went below that, I should come upon the chalk, and there I should find something altogether different, the remains of ichthyosauria and pterodactyles, and ammonites, and so forth. I do not know what Mr. Godwin Austin would say comes next, but probably rocks containing more ammonites, and more ichthyosauria and plesiosauria, with a vast number of other things; and under that I should meet with yet older rocks containing numbers of strange shells and fishes; and in thus passing from the surface to the lowest depths of the earth's crust, the forms of animal life and vegetable life which I should meet with in the successive beds would, looking at them broadly, be the more different the further that I went down. Or, in other words, inasmuch as we started with the clear principle, that in a series of naturally-disposed mud beds the lowest are the oldest, we should come to this result, that the further we go back in time the more difference exists between the animal and vegetable life of an epoch and that which now exists. That was the conclusion to which I wished to bring you at the end of this lecture. III. THE METHOD BY WHICH THE CAUSES OF THE PRESENT AND PAST CONDITIONS OF ORGANIC NATURE ARE TO BE DISCOVERED;--THE ORIGINATION OF LIVING BEINGS In the two preceding lectures I have endeavoured to indicate to you the extent of the subject-matter of the inquiry upon which we are engaged; and having thus acquired some conception of the past and present phenomena of organic nature, I must now turn to that which constitutes the great problem which we have set before ourselves;--I mean, the question of what knowledge we have of the causes of these phenomena of organic nature, and how such knowledge is obtainable. Here, on the threshold of the inquiry, an objection meets us. There are in the world a number of extremely worthy, well-meaning persons, whose judgments and opinions are entitled to the utmost respect on account of their sincerity, who are of opinion that vital phenomena, and especially all questions relating to the origin of vital phenomena, are questions quite apart from the ordinary run of inquiry, and are, by their very nature, placed out of our reach. They say that all these phenomena originated miraculously, or in some way totally different from the ordinary course of nature, and that therefore they conceive it to be futile, not to say presumptuous, to attempt to inquire into them. To such sincere and earnest persons, I would only say, that a question of this kind is not to be shelved upon theoretical or speculative grounds. You may remember the story of the Sophist who demonstrated to Diogenes in the most complete and satisfactory manner that he could not walk; that, in fact, all motion was an impossibility; and that Diogenes refuted him by simply getting up and walking round his tub. So, in the same way, the man of science replies to objections of this kind, by simply getting up and walking onward, and showing what science has done and is doing---by pointing to that immense mass of facts which have been ascertained as systematised under the forms of the great doctrines of morphology, of development, of distribution, and the like. He sees an enormous mass of facts and laws relating to organic beings, which stand on the same good sound foundation as every other natural law. With this mass of facts and laws before us, therefore, seeing that, as far as organic matters have hitherto been accessible and studied, they have shown themselves capable of yielding to scientific investigation, we may accept this as proof that order and law reign there as well as in the rest of Nature. The man of science says nothing to objectors of this sort, but supposes that we can and shall walk to a knowledge of the origin of organic nature, in the same way that we have walked to a knowledge of the laws and principles of the inorganic world. But there are objectors who say the same from ignorance and ill-will. To such I would reply that the objection comes ill from them, and that the real presumption, I may almost say the real blasphemy, in this matter, is in the attempt to limit that inquiry into the causes of phenomena, which is the source of all human blessings, and from which has sprung all human prosperity and progress; for, after all, we can accomplish comparatively little; the limited range of our own faculties bounds us on every side,--the field of our powers of observation is small enough, and he who endeavours to narrow the sphere of our inquiries is only pursuing a course that is likely to produce the greatest harm to his fellow-men. But now, assuming, as we all do, I hope, that these phenomena are properly accessible to inquiry, and setting out upon our search into the causes of the phenomena of organic nature, or at any rate, setting out to discover how much we at present know upon these abstruse matters, the question arises as to what is to be our course of proceeding, and what method we must lay down for our guidance. I reply to that question, that our method must be exactly the same as that which is pursued in any other scientific inquiry, the method of scientific investigation being the same for all orders of facts and phenomena whatsoever. I must dwell a little on this point, for I wish you to leave this room with a very clear conviction that scientific investigation is not, as many people seem to suppose, some kind of modern black art. I say that you might easily gather this impression from the manner in which many persons speak of scientific inquiry, or talk about inductive and deductive philosophy, or the principles of the "Baconian philosophy." I do protest that, of the vast number of cants in this world, there are none, to my mind, so contemptible as the pseudo-scientific cant which is talked about the "Baconian philosophy." To hear people talk about the great Chancellor--and a very great man he certainly was,--you would think that it was he who had invented science, and that there was no such thing as sound reasoning before the time of Queen Elizabeth! Of course you say, that cannot possibly be true; you perceive, on a moment's reflection, that such an idea is absurdly wrong, and yet, so firmly rooted is this sort of impression,--I cannot call it an idea, or conception,--the thing is too absurd to be entertained,--but so completely does it exist at the bottom of most men's minds, that this has been a matter of observation with me for many years past. There are many men who, though knowing absolutely nothing of the subject with which they may be dealing, wish, nevertheless, to damage the author of some view with which they think fit to disagree. What they do, then, is not to go and learn something about the subject, which one would naturally think the best way of fairly dealing with it; but they abuse the originator of the view they question, in a general manner, and wind up by saying that, "After all, you know, the principles and method of this author are totally opposed to the canons of the Baconian philosophy." Then everybody applauds, as a matter of course, and agrees that it must be so. But if you were to stop them all in the middle of their applause, you would probably find that neither the speaker nor his applauders could tell you how or in what way it was so; neither the one nor the other having the slightest idea of what they mean when they speak of the "Baconian philosophy." You will understand, I hope, that I have not the slightest desire to join in the outcry against either the morals, the intellect, or the great genius of Lord Chancellor Bacon. He was undoubtedly a very great man, let people say what they will of him; but notwithstanding all that he did for philosophy, it would be entirely wrong to suppose that the methods of modern scientific inquiry originated with him, or with his age; they originated with the first man, whoever he was; and indeed existed long before him, for many of the essential processes of reasoning are exerted by the higher order of brutes as completely and effectively as by ourselves. We see in many of the brute creation the exercise of one, at least, of the same powers of reasoning as that which we ourselves employ. The method of scientific investigation is nothing but the expression of the necessary mode of working of the human mind. It is simply the mode at which all phenomena are reasoned about, rendered precise and exact. There is no more difference, but there is just the same kind of difference, between the mental operations of a man of science and those of an ordinary person, as there is between the operations and methods of a baker or of a butcher weighing out his goods in common scales, and the operations of a chemist in performing a difficult and complex analysis by means of his balance and finely-graduated weights. It is not that the action of the scales in the one case, and the balance in the other, differ in the principles of their construction or manner of working; but the beam of one is set on an infinitely finer axis than the other, and of course turns by the addition of a much smaller weight. You will understand this better, perhaps, if I give you some familiar example. You have all heard it repeated, I dare say, that men of science work by means of induction and deduction, and that by the help of these operations, they, in a sort of sense, wring from Nature certain other things, which are called natural laws, and causes, and that out of these, by some cunning skill of their own, they build up hypotheses and theories. And it is imagined by many, that the operations of the common mind can be by no means compared with these processes, and that they have to be acquired by a sort of special apprenticeship to the craft. To hear all these large words, you would think that the mind of a man of science must be constituted differently from that of his fellow men; but if you will not be frightened by terms, you will discover that you are quite wrong, and that all these terrible apparatus are being used by yourselves every day and every hour of your lives. There is a well-known incident in one of Molière's plays, where the author makes the hero express unbounded delight on being told that he had been talking prose during the whole of his life. In the same way, I trust, that you will take comfort, and be delighted with yourselves, on the discovery that you have been acting on the principles of inductive and deductive philosophy during the same period. Probably there is not one here who has not in the course of the day had occasion to set in motion a complex train of reasoning, of the very same kind, though differing of course in degree, as that which a scientific man goes through in tracing the causes of natural phenomena. A very trivial circumstance will serve to exemplify this. Suppose you go into a fruiterer's shop, wanting an apple,--you take up one, and, on biting it, you find it is sour; you look at it, and see that it is hard and green. You take up another one, and that too is hard, green, and sour. The shopman offers you a third; but, before biting it, you examine it, and find that it is hard and green, and you immediately say that you will not have it, as it must be sour, like those that you have already tried. Nothing can be more simple than that, you think; but if you will take the trouble to analyse and trace out into its logical elements what has been done by the mind, you will be greatly surprised. In the first place, you have performed the operation of induction. You found that, in two experiences, hardness and greenness in apples went together with sourness. It was so in the first case, and it was confirmed by the second. True, it is a very small basis, but still it is enough to make an induction from; you generalise the facts, and you expect to find sourness in apples where you get hardness and greenness. You found upon that a general law, that all hard and green apples are sour; and that, so far as it goes, is a perfect induction. Well, having got your natural law in this way, when you are offered another apple which you find is hard and green, you say, "All hard and green apples are sour; this apple is hard and green, therefore this apple is sour." That train of reasoning is what logicians call a syllogism, and has all its various parts and terms,--its major premiss, its minor premiss, and its conclusion. And, by the help of further reasoning, which, if drawn out, would have to be exhibited in two or three other syllogisms, you arrive at your final determination, "I will not have that apple." So that, you see, you have, in the first place, established a law by induction, and upon that you have founded a deduction, and reasoned out the special conclusion of the particular case. Well now, suppose, having got your law, that at some time afterwards, you are discussing the qualities of apples with a friend: you will say to him, "It is a very curious thing,--but I find that all hard and green apples are sour!" Your friend says to you, "But how do you know that?" You at once reply, "Oh, because I have tried them over and over again, and have always found them to be so." Well, if we were talking science instead of common sense, we should call that an experimental verification. And, if still opposed, you go further, and say, "I have heard from the people in Somersetshire and Devonshire, where a large number of apples are grown, that they have observed the same thing. It is also found to be the case in Normandy, and in North America. In short, I find it to be the universal experience of mankind wherever attention has been directed to the subject." Whereupon, your friend, unless he is a very unreasonable man, agrees with you, and is convinced that you are quite right in the conclusion you have drawn. He believes, although perhaps he does not know he believes it, that the more extensive verifications are,--that the more frequently experiments have been made, and results of the same kind arrived at,--that the more varied the conditions under which the same results are attained, the more certain is the ultimate conclusion, and he disputes the question no further. He sees that the experiment has been tried under all sorts of conditions, as to time, place, and people, with the same result; and he says with you, therefore, that the law you have laid down must be a good one, and he must believe it. In science we do the same thing;--the philosopher exercises precisely the same faculties, though in a much more delicate manner. In scientific inquiry it becomes a matter of duty to expose a supposed law to every possible kind of verification, and to take care, moreover, that this is done intentionally, and not left to a mere accident, as in the case of the apples. And in science, as in common life, our confidence in a law is in exact proportion to the absence, of variation in the result of our experimental verifications. For instance, if you let go your grasp of an article you may have in your hand, it will immediately fall to the ground. That is a very common verification of one of the best established laws of nature--that of gravitation. The method by which men of science establish the existence of that law is exactly the same as that by which we have established the trivial proposition about the sourness of hard and green apples. But we believe it in such an extensive, thorough, and unhesitating manner because the universal experience of mankind verifies it, and we can verify it ourselves at any time; and that is the strongest possible foundation on which any natural law can rest. So much, then, by way of proof that the method of establishing laws in science is exactly the same as that pursued in common life. Let us now turn to another matter (though really it is but another phase of the same question), and that is, the method by which, from the relations of certain phenomena, we prove that some stand in the position of causes towards the others. I want to put the case clearly before you, and I will therefore show you what I mean by another familiar example. I will suppose that one of you, on coming down in the morning to the parlour of your house, finds that a tea-pot and some spoons which had been left in the room on the previous evening are gone,--the window is open, and you observe the mark of a dirty hand on the window-frame, and perhaps, in addition to that, you notice the impress of a hob-nailed shoe on the gravel outside. All these phenomena have struck your attention instantly, and before two seconds have passed you say, "Oh, somebody has broken open the window, entered the room, and run off with the spoons and the tea-pot!" That speech is out of your mouth in a moment. And you will probably add, "I know there has; I am quite sure of it!" You mean to say exactly what you know; but in reality you are giving expression to what is, in all essential particulars, an hypothesis. You do not _know_ it at all; it is nothing but an hypothesis rapidly framed in your own mind. And it is an hypothesis founded on a long train of inductions and deductions. What are those inductions and deductions, and how have you got at this hypothesis? You have observed, in the first place, that the window is open; but by a train of reasoning involving many inductions and deductions, you have probably arrived long before at the general law--and a very good one it is--that windows do not open of themselves; and you therefore conclude that something has opened the window. A second general law that you have arrived at in the same way is, that tea-pots and spoons do not go out of a window spontaneously, and you are satisfied that, as they are not now where you left them, they have been removed. In the third place, you look at the marks on the window-sill, and the shoe-marks outside, and you say that in all previous experience the former kind of mark has never been produced by anything else but the hand of a human being; and the same experience shows that no other animal but man at present wears shoes with hob-nails in them such as would produce the marks in the gravel. I do not know, even if we could discover any of those "missing links" that are talked about, that they would help us to any other conclusion! At any rate the law which states our present experience is strong enough for my present purpose. You next reach the conclusion, that as these kinds of marks have not been left by any other animals than men, or are liable to be formed in any other way than by a man's hand and shoe, the marks in question have been formed by a man in that way. You have, further, a general law, founded on observation and experience, and that, too, is, I am sorry to say, a very universal and unimpeachable one,--that some men are thieves; and you assume at once from all these premisses--and that is what constitutes your hypothesis--that the man who made the marks outside and on the window-sill, opened the window, got into the room, and stole your tea-pot and spoons. You have now arrived at a _vera causa_;--you have assumed a cause which, it is plain, is competent to produce all the phenomena you have observed. You can explain all these phenomena only by the hypothesis of a thief. But that is a hypothetical conclusion, of the justice of which you have no absolute proof at all; it is only rendered highly probable by a series of inductive and deductive reasonings. I suppose your first action, assuming that you are a man of ordinary common sense, and that you have established this hypothesis to your own satisfaction, will very likely be to go off for the police, and set them on the track of the burglar, with the view to the recovery of your property. But just as you are starting with this object, some person comes in, and on learning what you are about, says, "My good friend, you are going on a great deal too fast. How do you know that the man who really made the marks took the spoons? It might have been a monkey that took them, and the man may have merely looked in afterwards." You would probably reply, "Well, that is all very well, but you see it is contrary to all experience of the way tea-pots and spoons are abstracted; so that, at any rate, your hypothesis is less probable than mine." While you are talking the thing over in this way, another friend arrives, one of that good kind of people that I was talking of a little while ago. And he might say, "Oh, my dear sir, you are certainly going on a great deal too fast. You are most presumptuous. You admit that all these occurrences took place when you were fast asleep, at a time when you could not possibly have known anything about what was taking place. How do you know that the laws of Nature are not suspended during the night? It may be that there has been some kind of supernatural interference in this case." In point of fact, he declares that your hypothesis is one of which you cannot at all demonstrate the truth, and that you are by no means sure that the laws of Nature are the same when you are asleep as when you are awake. Well, now, you cannot at the moment answer that kind of reasoning. You feel that your worthy friend has you somewhat at a disadvantage. You will feel perfectly convinced in your own mind, however, that you are quite right, and you say to him, "My good friend, I can only be guided by the natural probabilities of the case, and if you will be kind enough to stand aside and permit me to pass, I will go and fetch the police." Well, we will suppose that your journey is successful, and that by good luck you meet with a policeman; that eventually the burglar is found with your property on his person, and the marks correspond to his hand and to his boots. Probably any jury would consider those facts a very good experimental verification of your hypothesis, touching the cause of the abnormal phenomena observed in your parlour, and would act accordingly. Now, in this suppositious case, I have taken phenomena of a very common kind, in order that you might see what are the different steps in an ordinary process of reasoning, if you will only take the trouble to analyse it carefully. All the operations I have described, you will see, are involved in the mind of any man of sense in leading him to a conclusion as to the course he should take in order to make good a robbery and punish the offender. I say that you are led, in that case, to your conclusion by exactly the same train of reasoning as that which a man of science pursues when he is endeavouring to discover the origin and laws of the most occult phenomena. The process is, and always must be, the same; and precisely the same mode of reasoning was employed by Newton and Laplace in their endeavours to discover and define the causes of the movements of the heavenly bodies, as you, with your own common sense, would employ to detect a burglar. The only difference is, that the nature of the inquiry being more abstruse, every step has to be most carefully watched, so that there may not be a single crack or flaw in your hypothesis. A flaw or crack in many of the hypotheses of daily life may be of little or no moment as affecting the general correctness of the conclusions at which we may arrive; but, in a scientific inquiry, a fallacy, great or small, is always of importance, and is sure to be in the long run constantly productive of mischievous, if not fatal results. Do not allow yourselves to be misled by the common notion that an hypothesis is untrustworthy simply because it is an hypothesis. It is often urged, in respect to some scientific conclusion, that, after all, it is only an hypothesis. But what more have we to guide us in nine-tenths of the most important affairs of daily life than hypotheses, and often very ill-based ones? So that in science, where the evidence of an hypothesis is subjected to the most rigid examination, we may rightly pursue the same course. You may have hypotheses and hypotheses. A man may say, if he likes, that the moon is made of green cheese: that is an hypothesis. But another man, who has devoted a great deal of time and attention to the subject, and availed himself of the most powerful telescopes and the results of the observations of others, declares that in his opinion it is probably composed of materials very similar to those of which our own earth is made up: and that is also only an hypothesis. But I need not tell you that there is an enormous difference in the value of the two hypotheses. That one which is based on sound scientific knowledge is sure to have a corresponding value; and that which is a mere hasty random guess is likely to have but little value. Every great step in our progress in discovering causes has been made in exactly the same way as that which I have detailed to you. A person observing the occurrence of certain facts and phenomena asks, naturally enough, what process, what kind of operation known to occur in Nature applied to the particular case, will unravel and explain the mystery? Hence you have the scientific hypothesis; and its value will be proportionate to the care and completeness with which its basis had been tested and verified. It is in these matters as in the commonest affairs of practical life: the guess of the fool will be folly, while the guess of the wise man will contain wisdom. In all cases, you see that the value of the result depends on the patience and faithfulness with which the investigator applies to his hypothesis every possible kind of verification. I dare say I may have to return to this point by and by; but having dealt thus far with our logical methods, I must now turn to something which, perhaps, you may consider more interesting, or, at any rate, more tangible. But in reality there are but few things that can be more important for you to understand than the mental processes and the means by which we obtain scientific conclusions and theories. [Footnote: Those who wish to study fully the doctrines of which I have endeavoured to give some rough-and-ready illustrations, must read Mr. John Stuart Mill's _System of Logic_.] Having granted that the inquiry is a proper one, and having determined on the nature of the methods we are to pursue and which only can lead to success, I must now turn to the consideration of our knowledge of the nature of the processes which have resulted in the present condition of organic nature. Here, let me say at once, lest some of you misunderstand me, that I have extremely little to report. The question of how the present condition of organic nature came about, resolves itself into two questions. The first is: How has organic or living matter commenced its existence? And the second is: How has it been perpetuated? On the second question I shall have more to say hereafter. But on the first one, what I now have to say will be for the most part of a negative character. If you consider what kind of evidence we can have upon this matter, it will resolve itself into two kinds. We may have historical evidence and we may have experimental evidence. It is, for example, conceivable, that inasmuch as the hardened mud which forms a considerable portion of the thickness of the earth's crust contains faithful records of the past forms of life, and inasmuch as these differ more and more as we go further down,--it is possible and conceivable that we might come to some particular bed or stratum which should contain the remains of those creatures with which organic life began upon the earth. And if we did so, and if such forms of organic life were preservable, we should have what I would call historical evidence of the mode in which organic life began upon this planet. Many persons will tell you, and indeed you will find it stated in many works on geology, that this has been done, and that we really possess such a record; there are some who imagine that the earliest forms of life of which we have as yet discovered any record, are in truth the forms in which animal life began upon the globe. The grounds on which they base that supposition are these:--That if you go through the enormous thickness of the earth's crust and get down to the older rocks, the higher vertebrate animals--the quadrupeds, birds, and fishes--cease to be found; beneath them you find only the invertebrate animals; and in the deepest and lowest rocks those remains become scantier and scantier, not in any very gradual progression, however, until, at length, in what are supposed to be the oldest rocks, the animal remains which are found are almost always confined to four forms--_Oldhamia_, whose precise nature is not known, whether plant or animal; _Lingula_, a kind of mollusc; _Trilobites_, a crustacean animal, having the same essential plan of construction, though differing in many details from a lobster or crab; and _Hymenocaris_, which is also a crustacean. So that you have all the _Fauna_ reduced, at this period, to four forms: one a kind of animal or plant that we know nothing about, and three undoubted animals--two crustaceans and one mollusc. I think, considering the organisation of these mollusca and crustacea, and looking at their very complex nature, that it does indeed require a very strong imagination to conceive that these were the first created of all living things. And you must take into consideration the fact that we have not the slightest proof that these which we call the oldest beds are really so: I repeat, we have not the slightest proof of it. When you find in some places that in an enormous thickness of rocks there are but very scanty traces of life, or absolutely none at all; and that in other parts of the world rocks of the very same formation are crowded with the records of living forms, I think it is impossible to place any reliance on the supposition, or to feel one's self justified in supposing that these are the forms in which life first commenced. I have not time here to enter upon the technical grounds upon which I am led to this conclusion,--that could hardly be done properly in half a dozen lectures on that part alone:--I must content myself with saying that I do not at all believe that these are the oldest forms of life. I turn to the experimental side to see what evidence we have there. To enable us to say that we know anything about the experimental origination of organisation and life, the investigator ought to be able to take inorganic matters, such as carbonic acid, ammonia, water, and salines, in any sort of inorganic combination, and be able to build them up into protein matter, and then that protein matter ought to begin to live in an organic form. That, nobody has done as yet, and I suspect it will be a long while before anybody does do it. But the thing is by no means so impossible as it looks; for the researches of modern chemistry have shown us--I won't say the road towards it, but, if I may so say, they have shown the finger-post pointing to the road that may lead to it. It is not many years ago--and you must recollect that Organic Chemistry is a young science, not above a couple of generations old, you must not expect too much of it,--it is not many years ago since it was said to be perfectly impossible to fabricate any organic compound; that is to say, any non-mineral compound which is to be found in an organised being. It remained so for a very long period; but it is now a considerable number of years since a distinguished foreign chemist contrived to fabricate urea, a substance of a very complex character, which forms one of the waste products of animal structures. And of late years a number of other compounds, such as butyric acid, and others, have been added to the list. I need not tell you that chemistry is an enormous distance from the goal I indicate; all I wish to point out to you is, that it is by no means safe to say that that goal may not be reached one day. It may be that it is impossible for us to produce the conditions requisite to the origination of life; but we must speak modestly about the matter, and recollect that Science has put her foot upon the bottom round of the ladder. Truly he would be a bold man who would venture to predict where she will be fifty years hence. There is another inquiry which bears indirectly upon this question, and upon which I must say a few words. You are all of you aware of the phenomena of what is called spontaneous generation. Our forefathers, down to the seventeenth century, or thereabouts, all imagined, in perfectly good faith, that certain vegetable and animal forms gave birth, in the process of their decomposition, to insect life. Thus, if you put a piece of meat in the sun, and allowed it to putrefy, they conceived that the grubs which soon began to appear were the result of the action of a power of spontaneous generation which the meat contained. And they could give you receipts for making various animal and vegetable preparations which would produce particular kinds of animals. A very distinguished Italian naturalist, named Redi, took up the question, at a time when everybody believed in it; among others our own great Harvey, the discoverer of the circulation of the blood. You will constantly find his name quoted, however, as an opponent of the doctrine of spontaneous generation; but the fact is, and you will see it if you will take the trouble to look into his works, Harvey believed it as profoundly as any man of his time; but he happened to enunciate a very curious proposition--that every living thing came from an _egg_; he did not mean to use the word in the sense in which we now employ it, he only meant to say that every living thing originated in a little rounded particle of organised substance; and it is from this circumstance, probably, that the notion of Harvey having opposed the doctrine originated. Then came Redi, and he proceeded to upset the doctrine in a very simple manner. He merely covered the piece of meat with some very fine gauze, and then he exposed it to the same conditions. The result of this was that no grubs or insects were produced; he proved that the grubs originated from the insects who came and deposited their eggs in the meat, and that they were hatched by the heat of the sun. By this kind of inquiry he thoroughly upset the doctrine of spontaneous generation, for his time at least. Then came the discovery and application of the microscope to scientific inquiries, which showed to naturalists that besides the organisms which they already knew as living beings and plants, there were an immense number of minute things which could be obtained apparently almost at will from decaying vegetable and animal forms. Thus, if you took some ordinary black pepper or some hay, and steeped it in water, you would find in the course of a few days that the water had become impregnated with an immense number of animalcules swimming about in all directions. From facts of this kind naturalists were led to revive the theory of spontaneous generation. They were headed here by an English naturalist,--Needham,--and afterwards in France by the learned Buffon. They said that these things were absolutely begotten in the water of the decaying substances out of which the infusion was made. It did not matter whether you took animal or vegetable matter, you had only to steep it in water and expose it, and you would soon have plenty of animalcules. They made an hypothesis about this which was a very fair one. They said, this matter of the animal world, or of the higher plants, appears to be dead, but in reality it has a sort of dim life about it, which, if it is placed under fair conditions, will cause it to break up into the forms of these little animalcules, and they will go through their lives in the same way as the animal or plant of which they once formed a part. The question now became very hotly debated. Spallanzani, an Italian naturalist, took up opposite views to those of Needham and Buffon, and by means of certain experiments he showed that it was quite possible to stop the process by boiling the water, and closing the vessel in which it was contained. "Oh!" said his opponents; "but what do you know you may be doing when you heat the air over the water in this way? You may be destroying some property of the air requisite for the spontaneous generation of the animalcules." However, Spallanzani's views were supposed to be upon the right side, and those of the others fell into discredit; although the fact was that Spallanzani had not made good his views. Well, then, the subject continued to be revived from time to time, and experiments were made by several persons; but these experiments were not altogether satisfactory. It was found that if you put an infusion in which animalcules would appear if it were exposed to the air into a vessel and boiled it, and then sealed up the mouth of the vessel, so that no air, save such as had been heated to 212°, could reach its contents, that then no animalcules would be found; but if you took the same vessel and exposed the infusion to the air, then you would get animalcules. Furthermore, it was found that if you connected the mouth of the vessel with a red-hot tube in such a way that the air would have to pass through the tube before reaching the infusion, that then you would get no animalcules. Yet another thing was noticed: if you took two flasks containing the same kind of infusion, and left one entirely exposed to the air, and in the mouth of the other placed a ball of cotton wool, so that the air would have to filter itself through it before reaching the infusion, that then, although you might have plenty of animalcules in the first flask, you would certainly obtain none from the second. These experiments, you see, all tended towards one conclusion--that the infusoria were developed from little minute spores or eggs which were constantly floating in the atmosphere, and which lose their power of germination if subjected to heat. But one observer now made another experiment, which seemed to go entirely the other way, and puzzled him altogether. He took some of this boiled infusion that I have been speaking of, and by the use of a mercurial bath--a kind of trough used in laboratories--he deftly inverted a vessel containing the infusion into the mercury, so that the latter reached a little beyond the level of the mouth of the _inverted_ vessel. You see that he thus had a quantity of the infusion shut off from any possible communication with the outer air by being inverted upon a bed of mercury. He then prepared some pure oxygen and nitrogen gases, and passed them by means of a tube going from the outside of the vessel, up through the mercury into the infusion; so that he thus had it exposed to a perfectly pure atmosphere of the same constituents as the external air. Of course, he expected he would get no infusorial animalcules at all in that infusion; but, to his great dismay and discomfiture, he found he almost always did get them. Furthermore, it has been found that experiments made in the manner described above answer well with most infusions; but that if you fill the vessel with boiled milk, and then stop the neck with cotton-wool, you _will_ have infusoria. So that you see there were two experiments that brought you to one kind of conclusion, and three to another; which was a most unsatisfactory state of things to arrive at in a scientific inquiry. Some few years after this, the question began to be very hotly discussed in France. There was M. Pouchet, a professor at Rouen, a very learned man, but certainly not a very rigid experimentalist. He published a number of experiments of his own, some of which were very ingenious, to show that if you went to work in a proper way, there was a truth in the doctrine of spontaneous generation. Well, it was one of the most fortunate things in the world that M. Pouchet took up this question, because it induced a distinguished French chemist, M. Pasteur, to take up the question on the other side; and he has certainly worked it out in the most perfect manner. I am glad to say, too, that he has published his researches in time to enable me to give you an account of them. He verified all the experiments which I have just mentioned to you--and then finding those extraordinary anomalies, as in the case of the mercury bath and the milk, he set himself to work to discover their nature. In the case of milk he found it to be a question of temperature. Milk in a fresh state is slightly alkaline; and it is a very curious circumstance, but this very slight degree of alkalinity seems to have the effect of preserving the organisms which fall into it from the air from being destroyed at a temperature of 212°, which is the boiling point. But if you raise the temperature 10° when you boil it, the milk behaves like everything else; and if the air with which it comes in contact, after being boiled at this temperature, is passed through a red-hot tube, you will not get a trace of organisms. He then turned his attention to the mercury bath, and found on examination that the surface of the mercury was almost always covered with a very fine dust. He found that even the mercury itself was positively full of organic matters; that from being constantly exposed to the air, it had collected an immense number of these infusorial organisms from the air. Well, under these circumstances he felt that the case was quite clear, and that the mercury was not what it had appeared to M. Schwann to be,--a bar to the admission of these organisms; but that, in reality, it acted as a reservoir from which the infusion was immediately supplied with the large quantity that had so puzzled him. But not content with explaining the experiments of others, M. Pasteur went to work to satisfy himself completely. He said to himself: "If my view is right, and if, in point of fact, all these appearances of spontaneous generation are altogether due to the falling of minute germs suspended in the atmosphere,--why, I ought not only to be able to show the germs, but I ought to be able to catch and sow them, and produce the resulting organisms." He, accordingly, constructed a very ingenious apparatus to enable him to accomplish the trapping of the "_germ dust_" in the air. He fixed in the window of his room a glass tube, in the centre of which he had placed a ball of gun-cotton, which, as you all know, is ordinary cotton-wool, which, from having been steeped in strong acid, is converted into a substance of great explosive power. It is also soluble in alcohol and ether. One end of the glass tube was, of course, open to the external air; and at the other end of it he placed an aspirator, a contrivance for causing a current of the external air to pass through the tube. He kept this apparatus going for four-and-twenty hours, and then removed the _dusted_ gun-cotton, and dissolved it in alcohol and ether. He then allowed this to stand for a few hours, and the result was, that a very fine dust was gradually deposited at the bottom of it. That dust, on being transferred to the stage of a microscope, was found to contain an enormous number of starch grains. You know that the materials of our food and the greater portion of plants are composed of starch, and we are constantly making use of it in a variety of ways, so that there is always a quantity of it suspended in the air. It is these starch grains which form many of those bright specks that we see dancing in a ray of light sometimes. But besides these, M. Pasteur found also an immense number of other organic substances such as spores of fungi, which had been floating about in the air and had got caged in this way. He went farther, and said to himself, "If these really are the things that give rise to the appearance of spontaneous generation, I ought to be able to take a ball of this dusted gun-cotton and put it into one of my vessels, containing that boiled infusion which has been kept away from the air, and in which no infusoria are at present developed, and then, if I am right, the introduction of this gun-cotton will give rise to organisms." Accordingly, he took one of these vessels of infusion, which had been kept eighteen months, without the least appearance of life in it, and by a most ingenious contrivance, he managed to break it open and introduce such a ball of gun-cotton, without allowing the infusion or the cotton ball to come into contact with any air but that which had been subjected to a red heat, and in twenty-four hours he had the satisfaction of finding all the indications of what had been hitherto called spontaneous generation. He had succeeded in catching the germs and developing organisms in the way ho had anticipated. It now struck him that the truth of his conclusions might be demonstrated without all the apparatus he had employed. To do this, he took some decaying animal or vegetable substance, such as urine, which is an extremely decomposable substance, or the juice of yeast, or perhaps some other artificial preparation, and filled a vessel having a long tubular neck with it. He then boiled the liquid and bent that long neck into an S shape or zig-zag, leaving it open at the end. The infusion then gave no trace of any appearance of spontaneous generation, however long it might be left, as all the germs in the air were deposited in the beginning of the bent neck. He then cut the tube close to the vessel, and allowed the ordinary air to have free and direct access; and the result of that was the appearance of organisms in it, as soon as the infusion had been allowed to stand long enough to allow of the growth of those it received from the air, which was about forty-eight hours. The result of M. Pasteur's experiments proved, therefore, in the most conclusive manner, that all the appearances of spontaneous generation arose from nothing more than the deposition of the germs of organisms which were constantly floating in the air. To this conclusion, however, the objection was made, that if that were the cause, then the air would contain such an enormous number of these germs, that it would be a continual fog. But M. Pasteur replied that they are not there in anything like the number we might suppose, and that an exaggerated view has been held on that subject; he showed that the chances of animal or vegetable life appearing in infusions, depend entirely on the conditions under which they are exposed. If they are exposed to the ordinary atmosphere around us, why, of course, you may have organisms appearing early. But, on the other hand, if they are exposed to air at a great height, or in some very quiet cellar, you will often not find a single trace of life. So that M. Pasteur arrived at last at the clear and definite result, that all these appearances are like the case of the worms in the piece of meat, which was refuted by Redi, simply germs carried by the air and deposited in the liquids in which they afterwards appear. For my own part, I conceive that, with the particulars of M. Pasteur's experiments before us, we cannot fail to arrive at his conclusions; and that the doctrine of spontaneous generation has received a final _coup de grâce_. You, of course, understand that all this in no way interferes with the _possibility_ of the fabrication of organic matters by the direct method to which I have referred, remote as that possibility may be. IV. THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND VARIATION The inquiry which we undertook, at our last meeting, into the state of our knowledge of the causes of the phenomena of organic nature,--of the past and of the present,--resolved itself into two subsidiary inquiries: the first was, whether we know anything, either historically or experimentally, of the mode of origin of living beings; the second subsidiary inquiry was, whether, granting the origin, we know anything about the perpetuation and modifications of the forms of organic beings. The reply which I had to give to the first question was altogether negative, and the chief result of my last lecture was, that, neither historically nor experimentally, do we at present know anything whatsoever about the origin of living forms. We saw that, historically, we are not likely to know anything about it, although we may perhaps learn something experimentally; but that at present we are an enormous distance from the goal I indicated. I now, then, take up the next question, What do we know of the reproduction, the perpetuation, and the modifications of the forms of living beings, supposing that we have put the question as to their origination on one side, and have assumed that at present the causes of their origination are beyond us, and that we know nothing about them? Upon this question the state of our knowledge is extremely different; it is exceedingly large: and, if not complete, our experience is certainly most extensive. It would be impossible to lay it all before you, and the most I can do, or need do to-night, is to take up the principal points and put them before you with such prominence as may subserve the purposes of our present argument. The method of the perpetuation of organic beings is of two kinds,--the non-sexual and the sexual. In the first the perpetuation takes place from and by a particular act of an individual organism, which sometimes may not be classed as belonging to any sex at all. In the second case, it is in consequence of the mutual action and interaction of certain portions of the organisms of usually two distinct individuals,--the male and the female. The cases of non-sexual perpetuation are by no means so common as the cases of sexual perpetuation; and they are by no means so common in the animal as in the vegetable world. You are all probably familiar with the fact, as a matter of experience, that you can propagate plants by means of what are called "cuttings"; for example, that by taking a cutting from a geranium plant, and rearing it properly, by supplying it with light and warmth and nourishment from the earth, it grows up and takes the form of its parent, having all the properties and peculiarities of the original plant. Sometimes this process, which the gardener performs artificially, takes place naturally; that is to say, a little bulb, or portion of the plant, detaches itself, drops off, and becomes capable of growing as a separate thing. That is the case with many bulbous plants, which throw off in this way secondary bulbs, which are lodged in the ground and become developed into plants. This is a non-sexual process, and from it results the repetition or reproduction of the form of the original being from which the bulb proceeds. Among animals the same thing takes place. Among the lower forms of animal life, the infusorial animalculæ we have already spoken of throw off certain portions, or break themselves up in various directions, sometimes transversely or sometimes longitudinally; or they may give off buds, which detach themselves and develop into their proper forms. There is the common fresh-water polype, for instance, which multiplies itself in this way. Just in the same way as the gardener is able to multiply and reproduce the peculiarities and characters of particular plants by means of cuttings, so can the physiological experimentalist--as was shown by the Abbé Trembley many years ago--so can he do the same thing with many of the lower forms of animal life. M. de Trembley showed that you could take a polype and cut it into two, or four, or many pieces, mutilating it in all directions, and the pieces would still grow up and reproduce completely the original form of the animal. These are all cases of non-sexual multiplication, and there are other instances, and still more extraordinary ones, in which this process takes place naturally, in a more hidden, a more recondite kind of way. You are all of you familiar with that little green insect, the _Aphis_ or blight, as it is called. These little animals, during a very considerable part of their existence, multiply themselves by means of a kind of internal budding, the buds being developed into essentially non-sexual animals, which are neither male nor female; they become converted into young _Aphides_, which repeat the process, and their offspring after them, and so on again; you may go on for nine or ten, or even twenty or more successions; and there is no very good reason to say how soon it might terminate, or how long it might not go on if the proper conditions of warmth and nourishment were kept up. Sexual reproduction is quite a distinct matter. Here, in all these cases, what is required is the detachment of two portions of the parental organisms, which portions we know as the egg or the spermatozoon. In plants it is the ovule and the pollen-grain, as in the flowering plants, or the ovule and the antherozooid, as in the flowerless. Among all forms of animal life, the spermatozoa proceed from the male sex, and the egg is the product of the female. Now, what is remarkable about this mode of reproduction is this, that the egg by itself, or the spermatozoa by themselves, are unable to assume the parental form; but if they be brought into contact with one another, the effect of the mixture of organic substances proceeding from two sources appears to confer an altogether new vigour to the mixed product. This process is brought about, as we all know, by the sexual intercourse of the two sexes, and is called the act of impregnation. The result of this act on the part of the male and female is, that the formation of a new being is set up in the ovule or egg; this ovule or egg soon begins to be divided and subdivided, and to be fashioned into various complex organs, and eventually to develop into the form of one of its parents, as I explained in the first lecture. These are the processes by which the perpetuation of organic beings is secured. Why there should be the two modes--why this re-invigoration should be required on the part of the female element we do not know; but it is most assuredly the fact, and it is presumable, that, however long the process of non-sexual multiplication could be continued--I say there is good reason to believe that it would come to an end if a new commencement were not obtained by a conjunction of the two sexual elements. That character which is common to these two distinct processes is this, that, whether we consider the reproduction, or perpetuation, or modification of organic beings as they take place non-sexually, or as they may take place sexually--in either case, I say, the offspring has a constant tendency to assume, speaking generally, the character of the parent. As I said just now, if you take a slip of a plant, and tend it with care, it will eventually grow up and develop into a plant like that from which it had sprung; and this tendency is so strong that, as gardeners know, this mode of multiplying by means of cuttings is the only secure mode of propagating very many varieties of plants; the peculiarity of the primitive stock seems to be better preserved if you propagate it by means of a slip than if you resort to the sexual mode. Again, in experiments upon the lower animals, such as the polype, to which I have referred, it is most extraordinary that, although cut up into various pieces, each particular piece will grow up into the form of the primitive stock; the head, if separated, will reproduce the body and the tail; and if you cut off the tail, you will find that that will reproduce the body and all the rest of the members, without in any way deviating from the plan of the organism from which these portions have been detached. And so far does this go, that some experimentalists have carefully examined the lower orders of animals,--among them the Abbé Spallanzani, who made a number of experiments upon snails and salamanders,--and have found that they might mutilate them to an incredible extent; that you might cut off the jaw or the greater part of the head, or the leg or the tail, and repeat the experiment several times, perhaps cutting off the same member again and again; and yet each of those types would be reproduced according to the primitive type: Nature making no mistake, never putting on a fresh kind of leg, or head, or tail, but always tending to repeat and to return to the primitive type. It is the same in sexual reproduction: it is a matter of perfectly common experience, that the tendency on the part of the offspring always is, speaking broadly, to reproduce the form of the parents. The proverb has it that the thistle does not bring forth grapes; so, among ourselves, there is always a likeness, more or less marked and distinct, between children and their parents. That is a matter of familiar and ordinary observation. We notice the same thing occurring in the cases of the domestic animals--dogs, for instance, and their offspring. In all these cases of propagation and perpetuation, there seems to be a tendency in the offspring to take the characters of the parental organisms. To that tendency a special name is given--and as I may very often use it, I will write it up here on this black-board that you may remember it--it is called _Atavism_; it expresses this tendency to revert to the ancestral type, and comes from the Latin word _atavus_, ancestor. Well, this _Atavism_ which I shall speak of, is, as I said before, one of the most marked and striking tendencies of organic beings; but, side by side with this hereditary tendency there is an equally distinct and remarkable tendency to variation. The tendency to reproduce the original stock has, as it were, its limits, and side by side with it there is a tendency to vary in certain directions, as if there were two opposing powers working upon the organic being, one tending to take it in a straight line, and the other tending to make it diverge from that straight line, first to one side and then to the other. So that you see these two tendencies need not precisely contradict one another, as the ultimate result may not always be very remote from what would have been the case if the line had been quite straight. This tendency to variation is less marked in that mode of propagation which takes place non-sexually; it is in that mode that the minor characters of animal and vegetable structures are most completely preserved. Still, it will happen sometimes, that the gardener, when he has planted a cutting of some favourite plant, will find, contrary to his expectation, that the slip grows up a little different from the primitive stock--that it produces flowers of a different colour or make, or some deviation in one way or another. This is what is called the "sporting" of plants. In animals the phenomena of non-sexual propagation are so obscure, that at present we cannot be said to know much about them; but if we turn to that mode of perpetuation which results from the sexual process, then we find variation a perfectly constant occurrence, to a certain extent; and, indeed, I think that a certain amount of variation from the primitive stock is the necessary result of the method of sexual propagation itself; for, inasmuch as the thing propagated proceeds from two organisms of different sexes and different makes and temperaments, and as the offspring is to be either of one sex or the other, it is quite clear that it cannot be an exact diagonal of the two, or it would be of no sex at all; it cannot be an exact intermediate form between that of each of its parents--it must deviate to one side or the other. You do not find that the male follows the precise type of the male parent, nor does the female always inherit the precise characteristics of the mother,--there is always a proportion of the female character in the male offspring, and of the male character in the female offspring. That must be quite plain to all of you who have looked at all attentively on your own children or those of your neighbours; you will have noticed how very often it may happen that the son shall exhibit the maternal type of character, or the daughter possess the characteristics of the father's family. There are all sorts of intermixtures and intermediate conditions between the two, where complexion, or beauty, or fifty other different peculiarities belonging to either side of the house, are reproduced in other members of the same family. Indeed, it is sometimes to be remarked in this kind of variation, that the variety belongs, strictly speaking, to neither of the immediate parents; you will see a child in a family who is not like either its father or its mother; but some old person who knew its grandfather or grandmother, or, it may be, an uncle, or, perhaps, even a more distant relative will see a great similarity between the child and one of these. In this way it constantly happens that the characteristic of some previous member of the family comes out and is reproduced and recognised in the most unexpected manner. But apart from that matter of general experience, there are some cases which put that curious mixture in a very clear light. You are aware that the offspring of the ass and the horse, or rather of the he-ass and the mare, is what is called a mule; and, on the other hand, the offspring of the stallion and the she-ass is what is called a hinny. It is a very rare thing in this country to see a hinny. I never saw one myself; but they have been very carefully studied. Now, the curious thing is this, that although you have the same elements in the experiment in each case, the offspring is entirely different in character, according as the male influence comes from the ass or the horse. Where the ass is the male, as in the case of the mule, you find that the head is like that of the ass, that the ears are long, the tail is tufted at the end, the feet are small, and the voice is an unmistakable bray; these are all points of similarity to the ass; but, on the other hand, the barrel of the body and the cut of the neck are much more like those of the mare. Then, if you look at the hinny,--the result of the union of the stallion and the she-ass, then you find it is the horse that has the predominance; that the head is more like that of the horse, the ears are shorter, the legs coarser, and the type is altogether altered; while the voice, instead of being a bray, is the ordinary neigh of the horse. Here, you see, is a most curious thing: you take exactly the same elements, ass and horse, but you combine the sexes in a different manner, and the result is modified accordingly. You have in this case, however, a result which is not general and universal--there is usually an important preponderance, but not always on the same side. Here, then, is one intelligible, and, perhaps, necessary cause of variation: the fact, that there are two sexes sharing in the production of the offspring, and that the share taken by each is different and variable, not only for each combination, but also for different members of the same family. Secondly, there is a variation, to a certain extent--though, in all probability, the influence of this cause has been very much exaggerated--but there is no doubt that variation is produced, to a certain extent, by what are commonly known as external conditions,--such as temperature, food, warmth, and moisture. In the long run, every variation depends, in some sense, upon external conditions, seeing that everything has a cause of its own. I use the term "external conditions" now in the sense in which it is ordinarily employed: certain it is, that external conditions have a definite effect. You may take a plant which has single flowers, and by dealing with the soil, and nourishment, and so on, you may by and by convert single flowers into double flowers, and make thorns shoot out into branches. You may thicken or make various modifications in the shape of the fruit. In animals, too, you may produce analogous changes in this way, as in the case of that deep bronze colour which persons rarely lose after having passed any length of time in tropical countries. You may also alter the development of the muscles very much, by dint of training; all the world knows that exercise has a great effect in this way; we always expect to find the arm of a blacksmith hard and wiry, and possessing a large development of the brachial muscles. No doubt training, which is one of the forms of external conditions, converts what are originally only instructions, teachings, into habits, or, in other words, into organisations, to a great extent; but this second cause of variation cannot be considered to be by any means a large one. The third cause that I have to mention, however, is a very extensive one. It is one that, for want of a better name, has been called "spontaneous variation"; which means that when we do not know anything about the cause of phenomena, we call it spontaneous. In the orderly chain of causes and effects in this world, there are very few things of which it can be said with truth that they are spontaneous. Certainly not in these physical matters--in these there is nothing of the kind--everything depends on previous conditions. But when we cannot trace the cause of phenomena, we call them spontaneous. Of these variations, multitudinous as they are, but little is known with perfect accuracy. I will mention to you some two or three cases, because they are very remarkable in themselves, and also because I shall want to use them afterwards. Réaumur, a famous French naturalist, a great many years ago, in an essay which he wrote upon the art of hatching chickens--which was indeed a very curious essay--had occasion to speak of variations and monstrosities. One very remarkable case had come under his notice of a variation in the form of a human member, in the person of a Maltese, of the name of Gratio Kelleia, who was born with six fingers upon each hand, and the like number of toes to each of his feet. That was a case of spontaneous variation. Nobody knows why he was born with that number of fingers and toes, and as we don't know, we call it a case of "spontaneous" variation. There is another remarkable case also. I select these, because they happen to have been observed and noted very carefully at the time. It frequently happens that a variation occurs, but the persons who notice it do not take any care in noting down the particulars, until at length, when inquiries come to be made, the exact circumstances are forgotten; and hence, multitudinous as may be such "spontaneous" variations, it is exceedingly difficult to get at the origin of them. The second case is one of which you may find the whole details in the "Philosophical Transactions" for the year 1813, in a paper communicated by Colonel Humphrey to the President of the Royal Society--"On a new Variety in the Breed of Sheep," giving an account of a very remarkable breed of sheep, which at one time was well known in the northern states of America, and which went by the name of the Ancon or the Otter breed of sheep. In the year 1791, there was a farmer of the name of Seth Wright in Massachusetts, who had a flock of sheep, consisting of a ram and, I think, of some twelve or thirteen ewes. Of this flock of ewes, one at the breeding-time bore a lamb which was very singularly formed; it had a very long body, very short legs, and those legs were bowed. I will tell you by and by how this singular variation in the breed of sheep came to be noted, and to have the prominence that it now has. For the present, I mention only these two cases; but the extent of variation in the breed of animals is perfectly obvious to any one who has studied natural history with ordinary attention, or to any person who compares animals with others of the same kind. It is strictly true that there are never any two specimens which are exactly alike; however similar, they will always differ in some certain particular. Now let us go back to Atavism--to the hereditary tendency I spoke of. What will come of a variation when you breed from it, when Atavism comes, if I may say so, to intersect variation? The two cases of which I have mentioned the history give a most excellent illustration of what occurs. Gratio Kelleia, the Maltese, married when he was twenty-two years of age, and, as I suppose there were no six-fingered ladies in Malta, he married an ordinary five-fingered person. The result of that marriage was four children; the first, who was christened Salvator, had six fingers and six toes, like his father; the second was George, who had five fingers and toes, but one of them was deformed, showing a tendency to variation; the third was Andrè; he had five fingers and five toes, quite perfect; the fourth was a girl, Marie; she had five fingers and five toes, but her thumbs were deformed, showing a tendency toward the sixth. These children grew up, and when they came to adult years, they all married, and of course it happened that they all married five-fingered and five-toed persons. Now let us see what were the results. Salvator had four children; they were two boys, a girl, and another boy; the first two boys and the girl were six-fingered and six-toed like their grandfather; the fourth boy had only five fingers and five toes. George had only four children; there were two girls with six fingers and six toes; there was one girl with six fingers and five toes on the right side, and five fingers and five toes on the left side, so that she was half and half. The last, a boy, had five fingers and five toes. The third, Andrè, you will recollect, was perfectly well-formed, and he had many children whose hands and feet were all regularly developed. Marie, the last, who, of course, married a man who had only five fingers, had four children; the first, a boy, was born with six toes, but the other three were normal. Now observe what very extraordinary phenomena are presented here. You have an accidental variation giving rise to what you may call a monstrosity; you have that monstrosity or variation diluted in the first instance by an admixture with a female of normal construction, and you would naturally expect that, in the results of such an union, the monstrosity, if repeated, would be in equal proportion with the normal type; that is to say, that the children would be half and half, some taking the peculiarity of the father, and the others being of the purely normal type of the mother; but you see we have a great preponderance of the abnormal type. Well, this comes to be mixed once more with the pure, the normal type, and the abnormal is again produced in large proportion, notwithstanding the second dilution. Now what would have happened if these abnormal types had intermarried with each other; that is to say, suppose the two boys of Salvator had taken it into their heads to marry their first cousins, the two first girls of George, their uncle? You will remember that these are all of the abnormal type of their grandfather. The result would probably have been, that their offspring would have been in every case a further development of that abnormal type. You see it is only in the fourth, in the person of Marie, that the tendency, when it appears but slightly in the second generation, is washed out in the third, while the progeny of Andrè, who escaped in the first instance, escape altogether. We have in this case a good example of nature's tendency to the perpetuation of a variation. Here it is certainly a variation which earned with it no use or benefit; and yet you see the tendency to perpetuation may be so strong, that, notwithstanding a great admixture of pure blood, the variety continues itself up to the third generation, which is largely marked with it. In this case, as I have said, there was no means of the second generation intermarrying with any but five-fingered persons, and the question naturally suggests itself, What would have been the result of such marriage? Réaumur narrates this case only as far as the third generation. Certainly it would have been an exceedingly curious thing if we could have traced this matter any further; had the cousins intermarried, a six-fingered variety of the human race might have been set up. To show you that this supposition is by no means an unreasonable one, let me now point out what took place in the case of Seth Wright's sheep, where it happened to be a matter of moment to him to obtain a breed or raise a flock of sheep like that accidental variety that I have described--and I will tell you why. In that part of Massachusetts where Seth Wright was living, the fields were separated by fences, and the sheep, which were very active and robust, would roam abroad, and without much difficulty jump over these fences into other people's farms. As a matter of course, this exuberant activity on the part of the sheep constantly gave rise to all sorts of quarrels, bickerings, and contentions among the farmers of the neighbourhood; so it occurred to Seth Wright, who was, like his successors, more or less 'cute, that if he could get a stock of sheep like those with the bandy legs, they would not be able to jump over the fences so readily; and he acted upon that idea. He killed his old ram, and as soon as the young one arrived at maturity, he bred altogether from it. The result was even more striking than in the human experiment which I mentioned just now. Colonel Humphreys testifies that it always happened that the offspring were either pure Ancons or pure ordinary sheep; that in no case was there any mixing of the Ancons with the others. In consequence of this, in the course of a very few years, the farmer was able to get a very considerable flock of this variety, and a large number of them were spread throughout Massachusetts. Most unfortunately, however--I suppose it was because they were so common--nobody took enough notice of them to preserve their skeletons; and although Colonel Humphreys states that he sent a skeleton to the President of the Royal Society at the same time that he forwarded his paper, I am afraid that the variety has entirely disappeared; for a short time after these sheep had become prevalent in that district, the Merino sheep were introduced; and as their wool was much more valuable, and as they were a quiet race of sheep, and showed no tendency to trespasser jump over fences, the Otter breed of sheep, the wool of which was inferior to that of the Merino, was gradually allowed to die out. You see that these facts illustrate perfectly well what may be done if you take care to breed from stocks that are similar to each other. After having got a variation, if, by crossing a variation with the original stock, you multiply that variation, and then take care to keep that variation distinct from the original stock, and make them breed together,--then you may almost certainly produce a race whose tendency to continue the variation is exceedingly strong. This is what is called "selection"; and it is by exactly the same process as that by which Seth Wright bred his Ancon sheep, that our breeds of cattle, dogs, and fowls are obtained. There are some possibilities of exception, but still, speaking broadly, I may say that this is the way in which all our varied races of domestic animals have arisen; and you must understand that it is not one peculiarity or one characteristic alone in which animals may vary. There is not a single peculiarity or characteristic of any kind, bodily or mental, in which offspring may not vary to a certain extent from the parent and other animals. Among ourselves this is well known. The simplest physical peculiarity is mostly reproduced. I know a case of a woman who has the lobe of one of her ears a little flattened. An ordinary observer might scarcely notice it, and yet every one of her children has an approximation to the same peculiarity to some extent. If you look at the other extreme, too, the gravest diseases, such as gout, scrofula, and consumption, may be handed down with just the same certainty and persistence as we noticed in the perpetuation of the bandy legs of the Ancon sheep. However, these facts are best illustrated in animals, and the extent of the variation, as is well known, is very remarkable in dogs. For example, there are some dogs very much smaller than others; indeed, the variation is so enormous that probably the smallest dog would be about the size of the head of the largest; there are very great variations in the structural forms not only of the skeleton but also in the shape of the skull, and in the proportions of the face and the disposition of the teeth. The Pointer, the Retriever, Bulldog, and the Terrier differ very greatly, and yet there is every reason to believe that every one of these races has arisen from the same source,--that all the most important races have arisen by this selective breeding from accidental variation. A still more striking case of what may be done by selective breeding, and it is a better case, because there is no chance of that partial infusion of error to which I alluded, has been studied very carefully by Mr. Darwin,--the case of the domestic pigeons. I dare say there may be some among you who may be pigeon _fanciers_, and I wish you to understand that in approaching the subject, I would speak with all humility and hesitation, as I regret to say that I am not a pigeon fancier. I know it is a great art and mystery, and a thing upon which a man must not speak lightly; but I shall endeavour, as far as my understanding goes, to give you a summary of the published and unpublished information which I have gained from Mr. Darwin. Among the enormous variety,--I believe there are somewhere about a hundred and fifty kinds of pigeons,--there are four kinds which may be selected as representing the extremest divergences of one kind from another. Their names are the Carrier, the Pouter, the Fantail, and the Tumbler. In these large diagrams that I have here they are each represented in their relative sizes to each other. This first one is the Carrier; you will notice this large excrescence on its beak; it has a comparatively small head; there is a bare space round the eyes; it has a long neck, a very long beak, very strong legs, large feet, long wings, and so on. The second one is the Pouter, a very large bird, with very long legs and beak. It is called the Pouter because it is in the habit of causing its gullet to swell up by inflating it with air. I should tell you that all pigeons have a tendency to do this at times, but in the Pouter it is carried to an enormous extent. The birds appear to be quite proud of their power of swelling and puffing themselves out in this way; and I think it is about as droll a sight as you can well see to look at a cage full of these pigeons puffing and blowing themselves out in this ridiculous manner. This diagram is a representation of the third kind I mentioned--the Fantail. It is, you see, a small bird, with exceedingly small legs and a very small beak. It is most curiously distinguished by the size and extent of its tail, which, instead of containing twelve feathers, may have many more,--say thirty, or even more--I believe there are some with as many as forty-two. This bird has a curious habit of spreading out the feathers of its tail in such a way that they reach forward and touch its head; and if this can be accomplished, I believe it is looked upon as a point of great beauty. But here is the last great variety,--the Tumbler; and of that great variety, one of the principal kinds, and one most prized, is the specimen represented here--the short-faced Tumbler. Its beak, you see, is reduced to a mere nothing. Just compare the beak of this one and that of the first one, the Carrier--I believe the orthodox comparison of the head and beak of a thoroughly well-bred Tumbler is to stick an oat into a cherry, and that will give you the proper relative proportions of the beak and head. The feet and legs are exceedingly small, and the bird appears to be quite a dwarf when placed side by side with this great Carrier. These are differences enough in regard to their external appearance; but these differences are by no means the whole or even the most important of the differences which obtain between these birds. There is hardly a single point of their structure which has not become more or less altered; and to give you an idea of how extensive these alterations are, I have here some very good skeletons, for which I am indebted to my friend, Mr. Tegetmeier, a great authority in these matters; by means of which, if you examine them by and by, you will be able to see the enormous difference in their bony structures. I had the privilege, some time ago, of access to some important MSS. of Mr. Darwin, who, I may tell you, has taken very great pains and spent much valuable time and attention on the investigation of these variations, and getting together all the facts that bear upon them. I obtained from these MSS. the following summary of the differences between the domestic breeds of pigeons; that is to say, a notification of the various points in which their organisation differs. In the first place, the back of the skull may differ a good deal, and the development of the bones of the face may vary a great deal; the back varies a good deal; the shape of the lower jaw varies; the tongue varies very greatly, not only in correlation to the length and size of the beak, but it seems also to have a kind of independent variation of its own. Then the amount of naked skin round the eyes, and at the base of the beak, may vary enormously; so may the length of the eyelids, the shape of the nostrils, and the length of the neck. I have already noticed the habit of blowing out the gullet, so remarkable in the Pouter, and comparatively so in the others. There are great differences, too, in the size of the female and the male, the shape of the body, the number and width of the processes of the ribs, the development of the ribs, and the size, shape, and development of the breastbone. We may notice, too--and I mention the fact because it has been disputed by what is assumed to be high authority,--the variation in the number of the sacral vertebrae. The number of these varies from eleven to fourteen, and that without any diminution in the number of the vertebrae of the back or of the tail. Then the number and position of the tail-feathers may vary enormously, and so may the number of the primary and secondary feathers of the wings. Again, the length of the feet and of the beak,--although they have no relation to each other, yet appear to go together,--that is, you have a long beak wherever you have long feet. There are differences also in the periods of the acquirement of the perfect plumage--the size and shape of the eggs--the nature of flight, and the powers of flight--so-called _"homing"_ birds having enormous flying powers; [Footnote: The _"Carrier,"_ I learn from Mr. Tegetmeier, does not _carry_; a high-bred bird of this breed being but a poor flier. The birds which fly long distances, and come home--"homing" birds-and are consequently used as carriers, are not "carriers" in the fancy sense.] while, on the other hand, the little Tumbler is so called because of its extraordinary faculty of turning head over heels in the air, instead of pursuing a direct course. And, lastly, the dispositions and voices of the birds may vary. Thus the case of the pigeons shows you that there is hardly a single particular--whether of instinct, or habit, or bony structure, or of plumage--of either the internal economy or the external shape, in which some variation or change may not take place, which, by selective breeding, may become perpetuated, and form the foundation of, and give rise to, a new race. If you carry in your mind's eye these four varieties of pigeons, you will bear with you as good a notion as you can have, perhaps, of the enormous extent to which a deviation from a primitive type may be carried by means of this process of selective breeding. V. THE CONDITIONS OF EXISTENCE AS AFFECTING THE PERPETUATION OF LIVING BEINGS In the last Lecture I endeavoured to prove to you that, while, as a general rule, organic beings tend to reproduce their kind, there is in them, also, a constantly recurring tendency to vary--to vary to a greater or to a less extent. Such a variety, I pointed out to you, might arise from causes which we do not understand; we therefore called it spontaneous; and it might come into existence as a definite and marked thing, without any gradations between itself and the form which preceded it. I further pointed out, that such a variety having once arisen, might be perpetuated to some extent, and indeed to a very marked extent, without any direct interference, or without any exercise of that process which we called selection. And then I stated further, that by such selection, when exercised artificially--if you took care to breed only from those forms which presented the same peculiarities of any variety which had arisen in this manner--the variation might be perpetuated, as far as we can see, indefinitely. The next question, and it is an important one for us, is this: Is there any limit to the amount of variation from the primitive stock which can be produced by this process of selective breeding? In considering this question, it will be useful to class the characteristics, in respect of which organic beings vary, under two heads: we may consider structural characteristics, and we may consider physiological characteristics. In the first place, as regards structural characteristics, I endeavoured to show you, by the skeletons which I had upon the table, and by reference to a great many well-ascertained facts, that the different breeds of Pigeons, the Carriers, Pouters, and Tumblers, might vary in any of their internal and important structural characters to a very great degree; not only might there be changes in the proportions of the skull, and the characters of the feet and beaks, and so on; but that there might be an absolute difference in the number of the vertebrae of the back, as in the sacral vertebras of the Pouter; and so great is the extent of the variation in these and similar characters that I pointed out to you, by reference to the skeletons and the diagrams, that these extreme varieties may absolutely differ more from one another in their structural characters than do what naturalists call distinct SPECIES of pigeons; that is to say, that they differ so much in structure that there is a greater difference between the Pouter and the Tumbler than there is between such wild and distinct forms as the Rock Pigeon or the Ring Pigeon, or the Ring Pigeon and the Stock Dove; and indeed the differences are of greater value than this, for the structural differences between these domesticated pigeons are such as would be admitted by a naturalist, supposing he knew nothing at all about their origin, to entitle them to constitute even distinct genera. As I have used this term SPECIES, and shall probably use it a good deal, I had better perhaps devote a word or two to explaining what I mean by it. Animals and plants are divided into groups, which become gradually smaller, beginning with a KINGDOM, which is divided into SUB-KINGDOMS; then come the smaller divisions called PROVINCES; and so on from a PROVINCE to a CLASS, from a CLASS to an ORDER, from ORDERS to FAMILIES, and from these to GENERA, until we come at length to the smallest groups of animals which can be defined one from the other by constant characters, which are not sexual; and these are what naturalists call SPECIES in practice, whatever they may do in theory. If, in a state of nature, you find any two groups of living beings, which are separated one from the other by some constantly-recurring characteristic, I don't care how slight and trivial, so long as it is defined and constant, and does not depend on sexual peculiarities, then all naturalists agree in calling them two species; that is what is meant by the use of the word species--that is to say, it is, for the practical naturalist, a mere question of structural differences. [Footnote: I lay stress here on the _practical_ signification of "Species." Whether a physiological test between species exist or not, it is hardly ever applicable by the practical naturalist.] We have seen now--to repeat this point once more, and it is very essential that we should rightly understand it--we have seen that breeds, known to have been derived from a common stock by selection, may be as different in their structure from the original stock as species may be distinct from each other. But is the like true of the physiological characteristics of animals? Do the physiological differences of varieties amount in degree to those observed between forms which naturalists call distinct species? This is a most important point for us to consider. As regards the great majority of physiological characteristics, there is no doubt that they are capable of being developed, increased, and modified by selection. There is no doubt that breeds may be made as different as species in many physiological characters. I have already pointed out to you very briefly the different habits of the breeds of Pigeons, all of which depend upon their physiological peculiarities--as the peculiar habit of tumbling, in the Tumbler--the peculiarities of flight, in the "homing" birds--the strange habit of spreading out the tail, and walking in a peculiar fashion, in the Fantail--and, lastly, the habit of blowing out the gullet, so characteristic of the Pouter. These are all due to physiological modifications, and in all these respects these birds differ as much from each other as any two ordinary species do. So with Dogs in their habits and instincts. It is a physiological peculiarity which leads the Greyhound to chase its prey by sight--that enables the Beagle to track it by the scent--that impels the Terrier to its rat-hunting propensity--and that leads the Retriever to its habit of retrieving. These habits and instincts are all the results of physiological differences and peculiarities, which have been developed from a common stock, at least there is every reason to believe so. But it is a most singular circumstance, that while you may run through almost the whole series of physiological processes, without finding a check to your argument, you come at last to a point where you do find a check, and that is in the reproductive processes. For there is a most singular circumstance in respect to natural species--at least about some of them--and it would be sufficient for the purposes of this argument if it were true of only one of them, but there is, in fact, a great number of such cases--and that is, that, similar as they may appear to be to mere races or breeds, they present a marked peculiarity in the reproductive process. If you breed from the male and female of the same race, you of course have offspring of the like kind, and if you make the offspring breed together, you obtain the same result, and if you breed from these again, you will still have the same kind of offspring; there is no check. But if you take members of two distinct species, however similar they may be to each other, and make them breed together, you will find a check, with some modifications and exceptions, however, which I shall speak of presently. If you cross two such species with each other, then--although you may get offspring in the case of the first cross, yet, if you attempt to breed from the products of that crossing, which are what are called HYBRIDS--that is, if you couple a male and a female hybrid--then the result is that in ninety-nine cases out of a hundred you will get no offspring at all; there will be no result whatsoever. The reason of this is quite obvious in some cases; the male hybrids, although possessing all the external appearances and characteristics of perfect animals, are physiologically imperfect and deficient in the structural parts of the reproductive elements necessary to generation. It is said to be invariably the case with the male mule, the cross between the Ass and the Mare; and hence it is, that, although crossing the Horse with the Ass is easy enough, and is constantly done, as far as I am aware, if you take two mules, a male and a female, and endeavour to breed from them, you get no offspring whatever; no generation will take place. This is what is called the sterility of the hybrids between two distinct species. You see that this is a very extraordinary circumstance; one does not see why it should be. The common teleological explanation is, that it is to prevent the impurity of the blood resulting from the crossing of one species with another, but you see it does not in reality do anything of the kind. There is nothing in this fact that hybrids cannot breed with each other, to establish such a theory; there is nothing to prevent the Horse breeding with the Ass, or the Ass with the Horse. So that this explanation breaks down, as a great many explanations of this kind do, that are only founded on mere assumptions. Thus you see that there is a great difference between "mongrels," which are crosses between distinct races, and "hybrids," which are crosses between distinct species. The mongrels are, so far as we know, fertile with one another. But between species, in many cases, you cannot succeed in obtaining even the first cross; at any rate it is quite certain that the hybrids are often absolutely infertile one with another. Here is a feature, then, great or small as it may be, which distinguishes natural species of animals. Can we find any approximation to this in the different races known to be produced by selective breeding from a common stock? Up to the present time the answer to that question is absolutely a negative one. As far as we know at present, there is nothing approximating to this check. In crossing the breeds between the Fantail and the Pouter, the Carrier and the Tumbler, or any other variety or race you may name--so far as we know at present--there is no difficulty in breeding together the mongrels. Take the Carrier and the Fantail, for instance, and let them represent the Horse and the Ass in the case of distinct species; then you have, as the result of their breeding, the Carrier-Fantail mongrel,--we will say the male and female mongrel,--and, as far as we know, these two when crossed would not be less fertile than the original cross, or than Carrier with Carrier. Here, you see, is a physiological contrast between the races produced by selective modification and natural species. I shall inquire into the value of this fact, and of some modifying circumstances by and by; for the present I merely put it broadly before you. But while considering this question of the limitations of species, a word must be said about what is called RECURRENCE--the tendency of races which have been developed by selective breeding from varieties to return to their primitive type. This is supposed by many to put an absolute limit to the extent of selective and all other variations. People say, "It is all very well to talk about producing these different races, but you know very well that if you turned all these birds wild, these Pouters, and Carriers, and so on, they would all return to their primitive stock." This is very commonly assumed to be a fact, and it is an argument that is commonly brought forward as conclusive; but if you will take the trouble to inquire into it rather closely, I think you will find that it is not worth very much. The first question of course is, Do they thus return to the primitive stock? And commonly as the thing is assumed and accepted, it is extremely difficult to get anything like good evidence of it. It is constantly said, for example, that if domesticated Horses are turned wild, as they have been in some parts of Asia Minor and South America, that they return at once to the primitive stock from which they were bred. But the first answer that you make to this assumption is, to ask who knows what the primitive stock was; and the second answer is, that in that case the wild Horses of Asia Minor ought to be exactly like the wild Horses of South America. If they are both like the same thing, they ought manifestly to be like each other! The best authorities, however, tell you that it is quite different. The wild Horse of Asia is said to be of a dun colour, with a largish head, and a great many other peculiarities; while the best authorities on the wild Horses of South America tell you that there is no similarity between their wild Horses and those of Asia Minor; the cut of their heads is very different, and they are commonly chestnut or bay-coloured. It is quite clear, therefore, that as by these facts there ought to have been two primitive stocks, they go for nothing in support of the assumption that races recur to one primitive stock, and so far as this evidence is concerned, it falls to the ground. Suppose for a moment that it were so, and that domesticated races, when turned wild, did return to some common condition, I cannot see that this would prove much more than that similar conditions are likely to produce similar results; and that when you take back domesticated animals into what we call natural conditions, you do exactly the same thing as if you carefully undid all the work you had gone through, for the purpose of bringing the animal from its wild to its domesticated state. I do not see anything very wonderful in the fact, if it took all that trouble to get it from a wild state, that it should go back into its original state as soon as you removed the conditions which produced the variation to the domesticated form. There is an important fact, however, forcibly brought forward by Mr. Darwin, which has been noticed in connection with the breeding of domesticated pigeons; and it is, that however different these breeds of pigeons may be from each other, and we have already noticed the great differences in these breeds, that if, among any of those variations, you chance to have a blue pigeon turn up, it will be sure to have the black bars across the wings, which are characteristic of the original wild stock, the Rock Pigeon. Now, this is certainly a very remarkable circumstance; but I do not see myself how it tells very strongly either one way or the other. I think, in fact, that this argument in favour of recurrence to the primitive type might prove a great deal too much for those who so constantly bring it forward. For example, Mr. Darwin has very forcibly urged, that nothing is commoner than if you examine a dun horse--and I had an opportunity of verifying this illustration lately while in the islands of the West Highlands, where there are a great many dun horses--to find that horse exhibit a long black stripe down his back, very often stripes on his shoulder, and very often stripes on his legs. I, myself, saw a pony of this description a short time ago, in a baker's cart, near Rothesay, in Bute: it had the long stripe down the back, and stripes on the shoulders and legs, just like those of the Ass, the Quagga, and the Zebra. Now, if we interpret the theory of recurrence as applied to this case, might it not be said that here was a case of a variation exhibiting the characters and conditions of an animal occupying something like an intermediate position between the Horse, the Ass, the Quagga, and the Zebra, and from which these had been developed? In the same way with regard even to Man. Every anatomist will tell you that there is nothing commoner, in dissecting the human body, than to meet with what are called muscular variations--that is, if you dissect two bodies very carefully, you will probably find that the modes of attachment and insertion of the muscles are not exactly the same in both, there being great peculiarities in the mode in which the muscles are arranged; and it is very singular, that in some dissections of the human body you will come upon arrangements of the muscles very similar indeed to the same parts in the Apes. Is the conclusion in that case to be, that this is like the black bars in the case of the Pigeon, and that it indicates a recurrence to the primitive type from which the animals have been probably developed? Truly, I think that the opponents of modification and variation had better leave the argument of recurrence alone, or it may prove altogether too strong for them. To sum up,--the evidence as far as we have gone is against the argument as to any limit to divergences, so far as structure is concerned; and in favour of a physiological limitation. By selective breeding we can produce structural divergences as great as those of species, but we cannot produce equal physiological divergences. For the present I leave the question there. Now, the next problem that lies before us--and it is an extremely important one--is this: Does this selective breeding occur in nature? Because, if there is no proof of it, all that I have been telling you goes for nothing in accounting for the origin of species. Are natural causes competent to play the part of selection in perpetuating varieties? Here we labour under very great difficulties. In the last lecture I had occasion to point out to you the extreme difficulty of obtaining evidence even of the first origin of those varieties which we know to have occurred in domesticated animals. I told you, that almost always the origin of these varieties is overlooked, so that I could only produce two or three cases, as that of Gratio Kelleia and of the Ancon sheep. People forget, or do not take notice of them until they come to have a prominence; and if that is true of artificial cases, under our own eyes, and in animals in our own care, how much more difficult it must be to have at first hand good evidence of the origin of varieties in nature! Indeed, I do not know that it is possible by direct evidence to prove the origin of a variety in nature, or to prove selective breeding; but I will tell you what we can prove--and this comes to the same thing--that varieties exist in nature within the limits of species, and, what is more, that when a variety has come into existence in nature, there are natural causes and conditions, which are amply competent to play the part of a selective breeder; and although that is not quite the evidence that one would like to have--though it is not direct testimony--yet it is exceeding good and exceedingly powerful evidence in its way. As to the first point, of varieties existing among natural species, I might appeal to the universal experience of every naturalist, and of any person who has ever turned any attention at all to the characteristics of plants and animals in a state of nature; but I may as well take a few definite cases, and I will begin with Man himself. I am one of those who believe that, at present, there is no evidence whatever for saying, that mankind sprang originally from any more than a single pair; I must say, that I cannot see any good ground whatever, or even any tenable sort of evidence, for believing that there is more than one species of Man. Nevertheless, as you know, just as there are numbers of varieties in animals, so there are remarkable varieties of men. I speak not merely of those broad and distinct variations which you see at a glance. Everybody, of course, knows the difference between a Negro and a white man, and can tell a Chinaman from an Englishman. They each have peculiar characteristics of colour and physiognomy; but you must recollect that the characters of these races go very far deeper--they extend to the bony structure, and to the characters of that most important of all organs to us--the brain; so that, among men belonging to different races, or even within the same race, one man shall have a brain a third, or half, or even seventy per cent, bigger than another; and if you take the whole range of human brains, you will find a variation in some cases of a hundred per cent. Apart from these variations in the size of the brain, the characters of the skull vary. Thus if I draw the figures of a Mongol and of a Negro head on the blackboard, in the case of the last the breadth would be about seven-tenths, and in the other it would be nine-tenths of the total length. So that you see there is abundant evidence of variation among men in their natural condition. And if you turn to other animals there is just the same thing. The fox, for example, which has a very large geographical distribution all over Europe, and parts of Asia, and on the American Continent, varies greatly. There are mostly large foxes in the North, and smaller ones in the South. In Germany alone the foresters reckon some eight different sorts. Of the tiger, no one supposes that there is more than one species; they extend from the hottest parts of Bengal, into the dry, cold, bitter steppes of Siberia, into a latitude of 50°,--so that they may even prey upon the reindeer. These tigers have exceedingly different characteristics, but still they all keep their general features, so that there is no doubt as to their being tigers. The Siberian tiger has a thick fur, a small mane, and a longitudinal stripe down the back, while the tigers of Java and Sumatra differ in many important respects from the tigers of Northern Asia. So lions vary; so birds vary; and so, if you go further back and lower down in creation, you find that fishes vary. In different streams, in the same country even, you will find the trout to be quite different to each other and easily recognisable by those who fish in the particular streams. There is the same differences in leeches; leech collectors can easily point out to you the differences and the peculiarities which you yourself would probably pass by; so with fresh-water mussels; so, in fact, with every animal you can mention. In plants there is the same kind of variation. Take such a case even as the common bramble. The botanists are all at war about it; some of them wanting to make out that there are many species of it, and others maintaining that they are but many varieties of one species; and they cannot settle to this day which is a species and which is a variety! So that there can be no doubt whatsoever that any plant and any animal may vary in nature; that varieties may arise in the way I have described--as spontaneous varieties--and that those varieties may be perpetuated in the same way that I have shown you spontaneous varieties are perpetuated; I say, therefore, that there can be no doubt as to the origin and perpetuation of varieties in nature. But the question now is:--Does selection take place in nature? Is there anything like the operation of man in exercising selective breeding, taking place in nature? You will observe that, at present, I say nothing about species; I wish to confine myself to the consideration of the production of those natural races which everybody admits to exist. The question is, whether in nature there are causes competent to produce races, just in the same way as man is able to produce by selection, such races of animals as we have already noticed. When a variety has arisen, the CONDITIONS OF EXISTENCE are such as to exercise an influence which is exactly comparable to that of artificial selection. By Conditions of Existence I mean two things--there are conditions which are furnished by the physical, the inorganic world, and there are conditions of existence which are furnished by the organic world. There is, in the first place, CLIMATE; under that head I include only temperature and the varied amount of moisture of particular places. In the next place there is what is technically called STATION, which means--given the climate, the particular kind of place in which an animal or a plant lives or grows; for example, the station of a fish is in the water, of a fresh-water fish in fresh water; the station of a marine fish is in the sea, and a marine animal may have a station higher or deeper. So again with land animals: the differences in their stations are those of different soils and neighbourhoods; some being best adapted to a calcareous, and others to an arenaceous soil. The third condition of existence is FOOD, by which I mean food in the broadest sense, the supply of the materials necessary to the existence of an organic being; in the case of a plant the inorganic matters, such as carbonic acid, water, ammonia, and the earthy salts or salines; in the case of the animal the inorganic and organic matters, which we have seen they require; then these are all, at least the first two, what we may call the inorganic or physical conditions of existence. Food takes a mid-place, and then come the organic conditions; by which I mean the conditions which depend upon the state of the rest of the organic creation, upon the number and kind of living beings, with which an animal is surrounded. You may class these under two heads: there are organic beings, which operate as _opponents_, and there are organic beings which operate as _helpers_ to any given organic creature. The opponents may be of two kinds: there are the _indirect opponents_, which are what we may call _rivals_; and there are the _direct opponents_, those which strive to destroy the creature; and these we call _enemies_. By rivals I mean, of course, in the case of plants, those which require for their support the same kind of soil and station, and, among animals, those which require the same kind of station, or food, or climate; those are the indirect opponents; the direct opponents are, of course, those which prey upon an animal or vegetable. The _helpers_ may also be regarded as direct and indirect: in the case of a carnivorous animal, for example, a particular herbaceous plant may, in multiplying, be an indirect helper, by enabling the herbivora on which the carnivore preys to get more food, and thus to nourish the carnivore more abundantly; the direct helper may be best illustrated by reference to some parasitic creature, such as the tape-worm. The tape-worm exists in the human intestines, so that the fewer there are of men the fewer there will be of tape-worms, other things being alike. It is a humiliating reflection, perhaps, that we may be classed as direct helpers to the tape-worm, but the fact is so: we can all see that if there were no men there would be no tape-worms. It is extremely difficult to estimate, in a proper way, the importance and the working of the Conditions of Existence. I do not think there were any of us who had the remotest notion of properly estimating them until the publication of Mr. Darwin's work, which has placed them before us with remarkable clearness; and I must endeavour, as far as I can in my own fashion, to give you some notion of how they work. We shall find it easiest to take a simple case, and one as free as possible from every kind of complication. I will suppose, therefore, that all the habitable part of this globe--the dry land, amounting to about 51,000,000 square miles--I will suppose that the whole of that dry land has the same climate, and that it is composed of the same kind of rock or soil, so that there will be the same station everywhere; we thus get rid of the peculiar influence of different climates and stations. I will then imagine that there shall be but one organic being in the world, and that shall be a plant. In this we start fair. Its food is to be carbonic acid, water and ammonia, and the saline matters in the soil, which are, by the supposition, everywhere alike. We take one single plant, with no opponents, no helpers, and no rivals; it is to be a "fair field, and no favour." Now, I will ask you to imagine further that it shall be a plant which shall produce every year fifty seeds, which is a very moderate number for a plant to produce; and that, by the action of the winds and currents, these seeds shall be equally and gradually distributed over the whole surface of the land. I want you now to trace out what will occur, and you will observe that I am not talking fallaciously any more than a mathematician does when he expounds his problem. If you show that the conditions of your problem are such as may actually occur in Nature and do not transgress any of the known laws of Nature in working out your proposition, then you are as safe in the conclusion you arrive at as is the mathematician in arriving at the solution of his problem. In science, the only way of getting rid of the complications with which a subject of this kind is environed, is to work in this deductive method. What will be the result, then? I will suppose that every plant requires one square foot of ground to live upon; and the result will be that, in the course of nine years, the plant will have occupied every single available spot in the whole globe! I have chalked upon the blackboard the figures by which I arrive at the result:-- Plants. Plants. 1 x 50 in 1st year = 50 50 x 50 " 2nd " = 2,500 2,500 x 50 " 3rd " = 125,000 125,000 x 50 " 4th " = 6,250,000 6,250,000 x 50 " 5th " = 312,500,000 312,500,000 x 50 " 6th " = 15,625,000,000 15,625,000,000 x 50 " 7th " = 781,250,000,000 781,250,000,000 x 50 " 8th " = 39,062,500,000,000 39,062,500,000,000 x 50 " 9th " = 1,953,125,000,000,000 51,000,000 square miles--the ) dry surface of the earth x ) 27,878,400--the number of ) = sq. ft. 1,421,798,400,000,000 sq. ft. in 1 sq. mile ) --------------------- being 531,326,600,000,000 square feet less than would be required at the end of the ninth year. You will see from this that, at the end of the first year the single plant will have produced fifty more of its kind; by the end of the second year these will have increased to 2,500; and so on, in succeeding years, you get beyond even trillions; and I am not at all sure that I could tell you what the proper arithmetical denomination of the total number really is; but, at any rate, you will understand the meaning of all those noughts. Then you see that, at the bottom, I have taken the 51,000,000 of square miles, constituting the surface of the dry land; and as the number of square feet are placed under and subtracted from the number of seeds that would be produced in the ninth year, you can see at once that there would be an immense number more of plants than there would be square feet of ground for their accommodation. This is certainly quite enough to prove my point; that between the eighth and ninth year after being planted the single plant would have stocked the whole available surface of the earth. This is a thing which is hardly conceivable--it seems hardly imaginable--yet it is so. It is indeed simply the law of Malthus exemplified. Mr. Malthus was a clergyman, who worked out this subject most minutely and truthfully some years ago; he showed quite clearly--and although he was much abused for his conclusions at the time, they have never yet been disproved and never will be--he showed that in consequence of the increase in the number of organic beings in a geometrical ratio, while the means of existence cannot be made to increase in the same ratio, that there must come a time when the number of organic beings will be in excess of the power of production of nutriment, and that thus some check must arise to the further increase of those organic beings. At the end of the ninth year we have seen that each plant would not be able to get its full square foot of ground, and at the end of another year it would have to share that space with fifty others the produce of the seeds which it would give off. What, then, takes place? Every plant grows up, flourishes, occupies its square foot of ground, and gives off its fifty seeds; but notice this, that out of this number only one can come to anything; there is thus, as it were, forty-nine chances to one against its growing up; it depends upon the most fortuitous circumstances whether any one of these fifty seeds shall grow up and flourish, or whether it shall die and perish. This is what Mr. Darwin has drawn attention to, and called the "STRUGGLE FOR EXISTENCE"; and I have taken this simple case of a plant because some people imagine that the phrase seems to imply a sort of fight. I have taken this plant and shown you that this is the result of the ratio of the increase, the necessary result of the arrival of a time coming for every species when exactly as many members must be destroyed as are born; that is the inevitable ultimate result of the rate of production. Now, what is the result of all this? I have said that there are forty-nine struggling against every one; and it amounts to this, that the smallest possible start given to any one seed may give it an advantage which will enable it to get ahead of all the others; anything that will enable any one of these seeds to germinate six hours before any of the others will, other things being alike, enable it to choke them out altogether. I have shown you that there is no particular in which plants will not vary from each other; it is quite possible that one of our imaginary plants may vary in such a character as the thickness of the integument of its seeds; it might happen that one of the plants might produce seeds having a thinner integument, and that would enable the seeds of that plant to germinate a little quicker than those of any of the others, and those seeds would most inevitably extinguish the forty-nine times as many that were struggling with them. I have put it in this way, but you see the practical result of the process is the same as if some person had nurtured the one and destroyed the other seeds. It does not matter how the variation is produced, so long as it is once allowed to occur. The variation in the plant once fairly started tends to become hereditary and reproduce itself; the seeds would spread themselves in the same way and take part in the struggle with the forty-nine hundred, or forty-nine thousand, with which they might be exposed. Thus, by degrees, this variety with some slight organic change or modification, must spread itself over the whole surface of the habitable globe, and extirpate or replace the other kinds. That is what is meant by NATURAL SELECTION; that is the kind of argument by which it is perfectly demonstrable that the conditions of existence may play exactly the same part for natural varieties as man does for domesticated varieties. No one doubts at all that particular circumstances may be more favourable for one plant and less so for another, and the moment you admit that, you admit the selective power of nature. Now, although I have been putting a hypothetical case, you must not suppose that I have been reasoning hypothetically. There are plenty of direct experiments which bear out what we may call the theory of natural selection; there is extremely good authority for the statement that if you take the seed of mixed varieties of wheat and sow it, collecting the seed next year and sowing it again, at length you will find that out of all your varieties only two or three have lived, or perhaps even only one. There were one or two varieties which were best fitted to get on, and they have killed out the other kinds in just the same way and with just the same certainty as if you had taken the trouble to remove them. As I have already said, the operation of nature is exactly the same as the artificial operation of man. But if this be true of that simple case, which I put before you, where there is nothing but the rivalry of one member of a species with others, what must be the operation of selective conditions, when you recollect as a matter of fact, that for every species of animal or plant there are fifty or a hundred species which might all, more or less, be comprehended in the same climate, food, and station;--that every plant has multitudinous animals which prey upon it, and which are its direct opponents; and that these have other animals preying upon them,--that every plant has its indirect helpers in the birds that scatter abroad its seed, and the animals that manure it with their dung;--I say, when these things are considered, it seems impossible that any variation which may arise in a species in nature should not tend in some way or other either to be a little better or worse than the previous stock; if it is a little better it will have an advantage over and tend to extirpate the latter in this crush and struggle; and if it is a little worse it will itself be extirpated. I know nothing that more appropriately expresses this, than the phrase, "the struggle for existence "; because it brings before your minds, in a vivid sort of way, some of the simplest possible circumstances connected with it. When a struggle is intense there must be some who are sure to be trodden down, crushed, and overpowered by others; and there will be some who just manage to get through only by the help of the slightest accident. I recollect reading an account of the famous retreat of the French troops, under Napoleon, from Moscow. Worn out, tired, and dejected, they at length came to a great river over which there was but one bridge for the passage of the vast army. Disorganised and demoralised as that army was, the struggle must certainly have been a terrible one--every one heeding only himself, and crushing through the ranks and treading down his fellows. The writer of the narrative, who was himself one of those who were fortunate enough to succeed in getting over, and not among the thousands who were left behind or forced into the river, ascribed his escape to the fact that he saw striding onward through the mass a great strong fellow,--one of the French Cuirassiers, who had on a large blue cloak-and he had enough presence of mind to catch and retain a hold of this strong man's cloak. He says, "I caught hold of his cloak, and although he swore at me and cut at and struck me by turns, and at last, when he found he could not shake me off, fell to entreating me to leave go or I should prevent him from escaping, besides not assisting myself, I still kept tight hold of him, and would not quit my grasp until he had at last dragged me through." Here you see was a case of selective saving--if we may so term it--depending for its success on the strength of the cloth of the Cuirassier's cloak. It is the same in nature; every species has its bridge of Beresina; it has to fight its way through and struggle with other species; and when well-nigh overpowered, it may be that the smallest chance, something in its colour, perhaps--the minutest circumstance--will turn the scale one way or the other. Suppose that by a variation of the black race it had produced the white man at any time--you know that the Negroes are said to believe this to have been the case, and to imagine that Cain was the first white man, and that we are his descendants--suppose that this had ever happened, and that the first residence of this human being was on the West Coast of Africa. There is no great structural difference between the white man and the Negro, and yet there is something so singularly different in the constitution of the two, that the malarias of that country, which do not hurt the black at all, cut off and destroy the white. Then you see there would have been a selective operation performed; if the white man had risen in that way, he would have been selected out and removed by means of the malaria. Now there really is a very curious case of selection of this sort among pigs, and it is a case of selection of colour too. In the woods of Florida there are a great many pigs, and it is a very curious thing that they are all black, every one of them. Professor Wyman was there some years ago, and on noticing no pigs but these black ones, he asked some of the people how it was that they had no white pigs, and the reply was that in the woods of Florida there was a root which they called the Paint Root, and that if the white pigs were to eat any of it, it had the effect of making their hoofs crack, and they died, but if the black pigs ate any of it, it did not hurt them at all. Here was a very simple case of natural selection. A skilful breeder could not more carefully develop the black breed of pigs, and weed out all the white pigs, than the Paint Root does. To show you how remarkably indirect may be such natural selective agencies as I have referred to, I will conclude by noticing a case mentioned by Mr. Darwin, and which is certainly one of the most curious of its kind. It is that of the Humble Bee. It has been noticed that there are a great many more humble bees in the neighbourhood of towns, than out in the open country; and the explanation of the matter is this: the humble bees build nests, in which they store their honey and deposit the larvæ and eggs. The field mice are amazingly fond of the honey and larvæ; therefore, wherever there are plenty of field mice, as in the country, the humble bees are kept down; but in the neighbourhood of towns, the number of cats which prowl about the fields eat up the field mice, and of course the more mice they eat up the less there are to prey upon the larvæ of the bees--the cats are therefore the INDIRECT HELPERS of the bees. [Footnote: The humble bees, on the other hand, are direct helpers of some plants, such as the heartsease and red clover, which are fertilised by the visits of the bees; and they are indirect helpers of the numerous insects which are more or less completely supported by the heartsease and red clover.] Coming back a step farther we may say that the old maids are also indirect friends of the humble bees, and indirect enemies of the field mice, as they keep the cats which eat up the latter! This is an illustration somewhat beneath the dignity of the subject, perhaps, but it occurs to me in passing, and with it I will conclude this lecture. VI. A CRITICAL EXAMINATION OF THE POSITION OF MR. DARWIN'S WORK, "ON THE ORIGIN OF SPECIES," IN RELATION TO THE COMPLETE THEORY OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE In the preceding five lectures I have endeavoured to give you an account of those facts, and of those reasonings from facts, which form the data upon which all theories regarding the causes of the phenomena of organic nature must be based. And, although I have had frequent occasion to quote Mr. Darwin--as all persons hereafter, in speaking upon these subjects, will have occasion to quote his famous book on the "Origin of Species,"--you must yet remember that, wherever I have quoted him, it has not been upon theoretical points, or for statements in any way connected with his particular speculations, but on matters of fact, brought forward by himself, or collected by himself, and which appear incidentally in his book. If a man _will_ make a book, professing to discuss a single question, an encyclopædia, I cannot help it. Now, having had an opportunity of considering in this sort of way the different statements bearing upon all theories whatsoever, I have to lay before you, as fairly as I can, what is Mr. Darwin's view of the matter and what position his theories hold, when judged by the principles which I have previously laid down, as deciding our judgments upon all theories and hypotheses. I have already stated to you that the inquiry respecting the causes of the phenomena of organic nature resolves itself into two problems--the first being the question of the origination of living or organic beings; and the second being the totally distinct problem of the modification and perpetuation of organic beings when they have already come into existence. The first question Mr. Darwin does not touch; he does not deal with it at all; but he says:--"Given the origin of organic matter--supposing its creation to have already taken place, my object is to show in consequence of what laws and what demonstrable properties of organic matter, and of its environments, such states of organic nature as those with which we are acquainted must have come about." This, you will observe, is a perfectly legitimate proposition; every person has a right to define the limits of the inquiry which he sets before himself; and yet it is a most singular thing that in all the multifarious, and, not unfrequently, ignorant attacks which have been made upon the "Origin of Species," there is nothing which has been more speciously criticised than this particular limitation. If people have nothing else to urge against the book, they say--"Well, after all, you see Mr. Darwin's explanation of the 'Origin of Species' is not good for much, because, in the long run, he admits that he does not know how organic matter began to exist. But if you admit any special creation for the first particle of organic matter you may just as well admit it for all the rest; five hundred or five thousand distinct creations are just as intelligible, and just as little difficult to understand, as one." The answer to these cavils is two-fold. In the first place, all human inquiry must stop somewhere; all our knowledge and all our investigation cannot take us beyond the limits set by the finite and restricted character of our faculties, or destroy the endless unknown, which accompanies, like its shadow, the endless procession of phenomena. So far as I can venture to offer an opinion on such a matter, the purpose of our being in existence, the highest object that human beings can set before themselves, is not the pursuit of any such chimera as the annihilation of the unknown; but it is simply the unwearied endeavour to remove its boundaries a little further from our little sphere of action. I wonder if any historian would for a moment admit the objection, that it is preposterous to trouble ourselves about the history of the Roman Empire, because we do not know anything positive about the origin and first building of the city of Rome! Would it be a fair objection to urge, respecting the sublime discoveries of a Newton, or a Kepler, those great philosophers, whose discoveries have been of the profoundest benefit and service to all men--to say to them--"After all that you have told us as to how the planets revolve, and how they are maintained in their orbits, you cannot tell us what is the cause of the origin of the sun, moon, and stars. So what is the use of what you have done?" Yet these objections would not be one whit more preposterous than the objections which have been made to the "Origin of Species." Mr. Darwin, then, had a perfect right to limit his inquiry as he pleased, and the only question for us--the inquiry being so limited--is to ascertain whether the method of his inquiry is sound or unsound; whether he has obeyed the canons which must guide and govern all investigation, or whether he has broken them; and it was because our inquiry this evening is essentially limited to that question, that I spent a good deal of time in a former lecture (which, perhaps some of you thought might have been better employed), in endeavouring to illustrate the method and nature of scientific inquiry in general. We shall now have to put in practice the principles that I then laid down. I stated to you in substance, if not in words, that wherever there are complex masses of phenomena to be inquired into, whether they be phenomena of the affairs of daily life, or whether they belong to the more abstruse and difficult problems laid before the philosopher, our course of proceeding in unravelling that complex chain of phenomena with a view to get at its cause, is always the same; in all cases we must invent an hypothesis; we must place before ourselves some more or less likely supposition respecting that cause; and then, having assumed an hypothesis, having supposed a cause for the phenomena in question, we must endeavour, on the one hand, to demonstrate our hypothesis, or, on the other, to upset and reject it altogether, by testing it in three ways. We must, in the first place, be prepared to prove that the supposed causes of the phenomena exist in nature; that they are what the logicians call _vera causæ_--true causes;--in the next place, we should be prepared to show that the assumed causes of the phenomena are competent to produce such phenomena as those which we wish to explain by them; and in the last place, we ought to be able to show that no other known causes are competent to produce these phenomena. If we can succeed in satisfying these three conditions we shall have demonstrated our hypothesis; or rather I ought to say we shall have proved it as far as certainty is possible for us; for, after all, there is no one of our surest convictions which may not be upset, or at any rate modified by a further accession of knowledge. It was because it satisfied these conditions that we accepted the hypothesis as to the disappearance of the tea-pot and spoons in the case I supposed in a previous lecture; we found that our hypothesis on that subject was tenable and valid, because the supposed cause existed in nature, because it was competent to account for the phenomena, and because no other known cause was competent to account for them; and it is upon similar grounds that any hypothesis you choose to name is accepted in science as tenable and valid. What is Mr. Darwin's hypothesis? As I apprehend it--for I have put it into a shape more convenient for common purposes than I could find _verbatim_ in his book--as I apprehend it, I say, it is, that all the phenomena of organic nature, past and present, result from, or are caused by, the inter-action of those properties of organic matter, which we have called ATAVISM and VARIABILITY, with the CONDITIONS OF EXISTENCE, or, in other words,--given the existence of organic matter, its tendency to transmit its properties, and its tendency occasionally to vary; and, lastly, given the conditions of existence by which organic matter is surrounded--that these put together are the causes of the Present and of the Past conditions of ORGANIC NATURE. Such is the hypothesis as I understand it. Now let us see how it will stand the various tests which I laid down just now. In the first place, do these supposed causes of the phenomena exist in nature? Is it the fact that, in nature, these properties of organic matter--atavism and variability--and those phenomena which we have called the conditions of existence,--is it true that they exist? Well, of course, if they do not exist, all that I have told you in the last three or four lectures must be incorrect, because I have been attempting to prove that they do exist, and I take it that there is abundant evidence that they do exist; so far, therefore, the hypothesis does not break down. But in the next place comes a much more difficult inquiry:--Are the causes indicated competent to give rise to the phenomena of organic nature? I suspect that this is indubitable to a certain extent. It is demonstrable, I think, as I have endeavoured to show you, that they are perfectly competent to give rise to all the phenomena which are exhibited by RACES in nature. Furthermore, I believe that they are quite competent to account for all that we may call purely structural phenomena which are exhibited by SPECIES in nature. On that point also I have already enlarged somewhat. Again, I think that the causes assumed are competent to account for most of the physiological characteristics of species, and I not only think that they are competent to account for them, but I think that they account for many things which otherwise remain wholly unaccountable and inexplicable, and I may say incomprehensible. For a full exposition of the grounds on which this conviction is based, I must refer you to Mr. Darwin's work; all that I can do now is to illustrate what I have said by two or three cases taken almost at random. I drew your attention, on a previous evening, to the facts which are embodied in our systems of Classification, which are the results of the examination and comparison of the different members of the animal kingdom one with another. I mentioned that the whole of the animal kingdom is divisible into five sub-kingdoms; that each of these sub-kingdoms is again divisible into provinces; that each province may be divided into classes, and the classes into the successively smaller groups, orders, families, genera, and species. Now, in each of these groups the resemblance in structure among the members of the group is closer in proportion as the group is smaller. Thus, a man and a worm are members of the animal kingdom in virtue of certain apparently slight though really fundamental resemblances which they present. But a man and a fish are members of the same sub-kingdom _Vertebrata_, because they are much more like one another than either of them is to a worm, or a snail, or any member of the other sub-kingdoms. For similar reasons men and horses are arranged as members of the same Class, _Mammalia_; men and apes as members of the same Order, _Primates_; and if there were any animals more like men than they were like any of the apes, and yet different from men in important and constant particulars of their organisation, we should rank them as members of the same Family, or of the same Genus, but as of distinct Species. That it is possible to arrange all the varied forms of animals into groups, having this sort of singular subordination one to the other, is a very remarkable circumstance; but, as Mr. Darwin remarks, this is a result which is quite to be expected, if the principles which he lays down be correct. Take the case of the races which are known to be produced by the operation of atavism and variability, and the conditions of existence which check and modify these tendencies. Take the case of the pigeons that I brought before you: there it was shown that they might be all classed as belonging to some one of five principal divisions, and that within these divisions other subordinate groups might be formed. The members of these groups are related to one another in just the same way as the genera of a family, and the groups themselves as the families of an order, or the orders of a class; while all have the same sort of structural relations with the wild rock-pigeon, as the members of any great natural group have with a real or imaginary typical form. Now, we know that all varieties of pigeons of every kind have arisen by a process of selective breeding from a common stock, the rock-pigeon; hence, you see, that if all species of animals have proceeded from some common stock, the general character of their structural relations, and of our systems of classification, which express those relations, would be just what we find them to be. In other words, the hypothetical cause is, so far, competent to produce effects similar to those of the real cause. Take, again, another set of very remarkable facts,--the existence of what are called rudimentary organs, organs for which we can find no obvious use, in the particular animal economy in which they are found, and yet which are there. Such are the splint-like bones in the leg of the horse, which I here show you, and which correspond with bones which belong to certain toes and fingers in the human hand and foot. In the horse you see they are quite rudimentary, and bear neither toes nor fingers; so that the horse has only one "finger" in his fore-foot and one "toe" in his hind-foot. But it is a very curious thing that the animals closely allied to the horse show more toes than he; as the rhinoceros, for instance: he has these extra toes well formed, and anatomical facts show very clearly that he is very closely related to the horse indeed. So we may say that animals, in an anatomical sense nearly related to the horse, have those parts which are rudimentary in him fully developed. Again, the sheep and the cow have no cutting-teeth, but only a hard pad in the upper jaw. That is the common characteristic of ruminants in general. But the calf has in its upper jaw some rudiments of teeth which never are developed, and never play the part of teeth at all. Well, if you go back in time, you find some of the older, now extinct, allies of the ruminants have well-developed teeth in their upper jaws; and at the present day the pig (which is in structure closely connected with ruminants) has well-developed teeth in its upper jaw; so that here is another instance of organs well-developed and very useful, in one animal, represented by rudimentary organs, for which we can discover no purpose whatsoever in another closely allied animal. The whalebone whale, again, has horny "whalebone" plates in its mouth, and no teeth; but the young foetal whale before it is born has teeth in its jaws; they, however, are never used, and they never come to anything. But other members of the group to which the whale belongs have well-developed teeth in both jaws. Upon any hypothesis of special creation, facts of this kind appear to me to be entirely unaccountable and inexplicable, but they cease to be so if you accept Mr. Darwin's hypothesis, and see reason for believing that the whalebone whale and the whale with teeth in its mouth both sprang from a whale that had teeth, and that the teeth of the foetal whale are merely remnants--recollections, if we may so say--of the extinct whale. So in the case of the horse and the rhinoceros: suppose that both have descended by modification from some earlier form which had the normal number of toes, and the persistence of the rudimentary bones which no longer support toes in the horse becomes comprehensible. In the language that we speak in England, and in the language of the Greeks, there are identical verbal roots, or elements entering into the composition of words. That fact remains unintelligible so long as we suppose English and Greek to be independently created tongues; but when it is shown that both languages are descended from one original, we give an explanation of that resemblance. In the same way the existence of identical structural roots, if I may so term them, entering into the composition of widely different animals, is striking evidence in favour of the descent of those animals from a common original. To turn to another kind of illustration:--If you regard the whole series of stratified rocks--that enormous thickness of sixty or seventy thousand feet that I have mentioned before, constituting the only record we have of a most prodigious lapse of time, that time being, in all probability, but a fraction of that of which we have no record;--if you observe in these successive strata of rocks successive groups of animals arising and dying out, a constant succession, giving you the same kind of impression, as you travel from one group of strata to another, as you would have in travelling from one country to another;--when you find this constant succession of forms, their traces obliterated except to the man of science--when you look at this wonderful history, and ask what it means, it is only a paltering with words if you are offered the reply--"They were so created." But if, on the other hand, you look on all forms of organised beings as the results of the gradual modification of a primitive type, the facts receive a meaning, and you see that these older conditions are the necessary predecessors of the present. Viewed in this light the facts of palaeontology receive a meaning--upon any other hypothesis I am unable to see, in the slightest degree, what knowledge or signification we are to draw out of them. Again, note as bearing upon the same point, the singular likeness which obtains between the successive Faunæ and Floræ, whose remains are preserved on the rocks: you never find any great and enormous difference between the immediately successive Faunæ and Floræ, unless you have reason to believe there has also been a great lapse of time or a great change of conditions. The animals, for instance, of the newest tertiary rocks, in any part of the world, are always, and without exception, found to be closely allied with those which now live in that part of the world. For example, in Europe, Asia, and Africa, the large mammals are at present rhinoceroses, hippopotamuses, elephants, lions, tigers, oxen, horses, &c.; and if you examine the newest tertiary deposits, which contain the animals and plants which immediately preceded those which now exist in the same country, you do not find gigantic specimens of ant-eaters and kangaroos, but you find rhinoceroses, elephants, lions, tigers, &c.,--of different species to those now living--but still their close allies. If you turn to South America, where, at the present day, we have great sloths and armadilloes and creatures of that kind, what do you find in the newest tertiaries? You find the great sloth-like creature, the _Megatherium_, and the great armadillo, the _Glyptodon_, and so on. And if you go to Australia you find the same law holds good, namely, that that condition of organic nature which has preceded the one which now exists, presents differences perhaps of species, and of genera, but that the great types of organic structure are the same as those which now flourish. What meaning has this fact upon any other hypothesis or supposition than one of successive modification? But if the population of the world, in any age, is the result of the gradual modification of the forms which peopled it in the preceding age--if that has been the case, it is intelligible enough; because we may expect that the creature that results from the modification of an elephantine mammal shall be something like an elephant, and the creature which is produced by the modification of an armadillo-like mammal shall be like an armadillo. Upon that supposition, I say, the facts are intelligible; upon any other, that I am aware of, they are not. So far, the facts of palæontology are consistent with almost any form of the doctrine of progressive modification; they would not be absolutely inconsistent with the wild speculations of De Maillet, or with the less objectionable hypothesis of Lamarck. But Mr. Darwin's views have one peculiar merit; and that is, that they are perfectly consistent with an array of facts which are utterly inconsistent with, and fatal to, any other hypothesis of progressive modification which has yet been advanced. It is one remarkable peculiarity of Mr. Darwin's hypothesis that it involves no necessary progression or incessant modification, and that it is perfectly consistent with the persistence for any length of time of a given primitive stock, contemporaneously with its modifications. To return to the case of the domestic breeds of pigeons, for example; you have the dove-cot pigeon, which closely resembles the rock pigeon, from which they all started, existing at the same time with the others. And if species are developed in the same way in nature, a primitive stock and its modifications may, occasionally, all find the conditions fitted for their existence; and though they come into competition, to a certain extent, with one another, the derivative species may not necessarily extirpate the primitive one, or _vice versa_. Now palæontology shows us many facts which are perfectly harmonious with these observed effects of the process by which Mr. Darwin supposes species to have originated, but which appear to me to be totally inconsistent with any other hypothesis which has been proposed. There are some groups of animals and plants, in the fossil world, which have been said to belong to "persistent types," because they have persisted, with very little change indeed, through a very great range of time, while everything about them has changed largely. There are families of fishes whose type of construction has persisted all the way from the carboniferous strata right up to the cretaceous; and others which have lasted through almost the whole range of the secondary rocks, and from the lias to the older tertiaries. It is something stupendous this--to consider a genus lasting without essential modifications through all this enormous lapse of time while almost everything else was changed and modified. Thus I have no doubt that Mr. Darwin's hypothesis will be found competent to explain the majority of the phenomena exhibited by species in nature; but in an earlier lecture I spoke cautiously with respect to its power of explaining all the physiological peculiarities of species. There is, in fact, one set of these peculiarities which the theory of selective modification, as it stands at present, is not wholly competent to explain, and that is the group of phenomena which I mentioned to you under the name of Hybridism, and which I explained to consist in the sterility of the offspring of certain species when crossed one with another. It matters not one whit whether this sterility is universal, or whether it exists only in a single case. Every hypothesis is bound to explain, or, at any rate, not be inconsistent with, the whole of the facts which it professes to account for; and if there is a single one of these facts which can be shown to be inconsistent with (I do not merely mean inexplicable by, but contrary to) the hypothesis, the hypothesis falls to the ground,--it is worth nothing. One fact with which it is positively inconsistent is worth as much, and as powerful in negativing the hypothesis, as five hundred. If I am right in thus defining the obligations of an hypothesis, Mr. Darwin, in order to place his views beyond the reach of all possible assault, ought to be able to demonstrate the possibility of developing from a particular stock by selective breeding, two forms, which should either be unable to cross one with another, or whose cross-bred offspring should be infertile with one another. For, you see, if you have not done that you have not strictly fulfilled all the conditions of the problem; you have not shown that you can produce, by the cause assumed, all the phenomena which you have in nature. Here are the phenomena of Hybridism staring you in the face, and you cannot say, "I can, by selective modification, produce these same results." Now, it is admitted on all hands that, at present, so far as experiments have gone, it has not been found possible to produce this complete physiological divergence by selective breeding. I stated this very clearly before, and I now refer to the point, because, if it could be proved, not only that this _has_ not been done, but that it _cannot_ be done; if it could be demonstrated that it is impossible to breed selectively, from any stock, a form which shall not breed with another, produced from the same stock; and if we were shown that this must be the necessary and inevitable results of all experiments, I hold that Mr. Darwin's hypothesis would be utterly shattered. But has this been done? or what is really the state of the case? It is simply that, so far as we have gone yet with our breeding, we have not produced from a common stock two breeds which are not more or less fertile with one another. I do not know that there is a single fact which would justify any one in saying that any degree of sterility has been observed between breeds absolutely known to have been produced by selective breeding from a common stock. On the other hand, I do not know that there is a single fact which can justify any one in asserting that such sterility cannot be produced by proper experimentation. For my own part, I see every reason to believe that it may, and will be so produced. For, as Mr. Darwin has very properly urged, when we consider the phenomena of sterility, we find they are most capricious; we do not know what it is that the sterility depends on. There are some animals which will not breed in captivity; whether it arises from the simple fact of their being shut up and deprived of their liberty, or not, we do not know, but they certainly will not breed. What an astounding thing this is, to find one of the most important of all functions annihilated by mere imprisonment! So, again, there are cases known of animals which have been thought by naturalists to be undoubted species, which have yielded perfectly fertile hybrids; while there are other species which present what everybody believes to be varieties [Footnote: And as I conceive with very good reason; but if any objector urges that we cannot prove that they have been produced by artificial or natural selection, the objection must be admitted--ultra-sceptical as it is. But in science, scepticism is a duty.] which are more or less infertile with one another. There are other cases which are truly extraordinary; there is one, for example, which has been carefully examined,--of two kinds of sea-weed, of which the male element of the one, which we may call A, fertilises the female element of the other, B; while the male element of B will not fertilise the female element of A; so that, while the former experiment seems to show us that they are _varieties_, the latter leads to the conviction that they are _species_. When we see how capricious and uncertain this sterility is, how unknown the conditions on which it depends, I say that we have no right to affirm that those conditions will not be better understood by and by, and we have no ground for supposing that we may not be able to experiment so as to obtain that crucial result which I mentioned just now. So that though Mr. Darwin's hypothesis does not completely extricate us from this difficulty at present, we have not the least right to say it will not do so. There is a wide gulf between the thing you cannot explain and the thing that upsets you altogether. There is hardly any hypothesis in this world which has not some fact in connection with it which has not been explained, but that is a very different affair to a fact that entirely opposes your hypothesis; in this case all you can say is, that your hypothesis is in the same position as a good many others. Now, as to the third test, that there are no other causes competent to explain the phenomena, I explained to you that one should be able to say of an hypothesis, that no other known causes than those supposed by it are competent to give rise to the phenomena. Here, I think, Mr. Darwin's view is pretty strong. I really believe that the alternative is either Darwinism or nothing, for I do not know of any rational conception or theory of the organic universe which has any scientific position at all beside Mr. Darwin's. I do not know of any proposition that has been put before us with the intention of explaining the phenomena of organic nature, which has in its favour a thousandth part of the evidence which may be adduced in favour of Mr. Darwin's views. Whatever may be the objections to his views, certainly all other theories are absolutely out of court. Take the Lamarckian hypothesis, for example. Lamarck was a great naturalist, and to a certain extent went the right way to work; he argued from what was undoubtedly a true cause of some of the phenomena of organic nature. He said it is a matter of experience that an animal may be modified more or less in consequence of its desires and consequent actions. Thus, if a man exercise himself as a blacksmith, his arms will become strong and muscular; such organic modification is a result of this particular action and exercise. Lamarck thought that by a very simple supposition based on this truth he could explain the origin of the various animal species: he said, for example, that the short-legged birds which live on fish had been converted into the long-legged waders by desiring to get the fish without wetting their feathers, and so stretching their legs more and more through successive generations. If Lamarck could have shown experimentally that even races of animals could be produced in this way, there might have been some ground for his speculations. But he could show nothing of the kind, and his hypothesis has pretty well dropped into oblivion, as it deserved to do. I said in an earlier lecture that there are hypotheses and hypotheses, and when people tell you that Mr. Darwin's strongly-based hypothesis is nothing but a mere modification of Lamarck's, you will know what to think of their capacity for forming a judgment on this subject. But you must recollect that when I say I think it is either Mr. Darwin's hypothesis or nothing; that either we must take his view, or look upon the whole of organic nature as an enigma, the meaning of which is wholly hidden from us; you must understand that I mean that I accept it provisionally, in exactly the same way as I accept any other hypothesis. Men of science do not pledge themselves to creeds; they are bound by articles of no sort; there is not a single belief that it is not a bounden duty with them to hold with a light hand and to part with cheerfully, the moment it is really proved to be contrary to any fact, great or small. And if, in course of time I see good reasons for such a proceeding, I shall have no hesitation in coming before you, and pointing out any change in my opinion without finding the slightest occasion to blush for so doing. So I say that we accept this view as we accept any other, so long as it will help us, and we feel bound to retain it only so long as it will serve our great purpose--the improvement of Man's estate and the widening of his knowledge. The moment this, or any other conception, ceases to be useful for these purposes, away with it to the four winds; we care not what becomes of it! But to say truth, although it has been my business to attend closely to the controversies roused by the publication of Mr. Darwin's book, I think that not one of the enormous mass of objections and obstacles which have been raised is of any very great value, except that sterility case which I brought before you just now. All the rest are misunderstandings of some sort, arising either from prejudice, or want of knowledge, or still more from want of patience and care in reading the work. For you must recollect that it is not a book to be read with as much ease as its pleasant style may lead you to imagine. You spin through it as if it were a novel the first time you read it, and think you know all about it; the second time you read it you think you know rather less about it; and the third time, you are amazed to find how little you have really apprehended its vast scope and objects. I can positively say that I never take it up without finding in it some new view, or light, or suggestion that I have not noticed before. That is the best characteristic of a thorough and profound book; and I believe this feature of the "Origin of Species" explains why so many persons have ventured to pass judgment and criticisms upon it which are by no means worth the paper they are written on. Before concluding these lectures there is one point to which I must advert--though, as Mr. Darwin has said nothing about man in his book, it concerns myself rather than him;--for I have strongly maintained on sundry occasions that if Mr. Darwin's views are sound, they apply as much to man as to the lower mammals, seeing that it is perfectly demonstrable that the structural differences which separate man from the apes are not greater than those which separate some apes from others. There cannot be the slightest doubt in the world that the argument which applies to the improvement of the horse from an earlier stock, or of ape from ape, applies to the improvement of man from some simpler and lower stock than man. There is not a single faculty--functional or structural, moral, intellectual, or instinctive, there--is no faculty whatever that is not capable of improvement; there is no faculty whatsoever which does not depend upon structure, and as structure tends to vary, it is capable of being improved. Well, I have taken a good deal of pains at various times to prove this, and I have endeavoured to meet the objections of those who maintain, that the structural differences between man and the lower animals are of so vast a character and enormous extent, that even if Mr. Darwin's views are correct, you cannot imagine this particular modification to take place. It is, in fact, an easy matter to prove that, so far as structure is concerned, man differs to no greater extent from the animals which are immediately below him than these do from other members of the same order. Upon the other hand, there is no one who estimates more highly than I do the dignity of human nature, and the width of the gulf in intellectual and moral matters which lies between man and the whole of the lower creation. But I find this very argument brought forward vehemently by some. "You say that man has proceeded from a modification of some lower animal, and you take pains to prove that the structural differences which are said to exist in his brain do not exist at all, and you teach that all functions, intellectual, moral, and others, are the expression or the result, in the long run, of structures, and of the molecular forces which they exert." It is quite true that I do so. "Well, but," I am told at once, somewhat triumphantly, "you say in the same breath that there is a great moral and intellectual chasm between man and the lower animals. How is this possible when you declare that moral and intellectual characteristics depend on structure, and yet tell us that there is no such gulf between the structure of man and that of the lower animals?" I think that objection is based upon a misconception of the real relations which exist between structure and function, between mechanism and work. Function is the expression of molecular forces and arrangements no doubt; but, does it follow from this, that variation in function so depends upon variation in structure that the former is always exactly proportioned to the latter? If there is no such relation, if the variation in function which follows on a variation in structure may be enormously greater than the variation of the structure, then, you see, the objection falls to the ground. Take a couple of watches--made by the same maker, and as completely alike as possible; set them upon the table, and the function of each--which is its rate of going--will be performed in the same manner, and you shall be able to distinguish no difference between them; but let me take a pair of pincers, and if my hand is steady enough to do it, let me just lightly crush together the bearings of the balance-wheel, or force to a slightly different angle the teeth of the escapement of one of them, and of course you know the immediate result will be that the watch, so treated, from that moment will cease to go. But what proportion is there between the structural alteration and the functional result? Is it not perfectly obvious that the alteration is of the minutest kind, yet that, slight as it is, it has produced an infinite difference in the performance of the functions of these two instruments? Well, now, apply that to the present question. What is it that constitutes and makes man what he is? What is it but his power of language--that language giving him the means of recording his experience--making every generation somewhat wiser than its predecessor--more in accordance with the established order of the universe? What is it but this power of speech, of recording experience, which enables men to be men--looking before and after and, in some dim sense, understanding the working of this wondrous universe--and which distinguishes man from the whole of the brute world? I say that this functional difference is vast, unfathomable, and truly infinite in its consequences; and I say at the same time, that it may depend upon structural differences which shall be absolutely inappreciable to us with our present means of investigation. What is this very speech that we are talking about? I am speaking to you at this moment, but if you were to alter, in the minutest degree, the proportion of the nervous forces now active in the two nerves which supply the muscles of my glottis, I should become suddenly dumb. The voice is produced only so long as the vocal chords are parallel; and these are parallel only so long as certain muscles contract with exact equality; and that again depends on the equality of action of those two nerves I spoke of. So that a change of the minutest kind in the structure of one of these nerves, or in the structure of the part in which it originates, or of the supply of blood to that part, or of one of the muscles to which it is distributed, might render all of us dumb. But a race of dumb men, deprived of all communication with those who could speak, would be little indeed removed from the brutes. And the moral and intellectual difference between them and ourselves would be practically infinite, though the naturalist should not be able to find a single shadow of even specific structural difference. But let me dismiss this question now, and, in conclusion, let me say that you may go away with it as my mature conviction, that Mr. Darwin's work is the greatest contribution which has been made to biological science since the publication of the "Regne Animal" of Cuvier, and since that of the "History of Development," of Von Baer. I believe that if you strip it of its theoretical part it still remains one of the greatest encyclopaedias of biological doctrine that any one man ever brought forth; and I believe that, if you take it as the embodiment of an hypothesis, it is destined to be the guide of biological and psychological speculation for the next three or four generations. END OF VOL. II 
6335	----	THE GEOLOGICAL EVIDENCE OF THE ANTIQUITY OF MAN By Sir Charles Lyell, BT., F.R.S., Etc. London: Published By J.M. Dent & Sons Ltd. And In New York By E.P. Dutton & Co. With Introduction And Notes By R.H. Rastall, M.A., F.G.S. EVERYMAN I WILL GO WITH THEE & BE THY GUIDE IN THY MOST NEED TO GO BY THY SIDE. EVERYMAN'S LIBRARY EDITED BY ERNEST RHYS. SCIENCE. HOC SOLUM SCIO QUOD NIHIL SCIO. INTRODUCTION. The "Antiquity of Man" was published in 1863, and ran into a third edition in the course of that year. The cause of this is not far to seek. Darwin's "Origin of Species" appeared in 1859, only four years earlier, and rapidly had its effect in drawing attention to the great problem of the origin of living beings. The theories of Darwin and Wallace brought to a head and presented in a concrete shape the somewhat vague speculations as to development and evolution which had long been floating in the minds of naturalists. In the actual working out of Darwin's great theory it is impossible to overestimate the influence of Lyell. This is made abundantly clear in Darwin's letters, and it must never be forgotten that Darwin himself was a geologist. His training in this science enabled him to grasp the import of the facts so ably marshalled by Lyell in the "Principles of Geology," a work which, as Professor Judd has clearly shown,* contributed greatly to the advancement of evolutionary theory in general. (* Judd "The Coming of Evolution" ("Cambridge Manuals of Science and Literature") Cambridge 1910 chapters 6 and 7.) From a study of the evolution of plants and of the lower animals it was an easy and obvious transition to man, and this step was soon taken. Since in his physical structure man shows so close a resemblance to the higher animals it was a natural conclusion that the laws governing the development of the one should apply also to the other, in spite of preconceived opinions derived from authority. Unfortunately the times were then hardly ripe for a calm and logical treatment of this question: prejudice in many cases took the place of argument, and the result was too often an undignified squabble instead of a scientific discussion. However, the dogmatism was not by any means all on one side. The disciples as usual went farther than the master, and their teaching when pushed to extremities resulted in a peculiarly dreary kind of materialism, a mental attitude which still survives to a certain extent among scientific and pseudo-scientific men of the old school. In more Recent times this dogmatic agnosticism of the middle Victorian period has been gradually replaced by speculations of a more positive type, such as those of the Mendelian school in biology and the doctrines of Bergson on the philosophical side. With these later developments we are not here concerned. In dealing with the evolution and history of man as with that of any other animal, the first step is undoubtedly to collect the facts, and this is precisely what Lyell set out to do in the "Antiquity of Man." The first nineteen chapters of the book are purely an empirical statement of the evidence then available as to the existence of man in pre-historic times: the rest of the book is devoted to a consideration of the connection between the facts previously stated and Darwin's theory of the origin of species by variation and natural selection. The keynote of Lyell's work, throughout his life, was observation. Lyell was no cabinet geologist; he went to nature and studied phenomena at first hand. Possessed of abundant leisure and ample means he travelled far and wide, patiently collecting material and building up the modern science of physical geology, whose foundations had been laid by Hutton and Playfair. From the facts thus collected he drew his inferences, and if later researches showed these inferences to be wrong, unlike some of his contemporaries, he never hesitated to say so. Thus and thus only is true progress in science attained. Lyell is universally recognised as the leader of the Uniformitarian school of geologists, and it will be well to consider briefly what is implied in this term. The principles of Uniformitarianism may be summed up thus: THE PRESENT IS THE KEY TO THE PAST. That is to say, the processes which have gone on in the past were the same in general character as those now seen in operation, though probably differing in degree. This theory is in direct opposition to the ideas of the CATASTROPHIC school, which were dominant at the beginning of the nineteenth century. The catastrophists attributed all past changes to sudden and violent convulsions of nature, by which all living beings were destroyed, to be replaced by a fresh creation. At least such were the tenets of the extremists. In opposition to these views the school of Hutton and Lyell introduced the principle of continuity and development. There is no discrepancy between Uniformitarianism and evolution. The idea of Uniformitarianism does not imply that things have always been the same; only that they were similar, and between these two terms there is a wide distinction. Evolution of any kind whatever naturally implies continuity, and this is the fundamental idea of Lyellian geology. In spite, however, of this clear and definite conception of natural and organic evolution, in all those parts of his works dealing with earth-history, with the stratified rocks and with the organisms entombed in them, Lyell adopted a plan which has now been universally abandoned. He began with the most Recent formations and worked backwards from the known to the unknown. To modern readers this is perhaps the greatest drawback to his work, since it renders difficult the study of events in their actual sequence. However, it must be admitted that, taking into account the state of geological knowledge before his time, this course was almost inevitable. The succession of the later rocks was fairly well known, thanks to the labours of William Smith and others, but in the lower part of the sequence of stratified rocks there were many gaps, and more important still, there was no definite base. Although this want of a starting point has been largely supplied by the labours of Sedgwick, Murchison, De la Beche, Ramsay, and a host of followers, still considerable doubt prevails as to which constitutes the oldest truly stratified series, and the difficulty has only been partially circumvented by the adoption of an arbitrary base-line, from which the succession is worked out both upwards and downwards. So the problem is only removed a stage further back. In the study of human origins a similar difficulty is felt with special acuteness; the beginnings must of necessity be vague and uncertain, and the farther back we go the fainter will naturally be the traces of human handiwork and the more primitive and doubtful those traces when discovered. The reprinting of the "Antiquity of Man" is particularly appropriate at the present time, owing to the increased attention drawn to the subject by recent discoveries. Ever since the publication of the "Origin of Species" and the discussions that resulted from that publication, the popular imagination has been much exercised by the possible existence of forms intermediate between the apes and man; the so-called "Missing Link." Much has been written on this subject, some of it well-founded and some very much the reverse. The discovery of the Neanderthal skull is fully described in this volume, and this skull is certainly of a low type, but it is more human than ape-like. The same remark applies still more strongly to the Engis skull, the man of Spy, the recently discovered Sussex skull, and other well-known examples of early human remains. The Pithecanthropus of Java alone shows perhaps more affinity to the apes. The whole subject has been most ably discussed by Professor Sollas in his recent book entitled "Ancient Hunters." The study of Palaeolithic flint implements has been raised to a fine art. Both in England and France a regular succession of primitive types has been established and correlated with the gravel terraces of existing rivers, and even with the deposits of rivers no longer existing and with certain glacial deposits. But with all of these the actual bodily remains of man are comparatively scanty. From this it may be concluded that primitive methods of burial were such as to be unfavourable to the actual preservation of human remains. Attempts have also been made to prove the existence of man in pre-glacial times, but hitherto none of these have met with general acceptance, since in no case is the evidence beyond doubt. One of the most important results of recent research in the subject has been the establishment of the existence of man in interglacial times. When Lyell wrote, it was not fully recognised that the glaciation of Europe was not one continuous process, but that it could be divided into several episodes, glaciations, or advances of the ice, separated by a warm interglacial period. The monumental researches of Penck and Bruckner in the Alps have there established four glaciations with mild interglacial periods, but all of these cannot be clearly traced in Britain. One very important point also is the recognition of the affinities of certain types of Palaeolithic man to the Eskimo, the Australians, and the Bushmen of South Africa. However, it is impossible to give here a review of the whole subject. Full details of recent researches will be found in the works mentioned in the notes at the end of the book. Another point of great interest and importance, arising directly from the study of early man is the nature of the events constituting the glacial period in Britain and elsewhere. This has been for many years a fertile subject of controversy, and is likely to continue such. Lyell, in common with most of the geologists of his day, assumes that during the glacial period the British Isles were submerged under the sea to a depth of many hundreds of feet, at any rate as regards the region north of a line drawn from London to Bristol. Later authors, however, explained the observed phenomena on the hypothesis of a vast ice-sheet of the Greenland type, descending from the mountains of Scotland and Scandinavia, filling up the North Sea and spreading over eastern England. This explanation is now accepted by the majority, but it must be recognised that it involves enormous mechanical difficulties. It is impossible to pursue the subject here; for a full discussion reference may be made to Professor Bonney's presidential address to the British Association at Sheffield in 1910. It will be seen, therefore, that the "Antiquity of Man" opens up a wide field of speculation into a variety of difficult and obscure though interesting subjects. In the light of modern research it would be an easy task to pile up a mountain of criticism on points of detail. But, though easy, it would be a thankless task. It is scarcely too much to say that the dominant impression of most readers after perusing this book will be one of astonishment and admiration at the insight and breadth of view displayed by the author. When it was written the subject was a particularly thorny one to handle, and it undoubtedly required much courage to tackle the origin and development of the human race from a purely critical and scientific standpoint. It must be admitted on all hands that the result was eminently successful, taking into account the paucity of the available material, and the "Antiquity of Man" must ever remain one of the classics of prehistoric archaeology. This edition of the "Antiquity of Man" has been undertaken in order to place before the public in an easily accessible form one of the best known works of the great geologist Sir Charles Lyell; the book had an immense influence in its own day, and it still remains one of the best general accounts of an increasingly important branch of knowledge. In order to avoid a multiplicity of notes and thus to save space, the nomenclature has been to a certain extent modernised: a new general table of strata has been inserted in the first chapter, in place of the one originally there printed, which was cumbrous and included many minor subdivisions of unnecessary minuteness. The notes have been kept as short as possible, and they frequently contain little more than references to recent literature elucidating the points under discussion in the text. R.H. RASTALL. 1914. BIBLIOGRAPHY. The passage of the Beresina (in verse), 1815. Principles of Geology, being an attempt to explain the former changes of the earth's surface, by reference to causes now in operation, 1830-33 (third edition, 1834; fourth, 1835; fifth, 1837; sixth, 1840; seventh, 1847; ninth, entirely revised edition, 1853; tenth, entirely revised edition, 1867, 1868; eleventh, entirely revised edition, 1872; twelfth, edited by L. Lyell, 1875). Elements of Geology, 1838 (second edition, 1841). A Manual of Elementary Geology (third and entirely revised edition of the former work, 1851; fourth and entirely revised edition, 1852; fifth, enlarged edition, 1855; Supplement to the fifth edition, 1857; second edition of the Supplement, revised, 1857). Elements of Geology, sixth edition, greatly enlarged, 1865. Travels in North America, with geological observations on the United States, Canada, and Nova Scotia, 1845. A Second Visit to the United States of North America, 1849. The Students' Elements of Geology, 1871 (second edition, revised and corrected, 1874; third, revised, with a table of British fossils [by R. Etheridge], 1878; fourth, revised by P.M. Duncan, with a table of British fossils [by R. Etheridge], 1884). The Geological Evidences of the Antiquity of Man, with remarks on theories of the origin of species by variation, 1863; (second edition, revised, 1863; third edition, revised, 1863; fourth edition, revised, 1873). There has also been published The Student's Lyell: a Manual of Elementary Geology, edited by J.W. Judd, 1896 (second edition revised and enlarged, 1911). LECTURES, ADDRESSES, AND ARTICLES: On a Recent Formation of Freshwater Limestone in Forfarshire ("Transactions of the Geological Society" 2nd series, volume 2, 1826, part 1). On a Dike of Serpentine in the County of Forfar ("Edinburgh Journal of Science" 1825). English Scientific Societies ("Quarterly Review" volume 34; three papers with Sir Roderick and Mrs. Murchison; "Edinburgh Philosophical Journal," 1829; abstract in "Proceedings of the Geological Society" 1; "Annales des Sciences Naturelles" 1829; abstract in "Proceedings of the Geological Society" 1). Address delivered at the Geological Society of London, 1836. Lectures on Geology--Eight Lectures on Geology, delivered at the Broadway Tabernacle, New York ("New York Tribune" 1842). A Paper on Madeira ("Quarterly Journal of the Geological Society" 10, 1853). On the Structure of Lavas which have Consolidated on Steep Slopes ("Philosophical Transactions" 1858). Address (to the British Association) 1864. TRANSLATIONS: Antiquity of Man, translated into French by M. Chaper, 1864; and into German by L. Buchner, 1874. Elements of Geology (sixth edition), translated into French by M. J. Gineston, 1867. Report, extracted from the "Aberdeen Free Press" and translated into French, of Sir C. Lyell's address before the British Association, 1859, under the title of Antiquities antediluviennes: L'homme fossile. LIFE: Life, Letters and Journals of Sir Charles Lyell, edited by his sister-in-law, Mrs. Lyell, 1881. See also: Life and Letters of Charles Darwin, 1887. Life and Letters of Sedgwick, by Clark and Hughes, 1890. LIST OF CONTENTS. CHAP. 1. INTRODUCTORY. Preliminary Remarks on the Subjects treated of in this Work. Definition of the terms Recent and Pleistocene. Tabular View of the entire Series of Fossiliferous Strata. CHAP. 2. RECENT PERIOD--DANISH PEAT AND SHELL MOUNDS-- SWISS LAKE-DWELLINGS. Works of Art in Danish Peat-Mosses. Remains of three Periods of Vegetation in the Peat. Ages of Stone, Bronze, and Iron. Shell-Mounds or ancient Refuse-Heaps of the Danish Islands. Change in geographical Distribution of Marine Mollusca since their Origin. Embedded Remains of Mammalia of Recent Species. Human Skulls of the same Period. Swiss Lake-Dwellings built on Piles. Stone and Bronze Implements found in them. Fossil Cereals and other Plants. Remains of Mammalia, wild and domesticated. No extinct Species. Chronological Computations of the Date of the Bronze and Stone Periods in Switzerland. Lake-Dwellings, or artificial Islands called "Crannoges," in Ireland. CHAP. 3. FOSSIL HUMAN REMAINS AND WORKS OF ART OF THE RECENT PERIOD--continued. Delta and Alluvial Plain of the Nile. Burnt Bricks in Egypt before the Roman Era. Borings in 1851-54. Ancient Mounds of the Valley of the Ohio. Their Antiquity. Sepulchral Mound at Santos in Brazil. Delta of the Mississippi. Ancient Human Remains in Coral Reefs of Florida. Changes in Physical Geography in the Human Period. Buried Canoes in Marine Strata near Glasgow. Upheaval since the Roman Occupation of the Shores of the Firth of Forth. Fossil Whales near Stirling. Upraised Marine Strata of Sweden on Shores of the Baltic and the Ocean. Attempts to compute their Age. CHAP. 4. PLEISTOCENE PERIOD--BONES OF MAN AND EXTINCT MAMMALIA IN BELGIAN CAVERNS. Earliest Discoveries in Caves of Languedoc of Human Remains with Bones of extinct Mammalia. Researches in 1833 of Dr. Schmerling in the Liege Caverns. Scattered Portions of Human Skeletons associated with Bones of Elephant and Rhinoceros. Distribution and probable Mode of Introduction of the Bones. Implements of Flint and Bone. Schmerling's Conclusions as to the Antiquity of Man ignored. Present State of the Belgian Caves. Human Bones recently found in Cave of Engihoul. Engulfed Rivers. Stalagmitic Crust. Antiquity of the Human Remains in Belgium how proved. CHAP. 5. PLEISTOCENE PERIOD--FOSSIL HUMAN SKULLS OF THE NEANDERTHAL AND ENGIS CAVES. Human Skeleton found in Cave near Dusseldorf. Its geological Position and probable Age. Its abnormal and ape-like Characters. Fossil Human Skull of the Engis Cave near Liege. Professor Huxley's Description of these Skulls. Comparison of each, with extreme Varieties of the native Australian Race. Range of Capacity in the Human and Simian Brains. Skull from Borreby in Denmark. Conclusions of Professor Huxley. Bearing of the peculiar Characters of the Neanderthal Skull on the Hypothesis of Transmutation. CHAP. 6. PLEISTOCENE ALLUVIUM AND CAVE DEPOSITS WITH FLINT IMPLEMENTS. General Position of Drift with extinct Mammalia in Valleys. Discoveries of M. Boucher de Perthes at Abbeville. Flint Implements found also at St. Acheul, near Amiens. Curiosity awakened by the systematic Exploration of the Brixham Cave. Flint Knives in same, with Bones of extinct Mammalia. Superposition of Deposits in the Cave. Visits of English and French Geologists to Abbeville and Amiens. CHAP. 7. PEAT AND PLEISTOCENE ALLUVIUM OF THE VALLEY OF THE SOMME. Geological Structure of the Valley of the Somme and of the surrounding Country. Position of Alluvium of different Ages. Peat near Abbeville. Its animal and vegetable Contents. Works of Art in Peat. Probable Antiquity of the Peat, and Changes of Level since its Growth began. Flint Implements of antique Type in older Alluvium. Their various Forms and great Numbers. CHAP. 8. PLEISTOCENE ALLUVIUM WITH FLINT IMPLEMENTS OF THE VALLEY OF THE SOMME--concluded. Fluvio-marine Strata, with Flint Implements, near Abbeville. Marine Shells in same. Cyrena fluminalis. Mammalia. Entire Skeleton of Rhinoceros. Flint Implements, why found low down in Fluviatile Deposits. Rivers shifting their Channels. Relative Ages of higher and lower-level Gravels. Section of Alluvium of St. Acheul. Two Species of Elephant and Hippopotamus coexisting with Man in France. Volume of Drift, proving Antiquity of Flint Implements. Absence of Human Bones in tool-bearing Alluvium, how explained. Value of certain Kinds of negative Evidence tested thereby. Human Bones not found in drained Lake of Haarlem. CHAP. 9. WORKS OF ART IN PLEISTOCENE ALLUVIUM OF FRANCE AND ENGLAND. Flint Implements in ancient Alluvium of the Basin of the Seine. Bones of Man and of extinct Mammalia in the Cave of Arcy. Extinct Mammalia in the Valley of the Oise. Flint Implement in Gravel of same Valley. Works of Art in Pleistocene Drift in Valley of the Thames. Musk Ox. Meeting of northern and southern Fauna. Migrations of Quadrupeds. Mammals of Mongolia. Chronological Relation of the older Alluvium of the Thames to the Glacial Drift. Flint Implements of Pleistocene Period in Surrey, Middlesex, Kent, Bedfordshire, and Suffolk. CHAP. 10. CAVERN DEPOSITS, AND PLACES OF SEPULTURE OF THE PLEISTOCENE PERIOD. Flint Implements in Cave containing Hyaena and other extinct Mammalia in Somersetshire. Caves of the Gower Peninsula in South Wales. Rhinoceros hemitoechus. Ossiferous Caves near Palermo. Sicily once part of Africa. Rise of Bed of the Mediterranean to the Height of three hundred Feet in the Human Period in Sardinia. Burial-place of Pleistocene Date of Aurignac in the South of France. Rhinoceros tichorhinus eaten by Man. M. Lartet on extinct Mammalia and Works of Art found in the Aurignac Cave. Relative Antiquity of the same considered. CHAP. 11. AGE OF HUMAN FOSSILS OF LE PUY IN CENTRAL FRANCE AND OF NATCHEZ ON THE MISSISSIPPI DISCUSSED. Question as to the Authenticity of the Fossil Man of Denise, near Le Puy-en-Velay, considered. Antiquity of the Human Race implied by that Fossil. Successive Periods of Volcanic Action in Central France. With what Changes in the Mammalian Fauna they correspond. The Elephas meridionalis anterior in Time to the Implement-bearing Gravel of St. Acheul. Authenticity of the Human Fossil of Natchez on the Mississippi discussed. The Natchez Deposit, containing Bones of Mastodon and Megalonyx, probably not older than the Flint Implements of St. Acheul. CHAP. 12. ANTIQUITY OF MAN RELATIVELY TO THE GLACIAL PERIOD AND TO THE EXISTING FAUNA AND FLORA. Chronological Relation of the Glacial Period, and the earliest known Signs of Man's Appearance in Europe. Series of Tertiary Deposits in Norfolk and Suffolk immediately antecedent to the Glacial Period. Gradual Refrigeration of Climate proved by the Marine Shells of successive Groups. Marine Newer Pliocene Shells of Northern Character near Woodbridge. Section of the Norfolk Cliffs. Norwich Crag. Forest Bed and Fluvio-marine Strata. Fossil Plants and Mammalia of the same. Overlying Boulder Clay and Contorted Drift. Newer freshwater Formation of Mundesley compared to that of Hoxne. Great Oscillations of Level implied by the Series of Strata in the Norfolk Cliffs. Earliest known Date of Man long subsequent to the existing Fauna and Flora. CHAP. 13. CHRONOLOGICAL RELATIONS OF THE GLACIAL PERIOD AND THE EARLIEST SIGNS OF MAN'S APPEARANCE IN EUROPE. Chronological Relations of the Close of the Glacial Period and the earliest geological Signs of the Appearance of Man. Effects of Glaciers and Icebergs in polishing and scoring Rocks. Scandinavia once encrusted with Ice like Greenland. Outward Movement of Continental Ice in Greenland. Mild Climate of Greenland in the Miocene Period. Erratics of Recent Period in Sweden. Glacial State of Sweden in the Pleistocene Period. Scotland formerly encrusted with Ice. Its subsequent Submergence and Re-elevation. Latest Changes produced by Glaciers in Scotland. Remains of the Mammoth and Reindeer in Scotch Boulder Clay. Parallel Roads of Glen Roy formed in Glacier Lakes. Comparatively modern Date of these Shelves. CHAP. 14. CHRONOLOGICAL RELATIONS OF THE GLACIAL PERIOD AND THE EARLIEST SIGNS OF MAN'S APPEARANCE IN EUROPE--continued. Signs of extinct Glaciers in Wales. Great Submergence of Wales during the Glacial Period proved by Marine Shells. Still greater Depression inferred from Stratified Drift. Scarcity of Organic Remains in Glacial Formations. Signs of extinct Glaciers in England. Ice Action in Ireland. Maps illustrating successive Revolutions in Physical Geography during the Pleistocene Period. Southernmost Extent of Erratics in England. Successive Periods of Junction and Separation of England, Ireland, and the Continent. Time required for these Changes. Probable Causes of the Upheaval and Subsidence of the Earth's Crust. Antiquity of Man considered in relation to the Age of the existing Fauna and Flora. CHAP. 15. EXTINCT GLACIERS OF THE ALPS AND THEIR CHRONOLOGICAL RELATION TO THE HUMAN PERIOD. Extinct Glaciers of Switzerland. Alpine Erratic Blocks on the Jura. Not transported by floating Ice. Extinct Glaciers of the Italian Side of the Alps. Theory of the Origin of Lake-Basins by the erosive Action of Glaciers considered. Successive phases in the Development of Glacial Action in the Alps. Probable Relation of these to the earliest known Date of Man. Correspondence of the same with successive Changes in the Glacial Condition of the Scandinavian and British Mountains. Cold Period in Sicily and Syria. CHAP. 16. HUMAN REMAINS IN THE LOESS, AND THEIR PROBABLE AGE. Nature, Origin, and Age of the Loess of the Rhine and Danube. Impalpable Mud produced by the Grinding Action of Glaciers. Dispersion of this Mud at the Period of the Retreat of the great Alpine Glaciers. Continuity of the Loess from Switzerland to the Low Countries. Characteristic Organic Remains not Lacustrine. Alpine Gravel in the Valley of the Rhine covered by Loess. Geographical Distribution of the Loess and its Height above the Sea. Fossil Mammalia. Loess of the Danube. Oscillations in the Level of the Alps and lower Country required to explain the Formation and Denudation of the Loess. More rapid Movement of the Inland Country. The same Depression and Upheaval might account for the Advance and Retreat of the Alpine Glaciers. Himalayan Mud of the Plains of the Ganges compared to European Loess. Human Remains in Loess near Maestricht, and their probable Antiquity. CHAP. 17. POST-GLACIAL DISLOCATIONS AND FOLDINGS OF CRETACEOUS AND DRIFT STRATA IN THE ISLAND OF MOEN, IN DENMARK. Geological Structure of the Island of Moen. Great Disturbances of the Chalk posterior in Date to the Glacial Drift, with Recent Shells. M. Puggaard's Sections of the Cliffs of Moen. Flexures and Faults common to the Chalk and Glacial Drift. Different Direction of the Lines of successive Movement, Fracture, and Flexure. Undisturbed Condition of the Rocks in the adjoining Danish Islands. Unequal Movements of Upheaval in Finmark. Earthquake of New Zealand in 1855. Predominance in all Ages of uniform Continental Movements over those by which the Rocks are locally convulsed. CHAP. 18. THE GLACIAL PERIOD IN NORTH AMERICA. Post-glacial Strata containing Remains of Mastodon giganteus in North America. Scarcity of Marine Shells in Glacial Drift of Canada and the United States. Greater southern Extension of Ice-action in North America than in Europe. Trains of Erratic Blocks of vast Size in Berkshire, Massachusetts. Description of their Linear Arrangement and Points of Departure. Their Transportation referred to Floating and Coast Ice. General Remarks on the Causes of former Changes of Climate at successive geological Epochs. Supposed Effects of the Diversion of the Gulf Stream in a Northerly instead of North-Easterly Direction. Development of extreme Cold on the opposite Sides of the Atlantic in the Glacial period not strictly simultaneous. Effect of Marine Currents on Climate. Pleistocene Submergence of the Sahara. CHAP. 19. RECAPITULATION OF GEOLOGICAL PROOFS OF MAN'S ANTIQUITY. Recapitulation of Results arrived at in the earlier Chapters. Ages of Stone and Bronze. Danish Peat and Kitchen-Middens. Swiss Lake-Dwellings. Local Changes in Vegetation and in the wild and domesticated Animals and in Physical Geography coeval with the Age of Bronze and the later Stone Period. Estimates of the positive Date of some Deposits of the later Stone Period. Ancient Division of the Age of Stone of St. Acheul and Aurignac. Migrations of Man in that Period from the Continent to England in Post-Glacial Times. Slow Rate of Progress in barbarous Ages. Doctrine of the superior Intelligence and Endowments of the original Stock of Mankind considered. Opinions of the Greeks and Romans, and their Coincidence with those of the Modern Progressionist. CHAP. 20. THEORIES OF PROGRESSION AND TRANSMUTATION. Antiquity and Persistence in Character of the existing Races of Mankind. Theory of their Unity of Origin considered. Bearing of the Diversity of Races on the Doctrine of Transmutation. Difficulty of defining the Terms "Species" and "Race." Lamarck's Introduction of the Element of Time into the Definition of a Species. His Theory of Variation and Progression. Objections to his Theory, how far answered. Arguments of modern Writers in favour of Progression in the Animal and Vegetable World. The old Landmarks supposed to indicate the first Appearance of Man, and of different Classes of Animals, found to be erroneous. Yet the Theory of an advancing Series of Organic Beings not inconsistent with Facts. Earliest known Fossil Mammalia of low Grade. No Vertebrata as yet discovered in the oldest Fossiliferous Rocks. Objections to the Theory of Progression considered. Causes of the Popularity of the Doctrine of Progression as compared to that of Transmutation. CHAP. 21. ON THE ORIGIN OF SPECIES BY VARIATION AND NATURAL SELECTION. Mr. Darwin's Theory of the Origin of Species by Natural Selection. Memoir by Mr. Wallace. Manner in which favoured Races prevail in the Struggle for Existence. Formation of new Races by breeding. Hypotheses of definite and indefinite Modifiability equally arbitrary. Competition and Extinction of Races. Progression not a necessary Accompaniment of Variation. Distinct Classes of Phenomena which Natural Selection explains. Unity of Type, Rudimentary Organs, Geographical Distribution, Relation of the extinct to the living Fauna and Flora, and mutual Relations of successive Groups of Fossil Forms. Light thrown on Embryological Development by Natural Selection. Why large Genera have more variable Species than small ones. Dr. Hooker on the Evidence afforded by the Vegetable Kingdom in favour of Creation by Variation. Steenstrup on alternation of Generations. How far the Doctrine of Independent Creation is opposed to the Laws now governing the Migration of Species. CHAP. 22. OBJECTIONS TO THE HYPOTHESIS OF TRANSMUTATION CONSIDERED. Statement of Objections to the Hypothesis of Transmutation founded on the Absence of Intermediate Forms. Genera of which the Species are closely allied. Occasional Discovery of the missing Links in a Fossil State. Davidson's Monograph on the Brachiopoda. Why the Gradational Forms, when found, are not accepted as Evidence of Transmutation. Gaps caused by Extinction of Races and Species. Vast Tertiary Periods during which this Extinction has been going on in the Fauna and Flora now existing. Genealogical Bond between Miocene and Recent Plants and Insects. Fossils of Oeningen. Species of Insects in Britain and North America represented by distinct Varieties. Falconer's Monograph on living and fossil Elephants. Fossil Species and Genera of the Horse Tribe in North and South America. Relation of the Pliocene Mammalia of North America, Asia, and Europe. Species of Mammalia, though less persistent than the Mollusca, change slowly. Arguments for and against Transmutation derived from the Absence of Mammalia in Islands. Imperfection of the Geological Record. Intercalation of newly discovered Formation of intermediate Age in the chronological Series. Reference of the St. Cassian Beds to the Triassic Periods. Discovery of new organic Types. Feathered Archaeopteryx of the Oolite. CHAP. 23. ORIGIN AND DEVELOPMENT OF LANGUAGES AND SPECIES COMPARED. Aryan Hypothesis and Controversy. The Races of Mankind change more slowly than their Languages. Theory of the gradual Origin of Languages. Difficulty of defining what is meant by a Language as distinct from a Dialect. Great Number of extinct and living Tongues. No European Language a Thousand Years old. Gaps between Languages, how caused. Imperfection of the Record. Changes always in Progress. Struggle for Existence between rival Terms and Dialects. Causes of Selection. Each Language formed slowly in a single Geographical Area. May die out gradually or suddenly. Once lost can never be revived. Mode of Origin of Languages and Species a Mystery. Speculations as to the Number of original Languages or Species unprofitable. CHAP. 24. BEARING OF THE DOCTRINE OF TRANSMUTATION ON THE ORIGIN OF MAN, AND HIS PLACE IN THE CREATION. Whether Man can be regarded as an Exception to the Rule if the Doctrine of Transmutation be embraced for the rest of the Animal Kingdom. Zoological Relations of Man to other Mammalia. Systems of Classification. Term Quadrumanous, why deceptive. Whether the Structure of the Human Brain entitles Man to form a distinct Sub-class of the Mammalia. Intelligence of the lower Animals compared to the Intellect and Reason of Man. Grounds on which Man has been referred to a distinct Kingdom of Nature. Immaterial Principle common to Man and Animals. Non-discovery of intermediate Links among Fossil Anthropomorphous Species. Hallam on the compound Nature of Man, and his Place in the Creation. Great Inequality of mental Endowment in different Human Races and Individuals developed by Variation and ordinary Generation. How far a corresponding Divergence in physical Structure may result from the Working of the same Causes. Concluding remarks. NOTES. PLATES AND FIGURES. PLATE 1. A VILLAGE BUILT ON PILES IN A SWISS LAKE. FIGURE 1. SECTION OF THE NEANDERTHAL CAVE. FIGURE 2. SIDE VIEW OF THE CAST OF PART OF A HUMAN SKULL FOUND BY DR. SCHMERLING EMBEDDED AMONGST THE REMAINS OF EXTINCT MAMMALIA IN THE CAVE OF ENGIS. FIGURE 3. SIDE VIEW OF THE CAST OF A PART OF A HUMAN SKULL FROM A CAVE IN THE NEANDERTHAL. FIGURE 4. OUTLINE OF THE SKULL OF AN ADULT CHIMPANZEE, OF THAT FROM THE NEANDERTHAL, AND OF THAT OF A EUROPEAN. FIGURE 5. SKULL ASSOCIATED WITH GROUND FLINT IMPLEMENTS. FIGURE 6. OUTLINES OF THE SKULL FROM THE NEANDERTHAL, OF AN AUSTRALIAN SKULL FROM PORT ADELAIDE, AND OF THE SKULL FROM THE CAVE OF ENGIS. FIGURE 7. SECTION ACROSS THE VALLEY OF THE SOMME IN PICARDY. FIGURE 8. FLINT IMPLEMENT FROM ST. ACHEUL, NEAR AMIENS, OF THE SPEAR-HEAD SHAPE. FIGURE 9. OVAL-SHAPED FLINT HATCHET FROM MAUTORT. FIGURE 10. FLINT TOOL FROM ST. ACHEUL. FIGURES 11, 12 AND 13. DENDRITES ON SURFACES OF FLINT HATCHETS IN THE DRIFT OF ST. ACHEUL. FIGURE 14. FLINT KNIFE OR FLAKE FROM BELOW THE SAND CONTAINING Cyrena fluminalis. FIGURE 15. FOSSILS OF THE WHITE CHALK. FIGURE 16. SECTION OF FLUVIO-MARINE STRATA, CONTAINING FLINT IMPLEMENTS AND BONES OF EXTINCT MAMMALIA. FIGURE 17. Cyrena fluminalis, O.F. Muller, sp. FIGURE 18. Elephas primigenius. FIGURE 19. Elephas antiquus, Falconer. FIGURE 20. Elephas meridionalis, Nesti. FIGURE 21. SECTION OF GRAVEL PIT CONTAINING FLINT IMPLEMENTS AT ST. ACHEUL. FIGURE 22. CONTORTED FLUVIATILE STRATA AT ST. ACHEUL. FIGURE 23. SECTION ACROSS THE VALLEY OF THE OUSE. FIGURE 24. SECTION SHOWING THE POSITION OF THE FLINT WEAPONS AT HOXNE. FIGURE 25. SECTION OF PART OF THE HILL OF FAJOLES. FIGURE 26. SECTION THROUGH THE ALLUVIAL PLAIN OF THE MISSISSIPPI. FIGURE 27. DIAGRAM TO ILLUSTRATE THE GENERAL SUCCESSION OF THE STRATA IN THE NORFOLK CLIFFS. FIGURE 28. Cyclas (Pisidium) amnica var.(?) FIGURE 29. CLIFF 50 FEET HIGH BETWEEN BACTON GAP AND MUNDESLEY. FIGURE 30. FOLDING OF THE STRATA BETWEEN EAST AND WEST RUNTON. FIGURE 31. SECTION OF CONCENTRIC BEDS WEST OF CROMER. FIGURE 32. INCLUDED PINNACLE OF CHALK AT OLD HYTHE POINT. FIGURE 33. SECTION OF THE NEWER FRESH-WATER FORMATION IN THE CLIFFS AT MUNDESLEY. FIGURE 34. Paludina marginata, Michaud (P. minuta, Strickland). Hydrobia marginata. FIGURE 35. OVAL AND FLATTISH PEBBLES. PLATE 2. VIEW OF THE MOUTHS OF GLEN ROY AND GLEN SPEAN. FIGURE 36. MAP OF THE PARALLEL ROADS OF GLEN ROY. FIGURE 37. SECTION THROUGH SIDE OF LOCH. FIGURE 38. DOME-SHAPED ROCKS, OR "ROCHES MOUTONEES." FIGURE 39. MAP OF THE BRITISH ISLES AND PART OF THE NORTH-WEST OF EUROPE, SHOWING THE GREAT AMOUNT OF SUPPOSED SUBMERGENCE OF LAND BENEATH THE SEA DURING PART OF THE GLACIAL PERIOD. FIGURE 40. MAP SHOWING WHAT PARTS OF THE BRITISH ISLANDS WOULD REMAIN ABOVE WATER AFTER A SUBSIDENCE OF THE AREA TO THE EXTENT OF 600 FEET. FIGURE 41. MAP OF PART OF THE NORTH-WEST OF EUROPE, INCLUDING THE BRITISH ISLES, SHOWING THE EXTENT OF SEA WHICH WOULD BECOME LAND IF THERE WERE A GENERAL RISE OF THE AREA TO THE EXTENT OF 600 FEET. FIGURE 42. MAP SHOWING THE SUPPOSED COURSE OF THE ANCIENT AND NOW EXTINCT GLACIER OF THE RHONE. FIGURE 43. MAP OF THE MORAINES OF EXTINCT GLACIERS EXTENDING FROM THE ALPS INTO THE PLAINS OF THE PO NEAR TURIN. FIGURE 44. Succinea oblonga. FIGURE 45. Pupa muscorum. FIGURE 46. Helix hispida, Lin.; H. plebeia, Drap. FIGURE 47. SOUTHERN EXTREMITY OF MOENS KLINT. FIGURE 48. SECTION OF MOENS KLINT. FIGURE 49. POST-GLACIAL DISTURBANCES OF VERTICAL, FOLDED, AND SHIFTED STRATA OF CHALK AND DRIFT, IN THE DRONNINGESTOL. FIGURE 50. MAP SHOWING THE RELATIVE POSITION AND DIRECTION OF SEVEN TRAINS OF ERRATIC BLOCKS IN BERKSHIRE, MASSACHUSETTS, AND IN PART OF THE STATE OF NEW YORK. FIGURE 51. ERRATIC DOME-SHAPED BLOCK OF COMPACT CHLORITIC ROCK. FIGURE 52. SECTION SHOWING THE POSITION OF THE BLOCK IN FIGURE 51. FIGURE 53. SECTION THROUGH CANAAN AND RICHMOND VALLEYS AT A TIME WHEN THEY WERE MARINE CHANNELS. FIGURE 54. UPPER SURFACE OF BRAIN OF CHIMPANZEE, DISTORTED. FIGURE 55. SIDE VIEW OF BRAIN OF CHIMPANZEE, DISTORTED. FIGURE 56. CORRECT SIDE VIEW OF CHIMPANZEE'S BRAIN. FIGURE 57. CORRECT VIEW OF UPPER SURFACE OF CHIMPANZEE'S BRAIN. FIGURE 58. SIDE VIEW OF HUMAN BRAIN.) GEOLOGICAL EVIDENCE OF THE ANTIQUITY OF MAN. CHAPTER 1. -- INTRODUCTORY. Preliminary Remarks on the Subjects treated of in this Work. Definition of the Terms Recent and Pleistocene. Tabular View of the entire Series of Fossiliferous Strata. No subject has lately excited more curiosity and general interest among geologists and the public than the question of the Antiquity of the Human Race--whether or no we have sufficient evidence in caves, or in the superficial deposits commonly called drift or "diluvium," to prove the former co-existence of man with certain extinct mammalia. For the last half-century the occasional occurrence in various parts of Europe of the bones of Man or the works of his hands in cave-breccias and stalagmites, associated with the remains of the extinct hyaena, bear, elephant, or rhinoceros, has given rise to a suspicion that the date of Man must be carried farther back than we had heretofore imagined. On the other hand extreme reluctance was naturally felt on the part of scientific reasoners to admit the validity of such evidence, seeing that so many caves have been inhabited by a succession of tenants and have been selected by Man as a place not only of domicile, but of sepulture, while some caves have also served as the channels through which the waters of occasional land-floods or engulfed rivers have flowed, so that the remains of living beings which have peopled the district at more than one era may have subsequently been mingled in such caverns and confounded together in one and the same deposit. But the facts brought to light in 1858, during the systematic investigation of the Brixham cave, near Torquay in Devonshire, which will be described in the sequel, excited anew the curiosity of the British public and prepared the way for a general admission that scepticism in regard to the bearing of cave evidence in favour of the antiquity of Man had previously been pushed to an extreme. Since that period many of the facts formerly adduced in favour of the co-existence in ancient times of Man with certain species of mammalia long since extinct have been re-examined in England and on the Continent, and new cases bearing on the same question, whether relating to caves or to alluvial strata in valleys, have been brought to light. To qualify myself for the appreciation and discussion of these cases, I have visited in the course of the last three years many parts of England, France, and Belgium, and have communicated personally or by letter with not a few of the geologists, English and foreign, who have taken part in these researches. Besides explaining in the present volume the results of this inquiry, I shall give a description of the glacial formations of Europe and North America, that I may allude to the theories entertained respecting their origin, and consider their probable relations in a chronological point of view to the human epoch, and why throughout a great part of the northern hemisphere they so often interpose an abrupt barrier to all attempts to trace farther back into the past the signs of the existence of Man upon the earth. In the concluding chapters I shall offer a few remarks on the recent modifications of the Lamarckian theory of progressive development and transmutation, which are suggested by Mr. Darwin's work on the "Origin of Species by Variation and Natural Selection," and the bearing of this hypothesis on the different races of mankind and their connection with other parts of the animal kingdom. NOMENCLATURE. Some preliminary explanation of the nomenclature adopted in the following pages will be indispensable, that the meaning attached to the terms Recent, Pleistocene, and Post-Tertiary may be correctly understood. [1] Previously to the year 1833, when I published the third volume of the "Principles of Geology," the strata called Tertiary had been divided by geologists into Lower, Middle, and Upper; the Lower comprising the oldest formations of the environs of Paris and London, with others of like age; the Middle, those of Bordeaux and Touraine; and the Upper, all that lay above or were newer than the last-mentioned group. When engaged in 1828 in preparing for the press the treatise on geology above alluded to, I conceived the idea of classing the whole of this series of strata according to the different degrees of affinity which their fossil testacea bore to the living fauna. Having obtained information on this subject during my travels on the Continent, I learnt that M. Deshayes of Paris, already celebrated as a conchologist, had been led independently by the study of a large collection of Recent and fossil shells to very similar views respecting the possibility of arranging the Tertiary formations in chronological order, according to the proportional number of species of shells identical with living ones, which characterised each of the successive groups above mentioned. After comparing 3000 fossil species with 5000 living ones, the result arrived at was, that in the lower Tertiary strata there were about 3 1/2 per cent identical with Recent; in the middle Tertiary (the faluns of the Loire and Gironde), about 17 per cent; and in the upper tertiary, from 35 to 50, and sometimes in the most modern beds as much as 90 to 95 per cent. For the sake of clearness and brevity, I proposed to give short technical names to these sets of strata, or the periods to which they respectively belonged. I called the first or oldest of them Eocene, the second Miocene, and the third Pliocene. The first of the above terms, Eocene, is derived from Greek eos, dawn, and Greek kainos, recent; because an extremely small proportion of the fossil shells of this period could be referred to living species, so that this era seemed to indicate the dawn of the present testaceous fauna, no living species of shells having been detected in the antecedent or Secondary rocks. Some conchologists are now unwilling to allow that any Eocene species of shell has really survived to our times so unaltered as to allow of its specific identification with a living species. I cannot enter in this place into this wide controversy. It is enough at present to remark that the character of the Eocene fauna, as contrasted with that of the antecedent Secondary formations, wears a very modern aspect, and that some able living conchologists still maintain that there are Eocene shells not specifically distinguishable from those now extant; though they may be fewer in number than was supposed in 1833. The term Miocene (from Greek meion, less; and Greek kainos, recent) is intended to express a minor proportion of Recent species (of testacea); the term Pliocene (from Greek pleion, more; and Greek kainos, recent), a comparative plurality of the same. It has sometimes been objected to this nomenclature that certain species of infusoria found in the chalk are still existing, and, on the other hand, the Miocene and Older Pliocene deposits often contain the remains of mammalia, reptiles, and fish, exclusively of extinct species. But the reader must bear in mind that the terms Eocene, Miocene, and Pliocene were originally invented with reference purely to conchological data, and in that sense have always been and are still used by me. Since the first introduction of the terms above defined, the number of new living species of shells obtained from different parts of the globe has been exceedingly great, supplying fresh data for comparison, and enabling the palaeontologist to correct many erroneous identifications of fossil and Recent forms. New species also have been collected in abundance from Tertiary formations of every age, while newly discovered groups of strata have filled up gaps in the previously known series. Hence modifications and reforms have been called for in the classifications first proposed. The Eocene, Miocene, and Pliocene periods have been made to comprehend certain sets of strata of which the fossils do not always conform strictly in the proportion of Recent to extinct species with the definitions first given by me, or which are implied in the etymology of those terms. These innovations have been treated of in my "Elements or Manual of Elementary Geology," and in the Supplement to the fifth edition of the same, published in 1859, where some modifications of my classification, as first proposed, are introduced; but I need not dwell on these on the present occasion, as the only formations with which we shall be concerned in the present volume are those of the most modern date, or the Post-Tertiary. It will be convenient to divide these into two groups, the Recent and the Pleistocene. In the Recent we may comprehend those deposits in which not only all the shells but all the fossil mammalia are of living species; in the Pleistocene those strata in which, the shells being Recent, a portion, and often a considerable one, of the accompanying fossil quadrupeds belongs to extinct species. Cases will occur where it may be scarcely possible to draw the line of demarcation between the Newer Pliocene and Pleistocene, or between the latter and the recent deposits; and we must expect these difficulties to increase rather than diminish with every advance in our knowledge, and in proportion as gaps are filled up in the series of geological records. The annexed tabular view (Table 1/1) of the whole series of fossiliferous strata will enable the reader to see at a glance the chronological relation of the Recent and Pleistocene to the antecedent periods. [2] TABLE 1/1. STRATIFIED ROCKS. KAINOZOIC OR TERTIARY: Pleistocene and Recent. Pliocene. Miocene. Oligocene. Eocene. MESOZOIC OR SECONDARY: Cretaceous. Jurassic. Triassic. PALAEOZOIC OR PRIMARY: Permian. Carboniferous. Devonian or old Red Sandstone. Silurian. Ordovician. Cambrian. PRECAMBRIAN OR ARCHAEAN. CHAPTER 2. -- RECENT PERIOD--DANISH PEAT AND SHELL MOUNDS--SWISS LAKE-DWELLINGS. [Illustration: PLATE 1. A VILLAGE BUILT ON PILES IN A SWISS LAKE] (Restored by Dr. F. Keller, partly from Dumont D'Urville's Sketch of similar habitations in New Guinea.) Works of Art in Danish Peat-Mosses. Remains of three Periods of Vegetation in the Peat. Ages of Stone, Bronze, and Iron. Shell-Mounds or ancient Refuse-Heaps of the Danish Islands. Change in geographical Distribution of Marine Mollusca since their Origin. Embedded Remains of Mammalia of Recent Species. Human Skulls of the same Period. Swiss Lake-Dwellings built on Piles. Stone and Bronze Implements found in them. Fossil Cereals and other Plants. Remains of Mammalia, wild and domesticated. No extinct Species. Chronological Computations of the Date of the Bronze and Stone Periods in Switzerland. Lake-Dwellings, or artificial Islands called "Crannoges," in Ireland. WORKS OF ART IN DANISH PEAT. When treating in the "Principles of Geology" of the changes of the earth which have taken place in comparatively modern times, I have spoken of the embedding of organic bodies and human remains in peat, and explained under what conditions the growth of that vegetable substance is going on in northern and humid climates. Of late years, since I first alluded to the subject, more extensive investigations have been made into the history of the Danish peat-mosses. Of the results of these inquiries I shall give a brief abstract in the present chapter, that we may afterwards compare them with deposits of older date, which throw light on the antiquity of the human race. The deposits of peat in Denmark,* varying in depth from 10 to 30 feet, have been formed in hollows or depressions in the northern drift or boulder formation hereafter to be described. (* An excellent account of these researches of Danish naturalists and antiquaries has been drawn up by an able Swiss geologist, M.A. Morlot, and will be found in the "Bulletin de la Societe Vaudoise des Sci. Nat." tome 6 Lausanne 1860.) The lowest stratum, 2 to 3 feet thick, consists of swamp-peat composed chiefly of moss or sphagnum, above which lies another growth of peat, not made up exclusively of aquatic or swamp plants. Around the borders of the bogs, and at various depths in them, lie trunks of trees, especially of the Scotch fir (Pinus sylvestris), often 3 feet in diameter, which must have grown on the margin of the peat-mosses, and have frequently fallen into them. This tree is not now, nor has ever been in historical times, a native of the Danish Islands, and when introduced there has not thriven; yet it was evidently indigenous in the human period, for Steenstrup has taken out with his own hands a flint instrument from below a buried trunk of one of these pines. It appears clear that the same Scotch fir was afterwards supplanted by the sessile variety of the common oak, of which many prostrate trunks occur in the peat at higher levels than the pines; and still higher the pedunculated variety of the same oak (Quercus robur, L.) occurs with the alder, birch (Betula verrucosa, Ehrh.), and hazel. The oak has now in its turn been almost superseded in Denmark by the common beech. Other trees, such as the white birch (Betula alba), characterise the lower part of the bogs, and disappear from the higher; while others again, like the aspen (Populus tremula), occur at all levels, and still flourish in Denmark. All the land and freshwater shells, and all the mammalia as well as the plants, whose remains occur buried in the Danish peat, are of Recent species. [3] It has been stated, that a stone implement was found under a buried Scotch fir at a great depth in the peat. By collecting and studying a vast variety of such implements, and other articles of human workmanship preserved in peat and in sand-dunes on the coast, as also in certain shell-mounds of the aborigines presently to be described, the Danish and Swedish antiquaries and naturalists, MM. Nilsson, Steenstrup, Forchhammer, Thomsen, Worsaae, and others, have succeeded in establishing a chronological succession of periods, which they have called the ages of stone, of bronze, and of iron, named from the materials which have each in their turn served for the fabrication of implements. The age of stone in Denmark coincided with the period of the first vegetation, or that of the Scotch fir, and in part at least with the second vegetation, or that of the oak. But a considerable portion of the oak epoch coincided with "the age of bronze," for swords and shields of that metal, now in the Museum of Copenhagen, have been taken out of peat in which oaks abound. The age of iron corresponded more nearly with that of the beech tree.* (* Morlot "Bulletin de la Societe Vaudoise des Sci. Nat." tome 6 page 292.) [4] M. Morlot, to whom we are indebted for a masterly sketch of the recent progress of this new line of research, followed up with so much success in Scandinavia and Switzerland, observes that the introduction of the first tools made of bronze among a people previously ignorant of the use of metals, implies a great advance in the arts, for bronze is an alloy of about nine parts of copper and one of tin; and although the former metal, copper, is by no means rare, and is occasionally found pure or in a native state, tin is not only scarce but never occurs native. To detect the existence of this metal in its ore, then to disengage it from the matrix, and finally, after blending it in due proportion with copper, to cast the fused mixture in a mould, allowing time for it to acquire hardness by slow cooling, all this bespeaks no small sagacity and skilful manipulation. Accordingly, the pottery found associated with weapons of bronze is of a more ornamental and tasteful style than any which belongs to the age of stone. Some of the moulds in which the bronze instruments were cast, and "tags," as they are called, of bronze, which are formed in the hole through which the fused metal was poured, have been found. The number and variety of objects belonging to the age of bronze indicates its long duration, as does the progress in the arts implied by the rudeness of the earlier tools, often mere repetitions of those of the stone age, as contrasted with the more skilfully worked weapons of a later stage of the same period. It has been suggested that an age of copper must always have intervened between that of stone and bronze; but if so, the interval seems to have been short in Europe, owing apparently to the territory occupied by the aboriginal inhabitants having been invaded and conquered by a people coming from the East, to whom the use of swords, spears, and other weapons of bronze was familiar. Hatchets, however, of copper have been found in the Danish peat. The next stage of improvement, or that manifested by the substitution of iron for bronze, indicates another stride in the progress of the arts. Iron never presents itself, except in meteorites, in a native state, so that to recognise its ores, and then to separate the metal from its matrix, demands no inconsiderable exercise of the powers of observation and invention. To fuse the ore requires an intense heat, not to be obtained without artificial appliances, such as pipes inflated by the human breath, or bellows, or some other suitable machinery. DANISH SHELL-MOUNDS, OR KJOKKENMODDING.* (* Mr. John Lubbock published, after these sheets were written, an able paper on the Danish "Shell-mounds" in the October number of the "Natural History Review" 1861 page 489, in which he has described the results of a recent visit to Denmark, made by him in company with Mr. Busk.) In addition to the peat-mosses, another class of memorials found in Denmark has thrown light on the pre-historical age. At certain points along the shores of nearly all the Danish islands, mounds may be seen, consisting chiefly of thousands of cast-away shells of the oyster, cockle, and other molluscs of the same species as those which are now eaten by Man. These shells are plentifully mixed up with the bones of various quadrupeds, birds, and fish, which served as the food of the rude hunters and fishers by whom the mounds were accumulated. I have seen similar large heaps of oysters, and other marine shells with interspersed stone implements, near the seashore, both in Massachusetts and in Georgia, U.S.A., left by the native North American Indians at points near to which they were in the habit of pitching their wigwams for centuries before the white man arrived. Such accumulations are called by the Danes, Kjokkenmodding, or "kitchen-middens." Scattered all through them are flint knives, hatchets, and other instruments of stone, horn, wood, and bone, with fragments of coarse pottery, mixed with charcoal and cinders, but never any implements of bronze, still less of iron. The stone hatchets and knives had been sharpened by rubbing, and in this respect are one degree less rude than those of an older date, associated in France with the bones of extinct mammalia, of which more in the sequel. The mounds vary in height from 3 to 10 feet, and in area are some of them 1000 feet long, and from 150 to 200 wide. They are rarely placed more than 10 feet above the level of the sea, and are confined to its immediate neighbourhood, or if not (and there are cases where they are several miles from the shore), the distance is ascribable to the entrance of a small stream, which has deposited sediment, or to the growth of a peaty swamp, by which the land has been made to advance on the Baltic, as it is still doing in many places, aided, according to Puggaard, by a very slow upheaval of the whole country at the rate of 2 or 3 inches in a century. There is also another geographical fact equally in favour of the antiquity of the mounds, namely, that they are wanting on those parts of the coast which border the Western Ocean, or exactly where the waves are now slowly eating away the land. There is every reason to presume that originally there were stations along the coast of the North Sea as well as that of the Baltic, but by the gradual undermining of the cliffs they have all been swept away. Another striking proof, perhaps the most conclusive of all, that the "kitchen-middens" are very old, is derived from the character of their embedded shells. These consist entirely of living species; but, in the first place, the common eatable oyster is among them, attaining its full size, whereas the same Ostrea edulis cannot live at present in the brackish waters of the Baltic except near its entrance, where, whenever a north-westerly gale prevails, a current setting in from the ocean pours in a great body of salt water. Yet it seems that during the whole time of the accumulation of the "kitchen-middens" the oyster flourished in places from which it is now excluded. In like manner the eatable cockle, mussel, and periwinkle (Cardium edule, Mytilus edulis, and Littorina littorea), which are met with in great numbers in the "middens," are of the ordinary dimensions which they acquire in the ocean, whereas the same species now living in the adjoining parts of the Baltic only attain a third of their natural size, being stunted and dwarfed in their growth by the quantity of fresh water poured by rivers into that inland sea.* (* See "Principles of Geology" chapter 30.) Hence we may confidently infer that in the days of the aboriginal hunters and fishers, the ocean had freer access than now to the Baltic, communicating probably through the peninsula of Jutland, Jutland having been at no remote period an archipelago. Even in the course of the nineteenth century, the salt waters have made one irruption into the Baltic by the Lymfiord, although they have been now again excluded. It is also affirmed that other channels were open in historical times which are now silted up.* (* See Morlot "Bulletin de la Societe Vaudoise des Sci. Nat." tome 6.) If we next turn to the remains of vertebrata preserved in the mounds, we find that here also, as in the Danish peat-mosses, all the quadrupeds belong to species known to have inhabited Europe within the memory of Man. No remains of the mammoth, or rhinoceros, or of any extinct species appear, except those of the wild bull (Bos urus, Linn., or Bos primigenius, Bojanus), which are in such numbers as to prove that the species was a favourite food of the ancient people. But as this animal was seen by Julius Caesar, and survived long after his time, its presence alone would not go far to prove the mounds to be of high antiquity. The Lithuanian aurochs or bison (Bos bison, L., Bos priscus, Boj.), which has escaped extirpation only because protected by the Russian Czars, surviving in one forest in Lithuania) has not yet been met with, but will no doubt be detected hereafter, as it has been already found in the Danish peat. The beaver, long since destroyed in Denmark, occurs frequently, as does the seal (Phoca Gryppus, Fab.), now very rare on the Danish coast. With these are mingled bones of the red deer and roe, but the reindeer has not yet been found. There are also the bones of many carnivora, such as the lynx, fox, and wolf, but no signs of any domesticated animals except the dog. The long bones of the larger mammalia have been all broken as if by some instrument, in such a manner as to allow of the extraction of the marrow, and the gristly parts have been gnawed off, as if by dogs, to whose agency is also attributed the almost entire absence of the bones of young birds and of the smaller bones and softer parts of the skeletons of birds in general, even of those of large size. In reference to the latter, it has been proved experimentally by Professor Steenstrup, that if the same species of birds are now given to dogs, they will devour those parts of the skeleton which are missing, and leave just those which are preserved in the old "kitchen-middens." The dogs of the mounds, the only domesticated animals, are of a smaller race than those of the bronze period, as shown by the peat-mosses, and the dogs of the bronze age are inferior in size and strength to those of the iron age. The domestic ox, horse, and sheep, which are wanting in the mounds, are confined to that part of the Danish peat which was formed in the ages of bronze and iron. Among the bones of birds, scarcely any are more frequent in the mounds than those of the auk (Alca impennis), now extinct. The Capercailzie (Tetrao urogallus) is also met with, and may, it is suggested, have fed on the buds of the Scotch fir in times when that tree flourished around the peat-bogs. The different stages of growth of the roedeer's horns, and the presence of the wild swan, now only a winter visitor, have been appealed to as proving that the aborigines resided in the same settlements all the year round. That they also ventured out to sea in canoes such as are now found in the peat-mosses, hollowed out of the trunk of a single tree, to catch fish far from land, is testified by the bony relics of several deep-sea species, such as the herring, cod, and flounder. The ancient people were not cannibals, for no human bones are mingled with the spoils of the chase. Skulls, however, have been obtained not only from peat, but from tumuli of the stone period believed to be contemporaneous with the mounds. These skulls are small and round, and have a prominent ridge over the orbits of the eyes, showing that the ancient race was of small stature, with round heads and overhanging eyebrows--in short, they bore a considerable resemblance to the modern Laplanders. The human skulls of the bronze age found in the Danish peat, and those of the iron period, are of an elongated form and larger size. There appear to be very few well-authenticated examples of crania referable to the bronze period--a circumstance no doubt attributable to the custom prevalent among the people of that era of burning their dead and collecting their bones in funeral urns. No traces of grain of any sort have hitherto been discovered, nor any other indication that the ancient people had any knowledge of agriculture. The only vegetable remains in the mounds are burnt pieces of wood and some charred substance referred by Dr. Forchhammer to the Zostera marina, a sea plant which was perhaps used in the production of salt. What may be the antiquity of the earliest human remains preserved in the Danish peat cannot be estimated in centuries with any approach to accuracy. In the first place, in going back to the bronze age, we already find ourselves beyond the reach of history or even of tradition. In the time of the Romans the Danish Isles were covered, as now, with magnificent beech forests. Nowhere in the world does this tree flourish more luxuriantly than in Denmark, and eighteen centuries seem to have done little or nothing towards modifying the character of the forest vegetation. Yet in the antecedent bronze period there were no beech trees, or at most but a few stragglers, the country being then covered with oak. In the age of stone again, the Scotch fir prevailed, and already there were human inhabitants in those old pine forests. How many generations of each species of tree flourished in succession before the pine was supplanted by the oak, and the oak by the beech, can be but vaguely conjectured, but the minimum of time required for the formation of so much peat must, according to the estimate of Steenstrup and other good authorities, have amounted to at least 4000 years; and there is nothing in the observed rate of the growth of peat opposed to the conclusion that the number of centuries may not have been four times as great, even though the signs of Man's existence have not yet been traced down to the lowest or amorphous stratum. As to the "kitchen-middens," they correspond in date to the older portion of the peaty record, or to the earliest part of the age of stone as known in Denmark. ANCIENT SWISS LAKE-DWELLINGS, BUILT ON PILES. [Illustration: Plate 1. Swiss Lake-Dwellings] In the shallow parts of many Swiss lakes, where there is a depth of no more than from 5 to 15 feet of water, ancient wooden piles are observed at the bottom sometimes worn down to the surface of the mud, sometimes projecting slightly above it. These have evidently once supported villages, nearly all of them of unknown date, but the most ancient of which certainly belonged to the age of stone, for hundreds of implements resembling those of the Danish shell-mounds and peat-mosses have been dredged up from the mud into which the piles were driven. The earliest historical account of such habitations is that given by Herodotus of a Thracian tribe, who dwelt, in the year 520 B.C., in Prasias, a small mountain-lake of Paeonia, now part of modern Roumelia.* (* Herodotus lib. 5 cap. 16. Rediscovered by M. de Ville "Natural History Review" volume 2 1862 page 486.) Their habitations were constructed on platforms raised above the lake, and resting on piles. They were connected with the shore by a narrow causeway of similar formation. Such platforms must have been of considerable extent, for the Paeonians lived there with their families and horses. Their food consisted largely of the fish which the lake produced in abundance. In rude and unsettled times, such insular sites afforded safe retreats, all communication with the mainland being cut off, except by boats, or by such wooden bridges as could be easily removed. The Swiss lake-dwellings seem first to have attracted attention during the dry winter of 1853-54, when the lakes and rivers sank lower than had ever been previously known, and when the inhabitants of Meilen, on the Lake of Zurich, resolved to raise the level of some ground and turn it into land, by throwing mud upon it obtained by dredging in the adjoining shallow water. During these dredging operations they discovered a number of wooden piles deeply driven into the bed of the lake, and among them a great many hammers, axes, celts, and other instruments. All these belonged to the stone period with two exceptions, namely, an armlet of thin brass wire, and a small bronze hatchet. Fragments of rude pottery fashioned by the hand were abundant, also masses of charred wood, supposed to have formed parts of the platform on which the wooden cabins were built. Of this burnt timber, on this and other sites, subsequently explored, there was such an abundance as to lead to the conclusion that many of the settlements must have perished by fire. Herodotus has recorded that the Paeonians, above alluded to, preserved their independence during the Persian invasion, and defied the attacks of Darius by aid of the peculiar position of their dwellings. "But their safety," observes Mr. Wylie,* "was probably owing to their living in the middle of the lake, (Greek) en mese te limne, whereas the ancient Swiss settlers were compelled by the rapidly increasing depth of the water near the margins of their lakes to construct their habitations at a short distance from the shore, within easy bowshot of the land, and therefore not out of reach of fiery projectiles, against which thatched roofs and wooden walls could present but a poor defence." (* W.M. Wylie "Archaeologia" volume 38 1859, a valuable paper on the Swiss and Irish lake-habitations.) To these circumstances and to accidental fires we are probably indebted for the frequent preservation, in the mud around the site of the old settlements, of the most precious tools and works of art, such as would never have been thrown into the Danish "kitchen-middens," which have been aptly compared to a modern dusthole. Dr. Ferdinand Keller of Zurich has drawn up a series of most instructive memoirs, illustrated with well-executed plates, of the treasures in stone, bronze, and bone brought to light in these subaqueous repositories, and has given an ideal restoration of part of one of the old villages (see Plate 1 above),* such as he conceives may have existed on the lakes of Zurich and Bienne. (*Keller "Pfahlbauten, Antiquarische Gesellschaft in Zurich" Bd. 12 and 13 1858-1861. In the fifth number of the "Natural History Review" January 9, 1862, Mr. Lubbock has published an excellent account of the works of the Swiss writers on their lake-habitations.) In this view, however, he has not simply trusted to his imagination, but has availed himself of a sketch published by M. Dumont d'Urville, of similar habitations of the Papuans in New Guinea in the Bay of Dorei. It is also stated by Dr. Keller, that on the River Limmat, near Zurich, so late as the last century, there were several fishing-huts constructed on this same plan.* (* Keller "Pfahlbauten, Antiquarische Gesellschaft in Zurich" Bd. 9 page 81 note.) It will be remarked that one of the cabins is represented as circular. That such was the form of many in Switzerland is inferred from the shape of pieces of clay which lined the interior, and which owe their preservation apparently to their having been hardened by fire when the village was burnt. In the sketch (Plate 1), some fishing-nets are seen spread out to dry on the wooden platform. The Swiss archaeologist has found abundant evidence of fishing-gear, consisting of pieces of cord, hooks, and stones used as weights. A canoe also is introduced, such as are occasionally met with. One of these, made of the trunk of a single tree, fifty feet long and three and a half feet wide, was found capsized at the bottom of the Lake of Bienne. It appears to have been laden with stones, such as were used to raise the foundation of some of the artificial islands. It is believed that as many as 300 wooden huts were sometimes comprised in one settlement, and that they may have contained about 1000 inhabitants. At Wangen, M. Lohle has calculated that 40,000 piles were used, probably not all planted at one time nor by one generation. Among the works of great merit devoted specially to a description of the Swiss lake-habitations is that of M. Troyon, published in 1860.* (* "Sur les Habitations lacustres.") The number of sites which he and other authors have already enumerated in Switzerland is truly wonderful. They occur on the large lakes of Constance, Zurich, Geneva, and Neufchatel, and on most of the smaller ones. Some are exclusively of the stone age, others of the bronze period. Of these last more than twenty are spoken of on the Lake of Geneva alone, more than forty on that of Neufchatel, and twenty on the small Lake of Bienne. One of the sites first studied by the Swiss antiquaries was the small lake of Moosseedorf, near Berne, where implements of stone, horn, and bone, but none of metal, were obtained. Although the flint here employed must have come from a distance (probably from the south of France), the chippings of the material are in such profusion as to imply that there was a manufactory of implements on the spot. Here also, as in several other settlements, hatchets and wedges of jade have been observed of a kind said not to occur in Switzerland or the adjoining parts of Europe, and which some mineralogists would fain derive from the East; amber also, which, it is supposed, was imported from the shores of the Baltic. At Wangen near Stein, on the Lake of Constance, another of the most ancient of the lake-dwellings, hatchets of serpentine and greenstone, and arrow-heads of quartz have been met with. Here also remains of a kind of cloth, supposed to be of flax, not woven but plaited, have been detected. Professor Heer has recognised lumps of carbonised wheat, Triticum vulgare, and grains of another kind, T. dicoccum, and barley, Hordeum distichum, and flat round cakes of bread; and at Robbenhausen and elsewhere Hordeum hexastichum in fine ears, the same kind of barley which is found associated with Egyptian mummies, showing clearly that in the stone period the lake-dwellers cultivated all these cereals, besides having domesticated the dog, the ox, the sheep, and the goat. Carbonised apples and pears of small size, such as still grow in the Swiss forests, stones of the wild plum, seeds of the raspberry and blackberry, and beech-nuts, also occur in the mud, and hazel-nuts in great plenty. Near Morges, on the Lake of Geneva, a settlement of the bronze period, no less than forty hatchets of that metal have been dredged up, and in many other localities the number and variety of weapons and utensils discovered, in a fine state of preservation, is truly astonishing. It is remarkable that as yet all the settlements of the bronze period are confined to Western and Central Switzerland. In the more eastern lakes those of the stone period alone have as yet been discovered. The tools, ornaments, and pottery of the bronze period in Switzerland bear a close resemblance to those of corresponding age in Denmark, attesting the wide spread of a uniform civilisation over Central Europe at that era. In some few of the Swiss aquatic stations a mixture of bronze and iron implements has been observed, but no coins. At Tiefenau, near Berne, in ground supposed to have been a battle-field, coins and medals of bronze and silver, struck at Marseilles, and of Greek manufacture, and iron swords, have been found, all belonging to the first and pre-Roman division of the age of iron. In the settlements of the bronze era the wooden piles are not so much decayed as those of the stone period; the latter having wasted down quite to the level of the mud, whereas the piles of the bronze age (as in the Lake of Bienne, for example) still project above it. Professor Rutimeyer of Basle, well-known to palaeontologists as the author of several important memoirs on fossil vertebrata, has recently published a scientific description of great interest of the animal remains dredged up at various stations where they had been embedded for ages in the mud into which the piles were driven.* (* "Die Fauna der Pfahlbauten in der Schweiz" Basel 1861.) These bones bear the same relation to the primitive inhabitants of Switzerland and some of their immediate successors as do the contents of the Danish "kitchen-middens" to the ancient fishing and hunting tribes who lived on the shores of the Baltic. The list of wild mammalia enumerated in this excellent treatise contains no less than twenty-four species, exclusive of several domesticated ones: besides which there are eighteen species of birds, the wild swan, goose, and two species of ducks being among them; also three reptiles, including the eatable frog and freshwater tortoise; and lastly, nine species of freshwater fish. All these (amounting to fifty-four species) are with one exception still living in Europe. The exception is the wild bull (Bos primigenius), which, as before stated, survived in historical times. The following are the mammalia alluded to:--The bear (Ursus arctos), the badger, the common marten, the polecat, the ermine, the weasel, the otter, wolf, fox, wild cat, hedgehog, squirrel, field-mouse (Mus sylvaticus), hare, beaver, hog (comprising two races, namely, the wild boar and swamp-hog), the stag (Cervus elaphus), the roe-deer, the fallow-deer, the elk, the steinbock (Capra ibex), the chamois, the Lithuanian bison, and the wild bull. The domesticated species comprise the dog, horse, ass, pig, goat, sheep, and several bovine races. The greater number, if not all, of these animals served for food, and all the bones which contained marrow have been split open in the same way as the corresponding ones found in the shell-mounds of Denmark before mentioned. The bones both of the wild bull and the bison are invariably split in this manner. As a rule, the lower jaws with teeth occur in greater abundance than any other parts of the skeleton--a circumstance which, geologists know, holds good in regard to fossil mammalia of all periods. As yet the reindeer is missing in the Swiss lake-settlements as in the Danish "kitchen-middens," although this animal in more ancient times ranged over France, together with the mammoth, as far south as the Pyrenees. A careful comparison of the bones from different sites has shown that in settlements such as Wangen and Moosseedorf, belonging to the earliest age of stone, when the habits of the hunter state predominated over those of the pastoral, venison, or the flesh of the stag and roe, was more eaten than the flesh of the domestic cattle and sheep. This was afterwards reversed in the later stone period and in the age of bronze. At that later period also the tame pig, which is wanting in some of the oldest stations, had replaced the wild boar as a common article of food. In the beginning of the age of stone, in Switzerland, the goats outnumbered the sheep, but towards the close of the same period the sheep were more abundant than the goats. The fox in the first era was very common, but it nearly disappears in the bronze age, during which period a large hunting-dog, supposed to have been imported into Switzerland from some foreign country, becomes the chief representative of the canine genus. A single fragment of the bone of a hare (Lepus timidus) has been found at Moosseedorf. The almost universal absence of this quadruped is supposed to imply that the Swiss lake-dwellers were prevented from eating that animal by the same superstition which now prevails among the Laplanders, and which Julius Caesar found in full force amongst the ancient Britons.* (* "Commentaries" lib 5 chapter 12.) That the lake-dwellers should have fed so largely on the fox, while they abstained from touching the hare, establishes, says Rutimeyer, a singular contrast between their tastes and ours. Even in the earliest settlements, as already hinted, several domesticated animals occur, namely, the ox, sheep, goat, and dog. Of the three last, each was represented by one race only; but there were two races of cattle, the most common being of small size, and called by Rutimeyer Bos brachyceros (Bos longifrons, Owen), or the marsh cow, the other derived from the wild bull; though, as no skull has yet been discovered, this identification is not so certain as could be wished. It is, however, beyond question that at a later era, namely, towards the close of the stone and beginning of the bronze period, the lake-dwellers had succeeded in taming that formidable brute the Bos primigenius, the Urus of Caesar, which he described as very fierce, swift, and strong, and scarcely inferior to the elephant in size. In a tame state its bones were somewhat less massive and heavy, and its horns were somewhat smaller than in wild individuals. Still in its domesticated form, it rivalled in dimensions the largest living cattle, those of Friesland, in North Holland, for example. When most abundant, as at Concise on the Lake of Neufchatel, it had nearly superseded the smaller race, Bos brachyceros, and was accompanied there for a short time by a third bovine variety, called Bos trochoceros, an Italian race, supposed to have been imported from the southern side of the Alps. (Caesar "Commentaries" lib 5 chapter 12.) This last-mentioned race, however, seems only to have lasted for a short time in Switzerland. The wild bull (Bos primigenius) is supposed to have flourished for a while in a wild and tame state, just as now in Europe the domestic pig co-exists with the wild boar; and Rutimeyer agrees with Cuvier and Bell,* in considering our larger domestic cattle of northern Europe as the descendants of this wild bull, an opinion which Owen disputes.** (* "British Quadrupeds" page 415.) (** "British Fossil Mammal." page 500.) In the later division of the stone period, there were two tame races of the pig, according to Rutimeyer; one large, and derived from the wild boar, the other smaller, called the "marsh-hog," or Sus scrofa palustris. It may be asked how the osteologist can distinguish the tame from the wild races of the same species by their skeletons alone. Among other characters, the diminished thickness of the bones and the comparative smallness of the ridges, which afford attachment to the muscles, are relied on; also the smaller dimensions of the tusks in the boar, and of the whole jaw and skull; and, in like manner, the diminished size of the horns of the bull and other modifications, which are the effects of a regular supply of food, and the absence of all necessity of exerting their activity and strength to obtain subsistence and defend themselves against their enemies. A middle-sized race of dogs continued unaltered throughout the whole of the stone period; but the people of the bronze age possessed a larger hunting-dog, and with it a small horse, of which genus very few traces have been detected in the earlier settlements--a single tooth, for example, at Wangen, and only one or two bones at two or three other places. In passing from the oldest to the most modern sites, the extirpation of the elk and beaver, and the gradual reduction in numbers of the bear, stag, roe, and freshwater tortoise are distinctly perceptible. The aurochs, or Lithuanian bison, appears to have died out in Switzerland about the time when weapons of bronze came into use. It is only in a few of the most modern lake-dwellings, such as Noville and Chavannes in the Canton de Vaud (which the antiquaries refer to the sixth century), that some traces are observable of the domestic cat, as well as of a sheep with crooked horns and with them bones of the domestic fowl. After the sixth century, no extinction of any wild quadruped nor introduction of any tame one appears to have taken place, but the fauna was still modified by the wild species continuing to diminish in number and the tame ones to become more diversified by breeding and crossing, especially in the case of the dog, horse, and sheep. On the whole, however, the divergence of the domestic races from their aboriginal wild types, as exemplified at Wangen and Moosseedorf, is confined, according to Professor Rutimeyer, within narrow limits. As to the goat, it has remained nearly constant and true to its pristine form, and the small race of goat-horned sheep still lingers in some alpine valleys in the Upper Rhine; and in the same region a race of pigs, corresponding to the domesticated variety of Sus scrofa palustris, may still be seen. Amidst all this profusion of animal remains extremely few bones of Man have been discovered; and only one skull, dredged up from Meilen, on the Lake of Zurich, of the early stone period, seems as yet to have been carefully examined. Respecting this specimen, Professor His observes that it exhibits, instead of the small and rounded form proper to the Danish peat-mosses, a type much more like that now prevailing in Switzerland, which is intermediate between the long-headed and short-headed form. (Rutimeyer "Die Fauna der Pfahlbauten in der Schweiz" page 181.) So far, therefore, as we can draw safe conclusions from a single specimen, there has been no marked change of race in the human population of Switzerland during the periods above considered. It is still a question whether any of these subaqueous repositories of ancient relics in Switzerland go back so far in time as the kitchen-middens of Denmark, for in these last there are no domesticated animals except the dog, and no signs of the cultivation of wheat or barley; whereas we have seen that, in one of the oldest of the Swiss settlements, at Wangen, no less than three cereals make their appearance, with four kinds of domestic animals. Yet there is no small risk of error in speculating on the relative claims to antiquity of such ancient tribes, for some of them may have remained isolated for ages and stationary in their habits, while others advanced and improved. We know that nations, both before and after the introduction of metals, may continue in very different stages of civilisation, even after commercial intercourse has been established between them, and where they are separated by a less distance than that which divides the Alps from the Baltic. The attempts of the Swiss geologists and archaeologists to estimate definitely in years the antiquity of the bronze and stone periods, although as yet confessedly imperfect, deserve notice, and appear to me to be full of promise. The most elaborate calculation is that made by M. Morlot, respecting the delta of the Tiniere, a torrent which flows into the Lake of Geneva near Villeneuve. This small delta, to which the stream is annually making additions, is composed of gravel and sand. Its shape is that of a flattened cone, and its internal structure has of late been laid open to view in a railway cutting 1000 feet long and 32 feet deep. The regularity of its structure throughout implies that it has been formed very gradually, and by the uniform action of the same causes. Three layers of vegetable soil, each of which must at one time have formed the surface of the cone, have been cut through at different depths. The first of these was traced over a surface of 15,000 square feet, having an average thickness of 5 inches, and being about 4 feet below the present surface of the cone. This upper layer belonged to the Roman period, and contained Roman tiles and a coin. The second layer, followed over a surface of 25,000 square feet, was 6 inches thick, and lay at a depth of 10 feet. In it were found fragments of unvarnished pottery and a pair of tweezers in bronze, indicating the bronze epoch. The third layer, followed for 35,000 square feet, was 6 or 7 inches thick and 19 feet deep. In it were fragments of rude pottery, pieces of charcoal, broken bones, and a human skeleton having a small, round and very thick skull. M. Morlot, assuming the Roman period to represent an antiquity of from sixteen to eighteen centuries, assigns to the bronze age a date of between 3000 and 4000 years, and to the oldest layer, that of the stone period, an age of from 5000 to 7000 years. Another calculation has been made by M. Troyon to obtain the approximate date of the remains of an ancient settlement built on piles and preserved in a peat-bog at Chamblon, near Yverdun, on the Lake of Neufchatel. The site of the ancient Roman town of Eburodunum (Yverdun), once on the borders of the lake, and between which and the shore there now intervenes a zone of newly-gained dry land, 2500 feet in breadth, shows the rate at which the bed of the lake has been filled up with river sediment in fifteen centuries. Assuming the lake to have retreated at the same rate before the Roman period, the pile-works of Chamblon, which are of the bronze period, must be at the least 3300 years old. For the third calculation, communicated to me by M. Morlot, we are indebted to M. Victor Gillieron, of Neuveville, on the Lake of Bienne. It relates to the age of a pile-dwelling, the mammalian bones of which are considered by M. Rutimeyer to indicate the earliest portion of the stone period of Switzerland, and to correspond in age with the settlement of Moosseedorf. The piles in question occur at the Pont de Thiele, between the lakes of Bienne and Neufchatel. The old convent of St. Jean, founded 750 years ago, and built originally on the margin of the Lake of Bienne, is now at a considerable distance from the shore, and affords a measure of the rate of the gain of land in seven centuries and a half. Assuming that a similar rate of the conversion of water into marshy land prevailed antecedently, we should require an addition of sixty centuries for the growth of the morass intervening between the convent and the aquatic dwelling of Pont de Thiele, in all 6750 years. M. Morlot, after examining the ground, thinks it highly probable that the shape of the bottom on which the morass rests is uniform; but this important point has not yet been tested by boring. The result, if confirmed, would agree exceedingly well with the chronological computation before mentioned of the age of the stone period of Tiniere. As I have not myself visited Switzerland since these chronological speculations were first hazarded, I am unable to enter critically into a discussion of the objections which have been raised to the two first of them, or to decide on the merits of the explanations offered in reply. IRISH LAKE-DWELLINGS OR CRANNOGES. The lake-dwellings of the British isles, although not explored as yet with scientific zeal, as those of Switzerland have been in the last ten years, are yet known to be very numerous, and when carefully examined will not fail to throw great light on the history of the bronze and stone periods. In the lakes of Ireland alone, no less than forty-six examples of artificial islands, called crannoges, have been discovered. They occur in Leitrim, Roscommon, Cavan, Down, Monaghan, Limerick, Meath, King's County, and Tyrone.* (* W.M. Wylie "Archaeologia" volume 38 1859 page 8.) One class of these "stockaded islands," as they have been sometimes called, was formed, according to Mr. Digby Wyatt, by placing horizontal oak beams at the bottom of the lake, into which oak posts, from 6 to 8 feet high, were mortised, and held together by cross beams, till a circular enclosure was obtained. A space of 520 feet diameter, thus enclosed at Lagore, was divided into sundry timbered compartments, which were found filled up with mud or earth, from which were taken "vast quantities of the bones of oxen, swine, deer, goats, sheep, dogs, foxes, horses, and asses." All these were discovered beneath 16 feet of bog, and were used for manure; but specimens of them are said to be preserved in the museum of the Royal Irish Academy. From the same spot were obtained a great collection of antiquities, which, according to Lord Talbot de Malahide and Mr. Wylie, were referable to the ages of stone, bronze, and iron.* (* W.M. Wylie "Archaeologia" volume 38 1859 page 8, who cites "Archaeological Journal" volume 6 page 101.) In Ardekillin Lake, in Roscommon, an islet of an oval form was observed, made of a layer of stones resting on logs of timber. Round this artificial islet or crannoge thus formed was a stone wall raised on oak piles. A careful description has been put on record by Captain Mudge, R.N., of a curious log-cabin discovered by him in 1833 in Drumkellin bog, in Donegal, at a depth of 14 feet from the surface. It was 12 feet square and 9 feet high, being divided into two stories each 4 feet high. The planking was of oak split with wedges of stone, one of which was found in the building. The roof was flat. A staked enclosure had been raised round the cabin, and remains of other similar huts adjoining were seen but not explored. A stone celt, found in the interior of the hut, and a piece of leather sandal, also an arrow-head of flint, and in the bog close at hand a wooden sword, give evidence of the remote antiquity of this building, which may be taken as a type of the early dwellings on the Crannoge islands. "The whole structure," says Captain Mudge, "was wrought with the rudest kind of implements, and the labour bestowed on it must have been immense. The wood of the mortises was more bruised than cut, as if by a blunt stone chisel."* (* Mudge "Archaeologia" volume 26.) Such a chisel lay on the floor of the hut, and by comparing it with the marks of the tool used in forming the mortises, they were found "to correspond exactly, even to the slight curved exterior of the chisel; but the logs had been hewn by a larger instrument, in the shape of an axe. On the floor of the dwelling lay a slab of freestone, 3 feet long and 14 inches thick, in the centre of which was a small pit three quarters of an inch deep, which had been chiselled out. This is presumed to have been used for holding nuts to be cracked by means of one of the round shingle stones, also found there, which had served as a hammer. Some entire hazel-nuts and a great quantity of broken shells were strewed about the floor." The foundations of the house were made of fine sand, such as is found with shingle on the seashore about 2 miles distant. Below the layer of sand the bog or peat was ascertained, on probing it with an instrument, to be at least 15 feet thick. Although the interior of the building when discovered was full of "bog" or peaty matter, it seems when inhabited to have been surrounded by growing trees, some of the trunks and roots of which are still preserved in their natural position. The depth of overlying peat affords no safe criterion for calculating the age of the cabin or village, for I have shown in the "Principles of Geology" that both in England and Ireland, within historical times, bogs have burst and sent forth great volumes of black mud, which has been known to creep over the country at a slow pace, flowing somewhat at the rate of ordinary lava-currents, and sometimes overwhelming woods and cottages, and leaving a deposit upon them of bog-earth 15 feet thick. None of these Irish lake-dwellings were built, like those of Helvetia, on platforms supported by piles deeply driven into the mud. "The Crannoge system of Ireland seems," says Mr. Wylie, "well nigh without a parallel in Swiss waters." CHAPTER 3. -- FOSSIL HUMAN REMAINS AND WORKS OF ART OF THE RECENT PERIOD--CONTINUED. Delta and Alluvial Plain of the Nile. Burnt Bricks in Egypt before the Roman Era. Borings in 1851-54. Ancient Mounds of the Valley of the Ohio. Their Antiquity. Sepulchral Mound at Santos in Brazil. Delta of the Mississippi. Ancient Human Remains in Coral Reefs of Florida. Changes in Physical Geography in the Human Period. Buried Canoes in Marine Strata near Glasgow. Upheaval since the Roman Occupation of the Shores of the Firth of Forth. Fossil Whales near Stirling. Upraised Marine Strata of Sweden on Shores of the Baltic and the Ocean. Attempts to compute their Age. DELTA AND ALLUVIAL PLAIN OF THE NILE. Some new facts of high interest illustrating the geology of the alluvial land of Egypt were brought to light between the years 1851 and 1854, in consequence of investigations suggested to the Royal Society by Mr. Leonard Horner, and which were partly carried out at the expense of the Society. The practical part of the undertaking was entrusted by Mr. Horner to an Armenian officer of engineers, Hekekyan Bey, who had for many years pursued his scientific studies in England, and was in every way highly qualified for the task. It was soon found that to obtain the required information respecting the nature, depth, and contents of the Nile mud in various parts of the valley, a larger outlay was called for than had been originally contemplated. This expense the late viceroy, Abbas Pasha, munificently undertook to defray out of his treasury, and his successor, after his death, continued the operations with the same princely liberality. Several engineers and a body of sixty workmen were employed under the superintendence of Hekekyan Bey, men inured to the climate and able to carry on the sinking of shafts and borings during the hot months, after the waters of the Nile had subsided, and in a season which would have been fatal to Europeans. The results of chief importance arising out of this inquiry were obtained from two sets of shafts and borings sunk at intervals in lines crossing the great valley from east to west. One of these consisted of no fewer than fifty-one pits and artesian borings, made where the valley is 16 miles wide from side to side between the Arabian and Libyan deserts, in the latitude of Heliopolis, about 8 miles above the apex of the delta. The other line of borings and pits, twenty-seven in number, was in the parallel of Memphis, where the valley is only five miles broad. Everywhere in these sections the sediment passed through was similar in composition to the ordinary Nile mud of the present day, except near the margin of the valley, where thin layers of quartzose sand, such as is sometimes blown from the adjacent desert by violent winds, were observed to alternate with the loam. A remarkable absence of lamination and stratification was observed almost universally in the sediment brought up from all points except where the sandy layers above alluded to occurred. Mr. Horner attributes this want of all indication of successive deposition to the extreme thinness of the film of matter which is thrown down annually on the great alluvial plain during the season of inundation. The tenuity of this layer must indeed be extreme, if the French engineers are tolerably correct in their estimate of the amount of sediment formed in a century, which they suppose not to exceed on the average 5 inches. When the waters subside, this thin layer of new soil, exposed to a hot sun, dries rapidly, and clouds of dust are raised by the winds. The superficial deposit, moreover, is disturbed almost everywhere by agricultural labours, and even were this not the case, the action of worms, insects, and the roots of plants would suffice to confound together the deposits of two successive years. All the remains of organic bodies, such as land-shells, and the bones of quadrupeds, found during the excavations belonged to living species. Bones of the ox, hog, dog, dromedary and ass were not uncommon, but no vestiges of extinct mammalia. No marine shells were anywhere detected; but this was to be expected, as the borings, though they sometimes reached as low as the level of the Mediterranean, were never carried down below it--a circumstance much to be regretted, since where artesian borings have been made in deltas, as in those of the Po and Ganges, to the depth of several hundred feet below the sea level it has been found, contrary to expectation, that the deposits passed through were fluviatile throughout, implying, probably, that a general subsidence of those deltas and alluvial formations has taken place. Whether there has been in like manner a sinking of the land in Egypt, we have as yet no means of proving; but Sir Gardner Wilkinson infers it from the position in the delta on the shore near Alexandria of the tombs commonly called Cleopatra's Baths, which cannot, he says, have been originally built so as to be exposed to the sea which now fills them, but must have stood on land above the level of the Mediterranean. The same author adduces, as additional signs of subsidence, some ruined towns, now half under water, in the Lake Menzaleh, and channels of ancient arms of the Nile submerged with their banks beneath the waters of that same lagoon. In some instances, the excavations made under the superintendence of Hekekyan Bey were on a large scale for the first 16 or 24 feet, in which cases jars, vases, pots and a small human figure in burnt clay, a copper knife, and other entire articles were dug up; but when water soaking through from the Nile was reached the boring instrument used was too small to allow of more than fragments of works of art being brought up. Pieces of burnt brick and pottery were extracted almost everywhere, and from all depths, even where they sank 60 feet below the surface towards the central parts of the valley. In none of these cases did they get to the bottom of the alluvial soil. It has been objected, among other criticisms, that the Arabs can always find whatever their employers desire to obtain. Even those who are too well acquainted with the sagacity and energy of Hekekyan Bey to suspect him of having been deceived, have suggested that the artificial objects might have fallen into old wells which had been filled up. This notion is inadmissible for many reasons. Of the ninety-five shafts and borings, seventy or more were made far from the sites of towns or villages; and allowing that every field may once have had its well, there would be but small chance of the borings striking upon the site even of a small number of them in seventy experiments. Others have suggested that the Nile may have wandered over the whole valley, undermining its banks on one side and filling up old channels on the other. It has also been asked whether the delta with the numerous shifting arms of the river may not once have been at every point where the auger pierced.* (* For a detailed account of these sections, see Mr. Horner's paper in the "Philosophical Transactions" for 1855 to 1858.) To all these objections there are two obvious answers:--First, in historical times the Nile has on the whole been very stationary, and has not shifted its position in the valley; secondly, if the mud pierced through had been thrown down by the river in ancient channels, it would have been stratified, and would not have corresponded so closely with inundation mud, we learn from Captain Newbold that he observed in some excavations in the great plain alternations of sand and clay, such as are seen in the modern banks of the Nile; but in the borings made by Hekekyan Bey, such stratification seems scarcely in any case to have been detected. The great aim of the criticisms above enumerated has been to get rid of the supposed anomaly of finding burnt brick and pottery at depths and places which would give them claim to an antiquity far exceeding that of the Roman domination in Egypt. For until the time of the Romans, it is said, no clay was burnt into bricks in the valley of the Nile. But a distinguished antiquary, Mr. S. Birch, assures me that this notion is altogether erroneous, and that he has under his charge in the British Museum, first, a small rectangular baked brick, which came from a Theban tomb which bears the name of Thothmes, a superintendent of the granaries of the god Amen Ra, the style of art, inscription, and name, showing that it is as old as the 18th dynasty (about 1450 B.C.); secondly, a brick bearing an inscription, partly obliterated, but ending with the words "of the temple of Amen Ra." This brick, decidedly long anterior to the Roman dominion, is referred conjecturally, by Mr. Birch, to the 19th dynasty, or 1300 B.C. Sir Gardner Wilkinson has also in his possession pieces of mortar, which he took from each of the three great pyramids, in which bits of broken pottery and of burnt clay or brick are embedded. M. Girard, of the French expedition to Egypt, supposed the average rate of the increase of Nile mud on the plain between Assouan and Cairo to be five English inches in a century. This conclusion, according to Mr. Horner, is very vague, and founded on insufficient data; the amount of matter thrown down by the waters in different parts of the plain varying so much that to strike an average with any approach to accuracy must be most difficult. Were we to assume six inches in a century, the burnt brick met with at a depth of 60 feet would be 12,000 years old. Another fragment of red brick was found by Linant Bey, in a boring 72 feet deep, being 2 or 3 feet below the level of the Mediterranean, in the parallel of the apex of the delta, 200 metres distant from the river, on the Libyan side of the Rosetta branch.* (* Horner "Philosophical Transactions" 1858.) M. Rosiere, in the great French work on Egypt, has estimated the mean rate of deposit of sediment in the delta at 2 1/4 inches in a century;* were we to take 2 1/2 inches, a work of art 72 feet deep must have been buried more than 30,000 years ago. (* Description de l'Egypte "Histoire Naturelle" tome 2 page 494.) But if the boring of Linant Bey was made where an arm of the river had been silted up at a time when the apex of the delta was somewhat farther south, or more distant from the sea than now, the brick in question might be comparatively very modern. The experiments instituted by Mr. Horner at the pedestal of the fallen statue of King Rameses at Memphis, in the hope of obtaining an accurate chronometric scale for testing the age of a given thickness of Nile sediment, are held by some experienced Egyptologists not to be satisfactory, on the ground of the uncertainty of the rate of deposit accumulated at that locality. The point sought to be determined was the exact amount of Nile mud which had accumulated there since the time when that statue is supposed by some antiquaries to have been erected. Could we have obtained possession of such a measure, the rate of deposition might be judged of, approximately at least, whenever similar mud was observed in other places, or below the foundations of those same monuments. But the ancient Egyptians are known to have been in the habit of enclosing with embankments the areas on which they erected temples, statues, and obelisks, so as to exclude the waters of the Nile; and the point of time to be ascertained, in every case where we find a monument buried to a certain depth in mud, as at Memphis and Heliopolis, is the era when the city fell into such decay that the ancient embankments were neglected, and the river allowed to inundate the site of the temple, obelisk, or statue. Even if we knew the date of the abandonment of such embankments, the enclosed areas would not afford a favourable opportunity for ascertaining the average rate of deposit in the alluvial plain; for Herodotus tells us that in his time those spots from which the Nile waters had been shut out for centuries appeared sunk, and could be looked down into from the surrounding grounds, which had been raised by the gradual accumulation over them of sediment annually thrown down. If the waters at length should break into such depressions, they must at first carry with them into the enclosure much mud washed from the steep surrounding banks, so that a greater quantity would be deposited in a few years than perhaps in as many centuries on the great plain outside the depressed area, where no such disturbing causes intervened. ANCIENT MOUNDS OF THE VALLEY OF THE OHIO. As I have already given several European examples of monuments of prehistoric date belonging to the Recent period, I will now turn to the American continent. Before the scientific investigation by Messrs. Squier and Davis of the "Ancient Monuments of the Mississippi Valley",* no one suspected that the plains of that river had been occupied, for ages before the French and British colonists settled there, by a nation of older date and more advanced in the arts than the Red Indians whom the Europeans found there. (* "Smithsonian Contributions" volume 1 1847.) There are hundreds of large mounds in the basin of the Mississippi, and especially in the valleys of the Ohio and its tributaries, which have served, some of them for temples, others for outlook or defence, and others for sepulture. The unknown people by whom they were constructed, judging by the form of several skulls dug out of the burial-places, were of the Mexican or Toltec race. Some of the earthworks are on so grand a scale as to embrace areas of 50 or 100 acres within a simple enclosure, and the solid contents of one mould are estimated at 20 million of cubic feet, so that four of them would be more than equal in bulk to the Great Pyramid of Egypt, which comprises 75 million. From several of these repositories pottery and ornamental sculpture have been taken, and various articles in silver and copper, also stone weapons, some composed of hornstone unpolished, and much resembling in shape some ancient flint implements found near Amiens and other places in Europe, to be alluded to in the sequel. It is clear that the Ohio mound-builders had commercial intercourse with the natives of distant regions, for among the buried articles some are made of native copper from Lake Superior, and there are also found mica from the Alleghenies, sea-shells from the Gulf of Mexico, and obsidian from the Mexican mountains. The extraordinary number of the mounds implies a long period, during which a settled agricultural population had made considerable progress in civilisation, so as to require large temples for their religious rites, and extensive fortifications to protect them from their enemies. The mounds were almost all confined to fertile valleys or alluvial plains, and some at least are so ancient that rivers have had time since their construction to encroach on the lower terraces which support them, and again to recede for the distance of nearly a mile, after having undermined and destroyed a part of the works. When the first European settlers entered the valley of the Ohio, they found the whole region covered with an uninterrupted forest, and tenanted by the Red Indian hunter, who roamed over it without any fixed abode, or any traditionary connection with his more civilised predecessors. The only positive data as yet obtained for calculating the minimum of time which must have elapsed since the mounds were abandoned, have been derived from the age and nature of the trees found growing on some of these earthworks. When I visited Marietta in 1842, Dr. Hildreth took me to one of the mounds, and showed me where he had seen a tree growing on it, the trunk of which when cut down displayed eight hundred rings of annual growth.* (* Lyell's "Travels in North America" volume 2 page 29.) But the late General Harrison, President in 1841 of the United States, who was well skilled in woodcraft, has remarked, in a memoir on this subject, that several generations of trees must have lived and died before the mounds could have been overspread with that variety of species which they supported when the white man first beheld them, for the number and kinds of trees were precisely the same as those which distinguished the surrounding forest. "We may be sure," observed Harrison, "that no trees were allowed to grow so long as the earthworks were in use; and when they were forsaken, the ground, like all newly cleared land in Ohio, would for a time be monopolised by one or two species of tree, such as the yellow locust and the black or white walnut. When the individuals which were the first to get possession of the ground had died out one after the other, they would in many cases, instead of being replaced by the same species, be succeeded (by virtue of the law which makes a rotation of crops profitable in agriculture) by other kinds, till at last, after a great number of centuries (several thousand years, perhaps), that remarkable diversity of species characteristic of North America, and far exceeding what is seen in European forests, would be established." MOUNDS OF SANTOS IN BRAZIL. I will next say a few words respecting certain human bones embedded in a solid rock at Santos in Brazil, to which I called attention in my "Travels in North America" in 1842.* (* Volume 1 page 200.) I then imagined the deposit containing them to be of submarine origin--an opinion which I have long ceased to entertain. We learn from a memoir of Dr. Meigs that the River Santos has undermined a large mound, 14 feet in height, and about 3 acres in area, covered with trees, near the town of St. Paul, and has exposed to view many skeletons, all inclined at angles between 20 and 25 degrees, and all placed in a similar east and west position.* (* Meigs "Transactions of the American Philosophical Society" 1828 page 285.) Seeing, in the Museum of Philadelphia, fragments of the calcareous stone or tufa from this spot, containing a human skull with teeth, and in the same matrix, oysters with serpulae attached, I at first concluded that the whole deposit had been formed beneath the waters of the sea, or at least, that it had been submerged after its origin, and again upheaved; also, that there had been time since its emergence for the growth on it of a forest of large trees. But after reading again, with more care, the original memoir of Dr. Meigs, I cannot doubt that the shells, like those of eatable kinds, so often accumulated in the mounds of the North American Indians not far from the sea, may have been brought to the place and heaped up with other materials at the time when the bodies were buried. Subsequently, the whole artificial earthwork, with its shells and skeletons, may have been bound together into a solid stone by the infiltration of carbonate of lime, and the mound may therefore be of no higher antiquity than some of those above alluded to on the Ohio, which, as we have seen, have in like manner been exposed in the course of ages to the encroachments and undermining action of rivers. DELTA OF THE MISSISSIPPI. I have shown in my "Travels in North America" that the deposits forming the delta and alluvial plain of the Mississippi consist of sedimentary matter, extending over an area of 30,000 square miles, and known in some parts to be several hundred feet deep. Although we cannot estimate correctly how many years it may have required for the river to bring down from the upper country so large a quantity of earthy matter--the data for such a computation being as yet incomplete--we may still approximate to a minimum of the time which such an operation must have taken, by ascertaining experimentally the annual discharge of water by the Mississippi, and the mean annual amount of solid matter contained in its waters. The lowest estimate of the time required would lead us to assign a high antiquity, amounting to many tens of thousands of years (probably more than 100,000) to the existing delta. Whether all or how much of this formation may belong to the recent period, as above defined, I cannot pretend to decide, but in one part of the modern delta near New Orleans, a large excavation has been made for gas-works, where a succession of beds, almost wholly made up of vegetable matter, has been passed through, such as we now see forming in the cypress swamps of the neighbourhood, where the deciduous cypress (Taxodium distichum), with its strong and spreading roots, plays a conspicuous part. In this excavation, at the depth of sixteen feet from the surface, beneath four buried forests superimposed one upon the other, the workmen are stated by Dr. B. Dowler to have found some charcoal and a human skeleton, the cranium of which is said to belong to the aboriginal type of the Red Indian race. As the discovery in question had not been made when I saw the excavation in progress at the gas-works in 1846, I cannot form an opinion as to the value of the chronological calculations which have led Dr. Dowler to ascribe to this skeleton an antiquity of 50,000 years. In several sections, both natural in the banks of the Mississippi and its numerous arms, and where artificial canals had been cut, I observed erect stumps of trees, with their roots attached, buried in strata at different heights, one over the other. I also remarked, that many cypresses which had been cut through, exhibited many hundreds of rings of annual growth, and it then struck me that nowhere in the world could the geologist enjoy a more favourable opportunity for estimating in years the duration of certain portions of the Recent epoch.* (* Dowler cited by Dr. W. Usher in Nott and Gliddon's "Types of Mankind" page 352.) CORAL REEFS OF FLORIDA. Professor Agassiz has described a low portion of the peninsula of Florida as consisting of numerous reefs of coral, which have grown in succession so as to give rise to a continual annexation of land, gained gradually from the sea in a southerly direction. This growth is still in full activity, and assuming the rate of advance of the land to be one foot in a century, the reefs being built up from a depth of 75 feet, and that each reef has in its turn added ten miles to the coast, Professor Agassiz calculates that it has taken 135,000 years to form the southern half of this peninsula. Yet the whole is of Post-Tertiary origin, the fossil zoophytes and shells being all of the same species as those now inhabiting the neighbouring sea.* (* Agassiz in Nott and Gliddon ibid. page 352.) In a calcareous conglomerate forming part of the above-mentioned series of reefs, and supposed by Agassiz, in accordance with his mode of estimating the rate of growth of those reefs, to be about 10,000 years old, some fossil human remains were found by Count Pourtales. They consisted of jaws and teeth, with some bones of the foot. RECENT DEPOSITS OF SEAS AND LAKES. I have shown, in the "Principles of Geology," where the recent changes of the earth illustrative of geology are described at length, that the deposits accumulated at the bottom of lakes and seas within the last 4000 or 5000 years can neither be insignificant in volume or extent. They lie hidden, for the most part, from our sight; but we have opportunities of examining them at certain points where newly-gained land in the deltas of rivers has been cut through during floods, or where coral reefs are growing rapidly, or where the bed of a sea or lake has been heaved up by subterranean movements and laid dry. As examples of such changes of level by which marine deposits of the Recent period have become accessible to human observation, I have adduced the strata near Naples in which the Temple of Serapis at Pozzuoli was entombed.* (* "Principles of Geology" Index "Serapis.") These upraised strata, the highest of which are about 25 feet above the level of the sea, form a terrace skirting the eastern shore of the Bay of Baiae. They consist partly of clay, partly of volcanic matter, and contain fragments of sculpture, pottery, and the remains of buildings, together with great numbers of shells, retaining in part their colour, and of the same species as those now inhabiting the neighbouring sea. Their emergence can be proved to have taken place since the beginning of the sixteenth century. [5] In the same work, as an example of a freshwater deposit of the Recent period, I have described certain strata in Cashmere, a country where violent earthquakes, attended by alterations in the level of the ground, are frequent, in which freshwater shells of species now inhabiting the lakes and rivers of that region are embedded, together with the remains of pottery, often at the depth of fifty feet, and in which a splendid Hindoo temple has lately been discovered, and laid open to view by the removal of the lacustrine silt which had enveloped it for four or five centuries. In the same treatise it is stated that the west coast of South America, between the Andes and the Pacific, is a great theatre of earthquake movements, and that permanent upheavals of the land of several feet at a time have been experienced since the discovery of America. In various parts of the littoral region of Chile and Peru, strata have been observed enclosing shells in abundance, all agreeing specifically with those now swarming in the Pacific. In one bed of this kind, in the island of San Lorenzo, near Lima, Mr. Darwin found, at the altitude of 85 feet above the sea, pieces of cotton-thread, plaited rush, and the head of a stalk of Indian corn, the whole of which had evidently been embedded with the shells. At the same height, on the neighbouring mainland, he found other signs corroborating the opinion that the ancient bed of the sea had there also been uplifted 85 feet since the region was first peopled by the Peruvian race. But similar shelly masses are also met with at much higher elevations, at innumerable points between the Chilean and Peruvian Andes and the sea-coast, in which no human remains have as yet been observed. The preservation for an indefinite period of such perishable substances as thread is explained by the entire absence of rain in Peru. The same articles, had they been enclosed in the permeable sands of an European raised beach, or in any country where rain falls even for a small part of the year, would probably have disappeared entirely [6] In the literature of the eighteenth century, we find frequent allusion to the "era of existing continents," a period supposed to have coincided in date with the first appearance of Man upon the earth, since which event it was imagined that the relative level of the sea and land had remained stationary, no important geographical changes having occurred, except some slight additions to the deltas of rivers, or the loss of narrow strips of land where the sea had encroached upon its shores. But modern observations have tended continually to dispel this delusion, and the geologist is now convinced that at no given era of the past have the boundaries of land and sea, or the height of the one and depth of the other, or the geographical range of the species inhabiting them, whether of animals or plants, become fixed and unchangeable. Of the extent to which fluctuations have been going on since the globe had already become the dwelling-place of Man, some idea may be formed from the examples which I shall give in this and the next nine chapters. UPHEAVAL SINCE THE HUMAN PERIOD OF THE CENTRAL DISTRICT OF SCOTLAND. [7] It has long been a fact familiar to geologists, that, both on the east and west coasts of the central part of Scotland, there are lines of raised beaches, containing marine shells of the same species as those now inhabiting the neighbouring sea.* (* R. Chambers "Sea Margins" 1848 and papers by Mr. Smith of Jordan Hill "Memoirs of the Wernerian Society" volume 8 and by Mr. C. Maclaren. ) The two most marked of these littoral deposits occur at heights of about 50 and 25 feet above high-water mark, that of 50 feet being considered as the more ancient, and owing its superior elevation to a continuance of the upheaving movement. They are seen in some places to rest on the boulder clay of the glacial period, which will be described in future chapters. In those districts where large rivers, such as the Clyde, Forth, and Tay, enter the sea, the lower of the two deposits, or that of 25 feet, expands into a terrace fringing the estuaries, and varying in breadth from a few yards to several miles. Of this nature are the flat lands which occur along the margin of the Clyde at Glasgow, which consist of finely laminated sand, silt, and clay. Mr. John Buchanan, a zealous antiquary, writing in 1855, informs us that in the course of the eighty years preceding that date, no less than seventeen canoes had been dug out of this estuarine silt, and that he had personally inspected a large number of them before they were exhumed. Five of them lay buried in silt under the streets of Glasgow, one in a vertical position with the prow uppermost as if it had sunk in a storm. In the inside of it were a number of marine shells. Twelve other canoes were found about 100 yards back from the river, at the average depth of about 19 feet from the surface of the soil, or 7 feet above high-water mark; but a few of them were only 4 or 5 feet deep, and consequently more than 20 feet above the sea-level. One was sticking in the sand at an angle of 45 degrees, another had been capsized and lay bottom uppermost; all the rest were in a horizontal position, as if they had sunk in smooth water.* (* J. Buchanan "Report of the British Association" 1855 page 80; also "Glasgow, Past and Present" 1856.) Almost every one of these ancient boats was formed out of a single oak-stem, hollowed out by blunt tools, probably stone axes, aided by the action of fire; a few were cut beautifully smooth, evidently with metallic tools. Hence a gradation could be traced from a pattern of extreme rudeness to one showing great mechanical ingenuity. Two of them were built of planks, one of the two, dug up on the property of Bankton in 1853, being 18 feet in length, and very elaborately constructed. Its prow was not unlike the beak of an antique galley; its stern, formed of a triangular-shaped piece of oak, fitted in exactly like those of our day. The planks were fastened to the ribs, partly by singularly shaped oaken pins, and partly by what must have been square nails of some kind of metal; these had entirely disappeared, but some of the oaken pins remained. This boat had been upset, and was lying keel uppermost, with the prow pointing straight up the river. In one of the canoes, a beautifully polished celt or axe of greenstone was found, in the bottom of another a plug of cork, which, as Mr. Geikie remarks, "could only have come from the latitudes of Spain, Southern France, or Italy."* (* Geikie, "Quarterly Journal of the Geological Society" volume 18 1862 page 224.) There can be no doubt that some of these buried vessels are of far more ancient date than others. Those most roughly hewn, may be relics of the stone period; those more smoothly cut, of the bronze age; and the regularly built boat of Bankton may perhaps come within the age of iron. The occurrence of all of them in one and the same upraised marine formation by no means implies that they belong to the same era, for in the beds of all great rivers and estuaries, there are changes continually in progress brought about by the deposition, removal, and redeposition of gravel, sand, and fine sediment, and by the shifting of the channel of the main currents from year to year, and from century to century. All these it behoves the geologist and antiquary to bear in mind, so as to be always on their guard, when they are endeavouring to settle the relative date, whether of objects of art or of organic remains embedded in any set of alluvial strata. Some judicious observations on this head occur in Mr. Geikie's memoir above cited, which are so much in point that I shall give them in full, and in his own words. "The relative position in the silt, from which the canoes were exhumed, could help us little in any attempt to ascertain their relative ages, unless they had been found vertically above each other. The varying depths of an estuary, its banks of silt and sand, the set of its currents, and the influence of its tides in scouring out alluvium from some parts of its bottom and redepositing it in others, are circumstances which require to be taken into account in all such calculations. Mere coincidence of depth from the present surface of the ground, which is tolerably uniform in level, by no means necessarily proves contemporaneous deposition. Nor would such an inference follow even from the occurrence of the remains in distant parts of the very same stratum. A canoe might be capsized and sent to the bottom just beneath low-water mark; another might experience a similar fate on the following day, but in the middle of the channel. Both would become silted up on the floor of the estuary; but as that floor would be perhaps 20 feet deeper in the centre than towards the margin of the river, the one canoe might actually be twenty feet deeper in the alluvium than the other; and on the upheaval of the alluvial deposits, if we were to argue merely from the depth at which the remains were embedded, we should pronounce the canoe found at the one locality to be immensely older than the other, seeing that the fine mud of the estuary is deposited very slowly and that it must therefore have taken a long period to form so great a thickness as 20 feet. Again, the tides and currents of the estuary, by changing their direction, might sweep away a considerable mass of alluvium from the bottom, laying bare a canoe that may have foundered many centuries before. After the lapse of so long an interval, another vessel might go to the bottom in the same locality and be there covered up with the older one on the same general plane. These two vessels, found in such a position, would naturally be classed together as of the same age, and yet it is demonstrable that a very long period may have elapsed between the date of the one and that of the other. Such an association of these canoes, therefore, cannot be regarded as proving synchronous deposition; nor, on the other hand, can we affirm any difference of age from mere relative position, unless we see one canoe actually buried beneath another."* (* Geikie, "Quarterly Journal of the Geological Society" volume 18 1862, page 222.) At the time when the ancient vessels, above described, were navigating the waters where the city of Glasgow now stands, the whole of the low lands which bordered the present estuary of the Clyde formed the bed of a shallow sea. The emergence appears to have taken place gradually and by intermittent movements, for Mr. Buchanan describes several narrow terraces one above the other on the site of the city itself, with steep intervening slopes composed of the laminated estuary formation. Each terrace and steep slope probably mark pauses in the process of upheaval, during which low cliffs were formed, with beaches at their base. Five of the canoes were found within the precincts of the city at different heights on or near such terraces. As to the date of the upheaval, the greater part of it cannot be assigned to the stone period, but must have taken place after tools of metal had come into use. Until lately, when attempts were made to estimate the probable antiquity of such changes of level, it was confidently assumed, as a safe starting-point, that no alteration had occurred in the relative level of land and sea, in the central district of Scotland, since the construction of the Roman or Pictish wall (the "Wall of Antonine"), which reached from the Firth of Forth to that of the Clyde. The two extremities, it was said, of this ancient structure, bear such a relation to the present level of the two estuaries, that neither subsidence nor elevation of the land could have occurred for seventeen centuries at least. But Mr. Geikie has lately shown that a depression of 25 feet on the Forth would not lay the eastern extremity of the Roman wall at Carriden under water, and he was therefore desirous of knowing whether the western end of the same would be submerged by a similar amount of subsidence. It has always been acknowledged that the wall terminated upon an eminence called the Chapel Hill, near the village of West Kilpatrick, on the Clyde. The foot of this hill, Mr. Geikie estimates to be about 25 or 27 feet above high-water mark, so that a subsidence of 25 feet could not lay it under water. Antiquaries have sometimes wondered that the Romans did not carry the wall farther west than this Chapel Hill; but Mr. Geikie now suggests, in explanation, that all the low land at present intervening between that point and the mouth of the Clyde, was sixteen or seventeen centuries ago, washed by the tides at high water. The wall of Antonine, therefore, yields no evidence in favour of the land having remained stationary since the time of the Romans, but on the contrary, appears to indicate that since its erection the land has actually risen. Recent explorations by Mr. Geikie and Dr. Young, of the sites of the old Roman harbours along the southern margin of the Firth of Forth, lead to similar inferences. In the first place, it has long been known that there is a raised beach containing marine shells of living littoral species, at a height of about 25 feet, at Leith, as well as at other places along the coast above and below Edinburgh. Inveresk, a few miles below that city, is the site of an ancient Roman port, and if we suppose the sea at high water to have washed the foot of the heights on which the town stood, the tide would have ascended far up the valley of the Esk, and would have made the mouth of that river a safe and commodious harbour; whereas, had it been a shoaling estuary, as at present, it is difficult to see how the Romans should have made choice of it as a port. At Cramond, at the mouth of the river Almond, above Edinburgh, was Alaterva, the chief Roman harbour on the southern coast of the Forth, where numerous coins, urns, sculptured stones and the remnant of a harbour have been detected. The old Roman quays built along what must then have been the sea margin, have been found on what is now dry land, and although some silt carried down in suspension by the waters of the Forth may account for a part of the gain of low land, we yet require an upward movement of about 20 feet to explain the growth of the dreary expanse of mud now stretching along the shore and extending outwards, where it attains its greatest breadth, well-nigh two miles, across which vessels, even of light burden, can now only venture at full tide. Had these shoals existed eighteen centuries ago, they would have prevented the Romans from selecting this as their chief port; whereas, if the land were now to sink 20 feet, Cramond would unquestionably be the best natural harbour along the whole of the south side of the Forth.* (* Geikie, "Edinburgh New Philosophical Journal" for July 1861.) Corresponding in level with the raised beach at Leith, above mentioned (or about 25 feet above high-water mark), is the Carse of Stirling, a low tract of land consisting of loamy and peaty beds, in which several skeletons of whales of large size have been found. One of these was dug up at Airthrie,* near Stirling, about a mile from the river, and 7 miles from the sea. (* Bald, "Edinburgh Philosophical Journal" 1 page 393 and "Memoirs of the Wernerian Society" 3 page 327.) Mr. Bald mentions that near it were found two pieces of stag's horn, artificially cut, through one of which a hole, about an inch in diameter, had been perforated. Another whale, 85 feet long, was found at Dunmore, a few miles below Stirling,* which, like that of Airthrie, lay about 20 feet above high-water mark. (* "Edinburgh Philosophical Journal" 11 pages 220, 415.) Three other skeletons of whales were found at Blair Drummond, between the years 1819 and 1824, 7 miles up the estuary above Stirling,* also at an elevation of between 20 and 30 feet above the sea. Near two of these whales, pointed instruments of deer's horn were found, one of which retained part of a wooden handle, probably preserved by having been enclosed in peat. This weapon is now in the museum at Edinburgh. (* "Memoirs of the Wernerian Society" volume 5 page 440.) The position of these fossil whales and bone implements, and still more of an iron anchor found in the Carse of Falkirk, below Stirling, shows that the upheaval by which the raised beach of Leith was laid dry extended far westward probably as far as the Clyde, where, as we have seen, marine strata containing buried canoes rise to a similar height above the sea. The same upward movement which reached simultaneously east and west from sea to sea was also felt as far north as the estuary of the Tay. This may be inferred from the Celtic name of Inch being attached to many hillocks, which rise above the general level of the alluvial plains, implying that these eminences were once surrounded by water or marshy ground. At various localities also in the silt of the Carse of Gowrie iron implements have been found. The raised beach, also containing a great number of marine shells of recent species, traced up to a height of 14 feet above the sea by Mr. W.J. Hamilton at Elie, on the southern coast of Fife, is doubtless another effect of the same extensive upheaval.* (* "Proceedings of the Geological Society" volume 2 1833 page 280.) A similar movement would also account for some changes which antiquaries have recorded much farther south, on the borders of the Solway Firth; though in this case, as in that of the estuary of the Forth, the conversion of sea into land has always been referred to the silting up of estuaries, and not to upheaval. Thus Horsley insists on the difficulty of explaining the position of certain Roman stations, on the Solway, the Forth, and the Clyde, without assuming that the sea has been excluded from certain areas which it formerly occupied.* (* "Britannia" page 157 1860.) On a review of the whole evidence, geological and archaeological, afforded by the Scottish coast-line, we may conclude that the last upheaval of 25 feet took place not only since the first human population settled in the island; but long after metallic implements had come into use, and there seems even a strong presumption in favour of the opinion that the date of the elevation may have been subsequent to the Roman occupation. But the 25 feet rise is only the last stage of a long antecedent process of elevation, for examples of Recent marine shells have been observed 40 feet and upwards above the sea in Ayrshire. At one of these localities, Mr. Smith of Jordanhill informs me that a rude ornament made of cannel coal has been found on the coast in the parish of Dundonald, lying 50 feet above the sea-level, on the surface of the boulder-clay or till, and covered with gravel containing marine shells. If we suppose the upward movement to have been uniform in central Scotland before and after the Roman era, and assume that as 25 feet indicate seventeen centuries, so 50 feet imply a lapse of twice that number, or 3400 years, we should then carry back the date of the ornament in question to fifteen centuries before our era, or to the days of Pharaoh, and the period usually assigned to the exodus of the Israelites from Egypt. [8] But all such estimates must be considered, in the present state of science, as tentative and conjectural, since the rate of movement of the land may not have been uniform, and its direction not always upwards, and there may have been long stationary periods, one of which of more than usual duration seems indicated by the 50-foot raised beach, which has been traced for vast distances along the western coast of Scotland. COAST OF CORNWALL. Sir H. De la Beche has adduced several proofs of changes of level, in the course of the human period, in his "Report on the Geology of Cornwall and Devon," 1839. He mentions (page 406) that several human skulls and works of art, buried in an estuary deposit, were found in mining gravel for tin at Pentuan, near St. Austell, the skulls lying at the depth of 40 feet from the surface, and others at Carnon at the depth of 53 feet. The overlying strata were marine, containing sea-shells of living species, and bones of whales, besides the remains of several living species of mammalia. Other examples of works of art, such as stone hatchets, canoes, and ships, buried in ancient river-beds in England, and in peat and shell-marl, I have mentioned in my work before cited. SWEDEN AND NORWAY. In the same work I have shown that near Stockholm, in Sweden, there occur, at slight elevations above the sea-level, horizontal beds of sand, loam, and marl, containing the same peculiar assemblage of testacea which now live in the brackish waters of the Baltic. Mingled with these, at different depths, have been detected various works of art implying a rude state of civilization, and some vessels built before the introduction of iron, and even the remains of an ancient hut, the marine strata containing it, which had been formed during a previous depression, having been upraised, so that the upper beds are now 60 feet higher than the surface of the Baltic. In the neighbourhood of these recent strata, both to the north-west and south of Stockholm, other deposits similar in mineral composition occur, which ascend to greater heights, in which precisely the same assemblage of fossil shells is met with, but without any intermixture, so far as is yet known, of human bones or fabricated articles. On the opposite or western coast of Sweden, at Uddevalla, Post-Tertiary strata, containing recent shells, not of that brackish water character peculiar to the Baltic, but such as now live in the Northern Ocean, ascend to the height of 200 feet; and beds of clay and sand of the same age attain elevations of 300 and even 600 feet in Norway, where they have been usually described as "raised beaches." They are, however, thick deposits of submarine origin, spreading far and wide, and filling valleys in the granite and gneiss, just as the Tertiary formations, in different parts of Europe, cover or fill depressions in the older rocks. Although the fossil fauna characterising these upraised sands and clays consists exclusively of existing northern species of testacea, it is more than probable that they may not all belong to that division of the Pleistocene strata which we are now considering. If the contemporary mammalia were known, they would, in all likelihood, be found to be referable, at least in part, to extinct species; for, according to Loven (an able living naturalist of Norway), the species do not constitute such an assemblage as now inhabits corresponding latitudes in the North Sea. On the contrary, they decidedly represent a more arctic fauna. In order to find the same species flourishing in equal abundance, or in many cases to find them at all, we must go northwards to higher latitudes than Uddevalla in Sweden, or even nearer the pole than Central Norway. Judging by the uniformity of climate now prevailing from century to century, and the insensible rate of variation in the geographical distribution of organic beings in our own times, we may presume that an extremely lengthened period was required even for so slight a modification in the range of the molluscous fauna, as that of which the evidence is here brought to light. There are also other independent reasons for suspecting that the antiquity of these deposits may be indefinitely great as compared to the historical period. I allude to their present elevation above the sea, some of them rising, in Norway, to the height of 600 feet or more. The upward movement now in progress in parts of Norway and Sweden extends, as I have elsewhere shown,* throughout an area about 1000 miles north and south, and for an unknown distance east and west, the amount of elevation always increasing as we proceed towards the North Cape, where it is said to equal 5 feet in a century. (* "Principles" 9th edition chapter 30.) If we could assume that there had been an average of 2 1/2 feet in each hundred years for the last fifty centuries, this would give an elevation of 125 feet in that period. In other words, it would follow that the shores, and a considerable area of the former bed of the North Sea, had been uplifted vertically to that amount, and converted into land in the course of the last 5000 years. A mean rate of continuous vertical elevation of 2 1/2 feet in a century would, I conceive, be a high average; yet, even if this be assumed, it would require 24,000 years for parts of the sea-coast of Norway, where the Pleistocene marine strata occur, to attain the height of 600 feet. [9] CHAPTER 4. -- PLEISTOCENE PERIOD--BONES OF MAN AND EXTINCT MAMMALIA IN BELGIAN CAVERNS. Earliest Discoveries in Caves of Languedoc of Human Remains with Bones of extinct Mammalia. Researches in 1833 of Dr. Schmerling in the Liege Caverns. Scattered Portions of Human Skeletons associated with Bones of Elephant and Rhinoceros. Distribution and probable Mode of Introduction of the Bones. Implements of Flint and Bone. Schmerling's Conclusions as to the Antiquity of Man ignored. Present State of the Belgian Caves. Human Bones recently found in Cave of Engihoul. Engulfed Rivers. Stalagmitic Crust. Antiquity of the Human Remains in Belgium how proved. Having hitherto considered those formations in which both the fossil shells and the mammalia are of living species, we may now turn our attention to those of older date, in which the shells being all recent, some of the accompanying mammalia are extinct, or belong to species not known to have lived within the times of history or tradition. DISCOVERIES OF MM. TOURNAL AND CHRISTOL IN 1828 IN THE SOUTH OF FRANCE. In the "Principles of Geology," when treating of the fossil remains found in alluvium and the mud of caverns, I gave an account in 1832 of the investigations made by MM. Tournal and Christol in the South of France.* (* 1st edition volume 2 chapter 14 1832, and 9th edition page 738, 1853.) M. Tournal stated in his memoir that in the cavern of Bize, in the department of the Aude, he had found human bones and teeth, together with fragments of rude pottery, in the same mud and breccia cemented by stalagmite in which land-shells of living species were embedded, and the bones of mammalia, some of extinct, others of recent species. The human bones were declared by his fellow-labourer, M. Marcel de Serres, to be in the same chemical condition as those of the accompanying quadrupeds.* (* "Annales des Sciences Naturelles" tome 15 1828 page 348.) Speaking of these fossils of the Bize cavern five years later, M. Tournal observed that they could not be referred, as some suggested, to a "diluvial catastrophe," for they evidently had not been washed in suddenly by a transient flood, but must have been introduced gradually, together with the enveloping mud and pebbles, at successive periods.* (* "Annales de Chimie et de Physique" 1833 page 161.) M. Christol, who was engaged at the same time in similar researches in another part of Languedoc, published an account of them a year later, in which he described some human bones, as occurring in the cavern of Pondres, near Nimes, in the same mud with the bones of an extinct hyaena and rhinoceros.* (* Christol, "Notice sur les Ossements humains des Cavernes du Gard" Montpellier 1829.) The cavern was in this instance filled up to the roof with mud and gravel, in which fragments of two kinds of pottery were detected, the lowest and rudest near the bottom of the cave, below the level of the extinct mammalia. It has never been questioned that the hyaena and rhinoceros found by M. Christol were of extinct species; but whether the animals enumerated by M. Tournal might not all of them be referred to quadrupeds which are known to have been living in Europe in the historical period seems doubtful. They were said to consist of a stag, an antelope, and a goat, all named by M. Marcel de Serres as new; but the majority of palaeontologists do not agree with this opinion. Still it is true, as M. Lartet remarks, that the fauna of the cavern of Bize must be of very high antiquity, as shown by the presence, not only of the Lithuanian aurochs (Bison europaeus), but also of the reindeer, which has not been an inhabitant of the South of France in historical times, and which, in that country, is almost everywhere associated, whether in ancient alluvium or in the mud of caverns, with the mammoth. In my work before cited,* I stated that M. Desnoyers, an observer equally well versed in geology and archaeology, had disputed the conclusion arrived at by MM. Tournal and Christol, that the fossil rhinoceros, hyaena, bear, and other lost species had once been inhabitants of France contemporaneously with Man. (* "Principles" 9th edition page 739.) "The flint hatchets and arrow-heads," he said, "and the pointed bones and coarse pottery of many French and English caves, agree precisely in character with those found in the tumuli, and under the dolmens (rude altars of unhewn stone) of the primitive inhabitants of Gaul, Britain, and Germany. The human bones, therefore, in the caves which are associated with such fabricated objects, must belong not to antediluvian periods, but to a people in the same stage of civilization as those who constructed the tumuli and altars." "In the Gaulish monuments," he added, "we find, together with the objects of industry above mentioned, the bones of wild and domestic animals of species now inhabiting Europe, particularly of deer, sheep, wild boars, dogs, horses, and oxen. This fact has been ascertained in Quercy and other provinces; and it is supposed by antiquaries that the animals in question were placed beneath the Celtic altars in memory of sacrifices offered to the Gaulish divinity Hesus, and in the tombs to commemorate funeral repasts, and also from a superstition prevalent among savage nations, which induces them to lay up provisions for the manes of the dead in a future life. But in none of these ancient monuments have any bones been found of the elephant, rhinoceros, hyaena, tiger, and other quadrupeds, such as are found in caves, which might certainly have been expected had these species continued to flourish at the time that this part of Gaul was inhabited by Man."* (* Desnoyers, "Bulletin de la Societe Geologique de France" tome 2 page 252; and article on Caverns, "Dictionnaire Universelle d'Histoire Naturelle" Paris 1845.) After giving no small weight to the arguments of M. Desnoyers, and the writings of Dr. Buckland on the same subject, and myself visiting several caves in Germany, I came to the opinion that the human bones mixed with those of extinct animals, in osseous breccias and cavern mud, in different parts of Europe, were probably not coeval. The caverns having been at one period the dens of wild beasts, and having served at other times as places of human habitation, worship, sepulture, concealment, or defence, one might easily conceive that the bones of Man and those of animals, which were strewed over the floors of subterranean cavities, or which had fallen into tortuous rents connecting them with the surface, might, when swept away by floods, be mingled in one promiscuous heap in the same ossiferous mud or breccia.* (* "Principles" 9th edition page 740.) That such intermixtures have really taken place in some caverns, and that geologists have occasionally been deceived, and have assigned to one and the same period fossils which had really been introduced at successive times, will readily be conceded. But of late years we have obtained convincing proofs, as we shall see in the sequel, that the mammoth, and many other extinct mammalian species very common in caves, occur also in undisturbed alluvium, embedded in such a manner with works of art, as to leave no room for doubt that Man and the mammoth coexisted; Such discoveries have led me, and other geologists, to reconsider the evidence previously derived from caves brought forward in proof of the high antiquity of Man. With a view of re-examining this evidence, I have lately explored several caverns in Belgium and other countries, and re-read the principal memoirs and treatises treating of the fossil remains preserved in them, the results of which inquiries I shall now proceed to lay before the reader. RESEARCHES, IN 1833-1834, OF DR. SCHMERLING IN THE CAVERNS NEAR LIEGE. The late Dr. Schmerling of Liege, a skilful anatomist and palaeontologist, after devoting several years to the exploring of the numerous ossiferous caverns which border the valleys of the Meuse and its tributaries, published two volumes descriptive of the contents of more than forty caverns. One of these volumes consisted of an atlas of plates, illustrative of the fossil bones.* (* "Recherches sur les Ossements fossiles decouverts dans les Cavernes de la Province de Liege", Liege 1833-1834.) Many of the caverns had never before been entered by scientific observers, and their floors were encrusted with unbroken stalagmite. At a very early stage of his investigations, Dr. Schmerling found the bones of Man so rolled and scattered as to preclude all idea of their having been intentionally buried on the spot. He also remarked that they were of the same colour, and in the same condition as to the amount of animal matter contained in them, as those of the accompanying animals, some of which, like the cave-bear, hyaena, elephant, and rhinoceros, were extinct; others, like the wild cat, beaver, wild boar, roe-deer, wolf, and hedgehog, still extant. The fossils were lighter than fresh bones, except such as had their pores filled with carbonate of lime, in which case they were often much heavier. The human remains of most frequent occurrence were teeth detached from the jaw, and the carpal, metacarpal, tarsal, metatarsal, and phalangeal bones separated from the rest of the skeleton. The corresponding bones of the cave-bear, the most abundant of the accompanying mammalia, were also found in the Liege caverns more commonly than any others, and in the same scattered condition. Occasionally, some of the long bones of mammalia were observed to have been first broken across, and then reunited or cemented again by stalagmite, as they lay on the floor of the cave. No gnawed bones nor any coprolites were found by Schmerling. He therefore inferred that the caverns of the province of Liege had not been the dens of wild beasts, but that their organic and inorganic contents had been swept into them by streams communicating with the surface of the country. The bones, he suggested, may often have been rolled in the beds of such streams before they reached their underground destination. To the same agency the introduction of many land-shells dispersed through the cave-mud was ascribed, such as Helix nemoralis, H. lapicida, H. pomatia, and others of living species. Mingled with such shells, in some rare instances, the bones of freshwater fish, and of a snake (Coluber), as well as of several birds, were detected. The occurrence here and there of bones in a very perfect state, or of several bones belonging to the same skeleton in natural juxtaposition, and having all their most delicate apophyses uninjured, while many accompanying bones in the same breccia were rolled, broken, or decayed, was accounted for by supposing that portions of carcasses were sometimes floated in during floods while still clothed with their flesh. No example was discovered of an entire skeleton, not even of one of the smaller mammalia, the bones of which are usually the least injured. The incompleteness of each skeleton was especially ascertained in regard to the human subjects, Dr. Schmerling being careful, whenever a fragment of such presented itself, to explore the cavern himself, and see whether any other bones of the same skeleton could be found. In the Engis cavern, distant about eight miles to the south-west of Liege, on the left bank of the Meuse, the remains of at least three human individuals were disinterred. The skull of one of these, that of a young person, was embedded by the side of a mammoth's tooth. It was entire but so fragile, that nearly all of it fell to pieces during its extraction. Another skull, that of an adult individual, and the only one preserved by Dr. Schmerling in a sufficient state of integrity to enable the anatomist to speculate on the race to which it belonged, was buried 5 feet deep in a breccia, in which the tooth of a rhinoceros, several bones of a horse, and some of the reindeer, together with some ruminants, occurred. This skull, now in the museum of the University of Liege, is figured in Chapter 5 (Figure 2), where further observations will be offered on its anatomical character, after a fuller account of the contents of the Liege caverns has been laid before the reader. On the right bank of the Meuse, on the opposite side of the river to Engis, is the cavern of Engihoul. Bones of extinct animals mingled with those of Man were observed to abound in both caverns; but with this difference, that whereas in the Engis cave there were several human crania and very few other bones, in Engihoul there occurred numerous bones of the extremities belonging to at least three human individuals, and only two small fragments of a cranium. The like capricious distribution held good in other caverns, especially with reference to the cave-bear, the most frequent of the extinct mammalia. Thus, for example in the cave of Chokier, skulls of the bear were few, and other parts of the skeleton abundant, whereas in several other caverns these proportions were exactly reversed, while at Goffontaine skulls of the bear and other parts of the skeleton were found in their natural numerical proportions. Speaking generally, it may be said that human bones, where any were met with, occurred at all depths in the cave-mud and gravel, sometimes above and sometimes below those of the bear, elephant, rhinoceros, hyaena, etc. Some rude flint implements of the kind commonly called flint knives or flakes, of a triangular form in the cross section (as in Figure 14), were found by Schmerling dispersed generally through the cave-mud, but he was too much engrossed with his osteological inquiries to collect them diligently. He preserved some few of them, however, which I have seen in the museum at Liege. He also discovered in the cave of Chokier, 2 1/2 miles south-west from Liege, a polished and jointed needle-shaped bone, with a hole pierced obliquely through it at the base; such a cavity, he observed, as had never given passage to an artery. This instrument was embedded in the same matrix with the remains of a rhinoceros.* (* Schmerling part 2 page 177.) Another cut bone and several artificially-shaped flints were found in the Engis cave, near the human skulls before alluded to. Schmerling observed, and we shall have to refer to the fact in the sequel (Chapter 8), that although in some forty fossiliferous caves explored by him human bones were the exception, yet these flint implements were universal, and he added that "none of them could have been subsequently introduced, being precisely in the same position as the remains of the accompanying animals." "I therefore," he continues, "attach great importance to their presence; for even if I had not found the human bones under conditions entirely favourable to their being considered as belonging to the antediluvian epoch, proofs of Man's existence would still have been supplied by the cut bones and worked flints."* (* Schmerling, part 2 page 179.) Dr. Schmerling, therefore, had no hesitation in concluding from the various facts ascertained by him, that Man once lived in the Liege district contemporaneously with the cave-bear and several other extinct species of quadrupeds. But he was much at a loss when he attempted to invent a theory to explain the former state of the fauna of the region now drained by the Meuse; for he shared the notion, then very prevalent among naturalists, that the mammoth and the hyaena* were beasts of a warmer climate than that now proper to Western Europe. (* Ibid. part 2 pages 70 and 96.) In order to account for the presence of such "tropical species," he was half-inclined to imagine that they had been transported by a flood from some distant region; then again he raised the question whether they might not have been washed out of an older alluvium, which may have pre-existed in the neighbourhood. This last hypothesis was directly at variance with his own statements, that the remains of the mammoth and hyaena were identical in appearance, colour, and chemical condition with those of the bear and other associated fossil animals, none of which exhibited signs of having been previously enveloped in any dissimilar matrix. Another enigma which led Schmerling astray in some of his geological speculations was the supposed presence of the agouti, a South American rodent, "proper to the torrid zone." My friend M. Lartet, guided by Schmerling's figures of the teeth of this species, suggests, and I have little doubt with good reason, that they appertain to the porcupine, a genus found fossil in Pleistocene deposits of certain caverns in the south of France. In the year 1833, I passed through Liege, on my way to the Rhine, and conversed with Dr. Schmerling, who showed me his splendid collection, and when I expressed some incredulity respecting the alleged antiquity of the fossil human bones, he pointedly remarked that if I doubted their having been contemporaneous with the bear or rhinoceros, on the ground of Man being a species of more modern date, I ought equally to doubt the co-existence of all the other living species, such as the red deer, roe, wild cat, wild boar, wolf, fox, weasel, beaver, hare, rabbit, hedgehog, mole, dormouse, field-mouse, water-rat, shrew, and others, the bones of which he had found scattered everywhere indiscriminately through the same mud with the extinct quadrupeds. The year after this conversation I cited Schmerling's opinions, and the facts bearing on the antiquity of Man, in the 3rd edition of my "Principles of Geology" (page 161, 1834), and in succeeding editions, without pretending to call in question their trustworthiness, but at the same time without giving them the weight which I now consider they were entitled to. He had accumulated ample evidence to prove that Man had been introduced into the earth at an earlier period than geologists were then willing to believe. One positive fact, it will be said, attested by so competent a witness, ought to have outweighed any amount of negative testimony, previously accumulated, respecting the non-occurrence elsewhere of human remains in formations of the like antiquity. In reply, I can only plead that a discovery which seems to contradict the general tenor of previous investigations is naturally received with much hesitation. To have undertaken in 1832, with a view of testing its truth, to follow the Belgian philosopher through every stage of his observations and proofs, would have been no easy task even for one well-skilled in geology and osteology. To be let down, as Schmerling was, day after day, by a rope tied to a tree, so as to slide to the foot of the first opening of the Engis cave,* where the best-preserved human skulls were found; and, after thus gaining access to the first subterranean gallery, to creep on all fours through a contracted passage leading to larger chambers, there to superintend by torchlight, week after week and year after year, the workmen who were breaking through the stalagmitic crust as hard as marble, in order to remove piece by piece the underlying bone-breccia nearly as hard; to stand for hours with one's feet in the mud, and with water dripping from the roof on one's head, in order to mark the position and guard against the loss of each single bone of a skeleton; and at length, after finding leisure, strength, and courage for all these operations, to look forward, as the fruits of one's labour, to the publication of unwelcome intelligence, opposed to the prepossessions of the scientific as well as of the unscientific public--when these circumstances are taken into account, we need scarcely wonder, not only that a passing traveller failed to stop and scrutinise the evidence, but that a quarter of a century should have elapsed before even the neighbouring professors of the University of Liege came forth to vindicate the truthfulness of their indefatigable and clear-sighted countryman. (* Schmerling part 1 page 30.) In 1860, when I revisited Liege, twenty-six years after my interview with Schmerling, I found that several of the caverns described by him had in the interval been annihilated. Not a vestige, for example, of the caves of Engis, Chokier, and Goffontaine remained. The calcareous stone, in the heart of which the cavities once existed, had been quarried away, and removed bodily for building and lime-making. Fortunately, a great part of the Engihoul cavern, situated on the right bank of the Meuse, was still in the same state as when Schmerling delved into it in 1831, and drew from it the bones of three human skeletons. I determined, therefore, to examine it, and was so fortunate as to obtain the assistance of a zealous naturalist of Liege, Professor Malaise, who accompanied me to the cavern, where we engaged some workmen to break through the crust of stalagmite, so that we could search for bones in the undisturbed earth beneath. Bones and teeth of the cave-bear were soon found, and several other extinct quadrupeds which Schmerling has enumerated. My companion, continuing the work perseveringly for weeks after my departure, succeeded at length in extracting from the same deposit, at the depth of 2 feet below the crust of stalagmite, three fragments of a human skull, and two perfect lower jaws with teeth, all associated in such a manner with the bones of bears, large pachyderms, and ruminants, and so precisely resembling these in colour and state of preservation, as to leave no doubt in his mind that Man was contemporary with the extinct animals. Professor Malaise has given figures of the human remains in the "Bulletin" of the Royal Academy of Belgium for 1860.* (* Volume 10 page 546.) The rock in which the Liege caverns occur belongs generally to the Carboniferous or Mountain Limestone, in some few cases only to the older Devonian formation. Whenever the work of destruction has not gone too far, magnificent sections, sometimes 200 and 300 feet in height, are exposed to view. They confirm Schmerling's doctrine, that most of the materials, organic and inorganic, now filling the caverns, have been washed into them through narrow vertical or oblique fissures, the upper extremities of which are choked up with soil and gravel, and would scarcely ever be discoverable at the surface, especially in so wooded a country. Among the sections obtained by quarrying, one of the finest which I saw was in the beautiful valley of Fond du Foret, above Chaudefontaine, not far from the village of Magnee, where one of the rents communicating with the surface has been filled up to the brim with rounded and half-rounded stones, angular pieces of limestone and shale, besides sand and mud, together with bones, chiefly of the cave-bear. Connected with this main duct, which is from 1 to 2 feet in width, are several minor ones, each from 1 to 3 inches wide, also extending to the upper country or table-land, and choked up with similar materials. They are inclined at angles of 30 and 40 degrees, their walls being generally coated with stalactite, pieces of which have here and there been broken off and mingled with the contents of the rents, thus helping to explain why we so often meet with detached pieces of that substance in the mud and breccia of the Belgian caves. It is not easy to conceive that a solid horizontal floor of hard stalagmite should, after its formation, be broken up by running water; but when the walls of steep and tortuous rents, serving as feeders to the principal fissures and to inferior vaults and galleries are encrusted with stalagmite, some of the incrustation may readily be torn up when heavy fragments of rock are hurried by a flood through passages inclined at angles of 30 or 40 degrees. The decay and decomposition of the fossil bones seem to have been arrested in most of the caves by a constant supply of water charged with carbonate of lime, which dripped from the roofs while the caves were becoming gradually filled up. By similar agency the mud, sand, and pebbles were usually consolidated. The following explanation of this phenomenon has been suggested by the eminent chemist Liebig. On the surface of Franconia, where the limestone abounds in caverns, is a fertile soil in which vegetable matter is continually decaying. This mould or humus, being acted on by moisture and air, evolves carbonic acid, which is dissolved by rain. The rain water, thus impregnated, permeates the porous limestone, dissolves a portion of it, and afterwards, when the excess of carbonic acid evaporates in the caverns, parts with the calcareous matter and forms stalactite. So long as water flows, even occasionally, through a suite of caverns, no layer of pure stalagmite can be produced; hence the formation of such a layer is generally an event posterior in date to the cessation of the old system of drainage, an event which might be brought about by an earthquake causing new fissures, or by the river wearing its way down to a lower level, and thenceforth running in a new channel. In all the subterranean cavities, more than forty in number, explored by Schmerling, he only observed one cave, namely that of Chokier, where there were two regular layers of stalagmite, divided by fossiliferous cave-mud. In this instance, we may suppose that the stream, after flowing for a long period at one level, cut its way down to an inferior suite of caverns, and, flowing through them for centuries, choked them up with debris; after which it rose once more to its original higher level: just as in the Mountain Limestone district of Yorkshire some rivers, habitually absorbed by a "swallow hole," are occasionally unable to discharge all their water through it; in which case they rise and rush through a higher subterranean passage, which was at some former period in the regular line of drainage, as is often attested by the fluviatile gravel still contained in it. There are now in the basin of the Meuse, not far from Liege, several examples of engulfed brooks and rivers: some of them, like that of St. Hadelin, east of Chaudefontaine, which reappears after an underground course of a mile or two; others, like the Vesdre, which is lost near Goffontaine, and after a time re-emerges; some, again, like the torrent near Magnee, which, after entering a cave, never again comes to the day. In the season of floods such streams are turbid at their entrance, but clear as a mountain-spring where they issue again; so that they must be slowly filling up cavities in the interior with mud, sand, pebbles, snail-shells, and the bones of animals which may be carried away during floods. The manner in which some of the large thigh and shank bones of the rhinoceros and other pachyderms are rounded, while some of the smaller bones of the same creatures, and of the hyaena, bear, and horse, are reduced to pebbles, shows that they were often transported for some distance in the channels of torrents, before they found a resting-place. When we desire to reason or speculate on the probable antiquity of human bones found fossil in such situations as the caverns near Liege, there are two classes of evidence to which we may appeal for our guidance. First, considerations of the time required to allow of many species of carnivorous and herbivorous animals, which flourished in the cave period, becoming first scarce, and then so entirely extinct as we have seen that they had become before the era of the Danish peat and Swiss lake dwellings; secondly, the great number of centuries necessary for the conversion of the physical geography of the Liege district from its ancient to its present configuration; so many old underground channels, through which brooks and rivers flowed in the cave period, being now laid dry and choked up. The great alterations which have taken place in the shape of the valley of the Meuse and some of its tributaries are often demonstrated by the abrupt manner in which the mouths of fossiliferous caverns open in the face of perpendicular precipices 200 feet or more in height above the present streams. There appears also, in many cases, to be such a correspondence in the openings of caverns on opposite sides of some of the valleys, both large and small, as to incline one to suspect that they originally belonged to a series of tunnels and galleries which were continuous before the present system of drainage came into play, or before the existing valleys were scooped out. Other signs of subsequent fluctuations are afforded by gravel containing elephant's bones at slight elevations above the Meuse and several of its tributaries. It may be objected that, according to the present rate of change, no lapse of ages would suffice to bring about such revolutions in physical geography as we are here contemplating. This may be true. It is more than probable that the rate of change was once far more active than it is now in the basin of the Meuse. Some of the nearest volcanoes, namely, those of the Lower Eifel about 60 miles to the eastward, seem to have been in eruption in Pleistocene times, and may perhaps have been connected and coeval with repeated risings or sinkings of the land in the Liege district. It might be said, with equal truth, that according to the present course of events, no series of ages would suffice to reproduce such an assemblage of cones and craters as those of the Eifel (near Andernach, for example); and yet some of them may be of sufficiently modern date to belong to the era when Man was contemporary with the mammoth and rhinoceros in the basin of the Meuse. But, although we may be unable to estimate the minimum of time required for the changes in physical geography above alluded to, we cannot fail to perceive that the duration of the period must have been very protracted, and that other ages of comparative inaction may have followed, separating the Pleistocene from the historical periods, and constituting an interval no less indefinite in its duration. CHAPTER 5. -- PLEISTOCENE PERIOD--FOSSIL HUMAN SKULLS OF THE NEANDERTHAL AND ENGIS CAVES. Human Skeleton found in Cave near Dusseldorf. Its geological Position and probable Age. Its abnormal and ape-like Characters. Fossil Human Skull of the Engis Cave near Liege. Professor Huxley's Description of these Skulls. Comparison of each, with extreme Varieties of the native Australian Race. Range of Capacity in the Human and Simian Brains. Skull from Borreby in Denmark. Conclusions of Professor Huxley. Bearing of the peculiar Characters of the Neanderthal Skull on the Hypothesis of Transmutation. FOSSIL HUMAN SKELETON OF THE NEANDERTHAL CAVE NEAR DUSSELDORF. Before I speak more particularly of the opinions which anatomists have expressed respecting the osteological characters of the human skull from Engis, near Liege, mentioned in the last chapter and described by Dr. Schmerling, it will be desirable to say something of the geological position of another skull, or rather skeleton, which, on account of its peculiar conformation, has excited no small sensation in the last few years. I allude to the skull found in 1857 in a cave situated in that part of the valley of the Dussel, near Dusseldorf, which is called the Neanderthal. The spot is a deep and narrow ravine about 70 English miles north-east of the region of the Liege caverns treated of in the last chapter, and close to the village and railway station of Hochdal between Dusseldorf and Elberfeld. The cave occurs in the precipitous southern or left side of the winding ravine, about sixty feet above the stream, and a hundred feet below the top of the cliff. The accompanying section (Figure 1.) will give the reader an idea of its position. [Illustration: Figure 1] When Dr. Fuhlrott of Elberfeld first examined the cave, he found it to be high enough to allow a man to enter. The width was 7 or 8 feet, and the length or depth 15. I visited the spot in 1860, in company with Dr. Fuhlrott, who had the kindness to come expressly from Elberfeld to be my guide, and who brought with him the original fossil skull, and a cast of the same, which he presented to me. In the interval of three years, between 1857 and 1860, the ledge of rock, f, on which the cave opened, and which was originally 20 feet wide, had been almost entirely quarried away, and, at the rate at which the work of dilapidation was proceeding, its complete destruction seemed near at hand. (FIGURE 1. SECTION OF THE NEANDERTHAL CAVE NEAR DUSSELDORF. a. Cavern 60 feet above the Dussel, and 100 feet below the surface of the country at c. b. Loam covering the floor of the cave near the bottom of which the human skeleton was found. b, c. Rent connecting the cave with the upper surface of the country. d. Superficial sandy loam. e. Devonian limestone. f. Terrace, or ledge of rock.) In the limestone are many fissures, one of which, still partially filled with mud and stones, is represented in the section at a c as continuous from the cave to the upper surface of the country. Through this passage the loam, and possibly the human body to which the bones belonged, may have been washed into the cave below. The loam, which covered the uneven bottom of the cave, was sparingly mixed with rounded fragments of chert, and was very similar in composition to that covering the general surface of that region. There was no crust of stalagmite overlying the mud in which the human skeleton was found, and no bones of other animals in the mud with the skeleton; but just before our visit in 1860 the tusk of a bear had been met with in some mud in a lateral embranchment of the cave, in a situation precisely similar to b, Figure 1, and on a level corresponding with that of the human skeleton. This tusk, shown us by the proprietor of the cave, was 2 1/2 inches long and quite perfect; but whether it was referable to a recent or extinct species of bear, I could not determine. From a printed letter of Dr. Fuhlrott we learn that on removing the loam, which was five feet thick, from the cave, the human skull was first noticed near the entrance, and, further in, the other bones lying in the same horizontal plane. It is supposed that the skeleton was complete, but the workmen, ignorant of its value, scattered and lost most of the bones, preserving only the larger ones.* (* Fuhlrott, Letter to Professor Schaaffhausen, cited "Natural History Review" Number 2 page 156. See also "Naturhistorischer Verein" Bonn 1859.) The cranium, which Dr. Fuhlrott showed me, was covered both on its outer and inner surface, and especially on the latter, with a profusion of dendritical crystallisations, and some other bones of the skeleton were ornamented in the same way. These markings, as Dr. Hermann von Meyer observes, afford no sure criterion of antiquity, for they have been observed on Roman bones. Nevertheless, they are more common in bones that have been long embedded in the earth. The skull and bones, moreover, of the Neanderthal skeleton had lost so much of their animal matter as to adhere strongly to the tongue, agreeing in this respect with the ordinary condition of fossil remains of the Pleistocene period. On the whole, I think it probable that this fossil may be of about the same age as those found by Schmerling in the Liege caverns; but, as no other animal remains were found with it, there is no proof that it may not be newer. Its position lends no countenance whatever to the supposition of its being more ancient. When the skull and other parts of the skeleton were first exhibited at a German scientific meeting at Bonn, in 1857, some doubts were expressed by several naturalists, whether it was truly human. Professor Schaaffhausen, who, with the other experienced zoologists, did not share these doubts, observed that the cranium, which included the frontal bone, both parietals, part of the squamous, and the upper third of the occipital, was of unusual size and thickness, the forehead narrow and very low, and the projection of the supra-orbital ridges enormously great. He also stated that the absolute and relative length of the thigh bone, humerus, radius, and ulna, agreed well with the dimensions of a European individual of like stature at the present day; but that the thickness of the bones was very extraordinary, and the elevations and depressions for the attachment of muscles were developed in an unusual degree. Some of the ribs, also, were of a singularly rounded shape and abrupt curvature, which was supposed to indicate great power in the thoracic muscles.* (* Professor Schaaffhausen's "Memoir" translated "Natural History Review" April 1861.) In the same memoir, the Prussian anatomist remarks that the depression of the forehead (See Figure 3.), is not due to any artificial flattening, such as is practised in various modes by barbarous nations in the Old and New World, the skull being quite symmetrical, and showing no indication of counter-pressure at the occiput; whereas, according to Morton, in the Flat-heads of the Columbia, the frontal and parietal bones are always unsymmetrical.* (* "Natural History Review" Number 2 page 160.) On the whole, Professor Schaaffhausen concluded that the individual to whom the Neanderthal skull belonged must have been distinguished by small cerebral development, and uncommon strength of corporeal frame. When on my return to England I showed the cast of the cranium to Professor Huxley, he remarked at once that it was the most ape-like skull he had ever beheld. Mr. Busk, after giving a translation of Professor Schaaffhausen's memoir in the "Natural History Review," added some valuable comments of his own on the characters in which this skull approached that of the gorilla and chimpanzee. Professor Huxley afterwards studied the cast with the object of assisting me to give illustrations of it in this work, and in doing so discovered what had not previously been observed, that it was quite as abnormal in the shape of its occipital as in that of its frontal or superciliary region. Before citing his words on the subject, I will offer a few remarks on the Engis skull which the same anatomist has compared with that of the Neanderthal. [10] FOSSIL SKULL OF THE ENGIS CAVE NEAR LIEGE. Among six or seven human skeletons, portions of which were collected by Dr. Schmerling from three or four caverns near Liege, embedded in the same matrix with the remains of the elephant, rhinoceros, bear, hyaena, and other extinct quadrupeds, the most perfect skull, as I have before stated, was that of an adult individual found in the cavern of Engis. This skull, Dr. Schmerling figured in his work, observing that it was too imperfect to enable the anatomist to determine the facial angle, but that one might infer, from the narrowness of the frontal portion, that it belonged to an individual of small intellectual development. He speculated on its Ethiopian affinities, but not confidently, observing truly that it would require many more specimens to enable an anatomist to arrive at sound conclusions on such a point. M. Geoffroy St. Hilaire and other osteologists, who examined the specimen, denied that it resembled a negro's skull. When I saw the original in the museum at Liege, I invited Dr. Spring, one of the professors of the university, to whom we are indebted for a valuable memoir on the human bones found in the cavern of Chauvaux, near Namur, to have a cast made of this Engis skull. He not only had the kindness to comply with my request, but rendered a service to the scientific world by adding to the original cranium several detached fragments which Dr. Schmerling had obtained from Engis, and which were found to fit in exactly, so that the cast represented at Figure 2 is more complete than that given in the first plate of Schmerling's work. It exhibits on the right side the position of the auditory foramen (see Figure 6), which was not included in Schmerling's figure. Mr. Busk, when he saw this cast, remarked to me that, although the forehead was, as Schmerling had truly stated, somewhat narrow, it might nevertheless be matched by the skulls of individuals of European race, an observation since fully borne out by measurements, as will be seen in the sequel. OBSERVATIONS BY PROFESSOR HUXLEY ON THE HUMAN SKULLS OF ENGIS AND THE NEANDERTHAL. [Illustration: Figure 2] "The Engis skull, as originally figured by Professor Schmerling, was in a very imperfect state; but other fragments have since been added to it by the care of Dr. Spring, and the cast upon which my observations are based (Figure 2) exhibits the frontal, parietal, and occipital regions, as far as the middle of the occipital foramen, with the squamous and mastoid portions of the right temporal bone entire, or nearly so, while the left temporal bone is wanting. From the middle of the occipital foramen to the middle of the roof of each orbit, the base of the skull is destroyed, and the facial bones are entirely absent. "The extreme length of the skull is 7.7 inches, and as its extreme breadth is not more than 5.25, its form is decidedly dolichocephalic. At the same time its height (4 3/4 inches from the plane of the glabello-occipital line (a d) to the vertex) is good, and the forehead is well arched; so that while the horizontal circumference of the skull is about 20 1/2 inches, the longitudinal arc from the nasal spine of the frontal bone to the occipital protuberance (d) measures about 13 3/4 inches. The transverse arc from one auditory foramen to the other across the middle of the sagittal suture measures about 13 inches. The sagittal suture (b c) is 5 1/2 inches in length. The superciliary prominences are well, but not excessively, developed, and are separated by a median depression in the region of the glabella. They indicate large frontal sinuses. If a line joining the glabella and the occipital protuberance (a d) be made horizontal, no part of the occiput projects more than 1/10th of an inch behind the posterior extremity of that line; and the upper edge of the auditory foramen is almost in contact with the same line, or rather with one drawn parallel to it on the outer surface of the skull. (FIGURE 2. SIDE VIEW OF THE CAST OF PART OF A HUMAN SKULL FOUND BY DR. SCHMERLING EMBEDDED AMONGST THE REMAINS OF EXTINCT MAMMALIA IN THE CAVE OF ENGIS, NEAR LIEGE. a. Superciliary ridge and glabella. b. Coronal suture. c. The apex of the lamboidal suture. d. The occipital protuberance.) "The Neanderthal skull, with which also I am acquainted only by means of Professor Schaaffhausen's drawings of an excellent cast and of photographs, is so extremely different in appearance from the Engis cranium, that it might well be supposed to belong to a distinct race of mankind. It is 8 inches in extreme length and 5.75 inches in extreme breadth, but only measures 3.4 inches from the glabello-occipital line to the vertex. The longitudinal arc, measured as above, is 12 inches; the transverse arc cannot be exactly ascertained, in consequence of the absence of the temporal bones, but was probably about the same, and certainly exceeded 10 1/4 inches. The horizontal circumference is 23 inches. This great circumference arises largely from the vast development of the superciliary ridges, which are occupied by great frontal sinuses whose inferior apertures are displayed exceedingly well in one of Dr. Fuhlrott's photographs, and form a continuous transverse prominence, somewhat excavated in the middle line, across the lower part of the brows. In consequence of this structure, the forehead appears still lower and more retreating than it really is. To an anatomical eye the posterior part of the skull is even more striking than the anterior. The occipital protuberance occupies the extreme posterior end of the skull when the glabello-occipital line is made horizontal, and so far from any part of the occipital region extending beyond it, this region of the skull slopes obliquely upward and forward, so that the lambdoidal suture is situated well upon the upper surface of the cranium. At the same time, notwithstanding the great length of the skull, the sagittal suture is remarkably short (4 1/2 inches), and the squamosal suture is very straight. [Illustration: Figure 3. Cast of Human Skull] (FIGURE 3. SIDE VIEW OF THE CAST OF A PART OF A HUMAN SKULL FROM A CAVE IN THE NEANDERTHAL, NEAR DUSSELDORF. a. Superciliary ridge and glabella. b. The coronal suture. c. The apex of the lamboidal suture. d. The occipital protuberance.) "In human skulls, the superior curved ridge of the occipital bone and the occipital protuberance correspond, approximatively, with the level of the tentorium and with the lateral sinuses, and consequently with the inferior limit of the posterior lobes of the brain. At first, I found some difficulty in believing that a human brain could have its posterior lobes so flattened and diminished as must have been the case in the Neanderthal man, supposing the ordinary relation to obtain between the superior occipital ridges and the tentorium; but on my application, through Sir Charles Lyell, Dr. Fuhlrott, the possessor of the skull, was good enough not only to ascertain the existence of the lateral sinuses in their ordinary position, but to send convincing proofs of the fact, in excellent photographic views of the interior of the skull, exhibiting clear indications of these sinuses. "There can be no doubt that, as Professor Schaaffhausen and Mr. Busk have stated, this skull is the most brutal of all known human skulls, resembling those of the apes not only in the prodigious development of the superciliary prominences and the forward extension of the orbits, but still more in the depressed form of the brain-case, in the straightness of the squamosal suture, and in the complete retreat of the occiput forwards and upward, from the superior occipital ridges. [Illustration: Figure 4. Skull of Chimpanzee] (FIGURE 4. OUTLINE OF THE SKULL OF AN ADULT CHIMPANZEE, OF THAT FROM THE NEANDERTHAL, AND OF THAT OF A EUROPEAN, DRAWN TO THE SAME ABSOLUTE SIZE, IN ORDER BETTER TO EXHIBIT THEIR RELATIVE DIFFERENCES. The superciliary region of the Neanderthal skull appears less prominent than in Figure 3, as the contours are all taken along the middle line where the superciliary projection of the Neanderthal skull is least marked. a. The glabella. b. The occipital protuberance, or the point on the exterior of each skull which corresponds roughly with the attachment of the tentorium, or with the inferior boundary of the posterior cerebral lobes.) "But the cranium, in its present condition, is stated by Professor Schaaffhausen to contain 1033.24 cubic centimetres of water, or, in other words, about 63 English cubic inches. As the entire skull could hardly have held less than 12 cubic inches more, its minimum capacity may be estimated at 75 cubic inches. The most capacious healthy European skull yet measured had a capacity of 114 cubic inches, the smallest (as estimated by weight of brain) about 55 cubic inches, while, according to Professor Schaaffhausen, some Hindoo skulls have as small a capacity as about 46 cubic inches (27 ounces of water). The largest cranium of any Gorilla yet measured contained 34.5 cubic inches. The Neanderthal cranium stands, therefore, in capacity, very nearly on a level with the mean of the two human extremes, and very far above the pithecoid maximum. [Illustration: Figure 5. Skull] (FIGURE 5. SKULL ASSOCIATED WITH GROUND FLINT IMPLEMENTS, FROM A TUMULUS AT BORREBY IN DENMARK, AFTER A CAMERA LUCIDA DRAWING BY MR. G. BUSK, F.R.S. The thick dark line indicates so much of the skull as corresponds with the fragment from the Neanderthal. a. Superciliary ridge. b. Coronal suture. c. The apex of the lamboidal suture. d. The occipital protuberance. e. The auditory foramen.) "Hence, even in the absence of the bones of the arm and thigh, which, according to Professor Schaaffhausen, had the precise proportions found in Man, although they were stouter than ordinary human bones, there could be no reason for ascribing this cranium to anything but a man; while the strength and development of the muscular ridges of the limb-bones are characters in perfect accordance with those exhibited, in a minor degree, by the bones of such hardy savages, exposed to a rigorous climate, as the Patagonians. "The Neanderthal cranium has certainly not undergone compression, and, in reply to the suggestion that the skull is that of an idiot, it may be urged that the onus probandi lies with those who adopt the hypothesis. Idiotcy is compatible with very various forms and capacities of the cranium, but I know of none which present the least resemblance to the Neanderthal skull; and, furthermore, I shall proceed to show that the latter manifests but an extreme degree of a stage of degradation exhibited, as a natural condition, by the crania of certain races of mankind. "Mr. Busk drew my attention, some time ago, to the resemblance between some of the skulls taken from tumuli of the stone period at Borreby in Denmark, of which Mr. Busk possesses numerous accurate figures, and the Neanderthal cranium. One of the Borreby skulls in particular (Figure 5) has remarkably projecting superciliary ridges, a retreating forehead, a low flattened vertex, and an occiput which shelves upward and forward. But the skull is relatively higher and broader, or more brachycephalic, the sagittal suture longer, and the superciliary ridges less projecting, than in the Neanderthal skull. Nevertheless, there is, without doubt, much resemblance in character between the two skulls--a circumstance which is the more interesting, since the other Borreby skulls have better foreheads and less prominent superciliary ridges, and exhibit altogether a higher conformation. "The Borreby skulls belong to the stone period of Denmark, and the people to whom they appertained were probably either contemporaneous with, or later than, the makers of the 'refuse-heaps' of that country. In other words, they were subsequent to the last great physical changes of Europe, and were contemporaries of the urus and bison, not of the Elephas primigenius, Rhinoceros tichorhinus, and Hyaena spelaea. "Supposing for a moment, what is not proven, that the Neanderthal skull belonged to a race allied to the Borreby people and was as modern as they, it would be separated by as great a distance of time as of anatomical character from the Engis skull, and the possibility of its belonging to a distinct race from the latter might reasonably appear to be greatly heightened. "To prevent the possibility of reasoning in a vicious circle, however, I thought it would be well to endeavour to ascertain what amount of cranial variation is to be found in a pure race at the present day; and as the natives of Southern and Western Australia are probably as pure and homogeneous in blood, customs, and language, as any race of savages in existence, I turned to them, the more readily as the Hunterian museum contains a very fine collection of such skulls. "I soon found it possible to select from among these crania two (connected by all sorts of intermediate gradations), the one of which should very nearly resemble the Engis skull, while the other should somewhat less closely approximate the Neanderthal cranium in form, size, and proportions. And at the same time others of these skulls presented no less remarkable affinities with the low type of Borreby skull. "That the resemblances to which I allude are by no means of a merely superficial character, is shown by the accompanying diagram (Figure 6), which gives the contours of the two ancient and of one of the Australian skulls, and by the following table of measurements. TABLE 5/1. COLUMN 1: TYPE OF SKULL. COLUMN 2 (A): The horizontal circumference in the plane of a line joining the glabella with the occipital protuberance. COLUMN 3 (B): The longitudinal arc from the nasal depression along the middle line of the skull to the occipital tuberosity. COLUMN 4 (C): From the level of the glabello-occipital line on each side, across the middle of the sagittal suture to the same point on the opposite side. COLUMN 5 (D): The vertical height from the glabello-occipital line. COLUMN 6 (E): The extreme longitudinal measurement. COLUMN 7 (F): The extreme transverse measurement.* (* I have taken the glabello-occipital line as a base in these measurements, simply because it enables me to compare all the skulls, whether fragments or entire, together. The greatest circumference of the English skull lies in a plane considerably above that of the glabello-occipital line, and amounts to 22 inches.) Engis : 20 1/2: 13 3/4: 12 1/2: 4 3/4: 7 3/4: 5 1/4. Australian, Number 1: 20 1/2: 13 : 12 : 4 3/4: 7 1/2: 5 4/10. Australian, Number 2: 22 : 12 1/2: 10 3/4: 3 8/10: 7.9: 5 3/4. Neanderthal: 23 : 12 : 10 : 3 3/4: 8 : 5 3/4. "The question whether the Engis skull has rather the character of one of the high races or of one of the lower has been much disputed, but the following measurements of an English skull, noted in the catalogue of the Hunterian museum as typically Caucasian (see Figure 4) will serve to show that both sides may be right, and that cranial measurements alone afford no safe indication of race. English : 21 : 13 3/4: 12 1/2: 4 4/10: 7 7/8: 5 1/3. "In making the preceding statement, it must be clearly understood that I neither desire to affirm that the Engis and Neanderthal skulls belong to the Australian race, nor to assert even that the ancient skulls belong to one and the same race, so far as race is measured by language, colour of skin, or character of hair. Against the conclusion that they are of the same race as the Australians various minor anatomical differences of the ancient skulls, such as the great development of the frontal sinuses, might be urged; while against the supposition of either the identity, or the diversity, of race of the two arises the known independence of the variation of cranium on the one hand, and of hair, colour, and language on the other. "But the amount of variation of the Borreby skulls, and the fact that the skulls of one of the purest and most homogeneous of existing races of men can be proved to differ from one another in the same characters, though perhaps not quite to the same extent, as the Engis and Neanderthal skulls, seem to me to prohibit any cautious reasoner from affirming the latter to have been necessarily of distinct races. [Illustration: Figure 6. Outlines of Skulls] (FIGURE 6. OUTLINES OF THE SKULL FROM THE NEANDERTHAL, OF AN AUSTRALIAN SKULL FROM PORT ADELAIDE, AND OF THE SKULL FROM THE CAVE OF ENGIS, DRAWN TO THE SAME ABSOLUTE LENGTH, IN ORDER THE BETTER TO CONTRAST THEIR PROPORTIONS. a. The glabella. b. The occipital protuberance, or the point on the exterior of each skull which corresponds roughly with the attachment of the tentorium, or with the inferior boundary of the posterior cerebral lobes. e. The position of the auditory foramen of the Engis skull.) "The marked resemblances between the ancient skulls and their modern Australian analogues, however, have a profound interest, when it is recollected that the stone axe is as much the weapon and the implement of the modern as of the ancient savage; that the former turns the bones of the kangaroo and of the emu to the same account as the latter did the bones of the deer and the urus; that the Australian heaps up the shells of devoured shellfish in mounds which represent the "refuse-heaps" or "Kjokkenmodding," of Denmark; and, finally, that, on the other side of Torres Straits, a race akin to the Australians are among the few people who now build their houses on pile-works, like those of the ancient Swiss lakes. "That this amount of resemblance in habit and in the conditions of existence is accompanied by as close a resemblance in cranial configuration, illustrates on a great scale that what Cuvier demonstrated of the animals of the Nile valley is no less true of men; circumstances remaining similar, the savage varies little more, it would seem, than the ibis or the crocodile, especially if we take into account the enormous extent of the time over which our knowledge of man now extends, as compared with that measured by the duration of the sepulchres of Egypt. "Finally, the comparatively large cranial capacity of the Neanderthal skull, overlaid though it may be by pithecoid bony walls, and the completely human proportions of the accompanying limb-bones, together with the very fair development of the Engis skull, clearly indicate that the first traces of the primordial stock whence Man has proceeded need no longer be sought, by those who entertain any form of the doctrine of progressive development, in the newest Tertiaries; but that they may be looked for in an epoch more distant from the age of the Elephas primigenius than that is from us." The two skulls which form the subject of the preceding comments and illustrations have given rise to nearly an equal amount of surprise for opposite reasons; that of Engis because being so unequivocally ancient, it approached so near to the highest or Caucasian type; that of the Neanderthal, because, having no such decided claims to antiquity, it departs so widely from the normal standard of humanity. Professor Huxley's observation regarding the wide range of variation, both as to shape and capacity, in the skulls of so pure a race as the native Australian, removes to no small extent this supposed anomaly, assuming what though not proved is very probable, that both varieties co-existed in the Pleistocene period in Western Europe. As to the Engis skull, we must remember that although associated with the elephant, rhinoceros, bear, tiger, and hyaena, all of extinct species, it nevertheless is also accompanied by a bear, stag, wolf, fox, beaver, and many other quadrupeds of species still living. Indeed many eminent palaeontologists, and among them Professor Pictet, think that, numerically considered, the larger portion of the mammalian fauna agrees specifically with that of our own period, so that we are scarcely entitled to feel surprised if we find human races of the Pleistocene epoch undistinguishable from some living ones. It would merely tend to show that Man has been as constant in his osteological characters as many other mammalia now his contemporaries. The expectation of always meeting with a lower type of human skull, the older the formation in which it occurs, is based on the theory of progressive development, and it may prove to be sound; nevertheless we must remember that as yet we have no distinct geological evidence that the appearance of what are called the inferior races of mankind has always preceded in chronological order that of the higher races. It is now admitted that the differences between the brain of the highest races of Man and that of the lowest,* though less in degree, are of the same order as those which separate the human from the simian brain; and the same rule holds good in regard to the shape of the skull. (* "Natural History Review" 1861 page 8.) The average Negro skull differs from that of the European in having a more receding forehead, more prominent superciliary ridges, and more largely developed prominences and furrows for the attachment of muscles; the face also, and its lines, are larger proportionally. The brain is somewhat less voluminous on the average in the lower races of mankind, its convolutions rather less complicated, and those of the two hemispheres more symmetrical, in all which points an approach is made to the simian type. It will also be seen, by reference to the late Dr. Morton's works, and by the foregoing statements of Professor Huxley, that the range of size or capacity between the highest and lowest human brain is greater than that between the highest simian and lowest human brain; but the Neanderthal skull, although in several respects it is more ape-like than any human skull previously discovered, is, in regard to volume, by no means contemptible. Eminent anatomists have shown that in the average proportions of some of the bones the Negro differs from the European, and that in most of these characters, he makes a slightly nearer approach to the anthropoid quadrumana;* but Professor Schaaffhausen has pointed out that in these proportions the Neanderthal skeleton does not differ from the ordinary standard, so that the skeleton by no means indicates a transition between Homo and Pithecus. (* "The inferior races of mankind exhibit proportions which are in many respects intermediate between the higher, or European, orders, and the monkeys. In the Negro, for instance, the stature is less than in the European. The cranium, as is well known, bears a small proportion to the face. Of the extremities the upper are proportionately longer, and there is, in both upper and lower, a less marked preponderance of the proximal over the distal segments. For instance, in the Negro, the thigh and arm are rather shorter than in the European; the leg is actually of equal length in both races, and is therefore, relatively, a little longer in the Negro; the fore-arm in the latter is actually, as well as relatively, a little longer; the foot is an eighth, and the hand a twelfth longer than in the European. It is well known that the foot is less well formed in the Negro than in the European. The arch of the instep, the perfect conformation of which is essential to steadiness and ease of gait, is less elevated in the former than in the latter. The foot is thereby rendered flatter as well as longer, more nearly resembling the monkey's, between which and the European there is a marked difference in this particular."--From "A Treatise on the Human Skeleton" by Dr. Humphry, Lecturer on Surgery and Anatomy in the Cambridge University Medical School, page 91.) There is doubtless, as shown in the diagram Figure 4, a nearer resemblance in the outline of the Neanderthal skull to that of a chimpanzee than had ever been observed before in any human cranium; and Professor Huxley's description of the occipital region shows that the resemblance is not confined to the mere excessive prominence of the superciliary ridges. The direct bearing of the ape-like character of the Neanderthal skull on Lamarck's doctrine of progressive development and transmutation, or on that modification of it which has of late been so ably advocated by Mr. Darwin, consists in this, that the newly observed deviation from a normal standard of human structure is not in a casual or random direction, but just what might have been anticipated if the laws of variation were such as the transmutationists require. For if we conceive the cranium to be very ancient, it exemplifies a less advanced stage of progressive development and improvement. If it be a comparatively modern race, owing its peculiarities of conformation to degeneracy, it is an illustration of what botanists call "atavism," or the tendency of varieties to revert to an ancestral type, which type, in proportion to its antiquity, would be of lower grade. To this hypothesis, of a genealogical connection between Man and the lower animals, I shall again allude in the concluding chapters. [11] CHAPTER 6. -- PLEISTOCENE ALLUVIUM AND CAVE DEPOSITS WITH FLINT IMPLEMENTS. General Position of Drift with extinct Mammalia in Valleys. Discoveries of M. Boucher de Perthes at Abbeville. Flint Implements found also at St. Acheul, near Amiens. Curiosity awakened by the systematic Exploration of the Brixham Cave. Flint Knives in same, with Bones of extinct Mammalia. Superposition of Deposits in the Cave. Visits of English and French Geologists to Abbeville and Amiens. PLEISTOCENE ALLUVIUM CONTAINING FLINT IMPLEMENTS IN THE VALLEY OF THE SOMME. Throughout a large part of Europe we find at moderate elevations above the present river-channels, usually at a height of less than 40 feet, but sometimes much higher, beds of gravel, sand, and loam containing bones of the elephant, rhinoceros, horse, ox, and other quadrupeds, some of extinct, others of living, species, belonging for the most part to the fauna already alluded to in the fourth chapter as characteristic of the interior of caverns. The greater part of these deposits contain fluviatile shells, and have undoubtedly been accumulated in ancient river-beds. These old channels have long since been dry, the streams which once flowed in them having shifted their position, deepening the valleys, and often widening them on one side. It has naturally been asked, if Man co-existed with the extinct species of the caves, why were his remains and the works of his hands never embedded outside the caves in ancient river-gravel containing the same fossil fauna? Why should it be necessary for the geologist to resort for evidence of the antiquity of our race to the dark recesses of underground vaults and tunnels which may have served as places of refuge or sepulture to a succession of human beings and wild animals, and where floods may have confounded together in one breccia the memorials of the fauna of more than one epoch? Why do we not meet with a similar assemblage of the relics of Man, and of living and extinct quadrupeds, in places where the strata can be thoroughly scrutinised in the light of day? Recent researches have at length demonstrated that such memorials, so long sought for in vain, do in fact exist, and their recognition is the chief cause of the more favourable reception now given to the conclusions which MM. Tournal, Christol, Schmerling, and others, arrived at thirty years ago respecting the fossil contents of caverns. [12] A very important step in this new direction was made thirteen years after the publication of Schmerling's researches, by M. Boucher de Perthes, who found in ancient alluvium at Abbeville, in Picardy, some flint implements, the relative antiquity of which was attested by their geological position. The antiquarian knowledge of their discoverer enabled him to recognise in their rude and peculiar type a character distinct from that of the polished stone weapons of a later period, usually called "celts." In the first volume of his "Antiquites Celtiques," published in 1847, M. Boucher de Perthes styled these older tools "antediluvian," because they came from the lowest beds of a series of ancient alluvial strata bordering the valley of the Somme, which geologists had termed "diluvium." He had begun to collect these implements in 1841. From that time they had been annually dug out of the drift or deposits of gravel and sand, of which fine sections were laid open from 20 to 35 feet in depth, whenever excavations were made in repairing the fortifications of Abbeville; or as often as flints were wanted for the roads, or loam for making bricks. For years previously bones of quadrupeds of the genera elephant, rhinoceros, bear, hyaena, stag, ox, horse, and others, had been collected there, and sent from time to time to Paris to be examined and named by Cuvier, who had described them in his Ossements Fossiles. A correct account of the associated flint tools and of their position was given in 1847 by M. Boucher de Perthes in his work above cited, and they were stated to occur at various depths, often 20 or 30 feet from the surface, in sand and gravel, especially in those strata which were nearly in contact with the subjacent white Chalk. But the scientific world had no faith in the statement that works of art, however rude, had been met with in undisturbed beds of such antiquity. Few geologists visited Abbeville in winter, when the sand-pits were open, and when they might have opportunities of verifying the sections, and judging whether the instruments had really been embedded by natural causes in the same strata with the bones of the mammoth, rhinoceros, and other extinct mammalia. Some of the tools figured in the "Antiquites Celtiques" were so rudely shaped, that many imagined them to have owed their peculiar forms to accidental fracture in a river's bed; others suspected frauds on the part of the workmen, who might have fabricated them for sale, or that the gravel had been disturbed, and that the worked flints had got mingled with the bones of the mammoth long after that animal and its associates had disappeared from the earth. No one was more sceptical than the late eminent physician of Amiens, Dr. Rigollot, who had long before (in the year 1819) written a memoir on the fossil mammalia of the valley of the Somme. He was at length induced to visit Abbeville, and, having inspected the collection of M. Boucher de Perthes, returned home resolved to look for himself for flint tools in the gravel-pits near Amiens. There, accordingly, at a distance of about 30 miles from Abbeville, he immediately found abundance of similar flint implements, precisely the same in the rudeness of their make, and the same in their geological position; some of them in gravel nearly on a level with the Somme, others in similar deposits resting on Chalk at a height of about 90 feet above the river. Dr. Rigollot having in the course of four years obtained several hundred specimens of these tools, most of them from St. Acheul in the south-east suburbs of Amiens, lost no time in communicating an account of them to the scientific world, in a memoir illustrated by good figures of the worked flints and careful sections of the beds. These sections were executed by M. Buteux, an engineer well qualified for the task, who had written a good description of the geology of Picardy. Dr. Rigollot, in this memoir, pointed out most clearly that it was not in the vegetable soil, nor in the brick-earth with land and freshwater shells next below, but in the lower beds of coarse flint-gravel, usually 12, 20, or 25 feet below the surface, that the implements were met with, just as they had been previously stated by M. Boucher de Perthes to occur at Abbeville. The conclusion, therefore, which was legitimately deduced from all the facts, was that the flint tools and their fabricators were coeval with the extinct mammalia embedded in the same strata. BRIXHAM CAVE, NEAR TORQUAY, DEVONSHIRE. Four years after the appearance of Dr. Rigollot's paper, a sudden change of opinion was brought about in England respecting the probable co-existence, at a former period, of Man and many extinct mammalia, in consequence of the results obtained from a careful exploration of a cave at Brixham, near Torquay, in Devonshire. As the new views very generally adopted by English geologists had no small influence on the subsequent progress of opinion in France, I shall interrupt my account of the researches made in the valley of the Somme, by a brief notice of those which were carried on in 1858 in Devonshire with more than usual care and scientific method. Dr. Buckland, in his celebrated work, entitled "Reliquiae Diluvianae," published in 1823, in which he treated of the organic remains contained in caves, fissures, and "diluvial gravel" in England, had given a clear statement of the results of his own original observations, and had declared that none of the human bones or stone implements met with by him in any of the caverns could be considered to be as old as the mammoth and other extinct quadrupeds. Opinions in harmony with this conclusion continued until very lately to be generally in vogue in England; although about the time that Schmerling was exploring the Liege caves, the Reverend Mr. McEnery, a Catholic priest, residing near Torquay, had found in a cave one mile east of that town, called "Kent's Hole," in red loam covered with stalagmite, not only bones of the mammoth, tichorhine rhinoceros, hippopotamus, cave-bear, and other mammalia, but several remarkable flint tools, some of which he supposed to be of great antiquity, while there were also remains of Man in the same cave of a later date.* (* The manuscript and plates prepared for a joint memoir on Kent's Hole, by Mr. McEnery and Dr. Buckland, have recently been published by Mr. Vivian of Torquay, from which, as well as from some of the unprinted manuscript, I infer that Mr. McEnery only refrained out of deference to Dr. Buckland from declaring his belief in the contemporaneousness of certain flint implements of an antique type and the bones of extinct animals. Two of these implements from Kent's Hole, figured in Plate 12 of the posthumous work above alluded to, approach very closely in form and size to the common Abbeville implements.) About ten years afterwards, in a "Memoir on the Geology of South Devon," published in 1842 by the Geological Society of London,* an able geologist, Mr. Godwin-Austen, declared that he had obtained in the same cave (Kent's Hole) works of Man from undisturbed loam or clay, under stalagmite, mingled with the remains of extinct animals, and that all these must have been introduced "before the stalagmite flooring had been formed." He maintained that such facts could not be explained away by the hypothesis of sepulture, as in Dr. Buckland's well-known case of the human skeleton of Paviland, because in the Devon cave the flint implements were widely distributed through the loam, and lay beneath the stalagmite. (* "Transactions of the Geological Society" 2nd series volume 6 page 444.) As the osseous and other contents of Kent's Hole had, by repeated diggings, been thrown into much confusion, it was thought desirable in 1858, when a new and intact bone-cave was discovered at Brixham, about four miles south of Torquay, to have a thorough and systematic examination made of it. The Royal Society, chiefly at the instance of Dr. Falconer, made two grants towards defraying the expenses, and Miss Burdett-Coutts contributed liberally towards the same object. A committee of geologists was charged with the investigations, among whom Dr. Falconer and Mr. Prestwich took a prominent part, visiting Torquay while the excavations were in progress. Mr. Pengelly, another member of the committee, well qualified for the task by nearly twenty years' previous experience in cave explorations, zealously directed and superintended the work. By him, in 1859, I was conducted through the subterranean galleries after they had been cleared out; and Dr. Falconer, who was also at Torquay, showed me the numerous fossils which had been discovered, and which he was then studying, all numbered and labelled, with reference to a journal in which the geological position of each specimen was recorded with scrupulous care. The discovery of the existence of this suite of caverns near the sea at Brixham was made accidentally by the roof of one of them being broken through in quarrying. None of the four external openings now exposed to view in steep cliffs or in the sloping side of a valley were visible before the breccia and earthy matter which blocked them up were removed during the late exploration. According to a ground-plan drawn up by Professor Ramsay, it appears that some of the passages which run nearly north and south are fissures connected with the vertical dislocation of the rocks, while another set, running nearly east and west, are tunnels, which have the appearance of having been to a great extent hollowed out by the action of running water. The central or main entrance, leading to what is called the "reindeer gallery," because a perfect antler of that animal was found sticking in the stalagmitic floor, is 95 feet above the level of the sea, being also 78 above the bottom of the adjoining valley. The united length of the galleries which were cleared out amounted to several hundred feet. Their width never exceeded 8 feet. They were sometimes filled up to the roof with mud, but occasionally there was a considerable space between the roof and floor. The latter, in the case of the fissure-caves, was covered with stalagmite, but in the tunnels it was usually free from any such incrustation. The following was the general succession of the deposits forming the contents of the underground passages and channels:-- First. At the top, a layer of stalagmite varying in thickness from 1 to 15 inches, which sometimes contained bones, such as the reindeer's horn, already mentioned, and an entire humerus of the cave-bear. Secondly. Next below, loam or bone-earth, of an ochreous red colour, with angular stones and some pebbles, from 2 to 13 feet in thickness. Thirdly. At the bottom of all, gravel with many rounded pebbles in it. This was everywhere removed so long as the tunnels which narrowed downwards were wide enough to be worked. It proved to be almost entirely barren of fossils. The mammalia obtained from the bone-earth consisted of Elephas primigenius, or mammoth; Rhinoceros tichorhinus; Ursus spelaeus; Hyaena spelaea; Felis spelaea, or the cave-lion; Cervus tarandus, or the reindeer; a species of horse, ox, and several rodents, and others not yet determined. No human bones were obtained anywhere during these excavations, but many flint knives, chiefly from the lowest part of the bone-earth; and one of the most perfect lay at the depth of 13 feet from the surface, and was covered with bone-earth of that thickness. Neglecting the less perfect specimens, some of which were met with even in the lowest gravel, about fifteen knives, recognised as artificially formed by the most experienced antiquaries, were taken from the bone-earth, and usually from near the bottom. Such knives, considered apart from the associated mammalia, afford in themselves no safe criterion of antiquity, as they might belong to any part of the age of stone, similar tools being sometimes met with in tumuli posterior in date to the era of the introduction of bronze. But the contemporaneity of those at Brixham with the extinct animals is demonstrated not only by the occurrence at one point in overlying stalagmite of the bone of a cave-bear, but also by the discovery at the same level in the bone-earth, and in close proximity to a very perfect flint tool, of the entire left hind-leg of a cave-bear. This specimen, which was shown me by Dr. Falconer and Mr. Pengelly, was exhumed from the earthy deposit in the reindeer gallery, near its junction with the flint-knife gallery, at the distance of about sixty-five feet from the main entrance. The mass of earth containing it was removed entire, and the matrix cleared away carefully by Dr. Falconer in the presence of Mr. Pengelly. Every bone was in its natural place, the femur, tibia, fibula, ankle-bone, or astragalus, all in juxtaposition. Even the patella or detached bone of the knee-pan was searched for, and not in vain. Here, therefore, we have evidence of an entire limb not having been washed in a fossil state out of an older alluvium, and then swept afterwards into a cave, so as to be mingled with flint implements, but having been introduced when clothed with its flesh, or at least when it had the separate bones bound together by their natural ligaments, and in that state buried in mud. If they were not all of contemporary date, it is clear from this case, and from the humerus of the Ursus spelaeus, before cited, as found in a floor of stalagmite, that the bear lived after the flint tools were manufactured, or in other words, that Man in this district preceded the cave-bear. A glance at the position of Windmill Hill, in which the caverns are situated, and a brief survey of the valleys which bound it on three sides, are enough to satisfy a geologist that the drainage and geographical features of this region have undergone great changes since the gravel and bone-earth were carried by streams into the subterranean cavities above described. Some worn pebbles of haematite, in particular, can only have come from their nearest parent rock, at a period when the valleys immediately adjoining the caves were much shallower than they now are. The reddish loam in which the bones are embedded is such as may be seen on the surface of limestone in the neighbourhood, but the currents which were formerly charged with such mud must have run at a level 78 feet above that of the stream now flowing in the same valley. It was remarked by Mr. Pengelly that the stones and bones in the loam had their longest axes parallel to the direction of the tunnels and fissures, showing that they were deposited by the action of a stream.* (* Pengelly, "Geologist" volume 4 1861 page 153.) It appears that so long as the flowing water had force enough to propel stony fragments, no layer of fine mud could accumulate, and so long as there was a regular current capable of carrying in fine mud and bones, no superficial crust of stalagmite. In some passages, as before stated, stalagmite was wanting, while in one place seven or eight alternations of stalagmite and loam were observed, seeming to indicate a prevalence of more rainy seasons, succeeded by others, when the water was for a time too low to flood the area where the calcareous incrustation accumulated. If the regular sequence of the three deposits of pebbles, mud, and stalagmite was the result of the causes above explained, the order of superposition would be constant, yet we could not be sure that the gravel in one passage might not sometimes be coeval with the bone-earth or stalagmite in another. If therefore the flint knives had not been very widely dispersed, and if one of them had not been at the bottom of the bone-earth, close to the leg of the bear above described, their antiquity relatively to the extinct mammalia might have been questioned. No coprolites were found in the Brixham excavations, and very few gnawed bones. These few may have been brought from some distance before they reached their place of rest. Upon the whole, the same conclusion which Dr. Schmerling came to, respecting the filling up of the caverns near Liege, seems applicable to the caves of Brixham. Dr. Falconer, after aiding in the investigations above alluded to near Torquay, stopped at Abbeville on his way to Sicily, in the autumn of 1858, and saw there the collection of M. Boucher de Perthes. Being at once satisfied that the flints called hatchets had really been fashioned by the hand of Man, he urged Mr. Prestwich, by letter, thoroughly to explore the geology of the valley of the Somme. This he accordingly accomplished, in company with Mr. John Evans [13], of the Society of Antiquaries, and, before his return that same year, succeeded in dissipating all doubts from the minds of his geological friends by extracting, with his own hands, from a bed of undisturbed gravel, at St. Acheul, a well-shaped flint hatchet. This implement was buried in the gravel at a depth of 17 feet from the surface, and was lying on its flat side. There were no signs of vertical rents in the enveloping matrix, nor in the overlying beds of sand and loam, in which were many land and freshwater shells; so that it was impossible to imagine that the tool had gradually worked its way downwards, as some had suggested, through the incumbent soil, into an older formation.* (* Prestwich, "Proceedings of the Royal Society" 1859 and "Philosophical Transactions" 1860.) There was no one in England whose authority deserved to have so much weight in overcoming incredulity in regard to the antiquity of the implements in question. For Mr. Prestwich, besides having published a series of important memoirs on the Tertiary formations of Europe, had devoted many years specially to the study of the drift and its organic remains. His report, therefore, to the Royal Society, accompanied by a photograph showing the position of the flint tool in situ before it was removed from its matrix, not only satisfied many inquirers, but induced others to visit Abbeville and Amiens; and one of these, Mr. Flower, who accompanied Mr. Prestwich on his second excursion to St. Acheul, in June 1859, succeeded, by digging into the bank of gravel, in disinterring, at the depth of 22 feet from the surface, a fine, symmetrically-shaped weapon of an oval form, lying in and beneath strata which were observed by many witnesses to be perfectly undisturbed.* (* "Quarterly Journal of the Geological Society" volume 16 1860 page 190.) Shortly afterwards, in the year 1859, I visited the same pits, and obtained seventy flint tools, one of which was taken out while I was present, though I did not see it before it had fallen from the matrix. I expressed my opinion in favour of the antiquity of the flint tools to the meeting of the British Association at Aberdeen, in the same year.* (* See "Report of British Association" for 1859. ) On my way through Rouen, I stated my convictions on this subject to M. George Pouchet, who immediately betook himself to St. Acheul, commissioned by the municipality of Rouen, and did not quit the pits till he had seen one of the hatchets extracted from gravel in its natural position.* (* "Actes du Musee d'Histoire Naturelle de Rouen" 1860 page 33.) M. Gaudry also gave the following account of his researches in the same year to the Royal Academy of Sciences at Paris. "The great point was not to leave the workmen for a single instant, and to satisfy oneself by actual inspection whether the hatchets were found in situ. I caused a deep excavation to be made, and found nine hatchets, most distinctly in situ in the diluvium, associated with teeth of Equus fossilis and a species of Bos, different from any now living, and similar to that of the diluvium and of caverns."* (* "Comptes rendus" September 26 and October 3, 1859.) In 1859, M. Hebert, an original observer of the highest authority, declared to the Geological Society of France that he had, in 1854, or four years before Mr. Prestwich's visit to St. Acheul, seen the sections at Abbeville and Amiens, and had come to the opinion that the hatchets were imbedded in the "lower diluvium," and that their origin was as ancient as that of the mammoth and the rhinoceros. M. Desnoyers also made excavations after M. Gaudry, at St. Acheul, in 1859, with the same results.* (* "Bulletin" volume 17 page 18.) After a lively discussion on the subject in England and France, it was remembered, not only that there were numerous recorded cases leading to similar conclusions in regard to cavern deposits, but, also, that Mr. Frere had, so long ago as 1797, found flint weapons, of the same type as those of Amiens, in a freshwater formation in Suffolk, in conjunction with elephant remains; and nearly a hundred years earlier (1715), another tool of the same kind had been exhumed from the gravel of London, together with bones of an elephant; to all which examples I shall allude more fully in the sequel. I may conclude this chapter by quoting a saying of Professor Agassiz, "that whenever a new and startling fact is brought to light in science, people first say, 'it is not true,' then that 'it is contrary to religion,' and lastly, 'that everybody knew it before.'" If I were considering merely the cultivators of geology, I should say that the doctrine of the former co-existence of Man with many extinct mammalia had already gone through these three phases in the progress of every scientific truth towards acceptance. But the grounds of this belief have not yet been fully laid before the general public, so as to enable them fairly to weigh and appreciate the evidence. I shall therefore do my best in the next three chapters to accomplish this task. CHAPTER 7. -- PEAT AND PLEISTOCENE ALLUVIUM OF THE VALLEY OF THE SOMME. Geological Structure of the Valley of the Somme and of the surrounding Country. Position of Alluvium of different Ages. Peat near Abbeville. Its animal and vegetable Contents. Works of Art in Peat. Probable Antiquity of the Peat, and Changes of Level since its Growth began. Flint Implements of antique Type in older Alluvium. Their various Forms and great Numbers. GEOLOGICAL STRUCTURE OF THE SOMME VALLEY. The valley of the Somme in Picardy, alluded to in the last chapter, is situated geologically in a region of white Chalk with flints, the strata of which are nearly horizontal. The Chalk hills which bound the valley are almost everywhere between 200 and 300 feet in height. On ascending to that elevation, we find ourselves on an extensive table-land, in which there are slight elevations and depressions. The white Chalk itself is scarcely ever exposed at the surface on this plateau, although seen on the slopes of the hills, as at b and c (Figure 7). The general surface of the upland region is covered continuously for miles in every direction by loam or brick-earth (Number 4), about 5 feet thick, devoid of fossils. To the wide extent of this loam the soil of Picardy chiefly owes its great fertility. Here and there we also observe, on the Chalk, outlying patches of Tertiary sand and clay (Number 5, Figure 7), with Eocene fossils, the remnants of a formation once more extensive, and which probably once spread in one continuous mass over the Chalk, before the present system of valleys had begun to be shaped out. It is necessary to allude to these relics of Tertiary strata, of which the larger part is missing, because their denudation has contributed largely to furnish the materials of gravels in which the flint implements and bones of extinct mammalia are entombed. From this source have been derived not only the regular-formed egg-shaped pebbles, so common in the old fluviatile alluvium at all levels, but those huge masses of hard sandstone, several feet in diameter, to which I shall allude in the sequel. The upland loam also (Number 4) has often, in no slight degree, been formed at the expense of the same Tertiary sands and clays, as is attested by its becoming more or less sandy or argillaceous, according to the nature of the nearest Eocene outlier in the neighbourhood. The average width of the valley of the Somme between Amiens and Abbeville is one mile. The height, therefore, of the hills, in relation to the river-plain, could not be correctly represented in the annexed diagram (Figure 7), as they would have to be reduced in altitude; or if not, it would be necessary to make the space between c and b four times as great. The dimensions also of the masses, of drift or alluvium, 2 and 3, have been exaggerated, in order to render them sufficiently conspicuous; for, all important as we shall find them to be as geological monuments of the Pleistocene period, they form a truly insignificant feature in the general structure of the country, so much so, that they might easily be overlooked in a cursory survey of the district, and are usually unnoticed in geological maps not specially devoted to the superficial formations. [Illustration: Figure 7. Valley of the Somme] (FIGURE 7. SECTION ACROSS THE VALLEY OF THE SOMME IN PICARDY. 1. Peat, 20 to 30 feet thick, resting on gravel, a. 2. Lower level gravel with elephants' bones and flint tools, covered with fluviatile loam, 20 to 40 feet thick. 3. Higher level gravel with similar fossils, and with overlying loam, in all 30 feet thick. 4. Upland loam without shells (Limon des plateaux), 5 or 6 feet thick. 5. Eocene strata, resting on the Chalk in patches.) It will be seen by the description given of the section (Figure 7) that Number 2 indicates the lower level gravels, and Number 3 the higher ones, or those rising to elevations of 80 or 100 feet above the river. Newer than these is the peat Number 1, which is from 10 to 30 feet in thickness, and which is not only of later date than the alluvium, 2 and 3, but is also posterior to the denudation of those gravels, or to the time when the valley was excavated through them. Underneath the peat is a bed of gravel, a, from 3 to 14 feet thick, which rests on undisturbed Chalk. This gravel was probably formed, in part at least, when the valley was scooped out to its present depth, since which time no geological change has taken place, except the growth of the peat, and certain oscillations in the general level of the country, to which we shall allude by and by. A thin layer of impervious clay separates the gravel a from the peat Number 1, and seems to have been a necessary preliminary to the growth of the peat. PEAT OF THE VALLEY OF THE SOMME. As hitherto, in our retrospective survey, we have been obliged, for the sake of proceeding from the known to the less known, to reverse the natural order of history, and to treat of the newer before the older formations, I shall begin my account of the geological monuments of the valley of the Somme by saying something of the most modern of all of them, the peat. This substance occupies the lower parts of the valley far above Amiens, and below Abbeville as far as the sea. It has already been stated to be in some places 30 feet thick, and is even occasionally more than 30 feet, corresponding in that respect to the Danish mosses before described (Chapter 2). Like them, it belongs to the Recent period; all the embedded mammalia, as well as the shells, being of the same species as those now inhabiting Europe. The bones of quadrupeds are very numerous, as I can bear witness, having seen them brought up from a considerable depth near Abbeville, almost as often as the dredging instrument was used. Besides remains of the beaver, I was shown, in the collection of M. Boucher de Perthes, two perfect lower jaws with teeth of the bear, Ursus arctos; and in the Paris Museum there is another specimen, also from the Abbeville peat. The list of mammalia already comprises a large proportion of those proper to the Swiss lake-dwellings, and to the shell-mounds and peat of Denmark; but unfortunately as yet no special study has been made of the French fauna, like that by which the Danish and Swiss zoologists and botanists have enabled us to compare the wild and tame animals and the vegetation of the age of stone with that of the age of iron. Notwithstanding the abundance of mammalian bones in the peat, and the frequency of stone implements of the Celtic and Gallo-Roman periods, M. Boucher de Perthes has only met with three or four fragments of human skeletons. At some depth in certain places in the valley near Abbeville, the trunks of alders have been found standing erect as they grew, with their roots fixed in an ancient soil, afterwards covered with peat. Stems of the hazel, and nuts of the same, abound; trunks, also, of the oak and walnut. The peat extends to the coast, and is there seen passing under the sand-dunes and below the sea-level. At the mouth of the river Canche, which joins the sea near the embouchure of the Somme, yew trees, firs, oaks, and hazels have been dug out of peat, which is there worked for fuel, and is about three feet thick.* (* D'Archiac, "Histoire des Progres" volume 2 page 154.) During great storms, large masses of compact peat, enclosing trunks of flattened trees, have been thrown up on the coast at the mouth of the Somme; seeming to indicate that there has been a subsidence of the land and a consequent submergence of what was once a westward continuation of the valley of the Somme into what is now a part of the English Channel. Whether the vegetation of the lowest layers of peat differed as to the geographical distribution of some of the trees from the middle, and this from the uppermost peat, as in Denmark, has not yet been ascertained; nor have careful observations been made with a view of calculating the minimum of time which the accumulation of so dense a mass of vegetable matter must have taken. A foot in thickness of highly compressed peat, such as is sometimes reached in the bottom of the bogs, is obviously the equivalent in time of a much greater thickness of peat of spongy and loose texture, found near the surface. The workmen who cut peat, or dredge it up from the bottom of swamps and ponds, declare that in the course of their lives none of the hollows which they have found, or caused by extracting peat, have ever been refilled, even to a small extent. They deny, therefore, that the peat grows. This, as M. Boucher de Perthes observes, is a mistake; but it implies that the increase in one generation is not very appreciable by the unscientific. The antiquary finds near the surface Gallo-Roman remains, and still deeper Celtic weapons of the stone period. [14] But the depth at which Roman works of art occur varies in different places, and is no sure test of age; because in some parts of the swamps, especially near the river, the peat is often so fluid that heavy substances may sink through it, carried down by their own gravity. In one case, however, M. Boucher de Perthes observed several large flat dishes of Roman pottery, lying in a horizontal position in the peat, the shape of which must have prevented them from sinking or penetrating through the underlying peat. Allowing about fourteen centuries for the growth of the superincumbent vegetable matter, he calculated that the thickness gained in a hundred years would be no more than three centimetres.* (* "Antiquites Celtiques" volume 2 page 134.) This rate of increase would demand so many thousands of years for the formation of the entire thickness of 30 feet that we must hesitate before adopting it as a chronometric scale. Yet, by multiplying observations of this kind, and bringing one to bear upon and check another, we may eventually succeed in obtaining data for estimating the age of the peaty deposit. [15] The rate of increase in Denmark may not be applicable to France; because differences in the humidity of the climate, or in the intensity and duration of summer's heat and winter's cold, as well as diversity in the species of plants which most abound, would cause the peat to grow more or less rapidly, not only when we compare two distinct countries in Europe, but the same country at two successive periods. I have already alluded to some facts which favour the idea that there has been a change of level on the coast since the peat began to grow. This conclusion seems confirmed by the mere thickness of peat at Abbeville, and the occurrence of alder and hazel-wood near the bottom of it. If 30 feet of peat were now removed, the sea would flow up and fill the valley for miles above Abbeville. Yet this vegetable matter is all of supra-marine origin, for where shells occur in it they are all of terrestrial or fluviatile kinds, so that it must have grown above the sea-level when the land was more elevated than now. We have already seen what changes in the relative level of sea and land have occurred in Scotland subsequently to the time of the Romans, and are therefore prepared to meet with proofs of similar movements in Picardy. In that country they have probably not been confined simply to subsidence, but have comprised oscillations in the level of the land, by which marine shells of the Pleistocene period have been raised some 10 feet or more above the level of the sea. Small as is the progress hitherto made in interpreting the pages of the peaty record, their importance in the valley of the Somme is enhanced by the reflection that, whatever be the number of centuries to which they relate, they belong to times posterior to the ancient implement-bearing beds, which we are next to consider, and are even separated from them, as we shall see, by an interval far greater than that which divides the earliest strata of the peat from the latest. FLINT IMPLEMENTS OF THE PLEISTOCENE PERIOD IN THE VALLEY OF THE SOMME. The alluvium of the valley of the Somme exhibits nothing extraordinary or exceptional in its position or external appearance, nor in the arrangement or composition of its materials, nor in its organic remains; in all these characters it might be matched by the drift of a hundred other valleys in France or England. Its claim to our peculiar attention is derived from the wonderful number of flint tools, of a very antique type, which, as stated in the last chapter, occur in undisturbed strata, associated with the bones of extinct quadrupeds. As much doubt has been cast on the question, whether the so-called flint hatchets have really been shaped by the hands of Man, it will be desirable to begin by satisfying the reader's mind on that point, before inviting him to study the details of sections of successive beds of mud, sand, and gravel, which vary considerably even in contiguous localities. Since the spring of 1859, I have paid three visits to the Valley of the Somme, and examined all the principal localities of these flint tools. In my excursions around Abbeville, I was accompanied by M. Boucher de Perthes, and during one of my explorations in the Amiens district, by Mr. Prestwitch. The first time I entered the pits at St. Acheul, I obtained seventy flint instruments, all of them collected from the drift in the course of the preceding five or six weeks. The two prevailing forms of these tools are represented in the annexed Figures 8 and 9, each of which are half the size of the originals; the first being the spear-headed form, varying in length from six to eight inches; the second, the oval form, which is not unlike some stone implements, used to this day as hatchets and tomahawks by natives of Australia, but with this difference, that the edge in the Australian weapons (as in the case of those called celts in Europe) has been produced by friction, whereas the cutting edge in the old tools of the valley of the Somme was always gained by the simple fracture of the flint, and by the repetition of many dexterous blows. The oval-shaped Australian weapons, however, differ in being sharpened at one end only. The other, though reduced by fracture to the same general form, is left rough, in which state it is fixed into a cleft stick, which serves as a handle. To this it is firmly bound by thin straps of opossum's hide. One of these tools, now in my possession, was given me by Mr. Farquharson of Haughton, who saw a native using it in 1854 on the Auburn river, in Burnet district, North Australia. Out of more than a hundred flint implements which I obtained at St. Acheul, not a few had their edges more or less fractured or worn, either by use as instruments before they were buried in gravel, or by being rolled in the river's bed. Some of these tools were probably used as weapons, both of war and of the chase, others to grub up roots, cut down trees, and scoop out canoes. Some of them may have served, as Mr. Prestwich has suggested, for cutting holes in the ice both for fishing and for obtaining water, as will be explained in the eighth chapter when we consider the arguments in favour of the higher level drift having belonged to a period when the rivers were frozen over for several months every winter. [Illustration: Figure 8. Flint Implement] (FIGURE 8. FLINT IMPLEMENT FROM ST. ACHEUL, NEAR AMIENS, OF THE SPEAR-HEAD SHAPE (half the size of the original, which is 7 1/2 inches long). a. Side view. b. Same seen edgewise. These spear-headed implements have been found in greater number, proportionally to the oval ones, in the upper level gravel at St. Acheul, than in any of the lower gravels in the valley of the Somme. In these last the oval form predominates, especially at Abbeville.) When the natural form of a Chalk-flint presented a suitable handle at one end, as in the specimen, Figure 10, that part was left as found. The portion, for example, between b and c has probably not been altered; the protuberances which are fractured having been broken off by river action before the flint was chipped artificially. The other extremity, a, has been worked till it acquired a proper shape and cutting edge. [Illustration: Figures 9 and 10. Flint Implements] (FIGURES 9 AND 10. FLINT IMPLEMENTS FROM THE PLEISTOCENE DRIFT OF ABBEVILLE AND AMIENS. FIGURE 9. a. OVAL-SHAPED FLINT HATCHET FROM MAUTORT, NEAR ABBEVILLE, half size of original, which is 5 1/2 inches long, from a bed of gravel underlying the fluvio-marine stratum. b. Same seen edgewise. c. Shows a recent fracture of the edge of the same at the point a, or near the top. This portion of the tool, c, is drawn of the natural size, the black central part being the unaltered flint, the white outer coating, the layer which has been formed by discoloration or bleaching since the tool was first made. The entire surface of Number 9 must have been black when first shaped, and the bleaching to such a depth must have been the work of time, whether produced by exposure to the sun and air before it was embedded, or afterwards when it lay deep in the soil. FIGURE 10. FLINT TOOL FROM ST. ACHEUL, seen edgewise; original 6 1/2 inches long, and 3 inches wide. b, c. Portion not artificially shaped. a, b. Part chipped into shape, and having a cutting edge at a.) Many of the hatchets are stained of an ochreous-yellow colour, when they have been buried in yellow gravel, others have acquired white or brown tints, according to the matrix in which they have been enclosed. This accordance in the colouring of the flint tools with the character of the bed from which they have come, indicates, says Mr. Prestwich, not only a real derivation from such strata, but also a sojourn therein of equal duration to that of the naturally broken flints forming part of the same beds.* (* "Philosophical Transactions" 1861 page 297.) [Illustration: Figures 11, 12 and 13. Dendrites on Fling Hatchets] (FIGURES 11, 12 AND 13. DENDRITES ON SURFACES OF FLINT HATCHETS IN THE DRIFT OF ST. ACHEUL, NEAR AMIENS. FIGURE 11. a. Natural size. FIGURE 12. b. Natural size. c. Magnified. FIGURE 13. d. Natural size. e. Magnified.) The surface of many of the tools is encrusted with a film of carbonate of lime, while others are adorned by those ramifying crystallisations called dendrites (see Figures 11, 12 and 13), usually consisting of the mixed oxides of iron and manganese, forming extremely delicate blackish brown sprigs, resembling the smaller kinds of sea weed. They are a useful test of antiquity when suspicions are entertained of the workmen having forged the hatchets which they offer for sale. The most general test, however, of the genuineness of the implements obtained by purchase is their superficial varnish-like or vitreous gloss, as contrasted with the dull aspect of freshly fractured flints. I also remarked, during each of my three visits to Amiens, that there were some extensive gravel-pits, such as those of Montiers and St. Roch, agreeing in their geological character with those of St. Acheul, and only a mile or two distant, where the workmen, although familiar with the forms, and knowing the marketable value of the articles above described, assured me that they had never been able to find a single implement. Respecting the authenticity of the tools as works of art, Professor Ramsay, than whom no one could be a more competent judge, observes: "For more than twenty years, like others of my craft, I have daily handled stones, whether fashioned by nature or art; and the flint hatchets of Amiens and Abbeville seem to me as clearly works of art as any Sheffield whittle."* (* "Athenaeum" July 16, 1859.) Mr. Evans classifies the implements under three heads, two of which, the spear heads and the oval or almond-shaped kinds, have already been described. The third form (Figure 14) consists of flakes, apparently intended for knives or some of the smaller ones for arrow heads. [Illustration: Figure 14. Flint Knife or Flake] (FIGURE 14. FLINT KNIFE OR FLAKE FROM BELOW THE SAND CONTAINING CYRENA FLUMINALIS. MENCHECOURT, ABBEVILLE. d. Transverse section along the line of fracture, b, c. Size, two-thirds of the original.) In regard to their origin, Mr. Evans observes that there is a uniformity of shape, a correctness of outline, and a sharpness about the cutting edges and points, which cannot be due to anything but design.* (* "Archaeologia" volume 38.) Of these knives and flakes, I obtained several specimens from a pit which I caused to be dug at Abbeville, in sand in contact with the Chalk, and below certain fluvio-marine beds, which will be alluded to in the next chapter. Between the spear-head and oval shapes, there are various intermediate gradations, and there are also a vast variety of very rude implements, many of which may have been rejected as failures, and others struck off as chips in the course of manufacturing the more perfect ones. Some of these chips can only be recognised by an experienced eye as bearing marks of human workmanship. It has often been asked, how, without the use of metallic hammers, so many of these oval and spear-headed tools could have been wrought into so uniform a shape. Mr. Evans, in order experimentally to illustrate the process, constructed a stone hammer, by mounting a pebble in a wooden handle, and with this tool struck off flakes from the edge on both sides of a Chalk flint, till it acquired precisely the same shape as the oval tool, Figure 9. If I were invited to estimate the probable number of the more perfect tools found in the valley of the Somme since 1842, rejecting all the knives, and all that might be suspected of being spurious or forged, I should conjecture that they far exceeded a thousand. Yet it would be a great mistake to imagine that an antiquary or geologist, who should devote a few weeks to the exploration of such a valley as that of the Somme, would himself be able to detect a single specimen. But few tools were lying on the surface. The rest have been exposed to view by the removal of such a volume of sand, clay, and gravel, that the price of the discovery of one of them could only be estimated by knowing how many hundred labourers have toiled at the fortifications of Abbeville, or in the sand and gravel pits near that city, and around Amiens, for road materials and other economic purposes, during the last twenty years. [Illustration: Figure 15. Fossils of the White Chalk] (FIGURE 15. FOSSILS OF THE WHITE CHALK. a, b. Coscinopora globularis, D'Orbigny. Orbitolina concava, Parker and Jones. c. Part of same magnified.) In the gravel pits of St. Acheul, and in some others near Amiens, small round bodies, having a tubular cavity in the centre, occur. They are well known as fossils of the White Chalk. Dr. Rigollot suggested that they might have been strung together as beads, and he supposed the hole in the middle to have been artificial. Some of these round bodies are found entire in the Chalk and in the gravel, others have naturally a hole passing through them, and sometimes one or two holes penetrating some way in from the surface, but not extending to the other side. Others, like b, Figure 15, have a large cavity, which has a very artificial aspect. It is impossible to decide whether they have or have not served as personal ornaments, recommended by their globular form, lightness, and by being less destructible than ordinary Chalk. Granting that there were natural cavities in the axis of some of them, it does not follow that these may not have been taken advantage of for stringing them as beads, while others may have been artificially bored through. Dr. Rigollot's argument in favour of their having been used as necklaces or bracelets, appears to me a sound one. He says he often found small heaps or groups of them in one place, all perforated, just as if, when swept into the river's bed by a flood, the bond which had united them together remained unbroken.* (* Rigollot, "Memoire sur des Instruments en Silex" etc., Amiens 1854 page 16.) CHAPTER 8. -- PLEISTOCENE ALLUVIUM WITH FLINT IMPLEMENTS OF THE VALLEY OF THE SOMME--CONCLUDED. Fluvio-marine Strata, with Flint Implements, near Abbeville. Marine Shells in same. Cyrena fluminalis. Mammalia. Entire Skeleton of Rhinoceros. Flint Implements, why found low down in Fluviatile Deposits. Rivers shifting their Channels. Relative Ages of higher and lower-level Gravels. Section of Alluvium of St. Acheul. Two Species of Elephant and Hippopotamus coexisting with Man in France. Volume of Drift, proving Antiquity of Flint Implements. Absence of Human Bones in tool-bearing Alluvium, how explained. Value of certain Kinds of negative Evidence tested thereby. Human Bones not found in drained Lake of Haarlem. In the section of the valley of the Somme given in Figure 7, the successive formations newer than the Chalk are numbered in chronological order, beginning with the most modern, or the peat, which is marked Number 1, and which has been treated of in the last chapter. Next in the order of antiquity are the lower-level gravels, Number 2, which we have now to describe; after which the alluvium, Number 3, found at higher levels, or about 80 and 100 feet above the river-plain, will remain to be considered. I have selected, as illustrating the old alluvium of the Somme occurring at levels slightly elevated above the present river, the sand and gravel-pits of Menchecourt, in the northwest suburbs of Abbeville, to which, as before stated, attention was first drawn by M. Boucher de Perthes, in his work on Celtic antiquities. Here, although in every adjoining pit some minor variations in the nature and thickness of the superimposed deposits may be seen, there is yet a general approach to uniformity in the series. The only stratum of which the relative age is somewhat doubtful, is the gravel marked a, underlying the peat, and resting on the Chalk. It is only known by borings, and some of it may be of the same age as Number 3; but I believe it to be for the most part of more modern origin, consisting of the wreck of all the older gravel, including Number 3, and formed during the last hollowing out and deepening of the valley immediately before the commencement of the growth of peat. The greater number of flint implements have been dug out of Number 3, often near the bottom, and twenty-five, thirty, or even more than thirty feet below the surface of Number 1. A geologist will perceive by a glance at the section that the valley of the Somme must have been excavated nearly to its present depth and width when the strata of Number 3 were thrown down, and that after the deposits Numbers 3, 2, and 1 had been formed in succession, the present valley was scooped out, patches only of Numbers 3 and 2 being left. For these deposits cannot originally have ended abruptly as they now do, but must have once been continuous farther towards the centre of the valley. [Illustration: Figure 16. Fluvio-Marine Strata] (FIGURE 16. SECTION OF FLUVIO-MARINE STRATA, CONTAINING FLINT IMPLEMENTS AND BONES OF EXTINCT MAMMALIA, AT MENCHECOURT, ABBEVILLE.* (* For detailed sections and maps of this district, see Prestwich, "Philosophical Transactions" 1860 page 277.) 1. Brown clay with angular flints, and occasionally Chalk rubble, unstratified, following the slope of the hill, probably of subaerial origin, of very varying thickness, from 2 to 5 feet and upwards. 2. Calcareous loam, buff-coloured, resembling loess, for the most part unstratified, in some places with slight traces of stratification, containing freshwater and land shells, with bones of elephants, etc.; thickness about 15 feet. 3. Alternations of beds of gravel, marl, and sand, with freshwater and land shells, and, in some of the lower sands, a mixture of marine shells; also bones of elephant, rhinoceros, etc., and flint implements; thickness about 12 feet. a. Gravel underlying peat, age undetermined. b. Layer of impervious clay, separating the gravel from the peat.) To begin with the oldest, Number 3, it is made up of a succession of beds, chiefly of freshwater origin, but occasionally a mixture of marine and fluviatile shells is observed in it, proving that the sea sometimes gained upon the river, whether at high tides or when the fresh water was less in quantity during the dry season, and sometimes perhaps when the land was slightly depressed in level. All these accidents might occur again and again at the mouth of any river, and give rise to alternations of fluviatile and marine strata, such as are seen at Menchecourt. In the lowest beds of gravel and sand in contact with the Chalk, flint hatchets, some perfect, others much rolled, have been found; and in a sandy bed in this position some workmen, whom I employed to sink a pit, found four flint knives. Above this sand and gravel occur beds of white and siliceous sand, containing shells of the genera Planorbis, Limnea, Paludina, Valvata, Cyclas, Cyrena, Helix, and others, all now natives of the same part of France, except Cyrena fluminalis (Figure 17), which no longer lives in Europe, but inhabits the Nile, and many parts of Asia, including Cashmere, where it abounds. No species of Cyrena is now met with in a living state in Europe. Mr. Prestwich first observed it fossil at Menchecourt, and it has since been found in two or three contiguous sand-pits, always in the fluvio-marine bed. [16] [Illustration: Figure 17. Cyrena fluminalis] (FIGURE 17. Cyrena fluminalis, O.F. Muller, sp.* (* For synonyms, see S. Woodward "Tibet Shells" "Proceedings of the Zoological Society" July 8, 1856.) a. Interior of left valve, from Gray's Thurrock, Essex. b. Hinge of the same magnified. c. Interior of right valve of a small specimen, from Shacklewell, London. d. Outer surface of right valve, from Erith, Kent.) TABLE 8/1. DATES OF SPECIFIC NAMES. COLUMN 1: SPECIES. COLUMN 2: DATE. LIVING: Tellina fluminalis, O.F. Muller: 1774. Venus fluminalis Euphratis, Chemnitz: 1782. Cyclas Euphratica, Lam.: 1806. Cyrena cor, Lam. (Nile): 1818. Cyrena consobrina, Caillaud (Nile): 1823. Cyrena Cashmiriensis, Desh.: Corbicuia fluminalis, Muhlfeldt.: 1811. FOSSIL: Cyrena trigonula, S. Woodward: 1834. Cyrena Gemmellarii, Philippi: 1836. Cyrena Duchastelii, Nyst: 1838. The following marine shells occur mixed with the freshwater species above enumerated:--Buccinum undatum, Littorina littorea, Nassa reticulata, Purpura lapillus, Tellina solidula, Cardium edule, and fragments of some others. Several of these I have myself collected entire, though in a state of great decomposition, lying in the white sand called "sable aigre" by the workmen. They are all littoral species now proper to the contiguous coast of France. Their occurrence in a fossil state associated with freshwater shells at Menchecourt had been noticed as long ago as 1836 by MM. Ravin and Baillon, before M. Boucher de Perthes commenced the researches which have since made the locality so celebrated.* (* D'Archiac, "Histoire des Progres" etc. volume 2 page 154.) The numbers since collected preclude all idea of their having been brought inland as eatable shells by the fabricators of the flint hatchets found at the bottom of the fluvio-marine sands. From the same beds, and in marls alternating with the sands, remains of the elephant, rhinoceros, and other mammalia have been exhumed. Above the fluvio-marine strata are those designated Number 2 in the section (Figure 16), which are almost devoid of stratification, and probably formed of mud or sediment thrown down by the waters of the river when they overflowed the ancient alluvial plain of that day. Some land shells, a few river shells, and bones of mammalia, some of them extinct, occur in Number 2. Its upper surface has been deeply furrowed and cut into by the action of water, at the time when the earthy matter of Number 1 was superimposed. The materials of this uppermost deposit are arranged as if they had been the result of land floods, taking place after the formations 2 and 3 had been raised, or had become exposed to denudation. The fluvio-marine strata and overlying loam of Menchecourt recur on the opposite or left bank of the alluvial plain of the Somme, at a distance of 2 or 3 miles. They are found at Mautort, among other places, and I obtained there the flint hatchet shown in Figure 9, of an oval form. It was extracted from gravel, above which were strata containing a mixture of marine and freshwater shells, precisely like those of Menchecourt. In the alluvium of all parts of the valley, both at high and low levels, rolled bones are sometimes met with in the gravel. Some of the flint tools in the gravel of Abbeville have their angles very perfect, others have been much triturated, as if in the bed of the main river or some of its tributaries. The mammalia most frequently cited as having been found in the deposits Numbers 2 and 3 at Menchecourt, are the following:-- Elephas primigenius. Rhinoceros tichorhinus. Equus fossilis, Owen. Bos primigenius. Cervus somonensis, Cuvier. C. tarandus priscus, Cuvier. Felis spelaea. Hyaena spelaea. The Ursus spelaeus has also been mentioned by some writers; but M. Lartet says he has sought in vain for it among the osteological treasures sent from Abbeville to Cuvier at Paris, and in other collections. The same palaeontologist, after a close scrutiny of the bones sent formerly to the Paris Museum from the valley of the Somme, observed that some of them bore the evident marks of an instrument, agreeing well with incisions such as a rude flint-saw would produce. Among other bones mentioned as having been thus artificially cut, are those of a Rhinoceros tichorhinus, and the antlers of Cervus somonensis.* (* "Quarterly Journal of the Geological Society" volume 16 1860 page 471.) The evidence obtained by naturalists that some of the extinct mammalia of Menchecourt really lived and died in this part of France, at the time of the embedding of the flint tools in fluviatile strata, is most satisfactory; and not the less so for having been put on record long before any suspicion was entertained that works of art would ever be detected in the same beds. Thus M. Baillon, writing in 1834 to M. Ravin, says: "They begin to meet with fossil bones at the depth of 10 or 12 feet in the Menchecourt sand-pits, but they find a much greater quantity at the depth of 18 and 20 feet. Some of them were evidently broken before they were embedded, others are rounded, having, without doubt, been rolled by running water. It is at the bottom of the sand-pits that the most entire bones occur. Here they lie without having undergone fracture or friction, and seem to have been articulated together at the time when they were covered up. I found in one place a whole hind limb of a rhinoceros, the bones of which were still in their true relative position. They must have been joined together by ligaments, and even surrounded by muscles at the time of their interment. The entire skeleton of the same species was lying at a short distance from the spot."* (* "Societe Roy. d'Emulation d'Abbeville" 1834 page 197.) If we suppose that the greater number of the flint implements occurring in the neighbourhood of Abbeville and Amiens were brought by river action into their present position, we can at once explain why so large a proportion of them are found at considerable depths from the surface, for they would naturally be buried in gravel and not in fine sediment, or what may be termed "inundation mud," such as Number 2 (Figure 16), a deposit from tranquil water, or where the stream had not sufficient force or velocity to sweep along Chalk flints, whether wrought or unwrought. Hence we have almost always to pass down through a mass of incumbent loam with land shells, or through fine sand with freshwater molluscs, before we get into the beds of gravel containing hatchets. Occasionally a weapon used as a projectile may have fallen into quiet water, or may have dropped from a canoe to the bottom of the river, or may have been floated by ice, as are some stones occasionally by the Thames in severe winters, and carried over the meadows bordering its banks; but such cases are exceptional, though helping to explain how isolated flint tools or pebbles and angular stones are now and then to be seen in the midst of the finest loams. The endless variety in the sections of the alluvium of the valley of the Somme, may be ascribed to the frequent silting up of the main stream and its tributaries during different stages of the excavation of the valley, probably also during changes in the level of the land. As a rule, when a river attacks and undermines one bank, it throws down gravel and sand on the opposite side of its channel, which is growing somewhere shallower, and is soon destined to be raised so high as to form an addition to the alluvial plain, and to be only occasionally inundated. In this way, after much encroachment on cliff or meadow at certain points, we find at the end of centuries that the width of the channel has not been enlarged, for the new made ground is raised after a time to the average height of the older alluvial tract. Sometimes an island is formed in midstream, the current flowing for a while on both sides of it, and at length scooping out a deeper channel on one side so as to leave the other to be gradually filled up during freshets and afterwards elevated by inundation mud, or "brick-earth." During the levelling up of these old channels, a flood sometimes cuts into and partially removes portions of the previously stratified matter, causing those repeated signs of furrowing and filling up of cavities, those memorials of doing and undoing, of which the tool-bearing sands and gravels of Abbeville and Amiens afford such reiterated illustrations, and of which a parallel is furnished by the ancient alluvium of the Thames valley, where similar bones of extinct mammalia and shells, including Cyrena fluminalis, are found. Professor Noeggerath, of Bonn, informs me that, about the year 1845, when the bed of the Rhine was deepened artificially by the blasting and removal of rock in the narrows at Bingerloch, not far from Bingen, several flint hatchets and an extraordinary number of iron weapons of the Roman period were brought up by the dredge from the bed of the great river. The decomposition of the iron had caused much of the gravel to be cemented together into a conglomerate. In such a case we have only to suppose the Rhine to deviate slightly from its course, changing its position, as it has often done in various parts of its plain in historical times, and then tools of the stone and iron periods would be found in gravel at the bottom with a great thickness of sand and overlying loam deposited above them. Changes in a river plain, such as those above alluded to, give rise frequently to ponds, swamps, and marshes, marking the course of old beds or branches of the river not yet filled up, and in these depressions shells proper both to running and stagnant water may be preserved, and quadrupeds may be mired. The latest and uppermost deposit of the series will be loam or brick-earth, with land and amphibious shells (Helix and Succinea), while below will follow strata containing freshwater shells, implying continuous submergence; and lowest of all in most sections will be the coarse gravel accumulated by a current of considerable strength and velocity. When the St. Katharine docks were excavated at London, and similar works executed on the banks of the Mersey, old ships were dug out, as I have elsewhere noticed,* showing how the Thames and Mersey have in modern times been shifting their channels. (* "Principles of Geology" 10th edition volume 2 page 547.) Recently, an old silted-up bed of the Thames has been discovered by boring at Shoeburyness at the mouth of the river opposite Sheerness, as I learn from Mr. Mylne. The old deserted branch is separated from the new or present channel of the Thames, by a mass of London Clay which has escaped denudation. The depth of the old branch, or the thickness of fluviatile strata with which it has been filled up, is 75 feet. The actual channel in the neighbourhood is now 60 feet deep, but there is probably 10 or 15 feet of stratified sand and gravel at the bottom; so that, should the river deviate again from its course, its present bed might be the receptacle of a fluvio-marine formation 75 feet thick, equal to the former one of Shoeburyness, and more considerable than that of Abbeville. It would consist both of freshwater and marine strata, as the salt water is carried by the tide far up above Sheerness; but in order that such deposits should resemble, in geological position, the Menchecourt beds, they must be raised 10 or 15 feet above their present level, and be partially eroded. Such erosion they would not fail to suffer during the process of upheaval, because the Thames would scour out its bed, and not alter its position relatively to the sea, while the land was gradually rising. Before the canal was made at Abbeville, the tide was perceptible in the Somme for some distance above that city. It would only require, therefore, a slight subsidence to allow the salt water to reach Menchecourt, as it did in the Pleistocene period. As a stratum containing exclusively land and freshwater shells usually underlies the fluvio-marine sands at Menchecourt, it seems that the river first prevailed there, after which the land subsided; and then there was an upheaval which raised the country to a greater height than that at which it now stands, after which there was a second sinking, indicated by the position of the peat, as already explained. All these changes happened since Man first inhabited this region. At several places in the environs of Abbeville there are fluviatile deposits at a higher level by 50 feet than the uppermost beds at Menchecourt, resting in like manner on the Chalk. One of these occurs in the suburbs of the city at Moulin Quignon, 100 feet above the Somme and on the same side of the valley as Menchecourt, and containing flint implements of the same antique type and the bones of elephants; but no marine shells have been found there, nor in any gravel or sand at higher elevations than the Menchecourt marine shells. It has been a matter of discussion among geologists whether the higher or the lower sands and gravels of the Somme valley are the more ancient. As a general rule, when there are alluvial formations of different ages in the same valley, those which occupy a more elevated position above the river plain are the oldest. In Auvergne and Velay, in Central France, where the bones of fossil quadrupeds occur at all heights above the present rivers from 10 to 1000 feet, we observe the terrestrial fauna to depart in character from that now living in proportion as we ascend to higher terraces and platforms. We pass from the lower alluvium, containing the mammoth, tichorhine rhinoceros, and reindeer, to various older groups of fossils, till, on a tableland 1000 feet high (near Le Puy, for example), the abrupt termination of which overlooks the present valley, we discover an old extinct river-bed covered by a current of ancient lava, showing where the lowest level was once situated. In that elevated alluvium the remains of a Tertiary mastodon and other quadrupeds of like antiquity are embedded. If the Menchecourt beds had been first formed, and the valley, after being nearly as deep and wide as it is now, had subsided, the sea must have advanced inland, causing small delta-like accumulations at successive heights, wherever the main river and its tributaries met the sea. Such a movement, especially if it were intermittent, and interrupted occasionally by long pauses, would very well account for the accumulation of stratified debris which we encounter at certain points in the valley, especially around Abbeville and Amiens. But we are precluded from adopting this theory by the entire absence of marine shells, and the presence of freshwater and land species, and mammalian bones, in considerable abundance, in the drift both of higher and lower levels above Abbeville. Had there been a total absence of all organic remains, we might have imagined the former presence of the sea, and the destruction of such remains might have been ascribed to carbonic acid or other decomposing causes; but the Pleistocene and implement-bearing strata can be shown by their fossils to be of fluviatile origin. FLINT IMPLEMENTS IN GRAVEL NEAR AMIENS. GRAVEL OF ST. ACHEUL. When we ascend the valley of the Somme, from Abbeville to Amiens, a distance of about 25 miles, we observe a repetition of all the same alluvial phenomena which we have seen exhibited at Menchecourt and its neighbourhood, with the single exception of the absence of marine shells and of Cyrena fluminalis. We find lower-level gravel, such as Number 2, Figure 7, and higher-level alluvium, such as Number 3, the latter rising to 100 feet above the plain, which at Amiens is about 50 feet above the level of the river at Abbeville. In both the upper and lower gravels, as Dr. Rigollot stated in 1854, flint tools and the bones of extinct animals, together with river shells and land shells of living species, abound. [Illustration: Figures 18, 19 and 20. Elephas] (FIGURE 18.* Elephas primigenius. Penultimate molar, lower jaw, right side, one-third of natural size, Pleistocene. Co-existed with Man.) (FIGURE 19.* Elephas antiquus, Falconer. Penultimate molar, lower jaw, right side, one-third of natural size, Pleistocene and Newer Pliocene. Co-existed with Man.) (FIGURE 20.* Elephas meridionalis, Nesti. Penultimate molar, lower jaw, right side, one-third of natural size, Newer Pliocene, Saint Prest, near Chartres, and Norwich Crag. Not yet proved to have coexisted with Man.) (* For Figure 20 I am indebted to M. Lartet, and Figure 18 will be found in his paper in "Bulletin de la Societe Geologique de France" March 1859. Figure 19 is from Falconer and Cautley "Fauna Sivalensis.") Immediately below Amiens, a great mass of stratified gravel, slightly elevated above the alluvial plain of the Somme, is seen at St. Roch, and half a mile farther down the valley at Montiers. Between these two places a small tributary stream, called the Celle, joins the Somme. In the gravel at Montiers, Mr. Prestwich and I found some flint knives, one of them flat on one side, but the other carefully worked, and exhibiting many fractures, clearly produced by blows skilfully applied. Some of these knives were taken from so low a level as to satisfy us that this great bed of gravel at Montiers, as well as that of the contiguous quarries of St. Roch, which seems to be a continuation of the same deposit, may be referred to the human period. Dr. Rigollot had already mentioned flint hatchets as obtained by him from St. Roch, but as none have been found there of late years, his statement was thought to require confirmation. The discovery, therefore, of these flint knives in gravel of the same age was interesting, especially as many tusks of a hippopotamus have been obtained from the gravel of St. Roch--some of these recently by Mr. Prestwich; while M. Garnier of Amiens has procured a fine elephant's molar from the same pits, which Dr. Falconer refers to Elephas antiquus, see Figure 19. Hence I infer that both these animals co-existed with Man. The alluvial formations of Montiers are very instructive in another point of view. If, leaving the lower gravel of that place, which is topped with loam or brick-earth (of which the upper portion is about 30 feet above the level of the Somme), we ascend the Chalk slope to the height of about 80 feet, another deposit of gravel and sand, with fluviatile shells in a perfect condition, occurs, indicating most clearly an ancient river-bed, the waters of which ran habitually at that higher level before the valley had been scooped out to its present depth. This superior deposit is on the same side of the Somme, and about as high, as the lowest part of the celebrated formation of St. Acheul, 2 or 3 miles distant, to which I shall now allude. The terrace of St. Acheul may be described as a gently sloping ledge of Chalk, covered with gravel, topped as usual with loam or fine sediment, the surface of the loam being 100 feet above the Somme, and about 150 above the sea. Many stone coffins of the Gallo-Roman period have been dug out of the upper portion of this alluvial mass. The trenches made for burying them sometimes penetrate to the depth of 8 or 9 feet from the surface, entering the upper part of Number 3 of the sections Figures 21 and 22. They prove that when the Romans were in Gaul they found this terrace in the same condition as it is now, or rather as it was before the removal of so much gravel, sand, clay, and loam, for repairing roads, and for making bricks and pottery. [Illustration: Figure 21. Section of Gravel Pit] (FIGURE 21. SECTION OF GRAVEL PIT CONTAINING FLINT IMPLEMENTS AT ST. ACHEUL, NEAR AMIENS, OBSERVED IN JULY 1860. 1. Vegetable soil and made ground, 2 to 3 feet thick. 2. Brown loam with some angular flints, in parts passing into ochreous gravel, filling up indentations on the surface of Number 3, 3 feet thick. 3. White siliceous sand with layers of chalky marl, and included fragments of Chalk, for the most part unstratified, 9 feet. 4. Flint-gravel, and whitish chalky sand, flints subangular, average size of fragments, 3 inches diameter, but with some large unbroken Chalk flints intermixed, cross stratification in parts. Bones of mammalia, grinder of elephant at b, and flint implement at c, 10 to 14 feet. 5. Chalk with flints. a. Part of elephant's molar, 11 feet from the surface. b. Entire molar of Elephas primigenius, 17 feet from the surface. c. Position of flint hatchet, 18 feet from the surface.) In the annexed section (Figure 21), which I observed during my last visit in 1860, it will be seen that a fragment of an elephant's tooth is noticed as having been dug out of unstratified sandy loam at the point a, 11 feet from the surface. This was found at the time of my visit; and at a lower point, at b, 18 feet from the surface, a large nearly entire and unrolled molar of the same species was obtained, which is now in my possession. It has been pronounced by Dr. Falconer to belong to Elephas primigenius. A stone hatchet of an oval form, like that represented at Figure 9, was discovered at the same time, about one foot lower down, at c, in densely compressed gravel. The surface of the fundamental Chalk is uneven in this pit, and slopes towards the valley-plain of the Somme. In a horizontal distance of 20 feet, I found a difference in vertical height of 7 feet. In the chalky sand, sometimes occurring in interstices between the separate fragments of flint, constituting the coarse gravel Number 4, entire as well as broken freshwater shells are often met with. To some it may appear enigmatical how such fragile objects could have escaped annihilation in a river-bed, when flint tools and much gravel were shoved along the bottom; but I have seen the dredging instrument employed in the Thames, above and below London Bridge, to deepen the river, and worked by steam power, scoop up gravel and sand from the bottom, and then pour the contents pell-mell into the boat, and still many specimens of Limnaea, Planorbis, Paludina, Cyclas, and other shells might be taken out uninjured from the gravel. It will be observed that the gravel Number 4 is obliquely stratified, and that its surface had undergone denudation before the white sandy loam Number 3 was superimposed. The materials of the gravel at d must have been cemented or frozen together into a somewhat coherent mass to allow the projecting ridge, d, to stand up 5 feet above the general surface, the sides being in some places perpendicular. In Number 3 we probably behold an example of a passage from river-silt to inundation mud. In some parts of it, land shells occur. It has been ascertained by MM. Buteux, Ravin, and other observers conversant with the geology of this part of France, that in none of the alluvial deposits, ancient or modern, are there any fragments of rocks foreign to the basin of the Somme--no erratics which could only be explained by supposing them to have been brought by ice, during a general submergence of the country, from some other hydrographical basin. But in some of the pits at St. Acheul there are seen in the beds Number 4, Figure 21, not only well-rounded Tertiary pebbles, but great blocks of hard sandstone, of the kind called in the south of England "greywethers," some of which are 3 or 4 feet and upwards in diameter. They are usually angular, and when spherical owe their shape generally to an original concretionary structure, and not to trituration in a river's bed. These large fragments of stone abound both in the higher and lower level gravels round Amiens and at the higher level at Abbeville. They have also been traced far up the valley above Amiens, wherever patches of the old alluvium occur. They have all been derived from the Tertiary strata which once covered the Chalk. Their dimensions are such that it is impossible to imagine a river like the present Somme, flowing through a flat country, with a gentle fall towards the sea, to have carried them for miles down its channel unless ice co-operated as a transporting power. Their angularity also favours the supposition of their having been floated by ice, or rendered so buoyant by it as to have escaped much of the wear and tear which blocks propelled along the bottom of a river channel would otherwise suffer. We must remember that the present mildness of the winters in Picardy and the northwest of Europe generally is exceptional in the northern hemisphere, and that large fragments of granite, sandstone, and limestone are now carried annually by ice down the Canadian rivers in latitudes farther south than Paris.* (* "Principles of Geology" 9th edition page 220.) [Illustration: Figure 22. Contorted Strata] (FIGURE 22. CONTORTED FLUVIATILE STRATA AT ST. ACHEUL (Prestwich, "Philosophical Transactions" 1861, page 299). 1. Surface soil. 2. Brown loam as in Figure 21, thickness, 6 feet. 3. White sand with bent and folded layers of marl, thickness, 6 feet. 4. Gravel, as in Figure 21, with bones of mammalia and flint implements. A. Graves filled with made ground and human bones. b and c. Seams of laminated marl often bent round upon themselves. d. Beds of gravel with sharp curves.) Another sign of ice agency, of which Mr. Prestwich has given a good illustration in one of his published sections, and which I myself observed in several pits at St. Acheul, deserves notice. It consists in flexures and contortions of the strata of sand, marl, and gravel (as seen at b, c, and d, Figure 22), which they have evidently undergone since their original deposition, and from which both the underlying Chalk and part of the overlying beds of sand Number 3 are usually exempt. In my former writings I have attributed this kind of derangement to two causes; first, the pressure of ice running aground on yielding banks of mud and sand; and, secondly, the melting of masses of ice and snow of unequal thickness, on which horizontal layers of mud, sand, and other fine and coarse materials had accumulated. The late Mr. Trimmer first pointed out in what manner the unequal failure of support caused by the liquefaction of underlying or intercalated snow and ice might give rise to such complicated foldings.* (* See chapter 12.) When "ice-jams" occur on the St. Lawrence and other Canadian rivers (latitude 46 degrees north), the sheets of ice, which become packed or forced under or over one another, assume in most cases a highly inclined and sometimes even a vertical position. They are often observed to be coated on one side with mud, sand, or gravel frozen on to them, derived from shallows in the river on which they rested when congelation first reached the bottom. As often as portions of these packs melt near the margin of the river, the layers of mud, sand, and gravel, which result from their liquefaction, cannot fail to assume a very abnormal arrangement--very perplexing to a geologist who should undertake to interpret them without having the ice-clue in his mind. Mr. Prestwich has suggested that ground-ice may have had its influence in modifying the ancient alluvium of the Somme.* (* Prestwich, Memoir read to Royal Society, April 1862.) It is certain that ice in this form plays an active part every winter in giving motion to stones and gravel in the beds of rivers in European Russia and Siberia. It appears that when in those countries the streams are reduced nearly to the freezing point, congelation begins frequently at the bottom; the reason being, according to Arago, that the current is slowest there, and the gravel and large stones, having parted with much of their heat by radiation, acquire a temperature below the average of the main body of the river. It is, therefore, when the water is clear, and the sky free from clouds, that ground ice forms most readily, and oftener on pebbly than on muddy bottoms. Fragments of such ice, rising occasionally to the surface, bring up with them gravel, and even large stones. Without dwelling longer on the various ways in which ice may affect the forms of stratification in drift, so as to cause bendings and foldings in which the underlying or over-lying strata do not participate, a subject to which I shall have occasion again to allude in the sequel, I will state in this place that such contortions, whether explicable or not, are very characteristic of glacial formations. They have also no necessary connection with the transportation of large blocks of stone, and they therefore afford, as Mr. Prestwich remarks, independent proof of ice-action in the Pleistocene gravel of the Somme. Let us, then, suppose that, at the time when flint hatchets were embedded in great numbers in the ancient gravel which now forms the terrace of St. Acheul, the main river and its tributaries were annually frozen over for several months in winter. In that case, the primitive people may, as Mr. Prestwich hints, have resembled in their mode of life those American Indians who now inhabit the country between Hudson's Bay and the Polar Sea. The habits of those Indians have been well described by Hearne, who spent some years among them. As often as deer and other game become scarce on the land, they betake themselves to fishing in the rivers; and for this purpose, and also to obtain water for drinking, they are in the constant practice of cutting round holes in the ice, a foot or more in diameter, through which they throw baited hooks or nets. Often they pitch their tent on the ice, and then cut such holes through it, using ice-chisels of metal when they can get copper or iron, but when not, employing tools of flint or hornstone. The great accumulation of gravel at St. Acheul has taken place in part of the valley where the tributary streams, the Noye and the Arve, now join the Somme. These tributaries, as well as the main river, must have been running at the height first of 100 feet, and afterwards at various lower levels above the present valley-plain, in those earlier times when the flint tools of the antique type were buried in successive river beds. I have said at various levels, because there are, here and there, patches of drift at heights intermediate between the higher and lower gravel, and also some deposits, showing that the river once flowed at elevations above as well as below the level of the platform of St. Acheul. As yet, however, no patch of gravel skirting the valley at heights exceeding 100 feet above the Somme has yielded flint tools or other signs of the former sojourn of Man in this region. Possibly, in the earlier geographical condition of this country, the confluence of tributaries with the Somme afforded inducements to a hunting and fishing tribe to settle there, and some of the same natural advantages may have caused the first inhabitants of Amiens and Abbeville to fix on the same sites for their dwellings. If the early hunting and fishing tribes frequented the same spots for hundreds or thousands of years in succession, the number of the stone implements lost in the bed of the river need not surprise us. Ice-chisels, flint hatchets, and spear-heads may have slipped accidentally through holes kept constantly open, and the recovery of a lost treasure once sunk in the bed of the ice-bound stream, inevitably swept away with gravel on the breaking up of the ice in the spring, would be hopeless. During a long winter, in a country affording abundance of flint, the manufacture of tools would be continually in progress; and, if so, thousands of chips and flakes would be purposely thrown into the ice-hole, besides a great number of implements having flaws, or rejected as too unskilfully made to be worth preserving. As to the fossil fauna of the drift, considered in relation to the climate, when, in 1859, I took a collection which I had made of all the more common species of land and freshwater shells from the Amiens and Abbeville drift, to my friend M. Deshayes at Paris, he declared them to be, without exception, the same as those now living in the basin of the Seine. This fact may seem at first sight to imply that the climate had not altered since the flint tools were fabricated; but it appears that all these species of molluscs now range as far north as Norway and Finland, and may therefore have flourished in the valley of the Somme when the river was frozen over annually in winter.* (* See Prestwich, Paper read to the Royal Society in 1862.) In regard to the accompanying mammalia, some of them, like the mammoth and tichorhine rhinoceros, may have been able to endure the rigours of a northern winter as well as the reindeer, which we find fossil in the same gravel. It is a more difficult point to determine whether the climate of the lower gravels (those of Menchecourt, for example) was more genial than that of the higher ones. Mr. Prestwich inclines to this opinion. None of those contortions of the strata above described have as yet been observed in the lower drift. It contains large blocks of Tertiary sandstone and grit, which may have required the aid of ice to convey them to their present sites; but as such blocks already abounded in the older and higher alluvium, they may simply be monuments of its destruction, having been let down successively to lower and lower levels without making much seaward progress. The Cyrena fluminalis of Menchecourt and the hippopotamus of St. Roch seem to be in favour of a less severe temperature in winter; but so many of the species of mammalia, as well as of the land and freshwater shells, are common to both formations, and our information respecting the entire fauna is still so imperfect, that it would be premature to pretend to settle this question in the present state of our knowledge. We must be content with the conclusion (and it is one of no small interest), that when Man first inhabited this part of Europe, at the time that the St. Acheul drift was formed, the climate as well as the physical geography of the country differed considerably from the state of things now established there. Among the elephant remains from St. Acheul, in M. Garnier's collection, Dr. Falconer recognised a molar of the Elephas antiquus, Figure 19, the same species which has been already mentioned as having been found in the lower-level gravels of St. Roch. This species, therefore, endured while important changes took place in the geographical condition of the valley of the Somme. Assuming the lower-level gravel to be the newer, it follows that the Elephas antiquus and the hippopotamus of St. Roch continued to flourish long after the introduction of the mammoth, a well characterised tooth of which, as I before stated, was found at St. Acheul at the time of my visit in 1860. As flint hatchets and knives have been discovered in the alluvial deposits both at high and low levels, we may safely affirm that Man was as old an inhabitant of this region as were any of the fossil quadrupeds above enumerated, a conclusion which is independent of any difference of opinion as to the relative age of the higher and lower gravels. The disappearance of many large pachyderms and beasts of prey from Europe has often been attributed to the intervention of Man, and no doubt he played his part in hastening the era of their extinction; but there is good reason for suspecting that other causes co-operated to the same end. No naturalist would for a moment suppose that the extermination of the Cyrena fluminalis throughout the whole of Europe--a species which co-existed with our race in the valley of the Somme, and which was very abundant in the waters of the Thames at the time when the elephant, rhinoceros, and hippopotamus flourished on its banks--was accelerated by human agency. The great modification in climate and in other conditions of existence which affected this aquatic mollusc, may have mainly contributed to the gradual dying out of many of the large mammalia. We have already seen that the peat of the valley of the Somme is a formation which, in all likelihood, took thousands of years for its growth. But no change of a marked character has occurred in the mammalian fauna since it began to accumulate. The contrast of the fauna of the ancient alluvium, whether at high or low levels, with the fauna of the oldest peat is almost as great as its contrast with the existing fauna, the memorials of Man being common to the whole series; hence we may infer that the interval of time which separated the era of the large extinct mammalia from that of the earliest peat, was of far longer duration than that of the entire growth of the peat. Yet we by no means need the evidence of the ancient fossil fauna to establish the antiquity of Man in this part of France. The mere volume of the drift at various heights would alone suffice to demonstrate a vast lapse of time during which such heaps of shingle, derived both from the Eocene and the Cretaceous rocks, were thrown down in a succession of river-channels. We observe thousands of rounded and half-rounded flints, and a vast number of angular ones, with rounded pieces of white Chalk of various sizes, testifying to a prodigious amount of mechanical action, accompanying the repeated widening and deepening of the valley, before it became the receptacle of peat; and the position of many of the flint tools leaves no doubt in the mind of the geologist that their fabrication preceded all this reiterated denudation. ON THE ABSENCE OF HUMAN BONES IN THE ALLUVIUM OF THE SOMME. It is naturally a matter of no small surprise that, after we have collected many hundred flint implements (including knives, many thousands), not a single human bone has yet been met with in the old alluvial sand and gravel of the Somme. This dearth of the mortal remains of our species holds true equally, as yet, in all other parts of Europe where the tool-bearing drift of the Pleistocene period has been investigated in valley deposits. Yet in these same formations there is no want of bones of mammalia belonging to extinct and living species. In the course of the last quarter of a century, thousands of them have been submitted to the examination of skilful osteologists, and they have been unable to detect among them one fragment of a human skeleton, not even a tooth. Yet Cuvier pointed out long ago, that the bones of Man found buried in ancient battle-fields were not more decayed than those of horses interred in the same graves. We have seen that in the Liege caverns, the skulls, jaws, and teeth, with other bones of the human race, were preserved in the same condition as those of the cave-bear, tiger, and mammoth. That ere long, now that curiosity has been so much excited on this subject, some human remains will be detected in the older alluvium of European valleys, I confidently expect. In the meantime, the absence of all vestige of the bones which belonged to that population by which so many weapons were designed and executed, affords a most striking and instructive lesson in regard to the value of negative evidence, when adduced in proof of the non-existence of certain classes of terrestrial animals at given periods of the past. It is a new and emphatic illustration of the extreme imperfection of the geological record, of which even they who are constantly working in the field cannot easily form a just conception. We must not forget that Dr. Schmerling, after finding extinct mammalia and FLINT TOOLS in forty-two Belgian caverns, was only rewarded by the discovery of human bones in three or four of those rich repositories of osseous remains. In like manner, it was not till the year 1855 that the first skull of the musk ox (Bubalus moschatus) was detected in the fossiliferous gravel of the Thames, and not till 1860, as will be seen in the next chapter, that the same quadruped was proved to have co-existed in France with the mammoth. The same theory which will explain the comparative rarity of such species would no doubt account for the still greater scarcity of human bones, as well as for our general ignorance of the Pleistocene terrestrial fauna, with the exception of that part of it which is revealed to us by cavern researches. In valley drift we meet commonly with the bones of quadrupeds which graze on plains bordering rivers. Carnivorous beasts, attracted to the same ground in search of their prey, sometimes leave their remains in the same deposits, but more rarely. The whole assemblage of fossil quadrupeds at present obtained from the alluvium of Picardy is obviously a mere fraction of the entire fauna which flourished contemporaneously with the primitive people by whom the flint hatchets were made. Instead of its being part of the plan of nature to store up enduring records of a large number of the individual plants and animals which have lived on the surface, it seems to be her chief care to provide the means of disencumbering the habitable areas lying above and below the waters of those myriads of solid skeletons of animals, and those massive trunks of trees, which would otherwise soon choke up every river, and fill every valley. To prevent this inconvenience she employs the heat and moisture of the sun and atmosphere, the dissolving power of carbonic and other acids, the grinding teeth and gastric juices of quadrupeds, birds, reptiles, and fish, and the agency of many of the invertebrata. We are all familiar with the efficacy of these and other causes on the land; and as to the bottoms of seas, we have only to read the published reports of Mr. MacAndrew, the late Edward Forbes, and other experienced dredgers, who, while they failed utterly in drawing up from the deep a single human bone, declared that they scarcely ever met with a work of art even after counting tens of thousands of shells and zoophytes, collected on a coast line of several hundred miles in extent, where they often approached within less than half a mile of a land peopled by millions of human beings. LAKE OF HAARLEM. It is not many years since the Government of Holland resolved to lay dry that great sheet of water formerly called the Lake of Haarlem, extending over 45,000 acres. They succeeded, in 1853, in turning it into dry land, by means of powerful pumps constantly worked by steam, which raised the water and discharged it into a canal running for 20 or 30 miles round the newly-gained land. This land was depressed 13 feet beneath the mean level of the ocean. I travelled, in 1859, over part of the bed of this old lake, and found it already converted into arable land, and peopled by an agricultural population of 5000 souls. Mr. Staring, who had been for some years employed by the Dutch Government in constructing a geological map of Holland, was my companion and guide. He informed me that he and his associates had searched in vain for human bones in the deposits which had constituted for three centuries the bed of the great lake. There had been many a shipwreck, and many a naval fight in those waters, and hundreds of Dutch and Spanish soldiers and sailors had met there with a watery grave. The population which lived on the borders of this ancient sheet of water numbered between thirty and forty thousand souls. In digging the great canal, a fine section had been laid open, about 30 miles long, of the deposits which formed the ancient bottom of the lake. Trenches, also, innumerable, several feet deep, had been freshly dug on all the farms, and their united length must have amounted to thousands of miles. In some of the sandy soil recently thrown out of the trenches, I observed specimens of freshwater and brackish-water shells, such as Unio and Dreissena, of living species; and in clay brought up from below the sand, shells of Tellina, Lutraria, and Cardium, all of species now inhabiting the adjoining sea. As the Dreissena is believed by conchologists to have been introduced into Western Europe in very modern times, brought with foreign timber in the holds of vessels from the rivers flowing into the Black Sea, the layer of sand containing it in the Haarlem lake is probably not more than a hundred years old. One or two wrecked Spanish vessels, and arms of the same period, have rewarded the antiquaries who had been watching the draining operations in the hope of a richer harvest, and who were not a little disappointed at the result. In a peaty tract on the margin of one part of the lake a few coins were dug up; but if history had been silent, and if there had been a controversy whether Man was already a denizen of this planet at the time when the area of the Haarlem lake was under water, the archaeologist, in order to answer this question, must have appealed, as in the case of the valley of the Somme, not to fossil bones, but to works of art embedded in the superficial strata. Mr. Staring, in his valuable memoir on the "Geological Map of Holland," has attributed the general scarcity of human bones in Dutch peat, notwithstanding the many works of art preserved in it, to the power of the humic and sulphuric acids to dissolve bones, the peat in question being plentifully impregnated with such acids. His theory may be correct, but it is not applicable to the gravel of the valley of the Somme, in which the bones of fossil mammalia are frequent, nor to the uppermost freshwater strata forming the bottom of a large part of the Haarlem Lake, in which it is not pretended that such acids occur. The primitive inhabitants of the valley of the Somme may have been too wary and sagacious to be often surprised and drowned by floods, which swept away many an incautious elephant or rhinoceros, horse and ox. But even if those rude hunters had cherished a superstitious veneration for the Somme, and had regarded it as a sacred river (as the modern Hindoos revere the Ganges), and had been in the habit of committing the bodies of their dead or dying to its waters--even had such funeral rites prevailed, it by no means follows that the bones of many individuals would have been preserved to our time. A corpse cast into the stream first sinks, and must then be almost immediately overspread with sediment of a certain weight, or it will rise again when distended with gases, and float perhaps to the sea before it sinks again. It may then be attacked by fish of marine species, some of which are capable of digesting bones. If, before being carried into the sea and devoured, it is enveloped with fluviatile mud and sand, the next flood, if it lie in mid-channel, may tear it out again, scatter all the bones, roll some of them into pebbles, and leave others exposed to destroying agencies; and this may be repeated annually, till all vestiges of the skeleton may disappear. On the other hand, a bone washed through a rent into a subterranean cavity, even though a rarer contingency, may have a greater chance of escaping destruction, especially if there be stalactite dropping from the roof of the cave or walls of a rent, and if the cave be not constantly traversed by too strong a current of engulfed water. CHAPTER 9. -- WORKS OF ART IN PLEISTOCENE ALLUVIUM OF FRANCE AND ENGLAND. Flint Implements in ancient Alluvium of the Basin of the Seine. Bones of Man and of extinct Mammalia in the Cave of Arcy. Extinct Mammalia in the Valley of the Oise. Flint Implement in Gravel of same Valley. Works of Art in Pleistocene Drift in Valley of the Thames. Musk Ox. Meeting of northern and southern Fauna. Migrations of Quadrupeds. Mammals of Mongolia. Chronological Relation of the older Alluvium of the Thames to the Glacial Drift. Flint Implements of Pleistocene Period in Surrey, Middlesex, Kent, Bedfordshire, and Suffolk. FLINT IMPLEMENTS IN PLEISTOCENE ALLUVIUM IN THE BASIN OF THE SEINE. In the ancient alluvium of the valleys of the Seine and its principal tributaries, the same assemblage of fossil animals, which has been alluded to in the last chapter as characterising the gravel of Picardy, has long been known; but it was not till the year 1860, and when diligent search had been expressly made for them, that flint implements of the Amiens type were discovered in this part of France. In the neighbourhood of Paris deposits of drift occur answering both to those of the higher and lower levels of the basin of the Somme before described.* (* Prestwich, "Proceedings of the Royal Society" 1862.) In both are found, mingled with the wreck of the Tertiary and Cretaceous rocks of the vicinity, a large quantity of granitic sand and pebbles, and occasionally large blocks of granite, from a few inches to a foot or more in diameter. These blocks are peculiarly abundant in the lower drift commonly called the "diluvium gris." The granitic materials are traceable to a chain of hills called the Morvan, where the head waters of the Yonne take their rise, 150 miles to the south-south-east of Paris. It was in this lowest gravel that M. H.T. Gosse, of Geneva, found, in April 1860, in the suburbs of Paris, at La Motte Piquet, on the left bank of the Seine, one or two well-formed flint implements of the Amiens type, accompanied by a great number of ruder tools or attempts at tools. I visited the spot in 1861 with M. Hebert, and saw the stratum from which the worked flints had been extracted, 20 feet below the surface, and near the bottom of the "grey diluvium," a bed of gravel from which I have myself, in and near Paris, frequently collected the bones of the elephant, horse, and other mammalia. More recently, M. Lartet has discovered at Clichy, in the environs of Paris, in the same lower gravel, a well-shaped flint implement of the Amiens type, together with remains both of Elephas primigenius and E. antiquus. No tools have yet been met with in any of the gravels occurring at the higher levels of the valley of the Seine; but no importance can be attached to this negative fact, as so little search has yet been made for them. Mr. Prestwich has observed contortions indicative of ice-action, of the same kind as those near Amiens, in the higher-level drift of Charonne, near Paris; but as yet no similar derangement has been seen in the lower gravels--a fact, so far as it goes, in unison with the phenomena observed in Picardy. In the cavern of Arcy-sur-Yonne a series of deposits have lately been investigated by the Marquis de Vibraye, who discovered human bones in the lowest of them, mixed with remains of quadrupeds of extinct and recent species. This cavern occurs in Jurassic limestone, at a slight elevation above the Cure, a small tributary of the Yonne, which last joins the Seine near Fontainebleau about 40 miles south of Paris. The lowest formation in the cavern resembles the "diluvium gris" of Paris, being composed of granitic materials, and like it derived chiefly from the waste of the crystalline rocks of the Morvan. In it have been found the two branches of a human lower jaw with teeth well-preserved, and the bones of the Elephas primigenius, Rhinoceros tichorhinus, Ursus spelaeus, Hyaena spelaea, and Cervus tarandus, all specifically determined by M. Lartet. I have been shown this collection of fossils by M. de Vibraye, and remarked that the human and other remains were in the same condition and of the same colour. Above the grey gravel is a bed of red alluvium, made up of fragments of Jurassic limestone, in a red argillaceous matrix, in which were embedded several flint knives, with bones of the reindeer and horse, but no extinct mammalia. Over this, in a higher bed of alluvium, were several polished hatchets of the more modern type called "celts," and above all loam or cave-mud, in which were Gallo-Roman antiquities.* (* "Bulletin de la Societe Geologique de France" 1860.) The French geologists have made as yet too little progress in identifying the age of the successive deposits of ancient alluvium of various parts of the basin of the Seine, to enable us to speculate with confidence as to the coincidence in date of the granitic gravel with human bones of the Grotte d'Arcy and the stone-hatchets buried in "grey diluvium" of La Motte Piquet, before mentioned; but as the associated extinct mammalia are of the same species in both localities, I feel strongly inclined to believe that the stone hatchets found by M. Gosse at Paris, and the human bones discovered by M. de Vibraye, may be referable to the same period. VALLEY OF THE OISE. A flint hatchet, of the old Abbeville and Amiens type, was found lately by M. Peigne Delacourt at Precy, near Creil, on the Oise, in gravel, resembling, in its geological position, the lower-level gravels of Montiers, near Amiens, already described. I visited these extensive gravel-pits in 1861, in company with Mr. Prestwich; but we remained there too short a time to entitle us to expect to find a flint implement, even if they had been as abundant as at St. Acheul. In 1859, I examined, in a higher part of the same valley of the Oise, near Chauny and Noyon, some fine railway cuttings, which passed continuously through alluvium of the Pleistocene period for half a mile. All this alluvium was evidently of fluviatile origin, for, in the interstices between the pebbles, the Ancylus fluviatilis and other freshwater shells were abundant. My companion, the Abbe E. Lambert, had collected from the gravel a great many fossil bones, among which M. Lartet has recognised both Elephas primigenius and E. antiquus, besides a species of hippopotamus (H. major?), also the reindeer, horse, and the musk ox (Bubalus moschatus). The latter seems never to have been seen before in the old alluvium of France.* (* Lartet, "Annales des Sciences Naturelles Zoologiques" tome 15 page 224.) Over the gravel above mentioned, near Chauny, are seen dense masses of loam like the loess of the Rhine, containing shells of the genera Helix and Succinea. We may suppose that the gravel containing the flint hatchet at Precy is of the same age as that of Chauny, with which it is continuous, and that both of them are coeval with the tool-bearing beds of Amiens, for the basins of the Oise and the Somme are only separated by a narrow water-shed, and the same fossil quadrupeds occur in both. The alluvium of the Seine and its tributaries, like that of the Somme, contains no fragments of rocks brought from any other hydrographical basin; yet the shape of the land, or fall of the river, or the climate, or all these conditions, must have been very different when the grey alluvium in which the flint tools occur at Paris was formed. The great size of some of the blocks of granite, and the distance which they have travelled, imply a power in the river which it no longer possesses. We can hardly doubt that river-ice once played a much more active part than now in the transportation of such blocks, one of which may be seen in the Museum of the Ecole des Mines at Paris, 3 or 4 feet in diameter. PLEISTOCENE ALLUVIUM OF ENGLAND, CONTAINING WORKS OF ART. In the ancient alluvium of the basin of the Thames, at moderate heights above the main river and its tributaries, we find fossil bones of the same species of extinct and living mammalia, accompanied by recent species of land and freshwater shells, as we have shown to be characteristic of the basins of the Somme and the Seine. We can scarcely therefore doubt that these quadrupeds, during some part of the Pleistocene period, ranged freely from the continent of Europe to England, at a time when there was an uninterrupted communication by land between the two countries. The reader will not therefore be surprised to learn that flint implements of the same antique type as those of the valley of the Somme have been detected in British alluvium. The most marked feature of this alluvium in the Thames valley is that great bed of ochreous gravel, composed chiefly of broken and slightly worn Chalk flints, on which a great part of London is built. It extends from above Maidenhead through the metropolis to the sea, a distance from west to east of 50 miles, having a width varying from 2 to 9 miles. Its thickness ranges commonly from 5 to 15 feet.* (* Prestwich, "Quarterly Journal of the Geological Society" volume 12 1856 page 131.) Interstratified with this gravel, in many places, are beds of sand, loam, and clay, the whole containing occasionally remains of the mammoth and other extinct quadrupeds. Fine sections have been exposed to view, at different periods, at Brentford and Kew Bridge, others in London itself, and below it at Erith in Kent, on the right bank of the Thames, and at Ilford and Gray's Thurrock in Essex, on the left bank. The united thickness of the beds of sand, gravel, and loam amounts sometimes to 40 or even 60 feet. They are for the most part elevated above, but in some cases they descend below, the present level of the overflowed plain of the Thames. If the reader will refer to the section of the Pleistocene sands and gravels of Menchecourt, near Abbeville, given at page 96, he will perfectly understand the relations of the ancient Thames alluvium to the modern channel and plain of the river, and their relation, on the other hand, to the boundary formations of older date, whether Tertiary or Cretaceous. So far as they are known, the fossil mollusca and mammalia of the two districts also agree very closely, the Cyrena fluminalis being common to both, and being the only extra-European shell, this and all the species of testacea being Recent. Of this agreement with the living fauna there is a fine illustration in Essex; for the determination of which we are indebted to the late Mr. John Brown, F.G.S., who collected at Copford, in Essex, from a deposit containing bones of the mammoth, a large bear (probably Ursus spelaeus), a beaver, stag, and aurochs, no less than sixty-nine species of land and freshwater shells. Forty-eight of these were terrestrial, and two of them, Helix incarnata and H. ruderata, no longer inhabit the British Isles, but are still living on the continent, ruderata in high northern latitudes.* (* "Quarterly Journal of the Geological Society" volume 8 1852 page 190. Mr. Brown calls them extinct species, which may mislead some readers, but he merely meant extinct in England. See also Jeffreys, "Brit. Conch." page 174.) The Cyrena fluminalis and the Unio littoralis, to which last I shall presently allude, were not among the number. I long ago suggested the hypothesis, that in the basin of the Thames there are indications of a meeting in the Pleistocene period of a northern and southern fauna. To the northern group may have belonged the mammoth (Elephas primigenius) and the Rhinoceros tichorhinus, both of which Pallas found in Siberia, preserved with their flesh in the ice. With these are occasionally associated the reindeer. In 1855 the skull of the musk ox (Bubalus moschatus) was also found in the ochreous gravel of Maidenhead, by the Reverend C. Kingsley and Mr. Lubbock; the identification of this fossil with the living species being made by Professor Owen. A second fossil skull of the same arctic animal was afterwards found by Mr. Lubbock near Bromley, in the valley of a small tributary of the Thames; and two other skulls, those of a bull and a cow were dug up near Bath Easton from the gravel of the valley of the Avon by Mr. Charles Moore. Professor Owen has truly said, that "as this quadruped has a constitution fitting it at present to inhabit the high northern regions of America, we can hardly doubt that its former companions, the warmly-clad mammoth and the two-horned woolly rhinoceros (R. tichorhinus), were in like manner capable of supporting life in a cold climate."* (* "Quarterly Journal of the Geological Society" volume 12 1856 page 124.) I have already alluded to the recent discovery of this same ox near Chauny, in the valley of the Oise, in France; and in 1856 I found a skull of it preserved in the museum at Berlin, which Professor Quenstedt, the curator, had correctly named so long ago as 1836, when the fossil was dug out of drift, in the hill called the Kreuzberg, in the southern suburbs of that city. By an account published at the time, we find that the mammalia which accompanied the musk ox were the mammoth and tichorhine rhinoceros, with the horse and ox;* but I can find no record of the occurrence of a hippopotamus, nor of Elephas antiquus or Rhinoceros leptorhinus, in the drift of the north of Germany, bordering the Baltic. (* "Leonhard and Bronn's Jahrbuch" 1836 page 215.) On the other hand, in another locality in the same drift of North Germany, Dr. Hensel, of Berlin, detected, near Quedlinburg, the Norwegian Lemming (Myodes lemmus), and another species of the same family called by Pallas Myodes torquatus (by Hensel, Misothermus torquatus)--a still more arctic quadruped, found by Parry in latitude 82 degrees, and which never strays farther south than the northern borders of the woody region. Professor Beyrich also informs me that the remains of the Rhinoceros tichorhinus were obtained at the same place.* (* "Zeitschrift der Deutschen Geologischen Gesellschaft" volume 7 1855 page 497 etc.) As an example of what may possibly have constituted a more southern fauna in the valley of the Thames, I may allude to the fossil remains found in the fluviatile alluvium of Gray's Thurrock, in Essex, situated on the left bank of the river, 21 miles below London. The strata of brick-earth, loam, and gravel exposed to view in artificial excavations in that spot, are precisely such as would be formed by the silting up of an old river channel. Among the mammalia are Elephas antiquus, Rhinoceros leptorhinus (R. megarhinus, Christol), Hippopotamus major, species of horse, bear, ox, stag, etc., and, among the accompanying shells, Cyrena fluminalis, which is extremely abundant, instead of being scarce, as at Abbeville. It is associated with Unio littoralis also in great numbers and with both valves united. This conspicuous freshwater mussel is no longer an inhabitant of the British Isles, but still lives in the Seine, and is still more abundant in the Loire. Another freshwater univalve (Paludina marginata, Michaud), not British, but common in the south of France, likewise occurs, and a peculiar variety of Cyclas amnica, which by some naturalists has been regarded as a distinct species. With these, moreover, is found a peculiar variety of Valvata piscinalis. If we consult Dr. Von Schrenck's account of the living mammalia of Mongolia, lying between latitude 45 and 55 degrees north, we learn that, in that part of North-Eastern Asia recently annexed to the Russian empire, no less than thirty-four out of fifty-eight living quadrupeds are identical with European species, while some of those which do not extend their range to Europe are arctic, others tropical forms. The Bengal tiger ranges northwards occasionally to latitude 52 degrees north, where he chiefly subsists on the flesh of the reindeer, and the same tiger abounds in latitude 48 degrees, to which the small tailless hare or pika, a polar resident, sometimes wanders southwards.* (* Mammalia of Amoorland, "Natural History Review" volume 1 1861 page 12.) We may readily conceive that the countries now drained by the Thames, the Somme, and the Seine, were, in the Pleistocene period, on the borders of two distinct zoological provinces, one lying to the north, the other to the south, in which case many species belonging to each fauna endowed with migratory habits, like the living musk-ox or the Bengal tiger, may have been ready to take advantage of any, even the slightest, change in their favour to invade the neighbouring province, whether in the summer or winter months, or permanently for a series of years, or centuries. The Elephas antiquus and its associated Rhinoceros leptorhinus may have preceded the mammoth and tichorhine rhinoceros in the valley of the Thames, or both may have alternately prevailed in the same area in the Pleistocene period. In attempting to settle the chronology of fluviatile deposits, it is almost equally difficult to avail ourselves of the evidence of organic remains and of the superposition of the strata, for we may find two old river-beds on the same level in juxtaposition, one of them perhaps many thousands of years posterior in date to the other. I have seen an example of this at Ilford, where the Thames, or a tributary stream, has at some former period cut through sands containing Cyrena fluminalis, and again filled up the channel with argillaceous matter, evidently derived from the waste of the Tertiary London Clay. Such shiftings of the site of the main channel of the river, the frequent removal of gravel and sand previously deposited, and the throwing down of new alluvium, the flooding of tributaries, the rising and sinking of the land, fluctuations in the cold and heat of the climate--all these changes seem to have given rise to that complexity in the fluviatile deposits of the Thames, which accounts for the small progress we have hitherto made in determining their order of succession, and that of the imbedded groups of quadrupeds. It may happen, as at Brentford and Ilford, that sand-pits in two adjoining fields may each contain distinct species of elephant and rhinoceros; and the fossil remains in both cases may occur at the same depth from the surface, yet may be severally referable to different parts of the Pleistocene epoch, separated by thousands of years. The relation of the glacial period to alluvial deposits, such as that of Gray's Thurrock, where the Cyrena fluminalis, Unio littoralis, and the hippopotamus seem rather to imply a warmer climate, has been a matter of long and animated discussion. Patches of the northern drift, at elevations of about 200 feet above the Thames, occur in the neighbourhood of London, as at Muswell Hill, near Highgate. In this drift, blocks of granite, syenite, greenstone, Coal-measure sandstone with its fossils, and other Palaeozoic rocks, and the wreck of Chalk and Oolite, occur confusedly mixed together. The same glacial formation is also found capping some of the Essex hills farther to the east, and extending some way down their southern slopes towards the valley of the Thames. Although no fragments washed out of these older and upland drifts have been found in the gravel of the Thames containing elephants' bones, it is fair to presume, as Mr. Prestwich has contended,* that the glacial formation is the older of the two. (* Prestwich, "Quarterly Journal of the Geological Society" volume 11 1855 page 110; ibid. volume 12 1856 page 133; ibid. volume 17 1861 page 446.) In short, we must suppose that the basin of the Thames and all its fluviatile deposits are post-glacial, in the modified sense of that term; i.e. that they were subsequent to the drift of the central and northern counties. Having offered these general remarks on the alluvium of the Thames, I may now say something of the implements hitherto discovered in it. In the British Museum there is a flint weapon of the spear-headed form, such as is represented in Figure 8, which we are told was found with an elephant's tooth at Black Mary's, near Gray's Inn Lane, London. In a letter dated 1715, printed in Herne's edition of "Leland's Collectanea," volume 1 page 73, it is stated to have been found in the presence of Mr. Conyers, with the skeleton of an elephant.* (* Evans, "Archaeologia" 1860.) So many bones of the elephant, rhinoceros, and hippopotamus have been found in the gravel on which London stands, that there is no reason to doubt the statement as handed down to us. Fossil remains of all these three genera have been dug up on the site of Waterloo Place, St. James's Square, Charing Cross, the London Docks, Limehouse, Bethnal Green, and other places within the memory of persons now living. In the gravel and sand of Shacklewell, in the north-east district of London, I have myself collected specimens of the Cyrena fluminalis in great numbers (see Figure 17 c), with the bones of deer and other mammalia. In the alluvium also of the Wey, near Guildford, in a place called Pease Marsh, a wedge-shaped flint implement, resembling one brought from St. Acheul by Mr. Prestwich, and compared by some antiquaries to a sling-stone, was obtained in 1836 by Mr. Whitburn, 4 feet deep in sand and gravel, in which the teeth and tusks of elephants had been found. The Wey flows through the gorge of the North Downs at Guildford to join the Thames. Mr. Austen has shown that this drift is so ancient that one part of it had been disturbed and tilted before another part was thrown down.* (* "Quarterly Journal of the Geological Society" volume 7 1851 page 278.) Among other places where flint tools of the antique type have been met with in the course of the last three years, I may mention one of an oval form found by Mr. Whitaker in the valley of the Darent, in Kent, and another which Mr. Evans found lying on the shore at Swalecliff, near Whitstable, in the same county, where Mr. Prestwich had previously described a freshwater deposit, resting on the London Clay, and consisting chiefly of gravel, in which an elephant's tooth and the bones of a bear were embedded. The flint implement was deeply discoloured and of a peculiar bright light-brown colour, similar to that of the old fluviatile gravel in the cliff. Another flint implement was found in 1860 by Mr. T. Leech, at the foot of the cliff between Herne Bay and the Reculvers, and on further search five other specimens of the spear-head pattern so common at Amiens. Messrs. Prestwich and Evans have since found three other similar tools on the beach, at the base of the same wasting cliff, which consists of sandy Eocene strata, covered by a gravelly deposit of freshwater origin, about 50 feet above the sea-level, from which the flint weapons must have been derived. Such old alluvial deposits now capping the cliffs of Kent seem to have been the river-beds of tributaries of the Thames before the sea encroached to its present position and widened its estuary. On following up one of these freshwater deposits westward of the Reculvers, Mr. Prestwich found in it, at Chislet, near Grove Ferry, the Cyrena fluminalis among other shells. The changes which have taken place in the physical geography of this part of England during, or since, the Pleistocene period, have consisted partly of such encroachments of the sea on the coast as are now going on, and partly of a general subsidence of the land. Among the signs of the latter movement may be mentioned a freshwater formation at Faversham, below the level of the sea. The gravel there contains exclusively land and fluviatile shells of the same species as those of other localities of the Pleistocene alluvium before mentioned, and must have been formed when the river was at a higher level and when it extended farther east. At that era it was probably a tributary of the Rhine, as represented by Mr. Trimmer in his ideal restoration of the geography of the olden time.* (* "Quarterly Journal of the Geological Society" volume 9 1853 Plate 8 Number 4.) For England was then united to the continent, and what is now the North Sea was land. It is well known that in many places, especially near the coast of Holland, elephants' tusks and other bones are often dredged up from the bed of that shallow sea, and the reader will see in the map given in Chapter 13 how vast would be the conversion of sea into land by an upheaval of 600 feet. Vertical movements of much less than half that amount would account for the annexation of England to the continent, and the extension of the Thames and its valley far to the north-east, and the flowing of rivers from the easternmost parts of Kent and Essex into the Thames, instead of emptying themselves into its estuary. More than a dozen flint weapons of the Amiens type have already been found in the basin of the Thames; but the geological position of no one of them has as yet been ascertained with the same accuracy as that of many of the tools dug up in the valley of the Somme. FLINT IMPLEMENTS OF THE VALLEY OF THE OUSE, NEAR BEDFORD. The ancient fluviatile gravel of the valley of the Ouse, around Bedford, has been noted for the last thirty years for yielding to collectors a rich harvest of the bones of extinct mammalia. By observations made in 1854 and 1858, Mr. Prestwich had ascertained that the valley was bounded on both sides by Oolitic strata, capped by boulder clay, and that the gravel Number 3, Figure 23, contained bones of the elephant, rhinoceros, hippopotamus, ox, horse, and deer, which animals he therefore inferred must have been posterior in date to the boulder clay, through which, as well as the subjacent Oolite, the valley had been excavated. Mr. Evans had found in the same gravel many land and freshwater shells, and these discoveries induced Mr. James Wyatt, of Bedford, to pay two visits to St. Acheul in order to compare the implement-bearing gravels of the Somme with the drift of the valley of the Ouse. After his return he resolved to watch carefully the excavation of the gravel-pits at Biddenham, 2 miles west-north-west of Bedford, in the hope of finding there similar works of art. With this view he paid almost daily visits for months in succession to those pits, and was at last rewarded by the discovery of two well-formed implements, one of the spear-head and the other of the oval shape, perfect counterparts of the two prevailing French types. Both specimens were thrown out by the workmen on the same day from the lowest bed of stratified gravel and sand, 13 feet thick, containing bones of the elephant, deer, and ox, and many freshwater shells. The two implements occurred at the depth of 13 feet from the surface of the soil, and rested immediately on solid beds of Oolitic limestone, as represented in the accompanying section (Figure 23). Having been invited by Mr. Wyatt to verify these facts, I went to Biddenham within a fortnight of the date of his discovery (April 1861), and, for the first time, saw evidence which satisfied me of the chronological relations of those three phenomena, the antique tools, the extinct mammalia, and the glacial formation. On that occasion I examined the pits in company with Messrs. Prestwich, Evans, and Wyatt, and we collected ten species of shells from the stratified drift Number 3, or the beds overlying the lowest gravel from which the flint implements had been exhumed. They were all of common fluviatile and land species now living in the same part of England. Since our visit, Mr. Wyatt has added to them Paludina marginata, Michaud (Hydrobia of some authors), a species of the South of France no longer inhabiting the British Isles. The same geologist has also found, since we were at Biddenham, several other flint tools of corresponding type, both there and at other localities in the valley of the Ouse, near Bedford. [Figure 23. Valley of the Ouse] (FIGURE 23. SECTION ACROSS THE VALLEY OF THE OUSE, TWO MILES WEST-NORTH-WEST OF BEDFORD.* (* Prestwich, "Quarterly Journal of the Geological Society" volume 17 1861 page 364; and Wyatt, "Geologist" 1861 page 242.) 1. Oolitic strata. 2. Boulder clay, or marine northern drift, rising to about ninety feet above the Ouse. 3. Ancient gravel, with elephant bones, freshwater shells, and flint implements. 4. Modern alluvium of the Ouse. a. Biddenham gravel pits, at the bottom of which flint tools were found.) The boulder clay Number 2 extends for miles in all directions, and was evidently once continuous from b to c before the valley was scooped out. It is a portion of the great marine glacial drift of the midland counties of England, and contains blocks, some of large size, not only of the Oolite of the neighbourhood, but of Chalk and other rocks transported from still greater distances, such as syenite, basalt, quartz, and New Red Sandstone. These erratic blocks of foreign origin are often polished and striated, having undergone what is called glaciation, of which more will be said by and by. Blocks of the same mineral character, embedded at Biddenham in the gravel Number 3, have lost all signs of this striation by the friction to which they were subjected in the old river bed. The great width of the valley of the Ouse, which is sometimes 2 miles, has not been expressed in the diagram. It may have been shaped out by the joint action of the river and the tides when this part of England was emerging from the waters of the glacial sea, the boulder clay being first cut through, and then an equal thickness of underlying Oolite. After this denudation, which may have accompanied the emergence of the land, the country was inhabited by the primitive people who fashioned the flint tools. The old river, aided perhaps by the continued upheaval of the whole country, or by oscillations in its level, went on widening and deepening the valley, often shifting its channel, until at length a broad area was covered by a succession of the earliest and latest deposits, which may have corresponded in age to the higher and lower gravels of the valley of the Somme, already described. At Biddenham, and elsewhere in the same gravel, remains of Elephas antiquus have been discovered, and Mr. Wyatt obtained, January 1863, a flint implement associated with bones and teeth of hippopotamus from gravel at Summerhouse hill, which lies east of Bedford, lower down the valley of the Ouse, and 4 miles from Biddenham. One step at least we gain by the Bedford sections, which those of Amiens and Abbeville had not enabled us to make. They teach us that the fabricators of the antique tools, and the extinct mammalia coeval with them, were all post-glacial. FLINT IMPLEMENTS IN A FRESHWATER DEPOSIT AT HOXNE IN SUFFOLK [17]. So early as the first year of the nineteenth century, a remarkable paper was communicated to the Society of Antiquaries by Mr. John Frere, in which he gave a clear description of the discovery at Hoxne, near Diss, in Suffolk, of flint tools of the type since found at Amiens, adding at the same time good geological reasons for presuming that their antiquity was very great, or, as he expressed it, beyond that of the present world, meaning the actual state of the physical geography of that region. "The flints," he said, "were evidently weapons of war, fabricated and used by a people who had not the use of metals. They lay in great numbers at the depth of about 12 feet in a stratified soil which was dug into for the purpose of raising clay for bricks. Under a foot and a half of vegetable earth was clay 7 1/2 feet thick, and beneath this one foot of sand with shells, and under this 2 feet of gravel, in which the shaped flints were found generally at the rate of 5 or 6 in a square yard. In the sandy beds with shells were found the jawbone and teeth of an enormous unknown animal. The manner in which the flint weapons lay would lead to the persuasion that it was a place of their manufacture, and not of their accidental deposit. Their numbers were so great that the man who carried on the brick-work told me that before he was aware of their being objects of curiosity, he had emptied baskets full of them into the ruts of the adjoining road." Mr. Frere then goes on to explain that the strata in which the flints occur are disposed horizontally, and do not lie at the foot of any higher ground, so that portions of them must have been removed when the adjoining valley was hollowed out. If the author had not mistaken the freshwater shells associated with the tools for marine species, there would have been nothing to correct in his account of the geology of the district, for he distinctly perceived that the strata in which the implements were embedded had, since that time, undergone very extensive denudation.* (* Frere, "Archaeologia" volume 13 1800 page 206.) Specimens of the flint spear-heads, sent to London by Mr. Frere, are still preserved in the British Museum, and others are in the collection of the Society of Antiquaries. [Illustration: Figure 24. Position of Flint Weapons] (FIGURE 24. SECTION SHOWING THE POSITION OF THE FLINT WEAPONS AT HOXNE, NEAR DISS, SUFFOLK. See Prestwich "Philosophical Transactions" Plate 11 1860.) 1. Gravel of Gold Brook, a tributary of the Waveney. 2. Higher-level gravel overlying the freshwater deposit. 3 and 4. Sand and gravel, with freshwater shells, and flint implements, and bones of mammalia. 5. Peaty and clayey beds, with same fossils. 6. Boulder clay or glacial drift. 7. Sand and gravel below boulder clay. 8. Chalk with flints.) Mr. Prestwich's attention was called by Mr. Evans to these weapons, as well as to Mr. Frere's memoir after his return from Amiens in 1859, and he lost no time in visiting Hoxne, a village five miles eastward of Diss. It is not a little remarkable that he should have found, after a lapse of sixty years, that the extraction of clay was still going on in the same brick-pit. Only a few months before his arrival, two flint instruments had been dug out of the clay, one from a depth of 7 and the other of 10 feet from the surface. Others have since been disinterred from undisturbed beds of gravel in the same pit. Mr. Amyot of Diss has also obtained from the underlying freshwater strata the astragalus of an elephant, and bones of the deer and horse; but although many of the old implements have recently been discovered in situ in regular strata and preserved by Sir Edward Kerrison, no bones of extinct mammalia seem as yet to have been actually seen in the same stratum with one of the tools. By reference to the annexed section, the geologist will see that the basin-shaped hollow a, b, c has been filled up gradually with the freshwater strata 3, 4, 5, after the same cavity a, b, c had been previously excavated out of the more ancient boulder clay Number 6. The relative position of these formations will be better understood when I have described in the twelfth chapter the structure of Norfolk and Suffolk as laid open in the sea-cliffs at Mundesley, about 30 miles distant from Hoxne, in a north-north-east direction. I examined the deposits at Hoxne in 1860, when I had the advantage of being accompanied by the Reverend J. Gunn and the Reverend S.W. King. In the loamy beds 3 and 4, Figure 24, we observed the common river shell Valvata piscinalis in great numbers. With it, but much more rare, were Limnaea palustris, Planorbis albus, P. Spirorbis, Succinea putris, Bithynia tentaculata, Cyclas cornea; and Mr. Prestwich mentions Cyclas amnica and fragments of a Unio, besides several land shells. In the black peaty mass Number 5, fragments of wood of the oak, yew, and fir have been recognised. The flint weapons which I have seen from Hoxne are so much more perfect, and have their cutting edge so much sharper than those from the valley of the Somme, that they seem neither to have been used by Man, nor to have been rolled in the bed of a river. The opinion of Mr. Frere, therefore, that there may have been a manufactory of weapons on the spot, appears probable. FLINT IMPLEMENTS AT ICKLINGHAM IN SUFFOLK. In another part of Suffolk, at Icklingham, in the valley of the Lark, below Bury St. Edmund's, there is a bed of gravel, in which teeth of Elephas primigenius and several flint tools, chiefly of a lance-head form, have been found. I have twice visited the spot, which has been correctly described by Mr. Prestwich.* (* "Quarterly Journal of the Geological Society" volume 17 1861, page 364.) The section of the Bedford tool-bearing alluvium, given in Figure 23, may serve to illustrate that of Icklingham, if we substitute Chalk for Oolite, and the river Lark for the Ouse. In both cases, the present bed of the river is about 30 feet below the level of the old gravel, and the Chalk hill, which bounds the valley of the Lark on the right side, is capped like the Oolite of Biddenham by boulder clay, which rises to the height of 100 feet above the Lark. About twelve years ago, a large erratic block, above 4 feet in diameter, was dug out of the boulder clay at Icklingham, which I found to consist of a hard siliceous schist, which must have come from a remote region. The tool-bearing gravel here, as in the case to which it has been compared near Bedford, is proved to be newer than the glacial drift, by containing pebbles of basalt and other rocks derived from that formation. CHAPTER 10. -- CAVERN DEPOSITS, AND PLACES OF SEPULTURE OF THE PLEISTOCENE PERIOD. Flint Implements in Cave containing Hyaena and other extinct Mammalia in Somersetshire. Caves of the Gower Peninsula in South Wales. Rhinoceros hemitoechus. Ossiferous Caves near Palermo. Sicily once part of Africa. Rise of Bed of the Mediterranean to the Height of three hundred Feet in the Human Period in Sardinia. Burial-place of Pleistocene Date of Aurignac in the South of France. Rhinoceros tichorhinus eaten by Man. M. Lartet on extinct Mammalia and Works of Art found in the Aurignac Cave. Relative Antiquity of the same considered. WORKS OF ART ASSOCIATED WITH EXTINCT MAMMALIA IN A CAVERN IN SOMERSETSHIRE. The only British cave from which implements resembling those of Amiens have been obtained, since the attention of geologists has been awakened to the importance of minutely observing the position of such relics relatively to the associated fossil mammalia, is that recently opened near Wells in Somersetshire. It occurs near the cave of Wookey Hole, from the mouth of which the river Axe issues on the southern flanks of the Mendips. No one had suspected that on the left side of the ravine, through which the river flows after escaping from its subterranean channel, there were other caves and fissures concealed beneath the green sward of the steep sloping bank. About ten years ago, a canal was made, several hundred yards in length, for the purpose of leading the waters of the Axe to a paper-mill, now occupying the middle of the ravine. In carrying out this work, about 12 feet of the left bank was cut away, and a cavernous fissure, choked up to the roof with ossiferous loam, was then, for the first time, exposed to view. This great cavity, originally 9 feet high and 36 wide, traversed the Dolomitic Conglomerate; and fragments of that rock, some angular and others water-worn, were scattered through the red mud of the cave, in which fossil remains were abundant. For an account of them and the position they occupied we are indebted to Mr. Dawkins, F.G.S., who, in company with Mr. Williamson, explored the cavern in 1859, and obtained from it the bones of the Hyaena spelaea in such numbers as to lead him to conclude that the cavern had for a long time been a hyaena's den. Among the accompanying animals found fossil in the same bone-earth, were observed Elephas primigenius, Rhinoceros tichorhinus, Ursus spelaeus, Bos primigenius, Megaceros hibernicus, Cervus tarandus (and other species of Cervus), Felis spelaea, Canis lupus, Canis vulpes, and teeth and bones of the genus Equus in great numbers. Intermixed with the above fossil bones were some arrowheads, made of bone, and many chipped flints, and chipped pieces of chert, a white or bleached flint weapon of the spearhead Amiens type, which was taken out of the undisturbed matrix by Mr. Williamson himself, together with a hyaena's tooth, showing that Man had either been contemporaneous with or had preceded the extinct fauna. After penetrating 34 feet from the entrance, Mr. Dawkins found the cave bifurcating into two branches, one of which was vertical. By this rent, perhaps, some part of the contents of the cave may have been introduced.* (* Boyd Dawkins, "Proceedings of the Geological Society" January 1862.) When I examined the spot in 1860, after I had been shown some remains of the hyaena collected there, I felt convinced that a complete revolution must have taken place in the topography of the district since the time of the extinct quadrupeds. I was not aware at the time that flint tools had been met with in the same bone-deposit. CAVES OF GOWER IN GLAMORGANSHIRE, SOUTH WALES. The ossiferous caves of the peninsula of Gower in Glamorganshire have been diligently explored of late years by Dr. Falconer and Lieutenant-Colonel E.R. Wood, who have thoroughly investigated the contents of many which were previously unknown. Among these Dr. Falconer's skilled eye has recognised the remains of almost every quadruped which he had elsewhere found fossil in British caves: in some places the Elephas primigenius, accompanied by its usual companion, the Rhinoceros tichorhinus, in others Elephas antiquus, associated with Rhinoceros hemitoechus, Falconer; the extinct animals being often embedded, as in the Belgian caves, in the same matrix with species now living in Europe, such as the common badger (Meles taxus), the common wolf, and the fox. In a cavernous fissure called the Raven's Cliff, teeth of several individuals of Hippopotamus major, both young and old, were found; and this in a district where there is now scarce a rill of running water, much less a river in which such quadrupeds could swim. In one of the caves, called Spritsail Tor, bones of the elephants above named were observed, with a great many other quadrupeds of Recent and extinct species. From one fissure, called Bosco's Den, no less than one thousand antlers of the reindeer, chiefly of the variety called Cervus Guettardi, were extracted by the persevering exertions of Colonel Wood, who estimated that several hundred more still remained in the bone-earth of the same rent. They were mostly shed horns, and of young animals; and had been washed into the rent with other bones, and with angular fragments of limestone, and all enveloped in the same ochreous mud. Among the other bones, which were not numerous, were those of the cave-bear, wolf, fox, ox, stag, and field-mouse. But the discovery of most importance, as bearing on the subject of the present work, is the occurrence in a newly-discovered cave, called Long Hole, by Colonel Wood, in 1861, of the remains of two species of rhinoceros, R. tichorhinus and R. hemitoechus, Falconer, in an undisturbed deposit, in the lower part of which were some well-shaped flint knives, evidently of human workmanship. It is clear from their position that Man was coeval with these two species. We have elsewhere independent proofs of his co-existence with every other species of the cave-fauna of Glamorganshire; but this is the first well-authenticated example of the occurrence of R. hemitoechus in connection with human implements. In the fossil fauna of the valley of the Thames, Rhinoceros leptorhinus was mentioned as occurring at Gray's Thurrock with Elephas antiquus. Dr. Falconer, in a memoir which he is now preparing for the press on the European Pliocene and Pleistocene species of the genus Rhinoceros, has shown that, under the above name of R. leptorhinus, three distinct species have been confounded by Cuvier, Owen, and other palaeontologists:-- 1. R. megarhinus, Christol, being the original and typical R. leptorhinus of Cuvier, founded on Cortesi's Monte Zago cranium, and the ONLY Pliocene, or Pleistocene European species, that had not a nasal septum.--Gray's Thurrock, etc. 2. R. hemitoechus, Falconer, in which the ossification of the septum dividing the nostrils is incomplete in the middle, besides other cranial and dental characters distinguishing it from R. tichorhinus, accompanies Elephas antiquus in most of the oldest British bone-caves, such as Kirkdale, Cefn, Durdham Down, Minchin Hole, and other Gower caverns--also found at Clacton, in Essex, and in Northamptonshire. 3. R. etruscus, Falconer, a comparatively slight and slender form, also with an incomplete bony septum,* occurs deep in the Val d'Arno deposits, and in the "Forest bed," and superimposed blue clays, with lignite, of the Norfolk coast, but nowhere as yet found in the ossiferous caves in Britain. (* Falconer, "Quarterly Journal of the Geological Society" volume 15 1859 page 602.) Dr. Falconer announced in 1860 his opinion that the filling up of the Gower caves in South Wales took place after the deposition of the marine boulder clay,* an opinion in harmony with what we have since learnt from the section of the gravels near Bedford, given above (Figure 23), where a fauna corresponding to that of the Welsh caves characterises the ancient alluvium, and is shown to be clearly post-glacial, in the sense of being posterior in date to the boulder-clay of the midland counties. (* Ibid. volume 16 1860 page 491.) In the same sense the late Edward Forbes declared, in 1846, his conviction that not only the Cervus megaceros, but also the mammoth and other extinct pachyderms and carnivora, had lived in Britain in post-glacial times.* (* "Memoir of the Geological Survey" pages 394 to 397.) The Gower caves in general have their floors strewed over with sand, containing marine shells, all of living species; and there are raised beaches on the adjoining coast, and other geological signs of great alteration in the relative level of land and sea, since that country was inhabited by the extinct mammalia, some of which, as we have seen, were certainly coeval with Man. OSSIFEROUS CAVES IN THE NORTH OF SICILY. Geologists have long been familiar with the fact that on the northern coast of Sicily, between Termini on the east, and Trapani on the west, there are several caves containing the bones of extinct animals. These caves are situated in rocks of Hippurite limestone, a member of the Cretaceous series, and some of them may be seen on both sides of the Bay of Palermo. If in the neighbourhood of that city we proceed from the sea inland, ascending a sloping terrace, composed of the marine Newer Pliocene strata, we reach about a mile from the shore, and at the height of about 180 feet above it a precipice of limestone, at the base of which appear the entrances of several caves. In that of San Ciro, on the east side of the bay, we find at the bottom sand with marine shells, forty species of which have been examined, and found almost all to agree specifically with mollusca now inhabiting the Mediterranean. Higher in position, and resting on the sand, is a breccia, composed of pieces of limestone, quartz, and schist in a matrix of brown marl, through which land shells are dispersed, together with bones of two species of hippopotamus, as determined by Dr. Falconer. Certain bones of the skeleton were counted in such numbers as to prove that they must have belonged to several hundred individuals. With these were associated the remains of Elephas antiquus, and bones of the genera Bos, Cervus, Sus, Ursus, Canis, and a large Felis. Some of these bones have been rolled as if partially subjected to the action of water, and may have been introduced by streams through rents in the Hippurite limestone; but there is now no running water in the neighbourhood, no river such as the hippopotamus might frequent, not even a small brook, so that the physical geography of the district must have been altogether changed since the time when such remains were swept into fissures, or into the channels of engulfed rivers. No proofs seem yet to have been found of the existence of Man at the period when the hippopotamus and Elephas antiquus flourished at San Ciro. But there is another cave called the Grotto di Maccagnone, which much resembles it in geological position, on the opposite or west side of the Bay of Palermo, near Carini. In the bottom of this cave a bone deposit like that of San Ciro occurs, and above it other materials reaching to the roof, and evidently washed in from above, through crevices in the limestone. In this upper and newer breccia Dr. Falconer discovered flint knives, bone splinters, bits of charcoal, burnt clay, and other objects indicating human intervention, mingled with entire land shells, teeth of horses, coprolites of hyaenas, and other bones, the whole agglutinated to one another and to the roof by the infiltration of water holding lime in solution. The perfect condition of the large fragile helices (Helix vermiculata) afforded satisfactory evidence, says Dr. Falconer, that the various articles were carried into the cave by the tranquil agency of water, and not by any tumultuous action. At a subsequent period other geographical changes took place, so that the cave, after it had been filled, was washed out again, or emptied of its contents with the exception of those patches of breccia which, being cemented together by stalactite, still adhere to the roof.* (* "Quarterly Journal of the Geological Society" volume 16 1860 page 105.) Baron Anca, following up these investigations, explored, in 1859, another cave at Mondello, west of Palermo, and north of Mount Gallo, where he discovered molars of the living African elephant, and afterwards additional specimens of the same species in the neighbouring grotto of Olivella. In reference to this elephant, Dr. Falconer has reminded us that the distance between the nearest part of Sicily and the coast of Africa, between Marsala and Cape Bon, is not more than 80 miles, and Admiral Smyth, in his Memoir on the Mediterranean, states (page 499) that there is a subaqueous plateau, named by him Adventure Bank, uniting Sicily to Africa by a succession of ridges which are not more than from 40 to 50 fathoms under water.* (* Cited by Horner, "Presidential Address to the Geological Society" 1861 page 42.) Sicily therefore might be re-united to Africa by movements of upheaval not greater than those which are already known to have taken place within the human period on the borders of the Mediterranean, of which I shall now proceed to cite a well-authenticated example, observed in Sardinia. RISE OF THE BED OF THE SEA TO THE HEIGHT OF 300 FEET, IN THE HUMAN PERIOD, IN SARDINIA. Count Albert de la Marmora, in his description of the geology of Sardinia,* has shown that on the southern coast of that island, at Cagliari and in the neighbourhood, an ancient bed of the sea, containing marine shells of living species, and numerous fragments of antique pottery, has been elevated to the height of from 230 to 324 feet above the present level of the Mediterranean. (* "Partie Geologique" volume 1 pages 382 and 387.) Oysters and other shells, of which a careful list has been published, including the common mussel (Mytilus edulis), many of them having both valves united, occur, embedded in a breccia in which fragments of limestone abound. The mussels are often in such numbers as to impart, when they have decomposed, a violet colour to the marine stratum. Besides pieces of coarse pottery, a flattened ball of baked earthenware, with a hole through its axis, was found in the midst of the marine shells. It is supposed to have been used for weighting a fishing net. Of this and of one of the fragments of ancient pottery Count de la Marmora has given figures. The upraised bed of the sea probably belongs in this instance to the Pleistocene period, for in a bone breccia, filling fissures in the rocks around Cagliari, the remains of extinct mammalia have been detected; among which is a new genus of carnivorous quadruped, named Cynotherium by M. Studiati, and figured by Count de la Marmora in his Atlas (Plate 7), also an extinct species of Lagomys, determined by Cuvier in 1825. Embedded in the same bone-breccia, and enveloped with red earth like the mammalian remains, were detected shells of the Mytilus edulis before mentioned, implying that the marine formation containing shells and pottery had been already upheaved and exposed to denudation before the remains of quadrupeds were washed into these rents and included in the red earth. In the vegetable soil covering the upraised marine stratum, fragments of Roman pottery occur. If we assume the average rate of upheaval to have been, as before hinted, 2 1/2 feet in a century, 300 feet would give an antiquity of 12,000 years to the Cagliari pottery, even if we simply confine our estimate to the upheaval above the sea-level, without allowing for the original depth of water in which the mollusca lived. Even then our calculation would merely embrace the period during which the upward movement was going on; and we can form at present no conjecture as to the probable era of its commencement or termination. I learn from Captain Spratt, R.N., that the island of Crete or Candia, about 135 miles in length, has been raised at its western extremity about 25 feet; so that ancient ports are now high and dry above the sea, while at its eastern end it has sunk so much that the ruins of old towns are seen under water. Revolutions like these in the physical geography of the countries bordering the Mediterranean, may well help us to understand the phenomena of the Palermo caves, and the presence in Sicily of African species of mammalia. CLIMATE AND HABITS OF THE HIPPOPOTAMUS. As I have alluded more than once in this chapter to the occurrence of the remains of the hippopotamus in places where there are now no rivers, not even a rill of water, and as other bones of the same genus have been met with in the lower-level gravels of the Somme where large blocks of sandstone seem to imply that ice once played a part in their transportation, it may be well to consider, before proceeding farther, what geographical and climatal conditions are indicated by the presence of these fossil pachyderms. It is now very generally conceded that the mammoth and tichorhine rhinoceros were fitted to inhabit northern regions, and it is therefore natural to begin by asking whether the extinct hippopotamus may not in like manner have flourished in a cold climate. In answer to this inquiry, it has been remarked that the living hippopotami, anatomically speaking so closely allied to the extinct species, are so aquatic and fluviatile in their habits as to make it difficult to conceive that their congeners could have thriven all the year round in regions where, during winter, the rivers were frozen over for months. Moreover, I have been unable to learn that, in any instance, bones of the hippopotamus have been found in the drift of northern Germany associated with the remains of the mammoth, tichorhine rhinoceros, musk-ox, reindeer, lemming, and other arctic quadrupeds before alluded to; yet, though not proved to have ever made a part of such a fauna, the presence of the fossil hippopotamus north of the fiftieth parallel of latitude naturally tempts us to speculate on the migratory powers and instincts of some of the extinct species of the genus. They may have resembled, in this respect, the living musk-ox, herds of which pass for hundreds of miles over the ice to the rich pastures of Melville Island, and then return again to southern latitudes before the ice breaks up. We are indebted to Sir Andrew Smith,* an experienced zoologist, for having given us an account of the migratory habits of the living hippopotamus of Southern Africa (H. amphibius, Linn.). (* "Illustrations of the Zoology of South Africa": article "Hippopotamus.") He states that, when the Dutch first colonised the Cape of Good Hope, this animal abounded in all the great rivers, as far south as the land extends; whereas, in 1849, they had all disappeared, scarcely one remaining even within a moderate distance of the colony. He also tells us that this species evinces great sagacity in changing its quarters whenever danger threatens, quitting every district invaded by settlers bearing fire-arms. Bulky as they are, they can travel speedily for miles over land from one pool of a dried-up river to another; but it is by water that their powers of locomotion are surpassingly great, not only in rivers, but in the sea, for they are far from confining themselves to fresh water. Indeed, Sir A. Smith finds it "difficult to decide whether, during the daytime and when not feeding, they prefer the pools of rivers or the waters of the ocean for their abode." In districts where they have been disturbed by Man, they feed almost entirely in the night, chiefly on certain kinds of grass, but also on brushwood. Sir A. Smith relates that, in an expedition which he made north of Port Natal, he found them swarming in all the rivers about the tropic of Capricorn. Here they were often seen to have left their footprints on the sands, entering or coming out of the salt water; and on one occasion Smith's party tried in vain to intercept a female with her young as she was making her way to the sea. Another female, which they had wounded on her precipitate retreat to the sea, was afterwards shot in that element. The geologist, therefore, may freely speculate on the time when herds of hippopotami issued from North African rivers, such as the Nile, and swam northwards in summer along the coasts of the Mediterranean, or even occasionally visited islands near the shore. Here and there they may have landed to graze or browse, tarrying awhile and afterwards continuing their course northwards. Others may have swum in a few summer days from rivers in the south of Spain or France to the Somme, Thames, or Severn, making timely retreat to the south before the snow and ice set in. BURIAL-PLACE AT AURIGNAC, IN THE SOUTH OF FRANCE, OF PLEISTOCENE DATE. I have alluded in the beginning of the fourth chapter to a custom prevalent among rude nations of consigning to the tomb works of art, once the property of the dead, or objects of their affection, and even of storing up, in many cases, animal food destined for the manes of the defunct in a future life. I also cited M. Desnoyers' comments on the absence among the bones of wild and domestic animals found in old Gaulish tombs of all intermixture of extinct species of quadrupeds, as proving that the oldest sepulchral monuments then known in France (1845) had no claims to high antiquity founded on palaeontological data. M. Lartet, however, has recently published a circumstantial account of what seems clearly to have been a sepulchral vault of the Pleistocene period, near Aurignac, not far from the foot of the Pyrenees. I have had the advantage of inspecting the fossil bones and works of art obtained by him from that grotto, and of conversing and corresponding with him on the subject, and can see no grounds for doubting the soundness of his conclusions.* (* See Lartet, "Annales des Sci. Nat." 4mo. Ser. Zoologie volume 15 page 177 translated in "Natural History Review" London January 1862.) [Illustration: Figure 25. Hill of Fajoles] (FIGURE 25. SECTION OF PART OF THE HILL OF FAJOLES PASSING THROUGH THE SEPULCHRAL GROTTO OF AURIGNAC (E. Lartet). a. Part of the vault in which the remains of seventeen human skeletons were found. b. Layer of made ground, two feet thick, inside the grotto in which a few human bones, with entire bones of extinct and living species of animals, and many works of art were embedded. c. Layers of ashes and charcoal, six inches thick, with broken, burnt, and gnawed bones of extinct and Recent mammalia; also hearth-stones and works of art; no human bones. d. Deposit with similar contents and a few scattered cinders. e. Talus of rubbish washed down from the hill above. f, g. Slab of rock which closed the vault, not ascertained whether it extended to h. f i. Rabbit burrow which led to the discovery of the grotto. h, k. Original terrace on which the grotto opened. N. Nummulitic limestone of hill of Fajoles.) The town of Aurignac is situated in the department of the Haute-Garonne, near a spur of the Pyrenees; adjoining it is the small flat-topped hill of Fajoles, about 60 feet above the brook called Rodes, which flows at its foot on one side. It consists of Nummulitic limestone, presenting a steep escarpment towards the north-west, on which side in the face of the rock, about 45 feet above the brook, is now visible the entrance of a grotto a, Figure 25, which opened originally on the terrace h, c, k, which slopes gently towards the valley. Until the year 1852, the opening into this grotto was masked by a talus of small fragments of limestone and earthy matter e, such as the rain may have washed down the slope of the hill. In that year a labourer named Bonnemaison, employed in repairing the roads, observed that rabbits, when hotly pursued by the sportsman, ran into a hole which they had burrowed in the talus, at i f, Figure 25. On reaching as far into the opening as the length of his arm, he drew out, to his surprise, one of the long bones of the human skeleton; and his curiosity being excited, and having a suspicion that the hole communicated with a subterranean cavity, he commenced digging a trench through the middle of the talus, and in a few hours found himself opposite a large heavy slab of rock f h, placed vertically against the entrance. Having removed this, he discovered on the other side of it an arched cavity a, 7 or 8 feet in its greatest height, 10 in width, and 7 in horizontal depth. It was almost filled with bones, among which were two entire skulls, which he recognised at once as human. The people of Aurignac, astonished to hear of the occurrence of so many human relics in so lonely a spot, flocked to the cave, and Dr. Amiel, the Mayor, ordered all the bones to be taken out and reinterred in the parish cemetery. But before this was done, having as a medical man a knowledge of anatomy, he ascertained by counting the homologous bones that they must have formed parts of no less than seventeen skeletons of both sexes, and all ages; some so young that the ossification of some of the bones was incomplete. Unfortunately the skulls were injured in the transfer; and what is worse, after the lapse of eight years, when M. Lartet visited Aurignac, the village sexton was unable to tell him in what exact place the trench was dug, into which the skeletons had been thrown, so that this rich harvest of ethnological knowledge seems for ever lost to the antiquary and geologist. M. Lartet having been shown, in 1860, the remains of some extinct animals and works of art, found in digging the original trench made by Bonnemaison through the bed d under the talus, and some others brought out from the interior of the grotto, determined to investigate systematically what remained intact of the deposits outside and inside the vault, those inside, underlying the human skeletons, being supposed to consist entirely of made ground. Having obtained the assistance of some intelligent workmen, he personally superintended their labours, and found outside the grotto, resting on the sloping terrace h k, the layer of ashes and charcoal c, about 6 inches thick, extending over an area of 6 or 7 square yards, and going as far as the entrance of the grotto and no farther, there being no cinders or charcoal in the interior. Among the cinders outside the vault were fragments of fissile sandstone, reddened by heat, which were observed to rest on a levelled surface of Nummulitic limestone and to have formed a hearth. The nearest place from whence such slabs of sandstone could have been brought was the opposite side of the valley. Among the ashes, and in some overlying earthy layers, d, separating the ashes from the talus e, were a great variety of bones and implements; amongst the latter not fewer than a hundred flint articles--knives, projectiles, sling stones, and chips, and among them one of those siliceous cores or nuclei with numerous facets, from which flint flakes or knives had been struck off, seeming to prove that some instruments were occasionally manufactured on the very spot. Among other articles outside the entrance was found a stone of a circular form, and flattened on two sides, with a central depression, composed of a tough rock which does not belong to that region of the Pyrenees. This instrument is supposed by the Danish antiquaries to have been used for removing by skilful blows the edges of flint knives, the fingers and thumb being placed in the two opposite depressions during the operation. Among the bone instruments were arrows without barbs, and other tools made of reindeer horn, and a bodkin formed out of the more compact horn of the roedeer. This instrument was well shaped, and sharply pointed, and in so good a state of preservation that it might still be used for piercing the tough skins of animals. Scattered through the same ashes and earth were the bones of the various species of animals enumerated in the subjoined lists, with the exception of two, marked with an asterisk, which only occurred in the interior of the grotto:-- TABLE 10/1. NUMBERS OF INDIVIDUALS, BONES OF WHICH WERE FOUND IN THE AURIGNAC CAVE. COLUMN 1: NAME OF SPECIES. COLUMN 2: NUMBER OF INDIVIDUALS. 1. CARNIVORA 1. Ursus spelaeus (cave-bear): 5 to 6. 2. Ursus arctos? (brown bear): 1. 3. Meles taxus (badger): 1 to 2. 4. Putorius vulgaris (polecat): 1. 5. *Felis spelaea (cave-lion): 1. 6. Felis catus ferus (wild cat): 1. 7. Hyaena spelaea (cave-hyaena): 5 to 6. 8. Canis lupus (wolf): 3. 9. Canis vulpes (fox): 18 to 20. 2. HERBIVORA. 1. Elephas primigenius (mammoth, two molars). 2. Rhinoceros tichorhinus (Siberian rhinoceros): 1. 3. Equus caballus (horse): 12 to 15. 4. Equus asinus (?) (ass): 1. 5. *Sus scrofa (pig, two incisors). 6. Cervus elaphus (stag): 1. 7. Megaceros hibernicus (gigantic Irish deer): 1. 8. C. capreolus (roebuck): 3 to 4. 9. C. tarandus (reindeer): 10 to 12. 10. Bison europaeus (aurochs): 12 to 15. The bones of the herbivora were the most numerous, and all those on the outside of the grotto which had contained marrow were invariably split open, as if for its extraction, many of them being also burnt. The spongy parts, moreover, were wanting, having been eaten off and gnawed after they were broken, the work, according to M. Lartet, of hyaenas, the bones and coprolites of which were mixed with the cinders, and dispersed through the overlying soil d. These beasts of prey are supposed to have prowled about the spot and fed on such relics of the funeral feasts as remained after the retreat of the human visitors, or during the intervals between successive funeral ceremonies which accompanied the interment of the corpses within the sepulchre. Many of the bones were also streaked, as if the flesh had been scraped off by a flint instrument. Among the various proofs that the bones were fresh when brought to the spot, it is remarked that those of the herbivora not only bore the marks of having had the marrow extracted and having afterwards been gnawed and in part devoured as if by carnivorous beasts, but that they had also been acted upon by fire (and this was especially noticed in one case of a cave-bear's bone), in such a manner as to show that they retained in them at the time all their animal matter. Among other quadrupeds which appear to have been eaten at the funeral feasts, and of which the bones occurred among the ashes, were those of a young Rhinoceros tichorhinus, the bones of which had been, like those of the accompanying herbivora, broken and gnawed by a beast of prey at both extremities. Outside of the great slab of stone forming the door, not one human bone occurred; inside of it there were found, mixed with loose soil, the remains of as many as seventeen human individuals, besides some works of art and bones of animals. We know nothing of the arrangement of these bones when they were first broken into. M. Lartet inferred at first that the bodies were bent down upon themselves in a squatting attitude, a posture known to have been adopted in most of the sepulchres of primitive times; and he has so represented them in his restoration of the cave: but this opinion he has since retracted. His artist also has inadvertently, in the same drawing, delineated the arched grotto as if it were shaped very regularly and smoothly, like a finished piece of masonry, whereas the surface was in truth as uneven and irregular as are the roofs of all natural grottos. There was no stalagmite in the grotto, and M. Lartet, an experienced investigator of ossiferous caverns in the south of France, came to the conclusion that all the bones and soil found in the inside were artificially introduced. The substratum b, Figure 25, which remained after the skeletons had been removed, was about 2 feet thick. In it were found about ten detached human bones, including a molar tooth; and M. Delesse ascertained by careful analysis of one of these, as well as of the bones of a rhinoceros, bear, and some other extinct animals, that they all contained precisely the same proportion of nitrogen, or had lost an equal amount of their animal matter. My friend Mr. Evans, before cited, has suggested to me that such a fact, taken alone, may not be conclusive in favour of the equal antiquity of the human and other remains. No doubt, had the human skeletons been found to contain more gelatine than those of the extinct mammalia, it would have shown that they were the more modern of the two; but it is possible that after a bone has gone on losing its animal matter up to a certain point, it may then part with no more so long as it continues enveloped in the same matrix. If this be so, it follows that bones of very different degrees of antiquity, after they have lain for many thousands of years in a particular soil, may all have reached long ago the maximum of decomposition attainable in such a matrix. In the present case, however, the proof of the contemporaneousness of Man and the extinct animals does not depend simply on the identity of their mineral condition. The chemical analysis of M. Delesse is only a fact in corroboration of a great mass of other evidence. Mixed with the human bones inside the grotto first removed by Bonnemaison, were eighteen small, round, and flat plates of a white shelly substance, made of some species of cockle (Cardium), pierced through the middle as if for being strung into a bracelet. In the substratum also in the interior examined by M. Lartet was found the tusk of a young Ursus spelaeus, the crown of which had been stripped of its enamel, and which had been carved perhaps in imitation of the head of a bird. It was perforated lengthwise as if for suspension as an ornament or amulet. A flint knife also was found in the interior which had evidently never been used; in this respect, unlike the numerous worn specimens found outside, so that it is conjectured that it may, like other associated works of art, have been placed there as part of the funeral ceremonies. A few teeth of the cave-lion, Felis spelaea, and two tusks of the wild boar, also found in the interior, were memorials perhaps of the chase. No remains of the same animals were met with among the external relics. On the whole, the bones of animals inside the vault offer a remarkable contrast to those of the exterior, being all entire and uninjured, none of them broken, gnawed, half-eaten, scraped, or burnt like those lying among the ashes on the other side of the great slab which formed the portal. The bones of the interior seem to have been clothed with their flesh when buried in the layer of loose soil strewed over the floor. In confirmation of this idea, many bones of the skeleton were often observed to be in juxtaposition, and in one spot all the bones of the leg of an Ursus spelaeus were lying together uninjured. Add to this, the entire absence in the interior of cinders and charcoal, and we can scarcely doubt that we have here an example of an ancient place of sepulture, closed at the opening so effectually against the hyaenas or other carnivora that no marks of their teeth appear on any of the bones, whether human or brute. John Carver, in his travels in the interior of North America in a 1766-68 (chapter 15.), gave a minute account of the funeral rites of an Indian tribe which inhabited the country now called Iowa, at the junction of the St. Peter's River with the Mississippi; and Schiller, in his famous "Nadowessische Todtenklage," has faithfully embodied in a poetic dirge all the characteristic features of the ceremonies so graphically described by the English traveller, not omitting the many funeral gifts which, we are told, were placed "in a cave" with the bodies of the dead. The lines beginning, "Bringet her die letzten Gaben," have been thus translated, truthfully, and with all the spirit of the original, by Sir E. L. Bulwer*:-- "Here bring the last gifts!--and with these The last lament be said; Let all that pleased, and yet may please, Be buried with the dead. "Beneath his head the hatchet hide, That he so stoutly swung; And place the bear's fat haunch beside-- The journey hence is long! "And let the knife new sharpened be That on the battle-day Shore with quick strokes--he took but three-- The foeman's scalp away! "The paints that warriors love to use, Place here within his hand, That he may shine with ruddy hues Amidst the spirit-land." (* "Poems and Ballads of Schiller.") If we accept M. Lartet's interpretation of the ossiferous deposits of Aurignac, both inside and outside the grotto, they add nothing to the palaeontological evidence in favour of Man's antiquity, for we have seen all the same mammalia associated elsewhere with flint implements, and some species, such as the Elephas antiquus, Rhinoceros hemitoechus, and Hippopotamus major, missing here, have been met with in other places. An argument, however, having an opposite leaning may perhaps be founded on the phenomena of Aurignac. It may--indeed it has been said, that they imply that some of the extinct mammalia survived nearly to our times: First--Because of the modern style of the works of art at Aurignac. Secondly--Because of the absence of any signs of change in the physical geography of the country since the cave was used for a place of sepulture. In reference to the first of these propositions, the utensils, it is said, of bone and stone indicate a more advanced state of the arts than the flint implements of Abbeville and Amiens. M. Lartet, however, is of opinion that they do not, and thinks that we have no right to assume that the fabricators of the various spear-headed and other tools of the Valley of the Somme possessed no bone instruments or ornaments resembling those discovered at Aurignac. These last, moreover, he regards as extremely rude in comparison with others of the stone period in France, which can be proved palaeontologically, at least by strong negative evidence, to be of subsequent date. Thus, for example, at Savigne, near Civray, in the department of Vienne, there is a cave in which there are no extinct mammalia, but where remains of the reindeer abound. The works of art of the stone period found there indicate considerable progress in skill beyond that attested by the objects found in the Aurignac grotto. Among the Savigne articles, there is the bone of a stag, on which figures of two animals, apparently meant for deer, are engraved in outline, as if by a sharp-pointed flint. In another cave, that of Massat, in the department of Ariege, which M. Lartet ascribes to the period of the aurochs, a quadruped which survived the reindeer in the south of France, there are bone instruments of a still more advanced state of the arts, as, for example, barbed arrows with a small canal in each, believed to have served for the insertion of poison; also a needle of bird's bone, finely shaped, with an eye or perforation at one end, and a stag's horn, on which is carved a representation of a bear's head, and a hole at one end as if for suspending it. In this figure we see, says M. Lartet, what may perhaps be the earliest known example of lines used to express shading. The fauna of the aurochs (Bison europaeus) agrees with that of the earlier lake dwellings in Switzerland, in which hitherto the reindeer is wanting; whereas the reindeer has been found in a Swiss cave, in Mont Saleve, supposed by Lartet to be more ancient than the lake dwellings. According to this view, the mammalian fauna has undergone at least two fluctuations since the remains of some extinct quadrupeds were eaten, and others buried as funeral gifts in the sepulchral vault of Aurignac. As to the absence of any marked changes in the physical configuration of the district since the same grotto was a place of sepulture, we must remember that it is the normal state of the earth's surface to be undergoing great alterations in one place, while other areas, often in close proximity, remain for ages without any modification. In one region, rivers are deepening and widening their channels, or the waves of the sea are undermining cliffs, or the land is sinking beneath or rising above the waters, century after century, or the volcano is pouring forth torrents of lava or showers of ashes; while, in tracts hard by, the ancient forest, or extensive heath, or the splendid city continue scatheless and motionless. Had the talus which concealed from view the ancient hearth with its cinders and the massive stone portal of the Aurignac grotto escaped all human interference for thousands of years to come, there is no reason to suppose that the small stream at the foot of the hill of Fajoles would have undermined it. At the end of a long period the only alteration might have been the thickening of the talus which protected the loose cinders and bones from waste. We behold in many a valley of Auvergne, within 50 feet of the present river channel, a volcanic cone of loose ashes, with a crater at its summit, from which powerful currents of basaltic lava have poured, usurping the ancient bed of the torrent. By the action of the stream, in the course of ages, vast masses of the hard columnar basalt have been removed, pillar after pillar, and much vesicular lava, as in the case, for example, of the Puy Rouge, near Chalucet, and of the Puy de Tartaret, near Nechers.* (* Scrope's "Volcanoes of Central France" 1858 page 97.) The rivers have even in some cases, as the Sioule, near Chalucet, cut through not only the basalt which dispossessed them of their ancient channels, but have actually eaten 50 feet into the subjacent gneiss; yet the cone, an incoherent heap of scoriae and spongy ejectamenta, stands unmolested. Had the waters once risen, even for a day, so high as to reach the level of the base of one of these cones--had there been a single flood 50 or 60 feet in height since the last eruption occurred, a great part of these volcanoes must inevitably have been swept away as readily as all traces of the layer of cinders; and the accompanying bones would have been obliterated by the Rodes near Aurignac, had it risen, since the days of the mammoth, rhinoceros, and cave-bear, 50 feet above its present level. The Aurignac cave adds no new species to the list of extinct quadrupeds, which we have elsewhere, and by independent evidence, ascertained to have once flourished contemporaneously with Man. But if the fossil memorials have been correctly interpreted--if we have here before us at the northern base of the Pyrenees a sepulchral vault with skeletons of human beings, consigned by friends and relatives to their last resting-place--if we have also at the portal of the tomb the relics of funeral feasts, and within it indications of viands destined for the use of the departed on their way to a land of spirits; while among the funeral gifts are weapons wherewith in other fields to chase the gigantic deer, the cave-lion, the cave-bear, and woolly rhinoceros--we have at last succeeded in tracing back the sacred rites of burial, and, more interesting still, a belief in a future state, to times long anterior to those of history and tradition. Rude and superstitious as may have been the savage of that remote era, he still deserved, by cherishing hopes of a hereafter, the epithet of "noble," which Dryden gave to what he seems to have pictured to himself as the primitive condition of our race, "as Nature first made Man When wild in woods the noble savage ran."* (* "Siege of Granada" Part 1 Act 1 Scene 1.) CHAPTER 11. -- AGE OF HUMAN FOSSILS OF LE PUY IN CENTRAL FRANCE AND OF NATCHEZ ON THE MISSISSIPPI DISCUSSED. Question as to the Authenticity of the Fossil Man of Denise, near Le Puy-en-Velay, considered. Antiquity of the Human Race implied by that Fossil. Successive Periods of Volcanic Action in Central France. With what Changes in the Mammalian Fauna they correspond. The Elephas meridionalis anterior in Time to the Implement-bearing Gravel of St. Acheul. Authenticity of the Human Fossil of Natchez on the Mississippi discussed. The Natchez Deposit, containing Bones of Mastodon and Megalonyx, probably not older than the Flint Implements of St. Acheul. Among the fossil remains of the human species supposed to have claims to high antiquity, and which have for many years attracted attention, two of the most prominent examples are:-- First--"The fossil man of Denise," comprising the remains of more than one skeleton, found in a volcanic breccia near the town of Le Puy-en-Velay, in Central France. Secondly--The fossil human bone of Natchez, on the Mississippi, supposed to have been derived from a deposit containing remains of Mastodon and Megalonyx. Having carefully examined the sites of both of these celebrated fossils, I shall consider in this chapter the nature of the evidence on which the remote date of their entombment is inferred. FOSSIL MAN OF DENISE. An account of the fossil remains, so called, was first published in 1844 by M. Aymard of Le Puy, a writer of deservedly high authority both as a palaeontologist and archaeologist.* (* "Bulletin de la Societe Geologique de France" 1844, 1845, 1847.) M. Pictet, after visiting Le Puy and investigating the site of the alleged discovery, was satisfied that the fossil bones belonged to the period of the last volcanic eruptions of Velay; but expressly stated in his important treatise on palaeontology that this conclusion, though it might imply that Man had co-existed with the extinct elephant, did not draw with it the admission that the human race was anterior in date to the filling of the caverns of France and Belgium with the bones of extinct mammalia.* (* "Traite de Paleontologie" volume 1 1853 page 152.) At a meeting of the "Scientific Congress" of France, held at Le Puy in 1856, the question of the age of the Denise fossil bones was fully gone into, and in the report of their proceedings published in that year, the opinions of some of the most skilful osteologists respecting the point in controversy are recorded. The late Abbe Croizet, a most experienced collector of fossil bones in the volcanic regions of Central France, and an able naturalist, and the late M. Laurillard, of Paris, who assisted Cuvier in modelling many fossil bones, and in the arrangement of the museum of the Jardin, declared their opinion that the specimen preserved in the museum of Le Puy is no counterfeit. They believed the human bones to have been enveloped by natural causes in the tufaceous matrix in which we now see them. In the year 1859, Professor Hebert and M. Lartet visited Le Puy, expressly to investigate the same specimen, and to inquire into the authenticity of the bones and their geological age. Later in the same year, I went myself to Le Puy, having the same object in view, and had the good fortune to meet there my friend Mr. Poulett Scrope, with whom I examined the Montagne de Denise, where a peasant related to us how he had dug out the specimen with his own hands and in his own vineyard, not far from the summit of the volcano. I employed a labourer to make under his directions some fresh excavations, following up those which had been made a month earlier by MM. Hebert and Lartet, in the hope of verifying the true position of the fossils, but all of us without success. We failed even to find in situ any exact counterpart of the stone of the Le Puy Museum. The osseous remains of that specimen consist of a frontal and some other parts of the skull, including the upper jaw with teeth, both of an adult and young individual; also a radius, some lumbar vertebrae, and some metatarsal bones. They are all embedded in a light porous tuff, resembling in colour and mineral composition the ejectamenta of several of the latest eruptions of Denise. But none of the bones penetrate into another part of the same specimen, which consists of a more compact rock thickly laminated. Nevertheless, I agree with the Abbe Croizet and M. Aymard, that it is not conceivable even that the less coherent part of the museum Specimen which envelopes the human bones should have been artificially put together, whatever may have been the origin of certain other slabs of tuff which were afterwards sold as coming from the same place, and which also contained human remains. Whether some of these were spurious or not is a question more difficult to decide. One of them, now in the possession of M. Pichot-Dumazel, an advocate of Le Puy, is suspected of having had some plaster of Paris introduced into it to bind the bones more firmly together in the loose volcanic tuff. I was assured that a dealer in objects of natural history at Le Puy had been in the habit of occasionally securing the cohesion in that manner of fragments of broken bones, and the juxtaposition of uninjured ones found free and detachable in loose volcanic tuffs. From this to the fabrication of a factitious human fossil was, it is suggested, but a short step. But in reference to M. Pichot's specimen, an expert anatomist remarked to me that it would far exceed the skill, whether of the peasant who owned the vineyard or of the dealer above mentioned, to put together in their true position all the thirty-eight bones of the hand and fingers, or the sixteen of the wrist, without making any mistake, and especially without mixing those of the right with the homologous bones of the left hand, assuming that they had brought bones, from some other spot, and then artificially introduced them into a mixture of volcanic tuff and plaster of Paris. Granting, however, that the high prices given for "human fossils" at Le Puy may have led to the perpetration of some frauds, it is still an interesting question to consider whether the admission of the genuineness of a single fossil, such as that now in the museum at Le Puy, would lead us to assign a higher antiquity to the existence of Man in France than is deducible from many other facts explained in the last seven chapters. In reference to this point, I may observe that although I was not able to fix with precision the exact bed in the volcanic mountain from which the rock containing the human bones was taken, M. Felix Robert has, nevertheless, after studying "the volcanic alluviums" of Denise, ascertained that, on the side of Cheyrac and the village of Malouteyre, blocks of tuff frequently occur exactly like the one in the museum. That tuff he considers a product of the latest eruption of the volcano. In it have been found the remains of Hyaena spelaea and Hippopotamus major. The eruptions of steam and gaseous matter which burst forth from the crater of Denise broke through laminated Tertiary clays, small pieces of which, some of them scarcely altered, others half converted into scoriae, were cast out in abundance, while other portions must have been in a state of argillaceous mud. Showers of such materials would be styled by the Neapolitans "aqueous lava" or "lava d'aqua," and we may well suppose that some human individuals, if any existed, would, together with wild animals, be occasionally overwhelmed in these tuffs. From near the place on the mountain whence the block with human bones now in the museum is said to have come, a stream of lava, well marked by its tabular structure, flowed down the flanks of the hill, within a few feet of the alluvial plain of the Borne, a small tributary of the Loire, on the opposite bank of which stands the town of Le Puy. Its continuous extension to so low a level clearly shows that the valley had already been deepened to within a few feet of its present depth at the time of the flowing of the lava. We know that the alluvium of the same district, having a similar relation to the present geographical outline of the valleys, is of Pleistocene date, for it contains around Le Puy the bones of Elephas primigenius and Rhinoceros tichorhinus; and this affords us a palaeontological test of the age of the human skeleton of Denise, if the latter be assumed to be coeval with the lava stream above referred to. It is important to dwell on this point, because some geologists have felt disinclined to believe in the genuineness of the "fossil man of Denise," on the ground that, if conceded, it would imply that the human race was contemporary with an older fauna, or that of the Elephas meridionalis. Such a fauna is found fossil in another layer of tuff covering the slope of Denise, opposite to that where the museum specimen was exhumed. The quadrupeds obtained from that more ancient tuff comprise Elephas meridionalis, Hippopotamus major, Rhinoceros megarhinus, Antilope torticornis, Hyaena brevirostris, and twelve others of the genera horse, ox, stag, goat, tiger, etc., all supposed to be of extinct species. This tuff, found between Malouteyre and Polignac, M. Robert regards as the product of a much older eruption, and referable to the neighbouring Montagne de St. Anne, a volcano in a much more wasted and denuded state than Denise, and classed by M. Bertrand de Doue as of intermediate age between the ancient and modern cones of Velay. The fauna to which Elephas meridionalis and its associates belong, can be shown to be of anterior date, in the north of France, to the flint implements of St. Acheul, by the following train of reasoning. The valley of the Seine is not only geographically contiguous to the valley of the Somme, but its ancient alluvium contains the same mammoth and other fossil species. The Eure, one of the tributaries of the Seine, in its way to join that river, flows in a valley which follows a line of fault in the Chalk; and this valley is seen to be comparatively modern, because it intersects at St. Prest, 4 miles below Chartres, an older valley belonging to an anterior system of drainage, which has been filled by a more ancient fluviatile alluvium, consisting of sand and gravel, 90 feet thick. I have examined the site of this older drift, and the fossils have been determined by Dr. Falconer. They comprise Elephas meridionalis, a species of rhinoceros (not R. tichorhinus), and other mammalia differing from those of the implement-bearing gravels of the Seine and Somme. The latter, belonging to the period of the mammoth, might very well have been contemporary with the modern volcanic eruptions of Central France; and we may presume, even without the aid of the Denise fossil, that Man may have witnessed these. But the tuffs and gravels in which the Elephas meridionalis are embedded were synchronous with an older epoch of volcanic action, to which the cone of St. Anne, near Le Puy, and many other mountains of M. Bertrand de Doue's middle period belong, having cones and craters, which have undergone much waste by aqueous erosion. We have as yet no proof that Man witnessed the origin of these hills of lava and scoriae of the middle phase of volcanic action. Some surprise was expressed in 1856, by several of the assembled naturalists at Le Puy, that the skull of the "fossil man of Denise," although contemporary with the mammoth, and coeval with the last eruptions of the Le Puy volcanoes [18], should be of the ordinary Caucasian or European type; but the observations of Professor Huxley on the Engis skull, cited in the fifth chapter, showing the near approach of that ancient cranium to the European standard, will help to remove this source of perplexity. HUMAN FOSSIL OF NATCHEZ ON THE MISSISSIPPI. I have already alluded to Dr. Dowler's attempt to calculate, in years, the antiquity of the human skeleton said to have been buried under four cypress forests in the delta of the Mississippi, near New Orleans (see above, Chapter 3). In that case no remains of extinct animals were found associated with those of Man: but in another part of the basin of the Mississippi, a human bone, accompanied by bones of Mastodon and Megalonyx, is supposed to have been washed out of a more ancient alluvial deposit. After visiting the spot in 1846, I described the geological position of the bones, and discussed their probable age, with a stronger bias, I must confess, as to the antecedent improbability of the contemporaneous entombment of Man and the mastodon than any geologist would now be justified in entertaining. [Illustration: Figure 26. Alluvial Plain of the Mississippi] (FIGURE 26. SECTION THROUGH THE ALLUVIAL PLAIN OF THE MISSISSIPPI. 1. Modern alluvium of the Mississippi. 2. Loam or loess. 3. f. Eocene. 4. Cretaceous.) In the latitude of Vicksburg, 32 degrees 50 minutes north, the broad, flat, alluvial plain of the Mississippi, a b, Figure 26, is bounded on its eastern side by a table-land d e, about 200 feet higher than the river, and extending 12 miles eastward with a gentle upward slope. This elevated platform ends abruptly at d, in a line of perpendicular cliffs or bluffs, the base of which is continually undermined by the great river. The table-land d-e consists at Vicksburg, through which the annexed section, Figure 26, passes, of loam, overlying the Tertiary strata f-f. Between the loam and the Tertiary formation there is usually a deposit of stratified sand and gravel, containing large fragments of silicified corals and the wreck of older Palaeozoic rocks. The age of this underlying drift, which is 140 feet thick at Natchez, has not yet been determined; but it may possibly belong to the glacial period. Natchez is about 80 miles in a straight line south of Vicksburg, on the same left bank of the Mississippi. Here there is a bluff, the upper 60 feet of which consists of a continuous portion of the same calcareous loam as at Vicksburg, equally resembling the Rhenish loess in mineral character and in being sometimes barren of fossils, sometimes so full of them that bleached land-shells stand out conspicuously in relief in the vertical and weathered face of cliffs which form the banks of streams, everywhere intersecting the loam. So numerous are the shells that I was able to collect at Natchez, in a few hours, in 1846, no less than twenty species of the genera Helix, Helicina, Pupa, Cyclostoma, Achatina, and Succinea, all identical with shells now living in the same country; and in one place I observed (as happens also occasionally in the valley of the Rhine) a passage of the loam with land-shells into an underlying marly deposit of subaqueous origin, in which shells of the genera Limnaea, Planorbis, Paludina, Physa, and Cyclas were embedded, also consisting of recent American species. Such deposits, more distinctly stratified than the loam containing land-shells, are produced, as before stated, in all great alluvial plains, where the river shifts its position, and where marshes, ponds, and lakes are formed in its old deserted channels. In this part of America, however, it may have happened that some of these lakes were caused by partial subsidences, such as were witnessed, during the earthquakes of 1811-12, around New Madrid, in the valley of the Mississippi. Owing to the destructible nature of the yellow loam, d e, Figure 26, every streamlet flowing over the platform has cut for itself, in its way to the Mississippi, a deep gully or ravine; and this erosion has of late years, especially since 1812, proceeded with accelerated speed, ascribable in some degree to the partial clearing of the native forest, but partly also to the effects of the earthquake of 1811-12. By that convulsion the region around Natchez was rudely shaken and much fissured. One of the narrow valleys near Natchez, due to this fissuring, is now called the Mammoth Ravine. Though no less than 7 miles long, and in some parts 60 feet deep, I was assured by a resident proprietor, Colonel Wiley, that it had no existence before 1812. With its numerous ramifications, it is said to have been entirely formed since the earthquake at New Madrid. Before that event, Colonel Wiley had ploughed some of the land exactly over a spot now traversed by part of this water-course. I satisfied myself that the ravine had been considerably enlarged and lengthened a short time before my visit, and it was then freshly undermined and undergoing constant waste. From a clayey deposit immediately below the yellow loam, bones of the Mastodon ohioticus, a species of Megalonyx, bones of the genera Equus, Bos, and others, some of extinct and others presumed to be of living species, had been detached, and had fallen to the base of the cliffs. Mingled with the rest, the pelvic bone of a man, os innominatum, was obtained by Dr. Dickeson of Natchez, in whose collection I saw it. It appeared to be quite in the same state of preservation, and was of the same black colour as the other fossils, and was believed to have come like them from a depth of about 30 feet from the surface. In my "Second Visit to America," in 1846, I suggested, as a possible explanation of this association of a human bone with remains of Mastodon and Megalonyx, that the former may possibly have been derived from the vegetable soil at the top of the cliff, whereas the remains of extinct mammalia were dislodged from a lower position, and both may have fallen into the same heap or talus at the bottom of the ravine. The pelvic bone might, I conceived, have acquired its black colour by having lain for years or centuries in a dark superficial peaty soil, common in that region. I was informed that there were many human bones, in old Indian graves in the same district, stained of as black a dye. On suggesting this hypothesis to Colonel Wiley of Natchez, I found that the same idea had already occurred to his mind. No doubt, had the pelvic bone belonged to any recent mammifer other than Man, such a theory would never have been resorted to; but so long as we have only one isolated case, and are without the testimony of a geologist who was present to behold the bone when still engaged in the matrix, and to extract it with his own hands, it is allowable to suspend our judgment as to the high antiquity of the fossil. If, however, I am asked whether I consider the Natchez loam, with land-shells and the bones of Mastodon and Megalonyx, to be more ancient than the alluvium of the Somme containing flint implements and the remains of the mammoth and hyaena, I must declare that I do not. Both in Europe and America the land and freshwater shells accompanying the extinct pachyderms are of living species, and I could detect no shell in the Natchez loam so foreign to the basin of the Mississippi as is the Cyrena fluminalis to the rivers of modern Europe. If, therefore, the relative ages of the Picardy and Natchez alluvium were to be decided on conchological data alone, the fluvio-marine beds of Abbeville might rank as a shade older than the loess of Natchez. My reluctance in 1846 to regard the fossil human bone as of Pleistocene date arose in part from the reflection that the ancient loess of Natchez is anterior in time to the whole modern delta of the Mississippi. The table-land, d e, Figure 26, was, I believe, once a part of the original alluvial plain or delta of the great river before it was upraised. It has now risen more than 200 feet above its pristine level. After the upheaval, or during it, the Mississippi cut through the old fluviatile formation of which its bluffs are now formed, just as the Rhine has in many parts of its valley excavated a passage through the ancient loess. If I was right in calculating that the present delta of the Mississippi must have required many tens of thousands of years for its growth, and if the claims of the Natchez man to have co-existed with the mastodon are admitted, it would follow that North America was peopled by the human race many tens of thousands of years before our time. But even were that true, we could not presume, reasoning from ascertained geological data, that the Natchez bone was anterior in date to the antique flint hatchets of St. Acheul. When we ascend the Mississippi from Natchez to Vicksburg, and then enter the Ohio, we are accompanied everywhere by a continuous fringe of terraces of sand and gravel at a certain height above the alluvial plain, first of the great river, and then of its tributary. We also find that the older alluvium contains the remains of Mastodon everywhere, and in some places, as at Evansville, those of the Megalonyx. As in the valley of the Somme in Europe, those old Pleistocene gravels often occur at more than one level, and the ancient mounds of the Ohio, with their works of art, are newer than the old terraces of the mastodon period, just as the Gallo-Roman tombs of St. Acheul or the Celtic weapons of the Abbeville peat are more modern than the tools of the mammoth-bearing alluvium. In the first place, I may remind the reader that the vertical movement of 250 feet, required to elevate the loess of Natchez to its present height, is exceeded by the upheaval which the marine stratum of Cagliari, containing pottery, has been ascertained by Count de la Marmora to have experienced. Such changes of level, therefore, have actually occurred in Europe in the human epoch, and may therefore have happened in America. In the second place, I may observe that if, since the Natchez mastodon was embedded in clay, the delta of the Mississippi has been formed, so, since the mammoth and rhinoceros of Abbeville and Amiens were enveloped in fluviatile mud and gravel, together with flint tools, a great thickness of peat has accumulated in the valley of the Somme; and antecedently to the first growth of peat, there had been time for the extinction of a great many mammalia, requiring, perhaps, a lapse of ages many times greater than that demanded for the formation of 30 feet of peat, for since the earliest growth of the latter there has been no change in the species of mammalia in Europe. Should future researches, therefore, confirm the opinion that the Natchez man co-existed with the mastodon, it would not enhance the value of the geological evidence in favour of Man's antiquity, but merely render the delta of the Mississippi available as a chronometer, by which the lapse of Pleistocene time could be measured somewhat less vaguely than by any means of measuring which have as yet been discovered or rendered available in Europe. CHAPTER 12. -- ANTIQUITY OF MAN RELATIVELY TO THE GLACIAL PERIOD AND TO THE EXISTING FAUNA AND FLORA. Chronological Relation of the Glacial Period, and the earliest known Signs of Man's Appearance in Europe. Series of Tertiary Deposits in Norfolk and Suffolk immediately antecedent to the Glacial Period. Gradual Refrigeration of Climate proved by the Marine Shells of successive Groups. Marine Newer Pliocene Shells of Northern Character near Woodbridge. Section of the Norfolk Cliffs. Norwich Crag. Forest Bed and Fluvio-marine Strata. Fossil Plants and Mammalia of the same. Overlying Boulder Clay and Contorted Drift. Newer freshwater Formation of Mundesley compared to that of Hoxne. Great Oscillations of Level implied by the Series of Strata in the Norfolk Cliffs. Earliest known Date of Man long subsequent to the existing Fauna and Flora. Frequent allusions have been made in the preceding pages to a period called the glacial, to which no reference is made in the Chronological Table of Formations given above (Chapter 1). It comprises a long series of ages, during which the power of cold, whether exerted by glaciers on the land, or by floating ice on the sea, was greater in the northern hemisphere, and extended to more southern latitudes than now. [19] It often happens that when in any given region we have pushed back our geological investigations as far as we can in search of evidence of the first appearance of Man in Europe, we are stopped by arriving at what is called the "boulder clay" or "northern drift." This formation is usually quite destitute of organic remains, so that the thread of our inquiry into the history of the animate creation, as well as of man, is abruptly cut short. The interruption, however, is by no means encountered at the same point of time in every district. In the case of the Danish peat, for example, we get no farther back than the Recent period of our Chronologic Table, and then meet with the boulder clay; and it is the same in the valley of the Clyde, where the marine strata contain the ancient canoes before described (Chapter 3), and where nothing intervenes between that Recent formation and the glacial drift. But we have seen that, in the neighbourhood of Bedford the memorials of Man can be traced much farther back into the past, namely, into the Pleistocene epoch, when the human race was contemporary with the mammoth and many other species of mammalia now extinct. Nevertheless, in Bedfordshire as in Denmark, the formation next antecedent in date to that containing the human implements is still a member of the glacial drift, with its erratic blocks. If the reader remembers what was stated in the eighth chapter as to the absence or extreme scarcity of human bones and works of art in all strata, whether marine or freshwater, even in those formed in the immediate proximity of land inhabited by millions of human beings, he will be prepared for the general dearth of human memorials in glacial formations, whether Recent, Pleistocene, or of more ancient date. If there were a few wanderers over lands covered with glaciers, or over seas infested with ice-bergs, and if a few of them left their bones or weapons in moraines or in marine drift, the chances, after the lapse of thousands of years, of a geologist meeting with one of them must be infinitesimally small. It is natural, therefore, to encounter a gap in the regular sequence of geological monuments bearing on the past history of Man, wherever we have proofs of glacial action having prevailed with intensity, as it has done over large parts of Europe and North America, in the Pleistocene period. As we advance into more southern latitudes approaching the 50th parallel of latitude in Europe, and the 40th in North America, this disturbing cause ceases to oppose a bar to our inquiries; but even then, in consequence of the fragmentary nature of all geological annals, our progress is inevitably slow in constructing anything like a connected chain of history, which can only be effected by bringing the links of the chain found in one area to supply the information which is wanting in another. The least interrupted series of consecutive documents to which we can refer in the British Islands, when we desire to connect the Pliocene with the Pleistocene periods, are found in the counties of Norfolk, Suffolk, and Essex; and I shall speak of them in this chapter, as they have a direct bearing on the relations of the human and glacial periods, which will be the subject of several of the following chapters. The fossil shells of the deposits in question clearly point to a gradual refrigeration of climate, from a temperature somewhat warmer than that now prevailing in our latitudes to one of intense cold; and the successive steps which have marked the coming on of the increasing cold are matters of no small geological interest. [20] It will be seen in the Chronological Table, that next before the Pleistocene period stands the Pliocene. The shelly and sandy beds representing these periods in Norfolk and Suffolk are termed provincially Crag, having under the name been long used in agriculture to fertilise soils deficient in calcareous matter, or to render them less stiff and impervious. In Suffolk, the older Pliocene strata called Crag are divisible into the Coralline and the Red Crags, the former being the older of the two. In Norfolk, a more modern formation, commonly termed the "Norwich," or sometimes the "mammaliferous" Crag, which is referable to the newer Pliocene period, occupies large areas. We are indebted to Mr. Searles Wood, F.G.S., for an admirable monograph on the fossil shells of these British Pliocene formations. He has not himself given us an analysis of the results of his treatise, but the following tables have been drawn up for me by Mr. S.P. Woodward, the well-known author of the "Manual of Mollusca, Recent and Fossil" (London 1851-56), in order to illustrate some of the general conclusions to which Mr. Wood's careful examination of 442 species of mollusca has led. TABLE 12/1. NUMBER OF KNOWN SPECIES OF MARINE TESTACEA IN THE THREE ENGLISH PLIOCENE DEPOSITS, CALLED THE NORWICH, THE RED, AND THE CORALLINE CRAGS. COLUMN 1: NAME. COLUMN 2: NUMBER. Brachiopoda: 6. Lamellibranchia: 206. Gasteropoda: 230. TOTAL: 442. TABLE 12/2. DISTRIBUTION OF THE ABOVE MARINE TESTACEA. COLUMN 1: NAME. COLUMN 2: NUMBER. Norwich Crag: 81. Red Crag: 225. Coralline Crag: 327. Species common to the Norwich and Red Crag (not in Coralline): 33. Species common to the Norwich and Coralline (not in Red): 4. Species common to the Red and Coralline (not in Norwich): 116. Species common to the Norwich, Red, and Coralline: 19.* (* These 19 species must be added to the numbers 33, 4, and 116 respectively, in order to obtain the full amount of common species in each of those cases.) TABLE 12/3. PROPORTION OF RECENT TO EXTINCT SPECIES. COLUMN 1: NAME. COLUMN 2: NUMBER OF RECENT. COLUMN 3: NUMBER OF EXTINCT. COLUMN 4: PERCENTAGE OF RECENT. Norwich Crag: 69: 12: 85%. Red Crag: 130: 95: 57%. Coralline Crag: 168: 159: 51%. TABLE 12/4. RECENT SPECIES NOT LIVING NOW IN BRITISH SEAS. COLUMN 1: NAME. COLUMN 2: NUMBER OF NORTHERN. COLUMN 3: NUMBER OF SOUTHERN. Norwich Crag: 12: 0. Red Crag: 8: 16. Coralline Crag: 2: 27. In the above list I have not included the shells of the glacial beds of the Clyde and of several other British deposits of newer origin than the Norwich Crag, in which nearly all--perhaps all--the species are Recent. The land and freshwater shells, thirty-two in number, have also been purposely omitted, as well as three species of London Clay shells, suspected by Mr. Wood himself to be spurious. By far the greater number of the living marine species included in these tables are still inhabitants of the British seas; but even these differ considerably in their relative abundance, some of the commonest of the Crag shells being now extremely scarce; as, for example, Buccinopsis Dalei; and others, rarely met with in a fossil state, being now very common, as Murex erinaceus and Cardium echinatum. The last table throws light on a marked alteration in the climate of the three successive periods. It will be seen that in the Coralline Crag there are twenty-seven southern shells, including twenty-six Mediterranean, and one West Indian species (Erato Maugeriae). Of these only thirteen occur in the Red Crag, associated with three new southern species, while the whole of them disappear from the Norwich beds. On the other hand, the Coralline Crag contains only two shells closely related to arctic forms of the genera Admete and Limopsis. The Red Crag contains, as stated in the table, eight northern species, all of which recur in the Norwich Crag, with the addition of four others, also inhabitants of the arctic regions; so that there is good evidence of a continual refrigeration of climate during the Pliocene period in Britain. The presence of these northern shells cannot be explained away by supposing that they were inhabitants of the deep parts of the sea; for some of them, such as Tellina calcarea and Astarte borealis, occur plentifully, and sometimes, with the valves united by their ligament, in company with other littoral shells, such as Mya arenaria and Littorina rudis, and evidently not thrown up from deep water. Yet the northern character of the Norwich Crag is not fully shown by simply saying that it contains twelve northern species. It is the predominance of certain genera and species, such as Tellina calcarea, Astarte borealis, Scalaria groenlandica, and Fusus carinatus, which satisfies the mind of a conchologist as to the arctic character of the Norwich Crag. In like manner, it is the presence of such genera as Pyrula, Columbella, Terebra, Cassidaria, Pholadomya, Lingula, Discina, and others which give a southern aspect to the Coralline Crag shells. The cold, which had gone on increasing from the time of the Coralline to that of the Norwich Crag, continued, though not perhaps without some oscillations of temperature, to become more and more severe after the accumulation of the Norwich Crag, until it reached its maximum in what has been called the glacial epoch. The marine fauna of this last period contains, both in Ireland and Scotland, Recent species of mollusca now living in Greenland and other seas far north of the areas where we find their remains in a fossil state. The refrigeration of climate from the time of the older to that of the newer Pliocene strata is not now announced for the first time, as it was inferred from a study of the Crag shells in 1846 by the late Edward Forbes.* (* "Memoirs of the Geological Survey" London 1846 page 391.) The most southern point to which the marine beds of the Norwich Crag have yet been traced is at Chillesford, near Woodbridge, in Suffolk, about 80 miles north-east of London, where, as Messrs. Prestwich and Searles Wood have pointed out,* they exhibit decided marks of having been deposited in a sea of a much lower temperature than that now prevailing in the same latitude. (* "Quarterly Journal of the Geological Society" volume 5 1849 page 345.) Out of twenty-three shells obtained in that locality from argillaceous strata 20 feet thick, two only, namely, Nucula Cobboldiae and Tellina obliqua, are extinct, and not a few of the other species, such as Leda lanceolata, Cardium groenlandicum, Lucina borealis, Cyprina islandica, Panopaea norvegica, and Mya truncata, betray a northern, and some of them an arctic character. These Chillesford beds are supposed to be somewhat more modern than any of the purely marine strata of the Norwich Crag exhibited by the sections of the Norfolk cliffs north-west of Cromer, which I am about to describe. Yet they probably preceded in date the "Forest Bed" and fluvio-marine deposits of those same cliffs. They are, therefore, of no small importance in reference to the chronology of the glacial period, since they afford evidence of an assemblage of fossil shells with a proportion of between eight and nine in a hundred of extinct species occurring so far south as latitude 53 degrees north, and indicating so cold a climate as to imply that the glacial period commenced before the close of the Pliocene era. [Illustration: Figure 27. Succession of Strata] (FIGURE 27. DIAGRAM TO ILLUSTRATE THE GENERAL SUCCESSION OF THE STRATA IN THE NORFOLK CLIFFS, EXTENDING SEVERAL MILES NORTH-WEST AND SOUTH-EAST OF CROMER. A. Site of Cromer Jetty. 1. Upper Chalk with flints in regular stratification. 2. Norwich Crag, rising from low water at Cromer to the top of the cliffs at Weybourn, seven miles distant. 3. "Forest Bed," with stumps of trees in situ and remains of Elephas meridionalis, E. primigenius, E. antiquus, Rhinoceros etruscus, etc. This bed increases in depth and thickness eastward. No Crag (Number 2) known east of Cromer Jetty. 3 prime. Fluvio-marine series. At Cromer and eastward, with abundant lignite beds and mammalian remains, and with cones of the Scotch and spruce firs and wood. At Runton, north-west of Cromer, expanding into a thick freshwater deposit, with overlying marine strata, elsewhere consisting of alternating sands and clays, tranquilly deposited, some with marine, others with freshwater shells. 4. Boulder clay of glacial period, with far transported erratics, some of them polished and scratched, 20 to 80 feet in thickness. 5. Contorted drift. 6. Superficial gravel and sand with covering of vegetable soil.) The annexed section (Figure 27) will give a general idea of the ordinary succession of the Pliocene and Pleistocene strata which rest upon the Chalk in the Norfolk and Suffolk cliffs. These cliffs vary in height from fifty to above three hundred feet. At the north-western extremity of the section at Weybourn (beyond the limits of the annexed diagram), and from thence to Cromer, a distance of 7 miles, the Norwich Crag, a marine deposit, reposes immediately upon the Chalk. A vast majority of its shells are of living species such as Cardium edule, Cyprina islandica, Scalaria groenlandica, and Fusus antiquus, and some few extinct, as Tellina obliqua, and Nucula Cobboldiae. At Cromer jetty this formation thins out, as expressed in the diagram at A; and to the south we find Number 3, or what is commonly called the "Forest Bed," reposing immediately upon the Chalk, and occupying, as it were, the place previously held by the marine Crag Number 2. This buried forest has been traced for more than 40 miles, being exposed at certain seasons and states of the beach between high and low water mark. It extends from Cromer to near Kessingland, and consists of the stumps of numerous trees standing erect, with their roots attached to them, and penetrating in all directions into the loam or ancient vegetable soil on which they grew. They mark the site of a forest which existed there for a long time, since, besides the erect trunks of trees, some of them 2 and 3 feet in diameter, there is a vast accumulation of vegetable matter in the immediately overlying clays. Thirty years ago, when I first examined this bed, I saw many trees, with their roots in the old soil, laid open at the base of the cliff near Happisburgh; and long before my visit, other observers, and among them the late Mr. J.C. Taylor, had noticed the buried forest. Of late years it has been repeatedly seen at many points by Mr. Gunn, and, after the great storms of the autumn of 1861, by Mr. King. In order to expose the stumps to view, a vast body of sand and shingle must be cleared away by the force of the waves. [21] As the sea is always gaining on the land, new sets of trees are brought to light from time to time, so that the breadth as well as length of the area of ancient forest land seems to have been considerable. Next above Number 3, we find a series of sands and clays with lignite (Number 3 prime), sometimes 10 feet thick, and containing alternations of fluviatile and marine strata, implying that the old forest land, which may at first have been considerably elevated above the level of the sea, had sunk down so as to be occasionally overflowed by a river, and at other times by the salt waters of an estuary. There were probably several oscillations of level which assisted in bringing about these changes, during which trees were often uprooted and laid prostrate, giving rise to layers of lignite. Occasionally marshes were formed and peaty matter accumulated, after which salt water again predominated, so that species of Mytilus, Mya, Leda, and other marine genera, lived in the same area where the Unio, Cyclas, and Paludina had flourished for a time. That the marine shells lived and died on the spot, and were not thrown up by the waves during a storm, is proved, as Mr. King has remarked, by the fact that at West Runton, north-west of Cromer, the Mya truncata and Leda myalis are found with both valves united and erect in the loam, all with their posterior or siphuncular extremities uppermost. This attitude affords as good evidence to the conchologist that those mollusca lived and died on the spot as the upright position of the trees proves to the botanist that there was a forest over the Chalk east of Cromer. Between the stumps of the buried forest, and in the lignite above them, are many well-preserved cones of the Scotch and spruce firs, Pinus sylvestris, and Pinus abies. The specific names of these fossils were determined for me in 1840, by a botanist of no less authority than the late Robert Brown; and Professor Heer has lately examined a large collection from the same stratum, and recognised among the cones of the spruce some which had only the central part or axis remaining, the rest having been bitten off, precisely in the same manner as when in our woods the squirrel has been feeding on the seeds. There is also in the forest-bed a great quantity of resin in lumps, resembling that gathered for use, according to Professor Heer, in Switzerland, from beneath spruce firs. The following is a list of some of the plants and seeds which were collected by the Reverend S.W. King, in 1861, from the forest bed at Happisburgh, and named by Professor Heer:-- PLANTS AND SEEDS OF THE FOREST AND LIGNITE BEDS BELOW THE GLACIAL DRIFT OF THE NORFOLK CLIFFS. Pinus sylvestris, Scotch fir. Pinus abies, spruce fir. Taxus baccata, yew. Nuphar luteum, yellow water-lily. Ceratophyllum demersum, hornwort. Potamogeton, pondweed. Prunus spinosus, common sloe. Menyanthes trifoliata, buckbean. Nymphaea alba, white water-lily. Alnus, alder. Quercus, oak. Betula, birch. The insects, so far as they are known, including several species of Donacia, are, like the plants and freshwater shells, of living species. It may be remarked, however, that the Scotch fir has been confined in historical times to the northern parts of the British Isles, and the spruce fir is nowhere indigenous in Great Britain. The other plants are such as might now be found in Norfolk, and many of them indicate fenny or marshy ground.* (* Mr. King discovered in 1863, in the forest bed, several rhizomes of the large British fern Osmunda regalis, of such dimensions as they are known to attain in marshy places. They are distinguishable from those of other British ferns by the peculiar arrangement of the vessels, as seen under the microscope in a cross section.) When we consider the familiar aspect of the flora, the accompanying mammalia are certainly most extraordinary. There are no less than three elephants, a rhinoceros and hippopotamus, a large extinct beaver, and several large estuarine and marine mammalia, such as the walrus, the narwhal, and the whale. The following is a list of some of the species of which the bones have been collected by Messrs. Gunn and King. Those marked (asterisk) have been recorded by Professor Owen in his British Fossil Mammalia. Those marked (dagger) have been recognised by the same authority in the cabinets of Messrs. Gunn and King, or in the Norwich Museum; the other three are given on the authority of Dr. Falconer. MAMMALIA OF THE FOREST AND LIGNITE BEDS BELOW THE GLACIAL DRIFT OF THE NORFOLK CLIFFS. Elephas meridionalis. (asterisk) Elephas primigenius. Elephas antiquus. Rhinoceros etruscus. (asterisk) Hippopotamus (major?). (asterisk) Sus scrofa. (asterisk) Equus (fossilis?). (asterisk) Ursus (sp.?). (dagger) Canis lupus. (dagger) Bison priscus. (dagger) Megaceros hibernicus. (asterisk) Cervus capreolus. (dagger) Cervus tarandus. (dagger) Cervus Sedgwickii. (asterisk) Arvicola amphibia. (asterisk) Castor (Trogontherium) Cuvieri. (asterisk) Castor europaeus. (asterisk) Palaeospalax magnus. (dagger) Trichecus rosmarus, Walrus. (dagger) Monodon monoceros, Narwhal. (dagger) Balaenoptera. Mr. Gunn informs me that the vertebrae of two distinct whales were found in the fluvio-marine beds at Bacton, and that one of them, shown to Professor Owen, is said by him to imply that the animal was 60 feet long. A narwhal's tusk was discovered by Mr. King near Cromer, and the remains of a walrus. No less than three species of elephant, as determined by Dr. Falconer, have been obtained from the strata 3 and 3 prime, of which, according to Mr. King, E. meridionalis is the most common, the mammoth next in abundance, and the third, E. antiquus, comparatively rare. The freshwater shells accompanying the fossil quadrupeds, above enumerated, are such as now inhabit rivers and ponds in England; but among them, as at Runton, between the "forest bed" and the glacial deposits, a remarkable variety of the Cyclas amnica occurs (Figure 28), identical with that which accompanies the Elephas antiquus at Ilford and Grays in the valley of the Thames. All the freshwater shells of the beds intervening between the Forest-bed Number 3, and the glacial formation 4, Figure 27, are of Recent species. As to the small number of marine shells occurring in the same fluvio-marine series, I have seen none which belonged to extinct species, although one or two have been cited by authors. I am in doubt, therefore, whether to class the forest bed and overlying strata as Pleistocene, or to consider them as beds of passage between the Pliocene and Pleistocene periods. The fluvio-marine series usually terminates upwards in finely laminated sands and clays without fossils, on which reposes the boulder clay. [Illustration: Figure 28. Cyclas] (FIGURE 28. Cyclas (Pisidium) amnica var.? The two middle figures are of the natural size.) This formation, Number 4, is of very varying thickness. Its glacial character is shown, not only by the absence of stratification, and the great size and angularity of some of the included blocks of distant origin, but also by the polished and scratched surfaces of such of them as are hard enough to retain any markings. Near Cromer, blocks of granite from 6 to 8 feet in diameter have been met with, and smaller ones of syenite, porphyry, and trap, besides the wreck of the London Clay, Chalk, Oolite, and Lias, mixed with more ancient fossiliferous rocks. Erratics of Scandinavian origin occur chiefly in the lower portions of the till. I came to the conclusion in 1834, that they had really come from Norway and Sweden, after having in that year traced the course of a continuous stream of such blocks from those countries to Denmark, and across the Elbe, through Westphalia, to the borders of Holland. It is not surprising that they should then reappear on our eastern coast between the Tweed and the Thames, regions not half so remote from parts of Norway as are many Russian erratics from the sources whence they came. [22] [Illustration: Figure 29. Cliff] (FIGURE 29. CLIFF 50 FEET HIGH BETWEEN BACTON GAP AND MUNDESLEY. Section through Gravel (top), Sand, Loam and Till (bottom).) According to the observations of the Reverend J. Gunn and the late Mr. Trimmer, the glacial drift in the cliffs at Lowestoft consists of two divisions, the lower of which abounds in the Scandinavian blocks, supposed to have come from the north-east; while the upper, probably brought by a current from the north-west, contains chiefly fragments of Oolitic rocks, more rolled than those of the lower deposit. The united thickness of the two divisions, without reckoning some interposed laminated beds, is 80 feet, but it probably exceeds 100 feet near Happisburgh.* (* "Quarterly Journal of the Geological Society" volume 7 1851 page 21.) Although these subdivisions of the drift may be only of local importance, they help to show the changes of currents and other conditions, and the great lapse of time which the accumulation of so varied a series of deposits must have required. The lowest part of the glacial till, resting on the laminated clays before mentioned, is very even and regular, while its upper surface is remarkable for the unevenness of its outline, owing partly, in all likelihood, to denudation, but still more to other causes presently to be discussed. The overlying strata of sand and gravel, Number 5, Figure 27, often display a most singular derangement in their stratification, which in many places seems to have a very intimate relation to the irregularities of outline in the subjacent till. There are some cases, however, where the upper strata are much bent, while the lower beds of the same series have continued horizontal. Thus the annexed section (Figure 29) represents a cliff about 50 feet high, at the bottom of which is till, or unstratified clay, containing boulders, having an even horizontal surface, on which repose conformably beds of laminated clay and sand about 5 feet thick, which, in their turn, are succeeded by vertical, bent, and contorted layers of sand and loam 20 feet thick, the whole being covered by flint gravel. The curves of the variously coloured beds of loose sand, loam, and pebbles, are so complicated that not only may we sometimes find portions of them which maintain their verticality to a height of 10 or 15 feet, but they have also been folded upon themselves in such a manner that continuous layers might be thrice pierced in one perpendicular boring. [Illustration: Figures 30 and 31. Strata] (FIGURE 30. FOLDING OF THE STRATA BETWEEN EAST AND WEST RUNTON.) (FIGURE 31. SECTION OF CONCENTRIC BEDS WEST OF CROMER. 1. Blue clay. 2. White sand. 3. Yellow Sand. 4. Striped loam and clay. 5. Laminated blue clay.) At some points there is an apparent folding of the beds round a central nucleus, as at a, Figure 30, where the strata seem bent round a small mass of Chalk, or, as in Figure 31, where the blue clay Number 1 is in the centre; and where the other strata 2, 3, 4, 5 are coiled round it; the entire mass being 20 feet in perpendicular height. This appearance of concentric arrangement around a nucleus is, nevertheless, delusive, being produced by the intersection of beds bent into a convex shape; and that which seems the nucleus being, in fact, the innermost bed of the series, which has become partially visible by the removal of the protuberant portions of the outer layers. To the north of Cromer are other fine illustrations of contorted drift reposing on a floor of Chalk horizontally stratified and having a level surface. These phenomena, in themselves sufficiently difficult of explanation, are rendered still more anomalous by the occasional enclosure in the drift of huge fragments of Chalk many yards in diameter. One striking instance occurs west of Sheringham, where an enormous pinnacle of Chalk, between 70 and 80 feet in height, is flanked on both sides by vertical layers of loam, clay, and gravel (Figure 32). [Illustration: Figure 32. Pinnacle of Chalk] (FIGURE 32. INCLUDED PINNACLE OF CHALK AT OLD HYTHE POINT, WEST OF SHERINGHAM. d. Chalk with regular layers of flints. c. Layer called "the pan," of Chalk, flints, and marine shells of Recent species, cemented by oxide of iron.) This chalky fragment is only one of many detached masses which have been included in the drift, and forced along with it into their present position. The level surface of the Chalk in situ (d) may be traced for miles along the coast, where it has escaped the violent movements to which the incumbent drift has been exposed.* (* For a full account of the drift of East Norfolk, see a paper by the author, "Philosophical Magazine" Number 104 May 1840.) We are called upon, then, to explain how any force can have been exerted against the upper masses, so as to produce movements in which the subjacent strata have not participated. It may be answered that, if we conceive the till and its boulders to have been drifted to their present place by ice, the lateral pressure may have been supplied by the stranding of ice-islands. We learn, from the observations of Messrs. Dease and Simpson in the polar regions, that such islands, when they run aground, push before them large mounds of shingle and sand. It is therefore probable that they often cause great alterations in the arrangement of pliant and incoherent strata forming the upper part of shoals or submerged banks, the inferior portions of the same remaining unmoved. Or many of the complicated curvatures of these layers of loose sand and gravel may have been due to another cause, the melting on the spot of ice-bergs and coast ice in which successive deposits of pebbles, sand, ice, snow, and mud, together with huge masses of rock fallen from cliffs, may have become interstratified. Ice-islands so constituted often capsize when afloat, and gravel once horizontal may have assumed, before the associated ice was melted, an inclined or vertical position. The packing of ice forced up on a coast may lead to a similar derangement in a frozen conglomerate of sand or shingle, and, as Mr. Trimmer has suggested,* alternate layers of earthy matter may have sunk down slowly during the liquefaction of the intercalated ice so as to assume the most fantastic and anomalous positions, while the strata below, and those afterwards thrown down above, may be perfectly horizontal (see above). (* "Quarterly Journal of the Geological Society" volume 7 1851 pages 22, 30.) In most cases where the principal contortions of the layers of gravel and sand have a decided correspondence with deep indentations in the underlying till, the hypothesis of the melting of large lumps and masses of ice once mixed up with the till affords the most natural explanation of the phenomena. The quantity of ice now seen in the cliffs near Behring's Straits, in which the remains of fossil elephants are common, and the huge fragments of solid ice which Meyendorf discovered in Siberia, after piercing through a considerable thickness of incumbent soil, free from ice, is in favour of such an hypothesis, the partial failure of support necessarily giving rise to foldings in the overlying and previously horizontal layers, as in the case of creeps in coal mines.* (* See "Manual of Geology" by the author, page 51.) In the diagram of the cliffs at page 167, the bent and contorted beds Number 5, last alluded to, are represented as covered by undisturbed beds of gravel and sand Number 6. These are usually destitute of organic remains; but at some points marine shells of Recent species are said to have been found in them. They afford evidence at many points of repeated denudation and redeposition, and may be the monuments of a long series of ages. MUNDESLEY POST-GLACIAL FRESHWATER FORMATION. In the range of cliffs above described at Mundesley, about 8 miles south-east of Cromer, a fine example is seen of a freshwater formation, newer than all those already mentioned, a deposit which has filled up a depression hollowed out of all the older beds 3, 4, and 5 of the section Figure 27. [Illustration: Figure 33. Newer Freshwater Formation] (FIGURE 33. SECTION OF THE NEWER FRESHWATER FORMATION I N THE CLIFFS AT MUNDESLEY, EIGHT MILES SOUTH-EAST OF CROMER, DRAWN UP BY THE REVEREND S.W. KING. Height of cliff where lowest, 35 feet above high water. OLDER SERIES. 1. Fundamental Chalk, below the beach line. 3. Forest bed, with elephant, rhinoceros, stag, etc., and with tree roots and stumps, also below the beach line. 3 prime. Finely laminated sands and clays, with thin layer of lignite, and shells of Cyclas and Valvata, and with Mytilus in some beds. 4. Glacial boulder till. 5. Contorted drift. 6. Gravel overlying contorted drift. N.B.--Number 2 of the section, Figure 27, is wanting here. NEWER FRESHWATER BEDS. A. Coarse river gravel, with shells of Anodon, Valvata, Cyclas, Succinea, Limnaea, Paludina, etc., seeds of Ceratophyllum demersum, Nuphar lutea, scales and bones of pike, perch, salmon, etc., elytra of Donacia, Copris, Harpalus, and other beetles. C. Yellow sands. D. Drift gravel.) When I examined this line of coast in 1839, the section alluded to was not so clearly laid open to view as it has been of late years, and finding at that period not a few of the fossils in the lignite beds Number 3 prime above the forest bed, identical in species with those from the post-glacial deposits B C, I supposed the whole to have been of contemporaneous origin, and so described them in my paper on the Norfolk cliffs.* (* "Philosophical Magazine" volume 16 1840 page 345.) Mr. Gunn was the first to perceive this mistake, which he explained to me on the spot when I revisited Mundesley in the autumn of 1859 in company with Dr. Hooker and Mr. King. The last-named geologist has had the kindness to draw up for me the annexed diagram (Figure 33) of the various beds which he has recently studied in detail.* (* Mr. Prestwich has given a correct account of this section in a paper read to the British Association, Oxford, 1860. See "The Geologist" volume 4 1861.) The formations 3, 4, and 5 already described, Figure 27, were evidently once continuous, for they may be followed for miles north-west and south-east without a break, and always in the same order. A valley or river channel was cut through them, probably during the gradual upheaval of the country, and the hollow became afterwards the receptacle of the comparatively modern freshwater beds A, B, C, and D. They may well represent a silted up river-channel, which remained for a time in the state of a lake or mere, and in which the black peaty mass B accumulated by a very slow growth over the gravel of the river-bed A. In B we find remains of some of the same plants which were enumerated as common in the ancient lignite in 3 prime, such as the yellow water-lily and hornwort, together with some freshwater shells which occur in the same fluvio-marine series 3 prime. [Illustration: Figure 34. Paludina marginata] (FIGURE 34. Paludina marginata, Michaud (P. minuta, Strickland). Hydrobia marginata.* (* This shell is said to have a sub-spiral operculum (not a concentric one, as in Paludina), and therefore to be referable to the Hydrobia, a sub-genus of Rissoa. But this species is always associated with freshwater shells, while the Rissoae frequent marine and brackish waters.) The middle figure is of the natural size.) The only shell which I found not referable to a British species is the minute Paludina, Figure 34, already alluded to. When I showed the scales and teeth of the pike, perch, roach, and salmon, which I obtained from this formation, to M. Agassiz, he thought they varied so much from their nearest living representatives that they might rank as distinct species; but Mr. Yarrell doubted the propriety of so distinguishing them. The insects, like the shells and plants, are identical, so far as they are known, with living British species. No progress has yet been made at Mundesley in discovering the contemporary mammalia. By referring to the description and section before given of the freshwater deposit at Hoxne, the reader will at once perceive the striking analogy of the Mundesley and Hoxne deposits, the latter so productive of flint implements of the Amiens type. Both of them, like the Bedford gravel with flint tools and the bones of extinct mammalia, are post-glacial. It will also be seen that a long series of events, accompanied by changes in physical geography, intervened between the "forest bed," Number 3, Figure 27, when the Elephas meridionalis flourished, and the period of the Mundesley fluviatile beds A, B, C; just as in France I have shown that the same E. meridionalis belonged to a system of drainage different from and anterior to that with which the flint implements of the old alluvium of the Somme and the Seine were connected. Before the growth of the ancient forest, Number 3, Figure 33, the Mastodon arvernensis, a large proboscidian, characteristic of the Norwich Crag, appears to have died out, or to have become scarce, as no remains of it have yet been found in the Norfolk cliffs. There was, no doubt, time for other modifications in the mammalian fauna between the era of the marine beds, Number 2, Figure 27 (the shells of which imply permanent submergence beneath the sea), and the accumulation of the uppermost of the fluvio-marine, and lignite beds, Number 3 prime, which overlie both Numbers 3 and 2, or the buried forest and the Crag. In the interval we must suppose repeated oscillations of level, during which land covered with trees, an estuary with its freshwater shells, and the sea with its Mya truncata and other mollusca still retaining their erect position, gained by turns the ascendency. These changes were accompanied by some denudation followed by a grand submergence of several hundred feet, probably brought about slowly, and when floating ice aided in transporting erratic blocks from great distances. The glacial till Number 4 then originated, and the gravel and sands Number 5 were afterwards superimposed on the boulder clay, first in horizontal beds, which became subsequently contorted. These were covered in their turn by other layers of gravel and sand, Number 6, Figures 27 and 33, the downward movement still continuing. The entire thickness of the beds above the Chalk at some points near the coast, and the height at which they now are raised, are such as to show that the subsidence of the country after the growth of the forest bed exceeded 400 feet. The re-elevation must have amounted to nearly as many feet, as the site of the ancient forest, originally sub-aerial, has been brought up again to within a few feet of high-water mark. Lastly, after all these events, and probably during the final process of emergence, the valley was scooped out in which the newer freshwater strata of Mundesley, Figure 33, were gradually deposited. Throughout the whole of this succession of geographical changes, the flora and invertebrate fauna of Europe appear to have undergone no important revolution in their specific characters. The plants of the forest bed belonged already to what has been called the Germanic flora. The mollusca, the insects, and even some of the mammalia, such as the European beaver and roebuck, were the same as those now co-existing with Man. Yet the oldest memorials of our species at present discovered in Great Britain are post-glacial, or posterior in date to the boulder clay, Number 4, Figures 27 and 33. The position of the Hoxne flint implements corresponds with that of the Mundesley beds, from A to D, Figure 33, and the most likely stratum in which to find hereafter flint tools is no doubt the gravel A of that section, which has all the appearance of an old river-bed. No flint tools have yet been observed there, but had the old alluvium of Amiens or Abbeville occurred in the Norfolk cliffs instead of the valley of the Somme, and had we depended on the waves of the sea instead of the labour of many hundred workmen continued for twenty years, for exposing the flint implements to view, we might have remained ignorant to this day of the fossil relics brought to light by M. Boucher de Perthes and those who have followed up his researches. Neither need we despair of one day meeting with the signs of Man's existence in the forest bed Number 3, or in the overlying strata 3 prime, on the ground of any uncongeniality in the climate or incongruity in the state of the animate creation with the well-being of our species. For the present we must be content to wait and consider that we have made no investigations which entitle us to wonder that the bones or stone weapons of the era of the Elephas meridionalis have failed to come to light. If any such lie hid in those strata, and should hereafter be revealed to us, they would carry back the antiquity of Man to a distance of time probably more than twice as great as that which separates our era from that of the most ancient of the tool-bearing gravels yet discovered in Picardy, or elsewhere. But even then the reader will perceive that the age of Man, though pre-glacial, would be so modern in the great geological calendar, as given in Chapter 1, that he would scarcely date so far back as the commencement of the Pleistocene period. CHAPTER 13. -- CHRONOLOGICAL RELATIONS OF THE GLACIAL PERIOD AND THE EARLIEST SIGNS OF MAN'S APPEARANCE IN EUROPE. Chronological Relations of the Close of the Glacial Period and the earliest geological Signs of the Appearance of Man. Effects of Glaciers and Icebergs in polishing and scoring Rocks. Scandinavia once encrusted with Ice like Greenland. Outward Movement of Continental Ice in Greenland. Mild Climate of Greenland in the Miocene Period. Erratics of Recent Period in Sweden. Glacial State of Sweden in the Pleistocene Period. Scotland formerly encrusted with Ice. Its subsequent Submergence and Re-elevation. Latest Changes produced by Glaciers in Scotland. Remains of the Mammoth and Reindeer in Scotch Boulder Clay. Parallel Roads of Glen Roy formed in Glacier Lakes. Comparatively modern Date of these Shelves. The chronological relations of the human and glacial periods were frequently alluded to in the last chapter, and the sections obtained near Bedford, and at Hoxne, in Suffolk, and a general view of the Norfolk cliffs, have taught us that the earliest signs of Man's appearance in the British isles, hitherto detected, are of post-glacial date. We may now therefore inquire whether the peopling of Europe by the human race and by the mammoth and other mammalia now extinct, was brought about during the concluding phases of the glacial epoch. Although it may be impossible in the present state of our knowledge to come to a positive conclusion on this head, I know of no inquiry better fitted to clear up our views respecting the geological state of the northern hemisphere at the time when the fabricators of the flint implements of the Amiens type flourished. I shall therefore now proceed to consider the chronological relations of that ancient people with the final retreat of the glaciers from the mountains of Scandinavia, Scotland, Wales, and Switzerland. SUPERFICIAL MARKINGS AND DEPOSITS LEFT BY GLACIERS AND ICEBERGS. In order fully to discuss this question, I must begin by referring to some of the newest theoretical opinions entertained on the glacial question. When treating of this subject in the "Principles of Geology," chapter 15, and in the "Manual (or Elements) of Geology," chapter 11, I have stated that the whole mass of the ice in a glacier is in constant motion, and that the blocks of stone detached from boundary precipices, and the mud and sand swept down by avalanches of snow, or by rain from the surrounding heights, are lodged upon the surface and slowly borne along in lengthened mounds, called in Switzerland moraines. These accumulations of rocky fragments and detrital matter are left at the termination of the glacier, where it melts in a confused heap called the "terminal moraine," which is unstratified, because all the blocks, large and small, as well as the sand and the finest mud, are carried to equal distances and quietly deposited in a confused mass without being subjected to the sorting power of running water, which would convey the finer materials farther than the coarser ones, and would produce, as the strength of the current varied from time to time in the same place, a stratified arrangement. In those regions where glaciers reach the sea, and where large masses of ice break off and float away, moraines, such as I have just alluded to, may be transported to indefinite distances, and may be deposited on the bottom of the sea wherever the ice happens to melt. If the liquefaction take place when the berg has run aground and is stationary, and if there be no current, the heap of angular and rounded stones, mixed with sand and mud, may fall to the bottom in an unstratified form called "till" in Scotland, and which has been shown in the last chapter to abound in the Norfolk cliffs; but should the action of a current intervene at certain points or at certain seasons, then the materials will be sorted as they fall, and arranged in layers according to their relative weight and size. Hence there will be passages from till to stratified clay, gravel, and sand. Some of the blocks of stone with which the surfaces of glaciers are loaded, falling occasionally through fissures in the ice, get fixed and frozen into the bottom of the moving mass, and are pushed along under it. In this position, being subjected to great pressure, they scoop out long rectilinear furrows or grooves parallel to each other on the subjacent solid rock. Smaller scratches and striae are made on the polished surface by crystals or projecting edges of the hardest minerals, just as a diamond cuts glass. In all countries the fundamental rock on which the boulder formation reposes, if it consists of granite, gneiss, marble, or other hard stone capable of permanently retaining any superficial markings which may have been imprinted upon it, is smoothed or polished, and exhibits parallel striae and furrows having a determinate direction. This prevailing direction, both in Europe and North America, is evidently connected with the course taken by the erratic blocks in the same district, and is very commonly from north to south, or if it be twenty or thirty or more degrees to the east or west of north, still always corresponds to the direction in which the large angular and rounded stones have travelled. These stones themselves also are often furrowed and scratched on more than one side, like those already spoken of as occurring in the glacial drift of Bedford, and in that of Norfolk. When we contemplate the area which is now exposed to the abrading action of ice, or which is the receptacle of moraine matter thrown down from melting glaciers or bergs, we at once perceive that the submarine area is the most extensive of the two. The number of large icebergs which float annually to great distances in the northern and southern hemispheres is extremely great, and the quantity of stone and mud which they carry about with them enormous. Some floating islands of ice have been met with from 2 to 5 miles in length, and from 100 to 225 feet in height above water, the submerged portion, according to the weight of ice relatively to sea water, being from six to eight times more considerable than the part which is visible. Such masses, when they run aground on the bottom of the sea, must exert a prodigious mechanical power, and may polish and groove the subjacent rocks after the manner of glaciers on the land. Hence there will often be no small difficulty in distinguishing between the effects of the submarine and supramarine agency of ice. SCANDINAVIA ONCE COVERED WITH ICE, AND A CENTRE OF DISPERSION OF ERRATICS. In the north of Europe, along the borders of the Baltic, where the boulder formation is continuous for hundreds of miles east and west, it has been long known that the erratic blocks, often of very large size, are of northern origin. Some of them have come from Norway and Sweden, others from Finland, and their present distribution implies that they were carried southwards, for a part at least of their way, by floating ice, at a time when much of the area over which they are scattered was under water. But it appears from the observations of Boetlingk, in 1840, and those of more recent inquirers, that while many blocks have travelled to the south, others have been carried northwards, or to the shores of the Polar Sea, and others north-eastward, or to those of the White Sea. In fact, they have wandered towards all points of the compass, from the mountains of Scandinavia as a centre, and the rectilinear furrows imprinted by them on the polished surfaces of the mountains where the rocks are hard enough to retain such markings, radiate in all directions, or point outwards from the highest land, in a manner corresponding to the course of the erratics above mentioned.* (* Sir R.I. Murchison, in his "Russia and the Ural Mountains" (1845) has indicated on a map not only the southern limits of the Scandinavian drift, but by arrows the direction in which "it proceeded eccentrically from a common central region.") Before the glacial theory was adopted, the Swedish and Norwegian geologists speculated on a great flood, or the sudden rush of an enormous body of water charged with mud and stones, descending from the central heights or watershed into the adjoining lower lands. The erratic blocks were supposed in their downward passage to have smoothed and striated the rock surfaces over which they were forced along. It would be a waste of time, in the present state of science, to controvert this hypothesis, as it is now admitted that even if the rush of a diluvial current, invented for the occasion and wholly without analogy in the known course of nature, be granted, it would be inadequate to explain the uniformity, parallelism, persistency, and rectilinearity of the so-called glacial furrows. It is moreover ascertained that heavy masses of rock, not fixed in ice, and moving as freely as they do when simply swept along by a muddy current, do not give rise to such scratches and furrows. M. Kjerulf of Christiania, in a paper lately communicated to the Geological Society of Berlin,* has objected, and perhaps with reason, to what he considers the undue extent to which I have, in some of my writings, supposed the mountains of northern Europe, to have been submerged during the glacial period. (* "Zeitschrift der Deutschen Geologischen Gesellschaft" Berlin 1860.) He remarks that the signs of glacial action on the Scandinavian mountains ascend as high as 6000 feet, whereas fossil marine shells of the same period never reach elevations exceeding 600 feet. The land, he says, may have been much higher than it now is, but it has evidently not been much lower since the commencement of the glacial period, or marine shells would be traceable to more elevated points. In regard to the absence of marine shells, I shall point out in the sequel how small is the dependence we can place on this kind of negative evidence, if we desire to test by it the extent to which the land has been submerged. I cannot therefore consent to limit the probable depression and re-elevation of Scandinavia to 600 feet. But that the larger part of the glaciation of that country has been supramarine, I am willing to concede. In support of this view M. Kjerulf observes that the direction of the furrows and striae, produced by glacial abrasion, neither conforms to a general movement of floating ice from the Polar regions, nor to the shape of the existing valleys, as it would do if it had been caused by independent glaciers generated in the higher valleys after the land had acquired its actual shape. Their general arrangement and apparent irregularities are, he contends, much more in accordance with the hypothesis of there having been at one time a universal covering of ice over the whole of Norway and Sweden, like that now existing in Greenland, which, being annually recruited by fresh falls of snow, was continually pressing outwards and downwards to the coast and lower regions, after crossing many of the lower ridges, and having no relation to the minor depressions, which were all choked up with ice and reduced to one uniform level. CONTINENTAL ICE OF GREENLAND. In support of this view, he appeals to the admirable description of the continental ice of Greenland, lately published by Dr. H. Rink of Copenhagen,* who resided three or four years in the Danish settlements in Baffin's Bay, on the west coast of Greenland, between latitudes 69 and 73 degrees north. (* "Journal of Royal Geographical Society" volume 23 1853 page 145.) "In that country, the land," says Dr. Rink, "may be divided into two regions, the 'inland' and the 'outskirts.' The 'inland,' which is 800 miles from west to east, and of much greater length from north to south, is a vast unknown continent, buried under one continuous and colossal mass of permanent ice, which is always moving seaward, but a small proportion only of it in an easterly direction, since nearly the whole descends towards Baffin's Bay." At the heads of the fjords which intersect the coast, the ice is seen to rise somewhat abruptly from the level of the sea to the height of 2000 feet, beyond which the ice of the interior rises continuously as far as the eye can reach, and to an unknown altitude. All minor ridges and valleys are levelled and concealed, but here and there steep mountains protrude abruptly from the icy slope, and a few superficial lines of stones or moraines are visible at seasons when no recent snow has fallen. [23] Although all the ice is moving seaward, the greatest quantity is discharged at the heads of certain large fjords, usually about 4 miles wide, which, if the climate were milder, would be the outlet of as many great rivers. Through these the ice is now protruded in huge blocks, several miles wide, and from 1000 to 1500 feet in height or thickness. When these masses reach the fjords, they do not melt or break up into fragments, but continue their course in a solid form in the salt water, grating along the rocky bottom, which they must polish and score at depths of hundreds and even of more than 1000 feet. At length, when there is water enough to float them, huge portions, having broken off, fill Baffin's Bay with icebergs of a size exceeding any which could be produced by ordinary valley glaciers. Stones, sand, and mud are sometimes included in these bergs which float down Baffin's Bay. At some points, where the ice of the interior of Greenland reaches the coast, Dr. Rink saw mighty springs of clayey water issuing from under the edge of the ice even in winter, showing the grinding action of the glacial mass mixed with sand on the subjacent surface of the rocks. The "outskirts," where the Danish colonies are stationed, consist of numerous islands, of which Disco island is the largest in latitude 70 degrees north, and of many peninsulas, with fjords from 50 to 100 miles long, running into the land, and through which the ice above alluded to passes on its way to the bay. This area is 30, 000 square miles in extent, and contains in it some mountains 4000 feet to 5000 feet high. The perpetual snow usually begins at the height of 2000 feet, below which level the land is for the most part free from snow between June and August, and supports a vegetation of several hundred species of flowering plants, which ripen their seeds before the winter. There are even some places where phanerogamous plants have been found at an elevation of 4500 feet; a fact which, when we reflect on the immediate vicinity of so large and lofty a region of continental ice in the same latitude, well deserves the attention of the geologist, who should also bear in mind, that while the Danes are settled to the west in the "outskirts," there exists, due east of the most southern portion of this ice-covered continent, at the distance of about 1200 miles, the home of the Laplanders with their reindeer, bears, wolves, seals, walruses, and whales. If, therefore, there are geological grounds for suspecting that Scandinavia or Scotland or Wales was ever in the same glacial condition as Greenland now is, we must not imagine that the contemporaneous fauna and flora were everywhere poor and stunted, or that they may not, especially at the distance of a few hundred miles in a SOUTHWARD direction, have been very luxuriant. [24] Another series of observations made by Captain Graah, during a survey of Greenland between 1823 and 1829, and by Dr. Pingel in 1830-32, adds not a little to the geological interest of the "outskirts," in their bearing on glacial phenomena of ancient date. Those Danish investigators, with one of whom, Dr. Pingel, I conversed at Copenhagen in 1834, ascertained that the whole coast from latitude 60 to about 70 degrees north has been subsiding for the last four centuries, so that some ancient piles driven into the beach to support the boats of the settlers have been gradually submerged, and wooden buildings have had to be repeatedly shifted farther inland.* (* "Principles of Geology" chapter 30.) In Norway and Sweden, instead of such a subsiding movement, the land is slowly rising; but we have only to suppose that formerly, when it was covered like Greenland with continental ice, it sank at the rate of several feet in a century, and we shall be able to explain why marine deposits are found above the level of the sea, and why these generally overlie polished and striated surfaces of rock. We know that Greenland was not always covered with snow and ice, for when we examine the Tertiary strata of Disco Island (of the Upper Miocene period) we discover there a multitude of fossil plants, which demonstrate that, like many other parts of the arctic regions, it formerly enjoyed a mild and genial climate. Among the fossils brought from that island, latitude 70 degrees north, Professor Heer has recognised Sequoia Langsdorfii, a coniferous species which flourished throughout a great part of Europe in the Miocene period, and is very closely allied to the living Sequoia sempervirens of California. The same plant has been found fossil by Sir John Richardson within the arctic circle, far to the west on the Mackenzie River, near the entrance of Bear River, also by some Danish naturalists in Iceland to the east. The Icelandic surturbrand, or lignite, of this age has also yielded a rich harvest of plants, more than thirty-one of them, according to Steenstrup and Heer, in a good state of preservation, and no less than fifteen specifically identical with Miocene plants of Europe. Thirteen of the number are arborescent; and amongst others is a tulip-tree (Liriodendron), with its fruit and characteristic leaves, a plane (Platanus), a walnut, and a vine, affording unmistakable evidence of a climate in the parallel of the arctic circle which precludes the supposition of glaciers then existing in the neighbourhood, still less any general crust of continental ice, like that of Greenland.* (* Heer, "Recherches sur la Vegetation du Pays tertiaire" etc. 1861 page 178.) As the older Pliocene flora of the Tertiary strata of Italy, like the shells of the Coralline Crag, before adverted to, Chapter 12, indicate a temperature milder than that now prevailing in Europe, though not so warm as that of the Upper Miocene period, it is probable that the accumulation of snow and glaciers on the mountains and valleys of Greenland did not begin till after the commencement of the Pliocene period, and may not have reached its maximum until the close of that period. Norway and Sweden appear to have passed through all the successive phases of glaciation which Greenland has experienced, and others which that country will one day undergo, if the climate which it formerly enjoyed should ever be restored to it. There must have been first a period of separate glaciers in Scandinavia, then a Greenlandic state of continental ice, and thirdly, when that diminished, a second period of enormous separate glaciers filling many a valley now wooded with fir and birch. Lastly, under the influence of the Gulf Stream, and various changes in the height and extent of land in the arctic circle, a melting of nearly all the permanent ice between latitudes 60 and 70 north, corresponding to the parallels of the continental ice of Greenland, has occurred, so that we have now to go farther north than latitude 70 degrees before we encounter any glacier coming down to the sea coast. Among other signs of the last retreat of the extinct glaciers, Kjerulf and other authors describe large transverse moraines left in many of the Norwegian and Swedish glens. CHRONOLOGICAL RELATIONS OF THE HUMAN AND GLACIAL PERIODS IN SWEDEN. We may now consider whether any, and what part, of these changes in Scandinavia may have been witnessed by Man. In Sweden, in the immediate neighbourhood of Upsala, I observed, in 1834, a ridge of stratified sand and gravel, in the midst of which occurs a layer of marl, evidently formed originally at the bottom of the Baltic, by the slow growth of the mussel, cockle, and other marine shells of living species intermixed with some proper to fresh water. The marine shells are all of dwarfish size, like those now inhabiting the brackish waters of the Baltic; and the marl, in which myriads of them are embedded, is now raised more than 100 feet above the level of the Gulf of Bothnia. Upon the top of this ridge (one of those called osars in Sweden) repose several huge erratics consisting of gneiss, for the most part unrounded, from 9 to 16 feet in diameter, and which must have been brought into their present position since the time when the neighbouring gulf was already characterised by its peculiar fauna. Here, therefore, we have proof that the transport of erratics continued to take place, not merely when the sea was inhabited by the existing Testacea, but when the north of Europe had already assumed that remarkable feature of its physical geography, which separates the Baltic from the North Sea, and causes the Gulf of Bothnia to have only one-fourth of the saltness belonging to the ocean. I cannot doubt that these large erratics of Upsala were brought into their present position during the Recent period, not only because of their moderate elevation above the sea-level in a country where the land is now rising every century, but because I observed signs of a great oscillation of level which had taken place at Sodertelje, south of Stockholm (about 45 miles distant from Upsala), after the country had been inhabited by Man. I described, in the "Philosophical Transactions" for 1835, the section there laid open in digging a level in 1819, which showed that a subsidence followed by a re-elevation of land, each movement amounting to more than 60 feet, had occurred since the time when a rude hut had been built on the ancient shore. The wooden frame of the hut, with a ring of hearthstones on the floor, and much charcoal, were found, and over them marine strata, more than 60 feet thick, containing the dwarf variety of Mytilus edulis, and other brackish-water shells of the Bothnian Gulf. Some vessels put together with wooden pegs, of anterior date to the use of metals, were also embedded in parts of the same marine formation, which has since been raised, so that the upper beds are more than 60 feet above the sea-level, the hut being thus restored to about its original position relatively to the sea. We have seen in the account of the Danish kitchen-middens of the Recent period that even at the comparatively late period of their origin the waters of the Baltic had been rendered more salt than they are now. The Upsala erratics may belong to nearly the same era as these. But were we to go back to a long antecedent epoch, or to that of the Belgian and British caves with their extinct animals, and the signs they afford of a state of physical geography departing widely from the present, or to the era of the implement-bearing alluvium of St. Acheul, we might expect to find Scandinavia overwhelmed with glaciers, and the country uninhabitable by Man. At a much remoter period the same country was in the state in which Greenland now is, overspread with one uninterrupted coating of continental ice, which has left its peculiar markings on the highest mountains. This period, probably anterior to the earliest traces yet brought to light of the human race, may have coincided with the submergence of England, and the accumulation of the boulder-clay of Norfolk, Suffolk, and Bedfordshire, before mentioned. It has already been stated that the syenite and some other rocks of the Norfolk till seem to have come from Scandinavia, and there is no era when icebergs are so likely to have floated them so far south as when the whole of Sweden and Norway were enveloped in a massive crust of ice; a state of things the existence of which is deduced from the direction of the glacial furrows, and their frequent unconformity to the shape of the minor valleys. GLACIAL PERIOD IN SCOTLAND [25]. Professor Agassiz, after his tour in Scotland in 1840, announced the opinion that erratic blocks had been dispersed from the Scottish mountains as from an independent centre, and that the capping of ice had been of extraordinary thickness.* (* Agassiz, "Proceedings of the Geological Society" 1840 and "Edinburgh Philosophical Journal" 49 page 79.) Mr. Robert Chambers, after visiting Norway and Sweden, and comparing the signs of glacial action observed there with similar appearances in the Grampians, came to the conclusion that the Highlands both of Scandinavia and Scotland had once been "moulded in ice," and that the outward and downward movement and pressure of the frozen mass had not only smoothed, polished, and scratched the rocks, but had, in the course of ages, deepened and widened the valleys, and produced much of that denudation which has commonly been ascribed exclusively to aqueous action. The glaciation of the Scotch mountains was traced by him to the height of at least 3000 feet.* (* "Ancient Sea Margins" Edinburgh 1848. Glacial Phenomena "Edinburgh New Philosophical Journal" April 1853 and January 1855.) Mr. T.F. Jamieson, of Ellon, in Aberdeenshire, has recently brought forward an additional body of facts in support of this theory. According to him the Grampians were at the period of extreme cold enveloped "in one great winding sheet of snow and ice," which reached everywhere to the coast-line, the land being then more elevated than it is now. He describes the glacial furrows sculptured on the solid rocks as pointing in Aberdeenshire to the south-east, those of the valley of the Forth at Edinburgh, from west to east, and higher up the same valley at Stirling, from north-west to south-east, as they should do if the ice had followed the lines of what is now the principal drainage. The observations of Sir James Hall, Mr. Maclaren, Mr. Chambers, and Dr. Fleming, are cited by him in confirmation of this arrangement of the glacial markings, while in Sutherland and Ross-shire he shows that the glacial furrows along the north coast point northwards, and in Argyleshire westwards, always in accordance with the direction of the principal glens and fjords. Another argument is also adduced by him in proof of the ice having exerted its mechanical force in a direction from the higher and more inland country to the lower region and sea-coast. Isolated hills and minor prominences of rock are often polished and striated on the land side, while they remain rough and jagged on the side fronting the sea. This may be seen both on the east and west coast. Mention is also made of blocks of granite which have travelled from south to north in Aberdeenshire, of which there would have been no examples had the erratics been all brought by floating ice from the arctic regions when Scotland was submerged. It is also urged against the doctrine of attributing the general glaciation to submergence, that the glacial grooves, instead of radiating as they do from a centre, would, if they had been due to ice coming from the north, have been parallel to the coast-line, to which they are now often almost at right angles. The argument, moreover, which formerly had most weight in favour of floating ice, namely, that it explained why so many of the stones did not conform to the contour and direction of the minor hills and valleys, is now brought forward, and with no small effect, in favour of the doctrine of continental ice on the Greenlandic scale, which, after levelling up the lesser inequalities, would occasionally flow in mighty ice-currents, in directions often at a high angle to the smaller ridges and glens. The application to Scandinavia and Scotland of this theory makes it necessary to reconsider the validity of the proofs formerly relied on as establishing the submergence of a great part of Scotland beneath the sea, at some period subsequent to the commencement of the glacial period. In all cases where marine shells overlie till, or rest on polished and striated surfaces of rock, the evidence of the land having been under water, and having been since upheaved, remains unshaken; but this special proof rarely extends to heights exceeding 500 feet. In the basin of the Clyde we have already seen that Recent strata occur 25 feet above the sea-level, with existing species of marine testacea, and with buried canoes, and other works of art. At the higher level of 50 feet occurs the well-known raised beach of the western coast, which, according to Mr. Jamieson, contains, near Fort William and on Loch Fyne and elsewhere, an assemblage of shells implying a colder climate than that of the 25-foot terrace, or that of the present sea; just as, in the valley of the Somme, the higher-level gravels are supposed to belong to a colder period than the lower ones, and still more decidedly than that of the present era. At still greater elevations, older beds containing a still more arctic group of shells have been observed at Airdrie, 14 miles south-east of Glasgow, 524 feet above the level of the sea. They were embedded in stratified clays, with the unstratified boulder till both above and below them, and in the overlying unstratified drift were some boulders of granite which must have come from distances of 60 miles at the least.* (* Smith of Jordanhill, "Quarterly Journal of the Geological Society" volume 6 1850 page 387.) The presence of Tellina calcarea, and several other northern shells, implies a climate colder than that of the present Scottish seas. In the north of Scotland, marine shells have been found in deposits of the same age in Caithness and in Aberdeenshire at heights of 250 feet, and on the shores of the Moray Firth, as at Gamrie in Banff, at an elevation of 350 feet; and the stratified sands and beds of pebbles which belong to the same formation ascend still higher--to heights of 500 feet at least.* (* Prestwich, "Proceedings of the Geological Society" volume 2 page 545; Jamieson, "Quarterly Journal of the Geological Society" volume 16 1860.) At much greater heights, stratified masses of drift occur in which hitherto no organic remains, whether of marine or freshwater animals, have ever been found. It is still an undecided question whether the origin of all such deposits in the Grampians can be explained without the intervention of the sea. One of the most conspicuous examples has been described by Mr. Jamieson as resting on the flank of a hill called Meal Uaine, in Perthshire, on the east side of the valley of the Tummel, just below Killiecrankie. It consists of perfectly horizontal strata, the lowest portion of them 300 feet above the river and 600 feet above the sea. From this elevation to an altitude of nearly 1200 feet the same series of strata is traceable, continuously, up the slope of the mountain, and some patches are seen here and there even as high as 1550 feet above the sea. They are made up in great part of finely laminated silt, alternating with coarser materials, through which stones from 4 to 5 feet in length are scattered. These large boulders, and some smaller ones, are polished on one or more sides, and marked with glacial striae. The subjacent rocks, also, of gneiss, mica slate, and quartz, are everywhere grooved and polished as if by the passage of a glacier.* (* Jamieson, "Quarterly Journal of the Geological Society" volume 16 1860 page 360.) At one spot a vertical thickness of 130 feet of this series of strata is exposed to view by a mountain torrent, and in all more than 2000 layers of clay, sand, and gravel were counted, the whole evidently accumulated under water. Some beds consist of an impalpable mud, like putty, apparently derived from the grinding down of felspar, and resembling the mud produced by the grinding action of modern glaciers. Mr. Jamieson, when he first gave an account of this drift, inferred, in spite of the absence of marine shells, that it implied the submergence of Scotland beneath the ocean after the commencement of the glacial period, or after the era of continental ice indicated by the subjacent floor of polished and grooved rock. This conclusion would require a submergence of the land as far up as 1550 feet above the present sea-level, after which a great re-upheaval must have occurred. But the same author, having lately revisited the valley of the Tummel, suggests another possible, and I think probable, explanation of the same phenomena. The stratified drift in question is situated in a deep depression between two buttresses of rock, and if an enormous glacier be supposed to have once filled the valley of the Tummel to the height of the stratified drift, it may have dammed up the mouth of a mountain torrent by a transverse barrier, giving rise to a deep pond, in which beds of clay and sand brought down by the waters of the torrent were deposited. Charpentier in his work on the Swiss glaciers has described many such receptacles of stratified matter now in progress, and due to such blockages, and he has pointed out the remnants of ancient and similar formations left by extinct glaciers of an earlier epoch. He specially notices that angular stones of various dimensions, often polished and striated, which rest on the glacier and are let fall when the torrent undermines the side of the moving ice, descend into the small lake and become interstratified with the gravel and fine sediment brought down by the torrent into the same.* (* Charpentier, "Essai sur les Glaciers" page 63 1841.) The evidence of the former sojourn of the sea upon the land after the commencement of the glacial period was formerly inferred from the height to which erratic blocks derived from distant regions could be traced, besides the want of conformity in the glacial furrows to the present contours of many of the valleys. Some of these phenomena may now, as we have seen, be accounted for by assuming that there was once a crust of ice resembling that now covering Greenland. The Grampians in Forfarshire and in Perthshire are from 3000 to 4000 feet high. To the southward lies the broad and deep valley of Strathmore, and to the south of this again rise the Sidlaw Hills to the height of 1500 feet and upwards. On the highest summits of this chain, formed of sandstone and shale, and at various elevations, I have observed huge angular fragments of mica-schist, some 3 and others 15 feet in diameter, which have been conveyed for a distance of at least 15 miles from the nearest Grampian rocks from which they could have been detached. Others have been left strewed over the bottom of the large intervening vale of Strathmore.* (* "Proceedings of the Geological Society" volume 3 page 344.) It may be argued that the transportation of such blocks may have been due not to floating ice, but to a period when Strathmore was filled up with land ice, a current of which extended from the Perthshire Highlands to the summit of the Sidlaw Hills, and the total absence of marine or freshwater shells from all deposits, stratified or unstratified, which have any connection with these erratics in Forfarshire and Perthshire may be thought to favour such a theory. But the same mode of transport can scarcely be imagined for those fragments of mica-schist, one of them weighing from 8 to 10 tons, which were observed much farther south by Mr. Maclaren on the Pentland Hills, near Edinburgh, at the height of 1100 feet above the sea, the nearest mountain composed of this formation being 50 miles distant.* (* Maclaren, "Geology of Fife" etc. page 220.) On the same hills, also, at all elevations, stratified gravels occur which, although devoid of shells, it seems hardly possible to refer to any but a marine origin. Although I am willing, therefore, to concede that the glaciation of the Scotch mountains, at elevations exceeding 2000 feet, may be explained by land ice, it seems difficult not to embrace the conclusion that a subsidence took place not merely of 500 or 600 feet, as demonstrated by the marine shells, but to a much greater amount, as shown by the present position of erratics and some patches of stratified drift. The absence of marine shells at greater heights than 525 feet above the sea, will be treated of in a future chapter. It may in part, perhaps, be ascribed to the action of glaciers, which swept out marine strata from all the higher valleys, after the re-emergence of the land. LATEST CHANGES PRODUCED BY GLACIERS IN SCOTLAND. We may next consider the state of Scotland after its emergence from the glacial sea, when we cannot fail to be approaching the time when Man co-existed with the mammoth and other mammalia now extinct. In a paper which I published in 1840, on the ancient glaciers of Forfarshire, I endeavoured to show that some of these existed after the mountains and glens had acquired precisely their present shape,* and had left moraines even in the minor valleys, just where they would now leave them were the snow and ice again to gain ground. (* "Proceedings of the Geological Society" volume 3 page 337.) I described also one remarkable transverse mound, evidently the terminal moraine of a retreating glacier, which crosses the valley of the South Esk, a few miles above the point where it issues from the Grampians, and about 6 miles below the Kirktown of Clova. Its central part, at a place called Glenarm, is 800 feet above the level of the sea. The valley is about half a mile broad, and is bounded by steep and lofty mountains, but immediately above the transverse barrier it expands into a wide alluvial plain, several miles broad, which has evidently once been a lake. The barrier itself, about 150 feet high, consists in its lower part of till with boulders, 50 feet thick, precisely resembling the moraine of a Swiss glacier, above which there is a mass of stratified sand, varying in thickness from 50 to 100 feet, which has the appearance of consisting of the materials of the moraine rearranged in a stratified form, possibly by the waters of a glacier lake. The structure of the barrier has been laid open by the Esk, which has cut through it a deep passage about 400 yards wide. I have also given an account of another striking feature in the physical geography of Perthshire and Forfarshire, which I consider to belong to the same period; namely, a continuous zone of boulder clay, forming ridges and mounds from 50 to 70 feet high (the upper part of the mounds usually stratified), enclosing numerous lakes, some of them several miles long, and many ponds and swamps filled with shell-marl and peat. This band of till, with Grampian boulders and associated river-gravel, may be traced continuously for a distance of 34 miles, with a width of 3 1/2 miles, from near Dunkeld, by Coupar, to the south of Blairgowrie, then through the lowest part of Strathmore, and afterwards in a straight line through the greatest depression in the Sidlaw Hills, from Forfar to Lunan Bay. Although no great river now takes its course through this line of ancient lakes, moraines, and river gravel, yet it evidently marks an ancient line by which, first, a great glacier descended from the mountains to the sea, and by which, secondly, at a later period, the principal water drainage of this country was effected. The subsequent modification in geography is comparable in amount to that which has taken place since the higher level gravels of the valley of the Somme were formed, or since the Belgian caves were filled with mud and bone-breccia. [Illustration: Figure 35. Oval And Flattish Pebbles In Deserted Channels] (FIGURE 35. OVAL AND FLATTISH PEBBLES IN DESERTED CHANNELS.) Mr. Jamieson has remarked, in reference to this and some other extinct river-channels of corresponding date, that we have the means of ascertaining the direction in which the waters flowed by observing the arrangement of the oval and flattish pebbles in their deserted channels; for in the bed of a fast-flowing river such pebbles are seen to dip towards the current, as represented in Figure 35, such being the position of greatest resistance to the stream.* (* Jamieson, "Quarterly Journal of the Geological Society" volume 16 1860 page 349.) If this be admitted, it follows that the higher or mountainous country bore the same relation to the lower lands, at the time when a great river passed through this chain of lakes, as it does at present. We also seem to have a test of the comparatively modern origin of the mounds of till which surround the above-mentioned chain of lakes (of which that of Forfar is one), in the species of organic remains contained in the shell-marl deposited at their bottom. All the mammalia as well as shells are of recent species. Unfortunately, we have no information as to the fauna which inhabited the country at the time when the till itself was formed. There seem to be only three or four instances as yet known in all Scotland of mammalia having been discovered in boulder clay. Mr. R. Bald has recorded the circumstances under which a single elephant's tusk was found in the unstratified drift of the valley of the Forth, with the minuteness which such a discovery from its rarity well deserved. He distinguishes the boulder clay, under the name of "the old alluvial cover," from that more modern alluvium, in which the whales of Airthrie, described in Chapter 3, were found. This cover he says is sometimes 160 feet thick. Having never observed any organic remains in it, he watched with curiosity and care the digging of the Union Canal between Edinburgh and Falkirk, which passed for no less than 28 miles almost continuously through it. Mr. Baird, the engineer who superintended the works, assisted in the inquiry, and at one place only in this long section did they meet with a fossil, namely, at Cliftonhall, in the valley of the Almond. It lay at a depth of between 15 and 20 feet from the surface, in very stiff clay, and consisted of an elephant's tusk, 39 inches long and 13 in circumference, in so fresh a state that an ivory turner purchased it and turned part of it into chessmen before it was rescued from destruction. The remainder is still preserved in the museum at Edinburgh, but by exposure to the air it has shrunk considerably.* (* "Memoirs of the Wernerian Society" Edinburgh volume 4 page 58.) In 1817, two other tusks and some bones of the elephant, as we learn from the same authority (Mr. Bald), were met with, 3 1/2 feet long and 13 inches in circumference, lying in an horizontal position, 17 feet deep in clay, with marine shells, at Kilmaurs, in Ayrshire. The species of shells are not given.* (* Ibid. volume 4 page 63.) In another excavation through the Scotch boulder clay, made in digging the Clyde and Forth Junction Railway, the antlers of a reindeer were found at Croftamie, in Dumbartonshire, in the basin of the river Endrick, which flows into Loch Lomond. They had cut through 12 feet of till with angular and rounded stones, some of large size, and then through 6 feet of underlying clay, when they came upon the deer's horns, 18 feet from the surface, and within a foot of the sandstone on which the till rested. At the distance of a few yards, and in the same position, but a foot or two deeper, were observed marine shells, Cyprina islandica, Astarte elliptica, A. compressa, Fusus antiquus, Littorina littorea, and a Balanus. The height above the level of the sea was between 100 and 103 feet. The reindeer's horn was seen by Professor Owen, who considered it to be that of a young female of the large variety, called by the Hudson's Bay trappers the caribou. The remains of elephants, now in the museums of Glasgow and Edinburgh, purporting to come from the superficial deposits of Scotland have been referred to Elephas primigenius. In cases where tusks alone have been found unaccompanied by molar teeth, such specific determinations may be uncertain; but if any one specimen be correctly named, the occurrence of the mammoth and reindeer in the Scotch boulder-clay, as both these quadrupeds are known to have been contemporary with Man, favours the idea which I have already expressed, that the close of the glacial period in the Grampians may have coincided in time with the existence of Man in those parts of Europe where the climate was less severe, as, for example, in the basins of the Thames, Somme, and Seine, in which the bones of many extinct mammalia are associated with flint implements of the antique type. PARALLEL ROADS OF GLEN ROY IN SCOTLAND. [Illustration: Plate 2. Glen Roy and Glen Spean] (PLATE 2. VIEW OF THE MOUTHS OF GLEN ROY AND GLEN SPEAN, BY SIR T. DICK LAUDER. VV. Hill of Bohuntine. VVV. Glen Roy. V(inverted)V. Mealderry. V. Entrance of Glen Spean VV(superscript)V. Point of division between Glens Roy and Spean.) Perhaps no portion of the superficial drift of Scotland can lay claim to so modern an origin on the score of the freshness of its aspect, as that which forms what are called the Parallel Roads of Glen Roy. If they do not belong to the Recent epoch, they are at least posterior in date to the present outline of mountain and glen, and to the time when every one of the smaller burns ran in their present channels, though some of them have since been slightly deepened. The almost perfect horizontality, moreover, of the roads, one of which is continuous for about 20 miles from east to west, and 12 miles from north to south, shows that since the era of their formation no change has taken place in the relative levels of different parts of the district. [Illustration: Figure 36. Map of Glen Roy] (FIGURE 36. MAP OF THE PARALLEL ROADS OF GLEN ROY OR LOCHABER. A. five miles distant south-west from this point is Fort William, where the Lochy joins an arm of the sea, called Loch Eil. Vertical lines. Cols or watersheds at the heads of the glens--once the westward outlet of the lakes. Dots. Conspicuous delta deposits as laid down by Mr. T.F. Jamieson.) Glen Roy is situated in the Western Highlands, about 10 miles east-north-east of Fort William, near the western end of the great glen of Scotland, or Caledonian Canal, and near the foot of the highest of the Grampians, Ben Nevis. (See map, Figure 36.) Throughout nearly its whole length, a distance of more than 10 miles, three parallel roads or shelves are traced along the steep sides of the mountains, as represented in the annexed view, Plate 2, by the late Sir T. Dick Lauder, each maintaining a perfect horizontality, and continuing at exactly the same level on the opposite sides of the glen. Seen at a distance, they appear like ledges, or roads, cut artificially out of the sides of the hills; but when we are upon them, we can scarcely recognise their existence, so uneven is their surface, and so covered with boulders. They are from 10 to 60 feet broad, and merely differ from the side of the mountain by being somewhat less steep. On closer inspection, we find that these terraces are stratified in the ordinary manner of alluvial or littoral deposits, as may be seen at those points where ravines have been excavated by torrents. The parallel shelves, therefore, have not been caused by denudation, but by the deposition of detritus, precisely similar to that which is dispersed in smaller quantities over the declivities of the hills above. These hills consist of clay-slate, mica schist, and granite, which rocks have been worn away and laid bare at a few points immediately above the parallel roads. The lowest of these roads is about 850 feet above the level of the sea, the next about 212 feet higher, and the third 82 feet above the second. There is a fourth shelf, which occurs only in a contiguous valley called Glen Gluoy, which is 12 feet above the highest of all the Glen Roy roads, and consequently about 1156 feet above the level of the sea.* (* Another detached shelf also occurs at Kilfinnan. (See Map, Figure 36.)) One only, the lowest of the three roads of Glen Roy, is continued throughout Glen Spean, a large valley with which Glen Roy unites. (See Plate 2 and map, Figure 36.) As the shelves, having no slope towards the sea like ordinary river terraces, are always at the same absolute height, they become continually more elevated above the river in proportion as we descend each valley; and they at length terminate very abruptly, without any obvious cause, or any change either in the shape of the ground or in the composition or hardness of the rocks. I should exceed the limits of this work, were I to attempt to give a full description of all the geographical circumstances attending these singular terraces, or to discuss the ingenious theories which have been severally proposed to account for them by Dr. Macculloch, Sir T. Lauder, and Messrs. Darwin, Agassiz, Milne, and Chambers. There is one point, however, on which all are agreed, namely, that these shelves are ancient beaches, or littoral formations, accumulated round the edges of one or more sheets of water which once stood for a long time successively at the level of the several shelves. [Illustration: Figure 37. Section Through Side of Loch] (FIGURE 37. SECTION THROUGH SIDE OF LOCH. AB. Supposed original surface of rock. CD. Roads or shelves in the outer alluvial covering of the hill.) It is well known, that wherever a lake or marine fjord exists surrounded by steep mountains subject to disintegration by frost or the action of torrents, some loose matter is washed down annually, especially during the melting of snow, and a check is given to the descent of this detritus at the point where it reaches the waters of the lake. The waves then spread out the materials along the shore, and throw some of them upon the beach; their dispersing power being aided by the ice, which often adheres to pebbles during the winter months, and gives buoyancy to them. The annexed diagram (Figure 37) illustrates the manner in which Dr. MacCulloch and Mr. Darwin suppose "the roads" to constitute mere excrescences of the superficial alluvial coating which rests upon the hillside, and consists chiefly of clay and sharp unrounded stones. Among other proofs that the parallel roads have really been formed along the margin of a sheet of water, it may be mentioned, that wherever an isolated hill rises in the middle of the glen above the level of any particular shelf, as in Mealderry, Plate 2, a corresponding shelf is seen at the same level passing round the hill, as would have happened if it had once formed an island in a lake or fjord. Another very remarkable peculiarity in these terraces is this; each of them comes in some portion of its course to a col, or parting ridge, between the heads of glens, the explanation of which will be considered in the sequel. Those writers who first advocated the doctrine that the roads were the ancient beaches of freshwater lakes, were unable to offer any probable hypothesis respecting the formation and subsequent removal of barriers of sufficient height and solidity to dam up the water. To introduce any violent convulsion for their removal was inconsistent with the uninterrupted horizontality of the roads, and with the undisturbed aspect of those parts of the glens where the shelves come suddenly to an end. Mr. Agassiz and Dr. Buckland, desirous, like the defenders of the lake theory, to account for the limitation of the shelves to certain glens, and their absence in contiguous glens, where the rocks are of the same composition, and the slope and inclination of the ground very similar, first started the theory that these valleys were once blocked up by enormous glaciers descending from Ben Nevis, giving rise to what are called, in Switzerland and in the Tyrol, glacier-lakes. In corroboration of this view, they contended that the alluvium of Glen Roy, as well as of other parts of Scotland, agrees in character with the moraines of glaciers seen in the Alpine valleys of Switzerland. It will readily be conceded that this hypothesis was preferable to any previous lacustrine theory, by accounting more easily for the temporary existence and entire disappearance of lofty transverse barriers, although the height required for the supposed dams of ice appeared very enormous. Before the idea of glacier-lakes had been suggested by Agassiz, Mr. Darwin examined Glen Roy, and came to the opinion that the shelves were formed when the glens were still arms of the sea, and, consequently, that there never were any seaward barriers. According to him, the land emerged during a slow and uniform upward movement, like that now experienced throughout a large part of Sweden and Finland; but there were certain pauses in the upheaving process, at which times the waters of the sea remained stationary for so many centuries as to allow of the accumulation of an extraordinary quantity of detrital matter, and the excavation, at many points immediately above the sea-level, of deep notches and bare cliffs in the hard and solid rock. This theory I adopted in 1841 ("Elements," 2nd edition), as appearing to me less objectionable than any other then proposed. The phenomena most difficult to reconcile with it are, first, the abrupt cessation of the roads at certain points in the different glens; secondly, their unequal number in different valleys connecting with each other, there being three, for example, in Glen Roy, and only one in Glen Spean; thirdly, the precise horizontality of level maintained by the same shelf over a space many leagues in length, requiring us to assume, that during a rise of 1156 feet no one portion of the land was raised even a few yards above another; fourthly, the coincidence of level already alluded to of each shelf with a col, or the point forming the head of two glens, from which the rain-waters flow in opposite directions. This last-mentioned feature in the physical geography of Lochaber Mr. Darwin endeavoured to explain in the following manner. He called these cols "land-straits," and regarding them as having been anciently sounds or channels between islands, he pointed out that there is a tendency in such sounds to be silted up, and always the more so in proportion to their narrowness. In a chart of the Falkland Islands, by Captain Sulivan, R.N., it appears that there are several examples there of straits where the soundings diminish regularly towards the narrowest part. One is so nearly dry that it can be walked over at low water, and another, no longer covered by the sea, is supposed to have recently dried up in consequence of a small alteration in the relative level of sea and land. "Similar straits," observes Mr. Chambers, "hovering, in character, between sea and land, and which may be called fords, are met with in the Hebrides. Such, for example, is the passage dividing the islands of Lewis and Harris, and that between North Uist and Benbecula, both of which would undoubtedly appear as cols, coinciding with a terrace or raised beach, all round the islands if the sea were to subside."* (* R. Chambers, "Ancient Sea Margins" page 114.) The first of the difficulties above alluded to, namely, the non-extension of the shelves over certain parts of the glens, might be explained, said Mr. Darwin, by supposing in certain places a quick growth of green turf on a good soil, which prevented the rain from washing away any loose materials lying on the surface. But wherever the soil was barren, and where green sward took long to form, there may have been time for the removal of the gravel. In one case an intermediate shelf appears for a short distance (three quarters of a mile) on the face of the mountain called Tombhran, between the two upper shelves, and is seen nowhere else. It occurs where there was the longest space of open water, and where the waves may have acquired a more than ordinary power to heap up detritus. The unequal number of the shelves in valleys communicating with each other, and in which the boundary rocks are similar in composition, and the general absence of any shelves at corresponding altitudes in glens on the opposite watershed, like that of the Spey, and in valleys where the waters flow eastward, are difficulties attending the marine theory which have never yet been got over. Mr. T.F. Jamieson, before cited, has, during a late visit to Lochaber, in 1861, observed many facts highly confirmatory of the hypothesis of glacier-lakes which, as I have already stated, was originally advanced by Mr. Agassiz. In the first place, he found much superficial scoring and polishing of rocks, and accumulation of boulders at those points where signs of glacial action ought to appear, if ice had once dammed up the waters of the glens in which the "roads" occur. Ben Nevis may have sent down its glaciers from the south, and Glen Arkaig from the north, for the mountains at the head of the last-mentioned glen are 3000 feet high, and may, together with other tributary glens, have helped to choke up the great Caledonian valley with ice, so as to block up for a time the mouths of the Spean, Roy, and Gluoy. The temporary conversion of these glens into glacier-lakes is the more conceivable, because the hills at their upper ends not being lofty nor of great extent, they may not have been filled with ice at a time when great glaciers were generated in other adjoining and much higher regions. Secondly. The shelves, says Mr. Jamieson, are more precisely defined and unbroken than any of the raised beaches or acknowledged ancient coast-lines visible on the west of Scotland, as in Argyllshire, for example. Thirdly. At the level of the lower shelf in Glen Roy, at points where torrents now cut channels through the shelf as they descend the hill-side, there are small delta-like extensions of the shelf, perfectly preserved, as if the materials, whether fine or coarse, had originally settled there in a placid lake, and had not been acted upon by tidal currents, mingling them with the sediment of other streams. These deltas are too entire to allow us to suppose that they have at any time since their origin been exposed to the waves of the sea. Fourthly. The alluvium on the cols or watersheds, before alluded to, is such as would have been formed if the waters of the rivers had been made to flow east, or out of the upper ends of the supposed glacier-lakes, instead of escaping at the lower ends, in a westerly direction, where the great blockages of ice are assumed to have occurred. In addition to these arguments of Mr. Jamieson, I may mention that in Switzerland, at present, no testacea live in the cold waters of glacier-lakes; so that the entire absence of fossil shells, whether marine or freshwater, in the stratified materials of each shelf, would be accounted for if the theory above mentioned be embraced. When I examined "the parallel roads" in 1825, in company with Dr. Buckland, neither this glacier theory nor Mr. Darwin's suggestion of ancient sea-margins had been proposed, and I have never since revisited Lochaber. But I retain in my memory a vivid recollection of the scenery and physical features of the district, and I now consider the glacier-lake theory as affording by far the most satisfactory solution of this difficult problem. The objection to it, which until lately appeared to be the most formidable, and which led Mr. Robert Chambers in his "Sea Margins," to reject it entirely, was the difficulty of conceiving how the waters could be made to stand so high in Glen Roy as to allow the uppermost shelf to be formed. Grant a barrier of ice in the lower part of the glen of sufficient altitude to stop the waters from flowing westward, still, what prevented them from escaping over the col at the head of Glen Glaster? This col coincides exactly in level, as Mr. Milne Home first ascertained, with the second or middle shelf of Glen Roy. The difficulty here stated appears now to be removed by supposing that the higher lines or roads were formed before the lower ones, and when the quantity of ice was most in excess. We must imagine that at the time when the uppermost shelf of Glen Roy was forming in a shallow lake, the lower part of that glen was filled up with ice, and, according to Mr. Jamieson, a glacier from Loch Treig then protruded itself across Glen Spean and rested on the flank of the hill on the opposite side in such a manner as effectually to prevent any water from escaping over the Glen Glaster col. The proofs of such a glacier having actually existed at the point in question consist, he says, in numerous cross striae observable in the bottom of Glen Spean, and in the presence of moraine matter in considerable abundance on the flanks of the hill extending to heights above the Glen Glaster col. When the ice shrank into less dimensions the second shelf would be formed, having its level determined by the col last mentioned, Glen Spean in the meantime being filled with a glacier. Finally, the ice blockage common to glens Roy, Spean, and Laggan, which consisted probably of a glacier from Ben Nevis, gave rise to the lowest and most extensive lake, the waters of which escaped over the pass of Muckul or the col at the head of Loch Laggan, which, as Mr. Jamieson has now ascertained: agrees precisely in level with the lowest of all the shelves, and where there are unequivocal signs of a river having flowed out for a considerable period. Dr. Hooker has described some parallel terraces, very analogous in their aspect to those of Glen Roy, as existing in the higher valleys of the Himalaya, of which his pencil has given us several graphic illustrations. He believes these Indian shelves to have originated on the borders of glacier-lakes, the barriers of which were usually formed by the ice and moraines of lateral or tributary glaciers, which descended into and crossed the main valley, as we have supposed in the case of Glen Roy; but others he ascribes to the terminal moraine of the principal glacier itself, which had retreated during a series of milder seasons, so as to leave an interval between the ice and the terminal moraine. This interspace caused by the melting of ice becomes filled with water and forms a lake, the drainage of which usually takes place by percolation through the porous parts of the moraine, and not by a stream overflowing that barrier. Such a glacier-lake Dr. Hooker actually found in existence near the head of the Yangma valley in the Himalaya. It was moreover partially bounded by recently formed marginal terraces or parallel roads, implying changes of level in the barrier of ice and moraine matter.* (* Hooker, "Himalayan Journal" volume 1 page 242; 2 pages 119, 121, 166. I have also profited by the author's personal explanations.) It has been sometimes objected to the hypothesis of glacier-lakes, as applied to the case of Glen Roy, that the shelves must have taken a very long period for their formation. Such a lapse of time, it is said, might be consistent with the theory of pauses or stationary periods in the rise of the land during an intermittent upward movement, but it is hardly compatible with the idea of so precarious and fluctuating a barrier as a mass of ice. But the reader will have seen that the permanency of level in such glacier-lakes has no necessary connection with minor changes in the height of the supposed dam of ice. If a glacier descending from higher mountains through a tributary glen enters the main valley in which there happens to be no glacier, the river is arrested in its course and a lake is formed. The dam may be constantly repaired and may vary in height several hundreds of feet without affecting the level of the lake, so long as the surplus waters escape over a col or parting ridge of rock. The height at which the waters remain stationary is determined solely by the elevation of the col, and not by the barrier of ice, provided the barrier is higher than the col. But if we embrace the theory of glacier-lakes, we must be prepared to assume not only that the sea had nothing to do with the original formation of the "parallel roads," but that it has never, since the disappearance of the lakes, risen in any one of the glens up to the level of the lowest shelf, which is about 850 feet high; for in that case the remarkable persistency and integrity of the roads and deltas, before described, must have been impaired. We have seen that 50 miles to the south of Lochaber, the glacier formations of Lanarkshire with marine shells of arctic character have been traced to the height of 524 feet. About 50 miles to the south-east in Perthshire are those stratified clays and sands, near Killiecrankie, which were once supposed to be of submarine origin, and which in that case would imply the former submergence of what is now dry land to the extent of 1550 feet, or several hundred feet beyond the highest of the parallel roads. Even granting that these laminated drifts may have had a different origin, as above suggested, there are still many facts connected with the distribution of erratics and the striation of rocks in Scotland which are not easily accounted for without supposing the country to have sunk, since the era of continental ice, to a greater depth than 525 feet, the highest point to which marine shells have yet been traced. After what was said of the pressure and abrading power of a general crust of ice, like that now covering Greenland, it is almost superfluous to say that the parallel roads must have been of later date than such a state of things, for every trace of them must have been obliterated by the movement of such a mass of ice. It is no less clear that as no glacier-lakes can now exist in Greenland [26], so there could have been none in Scotland, when the mountains were covered with one great crust of ice. It may, however, be contended that the parallel roads were produced when the general crust of ice first gave place to a period of separate glaciers, and that no period of deep submergence ever intervened in Lochaber after the time of the lakes. Even in that case, however, it is difficult not to suppose that the Glen Roy country participated in the downward movement which sank part of Lanarkshire 525 feet beneath the sea, subsequently to the first great glaciation of Scotland. Yet that amount of subsidence might have occurred, and even a more considerable one, without causing the sea to rise to the level of the lowest shelf, or to a height of 850 feet above the present sea-level. This is a question on which I am not prepared at present to offer a decided opinion. Whether the horizontality of the shelves or terrace-lines is really as perfect as has been generally assumed is a point which will require to be tested by a more accurate trigonometrical survey than has yet been made. The preservation of precisely the same level in the lowest line throughout the glens of Roy, Spean, and Laggan, for a distance of 20 miles east and west, and 10 or 12 miles north and south, would be very wonderful if ascertained with mathematical precision. Mr. Jamieson, after making in 1862 several measurements with a spirit-level, has been led to suspect a rise in the lowest shelf of one foot in a mile in a direction from west to east, or from the mouth of Glen Roy to a point 6 miles east of it in Glen Spean. To confirm such observations, and to determine whether a similar rate of rise continues eastward, as far as the pass of Muckul, would be most important. On the whole, I conclude that the Glen Roy terrace-lines and those of some neighbouring valleys, were formed on the borders of glacier-lakes, in times long subsequent to the principal glaciation of Scotland. They may perhaps have been nearly as late, especially the lowest of the shelves, as that portion of the Pleistocene period in which Man co-existed in Europe with the mammoth. CHAPTER 14. -- CHRONOLOGICAL RELATIONS OF THE GLACIAL PERIOD AND THE EARLIEST SIGNS OF MAN'S APPEARANCE IN EUROPE--CONTINUED. Signs of extinct Glaciers in Wales. Great Submergence of Wales during the Glacial Period proved by Marine Shells. Still greater Depression inferred from Stratified Drift. Scarcity of Organic Remains in Glacial Formations. Signs of extinct Glaciers in England. Ice Action in Ireland. Maps illustrating successive Revolutions in Physical Geography during the Pleistocene Period. Southernmost Extent of Erratics in England. Successive Periods of Junction and Separation of England, Ireland, and the Continent. Time required for these Changes. Probable Causes of the Upheaval and Subsidence of the Earth's Crust. Antiquity of Man considered in relation to the Age of the existing Fauna and Flora. EXTINCT GLACIERS IN WALES. The considerable amount of vertical movement in opposite directions, which was suggested in the last chapter, as affording the most probable explanation of the position of some of the stratified and fossiliferous drifts of Scotland, formed since the commencement of the glacial period, will appear less startling if it can be shown that independent observations lead us to infer that a geographical revolution of still greater magnitude accompanied the successive phases of glaciation through which the Welsh mountains have passed. That Wales was once an independent centre of the dispersion of erratic blocks has long been acknowledged. Dr. Buckland published in 1842 his reasons for believing that the Snowdonian mountains in Caernarvonshire were formerly covered with glaciers, which radiated from the central heights through the seven principal valleys of that chain, where striae and flutings are seen on the polished rocks directed towards as many different points of the compass. He also described the "moraines" of the ancient glaciers, and the rounded masses of polished rock, called in Switzerland "roches moutonnees." His views respecting the old extinct glaciers of North Wales were subsequently confirmed by Mr. Darwin, who attributed the transport of many of the larger erratic blocks to floating ice. Much of the Welsh glacial drift had already been shown by Mr. Trimmer to have had a submarine origin, and Mr. Darwin maintained that when the land rose again to nearly its present height, glaciers filled the valleys, and "swept them clean of all the rubbish left by the sea."* (* "Philosophical Magazine" series 3 volume 21 page 180.) Professor Ramsay, in a paper read to the Geological Society in 1851, and in a later work on the glaciation of North Wales, described three successive glacial periods, during the first of which the land was much higher than it now is, and the quantity of ice excessive; secondly, a period of submergence when the land was 2300 feet lower than at present, and when the higher mountain tops only stood out of the sea as a cluster of low islands, which nevertheless were covered with snow; and lastly, a third period when the marine boulder drift formed in the middle period was ploughed out of the larger valleys by a second set of glaciers, smaller than those of the first period. This last stage of glaciation may have coincided with that of the parallel roads of Glen Roy, spoken of in the last chapter. In Wales it was certainly preceded by submergence, and the rocks had been exposed to glacial polishing and friction before they sank. Fortunately the evidence of the sojourn of the Welsh mountains beneath the waters of the sea is not deficient, as in Scotland, in that complete demonstration which the presence of marine shells affords. The late Mr. Trimmer discovered such shells on Moel Tryfan, in North Wales, in drift elevated more than 1300 feet above the level of the sea. It appears from his observations, and those of the late Edward Forbes, corroborated by others of Professor Ramsay and Mr. Prestwich, that about twelve species of shells, including Fusus bamfius, F. antiquus, Venus striatula (Forbes and Hanley), have been met with at heights of between 1000 and 1400 feet, in drift, reposing on a surface of rock which had been previously exposed to glacial friction and striation.* (* Ramsay, "Quarterly Journal of the Geological Society" volume 8 1852 page 372.) The shells, as a whole, are those of the glacial period, and not of the Norwich Crag. Two localities of these shells in Wales, in addition to that first pointed out by Mr. Trimmer, have since been observed by Professor Ramsay, who, however, is of opinion that the amount of submergence can by no means be limited to the extreme height to which the shells happen to have been traced; for drift of the same character as that of Moel Tryfan extends continuously to the height of 2300 feet. [27] RARITY OF ORGANIC REMAINS IN GLACIAL FORMATIONS. The general dearth of shells in such formations, below as well as above the level at which Mr. Trimmer first found them, deserves notice. Whether we can explain it or not, it is a negative character which seems to belong very generally to deposits formed in glacial seas. The porous nature of the strata, and the length of time during which they have been permeated by rain-water, may partly account, as we hinted in a former chapter, for the destruction of organic remains. But it is also possible that they were originally scarce, for we read of the waters of the sea being so freshened and chilled by the melting of ice-bergs in some Norwegian and Icelandic fjords, that the fish are driven away, and all the mollusca killed. The moraines of glaciers are always from the first devoid of shells, and if transported by ice-bergs to a distance, and deposited where the ice melts, may continue as barren of every indication of life as they were when they originated. Nevertheless, it may be said, on the other hand, that herds of seals and walruses crowd the floating ice of Spitzbergen in latitude 80 degrees north, of which Mr. Lamont has recently given us a lively picture,*nand huge whales fatten on myriads of pteropods in polar regions. (* "Seasons with the Sea-Horses" 1861.) It had been suggested that the bottom of the sea, at the era of extreme submergence in Scotland and Wales, was so deep as to reach the zero of animal life, which, in part of the Mediterranean (the Aegean, for example), the late Edward Forbes fixed, after a long series of dredgings, at 300 fathoms. But the shells of the glacial drift of Scotland and Wales, when they do occur, are not always those of deep seas; and, moreover, our faith in the uninhabitable state of the ocean at great depths has been rudely shaken, by the recent discovery of Captain McClintock and Dr. Wallich, of starfish in water more than a thousand fathoms deep (7560 feet!), midway between Greenland and Iceland. That these radiata were really dredged up from the bottom, and that they had been living and feeding there, appeared from the fact that their stomachs were full of Globigerina, of which foraminiferous creatures, both living and dead, the oozy bed of the ocean at that vast depth was found to be exclusively composed. [28] Whatever may be the cause, the fact is certain, that over large areas in Scotland, Ireland, and Wales, I might add throughout the northern hemisphere on both sides of the Atlantic, the stratified drift of the glacial period is very commonly devoid of fossils, in spite of the occurrence here and there, at the height of 500, 700, and even 1400 feet, of marine shells. These, when met with, belong, with few exceptions, to known living species. I am therefore unable to agree with Mr. Kjerulf that the amount of former submergence can be measured by the extreme height at which shells happen to have been found. GLACIAL FORMATIONS IN ENGLAND. [Illustration: Figure 38. Dome-shaped Rocks] (FIGURE 38. DOME-SHAPED ROCKS, OR "ROCHES MOUTONEES," IN THE VALLEY OF THE ROTHAY, NEAR AMBLESIDE, FROM A DRAWING BY E. HULL, F.G.S.* (* "Edinburgh New Philosophical Journal" volume 11 Plate 1 page 31 1860.)) The mountains of Cumberland and Westmorland, and the English lake district, afford equally unequivocal vestiges of ice-action not only in the form of polished and grooved surfaces, but also of those rounded bosses before mentioned as being so abundant in the Alpine valleys of Switzerland, where glaciers exist, or have existed. Mr. Hall has lately published a faithful account of these phenomena, and has given a representation of some of the English "roches moutonnees," which precisely resemble hundreds of dome-shaped protuberances in North Wales, Sweden, and North America.* (* Hull, "Edinburgh New Philosophical Journal" July 1860.) The marks of glaciation on the rocks, and the transportation of erratics from Cumberland to the eastward, have been traced by Professor Phillips over a large part of Yorkshire, extending to a height of 1500 feet above the sea; and similar northern drift has been observed in Lancashire, Cheshire, Derbyshire, Shropshire, Staffordshire, and Worcestershire. It is rare to find marine shells, except at heights of 200 or 300 feet; but a few instances of their occurrence have been noticed, especially of Turritella communis (a gregarious shell), far in the interior, at elevations of 500 feet, and even of 700 in Derbyshire, and some adjacent counties, as I learn from Mr. Binney and Mr. Prestwich. Such instances are of no small theoretical interest, as enabling us to account for the scattering of large erratic blocks at equal or much greater elevations, over a large part of the northern and midland counties, such as could only have been conveyed to their present sites by floating ice. Of this nature, among others, is a remarkable angular block of syenitic greenstone, 4 1/2 feet by 4 feet square, and 2 feet thick, which Mr. Darwin describes as lying on the summit of Ashley Heath, in Staffordshire, 803 feet above the sea, resting on New Red Sandstone.* (* Ancient Glaciers of Caernarvonshire, "Philosophical Magazine" series 3, 21 page 180.) SIGNS OF ICE-ACTION AND SUBMERGENCE IN IRELAND DURING THE GLACIAL PERIOD. In Ireland we encounter the same difficulty as in Scotland in determining how much of the glaciation of the higher mountains should be referred to land glaciers, and how much to floating ice, during submergence. The signs of glacial action have been traced by Professor Jukes to elevations of 2500 feet in the Killarney district, and to great heights in other mountainous regions; but marine shells have rarely been met with higher than 600 feet above the sea, and that chiefly in gravel, clay, and sand in Wicklow and Wexford. They are so rare in the drift east of the Wicklow mountains, that an exception to the rule, lately observed at Ballymore Eustace, by Professor Jukes, is considered as a fact of no small geological interest. The wide extent of drift of the same character, spread over large areas in Ireland, shows that the whole island was, in some part of the glacial period, an archipelago, as represented in the maps, Figures 39 and 40. Speaking of the Wexford drift, the late Professor E. Forbes states that Sir H. James found in it, together with many of the usual glacial shells, several species which are characteristic of the Crag; among others the reversed variety of Fusus antiquus, called F. contrarius, and the extinct species Nucula Cobboldiae, and Turritella incrassata. Perhaps a portion of this drift of the south of Ireland may belong to the close of the Pliocene period, and may be of a somewhat older date than the shells of the Clyde, alluded to in Chapter 13. They may also correspond still more nearly in age with the fauna of the uppermost strata of the Norwich Crag, occurring at Chillesford. [29] The scarcity of mammalian remains in the Irish drift favours the theory of its marine origin. In the superficial deposits of the whole island, I have only met with three recorded examples of the mammoth, one in the south near Dungarvan, where the bones of Elephas primigenius, two species of bear (Ursus arctos and Ursus spelaeus?), the reindeer, horse, etc., were found in a cave;* another in the centre of the island near Belturbet, in the county of Cavan. (* E. Brenan and Dr. Carte, Dublin 1859.) Perhaps the conversion into land of the bed of the glacial sea, and the immigration into the newly upheaved region of the elephant, rhinoceros, and hippopotamus, which co-existed with the fabricators of the St. Acheul flint hatchets, were events which preceded in time the elevation of the Irish drift, and the union of that island with England. Ireland may have continued for a longer time in the state of an archipelago, and was therefore for a much shorter time inhabited by the large extinct Pleistocene pachyderms. In one of the reports of the Geological Survey of Ireland, published in 1859, Professor Jukes, in explanation of sheet 184 of the maps, alludes to beds of sand and gravel, and signs of the polishing and furrowing of the rocks in the counties of Kerry and Killarney, as high as 2500 feet above the sea, and supposes (perhaps with good reason) that the land was depressed even to that extent. He observes that above that elevation (2500 feet) the rocks are rough, and not smoothed, as if by ice. Some of the drift was traced as high as 1500 feet, the highest hills there exceeding 3400 feet. Mr. Jukes, however, is by no means inclined to insist on submergence to the extent of 2500 feet, as he is aware that ice, like that now prevailing in Greenland, might explain most, if not all, the appearances of glaciation in the highest regions. Although the course taken by the Irish erratics in general is such that their transportation seems to have been due to floating ice or coast-ice, yet some granite blocks have travelled from south to north, as recorded by Sir R. Griffiths, namely, those of the Ox Mountains in Sligo; a fact from which Mr. Jamieson infers that those mountains formed at one time a centre of dispersion. In the same part of Ireland, the general direction in which the boulders have travelled is everywhere from north-west to south-east, a course directly at right angles to the prevailing trend of the present mountain ridges. MAPS ILLUSTRATING SUCCESSIVE REVOLUTIONS IN PHYSICAL GEOGRAPHY DURING THE PLEISTOCENE PERIOD. [Illustration: Figure 39. Map Of The British Isles] (FIGURE 39. MAP OF THE BRITISH ISLES AND PART OF THE NORTH-WEST OF EUROPE, SHOWING THE GREAT AMOUNT OF SUPPOSED SUBMERGENCE OF LAND BENEATH THE SEA DURING PART OF THE GLACIAL PERIOD. The submergence of Scotland is to the extent of 2000 feet, and of other parts of the British Isles, 1300. In the map, the dark shade expresses the land which alone remained above water. The area shaded by diagonal lines is that which cannot be shown to have been under water at the period of floating ice by the evidence of erratics, or by marine shells of northern species. How far the several parts of the submerged area were simultaneously or successively laid under water, in the course of the glacial period, cannot, in the present state of our knowledge, be determined.) [Illustration: Figure 40. Map British Islands] (FIGURE 40. MAP SHOWING WHAT PARTS OF THE BRITISH ISLANDS WOULD REMAIN ABOVE WATER AFTER A SUBSIDENCE OF THE AREA TO THE EXTENT OF 600 FEET. The authorities to whom I am indebted for the information contained in this map are--for: SCOTLAND: A. Geikie, Esquire, F.G.S., and T.F. Jamieson, Esquire, of Ellon, Aberdeenshire. ENGLAND: For the counties of: Yorkshire, Lancashire, and Durham: Colonel Sir Henry James, R.E. Dorsetshire, Hampshire, and Isle of Wight: H.W. Bristow, Esquire. Gloucestershire, Somersetshire, and part of Devon: R. Etheridge, Esquire. Kent and Sussex: Frederick Drew, Esquire. Isle of Man: W. Whitaker, Esquire. IRELAND: Reduced from a contour map constructed by Lieutenant Larcom, R.E., in 1837, for the Railway Commissioners.) [Illustration: Figure 41. Map Of Part Of The North-West Of Europe] (FIGURE 41. MAP OF PART OF THE NORTH-WEST OF EUROPE, INCLUDING THE BRITISH ISLES, SHOWING THE EXTENT OF SEA WHICH WOULD BECOME LAND IF THERE WERE A GENERAL RISE OF THE AREA TO THE EXTENT OF 600 FEET. The darker shade expresses what is now land, the lighter shade the space intervening between the present coastline and the 100 fathom line, which would be converted by such a movement into land. The original of this map will be found in Sir H. de la Beche's "Theoretical Researches" page 190, 1834, but several important corrections have been introduced into it from recently published Admiralty Surveys, especially: 1st. A deep channel passing from the North Sea into the entrance of the Baltic. 2nd. The more limited westerly extension of the West Coast of Ireland.) The late Mr. Trimmer, before referred to, has endeavoured to assist our speculations as to the successive revolutions in physical geography, through which the British Islands have passed since the commencement of the glacial period, by four "sketch maps" as he termed them, in the first of which he gave an ideal restoration of the original Continental period, called by him the first elephantine period, or that of the forest of Cromer, before described. He was not aware that the prevailing elephant of that era (E. meridionalis) was distinct from the mammoth. At this era he conceived Ireland and England to have been united with each other and with France, but much of the area represented as land in the map, Figure 41, was supposed to be under water. His second map, of the great submergence of the glacial period, was not essentially different from our map, Figure 39. His third map expressed a period of partial re-elevation, when Ireland was reunited to Scotland and the north of England; but England still separated from France. This restoration appears to me to rest on insufficient data, being constructed to suit the supposed area over which the gigantic Irish deer, or Megaceros, migrated from east to west, also to explain an assumed submergence of the district called the Weald, in the south-east of England, which had remained land during the grand glacial submergence. The fourth map is a return to nearly the same continental conditions as the first--Ireland, England, and the Continent being united. This he called the second elephantine period; and it would coincide very closely with that part of the Pleistocene era in which Man co-existed with the mammoth, and when, according to Mr. Trimmer's hypothesis previously indicated by Mr. Godwin-Austen, the Thames was a tributary of the Rhine.* (* Joshua Trimmer, "Quarterly Journal of the Geological Society" volume 9 1853, Plate 13, and Godwin-Austen, ibid. volume 7 1851 page 134 and Plate 7.) These geographical speculations were indulged in ten years after Edward Forbes had published his bold generalisations on the geological changes which accompanied the successive establishment of the Scandinavian, Germanic, and other living floras and faunas in the British Islands, and, like the theories of his predecessor, were the results of much reflection on a vast body of geological facts. It is by repeated efforts of this kind, made by geologists who are prepared for the partial failure of some of their first attempts, that we shall ultimately arrive at a knowledge of the long series of geographical revolutions which have followed each other since the beginning of the Pleistocene period. The map, Figure 39, will give some idea of the great extent of land which would be submerged, were we to infer, as many geologists have done, from the joint evidence of marine shells, erratics, glacial striae and stratified drift at great heights, that Scotland was, during part of the glacial period, 2000 feet below its present level, and other parts of the British Isles, 1300 feet. A subsidence to this amount can be demonstrated in the case of North Wales by marine shells. In the lake district of Cumberland, in Yorkshire, and in Ireland, we must depend on proofs derived from glacial striae and the transportation of erratics for so much of the supposed submergence as exceeds 600 feet. As to central England, or the country north of the Thames and Bristol Channel, marine shells of the glacial period sometimes reach as high as 600 and 700 feet, and erratics still higher, as we have seen above. But this region is of such moderate elevation above the sea, that it would be almost equally laid under water, were there a sinking of no more than 600 feet. To make this last proposition clear, I have constructed, from numerous documents, many of them unpublished, the map, Figure 40, which shows how that small amount of subsidence would reduce the whole of the British Isles to an archipelago of very small islands, with the exception of parts of Scotland, and the north of England and Wales, where four islands of considerable dimensions would still remain. The map does not indicate a state of things supposed to have prevailed at any one moment of the past, because the district south of the Thames and the Bristol Channel seems to have remained land during the whole of the glacial period, at a time when the northern area was under water. The map simply represents the effects of a downward movement of a hundred fathoms, or 600 English feet, assumed to be uniform over the whole of the British Isles. It shows the very different state of the physical geography of the area in question, when contrasted with the results of an opposite movement, or one of upheaval, to an equal amount, of which Sir Henry de la Beche had already given us a picture, in his excellent treatise called "Theoretical Researches."* (* Also repeated in De la Beche's "Geological Observer.") His map I have borrowed (Figure 41), after making some important corrections in it. If we are surprised when looking at the first map, Figure 40, at the vast expanse of sea which so moderate a subsidence as 600 feet would cause, we shall probably be still more astonished to perceive, in Figure 41, that a rise of the same number of feet would unite all the British Isles, including the Hebrides, Orkneys, and Shetlands, with one another and the Continent, and lay dry the sea now separating Great Britain from Sweden and Denmark. It appears from soundings made during various Admiralty surveys, that the gained land thus brought above the level of the sea, instead of presenting a system of hills and valleys corresponding with those usually characterising the interior of most of our island, would form a nearly level terrace, or gently inclined plane, sloping outwards like those terraces of denudation and deposition which I have elsewhere described as occurring on the coasts of Sicily and the Morea.* (* "Manual of Geology" page 74.) It seems that, during former and perhaps repeated oscillations of level undergone by the British Isles, the sea has had time to cut back the cliffs for miles in many places, while in others the detritus derived from wasting cliffs drifted along the shores, together with the sediment brought down by rivers and swept by currents into submarine valleys, has exerted a levelling power, filling up such depressions as may have pre-existed. Owing to this twofold action few marked inequalities of level have been left on the sea-bottom, the "silver-pits" off the mouth of the Humber offering a rare exception to the general rule, and even there the narrow depression is less than 300 feet in depth. Beyond the 100 fathom line, the submarine slope surrounding the British coast is so much steeper that a second elevation of equal amount (or of 600 feet) would add but slightly to the area of gained land; in other words, the 100 and 200 fathom lines run very near each other.* (* De la Beche, "Geological Researches" page 191.) The naturalist would have been entitled to assume the former union, within the Pleistocene period, of all the British Isles with each other and with the Continent, as expressed in the map, Figure 41, even if there had been no geological facts in favour of such a junction. For in no other way would he be able to account for the identity of the fauna and flora found throughout these lands. Had they been separated ever since the Miocene period, like Madeira, Porto Santo, and the Desertas, constituting the small Madeiran Archipelago, we might have expected to discover a difference in the species of land-shells, not only when Ireland was compared to England, but when different islands of the Hebrides were contrasted one with another, and each of them with England. It would not, however, be necessary, in order to effect the complete fusion of the animals and plants which we witness, to assume that all parts of the area formed continuous land at one and the same moment of time, but merely that the several portions were so joined within the Pleistocene era as to allow the animals and plants to migrate freely in succession from one district to another. SOUTHERNMOST EXTENT OF ERRATICS IN ENGLAND. In reference to that portion of the south of England which is marked by diagonal lines in Figure 39, the theory of its having been an area of dry land during the period of great submergence and floating ice does not depend merely on negative evidence, such as the absence of the northern drift or boulder clay on its surface; but we have also, in favour of the same conclusion, the remarkable fact of the presence of erratic blocks on the southern coast of Sussex, implying the existence there of an ancient coast-line at a period when the cold must have been at its height. These blocks are to be seen in greatest number at Pagham and Selsea, 15 miles south of Chichester, in latitude 50 degrees 40 minutes north. They consist of fragments of granite, syenite and greenstone, as well as of Devonian and Silurian rocks, some of them of large size. I measured one of granite at Pagham, 27 feet in circumference. They are not of northern origin, but must have come from the coast of Normandy or Brittany, or from land which may once have existed to the south-west, in what is now the English Channel. They were probably drifted into their present site by coast ice, and the yellow clay and gravel in which they are embedded are a littoral formation, as shown by the shells. Beneath the gravel containing these large erratics, is a blue mud in which skeletons of Elephas antiquus, and other mammalia, have been observed. Still lower occurs a sandy loam, from which Mr. R.G. Austen* has collected thirty-eight species of marine shells, all Recent, but forming an assemblage differing as a whole from that now inhabiting the English Channel. (* "Quarterly Journal of the Geological Society" volume 13 1857 page 50.) The presence among them of Lutraria rugosa and Pecten polymorphus, not known to range farther north in the actual seas than the coast of Portugal, indicates a somewhat warmer temperature at the time when they flourished. Subsequently, there must have been great cold when the Selsea erratics were drifted into their present position, and this cold doubtless coincided in time with a low temperature farther north. [30] These transported rocks of Sussex are somewhat older than a sea-beach with Recent marine shells which at Brighton is covered by Chalk rubble, called the "elephant-bed" which I cannot describe in this place, but I allude to it as one of many geological proofs of the former existence of a seashore in this region, and of ancient cliffs bounding the channel between France and England, all of older date than the close of the glacial period. [31] In order to form a connected view of the most simple series of changes in physical geography which can possibly account for the phenomena of the glacial period, and the period of the establishment of the present provinces of animals and plants, the following geographical states of the British and adjoining areas may be enumerated. First, a continental period, towards the close of which the forest of Cromer flourished: when the land was at least 500 feet above its present level, perhaps much higher, and its extent probably greater than that given in the map, Figure 41. Secondly, a period of submergence, by which the land north of the Thames and Bristol Channel, and that of Ireland, was gradually reduced to such an archipelago as is pictured in map, Figure 40; and finally to such a general prevalence of sea as is seen in map, Figure 39. This was the period of great submergence and of floating ice, when the Scandinavian flora, which occupied the lower grounds during the first continental period, may have obtained exclusive possession of the only lands not covered with perpetual snow. Thirdly, a second continental period when the bed of the glacial sea, with its marine shells and erratic blocks, was laid dry, and when the quantity of land equalled that of the first period, and therefore probably exceeded that represented in the map, Figure 41. During this period there were glaciers in the higher mountains of Scotland and Wales, and the Welsh glaciers, as we have seen, pushed before them and cleared out the marine drift with which some valleys had been filled during the period of submergence. The parallel roads of Glen Roy are referable to some part of the same era. As a reason for presuming that the land which in map, Figure 41, is only represented as 600 feet above its present level, was during part of this period much higher, Professor Ramsay has suggested that, as the previous depression far exceeded 100 fathoms (amounting in Wales to 1400 feet, as shown by marine shells, and to 2300, by stratified drift), it is not improbable that the upward movement was on a corresponding scale. In passing from the period of chief submergence to this second continental condition of things, we may conceive a gradual change first from that of Map 39 to Map 40, then from the latter phase to that of Map 41, and finally to still greater accessions of land. During this last period the passage of the Germanic flora into the British area took place, and the Scandinavian plants, together with northern insects, birds, and quadrupeds, retreated into the higher grounds. Judging from the evidence at present before us, the first appearance of Man, when, together with the mammoth and woolly rhinoceros, or with the Elephas antiquus, Rhinoceros hemitoechus, and Hippopotamus major, he ranged freely from all parts of the Continent into the British area, took place during this second continental period. Fourthly, the next and last change comprised the breaking up of the land of the British area once more into numerous islands, ending in the present geographical condition of things. There were probably many oscillations of level during this last conversion of continuous land into islands, and such movements in opposite directions would account for the occurrence of marine shells at moderate heights above the level of the sea, notwithstanding a general lowering of the land. To the close of this era belong the marine deposits of the Clyde and the Carses of the Tay and Forth, before alluded to. In a memoir by Professor E. Forbes, before cited, he observes, that the land of passage by which the plants and animals migrated into Ireland consisted of the upraised marine drift which had previously formed the bottom of the glacial sea. Portions of this drift extend to the eastern shores of Wicklow and Wexford, others are found in the Isle of Man full of arctic shells, others on the British coast opposite Ireland. The freshwater marl, containing numerous skeletons of the great deer, or Megaceros, overlie in the Isle of Man that marine glacial drift. Professor Forbes also remarks that the subsequent disjunction of Ireland from England, or the formation of the Irish Channel, which is less than 400 feet in its greatest depth, preceded the opening of the Straits of Dover, or the final separation of England from the Continent. This he inferred from the present distribution of species both in the animal and vegetable kingdoms. Thus, for example, there are twice as many reptiles in Belgium as in England, and the number inhabiting England is twice that found in Ireland. Yet the Irish species are all common to England, and all the English to Belgium. It is therefore assumed that the migration of species westward having been the work of time, there was not sufficient lapse of ages to complete the fusion of the continental and British reptilian fauna, before France was separated from England and England from Ireland. For the same reason there are also a great number of birds of short flight, and small quadrupeds, inhabiting England which do not cross to Ireland, the Irish Channel seeming to have arrested them in their westward course.* (* E. Forbes, Fauna and Flora of British Isles, "Memoir of the Geological Survey" volume 1 1846 page 344.) The depth of the Irish Channel in the narrower parts is only 360 feet, and the English Channel between Dover and Calais less than 200, and rarely anywhere more than 300 feet; so that vertical movements of slight amount compared to some of those previously considered, with the aid of denuding operations or the waste of sea cliffs, and the scouring out of the channel, might in time effect the insulation of the lands above alluded to. TIME REQUIRED FOR SUCCESSIVE CHANGES IN PHYSICAL GEOGRAPHY IN THE PLEISTOCENE PERIOD. The time which it would require to bring about such changes of level, according to the average rate assumed in Chapter 3, however vast, will not be found to exceed that which would best explain the successive fluctuations in terrestrial temperature, the glaciation of solid rocks, the transportation of erratics above and below the sea-level, the height of arctic shells above the sea, and last, not least, the migration of the existing species of animals and plants into their actual stations, and the extinction of some conspicuous forms which flourished during the Pleistocene ages. When we duly consider all these changes which have taken place since the beginning of the glacial epoch, or since the forest of Cromer and the Elephas meridionalis flourished, we shall find that the phenomena become more and more intelligible in proportion to the slowness of the rate of elevation and depression which we assume. The submergence of Wales to the extent of 1400 feet, as proved by glacial shells, would require 56,000 years, at the rate of 2 1/2 feet per century; but taking Professor Ramsay's estimate of 800 feet more, that depression being implied by the position of some of the stratified drift, we must demand an additional period of 32,000 years, amounting in all to 88,000; and the same time would be required for the re-elevation of the tract to its present height. But if the land rose in the second continental period as much as 600 feet above its present level, as in Figure 41, this 600 feet, first of rising and then of sinking, would require 48,000 years more; the whole of the grand oscillation, comprising the submergence and re-emergence, having taken about 224,000 years for its completion; and this, even if there were no pause or stationary period, when the downward movement ceased, and before it was converted into an upward one. I am aware that it may be objected that the average rate here proposed is a purely arbitrary and conjectural one, because, at the North Cape, it is supposed that there has been a rise of about 5 feet in a century, and at Spitsbergen, according to Mr. Lamont, a still faster upheaval during the last 400 years.* (* "Seasons with the Sea-Horses" page 202.) But, granting that in these and some exceptional cases (none of them as yet very well established) the rising or sinking has, for a time, been accelerated, I do not believe the average rate of motion to exceed that above proposed. Mr. Darwin, I find, considers that such a mean rate of upheaval would be as high as we could assume for the west coast of South America, where we have more evidence of sudden changes of level than anywhere else. He has not, however, attempted to estimate the probable rate of secular elevation in that or any other region. Little progress has yet been made in divining the most probable causes of these great movements of the earth's crust; yet what little we know of the state of the interior leads us to expect that the gradual expansion or contraction of large portions of the solid crust may be the result of fluctuations in temperature, with which the existence of hundreds of active and thousands of extinct volcanoes is probably connected. It is ascertained that solid rocks, such as granite and sandstone, expand and contract annually, even under such a moderate range of temperature as that of a Canadian winter and summer. If the heat should go on increasing through a thickness, say only of 10 miles of the earth's crust, the gradual upheaval of the incumbent mass may amount to many hundreds of feet; and the elevation may be carried still farther, by the complete fusion of part of the inferior rocks. According to the experiments of Deville, the contraction of granite, in passing from a melted, or as some would say its plastic condition, to a solid state, must be more than 10 per cent.* (* "Bull. Societe Geologique France" 2nd series volume 4 page 1312.) So that we have at our command a source of depression on a grand scale, at every period when granitic rocks have originated in the interior of the earth's crust. All mineralogists are agreed that the passage of voluminous masses, from a liquid or pasty to a solid and crystalline state, must be an extremely slow process. It may often happen that, in the same series of superimposed rocks, some are expanding while still solid or while partially melting, while others are at the same time crystallising and contracting; so that the alterations of level at the surface may be the result of complicated and often of conflicting agencies. The more gradually we conceive such changes to take place, the more comprehensible they become in the eyes of the chemist and natural philosopher who speculates on the changes of the earth's interior; and the more fertile are they in the hands of the geologist in accounting for revolutions on the habitable surface. We may presume, that after the movement has gone on for a long time in one determinate direction, whether of elevation or depression, the change to an opposite movement, implying the substitution of a heating for a refrigerating operation, or the reverse, would not take place suddenly; but would be marked by a period of inaction, or of slight movement, or such a state of quiescence, as prevails throughout large areas of dry land in the normal condition of the globe. I see no reason for supposing that any part of the revolutions in physical geography, to which the maps above described have reference, indicate any catastrophes greater than those which the present generation has witnessed. If Man was in existence when the Cromer forest was becoming submerged, he would have felt no more alarm than the Danish settlers on the east coast of Baffin's Bay, when they found the poles, which they had driven into the beach to secure their boats, had subsided below their original level. Already, perhaps, the melting ice has thrown down till and boulders upon those poles, a counterpart of the boulder clay which overlies the forest-bed on the Norfolk cliffs. We have seen that all the plants and shells, marine and freshwater, of the forest bed, and associated fluvio-marine strata of Norfolk, are specifically identical with those of the living European flora and fauna; so that if upon such a stratum a deposit of the present period, whether freshwater or marine, should be thrown down, it might lie conformably over it, and contain the same invertebrate fauna and flora. The strata so superimposed would, in ordinary geological language, be called contemporaneous, not only as belonging to the same epoch, but as appertaining strictly to the same subdivision of one and the same epoch; although they would in fact have been separated by an interval of several hundred thousand years. If, in the lower of the two formations, some of the mammalia of the genera elephant and rhinoceros were found to be distinct in species from those of the same genera in the upper or "recent" stratum, it might appear as though there had been a sudden coming in of new forms, and a sudden dying out of old ones; for there would not have been time in the interval for any perceptible change in the invertebrate fauna, by which alone we usually measure the lapse of time in the older formations. When we are contrasting the vertebrate contents of two sets of superimposed strata of the Cretaceous, Oolitic, or any other ancient formation in which the shells are identical in species, we ought never to lose sight of the possibility of their having been separated by such intervals or by two or three thousand centuries. That number of years may sometimes be of small moment in reference to the rate of fluctuation of species in the lower animals, but very important when the succession of forms in the highest classes of vertebrata is concerned. If we reflect on the long series of events of the Pleistocene and Recent periods contemplated in this chapter, it will be remarked that the time assigned to the first appearance of Man, so far as our geological inquiries have yet gone, is extremely modern in relation to the age of the existing fauna and flora, or even to the time when most of the living species of animals and plants attained their actual geographical distribution. At the same time it will also be seen, that if the advent of Man in Europe occurred before the close of the second continental period, and antecedently to the separation of Ireland from England and of England from the Continent, the event would be sufficiently remote to cause the historical period to appear quite insignificant in duration, when compared to the antiquity of the human race. CHAPTER 15. -- EXTINCT GLACIERS OF THE ALPS AND THEIR CHRONOLOGICAL RELATION TO THE HUMAN PERIOD. Extinct Glaciers of Switzerland. Alpine Erratic Blocks on the Jura. Not transported by floating Ice. Extinct Glaciers of the Italian Side of the Alps. Theory of the Origin of Lake-Basins by the erosive Action of Glaciers considered. Successive phases in the Development of Glacial Action in the Alps. Probable Relation of these to the earliest known Date of Man. Correspondence of the same with successive Changes in the Glacial Condition of the Scandinavian and British Mountains. Cold Period in Sicily and Syria. EXTINCT GLACIERS OF SWITZERLAND. We have seen in the preceding chapters that the mountains of Scandinavia, Scotland, and North Wales have served, during the glacial period, as so many independent centres for the dispersion of erratic blocks, just as at present the ice-covered continent of North Greenland is sending down ice in all directions to the coast, and filling Baffin's Bay with floating bergs, many of them laden with fragments of rocks. Another great European centre of ice-action during the Pleistocene period was the Alps of Switzerland, and I shall now proceed to consider the chronological relations of the extinct Alpine glaciers to those of more northern countries previously treated of. [32] The Alps lie far south of the limits of the northern drift described in the foregoing pages, being situated between the 44th and 47th degrees of north latitude. On the flanks of these mountains, and on the sub-Alpine ranges of hills or plains adjoining them, those appearances which have been so often alluded to, as distinguishing or accompanying the drift, between the 50th and 70th parallels of north latitude, suddenly reappear and assume, in a southern region, a truly arctic development. Where the Alps are highest, the largest erratic blocks have been sent forth; as, for example, from the regions of Mont Blanc and Monte Rosa, into the adjoining parts of Switzerland and Italy; while in districts where the great chain sinks in altitude, as in Carinthia, Carniola, and elsewhere, no such rocky fragments, or a few only and of smaller bulk, have been detached and transported to a distance. In the year 1821, M. Venetz first announced his opinion that the Alpine glaciers must formerly have extended far beyond their present limits, and the proofs appealed to by him in confirmation of this doctrine were afterwards acknowledged by M. Charpentier, who strengthened them by new observations and arguments, and declared in 1836 his conviction that the glaciers of the Alps must once have reached as far as the Jura, and have carried thither their moraines across the great valley of Switzerland. M. Agassiz, after several excursions in the Alps with M. Charpentier, and after devoting himself some years to the study of glaciers, published in 1840 an admirable description of them and of the marks which attest the former action of great masses of ice over the entire surface of the Alps and the surrounding country.* (* Agassiz, "Etudes sur les Glaciers et Systeme Glaciaire.") He pointed out that the surface of every large glacier is strewed over with gravel and stones detached from the surrounding precipices by frost, rain, lightning, or avalanches. And he described more carefully than preceding writers the long lines of these stones, which settle on the sides of the glacier, and are called the lateral moraines; those found at the lower end of the ice being called terminal moraines. Such heaps of earth and boulders every glacier pushes before it when advancing, and leaves behind it when retreating. When the Alpine glacier reaches a lower and a warmer situation, about 3000 or 4000 feet above the sea, it melts so rapidly that, in spite of the downward movement of the mass, it can advance no farther. Its precise limits are variable from year to year, and still more so from century to century; one example being on record of a recession of half a mile in a single year. We also learn from M. Venetz, that whereas, between the eleventh and fifteenth centuries, all the Alpine glaciers were less advanced than now, they began in the seventeenth and eighteenth centuries to push forward, so as to cover roads formerly open, and to overwhelm forests of ancient growth. These oscillations enable the geologist to note the marks which a glacier leaves behind it as it retrogrades; and among these the most prominent, as before stated, are the terminal moraines, or mounds of unstratified earth and stones, often divided by subsequent floods into hillocks, which cross the valley like ancient earthworks, or embankments made to dam up a river. Some of these transverse barriers were formerly pointed out by Saussure below the glacier of the Rhone, as proving how far it had once transgressed its present boundaries. On these moraines we see many large angular fragments, which, having been carried along the surface of the ice, have not had their edges worn off by friction; but the greater number of the boulders, even those of large size, have been well rounded, not by the power of water, but by the mechanical force of the ice, which has pushed them against each other, or against the rocks flanking the valley. Others have fallen down the numerous fissures which intersect the glacier, where, being subject to the pressure of the whole mass of ice, they have been forced along, and either well rounded or ground down into sand, or even the finest mud, of which the moraine is largely constituted. As the terminal moraines are the most prominent of all the monuments left by a receding glacier, so are they the most liable to obliteration; for violent floods or debacles are sometimes occasioned in the Alps by the sudden bursting of glacier-lakes, or those temporary sheets of water before alluded to which are caused by the damming up of a river by a glacier which has increased during a succession of cold seasons, and descending from a tributary into the main valley, has crossed it from side to side. On the failure of this icy barrier the accumulated waters, being let loose, sweep away and level many a transverse mound of gravel and loose boulders below, and spread their materials in confused and irregular beds over the river-plain. Another mark of the former action of glaciers in situations where they exist no longer, is the polished, striated, and grooved surfaces of rocks before described. Stones which lie underneath the glacier and are pushed along by it sometimes adhere to the ice, and as the mass glides slowly along at the rate of a few inches, or at the utmost 2 or 3 feet per day, abrade, groove, and polish the rock, and the larger blocks are reciprocally grooved and polished by the rock on their lower sides. As the forces both of pressure and propulsion are enormous, the sand acting like emery polishes the surface; the pebbles, like coarse gravers, scratch and furrow it; and the large stones scoop out grooves in it. Lastly, projecting eminences of rock, called "roches moutonnees," are smoothed and worn into the shape of flattened domes where the glaciers have passed over them. Although the surface of almost every kind of rock when exposed to the open air wastes away by decomposition, yet some retain for ages their polished and furrowed exterior: and if they are well protected by a covering of clay or turf, these marks of abrasion seem capable of enduring for ever. They have been traced in the Alps to great heights above the present glaciers, and to great horizontal distances beyond them. Another effect of a glacier is to lodge a ring of stones round the summit of a conical peak which may happen to project through the ice. If the glacier is lowered greatly by melting, these circles of large angular fragments, which are called "perched blocks," are left in a singular situation near the top of a steep hill or pinnacle, the lower parts of which may be destitute of boulders. ALPINE ERRATIC BLOCKS ON THE JURA. Now some or all the marks above enumerated,--the moraines, erratics, polished surfaces, domes, striae, and perched rocks--are observed in the Alps at great heights above the present glaciers and far below their actual extremities; also in the great valley of Switzerland, 50 miles broad; and almost everywhere on the Jura, a chain which lies to the north of this valley. The average height of the Jura is about one-third that of the Alps, and it is now entirely destitute of glaciers; yet it presents almost everywhere moraines, and polished and grooved surfaces of rocks. The erratics, moreover, which cover it present a phenomenon which has astonished and perplexed the geologist for more than half a century. No conclusion can be more incontestable than that these angular blocks of granite, gneiss, and other crystalline formations, came from the Alps, and that they have been brought for a distance of 50 miles and upwards across one of the widest and deepest valleys of the world; so that they are now lodged on the hills and valleys of a chain composed of limestone and other formations, altogether distinct from those of the Alps. Their great size and angularity, after a journey of so many leagues, has justly excited wonder, for hundreds of them are as large as cottages; and one in particular, composed of gneiss, celebrated under the name of Pierre a Bot, rests on the side of a hill about 900 feet above the lake of Neufchatel, and is no less than 40 feet in diameter. But there are some far-transported masses of granite and gneiss which are still larger, and which have been found to contain 50,000 and 60,000 cubic feet of stone; and one limestone block at Devens, near Bex, which has travelled 30 miles, contains 161,000 cubic feet, its angles being sharp and unworn. Von Buch, Escher, and Studer inferred, from an examination of the mineral composition of the boulders, that those resting on the Jura, opposite the lakes of Geneva and Neufchatel, have come from the region of Mont Blanc and the Valais, as if they had followed the course of the Rhone to the lake of Geneva, and had then pursued their way uninterruptedly in a northerly direction. M. Charpentier, who conceived the Alps in the period of greatest cold to have been higher by several thousand feet than they are now, had already suggested that the Alpine glaciers once reached continuously to the Jura, conveying thither the large erratics in question.* (* D'Archiac, "Histoire des Progres" etc. volume 2 page 249.) M. Agassiz, on the other hand, instead of introducing distinct and separate glaciers, imagined that the whole valley of Switzerland might have been filled with ice, and that one great sheet of it extended from the Alps to the Jura, the two chains being of the same height as now relatively to each other. To this idea it was objected that the difference of altitude, when distributed over a space of 50 miles, would give an inclination of two degrees only, or far less than that of any known glacier. In spite of this difficulty, the hypothesis has since received the support of Professor James Forbes in his very able work on the Alps published in 1843. In 1841, I advanced jointly with Mr. Darwin* the theory that the erratics may have been transferred by floating ice to the Jura, at the time when the greater part of that chain and the whole of the Swiss valley to the south was under the sea. (* See "Elements of Geology" 2nd edition 1841.) We pointed out that if at that period the Alps had attained only half their present altitude they would yet have constituted a chain as lofty as the Chilean Andes, which in a latitude corresponding to Switzerland now send down glaciers to the head of every sound, from which icebergs covered with blocks of granite are floated seaward. Opposite that part of Chile where the glaciers abound is situated the island of Chiloe 100 miles in length with a breadth of 30 miles, running parallel to the continent. The channel which separates it from the main land is of considerable depth and 25 miles broad. Parts of its surface, like the adjacent coast of Chile, are overspread with Recent marine shells, showing an upheaval of the land during a very modern period; and beneath these shells is a boulder deposit in which Mr. Darwin found large blocks of granite and syenite which had evidently come from the Andes. A continuance in future of the elevatory movement now observed to be going on in this region of the Andes and of Chiloe might cause the former chain to rival the Alps in altitude and give to Chiloe a height equal to that of the Jura. The same rise might dry up the channel between Chiloe and the main land so that it would then represent the great valley of Switzerland. Sir Roderick I. Murchison, after making several important geological surveys of the Alps, proposed in 1849 a theory agreeing essentially with that suggested by Mr. Darwin and myself, namely that the erratics were transported to the Jura at a time when the great strath of Switzerland and many valleys receding far into the Alps were under water. He thought it impossible that the glacial detritus of the Rhone could ever have been carried to the Lake of Geneva and beyond it by a glacier, or that so vast a body of ice issuing from one narrow valley could have spread its erratics over the low country of the cantons of Vaud, Fribourg, Berne, and Soleure, as well as the slopes of the Jura, comprising a region of about 100 miles in breadth from south-west to north-east, as laid down in the map of Charpentier. He therefore imagined the granitic blocks to have been translated to the Jura by ice-floats when the intermediate country was submerged.* (* "Quarterly Journal of the Geological Society" volume 6 1850 page 65.) It may be remarked that this theory, provided the water be assumed to have been salt or brackish, demands quite as great an oscillation in the level of the land as that on which Charpentier had speculated, the only difference being that the one hypothesis requires us to begin with a subsidence of 2500 or 3000 feet, and the other with an elevation to the same amount. We should also remember that the crests or watersheds of the Alps and Jura are about 80 miles apart, and if once we suppose them to have been in movement during the glacial period it is very probable that the movements at such a distance may not have been strictly uniform. If so the Alps may have been relatively somewhat higher, which would have greatly facilitated the extension of Alpine glaciers to the flanks of the less elevated chain. Five years before the publication of the memoir last mentioned, M. Guyot had brought forward a great body of new facts in support of the original doctrine of Charpentier, that the Alpine glaciers once reached as far as the Jura and that they had deposited thereon a portion of their moraines.* (* "Bulletin de la Societe des Sciences Naturelles de Neufchatel" 1845.) The scope of his observations and argument was laid with great clearness before the British public in 1852 by Mr. Charles Maclaren, who had himself visited Switzerland for the sake of forming an independent opinion on a theoretical question of so much interest and on which so many eminent men of science had come to such opposite conclusions.* (* "Edinburgh New Philosophical Magazine" October 1852.) M. Guyot had endeavoured to show that the Alpine erratics, instead of being scattered at random over the Jura and the great plain of Switzerland, are arranged in a certain determinate order strictly analogous to that which ought to prevail if they had once constituted the lateral, medial, and terminal moraines of great glaciers. The rocks chiefly relied on as evidence of this distribution consist of three varieties of granite, besides gneiss, chlorite-slate, euphotide, serpentine, and a peculiar kind of conglomerate, all of them foreign alike to the great Strath between the Alps and Jura and to the structure of the Jura itself. In these two regions limestones, sandstones, and clays of the Secondary and Tertiary formations alone crop out at the surface, so that the travelled fragments of Alpine origin can easily be distinguished and in some cases the precise localities pointed out from whence they must have come. [Illustration: Figure 42. Map of Ancient Glacier] (FIGURE 42. MAP SHOWING THE SUPPOSED COURSE OF THE ANCIENT AND NOW EXTINCT GLACIER OF THE RHONE, AND THE DISTRIBUTION OF THE ERRATIC BLOCKS AND DRIFT CONVEYED BY IT TO THE GREAT VALLEY OF SWITZERLAND AND THE JURA.) The accompanying map or diagram (Figure 42) slightly altered from one given by Mr. Maclaren will enable the reader more fully to appreciate the line of argument relied on by M. Guyot. The dotted area is that over which the Alpine fragments were spread by the supposed extinct glacier of the Rhone. The site of the present reduced glacier of that name is shown at A. From that point the boulders may first be traced to B, or Martigny, where the valley takes an abrupt turn at right angles to its former course. Here the blocks belonging to the right side of the river or derived from c d e have not crossed over to the left side at B, as they should have done had they been transported by floating ice, but continue to keep to the side to which they belonged, assuming that they once formed part of a right lateral moraine of a great extinct glacier. That glacier, after arriving at the lower end of the long narrow valley of the upper Rhone at F, filled the Lake of Geneva, F, I, with ice. From F, as from a great vomitory, it then radiated in all directions bearing along with it the moraines with which it was loaded and spreading them out on all sides over the great plain. But the principal icy mass moved straight onwards in a direct line towards the hill of Chasseron, G (precisely opposite F), where the Alpine erratics attain their maximum of height on the Jura, that is to say 2015 English feet above the level of the Lake of Neufchatel or 3450 feet above the sea. The granite blocks which have ascended to this eminence G came from the east shoulder of Mont Blanc h, having travelled in the direction B, F, G. When these and the accompanying blocks resting on the south-eastern declivity of the Jura are traced from their culminating point G in opposite directions, whether westward towards Geneva or eastwards towards Soleure, they are found to decline in height from the middle of the arc G towards the two extremities I and K, both of which are at a lower level than G, by about 1500 feet. In other words the ice of the extinct glacier, having mounted up on the sloping flanks of the Jura in the line of greatest pressure to its highest elevation, began to decline laterally in the manner of a pliant or viscous mass with a gentle inclination till it reached two points distant from each other no less than 100 miles. [33] In further confirmation of this theory M. Guyot observed that fragments derived from the right bank of the great valley of the Rhone c d e are found on the right side of the great Swiss basin or Strath as at l and m, while those derived from the left bank p h occur on the left side of the basin or on the Jura between G and I; and those again derived from places farthest up on the left bank and nearest the source of the Rhone, as n o, occupy the middle of the great basin, constituting between m and K what M. Guyot calls the frontal or terminal moraine of the eastern prolongation of the old glacier. A huge boulder of talcose granite, now at Steinhoff, 10 miles east from K, or Soleure, containing 61,000 French cubic feet, or equal in bulk to a mass measuring 40 feet in every direction, was ascertained by Charpentier from its composition to have been derived from n, one of the highest points on the left side of the Rhone valley far above Martigny. From this spot it must have gone all round by F, which is the only outlet to the deep valley, so as to have performed a journey of no less than 150 miles! GENERAL TRANSPORTATION OF ERRATICS IN SWITZERLAND DUE TO GLACIERS AND NOT TO FLOATING ICE. It is evident that the above described restriction of certain fragments of peculiar lithological character to that bank of the Rhone where the parent rocks are alone met with and the linear arrangement of the blocks in corresponding order on the opposite side of the great plain of Switzerland, are facts which harmonise singularly well with the theory of glaciers while they are wholly irreconcilable with that of floating ice. Against the latter hypothesis all the arguments which Charpentier originally brought forward in opposition to the first popular doctrine of a grand debacle or sudden flood rushing down from the Alps to the Jura might be revived. Had there ever been such a rush of muddy water, said he, the blocks carried down the basins of the principal Swiss rivers, such as the Rhone, Aar, Reuss, and Limmat, would all have been mingled confusedly together instead of having each remained in separate and distinct areas as they do and should do according to the glacial hypothesis. M. Morlot presented me in 1857 with an unpublished map of Switzerland in which he had embodied the results of his own observations and those of MM. Guyot, Escher, and others, marking out by distinct colours the limits of the ice-transported detritus proper to each of the great river-basins. The arrangement of the drift and erratics thus depicted accords perfectly well with Charpentier's views and is quite irreconcilable with the supposition of the scattered blocks having been dispersed by floating ice when Switzerland was submerged. As opposed to the latter hypothesis, I may also state that nowhere as yet have any marine shells or other fossils than those of a terrestrial character, such as the bones of the mammoth and a few other mammalia and some coniferous wood, been detected in those drifts, though they are often many hundreds of feet in thickness. A glance at M. Morlot's map, above mentioned,* will show that the two largest areas, indicated by a single colour, are those over which the Rhone and the Rhine are supposed to have spread out in ancient times their enormous moraines. (* See map, "Quarterly Journal of the Geological Society" volume 18 1862 page 185 Plate 18.) One of these only, that of the Rhone, has been exhibited in our diagram, Figure 42. The distinct character of the drift in the two cases is such as it would be if two colossal glaciers should now come down from the higher Alps through the valleys traversed by those rivers, leaving their moraines in the low country. The space occupied by the glacial drift of the Rhine is equal in dimensions or rather exceeds that of the Rhone, and its course is not interfered with in the least degree by the Lake of Constance, 45 miles long, any more than is the dispersion of the erratics of the Rhone by the Lake of Geneva, about 50 miles in length. The angular and other blocks have in both instances travelled on precisely as if those lakes had no existence, or as if, which was no doubt the case, they had been filled with solid ice. During my last visit to Switzerland in 1857, I made excursions, in company with several distinguished geologists, for the sake of testing the relative merits of the two rival theories above referred to, and I examined parts of the Jura above Neufchatel in company with M. Desor, the country round Soleure with M. Langen, the southern side of the great strath near Lausanne with M. Morlot, the basin of the Aar around Berne with M. Escher von der Linth; and having satisfied myself that all the facts which I saw north of the Alps were in accordance with M. Guyot's views, I crossed to the Italian side of the great chain and became convinced that the same theory was equally applicable to the ancient moraines of the plains of the Po. M. Escher pointed out to me at Trogen in Appenzel on the left bank of the Rhine fragments of a rock of a peculiar mineralogical character, commonly called the granite of Pontelyas, the natural position of which is well known near Trons, 100 miles from Trogen, on the left bank of the Rhine about 30 miles from the source of that river. All the blocks of this peculiar granite keep to the left bank, even where the valley turns almost at right angles to its former course near Mayenfeld below Chur, making a sharp bend resembling that of the valley of the Rhone at Martigny. The granite blocks, where they are traced to the low country, still keep to the left side of the Lake of Constance. That they should not have crossed over to the opposite river-bank below Chur is quite inexplicable if, rejecting the aid of land-ice, we appeal to floating ice as the transporting power. In M. Morlot's map already cited we behold between the areas occupied by the glacial drift of the Rhine and Rhone three smaller yet not inconsiderable spaces distinguished by distinct colours, indicating the peculiar detritus brought down by the three great rivers, the Aar, Reuss, and Limmat. The ancient glacier of the first of these, the Aar, has traversed the lakes of Brienz and Thun and has borne angular, polished, and striated blocks of limestone and other rocks as far as Berne and somewhat below that city. The Reuss has also stamped the lithological character of its own mountainous region upon the lower part of its hydrographical basin by covering it with its peculiar Alpine drift. In like manner the old extinct glacier of the Limmat during its gradual retreat has left monuments of its course in the Lake of Zurich in the shape of terminal moraines, one of which has almost divided that great sheet of water into two lakes. The ice-work done by the extinct glaciers, as contrasted with that performed by their dwarfed representatives of the present day, is in due proportion to the relative volume of the supposed glaciers, whether we measure them by the distances to which they have carried erratic blocks or the areas which they have strewed over with drift or the hard surfaces of rock and number of boulders which they have polished and striated. Instead of a length of 5, 10, or 20 miles and a thickness of 200, 300, or at the utmost 800 feet, those giants of the olden time must have been from 50 to 150 miles long and between 1000 and 3000 feet deep. In like manner the glaciation although identical in kind is on so small a scale in the existing Alpine glaciers as at first sight to disappoint a Swedish, Scotch, Welsh, or North American geologist. When I visited the terminal moraine of the glacier of the Rhone in 1859 and tried to estimate the number of angular or rounded pebbles and blocks which exhibited glacial polishing or scratches as compared to those bearing no such markings, I found that several thousand had to be reckoned before I arrived at the first which was so striated or polished as to differ from the stones of an ordinary torrent-bed. Even in the moraines of the glaciers of Zermatt, Viesch, and others, in which fragments of limestone and serpentine are abundant (rocks which most readily receive and most faithfully retain the signs of glaciation), I found, for one which displayed such indications, several hundreds entirely free from them. Of the most opposite character were the results obtained by me from a similar scrutiny of the boulders and pebbles of the terminal moraine of one of the old extinct glaciers, namely, that of the Rhone in the suburbs of Soleure. Thus at the point K in the map, Figure 42, I observed a mass of unstratified clay or mud, through which a variety of angular and rubbed stones were scattered and a marked proportion of the whole were polished and scratched and the clay rendered so compact, as if by the incumbent pressure of a great mass of ice, that it has been found necessary to blow it up with gunpowder in making railway cuttings through part of it. A limestone of the age of our Portland stone on which this old moraine rests, has its surface polished like a looking-glass, displaying beautiful sections of fossil shells of the genera Nerinaea and Pteroceras, while occasionally, besides finer striae, there are deep rectilinear grooves, agreeing in direction with the course in which the extinct glacier would have moved according to the theory of M. Guyot, before explained. EXTINCT GLACIERS OF THE ITALIAN SIDE OF THE ALPS. [Illustration: Figure 43. Map Of The Moraines Of Extinct Glaciers] (FIGURE 43. MAP OF THE MORAINES OF EXTINCT GLACIERS EXTENDING FROM THE ALPS INTO THE PLAINS OF THE PO NEAR TURIN. From Map of the ancient Glaciers of the Italian side of the Alps by Signor Gabriel de Mortillet. A. Crest or watershed of the Alps. B. Snow-covered Alpine summits which fed the ancient glaciers. C. Moraines of ancient or extinct glaciers.) To select another example from the opposite or southern side of the Alps. It will be seen in the elaborate map recently executed by Signor Gabriel de Mortillet of the ancient glaciers of the Italian flank of the Alps that the old moraines descend in narrow strips from the snow-covered ridges through the principal valleys to the great basin of the Po, on reaching which they expand and cover large circular or oval areas. Each of these groups of detritus is observed (see map, Figure 43) to contain exclusively the wreck of such rocks as occur in situ on the Alpine heights of the hydrographical basins to which the moraines respectively belong. I had an opportunity of verifying this fact, in company with Signor Gastaldi as my guide, by examining the erratics and boulder formation between Susa and Turin, on the banks of the Dora Riparia, which brings down the waters from Mont Cenis and from the Alps south-west of it. I there observed striated fragments of dolomite and gypsum, which had come down from Mont Cenis and had travelled as far as Avigliana; also masses of serpentine brought from less remote points, some of them apparently exceeding in dimensions the largest erratics of Switzerland. I afterwards visited, in company with Signori Gastaldi and Michelotti, a still grander display of the work of a colossal glacier of the olden time, 20 miles north-east of Turin, the moraine of which descended from the two highest of the Alps, Mont Blanc and Monte Rosa, and after passing through the valley of Aosta, issued from a narrow defile above Ivrea (see map, Figure 43). From this vomitory the old glacier poured into the plains of the Po that wonderful accumulation of mud, gravel, boulders, and large erratics, which extend for 15 miles from above Ivrea to below Caluso and which when seen in profile from Turin have the aspect of a chain of hills. In many countries, indeed, they might rank as an important range of hills, for where they join the mountains they are more than 1500 feet high, and retain more than half that height for a great part of their course, rising very abruptly from the plain, often with a slope of from 20 to 30 degrees. This glacial drift reposes near the mountains on ancient metamorphic rocks and farther from them on marine Pliocene strata. Portions of the ridges of till and stratified matter have been cut up into mounds and hillocks by the action of the river, the Dora Baltea, and there are numerous lakes, so that the entire moraine much resembles, except in its greater height and width, the line of glacial drift of Perthshire and Forfarshire before described. Its complicated structure can only be explained by supposing that the ancient glacier advanced and retreated several times and left large lateral moraines, the more modern mounds within the limits of the older ones, and masses of till thrown down upon the rearranged and stratified materials of the first set of moraines. Such appearances accord well with the hypothesis of the successive phases of glacial action in Switzerland, to which I shall presently advert. CONTORTED STRATA OF GLACIAL DRIFT SOUTH OF IVREA. At Mazze near Caluso (see Figure 43), the southern extremity of this great moraine has recently been cut through in making a tunnel for the railway which runs from Turin to Ivrea. In the fine section thus exposed Signor Gastaldi and I had an opportunity of observing the internal structure of the glacial formation. In close juxtaposition to a great mass of till with striated boulders, we saw stratified beds of alternating gravel, sand, and loam, which were so sharply bent that many of them had been twice pierced through in the same vertical cutting. Whether they had been thus folded by the mechanical power of an advancing glacier, which had pushed before it a heap of stratified matter, as the glacier of Zermatt has been sometimes known to shove forward blocks of stone through the walls of houses, or whether the melting of masses of ice, once interstratified with sand and gravel, had given rise to flexures in the manner before suggested; it is at least satisfactory to have detected this new proof of a close connection between ice-action and contorted stratification, such as has been described as so common in the Norfolk cliffs and which is also very often seen in Scotland and North America, where stratified gravel overlies till. I have little doubt that if the marine Pliocene strata which underlie a great part of the moraine below Ivrea were exposed to view in a vertical section, those fundamental strata would be found not to participate in the least degree in the plications of the sands and gravels of the overlying glacial drift. To return to the marks of glaciation: in the moraine at Mazze there are many large blocks of protogine and large and small ones of limestone and serpentine which have been brought down from Monte Rosa, through the gorge of Ivrea, after having travelled for a distance of 50 miles. Confining my attention to a part of the moraine where pieces of limestone and serpentine were very numerous, I found that no less than one-third of the whole number bore unequivocal signs of glacial action; a state of things which seems to bear some relation to the vast volume and pressure of the ice which once constituted the extinct glacier and to the distance which the stones had travelled. When I separated the pebbles of quartz, which were never striated, and those of granite, mica-schist, and diorite, which do not often exhibit glacial markings, and confined my attention to the serpentine alone I found no less than nineteen in twenty of the whole number polished and scratched; whereas in the terminal moraines of some modern glaciers, where the materials have travelled not more than 10 or 15, instead of 100 miles, scarce one in twenty even of the serpentine pebbles exhibit glacial polish and striation. THEORY OF THE ORIGIN OF LAKE-BASINS BY THE EROSIVE ACTION OF GLACIERS, CONSIDERED. Geologists are all agreed that the last series of movements to which the Alps owe their present form and internal structure occurred after the deposition of the Miocene strata; and it has been usual to refer the origin of the numerous lake-basins of Alpine and sub-Alpine regions both in Switzerland and Northern Italy to the same movements; for it seemed not unnatural to suppose, that forces capable of modifying the configuration of the greatest European chain, by uplifting some of its component Tertiary strata (those of marine origin of the Miocene period) several thousand feet above their former level, after throwing them into vertical and contorted positions, must also have given rise to many superficial inequalities, in some of which large bodies of water would collect. M. Desor, in a memoir on the Swiss and Italian lakes, suggested that they may have escaped being obliterated by sedimentary deposition by having been filled with ice during the whole of the glacial period. Subsequently to the retreat of the great glaciers we know that the lake-basins have been to a certain extent encroached upon and turned into land by river deltas; one of which, that of the Rhone at the head of the Lake of Geneva, is no less than 12 miles long and several miles broad, besides which there are many torrents on the borders of the same lake, forming smaller deltas. M. Gabriel de Mortillet after a careful study of the glacial formations of the Alps agreed with his predecessors that the great lakes had existed before the glacial period, but came to the opinion in 1859 that they had all been first filled up with alluvial matter and then re-excavated by the action of ice, which during the epoch of intense cold had by its weight and force of propulsion scooped out the loose and incoherent alluvial strata, even where they had accumulated to a thickness of 2000 feet. Besides this erosion, the ice had carried the whole mass of mud and stones up the inclined planes, from the central depths to the lower outlets of the lakes and sometimes far beyond them. As some of these rock-basins are 500, others more than 2000 feet deep, having their bottoms in some cases 500, in others 1000 feet below the level of the sea, and having areas from 20 to 50 miles in length and from 4 to 12 in breadth, we may well be startled at the boldness of this hypothesis. The following are the facts and train of reasoning which induced M. de Mortillet to embrace these views. At the lower ends of the great Italian lakes, such as Maggiore, Como, Garda, and others, there are vast moraines which are proved by their contents to have come from the upper Alpine valleys above the lakes. Such moraines often repose on an older stratified alluvium, made up of rounded and worn pebbles of precisely the same rocks as those forming the moraines, but not derived from them, being small in size, never angular, polished, or striated, and the whole having evidently come from a great distance. These older alluvial strata must, according to M. de Mortillet, be of pre-glacial date and could not have been carried past the sites of the lakes, unless each basin had previously been filled and levelled up with mud, sand, and gravel, so that the river channel was continuous from the upper to the lower extremity of each basin. Professor Ramsay, after acquiring an intimate knowledge of the glacial phenomena of the British Isles, had taught many years before that small tarns and shallow rock-basins such as we see in many mountain regions owe their origin to glaciers which erode the softer rocks, leaving the harder ones standing out in relief and comparatively unabraded. Following up this idea after he had visited Switzerland and without any communication with M. de Mortillet or cognisance of his views, he suggested in 1859 that the lake-basins were not of pre-glacial date, but had been scooped out by ice during the glacial period, the excavation having for the most part been effected in Miocene sandstone, provincially called, on account of its softness, "molasse." By this theory he dispensed with the necessity of filling up pre-existing cavities with stratified alluvium, in the manner proposed by M. de Mortillet. I will now explain to what extent I agree with, and on what points I feel compelled to differ from the two distinguished geologists above cited. First. It is no doubt true, as Professor Ramsay remarks, that heavy masses of ice, creeping for ages over a surface of dry land (whether this comprise hills, plateaus, and valleys, as in the case of Greenland, before described, or be confined to the bottoms of great valleys, as now in the higher Alps), must often by their grinding action produce depressions, in consequence of the different degrees of resistance offered by rocks of unequal hardness. Thus, for example, where quartzose beds of mica-schist alternate with clay-slate, or where trap-dykes, often causing waterfalls in the courses of torrents, cut through sandstone or slate--these and innumerable other common associations of dissimilar stony compounds must give rise to a very unequal amount of erosion and consequently to lake-basins on a small scale. But the larger the size of any lake, the more certain it will be to contain within it rocks of every degree of hardness, toughness, and softness; and if we find a gradual deepening from the head towards the central parts and a shallowing again from the middle to the lower end, as in several of the great Swiss and Italian lakes, which are 30 or 40 miles in length, we require a power capable of acting with a considerable degree of uniformity on these masses of varying powers of resistance. Secondly. Several of the great lakes are by no means in the line of direction which they ought to have taken had they been scooped out by the pressure and onward movement of the extinct glaciers. The Lake of Geneva, for instance, had it been the work of ice, would have been prolonged from the termination of the upper valley of the Rhone towards the Jura, in the direction from F to G of the map, Figure 42, instead of running from F to I. Thirdly. It has been ascertained experimentally, that in a glacier, as in a river, the rate of motion is accelerated or lessened, according to the greater or less slope of the ground; also, that the lower strata of ice, like those of water, move more slowly than those above them. In the Lago Maggiore, which is more than 2600 feet deep (797 metres), the ice, says Professor Ramsay, had to descend a slope of about 3 degrees for the first 25 miles, and then to ASCEND for the last 12 miles (from the deepest part towards the outlet) at an angle of 5 degrees. It is for those who are conversant with the dynamics of glacier motion to divine whether in such a case the discharge of ice would not be entirely effected by the superior and faster moving strata, and whether the lowest would not be motionless or nearly so, and would therefore exert very little, if any, friction on the bottom. Fourthly. But the gravest objection to the hypothesis of glacial erosion on so stupendous a scale is afforded by the entire absence of lakes of the first magnitude in several areas where they ought to exist if the enormous glaciers which once occupied those spaces had possessed the deep excavating power ascribed to them. Thus in the area laid down on the map, Figure 43, or that covered by the ancient moraine of the Dora Baltea, we see the monuments of a colossal glacier derived from Mont Blanc and Monte Rosa, which descended from points nearly 100 miles distant, and then emerging from the narrow gorge above Ivrea deployed upon the plains of the Po, advancing over a floor of marine Pliocene strata of no greater solidity than the Miocene sandstone and conglomerate in which the lake-basins of Geneva, Zurich, and some others are situated. Why did this glacier fail to scoop out a deep and wide basin rivalling in size the lakes of Maggiore or Como, instead of merely giving rise to a few ponds above Ivrea, which may have been due to ice action? There is one lake, it is true--that of Candia, near the southern extremity of the moraine--which is larger; but even this, as will be seen by the map, is quite of subordinate importance, and whether it is situated in a rock basin or is simply caused by a dam of moraine matter has not yet been fully made out. There ought also to have been another great lake, according to the theory under consideration, in the space now occupied by the moraine of the Dora Riparia, between Susa and Turin (see map, Figure 43). Signor Gastaldi has shown that all the ponds in that area consist exclusively of what M. de Mortillet has denominated morainic lakes, i.e. caused by barriers of glacier-mud and stones. Fifthly. In proof of the great lakes having had no existence before the glacial period, Professor Ramsay observes that we do not find in the Alps any freshwater strata of an age intermediate between "the close of the Miocenic and the commencement of the glacial epoch."* (* "Quarterly Journal of the Geological Society" volume 18 1862.) But although such formations are scarce, they are by no means wholly wanting; and if it can be shown that any one of the principal lakes, that of Zurich for example, existed prior to the glacial era it will follow that in the Alps the erosive power of ice was not required to produce lake-basins on a large scale. The deposits alluded to on the borders of the Lake of Zurich are those of Utznach and Durnten, situated each about 350 feet above the present level of the lake and containing valuable beds of lignite. The first of them, that of Utznach, is a delta formed at the head of the ancient and once more extensive lake. The argillaceous and lignite-bearing strata, more than 100 feet in thickness, rest unconformably on highly inclined and sometimes vertical Miocene molasse. These clays are covered conformably by stratified sand and gravel 60 feet thick, partly consolidated, in which the pebbles are of rocks belonging to the upper valleys of the Limmat and its tributaries, all of them small and not glacially striated and wholly without admixture of large angular stones. On the top of all repose very large erratic blocks, affording clear evidence that the colossal glacier which once filled the valley of the Limmat covered the old littoral deposit. The great age of the lignite is partly indicated by the bones of Elephas antiquus found in it. I visited Utznach in company with M. Escher von der Linth in 1857, and during the same year examined the lignite of Durnten, many miles farther down on the right bank of the lake, in company with Professor Heer and M. Marcou. The beds there are of the same age and within a few feet of the same height above the level of the lake. They might easily have been overlooked or confounded with the general glacial drift of the neighbourhood, had not the bed of lignite, which is from 5 to 12 feet thick, been worked for fuel, during which operation many organic remains came to light. Among these are the teeth of Elephas antiquus, determined by Dr. Falconer, and Rhinoceros leptorhinus? (R. megarhinus, Christol), the wild bull and red deer (Bos primigenius, Boj., and Cervus elaphus, L.), the last two determined by Professor Rutimeyer. In the same beds I found many freshwater shells of the genera Paludina, Limnaea, etc., all of living species. The plants named by Professor Heer are also Recent and agree singularly with those of the Cromer buried forest, before described. Among them are the Scotch and spruce firs, Pinus sylvestris and Pinus abies, and the buckbean, or Menyanthes trifoliata, etc., besides the common birch and other European plants. Overlying this lignite are first, as at Utznach, stratified gravel not of glacial origin, about 30 feet thick; and secondly, highest of all, huge angular erratic blocks clearly indicating the presence of a great glacier posterior in date to all the organic remains above enumerated. If any one of the existing Swiss lakes were now lowered by deepening its outlet, or by raising the higher portion of it relatively to the lower, we should see similar deltas of comparatively modern date exposed to view, some of them with embedded trunks of pines of the same species drifted down during freshets. Such deposits would be most frequent at the upper ends of the lakes, but a few would occur on either bank not far from the shore where torrents once entered, agreeing in geographical position with the lignite formations of Utznach and Durnten. There are other freshwater formations with lignite, besides those on the Lake of Zurich, as those of Wetzikon near the Pfaffikon Lake, of Kaltbrunnen, of Buchberg, and that of Morschweil between St. Gall and Rorschach, but none probably older than the Durnten beds. Like the buried forest of Cromer they are all pre-glacial, yet they by no means represent the older nor even the newer Pliocene period, but rather the beginning of the Pleistocene. It is therefore true, as Professor Ramsay remarks, that, as yet, no strata "of the age of the English Crag" have been detected in any Alpine valley. In other words, there are no freshwater formations yet known corresponding in date to the Pliocene beds of the upper Val d'Arno, above Florence--a fact from which we may infer (though with diffidence, as the inference is based on negative evidence), that, although the great Alpine valleys were eroded in Pliocene times, the lake-basins were, nevertheless, of Pleistocene date--some of them formed before, others during, the glacial epoch. Sixthly. In what manner then did the great lake-basins originate if they were not hollowed out by ice? My answer is, they are all due to unequal movements of upheaval and subsidence. We have already seen that the buried forest of Cromer, which by its organic contents seems clearly to be of the same age as the lignite of Durnten, was pre-glacial and that it has undergone a great oscillation of level (about 500 feet in both directions) since its origin, having first sunk to that extent below the sea and then been raised up again to the sea-level. In the countless Post-Miocene ages which preceded the glacial period there was ample time for the slow erosion by water of all the principal hydrographical basins of the Alps, and the sites of all the great lakes coincide, as Professor Ramsay truly says, with these great lines of drainage. The lake-cavities do not lie in synclinal troughs, following the strike and foldings of the strata, but often, as the same geologist remarks, cross them at high angles; nor are they due to rents or gaping fissures, although these, with other accidents connected with the disturbing movements of the Alps, may sometimes have determined originally the direction of the valleys. The conformity of the lake-basins to the principal watercourses is explicable if we assume them to have resulted from inequalities in the upward and downward movements of the whole country in Pleistocene times, after the valleys were eroded. We know that in Sweden the rate of the rise of the land is far from uniform, being only a few inches in a century near Stockholm, while north of it and beyond Gefle it amounts to as many feet in the same number of years. Let us suppose with Charpentier that the Alps gained in height several thousand feet at the time when the intense cold of the glacial period was coming on. This gradual rise would be an era of aqueous erosion and of the deepening, widening, and lengthening of the valleys. It is very improbable that the elevation would be everywhere identical in quantity, but if it was never in excess in the outskirts as compared to the central region or crest of the chain, it would not give rise to lakes. When, however, the period of upheaval was followed by one of gradual subsidence, the movement not being everywhere strictly uniform, lake-basins would be formed wherever the rate of depression was in excess in the upper country. Let the region, for example, near the head waters of the great rivers sink at the rate of from 4 to 6 feet per century, while only half as much subsidence occurs towards the circumference of the mountains--the rate diminishing about an inch per mile in a distance, say of 40 miles--this might convert many of the largest and deepest valleys at their lower ends into lakes. We have no certainty that such movements may not now be in progress in the Alps; for if they are as slow as we have assumed, they would be as insensible to the inhabitants as is the upheaval of Scandinavia or the subsidence of Greenland to the Swedes and Danes who dwell there. They only know of the progress of such geographical revolutions because a slight change of level becomes manifest on the margin of the sea. The lines of elevation or depression above supposed might leave no clear geological traces of their action on the high ridges and table-lands separating the valleys of the principal rivers; it is only when they cross such valleys that the disturbance caused in the course of thousands of years in the drainage becomes apparent. If there were no ice, the sinking of the land might not give rise to lakes. To accomplish this in the absence of ice, it is necessary that the rate of depression should be sufficiently fast to make it impossible for the depositing power of the river to keep pace with it, or in other words to fill up the incipient cavity as fast as it begins to form. Such levelling operations once complete, the running water, aided by sand and pebbles, will gradually cut a gorge through the newly raised rock so as to prevent it from forming a barrier. But if a great glacier fill the lower part of the valley all the conditions of the problem are altered. Instead of the mud, sand, and stones drifted down from the higher regions being left behind in the incipient basin, they all travel onwards in the shape of moraines on the top of the ice, passing over and beyond the new depression, so that when at the end of fifty or a thousand centuries the glacier melts, a large and deep basin representing the difference in the movement of two adjoining mountain areas--namely, the central and the circumferential--is for the first time rendered visible. By adopting this hypothesis, we concede that there is an intimate connection between the glacial period and a predominance of lakes, in producing which the action of ice is threefold; first, by its direct power in scooping out shallow basins where the rocks are of unequal hardness; an operation which can by no means be confined to the land, for it must extend to below the level of high water a thousand feet and more in such fjords as have been described as filled with ice in Greenland. Secondly. The ice will act indirectly by preventing cavities caused by inequalities of subsidence or elevation from becoming the receptacles first of water and then of sediment, by which the cavities would be levelled up and the lakes obliterated. Thirdly. The ice is also an indirect cause of lakes, by heaping up mounds of moraine matter and thus giving rise to ponds and even to sheets of water several miles in diameter. The comparative scarcity, therefore, of lakes of Pleistocene date in tropical countries, and very generally south of the fortieth and fiftieth parallels of latitude, may be accounted for by the absence of glacial action in such regions. POST-GLACIAL LAKE-DWELLING IN THE NORTH OF ITALY. We learn from M. de Mortillet that in the peat which has filled up one of the "morainic lakes" formed by the ancient glacier of the Ticino, M. Moro has discovered at Mercurago the piles of a lake-dwelling like those of Switzerland, together with various utensils and a canoe hollowed out of the trunk of a tree. From this fact we learn that south of the Alps as well as north of them a primitive people having similar habits flourished after the retreat of the great glaciers. SUCCESSIVE PHASES OF GLACIAL ACTION IN THE ALPS, AND THEIR RELATION TO THE HUMAN PERIOD [34]. According to the geological observations of M. Morlot, the following successive phases in the development of ice-action in the Alps are plainly recognisable:-- First. There was a period when the ice was in its greatest excess, when the glacier of the Rhone not only reached the Jura, but climbed to the height of 2015 feet above the Lake of Neufchatel, and 3450 feet above the sea, at which time the Alpine ice actually entered the French territory at some points, penetrating by certain gorges, as through the defile of the Fort de l'Ecluse, among others. Second. To this succeeded a prolonged retreat of the great glaciers, when they evacuated not only the Jura and the low country between that chain and the Alps, but retired some way back into the Alpine valleys. M. Morlot supposes their diminution in volume to have accompanied a general subsidence of the country to the extent of at least 1000 feet. The geological formations of the second period consist of stratified masses of sand and gravel, called the "ancient alluvium" by MM. Necker and Favre, corresponding to the "older or lower diluvium" of some writers. Their origin is evidently due to the action of rivers, swollen by the melting of ice, by which the materials of parts of the old moraines were rearranged and stratified and left usually at considerable heights above the level of the present valley plains. Third. The glaciers again advanced and became of gigantic dimensions, though they fell far short of those of the first period. That of the Rhone, for example, did not again reach the Jura, though it filled the Lake of Geneva and formed enormous moraines on its borders and in many parts of the valley between the Alps and Jura. Fourth. A second retreat of the glaciers took place when they gradually shrank nearly into their present limits, accompanied by another accumulation of stratified gravels which form in many places a series of terraces above the level of the alluvial plains of the existing rivers. In the gorge of the Dranse, near Thonon, M. Morlot discovered no less than three of these glacial formations in direct superposition, namely, at the bottom of the section, a mass of compact till or boulder-clay (Number 1) 12 feet thick, including striated boulders of Alpine limestone, and covered by regularly stratified ancient alluvium (Number 2) 150 feet thick, made up of rounded pebbles in horizontal beds. This mass is in its turn overlaid by a second formation (Number 3) of unstratified boulder clay, with erratic blocks and striated pebbles, which constituted the left lateral moraine of the great glacier of the Rhone when it advanced for the second time to the Lake of Geneva. At a short distance from the above section terraces (Number 4) composed of stratified alluvium are seen at the heights of 20, 50, 100, and 150 feet above the Lake of Geneva, which by their position can be shown to be posterior in date to the upper boulder-clay and therefore belong to the fourth period, or that of the last retreat of the great glaciers. In the deposits of this fourth period the remains of the mammoth have been discovered, as at Morges, for example, on the Lake of Geneva. The conical delta of the Tiniere, mentioned in Chapter 2 as containing at different depths monuments of the Roman as well as of the antecedent bronze and stone ages, is the work of alluvial deposition going on when the terrace of 50 feet was in progress. This modern delta is supposed by M. Morlot to have required 10,000 years for its accumulation. At the height of 150 feet above the lake, following up the course of the same torrent, we come to a more ancient delta, about ten times as large, which is therefore supposed to be the monument of about ten times as many centuries, or 100,000 years, all referable to the fourth period mentioned in the preceding page, or that which followed the last retreat of the great glaciers.* (* Morlot, Terrain quaternaire du Bassin de Leman "Bulletin de la Societe Vaudoise des Sciences Naturelles" Number 44.) If the lower flattened cone of Tiniere be referred in great part to the age of the oldest lake-dwellings, the higher one might perhaps correspond with the Pleistocene period of St. Acheul, or the era when Man and the Elephas primigenius flourished together; but no human remains or works of art have as yet been found in deposits of this age or in any alluvium containing the bones of extinct mammalia in Switzerland. Upon the whole, it is impossible not to be struck with an apparent correspondence in the succession of events of the glacial period of Switzerland and that of the British Isles before described. The time of the first Alpine glaciers of colossal dimensions, when that chain perhaps was several thousand feet higher than now, may have agreed with the first continental period when Scotland was invested with a universal crust of ice. The retreat of the first Alpine glaciers, caused partly by a lowering of that chain, may have been synchronous with the period of great submergence and floating ice in England. The second advance of the glaciers may have coincided in date with the re-elevation of the Alps, as well as of the Scotch and Welsh mountains; and lastly, the final retreat of the Swiss and Italian glaciers may have taken place when Man and the extinct mammalia were colonising the north-west of Europe and beginning to inhabit areas which had formed the bed of the glacial sea during the era of chief submergence. But it must be confessed that in the present state of our knowledge these attempts to compare the chronological relations of the periods of upheaval and subsidence of areas so widely separated as are the mountains of Scandinavia, the British Isles, and the Alps, or the times of the advance and retreat of glaciers in those several regions and the greater or less intensity of cold, must be looked upon as very conjectural. We may presume with more confidence that when the Alps were highest and the Alpine glaciers most developed, filling all the great lakes of northern Italy and loading the plains of Piedmont and Lombardy with ice, the waters of the Mediterranean were chilled and of a lower average temperature than now. Such a period of refrigeration is required by the conchologist to account for the prevalence of northern shells in the Sicilian seas about the close of the Pliocene or commencement of the Pleistocene period. For such shells as Cyprina islandica, Panopoea norvegica (= P. bivonae, Philippi), Leda pygmaea, Munst, and some others, enumerated among the fossils of the latest Tertiary formations of Sicily by Philippi and Edward Forbes, point unequivocally to a former more severe climate. Dr. Hooker also in his late journey to Syria (in the autumn of 1860) found the moraines of extinct glaciers, on which the whole of the ancient cedars of Lebanon grow, to descend 4000 feet below the summit of that chain. The temperature of Syria is now so much milder that there is no longer perpetual snow even on the summit of Lebanon, the height of which was ascertained to be 10,200 feet above the Mediterranean.* (* Hooker, "Natural History Review" Number 5 January 1862 page 11.) Such monuments of a cold climate in latitudes so far south as Syria and the north of Sicily, between 33 and 38 degrees north, may be confidently referred to an early part of the glacial period, or to times long anterior to those of Man and the extinct mammalia of Abbeville and Amiens. CHAPTER 16. -- HUMAN REMAINS IN THE LOESS, AND THEIR PROBABLE AGE. Nature, Origin, and Age of the Loess of the Rhine and Danube. Impalpable Mud produced by the Grinding Action of Glaciers. Dispersion of this Mud at the Period of the Retreat of the great Alpine Glaciers. Continuity of the Loess from Switzerland to the Low Countries. Characteristic Organic Remains not Lacustrine. Alpine Gravel in the Valley of the Rhine covered by Loess. Geographical Distribution of the Loess and its Height above the Sea. Fossil Mammalia. Loess of the Danube. Oscillations in the Level of the Alps and lower Country required to explain the Formation and Denudation of the Loess. More rapid Movement of the Inland Country. The same Depression and Upheaval might account for the Advance and Retreat of the Alpine Glaciers. Himalayan Mud of the Plains of the Ganges compared to European Loess. Human Remains in Loess near Maestricht, and their probable Antiquity. NATURE AND ORIGIN OF THE LOESS. Intimately connected with the subjects treated of in the last chapter, is the nature, origin, and age of certain loamy deposits, commonly called loess, which form a marked feature in the superficial deposits of the basins of the Rhine, Danube, and some other large rivers draining the Alps, and which extend down the Rhine into the Low Countries, and were once perhaps continuous with others of like composition in the north of France. [35] It has been reported of late years that human remains have been detected at several points in the loess of the Meuse around and below Maestricht. I have visited the localities referred to; but, before giving an account of them, it will be desirable to explain what is meant by the loess, a step the more necessary as a French geologist for whose knowledge and judgment I have great respect, tells me he has come to the conclusion that "the loess" is "a myth," having no real existence in a geological sense or as holding a definite place in the chronological series. No doubt it is true that in every country, and at all geological periods, rivers have been depositing fine loam on their inundated plains in the manner explained above in Chapter 3, where the Nile mud was spoken of. This mud of the plains of Egypt, according to Professor Bischoff's chemical analysis agrees closely in composition with the loess of the Rhine.* (* "Chemical and Physical Geology" volume 1 page 132.) I have also shown when speaking of the fossil man of Natchez, how identical in mineral character and in the genera of its terrestrial and amphibious shells is the ancient fluviatile loam of the Mississippi with the loess of the Rhine. But granting that loam presenting the same aspect has originated at different times and in distinct hydrographical basins, it is nevertheless true that during the glacial period the Alps were a great centre of dispersion, not only of erratics, as we have seen in the last chapter, and of gravel which was carried farther than the erratics, but also of very fine mud which was transported to still greater distances and in greater volume down the principal river-courses between the mountains and the sea. MUD PRODUCED BY GLACIERS. They who have visited Switzerland are aware that every torrent which issues from an icy cavern at the extremity of a glacier is densely charged with an impalpable powder, produced by the grinding action to which the subjacent floor of rock and the stones and sand frozen into the ice are exposed in the manner before described. We may therefore readily conceive that a much greater volume of fine sediment was swept along by rivers swollen by melting ice at the time of the retreat of the gigantic glaciers of the olden time. The fact that a large proportion of this mud, instead of being carried to the ocean where it might have formed a delta on the coast or have been dispersed far and wide by the tides and currents, has accumulated in inland valleys, will be found to be an additional proof of the former occurrence of those grand oscillations in the level of the Alps and parts of the adjoining continent which were required to explain the alternate advance and retreat of the glaciers, and the superposition of more than one boulder clay and stratified alluvium. The position of the loess between Basle and Bonn is such as to imply that the great valley of the Rhine had already acquired its present shape, and in some places, perhaps more than its actual depth and width, previously to the time when it was gradually filled up to a great extent with fine loam. The greater part of this loam has been since removed, so that a fringe only of the deposit is now left on the flanks of the boundary hills, or occasionally some outliers in the middle of the great plain of the Rhine where it expands in width. These outliers are sometimes on such a scale as to admit of minor hills and valleys, having been shaped out of them by the action of rain and small streamlets, as near Freiburg in the Breisgau and other districts. FOSSIL SHELLS OF THE LOESS. [Illustration: Figures 44, 45, and 46] (FIGURE 44. Succinea oblonga.) (FIGURE 45. Pupa muscorum.) (FIGURE 46. Helix hispida, Lin.; H. plebeia, Drap.) The loess is generally devoid of fossils, although in many places they are abundant, consisting of land-shells, all of living species, and comprising no small part of the entire molluscous fauna now inhabiting the same region. The three shells most frequently met with are those represented in the annexed figures (44, 45 and 46). The slug, called Succinea, is not strictly aquatic, but lives in damp places, and may be seen in full activity far from rivers, in meadows where the grass is wet with rain or dew; but shells of the genera Limnaea, Planorbis, Paludina, Cyclas, and others, requiring to be constantly in the water, are extremely exceptional in the loess, occurring only at the bottom of the deposit where it begins to alternate with ancient river-gravel on which it usually reposes. This underlying gravel consists in the valley of the Rhine for the most part of pebbles and boulders of Alpine origin, showing that there was a time when the rivers had power to convey coarse materials for hundreds of miles northwards from Switzerland towards the sea; whereas at a later period an entire change was brought about in the physical geography of the same district, so that the same river deposited nothing but fine mud, which accumulated to a thickness of 800 feet or more above the original alluvial plain. But although most of the fundamental gravel was derived from the Alps, there has been observed in the neighbourhood of the principal mountain chains bordering the great valley, such as the Black Forest, Vosges, and Odenwald, an admixture of detritus characteristic of those several chains. We cannot doubt therefore that as some of these mountains, especially the Vosges, had during the glacial period their own glaciers, a part of the fine mud of their moraines must have been mingled with loess of Alpine origin; although the principal mass of the latter must have come from Switzerland, and can in fact be traced continuously from Basle to Belgium. GEOGRAPHICAL DISTRIBUTION OF THE LOESS. It was stated in the last chapter that at the time of the greatest extension of the Swiss glaciers the Lake of Constance and all the other great lakes were filled with ice, so that gravel and mud could pass freely from the upper Alpine valley of the Rhine to the lower region between Basle and the sea, the great lake intercepting no part of the moraines whether fine or coarse. On the other hand the Aar with its great tributaries the Limmat and the Reuss does not join the Rhine till after it issues from the Lake of Constance; and by their channels a large part of the Alpine gravel and mud could always have passed without obstruction into the lower country, even after the ice of the great lake had melted. It will give the reader some idea of the manner in which the Rhenish loess occurs, if he is told that some of the earlier scientific observers imagined it to have been formed in a vast lake which occupied the valley of the Rhine from Basle to Mayence, sending up arms or branches into what are now the valleys of the Main, Neckar, and other large rivers. They placed the barrier of this imaginary lake in the narrow and picturesque gorge of the Rhine between Bingen and Coblenz: and when it was objected that the lateral valley of the Lahn, communicating with that gorge, had also been filled with loess, they were compelled to transfer the great dam farther down and to place it below Bonn. Strictly speaking it must be placed much farther north, or in the 51st parallel of latitude, where the limits of the loess have been traced out by MM. Omalius D'Halloy, Dumont, and others, running east and west by Cologne, Juliers, Louvain, Oudenarde, and Courtrai in Belgium to Cassel, near Dunkirk in France. This boundary line may not indicate the original seaward extent of the formation, as it may have stretched still farther north and its present abrupt termination may only show how far it was cut back at some former period by the denuding action of the sea. Even if the imbedded fossil shells of the loess had been lacustrine, instead of being, as we have seen, terrestrial and amphibious, the vast height and width of the required barrier would have been fatal to the theory of a lake: for the loess is met with in great force at an elevation of no less than 1600 feet above the sea, covering the Kaiserstuhl, a volcanic mountain which stands in the middle of the great valley of the Rhine, near Freiburg in Breisgau. The extent to which the valley has there been the receptacle of fine mud afterwards removed is most remarkable. The loess of Belgium was called "Hesbayan mud" in the geological map of the late M. Dumont, who, I am told, recognised it as being in great part composed of Alpine mud. M. d'Archiac, when speaking of the loess, observes that it envelopes Hainault, Brabant, and Limburg like a mantle everywhere uniform and homogeneous in character, filling up the lower depressions of the Ardennes and passing thence into the north of France, though not crossing into England. In France, he adds, it is found on high plateaus 600 feet above some of the rivers, such as the Marne; but as we go southwards and eastwards of the basin of the Seine, it diminishes in quantity, and finally thins out in those directions.* (* D'Archiac, "Histoire des Progres" volume 2 pages 169, 170.) It may even be a question whether the "limon des plateaux," or upland loam of the Somme valley, before alluded to,* may not be a part of the same formation. (* Number 4 Figure 7.) As to the higher and lower level gravels of that valley, which, like that of the Seine, contain no foreign rocks, we have seen that they are each of them covered by deposits of loess or inundation-mud belonging respectively to the periods of the gravels, whereas the upland loam is of much older date, more widely spread, and occupying positions often independent of the present lines of drainage. To restore in imagination the geographical outline of Picardy, to which rivers charged with so much homogeneous loam and running at such heights may once have belonged is now impossible.* (* See above, Chapter 8. ) In the valley of the Rhine, as I before observed, the body of the loess, instead of having been formed at successively lower and lower levels as in the case of the basin of the Somme, was deposited in a wide and deep pre-existing basin, or strath, bounded by lofty mountain chains such as the Black Forest, Vosges, and Odenwald. In some places the loam accumulated to such a depth as first to fill the valley and then to spread over the adjoining table-lands, as in the case of the Lower Eifel, where it encircled some of the modern volcanic cones of loose pumice and ashes. In these instances it does not appear to me that the volcanoes were in eruption during the time of the deposition of the loess, as some geologists have supposed. The interstratification of loam and volcanic ejectamenta was probably occasioned by the fluviatile mud having gradually enveloped the cones of loose scoriae after they were completely formed. I am the more inclined to embrace this view after having seen the junction of granite and loess on the steep slopes of some of the mountains bounding the great plain of the Rhine on its right bank in the Bergstrasse. Thus between Darmstadt and Heidelberg perpendicular sections are seen of loess 200 feet thick, at various heights above the river, some of them at elevations of 800 feet and upwards. In one of these may be seen, resting on the hill side of Melibocus in the Odenwald, the usual yellow loam free from pebbles at its contact with a steep slope of granite, but divided into horizontal layers for a short distance from the line of junction. In these layers, which abut against the granite, a mixture of mica and of unrounded grains of quartz and felspar occur, evidently derived from the disintegration of the crystalline rock, which must have decomposed in the atmosphere before the mud had reached this height. Entire shells of Helix, Pupa, and Succinea, of the usual living species, are embedded in the granitic mixture. We may therefore be sure that the valley bounded by steep hills of granite existed before the tranquil accumulation of this vast body of loess. During the re-excavation of the basin of the Rhine successive deposits of loess of newer origin were formed at various heights; and it is often difficult to distinguish their relative ages, especially as fossils are often entirely wanting, and the mineral composition of the formation is so uniform. The loess in Belgium is variable in thickness, usually ranging from 10 to 30 feet. It caps some of the highest hills or table-land around Brussels at the height of 300 feet above the sea. In such places it usually rests on gravel and rarely contains shells, but when they occur they are of Recent species. I found the Succinea oblonga, before mentioned, and Helix hispida in the Belgian loess at Neerepen, between Tongres and Hasselt, where M. Bosquet had previously obtained remains of an elephant referred to E. primigenius. This pachyderm and Rhinoceros tichorhinus are cited as characterising the loess in various parts of the valley of the Rhine. Several perfect skeletons of the marmot have been disinterred from the loess of Aix-la-Chapelle. But much remains to be done in determining the species of mammalia of this formation and the relative altitudes above the valley-plain at which they occur. If we ascend the basin of the Neckar, we find that it is filled with loess of great thickness, far above its junction with the Rhine. At Canstadt near Stuttgart, loess resembling that of the Rhine contains many fossil bones, especially those of Elephas primigenius, together with some of Rhinoceros tichorhinus, the species having been lately determined by Dr. Falconer. At this place the loess is covered by a thick bed of travertine, used as a building stone, the product of a mineral spring. In the travertine are many fossil plants, all Recent except two, an oak and poplar, the leaves of which Professor Heer has not been able to identify with any known species. Below the loess of Canstadt, in which bones of the mammoth are so abundant, is a bed of gravel evidently an old river channel now many feet above the level of the Neckar, the valley having there been excavated to some depth below its ancient channel so as to lie in the underlying red sandstone of Keuper. Although the loess, when traced from the valley of the Rhine into that of the Neckar, or into any other of its tributaries, often undergoes some slight alteration in its character, yet there is so much identity of composition as to suggest the idea that the mud of the main river passed far up the tributary valleys, just as that of the Mississippi during floods flows far up the Ohio, carrying its mud with it into the basin of that river. But the uniformity of colour and mineral composition does not extend indefinitely into the higher parts of every basin. In that of the Neckar, for example, near Tubingen, I found the fluviatile loam or brick-earth, enclosing the usual Helices and Succineae, together with the bones of the mammoth, very distinct in colour and composition from ordinary Rhenish loess, and such as no one could confound with Alpine mud. It is mottled with red and green, like the New Red Sandstone or Keuper, from which it has clearly been derived. Such examples, however, merely show that where a basin is so limited in size that the detritus is derived chiefly or exclusively from one formation, the prevailing rock will impart its colour and composition in a very decided manner to the loam; whereas, in the basin of a great river which has many tributaries, the loam will consist of a mixture of almost every variety of rock, and will therefore exhibit an average result nearly the same in all countries. Thus, the loam which fills to a great depth the wide valley of the Saone, which is bounded on the west side by an escarpment of Inferior Oolite, and by the chain of the Jura on the east, is very like the loess found in the continuation of the same great basin after the junction of the Rhone, by which a large supply of Alpine mud has been added and intermixed. In the higher parts of the basin of the Danube, loess of the same character as that of the Rhine, and which I believe to be chiefly of Alpine origin, attains a far greater elevation above the sea than any deposits of Rhenish loess; but the loam which, according to M. Stur, fills valleys on the north slope of the Carpathians almost up to the watershed between Galicia and Hungary, may be derived from a distinct source. OSCILLATIONS OF LEVEL REQUIRED TO EXPLAIN THE ACCUMULATION AND DENUDATION OF THE LOESS. A theory, therefore, which attempts to account for the position of the loess cannot be satisfactory unless it be equally applicable to the basins of the Rhine and Danube. So far as relates to the source of so much homogeneous loam, there are many large tributaries of the Danube which, during the glacial period, may have carried an ample supply of moraine-mud from the Alps to that river; and in regard to grand oscillations in the level of the land, it is obvious that the same movements both downward and upward of the great mountain-chain would be attended with analogous effects, whether the great rivers flowed northwards or eastwards. In each case fine loam would be accumulated during subsidence and removed during the upheaval of the land. Changes, therefore, of level analogous to those on which we have been led to speculate when endeavouring to solve the various problems presented by the glacial phenomena, are equally available to account for the nature and geological distribution of the loess. But we must suppose that the amount of depression and re-elevation in the central region was considerably in excess of that experienced in the lower countries, or those nearer the sea, and that the rate of subsidence in the latter was never so considerable as to cause submergence, or the admission of the sea into the interior of the continent by the valleys of the principal rivers. We have already assumed that the Alps were loftier than now, when they were the source of those gigantic glaciers which reached the flanks of the Jura. At that time gravel was borne to the greatest distances from the central mountains through the main valleys, which had a somewhat steeper slope than now, and the quantity of river-ice must at that time have aided in the transportation of pebbles and boulders. To this state of things gradually succeeded another of an opposite character, when the fall of the rivers from the mountains to the sea became less and less, while the Alps were slowly sinking, and the first retreat of the great glaciers was taking place. Suppose the depression to have been at the rate of 5 feet in a century in the mountains and only as many inches in the same time nearer the coast, still, in such areas as the eye could survey at once, comprising a small part only of Switzerland or of the basin of the Rhine, the movement might appear to be uniform and the pre-existing valleys and heights might seem to remain relatively to each other as before. Such inequality in the rate of rising or sinking, when we contemplate large continental spaces, is quite consistent with what we know of the course of nature in our own times as well as at remote geological epochs. Thus in Sweden, as before stated, the rise of land now in progress is nearly uniform as we proceed from north to south for moderate distances; but it greatly diminishes southwards if we compare areas hundreds of miles apart; so that instead of the land rising about 5 feet in a hundred years as at the North Cape, it becomes less than the same number of inches at Stockholm, and farther south the land is stationary, or, if not, seems rather to be descending than ascending.* (* "Principles of Geology" chapter 30 9th edition page 519 et seq.) To cite an example of high geological antiquity, M. Hebert has demonstrated that, during the Oolitic and Cretaceous periods, similar inequalities in the vertical movements of the earth's crust took place in Switzerland and France. By his own observations and those of M. Lory he has proved that the area of the Alps was rising and emerging from beneath the ocean towards the close of the Oolitic epoch, and was above water at the commencement of the Cretaceous era; while, on the other hand, the area of the Jura, about 100 miles to the north, was slowly sinking at the close of the Oolitic period, and had become submerged at the commencement of the Cretaceous. Yet these oscillations of level were accomplished without any perceptible derangement in the strata, which remained all the while horizontal, so that the Lower Cretaceous or Neocomian beds were deposited conformably on the Oolitic.* (* "Bulletin de la Societe Geologique de France" 2 series volume 16 1859 page 596.) Taking for granted then that the depression was more rapid in the more elevated region, the great rivers would lose century after century some portion of their velocity or carrying power, and would leave behind them on their alluvial plains more and more of the moraine-mud with which they were charged, till at length, in the course of thousands or some tens of thousands of years, a large part of the main valleys would begin to resemble the plains of Egypt where nothing but mud is deposited during the flood season. The thickness of loam containing shells of land and amphibious mollusca might in this way accumulate to any extent, so that the waters might overflow some of the heights originally bounding the valley and deposits of "platform mud," as it has been termed in France, might be extensively formed. At length, whenever a re-elevation of the Alps at the time of the second extension of the glaciers took place, there would be renewed denudation and removal of such loess; and if, as some geologists believe, there has been more than one oscillation of level in the Alps since the commencement of the glacial period, the changes would be proportionally more complicated and terraces of gravel covered with loess might be formed at different heights and at different periods. HIMALAYAN MUD OF THE GANGES COMPARED TO EUROPEAN LOESS. Some of the revolutions in physical geography above suggested for the continent of Europe during the Pleistocene epoch, may have had their counterparts in India in the Recent Period. The vast plains of Bengal are overspread with Himalayan mud, which as we ascend the Ganges extends inland for 1200 miles from the sea, continuing very homogeneous on the whole, though becoming more sandy as it nears the hills. They who sail down the river during a season of inundation see nothing but a sheet of water in every direction, except here and there where the tops of trees emerge above its level. To what depth the mud extends is not known, but it resembles the loess in being generally devoid of stratification, and of shells, though containing occasionally land shells in abundance, as well as calcareous concretions, called kunkur, which may be compared to the nodules of carbonate of lime sometimes observed to form layers in the Rhenish loess. I am told by Colonel Strachey and Dr. Hooker that above Calcutta, in the Hooghly, when the flood subsides, the Gangetic mud may be seen in river cliffs 80 feet high, in which they were unable to detect organic remains, a remark which I found to hold equally in regard to the Recent mud of the Mississippi. Dr. Wallich, while confirming these observations, informs me that at certain points in Bengal, farther inland, he met with land-shells in the banks of the great river. Borings have been made at Calcutta, beginning not many feet above the sea-level, to the depth of 300 and 400 feet; and wherever organic remains were found in the strata pierced through they were of a fluviatile or terrestrial character, implying that during a long and gradual subsidence of the country the sediment thrown down by the Ganges and Brahmaputra had accumulated at a sufficient rate to prevent the sea from invading that region. At the bottom of the borings, after passing through much fine loam, beds of pebbles, sand, and boulders were reached, such as might belong to an ancient river channel; and the bones of a crocodile and the shell of a freshwater tortoise were met with at the depth of 400 feet from the surface. No pebbles are now brought down within a great distance of this point, so that the country must once have had a totally different character and may have had its valleys, hills, and rivers, before all was reduced to one common level by the accumulation upon it of fine Himalayan mud. If the latter were removed during a gradual re-elevation of the country, many old hydrographical basins might reappear, and portions of the loam might alone remain in terraces on the flanks of hills, or on platforms, attesting the vast extent in ancient times of the muddy envelope. A similar succession of events has, in all likelihood, occurred in Europe during the deposition and denudation of the loess of the Pleistocene period, which, as we have seen in a former chapter, was long enough to allow of the gradual development of almost any amount of such physical changes. HUMAN REMAINS IN THE LOESS NEAR STRASBURG. M. Ami Boue, well known by his numerous works on geology and a well-practised observer in every branch of the science, disinterred in the year 1823 with his own hands many bones of a human skeleton from ancient undisturbed loess at Lahr, nearly opposite Strasburg, on the right side of the great valley of the Rhine. No skull was detected, but the tibia, fibula, and several other bones were obtained in a good state of preservation and shown at the time to Cuvier, who pronounced them to be human. HUMAN REMAINS IN LOESS NEAR MAESTRICHT. The banks of the Meuse at Maestricht, like those of the Rhine at Bonn and Cologne, are slightly elevated above the level of the alluvial plain. On the right bank of the Meuse, opposite Maestricht, the difference of level is so marked that a bridge with many arches has been constructed to keep up, during the flood season, a communication between the higher parts of the alluvial plain and the hills or bluffs which bound it. This plain is composed of modern loess, undistinguishable in mineral character from that of higher antiquity, before alluded to, and entirely without signs of successive deposition and devoid of terrestrial or fluviatile shells. It is extensively worked for brick-earth to the depth of about 8 feet. The bluffs before alluded to often consist of a terrace of gravel, from 30 to 40 feet in thickness, covered by an older loess, which is continuous as we ascend the valley to Liege. In the suburbs of that city patches of loess are seen at the height of 200 feet above the level of the Meuse. The table-land in that region, composed of Carboniferous and Devonian rocks, is about 450 feet high, and is not overspread with loess. A terrace of gravel covered with loess has been mentioned as existing on the right bank of the Meuse at Maestricht. Answering to it another is also seen on the left bank below that city, and a promontory of it projecting into the alluvial plain of the Meuse and approaching to within a hundred yards of the river, was cut through during the excavation of a canal running from Maestricht to Hocht, between the years 1815 and 1823. This section occurs at the village of Smeermass, and is about 60 feet deep, the lower 40 feet consisting of stratified gravel and the upper of 20 feet of loess. The number of molars, tusks, and bones (probably parts of entire skeletons) of elephants obtained during these diggings, was extraordinary. Not a few of them are still preserved in the museums of Maestricht and Leyden, together with some horns of deer, bones of the ox-tribe and other mammalia, and a human lower jaw, with teeth. According to Professor Crahay, who published an account of it at the time, this jaw, which is now preserved at Leyden, was found at the depth of 19 feet from the surface, where the loess joins the underlying gravel, in a stratum of sandy loam resting on gravel and overlaid by some pebbly and sandy beds. The stratum is said to have been intact and undisturbed, but the human jaw was isolated, the nearest tusk of an elephant being six yards removed from it in horizontal distance. Most of the other mammalian bones were found; like these human remains, in or near the gravel, but some of the tusks and teeth of elephants were met with much nearer the surface. I visited the site of these fossils in 1860 in company with M. van Binkhorst, and we found the description of the ground, published by the late Professor Crahay of Louvain, to be very correct.* (* M. van Binkhorst has shown me the original manuscript read to the Maestricht Athenaeum in 1823. The memoir was published in 1836 in the "Bulletin de l'Academie Royale de Belgique" volume 3 page 43.) The projecting portion of the terrace, which was cut through in making the canal, is called the hill of Caberg, which is flat-topped, 60 feet high, and has a steep slope on both sides towards the alluvial plain. M. van Binkhorst (who is the author of some valuable works on the palaeontology of the Maestricht Chalk) has recently visited Leyden, and ascertained that the human fossil above mentioned is still entire in the museum of the University. Although we had no opportunity of verifying the authenticity of Professor Crahay's statements, we could see no reason for suspecting the human jaw to belong to a different geological period from that of the extinct elephant. If this were granted, it might have no claims to a higher antiquity than the human remains which Dr. Schmerling disentombed from the Belgian caverns; but the fact of their occurring in a Pleistocene alluvial deposit in the open plains, would be one of the first examples of such a phenomenon. The top of the hill of Caberg is not so high above the Meuse as is the terrace of St. Acheul with its flint implements above the Somme, but at St. Acheul no human bones have yet been detected. In the museum at Maestricht are preserved a human frontal and a pelvic bone, stained of a dark peaty colour; the frontal very remarkable for its lowness and the prominence of the superciliary ridges, which resemble those of the Borreby skull, Figure 5. These remains may be the same as those alluded to by Professor Crahay in his memoir, where he says that in a black deposit in the suburbs of Hocht were found leaves, nuts, and freshwater shells in a very perfect state, and a human skull of a dark colour. They were of an age long posterior to that of the loess containing the bones of elephants and in which the human jaw now at Leyden is said to have been embedded. CHAPTER 17. -- POST-GLACIAL DISLOCATIONS AND FOLDINGS OF CRETACEOUS AND DRIFT STRATA IN THE ISLAND OF MOEN, IN DENMARK. Geological Structure of the Island of Moen. Great Disturbances of the Chalk posterior in Date to the Glacial Drift, with Recent Shells. M. Puggaard's Sections of the Cliffs of Moen. Flexures and Faults common to the Chalk and Glacial Drift. Different Direction of the Lines of successive Movement, Fracture, and Flexure. Undisturbed Condition of the Rocks in the adjoining Danish Islands. Unequal Movements of Upheaval in Finmark. Earthquake of New Zealand in 1855. Predominance in all Ages of uniform Continental Movements over those by which the Rocks are locally convulsed. In the preceding chapters I have endeavoured to show that the study of the successive phases of the glacial period in Europe, and the enduring marks which they have left on many of the solid rocks and on the character of the superficial drift are of great assistance in enabling us to appreciate the vast lapse of ages which are comprised in the Pleistocene epoch. They enlarge at the same time our conception of the antiquity, not only of the living species of animals and plants but of their present geographical distribution, and throw light on the chronological relations of these species to the earliest date yet ascertained for the existence of the human race. That date, it will be seen, is very remote if compared to the times of history and tradition, yet very modern if contrasted with the length of time during which all the living testacea, and even many of the mammalia, have inhabited the globe. In order to render my account of the phenomena of the glacial epoch more complete, I shall describe in this chapter some other changes in physical geography and in the internal structure of the earth's crust, which have happened in the Pleistocene period, because they differ in kind from any previously alluded to, and are of a class which were thought by the earlier geologists to belong exclusively to epochs anterior to the origin of the existing fauna and flora. Of this nature are those faults and violent local dislocations of the rocks, and those sharp bendings and foldings of the strata, which we so often behold in mountain chains, and sometimes in low countries also, especially where the rock-formations are of ancient date. POST-GLACIAL DISLOCATIONS AND FOLDINGS OF CRETACEOUS AND DRIFT STRATA IN THE ISLAND OF MOEN, DENMARK. A striking illustration of such convulsions of Pleistocene date may be seen in the Danish island of Moen, which is situated about 50 miles south of Copenhagen. The island is about 60 miles in circumference, and consists of white Chalk, several hundred feet thick, overlaid by boulder clay and sand, or glacial drift which is made up of several subdivisions, some unstratified and others stratified, the whole having a mean thickness of 60 feet, but sometimes attaining nearly twice that thickness. In one of the oldest members of the formation fossil marine shells of existing species have been found. Throughout the greater part of Moen the strata of the drift are undisturbed and horizontal, as are those of the subjacent Chalk; but on the north-eastern coast they have been throughout a certain area bent, folded, and shifted, together with the beds of the underlying Cretaceous formation. Within this area they have been even more deranged than is the English Chalk-with-flints along the central axis of the Isle of Wight in Hampshire, or of Purbeck in Dorsetshire. The whole displacement of the Chalk is evidently posterior in date to the origin of the drift, since the beds of the latter are horizontal where the fundamental Chalk is horizontal, and inclined, curved, or vertical where the Chalk displays signs of similar derangement. Although I had come to these conclusions respecting the structure of Moen in 1835, after devoting several days in company with Dr. Forchhammer to its examination,* (* Lyell, "Geological Transactions" 2nd series volume 2 page 243.) I should have hesitated to cite the spot as exemplifying convulsions on so grand a scale, of such extremely modern date, had not the island been since thoroughly investigated by a most able and reliable authority, the Danish geologist, Professor Puggaard, who has published a series of detailed sections of the cliffs. These cliffs extend through the north-eastern coast of the island, called Moens Klint,* where the Chalk precipices are bold and picturesque, being 300 and 400 feet high, with tall beech-trees growing on their summits, and covered here and there at their base with huge taluses of fallen drift, verdant with wild shrubs and grass, by which the monotony of a continuous range of white Chalk cliffs is prevented. (* Puggaard, "Geologie d. Insel Moen" Bern 1851; and "Bulletin de la Societe Geologique de France" 1851.) [Illustration: Figure 47 and 48. Southern Extremity Of Moens Klint] (FIGURE 47. SOUTHERN EXTREMITY OF MOENS KLINT (PUGGAARD). A. Horizontal drift. B. Chalk and overlying drift beginning to rise. C. First flexure and fault. Height of cliff at this point, 180 feet.) (FIGURE 48. SECTION OF MOENS KLINT (PUGGAARD), CONTINUED FROM FIGURE 47. S. Fossil shells of recent species in the drift at this point. G. Greatest height near G, 280 feet.) In the low part of the island, at A, Figure 47, or the southern extremity of the line of section above alluded to, the drift is horizontal, but when we reach B, a change, both in the height of the cliffs and in the inclination of the strata, begins to be perceptible, and the Chalk Number 1 soon makes its appearance from beneath the overlying members of the drift Numbers 2, 3, 4, and 5. This Chalk, with its layers of flints, is so like that of England as to require no description. The incumbent drift consists of the following subdivisions, beginning with the lowest: Number 2. Stratified loam and sand, 5 feet thick, containing at one spot near the base of the cliff, at s, Figure 48, Cardium edule, Tellina solidula, and Turritella, with fragments of other shells. Between Number 2 and the Chalk Number 1, there usually intervenes a breccia of broken flints. Number 3. Unstratified blue clay or till, with small pebbles and fragments of Scandinavian rocks occasionally scattered through it, 20 feet thick. Number 4. A second unstratified mass of yellow and more sandy clay 40 feet thick, with pebbles and angular polished and striated blocks of granite and other Scandinavian rocks, transported from a distance. Number 5. Stratified sands and gravel, with occasionally large erratic blocks; the whole mass varying from 40 to 100 feet in thickness, but this only in a few spots. The angularity of many of the blocks in Numbers 3 and 4, the glaciated surfaces of others, and the transportation from a distance attested by their crystalline nature, prove them to belong to the northern drift or glacial period. It will be seen that the four subdivisions 2, 3, 4, and 5 begin to rise at B, Figure 47, and that at C, where the cliff is 180 feet high, there is a sharp flexure shared equally by the Chalk and the incumbent drift. Between D and G, Figure 48, we observe a great fracture in the rocks with synclinal and anticlinal folds, exhibited in cliffs nearly 300 feet high, the drift beds participating in all the bendings of the Chalk; that is to say, the three lower members of the drift, including Number 2, which, at the point S in this diagram, contains the shells of Recent species before alluded to. Near the northern end of the Moens Klint, at a place called "Taler," more than 300 feet high, are seen similar folds, so sharp that there is an appearance of four distinct alternations of the glacial and Cretaceous formations in vertical or highly inclined beds; the Chalk at one point bending over so that the position of all the beds is reversed. [Illustration: Figure 49. Post-Glacial Disturbances] (FIGURE 49. POST-GLACIAL DISTURBANCES OF VERTICAL, FOLDED, AND SHIFTED STRATA OF CHALK AND DRIFT, IN THE DRONNINGESTOL, MOEN, HEIGHT 400 FEET (PUGGAARD). 1. Chalk with flints. 2. Marine stratified loam, lowest member of glacial formation. 3. Blue clay or till, with erratic blocks unstratified. 4. Yellow sandy till, with pebbles and glaciated boulders. 5. Stratified sand and gravel with erratics.) But the most wonderful shiftings and faultings of the beds are observable in the Dronningestol part of the same cliff, 400 feet in perpendicular height, where, as shown in Figure 49, the drift is thoroughly entangled and mixed up with the dislocated Chalk. If we follow the lines of fault, we may see, says M. Puggaard, along the planes of contact of the shifted beds, the marks of polishing and rubbing which the Chalk flints have undergone, as have many stones in the gravel of the drift, and some of these have also been forced into the soft Chalk. The manner in which the top of some of the arches of bent Chalk have been cut off in this and several adjoining sections, attests the great denudation which accompanied the disturbances, portions of the bent strata having been removed, probably while they were emerging from beneath the sea. M. Puggaard has deduced the following conclusions from his study of these cliffs. First. The white Chalk, when it was still in horizontal stratification, but after it had suffered considerable denudation, subsided gradually, so that the lower beds of drift Number 2, with their littoral shells, were superimposed on the Chalk in a shallow sea. Second. The overlying unstratified boulder clays 3 and 4 were thrown down in deeper water by the aid of floating ice coming from the north. Third. Irregular subsidences then began, and occasionally partial failures of support, causing the bending and sometimes the engulfment of overlying masses both of the Chalk and drift, and causing the various dislocations above described and depicted. The downward movement continued till it exceeded 400 feet, for upon the surface even of Number 5, in some parts of the island, lie huge erratics 20 feet or more in diameter, which imply that they were carried by ice in a sea of sufficient depth to float large icebergs. But these big erratics, says Puggaard, never enter into the fissures as they would have done had they been of date anterior to the convulsions. Fourth. After this subsidence, the re-elevation and partial denudation of the Cretaceous and glacial beds took place during a general upward movement, like that now experienced in parts of Sweden and Norway. In regard to the lines of movement in Moen, M. Puggaard believes, after an elaborate comparison of the cliffs with the interior of the island, that they took at least three distinct directions at as many successive eras, all of post-glacial date; the first line running from east-south-east to west-north-west, with lines of fracture at right angles to them; the second running from south-south-east to north-north-west, also with fractures in a transverse direction; and lastly, a sinking in a north and south direction, with other subsidences of contemporaneous date running at right angles or east and west. When we approach the north-west end of Moens Klint, or the range of coast above described, the strata begin to be less bent and broken, and after travelling for a short distance beyond we find the Chalk and overlying drift in the same horizontal position as at the southern end of the Moens Klint. What makes these convulsions the more striking is the fact that in the other adjoining Danish islands, as well as in a large part of Moen itself, both the Secondary and Tertiary formations are quite undisturbed. It is impossible to behold such effects of reiterated local movements, all of post-Tertiary date, without reflecting that, but for the accidental presence of the stratified drift, all of which might easily have been missing, where there has been so much denudation, even if it had once existed, we might have referred the verticality and flexures and faults of the rocks to an ancient period, such as the era between the Chalk with flints and the Maestricht Chalk, or to the time of the latter formation, or to the Eocene, or Miocene, or Pliocene eras, even the last of them long prior to the commencement of the glacial epoch. Hence we may be permitted to suspect that in some other regions, where we have no such means at our command for testing the exact date of certain movements, the time of their occurrence may be far more modern than we usually suppose. In this way some apparent anomalies in the position of erratic blocks, seen occasionally at great heights above the parent rocks from which they have been detached, might be explained, as well as the irregular direction of certain glacial furrows like those described by Professor Keilhau and Mr. Horbye on the mountains of the Dovrefjeld in latitude 62 degrees north, where the striation and friction is said to be independent of the present shape and slope of the mountains.* (* "Observations sur les Phenomenes d'Erosion en Norwege" 1857.) Although even in such cases it remains to be proved whether a general crust of continental ice, like that of Greenland described by Rink (see above, Chapter 13), would not account for the deviation of the furrows and striae from the normal directions which they ought to have followed had they been due to separate glaciers filling the existing valleys. It appears that in general the upward movements in Scandinavia, which have raised sea-beaches containing marine shells of Recent species to the height of several hundred feet, have been tolerably uniform over very wide spaces; yet a remarkable exception to this rule was observed by M. Bravais at Altenfjord in Finmark, between latitude 70 and 71 degrees north. An ancient water-level, indicated by a sandy deposit forming a terrace and by marks of the erosion of the waves, can be followed for 30 miles from south to north along the borders of a fjord rising gradually from a height of 85 feet to an elevation of 220 feet above the sea, or at the rate of about 4 feet in a mile.* (* "Proceedings of the Geological Society" 1845 volume 4 page 94.) To pass to another and very remote part of the world, we have witnessed so late as January 1855 in the northern island of New Zealand a sudden and permanent rise of land on the northern shores of Cook's Straits, which at one point, called Muko-muka, was so unequal as to amount to 9 feet vertically, while it declined gradually from this maximum of upheaval in a distance of about 23 miles north-west of the greatest rise, to a point where no change of level was perceptible. Mr. Edward Roberts of the Royal Engineers, employed by the British Government at the time of the shock in executing public works on the coast, ascertained that the extreme upheaval of certain ancient rocks followed a line of fault running at least 90 miles from south to north into the interior; and what is of great geological interest, immediately to the east of this fault the country, consisting of Tertiary strata, remained unmoved or stationary; a fact well established by the position of a line of Nullipores marking the sea-level before the earthquake, both on the surface of the Tertiary and Palaeozoic rocks.* (* "Bulletin de la Societe Geologique de France" volume 13 1856 page 660, where I have described the facts communicated to me by Messrs. Roberts and Walter Mantell.) The repetition of such unequal movements, especially if they recurred at intervals along the same lines of fracture, would in the course of ages cause the strata to dip at a high angle in one direction, while towards the opposite point of the compass they would terminate abruptly in a steep escarpment. But it is probable that the multiplication of such movements in the post-Tertiary period has rarely been so great as to produce results like those above described in Moen, for the principal movements in any given period seem to be of a more uniform kind, by which the topography of limited districts and the position of the strata are not visibly altered except in their height relatively to the sea. Were it otherwise we should not find conformable strata of all ages, including the primary fossiliferous of shallow-water origin, which must have remained horizontal throughout vast areas during downward movements of several thousand feet going on at the period of their accumulation. Still less should we find the same primary strata, such as the Carboniferous, Devonian, or Silurian, still remaining horizontal over thousands of square leagues, as in parts of North America and Russia, having escaped dislocation and flexure throughout the entire series of epochs which separate Palaeozoic from Recent times. Not that they have been motionless, for they have undergone so much denudation, and of such a kind, as can only be explained by supposing the strata to have been subjected to great oscillations of level, and exposed in some cases repeatedly to the destroying and planing action of the waves of the sea. It seems probable that the successive convulsions in Moen were contemporary with those upward and downward movements of the glacial period which were described in the thirteenth and some of the following chapters, and that they ended before the upper beds of Number 5, Figure 49, with its large erratic blocks, were deposited, as some of those beds occurring in the disturbed parts of Moen appear to have escaped the convulsions to which Numbers 2, 3, and 4 were subjected. If this be so, the whole derangement, although Pleistocene, may have been anterior to the human epoch, or rather to the earliest date to which the existence of man has as yet been traced back. CHAPTER 18. -- THE GLACIAL PERIOD IN NORTH AMERICA. Post-glacial Strata containing Remains of Mastodon giganteus in North America. Scarcity of Marine Shells in Glacial Drift of Canada and the United States. Greater southern Extension of Ice-action in North America than in Europe. Trains of Erratic Blocks of vast Size in Berkshire, Massachusetts. Description of their Linear Arrangement and Points of Departure. Their Transportation referred to Floating and Coast Ice. General Remarks on the Causes of former Changes of Climate at successive geological Epochs. Supposed Effects of the Diversion of the Gulf Stream in a Northerly instead of North-Easterly Direction. Development of extreme Cold on the opposite Sides of the Atlantic in the Glacial period not strictly simultaneous. Effect of Marine Currents on Climate. Pleistocene Submergence of the Sahara. On the North American continent, between the arctic circle and the 42nd parallel of latitude, we meet with signs of ice-action on a scale as grand as, if not grander than, in Europe; and there also the excess of cold appears to have been first felt at the close of the Tertiary, and to have continued throughout a large portion of the Pleistocene period. [36] The general absence of organic remains in the North American glacial formation makes it as difficult as in Europe to determine what mammalia lived on the continent at the time of the most intense refrigeration, or when extensive areas were becoming strewed over with glacial drift and erratic blocks, but it is certain that a large proboscidean now extinct, the Mastodon giganteus, Cuv., together with many other quadrupeds, some of them now living and others extinct, played a conspicuous part in the post-glacial era. By its frequency as a fossil species, this pachyderm represents the European Elephas primigenius, although the latter also occurs fossil in the United States and Canada, and abounds, as I learn from Sir John Richardson, in latitudes farther north than those to which the mastodon has been traced. In the state of New York, the mastodon is not unfrequently met with in bogs and lacustrine deposits formed in hollows in the drift, and therefore, in a geological position, much resembling that of Recent peat and shell-marl in the British Isles, Denmark, or the valley of the Somme, as before described. Sometimes entire skeletons have been discovered within a few feet of the surface, in peaty earth at the bottom of small ponds, which the agriculturists had drained. The shells in these cases belong to freshwater genera, such as Limnaea, Physa, Planorbis, Cyclas, and others, differing from European species, but the same as those now proper to ponds and lakes in the same parts of America. I have elsewhere given an account of several of these localities which I visited in 1842,* and can state that they certainly have a more modern aspect than almost all the European deposits in which remains of the mammoth occur, although a few instances are cited of Elephas Primigenius having been dug out of peat in Great Britain. (* "Travels in North America" volume 1 page 55 London 1845; and "Manual of Geology" chapter 12 5th edition page 144.) Thus I was shown a mammoth's tooth in the museum at Torquay in Devonshire which is believed to have been dredged up from a deposit of vegetable matter now partially submerged beneath the sea. A more elevated part of the same peaty formation constitutes the bottom of the valley in which Tor Abbey stands. This individual elephant must certainly have been of more modern date than his fellows found fossil in the gravel of the Brixham cave, before described, for it flourished when the physical geography of Devonshire, unlike that of the cave period, was almost identical with that now established. I cannot help suspecting that many tusks and teeth of the mammoth, said to have been found in peat, may be as spurious as are the horns of the rhinoceros cited more than once in the "Memoirs of the Wernerian Society" as having been obtained from shell-marl in Forfarshire and other Scotch counties; yet, between the period when the mammoth was most abundant and that when it died out, there must have elapsed a long interval of ages when it was growing more and more scarce; and we may expect to find occasional stragglers buried in deposits long subsequent in date to others, until at last we may succeed in tracing a passage from the Pleistocene to the Recent fauna, by geological monuments, which will fill up the gap before alluded to as separating the era of the flint tools of Amiens and Abbeville from that of the peat of the valley of the Somme. How far the lacustrine strata of North America above mentioned may help to lessen this hiatus, and whether some individuals of the Mastodon giganteus may have come down to the confines of the historical period, is a question not so easily answered as might at first sight be supposed. A geologist might naturally imagine that the fluviatile formation of Goat Island, seen at the falls of Niagara, and at several points below the falls,* was very modern, seeing that the fossil shells contained in it are all of species now inhabiting the waters of the Niagara, and seeing also that the deposit is more modern than the glacial drift of the same locality. (* "Travels in North America" by the author, volume 1 chapter 2 and volume 2 chapter 19.) In fact, the old river bed, in which bones of the mastodon occur, holds the same position relatively to the boulder formation as the strata of shell-marl and bog-earth with bones of mastodon, so frequent in the State of New York, bear to the glacial drift, and all may be of contemporaneous date. But in the case of the valley of the Niagara we happen to have a measure of time which is wanting in the other localities, namely, the test afforded by the recession of the falls, an operation still in progress, by which the deep ravine of the Niagara, 7 miles long, between Queenstown and Goat Island has been hollowed out. This ravine is not only post-glacial, but also posterior in date to the fluviatile or mastodon-bearing beds. The individual therefore found fossil near Goat Island flourished before the gradual excavation of the deep and long chasm, and we must reckon its antiquity, not by thousands, but by tens of thousands of years, if I have correctly estimated the minimum of time which was required for the erosion of that great ravine.* (* "Principles of Geology" 9th edition page 2; and "Travels in North America" volume 1 page 32 1845.) The stories widely circulated of bones of the mastodon having been observed with their surfaces pierced as if by arrow-heads or bearing the marks of wounds inflicted by some stone implement, must in future be more carefully inquired into, for we can scarcely doubt that the mastodon in North America lived down to a period when the mammoth co-existed with Man in Europe. But I need say no more on this subject, having already explained my views in regard to the evidence of the antiquity of Man in North America when treating of the human bone discovered at Natchez on the Mississippi. In Canada and the United States we experience the same difficulty as in Europe when we attempt to distinguish between glacial formations of submarine and those of supra-marine origin. In the New World, as in Scotland and England, marine shells of this era have rarely been traced higher than 500 feet above the sea, and 700 feet seems to be the maximum to which at present they are known to ascend. In the same countries, erratic blocks have travelled from north to south, following the same direction as the glacial furrows and striae imprinted almost everywhere on the solid rocks underlying the drift. Their direction rarely deviates more than fifteen degrees east or west of the meridian, so that we can scarcely doubt, in spite of the general dearth of marine shells, that icebergs floating in the sea and often running aground on its rocky bottom were the instruments by which most of the blocks were conveyed to southern latitudes. There are, nevertheless, in the United States, as in Europe, several groups of mountains which have acted as independent centres for the dispersion of erratics, as, for example, the White Mountains, latitude 44 degrees north, the highest of which, Mount Washington, rises to about 6300 feet above the sea; and according to Professor Hitchcock some of the loftiest of the hills of Massachusetts once sent down their glaciers into the surrounding lower country. GREAT SOUTHERN EXTENSION OF TRAINS OF ERRATIC BLOCKS IN BERKSHIRE, MASSACHUSETTS, U.S., LATITUDE 42 DEGREES NORTH. Having treated so fully in this volume of the events of the glacial period, I am unwilling to conclude without laying before the reader the evidence displayed in North America of ice-action in latitudes farther south by about ten degrees than any seen on an equal scale in Europe. This extension southwards of glacial phenomena in regions where there are no snow-covered mountains like the Alps to explain the exception, nor any hills of more than moderate elevation, constitutes a feature of the western as compared to the eastern side of the Atlantic, and must be taken into account when we speculate on the causes of the refrigeration of the northern hemisphere during the Pleistocene period. [Illustration: Figure 50. Erratic Blocks In Berkshire, Massachusetts] (FIGURE 50. MAP SHOWING THE RELATIVE POSITION AND DIRECTION OF SEVEN TRAINS OF ERRATIC BLOCKS IN BERKSHIRE, MASSACHUSETTS, AND IN PART OF THE STATE OF NEW YORK. Distance in a straight line, between the mountain ranges A and C, about eight miles. A. Canaan range, in the State of New York. The crest consists of green chloritic rock. B. Richmond range, the western division of which consists in Merriman's Mount of the same green rock as A, but in a more schistose form, while the eastern division is composed of slaty limestone. C. The Lenox range, consisting in part of mica-schist, and in some districts of crystalline limestone. d. Knob in the range A, from which most of the train Number 6 is supposed to have been derived. e. Supposed starting point of the train Number 5 in the range A. f. Hiatus of 175 yards, or space without blocks. g. Sherman's House. h. Perry's Peak. k. Flat Rock. l. Merriman's Mount. m. Dupey's Mount. n. Largest block of train, Number 6. See Figures 51 and 52. p. Point of divergence of part of the train Number 6, where a branch is sent off to Number 5. Number 1. The most southerly train examined by Messrs. Hall and Lyell, between Stockbridge and Richmond, composed of blocks of black slate, blue limestone and some of the green Canaan rock, with here and there a boulder of white quartz. Number 2. Train composed chiefly of large limestone masses, some of them divided into two or more fragments by natural joints. Number 3. Train composed of blocks of limestone and the green Canaan rock; passes south of the Richmond Station on the Albany and Boston railway; is less defined than Numbers 1 and 2. Number 4. Train chiefly of limestone blocks, some of them thirty feet in diameter, running to the north-west of the Richmond Station, and passing south of the Methodist Meeting-house, where it is intersected by a railway cutting. Number 5. South train of Dr. Reid, composed entirely of large blocks of the green chloritic Canaan rock; passes north of the Old Richmond Meeting-house, and is three-quarters of a mile north of the preceding train (Number 4). Number 6. The great or principal train (north train of Dr. Reid), composed of very large blocks of the Canaan rock, diverges at p, and unites by a branch with train Number 5. Number 7. A well-defined train of limestone blocks, with a few of the Canaan rock, traced from the Richmond to the slope of the Lenox range.) In 1852, accompanied by Mr. James Hall, state geologist of New York, author of many able and well-known works on geology and palaeontology, I examined the glacial drift and erratics of the county of Berkshire, Massachusetts, and those of the adjoining parts of the state of New York, a district about 130 miles inland from the Atlantic coast and situated due west of Boston in latitude 42 degrees 25 minutes north. This latitude corresponds in Europe to that of the north of Portugal. Here numerous detached fragments of rock are seen, having a linear arrangement or being continuous in long parallel trains, running nearly in straight lines over hill and dale for distances of 5, 10, and 20 miles, and sometimes greater distances. Seven of the more conspicuous of these trains, from 1 to 7 inclusive, Figure 50, are laid down in the accompanying map or ground plan.* (* This ground plan, and a farther account of the Berkshire erratics was given in an abstract of a lecture delivered by me to the Royal Institution of Great Britain, April 27, 1855 and published in their Proceedings.) It will be remarked that they run in a north-west and south-east direction, or almost transversely to the ranges of hills A, B, and C, which run north-north-east and south-south-west. The crests of these chains are about 800 feet in height above the intervening valleys. The blocks of the northernmost train, Number 7, are of limestone derived from the calcareous chain B; those of the two trains next to the south, Numbers 6 and 5, are composed exclusively in the first part of their course of a green chloritic rock of great toughness, but after they have passed the ridge B, a mixture of calcareous blocks is observed. After traversing the valley for a distance of 6 miles these two trains pass through depressions or gaps in the range C, as they had previously done in crossing the range B, showing that the dispersion of the erratics bears some relation to the acutal inequalities of the surface, although the course of the same blocks is perfectly independent of the more leading features of the geography of the country, or those by which the present lines of drainage are determined. The greater number of the green chloritic fragments in trains 5 and 6 have evidently come from the ridge A, and a large proportion of the whole from its highest summit d, where the crest of the ridge has been worn into those dome-shaped masses called "roches moutonnees," already alluded to, and where several fragments having this shape, some of them 30 feet long, are seen in situ, others only slightly removed from their original position, as if they had been just ready to set out on their travels. Although smooth and rounded on their tops they are angular on their lower parts, where their outline has been derived from the natural joints of the rock. Had these blocks been conveyed from d by glaciers, they would have radiated in all directions from a centre, whereas not one even of the smaller ones is found to the westward of A, though a very slight force would have made them roll down to the base of that ridge, which is very steep on its western declivity. It is clear, therefore, that the propelling power, whatever it may have been, acted exclusively in a south-easterly direction. Professor Hall and I observed one of the green blocks--24 feet long, poised upon another about 19 feet in length. The largest of all on the west flank of m, or Dupey's Mount, called the Alderman, is above 90 feet in diameter, and nearly 300 feet in circumference. We counted at some points between forty and fifty blocks visible at once, the smallest of them larger than a camel. [Illustration: Figure 51. Dome-Shaped Block] (FIGURE 51. ERRATIC DOME-SHAPED BLOCK OF COMPACT CHLORITIC ROCK (n in map in Figure 50), near the Richmond Meeting-house, Berkshire, Massachusetts, latitude 42 degrees 25 minutes North. Length, 52 feet; width, 40 feet; height above the soil, 15 feet.) The annexed drawing (Figure 51) represents one of the best known of train Number 6, being that marked n on the map (Figure 50). According to our measurement it is 52 feet long by 40 in width, its height above the drift in which it is partially buried being 15 feet. At the distance of several yards occurs a smaller block, 3 or 4 feet in height, 20 feet long, and 14 broad, composed of the same compact chloritic rock, and evidently a detached fragment from the bigger mass, to the lower and angular part of which it would fit on exactly. This erratic n has a regularly rounded top, worn and smoothed like the "roches moutonnees" before mentioned, but no part of the attrition can have occurred since it left its parent rock, the angles of the lower portion being quite sharp and unblunted. [Illustration: Figure 52. Position of Block in Figure 51] (FIGURE 52. SECTION SHOWING THE POSITION OF THE BLOCK IN FIGURE 51. a. The large block in Figure 51 and n in the map in Figure 50. b. Fragment detached from the same. c. Unstratified drift with boulders. d. Silurian limestone in inclined stratification.) From railway cuttings through the drift of the neighbourhood and other artificial excavations, we may infer that the position of the block n, if seen in a vertical section, would be as represented in Figure 52. The deposit c in that section consists of sand, mud, gravel, and stones, for the most part unstratified, resembling the till or boulder clay of Europe. It varies in thickness from 10 to 50 feet, being of greater depth in the valleys. The uppermost portion is occasionally, though rarely, stratified. Some few of the imbedded stones have flattened, polished, striated, and furrowed sides. They consist invariably, like the seven trains above mentioned, of kinds of rock confined to the region lying to the north-west, none of them having come from any other quarter. Whenever the surface of the underlying rock has been exposed by the removal of the superficial detritus, a polished and furrowed surface is seen, like that underneath a glacier, the direction of the furrows being from north-west to south-east, or corresponding to the course of the large erratics. As all the blocks, instead of being dispersed from a centre, have been carried in one direction and across the ridges A, B, C and the intervening valleys, the hypothesis of glaciers is out of the question. I conceive, therefore, that the erratics were conveyed to the places they now occupy by coast ice, when the country was submerged beneath the waters of a sea cooled by icebergs coming annually from arctic regions. [Illustration: Figure 53. Canaan And Richmond Valleys] (FIGURE 53. SECTION THROUGH CANAAN AND RICHMOND VALLEYS AT A TIME WHEN THEY WERE MARINE CHANNELS. d, e. Masses of floating ice carrying fragments of rock.) Suppose the highest peaks of the ridges A, B, C in the annexed diagram (Figure 53) to be alone above water, forming islands, and d e to be masses of floating ice, which drifted across the Canaan and Richmond valleys at a time when they were marine channels, separating islands or rather chains of islands, having a north-north-east and south-south-west direction. A fragment of ice such as d, freighted with a block from A, might run aground and add to the heap of erratics at the north-west base of the island (now ridge) B, or, passing through a sound between B and the next island of the same group, might float on till it reached the channel between B and C. Year after year two such exposed cliffs in the Canaan range as d and e of the map, Figure 50, undermined by the waves, might serve as the points of departure of blocks, composing the trains Numbers 5 and 6. It may be objected that oceanic currents could not always have had the same direction; this may be true, but during a short season of the year when the ice was breaking up the prevailing current may have always run south-east. If it be asked why the blocks of each train are not more scattered, especially when far from their source, it may be observed that after passing through sounds separating islands, they issued again from a new and narrow starting-point; moreover, we must not exaggerate the regularity of the trains, as their width is sometimes twice as great in one place in as another; and Number 6 sends off a branch at p, which joins Number 5. There are also stragglers, or large blocks here and there in the spaces between the two trains. As to the distance to which any given block would be carried, that must have depended on a variety of circumstances; such as the strength of the current, the direction of the wind, the weight of the block or the quantity and draught of the ice attached to it. The smaller fragments would, on the whole, have the best chance of going farthest; because, in the first place, they were more numerous, and then, being lighter, they required less ice to float them, and would not ground so readily on shoals, or if stranded, would be more easily started again on their travels. Many of the blocks, which at first sight seem to consist of single masses, are found when examined to be made up of two, three, or more pieces divided by natural joints. In the case of a second removal by ice, one or more portions would become detached and be drifted to different points further on. Whenever this happened, the original size would be lessened, and the angularity of the block previously worn by the breakers would be restored, and this tendency to split may explain why some of the far-transported fragments remain very angular. These various considerations may also account for the fact that the average size of the blocks of all the seven trains laid down on the plan, Figure 50, lessens sensibly in proportion as we recede from the principal points of departure of particular kinds of erratics, yet not with any regularity, a huge block now and then recurring when the rest of the train consists of smaller ones. All geologists acquainted with the district now under consideration are agreed that the mountain ranges A, B, and c, as well as the adjoining valleys, had assumed their actual form and position before the drift and erratics accumulated on and in them and before the surface of the fixed rocks was polished and furrowed. I have the less hesitation in ascribing the transporting power to coast-ice, because I saw in 1852 an angular block of sandstone, 8 feet in diameter, which had been brought down several miles by ice only three years before to the mouth of the Petitcodiac estuary, in Nova Scotia, where it joins the Bay of Fundy; and I ascertained that on the shores of the same bay, at the South Joggins, in the year 1850, much larger blocks had been removed by coast-ice, and after they had floated half a mile, had been dropped in salt water by the side of a pier built for loading vessels with coal, so that it was necessary at low tide to blast these huge ice-borne rocks with gunpowder in order that the vessels might be able to draw up alongside the pier. These recent exemplifications of the vast carrying powers of ice occurred in latitude 46 degrees north (corresponding to that of Bordeaux), in a bay never invaded by icebergs. I may here remark that a sheet of ice of moderate thickness, if it extend over a wide area, may suffice to buoy up the largest erratics which fall upon it. The size of these will depend, not on the intensity of the cold but on the manner in which the rock is jointed, and the consequent dimensions of the blocks into which it splits when falling from an undermined cliff. When I first endeavoured in the "Principles of Geology" in 1830,* to explain the causes, both of the warmer and colder climates which have at former periods prevailed on the globe, I referred to successive variations in the height and position of the land and its extent relatively to the sea in polar and equatorial latitudes--also to fluctuations in the course of oceanic currents and other geographical conditions, by the united influence of which I still believe the principal revolutions in the meteorological state of the atmosphere at different geological periods have been brought about. (* 1st edition chapter 7; 9th edition ibid.) The Gulf Stream was particularly alluded to by me as moderating the winter climate of northern Europe and as depending for its direction on temporary and accidental peculiarities in the shape of the land, especially that of the narrow Straits of Bahama, which a slight modification in the earth's crust would entirely alter. Mr. Hopkins, in a valuable essay on the causes of former changes of climate,*nhas attempted to calculate how much the annual temperature of Europe would be lowered if this Gulf Stream were turned in some other and new direction, and estimates the amount at about six or seven degrees of Fahrenheit. (* Hopkins, "Quarterly Journal of the Geological Society" volume 8 1852 page 56.) He also supposes that if at the same time a considerable part of northern and central Europe were submerged, so that a cold current from the arctic seas should sweep over it, an additional refrigeration of three or four degrees would be produced. He has speculated in the same essay on the effects which would be experienced in the eastern hemisphere if the same mighty current of warm water, instead of crossing the Atlantic, were made to run northwards from the Gulf of Mexico through the region now occupied by the valley of the Mississippi, and so onwards to the arctic regions. After reflecting on what has been said in the thirteenth chapter of the submergence and re-elevation of the British Isles and the adjoining parts of Europe, and the rising and sinking of the Alps and the basins of some of the great rivers flowing from that chain, since the commencement of the glacial period, a geologist will not be disposed to object to the theory above adverted to, on the score of its demanding too much conversion of land into sea, or almost any amount of geographical change in Pleistocene times. But a difficulty of another kind presents itself. We have seen that, during the glacial period, the cold in Europe extended much farther south than it does at present, and in this chapter we have demonstrated that in North America the cold also extended no less than 10 degrees of latitude still farther southwards than in Europe; so that if a great body of heated water, instead of flowing north-eastward, were made to pass through what is now the centre of the American continent towards the Arctic Circle, it could not fail to mitigate the severity of the winter's cold in precisely those latitudes where the cold was greatest and where it has left monuments of ice-action surpassing in extent any exhibited on the European side of the ocean. In the actual state of the globe, the isothermal lines, or lines of equal winter temperature when traced westward from Europe to North America bend 10 degrees south, there being a marked excess of winter cold in corresponding latitudes west of the Atlantic. During the glacial period, viewing it as a whole, we behold signs of a precisely similar deflection of these same isothermal lines when followed from east to west; so that if, in the hope of accounting for the former severity of glacial action in Europe, we suppose the absence of the Gulf Stream and imagine a current of equivalent magnitude to have flowed due north from the Gulf of Mexico, we introduce, as we have just hinted, a source of heat into precisely that part of the continent where the extreme conditions of refrigeration are most manifest. Viewed in this light, the hypothesis in question would render the glacial phenomena described in the present chapter more perplexing and anomalous than ever. But here another question arises, whether the eras at which the maximum of cold was attained on the opposite sides of the Atlantic were really contemporaneous? We have now discovered not only that the glacial period was of vast duration, but that it passed through various phases and oscillations of temperature; so that, although the chief polishing and furrowing of the rocks and transportation of erratics in Europe and North America may have taken place contemporaneously, according to the ordinary language of geology, or when the same testacea and the same Pleistocene assemblage of mammalia flourished, yet the extreme development of cold on the opposite sides of the ocean may not have been strictly simultaneous, but on the contrary the one may have preceded or followed the other by a thousand or more than a thousand centuries. It is probable that the greatest refrigeration of Norway, Sweden, Scotland, Wales, the Vosges, and the Alps coincided very nearly in time; but when the Scandinavian and Scotch mountains were encrusted with a general covering of ice, similar to that now enveloping Greenland, this last country may not have been in nearly so glacial a condition as now, just as we find that the old icy crust and great glaciers, which have left their mark on the mountains of Norway and Sweden, have now disappeared, precisely at a time when the accumulation of ice in Greenland is so excessive. In other words, we see that in the present state of the northern hemisphere, at the distance of about 1500 miles, two meridional zones enjoying very different conditions of temperature may co-exist, and we are, therefore, at liberty to imagine some former alternations of colder and milder climates on the opposite sides of the ocean throughout the Pleistocene era of a compensating kind, the cold on the one side balancing the milder temperature on the other. By assuming such a succession of events we can more easily explain why there has not been a greater extermination of species, both terrestrial and aquatic, in polar and temperate regions during the glacial epoch, and why so many species are common to pre-glacial and post-glacial times. The numerous plants which are common to the temperate zones north and south of the equator have been referred by Mr. Darwin and Dr. Hooker to migrations which took place along mountain chains running from north to south during some of the colder phases of the glacial epoch.* (* Darwin, "Origin of Species" chapter 11 page 365; Hooker, "Flora of Australia" Introduction page 18 1859.) Such an hypothesis enables us to dispense with the doctrine that the same species ever originated independently in two distinct and distant areas; and it becomes more feasible if we admit the doctrine of the co-existence of meridional belts of warmer and colder climate, instead of the simultaneous prevalence of extreme cold both in the eastern and western hemisphere. It also seems necessary, as colder currents of water always flow to lower latitudes, while warmer ones are running towards polar regions, that some such compensation should take place, and that an increase of cold in one region must to a certain extent be balanced by a mitigation of temperature elsewhere. Sir John F. Herschel, in his recent work on "Physical Geography," when speaking of the open sea which is caused in part of the polar regions by the escape of ice through Behring's Straits, and the flow of warmer water northwards through the same channel, observes that these straits, by which the continents of Asia and North America are now parted, "are only thirty miles broad where narrowest and only twenty-five fathoms in their greatest depth." But "this narrow channel," he adds, "is yet important in the economy of nature, inasmuch as it allows a portion of the circulating water from a warmer region to find its way into the polar basin, aiding thereby not only to mitigate the extreme rigour of the polar cold, but to prevent in all probability a continual accretion of ice, which else might rise to a mountainous height."* (* Herschel's "Physical Geography" page 41 1861.) Behring's Straits, here alluded to, happen to agree singularly in width and depth with the Straits of Dover, the difference in depth not being more than 3 or 4 feet; so that at the rate of upheaval, which is now going on in many parts of Scandinavia, of 2 1/2 feet in a century, such straits might be closed in 3000 years, and a vast accumulation of ice to the northward commence forthwith. But, on the other hand, although such an accumulation might spread its refrigerating influence for many miles southwards beyond the new barrier, the warm current which now penetrates through the straits, and which at other times is chilled by floating ice issuing from them, would when totally excluded from all communication with the icy sea have its temperature raised and its course altered, so that the climate of some other area must immediately begin to improve. There is still another probable cause of a vast change in the temperature of central Europe in comparatively modern times, to which no allusion has yet been made; namely, the conversion of the great desert of the Sahara from sea into land since the commencement of the Pleistocene period. When that vast region was still submerged, no sirocco blowing for days in succession carried its hot blasts from a wide expanse of burning sand across the Mediterranean. The south winds were comparatively cool, allowing the snows of the Alps to augment to an extent which the colossal dimensions of the moraines of extinct glaciers can alone enable us to estimate. The scope and limits of this volume forbid my pursuing these speculations and reasonings farther; but I trust I have said enough to show that the monuments of the glacial period, when more thoroughly investigated, will do much towards expanding our views as to the antiquity of the fauna and flora now contemporary with Man, and will therefore enable us the better to determine the time at which Man began in the northern hemisphere to form part of the existing fauna. [37] CHAPTER 19. -- RECAPITULATION OF GEOLOGICAL PROOFS OF MAN'S ANTIQUITY. Recapitulation of Results arrived at in the earlier Chapters. Ages of Stone and Bronze. Danish Peat and Kitchen-Middens. Swiss Lake-Dwellings. Local Changes in Vegetation and in the wild and domesticated Animals and in Physical Geography coeval with the Age of Bronze and the later Stone Period. Estimates of the positive Date of some Deposits of the later Stone Period. Ancient Division of the Age of Stone of St. Acheul and Aurignac. Migrations of Man in that Period from the Continent to England in Post-Glacial Times. Slow Rate of Progress in barbarous Ages. Doctrine of the superior Intelligence and Endowments of the original Stock of Mankind considered. Opinions of the Greeks and Romans, and their Coincidence with those of the Modern Progressionist. The ages of stone and bronze, so called by archaeologists, were spoken of in the earlier chapters of this work. That of bronze has been traced back to times anterior to the Roman occupation of Helvetia, Gaul, and other countries north of the Alps. When weapons of that mixed metal were in use, a somewhat uniform civilisation seems to have prevailed over a wide extent of central and northern Europe, and the long duration of such a state of things in Denmark and Switzerland is shown by the gradual improvement which took place in the useful and ornamental arts. Such progress is attested by the increasing variety of the forms, and the more perfect finish and tasteful decoration of the tools and utensils obtained from the more modern deposits of the bronze age, those from the upper layers of peat, for example, as compared to those found in the lower ones. The great number also of the Swiss lake-dwellings of the bronze age (about seventy villages having been already discovered), and the large population which some of them were capable of containing, afford indication of a considerable lapse of time, as does the thickness of the stratum of mud in which in some of the lakes the works of art are entombed. The unequal antiquity, also, of the settlements is occasionally attested by the different degrees of decay which the wooden stakes or piles have undergone, some of them projecting more above the mud than others, while all the piles of the antecedent age of stone have rotted away quite down to the level of the mud, such part of them only as was originally driven into the bed of the lake having escaped decomposition.* (* Troyon, "Habitations lacustres" Lausanne 1860.) Among the monuments of the stone period, which immediately preceded that of bronze, the polished hatchets called celts are abundant, and were in very general use in Europe before metallic tools were introduced. We learn, from the Danish peat and shell-mounds, and from the older Swiss lake-settlements, that the first inhabitants were hunters who fed almost entirely on game, but their food in after ages consisted more and more of tamed animals and still later a more complete change to a pastoral state took place, accompanied as population increased by the cultivation of some cereals. Both the shells and quadrupeds belonging to the later stone period and to the age of bronze consist exclusively of species now living in Europe, the fauna being the same as that which flourished in Gaul at the time when it was conquered by Julius Caesar, even the Bos primigenius, the only animal of which the wild type is lost, being still represented, according to Cuvier, Bell, and Rutimeyer, by one of the domesticated races of cattle now in Europe. These monuments, therefore, whether of stone or bronze, belong to what I have termed geologically the Recent period, the definition of which some may think rather too dependent on negative evidence, or on the non-discovery hitherto of extinct mammalia, such as the mammoth, which may one day turn up in a fossil state in some of the oldest peaty deposits, as indeed it is already said to have done at some spots, though I have failed as yet to obtain authentic evidence of the fact.* (* A molar of E. primigenius, in a very fresh state, in the museum at Torquay, believed to have been washed up by the waves of the sea out of the submerged mass of vegetable matter at the extremity of the valley in which Tor Abbey stands, is the best case I have seen. See above, Chapter 18.) No doubt some such exceptional cases may be met with in the course of future investigations, for we are still imperfectly acquainted with the entire fauna of the age of stone in Denmark as we may infer from an opinion expressed by Steenstrup, that some of the instruments exhumed by antiquaries from the Danish peat are made of the bones and horns of the elk and reindeer. Yet no skeleton or uncut bone of either of those species has hitherto been observed in the same peat. Nevertheless, the examination made by naturalists of the various Danish and Swiss deposits of the Recent period has been so searching, that the finding in them of a stray elephant or rhinoceros, should it ever occur, would prove little more than that some few individuals lingered on, when the species was on the verge of extinction, and such rare exceptions would not render the classification above proposed inappropriate. At the time when many wild quadrupeds and birds were growing scarce and some of them becoming locally extirpated in Denmark, great changes were taking place in the vegetation. The pine, or Scotch fir, buried in the oldest peat, gave place at length to the oak, and the oak, after flourishing for ages, yielded in its turn to the beech, the periods when these three forest trees predominated in succession tallying pretty nearly with the ages of stone, bronze, and iron in Denmark. In the same country also, during the stone period, various fluctuations, as we have seen, occurred in physical geography. Thus, on the ocean side of certain islands, the old refuse-heaps, or "kitchen-middens," were destroyed by the waves, the cliffs having wasted away, while on the side of the Baltic, where the sea was making no encroachment or where the land was sometimes gaining on the sea, such mounds remained uninjured. It was also shown that the oyster, which supplied food to the primitive people, attained its full size in parts of the Baltic where it cannot now exist owing to a want of saltness in the water, and that certain marine univalves and bivalves, such as the common periwinkle, mussel, and cockle, of which the castaway shells are found in the mounds, attained in the olden time their full dimensions, like the oysters, whereas the same species, though they still live on the coast of the inland sea adjoining the mounds, are dwarfed and never half their natural size, the water being rendered too fresh for them by the influx of so many rivers. Some archaeologists and geologists of merit have endeavoured to arrive at positive dates, or an exact estimate of the minimum of time assignable to the later age of stone. These computations have been sometimes founded on changes in the level of the land, or on the increase of peat, as in the Danish bogs, or on the conversion of water into land by alluvial deposits, since certain lake-settlements in Switzerland were abandoned. Alterations also in the geographical distribution or preponderance of certain living species of animals and plants have been taken into account in corroboration, as have the signs of progress in human civilisation, as serving to mark the lapse of time during the stone and bronze epochs. M. Morlot has estimated with care the probable antiquity of three superimposed vegetable soils cut open at different depths in the delta of the Tiniere, each containing human bones or works of art, belonging successively to the Roman, bronze, and later stone periods. According to his estimate, an antiquity of 7000 years at least must be assigned to the oldest of these remains, though believed to be long posterior in date to the time when the mammoth and other extinct mammalia flourished together with Man in Europe. Such computations of past time must be regarded as tentative in the present state of our knowledge and much collateral evidence will be required to confirm them; yet the results appear to me already to afford a rough approximation to the truth. Between the newer or Recent division of the stone period and the older division, which has been called the Pleistocene, there was evidently a vast interval of time--a gap in the history of the past, into which many monuments of intermediate date will one day have to be intercalated. Of this kind are those caves in the south of France, in which M. Lartet has lately found bones of the reindeer, associated with works of art somewhat more advanced in style than those of St. Acheul or of Aurignac. In the valley of the Somme we have seen that peat exists of great thickness, containing in its upper layers Roman and Celtic memorials, the whole of which has been of slow growth, in basins or depressions conforming to the present contour and drainage levels of the country, and long posterior in date to older gravels, containing bones of the mammoth and a large number of flint implements of a very rude and antique type. Some of those gravels were accumulated in the channels of rivers which flowed at higher levels by 100 feet than the present streams, and before the valley had attained its present depth and form. No intermixture has been observed in those ancient river beds of any of the polished weapons, called "celts," or other relics of the more modern times, or of the second or Recent stone period, nor any interstratified peat; and the climate of those Pleistocene ages, when Man was a denizen of the north-west of France and of southern and central England, appears to have been much more severe in winter than it is now in the same region, though far less cold than in the glacial period which immediately preceded. We may presume that the time demanded for the gradual dying out or extirpation of a large number of wild beasts which figure in the Pleistocene strata and are missing in the Recent fauna was of protracted duration, for we know how tedious a task it is in our own times, even with the aid of fire-arms, to exterminate a noxious quadruped, a wolf, for example, in any region comprising within it an extensive forest or a mountain chain. In many villages in the north of Bengal, the tiger still occasionally carries off its human victims, and the abandonment of late years by the natives of a part of the Sunderbunds or lower delta of the Ganges, which they once peopled, is attributed chiefly to the ravages of the tiger. It is probable that causes more general and powerful than the agency of Man, alterations in climate, variations in the range of many species of animals, vertebrate and invertebrate, and of plants, geographical changes in the height, depth, and extent of land and sea, some or all of these combined, have given rise in a vast series of years to the annihilation, not only of many large mammalia, but to the disappearance of the Cyrena fluminalis, once common in the rivers of Europe, and to the different range or relative abundance of other shells which we find in the European drifts. That the growing power of Man may have lent its aid as the destroying cause of many Pleistocene species, must, however, be granted; yet, before the introduction of fire-arms, or even the use of improved weapons of stone, it seems more wonderful that the aborigines were able to hold their own against the cave-lion, hyaena, and wild bull, and to cope with such enemies, than that they failed to bring about their speedy extinction. It is already clear that Man was contemporary in Europe with two species of elephant, now extinct, E. primigenius and E. antiquus, two also of rhinoceros, R. tichorhinus and R. hemitoechus (Falc.), at least one species of hippopotamus, the cave-bear, cave-lion, and cave-hyaena, various bovine, equine, and cervine animals now extinct, and many smaller Carnivora, Rodentia, and Insectivora. While these were slowly passing away, the musk ox, reindeer, and other arctic species which have survived to our times were retreating northwards from the valleys of the Thames and Seine to their present more arctic haunts. The human skeletons of the Belgian caverns of times coeval with the mammoth and other extinct mammalia do not betray any signs of a marked departure in their structure, whether of skull or limb, from the modern standard of certain living races of the human family. As to the remarkable Neanderthal skeleton (Chapter 5), it is at present too isolated and exceptional, and its age too uncertain, to warrant us in relying on its abnormal and ape-like characters, as bearing on the question whether the farther back we trace Man into the past, the more we shall find him approach in bodily conformation to those species of the anthropoid quadrumana which are most akin to him in structure. In the descriptions already given of the geographical changes which the British Isles have undergone since the commencement of the glacial period (as illustrated by several maps, Figures 39 to 41), it has been shown that there must have been a free communication by land between the Continent and these islands, and between the several islands themselves, within the Pleistocene epoch, in order to account for the Germanic fauna and flora having migrated into every part of the area, as well as for the Scandinavian plants and animals to have retreated into the higher mountains. During some part of the Pleistocene ages, the large pachyderms and accompanying beasts of prey, now extinct, wandered from the Continent to England; and it is highly probable that France was united with some part of the British Isles as late as the period of the gravels of St. Acheul and the era of those engulfed rivers which, in the basin of the Meuse near Liege, swept into many a rent and cavern the bones of Man and of the mammoth and cave-bear. There have been vast geographical revolutions in the times alluded to, and oscillations of land, during which the English Channel, which can be shown by the Pagham erratics and the old Brighton beach (Chapter 14), to be of very ancient origin, may have been more than once laid dry and again submerged. During some one of these phases, Man may have crossed over, whether by land or in canoes, or even on the ice of a frozen sea (as Mr. Prestwich has hinted), for the winters of the period of the higher-level gravels of the valley of the Somme were intensely cold. The primitive people, who co-existed with the elephant and rhinoceros in the valley of the Ouse at Bedford, and who made use of flint tools of the Amiens type, certainly inhabited part of England which had already emerged from the waters of the glacial sea and the fabricators of the flint tools of Hoxne, in Suffolk, were also, as we have seen, post-glacial. We may likewise presume that the people of Pleistocene date, who have left their memorials in the valley of the Thames, were of corresponding antiquity, posterior to the boulder clay but anterior to the time when the rivers of that region had settled into their present channels. The vast distance of time which separated the origin of the higher and lower gravels of the valley of the Somme, both of them rich in flint implements of similar shape (although those of oval form predominate in the newer gravels), leads to the conclusion that the state of the arts in those early times remained stationary for almost indefinite periods. There may, however, have been different degrees of civilisation and in the art of fabricating flint tools, of which we cannot easily detect the signs in the first age of stone, and some contemporary tribes may have been considerably in advance of others. Those hunters, for example, who feasted on the rhinoceros and buried their dead with funeral rites at Aurignac may have been less barbarous than the savages of St. Acheul, as some of their weapons and utensils have been thought to imply. To a European who looks down from a great eminence on the products of the humble arts of the aborigines of all times and countries, the stone knives and arrows of the Red Indian of North America, the hatchets of the native Australian, the tools found in the ancient Swiss lake-dwellings or those of the Danish kitchen-middens and of St. Acheul, seem nearly all alike in rudeness and very uniform in general character. The slowness of the progress of the arts of savage life is manifested by the fact that the earlier instruments of bronze were modelled on the exact plan of the stone tools of the preceding age, although such shapes would never have been chosen had metals been known from the first. The reluctance or incapacity of savage tribes to adopt new inventions has been shown in the East by their continuing to this day to use the same stone implements as their ancestors, after that mighty empires, where the use of metals in the arts was well known, had flourished for three thousand years in their neighbourhood. We see in our own times that the rate of progress in the arts and sciences proceeds in a geometrical ratio as knowledge increases, and so when we carry back our retrospect into the past, we must be prepared to find the signs of retardation augmenting in a like geometrical ratio; so that the progress of a thousand years at a remote period may correspond to that of a century in modern times, and in ages still more remote Man would more and more resemble the brutes in that attribute which causes one generation exactly to imitate in all its ways the generation which preceded it. The extent to which even a considerably advanced state of civilisation may become fixed and stereotyped for ages, is the wonder of Europeans who travel in the East. One of my friends declared to me, that whenever the natives expressed to him a wish "that he might live a thousand years," the idea struck him as by no means extravagant, seeing that if he were doomed to sojourn for ever among them, he could only hope to exchange in ten centuries as many ideas, and to witness as much progress as he could do at home in half a century. It has sometimes happened that one nation has been conquered by another less civilised though more warlike, or that during social and political revolutions, people have retrograded in knowledge. In such cases, the traditions of earlier ages, or of some higher and more educated caste which has been destroyed, may give rise to the notion of degeneracy from a primaeval state of superior intelligence, or of science supernaturally communicated. But had the original stock of mankind been really endowed with such superior intellectual powers and with inspired knowledge and had possessed the same improvable nature as their posterity, the point of advancement which they would have reached ere this would have been immeasurably higher. We cannot ascertain at present the limits, whether of the beginning or the end, of the first stone period when Man co-existed with the extinct mammalia, but that it was of great duration we cannot doubt. During those ages there would have been time for progress of which we can scarcely form a conception, and very different would have been the character of the works of art which we should now be endeavouring to interpret--those relics which we are now disinterring from the old gravel-pits of St. Acheul, or from the Liege caves. In them, or in the upraised bed of the Mediterranean, on the south coast of Sardinia, instead of the rudest pottery or flint tools so irregular in form as to cause the unpractised eye to doubt whether they afford unmistakable evidence of design, we should now be finding sculptured forms surpassing in beauty the masterpieces of Phidias or Praxiteles; lines of buried railways or electric telegraphs from which the best engineers of our day might gain invaluable hints; astronomical instruments and microscopes of more advanced construction than any known in Europe, and other indications of perfection in the arts and sciences such as the nineteenth century has not yet witnessed. Still farther would the triumphs of inventive genius be found to have been carried, when the later deposits, now assigned to the ages of bronze and iron, were formed. Vainly should we be straining our imaginations to guess the possible uses and meaning of such relics--machines, perhaps, for navigating the air or exploring the depths of the ocean, or for calculating arithmetical problems beyond the wants or even the conception of living mathematicians. The opinion entertained generally by the classical writers of Greece and Rome, that Man in the first stage of his existence was but just removed from the brutes, is faithfully expressed by Horace in his celebrated lines, which begin:-- Quum prorepserunt primis animalia terris.--Sat. lib. 1, 3, 99. The picture of transmutation given in these verses, however severe and contemptuous the strictures lavishly bestowed on it by Christian commentators, accords singularly with the train of thought which the modern doctrine of progressive development has encouraged. "When animals," he says, "first crept forth from the newly formed earth, a dumb and filthy herd, they fought for acorns and lurking-places with their nails and fists, then with clubs, and at last with arms, which, taught by experience, they had forged. They then invented names for things and words to express their thoughts, after which they began to desist from war, to fortify cities and enact laws." They who in later times have embraced a similar theory, have been led to it by no deference to the opinions of their pagan predecessors, but rather in spite of very strong prepossessions in favour of an opposite hypothesis, namely, that of the superiority of their original progenitors, of whom they believe themselves to be the corrupt and degenerate descendants. So far as they are guided by palaeontology, they arrive at this result by an independent course of reasoning; but they have been conducted partly to the same goal as the ancients by ethnological considerations common to both, or by reflecting in what darkness the infancy of every nation is enveloped and that true history and chronology are the creation, as it were, of yesterday. CHAPTER 20. -- THEORIES OF PROGRESSION AND TRANSMUTATION. Antiquity and Persistence in Character of the existing Races of Mankind. Theory of their Unity of Origin considered. Bearing of the Diversity of Races on the Doctrine of Transmutation. Difficulty of defining the Terms "Species" and "Race." Lamarck's Introduction of the Element of Time into the Definition of a Species. His Theory of Variation and Progression. Objections to his Theory, how far answered. Arguments of modern Writers in favour of Progression in the Animal and Vegetable World. The old Landmarks supposed to indicate the first Appearance of Man, and of different Classes of Animals, found to be erroneous. Yet the Theory of an advancing Series of Organic Beings not inconsistent with Facts. Earliest known Fossil Mammalia of low Grade. No Vertebrata as yet discovered in the oldest Fossiliferous Rocks. Objections to the Theory of Progression considered. Causes of the Popularity of the Doctrine of Progression as compared to that of Transmutation. When speaking in a former work of the distinct races of mankind,* I remarked that, "if all the leading varieties of the human family sprang originally from a single pair" (a doctrine, to which then, as now, I could see no valid objection), "a much greater lapse of time was required for the slow and gradual formation of such races as the Caucasian, Mongolian, and Negro, than was embraced in any of the popular systems of chronology." (* "Principles of Geology" 7th edition page 637, 1847; see also 9th edition page 660.) In confirmation of the high antiquity of two of these, I referred to pictures on the walls of ancient temples in Egypt, in which, a thousand years or more before the Christian era, "the Negro and Caucasian physiognomies were portrayed as faithfully, and in as strong contrast, as if the likenesses of these races had been taken yesterday." In relation to the same subject, I dwelt on the slight modification which the Negro has undergone, after having been transported from the tropics and settled for more than two centuries in the temperate climate of Virginia. I therefore concluded that, "if the various races were all descended from a single pair, we must allow for a vast series of antecedent ages, in the course of which the long-continued influence of external circumstances gave rise to peculiarities increased in many successive generations and at length fixed by hereditary transmission." So long as physiologists continued to believe that Man had not existed on the earth above six thousand years, they might with good reason withhold their assent from the doctrine of a unity of origin of so many distinct races but the difficulty becomes less and less, exactly in proportion as we enlarge our ideas of the lapse of time during which different communities may have spread slowly, and become isolated, each exposed for ages to a peculiar set of conditions, whether of temperature, or food, or danger, or ways of living. The law of the geometrical rate of the increase of population which causes it always to press hard on the means of subsistence, would ensure the migration in various directions of offshoots from the society first formed abandoning the area where they had multiplied. But when they had gradually penetrated to remote regions by land or water--drifted sometimes by storms and currents in canoes to an unknown shore--barriers of mountains, deserts, or seas, which oppose no obstacle to mutual intercourse between civilised nations, would ensure the complete isolation for tens or thousands of centuries of tribes in a primitive state of barbarism. Some modern ethnologists, in accordance with the philosophers of antiquity, have assumed that men at first fed on the fruits of the earth, before even a stone implement or the simplest form of canoe had been invented. They may, it is said, have begun their career in some fertile island in the tropics, where the warmth of the air was such that no clothing was needed and where there were no wild beasts to endanger their safety. But as soon as their numbers increased they would be forced to migrate into regions less secure and blest with a less genial climate. Contests would soon arise for the possession of the most fertile lands, where game or pasture abounded and their energies and inventive powers would be called forth, so that at length they would make progress in the arts. But as ethnologists have failed, as yet, to trace back the history of any one race to the area where it originated, some zoologists of eminence have declared their belief that the different races, whether they be three, five, twenty, or a much greater number (for on this point there is an endless diversity of opinion),* have all been primordial creations, having from the first been stamped with the characteristic features, mental and bodily, by which they are now distinguished, except where intermarriage has given rise to mixed or hybrid races. (* See "Transactions of the Ethnological Society" volume 1 1861.) Were we to admit, say they, a unity of origin of such strongly marked varieties as the Negro and European, differing as they do in colour and bodily constitution, each fitted for distinct climates and exhibiting some marked peculiarities in their osteological, and even in some details of cranial and cerebral conformation, as well as in their average intellectual endowments--if, in spite of the fact that all these attributes have been faithfully handed down unaltered for hundreds of generations, we are to believe that, in the course of time, they have all diverged from one common stock, how shall we resist the arguments of the transmutationist, who contends that all closely allied species of animals and plants have in like manner sprung from a common parentage, albeit that for the last three or four thousand years they may have been persistent in character? Where are we to stop, unless we make our stand at once on the independent creation of those distinct human races, the history of which is better known to us than that of any of the inferior animals? So long as Geology had not lifted up a part of the veil which formerly concealed from the naturalist the history of the changes which the animate creation had undergone in times immediately antecedent to the Recent period, it was easy to treat these questions as too transcendental, or as lying too far beyond the domain of positive science to require serious discussion. But it is no longer possible to restrain curiosity from attempting to pry into the relations which connect the present state of the animal and vegetable worlds, as well as of the various races of mankind, with the state of the fauna and flora which immediately preceded. In the very outset of the inquiry, we are met with the difficulty of defining what we mean by the terms "species" and "race;" and the surprise of the unlearned is usually great, when they discover how wide is the difference of opinion now prevailing as to the significance of words in such familiar use. But, in truth, we can come to no agreement as to such definitions, unless we have previously made up our minds on some of the most momentous of all the enigmas with which the human intellect ever attempted to grapple. It is now thirty years since I gave an analysis in the first edition of my "Principles of Geology" (volume 2 1832) of the views which had been put forth by Lamarck, in the beginning of the century, on this subject. In that interval the progress made in zoology and botany, both in augmenting the number of known animals and plants, and in studying their physiology and geographical distribution and above all in examining and describing fossil species, is so vast that the additions made to our knowledge probably exceed all that was previously known; and what Lamarck then foretold has come to pass; the more new forms have been multiplied, the less are we able to decide what we mean by a variety, and what by a species. In fact, zoologists and botanists are not only more at a loss than ever how to define a species, but even to determine whether it has any real existence in nature, or is a mere abstraction of the human intellect, some contending that it is constant within certain narrow and impassable limits of variability, others that it is capable of indefinite and endless modification. Before I attempt to explain a great step, which has recently been made by Mr. Darwin and his fellow-labourers in this field of inquiry, I think it useful to recapitulate in this place some of the leading features of Lamarck's system, without attempting to adjust the claims of some of his contemporaries (Geoffroy St. Hilaire in particular) to share in the credit of some of his original speculations. From the time of Linnaeus to the commencement of the present century, it seemed a sufficient definition of the term species to say that "a species consisted of individuals all resembling each other, and reproducing their like by generation." But Lamarck after having first studied botany with success, had then turned his attention to conchology, and soon became aware that in the newer (or Tertiary) strata of the earth's crust there were a multitude of fossil species of shells, some of them identical with living ones, others simply varieties of the living, and which as such were entitled to be designated, according to the ordinary rules of classification, by the same names. He also observed that other shells were so nearly allied to living forms that it was difficult not to suspect that they had been connected by a common bond of descent. He therefore proposed that the element of time should enter into the definition of a species, and that it should run thus: "A species consists of individuals all resembling each other, and reproducing their like by generation, SO LONG AS THE SURROUNDING CONDITIONS DO NOT UNDERGO CHANGES SUFFICIENT TO CAUSE THEIR HABITS, CHARACTERS, AND FORMS TO VARY." He came at last to the conclusion that none of the animals and plants now existing were primordial creations, but were all derived from pre-existing forms, which, after they may have gone on for indefinite ages reproducing their like, had at length, by the influence of alterations in climate and in the animate world been made to vary gradually, and adapt themselves to new circumstances, some of them deviating in the course of ages so far from their original type as to have claims to be regarded as new species. In support of these views, he referred to wild and cultivated plants and to wild and domesticated animals, pointing out how their colour, form, structure, physiological attributes and even instincts were gradually modified by exposure to new soils and climates, new enemies, modes of subsistence, and kinds of food. Nor did he omit to notice that the newly acquired peculiarities may be inherited by the offspring for an indefinite series of generations, whether they be brought about naturally--as when a species, on the extreme verge of its geographical range, comes into competition with new antagonists and is subjected to new physical conditions; or artificially--as when by the act of the breeder or horticulturist peculiar varieties of form or disposition are selected. But Lamarck taught not only that species had been constantly undergoing changes from one geological period to another, but that there also had been a progressive advance of the organic world from the earliest to the latest times, from beings of the simplest to those of more and more complex structure, and from the lowest instincts up to the highest, and finally from brute intelligence to the reasoning powers of Man. The improvement in the grade of being had been slow and continuous, and the human race itself was at length evolved out of the most highly organised and endowed of the inferior mammalia. In order to explain how, after an indefinite lapse of ages, so many of the lowest grades of animal or plant still abounded, he imagined that the germs or rudiments of living things, which he called monads, were continually coming into the world and that there were different kinds of these monads for each primary division of the animal and vegetable kingdoms. This last hypothesis does not seem essentially different from the old doctrine of equivocal or spontaneous generation; it is wholly unsupported by any modern experiments or observation, and therefore affords us no aid whatever in speculating on the commencement of vital phenomena on the earth. Some of the laws which govern the appearance of new varieties were clearly pointed out by Lamarck. He remarked, for example, that as the muscles of the arm become strengthened by exercise or enfeebled by disuse, some organs may in this way, in the course of time, become entirely obsolete, and others previously weak become strong and play a new or more leading part in the organisation of a species. And so with instincts, where animals experience new dangers they become more cautious and cunning, and transmit these acquired faculties to their posterity. But not satisfied with such legitimate speculations, the French philosopher conceived that by repeated acts of volition animals might acquire new organs and attributes, and that in plants, which could not exert a will of their own, certain subtle fluids or organising forces might operate so as to work out analogous effects. After commenting on these purely imaginary causes, I pointed out in 1832, as the two great flaws in Lamarck's attempt to explain the origin of species, first, that he had failed to adduce a single instance of the initiation of a new organ in any species of animal or plant; and secondly, that variation, whether taking place in the course of nature or assisted artificially by the breeder and horticulturist, had never yet gone so far as to produce two races sufficiently remote from each other in physiological constitution as to be sterile when intermarried, or, if fertile, only capable of producing sterile hybrids, etc.* (* "Principles of Geology" 1st edition volume 2 chapter 2.) To this objection Lamarck would, no doubt, have answered that there had not been time for bringing about so great an amount of variation; for when Cuvier and some other of his contemporaries appealed to the embalmed animals and plants taken from Egyptian tombs, some of them 3000 years old, which had not experienced in that long period the slightest modification in their specific characters, he replied that the climate and soil of the valley of the Nile had not varied in the interval, and that there was therefore no reason for expecting that we should be able to detect any change in the fauna and flora. "But if," he went on to say, "the physical geography, temperature, and other conditions of life had been altered in Egypt as much as we know from geology has happened in other regions, some of the same animals and plants would have deviated so far from their pristine types as to be thought entitled to take rank as new and distinct species." Although I cited this answer of Lamarck in my account of his theory,* I did not at the time fully appreciate the deep conviction which it displays of the slow manner in which geological changes have taken place and the insignificance of thirty or forty centuries in the history of a species, and that, too, at a period when very narrow views were entertained of the extent of past time by most of the ablest geologists, and when great revolutions of the earth's crust, and its inhabitants, were generally attributed to sudden and violent catastrophes. (* Ibid. page 587.) While in 1832 I argued against Lamarck's doctrine of the gradual transmutation of one species into another, I agreed with him in believing that the system of changes now in progress in the organic world would afford, when fully understood, a complete key to the interpretation of all the vicissitudes of the living creation in past ages. I contended against the doctrine, then very popular, of the sudden destruction of vast multitudes of species and the abrupt ushering into the world of new batches of plants and animals. I endeavoured to sketch out (and it was, I believe, the first systematic attempt to accomplish such a task) the laws which govern the extinction of species, with a view of showing that the slow but ceaseless variations now in progress in physical geography, together with the migration of plants and animals into new regions, must in the course of ages give rise to the occasional loss of some of them and eventually cause an entire fauna and flora to die out; also that we must infer from geological data that the places thus left vacant from time to time are filled up without delay by new forms adapted to new conditions, sometimes by immigration from adjoining provinces, sometimes by new creations. Among the many causes of extinction enumerated by me were the power of hostile species, diminution of food, mutations in climate, the conversion of land into sea and of sea into land, etc. I firmly opposed Brocchi's hypothesis of a decline in the vital energy of each species;* maintaining that there was every reason to believe that the reproductive powers of the last surviving representatives of a species were as vigorous as those of their predecessors, and that they were as capable, under favourable circumstances, of repeopling the earth with their kind. (* "Principles of Geology" 1st edition volume 2 chapter 8; and 9th edition page 668.) The manner in which some species are now becoming scarce and dying out, one after the other, appeared to me to favour the doctrine of the fixity of the specific character, showing a want of pliancy and capability of varying, which ensured their annihilation whenever changes adverse to their well-being occurred; time not being allowed for such a transformation as might be conceived capable of adapting them to the new circumstances, and of converting them into what naturalists would call new species.* (* Laws of Extinction, "Principles of Geology" 1st edition 1832 volume 2 chapters 5 to 11 inclusive; and 9th edition chapters 37 to 42 inclusive 1853.) But while rejecting transmutation, I was equally opposed to the popular theory that the creative power had diminished in energy, or that it had been in abeyance ever since Man had entered upon the scene. That a renovating force which had been in full operation for millions of years should cease to act while the causes of extinction were still in full activity, or even intensified by the accession of Man's destroying power, seemed to me in the highest degree improbable. The only point on which I doubted was whether the force might not be intermittent instead of being, as Lamarck supposed, in ceaseless operation. Might not the births of new species, like the deaths of old ones, be sudden? Might they not still escape our observation? If the coming in of one new species, and the loss of one other which had endured for ages, should take place annually, still, assuming that there are a million of animals and plants living on the globe, it would require, I observed, a million of years to bring about a complete revolution in the fauna and flora. In that case, I imagined that, although the first appearance of a new form might be as abrupt as the disappearance of an old one, yet naturalists might never yet have witnessed the first entrance on the stage of a large and conspicuous animal or plant, and as to the smaller kinds, many of them may be conceived to have stolen in unseen, and to have spread gradually over a wide area, like species migrating into new provinces.* (* "Principles of Geology" 1st edition 1832 volume 2 chapter 11; and 9th edition page 706.) It may now be useful to offer some remarks on the very different reception which the twin branches of Lamarck's development theory, namely, progression and transmutation, have met with, and to inquire into the causes of the popularity of the one and the great unpopularity of the other. We usually test the value of a scientific hypothesis by the number and variety of the phenomena of which it offers a fair or plausible explanation. If transmutation, when thus tested, has decidedly the advantage over progression and yet is comparatively in disfavour, we may reasonably suspect that its reception is retarded, not so much by its own inherent demerits, as by some apprehended consequences which it is supposed to involve and which run counter to our preconceived opinions. THEORY OF PROGRESSION. In treating of this question, I shall begin with the doctrine of progression, a concise statement of which, so far as it relates to the animal kingdom, was thus given twelve years ago by Professor Sedgwick, in the preface to his "Discourse on the Studies of the University of Cambridge." "There are traces," he says, "among the old deposits of the earth of an organic progression among the successive forms of life. They are to be seen in the absence of mammalia in the older, and their very rare appearance in the newer Secondary groups; in the diffusion of warm-blooded quadrupeds (frequently of unknown genera) in the older Tertiary system, and in their great abundance (and frequently of known genera) in the upper portions of the same series; and lastly, in the recent appearance of Man on the surface of the earth." "This historical development," continues the same author, of the forms and functions of organic life during successive epochs, "seems to mark a gradual evolution of creative power, manifested by a gradual ascent towards a higher type of being." "But the elevation of the fauna of successive periods was not made by transmutation, but by creative additions; and it is by watching these additions that we get some insight into Nature's true historical progress, and learn that there was a time when Cephalopoda were the highest types of animal life, the primates of this world; that Fishes next took the lead, then Reptiles; and that during the secondary period they were anatomically raised far above any forms of the reptile class now living in the world. Mammals were added next, until Nature became what she now is, by the addition of Man."* (* Professor Sedgwick's "Discourse on the Studies of the University of Cambridge" Preface to 5th edition pages 44, 154, 216, 1850.) Although in the half century which has elapsed between the time of Lamarck and the publication of the above summary, new discoveries have caused geologists to assign a higher antiquity both to Man and the oldest fossil mammalia, fish, and reptiles than formerly, yet the generalisation, as laid down by the Woodwardian Professor, as to progression, still holds good in all essential particulars. The progressive theory was propounded in the following terms by the late Hugh Miller in his "Footprints of the Creator." "It is of itself an extraordinary fact without reference to other considerations, that the order adopted by Cuvier in his "Animal Kingdom," as that in which the four great classes of vertebrate animals, when marshalled according to their rank and standing, naturally range, should be also that in which they occur in order of time. The brain, which bears an average proportion to the spinal cord of not more than two to one, comes first--it is the brain of the fish; that which bears to the spinal cord an average proportion of two and a half to one succeeded it--it is the brain of the reptile; then came the brain averaging as three to one--it is that of the bird. Next in succession came the brain that averages as four to one--it is that of the mammal; and last of all there appeared a brain that averages as twenty-three to one--reasoning, calculating Man had come upon the scene."* (* "Footprints of the Creator" Edinburgh 1849 page 283.) M. Agassiz, in his "Essay on Classification," has devoted a chapter to the "Parallelism between the Geological Succession of Animals and Plants and their present relative Standing;" in which he has expressed a decided opinion that within the limits of the orders of each great class there is a coincidence between their relative rank in organisation and the order of succession of their representatives in time.* (* "Contributions to the Natural History of the United States" Part 1.--Essay on Classification page 108.) Professor Owen, in his Palaeontology, has advanced similar views, and has remarked, in regard to the vertebrata that there is much positive as well as negative evidence in support of the doctrine of an advance in the scale of being, from ancient to more modern geological periods. We observe, for example, in the Triassic, Oolitic, and Cretaceous strata, not only an absence of placental mammalia, but the presence of innumerable reptiles, some of large size, terrestrial and aquatic, herbivorous and predaceous, fitted to perform the functions now discharged by the mammalia. The late Professor Bronn, of Heidelberg, after passing in review more than 24,000 fossil animals and plants, which he had classified and referred each to their geological position in his "Index Palaeontologicus," came to the conclusion that, in the course of time, there had been introduced into the earth more and more highly organised types of animal and vegetable life; the modern species being, on the whole, more specialised, i.e. having separate organs, or parts of the body, to perform different functions, which, in the earlier periods and in beings of simpler structure, were discharged in common by a single part or organ. Professor Adolphe Brongniart, in an essay published in 1849 on the botanical classification and geological distribution of the genera of fossil plants,* arrives at similar results as to the progress of the vegetable world from the earliest periods to the present. (* Tableau des Genres de Vegetaux fossiles, etc. "Dictionnaire Universel d'Histoire Naturelle" Paris 1849.) He does not pretend to trace an exact historical series from the sea-weed to the fern, or from the fern again to the conifers and cycads, and lastly from those families to the palms and oaks, but he, nevertheless, points out that the cryptogamic forms, especially the acrogens, predominate among the fossils of the primary formations, the Carboniferous especially, while the gymnosperms or coniferous and cycadeous plants abound in all the strata, from the Trias to the Wealden inclusive; and lastly, the more highly developed angiosperms, both monocotyledonous and dicotyledonous, do not become abundant until the Tertiary period. It is a remarkable fact, as he justly observes, that the angiospermous exogens, which comprise four-fifths of living plants--a division to which all our native European trees, except the Coniferae, belong, and which embrace all the Compositae, Leguminosae, Umbelliferae, Cruciferae, Heaths, and so many other families--are wholly unrepresented by any fossils hitherto discovered in the Primary and Secondary formations from the Silurian to the Oolitic inclusive. It is not till we arrive at the Cretaceous period that they begin to appear, sparingly at first, and only playing a conspicuous part, together with the palms and other endogens, in the Tertiary epoch. When commenting on the eagerness with which the doctrine of progression was embraced from the close of the last century to the time when I first attempted, in 1830, to give some account of the prevailing theories in geology, I observed that far too much reliance was commonly placed on the received dates of the first appearances of certain orders or classes of animals or plants, such dates being determined by the age of the stratum in which we then happened to have discovered the earliest memorials of such types. At that time (1830), it was taken for granted that Man had not co-existed with the mammoth and other extinct mammalia, yet now that we have traced back the signs of his existence to the Pleistocene era, and may anticipate the finding of his remains on some future day in the Pliocene period, the theory of progression is not shaken; for we cannot expect to meet with human bones in the Miocene formations, where all the species and nearly all the genera of mammalia belong to types widely differing from those now living; and had some other rational being, representing Man, then flourished, some signs of his existence could hardly have escaped unnoticed, in the shape of implements of stone or metal, more frequent and more durable than the osseous remains of any of the mammalia. In the beginning of this century it was one of the canons of the popular geological creed that the first warm-blooded quadrupeds which had inhabited this planet were those derived from the Eocene gypsum of Montmartre in the suburbs of Paris, almost all of which Cuvier had shown to belong to extinct genera. This dogma continued in force for more than a quarter of a century, in spite of the discovery in 1818 of a marsupial quadruped in the Stonesfield strata, a member of the Lower Oolite, near Oxford. Some disputed the authority of Cuvier himself as to the mammalian character of the fossil; others, the accuracy of those who had assigned to it so ancient a place in the chronological series of rocks. In 1832 I pointed out that the occurrence of this single fossil in the Oolite was "fatal to the theory of successive development" as then propounded.* (* "Principles of Geology" 2nd edition 1 173.) Since that period great additions have been made to our knowledge of the existence of land quadrupeds in the olden times. We have ascertained that, in Eocene strata older than the gypsum of Paris, no less than four distinct sets of placental mammalia have flourished; namely, first, those of the Headon series in the Isle of Wight, from which fourteen species have been procured; secondly, those of the antecedent Bagshot and Bracklesham beds, which have yielded, together with the contemporaneous "calcaire grossier" of Paris, twenty species; thirdly, the still older beds of Kyson, near Ipswich, and those of Herne Bay, at the mouth of the Thames, in which seven species have been found; and fourthly, the Woolwich and Reading beds, which have supplied ten species.* (* Lyell's supplement to 5th edition of "Elements" 1857.) We can scarcely doubt that we should already have traced back the evidence of this class of fossils much farther had not our inquiries been arrested, first by the vast gap between the Tertiary and Secondary formations, and then by the marine nature of the Cretaceous rocks. The mammalia next in antiquity, of which we have any cognisance, are those of the Upper Oolite of Purbeck, discovered between the years 1854 and 1857, and comprising no less than fourteen species, referable to eight or nine genera; one of them, Plagiaulax, considered by Dr. Falconer to have been a herbivorous marsupial. The whole assemblage appear, from the joint observations of Professor Owen and Dr. Falconer, to indicate a low grade of quadruped, probably of the marsupial type. They were, for the most part, diminutive, the two largest not much exceeding our common hedgehog and polecat in size. Next anterior in age are the mammalia of the Lower Oolite of Stonesfield, of which four species are known, also very small and probably marsupial, with one exception, the Stereognathus ooliticus, which, according to Professor Owen's conjecture, may have been a hoofed quadruped and placental, though, as we have only half of the lower jaw with teeth, and the molars are unlike any living type, such an opinion is of course hazarded with due caution. Still older than the above are some fossil quadrupeds of small size, found in the Upper Trias of Stuttgart in Germany, and more lately by Mr. C. Moore in beds of corresponding age near Frome, which are also of a very low grade, like the living Myrmecobius of Australia. Beyond this limit our knowledge of the highest class of vertebrata does not as yet extend into the past, but the frequent shifting back of the old landmarks, nearly all of them once supposed in their turn to indicate the date of the first appearance of warm-blooded quadrupeds on this planet, should serve as a warning to us not to consider the goal at present reached by palaeontology as one beyond which they who come after us are never destined to pass. On the other hand, it may be truly said in favour of progression that after all these discoveries the doctrine is not gainsaid, for the less advanced marsupials precede the more perfect placental mammalia in the order of their appearance on the earth. If the three localities where the most ancient mammalia have been found--Purbeck, Stonesfield, and Stuttgart--had belonged all of them to formations of the same age, we might well have imagined so limited an area to have been peopled exclusively with pouched quadrupeds, just as Australia now is, while other parts of the globe were inhabited by placentals, for Australia now supports one hundred and sixty species of marsupials, while the rest of the continents and islands are tenanted by about seventeen hundred species of mammalia, of which only forty-six are marsupial, namely, the opossums of North and South America. But the great difference of age of the strata in each of these three localities seems to indicate the predominance throughout a vast lapse of time (from the era of the Upper Trias to that of the Purbeck beds) of a low grade of quadrupeds; and this persistency of similar generic and ordinal types in Europe while the species were changing, and while the fish, reptiles, and mollusca were undergoing vast modifications, raises a strong presumption that there was also a vast extension in space of the same marsupial forms during that portion of the Secondary epoch which has been termed "the age of reptiles." As to the class Reptilia, some of the orders which prevailed when the Secondary rocks were formed are confessedly much higher in their organisation than any of the same class now living. If the less perfect ophidians, or snakes, which now abound on the earth had taken the lead in those ancient days among the land reptiles, and the Deinosaurians had been contemporary with Man, there can be no doubt that the progressionist would have seized upon this fact with unfeigned satisfaction as confirmatory of his views. Now that the order of succession is precisely reversed, and that the age of the Iguanodon was long anterior to that of the Eocene Palaeophis and living boa, while the crocodile is in our own times the highest representative of its class, a retrograde movement in this important division of the vertebrata must be admitted. It may perhaps be accounted for by the power acquired by the placental mammalia, when they became dominant, a power before which the class of vertebrata next below them, as coming most directly in competition with them, may more than any other have given way. For no less than thirty-four years it had been a received axiom in palaeontology that reptiles had never existed before the Permian or Magnesian Limestone period, when at length in 1844 this supposed barrier was thrown down, and Carboniferous reptiles, terrestrial and aquatic, of several genera were brought to light; and discussions are now going on as to whether some remains of an Enaliosaur (perhaps a large Labyrinthodon) have not been detected in the coal of Nova Scotia, and whether certain sandstones near Elgin in Scotland, containing the bones of lacertian, crocodilian, and rhynchosaurian reptiles, may not be referable to the "Old Red" or Devonian group. Still, no traces of this class have yet been detected in rocks as ancient as those in which the oldest fish have been found. [38] As to fossil representatives of the ichthyic type, the most ancient were not supposed before 1838 to be of a date anterior to the Coal, but they have since been traced back, first to the Devonian, and then to the Silurian rocks. No remains, however, of them or of any vertebrate animal have yet been discovered in the Ordovician strata, rich as these are in invertebrate fossils, nor in the still older Cambrian; so that we seem authorised to conclude, though not without considerable reserve, that the vertebrate type was extremely scarce, if not wholly wanting, in those epochs often spoken of as "primitive," but which, if the Development Theory be true, were probably the last of a long series of antecedent ages in which living beings flourished. As to the Mollusca, which afford the most unbroken series of geological medals, the highest of that class, the Cephalopoda, abounded in older Silurian times, comprising several hundred species of chambered univalves. Had there been strong prepossessions against the progressive theory, it would probably have been argued that when these cephalopods abounded, and the siphonated gasteropods were absent, a higher order of zoophagous mollusca discharged the functions afterwards performed by an inferior order in the Secondary, Tertiary, and Post-Tertiary seas. But I have never seen this view suggested as adverse to the doctrine of progress, although much stress has been laid on the fact that the Silurian Brachiopoda, creatures of a lower grade, formerly discharged the functions of the existing lamellibranchiate bivalves, which are higher in the scale. It is said truly that the Ammonite, Orthoceras, and Nautilus of these ancient rocks were of the tetrabranchiate division, and none of them so highly organised as the Belemnite and other dibranchiate cephalopods which afterwards appeared, and some of which now flourish in our seas. Therefore, we may infer that the simplest forms of the Cephalopoda took precedence of the more complex in time. But if we embrace this view, we must not forget that there are living Cephalopoda, such as the Octopods, which are devoid of any hard parts, whether external or internal, and which could leave behind them no fossil memorials of their existence, so that we must make a somewhat arbitrary assumption, namely, that at a remote era, no such Dibranchiata were in being, in order to avail ourselves of this argument in favour of progression. On the other hand, it is true that in the Lower Cambrian not even the shell-bearing tetrabranchiates have yet been discovered. In regard to plants, although the generalisation above cited of M. Adolphe Brongniart is probably true, there has been a tendency in the advocates of progression to push the inferences deducible from known facts, in support of their favourite dogma, somewhat beyond the limits which the evidence justifies. Dr. Hooker observes, in his recent "Introductory Essay to the Flora of Australia," that it is impossible to establish a parallel between the successive appearances of vegetable forms in time, and their complexity of structure or specialisation of organs as represented by the successively higher groups in the natural method of classification. He also adds that the earliest recognisable Cryptogams are not only the highest now existing, but have more highly differentiated vegetative organs than any subsequently appearing, and that the dicotyledonous embryo and perfect exogenous wood, with the highest specialised tissue known (the coniferous with glandular tissue), preceded the monocotyledonous embryo and endogenous wood in date of appearance on the globe--facts wholly opposed to the doctrine of progression, and which can only be set aside on the supposition that they are fragmentary evidence of a time farther removed from the origin of vegetation than from the present day.* (* "Introductory Essay to the Flora of Australia," page 31 London 1859. Published separately.) [39] It would be an easy task to multiply objections to the theory now under consideration; but from this I refrain, as I regard it not only as a useful, but rather in the present state of science as an indispensable hypothesis, and one which though destined hereafter to undergo many and great modifications will never be overthrown. It may be thought almost paradoxical that writers who are most in favour of transmutation (Mr. C. Darwin and Dr. J. Hooker, for example) are nevertheless among those who are most cautious, and one would say timid, in their mode of espousing the doctrine of progression; while, on the other hand, the most zealous advocates of progression are oftener than not very vehement opponents of transmutation. We might have anticipated a contrary leaning on the part of both, for to what does the theory of progression point? It supposes a gradual elevation in grade of the vertebrate type in the course of ages from the most simple ichthyic form to that of the placental mammalia and the coming upon the stage last in the order of time of the most anthropomorphous mammalia, followed by the human race--this last thus appearing as an integral part of the same continuous series of acts of development, one link in the same chain, the crowning operation as it were of one and the same series of manifestations of creative power. If the dangers apprehended from transmutation arise from the too intimate connection which it tends to establish between the human and merely animal natures, it might have been expected that the progressive development of organisation, instinct, and intelligence might have been unpopular, as likely to pioneer the way for the reception of the less favoured doctrine. But the true explanation of the seeming anomaly is this, that no one can believe in transmutation who is not profoundly convinced that all we know in palaeontology is as nothing compared with what we have yet to learn, and they who regard the record as so fragmentary, and our acquaintance with the fragments which are extant as so rudimentary, are apt to be astounded at the confidence placed by the progressionists in data which must be defective in the extreme. But exactly in proportion as the completeness of the record and our knowledge of it are overrated, in that same degree are many progressionists unconscious of the goal towards which they are drifting. Their faith in the fullness of the annals leads them to regard all breaks in the series of organic existence, or in the sequence of the fossiliferous rocks, as proofs of original chasms and leaps in the course of nature--signs of the intermittent action of the creational force, or of catastrophes which devastated the habitable surface. They do not doubt that there is a continuity of plan, but they believe that it exists in the Divine mind alone, and they are therefore without apprehension that any facts will be discovered which would imply a material connection between the outgoing organisms and the incoming ones. CHAPTER 21. -- ON THE ORIGIN OF SPECIES BY VARIATION AND NATURAL SELECTION. Mr. Darwin's Theory of the Origin of Species by Natural Selection. Memoir by Mr. Wallace. Manner in which favoured Races prevail in the Struggle for Existence. Formation of new Races by breeding. Hypotheses of definite and indefinite Modifiability equally arbitrary. Competition and Extinction of Races. Progression not a necessary Accompaniment of Variation. Distinct Classes of Phenomena which Natural Selection explains. Unity of Type, Rudimentary Organs, Geographical Distribution, Relation of the extinct to the living Fauna and Flora, and mutual Relations of successive Groups of Fossil Forms. Light thrown on Embryological Development by Natural Selection. Why large Genera have more variable Species than small ones. Dr. Hooker on the Evidence afforded by the Vegetable Kingdom in favour of Creation by Variation. Steenstrup on alternation of Generations. How far the Doctrine of Independent Creation is opposed to the Laws now governing the Migration of Species. For many years after the promulgation of Lamarck's doctrine of progressive development, geologists were much occupied with the question whether the past changes in the animate and inanimate world were brought about by sudden and paroxysmal action, or gradually and continuously, by causes differing neither in kind nor degree from those now in operation. The anonymous author of "The Vestiges of Creation" published in 1844 a treatise, written in a clear and attractive style, which made the English public familiar with the leading views of Lamarck on transmutation and progression, but brought no new facts or original line of argument to support those views, or to combat the principal objections which the scientific world entertained against them. No decided step in this direction was made until the publication in 1858 of two papers, one by Mr. Darwin and another by Mr. Wallace, followed in 1859 by Mr. Darwin's celebrated work on "The Origin of Species by Means of Natural Selection; or, the Preservation of favoured Races in the Struggle for Life." The author of this treatise had for twenty previous years strongly inclined to believe that variation and the ordinary laws of reproduction were among the secondary causes always employed by the Author of nature, in the introduction from time to time of new species into the world, and he had devoted himself patiently to the collecting of facts and making of experiments in zoology and botany, with a view of testing the soundness of the theory of transmutation. Part of the manuscript of his projected work was read to Dr. Hooker as early as 1844 and some of the principal results were communicated to me on several occasions. [40] Dr. Hooker and I had repeatedly urged him to publish without delay, but in vain, as he was always unwilling to interrupt the course of his investigations; until at length Mr. Alfred R. Wallace, who had been engaged for years in collecting and studying the animals of the East Indian archipelago, thought out independently for himself one of the most novel and important of Mr. Darwin's theories. This he embodied in an essay "On the Tendency of Varieties to depart indefinitely from the original Type." It was written at Ternate in February 1858, and sent to Mr. Darwin with a request that it might be shown to me if thought sufficiently novel and interesting. Dr. Hooker and I were of opinion that it should be immediately printed, and we succeeded in persuading Mr. Darwin to allow one of the manuscript chapters of his "Origin of Species," entitled "On the Tendency of Species to form Varieties, and on the Perpetuation of Species and Varieties by natural Means of Selection," to appear at the same time.* (* See "Proceedings of the Linnaean Society" 1858.) By reference to these memoirs it will be seen that both writers begin by applying to the animal and vegetable worlds the Malthusian doctrine of population, or its tendency to increase in a geometrical ratio, while food can only be made to augment even locally in an arithmetical one. There being therefore no room or means of subsistence for a large proportion of the plants and animals which are born into the world, a great number must annually perish. Hence there is a constant struggle for existence among the individuals which represent each species and the vast majority can never reach the adult state, to say nothing of the multitudes of ova and seeds which are never hatched or allowed to germinate. Of birds it is estimated that the number of those which die every year equals the aggregate number by which the species to which they respectively belong is on the average permanently represented. The trial of strength which must decide what individuals are to survive and what to succumb occurs in the season when the means of subsistence are fewest, or enemies most numerous, or when the individuals are enfeebled by climate or other causes; and it is then that those varieties which have any, even the slightest, advantage over others come off victorious. They may often owe their safety to what would seem to a casual observer a trifling difference, such as a darker or lighter shade of colour rendering them less visible to a species which preys upon them, or sometimes to attributes more obviously advantageous, such as greater cunning or superior powers of flight or swiftness of foot. These peculiar qualities and faculties, bodily and instinctive, may enable them to outlive their less favoured rivals, and being transmitted by the force of inheritance to their offspring will constitute new races, or what Mr. Darwin calls "incipient species." If one variety, being in other respects just equal to its competitors, happens to be more prolific, some of its offspring will stand a greater chance of being among those which will escape destruction, and their descendants, being in like manner very fertile, will continue to multiply at the expense of all less prolific varieties. As breeders of domestic animals, when they choose certain varieties in preference to others to breed from, speak technically of their method as that of "selecting," Mr. Darwin calls the combination of natural causes, which may enable certain varieties of wild animals or plants to prevail over others of the same species, "natural selection." A breeder finds that a new race of cattle with short horns or without horns may be formed in the course of several generations by choosing varieties having the most stunted horns as his stock from which to breed; so nature, by altering in the course of ages, the conditions of life, the geographical features of a country, its climate, the associated plants and animals, and consequently the food and enemies of a species and its mode of life, may be said, by this means to select certain varieties best adapted for the new state of things. Such new races may often supplant the original type from which they have diverged, although that type may have been perpetuated without modification for countless anterior ages in the same region, so long as it was in harmony with the surrounding conditions then prevailing. Lamarck, when speculating on the origin of the long neck of the giraffe, imagined that quadruped to have stretched himself up in order to reach the boughs of lofty trees, until by continued efforts and longing to reach higher he obtained an elongated neck. Mr. Darwin and Mr. Wallace simply suppose that, in a season of scarcity, a longer-necked variety, having the advantage in this respect over most of the herd, as being able to browse on foliage out of their reach, survived them and transmitted its peculiarity of cervical conformation to its successors. By the multiplying of slight modifications in the course of thousands of generations and by the handing down of the newly-acquired peculiarities by inheritance, a greater and greater divergence from the original standard is supposed to be effected, until what may be called a new species, or in a greater lapse of time a new genus will be the result. Every naturalist admits that there is a general tendency in animals and plants to vary; but it is usually taken for granted, though he have no means of proving the assumption to be true, that there are certain limits beyond which each species cannot pass under any circumstances or in any number of generations. Mr. Darwin and Mr. Wallace say that the opposite hypothesis, which assumes that every species is capable of varying indefinitely from its original type, is not a whit more arbitrary, and has this manifest claim to be preferred, that it will account for a multitude of phenomena which the ordinary theory is incapable of explaining. We have no right, they say, to assume, should we find that a variable species can no longer be made to vary in a certain direction, that it has reached the utmost limit to which it might under more favourable conditions or if more time were allowed be made to diverge from the parent type. Hybridisation is not considered by Mr. Darwin as a cause of new species, but rather as tending to keep variation within bounds. Varieties which are nearly allied cross readily with each other, and with the parent stock, and such crossing tends to keep the species true to its type, while forms which are less nearly related, although they may intermarry, produce no mule offspring capable of perpetuating their kind. The competition of races and species, observes Mr. Darwin, is always most severe between those which are most closely allied and which fill nearly the same place in the economy of nature. Hence when the conditions of existence are modified the original stock runs great risk of being superseded by some one of its modified offshoots. The new race or species may not be absolutely superior in the sum of its powers and endowments to the parent stock, and may even be more simple in structure and of a lower grade of intelligence, as well as of organisation, provided on the whole it happens to have some slight advantage over its rivals. Progression, therefore, is not a necessary accompaniment of variation and natural selection, though when a higher organisation happens to be coincident with superior fitness to new conditions, the new species will have greater power and a greater chance of permanently maintaining and extending its ground. One of the principal claims of Mr. Darwin's theory to acceptance is that it enables us to dispense with a law of progression as a necessary accompaniment of variation. It will account equally well for what is called degradation, or a retrograde movement towards a simpler structure, and does not require Lamarck's continual creation of monads; for this was a necessary part of his system, in order to explain how, after the progressive power had been at work for myriads of ages, there were as many beings of the simplest structure in existence as ever. Mr. Darwin argues, and with no small success, that all true classification in zoology and botany is in fact genealogical, and that community of descent is the hidden bond which naturalists have been unconsciously seeking, while they often imagined that they were looking for some unknown plan of creation. As the "Origin of Species"* is in itself a condensed abstract of a much larger work not yet published [41] I could not easily give an analysis of its contents within narrower limits than those of the original, but it may be useful to enumerate briefly some of the principal classes of phenomena on which the theory of "natural selection" would throw light. (* "Origin of Species" page 121.) In the first place it would explain, says Mr. Darwin, the unity of type which runs through the whole organic world, and why there is sometimes a fundamental agreement in structure in the same class of beings which is quite independent of their habits of life, for such structure, derived by inheritance from a remote progenitor, has been modified in the course of ages in different ways according to the conditions of existence. It would also explain why all living and extinct beings are united, by complex radiating and circuitous lines of affinity with one another into one grand system;* also, there having been a continued extinction of old races and species in progress and a formation of new ones by variation, why in some genera which are largely represented, or to which a great many species belong, many of these are closely but unequally related; also, why there are distinct geographical provinces of species of animals and plants, for after long isolation by physical barriers each fauna and flora by varying continually must become distinct from its ancestral type, and from the new forms assumed by other descendants which have diverged from the same stock. (* "Origin" page 498.) The theory of indefinite modification would also explain why rudimentary organs are so useful in classification, being the remnants preserved by inheritance of organs which the present species once used--as in the case of the rudiments of eyes in insects and reptiles inhabiting dark caverns, or of the wings of birds and beetles which have lost all power of flight. In such cases the affinities of species are often more readily discerned by reference to these imperfect structures than by others of much more physiological importance to the individuals themselves. The same hypothesis would explain why there are no mammalia in islands far from continents, except bats, which can reach them by flying; and also why the birds, insects, plants, and other inhabitants of islands, even when specifically unlike, usually agree generically with those of the nearest continent, it being assumed that the original stock of such species came by migration from the nearest land. Variation and natural selection would also afford a key to a multitude of geological facts otherwise wholly unaccounted for, as for example why there is generally an intimate connection between the living animals and plants of each great division of the globe and the extinct fauna and flora of the Post-Tertiary or Tertiary formations of the same region; as, for example, in North America, where we not only find among the living mollusca peculiar forms foreign to Europe, such as Gnathodon and Fulgur (a subgenus of Fusus), but meet also with extinct species of those same genera in the Tertiary fauna of the same part of the world. In like manner, among the mammalia we find in Australia not only living kangaroos and wombats, but fossil individuals of extinct species of the same genera. So also there are recent and fossil sloths, armadilloes and other Edentata in South America, and living and extinct species of elephant, rhinoceros, tiger, and bear in the great Europeo-Asiatic continent. The theory of the origin of new species by variation will also explain why a species which has once died out never reappears and why the fossil fauna and flora recede farther and farther from the living type in proportion as we trace them back to remoter ages. It would also account for the fact that when we have to intercalate a new set of fossiliferous strata between two groups previously known, the newly discovered fossils serve to fill up gaps between specific or generic types previously familiar to us, supplying often the missing links of the chain, which, if transmutation is accepted, must once have been continuous. One of the most original speculations in Mr. Darwin's work is derived from the fact that, in the breeding of animals, it is often observed that at whatever age any variation first appears in the parent, it tends to reappear at a corresponding age in the offspring. Hence the young individuals of two races which have sprung from the same parent stock are usually more like each other than the adults. Thus the puppies of the greyhound and bull-dog are much more nearly alike in their proportions than the grown-up dogs, and in like manner the foals of the carthorse and racehorse than the adult individuals. For the same reason we may understand why the species of the same genus, or genera of the same family, resemble each other more nearly in their embryonic than in their more fully developed state, or how it is that in the eyes of most naturalists the structure of the embryo is even more important in classification than that of the adult, "for the embryo is the animal in its less modified state, and in so far it reveals the structure of its progenitor. In two groups of animals, however much they may at present differ from each other in structure and habits, if they pass through the same or similar embryonic stages, we may feel assured that they have both descended from the same or nearly similar parents, and are therefore in that degree closely related. Thus community in embryonic structure reveals community of descent, however much the structure of the adult may have been modified."* (* Darwin, "Origin" etc. page 448.) If then there had been a system of progressive development, the successive changes through which the embryo of a species of a high class, a mammifer for example, now passes, may be expected to present us with a picture of the stages through which, in the course of ages, that class of animals has successively passed in advancing from a lower to a higher grade. Hence the embryonic states exhibited one after the other by the human individual bear a certain amount of resemblance to those of the fish, reptile, and bird before assuming those of the highest division of the vertebrata. Mr. Darwin, after making a laborious analysis of many floras, found that those genera which are represented by a large number of species contain a greater number of variable species, relatively speaking, than the smaller genera or those less numerously represented. This fact he adduces in support of his opinion that varieties are incipient species, for he observes that the existence of the larger genera implies that the manufacturing of species has been active in the period immediately preceding our own, in which case we ought generally to find the same forces still in full activity, more especially as we have every reason to believe the process by which new species are produced is a slow one.* (* "Origin of Species" chapter 2 page 56.) Dr. Hooker tells us that he was long disposed to doubt this result, as he was acquainted with so many variable small genera, but after examining Mr. Darwin's data, he was compelled to acquiesce in his generalisation.* (* "Introductory Essay to the Flora of Australia" page 6.) It is one of those conclusions, to verify which requires the investigation of many thousands of species, and to which exceptions may easily be adduced both in the animal and vegetable kingdoms, so that it will be long before we can expect it to be thoroughly tested, and if true, fairly appreciated. Among the most striking exceptions will be some genera still large, but which are beginning to decrease, the conditions favourable to their former predominance having already begun to change. To many, this doctrine of "natural selection," or "the preservation of favoured races in the struggle for life," seems so simple, when once clearly stated, and so consonant with known facts and received principles, that they have difficulty in conceiving how it can constitute a great step in the progress of science. Such is often the case with important discoveries, but in order to assure ourselves that the doctrine was by no means obvious, we have only to refer back to the writings of skilful naturalists who attempted in the earlier part of the nineteenth century to theorise on this subject, before the invention of this new method of explaining how certain forms are supplanted by new ones and in what manner these last are selected out of innumerable varieties and rendered permanent. DR. HOOKER ON THE THEORY OF "CREATION BY VARIATION" AS APPLIED TO THE VEGETABLE KINGDOM. Of Dr. Hooker, whom I have often cited in this chapter, Mr. Darwin has spoken in the Introduction to his "Origin of Species," as one "who had, for fifteen years, aided him in every possible way, by his large stores of knowledge, and his excellent judgment." This distinguished botanist published his "Introductory Essay to the Flora of Australia" in December 1859, the year after the memoir on "Natural Selection" was communicated to the Linnaean Society, and a month after the appearance of the "Origin of Species." Having, in the course of his extensive travels, studied the botany of arctic, temperate, and tropical regions, and written on the flora of India, which he had examined at all heights above the sea from the plains of Bengal to the limits of perpetual snow in the Himalaya, and having specially devoted his attention to "geographical varieties," or those changes of character which plants exhibit when traced over wide areas and seen under new conditions; being also practically versed in the description and classification of new plants, from various parts of the world, and having been called upon carefully to consider the claims of thousands of varieties to rank as species, no one was better qualified by observation and reflection to give an authoritative opinion on the question, whether the present vegetation of the globe is or is not in accordance with the theory which Mr. Darwin has proposed. We cannot but feel, therefore, deeply interested when we find him making the following declaration: "The mutual relations of the plants of each great botanical province, and, in fact, of the world generally, is just such as would have resulted if variation had gone on operating throughout indefinite periods, in the same manner as we see it act in a limited number of centuries, so as gradually to give rise in the course of time, to the most widely divergent forms." In the same essay, this author remarks, "The element of mutability pervades the whole Vegetable Kingdom; no class, nor order, nor genus of more than a few species claims absolute exemption from it, whilst the grand total of unstable forms, generally assumed to be species, probably exceeds that of the stable." Yet he contends that species are neither visionary, nor even arbitrary creations of the naturalist, but realities, though they may not remain true for ever. The majority of them, he remarks, are so far constant, "within the range of our experience," and their forms and characters so faithfully handed down through thousands of generations, that they admit of being treated as if they were permanent and immutable. But the range of "our experience" is so limited, that it will "not account for a single fact in the present geographical distribution, or origin of any one species of plant, nor for the amount of variation it has undergone, nor will it indicate the time when it first appeared, nor the form it had when created."* (* Hooker, "Introductory Essay to the Flora of Australia.") To what an extent the limits of species are indefinable, is evinced, he says, by the singular fact that, among those botanists who believe them to be immutable, the number of flowering plants is by some assumed to be 80,000, and by others over 150,000. The general limitation of species to certain areas suggests the idea that each of them, with all their varieties, have sprung from a common parent and have spread in various directions from a common centre. The frequency also of the grouping of genera within certain geographical limits is in favour of the same law, although the migration of species may sometimes cause apparent exceptions to the rule and make the same types appear to have originated independently at different spots.* (* Ibid. page 13.) Certain genera of plants, which, like the brambles, roses, and willows in Europe, consist of a continuous series of varieties between the terms of which no intermediate forms can be intercalated, may be supposed to be newer types and on the increase, and therefore undergoing much variation; whereas genera which present no such perplexing gradations may be of older date and may have been losing species and varieties by extinction. In this case, the annihilation of intermediate forms which once existed makes it an easy task to distinguish those which remain. It had usually been supposed by the advocates of the immutability of species that domesticated races, if allowed to run wild, always revert to their parent type. Mr. Wallace had said in reply that a domesticated species, if it loses the protection of Man, can only stand its ground in a wild state by resuming those habits and recovering those attributes which it may have lost when under domestication. If these faculties are so much enfeebled as to be irrecoverable it will perish; if not and if it can adapt itself to the surrounding conditions, it will revert to the state in which Man first found it: for in one, two, or three thousand years, which may have elapsed since it was originally tamed, there will not have been time for such geographical, climatal, and organic changes as would only be suited to a new race or a new and allied species. But in regard to plants Dr. Hooker questions the fact of reversion. According to him, species in general do not readily vary, but when they once begin to do so the new varieties, as every horticulturist knows, show a great inclination to go on departing more and more from the old stock. As the best marked varieties of a wild species occur on the confines of the area which it inhabits, so the best marked varieties of a cultivated plant are those last produced by the gardener. Cabbages, for example, wall fruits, and cereal, show no disposition, when neglected, to assume the characters of the wild states of these plants. Hence the difficulty of determining what are the true parent species of most of our cultivated plants. Thus the finer kinds of apples, if grown from seed, degenerate and become crabs, but in so doing they do not revert to the original wild crab-apple, but become crab states of the varieties to which they belong.* (* "Introductory Essay to the Flora of Australia" page 9.) It would lead me into too long a digression were I to attempt to give a fuller analysis of this admirable essay; but I may add that none of the observations are more in point, as bearing on the doctrine of what Hooker terms "creation by variation," than the great extent to which the internal characters and properties of plants, or their physiological constitution, are capable of being modified, while they exhibit externally no visible departure from the normal form. Thus, in one region a species may possess peculiar medicinal qualities which it wants in another, or it may be hardier and better able to resist cold. The average range in altitude, says Hooker, of each species of flowering plant in the Himalayan Mountains, whether in the tropical, temperate, or Alpine region, is 4000 feet, which is equivalent to twelve degrees of isothermals of latitude. If an individual of any of these species be taken from the upper limits of its range and carried to England, it is found to be better able to stand our climate than those from the lower or warmer stations. When several of these internal or physiological modifications are accompanied by variation in size, habits of growth, colour of the flowers, and other external characters, and these are found to be constant in successive generations, botanists may well begin to differ in opinion as to whether they ought to regard them as distinct species or not. ALTERNATION OF GENERATIONS. Hitherto, no rival hypothesis has been proposed as a substitute for the doctrine of transmutation; for what we term "independent creation," or the direct intervention of the Supreme Cause, must simply be considered as an avowal that we deem the question to lie beyond the domain of science. The discovery by Steenstrup of alternate generation enlarges our views of the range of metamorphosis through which a species may pass, so that some of its stages (as when a Sertularia and a Medusa interchange) deviate so far from others as to have been referred by able zoologists to distinct genera, or even families. But in all these cases the organism, after running through a certain cycle of change, returns to the exact point from which it set out, and no new form or species is thereby introduced into the world. The only secondary cause therefore which has as yet been even conjecturally brought forward, to explain how in the ordinary course of nature a new specific form may be generated is, as Lamarck declared, "variation," and this has been rendered a far more probable hypothesis by the way in which "natural selection" is shown to give intensity and permanency to certain varieties. INDEPENDENT CREATION. When I formerly advocated the doctrine that species were primordial creations and not derivative, I endeavoured to explain the manner of their geographical distribution, and the affinity of living forms to the fossil types nearest akin to them in the Tertiary strata of the same part of the globe, by supposing that the creative power, which originally adapts certain types to aquatic and others to terrestrial conditions, has at successive geological epochs introduced new forms best suited to each area and climate, so as to fill the places of those which may have died out. In that case, although the new species would differ from the old (for these would not be revived, having been already proved by the fact of their extinction to be incapable of holding their ground), still they would resemble their predecessors generically. For, as Mr. Darwin states in regard to new races, those of a dominant type inherit the advantages which made their parent species flourish in the same country, and they likewise partake in those general advantages which made the genus to which the parent species belonged a large genus in its own country. We might therefore, by parity of reasoning, have anticipated that the creative power, adapting the new types to the new combination of organic and inorganic conditions of a given region, such as its soil, climate, and inhabitants, would introduce new modifications of the old types--marsupials, for example, in Australia, new sloths and armadilloes in South America, new heaths at the Cape, new roses in the northern and new calceolarias in the southern hemisphere. But to this line of argument Mr. Darwin and Dr. Hooker reply that when animals or plants migrate into new countries, whether assisted by man or without his aid, the most successful colonisers appertain by no means to those types which are most allied to the old indigenous species. On the contrary it more frequently happens that members of genera, orders, or even classes, distinct and foreign to the invaded country, make their way most rapidly and become dominant at the expense of the endemic species. Such is the case with the placental quadrupeds in Australia, and with horses and many foreign plants in the pampas of South America, and numberless instances in the United States and elsewhere which might easily be enumerated. Hence the transmutationists infer that the reason why these foreign types, so peculiarly fitted for these regions, have never before been developed there is simply that they were excluded by natural barriers. But these barriers of sea or desert or mountain could never have been of the least avail had the creative force acted independently of material laws or had it not pleased the Author of Nature that the origin of new species should be governed by some secondary causes analogous to those which we see preside over the appearance of new varieties, which never appear except as the offspring of a parent stock very closely resembling them. CHAPTER 22. -- OBJECTIONS TO THE HYPOTHESIS OF TRANSMUTATION CONSIDERED. Statement of Objections to the Hypothesis of Transmutation founded on the Absence of Intermediate Forms. Genera of which the Species are closely allied. Occasional Discovery of the missing Links in a Fossil State. Davidson's Monograph on the Brachiopoda. Why the Gradational Forms, when found, are not accepted as Evidence of Transmutation. Gaps caused by Extinction of Races and Species. Vast Tertiary Periods during which this Extinction has been going on in the Fauna and Flora now existing. Genealogical Bond between Miocene and Recent Plants and Insects. Fossils of Oeningen. Species of Insects in Britain and North America represented by distinct Varieties. Falconer's Monograph on living and fossil Elephants. Fossil Species and Genera of the Horse Tribe in North and South America. Relation of the Pliocene Mammalia of North America, Asia, and Europe. Species of Mammalia, though less persistent than the Mollusca, change slowly. Arguments for and against Transmutation derived from the Absence of Mammalia in Islands. Imperfection of the Geological Record. Intercalation of newly discovered Formation of intermediate Age in the chronological Series. Reference of the St. Cassian Beds to the Triassic Periods. Discovery of new organic Types. Feathered Archaeopteryx of the Oolite. THEORY OF TRANSMUTATION--ABSENCE OF INTERMEDIATE LINKS. The most obvious and popular of the objections urged against the theory of transmutation may be thus expressed: If the extinct species of plants and animals of the later geological periods were the progenitors of the living species, and gave origin to them by variation and natural selection, where are all the intermediate forms, fossil and living, through which the lost types must have passed during their conversion into the living ones? And why do we not find almost everywhere passages between the nearest allied species and genera, instead of such strong lines of demarcation and often wide intervening gaps? We may consider this objection under two heads:-- First. To what extent are the gradational links really wanting in the living creation or in the fossil world, and how far may we expect to discover such as are missing by future research? Secondly. Are the gaps more numerous than we ought to anticipate, allowing for the original defective state of the geological records, their subsequent dilapidation and our slight acquaintance with such parts of them as are extant, and allowing also for the rate of extinction of races and species now going on, and which has been going on since the commencement of the Tertiary period? First. As to the alleged absence of intermediate varieties connecting one species with another, every zoologist and botanist who has engaged in the task of classification has been occasionally thrown into this dilemma--if I make more than one species in this group, I must, to be consistent, make a great many. Even in a limited region like the British Isles this embarrassment is continually felt. Scarcely any two botanists, for example, can agree as to the number of roses, still less as to how many species of bramble we possess. Of the latter genus, Rubus, there is one set of forms respecting which it is still a question whether it ought to be regarded as constituting three species or thirty-seven. Mr. Bentham adopts the first alternative and Mr. Babington the second, in their well-known treatises on British plants. We learn from Dr. Hooker that at the antipodes, both in New Zealand and Australia, this same genus Rubus is represented by several species rich in individuals and remarkable for their variability. When we consider how, as we extend our knowledge of the same plant over a wider area, new geographical varieties commonly present themselves, and then endeavour to imagine the number of forms of the genus Rubus which may now exist, or probably have existed, in Europe and in regions intervening between Europe and Australia, comprehending all which may have flourished in Tertiary and Post-Tertiary periods, we shall perceive how little stress should be laid on arguments founded on the assumed absence of missing links in the flora as it now exists. If in the battle of life the competition is keenest between closely allied varieties and species, as Mr. Darwin contends, many forms can never be of long duration, nor have a wide range, and these must often pass away without leaving behind them any fossil memorials. In this manner we may account for many breaks in the series which no future researches will ever fill up. DAVIDSON ON FOSSIL BRACHIOPODA. It is from fossil conchology more than from any other department of the organic world that we may hope to derive traces of a transition from certain types to others, and fossil memorials of all the intermediate shades of form. We may especially hope to gain this information from the study of some of the lower groups, such as the Brachiopoda, which are persistent in type, so that the thread of our inquiry is less likely to be interrupted by breaks in the sequence of the fossiliferous rocks. The splendid monograph just concluded by Mr. Davidson on the British Brachiopoda, illustrates, in the first place, the tendency of certain generic forms in this division of the mollusca to be persistent throughout the whole range of geological time yet known to us; for the four genera, Rhynchonella, Crania, Discina, and Lingula, have been traced through the Silurian, Devonian, Carboniferous, Permian, Jurassic, Cretaceous, Tertiary, and Recent periods, and still retain in the existing seas the identical shape and character which they exhibited in the earliest formations. On the other hand, other Brachiopoda have gone through in shorter periods a vast series of transformations, so that distinct specific and even generic names have been given to the same varying form, according to the different aspects and characters it has put on in successive sets of strata. In proportion as materials of comparison have accumulated, the necessity of uniting species previously regarded as distinct under one denomination has become more and more apparent. Mr. Davidson, accordingly, after studying not less than 260 reputed species from the British Carboniferous rocks, has been obliged to reduce that number to 100, to which he has added 20 species either entirely new or new to the British strata; but he declares his conviction that, when our knowledge of these 120 Brachiopoda is more complete, a further reduction of species will take place. Speaking of one of these forms, which he calls Spirifer trigonalis, he says that it is so dissimilar to another extreme of the series, S. crassa, that in the first part of his memoir (published some ten years ago) he described them as distinct, and the idea of confounding them together must, he admits, appear absurd to those who have never seen the intermediate links, such as are presented by S. bisulcata, and at least four others with their varieties, most of them shells formerly recognised as distinct by the most eminent palaeontologists, but respecting which these same authorities now agree with Mr. Davidson in uniting them into one species.* (* "Monograph on British Brachiopoda" Palaeontographical Society page 222.) The same species has sometimes continued to exist under slightly modified forms throughout the whole of the Ordovician and Silurian as well as the entire Devonian and Carboniferous periods, as in the case of the shell generally known as Leptaena rhomboidalis, Wahlenberg. No less than fifteen commonly received species are demonstrated by Mr. Davidson by the aid of a long series of transitional forms, to appertain to this one type; and it is acknowledged by some of the best writers that they were induced on purely theoretical grounds to give distinct names to some of the varieties now suppressed, merely because they found them in rocks so widely remote in time that they deemed it contrary to analogy to suppose that the same species could have endured so long: a fallacious mode of reasoning, analogous to that which leads some zoologists and botanists to distinguish by specific names slight varieties of living plants and animals met with in very remote countries, as in Europe and Australia, for example; it being assumed that each species has had a single birthplace or area of creation, and that they could not by migration have gone from the northern to the southern hemisphere across the intervening tropics. Examples are also given by Mr. Davidson of species which pass from the Devonian into the Carboniferous, and from that again into the Permian rocks. The vast longevity of such specific forms has not been generally recognised in consequence of the change of names which they have undergone when derived from such distant formations, as when Atrypa unguicularis assumes, when derived from a Carboniferous rock, the name of Spirifer Urei, besides several other synonyms, and then, when it reaches the Permian period, takes the name of Spirifer Clannyana, King; all of which forms the author of the monograph, now under consideration, asserts to be one and the same. No geologist will deny that the distance of time which separates some of the eras above alluded to, or the dates of the earliest and latest appearances of some of the fossils above mentioned, must be reckoned by millions of years. According to Mr. Darwin's views, it is only by having at our command the records of such enormous periods that we can expect to be able to point out the gradations which unite very distinct specific forms. But the advocate of transmutation must not be disappointed if, when he has succeeded in obtaining some of the proofs which he was challenged to produce, they make no impression on the mind of his opponent. All that will be conceded is that specific variation in the Brachiopoda, at least, has a wider range than was formerly suspected. So long as several allied species were brought nearer and nearer to each other, considerable uneasiness might have been felt as to the reality of species in general, but when fifteen or more are once fairly merged in one group, constituting in the aggregate a single species, one and indivisible, and capable of being readily distinguished from every other group at present known, all misgivings are at an end. Implicit trust in the immutability of species is then restored, and the more insensible the shades from one extreme to the other, in a word, the more complete the evidence of transition, the more nugatory does the argument derived from it appear. It then simply resolves itself into one of those exceptional instances of what is called a protean form. Thirty years ago a great London dealer in shells, himself an able naturalist, told me that there was nothing he had so much reason to dread, as tending to depreciate his stock in trade, as the appearance of a good monograph on some large genus of mollusca; for, in proportion as the work was executed in a philosophical spirit, it was sure to injure him, every reputed species pronounced to be a mere variety becoming from that time unsaleable. Fortunately, so much progress has since been made in England in estimating the true ends and aims of science, that specimens indicating a passage between forms usually separated by wide gaps, whether in the Recent or fossil fauna, are eagerly sought for, and often more prized than the mere normal or typical forms. It is clear that the more ancient the existing mollusca, or the farther back into the past we can trace the remains of shells still living, the more easy it becomes to reconcile with the doctrine of transmutation the distinctness in character of the majority of living species. For, what we want is time, first, for the gradual formation, and then for the extinction of races and allied species, occasioning gaps between the survivors. In the year 1830 I announced, on the authority of M. Deshayes, that about one-fifth of the mollusca of the Falunian or Upper Miocene strata of Europe, belonged to living species. Although the soundness of that conclusion was afterwards called in question by two or three eminent conchologists (and by the late M. Alcide d'Orbigny among others), it has since been confirmed by the majority of living naturalists and is well borne out by the copious evidence on the subject laid before the public in the magnificent work edited by Dr. Hoernes, and published under the auspices of the Austrian Government, "On the Fossil Shells of the Vienna Basin." The collection of Tertiary shells from which those descriptions and beautiful figures were taken is almost unexampled for the fine state of preservation of the specimens, and the care with which all the varieties have been compared. It is now admitted that about one-third of these Miocene forms, univalves and bivalves included, agree specifically with living mollusca, so that much more than the enormous interval which divides the Miocene from the Recent period must be taken into our account when we speculate on the origin by transmutation of the shells now living, and the disappearance by extinction of intermediate varieties and species. MIOCENE PLANTS AND INSECTS RELATED TO RECENT SPECIES. Geologists were acquainted with about three hundred species of marine shells from the Falunian strata on the banks of the Loire, before they knew anything of the contemporary insects and plants. At length, as if to warn us against inferring from negative evidence the poverty of any ancient set of strata in organic remains proper to the land, a rich flora and entomological fauna was suddenly revealed to us characteristic of Central Europe during the Upper Miocene period. This result followed the determination of the true position of the Oeningen beds in Switzerland, and of certain formations of "Brown Coal" in Germany. Professor Heer, who has described nearly five hundred species of fossil plants from Oeningen, besides many more from other Miocene localities in Switzerland,* estimates the phanerogamous species which must have flourished in Central Europe at that time at 3000, and the insects as having been more numerous in the same proportion as they now exceed the plants in all latitudes. (* Heer, "Flora tertiaria Helvetiae" 1859; and Gaudin's French translation, with additions, 1861.) This European Miocene flora was remarkable for the preponderance of arborescent and shrubby evergreens, and comprised many generic types no longer associated together in any existing flora or geographical province. Some genera, for example, which are at present restricted to America, co-existed in Switzerland with forms now peculiar to Asia, and with others at present confined to Australia. Professor Heer has not ventured to identify any of this vast assemblage of Miocene plants and insects with living species, so far at least as to assign to them the same specific names, but he presents us with a list of what he terms homologous forms, which are so like the living ones that he supposes the one to have been derived genealogically from the others. He hesitates indeed as to the manner of the transformation or the precise nature of the relationship, "whether the changes were brought about by some influence exerted continually for ages, or whether at some given moment the old types were struck with a new image." Among the homologous plants alluded to are forty species, of which both the leaves and fruits are preserved, and thirty others, known at present by their leaves only. In the first list we find many American types, such as the tulip tree (Liriodendron), the deciduous cypress (Taxodium), the red maple and others, together with Japanese forms, such as a cinnamon, which is very abundant. And what is worthy of notice, some of these fossils so closely allied to living plants occur not only in the Upper, but even some few of them as far back in time as the Lower Miocene formations of Switzerland and Germany, which are probably as distant from the Upper Miocene or Oeningen beds as are the latter from our own era. Some of the fossil plants to which Professor Heer has given new names have been regarded as Recent species by other eminent naturalists. Thus, one of the trees allied to the elm Unger had called Planera Richardi, a species which now flourishes in the Caucasus and Crete. Professor Heer had attempted to distinguish it from the living tree by the greater size of its fruit, but this character he confessed did not hold good, when he had an opportunity (1861) of comparing all the varieties of the living Planera Richardi which Dr. Hooker laid before him in the rich herbarium of Kew. As to the "homologous insects" of the Upper Miocene period in Switzerland, we find among them, mingled with genera now wholly foreign to Europe, some very familiar forms, such as the common glowworm, Lampyris noctiluca, Linn., the dung-beetle, Geotrupes stercorarius, Linn., the ladybird, Coccinella septempunctata, Linn., the ear-wig, Forficula auricularia, Linn., some of our common dragon-flies, as Libellula depressa, Linn., the honey-bee, Apis mellifera, Linn., the cuckoo spittle insect, Aphrophora spumaria, Linn., and a long catalogue of others, to all of which Professor Heer had given new names, but which some entomologists may regard as mere varieties until some stronger reasons are adduced for coming to a contrary opinion. Several of the insects above enumerated, like the common ladybird, are well known at present to have a very wide range over nearly the whole of the Old World, for example, without varying, and might therefore be expected to have been persistent throughout many successive changes of the earth's surface and climate. Yet we may fairly anticipate that even the most constant types will have undergone some modifications in passing from the Miocene to the Recent epoch, since in the former period the geography and climate of Europe, the height of the Alps, and the general fauna and flora were so different from what they now are. But the deviation may not exceed that which would generally be expressed by what is called a well-marked variety. Before I pass on to another topic, it may be well to answer a question which may have occurred to the reader; how it happens that we remained so long ignorant of the vegetation and insects of the Upper Miocene period in Europe? The answer may be instructive to those who are in the habit of underrating the former richness of the organic world wherever they happen to have no evidence of its condition. A large part of the Upper Miocene insects and plants alluded to have been met with at Oeningen, near the Lake of Constance, in two or three spots embedded in thinly laminated marls, the entire thickness of which scarcely exceeds 3 or 4 feet, and in two quarries of very limited dimensions. The rare combination of causes which seems to have led to the faithful preservation of so many treasures of a perishable nature in so small an area, appear to have been the following: first, a river flowing into a lake; secondly, storms of wind, by which leaves and sometimes the boughs of trees were torn off and floated by the stream into the lake; thirdly, mephitic gases rising from the lake, by which insects flying over its surface were occasionally killed: and fourthly, a constant supply of carbonate of lime in solution from mineral springs, the calcareous matter when precipitated to the bottom mingling with fine mud and thus forming the fossiliferous marls. SPECIES OF INSECTS IN BRITAIN AND NORTH AMERICA, REPRESENTED BY DISTINCT VARIETIES. If we compare the living British insects with those of the American continent, we frequently find that even those species which are considered to be identical, are nevertheless varieties of the European types. I have noticed this fact when speaking of the common English butterfly, Vanessa atalanta, or "red admiral," which I saw flying about the woods of Alabama in mid-winter. I was unable to detect any difference myself, but all the American specimens which I took to the British Museum were observed by Mr. Doubleday to exhibit a slight peculiarity in the colouring of a minute part of the anterior wing,* a character first detected by Mr. T.F. Stephens, who has also discovered that similar slight, but equally constant variations, distinguish other Lepidoptera now inhabiting the opposite sides of the Atlantic, insects which, nevertheless, he and Mr. Westwood and the late Mr. Kirby, have always agreed to regard as mere varieties of the same species. (* Lyell's "Second Visit to the United States" volume 2 page 293.) Mr. T.V. Wollaston, in treating of the variation of insects in maritime situations and small islands, has shown how the colour, growth of the wings, and many other characters, undergo modification under the influence of local conditions, continued for long periods of time;* and Mr. Brown has lately called our attention to the fact that the insects of the Shetland Isles present slight deviations from the corresponding types occurring in Great Britain, but far less marked than those which distinguish the American from the European varieties.** In the case of Shetland, Mr. Brown remarks, a land communication may well be supposed to have prevailed with Scotland at a more modern era than that between Europe and America. In fact, we have seen that Shetland can hardly fail to have been united with Scotland after the commencement of the glacial period (see map, Figure 41); whereas a communication between the north of Europe by Iceland and Greenland (which, as before stated, once enjoyed a genial climate) must have been anterior to the glacial epoch. A much larger isolation, and the impossibility of varieties formed in the two separated areas crossing with each other, would account, according to Mr. Darwin's theory, for the much wider divergence observed in the specific types of the two regions. (* Wollaston, "On the Variation of Species" etc. London 1856.) (** "Transactions of Northern Entomological Society" 1862.) The reader will remember that at the commencement of the Glacial period there was scarcely any appreciable difference between the molluscous fauna and that now living. When therefore the events of the Glacial period, as described in the earlier part of this volume, are duly pondered on, and when we reflect that in the Upper Miocene period the living species of mollusca constitute only one-third of the whole fauna, we see clearly by how high a figure we must multiply the time in order to express the distance between the Miocene period and our own days. SPECIES OF MAMMALIA RECENT AND FOSSIL--PROBOSCIDIANS. But it may perhaps be said that the mammalia afford more conspicuous examples than do the mollusca, insects, or plants of the wide gaps which separate species and genera, and that if in this higher class such a multitude of transitional forms had ever existed as would be required to unite the Tertiary and Recent species into one series or net-work of allied or transitional forms, they could not so entirely have escaped observation whether in the fossil or living fauna. A zoologist who entertains such an opinion would do well to devote himself to the study of some one genus of mammalia, such as the elephant, rhinoceros, hippopotamus, bear, horse, ox, or deer; and after collecting all the materials he can get together respecting the extinct and Recent species, decide for himself whether the present state of science justifies his assuming that the chain could never have been continuous, the number of the missing links being so great. Among the extinct species formerly contemporary with man, no fossil quadruped has so often been alluded to in this work as the mammoth, Elephas primigenius. From a monograph on the proboscidians by Dr. Falconer, it appears that this species represents one extreme of a type of which the Pliocene Mastodon borsoni represents the other. Between these extremes there are already enumerated by Dr. Falconer no less than twenty-six species, some of them ranging as far back in time as the Miocene period, others still living, like the Indian and African forms. Two of these species, however, he has always considered as doubtful, Stegodon ganesa, probably a mere variety of one of the others, and Elephas priscus of Goldfuss, founded partly on specimens of the African elephant, assumed by mistake to be fossil, and partly on some aberrant forms of E. antiquus. The first effect of the intercalation of so many intermediate forms between the two most divergent types, has been to break down almost entirely the generic distinction between Mastodon and Elephas. Dr. Falconer, indeed, observes that Stegodon (one of several subgenera which he has founded) constitutes an intermediate group, from which the other species diverge through their dental characters, on the one side into the mastodons, and on the other into the Elephants.* (* "Quarterly Journal of the Geological Society" volume 13 1857 page 314.) The next result is to diminish the distance between the several members of each of these groups. Dr. Falconer has discovered that no less than four species of elephant were formerly confounded together under the title of Elephas primigenius, whence its supposed ubiquity in Pleistocene times, or its wide range over half the habitable globe. But even when this form has been thus restricted in its specific characters, it has still its geographical varieties; for the mammoth's teeth brought from America may in most instances, according to Dr. Falconer, be distinguished from those proper to Europe. On this American variety Dr. Leidy has conferred the name of E. americanus. Another race of the same mammoth (as determined by Dr. Falconer) existed, as we have seen, before the Glacial period, or at the time when the buried forest of Cromer and the Norfolk cliffs was deposited; and the Swiss geologists have lately found remains of the mammoth in their country, both in pre-glacial and post-glacial formations. Since the publication of Dr. Falconer's monograph, two other species of elephant, F. mirificus, Leidy, and F. imperator, have been obtained from the Pliocene formations of the Niobrara Valley in Nebraska, one of which, however, may possibly be found hereafter to be the same as E. columbi, Falc. A remarkable dwarf species also (Elephas melitensis) has been discovered, belonging, like the existing E. africanus, to the group Loxodon. This species has been established by Dr. Falconer on remains found by Captain Spratt R.N. in a cave in Malta.* (* "Proceedings of the Geological Society" London 1862.) How much the difficulty of discriminating between the fossil representatives of this genus may hereafter augment, when all the species with their respective geographical varieties are known, may be inferred from the following fact--Professor H. Schlegel, in a recently published memoir, endeavours to show that the living elephant of Sumatra agrees with that of Ceylon, but is a distinct species from that of Continental India, being distinguishable by the number of its dorsal vertebrae and ribs, the form of its teeth, and other characteristics.* (* Schlegel, "Natural History Review" Number 5 1862 page 72.) Dr. Falconer, on the other hand, considers these two living species as mere geographical varieties, the characters referred to not being constant, as he has ascertained, on comparing different individuals of E. indicus in different parts of Bengal in which the ribs vary from nineteen to twenty, and different varieties of E. africanus in which they vary from twenty to twenty-one. An inquiry into the various species of the genus Rhinoceros, recent and fossil, has led Dr. Falconer to analogous results, as might be inferred from what was said in Chapter 10, and as a forthcoming memoir by the same writer will soon more fully demonstrate. Among the fossils brought in 1858 by Mr. Hayden from the Niobrara Valley, Dr. Leidy describes a rhinoceros so like the Asiatic species, R. indicus, that he at first referred it to the same, and, what is most singular, he remarks generally of the Pliocene fauna of that part of North America that it is far more related in character to the Pleistocene and Recent fauna of Europe than to that now inhabiting the American continent. It seems indeed more and more evident that when we speculate in future on the pedigree of any extinct quadruped which abounds in the drift or caverns of Europe, we shall have to look to North and South America as a principal source of information. Thirty years ago, if we had been searching for fossil types which might fill up a gap between two species or genera of the horse tribe (or great family of the Solipedes), we might have thought it sufficient to have got together as ample materials as we could obtain from the continents of Europe, Africa, and Asia. We might have presumed that as no living representative of the equine family, whether horse, ass, zebra, or quagga, had been furnished by North or South America when those regions were first explored by Europeans, a search in the transatlantic world for fossil species might be dispensed with. But how different is the prospect now opening before us! Mr. Darwin first detected the remains of a fossil horse during his visit to South America, since which two other species have been met with on the same continent, while in North America, in the valley of the Nebraska alone, Mr. Hayden, besides a species not distinguishable from the domestic horse, has obtained, according to Dr. Leidy, representatives of five other fossil genera of Solipedes. These he names, Hipparion, Protohippus, Merychippus, Hypohippus, and Parahippus. On the whole, no less than twelve equine species, belonging to seven genera (including the Miocene Anchitherium of Nebraska), being already detected in the Tertiary and Post-Tertiary formations of the United States.* (* "Proceedings of the Academy of Natural Science" Philadelphia for 1858 page 89.) Professors Unger* and Heer** have advocated, on botanical grounds, the former existence of an Atlantic continent during some part of the Tertiary period, as affording the only plausible explanation that can be imagined, of the analogy between the Miocene flora of Central Europe and the existing flora of Eastern America. Professor Oliver, on the other hand, after showing how many of the American types found fossil in Europe are common to Japan, inclines to the theory, first advanced by Dr. Asa Gray, that the migration of species, to which the community of types in the eastern states of North America and the Miocene flora of Europe is due, took place when there was an overland communication from America to eastern Asia between the fiftieth and sixtieth parallels of latitude, or south of Behring Straits, following the direction of the Aleutian islands.*** By this course they may have made their way, at any epoch, Miocene, Pliocene, or Pleistocene, antecedently to the glacial epoch, to Mongolia, on the east coast of northern Asia. (* "Die versunkene Insel Atlantis.") (** "Flora tertiaria Helvetiae.") (*** Oliver, Lecture at the Royal Institution, March 7, 1862.) We have already seen that a large proportion of the living quadrupeds of Mongolia (34 out of 48) are specifically identical with those at present inhabiting the continent of Western Europe and the British Isles. A monograph on the hippopotamus, bear, ox, stag, or any other genus of mammalia common in the European drift or caverns, might equally well illustrate the defective state of the materials at present at our command. We are rarely in possession of one perfect skeleton of any extinct species, still less of skeletons of both sexes, and of different ages. We usually know nothing of the geographical varieties of the Pleistocene and Pliocene species, least of all, those successive changes of form which they must have undergone in the preglacial epoch between the Upper Miocene and Pleistocene eras. Such being the poverty of our palaeontological data, we cannot wonder that osteologists are at variance as to whether certain remains found in caverns are of the same species as those now living; whether, for example, the Talpa fossilis is really the common mole, the Meles morreni the common badger, Lutra antiqua the otter of Europe, Sciurus priscus the squirrel, Arctomys primigenia the marmot, Myoxus fossilis the dormouse, Schmerling's Felis engihoulensis the European lynx, or whether Ursus spelaeus and Ursus priscus are not extinct races of the living brown bear (Ursus arctos). If at some future period all the above-mentioned species should be united with their allied congeners, it cannot fail to enlarge our conception of the modifications which a species is capable of undergoing in the course of time, although the same form may appear absolutely immutable within the narrow range of our experience. LONGEVITY OF SPECIES IN THE MAMMALIA. In the "Principles of Geology," in 1833,* I stated that the longevity of species in the class mollusca exceeded that in the mammalia. It has been since found that this generalisation can be carried much farther, and that in fact the law which governs the changes in organic being is such that the lower their place in a graduated scale, or the simpler their structure, the more persistent are they in form and organisation. I soon became aware of the force of this rule in the class mollusca, when I first attempted to calculate the numerical proportion of Recent species in the Newer Pliocene formations as compared to the Older Pliocene, and of them again as contrasted with the Miocene; for it appeared invariably that a greater number of the lamellibranchs could be identified with living species than of the gasteropods, and of these last a greater number in the lower division, that of entire-mouthed univalves, than in that of the siphonated. In whatever manner the changes have been brought about, whether by variation and natural selection, or by any other causes, the rate of change has been greater where the grade of organisation is higher. (* 1st edition volume 3 pages 48 and 140.) It is only, therefore, where there is a full representation of all the principal orders of mollusca, or when we compare those of corresponding grade, that we can fully rely on the percentage test, or on the proportion of Recent to extinct species as indicating the relation of two groups to the existing fauna. The foraminifera which exemplify the lowest stage of animal existence exhibit, as we learn from the researches of Dr. Carpenter and of Messrs. Jones and Parker, extreme variability in their specific forms, and yet these same forms are persistent throughout vast periods of time, exceeding, in that respect, even the brachiopods before mentioned. Dr. Hooker observes, in regard to plants of complex floral structure, that they manifest their physical superiority in a greater extent of variation and in thus better securing a succession of race, an attribute which in some senses he regards as of a higher order than that indicated by mere complexity or specialisation of organ.* (* "Introductory Essay to the Flora of Australia" page 7.) As one of the consequences of this law, he says that species, genera, and orders are, on the whole, best limited in plants of higher grade, the dicotyledons better than the monocotyledons, and the Dichlamydeae better than the Achlamydeae. Mr. Darwin remarks, "We can, perhaps, understand the apparently quicker rate of change in terrestrial, and in more highly organised productions, compared with marine and lower productions, by the more complex relations of the higher beings to their organic and inorganic conditions of life."* (* "Origin of Species" 3rd edition page 340.) If we suppose the mammalia to be more sensitive than are the inferior classes of the vertebrata, to every fluctuation in the surrounding conditions, whether of the animate or inanimate world, it would follow that they would oftener be called upon to adapt themselves by variation to new conditions, or if unable to do so, to give place to other types. This would give rise to more frequent extinction of varieties, species, and genera, whereby the surviving types would be better limited, and the average duration of the same unaltered specific types would be lessened. ABSENCE OF MAMMALIA IN ISLANDS CONSIDERED IN REFERENCE TO TRANSMUTATION. But if mammalia vary upon the whole at a more rapid rate than animals lower in the scale of being, it must not be supposed that they can alter their habits and structures readily, or that they are convertible in short periods into new species. The extreme slowness with which such changes of habits and organisation take place, when new conditions arise, appears to be well exemplified by the absence even of small warm-blooded quadrupeds in islands far from continents, however well such islands may be fitted by their dimensions to support them. Mr. Darwin has pointed to this absence of mammalia as favouring his views, observing that bats, which are the only exceptions to the rule, might have made their way to distant islands by flight, for they are often met with on the wing far out at sea. Unquestionably, the total exclusion of quadrupeds in general, which could only reach such isolated habitations by swimming, seems to imply that nature does not dispense with the ordinary laws of reproduction when she peoples the earth with new forms; for if causes purely immaterial were alone at work, we might naturally look for squirrels, rabbits, polecats, and other small vegetable feeders and beasts of prey, as often as for bats, in the spots alluded to. On the other hand, I have found it difficult to reconcile the antiquity of certain islands, such as those of the Madeiran Archipelago, and those of still larger size in the Canaries, with the total absence of small indigenous quadrupeds, for, judging by ancient deposits of littoral shells, now raised high above the level of the sea, several of these volcanic islands (Porto Santo and the Grand Canary among others) must have existed ever since the Upper Miocene period. But, waiving all such claims to antiquity, it is at least certain that since the close of the Newer Pliocene period, Madeira, and Porto Santo have constituted two separate islands, each in sight of the other, and each inhabited by an assemblage of land shells (Helix, Pupa, Clausilia, etc.), for the most part different or proper to each island. About thirty-two fossil species have been obtained in Madeira, and forty-two in Porto Santo, only five of the whole being common to both islands. In each the living land-shells are equally distinct, and correspond, for the most part, with the species found fossil in each island respectively. Among the fossil species, one or two appear to be entirely extinct, and a larger number have disappeared from the fauna of the Madeiran Archipelago, though still extant in Africa and Europe. Many which were amongst the most common in the Pliocene period, have now become the scarcest, and others formerly scarce, are now most numerously represented. The variety-making force has been at work with such energy--perhaps we ought to say, has had so much time for its development--that almost every isolated rock within gun-shot of the shores has its peculiar living forms, or those very marked races to which Mr. Lowe, in his excellent description of the fauna, has given the name of "sub-species." Since the fossil shells were embedded in sand near the coast, these volcanic islands have undergone considerable alterations in size and shape by the wasting action of the waves of the Atlantic beating incessantly against the cliffs, so that the evidence of a vast lapse of time is derivable from inorganic as well as from organic phenomena. During this period no mammalia, not even of small species, excepting bats, have made their appearance, whether in Madeira and Porto-Santo or in the larger and more numerous islands of the Canarian group. It might have been expected, from some expressions met with here and there in the "Origin of Species," though not perhaps from a fair interpretation of the whole tenor of the author's reasoning, that this dearth of the highest class of vertebrata is inconsistent with the powers of mammalia to accommodate their habits and structures to new conditions. Why did not some of the bats, for example, after they had greatly multiplied, and were hard pressed by a scarcity of insects on the wing, betake themselves to the ground in search of prey, and, gradually losing their wings, become transformed into non-volant Insectivora? Mr. Darwin tells me that he has learnt that there is a bat in India which has been known occasionally to devour frogs. One might also be tempted to ask, how it has happened that the seals which swarmed on the shores of Madeira and the Canaries, before the European colonists arrived there, were never induced, when food was scarce in the sea, to venture inland from the shores, and begin in Teneriffe, and the Grand Canary especially, and other large islands, to acquire terrestrial habits, venturing first a few yards inland, and then farther and farther until they began to occupy some of the "places left vacant in the economy of nature." During these excursions, we might suppose some varieties, which had the skin of the webbed intervals of their toes less developed, to succeed best in walking on the land, and in the course of several generations they might exchange their present gait or manner of shuffling along and jumping by aid of the tail and their fin-like extremities, for feet better adapted for running. It is said that one of the bats in the island of Palma (one of the Canaries) is of a peculiar species, and that some of the Cheiroptera of the Pacific islands are even of peculiar genera. If so, we seem, on organic as well as on geological grounds, to be precluded from arguing that there has not been time for great divergence of character. We seem also entitled to ask why the bats and rodents of Australia, which are spread so widely among the marsupials over that continent, have never, under the influence of the principle of progression, been developed into higher placental types, since we have now ascertained that that continent was by no means unfitted to sustain such mammalia, for these when once introduced by Man have run wild and become naturalised in many parts. The following answers may perhaps be offered to the above criticisms of some of Mr. Darwin's theoretical views. First, as to the bats and seals: they are what zoologists call aberrant and highly specialised types, and therefore precisely those which might be expected to display a fixity and want of pliancy in their organisation, or the smallest possible aptitude for deviating in new directions towards new structures, and the acquisition of such altered habits as a change from aquatic to terrestrial or from Volant to non-volant modes of living would imply. Secondly, the same powers of flight which enabled the first bats to reach Madeira or the Canaries, would bring others from time to time from the African continent, which, mixing with the first emigrants and crossing with them, would check the formation of new races, or keep them true to the old types, as is found to be actually the case with the birds of Madeira and the Bermudas. This would happen the more surely, if, as Mr. Darwin has endeavoured to prove, the offspring of races slightly varying are usually more vigorous than the progeny of parents of the same race, and would be more prolific, therefore, than the insular stock which had been for a long time breeding in and in. The same cause would tend in a still more decided manner to prevent the seals from diverging into new races or "incipient species," because they range freely over the wide ocean, and, may therefore have continual intercourse with all other individuals of their species. Thirdly, as to peculiar species, and even genera of bats in islands, we are perhaps too little acquainted at present with all the species and genera of the neighbouring continents to be able to affirm, with any degree of confidence, that the forms supposed to be peculiar do not exist elsewhere: those of the Canaries in Africa, for example. But what is still more important, we must bear in mind how many species and genera of Pleistocene mammalia have everywhere become extinct by causes independent of Man. It is always possible, therefore, that some types of Cheiroptera, originally derived from the main land, have survived in islands, although they have gradually died out on the continents from whence they came; so that it would be rash to infer that there has been time for the creation, whether by variation or other agency, of new species or genera in the islands in question. As to the Rodents and Cheiroptera of Australia, we are as yet too ignorant of the Pleistocene and Pliocene fauna of that part of the world, to be able to decide whether the introduction of such forms dates from a remote geological time. We know, however, that, before the Recent period, that continent was peopled with large kangaroos, and other herbivorous and carnivorous marsupials, of species long since extinct, their remains having been discovered in ossiferous caverns. The preoccupancy of the country by such indigenous tribes may have checked the development of the placental Rodents and Cheiroptera, even were we to concede the possibility of such forms being convertible by variation and progressive development into higher grades of mammalia. IMPERFECTION OF THE GEOLOGICAL RECORD [42]. When treating in the eighth chapter of the dearth of human bones in alluvium containing flint implements in abundance, I pointed out that it is not part of the plan of Nature to write everywhere, and at all times, her autobiographical memoirs. On the contrary, her annals are local and exceptional from the first, and portions of them are afterwards ground into mud, sand, and pebbles, to furnish materials for new strata. Even of those ancient monuments now forming the crust of the earth, which have not been destroyed by rivers and the waves of the sea, or which have escaped being melted by volcanic heat, three-fourths lie submerged beneath the ocean, and are inaccessible to Man; while of those which form the dry land, a great part are hidden for ever from our observation by mountain masses, thousands of feet thick, piled over them. Mr. Darwin has truly said that the fossiliferous rocks known to geologists consist, for the most part, of such as were formed when the bottom of the sea was subsiding. This downward movement protects the new deposits from denudation, and allows them to accumulate to a great thickness; whereas sedimentary matter, thrown down where the sea-bottom is rising, must almost invariably be swept away by the waves as fast as the land emerges. When we reflect, therefore, on the fractional state of the annals which are handed down to us, and how little even these have as yet been studied, we may wonder that so many geologists should attribute every break in the series of strata and every gap in the past history of the organic world to catastrophes and convulsions of the earth's crust or to leaps made by the creational force from species to species, or from class to class. For it is clear that, even had the series of monuments been perfect and continuous at first (an hypothesis quite opposed to the analogy of the working of causes now in action), it could not fail to present itself to our eyes in a broken and disconnected state. Those geologists who have watched the progress of discovery during the last half century can best appreciate the extent to which we may still hope by future exertion to fill up some of the wider chasms which now interrupt the regular sequence of fossiliferous rocks. The determination, for example, of late years of the true place of the Hallstadt and St. Cassian beds on the north and south flanks of the Austrian Alps, has revealed to us, for the first time, the marine fauna of a period (that of the Upper Trias) of which, until lately, but little was known. In this case, the palaeontologist is called upon suddenly to intercalate about 800 species of Mollusca and Radiata, between the fauna of the Lower Lias and that of the Middle Trias. The period in question was previously believed, even by many a philosophical geologist, to have been comparatively barren of organic types. In England, France, and northern Germany, the only known strata of Upper Triassic date had consisted almost entirely of fresh or brackish-water beds, in which the bones of terrestrial and amphibious reptiles were the most characteristic fossils. The new fauna was, as might have been expected, in part peculiar, not a few of the species of Mollusca being referable to new genera; while some species were common to the older, and some to the newer rocks. On the whole, the new forms have helped greatly to lessen the discordance, not only between the Lias and Trias, but also generally between Palaeozoic and Mesozoic formations. Thus the genus Orthoceras has been for the first time recognised in a Mesozoic deposit, and with it we find associated, for the first time, large Ammonites with foliated lobes, a form never seen before below the Lias; also the Ceratites, a family of Cephalopods never before met with in the Upper Trias, and never before in the same stratum with such lobed Ammonites. We can now no longer doubt that should we hereafter have an opportunity of studying an equally rich marine fauna of the age of the Lower Trias (or Bunter Sandstein), the marked hiatus which still separates the Triassic and Permian eras would almost disappear. Archaeopteryx macrurus, Owen. I could readily add a copious list of minor deposits, belonging to the Primary, Secondary and Tertiary series, which we have been called upon in like manner to intercalate in the course of the last quarter of a century into the chronological series previously known; but it would lead me into too long a digression. I shall therefore content myself with pointing out that it is not simply new formations which are brought to light from year to year, reminding us of the elementary state of our knowledge of palaeontology, but new types also of structure are discovered in rocks whose fossil contents were supposed to be peculiarly well known. The last and most striking of these novelties is "the feathered fossil" from the lithographic stone of Solenhofen. Until the year 1858, no well-determined skeleton of a bird had been detected in any rocks older than the Tertiary. In that year, Mr. Lucas Barrett found in the Cambridge Greensand of the Cretaceous series, the femur, tibia, and some other bones of a swimming bird, supposed by him to be of the gull tribe. His opinion as to the ornithic character of the remains was afterwards confirmed by Professor Owen. The Archaeopteryx macrurus, Owen, recently acquired by the British Museum, affords a second example of the discovery of the osseous remains of a bird in strata older than the Eocene. It was found in the great quarries of lithographic limestone at Solenhofen in Bavaria, the rock being a member of the Upper Oolite. It was at first conjectured in Germany, before any experienced osteologist had had an opportunity of inspecting the original specimen, that this fossil might be a feathered Pterodactyl (flying reptiles having been often met with in the same stratum), or that it might at least supply some connecting links between a reptile and a bird. But Professor Owen, in a memoir lately read to the Royal Society (November 20, 1862), has shown that it is unequivocally a bird, and that such of its characters as are abnormal are by no means strikingly reptilian. The skeleton was lying on its back when embedded in calcareous sediment, so that the ventral part is exposed to view. It is about 1 foot 8 inches long, and 1 foot across, from the apex of the right to that of the left wing. The furculum, or merry-thought, which is entire, marks the fore part of the trunk; the ischium, scapula, and most of the wing and leg bones are preserved, and there are impressions of the quill feathers and of down on the body. The vanes and shafts of the feathers can be seen by the naked eye. Fourteen long quill feathers diverge on each side of the metacarpal and phalangial bones, and decrease in length from 6 inches to 1 inch. The wings have a general resemblance to those of gallinaceous birds. The tarso-metatarsal, or drumstick, exhibits at its distal end a trifid articular surface supporting three toes, as in birds. The furculum, pelvis, and bones of the tail are in their natural position. The tail consists of twenty vertebrae, each of which supports a pair of plumes. The length of the tail with its feathers is 11 1/2 inches, and its breadth 3 1/2. It is obtusely truncated at the end. In all living birds the tail-feathers are arranged in fan-shaped order and attached to a coccygean bone, consisting of several vertebrae united together, whereas in the embryo state these same vertebrae are distinct. The greatest number is seen in the ostrich, which has eighteen caudal vertebrae in the foetal state, which are reduced to nine in the adult bird, many of them having been anchylosed together. Professor Owen therefore considers the tail of the Archaeopteryx as exemplifying the persistency of what is now an embryonic character. The tail, he remarks, is essentially a variable organ; there are long-tailed bats and short-tailed bats, long-tailed rodents and short-tailed rodents, long-tailed pterodactyls and short-tailed pterodactyls. The Archaeopteryx differs from all known birds, not only in the structure of its tail, but in having two, if not three, digits in the hand; but there is no trace of the fifth digit of the winged reptile. The conditions under which the skeleton occurs are such, says Professor Owen, as to remind us of the carcass of a gull which has been a prey to some Carnivore, which had removed all the soft parts, and perhaps the head, nothing being left but the bony legs and the indigestible quill-feathers. But since Professor Owen's paper was read, Mr. John Evans, whom I have often had occasion to mention in the earlier chapters of this work, seems to have found what may indicate a part of the missing cranium. He has called our attention to a smooth protuberance on the otherwise even surface of the slab of limestone which seems to be the cast of the brain or interior of the skull. Some part even of the cranial bone itself appears to be still buried in the matrix. Mr. Evans has pointed out the resemblance of this cast to one taken by himself from the cranium of a crow, and still more to that of a jay, observing that in the fossil the median line which separates the two hemispheres of the brain is visible. To conclude, we may learn from this valuable relic how rashly the existence of Birds at the epoch of the Secondary rocks has been questioned, simply on negative evidence, and secondly, how many new forms may be expected to be brought to light in strata with which we are already best acquainted, to say nothing of the new formations which geologists are continually discovering. CHAPTER 23. -- ORIGIN AND DEVELOPMENT OF LANGUAGES AND SPECIES COMPARED [43]. Aryan Hypothesis and Controversy. The Races of Mankind change more slowly than their Languages. Theory of the gradual Origin of Languages. Difficulty of defining what is meant by a Language as distinct from a Dialect. Great Number of extinct and living Tongues. No European Language a Thousand Years old. Gaps between Languages, how caused. Imperfection of the Record. Changes always in Progress. Struggle for Existence between rival Terms and Dialects. Causes of Selection. Each Language formed slowly in a single Geographical Area. May die out gradually or suddenly. Once lost can never be revived. Mode of Origin of Languages and Species a Mystery. Speculations as to the Number of original Languages or Species unprofitable. The supposed existence, at a remote and unknown period, of a language conventionally called the Aryan, has of late years been a favourite subject of speculation among German philologists, and Professor Max Muller has given us lately the most improved version of this theory, and has set forth the various facts and arguments by which it may be defended, with his usual perspicuity and eloquence. He observes that if we know nothing of the existence of Latin--if all historical documents previous to the fifteenth century had been lost--if tradition even was silent as to the former existence of a Roman empire, a mere comparison of the Italian, Spanish, Portuguese, French, Wallachian, and Rhaetian dialects would enable us to say that at some time there must have been a language from which these six modern dialects derive their origin in common. Without this supposition it would be impossible to account for their structure and composition, as, for example, for the forms of the auxiliary verb "to be," all evidently varieties of one common type, while it is equally clear that no one of the six affords the original form from which the others could have been borrowed. So also in none of the six languages do we find the elements of which these verbal and other forms could have been composed; they must have been handed down as relics from a former period, they must have existed in some antecedent language, which we know to have been the Latin. But, in like manner, he goes on to show, that Latin itself, as well as Greek, Sanscrit, Zend (or Bactrian), Lithuanian, old Sclavonic, Gothic, and Armenian are also eight varieties of one common and more ancient type, and no one of them could have been the original from which the others were borrowed. They have all such an amount of mutual resemblance as to point to a more ancient language, the Aryan, which was to them what Latin was to the six Romance languages. The people who spoke this unknown parent speech, of which so many other ancient tongues were off-shoots, must have migrated at a remote era to widely separated regions of the old world, such as Northern Asia, Europe, and India south of the Himalaya.* (* Max Muller, "Comparative Mythology" Oxford Essays 1856.) The soundness of some parts of this Aryan hypothesis has lately been called in question by Mr. Crawfurd, on the ground that the Hindoos, Persians, Turks, Scandinavians, and other people referred to as having derived not only words but grammatical forms from an Aryan source, belong each of them to a distinct race, and all these races have, it is said, preserved their peculiar characters unaltered from the earliest dawn of history and tradition. If, therefore, no appreciable change has occurred in three or four thousand years, we should be obliged to assume a far more remote date for the first branching off of such races from a common stock than the supposed period of the Aryan migrations, and the dispersion of that language over many and distant countries. But Mr. Crawfurd has, I think, himself helped us to remove this stumbling-block, by admitting that a nation speaking a language allied to the Sanscrit (the oldest of the eight tongues alluded to), once probably inhabited that region situated to the north-west of India, which within the period of authentic history has poured out its conquering hordes over a great extent of Western Asia and Eastern Europe. The same people, he says, may have acted the same part in the long, dark night which preceded the dawn of tradition.* (* Crawfurd, "Transactions of the Ethnological Society" volume 1 1861.) These conquerors may have been few in number when compared to the populations which they subdued. In such cases the new settlers, although reckoned by tens of thousands, might merge in a few centuries into the millions of subjects which they ruled. It is an acknowledged fact that the colour and features of the Negro or European are entirely lost in the fourth generation, provided that no fresh infusion of one or other of the two races takes place. The distinctive physical features, therefore, of the Aryan conquerors might soon wear out and be lost in those of the nations they overran; yet many of the words, and, what is more in point, some of the grammatical forms of their language, might be retained by the masses which they had governed for centuries, these masses continuing to preserve the same features of race which had distinguished them long before the Aryan invasions. There can be no question that if we could trace back any set of cognate languages now existing to some common point of departure, they would converge and meet sooner in some era of the past than would the existing races of mankind; in other words, races change much more slowly than languages. But, according to the doctrine of transmutation, to form a new species would take an incomparably longer period than to form a new race. No language seems ever to last for a thousand years, whereas many a species seems to have endured for hundreds of thousands. A philologist, therefore, who is contending that all living languages are derivative and not primordial, has a great advantage over a naturalist who is endeavouring to inculcate a similar theory in regard to species. It may not be uninstructive, in order fairly to appreciate the vast difficulty of the task of those who advocate transmutation in natural history, to consider how hard it would be even for a philologist to succeed, if he should try to convince an assemblage of intelligent but illiterate persons that the language spoken by them, and all those talked by contemporary nations, were modern inventions, moreover that these same forms of speech were still constantly undergoing change, and none of them destined to last for ever. We will suppose him to begin by stating his conviction, that the living languages have been gradually derived from others now extinct, and spoken by nations which had immediately preceded them in the order of time, and that those again had used forms of speech derived from still older ones. They might naturally exclaim, "How strange it is that you should find records of a multitude of dead languages, that a part of the human economy which in our own time is so remarkable for its stability, should have been so inconstant in bygone ages! We all speak as our parents and grandparents spoke before us, and so, we are told, do the Germans and French. What evidence is there of such incessant variation in remoter times? and, if it be true, why not imagine that when one form of speech was lost, another was suddenly and supernaturally created by a gift of tongues or confusion of languages, as at the building of the Tower of Babel? Where are the memorials of all the intermediate dialects, which must have existed, if this doctrine of perpetual fluctuation be true? And how comes it that the tongues now spoken do not pass by insensible gradations the one into the other, and into the dead languages of dates immediately antecedent? "Lastly, if this theory of indefinite modifiability be sound, what meaning can be attached to the term language, and what definition can be given of it so as to distinguish a language from a dialect?" In reply to this last question, the philologist might confess that the learned are not agreed as to what constitutes a language as distinct from a dialect. Some believe that there are 4000 living languages, others that there are 6000, so that the mode of defining them is clearly a mere matter of opinion. Some contend, for example, that the Danish, Norwegian, and Swedish form one Scandinavian tongue, others that they constitute three different languages, others that the Danish and Norwegian are one--mere dialects of the same language, but that Swedish is distinct. The philologist, however, might fairly argue that this very ambiguity was greatly in favour of his doctrine, since if languages had all been constantly undergoing transmutation, there ought often to be a want of real lines of demarcation between them. He might, however, propose that he and his pupils should come to an understanding that two languages should be regarded as distinct whenever the speakers of them are unable to converse together, or freely to exchange ideas, whether by word or writing. Scientifically speaking, such a test might be vague and unsatisfactory, like the test of species by their capability of producing fertile hybrids; but if the pupil is persuaded that there are such things in nature as distinct languages, whatever may have been their origin, the definition above suggested might be of practical use, and enable the teacher to proceed with his argument. He might begin by undertaking to prove that none of the languages of modern Europe were a thousand years old. No English scholar, he might say, who has not specially given himself up to the study of Anglo-Saxon, can interpret the documents in which the chronicles and laws of England were written in the days of King Alfred, so that we may be sure that none of the English of the nineteenth century could converse with the subjects of that monarch if these last could now be restored to life. The difficulties encountered would not arise merely from the intrusion of French terms, in consequence of the Norman conquest, because that large portion of our language (including the articles, pronouns, etc.), which is Saxon has also undergone great transformations by abbreviation, new modes of pronunciation, spelling, and various corruptions, so as to be unlike both ancient and modern German. They who now speak German, if brought into contact with their Teutonic ancestors of the ninth century, would be quite unable to converse with them, and, in like manner, the subjects of Charlemagne could not have exchanged ideas with the Goths of Alaric's army, or with the soldiers of Arminius in the days of Augustus Caesar. So rapid indeed has been the change in Germany, that the epic poem called the Nibelungen Lied, once so popular, and only seven centuries old, cannot now be enjoyed, except by the erudite. If we then turn to France, we meet again with similar evidence of ceaseless change. There is a treaty of peace still extant a thousand years old, between Charles the Bald and King Louis of Germany (dated A.D. 841), in which the German king takes an oath in what was the French tongue of that day, while the French king swears in the German of the same era, and neither of these oaths would now convey a distinct meaning to any but the learned in these two countries. So also in Italy, the modern Italian cannot be traced back much beyond the time of Dante, or some six centuries before our time. Even in Rome, where there had been no permanent intrusion of foreigners, such as the Lombard settlers of German origin in the plains of the Po, the common people of the year 1000 spoke quite a distinct language from that of their Roman ancestors or their Italian descendants, as is shown by the celebrated chronicle of the monk Benedict, of the convent of St. Andrea on Mount Soracte, written in such barbarous Latin, and with such strange grammatical forms, that it requires a profoundly skilled linguist to decipher it.* (* See G. Pertz, "Monumenta Germanica" volume 3.) Having thus established the preliminary fact, that none of the tongues now spoken were in existence ten centuries ago, and that the ancient languages have passed through many a transitional dialect before they settled into the forms now in use, the philologist might bring forward proofs of the great numbers both of lost and living forms of speech. Strabo tells us that in his time, in the Caucasus alone (a chain of mountains not longer than the Alps, and much narrower), there were spoken at least seventy languages. At the present period the number, it is said, would be still greater if all the distinct dialects of those mountains were reckoned. Several of these Caucasian tongues admit of no comparison with any known living or lost Asiatic or European language. Others which are not peculiar are obsolete forms of known languages, such as the Georgian, Mongolian, Persian, Arabic, and Tartarian. It seems that as often as conquering hordes swept over that part of Asia, always coming from the north and east, they drove before them the inhabitants of the plains, who took refuge in some of the retired valleys and high mountain fastnesses, where they maintained their independence, as do the Circassians in our time in spite of the power of Russia. In the Himalayan Mountains, from Assam to its extreme north-western limit, and generally in the more hilly parts of British India, the diversity of languages is surprisingly great, impeding the advance of civilisation and the labours of the missionary. In South America and Mexico, Alexander Humboldt reckoned the distinct tongues by hundreds, and those of Africa are said to be equally numerous. Even in China, some eighteen provincial dialects prevail, almost all deviating so much from others that the speakers are not mutually intelligible, and besides these there are other distinct forms of speech in the mountains of the same empire. The philologist might next proceed to point out that the geographical relations of living and dead languages favour the hypothesis of the living ones having been derived from the extinct, in spite of our inability, in most instances, to adduce documentary evidence of the fact or to discover monuments of all the intermediate and transitional dialects which must have existed. Thus he would observe that the modern Romance languages are spoken exactly where the ancient Romans once lived or ruled, and the Greek of our days where the older classical Greek was formerly spoken. Exceptions to this rule might be detected, but they would be explicable by reference to colonisation and conquest. As to the many and wide gaps sometimes encountered between the dead and living languages, we must remember that it is not part of the plan of any people to preserve memorials of their forms of speech expressly for the edification of posterity. Their manuscripts and inscriptions serve some present purpose, are occasional and imperfect from the first, and are rendered more fragmentary in the course of time, some being intentionally destroyed, others lost by the decay of the perishable materials on which they are written; so that to question the theory of all known languages being derivative on the ground that we can rarely trace a passage from the ancient to the modern through all the dialects which must have flourished one after the other in the intermediate ages, implies a want of reflection on the laws which govern the recording as well as the obliterating processes. But another important question still remains to be considered, namely, whether the trifling changes which can alone be witnessed by a single generation, can possibly represent the working of that machinery which, in the course of many centuries, has given rise to such mighty revolutions in the forms of speech throughout the world. Everyone may have noticed in his own lifetime the stealing in of some slight alterations of accent, pronunciation or spelling, or the introduction of some words borrowed from a foreign language to express ideas of which no native term precisely conveyed the import. He may also remember hearing for the first time some cant terms or slang phrases, which have since forced their way into common use, in spite of the efforts of the purist. But he may still contend that "within the range of his experience," his language has continued unchanged, and he may believe in its immutability in spite of minor variations. The real question, however, at issue is, whether there are any limits to this variability. He will find on farther investigation, that new technical terms are coined almost daily in various arts, sciences, professions, and trades, that new names must be found for new inventions, that many of these acquire a metaphorical sense, and then make their way into general circulation, as "stereotyped," for instance, which would have been as meaningless to the men of the seventeenth century as would the new terms and images derived from steamboat and railway travelling to the men of the eighteenth. If the numerous words, idioms, and phrases, many of them of ephemeral duration, which are thus invented by the young and old in various classes of society, in the nursery, the school, the camp, the fleet, the courts of law and the study of the man of science or literature, could all be collected together and put on record, their number in one or two centuries might compare with the entire permanent vocabulary of the language. It becomes, therefore, a curious subject of inquiry, what are the laws which govern not only the invention, but also the "selection" of some of these words or idioms, giving them currency in preference to others?--for as the powers of the human memory are limited, a check must be found to the endless increase and multiplication of terms, and old words must be dropped nearly as fast as new ones are put into circulation. Sometimes the new word or phrase, or a modification of the old ones, will entirely supplant the more ancient expressions, or, instead of the latter being discarded, both may flourish together, the older one having a more restricted use. Although the speakers may be unconscious that any great fluctuation is going on in their language--although when we observe the manner in which new words and phrases are thrown out, as if at random or in sport, while others get into vogue, we may think the process of change to be the result of mere chance--there are nevertheless fixed laws in action, by which, in the general struggle for existence, some terms and dialects gain the victory over others. The slightest advantage attached to some new mode of pronouncing or spelling, from considerations of brevity or euphony, may turn the scale, or more powerful causes of selection may decide which of two or more rivals shall triumph and which succumb. Among these are fashion, or the influence of an aristocracy, whether of birth or education, popular writers, orators, preachers--a centralised government organising its schools expressly to promote uniformity of diction, and to get the better of provincialisms and local dialects. Between these dialects, which may be regarded as so many "incipient languages," the competition is always keenest when they are most nearly allied, and the extinction of any one of them destroys some of the links by which a dominant tongue may have been previously connected with some other widely distinct one. It is by the perpetual loss of such intermediate forms of speech that the great dissimilarity of the languages which survive is brought about. Thus, if Dutch should become a dead language, English and German would be separated by a wider gap. Some languages which are spoken by millions, and spread over a wide area, will endure much longer than others which have never had a wide range, especially if the tendency to incessant change in one of these dominant tongues is arrested for a time by a standard literature. But even this source of stability is insecure, for popular writers themselves are great innovators, sometimes coining new words, and still oftener new expressions and idioms, to embody their own original conceptions and sentiments, or some peculiar modes of thought and feeling characteristic of their age. Even when a language is regarded with superstitious veneration as the vehicle of divine truths and religious precepts, and which has prevailed for many generations, it will be incapable of permanently maintaining its ground. Hebrew had ceased to be a living language before the Christian era. Sanscrit, the sacred language of the Hindoos, shared the same fate, in spite of the veneration in which the Vedas are still held, and in spite of many a Sanscrit poem once popular and national. The Christians of Constantinople and the Morea still hear the New Testament and their liturgy read in ancient Greek, while they speak a dialect in which Paul might have preached in vain at Athens. So in the Catholic Church, the Italians pray in one tongue and talk another. Luther's translation of the Bible acted as a powerful cause of "selection," giving at once to one of many competing dialects (that of Saxony) a prominent and dominant position in Germany; but the style of Luther has, like that of our English Bible, already become somewhat antiquated. If the doctrine of gradual transmutation be applicable to languages, all those spoken in historical times must each of them have had a closely allied prototype; and accordingly, whenever we can thoroughly investigate their history, we find in them some internal evidence of successive additions by the invention of new words or the modification of old ones. Proofs also of borrowing are discernible, letters being retained in the spelling of some words which have no longer any meaning as they are now pronounced--no connection with any corresponding sounds. Such redundant or silent letters, once useful in the parent speech, have been aptly compared by Mr. Darwin to rudimentary organs in living beings, which, as he interprets them, have at some former period been more fully developed, having had their proper functions to perform in the organisation of a remote progenitor. If all known languages are derivative and not primordial creations, they must each of them have been slowly elaborated in a single geographical area. No one of them can have had two birthplaces. If one were carried by a colony to a distant region, it would immediately begin to vary unless frequent intercourse was kept up with the mother country. The descendants of the same stock, if perfectly isolated, would in five or six centuries, perhaps sooner, be quite unable to converse with those who remained at home, or with those who may have migrated to some distant region, where they were shut out from all communication with others speaking the same tongue. A Norwegian colony which settled in Iceland in the ninth century, maintained its independence for about 400 years, during which time the old Gothic which they at first spoke became corrupted and considerably modified. In the meantime the natives of Norway, who had enjoyed much commercial intercourse with the rest of Europe, acquired quite a new speech, and looked on the Icelandic as having been stationary, and as representing the pure Gothic original of which their own was an offshoot. A German colony in Pennsylvania was cut off from frequent communication with Europe for about a quarter of a century, during the wars of the French Revolution between 1792 and 1815. So marked had been the effect even of this brief and imperfect isolation, that when Prince Bernhard of Saxe-Weimar travelled among them a few years after the peace, he found the peasants speaking as they had done in Germany in the preceding century,*) and retaining a dialect which at home had already become obsolete. (* "Travels of Prince Bernhard of Saxe-Weimar, in North America, in 1825 and 1826", page 123.) Even after the renewal of the German emigration from Europe, when I travelled in 1841 among the same people in the retired valleys of the Alleghenies, I found the newspapers full of terms half English and half German, and many an Anglo-Saxon word, which had assumed a Teutonic dress, as "fencen," to fence, instead of umzaunen, "flauer" for flour, instead of mehl, and so on. What with the retention of terms no longer in use in the mother country, and the borrowing of new ones from neighbouring states, there might have arisen in Pennsylvania in five or six generations, but for the influx of newcomers from Germany, a mongrel speech equally unintelligible to the Anglo-Saxon and to the inhabitants of the European fatherland. If languages resemble species in having had each their "specific centre" or single area of creation, in which they have been slowly formed, so each of them is alike liable to slow or to sudden extinction. They may die out very gradually in consequence of transmutation, or abruptly by the extermination of the last surviving representatives of the unaltered type. We know in what century the last Dodo perished, and we know that in the seventeenth century the language of the Red Indians of Massachusetts, into which Father Eliot had translated the Bible, and in which Christianity was preached for several generations, ceased to exist, the last individuals by whom it was spoken having at that period died without issue.* (* Lyell, "Travels in North America" volume 1 page 260 1845.) But if just before that event the white man had retreated from the continent, or had been swept off by an epidemic, those Indians might soon have repeopled the wilderness, and their copious vocabulary and peculiar forms of expression might have lasted without important modification to this day. The extinction, however, of languages in general is not abrupt, any more than that of species. It will also be evident from what has been said, that a language which has once died out can never be revived, since the same assemblage of conditions can never be restored even among the descendants of the same stock, much less simultaneously among all the rounding nations with whom they may be in contact. We may compare the persistency of languages, or the tendency of each generation to adopt without change the vocabulary of its predecessor, to the force of inheritance in the organic world, which causes the offspring to resemble its parents. The inventive power which coins new words or modifies old ones, and adapts them to new wants and conditions as often as these arise, answers to the variety-making power in the animate creation. Progressive improvement in language is a necessary consequence of the progress of the human mind from one generation to another. As civilisation advances, a greater number of terms are required to express abstract ideas, and words previously used in a vague sense, so long as the state of society was rude and barbarous, gradually acquire more precise and definite meanings, in consequence of which several terms must be employed to express ideas and things, which a single word had before signified, though somewhat loosely and imperfectly. The farther this subdivision of function is carried, the more complete and perfect the language becomes, just as species of higher grade have special organs, such as eyes, lungs, and stomach, for seeing, breathing, and digesting, which in simple organisms are all performed by one and the same part of the body.* (* See Herbert Spencer's "Psychology" and "Scientific Essays.") When we had satisfied ourselves that all the existing languages, instead of being primordial creations, or the direct gifts of a supernatural Power, have been slowly elaborated, partly by the modification of pre-existing dialects, partly by borrowing terms at successive periods from numerous foreign sources, and partly by new inventions made some of them deliberately, and some casually and as it were fortuitously--when we have discovered the principal causes of selection, which have guided the adoption or rejection of rival names for the same things and ideas, rival modes of pronouncing the same words and provincial dialects competing one with another--we are still very far from comprehending all the laws which have governed the formation of each language. It was a profound saying of William Humboldt, that "Man is Man only by means of speech, but in order to invent speech he must be already Man." Other animals may be able to utter sounds more articulate and as varied as the click of the Bushman, but voice alone can never enable brute intelligence to acquire language. When we consider the complexity of every form of speech spoken by a highly civilised nation, and discover that the grammatical rules and the inflections which denote number, time, and equality are usually the product of a rude state of society--that the savage and the sage, the peasant and man of letters, the child and the philosopher, have worked together, in the course of many generations, to build up a fabric which has been truly described as a wonderful instrument of thought, a machine, the several parts of which are so well adjusted to each other as to resemble the product of one period and of a single mind--we cannot but look upon the result as a profound mystery, and one of which the separate builders have been almost as unconscious as are the bees in a hive of the architectural skill and mathematical knowledge which is displayed in the construction of the honeycomb. In our attempts to account for the origin of species, we find ourselves still sooner brought face to face with the working of a law of development of so high an order as to stand nearly in the same relation as the Deity himself to man's finite understanding, a law capable of adding new and powerful causes, such as the moral and intellectual faculties of the human race, to a system of nature which had gone on for millions of years without the intervention of any analogous cause. If we confound "Variation" or "Natural Selection" with such creational laws, we deify secondary causes or immeasurably exaggerate their influence. Yet we ought by no means to undervalue the importance of the step which will have been made, should it hereafter become the generally received opinion of men of science (as I fully expect it will), that the past changes of the organic world have been brought about by the subordinate agency of such causes as "Variation" and "Natural Selection." All our advances in the knowledge of Nature have consisted of such steps as these, and we must not be discouraged because greater mysteries remain behind wholly inscrutable to us. If the philologist is asked whether in the beginning of things there was one or five, or a greater number of languages, he may answer that, before he can reply to such a question, it must be decided whether the origin of Man was single, or whether there were many primordial races. But he may also observe, that if mankind began their career in a rude state of society, their whole vocabulary would be limited to a few words, and that if they then separated into several isolated communities, each of these would soon acquire an entirely distinct language, some roots being lost and others corrupted and transformed beyond the possibility of subsequent identification, so that it might be hopeless to expect to trace back the living and dead languages to one starting point, even if that point were of much more modern date than we have now good reason to suppose. In like manner it may be said of species, that if those first formed were of very simple structure, and they began to vary and to lose some organs by disuse and acquire new ones by development, they might soon differ as much as so many distinctly created primordial types. It would therefore be a waste of time to speculate on the number of original monads or germs from which all plants and animals were subsequently evolved, more especially as the oldest fossiliferous strata known to us may be the last of a long series of antecedent formations, which once contained organic remains. It was not till geologists ceased to discuss the condition of the original nucleus of the planet, whether it was solid or fluid, and whether it owed its fluidity to aqueous or igneous causes, that they began to achieve their great triumphs; and the vast progress which has recently been made in showing how the living species may be connected with the extinct by a common bond of descent, has been due to a more careful study of the actual state of the living world, and to those monuments of the past in which the relics of the animate creation of former ages are best preserved and least mutilated by the hand of time. CHAPTER 24. -- BEARING OF THE DOCTRINE OF TRANSMUTATION ON THE ORIGIN OF MAN, AND HIS PLACE IN THE CREATION. Whether Man can be regarded as an Exception to the Rule if the Doctrine of Transmutation be embraced for the rest of the Animal Kingdom. Zoological Relations of Man to other Mammalia. Systems of Classification. Term Quadrumanous, why deceptive. Whether the Structure of the Human Brain entitles Man to form a distinct Sub-class of the Mammalia. Intelligence of the lower Animals compared to the Intellect and Reason of Man. Grounds on which Man has been referred to a distinct Kingdom of Nature. Immaterial Principle common to Man and Animals. Non-discovery of intermediate Links among Fossil Anthropomorphous Species. Hallam on the compound Nature of Man, and his Place in the Creation. Great Inequality of mental Endowment in different Human Races and Individuals developed by Variation and ordinary Generation. How far a corresponding Divergence in physical Structure may result from the Working of the same Causes. Concluding remarks. Some of the opponents of transmutation, who are well versed in Natural History, admit that though that doctrine is untenable, it is not without its practical advantages as a "useful working hypothesis," often suggesting good experiments and observations and aiding us to retain in the memory a multitude of facts respecting the geographical distribution of genera and species, both of animals and plants, the succession in time of organic remains, and many other phenomena which, but for such a theory, would be wholly without a common bond of relationship. It is in fact conceded by many eminent zoologists and botanists, as before explained, that whatever may be the nature of the species-making power or law, its effects are of such a character as to imitate the results which variation, guided by natural selection, would produce, if only we could assume with certainty that there are no limits to the variability of species. But as the anti-transmutationists are persuaded that such limits do exist, they regard the hypothesis as simply a provisional one, and expect that it will one day be superseded by another cognate theory, which will not require us to assume the former continuousness of the links which have connected the past and present states of the organic world, or the outgoing with the incoming species. In like manner, many of those who hesitate to give in their full adhesion to the doctrine of progression, the other twin branch of the development theory, and who even object to it, as frequently tending to retard the reception of new facts supposed to militate against opinions solely founded on negative evidence, are nevertheless agreed that on the whole it is of great service in guiding our speculations. Indeed it cannot be denied that a theory which establishes a connection between the absence of all relics of vertebrata in the oldest fossiliferous rocks, and the presence of man's remains in the newest, which affords a more than plausible explanation of the successive appearance in strata of intermediate age of the fish, reptile, bird, and mammal, has no ordinary claims to our favour as comprehending the largest number of positive and negative facts gathered from all parts of the globe, and extending over countless ages, that science has perhaps ever attempted to embrace in one grand generalisation. But will not transmutation, if adopted, require us to include the human race in the same continuous series of developments, so that we must hold that Man himself has been derived by an unbroken line of descent from some one of the inferior animals? We certainly cannot escape from such a conclusion without abandoning many of the weightiest arguments which have been urged in support of variation and natural selection considered as the subordinate causes by which new types have been gradually introduced into the earth. Many of the gaps which separate the most nearly allied genera and orders of mammalia are, in a physical point of view, as wide as those which divide Man from the mammalia most nearly akin to him, and the extent of his isolation, whether we regard his whole nature or simply his corporeal attributes, must be considered before we can discuss the bearing of transmutation upon his origin and place in the creation. SYSTEMS OF CLASSIFICATION. In order to qualify ourselves to judge of the degree of affinity in physical organisation between Man and the lower animals, we cannot do better than study those systems of classification which have been proposed by the most eminent teachers of natural history. Of these an elaborate and faithful summary has recently been drawn up by the late Isidore Geoffroy St. Hilaire, which the reader will do well to consult.* (* "Histoire Naturale Generale des Regnes organiques" Paris volume 2 1856.) He begins by passing in review numerous schemes of classification, each of them having some merit, and most of them having been invented with a view of assigning to Man a separate place in the system of Nature, as, for example, by dividing animals into rational and irrational, or the whole organic world into three kingdoms, the human, the animal, and the vegetable--an arrangement defended on the ground that Man is raised as much by his intelligence above the animals as are these by their sensibility above plants. Admitting that these schemes are not unphilosophical, as duly recognising the double nature of Man (his moral and intellectual, as well as his physical attributes), Isidore G. St. Hilaire observes that little knowledge has been imparted by them. We have gained, he says, much more from those masters of the science who have not attempted any compromise between two distinct orders of ideas, the physical and psychological, and who have confined their attention strictly to Man's physical relation to the lower animals. Linnaeus led the way in this field of inquiry by comparing Man and the apes, in the same manner as he compared these last with the carnivores, ruminants, rodents, or any other division of warm-blooded quadrupeds. After several modifications of his original scheme, he ended by placing Man as one of the many genera in his order Primates, which embraced not only the apes and lemurs, but the bats also, as he found these last to be nearly allied to some of the lowest forms of the monkeys. But all modern naturalists, who retain the order Primates, agree to exclude from it the bats or Cheiroptera; and most of them class Man as one of several families of the order Primates. In this, as in most systems of classification, the families of modern zoologists and botanists correspond with the genera of Linnaeus. Blumenbach, in 1779, proposed to deviate from this course, and to separate Man from the apes as an order apart, under the name of Bimana, or two-handed. In making this innovation he seems at first to have felt that it could not be justified without calling in psychological considerations to his aid, to strengthen those which were purely anatomical; for, in the earliest edition of his "Manual of Natural History," he defined Man to be "animal rationale, loquens, erectum, bimanum," whereas in later editions he restricted himself entirely to the two last characters, namely, the erect position and the two hands, or "animal erectum, bimanum." The terms "bimanous" and "quadrumanous" had been already employed by Buffon in 1766, but not applied in a strict zoological classification till so used by Blumenbach. Twelve years later, Cuvier adopted the same order Bimana for the human family, while the apes, monkeys, and lemurs constituted a separate order called Quadrumana. Respecting this last innovation, Isidore G. St. Hilaire asks, "How could such a division stand, repudiated as it was by the anthropologists in the name of the moral and intellectual supremacy of Man; and by the zoologists, on the ground of its incompatibility with natural affinities and with the true principles of classification? Separated as a group of ordinal value, placed at the same distance from the ape as the latter from the carnivore, Man is at once too near and too distant from the higher mammalia--too near if we take into account those elevated faculties, which, raising Man above all other organised beings, accord to him not only the first, but a separate place in the creation--too far if we merely consider the organic affinities which unite him with the quadrumana; with the apes especially, which, in a purely physical point of view, approach Man more nearly than they do the lemurs." "What, then, is this order of Bimana of Blumenbach and Cuvier? An impracticable compromise between two opposite and irreconcilable systems--between two orders of ideas which are clearly expressed in the language of natural history by these two words: the human KINGDOM and the human FAMILY. It is one of those would-be via media propositions which, once seen through, satisfy no one, precisely because they are intended to please everybody; half-truths, perhaps, but also half-falsehoods; for what, in science, is a half-truth but an error?" Isidore G. St. Hilaire then proceeds to show how, in spite of the great authority of Blumenbach and Cuvier, a large proportion of modern zoologists of note have rejected the order Bimana, and have regarded Man simply as a family of one and the same order, Primates. TERM "QUADRUMANOUS," WHY DECEPTIVE. Even the term "Quadrumanous" has lately been shown by Professor Huxley, in a lecture delivered by him in the spring of 1860-61, which I had the good fortune to hear, to have proved a fertile source of popular delusion, conveying ideas which the great anatomists Blumenbach and Cuvier never entertained themselves, namely, that in the so-called Quadrumana the extremities of the hind-limbs bear a real resemblance to the human hands, instead of corresponding anatomically with the human feet. As this subject bears very directly on the question, how far Man is entitled, in a purely zoological classification, to rank as an order apart, I shall proceed to cite, in an abridged form, the words of the lecturer above alluded to.* (* Professor Huxley's third lecture "On the Motor Organs of Man compared with those of other Animals," delivered in the Royal School of Mines, in Jermyn Street (March 1861) has been embodied with the rest of the course in his work entitled "Evidence as to Man's Place in Nature.") "To gain," he observes, "a precise conception of the resemblances and differences of the hand and foot, and of the distinctive characters of each, we must look below the skin, and compare the bony framework and its motor apparatus in each. "The foot of Man is distinguished from his hand by:-- "1. The arrangement of the tarsal bones. "2. By having a short flexor and a short extensor muscle of the digits. "3. By possessing the muscle termed peronaeus longus. "And if we desire to ascertain whether the terminal division of a limb in other animals is to be called a foot or a hand, it is by the presence or absence of these characters that we must be guided, and not by the mere proportions, and greater or lesser mobility of the great toe, which may vary indefinitely without any fundamental alteration in the structure of the foot. Keeping these considerations in mind, let us now turn to the limbs of the Gorilla. The terminal division of the fore-limb presents no difficulty--bone for bone, and muscle for muscle, are found to be arranged precisely as in Man, or with such minute differences as are found as varieties in Man. The Gorilla's hand is clumsier, heavier, and has a thumb somewhat shorter in proportion than that of Man; but no one has ever doubted its being a true hand. "At first sight, the termination of the hind-limb of the Gorilla looks very hand-like, and as it is still more so in the lower apes, it is not wonderful that the appellation 'Quadrumana,' or four-handed creatures, adopted from the older anatomists by Blumenbach, and unfortunately rendered current by Cuvier, should have gained such wide acceptance as a name for the ape order. But the most cursory anatomical investigation at once proves that the resemblance of the so-called 'hindhand' to a true hand is only skin deep, and that, in all essential respects, the hind-limb of the Gorilla is as truly terminated by a foot as that of Man. The tarsal bones, in all important circumstances of number, disposition, and form, resemble those of Man. The metatarsals and digits, on the other hand, are proportionally longer and more slender, while the great toe is not only proportionally shorter and weaker, but its metatarsal bone is united by a far more movable joint with the tarsus. At the same time, the foot is set more obliquely upon the leg than in Man. "As to the muscles, there is a short flexor, a short extensor, and a peronaeus longus, while the tendons of the long flexors of the great toe and of the other toes are united together and into an accessory fleshy bundle. "The hind-limb of the Gorilla, therefore, ends in a true foot with a very movable great toe. It is a prehensile foot, if you will, but is in no sense a hand: it is a foot which differs from that of Man in no fundamental character, but in mere proportions--degree of mobility--and secondary arrangement of its parts. "It must not be supposed, however, that because I speak of these differences as not fundamental, that I wish to underrate their value. They are important enough in their way, the structure of the foot being in strict correlation with that of the rest of the organism; but after all, regarded anatomically, the resemblances between the foot of Man and the foot of the Gorilla are far more striking and important than the differences."* (* Professor Huxley, ibid.) After dwelling on some points of anatomical detail, highly important, but for which I have not space here, the Professor continues--"Throughout all these modifications, it must be recollected that the foot loses no one of its essential characters. Every monkey and lemur exhibits the characteristic arrangement of tarsal bones, possesses a short flexor and short extensor muscle, and a peronaeus longus. Varied as the proportions and appearance of the organ may be, the terminal division of the hind-limb remains in plan and principle of construction a foot, and never in the least degree approaches a hand."* (* Ibid.) For these reasons, Professor Huxley rejects the term "Quadrumana," as leading to serious misconception, and regards Man as one of the families of the Primates. This method of classification he shows to be equally borne out by an appeal to another character on which so much reliance has always been placed in classification, as affording in the mammalia the most trustworthy indications of affinity, namely, the dentition. "The number of teeth in the Gorilla and all the Old World monkeys, except the lemurs, is thirty-two, the same as in Man, and the general pattern of their crowns the same. But besides other distinctions, the canines in all but Man project in the upper or lower jaws almost like tusks. But all the American apes have four more teeth in their permanent set, or thirty-six in all, so that they differ in this respect more from the Old World apes than do these last from Man." If therefore, by reference to this character, we place Man in a separate order, we must make several orders for the apes, monkeys, and lemurs, and so, in regard to the structure of the hands and feet before alluded to, "the Gorilla differs far more from some of the quadrumana than he differs from Man." Indeed, Professor Huxley contends that there is more difference between the hand and foot of the Gorilla and those of the Orang, one of the anthropomorphous apes, than between those of the Gorilla and Man, for "the thumb of the Orang differs by its shortness and by the absence of any special long flexor muscle from that of the Gorilla more than it differs from that of Man." The carpus also of the Orang, like that of most lower apes, contains nine bones, while in the Gorilla, as in Man and the Chimpanzee, there are only eight." Other characters are also given to show that the Orang's foot separates it more widely from the Gorilla than that of the Gorilla separates that ape from Man. In some of the lower apes, the divergence from the human type of hand and foot, as well as from those of the Gorilla, is still greater, as, for example, in the spider-monkey and marmoset."* (* Huxley, ibid. page 29.) If the muscles, viscera, or any other part of the animal fabric, including the brain, be compared, the results are declared to be similar. WHETHER THE STRUCTURE OF THE HUMAN BRAIN ENTITLES MAN TO FORM A DISTINCT SUB-CLASS OF THE MAMMALIA. In consequence of these and many other zoological considerations, the order Bimana had already been declared, in 1856, by Isidore G. St. Hilaire in his history of the science above quoted "to have become obsolete," even though sanctioned by the great names of Blumenbach and Cuvier. But in opposition to the new views Professor Owen announced, the year after the publication of G. St. Hilaire's work, that he had been led by purely anatomical considerations to separate Man from the other Primates and from the mammalia generally as a distinct SUB-CLASS, thus departing farther from the classification of Blumenbach and Cuvier than they had ventured to do from that of Linnaeus. The proposed innovation was based chiefly on three cerebral characters belonging, it was alleged, exclusively to Man and thus described in the following passages of a memoir communicated to the Linnaean Society in 1857, in which all the mammalia were divided, according to the structure of the brain, into four sub-classes, represented by the kangaroo, the beaver, the ape, and Man respectively:-- "In Man, the brain presents an ascensive step in development, higher and more strongly marked than that by which the preceding sub-class was distinguished from the one below it. Not only do the cerebral hemispheres overlap the olfactory lobes and cerebellum, but they extend in advance of the one and farther back than the other. Their posterior development is so marked that anatomists have assigned to that part the character of a third lobe; it is peculiar to the genus Homo, and equally peculiar is the 'posterior horn of the lateral ventricle' and the 'hippocampus minor' which characterises the hind-lobe of each hemisphere. The superficial grey matter of the cerebrum, through the number and depth of its convolutions, attains its maximum of extent in Man. "Peculiar mental powers are associated with this highest form of brain, and their consequences wonderfully illustrate the value of the cerebral character; according to my estimate of which I am led to regard the genus Homo as not merely a representative of a distinct order, but of a distinct sub-class of the mammalia, for which I propose the name of 'Archencephala.'"* (* Owen, "Proceedings of the Linnaean Society" London volume 8 page 20.) The above definition is accompanied in the same memoir by the following note:--"Not being able to appreciate, or conceive, of the distinction between the psychical phenomena of a chimpanzee and of a Boschisman, or of an Aztec with arrested brain-growth, as being of a nature so essential as to preclude a comparison between them, or as being other than a difference of degree, I cannot shut my eyes to the significance of that all-pervading similitude of structure--every tooth, every bone, strictly homologous--which makes the determination of the difference between Homo and Pithecus the anatomist's difficulty; and therefore, with every respect for the author of the Records of Creation,* I follow Linnaeus and Cuvier in regarding mankind as a legitimate subject of zoological comparison and classification." (* The late Archbishop of Canterbury, Dr. Sumner.) [Illustration: Figure 54, 55 and 56. Brain Of Chimpanzee] (FIGURE 54. UPPER SURFACE OF BRAIN OF CHIMPANZEE, DISTORTED (FROM SCHROEDER VAN DER KOLK AND VROLIK.) Scale half the diameter of the natural size. A. Left cerebral hemisphere. B. Right cerebral hemisphere. C. Cerebellum displaced.) (FIGURE 55. SIDE VIEW OF BRAIN OF CHIMPANZEE, DISTORTED (FROM SCHROEDER VAN DER KOLK AND VROLIK.) Scale half the diameter of the natural size. e. The extension of the displaced cerebellum beyond the cerebrum at d.) (FIGURE 56. CORRECT SIDE VIEW OF CHIMPANZEE'S BRAIN (FROM GRATIOLET). Scale half the diameter of the natural size. d. Backward extension of the cerebrum, beyond the cerebellum at e. f. Fissure of Sylvius.) [Illustration: Figure 57 and 58. Chimpanzee and Human Brain] (FIGURE 57. CORRECT VIEW OF UPPER SURFACE OF CHIMPANZEE'S BRAIN (FROM GRATIOLET), in which the cerebrum covers and conceals the cerebellum. Scale half the diameter of the natural size.) (FIGURE 58. SIDE VIEW OF HUMAN BRAIN (FROM GRATIOLET), NAMELY, THAT OF THE BUSHWOMAN CALLED THE HOTTENTOT VENUS. Scale half the diameter of the natural size. A. Left cerebral hemisphere. C. Cerebellum. ff. Fissure of Sylvius.) To illustrate the difference between the human and Simian brain, Professor Owen gave figures of the negro's brain as represented by Tiedemann, an original one of a South American monkey, Midas rufimanus, and one of the chimpanzee (Figure 54), from a memoir published in 1849 by MM. Schroeder van der Kolk and M. Vrolik.* (* "Comptes rendus de l'Academie Royale des Sciences" Amsterdam volume 13.) The selection of Figure 54 was most unfortunate, for three years before, M. Gratiolet, the highest authority in cerebral anatomy of our age, had, in his splendid work on "The Convolutions of the Brain in Man and the Primates" (Paris, 1854), pointed out that, though this engraving faithfully expressed the cerebral foldings as seen on the surface, it gave a very false idea of the relative position of the several parts of the brain, which, as very commonly happens in such preparations, had shrunk and greatly sunk down by their own weight.* (* Gratiolet's words are: "Les plis cerebraux du chimpanze y sont fort bien etudies, malheureusement le cerveau qui leur a servi de modele etait profondement affaisse, aussi la forme generale du cerveau est-elle rendue, dans leurs planches, d'une maniere tout-a-fait fausse." Ibid. page 18.) Anticipating the serious mistakes which would arise from this inaccurate representation of the brain of the ape, published under the auspices of men so deserving of trust as the two above-named Dutch anatomists, M. Gratiolet thought it expedient, by way of warning to his readers, to repeat their incorrect figures (Figures 54 and 55), and to place by the side of them two correct views (Figures 56 and 57) of the brain of the same ape. By reference to these illustrations, as well as to Figure 58, the reader will see not only the contrast of the relative position of the cerebrum and cerebellum, as delineated in the natural as well as in the distorted state, but also the remarkable general correspondence between the chimpanzee brain and that of the human subject in everything save in size. The human brain (Figure 58) here given, by Gratiolet, is that of an African bushwoman, called the Hottentot Venus, who was exhibited formerly in London, and who died in Paris. Respecting this striking analogy of cerebral structure in Man and the apes, Gratiolet says, in the work above cited: "The convoluted brain of Man and the smooth brain of the marmoset resemble each other by the quadruple character of a rudimentary olfactory lobe, a posterior lobe COMPLETELY COVERING THE CEREBELLUM, a well-defined fissure of Sylvius (ff, Figure 56), and lastly a posterior horn in the lateral ventricle. These characters are not met with together except in Man and the apes."* (* Gratiolet, ibid. Avant-propos page 2 1854.) In reference to the other figure of a monkey given by Professor Owen, namely, that of the Midas, one of the marmosets, he states, in 1857 as he had done in 1837, that the posterior part of the cerebral hemispheres "extends, as in most of the quadrumana, over the greater part of the cerebellum."* (* "Proceedings of the Linnaean Society" 1857 page 18 note, and "Philosophical Transactions" 1837 page 93.) In 1859, in his Rede Lecture, delivered to the University of Cambridge, the same illustrations of the ape's brain were given, namely, that of the Midas and the distorted one of the Dutch anatomists already cited (Figure 54).* (* See Appendix M.) Two years later, Professor Huxley, in a memoir "On the Zoological Relations of Man with the Lower Animals," took occasion to refer to Gratiolet's warning, and to cite his criticism on the Dutch plates;* but this reminder appears to have been overlooked by Professor Owen, who six months later came out with a new paper on "The Cerebral Character of Man and the Ape," in which he repeated the incorrect representation of Schroeder van der Kolk and Vrolik, associating it with Tiedemann's figure of a negro's brain, expressly to show the relative and different extent to which the cerebellum is overlapped by the cerebrum in the two cases respectively.** In the ape's brain as thus depicted, the portion of the cerebellum left uncovered is greater than in the lemurs, the lowest type of Primates, and almost as large as in the rodentia, or some of the lowest grades of the mammalia. (* Huxley, "Natural History Review" January 7, 1861 page 76.) (** "Annals and Magazine of Natural History" volume 7 1861 page 456 and Plate 20.) When the Dutch naturalists above mentioned found their figures so often appealed to as authority, by one the weight of whose opinion on such matters they well knew how to appreciate, they resolved to do their best towards preventing the public from being misled. Accordingly, they addressed to the Royal Academy of Amsterdam a memoir "On the brain of an Orang-outang" which had just died in the Zoological Gardens of that city.* (* This paper is reprinted in the original French in the "Natural History Review" volume 2 1862 page 111.) The dissection of this ape, in 1861, fully bore out the general conclusions at which they had previously arrived in 1849, as to the existence both in the human and the simian brain of the three characters, which Professor Owen had represented as exclusively appertaining to Man, namely, the occipital or posterior lobe, the hippocampus minor, and the posterior cornu. These last two features consist of certain cavities and furrows in the posterior lobes, which are caused by the foldings of the brain, and are only visible when it is dissected. MM. Schroeder van der Kolk and Vrolik took this opportunity of candidly confessing that M. Gratiolet's comments on the defects of their two figures (Figures 54 and 55) were perfectly just, and they expressed regret that Professor Owen should have overstated the differences existing between the brain of Man and the Quadrumana, "led astray, as they supposed, by his zeal to combat the Darwinian theory respecting the transformation of species," a doctrine against which they themselves protested strongly, saying that it belongs to a class of speculations which are sure to be revived from time to time, and are always "peculiarly seductive to young and sanguine minds."* (* Ibid. page 114.) As the two memoirs before alluded to by us, the one by Mr. Darwin on "Natural Selection," and the other by Mr. Wallace "On the Tendency of Varieties to depart indefinitely from the original Type," did not appear till 1858, a year after Professor Owen's classification of the mammalia, and as Darwin's "Origin of Species" was not published till another year had elapsed, we cannot accept the explanation above offered to us of the causes which led the founder of the sub-class Archencephala to seek for new points of distinction between the human and simian brains; but the Dutch anatomists may have fallen into this anachronism by having just read, in the paper by Professor Owen in the "Annals," some prefatory allusions to "the Vestiges of Creation," "Natural Selection, and the question whether man be or be not a descendant of the ape." The number of original and important memoirs to which this discussion on the cerebral relations of Man to the Primates has already given rise in less than five years, must render the controversy for ever memorable in the history of Comparative Anatomy.* (* Rolleston, "Natural History Review" April 1861. Huxley, on "Brain of Ateles" "Proceedings of the Zoological Society" 1861. Flower, "Posterior Lobe in Quadrumana" etc., "Philosophical Transactions" 1862. Id. "Javan Loris" "Proceedings of the Zoological Society" 1862. Id. on "Anatomy of Pithecia" ibid. 1862.) In England alone, no less than fifteen genera of the Primates (the subjects having been almost all furnished by that admirable institution the Zoological Gardens of London) have been anatomically examined, and they include nearly all the leading types of structure of the Old and New World apes and monkeys, from the most anthropoid form to that farthest removed from Man; in other words, from the Chimpanzee to the Lemur. These are:-- Troglodytes (Chimpanzee). Pithecus (Orang). Hylobates (Gibbon). Semnopithecus. Cercopithecus. Macacus. Cynocephalus (Baboon). Ateles (Spider Monkey). Cebus (Capuchin Monkey). Pithecia (Saki). Nyctipithecus (Douricouli). Hapale (Marmoset). Otolicnus. Stenops. Lemur. In July 1861 Mr. Marshall, in a paper on the brain of a young Chimpanzee, which he had dissected immediately after its death, gave a series of photographic drawings, showing that when the parts are all in a fresh state, the posterior lobe of the cerebrum, instead of simply covering the cerebellum, is prolonged backwards beyond it even to a greater extent than in Gratiolet's figure, 56, and, what is more in point, in a greater degree relatively speaking (at least in the young state of the animal) than in Man. In fact, "the projection is to the extent of about one-ninth of the total length of the cerebrum, whereas the average excess of overlapping is only one-eleventh in the human brain."* (* Marshall, "Natural History Review" July 1861. See also on this subject Professor Rolleston on the slight degree of backward extension of the cerebrum in some races of Man. "Medical Times" October 1862, page 419.) The same author gives an instructive account of the manner in which displacement and distortion take place when such brains are preserved in spirits as in the ordinary preparations of the anatomist. Mr. Flower, in a recent paper on the posterior lobe of the cerebrum in the Quadrumana,* remarks, that although Tiedemann had declared himself unable in 1821 to detect the hippocampus minor or the posterior cornu of the lateral ventricle in the brain of a Macacus dissected by him, Cuvier, nevertheless, mentions the latter as characteristic of Man and the apes, and M. Serres in his well-known work on the brain in 1826, has shown in at least four species of apes the presence of both the hippocampus minor and the posterior cornu. (* "Philosophical Transactions" 1862 page 185.) Tiedemann had expressly stated that "the third or hinder lobe in the ape covered the cerebellum as in Man,"* and as to his negative evidence in respect to the internal structure of that lobe, it can have no weight whatever against the positive proofs obtained to the contrary by a host of able observers. Even before Tiedemann's work was published, Kuhl had dissected, in 1820, the brain of the spider-monkey (Ateles beelzebuth), and had given a figure of a long posterior cornu to the lateral ventricle, which he had described as such.** (* Tiedemann, "Icones cerebri Simiarum" etc. page 48.) (** "Beitrage zur Zoologie" etc. Frankfurt am Main 1820.) The general results arrived at by the English anatomists already cited, and by Professor Rolleston in various papers on the same subject, have thus been briefly stated by Professor Huxley:-- "Every lemur which has yet been examined has its cerebellum partially visible from above, and its posterior lobe, with the contained posterior cornu and hippocampus minor, more or less rudimentary. Every marmoset, American monkey, Old World monkey, baboon, or man-like ape, on the contrary, has its cerebellum entirely hidden, and possesses a large posterior cornu, with a well-developed hippocampus minor. "In many of these creatures, such as the Saimiri (Chrysothrix), the cerebral lobes overlap and extend much farther behind the cerebellum in proportion than they do in Man."* (* Huxley, "Evidence as to Man's place in Nature" page 97.) It is by no means pretended that these conclusions of British observers as to the affinity in cerebral structure of Man and the Primates are new, but on the contrary that they confirm the inductions previously made by the principal continental teachers of the last and present generations, such as Tiedemann, Cuvier, Serres, Leuret, Wagner, Schroeder van der Kolk, Vrolik, Gratiolet, and others. At a late meeting of the British Association (1862), Professor Owen read a paper "On the brain and limb characters of the Gorilla as contrasted with those of Man"* in which, he observes, that in the gorilla the cerebrum "extends over the cerebellum, not beyond it." (* Medical Times and Gazette" October 1862 page 373.) This statement, although slightly at variance with one published the year before (1861) by Professor Huxley, who maintains that it does project beyond, is interesting as correcting the description of the same brain given by Professor Owen in that year, in a lecture to the Royal Institution, in which a considerable part of the cerebellum of the gorilla was represented as uncovered.* (* "Athenaeum" Report of Royal Institution Lecture, March 23, 1861, and reference to it by Professor Owen as to Gorilla, ibid. March 30 page 434.) In the same memoir, it is remarked that in the Maimon Baboon the cerebrum not only covers but "extends backwards even beyond the cerebellum."* (* For Report of Professor Owen's Cambridge British Association paper see "Medical Times" October 11, 1862 page 373.) This baboon, therefore, possesses a posterior lobe, according to every description yet given of such a lobe, including a new definition of the same lately proposed by Professor Owen. For the posterior lobe was formerly considered to be that part of the cerebrum which covers the cerebellum, whereas Professor Owen defines it as that part which covers the posterior third of the cerebellum, and extends beyond it. We may, therefore, consider the attempt to distinguish the brain of Man from that of the ape on the ground of newly-discovered cerebral characters, presenting differences in kind, as virtually abandoned by its originator, and if the sub-class Archencephala is to be retained, it must depend on differences in degree, as, for example, the vast increase of the brain in Man, as compared with that of the highest ape, "in absolute size, and the still greater superiority in relative size to the bulk and weight of the body."* (* Owen, ibid. page 373.) If we ask why this character, though well known to Cuvier and other great anatomists before our time, was not considered by them to entitle Man, physically considered, to claim a more distinct place in the group called Primates than that of a separate order, or, according to others, a separate genus or family only, we shall find the answer thus concisely stated by Professor Huxley in his new work, before cited:-- "So far as I am aware, no human cranium belonging to an adult man has yet been observed with a less cubical capacity than 62 cubic inches, the smallest cranium observed in any race of men, by Morton, measuring 63 cubic inches; while on the other hand, the most capacious gorilla skull yet measured has a content of not more than 34 1/2 cubic inches. Let us assume for simplicity's sake, that the lowest man's skull has twice the capacity of the highest gorilla's. No doubt this is a very striking difference, but it loses much of its apparent systematic value, when viewed by the light of certain other equally indubitable facts respecting cranial capacities. "The first of these is, that the difference in the volume of the cranial cavity of different races of mankind is far greater, absolutely, than that between the lowest man and the highest ape, while, relatively, it is about the same; for the largest human skull measured by Morton contained 114 cubic inches, that is to say, had very nearly double the capacity of the smallest, while its absolute preponderance of over 50 cubic inches is far greater than that by which the lowest adult male human cranium surpasses the largest of the gorillas (62 minus 34 1/2 = 27 1/2). Secondly, the adult crania of gorillas which have as yet been measured, differ among themselves by nearly one-third, the maximum capacity being 34.5 cubic inches, the minimum 24 cubic inches; and, thirdly, after making all due allowance for difference of size, the cranial capacities of some of the lower apes fall nearly as much relatively below those of the higher apes, as the latter fall below Man."* (* Huxley, "Evidence as to Man's place in Nature" London 1863 page 78. ) Are we then to conclude that differences in mental power have no intimate connection with the comparative volume of the brain? We cannot draw such an inference, because the highest and most civilised races of Man exceed in the average of their cranial capacity the lowest races, the European brain, for example, being larger than that of the negro, and somewhat more convoluted and less symmetrical, and those apes, on the other hand, which approach nearest to Man in the form and volume of their brain being more intelligent than the Lemurs, or still lower divisions of the mammalia, such as the Rodents and Marsupials, which have smaller brains. But the extraordinary intelligence of the elephant and dog, so far exceeding that of the larger part of the Quadrumana, although their brains are of a type much more remote from the human, may serve to convince us how far we are as yet from understanding the real nature of the dependence of intellectual superiority on cerebral structure. Professor Rolleston, in reference to this subject, remarks, that "even if it were to be proved that the differences between Man's brain and that of the ape are differences entirely of quantity, there is no reason, in the nature of things, why so many and such weighty differences in degree should not amount to a difference in kind. "Differences of degree and differences of kind are, it is true, mutually exclusive terms in the language of the schools; but whether they are so also in the laboratory of Nature, we may very well doubt."* (* Report of a Lecture delivered at the Royal Institution by Professor George Rolleston "On the Brain of Man and Animals" "Medical Gazette" March 15, 1862 page 262.) The same physiologist suggests, that as there is considerable plasticity in the human frame, not only in youth and during growth, but even in the adult, we ought not always to take for granted, as some advocates of the development theory seem to do, that each advance in psychical power depends on an improvement in bodily structure, for why may not the soul, or the higher intellectual and moral faculties, play the first instead of the second part in a progressive scheme? INTELLIGENCE OF THE LOWER ANIMALS COMPARED TO THAT OF MAN. Ever since the days of Leibnitz, metaphysicians who have attempted to draw a line of demarcation between the intelligence of the lower animals and that of Man, or between instinct and reason, have experienced difficulties analogous to those which the modern anatomist encounters when he tries to distinguish the brain of an ape from that of Man by some characters more marked than those of mere size and weight, which vary so much in individuals of the same species, whether simian or human. Professor Agassiz, after declaring that as yet we scarcely possess the most elementary information requisite for a scientific comparison of the instincts and faculties of animals with those of Man, confesses that he cannot say in what the mental faculties of a child differ from those of a young chimpanzee. He also observes, that "the range of the passions of animals is as extensive as that of the human mind, and I am at a loss to perceive a difference of kind between them, however much they may differ in degree and in the manner in which they are expressed. The gradations of the moral faculties among the higher animals and Man are, moreover, so imperceptible, that to deny to the first a certain sense of responsibility and consciousness would certainly be an exaggeration of the difference between animals and Man. There exists, besides, as much individuality within their respective capabilities among animals as among Man, as every sportsman, or every keeper of menageries, or every farmer and shepherd can testify, who has had a large experience with wild, or tamed, or domesticated animals. This argues strongly in favour of the existence in every animal of an immaterial principle, similar to that which, by its excellence and superior endowments, places Man so much above animals. Yet the principle exists unquestionably, and whether it be called soul, reason, or instinct, it presents, in the whole range of organised beings, a series of phenomena closely linked together, and upon it are based not only the higher manifestations of the mind, but the very permanence of the specific differences which characterise every organ. Most of the arguments of philosophy in favour of the immortality of Man apply equally to the permanency of this principle in other living beings."* (* Contributions to the "Natural History of the United States of North America" volume 1 part 1 pages 60 and 64.) Professor Huxley, when commenting on a passage in Professor Owen's memoir, above cited, argues that there is a unity in psychical as in physical plan among animated beings, and adds, that although he cannot go so far as to say that "the determination of the difference between Homo and Pithecus is the anatomist's difficulty," yet no impartial judge can doubt that the roots, as it were, of those great faculties which confer on Man his immeasurable superiority above all other animate things are traceable far down into the animate world. The dog, the cat, and the parrot, return love for our love and hatred for our hatred. They are capable of shame and of sorrow, and though they may have no logic nor conscious ratiocination, no one who has watched their ways can doubt that they possess that power of rational cerebration which evolves reasonable acts from the premises furnished by the senses--a process which takes fully as large a share as conscious reason in human activity.* (* "Natural History Review" Number 1 January 1861 page 68.) GROUNDS FOR REFERRING MAN TO A DISTINCT KINGDOM OF NATURE. Few if any of the authors above cited, while they admit so fully the analogy which exists between the faculties of Man and the inferior animals, are disposed to underrate the enormous gap which separates Man from the brutes, and if they scarcely allow him to be referable to a distinct order, and much less to a separate sub-class, on purely physical grounds, it does not follow that they would object to the reasoning of M. Quatrefages, who says, in his work on the "Unity of the Human Species," that Man must form a kingdom by himself if once we permit his moral and intellectual endowments to have their due weight in classification. As to his organisation, he observes, "We find in the mammalia nearly absolute identity of anatomical structure, bone for bone, muscle for muscle, nerve for nerve--similar organs performing like functions. It is not by a vertical position on his feet, the os sublime of Ovid, which he shares with the penguin, nor by his mental faculties, which, though more developed, are fundamentally the same as those of animals, nor by his powers of perception, will, memory, and a certain amount of reason, nor by articulate speech, which he shares with birds and some mammalia, and by which they express ideas comprehended not only by individuals of their own species but often by Man, nor is it by the faculties of the heart, such as love and hatred, which are also shared by quadrupeds and birds, but it is by something completely foreign to the mere animal, and belonging exclusively to Man, that we must establish a separate kingdom for him (page 21). These distinguishing characters," he goes on to say, "are the abstract notion of good and evil, right and wrong, virtue and vice, or the moral faculty, and a belief in a world beyond ours, and in certain mysterious beings, or a Being of a higher nature than ours, whom we ought to fear or revere; in other words, the religious faculty."--page 23. By these two attributes the moral and the religious, not common to man and the brutes, M. Quatrefages proposes to distinguish the human from the animal kingdom. But he omits to notice one essential character, which Dr. Sumner, the late Archbishop of Canterbury, brought out in strong relief fifty years ago in his "Records of Creation." "There are writers," he observes, "who have taken an extraordinary pleasure in levelling the broad distinction which separates Man from the Brute Creation. Misled to a false conclusion by the infinite variety of Nature's productions, they have described a chain of existence connecting the vegetable with the animal world, and the different orders of animals one with another, so as to rise by an almost imperceptible gradation from the tribe of Simiae to the lowest of the human race, and from these upwards to the most refined. But if a comparison were to be drawn, it should be taken, not from the upright form, which is by no means confined to mankind, nor even from the vague term reason, which cannot always be accurately separated from instinct, but from that power of progressive and improvable reason, which is Man's peculiar and exclusive endowment." "It has been sometimes alleged, and may be founded on fact, that there is less difference between the highest brute animal and the lowest savage than between the savage and the most improved Man. But, in order to warrant the pretended analogy, it ought to be also true that this lowest savage is no more capable of improvement than the Chimpanzee or Orang-outang." "Animals," he adds, "are born what they are intended to remain. Nature has bestowed upon them a certain rank, and limited the extent of their capacity by an impassable decree. Man she has empowered and obliged to become the artificer of his own rank in the scale of beings by the peculiar gift of improvable reason."* (* "Records of Creation" volume 2 chapter 2 2nd edition 1816.) We have seen that Professor Agassiz, in his "Essay on Classification," above cited, speaks of the existence in every animal of "an immaterial principle similar to that which, by its excellence and superior endowments, places man so much above animals;" and he remarks, "that most of the arguments of philosophy in favour of the immortality of Man, apply equally to the permanency of this principle in other living beings." Although the author has no intention by this remark to impugn the truth of the great doctrine alluded to, it may be well to observe, that if some of the arguments in favour of a future state are applicable in common to Man and the lower animals, they are by no means those which are the weightiest and most relied on. It is no doubt true that, in both, the identity of the individual outlasts many changes of form and structure which take place during the passage from the infant to the adult state, and from that to old age, and the loss again and again of every particle of matter which had entered previously into the composition of the body during its growth, and the substitution of new elements in their place, while the individual remains always the same, carries the analogy a step farther. But beyond this we cannot push the comparison. We cannot imagine this world to be a place of trial and moral discipline for any of the inferior animals, nor can any of them derive comfort and happiness from faith in a hereafter. To Man alone is given this belief, so consonant to his reason, and so congenial to the religious sentiments implanted by nature in his soul, a doctrine which tends to raise him morally and intellectually in the scale of being, and the fruits of which are, therefore, most opposite in character to those which grow out of error and delusion. The opponents of the theory of transmutation sometimes argue that, if there had been a passage by variation from the lower Primates to Man, the geologist ought ere this to have detected some fossil remains of the intermediate links of the chain. But what we have said respecting the absence of gradational forms between the Recent and Pliocene mammalia may serve to show the weakness in the present state of science of any argument based on such negative evidence, especially in the case of Man, since we have not yet reached those pages of the great book of nature, in which alone we have any right to expect to find records of the missing links alluded to. The countries of the anthropomorphous apes are the tropical regions of Africa, and the islands of Borneo and Sumatra, lands which may be said to be quite unknown in reference to their Pliocene and Pleistocene mammalia. Man is an old-world type, and it is not in Brazil, the only equatorial region where ossiferous caverns have yet been explored, that the discovery, in a fossil state, of extinct forms allied to the human, could be looked for. Lund, a Danish naturalist, found in Brazil, not only extinct sloths and armadilloes, but extinct genera of fossil monkeys, but all of the American type, and, therefore, widely departing in their dentition and some other characters from the Primates of the old world. At some future day, when many hundred species of extinct quadrumana may have been brought to light, the naturalist may speculate with advantage on this subject; at present we must be content to wait patiently, and not to allow our judgment respecting transmutation to be influenced by the want of evidence, which it would be contrary to analogy to look for in Pleistocene deposits in any districts, which as yet we have carefully examined. For, as we meet with extinct kangaroos and wombats in Australia, extinct llamas and sloths in South America, so in equatorial Africa, and in certain islands of the East Indian Archipelago, may we hope to meet hereafter with lost types of the anthropoid Primates, allied to the gorilla, chimpanzee, and orang-outang. [44] Europe, during the Pliocene period, seems not to have enjoyed a climate fitting it to be the habitation of the quadrumanous mammalia; but we no sooner carry back our researches into Miocene times, where plants and insects, like those of Oeningen, and shells, like those of the Faluns of the Loire, would imply a warmer temperature both of sea and land, than we begin to discover fossil apes and monkeys north of the Alps and Pyrenees. Among the few species already detected, two at least belong to the anthropomorphous class. One of these, the Dryopithecus of Lartet, a gibbon or long-armed ape, about equal to man in stature, was obtained in the year 1856 in the Upper Miocene strata at Sansan, near the foot of the Pyrenees in the South of France, and one bone of the same ape is reported to have been since procured from a deposit of corresponding age at Eppelsheim, near Darmstadt, in a latitude answering to that of the southern counties of England.* (* Owen, "Geologist" November 1862.) But according to the doctrine of progression it is not in these Miocene strata, but in those of Pliocene and Pleistocene date, in more equatorial regions, that there will be the greatest chance of discovering hereafter some species more highly organised than the gorilla and chimpanzee. The only reputed fossil monkey of Eocene date, namely, that found in 1840 at Kyson, in Suffolk, and so determined by Professor Owen, has recently been pronounced by the same anatomist, after re-examination, and when he had ampler materials at his command, to be a pachyderm. M. Rutimeyer,* however, an able osteologist, referred to in the earlier chapters of this work, has just announced the discovery in Eocene strata, in the Swiss Jura, of a monkey allied to the lemurs, but as he has only obtained as yet a small fragment of a jaw with three molar teeth, we must wait for fuller information before we confidently rely on the claims of his Coenopithecus lemuroides to take rank as one of the Primates. (* Rutimeyer, "Eocene Saugethiere" Zurich 1862.) HALLAM ON MAN'S PLACE IN THE CREATION. Hallam, in his "Literature of Europe," after indulging in some profound reflections on "the thoughts of Pascal," and the theological dogmas of his school respecting the fallen nature of Man, thus speaks of Man's place in the creation--"It might be wandering from the proper subject of these volumes if we were to pause, even shortly, to inquire whether, while the creation of a world so full of evil must ever remain the most inscrutable of mysteries, we might not be led some way in tracing the connection of moral and physical evil in mankind, with his place in that creation, and especially, whether the law of continuity, which it has not pleased his Maker to break with respect to his bodily structure, and which binds that, in the unity of one great type, to the lower forms of animal life by the common conditions of nourishment, reproduction, and self-defence, has not rendered necessary both the physical appetites and the propensities which terminate in self; whether again the superior endowments of his intellectual nature, his susceptibility of moral emotion, and of those disinterested affections which, if not exclusively, he far more intensely possesses than an inferior being--above all, the gifts of conscience and a capacity to know God, might not be expected, even beforehand, by their conflict with the animal passions, to produce some partial inconsistencies, some anomalies at least, which he could not himself explain in so compound a being. Every link in the long chain of creation does not pass by easy transition into the next. There are necessary chasms, and, as it were, leaps from one creature to another, which, though no exceptions to the law of continuity, are accommodations of it to a new series of being. If Man was made in the image of God, he was also made in the image of an ape. The framework of the body of him who has weighed the stars and made the lightning his slave, approaches to that of a speechless brute, who wanders in the forests of Sumatra. Thus standing on the frontier land between animal and angelic natures, what wonder that he should partake of both!"* (* Hallam, "Introduction to the Literature of Europe" etc. volume 4 page 162.) The law of continuity here spoken of, as not being violated by occasional exceptions, or by leaps from one creature to another, is not the law of variation and natural selection above explained (Chapter 21), but that unity of plan supposed to exist in the Divine Mind, whether realised or not materially and in the visible creation, of which the "links do not pass by an easy transition" the one into the other, at least as beheld by us. Dr. Asa Gray, an eminent American botanist, to whom we are indebted for a philosophical essay of great merit on the "Origin of Species by Variation and Natural Selection," has well observed, when speaking of the axiom of Leibnitz, "Natura non agit saltatim," that nature secures her ends and makes her distinctions, on the whole, manifest and real, but without any important breaks or long leaps. "We need not wonder that gradations between species and varieties should occur, or that genera and other groups should not be absolutely limited, though they are represented to be so in our systems. The classifications of the naturalist define abruptly where nature more or less blends. Our systems are nothing if not definite." The same writer reminds us that "plants and animals are so different, that the difficulty of the ordinary observer would be to find points of comparison, whereas, with the naturalist, it is all the other way. All the broad differences vanish one by one as we approach the lower confines of the animal and vegetable kingdoms, and no absolute distinction whatever is now known between them."* (* Gray, "Natural Selection not inconsistent with Natural Theology" Trubner & Co. London 1861 page 55.) The author of an elaborate review of Darwin's "Origin of Species," himself an accomplished geologist, declares that if we embrace the doctrine of the continuous variation of all organic forms from the lowest to the highest, including Man as the last link in the chain of being, there must have been a transition from the instinct of the brute to the noble mind of Man; and in that case, "where," he asks, "are the missing links, and at what point of his progressive improvement did Man acquire the spiritual part of his being, and become endowed with the awful attribute of immortality?"* (* Physical Theories of the Phenomena of Life "Fraser's Magazine" July 1860 page 88.) Before we raise objections of this kind to a scientific hypothesis, it would be well to pause and inquire whether there are no analogous enigmas in the constitution of the world around us, some of which present even greater difficulties than that here stated. When we contemplate, for example, the many hundred millions of human beings who now people the earth, we behold thousands who are doomed to helpless imbecility, and we may trace an insensible gradation between them and the half-witted, and from these again to individuals of perfect understanding, so that tens of thousands must have existed in the course of ages, who in their moral and intellectual condition, have exhibited a passage from the irrational to the rational, or from the irresponsible to the responsible. Moreover we may infer from the returns of the Registrar General of births and deaths in Great Britain, and from Quetelet's statistics of Belgium, that one-fourth of the human race die in early infancy, nearly one-tenth before they are a month old; so that we may safely affirm that millions perish on the earth in every century, in the first few hours of their existence. To assign to such individuals their appropriate psychological place in the creation is one of the unprofitable themes on which theologians and metaphysicians have expended much ingenious speculation. The philosopher, without ignoring these difficulties, does not allow them to disturb his conviction that "whatever is, is right," nor do they check his hopes and aspirations in regard to the high destiny of his species; but he also feels that it is not for one who is so often confounded by the painful realities of the present, to test the probability of theories respecting the past, by their agreement or want of agreement with some ideal of a perfect universe which those who are opposed to opinions may have pictured to themselves. We may also demur to the assumption that the hypothesis of variation and natural selection obliges us to assume that there was an absolutely insensible passage from the highest intelligence of the inferior animals to the improvable reason of Man. The birth of an individual of transcendent genius, of parents who have never displayed any intellectual capacity above the average standard of their age or race, is a phenomenon not to be lost sight of, when we are conjecturing whether the successive steps in advance by which a progressive scheme has been developed may not admit of occasional strides, constituting breaks in an otherwise continuous series of psychical changes. The inventors of useful arts, the poets and prophets of the early stages of a nation's growth, the promulgators of new systems of religion, ethics, and philosophy, or of new codes of laws, have often been looked upon as messengers from Heaven, and after their death have had divine honours paid to them, while fabulous tales have been told of the prodigies which accompanied their birth. Nor can we wonder that such notions have prevailed when we consider what important revolutions in the moral and intellectual world such leading spirits have brought about; and when we reflect that mental as well as physical attributes are transmissible by inheritance, so that we may possibly discern in such leaps the origin of the superiority of certain races of mankind. In our own time the occasional appearance of such extraordinary mental powers may be attributed to atavism; but there must have been a beginning to the series of such rare and anomalous events. If, in conformity with the theory of progression, we believe mankind to have risen slowly from a rude and humble starting point, such leaps may have successively introduced not only higher and higher forms and grades of intellect, but at a much remoter period may have cleared at one bound the space which separated the highest stage of the unprogressive intelligence of the inferior animals from the first and lowest form of improvable reason manifested by Man. To say that such leaps constitute no interruption to the ordinary course of nature is more than we are warranted in affirming. In the case of the occasional birth of an individual of superior genius there is certainly no break in the regular genealogical succession; and when all the mists of mythological fiction are dispelled by historical criticism, when it is acknowledged that the earth did not tremble at the nativity of the gifted infant and that the face of heaven was not full of fiery shapes, still a mighty mystery remains unexplained, and it is the ORDER of the phenomena, and not their CAUSE, which we are able to refer to the usual course of nature. Dr. Asa Gray, in the excellent essay already cited, has pointed out that there is no tendency in the doctrine of Variation and Natural Selection to weaken the foundations of Natural Theology, for, consistently with the derivative hypothesis of species, we may hold any of the popular views respecting the manner in which the changes of the natural world are brought about. We may imagine "that events and operations in general go on in virtue simply of forces communicated at the first, and without any subsequent interference, or we may hold that now and then, and only now and then, there is a direct interposition of the Deity; or, lastly, we may suppose that all the changes are carried on by the immediate orderly and constant, however infinitely diversified, action of the intelligent, efficient Cause." They who maintain that the origin of an individual, as well as the origin of a species or a genus, can be explained only by the direct action of the creative cause, may retain their favourite theory compatibly with the doctrine of transmutation. Professor Agassiz, having observed that, "while human thought is consecutive, divine thought is simultaneous," Dr. Asa Gray has replied that, "if divine thought is simultaneous, we have no right to affirm the same of divine action." The whole course of nature may be the material embodiment of a preconcerted arrangement; and if the succession of events be explained by transmutation, the perpetual adaptation of the organic world to new conditions leaves the argument in favour of design, and therefore of a designer, as valid as ever; "for to do any work by an instrument must require, and therefore presuppose, the exertion rather of more than of less power, than to do it directly."* (* Asa Gray, "Natural Selection not inconsistent with Natural Theology" Trubner & Co. London 1861 page 55.) As to the charge of materialism brought against all forms of the development theory, Dr. Gray has done well to remind us that "of the two great minds of the seventeenth century, Newton and Leibnitz, both profoundly religious as well as philosophical, one produced the theory of gravitation, the other objected to that theory, that it was subversive of natural religion."* (* Ibid. page 31.) It may be said that, so far from having a materialistic tendency, the supposed introduction into the earth at successive geological periods of life--sensation--instinct--the intelligence of the higher mammalia bordering on reason--and lastly the improvable reason of Man himself, presents us with a picture of the ever-increasing dominion of mind over matter. NOTES. [Footnote 1: The classification of the strata above the Chalk, as at present employed by the majority of British geologists, is merely a slight modification of that proposed by Lyell in 1833. The subdivisions generally recognised are as follows (Lake and Rastall, "Textbook of Geology," London, 1910, page 438):-- Neogene: Pleistocene Pliocene Miocene. Palaeogene: Oligocene Eocene. This differs chiefly from Lyell's classification in the introduction of the term Oligocene for the upper part of the original Eocene, which was somewhat unwieldy. In the earlier editions of the "Antiquity of Man" and of the "Principles of Geology," the strata here classed as Pleistocene were designated as Post-pliocene. The term "diluvium," now obsolete in Britain but still lingering on the Continent, is equivalent to Pleistocene. This subdivision is still sometimes separated from the Tertiary, as the Quaternary epoch. This, however, is unnecessary and indeed objectionable, as attributing too great importance to relatively insignificant deposits. There is no definite break, either stratigraphical or palaeontological, at the top of the Pliocene, and it is most natural to regard the Tertiary epoch as still in progress. Equally unnecessary is the separation of the post-glacial deposits as "Recent," a distinction which still prevails in many quarters, apparently with the sole object of adding another name to an already over-burdened list.] [Footnote 2: The table of strata here printed is not that given by Lyell in the later editions of the "Antiquity of Man." This would have required so much explanation in the light of modern work that it was thought better to abolish it altogether and to substitute an entirely new table, which is to some extent a compromise between the numerous classifications now in vogue. In this form it is only strictly applicable to the British Isles, though the divisions adopted in other countries are generally similar, and in many cases identical.] [Footnote 3: A similar succession of forest-beds, five in number, has been observed in the peat of the Fenland, near Ely. Each bed consists for the most part of a single species of tree, and a definite succession of oak, yew, Scotch fir, alder, and willow has been made out. The forest beds are supposed to indicate temporarily drier conditions, due either to changes of climate or to slight uplift of the land, the growth of peat being renewed during periods of damp climate or of depression of the land. (See Clement Reid, "Submerged Forests," Cambridge, 1913.)] [Footnote 4: Since the "Stone Age," in the sense in which the term is here employed, obviously occupied an enormous lapse of time and embraced very different stages of culture, it has been found convenient to subdivide it into two primary subdivisions. For these Lord Avebury proposed in 1865 the terms Palaeolithic and Neolithic. (" Prehistoric Times," London, 1865, page 60.) The first comprises the ages during which man fabricated flint implements solely by chipping, whereas the implements of Neolithic Age are polished by rubbing. But there is another and more fundamental distinction. Palaeolithic man was exclusively a hunter, and consequently nomadic in his habits; Neolithic man possessed domesticated animals and cultivated crops. A pastoral and agricultural life implies a settled abode, and these are found, for example, in the lake-villages of Switzerland. The "kitchen-middens" of Denmark also indicate long continuance in one place, in this instance the seashore.] [Footnote 5: The famous case of the so-called Temple of Serapis at Pozzuoli, has given rise to a considerable literature. The subject is discussed by Suess at length ("Des Antlitz der Erde," Vienna, 1888, volume 2 page 463, or English translation, "The Face of the Earth," Oxford, 1904). This author shows that the whole region is highly volcanic, and consequently very liable to disturbance, much relative movement of land and sea having occurred within historic times. Hence the facts here observed cannot be taken as evidence for any general upward or downward movement of wide-spread or universal extent.] [Footnote 6: Darwin, "Voyage of the Beagle," chapter 14, and a much fuller account in the same author's "Geological Observations on the Volcanic Islands and Parts of South America Visited during the Voyage of H.M.S. Beagle," chapter 9.] [Footnote 7: For a full discussion of the evidence for and against continental elevation and subsidence in general, and as affecting the British Isles and Scandinavia in particular, see Sir A. Geikie's Presidential Address to the Geological Society for 1904 (" Proceedings of the Geological Society"' volume 60, 1904, pages 80 to 104.). Here it is shown that the oldest raised beaches of Scotland are pre-glacial, and the same also holds for the south of Ireland.] [Footnote 8: The argument here employed is fallacious, since the mere existence of a distinct beach implies a pause in the movement and a long continuance at one level. It is impossible to form any estimate of the lapse of time necessary for the building up of a beach-terrace. We can only, in some cases, obtain a measure of the time that elapsed between the formation of two successive beaches, as in this instance.] [Footnote 9: The "strand lines," or raised beaches of Norway, have given rise to much discussion, of which a summary will be found in the address cited in Note 7.] [Footnote 10: A considerable number of skulls and skeletons of the Neanderthal type have now been found in different parts of Southern Europe, extending from Belgium to Gibraltar and Croatia, and it is now known that this type of skull is associated with flint implements of Mousterian Age. (See Note 12.)] [Footnote 11: The most important discovery of recent years in this connection is that made in Sussex by Mr. C. Dawson and Dr. A. Smith Woodward; this find is described in great detail in the "Quarterly Journal of the Geological Society," volume 69, 1913, pages 117 to 151. At a height of about 80 feet above the present level of the River Ouse, at Piltdown, near Uckfield, is a gravel, containing many brown flints of peculiar character, some of which are implements of Chellean or earlier type, associated with some remains of Pleistocene animals and a few of older date, derived from Pliocene deposits. Embedded in this gravel were found fragments of a human skull and lower jaw of very remarkable type, showing in some respects distinctly simian characters, while in other respects it is less ape-like than the Mousterian skulls of Neanderthal and other localities. For this form the name of Eoanthropus has been proposed, thus constituting a new genus of the Hominidae.] [Footnote 12: It will be well at this point to give a brief summary of the modern classification of the Palaeolithic implement-bearing deposits of Europe. From the labours of many geologists and prehistoric archaeologists, especially in France, a definite succession of types of implement has been established, and in some cases it has been found possible to correlate these with actual human remains and with certain well-marked events in the physical history of Pleistocene times, especially with the advance and retreat of ice-sheets. The present state of our knowledge is admirably summarised by Professor Sollas ("Ancient Hunters," London, 1911), and from that work the following note is condensed. The stages of Palaeolithic culture now recognised are as follows:-- Azilian Magdalenian Solutrean Aurignacian Mousterian Acheulean Chellean Strepyan Mesvinian. Below the Mesvinian comes the nebulous region of "eoliths," which are not yet definitely proved to be of human workmanship. The Neanderthal skull belongs to the Mousterian stage, but the oldest known definitely human remain, the jaw from the Mauer sands near Heidelberg, may be older than any of these, indeed by some it is assigned to the first interglacial period of Penck and Bruckner (see Note 32). For figures of the types of implement characterising each period, see "Guide to the Antiquities of the Stone Age in the Department of British and Medieval Antiquities," British Museum, 2nd edition, London, 1911, pages 1 to 74. This publication gives an admirable summary of recent knowledge on this subject. For an excellent and critical summary of the latest researches on Palaeolithic man up till the end of the Aurignacian period, see Duckworth, "Prehistoric Man," Cambridge, 1912. See also note 44.] [Footnote 13: Sir John Evans, K.C.B. (1823-1908), was one of the foremost authorities on prehistoric archaeology and a prolific writer on the subject. His best known work is "The Ancient Stone Implements, Weapons, and Ornaments of Great Britain," 2nd edition, 1897.] [Footnote 14: By the expression "Celtic weapons of the stone period" is presumably meant Neolithic implements, with polished surfaces.] [Footnote 15: It has recently been shown that the growth of peat is a very slow process, and at the present time it is in many places either at a standstill or even in a state of retrogression. In the peat-mosses of Scotland, Lewis has traced nine successive layers, marked by different floras. The lowest of these and another at a higher level are distinctly of an arctic character, the intermediate forest beds, on the other hand, indicate periods of milder climate, when the limit of the growth of trees was at a higher level in Scotland than is now the case. From these facts it is certain that the peat-mosses of Scotland and northern England date back at least as far as the later stages of the glacial period, and indicate at least one mild interglacial episode, when the climate was somewhat warmer than it now is. (See Lewis, "Science Progress," volume 2, 1907, page 307.) Hence the statements of the French workmen, here quoted, do not possess much significance.] [Footnote 16: Cyrena fluminalis is very abundant in the gravels of an old terrace of the River Cam, at Barnwell, in the suburbs of Cambridge, and also in glacial gravels at Kelsey Hill in Holderness. It is a very remarkable fact that this shell, now an inhabitant of warm regions, should be so abundant in these Pleistocene deposits, in close association with glacial accumulations.] [Footnote 17: The implement-bearing deposits of Hoxne, in Suffolk, were investigated with great care by a committee of the British Association, and the results were published in a special and detailed report ("The Relation of Palaeolithic Man to the Glacial Epoch," "Report of the British Association," Liverpool, 1896, pages 400 to 415). The deposit consists of a series of lacustrine or fluviatile strata with plant remains, some being arctic in character, resting on Chalky Boulder Clay, and this again on sand. The Palaeolithic deposits are all clearly later than the latest boulder-clay of East Anglia, and between their formation and that of the glacial deposits at least two important climatic changes took place, indicating a very considerable lapse of time. Mention may conveniently be made here of the supposed discovery of the remains of pre-glacial man at Ipswich, which appears to be founded on errors of observation. The boulder-clay above the interment is, according to the best authorities, merely a landslip or flow.] [Footnote 18: It has been suggested with a considerable degree of probability, that in Auvergne volcanic eruptions persisted even into historic times. The subject is obscure, depending on the interpretation of difficult passages in two Latin chronicles of the fifth century. The most obvious meaning of both passages would certainly appear to be the occurrence of volcanic eruptions and earthquakes, but attempts have been made to explain them as referring to some artificial conflagration, possibly the burning of a town by an invader. (See Bonney, "Volcanoes," 3rd edition, London, 1913, page 129.)] [Footnote 19: In the early days of glacial geology in Britain, it was commonly accepted that the phenomena could be most satisfactorily explained on the hypothesis of a general submergence of the northern parts of the country to a depth of many hundreds of feet, and this in spite of the original comparison by Agassiz of the glacial deposits of Britain to those of the Alps. In later times, however, a school of geologists arose who attributed the glaciation of Britain to land-ice of the Continental or Greenland type. Of late years this school has been dominant in British geology, with a few notable exceptions, of whom the most important is Professor Bonney. The difficulties presented by both theories are almost equally great, and at the present time, in spite of the vehemence of the supporters of the land-ice theory, it is impossible to hold any dogmatic views on the subject. Against the doctrine of submergence is the absence of glacial deposits in places where they would naturally be expected to occur if the whole of the British Isles north of the Thames and Bristol Channel had been covered by the sea, together with the very general absence of sea-shells in the deposits. The objections to the land-ice hypothesis are largely of a mechanical nature. If we take into account the lateral extent and the thickness that can be assigned to the ice-sheet, we are at once confronted by very considerable difficulties as to the sufficiency of the driving-power behind the ice. Another great difficulty is the shallowness of the North Sea, in which a comparatively thin mass of ice would run aground at almost any point. It has been calculated that the maximum slope of the surface of the ice from Norway to the English coast could not exceed half a degree, and it is therefore difficult to see what force could compel it to move forward at all, much less to climb steep slopes in the way postulated by the extremists of this school.] [Footnote 20: The most complete account of the geology of the Norfolk coast is contained in "The Geology of Cromer," by Clement Reid ("Memoir of the Geological Survey"). (See also Harmer, "The Pleistocene Period in the Eastern Counties of England," "Geology in the Field, the Jubilee Volume of the Geologists Association," 1909, chapter 4.). Above the Norwich Crag several more subdivisions are now recognised, and the complete succession of the Pliocene and Pleistocene strata of East Anglia may be summarised as follows:-- Pleistocene: Peat and Alluvium Gravel Terraces of the present river systems Gravels of the old river-systems Plateau gravels Chalky boulder-clay Interglacial sands and gravels and Contorted Drift Cromer Till Arctic Plant Bed. Pliocene: Cromer Forest Series Weybourn Crag Chillesford Crag Norwich Crag Red Crag Coralline Crag. [Footnote 21: It is now generally agreed that the tree-stumps in the Cromer Forest bed are not in the position of growth. Many of them are upside down or lying on their sides, and they were probably floated into their present position by the waters of a river flowing to the north. This river was a tributary of the Rhine which then flowed for several hundred miles over a plain now forming the bed of the North Sea, collecting all the drainage of eastern England, and debouching into the North Atlantic somewhere to the south of the Faroe Isles. (See Harmer, "The Pleistocene Period in the Eastern Counties of England," "Geological Association Jubilee Volume," London, 1909, pages 103 to 123.)] [Footnote 22: Of late years an enormous number of characteristic rocks from Norway and Sweden have been recognised in the drifts of Eastern England, as far south as Essex and Middlesex. One of the most easily identifiable types is the well-known Rhombporphyry of the Christiania Fjord, a rock which occurs nowhere else in the world, and is quite unmistakable in appearance. Along with it are many of the distinctive soda-syenites found in the same district, the granites of southern Sweden, and many others. The literature of the subject is very large, but many details may be found in the annual reports of the British Association for the last twenty years.] From a study of these erratics it has been found possible to draw important conclusions as to the direction and sequence of the ice streams which flowed over these regions during the different stages of the glacial period.] [Footnote 23: During his first crossing of Greenland from east to west, Nansen attained a height of 9000 feet on a vast expanse of frozen snow, and it is believed that towards the north the surface of this great snow-plateau rises to even greater elevations. The surface of the snow is perfectly clean and free from moraine-material. No rock in situ has been seen in the interior of Greenland at a distance greater than 75 miles from the coast. A great amount of valuable information concerning the glacial conditions of Greenland is to be found in the "Meddelelser om Gronland," a Danish publication, but containing many summaries in French or English. For a good account of the phenomena seen in the coastal region of the west coast, see Drygalski, "Gronland-Expedition," a large monograph published by the Gesellschaft fur physischen Erdkunde, Berlin, 1897.] [Footnote 24: The argument is here considerably understated. The southern point of Greenland, Cape Farewell, is in the same latitude as the Shetland Islands and Christiania, and only one degree north of Stockholm; Disko is in about the same latitude as the North Cape. Hence the inhabited portion of Greenland is in the same latitude as Norway and Sweden, both fertile and well-populated countries. Even in Central Norway, in the Gudbrandsdal and Romsdal, thick forests grow up to a height of at least 3000 feet above sea-level, a much greater elevation than trees now attain in the British Isles. This latter fact is probably to be attributed to the protective effect of thick snow lying throughout the winter.] [Footnote 25: For a summary of the most recent views as to the classification and succession of the glacial deposits of the British Isles, see Lake an Rastall, "Textbook of Geology," London, 1910, pages 466 to 473. Reference may also be made to Jukes-Browne, "The Building of the British Isles," London, 1912, pages 430 to 440.] [Footnote 26: Glacier-lakes are fairly common among the fjords of the west coast of Greenland, and illustrate very well what must have been the state of affairs in Glen Roy at the time of formation of the Parallel Roads.] [Footnote 27: The high-level shell-bearing deposits of Moel Tryfan, Gloppa, near Oswestry, and Macclesfield, have given rise to much controversy between the supporters of submergence and of land-ice. At Moel Tryfan certain sands and gravels, with erratics, at a height of about 1350 feet, contain abundant marine shells, generally much broken. The northern or seaward face of the hill is much plastered with drift, but none is to be found on the landward side, and it is suggested that the shell-bearing material is the ground-moraine of a great ice-sheet that came in from the Irish Sea, and was forced up on to the Welsh coast, just reaching the watershed, but failing to overtop it. With regard to the explanation by submergence, the great objection is the absence of marine drift on the landward side, which is very difficult to explain if the whole had been submerged sufficiently to allow of normal marine deposits at such a great height. The shell beds of Macclesfield and Gloppa are at a less elevation but of essentially similar character. The shell-bearing deposits of Moel Tryfan were examined by a committee of the British Association. (See "Report of the British Association" Dover, 1899, pages 414 to 423.) At the end of this report is an extensive bibliography.] [Footnote 28: During the last forty years the deep-sea dredging expeditions of H. M.S. Challenger and others have shown the abundance and variety of animal life at great depths, especially in the Arctic and Antarctic seas. For a recent summary, see Murray and Hjort, "The Depths of the Ocean," London, 1912.] [Footnote 29: It is now generally admitted that these shell-beds in Wexford are of Pliocene age, and they therefore have no bearing on the subject under discussion.] [Footnote 30: The boulder deposit at Selsey has been described by Mr. Clement Reid ("Quarterly Journal of the Geological Society," volume 48, 1892, page 355). Immediately above the Tertiary beds is a hard greenish clay, full of derived Tertiary fossils and Pleistocene shells with large flints and erratic blocks, some of the latter weighing several tons. They include granite, greenstone, schist, slate, quartzite, and sandstone, and most of them must have been transported for a long distance. Above them are black muds with marine shells, then a shingle beach, and above all the Coombe Rock. (See next note.)] [Footnote 31: The Brighton elephant-bed and its equivalent, the Coombe Rock, are fully described by Clement Reid ("On the Origin of Dry Chalk Valleys and the Coombe Rock," "Quarterly Journal of the Geological Society," volume 43, 1887, page 364). The Coombe Rock is a mass of unstratified flints and Chalk debris filling the lower parts of the dry valleys (Coombes) of the South Downs and gradually passing into the brick-earth (loam) of the coastal plain. It is clearly a torrential accumulation, and is supposed to have been formed while the Chalk was frozen, thus preventing percolation of water and causing the surface water to run off as strong streams. This must have occurred during some part of the glacial period, which would naturally be a period of heavy precipitation. Of very similar origin is the "Head" of Cornwall, a surface deposit often rich in tinstone and other minerals of economic value. The Coombe Rock has recently been correlated with deposits of Mousterian Age.] [Footnote 32: The former extension of the Alpine glaciers and the deposits formed by them have been exhaustively investigated by Penck and Bruckner ("Die Alpen im Eiszeitalter," 3 volumes, Leipzig, 1901 to 1909). In this monumental work the authors claim to have established the occurrence of four periods of advance of the ice, to which they give the names of Gunz, Mindel, Riss, and Wurm glaciations, with corresponding interglacial genial episodes, when the climate was possibly even somewhat warmer than now. Their conclusions and the data on which they are established are summarised by Sollas (" Ancient Hunters," London, 1911, especially pages 18 to 28). For a general account of the glaciers of the Alps and their accompanying phenomena, see Bonney, "The Building of the Alps," London, 1912, pages 103 to 151.] [Footnote 33: At the time of the maximum advance of the ice, during the Riss period of Penck and Bruckner, the terminal moraine of the great glacier of the Rhone extended as far as the city of Lyon, and towards the north-east it became continuous with the similar moraine of the Rhine glacier.] [Footnote 34: For the successive phases of advance and retreat of the Alpine glaciers, see the works quoted in Note 32.] [Footnote 35: The Loess of Central Europe includes deposits of two different ages. According to Penck the "Older Loess" was formed in the period of warm and dry climate that intervened between the third and fourth glacial episodes, while the "Younger Loess" is post-glacial. Both divisions are for the most part aeolian deposits, formed by the redistribution of fine glacial mud originally laid down in water and carried by the wind often to considerable heights. A part, however, of the so-called Loess of northern France, e.g. in the valley of the Somme, is rain-wash, similar in character to the brick-earth of parts of south-eastern England. The Older Loess contains Acheulean implements, while the Younger Loess is of Aurignacian Age. The greatest development of the Loess is in Central Asia and in China. (See Richthofen, "China," Berlin, 1877.) In China the Loess reaches a thickness of several thousand feet, and whole mountain-ranges are sometimes almost completely buried in it. In the deserts of Central Asia the formation of the Loess is still in progress. A very similar deposit, called adobe, is also found in certain parts of the Mississippi valley. The Loess is a fine calcareous silt or clay of a yellowish colour, quite soft and crumbling between the fingers. However, it resists denudation in a remarkable manner, and in China it often stands up in vertical walls hundreds of feet in height. This property is probably assisted by the presence of numerous fine tubes arranged vertically and lined with calcium carbonate; these are supposed to have been formed in the first place by fibrous rootlets.] [Footnote 36: Although highly probable, it cannot yet be regarded as conclusively demonstrated that the Pleistocene glaciations of Europe and of North America were exactly contemporaneous. The ice--sheets in each case radiated from independent centres which were not in the extreme north of either continent, and were not in any way connected with a general polar ice-cap. The European centre was over the Baltic region or the south of Scandinavia, and the American centre in the neighbourhood of Hudson's Bay. The southern margin of the American ice-sheet extended about as far south as latitude 38 degrees north in the area lying south of the Great Lakes, whereas the North European ice barely passed the limit of 50 degrees north in Central Europe. This greater southward extension in America was doubtless correlated with the same causes as now produce the low winter temperatures of the eastern states, especially the cold Newfoundland current. The literature of North American glacial geology has now attained colossal dimensions, and it is impossible to give here even a short abstract of the main conclusions. For a general summary reference may be made to Chamberlin and Salisbury, "Geology," volume 3; "Earth History," London and New York, 1905; or the same authors' "Geology, Shorter Course," London and New York, 1909.] [Footnote 37: During the last fifty years scarcely any geological subject has given rise to a greater amount of speculation than the cause of the Ice Age, and the solution of the problem is still apparently far off. The theories put forward may for convenience be divided into three groups, namely astronomical, geographical, and meteorological. As examples of astronomical explanation, we may take the well-known theory of Adhemar and Crohl, which is founded on changes in the ellipticity of the earth's orbit. This is expounded and amplified by Sir Robert Ball in his "Cause of an Ice Age." The weak point of this theory, which is mathematically unassailable, is that it proves too much, and postulates a constant succession of glacial periods throughout earth-history, and for this there is no evidence. The geographical explanations are chiefly founded on supposed changes in the distribution of sea and land, with consequent diversion of cold and warm currents. Another suggestion is that the glaciated areas had undergone elevation into mountain regions, but this is in conflict with evidence for submergence beneath the sea in certain cases. Meteorological hypotheses, such as that of Harmer, founded on a different arrangement of air pressures and wind-directions, seem to offer the most promising field for exploration and future work, but it is clear that much still remains to be explained.] [Footnote 38: The reptile-bearing Elgin Sandstones are of Triassic Age, and they contain a most remarkable assemblage of strange and eccentric forms, especially Anomodont reptiles resembling those found in the Karroo formation of South Africa.] [Footnote 39: The meaning of this statement is not very clear. The Conifers are not dicotyledons: their seeds contain numerous cotyledons, up to twenty in number, and the whole plant, and especially the reproductive system, belongs to a lower stage of development. The argument here employed is therefore fallacious, and in point of fact the different groups actually appeared in the order postulated by the theory of evolution, namely: (1) Gymnosperms, (2) Monocotyledons, (3) Dicotyledons. See Arber, "The Origin of Gymnosperms," "Science Progress," volume 1, 1906, pages 222 to 237.] [Footnote 40: The part of the manuscript read to Dr. Hooker in 1844 was undoubtedly the "Essay of 1844," forming the second part of the "Foundations of the Origin of Species," a volume published by Sir Francis Darwin on the occasion of the Darwin Centenary at Cambridge in 1909. (See also Darwin's "Life and Letters," volume 2 pages 16 to 18.)] [Footnote 41: This projected larger work, which is often referred to in the "Origin of Species," was never published as such, but Darwin's views on various aspects of evolution were set forth in several later books, such as "The Variation of Animals and Plants under Domestication," "The Descent of Man," "Various Contrivances by which Orchids are Fertilised by Insects," "Movements and Habits of Climbing Plants," "Insectivorous Plants," and others.] [Footnote 42: With this section compare the famous chapter with the same title in the "Origin of Species."] [Footnote 43: No attempt has been made to annotate this chapter, owing to the impossibility of doing so within reasonable compass. Many of the theories here quoted, and the conclusions drawn from them, have not stood the test of time, and recent philological and ethnographical research have clearly shown the danger of attempting to infer the relationships of different peoples from their languages. The modifications undergone by the languages themselves are also subject to influences of such complex character, so largely artificial in their origin, that any attempt to compare them with natural evolution in the organic world must lead to false analogies. The chapter must be regarded as an interesting exposition of one phase of Mid-Victorian scientific thought, but having little real bearing on the subjects discussed in the rest of the book.] [Footnote 44: That the prophecy here given was justified is shown by the discovery in Java in 1891, of the skull and parts of the skeleton of Pithecanthropus erectus, a form which, according to the best authorities, must be regarded as in many ways intermediate between man and the apes, though perhaps with more human than ape-like characteristics. For an account of the circumstances of its discovery and a general description of the remains, see Sollas, "Ancient Hunters," London, 1911, pages 30 to 39 (with many references). Within the last year or two interest in the ancestry of man has been greatly increased, especially by the Piltdown discovery (see Note 11). This has led to a revision of the whole subject, and the views formerly held have undergone a certain amount of modification. It now seems certain that the different types of culture as represented by the succession of stages given in Note 12 do not correspond to a continuous development of one single race of mankind. There is, undoubtedly, a great break between the Mousterian and Aurignacian. Mousterian or Neanderthal man appears to have become extinct, possibly having been exterminated by a migration of the more highly developed Aurignacian race, which may be regarded as the ancestor of modern man in Europe. It appears, therefore, that the really important line of division comes, not as was formerly thought between Palaeolithic and Neolithic, but in the middle of the Palaeolithic between Mousterian and Aurignacian. Hence it appears that our classification will in the near future have to undergo revision, since the stages of culture from Aurignacian to Azilian show a much closer affinity to the Neolithic than they do to the earlier Palaeolithic. At the present time scarcely sufficient data are available to determine the relationship of Pithecanthropus and Eoanthropus to the later types of man. For an excellent summary of the most recent views see Thacker, "The Significance of the Piltdown Discovery," "Science Progress," volume 8, 1913, page 275.] 
2740	----	MORE LETTERS OF CHARLES DARWIN By Charles Darwin A RECORD OF HIS WORK IN A SERIES OF HITHERTO UNPUBLISHED LETTERS EDITED BY FRANCIS DARWIN, FELLOW OF CHRIST'S COLLEGE, AND A.C. SEWARD, FELLOW OF EMMANUEL COLLEGE, CAMBRIDGE IN TWO VOLUMES Transcriber's Notes: All biographical footnotes of both volumes appear at the end of Volume II. All other notes by Charles Darwin's editors appear in the text, in brackets () with a Chapter/Note or Letter/Note number. VOLUME II. DEDICATED WITH AFFECTION AND RESPECT, TO SIR JOSEPH HOOKER IN REMEMBRANCE OF HIS LIFELONG FRIENDSHIP WITH CHARLES DARWIN "You will never know how much I owe to you for your constant kindness and encouragement" CHARLES DARWIN TO SIR JOSEPH HOOKER, SEPTEMBER 14, 1862 MORE LETTERS OF CHARLES DARWIN VOLUME II CHAPTER 2.VII.--GEOGRAPHICAL DISTRIBUTION. 1843-1882 (Continued) (1867-1882.) LETTER 378. J.D. HOOKER TO CHARLES DARWIN. Kew, January 20th, 1867. Prof. Miquel, of Utrecht, begs me to ask you for your carte, and offers his in return. I grieve to bother you on such a subject. I am sick and tired of this carte correspondence. I cannot conceive what Humboldt's Pyrenean violet is: no such is mentioned in Webb, and no alpine one at all. I am sorry I forgot to mention the stronger African affinity of the eastern Canary Islands. Thank you for mentioning it. I cannot admit, without further analysis, that most of the peculiar Atlantic Islands genera were derived from Europe, and have since become extinct there. I have rather thought that many are only altered forms of existing European genera; but this is a very difficult point, and would require a careful study of such genera and allies with this object in view. The subject has often presented itself to me as a grand one for analytic botany. No doubt its establishment would account for the community of the peculiar genera on the several groups and islets, but whilst so many species are common we must allow for a good deal of migration of peculiar genera too. By Jove! I will write out next mail to the Governor of St. Helena for boxes of earth, and you shall have them to grow. Thanks for telling me of having suggested to me the working out of proportions of plants with irregular flowers in islands. I thought it was a deuced deal too good an idea to have arisen spontaneously in my block, though I did not recollect your having done so. No doubt your suggestion was crystallised in some corner of my sensorium. I should like to work out the point. Have you Kerguelen Land amongst your volcanic islands? I have a curious book of a sealer who was wrecked on the island, and who mentions a volcanic mountain and hot springs at the S.W. end; it is called the "Wreck of the Favourite." (378/1. "Narrative of the Wreck of the 'Favourite' on the Island of Desolation; detailing the Adventures, Sufferings and Privations of John Munn; an Historical Account of the Island and its Whale and Sea Fisheries." Edited by W.B. Clarke: London, 1850.) LETTER 379. TO J.D. HOOKER. Down, March 17th, 1867. It is a long time since I have written, but I cannot boast that I have refrained from charity towards you, but from having lots of work...You ask what I have been doing. Nothing but blackening proofs with corrections. I do not believe any man in England naturally writes so vile a style as I do... In your paper on "Insular Floras" (page 9) there is what I must think an error, which I before pointed out to you: viz., you say that the plants which are wholly distinct from those of nearest continent are often very common instead of very rare. (379/1. "Insular Floras," pamphlet reprinted from the "Gardeners' Chronicle," page 9: "As a general rule the species of the mother continent are proportionally the most abundant, and cover the greatest surface of the islands. The peculiar species are rarer, the peculiar genera of continental affinity are rarer still; whilst the plants having no affinity with those of the mother continent are often very common." In a letter of March 20th, 1867, Sir Joseph explains that in the case of the Atlantic islands it is the "peculiar genera of EUROPEAN AFFINITY that are so rare," while Clethra, Dracaena and the Laurels, which have no European affinity, are common.) Etty (379/2. Mr. Darwin's daughter, now Mrs. Litchfield.), who has read your paper with great interest, was confounded by this sentence. By the way, I have stumbled on two old notes: one, that twenty-two species of European birds occasionally arrive as chance wanderers to the Azores; and, secondly, that trunks of American trees have been known to be washed on the shores of the Canary Islands by the Gulf-stream, which returns southward from the Azores. What poor papers those of A. Murray are in "Gardeners' Chronicle." What conclusions he draws from a single Carabus (379/3. "Dr. Hooker on Insular Floras" ("Gardeners' Chronicle," 1867, pages 152, 181). The reference to the Carabidous beetle (Aplothorax) is at page 181.), and that a widely ranging genus! He seems to me conceited; you and I are fair game geologically, but he refers to Lyell, as if his opinion on a geological point was worth no more than his own. I have just bought, but not read a sentence of, Murray's big book (379/4. "Geographical Distribution of Mammals," 1866.), second-hand, for 30s., new, so I do not envy the publishers. It is clear to me that the man cannot reason. I have had a very nice letter from Scott at Calcutta (379/5. See Letter 150.): he has been making some good observations on the acclimatisation of seeds from plants of same species, grown in different countries, and likewise on how far European plants will stand the climate of Calcutta. He says he is astonished how well some flourish, and he maintains, if the land were unoccupied, several could easily cross, spreading by seed, the Tropics from north to south, so he knows how to please me; but I have told him to be cautious, else he will have dragons down on him... As the Azores are only about two-and-a-half times more distant from America (in the same latitude) than from Europe, on the occasional migration view (especially as oceanic currents come directly from West Indies and Florida, and heavy gales of wind blow from the same direction), a large percentage of the flora ought to be American; as it is, we have only the Sanicula, and at present we have no explanation of this apparent anomaly, or only a feeble indication of an explanation in the birds of the Azores being all European. LETTER 380. TO J.D. HOOKER. Down, March 21st [1867]. Many thanks for your pleasant and very amusing letter. You have been treated shamefully by Etty and me, but now that I know the facts, the sentence seems to me quite clear. Nevertheless, as we have both blundered, it would be well to modify the sentence something as follows: "whilst, on the other hand, the plants which are related to those of distant continents, but have no affinity with those of the mother continent, are often very common." I forget whether you explain this circumstance, but it seems to me very mysterious (380/1. Sir Joseph Hooker wrote (March 23rd, 1867): "I see you 'smell a rat' in the matter of insular plants that are related to those of [a] distant continent being common. Yes, my beloved friend, let me make a clean breast of it. I only found it out after the lecture was in print!...I have been waiting ever since to 'think it out,' and write to you about it, coherently. I thought it best to squeeze it in, anyhow or anywhere, rather than leave so curious a fact unnoticed.")...Do always remember that nothing in the world gives us so much pleasure as seeing you here whenever you can come. I chuckle over what you say of And. Murray, but I must grapple with his book some day. LETTER 381. TO C. LYELL. Down, October 31st [1867]. Mr. [J.P. Mansel] Weale sent to me from Natal a small packet of dry locust dung, under 1/2 oz., with the statement that it is believed that they introduce new plants into a district. (381/1. See Volume I., Letter 221.) This statement, however, must be very doubtful. From this packet seven plants have germinated, belonging to at least two kinds of grasses. There is no error, for I dissected some of the seeds out of the middle of the pellets. It deserves notice that locusts are sometimes blown far out to sea. I caught one 370 miles from Africa, and I have heard of much greater distances. You might like to hear the following case, as it relates to a migratory bird belonging to the most wandering of all orders--viz. the woodcock. (381/2. "Origin," Edition VI., page 328.) The tarsus was firmly coated with mud, weighing when dry 9 grains, and from this the Juncus bufonius, or toad rush, germinated. By the way, the locust case verifies what I said in the "Origin," that many possible means of distribution would be hereafter discovered. I quite agree about the extreme difficulty of the distribution of land mollusca. You will have seen in the last edition of "Origin" (381/3. "Origin," Edition IV., page 429. The reference is to MM. Marten's (381/4. For Marten's read Martins' [the name is wrongly spelt in the "Origin of Species."]) experiments on seeds "in a box in the actual sea.") that my observations on the effects of sea-water have been confirmed. I still suspect that the legs of birds which roost on the ground may be an efficient means; but I was interrupted when going to make trials on this subject, and have never resumed it. We shall be in London in the middle of latter part of November, when I shall much enjoy seeing you. Emma sends her love, and many thanks for Lady Lyell's note. LETTER 382. TO J.D. HOOKER. Down, Wednesday [1867]. I daresay there is a great deal of truth in your remarks on the glacial affair, but we are in a muddle, and shall never agree. I am bigoted to the last inch, and will not yield. I cannot think how you can attach so much weight to the physicists, seeing how Hopkins, Hennessey, Haughton, and Thomson have enormously disagreed about the rate of cooling of the crust; remembering Herschel's speculations about cold space (382/1. The reader will find some account of Herschel's views in Lyell's "Principles," 1872, Edition XI., Volume I., page 283.), and bearing in mind all the recent speculations on change of axis, I will maintain to the death that your case of Fernando Po and Abyssinia is worth ten times more than the belief of a dozen physicists. (382/2. See "Origin," Edition VI., page 337: "Dr. Hooker has also lately shown that several of the plants living on the upper parts of the lofty island of Fernando Po and on the neighbouring Cameroon mountains, in the Gulf of Guinea, are closely related to those in the mountains of Abyssinia, and likewise to those of temperate Europe." Darwin evidently means that such facts as these are better evidence of the gigantic periods of time occupied by evolutionary changes than the discordant conclusions of the physicists. See "Linn. Soc. Journ." Volume VII., page 180, for Hooker's general conclusions; also Hooker and Ball's "Marocco," Appendix F, page 421. For the case of Fernando Po see Hooker ("Linn. Soc. Journ." VI., 1861, page 3, where he sums up: "Hence the result of comparing Clarence Peak flora [Fernando Po] with that of the African continent is--(1) the intimate relationship with Abyssinia, of whose flora it is a member, and from which it is separated by 1800 miles of absolutely unexplored country; (2) the curious relationship with the East African islands, which are still farther off; (3) the almost total dissimilarity from the Cape flora." For Sir J.D. Hooker's general conclusions on the Cameroon plants see "Linn. Soc. Journ." VII., page 180. More recently equally striking cases have come to light: for instance, the existence of a Mediterranean genus, Adenocarpus, in the Cameroons and on Kilima Njaro, and nowhere else in Africa; and the probable migration of South African forms along the highlands from the Natal District to Abysinnia. See Hooker, "Linn. Soc. Journ." XIV., 1874, pages 144-5.) Your remarks on my regarding temperate plants and disregarding the tropical plants made me at first uncomfortable, but I soon recovered. You say that all botanists would agree that many tropical plants could not withstand a somewhat cooler climate. But I have come not to care at all for general beliefs without the special facts. I have suffered too often from this: thus I found in every book the general statement that a host of flowers were fertilised in the bud, that seeds could not withstand salt water, etc., etc. I would far more trust such graphic accounts as that by you of the mixed vegetation on the Himalayas and other such accounts. And with respect to tropical plants withstanding the slowly coming on cool period, I trust to such facts as yours (and others) about seeds of the same species from mountains and plains having acquired a slightly different climatal constitution. I know all that I have said will excite in you savage contempt towards me. Do not answer this rigmarole, but attack me to your heart's content, and to that of mine, whenever you can come here, and may it be soon. LETTER 383. J.D. HOOKER TO CHARLES DARWIN. Kew, 1870. (383/1. The following extract from a letter of Sir J.D. Hooker shows the tables reversed between the correspondents.) Grove is disgusted at your being disquieted about W. Thomson. Tell George from me not to sit upon you with his mathematics. When I threatened your tropical cooling views with the facts of the physicists, you snubbed me and the facts sweetly, over and over again; and now, because a scarecrow of x+y has been raised on the selfsame facts, you boo-boo. Take another dose of Huxley's penultimate G. S. Address, and send George back to college. (383/2. Huxley's Anniversary Address to the Geological Society, 1869 ("Collected Essays," VIII., page 305). This is a criticism of Lord Kelvin's paper "On Geological Time" ("Trans. Geolog. Soc. Glasgow," III.). At page 336 Mr. Huxley deals with Lord Kelvin's "third line of argument, based on the temperature of the interior of the earth." This was no doubt the point most disturbing to Mr. Darwin, since it led Lord Kelvin to ask (as quoted by Huxley), "Are modern geologists prepared to say that all life was killed off the earth 50,000, 100,000, or 200,000 years ago?" Mr. Huxley, after criticising Lord Kelvin's data and conclusion, gives his conviction that the case against Geology has broken down. With regard to evolution, Huxley (page 328) ingeniously points out a case of circular reasoning. "But it may be said that it is biology, and not geology, which asks for so much time--that the succession of life demands vast intervals; but this appears to me to be reasoning in a circle. Biology takes her time from geology. The only reason we have for believing in the slow rate of the change in living forms is the fact that they persist through a series of deposits which, geology informs us, have taken a long while to make. If the geological clock is wrong, all the naturalist will have to do is to modify his notions of the rapidity of change accordingly.") LETTER 384. TO J.D. HOOKER. February 3rd [1868]. I am now reading Miquel on "Flora of Japan" (384/1. Miquel, "Flore du Japon": "Archives Neerlandaises" ii., 1867.), and like it: it is rather a relief to me (though, of course, not new to you) to find so very much in common with Asia. I wonder if A. Murray's (384/2. "Geographical Distribution of Mammals," by Andrew Murray, 1866. See Chapter V., page 47. See Letter 379.) notion can be correct, that a [profound] arm of the sea penetrated the west coast of N. America, and prevented the Asiatico-Japan element colonising that side of the continent so much as the eastern side; or will climate suffice? I shall to the day of my death keep up my full interest in Geographical Distribution, but I doubt whether I shall ever have strength to come in any fuller detail than in the "Origin" to this grand subject. In fact, I do not suppose any man could master so comprehensive a subject as it now has become, if all kingdoms of nature are included. I have read Murray's book, and am disappointed--though, as you said, here and there clever thoughts occur. How strange it is, that his view not affording the least explanation of the innumerable adaptations everywhere to be seen apparently does not in the least trouble his mind. One of the most curious cases which he adduces seems to me to be the two allied fresh-water, highly peculiar porpoises in the Ganges and Indus; and the more distantly allied form of the Amazons. Do you remember his explanation of an arm of the sea becoming cut off, like the Caspian, converted into fresh-water, and then divided into two lakes (by upheaval), giving rise to two great rivers. But no light is thus thrown on the affinity of the Amazon form. I now find from Flower's paper (384/3. "Zoolog. Trans." VI., 1869, page 115. The toothed whales are divided into the Physeteridae, the Delphinidae, and the Platanistidae, which latter is placed between the two other families, and is divided into the sub-families Iniinae and Platanistinae.) that these fresh-water porpoises form two sub-families, making an extremely isolated and intermediate, very small family. Hence to us they are clearly remnants of a large group; and I cannot doubt we here have a good instance precisely like that of ganoid fishes, of a large ancient marine group, preserved exclusively in fresh-water, where there has been less competition, and consequently little modification. (384/4. See Volume I., Letter 95.) What a grand fact that is which Miquel gives of the beech not extending beyond the Caucasus, and then reappearing in Japan, like your Himalayan Pinus, and the cedar of Lebanon. (384/5. For Pinus read Deodar. The essential identity of the deodar and the cedar of Lebanon was pointed out in Hooker's "Himalayan Journals" in 1854 (Volume I., page 257.n). In the "Nat. History Review," January, 1862, the question is more fully dealt with by him, and the distribution discussed. The nearest point at which cedars occur is the Bulgar-dagh chain of Taurus--250 miles from Lebanon. Under the name of Cedrus atlantica the tree occurs in mass on the borders of Tunis, and as Deodar it first appears to the east in the cedar forests of Afghanistan. Sir J.D. Hooker supposes that, during a period of greater cold, the cedars on the Taurus and on Lebanon lived many thousand feet nearer the sea-level, and spread much farther to the east, meeting similar belts of trees descending and spreading westward from Afghanistan along the Persian mountains.) I know of nothing that gives one such an idea of the recent mutations in the surface of the land as these living "outlyers." In the geological sense we must, I suppose, admit that every yard of land has been successively covered with a beech forest between the Caucasus and Japan! I have not yet seen (for I have not sent to the station) Falconer's works. When you say that you sigh to think how poor your reprinted memoirs would appear, on my soul I should like to shake you till your bones rattled for talking such nonsense. Do you sigh over the "Insular Floras," the Introduction to New Zealand Flora, to Australia, your Arctic Flora, and dear Galapagos, etc., etc., etc.? In imagination I am grinding my teeth and choking you till I put sense into you. Farewell. I have amused myself by writing an audaciously long letter. By the way, we heard yesterday that George has won the second Smith's Prize, which I am excessively glad of, as the Second Wrangler by no means always succeeds. The examination consists exclusively of [the] most difficult subjects, which such men as Stokes, Cayley, and Adams can set. LETTER 385. A.R. WALLACE TO CHARLES DARWIN. March 8th, 1868. ...While writing a few pages on the northern alpine forms of plants on the Java mountains I wanted a few cases to refer to like Teneriffe, where there are no northern forms and scarcely any alpine. I expected the volcanoes of Hawaii would be a good case, and asked Dr. Seemann about them. It seems a man has lately published a list of Hawaiian plants, and the mountains swarm with European alpine genera and some species! (385/1. "This turns out to be inaccurate, or greatly exaggerated. There are no true alpines, and the European genera are comparatively few. See my 'Island Life,' page 323."--A.R.W.) Is not this most extraordinary, and a puzzler? They are, I believe, truly oceanic islands, in the absence of mammals and the extreme poverty of birds and insects, and they are within the Tropics. Will not that be a hard nut for you when you come to treat in detail on geographical distribution? I enclose Seemann's note, which please return when you have copied the list, if of any use to you. LETTER 386. TO J.D. HOOKER. Down, February 21st [1870]. I read yesterday the notes on Round Island (386/1. In Wallace's "Island Life," page 410, Round Island is described as an islet "only about a mile across, and situated about fourteen miles north-east of Mauritius." Wallace mentions a snake, a python belonging to the peculiar and distinct genus Casarea, as found on Round Island, and nowhere else in the world. The palm Latania Loddigesii is quoted by Wallace as "confined to Round Island and two other adjacent islets." See Baker's "Flora of the Mauritius and the Seychelles." Mr. Wallace says that, judging from the soundings, Round Island was connected with Mauritius, and that when it was "first separated [it] would have been both much larger and much nearer the main island.") which I owe to you. Was there ever such an enigma? If, in the course of a week or two, you can find time to let me hear what you think, I should very much like to hear: or we hope to be at Erasmus' on March 4th for a week. Would there be any chance of your coming to luncheon then? What a case it is. Palms, screw-pines, four snakes--not one being in main island--lizards, insects, and not one land bird. But, above everything, such a proportion of individual monocotyledons! The conditions do not seem very different from the Tuff Galapagos Island, but, as far as I remember, very few monocotyledons there. Then, again, the island seems to have been elevated. I wonder much whether it stands out in the line of any oceanic current, which does not so forcibly strike the main island? But why, oh, why should so many monocotyledons have come there? or why should they have survived there more than on the main island, if once connected? So, again, I cannot conceive that four snakes should have become extinct in Mauritius and survived on Round Island. For a moment I thought that Mauritius might be the newer island, but the enormous degradation which the outer ring of rocks has undergone flatly contradicts this, and the marine remains on the summit of Round Island indicate the island to be comparatively new--unless, indeed, they are fossil and extinct marine remains. Do tell me what you think. There never was such an enigma. I rather lean to separate immigration, with, of course, subsequent modification; some forms, of course, also coming from Mauritius. Speaking of Mauritius reminds me that I was so much pleased the day before yesterday by reading a review of a book on the geology of St. Helena, by an officer who knew nothing of my hurried observations, but confirms nearly all that I have said on the general structure of the island, and on its marvellous denudation. The geology of that island was like a novel. LETTER 387. TO A. BLYTT. Down, March 28th, 1876. (387/1. The following refers to Blytt's "Essay on the Immigration of the Norwegian Flora during Alternating Rainy and Dry Periods," Christiania, 1876.) I thank you sincerely for your kindness in having sent me your work on the "Immigration of the Norwegian Flora," which has interested me in the highest degree. Your view, supported as it is by various facts, appears to me the most important contribution towards understanding the present distribution of plants, which has appeared since Forbes' essay on the effects of the Glacial Period. LETTER 388. TO AUG. FOREL. Down, June 19th, 1876. I hope you will allow me to suggest an observation, should any opportunity occur, on a point which has interested me for many years--viz., how do the coleoptera which inhabit the nests of ants colonise a new nest? Mr. Wallace, in reference to the presence of such coleoptera in Madeira, suggests that their ova may be attached to the winged female ants, and that these are occasionally blown across the ocean to the island. It would be very interesting to discover whether the ova are adhesive, and whether the female coleoptera are guided by instinct to attach them to the female ants (388/1. Dr. Sharp is good enough to tell us that he is not aware of any such adaptation. Broadly speaking, the distribution of the nest-inhabiting beetles is due to co-migration with the ants, though in some cases the ants transport the beetles. Sitaris and Meloe are beetles which live "at the expense of bees of the genus Anthophora." The eggs are laid not in but near the bees' nest; in the early stage the larva is active and has the instinct to seize any hairy object near it, and in this way they are carried by the Anthophora to the nest. Dr. Sharp states that no such preliminary stage is known in the ant's-nest beetles. For an account of Sitaris and Meloe, see Sharp's "Insects," II., page 272.); or whether the larvae pass through an early stage, as with Sitaris or Meloe, or cling to the bodies of the females. This note obviously requires no answer. I trust that you continue your most interesting investigations on ants. (PLATE: MR. A.R. WALLACE, 1878. From a photograph by Maull & Fox.) LETTER 389. TO A.R. WALLACE. (389/1. Published in "Life and Letters," III., page 230.) (389/2. The following five letters refer to Mr. Wallace's "Geographical Distribution of Animals," 1876.) [Hopedene] (389/3. Mr. Hensleigh Wedgwood's house in Surrey.), June 5th, 1876. I must have the pleasure of expressing to you my unbounded admiration of your book (389/4. "Geographical Distribution," 1876.), though I have read only to page 184--my object having been to do as little as possible while resting. I feel sure that you have laid a broad and safe foundation for all future work on Distribution. How interesting it will be to see hereafter plants treated in strict relation to your views; and then all insects, pulmonate molluscs and fresh-water fishes, in greater detail than I suppose you have given to these lower animals. The point which has interested me most, but I do not say the most valuable point, is your protest against sinking imaginary continents in a quite reckless manner, as was stated by Forbes, followed, alas, by Hooker, and caricatured by Wollaston and [Andrew] Murray! By the way, the main impression that the latter author has left on my mind is his utter want of all scientific judgment. I have lifted up my voice against the above view with no avail, but I have no doubt that you will succeed, owing to your new arguments and the coloured chart. Of a special value, as it seems to me, is the conclusion that we must determine the areas, chiefly by the nature of the mammals. When I worked many years ago on this subject, I doubted much whether the now-called Palaearctic and Nearctic regions ought to be separated; and I determined if I made another region that it should be Madagascar. I have, therefore, been able to appreciate your evidence on these points. What progress Palaeontology has made during the last twenty years! but if it advances at the same rate in the future, our views on the migration and birthplace of the various groups will, I fear, be greatly altered. I cannot feel quite easy about the Glacial period, and the extinction of large mammals, but I must hope that you are right. I think you will have to modify your belief about the difficulty of dispersal of land molluscs; I was interrupted when beginning to experimentise on the just hatched young adhering to the feet of ground-roosting birds. I differ on one other point--viz. in the belief that there must have existed a Tertiary Antarctic continent, from which various forms radiated to the southern extremities of our present continents. But I could go on scribbling forever. You have written, as I believe, a grand and memorable work, which will last for years as the foundation for all future treatises on Geographical Distribution. P.S.--You have paid me the highest conceivable compliment, by what you say of your work in relation to my chapters on distribution in the "Origin," and I heartily thank you for it. LETTER 390. FROM A.R. WALLACE TO CHARLES DARWIN. The Dell, Grays, Essex, June 7th, 1876. Many thanks for your very kind letter. So few people will read my book at all regularly, that a criticism from one who does so will be very welcome. If, as I suppose, it is only to page 184 of Volume I. that you have read, you cannot yet quite see my conclusions on the points you refer to (land molluscs and Antarctic continent). My own conclusion fluctuated during the progress of the book, and I have, I know, occasionally used expressions (the relics of earlier ideas) which are not quite consistent with what I say further on. I am positively against any Southern continent as uniting South America with Australia or New Zealand, as you will see at Volume I., pages 398-403, and 459-66. My general conclusions as to distribution of land mollusca are at Volume II., pages 522-9. (390/1. "Geographical Distribution" II., pages 524, 525. Mr. Wallace points out that "hardly a small island on the globe but has some land-shells peculiar to it"--and he goes so far as to say that probably air-breathing mollusca have been chiefly distributed by air- or water-carriage, rather than by voluntary dispersal on the land.) When you have read these passages, and looked at the general facts which lead to them, I shall be glad to hear if you still differ from me. Though, of course, present results as to the origin and migrations of genera of mammals will have to be modified owing to new discoveries, I cannot help thinking that much will remain unaffected, because in all geographical and geological discoveries the great outlines are soon reached, the details alone remain to be modified. I also think much of the geological evidence is now so accordant with, and explanatory of, Geographical Distribution, that it is prima facie correct in outline. Nevertheless, such vast masses of new facts will come out in the next few years that I quite dread the labour of incorporating them in a new edition. I hope your health is improved; and when, quite at your leisure, you have waded through my book, I trust you will again let me have a few lines of friendly criticism and advice. LETTER 391. TO A.R. WALLACE. Down, June 17th, 1876. I have now finished the whole of Volume I., with the same interest and admiration as before; and I am convinced that my judgment was right and that it is a memorable book, the basis of all future work on the subject. I have nothing particular to say, but perhaps you would like to hear my impressions on two or three points. Nothing has struck me more than the admirable and convincing manner in which you treat Java. To allude to a very trifling point, it is capital about the unadorned head of the Argus-pheasant. (391/1. See "Descent of Man," Edition I., pages 90 and 143, for drawings of the Argus pheasant and its markings. The ocelli on the wing feathers were favourite objects of Mr. Darwin, and sometimes formed the subject of the little lectures which on rare occasions he would give to a visitor interested in Natural History. In Mr. Wallace's book the meaning of the ocelli comes in by the way, in the explanation of Plate IX., "A Malayan Forest with some of its peculiar Birds." Mr. Wallace (volume i., page 340) points out that the head of the Argus pheasant is, during the display of the wings, concealed from the view of a spectator in front, and this accounts for the absence of bright colour on the head--a most unusual point in a pheasant. The case is described as a "remarkable confirmation of Mr. Darwin's views, that gaily coloured plumes are developed in the male bird for the purpose of attractive display." For the difference of opinion between the two naturalists on the broad question of coloration see "Life and Letters," III., page 123. See Letters 440-453.) How plain a thing is, when it is once pointed out! What a wonderful case is that of Celebes: I am glad that you have slightly modified your views with respect to Africa. (391/2. "I think this must refer to the following passage in 'Geog. Dist. of Animals,' Volume I., pages 286-7. 'At this period (Miocene) Madagascar was no doubt united with Africa, and helped to form a great southern continent which must at one time have extended eastward as far as Southern India and Ceylon; and over the whole of this the lemurine type no doubt prevailed.' At the time this was written I had not paid so much attention to islands, and in my "Island Life" I have given ample reasons for my belief that the evidence of extinct animals does not require any direct connection between Southern India and Africa."--Note by Mr. Wallace.) And this leads me to say that I cannot swallow the so-called continent of Lemuria--i.e., the direct connection of Africa and Ceylon. (391/3. See "Geographical Distribution," I., page 76. The name Lemuria was proposed by Mr. Sclater for an imaginary submerged continent extending from Madagascar to Ceylon and Sumatra. Mr. Wallace points out that if we confine ourselves to facts Lemuria is reduced to Madagascar, which he makes a subdivision of the Ethiopian Region.) The facts do not seem to me many and strong enough to justify so immense a change of level. Moreover, Mauritius and the other islands appear to me oceanic in character. But do not suppose that I place my judgment on this subject on a level with yours. A wonderfully good paper was published about a year ago on India, in the "Geological Journal," I think by Blanford. (391/4. H.F. Blanford "On the Age and Correlations of the Plant-bearing Series of India and the Former Existence of an Indo-Oceanic Continent" ("Quart. Journ. Geol. Soc." XXXI., 1875, page 519). The name Gondwana-Land was subsequently suggested by Professor Suess for this Indo-Oceanic continent. Since the publication of Blanford's paper, much literature has appeared dealing with the evidence furnished by fossil plants, etc., in favour of the existence of a vast southern continent.) Ramsay agreed with me that it was one of the best published for a long time. The author shows that India has been a continent with enormous fresh-water lakes, from the Permian period to the present day. If I remember right, he believes in a former connection with S. Africa. I am sure that I read, some twenty to thirty years ago in a French journal, an account of teeth of Mastodon found in Timor; but the statement may have been an error. (391/5. In a letter to Falconer (Letter 155), January 5th, 1863, Darwin refers to the supposed occurrence of Mastodon as having been "smashed" by Falconer.) With respect to what you say about the colonising of New Zealand, I somewhere have an account of a frog frozen in the ice of a Swiss glacier, and which revived when thawed. I may add that there is an Indian toad which can resist salt-water and haunts the seaside. Nothing ever astonished me more than the case of the Galaxias; but it does not seem known whether it may not be a migratory fish like the salmon. (391/6. The only genus of the Galaxidae, a family of fresh-water fishes occurring in New Zealand, Tasmania, and Tierra del Fuego, ranging north as far as Queensland and Chile (Wallace's "Geographical Distribution," II., page 448).) LETTER 392. TO A.R. WALLACE. Down, June 25th, 1876. I have been able to read rather more quickly of late, and have finished your book. I have not much to say. Your careful account of the temperate parts of South America interested me much, and all the more from knowing something of the country. I like also much the general remarks towards the end of the volume on the land molluscs. Now for a few criticisms. Page 122. (392/1. The pages refer to Volume II. of Wallace's "Geographical Distribution.")--I am surprised at your saying that "during the whole Tertiary period North America was zoologically far more strongly contrasted with South America than it is now." But we know hardly anything of the latter except during the Pliocene period; and then the mastodon, horse, several great edentata, etc., etc., were common to the north and south. If you are right, I erred greatly in my "Journal," where I insisted on the former close connection between the two. Page 252 and elsewhere.--I agree thoroughly with the general principle that a great area with many competing forms is necessary for much and high development; but do you not extend this principle too far--I should say much too far, considering how often several species of the same genus have been developed on very small islands? Page 265.--You say that the Sittidae extend to Madagascar, but there is no number in the tabular heading. [The number (4) was erroneously omitted.--A.R.W.] Page 359.--Rhinochetus is entered in the tabular heading under No. 3 of the neotropical subregions. [An error: should have been the Australian.--A.R.W.] Reviewers think it necessary to find some fault; and if I were to review you, the sole point which I should blame is your not giving very numerous references. These would save whoever follows you great labour. Occasionally I wished myself to know the authority for certain statements, and whether you or somebody else had originated certain subordinate views. Take the case of a man who had collected largely on some island, for instance St. Helena, and who wished to work out the geographical relations of his collections: he would, I think, feel very blank at not finding in your work precise references to all that had been written on St. Helena. I hope you will not think me a confoundedly disagreeable fellow. I may mention a capital essay which I received a few months ago from Axel Blytt (392/2. Axel Blytt, "Essay on the Immigration of the Norwegian Flora." Christiania, 1876. See Letter 387.) on the distribution of the plants of Scandinavia; showing the high probability of there having been secular periods alternately wet and dry, and of the important part which they have played in distribution. I wrote to Forel (392/3. See Letter 388.), who is always at work on ants, and told him your views about the dispersal of the blind coleoptera, and asked him to observe. I spoke to Hooker about your book, and feel sure that he would like nothing better than to consider the distribution of plants in relation to your views; but he seemed to doubt whether he should ever have time. And now I have done my jottings, and once again congratulate you on having brought out so grand a work. I have been a little disappointed at the review in "Nature." (392/4. June 22nd, 1876, pages 165 et seq.) LETTER 393. A.R. WALLACE TO CHARLES DARWIN. Rosehill, Dorking, July 23rd, 1876. I should have replied sooner to your last kind and interesting letters, but they reached me in the midst of my packing previous to removal here, and I have only just now got my books and papers in a get-at-able state. And first, many thanks for your close observation in detecting the two absurd mistakes in the tabular headings. As to the former greater distinction of the North and South American faunas, I think I am right. The edentata being proved (as I hold) to have been mere temporary migrants into North America in the post-Pliocene epoch, form no part of its Tertiary fauna. Yet in South America they were so enormously developed in the Pliocene epoch that we know, if there is any such thing as evolution, etc., that strange ancestral forms must have preceded them in Miocene times. Mastodon, on the other hand, represented by one or two species only, appears to have been a late immigrant into South America from the north. The immense development of ungulates (in varied families, genera, and species) in North America during the whole Tertiary epoch is, however, the great feature which assimilates it to Europe, and contrasts it with South America. True camels, hosts of hog-like animals, true rhinoceroses, and hosts of ancestral horses, all bring the North American [fauna] much nearer to the Old World than it is now. Even the horse, represented in all South America by Equus only, was probably a temporary immigrant from the north. As to extending too far the principle (yours) of the necessity of comparatively large areas for the development of varied faunas, I may have done so, but I think not. There is, I think, every probability that most islands, etc., where a varied fauna now exists, have been once more extensive--eg., New Zealand, Madagascar: where there is no such evidence (e.g., Galapagos), the fauna is very restricted. Lastly, as to want of references: I confess the justice of your criticism; but I am dreadfully unsystematic. It is my first large work involving much of the labour of others. I began with the intention of writing a comparatively short sketch, enlarged it, and added to it bit by bit; remodelled the tables, the headings, and almost everything else, more than once, and got my materials in such confusion that it is a wonder it has not turned out far more crooked and confused than it is. I, no doubt, ought to have given references; but in many cases I found the information so small and scattered, and so much had to be combined and condensed from conflicting authorities, that I hardly knew how to refer to them or where to leave off. Had I referred to all authors consulted for every fact, I should have greatly increased the bulk of the book, while a large portion of the references would be valueless in a few years, owing to later and better authorities. My experience of referring to references has generally been most unsatisfactory. One finds, nine times out of ten, the fact is stated, and nothing more; or a reference to some third work not at hand! I wish I could get into the habit of giving chapter and verse for every fact and extract; but I am too lazy, and generally in a hurry, having to consult books against time, when in London for a day. However, I will try to do something to mend this matter, should I have to prepare another edition. I return you Forel's letter. It does not advance the question much; neither do I think it likely that even the complete observation he thinks necessary would be of much use, because it may well be that the ova, or larvae, or imagos of the beetles are not carried systematically by the ants, but only occasionally, owing to some exceptional circumstances. This might produce a great effect in distribution, yet be so rare as never to come under observation. Several of your remarks in previous letters I shall carefully consider. I know that, compared with the extent of the subject, my book is in many parts crude and ill-considered; but I thought, and still think, it better to make some generalisations wherever possible, as I am not at all afraid of having to alter my views in many points of detail. I was so overwhelmed with zoological details, that I never went through the Geological Society's "Journal" as I ought to have done, and as I mean to do before writing more on the subject. LETTER 394. TO F. BUCHANAN WHITE. (394/1. "Written in acknowledgment of a copy of a paper (published by me in the "Proceedings of the Zoological Society") on the Hemiptera of St. Helena, but discussing the origin of the whole fauna and flora of that island."--F.B.W.) Down, September 23rd. [1878]. I have now read your paper, and I hope that you will not think me presumptuous in writing another line to say how excellent it seems to me. I believe that you have largely solved the problem of the affinities of the inhabitants of this most interesting little island, and this is a delightful triumph. LETTER 395. TO J.D. HOOKER. Down, July 22nd [1879]. I have just read Ball's Essay. (395/1. The late John Ball's lecture "On the Origin of the Flora of the Alps" in the "Proceedings of the R. Geogr. Soc." 1879. Ball argues (page 18) that "during ancient Palaeozoic times, before the deposition of the Coal-measures, the atmosphere contained twenty times as much carbonic acid gas and considerably less oxygen than it does at present." He further assumes that in such an atmosphere the percentage of CO2 in the higher mountains would be excessively different from that at the sea-level, and appends the result of calculations which gives the amount of CO2 at the sea-level as 100 per 10,000 by weight, at a height of 10,000 feet as 12.5 per 10,000. Darwin understands him to mean that the Vascular Cryptogams and Gymnosperms could stand the sea-level atmosphere, whereas the Angiosperms would only be able to exist in the higher regions where the percentage of CO2 was small. It is not clear to us that Ball relies so largely on the condition of the atmosphere as regards CO2. If he does he is clearly in error, for everything we know of assimilation points to the conclusion that 100 per 10,000 (1 per cent.) is by no means a hurtful amount of CO2, and that it would lead to an especially vigorous assimilation. Mountain plants would be more likely to descend to the plains to share in the rich feast than ascend to higher regions to avoid it. Ball draws attention to the imperfection of our plant records as regards the floras of mountain regions. It is, he thinks, conceivable that there existed a vegetation on the Carboniferous mountains of which no traces have been preserved in the rocks. See "Fossil Plants as Tests of Climate," page 40, A.C. Seward, 1892. Since the first part of this note was written, a paper has been read (May 29th, 1902) by Dr. H.T. Brown and Mr. F. Escombe, before the Royal Society on "The Influence of varying amounts of Carbon Dioxide in the Air on the Photosynthetic Process of Leaves, and on the Mode of Growth of Plants." The author's experiments included the cultivation of several dicotyledonous plants in an atmosphere containing in one case 180 to 200 times the normal amount of CO2, and in another between three and four times the normal amount. The general results were practically identical in the two sets of experiments. "All the species of flowering plants, which have been the subject of experiment, appear to be accurately 'tuned' to an atmospheric environment of three parts of CO2 per 10,000, and the response which they make to slight increases in this amount are in a direction altogether unfavourable to their growth and reproduction." The assimilation of carbon increases with the increase in the partial pressure of the CO2. But there seems to be a disturbance in metabolism, and the plants fail to take advantage of the increased supply of CO2. The authors say:--"All we are justified in concluding is, that if such atmospheric variations have occurred since the advent of flowering plants, they must have taken place so slowly as never to outrun the possible adaptation of the plants to their changing conditions." Prof. Farmer and Mr. S.E. Chandler gave an account, at the same meeting of the Royal Society, of their work "On the Influence of an Excess of Carbon Dioxide in the Air on the Form and Internal Structure of Plants." The results obtained were described as differing in a remarkable way from those previously recorded by Teodoresco ("Rev. Gen. Botanique," II., 1899 It is hoped that Dr. Horace Brown and Mr. Escombe will extend their experiments to Vascular Cryptogams, and thus obtain evidence bearing more directly upon the question of an increased amount of CO2 in the atmosphere of the Coal-period forests.) It is pretty bold. The rapid development as far as we can judge of all the higher plants within recent geological times is an abominable mystery. Certainly it would be a great step if we could believe that the higher plants at first could live only at a high level; but until it is experimentally [proved] that Cycadeae, ferns, etc., can withstand much more carbonic acid than the higher plants, the hypothesis seems to me far too rash. Saporta believes that there was an astonishingly rapid development of the high plants, as soon [as] flower-frequenting insects were developed and favoured intercrossing. I should like to see this whole problem solved. I have fancied that perhaps there was during long ages a small isolated continent in the S. Hemisphere which served as the birthplace of the higher plants--but this is a wretchedly poor conjecture. It is odd that Ball does not allude to the obvious fact that there must have been alpine plants before the Glacial period, many of which would have returned to the mountains after the Glacial period, when the climate again became warm. I always accounted to myself in this manner for the gentians, etc. Ball ought also to have considered the alpine insects common to the Arctic regions. I do not know how it may be with you, but my faith in the glacial migration is not at all shaken. LETTER 396. A.R. WALLACE TO CHARLES DARWIN. (396/1. This letter is in reply to Mr. Darwin's criticisms on Mr. Wallace's "Island Life," 1880.) Pen-y-Bryn, St. Peter's Road, Croydon, November 8th, 1880. Many thanks for your kind remarks and notes on my book. Several of the latter will be of use to me if I have to prepare a second edition, which I am not so sure of as you seem to be. 1. In your remark as to the doubtfulness of paucity of fossils being due to coldness of water, I think you overlook that I am speaking only of water in the latitude of the Alps, in Miocene and Eocene times, when icebergs and glaciers temporarily descended into an otherwise warm sea; my theory being that there was no Glacial epoch at that time, but merely a local and temporary descent of the snow-line and glaciers owing to high excentricity and winter in aphelion. 2. I cannot see the difficulty about the cessation of the Glacial period. Between the Miocene and the Pleistocene periods geographical changes occurred which rendered a true Glacial period possible with high excentricity. When the high excentricity passed away the Glacial epoch also passed away in the temperate zone; but it persists in the arctic zone, where, during the Miocene, there were mild climates, and this is due to the persistence of the changed geographical conditions. The present arctic climate is itself a comparatively new and abnormal state of things, due to geographical modification. As to "epoch" and "period," I use them as synonyms to avoid repeating the same word. 3. Rate of deposition and geological time. Here no doubt I may have gone to an extreme, but my "28 million years" may be anything under 100 millions, as I state. There is an enormous difference between mean and maximum denudation and deposition. In the case of the great faults the upheaval along a given line would itself facilitate the denudation (whether sub-aerial or marine) of the upheaved portion at a rate perhaps a hundred times above the average, just as valleys have been denuded perhaps a hundred times faster than plains and plateaux. So local subsidence might itself lead to very rapid deposition. Suppose a portion of the Gulf of Mexico, near the mouths of the Mississippi, were to subside for a few thousand years, it might receive the greater portion of the sediment from the whole Mississippi valley, and thus form strata at a very rapid rate. 4. You quote the Pampas thistles, etc., against my statement of the importance of preoccupation. But I am referring especially to St. Helena, and to plants naturally introduced from the adjacent continents. Surely if a certain number of African plants reached the island, and became modified into a complete adaptation to its climatic conditions, they would hardly be expelled by other African plants arriving subsequently. They might be so, conceivably, but it does not seem probable. The cases of the Pampas, New Zealand, Tahiti, etc., are very different, where highly developed aggressive plants have been artificially introduced. Under nature it is these very aggressive species that would first reach any island in their vicinity, and, being adapted to the island and colonising it thoroughly, would then hold their own against other plants from the same country, mostly less aggressive in character. I have not explained this so fully as I should have done in the book. Your criticism is therefore useful. 5. My Chapter XXIII. is no doubt very speculative, and I cannot wonder at your hesitating at accepting my views. To me, however, your theory of hosts of existing species migrating over the tropical lowlands from the N. temperate to the S. temperate zone appears more speculative and more improbable. For where could the rich lowland equatorial flora have existed during a period of general refrigeration sufficient for this? and what became of the wonderfully rich Cape flora, which, if the temperature of tropical Africa had been so recently lowered, would certainly have spread northwards, and on the return of the heat could hardly have been driven back into the sharply defined and very restricted area in which it now exists. As to the migration of plants from mountain to mountain not being so probable as to remote islands, I think that is fully counterbalanced by two considerations:-- a. The area and abundance of the mountain stations along such a range as the Andes are immensely greater than those of the islands in the N. Atlantic, for example. b. The temporary occupation of mountain stations by migrating plants (which I think I have shown to be probable) renders time a much more important element in increasing the number and variety of the plants so dispersed than in the case of islands, where the flora soon acquires a fixed and endemic character, and where the number of species is necessarily limited. No doubt direct evidence of seeds being carried great distances through the air is wanted, but I am afraid can hardly be obtained. Yet I feel the greatest confidence that they are so carried. Take, for instance, the two peculiar orchids of the Azores (Habenaria sp.) What other mode of transit is conceivable? The whole subject is one of great difficulty, but I hope my chapter may call attention to a hitherto neglected factor in the distribution of plants. Your references to the Mauritius literature are very interesting, and will be useful to me; and I again thank you for your valuable remarks. LETTER 397. TO J.D. HOOKER. (397/1. The following letters were written to Sir J.D. Hooker when he was preparing his Address as President of the Geographical Section of the British Association at its fiftieth meeting, at York. The second letter (August 12th) refers to an earlier letter of August 6th, published in "Life and Letters," III., page 246.) 4, Bryanston Street, W., Saturday, 26th [February, 1881]. I should think that you might make a very interesting address on Geographical Distribution. Could you give a little history of the subject. I, for one, should like to read such history in petto; but I can see one very great difficulty--that you yourself ought to figure most prominently in it; and this you would not do, for you are just the man to treat yourself in a dishonourable manner. I should very much like to see you discuss some of Wallace's views, especially his ignoring the all-powerful effects of the Glacial period with respect to alpine plants. (397/2. "Having been kindly permitted by Mr. Francis Darwin to read this letter, I wish to explain that the above statement applies only to my rejection of Darwin's view that the presence of arctic and north temperate plants in the SOUTHERN HEMISPHERE was brought about by the lowering of the temperature of the tropical regions during the Glacial period, so that even 'the lowlands of these great continents were everywhere tenanted under the equator by a considerable number of temperate forms ("Origin of Species," Edition VI., page 338). My own views are fully explained in Chapter XXIII. of my "Island Life," published in 1880. I quite accept all that Darwin, Hooker, and Asa Gray have written about the effect of the Glacial epoch in bringing about the present distribution of alpine and arctic plants in the NORTHERN HEMISPHERE."--Note by Mr. Wallace.) I do not know what you think, but it appears to me that he exaggerates enormously the influence of debacles or slips and new surface of soil being exposed for the reception of wind-blown seeds. What kinds of seeds have the plants which are common to the distant mountain-summits in Africa? Wallace lately wrote to me about the mountain plants of Madagascar being the same with those on mountains in Africa, and seemed to think it proved dispersal by the wind, without apparently having inquired what sorts of seeds the plants bore. (397/3. The affinity with the flora of the Eastern African islands was long ago pointed out by Sir J.D. Hooker, "Linn. Soc. Journal," VI., 1861, page 3. Speaking of the plants of Clarence Peak in Fernando Po, he says, "The next affinity is with Mauritius, Bourbon, and Madagascar: of the whole 76 species, 16 inhabit these places and 8 more are closely allied to plants from there. Three temperate species are peculiar to Clarence Peak and the East African islands..." The facts to which Mr. Wallace called Darwin's attention are given by Mr. J.G. Baker in "Nature," December 9th, 1880, page 125. He mentions the Madagascar Viola, which occurs elsewhere only at 7,000 feet in the Cameroons, at 10,000 feet in Fernando Po and in the Abyssinian mountains; and the same thing is true of the Madagascar Geranium. In Mr. Wallace's letter to Darwin, dated January 1st, 1881, he evidently uses the expression "passing through the air" in contradistinction to the migration of a species by gradual extension of its area on land. "Through the air" would moreover include occasional modes of transport other than simple carriage by wind: e.g., the seeds might be carried by birds, either attached to the feathers or to the mud on their feet, or in their crops or intestines.) I suppose it would be travelling too far (though for the geographical section the discussion ought to be far-reaching), but I should like to see the European or northern element in the Cape of Good Hope flora discussed. I cannot swallow Wallace's view that European plants travelled down the Andes, tenanted the hypothetical Antarctic continent (in which I quite believe), and thence spread to South Australia and the Cape of Good Hope. Moseley told me not long ago that he proposed to search at Kerguelen Land the coal beds most carefully, and was absolutely forbidden to do so by Sir W. Thomson, who said that he would undertake the work, and he never once visited them. This puts me in a passion. I hope that you will keep to your intention and make an address on distribution. Though I differ so much from Wallace, his "Island Life" seems to me a wonderful book. Farewell. I do hope that you may have a most prosperous journey. Give my kindest remembrances to Asa Gray. LETTER 398. TO J.D. HOOKER. Down, August 12th, 1881. ...I think that I must have expressed myself badly about Humboldt. I should have said that he was more remarkable for his astounding knowledge than for originality. I have always looked at him as, in fact, the founder of the geographical distribution of organisms. I thought that I had read that extinct fossil plants belonging to Australian forms had lately been found in Australia, and all such cases seem to me very interesting, as bearing on development. I have been so astonished at the apparently sudden coming in of the higher phanerogams, that I have sometimes fancied that development might have slowly gone on for an immense period in some isolated continent or large island, perhaps near the South Pole. I poured out my idle thoughts in writing, as if I had been talking with you. No fact has so interested me for a heap of years as your case of the plants on the equatorial mountains of Africa; and Wallace tells me that some one (Baker?) has described analogous cases on the mountains of Madagascar (398/1. See Letter 397, note.)...I think that you ought to allude to these cases. I most fully agree that no problem is more interesting than that of the temperate forms in the southern hemisphere, common to the north. I remember writing about this after Wallace's book appeared, and hoping that you would take it up. The frequency with which the drainage from the land passes through mountain-chains seems to indicate some general law--viz., the successive formation of cracks and lines of elevation between the nearest ocean and the already upraised land; but that is too big a subject for a note. I doubt whether any insects can be shown with any probability to have been flower feeders before the middle of the Secondary period. Several of the asserted cases have broken down. Your long letter has stirred many pleasant memories of long past days, when we had many a discussion and many a good fight. LETTER 399. TO J.D. HOOKER. Down, August 21st, 1881. I cannot aid you much, or at all. I should think that no one could have thought on the modification of species without thinking of representative species. But I feel sure that no discussion of any importance had been published on this subject before the "Origin," for if I had known of it I should assuredly have alluded to it in the "Origin," as I wished to gain support from all quarters. I did not then know of Von Buch's view (alluded to in my Historical Introduction in all the later editions). Von Buch published his "Isles Canaries" in 1836, and he here briefly argues that plants spread over a continent and vary, and the varieties in time come to be species. He also argues that closely allied species have been thus formed in the SEPARATE valleys of the Canary Islands, but not on the upper and open parts. I could lend you Von Buch's book, if you like. I have just consulted the passage. I have not Baer's papers; but, as far as I remember, the subject is not fully discussed by him. I quite agree about Wallace's position on the ocean and continent question. To return to geographical distribution: As far as I know, no one ever discussed the meaning of the relation between representative species before I did, and, as I suppose, Wallace did in his paper before the Linnean Society. Von Buch's is the nearest approach to such discussion known to me. LETTER 400. TO W.D. CRICK. (400/1. The following letters are interesting not only for their own sake, but because they tell the history of the last of Mr. Darwin's publications--his letter to "Nature" on the "Dispersal of Freshwater Bivalves," April 6th, 1882.) Down, February 21st, 1882. Your fact is an interesting one, and I am very much obliged to you for communicating it to me. You speak a little doubtfully about the name of the shell, and it would be indispensable to have this ascertained with certainty. Do you know any good conchologist in Northampton who could name it? If so I should be obliged if you would inform me of the result. Also the length and breadth of the shell, and how much of leg (which leg?) of the Dytiscus [a large water-beetle] has been caught. If you cannot get the shell named I could take it to the British Museum when I next go to London; but this probably will not occur for about six weeks, and you may object to lend the specimen for so long a time. I am inclined to think that the case would be worth communicating to "Nature." P.S.--I suppose that the animal in the shell must have been alive when the Dytiscus was captured, otherwise the adductor muscle of the shell would have relaxed and the shell dropped off. LETTER 401. TO W.D. CRICK. Down, February 25th, 1882. I am much obliged for your clear and distinct answers to my questions. I am sorry to trouble you, but there is one point which I do not fully understand. Did the shell remain attached to the beetle's leg from the 18th to the 23rd, and was the beetle kept during this time in the air? Do I understand rightly that after the shell had dropped off, both being in water, that the beetle's antenna was again temporarily caught by the shell? I presume that I may keep the specimen till I go to London, which will be about the middle of next month. I have placed the shell in fresh-water, to see if the valve will open, and whether it is still alive, for this seems to me a very interesting point. As the wretched beetle was still feebly alive, I have put it in a bottle with chopped laurel leaves, that it may die an easy and quicker death. I hope that I shall meet with your approval in doing so. One of my sons tells me that on the coast of N. Wales the bare fishing hooks often bring up young mussels which have seized hold of the points; but I must make further enquiries on this head. LETTER 402. TO W.D. CRICK. Down, March 23rd, 1882. I have had a most unfortunate and extraordinary accident with your shell. I sent it by post in a strong box to Mr. Gwyn Jeffreys to be named, and heard two days afterwards that he had started for Italy. I then wrote to the servant in charge of his house to open the parcel (within which was a cover stamped and directed to myself) and return it to me. This servant, I suppose, opened the box and dropped the glass tube on a stone floor, and perhaps put his foot on it, for the tube and shell were broken into quite small fragments. These were returned to me with no explanation, the box being quite uninjured. I suppose you would not care for the fragments to be returned or the Dytiscus; but if you wish for them they shall be returned. I am very sorry, but it has not been my fault. It seems to me almost useless to send the fragments of the shell to the British Museum to be named, more especially as the umbo has been lost. It is many years since I have looked at a fresh-water shell, but I should have said that the shell was Cyclas cornea. (402/1. It was Cyclas cornea.) Is Sphaenium corneum a synonym of Cyclas? Perhaps you could tell by looking to Mr. G. Jeffreys' book. If so, may we venture to call it so, or shall I put an (?) to the name? As soon as I hear from you I will send my letter to "Nature." Do you take in "Nature," or shall I send you a copy? CHAPTER 2.VIII.--MAN. I. Descent of Man.--II. Sexual Selection.--III. Expression of the Emotions. 2.VIII.I. DESCENT OF MAN, 1860-1882. LETTER 403. TO C. LYELL. Down, April 27th [1860]. I cannot explain why, but to me it would be an infinite satisfaction to believe that mankind will progress to such a pitch that we should [look] back at [ourselves] as mere Barbarians. I have received proof-sheets (with a wonderfully nice letter) of very hostile review by Andrew Murray, read before the Royal Society of Edinburgh. (403/1. "On Mr. Darwin's Theory of the Origin of Species," by Andrew Murray. "Proc. Roy. Soc., Edinb." Volume IV., pages 274-91, 1862. The review concludes with the following sentence: "I have come to be of opinion that Mr. Darwin's theory is unsound, and that I am to be spared any collision between my inclination and my convictions" (referring to the writer's belief in Design).) But I am tired with answering it. Indeed I have done nothing the whole day but answer letters. LETTER 404. TO L. HORNER. (404/1. The following letter occurs in the "Memoir of Leonard Horner, edited by his daughter Katherine M. Lyell," Volume II., page 300 (privately printed, 1890).) Down, March 20th [1861]. I am very much obliged for your Address (404/2. Mr. Horner's Anniversary Address to the Geological Society ("Proc. Geol. Soc." XVII., 1861).) which has interested me much...I thought that I had read up pretty well on the antiquity of man; but you bring all the facts so well together in a condensed focus, that the case seems much clearer to me. How curious about the Bible! (404/3. At page lxviii. Mr. Horner points out that the "chronology, given in the margin of our Bibles," i.e., the statement that the world was created 4004 B.C., is the work of Archbishop Usher, and is in no way binding on those who believe in the inspiration of Scripture. Mr. Horner goes on (page lxx): "The retention of the marginal note in question is by no means a matter of indifference; it is untrue, and therefore it is mischievous." It is interesting that Archbishop Sumner and Dr. Dawes, Dean of Hereford, wrote with approbation of Mr. Horner's views on Man. The Archbishop says: "I have always considered the first verse of Genesis as indicating, rather than denying, a PREADAMITE world" ("Memoir of Leonard Horner, II.", page 303).) I declare I had fancied that the date was somehow in the Bible. You are coming out in a new light as a Biblical critic. I must thank you for some remarks on the "Origin of Species" (404/4. Mr. Horner (page xxxix) begins by disclaiming the qualifications of a competent critic, and confines himself to general remarks on the philosophic candour and freedom from dogmatism of the "Origin": he does, however, give an opinion on the geological chapters IX. and X. As a general criticism he quotes Mr. Huxley's article in the "Westminster Review," which may now be read in "Collected Essays," II., page 22.) (though I suppose it is almost as incorrect to do so as to thank a judge for a favourable verdict): what you have said has pleased me extremely. I am the more pleased, as I would rather have been well attacked than have been handled in the namby-pamby, old-woman style of the cautious Oxford Professor. (404/5. This no doubt refers to Professor Phillips' "Life on the Earth," 1860, a book founded on the author's "Rede Lecture," given before the University of Cambridge. Reference to this work will be found in "Life and Letters," II., pages 309, 358, 373.) LETTER 405. TO J.D. HOOKER. (405/1. Mr. Wallace was, we believe, the first to treat the evolution of Man in any detail from the point of view of Natural Selection, namely, in a paper in the "Anthropological Review and Journal of the Anthropological Society," May 1864, page clviii. The deep interest with which Mr. Darwin read his copy is graphically recorded in the continuous series of pencil-marks along the margins of the pages. His views are fully given in Letter 406. The phrase, "in this case it is too far," refers to Mr. Wallace's habit of speaking of the theory of Natural Selection as due entirely to Darwin.) May 22nd 1864. I have now read Wallace's paper on Man, and think it MOST striking and original and forcible. I wish he had written Lyell's chapters on Man. (405/2. See "Life and Letters," III., page 11 et seq. for Darwin's disappointment over Lyell's treatment of the evolutionary question in his "Antiquity of Man"; see also page 29 for Lyell's almost pathetic words about his own position between the discarded faith of many years and the new one not yet assimilated. See also Letters 132, 164, 170.) I quite agree about his high-mindedness, and have long thought so; but in this case it is too far, and I shall tell him so. I am not sure that I fully agree with his views about Man, but there is no doubt, in my opinion, on the remarkable genius shown by the paper. I agree, however, to the main new leading idea. LETTER 406. TO A.R. WALLACE. (406/1. This letter was published in "Life and Letters," III., page 89.) Down, [May] 28th [1864]. I am so much better that I have just finished a paper for the Linnean Society (406/2. On the three forms, etc., of Lythrum.); but I am not yet at all strong, I felt much disinclination to write, and therefore you must forgive me for not having sooner thanked you for your paper on Man (406/3. "Anthropological Review," May 1864.) received on the 11th. (406/4. Mr. Wallace wrote, May 10th, 1864: "I send you now my little contribution to the theory of the origin of man. I hope you will be able to agree with me. If you are able [to write] I shall be glad to have your criticisms. I was led to the subject by the necessity of explaining the vast mental and cranial differences between man and the apes combined with such small structural differences in other parts of the body,--and also by an endeavour to account for the diversity of human races combined with man's almost perfect stability of form during all historical epochs." But first let me say that I have hardly ever in my life been more struck by any paper than that on "Variation," etc., etc., in the "Reader." (406/5. "Reader," April 16th, 1864, an abstract of Mr. Wallace: "On the Phenomena of Variation and Geographical Distribution as illustrated by the Papilionidae of the Malayan Region." "Linn. Soc. Trans." XXV.) I feel sure that such papers will do more for the spreading of our views on the modification of species than any separate treatises on the simple subject itself. It is really admirable; but you ought not in the Man paper to speak of the theory as mine; it is just as much yours as mine. One correspondent has already noticed to me your "high-minded" conduct on this head. But now for your Man paper, about which I should like to write more than I can. The great leading idea is quite new to me--viz. that during late ages the mind will have been modified more than the body; yet I had got as far as to see with you, that the struggle between the races of man depended entirely on intellectual and moral qualities. The latter part of the paper I can designate only as grand and most eloquently done. I have shown your paper to two or three persons who have been here, and they have been equally struck with it. I am not sure that I go with you on all minor points: when reading Sir G. Grey's account of the constant battles of Australian savages, I remember thinking that Natural Selection would come in, and likewise with the Esquimaux, with whom the art of fishing and managing canoes is said to be hereditary. I rather differ on the rank, under a classificatory point of view, which you assign to man; I do not think any character simply in excess ought ever to be used for the higher divisions. Ants would not be separated from other hymenopterous insects, however high the instinct of the one, and however low the instincts of the other. With respect to the differences of race, a conjecture has occurred to me that much may be due to the correlation of complexion (and consequently hair) with constitution. Assume that a dusky individual best escaped miasma, and you will readily see what I mean. I persuaded the Director-General of the Medical Department of the Army to send printed forms to the surgeons of all regiments in tropical countries to ascertain this point, but I daresay I shall never get any returns. Secondly, I suspect that a sort of sexual selection has been the most powerful means of changing the races of man. I can show that the different races have a widely different standard of beauty. Among savages the most powerful men will have the pick of the women, and they will generally leave the most descendants. I have collected a few notes on man, but I do not suppose I shall ever use them. Do you intend to follow out your views? and if so, would you like at some future time to have my few references and notes? I am sure I hardly know whether they are of any value, and they are at present in a state of chaos. There is much more that I should like to write, but I have not strength. P.S. Our aristocracy is handsomer (more hideous according to a Chinese or Negro) than the middle classes, from [having the] pick of the women; but oh, what a scheme is primogeniture for destroying Natural Selection! I fear my letter will be barely intelligible to you. LETTER 406* A.R. WALLACE TO CHARLES DARWIN. 5, Westbourne Grove Terrace, W., May 29th [1864]. You are always so ready to appreciate what others do, and especially to overestimate my desultory efforts, that I cannot be surprised at your very kind and flattering remarks on my papers. I am glad, however, that you have made a few critical observations (and am only sorry that you were not well enough to make more), as that enables me to say a few words in explanation. My great fault is haste. An idea strikes me, I think over it for a few days, and then write away with such illustrations as occur to me while going on. I therefore look at the subject almost solely from one point of view. Thus, in my paper on Man (406*/1. Published in the "Anthropological Review," 1864.), I aim solely at showing that brutes are modified in a great variety of ways by Natural Selection, but that in none of these particular ways can Man be modified, because of the superiority of his intellect. I therefore no doubt overlook a few smaller points in which Natural Selection may still act on men and brutes alike. Colour is one of them, and I have alluded to this in correlation to constitution, in an abstract I have made at Sclater's request for the "Natural History Review." (406*/2. "Nat. Hist. Review," 1864, page 328.) At the same time, there is so much evidence of migrations and displacements of races of man, and so many cases of peoples of distinct physical characters inhabiting the same or similar regions, and also of races of uniform physical characters inhabiting widely dissimilar regions,--that the external characteristics of the chief races of man must, I think, be older than his present geographical distribution, and the modifications produced by correlation to favourable variations of constitution be only a secondary cause of external modification. I hope you may get the returns from the Army. (406*/3. Measurements taken of more than one million soldiers in the United States showed that "local influences of some kind act directly on structure."--"Descent of Man," 1901, page 45.) They would be very interesting, but I do not expect the results would be favourable to your view. With regard to the constant battles of savages leading to selection of physical superiority, I think it would be very imperfect and subject to so many exceptions and irregularities that it would produce no definite result. For instance: the strongest and bravest men would lead, and expose themselves most, and would therefore be most subject to wounds and death. And the physical energy which led to any one tribe delighting in war, might lead to its extermination, by inducing quarrels with all surrounding tribes and leading them to combine against it. Again, superior cunning, stealth, and swiftness of foot, or even better weapons, would often lead to victory as well as mere physical strength. Moreover, this kind of more or less perpetual war goes on amongst savage peoples. It could lead, therefore, to no differential characters, but merely to the keeping up of a certain average standard of bodily and mental health and vigour. So with selection of variations adapted to special habits of life as fishing, paddling, riding, climbing, etc., etc., in different races, no doubt it must act to some extent, but will it be ever so rigid as to induce a definite physical modification, and can we imagine it to have had any part in producing the distinct races that now exist? The sexual selection you allude to will also, I think, have been equally uncertain in its results. In the very lowest tribes there is rarely much polygamy, and women are more or less a matter of purchase. There is also little difference of social condition, and I think it rarely happens that any healthy and undeformed man remains without wife and children. I very much doubt the often-repeated assertion that our aristocracy are more beautiful than the middle classes. I allow that they present specimens of the highest kind of beauty, but I doubt the average. I have noticed in country places a greater average amount of good looks among the middle classes, and besides we unavoidably combine in our idea of beauty, intellectual expression, and refinement of manner, which often makes the less appear the more beautiful. Mere physical beauty--i.e. a healthy and regular development of the body and features approaching to the mean and type of European man, I believe is quite as frequent in one class of society as the other, and much more frequent in rural districts than in cities. With regard to the rank of man in zoological classification, I fear I have not made myself intelligible. I never meant to adopt Owen's or any other such views, but only to point out that from one point of view he was right. I hold that a distinct family for Man, as Huxley allows, is all that can possibly be given him zoologically. But at the same time, if my theory is true, that while the animals which surrounded him have been undergoing modification in all parts of their bodies to a generic or even family degree of difference, he has been changing almost wholly in the brain and head--then in geological antiquity the SPECIES man may be as old as many mammalian families, and the origin of the FAMILY man may date back to a period when some of the ORDERS first originated. As to the theory of Natural Selection itself, I shall always maintain it to be actually yours and yours only. You had worked it out in details I had never thought of, years before I had a ray of light on the subject, and my paper would never have convinced anybody or been noticed as more than an ingenious speculation, whereas your book has revolutionised the study of Natural History, and carried away captive the best men of the present age. All the merit I claim is the having been the means of inducing you to write and publish at once. I may possibly some day go a little more into this subject (of Man), and if I do will accept the kind offer of your notes. I am now, however, beginning to write the "Narrative of my Travels," which will occupy me a long time, as I hate writing narrative, and after Bates' brilliant success rather fear to fail. I shall introduce a few chapters on Geographical Distribution and other such topics. Sir C. Lyell, while agreeing with my main argument on Man, thinks I am wrong in wanting to put him back into Miocene times, and thinks I do not appreciate the immense interval even to the later Pliocene. But I still maintain my view, which in fact is a logical result of my theory; for if man originated in later Pliocene, when almost all mammalia were of closely allied species to those now living, and many even identical, then man has not been stationary in bodily structure while animals have been varying, and my theory will be proved to be all wrong. In Murchison's address to the Geographical Society, just delivered, he points out Africa as being the oldest existing land. He says there is no evidence of its having been ever submerged during the Tertiary epoch. Here then is evidently the place to find early man. I hope something good may be found in Borneo, and that the means may be found to explore the still more promising regions of tropical Africa, for we can expect nothing of man very early in Europe. It has given me great pleasure to find that there are symptoms of improvement in your health. I hope you will not exert yourself too soon or write more than is quite agreeable to you. I think I made out every word of your letter, though it was not always easy. (406*/4. For Wallace's later views see Letter 408, note.) LETTER 407. TO W. TURNER. (407/1. Sir William Turner is frequently referred to in the "Descent of Man" as having supplied Mr. Darwin with information.) Down, December 14th [1866]. Your kindness when I met you at the Royal Society makes me think that you would grant me the favour of a little information, if in your power. I am preparing a book on Domestic Animals, and as there has been so much discussion on the bearing of such views as I hold on Man, I have some thoughts of adding a chapter on this subject. The point on which I want information is in regard to any part which may be fairly called rudimentary in comparison with the same part in the Quadrumana or any other mammal. Now the os coccyx is rudimentary as a tail, and I am anxious to hear about its muscles. Mr. Flower found for me in some work that its one muscle (with striae) was supposed only to bring this bone back to its proper position after parturition. This seems to me hardly credible. He said he had never particularly examined this part, and when I mentioned your name, he said you were the most likely man to give me information. Are there any traces of other muscles? It seems strange if there are none. Do you know how the muscles are in this part in the anthropoid apes? The muscles of the ear in man may, I suppose, in most cases be considered as rudimentary; and so they seem to be in the anthropoids; at least, I am assured in the Zoological Gardens they do not erect their ears. I gather there are a good many muscles in various parts of the body which are in this same state: could you specify any of the best cases? The mammae in man are rudimentary. Are there any other glands or other organs which you can think of? I know I have no right whatever to ask all these questions, and can only say that I should be grateful for any information. If you tell me anything about the os coccyx or other structures, I hope that you will permit me to quote the statement on your authority, as that would add so greatly to its value. Pray excuse me for troubling you, and do not hurry yourself in the least in answering me. I do not know whether you would care to possess a copy, but I told my publisher to send you a copy of the new edition of the "Origin" last month. LETTER 408. TO W. TURNER. Down, February 1st [1867]. I thank you cordially for all your full information, and I regret much that I have given you such great trouble at a period when your time is so much occupied. But the facts were so valuable to me that I cannot pretend that I am sorry that I did trouble you; and I am the less so, as from what you say I hope you may be induced some time to write a full account of all rudimentary structures in Man: it would be a very curious and interesting memoir. I shall at present give only a brief abstract of the chief facts which you have so very kindly communicated to me, and will not touch on some of the doubtful points. I have received far more information than I ventured to anticipate. There is one point which has occurred to me, but I suspect there is nothing in it. If, however, there should be, perhaps you will let me have a brief note from you, and if I do not hear I will understand there is nothing in the notion. I have included the down on the human body and the lanugo on the foetus as a rudimentary representation of a hairy coat. (408/1. "Descent of Man" I., page 25; II., page 375.) I do not know whether there is any direct functional connection between the presence of hair and the panniculus carnosus (408/2. Professor Macalister draws our attention to the fact that Mr. Darwin uses the term panniculus in the generalised sense of any sheet of muscle acting on the skin.) (to put the question under another point of view, is it the primary or aboriginal function of the panniculus to move the dermal appendages or the skin itself?); but both are superficial, and would perhaps together become rudimentary. I was led to think of this by the places (as far as my ignorance of anatomy has allowed me to judge) of the rudimentary muscular fasciculi which you specify. Now, some persons can move the skin of their hairy heads; and is this not effected by the panniculus? How is it with the eyebrows? You specify the axillae and the front region of the chest and lower part of scapulae: now, these are all hairy spots in man. On the other hand, the neck, and as I suppose the covering of the gluteus medius, are not hairy; so, as I said, I presume there is nothing in this notion. If there were, the rudiments of the panniculus ought perhaps to occur more plainly in man than in woman... P.S.--If the skin on the head is moved by the panniculus, I think I ought just to allude to it, as some men alone having power to move the skin shows that the apparatus is generally rudimentary. (408/3. In March 1869 Darwin wrote to Mr. Wallace: "I shall be intensely curious to read the "Quarterly." I hope you have not murdered too completely your own and my child." The reference is to Mr. Wallace's review, in the April number of the "Quarterly," of Lyell's "Principles of Geology" (tenth edition), and of the sixth edition of the "Elements of Geology." Mr. Wallace points out that here for the first time Sir C. Lyell gave up his opposition to evolution; and this leads Mr. Wallace to give a short account of the views set forth in the "Origin of Species." In this article Mr. Wallace makes a definite statement as to his views on the evolution of man, which were opposed to those of Mr. Darwin. He upholds the view that the brain of man, as well as the organs of speech, the hand and the external form, could not have been evolved by Natural Selection (the child he is supposed to murder). At page 391 he writes: "In the brain of the lowest savages, and, as far as we know, of the prehistoric races, we have an organ...little inferior in size and complexity to that of the highest types...But the mental requirements of the lowest savages, such as the Australians or the Andaman Islanders, are very little above those of many animals...How, then, was an organ developed so far beyond the needs of its possessor? Natural Selection could only have endowed the savage with a brain a little superior to that of an ape, whereas he actually possesses one but very little inferior to that of the average members of our learned societies." This passage is marked in Mr. Darwin's copy with a triply underlined "No," and with a shower of notes of exclamation. It was probably the first occasion on which he realised the extent of this great and striking divergence in opinion between himself and his colleague. He had, however, some indication of it in Wallace's paper on Man, "Anthropological Review," 1864. (See Letter 406). He wrote to Lyell, May 4th, 1869, "I was dreadfully disappointed about Man; it seems to me incredibly strange." And to Mr. Wallace, April 14th, 1869, "If you had not told me, I should have thought that [your remarks on Man] had been added by some one else. As you expected, I differ grievously from you, and I am very sorry for it." LETTER 409. TO T.H. HUXLEY. Down, Thursday, February 21st [1868-70?]. I received the Jermyn Street programme, but have hardly yet considered it, for I was all day on the sofa on Tuesday and Wednesday. Bad though I was, I thought with constant pleasure of your very great kindness in offering to read the proofs of my essay on man. I do not know whether I said anything which might have appeared like a hint, but I assure you that such a thought had never even momentarily passed through my mind. Your offer has just made all the difference, that I can now write, whether or no my essay is ever printed, with a feeling of satisfaction instead of vague dread. Beg my colleague, Mrs. Huxley, not to forget the corrugator supercilii: it will not be easy to catch the exact moment when the child is on the point of crying, and is struggling against the wrinkling up [of] its little eyes; for then I should expect the corrugator, from being little under the command of the will, would come into play in checking or stopping the wrinkling. An explosion of tears would tell nothing. LETTER 410. TO FRANCIS GALTON. Down, December 23rd [1870?]. I have only read about fifty pages of your book (to the Judges) (410/1. "Hereditary Genius: an Inquiry into its Laws and Consequences," by Francis Galton, London, 1869. "The Judges of England between 1660 and 1865" is the heading of a section of this work (page 55). See "Descent of Man" (1901), page 41.), but I must exhale myself, else something will go wrong in my inside. I do not think I ever in all my life read anything more interesting and original. And how well and clearly you put every point! George, who has finished the book, and who expressed himself just in the same terms, tells me the earlier chapters are nothing in interest to the later ones! It will take me some time to get to these later chapters, as it is read aloud to me by my wife, who is also much interested. You have made a convert of an opponent in one sense, for I have always maintained that, excepting fools, men did not differ much in intellect, only in zeal and hard work; and I still think [this] is an eminently important difference. I congratulate you on producing what I am convinced will prove a memorable work. I look forward with intense interest to each reading, but it sets me thinking so much that I find it very hard work; but that is wholly the fault of my brain, and not of your beautifully clear style. LETTER 411. TO W.R. GREG. March 21st [1871?]. Many thanks for your note. I am very glad indeed to read remarks made by a man who possesses such varied and odd knowledge as you do, and who is so acute a reasoner. I have no doubt that you will detect blunders of many kinds in my book. (411/1. "The Descent of Man.") Your MS. on the proportion of the sexes at birth seems to me extremely curious, and I hope that some day you will publish it. It certainly appears that the males are decreasing in the London districts, and a most strange fact it is. Mr. Graham, however, I observe in a note enclosed, does not seem inclined to admit your conclusion. I have never much considered the subject of the causes of the proportion. When I reflected on queen bees producing only males when not impregnated, whilst some other parthenogenetic insects produced, as far as known, only females, the subject seemed to me hopelessly obscure. It is, however, pretty clear that you have taken the one path for its solution. I wished only to ascertain how far with various animals the males exceeded the females, and I have given all the facts which I could collect. As far as I know, no other data have been published. The equality of the sexes with race-horses is surprising. My remarks on mankind are quite superficial, and given merely as some sort of standard for comparison with the lower animals. M. Thury is the writer who makes the sex depend on the period of impregnation. His pamphlet was sent me from Geneva. (411/2. "Memoire sur la loi de Production des Sexes," 2nd edition, 1863 (a pamphlet published by Cherbuliez, Geneva).) I can lend it you if you like. I subsequently read an account of experiments which convinced me that M. Thury was in error; but I cannot remember what they were, only the impression that I might safely banish this view from my mind. Your remarks on the less ratio of males in illegitimate births strikes me as the most doubtful point in your MS.--requiring two assumptions, viz. that the fathers in such cases are relatively too young, and that the result is the same as when the father is relatively too old. My son, George, who is a mathematician, and who read your MS. with much interest, has suggested, as telling in the right direction, but whether sufficient is another question, that many more illegitimate children are murdered and concealed shortly after birth, than in the case of legitimate children; and as many more males than females die during the first few days of life, the census of illegitimate children practically applies to an older age than with legitimate children, and would thus slightly reduce the excess of males. This might possibly be worth consideration. By a strange coincidence a stranger writes to me this day, making the very same suggestion. I am quite delighted to hear that my book interests you enough to lead you to read it with some care. LETTER 412. TO FRANCIS GALTON. Down, January 4th, 1873. Very many thanks for "Fraser" (412/1. "Hereditary Improvement," by Francis Galton, "Fraser's Magazine," January 1873, page 116.): I have been greatly interested by your article. The idea of castes being spontaneously formed and leading to intermarriage (412/2. "My object is to build up, by the mere process of extensive enquiry and publication of results, a sentiment of caste among those who are naturally gifted, and to procure for them, before the system has fairly taken root, such moderate social favours and preference, no more no less, as would seem reasonable to those who were justly informed of the precise measure of their importance to the nation" (loc. cit., page 123).) is quite new to me, and I should suppose to others. I am not, however, so hopeful as you. Your proposed Society (412/3. Mr. Galton proposes that "Some society should undertake three scientific services: the first, by means of a moderate number of influential local agencies, to institute continuous enquiries into the facts of human heredity; the second to be a centre of information on heredity for breeders of animals and plants; and the third to discuss and classify the facts that were collected" (loc. cit., page 124).) would have awfully laborious work, and I doubt whether you could ever get efficient workers. As it is, there is much concealment of insanity and wickedness in families; and there would be more if there was a register. But the greatest difficulty, I think, would be in deciding who deserved to be on the register. How few are above mediocrity in health, strength, morals and intellect; and how difficult to judge on these latter heads. As far as I see, within the same large superior family, only a few of the children would deserve to be on the register; and these would naturally stick to their own families, so that the superior children of distinct families would have no good chance of associating much and forming a caste. Though I see so much difficulty, the object seems a grand one; and you have pointed out the sole feasible, yet I fear utopian, plan of procedure in improving the human race. I should be inclined to trust more (and this is part of your plan) to disseminating and insisting on the importance of the all-important principle of inheritance. I will make one or two minor criticisms. Is it not possible that the inhabitants of malarious countries owe their degraded and miserable appearance to the bad atmosphere, though this does not kill them, rather than to "economy of structure"? I do not see that an orthognathous face would cost more than a prognathous face; or a good morale than a bad one. That is a fine simile (page 119) about the chip of a statue (412/4. "...The life of the individual is treated as of absolutely no importance, while the race is as everything; Nature being wholly careless of the former except as a contributor to the maintenance and evolution of the latter. Myriads of inchoate lives are produced in what, to our best judgment, seems a wasteful and reckless manner, in order that a few selected specimens may survive, and be the parents of the next generation. It is as though individual lives were of no more consideration than are the senseless chips which fall from the chisel of the artist who is elaborating some ideal form from a rude block" (loc. cit., page 119).); but surely Nature does not more carefully regard races than individuals, as (I believe I have misunderstood what you mean) evidenced by the multitude of races and species which have become extinct. Would it not be truer to say that Nature cares only for the superior individuals and then makes her new and better races? But we ought both to shudder in using so freely the word "Nature" (412/5. See Letter 190, Volume I.) after what De Candolle has said. Again let me thank you for the interest received in reading your essay. Many thanks about the rabbits; your letter has been sent to Balfour: he is a very clever young man, and I believe owes his cleverness to Salisbury blood. This letter will not be worth your deciphering. I have almost finished Greg's "Enigmas." (412/6. "The Enigmas of Life," 1872.) It is grand poetry--but too Utopian and too full of faith for me; so that I have been rather disappointed. What do you think about it? He must be a delightful man. I doubt whether you have made clear how the families on the Register are to be kept pure or superior, and how they are to be in course of time still further improved. LETTER 413. TO MAX MULLER. Down, July 3rd, 1873. (413/1. In June, 1873, Professor Max Muller sent to Mr. Darwin a copy of the sixth edition of his "Lectures on the Science of Language" (413/2. A reference to the first edition occurs in "Life and Letters," II., page 390.), with a letter concluding with these words: "I venture to send you my three lectures, trusting that, though I differ from some of your conclusions, you will believe me to be one of your diligent readers and sincere admirers.") I am much obliged for your kind note and present of your lectures. I am extremely glad to have received them from you, and I had intended ordering them. I feel quite sure from what I have read in your works that you would never say anything of an honest adversary to which he would have any just right to object; and as for myself, you have often spoken highly of me--perhaps more highly than I deserve. As far as language is concerned I am not worthy to be your adversary, as I know extremely little about it, and that little learnt from very few books. I should have been glad to have avoided the whole subject, but was compelled to take it up as well as I could. He who is fully convinced, as I am, that man is descended from some lower animal, is almost forced to believe a priori that articulate language has been developed from inarticulate cries (413/3. "Descent of Man" (1901), page 133.); and he is therefore hardly a fair judge of the arguments opposed to this belief. (413/4. In October, 1875, Mr. Darwin again wrote cordially to Professor Max Muller on receipt of a pamphlet entitled "In Self-Defence" (413/5. Printed in "Chips from a German Workshop," Volume IV., 1875, page 473.), which is a reply to Professor Whitney's "Darwinism and Language" in the "North American Review," July 1874. This essay had been brought before the "general reader" in England by an article of Mr. G. Darwin's in the "Contemporary Review," November, 1874, page 894, entitled, "Professor Whitney on the Origin of Language." The article was followed by "My reply to Mr. Darwin," contributed by Professor Muller to the "Contemporary Review," January, 1875, page 305.) LETTER 414. G. ROLLESTON TO CHARLES DARWIN. British Association, Bristol, August 30th, 1875. (414/1. In the first edition of the "Descent of Man" Mr. Darwin wrote: "It is a more curious fact that savages did not formerly waste away, as Mr. Bagehot has remarked, before the classical nations, as they now do before modern civilised nations..."(414/2. Bagehot, "Physics and Politics," "Fortnightly Review," April, 1868, page 455.) In the second edition (page 183) the statement remains, but a mass of evidence (pages 183-92) is added, to which reference occurs in the reply to the following letter.) At pages 4-5 of the enclosed Address (414/3. "British Association Reports," 1875, page 142.) you will find that I have controverted Mr. Bagehot's view as to the extinction of the barbarians in the times of classical antiquity, as also the view of Poppig as to there being some occult influence exercised by civilisation to the disadvantage of savagery when the two come into contact. I write to say that I took up this subject without any wish to impugn any views of yours as such, but with the desire of having my say upon certain anti-sanitarian transactions and malfeasance of which I had had a painful experience. On reading however what I said, and had written somewhat hastily, it has struck me that what I have said might bear the former interpretation in the eyes of persons who might not read other papers of mine, and indeed other parts of the same Address, in which my adhesion, whatever it is worth, to your views in general is plainly enough implied. I have ventured to write this explanation to you for several reasons. LETTER 415. TO G. ROLLESTON. Bassett, Southampton, September 2nd [1875]. I am much obliged to you for having sent me your Address, which has interested me greatly. I quite subscribe to what you say about Mr. Bagehot's striking remark, and wish I had not quoted it. I can perceive no sort of reflection or blame on anything which I have written, and I know well that I deserve many a good slap on the face. The decrease of savage populations interests me much, and I should like you some time to look at a discussion on this subject which I have introduced in the second edition of the "Descent of Man," and which you can find (for I have no copy here) in the list of additions. The facts have convinced me that lessened fertility and the poor constitution of the children is one chief cause of such decrease; and that the case is strictly parallel to the sterility of many wild animals when made captive, the civilisation of savages and the captivity of wild animals leading to the same result. LETTER 416. TO ERNST KRAUSE. Down, June 30th, 1877. I have been much interested by your able argument against the belief that the sense of colour has been recently acquired by man. (416/1. See "Kosmos," June 1877, page 264, a review of Dr. Hugo Magnus' "Die Geschichtliche Entwickelung des Farbensinnes," 1877. The first part is chiefly an account of the author's views; Dr. Krause's argument begins at page 269. The interest felt by Mr. Darwin is recorded by the numerous pencil-marks on the margin of his copy.) The following observation bears on this subject. I attended carefully to the mental development of my young children, and with two, or as I believe three of them, soon after they had come to the age when they knew the names of all common objects, I was startled by observing that they seemed quite incapable of affixing the right names to the colours in coloured engravings, although I tried repeatedly to teach them. I distinctly remember declaring that they were colour-blind, but this afterwards proved a groundless fear. On communicating this fact to another person he told me that he had observed a nearly similar case. Therefore the difficulty which young children experience either in distinguishing, or more probably in naming colours, seems to deserve further investigation. I will add that it formerly appeared to me that the gustatory sense, at least in the case of my own infants, and very young children, differed from that of grown-up persons. This was shown by their not disliking rhubarb mixed with a little sugar and milk, which is to us abominably nauseous; and in their strong taste for the sourest and most austere fruits, such as unripe gooseberries and crabapples. (PLATE: G.J. ROMANES, 1891. Elliott & Fry, photo. Walker and Cockerell, ph. sc.) LETTER 417. TO G.J. ROMANES. [Barlaston], August 20th, 1878. (417/1. Part of this letter (here omitted) is published in "Life and Letters," III., page 225, and the whole in the "Life and Letters of G.J. Romanes," page 74. The lecture referred to was on animal intelligence, and was given at the Dublin meeting of the British Association.) ...The sole fault which I find with your lecture is that it is too short, and this is a rare fault. It strikes me as admirably clear and interesting. I meant to have remonstrated that you had not discussed sufficiently the necessity of signs for the formation of abstract ideas of any complexity, and then I came on the discussion on deaf mutes. This latter seems to me one of the richest of all the mines, and is worth working carefully for years, and very deeply. I should like to read whole chapters on this one head, and others on the minds of the higher idiots. Nothing can be better, as it seems to me, than your several lines or sources of evidence, and the manner in which you have arranged the whole subject. Your book will assuredly be worth years of hard labour; and stick to your subject. By the way, I was pleased at your discussing the selection of varying instincts or mental tendencies; for I have often been disappointed by no one having ever noticed this notion. I have just finished "La Psychologie, son Present et son Avenir," 1876, by Delboeuf (a mathematician and physicist of Belgium) in about a hundred pages. It has interested me a good deal, but why I hardly know; it is rather like Herbert Spencer. If you do not know it, and would care to see it, send me a postcard. Thank Heaven, we return home on Thursday, and I shall be able to go on with my humdrum work, and that makes me forget my daily discomfort. Have you ever thought of keeping a young monkey, so as to observe its mind? At a house where we have been staying there were Sir A. and Lady Hobhouse, not long ago returned from India, and she and he kept [a] young monkey and told me some curious particulars. One was that her monkey was very fond of looking through her eyeglass at objects, and moved the glass nearer and further so as to vary the focus. This struck me, as Frank's son, nearly two years old (and we think much of his intellect!!) is very fond of looking through my pocket lens, and I have quite in vain endeavoured to teach him not to put the glass close down on the object, but he always will do so. Therefore I conclude that a child under two years is inferior in intellect to a monkey. Once again I heartily congratulate you on your well-earned present, and I feel assured, grand future success. (417/2. Later in the year Mr. Darwin wrote: "I am delighted to hear that you mean to work the comparative Psychology well. I thought your letter to the "Times" very good indeed. (417/3. Romanes wrote to the "Times" August 28th, 1878, expressing his views regarding the distinction between man and the lower animals, in reply to criticisms contained in a leading article in the "Times" of August 23rd on his lecture at the Dublin meeting of the British Association.) Bartlett, at the Zoological Gardens, I feel sure, would advise you infinitely better about hardiness, intellect, price, etc., of monkey than F. Buckland; but with him it must be viva voce. "Frank says you ought to keep a idiot, a deaf mute, a monkey, and a baby in your house.") LETTER 418. TO G.A. GASKELL. Down, November 15th, 1878. (418/1. This letter has been published in Clapperton's "Scientific Meliorism," 1885, page 340, together with Mr. Gaskell's letter of November 13th (page 337). Mr. Gaskell's laws are given in his letter of November 13th, 1878. They are:-- I. The Organological Law: Natural Selection, or the Survival of the Fittest. II. The Sociological Law: Sympathetic Selection, or Indiscriminate Survival. III. The Moral Law: Social Selection, or the Birth of the Fittest.) Your letter seems to me very interesting and clearly expressed, and I hope that you are in the right. Your second law appears to be largely acted on in all civilised countries, and I just alluded to it in my remarks to the effect (as far as I remember) that the evil which would follow by checking benevolence and sympathy in not fostering the weak and diseased would be greater than by allowing them to survive and then to procreate. With regard to your third law, I do not know whether you have read an article (I forget when published) by F. Galton, in which he proposes certificates of health, etc., for marriage, and that the best should be matched. I have lately been led to reflect a little, (for, now that I am growing old, my work has become [word indecipherable] special) on the artificial checks, but doubt greatly whether such would be advantageous to the world at large at present, however it may be in the distant future. Suppose that such checks had been in action during the last two or three centuries, or even for a shorter time in Britain, what a difference it would have made in the world, when we consider America, Australia, New Zealand, and S. Africa! No words can exaggerate the importance, in my opinion, of our colonisation for the future history of the world. If it were universally known that the birth of children could be prevented, and this were not thought immoral by married persons, would there not be great danger of extreme profligacy amongst unmarried women, and might we not become like the "arreoi" societies in the Pacific? In the course of a century France will tell us the result in many ways, and we can already see that the French nation does not spread or increase much. I am glad that you intend to continue your investigations, and I hope ultimately may publish on the subject. LETTER 419. TO K. HOCHBERG. Down, January 13th, 1879. I am much obliged for your note and for the essay which you have sent me. I am a poor german scholar, and your german is difficult; but I think that I understand your meaning, and hope at some future time, when more at leisure, to recur to your essay. As far as I can judge, you have made a great advance in many ways in the subject; and I will send your paper to Mr. Edmund Gurney (The late Edmund Gurney, author of "The Power of Sound," 1880.), who has written on and is much interested in the origin of the taste for music. In reading your essay, it occurred to me that facility in the utterance of prolonged sounds (I do not think that you allude to this point) may possibly come into play in rendering them musical; for I have heard it stated that those who vary their voices much, and use cadences in long continued speaking, feel less fatigued than those who speak on the same note. LETTER 420. TO G.J. ROMANES. Down, February 5th, 1880. (420/1. Romanes was at work on what ultimately came to be a book on animal intelligence. Romanes's reply to this letter is given in his "Life," page 95. The table referred to is published as a frontispiece to his "Mental Evolution in Animals," 1885.) As I feared, I cannot be of the least use to you. I could not venture to say anything about babies without reading my Expression book and paper on Infants, or about animals without reading the "Descent of Man" and referring to my notes; and it is a great wrench to my mind to change from one subject to another. I will, however, hazard one or two remarks. Firstly, I should have thought that the word "love" (not sexual passion), as shown very low in the scale, to offspring and apparently to comrades, ought to have come in more prominently in your table than appears to be the case. Secondly, if you give any instance of the appreciation of different stimulants by plants, there is a much better case than that given by you--namely, that of the glands of Drosera, which can be touched roughly two or three times and do not transmit any effect, but do so if pressed by a weight of 1/78000 grain ("Insectivorous Plants" 263). On the other hand, the filament of Dionoea may be quietly loaded with a much greater weight, while a touch by a hair causes the lobes to close instantly. This has always seemed to me a marvellous fact. Thirdly, I have been accustomed to look at the coming in of the sense of pleasure and pain as one of the most important steps in the development of mind, and I should think it ought to be prominent in your table. The sort of progress which I have imagined is that a stimulus produced some effect at the point affected, and that the effect radiated at first in all directions, and then that certain definite advantageous lines of transmission were acquired, inducing definite reaction in certain lines. Such transmission afterwards became associated in some unknown way with pleasure or pain. These sensations led at first to all sorts of violent action, such as the wriggling of a worm, which was of some use. All the organs of sense would be at the same time excited. Afterwards definite lines of action would be found to be the most useful, and so would be practised. But it is of no use my giving you my crude notions. LETTER 421. TO S. TOLVER PRESTON. Down, May 22nd, 1880. (421/1. Mr. Preston wrote (May 20th, 1880) to the effect that "self-interest as a motive for conduct is a thing to be commended--and it certainly [is] I think...the only conceivable rational motive of conduct: and always is the tacitly recognised motive in all rational actions." Mr. Preston does not, of course, commend selfishness, which is not true self-interest. There seem to be two ways of looking at the case given by Darwin. The man who knows that he is risking his life,--realising that the personal satisfaction that may follow is not worth the risk--is surely admirable from the strength of character that leads him to follow the social instinct against his purely personal inclination. But the man who blindly obeys the social instinct is a more useful member of a social community. He will act with courage where even the strong man will fail.) Your letter appears to me an interesting and valuable one; but I have now been working for some years exclusively on the physiology of plants, and all other subjects have gone out of my head, and it fatigues me much to try and bring them back again into my head. I am, moreover, at present very busy, as I leave home for a fortnight's rest at the beginning of next week. My conviction as yet remains unchanged, that a man who (for instance) jumps into a river to save a life without a second's reflection (either from an innate tendency or from one gained by habit) is deservedly more honoured than a man who acts deliberately and is conscious, for however short a time, that the risk and sacrifice give him some inward satisfaction. You are of course familiar with Herbert Spencer's writings on Ethics. (422/1. The observations to which the following letters refer were continued by Mr. Wallis, who gave an account of his work in an interesting paper in the "Proceedings of the Zoological Society," March 2nd, 1897. The results on the whole confirm the belief that traces of an ancestral pointed ear exist in man.) LETTER 422. TO H.M. WALLIS. Down, March 22nd, 1881. I am very much obliged for your courteous and kind note. The fact which you communicate is quite new to me, and as I was laughed at about the tips to human ears, I should like to publish in "Nature" some time your fact. But I must first consult Eschricht, and see whether he notices this fact in his curious paper on the lanugo on human embryos; and secondly I ought to look to monkeys and other animals which have tufted ears, and observe how the hair grows. This I shall not be able to do for some months, as I shall not be in London until the autumn so as to go to the Zoological Gardens. But in order that I may not hereafter throw away time, will you be so kind as to inform me whether I may publish your observation if on further search it seems desirable? LETTER 423. TO H.M. WALLIS. Down, March 31st, 1881. I am much obliged for your interesting letter. I am glad to hear that you are looking to other ears, and will visit the Zoological Gardens. Under these circumstances it would be incomparably better (as more authentic) if you would publish a notice of your observations in "Nature" or some scientific journal. Would it not be well to confine your attention to infants, as more likely to retain any primordial character, and offering less difficulty in observing. I think, though, it would be worth while to observe whether there is any relation (though probably none) between much hairiness on the ears of an infant and the presence of the "tip" on the folded margin. Could you not get an accurate sketch of the direction of the hair of the tip of an ear? The fact which you communicate about the goat-sucker is very curious. About the difference in the power of flight in Dorkings, etc., may it not be due merely to greater weight of body in the adults? I am so old that I am not likely ever again to write on general and difficult points in the theory of Evolution. I shall use what little strength is left me for more confined and easy subjects. LETTER 424. TO MRS. TALBOT. (Mrs. Emily Talbot was secretary of the Education Department of the American Social Science Association, Boston, Mass. A circular and register was issued by the Department, and answers to various questions were asked for. See "Nature," April 28th, page 617, 1881. The above letter was published in "The Field Naturalist," Manchester, 1883, page 5, edited by Mr. W.E. Axon, to whom we are indebted for a copy.) Down, July 19th [1881?] In response to your wish, I have much pleasure in expressing the interest which I feel in your proposed investigation on the mental and bodily development of infants. Very little is at present accurately known on this subject, and I believe that isolated observations will add but little to our knowledge, whereas tabulated results from a very large number of observations, systematically made, would probably throw much light on the sequence and period of development of the several faculties. This knowledge would probably give a foundation for some improvement in our education of young children, and would show us whether the system ought to be followed in all cases. I will venture to specify a few points of inquiry which, as it seems to me, possess some scientific interest. For instance, does the education of the parents influence the mental powers of their children at any age, either at a very early or somewhat more advanced stage? This could perhaps be learned by schoolmasters and mistresses if a large number of children were first classed according to age and their mental attainments, and afterwards in accordance with the education of their parents, as far as this could be discovered. As observation is one of the earliest faculties developed in young children, and as this power would probably be exercised in an equal degree by the children of educated and uneducated persons, it seems not impossible that any transmitted effect from education could be displayed only at a somewhat advanced age. It would be desirable to test statistically, in a similar manner, the truth of the oft-repeated statement that coloured children at first learn as quickly as white children, but that they afterwards fall off in progress. If it could be proved that education acts not only on the individual, but, by transmission, on the race, this would be a great encouragement to all working on this all-important subject. It is well known that children sometimes exhibit, at a very early age, strong special tastes, for which no cause can be assigned, although occasionally they may be accounted for by reversion to the taste or occupation of some progenitor; and it would be interesting to learn how far such early tastes are persistent and influence the future career of the individual. In some instances such tastes die away without apparently leaving any after effect, but it would be desirable to know how far this is commonly the case, as we should then know whether it were important to direct as far as this is possible the early tastes of our children. It may be more beneficial that a child should follow energetically some pursuit, of however trifling a nature, and thus acquire perseverance, than that he should be turned from it because of no future advantage to him. I will mention one other small point of inquiry in relation to very young children, which may possibly prove important with respect to the origin of language; but it could be investigated only by persons possessing an accurate musical ear. Children, even before they can articulate, express some of their feelings and desires by noises uttered in different notes. For instance, they make an interrogative noise, and others of assent and dissent, in different tones; and it would, I think, be worth while to ascertain whether there is any uniformity in different children in the pitch of their voices under various frames of mind. I fear that this letter can be of no use to you, but it will serve to show my sympathy and good wishes in your researches. 2.VIII.II. SEXUAL SELECTION, 1866-1872. LETTER 425. TO JAMES SHAW. Down, February 11th [1866]. I am much obliged to you for your kindness in sending me an abstract of your paper on beauty. (425/1. A newspaper report of a communication to the "Dumfries Antiquarian and Natural History Society.") In my opinion you take quite a correct view of the subject. It is clear that Dr. Dickson has either never seen my book, or overlooked the discussion on sexual selection. If you have any precise facts on birds' "courtesy towards their own image in mirror or picture," I should very much like to hear them. Butterflies offer an excellent instance of beauty being displayed in conspicuous parts; for those kinds which habitually display the underside of the wing have this side gaudily coloured, and this is not so in the reverse case. I daresay you will know that the males of many foreign butterflies are much more brilliantly coloured than the females, as in the case of birds. I can adduce good evidence from two large classes of facts (too large to specify) that flowers have become beautiful to make them conspicuous to insects. (425/2. This letter is published in "A Country Schoolmaster, James Shaw." Edited by Robert Wallace, Edinburgh, 1899.) (425/3. Mr. Darwin wrote again to Mr. Shaw in April, 1866:--) I am much obliged for your kind letter and all the great trouble which you have taken in sending to all the various and interesting facts on birds admiring themselves. I am very glad to hear of these facts. I have just finished writing and adding to a new edition of the "Origin," and in this I have given, without going into details (so that I shall not be able to use your facts), some remarks on the subject of beauty. LETTER 426. TO A.D. BARTLETT. Down, February 16th [1867?] I want to beg two favours of you. I wish to ascertain whether the Bower-Bird discriminates colours. (426/1. Mr. Bartlett does not seem to have supplied any information on the point in question. The evidence for the Bower-Bird's taste in colour is in "Descent of Man," II., page 112.) Will you have all the coloured worsted removed from the cage and bower, and then put all in a row, at some distance from bower, the enclosed coloured worsted, and mark whether the bird AT FIRST makes any selection. Each packet contains an equal quantity; the packets had better be separate, and each thread put separate, but close together; perhaps it would be fairest if the several colours were put alternately--one thread of bright scarlet, one thread of brown, etc., etc. There are six colours. Will you have the kindness to tell me whether the birds prefer one colour to another? Secondly, I very much want several heads of the fancy and long-domesticated rabbits, to measure the capacity of skull. I want only small kinds, such as Himalaya, small Angora, Silver Grey, or any small-sized rabbit which has long been domesticated. The Silver Grey from warrens would be of little use. The animals must be adult, and the smaller the breed the better. Now when any one dies would you send me the carcase named; if the skin is of any value it might be skinned, but it would be rather better with skin, and I could make a present to any keeper to whom the skin is a perquisite. This would be of great assistance to me, if you would have the kindness thus to aid me. LETTER 427. TO W.B. TEGETMEIER. (427/1. We are not aware that the experiment here suggested has ever been carried out.) Down, March 5th [1867]. I write on the bare and very improbable chance of your being able to try, or get some trustworthy person to try, the following little experiment. But I may first state, as showing what I want, that it has been stated that if two long feathers in the tail of the male Widow-Bird at the Cape of Good Hope are pulled out, no female will pair with him. Now, where two or three common cocks are kept, I want to know, if the tail sickle-feathers and saddle-feathers of one which had succeeded in getting wives were cut and mutilated and his beauty spoiled, whether he would continue to be successful in getting wives. This might be tried with drakes or peacocks, but no one would be willing to spoil for a season his peacocks. I have no strength or opportunity of watching my own poultry, otherwise I would try it. I would very gladly repay all expenses of loss of value of the poultry, etc. But, as I said, I have written on the most improbable chance of your interesting any one to make the trial, or having time and inclination yourself to make it. Another, and perhaps better, mode of making the trial would be to turn down to some hens two or three cocks, one being injured in its plumage. I am glad to say that I have begun correcting proofs. (427/2. "The Variation of Animals and Plants.") I hope that you received safely the skulls which you so kindly lent me. LETTER 428. TO W.B. TEGETMEIER. Down, March 30th [1867]. I am much obliged for your note, and shall be truly obliged if you will insert any question on the subject. That is a capital remark of yours about the trimmed game cocks, and shall be quoted by me. (428/1. "Descent of Man," Edition I., Volume II., page 117. "Mr. Tegetmeier is convinced that a game cock, though disfigured by being dubbed with his hackles trimmed, would be accepted as readily as a male retaining all his natural ornaments.") Nevertheless I am still inclined from many facts strongly to believe that the beauty of the male bird determines the choice of the female with wild birds, however it may be under domestication. Sir R. Heron has described how one pied peacock was extra attentive to the hens. This is a subject which I must take up as soon as my present book is done. I shall be most particularly obliged to you if you will dye with magenta a pigeon or two. (428/2. "Mr. Tegetmeier, at my request, stained some of his birds with magenta, but they were not much noticed by the others."--"Descent of Man" (1901), page 637.) Would it not be better to dye the tail alone and crown of head, so as not to make too great difference? I shall be very curious to hear how an entirely crimson pigeon will be received by the others as well as his mate. P.S.--Perhaps the best experiment, for my purpose, would be to colour a young unpaired male and turn him with other pigeons, and observe whether he was longer or quicker than usual in mating. LETTER 429. TO A.R. WALLACE. Down, April 29th [1867]. I have been greatly interested by your letter, but your view is not new to me. (429/1. We have not been able to find Mr. Wallace's letter to which this is a reply. It evidently refers to Mr. Wallace's belief in the paramount importance of protection in the evolution of colour. This is clear from the P.S. to the present letter and from the passages in the "Origin" referred to. The first reference, Edition IV., page 240, is as follows: "We can sometimes plainly see the proximate cause of the transmission of ornaments to the males alone; for a pea-hen with the long tail of the male bird would be badly fitted to sit on her eggs, and a coal-black female capercailzie would be far more conspicuous on her nest, and more exposed to danger, than in her present modest attire." The passages in Edition I. (pages 89, 101) do not directly bear on the question of protection.) If you will look at page 240 of the fourth edition of the "Origin" you will find it very briefly given with two extreme examples of the peacock and black grouse. A more general statement is given at page 101, or at page 89 of the first edition, for I have long entertained this view, though I have never had space to develop it. But I had not sufficient knowledge to generalise as far as you do about colouring and nesting. In your paper perhaps you will just allude to my scanty remark in the fourth edition, because in my Essay on Man I intend to discuss the whole subject of sexual selection, explaining as I believe it does much with respect to man. I have collected all my old notes, and partly written my discussion, and it would be flat work for me to give the leading idea as exclusively from you. But, as I am sure from your greater knowledge of Ornithology and Entomology that you will write a much better discussion than I could, your paper will be of great use to me. Nevertheless I must discuss the subject fully in my Essay on Man. When we met at the Zoological Society, and I asked you about the sexual differences in kingfishers, I had this subject in view; as I had when I suggested to Bates the difficulty about gaudy caterpillars, which you have so admirably (as I believe it will prove) explained. (429/2. See a letter of February 26th, 1867, to Mr. Wallace, "Life and Letters" III., page 94.) I have got one capital case (genus forgotten) of a [Australian] bird in which the female has long tail-plumes, and which consequently builds a different nest from all her allies. (429/3. Menura superba: see "Descent of Man" (1901), page 687. Rhynchoea, mentioned a line or two lower down, is discussed in the "Descent," page 727. The female is more brightly coloured than the male, and has a convoluted trachea, elsewhere a masculine character. There seems some reason to suppose that "the male undertakes the duty of incubation.") With respect to certain female birds being more brightly coloured than the males, and the latter incubating, I have gone a little into the subject, and cannot say that I am fully satisfied. I remember mentioning to you the case of Rhynchoea, but its nesting seems unknown. In some other cases the difference in brightness seemed to me hardly sufficiently accounted for by the principle of protection. At the Falkland Islands there is a carrion hawk in which the female (as I ascertained by dissection) is the brightest coloured, and I doubt whether protection will here apply; but I wrote several months ago to the Falklands to make enquiries. The conclusion to which I have been leaning is that in some of these abnormal cases the colour happened to vary in the female alone, and was transmitted to females alone, and that her variations have been selected through the admiration of the male. It is a very interesting subject, but I shall not be able to go on with it for the next five or six months, as I am fully employed in correcting dull proof-sheets. When I return to the work I shall find it much better done by you than I could have succeeded in doing. It is curious how we hit on the same ideas. I have endeavoured to show in my MS. discussion that nearly the same principles account for young birds not being gaily coloured in many cases, but this is too complex a point for a note. On reading over your letter again, and on further reflection, I do not think (as far as I remember my words) that I expressed myself nearly strongly enough on the value and beauty of your generalisation (429/4. See Letter 203, Volume I.), viz., that all birds in which the female is conspicuously or brightly coloured build in holes or under domes. I thought that this was the explanation in many, perhaps most cases, but do not think I should ever have extended my view to your generalisation. Forgive me troubling you with this P.S. LETTER 430. TO A.R. WALLACE. Down, May 5th [1867]. The offer of your valuable notes is most generous, but it would vex me to take so much from you, as it is certain that you could work up the subject very much better than I could. Therefore I earnestly, and without any reservation, hope that you will proceed with your paper, so that I return your notes. You seem already to have well investigated the subject. I confess on receiving your note that I felt rather flat at my recent work being almost thrown away, but I did not intend to show this feeling. As a proof how little advance I had made on the subject, I may mention that though I had been collecting facts on the colouring, and other sexual differences in mammals, your explanation with respect to the females had not occurred to me. I am surprised at my own stupidity, but I have long recognised how much clearer and deeper your insight into matters is than mine. I do not know how far you have attended to the laws of inheritance, so what follows may be obvious to you. I have begun my discussion on sexual selection by showing that new characters often appear in one sex and are transmitted to that sex alone, and that from some unknown cause such characters apparently appear oftener in the male than in the female. Secondly, characters may be developed and be confined to the male, and long afterwards be transferred to the female. Thirdly, characters may arise in either sex and be transmitted to both sexes, either in an equal or unequal degree. In this latter case I have supposed that the survival of the fittest has come into play with female birds and kept the female dull-coloured. With respect to the absence of spurs in the female gallinaceous birds, I presume that they would be in the way during incubation; at least I have got the case of a German breed of fowls in which the hens were spurred, and were found to disturb and break their eggs much. With respect to the females of deer not having horns, I presume it is to save the loss of organised matter. In your note you speak of sexual selection and protection as sufficient to account for the colouring of all animals, but it seems to me doubtful how far this will come into play with some of the lower animals, such as sea anemones, some corals, etc., etc. On the other hand Hackel (430/1. See "Descent of Man" (1901) page 402.) has recently well shown that the transparency and absence of colour in the lower oceanic animals, belonging to the most different classes, may be well accounted for on the principle of protection. Some time or other I should like much to know where your paper on the nests of birds has appeared, and I shall be extremely anxious to read your paper in the "Westminster Review." (430/2. "Westminster Review," July, 1867.) Your paper on the sexual colouring of birds will, I have no doubt, be very striking. Forgive me, if you can, for a touch of illiberality about your paper. LETTER 431. TO A.R. WALLACE. March 19th, 1868. (431/1. "The Variation of Animals and Plants" having been published on January 30th, 1868, Mr. Darwin notes in his diary that on February 4th he "Began on Man and Sexual Selection." He had already (in 1864 and 1867) corresponded with Mr. Wallace on these questions--see for instance the "Life and Letters," III., page 89; but, owing to various interruptions, serious work on the subject did not begin until 1869. The following quotations show the line of work undertaken early in 1868. Mr. Wallace wrote (March 19th, 1868): "I am glad you have got good materials on sexual selection. It is no doubt a difficult subject. One difficulty to me is, that I do not see how the constant MINUTE variations, which are sufficient for Natural Selection to work with, could be SEXUALLY selected. We seem to require a series of bold and abrupt variations. How can we imagine that an inch in the tail of the peacock, or 1/4-inch in that of the Bird of Paradise, would be noticed and preferred by the female.") In regard to sexual selection. A girl sees a handsome man, and without observing whether his nose or whiskers are the tenth of an inch longer or shorter than in some other man, admires his appearance and says she will marry him. So, I suppose, with the pea-hen; and the tail has been increased in length merely by, on the whole, presenting a more gorgeous appearance. J. Jenner Weir, however, has given me some facts showing that birds apparently admire details of plumage. LETTER 432. TO F. MULLER. March 28th [1868]. I am particularly obliged to you for your observations on the stridulation of the two sexes of Lamellicorns. (432/1. We are unable to find any mention of F. Muller's observations on this point; but the reference is clearly to Darwin's observations on Necrophorus and Pelobius, in which the stridulating rasp was bigger in the males in the first individuals examined, but not so in succeeding specimens. "Descent of Man," Edition II., Volume I., page 382.) I begin to fear that I am completely in error owing to that common cause, viz. mistaking at first individual variability for sexual difference. I go on working at sexual selection, and, though never idle, I am able to do so little work each day that I make very slow progress. I knew from Azara about the young of the tapir being striped, and about young deer being spotted (432/2. Fritz Muller's views are discussed in the "Descent of Man," Edition II., Volume II., page 305.); I have often reflected on this subject, and know not what to conclude about the loss of the stripes and spots. From the geographical distribution of the striped and unstriped species of Equus there seems to be something very mysterious about the loss of stripes; and I cannot persuade myself that the common ass has lost its stripes owing to being rendered more conspicuous from having stripes and thus exposed to danger. LETTER 433. TO J. JENNER WEIR. (433/1. Mr. John Jenner Weir, to whom the following letters are addressed, is frequently quoted in the "Descent of Man" as having supplied Mr. Darwin with information on a variety of subjects.) Down, February 27th [1868]. I must thank you for your paper on apterous lepidoptera (433/2. Published by the West Kent Natural History, Microscopical and Photographic Society, Greenwich, 1867. Mr. Weir's paper seems chiefly to have interested Mr. Darwin as affording a good case of gradation in the degree of degradation of the wings in various species.), which has interested me exceedingly, and likewise for the very honourable mention which you make of my name. It is almost a pity that your paper was not published in some Journal in which it would have had a wider distribution. It contained much that was new to me. I think the part about the relation of the wings and spiracles and tracheae might have been made a little clearer. Incidentally, you have done me a good service by reminding me of the rudimentary spurs on the legs of the partridge, for I am now writing on what I have called sexual selection. I believe that I am not mistaken in thinking that you have attended much to birds in confinement, as well as to insects. If you could call to mind any facts bearing on this subject, with birds, insects, or any animals--such as the selection by a female of any particular male--or conversely of a particular female by a male, or on the rivalry between males, or on the allurement of the females by the males, or any such facts, I should be most grateful for the information, if you would have the kindness to communicate it. P.S.--I may give as instance of [this] class of facts, that Barrow asserts that a male Emberiza (?) at the Cape has immensely long tail-feathers during the breeding season (433/3. Barrow describes the long tail feathers of Emberiza longicauda as enduring "but the season of love." "An Account of Travels into the Interior of Southern Africa": London, 1801, Volume I., page 244.); and that if these are cut off, he has no chance of getting a wife. I have always felt an intense wish to make analogous trials, but have never had an opportunity, and it is not likely that you or any one would be willing to try so troublesome an experiment. Colouring or staining the fine red breast of a bullfinch with some innocuous matter into a dingy tint would be an analogous case, and then putting him and ordinary males with a female. A friend promised, but failed, to try a converse experiment with white pigeons--viz., to stain their tails and wings with magenta or other colours, and then observe what effect such a prodigious alteration would have on their courtship. (433/4. See Letter 428.) It would be a fairer trial to cut off the eyes of the tail-feathers of male peacocks; but who would sacrifice the beauty of their bird for a whole season to please a mere naturalist? LETTER 434. TO J. JENNER WEIR. Down, February 29th [1868]. I have hardly ever received a note which has interested me more than your last; and this is no exaggeration. I had a few cases of birds perceiving slight changes in the dress of their owners, but your facts are of tenfold value. I shall certainly make use of them, and need not say how much obliged I should be for any others about which you feel confident. Do you know of any birds besides some of the gallinaceae which are polygamous? Do you know of any birds besides pigeons, and, as it is said, the raven, which pair for their whole lives? Many years ago I visited your brother, who showed me his pigeons and gave me some valuable information. Could you persuade him (but I fear he would think it high treason) to stain a male pigeon some brilliant colour, and observe whether it excited in the other pigeons, especially the females, admiration or contempt? For the chance of your liking to have a copy and being able to find some parts which would interest you, I have directed Mr. Murray to send you my recent book on "Variation under Domestication." P.S.--I have somewhere safe references to cases of magpies, of which one of a pair has been repeatedly (I think seven times) killed, and yet another mate was always immediately found. (434/1. On this subject see "Descent of Man," Edition I., Volume II., page 104, where Mr. Weir's observations were made use of. This statement is quoted from Jenner ("Phil. Trans." 1824) in the "Descent of Man" (1901), page 620.) A gamekeeper told me yesterday of analogous case. This perplexes me much. Are there many unmarried birds? I can hardly believe it. Or will one of a pair, of which the nest has been robbed, or which are barren, always desert his or her mate for a strange mate with the attraction of a nest, and in one instance with young birds in the nest? The gamekeeper said during breeding season he had never observed a single or unpaired partridge. How can the sexes be so equally matched? P.S. 2nd.--I fear you will find me a great bore, but I will be as reasonable as can be expected in plundering one so rich as you. P.S. 3rd.--I have just received a letter from Dr. Wallace (434/2. See "Descent of Man," Edition I., Volume I., pages 386-401, where Dr. Wallace's observations are quoted.), of Colchester, about the proportional numbers of the two sexes in Bombyx; and in this note, apropos to an incidental remark of mine, he stoutly maintains that female lepidoptera never notice the colours or appearance of the male, but always receive the first male which comes; and this appears very probable. He says he has often seen fine females receive old battered and pale-tinted males. I shall have to admit this very great objection to sexual selection in insects. His observations no doubt apply to English lepidoptera, in most of which the sexes are alike. The brimstone or orange-tip would be good to observe in this respect, but it is hopelessly difficult. I think I have often seen several males following one female; and what decides which male shall succeed? How is this about several males; is it not so? LETTER 435. TO J. JENNER WEIR. 6, Queen Anne Street, Cavendish Square, W. [March 6th, 1868]. I have come here for a few weeks, for a little change and rest. Just as I was leaving home I received your first note, and yesterday a second; and both are most interesting and valuable to me. That is a very curious observation about the goldfinch's beak (435/1. "Descent of Man," Edition I., Volume I., page 39. Mr. Weir is quoted as saying that the birdcatchers can distinguish the males of the goldfinch, Carduelis elegans, by their "slightly longer beaks."), but one would hardly like to trust it without measurement or comparison of the beaks of several male and female birds; for I do not understand that you yourself assert that the beak of the male is sensibly longer than that of the female. If you come across any acute birdcatchers (I do not mean to ask you to go after them), I wish you would ask what is their impression on the relative numbers of the sexes of any birds which they habitually catch, and whether some years males are more numerous and some years females. I see that I must trust to analogy (an unsafe support) for sexual selection in regard to colour in butterflies. You speak of the brimstone butterfly and genus Edusa (435/2. Colias Edusa.) (I forget what this is, and have no books here, unless it is Colias) not opening their wings. In one of my notes to Mr. Stainton I asked him (but he could or did not answer) whether butterflies such as the Fritillaries, with wings bright beneath and above, opened and shut their wings more than Vanessae, most of which, I think, are obscure on the under surface. That is a most curious observation about the red underwing moth and the robin (435/3. "Descent of Man," Edition I., Volume I., page 395. Mr. Weir describes the pursuit of a red-underwing, Triphoena pronuba, by a robin which was attracted by the bright colour of the moth, and constantly missed the insect by breaking pieces off the wing instead of seizing the body. Mr. Wallace's facts are given on the same page.), and strongly supports a suggestion (which I thought hardly credible) of A.R. Wallace, viz. that the immense wings of some exotic lepidoptera served as a protection from difficulty of birds seizing them. I will probably quote your case. No doubt Dr. Hooker collected the Kerguelen moth, for I remember he told me of the case when I suggested in the "Origin," the explanation of the coleoptera of Madeira being apterous; but he did not know what had become of the specimens. I am quite delighted to hear that you are observing coloured birds (435/4. "Descent of Man," Edition I., Volume II., page 110.), though the probability, I suppose, will be that no sure result will be gained. I am accustomed with my numerous experiments with plants to be well satisfied if I get any good result in one case out of five. You will not be able to read all my book--too much detail. Some of the chapters in the second volume are curious, I think. If any man wants to gain a good opinion of his fellow-men, he ought to do what I am doing, pester them with letters. LETTER 436. TO J. JENNER WEIR. 4, Chester Place, Regent's Park, N.W., March 13th [1868]. You make a very great mistake when you speak of "the risk of your notes boring me." They are of the utmost value to me, and I am sure I shall never be tired of receiving them; but I must not be unreasonable. I shall give almost all the facts which you have mentioned in your two last notes, as well as in the previous ones; and my only difficulty will be not to give too much and weary my readers. Your last note is especially valuable about birds displaying the beautiful parts of their plumage. Audubon (436/1. In his "Ornithological Biography," 5 volumes, Edinburgh, 1831-49.) gives a good many facts about the antics of birds during courtship, but nothing nearly so much to the purpose as yours. I shall never be able to resist giving the whole substance of your last note. It is quite a new light to me, except with the peacock and Bird of Paradise. I must now look to turkey's wings; but I do not think that their wings are beautiful when opened during courtship. Its tail is finely banded. How about the drake and Gallus bankiva? I forget how their wings look when expanded. Your facts are all the more valuable as I now clearly see that for butterflies I must trust to analogy altogether in regard to sexual selection. But I think I shall make out a strong case (as far as the rather deceitful guide of analogy will serve) in the sexes of butterflies being alike or differing greatly--in moths which do not display the lower surface of their wings not having them gaudily coloured, etc., etc.--nocturnal moths, etc.--and in some male insects fighting for the females, and attracting them by music. My discussion on sexual selection will be a curious one--a mere dovetailing of information derived from you, Bates, Wallace, etc., etc., etc. We remain at above address all this month, and then return home. In the summer, could I persuade you to pay us a visit of a day or two, and I would try and get Bates and some others to come down? But my health is so precarious, I can ask no one who will not allow me the privilege of a poor old invalid; for talking, I find by long and dear-bought experience, tries my head more than anything, and I am utterly incapable of talking more than half an hour, except on rare occasions. I fear this note is very badly written; but I was very ill all yesterday, and my hand shakes to-day. LETTER 437. TO J. JENNER WEIR. 4, Chester Place, Regent's Park, N.W., March 22nd [1868]. I hope that you will not think me ungrateful that I have not sooner answered your note of the 16th; but in fact I have been overwhelmed both with calls and letters; and, alas! one visit to the British Museum of an hour or hour and a half does for me for the whole day. I was particularly glad to hear your and your brother's statement about the "gay" deceiver-pigeons. (437/1. Some cock pigeons "called by our English fanciers gay birds are so successful in their gallantries that, as Mr. H. Weir informs me, they must be shut up, on account of the mischief which they cause.") I did not at all know that certain birds could win the affections of the females more than other males, except, indeed, in the case of the peacock. Conversely, Mr. Hewitt, I remember, states that in making hybrids the cock pheasant would prefer certain hen fowls and strongly dislike others. I will write to Mr. H. in a few days, and ask him whether he has observed anything of this kind with pure unions of fowls, ducks, etc. I had utterly forgotten the case of the ruff (437/2. The ruff, Machetes pugnax, was believed by Montague to be polygamous. "Descent of Man," Edition I., Volume I., page 270.), but now I remember having heard that it was polygamous; but polygamy with birds, at least, does not seem common enough to have played an important part. So little is known of habits of foreign birds: Wallace does not even know whether Birds of Paradise are polygamous. Have you been a large collector of caterpillars? I believe so. I inferred from a letter from Dr. Wallace, of Colchester, that he would account for Mr. Stainton and others rearing more female than male by their having collected the larger and finer caterpillars. But I misunderstood him, and he maintains that collectors take all caterpillars, large and small, for that they collect the caterpillars alone of the rarer moths or butterflies. What think you? I hear from Professor Canestrini (437/3. See "Descent of Man" (1901), page 385.) in Italy that females are born in considerable excess with Bombyx mori, and in greater excess of late years than formerly! Quatrefages writes to me that he believes they are equal in France. So that the farther I go the deeper I sink into the mire. With cordial thanks for your most valuable letters. We remain here till April 1st, and then hurrah for home and quiet work. LETTER 438. TO J. JENNER WEIR. 4, Chester Place, N.W., March 27th [1868]. I hardly know which of your three last letters has interested me most. What splendid work I shall have hereafter in selecting and arranging all your facts. Your last letter is most curious--all about the bird-catchers--and interested us all. I suppose the male chaffinch in "pegging" approaches the captive singing-bird, from rivalry or jealousy--if I am wrong please tell me; otherwise I will assume so. Can you form any theory about all the many cases which you have given me, and others which have been published, of when one [of a] pair is killed, another soon appearing? Your fact about the bullfinches in your garden is most curious on this head. (438/1. Mr. Weir stated that at Blackheath he never saw or heard a wild bullfinch, yet when one of his caged males died, a wild one in the course of a few days generally came and perched near the widowed female, whose call-note is not loud. "Descent of Man" (1901), page 623.) Are there everywhere many unpaired birds? What can the explanation be? Mr. Gould assures me that all the nightingales which first come over are males, and he believes this is so with other migratory birds. But this does not agree with what the bird-catchers say about the common linnet, which I suppose migrates within the limits of England. Many thanks for very curious case of Pavo nigripennis. (438/2. See "Animals and Plants," Edition II., Volume I., page 306.) I am very glad to get additional evidence. I have sent your fact to be inserted, if not too late, in four foreign editions which are now printing. I am delighted to hear that you approve of my book; I thought every mortal man would find the details very tedious, and have often repented of giving so many. You will find pangenesis stiff reading, and I fear will shake your head in disapproval. Wallace sticks up for the great god Pan like a man. The fertility of hybrid canaries would be a fine subject for careful investigation. LETTER 439. TO J. JENNER WEIR. Down, April 4th [1868]. I read over your last ten (!) letters this morning, and made an index of their contents for easy reference; and what a mine of wealth you have bestowed on me. I am glad you will publish yourself on gay-coloured caterpillars and birds (439/1. See "Descent of Man," Edition I., Volume I., page 417, where Mr. Weir's experiments are given; they were made to test Mr. Wallace's theory that caterpillars, which are protected against birds by an unpleasant taste, have been rendered conspicuous, so that they are easily recognised. They thus escape being pecked or tasted, which to soft-skinned animals would be as fatal as being devoured. See Mr. Jenner Weir's papers, "Transact. Entomolog. Soc." 1869, page 2; 1870, page 337. In regard to one of these papers Mr. Darwin wrote (May 13th, 1869): "Your verification of Wallace's suggestion seems to me to amount to quite a discovery."); it seems to me much the best plan; therefore, I will not forward your letter to Mr. Wallace. I was much in the Zoological Gardens during my month in London, and picked up what scraps of knowledge I could. Without my having mentioned your most interesting observations on the display of the Fringillidae (439/2. "Descent of Man" (1901), page 738.), Mr. Bartlett told me how the Gold Pheasant erects his collar and turns from side to side, displaying it to the hen. He has offered to give me notes on the display of all Gallinaceae with which he is acquainted; but he is so busy a man that I rather doubt whether he will ever do so. I received about a week ago a remarkably kind letter from your brother, and I am sorry to hear that he suffers much in health. He gave me some fine facts about a Dun Hen Carrier which would never pair with a bird of any other colour. He told me, also, of some one at Lewes who paints his dog! and will inquire about it. By the way, Mr. Trimen tells me that as a boy he used to paint butterflies, and that they long haunted the same place, but he made no further observations on them. As far as colour is concerned, I see I shall have to trust to mere inference from the males displaying their plumage, and other analogous facts. I shall get no direct evidence of the preference of the hens. Mr. Hewitt, of Birmingham, tells me that the common hen prefers a salacious cock, but is quite indifferent to colour. Will you consider and kindly give me your opinion on the two following points. Do very vigorous and well-nourished hens receive the male earlier in the spring than weaker or poorer hens? I suppose that they do. Secondly, do you suppose that the birds which pair first in the season have any advantage in rearing numerous and healthy offspring over those which pair later in the season? With respect to the mysterious cases of which you have given me so many, in addition to those previously collected, of when one bird of a pair is shot another immediately supplying its place, I was drawing to the conclusion that there must be in each district several unpaired birds; yet this seems very improbable. You allude, also, to the unknown causes which keep down the numbers of birds; and often and often have I marvelled over this subject with respect to many animals. LETTER 440. TO A.R. WALLACE. (440/1. The following refers to Mr. Wallace's article "A Theory of Birds' Nests," in Andrew Murray's "Journal of Travel," Volume I., page 73. He here treats in fuller detail the view already published in the "Westminster Review," July 1867, page 38. The rule which Mr. Wallace believes, with very few exceptions, to hold good is, "that when both sexes are of strikingly gay and conspicuous colours, the nest is...such as to conceal the sitting bird; while, whenever there is a striking contrast of colours, the male being gay and conspicuous, the female dull and obscure, the nest is open, and the sitting bird exposed to view." At this time Mr. Wallace allowed considerably more influence to sexual selection (in combination with the need of protection) than in his later writings. The following extract from a letter from Mr. Wallace to Darwin (July 23rd, 1877) fixes the period at which the change in his views occurred: "I am almost afraid to tell you that in going over the subject of the colours of animals, etc., etc., for a small volume of essays, etc., I am preparing, I have come to conclusions directly opposed to voluntary sexual selection, and believe that I can explain (in a general way) all the phenomena of sexual ornaments and colours by laws of development aided by simple 'Natural Selection.'" He finally rejected Mr. Darwin's theory that colours "have been developed by the preference of the females, the more ornamented males becoming the parents of each successive generation." "Darwinism," 1889, page 285. See also Letters 442, 443, 449, 450, etc.) Down, April 15th, [1868]. I have been deeply interested by your admirable article on birds' nests. I am delighted to see that we really differ very little,--not more than two men almost always will. You do not lay much or any stress on new characters spontaneously appearing in one sex (generally the male), and being transmitted exclusively, or more commonly only in excess, to that sex. I, on the other hand, formerly paid far too little attention to protection. I had only a glimpse of the truth; but even now I do not go quite as far as you. I cannot avoid thinking rather more than you do about the exceptions in nesting to the rule, especially the partial exceptions, i.e., when there is some little difference between the sexes in species which build concealed nests. I am not quite satisfied about the incubating males; there is so little difference in conspicuousness between the sexes. I wish with all my heart I could go the whole length with you. You seem to think that male birds probably select the most beautiful females; I must feel some doubt on this head, for I can find no evidence of it. Though I am writing so carping a note, I admire the article thoroughly. And now I want to ask a question. When female butterflies are more brilliant than their males you believe that they have in most cases, or in all cases, been rendered brilliant so as to mimic some other species, and thus escape danger. But can you account for the males not having been rendered equally brilliant and equally protected? (440/2. See Wallace in the "Westminster Review," July, 1867, page 37, on the protection to the female insect afforded by its resemblance either to an inanimate object or to another insect protected by its unpalatableness. The cases are discussed in relation to the much greater importance (to the species as a whole) of the preservation of the female insect with her load of eggs than the male who may safely be sacrificed after pairing. See Letter 189, note.) Although it may be most for the welfare of the species that the female should be protected, yet it would be some advantage, certainly no disadvantage, for the unfortunate male to enjoy an equal immunity from danger. For my part, I should say that the female alone had happened to vary in the right manner, and that the beneficial variations had been transmitted to the same sex alone. Believing in this, I can see no improbability (but from analogy of domestic animals a strong probability) that variations leading to beauty must often have occurred in the males alone, and been transmitted to that sex alone. Thus I should account in many cases for the greater beauty of the male over the female, without the need of the protective principle. I should be grateful for an answer on the point. LETTER 441. TO J. JENNER WEIR. Down, April 18th [1868]. You see that I have taken you at your word, and have not (owing to heaps of stupid letters) earlier noticed your three last letters, which as usual are rich in facts. Your letters make almost a little volume on my table. I daresay you hardly knew yourself how much curious information was lying in your mind till I began the severe pumping process. The case of the starling married thrice in one day is capital, and beats the case of the magpies of which one was shot seven times consecutively. A gamekeeper here tells me that he has repeatedly shot one of a pair of jays, and it has always been immediately replaced. I begin to think that the pairing of birds must be as delicate and tedious an operation as the pairing of young gentlemen and ladies. If I can convince myself that there are habitually many unpaired birds, it will be a great aid to me in sexual selection, about which I have lately had many troubles, and am therefore rejoiced to hear in your last note that your faith keeps staunch. That is a curious fact about the bullfinches all appearing to listen to the German singer (441/1. See Letter 445, note.); and this leads me to ask how much faith may I put in the statement that male birds will sing in rivalry until they injure themselves. Yarrell formerly told me that they would sometimes even sing themselves to death. I am sorry to hear that the painted bullfinch turns out to be a female; though she has done us a good turn in exhibiting her jealousy, of which I had no idea. Thank you for telling me about the wildness of the hybrid canaries: nothing has hardly ever surprised me more than the many cases of reversion from crossing. Do you not think it a very curious subject? I have not heard from Mr. Bartlett about the Gallinaceae, and I daresay I never shall. He told me about the Tragopan, and he is positive that the blue wattle becomes gorged with blood, and not air. Returning to the first of the last three letters. It is most curious the number of persons of the name of Jenner who have had a strong taste for Natural History. It is a pity you cannot trace your connection with the great Jenner, for a duke might be proud of his blood. I heard lately from Professor Rolleston of the inherited effects of an injury in the same eye. Is the scar on your son's leg on the same side and on exactly the same spot where you were wounded? And did the wound suppurate, or heal by the first intention? I cannot persuade myself of the truth of the common belief of the influence of the mother's imagination on the child. A point just occurs to me (though it does not at present concern me) about birds' nests. Have you read Wallace's recent articles? (441/2. A full discussion of Mr. Wallace's views is given in "Descent of Man," Edition I., Volume II., Chapter XV. Briefly, Mr. Wallace's point is that the dull colour of the female bird is protective by rendering her inconspicuous during incubation. Thus the relatively bright colour of the male would not simply depend on sexual selection, but also on the hen being "saved, through Natural Selection, from acquiring the conspicuous colours of the male" (loc. cit., page 155).) I always distrust myself when I differ from him; but I cannot admit that birds learn to make their nests from having seen them whilst young. I must think it as true an instinct as that which leads a caterpillar to suspend its cocoon in a particular manner. Have you had any experience of birds hatched under a foster-mother making their nests in the proper manner? I cannot thank you enough for all your kindness. LETTER 442. TO A.R. WALLACE. (442/1. Dr. Clifford Allbutt's view probably had reference to the fact that the sperm-cell goes, or is carried, to the germ-cell, never vice versa. In this letter Darwin gives the reason for the "law" referred to. Mr. A.R. Wallace has been good enough to give us the following note:--"It was at this time that my paper on 'Protective Resemblance' first appeared in the 'Westminster Review,' in which I adduced the greater, or rather, the more continuous, importance of the female (in the lower animals) for the race, and my 'Theory of Birds' Nests' ('Journal of Travel and Natural History,' No. 2) in which I applied this to the usually dull colours of female butterflies and birds. It is to these articles as well as to my letters that Darwin chiefly refers."--Note by Mr. Wallace, May 27th, 1902.) Down, April 30th [1868]. Your letter, like so many previous ones, has interested me much. Dr. Allbutt's view occurred to me some time ago, and I have written a short discussion on it. It is, I think, a remarkable law, to which I have found no exception. The foundation lies in the fact that in many cases the eggs or seeds require nourishment and protection by the mother-form for some time after impregnation. Hence the spermatozoa and antherozoids travel in the lower aquatic animals and plants to the female, and pollen is borne to the female organ. As organisms rise in the scale it seems natural that the male should carry the spermatozoa to the female in his own body. As the male is the searcher, he has required and gained more eager passions than the female; and, very differently from you, I look at this as one great difficulty in believing that the males select the more attractive females; as far as I can discover, they are always ready to seize on any female, and sometimes on many females. Nothing would please me more than to find evidence of males selecting the more attractive females. I have for months been trying to persuade myself of this. There is the case of man in favour of this belief, and I know in hybrid unions of males preferring particular females, but, alas, not guided by colour. Perhaps I may get more evidence as I wade through my twenty years' mass of notes. I am not shaken about the female protected butterflies. I will grant (only for argument) that the life of the male is of very little value,--I will grant that the males do not vary, yet why has not the protective beauty of the female been transferred by inheritance to the male? The beauty would be a gain to the male, as far as we can see, as a protection; and I cannot believe that it would be repulsive to the female as she became beautiful. But we shall never convince each other. I sometimes marvel how truth progresses, so difficult is it for one man to convince another, unless his mind is vacant. Nevertheless, I myself to a certain extent contradict my own remark, for I believe far more in the importance of protection than I did before reading your articles. I do not think you lay nearly stress enough in your articles on what you admit in your letters: viz., "there seems to be some production of vividness...of colour in the male independent of protection." This I am making a chief point; and have come to your conclusion so far that I believe that intense colouring in the female sex is often checked by being dangerous. That is an excellent remark of yours about no known case of male alone assuming protective colours; but in the cases in which protection has been gained by dull colours, I presume that sexual selection would interfere with the male losing his beauty. If the male alone had acquired beauty as a protection, it would be most readily overlooked, as males are so often more beautiful than their females. Moreover, I grant that the life of the male is somewhat less precious, and thus there would be less rigorous selection with the male, so he would be less likely to be made beautiful through Natural Selection for protection. (442/2. This does not apply to sexual selection, for the greater the excess of males, and the less precious their lives, so much the better for sexual selection. [Note in original.]) But it seems to me a good argument, and very good if it could be thoroughly established. I do not know whether you will care to read this scrawl. LETTER 443. TO A.R. WALLACE. Down, May 5th [1868?]. I am afraid I have caused you a great deal of trouble in writing to me at such length. I am glad to say that I agree almost entirely with your summary, except that I should put sexual selection as an equal, or perhaps as even a more important agent in giving colour than Natural Selection for protection. As I get on in my work I hope to get clearer and more decided ideas. Working up from the bottom of the scale, I have as yet only got to fishes. What I rather object to in your articles is that I do not think any one would infer from them that you place sexual selection even as high as No. 4 in your summary. It was very natural that you should give only a line to sexual selection in the summary to the "Westminster Review," but the result at first to my mind was that you attributed hardly anything to its power. In your penultimate note you say "in the great mass of cases in which there is great differentiation of colour between the sexes, I believe it is due almost wholly to the need of protection to the female." Now, looking to the whole animal kingdom, I can at present by no means admit this view; but pray do not suppose that because I differ to a certain extent, I do not thoroughly admire your several papers and your admirable generalisation on birds' nests. With respect to this latter point, however, although, following you, I suspect that I shall ultimately look at the whole case from a rather different point of view. You ask what I think about the gay-coloured females of Pieris. (443/1. See "Westminster Review," July, 1867, page 37; also Letter 440.) I believe I quite follow you in believing that the colours are wholly due to mimicry; and I further believe that the male is not brilliant from not having received through inheritance colour from the female, and from not himself having varied; in short, that he has not been influenced by selection. I can make no answer with respect to the elephants. With respect to the female reindeer, I have hitherto looked at the horns simply as the consequence of inheritance not having been limited by sex. Your idea about colour being concentrated in the smaller males seems good, and I presume that you will not object to my giving it as your suggestion. LETTER 444. TO J. JENNER WEIR. Down, May 7th [1868]. I have now to thank you for no less than four letters! You are so kind that I will not apologise for the trouble I cause you; but it has lately occurred to me that you ought to publish a paper or book on the habits of the birds which you have so carefully observed. But should you do this, I do not think that my giving some of the facts for a special object would much injure the novelty of your work. There is such a multitude of points in these last letters that I hardly know what to touch upon. Thanks about the instinct of nidification, and for your answers on many points. I am glad to hear reports about the ferocious female bullfinch. I hope you will have another try in colouring males. I have now finished lepidoptera, and have used your facts about caterpillars, and as a caution the case of the yellow-underwings. I have now begun on fishes, and by comparing different classes of facts my views are getting a little more decided. In about a fortnight or three weeks I shall come to birds, and then I dare say that I shall be extra troublesome. I will now enclose a few queries for the mere chance of your being able to answer some of them, and I think it will save you trouble if I write them on a separate slip, and then you can sometimes answer by a mere "no" or "yes." Your last letter on male pigeons and linnets has interested me much, for the precise facts which you have given me on display are of the utmost value for my work. I have written to Mr. Bartlett on Gallinaceae, but I dare say I shall not get an answer. I had heard before, but am glad to have confirmation about the ruffs being the most numerous. I am greatly obliged to your brother for sending out circulars. I have not heard from him as yet. I want to ask him whether he has ever observed when several male pigeons are courting one female that the latter decides with which male she will pair. The story about the black mark on the lambs must be a hoax. The inaccuracy of many persons is wonderful. I should like to tell you a story, but it is too long, about beans growing on the wrong side of the pod during certain years. Queries: Does any female bird regularly sing? Do you know any case of both sexes, more especially of the female, [being] more brightly coloured whilst young than when come to maturity and fit to breed? An imaginary instance would be if the female kingfisher (or male) became dull coloured when adult. Do you know whether the male and female wild canary bird differ in plumage (though I believe I could find this out for myself), and do any of the domestic breeds differ sexually? Do you know any gallinaceous bird in which the female has well developed spurs? It is very odd that my memory should fail me, but I cannot remember whether, in accordance with your views, the wing of Gallus bankiva (or Game-Cock, which is so like the wild) is ornamental when he opens and scrapes it before the female. I fear it is not; but though I have often looked at wing of the wild and tame bird, I cannot call to mind the exact colours. What a number of points you have attended to; I did not know that you were a horticulturist. I have often marvelled at the different growth of the flowering and creeping branches of the ivy; but had no idea that they kept their character when propagated by cuttings. There is a S. American genus (name forgotten just now) which differs in an analogous manner but even greater degree, but it is difficult to cultivate in our hot-house. I have tried and failed. LETTER 445. TO J. JENNER WEIR. Down, May 30th [1868]. I am glad to hear your opinion on the nest-making instinct, for I am Tory enough not to like to give up all old beliefs. Wallace's view (445/1. See Letter 440, etc.) is also opposed to a great mass of analogical facts. The cases which you mention of suddenly reacquired wildness seem curious. I have also to thank you for a previous valuable letter. With respect to spurs on female Gallinaceae, I applied to Mr. Blyth, who has wonderful systematic knowledge, and he tells me that the female Pavo muticus and Fire-back pheasants are spurred. From various interruptions I get on very slowly with my Bird MS., but have already often and often referred to your volume of letters, and have used various facts, and shall use many more. And now I am ashamed to say that I have more questions to ask; but I forget--you told me not to apologise. 1. In your letter of April 14th you mention the case of about twenty birds which seemed to listen with much interest to an excellent piping bullfinch. (445/2. Quoted in the "Descent of Man" (1901), page 564. "A bullfinch which had been taught to pipe a German waltz...when this bird was first introduced into a room where other birds were kept and he began to sing, all the others, consisting of about twenty linnets and canaries, ranged themselves on the nearest side of their cages, and listened with the greatest interest to the new performer.") What kind of birds were these twenty? 2. Is it true, as often stated, that a bird reared by foster-parents, and who has never heard the song of its own species, imitates to a certain extent the song of the species which it may be in the habit of hearing? Now for a more troublesome point. I find it very necessary to make out relation of immature plumage to adult plumage, both when the sexes differ and are alike in the adult state. Therefore, I want much to learn about the first plumage (answering, for instance, to the speckled state of the robin before it acquires the red breast) of the several varieties of the canary. Can you help me? What is the character or colour of the first plumage of bright yellow or mealy canaries which breed true to these tints? So with the mottled-brown canaries, for I believe that there are breeds which always come brown and mottled. Lastly, in the "prize-canaries," which have black wing- and tail-feathers during their first (?) plumage, what colours are the wings and tails after the first (?) moult or when adult? I should be particularly glad to learn this. Heaven have mercy on you, for it is clear that I have none. I am going to investigate this same point with all the breeds of fowls, as Mr. Tegetmeier will procure for me young birds, about two months old, of all the breeds. In the course of this next month I hope you will come down here on the Saturday and stay over the Sunday. Some months ago Mr. Bates said he would pay me a visit during June, and I have thought it would be pleasanter for you to come here when I can get him, so that you would have a companion if I get knocked up, as is sadly too often my bad habit and great misfortune. Did you ever hear of the existence of any sub-breed of the canary in which the male differs in plumage from the female? LETTER 446. TO F. MULLER. Down, June 3rd [1868]. Your letter of April 22nd has much interested me. I am delighted that you approve of my book, for I value your opinion more than that of almost any one. I have yet hopes that you will think well of pangenesis. I feel sure that our minds are somewhat alike, and I find it a great relief to have some definite, though hypothetical view, when I reflect on the wonderful transformations of animals, the re-growth of parts, and especially the direct action of pollen on the mother form, etc. It often appears to me almost certain that the characters of the parents are "photographed" on the child, only by means of material atoms derived from each cell in both parents, and developed in the child. I am sorry about the mistake in regard to Leptotes. (446/1. See "Animals and Plants," Edition I., Volume II., page 134, where it is stated that Oncidium is fertile with Leptotes, a mistake corrected in the 2nd edition.) I daresay it was my fault, yet I took pains to avoid such blunders. Many thanks for all the curious facts about the unequal number of the sexes in crustacea, but the more I investigate this subject the deeper I sink in doubt and difficulty. Thanks, also, for the confirmation of the rivalry of Cicadae. (446/2. See "Descent of Man," Edition I., Volume I., page 351, for F. Muller's observations; and for a reference to Landois' paper.) I have often reflected with surprise on the diversity of the means for producing music with insects, and still more with birds. We thus get a high idea of the importance of song in the animal kingdom. Please to tell me where I can find any account of the auditory organs in the orthoptera? Your facts are quite new to me. Scudder has described an annectant insect in Devonian strata, furnished with a stridulating apparatus. (446/3. The insect is no doubt Xenoneura antiquorum, from the Devonian rocks of New Brunswick. Scudder compared a peculiar feature in the wing of this species to the stridulating apparatus of the Locustariae, but afterwards stated that he had been led astray in his original description, and that there was no evidence in support of the comparison with a stridulating organ. See the "Devonian Insects of New Brunswick," reprinted in S.H. Scudder's "Fossil Insects of N. America," Volume I., page 179, New York, 1890.) I believe he is to be trusted, and if so the apparatus is of astonishing antiquity. After reading Landois' paper I have been working at the stridulating organ in the lamellicorn beetles, in expectation of finding it sexual, but I have only found it as yet in two cases, and in these it was equally developed in both sexes. I wish you would look at any of your common lamellicorns and take hold of both males and females and observe whether they make the squeaking or grating noise equally. If they do not, you could perhaps send me a male and female in a light little box. How curious it is that there should be a special organ for an object apparently so unimportant as squeaking. Here is another point: have you any Toucans? if so, ask any trustworthy hunter whether the beaks of the males, or of both sexes, are more brightly coloured during the breeding season than at other times of the year? I have also to thank you for a previous letter of April 3rd, with some interesting facts on the variation of maize, the sterility of Bignonia and on conspicuous seeds. Heaven knows whether I shall ever live to make use of half the valuable facts which you have communicated to me... LETTER 447. TO J. JENNER WEIR. Down, June 18th [1868]. Many thanks. I am glad that you mentioned the linnet, for I had much difficulty in persuading myself that the crimson breast could be due to change in the old feathers, as the books say. I am glad to hear of the retribution of the wicked old she-bullfinch. You remember telling me how many Weirs and Jenners have been naturalists; now this morning I have been putting together all my references about one bird of a pair being killed, and a new mate being soon found; you, Jenner Weir, have given me some most striking cases with starlings; Dr. Jenner gives the most curious case of all in "Philosophical Transactions" (447/1. "Phil. Trans." 1824.), and a Mr. Weir gives the next most striking in Macgillivray. (447/2. Macgillivray's "History of British Birds," Volume I., page 570. See "Descent of Man" (1901), page 621.) Now, is this not odd? Pray remember how very glad we shall be to see you here whenever you can come. Did some ancient progenitor of the Weirs and Jenners puzzle his brains about the mating of birds, and has the question become indelibly fixed in all your minds? LETTER 448. TO A.R. WALLACE. August 19th [1868]. I had become, before my nine weeks' horrid interruption of all work, extremely interested in sexual selection, and was making fair progress. In truth it has vexed me much to find that the farther I get on the more I differ from you about the females being dull-coloured for protection. I can now hardly express myself as strongly, even, as in the "Origin." This has much decreased the pleasure of my work. In the course of September, if I can get at all stronger, I hope to get Mr. J. Jenner Weir (who has been wonderfully kind in giving me information) to pay me a visit, and I will then write for the chance of your being able to come, and I hope bring with you Mrs. Wallace. If I could get several of you together it would be less dull for you, for of late I have found it impossible to talk with any human being for more than half an hour, except on extraordinary good days. (448/1. On September 16th Darwin wrote to Wallace on the same subject:--) You will be pleased to hear that I am undergoing severe distress about protection and sexual selection; this morning I oscillated with joy towards you; this evening I have swung back to the old position, out of which I fear I shall never get. LETTER 449. TO A.R. WALLACE. (449/1. From "Life and Letters," Volume III., page 123.) Down, September 23rd [1868]. I am very much obliged for all your trouble in writing me your long letter, which I will keep by me and ponder over. To answer it would require at least 200 folio pages! If you could see how often I have rewritten some pages you would know how anxious I am to arrive as near as I can to the truth. I lay great stress on what I know takes place under domestication; I think we start with different fundamental notions on inheritance. I find it is most difficult, but not, I think, impossible to see how, for instance, a few red feathers appearing on the head of a male bird, and which are at first transmitted to both sexes, would come to be transmitted to males alone. It is not enough that females should be produced from the males with red feathers, which should be destitute of red feathers; but these females must have a latent tendency to produce such feathers, otherwise they would cause deterioration in the red head-feathers of their male offspring. Such latent tendency would be shown by their producing the red feathers when old, or diseased in their ovaria. But I have no difficulty in making the whole head red if the few red feathers in the male from the first tended to be sexually transmitted. I am quite willing to admit that the female may have been modified, either at the same time or subsequently, for protection by the accumulation of variations limited in their transmission to the female sex. I owe to your writings the consideration of this latter point. But I cannot yet persuade myself that females alone have often been modified for protection. Should you grudge the trouble briefly to tell me, whether you believe that the plainer head and less bright colours of female chaffinch, the less red on the head and less clean colours of female goldfinch, the much less red on the breast of the female bullfinch, the paler crest of golden-crested wren, etc., have been acquired by them for protection? I cannot think so, any more than I can that the considerable differences between female and male house-sparrow, or much greater brightness of male Parus caeruleus (both of which build under cover) than of female Parus, are related to protection. I even misdoubt much whether the less blackness of female blackbird is for protection. Again, can you give me reasons for believing that the moderate differences between the female pheasant, the female Gallus bankiva, the female of black grouse, the pea-hen, the female partridge, have all special references to protection under slightly different conditions? I, of course, admit that they are all protected by dull colours, derived, as I think, from some dull-ground progenitor; and I account partly for their difference by partial transference of colour from the male, and by other means too long to specify; but I earnestly wish to see reason to believe that each is specially adapted for concealment to its environment. I grieve to differ from you, and it actually terrifies me and makes me constantly distrust myself. I fear we shall never quite understand each other. I value the cases of bright-coloured, incubating male fisher, and brilliant female butterflies, solely as showing that one sex may be made brilliant without any necessary transference of beauty to the other sex; for in these cases I cannot suppose that beauty in the other sex was checked by selection. I fear this letter will trouble you to read it. A very short answer about your belief in regard to the female finches and Gallinaceae would suffice. LETTER 450. A.R. WALLACE TO CHARLES DARWIN. 9, St. Mark's Crescent, N.W., September 27th, 1868. Your view seems to be that variations occurring in one sex are transmitted either to that sex exclusively or to both sexes equally, or more rarely partially transferred. But we have every gradation of sexual colours, from total dissimilarity to perfect identity. If this is explained solely by the laws of inheritance, then the colours of one or other sex will be always (in relation to the environment) a matter of chance. I cannot think this. I think selection more powerful than laws of inheritance, of which it makes use, as shown by cases of two, three or four forms of female butterflies, all of which have, I have little doubt, been specialised for protection. To answer your first question is most difficult, if not impossible, because we have no sufficient evidence in individual cases of slight sexual difference, to determine whether the male alone has acquired his superior brightness by sexual selection, or the female been made duller by need of protection, or whether the two causes have acted. Many of the sexual differences of existing species may be inherited differences from parent forms, which existed under different conditions and had greater or less need of protection. I think I admitted before, the general tendency (probably) of males to acquire brighter tints. Yet this cannot be universal, for many female birds and quadrupeds have equally bright tints. To your second question I can reply more decidedly. I do think the females of the Gallinaceae you mention have been modified or been prevented from acquiring the brighter plumage of the male, by need of protection. I know that the Gallus bankiva frequents drier and more open situations than the pea-hen of Java, which is found among grassy and leafy vegetation, corresponding with the colours of the two. So the Argus pheasant, male and female, are, I feel sure, protected by their tints corresponding to the dead leaves of the lofty forest in which they dwell, and the female of the gorgeous fire-back pheasant Lophura viellottii is of a very similar rich brown colour. I do not, however, at all think the question can be settled by individual cases, but by only large masses of facts. The colours of the mass of female birds seem to me strictly analogous to the colours of both sexes of snipes, woodcocks, plovers, etc., which are undoubtedly protective. Now, supposing, on your view, that the colours of a male bird become more and more brilliant by sexual selection, and a good deal of that colour is transmitted to the female till it becomes positively injurious to her during incubation, and the race is in danger of extinction; do you not think that all the females who had acquired less of the male's bright colours, or who themselves varied in a protective direction, would be preserved, and that thus a good protective colouring would soon be acquired? If you admit that this could occur, and can show no good reason why it should not often occur, then we no longer differ, for this is the main point of my view. Have you ever thought of the red wax-tips of the Bombycilla beautifully imitating the red fructification of lichens used in the nest, and therefore the FEMALES have it too? Yet this is a very sexual-looking character. If sexes have been differentiated entirely by sexual selection the females can have no relation to environment. But in groups when both sexes require protection during feeding or repose, as snipes, woodcock, ptarmigan, desert birds and animals, green forest birds, etc., arctic birds of prey, and animals, then both sexes are modified for protection. Why should that power entirely cease to act when sexual differentiation exists and when the female requires protection, and why should the colour of so many FEMALE BIRDS seem to be protective, if it has not been made protective by selection. It is contrary to the principles of "Origin of Species," that colour should have been produced in both sexes by sexual selection and never have been modified to bring the female into harmony with the environment. "Sexual selection is less rigorous than Natural Selection," and will therefore be subordinate to it. I think the case of female Pieris pyrrha proves that females alone can be greatly modified for protection. (450/1. My latest views on this subject, with many new facts and arguments, will be found in the later editions of my "Darwinism," Chapter X. (A.R.W.)) LETTER 451. A.R. WALLACE TO CHARLES DARWIN. (451/1. On October 4th, 1868, Mr. Wallace wrote again on the same subject without adding anything of importance to his arguments of September 27th. We give his final remarks:--) October 4th, 1868. I am sorry to find that our difference of opinion on this point is a source of anxiety to you. Pray do not let it be so. The truth will come out at last, and our difference may be the means of setting others to work who may set us both right. After all, this question is only an episode (though an important one) in the great question of the "Origin of Species," and whether you or I are right will not at all affect the main doctrine--that is one comfort. I hope you will publish your treatise on "Sexual Selection" as a separate book as soon as possible; and then, while you are going on with your other work, there will no doubt be found some one to battle with me over your facts on this hard problem. LETTER 452. TO A.R. WALLACE. Down, October 6th [1868]. Your letter is very valuable to me, and in every way very kind. I will not inflict a long answer, but only answer your queries. There are breeds (viz. Hamburg) in which both sexes differ much from each other and from both sexes of Gallus bankiva; and both sexes are kept constant by selection. The comb of the Spanish male has been ordered to be upright, and that of Spanish female to lop over, and this has been effected. There are sub-breeds of game fowl, with females very distinct and males almost identical; but this, apparently, is the result of spontaneous variation, without special selection. I am very glad to hear of case of female Birds of Paradise. I have never in the least doubted possibility of modifying female birds alone for protection, and I have long believed it for butterflies. I have wanted only evidence for the female alone of birds having had their colour modified for protection. But then I believe that the variations by which a female bird or butterfly could get or has got protective colouring have probably from the first been variations limited in their transmission to the female sex. And so with the variations of the male: when the male is more beautiful than the female, I believe the variations were sexually limited in their transmission to the males. LETTER 453. TO B.D. WALSH. Down, October 31st, 1868. (453/1. A short account of the Periodical Cicada (C. septendecim) is given by Dr. Sharp in the Cambridge Natural History, Insects II., page 570. We are indebted to Dr. Sharp for calling our attention to Mr. C.L. Marlatt's full account of the insect in "Bulletin No. 14 [NS.] of the U.S. Department of Agriculture," 1898. The Cicada lives for long periods underground as larva and pupa, so that swarms of the adults of one race (septendecim) appear at intervals of 17 years, while those of the southern form or race (tredecim) appear at intervals of 13 years. This fact was first made out by Phares in 1845, but was overlooked or forgotten, and was only re-discovered by Walsh and Riley in 1868, who published a joint paper in the "American Entomologist," Volume I., page 63. Walsh appears to have adhered to the view that the 13- and 17-year forms are distinct species, though, as we gather from Marlatt's paper (page 14), he published a letter to Mr. Darwin in which he speaks of the 13-year form as an incipient species; see "Index to Missouri Entomolog. Reports Bull. 6," U.S.E.C., page 58 (as given by Marlatt). With regard to the cause of the difference in period of the two forms, Marlatt (pages 15, 16) refers doubtfully to difference of temperature as the determining factor. Experiments have been instituted by moving 17-year eggs to the south, and vice versa with 13-year eggs. The results were, however, not known at the time of publication of Marlatt's paper.) I am very much obliged for the extracts about the "drumming," which will be of real use to me. I do not at all know what to think of your extraordinary case of the Cicadas. Professor Asa Gray and Dr. Hooker were staying here, and I told them of the facts. They thought that the 13-year and the 17-year forms ought not to be ranked as distinct species, unless other differences besides the period of development could be discovered. They thought the mere rarity of variability in such a point was not sufficient, and I think I concur with them. The fact of both the forms presenting the same case of dimorphism is very curious. I have long wished that some one would dissect the forms of the male stag-beetle with smaller mandibles, and see if they were well developed, i.e., whether there was an abundance of spermatozoa; and the same observations ought, I think, to be made on the rarer form of your Cicada. Could you not get some observer, such as Dr. Hartman (453/2. Mr. Walsh sent Mr. Darwin an extract from Dr. Hartman's "Journal of the doings of a Cicada septendecim," in which the females are described as flocking round the drumming males. "Descent of Man" (1901), page 433.), to note whether the females flocked in equal numbers to the "drumming" of the rarer form as to the common form? You have a very curious and perplexing subject of investigation, and I wish you success in your work. LETTER 454. TO A.R. WALLACE. Down, June 15th [1869?]. You must not suppose from my delay that I have not been much interested by your long letter. I write now merely to thank you, and just to say that probably you are right on all the points you touch on, except, as I think, about sexual selection, which I will not give up. My belief in it, however, is contingent on my general belief in sexual selection. It is an awful stretcher to believe that a peacock's tail was thus formed; but, believing it, I believe in the same principle somewhat modified applied to man. LETTER 455. TO G.H.K. THWAITES. Down, February 13th [N.D.] I wrote a little time ago asking you an odd question about elephants, and now I am going to ask you an odder. I hope that you will not think me an intolerable bore. It is most improbable that you could get me an answer, but I ask on mere chance. Macacus silenus (455/1. Macacus silenus L., an Indian ape.) has a great mane of hair round neck, and passing into large whiskers and beard. Now what I want most especially to know is whether these monkeys, when they fight in confinement (and I have seen it stated that they are sometimes kept in confinement), are protected from bites by this mane and beard. Any one who watched them fighting would, I think, be able to judge on this head. My object is to find out with various animals how far the mane is of any use, or a mere ornament. Is the male Macacus silenus furnished with longer hair than the female about the neck and face? As I said, it is a hundred or a thousand to one against your finding out any one who has kept these monkeys in confinement. LETTER 456. TO F. MULLER. Down, August 28th [1870]. I have to thank you very sincerely for two letters: one of April 25th, containing a very curious account of the structure and morphology of Bonatea. I feel that it is quite a sin that your letters should not all be published! but, in truth, I have no spare strength to undertake any extra work, which, though slight, would follow from seeing your letters in English through the press--not but that you write almost as clearly as any Englishman. This same letter also contained some seeds for Mr. Farrer, which he was very glad to receive. Your second letter, of July 5th, was chiefly devoted to mimicry in lepidoptera: many of your remarks seem to me so good, that I have forwarded your letter to Mr. Bates; but he is out of London having his summer holiday, and I have not yet heard from him. Your remark about imitators and imitated being of such different sizes, and the lower surface of the wings not being altered in colour, strike me as the most curious points. I should not be at all surprised if your suggestion about sexual selection were to prove true; but it seems rather too speculative to be introduced in my book, more especially as my book is already far too speculative. The very same difficulty about brightly coloured caterpillars had occurred to me, and you will see in my book what, I believe, is the true explanation from Wallace. The same view probably applies in part to gaudy butterflies. My MS. is sent to the printers, and, I suppose, will be published in about three months: of course I will send you a copy. By the way, I settled with Murray recently with respect to your book (456/1. The translation of "Fur Darwin," published in 1869.), and had to pay him only 21 pounds 2 shillings 3 pence, which I consider a very small price for the dissemination of your views; he has 547 copies as yet unsold. This most terrible war will stop all science in France and Germany for a long time. I have heard from nobody in Germany, and know not whether your brother, Hackel, Gegenbaur, Victor Carus, or my other friends are serving in the army. Dohrn has joined a cavalry regiment. I have not yet met a soul in England who does not rejoice in the splendid triumph of Germany over France (456/2. See Letter 239, Volume I.): it is a most just retribution against that vainglorious, war-liking nation. As the posts are all in confusion, I will not send this letter through France. The Editor has sent me duplicate copies of the "Revue des Cours Scientifiques," which contain several articles about my views; so I send you copies for the chance of your liking to see them. LETTER 457. A.R. WALLACE TO CHARLES DARWIN. Holly House, Barking, E., January 27th, 1871. Many thanks for your first volume (457/1. "The Descent of Man".), which I have just finished reading through with the greatest pleasure and interest; and I have also to thank you for the great tenderness with which you have treated me and my heresies. On the subject of "sexual selection" and "protection," you do not yet convince me that I am wrong; but I expect your heaviest artillery will be brought up in your second volume, and I may have to capitulate. You seem, however, to have somewhat misunderstood my exact meaning, and I do not think the difference between us is quite so great as you seem to think it. There are a number of passages in which you argue against the view that the female has in any large number of cases been "specially modified" for protection, or that colour has generally been obtained by either sex for purposes of protection. But my view is, as I thought I had made it clear, that the female has (in most cases) been simply prevented from acquiring the gay tints of the male (even when there was a tendency for her to inherit it), because it was hurtful; and that, when protection is not needed, gay colours are so generally acquired by both sexes as to show that inheritance by both sexes of colour variations is the most usual, when not prevented from acting by Natural Selection. The colour itself may be acquired either by sexual selection or by other unknown causes. There are, however, difficulties in the very wide application you give to sexual selection which at present stagger me, though no one was or is more ready than myself to admit the perfect truth of the principle or the immense importance and great variety of its applications. Your chapters on "Man" are of intense interest--but as touching my special heresy, not as yet altogether convincing, though, of course, I fully agree with every word and every argument which goes to prove the "evolution" or "development" of man out of a lower form. My ONLY difficulties are, as to whether you have accounted for EVERY STEP of the development by ascertained laws. I feel sure that the book will keep up and increase your high reputation, and be immensely successful, as it deserves to be... LETTER 458. TO G.B. MURDOCH. Down, March 13th, 1871. (458/1. We are indebted to Mr. Murdoch for a draft of his letter dated March 10th, 1871. It is too long to be quoted at length; the following citations give some idea of its contents: "In your 'Descent of Man,' in treating of the external differences between males and females of the same variety, have you attached sufficient importance to the different amount and kind of energy expended by them in reproduction?" Mr. Murdoch sums up: "Is it wrong, then, to suppose that extra growth, complicated structure, and activity in one sex exist as escape-valves for surplus vigour, rather than to please or fight with, though they may serve these purposes and be modified by them?") I am much obliged for your valuable letter. I am strongly inclined to think that I have made a great and complete oversight with respect to the subject which you discuss. I am the more surprised at this, as I remember reflecting on some points which ought to have led me to your conclusion. By an odd chance I received the day before yesterday a letter from Mr. Lowne (author of an excellent book on the anatomy of the Blow-fly) (458/2. "The Anatomy and Physiology of the Blow-fly (Musca vomitaria L.)," by B.T. Lowne. London, 1870.) with a discussion very nearly to the same effect as yours. His conclusions were drawn from studying male insects with great horns, mandibles, etc. He informs me that his paper on this subject will soon be published in the "Transact. Entomolog. Society." (458/3. "Observations on Immature Sexuality and Alternate Generation in Insects." By B.T. Lowne. "Trans. Entomolog. Soc." 1871 [Read March 6th, 1871]. "I believe that certain cutaneous appendages, as the gigantic mandibles and thoracic horns of many males, are complemental to the sexual organs; that, in point of fact, they are produced by the excess of nutriment in the male, which in the female would go to form the generative organs and ova" (loc. cit., page 197).) I am inclined to look at your and Mr. Lowne's view as specially valuable from probably throwing light on the greater variability of male than female animals, which manifestly has much bearing on sexual selection. I will keep your remarks in mind whenever a new edition of my book is demanded. LETTER 459. TO GEORGE FRASER. (459/1. The following letter refers to two letters to Mr. Darwin, in which Mr. Fraser pointed out that illustrations of the theory of Sexual Selection might be found amongst British butterflies and moths. Mr. Fraser, in explanation of the letters, writes: "As an altogether unknown and far from experienced naturalist, I feared to send my letters for publication without, in the first place, obtaining Mr. Darwin's approval." The information was published in "Nature," Volume III., April 20th, 1871, page 489. The article was referred to in the second edition of the "Descent of Man" (1874), pages 312, 316, 319. Mr. Fraser adds: "This is only another illustration of Mr. Darwin's great conscientiousness in acknowledging suggestions received by him from the most humble sources." (Letter from Mr. Fraser to F. Darwin, March 21, 1888.) Down, April 14th [1871]. I am very much obliged for your letter and the interesting facts which it contains, and which are new to me. But I am at present so much engaged with other subjects that I cannot fully consider them; and, even if I had time, I do not suppose that I should have anything to say worth printing in a scientific journal. It would obviously be absurd in me to allow a mere note of thanks from me to be printed. Whenever I have to bring out a corrected edition of my book I will well consider your remarks (which I hope that you will send to "Nature"), but the difficulty will be that my friends tell me that I have already introduced too many facts, and that I ought to prune rather than to introduce more. LETTER 460. TO E.S. MORSE. Down, December 3rd, 1871. I am much obliged to you for having sent me your two interesting papers, and for the kind writing on the cover. I am very glad to have my error corrected about the protective colouring of shells. (460/1. "On Adaptive Coloration of the Mollusca," "Boston Society of Natural History Proc." Volume XIV., April 5th, 1871. Mr. Morse quotes from the "Descent of Man," I., page 316, a passage to the effect that the colours of the mollusca do not in general appear to be protective. Mr. Morse goes on to give instances of protective coloration.) It is no excuse for my broad statement, but I had in my mind the species which are brightly or beautifully coloured, and I can as yet hardly think that the colouring in such cases is protective. LETTER 461. TO AUG. WEISMANN. Down, February 29th, 1872. I am rejoiced to hear that your eyesight is somewhat better; but I fear that work with the microscope is still out of your power. I have often thought with sincere sympathy how much you must have suffered from your grand line of embryological research having been stopped. It was very good of you to use your eyes in writing to me. I have just received your essay (461/1. "Ueber der Einfluss der Isolirung auf die Artbildung": Leipzig, 1872.); but as I am now staying in London for the sake of rest, and as German is at all times very difficult to me, I shall not be able to read your essay for some little time. I am, however, very curious to learn what you have to say on isolation and on periods of variation. I thought much about isolation when I wrote in Chapter IV. on the circumstances favourable to Natural Selection. No doubt there remains an immense deal of work to do on "Artbildung." I have only opened a path for others to enter, and in the course of time to make a broad and clear high-road. I am especially glad that you are turning your attention to sexual selection. I have in this country hardly found any naturalists who agree with me on this subject, even to a moderate extent. They think it absurd that a female bird should be able to appreciate the splendid plumage of the male; but it would take much to persuade me that the peacock does not spread his gorgeous tail in the presence of the female in order to fascinate or excite her. The case, no doubt, is much more difficult with insects. I fear that you will find it difficult to experiment on diurnal lepidoptera in confinement, for I have never heard of any of these breeding in this state. (461/2. We are indebted to Mr. Bateson for the following note: "This belief does not seem to be well founded, for since Darwin's time several species of Rhopalocera (e.g. Pieris, Pararge, Caenonympha) have been successfully bred in confinement without any special difficulty; and by the use of large cages members even of strong-flying genera, such as Vanessa, have been induced to breed.") I was extremely pleased at hearing from Fritz Muller that he liked my chapter on lepidoptera in the "Descent of Man" more than any other part, excepting the chapter on morals. LETTER 462. TO H. MULLER. Down [May, 1872]. I have now read with the greatest interest your essay, which contains a vast amount of matter quite new to me. (462/1. "Anwendung der Darwin'schen Lehre auf Bienen," "Verhandl. d. naturhist. Vereins fur preuss. Rheinld. u. Westf." 1872. References to Muller's paper occur in the second edition of the "Descent of Man.") I really have no criticisms or suggestions to offer. The perfection of the gradation in the character of bees, especially in such important parts as the mouth-organs, was altogether unknown to me. You bring out all such facts very clearly by your comparison with the corresponding organs in the allied hymenoptera. How very curious is the case of bees and wasps having acquired, independently of inheritance from a common source, the habit of building hexagonal cells and of producing sterile workers! But I have been most interested by your discussion on secondary sexual differences; I do not suppose so full an account of such differences in any other group of animals has ever been published. It delights me to find that we have independently arrived at almost exactly the same conclusion with respect to the more important points deserving investigation in relation to sexual selection. For instance, the relative number of the two sexes, the earlier emergence of the males, the laws of inheritance, etc. What an admirable illustration you give of the transference of characters acquired by one sex--namely, that of the male of Bombus possessing the pollen-collecting apparatus. Many of your facts about the differences between male and female bees are surprisingly parallel with those which occur with birds. The reading your essay has given me great confidence in the efficacy of sexual selection, and I wanted some encouragement, as extremely few naturalists in England seem inclined to believe in it. I am, however, glad to find that Prof. Weismann has some faith in this principle. The males of Bombus follow one remarkable habit, which I think it would interest you to investigate this coming summer, and no one could do it better than you. (462/2. Mr. Darwin's observations on this curious subject were sent to Hermann Muller, and after his death were translated and published in Krause's "Gesammelte kleinere Schriften von Charles Darwin," 1887, page 84. The male bees had certain regular lines of flight at Down, as from the end of the kitchen garden to the corner of the "sand-walk," and certain regular "buzzing places" where they stopped on the wing for a moment or two. Mr. Darwin's children remember vividly the pleasure of helping in the investigation of this habit.) I have therefore enclosed a briefly and roughly drawn-up account of this habit. Should you succeed in making any observations on this subject, and if you would like to use in any way my MS. you are perfectly welcome. I could, should you hereafter wish to make any use of the facts, give them in rather fuller detail; but I think that I have given enough. I hope that you may long have health, leisure, and inclination to do much more work as excellent as your recent essay. 2.VIII.III. EXPRESSION, 1868-1874. LETTER 463. TO F. MULLER. Down, January 30th [1868]. I am very much obliged for your answers, though few in number (October 5th), about expression. I was especially glad to hear about shrugging the shoulders. You say that an old negro woman, when expressing astonishment, wonderfully resembled a Cebus when astonished; but are you sure that the Cebus opened its mouth? I ask because the Chimpanzee does not open its mouth when astonished, or when listening. (463/1. Darwin in the "Expression of the Emotions," adheres to this statement as being true of monkeys in general.) Please have the kindness to remember that I am very anxious to know whether any monkey, when screaming violently, partially or wholly closes its eyes. LETTER 464. TO W. BOWMAN. (464/1. The late Sir W. Bowman, the well-known surgeon, supplied a good deal of information of value to Darwin in regard to the expression of the emotions. The gorging of the eyes with blood during screaming is an important factor in the physiology of weeping, and indirectly in the obliquity of the eyebrows--a characteristic expression of suffering. See "Expression of the Emotions," pages 160 and 192.) Down, March 30th [1868]. I called at your house about three weeks since, and heard that you were away for the whole month, which I much regretted, as I wished to have had the pleasure of seeing you, of asking you a question, and of thanking you for your kindness to my son George. You did not quite understand the last note which I wrote to you--viz., about Bell's precise statement that the conjunctiva of an infant or young child becomes gorged with blood when the eyes are forcibly opened during a screaming fit. (464/2. Sir C. Bell's statement in his "Anatomy of Expression" (1844, page 106) is quoted in the "Expression of the Emotions," page 158.) I have carefully kept your previous note, in which you spoke doubtfully about Bell's statement. I intended in my former note only to express a wish that if, during your professional work, you were led to open the eyelids of a screaming child, you would specially observe this point about the eye showing signs of becoming gorged with blood, which interests me extremely. Could you ask any one to observe this for me in an eye-dispensary or hospital? But I now have to beg you kindly to consider one other question at any time when you have half an hour's leisure. When a man coughs violently from choking or retches violently, even when he yawns, and when he laughs violently, tears come into the eyes. Now, in all these cases I observe that the orbicularis muscle is more or less spasmodically contracted, as also in the crying of a child. So, again, when the muscles of the abdomen contract violently in a propelling manner, and the breath is, I think, always held, as during the evacuation of a very costive man, and as (I hear) with a woman during severe labour-pains, the orbicularis contracts, and tears come into the eyes. Sir J.E. Tennant states that tears roll down the cheeks of elephants when screaming and trumpeting at first being captured; accordingly I went to the Zoological Gardens, and the keeper made two elephants trumpet, and when they did this violently the orbicularis was invariably plainly contracted. Hence I am led to conclude that there must be some relation between the contraction of this muscle and the secretion of tears. Can you tell me what this relation is? Does the orbicularis press against, and so directly stimulate, the lachrymal gland? As a slight blow on the eye causes, by reflex action, a copious effusion of tears, can the slight spasmodic contraction of the orbicularis act like a blow? This seems hardly possible. Does the same nerve which runs to the orbicularis send off fibrils to the lachrymal glands; and if so, when the order goes for the muscle to contract, is nervous force sent sympathetically at the same time to the glands? (464/3. See "Expression of the Emotions," page 169.) I should be extremely much obliged if you [would] have the kindness to give me your opinion on this point. LETTER 465. TO F.C. DONDERS. (465/1. Mr. Darwin was indebted to Sir W. Bowman for an introduction to Professor Donders, whose work on Sir Charles Bell's views is quoted in the "Expression of the Emotions," pages 160-62.) Down, June 3rd [1870?]. I do not know how to thank you enough for the very great trouble which you have taken in writing at such length, and for your kind expressions towards me. I am particularly obliged for the abstract with respect to Sir C. Bell's views (465/2. See "Expression of the Emotions," pages 158 et seq.: Sir Charles Bell's view is that adopted by Darwin--viz. that the contraction of the muscles round the eyes counteracts the gorging of the parts during screaming, etc. The essay of Donders is, no doubt, "On the Action of the Eyelids in Determination of Blood from Expiratory Effort" in Beale's "Archives of Medicine," Volume V., 1870, page 20, which is a translation of the original in Dutch.), as I shall now proceed with some confidence; but I am intensely curious to read your essay in full when translated and published, as I hope, in the "Dublin Journal," as you speak of the weak point in the case--viz., that injuries are not known to follow from the gorging of the eye with blood. I may mention that my son and his friend at a military academy tell me that when they perform certain feats with their heads downwards their faces become purple and veins distended, and that they then feel an uncomfortable sensation in their eyes; but that as it is necessary for them to see, they cannot protect their eyes by closing the eyelids. The companions of one young man, who naturally has very prominent eyes, used to laugh at him when performing such feats, and declare that some day both eyes would start out of his head. Your essay on the physiological and anatomical relations between the contraction of the orbicular muscles and the secretion of tears is wonderfully clear, and has interested me greatly. I had not thought about irritating substances getting into the nose during vomiting; but my clear impression is that mere retching causes tears. I will, however, try to get this point ascertained. When I reflect that in vomiting (subject to the above doubt), in violent coughing from choking, in yawning, violent laughter, in the violent downward action of the abdominal muscle...and in your very curious case of the spasms (465/3. In some cases a slight touch to the eye causes spasms of the orbicularis muscle, which may continue for so long as an hour, being accompanied by a flow of tears. See "Expression of the Emotions," page 166.)--that in all these cases the orbicular muscles are strongly and unconsciously contracted, and that at the same time tears often certainly flow, I must think that there is a connection of some kind between these phenomena; but you have clearly shown me that the nature of the relation is at present quite obscure. LETTER 466. TO A.D. BARTLETT. 6, Queen Anne Street, W., December 19th [1870?]. I was with Mr. Wood this morning, and he expressed himself strongly about your and your daughter's kindness in aiding him. He much wants assistance on another point, and if you would aid him, you would greatly oblige me. You know well the appearance of a dog when approaching another dog with hostile intentions, before they come close together. The dog walks very stiffly, with tail rigid and upright, hair on back erected, ears pointed and eyes directed forwards. When the dog attacks the other, down go the ears, and the canines are uncovered. Now, could you anyhow arrange so that one of your dogs could see a strange dog from a little distance, so that Mr. Wood could sketch the former attitude, viz., of the stiff gesture with erected hair and erected ears. (466/1. In Chapter II. of the "Expression of the Emotions" there are sketches of dogs in illustration of the "Principle of Antithesis," drawn by Mr. Riviere and by Mr. A. May (figures 5-8). Mr. T.W. Wood supplied similar drawings of a cat (figures 9, 10), also a sketch of the head of a snarling dog (figure 14).) And then he could afterwards sketch the same dog, when fondled by his master and wagging his tail with drooping ears. These two sketches I want much, and it would be a great favour to Mr. Wood, and myself, if you could aid him. P.S.--When a horse is turned out into a field he trots with high, elastic steps, and carries his tail aloft. Even when a cow frisks about she throws up her tail. I have seen a drawing of an elephant, apparently trotting with high steps, and with the tail erect. When the elephants in the garden are turned out and are excited so as to move quickly, do they carry their tails aloft? How is this with the rhinoceros? Do not trouble yourself to answer this, but I shall be in London in a couple of months, and then perhaps you will be able to answer this trifling question. Or, if you write about wolves and jackals turning round, you can tell me about the tails of elephants, or of any other animals. (466/2. In the "Expression of the Emotions," page 44, reference is made under the head of "Associated habitual movements in the lower animals," to dogs and other animals turning round and round and scratching the ground with their fore-paws when they wish to go to sleep on a carpet, or other similar surface.) LETTER 467. TO A.D. BARTLETT. Down, January 5th, [1871?] Many thanks about Limulus. I am going to ask another favour, but I do not want to trouble you to answer it by letter. When the Callithrix sciureus screams violently, does it wrinkle up the skin round the eyes like a baby always does? (467/1. "Humboldt also asserts that the eyes of the Callithrix sciureus 'instantly fill with tears when it is seized with fear'; but when this pretty little monkey in the Zoological Gardens was teased, so as to cry out loudly, this did not occur. I do not, however, wish to throw the least doubt on the accuracy of Humboldt's statement." ("The Expression of the Emotions in Man and Animals," 1872, page 137.) When thus screaming do the eyes become suffused with moisture? Will you ask Sutton to observe carefully? (467/2. One of the keepers who made many observations on monkeys for Mr. Darwin.) Could you make it scream without hurting it much? I should be truly obliged some time for this information, when in spring I come to the Gardens. LETTER 468. TO W. OGLE. Down, March 7th [1871]. I wrote to Tyndall, but had no clear answer, and have now written to him again about odours. (468/1. Dr. Ogle's work on the Sense of Smell ("Medico-Chirurgical Trans." LIII., page 268) is referred to in the "Expression of the Emotions," page 256.) I write now to ask you to be so kind (if there is no objection) to tell me the circumstances under which you saw a man arrested for murder. (468/2. Given in the "Expression of the Emotions," page 294.) I say in my notes made from your conversation: utmost horror--extreme pallor--mouth relaxed and open--general prostration--perspiration--muscle of face contracted--hair observed on account of having been dyed, and apparently not erected. Secondly, may I quote you that you have often (?) seen persons (young or old? men or women?) who, evincing no great fear, were about to undergo severe operation under chloroform, showing resignation by (alternately?) folding one open hand over the other on the lower part of chest (whilst recumbent?)--I know this expression, and think I ought to notice it. Could you look out for an additional instance? I fear you will think me very troublesome, especially when I remind you (not that I am in a hurry) about the Eustachian tube. LETTER 469. TO J. JENNER WEIR. Down, June 14th [1870]. As usual, I am going to beg for information. Can you tell me whether any Fringillidae or Sylviadae erect their feathers when frightened or enraged? (469/1. See "Expression of the Emotions," page 99.) I want to show that this expression is common to all or most of the families of birds. I know of this only in the fowl, swan, tropic-bird, owl, ruff and reeve, and cuckoo. I fancy that I remember having seen nestling birds erect their feathers greatly when looking into nests, as is said to be the case with young cuckoos. I should much like to know whether nestlings do really thus erect their feathers. I am now at work on expression in animals of all kinds, and birds; and if you have any hints I should be very glad for them, and you have a rich wealth of facts of all kinds. Any cases like the following: the sheldrake pats or dances on the tidal sands to make the sea-worms come out; and when Mr. St. John's tame sheldrakes came to ask for their dinners they used to pat the ground, and this I should call an expression of hunger and impatience. How about the Quagga case? (469/2. See Letter 235, Volume I.) I am working away as hard as I can on my book; but good heavens, how slow my progress is. LETTER 470. TO F.C. DONDERS. Down, March 18th, 1871. Very many thanks for your kind letter. I have been interested by what you tell me about your views published in 1848, and I wish I could read your essay. It is clear to me that you were as near as possible in preceding me on the subject of Natural Selection. You will find very little that is new to you in my last book; whatever merit it may possess consists in the grouping of the facts and in deductions from them. I am now at work on my essay on Expression. My last book fatigued me much, and I have had much correspondence, otherwise I should have written to you long ago, as I often intended to tell you in how high a degree your essay published in Beale's Archives interested me. (470/1. Beale's "Archives of Medicine," Volume V., 1870.) I have heard others express their admiration at the complete manner in which you have treated the subject. Your confirmation of Sir C. Bell's rather loose statement has been of paramount importance for my work. (470/2. On the contraction of the muscles surrounding the eye. See "Expression of the Emotions," page 158. See Letters 464, 465.) You told me that I might make further enquiries from you. When a person is lost in meditation his eyes often appear as if fixed on a distant object (470/3. The appearance is due to divergence of the lines of vision produced by muscular relaxation. See "Expression of the Emotions," Edition II., page 239.), and the lower eyelids may be seen to contract and become wrinkled. I suppose the idea is quite fanciful, but as you say that the eyeball advances in adaptation for vision for close objects, would the eyeball have to be pushed backwards in adaptation for distant objects? (470/4. Darwin seems to have misunderstood a remark of Donders.) If so, can the wrinkling of the lower eyelids, which has often perplexed me, act in pushing back the eyeball? But, as I have said, I daresay this is quite fanciful. Gratiolet says that the pupil contracts in rage, and dilates enormously in terror. (470/5. See "Expression of the Emotions," Edition II., page 321.) I have not found this great anatomist quite trustworthy on such points, and am making enquiries on this subject. But I am inclined to believe him, as the old Scotch anatomist Munro says, that the iris of parrots contracts and dilates under passions, independently of the amount of light. Can you give any explanation of this statement? When the heart beats hard and quick, and the head becomes somewhat congested with blood in any illness, does the pupil contract? Does the pupil dilate in incipient faintness, or in utter prostration, as when after a severe race a man is pallid, bathed in perspiration, with all his muscles quivering? Or in extreme prostration from any illness? LETTER 471. TO W. TURNER. Down, March 28th [1871]. I am much obliged for your kind note, and especially for your offer of sending me some time corrections, for which I shall be truly grateful. I know that there are many blunders to which I am very liable. There is a terrible one confusing the supra-condyloid foramen with another one. (471/1. In the first edition of the "Descent of Man," I., page 28, in quoting Mr. Busk "On the Caves of Gibraltar," Mr. Darwin confuses together the inter-condyloid foramen in the humerus with the supra-condyloid foramen. His attention was called to the mistake by Sir William Turner, to whom he had been previously indebted for other information on the anatomy of man. The error is one, as Sir William Turner points out in a letter, "which might easily arise where the writer is not minutely acquainted with human anatomy." In speaking of his correspondence with Darwin, Sir William remarks on a characteristic of Darwin's method of asking for information, namely, his care in avoiding leading questions.) This, however, I have corrected in all the copies struck off after the first lot of 2500. I daresay there will be a new edition in the course of nine months or a year, and this I will correct as well as I can. As yet the publishers have kept up type, and grumble dreadfully if I make heavy corrections. I am very far from surprised that "you have not committed yourself to full acceptation" of the evolution of man. Difficulties and objections there undoubtedly are, enough and to spare, to stagger any cautious man who has much knowledge like yourself. I am now at work at my hobby-horse essay on Expression, and I have been reading some old notes of yours. In one you say it is easy to see that the spines of the hedgehog are moved by the voluntary panniculus. Now, can you tell me whether each spine has likewise an oblique unstriped or striped muscle, as figured by Lister? (472/2. "Expression of the Emotions," page 101.) Do you know whether the tail-coverts of peacock or tail of turkey are erected by unstriped or striped muscles, and whether these are homologous with the panniculus or with the single oblique unstriped muscles going to each separate hair in man and many animals? I wrote some time ago to Kolliker to ask this question (and in relation to quills of porcupine), and I received a long and interesting letter, but he could not answer these questions. If I do not receive any answer (for I know how busy you must be), I will understand you cannot aid me. I heard yesterday that Paget was very ill; I hope this is not true. What a loss he would be; he is so charming a man. P.S.--As I am writing I will trouble you with one other question. Have you seen anything or read of any facts which could induce you to think that the mind being intently and long directed to any portion of the skin (or, indeed, any organ) would influence the action of the capillaries, causing them either to contract or dilate? Any information on this head would be of great value to me, as bearing on blushing. If I remember right, Paget seems to be a great believer in the influence of the mind in the nutrition of parts, and even in causing disease. It is awfully audacious on my part, but I remember thinking (with respect to the latter assertion on disease) when I read the passage that it seemed rather fanciful, though I should like to believe in it. Sir H. Holland alludes to this subject of the influence of the mind on local circulation frequently, but gives no clear evidence. (472/3. Ibid., pages 339 et seq.) LETTER 472. TO W. TURNER. Down, March 29th [1871]. Forgive me for troubling you with one line. Since writing my P.S. I have read the part on the influence of the nervous system on the nutrition of parts in your last edition of Paget's "Lectures." (472/1. "Lectures on Surgical Pathology," Edition III., revised by Professor Turner, 1870.) I had not read before this part in this edition, and I see how foolish I was. But still, I should be extremely grateful for any hint or evidence of the influence of mental attention on the capillary or local circulation of the skin, or of any part to which the mind may be intently and long directed. For instance, if thinking intently about a local eruption on the skin (not on the face, for shame might possibly intervene) caused it temporarily to redden, or thinking of a tumour caused it to throb, independently of increased heart action. LETTER 473. TO HUBERT AIRY. (473/1. Dr. Airy had written to Mr. Darwin on April 3rd:-- "With regard to the loss of voluntary movement of the ears in man and monkey, may I ask if you do not think it might have been caused, as it is certainly compensated, by the facility and quickness in turning the head, possessed by them in virtue of their more erect stature, and the freedom of the atlanto-axial articulation? (in birds the same end is gained by the length and flexibility of the neck.) The importance, in case of danger, of bringing the eyes to help the ears would call for a quick turn of the head whenever a new sound was heard, and so would tend to make superfluous any special means of moving the ears, except in the case of quadrupeds and the like, that have great trouble (comparatively speaking) in making a horizontal turn of the head--can only do it by a slow bend of the whole neck." (473/2. We are indebted to Dr. Airy for furnishing us with a copy of his letter to Mr. Darwin, the original of which had been mislaid.) Down, April 5th [1871]. I am greatly obliged for your letter. Your idea about the easy turning of the head instead of the ears themselves strikes me as very good, and quite new to me, and I will keep it in mind; but I fear that there are some cases opposed to the notion. If I remember right the hedgehog has very human ears, but birds support your view, though lizards are opposed to it. Several persons have pointed out my error about the platysma. (473/3. The error in question occurs on page 19 of the "Descent of Man," Edition I., where it is stated that the Platysma myoides cannot be voluntarily brought into action. In the "Expression of the Emotions" Darwin remarks that this muscle is sometimes said not to be under voluntary control, and he shows that this is not universally true.) Nor can I remember how I was misled. I find I can act on this muscle myself, now that I know the corners of the mouth have to be drawn back. I know of the case of a man who can act on this muscle on one side, but not on the other; yet he asserts positively that both contract when he is startled. And this leads me to ask you to be so kind as to observe, if any opportunity should occur, whether the platysma contracts during extreme terror, as before an operation; and secondly, whether it contracts during a shivering fit. Several persons are observing for me, but I receive most discordant results. I beg you to present my most respectful and kind compliments to your honoured father [Sir G.B. Airy]. LETTER 474. TO FRANCIS GALTON. (474/1. Mr. Galton had written on November 7th, 1872, offering to send to various parts of Africa Darwin's printed list of questions intended to guide observers on expression. Mr. Galton goes on: "You do not, I think, mention in "Expression" what I thought was universal among blubbering children (when not trying to see if harm or help was coming out of the corner of one eye) of pressing the knuckles against the eyeballs, thereby reinforcing the orbicularis.") Down, November 8th [1872]. Many thanks for your note and offer to send out the queries; but my career is so nearly closed that I do not think it worth while. What little more I can do shall be chiefly new work. I ought to have thought of crying children rubbing their eyes with their knuckles, but I did not think of it, and cannot explain it. As far as my memory serves, they do not do so whilst roaring, in which case compression would be of use. I think it is at the close of the crying fit, as if they wished to stop their eyes crying, or possibly to relieve the irritation from the salt tears. I wish I knew more about the knuckles and crying. What a tremendous stir-up your excellent article on prayer has made in England and America! (474/2. The article entitled "Statistical Inquiries into the Efficacy of Prayer" appeared in the "Fortnightly Review," 1872. In Mr. Francis Galton's book on "Enquiries into Human Faculty and its Development," London, 1883, a section (pages 277-94) is devoted to a discussion on the "Objective Efficacy of Prayer.") LETTER 475. TO F.C. DONDERS. (475/1. We have no means of knowing whether the observations suggested in the following letter were made--if not, the suggestion is worthy of record.) Down, December 21st, 1872. You will have received some little time ago my book on Expression, in writing which I was so deeply indebted to your kindness. I want now to beg a favour of you, if you have the means to grant it. A clergyman, the head of an institution for the blind in England (475/2. The Rev. R.H. Blair, Principal of the Worcester College: "Expression of the Emotions," Edition II., page 237.), has been observing the expression of those born blind, and he informs me that they never or very rarely frown. He kept a record of several cases, but at last observed a frown on two of the children who he thought never frowned; and then in a foolish manner tore up his notes, and did not write to me until my book was published. He may be a bad observer and altogether mistaken, but I think it would be worth while to ascertain whether those born blind, when young, and whilst screaming violently, contract the muscles round the eyes like ordinary infants. And secondly, whether in after years they rarely or never frown. If it should prove true that infants born blind do not contract their orbicular muscles whilst screaming (though I can hardly believe it) it would be interesting to know whether they shed tears as copiously as other children. The nature of the affection which causes blindness may possibly influence the contraction of the muscles, but on all such points you will judge infinitely better than I can. Perhaps you could get some trustworthy superintendent of an asylum for the blind to attend to this subject. I am sure that you will forgive me asking this favour. LETTER 476. TO D. HACK TUKE. Down, December 22nd, 1872. I have now finished your book, and have read it with great interest. (476/1. "Influence of the Mind upon the Body. Designed to elucidate the Power of the Imagination." 1872.) Many of your cases are very striking. As I felt sure would be the case, I have learnt much from it; and I should have modified several passages in my book on Expression, if I had had the advantage of reading your work before my publication. I always felt, and said so a year ago to Professor Donders, that I had not sufficient knowledge of Physiology to treat my subject in a proper way. With many thanks for the interest which I have felt in reading your work... LETTER 477. TO A.R. WALLACE. Down, January 10th [1873]. I have read your Review with much interest, and I thank you sincerely for the very kind spirit in which it is written. I cannot say that I am convinced by your criticisms. (477/1. "Quarterly Journal of Science," January, 1873, page 116: "I can hardly believe that when a cat, lying on a shawl or other soft material, pats or pounds it with its feet, or sometimes sucks a piece of it, it is the persistence of the habit of pressing the mammary glands and sucking during kittenhood." Mr. Wallace goes on to say that infantine habits are generally completely lost in adult life, and that it seems unlikely that they should persist in a few isolated instances.) If you have ever actually observed a kitten sucking and pounding, with extended toes, its mother, and then seen the same kitten when a little older doing the same thing on a soft shawl, and ultimately an old cat (as I have seen), and do not admit that it is identically the same action, I am astonished. With respect to the decapitated frog, I have always heard of Pfluger as a most trustworthy observer. (477/2. Mr. Wallace speaks of "a readiness to accept the most marvellous conclusions or interpretations of physiologists on what seem very insufficient grounds," and he goes on to assert that the frog experiment is either incorrectly recorded or else that it "demonstrates volition, and not reflex action.") If, indeed, any one knows a frog's habits so well as to say that it never rubs off a bit of leaf or other object which may stick to its thigh, in the same manner as it did the acid, your objection would be valid. Some of Flourens' experiments, in which he removed the cerebral hemispheres from a pigeon, indicate that acts apparently performed consciously can be done without consciousness. I presume through the force of habit, in which case it would appear that intellectual power is not brought into play. Several persons have made suggestions and objections as yours about the hands being held up in astonishment; if there was any straining of the muscles, as with protruded arms under fright, I would agree; as it is I must keep to my old opinion, and I dare say you will say that I am an obstinate old blockhead. (477/3. The raising of the hands in surprise is explained ("Expression of Emotions," Edition I., page 287) on the doctrine of antithesis as being the opposite of listlessness. Mr. Wallace's view (given in the 2nd edition of "Expression of the Emotions," page 300) is that the gesture is appropriate to sudden defence or to the giving of aid to another person.) The book has sold wonderfully; 9,000 copies have now been printed. LETTER 478. TO CHAUNCEY WRIGHT. Down, September 21st, 1874. I have read your long letter with the greatest interest, and it was extremely kind of you to take such great trouble. Now that you call my attention to the fact, I well know the appearance of persons moving the head from side to side when critically viewing any object; and I am almost sure that I have seen the same gesture in an affected person when speaking in exaggerated terms of some beautiful object not present. I should think your explanation of this gesture was the true one. But there seems to me a rather wide difference between inclining or moving the head laterally, and moving it in the same plane, as we do in negation, and, as you truly add, in disapprobation. It may, however, be that these two movements of the head have been confounded by travellers when speaking of the Turks. Perhaps Prof. Lowell would remember whether the movement was identically the same. Your remarks on the effects of viewing a sunset, etc., with the head inverted are very curious. (478/1. The letter dated September 3rd, 1874, is published in Mr. Thayer's "Letters" of Chauncey Wright, privately printed, Cambridge, Mass., 1878. Wright quotes Mr. Sophocles, a native of Greece, at the time Professor of Modern and Ancient Greek at Harvard University, to the effect that the Turks do not express affirmation by a shake of the head, but by a bow or grave nod, negation being expressed by a backward nod. From the striking effect produced by looking at a landscape with the head inverted, or by looking at its reflection, Chauncey Wright was led to the lateral movement of the head, which is characteristic of critical inspection--eg. of a picture. He thinks that in this way a gesture of deliberative assent arose which may have been confused with our ordinary sign of negation. He thus attempts to account for the contradictions between Lieber's statement that a Turk or Greek expresses "yes" by a shake of the head, and the opposite opinion of Prof. Sophocles, and lastly, Mr. Lowell's assertion that in Italy our negative shake of the head is used in affirmation (see "Expression of the Emotions," Edition II., page 289).) We have a looking-glass in the drawing-room opposite the flower-garden, and I have often been struck how extremely pretty and strange the flower garden and surrounding bushes appear when thus viewed. Your letter will be very useful to me for a new edition of my Expression book; but this will not be for a long time, if ever, as the publisher was misled by the very large sale at first, and printed far too many copies. I daresay you intend to publish your views in some essay, and I think you ought to do so, for you might make an interesting and instructive discussion. I have been half killing myself of late with microscopical work on plants. I begin to think that they are more wonderful than animals. P.S., January 29th, 1875.--You will see that by a stupid mistake in the address this letter has just been returned to me. It is by no means worth forwarding, but I cannot bear that you should think me so ungracious and ungrateful as not to have thanked you for your long letter. As I forget whether "Cambridge" is sufficient address, I will send this through Asa Gray. (PLATE: CHARLES LYELL. Engraved by G.I. (J). Stodart from a photograph.) CHAPTER 2.IX. GEOLOGY, 1840-1882. I. Vulcanicity and Earth-movements.--II. Ice-action.--III. The Parallel Roads of Glen Roy.--IV. Coral Reefs, Fossil and Recent.--V. Cleavage and Foliation.--VI. Age of the World.--VII. Geological Action of Earthworms.--VIII. Miscellaneous. 2.IX.I. VULCANICITY AND EARTH-MOVEMENTS, 1840-1881. LETTER 479. TO DAVID MILNE. 12, Upper Gower Street, Thursday [March] 20th [1840]. I much regret that I am unable to give you any information of the kind you desire. You must have misunderstood Mr. Lyell concerning the object of my paper. (479/1. "On the Connexion of certain Volcanic Phenomena, and on the Formation of Mountain-chains and the Effects of Continental Elevations." "Trans. Geol. Soc." Volume V., 1840, pages 601-32 [March 7th, 1838].) It is an account of the shock of February, 1835, in Chile, which is particularly interesting, as it ties most closely together volcanic eruptions and continental elevations. In that paper I notice a very remarkable coincidence in volcanic eruptions in S. America at very distant places. I have also drawn up some short tables showing, as it appears to me, that there are periods of unusually great volcanic activity affecting large portions of S. America. I have no record of any coincidences between shocks there and in Europe. Humboldt, by his table in the "Pers. Narrative" (Volume IV., page 36, English Translation), seems to consider the elevation of Sabrina off the Azores as connected with S. American subterranean activity: this connection appears to be exceedingly vague. I have during the past year seen it stated that a severe shock in the northern parts of S. America coincided with one in Kamstchatka. Believing, then, that such coincidences are purely accidental, I neglected to take a note of the reference; but I believe the statement was somewhere in "L'Institut" for 1839. (479/2. "L'Institut, Journal General des Societes et Travaux Scientifiques de la France et de l'Etranger," Tome VIII. page 412, Paris, 1840. In a note on some earthquakes in the province Maurienne it is stated that they occurred during a change in the weather, and at times when a south wind followed a north wind, etc.) I was myself anxious to see the list of the 1200 shocks alluded to by you, but I have not been able to find out that the list has been published. With respect to any coincidences you may discover between shocks in S. America and Europe, let me venture to suggest to you that it is probably a quite accurate statement that scarcely one hour in the year elapses in S. America without an accompanying shock in some part of that large continent. There are many regions in which earthquakes take place every three and four days; and after the severer shocks the ground trembles almost half-hourly for months. If, therefore, you had a list of the earthquakes of two or three of these districts, it is almost certain that some of them would coincide with those in Scotland, without any other connection than mere chance. My paper will be published immediately in the "Geological Transactions," and I will do myself the pleasure of sending you a copy in the course of (as I hope) a week or ten days. A large part of it is theoretical, and will be of little interest to you; but the account of the Concepcion shock of 1835 will, I think, be worth your perusal. I have understood from Mr. Lyell that you believe in some connection between the state of the weather and earthquakes. Under the very peculiar climate of Northern Chile, the belief of the inhabitants in such connection can hardly, in my opinion, be founded in error. It must possibly be worth your while to turn to pages 430-433 in my "Journal of Researches during the Voyage of the 'Beagle'," where I have stated this circumstance. (479/3. "Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of H.M.S. 'Beagle' round the World." London, 1870, page 351.) On the hypothesis of the crust of the earth resting on fluid matter, would the influence of the moon (as indexed by the tides) affect the periods of the shocks, when the force which causes them is just balanced by the resistance of the solid crust? The fact you mention of the coincidence between the earthquakes of Calabria and Scotland appears most curious. Your paper will possess a high degree of interest to all geologists. I fancied that such uniformity of action, as seems here indicated, was probably confined to large continents, such as the Americas. How interesting a record of volcanic phenomena in Iceland would be, now that you are collecting accounts of every slight trembling in Scotland. I am astonished at their frequency in that quiet country, as any one would have called it. I wish it had been in my power to have contributed in any way to your researches on this most interesting subject. LETTER 480. TO L. HORNER. Down, August 29th [1844]. I am greatly obliged for your kind note, and much pleased with its contents. If one-third of what you say be really true, and not the verdict of a partial judge (as from pleasant experience I much suspect), then should I be thoroughly well contented with my small volume which, small as it is, cost me much time. (480/1. "Geological Observations on the Volcanic Islands visited during the Voyage of H.M.S. 'Beagle'": London, 1844. A French translation has been made by Professor Renard of Ghent, and published by Reinwald of Paris in 1902.) The pleasure of observation amply repays itself: not so that of composition; and it requires the hope of some small degree of utility in the end to make up for the drudgery of altering bad English into sometimes a little better and sometimes worse. With respect to craters of elevation (480/2. "Geological Observations," pages 93-6.), I had no sooner printed off the few pages on that subject than I wished the whole erased. I utterly disbelieve in Von Buch and de Beaumont's views; but on the other hand, in the case of the Mauritius and St. Jago, I cannot, perhaps unphilosophically, persuade myself that they are merely the basal fragments of ordinary volcanoes; and therefore I thought I would suggest the notion of a slow circumferential elevation, the central part being left unelevated, owing to the force from below being spent and [relieved?] in eruptions. On this view, I do not consider these so-called craters of elevation as formed by the ejection of ashes, lava, etc., etc., but by a peculiar kind of elevation acting round and modified by a volcanic orifice. I wish I had left it all out; I trust that there are in other parts of the volume more facts and less theory. The more I reflect on volcanoes, the more I appreciate the importance of E. de Beaumont's measurements (480/3. Elie de Beaumont's views are discussed by Sir Charles Lyell both in the "Principles of Geology" (Edition X., 1867, Volume I. pages 633 et seq.) and in the "Elements of Geology" (Edition III., 1878, pages 495, 496). See also Darwin's "Geological Observations," Edition II., 1876, page 107.) (even if one does not believe them implicitly) of the natural inclination of lava-streams, and even more the importance of his view of the dikes, or unfilled fissures, in every volcanic mountain, being the proofs and measures of the stretching and consequent elevation which all such mountains must have undergone. I believe he thus unintentionally explains most of his cases of lava-streams being inclined at a greater angle than that at which they could have flowed. But excuse this lengthy note, and once more let me thank you for the pleasure and encouragement you have given me--which, together with Lyell's never-failing kindness, will help me on with South America, and, as my books will not sell, I sometimes want such aid. I have been lately reading with care A. d'Orbigny's work on South America (480/4. "Voyage dans l'Amerique Meridionale--execute pendant les annees 1826-33": six volumes, Paris, 1835-43.), and I cannot say how forcibly impressed I am with the infinite superiority of the Lyellian school of Geology over the continental. I always feel as if my books came half out of Lyell's brain, and that I never acknowledge this sufficiently; nor do I know how I can without saying so in so many words--for I have always thought that the great merit of the "Principles" was that it altered the whole tone of one's mind, and therefore that, when seeing a thing never seen by Lyell, one yet saw it partially through his eyes--it would have been in some respects better if I had done this less: but again excuse my long, and perhaps you will think presumptuous, discussion. Enclosed is a note from Emma to Mrs. Horner, to beg you, if you can, to give us the great pleasure of seeing you here. We are necessarily dull here, and can offer no amusements; but the weather is delightful, and if you could see how brightly the sun now shines you would be tempted to come. Pray remember me most kindly to all your family, and beg of them to accept our proposal, and give us the pleasure of seeing them. LETTER 481. TO C. LYELL. Down, [September, 1844]. I was glad to get your note, and wanted to hear about your work. I have been looking to see it advertised; it has been a long task. I had, before your return from Scotland, determined to come up and see you; but as I had nothing else to do in town, my courage has gradually eased off, more especially as I have not been very well lately. We get so many invitations here that we are grown quite dissipated, but my stomach has stood it so ill that we are going to have a month's holidays, and go nowhere. The subject which I was most anxious to talk over with you I have settled, and having written sixty pages of my "S. American Geology," I am in pretty good heart, and am determined to have very little theory and only short descriptions. The two first chapters will, I think, be pretty good, on the great gravel terraces and plains of Patagonia and Chili and Peru. I am astonished and grieved over D'Orbigny's nonsense of sudden elevations. (481/1. D'Orbigny's views are referred to by Lyell in chapter vii. of the "Principles," Volume I. page 131. "This mud [i.e. the Pampean mud] contains in it recent species of shells, some of them proper to brackish water, and is believed by Mr. Darwin to be an estuary or delta deposit. M.A. D'Orbigny, however, has advanced an hypothesis...that the agitation and displacement of the waters of the ocean, caused by the elevation of the Andes, gave rise to a deluge, of which this Pampean mud, which reaches sometimes the height of 12,000 feet, is the result and monument.") I must give you one of his cases: He finds an old beach 600 feet above sea. He finds STILL ATTACHED to the rocks at 300 feet six species of truly littoral shells. He finds at 20 to 30 feet above sea an immense accumulation of chiefly littoral shells. He argues the whole 600 feet uplifted at one blow, because the attached shells at 300 feet have not been displaced. Therefore when the sea formed a beach at 600 feet the present littoral shells were attached to rocks at 300 feet depth, and these same shells were accumulating by thousands at 600 feet. Hear this, oh Forbes. Is it not monstrous for a professed conchologist? This is a fair specimen of his reasoning. One of his arguments against the Pampas being a slow deposit, is that mammifers are very seldom washed by rivers into the sea! Because at 12,000 feet he finds the same kind of clay with that of the Pampas he never doubts that it is contemporaneous with the Pampas [debacle?] which accompanied the right royal salute of every volcano in the Cordillera. What a pity these Frenchmen do not catch hold of a comet, and return to the good old geological dramas of Burnett and Whiston. I shall keep out of controversy, and just give my own facts. It is enough to disgust one with Geology; though I have been much pleased with the frank, decided, though courteous manner with which D'Orbigny disputes my conclusions, given, unfortunately, without facts, and sometimes rashly, in my journal. Enough of S. America. I wish you would ask Mr. Horner (for I forgot to do so, and am unwilling to trouble him again) whether he thinks there is too much detail (quite independent of the merits of the book) in my volcanic volume; as to know this would be of some real use to me. You could tell me when we meet after York, when I will come to town. I had intended being at York, but my courage has failed. I should much like to hear your lecture, but still more to read it, as I think reading is always better than hearing. I am very glad you talk of a visit to us in the autumn if you can spare the time. I shall be truly glad to see Mrs. Lyell and yourself here; but I have scruples in asking any one--you know how dull we are here. Young Hooker (481/2. Sir J.D. Hooker.) talks of coming; I wish he might meet you,--he appears to me a most engaging young man. I have been delighted with Prescott, of which I have read Volume I. at your recommendation; I have just been a good deal interested with W. Taylor's (of Norwich) "Life and Correspondence." On your return from York I shall expect a great supply of Geological gossip. LETTER 482. TO C. LYELL. [October 3rd, 1846.] I have been much interested with Ramsay, but have no particular suggestions to offer (482/1. "On the Denudation of South Wales and the Adjacent Counties of England." A.C. Ramsay, "Mem. Geol. Survey Great Britain," Volume I., London, 1846.); I agree with all your remarks made the other day. My final impression is that the only argument against him is to tell him to read and re-read the "Principles," and if not then convinced to send him to Pluto. Not but what he has well read the "Principles!" and largely profited thereby. I know not how carefully you have read this paper, but I think you did not mention to me that he does (page 327) (482/2. Ramsay refers the great outlines of the country to the action of the sea in Tertiary times. In speaking of the denudation of the coast, he says: "Taking UNLIMITED time into account, we can conceive that any extent of land might be so destroyed...If to this be added an EXCEEDINGLY SLOW DEPRESSION of the land and sea bottom, the wasting process would be materially assisted by this depression" (loc. cit., page 327).) believe that the main part of his great denudation was effected during a vast (almost gratuitously assumed) slow Tertiary subsidence and subsequent Tertiary oscillating slow elevation. So our high cliff argument is inapplicable. He seems to think his great subsidence only FAVOURABLE for great denudation. I believe from the general nature of the off-shore sea's bottoms that it is almost necessary; do look at two pages--page 25 of my S. American volume--on this subject. (482/3. "Geological Observations on S. America," 1846, page 25. "When viewing the sea-worn cliffs of Patagonia, in some parts between 800 and 900 feet in height, and formed of horizontal Tertiary strata, which must once have extended far seaward...a difficulty often occurred to me, namely, how the strata could possibly have been removed by the action of the sea at a considerable depth beneath its surface." The cliffs of St. Helena are referred to in illustration of the same problem; speaking of these, Darwin adds: "Now, if we had any reason to suppose that St. Helena had, during a long period, gone on slowly subsiding, every difficulty would be removed...I am much inclined to suspect that we shall hereafter find in all such cases that the land with the adjoining bed of the sea has in truth subsided..." (loc. cit., pages 25-6).) The foundation of his views, viz., of one great sudden upheaval, strikes me as threefold. First, to account for the great dislocations. This strikes me as the odder, as he admits that a little northwards there were many and some violent dislocations at many periods during the accumulation of the Palaeozoic series. If you argue against him, allude to the cool assumption that petty forces are conflicting: look at volcanoes; look at recurrent similar earthquakes at same spots; look at repeatedly injected intrusive masses. In my paper on Volcanic Phenomena in the "Geol. Transactions." (482/4. "On the Connection of certain Volcanic Phenomena, and on the Formation of Mountain-chains and the Effects of Continental Elevations." "Geol. Soc. Proc." Volume II., pages 654-60, 1838; "Trans. Geol. Soc." Volume V., pages 601-32, 1842. [Read March 7th, 1838.]) I have argued (and Lonsdale thought well of the argument, in favour, as he remarked, of your original doctrine) that if Hopkins' views are correct, viz., that mountain chains are subordinate consequences to changes of level in mass, then, as we have evidence of such horizontal movements in mass having been slow, the foundation of mountain chains (differing from volcanoes only in matter being injected instead of ejected) must have been slow. Secondly, Ramsay has been influenced, I think, by his Alpine insects; but he is wrong in thinking that there is any necessary connection of tropics and large insects--videlicet--Galapagos Arch., under the equator. Small insects swarm in all parts of tropics, though accompanied generally with large ones. Thirdly, he appears influenced by the absence of newer deposits on the old area, blinded by the supposed necessity of sediment accumulating somewhere near (as no doubt is true) and being PRESERVED--an example, as I think, of the common error which I wrote to you about. The preservation of sedimentary deposits being, as I do not doubt, the exception when they are accumulated during periods of elevation or of stationary level, and therefore the preservation of newer deposits would not be probable, according to your view that Ramsay's great Palaeozoic masses were denuded, whilst slowly rising. Do pray look at end of Chapter II., at what little I have said on this subject in my S. American volume. (482/5. The second chapter of the "Geological Observations" concludes with a Summary on the Recent Elevations of the West Coast of South America, (page 53).) I do not think you can safely argue that the whole surface was probably denuded at same time to the level of the lateral patches of Magnesian conglomerate. The latter part of the paper strikes me as good, but obvious. I shall send him my S. American volume for it is curious on how many similar points we enter, and I modestly hope it may be a half-oz. weight towards his conversion to better views. If he would but reject his great sudden elevations, how sound and good he would be. I doubt whether this letter will be worth the reading. LETTER 483. TO C. LYELL. Down [September 4th, 1849]. It was very good of you to write me so long a letter, which has interested me much. I should have answered it sooner, but I have not been very well for the few last days. Your letter has also flattered me much in many points. I am very glad you have been thinking over the relation of subsidence and the accumulation of deposits; it has to me removed many great difficulties; please to observe that I have carefully abstained from saying that sediment is not deposited during periods of elevation, but only that it is not accumulated to sufficient thickness to withstand subsequent beach action; on both coasts of S. America the amount of sediment deposited, worn away, and redeposited, oftentimes must have been enormous, but still there have been no wide formations produced: just read my discussion (page 135 of my S. American book (483/1. See Letter 556, note. The discussion referred to ("Geological Observations on South America," 1846) deals with the causes of the absence of recent conchiferous deposits on the coasts of South America.)) again with this in your mind. I never thought of your difficulty (i.e. in relation to this discussion) of where was the land whence the three miles of S. Wales strata were derived! (483/2. In his classical paper "On the Denudation of South Wales and the Adjacent Counties of England" ("Mem. Geol. Survey," Volume I., page 297, 1846), Ramsay estimates the thickness of certain Palaeozoic formations in South Wales, and calculates the cubic contents of the strata in the area they now occupy together with the amount removed by denudation; and he goes on to say that it is evident that the quantity of matter employed to form these strata was many times greater than the entire amount of solid land they now represent above the waves. "To form, therefore, so great a thickness, a mass of matter of nearly equal cubic contents must have been worn by the waves and the outpourings of rivers from neighbouring lands, of which perhaps no original trace now remains" (page 334.)) Do you not think that it may be explained by a form of elevation which I have always suspected to have been very common (and, indeed, had once intended getting all facts together), viz. thus?-- (Figure 1. A line drawing of ocean bottom subsiding beside mountains and continent rising.) The frequency of a DEEP ocean close to a rising continent bordered with mountains, seems to indicate these opposite movements of rising and sinking CLOSE TOGETHER; this would easily explain the S. Wales and Eocene cases. I will only add that I should think there would be a little more sediment produced during subsidence than during elevation, from the resulting outline of coast, after long period of rise. There are many points in my volume which I should like to have discussed with you, but I will not plague you: I should like to hear whether you think there is anything in my conjecture on Craters of Elevation (483/3. In the "Geological Observations on Volcanic Islands," 1844, pages 93-6, Darwin speaks of St. Helena, St. Jago and Mauritius as being bounded by a ring of basaltic mountains which he regards as "Craters of Elevation." While unable to accept the theory of Elie de Beaumont and attribute their formation to a dome-shaped elevation and consequent arching of the strata, he recognises a "very great difficulty in admitting that these basaltic mountains are merely the basal fragments of great volcanoes, of which the summits have been either blown off, or, more probably, swallowed by subsidence." An explanation of the origin and structure of these volcanic islands is suggested which would keep them in the class of "Craters of Elevation," but which assumes a slow elevation, during which the central hollow or platform having been formed "not by the arching of the surface, but simply by that part having been upraised to a less height."); I cannot possibly believe that Saint Jago or Mauritius are the basal fragments of ordinary volcanoes; I would sooner even admit E. de Beaumont's views than that--much as I would sooner in my own mind in all cases follow you. Just look at page 232 in my "S. America" for a trifling point, which, however, I remember to this day relieved my mind of a considerable difficulty. (483/4. This probably refers to a paragraph (page 232) "On the Eruptive Sources of the Porphyritic Claystone and Greenstone Lavas." The opinion is put forward that "the difficulty of tracing the streams of porphyries to their ancient and doubtless numerous eruptive sources, may be partly explained by the very general disturbance which the Cordillera in most parts has suffered"; but, Darwin adds, "a more specific cause may be that 'the original points of eruption tend to become the points of injection'...On this view of there being a tendency in the old points of eruption to become the points of subsequent injection and disturbance, and consequently of denudation, it ceases to be surprising that the streams of lava in the porphyritic claystone conglomerate formation, and in other analogous cases, should most rarely be traceable to their actual sources." The latter part of this letter is published in "Life and Letters," I., pages 377, 378.) I remember being struck with your discussion on the Mississippi beds in relation to Pampas, but I should wish to read them over again; I have, however, re-lent your work to Mrs. Rich, who, like all whom I have met, has been much interested by it. I will stop about my own Geology. But I see I must mention that Scrope did suggest (and I have alluded to him, page 118 (483/5. "Geological Observations," Edition II., 1876. Chapter VI. opens with a discussion "On the Separation of the Constituent Minerals of Lava, according to their Specific Gravities." Mr. Darwin calls attention to the fact that Mr. P. Scrope had speculated on the subject of the separation of the trachytic and basaltic series of lavas (page 113).), but without distinct reference and I fear not sufficiently, though I utterly forgot what he wrote) the separation of basalt and trachyte; but he does not appear to have thought about the crystals, which I believe to be the keystone of the phenomenon. I cannot but think this separation of the molten elements has played a great part in the metamorphic rocks: how else could the basaltic dykes have come in the great granitic districts such as those of Brazil? What a wonderful book for labour is d'Archiac!...(483/6. Possibly this refers to d'Archiac's "Histoire des Progres de la Geologie," 1848.) LETTER 484. TO LADY LYELL. Down, Wednesday night [1849?]. I am going to beg a very very great favour of you: it is to translate one page (and the title) of either Danish or Swedish or some such language. I know not to whom else to apply, and I am quite dreadfully interested about the barnacles therein described. Does Lyell know Loven, or his address and title? for I must write to him. If Lyell knows him I would use his name as introduction; Loven I know by name as a first-rate naturalist. Accidentally I forgot to give you the "Footsteps," which I now return, having ordered a copy for myself. I sincerely hope the "Craters of Denudation" prosper; I pin my faith to this view. (484/1. "On Craters of Denudation, with Observations on the Structure and Growth of Volcanic Cones." "Proc. Geol. Soc." Volume VI., 1850, pages 207-34. In a letter to Bunbury (January 17th, 1850) Lyell wrote:..."Darwin adopts my views as to Mauritius, St. Jago, and so-called elevation craters, which he has examined, and was puzzled with."--"Life of Sir Charles Lyell," Volume II., page 158.) Please tell Sir C. Lyell that outside the crater-like mountains at St. Jago, even throughout a distance of two or three miles, there has been much denudation of the older volcanic rocks contemporaneous with those of the ring of mountains. (484/2. The island of St. Jago, one of the Cape de Verde group, is fully described in the "Volcanic Islands," Chapter 1.) I hope that you will not find the page troublesome, and that you will forgive me asking you. LETTER 485. TO C. LYELL. [November 6th, 1849]. I have been deeply interested in your letter, and so far, at least, worthy of the time it must have cost you to write it. I have not much to say. I look at the whole question as settled. Santorin is splendid! it is conclusive! it is perfect! (485/1. "The Gulf of Santorin, in the Grecian Archipelago, has been for two thousand years a scene of active volcanic operations. The largest of the three outer islands of the groups (to which the general name of Santorin is given) is called Thera (or sometimes Santorin), and forms more than two-thirds of the circuit of the Gulf" ("Principles of Geology," Volume II., Edition X., London, 1868, page 65). Lyell attributed "the moderate slope of the beds in Thera...to their having originally descended the inclined flanks of a large volcanic cone..."; he refuted the theory of "Elevation Craters" by Leopold von Buch, which explained the slope of the rocks in a volcanic mountain by assuming that the inclined beds had been originally horizontal and subsequently tilted by an explosion.) You have read Dufrenoy in a hurry, I think, and added to the difficulty--it is the whole hill or "colline" which is composed of tuff with cross-stratification; the central boss or "monticule" is simply trachyte. Now, I have described one tuff crater at Galapagos (page 108) (485/2. The pages refer to Darwin's "Geological Observations on the Volcanic Islands, etc." 1844.) which has broken through a great solid sheet of basalt: why should not an irregular mass of trachyte have been left in the middle after the explosion and emission of mud which produced the overlying tuff? Or, again, I see no difficulty in a mass of trachyte being exposed by subsequent dislocations and bared or cleaned by rain. At Ascension (page 40), subsequent to the last great aeriform explosion, which has covered the country with fragments, there have been dislocations and a large circular subsidence...Do not quote Banks' case (485/3. This refers to Banks' Cove: see "Volcanic Islands," page 107.) (for there has been some denudation there), but the "elliptic one" (page 105), which is 1,500 yards (three-quarters of a nautical mile) in internal diameter...and is the very one the inclination of whose mud stream on tuff strata I measured (before I had ever heard the name Dufrenoy) and found varying from 25 to 30 deg. Albemarle Island, instead of being a crater of elevation, as Von Buch foolishly guessed, is formed of four great subaerial basaltic volcanoes (page 103), of one of which you might like to know the external diameter of the summit or crater was above three nautical miles. There are no "craters of denudation" at Galapagos. (485/4. See Lyell "On Craters of Denudation, with Observations on the Structure and Growth of Volcanic Cones," "Quart. Journ. Geol. Soc." Volume VI., 1850, page 207.) I hope you will allude to Mauritius. I think this is the instance on the largest scale of any known, though imperfectly known. If I were you I would give up consistency (or, at most, only allude in note to your old edition) and bring out the Craters of Denudation as a new view, which it essentially is. You cannot, I think, give it prominence as a novelty and yet keep to consistency and passages in old editions. I should grudge this new view being smothered in your address, and should like to see a separate paper. The one great channel to Santorin and Palma, etc., etc., is just like the one main channel being kept open in atolls and encircling barrier reefs, and on the same principle of water being driven in through several shallow breaches. I of course utterly reprobate my wild notion of circular elevation; it is a satisfaction to me to think that I perceived there was a screw loose in the old view, and, so far, I think I was of some service to you. Depend on it, you have for ever smashed, crushed, and abolished craters of elevation. There must be craters of engulfment, and of explosion (mere modifications of craters of eruption), but craters of denudation are the ones which have given rise to all the discussions. Pray give my best thanks to Lady Lyell for her translation, which was as clear as daylight to me, including "leglessness." LETTER 486. TO C. LYELL. Down [November 20th, 1849]. I remembered the passage in E. de B. [Elie de Beaumont] and have now re-read it. I have always and do still entirely disbelieve it; in such a wonderful case he ought to have hammered every inch of rock up to actual junction; he describes no details of junction, and if I were in your place I would absolutely dispute the fact of junction (or articulation as he oddly calls it) on such evidence. I go farther than you; I do not believe in the world there is or has been a junction between a dike and stream of lava of exact shape of either (1) or (2) Figure 2]. (Figures 2, 3 and 4.) If dike gave immediate origin to volcanic vent we should have craters of [an] elliptic shape [Figure 3]. I believe that when the molten rock in a dike comes near to the surface, some one two or three points will always certainly chance to afford an easier passage upward to the actual surface than along the whole line, and therefore that the dike will be connected (if the whole were bared and dissected) with the vent by a column or cone (see my elegant drawing) of lava [Figure 4]. I do not doubt that the dikes are thus indirectly connected with eruptive vents. E. de B. seems to have observed many of his T; now without he supposes the whole line of fissure or dike to have poured out lava (which implies, as above remarked, craters of an elliptic or almost linear shape) on both sides, how extraordinarily improbable it is, that there should have been in a single line of section so many intersections of points eruption; he must, I think, make his orifices of eruption almost linear or, if not so, astonishingly numerous. One must refer to what one has seen oneself: do pray, when you go home, look at the section of a minute cone of eruption at the Galapagos, page 109 (486/1. "Geological Observations on Volcanic Islands." London, 1890, page 238.), which is the most perfect natural dissection of a crater which I have ever heard of, and the drawing of which you may, I assure you, trust; here the arching over of the streams as they were poured out over the lip of the crater was evident, and are now thus seen united to the central irregular column. Again, at St. Jago I saw some horizontal sections of the bases of small craters, and the sources or feeders were circular. I really cannot entertain a doubt that E. de B. is grossly wrong, and that you are right in your view; but without most distinct evidence I will never admit that a dike joins on rectangularly to a stream of lava. Your argument about the perpendicularity of the dike strikes me as good. The map of Etna, which I have been just looking at, looks like a sudden falling in, does it not? I am not much surprised at the linear vent in Santorin (this linear tendency ought to be difficult to a circular-crater-of-elevation-believer), I think Abich (486/2. "Geologische Beobachtungen uber die vulkanischen Erscheinungen und Bildungen in Unter- und Mittel-Italien." Braunschweig, 1841.) describes having seen the same actual thing forming within the crater of Vesuvius. In such cases what outline do you give to the upper surface of the lava in the dike connecting them? Surely it would be very irregular and would send up irregular cones or columns as in my above splendid drawing. At the Royal on Friday, after more doubt and misgiving than I almost ever felt, I voted to recommend Forbes for Royal Medal, and that view was carried, Sedgwick taking the lead. I am glad to hear that all your party are pretty well. I know from experience what you must have gone through. From old age with suffering death must be to all a happy release. (486/3. This seems to refer to the death of Sir Charles Lyell's father, which occurred on November 8th, 1849.) I saw Dan Sharpe the other day, and he told me he had been working at the mica schist (i.e. not gneiss) in Scotland, and that he was quite convinced my view was right. You are wrong and a heretic on this point, I know well. LETTER 487. TO C.H.L. WOODD. Down, March 4th [1850]. (487/1. The paper was sent in MS., and seems not to have been published. Mr. Woodd was connected by marriage with Mr. Darwin's cousin, the late Rev. W. Darwin Fox. It was perhaps in consequence of this that Mr. Darwin proposed Mr. Woodd for the Geological Society.) I have read over your paper with attention; but first let me thank you for your very kind expressions towards myself. I really feel hardly competent to discuss the questions raised by your paper; I feel the want of mathematical mechanics. All such problems strike me as awfully complicated; we do not even know what effect great pressure has on retarding liquefaction by heat, nor, I apprehend, on expansion. The chief objection which strikes me is a doubt whether a mass of strata, when heated, and therefore in some slight degree at least softened, would bow outwards like a bar of metal. Consider of how many subordinate layers each great mass would be composed, and the mineralogical changes in any length of any one stratum: I should have thought that the strata would in every case have crumpled up, and we know how commonly in metamorphic strata, which have undergone heat, the subordinate layers are wavy and sinuous, which has always been attributed to their expansion whilst heated. Before rocks are dried and quarried, manifold facts show how extremely flexible they are even when not at all heated. Without the bowing out and subsequent filling in of the roof of the cavity, if I understand you, there would be no subsidence. Of course the crumpling up of the strata would thicken them, and I see with you that this might compress the underlying fluidified rock, which in its turn might escape by a volcano or raise a weaker part of the earth's crust; but I am too ignorant to have any opinion whether force would be easily propagated through a viscid mass like molten rock; or whether such viscid mass would not act in some degree like sand and refuse to transmit pressure, as in the old experiment of trying to burst a piece of paper tied over the end of a tube with a stick, an inch or two of sand being only interposed. I have always myself felt the greatest difficulty in believing in waves of heat coming first to this and then to that quarter of the world: I suspect that heat plays quite a subordinate part in the upward and downward movements of the earth's crust; though of course it must swell the strata where first affected. I can understand Sir J. Herschel's manner of bringing heat to unheated strata--namely, by covering them up by a mile or so of new strata, and then the heat would travel into the lower ones. But who can tell what effect this mile or two of new sedimentary strata would have from mere gravity on the level of the supporting surface? Of course such considerations do not render less true that the expansion of the strata by heat would have some effect on the level of the surface; but they show us how awfully complicated the phenomenon is. All young geologists have a great turn for speculation; I have burned my fingers pretty sharply in that way, and am now perhaps become over-cautious; and feel inclined to cavil at speculation when the direct and immediate effect of a cause in question cannot be shown. How neatly you draw your diagrams; I wish you would turn your attention to real sections of the earth's crust, and then speculate to your heart's content on them; I can have no doubt that speculative men, with a curb on, make far the best observers. I sincerely wish I could have made any remarks of more interest to you, and more directly bearing on your paper; but the subject strikes me as too difficult and complicated. With every good wish that you may go on with your geological studies, speculations, and especially observations... LETTER 488. TO C. LYELL. Down, March 24th [1853]. I have often puzzled over Dana's case, in itself and in relation to the trains of S. American volcanoes of different heights in action at the same time (page 605, Volume V. "Geological Transactions." (488/1. "On the Connection of certain Volcanic Phenomena in South America, and on the Formation of Mountain Chains and Volcanoes, as the Effect of the same Power by which Continents are Elevated" ("Trans. Geol. Soc." Volume V., page 601, 1840). On page 605 Darwin records instances of the simultaneous activity after an earthquake of several volcanoes in the Cordillera.)) I can throw no light on the subject. I presume you remember that Hopkins (488/2. See "Report on the Geological Theories of Elevation and Earthquakes," by W. Hopkins, "Brit. Assoc. Rep." 1847, page 34.) in some one (I forget which) of his papers discusses such cases, and urgently wishes the height of the fluid lava was known in adjoining volcanoes when in contemporaneous action; he argues vehemently against (as far as I remember) volcanoes in action of different heights being connected with one common source of liquefied rock. If lava was as fluid as water, the case would indeed be hopeless; and I fancy we should be led to look at the deep-seated rock as solid though intensely hot, and becoming fluid as soon as a crack lessened the tension of the super-incumbent strata. But don't you think that viscid lava might be very slow in communicating its pressure equally in all directions? I remember thinking strongly that Dana's case within the one crater of Kilauea proved too much; it really seems monstrous to suppose that the lava within the same crater is not connected at no very great depth. When one reflects on (and still better sees) the enormous masses of lava apparently shot miles high up, like cannon-balls, the force seems out of all proportion to the mere gravity of the liquefied lava; I should think that a channel a little straightly or more open would determine the line of explosion, like the mouth of a cannon compared to the touch-hole. If a high-pressure boiler was cracked across, no one would think for a moment that the quantity of water and steam expelled at different points depended on the less or greater height of the water within the boiler above these points, but on the size of the crack at these points; and steam and water might be driven out both at top and bottom. May not a volcano be likened to a protruding and cracked portion on a vast natural high-pressure boiler, formed by the surrounding area of country? In fact, I think my simile would be truer if the difference consisted only in the cracked case of the boiler being much thicker in some parts than in others, and therefore having to expel a greater thickness or depth of water in the thicker cracks or parts--a difference of course absolutely as nothing. I have seen an old boiler in action, with steam and drops of water spurting out of some of the rivet-holes. No one would think whether the rivet-holes passed through a greater or less thickness of iron, or were connected with the water higher or lower within the boiler, so small would the gravity be compared with the force of the steam. If the boiler had been not heated, then of course there would be a great difference whether the rivet-holes entered the water high or low, so that there was greater or less pressure of gravity. How to close my volcanic rivet-holes I don't know. I do not know whether you will understand what I am driving at, and it will not signify much whether you do or not. I remember in old days (I may mention the subject as we are on it) often wishing I could get you to look at continental elevations as THE phenomenon, and volcanic outbursts and tilting up of mountain chains as connected, but quite secondary, phenomena. I became deeply impressed with the truth of this view in S. America, and I do not think you hold it, or if so make it clear: the same explanation, whatever it may be, which will account for the whole coast of Chili rising, will and must apply to the volcanic action of the Cordillera, though modified no doubt by the liquefied rock coming to the surface and reaching water, and so [being] rendered explosive. To me it appears that this ought to be borne in mind in your present subject of discussion. I have written at too great length; and have amused myself if I have done you no good--so farewell. LETTER 489. TO C. LYELL. Down, July 5th [1856]. I am very much obliged for your long letter, which has interested me much; but before coming to the volcanic cosmogony I must say that I cannot gather your verdict as judge and jury (and not as advocate) on the continental extensions of late authors (489/1. See "Life and Letters," II., page 74; Letter to Lyell, June 25th, 1856: also letters in the sections of the present work devoted to Evolution and Geographical Distribution.), which I must grapple with, and which as yet strikes me as quite unphilosophical, inasmuch as such extensions must be applied to every oceanic island, if to any one, as to Madeira; and this I cannot admit, seeing that the skeletons, at least, of our continents are ancient, and seeing the geological nature of the oceanic islands themselves. Do aid me with your judgment: if I could honestly admit these great [extensions], they would do me good service. With respect to active volcanic areas being rising areas, which looks so pretty on the coral maps, I have formerly felt "uncomfortable" on exactly the same grounds with you, viz. maritime position of volcanoes; and still more from the immense thicknesses of Silurian, etc., volcanic strata, which thicknesses at first impress the mind with the idea of subsidence. If this could be proved, the theory would be smashed; but in deep oceans, though the bottom were rising, great thicknesses of submarine lava might accumulate. But I found, after writing Coral Book, cases in my notes of submarine vesicular lava-streams in the upper masses of the Cordillera, formed, as I believe, during subsidence, which staggered me greatly. With respect to the maritime position of volcanoes, I have long been coming to the conclusion that there must be some law causing areas of elevation (consequently of land) and of subsidence to be parallel (as if balancing each other) and closely approximate; I think this from the form of continents with a deep ocean on one side, from coral map, and especially from conversations with you on immense subsidences of the Carboniferous and [other] periods, and yet with continued great supply of sediment. If this be so, such areas, with opposite movements, would probably be separated by sets of parallel cracks, and would be the seat of volcanoes and tilts, and consequently volcanoes and mountains would be apt to be maritime; but why volcanoes should cling to the rising edge of the cracks I cannot conjecture. That areas with extinct volcanic archipelagoes may subside to any extent I do not doubt. Your view of the bottom of Atlantic long sinking with continued volcanic outbursts and local elevations at Madeira, Canaries, etc., grates (but of course I do not know how complex the phenomena are which are thus explained) against my judgment; my general ideas strongly lead me to believe in elevatory movements being widely extended. One ought, I think, never to forget that when a volcano is in action we have distinct proof of an action from within outwards. Nor should we forget, as I believe follows from Hopkins (489/2. "Researches in Physical Geology," W. Hopkins, "Trans. Phil. Soc. Cambridge," Volume VI., 1838. See also "Report on the Geological Theories of Elevation and Earthquakes," W. Hopkins, "Brit. Assoc. Rep." page 33, 1847 (Oxford meeting).), and as I have insisted in my Earthquake paper, that volcanoes and mountain chains are mere accidents resulting from the elevation of an area, and as mountain chains are generally long, so should I view areas of elevation as generally large. (489/3. "On the Connexion of certain Volcanic Phenomena in S. America, and on the Formation of Mountain Chains and Volcanoes, as the Effect of the same Power by which Continents are Elevated," "Trans. Geol. Soc." Volume V., page 601, 1840. "Bearing in mind Mr. Hopkins' demonstration, if there be considerable elevation there must be fissures, and, if fissures, almost certainly unequal upheaval, or subsequent sinking down, the argument may be finally thus put: mountain chains are the effects of continental elevations; continental elevations and the eruptive force of volcanoes are due to one great motive, now in progressive action..." (loc. cit., page 629).) Your old original view that great oceans must be sinking areas, from there being causes making land and yet there being little land, has always struck me till lately as very good. But in some degree this starts from the assumption that within periods of which we know anything there was either a continent in such areas, or at least a sea-bottom of not extreme depth. LETTER 490. TO C. LYELL. King's Head Hotel, Sandown, Isle of Wight, July 18th [1858]. I write merely to thank you for the abstract of the Etna paper. (490/1. "On the Structure of Lavas which have Consolidated on Steep Slopes, with Remarks on the Mode of Origin of Mount Etna and on the Theory of 'Craters of Elevation,'" by C. Lyell, "Phil. Trans. R. Soc." Volume CXLVIII., page 703, 1859.) It seems to me a very grand contribution to our volcanic knowledge. Certainly I never expected to see E. de B.'s [Elie de Beaumont] theory of slopes so completely upset. He must have picked out favourable cases for measurement. And such an array of facts he gives! You have scotched, and will see die, I now think, the Crater of Elevation theory. But what vitality there is in a plausible theory! (490/2. The rest of this letter is published in "Life and Letters," II., page 129.) LETTER 491. TO C. LYELL. Down, November 25th [1860]. I have endeavoured to think over your discussion, but not with much success. You will have to lay down, I think, very clearly, what foundation you argue from--four parts (which seems to me exceedingly moderate on your part) of Europe being now at rest, with one part undergoing movement. How it is, that from this you can argue that the one part which is now moving will have rested since the commencement of the Glacial period in the proportion of four to one, I do not pretend to see with any clearness; but does not your argument rest on the assumption that within a given period, say two or three million years, the whole of Europe necessarily has to undergo movement? This may be probable or not so, but it seems to me that you must explain the foundation of your argument from space to time, which at first, to me was very far from obvious. I can, of course, see that if you can make out your argument satisfactorily to yourself and others it would be most valuable. I can imagine some one saying that it is not fair to argue that the great plains of Europe and the mountainous districts of Scotland and Wales have been at all subjected to the same laws of movement. Looking to the whole world, it has been my opinion, from the very size of the continents and oceans, and especially from the enormous ranges of so many mountain-chains (resulting from cracks which follow from vast areas of elevation, as Hopkins argues (491/1. See "Report on the Geological Theories of Elevation and Earthquakes." by William Hopkins. "Brit. Assoc. Rep." 1847, pages 33-92; also the Anniversary Address to the Geological Society by W. Hopkins in 1852 ("Quart. Journ. Geol. Soc." Volume VIII.); in this Address, pages lxviii et seq.) reference is made to the theory of elevation which rests on the supposition "of the simultaneous action of an upheaving force at every point of the area over which the phenomena of elevation preserve a certain character of continuity...The elevated mass...becomes stretched, and is ultimately torn and fissured in those directions in which the tendency thus to tear is greatest...It is thus that the complex phenomena of elevation become referable to a general and simple mechanical cause...")) and from other reasons, it has been my opinion that, as a general rule, very large portions of the world have been simultaneously affected by elevation or subsidence. I can see that this does not apply so strongly to broken Europe, any more than to the Malay Archipelago. Yet, had I been asked, I should have said that probably nearly the whole of Europe was subjected during the Glacial period to periods of elevation and of subsidence. It does not seem to me so certain that the kinds of partial movement which we now see going on show us the kind of movement which Europe has been subjected to since the commencement of the Glacial period. These notions are at least possible, and would they not vitiate your argument? Do you not rest on the belief that, as Scandinavia and some few other parts are now rising, and a few others sinking, and the remainder at rest, so it has been since the commencement of the Glacial period? With my notions I should require this to be made pretty probable before I could put much confidence in your calculations. You have probably thought this all over, but I give you the reflections which come across me, supposing for the moment that you took the proportions of space at rest and in movement as plainly applicable to time. I have no doubt that you have sufficient evidence that, at the commencement of the Glacial period, the land in Scotland, Wales, etc., stood as high or higher than at present, but I forget the proofs. Having burnt my own fingers so consumedly with the Wealden, I am fearful for you, but I well know how infinitely more cautious, prudent, and far-seeing you are than I am; but for heaven's sake take care of your fingers; to burn them severely, as I have done, is very unpleasant. Your 2 1/2 feet for a century of elevation seems a very handsome allowance. can D. Forbes really show the great elevation of Chili? I am astounded at it, and I took some pains on the point. I do not pretend to say that you may not be right to judge of the past movements of Europe by those now and recently going on, yet it somehow grates against my judgment,--perhaps only against my prejudices. As a change from elevation to subsidence implies some great subterranean or cosmical change, one may surely calculate on long intervals of rest between. Though, if the cause of the change be ever proved to be astronomical, even this might be doubtful. P.S.--I do not know whether I have made clear what I think probable, or at least possible: viz., that the greater part of Europe has at times been elevated in some degree equably; at other times it has all subsided equably; and at other times might all have been stationary; and at other times it has been subjected to various unequal movements, up and down, as at present. LETTER 492. TO C. LYELL. Down, December 4th [1860]. It certainly seems to me safer to rely solely on the slowness of ascertained up-and-down movement. But you could argue length of probable time before the movement became reversed, as in your letter. And might you not add that over the whole world it would probably be admitted that a larger area is NOW at rest than in movement? and this I think would be a tolerably good reason for supposing long intervals of rest. You might even adduce Europe, only guarding yourself by saying that possibly (I will not say probably, though my prejudices would lead me to say so) Europe may at times have gone up and down all together. I forget whether in a former letter you made a strong point of upward movement being always interrupted by long periods of rest. After writing to you, out of curiosity I glanced at the early chapters in my "Geology of South America," and the areas of elevation on the E. and W. coasts are so vast, and proofs of many successive periods of rest so striking, that the evidence becomes to my mind striking. With regard to the astronomical causes of change: in ancient days in the "Beagle" when I reflected on the repeated great oscillations of level on the very same area, and when I looked at the symmetry of mountain chains over such vast spaces, I used to conclude that the day would come when the slow change of form in the semi-fluid matter beneath the crust would be found to be the cause of volcanic action, and of all changes of level. And the late discussion in the "Athenaeum" (492/1. "On the Change of Climate in Different Regions of the Earth." Letters from Sir Henry James, Col. R.E., "Athenaeum," August 25th, 1860, page 256; September 15th, page 355; September 29th, page 415; October 13th, page 483. Also letter from J. Beete Jukes, Local Director of the Geological Survey of Ireland, loc. cit., September 8th, page 322; October 6th, page 451.), by Sir H. James (though his letter seemed to me mighty poor, and what Jukes wrote good), reminded me of this notion. In case astronomical agencies should ever be proved or rendered probable, I imagine, as in nutation or precession, that an upward movement or protrusion of fluidified matter below might be immediately followed by movement of an opposite nature. This is all that I meant. I have not read Jamieson, or yet got the number. (492/2. Possibly William Jameson, "Journey from Quito to Cayambe," "Geog. Soc. Journ." Volume XXXI., page 184, 1861.) I was very much struck with Forbes' explanation of n[itrate] of soda beds and the saliferous crust, which I saw and examined at Iquique. (492/3. "On the Geology of Bolivia and Southern Peru," by D. Forbes, "Quart. Journ. Geol. Soc." Volume XVII., page 7, 1861. Mr. Forbes attributes the formation of the saline deposits to lagoons of salt water, the communication of which with the sea has been cut off by the rising of the land (loc. cit., page 13).) I often speculated on the greater rise inland of the Cordilleras, and could never satisfy myself... I have not read Stur, and am awfully behindhand in many things...(492/4. The end of this letter is published as a footnote in "Life and Letters," II., page 352.) (FIGURE 5. Map of part of South America and the Galapagos Archipelago.) LETTER 493. TO C. LYELL. Down, July 18th [1867]. (493/1. The first part of this letter is published in "Life and Letters," III., page 71.) (493/2. Tahiti (Society Islands) is coloured blue in the map showing the distribution of the different kinds of reefs in "The Structure and Distribution of Coral Reefs," Edition III., 1889, page 185. The blue colour indicates the existence of barrier reefs and atolls which, on Darwin's theory, point to subsidence.) Tahiti is, I believe, rightly coloured, for the reefs are so far from the land, and the ocean so deep, that there must have been subsidence, though not very recently. I looked carefully, and there is no evidence of recent elevation. I quite agree with you versus Herschel on Volcanic Islands. (493/3. Sir John Herschel suggested that the accumulation on the sea-floor of sediment, derived from the waste of the island, presses down the bed of the ocean, the continent being on the other hand relieved of pressure; "this brings about a state of strain in the crust which will crack in its weakest spot, the heavy side going down, and the light side rising." In discussing this view Lyell writes ("Principles," Volume II. Edition X., page 229), "This hypothesis appears to me of very partial application, for active volcanoes, even such as are on the borders of continents, are rarely situated where great deltas have been forming, whether in Pliocene or post-Tertiary times. The number, also, of active volcanoes in oceanic islands is very great, not only in the Pacific, but equally in the Atlantic, where no load of coral matter...can cause a partial weighting and pressing down of a supposed flexible crust.") Would not the Atlantic and Antarctic volcanoes be the best examples for you, as there then can be no coral mud to depress the bottom? In my "Volcanic Islands," page 126, I just suggest that volcanoes may occur so frequently in the oceanic areas as the surface would be most likely to crack when first being elevated. I find one remark, page 128 (493/4. "Volcanic Islands," page 128: "The islands, moreover, of some of the small volcanic groups, which thus border continents, are placed in lines related to those along which the adjoining shores of the continents trend" [see Figure 5].), which seems to me worth consideration--viz. the parallelism of the lines of eruption in volcanic archipelagoes with the coast lines of the nearest continent, for this seems to indicate a mechanical rather than a chemical connection in both cases, i.e. the lines of disturbance and cracking. In my "South American Geology," page 185 (493/5. "Geological Observations on South America," London, 1846, page 185.), I allude to the remarkable absence at present of active volcanoes on the east side of the Cordillera in relation to the absence of the sea on this side. Yet I must own I have long felt a little sceptical on the proximity of water being the exciting cause. The one volcano in the interior of Asia is said, I think, to be near great lakes; but if lakes are so important, why are there not many other volcanoes within other continents? I have always felt rather inclined to look at the position of volcanoes on the borders of continents, as resulting from coast lines being the lines of separation between areas of elevation and subsidence. But it is useless in me troubling you with my old speculations. LETTER 494. TO A.R. WALLACE. March 22nd [1869]. (494/1. The following extract from a letter to Mr. Wallace refers to his "Malay Archipelago," 1869.) I have only one criticism of a general nature, and I am not sure that other geologists would agree with me. You repeatedly speak as if the pouring out of lava, etc., from volcanoes actually caused the subsidence of an adjoining area. I quite agree that areas undergoing opposite movements are somehow connected; but volcanic outbursts must, I think, be looked at as mere accidents in the swelling up of a great dome or surface of plutonic rocks, and there seems no more reason to conclude that such swelling or elevation in mass is the cause of the subsidence, than that the subsidence is the cause of the elevation, which latter view is indeed held by some geologists. I have regretted to find so little about the habits of the many animals which you have seen. LETTER 495. TO C. LYELL. Down, May 20th, 1869. I have been much pleased to hear that you have been looking at my S. American book (495/1. "Geological Observations on South America," London, 1846.), which I thought was as completely dead and gone as any pre-Cambrian fossil. You are right in supposing that my memory about American geology has grown very hazy. I remember, however, a paper on the Cordillera by D. Forbes (495/2. "Geology of Bolivia and South Peru," by Forbes, "Quart. Journ. Geol. Soc." Volume XVII., pages 7-62, 1861. Forbes admits that there is "the fullest evidence of elevation of the Chile coast since the arrival of the Spaniards. North of Arica, if we accept the evidence of M. d'Orbigny and others, the proof of elevation is much more decided; and consequently it may be possible that here, as is the case about Lima, according to Darwin, the elevation may have taken place irregularly in places..." (loc. cit., page 11).), with splendid sections, which I saw in MS., but whether "referred" to me or lent to me I cannot remember. This would be well worth your looking to, as I think he both supports and criticises my views. In Ormerod's Index to the Journal (495/3. "Classified Index to the Transactions, Proceedings and Quarterly Journal of the Geological Society."), which I do not possess, you would, no doubt, find a reference; but I think the sections would be worth borrowing from Forbes. Domeyko (495/4. Reference is made by Forbes in his paper on Bolivia and Peru to the work of Ignacio Domeyko on the geology of Chili. Several papers by this author were published in the "Annales des Mines" between 1840 and 1869, also in the "Comptes Rendus" of 1861, 1864, etc.) has published in the "Comptes Rendus" papers on Chili, but not, as far as I can remember, on the structure of the mountains. Forbes, however, would know. What you say about the plications being steepest in the central and generally highest part of the range is conclusive to my mind that there has been the chief axis of disturbance. The lateral thrusting has always appeared to me fearfully perplexing. I remember formerly thinking that all lateral flexures probably occurred deep beneath the surface, and have been brought into view by an enormous superincumbent mass having been denuded. If a large and deep box were filled with layers of damp paper or clay, and a blunt wedge was slowly driven up from beneath, would not the layers above it and on both sides become greatly convoluted, whilst those towards the top would be only slightly arched? When I spoke of the Andes being comparatively recent, I suppose that I referred to the absence of the older formations. In looking to my volume, which I have not done for many years, I came upon a passage (page 232) which would be worth your looking at, if you have ever felt perplexed, as I often was, about the sources of volcanic rocks in mountain chains. You have stirred up old memories, and at the risk of being a bore I should like to call your attention to another point which formerly perplexed me much--viz. the presence of basaltic dikes in most great granitic areas. I cannot but think the explanation given at page 123 of my "Volcanic Islands" is the true one. (495/5. On page 123 of the "Geological Observations on the Volcanic Islands visited during the Voyage of H.M.S. 'Beagle,'" 1844, Darwin quotes several instances of greenstone and basaltic dikes intersecting granitic and allied metamorphic rocks. He suggests that these dikes "have been formed by fissures penetrating into partially cooled rocks of the granitic and metamorphic series, and by their more fluid parts, consisting chiefly of hornblende oozing out, and being sucked into such fissures.") LETTER 496. TO VICTOR CARUS. Down, March 21st, 1876. The very kind expressions in your letter have gratified me deeply. I quite forget what I said about my geological works, but the papers referred to in your letter are the right ones. I enclose a list with those which are certainly not worth translating marked with a red line; but whether those which are not thus marked with a red line are worth translation you will have to decide. I think much more highly of my book on "Volcanic Islands" since Mr. Judd, by far the best judge on the subject in England, has, as I hear, learnt much from it. I think the short paper on the "formation of mould" is worth translating, though, if I have time and strength, I hope to write another and longer paper on the subject. I can assure you that the idea of any one translating my books better than you never even momentarily crossed my mind. I am glad that you can give a fairly good account of your health, or at least that it is not worse. LETTER 497. TO T. MELLARD READE. London, December 9th, 1880. I am sorry to say that I do not return home till the middle of next week, and as I order no pamphlets to be forwarded to me by post, I cannot return the "Geolog. Mag." until my return home, nor could my servants pick it out of the multitude which come by the post. (497/1. Article on "Oceanic Islands," by T. Mellard Reade, "Geol. Mag." Volume VIII., page 75, 1881.) As I remarked in a letter to a friend, with whom I was discussing Wallace's last book (497/2. Wallace's "Island Life," 1880.), the subject to which you refer seems to me a most perplexing one. The fact which I pointed out many years ago, that all oceanic islands are volcanic (except St. Paul's, and now this is viewed by some as the nucleus of an ancient volcano), seems to me a strong argument that no continent ever occupied the great oceans. (497/3. "During my investigations on coral reefs I had occasion to consult the works of many voyagers, and I was invariably struck with the fact that, with rare exceptions, the innumerable islands scattered through the Pacific, Indian, and Atlantic Oceans were composed either of volcanic or of modern coral rocks" ("Geological Observations on Volcanic Islands, etc." Edition II., 1876, page 140).) Then there comes the statement from the "Challenger" that all sediment is deposited within one or two hundred miles from the shores, though I should have thought this rather doubtful with respect to great rivers like the Amazons. The chalk formerly seemed to me the best case of an ocean having extended where a continent now stands; but it seems that some good judges deny that the chalk is an oceanic deposit. On the whole, I lean to the side that the continents have since Cambrian times occupied approximately their present positions. But, as I have said, the question seems a difficult one, and the more it is discussed the better. LETTER 498. TO A. AGASSIZ. Down, January 1st, 1881. I must write a line or two to thank you much for having written to me so long a letter on coral reefs at a time when you must have been so busy. Is it not difficult to avoid believing that the wonderful elevation in the West Indies must have been accompanied by much subsidence, notwithstanding the state of Florida? (498/1. The Florida reefs cannot be explained by subsidence. Alexander Agassiz, who has described these reefs in detail ("Three Cruises of the U.S. Coast and Geodetic Survey Steamer 'Blake,'" 2 volumes, London, 1888), shows that the southern extremity of the peninsula "is of comparatively recent growth, consisting of concentric barrier-reefs, which have been gradually converted into land by the accumulation of intervening mud-flats" (see also Appendix II., page 287, to Darwin's "Coral Reefs," by T.G. Bonney, Edition III., 1889.)) When reflecting in old days on the configuration of our continents, the position of mountain chains, and especially on the long-continued supply of sediment over the same areas, I used to think (as probably have many other persons) that areas of elevation and subsidence must as a general rule be separated by a single great line of fissure, or rather of several closely adjoining lines of fissure. I mention this because, when looking within more recent times at charts with the depths of the sea marked by different tints, there seems to be some connection between the profound depths of the ocean and the trends of the nearest, though distant, continents; and I have often wished that some one like yourself, to whom the subject was familiar, would speculate on it. P.S.--I do hope that you will re-urge your views about the reappearance of old characters (498/2. See "Life and Letters," III., pages 245, 246.), for, as far as I can judge, the most important views are often neglected unless they are urged and re-urged. I am greatly indebted to you for sending me very many most valuable works published at your institution. 2.IX.II. ICE-ACTION, 1841-1882. LETTER 499. TO C. LYELL. [1841.] Your extract has set me puzzling very much, and as I find I am better at present for not going out, you must let me unload my mind on paper. I thought everything so beautifully clear about glaciers, but now your case and Agassiz's statement about the cavities in the rock formed by cascades in the glaciers, shows me I don't understand their structure at all. I wish out of pure curiosity I could make it out. (499/1. "Etudes sur les Glaciers," by Louis Agassiz, 1840, contains a description of cascades (page 343), and "des cavites interieures" (page 348).) If the glacier travelled on (and it certainly does travel on), and the water kept cutting back over the edge of the ice, there would be a great slit in front of the cascade; if the water did not cut back, the whole hollow and cascade, as you say, must travel on; and do you suppose the next season it falls down some crevice higher up? In any case, how in the name of Heaven can it make a hollow in solid rock, which surely must be a work of many years? I must point out another fact which Agassiz does not, as it appears to me, leave very clear. He says all the blocks on the surface of the glaciers are angular, and those in the moraines rounded, yet he says the medial moraines whence the surface rocks come and are a part [of], are only two lateral moraines united. Can he refer to terminal moraines alone when he says fragments in moraines are rounded? What a capital book Agassiz's is. In [reading] all the early part I gave up entirely the Jura blocks, and was heartily ashamed of my appendix (499/2. "M. Agassiz has lately written on the subject of the glaciers and boulders of the Alps. He clearly proves, as it appears to me, that the presence of the boulders on the Jura cannot be explained by any debacle, or by the power of ancient glaciers driving before them moraines...M. Agassiz also denies that they were transported by floating ice." ("Voyages of the 'Adventure' and 'Beagle,'" Volume III., 1839: "Journal and Remarks: Addenda," page 617.)) (and am so still of the manner in which I presumptuously speak of Agassiz), but it seems by his own confession that ordinary glaciers could not have transported the blocks there, and if an hypothesis is to be introduced the sea is much simpler; floating ice seems to me to account for everything as well as, and sometimes better than the solid glaciers. The hollows, however, formed by the ice-cascades appear to me the strongest hostile fact, though certainly, as you said, one sees hollow round cavities on present rock-beaches. I am glad to observe that Agassiz does not pretend that direction of scratches is hostile to floating ice. By the way, how do you and Buckland account for the "tails" of diluvium in Scotland? (499/3. Mr. Darwin speaks of the tails of diluvium in Scotland extending from the protected side of a hill, of which the opposite side, facing the direction from which the ice came, is marked by grooves and striae (loc. cit., pages 622, 623).) I thought in my appendix this made out the strongest argument for rocks having been scratched by floating ice. Some facts about boulders in Chiloe will, I think, in a very small degree elucidate some parts of Jura case. What a grand new feature all this ice work is in Geology! How old Hutton would have stared! (499/4. Sir Charles Lyell speaks of the Huttonian theory as being characterised by "the exclusion of all causes not supposed to belong to the present order of Nature" (Lyell's "Principles," Edition XII., volume I., page 76, 1875). Sir Archibald Geikie has recently edited the third volume of Hutton's "Theory of the Earth," printed by the Geological Society, 1899. See also "The Founders of Geology," by Sir Archibald Geikie; London, 1897.) I ought to be ashamed of myself for scribbling on so. Talking of shame, I have sent a copy of my "Journal" (499/5. "Journal and Remarks," 1832-36. See note 2, page 148.) with very humble note to Agassiz, as an apology for the tone I used, though I say, I daresay he has never seen my appendix, or would care at all about it. I did not suppose my note about Glen Roy could have been of any use to you--I merely scribbled what came uppermost. I made one great oversight, as you would perceive. I forgot the Glacier theory: if a glacier most gradually disappeared from mouth of Spean Valley [this] would account for buttresses of shingle below lowest shelf. The difficulty I put about the ice-barrier of the middle Glen Roy shelf keeping so long at exactly same level does certainly appear to me insuperable. (499/5. For a description of the shelves or parallel roads in Glen Roy see Darwin's "Observations on the Parallel Roads of Glen Roy, etc." "Phil. Trans. R. Soc." 1839, page 39; also Letter 517 et seq.) What a wonderful fact this breakdown of old Niagara is. How it disturbs the calculations about lengths of time before the river would have reached the lakes. I hope Mrs. Lyell will read this to you, then I shall trust for forgiveness for having scribbled so much. I should have sent back Agassiz sooner, but my servant has been very unwell. Emma is going on pretty well. My paper on South American boulders and "till," which latter deposit is perfectly characterised in Tierra del Fuego, is progressing rapidly. (499/6. "On the Distribution of the Erratic Boulders and on the Contemporaneous Unstratified Deposits of South America," "Trans. Geol. Soc." Volume VI., page 415, 1842.) I much like the term post-Pliocene, and will use it in my present paper several times. P.S.--I should have thought that the most obvious objection to the marine-beach theory for Glen Roy would be the limited extension of the shelves. Though certainly this is not a valid one, after an intermediate one, only half a mile in length, and nowhere else appearing, even in the valley of Glen Roy itself, has been shown to exist. LETTER 500. TO C. LYELL. 1842. I had some talk with Murchison, who has been on a flying visit into Wales, and he can see no traces of glaciers, but only of the trickling of water and of the roots of the heath. It is enough to make an extraneous man think Geology from beginning to end a work of imagination, and not founded on observation. Lonsdale, I observe, pays Buckland and myself the compliment of thinking Murchison not seeing as worth nothing; but I confess I am astonished, so glaringly clear after two or three days did the evidence appear to me. Have you seen last "New Edin. Phil. Journ.", it is ice and glaciers almost from beginning to end. (500/1. "The Edinburgh New Philosophical Journal," Volume XXXIII. (April-October), 1842, contains papers by Sir G.S. Mackenzie, Prof. H.G. Brown, Jean de Charpentier, Roderick Murchison, Louis Agassiz, all dealing with glaciers or ice; also letters to the Editor relating to Prof. Forbes' account of his recent observations on Glaciers, and a paper by Charles Darwin entitled "Notes on the Effects produced by the Ancient Glaciers of Carnarvonshire, and on the Boulders transported by Floating Ice.") Agassiz says he saw (and has laid down) the two lowest terraces of Glen Roy in the valley of the Spean, opposite mouth of Glen Roy itself, where no one else has seen them. (500/2. "The Glacial Theory and its Recent Progress," by Louis Agassiz, loc. cit., page 216. Agassiz describes the parallel terraces on the flanks of Glen Roy and Glen Spean (page 236), and expresses himself convinced "that the Glacial theory alone satisfies all the exigencies of the phenomenon" of the parallel roads.) I carefully examined that spot, owing to the sheep tracks [being] nearly but not quite parallel to the terrace. So much, again, for difference of observation. I do not pretend to say who is right. LETTER 501. TO J.D. HOOKER. Down, October 12th, 1849. I was heartily glad to get your last letter; but on my life your thanks for my very few and very dull letters quite scalded me. I have been very indolent and selfish in not having oftener written to you and kept my ears open for news which would have interested you; but I have not forgotten you. Two days after receiving your letter, there was a short leading notice about you in the "Gardeners' Chronicle" (501/1. The "Gardeners' Chronicle," 1849, page 628.); in which it is said you have discovered a noble crimson rose and thirty rhododendrons. I must heartily congratulate you on these discoveries, which will interest the public; and I have no doubt that you will have made plenty of most interesting botanical observations. This last letter shall be put with all your others, which are now safe together. I am very glad that you have got minute details about the terraces in the valleys: your description sounds curiously like the terraces in the Cordillera of Chili; these latter, however, are single in each valley; but you will hereafter see a description of these terraces in my "Geology of S. America." (501/2. "Geological Observations," pages 10 et passim.) At the end of your letter you speak about giving up Geology, but you must not think of it; I am sure your observations will be very interesting. Your account of the great dam in the Yangma valley is most curious, and quite full; I find that I did not at all understand its wonderful structure in your former letter. Your notion of glaciers pushing detritus into deep fiords (and ice floating fragments on their channels), is in many respects new to me; but I cannot help believing your dam is a lateral moraine: I can hardly persuade myself that the remains of floating ice action, at a period so immensely remote as when the Himalaya stood at a low level in the sea, would now be distinguishable. (501/3. Hooker's "Himalayan Journals," Volume II., page 121, 1854. In describing certain deposits in the Lachoong valley, Hooker writes: "Glaciers might have forced immense beds of gravel into positions that would dam up lakes between the ice and the flanks of the valley" (page 121). In a footnote he adds: "We are still very ignorant of many details of ice action, and especially of the origin of many enormous deposits which are not true moraines." Such deposits are referred to as occurring in the Yangma valley.) Your not having found scored boulders and solid rocks is an objection both to glaciers and floating ice; for it is certain that both produce such. I believe no rocks escape scoring, polishing and mammillation in the Alps, though some lose it easily when exposed. Are you familiar with appearance of ice-action? If I understand rightly, you object to the great dam having been produced by a glacier, owing to the dryness of the lateral valley and general infrequency of glaciers in Himalaya; but pray observe that we may fairly (from what we see in Europe) assume that the climate was formerly colder in India, and when the land stood at a lower height more snow might have fallen. Oddly enough, I am now inclined to believe that I saw a gigantic moraine crossing a valley, and formerly causing a lake above it in one of the great valleys (Valle del Yeso) of the Cordillera: it is a mountain of detritus, which has puzzled me. If you have any further opportunities, do look for scores on steep faces of rock; and here and there remove turf or matted parts to have a look. Again I beg, do not give up Geology:--I wish you had Agassiz's work and plates on Glaciers. (501/4. "Etudes sur les Glaciers." L. Agassiz, Neuchatel, 1840.) I am extremely sorry that the Rajah, ill luck to him, has prevented your crossing to Thibet; but you seem to have seen most interesting country: one is astonished to hear of Fuegian climate in India. I heard from the Sabines that you were thinking of giving up Borneo; I hope that this report may prove true. LETTER 502. TO C. LYELL. Down, May 8th [1855]. The notion you refer to was published in the "Geological Journal" (502/1. "on the Transportal of Erratic Boulders from a lower to a higher Level." By C. Darwin.), Volume IV. (1848), page 315, with reference to all the cases which I could collect of boulders apparently higher than the parent rock. The argument of probable proportion of rock dropped by sea ice compared to land glaciers is new to me. I have often thought of the idea of the viscosity and enormous momentum of great icebergs, and still think that the notion I pointed out in appendix to Ramsay's paper is probable, and can hardly help being applicable in some cases. (502/2. The paper by Ramsay has no appendix; probably, therefore Mr. Darwin's notes were published separately as a paper in the "Phil. Mag.") I wonder whether the "Phil. Journal [Magazine?.]" would publish it, if I could get it from Ramsay or the Geological Society. (502/3. "On the Power of Icebergs to make rectilinear, uniformly-directed grooves across a Submarine Undulatory Surface." By C. Darwin, "Phil. Mag." Volume X., page 96, 1855.) If you chance to meet Ramsay will you ask him whether he has it? I think it would perhaps be worth while just to call the N. American geologists' attention to the idea; but it is not worth any trouble. I am tremendously busy with all sorts of experiments. By the way, Hopkins at the Geological Society seemed to admit some truth in the idea of scoring by (viscid) icebergs. If the Geological Society takes so much [time] to judge of truth of notions, as you were telling me in regard to Ramsay's Permian glaciers (502/4. "On the Occurrence of angular, sub-angular, polished, and striated Fragments and Boulders in the Permian Breccia of Shropshire, Worcestershire, etc.; and on the Probable Existence of Glaciers and Icebergs in the Permian Epoch." By A.C. Ramsay, "Quart. Journ. Geol. Soc." Volume XI., page 185, 1855.), it will be as injurious to progress as the French Institut. LETTER 503. TO J.D. HOOKER. Cliff Cottage, Bournemouth, [September] 21st [1862]. I am especially obliged to you for sending me Haast's communications. (503/1. "Quart. Journ. Geol. Soc." Volume XXI., pages 130, 133, 1865; Volume XXIII., page 342, 1867.) They are very interesting and grand about glacial and drift or marine glacial. I see he alludes to the whole southern hemisphere. I wonder whether he has read the "Origin." Considering your facts on the Alpine plants of New Zealand and remarks, I am particularly glad to hear of the geological evidence of glacial action. I presume he is sure to collect and send over the mountain rat of which he speaks. I long to know what it is. A frog and rat together would, to my mind, prove former connection of New Zealand to some continent; for I can hardly suppose that the Polynesians introduced the rat as game, though so esteemed in the Friendly Islands. Ramsay sent me his paper (503/2. "On the Glacial Origin of certain Lakes in Switzerland, etc." "Quart. Journ. Geol. Soc." Volume XVIII., page 185, 1862.) and asked my opinion on it. I agree with you and think highly of it. I cannot doubt that it is to a large extent true; my only doubt is, that in a much disturbed country, I should have thought that some depressions, and consequently lakes, would almost certainly have been left. I suggested a careful consideration of mountainous tropical countries such as Brazil, peninsula of India, etc.; if lakes are there, [they are] very rare. I should fully subscribe to Ramsay's views. What presumption, as it seems to me, in the Council of Geological Society that it hesitated to publish the paper. We return home on the 30th. I have made up [my] mind, if I can keep up my courage, to start on the Saturday for Cambridge, and stay the last few days of the [British] Association there. I do so hope that you may be there then. LETTER 504. TO J.D. HOOKER. November 3rd [1864]. When I wrote to you I had not read Ramsay. (504/1. "On the Erosion of Valleys and Lakes: a Reply to Sir Roderick Murchison's Anniversary Address to the Geographical Society." "Phil. Mag." Volume XXVIII., page 293, 1864) How capitally it is written! It seems that there is nothing for style like a man's dander being put up. I think I agree largely with you about denudation--but the rocky-lake-basin theory is the part which interests me at present. It seems impossible to know how much to attribute to ice, running water, and sea. I did not suppose that Ramsay would deny that mountains had been thrown up irregularly, and that the depressions would become valleys. The grandest valleys I ever saw were at Tahiti, and here I do not believe ice has done anything; anyhow there were no erratics. I said in my S. American Geology (504/2. "Finally, the conclusion at which I have arrived with respect to the relative powers of rain, and sea-water on the land is, that the latter is by far the most efficient agent, and that its chief tendency is to widen the valleys, whilst torrents and rivers tend to deepen them and to remove the wreck of the sea's destroying action" ("Geol. Observations," pages 66, 67).) that rivers deepen and the sea widens valleys, and I am inclined largely to stick to this, adding ice to water. I am sorry to hear that Tyndall has grown dogmatic. H. Wedgwood was saying the other day that T.'s writings and speaking gave him the idea of intense conceit. I hope it is not so, for he is a grand man of science. ...I have had a prospectus and letter from Andrew Murray (504/3. See Volume II., Letters 379, 384, etc.) asking me for suggestions. I think this almost shows he is not fit for the subject, as he gives me no idea what his book will be, excepting that the printed paper shows that all animals and all plants of all groups are to be treated of. Do you know anything of his knowledge? In about a fortnight I shall have finished, except concluding chapter, my book on "Variation under Domestication"; (504/4. Published in 1868.) but then I have got to go over the whole again, and this will take me very many months. I am able to work about two hours daily. LETTER 505. TO J.D. HOOKER. Down [July, 1865]. I was glad to read your article on Glaciers, etc., in Yorkshire. You seem to have been struck with what most deeply impressed me at Glen Roy (wrong as I was on the whole subject)--viz. the marvellous manner in which every detail of surface of land had been preserved for an enormous period. This makes me a little sceptical whether Ramsay, Jukes, etc., are not a little overdoing sub-aerial denudation. In the same "Reader" (505/1. Sir J.D. Hooker wrote to Darwin, July 13th, 1865, from High Force Inn, Middleton, Teesdale: "I am studying the moraines all day long with as much enthusiasm as I am capable of after lying in bed till nine, eating heavy breakfasts, and looking forward to dinner as the summum bonum of existence." The result of his work, under the title "Moraines of the Tees Valley," appeared in the "Reader" (July 15th, 1865, page 71), of which Huxley was one of the managers or committee-men, and Norman Lockyer was scientific editor ("Life and Letters of T.H. Huxley," I., page 211). Hooker describes the moraines and other evidence of glacial action in the upper part of the Tees valley, and speaks of the effect of glaciers in determining the present physical features of the country.) there was a striking article on English and Foreign Men of Science (505/2. "British and Foreign Science," "The Reader," loc. cit., page 61. The writer of the article asserts the inferiority of English scientific workers.), and I think unjust to England except in pure Physiology; in biology Owen and R. Brown ought to save us, and in Geology we are most rich. It is curious how we are reading the same books. We intend to read Lecky and certainly to re-read Buckle--which latter I admired greatly before. I am heartily glad you like Lubbock's book so much. It made me grieve his taking to politics, and though I grieve that he has lost his election, yet I suppose, now that he is once bitten, he will never give up politics, and science is done for. Many men can make fair M.P.'s; and how few can work in science like him! I have been reading a pamphlet by Verlot on "Variation of Flowers," which seems to me very good; but I doubt whether it would be worth your reading. it was published originally in the "Journal d'Hort.," and so perhaps you have seen it. It is a very good plan this republishing separately for sake of foreigners buying, and I wish I had tried to get permission of Linn. Soc. for my Climbing paper, but it is now too late. Do not forget that you have my paper on hybridism, by Max Wichura. (505/3. Wichura, M.E., "L'Hybridisation dans le regne vegetal etudiee sur les Saules," "Arch. Sci. Phys. Nat." XXIII., page 129, 1865.) I hope you are returned to your work, refreshed like a giant by your huge breakfasts. How unlucky you are about contagious complaints with your children! I keep very weak, and had much sickness yesterday, but am stronger this morning. Can you remember how we ever first met? (505/4. See "Life and Letters," II., page 19.) It was in Park Street; but what brought us together? I have been re-reading a few old letters of yours, and my heart is very warm towards you. LETTER 506. TO C. LYELL. Down, March 8th [1866]. (506/1. In a letter from Sir Joseph Hooker to Mr. Darwin on February 21st, 1866, the following passage occurs: "I wish I could explain to you my crude notions as to the Glacial period and your position towards it. I suppose I hold this doctrine: that there was a Glacial period, but that it was not one of universal cold, because I think that the existing distribution of glaciers is sufficiently demonstrative of the proposition that by comparatively slight redispositions of sea and land, and perhaps axis of globe, you may account for all the leading palaeontological phenomena." This letter was sent by Mr. Darwin to Sir Charles Lyell, and the latter, writing on March 1st, 1866, expresses his belief that "the whole globe must at times have been superficially cooler. Still," he adds, "during extreme excentricity the sun would make great efforts to compensate in perihelion for the chill of a long winter in aphelion in one hemisphere, and a cool summer in the other. I think you will turn out to be right in regard to meridional lines of mountain-chains by which the migrations across the equator took place while there was contemporaneous tropical heat of certain lowlands, where plants requiring heat and moisture were saved from extinction by the heat of the earth's surface, which was stored up in perihelion, being prevented from radiating off freely into space by a blanket of aqueous vapour caused by the melting of ice and snow. But though I am inclined to profit by Croll's maximum excentricity for the glacial period, I consider it quite subordinate to geographical causes or the relative position of land and sea and the abnormal excess of land in polar regions." In another letter (March 5th, 1866) Lyell writes: "In the beginning of Hooker's letter to you he speaks hypothetically of a change in the earth's axis as having possibly co-operated with redistribution of land and sea in causing the cold of the Glacial period. Now, when we consider how extremely modern, zoologically and botanically, the Glacial period is proved to be, I am shocked at any one introducing, with what I may call so much levity, so organic a change as a deviation in the axis of the planet...' (see Lyell's "Principles," 1875, Chapter XIII.; also a letter to Sir Joseph Hooker printed in the "Life of Sir Charles Lyell," Volume II., page 410.)) Many thanks for your interesting letter. From the serene elevation of my old age I look down with amazement at your youth, vigour, and indomitable energy. With respect to Hooker and the axis of the earth, I suspect he is too much overworked to consider now any subject properly. His mind is so acute and critical that I always expect to hear a torrent of objections to anything proposed; but he is so candid that he often comes round in a year or two. I have never thought on the causes of the Glacial period, for I feel that the subject is beyond me; but though I hope you will own that I have generally been a good and docile pupil to you, yet I must confess that I cannot believe in change of land and water, being more than a subsidiary agent. (506/2. In Chapter XI. of the "Origin," Edition V., 1869, page 451, Darwin discusses Croll's theory, and is clearly inclined to trust in Croll's conclusion that "whenever the northern hemisphere passes through a cold period the temperature of the southern hemisphere is actually raised..." In Edition VI., page 336, he expresses his faith even more strongly. Mr. Darwin apparently sent his MS. on the climate question, which was no doubt prepared for a new edition of the "Origin," to Sir Charles. The arrival of the MS. is acknowledged in a letter from Lyell on March 10th, 1866 ("Life of Sir Charles Lyell," II., page 408), in which the writer says that he is "more than ever convinced that geographical changes...are the principal and not the subsidiary causes.") I have come to this conclusion from reflecting on the geographical distribution of the inhabitants of the sea on the opposite sides of our continents and of the inhabitants of the continents themselves. LETTER 507. TO C. LYELL. Down, September 8th [1866]. Many thanks for the pamphlet, which was returned this morning. I was very glad to read it, though chiefly as a psychological curiosity. I quite follow you in thinking Agassiz glacier-mad. (507/1. Agassiz's pamphlet, ("Geology of the Amazons") is referred to by Lyell in a letter written to Bunbury in September, 1866 ("Life of Sir Charles Lyell," II., page 409): "Agassiz has written an interesting paper on the 'Geology of the Amazons,' but, I regret to say, he has gone wild about glaciers, and has actually announced his opinion that the whole of the great valley, down to its mouth in latitude 0 deg., was filled by ice..." Agassiz published a paper, "Observations Geologiques faites dans la Vallee de l'Amazone," in the "Comptes Rendus," Volume LXIV., page 1269, 1867. See also a letter addressed to M. Marcou, published in the "Bull. Soc. Geol. France," Volume XXIV., page 109, 1866.) His evidence reduces itself to supposed moraines, which would be difficult to trace in a forest-clad country; and with respect to boulders, these are not said to be angular, and their source cannot be known in a country so imperfectly explored. When I was at Rio, I was continually astonished at the depth (sometimes 100 feet) to which the granitic rocks were decomposed in situ, and this soft matter would easily give rise to great alluvial accumulations; I well remember finding it difficult to draw a line between the alluvial matter and the softened rock in situ. What a splendid imagination Agassiz has, and how energetic he is! What capital work he would have done, if he had sucked in your "Principles" with his mother's milk. It is wonderful that he should have written such wild nonsense about the valley of the Amazon; yet not so wonderful when one remembers that he once maintained before the British Association that the chalk was all deposited at once. With respect to the insects of Chili, I knew only from Bates that the species of Carabus showed no special affinity to northern species; from the great difference of climate and vegetation I should not have expected that many insects would have shown such affinity. It is more remarkable that the birds on the broad and lofty Cordillera of Tropical S. America show no affinity with European species. The little power of diffusion with birds has often struck me as a most singular fact--even more singular than the great power of diffusion with plants. Remember that we hope to see you in the autumn. P.S.--There is a capital paper in the September number of "Annals and Magazine," translated from Pictet and Humbert, on Fossil Fish of Lebanon, but you will, I daresay, have received the original. (507/2. "Recent Researches on the Fossil Fishes of Mount Lebanon," "Ann. Mag. Nat. Hist." Volume XVIII., page 237, 1866.) It is capital in relation to modification of species; I would not wish for more confirmatory facts, though there is no direct allusion to the modification of species. Hooker, by the way, gave an admirable lecture at Nottingham; I read it in MS., or rather, heard it. I am glad it will be published, for it was capital. (507/3. Sir Joseph Hooker delivered a lecture at the Nottingham meeting of the British Association (1866) on "Insular Floras," published in the "Gardeners' Chronicle," 1867. See Letters 366-377, etc.) Sunday morning. P.S.--I have just received a letter from Asa Gray with the following passage, so that, according to this, I am the chief cause of Agassiz's absurd views:-- "Agassiz is back (I have not seen him), and he went at once down to the National Academy of Sciences, from which I sedulously keep away, and, I hear, proved to them that the Glacial period covered the whole continent of America with unbroken ice, and closed with a significant gesture and the remark: 'So here is the end of the Darwin theory.' How do you like that? "I said last winter that Agassiz was bent on covering the whole continent with ice, and that the motive of the discovery he was sure to make was to make sure that there should be no coming down of any terrestrial life from Tertiary or post-Tertiary period to ours. You cannot deny that he has done his work effectually in a truly imperial way." LETTER 508. TO C. LYELL. Down, July 14th, 1868. Mr. Agassiz's book has been read aloud to me, and I am wonderfully perplexed what to think about his precise statements of the existence of glaciers in the Ceara Mountains, and about the drift formation near Rio. (508/1. "Sur la Geologie de l'Amazone," by MM. Agassiz and Continho, "Bull. Soc. Geol. France," Volume XXV., page 685, 1868. See also "A Journey in Brazil," by Professor and Mrs. Louis Agassiz, Boston, 1868.) There is a sad want of details. Thus he never mentions whether any of the blocks are angular, nor whether the embedded rounded boulders, which cannot all be disintegrated, are scored. Yet how can so experienced an observer as A. be deceived about lateral and terminal moraines? If there really were glaciers in the Ceara Mountains, it seems to me one of the most important facts in the history of the inorganic and organic world ever observed. Whether true or not, it will be widely believed, and until finally decided will greatly interfere with future progress on many points. I have made these remarks in the hope that you will coincide. If so, do you think it would be possible to persuade some known man, such as Ramsay, or, what would be far better, some two men, to go out for a summer trip, which would be in many respects delightful, for the sole object of observing these phenomena in the Ceara Mountains, and if possible also near Rio? I would gladly put my name down for 50 pounds in aid of the expense of travelling. Do turn this over in your mind. I am so very sorry not to have seen you this summer, but for the last three weeks I have been good for nothing, and have had to stop almost all work. I hope we may meet in the autumn. LETTER 509. TO JAMES CROLL. Down, November 24th, 1868. I have read with the greatest interest the last paper which you have kindly sent me. (509/1. Croll discussed the power of icebergs as grinding and striating agents in the latter part of a paper ("On Geological Time, and the probable Dates of the Glacial and the Upper Miocene Period") published in the "Philosophical Magazine," Volume XXXV., page 363, 1868, Volume XXXVI., pages 141, 362, 1868. His conclusion was that the advocates of the Iceberg theory had formed "too extravagant notions regarding the potency of floating ice as a striating agent.") If we are to admit that all the scored rocks throughout the more level parts of the United States result from true glacier action, it is a most wonderful conclusion, and you certainly make out a very strong case; so I suppose I must give up one more cherished belief. But my object in writing is to trespass on your kindness and ask a question, which I daresay I could answer for myself by reading more carefully, as I hope hereafter to do, all your papers; but I shall feel much more confidence in a brief reply from you. Am I right in supposing that you believe that the glacial periods have always occurred alternately in the northern and southern hemispheres, so that the erratic deposits which I have described in the southern parts of America, and the glacial work in New Zealand, could not have been simultaneous with our Glacial period? From the glacial deposits occurring all round the northern hemisphere, and from such deposits appearing in S. America to be as recent as in the north, and lastly, from there being some evidence of the former lower descent of glaciers all along the Cordilleras, I inferred that the whole world was at this period cooler. It did not appear to me justifiable without distinct evidence to suppose that the N. and S. glacial deposits belonged to distinct epochs, though it would have been an immense relief to my mind if I could have assumed that this had been the case. Secondly, do you believe that during the Glacial period in one hemisphere the opposite hemisphere actually becomes warmer, or does it merely retain the same temperature as before? I do not ask these questions out of mere curiosity; but I have to prepare a new edition of my "Origin of Species," and am anxious to say a few words on this subject on your authority. I hope that you will excuse my troubling you. LETTER 510. TO J. CROLL. Down, January 31st, 1869. To-morrow I will return registered your book, which I have kept so long. I am most sincerely obliged for its loan, and especially for the MS., without which I should have been afraid of making mistakes. If you require it, the MS. shall be returned. Your results have been of more use to me than, I think, any other set of papers which I can remember. Sir C. Lyell, who is staying here, is very unwilling to admit the greater warmth of the S. hemisphere during the Glacial period in the N.; but, as I have told him, this conclusion which you have arrived at from physical considerations, explains so well whole classes of facts in distribution, that I must joyfully accept it; indeed, I go so far as to think that your conclusion is strengthened by the facts in distribution. Your discussion on the flowing of the great ice-cap southward is most interesting. I suppose that you have read Mr. Moseley's recent discussion on the force of gravity being quite insufficient to account for the downward movement of glaciers (510/1. Canon Henry Moseley, "On the Mechanical Impossibility of the Descent of Glaciers by their Weight only." "Proc. R. Soc." Volume XVII., page 202, 1869; "Phil. Mag." Volume XXXVII., page 229, 1869.): if he is right, do you not think that the unknown force may make more intelligible the extension of the great northern ice-cap? Notwithstanding your excellent remarks on the work which can be effected within the million years (510/2. In his paper "On Geological Time, and the probable Date of the Glacial and the Upper Miocene Period" ("Phil. Mag." Volume XXXV., page 363, 1868), Croll endeavours to convey to the mind some idea of what a million years really is: "Take a narrow strip of paper, an inch broad or more, and 83 feet 4 inches in length, and stretch it along the wall of a large hall, or round the walls of an apartment somewhat over 20 feet square. Recall to memory the days of your boyhood, so as to get some adequate conception of what a period of a hundred years is. Then mark off from one of the ends of the strip one-tenth of an inch. The one-tenth of an inch will then represent a hundred years, and the entire length of the strip a million of years" (loc. cit., page 375).), I am greatly troubled at the short duration of the world according to Sir W. Thomson (510/3. In a paper communicated to the Royal Society of Edinburgh, Lord Kelvin (then Sir William Thomson) stated his belief that the age of our planet must be more than twenty millions of years, but not more than four hundred millions of years ("Trans. R. Soc. Edinb." Volume XXIII., page 157, 1861, "On the Secular Cooling of the Earth."). This subject has been recently dealt with by Sir Archibald Geikie in his address as President of the Geological Section of the British Association, 1899 ("Brit. Assoc. Report," Dover Meeting, 1899, page 718).), for I require for my theoretical views a very long period BEFORE the Cambrian formation. If it would not trouble you, I should like to hear what you think of Lyell's remark on the magnetic force which comes from the sun to the earth: might not this penetrate the crust of the earth and then be converted into heat? This would give a somewhat longer time during which the crust might have been solid; and this is the argument on which Sir W. Thomson seems chiefly to rest. You seem to argue chiefly on the expenditure of energy of all kinds by the sun, and in this respect Lyell's remark would have no bearing. My new edition of the "Origin" (510/4. Fifth edition, May, 1869.) will be published, I suppose, in about two months, and for the chance of your liking to have a copy I will send one. P.S.--I wish that you would turn your astronomical knowledge to the consideration whether the form of the globe does not become periodically slightly changed, so as to account for the many repeated ups and downs of the surface in all parts of the world. I have always thought that some cosmical cause would some day be discovered. LETTER 511. TO C. LYELL. Down, July 12th [1872]. I have been glad to see the enclosed and return it. It seems to me very cool in Agassiz to doubt the recent upheaval of Patagonia, without having visited any part; and he entirely misrepresents me in saying that I infer upheaval from the form of the land, as I trusted entirely to shells embedded and on the surface. It is simply monstrous to suppose that the terraces stretching on a dead level for leagues along the coast, and miles in breadth, and covered with beds of stratified gravel, 10 to 30 feet in thickness, are due to subaerial denudation. As for the pond of salt-water twice or thrice the density of sea-water, and nearly dry, containing sea-shells in the same relative proportions as on the adjoining coast, it almost passes my belief. Could there have been a lively midshipman on board, who in the morning stocked the pool from the adjoining coast? As for glaciation, I will not venture to express any opinion, for when in S. America I knew nothing about glaciers, and perhaps attributed much to icebergs which ought to be attributed to glaciers. On the other hand, Agassiz seems to me mad about glaciers, and apparently never thinks of drift ice. I did see one clear case of former great extension of a glacier in T. del Fuego. LETTER 512. TO J. GEIKIE. (512/1. The following letter was in reply to a request from Prof. James Geikie for permission to publish Mr. Darwin's views, communicated in a previous letter (November 1876), on the vertical position of stones in gravelly drift near Southampton. Prof. Geikie wrote (July 15th, 1880): "You may remember that you attributed the peculiar position of those stones to differential movements in the drift itself arising from the slow melting of beds of frozen snow interstratified into the gravels...I have found this explanation of great service even in Scotland, and from what I have seen of the drift-gravels in various parts of southern England and northern France, I am inclined to think that it has a wide application.") Down, July 19th, 1880. Your letter has pleased me very much, and I truly feel it an honour that anything which I wrote on the drift, etc., should have been of the least use or interest to you. Pray make any use of my letter (512/2. Professor James Geikie quotes the letter in "Prehistoric Europe," London, 1881 (page 141). Practically the whole of it is given in the "Life and Letters," III., page 213.): I forget whether it was written carefully or clearly, so pray touch up any passages that you may think fit to quote. All that I have seen since near Southampton and elsewhere has strengthened my notion. Here I live on a chalk platform gently sloping down from the edge of the escarptment to the south (512/3. Id est, sloping down from the escarpment which is to the south.) (which is about 800 feet in height) to beneath the Tertiary beds to the north. The (512/4. From here to the end of the paragraph is quoted by Prof. Geikie, loc. cit., page 142.) beds of the large and broad valleys (and only of these) are covered with an immense mass of closely packed broken and angular flints; in which mass the skull of the musk-ox [musk-sheep] and woolly elephant have been found. This great accumulation of unworn flints must therefore have been made when the climate was cold, and I believe it can be accounted for by the larger valleys having been filled up to a great depth during a large part of the year with drifted frozen snow, over which rubbish from the upper parts of the platforms was washed by the summer rains, sometimes along one line and sometimes along another, or in channels cut through the snow all along the main course of the broad valleys. I suppose that I formerly mentioned to you the frequent upright position of elongated flints in the red clayey residue over the chalk, which residue gradually subsides into the troughs and pipes corroded in the solid chalk. This letter is very untidy, but I am tired. P.S. Several palaeolithic celts have recently been found in the great angular gravel-bed near Southampton in several places. LETTER 513. TO D. MACKINTOSH. Down, November 13th, 1880. Your discovery is a very interesting one, and I congratulate you on it. (513/1. "On the Precise Mode of Accumulation and Derivation of the Moel-Tryfan Shelly Deposits; on the Discovery of Similar High-level Deposits along the Eastern Slopes of the Welsh Mountains; and on the Existence of Drift-Zones, showing probable Variations in the Rate of Submergence." By D. Mackintosh, "Quart. Journ. Geol. Soc." Volume XXXVII., pages 351-69, 1881. [Read April 27th, 1881.]) I failed to find shells on Moel Tryfan, but was interested by finding ("Philosoph. Mag." 3rd series, Volume XXI., page 184) shattered rocks (513/2. In reviewing the work by previous writers on the Moel-Tryfan deposits, Mackintosh refers to Darwin's "very suggestive description of the Moel-Tryfan deposits...Under the drift he saw that the surface of the slate, TO A DEPTH OF SEVERAL FEET, HAD BEEN SHATTERED AND CONTORTED IN A VERY PECULIAR MANNER." The contortion of the slate, which Mackintosh regarded as "the most interesting of the Moel-Tryfan phenomena," had not previously been regarded as "sufficiently striking to arrest attention" by any geologist except Darwin. The Pleistocene gravel and sand containing marine shells on Moel-Tryfan, about five miles south-east of Caernarvon, have been the subject of considerable controversy. By some geologists the drift deposits have been regarded as evidence of a great submergence in post-Pliocene times, while others have explained their occurrence at a height of 1300 feet by assuming that the gravel and sand had been thrust uphill by an advancing ice-sheet. (See H.B. Woodward, "Geology of England and Wales," Edition II., 1887, pages 491, 492.) Darwin attributed the shattering and contorting of the slates below the drift to "icebergs grating over the surface.") and far-distant rounded boulders, which I attributed to the violent impact of icebergs or coast-ice. I can offer no opinion on whether the more recent changes of level in England were or were not accompanied by earthquakes. It does not seem to me a correct expression (which you use probably from haste in your note) to speak of elevations or depressions as caused by earthquakes: I suppose that every one admits that an earthquake is merely the vibration from the fractured crust when it yields to an upward or downward force. I must confess that of late years I have often begun to suspect (especially when I think of the step-like plains of Patagonia, the heights of which were measured by me) that many of the changes of level in the land are due to changes of level in the sea. (513/3. This view is an agreement with the theory recently put forward by Suess in his "Antlitz der Erde" (Prag and Leipzig, 1885). Suess believes that "the local invasions and transgressions of the continental areas by the sea" are due to "secular movements of the hydrosphere itself." (See J. Geikie, F.R.S., Presidential Address before Section E at the Edinburgh Meeting of the British Association, "Annual Report," page 794.) I suppose that there can be no doubt that when there was much ice piled up in the Arctic regions the sea would be attracted to them, and the land on the temperate regions would thus appear to have risen. There would also be some lowering of the sea by evaporation and the fixing of the water as ice near the Pole. I shall read your paper with much interest when published. LETTER 514. TO J. GEIKIE. Down, December 13th, 1880. You must allow me the pleasure of thanking you for the great interest with which I have read your "Prehistoric Europe." (514/1. "Prehistoric Europe: a Geological Sketch," London, 1881.) Nothing has struck me more than the accumulated evidence of interglacial periods, and assuredly the establishment of such periods is of paramount importance for understanding all the later changes of the earth's surface. Reading your book has brought vividly before my mind the state of knowledge, or rather ignorance, half a century ago, when all superficial matter was classed as diluvium, and not considered worthy of the attention of a geologist. If you can spare the time (though I ask out of mere idle curiosity) I should like to hear what you think of Mr. Mackintosh's paper, illustrated by a little map with lines showing the courses or sources of the erratic boulders over the midland counties of England. (514/2. "Results of a Systematic Survey, in 1878, of the Directions and Limits of Dispersion, Mode of Occurrence, and Relation to Drift-Deposits of the Erratic Blocks or Boulders of the West of England and East of Wales, including a Revision of Many Years' Previous Observations," D. Mackintosh, "Quart. Journ. Geol. Soc." Volume XXXV., page 425, 1879.) It is a little suspicious their ending rather abruptly near Wolverhampton, yet I must think that they were transported by floating ice. Fifty years ago I knew Shropshire well, and cannot remember anything like till, but abundance of gravel and sand beds, with recent marine shells. A great boulder (514/3. Mackintosh alludes (loc. cit., page 442) to felstone boulders around Ashley Heath, the highest ground between the Pennine and Welsh Hills north of the Wrekin; also to a boulder on the summit of the eminence (774 feet above sea-level), "probably the same as that noticed many years ago by Mr. Darwin." In a later paper, "On the Correlation of the Drift-Deposits of the North-West of England with those of the Midland and Eastern Counties" ("Quart. Journ. Geol. Soc." Volume XXXVI., page 178, 1880) Mackintosh mentions a letter received from Darwin, "who was the first to elucidate the boulder-transporting agency of floating ice," containing an account of the great Ashley Heath boulder, which he was the first to discover and expose,...so as to find that the block rested on fragments of New Red Sandstone, one of which was split into two and deeply scored...The facts mentioned in the letter from Mr. Darwin would seem to show that the boulder must have fallen through water from floating ice with a force sufficient to split the underlying lump of sandstone, but not sufficient to crush it.") which I had undermined on the summit of Ashley Heath, 720 (?) feet above the sea, rested on clean blocks of the underlying red sandstone. I was also greatly interested by your long discussion on the Loss (514/4. For an account of the Loss of German geologists--"a fine-grained, more or less homogeneous, consistent, non-plastic loam, consisting of an intimate admixture of clay and carbonate of lime," see J. Geikie, loc. cit., page 144 et seq.); but I do not feel satisfied that all has been made out about it. I saw much brick-earth near Southampton in some manner connected with the angular gravel, but had not strength enough to make out relations. It might be worth your while to bear in mind the possibility of fine sediment washed over and interstratified with thick beds of frozen snow, and therefore ultimately dropped irrespective of the present contour of the country. I remember as a boy that it was said that the floods of the Severn were more muddy when the floods were caused by melting snow than from the heaviest rains; but why this should be I cannot see. Another subject has interested me much--viz. the sliding and travelling of angular debris. Ever since seeing the "streams of stones" at the Falkland Islands (514/5. "Geological Observations on South America" (1846), page 19 et seq.), I have felt uneasy in my mind on this subject. I wish Mr. Kerr's notion could be fully elucidated about frozen snow. Some one ought to observe the movements of the fields of snow which supply the glaciers in Switzerland. Yours is a grand book, and I thank you heartily for the instruction and pleasure which it has given me. For heaven's sake forgive the untidiness of this whole note. LETTER 515. TO JOHN LUBBOCK [Lord Avebury]. Down, November 6th, 1881. If I had written your Address (515/1. Address delivered by Lord Avebury as President of the British Association at York in 1881. Dr. Hicks is mentioned as having classed the pre-Cambrian strata in "four great groups of immense thickness and implying a great lapse of time" and giving no evidence of life. Hicks' third formation was named by him the Arvonian ("Quart. Journ. Geol. Soc." Volume XXXVII., 1881, Proc., page 55.) (but this requires a fearful stretch of imagination on my part) I should not alter what I had said about Hicks. You have the support of the President [of the] Geological Society (515/2. Robert Etheridge.), and I think that Hicks is more likely to be right than X. The latter seems to me to belong to the class of objectors general. If Hicks should be hereafter proved to be wrong about this third formation, it would signify very little to you. I forget whether you go as far as to support Ramsay about lakes as large as the Italian ones: if so, I would myself modify the passage a little, for these great lakes have always made me tremble for Ramsay, yet some of the American geologists support him about the still larger N. American lakes. I have always believed in the main in Ramsay's views from the date of publication, and argued the point with Lyell, and am convinced that it is a very interesting step in Geology, and that you were quite right to allude to it. (515/3. "Glacial Origin of Lakes in Switzerland, Black Forest, etc." ("Quart. Journ. Geol. Soc." Volume XVIII., pages 185-204, 1862). Sir John Lubbock (Lord Avebury) gives a brief statement of Ramsay's views concerning the origin of lakes (Presidential Address, Brit. Assoc. 1881, page 22): "Prof. Ramsay divides lakes into three classes: (1) Those which are due to irregular accumulations of drift, and which are generally quite shallow; (2) those which are formed by moraines; and (3) those which occupy true basins scooped by glaciers out of the solid rocks. To the latter class belong, in his opinion, most of the great Swiss and Italian lakes...Professor Ramsay's theory seems, therefore, to account for a large number of interesting facts." Sir Archibald Geikie has given a good summary of Ramsay's theory in his "Memoir of Sir Andrew Crombie Ramsay," page 361, London, 1895.) LETTER 516. TO D. MACKINTOSH. Down, February 28th, 1882. I have read professor Geikie's essay, and it certainly appears to me that he underrated the importance of floating ice. (516/1. "The Intercrossing of Erratics in Glacial Deposits," by James Geikie, "Scottish Naturalist," 1881.) Memory extending back for half a century is worth a little, but I can remember nothing in Shropshire like till or ground moraine, yet I can distinctly remember the appearance of many sand and gravel beds--in some of which I found marine shells. I think it would be well worth your while to insist (but perhaps you have done so) on the absence of till, if absent in the Western Counties, where you find many erratic boulders. I was pleased to read the last sentence in Geikie's essay about the value of your work. (516/2. The concluding paragraph reads as follows: "I cannot conclude this paper without expressing my admiration for the long-continued and successful labours of the well-known geologist whose views I have been controverting. Although I entered my protest against his iceberg hypothesis, and have freely criticised his theoretical opinions, I most willingly admit that the results of his unwearied devotion to the study of those interesting phenomena with which he is so familiar have laid all his fellow-workers under a debt of gratitude." Mr. Darwin used to speak with admiration of Mackintosh's work, carried on as it was under considerable difficulties.) With respect to the main purport of your note, I hardly know what to say. Though no evidence worth anything has as yet, in my opinion, been advanced in favour of a living being, being developed from inorganic matter, yet I cannot avoid believing the possibility of this will be proved some day in accordance with the law of continuity. I remember the time, above fifty years ago, when it was said that no substance found in a living plant or animal could be produced without the aid of vital forces. As far as external form is concerned, Eozoon shows how difficult it is to distinguish between organised and inorganised bodies. If it is ever found that life can originate on this world, the vital phenomena will come under some general law of nature. Whether the existence of a conscious God can be proved from the existence of the so-called laws of nature (i.e., fixed sequence of events) is a perplexing subject, on which I have often thought, but cannot see my way clearly. If you have not read W. Graham's "Creed of Science," (516/3. "The Creed of Science: Religious, Moral, and Social," London, 1881.), it would, I think, interest you, and he supports the view which you are inclined to uphold. 2.IX.III. THE PARALLEL ROADS OF GLEN ROY, 1841-1880. (517/1. In the bare hilly country of Lochaber, in the Scotch Highlands, the slopes of the mountains overlooking the vale of Glen Roy are marked by narrow terraces or parallel roads, which sweep round the shoulders of the hills with "undeviating horizontality." These roads are described by Sir Archibald Geikie as having long been "a subject of wonderment and legendary story among the Highlanders, and for so many years a source of sore perplexity among men of science." (517/2. "The Scenery of Scotland," 1887, page 266.) In Glen Roy itself there are three distinct shelves or terraces, and the mountain sides of the valley of the Spean and other glens bear traces of these horizontal "roads." The first important papers dealing with the origin of this striking physical feature were those of MacCulloch (517/3. "Trans. Geol. Soc." Volume IV., page 314, 1817.) and Sir Thomas Lauder Dick (517/4. "Trans. R. Soc. Edinb." Volume IX., page 1, 1823.), in which the writers concluded that the roads were the shore-lines of lakes which once filled the Lochaber valleys. Towards the end of June 1838 Mr. Darwin devoted "eight good days" (517/5. "Life and Letters," I., page 290.) to the examination of the Lochaber district, and in the following year he communicated a paper to the Royal Society of London, in which he attributed their origin to the action of the sea, and regarded them as old sea beaches which had been raised to their present level by a gradual elevation of the Lochaber district. In 1840 Louis Agassiz and Buckland (517/6. "Edinb. New Phil. Journal," Volume XXXIII., page 236, 1842.) proposed the glacier-ice theory; they described the valleys as having been filled with lakes dammed back by glaciers which formed bars across the valleys of Glen Roy, Glen Spean, and the other glens in which the hill-sides bear traces of old lake-margins. Agassiz wrote in 1842: "When I visited the parallel roads of Glen Roy with Dr. Buckland we were convinced that the glacial theory alone satisfied all the exigencies of the phenomenon." (517/7. Ibid., page 236.) Mr. David Milne (afterwards Milne-Home) (517/8. "Trans. R. Soc. Edinb." Volume XVI., page 395, 1847.) in 1847 upheld the view that the ledges represent the shore-lines of lakes which were imprisoned in the valleys by dams of detrital material left in the glens during a submergence of 3,000 feet, at the close of the Glacial period. Chambers, in his "Ancient Sea Margins" (1848), expressed himself in agreement with Mr. Darwin's marine theory. The Agassiz-Buckland theory was supported by Mr. Jamieson (517/9. "Quart. Journ. Geol. Soc." Volume XIX., page 235, 1863.), who brought forward additional evidence in favour of the glacial barriers. Sir Charles Lyell at first (517/10. "Elements of Geology," Edition II., 1841.) accepted the explanation given by Mr. Darwin, but afterwards (517/11. "Antiquity of Man," 1863, pages 252 et seq.) came to the conclusion that the terrace-lines represent the beaches of glacial lakes. In a paper published in 1878 (517/12. "Phil. Trans. R. Soc." 1879, page 663.), Prof. Prestwich stated his acceptance of the lake theory of MacCulloch and Sir T. Lauder Dick and of the glacial theory of Agassiz, but differed from these authors in respect of the age of the lakes and the manner of formation of the roads. The view that has now gained general acceptance is that the parallel roads of Glen Roy represent the shores of a lake "that came into being with the growth of the glaciers and vanished as these melted away." (517/13. Sir Archibald Geikie, loc. cit., page 269.) Mr. Darwin became a convert to the glacier theory after the publication of Mr. Jamieson's paper. He speaks of his own paper as "a great failure"; he argued in favour of sea action as the cause of the terraces "because no other explanation was possible under our then state of knowledge." Convinced of his mistake, Darwin looked upon his error as "a good lesson never to trust in science to the principle of exclusion." (517/14. "Life and Letters," I., page 69.) LETTER 517. TO C. LYELL. [March 9th, 1841.] I have just received your note. It is the greatest pleasure to me to write or talk Geology with you... I think I have thought over the whole case without prejudice, and remain firmly convinced they [the parallel roads] are marine beaches. My principal reason for doing so is what I have urged in my paper (517/15. "Observations on the Parallel Roads of Glen Roy, and of other parts of Lochaber in Scotland, with an attempt to prove that they are of Marine Origin." "Phil. Trans. R. Soc." 1839, page 39.), the buttress-like accumulations of stratified shingle on sides of valley, especially those just below the lowest shelf in Spean Valley. 2nd. I can hardly conceive the extension of the glaciers in front of the valley of Kilfinnin, where I found a new road--where the sides of Great Glen are not very lofty. 3rd. The flat watersheds which I describe in places where there are no roads, as well as those connected with "roads." These remain unexplained. I might continue to add many other such reasons, all of which, however, I daresay would appear trifling to any one who had not visited the district. With respect to equable elevation, it cannot be a valid objection to any one who thinks of Scandinavia or the Pampas. With respect to the glacier theory, the greatest objection appears to me the following, though possibly not a sound one. The water has beyond doubt remained very long at the levels of each shelf--this is unequivocally shown by the depth of the notch or beach formed in many places in the hard mica-slate, and the large accumulations or buttresses of well-rounded pebbles at certain spots on the level of old beaches. (The time must have been immense, if formed by lakes without tides.) During the existence of the lakes their drainage must have been at the head of the valleys, and has given the flat appearance of the watersheds. All this is very clear for four of the shelves (viz., upper and lower in Glen Roy, the 800-foot one in Glen Spean, and the one in Kilfinnin), and explains the coincidence of "roads" with the watersheds more simply than my view, and as simply as the common lake theory. But how was the Glen Roy lake drained when the water stood at level of the middle "road"? It must (for there is no other exit whatever) have been drained over the glacier. Now this shelf is full as narrow in a vertical line and as deeply worn horizontally into the mountain side and with a large accumulation of shingle (I can give cases) as the other shelves. We must, therefore, on the glacier theory, suppose that the surface of the ice remained at exactly the same level, not being worn down by the running water, or the glacier moved by its own movement during the very long period absolutely necessary for a quiet lake to form such a beach as this shelf presents in its whole course. I do not know whether I have explained myself clearly. I should like to know what you think of this difficulty. I shall much like to talk over the Jura case with you. I am tired, so goodbye. LETTER 518. TO L. HORNER. Down [1846]. (518/1. It was agreed at the British Association meeting held at Southampton in 1846 "That application be made to Her Majesty's Government to direct that during the progress of the Ordnance Trigonometrical Surveys in the North of Scotland, the so-called Parallel Roads of Glen Roy and the adjoining country be accurately surveyed, with the view of determining whether they are truly parallel and horizontal, the intervening distances, and their elevations above the present sea-level" ("British Association Report," 1846, page xix). The survey was undertaken by the Government Ordnance Survey Office under Col. Sir Henry James, who published the results in 1874 ("Notes on the Parallel Roads of Glen Roy"); the map on which the details are given is sheet 63 (one-inch scale).) In following your suggestion in drawing out something about Glen Roy for the Geological Committee, I have been completely puzzled how to do it. I have written down what I should say if I had to meet the head of the Survey and wished to persuade him to undertake the task; but as I have written it, it is too long, ill expressed, seems as if it came from nobody and was going to nobody, and therefore I send it to you in despair, and beg you to turn the subject in your mind. I feel a conviction if it goes through the Geological part of Ordnance Survey it will be swamped, and as it is a case for mere accurate measurements it might, I think without offence, go to the head of the real Surveyors. If Agassiz or Buckland are on the Committee they will sneer at the whole thing and declare the beaches are those of a glacier-lake, than which I am sure I could convince you that there never was a more futile theory. I look forward to Southampton (518/2. The British Association meeting (1846).) with much interest, and hope to hear to-morrow that the lodgings are secured to us. You cannot think how thoroughly I enjoyed our geological talks, and the pleasure of seeing Mrs. Horner and yourself here. (518/3. This letter is published in the privately printed "Memoir of Leonard Horner," II., page 103.) [Here follows Darwin's Memorandum.] The Parallel Roads of Glen Roy, in Scotland, have been the object of repeated examination, but they have never hitherto been levelled with sufficient accuracy. Sir T. Lauder Dick (518/4. "On the Parallel Roads of Lochaber" (with map and plates), by Sir Thomas Lauder Dick, "Trans. R. Soc. Edinb." Volume IX., page 1, 1823.) procured the assistance of an engineer for this purpose, but owing to the want of a true ground-plan it was impossible to ascertain their exact curvature, which, as far as could be estimated, appeared equal to that of the surface of the sea. Considering how very rarely the sea has left narrow and well-defined marks of its action at any considerable height on the land, and more especially considering the remarkable observations by M. Bravais (518/5. "On the Lines of Ancient Level of the Sea in Finmark," by M. A. Bravais, translated from "Voyages de la Commission Scientifique du Nord, etc."; "Quart. Journ. Geol. Soc." Volume I., page 534, 1845.) on the ancient sea-beaches of Scandinavia, showing the they are not strictly parallel to each other, and that the movement has been greater nearer the mountains than on the coast, it appears highly desirable that the roads of Glen Roy should be examined with the utmost care during the execution of the Ordnance Survey of Scotland. The best instruments and the most accurate measurements being necessary for this end almost precludes the hope of its being ever undertaken by private individuals; but by the means at the disposal of the Ordnance, measurements would be easily made even more accurate than those of M. Bravais. It would be desirable to take two lines of the greatest possible length in the district, and at nearly right angles to each other, and to level from the beach at one extremity to that at the other, so that it might be ascertained whether the curvature does exactly correspond with that of the globe, or, if not, what is the direction of the line of greatest elevation. Much attention would be requisite in fixing on either the upper or lower edge of the ancient beaches as the standard of measurement, and in rendering this line conspicuous. The heights of the three roads, one above the other and above the level of the sea, ought to be accurately ascertained. Mr. Darwin observed one short beach-line north of Glen Roy, and he has indicated, on the authority of Sir David Brewster, others in the valley of the Spey. If these could be accurately connected, by careful measurements of their absolute heights or by levelling, with those of Glen Roy, it would make a most valuable addition to our knowledge on this subject. Although the observations here specified would probably be laborious, yet, considering how rarely such evidence is afforded in any quarter of the world, it cannot be doubted that one of the most important problems in Geology--namely, the exact manner in which the crust of the earth rises in mass--would be much elucidated, and a great service done to geological science. LETTER 519. R. CHAMBERS TO D. MILNE-HOME. St. Andrews, September 7th, 1847. I have had a letter to-day from Mr. Charles Darwin, beseeching me to obtain for him a copy of your paper on Glen Roy. (519/1. No doubt Mr. Milne's paper "On the Parallel Roads of Lochaber," "Trans. R. Soc. Edinb." Volume XVI., page 395, 1849. [Read March 1st and April 5th, 1847.]) I am sure you will have pleasure in sending him one; his address is "Down, Farnborough, Kent." I have again read over your paper carefully, and feel assured that the careful collection and statement of facts which are found in it must redound to your credit with all candid persons. The suspicions, however, which I obtained some time ago as to land-straits and heights of country being connected with sea-margins and their ordinary memorials still possesses me, and I am looking forward to some means of further testing the Glen Roy mystery. If my suspicion turn out true, I shall at once be regretful on your account, and shall feel it as a great check and admonition to myself not to be too confident about anything in science till it has been proved over and over again. The ground hereabouts is now getting clear of the crops; perhaps when I am in town a few days hence we may be able to make some appointment for an examination of the beaches of the district, my list of which has been greatly enlarged during the last two months. LETTER 520. TO R. CHAMBERS. September 11th, 1847. I hope you will read the first part of my paper before you go [to Glen Roy], and attend to the manner in which the lines end in Glen Collarig. I wish Mr. Milne had read it more carefully. He misunderstands me in several respects, but [I] suppose it is my own fault, for my paper is most tediously written. Mr. Milne fights me very pleasantly, and I plead guilty to his rebuke about "demonstration." (520/1. See Letter 521, note.) I do not know what you think; but Mr. Milne will think me as obstinate as a pig when I say that I think any barriers of detritus at the mouth of Glen Roy, Collarig and Glaster more utterly impossible than words can express. I abide by all that I have written on that head. Conceive such a mass of detritus having been removed, without great projections being left on each side, in the very close proximity to every little delta preserved on the lines of the shelves, even on the shelf 4, which now crosses with uniform breadth the spot where the barrier stood, with the shelves dying gradually out, etc. To my mind it is monstrous. Oddly enough, Mr. Milne's description of the mouth of Loch Treig (I do not believe that valley has been well examined in its upper end) leaves hardly a doubt that a glacier descended from it, and, if the roads were formed by a lake of any kind, I believe it must have been an ice-lake. I have given in detail to Lyell my several reasons for not thinking ice-lakes probable (520/2. Mr. Darwin gives some arguments against the glacier theory in the letter (517) to Sir Charles Lyell; but the letter alluded to is no doubt the one written to Lyell on "Wednesday, 8th" (Letter 522), in which the reasons are fully stated.); but to my mind they are incomparably more probable than detritus of rock-barriers. Have you ever attended to glacier action? After having seen N. Wales, I can no more doubt the former existence of gigantic glaciers than I can the sun in the heaven. I could distinguish in N. Wales to a certain extent icebergs from glacier action (Lyell has shown that icebergs at the present day score rocks), and I suspect that in Lochaber the two actions are united, and that the scored rock on the watersheds, when tideways, were rubbed and bumped by half-stranded icebergs. You will, no doubt, attend to Glen Glaster. Mr. Milne, I think, does not mention whether shelf 4 enters it, which I should like to know, and especially he does not state whether rocks worn on their upper faces are found on the whole 212 [feet] vertical course of this Glen down to near L. Loggan, or whether only in the upper part; nor does he state whether these rocks are scored, or polished, or moutonnees, or whether there are any "perched" boulders there or elsewhere. I suspect it would be difficult to distinguish between a river-bed and tidal channel. Mr. Milne's description of the Pass of Mukkul, expanding to a width of several hundred yards 21 feet deep in the shoalest part, and with a worn islet in the middle, sounds to me much more like a tidal channel than a river-bed. There must have been, on the latter view, plenty of fresh water in those days. With respect to the coincidence of the shelves with the now watersheds, Mr. Milne only gives half of my explanation. Please read page 65 of my paper. (520/3. "Observations on the Parallel Roads of Glen Roy, and of other Parts of Lochaber in Scotland, with an Attempt to Prove that they are of Marine Origin." "Phil. Trans. R. Soc." 1839, page 39. [Read February 7th, 1839.]) I allude only to the head of Glen Roy and Kilfinnin as silted up. I did not know Mukkul Pass; and Glen Roy was so much covered up that I did not search it well, as I was not able to walk very well. It has been an old conjectural belief of mine that a rising surface becomes stationary, not suddenly, but by the movement becoming very slow. Now, this would greatly aid the tidal currents cutting down the passes between the mountains just before, and to the level of, the stationary periods. The currents in the fiords in T. del Fuego in a narrow crooked part are often most violent; in other parts they seem to silt up. Shall you do any levelling? I believe all the levelling has been [done] in Glen Roy, nearly parallel to the Great Glen of Scotland. For inequalities of elevation, the valley of the Spean, at right angles to the apparent axes of elevation, would be the one to examine. If you go to the head of Glen Roy, attend to the apparent shelf above the highest one in Glen Roy, lying on the south side of Loch Spey, and therefore beyond the watershed of Glen Roy. It would be a crucial case. I was too unwell on that day to examine it carefully, and I had no levelling instruments. Do these fragments coincide in level with Glen Gluoy shelf? MacCulloch talks of one in Glen Turret above the shelf. I could not see it. These would be important discoveries. But I will write no more, and pray your forgiveness for this long, ill-written outpouring. I am very glad you keep to your subject of the terraces. I have lately observed that you have one great authority (C. Prevost), [not] that authority signifies a [farthing?] on your side respecting your heretical and damnable doctrine of the ocean falling. You see I am orthodox to the burning pitch. LETTER 521. TO D. MILNE-HOME. Down, [September] 20th, [1847]. I am much obliged by your note. I returned from London on Saturday, and I found then your memoir (521/1. "On the Parallel Roads of Lochaber, with Remarks on the Change of Relative Levels of Sea and Land in Scotland, and on the Detrital Deposits in that Country," "Trans. R. Soc. Edinb." Volume XVI., page 395, 1849. [Read March 1st and April 5th, 1847.]), which I had not then received, owing to the porter having been out when I last sent to the Geological Society. I have read your paper with the greatest interest, and have been much struck with the novelty and importance of many of your facts. I beg to thank you for the courteous manner in which you combat me, and I plead quite guilty to your rebuke about demonstration. (521/2. Mr. Milne quotes a passage from Mr. Darwin's paper ("Phil. Trans. R. Soc." 1839, page 56), in which the latter speaks of the marine origin of the parallel roads of Lochaber as appearing to him as having been demonstrated. Mr. Milne adds: "I regret that Mr. Darwin should have expressed himself in these very decided and confident terms, especially as his survey was incomplete; for I venture to think that it can be satisfactorily established that the parallel roads of Lochaber were formed by fresh-water lakes" (Milne, loc. cit., page 400).) You have misunderstood my paper on a few points, but I do not doubt that is owing to its being badly and tediously written. You will, I fear, think me very obstinate when I say that I am not in the least convinced about the barriers (521/3. Mr. Milne believed that the lower parts of the valleys were filled with detritus, which constituted barriers and thus dammed up the waters into lakes.): they remain to me as improbable as ever. But the oddest result of your paper on me (and I assure you, as far as I know myself, it is not perversity) is that I am very much staggered in favour of the ice-lake theory of Agassiz and Buckland (521/4. Agassiz and Buckland believed that the lakes which formed the "roads" were confined by glaciers or moraines. See "The Glacial Theory and its Recent Progress," by Louis Agassiz, "Edinb. New Phil. Journ." Volume XXXIII., page 217, 1842 (with map).): until I read your important discovery of the outlet in Glen Glaster I never thought this theory at all tenable. (521/5. Mr. Milne discovered that the middle shelf of Glen Roy, which Mr. Darwin stated was "not on a level with any watershed" (Darwin, loc. cit., page 43), exactly coincided with a watershed at the head of Glen Glaster (Milne, loc. cit., page 398).) Now it appears to me that a very good case can be made in its favour. I am not, however, as yet a believer in the ice-lake theory, but I tremble for the result. I have had a good deal of talk with Mr. Lyell on the subject, and from his advice I am going to send a letter to the "Scotsman," in which I give briefly my present impression (though there is not space to argue with you on such points as I think I could argue), and indicate what points strike me as requiring further investigation with respect, chiefly, to the ice-lake theory, so that you will not care about it... P.S.--Some facts mentioned in my "Geology of S. America," page 24 (521/6. The creeks which penetrate the western shores of Tierra del Fuego are described as "almost invariably much shallower close to the open sea at their mouths than inland...This shoalness of the sea-channels near their entrances probably results from the quantity of sediment formed by the wear and tear of the outer rocks exposed to the full force of the open sea. I have no doubt that many lakes--for instance, in Scotland--which are very deep within, and are separated from the sea apparently only by a tract of detritus, were originally sea-channels, with banks of this nature near their mouths, which have since been upheaved" ("Geol. Obs. S. America," page 24, footnote.), with regard to the shoaling of the deep fiords of T. del Fuego near their mouths, and which I have remarked would tend, with a little elevation, to convert such fiords into lakes with a great mound-like barrier of detritus at their mouths, might, possibly, have been of use to you with regard to the lakes of Glen Roy. LETTER 522. TO C. LYELL. Down, Wednesday, 8th. Many thanks for your paper. (522/1. "On the Ancient Glaciers of Forfarshire." "Proc. Geol. Soc." Volume III., page 337, 1840.) I do admire your zeal on a subject on which you are not immediately at work. I will give my opinion as briefly as I can, and I have endeavoured my best to be honest. Poor Mrs. Lyell will have, I foresee, a long letter to read aloud, but I will try to write better than usual. Imprimis, it is provoking that Mr. Milne (522/2. "On the Parallel Roads of Lochaber, etc." "Trans. R. Soc. Edinb." Volume XVI., page 395, 1849. [Read March 1st and April 5th, 1847.]) has read my paper (522/3. "Observations on the Parallel Roads of Glen Roy, etc." "Phil. Trans. R. Soc." 1839, page 39. [Read February 7th, 1839.].) with little attention, for he makes me say several things which I do not believe--as, that the water sunk suddenly! (page 10), that the Valley of Glen Roy, page 13, and Spean was filled up with detritus to level of the lower shelf, against which there is, I conceive, good evidence, etc., but I suppose it is the consequence of my paper being most tediously written. He gives me a just snub for talking of demonstration, and he fights me in a very pleasant manner. Now for business. I utterly disbelieve in the barriers (522/4. See note, Letter 521.) for his lakes, and think he has left that point exactly where it was in the time of MacCulloch (522/5. "On the Parallel Roads of Glen Roy." "Geol. Trans." Volume IV., page 314, 1817 (with several maps and sections).) and Dick. (522/6. "On the Parallel Roads of Lochaber." "Trans. R. Soc. Edinb." Volume IX., page 1, 1823.) Indeed, in showing that there is a passage at Glen Glaster at the level of the intermediate shelf, he makes the difficulty to my mind greater. (522/7. See Letter 521, note.) When I think of the gradual manner in which the two upper terraces die out at Glen Collarig and at the mouth of Glen Roy, the smooth rounded form of the hills there, and the lower shelf retaining its usual width where the immense barrier stood, I can deliberately repeat "that more convincing proofs of the non-existence of the imaginary Loch Roy could scarcely have been invented with full play given to the imagination," etc.: but I do not adhere to this remark with such strength when applied to the glacier-lake theory. Oddly, I was never at all staggered by this theory until now, having read Mr. Milne's argument against it. I now can hardly doubt that a great glacier did emerge from Loch Treig, and this by the ice itself (not moraine) might have blocked up the three outlets from Glen Roy. I do not, however, yet believe in the glacier theory, for reasons which I will presently give. There are three chief hostile considerations in Mr. Milne's paper. First, the Glen [shelf?], not coinciding in height with the upper one [outlet?], from observations giving 12 feet, 15 feet, 29 feet, 23 feet: if the latter are correct the terrace must be quite independent, and the case is hostile; but Mr. Milne shows that there is one in Glen Roy 14 feet below the upper one, and a second one again (which I observed) beneath this, and then we come to the proper second shelf. Hence there is no great improbability in an independent shelf having been found in Glen Gluoy. This leads me to Mr. Milne's second class of facts (obvious to every one), namely the non-extension of the three shelves beyond Glen Roy; but I abide by what I have written on that point, and repeat that if in Glen Roy, where circumstances have been so favourable for the preservation or formation of the terraces, a terrace could be formed quite plain for three-quarters of a mile with hardly a trace elsewhere, we cannot argue, from the non-existence of shelves, that water did not stand at the same levels in other valleys. Feeling absolutely convinced that there was no barrier of detritus at the mouth of Glen Roy, and pretty well convinced that there was none of ice, the manner in which the terraces die out when entering Glen Spean, which must have been a tideway, shows on what small circumstances the formation of these shelves depended. With respect to the non-existence of shelves in other parts of Scotland, Mr. Milne shows that many others do exist, and their heights above the sea have not yet been carefully measured, nor have even those of Glen Roy, which I suspect are all 100 feet too high. Moreover, according to Bravais (522/8. "On the Lines of Ancient Level of the Sea in Finmark." By A. Bravais, Member of the Scientific Commission of the North. "Quart. Journ. Geol. Soc." Volume I., page 534, 1845 (a translation).), we must not feel sure that either the absolute height or the intermediate heights between the terraces would be at all the same at distant points. In levelling the terraces in Lochaber, all, I believe, have been taken in Glen Roy, nearly N. and S. There should be levels taken at right angles to this line and to the Great Glen of Scotland or chief line of elevation. Thirdly, the nature of the outlets from the supposed lakes. This appears to me the best and newest part of the paper. If Sir James Clark would like to attend to any particular points, direct his attention to this: especially to follow Glen Glaster from Glen Roy to L. Laggan. Mr. Milne describes this as an old and great river-course with a fall of 212 feet. He states that the rocks are smooth on upper face and rough on lower, but he does not mention whether this character prevails throughout the whole 212 vertical feet--a most important consideration; nor does he state whether these rocks are polished or scratched, as might have happened even to a considerable depth beneath the water (Mem. great icebergs in narrow fiords of T. del Fuego (522/9. In the "Voyage of the 'Beagle'" a description is given of the falling of great masses of ice from the icy cliffs of the glaciers with a crash that "reverberates like the broadside of a man-of-war, through the lonely channels" which intersect the coast-line of Tierra del Fuego. Loc. cit., page 246.)) by the action of icebergs, for that icebergs transported boulders on to terraces, I have no doubt. Mr. Milne's description of the outlets of his lake sound to me more like tidal channels, nor does he give any arguments how such are to be distinguished from old river-courses. I cannot believe in the body of fresh water which must, on the lake theory, have flowed out of them. At the Pass of Mukkul he states that the outlet is 70 feet wide and the rocky bottom 21 feet below the level of the shelf, and that the gorge expands to the eastwards into a broad channel of several hundred yards in width, divided in the middle by what has formerly been a rocky islet, against which the waters of this large river had chafed in issuing from the pass. We know the size of the river at the present day which would flow out through this pass, and it seems to me (and in the other given cases) to be as inadequate; the whole seems to me far easier explained by a tideway than by a formerly more humid climate. With respect to the very remarkable coincidence between the shelves and the outlets (rendered more remarkable by Mr. Milne's discovery of the outlet to the intermediate shelf at Glen Glaster (522/10. See Letter 521, note.)), Mr. Milne gives only half of my explanation; he alludes to (and disputes) the smoothing and silting-up action, which I still believe in. I state: If we consider what must take place during the gradual rise of a group of islands, we shall have the currents endeavouring to cut down and deepen some shallow parts in the channels as they are successively brought near the surface, but tending from the opposition of tides to choke up others with littoral deposits. During a long interval of rest, from the length of time allowed to the above processes, the tendency would often prove effective, both in forming, by accumulation of matter, isthmuses, and in keeping open channels. Hence such isthmuses and channels just kept open would oftener be formed at the level which the waters held at the interval of rest, than at any other (page 65). I look at the Pass of Mukkul (21 feet deep, Milne) as a channel just kept open, and the head of Glen Roy (where there is a great bay silted up) and of Kilfinnin (at both which places there are level-topped mounds of detritus above the level of the terraces) as instances of channels filled up at the stationary levels. I have long thought it a probable conjecture that when a rising surface becomes stationary it becomes so, not at once, but by the movements first becoming very slow; this would greatly favour the cutting down many gaps in the mountains to the level of the stationary periods. GLACIER THEORY. If a glacialist admitted that the sea, before the formation of the terraces, covered the country (which would account for land-straits above level of terraces), and that the land gradually emerged, and if he supposed his lakes were banked by ice alone, he would make out, in my opinion, the best case against the marine origin of the terraces. From the scattered boulders and till, you and I must look at it as certain that the sea did cover the whole country, and I abide quite by my arguments from the buttresses, etc., that water of some kind receded slowly from the valleys of Lochaber (I presume Mr. Milne admits this). Now, I do not believe in the ice-lake theory, from the following weak but accumulating reasons: because, 1st, the receding water must have been that of a lake in Glen Spean, and of the sea in the other valleys of Scotland, where I saw similar buttresses at many levels; 2nd, because the outlets of the supposed lakes as already stated seem, from Mr. Milne's statements, too much worn and too large; 3rd, when the lake stood at the three-quarters of a mile shelf the water from it must have flowed over ice itself for a very long time, and kept at the same exact level: certainly this shelf required a long time for its formation; 4th, I cannot believe a glacier would have blocked up the short, very wide valley of Kilfinnin, the Great Glen of Scotland also being very low there; 5th, the country at some places where Mr. Milne has described terraces is not mountainous, and the number of ice-lakes appears to me very improbable; 6th, I do not believe any lake could scoop the rocks so much as they are at the entrance to Loch Treig or cut them off at the head of Upper Glen Roy; 7th, the very gradual dying away of the terraces at the mouth of Glen Roy does not look like a barrier of any kind; 8th, I should have expected great terminal moraines across the mouth of Glen Roy, Glen Collarig, and Glaster, at least at the bottom of the valleys. Such, I feel pretty sure, do not exist. I fear I must have wearied you with the length of this letter, which I have not had time to arrange properly. I could argue at great length against Mr. Milne's theory of barriers of detritus, though I could help him in one way--viz., by the soundings which occur at the entrances of the deepest fiords in T. del Fuego. I do not think he gives the smallest satisfaction with respect to the successive and comparatively sudden breakage of his many lakes. Well, I enjoyed my trip to Glen Roy very much, but it was time thrown away. I heartily wish you would go there; it should be some one who knows glacier and iceberg action, and sea action well. I wish the Queen would command you. I had intended being in London to-morrow, but one of my principal plagues will, I believe, stop me; if I do I will assuredly call on you. I have not yet read Mr. Milne on Elevation (522/11. "On a Remarkable Oscillation of the Sea, observed at Various Places on the Coasts of Great Britain in the First Week of July, 1843." "Trans. R. Soc. Edinb." Volume XV., page 609, 1844.), so will keep his paper for a day or two. P.S.--As you cannot want this letter, I wish you would return it to me, as it will serve as a memorandum for me. Possibly I shall write to Mr. Chambers, though I do not know whether he will care about what I think on the subject. This letter is too long and ill-written for Sir J. Clark. LETTER 523. TO LADY LYELL. [October 4th, 1847.] I enclose a letter from Chambers, which has pleased me very much (which please return), but I cannot feel quite so sure as he does. If the Lochaber and Tweed roads really turn out exactly on a level, the sea theory is proved. What a magnificent proof of equality of elevation, which does not surprise me much; but I fear I see cause of doubt, for as far as I remember there are numerous terraces, near Galashiels, with small intervals of height, so that the coincidence of height might be cooked. Chambers does not seem aware of one very striking coincidence, viz., that I made by careful measurement my Kilfinnin terrace 1202 feet above sea, and now Glen Gluoy is 1203 feet, according to the recent more careful measurements. Even Agassiz (523/1. "On the Glacial Theory," by Louis Agassiz, "Edinb. New Phil. Journ." Volume XXXIII., page 217, 1842. The parallel terraces are dealt with by Agassiz, pages 236 et seq.) would be puzzled to block up Glen Gluoy and Kilfinnin by the same glacier, and then, moreover, the lake would have two outlets. With respect to the middle terrace of Glen Roy--seen by Chambers in the Spean (figured by Agassiz, and seen by myself but not noticed, as I thought it might have been a sheep track)--it might yet have been formed on the ice-lake theory by two independent glaciers going across the Spean, but it is very improbable that two such immense ones should not have been united into one. Chambers, unfortunately, does not seem to have visited the head of the Spey, and I have written to propose joining funds and sending some young surveyor there. If my letter is published in the "Scotsman," how Buckland (523/2. Professor Buckland may be described as joint author, with Agassiz, of the Glacier theory.), as I have foreseen, will crow over me: he will tell me he always knew that I was wrong, but now I shall have rather ridiculously to say, "but I am all right again." I have been a good deal interested in Miller (523/3. Hugh Miller's "First Impressions of England and its People," London, 1847.), but I find it not quick reading, and Emma has hardly begun it yet. I rather wish the scenic descriptions were shorter, and that there was a little less geologic eloquence. Lyell's picture now hangs over my chimneypiece, and uncommonly glad I am to have it, and thank you for it. LETTER 524. TO C. LYELL. Down, September 6th [1861]. I think the enclosed is worth your reading. I am smashed to atoms about Glen Roy. My paper was one long gigantic blunder from beginning to end. Eheu! Eheu! (524/1. See "Life and Letters," I., pages 68, 69, also pages 290, 291.) LETTER 525. TO C. LYELL. Down, September 22nd [1861]. I have read Mr. Jamieson's last letter, like the former ones, with very great interest. (525/1. Mr. Jamieson visited Glen Roy in August 1861 and in July 1862. His paper "On the Parallel Roads of Glen Roy, and their Place in the History of the Glacial Period," was published in the "Quarterly Journal of the Geological Society" in 1863, Volume XIX., page 235. His latest contribution to this subject was published in the "Quarterly Journal," Volume XLVIII., page 5, 1892.) What a problem you have in hand! It beats manufacturing new species all to bits. It would be a great personal consolation to me if Mr. J. can admit the sloping Spean terrace to be marine, and would remove one of my greatest difficulties--viz. the vast contrast of Welsh and Lochaber valleys. But then, as far as I dare trust my observations, the sloping terraces ran far up the Roy valley, so as to reach not far below the lower shelf. If the sloping fringes are marine and the shelves lacustrine, all I can say is that nature has laid a shameful trap to catch an unwary wretch. I suppose that I have underrated the power of lakes in producing pebbles; this, I think, ought to be well looked to. I was much struck in Wales on carefully comparing the glacial scratches under a lake (formed by a moraine and which must have existed since the Glacial epoch) and above water, and I could perceive NO difference. I believe I saw many such beds of good pebbles on level of lower shelf, which at the time I could not believe could have been found on shores of lake. The land-straits and little cliffs above them, to which I referred, were quite above the highest shelf; they may be of much more ancient date than the shelves. Some terrace-like fringes at head of the Spey strike me as very suspicious. Mr. J. refers to absence of pebbles at considerable heights: he must remember that every storm, every deer, every hare which runs tends to roll pebbles down hill, and not one ever goes up again. I may mention that I particularly alluded to this on S. Ventanao (525/2. "Geolog. Obs. on South America," page 79. "On the flanks of the mountains, at a height of 300 or 400 feet above the plain, there were a few small patches of conglomerate and breccia, firmly cemented by ferruginous matter to the abrupt and battered face of the quartz--traces being thus exhibited of ancient sea-action.") in N. Patagonia, a great isolated rugged quartz-mountain 3,000 feet high, and I could find not one pebble except on one very small spot, where a ferruginous spring had firmly cemented a few to the face of mountain. If the Lochaber lakes had been formed by an ice-period posterior to the (marine?) sloping terraces in the Spean, would not Mr. J. have noticed gigantic moraines across the valley opposite the opening of Lake Treig? I go so far as not to like making the elevation of the land in Wales and Scotland considerably different with respect to the ice-period, and still more do I dislike it with respect to E. and W. Scotland. But I may be prejudiced by having been so long accustomed to the plains of Patagonia. But the equality of level (barring denudation) of even the Secondary formations in Britain, after so many ups and downs, always impresses my mind, that, except when the crust-cracks and mountains are formed, movements of elevation and subsidence are generally very equable. But it is folly my scribbling thus. You have a grand problem, and heaven help you and Mr. Jamieson through it. It is out of my line nowadays, and above and beyond me. LETTER 526. TO J.D. HOOKER. Down, September 28th [1861]. It is, I believe, true that Glen Roy shelves (I remember your Indian letter) were formed by glacial lakes. I persuaded Mr. Jamieson, an excellent observer, to go and observe them; and this is his result. There are some great difficulties to be explained, but I presume this will ultimately be proved the truth... LETTER 527. TO C. LYELL. Down, October 1st [1861]. Thank you for the most interesting correspondence. What a wonderful case that of Bedford. (527/1. No doubt this refers to the discovery of flint implements in the Valley of the Ouse, near Bedford, in 1861 (see Lyell's "Antiquity of Man," pages 163 et seq., 1863.) I thought the problem sufficiently perplexing before, but now it beats anything I ever heard of. Far from being able to give any hypothesis for any part, I cannot get the facts into my mind. What a capital observer and reasoner Mr. Jamieson is. The only way that I can reconcile my memory of Lochaber with the state of the Welsh valleys is by imagining a great barrier, formed by a terminal moraine, at the mouth of the Spean, which the river had to cut slowly through, as it drained the lowest lake after the Glacial period. This would, I can suppose, account for the sloping terraces along the Spean. I further presume that sharp transverse moraines would not be formed under the waters of the lake, where the glacier came out of L. Treig and abutted against the opposite side of the valley. A nice mess I made of Glen Roy! I have no spare copy of my Welsh paper (527/2. "Notes on the Effects produced by the Ancient Glaciers of Caernarvonshire, and on the Boulders transported by Floating Ice," "Edinb. New Phil. Journ." Volume XXXIII., page 352, 1842.); it would do you no good to lend it. I suppose I thought that there must have been floating ice on Moel Tryfan. I think it cannot be disputed that the last event in N. Wales was land-glaciers. I could not decide where the action of land-glaciers ceased and marine glacial action commenced at the mouths of the valleys. What a wonderful case the Bedford case. Does not the N. American view of warmer or more equable period, after great Glacial period, become much more probable in Europe? But I am very poorly to-day, and very stupid, and hate everybody and everything. One lives only to make blunders. I am going to write a little book for Murray on Orchids (527/3. "On the Various Contrivances by which Orchids are Fertilised by Insects," London, 1862.), and to-day I hate them worse than everything. So farewell, in a sweet frame of mind. LETTER 528. TO C. LYELL. Down, October 14th [1861]. I return Jamieson's capital letter. I have no comments, except to say that he has removed all my difficulties, and that now and for evermore I give up and abominate Glen Roy and all its belongings. It certainly is a splendid case, and wonderful monument of the old Ice-period. You ought to give a woodcut. How many have blundered over those horrid shelves! That was a capital paper by Jamieson in the last "Geol. Journal." (528/1. "On the Drift and Rolled Gravel of the North of Scotland," "Quart. Journ. Geol. Soc." Volume XVI., page 347, 1860.) I was never before fully convinced of the land glacialisation of Scotland before, though Chambers tried hard to convince me. I must say I differ rather about Ramsay's paper; perhaps he pushes it too far. (528/2. "On the Glacial Origin of Certain Lakes, etc." "Quart. Journ. Geol. Soc." Volume XVIII., page 185. See Letter 503.) It struck me the more from remembering some years ago marvelling what could be the meaning of such a multitude of lakes in Friesland and other northern districts. Ramsay wrote to me, and I suggested that he ought to compare mountainous tropical regions with northern regions. I could not remember many lakes in any mountainous tropical country. When Tyndall talks of every valley in Switzerland being formed by glaciers, he seems to forget there are valleys in the tropics; and it is monstrous, in my opinion, the accounting for the Glacial period in the Alps by greater height of mountains, and their lessened height, if I understand, by glacial erosion. "Ne sutor ultra crepidam," I think, applies in this case to him. I am hard at work on "Variation under Domestication." (528/3. Published 1868.) P.S.--I am rather overwhelmed with letters at present, and it has just occurred to me that perhaps you will forward my note to Mr. Jamieson; as it will show that I entirely yield. I do believe every word in my Glen Roy paper is false. LETTER 529. TO C. LYELL. Down, October 20th [1861]. Notwithstanding the orchids, I have been very glad to see Jamieson's letter; no doubt, as he says, certainty will soon be reached. With respect to the minor points of Glen Roy, I cannot feel easy with a mere barrier of ice; there is so much sloping, stratified detritus in the valleys. I remember that you somewhere have stated that a running stream soon cuts deeply into a glacier. I have been hunting up all old references and pamphlets, etc., on shelves in Scotland, and will send them off to Mr. J., as they possibly may be of use to him if he continues the subject. The Eildon Hills ought to be specially examined. Amongst MS. I came across a very old letter from me to you, in which I say: "If a glacialist admitted that the sea, before the formation of the shelves, covered the country (which would account for the land-straits above the level of the shelves), and if he admitted that the land gradually emerged, and if he supposed that his lakes were banked up by ice alone, he would make out, in my opinion, the best case against the marine origin of the shelves." (529/1. See Letter 522.) This seems very much what you and Mr. J. have come to. The whole glacial theory is really a magnificent subject. LETTER 530. TO C. LYELL. Down, April 1st [1862]. I am not quite sure that I understand your difficulty, so I must give what seems to me the explanation of the glacial lake theory at some little length. You know that there is a rocky outlet at the level of all the shelves. Please look at my map. (530/1. The map accompanying Mr. Darwin's paper in the "Phil. Trans. R. Soc." 1839.) I suppose whole valley of Glen Spean filled with ice; then water would escape from an outlet at Loch Spey, and the highest shelf would be first formed. Secondly, ice began to retreat, and water will flow for short time over its surface; but as soon as it retreated from behind the hill marked Craig Dhu, where the outlet on level of second shelf was discovered by Milne (530/2. See note, Letter 521.), the water would flow from it and the second shelf would be formed. This supposes that a vast barrier of ice still remains under Ben Nevis, along all the lower part of the Spean. Lastly, I suppose the ice disappeared everywhere along L. Loggan, L. Treig, and Glen Spean, except close under Ben Nevis, where it still formed a barrier, the water flowing out at level of lowest shelf by the Pass of Mukkul at head of L. Loggan. This seems to me to account for everything. It presupposes that the shelves were formed towards the close of the Glacial period. I come up to London to read on Thursday a short paper at the Linnean Society. Shall I call on Friday morning at 9.30 and sit half an hour with you? Pray have no scruple to send a line to Queen Anne Street to say "No" if it will take anything out of you. If I do not hear, I will come. LETTER 531. TO J. PRESTWICH. Down, January 3rd, 1880. You are perfectly right. (531/1. Prof. Prestwich's paper on Glen Roy was published in the "Phil. Trans. R. Soc." for 1879, page 663.) As soon as I read Mr. Jamieson's article on the parallel roads, I gave up the ghost with more sighs and groans than on almost any other occasion in my life. 2.IX.IV. CORAL REEFS, FOSSIL AND RECENT, 1841-1881. LETTER 532. TO C. LYELL. Shrewsbury, Tuesday, 6th [July, 1841]. Your letter was forwarded me here. I was the more glad to receive it, as I never dreamed of your being able to find time to write, now that you must be so very busy; and I had nothing to tell you about myself, else I should have written. I am pleased to hear how extensive and successful a trip you appear to have made. You must have worked hard, and got your Silurian subject well in your head, to have profited by so short an excursion. How I should have enjoyed to have followed you about the coral-limestone. I once was close to Wenlock (532/1. The Wenlock limestone (Silurian) contains an abundance of corals. "The rock seems indeed to have been formed in part by massive sheets and bunches of coral" (Geikie, "Text-book of Geology," 1882, page 678.), something such as you describe, and made a rough drawing, I remember, of the masses of coral. But the degree in which the whole mass was regularly stratified, and the quantity of mud, made me think that the reefs could never have been like those in the Pacific, but that they most resembled those on the east coast of Africa, which seem (from charts and descriptions) to confine extensive flats and mangrove swamps with mud, or like some imperfect ones about the West India Islands, within the reefs of which there are large swamps. All the reefs I have myself seen could be associated only with nearly pure calcareous rocks. I have received a description of a reef lying some way off the coast near Belize (terra firma), where a thick bed of mud seems to have invaded and covered a coral reef, leaving but very few islets yet free from it. But I can give you no precise information without my notes (even if then) on these heads... Bermuda differs much from any other island I am acquainted with. At first sight of a chart it resembles an atoll; but it differs from this structure essentially in the gently shelving bottom of the sea all round to some distance; in the absence of the defined circular reefs, and, as a consequence, of the defined central pool or lagoon; and lastly, in the height of the land. Bermuda seems to be an irregular, circular, flat bank, encrusted with knolls and reefs of coral, with land formed on one side. This land seems once to have been more extensive, as on some parts of the bank farthest removed from the island there are little pinnacles of rock of the same nature as that of the high larger islands. I cannot pretend to form any precise notion how the foundation of so anomalous an island has been produced, but its whole history must be very different from that of the atolls of the Indian and Pacific oceans--though, as I have said, at first glance of the charts there is a considerable resemblance. LETTER 533. TO C. LYELL. [1842.] Considering the probability of subsidence in the middle of the great oceans being very slow; considering in how many spaces, both large ones and small ones (within areas favourable to the growth of corals), reefs are absent, which shows that their presence is determined by peculiar conditions; considering the possible chance of subsidence being more rapid than the upward growth of the reefs; considering that reefs not very rarely perish (as I cannot doubt) on part, or round the whole, of some encircled islands and atolls: considering these things, I admit as very improbable that the polypifers should continue living on and above the same reef during a subsidence of very many thousand feet; and therefore that they should form masses of enormous thickness, say at most above 5,000 feet. (533/1. "...As we know that some inorganic causes are highly injurious to the growth of coral, it cannot be expected that during the round of change to which earth, air, and water are exposed, the reef-building polypifers should keep alive for perpetuity in any one place; and still less can this be expected during the progressive subsidences...to which by our theory these reefs and islands have been subjected, and are liable" ("The Structure and Distribution of Coral Reefs," page 107: London, 1842).) This admission, I believe, is in no way fatal to the theory, though it is so to certain few passages in my book. In the areas where the large groups of atolls stand, and where likewise a few scattered atolls stand between such groups, I always imagined that there must have been great tracts of land, and that on such large tracts there must have been mountains of immense altitudes. But not, it appears to me, that one is only justified in supposing that groups of islands stood there. There are (as I believe) many considerable islands and groups of islands (Galapagos Islands, Great Britain, Falkland Islands, Marianas, and, I believe, Viti groups), and likewise the majority of single scattered islands, all of which a subsidence between 4,000 and 5,000 feet would entirely submerge or would leave only one or two summits above water, and hence they would produce either groups of nothing but atolls, or of atolls with one or two encircled islands. I am far from wishing to say that the islands of the great oceans have not subsided, or may not continue to subside, any number of feet, but if the average duration (from all causes of destruction) of reefs on the same spot is limited, then after this limit has elapsed the reefs would perish, and if the subsidence continued they would be carried down; and if the group consisted only of atolls, only open ocean would be left; if it consisted partly or wholly of encircled islands, these would be left naked and reefless, but should the area again become favourable for growth of reefs, new barrier-reefs might be formed round them. As an illustration of this notion of a certain average duration of reefs on the same spot, compared with the average rate of subsidence, we may take the case of Tahiti, an island of 7,000 feet high. Now here the present barrier-reefs would never be continued upwards into an atoll, although, should the subsidence continue at a period long after the death of the present reefs, new ones might be formed high up round its sides and ultimately over it. The case resolves itself into: what is the ordinary height of groups of islands, of the size of existing groups of atolls (excepting as many of the highest islands as there now ordinarily occur encircling barrier-reefs in the existing groups of atolls)? and likewise what is the height of the single scattered islands standing between such groups of islands? Subsidence sufficient to bury all these islands (with the exception of as many of the highest as there are encircled islands in the present groups of atolls) my theory absolutely requires, but no more. To say what amount of subsidence would be required for this end, one ought to know the height of all existing islands, both single ones and those in groups, on the face of the globe--and, indeed, of half a dozen worlds like ours. The reefs may be of much greater [thickness] than that just sufficient on an average to bury groups of islands; and the probability of the thickness being greater seems to resolve itself into the average rate of subsidence allowing upward growth, and average duration of reefs on the same spot. Who will say what this rate and what this duration is? but till both are known, we cannot, I think, tell whether we ought to look for upraised coral formations (putting on one side denudation) above the unknown limit, say between 3,000 and 5,000 feet, necessary to submerge groups of common islands. How wretchedly involved do these speculations become. LETTER 534. TO E. VON MOJSISOVICS. Down, January 29th, 1879. I thank you cordially for the continuation of your fine work on the Tyrolese Dolomites (534/1. "Dolomitriffe Sudtirols und Venetiens": Wien, 1878.), with its striking engravings and the maps, which are quite wonderful from the amount of labour which they exhibit, and its extreme difficulty. I well remember more than forty years ago examining a section of Silurian limestone containing many corals, and thinking to myself that it would be for ever impossible to discover whether the ancient corals had formed atolls or barrier reefs; so you may well believe that your work will interest me greatly as soon as I can find time to read it. I am much obliged for your photograph, and from its appearance rejoice to see that much more good work may be expected from you. I enclose my own photograph, in case you should like to possess a copy. LETTER 535. TO A. AGASSIZ. (535/1. Part of this letter is published in "Life and Letters," III., pages 183, 184.) Down, May 5th, 1881. It was very good of you to write to me from Tortugas, as I always feel much interested in hearing what you are about, and in reading your many discoveries. It is a surprising fact that the peninsula of Florida should have remained at the same level for the immense period requisite for the accumulation of so vast a pile of debris. (535/2. Alexander Agassiz published a paper on "The Tortugas and Florida Reefs" in the "Mem. Amer. Acad. Arts and Sci." XI., page 107, 1885. See also his "Three Cruises of the 'Blake,'" Volume I., 1888.) You will have seen Mr. Murray's views on the formation of atolls and barrier reefs. (535/3. "On the Structure and Origin of Coral Reefs and Islands," "Proc. R. Soc. Edin." Volume X., page 505, 1880. Prof. Bonney has given a summary of Sir John Murray's views in Appendix II. of the third edition of Darwin's "Coral Reefs," 1889.) Before publishing my book, I thought long over the same view, but only as far as ordinary marine organisms are concerned, for at that time little was known of the multitude of minute oceanic organisms. I rejected this view, as from the few dredgings made in the 'Beagle' in the S. Temperate regions, I concluded that shells, the smaller corals, etc., etc., decayed and were dissolved when not protected by the deposition of sediment; and sediment could not accumulate in the open ocean. Certainly shells, etc., were in several cases completely rotten, and crumbled into mud between my fingers; but you will know well whether this is in any degree common. I have expressly said that a bank at the proper depth would give rise to an atoll, which could not be distinguished from one formed during subsidence. I can, however, hardly believe, in the former presence of as many banks (there having been no subsidence) as there are atolls in the great oceans, within a reasonable depth, on which minute oceanic organisms could have accumulated to the thickness of many hundred feet. I think that it has been shown that the oscillations from great waves extend down to a considerable depth, and if so the oscillating water would tend to lift up (according to an old doctrine propounded by Playfair) minute particles lying at the bottom, and allow them to be slowly drifted away from the submarine bank by the slightest current. Lastly, I cannot understand Mr. Murray, who admits that small calcareous organisms are dissolved by the carbonic acid in the water at great depths, and that coral reefs, etc., etc., are likewise dissolved near the surface, but that this does not occur at intermediate depths, where he believes that the minute oceanic calcareous organisms accumulate until the bank reaches within the reef-building depth. But I suppose that I must have misunderstood him. Pray forgive me for troubling you at such a length, but it has occurred to me that you might be disposed to give, after your wide experience, your judgment. If I am wrong, the sooner I am knocked on the head and annihilated so much the better. It still seems to me a marvellous thing that there should not have been much and long-continued subsidence in the beds of the great oceans. I wish that some doubly rich millionaire would take it into his head to have borings made in some of the Pacific and Indian atolls, and bring home cores for slicing from a depth of 500 or 600 feet. (535/4. In 1891 a Committee of the British Association was formed for the investigation of an atoll by means of boring. The Royal Society took up the scheme, and an expedition was sent to Funafuti, with Prof. Sollas as leader. Another expedition left Sydney in 1897 under the direction of Prof. Edgeworth David, and a deeper boring was made. The Reports will be published in the "Philosophical Transactions," and will contain Prof. David's notes upon the boring and the island generally, Dr. Hinde's description of the microscopic structure of the cores and other examinations of them, carried on at the Royal College of Science, South Kensington. The boring reached a depth of 1114 feet; the cores were found to consist entirely of reef-forming corals in situ and in fragments, with foraminifera and calcareous algae; at the bottom there were no traces of any other kind of rock. It seems, therefore, to us, that unless it can be proved that reef-building corals began their work at depths of at least 180 fathoms--far below that hitherto assigned--the result gives the strongest support to Darwin's theory of subsidence; the test which Darwin wished to be applied has been fairly tried, and the verdict is entirely in his favour.) 2.IX.V. CLEAVAGE AND FOLIATION, 1846-1856. LETTER 536. TO D. SHARPE. (536/1. The following eight letters were written at a time when the subjects of cleavage and foliation were already occupying the minds of several geologists, including Sharpe, Sorby, Rogers, Haughton, Phillips, and Tyndall. The paper by Sharpe referred to was published in 1847 ("Quart. Journ. Geol. Soc." Volume III.), and his ideas were amplified in two later papers (ibid., Volume V., 1849, and "Phil. Trans." 1852). Darwin's own views, based on his observations during the "Beagle" expedition, had appeared in Chapter XIII. of "South America" (1846) and in the "Manual of Scientific Enquiry" (1849), but are perhaps nowhere so clearly expressed as in this correspondence. His most important contribution to the question was in establishing the fact that foliation is often a part of the same process as cleavage, and is in nowise necessarily connected with planes of stratification. Herein he was opposed to Lyell and the other geologists of the day, but time has made good his position. The postscript to Letter 542 is especially interesting. We are indebted to Mr. Harker, of St. John's College, for this note.) Down, August 23rd [1846?]. I must just send one line to thank you for your note, and to say how heartily glad I am that you stick to the cleavage and foliation question. Nothing will ever convince me that it is not a noble subject of investigation, which will lead some day to great views. I think it quite extraordinary how little the subject seems to interest British geologists. You will, I think live to see the importance of your paper recognised. (536/2. Probably the paper "On Slaty Cleavage." "Quart. Journ. Geol. Soc." Volume III., page 74, 1847.) I had always thought that Studer was one of the few geologists who had taken a correct and enlarged view on the subject. LETTER 537. TO D. SHARPE. Down [November 1846]. I have been much interested with your letter, and am delighted that you have thought my few remarks worth attention. My observations on foliation are more deserving confidence than those on cleavage; for during my first year in clay-slate countries, I was quite unaware of there being any marked difference between cleavage and stratification; I well remember my astonishment at coming to the conclusion that they were totally different actions, and my delight at subsequently reading Sedgwick's views (537/1. "Remarks on the Structure of Large Mineral Masses, and especially on the Chemical Changes produced in the Aggregation of Stratified Rocks during different periods after their Deposition." "Trans. Geol. Soc." Volume III., page 461, 1835. In the section of this paper dealing with cleavage (page 469) Prof. Sedgwick lays stress on the fact that "the cleavage is in no instance parallel to the true beds."); hence at that time I was only just getting out of a mist with respect to cleavage-laminae dipping inwards on mountain flanks. I have certainly often observed it--so often that I thought myself justified in propounding it as usual. I might perhaps have been in some degree prejudiced by Von Buch's remarks, for which in those days I had a somewhat greater deference than I now have. The Mount at M. Video (page 146 of my book (537/2. "Geol. Obs. S. America." page 146. The mount is described as consisting of hornblendic slate; "the laminae of the slate on the north and south side near the summit dip inwards.")) is certainly an instance of the cleavage-laminae of a hornblendic schist dipping inwards on both sides, for I examined this hill carefully with compass in hand and notebook. I entirely admit, however, that a conclusion drawn from striking a rough balance in one's mind is worth nothing compared with the evidence drawn from one continuous line of section. I read Studer's paper carefully, and drew the conclusion stated from it; but I may very likely be in an error. I only state that I have frequently seen cleavage-laminae dipping inwards on mountain sides; that I cannot give up, but I daresay a general extension of the rule (as might justly be inferred from the manner of my statement) would be quite erroneous. Von Buch's statement is in his "Travels in Norway" (537/3. "Travels through Norway and Lapland during the years 1806-8": London, 1813.); I have unfortunately lost the reference, and it is a high crime, I confess, even to refer to an opinion without a precise reference. If you never read these travels they might be worth skimming, chiefly as an amusement; and if you like and will send me a line by the general post of Monday or Tuesday, I will either send it up with Hopkins on Wednesday, or bring it myself to the Geological Society. I am very glad you are going to read Hopkins (537/4. "Researches in Physical Geology," by W. Hopkins. "Phil. Trans. R. Soc." 1839, page 381; ibid, 1842, page 43, etc.); his views appear to me eminently worth well comprehending; false views and language appear to me to be almost universally held by geologists on the formation of fissures, dikes and mountain chains. If you would have the patience, I should be glad if you would read in my "Volcanic Islands" from page 65, or even pages 54 to 72--viz., on the lamination of volcanic rocks; I may add that I sent the series of specimens there described to Professor Forbes of Edinburgh, and he thought they bore out my views. There is a short extract from Prof. Rogers (537/5. "On Cleavage of Slate-strata." "Edinburgh New Phil. Journ." Volume XLI., page 422, 1846.) in the last "Edinburgh New Phil. Journal," well worth your attention, on the cleavage of the Appalachian chain, and which seems far more uniform in the direction of dip than in any case which I have met with; the Rogers doctrine of the ridge being thrown up by great waves I believe is monstrous; but the manner in which the ridges have been thrown over (as if by a lateral force acting on one side on a higher level than on the other) is very curious, and he now states that the cleavage is parallel to the axis-planes of these thrown-over ridges. Your case of the limestone beds to my mind is the greatest difficulty on any mechanical doctrine; though I did not expect ever to find actual displacement, as seems to be proved by your shell evidence. I am extremely glad you have taken up this most interesting subject in such a philosophical spirit; I have no doubt you will do much in it; Sedgwick let a fine opportunity slip away. I hope you will get out another section like that in your letter; these are the real things wanted. LETTER 538. TO D. SHARPE. Down, [January 1847]. I am very much obliged for the MS., which I return. I do not quite understand from your note whether you have struck out all on this point in your paper: I much hope not; if you have, allow me to urge on you to append a note, briefly stating the facts, and that you omitted them in your paper from the observations not being finished. I am strongly tempted to suspect that the cleavage planes will be proved by you to have slided a little over each other, and to have been planes of incipient tearing, to use Forbes' expression in ice; it will in that case be beautifully analogical with my laminated lavas, and these in composition are intimately connected with the metamorphic schists. The beds without cleavage between those with cleavage do not weigh quite so heavily on me as on you. You remember, of course, Sedgwick's facts of limestone, and mine of sandstone, breaking in the line of cleavage, transversely to the planes of deposition. If you look at cleavage as I do, as the result of chemical action or crystalline forces, super-induced in certain places by their mechanical state of tension, then it is not surprising that some rocks should yield more or less readily to the crystalline forces. I think I shall write to Prof. Forbes (538/1. Prof. D. Forbes.) of Edinburgh, with whom I corresponded on my laminated volcanic rocks, to call his early attention to your paper. LETTER 539. TO D. SHARPE. Down, October 16th [1851]. I am very much obliged to you for telling me the results of your foliaceous tour, and I am glad you are drawing up an account for the Royal Society. (539/1. "On the Arrangement of the Foliation and Cleavage of the Rocks of the North of Scotland." "Phil. Trans. R. Soc." 1852, page 445, with Plates XXIII. and XXIV.) I hope you will have a good illustration or map of the waving line of junction of the slate and schist with uniformly directed cleavage and foliation. It strikes me as crucial. I remember longing for an opportunity to observe this point. All that I say is that when slate and the metamorphic schists occur in the same neighbourhood, the cleavage and foliation are uniform: of this I have seen many cases, but I have never observed slate overlying mica-slate. I have, however, observed many cases of glossy clay-slate included within mica-schist and gneiss. All your other observations on the order, etc., seem very interesting. From conversations with Lyell, etc., I recommend you to describe in a little detail the nature of the metamorphic schists; especially whether there are quasi-substrata of different varieties of mica-slate or gneiss, etc.; and whether you traced such quasi beds into the cleavage slate. I have not the least doubt of such facts occurring, from what I have seen (and described at M. Video) of portions of fine chloritic schists being entangled in the midst of a gneiss district. Have you had any opportunity of tracing a bed of marble? This, I think, from reasons given at page 166 of my "S. America," would be very interesting. (539/2. "I have never had an opportunity of tracing, for any distance, along the line both of strike and dip, the so-called beds in the metamorphic schists, but I strongly suspect that they would not be found to extend, with the same character, very far in the line either of their dip or strike. Hence I am led to believe that most of the so-called beds are of the nature of complex folia, and have not been separately deposited. Of course, this view cannot be extended to THICK masses included in the metamorphic series, which are of totally different composition from the adjoining schists, and which are far-extended, as is sometimes the case with quartz and marble; these must generally be of the nature of true strata" ("Geological Observations," page 166).) A suspicion has sometimes occurred to me (I remember more especially when tracing the clay-slate at the Cape of Good Hope turning into true gneiss) that possibly all the metamorphic schists necessarily once existed as clay-slate, and that the foliation did not arise or take its direction in the metamorphic schists, but resulted simply from the pre-existing cleavage. The so-called beds in the metamorphic schists, so unlike common cleavage laminae, seems the best, or at least one argument against such a suspicion. Yet I think it is a point deserving your notice. Have you thought at all over Rogers' Law, as he reiterates it, of cleavage being parallel to his axes-planes of elevation? If you know beforehand, will you tell me when your paper is read, for the chance of my being able to attend? I very seldom leave home, as I find perfect quietude suits my health best. (PLATE: CHARLES DARWIN, Cir. 1854. Maull & Fox, photo. Walker & Cockerell, ph. sc.) LETTER 540. TO C. LYELL. Down, January 10th, 1855. I received your letter yesterday, but was unable to answer it, as I had to go out at once on business of importance. I am very glad that you are reconsidering the subject of foliation; I have just read over what I have written on the subject, and admire it very much, and abide by it all. (540/1. "Geological Observations on South America," Chapter VI., 1846.) You will not readily believe how closely I attended to the subject, and in how many and wide areas I verified my remarks. I see I have put pretty strongly the mechanical view of origin; but I might even then, but was afraid, have put my belief stronger. Unfortunately I have not D. Sharpe's paper here to look over, but I think his chief points [are] (1) the foliation forming great symmetrical curves, and (2) the proof from effects of form of shell (540/2. This refers to the distortion of shells in cleaved rocks.) of the mechanical action in cleaved rocks. The great curvature would be, I think, a grand discovery of Sharpe's, but I confess there is some want of minuteness in the statement of Sharpe which makes me wish to see his facts confirmed. That the foliation and cleavage are parts of curves I am quite prepared, from what I have seen, to believe; but the simplicity and grandeur of Sharpe's curves rather stagger me. I feel deeply convinced that when (and I and Sharpe have seen several most striking and obvious examples) great neighbouring or alternating regions of true metamorphic schists and clay-slate have their foliations and cleavage parallel, there is no way of escaping the conclusion, that the layers of pure quartz, feldspar, mica, chlorite, etc., etc., are due not to original deposition, but to segregation; and this is I consider the point which I have established. This is very odd, but I suspect that great metamorphic areas are generally derived from the metamorphosis of clay-slate, and not from alternating layers of ordinary sedimentary matter. I think you have exactly put the chief difficulty in its strongest light--viz. what would be the result of pure or nearly pure layers of very different mineralogical composition being metamorphosed? I believe even such might be converted into an ordinary varying mass of metamorphic schists. I am certain of the correctness of my account of patches of chlorite schists enclosed in other schist, and of enormous quartzose veins of segregation being absolutely continuous and contemporaneous with the folia of quartz, and such, I think, might be the result of the folia crossing a true stratum of quartz. I think my description of the wonderful and beautiful laminated volcanic rocks at Ascension would be worth your looking at. (540/3. "Geological Observations on S. America," pages 166, 167; also "Geological Observations on the Volcanic Islands," Chapter III. (Ascension), 1844.) LETTER 541. TO C. LYELL. Down, January 14th [1855]. We were yesterday and the day before house-hunting, so I could not answer your letter. I hope we have succeeded in a house, after infinite trouble, but am not sure, in York Place, Baker Street. I do not doubt that I either read or heard from Sharpe about the Grampians; otherwise from my own old suspicion I should not have inserted the passage in the manual. The laminated rocks at Ascension are described at page 54. (541/1. "Volcanic Islands," page 54. "Singular laminated beds alternating with and passing into obsidian.") As far as my experience has gone, I should speak only of clay-slate being associated with mica-slate, for when near the metamorphic schists I have found stratification so gone that I should not dare to speak of them as overlying them. With respect to the difficulty of beds of quartz and marble, this has for years startled me, and I have longed (since I have felt its force) to have some opportunity of testing this point, for without you are sure that the beds of quartz dip, as well as strike, parallel to the foliation, the case is only just like true strata of sandstone included in clay-slate and striking parallel to the cleavage of the clay-slate, but of course with different dip (excepting in those rare cases when cleavage and stratification are parallel). Having this difficulty before my eyes, I was much struck with MacCulloch's statement (page 166 of my "S. America") about marble in the metamorphic series not forming true strata. (FIGURE 6.) Your expectation of the metamorphic schists sending veins into neighbouring rocks is quite new to me; but I much doubt whether you have any right to assume fluidity from almost any amount of molecular change. I have seen in fine volcanic sandstone clear evidence of all the calcareous matter travelling at least 4 1/2 feet in distance to concretions on either hand (page 113 of "S. America") (541/2. "Some of these concretions (flattened spherical concretions composed of hard calcareous sandstone, containing a few shells, occurring in a bed of sandstone) were 4 feet in diameter, and in a horizontal line 9 feet apart, showing that the calcareous matter must have been drawn to the centres of attraction from a distance of four feet and a half on both sides" ("Geological Observations on S. America," page 113).) I have not examined carefully, from not soon enough seeing all the difficulties; but I believe, from what I have seen, that the folia in the metamorphic schists (I do not here refer to the so-called beds) are not of great length, but thin out, and are succeeded by others; and the notion I have of the molecular movements is shown in the indistinct sketch herewith sent [Figure 6]. The quartz of the strata might here move into the position of the folia without much more movement of molecules than in the formation of concretions. I further suspect in such cases as this, when there is a great original abundance of quartz, that great branching contemporaneous veins of segregation (as sometimes called) of quartz would be formed. I can only thus understand the relation which exists between the distorted foliation (not appearing due to injection) and the presence of such great veins. I believe some gneiss, as the gneiss-granite of Humboldt, has been as fluid as granite, but I do not believe that this is usually the case, from the frequent alternations of glossy clay and chlorite slates, which we cannot suppose to have been melted. I am far from wishing to doubt that true sedimentary strata have been converted into metamorphic schists: all I can say is, that in the three or four great regions, where I could ascertain the relations of the metamorphic schists to the neighbouring cleaved rocks, it was impossible (as it appeared to me) to admit that the foliation was due to aqueous deposition. Now that you intend agitating the subject, it will soon be cleared up. LETTER 542. TO C. LYELL. 27, York Place, Baker Street [1855]. I have received your letter from Down, and I have been studying my S. American book. I ought to have stated [it] more clearly, but undoubtedly in W. Tierra del Fuego, where clay-slate passes by alternation into a grand district of mica-schist, and in the Chonos Islands and La Plata, where glossy slates occur within the metamorphic schists, the foliation is parallel to the cleavage--i.e. parallel in strike and dip; but here comes, I am sorry and ashamed to say, a great hiatus in my reasoning. I have assumed that the cleavage in these neighbouring or intercalated beds was (as in more distant parts) distinct from stratification. If you choose to say that here the cleavage was or might be parallel to true bedding, I cannot gainsay it, but can only appeal to apparent similarity to the great areas of uniformity of strike and high angle--all certainly unlike, as far as my experience goes, to true stratification. I have long known how easily I overlook flaws in my own reasoning, and this is a flagrant case. I have been amused to find, for I had quite forgotten, how distinctly I give a suspicion (top of page 155) to the idea, before Sharpe, of cleavage (not foliation) being due to the laminae forming parts of great curves. (542/1. "I suspect that the varying and opposite dips (of the cleavage-planes) may possibly be accounted for by the cleavage-laminae...being parts of large abrupt curves, with their summits cut off and worn down" ("Geological Observations on S. America," page 155). I well remember the fine section at the end of a region where the cleavage (certainly cleavage) had been most uniform in strike and most variable in dip. I made with really great care (and in MS. in detail) observations on a case which I believe is new, and bears on your view of metamorphosis (page 149, at bottom). (Ibid., page 149.) (FIGURE 7.) In a clay-slate porphyry region, where certain thin sedimentary layers of tuff had by self-attraction shortened themselves into little curling pieces, and then again into crystals of feldspar of large size, and which consequently were all strictly parallel, the series was perfect and beautiful. Apparently also the rounded grains of quartz had in other parts aggregated themselves into crystalline nodules of quartz. [Figure 7.] I have not been able to get Sorby yet, but shall not probably have anything to write on it. I am delighted you have taken up the subject, even if I am utterly floored. P.S.--I have a presentiment it will turn out that when clay-slate has been metamorphosed the foliation in the resultant schist has been due generally (if not, as I think, always) to the cleavage, and this to a certain degree will "save my bacon" (please look at my saving clause, page 167) (542/2. "As in some cases it appears that where a fissile rock has been exposed to partial metamorphic action (for instance, from the irruption of granite) the foliation has supervened on the already existing cleavage-planes; so, perhaps in some instances, the foliation of a rock may have been determined by the original planes of deposition or of oblique current laminae. I have, however, myself never seen such a case, and I must maintain that in most extensive metamorphic areas the foliation is the extreme result of that process, of which cleavage is the first effect" (Ibid., page 167).), but [with] other rocks than that, stratification has been the ruling agent, the strike, but not the dip, being in such cases parallel to any adjoining clay-slate. If this be so, pre-existing planes of division, we must suppose on my view of the cause, determining the lines of crystallisation and segregation, and not planes of division produced for the first time during the act of crystallisation, as in volcanic rocks. If this should ever be proved, I shall not look back with utter shame at my work. LETTER 543. TO J.D. HOOKER. Down, September 8th [1856]. I got your letter of the 1st this morning, and a real good man you have been to write. Of all the things I ever heard, Mrs. Hooker's pedestrian feats beat them. My brother is quite right in his comparison of "as strong as a woman," as a type of strength. Your letter, after what you have seen in the Himalayas, etc., gives me a wonderful idea of the beauty of the Alps. How I wish I was one-half or one-quarter as strong as Mrs. Hooker: but that is a vain hope. You must have had some very interesting work with glaciers, etc. When will the glacier structure and motion ever be settled! When reading Tyndall's paper it seemed to me that movement in the particles must come into play in his own doctrine of pressure; for he expressly states that if there be pressure on all sides, there is no lamination. I suppose I cannot have understood him, for I should have inferred from this that there must have been movement parallel to planes of pressure. (543/1. Prof. Tyndall had published papers "On Glaciers," and "On some Physical Properties of Ice" ("Proc. R. Inst." 1854-58) before the date of this letter. In 1856 he wrote a paper entitled "Observations on 'The Theory of the Origin of Slaty Cleavage,' by H.C. Sorby." "Phil. Mag." XII., 1856, page 129.) Sorby read a paper to the Brit. Assoc., and he comes to the conclusion that gneiss, etc., may be metamorphosed cleavage or strata; and I think he admits much chemical segregation along the planes of division. (543/2. "On the Microscopical Structure of Mica-schist:" "Brit. Ass. Rep." 1856, page 78. See also Letters 540-542.) I quite subscribe to this view, and should have been sorry to have been so utterly wrong, as I should have been if foliation was identical with stratification. I have been nowhere and seen no one, and really have no news of any kind to tell you. I have been working away as usual, floating plants in salt water inter alia, and confound them, they all sink pretty soon, but at very different rates. Working hard at pigeons, etc., etc. By the way, I have been astonished at the differences in the skeletons of domestic rabbits. I showed some of the points to Waterhouse, and asked him whether he could pretend that they were not as great as between species, and he answered, "They are a great deal more." How very odd that no zoologist should ever have thought it worth while to look to the real structure of varieties... 2.IX.VI. AGE OF THE WORLD, 1868-1877. LETTER 544. TO J. CROLL. Down, September 19th, 1868. I hope that you will allow me to thank you for sending me your papers in the "Phil. Magazine." (544/1. Croll published several papers in the "Philosophical Magazine" between 1864 and the date of this letter (1868).) I have never, I think, in my life been so deeply interested by any geological discussion. I now first begin to see what a million means, and I feel quite ashamed of myself at the silly way in which I have spoken of millions of years. I was formerly a great believer in the power of the sea in denudation, and this was perhaps natural, as most of my geological work was done near sea-coasts and on islands. But it is a consolation to me to reflect that as soon as I read Mr. Whitaker's paper (544/2. "On Subaerial Denudation," and "On Cliffs and Escarpments of the Chalk and Lower Tertiary Beds," "Geol. Mag." Volume IV., page 447, 1867.) on the escarpments of England, and Ramsay (544/3. "Quart. Journ. Geol. Soc." Volume XVIII., page 185, 1862. "On the Glacial Origin of certain Lakes in Switzerland, the Black Forest, Great Britain, Sweden, North America, and elsewhere.') and Jukes' papers (544/4. "Quart. Journ. Geol. Soc." Volume XVIII., page 378, 1862. "On the Mode of Formation of some River-Valleys in the South of Ireland."), I gave up in my own mind the case; but I never fully realised the truth until reading your papers just received. How often I have speculated in vain on the origin of the valleys in the chalk platform round this place, but now all is clear. I thank you cordially for having cleared so much mist from before my eyes. LETTER 545. TO T. MELLARD READE. Down, February 9th, 1877. I am much obliged for your kind note, and the present of your essay. I have read it with great interest, and the results are certainly most surprising. (545/1. Presidential Address delivered by T. Mellard Reade before the Liverpool Geological Society ("Proc. Liverpool Geol. Soc." Volume III., pt. iii., page 211, 1877). See also "Examination of a Calculation of the Age of the Earth, based upon the hypothesis of the Permanence of Oceans and Continents." "Geol. Mag." Volume X., page 309, 1883.) It appears to me almost monstrous that Professor Tait should say that the duration of the world has not exceeded ten million years. (545/2. "Lecture on Some Recent Advances in Physical Science," by P.G. Tait, London, 1876.) The argument which seems the most weighty in favour of the belief that no great number of millions of years have elapsed since the world was inhabited by living creatures is the rate at which the temperature of the crust increases, and I wish that I could see this argument answered. LETTER 546. TO J. CROLL. Down, August 9th, 1877. I am much obliged for your essay, which I have read with the greatest interest. With respect to the geological part, I have long wished to see the evidence collected on the time required for denudation, and you have done it admirably. (546/1. In a paper "On the Tidal Retardation Argument for the Age of the Earth" ("Brit. Assoc. Report," 1876, page 88), Croll reverts to the influence of subaerial denudation in altering the form of the earth as an objection to the argument from tidal retardation. He had previously dealt with this subject in "Climate and Time," Chapter XX., London, 1875.) I wish some one would in a like spirit compare the thickness of sedimentary rocks with the quickest estimated rate of deposition by a large river, and other such evidence. Your main argument with respect to the sun seems to me very striking. My son George desires me to thank you for his copy, and to say how much he has been interested by it. 2.IX.VII. GEOLOGICAL ACTION OF EARTHWORMS, 1880-1882. "My whole soul is absorbed with worms just at present." (From a letter to Sir W. Thistleton-Dyer, November 26th, 1880.) LETTER 547. TO T.H. FARRER (Lord Farrer). (547/1. The five following letters, written shortly before and after the publication of "The Formation of Vegetable Mould through the Action of Worms," 1881, deal with questions connected with Mr. Darwin's work on the habits and geological action of earthworms.) Down, October 20th, 1880. What a man you are to do thoroughly whatever you undertake to do! The supply of specimens has been magnificent, and I have worked at them for a day and a half. I find a very few well-rounded grains of brick in the castings from over the gravel walk, and plenty over the hole in the field, and over the Roman floor. (547/2. See "The Formation of Vegetable Mould," 1881, pages 178 et seq. The Roman remains formed part of a villa discovered at Abinger, Surrey. Excavations were carried out, under Lord Farrer's direction, in a field adjoining the ground in which the Roman villa was first found, and extended observations were made by Lord Farrer, which led Mr. Darwin to conclude that a large part of the fine vegetable mould covering the floor of the villa had been brought up from below by worms.) You have done me the greatest possible service by making me more cautious than I should otherwise have been--viz., by sending me the rubbish from the road itself; in this rubbish I find very many particles, rounded (I suppose) by having been crushed, angles knocked off, and somewhat rolled about. But not a few of the particles may have passed through the bodies of worms during the years since the road was laid down. I still think that the fragments are ground in the gizzards of worms, which always contain bits of stone; but I must try and get more evidence. I have to-day started a pot with worms in very fine soil, with sharp fragments of hard tiles laid on the surface, and hope to see in the course of time whether any of those become rounded. I do not think that more specimens from Abinger would aid me... LETTER 548. TO G.J. ROMANES. Down, March 7th. I was quite mistaken about the "Gardeners' Chronicle;" in my index there are only the few enclosed and quite insignificant references having any relation to the minds of animals. When I returned to my work, I found that I had nearly completed my statement of facts about worms plugging up their burrows with leaves (548/1. Chapter II., of "The Formation of Vegetable Mould through the Action of Worms," 1881, contains a discussion on the intelligence shown by worms in the manner of plugging up their burrows with leaves (pages 78 et seq.).), etc., etc., so I waited until I had naturally to draw up a few concluding remarks. I hope that it will not bore you to read the few accompanying pages, and in the middle you will find a few sentences with a sort of definition of, or rather discussion on, intelligence. I am altogether dissatisfied with it. I tried to observe what passed in my own mind when I did the work of a worm. If I come across a professed metaphysician, I will ask him to give me a more technical definition, with a few big words about the abstract, the concrete, the absolute, and the infinite; but seriously, I should be grateful for any suggestions, for it will hardly do to assume that every fool knows what "intelligent" means. (548/2. "Mr. Romanes, who has specially studied the minds of animals, believes that we can safely infer intelligence only when we see an individual profiting by its own experience...Now, if worms try to drag objects into their burrows, first in one way and then in another, until they at last succeed, they profit, at least in each particular instance, by experience" ("The Formation of Vegetable Mould," 1881, page 95).) You will understand that the MS. is only the first rough copy, and will need much correction. Please return it, for I have no other copy--only a few memoranda. When I think how it has bothered me to know what I mean by "intelligent," I am sorry for you in your great work on the minds of animals. I daresay that I shall have to alter wholly the MS. LETTER 549. TO FRANCIS GALTON. Down, March 8th [1881]. Very many thanks for your note. I have been observing the [worm] tracks on my walks for several months, and they occur (or can be seen) only after heavy rain. As I know that worms which are going to die (generally from the parasitic larva of a fly) always come out of their burrows, I have looked out during these months, and have usually found in the morning only from one to three or four along the whole length of my walks. On the other hand, I remember having in former years seen scores or hundreds of dead worms after heavy rain. (549/1. "After heavy rain succeeding dry weather, an astonishing number of dead worms may sometimes be seen lying on the ground. Mr. Galton informs me that on one occasion (March, 1881), the dead worms averaged one for every two-and-a-half paces in length on a walk in Hyde Park, four paces in width" (loc. cit., page 14).) I cannot possibly believe that worms are drowned in the course of even three or four days' immersion; and I am inclined to conclude that the death of sickly (probably with parasites) worms is thus hastened. I will add a few words to what I have said about these tracks. Occasionally worms suffer from epidemics (of what nature I know not) and die by the million on the surface of the ground. Your ruby paper answers capitally, but I suspect that it is only for dimming the light, and I know not how to illuminate worms by the same intensity of light, and yet of a colour which permits the actinic rays to pass. I have tried drawing triangles of damp paper through a small cylindrical hole, as you suggested, and I can discover no source of error. (549/2. Triangles of paper were used in experiments to test the intelligence of worms (loc. cit., page 83).) Nevertheless, I am becoming more doubtful about the intelligence of worms. The worst job is that they will do their work in a slovenly manner when kept in pots (549/3. Loc. cit., page 75.), and I am beyond measure perplexed to judge how far such observations are trustworthy. LETTER 550. TO E. RAY LANKESTER. (550/1. Mr. Lankester had written October 11th, 1881, to thank Mr. Darwin for the present of the Earthworm book. He asks whether Darwin knows of "any experiments on the influence of sea-water on earthworms. I have assumed that it is fatal to them. But there is a littoral species (Pontodrilus of Perrier) found at Marseilles." Lankester adds, "It is a great pleasure and source of pride to me to see my drawing of the earthworm's alimentary canal figuring in your pages." Down, October 13th [1881]. I have been much pleased and interested by your note. I never actually tried sea-water, but I was very fond of angling when a boy, and as I could not bear to see the worms wriggling on the hook, I dipped them always first in salt water, and this killed them very quickly. I remember, though not very distinctly, seeing several earthworms dead on the beach close to where a little brook entered, and I assumed that they had been brought down by the brook, killed by the sea-water, and cast on shore. With your skill and great knowledge, I have no doubt that you will make out much new about the anatomy of worms, whenever you take up the subject again. LETTER 551. TO J.H. GILBERT. Down, January, 12th, 1882. I have been much interested by your letter, for which I thank you heartily. There was not the least cause for you to apologise for not having written sooner, for I attributed it to the right cause, i.e. your hands being full of work. Your statement about the quantity of nitrogen in the collected castings is most curious, and much exceeds what I should have expected. In lately reading one of your and Mr. Lawes' great papers in the "Philosophical Transactions" (551/1. The first Report on "Agricultural, Botanical, and Chemical Results of Experiments on the Mixed Herbage of Permanent Grassland, conducted for many years in succession on the same land," was published in the "Philosophical Transactions of the Royal Society" in 1880, the second paper appeared in the "Phil. Trans." for 1882, and the third in the "Phil. Trans." of 1900, Volume 192, page 139.) (the value and importance of which cannot, in my opinion, be exaggerated) I was struck with the similarity of your soil with that near here; and anything observed here would apply to your land. Unfortunately I have never made deep sections in this neighbourhood, so as to see how deep the worms burrow, except in one spot, and here there had been left on the surface of the chalk a little very fine ferruginous sand, probably of Tertiary age; into this the worms had burrowed to a depth of 55 and 61 inches. I have never seen here red castings on the surface, but it seems possible (from what I have observed with reddish sand) that much of the red colour of the underlying clay would be discharged in passing through the intestinal canal. Worms usually work near the surface, but I have noticed that at certain seasons pale-coloured earth is brought up from beneath the outlying blackish mould on my lawn; but from what depth I cannot say. That some must be brought up from a depth of four or five or six feet is certain, as the worms retire to this depth during very dry and very cold weather. As worms devour greedily raw flesh and dead worms, they could devour dead larvae, eggs, etc., etc., in the soil, and thus they might locally add to the amount of nitrogen in the soil, though not of course if the whole country is considered. I saw in your paper something about the difference in the amount of nitrogen at different depths in the superficial mould, and here worms may have played a part. I wish that the problem had been before me when observing, as possibly I might have thrown some little light on it, which would have pleased me greatly. 2.IX.VIII. MISCELLANEOUS, 1846-1878. (552/1. The following four letters refer to questions connected with the origin of coal.) LETTER 552. TO J.D. HOOKER. Down, May [1846]. I am delighted that you are in the field, geologising or palaeontologising. I beg you to read the two Rogers' account of the Coal-fields of N. America; in my opinion they are eminently instructive and suggestive. (552/1. "On the Physical Structure of the Appalachian Chain," by W.B. and H.D. Rogers. Boston, 1843. See also "Geology of Pennsylvania," by H.D. Rogers. 4 volumes. London and Philadelphia, 1843.) I can lend you their resume of their own labours, and, indeed, I do not know that their work is yet published in full. L. Horner gives a capital balance of difficulties on the Coal-theory in his last Anniversary Address, which, if you have not read, will, I think, interest you. (552/2. "Quart. Journ. Geol. Soc." Volume II., 1846, page 170.) In a paper just read an author (552/3. "On the Remarkable Fossil Trees lately discovered near St. Helen's." By E.W. Binney. "Phil. Mag." Volume XXIV., page 165, 1844. On page 173 the author writes: "The Stigmaria or Sigillaria, whichever name is to be retained... was a tree that undoubtedly grew in water.") throws out the idea that the Sigillaria was an aquatic plant (552/4. See "Life and Letters," I., pages 356 et seq.)--I suppose a Cycad-Conifer with the habits of the mangrove. From simple geological reasoning I have for some time been led to suspect that the great (and great and difficult it is) problem of the Coal would be solved on the theory of the upright plants having been aquatic. But even on such, I presume improbable notion, there are, as it strikes me, immense difficulties, and none greater than the width of the coal-fields. On what kind of coast or land could the plants have lived? It is a grand problem, and I trust you will grapple with it. I shall like much to have some discussion with you. When will you come here again? I am very sorry to infer from your letter that your sister has been ill. LETTER 553. TO J.D. HOOKER. [June 2nd, 1847.] I received your letter the other day, full of curious facts, almost all new to me, on the coal-question. (553/1. Sir Joseph Hooker deals with the formation of coal in his classical paper "On the Vegetation of the Carboniferous Period, as compared with that of the Present Day." "Mem. Geol. Surv. Great Britain," Volume II., pt. ii., 1848.) I will bring your note to Oxford (553/2. The British Association met at Oxford in 1847.), and then we will talk it over. I feel pretty sure that some of your purely geological difficulties are easily solvable, and I can, I think, throw a very little light on the shell difficulty. Pray put no stress in your mind about the alternate, neatly divided, strata of sandstone and shale, etc. I feel the same sort of interest in the coal question as a man does watching two good players at play, he knowing little or nothing of the game. I confess your last letter (and this you will think very strange) has almost raised Binney's notion (an old, growing hobby-horse of mine) to the dignity of an hypothesis (553/3. Binney suggested that the Coal-plants grew in salt water. (See Letters 102, 552.) Recent investigations have shown that several of the plants of the Coal period possessed certain anatomical peculiarities, which indicate xerophytic characteristics, and lend support to the view that some at least of the plants grew in seashore swamps.), though very far yet below the promotion of being properly called a theory. I will bring the remainder of my species-sketch to Oxford to go over your remarks. I have lately been getting a good many rich facts. I saw the poor old Dean of Manchester (553/4. Dean Herbert.) on Friday, and he received me very kindly. He looked dreadfully ill, and about an hour afterwards died! I am most sincerely sorry for it. LETTER 554. TO J.D. HOOKER. [May 12th, 1847.] I cannot resist thanking you for your most kind note. Pray do not think that I was annoyed by your letter. I perceived that you had been thinking with animation, and accordingly expressed yourself strongly, and so I understood it. Forefend me from a man who weighs every expression with Scotch prudence. I heartily wish you all success in your noble problem, and I shall be very curious to have some talk with you and hear your ultimatum. (554/1. The above paragraph was published in "Life and Letters," I., page 359.) I do really think, after Binney's pamphlet (554/2. "On the Origin of Coal," "Mem. Lit. Phil. Soc." Manchester Volume VIII., page 148, 1848.), it will be worth your while to array your facts and ideas against an aquatic origin of the coal, though I do not know whether you object to freshwater. I am sure I have read somewhere of the cones of Lepidodendron being found round the stump of a tree, or am I confusing something else? How interesting all rooted--better, it seems from what you say, than upright--specimens become. I wish Ehrenberg would undertake a microscopical hunt for infusoria in the underclay and shales; it might reveal something. Would a comparison of the ashes of terrestrial peat and coal give any clue? (554/3. In an article by M. F. Rigaud on "La Formation de la Houille," published in the "Revue Scientifique," Volume II., page 385, 1894, the author lays stress on the absence of certain elements in the ash of coals, which ought to be present, on the assumption that the carbon has been derived from plant tissues. If coal consists of altered vegetable debris, we ought to find a certain amount of alkalies and phosphoric acid in its ash. Had such substances ever been present, it is difficult to understand how they could all have been removed by the solvent action of water. (Rigaud's views are given at greater length in an article on the "Structure and Formation of Coal," "Science Progress," Volume II., pages 355 and 431, 1895.)) Peat ashes are good manure, and coal ashes, except mechanically, I believe are of little use. Does this indicate that the soluble salts have been washed out? i.e., if they are NOT present. I go up to Geological Council to-day--so farewell. (554/4. In a letter to Sir Joseph Hooker, October 6th, 1847, Mr. Darwin, in referring to the origin of Coal, wrote: "...I sometimes think it could not have been formed at all. Old Sir Anthony Carlisle once said to me gravely that he supposed Megatherium and such cattle were just sent down from heaven to see whether the earth would support them, and I suppose the coal was rained down to puzzle mortals. You must work the coal well in India.") LETTER 555. TO J.D. HOOKER. Down, May 22nd, 1860. Lyell tells me that Binney has published in Proceedings of Manchester Society a paper trying to show that Coal plants must have grown in very marine marshes. (555/1. "On the Origin of Coal," by E.W. Binney, "Mem. Lit. Phil. Soc. Manchester," Volume VIII., 1848, page 148. Binney examines the evidence on which dry land has been inferred to exist during the formation of the Coal Measures, and comes to the conclusion that the land was covered by water, confirming Brongniart's opinion that Sigillaria was an aquatic plant. He believes the Sigillaria "grew in water, on the deposits where it is now discovered, and that it is the plant which in a great measure contributed to the formation of our valuable beds of coal." (Loc. cit., page 193.)) Do you remember how savage you were long years ago at my broaching such a conjecture? LETTER 556. TO L. HORNER. Down [1846?]. I am truly pleased at your approval of my book (556/1. "Geological Observations on South America," London, 1846.): it was very kind of you taking the trouble to tell me so. I long hesitated whether I would publish it or not, and now that I have done so at a good cost of trouble, it is indeed highly satisfactory to think that my labour has not been quite thrown away. I entirely acquiesce in your criticism on my calling the Pampean formation "recent" (556/2. "We must, therefore, conclude that the Pampean formation belongs, in the ordinary geological sense of the word, to the Recent Period." ("Geol. Obs." page 101).); Pleistocene would have been far better. I object, however, altogether on principle (whether I have always followed my principle is another question) to designate any epoch after man. It breaks through all principles of classification to take one mammifer as an epoch. And this is presupposing we know something of the introduction of man: how few years ago all beds earlier than the Pleistocene were characterised as being before the monkey epoch. It appears to me that it may often be convenient to speak of an Historical or Human deposit in the same way as we speak of an Elephant bed, but that to apply it to an epoch is unsound. I have expressed myself very ill, and I am not very sure that my notions are very clear on this subject, except that I know that I have often been made wroth (even by Lyell) at the confidence with which people speak of the introduction of man, as if they had seen him walk on the stage, and as if, in a geological chronological sense, it was more important than the entry of any other mammifer. You ask me to do a most puzzling thing, to point out what is newest in my volume, and I found myself incapable of doing almost the same for Lyell. My mind goes from point to point without deciding: what has interested oneself or given most trouble is, perhaps quite falsely, thought newest. The elevation of the land is perhaps more carefully treated than any other subject, but it cannot, of course, be called new. I have made out a sort of index, which will not take you a couple of minutes to skim over, and then you will perhaps judge what seems newest. The summary at the end of the book would also serve same purpose. I do not know where E. de B. [Elie de Beaumont] has lately put forth on the recent elevation of the Cordillera. He "rapported" favourably on d'Orbigny, who in late times fires off a most Royal salute; every volcano bursting forth in the Andes at the same time with their elevation, the debacle thus caused depositing all the Pampean mud and all the Patagonian shingle! Is not this making Geology nice and simple for beginners? We have been very sorry to hear of Bunbury's severe illness; I believe the measles are often dangerous to grown-up people. I am very glad that your last account was so much better. I am astonished that you should have had the courage to go right through my book. It is quite obvious that most geologists find it far easier to write than to read a book. Chapter I. and II.--Elevation of the land: equability on E. coast as shown by terraces, page 19; length on W. coast, page 53; height at Valparaiso, page 32; number of periods of rest at Coquimbo, page 49; elevation within Human period near Lima greater than elsewhere observed; the discussion (page 41) on non-horizontality of terraces perhaps one of newest features--on formation of terraces rather newish. Chapter III., page 65.--Argument of horizontal elevation of Cordillera I believe new. I think the connection (page 54) between earthquake [shocks] and insensible rising important. Chapter IV.--The strangeness of the (Eocene) mammifers, co-existing with recent shells. Chapter V.--Curious pumiceous infusorial mudstone (page 118) of Patagonia; climate of old Tertiary period, page 134. The subject which has been most fertile in my mind is the discussion from page 135 to end of chapter on the accumulation of fossiliferous deposits. (556/3. The last section of Chapter V. treats of "the Absence of extensive modern Conchiferous Deposits in South America; and on the contemporaneousness of the older Tertiary Deposits at distant points being due to contemporaneous movements of subsidence." Darwin expresses the view that "the earth's surface oscillates up and down; and...during the elevatory movements there is but a small chance of durable fossiliferous deposits accumulating" (loc. cit., page 139).) Chapter VI.--Perhaps some facts on metamorphism, but chiefly on the layers in mica-slate, etc., being analogous to cleavage. Chapter VII.--The grand up-and-down movements (and vertical silicified trees) in the Cordillera: see summary, page 204 and page 240. Origin of the Claystone porphyry formation, page 170. Chapter VIII., page 224.--Mixture of Cretaceous and Oolitic forms (page 226)--great subsidence. I think (page 232) there is some novelty in discussion on axes of eruption and injection. (page 247) Continuous volcanic action in the Cordillera. I think the concluding summary (page 237) would show what are the most salient features in the book. LETTER 557. TO C. LYELL. Shrewsbury [August 10th, 1846]. I was delighted to receive your letter, which was forwarded here to me. I am very glad to hear about the new edition of the "Principles," (557/1. The seventh edition of the "Principles of Geology" was published in 1847.), and I most heartily hope you may live to bring out half a dozen more editions. There would not have been such books as d'Orbigny's S. American Geology (557/2. "Voyage dans l'Amerique meridionale execute pendant les Annees 1826-37." 6 volumes, Paris, 1835-43.) published, if there had been seven editions of the "Principles" distributed in France. I am rather sorry about the small type; but the first edition, my old true love, which I never deserted for the later editions, was also in small type. I much fear I shall not be able to give any assistance to Book III. (557/3. This refers to Book III. of the "Principles"--"Changes of the Organic World now in Progress.") I think I formerly gave my few criticisms, but I will read it over again very soon (though I am striving to finish my S. American Geology (557/4. "Geological Observations on South America" was published in 1846.)) and see whether I can give you any references. I have been thinking over the subject, and can remember no one book of consequence, as all my materials (which are in an absolute chaos on separate bits of paper) have been picked out of books not directly treating of the subjects you have discussed, and which I hope some day to attempt; thus Hooker's "Antarctic Flora" I have found eminently useful (557/5. "Botany of the Antarctic Voyage of H.M.S. 'Erebus' and 'Terror' in the Years 1839-43." I., "Flora Antarctica." 2 volumes, London, 1844-47.), and yet I declare I do not know what precise facts I could refer you to. Bronn's "Geschichte" (557/6. "Naturgeschichte der drei Reiche." H.E. Bronn, Stuttgart, 1834-49.) which you once borrowed) is the only systematic book I have met with on such subjects; and there are no general views in such parts as I have read, but an immense accumulation of references, very useful to follow up, but not credible in themselves: thus he gives hybrids from ducks and fowls just as readily as between fowls and pheasants! You can have it again if you like. I have no doubt Forbes' essay, which is, I suppose, now fairly out, will be very good under geographical head. (557/7. "On the Connection between the Distribution of the existing Fauna and Flora of the British Isles, and the Geological Changes which have affected their Area, especially during the Epoch of the Northern Drift," by E. Forbes. "Memoirs of Geological Survey," Volume I., page 336, 1846.) Kolreuter's German book is excellent on hybrids, but it will cost you a good deal of time to work out any conclusion from his numerous details. (557/8. Joseph Gottlieb Kolreuter's "Vorlaufige Nachricht von eininigen das Geschlecht der Pflanzen betreffenden Versuchen und Beobachtungen." Leipzig, 1761.) With respect to variation I have found nothing--but minute details scattered over scores of volumes. But I will look over Book III. again. What a quantity of work you have in hand! I almost wish you could have finished America, and thus have allowed yourself rather more time for the old "Principles"; and I am quite surprised that you could possibly have worked your own new matter in within six weeks. Your intention of being in Southampton will much strengthen mine, and I shall be very glad to hear some of your American Geology news. LETTER 558. TO L. HORNER. Down, Sunday [January 1847]. Your most agreeable praise of my book is enough to turn my head; I am really surprised at it, but shall swallow it with very much gusto... (558/1. "Geological Observations in S. America," London, 1846.) E. de Beaumont measured the inclination with a sextant and artificial horizon, just as you take the height of the sun for latitude. With respect to my Journal, I think the sketches in the second edition (558/2. "Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of H.M.S. 'Beagle.'" Edition II. London, 1845.) are pretty accurate; but in the first they are not so, for I foolishly trusted to my memory, and was much annoyed to find how hasty and inaccurate many of my remarks were, when I went over my huge pile of descriptions of each locality. If ever you meet anyone circumstanced as I was, advise him not, on any account, to give any sketches until his materials are fully worked out. What labour you must be undergoing now; I have wondered at your patience in having written to me two such long notes. How glad Mrs. Horner will be when your address is completed. (558/3. Anniversary Address of the President ("Quart. Journ. Geol. Soc." Volume III., page xxii, 1847).) I must say that I am much pleased that you will notice my volume in your address, for former Presidents took no notice of my two former volumes. I am exceedingly glad that Bunbury is going on well. LETTER 559. TO C. LYELL. Down, July 3rd [1849]. I don't know when I have read a book so interesting (559/1. "A Second Visit to the United States of North America." 2 volumes, London, 1849.); some of your stories are very rich. You ought to be made Minister of Public Education--not but what I should think even that beneath the author of the old "Principles." Your book must, I should think, do a great deal of good and set people thinking. I quite agree with the "Athenaeum" that you have shown how a man of science can bring his powers of observation to social subjects. (559/2. "Sir Charles Lyell, besides the feelings of a gentleman, seems to carry with him the best habits of scientific observation into other strata than those of clay, into other 'formations' than those of rock or river-margin." "The Athenaeum," June 23rd, 1849, page 640.) You have made H. Wedgwood, heart and soul, an American; he wishes the States would annex us, and was all day marvelling how anyone who could pay his passage money was so foolish as to remain here. LETTER 560. TO C. LYELL. Down, [December, 1849]. (560/1. In this letter Darwin criticises Dana's statements in his volume on "Geology," forming Volume X. of the "Wilkes Exploring Expedition," 1849.) ...Dana is dreadfully hypothetical in many parts, and often as "d--d cocked sure" as Macaulay. He writes however so lucidly that he is very persuasive. I am more struck with his remarks on denudation than you seem to be. I came to exactly the same conclusion in Tahiti, that the wonderful valleys there (on the opposite extreme of the scale of wonder [to] the valleys of New South Wales) were formed exclusively by fresh water. He underrates the power of sea, no doubt, but read his remarks on valleys in the Sandwich group. I came to the conclusion in S. America (page 67) that the main effect of fresh water is to deepen valleys, and sea to widen them; I now rather doubt whether in a valley or fiord...the sea would deepen the rock at its head during the elevation of the land. I should like to tour on the W. coast of Scotland, and attend to this. I forget how far generally the shores of fiords (not straits) are cliff-formed. It is a most interesting subject. I return once again to Coral. I find he does not differ so much in detail with me regarding areas of subsidence; his map is coloured on some quite unintelligible principle, and he deduces subsidence from the vaguest grounds, such as that the N. Marianne Islands must have subsided because they are small, though long in volcanic action: and that the Marquesas subsided because they are penetrated by deep bays, etc., etc. I utterly disbelieve his statements that most of the atolls have been lately raised a foot or two. He does not condescend to notice my explanation for such appearances. He misrepresents me also when he states that I deduce, without restriction, elevation from all fringing reefs, and even from islands without any reefs! If his facts are true, it is very curious that the atolls decrease in size in approaching the vast open ocean S. of the Sandwich Islands. Dana puts me in a passion several times by disputing my conclusions without condescending to allude to my reasons; thus, regarding S. Lorenzo elevation, he is pleased to speak of my "characteristic accuracy" (560/2. Dana's "Geology" (Wilkes expedition), page 590.), and then gives difficulties (as if his own) when they are stated by me, and I believe explained by me--whereas he only alludes to a few of the facts. So in Australian valleys, he does not allude to my several reasons. But I am forgetting myself and running on about what can only interest myself. He strikes me as a very clever fellow; I wish he was not quite so grand a generaliser. I see little of interest except on volcanic action and denudation, and here and there scattered remarks; some of the later chapters are very bald. LETTER 561. TO J.D. DANA. Down, December 5th, 1849. I have not for some years been so much pleased as I have just been by reading your most able discussion on coral reefs. I thank you most sincerely for the very honourable mention you make of me. (561/1. "United States Exploring Expedition during the Years 1839-42 under the Command of Charles Wilkes, U.S.N." Volume X., "Geology," by J.D. Dana, 1849.) This day I heard that the atlas has arrived, and this completes your munificent present to me. I have not yet come to the chapter on subsidence, and in that I fancy we shall disagree, but in the descriptive part our agreement has been eminently satisfactory to me, and far more than I ever ventured to anticipate. I consider that now the subsidence theory is established. I have read about half through the descriptive part of the "Volcanic Geology" (561/2. Part of Dana's "Geology" is devoted to volcanic action.) (last night I ascended the peaks of Tahiti with you, and what I saw in my short excursion was most vividly brought before me by your descriptions), and have been most deeply interested by it. Your observations on the Sandwich craters strike me as the most important and original of any that I have read for a long time. Now that I have read yours, I believe I saw at the Galapagos, at a distance, instances of those most curious fissures of eruption. There are many points of resemblance between the Galapagos and Sandwich Islands (even to the shape of the mound-like hills)--viz., in the liquidity of the lavas, absence of scoriae, and tuff-craters. Many of your scattered remarks on denudation have particularly interested me; but I see that you attribute less to sea and more to running water than I have been accustomed to do. After your remarks in your last very kind letter I could not help skipping on to the Australian valleys (561/3. Ibid., pages 526 et seq.: "The Formation of Valleys, etc., in New South Wales."), on which your remarks strike me as exceedingly ingenious and novel, but they have not converted me. I cannot conceive how the great lateral bays could have been scooped out, and their sides rendered precipitous by running water. I shall go on and read every word of your excellent volume. If you look over my "Geological Instructions" you will be amused to see that I urge attention to several points which you have elaborately discussed. (561/4. "A Manual of Scientific Enquiry, prepared for the use of Her Majesty's Navy, and adapted for Travellers in General." Edited by Sir John F.W. Herschel, Bart. London, 1849 (Section VI., "Geology." By Charles Darwin).) I lately read a paper of yours on Chambers' book, and was interested by it. I really believe the facts of the order described by Chambers, in S. America, which I have described in my Geolog. volume. This leads me to ask you (as I cannot doubt that you will have much geological weight in N. America) to look to a discussion at page 135 in that volume on the importance of subsidence to the formation of deposits, which are to last to a distant age. This view strikes me as of some importance. When I meet a very good-natured man I have that degree of badness of disposition in me that I always endeavour to take advantage of him; therefore I am going to mention some desiderata, which if you can supply I shall be very grateful, but if not no answer will be required. Thank you for your "Conspectus Crust.," but I am sorry to say I am not worthy of it, though I have always thought the Crustacea a beautiful subject. (561/5. "Conspectus Crustaceorum in orbis terrarum circumnavigatione, C. Wilkes duce, collectorum." Cambridge (U.S.A.), 1847.) LETTER 562. TO C. LYELL. [Down, March 9th, 1850.] I am uncommonly much obliged to you for your address, which I had not expected to see so soon, and which I have read with great interest. (562/1. Anniversary Address of the President, "Quart. Journ. Geol. Soc." Volume VI., page 32, 1850.) I do not know whether you spent much time over it, but it strikes me as extra well arranged and written--done in the most artistic manner, to use an expression which I particularly hate. Though I am necessarily pretty well familiar with your ideas from your conversation and books, yet the whole had an original freshness to me. I am glad that you broke through the routine of the President's addresses, but I should be sorry if others did. Your criticisms on Murchison were to me, and I think would be to many, particularly acceptable. (562/2. In a paper "On the Geological Structure of the Alps, etc." ("Quart. Journ. Geol. Soc." Volume V., page 157, 1849) Murchison expressed his belief that the apparent inversion of certain Tertiary strata along the flanks of the Alps afforded "a clear demonstration of a sudden operation or catastrophe." It is this view of paroxysmal energy that Lyell criticises in the address.) Capital, that metaphor of the clock. (562/3. "In a word, the movement of the inorganic world is obvious and palpable, and might be likened to the minute-hand of a clock, the progress of which can be seen and heard, whereas the fluctuations of the living creation are nearly invisible, and resemble the motion of the hour-hand of a timepiece" (loc. cit., page xlvi).) I shall next February be much interested by seeing your hour-hand of the organic world going. Many thanks for your kindness in taking the trouble to tell me of the anniversary dinner. What a compliment that was which Lord Mahon paid me! I never had so great a one. He must be as charming a man as his wife is a woman, though I was formerly blind to his merit. Bunsen's speech must have been very interesting and very useful, if any orthodox clergyman were present. Your metaphor of the pebbles of pre-existing languages reminds me that I heard Sir J. Herschel at the Cape say how he wished some one would treat language as you had Geology, and study the existing causes of change, and apply the deduction to old languages. We are all pretty flourishing here, though I have been retrograding a little, and I think I stand excitement and fatigue hardly better than in old days, and this keeps me from coming to London. My cirripedial task is an eternal one; I make no perceptible progress. I am sure that they belong to the hour-hand, and I groan under my task. LETTER 563. C. LYELL TO CHARLES DARWIN. April 23rd, 1855. I have seen a good deal of French geologists and palaeontologists lately, and there are many whom I should like to put on the R.S. Foreign List, such as D'Archiac, Prevost, and others. But the man who has made the greatest sacrifices and produced the greatest results, who has, in fact, added a new period to the calendar, is Barrande. The importance of his discoveries as they stand before the public fully justify your choice of him; but what is unpublished, and which I have seen, is, if possible, still more surprising. Thirty genera of gasteropods (150 species) and 150 species of lamellibranchiate bivalves in the Silurian! All obtained by quarries opened solely by him for fossils. A man of very moderate fortune spending nearly all his capital on geology, and with success. E. Forbes' polarity doctrines are nearly overturned by the unpublished discoveries of Barrande. (563/1. See note, Letter 41, Volume I.) I have called Barrande's new period Cambrian (see "Manual," 5th edition), and you will see why. I could not name it Protozoic, but had Barrande called it Bohemian, I must have adopted that name. All the French will rejoice if you confer an honour on Barrande. Dana is well worthy of being a foreign member. Should you succeed in making Barrande F.R.S., send me word. LETTER 564. TO J.D. HOOKER. June 5th [1857]. (564/1. The following, which bears on the subject of medals, forms part of the long letter printed in the "Life and Letters," II., page 100.) I do not quite agree with your estimate of Richardson's merits. Do, I beg you (whenever you quietly see), talk with Lyell on Prestwich: if he agrees with Hopkins, I am silenced; but as yet I must look at the correlation of the Tertiaries as one of the highest and most frightfully difficult tasks a man could set himself, and excellent work, as I believe, P. has done. (564/2. Prof. Prestwich had published numerous papers dealing with Tertiary Geology before 1857. The contributions referred to are probably those "On the Correlation of the Lower Tertiaries of England with those of France and Belgium," "Quart. Journ. Geol. Soc." Volume X., 1854, page 454; and "On the Correlation of the Middle Eocene Tertiaries of England, France, and Belgium," ibid., XII., 1856, page 390.) I confess I do not value Hopkins' opinion on such a point. I confess I have never thought, as you show ought to be done, on the future. I quite agree, under all circumstances, with the propriety of Lindley. How strange no new geologists are coming forward! Are there not lots of good young chemists and astronomers or physicists? Fitton is the only old geologist left who has done good work, except Sedgwick. Have you thought of him? He would be a brilliant companion for Lindley. Only it would never do to give Lyell a Copley and Sedgwick a Royal in the same year. It seems wrong that there should be three Natural Science medals in the same year. Lindley, Sedgwick, and Bunsen sounds well, and Lyell next year for the Copley. (564/3. In 1857 a Royal medal was awarded to John Lindley; Lyell received the Copley in 1858, and Bunsen in 1860.) You will see that I am speculating as a mere idle amateur. LETTER 565. TO S.P. WOODWARD. Down, May 27th [1856]. I am very much obliged to you for having taken the trouble to answer my query so fully. I can now be at rest, for from what you say and from what little I remember Forbes said, my point is unanswerable. The case of Terebratula is to the point as far as it goes, and is negative. I have already attempted to get a solution through geographical distribution by Dr. Hooker's means, and he finds that the same genera which have very variable species in Europe have other very variable species elsewhere. This seems the general rule, but with some few exceptions. I see from the several reasons which you assign, that there is no hope of comparing the same genus at two different periods, and seeing whether the tendency to vary is greater at one period in such genus than at another period. The variability of certain genera or groups of species strikes me as a very odd fact. (565/1. The late Dr. Neumayr has dealt, to some extent, with this subject in "Die Stamme des Thierreichs," Volume I., Wien, 1889.) I shall have no points, as far as I can remember, to suggest for your reconsideration, but only some on which I shall have to beg for a little further information. However, I feel inclined very much to dispute your doctrine of islands being generally ancient in comparison, I presume, with continents. I imagine you think that islands are generally remnants of old continents, a doctrine which I feel strongly disposed to doubt. I believe them generally rising points; you, it seems, think them sinking points. LETTER 566. TO T.H. HUXLEY. Down, April 14th [1860]. Many thanks for your kind and pleasant letter. I have been much interested by "Deep-sea Soundings,", and will return it by this post, or as soon as I have copied a few sentences. (566/1. Specimens of the mud dredged by H.M.S. "Cyclops" were sent to Huxley for examination, who gave a brief account of them in Appendix A of Capt. Dayman's Report, 1858, under the title "Deep-sea Soundings in the North Atlantic.") I think you said that some one was investigating the soundings. I earnestly hope that you will ask the some one to carefully observe whether any considerable number of the calcareous organisms are more or less friable, or corroded, or scaling; so that one might form some crude notion whether the deposition is so rapid that the foraminifera are preserved from decay and thus are forming strata at this profound depth. This is a subject which seems to me to have been much neglected in examining soundings. Bronn has sent me two copies of his Morphologische Studien uber die Gestaltungsgesetze." (H.G. Bronn, "Morphologische Studien uber die Gestaltungsgesetze der Naturkorper uberhaupt und der organischen insbesondere": Leipzig, 1858.) It looks elementary. If you will write you shall have the copy; if not I will give it to the Linnean Library. I quite agree with the letter from Lyell that your extinguished theologians lying about the cradle of each new science, etc., etc., is splendid. (566/2. "Darwiniana, Collected Essays," Volume II., page 52.) LETTER 567. TO T.H. HUXLEY. May 10th [1862 or later]. I have been in London, which has prevented my writing sooner. I am very sorry to hear that you have been ill: if influenza, I can believe in any degree of prostration of strength; if from over-work, for God's sake do not be rash and foolish. You ask for criticisms; I have none to give, only impressions. I fully agree with your "skimming-of-pot theory," and very well you have put it. With respect [to] contemporaneity I nearly agree with you, and if you will look to the d--d book, 3rd edition, page 349 you will find nearly similar remarks. (567/1. "When the marine forms are spoken of as having changed simultaneously throughout the world, it must not be supposed that this expression relates to the same year, or to the same century, or even that it has a very strict geological sense; for if all the marine animals now living in Europe, and all those that lived in Europe during the Pleistocene period (a very remote period as measured by years, including the whole Glacial epoch), were compared with those now existing in South America or in Australia, the most skilful naturalist would hardly be able to say whether the present or the Pleistocene inhabitants of Europe resembled most closely those of the Southern hemisphere." "Origin," Edition VI., page 298. The passage in Edition III., page 350, is substantially the same.) But at page 22 of your Address, in my opinion you put your ideas too far. (567/2. Anniversary Address to the Geological Society of London ("Quart. Journ. Geol. Soc." Volume XVIII., page xl, 1862). As an illustration of the misleading use of the term "contemporaneous" as employed by geologists, Huxley gives the following illustration: "Now suppose that, a million or two of years hence, when Britain has made another dip beneath the sea and has come up again, some geologist applies this doctrine [i.e., the doctrine of the Contemporaneity of the European and of the North American Silurians: proof of contemporaneity is considered to be established by the occurrence of 60 per cent. of species in common], in comparing the strata laid bare by the upheaval of the bottom, say, of St. George's Channel with what may then remain of the Suffolk Crag. Reasoning in the same way, he will at once decide the Suffolk Crag and the St. George's Channel beds to be contemporaneous; although we happen to know that a vast period...of time...separates the two" (loc. cit., page xlv). This address is republished in the "Collected Essays," Volume VIII.; the above passage is at page 284.) I cannot think that future geologists would rank the Suffolk and St. George's strata as contemporaneous, but as successive sub-stages; they rank N. America and British stages as contemporaneous, notwithstanding a percentage of different species (which they, I presume, would account for by geographical difference) owing to the parallel succession of the forms in both countries. For terrestrial productions I grant that great errors may creep in (567/3. Darwin supposes that terrestrial productions have probably not changed to the same extent as marine organisms. "If the Megatherium, Mylodon...had been brought to Europe from La Plata, without any information in regard to their geological position, no one would have suspected that they had co-existed with sea shells all still living" ("Origin," Edition VI., page 298).); but I should require strong evidence before believing that, in countries at all well-known, so-called Silurian, Devonian, and Carboniferous strata could be contemporaneous. You seem to me on the third point, viz., on non-advancement of organisation, to have made a very strong case. I have not knowledge or presumption enough to criticise what you say. I have said what I could at page 363 of "Origin." It seems to me that the whole case may be looked at from several points of view. I can add only one miserable little special case of advancement in cirripedes. The suspicion crosses me that if you endeavoured your best you would say more on the other side. Do you know well Bronn in his last Entwickelung (or some such word) on this subject? it seemed to me very well done. (567/4. Probably "Untersuchungen uber die Entwickelungsgesetze der organischen Welt wahrend der Bildungszeit unserer Erdoberflache," Stuttgart, 1858. Translated by W.S. Dallas in the "Ann. and Mag. Nat. Hist." Volume IV., page 81.) I hope before you publish again you will read him again, to consider the case as if you were a judge in a court of appeal; it is a very important subject. I can say nothing against your side, but I have an "inner consciousness" (a highly philosophical style of arguing!) that something could be said against you; for I cannot help hoping that you are not quite as right as you seem to be. Finally, I cannot tell why, but when I finished your Address I felt convinced that many would infer that you were dead against change of species, but I clearly saw that you were not. I am not very well, so good-night, and excuse this horrid letter. LETTER 568. TO J.D. HOOKER. Down, June 30th [1866]. I have heard from Sulivan (who, poor fellow, gives a very bad account of his own health) about the fossils (568/1. In a letter to Huxley (June 4th, 1866) Darwin wrote: "Admiral Sulivan several years ago discovered an astonishingly rich accumulation of fossil bones not far from the Straits [of Magellan]...During many years it has seemed to me extremely desirable that these should be collected; and here is an excellent opportunity.")... The place is Gallegos, on the S. coast of Patagonia. Sulivan says that in the course of two or three days all the boats in the ship could be filled twice over; but to get good specimens out of the hardish rock two or three weeks would be requisite. It would be a grand haul for Palaeontology. I have been thinking over your lecture. (568/2. A lecture on "Insular Floras" given at the British Association meeting at Nottingham, August 27th, 1866, published in the "Gard. Chron." 1867.) Will it not be possible to give enlarged drawings of some leading forms of trees? You will, of course, have a large map, and George tells me that he saw at Sir H. James', at Southampton, a map of the world on a new principle, as seen from within, so that almost 4/5ths of the globe was shown at once on a large scale. Would it not be worth while to borrow one of these from Sir H. James as a curiosity to hang up? Remember you are to come here before Nottingham. I have almost finished the last number of H. Spencer, and am astonished at its prodigality of original thought. But the reflection constantly recurred to me that each suggestion, to be of real value to science, would require years of work. It is also very unsatisfactory, the impossibility of conjecturing where direct action of external circumstances begins and ends--as he candidly owns in discussing the production of woody tissue in the trunks of trees on the one hand, and on the other in spines and the shells of nuts. I shall like to hear what you think of this number when we meet. LETTER 569. TO A. GAUDRY. Down, November 17th, 1868. On my return home after a short absence I found your note of Nov. 9th, and your magnificent work on the fossil animals of Attica. (569/1. The "Geologie de l'Attique," 2 volumes 4to, 1862-7, is the only work of Gaudry's of this date in Mr. Darwin's library.) I assure you that I feel very grateful for your generosity, and for the honour which you have thus conferred on me. I know well, from what I have already read of extracts, that I shall find your work a perfect mine of wealth. One long passage which Sir C. Lyell quotes from you in the 10th and last edition of the "Principles of Geology" is one of the most striking which I have ever read on the affiliation of species. (569/2. The quotation in Lyell's "Principles," Edition X., Volume II., page 484, is from M. Gaudry's "Animaux Fossiles de Pikermi," 1866, page 34:-- "In how different a light does the question of the nature of species now present itself to us from that in which it appeared only twenty years ago, before we had studied the fossil remains of Greece and the allied forms of other countries. How clearly do these fossil relics point to the idea that species, genera, families, and orders now so distinct have had common ancestors. The more we advance and fill up the gaps, the more we feel persuaded that the remaining voids exist rather in our knowledge than in nature. A few blows of the pickaxe at the foot of the Pyrenees, of the Himalaya, of Mount Pentelicus in Greece, a few diggings in the sandpits of Eppelsheim, or in the Mauvaises Terres of Nebraska, have revealed to us the closest connecting links between forms which seemed before so widely separated. How much closer will these links be drawn when Palaeontology shall have escaped from its cradle!") LETTER 570. A. SEDGWICK TO CHARLES DARWIN. (570/1. In May, 1870, Darwin "went to the Bull Hotel, Cambridge, to see the boys, and for a little rest and enjoyment." (570/2. See "Life and Letters," III., 125.) The following letter was received after his return to Down.) Trinity College, Cambridge, May 30th, 1870. My dear Darwin, Your very kind letter surprised me. Not that I was surprised at the pleasant and very welcome feeling with which it was written. But I could not make out what I had done to deserve the praise of "extraordinary kindness to yourself and family." I would most willingly have done my best to promote the objects of your visit, but you gave me no opportunity of doing so. I was truly grieved to find that my joy at seeing you again was almost too robust for your state of nerves, and that my society, after a little while, became oppressive to you. But I do trust that your Cambridge visit has done you no constitutional harm; nay, rather that it has done you some good. I only speak honest truth when I say that I was overflowing with joy when I saw you, and saw you in the midst of a dear family party, and solaced at every turn by the loving care of a dear wife and daughters. How different from my position--that of a very old man, living in cheerless solitude! May god help and cheer you all with the comfort of hopeful hearts--you and your wife, and your sons and daughters! You were talking about my style of writing,--I send you my last specimen, and it will probably continue to be my last. It is the continuation of a former pamphlet of which I have not one spare copy. I do not ask you to read it. It is addressed to the old people in my native Dale of Dent, on the outskirts of Westmorland. While standing at the door of the old vicarage, I can see down the valley the Lake mountains--Hill Bell at the head of Windermere, about twenty miles off. On Thursday next (D.V.) I am to start for Dent, which I have not visited for full two years. Two years ago I could walk three or four miles with comfort. Now, alas! I can only hobble about on my stick. I remain your true-hearted old friend A. Sedgwick. LETTER 571. TO C. LYELL. Down, September 3rd [1874]. Many thanks for your very kind and interesting letter. I was glad to hear at Southampton from Miss Heathcote a good account of your health and strength. With respect to the great subject to which you refer in your P.S., I always try to banish it from my mind as insoluble; but if I were circumstanced as you are, no doubt it would recur in the dead of the night with painful force. Many persons seem to make themselves quite easy about immortality (571/1. See "Life and Letters," I., page 312.) and the existence of a personal God, by intuition; and I suppose that I must differ from such persons, for I do not feel any innate conviction on any such points. We returned home about ten days ago from Southampton, and I enjoyed my holiday, which did me much good. But already I am much fatigued by microscope and experimental work with insect-eating plants. When at Southampton I was greatly interested by looking at the odd gravel deposits near at hand, and speculating about their formation. You once told me something about them, but I forget what; and I think that Prestwich has written on the superficial deposits on the south coasts, and I must find out his paper and read it. (571/2. Prof. Prestwich contributed several papers to the Geological Society on the Superficial Deposits of the South of England.) From what I have seen of Mr. Judd's papers I have thought that he would rank amongst the few leading British geologists. LETTER 572. TO J.D. HOOKER. (572/1. The following letter was written before Mr. Darwin knew that Sir Charles Lyell was to be buried in Westminster Abbey, a memorial which thoroughly satisfied him. See "Life and Letters," III., 197.) Down, February 23rd, 1875. I have just heard from Miss Buckley of Lyell's death. I have long felt opposed to the present rage for testimonials; but when I think how Lyell revolutionised Geology, and aided in the progress of so many other branches of science, I wish that something could be done in his honour. On the other hand it seems to me that a poor testimonial would be worse than none; and testimonials seem to succeed only when a man has been known and loved by many persons, as in the case of Falconer and Forbes. Now, I doubt whether of late years any large number of scientific men did feel much attachment towards Lyell; but on this head I am very ill fitted to judge. I should like to hear some time what you think, and if anything is proposed I should particularly wish to join in it. We have both lost as good and as true a friend as ever lived. LETTER 573. TO J.D. HOOKER. (573/1. This letter shows the difficulty which the inscription for Sir Charles Lyell's memorial gave his friends. The existing inscription is, "Charles Lyell...Author of 'The Principles of Geology'...Throughout a long and laborious life he sought the means of deciphering the fragmentary records of the Earth's history in the patient investigation of the present order of Nature, enlarging the boundaries of knowledge, and leaving on Scientific thought an enduring influence..." Down, June 21st [1876]. I am sorry for you about the inscription, which has almost burst me. We think there are too many plurals in yours, and when read aloud it hisses like a goose. I think the omission of some words makes it much stronger. "World" (573/2. The suggested sentence runs: "he gave to the world the results of his labour, etc.") is much stronger and truer than "public." As Lyell wrote various other books and memoirs, I have some little doubt about the "Principles of Geology." People here do not like your "enduring value": it sounds almost an anticlimax. They do not much like my "last (or endure) as long as science lasts." If one reads a sentence often enough, it always becomes odious. God help you. LETTER 574. TO OSWALD HEER. Down, March 8th [1875]. I thank you for your very kind and deeply interesting letter of March 1st, received yesterday, and for the present of your work, which no doubt I shall soon receive from Dr. Hooker. (574/1. "Flora Fossilis Arctica," Volume III., 1874, sent by Prof. Heer through Sir Joseph Hooker.) The sudden appearance of so many Dicotyledons in the Upper Chalk appears to me a most perplexing phenomenon to all who believe in any form of evolution, especially to those who believe in extremely gradual evolution, to which view I know that you are strongly opposed. (574/2. The volume referred to contains a paper on the Cretaceous Flora of the Arctic Zone (Spitzbergen and Greenland), in which several dicotyledonous plants are described. In a letter written by Heer to Darwin the author speaks of a species of poplar which he describes as the oldest Dicotyledon so far recorded.) The presence of even one true Angiosperm in the Lower Chalk makes me inclined to conjecture that plants of this great division must have been largely developed in some isolated area, whence owing to geographical changes, they at last succeeded in escaping, and spread quickly over the world. (574/3. No satisfactory evidence has so far been brought forward of the occurrence of fossil Angiosperms in pre-Cretaceous rocks. The origin of the Monocotyledons and Dicotyledons remains one of the most difficult and attractive problems of Palaeobotany.) (574/4. See Letters 395, 398.) But I fully admit that this case is a great difficulty in the views which I hold. Many as have been the wonderful discoveries in Geology during the last half-century, I think none have exceeded in interest your results with respect to the plants which formerly existed in the Arctic regions. How I wish that similar collections could be made in the Southern hemisphere, for instance in Kerguelen's Land. The death of Sir C. Lyell is a great loss to science, but I do not think to himself, for it was scarcely possible that he could have retained his mental powers, and he would have suffered dreadfully from their loss. The last time I saw him he was speaking with the most lively interest about his last visit to you, and I was grieved to hear from him a very poor account of your health. I have been working for some time on a special subject, namely insectivorous plants. I do not know whether the subject will interest you, but when my book is published I will have the pleasure of sending you a copy. I am very much obliged for your photograph, and enclose one of myself. LETTER 574*. TO S.B.J. SKERTCHLY. March 2nd, 1878. It is the greatest possible satisfaction to a man nearly at the close of his career to believe that he has aided or stimulated an able and energetic fellow-worker in the noble cause of science. Therefore your letter has deeply gratified me. I am writing this away from home, as my health failed, and I was forced to rest; and this will account for the delay in answering your letter. No doubt on my return home I shall find the memoir which you have kindly sent me. I shall read it with much interest, as I have heard something of your work from Prof. Geikie, and have read his admirable "Ice Age." (574/5. "The Great Ice Age and its Relation to the Antiquity of Man": London, 1874. By James Geikie.) I have noticed the criticisms on your work, but such opposition must be expected by every one who draws fine grand conclusions, and such assuredly are yours as abstracted in your letter. (574/6. Mr. S.B.J. Skertchly recorded "the discovery of palaeolithic flint implements, mammalian bones, and fresh-water shells in brick-earths below the Boulder-clay of East Anglia," in a letter published in the "Geol. Mag." Volume III., page 476, 1876. (See also "The Fenland, Past and Present." S.H. Miller and S.B.J. Skertchly, London, 1878.) The conclusions of Mr. Skertchly as to the pre-Glacial age of the flint implements were not accepted by some authorities. (See correspondence in "Nature," Volume XV., 1877, pages 141, 142.) We are indebted to Mr. Marr for calling our attention to Mr. Skertchly's discovery.) What magnificent progress Geology has made within my lifetime! I shall have very great pleasure in sending you any of my books with my autograph, but I really do not know which to send. It will cost you only the trouble of a postcard to tell me which you would like, and it shall soon be sent. Forgive this untidy note, as it is rather an effort to write. With all good wishes for your continued success in science and for your happiness... CHAPTER 2.X.--BOTANY, 1843-1871. 2.X.I. Miscellaneous.--2.X.II. Melastomaceae.--2.X.III. Correspondence with John Scott. 2.X.I. MISCELLANEOUS, 1843-1862. (PLATE: SIR JOSEPH HOOKER, 1897. From a Photograph by W.J. Hawker Wimborne. Walker & Cockerell, ph. sc.) LETTER 575. TO WILLIAM JACKSON HOOKER. Down, March 12th [1843]. ...When you next write to your son, will you please remember me kindly to him and give him my best thanks for his note? I had the pleasure yesterday of reading a letter from him to Mr. Lyell of Kinnordy, full of the most interesting details and descriptions, and written (if I may be permitted to make such a criticism) in a particularly agreeable style. It leads me anxiously to hope, even more than I did before, that he will publish some separate natural history journal, and not allow (if it can be avoided) his materials to be merged in another work. I am very glad to hear you talk of inducing your son to publish an Antarctic Flora. I have long felt much curiosity for some discussion on the general character of the flora of Tierra del Fuego, that part of the globe farthest removed in latitude from us. How interesting will be a strict comparison between the plants of these regions and of Scotland and Shetland. I am sure I may speak on the part of Prof. Henslow that all my collection (which gives a fair representation of the Alpine flora of Tierra del Fuego and of Southern Patagonia) will be joyfully laid at his disposal. LETTER 576. TO JOHN LINDLEY. Down, Saturday [April 8th, 1843]. I take the liberty, at the suggestion of Dr. Royle, of forwarding to you a few seeds, which have been found under very singular circumstances. They have been sent to me by Mr. W. Kemp, of Galashiels, a (partially educated) man, of whose acuteness and accuracy of observation, from several communications on geological subjects, I have a VERY HIGH opinion. He found them in a layer under twenty-five feet thickness of white sand, which seems to have been deposited on the margins of an anciently existing lake. These seeds are not known to the provincial botanists of the district. He states that some of them germinated in eight days after being planted, and are now alive. Knowing the interest you took in some raspberry seeds, mentioned, I remember, in one of your works, I hope you will not think me troublesome in asking you to have these seeds carefully planted, and in begging you so far to oblige me as to take the trouble to inform me of the result. Dr. Daubeny has started for Spain, otherwise I would have sent him some. Mr. Kemp is anxious to publish an account of his discovery himself, so perhaps you will be so kind as to communicate the result to me, and not to any periodical. The chance, though appearing so impossible, of recovering a plant lost to any country if not to the world, appears to me so very interesting, that I hope you will think it worth while to have these seeds planted, and not returned to me. LETTER 577. TO C. LYELL. [September, 1843.] An interesting fact has lately, as it were, passed through my hands. A Mr. Kemp (almost a working man), who has written on "parallel roads," and has corresponded with me (577/1. In a letter to Henslow, Darwin wrote: "If he [Mr. Kemp] had not shown himself a most careful and ingenious observer, I should have thought nothing of the case."), sent me in the spring some seeds, with an account of the spot where they were found, namely, in a layer at the bottom of a deep sand pit, near Melrose, above the level of the river, and which sand pit he thinks must have been accumulated in a lake, when the whole features of the valleys were different, ages ago; since which whole barriers of rock, it appears, must have been worn down. These seeds germinated freely, and I sent some to the Horticultural Society, and Lindley writes to me that they turn out to be a common Rumex and a species of Atriplex, which neither he nor Henslow (as I have since heard) have ever seen, and certainly not a British plant! Does this not look like a vivification of a fossil seed? It is not surprising, I think, that seeds should last ten or twenty thousand [years], as they have lasted two or three [thousand years] in the Druidical mounds, and have germinated. When not building, I have been working at my volume on the volcanic islands which we visited; it is almost ready for press...I hope you will read my volume, for, if you don't, I cannot think of anyone else who will! We have at last got our house and place tolerably comfortable, and I am well satisfied with our anchorage for life. What an autumn we have had: completely Chilian; here we have had not a drop of rain or a cloudy day for a month. I am positively tired of the fine weather, and long for the sight of mud almost as much as I did when in Peru. (577/2. The vitality of seeds was a subject in which Darwin continued to take an interest. In July, 1855 ("Life and Letters," II., page 65), he wrote to Hooker: "A man told me the other day of, as I thought, a splendid instance--and splendid it was, for according to his evidence the seed came up alive out of the lower part of the London Clay! I disgusted him by telling him that palms ought to have come up." In the "Gardeners' Chronicle," 1855, page 758, appeared a notice (half a column in length) by Darwin on the "Vitality of Seeds." The facts related refer to the "Sand-walk" at Down; the wood was planted in 1846 on a piece of pasture land laid down as grass in 1840. In 1855, on the soil being dug in several places, Charlock (Brassica sinapistrum) sprang up freely. The subject continued to interest him, and we find a note dated July 2nd, 1874, in which Darwin recorded that forty-six plants of Charlock sprang up in that year over a space (14 x 7 feet) which had been dug to a considerable depth. In the course of the article in the "Gardeners' Chronicle," Darwin remarks: "The power in seeds of retaining their vitality when buried in damp soil may well be an element in preserving the species, and therefore seeds may be specially endowed with this capacity; whereas the power of retaining vitality in a dry artificial condition must be an indirect, and in one sense accidental, quality in seeds of little or no use to the species." The point of view expressed in the letter to Lyell above given is of interest in connection with the research of Horace Brown and F. Escombe (577/3. "Proc. Roy. Soc." Volume LXII., page 160.) on the remarkable power possessed by dry seeds of resistance to the temperature of liquid air. The point of the experiment is that life continues at a temperature "below that at which ordinary chemical reactions take place." A still more striking demonstration of the fact has been made by Thiselton-Dyer and Dewar who employed liquid hydrogen as a refrigerant. (577/4. Read before the British Association (Dover), 1899, and published in the "Comptes rendus," 1899, and in the "Proc. R. Soc." LXV., page 361, 1899.) The connection between these facts and the dormancy of buried seeds is only indirect; but inasmuch as the experiment proves the possibility of life surviving a period in which no ordinary chemical change occurs, it is clear that they help one to believe in greatly prolonged dormancy in conditions which tend to check metabolism. For a discussion of the bearing of their results on the life-problem, and for the literature of the subject, reference should be made to the paper by Brown and Escombe. See also C. de Candolle "On Latent Life in Seeds," "Brit. Assoc. Report," 1896, page 1023 and F. Escombe, "Science Progress," Volume I., N.S., page 585, 1897.) LETTER 578. TO J.S. HENSLOW. Down, Saturday [November 5th, 1843]. I sent that weariful Atriplex to Babington, as I said I would, and he tells me that he has reared a facsimile by sowing the seeds of A. angustifolia in rich soil. He says he knows the A. hastata, and that it is very different. Until your last note I had not heard that Mr. Kemp's seeds had produced two Polygonums. He informs me he saw each plant bring up the husk of the individual seed which he planted. I believe myself in his accuracy, but I have written to advise him not to publish, for as he collected only two kinds of seeds--and from them two Polygomuns, two species or varieties of Atriplex and a Rumex have come up, any one would say (as you suggested) that more probably all the seeds were in the soil, than that seeds, which must have been buried for tens of thousands of years, should retain their vitality. If the Atriplex had turned out new, the evidence would indeed have been good. I regret this result of poor Mr. Kemp's seeds, especially as I believed, from his statements and the appearance of the seeds, that they did germinate, and I further have no doubt that their antiquity must be immense. I am sorry also for the trouble you have had. I heard the other day through a circuitous course how you are astonishing all the clodhoppers in your whole part of the county: and [what is] far more wonderful, as it was remarked to me, that you had not, in doing this, aroused the envy of all the good surrounding sleeping parsons. What good you must do to the present and all succeeding generations. (578/1. For an account of Professor Henslow's management of his parish of Hitcham see "Memoir of the Rev. John Stevens Henslow, M.A." by the Rev. Leonard Jenyns: 8vo, London, 1862.) LETTER 579. TO J.D. HOOKER. Down, November 14th [1855]. You well know how credulous I am, and therefore you will not be surprised at my believing the Raspberry story (579/1. This probably refers to Lindley's story of the germination of raspberry seeds taken from a barrow 1600 years old.): a very similar case is on record in Germany--viz., seeds from a barrow; I have hardly zeal to translate it for the "Gardeners' Chronicle." (579/2. "Vitality of Seeds," "Gardeners' Chronicle," November 17th, 1855, page 758.) I do not go the whole hog--viz., that sixty and two thousand years are all the same, for I should imagine that some slight chemical change was always going on in a seed. Is this not so? The discussions have stirred me up to send my very small case of the charlock; but as it required some space to give all details, perhaps Lindley will not insert; and if he does, you, you worse than an unbelieving dog, will not, I know, believe. The reason I do not care to try Mr. Bentham's plan is that I think it would be very troublesome, and it would not, if I did not find seed, convince me myself that none were in the earth, for I have found in my salting experiments that the earth clings to the seeds, and the seeds are very difficult to find. Whether washing would do I know not; a gold-washer would succeed, I daresay. LETTER 580. TO W.J. HOOKER. Testimonial from Charles Darwin, Esq., M.A., F.R.S. and G.S., late Naturalist to Captain Fitz-Roy's Voyage. Down House, Farnborough, August 25th, 1845. I have heard with much interest that your son, Dr. Hooker, is a candidate for the Botanical Chair at Edinburgh. From my former attendance at that University, I am aware how important a post it is for the advancement of science, and I am therefore the more anxious for your son's success, from my firm belief that no one will fulfil its duties with greater zeal or ability. Since his return from the famous Antarctic expedition, I have had, as you are aware, much communication with him, with respect to the collections brought home by myself, and on other scientific subjects; and I cannot express too strongly my admiration at the accuracy of his varied knowledge, and at his powers of generalisation. From Dr. Hooker's disposition, no one, in my opinion, is more fitted to communicate to beginners a strong taste for those pursuits to which he is himself so ardently devoted. For the sake of the advancement of Botany in all its branches, your son has my warmest wishes for his success. LETTER 581. TO J.D. HOOKER. Down, Thursday [June 11th, 1847]. Many thanks for your kindness about the lodgings--it will be of great use to me. (581/1. The British Association met at Oxford in 1847.) Please let me know the address if Mr. Jacobson succeeds, for I think I shall go on the 22nd and write previously to my lodgings. I have since had a tempting invitation from Daubeny to meet Henslow, etc., but upon the whole, I believe, lodgings will answer best, for then I shall have a secure solitary retreat to rest in. I am extremely glad I sent the Laburnum (581/2. This refers to the celebrated form known as Cytisus Adami, of which a full account is given in "Variation of Animals and Plants," Volume I., Edition II., page 413. It has been supposed to be a seminal hybrid or graft-hybrid between C. laburnum and C. purpureus. It is remarkable for bearing "on the same tree tufts of dingy red, bright yellow, and purple flowers, borne on branches having widely different leaves and manner of growth." In a paper by Camuzet in the "Annales de la Societe d'Horticulture de Paris, XIII., 1833, page 196, the author tries to show that Cytisus Adami is a seminal hybrid between C. alpinus and C. laburnum. Fuchs ("Sitz. k. Akad. Wien," Bd. 107) and Beijerinck ("K. Akad. Amsterdam," 1900) have spoken on Cytisus Adami, but throw no light on the origin of the hybrid. See letters to Jenner Weir in the present volume.): the raceme grew in centre of tree, and had a most minute tuft of leaves, which presented no unusual appearance: there is now on one raceme a terminal bilateral [i.e., half yellow, half purple] flower, and on other raceme a single terminal pure yellow and one adjoining bilateral flower. If you would like them I will send them; otherwise I would keep them to see whether the bilateral flowers will seed, for Herbert (581/3. Dean Herbert.) says the yellow ones will. Herbert is wrong in thinking there are no somewhat analogous facts: I can tell you some, when we meet. I know not whether botanists consider each petal and stamen an individual; if so, there seems to me no especial difficulty in the case, but if a flower-bud is a unit, are not their flowers very strange? I have seen Dillwyn in the "Gardeners' Chronicle," and was disgusted at it, for I thought my bilateral flowers would have been a novelty for you. (581/4. In a letter to Hooker, dated June 2nd, 1847, Darwin makes a bold suggestion as to floral symmetry:--) I send you a tuft of the quasi-hybrid Laburnum, with two kinds of flowers on same stalk, and with what strikes [me] as very curious (though I know it has been observed before), namely, a flower bilaterally different: one other, I observe, has half its calyx purple. Is this not very curious, and opposed to the morphological idea that a flower is a condensed continuous spire of leaves? Does it not look as if flowers were normally bilateral; just in the same way as we now know that the radiating star-fish, etc., are bilateral? The case reminds me of those insects with exactly half having secondary male characters and the other half female. (581/5. It is interesting to note his change of view in later years. In an undated letter written to Mr. Spencer, probably in 1873, he says: "With respect to asymmetry in the flowers themselves, I remain contented, from all that I have seen, with adaptation to visits of insects. There is, however, another factor which it is likely enough may have come into play--viz., the protection of the anthers and pollen from the injurious effects of rain. I think so because several flowers inhabiting rainy countries, as A. Kerner has lately shown, bend their heads down in rainy weather.") LETTER 582. TO J.D. HOOKER. June [1855]. (582/1. This is an early example of Darwin's interest in the movements of plants. Sleeping plants, as is well-known, may acquire a rhythmic movement differing from their natural period, but the precise experiment here described has not, as far as known, been carried out. See Pfeffer, "Periodische Bewegungen," 1875, page 32.) I thank you much for Hedysarum: I do hope it is not very precious, for, as I told you, it is for probably a most foolish purpose. I read somewhere that no plant closes its leaves so promptly in darkness, and I want to cover it up daily for half an hour, and see if I can TEACH IT to close by itself, or more easily than at first in darkness. I am rather puzzled about its transmission, from not knowing how tender it is... LETTER 583. TO J.D. HOOKER. Down, July 19th, 1856. I thank you warmly for the very kind manner with which you have taken my request. It will, in truth, be a most important service to me; for it is absolutely necessary that I should discuss single and double creations, as a very crucial point on the general origin of species, and I must confess, with the aid of all sorts of visionary hypotheses, a very hostile one. I am delighted that you will take up possibility of crossing, no botanist has done so, which I have long regretted, and I am glad to see that it was one of A. De Candolle's desiderata. By the way, he is curiously contradictory on subject. I am far from expecting that no cases of apparent impossibility will be found; but certainly I expect that ultimately they will disappear; for instance, Campanulaceae seems a strong case, but now it is pretty clear that they must be liable to crossing. Sweet-peas (583/1. In Lathyrus odoratus the absence of the proper insect has been supposed to prevent crossing. See "Variation under Domestication," Edition II., Volume II., page 68; but the explanation there given for Pisum may probably apply to Lathyrus.), bee-orchis, and perhaps hollyhocks are, at present, my greatest difficulties; and I find I cannot experimentise by castrating sweet-peas, without doing fatal injury. Formerly I felt most interest on this point as one chief means of eliminating varieties; but I feel interest now in other ways. One general fact [that] makes me believe in my doctrine (583/2. The doctrine which has been epitomised as "Nature abhors perpetual self-fertilisation," and is generally known as Knight's Law or the Knight-Darwin Law, is discussed by Francis Darwin in "Nature," 1898. References are there given to the chief passages in the "Origin of Species," etc., bearing on the question. See Letter 19, Volume I.), is that NO terrestrial animal in which semen is liquid is hermaphrodite except with mutual copulation; in terrestrial plants in which the semen is dry there are many hermaphrodites. Indeed, I do wish I lived at Kew, or at least so that I could see you oftener. To return again to subject of crossing: I have been inclined to speculate so far, as to think (my!?) notion (I say MY notion, but I think others have put forward nearly or quite similar ideas) perhaps explains the frequent separation of the sexes in trees, which I think I have heard remarked (and in looking over the mono- and dioecious Linnean classes in Persoon seems true) are very apt to have sexes separated; for [in] a tree having a vast number of flowers on the same individual, or at least the same stock, each flower, if only hermaphrodite on the common plan, would generally get its own pollen or only pollen from another flower on same stock,--whereas if the sexes were separate there would be a better chance of occasional pollen from another distinct stock. I have thought of testing this in your New Zealand Flora, but I have no standard of comparison, and I found myself bothered by bushes. I should propound that some unknown causes had favoured development of trees and bushes in New Zealand, and consequent on this there had been a development of separation of sexes to prevent too much intermarriage. I do not, of course, suppose the prevention of too much intermarriage the only good of separation of sexes. But such wild notions are not worth troubling you with the reading of. LETTER 584. TO J.D. HOOKER. Moor Park [May 2nd, 1857]. The most striking case, which I have stumbled on, on apparent, but false relation of structure of plants to climate, seems to be Meyer and Doege's remark that there is not one single, even moderately-sized, family at the Cape of Good Hope which has not one or several species with heath-like foliage; and when we consider this together with the number of true heaths, any one would have been justified, had it not been for our own British heaths (584/1. It is well known that plants with xerophytic characteristics are not confined to dry climates; it is only necessary to mention halophytes, alpine plants and certain epiphytes. The heaths of Northern Europe are placed among the xerophytes by Warming ("Lehrbuch der okologischen Pflanzengeographie," page 234, Berlin, 1896).), in saying that heath-like foliage must stand in direct relation to a dry and moderately warm climate. Does this not strike you as a good case of false relation? I am so pleased with this place and the people here, that I am greatly tempted to bring Etty here, for she has not, on the whole, derived any benefit from Hastings. With thanks for your never failing assistance to me... I remember that you were surprised at number of seeds germinating in pond mud. I tried a fourth pond, and took about as much mud (rather more than in former case) as would fill a very large breakfast cup, and before I had left home 118 plants had come up; how many more will be up on my return I know not. This bears on chance of birds by their muddy feet transporting fresh-water plants. This would not be a bad dodge for a collector in country when plants were not in seed, to collect and dry mud from ponds. LETTER 585. TO ASA GRAY. Down [1857]. I am very glad to hear that you think of discussing the relative ranges of the identical and allied U. States and European species, when you have time. Now this leads me to make a very audacious remark in opposition to what I imagine Hooker has been writing (585/1. See Letter 338, Volume I.), and to your own scientific conscience. I presume he has been urging you to finish your great "Flora" before you do anything else. Now I would say it is your duty to generalise as far as you safely can from your as yet completed work. Undoubtedly careful discrimination of species is the foundation of all good work; but I must look at such papers as yours in Silliman as the fruit. As careful observation is far harder work than generalisation, and still harder than speculation, do you not think it very possible that it may be overvalued? It ought never to be forgotten that the observer can generalise his own observations incomparably better than any one else. How many astronomers have laboured their whole lives on observations, and have not drawn a single conclusion; I think it is Herschel who has remarked how much better it would be if they had paused in their devoted work and seen what they could have deduced from their work. So do pray look at this side of the question, and let us have another paper or two like the last admirable ones. There, am I not an audacious dog! You ask about my doctrine which led me to expect that trees would tend to have separate sexes. I am inclined to believe that no organic being exists which perpetually self-fertilises itself. This will appear very wild, but I can venture to say that if you were to read my observations on this subject you would agree it is not so wild as it will at first appear to you, from flowers said to be always fertilised in bud, etc. It is a long subject, which I have attended to for eighteen years. Now, it occurred to me that in a large tree with hermaphrodite flowers, we will say it would be ten to one that it would be fertilised by the pollen of its own flower, and a thousand or ten thousand to one that if crossed it would be crossed only with pollen from another flower of same tree, which would be opposed to my doctrine. Therefore, on the great principle of "Nature not lying," I fully expected that trees would be apt to be dioecious or monoecious (which, as pollen has to be carried from flower to flower every time, would favour a cross from another individual of the same species), and so it seems to be in Britain and New Zealand. Nor can the fact be explained by certain families having this structure and chancing to be trees, for the rule seems to hold both in genera and families, as well as in species. I give you full permission to laugh your fill at this wild speculation; and I do not pretend but what it may be chance which, in this case, has led me apparently right. But I repeat that I feel sure that my doctrine has more probability than at first it appears to have. If you had not asked, I should not have written at such length, though I cannot give any of my reasons. The Leguminosae are my greatest opposers: yet if I were to trust to observations on insects made during many years, I should fully expect crosses to take place in them; but I cannot find that our garden varieties ever cross each other. I do NOT ask you to take any trouble about it, but if you should by chance come across any intelligent nurseryman, I wish you would enquire whether they take any pains in raising the varieties of papilionaceous plants apart to prevent crossing. (I have seen a statement of naturally formed crossed Phaseoli near N. York.) The worst is that nurserymen are apt to attribute all varieties to crossing. Finally I incline to believe that every living being requires an occasional cross with a distinct individual; and as trees from the mere multitude of flowers offer an obstacle to this, I suspect this obstacle is counteracted by tendency to have sexes separated. But I have forgotten to say that my maximum difficulty is trees having papilionaceous flowers: some of them, I know, have their keel-petals expanded when ready for fertilisation; but Bentham does not believe that this is general: nevertheless, on principle of nature not lying, I suspect that this will turn out so, or that they are eminently sought by bees dusted with pollen. Again I do NOT ask you to take trouble, but if strolling under your Robinias when in full flower, just look at stamens and pistils whether protruded and whether bees visit them. I must just mention a fact mentioned to me the other day by Sir W. Macarthur, a clever Australian gardener: viz., how odd it was that his Erythrinas in N.S. Wales would not set a seed, without he imitated the movements of the petals which bees cause. Well, as long as you live, you will never, after this fearfully long note, ask me why I believe this or that. LETTER 586. TO ASA GRAY. June 18th [1857]. It has been extremely kind of you telling me about the trees: now with your facts, and those from Britain, N. Zealand, and Tasmania I shall have fair materials for judging. I am writing this away from home, but I think your fraction of 95/132 is as large as in other cases, and is at least a striking coincidence. I thank you much for your remarks about my crossing notions, to which, I may add, I was led by exactly the same idea as yours, viz., that crossing must be one means of eliminating variation, and then I wished to make out how far in animals and vegetables this was possible. Papilionaceous flowers are almost dead floorers to me, and I cannot experimentise, as castration alone often produces sterility. I am surprised at what you say about Compositae and Gramineae. From what I have seen of latter they seemed to me (and I have watched wheat, owing to what L. de Longchamps has said on their fertilisation in bud) favourable for crossing; and from Cassini's observations and Kolreuter's on the adhesive pollen, and C.C. Sprengel's, I had concluded that the Compositae were eminently likely (I am aware of the pistil brushing out pollen) to be crossed. (586/1. This is an instance of the curious ignorance of the essential principles of floral mechanism which was to be found even among learned and accomplished botanists such as Gray, before the publication of the "Fertilisation of Orchids." Even in 1863 we find Darwin explaining the meaning of dichogamy in a letter to Gray.) If in some months' time you can find time to tell me whether you have made any observations on the early fertilisation of plants in these two orders, I should be very glad to hear, as it would save me from great blunder. In several published remarks on this subject in various genera it has seemed to me that the early fertilisation has been inferred from the early shedding of the pollen, which I think is clearly a false inference. Another cause, I should think, of the belief of fertilisation in the bud, is the not-rare, abnormal, early maturity of the pistil as described by Gartner. I have hitherto failed in meeting with detailed accounts of regular and normal impregnation in the bud. Podostemon and Subularia under water (and Leguminosae) seem and are strongest cases against me, as far as I as yet know. I am so sorry that you are so overwhelmed with work; it makes your VERY GREAT kindness to me the more striking. It is really pretty to see how effectual insects are. A short time ago I found a female holly sixty measured yards from any other holly, and I cut off some twigs and took by chance twenty stigmas, cut off their tops, and put them under the microscope: there was pollen on every one, and in profusion on most! weather cloudy and stormy and unfavourable, wind in wrong direction to have brought any. LETTER 587. TO J.D. HOOKER. Down, January 12th [1858]. I want to ask a question which will take you only few words to answer. It bears on my former belief (and Asa Gray strongly expressed opinion) that Papilionaceous flowers were fatal to my notion of there being no eternal hermaphrodites. First let me say how evidence goes. You will remember my facts going to show that kidney-beans require visits of bees to be fertilised. This has been positively stated to be the case with Lathyrus grandiflorus, and has been very partially verified by me. Sir W. Macarthur tells me that Erythrina will hardly seed in Australia without the petals are moved as if by bee. I have just met the statement that, with common bean, when the humble-bees bite holes at the base of the flower, and therefore cease visiting the mouth of the corolla, "hardly a bean will set." But now comes a much more curious statement, that [in] 1842-43, "since bees were established at Wellington (New Zealand), clover seeds all over the settlement, WHICH IT DID NOT BEFORE." (587/1. See Letter 362, Volume I.) The writer evidently has no idea what the connection can be. Now I cannot help at once connecting this statement (and all the foregoing statements in some degree support each other, as all have been advanced without any sort of theory) with the remarkable absence of Papilionaceous plants in N. Zealand. I see in your list Clianthus, Carmichaelia (four species), a new genus, a shrub, and Edwardsia (is latter Papilionaceous?). Now what I want to know is whether any of these have flowers as small as clover; for if they have large flowers they may be visited by humble-bees, which I think I remember do exist in New Zealand; and which humble-bees would not visit the smaller clover. Even the very minute little yellow clover in England has every flower visited and revisited by hive-bees, as I know by experience. Would it not be a curious case of correlation if it could be shown to be probable that herbaceous and small Leguminosae do not exist because when [their] seeds [are] washed ashore (!!!) no small bees exist there. Though this latter fact must be ascertained. I may not prove anything, but does it not seem odd that so many quite independent facts, or rather statements, should point all in one direction, viz., that bees are necessary to the fertilisation of Papilionaceous flowers? LETTER 588. TO JOHN LUBBOCK (Lord Avebury). Sunday [1859]. Do you remember calling my attention to certain flowers in the truss of Pelargoniums not being true, or not having the dark shade on the two upper petals? I believe it was Lady Lubbock's observation. I find, as I expected, it is always the central or sub-central flower; but what is far more curious, the nectary, which is blended with the peduncle of the flowers, gradually lessens and quite disappears (588/1. This fact is mentioned in Maxwell Masters' "Vegetable Teratology" (Ray Society's Publications), 1869, page 221.), as the dark shade on the two upper petals disappears. Compare the stalk in the two enclosed parcels, in each of which there is a perfect flower. Now, if your gardener will not be outrageous, do look over your geraniums and send me a few trusses, if you can find any, having the flowers without the marks, sending me some perfect flowers on same truss. The case seems to me rather a pretty one of correlation of growth; for the calyx also becomes slightly modified in the flowers without marks. LETTER 589. TO MAXWELL MASTERS. Down, April 7th [1860]. I hope that you will excuse the liberty which I take in writing to you and begging a favour. I have been very much interested by the abstract (too brief) of your lecture at the Royal Institution. Many of the facts alluded to are full of interest for me. But on one point I should be infinitely obliged if you could procure me any information: namely, with respect to sweet-peas. I am a great believer in the natural crossing of individuals of the same species. But I have been assured by Mr. Cattell (589/1. The nurseryman he generally dealt with.), of Westerham, that the several varieties of sweet-pea can be raised close together for a number of years without intercrossing. But on the other hand he stated that they go over the beds, and pull up any false plant, which they very naturally attribute to wrong seeds getting mixed in the lot. After many failures, I succeeded in artificially crossing two varieties, and the offspring out of the same pod, instead of being intermediate, was very nearly like the two pure parents; yet in one, there was a trace of the cross, and these crossed peas in the next generation showed still more plainly their mongrel origin. Now, what I want to know is, whether there is much variation in sweet-peas which might be owing to natural crosses. What I should expect would be that they would keep true for many years, but that occasionally, perhaps at long intervals, there would be a considerable amount of crossing of the varieties grown close together. Can you give, or obtain from your father, any information on this head, and allow me to quote your authority? It would really be a very great favour and kindness. LETTER 590. TO J.D. HOOKER. (590/1. The genera Scaevola and Leschenaultia, to which the following letter refers, belong to the Goodeniaceae (Goodenovieae, Bentham & Hooker), an order allied to the Lobeliaceae, although the mechanism of fertilisation resembles rather more nearly that of Campanula. The characteristic feature of the flower in this order is the indusium, or, as Delpino (590/2. Delpino's observations on Dichogamy, summarised by Hildebrand in "Bot. Zeitung," 1870, page 634.) calls it, the "collecting cup": this cuplike organ is a development of the style, and serves the same function as the hairs on the style of Campanula, namely, that of taking the pollen from the anthers and presenting it to the visiting insect. During this stage the immature stigma is at the bottom of the cup, and though surrounded by pollen is incapable of being pollinated. In most genera of the order the pollen is pushed out of the indusium by the growth of the style or stigma, very much as occurs in Lobelia or the Compositae. Finally the style emerges from the indusium (590/3. According to Hamilton ("Proc. Linn. Soc. N. S. Wales," X., 1895, page 361) the stigma rarely grows beyond the indusium in Dampiera. In the same journal (1885-6, page 157, and IX., 1894, page 201) Hamilton has given a number of interesting observations on Goodenia, Scaevola, Selliera, Brunonia. There seem to be mechanisms for cross- and also for self-fertilisation.), the stigmas open out and are pollinated from younger flowers. The mechanism of fertilisation has been described by F. Muller (590/4. In a letter to Hildebrand published in the "Bot. Zeitung," 1868, page 113.), and more completely by Delpino (loc. cit.). Mr. Bentham wrote a paper (590/5. "Linn. Soc. Journal," 1869, page 203.) on the style and stigma in the Goodenovieae, where he speaks of Mr. Darwin's belief that fertilisation takes place outside the indusium. This statement, which we imagine Mr. Bentham must have had from an unpublished source, was incomprehensible to him as long as he confined his work to such genera as Goodenia, Scaevola, Velleia, Coelogyne, in which the mechanism is much as above described; but on examining Leschenaultia the meaning became clear. Bentham writes of this genus:--"The indusium is usually described as broadly two-lipped, without any distinct stigma. The fact appears to be that the upper less prominent lip is stigmatic all over, inside and out, with a transverse band of short glandular hairs at its base outside, while the lower more prominent lip is smooth and glabrous, or with a tuft of rigid hairs. Perhaps this lower lip and the upper band of hairs are all that correspond to the indusium of other genera; and the so-called upper lip, outside of which impregnation may well take place, as observed by Mr. Darwin, must be regarded as the true stigma." Darwin's interest in the Goodeniaceae was due to the mechanism being apparently fitted for self-fertilisation. In 1871 a writer signing himself F.W.B. made a communication to the "Gardeners' Chronicle" (590/6. 1871, page 1103.), in which he expresses himself as "agreeably surprised" to find Leschenaultia adapted for self-fertilisation, or at least for self-pollinisation. This led Darwin to publish a short note in the same journal, in which he describes the penetration of pollen-tubes into the viscid surface on the outside of the indusium. (590/7. 1871, page 1166. He had previously written in the "Journal of Horticulture and Cottage Gardener," May 28th, 1861, page 151:--"Leschenaultia formosa has apparently the most effective contrivance to prevent the stigma of one flower ever receiving a grain of pollen from another flower; for the pollen is shed in the early bud, and is there shut up round the stigma within a cup or indusium. But some observations led me to suspect that nevertheless insect agency here comes into play; for I found by holding a camel-hair pencil parallel to the pistil, and moving it as if it were a bee going to suck the nectar, the straggling hairs of the brush opened the lip of the indusium, entered it, stirred up the pollen, and brought out some grains. I did this to five flowers, and marked them. These five flowers all set pods; whereas only two other pods set on the whole plant, though covered with innumerable flowers...I wrote to Mr. James Drummond, at Swan River in Australia,...and he soon wrote to me that he had seen a bee cleverly opening the indusium and extracting pollen.") He also describes how a brush, pushed into the flower in imitation of an insect, presses "against the slightly projecting lower lip of the indusium, opens it, and some of the hairs enter and become smeared with pollen." The yield of pollen is therefore differently arranged in Leschenaultia; for in the more typical genera it depends on the growth of the style inside the indusium. Delpino, however (see Hildebrand's version, loc. cit.), describes a similar opening of the cup produced by pressure on the hairs in some genera of the order.) Down, June 7th [1860]. Best and most beloved of men, I supplicate and entreat you to observe one point for me. Remember that the Goodeniaceae have weighed like an incubus for years on my soul. It relates to Scaevola microcarpa. I find that in bud the indusium collects all the pollen splendidly, but, differently from Leschenaultia, cannot be afterwards easily opened. Further, I find that at an early stage, when the flower first opens, a boat-shaped stigma lies at the bottom of the indusium, and further that this stigma, after the flower has some time expanded, grows very rapidly, when the plant is kept hot, and pushes out of the indusium a mass of pollen; and at same time two horns project at the corners of the indusium. Now the appearance of these horns makes me suppose that these are the stigmatic surfaces. Will you look to this? for if they be by the relative position of the parts (with indusium and stigma bent at right angles to style) [I am led to think] that an insect entering a flower could not fail to have [its] whole back (at the period when, as I have seen, a whole mass of pollen is pushed out) covered with pollen, which would almost certainly get rubbed on the two horns. Indeed, I doubt whether, without this aid, pollen would get on to the horns. What interests me in the case is the analogy in result with the Lobelia, but by very different means. In Lobelia the stigma, before it is mature, pushes by its circular brush of hairs the pollen out of the conjoined anthers; here the indusium collects pollen, and then the growth of the stigma pushes it out. In the course of about 1 1/2 hour, I found an indusium with hairs on the outer edge perfectly clogged with pollen, and horns protruded, which before the 1 1/2 hour had not one grain of pollen outside the indusium, and no trace of protruding horns. So you will see how I wish to know whether the horns are the true stigmatic surfaces. I would try the case experimentally by putting pollen on the horns, but my greenhouse is so cold, and my plant so small, and in such a little pot, that I suppose it would not seed... The little length of stigmatic horns at the moment when pollen is forced out of the indusium, compared to what they ultimately attain, makes me fancy that they are not then mature or ready, and if so, as in Lobelia, each flower must be fertilised by pollen from another and earlier flower. How curious that the indusium should first so cleverly collect pollen and then afterwards push it out! Yet how closely analogous to Campanula brushing pollen out of the anther and retaining it on hairs till the stigma is ready. I am going to try whether Campanula sets seed without insect agency. LETTER 591. TO J.D. HOOKER. (591/1. The following letters are given here rather than in chronological order, as bearing on the Leschenaultia problem. The latter part of Letter 591 refers to the cleistogamic flowers of Viola.) Down, May 1st [1862]. If you can screw out time, do look at the stigma of the blue Leschenaultia biloba. I have just examined a large bud with the indusium not yet closed, and it seems to me certain that there is no stigma within. The case would be very important for me, and I do not like to trust solely to myself. I have been impregnating flowers, but it is rather difficult... I have just looked again at Viola canina. The case is odder: only 2 stamens which embrace the stigma have pollen; the 3 other stamens have no anther-cells and no pollen. These 2 fertile anthers are of different shape from the 3 sterile others, and the scale representing the lower lip is larger and differently shaped from the 4 other scales representing 4 other petals. In V. odorata (single flower) all five stamens produce pollen. But I daresay all this is known. LETTER 592. TO J.D. HOOKER. November 3rd [1862]. Do you remember the scarlet Leschenaultia formosa with the sticky margin outside the indusium? Well, this is the stigma--at least, I find the pollen-tubes here penetrate and nowhere else. What a joke it would be if the stigma is always exterior, and this by far the greatest difficulty in my crossing notions should turn out a case eminently requiring insect aid, and consequently almost inevitably ensuring crossing. By the way, have you any other Goodeniaceae which you could lend me, besides Leschenaultia and Scaevola, of which I have seen enough? I had a long letter the other day from Crocker of Chichester; he has the real spirit of an experimentalist, but has not done much this summer. LETTER 593. TO F. MULLER. Down, April 9th and 15th [1866]. I am very much obliged by your letter of February 13th, abounding with so many highly interesting facts. Your account of the Rubiaceous plant is one of the most extraordinary that I have ever read, and I am glad you are going to publish it. I have long wished some one to observe the fertilisation of Scaevola, and you must permit me to tell you what I have observed. First, for the allied genus of Leschenaultia: utterly disbelieving that it fertilises itself, I introduced a camel-hair brush into the flower in the same way as a bee would enter, and I found that the flowers were thus fertilised, which never otherwise happens; I then searched for the stigma, and found it outside the indusium with the pollen-tubes penetrating it; and I convinced Dr. Hooker that botanists were quite wrong in supposing that the stigma lay inside the indusium. In Scaevola microcarpa the structure is very different, for the immature stigma lies at the base within the indusium, and as the stigma grows it pushes the pollen out of the indusium, and it then clings to the hairs which fringe the tips of the indusium; and when an insect enters the flower, the pollen (as I have seen) is swept from these long hairs on to the insect's back. The stigma continues to grow, but is not apparently ready for impregnation until it is developed into two long protruding horns, at which period all the pollen has been pushed out of the indusium. But my observations are here at fault, for I did not observe the penetration of the pollen-tubes. The case is almost parallel with that of Lobelia. Now, I hope you will get two plants of Scaevola, and protect one from insects, leaving the other uncovered, and observe the results, both in the number of capsules produced, and in the average number of seeds in each. It would be well to fertilise half a dozen flowers under the net, to prove that the cover is not injurious to fertility. With respect to your case of Aristolochia, I think further observation would convince you that it is not fertilised only by larvae, for in a nearly parallel case of an Arum and a Aristolochia, I found that insects flew from flower to flower. I would suggest to you to observe any cases of flowers which catch insects by their probosces, as occurs with some of the Apocyneae (593/1. Probably Asclepiadeae. See H. Muller, "Fertilisation of Flowers," page 396.); I have never been able to conceive for what purpose (if any) this is effected; at the same time, if I tempt you to neglect your zoological work for these miscellaneous observations I shall be guilty of a great crime. To return for a moment to the indusium: how curious it is that the pollen should be thus collected in a special receptacle, afterwards to be swept out by insects' agency! I am surprised at what you tell me about the fewness of the flowers of your native orchids which produce seed-capsules. What a contrast with our temperate European species, with the exception of some species of Ophrys!--I now know of three or four cases of self-fertilising orchids, but all these are provided with means for an occasional cross. I am sorry to say Dr. Cruger is dead from a fever. I received yesterday your paper in the "Botanische Zeitung" on the wood of climbing plants. (593/2. Fritz Muller, "Ueber das Holz einiger um Desterro wachsenden Kletterpflanzen." "Botanische Zeitung," 1866, pages 57, 65.) I have read as yet only your very interesting and curious remarks on the subject as bearing on the change of species; you have pleased me by the very high compliments which you pay to my paper. I have been at work since March 1st on a new English edition (593/3. The 4th Edition.) of my "Origin," of which when published I will send you a copy. I have much regretted the time it has cost me, as it has stopped my other work. On the other hand, it will be useful for a new third German edition, which is now wanted. I have corrected it largely, and added some discussions, but not nearly so much as I wished to do, for, being able to work only two hours daily, I feared I should never get it finished. I have taken some facts and views from your work "Fur Darwin"; but not one quarter of what I should like to have quoted. LETTER 594. TO A.G. MORE. Down, June 24th, 1860. I hope that you will forgive the liberty which I take in writing to you and requesting a favour. Mr. H.C. Watson has given me your address, and has told me that he thought that you would be willing to oblige me. Will you please to read the enclosed, and then you will understand what I wish observed with respect to the bee-orchis. (594/1. Ophrys apifera.) What I especially wish, from information which I have received since publishing the enclosed, is that the state of the pollen-masses should be noted in flowers just beginning to wither, in a district where the bee-orchis is extremely common. I have been assured that in parts of Isle of Wight, viz., Freshwater Gate, numbers occur almost crowded together: whether anything of this kind occurs in your vicinity I know not; but, if in your power, I should be infinitely obliged for any information. As I am writing, I will venture to mention another wish which I have: namely, to examine fresh flowers and buds of the Aceras, Spiranthes, marsh Epipactis, and any other rare orchis. The point which I wish to examine is really very curious, but it would take too long space to explain. Could you oblige me by taking the great trouble to send me in an old tin canister any of these orchids, permitting me, of course, to repay postage? It would be a great kindness, but perhaps I am unreasonable to make such a request. If you will inform me whether you have leisure so far to oblige me, I would tell you my movements, for on account of my own health and that of my daughter, I shall be on the move for the next two or three weeks. I am sure I have much cause to apologise for the liberty which I have taken... LETTER 595. TO A.G. MORE. Down, August 3rd, 1860. I thank you most sincerely for sending me the Epipactis [palustris]. You can hardly imagine what an interesting morning's work you have given me, as the rostellum exhibited a quite new modification of structure. It has been extremely kind of you to take so very much trouble for me. Have you looked at the pollen-masses of the bee-Ophrys? I do not know whether the Epipactis grows near to your house: if it does, and any object takes you to the place (pray do not for a moment think me so very unreasonable as to ask you to go on purpose), would you be so kind [as] to watch the flowers for a quarter of an hour, and mark whether any insects (and what?) visit these flowers. I should suppose they would crawl in by depressing the terminal portion of the labellum; and that when within the flower this terminal portion would resume its former position; and lastly, that the insect in crawling out would not depress the labellum, but would crawl out at back of flower. (595/1. The observations of Mr. William Darwin on Epipactis palustris given in the "Fertilisation of Orchids," Edition II., 1877, page 99, bear on this point. The chief fertilisers are hive-bees, which are too big to crawl into the flower. They cling to the labellum, and by depressing it open up the entrance to the flower. Owing to the elasticity of the labellum and its consequent tendency to spring up when released, the bees, "as they left the flower, seemed to fly rather upwards." This agrees with Darwin's conception of the mechanism of the flower as given in the first edition of the Orchid book, 1862, page 100, although at that time he imagined that the fertilising insect crawled into the flower. The extreme flexibility and elasticity of the labellum was first observed by Mr. More (see first edition, page 99). The description of the flower given in the above letter to Mr. More is not quite clear; the reader is referred to the "Fertilisation of Orchids," loc. cit.) An insect crawling out of a recently opened flower would, I believe, have parts of the pollen-masses adhering to the back or shoulder. I have seen this in Listera. How I should like to watch the Epipactis. If you can it any time send me Spiranthes or Aceras or O. ustulata, you would complete your work of kindness. P.S.--If you should visit the Epipactis again, would you gather a few of the lower flowers which have been opened for some time and have begun to wither a little, and observe whether pollen is well cleared out of anther-case. I have been struck with surprise that in nearly all the lower flowers sent by you, though much of the pollen has been removed, yet a good deal of pollen is left wasted within the anthers. I observed something of this kind in Cephalanthera grandiflora. But I fear that you will think me an intolerable bore. LETTER 596. TO A.G. MORE. Down, August 5th, 1860. I am infinitely obliged for your most clearly stated observations on the bee-orchis. It is now perfectly clear that something removes the pollen-masses far more with you than in this neighbourhood. But I am utterly puzzled about the foot-stalk being so often cut through. I should suspect snails. I yesterday found thirty-nine flowers, and of them only one pollen-mass in three flowers had been removed, and as these were extremely much-withered flowers I am not quite sure of the truth of this. The wind again is a new element of doubt. Your observations will aid me extremely in coming to some conclusion. (596/1. Mr. More's observations on the percentage of flowers in which the pollinia were absent are quoted in "Fertilisation of Orchids," Edition I., page 68.) I hope in a day or two to receive some day-moths, on the probosces of which I am assured the pollen-masses of the bee-orchis still adhere (596/2. He was doomed to disappointment. On July 17th, 1861, he wrote to Mr. More:--"I found the other day a lot of bee-Ophrys with the glands of the pollinia all in their pouches. All facts point clearly to eternal self-fertilisation in this species; yet I cannot swallow the bitter pill. Have you looked at any this year?")... I wrote yesterday to thank you for the Epipactis. For the chance of your liking to look at what I have found: take a recently opened flower, drag gently up the stigmatic surface almost any object (the side of a hooked needle), and you will find the cap of the hemispherical rostellum comes off with a touch, and being viscid on under-surface, clings to needle, and as pollen-masses are already attached to the back of rostellum, the needle drags out much pollen. But to do this, the curiously projecting and fleshy summits of anther-cases must at some time be pushed back slightly. Now when an insect's head gets into the flower, when the flap of the labellum has closed by its elasticity, the insect would naturally creep out by the back-side of the flower. And mark when the insect flies to another flower with the pollen-masses adhering to it, if the flap of labellum did not easily open and allow free ingress to the insect, it would surely rub off the pollen on the upper petals, and so not leave it on stigma. It is to know whether I have rightly interpreted the structure of this whole flower that I am so curious to see how insects act. Small insects, I daresay, would crawl in and out and do nothing. I hope that I shall not have wearied you with these details. If you would like to see a pretty and curious little sight, look to Orchis pyramidalis, and you will see that the sticky glands are congenitally united into a saddle-shaped organ. Remove this under microscope by pincers applied to foot-stalk of pollen-mass, and look quickly at the spontaneous movement of the saddle-shaped organs and see how beautifully adapted to seize proboscis of moth. LETTER 597. TO J.D. HOOKER December 4th [1860]. Many thanks about Apocynum and Meyen. The latter I want about some strange movements in cells of Drosera, which Meyen alone seems to have observed. (597/1. No observations of Meyen are mentioned in "Insectivorous Plants.") It is very curious, but Trecul disbelieves that Drosera really clasps flies! I should very much wish to talk over Drosera with you. I did chloroform it, and the leaves which were already expanded did not recover thirty seconds of exposure for three days. I used the expression weight for the bit of hair which caused movement and weighed 1/78000 of a grain; but I do not believe it is weight, and what it is, I cannot after many experiments conjecture. (597/2. The doubt here expressed as to whether the result is due to actual weight is interesting in connection with Pfeffer's remarkable discovery that a smooth object in contact with the gland produces no effect if the plant is protected from all vibration; on an ordinary table the slight shaking which reaches the plant is sufficient to make the body resting on the gland tremble, and thus produce a series of varying pressures--under these circumstances the gland is irritated, and the tentacle moves. See Pfeffer, "Untersuchungen aus d. bot. Institut zu Tubingen," Volume I., 1885, page 483; also "Insectivorous Plants," Edition II., page 22.) The movement in this case does not depend on the chemical nature of substance. Latterly I have tried experiments on single glands, and a microscopical atom of raw meat causes such rapid movement that I could see it move like hand of clock. In this case it is the nature of the object. It is wonderful the rapidity of the absorption: in ten seconds weak solution of carbonate of ammonia changes not the colour, but the state of contents within the glands. In two minutes thirty seconds juice of meat has been absorbed by gland and passed from cell to cell all down the pedicel (or hair) of the gland, and caused the sap to pass from the cells on the upper side of the pedicel to the lower side, and this causes the curvature of the pedicel. I shall work away next summer when Drosera opens again, for I am much interested in subject. After the glandular hairs have curved, the oddest changes take place--viz., a segregation of the homogeneous pink fluid and necessary slow movements in the thicker matter. By Jove, I sometimes think Drosera is a disguised animal! You know that I always so like telling you what I do, that you must forgive me scribbling on my beloved Drosera. Farewell. I am so very glad that you are going to reform your ways; I am sure that you would have injured your health seriously. There is poor Dana has done actually nothing--cannot even write a letter--for a year, and it is hoped that in another YEAR he may quite recover. After this homily, good night, my dear friend. Good heavens, I ought not to scold you, but thank you, for writing so long and interesting a letter. LETTER 598. TO E. CRESY. Down, December 12th [1860?]. After writing out the greater part of my paper on Drosera, I thought of so many points to try, and I wished to re-test the basis of one large set of experiments, namely, to feel still more sure than I am, that a drop of plain water never produces any effect, that I have resolved to publish nothing this year. For I found in the record of my daily experiments one suspicious case. I must wait till next summer. It will be difficult to try any solid substances containing nitrogen, such as ivory; for two quite distinct causes excite the movement, namely, mechanical irritation and presence of nitrogen. When a solid substance is placed on leaf it becomes clasped, but is released sooner than when a nitrogenous solid is clasped; yet it is difficult (except with raw meat and flies) to be sure of the result, owing to differences in vigour of different plants. The last experiments which I tried before my plants became too languid are very curious, and were tried by putting microscopical atoms on the gland itself of single hairs; and it is perfectly evident that an atom of human hair, 1/76000 of a grain (as ascertained by weighing a length of hair) in weight, causes conspicuous movement. I do not believe (for atoms of cotton thread acted) it is the chemical nature; and some reasons make me doubt whether it is actual weight; it is not the shadow; and I am at present, after many experiments, confounded to know what the cause is. That these atoms did really act and alter the state of the contents of all the cells in the glandular hair, which moved, was perfectly clear. But I hope next summer to make out a good deal more... LETTER 599. TO J.D. HOOKER. Down, May 14th [1861]. I have been putting off writing from day to day, as I did not wish to trouble you, till my wish for a little news will not let me rest... I have no news to tell you, for I have had no interesting letters for some time, and have not seen a soul. I have been going through the "Cottage Gardener" of last year, on account chiefly of Beaton's articles (599/1. Beaton was a regular contributor to the "Cottage Gardener," and wrote various articles on cross breeding, etc., in 1861. One of these was in reply to a letter published in the "Cottage Gardener," May 14th, 1861, page 112, in which Darwin asked for information as to the Compositae and the hollyhock being crossed by insect visitors. In the number for June 8th, 1861, page 211, Darwin wrote on the variability of the central flower of the carrot and the peloria of the central flower in Pelargonium. An extract from a letter by Darwin on Leschenaultia, "Cottage Gardener," May 28th, 1861, page 151, is given in Letter 590, note.); he strikes me as a clever but d--d cock-sure man (as Lord Melbourne said), and I have some doubts whether to be much trusted. I suspect he has never recorded his experiment at the time with care. He has made me indignant by the way he speaks of Gartner, evidently knowing nothing of his work. I mean to try and pump him in the "Cottage Gardener," and shall perhaps defend Gartner. He alludes to me occasionally, and I cannot tell with what spirit. He speaks of "this Mr. Darwin" in one place as if I were a very noxious animal. Let me have a line about poor Henslow pretty soon. (599/2. In a letter of May 18th, 1861, Darwin wrote again:--) By the way, thanks about Beaton. I have now read more of his writings, and one answer to me in "Cottage Gardener." I can plainly see that he is not to be trusted. He does not well know his own subject of crossing. LETTER 600. TO J.D. HOOKER. (600/1. Part of this letter has been published in "Life and Letters," III., page 265.) 2, Hesketh Crescent, Torquay [1861]. ...The beauty of the adaptation of parts seems to me unparalleled. I should think or guess [that] waxy pollen was most differentiated. In Cypripedium, which seems least modified, and a much exterminated group, the grains are single. In all others, as far as I have seen, they are in packets of four; and these packets cohere into many wedge-formed masses in Orchis, into eight, four, and finally two. It seems curious that a flower should exist which could, at most, fertilise only two other flowers, seeing how abundant pollen generally is; this fact I look at as explaining the perfection of the contrivance by which the pollen, so important from its fewness, is carried from flower to flower. By the way, Cephalanthera has single pollen-grains, but this seems to be a case of degradation, for the rostellum is utterly aborted. Oddly, the columns of pollen are here kept in place by very early penetration of pollen-tubes into the edge of the stigma; nevertheless, it receives more pollen by insect agency. Epithecia [Dichaea] has done me one good little turn. I often speculated how the caudicle of Orchis had been formed. (600/2. The gradation here suggested is thoroughly worked out in the "Fertilisation of Orchids," Edition I., page 323, Edition II., page 257.) I had noticed slight clouds in the substance half way down; I have now dissected them out, and I find they are pollen-grains fairly embedded and useless. If you suppose the pollen-grains to abort in the lower half of the pollinia of Epipactis, but the parallel elastic threads to remain and cohere, you have the caudicle of Orchis, and can understand the few embedded and functionless pollen-grains. I must not look at any more exotic orchids: hearty thanks for your offer. But if you would make one single observation for me on Cypripedium, I should be glad. Asa Gray writes to me that the outside of the pollen-masses is sticky in this genus; I find that the whole mass consists of pollen-grains immersed in a sticky brownish thick fluid. You could tell by a mere lens and penknife. If it is, as I find it, pollen could not get on the stigma without insect aid. Cypripedium confounds me much. I conjecture that drops of nectar are secreted by the surface of the labellum beneath the anthers and in front of the stigma, and that the shield over the anthers and the form of labellum is to compel insects to insert their proboscis all round both organs. (600/3. This view was afterwards given up.) It would be troublesome for you to look at this, as it is always bothersome to catch the nectar secreting, and the cup of the labellum gets filled with water by gardener's watering. I have examined Listera ovata, cordata, and Neottia nidus avis: the pollen is uniform; I suspect you must have seen some observation founded on a mistake from the penetration and hardening of sticky fluid from the rostellum, which does penetrate the pollen a little. It is mere virtue which makes me not wish to examine more orchids; for I like it far better than writing about varieties of cocks and hens and ducks. Nevertheless, I have just been looking at Lindley's list in the "Vegetable Kingdom," and I cannot resist one or two of his great division of Arethuseae, which includes Vanilla. And as I know so well the Ophreae, I should like (God forgive me) any one of the Satyriadae, Disidae and Corycidae. I fear my long lucubrations will have wearied you, but it has amused me to write, so forgive me. LETTER 601. TO J.D. HOOKER. (601/1. Part of the following letter is published in the "Life and Letters," the remainder, with the omission of part bearing on the Glen Roy problem, is now given as an example of the varied botanical assistance Darwin received from Sir Joseph Hooker. For the part relating to Verbascum see the "Variation of Animals and Plants," Edition II., 1875, Volume II., page 83. The point is that the white and yellow flowered plants which occur in two species of Verbascum are undoubted varieties, yet "the sterility which results from the crossing of the differently coloured varieties of the same species is fully as great as that which occurs in many cases when distinct species are crossed." The sterility of the long-styled form (B) of Linum grandiflorum, with its own pollen is described in "Forms of Flowers," Edition II., page 87: his conclusions on the short-styled form (A) differ from those in the present letter.) September 28th [1861]. I am going to beg for help, and I will explain why I want it. You offer Cypripedium; I should be very glad of a specimen, and of any good-sized Vandeae, or indeed any orchids, for this reason: I never thought of publishing separately, and therefore did not keep specimens in spirits, and now I should be very glad of a few woodcuts to illustrate my few remarks on exotic orchids. If you can send me any, send them by post in a tin canister on middle of day of Saturday, October 5th, for Sowerby will be here. Secondly: Have you any white and yellow varieties of Verbascum which you could give me, or propagate for me, or LEND me for a year? I have resolved to try Gartner's wonderful and repeated statement, that pollen of white and yellow varieties, whether used on the varieties or on DISTINCT species, has different potency. I do not think any experiment can be more important on the origin of species; for if he is correct we certainly have what Huxley calls new physiological species arising. I should require several species of Verbascum besides the white and yellow varieties of the same species. It will be tiresome work, but if I can anyhow get the plants, it shall be tried. Thirdly: Can you give me seeds of any Rubiaceae of the sub-order Cinchoneae, as Spermacoce, Diodia, Mitchella, Oldenlandia? Asa Gray says they present two forms like Primula. I am sure that this subject is well worth working out. I have just almost proved a very curious case in Linum grandiflorum which presents two forms, A and B. Pollen of A is perfectly fertile on stigma of A. But pollen of B is absolutely barren on its own stigma; you might as well put so much flour on it. It astounded me to see the stigmas of B purple with its own pollen; and then put a few grains of similar-looking pollen of A on them, and the germen immediately and always swelled; those not thus treated never swelling. Fourthly: Can you give me any very hairy Saxifraga (for their functions) [i.e. the functions of the hairs]? I send you a resume of my requests, to save you trouble. Nor would I ask for so much aid if I did not think all these points well worth trying to investigate. My dear old friend, a letter from you always does me a world of good. And, the Lord have mercy on me, what a return I make. LETTER 602. TO J.D. HOOKER. Down, October 4th [1861]. Will you have the kindness to read the enclosed, and look at the diagram. Six words will answer my question. It is not an important point, but there is to me an irresistible charm in trying to make out homologies. (602/1. In 1880 he wrote to Mr. Bentham: "It was very kind of you to write to me about the Orchideae, for it has pleased me to an extreme degree that I could have been of the least use to you about the nature of the parts."--"Life and Letters," III., page 264.) You know the membranous cup or clinandrum, in many orchids, behind the stigma and rostellum: it is formed of a membrane which unites the filament of the normal dorsal anther with the edges of the pistil. The clinandrum is largely developed in Malaxis, and is of considerable importance in retaining the pollinia, which as soon as the flower opens are quite loose. The appearance and similarity of the tissues, etc., at once gives suspicion that the lateral membranes of the clinandrum are the two other and rudimentary anthers, which in Orchis and Cephalanthera, etc., exist as mere papillae, here developed and utilised. Now for my question. Exactly in the middle of the filament of the normal anther, and exactly in the middle of the lateral membrane of the clinandrum, and running up to the same height, are quite similar bundles of spiral vessels; ending upwards almost suddenly. Now is not this structure a good argument that I interpret the homologies of the sides of clinandrum rightly? (602/2. Though Robert Brown made use of the spiral vessels of orchids, yet according to Eichler, "Bluthendiagramme," 1875, Volume I., page 184, Darwin was the first to make substantial additions to the conclusions deducible from the course of the vessels in relation to the problem of the morphology of these plants. Eichler gives Darwin's diagram side by side with that of Van Tieghem without attempting to decide between the differences in detail by which they are characterised.) I find that the great Bauer does not draw very correctly! (602/3. F. Bauer, whom Pritzel calls "der grosste Pflanzenmaler." The reference is to his "Illustrations of Orchidaceous Plants, with Notes and Prefatory Remarks by John Lindley," London, 1830-38, Folio. See "Fertilisation of Orchids," Edition II., page 82.) And, good Heavens, what a jumble he makes on functions. LETTER 603. TO J.D. HOOKER. Down, October 22nd. [1861]. Acropera is a beast,--stigma does not open, everything seems contrived that it shall NOT be anyhow fertilised. There is something very odd about it, which could only be made out by incessant watching on several individual plants. I never saw the very curious flower of Canna; I should say the pollen was deposited where it is to prevent inevitable self-fertilisation. You have no time to try the smallest experiment, else it would be worth while to put pollen on some stigmas (supposing that it does not seed freely with you). Anyhow, insects would probably carry pollen from flower to flower, for Kurr states the tube formed by pistil, stamen and "nectarblatt" secretes (I presume internally) much nectar. Thanks for sending me the curious flower. Now I want much some wisdom; though I must write at considerable length, your answer may be very brief. (FIGURE 8.--FLORAL DIAGRAM OF AN ORCHID. The "missing bundle" could not be found in some species.) In R. Brown's admirable paper in the "Linnean Transacts." (603/4. Volume XVI., page 685.) he suggests (and Lindley cautiously agrees) that the flower of orchids consists of five whorls, the inner whorl of the two whorls of anthers being all rudimentary, and when the labellum presents ridges, two or three of the anthers of both whorls [are] combined with it. In the ovarium there are six bundles of vessels: R. Brown judged by transverse sections. It occurred to me, after what you said, to trace the vessels longitudinally, and I have succeeded well. Look at my diagram [Figure 8] (which please return, for I am transported with admiration at it), which shows the vessels which I have traced, one bundle to each of fifteen theoretical organs, and no more. You will see the result is nothing new, but it seems to confirm strongly R. Brown, for I have succeeded (perhaps he did, but he does not say so) in tracing the vessels belonging to each organ in front of each other to the same bundle in the ovarium: thus the vessels going to the lower sepal, to the side of the labellum, and to one stigma (when there are two) all distinctly branch from one ovarian bundle. So in other cases, but I have not completely traced (only seen) that going to the rostellum. But here comes my only point of novelty: in all orchids as yet looked at (even one with so simple a labellum as Gymnadenia and Malaxis) the vessels on the two sides of the labellum are derived from the bundle which goes to the lower sepal, as in the diagram. This leads me to conclude that the labellum is always a compound organ. Now I want to know whether it is conceivable that the vessels coming from one main bundle should penetrate an organ (the labellum) which receives its vessels from another main bundle? Does it not imply that all that part of the labellum which is supplied by vessels coming from a lateral bundle must be part of a primordially distinct organ, however closely the two may have become united? It is curious in Gymnadenia to trace the middle anterior bundle in the ovarium: when it comes to the orifice of the nectary it turns and runs right down it, then comes up the opposite side and runs to the apex of the labellum, whence each side of the nectary is supplied by vessels from the bundles, coming from the lower sepals. Hence even the thin nectary is essentially, I infer, tripartite; hence its tendency to bifurcation at its top. This view of the labellum always consisting of three organs (I believe four when thick, as in Mormodes, at base) seems to me to explain its great size and tripartite form, compared with the other petals. Certainly, if I may trust the vessels, the simple labellum of Gymnadenia consists of three organs soldered together. Forgive me for writing at such length; a very brief answer will suffice. I am desperately interested in the subject: the destiny of the whole human race is as nothing to the course of vessels of orchids... What plant has the most complex single stigma and pistil? The most complex I, in my ignorance, can think of is in Iris. I want to know whether anything beats in modification the rostellum of Catasetum. To-morrow I mean to be at Catasetum. Hurrah! What species is it? It is wonderfully different from that which Veitch sent me, which was C. saccatum. According to the vessels, an orchid flower consists of three sepals and two petals free; and of a compound organ (its labellum), consisting of one petal and of two (or three) modified anthers; and of a second compound body consisting of three pistils, one normal anther, and two modified anthers often forming the sides of the clinandrum. LETTER 604. TO JOHN LINDLEY. (604/1. It was in the autumn of 1861 that Darwin made up his mind to publish his Orchid work as a book, rather than as a paper in the Linnean Society's "Journal." (604/2. See "Life and Letters," III., page 266.) The following letter shows that the new arrangement served as an incitement to fresh work.) Down, October 25th [1861?] Mr. James Veitch has been most generous. I did not know that you had spoken to him. If you see him pray say I am truly grateful; I dare not write to a live Bishop or a Lady, but if I knew the address of "Rucker"? and might use your name as introduction, I might write. I am half mad on the subject. Hooker has sent me many exotics, but I stopped him, for I thought I should make a fool of myself; but since I have determined to publish I much regret it. (FIGURE 9.--HABENARIA CHLORANTHA (Longitudinal course of bundles).) (605/1. The three upper curved outlines, two of which passing through the words "upper sepal," "upper petal," "lower sepal," were in red in the original; for explanation see text.) LETTER 605. TO J.D. HOOKER. (605/2. The following letter is of interest because it relates to one of the two chief difficulties Darwin met with in working out the morphology of the orchid flower. In the orchid book (605/3. Edition I., page 303.) he wrote, "This anomaly [in Habenaria] is so far of importance, as it throws some doubt on the view which I have taken of the labellum being always an organ compounded of one petal and two petaloid stamens." That is to say, it leaves it open for a critic to assert that the vessels which enter the sides of the labellum are lateral vessels of the petal and do not necessarily represent petaloid stamens. In the sequel he gives a satisfactory answer to the supposed objector.) Down, November 10th, [1861]. For the love of God help me. I believe all my work (about a fortnight) is useless. Look at this accursed diagram (Figure 9) of the butterfly-orchis [Habenaria], which I examined after writing to you yesterday, when I thought all my work done. Some of the ducts of the upper sepal (605/4. These would be described by modern morphologists as lower, not upper, sepals, etc. Darwin was aware that he used these terms incorrectly.) and upper petal run to the wrong bundles on the column. I have seen no such case. This case apparently shows that not the least reliance can be placed on the course of ducts. I am sure of my facts. There is great adhesion and extreme displacement of parts where the organs spring from the top of the ovarium. Asa Gray says ducts are very early developed, and it seems to me wonderful that they should pursue this course. It may be said that the lateral ducts in the labellum running into the antero-lateral ovarian bundle is no argument that the labellum consists of three organs blended together. In desperation (and from the curious way the base of upper petals are soldered at basal edges) I fancied the real form of upper sepal, upper petal and lower sepal might be as represented by red lines, and that there had been an incredible amount of splitting of sepals and petals and subsequent fusion. This seems a monstrous notion, but I have just looked at Bauer's drawing of allied Bonatea, and there is a degree of lobing of petals and sepals which would account for anything. Now could you spare me a dry flower out of your Herbarium of Bonatea speciosa (605/5. See "Fertilisation of Orchids," Edition I., page 304 (note), where the resemblances between the anomalous vessels of Bonatea and Habenaria are described. On November 14th, 1861, he wrote to Sir Joseph: "You are a true friend in need. I can hardly bear to let the Bonatea soak long enough."), that I might soak and look for ducts. If I cannot explain the case of Habenaria all my work is smashed. I was a fool ever to touch orchids. LETTER 606. TO J.D. HOOKER. Down, November 17th [1861]. What two very interesting and useful letters you have sent me. You rather astound me with respect to value of grounds of generalisation in the morphology of plants. It reminds me that years ago I sent you a grass to name, and your answer was, "It is certainly Festuca (so-and-so), but it agrees as badly with the description as most plants do." I have often laughed over this answer of a great botanist...Lindley, from whom I asked for an orchid with a simple labellum, has most kindly sent me a lot of what he marks "rare" and "rarissima" of peloric orchids, etc., but as they are dried I know not whether they will be of use. He has been most kind, and has suggested my writing to Lady D. Nevill, who has responded in a wonderfully kind manner, and has sent a lot of treasures. But I must stop; otherwise, by Jove, I shall be transformed into a botanist. I wish I had been one; this morphology is surprisingly interesting. Looking to your note, I may add that certainly the fifteen alternating bundles of spiral vessels (mingled with odd beadlike vessels in some cases) are present in many orchids. The inner whorl of anther ducts are oftenest aborted. I must keep clear of Apostasia, though I have cast many a longing look at it in Bauer. (606/1. Apostasia has two fertile anthers like Cypripedium. It is placed by Engler and Prantl in the Apostasieae or Apostasiinae, among the Orchideae, by others in a distinct but closely allied group.) I hope I may be well enough to read my own paper on Thursday, but I have been very seedy lately. (606/2. "On the two Forms, or Dimorphic Condition, in the Species of the Genus Primula," "Linn. Soc. Journ." 1862. He did read the paper, but it cost him the next day in bed. "Life and Letters," III., page 299.) I see there is a paper at the Royal on the same night, which will more concern you, on fossil plants of Bovey (606/3. Oswald Heer, "The Fossil Flora of Bovey Tracey," "Phil. Trans. R. Soc." 1862, page 1039.), so that I suppose I shall not have you; but you must read my paper when published, as I shall very much like to hear what you think. It seems to me a large field for experiment. I shall make use of my Orchid little volume in illustrating modification of species doctrine, but I keep very, very doubtful whether I am not doing a foolish action in publishing. How I wish you would keep to your old intention and write a book on plants. (606/4. Possibly a book similar to that described in Letter 696.) LETTER 607. TO G. BENTHAM. Down, November 26th [1861]. Our notes have crossed on the road. I know it is an honour to have a paper in the "Transactions," and I am much obliged to you for proposing it, but I should greatly prefer to publish in the "Journal." Nor does this apply exclusively to myself, for in old days at the Geological Society I always protested against an abstract appearing when the paper itself might appear. I abominate also the waste of time (and it would take me a day) in making an abstract. If the referee on my paper should recommend it to appear in the "Transactions," will you be so kind as to lay my earnest request before the Council that it may be permitted to appear in the "Journal?" You must be very busy with your change of residence; but when you are settled and have some leisure, perhaps you will be so kind as to give me some cases of dimorphism, like that of Primula. Should you object to my adding them to those given me by A. Gray? By the way, I heard from A. Gray this morning, and he gives me two very curious cases in Boragineae. LETTER 608. TO JOHN LINDLEY. (608/1. In the following fragment occurs the earliest mention of Darwin's work on the three sexual forms of Catasetum tridentatum. Sir R. Schomburgk (608/2. "Trans. Linn. Soc." XVII., page 522.) described Catasetum tridentatum, Monacanthus viridis and Myanthus barbatus occurring on a single plant, but it remained for Darwin to make out that they are the male, female and hermaphrodite forms of a single species. (608/3. "Fertilisation of Orchids," Edition I., page 236; Edition II., page 196.) With regard to the species of Acropera (Gongora) (608/4. Acropera Loddigesii = Gongora galeata: A. luteola = G. fusca ("Index Kewensis").) he was wrong in his surmise. The apparent sterility seems to be explicable by Hildebrand's discovery (608/5. "Bot. Zeitung," 1863 and 1865.) that in some orchids the ovules are not developed until pollinisation has occurred. (608/6. "Fertilisation of Orchids," Edition II., page 172. See Letter 633.)) Down, December 15th [1861]. I am so nearly ready for press that I will not ask for anything more; unless, indeed, you stumbled on Mormodes in flower. As I am writing I will just mention that I am convinced from the rudimentary state of the ovules, and from the state of the stigma, that the whole plant of Acropera luteola (and I believe A. Loddigesii) is male. Have you ever seen any form from the same countries which could be the females? Of course no answer is expected unless you have ever observed anything to bear on this. I may add [judging from the] state of the ovules and of the pollen [that]:-- Catasetum tridentatum is male (and never seeds, according to Schomburgk, whom you have accidentally misquoted in the "Vegetable Kingdom"). Monacanthus viridis is female. Myanthus barbatus is the hermaphrodite form of same species. LETTER 609. TO J.D. HOOKER. Down, December 18th [1861]. Thanks for your note. I have not written for a long time, for I always fancy, busy as you are, that my letters must be a bore; though I like writing, and always enjoy your notes. I can sympathise with you about fear of scarlet fever: to the day of my death I shall never forget all the sickening fear about the other children, after our poor little baby died of it. The "Genera Plantarum" must be a tremendous work, and no doubt very valuable (such a book, odd as it may appear, would be very useful even to me), but I cannot help being rather sorry at the length of time it must take, because I cannot enter on and understand your work. Will you not be puzzled when you come to the orchids? It seems to me orchids alone would be work for a man's lifetime; I cannot somehow feel satisfied with Lindley's classification; the Malaxeae and Epidendreae seem to me very artificially separated. (609/1. Pfitzer (in the "Pflanzenfamilien") places Epidendrum in the Laeliinae-Cattleyeae, Malaxis in the Liparidinae. He states that Bentham united the Malaxideae and Epidendreae.) Not that I have seen enough to form an opinion worth anything. Your African plant seems to be a vegetable Ornithorhynchus, and indeed much more than that. (609/2. See Sir J.D. Hooker, "On Welwitschia, a new genus of Gnetaceae." "Linn. Soc. Trans." XXIV., 1862-3.) The more I read about plants the more I get to feel that all phanerogams seem comparable with one class, as lepidoptera, rather than with one kingdom, as the whole insecta. (609/3. He wrote to Hooker (December 28th, 1861): "I wrote carelessly about the value of phanerogams; what I was thinking of was that the sub-groups seemed to blend so much more one into another than with most classes of animals. I suspect crustacea would show more difference in the extreme forms than phanerogams, but, as you say, it is wild speculation. Yet it is very strange what difficulty botanists seem to find in grouping the families together into masses.") Thanks for your comforting sentence about the accursed ducts (accursed though they be, I should like nothing better than to work at them in the allied orders, if I had time). I shall be ready for press in three or four weeks, and have got all my woodcuts drawn. I fear much that publishing separately will prove a foolish job, but I do not care much, and the work has greatly amused me. The Catasetum has not flowered yet! In writing to Lindley about an orchid which he sent me, I told him a little about Acropera, and in answer he suggests that Gongora may be its female. He seems dreadfully busy, and I feel that I have more right to kill you than to kill him; so can you send me one or at most two dried flowers of Gongora? if you know the habitat of Acropera luteola, a Gongora from the same country would be the best, but any true Gongora would do; if its pollen should prove as rudimentary as that of Monacanthus relatively to Catasetum, I think I could easily perceive it even in dried specimens when well soaked. I have picked a little out of Lecoq, but it is awful tedious hunting. Bates is getting on with his natural history travels in one volume. (609/4. H.W. Bates, the "Naturalist on the Amazons," 1863. See Volume I., Letters 123, 148, also "Life and Letters," Volume II., page 381.) I have read the first chapter in MS., and I think it will be an excellent book and very well written; he argues, in a good and new way to me, that tropical climate has very little direct relation to the gorgeous colouring of insects (though of course he admits the tropics have a far greater number of beautiful insects) by taking all the few genera common to Britain and Amazonia, and he finds that the species proper to the latter are not at all more beautiful. I wonder how this is in species of the same restricted genera of plants. If you can remember it, thank Bentham for getting my Primula paper printed so quickly. I do enjoy getting a subject off one's hands completely. I have now got dimorphism in structure in eight natural orders just like Primula. Asa Gray sent me dried flowers of a capital case in Amsinkia spectabilis, one of the Boragineae. I suppose you do not chance to have the plant alive at Kew. LETTER 610. TO A.G. MORE. Down, June 7th, 1862. If you are well and have leisure, will you kindly give me one bit of information: Does Ophrys arachnites occur in the Isle of Wight? or do the intermediate forms, which are said to connect abroad this species and the bee-orchis, ever there occur? Some facts have led me to suspect that it might just be possible, though improbable in the highest degree, that the bee [orchis] might be the self-fertilising form of O. arachnites, which requires insects' aid, something [in the same way] as we have self-fertilising flowers of the violet and others requiring insects. I know the case is widely different, as the bee is borne on a separate plant and is incomparably commoner. This would remove the great anomaly of the bee being a perpetual self-fertiliser. Certain Malpighiaceae for years produce only one of the two forms. What has set my head going on this is receiving to-day a bee having one alone of the best marked characters of O. arachnites. (610/1. Ophrys arachnites is probably more nearly allied to O. aranifera than to O. apifera. For a case somewhat analogous to that suggested see the description of O. scolopax in "Fertilisation of Orchids," Edition II., page 52.) Pray forgive me troubling you. LETTER 611. TO G. BENTHAM. Down, June 22nd [1862?]. Here is a piece of presumption! I must think that you are mistaken in ranking Hab[enaria] chlorantha (611/1. In Hooker's "Students' Flora," 1884, page 395, H. chlorantha is given as a subspecies of H. bifolia. Sir J.D. Hooker adds that they are "according to Darwin, distinct, and require different species of moths to fertilise them. They vary in the position and distances of their anther-cells, but intermediates occur." See "Fertilisation of Orchids," Edition II., page 73.) as a variety of H. bifolia; the pollen-masses and stigma differ more than in most of the best species of Orchis. When I first examined them I remember telling Hooker that moths would, I felt sure, fertilise them in a different manner; and I have just had proof of this in a moth sent me with the pollinia (which can be easily recognised) of H. chlorantha attached to its proboscis, instead of to the sides of its face, as an H. bifolia. Forgive me scribbling this way; but when a man gets on his hobby-horse he always is run away with. Anyhow, nothing here requires any answer. LETTER 612. TO J.D. HOOKER. Down, [September] 14th [1862]. Your letter is a mine of wealth, but first I must scold you: I cannot abide to hear you abuse yourself, even in joke, and call yourself a stupid dog. You, in fact, thus abuse me, because for long years I have looked up to you as the man whose opinion I have valued more on any scientific subject than any one else in the world. I continually marvel at what you know, and at what you do. I have been looking at the "Genera" (612/1. "Genera Plantarum," by Bentham and Hooker, Volume I., Part I., 1862.), and of course cannot judge at all of its real value, but I can judge of the amount of condensed facts under each family and genus. I am glad you know my feeling of not being able to judge about one's own work; but I suspect that you have been overworking. I should think you could not give too much time to Wellwitchia (I spell it different every time I write it) (612/2. "On Welwitschia," "Linn. Soc. Trans." [1862], XXIV., 1863.); at least I am sure in the animal kingdom monographs cannot be too long on the osculant groups. Hereafter I shall be excessively glad to read a paper about Aldrovanda (612/3. See "Insectivorous Plants," page 321.), and am very much obliged for reference. It is pretty to see how the caught flies support Drosera; nothing else can live. Thanks about plants with two kinds of anthers. I presume (if an included flower was a Cassia) (612/4. Todd has described a species of Cassia with an arrangement of stamens like the Melastomads. See Chapter 2.X.II.) that Cassia is like lupines, but with some stamens still more rudimentary. If I hear I will return the three Melastomads; I do not want them, and, indeed, have cuttings. I am very low about them, and have wasted enormous labour over them, and cannot yet get a glimpse of the meaning of the parts. I wish I knew any botanical collector to whom I could apply for seeds in their native land of any Heterocentron or Monochoetum; I have raised plenty of seedlings from your plants, but I find in other cases that from a homomorphic union one generally gets solely the parent form. Do you chance to know of any botanical collector in Mexico or Peru? I must not now indulge myself with looking after vessels and homologies. Some future time I will indulge myself. By the way, some time I want to talk over the alternation of organs in flowers with you, for I think I must have quite misunderstood you that it was not explicable. I found out the Verbascum case by pure accident, having transplanted one for experiment, and finding it to my astonishment utterly sterile. I formerly thought with you about rarity of natural hybrids, but I am beginning to change: viz., oxlips (not quite proven), Verbascum, Cistus (not quite proven), Aegilops triticoides (beautifully shown by Godron), Weddell's and your orchids (612/5. For Verbascum see "Animals and Plants," Edition II., Volume I., page 356; for Cistus, Ibid., Edition II., Volume I., page 356, Volume II., page 122; for Aegilops, Ibid., Edition II., Volume I., page 330, note.), and I daresay many others recorded. Your letters are one of my greatest pleasures in life, but I earnestly beg you never to write unless you feel somewhat inclined, for I know how hard you work, as I work only in the morning it is different with me, and is only a pleasant relaxation. You will never know how much I owe to you for your constant kindness and encouragement. LETTER 613. TO JOHN LUBBOCK (Lord Avebury). Cliff Cottage, Bournemouth, Hants, September 2nd [1862]. Hearty thanks for your note. I am so glad that your tour answered so splendidly. My poor patients (613/1. Mrs. Darwin and one of her sons, both recovering from scarlet fever.) got here yesterday, and are doing well, and we have a second house for the well ones. I write now in great haste to beg you to look (though I know how busy you are, but I cannot think of any other naturalist who would be careful) at any field of common red clover (if such a field is near you) and watch the hive-bees: probably (if not too late) you will see some sucking at the mouth of the little flowers and some few sucking at the base of the flowers, at holes bitten through the corollas. All that you will see is that the bees put their heads deep into the [flower] head and rout about. Now, if you see this, do for Heaven's sake catch me some of each and put in spirits and keep them separate. I am almost certain that they belong to two castes, with long and short proboscids. This is so curious a point that it seems worth making out. I cannot hear of a clover field near here. LETTER 614. TO JOHN LUBBOCK (Lord Avebury). Cliff Cottage, Bournemouth, Wednesday, September 3rd [1862]. I beg a million pardons. Abuse me to any degree, but forgive me: it is all an illusion (but almost excusable) about the bees. (614/1. H. Muller, "Fertilisation of Flowers," page 186, describes hive-bees visiting Trifolium pratense for the sake of the pollen. Darwin may perhaps have supposed that these were the variety of bees whose proboscis was long enough to reach the nectar. In "Cross and Self Fertilisation," page 361, Darwin describes hive-bees apparently searching for a secretion on the calyx. In the same passage in "Cross and Self Fertilisation" he quotes Muller as stating that hive-bees obtain nectar from red clover by breaking apart the petals. This seems to us a misinterpretation of the "Befruchtung der Blumen," page 224.) I do so hope that you have not wasted any time from my stupid blunder. I hate myself, I hate clover, and I hate bees. (FIGURE 10.--DIAGRAM OF CRUCIFEROUS FLOWER. FIGURE 11.--DISSECTION OF CRUCIFEROUS FLOWER. Laid flat open, showing by dotted lines the course of spiral vessels in all the organs; sepals and petals shown on one side alone, with the stamens on one side above with course of vessels indicated, but not prolonged. Near side of pistil with one spiral vessel cut away.) LETTER 615. TO J.D. HOOKER. Cliff Cottage, Bournemouth, September 11th, 1862. You once told me that Cruciferous flowers were anomalous in alternation of parts, and had given rise to some theory of dedoublement. Having nothing on earth to do here, I have dissected all the spiral vessels in a flower, and instead of burning my diagrams [Figures 10 and 11], I send them to you, you miserable man. But mind, I do not want you to send me a discussion, but just some time to say whether my notions are rubbish, and then burn the diagrams. It seems to me that all parts alternate beautifully by fours, on the hypothesis that two short stamens of outer whorl are aborted (615/1. The view given by Darwin is (according to Eichler) that previously held by Knuth, Wydler, Chatin, and others. Eichler himself believes that the flower is dimerous, the four longer stamens being produced by the doubling or splitting of the upper (i.e. antero-posterior) pair of stamens. If this view is correct, and there are good reasons for it, it throws much suspicion on the evidence afforded by the course of vessels, for there is no trace of the common origin of the longer stamens in the diagram (Figure 11). Again, if Eichler is right, the four vessels shown in the section of the ovary are misleading. Darwin afterwards gave a doubtful explanation of this, and concluded that the ovary is dimerous. See Letter 616.); and this view is perhaps supported by their being so few, only two sub-bundles in the two lateral main bundles, where I imagine two short stamens have aborted, but I suppose there is some valid objection against this notion. The course of the side vessels in the sepals is curious, just like my difficulty in Habenaria. (615/2. See Letter 605.) I am surprised at the four vessels in the ovarium. Can this indicate four confluent pistils? anyhow, they are in the right alternating position. The nectary within the base of the shorter stamens seems to cause the end sepals apparently, but not really, to arise beneath the lateral sepals. I think you will understand my diagrams in five minutes, so forgive me for bothering you. My writing this to you reminds me of a letter which I received yesterday from Claparede, who helped the French translatress of the "Origin" (615/3. The late Mlle. Royer.), and he tells me he had difficulty in preventing her (who never looked at a bee's cell) from altering my whole description, because she affirmed that an hexagonal prism must have an hexagonal base! Almost everywhere in the "Origin," when I express great doubt, she appends a note explaining the difficulty, or saying that there is none whatever!! (615/4. See "Life and Letters," II., page 387.) It is really curious to know what conceited people there are in the world (people, for instance, after looking at one Cruciferous flower, explain their homologies). This is a nice, but most barren country, and I can find nothing to look at. Even the brooks and ponds produce nothing. The country is like Patagonia. my wife is almost well, thank God, and Leonard is wonderfully improved ...Good God, what an illness scarlet fever is! The doctor feared rheumatic fever for my wife, but she does not know her risk. It is now all over. (FIGURE 12.) LETTER 616. TO J.D. HOOKER. Cliff Cottage, Bournemouth, Thursday Evening [September 18th, 1862]. Thanks for your pleasant note, which told me much news, and upon the whole good, of yourselves. You will be awfully busy for a time, but I write now to say that if you think it really worth while to send me a few Dielytra, or other Fumariaceous plant (which I have already tried in vain to find here) in a little tin box, I will try and trace the vessels; but please observe, I do not know that I shall have time, for I have just become wonderfully interested in experimenting on Drosera with poisons, etc. If you send any Fumariaceous plant, send if you can, also two or three single balsams. After writing to you, I looked at vessels of ovary of a sweet-pea, and from this and other cases I believe that in the ovary the midrib vessel alone gives homologies, and that the vessels on the edge of the carpel leaf often run into the wrong bundle, just like those on the sides of the sepals. Hence I [suppose] in Crucifers that the ovarium consists of two pistils; AA [Figure 12] being the midrib vessels, and BB being those formed of the vessels on edges of the two carpels, run together, and going to wrong bundles. I came to this conclusion before receiving your letter. I wonder why Asa Gray will not believe in the quaternary arrangement; I had fancied that you saw some great difficulty in the case, and that made me think that my notion must be wrong. LETTER 617. TO J.D. HOOKER. Down, September 27th [1862]. Masdevallia turns out nothing wonderful (617/1. This may refer to the homologies of the parts. He was unable to understand the mechanism of the flower.--"Fertilisation of Orchids," Edition II., page 136.); I was merely stupid about it; I am not the less obliged for its loan, for if I had lived till 100 years old I should have been uneasy about it. It shall be returned the first day I send to Bromley. I have steamed the other plants, and made the sensitive plant very sensitive, and shall soon try some experiments on it. But after all it will only be amusement. Nevertheless, if not causing too much trouble, I should be very glad of a few young plants of this and Hedysarum in summer (617/2. Hedysarum or Desmodium gyrans, the telegraph-plant.), for this kind of work takes no time and amuses me much. Have you seeds of Oxalis sensitiva, which I see mentioned in books? By the way, what a fault it is in Henslow's "Botany" that he gives hardly any references; he alludes to great series of experiments on absorption of poison by roots, but where to find them I cannot guess. Possibly the all-knowing Oliver may know. I can plainly see that the glands of Drosera, from rapid power (almost instantaneous) of absorption and power of movement, give enormous advantage for such experiments. And some day I will enjoy myself with a good set to work; but it will be a great advantage if I can get some preliminary notion on other sensitive plants and on roots. Oliver said he would speak about some seeds of Lythrum hyssopifolium being preserved for me. By the way, I am rather disgusted to find I cannot publish this year on Lythrum salicaria; I must make 126 additional crosses. All that I expected is true, but I have plain indication of much higher complexity. There are three pistils of different structure and functional power, and I strongly suspect altogether five kinds of pollen all different in this one species! (617/3. See "Forms of Flowers," Edition II., page 138.) By any chance have you at Kew any odd varieties of the common potato? I want to grow a few plants of every variety, to compare flowers, leaves, fruit, etc., as I have done with peas, etc. (617/4. "Animals and Plants," Edition II., Volume I., page 346. Compare also the similar facts with regard to cabbages, loc. cit., page 342. Some of the original specimens are in the Botanical Museum at Cambridge.) LETTER 618. J.D. HOOKER TO CHARLES DARWIN. (618/1. The following is part of Letter 144, Volume I. It refers to reviews of "Fertilisation of Orchids" in the "Gardeners' Chronicle," 1862, pages 789, 863, 910, and in the "Natural History Review," October, 1862, page 371.) November 7th, 1862. Dear old Darwin, I assure you it was not my fault! I worried Lindley over and over again to notice your orchid book in the "Chronicle" by the very broadest hints man could give. (618/2. See "Life and Letters," III., page 273.) At last he said, "really I cannot, you must do it for me," and so I did--volontiers. Lindley felt that he ought to have done it himself, and my main effort was to write it "a la Lindley," and in this alone I have succeeded--that people all think it is exactly Lindley's style!!! which diverts me vastly. The fact is, between ourselves, I fear that poor L. is breaking up--he said that he could not fix his mind on your book. He works himself beyond his mental or physical powers. And now, my dear Darwin, I may as well make a clean breast of it, and tell you that I wrote the "Nat. Hist. Review" notice too--to me a very difficult task, and one I fancied I failed in, comparatively. Of this you are no judge, and can be none; you told me to tell Oliver it pleased you, and so I am content and happy. LETTER 619. TO W.E. DARWIN. Down, 4th [about 1862-3?] I have been looking at the fertilisation of wheat, and I think possibly you might find something curious. I observed in almost every one of the pollen-grains, which had become empty and adhered to (I suppose the viscid) branching hairs of the stigma, that the pollen-tube was always (?) emitted on opposite side of grain to that in contact with the branch of the stigma. This seems very odd. The branches of the stigma are very thin, formed apparently of three rows of cells of hardly greater diameter than pollen-tube. I am astonished that the tubes should be able to penetrate the walls. The specimens examined (not carefully by me) had pollen only during few hours on stigma; and the mere SUSPICION has crossed me that the pollen-tubes crawl down these branches to the base and then penetrate the stigmatic tissue. (619/1. See Strasburger's "Neue Untersuchungen uber den Befruchtungsvorgang bei den Phanerogamen," 1884. In Alopecurus pratensis he describes the pollen as adhering to the end of a projection from the stigma where it germinates; the tube crawls along or spirally round this projection until it reaches the angle where the stigmatic branch is given off; here it makes an entrance and travels in the middle lamella between two cells.) The paleae open for a short period for stigma to be dusted, and then close again, and such travelling down would take place under protection. High powers and good adjustment are necessary. Ears expel anthers when kept in water in room; but the paleae apparently do not open and expose stigma; but the stigma could easily be artificially impregnated. If I were you I would keep memoranda of points worth attending to. 2.X.II. MELASTOMACEAE, 1862-1881. (620/1. The following series of letters (620-630) refers to the Melastomaceae and certain other flowers of analogous form. In 1862 Darwin attempted to explain the existence of two very different sets of stamens in these plants as a case of dimorphism, somewhat analogous to the state of things in Primula. In this view he was probably wrong, but this does not diminish the interest of the crossing experiments described in the letters. The persistence of his interest in this part of the subject is shown in the following passage from his Preface to the English translation of H. Muller's "Befruchtung der Blumen"; the passage is dated February, 1882, but was not published until the following year. "There exist also some few plants the flowers of which include two sets of stamens, differing in the shape of the anthers and in the colour of the pollen; and at present no one knows whether this difference has any functional significance, and this is a point which ought to be determined." It is not obvious why he spoke of the problem as if no light had been thrown on it, since in 1881 Fritz Muller had privately (see Letter 629) offered an explanation which Darwin was strongly inclined to accept. (620/2. H. Muller published ("Nature," August 4th, 1881) a letter from his brother Fritz giving the theory in question for Heeria. Todd ("American Naturalist," April 1882), described a similar state of things in Solanum rostratum and in Cassia: and H.O. Forbes ("Nature," August 1882, page 386) has done the same for Melastoma. In Rhexia virginica Mr. W.H. Leggett ("Bulletin Torrey Bot. Club, New York," VIII., 1881, page 102) describes the curious structure of the anther, which consists of two inflated portions and a tubular part connecting the two. By pressing with a blunt instrument on one of the ends, the pollen is forced out in a jet through a fine pore in the other inflated end. Mr. Leggett has seen bees treading on the anthers, but could not get near enough to see the pollen expelled. In the same journal, Volume IX., page 11, Mr. Bailey describes how in Heterocentron roseum, "upon pressing the bellows-like anther with a blunt pencil, the pollen was ejected to a full inch in distance." On Lagerstroemia as comparable with the Melastomads see Letter 689.) Fritz Muller's theory with regard to the Melastomads and a number of analogous cases in other genera are discussed in H. Muller's article in "Kosmos" (620/3. "Kosmos," XIII., 1883, page 241.), where the literature is given. F. Muller's theory is that in Heeria the yellow anthers serve merely as a means of attracting pollen-collecting bees, while the longer stamens with purple or crimson anthers supply pollen for fertilising purposes. If Muller is right the pollen from the yellow anthers would not normally reach the stigma. The increased vigour observed in the seedlings from the yellow anthers would seem to resemble the good effect of a cross between different individuals of the same species as worked out in "Cross and Self Fertilisation," for it is difficult to believe that the pollen of the purple anthers has become, by adaptation, less effective than that of the yellow anthers. In the letters here given there is some contradiction between the statements as to the position of the two sets of stamens in relation to the sepals. According to Eichler ("Bluthendiagramme, II., page 482) the longer stamens may be either epipetalous or episepalous in this family. The work on the Melastomads is of such intrinsic importance that we have thought it right to give the correspondence in considerable detail; we have done so in spite of the fact that Darwin arrived at no definite conclusion, and in spite of an element of confusion and unsatisfactoriness in the series of letters. This applies also to Letter 629, written after Darwin had learned Fritz Muller's theory, which is obscured by some errors or slips of the pen.) LETTER 620. TO G. BENTHAM. Down, February 3rd [1862?] As you so kindly helped me before on dimorphism, will you forgive me begging for a little further information, if in your power to give it? The case is that of the Melastomads with eight stamens, on which I have been experimenting. I am perplexed by opposed statements: Lindley says the stamens which face the petals are sterile; Wallich says in Oxyspora paniculata that the stamens which face the sepals are destitute of pollen; I find plenty of apparently good pollen in both sets of stamens in Heterocentron [Heeria], Monochoetum, and Centradenia. Can you throw any light on this? But there is another point on which I am more anxious for information. Please look at the enclosed miserable diagram. I find that the pollen of the yellow petal-facing stamens produce more than twice as much seed as the pollen of the purple sepal-facing stamens. This is exactly opposed to Lindley's statement--viz., that the petal-facing stamens are sterile. But I cannot at present believe that the case has any relation to abortion; it is hardly possible to believe that the longer and very curious stamens, which face the sepals in this Heterocentron, are tending to be rudimentary, though their pollen applied to their own flowers produces so much less seed. It is conformable with what we see in Primula that the [purple] sepal-facing anthers, which in the plant seen by me stood quite close on each side of the stigma, should have been rendered less fitted to fertilise the stigma than the stamens on the opposite side of the flower. Hence the suspicion has crossed me that if many plants of the Heterocentron roseum were examined, half would be found with the pistil nearly upright, instead of being rectangularly bent down, as shown in the diagram (620/4. According to Willis, "Flowering Plants and Ferns," 1897, Volume II., page 252, the style in Monochoetum, "at first bent downwards, moves slowly up till horizontal."); or, if the position of pistil is fixed, that in half the plants the petal-facing stamens would bend down, and in the other half of the plants the sepal-facing stamens would bend down as in the diagram. I suspect the former case, as in Centradenia I find the pistil nearly straight. Can you tell me? (620/5. No reply by Mr. Bentham to this or the following queries has been found.) Can the name Heterocentron have any reference to such diversity? Would it be asking too great a favour to ask you to look at dried specimens of Heterocentron roseum (which would be best), or of Monochoetum, or any eight-stamened Melastomad, of which you have specimens from several localities (as this would ensure specimens having been taken from distinct plants), and observe whether the pistil bends differently or stamens differently in different plants? You will at once see that, if such were the fact, it would be a new form of dimorphism, and would open up a large field of inquiry with respect to the potency of the pollen in all plants which have two sets of stamens--viz., longer and shorter. Can you forgive me for troubling you at such unreasonable length? But it is such waste of time to experiment without some guiding light. I do not know whether you have attended particularly to Melastoma; if you have not, perhaps Hooker or Oliver may have done so. I should be very grateful for any information, as it will guide future experiments. P.S.--Do you happen to know, when there are only four stamens, whether it is the petal or sepal-facers which are preserved? and whether in the four-stamened forms the pistil is rectangularly bent or is straight? LETTER 621. TO ASA GRAY. Down, February 16th [1862?]. I have been trying a few experiments on Melastomads; and they seem to indicate that the pollen of the two curious sets of anthers (i.e. the petal-facers and the sepal-facers) have very different powers; and it does not seem that the difference is connected with any tendency to abortion in the one set. Now I think I can understand the structure of the flower and means of fertilisation, if there be two forms,--one with the pistil bent rectangularly out of the flower, and the other with it nearly straight. Our hot-house and green-house plants have probably all descended by cuttings from a single plant of each species; so I can make out nothing from them. I applied in vain to Bentham and Hooker; but Oliver picked out some sentences from Naudin, which seem to indicate differences in the position of the pistil. I see that Rhexia grows in Massachusetts; and I suppose has two different sets of stamens. Now, if in your power, would you observe the position of the pistil in different plants, in lately opened flowers of the same age? (I specify this because in Monochaetum I find great changes of position in the pistils and stamens, as flower gets old). Supposing that my prophecy should turn out right, please observe whether in both forms the passage into the flower is not [on] the upper side of the pistil, owing to the basal part of the pistil lying close to the ring of filaments on the under side of the flower. Also I should like to know the colour of the two sets of anthers. This would take you only a few minutes, and is the only way I see that I can find out whether these plants are dimorphic in this peculiar way--i.e., only in the position of the pistil (621/1. In Exacum and in Saintpaulia the flowers are dimorphic in this sense: the style projects to either the right or the left side of the corolla, from which it follows that a right-handed flower would fertilise a left-handed one, and vice versa. See Willis, "Flowering Plants and Ferns," 1897, Volume I., page 73.) and in its relation to the two kinds of pollen. I am anxious about this, because if it should prove so, it will show that all plants with longer and shorter or otherwise different anthers will have to be examined for dimorphism. LETTER 622. TO ASA GRAY. March 15th [1862]. ...I wrote some little time ago about Rhexia; since then I have been carefully watching and experimenting on another genus, Monochaetum; and I find that the pistil is first bent rectangularly (as in the sketch sent), and then in a few days becomes straight: the stamens also move. If there be not two forms of Rhexia, will you compare the position of the part in young and old flowers? I have a suspicion (perhaps it will be proved wrong when the seed-capsules are ripe) that one set of anthers are adapted to the pistil in early state, and the other set for it in its later state. If bees visit the Rhexia, for Heaven's sake watch exactly how the anther and stigma strike them, both in old and young flowers, and give me a sketch. Again I say, do not hate me. LETTER 623. TO J.D. HOOKER. Leith Hill Place, Dorking, Thursday, 15th [May 1862]. You stated at the Linnean Society that different sets of seedling Cinchona (623/1. Cinchona is apparently heterostyled: see "Forms of Flowers," Edition II., page 134.) grew at very different rate, and from my Primula case you attributed it probably to two sorts of pollen. I confess I thought you rash, but I now believe you were quite right. I find the yellow and crimson anthers of the same flower in the Melastomatous Heterocentron roseum have different powers; the yellow producing on the same plant thrice as many seeds as the crimson anthers. I got my neighbour's most skilful gardener to sow both kinds of seeds, and yesterday he came to me and said it is a most extraordinary thing that though both lots have been treated exactly alike, one lot all remain dwarfs and the other lot are all rising high up. The dwarfs were produced by the pollen of the crimson anthers. In Monochaetum ensiferum the facts are more complex and still more strange; as the age and position of the pistils comes into play, in relation to the two kinds of pollen. These facts seem to me so curious that I do not scruple to ask you to see whether you can lend me any Melastomad just before flowering, with a not very small flower, and which will endure for a short time a greenhouse or sitting-room; when fertilised and watered I could send it to Mr. Turnbull's to a cool stove to mature seed. I fully believe the case is worth investigation. P.S.--You will not have time at present to read my orchid book; I never before felt half so doubtful about anything which I published. When you read it, do not fear "punishing" me if I deserve it. Adios. I am come here to rest, which I much want. Whenever you have occasion to write, pray tell me whether you have Rhododendron Boothii from Bhootan, with a smallish yellow flower, and pistil bent the wrong way; if so, I would ask Oliver to look for nectary, for it is an abominable error of Nature that must be corrected. I could hardly believe my eyes when I saw the pistil. LETTER 624. TO ASA GRAY. January 19th [1863]. I have been at those confounded Melastomads again; throwing good money (i.e. time) after bad. Do you remember telling me you could see no nectar in your Rhexia? well, I can find none in Monochaetum, and Bates tells me that the flowers are in the most marked manner neglected by bees and lepidoptera in Amazonia. Now the curious projections or horns to the stamens of Monochaetum are full of fluid, and the suspicion occurs to me that diptera or small hymenoptera may puncture these horns like they puncture (proved since my orchid book was published) the dry nectaries of true Orchis. I forget whether Rhexia is common; but I very much wish you would next summer watch on a warm day a group of flowers, and see whether they are visited by small insects, and what they do. LETTER 625. TO I.A. HENRY. Down, January 20th [1863]. ...You must kindly permit me to mention any point on which I want information. If you are so inclined, I am curious to know from systematic experiments whether Mr. D. Beaton's statement that the pollen of two shortest anthers of scarlet Pelargonium produce dwarf plants (625/1. See "Animals and Plants," Edition II., Volume II., page 150, for a brief account of Darwin's experiments on this genus. Also loc. cit., page 338 (note), for a suggested experiment.), in comparison with plants produced from the same mother-plant by the pollen of longer stamens from the same flower. It would aid me much in some laborious experiments on Melastomads. I confess I feel a little doubtful; at least, I feel pretty nearly sure that I know the meaning of short stamens in most plants. This summer (for another object) I crossed Queen of Scarlet Pelargonium with pollen of long and short stamens of multiflora alba, and it so turns out that plants from short stamens are the tallest; but I believe this to have been mere chance. My few crosses in Pelargonium were made to get seed from the central peloric or regular flower (I have got one from peloric flower by pollen of peloric), and this leads me to suggest that it would be very interesting to test fertility of peloric flowers in three ways,--own peloric pollen on peloric stigma, common pollen on peloric stigma, peloric pollen on common stigma of same species. My object is to discover whether with change of structure of flower there is any change in fertility of pollen or of female organs. This might also be tested by trying peloric and common pollen on stigma of a distinct species, and conversely. I believe there is a peloric and common variety of Tropaeolum, and a peloric or upright and common variation of some species of Gloxinia, and the medial peloric flowers of Pelargonium, and probably others unknown to me. LETTER 626. TO I.A. HENRY. Hartfield, May 2nd [1863]. In scarlet dwarf Pelargonium, you will find occasionally an additional and abnormal stamen on opposite and lower side of flower. Now the pollen of this one occasional short stamen, I think, very likely would produce dwarf plants. If you experiment on Pelargonium I would suggest your looking out for this single stamen. I observed fluctuations in length of pistil in Phloxes, but thought it was mere variability. If you could raise a bed of seedling Phloxes of any species except P. Drummondii, it would be highly desirable to see if two forms are presented, and I should be very grateful for information and flowers for inspection. I cannot remember, but I know that I had some reason to look after Phloxes. (626/1. See "Forms of Flowers," Edition II., page 119, where the conjecture is hazarded that Phlox subulata shows traces of a former heterostyled condition.) I do not know whether you have used microscopes much yet. It adds immensely to interest of all such work as ours, and is indeed indispensable for much work. Experience, however, has fully convinced me that the use of the compound without the simple microscope is absolutely injurious to progress of N[atural] History (excepting, of course, with Infusoria). I have, as yet, found no exception to the rule, that when a man has told me he works with the compound alone his work is valueless. LETTER 627. TO ASA GRAY. March 20th [1863]. I wrote to him [Dr. H. Cruger, of Trinidad] to ask him to observe what the insects did in the flowers of Melastomaceae: he says not proper season yet, but that on one species a small bee seemed busy about the horn-like appendages to the anthers. It will be too good luck if my study of the flowers in the greenhouse has led me to right interpretation of these appendages. LETTER 628. TO J.D. HOOKER. Down, November 28th [1871]. If you had come here on Sunday I should have asked you whether you could give me seed or seedlings of any Melastomad which would flower soon to experiment on! I wrote also to J. Scott to ask if he could give me seed. Several years ago I raised a lot of seedlings of a Melastomad greenhouse bush (Monochaetus or some such name) (628/1. Monochaetum.) from stigmas fertilised separately by the two kinds of pollen, and the seedlings differed remarkably in size, and whilst young, in appearance; and I never knew what to think of the case (so you must not use it), and have always wished to try again, but they are troublesome beasts to fertilise. On the other hand I could detect no difference in the product from the two coloured anthers of Clarkia. (628/2. Clarkia has eight stamens divided into two groups which differ in the colour of the anthers.) If you want to know further particulars of my experiments on Monochaetum (?) and Clarkia, I will hunt for my notes. You ask about difference in pollen in the same species. All dimorphic and trimorphic plants present such difference in function and in size. Lythrum and the trimorphic Oxalis are the most wonderful cases. The pollen of the closed imperfect cleistogamic flowers differ in the transparency of the integument, and I think in size. The latter point I could ascertain from my notes. The pollen or female organs must differ in almost every individual in some manner; otherwise the pollen of varieties and even distinct individuals of same varieties would not be so prepotent over the individual plant's own pollen. Here follows a case of individual differences in function of pollen or ovules or both. Some few individuals of Reseda odorata and R. lutea cannot be fertilised, or only very rarely, by pollen of the same plant, but can by pollen of any other individual. I chanced to have two plants of R. odorata in this state; so I crossed them and raised five seedlings, all of which were self sterile and all perfectly fertile with pollen of any other individual mignonette. So I made a self sterile race! I do not know whether these are the kinds of facts which you require. Think whether you can help me to seed or better seedlings (not cuttings) of any Melastomad. LETTER 629. TO F. MULLER. Down, March 20th, 1881. I have received the seeds and your most interesting letter of February 7th. The seeds shall be sown, and I shall like to see the plants sleeping; but I doubt whether I shall make any more detailed observations on this subject, as, now that I feel very old, I require the stimulus of some novelty to make me work. This stimulus you have amply given me in your remarkable view of the meaning of the two-coloured stamens in many flowers. I was so much struck with this fact with Lythrum, that I began experimenting on some Melastomaceae, which have two sets of extremely differently coloured anthers. After reading your letter I turned to my notes (made 20 years ago!) to see whether they would support or contradict your suggestion. I cannot tell yet, but I have come across one very remarkable result, that seedlings from the crimson anthers were not 11/20ths of the size of seedlings from the yellow anthers of the same flowers. Fewer good seeds were produced by the crimson pollen. I concluded that the shorter stamens were aborting, and that the pollen was not good. (629/1. "Shorter stamens" seems to be a slip of the pen for "longer,"--unless the observations were made on some genus in which the structure is unusual.) The mature pollen is incoherent, and must be [word illegible] against the visiting insect's body. I remembered this, and I find it said in my EARLY notes that bees would never visit the flowers for pollen. This made me afterwards write to the late Dr. Cruger in the West Indies, and he observed for me the flowers, and saw bees pressing the anthers with their mandibles from the base upwards, and this forced a worm-like thread of pollen from the terminal pore, and this pollen the bees collected with their hind legs. So that the Melastomads are not opposed to your views. I am now working on the habits of worms, and it tires me much to change my subject; so I will lay on one side your letter and my notes, until I have a week's leisure, and will then see whether my facts bear on your views. I will then send a letter to "Nature" or to the Linn. Soc., with the extract of your letter (and this ought to appear in any case), with my own observations, if they appear worth publishing. The subject had gone out of my mind, but I now remember thinking that the imperfect action of the crimson stamens might throw light on hybridism. If this pollen is developed, according to your view, for the sake of attracting insects, it might act imperfectly, as well as if the stamens were becoming rudimentary. (629/2. As far as it is possible to understand the earlier letters it seems that the pollen of the shorter stamens, which are adapted for attracting insects, is the most effective.) I do not know whether I have made myself intelligible. LETTER 630. TO W. THISELTON-DYER. Down, March 21st [1881]. I have had a letter from Fritz Muller suggesting a novel and very curious explanation of certain plants producing two sets of anthers of different colour. This has set me on fire to renew the laborious experiments which I made on this subject, now 20 years ago. Now, will you be so kind as to turn in your much worked and much holding head, whether you can think of any plants, especially annuals, producing 2 such sets of anthers. I believe that this is the case with Clarkia elegans, and I have just written to Thompson for seeds. The Lythraceae must be excluded, as these are heterostyled. I have got seeds from Dr. King of some Melastomaceae, and will write to Veitch to see if I can get the Melastomaceous genera Monochaetum and Heterocentron or some such name, on which I before experimented. Now, if you can aid me, I know that you will; but if you cannot, do not write and trouble yourself. 2.X.III. CORRESPONDENCE WITH JOHN SCOTT, 1862-1871. "If he had leisure he would make a wonderful observer, to my judgment; I have come across no one like him."--Letter to J.D. Hooker, May 29th [1863]. (631/1. The following group of letters to John Scott, of whom some account is given elsewhere (Volume I., Letters 150 and 151, and Index.) deal chiefly with experimental work in the fertilisation of flowers. In addition to their scientific importance, several of the letters are of special interest as illustrating the encouragement and friendly assistance which Darwin gave to his correspondent.) LETTER 631. JOHN SCOTT TO CHARLES DARWIN. Edinburgh Botanic Gardens, November 11th, 1862. I take the liberty of addressing you for the purpose of directing your attention to an error in one of your ingenious explanations of the structural adaptations of the Orchidaceae in your late work. This occurs in the genus Acropera, two species of which you assume to be unisexual, and so far as known represented by male individuals only. Theoretically you have no doubt assigned good grounds for this view; nevertheless, experimental observations that I am now making have already convinced me of its fallacy. And I thus hurriedly, and as you may think prematurely, direct your attention to it, before I have seen the final result of my own experiment, that you might have the longer time for reconsidering the structure of this genus for another edition of your interesting book, if indeed it be not already called for. I am furthermore induced to communicate the results of my yet imperfect experiments in the belief that the actuating principle of your late work is the elicitation of truth, and that you will gladly avail yourself of this even at the sacrifice of much ingenious theoretical argumentation. Since I have had an opportunity of perusing your work on orchid fertilisation, my attention has been particularly directed to the curiously constructed floral organs of Acropera. I unfortunately have as yet had only a few flowers for experimental enquiry, otherwise my remarks might have been clearer and more satisfactory. Such as they are, however, I respectfully lay [them] before you, with a full assurance of their veracity, and I sincerely trust that as such you will receive them. Your observations seem to have been chiefly directed to the A. luteola, mine to the A. Loddigesii, which, however, as you remark, is in a very similar constructural condition with the former; having the same narrow stigmatic chamber, abnormally developed placenta, etc. In regard to the former point--contraction of stigmatic chamber--I may remark that it does not appear to be absolutely necessary that the pollen-masses penetrate this chamber for effecting fecundation. Thus a raceme was produced upon a plant of A. Loddigesii in the Botanic Gardens here lately; upon this I left only six flowers. These I attempted to fertilise, but with two only of the six have I been successful: I succeeded in forcing a single pollen-mass into the stigmatic chamber of one of the latter, but I failed to do this on the other; however, by inserting a portion of a pedicel with a pollinium attached, I caused the latter to adhere, with a gentle press, to the mouth of the stigmatic chamber. Both of these, as I have already remarked, are nevertheless fertilised; one of them I have cut off for examination, and its condition I will presently describe; the other is still upon the plant, and promises fair to attain maturity. In regard to the other four flowers, I may remark that though similarly fertilised--part having pollinia inserted, others merely attached--they all withered and dropped off without the least swelling of the ovary. Can it be, then, that this is really an [andro-monoecious] species?--part of the flowers male, others truly hermaphrodite. In making longitudinal sections of the fertilised ovary before mentioned, I found the basal portion entirely destitute of ovules, their place being substituted by transparent cellular ramification of the placentae. As I traced the placentae upwards, the ovules appeared, becoming gradually more abundant towards its apex. A transverse section near the apex of the ovary, however, still exhibited a more than ordinary placental development--i.e. [congenitally?] considered--each end giving off two branches, which meet each other in the centre of the ovary, the ovules being irregularly and sparingly disposed upon their surfaces. In regard to the mere question of fertilisation, then, I am perfectly satisfied, but there are other points which require further elucidation. Among these I may particularly refer to the contracted stigmatic chamber, and the slight viscidity of its disk. The latter, however, may be a consequence of uncongenial conditions--as you do not mention particularly its examination by any author in its natural habitat. If such be the case, the contracted stigmatic chamber will offer no real difficulty, should the viscous exudations be only sufficient to render the mouth adhesive. For, as I have already shown, the pollen-tubes may be emitted in this condition, and effect fecundation without being in actual contact with the stigmatic surface, as occurs pretty regularly in the fertilisation of the Stapelias, for example. But, indeed, your own discovery of the independent germinative capabilities of the pollen-grains of certain Orchidaceae is sufficiently illustrative of this. I may also refer to the peculiar abnormal condition that many at least of the ovaries present in a comparative examination of the placentae, and of which I beg to suggest the following explanation, though it is as yet founded on limited observations. In examining certain young ovaries of A. Loddigesii, I found some of them filled with the transparent membranous fringes of more or less distinctly cellular matter, which, from your description of the ovaries of luteola, appears to differ simply in the greater development in the former species. Again, in others I found small mammillary bodies, which appeared to be true ovules, though I could not perfectly satisfy myself as to the existence of the micropyle or nucleus. I unfortunately neglected to apply any chemical test. The fact, however, that in certain of the examined ovaries few or none of the latter bodies occurred--the placenta alone being developed in an irregular membranous form, taken in conjunction with the results of my experiments--before alluded to--on their fertilisation, leads me to infer that two sexual conditions are presented by the flowers of this plant. In short, that many of the ovaries are now normally abortive, though Nature occasionally makes futile efforts for their perfect development, in the production of ovuloid bodies; these then I regard as the male flowers. The others that are still capable of fertilisation, and likewise possessing male organs, are hermaphrodite, and must, I think, from the results of your comparative examinations, present a somewhat different condition; as it can scarcely be supposed that ovules in the condition you describe could ever be fertilised. This is at least the most plausible explanation I can offer for the different results in my experiments on the fertilisation of apparently similar morphologically constructed flowers; others may, however, occur to you. Here there is not, as in the Catasetum, any external change visible in the respective unisexual and bisexual flowers. And yet it would appear from your researches that the ovules of Acropera are in a more highly atrophied condition than occurs in Catasetum, though, as you likewise remark, M. Neumann has never succeeded in fertilising C. tridentatum. If there be not, then, an arrangement of the reproductive structures, such as I have indicated, how can the different results in M. Neumann's experiments and mine be accounted for? However, as you have examined many flowers of both A. luteola and Loddigesii, such a difference in the ovulary or placental structures could scarcely have escaped your observation. But, be this as it may, the--to me at least--demonstrated fact still remains, that certain flowers of A. Loddigesii are capable of fertilisation, and that, though there are good grounds for supposing that important physiological changes are going on in the sexual phenomena of this species, there is no evidence whatever for supposing that external morphological changes have so masked certain individuals as to prevent their recognition. I would now, sir, in conclusion beg you to excuse me for this infringement upon your valuable time, as I have been induced to write you in the belief that you have had negative results from other experimenters, before you ventured to propose your theoretical explanation, and consequently that you have been unknowingly led into error. I will continue, as opportunities present themselves, to examine the many peculiarities you have pointed out in this as well as others of the Orchid family; and at present I am looking forward with anxiety for the maturation of the ovary of A. Loddigesii, which will bear testimony to the veracity of the remarks I have ventured to lay before you. LETTER 632. TO J.D. HOOKER. Down, 18th [November 1862]. Strange to say, I have only one little bother for you to-day, and that is to let me know about what month flowers appear in Acropera Loddigesii and luteola; for I want extremely to beg a few more flowers, and if I knew the time I would keep a memorandum to remind you. Why I want these flowers is (and I am much alarmed) that Mr. J. Scott, of Bot. Garden of Edinburgh (do you know anything of him?) has written me a very long and clever letter, in which he confirms most of my observations; but tells me that with much difficulty he managed to get pollen into orifice, or as far as mouth of orifice, of six flowers of A. Loddigesii (the ovarium of which I did not examine), and two pods set; one he gathered, and saw a very few ovules, as he thinks, on the large and mostly rudimentary placenta. I shall be most curious to hear whether the other pod produces a good lot of seed. He says he regrets that he did not test the ovules with chemical agents: does he mean tincture of iodine? He suggests that in a state of nature the viscid matter may come to the very surface of stigmatic chamber, and so pollen-masses need not be inserted. This is possible, but I should think improbable. Altogether the case is very odd, and I am very uneasy, for I cannot hope that A. Loddigesii is hermaphrodite and A. luteola the male of the same species. Whenever I can get Acropera would be a very good time for me to look at Vanda in spirits, which you so kindly preserved for me. LETTER 633. TO J. SCOTT. (633/1. The following is Darwin's reply to the above letter from Scott. In the first edition of "Fertilisation of Orchids" (page 209) he assumed that the sexes in Acropera, as in Catasetum, were separate. In the second edition (page 172) he writes: "I was, however, soon convinced of my error by Mr. Scott, who succeeded in artificially fertilising the flowers with their own pollen. A remarkable discovery by Hildebrand (633/2. "Bot. Zeitung," 1863 and 1865.), namely, that in many orchids the ovules are not developed unless the stigma is penetrated by the pollen-tubes...explains the state of the ovarium in Acropera, as observed by me." In regard to this subject see Letter 608.) Down, November 12th, 1862. I thank you most sincerely for your kindness in writing to me, and for [your] very interesting letter. Your fact has surprised me greatly, and has alarmed me not a little, for if I am in error about Acropera I may be in error about Catasetum. Yet when I call to mind the state of the placentae in A. luteola, I am astonished that they should produce ovules. You will see in my book that I state that I did not look at the ovarium of A. Loddigesii. Would you have the kindness to send me word which end of the ovarium is meant by apex (that nearest the flower?), for I must try and get this species from Kew and look at its ovarium. I shall be extremely curious to hear whether the fruit, which is now maturing, produces a large number of good and plump seed; perhaps you may have seen the ripe capsules of other Vandeae, and may be able to form some conjecture what it ought to produce. In the young, unfertilised ovaria of many Vandeae there seemed an infinitude of ovules. In desperation it occurs to me as just possible, as almost everything in nature goes by gradation, that a properly male flower might occasionally produce a few seeds, in the same manner as female plants sometimes produce a little pollen. All your remarks seem to me excellent and very interesting, and I again thank you for your kindness in writing to me. I am pleased to observe that my description of the structure of Acropera seems to agree pretty well with what you have observed. Does it not strike you as very difficult to understand how insects remove the pollinia and carry them to the stigmas? Your suggestion that the mouth of the stigmatic cavity may become charged with viscid matter and thus secure the pollinia, and that the pollen-tubes may then protrude, seems very ingenious and new to me; but it would be very anomalous in orchids, i.e. as far as I have seen. No doubt, however, though I tried my best, I shall be proved wrong in many points. Botany is a new subject to me. With respect to the protrusion of pollen-tubes, you might like to hear (if you do not already know the fact) that, as I saw this summer, in the little imperfect flowers of Viola and Oxalis, which never open, the pollen-tubes always come out of the pollen-grain, whilst still in the anthers, and direct themselves in a beautiful manner to the stigma seated at some little distance. I hope that you will continue your very interesting observations. LETTER 634. TO J. SCOTT. Down, November 19th [1862]. I am much obliged for your letter, which is full of interesting matter. I shall be very glad to look at the capsule of the Acropera when ripe, and pray present my thanks to Mr. MacNab. (634/1. See Letter 608 (Lindley, December 15th, 1861). Also "Fertilisation of Orchids," Edition II., page 172, for an account of the observations on Acropera which were corrected by Scott.) I should like to keep it till I could get a capsule of some other member of the Vandeae for comparison, but ultimately all the seeds shall be returned, in case you would like to write any notice on the subject. It was, as I said (634/2. Letter 633.), only "in desperation" that I suggested that the flower might be a male and occasionally capable of producing a few seeds. I had forgotten Gartner's remark; in fact, I know only odds and ends of Botany, and you know far more. One point makes the above view more probable in Acropera than in other cases, viz. the presence of rudimentary placentae or testae, for I cannot hear that these have been observed in the male plants. They do not occur in male Lychnis dioica, but next spring I will look to male holly flowers. I fully admit the difficulty of similarity of stigmatic chamber in the two Acroperas. As far as I remember, the blunt end of pollen-mass would not easily even stick in the orifice of the chamber. Your view may be correct about abundance of viscid matter, but seems rather improbable. Your facts about female flowers occurring where males alone ought to occur is new to me; if I do not hear that you object, I will quote the Zea case on your authority in what I am now writing on the varieties of the maize. (634/3. See "Animals and Plants," Edition II., Volume I., page 339: "Mr. Scott has lately observed the rarer case of female flowers on a true male panicle, and likewise hermaphrodite flowers." Scott's paper on the subject is in "Trans. Bot. Soc. Edinburgh," Volume VIII. See Letter 151, Volume I.) I am glad to hear that you are now working on the most curious subject of parthenogenesis. I formerly fancied that I observed female Lychnis dioica seeded without pollen. I send by this post a paper on Primula, which may interest you. (634/4. "Linn. Soc. Journal," 1862.) I am working on the subject, and if you should ever observe any analogous case I should be glad to hear. I have added another very clever pamphlet by Prof. Asa Gray. Have you a copy of my Orchis book? If you have not, and would like one, I should be pleased to send one. I plainly see that you have the true spirit of an experimentalist and good observer. Therefore, I ask whether you have ever made any trials on relative fertility of varieties of plants (like those I quote from Gartner on the varieties of Verbascum). I much want information on this head, and on those marvellous cases (as some Lobelias and Crinum passiflora) in which a plant can be more easily fertilised by the pollen of another species than by its own good pollen. I am compelled to write in haste. With many thanks for your kindness. LETTER 635. TO J. SCOTT. Down, 20th [1862?]. What a magnificent capsule, and good Heavens, what a number of seeds! I never before opened pods of larger orchids. It did not signify a few seed being lost, as it would be hopeless to estimate number in comparison with other species. If you sow any, had you not better sow a good many? so I enclose small packet. I have looked at the seeds; I never saw in the British orchids nearly so many empty testae; but this goes for nothing, as unnatural conditions would account for it. I suspect, however, from the variable size and transparency, that a good many of the seeds when dry (and I have put the capsule on my chimney-piece) will shrivel up. So I will wait a month or two till I get the capsule of some large Vandeae for comparison. It is more likely that I have made some dreadful blunder about Acropera than that it should be male yet not a perfect male. May there be some sexual relation between A. Loddigesii and luteola; they seem very close? I should very much like to examine the capsule of the unimpregnated flower of A. Loddigesii. I have got both species from Kew, but whether we shall have skill to flower them I know not. One conjectures that it is imperfect male; I still should incline to think it would produce by seed both sexes. But you are right about Primula (and a very acute thought it was): the long-styled P. sinensis, homomorphically fertilised with own-form pollen, has produced during two successive homomorphic generations only long-styled plants. (635/1. In "Forms of Flowers," Edition II., page 216, a summary of the transmission of forms in the "homomorphic" unions of P. sinensis is given. Darwin afterwards used "illegitimate" for homomorphic, and "legitimate" for "heteromorphic" ("Forms of Flowers," Edition i., page 24).) The short-styled the same, i.e. produced short-styled for two generations with the exception of a single plant. I cannot say about cowslips yet. I should like to hear your case of the Primula: is it certainly propagated by seed? LETTER 636. TO J. SCOTT. Down, December 3rd, [1862?]. What a capital observer you are! and how well you have worked the primulas. All your facts are new to me. It is likely that I overrate the interest of the subject; but it seems to me that you ought to publish a paper on the subject. It would, however, greatly add to the value if you were to cover up any of the forms having pistil and anther of the same height, and prove that they were fully self-fertile. The occurrence of dimorphic and non-dimorphic species in the same genus is quite the same as I find in Linum. (636/1. Darwin finished his paper on Linum in December 1862, and it was published in the "Linn. Soc. Journal" in 1863.) Have any of the forms of Primula, which are non-dimorphic, been propagated for some little time by seed in garden? I suppose not. I ask because I find in P. sinensis a third rather fluctuating form, apparently due to culture, with stigma and anthers of same height. I have been working successive generations homomorphically of this Primula, and think I am getting curious results; I shall probably publish next autumn; and if you do not (but I hope you will) publish yourself previously, I should be glad to quote in abstract some of your facts. But I repeat that I hope you will yourself publish. Hottonia is dimorphic, with pollen of very different sizes in the two forms. I think you are mistaken about Siphocampylus, but I feel rather doubtful in saying this to so good an observer. In Lobelia the closed pistil grows rapidly, and pushes out the pollen and then the stigma expands, and the flower in function is monoecious; from appearance I believe this is the case with your plant. I hope it is so, for this plant can hardly require a cross, being in function monoecious; so that dimorphism in such a case would be a heavy blow to understanding its nature or good in all other cases. I see few periodicals: when have you published on Clivia? I suppose that you did not actually count the seeds in the hybrids in comparison with those of the parent-forms; but this is almost necessary after Gartner's observations. I very much hope you will make a good series of comparative trials on the same plant of Tacsonia. (636/2. See Scott in "Linn. Soc. Journal," VIII.) I have raised 700-800 seedlings from cowslips, artificially fertilised with care; and they presented not a hair's-breadth approach to oxlips. I have now seed in pots of cowslip fertilised by pollen of primrose, and I hope they will grow; I have also got fine seedlings from seed of wild oxlips; so I hope to make out the case. You speak of difficulties on Natural Selection: there are indeed plenty; if ever you have spare time (which is not likely, as I am sure you must be a hard worker) I should be very glad to hear difficulties from one who has observed so much as you have. The majority of criticisms on the "Origin" are, in my opinion, not worth the paper they are printed on. Sir C. Lyell is coming out with what, I expect, will prove really good remarks. (636/3. Lyell's "Antiquity of Man" was published in the spring of 1863. In the "Life and Letters," Volume III., pages 8, 11, Darwin's correspondence shows his deep disappointment at what he thought Lyell's half-heartedness in regard to evolution. See Letter 164, Volume I.) Pray do not think me intrusive; but if you would like to have any book I have published, such as my "Journal of Researches" or the "Origin," I should esteem it a compliment to be allowed to send it. Will you permit me to suggest one experiment, which I should much like to see tried, and which I now wish the more from an extraordinary observation by Asa Gray on Gymnadenia tridentata (in number just out of Silliman's N. American Journal) (636/4. In Gymnadenia tridentata, according to Asa Gray, the anther opens in the bud, and the pollen being somewhat coherent falls on the stigma and on the rostellum which latter is penetrated by the pollen-tubes. "Fertilisation of Orchids," Edition II., page 68. Asa Gray's papers are in "American Journal of Science," Volume XXXIV., 1862, and XXXVI., 1863.); namely, to split the labellum of a Cattleya, or of some allied orchis, remove caudicle from pollen-mass (so that no loose grains are about) and put it carefully into the large tongue-like rostellum, and see if pollen-tubes will penetrate, or better, see if capsule will swell. Similar pollen-masses ought to be put on true stigmas of two or three other flowers of same plants for comparison. It is to discover whether rostellum yet retains some of its primordial function of being penetrated by pollen-tubes. You will be sorry that you ever entered into correspondence with me. But do not answer till at leisure, and as briefly as you like. My handwriting, I know, is dreadfully bad. Excuse this scribbling paper, as I can write faster on it, and I have a rather large correspondence to keep up. LETTER 637. TO J. SCOTT. Down, January 21st, 1863. I thank you for your very interesting letter; I must answer as briefly as I can, for I have a heap of other letters to answer. I strongly advise you to follow up and publish your observations on the pollen-tubes of orchids; they promise to be very interesting. If you could prove what I only conjectured (from state of utriculi in rostellum and in stigma of Catasetum and Acropera) that the utriculi somehow induce, or are correlated with, penetration of pollen-tubes you will make an important physiological discovery. I will mention, as worth your attention (and what I have anxiously wished to observe, if time had permitted, and still hope to do)--viz., the state of tissues or cells of stigma in an utterly sterile hybrid, in comparison with the same in fertile parent species; to test these cells, immerse stigmas for 48 hours in spirits of wine. I should expect in hybrids that the cells would not show coagulated contents. It would be an interesting discovery to show difference in female organs of hybrids and pure species. Anyhow, it is worth trial, and I recommend you to make it, and publish if you do. The pollen-tubes directing themselves to stigma is also very curious, though not quite so new, but well worth investigation when you get Cattleya, etc., in flower. I say not so new, for remember small flowers of Viola and Oxalis; or better, see Bibliography in "Natural History Review," No. VIII., page 419 (October, 1862) for quotation from M. Baillon on pollen-tubes finding way from anthers to stigma in Helianthemum. I should doubt gum getting solid from [i.e. because of] continued secretion. Why not sprinkle fresh plaster of Paris and make impenetrable crust? (637/1. The suggestion that the stigma should be covered with a crust of plaster of Paris, pierced by a hole to allow the pollen-tubes to enter, bears a resemblance to Miyoshi's experiments with germinating pollen and fungal spores. See "Pringsheim's Jahrbucher," 1895; "Flora," 1894.) You might modify experiment by making little hole in one lower corner, and see if tubes find it out. See in my future paper on Linum pollen and stigma recognising each other. If you will tell me that pollen smells the stigma I will try and believe you; but I will not believe the Frenchman (I forget who) who says that stigma of Vanilla actually attracts mechanically, by some unknown force, the solid pollen-masses to it! Read Asa Gray in 2nd Review of my Orchis book on pollen of Gymnadenia penetrating rostellum. I can, if you like, lend you these Reviews; but they must be returned. R. Brown, I remember, says pollen-tubes separate from grains before the lower ends of tubes reach ovules. I saw, and was interested by, abstract of your Drosera paper (637/2. A short note on the irritability of Drosera in the "Trans. Bot. Soc. Edin." Volume VII.); we have been at very much the same work. LETTER 638. TO J. SCOTT. Down, February 16th [1863]. Absence from home has prevented me from answering you sooner. I should think that the capsule of Acropera had better be left till it shows some signs of opening, as our object is to judge whether the seeds are good; but I should prefer trusting to your better judgment. I am interested about the Gongora, which I hope hereafter to try myself, as I have just built a small hot-house. Asa Gray's observations on the rostellum of Gymnadenia are very imperfect, yet worth looking at. Your case of Imatophyllum is most interesting (638/1. A sucker of Imatophyllum minatum threw up a shoot in which the leaves were "two-ranked instead of four-ranked," and showed other differences from the normal.--"Animals and Plants," Edition II., Volume I., page 411.); even if the sport does not flower it will be worth my giving. I did not understand, or I had forgotten, that a single frond on a fern will vary; I now see that the case does come under bud-variation, and must be given by me. I had thought of it only as proof [of] inheritance in cryptogams; I am much obliged for your correction, and will consult again your paper and Mr. Bridgeman's. (638/2. The facts are given in "Animals and Plants," Edition II., Volume I., page 408.) I enclose varieties of maize from Asa Gray. Pray do not thank me for trusting you; the thanks ought to go the other way. I felt a conviction after your first letter that you were a real lover of Natural History. If you can advance good evidence showing that bisexual plants are more variable than unisexual, it will be interesting. I shall be very glad to read the discussion which you are preparing. I admit as fully as any one can do that cross-impregnation is the great check to endless variability; but I am not sure that I understand your view. I do not believe that the structure of Primula has any necessary relation to a tendency to a dioecious structure, but seeing the difference in the fertility of the two forms, I felt bound unwillingly to admit that they might be a step towards dioeciousness; I allude to this subject in my Linum paper. (638/3. "Linn. Soc. Journal," 1863.) Thanks for your answers to my other queries. I forgot to say that I was at Kew the other day, and I find that they can give me capsules of several Vandeae. LETTER 639. TO J. SCOTT. Down, March 24th [1863]. Your letter, as every one you have written, has greatly interested me. If you can show that certain individual Passifloras, under certain known or unknown conditions of life, have stigmas capable of fertilisation by pollen from another species, or from another individual of its own species, yet not by its own individual pollen (its own individual pollen being proved to be good by its action on some other species), you will add a case of great interest to me; and which in my opinion would be quite worth your publication. (639/1. Cases nearly similar to those observed by Scott were recorded by Gartner and Kolreuter, but in these instances only certain individuals were self-impotent. In "Animals and Plants," Edition II., Volume II., page 114, where the phenomenon is fully discussed, Scott's observations ("Trans. Bot. Soc. Edin." 1863) are given as the earliest, except for one case recorded by Lecoq ("Fecondation," 1862). Interesting work was afterwards done by Hildebrand and Fritz Muller, as illustrated in many of the letters addressed to the latter.) I always imagined that such recorded cases must be due to unnatural conditions of life; and think I said so in the "Origin." (639/2. See "Origin of Species," Edition I., page 251, for Herbert's observations on self-impotence in Hippeastrum. In spite of the uniformness of the results obtained in many successive years, Darwin inferred that the plants must have been in an "unnatural state.") I am not sure that I understand your result, [nor] whether it means what I have above obscurely expressed. If you can prove the above, do publish; but if you will not publish I earnestly beg you to let me have the facts in detail; but you ought to publish, for I may not use the facts for years. I have been much interested by what you say on the rostellum exciting pollen to protrude tubes; but are you sure that the rostellum does excite them? Would not tubes protrude if placed on parts of column or base of petals, etc., near to the stigma? Please look at the "Cottage Gardener" (or "Journal of Horticulture") (639/3. "Journal of Horticulture" and "Cottage Gardener," March 31st, 1863. A short note describing Cruger's discovery of self-fertilisation in Cattleya, Epidendrum, etc., and referring to the work of "an excellent observer, Mr. J. Scott." Darwin adds that he is convinced that he has underrated the power of tropical orchids occasionally to produce seeds without the aid of insects.) to be published to-morrow week for letter of mine, in which I venture to quote you, and in which you will see a curious fact about unopened orchid flowers setting seed in West Indies. Dr. Cruger attributes protrusion of tubes to ants carrying stigmatic secretion to pollen (639/4. In Cruger's paper ("Linn. Soc. Journ." VIII., 1865; read March 3rd 1864) he speaks of the pollen-masses in situ being acted on by the stigmatic secretion, but no mention is made of the agency of ants. He describes the pollen-tubes descending "from the [pollen] masses still in situ down into the ovarian canal."); but this is mere hypothesis. Remember, pollen-tubes protrude within anther in Neottia nidus-avis. I did think it possible or probable that perfect fertilisation might have been effected through rostellum. What a curious case your Gongora must be: could you spare me one of the largest capsules? I want to estimate the number of seed, and try my hand if I can make them grow. This, however, is a foolish attempt, for Dr. Hooker, who was here a day or two ago, says they cannot at Calcutta, and yet imported species have seeded and have naturally spread on to the adjoining trees! Dr. Cruger thinks I am wrong about Catasetum: but I cannot understand his letter. He admits there are three forms in two species; and he speaks as if the sexes were separate in some and that others were hermaphrodites (639/5. Cruger ("Linn. Soc. Journal," VIII., page 127) says that the apparently hermaphrodite form is always sterile in Trinidad. Darwin modified his account in the second edition of the orchid book.); but I cannot understand what he means. He has seen lots of great humble-bees buzzing about the flowers with the pollinia sticking to their backs! Happy man!! I have the promise, but not yet surety, of some curious results with my homomorphic seedling cowslips: these have not followed the rule of Chinese Primula; homomorphic seedlings from short-styled parent have presented both forms, which disgusts me. You will see that I am better; but still I greatly fear that I must have a compulsory holiday. With sincere thanks and hearty admiration at your powers of observation... My poor P. scotica looks very sick which you so kindly sent me. (639/6. Sent by Scott, January 6th, 1863.) LETTER 640. TO J. SCOTT. April 12th [1863]. I really hardly know how to thank you enough for your very interesting letter. I shall certainly use all the facts which you have given me (in a condensed form) on the sterility of orchids in the work which I am now slowly preparing for publication. But why do you not publish these facts in a separate little paper? (640/1. See Letter 642, note, for reference to Scott's paper.) They seem to me well worth it, and you really ought to get your name known. I could equally well use them in my book. I earnestly hope that you will experiment on Passiflora, and let me give your results. Dr. A. Gray's observations were made loosely; he said in a letter he would attend this summer further to the case, which clearly surprised him much. I will say nothing about the rostellum, stigmatic utriculi, fertility of Acropera and Catasetum, for I am completely bewildered: it will rest with you to settle these points by your excellent observations and experiments. I must own I never could help doubting Dr. Hooker's case of the poppy. You may like to hear what I have seen this morning: I found (640/2. See Letter 658.) a primrose plant with flowers having three pistils, which when pulled asunder, without any tearing, allowed pollen to be placed on ovules. This I did with three flowers--pollen-tubes did not protrude after several days. But this day, the sixteenth (N.B.--primulas seem naturally slowly fertilised), I found many tubes protruded, and, what is very odd, they certainly seemed to have penetrated the coats of the ovules, but in no one instance the foramen of the ovule!! I mention this because it directly bears on your explanation of Dr. Cruger's case. (640/3. Cruger's case here referred to is doubtless the cleistogamic fertilisation of Epidendrum, etc. Scott discusses the question of self-fertilisation at great length in a letter to Darwin dated April, and obviously written in 1863. In Epidendrum he observed a viscid matter extending from the stigmatic chamber to the anther: pollen-tubes had protruded from the anther not only where it was in contact with the viscid matter, but also from the central part, and these spread "over the anterior surface of the rostellum downward into the stigma." Cruger believed the viscid matter reaching the anther was a necessary condition for the germination of the pollen-grains. Scott points out that the viscid matter is produced in large quantity only after the pollen-grains have penetrated the stigma, and that it is, in fact, a consequence, not a preliminary to fertilisation. He finally explains Cruger's case thus: "The greater humidity and equability of temperature consequent on such conditions [i.e. on the flowers being closed] is, I believe, the probable cause of these abnormally conditioned flowers so frequently fertilising themselves." Scott also calls attention to the danger of being deceived by fungal hyphae in observations on germination of pollen.) I believe that your explanation is right; I should never have thought of it; yet this was stupid of me, for I remember thinking that the almost closed imperfect flowers of Viola and Oxalis were related to the protrusion of the pollen-tubes. My case of the Aceras with the aborted labellum squeezed against stigma supports your view. (640/4. See "Fertilisation of Orchids," Edition II., page 258: the pollen germinated within the anther of a monstrous flower.) Dr. Cruger's notion about the ants was a simple conjecture. About cryptogamic filaments, remember Dr. C. says that the unopened flowers habitually set fruit. I think that you will change your views on the imperfect flowers of Viola and Oxalis... LETTER 641. (?) LETTER 642. TO J. SCOTT. May 2nd [1863]. I have left home for a fortnight to see if I can, with little hope, improve my health. The parcel of orchid pods, which you have so kindly sent me, has followed me. I am sure you will forgive the liberty which I take in returning you the postage stamps. I never heard of such a scheme as that you were compelled to practise to fertilise the Gongora! (642/1. See "Fertilisation of Orchids," Edition, II., page 169. "Mr. Scott tried repeatedly, but in vain, to force the pollen-masses into the stigma of Gongora atro-purpurea and truncata; but he readily fertilised them by cutting off the clinandrum and placing pollen-masses on the now exposed stigma.") It is a most curious problem what plan Nature follows in this genus and Acropera. (642/2. In the "Fertilisation of Orchids," Edition II., page 169, Darwin speculates as to the possible fertilisation of Acropera by an insect with pollen-masses adhering to the extremity of its abdomen. It would appear that this guess (which does not occur in the first edition) was made before he heard of Cruger's observation on the allied genus Gongora, which is visited by a bee with a long tongue, which projects, when not in use, beyond and above the tip of the abdomen. Cruger believes that this tongue is the pollinating agent. Cruger's account is in the "Journal of the Linn. Soc." VIII., 1865, page 130.) Some day I will try and estimate how many seeds there are in Gongora. I suppose and hope you have kept notes on all your observations on orchids, for, with my broken health and many other subjects, I do not know whether I shall ever have time to publish again; though I have a large collection of notes and facts ready. I think you show your wisdom in not wishing to publish too soon; a young author who publishes every trifle gets, sometimes unjustly, to be disregarded. I do not pretend to be much of a judge; but I can conscientiously say that I have never written one word to you on the merit of your letters that I do not fully believe in. Please remember that I should very much wish for a copy of your paper on sterility of individual orchids (642/3. "On the Individual Sterility and Cross-Impregnation of Certain Species of Oncidium." [Read June 2nd, 1864.] "Linn. Soc. Journal," VIII., 1865. This paper gives a full account of the self-sterility of Oncidium in cases where the pollen was efficient in fertilising other individuals of the same species and of distinct species. Some of the facts were given in Scott's paper, "Experiments on the Fertilisation of Orchids in the Royal Botanic Garden of Edinburgh," published in the "Proc. Bot. Soc. Edinb." 1863. It is probably to the latter paper that Darwin refers.) and on Drosera. (642/4. "Trans. Bot. Soc. Edinburgh," Volume VII.) Thanks for [note] about Campanula perfoliata. I have asked Asa Gray for seeds, to whom I have mentioned your observations on rostellum, and asked him to look closer to the case of Gymnadenia. (642/5. See "Fertilisation of Orchids," Edition II., page 68.) Let me hear about the sporting Imatophyllum if it flowers. Perhaps I have blundered about Primula; but certainly not about mere protrusion of pollen-tubes. I have been idly watching bees of several genera and diptera fertilising O. morio at this place, and it is a very pretty sight. I have confirmed in several ways the entire truth of my statement that there is no vestige of nectar in the spur; but the insects perforate the inner coat. This seems to me a curious little fact, which none of my reviewers have noticed. LETTER 643. TO J.D. HOOKER. Down, May 23rd [1863]. You can confer a real service on a good man, John Scott, the writer of the enclosed letter, by reading it and giving me your opinion. I assure [you] John Scott is a truly remarkable man. The part struck out is merely that he is not comfortable under Mr. McNab, and this part must be considered as private. Now the question is, what think you of the offer? Is expense of living high at Darjeeling? May I say it is healthy? Will he find the opportunity for experimental observations, which are a passion with him? It seems to me rather low pay. Will you advise me for him? I shall say that as far as experiments in hand at the Botanical Garden in Edinburgh are concerned, it would be a pity to hesitate to accept the offer. J. Scott is head of the propagating department. I know you will not grudge aiding by your advice a good man. I shall tell him that I have not the slightest power to aid him in any way for the appointment. I should think voyage out and home ought to be paid for? LETTER 644. TO JOHN SCOTT. Down, May 25th, 1863. Now for a few words on science. I do not think I could be mistaken about the stigma of Bolbophyllum (644/1. Bolbophyllum is remarkable for the closure of the stigmatic cavity which comes on after the flower has been open a little while, instead of after fertilisation, as in other genera. Darwin connects the fact with the "exposed condition of the whole flower."--"Fertilisation of Orchids," Edition II., page 137.); I had the plant alive from Kew, and watched many flowers. That is a most remarkable observation on foreign pollen emitting tubes, but not causing orifice to close (644/2. See Scott, "Bot. Soc. Edin." 1863, page 546, note. He applied pollinia from Cypripedium and Asclepias to flowers of Tricopilia tortilis; and though the pollen germinated, the stigmatic chamber remained open, yet it invariably closes eighteen hours after the application of its own pollen.); it would have been interesting to have observed how close an alliance of form would have acted on the orifice of the stigma. It will probably be so many years, if ever, [before] I work up my observations on Drosera, that I will not trouble you to send your paper, for I could not now find time to read it. If you have spare copy of your Orchid paper, please send it, but do not get a copy of the journal, for I can get one, and you must often want to buy books. Let me know when it is published. I have been glad to hear about Mercurialis, but I will not accept your offer of seed on account of time, time, time, and weak health. For the same reason I must give up Primula mollis. What a wonderful, indefatigable worker you are! You seem to have made a famous lot of interesting experiments. D. Beaton once wrote that no man could cross any species of Primula. You have apparently proved the contrary with a vengeance. Your numerous experiments seem very well selected, and you will exhaust the subject. Now when you have completed your work you should draw up a paper, well worth publishing, and give a list of all the dimorphic and non-dimorphic forms. I can give you, on the authority of Prof. Treviranus in "Bot. Zeitung," case of P. longiflora non-dimorphic. I am surprised at your cowslips in this state. Is it a common yellow cowslip? I have seen oxlips (which from some experiments I now look at as certainly natural hybrids) in same state. If you think the Botanical Society of Edinburgh would not do justice and publish your paper, send it to me to be communicated to the Linnean Society. I will delay my paper on successive dimorphic generations in Primula (644/3. Published in the "Journ. Linn. Soc." X., 1869 [1868].) till yours appears, so as in no way to interfere with your paper. Possibly my results may be hardly worth publishing, but I think they will; the seedlings from two successive homomorphic generations seem excessively sterile. I will keep this letter till I hear from Dr. Hooker. I shall be very glad if you try Passiflora. Your experiments on Primula seem so well chosen that whatever the result is they will be of value. But always remember that not one naturalist out of a dozen cares for really philosophical experiments. LETTER 645. TO J. SCOTT. Down, May 31st [1863]. I am unwell, and must write briefly. I am very much obliged for the "Courant." (645/1. The Edinburgh "Evening Courant" used to publish notices of the papers read at the Botanical Society of Edinburgh. The paper referred to here was Scott's on Oncidium.) The facts will be of highest use to me. I feel convinced that your paper will have permanent value. Your case seems excellently and carefully worked out. I agree that the alteration of title was unfortunate, but, after all, title does not signify very much. So few have attended to such points that I do not expect any criticism; but if so, I should think you had much better reply, but I could if you wished it much. I quite understand about the cases being individual sterility; so Gartner states it was with him. Would it be worth while to send a corrected copy of the "Courant" to the "Gardeners' Chronicle?" (645/2. An account of Scott's work appeared in the "Gardeners' Chronicle," June 13th, 1863, which is, at least partly, a reprint of the "Courant," since it contains the awkward sentence criticised by Darwin and referred to below. The title is "On the Fertilisation of Orchids," which was no doubt considered unfortunate as not suggesting the subject of the paper, and as being the same as that of Darwin's book.) I did not know that you had tried Lobelia fulgens: can you give me any particulars on the number of plants and kinds used, etc., that I may quote, as in a few days I shall be writing on this whole subject? No one will ever convince me that it is not a very important subject to philosophical naturalists. The Hibiscus seems a very curious case, and I agree with your remarks. You say that you are glad of criticisms (by the way avoid "former and latter," the reader is always forced to go back to look). I think you would have made the case more striking if you had first showed that the pollen of Oncidium sphacelatum was good; secondly, that the ovule was capable of fertilisation; and lastly, shown that the plant was impotent with its own pollen. "Impotence of organs capable of elimination"--capable here strictly refers to organs; you mean to impotence. To eliminate impotence is a curious expression; it is removing a non-existent quality. But style is a trifle compared with facts, and you are capable of writing well. I find it a good rule to imagine that I want to explain the case in as few and simple words as possible to one who knows nothing of the subject. (645/3. See Letter 151, Volume I.) I am tired. In my opinion you are an excellent observer. LETTER 646. TO J. SCOTT. Down, June 6th, 1863. I fear that you think that I have done more than I have with respect to Dr. Hooker. I did not feel that I had any right to ask him to remember you for a colonial appointment: all that I have done is to speak most highly of your scientific merits. Of course this may hereafter fructify. I really think you cannot go on better, for educational purposes, than you are now doing,--observing, thinking, and some reading beat, in my opinion, all systematic education. Do not despair about your style; your letters are excellently written, your scientific style is a little too ambitious. I never study style; all that I do is to try to get the subject as clear as I can in my own head, and express it in the commonest language which occurs to me. But I generally have to think a good deal before the simplest arrangement and words occur to me. Even with most of our best English writers, writing is slow work; it is a great evil, but there is no help for it. I am sure you have no cause to despair. I hope and suppose your sending a paper to the Linnean Society will not offend your Edinburgh friends; you might truly say that you sent the paper to me, and that (if it turns out so) I thought it worth communicating to the Linnean Society. I shall feel great interest in studying all your facts on Primula, when they are worked out and the seed counted. Size of capsules is often very deceptive. I am astonished how you can find time to make so many experiments. If you like to send me your paper tolerably well written, I would look it over and suggest any criticisms; but then this would cause you extra copying. Remember, however, that Lord Brougham habitually wrote everything important three times over. The cases of the Primulae which lose by variation their dimorphic characters seem to me very interesting. I find that the mid-styled (by variation) P. sinensis is more fertile with own pollen, even, than a heteromorphic union! If you have time it will be very good to experiment on Linum Lewisii. I wrote formerly to Asa Gray begging for seed. If you have time, I think experiments on any peloric flowers would be useful. I shall be sorry (and I am certain it is a mistake on the part of the Society) if your orchid paper is not printed in extenso. I am now at work compiling all such cases, and shall give a very full abstract of all your observations. I hope to add in autumn some from you on Passiflora. I would suggest to you the advantage, at present, of being very sparing in introducing theory in your papers (I formerly erred much in Geology in that way): LET THEORY GUIDE YOUR OBSERVATIONS, but till your reputation is well established be sparing in publishing theory. It makes persons doubt your observations. How rarely R. Brown ever indulged in theory: too seldom perhaps! Do not work too hard, and do not be discouraged because your work is not appreciated by the majority. LETTER 647. TO J. SCOTT. July 2nd [1863?] Many thanks for capsules. I would give table of the Auricula (647/1. In Scott's paper ("Linn. Soc. Journ." VIII.) many experiments on the Auricula are recorded.), especially owing to enclosed extract, which you can quote. Your facts about varying fertility of the primulas will be appreciated by but very few botanists; but I feel sure that the day will come when they will be valued. By no means modify even in the slightest degree any result. Accuracy is the soul of Natural History. It is hard to become accurate; he who modifies a hair's breadth will never be accurate. It is a golden rule, which I try to follow, to put every fact which is opposed to one's preconceived opinion in the strongest light. Absolute accuracy is the hardest merit to attain, and the highest merit. Any deviation is ruin. Sincere thanks for all your laborious trials on Passiflora. I am very busy, and have got two of my sons ill--I very much fear with scarlet fever; if so, no more work for me for some days or weeks. I feel greatly interested about your Primula cases. I think it much better to count seed than to weigh. I wish I had never weighed; counting is more accurate, though so troublesome. LETTER 648. TO J. SCOTT. Down, 25th [1863?] From what you say I looked again at "Bot. Zeitung." (648/1. "Ueber Dichogamie," "Bot. Zeit." January 1863.) Treviranus speaks of P. longiflora as short-styled, but this is evidently a slip of the pen, for further on, I see, he says the stigma always projects beyond anthers. Your experiments on coloured primroses will be most valuable if proved true. (648/2. The reference seems to be to Scott's observation that the variety rubra of the primrose was sterile when crossed with pollen from the common primrose. Darwin's caution to Scott was in some measure justified, for in his experiments on seedlings raised by self-fertilisation of the Edinburgh plants, he failed to confirm Scott's result. See "Forms of Flowers," Edition II., page 225. Scott's facts are in the "Journal Linn. Soc." VIII., page 97 (read February 4th, 1864).) I will advise to best of my power when I see MS. If evidence is not good I would recommend you, for your reputation's sake, to try them again. It is not likely that you will be anticipated, and it is a great thing to fully establish what in future time will be considered an important discovery (or rediscovery, for no one has noticed Gartner's facts). I will procure coloured primroses for next spring, but you may rely I will not publish before you. Do not work too hard to injure your health. I made some crosses between primrose and cowslip, and I send the results, which you may use if you like. But remember that I am not quite certain that I well castrated the short-styled primrose; I believe any castration would be superfluous, as I find all [these] plants sterile when insects are excluded. Be sure and save seed of the crossed differently coloured primroses or cowslips which produced least seed, to test the fertility of the quasi-hybrid seedlings. Gartner found the common primrose and cowslip very difficult to cross, but he knew nothing on dimorphism. I am sorry about delay [of] your orchid paper; I should be glad of abstract of your new observations of self-sterility in orchids, as I should probably use the new facts. There will be an important paper in September in "Annals and Magazine of Natural History," on ovules of orchids being formed after application of pollen, by Dr. F. Hildebrand of Bonn. (648/3. "Ann. Mag. Nat. Hist." XII., 1863, page 169. The paper was afterwards published in the "Bot. Zeitung," 1863.) LETTER 649. TO J. SCOTT. Down, November 7th [1863]. Every day that I could do anything, I have read a few pages of your paper, and have now finished it, and return it registered. (649/1. This refers to the MS. of Scott's paper on the Primulaceae, "Linn. Soc. Journ." VIII. [February 4th, 1864] 1865.) It has interested me deeply, and is, I am sure, an excellent memoir. It is well arranged, and in most parts well written. In the proof sheets you can correct a little with advantage. I have suggested a few alterations in pencil for your consideration, and have put in here and there a slip of paper. There will be no occasion to rewrite the paper--only, if you agree with me, to alter a few pages. When finished, return it to me, and I will with the highest satisfaction communicate it to the Linnean Society. I should be proud to be the author of the paper. I shall not have caused much delay, as the first meeting of the Society was on November 5th. When your Primula paper is finished, if you are so inclined, I should like to hear briefly about your Verbascum and Passiflora experiments. I tried Verbascum, and have got the pods, but do not know when I shall be able to see to the results. This subject might make another paper for you. I may add that Acropera luteola was fertilised by me, and had produced two fine pods. I congratulate you on your excellent paper. P.S.--In the summary to Primula paper can you conjecture what is the typical or parental form, i.e. equal, long or short styled? LETTER 650. TO J.D. HOOKER. Down, [January 24th, 1864]. (650/1. Darwin's interest in Scott's Primula work is shown by the following extracts from a letter to Hooker of January 24th, 1864, written, therefore, before the paper was read, and also by the subsequent correspondence with Hooker and Asa Gray. The first part of this letter illustrates Darwin's condition during a period of especially bad health.) As I do nothing all day I often get fidgety, and I now fancy that Charlie or some of your family [are] ill. When you have time let me have a short note to say how you all are. I have had some fearful sickness; but what a strange mechanism one's body is; yesterday, suddenly, I had a slight attack of rheumatism in my back, and I instantly became almost well, and so wonderfully strong that I walked to the hot-houses, which must be more than a hundred yards. I have sent Scott's paper to the Linnean Society; I feel sure it is really valuable, but I fear few will care about it. Remember my URGENT wish to be able to send the poor fellow a word of praise from any one. I have had work to get him to allow me to send the paper to the Linnean Society, even after it was written out. LETTER 651. TO J. SCOTT. Down, February 9th, 1864. (651/1. Scott's paper on Primulaceae was read at the Linnean Society on February 4th, 1864.) The President, Mr. Bentham, I presume, was so much struck by your paper that he sent me a message to know whether you would like to be elected an associate. As only one is elected annually, this is a decided honour. The enclosed list shows what respectable men are associates. I enclose the rules of admission. I feel sure that the rule that if no communication is received within three years the associate is considered to have voluntarily withdrawn, is by no means rigorously adhered to. Therefore, I advise you to accept; but of course the choice is quite free. You will see there is no payment. You had better write to me on this subject, as Dr. Hooker or I will propose you. LETTER 652. TO J.D. HOOKER. September 13th, 1864. I have been greatly interested by Scott's paper. I probably overrate it from caring for the subject, but it certainly seems to me one of the very most remarkable memoirs on such subjects which I have ever read. From the subject being complex, and the style in parts obscure, I suppose very few will read it. I think it ought to be noticed in the "Natural History Review," otherwise the more remarkable facts will never be known. Try and persuade Oliver to do it; with the summary it would not be troublesome. I would offer, but I have sworn to myself I will do nothing till my volume on "Variation under Domestication" is complete. I know you will not have time to read Scott, and therefore I will just point out the new and, as they seem to me, important points. Firstly, the red cowslip, losing its dimorphic structure and changing so extraordinarily in its great production of seed with its own pollen, especially being nearly sterile when fertilised by, or fertilising, the common cowslip. The analogous facts with red and white primrose. Secondly, the utter dissimilarity of action of the pollen of long- and short-styled form of one species in crossing with a distinct species. And many other points. Will you suggest to Oliver to review this paper? if he does so, and if it would be of any service to him, I would (as I have attended so much to these subjects) just indicate, with pages, leading and new points. I could send him, if he wishes, a separate and spare copy marked with pencil. LETTER 653. TO ASA GRAY. September 13th [1864]. (653/1. In September, 1864, Darwin wrote to Asa Gray describing Scott's work on the Primulaceae as:--) A paper which has interested me greatly by a gardener, John Scott; it seems to me a most remarkable production, though written rather obscurely in parts, but worth the labour of studying. I have just bethought me that for the chance of your noticing it in the "Journal," I will point out the new and very remarkable facts. I have paid the poor fellow's passage out to India, where I hope he will succeed, as he is a most laborious and able man, with the manners almost of a gentleman. (653/2. The following is an abstract of the paper which was enclosed in the letter to Asa Gray.) Pages 106-8. Red cowslip by variation has become non-dimorphic, and with this change of structure has become much more productive of seed than even the heteromorphic union of the common cowslip. Pages 91-2, similar case with Auricula; on the other hand a non-dimorphic variety of P. farinosa (page 115) is less fertile. These changes, or variations, in the generative system seem to me very remarkable. But far more remarkable is the fact that the red cowslip (pages 106-8) is very sterile when fertilising, or fertilised by the common cowslip. Here we have a new "physiological species." Analogous facts given (page 98) on the crossing of red and white primroses with common primroses. It is very curious that the two forms of the same species (pages 93, 94, 95, and 117) hybridise with extremely different degrees of facility with distinct species. He shows (page 94) that sometimes a cross with a quite distinct species yields more seed than a homomorphic union with own pollen. He shows (page 111) that of the two homomorphic unions possible with each dimorphic species the short-styled (as I stated) is the most sterile, and that my explanation is probably true. There is a good summary to the paper. LETTER 654. TO J.D. HOOKER. (654/1. The following letters to Hooker, April 1st, April 5th and May 22nd, refer to Darwin's scheme of employing Scott as an assistant at Down, and to Scott's appointment to the Botanic Garden at Calcutta.) Down, April 1st, 1864. I shall not at present allude to your very interesting letter (which as yet has been read to me only twice!), for I am full of a project which I much want you to consider. You will have seen Scott's note. He tells me he has no plans for the future. Thinking over all his letters, I believe he is a truly remarkable man. He is willing to follow suggestions, but has much originality in varying his experiments. I believe years may pass before another man appears fitted to investigate certain difficult and tedious points--viz. relative fertility of varieties of plants, including peloric and other monsters (already Scott has done excellent work on this head); and, secondly, whether a plant's own pollen is less effective than that of another individual. Now, if Scott is moderate in his wishes, I would pay him for a year or two to work and publish on these or other such subjects which might arise. But I dare not have him here, for it would quite overwork me. There would not be plants sufficient for his work, and it would probably be an injury to himself, as it would put him out of the way of getting a good situation. Now, I believe you have gardeners at Kew who work and learn there without pay. What do you think of having Scott there for a year or two to work and experiment? I can see enormous difficulties. In the first place you will not perhaps think the points indicated so highly important as I do. Secondly, he would require ground in some out-of-the-way place where the plants could be covered by a net, which would be unsightly. On the other hand, I presume you would like a series of memoirs published on work done at Kew, which I am fully convinced would have permanent value. It would, of course I conceive, be absolutely necessary that Scott should be under the regular orders of the superintendent. The only way I can fancy that it could be done would be to explain to the superintendent that I temporarily supported Scott solely for the sake of science, and appeal to his kindness to assist him. If you approved of having him (which I can see is improbable), and you simply ordered the superintendent to assist him, I believe everything would go to loggerheads. As for Scott himself, it would be of course an advantage to him to study the cultivation at Kew. You would get to know him, and if he really is a good man you could perhaps be able to recommend him to some situation at home or abroad. Pray turn this [over] in your mind. I have no idea whether Scott would like the place, but I can see that he has a burning zeal for science. He told me that his parents were in better circumstances, and that he chose a gardener's life solely as the best way of following science. I may just add that in his last letter he gives me the results of many experiments on different individuals of the same species of orchid, showing the most remarkable diversity in their sexual condition. It seems to me a grievous loss that such a man should have all his work cut short. Please remember that I know nothing of him excepting from his letters: these show remarkable talent, astonishing perseverance, much modesty, and what I admire, determined difference from me on many points. What will Sir William say? LETTER 655. TO J.D. HOOKER. Down, April 5th [1864]. I see my scheme for Scott has invincible difficulties, and I am very much obliged to you for explaining them at such length. If ever I get decently well, and Scott is free and willing, I will have him here for a couple of years to work out several problems, which otherwise would never be done. I cannot see what will become of the poor fellow. I enclose a little pamphlet from him, which I suppose is not of much scientific value, but is surprising as the work of a gardener. If you have time do just glance over it. I never heard anything so extraordinary as what you say about poisoning plants, etc. ...The post has just come in. Your interest about Scott is extraordinarily kind, and I thank you cordially. It seems absurd to say so, but I suspect that X is prejudiced against Scott because he partially supports my views. (655/1. In a letter to Scott (dated June 11th) Darwin warns him to keep his views "pretty quiet," and quotes Hooker's opinion that "if it is known that you agree at all with my views on species it is enough to make you unpopular in Edinburgh.") You must not trust my former letter about Clematis. I worked on too old a plant, and blundered. I have now gone over the work again. It is really curious that the stiff peduncles are acted upon by a bit of thread weighing .062 of a grain. Clematis glandulosa was a valuable present to me. My gardener showed it to me and said, "This is what they call a Clematis," evidently disbelieving it. So I put a little twig to the peduncle, and the next day my gardener said, "You see it is a Clematis, for it feels." That's the way we make out plants at Down. My dear old friend, God bless you! LETTER 656. TO J.D. HOOKER. [May 22nd, 1864]. What a good kind heart you have got. You cannot tell how your letter has pleased me. I will write to Scott and ask him if he chooses to go out and risk engagement. If he will not he must want all energy. He says himself he wants stoicism, and is too sensitive. I hope he may not want courage. I feel sure he is a remarkable man, with much good in him, but no doubt many errors and blemishes. I can vouch for his high intellect (in my judgment he is the best observer I ever came across); for his modesty, at least in correspondence; and there is something high-minded in his determination not to receive money from me. I shall ask him whether he can get a good character for probity and sobriety, and whether he can get aid from his relations for his voyage out. I will help, and, if necessary, pay the whole voyage, and give him enough to support him for some weeks at Calcutta. I will write when I hear from him. God bless you; you, who are so overworked, are most generous to take so much trouble about a man you have had nothing to do with. (656/1. Scott had left the Botanic Gardens at Edinburgh in March 1864, chagrined at what, justly or unjustly, he considered discouragement and slight. The Indian offer was most gladly and gratefully accepted.) LETTER 657. TO J. SCOTT. Down, November 1st, 1871. Dr. Hooker has forwarded to me your letter as the best and simplest plan of explaining affairs. I am sincerely grieved to hear of the pecuniary problem which you have undergone, but now fortunately passed. I assure you that I have never entertained any feelings in regard to you which you suppose. Please to remember that I distinctly stated that I did not consider the sum which I advanced as a loan, but as a gift; and surely there is nothing discreditable to you, under the circumstances, in receiving a gift from a rich man, as I am. Therefore I earnestly beg you to banish the whole subject from your mind, and begin laying up something for yourself in the future. I really cannot break my word and accept payment. Pray do not rob me of my small share in the credit of aiding to put the right man in the right place. You have done good work, and I am sure will do more; so let us never mention the subject again. I am, after many interruptions, at work again on my essay on Expression, which was written out once many months ago. I have found your remarks the best of all which have been sent me, and so I state. CHAPTER 2.XI.--BOTANY, 1863-1881. 2.XI.I. Miscellaneous, 1863-1866.--2.XI.II. Correspondence with Fritz Muller, 1865-1881.--2.XI.III. Miscellaneous, 1868-1881. 2.XI.I. MISCELLANEOUS, 1863-1866. LETTER 658. TO D. OLIVER. Down [April, 1863]. (658/1. The following letter illustrates the truth of Sir W. Thiselton-Dyer's remark that Darwin was never "afraid of his facts." (658/2. "Charles Darwin" (Nature Series), 1882, page 43.) The entrance of pollen-tubes into the nucellus by the chalaza, instead of through the micropyle, was first fully demonstrated by Treub in his paper "Sur les Casuarinees et leur place dans le Systeme naturel," published in the "Ann. Jard. Bot. Buitenzorg," X., 1891. Two years later Miss Benson gave an account of a similar phenomenon in certain Amentiferae ("Trans. Linn. Soc." 1888-94, page 409). This chalazogamic method of fertilisation has since been recognised in other flowering plants, but not, so far as we are aware, in the genus Primula.) It is a shame to trouble [you], but will you tell me whether the ovule of Primula is "anatropal," nearly as figured by Gray, page 123, "Lessons in Botany," or rather more tending to "amphitropal"? I never looked at such a point before. Why I am curious to know is because I put pollen into the ovarium of monstrous primroses, and now, after sixteen days, and not before (the length of time agrees with slowness of natural impregnation), I find abundance of pollen-tubes emitted, which cling firmly to the ovules, and, I think I may confidently state, penetrate the ovule. But here is an odd thing: they never once enter at (what I suppose to be) the "orifice," but generally at the chalaza...Do you know how pollen-tubes go naturally in Primula? Do they run down walls of ovarium, and then turn up the placenta, and so debouch near the "orifices" of the ovules? If you thought it worth while to examine ovules, I would see if there are more monstrous flowers, and put pollen into the ovarium, and send you the flowers in fourteen or fifteen days afterwards. But it is rather troublesome. I would not do it unless you cared to examine the ovules. Like a foolish and idle man, I have wasted a whole morning over them... In two ovules there was an odd appearance, as if the outer coat of ovule at the chalaza end (if I understand the ovule) had naturally opened or withered where most of the pollen-tubes seemed to penetrate, which made me at first think this was a widely open foramen. I wonder whether the ovules could be thus fertilised? LETTER 659. TO D. OLIVER. Down [April, 1863]. Many thanks about the Primula. I see that I was pretty right about the ovules. I have been thinking that the apparent opening at the chalaza end must have been withering or perhaps gnawing by some very minute insects, as the ovarium is open at the upper end. If I have time I will have another look at pollen-tubes, as, from what you say, they ought to find their way to the micropyle. But ovules to me are far more troublesome to dissect than animal tissue; they are so soft, and muddy the water. LETTER 660. TO MAXWELL MASTERS. Down, April 6th [1863]. I have been very glad to read your paper on Peloria. (660/1. "On the Existence of Two Forms of Peloria." "Natural History Review," April, 1863, page 258.) For the mere chance of the following case being new I send it. A plant which I purchased as Corydalis tuberosa has, as you know, one nectary--short, white, and without nectar; the pistil is bowed towards the true nectary; and the hood formed by the inner petals slips off towards the opposite side (all adaptations to insect agency, like many other pretty ones in this family). Now on my plants there are several flowers (the fertility of which I will observe) with both nectaries equal and purple and secreting nectar; the pistil is straight, and the hood slips off either way. In short, these flowers have the exact structure of Dielytra and Adlumia. Seeing this, I must look at the case as one of reversion; though it is one of the spreading of irregularity to two sides. As columbine [Aquilegia] has all petals, etc., irregular, and as monkshood [Aconitum] has two petals irregular, may not the case given by Seringe, and referred to [by] you (660/2. "Seringe describes and figures a flower [of Aconitum] wherein all the sepals were helmet-shaped," and the petals similarly affected. Maxwell Masters, op. cit., page 260.), by you be looked at as reversion to the columbine state? Would it be too bold to suppose that some ancient Linaria, or allied form, and some ancient Viola, had all petals spur-shaped, and that all cases of "irregular peloria" in these genera are reversions to such imaginary ancient form? (660/3. "'Regular or Congenital Peloria' would include those flowers which, contrary to their usual habit, retain throughout the whole of their growth their primordial regularity of form and equality of proportion. 'Irregular or Acquired Peloria,' on the other hand, would include those flowers in which the irregularity of growth that ordinarily characterises some portions of the corolla is manifested in all of them." Maxwell Masters, loc. cit.) It seems to me, in my ignorance, that it would be advantageous to consider the two forms of Peloria WHEN OCCURRING IN THE VERY SAME SPECIES as probably due to the same general law--viz., one as reversion to very early state, and the other as reversion to a later state when all the petals were irregularly formed. This seems at least to me a priori a more probable view than to look at one form of Peloria as due to reversion and the other as something distinct. (660/4. See Maxwell Masters, "Vegetable Teratology," 1869, page 235; "Variation of Animals and Plants," Edition II., Volume II., page 33.) What do you think of this notion? LETTER 661. TO P.H. GOSSE. (661/1. The following was written in reply to Mr. Gosse's letter of May 30th asking for a solution of his difficulties in fertilising Stanhopea. It is reprinted by the kind permission of Mr. Edmund Gosse from his delightful book, the "Life of Philip Henry Gosse," London, 1890, page 299.) Down, June 2nd, 1863. It would give me real pleasure to resolve your doubts, but I cannot. I can give only suspicions and my grounds for them. I should think the non-viscidity of the stigmatic hollow was due to the plant not living under its natural conditions. Please see what I have said on Acropera. An excellent observer, Mr. J. Scott, of the Botanical Gardens, Edinburgh, finds all that I say accurate, but, nothing daunted, he with the knife enlarged the orifice and forced in pollen-masses; or he simply stuck them into the contracted orifice without coming into contact with the stigmatic surface, which is hardly at all viscid, when, lo and behold, pollen-tubes were emitted and fine seed capsules obtained. This was effected with Acropera Loddigesii; but I have no doubt that I have blundered badly about A. luteola. I mention all this because, as Mr. Scott remarks, as the plant is in our hot-houses, it is quite incredible it ever could be fertilised in its native land. The whole case is an utter enigma to me. Probably you are aware that there are cases (and it is one of the oddest facts in Physiology) of plants which, under culture, have their sexual functions in so strange a condition, that though their pollen and ovules are in a sound state and can fertilise and be fertilised by distinct but allied species, they cannot fertilise themselves. Now, Mr. Scott has found this the case with certain orchids, which again shows sexual disturbance. He had read a paper at the Botanical Society of Edinburgh, and I daresay an abstract which I have seen will appear in the "Gardeners' Chronicle"; but blunders have crept in in copying, and parts are barely intelligible. How insects act with your Stanhopea I will not pretend to conjecture. In many cases I believe the acutest man could not conjecture without seeing the insect at work. I could name common English plants in this predicament. But the musk-orchis [Herminium monorchis] is a case in point. Since publishing, my son and myself have watched the plant and seen the pollinia removed, and where do you think they invariably adhere in dozens of specimens?--always to the joint of the femur with the trochanter of the first pair of legs, and nowhere else. When one sees such adaptation as this, it would be hopeless to conjecture on the Stanhopea till we know what insect visits it. I have fully proved that my strong suspicion was correct that with many of our English orchids no nectar is excreted, but that insects penetrate the tissues for it. So I expect it must be with many foreign species. I forgot to say that if you find that you cannot fertilise any of your exotics, take pollen from some allied form, and it is quite probable that will succeed. Will you have the kindness to look occasionally at your bee-Ophrys near Torquay, and see whether pollinia are ever removed? It is my greatest puzzle. Please read what I have said on it, and on O. arachnites. I have since proved that the account of the latter is correct. I wish I could have given you better information. P.S.--If the Flowers of the Stanhopea are not too old, remove pollen-masses from their pedicels, and stick them with a little liquid pure gum to the stigmatic cavity. After the case of the Acropera, no one can dare positively say that they would not act. LETTER 662. TO J.D. HOOKER. Down, Saturday, 5th [December 1863]. I am very glad that this will reach you at Kew. You will then get rest, and I do hope some lull in anxiety and fear. Nothing is so dreadful in this life as fear; it still sickens me when I cannot help remembering some of the many illnesses our children have endured. My father, who was a sceptical man, was convinced that he had distinctly traced several cases of scarlet fever to handling letters from convalescents. The vases (662/1. Probably Wedgwood ware.) did come from my sister Susan. She is recovering, and was much pleased to hear that you liked them; I have now sent one of your notes to her, in which you speak of them as "enchanting," etc. I have had a bad spell--vomiting, every day for eleven days, and some days many times after every meal. It is astonishing the degree to which I keep up some strength. Dr. Brinton was here two days ago, and says he sees no reason [why] I may not recover my former degree of health. I should like to live to do a little more work, and often I feel sure I shall, and then again I feel that my tether is run out. Your Hastings note, my dear old fellow, was a Copley Medal to me and more than a Copley Medal: not but what I know well that you overrate what I have been able to do. (662/2. The proposal to give the medal to Darwin failed in 1863, but his friends were successful in 1864: see "Life and Letters," III., page 28.) Now that I am disabled, I feel more than ever what a pleasure observing and making out little difficulties is. By the way, here is a very little fact which may interest you. A partridge foot is described in "Proc. Zoolog. Soc." with a huge ball of earth attached to it as hard as rock. (662/3. "Proc. Zool. Soc." 1863, page 127, by Prof. Newton, who sent the foot to Darwin: see "Origin," Edition VI., page 328.) Bird killed in 1860. Leg has been sent me, and I find it diseased, and no doubt the exudation caused earth to accumulate; now already thirty-two plants have come up from this ball of earth. By Jove! I must write no more. Good-bye, my best of friends. There is an Italian edition of the "Origin" preparing. This makes the fifth foreign edition--i.e. in five foreign countries. Owen will not be right in telling Longmans that the book would be utterly forgotten in ten years. Hurrah! LETTER 663. TO D. OLIVER. Down, February 17th [1864]. Many thanks for the Epacrids, which I have kept, as they will interest me when able to look through the microscope. Dr. Cruger has sent me the enclosed paper, with power to do what I think fit with it. He would evidently prefer it to appear in the "Nat. Hist. Review." Please read it, and let me have your decision pretty soon. Some germanisms must be corrected; whether woodcuts are necessary I have not been able to pay attention enough to decide. If you refuse, please send it to the Linnean Society as communicated by me. (663/1. H. Cruger's "A Few Notes on the Fecundation of Orchids, etc." [Read March, 1864.] "Linn. Soc. Journ." VIII., 1864-5, page 127.) The paper has interested me extremely, and I shall have no peace till I have a good boast. The sexes are separate in Catasetum, which is a wonderful relief to me, as I have had two or three letters saying that the male C. tridentatum seeds. (663/2. See footnote Letter 608 on the sexual relation between the three forms known as Catasetum tridentatum, Monacanthus viridis, and Myanthus barbatus. For further details see Darwin, "Linn. Soc. Journ." VI., 1862, page 151, and "Fertilisation of Orchids," Edition II., page 196.) It is pretty clear to me that two or three forms are confounded under this name. Observe how curiously nearly perfect the pollen of the female is, according to Cruger,--certainly more perfect than the pollen from the Guyana species described by me. I was right in the manner in which the pollen adheres to the hairy back of the humble-bee, and hence the force of the ejection of the pollina. (663/3. This view was given in "Fertilisation of Orchids," Edition I., 1862, page 230.) I am still more pleased that I was right about insects gnawing the fleshy labellum. This is important, as it explains all the astounding projections on the labellum of Oncidium, Phalaenopsis, etc. Excuse all my boasting. It is the best medicine for my stomach. Tell me whether you mean to take up orchids, as Hooker said you were thinking of doing. Do you know Coryanthes, with its wonderful basket of water? See what Cruger says about it. It beats everything in orchids. (663/4. For Coryanthes see "Fertilisation of Orchids," Edition II., page 173.) LETTER 664. TO J.D. HOOKER. Down [September 13th, 1864]. Thanks for your note of the 5th. You think much and greatly too much of me and my doings; but this is pleasant, for you have represented for many years the whole great public to me. I have read with interest Bentham's address on hybridism. I am glad that he is cautious about Naudin's view, for I cannot think that it will hold. (664/1. C. Naudin's "Nouvelles Recherches sur l'Hydridite dans les Vegetaux." The complete paper, with coloured plates, was presented to the Academy in 1861, and published in full in the "Nouvelles Archives de Museum d'Hist. Nat." Volume I., 1865, page 25. The second part only appeared in the "Ann. Sci. Nat." XIX., 1863. Mr. Bentham's address dealing with hybridism is in "Proc. Linn. Soc." VIII., 1864, page ix. A review of Naudin is given in the "Natural History Review," 1864, page 50. Naudin's paper is of much interest, as containing a mechanical theory of reproduction of the same general character as that of pangenesis. In the "Variation of Animals and Plants," Edition II., Volume II., page 395, Darwin states that in his treatment of hybridism in terms of gemmules he is practically following Naudin's treatment of the same theme in terms of "essences." Naudin, however, does not clearly distinguish between hybrid and pure gemmules, and makes the assumption that the hybrid or mixed essences tend constantly to dissociate into pure parental essences, and thus lead to reversion. It is to this view that Darwin refers when he says that Naudin's view throws no light on the reversion to long-lost characters. His own attempt at explaining this fact occurs in "Variation under Domestication," II., Edition II., page 395. Mr. Bateson ("Mendel's Principle of Heredity," Cambridge, 1902, page 38) says: "Naudin clearly enuntiated what we shall henceforth know as the Mendelian conception of the dissociation of characters of cross-breds in the formation of the germ-cells, though apparently he never developed this conception." It is remarkable that, as far as we know, Darwin never in any way came across Mendel's work. One of Darwin's correspondents, however, the late Mr. T. Laxton, of Stamford, was close on the trail of Mendelian principle. Mr. Bateson writes (op. cit., page 181): "Had he [Laxton] with his other gifts combined this penetration which detects a great principle hidden in the thin mist of 'exceptions,' we should have been able to claim for him that honour which must ever be Mendel's in the history of discovery.") The tendency of hybrids to revert to either parent is part of a wider law (which I am fully convinced that I can show experimentally), namely, that crossing races as well as species tends to bring back characters which existed in progenitors hundreds and thousands of generations ago. Why this should be so, God knows. But Naudin's view throws no light, that I can see, on this reversion of long-lost characters. I wish the Ray Society would translate Gartner's "Bastarderzeugung"; it contains more valuable matter than all other writers put together, and would do great service if better known. (664/2. "Versuche uber die Bastarderzeugung im Pflanzenreich": Stuttgart, 1849.) LETTER 665. TO T.H. HUXLEY. (665/1. Mr. Huxley had doubted the accuracy of observations on Catasetum published in the "Fertilisation of Orchids." In what formed the postscript to the following letter, Darwin wrote: "I have had more Catasetums,--all right, you audacious 'caviller.'") Down, October 31st [1862]. In a little book, just published, called the "Three Barriers" (a theological hash of old abuse of me), Owen gives to the author a new resume of his brain doctrine; and I thought you would like to hear of this. He ends with a delightful sentence. "No science affords more scope or easier ground for the caviller and controversialist; and these do good by preventing scholars from giving more force to generalisations than the master propounding them does, or meant his readers or hearers to give." You will blush with pleasure to hear that you are of some use to the master. LETTER 666. TO J.D. HOOKER. [February, 1864?] I shall write again. I write now merely to ask, if you have Naravelia (666/1. Ranunculaceae.) (the Clematis-like plant told me by Oliver), to try and propagate me a plant at once. Have you Clematis cirrhosa? It will amuse me to tell you why Clematis interests me, and why I should so very much like to have Naravelia. The leaves of Clematis have no spontaneous movement, nor have the internodes; but when by growth the peduncles of leaves are brought into contact with any object, they bend and catch hold. The slightest stimulus suffices, even a bit of cotton thread a few inches long; but the stimulus must be applied during six or twelve hours, and when the peduncles once bend, though the touching object be removed, they never get straight again. Now mark the difference in another leaf-climber--viz., Tropaeolum: here the young internodes revolve day and night, and the peduncles of the leaves are thus brought into contact with an object, and the slightest momentary touch causes them to bend in any direction and catch the object, but as the axis revolves they must be often dragged away without catching, and then the peduncles straighten themselves again, and are again ready to catch. So that the nervous system of Clematis feels only a prolonged touch--that of Tropaeolum a momentary touch: the peduncles of the latter recover their original position, but Clematis, as it comes into contact by growth with fixed objects, has no occasion to recover its position, and cannot do so. You did send me Flagellaria, but most unfortunately young plants do not have tendrils, and I fear my plant will not get them for another year, and this I much regret, as these leaf-tendrils seem very curious, and in Gloriosa I could not make out the action, but I have now a young plant of Gloriosa growing up (as yet with simple leaves) which I hope to make out. Thank Oliver for decisive answer about tendrils of vines. It is very strange that tendrils formed of modified leaves and branches should agree in all their four highly remarkable properties. I can show a beautiful gradation by which LEAVES produce tendrils, but how the axis passes into a tendril utterly puzzles me. I would give a guinea if vine-tednrils could be found to be leaves. (666/2. It is an interesting fact that Darwin's work on climbing plants was well advanced before he discovered the existence of the works of Palm, Mohl, and Dutrochet on this subject. On March 22nd, 1864, he wrote to Hooker:--"You quite overrate my tendril work, and there is no occasion to plague myself about priority." In June he speaks of having read "two German books, and all, I believe, that has been written on climbers, and it has stirred me up to find that I have a good deal of new matter.") LETTER 667. TO J.D. HOOKER. Down, June 2nd [1864]. You once offered me a Combretum. (667/1. The two forms of shoot in C. argenteum are described in "Climbing Plants," page 41.) I having C. purpureum, out of modesty like an ass refused. Can you now send me a plant? I have a sudden access of furor about climbers. Do you grow Adlumia cirrhosa? Your seed did not germinate with me. Could you have a seedling dug up and potted? I want it fearfully, for it is a leaf-climber, and therefore sacred. I have some hopes of getting Adlumia, for I used to grow the plant, and seedlings have often come up, and we are now potting all minute reddish-coloured weeds. (667/2. We believe that the Adlumia which came up year by year in flower boxes in the Down verandah grew from seed supplied by Asa Gray.) I have just got a plant with sensitive axis, quite a new case; and tell Oliver I now do not care at all how many tendrils he makes axial, which at one time was a cruel torture to me. LETTER 668. TO J.D. HOOKER. Down, November 3rd [1864]. Many thanks for your splendid long letter. But first for business. Please look carefully at the enclosed specimen of Dicentra thalictriformis, and throw away. (668/1. Dicentra thalictrifolia, a Himalayan species of Fumariaceae, with leaf-tendrils.) When the plant was young I concluded certainly that the tendrils were axial, or modified branches, which Mohl says is the case with some Fumariaceae. (668/2. "Ueber den Bau und das Winden der Ranken und Schlingpflanzen. Eine gekronte Preisschrift," 4to, Tubingen, 1827. At page 43 Mohl describes the tips of the branches of Fumaria [Corydalis] clavicualta as being developed into tendrils, as well as the leaves. For this reason Darwin placed the plant among the tendril-bearers rather than among the true leaf-climbers: see "Climbing Plants," Edition II., 1875, page 121.) You looked at them here and agreed. But now the plant is old, what I thought was a branch with two leaves and ending in a tendril looks like a gigantic leaf with two compound leaflets, and the terminal part converted into a tendril. For I see buds in the fork between supposed branch and main stem. Pray look carefully--you know I am profoundly ignorant--and save me from a horrid mistake. LETTER 669. TO J.D. HOOKER. (669/1. The following is interesting, as containing a foreshadowing of the chemotaxis of antherozoids which was shown to exist by Pfeffer in 1881: see "Untersuchungen aus dem botanischen Institut zu Tubingen," Volume I., page 363. There are several papers by H.J. Carter on the reproduction of the lower organisms in the "Annals and Magazine of Natural History" between 1855 and 1865.) Down, Sunday, 22nd, and Saturday, 28th [October, 1865]. I have been wading through the "Annals and Mag. of N. History." for last ten years, and have been interested by several papers, chiefly, however, translations; but none have interested me more than Carter's on lower vegetables, infusoria, and protozoa. Is he as good a workman as he appears? for if so he would deserve a Royal medal. I know it is not new; but how wonderful his account of the spermatozoa of some dioecious alga or conferva, swimming and finding the minute micropyle in a distinct plant, and forcing its way in! Why, these zoospores must possess some sort of organ of sense to guide their locomotive powers to the small micropyle; and does not this necessarily imply something like a nervous system, in the same way as complemental male cirripedes have organs of sense and locomotion, and nothing else but a sack of spermatozoa? LETTER 670. TO F. HILDEBRAND. May 16th, 1866. Since writing to you before, I have read your admirable memoir on Salvia (670/1. "Pringsheim's Jahrbucher," Volume IV., 1866.), and it has interested me almost as much as when I first investigated the structure of orchids. Your paper illustrates several points in my "Origin of Species," especially the transition of organs. Knowing only two or three species in the genus, I had often marvelled how one cell of the anther could have been transformed into the moveable plate or spoon; and how well you show the gradations. But I am surprised that you did not more strongly insist on this point. I shall be still more surprised if you do not ultimately come to the same belief with me, as shown by so many beautiful contrivances,--that all plants require, from some unknown cause, to be occasionally fertilised by pollen from a distinct individual. (PLATE: FRITZ MULLER.) 2.XI.II. CORRESPONDENCE WITH FRITZ MULLER, 1865-1881. (671/1. The letters from Darwin to Muller are given as a separate group, instead of in chronological sequence with the other botanical letters, as better illustrating the uninterrupted friendship and scientific comradeship of the two naturalists.) LETTER 671. TO F. MULLER. Down, October 17th [1865]. I received about a fortnight ago your second letter on climbing plants, dated August 31st. It has greatly interested me, and it corrects and fills up a great hiatus in my paper. As I thought you could not object, I am having your letter copied, and will send the paper to the Linnean Society. (671/2. "Notes on some of the Climbing Plants near Desterro" [1865], "Linn. Soc. Journ." IX., 1867.) I have slightly modified the arrangement of some parts and altered only a few words, as you write as good English as an Englishman. I do not quite understand your account of the arrangement of the leaves of Strychnos, and I think you use the word "bracteae" differently to what English authors do; therefore I will get Dr. Hooker to look over your paper. I cannot, of course, say whether the Linnean Society will publish your paper; but I am sure it ought to do so. As the Society is rather poor, I fear that it will give only a few woodcuts from your truly admirable sketches. LETTER 672. TO F. MULLER. (672/1. In Darwin's book on Climbing Plants, 1875 (672/2. First given as a paper before the Linnean Society, and published in the "Linn. Soc. Journ." Volume IX.,), he wrote (page 205): "The conclusion is forced on our minds that the capacity of revolving, on which most climbing plants depend, is inherent, though undeveloped, in almost every plant in the vegetable Kingdom"--a conclusion which was verified in the "Power of Movement in Plants." The present letter is interesting in referring to Fritz Muller's observations on the "revolving nutation," or circumnutation of Alisma macrophylla and Linum usitatissimum, the latter fact having been discovered by F. Muller's daughter Rosa. This was probably the earliest observation on the circumnutation of a non-climbing plant, and Muller, in a paper dated 1868, and published in Volume V. of the "Jenaische Zeitschrift," page 133, calls attention to its importance in relation to the evolution of the habit of climbing. The present letter was probably written in 1865, since it refers to Muller's paper read before the Linnean Soc. on December 7th, 1865. If so, the facts on circumnutation must have been communicated to Darwin some years before their publication in the "Jenaische Zeitschrift.") Down, December 9th [1865]. I have received your interesting letter of October 10th, with its new facts on branch-tendrils. If the Linnean Society publishes your paper (672/3. Ibid., 1867, page 344.), as I am sure it ought to do, I will append a note with some of these new facts. I forwarded immediately your MS. to Professor Max Schultze, but I did not read it, for German handwriting utterly puzzles me, and I am so weak, I am capable of no exertion. I took the liberty, however, of asking him to send me a copy, if separate ones are printed, and I reminded him about the Sponge paper. You will have received before this my book on orchids, and I wish I had known that you would have preferred the English edition. Should the German edition fail to reach you, I will send an English one. That is a curious observation of your daughter about the movement of the apex of the stem of Linum, and would, I think, be worth following out. (672/4. F. Muller, "Jenaische Zeitschrift," Bd. V., page 137. Here, also, are described the movements of Alisma.) I suspect many plants move a little, following the sun; but all do not, for I have watched some pretty carefully. I can give you no zoological news, for I live the life of the most secluded hermit. I occasionally hear from Ernest Hackel, who seems as determined as you are to work out the subject of the change of species. You will have seen his curious paper on certain medusae reproducing themselves by seminal generation at two periods of growth. (672/5. On April 3rd, 1868, Darwin wrote to F. Muller: "Your diagram of the movements of the flower-peduncle of the Alisma is extremely curious. I suppose the movement is of no service to the plant, but shows how easily the species might be converted into a climber. Does it bend through irritability when rubbed?" LETTER 673. TO F. MULLER. Down, September 25th [1866]. I have just received your letter of August 2nd, and am, as usual, astonished at the number of interesting points which you observe. It is quite curious how, by coincidence, you have been observing the same subjects that have lately interested me. Your case of the Notylia is quite new to me (673/1. See F. Muller, "Bot. Zeitung," 1868, page 630; "Fertilisation of Orchids," Edition II., page 171.); but it seems analogous with that of Acropera, about the sexes of which I blundered greatly in my book. I have got an Acropera now in flower, and have no doubt that some insect, with a tuft of hairs on its tail, removes by the tuft, the pollinia, and inserts the little viscid cap and the long pedicel into the narrow stigmatic cavity, and leaves it there with the pollen-masses in close contact with, but not inserted into, the stigmatic cavity. I find I can thus fertilise the flowers, and so I can with Stanhopea, and I suspect that this is the case with your Notylia. But I have lately had an orchis in flower--viz. Acineta, which I could not anyhow fertilise. Dr. Hildebrand lately wrote a paper (673/2. "Bot. Zeitung," 1863, 1865.) showing that with some orchids the ovules are not mature and are not fertilised until months after the pollen-tubes have penetrated the column, and you have independently observed the same fact, which I never suspected in the case of Acropera. The column of such orchids must act almost like the spermatheca of insects. Your orchis with two leaf-like stigmas is new to me; but I feel guilty at your wasting your valuable time in making such beautiful drawings for my amusement. Your observations on those plants being sterile which grow separately, or flower earlier than others, are very interesting to me: they would be worth experimenting on with other individuals. I shall give in my next book several cases of individual plants being sterile with their own pollen. I have actually got on my list Eschscholtzia (673/3. See "Animals and Plants," II., Edition II., page 118.) for fertilising with its own pollen, though I did not suspect it would prove sterile, and I will try next summer. My object is to compare the rate of growth of plants raised from seed fertilised by pollen from the same flower and by pollen from a distinct plant, and I think from what I have seen I shall arrive at interesting results. Dr. Hildebrand has lately described a curious case of Corydalis cava which is quite sterile with its own pollen, but fertile with pollen of any other individual plant of the species. (673/4. "International Horticultural Congress," London, 1866, quoted in "Variation of Animals and Plants," Edition II., Volume II., page 113.) What I meant in my paper on Linum about plants being dimorphic in function alone, was that they should be divided into two equal bodies functionally but not structurally different. I have been much interested by what you say on seeds which adhere to the valves being rendered conspicuous. You will see in the new edition of the "Origin" (673/5. "Origin of Species," Edition IV., 1866, page 238. A discussion on the origin of beauty, including the bright colours of flowers and fruits.) why I have alluded to the beauty and bright colours of fruit; after writing this it troubled me that I remembered to have seen brilliantly coloured seed, and your view occurred to me. There is a species of peony in which the inside of the pod is crimson and the seeds dark purple. I had asked a friend to send me some of these seeds, to see if they were covered with anything which could prove attractive to birds. I received some seeds the day after receiving your letter, and I must own that the fleshy covering is so thin that I can hardly believe it would lead birds to devour them; and so it was in an analogous case with Passiflora gracilis. How is this in the cases mentioned by you? The whole case seems to me rather a striking one. I wish I had heard of Mikania being a leaf-climber before your paper was printed (673/6. See "Climbing Plants (3rd thousand, 1882), page 116. Mikania and Mutisia both belong to the Compositae. Mikania scandens is a twining plant: it is another species which, by its leaf-climbing habit, supplies a transition to the tendril-climber Mutisia. F. Muller's paper is in "Linn. Soc. Journ." IX., page 344.), for we thus get a good gradation from M. scandens to Mutisia, with its little modified, leaf-like tendrils. I am glad to hear that you can confirm (but render still more wonderful) Hackel's most interesting case of Linope. Huxley told me that he thought the case would somehow be explained away. LETTER 674. TO F. MULLER. Down [Received January 24th, 1867]. I have so much to thank you for that I hardly know how to begin. I have received the bulbils of Oxalis, and your most interesting letter of October 1st. I planted half the bulbs, and will plant the other half in the spring. The case seems to me very curious, and until trying some experiments in crossing I can form no conjecture what the abortion of the stamens in so irregular a manner can signify. But I fear from what you say the plant will prove sterile, like so many others which increase largely by buds of various kinds. Since I asked you about Oxalis, Dr. Hildebrand has published a paper showing that a great number of species are trimorphic, like Lythrum, but he has tried hardly any experiments. (674/1. Hildebrand's work, published in the "Monatsb. d. Akad. d. Wiss. Berlin," 1866, was chiefly on herbarium specimens. His experimental work was published in the "Bot. Zeitung," 1871.) I am particularly obliged for the information and specimens of Cordia (674/2. Cordiaceae: probably dimorphic.), and shall be most grateful for seed. I have not heard of any dimorphic species in this family. Hardly anything in your letter interested me so much as your account and drawing of the valves of the pod of one of the Mimoseae with the really beautiful seeds. I will send some of these seeds to Kew to be planted. But these seeds seem to me to offer a very great difficulty. They do not seem hard enough to resist the triturating power of the gizzard of a gallinaceous bird, though they must resist that of some other birds; for the skin is as hard as ivory. I presume that these seeds cannot be covered with any attractive pulp? I soaked one of the seeds for ten hours in warm water, which became only very slightly mucilaginous. I think I will try whether they will pass through a fowl uninjured. (674/3. The seeds proved to be those of Adenanthera pavonina. The solution of the difficulty is given in the following extract from a letter to Muller, March 2nd, 1867: "I wrote to India on the subject, and I hear from Mr. J. Scott that parrots are eager for the seeds, and, wonderful as the fact is, can split them open with their beaks; they first collect a large number in their beaks, and then settle themselves to split them, and in doing so drop many; thus I have no doubt they are disseminated, on the same principle that the acorns of our oaks are most widely disseminated." Possibly a similar explanation may hold good for the brightly coloured seeds of Abrus precatorius.) I hope you will observe whether any bird devours them; and could you get any young man to shoot some and observe whether the seeds are found low down in the intestines? It would be well worth while to plant such seeds with undigested seeds for comparison. An opponent of ours might make a capital case against us by saying that here beautiful pods and seeds have been formed not for the good of the plant, but for the good of birds alone. These seeds would make a beautiful bracelet for one of my daughters, if I had enough. I may just mention that Euonymus europoeus is a case in point: the seeds are coated by a thin orange layer, which I find is sufficient to cause them to be devoured by birds. I have received your paper on Martha [Posoqueria (674/4. "Bot. Zeitung," 1866.)]; it is as wonderful as the most wonderful orchis; Ernst Hackel brought me the paper and stayed a day with me. I have seldom seen a more pleasant, cordial, and frank man. He is now in Madeira, where he is going to work chiefly on the Medusae. His great work is now published, and I have a copy; but the german is so difficult I can make out but little of it, and I fear it is too large a work to be translated. Your fact about the number of seeds in the capsule of the Maxillaria (674/5. See "Animals and Plants," Edition II., Volume II., page 115.) came just at the right time, as I wished to give one or two such facts. Does this orchid produce many capsules? I cannot answer your question about the aerial roots of Catasetum. I hope you have received the new edition of the "Origin." Your paper on climbing plants (674/6. "Linn. Soc. Journal," IX., 1867, page 344.) is printed, and I expect in a day or two to receive the spare copies, and I will send off three copies as before stated, and will retain some in case you should wish me to send them to any one in Europe, and will transmit the remainder to yourself. LETTER 675. TO F. MULLER. Down [received February 24th, 1867]. Your letter of November 2nd contained an extraordinary amount of interesting matter. What a number of dimorphic plants South Brazil produces: you observed in one day as many or more dimorphic genera than all the botanists in Europe have ever observed. When my present book is finished I shall write a final paper upon these plants, so that I am extremely glad to hear of your observations and to see the dried flowers; nevertheless, I should regret MUCH if I prevented you from publishing on the subject. Plumbago (675/1. Plumbago has not been shown to be dimorphic.) is quite new to me, though I had suspected it. It is curious how dimorphism prevails by groups throughout the world, showing, as I suppose, that it is an ancient character; thus Hedyotis is dimorphic in India (675/2. Hedyotis was sent to Darwin by F. Muller; it seems possible, therefore, that Hedyotis was written by mistake for some other Rubiaceous plant, perhaps Oldenlandia, which John Scott sent him from India.); the two other genera in the same sub-family with Villarsia are dimorphic in Europe and Ceylon; a sub-genus of Erythroxylon (675/3. No doubt Sethia.) is dimorphic in Ceylon, and Oxalis with you and at the Cape of Good Hope. If you can find a dimorphic Oxalis it will be a new point, for all known species are trimorphic or monomorphic. The case of Convolvulus will be new, if proved. I am doubtful about Gesneria (675/4. Neither Convolvulus nor Gesneria have been shown to be dimorphic.), and have been often myself deceived by varying length of pistil. A difference in the size of the pollen-grains would be conclusive evidence; but in some cases experiments by fertilisation can alone decide the point. As yet I know of no case of dimorphism in flowers which are very irregular; such flowers being apparently always sufficiently visited and crossed by insects. LETTER 676. TO F. MULLER. Down, April 22nd [1867]. I am very sorry your papers on climbing plants never reached you. They must be lost, but I put the stamps on myself and I am sure they were right. I despatched on the 20th all the remaining copies, except one for myself. Your letter of March 4th contained much interesting matter, but I have to say this of all your letters. I am particularly glad to hear that Oncidium flexuosum (676/1. See "Animals and Plants," Edition II., Volume II., page 114. Observations on Oncidium were made by John Scott, and in Brazil by F. Muller, who "fertilised above one hundred flowers of the above-mentioned Oncidium flexuosum, which is there endemic, with its own pollen, and with that taken from distinct plants: all the former were sterile, whilst those fertilised by pollen from any OTHER PLANT of the same species were fertile.') is endemic, for I always thought that the cases of self-sterility with orchids in hot-houses might have been caused by their unnatural conditions. I am glad, also, to hear of the other analogous cases, all of which I will give briefly in my book that is now printing. The lessened number of good seeds in the self-fertilising Epidendrums is to a certain extent a new case. You suggest the comparison of the growth of plants produced from self-fertilised and crossed seeds. I began this work last autumn, and the result, in some cases, has been very striking; but only, as far as I can yet judge, with exotic plants which do not get freely crossed by insects in this country. In some of these cases it is really a wonderful physiological fact to see the difference of growth in the plants produced from self-fertilised and crossed seeds, both produced by the same parent-plant; the pollen which has been used for the cross having been taken from a distinct plant that grew in the same flower-pot. Many thanks for the dimorphic Rubiaceous plant. Three of your Plumbagos have germinated, but not as yet any of the Lobelias. Have you ever thought of publishing a work which might contain miscellaneous observations on all branches of Natural History, with a short description of the country and of any excursions which you might take? I feel certain that you might make a very valuable and interesting book, for every one of your letters is so full of good observations. Such books, for instance Bates' "Travels on the Amazons," are very popular in England. I will give your obliging offer about Brazilian plants to Dr. Hooker, who was to have come here to-day, but has failed. He is an excellent good fellow, as well as naturalist. He has lately published a pamphlet, which I think you would like to read; and I will try and get a copy and send you. (676/2. Sir J.D. Hooker's lecture on Insular Floras, given before the British Association in August, 1866, is doubtless referred to. It appeared in the "Gardeners' Chronicle," and was published as a pamphlet in January, 1867. This fact helps to fix the date of the present letter.) LETTER 677. TO F. MULLER. (677/1. The following refers to the curious case of Eschscholtzia described in "Cross and Self-Fertilisation," pages 343-4. The offspring of English plants after growing for two generations in Brazil became self-sterile, while the offspring of Brazilian plants became partly self-fertile in England.) January 30th [1868]. ...The flowers of Eschscholtzia when crossed with pollen from a distinct plant produced 91 per cent. of capsules; when self-fertilised the flowers produced only 66 per cent. of capsules. An equal number of crossed and self-fertilised capsules contained seed by weight in the proportion of 100 to 71. Nevertheless, the self-fertilised flowers produced an abundance of seed. I enclose a few crossed seeds in hopes that you will raise a plant, cover it with a net, and observe whether it is self-fertile; at the same time allowing several uncovered plants to produce capsules, for the sterility formerly observed by you seems to me very curious. LETTER 678. TO F. MULLER. Down, November 28th [1868]. You end your letter of September 9th by saying that it is a very dull one; indeed, you make a very great mistake, for it abounds with interesting facts and thoughts. Your account of the tameness of the birds which apparently have wandered from the interior, is very curious. But I must begin on another subject: there has been a great and very vexatious, but unavoidable delay in the publication of your book. (678/1. "Facts and Arguments for Darwin," 1869, a translation by the late Mr. Dallas of F. Muller's "Fur Darwin," 1864: see Volume I., Letter 227.) Prof. Huxley agrees with me that Mr. Dallas is by far the best translator, but he is much overworked and had not quite finished the translation about a fortnight ago. He has charge of the Museum at York, and is now trying to get the situation of Assistant Secretary at the Geological Society; and all the canvassing, etc., and his removal, if he gets the place, will, I fear, cause more than a month's delay in the completion of the translation; and this I very much regret. I am particularly glad to hear that you intend to repeat my experiments on illegitimate offspring, for no one's observations can be trusted until repeated. You will find the work very troublesome, owing to the death of plants and accidents of all kinds. Some dimorphic plant will probably prove too sterile for you to raise offspring; and others too fertile for much sterility to be expected in their offspring. Primula is bad on account of the difficulty of deciding which seeds may be considered as good. I have earnestly wished that some one would repeat these experiments, but I feared that years would elapse before any one would take the trouble. I received your paper on Bignonia in "Bot. Zeit." and it interested me much. (678/2. See "Variation of Animals and Plants," Edition II., Volume II., page 117. Fritz Muller's paper, "Befruchtungsversuche an Cipo alho (Bignonia)," "Botanische Zeitung," September 25th, 1868, page 625, contains an interesting foreshadowing of the generalisation arrived at in "Cross and Self-Fertilisation." Muller wrote: "Are the three which grow near each other seedlings from the same mother-plant or perhaps from seeds of the same capsule? Or have they, from growing in the same place and under the same conditions, become so like each other that the pollen of one has hardly any more effect on the others than their own pollen? Or, on the contrary, were the plants originally one--i.e., are they suckers from a single stock, which have gained a slight degree of mutual fertility in the course of an independent life? Or, lastly, is the result 'ein neckische Zufall,'" (The above is a free translation of Muller's words.)) I am convinced that if you can prove that a plant growing in a distant place under different conditions is more effective in fertilisation than one growing close by, you will make a great step in the essence of sexual reproduction. Prof. Asa Gray and Dr. Hooker have been staying here, and, oddly enough, they knew nothing of your paper on Martha (678/3. F. Muller has described ("Bot. Zeitung," 1866, page 129) the explosive mechanism by which the pollen is distributed in Martha (Posoqueria) fragrans. He also gives an account of the remarkable arrangement for ensuring cross-fertilisation. See "Forms of Flowers," Edition II., page 131.), though the former was aware of the curious movements of the stamens, but so little understood the structure of the plant that he thought it was probably a dimorphic species. Accordingly, I showed them your drawings and gave them a little lecture, and they were perfectly charmed with your account. Hildebrand (678/4. See Letter 206, Volume I.) has repeated his experiments on potatoes, and so have I, but this summer with no result. LETTER 679. TO F. MULLER. Down, March 14th [1869]. I received some time ago a very interesting letter from you with many facts about Oxalis, and about the non-seeding and spreading of one species. I may mention that our common O. acetosella varies much in length of pistils and stamens, so that I at first thought it was certainly dimorphic, but proved it by experiment not to be so. Boiseria (679/1. This perhaps refers to Boissiera (Ladizabala).) has after all seeded well with me when crossed by opposite form, but very sparingly when self-fertilised. Your case of Faramea astonishes me. (679/2. See "Forms of Flowers," Edition II., page 129. Faramea is placed among the dimorphic species.) Are you sure there is no mistake? The difference in size of flower and wonderful difference in size and structure of pollen-grains naturally make me rather sceptical. I never fail to admire and to be surprised at the number of points to which you attend. I go on slowly at my next book, and though I never am idle, I make but slow progress; for I am often interrupted by being unwell, and my subject of sexual selection has grown into a very large one. I have also had to correct a new edition of my "Origin," (679/3. The 5th edition.), and this has taken me six weeks, for science progresses at railroad speed. I cannot tell you how rejoiced I am that your book is at last out; for whether it sells largely or not, I am certain it will produce a great effect on all capable judges, though these are few in number. P.S.--I have just received your letter of January 12th. I am greatly interested by what you say on Eschscholtzia; I wish your plants had succeeded better. It seems pretty clear that the species is much more self-sterile under the climate of Brazil than here, and this seems to me an important result. (679/4. See Letter 677.) I have no spare seeds at present, but will send for some from the nurseryman, which, though not so good for our purpose, will be worth trying. I can send some of my own in the autumn. You could simply cover up separately two or three single plants, and see if they will seed without aid,--mine did abundantly. Very many thanks for seeds of Oxalis: how I wish I had more strength and time to carry on these experiments, but when I write in the morning, I have hardly heart to do anything in the afternoon. Your grass is most wonderful. You ought to send account to the "Bot. Zeitung." Could you not ascertain whether the barbs are sensitive, and how soon they become spiral in the bud? Your bird is, I have no doubt, the Molothrus mentioned in my "Journal of Travels," page 52, as representing a North American species, both with cuckoo-like habits. I know that seeds from same spike transmitted to a certain extent their proper qualities; but as far as I know, no one has hitherto shown how far this holds good, and the fact is very interesting. The experiment would be well worth trying with flowers bearing different numbers of petals. Your explanation agrees beautifully with the hypothesis of pangenesis, and delights me. If you try other cases, do draw up a paper on the subject of inheritance of separate flowers for the "Bot. Zeitung" or some journal. Most men, as far as my experience goes, are too ready to publish, but you seem to enjoy making most interesting observations and discoveries, and are sadly too slow in publishing. LETTER 680. TO F. MULLER. Barmouth, July 18th, 1869. I received your last letter shortly before leaving home for this place. Owing to this cause and to having been more unwell than usual I have been very dilatory in writing to you. When I last heard, about six or eight weeks ago, from Mr. Murray, one hundred copies of your book had been sold, and I daresay five hundred may now be sold. (680/1. "Facts and Arguments for Darwin," 1869: see Volume I., Letter 227.) This will quite repay me, if not all the money; for I am sure that your book will have got into the hands of a good many men capable of understanding it: indeed, I know that it has. But it is too deep for the general public. I sent you two or three reviews--one of which, in the "Athenaeum," was unfavourable; but this journal has abused me, and all who think with me, for many years. (680/2. "Athenaeum," 1869, page 431.) I enclose two more notices, not that they are worth sending: some other brief notices have appeared. The case of the Abitulon sterile with some individuals is remarkable (680/3. "Bestaubungsversuche an Abutilon-Arten." "Jenaische Zeitschr." VII., 1873, page 22.): I believe that I had one plant of Reseda odorata which was fertile with own pollen, but all that I have tried since were sterile except with pollen from some other individual. I planted the seeds of the Abitulon, but I fear that they were crushed in the letter. Your Eschscholtzia plants were growing well when I left home, to which place we shall return by the end of this month, and I will observe whether they are self-sterile. I sent your curious account of the monstrous Begonia to the Linnean Society, and I suppose it will be published in the "Journal." (680/4. "On the Modification of the Stamens in a Species of Begonia." "Journ. Linn. Soc." XI., 1871, page 472.) I sent the extract about grafted orange trees to the "Gardeners' Chronicle," where it appeared. I have lately drawn up some notes for a French translation of my Orchis book: I took out your letters to make an abstract of your numerous discussions, but I found I had not strength or time to do so, and this caused me great regret. I have [in the French edition] alluded to your work, which will also be published in English, as you will see in my paper, and which I will send you. (680/5. "Notes on the Fertilisation of Orchids." "Ann. Mag. Nat. Hist." 1869, Volume IV., page 141. The paper gives an English version of the notes prepared for the French edition of the Orchid book.) P.S.--By an odd chance, since I wrote the beginning of this letter, I have received one from Dr. Hooker, who has been reading "Fur Darwin": he finds that he has not knowledge enough for the first part; but says that Chapters X. and XI. "strike me as remarkably good." He is also particularly struck with one of your highly suggestive remarks in the note to page 119. Assuredly all who read your book will greatly profit by it, and I rejoice that it has appeared in English. LETTER 681. TO F. MULLER. Down, December 1st [1869]. I am much obliged for your letter of October 18th, with the curious account of Abutilon, and for the seeds. A friend of mine, Mr. Farrer, has lately been studying the fertilisation of Passiflora (681/1. See Letters 701 and 704.), and concluded from the curiously crooked passage into the nectary that it could not be fertilised by humming-birds; but that Tacsonia was thus fertilised. Therefore I sent him the passage from your letter, and I enclose a copy of his answer. If you are inclined to gratify him by making a few observations on this subject I shall be much obliged, and will send them on to him. I enclose a copy of my rough notes on your Eschscholtzia, as you might like to see them. Somebody has sent me from Germany two papers by you, one with a most curious account of Alisma (681/2. See Letter 672.), and the other on crustaceans. Your observations on the branchiae and heart have interested me extremely. Alex. Agassiz has just paid me a visit with his wife. He has been in England two or three months, and is now going to tour over the Continent to see all the zoologists. We liked him very much. He is a great admirer of yours, and he tells me that your correspondence and book first made him believe in evolution. This must have been a great blow to his father, who, as he tells me, is very well, and so vigorous that he can work twice as long as he (the son) can. Dr. Meyer has sent me his translation of Wallace's "Malay Archipelago," which is a valuable work; and as I have no use for the translation, I will this day forward it to you by post, but, to save postage, via England. LETTER 682. TO F. MULLER. Down, May 12th [1870]. I thank you for your two letters of December 15th and March 29th, both abounding with curious facts. I have been particularly glad to hear in your last about the Eschscholtzia (682/1. See Letter 677.); for I am now rearing crossed and self-fertilised plants, in antagonism to each other, from your semi-sterile plants so that I may compare this comparative growth with that of the offspring of English fertile plants. I have forwarded your postscript about Passiflora, with the seeds, to Mr. Farrer, who I am sure will be greatly obliged to you; the turning up of the pendant flower plainly indicates some adaptation. When I next go to London I will take up the specimens of butterflies, and show them to Mr. Butler, of the British Museum, who is a learned lepidopterist and interested on the subject. This reminds me to ask you whether you received my letter [asking] about the ticking butterfly, described at page 33 of my "Journal of Researches"; viz., whether the sound is in anyway sexual? Perhaps the species does not inhabit your island. (682/2. Papilio feronia, a Brazilian species capable of making "a clicking noise, similar to that produced by a toothed wheel passing under a spring catch."--"Journal," 1879, page 34.) The case described in your last letter of the trimorphic monocotyledon Pontederia is grand. (682/3. This case interested Darwin as the only instance of heterostylism in Monocotyledons. See "Forms of Flowers," Edition II., page 183. F. Muller's paper is in the "Jenaische Zeitschrift," 1871.) I wonder whether I shall ever have time to recur to this subject; I hope I may, for I have a good deal of unpublished material. Thank you for telling me about the first-formed flower having additional petals, stamens, carpels, etc., for it is a possible means of transition of form; it seems also connected with the fact on which I have insisted of peloric flowers being so often terminal. As pelorism is strongly inherited (and [I] have just got a curious case of this in a leguminous plant from India), would it not be worth while to fertilise some of your early flowers having additional organs with pollen from a similar flower, and see whether you could not make a race thus characterised? (682/4. See Letters 588, 589. Also "Variation under Domestication," Edition II., Volume I., pages 388-9.) Some of your Abutilons have germinated, but I have been very unfortunate with most of your seed. You will remember having given me in a former letter an account of a very curious popular belief in regard to the subsequent progeny of asses, which have borne mules; and now I have another case almost exactly like that of Lord Morton's mare, in which it is said the shape of the hoofs in the subsequent progeny are affected. (Pangenesis will turn out true some day!) (682/5. See "Animals and Plants," Edition II., Volume I., page 435. For recent work on telegony see Ewart's "Experimental Investigations on Telegony," "Phil. Trans. R. Soc." 1899. A good account of the subject is given in the "Quarterly Review," 1899, page 404. See also Letter 275, Volume I.) A few months ago I received an interesting letter and paper from your brother, who has taken up a new and good line of investigation, viz., the adaptation in insects for the fertilisation of flowers. The only scientific man I have seen for several months is Kolliker, who came here with Gunther, and whom I liked extremely. I am working away very hard at my book on man and on sexual selection, but I do not suppose I shall go to press till late in the autumn. LETTER 683. TO F. MULLER. Down, January 1st, 1874. No doubt I owe to your kindness two pamphlets received a few days ago, which have interested me in an extraordinary degree. (683/1. This refers to F. Muller's "Bestaubungsversuche an Abutilon-Arten" in the "Jenaische Zeitschr." Volume VII., which are thus referred to by Darwin ("Cross and Self Fert." pages 305-6): "Fritz Muller has shown by his valuable experiments on hybrid Abutilons, that the union of brothers and sisters, parents and children, and of other near relations is highly injurious to the fertility of the offspring." The Termite paper is in the same volume (viz., VII.) of the "Jenaische Zeitschr.") It is quite new to me what you show about the effects of relationship in hybrids--that is to say, as far as direct proof is concerned. I felt hardly any doubt on the subject, from the fact of hybrids becoming more fertile when grown in number in nursery gardens, exactly the reverse of what occurred with Gartner. (683/2. When many hybrids are grown together the pollination by near relatives is minimised.) The paper on Termites is even still more interesting, and the analogy with cleistogene flowers is wonderful. (683/3. On the back of his copy of Muller's paper Darwin wrote: "There exist imperfectly developed male and female Termites, with wings much shorter than those of queen and king, which serve to continue the species if a fully developed king and queen do not after swarming (which no doubt is for an occasional cross) enter [the] nest. Curiously like cleistogamic flowers.") The manner in which you refer to to my chapter on crossing is one of the most elegant compliments which I have ever received. I have directed to be sent to you Belt's "Nicaragua," which seems to me the best Natural History book of travels ever published. Pray look to what he says about the leaf-carrying ant storing the leaves up in a minced state to generate mycelium, on which he supposes that the larvae feed. Now, could you open the stomachs of these ants and examine the contents, so as to prove or disprove this remarkable hypothesis? (683/4. The hypothesis has been completely confirmed by the researches of Moller, a nephew of F. Muller's: see his "Brasilische Pilzblumen" ("Botan. Mittheilgn. aus den Tropen," hrsg. von A.F.W. Schimper, Heft 7).) LETTER 684. TO F. MULLER. Down, May 9th, 1877. I have been particularly glad to receive your letter of March 25th on Pontederia, for I am now printing a small book on heterostyled plants, and on some allied subjects. I feel sure you will not object to my giving a short account of the flowers of the new species which you have sent me. I am the more anxious to do so as a writer in the United States has described a species, and seems to doubt whether it is heterostyled, for he thinks the difference in the length of the pistil depends merely on its growth! In my new book I shall use all the information and specimens which you have sent me with respect to the heterostyled plants, and your published notices. One chapter will be devoted to cleistogamic species, and I will just notice your new grass case. My son Francis desires me to thank you much for your kindness with respect to the plants which bury their seeds. I never fail to feel astonished, when I receive one of your letters, at the number of new facts you are continually observing. With respect to the great supposed subterranean animal, may not the belief have arisen from the natives having seen large skeletons embedded in cliffs? I remember finding on the banks of the Parana a skeleton of a Mastodon, and the Gauchos concluded that it was a borrowing animal like the Bizcacha. (684/1. On the supposed existence in Patagonia of a gigantic land-sloth, see "Natural Science," XIII., 1898, page 288, where Ameghino's discovery of the skin of Neomylodon listai was practically first made known, since his privately published pamphlet was not generally seen. The animal was afterwards identified with a Glossotherium, closely allied to Owen's G. Darwini, which has been named Glossotherium listai or Grypotherium domesticum. For a good account of the discoveries see Smith Woodward in "Natural Science," XV., 1899, page 351, where the literature is given.) LETTER 685. TO F. MULLER. Down, May 14th [1877]. I wrote to you a few days ago to thank you about Pontederia, and now I am going to ask you to add one more to the many kindnesses which you have done for me. I have made many observations on the waxy secretion on leaves which throw off water (e.g., cabbage, Tropoeolum), and I am now going to continue my observations. Does any sensitive species of Mimosa grow in your neighbourhood? If so, will you observe whether the leaflets keep shut during long-continued warm rain. I find that the leaflets open if they are continuously syringed with water at a temperature of about 19 deg C., but if the water is at a temperature of 33-35 deg C., they keep shut for more than two hours, and probably longer. If the plant is continuously shaken so as to imitate wind the leaflets soon open. How is this with the native plants during a windy day? I find that some other plants--for instance, Desmodium and Cassia--when syringed with water, place their leaves so that the drops fall quickly off; the position assumed differing somewhat from that in the so-called sleep. Would you be so kind as to observe whether any [other] plants place their leaves during rain so as to shoot off the water; and if there are any such I should be very glad of a leaf or two to ascertain whether they are coated with a waxy secretion. (685/1. See Letters 737-41.) There is another and very different subject, about which I intend to write, and should be very glad of a little information. Are earthworms (Lumbricus) common in S. Brazil (685/2. F. Muller's reply is given in "Vegetable Mould," page 122.), and do they throw up on the surface of the ground numerous castings or vermicular masses such as we so commonly see in Europe? Are such castings found in the forests beneath the dead withered leaves? I am sure I can trust to your kindness to forgive me for asking you so many questions. LETTER 686. TO F. MULLER. Down, July 24th, 1878. Many thanks for the five kinds of seeds; all have germinated, and the Cassia seedlings have interested me much, and I daresay that I shall find something curious in the other plants. Nor have I alone profited, for Sir J. Hooker, who was here on Sunday, was very glad of some of the seeds for Kew. I am particularly obliged for the information about the earthworms. I suppose the soil in your forests is very loose, for in ground which has lately been dug in England the worms do not come to the surface, but deposit their castings in the midst of the loose soil. I have some grand plants (and I formerly sent seeds to Kew) of the cleistogamic grass, but they show no signs of producing flowers of any kind as yet. Your case of the panicle with open flowers being sterile is parallel to that of Leersia oryzoides. I have always fancied that cross-fertilisation would perhaps make such panicles fertile. (686/1. The meaning of this sentence is somewhat obscure. Darwin apparently implies that the perfect flowers, borne on the panicles which occasionally emerge from the sheath, might be fertile if pollinated from another individual. See "Forms of Flowers," page 334.) I am working away as hard as I can at all the multifarious kinds of movements of plants, and am trying to reduce them to some simple rules, but whether I shall succeed I do not know. I have sent the curious lepidopteron case to Mr. Meldola. LETTER 687. F. MULLER TO CHARLES DARWIN. (687/1. In November, 1880, on receipt of an account of a flood in Brazil from which Fritz Muller had barely escaped with his life ("Life and Letters," III., 242); Darwin immediately wrote to Hermann Muller begging to be allowed to help in making good any loss in books or scientific instruments that his brother had sustained. It is this offer of help that is referred to in the first paragraph of the following letter: Darwin repeats the offer in Letter 690.) Blumenau, Sa Catharina, Brazil, January 9th, 1881. I do not know how to express [to] you my deep heartfelt gratitude for the generous offer which you made to my brother on hearing of the late dreadful flood of the Itajahy. From you, dear sir, I should have accepted assistance without hesitation if I had been in need of it; but fortunately, though we had to leave our house for more than a week, and on returning found it badly damaged, my losses have not been very great. I must thank you also for your wonderful book on the movements of plants, which arrived here on New Year's Day. I think nobody else will have been delighted more than I was with the results which you have arrived at by so many admirably conducted experiments and observations; since I observed the spontaneous revolving movement of Alisma I had seen similar movements in so many and so different plants that I felt much inclined to consider spontaneous revolving movement or circumnutation as common to all plants and the movements of climbing plants as a special modification of that general phenomenon. And this you have now convincingly, nay, superabundantly, proved to be the case. I was much struck with the fact that with you Maranta did not sleep for two nights after having its leaves violently shaken by wind, for here we have very cold nights only after storms from the west or south-west, and it would be very strange if the leaves of our numerous species of Marantaceae should be prevented by these storms to assume their usual nocturnal position, just when nocturnal radiation was most to be feared. It is rather strange, also, that Phaseolus vulgaris should not sleep during the early part of the summer, when the leaves are most likely to be injured during cold nights. On the contrary, it would not do any harm to many sub-tropical plants, that their leaves must be well illuminated during the day in order that they may assume at night a vertical position; for, in our climate at least, cold nights are always preceded by sunny days. Of nearly allied plants sleeping very differently I can give you some more instances. In the genus Olyra (at least, in the one species observed by me) the leaves bend down vertically at night; now, in Endlicher's "Genera plantarum" this genus immediately precedes Strephium, the leaves of which you saw rising vertically. In one of two species of Phyllanthus, growing as weeds near my house, the leaves of the erect branches bend upwards at night, while in the second species, with horizontal branches, they sleep like those of Phyllanthus Niruri or of Cassia. In this second species the tips of the branches also are curled downwards at night, by which movement the youngest leaves are yet better protected. From their vertical nyctitropic position the leaves of this Phyllanthus might return to horizontality, traversing 90 deg, in two ways, either to their own or to the opposite side of the branch; on the latter way no rotation would be required, while on the former each leaf must rotate on its own axis in order that its upper surface may be turned upwards. Thus the way to the wrong side appears to be even less troublesome. And indeed, in some rare cases I have seen three, four or even almost all the leaves of one side of a branch horizontally expanded on the opposite side, with their upper surfaces closely appressed to the lower surfaces of the leaves of that side. This Phyllanthus agrees with Cassia not only in its manner of sleeping, but also by its leaves being paraheliotropic. (687/2. Paraheliotropism is the movement by which some leaves temporarily direct their edges to the source of light. See "Movements of Plants," page 445.) Like those of some Cassiae its leaves take an almost perfectly vertical position, when at noon, on a summer day, the sun is nearly in the zenith; but I doubt whether this paraheliotropism will be observable in England. To-day, though continuing to be fully exposed to the sun, at 3 p.m. the leaves had already returned to a nearly horizontal position. As soon as there are ripe seeds I will send you some; of our other species of Phyllanthus I enclose a few seeds in this letter. In several species of Hedychium the lateral halves of the leaves when exposed to bright sunshine, bend downwards so that the lateral margins meet. It is curious that a hybrid Hedychium in my garden shows scarcely any trace of this paraheliotropism, while both the parent species are very paraheliotropic. Might not the inequality of the cotyledons of Citrus and of Pachira be attributed to the pressure, which the several embryos enclosed in the same seed exert upon each other? I do not know Pachira aquatica, but [in] a species, of which I have a tree in my garden, all the seeds are polyembryonic, and so were almost all the seeds of Citrus which I examined. With Coffea arabica also seeds including two embryos are not very rare; but I have not yet observed whether in this case the cotyledons be inequal. I repeated to-day Duval-Jouve's measurements on Bryophyllum calycinum (687/3. "Power of Movement in Plants," page 237. F. Muller's measurements show, however, that there is a tendency in the leaves to be more highly inclined at night than in the middle of the day, and so far they agree with Duval-Jouve's results.); but mine did not agree with his; they are as follows:-- Distances in mm. between the tips of the upper pair of leaves. January 9th, 1881 3 A.M. 1 P.M. 6 P.M. 1st plant 54 43 36 2nd plant 28 25 23 3rd plant 28 27 27 4th plant 51 46 39 5th plant 61 52 45 _______________________________________________ 222 193 170 LETTER 688. TO F. MULLER. Down, February 23rd, 1881. Your letter has interested me greatly, as have so many during many past years. I thought that you would not object to my publishing in "Nature" (688/1. "Nature," March 3rd, 1881, page 409.) some of the more striking facts about the movements of plants, with a few remarks added to show the bearing of the facts. The case of the Phyllanthus (688/2. See Letter 687.), which turns up its leaves on the wrong side, is most extraordinary and ought to be further investigated. Do the leaflets sleep on the following night in the usual manner? Do the same leaflets on successive nights move in the same strange manner? I was particularly glad to hear of the strongly marked cases of paraheliotropism. I shall look out with much interest for the publication about the figs. (688/3. F. Muller published on Caprification in "Kosmos," 1882.) The creatures which you sketch are marvellous, and I should not have guessed that they were hymenoptera. Thirty or forty years ago I read all that I could find about caprification, and was utterly puzzled. I suggested to Dr. Cruger in Trinidad to investigate the wild figs, in relation to their cross-fertilisation, and just before he died he wrote that he had arrived at some very curious results, but he never published, as I believe, on the subject. I am extremely glad that the inundation did not so greatly injure your scientific property, though it would have been a real pleasure to me to have been allowed to have replaced your scientific apparatus. (688/4. See Letter 687.) I do not believe that there is any one in the world who admires your zeal in science and wonderful powers of observation more than I do. I venture to say this, as I feel myself a very old man, who probably will not last much longer. P.S.--With respect to Phyllanthus, I think that it would be a good experiment to cut off most of the leaflets on one side of the petiole, as soon as they are asleep and vertically dependent; when the pressure is thus removed, the opposite leaflets will perhaps bend beyond their vertically dependent position; if not, the main petiole might be a little twisted so that the upper surfaces of the dependent and now unprotected leaflets should face obliquely the sky when the morning comes. In this case diaheliotropism would perhaps conquer the ordinary movements of the leaves when they awake, and [assume] their diurnal horizontal position. As the leaflets are alternate, and as the upper surface will be somewhat exposed to the dawning light, it is perhaps diaheliotropism which explains your extraordinary case. LETTER 689. TO F. MULLER. Down, April 12th, 1881. I have delayed answering your last letter of February 25th, as I was just sending to the printers the MS. of a very little book on the habits of earthworms, of which I will of course send you a copy when published. I have been very much interested by your new facts on paraheliotropism, as I think that they justify my giving a name to this kind of movement, about which I long doubted. I have this morning drawn up an account of your observations, which I will send in a few days to "Nature." (689/1. "Nature," 1881, page 603. Curious facts are given on the movements of Cassia, Phyllanthus, sp., Desmodium sp. Cassia takes up a sunlight position unlike its own characteristic night-position, but resembling rather that of Haematoxylon (see "Power of Movement," figure 153, page 369). One species of Phyllanthus takes up in sunshine the nyctitropic attitude of another species. And the same sort of relation occurs in the genus Bauhinia.) I have thought that you would not object to my giving precedence to paraheliotropism, which has been so little noticed. I will send you a copy of "Nature" when published. I am glad that I was not in too great a hurry in publishing about Lagerstroemia. (689/2. Lagerstraemia was doubtfully placed among the heterostyled plants ("Forms of Flowers," page 167). F. Muller's observations showed that a totally different interpretation of the two sizes of stamen is possible. Namely, that one set serves merely to attract pollen-collecting bees, who in the act of visiting the flowers transfer the pollen of the longer stamens to other flowers. A case of this sort in Heeria, a Melastomad, was described by Muller ("Nature," August 4th, 1881, page 308), and the view was applied to the cases of Lagerstroemia and Heteranthera at a later date ("Nature," 1883, page 364). See Letters 620-30.) I have procured some plants of Melastomaceae, but I fear that they will not flower for two years, and I may be in my grave before I can repeat my trials. As far as I can imperfectly judge from my observations, the difference in colour of the anthers in this family depends on one set of anthers being partially aborted. I wrote to Kew to get plants with differently coloured anthers, but I learnt very little, as describers of dried plants do not attend to such points. I have, however, sowed seeds of two kinds, suggested to me as probable. I have, therefore, been extremely glad to receive the seeds of Heteranthera reniformis. As far as I can make out it is an aquatic plant; and whether I shall succeed in getting it to flower is doubtful. Will you be so kind as to send me a postcard telling me in what kind of station it grows. In the course of next autumn or winter, I think that I shall put together my notes (if they seem worth publishing) on the use or meaning of "bloom" (689/3. See Letters 736-40.), or the waxy secretion which makes some leaves glaucous. I think that I told you that my experiments had led me to suspect that the movement of the leaves of Mimosa, Desmodium and Cassia, when shaken and syringed, was to shoot off the drops of water. If you are caught in heavy rain, I should be very much obliged if you would keep this notion in your mind, and look to the position of such leaves. You have such wonderful powers of observation that your opinion would be more valued by me than that of any other man. I have among my notes one letter from you on the subject, but I forget its purport. I hope, also, that you may be led to follow up your very ingenious and novel view on the two-coloured anthers or pollen, and observe which kind is most gathered by bees. LETTER 690. TO F. MULLER. [Patterdale], June 21st, 1881. I should be much obliged if you could without much trouble send me seeds of any heterostyled herbaceous plants (i.e. a species which would flower soon), as it would be easy work for me to raise some illegitimate seedlings to test their degree of infertility. The plant ought not to have very small flowers. I hope that you received the copies of "Nature," with extracts from your interesting letters (690/1. "Nature," March 3rd, 1881, Volume XXIII., page 409, contains a letter from C. Darwin on "Movements of Plants," with extracts from Fritz Muller's letter. Another letter, "On the Movements of Leaves," was published in "Nature," April 28th, 1881, page 603, with notes on leaf-movements sent to Darwin by Muller.), and I was glad to see a notice in "Kosmos" on Phyllanthus. (690/2. "Verirrte Blatter," by Fritz Muller ("Kosmos," Volume V., page 141, 1881). In this article an account is given of a species of Phyllanthus, a weed in Muller's garden. See Letter 687.) I am writing this note away from my home, but before I left I had the satisfaction of seeing Phyllanthus sleeping. Some of the seeds which you so kindly sent me would not germinate, or had not then germinated. I received a letter yesterday from Dr. Breitenbach, and he tells me that you lost many of your books in the desolating flood from which you suffered. Forgive me, but why should you not order, through your brother Hermann, books, etc., to the amount of 100 pounds, and I would send a cheque to him as soon as I heard the exact amount? This would be no inconvenience to me; on the contrary, it would be an honour and lasting pleasure to me to have aided you in your invaluable scientific work to this small and trifling extent. (690/3. See Letter 687, also "Life and Letters," III., page 242.) LETTER 691. TO F. MULLER. (691/1. The following extract from a letter to F. Muller shows what was the nature of Darwin's interest in the effect of carbonate of ammonia on roots, etc. He was, we think, wrong in adhering to the belief that the movements of aggregated masses are of an amoeboid nature. The masses change shape, just as clouds do under the moulding action of the wind. In the plant cell the moulding agent is the flowing protoplasm, but the masses themselves are passive.) September 10th, 1881. Perhaps you may remember that I described in "Insectivorous Plants" a really curious phenomenon, which I called the aggregation of the protoplasm in the cells of the tentacles. None of the great German botanists will admit that the moving masses are composed of protoplasm, though it is astonishing to me that any one could watch the movement and doubt its nature. But these doubts have led me to observe analogous facts, and I hope to succeed in proving my case. LETTER 692. TO F. MULLER. Down, November 13th, 1881. I received a few days ago a small box (registered) containing dried flower-heads with brown seeds somewhat sculptured on the sides. There was no name, and I should be much obliged if some time you would tell me what these seeds are. I have planted them. I sent you some time ago my little book on earthworms, which, though of no importance, has been largely read in England. I have little or nothing to tell you about myself. I have for a couple of months been observing the effects of carbonate of ammonia on chlorophyll and on the roots of certain plants (692/1. Published under the title "The Action of Carbonate of Ammonia on the Roots of Certain Plants and on Chlorophyll Bodies," "Linn. Soc. Journ." XIX., 1882, pages 239-61, 262-84.), but the subject is too difficult for me, and I cannot understand the meaning of some strange facts which I have observed. The mere recording new facts is but dull work. Professor Wiesner has published a book (692/2. See Letter 763.), giving a different explanation to almost every fact which I have given in my "Power of Movement in Plants." I am glad to say that he admits that almost all my statements are true. I am convinced that many of his interpretations of the facts are wrong, and I am glad to hear that Professor Pfeffer is of the same opinion; but I believe that he is right and I wrong on some points. I have not the courage to retry all my experiments, but I hope to get my son Francis to try some fresh ones to test Wiesner's explanations. But I do not know why I have troubled you with all this. LETTER 693. TO F. MULLER. [4, Bryanston Street], December 19th, 1881. I hope that you may find time to go on with your experiments on such plants as Lagerstroemia, mentioned in your letter of October 29th, for I believe you will arrive at new and curious results, more especially if you can raise two sets of seedlings from the two kinds of pollen. Many thanks for the facts about the effect of rain and mud in relation to the waxy secretion. I have observed many instances of the lower side being protected better than the upper side, in the case, as I believe, of bushes and trees, so that the advantage in low-growing plants is probably only an incidental one. (693/1. The meaning is here obscure: it appears to us that the significance of bloom on the lower surface of the leaves of both trees and herbs depends on the frequency with which all or a majority of the stomata are on the lower surface--where they are better protected from wet (even without the help of bloom) than on the exposed upper surface. On the correlation between bloom and stomata, see Francis Darwin "Linn. Soc. Journ." XXII., page 99.) As I am writing away from my home, I have been unwilling to try more than one leaf of the Passiflora, and this came out of the water quite dry on the lower surface and quite wet on the upper. I have not yet begun to put my notes together on this subject, and do not at all know whether I shall be able to make much of it. The oddest little fact which I have observed is that with Trifolium resupinatum, one half of the leaf (I think the right-hand side, when the leaf is viewed from the apex) is protected by waxy secretion, and not the other half (693/2. In the above passage "leaf" should be "leaflet": for a figure of Trifolium resupinatum see Letter 740.); so that when the leaf is dipped into water, exactly half the leaf comes out dry and half wet. What the meaning of this can be I cannot even conjecture. I read last night your very interesting article in "Kosmos" on Crotalaria, and so was very glad to see the dried leaves sent by you: it seems to me a very curious case. I rather doubt whether it will apply to Lupinus, for, unless my memory deceives me, all the leaves of the same plant sometimes behaved in the same manner; but I will try and get some of the same seeds of the Lupinus, and sow them in the spring. Old age, however, is telling on me, and it troubles me to have more than one subject at a time on hand. (693/3. In a letter to F. Muller (September 10, 1881) occurs a sentence which may appropriately close this series: "I often feel rather ashamed of myself for asking for so many things from you, and for taking up so much of your valuable time, but I can assure you that I feel grateful.") 2.XI.III. MISCELLANEOUS, 1868-1881. LETTER 694. TO G. BENTHAM. Down, April 22nd, 1868. I have been extremely much pleased by your letter, and I take it as a very great compliment that you should have written to me at such length...I am not at all surprised that you cannot digest pangenesis: it is enough to give any one an indigestion; but to my mind the idea has been an immense relief, as I could not endure to keep so many large classes of facts all floating loose in my mind without some thread of connection to tie them together in a tangible method. With respect to the men who have recently written on the crossing of plants, I can at present remember only Hildebrand, Fritz Muller, Delpino, and G. Henslow; but I think there are others. I feel sure that Hildebrand is a very good observer, for I have read all his papers, and during the last twenty years I have made unpublished observations on many of the plants which he describes. [Most of the criticisms which I sometimes meet with in French works against the frequency of crossing I am certain are the result of mere ignorance. I have never hitherto found the rule to fail that when an author describes the structure of a flower as specially adapted for self-fertilisation, it is really adapted for crossing. The Fumariaceae offer a good instance of this, and Treviranus threw this order in my teeth; but in Corydalis Hildebrand shows how utterly false the idea of self-fertilisation is. This author's paper on Salvia (694/1. Hildebrand, "Pringsheim's Jahrbucher," IV.) is really worth reading, and I have observed some species, and know that he is accurate]. (694/2. The passage within [] was published in the "Life and Letters," III., page 279.) Judging from a long review in the "Bot. Zeitung", and from what I know of some the plants, I believe Delpino's article especially on the Apocynaea, is excellent; but I cannot read Italian. (694/3. Hildebrand's paper in the "Bot. Zeitung," 1867, refers to Delpino's work on the Asclepiads, Apocyneae and other Orders.) Perhaps you would like just to glance at such pamphlets as I can lay my hands on, and therefore I will send them, as if you do not care to see them you can return them at once; and this will cause you less trouble than writing to say you do not care to see them. With respect to Primula, and one point about which I feel positive is that the Bardfield and common oxlips are fundamentally distinct plants, and that the common oxlip is a sterile hybrid. (694/4. For a general account of the Bardfield oxlip (Primula elatior) see Miller Christy, "Linn. Soc. Journ." Volume XXXIII., page 172, 1897.) I have never heard of the common oxlip being found in great abundance anywhere, and some amount of difference in number might depend on so small a circumstance as the presence of some moth which habitually sucked the primrose and cowslip. To return to the subject of crossing: I am experimenting on a very large scale on the difference in power and growth between plants raised from self-fertilised and crossed seeds, and it is no exaggeration to say that the difference in growth and vigour is sometimes truly wonderful. Lyell, Huxley, and Hooker have seen some of my plants, and been astonished; and I should much like to show them to you. I always supposed until lately that no evil effects would be visible until after several generations of self-fertilisation, but now I see that one generation sometimes suffices, and the existence of dimorphic plants and all the wonderful contrivances of orchids are quite intelligible to me. LETTER 695. TO T.H. FARRER (Lord Farrer). Down, June 5th, 1868. I must write a line to cry peccavi. I have seen the action in Ophrys exactly as you describe, and am thoroughly ashamed of my inaccuracy. (695/1. See "Fertilisation of Orchids," Edition II., page 46, where Lord Farrer's observations on the movement of the pollinia in Ophrys muscifera are given.) I find that the pollinia do not move if kept in a very damp atmosphere under a glass; so that it is just possible, though very improbable, that I may have observed them during a very damp day. I am not much surprised that I overlooked the movement in Habenaria, as it takes so long. (695/2. This refers to Peristylus viridis, sometimes known as Habenaria viridis. Lord Farrer's observations are given in "Fertilisation of Orchids," Edition II., page 63.) I am glad you have seen Listera; it requires to be seen to believe in the co-ordination in the position of the parts, the irritability, and the chemical nature of the viscid fluid. This reminds me that I carefully described to Huxley the shooting out of the pollinia in Catasetum, and received for an answer, "Do you really think that I can believe all that!" (695/3. See Letter 665.) LETTER 696. TO J.D. HOOKER. Down, December 2nd, 1868. It is a splendid scheme, and if you make only a beginning on a "Flora," which shall serve as an index to all papers on curious points in the life-history of plants, you will do an inestimable good service. Quite recently I was asked by a man how he could find out what was known on various biological points in our plants, and I answered that I knew of no such book, and that he might ask half a dozen botanists before one would chance to remember what had been published on this or that point. Not long ago another man, who had been experimenting on the quasi-bulbs on the leaves of Cardamine, wrote to me to complain that he could not find out what was known on the subject. It is almost certain that some early or even advanced students, if they found in their "Flora" a line or two on various curious points, with references for further investigation, would be led to make further observations. For instance, a reference to the viscid threads emitted by the seeds of Compositae, to the apparatus (if it has been described) by which Oxalis spurts out its seeds, to the sensitiveness of the young leaves of Oxalis acetosella with reference to O. sensitiva. Under Lathyrus nissolia it would [be] better to refer to my hypothetical explanation of the grass-like leaves than to nothing. (696/1. No doubt the view given in "Climbing Plants," page 201, that L. nissolia has been evolved from a form like L. aphaca.) Under a twining plant you might say that the upper part of the shoot steadily revolves with or against the sun, and so, when it strikes against any object it turns to the right or left, as the case may be. If, again, references were given to the parasitism of Euphrasia, etc., how likely it would be that some young man would go on with the investigation; and so with endless other facts. I am quite enthusiastic about your idea; it is a grand idea to make a "Flora" a guide for knowledge already acquired and to be acquired. I have amused myself by speculating what an enormous number of subjects ought to be introduced into a Eutopian (696/2. A mis-spelling of Utopian.) Flora, on the quickness of the germination of the seeds, on their means of dispersal; on the fertilisation of the flower, and on a score of other points, about almost all of which we are profoundly ignorant. I am glad to read what you say about Bentham, for my inner consciousness tells me that he has run too many forms together. Should you care to see an elaborate German pamphlet by Hermann Muller on the gradation and distinction of the forms of Epipactis and of Platanthera? (696/3. "Verhand. d. Nat. Ver. f. Pr. Rh. u. Wesfal." Jahrg. XXV.: see "Fertilisation of Orchids," Edition II., pages 74, 102.) It may be absurd in me to suggest, but I think you would find curious facts and references in Lecoq's enormous book (696/4. "Geographie Botanique," 9 volumes, 1854-58.), in Vaucher's four volumes (696/5. "Plantes d'Europe," 4 volumes, 1841.), in Hildebrand's "Geschlechter Vertheilung" (696/6 "Geschlechter Vertheilung bei den Pflanzen," 1 volume, Leipzig, 1867.), and perhaps in Fournier's "De la Fecondation." (696/7. "De la Fecondation dans les Phanerogames," par Eugene Fournier: thesis published in Paris in 1863. The facts noted in Darwin's copy are the explosive stamens of Parietaria, the submerged flowers of Alisma containing air, the manner of fertilisation of Lopezia, etc.) I wish you all success in your gigantic undertaking; but what a pity you did not think of it ten years ago, so as to have accumulated references on all sorts of subjects. Depend upon it, you will have started a new era in the floras of various countries. I can well believe that Mrs. Hooker will be of the greatest possible use to you in lightening your labours and arranging your materials. LETTER 697. TO J.D. HOOKER. Down, December 5th, 1868. ...Now I want to beg for assistance for the new edition of "Origin." Nageli himself urges that plants offer many morphological differences, which from being of no service cannot have been selected, and which he accounts for by an innate principle of progressive development. (697/1. Nageli's "Enstehung und Begriff der Naturhistorischen Art." An address delivered at the public session of the Royal Academy of Sciences of Munich, March 28th, 1865; published by the Academy. Darwin's copy is the 2nd edition; it bears signs, in the pencilled notes on the margins, of having been read with interest. Much of it was translated for him by a German lady, whose version lies with the original among his pamphlets. At page 27 Nageli writes: "It is remarkable that the useful adaptations which Darwin brings forward in the case of animals, and which may be discovered in numbers among plants, are exclusively of a physiological kind, that they always show the formation or transformation of an organ to a special function. I do not know among plants a morphological modification which can be explained on utilitarian principles." Opposite this passage Darwin has written "a very good objection": but Nageli's sentence seems to us to be of the nature of a truism, for it is clear that any structure whose evolution can be believed to have come about by Natural Selection must have a function, and the case falls into the physiological category. The various meanings given to the term morphological makes another difficulty. Nageli cannot use it in the sense of "structural"--in which sense it is often applied, since that would mean that no plant structures have a utilitarian origin. The essence of morphology (in the better and more precise sense) is descent; thus we say that a pollen-grain is morphologically a microspore. And this very example serves to show the falseness of Nageli's view, since a pollen-grain is an adaptation to aerial as opposed to aquatic fertilisation. In the 5th edition of the "Origin," 1869, page 151, Darwin discusses Nageli's essay, confining himself to the simpler statement that there are many structural characters in plants to which we cannot assign uses. See Volume I., Letter 207.) I find old notes about this difficulty; but I have hitherto slurred it over. Nageli gives as instances the alternate and spiral arrangement of leaves, and the arrangement of the cells in the tissues. Would you not consider as a morphological difference the trimerous, tetramerous, etc., divisions of flowers, the ovules being erect or suspended, their attachment being parietal or placental, and even the shape of the seed when of no service to the plant. Now, I have thought, and want to show, that such differences follow in some unexplained manner from the growth or development of plants which have passed through a long series of adaptive changes. Anyhow, I want to show that these differences do not support the idea of progressive development. Cassini states that the ovaria on the circumference and centre of Compos. flowers differ in essential characters, and so do the seeds in sculpture. The seeds of Umbelliferae in the same relative positions are coelospermous and orthospermous. There is a case given by Augt. St. Hilaire of an erect and suspended ovule in the same ovarium, but perhaps this hardly bears on the point. The summit flower, in Adoxa and rue differ from the lower flowers. What is the difference in flowers of the rue? how is the ovarium, especially in the rue? As Augt. St. Hilaire insists on the locularity of the ovarium varying on the same plant in some of the Rutaceae, such differences do not speak, as it seems to me, in favour of progressive development. Will you turn the subject in your mind, and tell me any more facts. Difference in structure in flowers in different parts of the same plant seems best to show that they are the result of growth or position or amount of nutriment. I have got your photograph (697/2. A photograph by Mrs. Cameron.) over my chimneypiece, and like it much; but you look down so sharp on me that I shall never be bold enough to wriggle myself out of any contradiction. Owen pitches into me and Lyell in grand style in the last chapter of volume 3 of "Anat. of Vertebrates." He is a cool hand. He puts words from me in inverted commas and alters them. (697/3. The passage referred to seems to be in Owen's "Anatomy of Vertebrata," III., pages 798, 799, note. "I deeply regretted, therefore, to see in a 'Historical Sketch' of the Progress of Enquiry into the origin of species, prefixed to the fourth edition of that work (1866), that Mr. Darwin, after affirming inaccurately and without evidence, that I admitted Natural Selection to have done something toward that end, to wit, the 'origin of species,' proceeds to remark: 'It is surprising that this admission should not have been made earlier, as Prof. Owen now believes that he promulgated the theory of Natural Selection in a passage read before the Zoological Society in February, 1850, ("Trans." Volume IV., page 15).'" The first of the two passages quoted by Owen from the fourth edition of the "Origin" runs: "Yet he [Prof. Owen] at the same time admits that Natural Selection MAY [our italics] have done something towards this end." In the sixth edition of the "Origin," page xviii., Darwin, after referring to a correspondence in the "London Review" between the Editor of that Journal and Owen, goes on: "It appeared manifest to the editor, as well as to myself, that Prof. Owen claimed to have promulgated the theory of Natural Selection before I had done so;...but as far as it is possible to understand certain recently published passages (Ibid. ["Anat. of Vert."], Volume III., page 798), I have either partly or wholly again fallen into error. It is consolatory to me that others find Prof. Owen's controversial writings as difficult to understand and to reconcile with each other, as I do. As far as the mere enunciation of the principle of Natural Selection is concerned, it is quite immaterial whether or no Prof. Owen preceded me, for both of us, as shown in this historical sketch, were long ago preceded by Dr. Wells and Mr. Matthews.") LETTER 698. TO J.D. HOOKER. Down, December 29th, 1868. Your letter is quite invaluable, for Nageli's essay (698/1. See preceding Letter.) is so clever that it will, and indeed I know it has produced a great effect; so that I shall devote three or four pages to an answer. I have been particularly struck by your statements about erect and suspended ovules. You have given me heart, and I will fight my battle better than I should otherwise have done. I think I cannot resist throwing the contrivances in orchids into his teeth. You say nothing about the flowers of the rue. (698/2. For Ruta see "Origin," Edition V., page 154.) Ask your colleagues whether they know anything about the structure of the flower and ovarium in the uppermost flower. But don't answer on purpose. I have gone through my long Index of "Gardeners' Chronicle," which was made solely for my own use, and am greatly disappointed to find, as I fear, hardly anything which will be of use to you. (698/3. For Hooker's projected biological book, see Letter 696.) I send such as I have for the chance of their being of use. LETTER 699. TO J.D. HOOKER. Down, January 16th [1869]. Your two notes and remarks are of the utmost value, and I am greatly obliged to you for your criticism on the term. "Morphological" seems quite just, but I do not see how I can avoid using it. I found, after writing to you, in Vaucher about the Rue (699/1. "Plantes d'Europe," Volume I., page 559, 1841.), but from what you say I will speak more cautiously. It is the Spanish Chesnut that varies in divergence. Seeds named Viola nana were sent me from Calcutta by Scott. I must refer to the plants as an "Indian species," for though they have produced hundreds of closed flowers, they have not borne one perfect flower. (699/2. The cleistogamic flowers of Viola are used in the discussion on Nageli's views. See "Origin," Edition V., page 153.) You ask whether I want illustrations "of ovules differing in position in different flowers on the same plant." If you know of such cases, I should certainly much like to hear them. Again you speak of the angle of leaf-divergence varying and the variations being transmitted. Was the latter point put in in a hurry to round the sentence, or do you really know of cases? Whilst looking for notes on the variability of the divisions of the ovarium, position of the ovules, aestivation, etc., I found remarks written fifteen or twenty years ago, showing that I then supposed that characters which were nearly uniform throughout whole groups must be of high vital importance to the plants themselves; consequently I was greatly puzzled how, with organisms having very different habits of life, this uniformity could have been acquired through Natural Selection. Now, I am much inclined to believe, in accordance with the view given towards the close of my MS., that the near approach to uniformity in such structures depends on their not being of vital importance, and therefore not being acted on by Natural Selection. (699/3. This view is given in the "Origin," Edition VI., page 372.) If you have reflected on this point, what do you think of it? I hope that you approved of the argument deduced from the modifications in the small closed flowers. It is only about two years since last edition of "Origin," and I am fairly disgusted to find how much I have to modify, and how much I ought to add; but I have determined not to add much. Fleeming Jenkin has given me much trouble, but has been of more real use to me than any other essay or review. (699/4. On Fleeming Jenkin's review, "N. British Review," June, 1867, see "Life and Letters," III., page 107.) LETTER 700. TO J.D. HOOKER. Down [January 22nd, 1869]. Your letter is quite splenditious. I am greatly tempted, but shall, I hope, refrain from using some of your remarks in my chapter on Classification. It is very true what you say about unimportant characters being so important systematically; yet it is hardly paradoxical bearing in mind that the natural system is genetic, and that we have to discover the genealogies anyhow. Hence such parts as organs of generation are so useful for classification though not concerned with the manner of life. Hence use for same purpose of rudimentary organs, etc. You cannot think what a relief it is that you do not object to this view, for it removes PARTLY a heavy burden from my shoulders. If I lived twenty more years and was able to work, how I should have to modify the "Origin," and how much the views on all points will have to be modified! Well, it is a beginning, and that is something... LETTER 701. TO T.H. FARRER (Lord Farrer). Down, August 10th, 1869. Your view seems most ingenious and probable; but ascertain in a good many cases that the nectar is actually within the staminal tube. (701/1. It seems that Darwin did not know that the staminal tube in the diadelphous Leguminosae serves as a nectar-holder, and this is surprising, as Sprengel was aware of the fact.) One can see that if there is to be a split in the tube, the law of symmetry would lead it to be double, and so free one stamen. Your view, if confirmed, would be extremely well worth publication before the Linnean Society. It is to me delightful to see what appears a mere morphological character found to be of use. It pleases me the more as Carl Nageli has lately been pitching into me on this head. Hooker, with whom I discussed the subject, maintained that uses would be found for lots more structures, and cheered me by throwing my own orchids into my teeth. (701/2. See Letters 697-700.) All that you say about changed position of the peduncle in bud, in flower, and in seed, is quite new to me, and reminds me of analogous cases with tendrils. (701/3. See Vochting, "Bewegung der Bluthen und Fruchte," 1882; also Kerner, "Pflanzenleben," Volume I., page 494, Volume II., page 121.) This is well worth working out, and I dare say the brush of the stigma. With respect to the hairs or filaments (about which I once spoke) within different parts of flowers, I have a splendid Tacsonia with perfectly pendent flowers, and there is only a microscopical vestige of the corona of coloured filaments; whilst in most common passion-flowers the flowers stand upright, and there is the splendid corona which apparently would catch pollen. (701/4. Sprengel ("Entdeckte Geheimniss," page 164) imagined that the crown of the Passion-flower served as a nectar-guide and as a platform for insects, while other rings of filaments served to keep rain from the nectar. F. Muller, quoted in H. Muller ("Fertilisation," page 268), looks at the crowns of hairs, ridges in some species, etc., as gratings serving to imprison flies which attract the fertilising humming-birds. There is, we believe, no evidence that the corona catches pollen. See Letter 704, note.) On the lower side of corolla of foxglove there are some fine hairs, but these seem of not the least use (701/5. It has been suggested that the hairs serve as a ladder for humble bees; also that they serve to keep out "unbidden guests.")--a mere purposeless exaggeration of down on outside--as I conclude after watching the bees at work, and afterwards covering up some plants; for the protected flowers rarely set any seed, so that the hairy lower part of corolla does not come into contact with stigma, as some Frenchman says occurs with some other plants, as Viola odorata and I think Iris. I heartily wish I could accept your kind invitation, for I am not by nature a savage, but it is impossible. Forgive my dreadful handwriting, none of my womenkind are about to act as amanuensis. LETTER 702. TO WILLIAM C. TAIT. (702/1. Mr. Tait, to whom the following letter is addressed, was resident in Portugal. His kindness in sending plants of Drosophyllum lusitanicum is acknowledged in "Insectivorous Plants.") Down, March 12th, 1869. I have received your two letters of March 2nd and 5th, and I really do not know how to thank you enough for your extraordinary kindness and energy. I am glad to hear that the inhabitants notice the power of the Drosophyllum to catch flies, for this is the subject of my studies. (702/2. The natives are said to hang up plants of Drosophyllum in their cottages to act as fly-papers ("Insectivorous Plants," page 332).) I have observed during several years the manner in which this is effected, and the results produced in several species of Drosera, and in the wonderful American Dionoea, the leaves of which catch insects just like a steel rat-trap. Hence I was most anxious to learn how the Drosophyllum would act, so that the Director of the Royal Gardens at Kew wrote some years ago to Portugal to obtain specimens for me, but quite failed. So you see what a favour you have conferred on me. With Drosera it is nothing less than marvellous how minute a fraction of a grain of any nitrogenised matter the plant can detect; and how differently it behaves when matter, not containing nitrogen, of the same consistence, whether fluid or solid, is applied to the glands. It is also exquisitely sensitive to a weight of even the 1/70000 of a grain. From what I can see of the glands on Drosophyllum I suspect that I shall find only the commencement, or nascent state of the wonderful capacities of the Drosera, and this will be eminently interesting to me. My MS. on this subject has been nearly ready for publication during some years, but when I shall have strength and time to publish I know not. And now to turn to other points in your letter. I am quite ignorant of ferns, and cannot name your specimen. The variability of ferns passes all bounds. With respect to your Laugher Pigeons, if the same with the two sub-breeds which I kept, I feel sure from the structure of the skeleton, etc., that it is a descendant of C. livia. In regard to beauty, I do not feel the difficulty which you and some others experience. In the last edition of my "Origin" I have discussed the question, but necessarily very briefly. (702/3. Fourth Edition, page 238.) A new and I hope amended edition of the "Origin" is now passing through the press, and will be published in a month or two, and it will give me great pleasure to send you a copy. Is there any place in London where parcels are received for you, or shall I send it by post? With reference to dogs' tails, no doubt you are aware that a rudimentary stump is regularly inherited by certain breeds of sheep-dogs, and by Manx cats. You speak of a change in the position of the axis of the earth: this is a subject quite beyond me, but I believe the astronomers reject the idea. Nevertheless, I have long suspected that some periodical astronomical or cosmical cause must be the agent of the incessant oscillations of level in the earth's crust. About a month ago I suggested this to a man well capable of judging, but he could not conceive any such agency; he promised, however, to keep it in mind. I wish I had time and strength to write to you more fully. I had intended to send this letter off at once, but on reflection will keep it till I receive the plants. LETTER 703. TO H. MULLER. Down, March 14th, 1870. I think you have set yourself a new, very interesting, and difficult line of research. As far as I know, no one has carefully observed the structure of insects in relation to flowers, although so many have now attended to the converse relation. (703/1. See Letter 462, also H. Muller, "Fertilisation of Flowers," English Translation, page 30, on "The insects which visit flowers." In Muller's book references are given to several of his papers on this subject.) As I imagine few or no insects are adapted to suck the nectar or gather the pollen of any single family of plants, such striking adaptations can hardly, I presume, be expected in insects as in flowers. LETTER 704. TO T.H. FARRER (Lord Farrer). Down, May 28th, 1870. I suppose I must have known that the stamens recovered their former position in Berberis (704/1. See Farrer, "Nature," II., 1870, page 164. Lord Farrer was before H. Muller in making out the mechanism of the barberry.), for I formerly tried experiments with anaesthetics, but I had forgotten the facts, and I quite agree with you that it is a sound argument that the movement is not for self-fertilisation. The N. American barberries (Mahonia) offer a good proof to what an extent natural crossing goes on in this genus; for it is now almost impossible in this country to procure a true specimen of the two or three forms originally introduced. I hope the seeds of Passiflora will germinate, for the turning up of the pendent flower must be full of meaning. (704/2. Darwin had (May 12th, 1870) sent to Farrer an extract from a letter from F. Muller, containing a description of a Passiflora visited by humming-birds, in which the long flower-stalk curls up so that "the flower itself is upright." Another species visited by bees is described as having "dependent flowers." In a letter, June 29th, 1870, Mr. Farrer had suggested that P. princeps, which he described as having sub-erect flowers, is fitted for humming-birds' visits. In another letter, October 13th, 1869, he says that Tacsonia, which has pendent flowers and no corona, is not fertilised by insects in English glass-houses, and may be adapted for humming-birds. See "Life and Letters," III., page 279, for Farrer's remarks on Tacsonia and Passiflora; also H. Muller's "Fertilisation of Flowers," page 268, for what little is known on the subject; also Letter 701 in the present volume.) I am so glad that you are able to occupy yourself a little with flowers: I am sure it is most wise in you, for your own sake and children's sakes. Some little time ago Delpino wrote to me praising the Swedish book on the fertilisation of plants; as my son George can read a little Swedish, I should like to have it back for a time, just to hear a little what it is about, if you would be so kind as to return it by book-post. (704/3. Severin Axell, "Om anordningarna for de Fanerogama Vaxternas Befruktning," Stockholm, 1869.) I am going steadily on with my experiments on the comparative growth of crossed and self-fertilised plants, and am now coming to some very curious anomalies and some interesting results. I forget whether I showed you any of them when you were here for a few hours. You ought to see them, as they explain at a glance why Nature has taken such extraordinary pains to ensure frequent crosses between distinct individuals. If in the course of the summer you should feel any inclination to come here for a day or two, I hope that you will propose to do so, for we should be delighted to see you... LETTER 705. TO ASA GRAY. Down, December 7th, 1870. I have been very glad to receive your letter this morning. I have for some time been wishing to write to you, but have been half worked to death in correcting my uncouth English for my new book. (705/1. "Descent of Man.") I have been glad to hear of your cases appearing like incipient dimorphism. I believe that they are due to mere variability, and have no significance. I found a good instance in Nolana prostrata, and experimented on it, but the forms did not differ in fertility. So it was with Amsinckia, of which you told me. I have long thought that such variations afforded the basis for the development of dimorphism. I was not aware of such cases in Phlox, but have often admired the arrangement of the anthers, causing them to be all raked by an inserted proboscis. I am glad also to hear of your curious case of variability in ovules, etc. I said that I had been wishing to write to you, and this was about your Drosera, which after many fluctuations between life and death, at last made a shoot which I could observe. The case is rather interesting; but I must first remind you that the filament of Dionoea is not sensitive to very light prolonged pressure, or to nitrogenous matter, but is exquisitely sensitive to the slightest touch. (705/2. In another connection the following reference to Dionoea is of some interest: "I am sure I never heard of Curtis's observations on Dionoea, nor have I met with anything more than general statements about this plant or about Nepenthes catching insects." (From a letter to Sir J.D. Hooker, July 12th, 1860.)) In our Drosera the filaments are not sensitive to a slight touch, but are sensitive to prolonged pressure from the smallest object of any nature; they are also sensitive to solid or fluid nitrogenous matter. Now in your Drosera the filaments are not sensitive to a rough touch or to any pressure from non-nitrogenous matter, but are sensitive to solid or fluid nitrogenous matter. (705/3. Drosera filiformis: see "Insectivorous Plants," page 281. The above account does not entirely agree with Darwin's published statement. The filaments moved when bits of cork or cinder were placed on them; they did not, however, respond to repeated touches with a needle, thus behaving differently from D. rotundifolia. It should be remembered that the last-named species is somewhat variable in reacting to repeated touches.) Is it not curious that there should be such diversified sensitiveness in allied plants? I received a very obliging letter from Mr. Morgan, but did not see him, as I think he said he was going to start at once for the Continent. I am sorry to hear rather a poor account of Mrs. Gray, to whom my wife and I both beg to be very kindly remembered. LETTER 706. TO C.V. RILEY. (706/1. In Riley's opinion his most important work was the series entitled "Annual Report on the Noxious, Beneficial, and other Insects of the State of Missouri" (Jefferson City), beginning in 1869. These reports were greatly admired by Mr. Darwin, and his copies of them, especially of Nos. 3 and 4, show signs of careful reading.) Down, June 1st [1871]. I received some little time ago your report on noxious insects, and have now read the whole with the greatest interest. (706/2. "Third Annual Report on the Noxious, Beneficial, and other Insects of the State of Missouri" (Jefferson City, Mo.). The mimetic case occurs at page 67; the 1875 pupae of Pterophorus periscelidactylus, the "Grapevine Plume," have pupae either green or reddish brown, the former variety being found on the leaves, the latter on the brown stems of the vine.) There are a vast number of facts and generalisations of value to me, and I am struck with admiration at your powers of observation. The discussion on mimetic insects seems to me particularly good and original. Pray accept my cordial thanks for the instruction and interest which I have received. What a loss to Natural Science our poor mutual friend Walsh has been; it is a loss ever to be deplored... Your country is far ahead of ours in some respects; our Parliament would think any man mad who should propose to appoint a State Entomologist. LETTER 707A. TO C.V. RILEY. (706A/1. We have found it convenient to place the two letters to Riley together, rather than separate them chronologically.) Down, September 28th, 1881. I must write half a dozen lines to say how much interested I have been by your "Further Notes" on Pronuba which you were so kind as to send me. (706A/2. "Proc. Amer. Assoc. Adv. Sci." 1880.) I had read the various criticisms, and though I did not know what answer could be made, yet I felt full confidence in your result, and now I see that I was right...If you make any further observation on Pronuba it would, I think, be well worth while for you to observe whether the moth can or does occasionally bring pollen from one plant to the stigma of a distinct one (706A/3. Riley discovered the remarkable fact that the Yucca moth (Pronuba yuccasella) lays its eggs in the ovary of Yucca flowers, which it has previously pollinated, thus making sure of a supply of ovules for the larvae.), for I have shown that the cross-fertilisation of the flowers on the same plant does very little good; and, if I am not mistaken, you believe that Pronuba gathers pollen from the same flower which she fertilises. What interesting and beautiful observations you have made on the metamorphoses of the grasshopper-destroying insects. LETTER 707. TO F. HILDEBRAND. Down, February 9th [1872]. Owing to other occupations I was able to read only yesterday your paper on the dispersal of the seeds of Compositae. (707/1. "Ueber die Verbreitungsmittel der Compositenfruchte." "Bot. Zeitung," 1872, page 1.) Some of the facts which you mention are extremely interesting. I write now to suggest as worthy of your examination the curious adhesive filaments of mucus emitted by the achenia of many Compositae, of which no doubt you are aware. My attention was first called to the subject by the achenia of an Australian Pumilio (P. argyrolepis), which I briefly described in the "Gardeners' Chronicle," 1861, page 5. As the threads of mucus dry and contract they draw the seeds up into a vertical position on the ground. It subsequently occurred to me that if these seeds were to fall on the wet hairs of any quadruped they would adhere firmly, and might be carried to any distance. I was informed that Decaisne has written a paper on these adhesive threads. What is the meaning of the mucus so copiously emitted from the moistened seeds of Iberis, and of at least some species of Linum? Does the mucus serve as a protection against their being devoured, or as a means of attachment. (707/2. Various theories have been suggested, e.g., that the slime by anchoring the seed to the soil facilitates the entrance of the radicle into the soil: the slime has also been supposed to act as a temporary water-store. See Klebs in Pfeffer's "Untersuchungen aus dem Bot. Inst. zu Tubingen," I., page 581.) I have been prevented reading your paper sooner by attempting to read Dr. Askenasy's pamphlet, but the German is too difficult for me to make it all out. (707/3. E. Askenasy, "Beitrage zur Kritik der Darwin'schen Lehre." Leipzig, 1872.) He seems to follow Nageli completely. I cannot but think that both much underrate the utility of various parts of plants; and that they greatly underrate the unknown laws of correlated growth, which leads to all sorts of modifications, when some one structure or the whole plant is modified for some particular object. LETTER 708. TO T.H. FARRER. (Lord Farrer). (708/1. The following letter refers to a series of excellent observations on the fertilisation of Leguminosae, made by Lord Farrer in the autumn of 1869, in ignorance of Delpino's work on the subject. The result was published in "Nature," October 10th and 17th, 1872, and is full of interesting suggestions. The discovery of the mechanism in Coronilla mentioned in a note was one of the cases in which Lord Farrer was forestalled.) Down [1872]. I declare I am almost as sorry as if I had been myself forestalled--indeed, more so, for I am used to it. It is, however, a paramount, though bothersome duty in every naturalist to try and make out all that has been done by others on the subject. By all means publish next summer your confirmation and a summary of Delpino's observations, with any new ones of your own. Especially attend about the nectary exterior to the staminal tube. (708/2. This refers to a species of Coronilla in which Lord Farrer made the remarkable discovery that the nectar is secreted on the outside of the calyx. See "Nature," July 2nd, 1874, page 169; also Letter 715.) This will in every way be far better than writing to Delpino. It would not be at all presumptuous in you to criticise Delpino. I am glad you think him so clever; for so it struck me. Look at hind legs yourself of some humble and hive-bees; in former take a very big individual (if any can be found) for these are the females, the males being smaller, and they have no pollen-collecting apparatus. I do not remember where it is figured--probably in Kirby & Spence--but actual inspection better... Please do not return any of my books until all are finished, and do not hurry. I feel certain you will make fine discoveries. LETTER 709. TO T.H. FARRER. (Lord Farrer). Sevenoaks, October 13th, 1872. I must send you a line to say how extremely good your article appears to me to be. It is even better than I thought, and I remember thinking it very good. I am particularly glad of the excellent summary of evidence about the common pea, as it will do for me hereafter to quote; nocturnal insects will not do. I suspect that the aboriginal parent had bluish flowers. I have seen several times bees visiting common and sweet peas, and yet varieties, purposely grown close together, hardly ever intercross. This is a point which for years has half driven me mad, and I have discussed it in my "Var. of Animals and Plants under Dom." (709/1. In the second edition (1875) of the "Variation of Animals and Plants," Volume I., page 348, Darwin added, with respect to the rarity of spontaneous crosses in Pisum: "I have reason to believe that this is due to their stignas being prematurely fertilised in this country by pollen from the same flower." This explanation is, we think, almost certainly applicable to Lathyrus odoratus, though in Darwin's latest publication on the subject he gives reasons to the contrary. See "Cross and Self-Fertilisation," page 156, where the problem is left unsolved. Compare Letter 714 to Delpino. In "Life and Letters," III., page 261, the absence of cross-fertilisation is explained as due to want of perfect adaptation between the pea and our native insects. This is Hermann Muller's view: see his "Fertilisation of Flowers," page 214. See Letter 583, note.) I now suspect (and I wish I had strength to experimentise next spring) that from changed climate both species are prematurely fertilised, and therefore hardly ever cross. When artificially crossed by removal of own pollen in bud, the offspring are very vigorous. Farewell.--I wish I could compel you to go on working at fertilisation instead of so insignificant a subject as the commerce of the country! You pay me a very pretty compliment at the beginning of your paper. LETTER 710. TO J.D. HOOKER. (710/1. The following letters to Sir J.D. Hooker and the late Mr. Moggridge refer to Moggridge's observation that seeds stored in the nest of the ant Atta at Mentone do not germinate, though they are certainly not dead. Moggridge's observations are given in his book, "Harvesting Ants and Trap-Door Spiders," 1873, which is full of interesting details. The book is moreover remarkable in having resuscitated our knowledge of the existence of the seed-storing habit. Mr. Moggridge points out that the ancients were familiar with the facts, and quotes the well-known fable of the ant and the grasshopper, which La Fontaine borrowed from Aesop. Mr. Moggridge (page 5) goes on: "So long as Europe was taught Natural History by southern writers the belief prevailed; but no sooner did the tide begin to turn, and the current of information to flood from north to south, than the story became discredited." In Moggridge's "supplement" on the same subject, published in 1874, the author gives an account of his experiments made at Darwin's suggestion, and concludes (page 174) that "the vapour of formic acid is incapable of rendering the seeds dormant after the manner of the ants," and that indeed "its influence is always injurious to the seeds, even when present only in excessively minute quantities." Though unable to explain the method employed, he was convinced "that the non-germination of the seeds is due to some direct influence voluntarily exercised by the ants, and not merely to the conditions found in the nest" (page 172). See Volume I., Letter 251.) Down, February 21st [1873]. You have given me exactly the information which I wanted. Geniuses jump. I have just procured formic acid to try whether its vapour or minute drops will delay germination of fresh seeds; trying others at same time for comparison. But I shall not be able to try them till middle of April, as my despotic wife insists on taking a house in London for a month from the middle of March. I am glad to hear of the Primer (710/2. "Botany" (Macmillan's Science Primers).); it is not at all, I think, a folly. Do you know Asa Gray's child book on the functions of plants, or some such title? It is very good in giving an interest to the subject. By the way, can you lend me the January number of the "London Journal of Botany" for an article on insect-agency in fertilisation? LETTER 711. TO J. TRAHERNE MOGGRIDGE. Down, August 27th, 1873. I thank you for your very interesting letter, and I honour you for your laborious and careful experiments. No one knows till he tries how many unexpected obstacles arise in subjecting plants to experiments. I can think of no suggestions to make; but I may just mention that I had intended to try the effects of touching the dampened seeds with the minutest drop of formic acid at the end of a sharp glass rod, so as to imitate the possible action of the sting of the ant. I heartily hope that you may be rewarded by coming to some definite result; but I fail five times out of six in my own experiments. I have lately been trying some with poor success, and suppose that I have done too much, for I have been completely knocked up for some days. LETTER 712. TO J. TRAHERNE MOGGRIDGE. Down, March 10th, 1874. I am very sorry to hear that the vapour experiments have failed; but nothing could be better, as it seems to me, than your plan of enclosing a number of the ants with the seeds. The incidental results on the power of different vapours in killing seeds and stopping germination appear very curious, and as far as I know are quite new. P.S.--I never before heard of seeds not germinating except during a certain season; it will be a very strange fact if you can prove this. (712/1. Certain seeds pass through a resting period before germination. See Pfeffer's "Pflanzenphysiologie," Edition I., Volume II., page III.) LETTER 713. TO H. MULLER. Down, May 30th, 1873. I am much obliged for your letter received this morning. I write now chiefly to give myself the pleasure of telling you how cordially I admire the last part of your book, which I have finished. (713/1. "Die Befruchtung der Blumen durch Insekten": Leipzig, 1873. An English translation was published in 1883 by Prof. D'Arcy Thompson. The "Prefatory Notice" to this work (February 6th, 1882) is almost the last of Mr. Darwin's writings. See "Life and Letters," page 281.) The whole discussion seems to me quite excellent, and it has pleased me not a little to find that in the rough MS. of my last chapter I have arrived on many points at nearly the same conclusions that you have done, though we have reached them by different routes. (713/2. "The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom": London, 1876.) LETTER 714. TO F. DELPINO. Down, June 25th [1873]. I thank you sincerely for your letter. I am very glad to hear about Lathyrus odoratus, for here in England the vars. never cross, and yet are sometimes visited by bees. (714/1. In "Cross and Self-Fertilisation," page 156, Darwin quotes the information received from Delpino and referred to in the present letter--namely, that it is the fixed opinion of the Italian gardeners that the varieties do intercross. See Letter 709.) Pisum sativum I have also many times seen visited by Bombus. I believe the cause of the many vars. not crossing is that under our climate the flowers are self-fertilised at an early period, before the corolla is fully expanded. I shall examine this point with L. odoratus. I have read H. Muller's book, and it seems to me very good. Your criticism had not occurred to me, but is, I think just--viz. that it is much more important to know what insects habitually visit any flower than the various kinds which occasionally visit it. Have you seen A. Kerner's book "Schutzmittel des Pollens," 1873, Innsbruck. (714/2. Afterwards translated by Dr. Ogle as "Flowers and their Unbidden Guests," with a prefatory letter by Charles Darwin, 1878.) It is very interesting, but he does not seem to know anything about the work of other authors. I have Bentham's paper in my house, but have not yet had time to read a word of it. He is a man with very sound judgment, and fully admits the principle of evolution. I have lately had occasion to look over again your discussion on anemophilous plants, and I have again felt much admiration at your work. (714/3. "Atti della Soc. Italiana di Scienze Nat." Volume XIII.) (714/4. In the beginning of August, 1873, Darwin paid the first of several visits to Lord Farrer's house at Abinger. When sending copies of Darwin's letters for the "Life and Letters," Lord Farrer was good enough to add explanatory notes and recollections, from which we quote the following sketch.) "Above my house are some low hills, standing up in the valley, below the chalk range on the one hand and the more distant range of Leith Hill on the other, with pretty views of the valley towards Dorking in one direction and Guildford in the other. They are composed of the less fertile Greensand strata, and are covered with fern, broom, gorse, and heath. Here it was a particular pleasure of his to wander, and his tall figure, with his broad-brimmed Panama hat and long stick like an alpenstock, sauntering solitary and slow over our favourite walks, is one of the pleasantest of the many pleasant associations I have with the place." LETTER 715. TO T.H. FARRER (Lord Farrer). (715/1. The following note by Lord Farrer explains the main point of the letter, which, however, refers to the "bloom" problem as well as to Coronilla:-- "I thought I had found out what puzzled us in Coronilla varia: in most of the Papilionaceae, when the tenth stamen is free, there is nectar in the staminal tube, and the opening caused by the free stamen enables the bee to reach the nectar, and in so doing the bee fertilises the plant. In Coronilla varia, and in several other species of Coronilla, there is no nectar in the staminal tube or in the tube of the corolla. But there are peculiar glands with nectar on the outside of the calyx, and peculiar openings in the tube of the corolla through which the proboscis of the bee, whilst entering the flower in the usual way and dusting itself with pollen, can reach these glands, thus fertilising the plant in getting the nectar. On writing this to Mr. Darwin, I received the following characteristic note. The first postscript relates to the rough ground behind my house, over which he was fond of strolling. It had been ploughed up and then allowed to go back, and the interest was to watch how the numerous species of weeds of cultivation which followed the plough gradually gave way in the struggle for existence to the well-known and much less varied flora of an English common.") Bassett, Southampton, August 14th, 1873. You are the man to conquer a Coronilla. (715/2. In a former letter to Lord Farrer, Darwin wrote: "Here is a maxim for you, 'It is disgraceful to be beaten by a Coronilla.'") I have been looking at the half-dried flowers, and am prepared to swear that you have solved the mystery. The difference in the size of the cells on the calyx under the vexillum right down to the common peduncle is conspicuous. The flour still adhered to this side; I see little bracteae or stipules apparently with glandular ends at the base of the calyces. Do these secrete? It seems to me a beautiful case. When I saw the odd shape of the base of the vexillum, I concluded that it must have some meaning, but little dreamt what that was. Now there remains only the one serious point--viz.the separation of the one stamen. I daresay that you are right in that nectar was originally secreted within the staminal tube; but why has not the one stamen long since cohered? The great difference in structure for fertilisation within the same genus makes one believe that all such points are vary variable. (715/3. Coronilla emerus is of the ordinary papilionaceous type.) With respect to the non-coherence of the one stamen, do examine some flower-buds at a very early age; for parts which are largely developed are often developed to an unusual degree at a very early age, and it seems to me quite possible that the base of the vexillum (to which the single stamen adhered) might thus be developed, and thus keep it separate for a time from the other stamens. The cohering stamens to the right and left of the single one seem to me to be pushed out a little laterally. When you have finished your observations, you really ought to send an account with a diagram to "Nature," recalling your generalisation about the diadelphous structure, and now explaining the exception of Coronilla. (715/4. The observations were published in "Nature," Volume X., 1874, page 169.) Do add a remark how almost every detail of structure has a meaning where a flower is well examined. Your observations pleased me so much that I could not sit still for half an hour. Please to thank Mr. Payne (715/5. Lord Farrer's gardener.) for his remarks, which are of value to me, with reference to Mimosa. I am very much in doubt whether opening the sashes can act by favouring the evaporation of the drops; may not the movement of the leaves shake off the drops, or change their places? If Mr. Payne remembers any plant which is easily injured by drops, I wish he would put a drop or two on a leaf on a bright day, and cover the plant with a clean bell-glass, and do the same for another plant, but without a bell-glass over it, and observe the effects. Thank you much for wishing to see us again at Abinger, and it is very doubtful whether it will be Coronilla, Mr. Payne, the new garden, the children, E. [Lady Farrer], or yourself which will give me the most pleasure to see again. P.S. 1.--It will be curious to note in how many years the rough ground becomes quite uniform in its flora. P.S. 2.--One may feel sure that periodically nectar was secreted within the flower and then secreted by the calyx, as in some species of Iris and orchids. This latter being taken advantage of in Coronilla would allow of the secretion within the flower ceasing, and as this change was going on in the two secretions, all the parts of the flower would become modified and correlated. LETTER 716. TO J. BURDON SANDERSON. Down, Tuesday, September 9th [1873]. (716/1. Sir J. Burdon Sanderson showed that in Dionoea movement is accompanied by electric disturbances closely analogous to those occurring in muscle (see "Nature," 1874, pages 105, 127; "Proc. R. Soc." XXI., and "Phil. Trans." Volume CLXXIII., 1883, where the results are finally discussed).) I will send up early to-morrow two plants [of Dionoea] with five goodish leaves, which you will know by their being tied to sticks. Please remember that the slightest touch, even by a hair, of the three filaments on each lobe makes the leaf close, and it will not open for twenty-four hours. You had better put 1/4 in. of water into the saucers of the pots. The plants have been kept too cool in order to retard them. You had better keep them rather warm (i.e. temperature of warm greenhouse) for a day, and in a good light. I am extremely glad you have undertaken this subject. If you get a positive result, I should think you ought to publish it separately, and I could quote it; or I should be most glad to introduce any note by you into my account. I have no idea whether it is troublesome to try with the thermo-electric pile any change of temperature when the leaf closes. I could detect none with a common thermometer. But if there is any change of temperature I should expect it would occur some eight to twelve or twenty-four hours after the leaf has been given a big smashed fly, and when it is copiously secreting its acid digestive fluid. I forgot to say that, as far as I can make out, the inferior surface of the leaf is always in a state of tension, and that the contraction is confined to the upper surface; so that when this contraction ceases or suddenly fails (as by immersion in boiling water) the leaf opens again, or more widely than is natural to it. Whenever you have quite finished, I will send for the plants in their basket. My son Frank is staying at 6, Queen Anne Street, and comes home on Saturday afternoon, but you will not have finished by that time. P.S. I have repeated my experiment on digestion in Drosera with complete success. By giving leaves a very little weak hydrochloric acid, I can make them digest albumen--i.e. white of egg--quicker than they can do naturally. I most heartily thank you for all your kindness. I have been pretty bad lately, and must work very little. LETTER 717. TO J. BURDON SANDERSON. September 13th [1873]. How very kind it was of you to telegraph to me. I am quite delighted that you have got a decided result. Is it not a very remarkable fact? It seems so to me, in my ignorance. I wish I could remember more distinctly what I formerly read of Du Bois Raymond's results. My poor memory never serves me for more than a vague guide. I really think you ought to try Drosera. In a weak solution of phosphate of ammonia (viz. 1 gr. to 20 oz. of water) it will contract in about five minutes, and even more quickly in pure warm water; but then water, I suppose, would prevent your trial. I forget, but I think it contracts pretty quickly (i.e. in an hour or two) with a large drop of a rather stronger solution of the phosphate, or with an atom of raw meat on the disc of the leaf. LETTER 718. TO J.D. HOOKER. October 31st, 1873. Now I want to tell you, for my own pleasure, about the movements of Desmodium. 1. When the plant goes to sleep, the terminal leaflets hang vertically down, but the petioles move up towards the axis, so that the dependent leaves are all crowded round it. The little leaflets never go to sleep, and this seems to me very odd; they are at their games of play as late as 11 o'clock at night and probably later. (718/1. Stahl ("Botanische Zeitung," 1897, page 97) has suggested that the movements of the dwarf leaflets in Desmodium serve to shake the large terminal leaflets, and thus increase transpiration. According to Stahl's view their movement would be more useful at night than by day, because stagnation of the transpiration-current is more likely to occur at night.) 2. If the plant is shaken or syringed with tepid water, the terminal leaflets move down through about an angle of 45 deg, and the petioles likewise move about 11 deg downwards; so that they move in an opposite direction to what they do when they go to sleep. Cold water or air produces the same effect as does shaking. The little leaflets are not in the least affected by the plant being shaken or syringed. I have no doubt, from various facts, that the downward movement of the terminal leaflets and petioles from shaking and syringing is to save them from injury from warm rain. 3. The axis, the main petiole, and the terminal leaflets are all, when the temperature is high, in constant movement, just like that of climbing plants. This movement seems to be of no service, any more than the incessant movement of amoeboid bodies. The movement of the terminal leaflets, though insensible to the eye, is exactly the same as that of the little lateral leaflets--viz. from side to side, up and down, and half round their own axes. The only difference is that the little leaflets move to a much greater extent, and perhaps more rapidly; and they are excited into movement by warm water, which is not the case with the terminal leaflet. Why the little leaflets, which are rudimentary in size and have lost their sleep-movements and their movements from being shaken, should not only have retained, but have their spontaneous movements exaggerated, I cannot conceive. It is hardly credible that it is a case of compensation. All this makes me very anxious to examine some plant (if possible one of the Leguminosae) with either the terminal or lateral leaflets greatly reduced in size, in comparison with the other leaflets on the same leaf. Can you or any of your colleagues think of any such plant? It is indirectly on this account that I so much want the seeds of Lathyrus nissolia. I hear from Frank that you think that the absence of both lateral leaflets, or of one alone, is due to their having dropped off; I thought so at first, and examined extremely young leaves from the tips of the shoots, and some of them presented the same characters. Some appearances make me think that they abort by becoming confluent with the main petiole. I hear also that you doubt about the little leaflets ever standing not opposite to each other: pray look at the enclosed old leaf which has been for a time in spirits, and can you call the little leaflets opposite? I have seen many such cases on both my plants, though few so well marked. LETTER 719. TO J.D. HOOKER. Down, October 23rd [1873]. How good you have been about the plants; but indeed I did not intend you to write about Drosophyllum, though I shall be very glad to have a specimen. Experiments on other plants lead to fresh experiments. Neptunia is evidently a hopeless case. I shall be very glad of the other plants whenever they are ready. I constantly fear that I shall become to you a giant of bores. I am delighted to hear that you are at work on Nepenthes, and I hope that you will have good luck. It is good news that the fluid is acid; you ought to collect a good lot and have the acid analysed. I hope that the work will give you as much pleasure as analogous work has me. (719/1. Hooker's work on Nepenthes is referred to in "Insectivorous Plants," page 97: see also his address at the Belfast meeting of the British Association, 1874.) I do not think any discovery gave me more pleasure than proving a true act of digestion in Drosera. LETTER 720. TO J.D. HOOKER. Down, November 24th, 1873. I have been greatly interested by Mimosa albida, on which I have been working hard. Whilst your memory is pretty fresh, I want to ask a question. When this plant was most sensitive, and you irritated it, did the opposite leaflets shut up quite close, as occurs during sleep, when even a lancet could not be inserted between the leaflets? I can never cause the leaflets to come into contact, and some reasons make me doubt whether they ever do so except during sleep; and this makes me wish much to hear from you. I grieve to say that the plant looks more unhealthy, even, than it was at Kew. I have nursed it like the tenderest infant; but I was forced to cut off one leaf to try the bloom, and one was broken by the manner of packing. I have never syringed (with tepid water) more than one leaf per day; but if it dies, I shall feel like a murderer. I am pretty well convinced that I shall make out my case of movements as a protection against rain lodging on the leaves. As far as I have as yet made out, M. albida is a splendid case. I have had no time to examine more than one species of Eucalyptus. The seedlings of Lathyrus nissolia are very interesting to me; and there is something wonderful about them, unless seeds of two distinct leguminous species have got somehow mingled together. LETTER 721. TO W. THISELTON-DYER. Down, December 4th, 1873. As Hooker is so busy, I should be very much obliged if you could give me the name of the enclosed poor specimen of Cassia. I want much to know its name, as its power of movement, when it goes to sleep, is very remarkable. Linnaeus, I find, was aware of this. It twists each separate leaflet almost completely round (721/1. See "Power of Movement in Plants," Figure 154, page 370.), so that the lower surface faces the sky, at the same time depressing them all. The terminal leaflets are pointed towards the base of the leaf. The whole leaf is also raised up about 12 deg. When I saw that it possessed such complex powers of movement, I thought it would utilise its power to protect the leaflets from rain. Accordingly I syringed the plant for two minutes, and it was really beautiful to see how each leaflet on the younger leaves twisted its short sub-petiole, so that the blade was immediately directed at an angle between 45 and 90 deg to the horizon. I could not resist the pleasure of just telling you why I want to know the name of the Cassia. I should add that it is a greenhouse plant. I suppose that there will not be any better flowers till next summer or autumn. LETTER 722. TO T. BELT. (722/1. Belt's account, discussed in this letter, is probably that published in his "Naturalist in Nicaragua" (1874), where he describes "the relation between the presence of honey-secreting glands on plants, and the protection to the latter secured by the attendance of ants attracted by the honey." (Op. cit., pages 222 et seq.)) Thursday [1874?]. Your account of the ants and their relations seems to me to possess extraordinary interest. I do not doubt that the excretion of sweet fluid by the glands is in your cases of great advantage to the plants by means of the ants, but I cannot avoid believing that primordially it is a simple excretion, as occasionally occurs from the surface of the leaves of lime trees. It is quite possible that the primordial excretion may have been beneficially increased to serve the plant. In the common laurel [Prunus laurocerasus] of our gardens the hive-bees visit incessantly the glands of the young leaves, on their under sides; and I should altogether doubt whether their visits or the occasional visits of ants was of any service to the laurel. The stipules of the common vetch secrete largely during sunshine, and hive-bees collect the sweet fluid. So I think it is with the common bean. I am writing this away from home, and I have come away to get some rest, having been a good deal overworked. I shall read your book with great interest when published, but will not trouble you to send the MS., as I really have no spare strength or time. I believe that your book, judging by the chapter sent, will be extremely valuable. LETTER 723. TO J.D. HOOKER. (723/1. The following letter refers to Darwin's prediction as to the manner in which Hedychium (Zinziberaceae) is fertilised. Sir J.D. Hooker seems to have made inquiries in India in consequence of which Darwin received specimens of the moth which there visits the flower, unfortunately so much broken as to be useless (see "Life and Letters," III., page 284).) Down, March 25th [1874]. I am glad to hear about the Hedychium, and how soon you have got an answer! I hope that the wings of the Sphinx will hereafter prove to be bedaubed with pollen, for the case will then prove a fine bit of prophecy from the structure of a flower to special and new means of fertilisation. By the way, I suppose you have noticed what a grand appearance the plant makes when the green capsules open, and display the orange and crimson seeds and interior, so as to attract birds, like the pale buff flowers to attract dusk-flying lepidoptera. I presume you do not want seeds of this plant, as I have plenty from artificial fertilisation. (723/2. In "Nature," June 22nd, 1876, page 173, Hermann Muller communicated F. Muller's observation on the fertilisation of a bright-red-flowered species of Hedychium, which is visited by Callidryas, chiefly the males of C. Philea. The pollen is carried by the tips of the butterfly's wing, to which it is temporarily fixed by the slimy layer produced by the degeneration of the anther-wall. LETTER 724. TO W. THISELTON-DYER. Down, June 4th [1874]. I am greatly obliged to you about the Opuntia, and shall be glad if you can remember Catalpa. I wish some facts on the action of water, because I have been so surprised at a stream not acting on Dionoea and Drosera. (724/1. See Pfeffer, "Untersuchungen Bot. Inst. zu Tubingen," Bd. I., 1885, page 518. Pfeffer shows that in some cases--Drosera, for instance--water produces movement only when it contains fine particles in suspension. According to Pfeffer the stamens of Berberis, and the stigma of Mimulus, are both stimulated by gelatine, the action of which is, generally speaking, equivalent to that of water.) Water does not act on the stamens of Berberis, but it does on the stigma of Mimulus. It causes the flowers of the bedding-out Mesembryanthemum and Drosera to close, but it has not this effect on Gazania and the daisy, so I can make out no rule. I hope you are going on with Nepenthes; and if so, you will perhaps like to hear that I have just found out that Pinguicula can digest albumen, gelatine, etc. If a bit of glass or wood is placed on a leaf, the secretion is not increased; but if an insect or animal-matter is thus placed, the secretion is greatly increased and becomes feebly acid, which was not the case before. I have been astonished and much disturbed by finding that cabbage seeds excite a copious secretion, and am now endeavouring to discover what this means. (724/2. Clearly it had not occurred to Darwin that seeds may supply nitrogenous food as well as insects: see "Insectivorous Plants," page 390.) Probably in a few days' time I shall have to beg a little information from you, so I will write no more now. P.S. I heard from Asa Gray a week ago, and he tells me a beautiful fact: not only does the lid of Sarracenia secrete a sweet fluid, but there is a line or trail of sweet exudation down to the ground so as to tempt insects up. (724/3. A dried specimen of Sarracenia, stuffed with cotton wool, was sometimes brought from his study by Mr. Darwin, and made the subject of a little lecture to visitors of natural history tastes.) LETTER 725. TO W. THISELTON-DYER. Down, June 23rd, 1874. I wrote to you about a week ago, thanking you for information on cabbage seeds, asking you the name of Luzula or Carex, and on some other points; and I hope before very long to receive an answer. You must now, if you can, forgive me for being very troublesome, for I am in that state in which I would sacrifice friend or foe. I have ascertained that bits of certain leaves, for instance spinach, excite much secretion in Pinguicula, and that the glands absorb matter from the leaves. Now this morning I have received a lot of leaves from my future daughter-in-law in North Wales, having a surprising number of captured insects on them, a good many leaves, and two seed-capsules. She informs me that the little leaves had excited secretion; and my son and I have ascertained this morning that the protoplasm in the glands beneath the little leaves has undoubtedly undergone aggregation. Therefore, absurd as it may sound, I am prepared to affirm that Pinguicula is not only insectivorous, but graminivorous, and granivorous! Now I want to beg you to look under the simple microscope at the enclosed leaves and seeds, and, if you possibly can, tell me their genera. The little narrow leaves are remarkable (725/1. Those of Erica tetralix.); they are fleshy, with the edges much curled from the axis of the plant, and bear a few long glandular hairs; these grow in little tufts. These are the commonest in Pinguicula, and seem to afford most nutritious matter. A second leaf is like a miniature sycamore. With respect to the seeds, I suppose that one is a Carex; the other looks like that of Rumex, but is enclosed in a globular capsule. The Pinguicula grew on marshy, low, mountainous land. I hope you will think this subject sufficiently interesting to make you willing to aid me as far as you can. Anyhow, forgive me for being so very troublesome. LETTER 726. TO J.D. HOOKER. Down, August 30th [1874]. I am particularly obliged for your address. (726/1. Presidential address (Biological Section) at the Belfast meeting of the British Association, 1874.) It strikes me as quite excellent, and has interested me in the highest degree. Nor is this due to my having worked at the subject, for I feel sure that I should have been just as much struck, perhaps more so, if I had known nothing about it. You could not, in my opinion, have put the case better. There are several lights (besides the facts) in your essay new to me, and you have greatly honoured me. I heartily congratulate you on so splendid a piece of work. There is a misprint at page 7, Mitschke for Nitschke. There is a partial error at page 8, where you say that Drosera is nearly indifferent to organic substances. This is much too strong, though they do act less efficiently than organic with soluble nitrogenous matter; but the chief difference is in the widely different period of subsequent re-expansion. Thirdly, I did not suggest to Sanderson his electrical experiments, though, no doubt, my remarks led to his thinking of them. Now for your letter: you are very generous about Dionoea, but some of my experiments will require cutting off leaves, and therefore injuring plants. I could not write to Lady Dorothy [Nevill]. Rollisson says that they expect soon a lot from America. If Dionoea is not despatched, have marked on address, "to be forwarded by foot-messenger." Mrs. Barber's paper is very curious, and ought to be published (726/2. Mrs. Barber's paper on the pupa of Papilio Nireus assuming different tints corresponding to the objects to which it was attached, was communicated by Mr. Darwin to the "Trans. Entomolog. Soc." 1874.); but when you come here (and REMEMBER YOU OFFERED TO COME) we will consult where to send it. Let me hear when you recommence on Cephalotus or Sarracenia, as I think I am now on right track about Utricularia, after wasting several weeks in fruitless trials and observations. The negative work takes five times more time than the positive. LETTER 727. TO J.D. HOOKER. Down, September 18th [1874]. I have had a splendid day's work, and must tell you about it. Lady Dorothy sent me a young plant of U[tricularia] montana (727/1. See "Life and Letters," III., page 327, and "Insectivorous Plants," page 431.), which I fancy is the species you told me of. The roots or rhizomes (for I know not which they are; I can see no scales or internodes or absorbent hairs) bear scores of bladders from 1/20 to 1/100 of an inch in diameter; and I traced these roots to the depth of 1 1/2 in. in the peat and sand. The bladders are like glass, and have the same essential structure as those of our species, with the exception that many exterior parts are aborted. Internally the structure is perfect, as is the minute valvular opening into the bladder, which is filled with water. I then felt sure that they captured subterranean insects, and after a time I found two with decayed remnants, with clear proof that something had been absorbed, which had generated protoplasm. When you are here I shall be very curious to know whether they are roots or rhizomes. Besides the bladders there are great tuber-like swellings on the rhizomes; one was an inch in length and half in breadth. I suppose these must have been described. I strongly suspect that they serve as reservoirs for water. (727/2. The existence of water-stores is quite in accordance with the epiphytic habit of the plant.) But I shall experimentise on this head. A thin slice is a beautiful object, and looks like coarsely reticulated glass. If you have an old plant which could be turned out of its pot (and can spare the time), it would be a great gain to me if you would tear off a bit of the roots near the bottom, and shake them well in water, and see whether they bear these minute glass-like bladders. I should also much like to know whether old plants bear the solid bladder-like bodies near the upper surface of the pot. These bodies are evidently enlargements of the roots or rhizomes. You must forgive this long letter, and make allowance for my delight at finding this new sub-group of insect-catchers. Sir E. Tennent speaks of an aquatic species of Utricularia in Ceylon, which has bladders on its roots, and rises annually to the surface, as he says, by this means. (727/3. Utricularia stellaris. Emerson Tennent's "Ceylon," Volume I., page 124, 1859.) We shall be delighted to see you here on the 26th; if you will let us know your train we will send to meet you. You will have to work like a slave while you are here. LETTER 728. TO J. JENNER WEIR. (728/1. In 1870 Mr. Jenner Weir wrote to Darwin: "My brother has but two kinds of laburnum, viz., Cytisus purpureus, very erect, and Cytisus alpinus, very pendulous. He has several stocks of the latter grafted with the purple one; and this year, the grafts being two years old, I saw in one, fairly above the stock, about four inches, a raceme of purely yellow flowers with the usual dark markings, and above them a bunch of purely purple flowers; the branches of the graft in no way showed an intermediate character, but had the usual rigid growth of purpureus." Early in July 1875, when Darwin was correcting a new edition of "Variation under Domestication," he again corresponded with Mr. Weir on the subject.) Down, July 8th [1875]. I thank you cordially. The case interests me in a higher degree than anything which I have heard for a very long time. Is it your brother Harrison W., whom I know? I should like to hear where the garden is. There is one other very important point which I am most anxious to hear--viz., the nature of the leaves at the base of the yellow racemes, for leaves are always there produced with the yellow laburnums, and I suppose so in the case of C. purpureus. As the tree has produced yellow racemes several times, do you think you could ask your brother to cut off and send me by post in a box a small branch of the purple stock with the pods or leaves of the yellow sport? (728/2. "The purple stock" here means the supposed C. purpureus, on which a yellow-flowered branch was borne.) This would be an immense favour, for then I would cut the point of junction longitudinally and examine slice under the microscope, to be able to state no trace of bud of yellow kind having been inserted. I do not suspect anything of the kind, but it is sure to be said that your brother's gardener, either by accident or fraud, inserted a bud. Under this point of view it would be very good to gather from your brother how many times the yellow sport has appeared. The case appears to me so very important as to be worth any trouble. Very many thanks for all assistance so kindly given. I will of course send a copy of new edition of "Variation under Domestication" when published in the autumn. LETTER 729. TO J. JENNER WEIR. (729/1. On July 9th Mr. Weir wrote to say that a branch of the Cytisus had been despatched to Down. The present letter was doubtless written after Darwin had examined the specimen. In "Variation under Domestication," Edition II., Volume I., page 417, note, he gives for a case recorded in the "Gardeners' Chronicle" in 1857 the explanation here offered (viz. that the graft was not C. purpureus but C. Adami), and adds, "I have ascertained that this occurred in another instance." This second instance is doubtless Mr. Weir's.) Down, July 10th, 1875. I do not know how to thank you enough; pray give also my thanks and kind remembrances to your brother. I am sure you will forgive my expressing my doubts freely, as I well know that you desire the truth more than anything else. I cannot avoid the belief that some nurseryman has sold C[ytisus] Adami to your brother in place of the true C. purpureus. The latter is a little bush only 3 feet high (Loudon), and when I read your account, it seemed to me a physical impossibility that a sporting branch of C. alpinus could grow to any size and be supported on the extremely delicate branches of C. purpureus. If I understand rightly your letter, you consider the tuft of small shoots on one side of the sporting C. alpinus from Weirleigh as C. purpureus; but these shoots are certainly those of C. Adami. I earnestly beg you to look at the specimens enclosed. The branch of the true C. purpureus is the largest which I could find. If C. Adami was sold to your brother as C. purpureus, everything is explained; for then the gardener has grafted C. Adami on C. alpinus, and the former has sported in the usual manner; but has not sported into C. purpureus, only into C. alpinus. C. Adami does not sport less frequently into C. purpureus than into C. alpinus. Are the purple flowers borne on moderately long racemes? If so, the plant is certainly C. Adami, for the true C. purpureus bears flowers close to the branches. I am very sorry to be so troublesome, but I am very anxious to hear again from you. C. purpureus bears "flowers axillary, solitary, stalked." P.S.--I think you said that the purple [tree] at Weirleigh does not seed, whereas the C. purpureus seeds freely, as you may see in enclosed. C. Adami never produces seeds or pods. LETTER 730. TO E. HACKEL. (730/1. The following extract refers to Darwin's book on "Cross and Self-Fertilisation.") November 13th, 1875. I am now busy in drawing up an account of ten years' experiments in the growth and fertility of plants raised from crossed and self-fertilised flowers. It is really wonderful what an effect pollen from a distinct seedling plant, which has been exposed to different conditions of life, has on the offspring in comparison with pollen from the same flower or from a distinct individual, but which has been long subjected to the same conditions. The subject bears on the very principle of life, which seems almost to require changes in the conditions. LETTER 731. TO G.J. ROMANES. (731/1. The following extract from a letter to Romanes refers to Francis Darwin's paper, "Experiments on the Nutrition of Drosera rotundifolia." "Linn. Soc. Journ." [1878], published 1880, page 17.) August 9th [1876]. The second point which delights me, seeing that half a score of botanists throughout Europe have published that the digestion of meat by plants is of no use to them (a mere pathological phenomenon, as one man says!), is that Frank has been feeding under exactly similar conditions a large number of plants of Drosera, and the effect is wonderful. On the fed side the leaves are much larger, differently coloured, and more numerous; flower-stalks taller and more numerous, and I believe far more seed capsules,--but these not yet counted. It is particularly interesting that the leaves fed on meat contain very many more starch granules (no doubt owing to more protoplasm being first formed); so that sections stained with iodine, of fed and unfed leaves, are to the naked eye of very different colours. There, I have boasted to my heart's content, and do you do the same, and tell me what you have been doing. LETTER 732. TO J.D. HOOKER. Down, October 25th [1876]. If you can put the following request into any one's hands pray do so; but if not, ignore my request, as I know how busy you are. I want any and all plants of Hoya examined to see if any imperfect flowers like the one enclosed can be found, and if so to send them to me, per post, damp. But I especially want them as young as possible. They are very curious. I have examined some sent me from Abinger (732/1. Lord Farrer's house.), but they were a month or two too old, and every trace of pollen and anthers had disappeared or had never been developed. Yet a very fine pod with apparently good seed had been formed by one such flower. (732/2. The seeds did not germinate; see the account of Hoya carnosa in "Forms of Flowers," page 331.) LETTER 733. TO G.J. ROMANES. (733/1. Published in the "Life of Romanes," page 62.) Down, August 10th [1877]. When I went yesterday I had not received to-day's "Nature," and I thought that your lecture was finished. (733/2. Abstract of a lecture on "Evolution of Nerves and Nervo-Systems," delivered at the Royal Institution, May 25th, 1877. "Nature," July 19th, August 2nd, August 9th, 1877.) This final part is one of the grandest essays which I ever read. It was very foolish of me to demur to your lines of conveyance like the threads in muslin (733/3. "Nature," August 2nd, page 271.), knowing how you have considered the subject: but still I must confess I cannot feel quite easy. Everyone, I suppose, thinks on what he has himself seen, and with Drosera, a bit of meat put on any one gland on its disc causes all the surrounding tentacles to bend to this point, and here there can hardly be differentiated lines of conveyance. It seems to me that the tentacles probably bend to that point wherever a molecular wave strikes them, which passes through the cellular tissue with equal ease in all directions in this particular case. (733/4. Speaking generally, the transmission takes place more readily in the longitudinal direction than across the leaf: see "Insectivorous Plants," page 239.) But what a fine case that of the Aurelia is! (733/5. Aurelia aurita, one of the medusae. "Nature," pages 269-71.) LETTER 734. TO W. THISELTON-DYER. 6, Queen Anne Street [December 1876]. Tell Hooker I feel greatly aggrieved by him: I went to the Royal Society to see him for once in the chair of the Royal, to admire his dignity and enjoy it, and lo and behold, he was not there. My outing gave me much satisfaction, and I was particularly glad to see Mr. Bentham, and to see him looking so wonderfully well and young. I saw lots of people, and it has not done me a penny's worth of harm, though I could not get to sleep till nearly four o'clock. LETTER 735. TO D. OLIVER. Down, October, 13th [1876?]. You must be a clair-voyant or something of that kind to have sent me such useful plants. Twenty-five years ago I described in my father's garden two forms of Linum flavum (thinking it a case of mere variation); from that day to this I have several times looked, but never saw the second form till it arrived from Kew. Virtue is never its own reward: I took paper this summer to write to you to ask you to send me flowers, [so] that I might beg plants of this Linum, if you had the other form, and refrained, from not wishing to trouble you. But I am now sorry I did, for I have hardly any doubt that L. flavum never seeds in any garden that I have seen, because one form alone is cultivated by slips. (735/1. Id est, because, the plant being grown from slips, one form alone usually occurs in any one garden. It is also arguable that it is grown by slips because only one form is common, and therefore seedlings cannot be raised.) (736/1. The following five letters refer to Darwin's work on "bloom"--a subject on which he did not live to complete his researches:-- One of his earliest letters on this subject was addressed in August, 1873, to Sir Joseph Hooker (736/2. Published in "Life and Letters," III., page 339.): "I want a little information from you, and if you do not yourself know, please to enquire of some of the wise men of Kew. "Why are the leaves and fruit of so many plants protected by a thin layer of waxy matter (like the common cabbage), or with fine hair, so that when such leaves or fruit are immersed in water they appear as if encased in thin glass? It is really a pretty sight to put a pod of the common pea, or a raspberry, into water. I find several leaves are thus protected on the under surface and not on the upper. "How can water injure the leaves, if indeed this is at all the case?" On this latter point Darwin wrote to the late Lord Farrer: "I am now become mad about drops of water injuring leaves. Please ask Mr. Payne (736/3. Lord Farrer's gardener.) whether he believes, FROM HIS OWN EXPERIENCE, that drops of water injure leaves or fruit in his conservatories. It is said that the drops act as burning-glasses; if this is true, they would not be at all injurious on cloudy days. As he is so acute a man, I should very much like to hear his opinion. I remember when I grew hothouse orchids I was cautioned not to wet their leaves; but I never then thought on the subject." The next letter, though of later date than some which follow it, is printed here because it briefly sums his results and serves as guide to the letters dealing with the subject.) LETTER 736. TO W. THISELTON-DYER. (736/4. Published in "Life and Letters," III., page 341.) Down, September 5th [1877]. One word to thank you. I declare, had it not been for your kindness, we should have broken down. As it is we have made out clearly that with some plants (chiefly succulent) the bloom checks evaporation--with some certainly prevents attacks of insects; with SOME sea-shore plants prevents injury from salt water, and, I believe, with a few prevents injury from pure water resting on the leaves. This latter is as yet the most doubtful and the most interesting point in relation to the movements of plants. (736/5. Modern research, especially that of Stahl on transpiration ("Bot. Zeitung," 1897, page 71) has shown that the question is more complex than it appeared in 1877. Stahl's point of view is that moisture remaining on a leaf checks the transpiration-current; and by thus diminishing the flow of mineral nutriment interferes with the process of assimilation. Stahl's idea is doubtless applicable to the whole problem of bloom on leaves. For other references to bloom see letters 685, 689 and 693.) LETTER 737. TO J.D. HOOKER. Down, August 19th, 1873. The next time you walk round the garden ask Mr. Smith (737/1. Probably John Smith (1798-1888), for some years Curator, Royal Gardens, Kew.), or any of your best men, what they think about injury from watering during sunshine. One of your men--viz., Mr. Payne, at Abinger, who seems very acute--declares that you may water safely any plant out of doors in sunshine, and that you may do the same for plants under glass if the sashes are opened. This seems to me very odd, but he seems positive on the point, and acts on it in raising splendid grapes. Another good gardener maintains that it is only COLD water dripping often on the same point of a leaf that ever injures it. I am utterly perplexed, but interested on the point. Give me what you learn when you come to Down. I should like to hear what plants are believed to be most injured by being watered in sunshine, so that I might get such. I expect that I shall be utterly beaten, as on so many other points; but I intend to make a few experiments and observations. I have already convinced myself that drops of water do NOT act as burning lenses. LETTER 738. TO J.D. HOOKER. December 20th [1873]. I find that it is no use going on with my experiments on the evil effects of water on bloom-divested leaves. Either I erred in the early autumn or summer in some incomprehensible manner, or, as I suspect to be the case, water is only injurious to leaves when there is a good supply of actinic rays. I cannot believe that I am all in the wrong about the movements of the leaves to shoot off water. The upshot of all this is that I want to keep all the plants from Kew until the spring or early summer, as it is mere waste of time going on at present. LETTER 739. TO W. THISELTON-DYER. Down, July 22nd [1877]. Many thanks for seeds of the Malva and information about Averrhoa, which I perceived was sensitive, as A. carambola is said to be; and about Mimosa sensitiva. The log-wood [Haematoxylon] has interested me much. The wax is very easily removed, especially from the older leaves, and I found after squirting on the leaves with water at 95 deg, all the older leaves became coated, after forty-eight hours, in an astonishing manner with a black Uredo, so that they looked as if sprinkled with soot and water. But not one of the younger leaves was affected. This has set me to work to see whether the "bloom" is not a protection against parasites. As soon as I have ascertained a little more about the case (and generally I am quite wrong at first) I will ask whether I could have a very small plant, which should never be syringed with water above 60 deg, and then I suspect the leaves would not be spotted, as were the older ones on the plant, when it arrived from Kew, but nothing like what they were after my squirting. In an old note of yours (which I have just found) you say that you have a sensitive Schrankia: could this be lent me? I have had lent me a young Coral-tree (Erythrina), which is very sickly, yet shows odd sleep movements. I suppose I could buy one, but Hooker told me first to ask you for anything. Lastly, have you any seaside plants with bloom? I find that drops of sea-water corrode sea-kale if bloom is removed; also the var. littorum of Triticum repens. (By the way, my plants of the latter, grown in pots here, are now throwing up long flexible green blades, and it is very odd to see, ON THE SAME CULM, the rigid grey bloom-covered blades and the green flexible ones.) Cabbages, ill-luck to them, do not seem to be hurt by salt water. Hooker formerly told me that Salsola kali, a var. of Salicornia, one species of Suaeda, Euphorbia peplis, Lathyrus maritimus, Eryngium maritimum, were all glaucous and seaside plants. It is very improbable that you have any of these or of foreigners with the same attributes. God forgive me: I hope that I have not bored you greatly. By all the rules of right the leaves of the logwood ought to move (as if partially going to sleep) when syringed with tepid water. The leaves of my little plant do not move at all, and it occurs to me as possible, though very improbable, that it would be different with a larger plant with perhaps larger leaves. Would you some day get a gardener to syringe violently, with water kept in a hothouse, a branch on one of your largest logwood plants and observe [whether?] leaves move together towards the apex of leaf? By the way, what astonishing nonsense Mr. Andrew Murray has been writing about leaves and carbonic acid! I like to see a man behaving consistently... What a lot I have scribbled to you! (FIGURE 13. Leaf of Trifolium resupinatum (from a drawing by Miss Pertz).) LETTER 740. TO W. THISELTON-DYER. [August, 1877.] There is no end to my requests. Can you spare me a good plant (or even two) of Oxalis sensitiva? The one which I have (formerly from Kew) has been so maltreated that I dare not trust my results any longer. Please give the enclosed to Mr. Lynch. (740/1. Mr. Lynch, now Curator of the Cambridge Botanic Garden, was at this time in the R. Bot. Garden, Kew. Mr. Lynch described the movements of Averrhoa bilimbi in the "Linn. Soc. Journ," Volume XVI., page 231. See also "The Power of Movement in Plants," page 330.) The spontaneous movements of the Averrhoa are very curious. You sent me seeds of Trifolium resupinatum, and I have raised plants, and some former observations which I did not dare to trust have proved accurate. It is a very little fact, but curious. The half of the lateral leaflets (marked by a cross) on the lower side have no bloom and are wetted, whereas the other half has bloom and is not wetted, so that the two sides look different to the naked eye. The cells of the eipdermis appear of a different shape and size on the two sides of the leaf [Figure 13]. When we have drawings and measurements of cells made, and are sure of our facts, I shall ask you whether you know of any case of the same leaf differing histologically on the two sides, for Hooker always says you are a wonderful man for knowing what has been made out. (740/2. The biological meaning of the curious structure of the leaves of Trifolium resupinatum remains a riddle. The stomata and (speaking from memory) the trichomes differ on the two halves of the lateral leaflets.) LETTER 741. TO L. ERRERA. (741/1. Professor L. Errera, of Brussels wrote, as a student, to Darwin, asking permission to send the MS. of an essay by his friend S. Gevaert and himself on cross and self-fertilisation, and which was afterwards published in the "Bull. Soc. Bot. Belg." XVII., 1878. The terms xenogamy, geitonogamy, and autogamy were first suggested by Kerner in 1876; their definition will be found at page 9 of Ogle's translation of Kerner's "Flowers and their Unbidden Guests," 1878. In xenogamy the pollen comes from another PLANT; in geitonogamy from another FLOWER on the same PLANT; in autogamy from the androecium of the fertilised FLOWER. Allogamy embraces xenogamy and geitonogamy.) Down, October 4th, 1877. I have now read your MS. The whole has interested me greatly, and is very clearly written. I wish that I had used some such terms as autogamy, xenogamy, etc...I entirely agree with you on the a priori probability of geitonogamy being more advantageous than autogamy; and I cannot remember having ever expressed a belief that autogamy, as a general rule, was better than geitonogamy; but the cases recorded by me seem too strong not to make me suspect that there was some unknown advantage in autogamy. In one place I insert the caution "if this be really the case," which you quote. (741/2. See "Cross and Self-Fertilisation," pages 352, 386. The phrase referred to occurs in both passages; that on page 386 is as follows: "We have also seen reason to suspect that self-fertilisation is in some peculiar manner beneficial to certain plants; but if this be really the case, the benefit thus derived is far more than counterbalanced by a cross with a fresh stock or with a slightly different variety." Errera and Gevaert conclude (pages 79-80) that the balance of the available evidence is in favour of the belief that geitonogamy is intermediate, in effectiveness, between autogamy and xenogamy.) I shall be very glad to be proved to be altogether in error on this point. Accept my thanks for pointing out the bad erratum at page 301. I hope that you will experimentise on inconspicuous flowers (741/3. See Miss Bateson, "Annals of Botany," 1888, page 255, "On the Cross-Fertilisation of Inconspicuous Flowers:" Miss Bateson showed that Senecio vulgaris clearly profits by cross-fertilisation; Stellaria media and Capsella bursa-pastoris less certainly.); if I were not too old and too much occupied I would do so myself. Finally let me thank you for the kind manner in which you refer to my work, and with cordial good wishes for your success... LETTER 742. TO W. THISELTON-DYER. Down, October 9th, 1877. One line to thank you much about Mertensia. The former plant has begun to make new leaves, to my great surprise, so that I shall be now well supplied. We have worked so well with the Averrhoa that unless the second species arrives in a very good state it would be superfluous to send it. I am heartily glad that you and Mrs. Dyer are going to have a holiday. I will look at you as a dead man for the next month, and nothing shall tempt me to trouble you. But before you enter your grave aid me if you can. I want seeds of three or four plants (not Leguminosae or Cruciferae) which produce large cotyledons. I know not in the least what plants have large cotyledons. Why I want to know is as follows: The cotyledons of Cassia go to sleep, and are sensitive to a touch; but what has surprised me much is that they are in constant movement up and down. So it is with the cotyledons of the cabbage, and therefore I am very curious to ascertain how far this is general. LETTER 743. TO W. THISELTON-DYER. Down, October 11th [1877]. The fine lot of seeds arrived yesterday, and are all sown, and will be most useful. If you remember, pray thank Mr. Lynch for his aid. I had not thought of beech or sycamore, but they are now sown. Perhaps you may like to see a rough copy of the tracing of movements of one of the cotyledons of red cabbage, and you can throw it into the fire. A line joining the two cotyledons stood facing a north-east window, and the day was uniformly cloudy. A bristle was gummed to one cotyledon, and beyond it a triangular bit of card was fixed, and in front a vertical glass. A dot was made in the glass every quarter or half hour at the point where the end of the bristle and the apex of card coincided, and the dots were joined by straight lines. The observations were from 10 a.m. to 8.45 p.m. During this time the enclosed figure was described; but between 4 p.m. and 5.38 p.m. the cotyledon moved so that the prolonged line was beyond the limits of the glass, and the course is here shown by an imaginary dotted line. The cotyledon of Primula sinensis moved in closely analogous manner, as do those of a Cassia. Hence I expect to find such movements very general with cotyledons, and I am inclined to look at them as the foundation for all the other adaptive movements of leaves. They certainly are of the so-called sleep of plants. I hope I have not bothered you. Do not answer. I am all on fire at the work. I have had a short and very prosperous note from Asa Gray, who says Hooker is very prosperous, and both are tremendously hard at work. (743/1. "Hooker is coming over, and we are going in summer to the Rocky Mountains together, according to an old promise of mine." Asa Gray to G.F. Wright, May 24th, 1877 ("Letters of Asa Gray," II., page 666).) LETTER 744. TO H. MULLER. Down, January 1st [1878?]. I must write two or three lines to thank you cordially for your very handsome and very interesting review of my last book in "Kosmos," which I have this minute finished. (744/1. "Forms of Flowers," 1877. H. Muller's article is in "Kosmos," II., page 286.) It is wonderful how you have picked out everything important in it. I am especially glad that you have called attention to the parallelism between illegitimate offspring of heterostyled plants and hybrids. Your previous article in "Kosmos" seemed to me very important, but for some unknown reason the german was very difficult, and I was sadly overworked at the time, so that I could not understand a good deal of it. (744/2. "Kosmos," II., pages 11, 128. See "Forms of Flowers," Edition II., page 308.) But I have put it on one side, and when I have to prepare a new edition of my book I must make it out. It seems that you attribute such cases as that of the dioecious Rhamnus and your own of Valeriana to the existence of two forms with larger and smaller flowers. I cannot follow the steps by which such plants have been rendered dioecious, but when I read your article with more care I hope I shall understand. (744/3. See "Forms of Flowers," Edition II., pages 9 and 304. H. Muller's view is briefly that conspicuous and less conspicuous varieties occurred, and that the former were habitually visited first by insects; thus the less conspicuous form would play the part of females and their pollen would tend to become superfluous. See H. Muller in "Kosmos," II.) If you have succeeded in explaining this class of cases I shall heartily rejoice, for they utterly perplexed me, and I could not conjecture what their meaning was. It is a grievous evil to have no faculty for new languages. With the most sincere respect and hearty good wishes to you and all your family for the new year... P.S.--What interesting papers your wonderful brother has lately been writing! LETTER 745. TO W. THISELTON-DYER. (745/1. This letter refers to the purchase of instruments for the Jodrell Laboratory in the Royal Gardens, Kew. "The Royal Commission on Scientific Instruction and the Advancement of Science, commonly spoken of as the Devonshire Commission, in its fourth Report (1874), page 10, expressed the opinion that 'it is highly desirable that opportunities for the pursuit of investigations in Physiological Botany should be afforded at Kew to those persons who may be inclined to follow that branch of science.' Effect was given to this recommendation by the liberality of the late T.J. Phillips-Jodrell, M.A., who built and equipped the small laboratory, which has since borne his name, at his own expense. It was completed and immediately brought into use in 1876." The above is taken from the "Bulletin of Miscellaneous Information," R. Botanic Gardens, Kew, 1901, page 102, which also gives a list of work carried out in the laboratory between 1876 and 1900.) Down, March 14th, 1878. I have a very strong opinion that it would be the greatest possible pity if the Phys[iological] Lab., now that it has been built, were not supplied with as many good instruments as your funds can possibly afford. It is quite possible that some of them may become antiquated before they are much or even at all used. But this does not seem to me any argument at all against getting them, for the Laboratory cannot be used until well provided; and the mere fact of the instruments being ready may suggest to some one to use them. You at Kew, as guardians and promoters of botanical science, will then have done all in your power, and if your Lab. is not used the disgrace will lie at the feet of the public. But until bitter experience proves the contrary I will never believe that we are so backward. I should think the German laboratories would be very good guides as to what to get; but Timiriazeff of Moscow, who travelled over Europe to see all Bot. Labs., and who seemed so good a fellow, would, I should think, give the best list of the most indispensable instruments. Lately I thought of getting Frank or Horace to go to Cambridge for the use of the heliostat there; but our observations turned out of less importance than I thought, yet if there had been one at Kew we should probably have used it, and might have found out something curious. It is impossible for me to predict whether or not we should ever want this or that instrument, for we are guided in our work by what turns up. Thus I am now observing something about geotropism, and I had no idea a few weeks ago that this would have been necessary. In a short time we might earnestly wish for a centrifugal apparatus or a heliostat. In all such cases it would make a great difference if a man knew that he could use a particular instrument without great loss of time. I have now given my opinion, which is very decided, whether right or wrong, and Frank quite agrees with me. You can, of course, show this letter to Hooker. LETTER 746. TO F. LUDWIG. Down, May 29th, 1878. I thank you sincerely for the trouble which you have taken in sending me so long and interesting a letter, together with the specimens. Gradations are always very valuable, and you have been remarkably successful in discovering the stages by which the Plantago has become gyno-dioecious. (746/1. See F. Ludwig, "Zeitsch. f. d. Geo. Naturwiss." Bd. LII., 1879. Professor Ludwig's observations are quoted in the preface to "Forms of Flowers," Edition II., page ix.) Your view of its origin, from being proterogynous, seems to me very probable, especially as the females are generally the later-flowering plants. If you can prove the reverse case with Thymus your view will manifestly be rendered still more probable. I have never felt satisfied with H. Muller's view, though he is so careful and admirable an observer. (746/2. See "Forms of Flowers," Edition II., page 308. Also letter 744.) It is more than seventeen years since I attended to Plantago, and when nothing had been published on the subject, and in consequence I omitted to attend to several points; and now, after so long an interval, I cannot pretend to say to which of your forms the English one belongs; I well remember that the anther of the females contained a good deal [of] pollen, though not one sound grain. P.S.--Delpino is Professor of Botany in Genoa, Italy (746/3. Now at Naples.); I have always found him a most obliging correspondent. LETTER 747. TO W. THISELTON-DYER. Down, August 24th [1878]. Many thanks for seeds of Trifolium resupinatum, which are invaluable to us. I enclose seeds of a Cassia, from Fritz Muller, and they are well worth your cultivation; for he says they come from a unique, large and beautiful tree in the interior, and though looking out for years, he has never seen another specimen. One of the most splendid, largest and rarest butterflies in S. Brazil, he has never seen except near this one tree, and he has just discovered that its caterpillars feed on its leaves. I have just been looking at fine young pods beneath the ground of Arachis. (747/1. Arachis hypogoea, cultivated for its "ground nuts.") I suppose that the pods are not withdrawn when ripe from the ground; but should this be the case kindly inform me; if I do not hear I shall understand that [the] pods ripen and are left permanently beneath the ground. If you ever come across heliotropic or apheliotropic aerial roots on a plant not valuable (but which should be returned), I should like to observe them. Bignonia capreolata, with its strongly apheliotropic tendrils (which I had from Kew), is now interesting me greatly. Veitch tells me it is not on sale in any London nursery, as I applied to him for some additional plants. So much for business. I have received from the Geographical Soc. your lecture, and read it with great interest. (747/2. "On Plant-Distribution as a field for Geographical Research." "Geog. Soc. Proc." XXII., 1878, page 412.) But it ought not merely to be read; it requires study. The sole criticism which I have to make is that parts are too much condensed: but, good Lord, how rare a fault is this! You do not quote Saporta, I think; and some of his work on the Tertiary plants would have been useful to you. In a former note you spoke contemptuously of your lecture: all I can say is that I never heard any one speak more unjustly and shamefully of another than you have done of yourself! LETTER 748. TO H. MULLER. Down, September 20th, 1878. I am working away on some points in vegetable physiology, but though they interest me and my son, yet they have none of the fascination which the fertilisation of flowers possesses. Nothing in my life has ever interested me more than the fertilisation of such plants as Primula and Lythrum, or again Anacamptis (748/1. Orchis pyramidalis.) or Listera. LETTER 749. TO H. MULLER. Down, February 12th [1879]. I have just heard that some misfortune has befallen you, and that you have been treated shamefully. (749/1. Hermann Muller was accused by the Ultramontane party of introducing into his school-teaching crude hypotheses ("unreife Hypothesen"), which were assumed to have a harmful influence upon the religious sentiments of his pupils. Attempts were made to bring about Muller's dismissal, but the active hostility of his opponents, which he met in a dignified spirit, proved futile. ("Prof. Dr. Hermann Muller von Lippstadt. Ein Gedenkblatt," von Ernst Krause. "Kosmos," VII., page 393, 1883.)) I grieve deeply to hear this, and as soon as you can find a few minutes to spare, I earnestly beg you to let me hear what has happened. LETTER 750. TO A. STEPHEN WILSON. (750/1. The following letters refer to two forms of wheat cultivated in Russia under the names Kubanka and Saxonka, which had been sent to Mr. Darwin by Dr. Asher from Samara, and were placed in the hands of Mr. Wilson that he might test the belief prevalent in Russia that Kubanka "grown repeatedly on inferior soil," assumes "the form of Saxonka." Mr. Wilson's paper of 1880 gives the results of his inquiry. He concludes (basing his views partly on analogous cases and partly on his study of the Russian wheats) that the supposed transformation is explicable in chief part by the greater fertility of the Saxonka wheat leading to extermination of the other form. According to Mr. Wilson, therefore, the Saxonka survivors are incorrectly assumed to be the result of the conversion of one form into the other.) Down, April 24th, 1878. I send you herewith some specimens which may perhaps interest you, as you have so carefully studied the varieties of wheat. Anyhow, they are of no use to me, as I have neither knowledge nor time sufficient. They were sent me by the Governor of the Province of Samara, in Russia, at the request of Dr. Asher (son of the great Berlin publisher) who farmed for some years in the province. The specimen marked Kubanka is a very valuable kind, but which keeps true only when cultivated in fresh steppe-land in Samara, and in Saratoff. After two years it degenerates into the variety Saxonica, or its synonym Ghirca. The latter alone is imported into this country. Dr. Asher says that it is universally known, and he has himself witnessed the fact, that if grain of the Kubanka is sown in the same steppe-land for more than two years it changes into Saxonica. He has seen a field with parts still Kubanka and the remainder Saxonica. On this account the Government, in letting steppe-land, contracts that after two years wheat must not be sown until an interval of eight years. The ears of the two kinds appear different, as you will see, but the chief difference is in the quality of the grains. Dr. Asher has witnessed sales of equal weights of Kubanka and Saxonica grain, and the price of the former was to that of the latter as 7 to 4. The peasants say that the change commences in the terminal grain of the ear. The most remarkable point, as Dr. Asher positively asserts, is that there are no intermediate varieties; but that a grain produces a plant yielding either true Kubanka or true Saxonica. He thinks that it would be interesting to sow here both kinds in good and bad wheat soil and observe the result. Should you think it worth while to make any such trial, and should you require further information, Dr. Asher, whose address I enclose, will be happy to give any in his power. LETTER 751. TO A. STEPHEN WILSON. Basset, Southampton, April 29th [1878]. Your kind note and specimens have been forwarded to me here, where I am staying at my son's house for a fortnight's complete rest, which I required from rather too hard work. For this reason I will not now examine the seeds, but will wait till returning home, when, with my son Francis' aid, I will look to them. I always felt, though without any good reason, rather sceptical about Prof. Buckman's experiment, and I afterwards heard that a most wicked and cruel trick had been played on him by some of the agricultural students at Cirencester, who had sown seeds unknown to him in his experimental beds. Whether he ever knew this I did not hear. I am exceedingly glad that you are willing to look into the Russian wheat case. It may turn out a mare's nest, but I have often incidentally observed curious facts when making what I call "a fool's experiment." LETTER 752. TO A. STEPHEN WILSON. Down, March 5th, 1879. I have just returned home after an absence of a week, and your letter was not forwarded to me; I mention this to account for my apparent discourtesy in not having sooner thanked you. You have worked out the subject with admirable care and clearness, and your drawings are beautiful. I suspected that there was some error in the Russian belief, but I did not think of the explanation which you have almost proved to be the true one. It is an extremely interesting instance of a more fertile variety beating out a less fertile one, and, in this case, one much more valuable to man. With respect to publication, I am at a loss to advise you, for I live a secluded life and do not see many periodicals, or hear what is done at the various societies. It seems to me that your paper should be published in some agricultural journal; for it is not simply scientific, and would therefore not be published by the Linnean or Royal Societies. Would the Royal Agricultural Society be a fitting place? Unfortunately I am not a member, and could not myself present it. Unless you think of some better journal, there is the "Agricultural Gazette": I have occasionally suggested articles for publication to the editor (though personally unknown to me) which he has always accepted. Permit me again to thank you for the thorough manner in which you have worked out this case; to kill an error is as good a service as, and sometimes even better than, the establishing a new truth or fact. LETTER 753. TO A. STEPHEN WILSON. Down, February 13th, 1880. It was very kind of you to send me two numbers of the "Gardeners' Chronicle" with your two articles, which I have read with much interest. (753/1. "Gardeners' Chronicle," 1879, page 652; 1880, pages 108, 173.) You have quite convinced me, whatever Mr. Asher may say to the contrary. I want to ask you a question, on the bare chance of your being able to answer it, but if you cannot, please do not take the trouble to write. The lateral branches of the silver fir often grow out into knobs through the action of a fungus, Aecidium; and from these knobs shoots grow vertically (753/2. The well-known "Witches-Brooms," or "Hexen-Besen," produced by the fungus Aecidium elatinum.) instead of horizontally, like all the other twigs on the same branch. Now the roots of Cruciferae and probably other plants are said to become knobbed through the action of a fungus: now, do these knobs give rise to rootlets? and, if so, do they grow in a new or abnormal direction? (753/3. The parasite is probably Plasmodiophora: in this case no abnormal rootlets have been observed, as far as we know.) LETTER 754. TO W. THISELTON-DYER. Down, June 18th, 1879. The plants arrived last night in first-rate order, and it was very very good of you to take so much trouble as to hunt them up yourself. They seem exactly what I wanted, and if I fail it will not be for want of perfect materials. But a confounded painter (I beg his pardon) comes here to-night, and for the next two days I shall be half dead with sitting to him; but after then I will begin to work at the plants and see what I can do, and very curious I am about the results. I have to thank you for two very interesting letters. I am delighted to hear, and with surprise, that you care about old Erasmus D. God only knows what I shall make of his life--it is such new kind of work to me. (754/1. "Erasmus Darwin." By Ernst Krause. Translated from the German by W.S. Dallas: with a preliminary notice by Charles Darwin. London, 1879. See "Life and Letters," III., pages 218-20.) Thanks for case of sleeping Crotalaria--new to me. I quite agree to every word you say about Ball's lecture (754/2. "On the Origin of the Flora of the European Alps," "Geogr. Soc. Proc." Volume I., 1879, page 564. See Letter 395, Volume II.)--it is, as you say, like Sir W. Thomson's meteorite. (754/3. In 1871 Lord Kelvin (Presidential Address Brit. Assoc.) suggested that meteorites, "the moss-grown fragments from the ruins of another world," might have introduced life to our planet.) It is really a pity; it is enough to make Geographical Distribution ridiculous in the eyes of the world. Frank will be interested about the Auriculas; I never attended to this plant, for the powder did [not] seem to me like true "bloom." (754/4. See Francis Darwin, on the relation between "bloom" on leaves and the distribution of the stomata. "Linn. Soc. Journ." Volume XXII., page 114.) This subject, however, for the present only, has gone to the dogs with me. I am sorry to hear of such a struggle for existence at Kew; but I have often wondered how it is that you are all not killed outright. I can most fully sympathise with you in your admiration of your little girl. There is nothing so charming in this world, and we all in this house humbly adore our grandchild, and think his little pimple of a nose quite beautiful. LETTER 755. TO G. BENTHAM. Down, February 16th, 1880. I have had real pleasure in signing Dyer's certificate. (755/1. As a candidate for the Royal Society.) It was very kind in you to write to me about the Orchideae, for it has pleased me to an extreme degree that I could have been of the least use to you about the nature of the parts. They are wonderful creatures, these orchids, and I sometimes think with a glow of pleasure, when I remember making out some little point in their method of fertilisation. (755/2. Published in "Life and Letters," III., page 288.) With respect to terms, no doubt you will be able to improve them greatly, for I knew nothing about the terms as used in other groups of plants. Could you not invent some quite new term for gland, implying viscidity? or append some word to gland. I used for cirripedes "cement gland." Your present work must be frightfully difficult. I looked at a few dried flowers, and could make neither heads nor tails of them; and I well remember wondering what you would do with them when you came to the group in the "Genera Plantarum." I heartily wish you safe through your work,... LETTER 756. TO F.M. BALFOUR. Down, September 4th, 1880. I hope that you will not think me a great bore, but I have this minute finished reading your address at the British Association; and it has interested me so much that I cannot resist thanking you heartily for the pleasure derived from it, not to mention the honour which you have done me. (756/1. Presidential address delivered by Prof. F.M. Balfour before the Biological Section at the British Association meeting at Swansea (1880).) The recent progress of embryology is indeed splendid. I have been very stupid not to have hitherto read your book, but I have had of late no spare time; I have now ordered it, and your address will make it the more interesting to read, though I fear that my want of knowledge will make parts unintelligible to me. (756/2. "A Treatise on Comparative Embryology," 2 volumes. London, 1880.) In my recent work on plants I have been astonished to find to how many very different stimuli the same small part--viz., the tip of the radicle--is sensitive, and has the power of transmitting some influence to the adjoining part of the radicle, exciting it to bend to or from the source of irritation according to the needs of the plant (756/3. See Letter 757.); and all this takes place without any nervous system! I think that such facts should be kept in mind when speculating on the genesis of the nervous system. I always feel a malicious pleasure when a priori conclusions are knocked on the head: and therefore I felt somewhat like a devil when I read your remarks on Herbert Spencer (756/4. Prof. Balfour discussed Mr. Herbert Spencer's views on the genesis of the nervous system, and expressed the opinion that his hypothesis was not borne out by recent discoveries. "The discovery that nerves have been developed from processes of epithelial cells gives a very different conception of their genesis to that of Herbert Spencer, which makes them originate from the passage of nervous impulses through a track of mingled colloids..." (loc. cit., page 644.))...Our recent visit to Cambridge was a brilliant success to us all, and will ever be remembered by me with much pleasure. LETTER 757. TO JAMES PAGET. (757/1. During the closing years of his life, Darwin began to experimentise on the possibility of producing galls artificially. A letter to Sir J.D. Hooker (November 3rd, 1880) shows the interest which he felt in the question:-- "I was delighted with Paget's essay (757/2. An address on "Elemental Pathology," delivered before the British Medical Association, August 1880, and published in the Journal of the Association.); I hear that he has occasionally attended to this subject from his youth...I am very glad he has called attention to galls: this has always seemed to me a profoundly interesting subject; and if I had been younger would take it up." His interest in this subject was connected with his ever-present wish to learn something of the causes of variation. He imagined to himself wonderful galls caused to appear on the ovaries of plants, and by these means he thought it possible that the seed might be influenced, and thus new varieties arise. (757/3. There would have been great difficulties about this line of research, for when the sexual organs of plants are deformed by parasites (in the way he hoped to effect by poisons) sterility almost always results. See Molliard's "Les Cecidies Florales," "Ann. Sci. Nat." 1895, Volume I., page 228.) He made a considerable number of experiments by injecting various reagents into the tissues of leaves, and with some slight indications of success. (757/4. The above passage is reprinted, with alterations, from "Life and Letters," III., page 346.) The following letter to the late Sir James Paget refers to the same subject.) Down, November 14th, 1880. I am very much obliged for your essay, which has interested me greatly. What indomitable activity you have! It is a surprising thought that the diseases of plants should illustrate human pathology. I have the German "Encyclopaedia," and a few weeks ago told my son Francis that the article on the diseases of plants would be well worth his study; but I did not know it was written by Dr. Frank, for whom I entertain a high respect as a first-rate observer and experimentiser, though for some unknown reason he has been a good deal snubbed in Germany. I can give you one good case of regrowth in plants, recently often observed by me, though only externally, as I do not know enough of histology to follow out details. It is the tip of the radicle of a germinating common bean. The case is remarkable in some respects, for the tip is sensitive to various stimuli, and transmits an order, causing the upper part of the radicle to bend. When the tip (for a length of about 1 mm.) is cut transversely off, the radicle is not acted on by gravitation or other irritants, such as contact, etc., etc., but a new tip is regenerated in from two to four days, and then the radicle is again acted on by gravitation, and will bend to the centre of the earth. The tip of the radicle is a kind of brain to the whole growing part of the radicle! (757/5. We are indebted to Mr. Archer-Hind for the translation of the following passage from Plato ("Timaeus," 90A): "The reason is every man's guardian genius (daimon), and has its habitation in our brain; it is this that raises man (who is a plant, not of earth but of heaven) to an erect posture, suspending the head and root of us from the heavens, which are the birthplace of our soul, and keeping all the body upright." On the perceptions of plants, see "Nature," November 14th, 1901--a lecture delivered at the Glasgow meeting of the British Association by Francis Darwin. See also Bonitz, "Index Aristotelicus," S.V. phuton.) My observation will be published in about a week's time, and I would have sent you the book, but I do not suppose that there is anything else in the book which would interest you. I am delighted that you have drawn attention to galls. They have always seemed to me profoundly interesting. Many years ago I began (but failed for want of time, strength, and health, as on infinitely many other occasions) to experimentise on plants, by injecting into their tissues some alkaloids and the poison of wasps, to see if I could make anything like galls. If I remember rightly, in a few cases the tissues were thickened and hardened. I began these experiments because if by different poisons I could have affected slightly and differently the tissues of the same plant, I thought there would be no insuperable difficulty in the fittest poisons being developed by insects so as to produce galls adapted for them. Every character, as far as I can see, is apt to vary. Judging from one of your sentences you will smile at this. To any one believing in my pangenesis (if such a man exists) there does not seem to me any extreme difficulty in understanding why plants have such little power of regeneration; for there is reason to think that my imaginary gemmules have small power of passing from cell to cell. (757/6. On regeneration after injury, see Massart, "La Cicatrisation chez les Vegetaux," in Volume 57 (1898) of the "Memoires Couronnes," published by the Royal Academy of Belgium. An account of the literature is given by the author.) Forgive me for scribbling at such unreasonable length; but you are to blame for having interested me so much. P.S.--Perhaps you may remember that some two years ago you asked me to lunch with you, and proposed that I should offer myself again. Whenever I next come to London, I will do so, and thus have the pleasure of seeing you. LETTER 758. TO W. THISELTON-DYER. (758/1. "The Power of Movement in Plants" was published early in November, 1880. Sir W. Thiselton-Dyer, in writing to thank Darwin for a copy of the book, had (November 20th) compared a structure in the seedling Welwitschia with the "peg" of Cucurbita (see "Power of Movement," page 102). Dyer wrote: "One peculiar feature in the germinating embryo is a lateral hypocotyledonary process, which eventually serves as an absorbent organ, by which the nutriment of the endosperm is conveyed to the seedling. Such a structure was quite new to me, and Bower and I were disposed to see in it a representative of the foot in Selaginella, when I saw the account of Flahault's 'peg.'" Flahault, it should be explained, was the discoverer of the curious peg in Cucurbita. Prof. Bower wrote a paper ("On the Germination and Histology of the seedling of Welwitschia mirabilis" in the "Quart. Journ. Microscop. Sci." XXI., 1881, page 15.) Down, November 28th [1880]. Very many thanks for your most kind note, but you think too highly of our work--not but what this is very pleasant. I am deeply interested about Welwitschia. When at work on the pegs or projections I could not imagine how they were first developed, before they could have been of mere mechanical use. Now it seems possible that a circle between radicle and hypocotyl may be permeable to fluids, and thus have given rise to projections so as to expose larger surface. Could you test Welwitschia with permanganate of potassium: if, like my pegs, the lower surface would be coloured brown like radicle, and upper surface left white like hypocotyl. If such an idea as yours, of an absorbing organ, had ever crossed my mind, I would have tried many hypocotyls in weak citrate of ammonia, to see if it penetrated on line of junction more easily than elsewhere. I daresay the projection in Abronia and Mirabilis may be an absorbent organ. It was very good fun bothering the seeds of Cucurbita by planting them edgeways, as would never naturally occur, and then the peg could not act properly. Many of the Germans are very contemptuous about making out use of organs; but they may sneer the souls out of their bodies, and I for one shall think it the most interesting part of natural history. Indeed, you are greatly mistaken if you doubt for one moment on the very great value of your constant and most kind assistance to us. I have not seen the pamphlet, and shall be very glad to keep it. Frank, when he comes home, will be much interested and pleased with your letter. Pray give my kindest remembrance to Mrs. Dyer. This is a very untidy note, but I am very tired with dissecting worms all day. Read the last chapter of our book, and then you will know the whole contents. LETTER 759. TO H. VOCHTING. Down, December 16th, 1880. Absence from home has prevented me from sooner thanking you for your kind present of your several publications. I procured some time ago your "Organbilding" (759/1. "Organbildung im Pflanzenreich," 1878.) etc., but it was too late for me to profit by it for my book, as I was correcting the press. I read only parts, but my son Francis read the whole with care and told me much about it, which greatly interested me. I also read your article in the "Bot. Zeitung." My son began at once experimenting, to test your views, and this very night will read a paper before the Linnean Society on the roots of Rubus (759/2. Francis Darwin, "The Theory of the Growth of Cuttings" ("Linn. Soc. Journ." XVIII.). [I take this opportunity of expressing my regret that at page 417, owing to neglect of part of Vochting's facts, I made a criticism of his argument which cannot be upheld.--F.D.].), and I think that you will be pleased to find how well his conclusions agree with yours. He will of course send you a copy of his paper when it is printed. I have sent him your letter, which will please him if he agrees with me; for your letter has given me real pleasure, and I did not at all know what the many great physiologists of Germany, Switzerland, and Holland would think of it ["The Power of Movement," etc.]. I was quite sorry to read Sachs' views about root-forming matter, etc., for I have an unbounded admiration for Sachs. In this country we are dreadfully behind in Physiological Botany. LETTER 760. TO A. DE CANDOLLE. Down, January 24th, 1881. It was extremely kind of you to write me so long and valuable a letter, the whole of which deserves careful consideration. I have been particularly pleased at what you say about the new terms used, because I have often been annoyed at the multitude of new terms lately invented in all branches of Biology in Germany; and I doubted much whether I was not quite as great a sinner as those whom I have blamed. When I read your remarks on the word "purpose" in your "Phytographie," I vowed that I would not use it again; but it is not easy to cure oneself of a vicious habit. It is also difficult for any one who tries to make out the use of a structure to avoid the word purpose. I see that I have probably gone beyond my depth in discussing plurifoliate and unifoliate leaves; but in such a case as that of Mimosa albida, where rudiments of additional leaflets are present, we must believe that they were well developed in the progenitor of the plant. So again, when the first true leaf differs widely in shape from the older leaves, and resembles the older leaves in allied species, is it not the most simple explanation that such leaves have retained their ancient character, as in the case of the embryos of so many animals? Your suggestion of examining the movements of vertical leaves with an equal number of stomata on both sides, with reference to the light, seems to me an excellent one, and I hope that my son Francis may follow it up. But I will not trouble you with any more remarks about our book. My son will write to you about the diagram. Let me add that I shall ever remember with pleasure your visit here last autumn. LETTER 761. TO J. LUBBOCK (Lord Avebury). Down, April 16th [1881]. Will you be so kind as to send and lend me the Desmodium gyrans by the bearer who brings this note. Shortly after you left I found my notice of the seeds in the "Gardeners' Chronicle," which please return hereafter, as I have no other copy. (761/1. "Note on the Achenia of Pumilio argyrolepis." "Gardeners' Chronicle," 1861, page 4.) I do not think that I made enough about the great power of absorption of water by the corolla-like calyx or pappus. It seems to me not unlikely that the pappus of other Compositae may be serviceable to the seeds, whilst lying on the ground, by absorbing the dew which would be especially apt to condense on the fine points and filaments of the pappus. Anyhow, this is a point which might be easily investigated. Seeds of Tussilago, or groundsel (761/2. It is not clear whether Tussilago or groundsel (Senecio vulgaris) is meant; or whether he was not sure which of the two plants becomes slimy when wetted.), emit worm-like masses of mucus, and it would be curious to ascertain whether wetting the pappus alone would suffice to cause such secretion. (761/3. See Letter 707.) LETTER 762. TO G.J. ROMANES. Down, April 18th, 1881. I am extremely glad of your success with the flashing light. (762/1. Romanes' paper on the effect of intermittent light on heliotropism was the "Proc. Royal Soc." Volume LIV., page 333.) If plants are acted on by light, like some of the lower animals, there is an additional point of interest, as it seems to me, in your results. Most botanists believe that light causes a plant to bend to it in as direct a manner as light affects nitrate of silver. I believe that it merely tells the plant to which side to bend, and I see indications of this belief prevailing even with Sachs. Now it might be expected that light would act on a plant in something the same manner as on the lower animals. As you are at work on this subject, I will call your attention to another point. Wiesner, of Vienna (who has lately published a great book on heliotropism) finds that an intermittent light, say of 20 minutes, produces the same effect as a continuous light of, say 60 m. (762/2. Wiesner's papers on heliotropism are in the "Denkschriften" of the Vienna Academy, Volumes 39 and 43.) So that Van Tieghem, in the first part of his book which has just appeared, remarks, the light during 40 m. out of the 60 m. produced no effect. I observed an analogous case described in my book. (762/3. "Power of Movement," page 459.) Wiesner and Van Tieghem seem to think that this is explained by calling the whole process "induction," borrowing a term used by some physico-chemists (of whom I believe Roscoe is one) and implying an agency which does not produce any effect for some time, and continues its effect for some time after the cause has ceased. I believe that photographic paper is an instance. I must ask Leonard (762/4. Mr. Darwin's son.) whether an interrupted light acts on it in the same manner as on a plant. At present I must still believe in my explanation that it is the contrast between light and darkness which excites a plant. I have forgotten my main object in writing--viz., to say that I believe (and have so stated) that seedlings vary much in their sensitiveness to light; but I did not prove this, for there are many difficulties, whether the time of incipient curvature or the amount of curvature is taken as the criterion. Moreover they vary according to age, and perhaps from vigour of growth, and there seems inherent variability, as Strasburger (whom I quote) found with spores. If the curious anomaly observed by you is due to varying sensitiveness, ought not all the seedlings to bend if the flashes were at longer intervals of time? According to my notion of contrast between light and darkness being the stimulus, I should expect that if flashes were made sufficiently slow it would be a powerful stimulus, and that you would suddenly arrive at a period when the result would SUDDENLY become great. On the other hand, as far as my experience goes, what one expects rarely happens. LETTER 763. TO JULIUS WIESNER. Down, October 4th, 1881. I thank you sincerely for your very kind letter, and for the present of your new work. (763/1. "Das Bewegungsvermogen der Pflanze," 1881. One of us has given some account of Wiesner's book in the presidential address to Section D of the British Association, 1891. Wiesner's divergence from Darwin's views is far-reaching, and includes the main thesis of the "Power of Movement." See "Life and Letters," III., page 336, for an interesting letter to Wiesner.) My son Francis, if he had been at home, would have likewise sent his thanks. I will immediately begin to read your book, and when I have finished it will write again. But I read german so very slowly that your book will take me a considerable time, for I cannot read for more than half an hour each day. I have, also, been working too hard lately, and with very little success, so that I am going to leave home for a time and try to forget science. I quite expect that you will find some gross errors in my work, for you are a very much more skilful and profound experimentalist than I am. Although I always am endeavouring to be cautious and to mistrust myself, yet I know well how apt I am to make blunders. Physiology, both animal and vegetable, is so difficult a subject, that it seems to me to progress chiefly by the elimination or correction of ever-recurring mistakes. I hope that you will not have upset my fundamental notion that various classes of movement result from the modification of a universally present movement of circumnutation. I am very glad that you will again discuss the view of the turgescence of the cells being the cause of the movement of parts. I adopted De Vries' views as seeming to me the most probable, but of late I have felt more doubts on this head. (763/2. See "Power of Movement," page 2. De Vries' work is published in the "Bot. Zeitung," 1879, page 830.) LETTER 764. TO J.D. HOOKER. Glenrhydding House, Patterdale, Penrith, June 15th, 1881. It was real pleasure to me to see once again your well-known handwriting on the outside of your note. I do not know how long you have returned from Italy, but I am very sorry that you are so bothered already with work and visits. I cannot but think that you are too kind and civil to visitors, and too conscientious about your official work. But a man cannot cure his virtues, any more than his vices, after early youth; so you must bear your burthen. It is, however, a great misfortune for science that you have so very little spare time for the "Genera." I can well believe what an awful job the palms must be. Even their size must be very inconvenient. You and Bentham must hate the monocotyledons, for what work the Orchideae must have been, and Gramineae and Cyperaceae will be. I am rather despondent about myself, and my troubles are of an exactly opposite nature to yours, for idleness is downright misery to me, as I find here, as I cannot forget my discomfort for an hour. I have not the heart or strength at my age to begin any investigation lasting years, which is the only thing which I enjoy; and I have no little jobs which I can do. So I must look forward to Down graveyard as the sweetest place on earth. This place is magnificently beautiful, and I enjoy the scenery, though weary of it; and the weather has been very cold and almost always hazy. I am so glad that your tour has answered for Lady Hooker. We return home on the first week of July, and should be truly glad to aid Lady Hooker in any possible manner which she will suggest. I have written to my gardener to send you plants of Oxalis corniculata (and seeds if possible). I should think so common a weed was never asked for before,--and what a poor return for the hundreds of plants which I have received from Kew! I hope that I have not bothered you by writing so long a note, and I did not intend to do so. If Asa Gray has returned with you, please give him my kindest remembrances. LETTER 765. TO J.D. HOOKER. October 22nd, 1881. I am investigating the action of carbonate of ammonia on chlorophyll, which makes me want the plants in my list. (765/1. "The Action of Carbonate of Ammonia on Chlorophyll Bodies." "Linn. Soc. Journ." XIX., page 262, 1882.) I have incidentally observed one point in Euphorbia, which has astonished me--viz. that in the fine fibrous roots of Euphorbia, the alternate rows of cells in their roots must differ physiologically, though not in external appearance, as their contents after the action of carbonate of ammonia differ most conspicuously... Wiesner of Vienna has just published a book vivisecting me in the most courteous, but awful manner, about the "Power of Movement in Plants." (765/2. See Letter 763, note.) Thank heaven, he admits almost all my facts, after re-trying all my experiments; but gives widely different interpretation of the facts. I think he proves me wrong in several cases, but I am convinced that he is utterly erroneous and fanciful in other explanations. No man was ever vivisected in so sweet a manner before, as I am in this book. CHAPTER 2.XII. VIVISECTION AND MISCELLANEOUS SUBJECTS, 1867-1882. 2.XII.I. VIVISECTION, 1875-1882. LETTER 766. TO LORD PLAYFAIR. (766/1. A Bill was introduced to the House of Commons by Messrs. Lyon Playfair, Walpole and Ashley, in the spring of 1875, but was withdrawn on the appointment of a Royal Commission to inquire into the whole question. Some account of the Anti-Vivisection agitation, the introduction of bills, and the appointment of a Royal Commission is given in the "Life and Letters," III., page 201, where the more interesting of Darwin's letters on the question are published.) Down, May 26th, 1875. I hope that you will excuse my troubling you once again. I received some days ago a letter from Prof. Huxley, in Edinburgh, who says with respect to your Bill: "the professors here are all in arms about it, and as the papers have associated my name with the Bill, I shall have to repudiate it publicly, unless something can be done. But what in the world is to be done?" (766/2. The letter is published in full in Mr. L. Huxley's interesting chapter on the vivisection question in his father's "Life," I., page 438.) Dr. Burdon Sanderson is in nearly the same frame of mind about it. The newspapers take different views of the purport of the Bill, but it seems generally supposed that it would prevent demonstrations on animals rendered insensible, and this seems to me a monstrous provision. It would, moreover, probably defeat the end desired; for Dr. B. Sanderson, who demonstrates to his class on animals rendered insensible, told me that some of his students had declared to him that unless he had shown them what he had, they would have experimented on live animals for themselves. Certainly I do not believe that any one could thoroughly understand the action of the heart without having seen it in action. I do not doubt that you wish to aid the progress of Physiology, and at the same time save animals from all useless suffering; and in this case I believe that you could not do a greater service than to warn the Home Secretary with respect to the appointment of Royal Commissioners, that ordinary doctors know little or nothing about Physiology as a science, and are incompetent to judge of its high importance and of the probability of its hereafter conferring great benefits on mankind. LETTER 767. TO LORD PLAYFAIR. Down, May 28th. I must write one line to thank you for your very kind letter, and to say that, after despatching my last note, it suddenly occurred to me that I had been rude in calling one of the provisions of your Bill "monstrous" or "absurd"--I forget which. But when I wrote the expression it was addressed to the bigots who, I believed, had forced you to a compromise. I cannot understand what Dr. B. Sanderson could have been about not to have objected with respect to the clause of not demonstrating on animals rendered insensible. I am extremely sorry that you have had trouble and vexation on the subject. It is a most disagreeable and difficult one. I am not personally concerned, as I never tried an experiment on a living animal, nor am I a physiologist; but I know enough to see how ruinous it would be to stop all progress in so grand a science as Physiology. I commenced the agitation amongst the physiologists for this reason, and because I have long felt very keenly on the question of useless vivisection, and believed, though without any good evidence, that there was not always, even in this country, care enough taken. Pray forgive me this note, so much about myself... LETTER 768. TO G.J. ROMANES. (768/1. Published in "Life of Romanes," page 61, under 1876-77.) Down, June 4th [1876]. Your letter has made me as proud and conceited as ten peacocks. (768/2. This may perhaps refer to Darwin being elected the only honorary member of the Physiological Society, a fact that was announced in a letter from Romanes June 1st, 1876, published in the "Life" of Romanes, page 50. Dr. Sharpey was subsequently elected a second honorary member.) I am inclined to think that writing against the bigots about vivisection is as hopeless as stemming a torrent with a reed. Frank, who has just come here, and who sputters with indignation on the subject, takes an opposite line, and perhaps he is right; anyhow, he had the best of an argument with me on the subject...It seems to me the physiologists are now in the position of a persecuted religious sect, and they must grin and bear the persecution, however cruel and unjust, as well as they can. LETTER 769. TO T. LAUDER BRUNTON. (769/1. In November, 1881, an absolutely groundless charge was brought by the Victoria Street Society for the Protection of Animals from Vivisection against Dr. Ferrier for an infringement of the Vivisection Act. The experiment complained of was the removal of the brain of a monkey and the subsequent testing of the animal's powers of reacting to certain treatment. The fact that the operation had been performed six months before the case came into court would alone have been fatal to the prosecution. Moreover, it was not performed by Dr. Ferrier, but by another observer, who was licensed under the Act to keep the monkey alive after the operation, which was performed under anaesthetics. Thus the prosecution completely broke down, and the case was dismissed. (769/2. From the "British Medical Journal," November 19th, 1881. See also "Times," November 18th, 1881.) The sympathy with Dr. Ferrier in the purely scientific and medical world was very strong, and the British Medical Association undertook the defence. The prosecution did good in one respect, inasmuch as it led to the formation of the Science Defence Association, to which reference is made in some of Mr. Darwin's letters to Sir Lauder Brunton. The Association still exists, and continues to do good work. Part of the following letter was published in the "British Medical Journal," December 3rd, 1881.) Down, November 19th, 1881. I saw in some paper that there would probably be a subscription to pay Dr. Ferrier's legal expenses in the late absurd and wicked prosecution. As I live so retired I might not hear of the subscription, and I should regret beyond measure not to have the pleasure and honour of showing my sympathy [with] and admiration of Dr. Ferrier's researches. I know that you are his friend, as I once met him at your house; so I earnestly beg you to let me hear if there is any means of subscribing, as I should much like to be an early subscriber. I am sure that you will forgive me for troubling you under these circumstances. P.S.--I finished reading a few days ago the several physiological and medical papers which you were so kind as to send me. (769/3. Some of Lauder Brunton's publications.) I was much interested by several of them, especially by that on night-sweating, and almost more by others on digestion. I have seldom been made to realise more vividly the wondrous complexity of our whole system. How any one of us keeps alive for a day is a marvel! LETTER 770. T. LAUDER BRUNTON TO CHARLES DARWIN. 50, Welbeck Street, London, November 21st, 1881. I thank you most sincerely for your kind letter and your offer of assistance to Dr. Ferrier. There is at present no subscription list, as the British Medical Association have taken up the case, and ought to pay the expenses. Should these make such a call upon the funds of the Association as to interfere with its other objects, the whole or part of the expenses will be paid by those who have subscribed to a guarantee fund. To this fund there are already a number of subscribers, whose names are taken by Professor Gerald Yeo, one of the secretaries of the Physiological Society. They have not subscribed a definite sum, but have simply fixed a maximum which they will subscribe, if necessary, on the understanding that only so much as is required shall be asked from each subscriber in proportion to his subscription. It is proposed to send by-and-by a list of the most prominent members of this guarantee fund to the "Times" and other papers, and not only every scientific man, but every member of the medical profession, will rejoice to see your name in the list. Dr. Ferrier has been quite worn out by the worry of this prosecution, or, as it might well be called, persecution, and has gone down to Shanklin for a couple of days. He returns this afternoon, and I have sent on your letter to await his arrival, knowing as I do that it will be to him like cold water to a thirsty soul. LETTER 771. TO T. LAUDER BRUNTON. Down, November 22nd, 1881. Many thanks for your very kind and interesting letter... I write now to beg a favour. I do not in the least know what others have guaranteed in relation to Dr. Ferrier. (771/1. In a letter dated November 27th, 1881, Sir Lauder Brunton wrote in reply to Mr. Darwin's inquiry as to the amount of the subscriptions: "When I ascertain what they intend to give under the new conditions--viz., that the subscriptions are not to be applied to Ferrier's defence, but to the defence of others who may be attacked and to a diffusion of knowledge regarding the nature and purposes of vivisection, I will let you know...") Would twenty guineas be sufficient? If not, will you kindly take the trouble to have my name put down for thirty or forty guineas, as you may think best. If, on the other hand, no one else has guaranteed for as much as twenty guineas, will you put me down for ten or fifteen guineas, though I should like to give twenty best. You can understand that I do not wish to be conspicuous either by too little or too much; so I beg you to be so very kind as to act for me. I have a multitude of letters which I must answer, so excuse haste. LETTER 772. TO T. LAUDER BRUNTON. (772/1. The following letter was written in reply to Sir T. Lauder Brunton's suggestion that Mr. Darwin should be proposed as President of the Science Defence Association.) 4, Bryanston Street, Portman Square, December 17th, 1881. I have been thinking a good deal about the suggestion which you made to me the other day, on the supposition that you could not get some man like the President of the College of Physicians to accept the office. My wife is strongly opposed to my accepting the office, as she feels sure that the anxiety thus caused would tell heavily on my health. But there is a much stronger objection suggested to me by one of my relations--namely, no man ought to allow himself to be placed at the head (though only nominally so) of an associated movement, unless he has the means of judging of the acts performed by the association, after hearing each point discussed. This occurred to me when you spoke to me, and I think that I said something to this effect. Anyhow, I have in several analogous cases acted on this principle. Take, for instance, any preliminary statement which the Association may publish. I might feel grave doubts about the wisdom or justice of some points, and this solely from my not having heard them discussed. I am therefore inclined to think that it would not be right in me to accept the nominal Presidency of your Association, and thus have to act blindly. As far as I can at present see, I fear that I must confine my assistance to subscribing as large a sum to the Association as any member gives. I am sorry to trouble you, but I have thought it best to tell you at once of the doubts which have arisen in my mind. LETTER 773. TO LAUDER BRUNTON. (773/1. Sir T. Lauder Brunton had written (February 12th) to Mr. Darwin explaining that two opinions were held as to the constitution of the proposed Science Defence Association: one that it should consist of a small number of representative men; the other that it should, if possible, embrace every medical practitioner in the country. Sir Lauder Brunton adds: "I should be very greatly obliged if you would kindly say what you think of the two schemes.") Down, February 14th, 1882. I am very much obliged for your information in regard to the Association, about which I feel a great interest. It seems to me highly desirable that the Association should include as many medical and scientific men as possible throughout the whole country, who could illumine those capable of illumination on the necessity of physiological research; but that the Association should be governed by a council of powerful men, not too many in number. Such a council, as representing a large body of medical men, would have more power in the eyes of vote-hunting politicians than a small body representing only themselves. From what I see of country practitioners, I think that their annual subscription ought to be very small. But would it not be possible to add to the rules some such statement as the following one: "That by a donation of... pounds, or of any larger sum, from those who feel a deep interest in the progress of medical science, the donor shall become a life member." I, for one, would gladly subscribe 50 or 100 pounds. If such a plan were approved by the leading medical men of London, two or three thousand pounds might at once be collected; and if any such sum could be announced as already subscribed, when the program of the Association is put forth, it would have, as I believe, a considerable influence on the country, and would attract the attention of country practitioners. The Anti-Corn Law League owed much of its enormous power to several wealthy men laying down 1,000 pounds; for the subscription of a good sum of money is the best proof of earnest conviction. You asked for my opinion on the above points, and I have given it freely, though well aware that from living so retired a life my judgment cannot be worth much. Have you read Mr. Gurney's articles in the "Fortnightly" and "Cornhill?" (773/2. "Fortnightly Review," XXX., page 778; "Cornhill Magazine," XLV., page 191. The articles are by the late Edmund Gurney, author of "The power of Sound," 1880.) They seem to me very clever, though obscurely written; and I agree with almost everything he says, except with some passages which appear to imply that no experiments should be tried unless some immediate good can be predicted, and this is a gigantic mistake contradicted by the whole history of science. P.S.--That is a curious fact about babies. I remember hearing on good authority that very young babies when moved are apt to clutch hold of anything, and I thought of your explanation; but your case during sleep is a much more interesting one. Very many thanks for the book, which I much wanted to see; it shall be sent back to-day, as from you, to the Society. 2.XII.II. MISCELLANEOUS SUBJECTS, 1867-1882. LETTER 774. TO CANON FARRAR. (774/1. The lecture which forms the subject of this letter was one delivered by Canon Farrar at the Royal Institution, "On Some Defects in Public School Education.") Down, March 5th, 1867. I am very much obliged for your kind present of your lecture. We have read it aloud with the greatest interest, and I agree to every word. I admire your candour and wonderful freedom from prejudice; for I feel an inward conviction that if I had been a great classical scholar I should never have been able to have judged fairly on the subject. As it is, I am one of the root and branch men, and would leave classics to be learnt by those alone who have sufficient zeal and the high taste requisite for their appreciation. You have indeed done a great public service in speaking out so boldly. Scientific men might rail forever, and it would only be said that they railed at what they did not understand. I was at school at Shrewsbury under a great scholar, Dr. Butler; I learnt absolutely nothing, except by amusing myself by reading and experimenting in chemistry. Dr. Butler somehow found this out, and publicly sneered at me before the whole school for such gross waste of time; I remember he called me a Pococurante (774/2. Told in "Life and Letters," I., page 35.), which, not understanding, I thought was a dreadful name. I wish you had shown in your lecture how science could practically be taught in a great school; I have often heard it objected that this could not be done, and I never knew what to say in answer. I heartily hope that you may live to see your zeal and labour produce good fruit. LETTER 775. TO HERBERT SPENCER. Down, December 9th [1867]. I thank you very sincerely for your kind present of your "First Principles." (775/1. "This must have been the second edition." (Note by Mr. Spencer.)) I earnestly hope that before long I may have strength to study the work as it ought to be studied, for I am certain to find or re-find much that is deeply interesting. In many parts of your "Principles of Biology" I was fairly astonished at the prodigality of your original views. (775/2. See "Life and Letters," III., pages 55, 56.) Most of the chapters furnished suggestions for whole volumes of future researches. As I have heard that you have changed your residence, I am forced to address this to Messrs. Williams & Norgate; and for the same reason I gave some time ago the same address to Mr. Murray for a copy of my book on variation, etc., which is now finished, but delayed by the index-maker. LETTER 776. TO T.H. HUXLEY. (776/1. This letter refers to a movement set on foot at a meeting held at the Freemasons' Tavern, on November 16th, 1872, of which an account is given in the "Times" of November 23rd, 1872, at which Mark Pattison, Mr. Henry Sidgwick, Sir Benjamin Brodie, Professors Rolleston, Seeley, Huxley, etc., were present. The "Times" says that the meeting was held "by members of the Universities and others interested in the promotion of mature study and scientific research in England." One of the headings of the "Program of Discussion" was "The Abolition of Prize Fellowships.") Sevenoaks, October 22nd [1872]. I have been glad to sign and forward the paper, for I have very long thought it a sin that the immense funds of the Universities should be wasted in Fellowships, except a few for paying for education. But when I was at Cambridge it would have been an unjustifiable sneer to have spoken of the place as one for education, always excepting the men who went in for honours. You speak of another resolution "in the interest of the anti-letter-writing association"--but alas, this never arrived! I should like a society formed so that every one might receive pleasant letters and never answer them. We return home on Saturday, after three weeks of the most astounding dullness, doing nothing and thinking of nothing. I hope my Brain likes it--as for myself, it is dreadful doing nothing. (776/2. Darwin returned to Down from Sevenoaks on Saturday, October 26th, 1872, which fixes the date of the letter.) LETTER 777. TO LADY DERBY. Down, Saturday [1874?]. If you had called here after I had read the article you would have found a much perplexed man. (777/1. Probably Sir W. Crookes' "Researches in the Phenomena of Spiritualism" (reprinted from the "Quarterly Journal of Science"), London, 1874. Other papers by Crookes are in the "Proceedings of the Society for Psychical Research.") I cannot disbelieve Mr. Crooke's statement, nor can I believe in his result. It has removed some of my difficulty that the supposed power is not an anomaly, but is common in a lesser degree to various persons. It is also a consolation to reflect that gravity acts at any distance, in some wholly unknown manner, and so may nerve-force. Nothing is so difficult to decide as where to draw a just line between scepticism and credulity. It was a very long time before scientific men would believe in the fall of aerolites; and this was chiefly owing to so much bad evidence, as in the present case, being mixed up with the good. All sorts of objects were said to have been seen falling from the sky. I very much hope that a number of men, such as Professor Stokes, will be induced to witness Mr. Crooke's experiments. (778/1. The two following extracts may be given in further illustration of Darwin's guiding principle in weighing evidence. He wrote to Robert Chambers, April 30th, 1861: "Thanks also for extract out of newspaper about rooks and crows; I wish I dared trust it. I see in cutting the pages [of Chambers' book, "Ice and Water"]...that you fulminate against the scepticism of scientific men. You would not fulminate quite so much if you had had so many wild-goose chases after facts stated by men not trained to scientific accuracy. I often vow to myself that I will utterly disregard every statement made by any one who has not shown the world he can observe accurately." In a letter to Dr. Dohrn, of Naples, January 4th, 1870, Darwin wrote: "Forgive me for suggesting one caution; as Demosthenes said, 'Action, action, action,' was the soul of eloquence, so is caution almost the soul of science.") LETTER 778. TO J. BURDON SANDERSON. Down, July 16th, 1875. Some little time ago Mr. Simon (778/1. Now Sir John Simon) sent me the last Report, and your statements about contagion deeply interested me. By the way, if you see Mr. Simon, and can remember it, will you thank him for me; I was so busy at the time that I did not write. Having been in correspondence with Paget lately on another subject, I mentioned to him an analogy which has struck me much, now that we know that sheep-pox is fungoid; and this analogy pleased him. It is that of fairy rings, which are believed to spread from a centre, and when they intersect the intersecting portion dies out, as the mycelium cannot grow where it has grown during previous years. So, again, I have never seen a ring within a ring; this seems to me a parallel case to a man commonly having the smallpox only once. I imagine that in both cases the mycelium must consume all the matter on which it can subsist. LETTER 779. TO A. GAPITCHE. (779/1. The following letter was written to the author (under the pseudonym of Gapitche) of a pamphlet entitled "Quelques mots sur l'Eternite du Corps Humaine" (Nice, 1880). Mr. Gapitche's idea was that man might, by perfect adaptation to his surroundings, indefinitely prolong the duration of life. We owe Mr. Darwin's letter to the kindness of Herr Vetter, editor of the well-known journal "Kosmos.") Down, February 24th, 1880. I suppose that no one can prove that death is inevitable, but the evidence in favour of this belief is overwhelmingly strong from the evidence of all other living creatures. I do not believe that it is by any means invariably true that the higher organisms always live longer than the lower ones. Elephants, parrots, ravens, tortoises, and some fish live longer than man. As evolution depends on a long succession of generations, which implies death, it seems to me in the highest degree improbable that man should cease to follow the general law of evolution, and this would follow if he were to be immortal. This is all that I can say. LETTER 780. TO J. POPPER. (780/1. Mr. Popper had written about a proposed flying machine in which birds were to take a part.) Down, February 15th, 1881. I am sorry to say that I cannot give you the least aid, as I have never attended to any mechanical subjects. I should doubt whether it would be possible to train birds to fly in a certain direction in a body, though I am aware that they have been taught some tricks. Their mental powers are probably much below those of mammals. It is said, and I suppose truly, that an eagle will carry a lamb. This shows that a bird may have great power for a short distance. I cannot remember your essay with sufficient distinctness to make any remarks on it. When a man is old and works hard, one subject drives another out of his head. LETTER 781. TO T.H. HUXLEY. Worthing, September 9th, 1881. (781/1. Mr. Anthony Rich left his house at Worthing as a legacy to Mr. Huxley. See Huxley's "Life and Letters," II., pages 286, 287.) We have been paying Mr. Rich a little visit, and he has often spoken of you, and I think he enjoyed much your and Mrs. Huxley's visit here. But my object in writing now is to tell you something, which I am very doubtful whether it is worth while for you to hear, because it is uncertain. My brother Erasmus has left me half his fortune, which is very considerable. Therefore, I thought myself bound to tell Mr. Rich of this, stating the large amount, as far as the executors as yet know it roughly. I then added that my wife and self thought that, under these new circumstances, he was most fully justified in altering his will and leaving his property in some other way. I begged him to take a week to consider what I had told him, and then by letter to inform me of the result. But he would not, however, hardly allow me to finish what I had to say, and expressed a firm determination not to alter his will, adding that I had five sons to provide for. After a short pause he implied (but unfortunately he here became very confused and forgot a word, which on subsequent reflection I think was probably "reversionary")--he implied that there was a chance, whether good or bad I know not, of his becoming possessed of some other property, and he finished by saying distinctly, "I will bequeath this to Huxley." What the amount may be (I fear not large), and what the chance may be, God only knows; and one cannot cross-examine a man about his will. He did not bind me to secrecy, so I think I am justified in telling you what passed, but whether it is wise on my part to send so vague a story, I am not at all sure; but as a general rule it is best to tell everything. As I know that you hate writing letters, do not trouble yourself to answer this. P.S.--On further reflection I should like to hear that you receive this note safely. I have used up all my black-edged paper. LETTER 782. TO ANTHONY RICH. Down, February 4th, 1882. It is always a pleasure to me to receive a letter from you. I am very sorry to hear that you have been more troubled than usual with your old complaint. Any one who looked at you would think that you had passed through life with few evils, and yet you have had an unusual amount of suffering. As a turnkey remarked in one of Dickens' novels, "Life is a rum thing." (782/1. This we take to be an incorrect version of Mr. Roker's remark (in reference to Tom Martin, the Butcher), "What a rum thing Time is, ain't it, Neddy?" ("Pickwick," Chapter XLII.). A careful student finds that women are also apostrophised as "rum": see the remarks of the dirty-faced man ("Pickwick," Chapter XIV.).) As for myself, I have been better than usual until about a fortnight ago, when I had a cough, and this pulled me down and made me miserable to a strange degree; but my dear old wife insisted on my taking quinine, and, though I have very little faith in medicine, this, I think, has done me much good. Well, we are both so old that we must expect some troubles: I shall be seventy-three on Feb. 12th. I have been glad to hear about the pine-leaves, and you are the first man who has confirmed my account that they are drawn in by the base, with a very few exceptions. (782/2. "The Formation of Vegetable Mould through the Action of Worms," 1881, page 71.) With respect to your Wandsworth case, I think that if I had heard of it before publishing, I would have said nothing about the ledges (782/3. "Ledges of Earth on Steep Hill-sides" (ibid., page 278).); for the Grisedale case (782/4. "The steep, grass-covered sides of a mountainous valley in Westmorland, called Grisedale, were marked in many places with innumerable, almost horizontal, little ledges...Their formation was in no way connected with the action of worms (and their absence is an inexplicable fact)...(ibid., page 282.), mentioned in my book and observed whilst I was correcting the proof-sheets, made me feel rather doubtful. Yet the Corniche case (782/5. Ibid., page 281.) shows that worms at least aid in making the ledges. Nevertheless, I wish I had said nothing about the confounded ledges. The success of this worm book has been almost laughable. I have, however, been plagued with an endless stream of letters on the subject; most of them very foolish and enthusiastic, but some containing good facts, which I have used in correcting yesterday the "sixth Thousand." Your friend George's work about the viscous state of the earth and tides and the moon has lately been attracting much attention (782/6. Published in the "Philosophical Transactions of the Royal Society," 1879, 1880, 1881.), and all the great judges think highly of the work. He intends to try for the Plumian Professorship of Mathematics and Natural Philosophy at Cambridge, which is a good and honourable post of about 800 pounds a year. I think that he will get it (782/7. He was elected Plumian Professor of Astronomy and Experimental Philosophy in 1883.) when Challis is dead, and he is very near his end. He has all the great men--Sir W. Thomson, Adams, Stokes, etc.--on his side. He has lately been chief examiner for the Mathematical Tripos, which was tremendous work; and the day before yesterday he started for Southampton for a five-weeks' tour to Jamaica for complete rest, to see the Blue Mountains, and escape the rigour of the early spring. I believe that George will some day be a great scientific swell. The War Office has just offered Leonard a post in the Government Survey at Southampton, and very civilly told him to go down and inspect the place, and accept or not as he liked. So he went down, but has decided that it would not be worth his while to accept, as it would entail his giving up his expedition (on which he had been ordered) to Queensland, in Australia, to observe the Transit of Venus. (782/8. Major Leonard Darwin, late R.E., served in several scientific expeditions, including the Transits of Venus of 1874 and 1882.) Dear old William at Southampton has not been very well, but is now better. He has had too much work--a willing horse is always overworked--and all the arrangements for receiving the British Association there this summer have been thrown on his shoulders. But, good Heavens! what a deal I have written about my sons. I have had some hard work this autumn with the microscope; but this is over, and I have only to write out the papers for the Linnean Society. (782/9. i. "The Action of Carbonate of Ammonia on the Roots of Certain plants." [Read March 16th, 1882.] "Journ. Linn. Soc." Volume XIX., 1882, page 239. ii. "The Action of Carbonate of Ammonia on Chlorophyll-bodies." [Read March 6th, 1882.] Ibid., page 262.) We have had a good many visitors; but none who would have interested you, except perhaps Mrs. Ritchie, the daughter of Thackeray, who is a most amusing and pleasant person. I have not seen Huxley for some time, but my wife heard this morning from Mrs. Huxley, who wrote from her bed, with a bad account of herself and several of her children; but none, I hope, are at all dangerously ill. Farewell, my kind, good friend. Many thanks about the picture, which if I survive you, and this I do not expect, shall be hung in my study as a perpetual memento of you. (782/10. The concluding chapter of the "Life and Letters" gives some account of the gradual failure in health which was perceptible in the last year of Mr. Darwin's life. He died on April 19th, 1882, in his 74th year.) THE END. INDEX. INDEX. [The German a-, o-, u-diaeresis are treated as a, o, u, not as ae, oe, ue.] Aberrant genera, Darwin's work on. Abich, on Vesuvius. Abinger, excavations of Roman villa at. -plants from. Abinger Hall, Darwin visits. -Lord Farrer's recollections of Darwin at. Abiogenesis, Huxley's address on Biogenesis and. Abortion, Romanes on. Abrolhos, plants from the. Abromia. Abrus precatorius, dispersal of seeds. Abstract, Darwin's dislike of writing papers in. Abstract, the name applied by Darwin to the "Origin." Abutilon, F. Muller's experiments on. Abyssinia, flora of. "Academy," Darwin's opinion of the. Acanthaceae. Acceleration of development, Cope and Hyatt on retardation and. -reference in the "Origin" to. Accumulation, of deposits in relation to earth-movements. -of specific differences. -of sterility. -of varieties. Accuracy, difficult to attain. -the soul of Natural History. Aceras, fertilisation of. -monstrous flower. Acineta, Darwin unable to fertilise. Aconitum, peloria and reversion. Acropera, atrophy of ovules. -Darwin's mistake over. -fertilisation of. -relation to Gongora. -J. Scott's work on. Acropera Loddigesii, abnormal structure of ovary. -Darwin's account of flower. -artificial fertilisation. -relation to A. luteola. -J. Scott's observations. -two sexual conditions of. -A. luteola, Darwin's observations on. -fertilisation of. -flowers of. -structure of ovary. Adaptation, Darwin's difficulty in understanding. -hybrids and. -not the governing law in Geographical Distribution. -more clearly seen in animals than plants. -Natural Selection and. -in orchids. -resemblances due to. -in Woodpecker. Adenanthera pavonina, seed-dispersal by Parrots. Adenocarpus, a Mediterranean genus in the Cameroons. Adlumia. Adoxa, difference in flowers of same plant. Aecidium elatinum, Witches'-Broom fungus. Aegialitis Sanctae-helenae. Aegilops triticoides, hybrids. Affaiblissement, A. St. Hilaire on. Africa, connection with Ceylon. -connection with India. -continent of Lemuria and. -considered by Murchison oldest continent. -plants of equatorial mountains of. Africa (East,) coral reefs on coast. Africa (South), plants of. -relation of floras of Western Europe to. Africa (West), botanical relation to Java. Agassiz, Alex., "Three Cruises of the 'Blake.'" -his belief in evolution the result of F. Muller's writings. -account of Florida Coral-reefs. -letters to. -visits Down. Agassiz, Louis Jean Rodolphe (1807-73): entered a college at Bienne at the age of ten, and from 1822 to 1824 he was a student at the Academy of Lausanne. Agassiz afterwards spent some years as a student in the Universities of Zurich, Heidelberg, and Munich, where he gained a reputation as a skilled fencer. It was at Heidelberg that his studies took a definite turn towards Natural History. He took a Ph.D. degree at Erlangen in 1829. Agassiz published his first paper in "Isis" in 1828, and for many years devoted himself chiefly to Ichthyology. During a visit to Paris he became acquainted with Cuvier and Alexander von Humboldt; in 1833, through the liberality of the latter, he began the publication of his "Recherches sur les Poissons Fossiles," and in 1840 he completed his "Etudes sur les Glaciers." In 1846 Agassiz went to Boston, where he lectured in the Lowell Institute, and in the following year became Professor of Geology and Zoology at Cambridge. During the last twenty-seven years of his life Agassiz lived in America, and exerted a great influence on the study of Natural History in the United States. In 1836 he received the Wollaston Medal of the Geological Society of London, and in 1861 he was selected for the Copley Medal of the Royal Society. In 1873 Agassiz dictated an article to Mrs. Agassiz on "Evolution and Permanence of Type," in which he repeated his strong conviction against the views embodied in the "Origin of Species." See "Life, Letters, and Works of Louis Agassiz," by Jules Marcou, 2 volumes, New York, 1896; "Louis Agassiz: his Life and Correspondence," edited by Elizabeth Cary Agassiz, 2 volumes, London, 1885; "Smithsonian Report," 1873, page 198. -attack on "Origin." -Darwin's criticism of book on Brazil. -Darwin's opinion of. -views on creation of species. -on geographical distribution. -"Methods of Study" by. -misstatement of Darwin's views. -Walsh on. -"Etudes sur les Glaciers." -Darwin on glacier work of. -on glaciers in Ceara Mts. -glacier-ice-lake theory of Parallel Roads of Glen Roy. -on glacier moraines. -on rock-cavities formed by glacier-cascades. -on Darwin's theory. -on Geology of the Amazons. -doubts recent upheaval of Patagonia. -mentioned. Age of the world. Aggressive plants, introduction of. Agricultural Society, experiments on potatoes. Airy, H. letter to. Albemarle Island, Darwin's collection of plants from. -volcanoes of. Aldrovanda. Alerse ("Alerce"), occurrence in Chiloe. Algae, movement of male-cells to female organ. Alisma, F. Muller's observations on. -submerged flowers of. Alisma macrophylla, circumnutation of. Allbutt, Prof. Clifford, on sperm-cells. Allen, Grant, review by Romanes of his "Physiological Aesthetics." Allen, J.A., on colours of birds. -on mammals and birds of Florida. Allogamy, use of term. Almond, seedling peaches resembling. Alopecurus pratensis, fertilisation of. Alpine floras, Arctic and. -of Azores, Canaries and Madeira. -absence of, in southern islands. -Ball on origin of flora. -Darwin's work on. -of United States. -existence prior to Glacial period. -Ice-action in New Zealand, and. -Ball on origin of. Alpine insects. Alpine plants. -change due to transplanting. -slight change in isolated forms. -as evidence of continental land at close of Glacial period. Alps, Australian. -Murchison on structure of. -submergence. -Tyndall's book on. Alternate generations, in Hydrozoa. Amazonia, Insects of. Amazons, L. Agassiz on glacial phenomena in valley of. -L. Agassiz on geology of. -Bates on lepidoptera of. -sedimentation off mouth of. Amber, extinct plants preserved in. Amblyopsis, a blind cave-fish, effect of conditions on. Ameghino, Prof., discovery of Neomylodon Listai. America (North), are European birds blown to? -Falconer on elephants. -fauna and flora of Japan and. -flora of. -mammalian fauna. -introduction of European weeds. -subsidence during Glacial period. -western European plants and flora of. -contrast during Tertiary period between South and. -former greater distinction between fauna of South and. -glaciation of South and. -Rogers on coal-fields. America (South), Bollaert's "Antiquities" of. -Araucarian fossil wood from. -Carabi of. -elevation of coast. -fauna of. -floras of Australia and. -geology of. -Darwin's "Geological Observations" on. -deposition of sediment on coast. -European plants in. -frequency of earthquakes. -D. Forbes on geology of. -W. Jameson on geology of. -D'Orbigny on. -volcanic eruptions. -Wallace opposed to continent uniting New Zealand, Australia and. American War. Ammonia, Darwin's work on effect on roots of carbonate of. Ammonites, degeneration of. -reversion. -of S. America. Amsinckia. Amsinckia spectabilis, dimorphism of. Anacamptis (=Orchis pyramidalis), fertilisation of. Anacharis (=Elodea Canadensis), spread of. Analogy, difference between homology and. Anamorphism, Huxley on. Anatifera, illustrating difficulty in nomenclature. Anatomy of Vertebrata, Owen's attack on Darwin and Lyell in. "Ancient Sea Margins," by R. Chambers. Anderson-Henry, Isaac (1799?-1884): of Edinburgh, was educated as a lawyer, but devoted himself to horticulture, more particularly to experimental work on grafting and hybridisation. As President of the Botanical Society of Edinburgh he delivered two addresses on "Hybridisation or Crossing of Plants," of which a full abstract was published in the "Gardeners' Chronicle," April 13th, 1867, page 379, and December 21st, 1867, page 1296. See obit. notice in "Gardeners' Chronicle," September 27th, 1884, page 400. -letter to. Andes, Darwin on geology of. -high-road for European plants. -comparatively recent origin. Anemophilous plants, Delpino's work on. Angiosperms, origin of. Angraecum sesquipedale, Duke of Argyll on. Animal Intelligence, Romanes on. Animals, difference between plants and. -resemblance to plants. Annuals, adapted to short seasons. -Hildebrand on percentages of. Anoplotherium, occurrence in Eocene of S. America. Ansted, David Thomas, F.R.S. (1814-80): Fellow of Jesus College, Cambridge, Professor of Geology at King's College, London, author of several papers and books on geological subjects (see "Quart. Journ. Geol. Soc." Volume XXXVII., page 43.) -letter to. Antarctic continent, Darwin on existence of Tertiary. -hypothetical. "Antarctic Flora," Sir J.D. Hooker's. Antarctic floras. -Darwin at work on. Antarctic islands, plants of. Antarctic Land. "Anti-Jacobin," quiz on Erasmus Darwin in. "Antiquity of Man," Sir Charles Lyell's. -cautious views on species. -Darwin's criticism of. -Extract on Natural Selection from. -Falconer on. -Owen's criticism on. Antirrhinum, peloric flowers. Ants, account in "Origin" of Slave-. -Forel's work on. -Moggridge on Harvesting-. -F. Muller's observations on neuter. -storing leaves for plant-culture. Apathus, living in nests of Bombus. Apes, comparison as regards advance in intellect between man and. -ears of anthropoid. Aphides, absence of wings in viviparous. Aphis, Huxley on. Apostasia, morphology of flowers. Appalachian chain, Rogers on cleavage of. Apteryx, Owen on. -wings of. Aquilegia, Hooker and Thomson on. -variation in. -peloria and reversion. Arachis hypogaea, Darwin on. Arachnidae. Araucaria, abundant in Secondary period. Araucarian wood, fossil in S. America. Arca, Morse on. Archaeopteryx. Archer-Hind, R.D., translation of passage from Plato by. Archetype, Owen's book on. -Owen's term. d'Archiac's "Histoire des Progres de la Geologie." -candidate for Royal Society Foreign list. Arctic animals, protective colours. Arctic climate, cause of present. Arctic expeditions, Darwin on. Arctic floras. -relation between Alpine and. -relation between Antarctic and. -Hooker's Essay on. -Darwin's admiration of Hooker's Essay. -migration of. Arctic regions, few plants common to Europe and N. America not ranging to. -range of plants. -northern limit of vegetation formerly lower. -ice piled up in. -previous existence of plants in. Arenaria verna, range. Argus pheasant, colour. -unadorned head. Argyll, Duke of, attack on Romanes in "Nature." -rejoinder by Romanes in "Nature." -Hooker on. -letter to. -"Reign of Law" by. Aristolochia, fertilisation of. Aristotle, reference to. Ark, Fitz-Roy on extinction of Mastodon owing to construction of. Armadillo. Army, measurement of soldiers of U.S.A. Artemia, Schmankewitsch's experiments on. Ascension Island, plants of. -earth-movements. -volcanic rocks. Ascidians, budding of. Asclepiadeae, fertilisation of. Ash, comparison of peat and coal. Asher, Dr., sends Russian wheat to Darwin. Ashley. Ashley Heath, Mackintosh on boulders of. Askenasy, E., on Darwinism. Aspicarpa. Ass, hybrids between mare and. Asterias. Astragalus hypoglottis, range of. Astronomical causes, crust-movements due to. Asturian plants in Ireland. Atavism, use of term by Duchesne. -Kollmann on. Athenaeum Club, Huxley's election. "Athenaeum," correspondence on Darwin's statements on rate of increase of elephants. -Darwin's opinion of. -abuse of Darwin. Atlantic islands, peculiar genera and their origin. Atlantis, America and. -Canary I. and. -Darwin's disbelief in. -Heer's map. -Wollaston's. Atolls, Darwin's wish for investigation by boring of coral. -Darwin on Murray's theory. -Darwin's work on. Atomogenesis, term suggested as substitute for pangenesis. Atriplex, buried seeds found in sandpit near Melrose. Attica, Gaudry on fossil animals. Auckland Island, flora. Audubon, J.J., on antics of birds during courtship. -"Ornithological Biography." Aurelia, Romanes on. Auricula, dimorphism of. -experiments on. Austen, Godwin, on changes of level on English coast. Australia, caves of. -character of fauna. -flora of. -Hooker on flora. -relation of flora to S. America. -relation of flora to S. Africa. -European plants in. -local plants in S.W. -naturalised plants. -plants on mountains. -fossil plants. -dichogamy of trees in. -as illustrating rate and progress of evolution. -Mastodon from. -products of, compared with those of Asia. -submergence. Australian savages and Natural Selection. Australian species, occurrence in Malay Archipelago and Philippines. Autobiographical recollections, Charles Darwin's. Autobiography, extract from Darwin's. Autogamy, Kerner's term. Automatism, Huxley's Essay. Avebury, Lord. -address at British Association meeting at York (1881). -on the Finns and Kjokken moddings. -letters to. -on the "Origin." -"Prehistoric Times." -on the Progress of Science. -on Seedlings. -story of Darwin told by. -Darwin regrets his entrance into politics. -on Ramsay's lake-theory. Averrhoa, Darwin's work on. Axell, Severin, book on fertilisation of plants. Axon, W.E., letter from Darwin to Mrs. E. Talbot published by. Aye Aye, Owen on the. Azara. Azores, organic relation with America. -birds. -European birds as chance wanderers to. -erratic blocks. -flora. -European plants in. -Miocene beds in. -relation to Madeira and Canaries. -Watson on the. -Orchids from. -mentioned. Babies, habit of clutching objects. Babington, Prof. Charles C., at the British Association (Manchester, 1861). -"British Flora." -Darwin sends seeds of Atriplex to. Baden-Powell, Prof. Baer. Bagehot, W., article in "Fortnightly Review" on Physics and Politics. Bahia Blanca, collection of plants from. Bailey, on Heterocentron roseum. Baillon, on pollen-tubes of Helianthemum. Baker's Flora of the Mauritius and Seychelles. Balancement, G. St. Hilaire's law of. Balanidae, Darwin's work on. Balanus, questions of nomenclature. Balfour, F.M. (1851-82): Professor of Animal Morphology at Cambridge. He was born 1851, and was killed, with his guide, on the Aiguille Blanche, near Courmayeur, in July 1882. (See "Life and Letters," III., page 250.) -letter to. -mentioned. Ball, J., on origin of Alpine flora. Ball, P., "The effects of Use and Disuse." Balsaminaceae, genera of. Banks' Cove, volcano of. Barber, C., on graft-hybrids of sugar-cane. Barber, Mrs., on Papilio nireus. Barberry, abundance in N. America. -dispersal of seeds by birds. -Lord Farrer and H. Muller on floral mechanism. -movement of stamens. Barbs, see Pigeons. Bardfield Oxlip (Primula elatior). Barnacles, Darwin's work on. -metamorphosis in. -F. Muller on. -nomenclature. -of Secondary Period. -advance in. -complemental males compared with plants. Barneoud, on irregular flowers. "Baronne Prevost," Rivers on the rose. Barrande, Joachim (died 1883): devoted himself to the investigation of the Palaeozoic fossils of Bohemia, his adopted country. His greatest work was the "Systeme Silurien de la Boheme," of which twenty-two volumes were published before his death. He was awarded the Wollaston Medal of the Geological Society in 1855. Barrande propounded the doctrine of "colonies." He found that in the Silurian strata of Bohemia, containing a normal succession of fossils, exceptional bands occurred which yielded fossils characteristic of a higher zone. He named these bands "colonies," and explained their occurrence by supposing that the later fauna represented in these "precursory bands" had already appeared in a neighbouring region, and that by some means communication was opened at intervals between this region and that in which the normal Silurian series was being deposited. This apparent intercalation of younger among older zones has now been accounted for by infoldings and faulting of the strata. See J.E. Marr, "On the Pre- Devonian Rocks of Bohemia," "Quart. Journ. Geol. Soc." Volume XXXVI., page 591 (1880); also "Defense des Colonies," by J. Barrande (Prag, 1861), and Geikie's "Text-book of Geology" (1893), page 773. -candidature for Royal medal. -candidate for Royal Society foreign list. -work on Colonies. -Lyell on work of. Barriers to plant distribution in America. Barrow, on Emberiza longicauda. -"Travels in S. Africa." Barrow, Sir J., connection with naval expeditions. Barrow, germination of seeds from a. Bartlett, Abraham Dee (1812-97): was resident superintendent of the Zoological Society's Gardens in Regent's Park from 1859 to 1897. He communicated several papers to the Zoological Society. His knowledge was always at the service of Mr. Darwin, who had a sincere respect for him. -letters to. Barton, on trees of N. America. Basalt, association with granite. -separation of trachyte and. Basques, H. Christy on the. -Hooker on Finns and. Bastian, "The Beginnings of Life." Bat, natural selection and increase in size of wings. Bates, Henry Walter (1825-92): was born at Leicester, and after an apprenticeship in a hosiery business he became a clerk in Allsopp's brewery. He did not remain long in this uncongenial position, for in 1848 he embarked for Para with Mr. Wallace, whose acquaintance he had made at Leicester some years previously. Mr. Wallace left Brazil after four years' sojourn, and Bates remained for seven more years. He suffered much ill- health and privation, but in spite of adverse circumstances he worked unceasingly: witness the fact that his collection of insects numbered 14,000 specimens. He became Assistant Secretary to the Royal Geographical Society in 1864, a post which he filled up to the time of his death in 1892. In Mr. Clodd's interesting memoir prefixed to his edition of the "Naturalist on the Amazons," 1892, the editor pays a warm and well-weighed tribute to Mr. Bates's honourable and lovable personal character. See also "Life and Letters," II., page 380. -"A Naturalist on the Amazons." -Darwin's opinion of his work. -on insect fauna of Amazon Valley. -on lepidoptera of Amazons. -letter from Hooker to. -letters to. -letter to Hooker from. -Darwin reviews paper by. -on flower of Monochaetum. -on insects of Chili. -supplies Darwin with facts for sexual selection. Bateson, Miss A., on cross fertilisation in inconspicuous flowers. Bateson, W., on breeding lepidoptera in confinement. -Mendel's "Principles of Heredity." Batrachians, Kollmann on rudimentary digits. Bauer, F., drawings by. Bauhinia, sleep-movements of leaves. Beaches, S. American raised. "Beagle" (H.M.S.), circumstance of Darwin joining. -Darwin's views on species when on. -FitzRoy and voyage of. -return of. -voyage. Beans, holes bitten by bees in flowers. -extra-floral nectaries of. Bear, comparison with whale. -modification of. Beaton, Donald (1802-63): Biographical notices in the "Journal of Horticulture" and the "Cottage Gardener," XIII., page 153, and "Journ. Hort." 1863, pages 349 and 415, are referred to in Britten & Boulger's "Biographical Index of Botanists," 1893. Dr. Masters tells us that Beaton had a "first-rate reputation as a practical gardener, and was esteemed for his shrewdness and humour." -Darwin on work of. -on Pelargonium. Beatson, on land birds in S. Helena. Beaufort. Beaufort, Captain, asks Darwin for information as to collecting. Beaumont, Elie de (1798-1874): was a pupil in the Ecole Polytechnique and afterwards in the Ecole des Mines. In 1820 he accompanied M. Brochant de Villiers to England in order to study the principles of geological mapping, and to report on the English mines and metallurgical establishments. For several years M. de Beaumont was actively engaged in the preparation of the geological map of France, which was begun in 1825, and in 1835 he succeeded M. B. de Villiers in the Chair of Geology at the Ecole des Mines. In 1853 he was elected Perpetual Secretary of the French Academy, and in 1861 he became Vice-President of the Conseil General des Mines and a Grand Officer of the Legion of Honour. Elie de Beaumont is best known among geologists as the author of the "Systemes des Montagnes" and other publications, in which he put forward his theories on the origin of mountain ranges and on kindred subjects. ("Quart. Journ. Geol. Soc." Volume XXXI.; "Proc." page xliii, 1875.) -on lines of elevation. -on elevation in Cordilleras. -elevation-crater theory. -Darwin's disbelief in views and work of. -on lava and dykes. -Lyell's refutation of his theory. -measurement of natural inclination of lava-streams. Beauty, criticism by J. Morley of Darwin's phraseology in regard to. -discussion on. -lepidoptera and display of. -Wallace on. -Darwin's discussion on origin. -in female animals. -in plumage of male and female birds. -of seeds and fruits. -Shaw on. -standards of. Bedford, flint implements found near. Beech, in Chonos I. -in T. del Fuego and Chili. -Miquel on distribution. Bee-Ophrys (Ophrys apifera), see Bee-Orchis. Bee-Orchis, Darwin's experiments on crossing. -fertilisation. -self-fertilisation. -intermediate forms between Ophrys arachnites and. Bees, combs. -Haughton on cells of. -and instinct. -referred to in "Descent of Man." -New Zealand clover and. -acquisition of power of building cells. -Darwin's observations on. -agents in fertilisation of papilionaceous flowers. -as pollen collectors. -difference between sexes. -H. Muller on. -and parthenogenesis. -regular lines of flight at Down. Beet, graft-hybrids. Beete-Jukes, alluded to in De la Beche's presidential address. Beetles, bivalves distributed by. -Forel's work on. -nest-inhabiting. -stag-. -stridulating organs. "Befruchtung der Blumen," H. Muller's, the outcome of Darwin's "Fertilisation of Orchids." Begonia, monstrous flowers. -B. frigida, Hooker on. Begoniaceae, genera of. Behring Straits, spreading of plants from. Belize, coral reefs near. Bell, on Owen's "Edinburgh Review" article. Bell, Sir C., "Anatomy of Expression." Belt, T., on conspicuously coloured animals distasteful to birds. -letter to. -"The Naturalist in Nicaragua." Ben Nevis, Ice-barrier under. Benson, Miss, on Chalazogamy in Amentiferae. Bentham, George (1800-83): son of Sir Samuel Bentham, and nephew of Jeremy, the celebrated authority on jurisprudence. Sir Samuel Bentham was at first in the Russian service, and afterwards in that of his own country, where he attained the rank of Inspector-General of Naval Works. George Bentham was attracted to botany during a "caravan tour" through France in 1816, when he set himself to work out the names of flowers with De Candolle's "Flore Francaise." During this period he entered as a student of the Faculte de Theologie at Tours. About 1820 he was turned to the study of philosophy, probably through an acquaintance with John Stuart Mill. He next became the manager of his father's estates near Montpellier, and it was here that he wrote his first serious work, an "Essai sur la Classification des Arts et Sciences." In 1826 the Benthams returned to England, where he made many friends, among whom was Dr. Arnott; and it was in his company that Bentham, in 1824, paid a long visit to the Pyrenees, the fruits of which was his first botanical work, "Catalogue des Plantes indigenes des Pyrenees, etc." 1826. About this time Bentham entered Lincoln's Inn with a view to being called to the Bar, but the greater part of his energies was given to helping his Uncle Jeremy, and to independent work in logic and jurisprudence. He published his "Outlines of a New System of Logic" (1827), but the merit of his work was not recognised until 1850. In 1829 Bentham finally gave up the Bar and took up his life's work as a botanist. In 1854 he presented his collections and books (valued at 6,000 pounds) to the Royal Gardens, Kew, and for the rest of his life resided in London, and worked daily at the Herbarium. His work there began with the "Flora of Hong Kong," which was followed by that of Australia published in 1867 in seven volumes octavo. At the same time the "Genera Plantarum" was being planned; it was begun, with Dr. Hooker as a collaborator, in 1862, and concluded in 1883. With this monumental work his labours ended; "his strength...suddenly gave way...his visits to Kew ended, and lingering on under increasing debility, he died of old age on September 10th last" (1883.) The amount of work that he accomplished was gigantic and of the most masterly character. In speaking of his descriptive work the writer (Sir J.D. Hooker) of the obituary notice in "Nature" (October 2nd, 1884), from which many of the above facts are taken, says that he had "no superior since the days of Linnaeus and Robert Brown, and he has left no equal except Asa Gray" ("Athenaeum," December 31st, 1850; "Contemporary Review," May, 1873; "George Bentham, F.R.S." By Sir J.D. Hooker, "Annals Bot." Volume XII., 1898). -mentioned. -address to Linnean Society. -Darwin's criticism on address. -letters to. -extract from letter to. -views on species and on "Origin." -on fertilisation mechanism in Goodeniaceae. -on hybridism. -runs too many forms together. -on Scott's Primula paper. Berberis, Pfeffer on stamens. Berkeley, Miles Joseph (1803-89): was educated at Rugby and Christ's College, Cambridge; he took orders in 1827. Berkeley is described by Sir William Thiselton-Dyer as "the virtual founder of British Mycology" and as the first to treat the subject of the pathology of plants in a systematic manner. In 1857 he published his "Introduction to Cryptogamic Botany." ("Annals of Botany," Volume XI., 1897, page ix; see also an obituary notice by Sir Joseph Hooker in the "Proc. Royal Society," Volume XLVII., page ix, 1890.) -address by. -experiments on saltwater and seed-dispersal. -letter to. -mentioned. -notice of Darwin's work by. Bermudas, American plants in. -coral-reefs. Berzelius, on flints. Bhootan, Rhododendron Boothii from. Bible, chronology of. Biffen, R., potato grafts. Bignonia, F. Muller's paper on. -B. capreolata, tendrils of. Binney, Edward William F.R.S. (1812-81): contributed numerous papers to the Royal, Palaeontographical, Geological, and other Societies, on Upper Carboniferous and Permian Rocks; his most important work deals with the internal structure of Coal-Measure plants. In a paper "On the Origin of Coal," published in the "Memoirs of the Manchester Literary and Philosophical Society," Volume VIII., page 148, in 1848, Binney expressed the view that the sediments of the Coal Period were marine rather than estuarine, and were deposited on the floor of an ocean, which was characterised by a "uniformity and shallowness unknown" in any oceanic area of the present day. -on marshes of Coal period. -on coal and coal plants. Biogenesis, Huxley's address on abiogenesis and. Biology, Huxley's "Course of Practical Instruction" in. Biology of plants, Hooker's scheme for a Flora, with notes on. Birds, as agents of dispersal of plants. -blown to Madeira. -climate and effect on American. -coloration of. -comparison with mammals. -as isolated groups. -of Madeira. -modification in. -Andrew Murray on Wallace's theory of nests. -Wallace's theory of nests. -agents in dispersal of land-molluscs. -antics during courtship. -courtesy towards own image. -expression of fear by erection of feathers. -means of producing music. -spurs on female. -pairing. -polygamy. -proportion of sexes. -sexual selection and colour. -attracted by singing of bullfinch. -tameness in Brazilian species. -occurrence of unpaired. -Weir's observations on. Bird of paradise, and polygamy. Birmingham, British Association meeting (1849). Bivalves, means of dispersal of freshwater. Bizcacha, burrowing animal of Patagonia. Blackbird, variation in tufted. Blair, Rev. R.H., observations on the blind. Blake, paper on Elephants in "Geologist." Blanford, H.F., on an Indo-oceanic continent. Blanford, W.T., obituary notice of Neumayr by. Blind, expression of those born. Blomefield, L., see Jenyns, L. Bloom, Darwin's work on. -F. Darwin on connection between stomata and (see also Darwin, F.) -effect of rain on. -on leaf of Trifolium resupinatum. -protection against parasites. -on seashore plants. Blow-fly, Lowne on the. Blyth, Edward (1810-73): distinguished for his knowledge of Indian birds and mammals. He was for twenty years Curator of the Museum of the Asiatic Society of Bengal, a collection which was practically created by his exertions. Gould spoke of him as "the founder of the study" of Zoology in India. His published writings are voluminous, and include, in addition to those bearing his name, numerous articles in the "Field, Land and Water," etc., under the signature "Zoophilus" or "Z." He also communicated his knowledge to others with unsparing generosity, yet-- doubtless the chief part of his "extraordinary fund of information" died with him. Darwin had much correspondence with him, and always spoke of him with admiration for his powers of observation and for his judgment. The letters to Blyth have unfortunately not come into our hands. The indebtedness of Darwin to Blyth may be roughly gauged by the fact that the references under his name in the index to "Animals and Plants" occupy nearly a column. For further information about Blyth see Grote's introduction to the "Catalogue of Mammals and Birds of Burma, by the late E. Blyth" in the "Journal of the Asiatic Society of Bengal," Part II., Extra number, August 1875; also an obituary notice published at the time of his death in the "Field." Mr. Grote's Memoir contains a list of Blyth's writings which occupies nearly seven pages of the "Journal." We are indebted to Professor Newton for calling our attention to the sources of this note. -reference to letter from. -visits Down. -on Gallinaceae. Blytt, Axel Gudbrand (1843-98): the son of the well-known systematist M.N. Blytt. He was attached to the Christiania Herbarium in 1865, and in 1880 became Professor of Botany in the University. His best-known work is the essay referred to above, but he was also known for purely systematic work in Botany as well as for meteorological and geological contributions to science. The above facts are taken from C. Holtermann's obituary notice in the "Berichte der Deutschen Bot. Gesell." Volume XVII., 1899. -essay on immigration of Norwegian flora during alternating rainy and dry periods. -letter to. Bog-Mammoth. Boiler, comparison with volcano. Boissier, on plants of S. Spain. Boissiera, crossing experiments on. Bolbophyllum, Darwin's account of. Bolivia, geology of. Bollaert's "Antiquities of S. America." Bombus, diversity in generative organs. -Psithyrus in nests of. -Pollen-collecting apparatus of male. Bombycilla, protective colours. Bombyx, sexes in. Bonaparte, L., on Basque and Finnish language. Bonatea speciosa, F. Muller on. -structure of flower. Bonney's Edition of Darwin's "Coral Reefs." -"Charles Lyell and Modern Geology." Bonnier, G., on alpine plants. Boragineae, dimorphism in. Borneo, New Zealand and Australian plants in. -temperate plants in lowlands. -possible region for remains of early man. Bory's Flora of Bourbon. Bosquet, cirripede monograph sent by Darwin to. -gives Darwin note on fossil Chthamalus. Botanical collections (national) consolidation at Kew. Botanist, Darwin as. Botany, philosophical spirit in study of. Boulders, transport of erratic (see also Erratic blocks). -Darwin on Ashley Heath. -in Glen Roy. -on Moel Tryfan. Bourbon, Bory's Flora of. Bournemouth, Darwin's visit to. Bovey Tracey, Heer on fossil plants of. Bower, Prof. F.O., on Welwitschia. Bower-bird, Bartlett's experiments on. -colours discriminated by. Bowman, W., Letters to. -supplies Darwin with facts on Expression. Brachiopods, Morse on. -Silurian. Brackish-water plants. Bradshaw, H., translation of Hebrew letter by. Brain, Owen on. -evolution in man. -Wallace on Natural Selection and Evolution of. Branchipus, Schmankewitsch's experiments on. Branta, mentioned in reference to nomenclature of Barnacles. Brassica sinapistrum, germination at Down of old seeds. Braun, A., convert to Darwin's views. Bravais, on lines of old sea-level in Finmark. Brazil, L. Agassiz's book on. -Agassiz on glacial phenomena in. -F. Muller's residence in. -plants on mountains of. -basalt in association with granite. -Darwin on origin of lakes in. -dimorphism of plants in S. Bree, Dr., on Celts. -misrepresents Darwin. Breeders, views on Selection held by. Breeding, chapter in "Origin" on. Brehm, on birds. Breitenbach, Dr. Brewster, Sir D., on Glen Roy. Bridgeman. Brinton, Dr., attends Darwin. British Association, Meetings: Belfast (1874), Birmingham (1849), Cambridge (1862), Ipswich (1851), Leeds (1858), Liverpool (1870), Manchester (1861), Norwich (1868), Nottingham (1866), Oxford (1847), Oxford (1860), Southampton (1846), Swansea (1880), York (1881). Addresses: Berkeley, Fawcett, Hooker, Hooker on Insular Floras, (see also Hooker, Sir J.D.), Huxley on Abiogenesis, Lord Kelvin, Wallace on Birds' Nests. British Association, Committee for investigation of Coral Atoll by boring. British Medical Association, undertakes defence of Dr. Ferrier. British Museum, disposal of Botanical Collections. Brodie, Sir Benjamin. Brongniart, Ad., on Sigillaria. Bronn, H.G., Letter to. -on German translation of "Origin." -reference in his translation of "Origin" to tails of mice as difficulty opposed to Natural Selection. -on Natural Selection. -"Entwickelung." -"Morphologische Studien." -"Naturgeschische der drei Reiche." Brougham, Lord, on Structure of Bees' cells. -habit of writing everything important three times. Brown, H.T., and F. Escombe, on vitality of seeds. -on influence of varying amounts of CO2 on plants. Brown, R., accompanies Flinders on Australian voyage. -meets Darwin. -dilatoriness over King's collection. -illness. -on course of vessels in orchid flowers. -mentioned. -on pollen-tubes. -seldom indulged in theory. Brulle, Gaspard-Auguste (1809-73): held a post in the Natural History Museum, Paris, from 1833 to 1839; on leaving Paris he occupied the chair of Zoology and Comparative Anatomy at Dijon. ("Note sur la Vie et les Travaux Entomologiques d'Auguste Brulle" by E. Desmarest. "Ann. Soc. Entom." Volume II., page 513.) -reference to work by. -his pupils' eagerness to hear Darwin's views. Brunonia, Hamilton on fertilisation mechanism. Brunton, Sir T. Lauder, letters to. -letter to Darwin from. Brydges and Anderson, collection of S. American plants. Bryophyllum calycinum, Duval-Jouve and F. Muller on movements of leaves. Bryozoa, specimens found during voyage of "Beagle." Buch, von, on craters of Albermarle I. -Darwin's disbelief in his views. -mentioned. -"Travels in Norway." Buckland, William (1784-1856): became a scholar of Corpus Christi College, Oxford, in 1801; in 1808 he was elected Fellow and ordained priest. Buckland travelled on horseback over a large part of the south-west of England, guided by the geological maps of William Smith. In 1813 he was appointed to the Chair of Mineralogy at Oxford, and soon afterwards to a newly created Readership in Geology. In 1823 the "Reliquiae Diluvianae" was published, a work which aimed at supporting the records of revelation by scientific investigations. In 1824 Buckland was President of the Geological Society, and in the following year he left Oxford for the living of Stoke Charity, near Whitchurch, Hampshire. "The Bridgewater Treatise" appeared in 1836. In 1845 Buckland was appointed Dean of Westminster; he was again elected president of the Geological Society in 1840, and in 1848 he received the Wollaston medal. An entertaining account of Buckland is given in Mr. Tuckwell's "Reminiscences of Oxford," London, 1900, page 35, with a reproduction of the portrait from Gordon's "Life of Buckland." -on Glen Roy. -mentioned. Buckle, Darwin reads book by. Buckley, Miss. Buckman, on N. American plants. Buckman, Prof., experiments at Cirencester. Bud, propagation by. -Hooker's use of term. -fertilisation in. Bud-variation. Buenos-Ayres, fossils sent by Darwin from. Bull-dog, as example of Design. Bullfinch, experiment on colouring. -attracted by German singing-bird. -Weir on pairing. Bunbury, Sir Charles James Fox, Bart. (1809-85): was born at Messina in 1809, and in 1829 entered Trinity College, Cambridge. At the end of 1837 he went with Sir George Napier to the Cape of Good Hope, and during a residence there of twelve months Bunbury devoted himself to botanical field-work, and afterwards (1848) published his "Journal of a Residence at the Cape of Good Hope." In 1844 Bunbury married the second daughter of Mr. Leonard Horner, Lady Lyell's sister. In addition to several papers dealing with systematic and geographical Botany Bunbury published numerous contributions on palaeobotanical subjects, a science with which his name will always be associated as one of those who materially assisted in raising the study of Fossil Plants to a higher scientific level. His papers on fossil plants were published in the "Journal of the Geological Society" between 1846 and 1861, and shortly before his death a collection of botanical observations made in South Africa and South America was issued in book form in a volume entitled "Botanical Fragments" (London, 1883). Bunbury was elected into the Royal Society in 1851, and from 1847 to 1853 he acted as Foreign Secretary to the Geological Society. "Life, Letters, and Journals of Sir Charles J.F. Bunbury, Bart." edited by his wife Frances Joanna Bunbury, and privately printed. (Undated.) -Darwin's opinion of. -views on Evolution. -on Agassiz's statements on glaciation of Brazil. -on plants of Madeira. -illness. -mentioned. Bunsen, Copley medal awarded to. -mentioned. Burbidge, F.W., on Malaxis. Burleigh, Lord. Burnett. Busk, G., visit to the Continent with Falconer. -on caves of Gibraltar. Butler, A.G., identification of butterflies. Butler, Dr., Darwin at Shrewsbury School under. -mentioned. Butterflies, attracted by colours. -and mimicry. -tameness of. -colour and sexual selection. -description by Darwin of ticking. Butterfly-orchis, (see also Habenaria.) Cabbage, Darwin's work on. -effect of salt water on. -Pinguicula and seeds of. -sleep-movements of cotyledons. -waxy secretion on leaves. Caddis-flies, F. Muller on abortion of hairs on legs of. Caenonympha, breeding in confinement. Caird, on Torbitt's potato experiments. Calcutta, J. Scott's position in Botanic Garden. Callidryas philea, and Hedychium. Callithrix Sciureus, wrinkling of eyes during screaming. Calluna vulgaris, in Azores. Cambrian, piles of unconformable strata below. Cambridge, Darwin and Henslow. -Honorary LL.D. given to Darwin. -mentioned. -Darwin's recollections of. -Owen's address. -Philosophical Society meeting. -Darwin visits. -specimens of Darwin's plants in Botanical Museum. Camel, Cuvier's statement on teeth. -in N. America. Cameroons, commingling of temperate and tropical plants. -Hooker on plants of. -plants of. Campanula, fertilisation mechanism. -C. perfoliata, note by Scott on. Campanulaceae, crossing in. Campbell Island, flora. Campodea, Lord Avebury on. Canada, Sir William Dawson's work. Canaries, fertility of hybrids. -plumage. -wildness of hybrids. Canary Islands, flora. -Humboldt on. -insects of. -Madeira formerly connected with. -relation to Azores and Madeira. -d'Urville on. -African affinity of eastern. -elevation of. -Von Buch on. -Trunks of American trees washed on shores of. Candolle, Alphonse Louis Pierre Pyramus De (1806-93): was the son of Augustin Pyramus, and succeeded his father as Professor of Botany at Geneva in 1835. He resigned his Chair in 1850, and devoted himself to research for the rest of his life. At the time of his father's death, in 1841, seven volumes of the "Prodromus" had appeared: Alphonse completed the seventeenth volume in 1873. In 1855 appeared his "Geographie botanique raisonnee," "which was the most important work of his life," and if not a precursor, "yet one of the inevitable foundation-stones" of modern evolutionary principles. He also wrote "Histoire des Savants," 1873, and "Phytographie," 1880. He was lavish of assistance to workers in Botany, and was distinguished by a dignified and charming personality. (See Sir W. Thiselton-Dyer's obituary in "Nature," July 20th, 1893, page 269.) -on influence of climate. -on Cupuliferae. -on extinction of plants in cultivated land. -"Geographie botanique." -letters to. -on introduced plants. -on naturalised plants and variation. -review by Asa Gray of. -on relation of size of families to range of species. -on social plants. -mentioned. Candolle, C. de, on latent life in seeds. Canestrini, on proportion of sexes in Bombyx. Canna, fertilisation of. Cape of Good Hope (see also Africa). -Australian flora compared with that of. -flora. -variable heaths of. -Darwin's geological observations on metamorphism at. -European element in flora. -Meyer and Doege on plants of. Cape Tres Montes, the "Beagle's" southern limit. Caprification, F. Muller in "Kosmos" on. Capsella bursa-pastoris, cross-fertilisation of. Carabus, origin of. -in Chili. -A. Murray on. Carbon dioxide, percentage in atmosphere. Carboniferous period, glacial action. -subsidence during. Cardamine, quasi-bulbs on leaves. Carduelis elegans, length of beak. Carex. Carices, of Greenland. Carlisle, Sir A., on Megatherium. Carlyle, Mrs., remark on Owen. Carmichael, on Tristan d'Acunha. Carmichaelia. Carnarvonshire, Darwin on glaciers of. Caroline Islands, want of knowledge on flora. Carpenter, Dr., on influence of blood in crossing. Carrier-pigeon (see Pigeon), preference for certain colours in pairing. Carrot, flowers of. Carruthers, W., on potato experiments. Carter, H.J., on reproduction of lower animals and foreshadowing of Chemotaxis. Carus, Professor Victor: translated several of Mr. Darwin's books into German (see "Life and Letters, III., page 48). -letters to. Casarea, a snake peculiar to Round Island. Case, G., Darwin at school of. Cassia, Darwin's experiments on. -sleep-movements of leaves. -two kinds of stamens. -Todd on flowers of. Cassini, observations on pollen. -on ovaries of Compositae. Cassiope hypnoides. Castes, Galton on. Catalpa. Catasetum, fertilisation of. -Huxley's scepticism as to mechanism of. -morphology of flower. -aerial roots. -sexual forms of. -C. saccatum, flower of. -C. tridentatum, three sexual forms. Caterpillars, colour and protection. -experiments by Weir. Cats, Belgian society to encourage homing of. -habits of. Cattell, on crossing sweet peas. Cattleya, Darwin suggests experiments on. -self-fertilisation. Caucasus, wingless insects of. Cauquenes, baths of. Cave-fish, reference in the "Origin" to blind. Cave-rat. Caves, animals in Australian. Cavia, specimens collected by Darwin. Ceara Mountains, L. Agassiz on glaciers of. Cebus, expression when astonished. Cecidomyia, ancestor of. Cedars, Hooker on. Celebes, geographical distribution in. Cellaria. Celosia, experiment on. Celts, Bree on. Centipedes, luminosity of. Centradenia, two sets of stamens in. -position of pistil. Cephalanthera, flower. -single pollen-grains. -C. grandiflora, fertilisation mechanism. Cephalopods, Hyatt on embryology of. -Hyatt on fossil. Cephalotus. Cervus campestris, of La Plata. Cetacea, Lyell on. Ceylon, Malayan types in. -plants. -former connection with Africa. -dimorphic plants of. Chaffinch, courtship of. Chalazal fertilisation, Miss Benson on. -foreshadowed by Darwin. -Treub on. Chalk, occurrence of Angiosperms in. -as oceanic deposit. "Challenger" (H.M.S.), reports reviewed by Huxley. -account of sedimentation in. Challis, Prof. Chambers, Robert (1802-71): began as a bookseller in Edinburgh in 1816, and from very modest beginnings he gradually increased his business till it became the flourishing publishing firm of W. & R. Chambers. After writing several books on biographical, historical and other subjects, Chambers published anonymously the "Vestiges of the Natural History of Creation" in 1844; in 1848 his work on "Ancient Sea Margins" appeared; and this was followed by the "Book of Days" and other volumes. ("Dict. Nat. Biog." 1887; see also Darwin's "Life and Letters," I., pages 355, 356, 362, 363.) -announced as author of "Vestiges of Creation." -on derivation of marine from land and fresh-water organisms. -Darwin visits. -on Glen Roy. -on land-glaciation of Scotland. -letters to. -letter to Milne-Home from. -on scepticism of scientific men. -mentioned. Chance, use of term. Chandler, S.E. (see Farmer, J.B.) Changed conditions, Schmankewitsch's experiments on effect of. Charles Island, Darwin's plants from. Charlock, germination of old seeds. Chatham Island, Darwin's collection of plants from. -Travers on. Checks, use of artificial. Chemotaxis, foreshadowed by Carter. Chiasognathus Grantii. Childhood, Charles Darwin's. Children, Darwin on. -experiment on emotions of. -colour-sense. -coloured compared with white. -comparison between those of educated and uneducated parents. -expression. -development of mind. -intelligence of monkeys and. Chili, elevation of coast. -geology of. -plants common to New Zealand and. -Carabus of. -Darwin on earthquakes and terraces in. Chillingham cattle, Darwin and Hindmarsh on. Chiloe, description of. -forests. -geology. -plants on mountains. -boulders. China, expedition to. Chinese, explanation of affinities with Mexicans. "Chips from a German Workshop," Max Muller's. Chloeon dimidiatum, Lord Avebury on. Chlorite, segregation of. Chlorophyll, Darwin's work on action of carbonate of ammonia on. Chonos Islands, Darwin's collections of plants from. -Darwin's account of. -geology of. -potato. Christy, H. Christy, Miller, on oxlip. Chrysosplenium oppositifolium. Chthamalus, in the chalk. Cicada, experiments on eggs. -Muller on rivalry of. -Walsh on. -C. septendecim, Sharp's account of. Cinchona, Hooker on different rates of growth in seedlings. Circumnutation, F. Muller's observations on. Cirripedes, see Barnacles. Cistus, hybridism of. Citrus, unequal cotyledons. -polyembryonic seeds. Civilisation, effect on savages. Claparede, convert to Darwin's views. -and Mdlle. Royer. Clapperton's "Scientific Meliorism," letter of Gaskell in. Clark, on classification of sponges. Clark, Sir James (1788-1870): was for some years a medical officer in the Navy; he afterwards practised in Rome till he moved to London in 1826. On the accession of Queen Victoria he was made Physician in Ordinary and received a baronetcy; he was elected into the Royal Society in 1832. ("Dict. Nat. Biog." 1857; article by Dr. Norman Moore.) -on Glen Roy. Clarke, W.B., "Wreck of the 'Favourite.'" Clarkia, two kinds of stamens. -C. elegans. Classification, Bentham on. -Cuvier on. -Dana on mammalian. -Darwin on. -Darwin and Huxley on. -genealogy and. -value of reproductive organs in. Clay-slate, metamorphism of. Cleavage and foliation. -Darwin on his work on. -history of work on. -parallelism of foliation and. -relation to stratification. -relation to rock-curves. -Rogers on. -Sedgwick on. -uniformity of foliation and. -result of chemical action. -metamorphic schists. -lines of incipient tearing form planes of. -Tyndall on Sorby's observations. Cleistogamic flowers, fertilisation. -of grass. -of Oxalis and Viola. -pollen of. -comparison with Termites. Clematis, Darwin's error in work on. -Darwin's experiments on. -irritability. Clematis glandulosa, identified at Down by power of feeling. Cleodora, specific differences in. Clethra, absence in Azores. -remnant of Tertiary Flora. Clianthus. Clift, William (1775-1849): Conservator of the Museum of the Royal College of Surgeons. -on fossil bones from Australia. -Owen assistant to. Climate, changes in. -effect on species. -effect on species of birds. -migration of organisms and change in. -relation to distribution and structure of plants. -extinct mammals as evidence of change in. -and sexual differentiation. -variation and. -Lyell on former. -mild Miocene. Climbing Plants, Darwin's work on. -circumnutation of. -F. Muller's work on. Clivia, Scott's work on. Clodd's memoir of Bates. Close species, absence of intermediate forms between. -definition of. -Asa Gray on. -in warm temperate lands of N. and S. hemispheres. -relation to flora of N. America. Clover, relation between bees and. Club, dinner at Linnean. -Philosophical. Coal, Darwin on origin of. -Lesquereux on the flora of. -marine marshes and plants of. -ash of. Coal period, higher percentage of CO2 during. Coast-lines, parallelism with lines of volcanoes. Cobbe, Miss, article in "Theological Review" on "Descent of Man." Cockburn Island, boulders from. Cochin hen, experiments on. Coelogyne, fertilisation mechanism. Coffea arabica, seeds with two embryos. Cohn, F., notice in "Cornhill" of his botanical work. Coldstream, Dr. Colenso, on Maori races of New Zealand. Coleoptera, apterous form of Madeira. -colonisation of ants' nests by. Colias edusa, wings of. Collecting, Darwin's early taste for. Collier, Hon. John: Royal Academician, son-in-law to Professor Huxley. -Art primer by. -letter to. -portrait of Darwin by. Collingwood, Dr., on mimetic forms. Colonies, Barrande's. Colonisation, conditions of. Coloration, Walsh on unity of. Colour, butterflies attracted by. -mimicry in butterflies by means of. -of dioecious flowers. -and fertilisation of flowers. -in grouse, and Natural Selection. -in birds. -in male birds, not simply due to Natural Selection. -Darwin's work on. -Darwin differs from Wallace in views on. -evolution of. -experiments on birds. -Hackel on lower animals and. -Krause on. -Magnus on. -protection and. -relation to sex. -in seeds and fruits. -and Sexual Selection. -sense of, in children. -Wallace on. Columba aenas, habits of. -C. livia, descent of pigeons from. Combretum. Combs, bees', (see also Bees). Comparative anatomy, Huxley's book on. Compensation, belief of botanists in. Compiler, Darwin's opinion of a. Compositae, Harvey on. -Masters' reference to. -monstrosities in. -morphological characters. -Schleiden on. -Darwin on crossing. -fertilisation mechanism. -Hildebrand on dispersal of seeds. -viscid threads of seeds. Comte, Huxley on. Concepcion Island, geology of. -Darwin's account of earthquake. Conchoderma, in reference to nomenclature. Concretions, origin of. Conditions of life, effect on animals and plants. -effect on elephants. -effect on reproductive system. -hybrids and. -importance in maintaining number of species. -species and changes in. -and sterility. -variability depends more on nature of organisms than on. Confervae and sexuality. Coniferae, abundant in humid temperate regions. Connecting links. -Gaudry on. Conscience, Morley on Darwin's treatment of. Conspectus crustaceorum, Dana's. Constancy, in abnormally developed organs. Contemporaneity, Darwin on. Continental elevation, volcanic eruptions and. Continental extension, Darwin on. -evidence in favour of. -Hooker on. -Lyell on. -and means of distribution. -New Zealand and. Continental forms, versus insular. Continents, inhabitants of islands and. -movements of. -Wallace on sinking imaginary. Controversy, Darwin's hatred and avoidance of. Convallaria majalis, in Virginia. Convolvulus, supposed dimorphism of. Cooling of crust, disagreement among physicists as to rate. Cope, Edward Drinker (1840-97): was for a short time Professor at Haverford College; he was a member of certain United States Geological Survey expeditions, and at the time of his death he held a Professorship in the University of Pennsylvania. He wrote several important memoirs on "Vertebrate Paleontology," and in 1887 published "The Origin of the Fittest." -style of. -and Hyatt, theories of. Copley medal, Darwin and the. -Falconer, and Darwin's. -Lindley considered for the. -awarded to Lyell. -awarded to Bunsen. -Darwin describes letter from Hooker as a. Coquimbo, Darwin visits. -upraised shells. Coral islands, and subsidence. -plants of. Coral reefs, Darwin's work on. -Bonney's edition of Darwin's book on. -A. Agassiz on. -Dana on. -fossil. -Murray on. -conditions of life of polyps. -solution by CO2 of. -subsidence of. Coral tree, (see Erythrina). Corallines, nature of. Cordiaceae, dimorphism in. Cordilleras, glaciers of. -high-road for plants. -plants of. -birds of. -comparison between Glen Roy and terraces of. -Darwin on earth-movements of. -Forbes on. -submarine lava-streams. -volcanic activity and elevation. Coronilla, Lord Farrer on. -C. emerus. -C. varia. Coryanthes, "beats everything in orchids." Corydalis, Hildebrand shows falsity of idea of self-fertilisation of. -C. cava, Hildebrand on self-sterility of. -C. claviculata, tendrils of. -C. tuberosa, possible case of reversion in floral structure. "Cottage Gardener," Darwin offers reward for Hyacinth grafts. Cotyledons, Darwin's experiments on. Counterbalance, Watson on divergent variation and. Cowslips, Primroses and. -Darwin's experiments on artificial fertilisation. -homomorphic seedlings. -loss of dimorphism. Craig Dhu, shelves of. Craters, in Galapagos Island. -of denudation, Lyell on. -of elevation. -Darwin on. Crawford, John (1783-1868): Orientalist, Ethnologist, etc. Mr. Crawford wrote a review on the "Origin," which, though hostile, was free from bigotry (see "Life and Letters," II., page 237).) Creation, acts of. -doctrine of. -of species as eggs. -Owen on. -Romanes on individual. Creation-by-variation, doctrine of. "Creed of Science," Graham's. Cresy, E., letters to. Cretaceous flora, Heer on Arctic. Crick, W.D., letter to. Crinum, crossing experiments on. -C. passiflora, fertility of. Crocker, W., work on hollyhocks. Croll, James (1821-90): was born at Little Whitefield, in Perthshire. After a short time passed in the village school, he was apprenticed as a wheelwright, but lack of strength compelled him to seek less arduous employment, and he became agent to an insurance company. In 1859 he was appointed keeper in the Andersonian University and Museum, Glasgow. His first contribution to science was published in the "Philosophical Magazine" for 1861, and this was followed in 1864 by the essay "On the Physical Cause of the Change of Climate during the Glacial Period." From 1867 to 1881 he held an appointment in the department of the Geological Survey in Edinburgh. In 1876 Croll was elected a Fellow of the Royal Society. His last work, "The Philosophical Basis of Evolution," was published in the year of his death. ("Nature," Volume XLIII., page 180, 1891.) -Darwin on his theory. -on icebergs as grinding agents. -letters to. -Lyell on his theory. -on sub-aerial denudation. -on time. Crookes, Sir W., on spiritualism. "Cross and Self-fertilisation," Darwin's book on. Cross-fertilisation, Darwin's experiments on self- and. -check to endless variability. -Darwin states that as a rule flowers described as adapted to self- fertilisation are really adapted to. -of inconspicuous flowers. -all plants require occasional. -small advantages when confined to same plant. Crosses, fertility and sterility of. Crossing, agreement between Darwin's and breeders' views. -counterbalance of. -Darwin's views on. -effects of. -experiments on. -Hooker's views. -in animals and plants. -influence of blood in. -intermediate character of results. -Natural Selection and disinclination towards. -offspring of. -of primroses and cowslips. -and sterility. -Westphalian pig and English boar. -botanists' work on. -importance of. -pains taken by Nature to ensure. -in Pisum. -in Primula. -in individuals of same species. -F. Muller compliments Darwin on his chapter on. -and separate sexes in trees. Crotalaria. Crotalus. Cruciferae, action of fungus on roots. Cruciferous flower, morphology. Cruger, Dr., on cleistogamic fertilisation of Epidendrum. -death of. -on fertilisation of figs. -on pollinia of Acropera. -on Melastomaceae. -on fertilisation of orchids. Crustacea, comparison of classification of mammals and. -Darwin on. -F. Muller on. -sex in. Crying, action of children in. -physiology of. -wrinkling of eyes in. Crystal Palace, Darwin's visit to. Crystals, separation in lava-magmas. Cucurbita, seeds and seedlings of. Cucurbitaceae, Dr. Wight on. Cudham Wood. Cultivated plants, Darwin's work on. Cultivation and self-sterility. Cuming, on Galapagos Islands. Cupuliferae, A. de Candolle on. Curculionidae, Schoenherr's catalogue. Currents, as means of dispersal. Cuvier, on camels' teeth. -on classification. -mentioned. Cybele, H.C. Watson's. Cycadaceae, supposed power to withstand excess of CO2. Cyclas cornea. Cyclops (H.M.S.) dredging by. Cynips, dimorphism in. -Walsh on. Cypripedium, fertilisation mechanism. -C. hirsutissimum. Cyrena, range and variability. Cytisus Adami, Darwin on. -note on. -C. alpinus. -C. laburnum, graft-hybrids between C. purpureus and. -J.J. Weir on. Cyttarogenesis, suggested substitute for pangenesis. Dallas, W.S., translator of F. Muller's "Fur Darwin." Dampiera, Hamilton on fertilisation mechanism. Dana, James Dwight (1813-95): published numerous works on Geology, Mineralogy, and Zoology. He was awarded the Copley Medal by the Royal Society in 1877, and elected a foreign member in 1884. -Darwin's opinion of. -health. -letters to. -mentioned. -on classification of mammalia. -Darwin's criticism of. -on Kilauea. -Lyell on his claims for Royal Society foreign list. -volume on geology in Wilkes' Reports. Dareste, C., letter to. Darwin, Annie: Charles Darwin's daughter. Darwin, Bernard: Charles Darwin's grandson, observations on, as a child. Darwin, Caroline (1800-99): Charles Darwin's sister. -Charles Darwin's early recollections of. -letter to. Darwin, Catherine (1810-66): Charles Darwin's sister. -death. -letter to. Darwin, Charles, boyhood. -went to Mr. Case's school. -went to Shrewsbury School. -abused as an atheist. -Collier's picture of. -complains of little time for reading. -contribution to Henslow's biography. -Copley medal awarded to. -engagement to Miss Emma Wedgwood. -Falconer's list of scientific labours of. -first meeting with Hooker. -friendship with Huxley. -on Gray's work on distribution. -growth of his evolutionary views. -health. -honorary degree at Cambridge. -intimacy with Hooker. -Judd's recollections of. -Lamarck and. -letters to "Nature." -marriage. -friendship with F. Muller. -prefatory note to Meldola's translation of Weismann. -recollections of Cambridge. -relation between J. Scott and. -review on Bates. -attends meeting of Royal Society. -slowness in giving up old beliefs. -tendency to restrict interest to Natural History. -and the "Vestiges." -visits London. -Wallace and. -and Weismann. -working hours. -book on S. American Geology. -pleasure in angling. -on making blunders. -slight knowledge of Botany. -visits Cambridge. -love of children. -on cleavage and foliation. -on origin of coal. -his theory of Coral reefs supported by Funafuti boring. -large correspondence. -on danger of trusting in science to principle of exclusion. -death of his child from scarlet fever. -on difficulty of writing good English. -feels need of stimulus in work. -subscribes to Dr. Ferrier's defence. -on flaws in his reasoning. -follows golden rule of putting adverse facts in strongest light. -"Geological Instructions." -geological work on Lochaber. -visit to Glen Roy. -bad handwriting. -idleness a misery. -on immortality and death. -on lavas. -letter to "Scotsman" on Glen Roy. -indebtedness to Lyell. -on Lyell as a geologist. -on Lyell's "Second Visit to the U.S.A." -work on Man and Sexual Selection. -on mountain-chains. -offer of help to F. Muller. -never afraid of his facts. -an honorary member of the Physiological Society. -pleasure in discussing Geology with Lyell. -reads paper before Linnean Society. -A. Rich leaves his fortune to. -on satisfaction of aiding fellow-workers in Science. -reminiscences of school-days. -visits Sedgwick. -sits to an artist. -on speculation. -style in writing. -gives testimonial in support of Hooker's candidature for Botanical Chair in Edinburgh. -theological abuse in the "Three Barriers." -visits to Abinger. -visit to Patterdale. -on vitality of seeds. -on volcanic phenomena. -on Welsh glaciers. -work on action of carbonate of ammonia on plants. Darwin, Mrs. Charles, impressions of Down. -letter to. -passage from Darwin's autobiography on. -mentioned. -illness. Darwin, Emma, see Mrs. Charles Darwin. Darwin, Erasmus Alvey (1804-81): elder brother of Charles Darwin. -death of. -letters to. -mentioned. -visit to. Darwin, Dr. Erasmus: Charles Darwin's grandfather. -Charles Darwin's preliminary notice to Krause's memoir of. -Charles Darwin and evolutionary views of. Darwin, Francis: Charles Darwin's son. -on bloom and stomata. -on Dipsacus. -on Huxley's speech at Cambridge. -on the Knight-Darwin law. -on lobing of leaves. -experiments on nutrition. -experiments on plant-movements. -lecture at Glasgow (British Association, 1901) on perceptions of plants. -suggestion for Romanes' experiments on intelligence. -on vivisection. -on Vochting's work. -on Wiesner's work. Darwin, George: Charles Darwin's son. -success at Cambridge. -criticism of Wallace. -elected Plumian Professor at Cambridge. -suggested experiments with magnetic needles and insects. -on Galton's work on heredity. -article in "Contemporary Review" on origin of language. Darwin, Henrietta (Mrs. Litchfield): Charles Darwin's daughter. -criticism of Huxley. Darwin, Horace: Charles Darwin's son. -remark as a boy on Natural Selection. -mentioned. Darwin, Leonard: Charles Darwin's son. Darwin, Robert W.: Charles Darwin's father. -letter to. Darwin, Susan: Charles Darwin's sister. -alluded to in early recollections of Charles Darwin. -illness. -sends Wedgwood ware to Hooker. Darwin, William Erasmus: Charles Darwin's eldest son. -on fertilisation of Epipactis palustris. -letter to. "Darwin and after Darwin," Romanes'. "Darwiniana," Asa Gray's. -extract from Huxley's. "Darwinsche Theorie," Wagner's book. "Darwinism," Wallace's. Darwinismus, at the British Association meeting at Norwich (1868). Daubeny, Prof. Charles Giles Bridle, F.R.S. (1795-1867): Fellow of Magdalen College, Oxford; elected Professor of Chemistry in the University 1822; in 1834 he became Professor of Botany, and in 1840 Professor of Rural Economy. -invites Darwin to attend British Association at Oxford. -mentioned. David, Prof. Edgeworth, and the Funafuti boring. Dawn of life, oldest fossils do not mark the. Dawson, Sir J. William, C.M.G., F.R.S. (1820-99), was born at Pictou, Nova Scotia, and studied at Edinburgh University in 1841-42. He was appointed Principal of the McGill University, Montreal, in 1855,--a post which he held thirty-eight years. See "Fifty Years of Work in Canada, Scientific and Educational," by Sir William Dawson, 1901. -antagonism to Darwinism. -criticism of "Origin" by. -criticism of Hooker's arctic paper. -Hooker on. Dayman, Captain, on soundings. De la Beche, Sir Henry Thomas (1796-1855): was appointed Director of the Ordnance Geological Survey in 1832; his private undertaking to make a geological survey of the mining districts of Devon and Cornwall led the Government to found the National Survey. He was also instrumental in forming the Museum of Practical Geology in Jermyn Street. Death, Darwin on immortality and. Decaisne. Decapods, Zoea stage of. Dedication of Hackel's "Generelle Morphologie" to Darwin. Dedoublement, theory of. Deep-sea soundings, Huxley's work on. Degeneration, in ammonites. -of culinary plants. -and parasitism. Degradation. Deification of Natural Selection. Deinosaurus, and free-will. Delboeuf's "La Psychologie," etc. Delpino, F., on Asclepiadeae and Apocyneae. -on crossing. -on dichogamy. -on fertilisation mechanism. -letter to. -praises Axell's book. -mentioned. Demosthenes, quoted by Darwin. Denudation, Dana on. -Darwin on marine. -comparison of subaerial and marine. -Ramsay and Jukes overestimate subaerial. Deodar, Hooker on the. Deposition and denudation as measure of time. Derby, Lady, letter to. Descent, Falconer on intermediate forms. -from single pair. -Owen's belief in doctrine of. -resemblance due to. Descent of Man. "Descent of Man," reference in, to effect of climate on species. -reviewed by John Morley. -transmission of characters dealt with in. -Darwin's work on. -Sir W. Turner supplies facts for. -Wallace on. Descent with modification, Wallace on. Desert animals, and protective colouring. Design, Darwin on. -examples of. -Lord Kelvin on. Deslongchamps, L., on fertilisation of closed flowers. Desmodium gyrans, Darwin's experiments on. -leaf movements. Development, acceleration and retardation in. -floral. -importance of, in classification. -rate of. -sudden changes during. Devonshire Commission, report on physiological investigation at Kew. Devonshire, flora of. Dewar, Prof., and Sir Wm. Thiselton-Dyer, on vitality of seeds in liquid hydrogen. Diaheliotropism, F. Muller's observations. Dialogue, title of paper by Asa Gray. Diatomaceae, beauty of. -conjugation in. Dicentra thalictriformis, morphology of tendrils. Dichaea, fertilisation mechanism. Dichogamy, Delpino on. -ignorance of botanists of, prior to publication of "Fertilisation of Orchids." Dick, Sir T. Lauder, Survey of Glen Roy by. Dickens, quotation from. Dickson, Dr. Dickson, W.K. Dicotyledons, Heer on oldest known. -sudden appearance. Didelphys. Digestion, beneficial effect on plants. Dillwyn, paper in "Gardeners' Chronicle." Diluvium, tails of. Dimorphism, in Cynips. -Darwin on. -difficult to explain. -and mimicry. -in parasitic plants. -Wallace on. -Walsh on. -Weismann on Sexual. -in Cicadas. -flowers illustrating. -Darwin knows no case in very irregular flowers. -in Melastomaceae. -in Linum. -in eight Natural Orders. -in Primula. -apparent cases due to mere variability. -explanation of. Dingo. Diodia. Dioeciousness, origin of. Dionoea, experiments on. response to stimuli. Curtis' observations on. Dipsacus, F. Darwin on. Dipterocarpus, survival during glacial period. Direct action, arguments against. -Darwin led to believe more in. -Darwin's desire not to underestimate. -Darwin's underestimates. -facts proving. -Falconer on. -and hybridity. -importance of. -of pollen. -variation and. Direction, sense of, in animals. Disease, Dobell on "Germs and Vestiges" of. Dispersal, (see also Distribution), of seeds. -of shells. Distribution, Forbes on. -Hooker on Arctic plants. -of land and sea in former times. -of plants. -factors governing. -of shells. -Thiselton-Dyer on plant-. -Wallace on. -Blytt's work on. Disuse, Darwin on. -effect of. -Owen on. Divergence, Hooker on. -principle of. Diversification, Darwin's doctrine of the good of. Dobell, H., letter to. Dogs, descent of. -experiment in painting. -expression. -habits. -rudimentary tail inherited in certain sheep-. Dohrn, Dr., visits Darwin. -serves in Franco-Prussian war. -extract from letter to. "Dolomit Riffe," Darwin on Mojsisovics'. Domestic animals, crossing in. -Darwin's work on. -Settegast on. -variability of. -treatment in "Variation of Animals and Plants." Domestication, effects of. -and loss of sterility. Domeyko, on Chili. Dominant forms. Don, D., on variation. -mentioned. Donders, F.C., on action of eyelids. -letters to. Dorkings, power of flight. Down, description of house and country. -Darwin's satisfaction with his house. -instances of vitality of seeds recorded from. -method of determining plants at. -Darwin on geology of. -observations on regular lines of flight of bees at. Down (lanugo), on human body. Dropmore. Drosera, F. Darwin's experiments. -"a disguised animal." -Darwin's observations on. -Darwin's pleasure on proving digestion in. -effect of inorganic substance on. -experiments on absorption of poison. -Pfeffer on. -J. Scott's paper on. -response to stimuli. -D. filiformis, experiments on. -D. rotundifolia, experiments on. Drosophyllum, vernation of. -Darwin's work on. -Drosophyllum lusitanicum, sent by Tait to Darwin. -used in Portugal to hang up as fly-paper. Druidical mounds, seeds from. Drummond, J., on fertilisation in Leschenaultia formosa. Duchesne, on atavism. Ducks, period of hatching. -skeletons. -hybrids between fowls and. Dufrenoy, Pierre Armand: published "Memoires pour servir a une Description Geologique de la France," as well as numerous papers in the "Annales des Mines, Comptes Rendus, Bulletin Soc. Geol. France," and elsewhere on mineralogical and geological subjects. -geological work of. Duncan, Rev. J., encourages J. Scott's love for plants. Dung, plants germinated from locust-. Dutrochet, on climbing plants. Duval-Jouve, on leaf-movement in Bryophyllum. Dyer, see Thiselton-Dyer. Dytiscus, as means of dispersal of bivalves. Ears, loss of voluntary movement. -in man and monkeys. -rudimentary muscles. -Wallis's work on. Earth, age of the. Earth-movements, cause of. -in England. -relation to sedimentation. -subordinate part played by heat in. Earthquakes, coincidence of shocks in S. America and elsewhere. -connection with elevation. -connection with state of weather. -Darwin on. -in England. -frequency of. -Hopkins on. -in Scotland. Earthworms, Darwin's book on. -geological action of. -influence of sea-water on. -F. Muller gives Darwin facts on. -Typhlops and true. Echidna, anomalous character of. Edentata, migration into N. America. Edgeworth, mentioned. Edinburgh, Darwin's student-days in. -Hooker's candidature for Chair of Botany. "Edinburgh Review," article on Lyell's "Antiquity of Man." -reference to Huxley's Royal Institution Lectures. -Owen's article. Education, effect of. -influence on children of parents'. Edwardsia, seeds possibly floated from Chili to New Zealand. -in Sandwich Is. and India. Egerton, Sir Philip de Malpas Grey- (1806-81): devoted himself to the study of fossil fishes, and published several memoirs on his collection, which was acquired by the British Museum. Eggs, creation of species as. -means of dispersal of molluscan. Ehrenberg, Ascension I. plants sent to. -on rock-building by infusoria. -Darwin's wish that he should examine underclays. Eichler, A.W., on morphology of cruciferous flower. -on course of vessels as guide to floral morphology. -reference to his Bluthendiagramme. Eildon Hills, need of examination of. Elateridae, luminous thorax of. Elective affinity. Electric organs of fishes, the result of external conditions. Electricity, and plant-movements. "Elements of Geology," Wallace's review of Lyell's. Elephants, Falconer's work on. -rate of increase of. -and variation. -found in gravel at Down. -manner of carrying tail. -shedding tears. Elephas Columbi, Falconer on. -Owen's conduct in regard to Falconer's work on. -E. primigenius, as index of climate. -woolly covering of. -E. texianus, Owen and nomenclature of. Elevation, in Chili. -lines of. -New Zealand and. -continental extension, subsidence and. -connection with earthquakes. -equable nature of movements of subsidence and. -evidence in Scandinavia and Pampas of equable. -Hopkins on. -large areas simultaneously affected by. -d'Orbigny on sudden. -rate of. -Rogers on parallelism of cleavage and axes of. -sedimentary deposits exceptionally preserved during. -subsidence and. -vulcanicity and. Elodea canadensis, successful American immigrant. Emberiza longicauda, long tail-feathers and Sexual Selection. Embryology, argument for. -succession of changes in animal-. -Darwin's explanation of. -of flowers. -of Peneus. -Balfour's work on comparative. Embryonic stages, obliteration of. Endlicher's "Genera Plantarum." Engelmann, on variability of introduced plants in N. America. England, former union with Continent. -men of science of Continent and. Entada scandens, dispersal of seeds. Entomologists, evolutionary views of. "Entstehung und Begriff der naturhistorischen Art," Nageli's Essay. -Darwin on. Environment, and colour protection. Eocene, Anoplotherium in S. America. -monkeys. -mammals. -co-existence with recent shells. Eozoon, illustrating difficulty of distinguishing organic and inorganic bodies. Ephemera dimidiatum, Lord Avebury on. Epidendreae, closely related to Malaxeae. Epidendrum, Cruger on fertilisation of. -self-fertilisation of. Epiontology, De Candolle's term. Epipactis, fertilisation mechanism. -F. Muller on. -pollinia of. -E. palustris, fertilisation mechanism. Epithecia, fertilisation mechanism. Equatorial refrigeration. Equus, Marsh's work on. -geographical distribution. -in N. and S. America. Erica tetralix, Darwin on. Erigeron canadense, successful immigrant from America. Erodium cicutarium, introduced from Spain to America. -range in U.S.A. Erratic blocks, in Azores. -in S. America. -Darwin on transport. -of Jura. -Mackintosh on. -on Moel Tryfan. Errera, Prof. L., letter to. -and S. Gevaert, on cross and self-fertilisation. Eruptions, parallelism of lines of, with coast-lines. Eryngium maritimum, bloom on. Erythrina, MacArthur on. -of New S. Wales. -sleep movements of. Erythroxylon, dimorphism of sub-genus of. Eschscholtzia, crossing and self-fertility. -Darwin's experiments on self-sterility. -F. Muller's experiments in crossing. Eschricht, on lanugo on human embryo. Escombe, F., on vitality of seeds. -see Brown, H.T. Esquimaux, Natural Selection and. "Essays and Reviews," attitude of laymen towards. Eternity, Gapitche on. Etheridge, Robert, F.R.S.: President of Geological Society in 1880-81. Etna, Sir Charles Lyell's work on. -map of. Eucalyptus, species setting seed. -mentioned. Euonymus europaeus, dispersal of seeds. Euphorbia, Darwin on roots of. -E. peplis, bloom on. Euphrasia, parasitism of. Europe, movement of. Eurybia argophylla, musk-tree of Tasmania, an arborescent Composite. Evergreen vegetation, connection with humid and equable climate. Evolution, Darwin's early views. -Fossil Cephalopods used by Hyatt as test of. -Huxley's lectures on. -of mental traits. -F. Muller's contributions to. -Nageli's Essay, "Entstehung und Begriff der Naturhistorischen Art." -Palaeontology as illustrating. -Romanes' lecture on. -Saporta's belief in. -unknown law of. -of Angiosperms. -of colour. -and death. -Heer opposed to. -of language. -Lyell's views (see also Lyell). -Turner on man and. -Wallace on. Ewart, Prof. C., on Telegony. Exacum, dimorphism of. Experiments, botanical. -Tegetmeier's on pigeons. -time expended on. Expression, queries on. -Bell on anatomy of. -Darwin at work on. "Expression of the Emotions," Wallace's review. External conditions, Natural Selection and. -See also Direct Action. Extinction, behaviour of species verging towards. -contingencies concerned in. -Hooker on. -races of man and. -Proboscidea verging towards. -St. Helena and examples of. Eyebrows, use of. Eyes, behaviour during meditation. -contraction in blind people of muscles of. -children's habit of rubbing with knuckles. -gorged with blood during screaming. -contraction of iris. -wrinkling of children's. Fabre, J.H.: is best known for his "Souvenirs Entomologiques," in No. VI. of which he gives a wonderfully vivid account of his hardy and primitive life as a boy, and of his early struggles after a life of culture. -letters to. "Facts and Arguments for Darwin," translation of F. Muller's "Fur Darwin." -delay in publication. -sale. -unfavourable review in "Athenaeum." Fairy rings, Darwin compares with fungoid diseases in man and animals. Falconer, Hugh (1809-65): was a student at the Universities of Aberdeen and Edinburgh, and went out to India in 1830 as Assistant-Surgeon on the Bengal Establishment. In 1832 he succeeded Dr. Royle as the Superintendent of the Botanic Gardens at Saharunpur; and in 1848, after spending some years in England, he was appointed Superintendent of the Calcutta Botanical Garden and Professor of Botany in the Medical College. Although Falconer held an important botanical post for many years, he is chiefly known as a Palaeozoologist. He seems, however, to have had a share in introducing Cinchona into India. His discovery, in company with Colonel Sir Proby T. Cautley, of Miocene Mammalia in the Siwalik Hills, was at the time perhaps the greatest "find" which had been made. The fossils of the Siwalik Hills formed the subject of Falconer's most important book, "Fauna Antiqua Sivalensis," which, however, remained unfinished at the time of his death. Falconer also devoted himself to the investigation of the cave-fauna of England, and contributed important papers on fossils found in Sicily, Malta, and elsewhere. Dr. Falconer was a Vice-President of the Royal Society and Foreign Secretary of the Geological Society. "Falconer did enough during his lifetime to render his name as a palaeontologist immortal in science; but the work which he published was only a fraction of what he accomplished...He was cautious to a fault; he always feared to commit himself to an opinion until he was sure he was right, and he died in the prime of his life and in the fulness of his power." (Biographical sketch contributed by Charles Murchison to his edition of Hugh Falconer's "Palaeontological Memoirs and Notes," London, 1868; "Proc. R. Soc." Volume XV., page xiv., 1867: "Quart. Journ. Geol. Soc." Volume XXI., page xlv, 1865.) Hugh Falconer was among those who did not fully accept the views expressed in the "Origin of Species," but he could differ from Darwin without any bitterness. Two years before the book was published, Darwin wrote to Asa Gray: "The last time I saw my dear old friend Falconer he attacked me most vigorously, but quite kindly, and told me, 'You will do more harm than any ten naturalists will do good. I can see that you have already corrupted and half spoiled Hooker.'" ("Life and Letters," II., page 121.) The affectionate regard which Darwin felt for Falconer was shared by their common friend Hooker. The following extract of a letter from Hooker to Darwin (February 3rd, 1865) shows clearly the strong friendships which Falconer inspired: "Poor old Falconer! how my mind runs back to those happiest of all our days that I used to spend at Down twenty years ago--when I left your home with my heart in my mouth like a schoolboy. We last heard he was ill on Wednesday or Thursday, and sent daily to enquire, but the report was so good on Saturday that we sent no more, and on Monday night he died...What a mountainous mass of admirable and accurate information dies with our dear old friend! I shall miss him greatly, not only personally, but as a scientific man of unflinching and uncompromising integrity--and of great weight in Murchisonian and other counsels where ballast is sadly needed." -article in "Natural History Review." -Darwin's Copley medal and. -Darwin's criticism of his elephant work. -Darwin's regard for. -Forbes attacked by. -his opinion of Forbes. -goes to India. -Hooker's regard for. -letter to Darwin. -letter to Sharpey. -letters to. -letter to "Athenaeum." -Lyell and. -on Mastodon andium. -on Mastodon of Australia. -on elephants. -Owen and. -on phyllotaxis. -on Plagiaulax. -speech at Cambridge. -"Memoirs." Falkland Islands, Darwin visits. -Polyborus sp. in. -brightly coloured female hawk. -effect of subsidence. -streams of stones. Fanciers, use made of Selection by. Fantails, see Pigeons. Faraday, memorial to. Faramea, dimorphism. Farmer, Prof. J.B., and S.E. Chandler, on influence of excess of CO2 on anatomy of plants. Faroe Islands, Polygala vulgaris of. Farrer, Canon, lecture on defects in Public School Education. -letter to. Farrer, Lady. Farrer, Thomas Henry, Lord (1819-99): was educated at Eton and Balliol College, Oxford. He was called to the Bar, but gave up practice for the public service, where he became Permanent Secretary of the Board of Trade. According to the "Times," October 13th, 1899, "for nearly forty years he was synonymous with the Board in the opinion of all who were brought into close relation with it." He was made a baronet in 1883; he retired from his post a few years later, and was raised to the peerage in 1893. His friendship with Mr. Darwin was of many years' standing, and opportunities of meeting were more frequent in the last ten years of Mr. Darwin's life, owing to Lord Farrer's marriage with Miss Wedgwood, a niece of Mrs. Darwin's, and the subsequent marriage of his son Horace with Miss Farrer. His keen love of science is attested by the letters given in the present volume. He published several excellent papers on the fertilisation of flowers in the "Ann. and Mag. of Natural History," and in "Nature," between 1868 and 1874. In Politics he was a Radical--a strong supporter of free trade: on this last subject, as well as on bimetallism, he was frequently engaged in public controversy. He loyally carried out many changes in the legislature which, as an individualist, he would in his private capacity have strenuously opposed. In the "Speaker," October 21st, 1899, Lord Welby heads his article on Lord Farrer with a few words of personal appreciation:-- "In Lord Farrer has passed away a most interesting personality. A great civil servant; in his later years a public man of courage and lofty ideal; in private life a staunch friend, abounding as a companion in humour and ripe knowledge. Age had not dimmed the geniality of his disposition, or an intellect lively and eager as that of a boy--lovable above all in the transparent simplicity of his character." -interest in Torbitt's potato experiment. -letters to. -on earthworms. -observations on fertilisation of Passiflora. -recollections of Darwin. -seeds sent to. Fawcett, Henry (1833-84): Professor of Political Economy at Cambridge, 1863, Postmaster-General 1880-84. See Leslie Stephen's well-known "Life." -defends Darwin's arguments. -letter to. -letter to Darwin. Fear, expression of. Felis, range. Fellowships, discussion on abolition of Prize-. Felspar, segregation of. Females, modification for protection. "Fenland, Past and Present," by Miller and Skertchley. Fergusson on Darwinism. Fernando Po, plants of. Ferns, Scott on spores. -Darwin's ignorance of. -variability "passes all bounds." Ferrier, Dr., groundless charge brought against, for infringement of Vivisection Act. Fertilisation, articles in "Gardeners' Chronicle." -of flowers. -H. Muller's work on. -and sterility. -Darwin fascinated by study of. -different mechanisms in same genus. -travelling of reproductive cells in. Fertilisation of orchids, Darwin's work on. -paper by Darwin in "Gardeners' Chronicle" on. "Fertilisation of Orchids," Asa Gray's review. -Hooker's review. -description of Acropera and Catasetum in. -H. Muller's "Befruchtung der Blumen," the outcome of Darwin's. Fertility, Natural Selection and. -and sterility. -Primula. -Scott on varieties and relative. Festuca. Figs, F. Muller on fertilisation of. Finmark, Bravais on sea-beaches of. Fir (Silver), Witches' brooms of. "First Principles," Spencer's. Fish, Pictet and Humbert on fossil. Fiske, J., letter to. Fissure-eruptions. Fitton, reference to his work. FitzRoy (Fitz-Roy), Captain, and the "Beagle" voyage. -writes preface to account of the voyage. -Darwin nearly rejected by. -letter to "Times." Flagellaria, as a climber. Flahault, on the peg in Cucurbita. Fleeming Jenkin, review of "Origin" by, see Jenkin. Flinders, M., voyage to Terra Australis by. Flint implements found near Bedford. Flints, abundance and derivation of, at Down. -Darwin on their upright position in gravel. Floating ice, Darwin on agency of. -J. Geikie underestimates its importance. -transporting power of. Flora, Darwin's idea of an Utopian. -Hooker's scheme for a. -Hooker's work on Tasmanian. "Flora antarctica," Hooker's. "Flora fossilis arctica," Heer's. Floras: N. American. Arctic. British. Colonial. European. French. Greenland. Holland. India. Japan. New Zealand. -distribution of. -of islands. -local. -tabulation of. Florida, A. Agassiz on Coral reefs. -Coral reefs. Flourens, experiments on pigeons. Flower, Sir William H., Letter to. -on muscles of the os coccyx. Flowering plants, possible origin on a Southern Continent. -sudden appearance of. Flowers, at Down. -Darwin's work on forms of. -monstrous. -morphological characters. -regular and irregular. -cross-fertilisation in inconspicuous. -ignorance of botanists on mechanism of. "Flowers and their unbidden Guests," Dr. Ogle's translation of Kerner's "Schutzmittel des Pollens." Flying machine, Darwin on Popper's proposed. Folding of strata. Foliation and cleavage, reference by A. Harker to work on. Foliation, aqueous deposition and. -Darwin considers his observations on cleavage less deserving of confidence than those on. -Darwin on. -parallelism with cleavage. -relation to rock-curvature. Food, as determining number of species. Foraminifera. Forbes, D., on the Cordilleras. -on elevation in Chili. -on nitrate of soda beds in S. America. Forbes, Edward, F.R.S. (1815-1854): filled the office of Palaeontologist to the Ordnance Geological Survey, and afterwards became President of the Geological Society; in 1854--the last year of his life--he was appointed to the chair of Natural History in the University of Edinburgh. Forbes published many papers on geological, zoological, and botanical subjects, one of his most remarkable contributions being the well-known essay "On the Connexion between the Distribution of the Existing Fauna and Flora of the British Isles and the Geological Changes which have affected their area" ("Mem. Geol. Surv." Volume I., page 336, 1846). (See "Proc. Roy. Soc." Volume VII., page 263, 1856; "Quart. Journl. Geol. Soc." Volume XI., page xxvii, 1855, and "Ann. Mag. Nat. Hist." Volume XV., 1855. -on flora of Azores. -on Chambers as author of the "Vestiges." -on continental extension. -Darwin opposed to his views on continental extension. -Darwin's opinion of. -Article on distribution. -on continuity of land. -on plant-distribution. -introductory lecture as professor in Edinburgh. -on former lower extension of glaciers in Cordillera. -lecture by. -letter to Darwin from. -on Madagascar insects. -on post-Miocene land. -Polarity theory. -on British shells. -too speculative. -on subsidence. -visits Down. -mentioned. -royal medal awarded to. -essay on connection between distribution of existing fauna and flora of the British Isles and geological changes. Forbes, H.O., on Melastoma. Force and Matter, Huxley on. Forel, Auguste: the distinguished author of "Les Fourmis de la Suisse," Zurich, 1874, and of a long series of well-known papers. -on ants and beetles. -author of "Les Fourmis de la Suisse." -letter to. Forfarshire, Lyell on glaciers of. "Forms of Flowers," De Candolle's criticism of Darwin's. homomorphic and heteromorphic unions described in. Forsyth-Major, zoological expedition to Madagascar. "Fortnightly Review," Huxley's article on Positivism. Romanes on Evolution. Fossil Cephalopods, Hyatt on. Fossil corals. Fossil plants, small proportion of. of Australia. sudden appearance of Angiosperms indicated by. Fossil seeds, supposed vivification of. Fossils as evidence of variability. Fournier, E., De la Fecundation dans les Phanerogames. Fowls, difference in sexes. -purred female. Fox, tails of, used by Esquimaux as respirators. Fox, Rev. W. Darwin. Foxglove, use of hairs in flower. France, edition of "Origin" in. -opinion favourable to Darwin's views in. -birth-rate. Franco-Prussian war, opinion in England. -Science retarded by. Frank, Albert Bernhard (1839-1900): began his botanical career as Curator of the University Herbarium, Leipzig, where he afterwards became Privatdocent and finally "Ausserordentlicher Professor." In 1881 Frank was appointed Professor of Plant-Physiology in the Landwirthschaftliche Hochschule, Berlin. In 1899 he was appointed to the Imperial Gesundheits-Amt in Berlin, and raised to the rank of Regierungsrath. Frank is chiefly known for his work on "The Assimilation of Free Nitrogen, etc.," and for his work on "The Diseases of Plants" ("Die Krankheiten der Pflanzen," 1880). It was his brilliant researches on growth-curvature ("Beitrage zur Pflanzen-physiologie," 1868, and "Die Naturlichen wagerechte Richtung von Pflanzen-theilen," 1870) which excited Darwin's admiration. -Darwin's admiration for his work. Franklin, Sir J., search expedition. Fraser, G., letter to. "Fraser's Magazine," article by Hopkins. -article by Galton on twins. -Huxley on review in. Freemasons' Tavern, meeting held at. Freewill, a preordained necessity. Freke, Dr., paper by. Freshwater, Bee-orchis at. Freshwater fauna, ocean faunas compared with. -poverty of. -preservation of. Friendly Islands, rats regarded as game. Fringillidae, colour and sexual selection. Frogs, article on spawn of. -F. Muller on. -salt water and spawn of. -frozen in glaciers. Fruits, bright colours of. Fucus, variation in. Fuegia, plants of, (see also Tierra del Fuego). Fumaria (Corydalis) claviculata, Mohl on tendrils. Fumariaceae, cross- and self-fertilisation. -morphology of tendrils. Funafuti, Darwin's theory supported by results of boring in coral island of. Fungoid diseases, Darwin on. Fungus, effect on roots and shoots. "Fur Darwin," F. Muller's (see "Facts and Arguments for Darwin). -Darwin quotes. -Hooker's opinion of. -publication of. Furze, seeds and seedlings. Galapagos Islands, visited during the "Beagle" voyage. -birds of. -character of species of, the beginning of Darwin's evolutionary views. -distribution of animals. -distribution of plants. -flora of. -Hooker on plants of. -insects. -craters. -fissure eruptions in. -restricted fauna. -Sandwich Islands and. -subsidence in the. Galashiels, terraces near. Galaxias, distribution of. Gallinaceae, Blyth on. -colour of. Galls, artificial production of. -Cynips and. -hybrids and. -Walsh on willow-. Gallus bankiva, colour of wings. -colour and environment. -wings of. Galton, F., experiments on transfusion of blood. -letters to. -letter to Darwin from. -on twins. -on variation. -on heredity. -on human faculty and its development. -on prayer. -proposal to issue health certificates for marriage. Game-cock and Sexual Selection. Gamlingay, lilies-of-the-valley at. Ganoid fishes, preservation in fresh water. Gapitche, A., letter to. "Gardeners' Chronicle," Darwin's article on fertilisation. -Darwin's opinion of. -Darwin's experiment on immersion of seeds in salt water. -article on Orchids. -Harvey on Darwin. -Rivers' articles. -Wallace on nests. -Darwin's index. Gardner, G., "Travels in the Interior of Brazil." Gartner, on Aquilegia. -experiments on crossing and variation. -on Primula. -on Verbascum. -Darwin's high opinion of his "Bastarderzeugung." -Beaton's criticism of. -on self-fertilisation in flowers. -mentioned. Gaskell, G.A., Letter to. Gatke, on "Heligoland as an Ornithological Observatory." Gaudry, Albert: Professor of Palaeontology in the Natural History Museum, Paris, Foreign Member of the Royal Society of London, author of "Animaux Foss. et Geol. de l'Attique." -letter to. -on Pikermi fossils. Gay, on lizards. Gazania. Gegenbauer, Karl: Professor of Anatomy at Heidelberg. -as convert to Darwinism. -views on regeneration. Geikie, Sir A., on age of the Earth. -edition of "Hutton's Theory of the Earth." -memoir of Sir A.C. Ramsay. Geikie, Prof. J., "Ice Age." -on intercrossing of erratics. -Letters to. -"Prehistoric Europe." -Presidential address, Edinburgh British Association meeting. Geitonogamy, Kerner suggests term. Gemmation and dimorphism. Gemmules, in reproductive organs. -and bud-variation. Genealogy and classification. Genera, aberrant. -range of large and small. -variation of. -Wallace on origin of. "Genera Plantarum," work on the. Generalisations, evil of. -easier than careful observation. -importance. "Generelle Morphologie," Darwin on Hackel's. "Genesis of Species," Mivart's Geographical distribution, L. Agassiz on. -Darwin on. -Darwin's high opinion of value of. -Darwin's interest in. -E. Forbes on. -Huxley on birds and. -proposed work by Hooker on. -relation of genera an important element in. -Humboldt the founder of. "Geographical Distribution of Animals," Darwin's criticism of Wallace's. "Geographical Distribution of Mammals," A. Murray's. Geographical regions, Darwin on. Geological Committee on the Parallel Roads of Glen Roy. "Geological Gossip," Ansted's. "Geological Instructions," Darwin's manual of. "Geological Observations in S. America," Darwin's. -Darwin on his. Geological record, imperfection of the. -Morse on the. Geological Society, award of medal to Darwin. -Darwin signs Hooker's certificate. -museum of. -Darwin attends Council meeting. Geological Survey, foundation of. -investigation of the Parallel Roads of Glen Roy. Geological Time, article in "N. British Review." Geologist, Darwin as. Geologists, evolutionary views of. Geology, arguments in favour of evolution from. -chapter in "Origin" on. -practical teaching of. -English work in. -Hooker talks of giving up. -Lyellian school. -progress of. Geotropism, Darwin on. German, Darwin's slight knowledge of. Germany, converts to evolution in. -opinion on the "Origin" in. -Englishmen rejoice over victory of. Germination of seeds, Darwin's experiments on effect of salt water. "Germs and Vestiges of Disease," Dobell's. Gesneria, Darwin on dimorphism of. Gestation of hounds. Gibraltar, elevation and subsidence of. Gilbert, Sir J.H.: of Rothamsted. -letter to. -on nitrogen in worms' casting. -and Sir J. Lawes, Rothamsted experiments. Glacial period, absence of phanerogams near polar regions in N. America during. -Bates on. -climatic changes since. -conditions during. -continental changes since. -Darwin's views on geographical changes as cause of. -destruction of organisms during. -destruction of Spanish plants in Ireland. -distribution of organisms affected by. -duration of. -effect on animals and plants. -and elephants. -S.E. England dry land during. -Greenland depopulated during. -introduction of Old World forms into New World subsequent to. -migration during. -mundane character of. -subsidence of Alps during. -Croll on. -existence of Alpine plants before. -Hooker on. -Glen Roy and. -Lyell on. -extinction of mammals during. -Wallace on. -movement of Europe since and during. Glaciers, Agassiz on. -Lyell on. -Tyndall's book on. -as agents in the formation of lakes. -Darwin on structure of. -Hooker on Yorkshire. -Moseley on motion of. -physics of. -Parallel Roads of Glen Roy formed by. -rock-cavities formed by cascades in. -in S. America. -in Wales. Gladstone, Herbert Spencer on criticisms by. Glass, Dr., on grafting sugar-canes. Glen Collarig, absence of terminal moraines. -terraces in. Glen Glaster, absence of terminal moraines. -barriers of detritus. -Milne on. -shelves of. Glen Gluoy, shelves of. Glen Roy, Parallel Roads of. -L. Agassiz on. -Darwin on. -Darwin's mistake over. -Darwin on ice-lake theory of Agassiz and Buckland. -glacier theory of. -history of work on. -Hooker on. -marine theory of. -Milne-Home's paper on. -investigated by Geological Survey. -coincidence of shelves with watersheds. -measurement of terraces. Glen Spean. Glen Turret, MacCulloch on. Gloriosa, Darwin's experiments on leaf-tendrils. Glossotherium Listai. Gloxinia, peloric forms of. Gnaphalium. Gneiss, Darwin on. God, Darwin on existence of personal. Godron, on Aegilops. Godron's "Flora of France." Goethe, Darwin's reference to. -Owen on. Goldfinch, difference in beaks of male and female. Gongora, and Acropera. -Darwin on. -G. fusca (see Acropera luteola). -G. galeata (see A. Loddigesii). Gondwana Land. Goodenia, Hamilton on fertilisation of. Goodeniaceae. Gordon, General, Huxley on Darwin and. Gosse, E., "Life of P.H. Gosse" by. Gosse, Philip Henry (1810-88): was an example of that almost extinct type-- a naturalist with a wide knowledge gained at first hand from nature as a whole. This width of culture was combined with a severe and narrow religious creed, and though, as Edmund Gosse points out, there was in his father's case no reconcilement of science and religion, since his "impressions of nature" had to give way absolutely to his "convictions of religion," yet he was not debarred by his views from a friendly intercourse with Darwin. He did much to spread a love of Natural History, more especially by his seaside books, and by his introduction of the aquarium-- the popularity of which (as Mr. Edmund Gosse shows) is reflected in the pages of "Punch," especially in John Leech's illustrations. Kingsley said of him (quoted by Edmund Gosse, page 344) "Since White's "History of Selborne" few or no writers on Natural History, save Mr. Gosse and poor Mr. Edward Forbes, have had the power of bringing out the human side of science, and giving to seemingly dry disquisitions...that living and personal interest, to bestow which is generally the special function of the poet." Among his books are the "Naturalist's Sojourn in Jamaica," 1851; "A Naturalist's Rambles on the Devonshire Coast," 1853; "Omphalos," 1857; "A Year at the Shore," 1865. He was also author of a long series of papers in scientific journals. -letter to. Gould, on sex in nightingales. Gower Street, Darwin's house in. Gradation in plants. Graft-hybrids, experiments on. -of Cytisus. -Hildebrand on. -of potatoes. -of sugar-canes. Grafting, Darwin on. -difficulty of. -in hyacinth bulbs. Graham's "Creed of Science." Gramineae, Darwin on crossing. Granite, explanation of association with basalt. Grasses, range of genera. -cleistogamous. -fertilisation of. -F. Muller on Brazilian. Gratiolet, on behaviour of eyes in rage. Gravity, comparison between variation and laws of. Gray, Asa (1810-88): was born in the township of Paris, Oneida Co., New York. He became interested in science when a student at the Fairfield Academy; he took his doctor's degree in 1831, but instead of pursuing medical work he accepted the post of Instructor in Chemistry, Mineralogy, and Botany in the High School of Utica. Gray afterwards became assistant to Professor Torrey in the New York Medical School, and in 1835 he was appointed Curator and Librarian of the New York Lyceum of Natural History. From 1842 to 1872 he occupied the Chair of Natural History in Harvard College, and the post of Director of the Cambridge Botanical Gardens; from 1872 till the time of his death he was relieved of the duties of teaching and of the active direction of the Gardens, but retained the Herbarium. Professor Gray was a Foreign Member of the Linnean and of the Royal Societies. The "Flora of North America" (of which the first parts appeared in 1838), "Manual of the Botany of the Northern United States, the Botany of Commodore Wilkes' South Pacific Exploring Expedition" are among the most important of Gray's systematic memoirs; in addition to these he wrote several botanical text-books and a great number of papers of first-class importance. In an obituary notice written by Sir Joseph Hooker, Asa Gray is described as "one of the first to accept and defend the doctrine of Natural Selection..., so that Darwin, whilst fully recognising the different standpoints from which he and Gray took their departures, and their divergence of opinion on important points, nevertheless regarded him as the naturalist who had most thoroughly gauged the "Origin of Species," and as a tower of strength to himself and his cause" ("Proc. R. Soc." Volume XLVI., page xv, 1890: "Letters of Asa Gray," edited by Jane Loring Gray, 2 volumes, Boston, U.S., 1893). -articles by. -as advocate of Darwin's views. -Darwin's opinion of. -on Hooker's Antarctic paper. -on large genera varying. -letters to Darwin from. -letters to. -on Darwin's views. -plants of the Northern States. -on variation. -book for children by. -on crossing. -visits Down. -on dimorphism. -on Agassiz. -extract from letter to G.F. Wright from. -on fertilisation of Cypripedium. -on Gymnadenia tridentata. -on Habenaria. -on Passiflora. -on relative ranges of U. States and European species. -on Sarracenia. -mentioned. Gray, Mrs. Gray, Dr. John Edward, F.R.S. (1800-75): became an assistant to the Natural History Department of the British Museum in 1824, and was appointed Keeper in 1840. Dr. Gray published a great mass of zoological work, and devoted himself "with unflagging energy to the development of the collections under his charge." ("Ann. Mag. Nat. Hist." Volume XV., page 281, 1875.) -and British Museum. Greatest Happiness principle. Grebes, as seed-eaters. Greenland, absence of Arctic Leguminosae. -connection with Norway. -flora of. -introduction of plants by currents. -as line of communication of alpine plants. -migration of European birds to. Greg, W.R.: Author of "The Enigmas of Life," 1872. -Darwin on his "Enigmas of Life." -letter to. Grey, Sir G., on Australian Savages. Grinnell expedition, reference to the second. Grisebach, A. Grisebach, A.W. Grossulariaceae. Grouse, Natural Selection and colours of. -Owen describes as distinct creation. Grypotherium Darwini. -G. domesticum. Guiana, Bates on. Gulf-weed, Darwin on. Gully Dr. Gunther, Dr., visit to Down. Gurney, E., articles in "Fortnightly" and "Cornhill." -"Power of Sound." Gymnadenia, course of vessels in flower of. -Asa Gray on. -penetration by pollen of rostellum. Gynodioecism in Plantago. Haast, Sir Julius von, (1824-87): published several papers on the Geology of New Zealand, with special reference to glacial phenomena. ("Quart. Journ. Geol. Soc." Volume XXI., pages 130, 133, 1865; Volume XXIII., page 342, 1867.) -on glacial deposits. Habenaria, Azorean species (see also Peristylus viridis). -course of vessels in flower. -Lord Farrer on. -morphology of flower. -H. bifolia, flowers. -a subspecies of H. chlorantha. -H. chlorantha, considered by Bentham a var. of H. bifolia. -structure of ovary. Hackel, E., convert to Darwin's views. -"Generelle Morphologie." -Die Kalkschwamme. -"Freedom in Science and Teaching." -letters to. -on pangenesis. -proposed translation of his book. -on reviews of "Origin" in Germany. -on sponges. -substitutes a molecular hypothesis for pangenesis. -visits Down. -on absence of colour-protection in lower animals. -on change of species. -on Linope. -on medusae. Haematoxylon, bloom-experiments on. -sleep-movements. Halictus, Fabre's paper on. Halimeda, Darwin's description of. Halleria, woody nature of. Hallett, on varieties of wheat. Hamilton, on fertilisation of Dampiera. Hamilton, Sir W., on Law of Parsimony. Hancock, Albany (1806-73): author of many zoological and palaeontological papers. His best-known work, written in conjunction with Joshua Alder, and published by the Ray Society is on the British Nudibranchiate Mollusca. The Royal Medal was awarded to him in 1858. -on British shells. -and Royal medal. Hanley, Dr., Darwin's visit to. Harker, A., note on Darwin's work on cleavage and foliation. Hartman, Dr., on Cicada septendecim. "Harvesting Ants and Trap-door Spiders," Moggridge's. Harvey, William Henry (1811-66): was the author of several botanical works, principally on Algae; he held the botanical Professorship at Trinity College, Dublin, and in 1857 succeeded Professor Allman in the Chair of Botany in Dublin University. (See "Life and Letters," II., pages 274-75.) -criticism of "Origin." -Darwin's opinion of his book. -letter to. -mentioned. -on variation in Fucus. Haughton, Samuel (1821-97): author of "Animal Mechanics, a Manual of Geology," and numerous papers on Physics, Mathematics, Geology, etc. In November 1862 Darwin wrote to Sir J.D. Hooker: "Do you know whether there are two Rev. Prof. Haughtons at Dublin? One of this name has made a splendid medical discovery of nicotine counteracting strychnine and tetanus? Can it be my dear friend? If so, he is at full liberty for the future to sneer [at] and abuse me to his heart's content." Unfortunately, Prof. Haughtons' discovery has not proved of more permanent value than his criticism on the "Origin of Species." -on Bees' cells. -on depth of ocean. -review by. -mentioned. Hawaiian Islands, Hillebrand's Flora. -plants. Hawks and owls as agents in seed-dispersal. -bright colours in female. Head, expression in movement of. Hearne, on black bear. Heat, action on rocks. Heathcote, Miss. Heaths, as examples of boreal plants in Azores. -and climate. Heberden, Dr., mentioned. Hector. Hedgehog, movements of spines. Hedychium, Darwin's prediction as to fertilisation of. -paraheliotropism. Hedyotis, dimorphism of. Hedysarum, Darwin's experiments on (see Desmodium gyrans). Heer, Oswald (1809-83): was born at Niederutzwyl, in the Canton of St. Gall, Switzerland, and for many years (1855-82) occupied the chair of Botany in the University of Zurich. While eminent as an entomologist Heer is chiefly known as a writer on Fossil Plants. He began to write on palaeobotanical subjects in 1841; among his most important publications, apart from the numerous papers contributed to scientific societies, the following may be mentioned: "Flora Tertiaria Helvetiae," 1855-59; the "Flora Fossilis Arctica," 7 volumes, 1869-83; "Die Urwelt der Schweiz," 1865; "Flora Fossilis Helvetiae," 1876-7. He was awarded the Wollaston medal of the Geological Society in 1874, and in 1878 he received a Royal medal. (Oswald Heer, "Bibliographie et Tables Iconographiques," par G. Malloizel, precede d'une Notice Biographique" par R. Zeiller; Stockholm.) -on continental extension. -on plants of Madeira. -on origin of species from monstrosities. -Darwin sends photograph to. -"Flora fossilis arctica." -letter to. Heeria (see also Heterocentron). -F. Muller on. Heifers, and sterility. Helianthemum, Baillon's observations on pollen. Heligoland, birds alight on sea near. Heliotropism, experiments on. -of roots. Hemsley, W.B., mentioned. Hennessey. Henry, I.A. (see Anderson-Henry) -letter to. Henslow, Prof. J.S., life of. -Darwin's affection for. -Darwin's Cambridge recollections of. -death of. -letters to. -mentioned. -on Mus messorius. -visits Down. -Darwin on his parish work. -work on crossing. Henslow, Miss, mentioned. Herbaceous orders, in relation to trees. Herbert, Dean, on heaths of S. Africa. -on Polygala. -on Cytisus Adami. -on self-fertility of Hippeastrum. -mentioned. "Hereditary Genius," Francis Galton's. Hereditary Improvement, Francis Galton on. Heredity, Darwin's criticism of Galton's theory. Hermaphroditism, in trees. -Weir on Lepidoptera and. -and nature of generative organs. Herminium monorchis. Heron, Sir R., on peacocks and colour. Herons, as fruit-feeders. Herschel, Sir J.F.W., edits "Manual of Scientific Enquiry." -on Natural Selection. -on the "Origin." -"Physical Geography." -on providential laws. -on heating of rocks. -on importance of generalising. -on study of languages. -versus Lyell on volcanic islands. -mentioned. Heteranthera, two kinds of stamens. -H. reniformis. Heterocentron, experiments on. -seeds of. -two kinds of stamens. -H. roseum, fertilisation mechanism of. Heterogeny, Owen on. Heteromorphic, use of term. Heterosmilax, de Candolle on. Heterostylism, Darwin's experiments on. -example in monocotyledons of. Hewitt, on pheasant-hybrids. -mentioned. Hibiscus. Hicks, H., on pre-Cambrian rocks. Hieracium, American species. -Nageli on. -variability of. Highness, lowness and. Hilaire, A. St., see St. Hilaire. Hildebrand, F., article in "Botanische Zeitung." -experiments on direct action of pollen. -"Die Lebensdauer der Pflanzen." -letter to. -crossing work by. -on Delpino's work. -on dispersal of seeds. -self-sterility in Corydalis cava. -"Geschlechter-Vertheilung bei den Pflanzen." -on orchids. -on ovules formed after pollination. -experiment on potatoes. -on Salvia. -mentioned. Hilgendorf, controversy with Sandberger. Hillebrand's Flora of the Hawaiian Islands. "Himalayan Journals," dedicated by Hooker to Darwin. "Himalayan Plants, Illustrations of." Himalayas, British plants in. -commingling of temperate and tropical plants. -tortoise of. -ice-action in. -mixed character of the vegetation. Hinde, Dr., examination of Funafuti coral-reef cores by. Hindmarsh, L., letter to. Hippeastrum, Herbert on self-sterility of. Hippopotamus, fossil in Madagascar. Historic spirit, J. Morley's criticism of Darwin's lack of. Hitcham, collection of Azorean plants made near. Hobhouse, Sir A., Darwin meets. Hochberg, K., letter to. Hofmann, A.W., receives royal medal. Holland, evolutionary opinions in. -flora of. Holland, Sir H., on pangenesis. -mentioned. -on influence of mind on circulation. Holly, effective work of insects in fertilisation of. Hollyhock, Darwin's crossing experiments. Holmsdale. Home, see Milne-Home. Homing experiments. Homo, Pithecus compared with. Homology, analogy and. -course of vessels in flowers as guide to. Homomorphic, use of term. Honeysuckle, oak-leaved variety. Hooker, Mrs., assists Sir J.D. Hooker. Hooker, Sir J.D., addresses at British Association meetings. -on Arctic plants. -Australian Flora by. -botanical appointment. -C.B. conferred upon. -on coal plants and conditions of growth. -criticism on Lyell's work. -on Darwin's MS. on geographical distribution. -Darwin's admiration for letters of. -Darwin assisted in his work by. -Darwin on good gained by "squabbles" with. -Darwin on success of. -enjoyment of correspondence with Darwin. -expedition to Syria. -extract from letter to. -Falconer and. -first meeting with Darwin. -on Insular Floras. -introductory essay to Flora of Tasmania. -lecture at Royal Institution. -letters to. -letters to Darwin from. -on new colonial flora. -on New Zealand flora. -on Natural Selection. -on naturalised plants. -on the "Origin." -and Owen. -on pangenesis. -on plants of Fernando Po and Abyssinia. -on preservation of tropical plants during cool period. -and reviews. -royal medal awarded to. -and J. Scott. -on species. -on Torbitt's potato experiments. -on use of terms centripetal and centrifugal. -on variation in large and small genera. -on Welwitschia. -on Cameroon plants. -Darwin on his address at Belfast. -Darwin writes testimonial for. -Darwin values scientific opinion of. -Darwin receives encouragement from. -Darwin's pleasure at visits from. -on Glacial period. -on Glacial deposits in India. -on glaciers in Yorkshire. -notice in "Gardeners' Chronicle" on. -photograph by Mrs. Cameron. -Primer of Botany by. -review of Darwin's "Fertilisation of Orchids." -scheme for Flora. -represents "whole great public" to Darwin. -use of structure in plants. -visits Down. -opinion of "Fur Darwin." -mentioned. Hooker, Sir William Jackson (1785-1865): was called to the Chair of Botany at Glasgow in 1820, where by his success as a teacher he raised the annual fees from 60 pounds to 700 pounds. In 1841 he became Director of the Royal Botanic Gardens at Kew, which under his administration increased enormously in activity and importance. His private Herbarium, said to be "by far the richest ever accumulated in one man's lifetime," formed the nucleus of the present collection. He produced, as author or editor, about a hundred volumes devoted to Botany ("Dict. of Nat. Biog."). -Herbarium at Kew belonging to. -letters to. -mentioned. Hopkins, William, F.R.S. (1793-1866) entered Peterhouse, Cambridge, at the age of thirty, and in 1827 took his degree as seventh wrangler. For some years Hopkins was very successful as a mathematical tutor; about 1833 he began to take a keen interest in geological subjects, and especially concerned himself with the effects of elevating forces acting from below on the earth's crust. He was President of the Geological Society in 1851 and 1852 ("Quart. Journ. Geol. Soc." Volume XXIII., page xxix, 1867). -Article in "Fraser's Magazine." -on elevation and earthquakes. -on mountain-building. -researches in physical geology. -mentioned. Horner, Leonard, F.R.S. (1785-1862): was born in Edinburgh, at the age of twenty-one he settled in London, and devoted himself more particularly to Geology and Mineralogy, returning a few years later to Edinburgh, where he took a prominent part in founding the School of Art and other educational institutions. In 1827 Mr. Horner was invited to occupy the post of Warden in the London University,a position which he resigned in 1831; he also held for some years an Inspectorship of Factories. As a Fellow of the Royal Society, Mr. Horner "took an active part in bringing about certain changes in the management of the Society, which resulted in limiting to fifteen the number of new members to be annually elected..." In 1846 Horner was elected President of the Geological Society; and in 1860 he again presided over the Society, to the interests of which he had long devoted himself. His contributions to the Society include papers on Stratigraphical Geology, Mineralogy, and other subjects.--"Memoirs of Leonard Horner," edited by his daughter, Katherine M. Lyell (privately printed, 1890). -letters to. -memoirs of. -address to Geological Society. -on coal. -on Darwin's "Geological Observations." -visits Down. -mentioned. Horner, Mrs. L. Horse, ancestry. -Arab-Turk and English race-. -hybrids between Quagga and. -in N. and S. America. -equality of sexes in race-. Horsfall, W., letter to. Hottonia, dimorphism of. Hounds, gestation of. Howard, L.O. Hoya carnosa, Darwin's work on. Humble-bees, as agents of fertilisation of orchids. Humboldt, Bates' description of tropical forests compared with that by. -conversation with. -on heath regions. -on migration and double creation. -"Personal Narrative." -on violet of Teneriffe. -Darwin's opinion of. -on elevation and volcanic activity. -mentioned. Humboldt and Webb, on Zones on Teneriffe. Hume, Darwin on Huxley's "Life" of. Humming-birds, agents of fertilisation. Hunger, expression by sheldrakes of. Husbands, resemblance between wives and. Hutton, Frederick Wollaston, F.R.S., formerly Curator of the Canterbury Museum, Christchurch, New Zealand, author of "Darwinism and Lamarckism, Old and New," London, 1899. -letter to. -review of "Origin." Hutton, James, (1726-97): author of "Theory of the Earth." Huxley, L., reference to his "Life of T.H. Huxley." -information given by. Huxley, Prof. T.H., biographical note, Volume I. -Article in "Annals and Magazine" in reply to Falconer. -on Aphis. -on automatism. -catalogue of collections in Museum of Practical Geology. -comparative anatomy by. -on Comte. -on Cuvier's classification. -Darwin's value of his opinion. -election to the Athenaeum. -friendship with Darwin. -on growth of Darwin's views. -lectures at the Royal Institution. -lectures on evolution by. -lectures to working men. -legacy and gift to. -letters to. -"Life of Hume." -"Man's Place in Nature." -marriage. -misrepresented by Owen. -founds "Natural History Review." -obituary notice of Darwin. -on the "Origin of Species." -on Owen's archetype book. -president of the British Association meeting at Liverpool (1870). -on Priestley. -quoted by Lord Kelvin as an unbeliever in spontaneous generation. -reviews by. -review of "Vestiges of Creation" by. -on Sabine's address. -on saltus. -prefatory note to Hackel's "Freedom in Science and Teaching." -address to Geological Society (1869). -on classification of man. -on contemporaneity. -on Catasetum. -on deep-sea soundings. -legacy from A. Rich. -on Lyell's "Principles." -on use of term physiological species. -on vivisection. -and H.N. Martin, "Elementary Biology" by. -mentioned. Huxley, Mrs. T.H., queries on expression sent by Darwin to. -observations on child crying. -mentioned. Hyacinth, experiment on bulbs. Hyatt, Alpheus (1838-1902): was a student under Louis Agassiz, to whose Laboratory he returned after serving in the Civil War, and under whom he began the researches on Fossil Cephalopods for which he is so widely known. In 1867 he became one of the Curators of the Essex Institute of Salem, Mass. In 1870 he was made Custodian, and in 1881 Curator of the Boston Society of Natural History. He held professorial chairs in Boston University and in the Massachusetts Institute of Technology, and "was at one time or another officially connected with the Museum of Comparative Zoology and the United States Geological Survey." See Mr. S. Henshaw ("Science," XV., page 300, February 1902), where a sketch of Mr. Hyatt's estimable personal character is given. See also Prof. Dall in the "Popular Science Monthly," February 1902. -and Hilgendorf. -letters to. -letters to Darwin from. -on tetrabranchiata. Hyatt and Cope, theories of. Hybridism, chapter in "Origin" on. -Bentham's address on. -treatment by Darwin in "Variation of Animals and Plants." Hybrids, and adaptation. -Darwin's views on. -evidence in favour of pangenesis from. -experiments on. -fertility of. -intermediate character of. -primrose and cowslip. -article in "Quarterly Review" on. -sterility of. -Max Wichura on. -Bronn on. -F. Muller's work on. -and heterostyled plants. -rarity of natural. -J. Scott's work on. -tendency to reversion. Hydra, sexuality of. Hydropathy, Darwin and. Hydrozoa, alternation of generations in. Hymenoptera, affinities of. -H. Muller on. Hypericum perforatum, a social plant in U.S.A. Hyracotherium cuniculus, Owen on. Iberis, mucus in seeds of. Ice, as agent in dispersal of boulders. -agent in dispersal of plants. -Forbes on transport by. -agent in lake-formation. -cleavage in. -work of, a new factor in geology. Ice-action, on land and sea. Icebergs, as factor in explaining European plants in Azores. -Croll on action of. -Darwin on. -evidence in S. America of. -Hopkins on action of. Ice-cap, of Arctic regions. Iceland, importance of records of volcanic phenomena in. Ignorance, Darwin on immensity of man's. Ilkley, Darwin's visit to. Illegitimate offspring, need for repetition of Darwin's experiments on plants'. Imatophyllum. Immortality, Darwin on. Immutability of species. -Falconer disbelieves in. -Darwin on. Imperfection of the Geological Record, see Geological Record. Impotence in plants. -see also Self-sterility. India, British rule in. -flora of. -Hooker in. -varieties of domestic animals in. -H.F. Blanford on. -Darwin on origin of lakes in. -evidence of colder climate in. -J. Scott accepts post in. Infants, Mrs. E Talbot on development of mind in. -observations on ears of. Infusoria, possible occurrence in underclays of coal. Inglis, Sir R., Darwin at breakfast party. Inheritance, atavism and. -conservative tendency of long. -Hackel on. -hypothesis on. -Jager on. -and Natural Selection. -power of. -J.C. Prichard on. -and variability. -Darwin on. -Galton on. Insanity, concealment of. "Insect Life," Howard's. Insectivorous plants, Darwin's work on. Insects, alpine. -Lord Avebury on. -Bates on. -fossil. -luminous. -of Madeira. -F. Muller on metamorphosis of. -Sharp's book on. -study of habits more valuable than description of new species. -wingless. -Wollaston on. -antiquity of stridulating organs in. -colour and Sexual Selection. -H. Muller's work on adaptation to fertilisation of flowers. -metamorphosis of. -music as attraction to. -observation on fertilisation of flowers by. -Ramsay on. -Riley's work on. -tropical climate and colours of. Instinct, Darwin and. -in nest-making. -selection of varying. Insular floras. -Hooker's lecture on. Insular forms, in Galapagos, Canaries and Madeira. -beaten by continental forms. Intelligence, meaning of. -Romanes on Animal. -in worms. Intercrossing, in pigeons. -Darwin on effects of. -and sterility. Interglacial periods, Darwin on evidence for. Intermediate forms. -Bates' paper on. -S. American types as. -crossing and frequent absence of. -extinction of. -Falconer on existence of. -as fossils. -Asa Gray on. -Plagiaulax as evidence of. -Wollaston on rarity in insects. Introduced plants, Sonchus in New Zealand as example of. -in N. America and Australia. -variability of. -Darwin on. Introductory Essay to Tasmanian "Flora," Hooker's. Ipswich, British Association meeting (1851). Iquique, nitrate of soda beds at. Ireland, Spanish plants in. Iris, flowers of. -nectar secretion of. Islands, comparison between species of rising and sinking. -fauna of. -introduction of plants. -products of. -plants with irregular flowers on. -subsidence of coral. -survival of ancient forms in. -volcanic. -comparison of age of continents and. -former greater extension of. "Island Life," Darwin's criticism of Wallace's. Isle of Wight, occurrence of Bee-orchis in. Isnardia palustris, range of. Isolation, Bentham underestimates importance of. -Darwin's opinion of. -importance of. -Wagner exaggerates importance of. -Weismann on effects of. Itajahy, F. Muller's narrow escape from flood of. Italy, flora of. Ivy, difference in growth of flowering and creeping branches. Jaeger, G., letter to. -on pangenesis and inheritance. James', Sir H., discussion in "Athenaeum" on change of climate. -map of the world. James Island, Darwin's plants from. Jameson. Jamieson, W., on S. America. -Darwin converted to glacial theory of Glen Roy after publication of paper by. Janet, on Natural Selection. Japan, American types in. -flora of. -Gray's work on plants of. -progress of. Java, botanical relation to Africa. -Alpine plants of. -Wallace on. Jays, Crows and. -repeated pairing of. Jeffreys, Gwyn, shells sent by Darwin to. Jenkin, Fleeming, review by. Jenners, taste for natural history in the. Jenyns (Blomefield), Rev. Leonard: The following sketch of the life of Rev. Leonard Blomefield is taken from his "Chapters in my Life; Reprint with Additions" (privately printed), Bath, 1889. He was born, as he states with characteristic accuracy, at 10 p.m., May 25th, 1800; and died at Bath, September 1st, 1893. His father--a second cousin of Soame Jenyns, from whom he inherited Bottisham Hall, in Cambridgeshire--was a parson-squire of the old type, a keen sportsman, and a good man of business. Leonard Jenyns' mother was a daughter of the celebrated Dr. Heberden, in whose house in Pall Mall he was born. Leonard was educated at Eton and Cambridge, and became curate of Swaffham Bulbeck, a village close to his father's property; he was afterwards presented to the Vicarage of the parish, and held the living for nearly thirty years. The remainder of his life he spent at Bath. He was an excellent field-naturalist and a minute and careful observer. Among his writings may be mentioned the Fishes in "Zoology of the Voyage of the 'Beagle,'" 1842, a "Manual of British Vertebrate Animals," 1836, a "Memoir" of Professor Henslow,1862, to which Darwin contributed recollections of his old master, "Observations in Natural History," 1846 and "Observations in Meteorology," 1858, besides numerous papers in scientific journals. In his "Chapters" he describes himself as showing as a boy the silent and retiring nature, and also the love of "order, method, and precision," which characterised him through life; and he adds, "even to old age I have been often called a VERY PARTICULAR GENTLEMAN." In a hitherto unpublished passage in his autobiographical sketch, Darwin wrote, "At first I disliked him from his somewhat grim and sarcastic expression; and it is not often that a first impression is lost; but I was completely mistaken, and found him very kind- hearted, pleasant, and with a good stock of humour." Mr. Jenyns records that as a boy he was by a stranger taken for a son of his uncle, Dr. Heberden (the younger), whom he closely resembled. -letters to. -mentioned. Jodrell Laboratory, Darwin's interest in. -note on. Jordanhill, Smith of, on Gibraltar. "Journal of Researches," Darwin's. Judd, Prof. J.W., letter to. -recollections of Darwin. -on Darwin's "Volcanic Islands." -Darwin in praise of work of. Jukes, on imperfection of the Geological Record. -on changes of climate. -on formation of river-valleys. -over estimates sub-aerieal denudation. Jumps, variation by. Juncus, range of. -J. bufonius. -variation of. -germination of seed from mud carried by woodcock. Jura, Darwin on erratic blocks of. Jussieu, A. de. Kane's, E.K., "Arctic Explorations," use of foxtails by Esquimaux referred to in. Kelvin, Lord, Address at the British Association Meeting at Edinburgh (1871). -on geological time. -on age of the earth. -on origin of plant-life from meteorites. Kemp, W., sends seeds to Darwin. -on vitality of seeds. Kensington, proposed removal of British Museum (Bloomsbury) collections to. Kerguelen cabbage, Chambers versus Hooker on the. Kerguelen island, coal-beds of. -relation of flora to that of Fuegia. -similarity between plants of S. America and of. -importance of collecting fossil plants on. -moth from. -sea-shells of. -volcanic mountain on. Kerner, A. von Marilaun, on Tubocytisus. -"Pflanzenleben." -"Schutzmittel des Pollens." -on xenogamy and autogamy. -mentioned. Kerr, on frozen snow. Kerr, Prof. Graham. Kew, proposed consolidation of botanical collections at. -rarity of insects and shells in Royal Garden. -Darwin visits Garden. -Darwin obtains plants from. -Darwin sends seeds to. -Jodrell, Laboratory at. -struggle for existence at. -suggestion that J. Scott should work in Garden. Kilauea, lava in crater of. Kilfinnin, shelves in valley of. Kilima Njaro, plants of. King, Captain, collection of plants by. -"Voyages of the 'Adventure' and 'Beagle.'" King, Sir George, reminiscences of J. Scott. -Darwin receives seeds from. King, Dr. Richard (1811?-1876): He was surgeon and naturalist to Sir George Back's expedition (1833-5) to the mouth of the Great Fish River in search of Captain Ross, of which he published an account. In 1850 he accompanied Captain Horatio Austin's search expedition in the "Resolute." -Arctic expedition. Kingfisher, sexual difference in. Kingsley, C., quoted in the "Origin." -story of a heathen Khan. -reference to E. Forbes and P.H. Gosse. Kini Balu, vegetation of. Kirby and Spence. Klebs, on use of mucus in seeds. Knight, A., on crossing. -hybrid experiments. -on sports. Knight's Law. Knight-Darwin Law, F. Darwin on. Knuth, on morphology of cruciferous flower. Koch's "Flora Germanica." Kolliker, visits Down. Kollmann, Dr., on atavism. Kolreuter, on Aquilegia. -on hybrids. -observations on pollen. -on self-fertilisation. -on varieties of tobacco. "Kosmos," F. Muller's article on Crotolaria. -F. Muller's paper on Phyllanthus in. Krause, E., letter to. -memoir of Erasmus Darwin. -memoir of H. Muller. Kroyer. Kubanka, form of Russian wheat. Kurr, on flowers of Canna. La Plata, H.M.S. "Beagle's" visit to. -Cervus of. -Mylodon of. -plants of. -extinct animals from. -slates and schists of. Labellum, nature of. Labiatae, large genera of. Laboratory, Darwin on the instruments for botanical. -founding of Jodrell. Laburnum, peloric flowers of. -Darwin on hybrid (see also Cytisus). Ladizabala, crossing experiments on. Lagerstraemia (Lagerstroemia), F. Muller on. Lakes, Darwin on Ramsay's theory of. -as agents in forming Parallel Roads of Glen Roy. -of Friesland. -Geological action of. -Ramsay on. Lamarck, Darwin on views of. -difference between views of Darwin and. -"Hist. Zoolog." of. -Hopkins on Darwin and. -Packard's book on. -quotation from. Lamellicorns, F. Muller on sexes in. -stridulating organs of. Lamont, James, F.G.S., F.R.G.S.: author of "Seasons with the Sea-horses; etc.; Yachting in the Arctic Seas, or Notes of Five Voyages of Sport and Discovery in the Neighbourhood of Spitzbergen and Novaya Zemlya," London, 1876; and geological papers on Spitzbergen. -letters to. Lampyridae, luminous organs of. Land, fauna of sea compared with that of. -changes in level of sea the cause of those on. Land-birds, resting on the sea. Land-shells, dispersal of. -of glacial period. -modification of. Land-surfaces, preservation for long periods. Landois, reference to paper by. Language, observations bearing on origin of. -Sir J. Herschel on study of. Lankester, E. Ray, letter to. -drawing of earthworm used in Darwin's book. Lankester, E. (Senior), speech at Manchester British Association meeting (1861), on Darwin's theory. Lantana, in Ceylon. Lanugo, on human foetus. Lapland, richness of flora. Latania Lodigesii, peculiar to Round Island. Latent characters, tendency to appear temporarily in youth. Lathyrus aphaca. -L. grandiflorus, fertilisation of. -L. nissolia, evolution of. -explanation of grass-like leaves. -Darwin on. -L. maritimus, bloom on. -L. odoratus, fertilisation of. -intercrossing of varieties. Lauder-Dick, Sir Thomas, on Parallel Roads of Glen Roy. Laurel, extra-floral nectaries of. Lava, Darwin and Scrope on separation of constituent minerals of. -Elie de Beaumont's measurements of inclination of. -fluidity of. -junction between dykes and. -and metamorphic schists. -Scrope on basaltic and trachytic. -subsidence due to outpouring of. Law, of balancement. -of growth. -of higgledy-piggledy. -of perfectibility by Nageli. -of sterility. -of succession. -of variation. Lawes, Sir J.B., and Sir J.H. Gilbert, Rothamsted experiments. Laxton, T., close on the trail of Mendelian principle. "Lay Sermons," Huxley's. Leaves, movements of. -used by worms in plugging burrows. Lebanon, glacial action on. -plants of. -Hooker on Cedars of. Lecky, Rt. Hon. W.E.H., Darwin's interest in book by. -quoted in "Descent of Man." Lecoq, "Geographie Botanique." -on self-sterility. -mentioned. Lectures, Darwin on Edinburgh University, (see also Hooker and Huxley). -Max Muller's, on Science of Language. Ledebour, allusion to book by. Leeds, address by Owen at. Leersia oryzoides, cleistogamic flowers of. Leggett, W.H., on Rhexia virginica. Legitimate unions, heteromorphic or. Leguminosae, absence in Greenland. -absent in New Zealand. -anomalous genera in. -crossing in. -scarcity in humid temporate regions. -seeds of. -example of inherited pelorism in. -Lord Farrer's observations on fertilisation of. -nectar-holders in flowers. -reason for absence of. Leibnitz, rejection of theory of gravity by. Lemuria, continent of. Lepadidae, Darwin's work on, (see also Barnacles). -fossil. Lepas, nomenclature of. Lepidodendron. Lepidoptera, Sexual Selection in. -breeding in confinement. -F. Muller on mimicry in. -protection afforded by wings. -want of colour-perception. -Weir on apterous. Lepidosiren, reason for preservation of. Leptotes. Leschenaultia, fertilisation mechanism. -self-fertilisation of. -L. biloba, fertilisation mechanism of. -L. formosa, fertilisation mechanism of. Lesquereux, Leo (1806-89): was born in Switzerland, but his most important works were published after he settled in the United States in 1848. Beginning with researches on Mosses and Peat, he afterwards devoted himself to the study of fossil plants. His best known contributions to Palaeobotany are a series of monographs on Cretaceous and Tertiary Floras (1878-83), and on the Coal-Flora of Pennsylvania and the United States generally, published by the Second Geological Survey of Pennsylvania between 1880 and 1884 (see L.F. Ward, Sketch of Palaeobotany, "U.S. Geol. Surv., 5th Ann. Rep." 1883-4; also "Quart. Journ. Geol. Soc." Volume XLVI., "Proc." page 53, 1890. -convert to evolution. -on Coal floras. Leuckart, Rudolf (1822-98): Professor of Zoology at Leipzig. -convert to Darwin's views. Lewes, G.H., (1817-78): author of a "History of Philosophy," etc. -letter to. Lewy, Naphtali, letter to Darwin from. Lias, cephalopods from the. Life, Bastian's book on the beginnings of. -mystery of, -origin of. -principle of. -bearing of vitality of seeds on problem of. Light, action on plants of flashing. Lima, Darwin visits. Limulus. Linaria, peloria as reversions. Lindley, John (1799-1865): was born at Catton, near Norwich. His first appointment was that of Assistant Librarian to Sir Joseph Banks. He was afterwards Assistant Secretary to the Horticultural Society, and during his tenure of that office he organised the first fruit and flower shows held in this country. In 1829 he was chosen to be the first Professor of Botany at University College, London, and a few years later he became Lecturer to the Apothecaries' Company. He is the author of a large number of botanical books, of which the best known is the "Vegetable Kingdom," 1846. He was one of the founders of the "Gardeners' Chronicle," and was its principal editor up to the time of his death. He was endowed with great powers of work and remarkable energy. He is said as a young man to have translated Richard's "Analyse du Fruit" in a single sitting of three nights and two days. (From the article on Lindley in the "Dictionary of National Biography," which is founded on the "Gardeners' Chronicle," 1865, pages 1058, 1082.) -Hooker's eloge of. -and Royal Medal. -"Vegetable Kingdom" by. -on Acropera and Gongora. -Darwin on his classification of orchids. -letters to. -on Melastomaceae. -on orchids. -Hooker reviews Darwin's Orchid book in style of. -mentioned. Lingula, persistence of. -Silurian species. Link, on Alpine and Arctic plants. Linnaeus. Linnean Society, Bentham's address. -Collier's picture of Darwin in rooms of. -Darwin's paper on Linum. -Darwin advises Bates to give his views on species before. -Wallace's paper on the Malayan papilionidae. Linnet, a migratory bird. Linope, E. Hackel on. Linum, Darwin's work on. -dimorphism of. -interaction of pollen and stigma. -mucus in seeds of. Linum flavum. -L. grandiflorum, two forms of. -L. Lewisii, experiments on. -L. trigynum. -L. usitatissimum, circumnutation of. Lister, Lord, on spines of Hedgehog. Listera, fertilisation of. -L. cordata, fertilisation of. -L. ovata, fertilisation of. Litchfield, Mrs. (see Darwin, Henrietta). -criticism of Huxley. Littoral shells, glacial period and. Liverpool, British Association meeting at (1870). Livingstone, D., on the distribution of thorny plants. Lobelia, Darwin's experiments on. -fertilisation mechanism of. -fertility of. -L. fulgens, Scott's experiments on. Lochaber, Parallel Roads of (see also Glen Roy). -evidence of ice-action. Lochs, Laggan (Loggan), ice-action in. -Roy, Darwin disbelieves in existence of. -Spey, shelves of. -Treig, ice-action in. -Milne's account of. Locust grass, germination of. Locusts, blown out to sea. -plants from dung of. Logwood, leaf-movement of. -See Haematoxylon. Loiseleuria procumbens. London clay, supposed germination of seeds from. "London Review," Darwin's opinion of. -correspondence between Owen and editor in reference to "Origin." Longchamps, L. de, on crossing in Gramineae. Longevity, Darwin on animals' and man's. Lonsdale, William (1794-1871): obtained a commission in the 4th Regiment at the age of sixteen, and served at Salamanca and Waterloo. From 1829 to 1842 he held the office of Assistant-Secretary and Curator of the Geological Society. Mr. Lonsdale contributed important papers on the Devonian System, the Oolitic Rocks, and on palaeontological subjects. ("Quart. Journ. Geol. Soc." Volume XXVIII., page xxxv., 1872.) -mentioned. Lopezia, fertilisation of. Lophura viellottii, colour of. Loss, nature of. Love, evidence of existence low in scale. Loven, S.L.: published numerous papers on Cirripedes and other zoological subjects in the Stockholm "Ofversigt" and elsewhere between 1838 and 1882. -translation of paper on Cirripedes. -mentioned. Lowe, R.T., on Madeira. Lowell, Prof., on custom in Italy of shaking head in affirmation. Lowland plants, ascending mountains. Lowne, B.T., on anatomy of blowfly. Lowness and highness. Lubbock, Lady. Lubbock, Sir J., see Lord Avebury. Lucas, Dr. P., on tendency to vary independent of conditions. Ludwig, F., letter to. Lumbricus (see also Earthworms). Luminosity in animals. -result of external conditions. Lupinus, Darwin's experiments on. Luzula. Lychnis dioica, structure of flower. -sets seed without pollen. Lycopodium, variation in. Lyell, Sir Charles, Bart., F.R.S. (1797-1875): was born at Kinnordy, the family home in central Forfarshire. At the age of seventeen he entered at Exeter College, Oxford, and afterwards obtained a second class in the final Honours School in Classics. As an undergraduate Lyell attended Prof. Buckland's lectures on Geology. On leaving Oxford Lyell was entered at Lincoln's Inn; a weakness of the eyes soon compelled him to give up reading, and he travelled abroad, finding many opportunities for field work. He was called to the Bar in 1825, and in the same year published some papers on geological subjects. From 1823-26 Lyell filled the post of Secretary to the Geological Society, and in 1826 was elected into the Royal Society. In 1830 the first volume of the "Principles of Geology" was published; the second volume appeared two years later. Speaking of this greatest of Lyell's services to Geology, Huxley writes: "I have recently read afresh the first edition of the "Principles of Geology," and when I consider that this remarkable book had been nearly thirty years in everybody's hands [in 1859], and that it brings home to any reader of ordinary intelligence a great principle and a great fact-- the principle that the past must be explained by the present, unless good cause be shown to the contrary; and the fact that, so far as our knowledge of the past history of life on our globe goes, no such cause can be shown--I cannot but believe that Lyell, for others, as for myself, was the chief agent in smoothing the road for Darwin" (Huxley's "Life and Letters," Volume II., page 190). As Professor of Geology in King's College, London, Lyell delivered two courses of lectures in 1832- 33; in the latter year he received a Royal medal, and in 1858 he was the recipient of the Copley medal of the Royal Society. The "Elements of Geology" was published in 1833; this work is still used as a text-book, a new edition having been lately (1896) brought out by Prof. Judd; in 1845 and in 1849 appeared the "Travels in North America" and "A Second Visit to the United States of North America." The "Antiquity of Man" was published in 1863. Lyell was knighted in 1848, and in 1864 was raised to the rank of a Baronet. He was buried in Westminster Abbey. Darwin wrote in his Autobiography: "The Science of Geology is enormously indebted to Lyell, more so, as I believe, than to any other man who ever lived" ("Life and Letters," Volume I., page 72). In a letter to Lyell-- November 23rd, 1859--Darwin wrote: "I rejoice profoundly that you intend admitting the doctrine of modification in your new edition [a new edition of the "Manual" published in 1865]; nothing, I am convinced, could be more important for its success. I honour you most sincerely. To have maintained, in the position of a master, one side of a question for thirty years, and then deliberately give it up, is a fact to which I much doubt whether the records of science offer a parallel" ("Life and Letters," Volume II., pages 229-30). See "Life, Letters, and Journals of Sir Charles Lyell, Bart." edited by his sister-in-law, Mrs. Lyell, 2 Volumes, London, 1881. "Charles Lyell and Modern Geology," Prof. T.G. Bonney, London, 1895.) -"Antiquity of Man." -on Barrande. -cautious attitude towards "Origin of Species." -cautious judgment of. -on Cetacea. -Copley medal awarded to. -on continental extension. -controversy with Owen. -Darwin's pleasure in reading his "Geology." -on distribution. -Falconer and. -German opinion of. -on immutability. -interest in celts. -letters to. -letters to Darwin from. -map of Tertiary geography by. -on mutability. -on pangenesis. -"Principles of Geology." -on Ramsay's theory of lakes. -urges Darwin to publish his views with those of Wallace. -visits Down. -work in France. -address to Geological Society. -attacked by Owen in his "Anatomy of Vertebrata." -criticism of Murchison. -on craters of denudation. -Darwin's indebtedness to. -death of. -death of his father. -gives up opposition to Evolution. -on glaciers of Forfarshire. -on glacial period in S. hemisphere. -versus Herschel on volcanic islands. -on iceberg action. -memorial in Westminster Abbey. -on Parallel Roads of Glen Roy. -as founder of school of Geology. -second visit to the United States. -trip to Wales. -mentioned. Lyell, Lady, letter to. -translation of paper for Darwin. -visits Down. -mentioned. Lynch, R.I. Lythraceae, dimorphism in. Lythrum, cross-fertilisation of. -Darwin's work on. -trimorphism of. -L. hyssopifolium, range of. -L. salicaria, dimorphism of. -Darwin's work on. Macacas, Owen on. -M. Silenus, mane as a protection. Macalister, Prof. A. Macarthur, Sir W., on Erythrina. Macaw, beauty of plumage. McClennan, on primitive man. MacCulloch, on Glen Turret. -on metamorphic rocks. -on Parallel Roads of Glen Roy. M'Donnell, Darwin on work of. Macgillivray, reference to his "History of British Birds." Machetes pugnax, polygamy of. Mackintosh, Daniel (1815-91): was well-known in the South of England as a lecturer on scientific subjects. He contributed several papers to the Geological Society on Surface Sculpture, Denudation, Drift Deposits, etc. In 1869 he published a work "On the Scenery of England and Wales" (see "Geol. Mag." 1891, page 432. -on boulders of Ashley Heath. -letters to. -on Moel Tryfan. -on sources of erratic blocks in England. McNab, Prof., J. Scott and. -mentioned. Macrauchenia, skull of. Madagascar, existence of insects capable of fertilising Angraecum in. -fossil Hippopotamus of. -Owen on fauna of. -plants of. -former extension of. -as a geographical region. -Viola of. Madeira, birds of. -British plants compared with those of. -Canary Islands formerly connected with. -flora of. -insects of. -land-extension, of. -land-shells of. -Lowe on. -Tertiary plants of. -elevation of. Maer, the home of the Wedgwoods. Magellan Straits, H.M.S. "Beagle" in. Magnus, review by Krause of his work on colour. Magpies, pairing of. Mahon, Lord, compliment to Darwin. Mahonia, natural crossing of. Maillet, evolutionary views of. Maize, hybrids of, see also Zea. Malaxeae, and Epidendreae. Malaxis, course of vessels in flower. -fertilisation of. Malaxis paludosa, epiphytic on Sphagnum. Malay archipelago, Darwin on Wallace's book on. -translation by Meyer of Wallace's book. Malay region, glacial epoch and the. -Wallace on butterflies and pigeons of. Malpighiaceae, degraded flowers of. -Erythroxylon included in. Malta, Forbes on geology of. Malthus, Darwin derives help from reading. -Haughton sneers at. -misunderstood. Malva. Mammae, as rudimentary organs in man. Mammals, alteration in skulls of. -Australian cave-. -birds compared with. -Dana's classification. -distribution. -as indices of climatic changes. -as proof of union between England and Continent since Glacial period. -Waterhouse's "Natural History" of. -Glacial period and extinction of. -Origin and migration. Mammoth (Bog). Mammoth, Darwin's eagerness to collect bones of. -Falconer on the. Man, antiquity of (see "Antiquity of Man," and Lyell, Sir C.). -and apes. -brain of. -criticism of Lyell's chapter on. -Huxley's book on. -McClennan on primitive. -and Natural Selection. -origin of. -races of. -selection by Nature contrasted with selection by. -slow progress of. -Darwin on Wallace's paper on. -descent of. -ears of. -geological age of. -and geological classification. -hairyness of. -introduction of. -rank in classification. -Turner on evolution of. -Wallace on evolution of. Mankind, descent from single pair. -early history of. -progress of. Mantell, Owen's attack on. "Manual of Scientific Inquiry," Darwin's. Manx cats. Maranta, sleep-movements of. Marble, MacCulloch on metamorphism of. Marianne Islands, subsidence of. -want of knowledge of flora. Marion, "L'evolution du Regne vegetal," by Saporta and. Marlatt, C.L., on Cicada. Marquesas Islands, subsidence of. Marr, J.E., on the rocks of Bohemia. -mentioned. Marriage, Darwin on. -Galton's proposal to issue health-certificates for. Marshall, W., on Elodea. Marsupialia, compared with placentata. -Darwin on nature of. -evidence of antiquity. -abundance in Secondary period. Martens, see Martins. Martha (=Posoqueria), F. Muller's paper on. Martin, H.N., Darwin's opinion of "Elementary Biology" by Huxley and. Martins, experiments on immersion of seeds in sea by. Maruta cotula of N. America. Masdevallia, Darwin's work on. Massart, on regeneration after injury. Masters, M., letters to. -lecture at Royal Institution. -"Vegetable Teratology." Mastodon, Australian. -extinction of. -Falconer on. -in Timor. -migration into S. America. -skeleton found by Darwin. -M. andium, Falconer on intermediate character of. "Materialism of the Present day," Janet's. Matteucci on electric fishes. Matthew, P., on forest trees in Scotland. -quoted by Darwin as having enunciated principle of Natural Selection before "Origin." Maurienne, note on earthquake in province of. Mauritius, craters of. -elevation of. -extinction of snakes of. -oceanic character of. Maury's map, as illustrating continental extension. Maxillaria. Maypu River, Darwin visits. Mays, J.A., publishes lectures by Huxley. Medals: -(Copley), Darwin, Lyell. -(Royal). -(Wollaston), Darwin. Medical Department of Army, statistics from Director-General of. Meditation, expression of eyes in. Mediterranean Islands, flora of. Medusae, Romanes' work on. Meehan, T., letter to. Megalonyx. Megatherium, Darwin collects bones of. -Sir A. Carlisle on. Melastoma, Darwin on. Melastomaceae, Darwin on. -crossing in. -two kinds of stamens in. Meldola, Prof. Raphael F.R.S.: Professor of Chemistry in Finsbury Technical College (City and Guilds of London Institute), and a well- known entomologist; translated and edited Weismann's "Studies in the Theory of Descent," 1882-83. -address to Entomological Society. -letters to. -translation of Weismann's "Studies in Descent" by. -on Weismann and Darwin. -mentioned. Melipona. Meloe, Lord Avebury on. Melrose, seeds from sandpit near. Memorial to the Chancellor of the Exchequer. Mendel, G., W. Bateson on his "Principles of Heredity." -Darwin ignorant of work of. -Laxton and. Mendoza, Darwin visits. "Mental Evolution in Animals," Romanes'. Mentha, of N. America. -M. borealis, variety in N. America. Menura superba, colour and nests of. Menzies and Cumming, visit Galapagos Islands. Mercurialis. Mertensia, Darwin's experiments on. Mesembryanthemum. Mesotherium, Falconer on. Metamorphic schists. Metamorphism, Darwin on. -heat and. -Sorby on. Metamorphosis, Lord Avebury on insects and. -F. Muller on. -Quatrefages on. Meteorites, Lord Kelvin suggests their agency in introduction of plants. "Methods of Study," Agassiz' book on. Mexicans, explanation of natural affinities of Chinese and. Meyen, on insectivorous plants. Meyer, Dr., translator of Wallace's "Malay Archipelago." Meyer and Doege, on plants of Cape of Good Hope. Mica, in foliated rocks. Mica-slate, clay-slate and. Mice, ears of. -experiments by Tait on. Microscope, Darwin on convenient form of. -indispensable in work on flowers. -use of compound without simple, injurious to progress of Natural History. Migration of animals and plants. -Darwin on plant-. -of elephants. -Glacial period and. -of plants. -in tropics. -of birds. Mikania, a leaf-climber. -M. scandens, gradation between Mutisia and. Mill, J.S., on Darwin's reasoning. -on greatest happiness principle. Miller, Hugh, "First Impressions of England and its People." Miller, S.H., "Fenland Past and Present" by Skertchley and. Miller, Prof. William Hallowes, F.R.S. (1801-80), held the Chair of Mineralogy at Cambridge from 1832 to 1880 (see "Obituary Notices of Fellows," "Proc. R. Soc." Volume XXXI., 1881). He is referred to in the "Origin of Species" (Edition VI., page 221) as having verified Darwin's statement as to the structure of the comb made by Melipona domestica, a Mexican species of bee. The cells of Melipona occupy an intermediate position between the perfect cells of the hive-bee and the much simpler ones of the humble-bee; the comb consists "of cylindrical cells in which the young are hatched, and, in addition, some large cells of wax for holding honey. These latter cells are nearly spherical and of nearly equal sizes, and are aggregated into an irregular mass. But the important point to notice is that these cells are always made at that degree of nearness to each other that they would have intersected or broken into each other if the spheres had been completed; but this is never permitted, the bees building perfectly flat walls of wax between the spheres which thus tend to intersect." It occurred to Darwin that certain changes in the architecture of the Melipona comb would produce a structure "as perfect as the comb of the hive-bee." He made a calculation, therefore, to show how this structural improvement might be effected, and submitted the statement to Professor Miller. By a slight modification of the instincts possessed by Melipona domestica, this bee would be able to build with as much mathematical accuracy as the hive-bee; and by such modifications of instincts Darwin believed that "the hive-bee has acquired, through natural selection, her inimitable architectural powers" (loc. cit., page 222). -letters to. Million years, Darwin on meaning of a. Milne-Edwards, Darwin's cirripede work and. -Darwin's opinion of. -on retrograde development. Milne-Home, David (1805-90): was a country gentleman in Berwickshire who became interested in geology at an early age. He wrote on the Midlothian Coal-field, the Geology of Roxburghshire, the Parallel Roads of Glen Roy, and compiled the Reports presented by a Committee appointed by the Royal Society of Edinburgh to investigate the observation and registration of boulders in Scotland ("Quart. Journ. Geol. Soc." Volume XLVII., 1891; "Proc." page 59). -believes in connection between state of weather and earthquakes. -on Glen Roy. -letters to. -letter from R. Chambers to. -on oscillation of sea. Milton, quotation from. Mimicry, Bates on. -and dimorphism. -Volucella as an example of. -Wallace on. -and colour. -F. Muller on Lepidoptera and. Mimosa, Darwin's experiments on. -M. albida, Darwin on. -M. sensitiva. Mimoseae, F. Muller's account of seeds of. Mimulus, Pfeffer on movement of stigma. Mind, development of. -evolution of. -influence on nutrition. Miocene land. Miquel, F.A.W., on Flora of Holland. -on distribution of the beech. -on flora of Japan. -mentioned. Mirabilis. Mirbel, G.F.B. de. Miscellaneous letters, botanical. -geological. Miscellaneous subjects, letters on. Mississippi, Lyell on pampas and deposits of the. Mitchella. Mivart, St. George F.R.S. (1827-1900): was educated at Harrow, King's College, London, and St. Mary's College, Oscott. He was called to the Bar in 1851; in 1862 he was appointed Lecturer in the Medical School of St. Mary's Hospital. In the "Genesis of Species," published in 1871, Mivart expressed his belief in the guiding action of Divine power as a factor in Evolution. -false reasoning of. -"Genesis of Species." Modification, Darwin's disbelief in sudden. -explanation of. -of insects. -of jays and crows. -of land and freshwater faunas. -selection and. -of species. -Walsh on specific. Moel Tryfan, Darwin on shells on. -Mackintosh on shells on. Moggridge, J. Traherne (1842-74): is described by a writer in "Nature" Volume XI., 1874, page 114, as "one of our most promising young naturalists." He published a work on "Harvesting Ants and Trap-door Spiders," London, 1873, and wrote on the Flora of Mentone and on other subjects. (See "The Descent of Man" Volume I., Edition II., page 104, 1888.) -letters to. -note on. -experiments on ants and seeds. Mohl, von, on climbing plants. Mojsisovics, E. von: Vice-Director of the Imperial Geological Institute, Vienna. -letters to. -work on Palaeontology and Evolution. Molecular movement in foliated rocks. Moller, "Brasilische Pilzblumen." Molliard, on Les Cecidies florales. Mollusca, distribution by birds. -Huxley on. -means of dispersal of. -Morse on protective colours of. -Wallace on distribution of. Molothrus, occurrence in Brazil. Monacanthus viridis, female form of Catasetum tridentatum. Monkeys, distribution of birds affected by. -range of. -ears of. -mane as protection. -wrinkling of eyes during screaming. Monochaetum (Monochoetum), absence of nectar in. -experiments on. -flowers of. -neglected by bees. -seeds of. -M. ensiferum, two kinds of stamens. Monocotyledons, range of. -heterostylism in. Monotremes, birds compared with. -as remnant of ancient fauna. Monotropa uniflora, in New Granada. -in Himalayas. -in separate areas in U.S.A. Monotypic genera, variation of. Monstrosities, Harvey on. -Masters' work on. -no sharp distinction between slight variations and. -origin of species from. -variations and. Monte Video, Darwin visits. -Darwin on cleavage at. Moon, effect on earthquakes. Moraines, glacial. Moral sense, J. Morley on Darwin's treatment of. Morality, foundation of. More, Alexander Goodman (1830-95): botanist and zoologist, distinguished chiefly by his researches on the distribution of Irish plants and animals. He was born in London, and was educated at Rugby and Trinity College, Cambridge. He became Assistant in the Natural History Museum at Dublin in 1867, and Curator in 1881. He was forced by ill-health to resign his post in 1887, and died in 1895. He is best known for the Cybele Hibernica and for various papers published in the "Ibis." He was also the author of "Outlines of the Natural History of the Isle of Wight," of a "Supplement to the Flora Vectensis," and innumerable shorter papers. His "Life and Letters" has been edited by Mr. C.B. Moffat, with a preface by Miss Frances More (1898). There is a good obituary notice by Mr. R. Barrington in the "Irish Naturalist," May, 1895. -letters to. Morgan. Morley, J., letters to. Mormodes, labellum of. -M. ignea, flower of. Morphological, Hooker's criticism of term. -sense in which used by Nageli. Morphology, Darwin's explanation of. -Kollmann on batrachian. -of plants. Morse, Prof. E.S.: of Salem, Mass. -letters to. -on shell-mounds of Omori. Morton, Lord, his mare. Moscow, opinion on Darwin's work from. Moseley, Canon H., on glacier-motion. Moseley, Prof. Henry Nottidge F.R.S. (1844-91): was an undergraduate of Exeter College, Oxford, and afterwards studied medicine at University College, London. In 1872 he was appointed one of the naturalists on the scientific staff of the "Challenger," and in 1881 succeeded his friend and teacher, Professor Rolleston, as Linacre Professor of Human and Comparative Anatomy at Oxford. Moseley's "Notes by a Naturalist on the Challenger," London, 1879, was held in high estimation by Darwin, to whom it was dedicated. (See "Life and Letters," III., pages 237-38.) -letter to. -proposal to examine Kerguelen Coal beds. Moss-rose, sudden variation in. Mostyn, Lord, horse and quagga belonging to. Moths, hermaphroditism in hybrid. -survival of distinct races. -colours of. -and Sexual Selection. Mould, Darwin's opinion of his paper on. Mountain-building, Rogers on. Mountain-chains, Darwin on. -and earthquakes. -and elevation. -false views of geologists on. -Hopkins on. -volcanic rocks in. Movement, of land-areas. -of plants, Darwin on. -F. Muller on. -Wiesner on Darwin's book on. Mucus of seeds, significance of. Mukkul, Pass of. Mules, meaning of stripes of. -J.J. Weir's observations on. Muller, Ferd., on advance of European plants in Australia. Muller, (Fritz) Dr. Johann Friedrich Theodor (1822-97): was born in Thuringia, and left his native country at the age of thirty to take up his residence at Blumenau, Sta Catharina, South Brazil, where he was appointed teacher of mathematics at the Gymnasium of Desterro. He afterwards held a natural history post, from which he was dismissed by the Brazilian Government in 1891 on the ground of his refusal to take up his residence at Rio de Janeiro ("Nature," December 17th, 1891, page 156). Muller published a large number of papers on zoological and botanical subjects, and rendered admirable service to the cause of evolution by his unrivalled powers of observation and by the publication of a work entitled "Fur Darwin" (1865), which was translated by Dallas under the title "Facts and Arguments for Darwin" (London, 1869). The long series of letters between Darwin and Muller bear testimony to the friendship and esteem which Darwin felt for his co-worker in Brazil. In a letter to Dr. Hermann Muller (March 29th, 1867), Mr. Darwin wrote: "I sent you a few days ago a paper on climbing plants by your brother, and I then knew for the first time that Fritz Muller was your brother. I feel the greatest respect for him as one of the most able naturalists living, and he has aided me in many ways with extraordinary kindness." See "Life and Letters," III., page 37; "Nature," October 7th, 1897, Volume LVI., page 546. -book by. -convert to Darwin's views. -Darwin's opinion of his book. -friendship with Darwin. -Hooker on. -letters to. -on Lord Morton's mare. -on mutual specialisation of insects and plants. -on prawns. -reference to letter from. -on sponges. -on Cassia and caterpillars in S. Brazil. -on climbing plants. -on crossing plants. -Darwin offers to make good loss by flood. -Darwin's admiration of. -on Darwin's work on lepidoptera. -Darwin urges him to write Natural History book. -explanation of two kinds of stamens in flowers. -on fertilisation mechanisms. -letter to Darwin from. -narrow escape from flood. -article in "Kosmos" on Phyllanthus. -on Melastomaceae. -on orchids. -on stripes and spots in animals. -on Termites. -disinclined to publish. -mentioned. Muller, Hermann (1829-83): began his education in the village school of Muhlberg, and afterwards studied in Halle and Berlin. From an early age he was a keen naturalist, and began his scientific work as a collector in the field. In 1855 he became Science teacher at Lippstadt, where he continued to work during the last twenty-eight years of his life. Muller's greatest contribution to Botany "Die Befruchtung der Blumen durch Insekten," was the outcome to Charles Darwin's book on the "Fertilisation of Orchids." He was a frequent contributor to "Kosmos" on subjects bearing on the origin of species, the laws of variation, and kindred problems; like his brother, Fritz, Hermann Muller was a zealous supporter of evolutionary views, and contributed in no small degree to the spread of the new teaching. ("Prof. Dr. Hermann Muller von Lippstadt: Ein Gedenkblatt," by Ernst Krause, "Kosmos," Volume VII., page 393, 1883.) -extract from letter to. -Darwin's admiration for his book. -on fertilisation of flowers. -on clover and bees. -on Epipactis and Platanthera. -extract from Darwin's preface to his "Befruchtung der Blumen." -letters to. -on Melastoma. -persecuted by Ultramontane party. -review in "Kosmos" of "Forms of Flowers." -mentioned. Muller, Prof. Max, "Lectures on the Science of Language." -letter to. Muller, Rosa, observations on circumnutation. Mummy wheat. Mundane cold period, Darwin on supposed. Mundane genera, distribution of. Munro, Col., on Bermuda. Munro, on eyes of parrots. Murchison, Sir R.I., apotheosis of. -Darwin's conversations with. -letter to. -address to Geological Society. -on structure of Alps. -Lyell's criticism of. Murder, expression of man arrested for. Murdoch, G.B., letter to. Murray, A., address to Botanical Society of Edinburgh. -criticism of Wallace's theory of nests. -Darwin criticised by. -Darwin's criticism of work of. -on geological distribution of mammals. -on leaves and CO2. -review of "Origin" by. -mentioned. Murray, Sir J., Darwin on his theory of coral reefs. Murray, J., Darwin's agreement with. -"Journal of Researches" published by. -MS. of "Origin" sent to. -sale of "Origin." -publication of "Fur Darwin." Mus, range of. Musca vomitoria, Lowne on. Muscles, contraction in evacuation and in labour pains. -in man and apes. Museum (British), enquiry as to disposal of Natural History Collections by Trustees of. Music, birds and production of. -insects, and. -origin of taste for. Musk-duck, hatching of eggs. Musk-orchids, pollinia of. Musk ox, as index of climate. -found in gravel at Down. Mussels, seize hold of fishing hooks. Mutability of species, Lyell on. Mutation, use of term. Mutisia, a tendril-climber, compared with Mikania. Myanthus barbatus, hermaphrodite form of Catasetum tridentatum. Mylodon. Myosotis, in N. America. Myosurus, range of. Mytilus, as fossil in the Andes. Nageli, Carl Wilhelm von (1817-91): was born at Kilchberg, near Zurich. He graduated at Zurich with a dissertation on the Swiss species of Cirsium. At Jena he came under the influence of Schleiden, who taught him microscopic work. He married in 1845, and on his wedding journey in England, collected seaweeds for "Die neueren Algen-systeme." He was called as Professor to Freiburg im Breisgau in 1852; and to Munich in 1857, where he remained until his death on May 10th, 1891. In the "Zeitschrift fur wiss. Botanik," 1844-46, edited by Nageli and Schleiden, and of which only a single volume appeared, Nageli insists on the only sound basis for classification being "development as a whole." The "Entstehung und Begriff" (1865) was his first real evolutionary paper. He believed in a tendency of organisms to vary towards perfection. His idea was that the causes of variability are internal to the organism: see his work, "Ueber den Einfluss ausserer Verhaltnisse auf die Varietatenbildung. Among his other writings are the "Theorie der Bastardbildung," 1866, and "Die Mechanisch-physiologische Theorie der Abstammungslehre," 1884. The chief idea of the latter book is the existence of Idioplasm, a part of protoplasm serving for hereditary transmission. (From Dr. D.H. Scott's article in "Nature," October 15th, 1891, page 580.) -Darwin on his work. -Essay on Natural Selection. -on Hieracium. -"Ueber Entstehung und Begriff der naturhistoriscehn Art." -Weismann on work of. -on arrangement of leaves. -criticism of Darwin. -on innate principle of development. -on physiological nature of useful adaptations in plants. Napier, Rt. Hon. J.R., speech at British Association (1861) on Darwin's work. Naravelia. Narborough, Sir J., description of W. coast of S. America by. Nascent organs, rudimentary and. -wing of Apteryx as. Natural classification. "Natural Conditions of Existence," Semper's. Natural History, Darwin's taste for. -Darwin's contributions to. -accuracy the soul of. -Darwin urges F. Muller to write book on. Natural History Collections, enquiry as to disposal by British Museum Trustees of. "Natural History Review," Lord Avebury on Walsh's paper on dimorphism. -Bentham in the. -Darwin's opinion of. -Darwin reviews Bates in. -Falconer in the. -founding of. -Huxley and. "Natural Inheritance," Galton's. Natural preservation, as substitute for Natural Selection. "Natural Science," A.S. Woodward on Neomylodon in. Natural Selection, accumulation of varieties by. -and adaptation in orchids. -Allen on slowness of action. -Angraecum in relation to. -Ansted on. -applied to politics. -and artificial. -Bates' belief in. -Bronn on. -comparison with architecture. -with force and matter. -with laws of gravity. -conservative influence of. -Cope's and Hyatt's views on. -Darwin accused of making too much of a Deus of. -Darwin's anxiety not to overestimate effect of. -Darwin lays stress on importance of. -Darwin on use of term. -deification of. -and direct action. -Eocene or Secondary organisms would be beaten in competition with recent on theory of. -and external conditions. -Falconer on. -and fertility. -Asa Gray on. -Harvey misunderstands Darwin's meaning. -Haughton partially admits. -Hooker thinks Darwin probably rides too hard his hobby of. -Hooker on supposed falling off in belief in. -Hooker and Bates believe in. -Huxley's belief in. -Huxley gives in a lecture inadequate idea of. -Hyatt and Cope on. -importance of. -Lamont on. -Lyell on. -and monstrosities. -Nageli's Essay on. -no limit to perfection of co-adaptations produced by. -non-acceptance of. -objections to. -"plants are splendid for making one believe in." -possibility of race of bears being rendered aquatic through. -with the principle of divergence the keystone of "Origin." -production of thorns through. -tends to progression of organisation. -providential arrangement and superfluity of. -struggle between reversion, variability and. -Scott on. -slowness of action. -and sterility. -success of. -tails of mice a difficulty as regards. -Sir W. Thomson's misconception of. -uses of. -value of. -and variation. -variation of species sufficient for selection and accumulation of new specific characters by. -and useful characters. -Wallace on. -Watson on. -applied to man and brutes. -Australian savages and. -beauty and. -Darwin on action of. -Darwin's historical sketch in "Origin" of. -difficulties of. -Donders nearly preceded Darwin in views on. -evolution of man from point of view of. -Owen's attitude towards. -primogeniture destructive of. -Sexual Selection less powerful than. -Wallace attributes theory entirely to Darwin. -Wallace on brain and. Naturalisation, of European plants. -of plants in India. -of plants in islands. Naturalised plants, Bentham on. -comparison of variability of indigenous and. -De Candolle on. -variability of. -fewness of American species of, in Britain. "Naturalist in Nicaragua," Belt's. -Belt's account of honey-glands of plants in. "Naturalist on the Amazons," Bates'. -Darwin's opinion of. Naturalists, views on species held by. -few care for philosophical experiments Nature, Wallace on personification of. -use of term. "Nature not lying," principle of. "Nature," Darwin's opinion of. -letters or notes from Darwin in. -Galton in. -F. Muller in. -Thiselton-Dyer in. Naudin, C., on hybridism. -on Melastomaceae. Nauplius stages. Nautilus, of Silurian age. Necrophorus, Darwin's observations on. Nectar, in leguminous flowers. -Lord Farrer on secretion of, in Coronilla. Nectaries, Belt on extra-floral. Nectarines and peaches. -Rivers on production from seed. -variation in. Negative geological evidence, Darwin and Lyell on. Negro, resemblance between expression of Cebus and. Nelumbium, as example of transport. Neottia nidus-avis, fertilisation mechanism. -pollen-tubes of. Nepenthes, Hooker's work on. -Thiselton-Dyer on. Neptunia. Nervous system, genesis of. -influence on nutrition. Nests, Wallace's theory, of. -colour in relation to. -instinct in making. Neumann, on Catasetum. Neumayr, Melchior (1845-90): passed his early life at Stuttgart, and entered the University of Munich in 1863 with the object of studying law, but he soon gave up legal studies for Geology and Palaeontology. In 1873 he was recalled from Heidelberg, where he held a post as Privatdocent, to occupy the newly created Chair of Palaeontology in Vienna. Dr. Neumayr was a successful and popular writer, as well as "one of the best and most scientific palaeontologists"; he was an enthusiastic supporter of Darwin's views, and he devoted himself "to tracing through the life of former times the same law of evolution as Darwin inferred from that of the existing world." (See Obit. Notice, by Dr. W.T. Blanford, "Quart. Journ. Geol. Soc." Volume XLVI., page 54, 1890.) -essay on descent theory. -services to geology. -"Die Stamme des Thierreichs." Nevill, Lady Dorothy. New Zealand, absence of leguminosae opposed to continental extension of. -British plants in. -clover never seeded before introduction of bees. -comparison between flora of Tasmania and. -elevation of mountains in. -flora of. -flora of Australia and. -Flora of Raoul Island and. -Hooker on flora of. -Darwin's opinion of Hooker's "Flora." -former connection of islands. -former extension of. -naturalised plants. -peopling of mountains by plants. -proportion of annuals. -species of plants common to America, Chili and. -stocked from Antarctic land. -colonising of. -glacial action in. -mountain-rat of. -trees of. Newton, Prof. A., note on Strickland by. -description of partridge as agent in dispersal of seeds. Newton's law of gravity. Niagara, Darwin on Lyell's work on. Nightingale, Gould on the. Noises, observations on children's. Nolana prostrata, Darwin's experiments on. Nomenclature, discussion on. "North British Review," Fleeming Jenkin's review in. -Tait in. Norton, Professor Charles Elliot: of Harvard, the son of the late Dr. Andrews Norton, Professor of Theology in the Harvard Divinity School. -visits Down. Norway, Von Buch's travels in. -Blytt on flora of. Norwich, Berkeley's address at British Association (1868) meeting at. -Hooker's address. Nottingham, British Association meeting (1866) at. -Hooker's lecture on insular floras at. Notylia, F. Muller on. Nucula, a persistent type. Nuneham, Darwin's recollection of trip to. Nutrition, influence of mind on. Nyctitropic movements, see Sleep-movements. Observation, spirit of astronomers in. -harder work than generalisation. -pleasure of. Observations, not to be trusted without repetition. Observer, a good theoriser makes a good. Oceanic islands, difference in floras and means of stocking. -connection between continents and. -former extension of. -Reade on. -volcanic nature of. Oceans, age and depth of. -permanence of. -as sinking areas. Ogle, W., on the sense of smell. -letter to. -translation of book by Kerner. Ogleby, reference to his nomenclature scheme. Oken, on Lepas. -Owen on. Old characters, reappearance of. Oldenburgia. Oldenlandia. Olfers. Oliver, D., Darwin indebted to for information. -letters to. -mentioned. Olyra, sleep-movements of. Omori, Morse on shell-mounds of. Oncidium, J. Scott's work on. -structure of labellum. -O. flexuosum, observations by Muller and Scott on. -self-sterility of. -O. sphacelatum, Scott on fertilisation of. Ophrys. -O. apifera, fertilisation-mechanism. -self-fertilisation of. -O. arachnites, fertilisation of. -habitat. -O. aranifera. -O. morio, fertilisation of. -O. muscifera, Lord Farrer's observations on. -O. scolopax. Opossums. Oppel, service to geology. -mentioned. Opuntia, Henslow describes new species from Galapagos. Orang-utang, Rolleston on brain of. -Wallace on. Orange trees, grafting of. d'Orbigny, on geology of S. America. -theory of formation of Pampas mud. -"Voyage dans l'Amerique meridionale. -mentioned. Orchids, adaptation in. -Darwin's work on. -Darwin's view that seedlings are parasitic on Cryptogams. -Falconer's estimate of Darwin's work on. -few species in humid temperate regions. -flourish in cool temperate regions. -illustrate diversity of means to same end. -monstrous. -quoted as argument against species arising from monstrosities. -utility and. -fertilisation mechanisms of. -Brazilian. -Darwin decides to publish his work in book-form. -Darwin sends copy of his book to F. Muller. -Darwin underrates power of producing seeds without insects. -French translation of Darwin's book. -germinative power of pollen. -Hildebrand's paper on. -Nectar not excreted in some English. -and nectar secretion. -formation of ovule after pollination. -Scott points out error in Darwin's work. -Scott on pollen-tubes of. -Scott on self-sterility. -self-fertilisation in. -setting of seed in unopened flower. -sterility of. -course of vessels in flowers. -wonderful contrivances intelligible. Orchis, flowers of. -nectaries of. -pollinia of. Orchis (Bee) (see also Ophrys apifera), Darwin's experiments on. -O. pyramidalis, fertilisation mechanism. -O. ustulata. Order of Nature. Ordination. Organ mountains, Darwin on plants of. -glacial action on. Organisms, simultaneous change in. -amount of change in fresh water and marine. Organs, transition of -use of. "Origin of the Fittest," Cope's. "Origin of Genera," Cope's work on. Origin of life. "Origin of Species," acceptance of doctrine of Evolution due to the. -Darwin's belief in the permanence of the framework of the. -Darwin's opinion of his book. -Dawson's review of. -direct action underestimated in the. -editions of the. -errors in. -Falconer's estimate of. -Huxley's Cambridge speech, and reference to the. -Huxley's lecture on coming of age of. -Huxley's review of. -Lesquereux's articles in "Silliman" against the. -publication of the Abstract of. -publication by Murray of. -sale of the. -Seemann on the. -translation of. -Wallace's criticism of. -Walsh on the. -Darwin on necessity for modifications in the. -review by Fleeming Jenkin. -review by A. Murray. -Owen's criticism of Darwin's Historical Sketch in 4th edition of. -Owen's review of. -study of natural history revolutionised by the. -valueless criticism on. Origin of species, Darwin's early views on. -Darwin's views on. -Falconer antagonistic to Darwin's views on. -Oxford discussion (British Association, 1860) on the. -spread of Darwin's views in America. Origin of species and genera, Wallace in the "Nineteenth Century" on. Original work, time taken up by, at expense of reading. Ormerod's Index to the Geological Society's Journal. Ornithorhynchus, aberrant nature of. -preservation of. Orthoptera, auditory organs of. Oscillariae, abundance in the ocean. Oscillataria. Oscillation of land, Darwin's views on. Os coccyx, as rudimentary organ. Ostrea. Ostrich, modification of wings. Outliers, plants as. "Outlines of Cosmic Philosophy," Fiske's. Ovary, abnormal structure in orchid. Owen, Sir Richard (1804-92): was born at Lancaster, and educated at the local Grammar School, where one of his schoolfellows was William Whewell, afterwards Master of Trinity. He was subsequently apprenticed to a surgeon and apothecary, and became deeply interested in the study of anatomy. He continued his medical training in Edinburgh and at St. Bartholomew's Hospital in London. In 1827 Owen became assistant to William Clift (whose daughter Owen married in 1835), Conservator to the Hunterian Museum of the Royal College of Surgeons. It was here that he became acquainted with Cuvier, at whose invitation he visited Paris, and attended his lectures and those of Geoffroy St. Hilaire. The publication, in 1832, of the "Memoir on the Pearly Nautilus" placed the author "in the front rank of anatomical monographers." On Clift's retirement, Owen became sole Conservator to the Hunterian Museum, and was made first Hunterian Professor of Comparative Anatomy and Physiology at the Royal College of Surgeons. In 1856 he accepted the post of Superintendent of the Natural History department of the British Museum, and shortly after his appointment he strongly urged the establishment of a National Museum of Natural History, a project which was eventually carried into effect in 1875. In 1884 he was gazetted K.C.B. Owen was a strong opponent of Darwin's views, and contributed a bitter and anonymous article on the "Origin of Species" to the "Edinburgh Review" of 1860. The position of Owen in the history of anatomical science has been dealt with by Huxley in an essay incorporated in the "Life of Richard Owen," by his grandson, the Rev. Richard Owen (2 volumes, London, 1894). Huxley pays a high tribute to Owen's industry and ability: "During more than half a century Owen's industry remained unabated; and whether we consider the quality or the quantity of the work done, or the wide range of his labours, I doubt if, in the long annals of anatomy, more is to be placed to the credit of any single worker." The record of his work is "enough, and more than enough, to justify the high place in the scientific world which Owen so long occupied. If I mistake not, the historian of comparative anatomy and palaeontology will always assign to Owen a place next to, and hardly lower than, that of Cuvier, who was practically the creator of those sciences in their modern shape, and whose works must always remain models of excellence in their kind." On the other hand, Owen's contributions to philosophical anatomy are on a much lower plane; hardly any of his speculations in this field have stood the test of investigation: "...I am not sure that any one but the historian of anatomical science is ever likely to recur to them, and considering Owen's great capacity, extensive learning, and tireless industry, that seems a singular result of years of strenuous labour." -address at Leeds (British Association, 1858) by. -admission of descent of species. -articles by. -on a badger of Pliocene age. -on the brain. -Mrs. Carlyle's impression of. -and Hooker. -conduct towards Huxley. -Darwin abused by. -on Darwin and Maillet. -and Darwinism. -on ephemeral influence of the "Origin." -Falconer and. -Huxley on. -on Huxley's election to the Athenaeum. -ignores Darwin's work. -influence of. -isolation among scientific men. -lecture on birds by. -letters to. -letter to the "Athenaeum." -"Life of." -on lowness of animals. -on Macacus. -on mammals of Old World. -on morphology of vertebrata. -review in the "Quarterly" of the "Origin." -"Palaeontology" by. -on parthenogenesis. -review in the "Edinburgh Review" by. -on simple and multiple organs. -on use and disuse. -and Bishop Wilberforce's review. -visits Down. -attack on Darwin in his "Anatomy of Vertebrata." -attitude towards Natural Selection. -mentioned. Owls and hawks, as agents in seed-dispersal. Oxalis, bulbils of. -cleistogamic flowers of. -dimorphism of. -pollen-tubes of. -seeds of. -trimorphism of. -O. acetosella, sensitive leaves of. -variation in length of pistil and stamens. -O. sensitiva, Darwin's work on. -O. corniculata, variation of. Oxford, meeting of the British Association at (1847). -Tuckwell's reminiscences of. Oxlips, Darwin's experiment on cowslips, primroses, and. -Darwin on hybrid character of. -scarcity of. Oxyspora paniculata, Wallich on. Pachira, inequality of cotyledons. -P. aquatica. Pacific Ocean, Darwin wishes Hooker to investigate floras of. -islands of the. -coral reefs of. Packard's "Lamarck the Founder of Evolution." Paget, Sir J., on regeneration. -address on elemental pathology. -illness of. -on influence of mind on nutrition. -"Lectures on Surgical Pathology." -letters to. -mentioned. Pairing, in birds. -vigour of birds and effect on time of. Palaeolithic flints, in gravels near Southampton. Palaeontology, rapid progress of. Palaeozoic period. Paley, idea of interference of Creator in construction of each species due to. "Pall Mall," article on "Dr. Hooker on Religion and Science" in. -letter to editor of. Pallas, Darwin's conviction of truth of doctrine of. -doctrine of. -on hybrids and fertility. Palm, Malayan climbing. Palm, L.H., work on climbing plants by. Palma, crater of. Pampas, geology of the. -formation of. -Lyell on Mississippi beds and. -D'Orbigny's theory of formation of. -thistle of the. Pangenesis, adverse opinion on. -Bentham on. -Berkeley on. -bud-propagation and. -Darwin on. -Darwin's suggestion as to term. -difference between Galton's theory of heredity and. -evidence from hybridisation in favour of. -Hooker on. -Huxley's views on. -Jager on. -Lyell on. -and molecular hypothesis of Hackel. -Ranyard on. -Romanes on. -self-fertilisation and. -Wallace on. -the idea a relief to Darwin as connecting facts. -F. Muller and. -bearing on regeneration. -"will turn out true some day." -mentioned. Panmixia. Panniculus carnosus in man. Papilio Memnon, Wallace on. -P. nireus, Mrs. Barber on. -P. pammon, Wallace on. Papilionaceaous flowers, absence in New Zealand. -and hermaphroditism. Papilionidae, Wallace on Malayan. Paraheliotropism, Muller's observations on. -in Phyllanthus. Parallel Roads of Glen Roy (see Glen Roy). Parana, Darwin finds Mastodon at. Pararge, breeding in confinement. Parasites, and degeneration. -extermination of game by. -bloom as protection against. -and galls. Parietaria, explosive stamens of. Parrots, as agents in seed-dispersal. Parsimony, Hamilton's law of. Parthenogenesis, Darwin on. -Owen's Hunterian lecture on. -in Primula. -J. Scott's work on. Partridges, as agents of seed-dispersal. -rudimentary spurs on legs of. Parus caeruleus, protective colouring of. Passiflora, bloom experiments on. -Lord Farrer's work on. -position of flowers of. -Muller assists Lord Farrer in work on. -Scott's work on. -self-sterility of. -Sprengel on. -visited by humming-birds. -P. gracilis, dispersal of seeds. -P. princeps, adapted to humming birds. Patagonia, L. Agassiz on elevation of. -Darwin on geology of. -gigantic land-sloth of. -Admiral Sulivan on. Pathology, Paget's lectures on. Pattison, Mark. Pavo nigripennis. Payne, on effect of rain on plants. -observations by. Peaches, bud-variation in. -raised from seed. Peacock, evolution and Sexual Selection of. -experiments on cutting tail of male. -muscles of tail of. Pearson, H.H.W., on the botany of Ceylon patanas. Peas, course of vessels in ovary of sweet-. -crossing in. -fertilisation of. -waxy secretion in. Pecten, P. latissimus. Pelargonium, peloric. -Beaton on. -Darwin's experiments on. -flowers of. -P. multiflora alba, Darwin's experiments on crossing. Pelobius, Darwin on. Peloria, effect of pollen on regular flowers. -Darwin suggests experiments on. -Masters on. -in Pelargonium. -inheritance of. Peneus, F. Muller on. Pentateuch, N. Lewy on. Periodicals, Darwin's opinion of scientific. -foreign compared with English. Peripatus, Moseley's work on. Peristylus viridis, Lord Farrer's observations on. Permanence of ocean basins. Permian period, glacial action during. -freshwater beds in India. "Personal Narrative," Humboldt's. Peru, anarchy in. -Darwin on terraces in. -D. Forbes on geology of. Peuquenes Pass, Darwin visits. Pfeffer, Prof., on chemotaxis. -considers Wiesner wrong in some of his interpretations. -on Drosera. -"Periodische Bewegungen." Pfitzer, on classification of orchids. Pfluger. Phalaenopsis. Phanerogams, comparison with one class of animals rather than with one kingdom. Phaseoli, crossing in. Phaseolus vulgaris, sleep-movements of. Pheasants, display of colour by golden. -Hewitt on hybrids of. -hybrids between fowls and. -protective colouring. Phillips, J., defines species. -evolutionary views. -"Life on the Earth." -mentioned. Phillips-Jodrell, T.T., founder of Jodrell Laboratory at Kew. Philosophical Club. Philosophical experiments, few naturalists care for. Philosophising, means and laws of. Phlox, Darwin's observations on flowers of. -heterostylism of. -P. Drummondii. -P. subulata. Phyllanthus, F. Muller's paper in "Kosmos" on. -sleep-movements of. -P. Niruri, sleep-movements of. Phryma, de Candolle on. -occurrence in N. America. Phyllotaxis, Darwin and Falconer on. Physical conditions, effect of. "Physical Geography," Herschel's. Physicists, disagree as to rate of cooling of earth's crust. "Physiological Aesthetics," Grant Allen's. Physiological germs. Physiological selection, Romanes'. Physiological species, Huxley's term. Physiological units, Herbert Spencer's. Physiological variations. "Physiology," Huxley's "Elementary Lessons in." -Darwin on difficulty of. -Darwin's want of knowledge of. -Darwin's work on plant-. -England behind in vegetable. -small knowledge of ordinary doctors of. -and vivisection. Phytophagic varieties, Walsh on. Phytophthora, potatoes and. "Pickwick," quotation from. Pictet, on the succession of forms. -mentioned. Pictet and Humbert, on fossil fishes of Lebanon. Pieris, breeding in confinement. -colour the result of mimicry. -protective colouring. -P. napi. -Weismann on. Pigeons, breeding of. -drawings of. -experiments on crossing. -experiments bearing on direct action. -production of varieties. -reduction of wings. -and sterility. -Tegetmeier's work on. -Wallace on Malayan. -Darwin's work on. -experiments in painting. -Flourens' experiments on. -gay deceiver. -pairing for whole life. (Barbs.) (Carriers.) (Fantails.) (Laugher.) (Pouters.) (Rock.) (Runts.) (Tumblers.) Pigs, crossing of. "Pikermi," Gaudry's "Animaux fossiles de." Pinguicula, Darwin's observations on. Pistyll Rhiadr. Pisum, cross-fertilisation of. -P. sativum, visited by Bombus. Pithecoid man, Huxley's term. Pithecus, Owen on Homo and. Placentata. Plagiaulax, Falconer on. Planaria. Planorbis, Hyatt on genesis of species of. -P. multiformis, graduated forms of. Plantago, Ludwig's observations on. -Darwin on. Plants, change in animals compared with change in. -comparison between high and low as regards resistance to injurious conditions. -contractility of. -difference between animals and. -distribution of. -fossil. -of Madeira. -morphological characters. -resemblance to animals. -Saporta's work on fossil. -small proportion preserved as fossils. -splendid for helping belief in Natural Selection. -thorns in. -wide range as compared with animals. -Darwin's interest in movements of. -Darwin on physiology of. -disease in. -effect of stimuli on. Plas Edwards. Plasmodiophora, action on cruciferous roots. Platanthera, H. Muller on. Plato, comparison between plants and man in his "Timaeus." Platysma myoides, contraction during terror. -Darwin's error concerning. Playfair, Lord. Pleistocene Antarctic land, plants derived from. Pliocene, Falconer on mammal from the. Plovers, protective colouring of. Plumage, immature and adult. Plumbago, Darwin's experiments on. -said to be dimorphic. Podostemaceae, fertilisation of. Poisons, natives of Australia injured by vegetable. -absorption by roots of. -effect of injection into plants. Polar bear, modification of. Polar ice-cap, Darwin on the. Polarity, E. Forbes' theory of. Pollen, direct action of. -experiments on. -time of maturity in Eucalyptus and Mimosa. -mechanism for distribution in Martha. -Miyoshi's experiments on tubes of. Polyanthus, crossing in. Polyborus Novae Zelandiae, in Falkland Islands. Polydactylism, and inheritance. Polyembryony, in Coffea and Pachira. Polygala. -P. vulgaris, variation of. Polygamy, in birds. -in Machetes. Polygonum, germination of seeds found in sandpit. Polymorphism, Darwin and Hooker on. -Wallace on. Polytypic genera, variation of. Pontederia, heterostylism of. Pontodrilus, Lankester on. Poplar, Heer on fossil species. Popper, J., letter to. Poppig, on civilisation and savagery. Poppy (corn-), indigenous in Sicily. Porpoises, Flower on. -freshwater. -Murray on. Portillo Pass. Porto-Santo, land-snails of. -plants of. Positivism, Huxley's article in "Fortnightly Review" on. Posoqueria, F. Muller's paper on. Potatoes, crossing experiments. -cultivated and wild. -disease of. -experiments suggested. -graft-hybrids. -sterility and variability in. -Torbitt's experiments on. -Traill's experiments. -varieties of. -Darwin's work on varieties of. -Hildebrand's experiments on. Poulton, Prof., on Prichard as an evolutionist. -"Charles Darwin and the Theory of Natural Selection." Poultry, skulls of. -Tegetmeier's book on. -experiments on colour and sexual selection. Powell, Prof. Baden. "Power of Movement in Plants," Darwin's account of capacity of revolving in plants, in his book. -Continental opinion of. -Wiesner's criticism of. Prawns, F. Muller on metamorphosis of. Prayer, Galton's article on. Pre-Cambrian rocks, Hicks on. Predominant forms. "Prehistoric Europe," J. Geikie's. "Prehistoric Times," Lord Avebury's. Preordination, speculation as to. Prepotency of pollen. Prescott, reference to work by. Preservation, suggested as an alternative term for Natural Selection. Pressure, effect on liquefaction by heat. Preston, S. Tolver, letter to. Prestwich, Prof. J., letter to. -on Parallel Roads of Glen Roy. -on superficial deposits of S. England. -work on Tertiaries. -mentioned. Prevost, C., as candidate for Royal Society Foreign List. -mentioned. Price, J., extract from letter from Darwin to. Prichard, James Cowles (1786-1848): He came on both sides from Quaker families, but, according to the "Encyclopaedia Britannica," he ultimately joined the Church of England. He was a M.D. of Edinburgh, and by diploma of Oxford. He was for a year at Trinity College, Cambridge, and afterwards at St. John's and New College, Oxford, but did not graduate at either University. He practised medicine, and was Physician to the Infirmary at Bristol. Three years before his death he was made a Commissioner in Lunacy. He not only wrote much on Ethnology, but also made sound contributions to the science of language and on medical subjects. His treatise on insanity was remarkable for his advanced views on "moral insanity." -on immutability. -quotations from his "Physical History of Mankind." Priestley, "Green matter" of. -Huxley's essay on. Primogeniture, antagonistic to Natural Selection. Primrose (see also Primula), Darwin's experiments on cowslip and. -dimorphism of. -J. Scott on. Primula, Darwin's work on. -difficulty of experimenting with. -dimorphism of. -dimorphism lost by variation. -entrance of pollen-tubes at chalaza. -varying fertility of. -fertilisation of. -homomorphic unions and. -ovules of. -J. Scott's work on. -stamens of. -P. elatior. -P. longiflora, non-dimorphism of. -Treviranus on. -P. mollis. -P. scotica. -P. sinensis. -fertility of. -legitimate and illegitimate unions. -movement of cotyledons. Principle of divergence. "Principles of Biology," Spencer's. "Principles of Geology," Lyell's. -Darwin on. -Wallace's review of. Pringlea antiscorbutica (Kerguelen cabbage). Priority, Falconer and Owen on. Proboscidean group, extinction of. Progress, in forms of life and organisation. Progression, tendency in organisms towards. Progressive development. Pronuba, the Yucca moth, Riley on. Proteaceae, former extension of. Protean genera, list of N. American. Protection, colour in butterflies and. -thorns as. -Wallace on. -colour and. -colour of birds and. -colour of caterpillars and. -colour of shells and. -Darwin's views on Sexual Selection and. -evolution of colour and. -mimicry and. -monkeys' manes as. -Wallace on colour and. -Wallace on wings of lepidoptera and. Protective resemblance, Wallace on. Proterogyny, in Plantago. Prothero, G.W. Protococcus. Protozoa. Providential arrangement. Prunus laurocerasus, extra-floral nectaries visited by ants. Psithyrus. Psychology, Delboeuf on. -Romanes' work on comparative. Ptarmigan, protective colouring of. Pterophorus periscelidactylus. Publishing, over-readiness of most men in. Pumilio argyrolepis, Darwin on seeds of. Purbeck, Plagiaulax from the. Purpose, Darwin on use of term. Pyrola, fertilisation mechanism in. Quagga, hybrid between horse and. Quails, seed-dispersal by migratory. "Quarterly Journal of Science," article on Darwin and his teaching in. -review by Wallace of the Duke of Argyll's "Reign of Law." "Quarterly Review," Mivart's article. -Bishop Wilberforce's review of "Origin" in. -article on zebras, horses, and hybrids. Quartz, segregation in foliated rocks. Quatrefages, Jean Louis Armand de, de Breau (1810-92): was a scion of an ancient family originally settled at Breau, in the Cevennes. His work was largely anthropological, and in his writings and lectures he always combated evolutionary ideas. Nevertheless he had a strong personal respect for Darwin, and was active in obtaining his election at the Institut. For details of his life and work see "A la Memoire de J.L.A. de Quatrefages de Breau," 4o, Paris (privately printed); also "L'Anthropologie," III., 1892, page 2. -letters to. -translation of paper by. -on proportion of sexes in Bombyx. Quenstedt, work on the Lias by. Queries on expression. Rabbits, Angora, skeletons of. -Darwin's work on. Race, nature's regard for. Racehorse, selection by man. -Wallace on fleetness of. -equality of sexes in. Races of man. -causes of difference in. -Wallace on. Rafflesia, parasites allied to. Rain, effect on leaves. -movements of leaves as means of shooting off. Ramsay, Sir A.C., on origin of lakes. -Geological Society hesitates to publish his paper on Lakes. -on ice-action. -on insects in tropics. -memoir by Geikie of. -on denudation and earth-movements. -overestimates subaerial denudation. -on Parallel Roads of Glen Roy. -on Permian glaciers. -proposal that he should investigate glacial deposits in S. America. -mentioned. Range, De Candolle on large families and their. -coleoptera and restricted. -of genera. -of shells. -size of genera in relation to species and their. -of species. Ranunculaceae, evidence of highness in. Ranunculus auricomus. Ranyard, A.C., letter to "Nature" on pangenesis. Raoul Island, Hooker on. Raphael's Madonna, referred to by Darwin. Raspberry, germination of seeds from a barrow. -waxy secretion of. Rattlesnake, Wright on uses of rattle of. Raven, said to pair for whole life. Ray Society, work of. Raymond, Du Bois, work on plants. Reade, T.M., letters to. -on age of the world. "Reader," sold to the Anthropological Society. Reading, Darwin complains of lack of time for. -little time given by scientific workers to. Reciprocal crosses, half-sterility of. Rede Lecture, by Phillips (1860). Reduction, cessation of selection as cause of. -organs of flight and. -wings of ostrich and. References, Darwin on importance of giving. -Wallace on. Regeneration, power of. -reference in "Variation of Animals and Plants" to. "Reign of Law," the Duke of Argyll's. -reviewed by Wallace. Reindeer, of Spitzbergen. -horns of. Religion and science. Representative species. -in floras of Japan and N. America. -in Galapagos Islands. Reproduction, difference in amount of energy expended by male and female in. Reproductive organs, St.-Hilaire's view of affaiblissement and development of. -in relation to theoretical questions. Research, Huxley and. -justification of. Reseda lutea, sterile with own pollen. -R. odorata, experiment on cross-and self-fertilisation. Resemblance, mimetic. Resignation, expression in. Restiaceae, former extension of. Restricted distribution. Retardation, Cope on. Retrogression. Reversion, in ammonites. -Darwin on. -and degeneration of characters. -factors causing. -hybridism and. -Lord Morton's mare and. -stripes of mules due to. -struggle between Natural Selection and. -and crossing. -peloria and. Review of the "Descent of Man," by J. Morley. Reviews, Darwin on an author writing his own. -on the "Origin of Species," by Asa Gray. -Haughton. -Hopkins. -Hutton. -Huxley. -F. Jenkin. -Owen. -Wilberforce. Rhamnus. Rhexia, flowers of. -R. virginica, W.H. Leggett on anthers. Rhinoceros. Rhinochetus. Rhizocephala, retrograde development in. Rhododendron Boothii. Rhopalocera, breeding in confinement. Rhynchoea, colour of. Rich, Anthony (1804?-1891): Educated at Caius College, Cambridge, of which he was afterwards an Honorary Fellow. Author of "Illustrated Companion to the Latin Dictionary and Greek Lexicon," 1849, said to be a useful book on classical antiquities. Mr. Darwin made his acquaintance in a curious way--namely, by Mr. Rich writing to inform him that he intended to leave him his fortune, in token of his admiration for his work. Mr. Rich was the survivor, but left his property to Mr. Darwin's children, with the exception of his house at Worthing, bequeathed to Mr. Huxley. -legacy to Huxley. -letter to. -leaves his fortune to Darwin. Rich, Mrs., mentioned. Richardson, R., on tablet to commemorate Darwin's lodgings at 11, Lothian Street, Edinburgh. Richardson, Darwin on merits of. Rigaud, on formation of coal. Riley, Charles Valentine (1843-95): was born in England: at the age of seventeen he ran away from home and settled in Illinois, where at first he supported himself as a labourer; but he soon took to science, and his first contributions to Entomology appeared in 1863. He became entomological editor of the "Prairie Farmer" (Chicago), and came under the influence of B.D. Walsh. In 1868 Riley became State Entomologist of Missouri, and in 1878 Entomologist to the U.S. Department of Agriculture, a post he resigned in 1894 owing to ill-health; his death was the result of a bicycle accident. (Taken principally from the "Proceedings of the Entomological Society of Washington," Volume III., 1893-6, page 293.) -letters to. -mentioned. Rio Janeiro, absence of erratic boulders near. -Agassiz on drift-formation near. Rio Negro. Rio Plata. Ritchie, Mrs., visit to Down. Rivers, The late Mr. Thomas: of Sawbridgeworth, was an eminent horticulturist and writer on horticulture. -letters to. Robin, attracted by colour of Triphaena (Triphoea). Robinia, insect visitors of. Rocks, bending when heated. -condition in interior of earth. -fluidity of. -metamorphism of (see also Metamorphism). Rocky Mountains, wingless insects of the. Rogers, W.B. and H.D., on cleavage. -on coalfields of N. America. -on parallelism of axis-planes of elevation and cleavage. Rolleston, George (1829-81): obtained a first-class in Classics at Oxford in 1850; he was elected Fellow of Pembroke College in 1851, and in the same year he entered St. Bartholomew's Hospital. Towards the close of the Crimean War, Rolleston was appointed one of the Physicians to the British civil hospital at Smyrna. In 1860 he was elected the first Linacre Professor of Anatomy and Physiology, a post which he held until his death. "He was perhaps the last of a school of English natural historians or biologists in the widest sense of the term." In 1862 he gave the results of his work on the classification of brains in a lecture delivered at the Royal Institution, and in 1870 published his best known book, "Forms of Animal Life (Dict. Nat. Biography). -address in "Nature" by. -on the orang-utang. -adhesion to Darwin's views. -letter to. -letter to Darwin from. -mentioned. Rollisson. Roman villa at Abinger. Romanes, G.J. (1848-94): was one of Mr. Darwin's most devoted disciples. The letters published in Mrs. Romanes' interesting "Life and Letters" of her husband (1896) make clear the warm feelings of regard and respect which Darwin entertained for his correspondent. -Darwin on controversy between Duke of Argyll and. -on graft-hybrids. -letters to. -letter to Darwin from. -letter to "Nature" in reply to the Duke of Argyll. -on physiological selection. -review of Roux's book. -on heliotropism. -lecture on animal intelligence by. -lecture on evolution of nerves. -letter to "Times" from. -"Life and Letters" of. -on minds of animals. Roots, heliotropism of. -sensitive tip of. Roses, N. American species. -bud-variation. -raising from seed. -resemblance of seedling moss-rose to Scotch. -varieties of. Ross, Sir J. Rosse, Lord. Round Island, fauna and flora of. Roux's "Struggle of Parts in the Organism." Royal Commission on Vivisection. Royal Institution, lectures at. Royal medals. Royal Society, council meeting of. Royer, Mdlle., translatress of the "Origin." Royle, John Forbes (1800-58): was originally a surgeon in the H.E.I.C. Medical Service, and was for some years Curator at Saharunpur. From 1837- 56 he was Professor of Materia Medica at King's College, London. He wrote principally on economic and Indian botany. One of his chief works was "Illustrations of the Botany and other branches of the Natural History of the Himalayan Mountains and of the Flora of Cashmere." (London, 1839.) -letters to. -mentioned. Rubiaceae, dimorphism in. -fertilisation in. Rubus, N. American species. -variation in. -F. Darwin on roots of. Rubus and Hieracium, comparison of variability of N. American and European species. Rucker. Rudimentary organs. -in frogs. -nascent and. -variation of. -in man. -use in classification. Rudinger, Dr., on regeneration. Rue, flowers of. Ruffs, polygamy of. Rumex, germination of old seeds. Russia, forms of wheat cultivated in. Rutaceae, A. St.-Hilaire on difference in ovary of same plants of. Sabine, General Sir E. Sabine (1788-1883): President of the Royal Society 1861-71. (See "Life and Letters," III., page 28.) -address to Royal Society. -award of Copley medal to Darwin during presidency of. -recognition by Government. -mentioned. Sabrina, elevation of. Sagitta. St. Dabeoc's heath, in Azores. St. Helena, Darwin suggests possibility of finding lost plants in earth from. -extinction in. -Hooker on flora of. -land-birds of. -plants of. -trees of. -Darwin on craters of. -geology of. -subsidence in. -White on hemiptera of. St.-Hilaire, A.F.C.P. de, on affaiblissement. -erect and suspended ovules in same ovary. -"Lecons de Botanique." -Life of. St.-Hilaire, J.G., on monstrosities. -author of "Life of A.F.C.P. de St.-Hilaire." St. Jago, Darwin on craters of. -elevation of. St. Paul's rocks, plants of. -geological structure. Saintpaulia, dimorphic flowers. St. Ventanao, conglomerates of. Salicaceae. Salicornia, bloom on. Salix, varieties of. Salsola Kali, bloom on. Salt water, effect on plants. Salter, on vitality of seeds after immersion in the sea. Saltus, Darwin's views on. Salvages, flora of the. Salvia, Hildebrand's paper on. Samara, Russian wheat sent to Darwin from. Samoyedes, power of finding their way in fog. Sandberger, controversy with Hilgendorf. Sanderson, Sir J.B., electrical experiments on plants. -letters to. -on vivisection. Sandwich Islands, absence of Alpine floras. -flora of. -Geranium of. -Dana on valleys and craters. -Galapagos and. Sanicula, occurrence of species in Azores. -range of. Santa Cruz. Santorin, crater of. -linear vent in. -Lyell's account of. Saporta, Marquis de, (1823-95): devoted himself to the study of fossil plants, and by his untiring energy and broad scientific treatment of the subject he will always rank as one of the pioneers of Vegetable Palaeontology. In addition to many important monographs on Tertiary and Jurassic floras, he published several books and papers in which Darwin's views are applied to the investigation of the records of plant-life furnished by rocks of all ages. ("Le Marquis G. de Saporta, sa Vie et ses Travaux," by R. Zeiller. "Bull. Soc. Geol. France," Volume XXIV., page 197, 1896.) -letters to. -on rapid development of higher plants. Sargassum, Forbes on. Sarracenia. Savages, civilisation of. -comparison between animals and. -decrease of. -Selection among. Saxifrages, destruction in Ireland of Spanish. -formation of hairs in. Saxonika, form of Russian wheat. Scaevola, fertilisation mechanism of. -S. microcarpa, fertilisation mechanism of. Scalesia. Scandinavia, Hooker on potency of flora. -Blytt on distribution of plants of. -elevation of. Scarlet fever, Darwin's dread of. "Scenery of Scotland," Sir A. Geikie's. Scepticism, Darwin on. Schimper, review by Hooker of "Paleontologie Vegetale" by. Schlagintweit. Schleiden, convert to Darwin's views. Schmankewitsch, experiments on Artemia by. Schobl, J., on ears of mice. Schoenherr, C.J. Schomburgk, Sir R., on Catasetum, Monacanthus, and Myanthus. School, Darwin at Mr. Case's. -of Mines. Schrankia, a sensitive species of. Schultze, Max. Science, and superstition. -progresses at railroad speed. Science Defence Association, Darwin asked to be president of. Scientific men, attributes of. -domestic ties and work of. -article in "Reader" on. Scientific periodicals, Darwin's opinion of. Scotland, forest trees of. -comparison between flora of T. del Fuego and that of. -elevation of. -frequency of earthquakes in. -land-glaciation of. -tails of diluvium in. "Scotsman," Forbes' lecture published in. -Darwin's letter on the Parallel Roads of Glen Roy in the. Scott, D.H., obituary notice of Nageli by. Scott, John (1838-80): Short obituary notices of Scott appeared in the "Journal of Botany," 1880, page 224, and in the "Transactions of the Bot. Soc. of Edinburgh" Volume XIV., November 11th, 1880, page 160; but the materials for a biographical sketch are unfortunately scanty. He was the son of a farmer, and was born at Denholm (the birthplace the poet Leiden, to whom a monument has been erected in the public square of the village), in Roxburghshire. At four years of age he was left an orphan, and was brought up in his aunt's household. He early showed a love of plants, and this was encouraged by his cousin, the Rev. James Duncan. Scott told Darwin that he chose a gardening life as the best way of following science; and this is the more remarkable inasmuch as he was apprenticed at fourteen years of age. He afterwards (apparently in 1859) entered the Royal Botanic Garden at Edinburgh, and became head of the propagating department under Mr. McNab. His earliest publication, as far as we are aware, is a paper on Fern-spores, read before the Bot. Soc., Edinburgh, on June 12th, 1862. In the same year he was at work on orchids, and this led to his connection with Darwin, to whom he wrote in November 1862. In 1864 he got an appointment at the Calcutta Botanic Garden, a position he owed to Sir J.D. Hooker, who was doubtless influenced by Darwin's high opinion of Scott. It was on his way to India that Scott had, we believe, his only personal interview with Darwin. We are indebted to Sir George King for the interesting notes given below, which enable us to form an estimate of Scott's personality. He was evidently of a proud and sensitive nature, and that his manner was pleasing and dignified appears from Darwin's brief mention of the interview. He must have been almost morbidly modest, for Darwin wrote to Hooker (January 24th, 1864): "Remember my URGENT wish to be able to send the poor fellow a word of praise from any one. I have had hard work to get him to allow me to send the [Primula] paper to the Linn. Soc., even after it was written out!" And this was after the obviously genuine appreciation of the paper given in Darwin's letters. Sir George King writes:-- "He had taught himself a little Latin and a good deal of French, and he had read a good deal of English literature. He was certainly one of the most remarkable self-taught men I ever met, and I often regret that I did not see more of him...Scott's manner was shy and modest almost to being apologetic; and the condition of nervous tension in which he seemed to live was indicated by frequent nervous gestures with his hands and by the restless twisting of his long beard in which he continuously indulged. He was grave and reserved; but when he became interested in any matter he talked freely, although always deliberately, and he was always ready to deafen his opinions with much spirit. He had, moreover, a considerable sense of humour. What struck me most about Scott was the great acuteness of his powers of observing natural phenomena, and especially of such as had any bearing on variation, natural selection or hybridity. While most attentive to the ordinary duties of the chief of a large garden, Scott always continued to find leisure for private study, and especially for the conduct of experiments in hybridization. For the latter his position in the Calcutta garden afforded him many facilities. After obtaining a post in the Calcutta Botanic Gardens, Scott continued to work and to correspond with Darwin, but his work was hardly on a level with the promise of his earlier years. According to the "Journal of Botany," he was attacked by an affection of the spleen at Darjeeling, where he had been sent to report on the coffee disease. He returned to Edinburgh in the spring of 1880, and died in the June of that year. At the time of his death many experiments were in hand, but his records of these were too imperfect to admit of their being taken up and continued after his death. In temper Scott was most gentle and loveable, and to his friends he was loyal almost to a fault. He was quite without ambition to 'get on' in the world; he had no low or mean motives; and than John Scott, Natural Science probably had no more earnest and single-minded devotee." -correspondence with. -criticism on the "Origin" by. -letters to. -on Natural Selection. -on a red cowslip. -confirms Darwin's work, also points out error. -Darwin assists financially. -Darwin's opinion of. -Darwin offers to present books to. -Darwin writes to Hooker about Indian appointment for. -Darwin's proposal that he should work at Down as his assistant. -Darwin suggests that he should work at Kew. -on dispersal of seed of Adenanthera by parrots. -on fertilisation of Acropera. -a good observer and experimentalist. -a lover of Natural History. -observations on acclimatisation of seeds. -on Oncidium flexuosum. -letter to Darwin from. -offered associateship of Linnean Society. -on Imatophyllum. -on self-sterility in Passiflora. -on Primula. -on sexes in Zea. -mentioned. Scrope, P., on volcanic rocks. Scrophularineae. Scudder, on fossil insects. Sea, Dana underestimates power of. -changes in level of land due to those of. -marks left on land by action of. Seakale, bloom on. Seashore plants, use of bloom on. Sea-sickness, Darwin suffers from. "Seasons with the Sea Horses," Lamont's. Secondary period, abundance of Araucarias and Marsupials during. -equality of elevation in British rocks of. -insects prior to. Sections of earth's crust, need for accurate. Sedgwick, Prof. A., extract from letter to Owen from. -letter to Darwin from. -on the "Vestiges of Creation." -and the Philosophical Society's meeting at Cambridge. -and the "Spectator." -Darwin's visit to. -Feelings towards Darwin. -on the structure of large mineral masses. -proposes Forbes for Royal medal. -quotation from letter to Darwin from. -suggested as candidate for Royal medal. -mentioned. Sedgwick, A., address at the British Association (1899). Sedimentary strata, conversion into schists. Sedimentation, connection with elevation and subsidence. -near coast-lines. Seedlings, sensitiveness to light. Seeds, collected by girls in Prof. Henslow's parish. -dispersal of. -effect of immersion on. -of furze. -Asa Gray on Darwin's salt-water experiments. -germination after 21 1/2 hours in owl's stomach. -moss-roses raised from. -peaches from. -variation in. -bright colours of fruits and. -difficulty of finding in samples of earth. -dormant state of. -germination from pond mud. -Hildebrand on dispersal of. -mucus emitted by. -stored by ants. -supposed vivification of fossil. -vitality of. Seeley, Prof. Seemann, on commingling of temperate and tropical plants in mountains of Panama. -on the "Origin" in Germany. -mentioned. Segregation of minerals in foliated rocks. Selaginella, foot of, compared with organ in Welwitschia seedling. Selection, a misleading term. -artificial. -as means of improving breeds. -importance of. -influence of speedy. -utilised by pigeon-fanciers. -Sexual (see Sexual Selection). -sterility and. -unconscious. -and variation. -voluntary. -and inheritance. Self-fertilisation, abundance of seeds from. -Darwin's experiments on cross- and. -evil results of. -comparison between seeds from cross- and. -in Goodeniaceae. -in Orchids. Self-interest, Preston on. Self-sterility, in Eschscholtzia. -in plants. -connection with unnatural conditions. Selliera, Hamilton on fertilisation-mechanism. Semper, Karl (1832-93): Professor of Zoology at Wurzburg. He is known for his book of travels in the Philippine and Pelew Islands, for his work in comparative embryology, and for the work mentioned in the above letter. See an obituary notice in "Nature," July 20th, 1893, page 271. -letter to. Senecio. -S. vulgaris, profits by cross-fertilisation. Sensitive plants, Darwin's work on. Sensitiveness, diversified kinds in allied plants. Separate creations, Darwin on. Sequoia. Seringe, on Aconitum flowers. Sertularia. Sethia, dimorphism of. Settegast, H., letter to. Severn, Darwin on floods of. Seward, A.C., "Fossil Plants as Tests of Climate." Sexes, colour, and difference in. -proportion at birth. -proportion in animals. Sexual likeness, secondary. Sexual organs, as collectors of generative elements. -appendages in insects complemental to. Sexual reproduction, Galton on. -bearing of F. Muller's work on essence of. Sexual Selection, Bates on. -Darwin on. -article in "Kosmos" on. -colour and. -man and. -in moths and butterflies. -subordinate to Natural Selection. -Wallace on colour and. -Wallace on difficulties of. Sexuality, Bentham on. -in lower forms. -origin of. Shanghai, tooth of Mastodon from. Sharp, David, on Bombus. -on Volucella. -"Insects." Sharpe, Daniel (1806-56): left school at the age of sixteen, and became a clerk in the service of a Portuguese merchant. At the age of twenty-four he went for a year to Portugal, and afterwards spent a considerable amount of time in that country. The results of his geological work, carried out in the intervals of business, were published in the Journal of the Geological Society of London ("Quart. Journ. Geol. Soc." Volume V., page 142; Volume VI., page 135). Although actively engaged in business all his life, Sharpe communicated several papers to the Geological Society, his researches into the origin of slaty cleavage being among the ablest and most important of his contributions to geology ("Quart. Journ. Geol. Soc." Volume III., page 74; Volume V., page 111). A full account of Sharpe's work is given in an abituary notice published in the "Quart. Journ. Geol. Soc." Volume XIII., page xlv. -on elevation. -Darwin meets. -letters to. -on cleavage and foliation. Sharpey, W., letter from Falconer to. -Honorary member of Physiological Society. Shaw, J., letter to. Sheep, varieties of. Sheldrake, dancing on sand to make sea-worms come out. Shells, Forbes and Hancock on British. -distorted by cleavage. -means of dispersal. -protective colour of. Sherborn, C.D., "Catalogue of Mammalia" by A.S. Woodward and. Shetland, comparison between flora of T. del Fuego and that of. Shrewsbury, school. Siberia, Rhinoceros and steppes of central. Sicily, elephants of. -flora of. Sidgwick, Prof. H. Siebold, von. Sigillaria, an aquatic plant. Silene, Gartner's crossing-experiments on. Silurian, comparison between recent organisms and. -life of. -Lingula from the. -corals. -volcanic strata. Simon, Sir John: he was for many years medical officer of the Privy Council, and in that capacity issued a well-known series of Reports. -reports by. Simple forms, existence of. -survival of. Simpson, Sir J., on regeneration in womb. Siphocampylus. Sitaris, Lord Avebury on Meloe and. Siwalik hills. Skertchley, S.B.J., on palaeolithic flints in boulder-clay of E. Anglia. -letter to. Skin, influence of mind on eruptions of. Slate, cleavage of schists and. Slave-ants, account in the "Origin" of. Sleep, plants' so-called. Sleep-movements, in plants. -of cotyledons. Slime of seeds. Sloths. Smell, Ogle's work on sense of. Smerinthus populi-ocellatus, Weir on hybrid. Smilaceae, reference to genera of. Smilax, De Candolle on flower of. Smith, Goldwin. Smith, J., note on. Snails of Porto Santo. Snipe, protective colour of. Snow, red. -geological action of frozen. Snowdon, elevation in recent times. Social instincts, actions as result of. Social plants, De Candolle on. -in the U.S.A. "Sociology," H. Spencer's. Soda, nitrate beds. Soil, in relation to plant distribution. Solanaceae. Solanum rostratum, Todd on stamens of. Solenhofen, bird-creature from. Sollas, Prof., director of the Funafuti boring expedition. -account of the boring operations by. Sonchus, introduced into New Zealand. Song, importance in animal kingdom. Sophocles, Prof., on expression of affirmation by Turks. Sorby, on metamorphism. Sound, and music. Southampton, British Association meeting (1846). -Darwin on gravel deposits at. -Darwin's visits to. Spanish chesnut, variation in leaf divergence. Spanish plants in Ireland. -in La Plata. Spawn, dispersal of frogs'. Spean, terraces in valley of. Special ordination. Specialisation. Species, antiquity of plant-. -belief in evolution of. -changing into one another. -creation of. -Darwin recognises difficulties in and objections to his views on. -definition of. -descriptive work influenced by Darwin's views on. -facts from Hooker bearing on. -food as important factor in keeping up number of. -frequency of. -Asa Gray on. -Hooker on. -intermediate forms absent in close. -little tendency during migration to form new. -modification of. -and monstrosities. -mutability of. -Nageli's views on. -origin of (see Origin of Species). -permanence of. -Prichard on meaning of term. -range of. -representative. -separate creation of. -spreading of. -sterility between allied. -and sterility. -time necessary to change. -time of creation of new. -variation of. -Wallace on origin of. -Walsh on modification of. -Weismann on. -Gaudry on affiliation of. -Hackel on change of. -isolation of. -value of careful discrimination of. "Species not transmutable," Bree's book on. Specific character, Falconer on persistence of. Speculation, Darwin on. Spencer, H., Darwin on the advantage of his expression "survival of the fittest." -letter to. -on electric organs. -on genesis of nervous system. -on survival of the fittest. -Romanes on his theory of nerve-genesis. -Wallace's admiration for. -Darwin on his work. -extract from letter to. -mentioned. Spermacoce. Spey, terraces of. Sphagnum, parasitism of orchids on. Spiders, mental powers of. -Moggridge on. Spiranthes, fertilisation of. Spiritualism, Darwin on. Sptizbergen, Lamont's book on. -reindeer of. Sponges, Clark on classification of. -Hackel's work on. -F. Muller on. Spontaneous generation. -Darwin's disbelief in. -Huxley's disbelief in. Sports. Sprengel, (C.C.) Christian Konrad (1750-1816): was for a time Rector of Spandau, near Berlin; but his enthusiasm for Botany led to neglect of parochial duties, and to dismissal from his living. His well-known work, "Das Entdeckte Geheimniss der Natur," was published in 1793. An account of Sprengel was published in "Flora," 1819, by one of his old pupils. See also "Life and Letters," I., page 90, and an article in "Natural Science," Volume II., 1893, by J.C. Willis. -on Passion-flowers. Stag-beetle, forms of. Stahl, Prof., on Desmodium. -on transpiration. Stainton. Stanhope, Lord. Stanhopea, fertilisation of. Stapelia, fertilisation of. Starling, paired three times in one day. State-entomologist, appointment of in America, not likely to occur in England. Statistics, of births and deaths. -Asa Gray's N. American plant-. Steinheim, Lias rocks of. Stellaria media, cross-fertilisation of. Stephens, Miss Catherine: was born in 1794, and died, as the Countess of Essex, in 1882. Sterile, use of term. Sterility, accumulation through Natural Selection. -arguments relating to. -artificial production of. -between allied species aided by Natural Selection. -connection with sexual differentiation. -and crossing. -domestication and loss of. -experiments on. -of hybrids. -in human beings. -Huxley on. -increase of races and. -laws governing. -Natural Selection and. -in pigeons. -in plants (see also self-sterility). -reciprocal crosses and unequal. -selection and. -variations in amount of. -varieties and. Stirling, and Huxley. Stokes, Sir G. Strasburger, on fertilisation of grasses. Stratification, and cleavage. Strephium, vertical position of leaves. Strezlecki. Strickland, H., letters to. -on zoological nomenclature. Stripes, loss and significance of. Structural dissimilarity, and sterility. Structure, external conditions in relation to. Struggle for existence. -and crossing. -factors concerned in. -and hybrids. -J. Scott on. Strychnos, F. Muller on. Student, Darwin as an Edinburgh. Studer, Bernhard: Several of Studer's papers were translated and published in the "Edinburgh New Phil. Journ." See Volume XLII., 1847; Volume XLIV., 1848, etc. -on cleavage and foliation. "Studien zur Descendenz-Theorie," Weismann's. "Studies in the Theory of Descent," Meldola's translation of Weismann's book. "Study of Sociology," H. Spencer's. Stur, Dionys (1827-93): Director of the Austrian Geological Survey from 1885 to 1892; author of many important memoirs on palaeobotanical subjects. Style, Darwin on. -Darwin on Huxley's. -effect of controversy on. Suaeda, bloom on. Submergence. Subsidence, evidence of. -coral reefs and. -and elevation. -equable nature of. -large areas simultaneously affected by. -in oceans. -and sedimentation. -volcanic action. Subterranean animal, existence in Patagonia of supposed. Subularia, fertilisation of. Succession of types. Sudden appearance of organisms, due to absence of fossils in pre- Cambrian rocks. Sudden jumps, modification by. -Darwin's disbelief in. Suess, "Antlitz der Erde." Suffolk Crag, comparison with recent strata. Sugar-cane, Barber on hybrids of. -new varieties of. Sulivan, Admiral, on Patagonia. Superficial deposits, geological nature of. Supernumerary members. -amputation followed by regeneration of. "Survival of the fittest," Darwin on use of the expression. -Wallace on the expression. -sharpness of thorns the result of. -colour of birds and. Swainson, on wide range of genera. Switzerland, Tyndall on valleys of. Sydney. Symonds, William Samuel (1818-87): a member of an old West-country family, was an undergraduate of Christ's College, Cambridge, and in 1845 became Rector of Pendock, Worcestershire. He published in 1858 a book entitled "Stones of the Valley;" in 1859 "Old Bones, or Notes for Young Naturalists;" and in 1872 his best-known work, "Records of the Rocks." Mr. Symonds passed the later years of his life at Sunningdale, the house of his son-in-law, Sir Joseph Hooker. (See "Quart. Journ. Geol. Soc." Volume XLIV., page xliii.) -on imperfection of geological record. Tacsonia, Darwin on flowers of. -fertilisation by humming-birds. -Scott's work on. Tahiti, coral reefs of. -Darwin on. Tails of diluvium, in Scotland. Tait, Prof. P.G., article in "North British Review." -on age of world. Tait, L., letters to. Tait, W.C., letter to. -on rudimentary tails in dogs and Manx cats. -sends Drosophyllum to Darwin. Talbot, Mrs. E., letter to. Tandon, Moquin, "Elements de Teratologie Vegetale." Tankerville, Lord. Tasmania, comparison between floras of New Zealand and. -Hooker's Flora of. -trees of. Taylor, W., "Life and Correspondence" of. Tears, and muscular contraction. Tees, Hooker on glacial moraines in valley of. Tegetmeier, W.B., assistance rendered to Darwin by. -letters to. Telegraph-plant (see also Desmodium). "Telliamed" (de Maillet), evolutionary views of. Tendrils, morphology of. Teneriffe, flora of. -violet of Peak of. -Webb and Humboldt on zones of. Tennent, Sir J.E., on elephants' tears. -on Utricularia. Tentacles, aggregation of protoplasm in cells of plant-. Teodoresco, on effect of excess of CO2 on vegetation. Teratology, Masters on vegetable. -Moquin Tandon on. Terebratula. Termites compared with cleistogamic flowers. -F. Muller's paper on. Terraces, Darwin on Patagonian. Tertiary, Antarctic continent, Darwin on existence of. -Mastodon from Shanghai. -flora in Madeira. Tertiary period, action of sea and earth-movement. -island floras of the. -Saporta's work on plants. -succession of types during the. -Prestwich's work on. Testimonials, Darwin on. Tetrabranchiata, Hyatt on the. Thayer's "Letters of Chauncey Wright." Theologians, Huxley on. Theological articles, by Asa Gray. Theology, Darwin's opinion on. Theorising, observing and. Theory, Darwin's advice to Scott to be sparing in use of. Thibet, Hooker prohibited crossing into. Thierzucht, Settegast's. Thiselton-Dyer, Lady. Thiselton-Dyer, Sir W., assists Darwin in bloom-experiments. -Darwin signs his certificate for Royal Society. -lecture on plant distribution as field for geographical research. -letter to "Nature" from. -notes on letter from Darwin to Bentham. -on partial submergence of Australia. -letters to. -extract from letter to. -on Darwin. Thiselton-Dyer, Sir W., and Prof. Dewar, on immersion of seeds in liquid hydrogen. Thlaspi alpestre, range of. Thompson, Prof. D'Arcy, prefatory note by Darwin to his translation of H. Muller's book. Thompson, W., natural-historian of Ireland. Thomson, Sir W., see Kelvin, Lord. Thomson, Sir Wyville, on Natural Selection. -mentioned. Thomson, review of Jordan's "Diagnoses d'especes" by. Thorns, forms of. "Three Barriers," theological hash of old abuse of Darwin. Thury on sex. Thwaites, Dr. G.H.K. (1811-82): held for some years the post of Director of the Botanic Gardens at Peradenyia, Ceylon; and in 1864 published an important work on the flora of the island, entitled "Enumeratio Plantarum Zeylaniae." -on Ceylon plants. -letters to. -on the "Origin." Thymus. Tieghem, Prof. van, on course of vessels in orchid flowers. -on effect of flashing light on plants. Tierra del Fuego, flora of. -comparison with Glen Roy. -evidence of glaciers in. -micaschists of. Time, and evolutionary changes. -geological. -meaning of millions of years. -Niagara as measure of geological. -rate of deposition as measure of. -Wallace on geological. "Times," article by Huxley in. -letter by Fitz-Roy in. Timiriazeff, Prof. Timor, Mastodon from. Toad, power of Indian species to resist sea-water. Tobacco, Kolreuter on varieties of. Todd, on Solanum rostratum. "Toledoth Adam," title of book on evolution by N. Lewy. Torbitt, J., experiments on potatoes, and letter to. Torquay, Darwin's visit to. Tortoises, conversion of turtles into land-. Tortugas, A. Agassiz on reefs of. Toryism, defence of. Toucans, colour of beaks in breeding season. Trachyte, separation of basalt and. Tragopan. Traill, experiments on grafting. Transfusion experiments, by Galton. Translations of Darwin's books. Transplanting, effect on Alpine plants. Transport, occasional means of. Travels, Bates' book of. -Humboldt's. -Wallace's. Travers, H.H., on Chatham Islands. Trecul, on Drosera. Trees, herbaceous orders and. -occurrence in islands. -older forms more likely to develop into. -Asa Gray on. -conditions in New Zealand favourable to development of. -crossing in. -separate sexes in. Treub, M., on Chalazogamy. Treviranus, Prof., on Primula longiflora. Trifolium resupinatum, Darwin's observations on bloom on leaflets. Trigonecephalus. Trilobites, change of genera and species of. Trimen, on painting butterflies. Trimorphism, in plants. Trinidad, Catasetum of. -Cruger on caprification in. Triphaena (Triphoea) pronuba, robin attracted by colour of. Tristan d'Acunha, Carmichael on. -vegetation of. Triticum repens var. littorum, bloom-experiments on. Trollope, A., quotation by Darwin from. Tropaeolum, Darwin's experiments on. -peloric variety of. -waxy secretion on leaves. Tropical climate, in relation to colouring of insects. Tropical plants, possible existence during cooler period. -retreat of. Tropics, climatic changes in. -description of forests in. -similarity of orders in. Tubocytisus, Kerner on. Tuckwell, on the Oxford British Association meeting (1860). Tucotuco. Tuke, D.H., on influence of mind on body. -letter to. Tulips. Turkey, colour of wings, and courtship. -muscles of tail of. Turner, Sir W., Darwin receives assistance from. -on Darwin's methods of correspondence. -letters to. Turratella. Turtles, conversion into land-tortoises. Tussilago, Darwin on seeds of groundsel and. Twins, Galton's article on. Tylor, article in "Journal of the Royal Institution" by. -on "Early History of Mankind." Tyndall, lack of caution. -lecture by. -on the Alps. -review in the "Athenaeum" of. -on valleys due to glaciers. -work of. -dogmatism of. -on glaciers. -on Sorby's work on cleavage. -mentioned. Typhlops. Typical forms, difficult to select. -vagueness of phrase. Typotherium, Falconer on. Tyrol, Mojsisovics on the Dolomites of the. Umbelliferae, morphological characters of. -difference in seeds from the same flower. Undulation of light, comparison between Darwin's views and the theory of. Ungulates, development in N. America during Tertiary period. United States, flora of. -spread of Darwin's views in. Unity of coloration, Walsh on. Uredo, on Haematoxylon. Ursus arctos, Lamont on. -U. maritimus, Lamont on. Urticaceae. Uruguay. D'Urville, on Canary Islands. Use and disuse. -in plants. Uses, Natural Selection and. Uspallata. Utilitarianism, Darwin on. Utility and inheritance. Utopian "Flora," Darwin's idea of. Utricularia, Darwin's work on. -U. stellaris, Sir E. Tennent on. Vaginulus, Darwin finds new species of. Valeriana, two forms of. Valleys, action of ice in formation of. -Dana on Australian. -Darwin on origin of. Valparaiso. Van Diemen's Land, flora of, in relation to New Zealand. Vanda. Vandeae, structure of ovary. Vanessa, two sexual forms of. -breeding in confinement. -colour of. Vanilla. Variability, backward tendency of. -Bentham on. -causes of. -De Candolle on. -dependent more on nature of organism than on environment. -Huxley and Scott on. -importance of subject of cause of. -Natural Selection and. -in oaks. -greater in bisexual than in unisexual plants. -of ferns "passes all bounds." -greater in male than female. -in ovaries of flowers. -tendency of genera at different periods towards. Variation. -an innate principle. -Bates on. -in blackbirds. -causes of. -centrifugal nature of. -checked by Natural Selection. -climate and. -Darwin attaches importance to useless. -Darwin on favourable. -divergence of. -and external conditions. -in elephants. -in Fucus. -of large genera. -laws of. -of monotypic and polytypic genera. -and monstrosities. -and Natural Selection. -ordination and. -in peaches. -in plants. -produced by crossing. -rate of action of. -of small genera. -sterility advantageous to. -Weismann on. -galls as cause of. -and loss of dimorphism in Primula and Auricula. -Sexual Selection and minute. -transmission to sexes. -Verlot on. -Wallace on. "Variation of Animals and Plants under Domestication," completion of. -delay in publication. -Lyell on. -translation of. -Wallace's opinion of. -Darwin at work on. Varieties, accumulation of. -distinction between species and. -fertility of. -in insects. -in large genera. -of molluscs. -production of. -species the product of long series of. -use of. -Wallace on. -elimination by crossing. -zoologists neglect study of. Vaucher, "Plantes d'Europe." "Vegetable Teratology," Masters'. Vegetative reproduction, Darwin on. Veitch, J. Velleia, fertilisation mechanism of. Verbascum, crossing and varieties in. -Scott's work on. Verbenaceae. Verlot, on variation in flowers. Veronica, Antarctic species of. Vessels, course of, as guide to morphology of flowers. "Vestiges of Creation," Huxley's review of. -the "Origin of Species" and. -Vetch, extra-floral nectaries of. Vetter, editor of "Kosmos." Viburnum lantanoides, in Japan and east U.S.A. Victoria Street Society for Protection of Animals against Vivisection, charge brought against Dr. Ferrier by. Villa Franca, Baron de, on varieties of sugar-cane. Villarsia. Vine, graft-hybrids of. -varieties of. -morphology of tendrils. Viola, ancestral form of. -cleistogamic flowers of. -pollen-tubes of. -Madagascan. -Pyrenean. -on Peak of Teneriffe. -V. canina, fertilisation of. -V. nana. -V. odorata, floral biology of. Virchow, Huxley's criticism of. -publication by Hackel of Darwin's criticism of. Viscum. Vitality of seeds, in salt-water experiments. Viti group of islands, effect of subsidence. Vivisection. Vochting, H., "Bewegung der Bluthen und Fruchte." -letter to. -"Organbildung im Pflanzenreich." "Volcanic Geology," Dana's. Volcanic islands, polymorphic species in. -Darwin's geological observations on. -Darwin's opinion of his book on. -Lyell and Herschel on. -relation to continents. Volcanic phenomena, cause of. -Darwin on. -and elevation. -as mere accidents in swelling up of dome of plutonic rocks. -and subsidence. Volcanic rocks. Volcano, in interior of Asia. Volcanoes, in S. America. -compared with boilers. -maritime position of. -of St. Jago, Mauritius, and St. Helena. -simultaneous activity of. -and subsidence. Volucella, as example of mimicry. Vries, H. de, on plant-movements. Vulcanicity. Wagner, M., attacks Darwin. -essay by. -mentioned. "Wahl der Lebens-Weise." Wahlenberg, on variation of species in U.S.A. Wales, Darwin's visit to. -comparison of valleys of Lochaber and. -Darwin on glaciers of. -elevation of land in Scotland and. -Murchison sees no trace of glaciers in. -Ramsay on denudation of S. Wallace, A.R., on beauty. -criticises the expression, "Natural Selection." -Darwin on cleverness of. -letters to. -letters to Darwin from. -on Mastodon from Timor. -notes by. -on pangenesis. -review of Bastian's "Beginnings of Life." -on sterility. -on success of Natural Selection. -attributes Natural Selection to Darwin. -on colour and birds' nests. -Darwin's criticism of his "Geographical Distribution of Animals." -differs from Darwin. -on evolution of man. -"Island Life." -on wings of lepidoptera. -review of Darwin's book on Expression. -review of Lyell's "Principles of Geology." -on Round Island. -same ideas hit on by Darwin and. -supplies information to Darwin on Sexual Selection. -on variation. -at work on narrative of travels. Wallace, Dr., on sexes in Bombyx. -on caterpillars. Wallich, on Oxyspora paniculata. Wallis, H.M., on ears. -letters to. Walpole. Walsh, Benjamin Dann: was born at Frome, in England, in 1808, and died in America in 1869, from the result of a railway accident. He entered at Trinity College, Cambridge, and obtained a fellowship there after being fifth classic in 1831. He was therefore a contemporary of Darwin's at the University, though not a "schoolmate," as the "American Entomologist" puts it. He was the author of "A Historical Account of the University of Cambridge and its Colleges," London, 2nd edition, 1837; also of a translation of part of "Aristophanes," 1837: from the dedication of this book it seems that he was at St. Paul's School, London. He settled in America in 1838, but only began serious Entomology about 1858. He never returned to England. In a letter to Mr. Darwin, November 7th, 1864, he gives a curious account of the solitary laborious life he led for many years. "When I left England in 1838," he writes, "I was possessed with an absurd notion that I would live a perfectly natural life, independent of the whole world--in me ipso totus teres atque rotundus. So I bought several hundred acres of wild land in the wilderness, twenty miles from any settlement that you would call even a village, and with only a single neighbor. There I gradually opened a farm, working myself like a horse, raising great quantities of hogs and bullocks...I did all kinds of jobs for myself, from mending a pair of boots to hooping a barrel." After nearly dying of malaria, he sold his land at a great loss, and found that after twelve years' work he was just 1000 dollars poorer than when he began. He then went into the lumber business at Rock Island, Illinois. After seven years he invested most of his savings in building "ten two-storey brick houses for rent." He states that the repairs of the houses occupied about one-fourth of his time, and the remainder he was able to devote to entomology. He afterwards edited the "Practical Entomologist." In regard to this work he wrote (February 25th, 1867):--"Editing the 'Practical Entomologist' does undoubtedly take up a good deal of my time, but I also pick up a good deal of information of real scientific value from its correspondents. Besides, this great American nation has hitherto had a supreme contempt for Natural History, because they have hitherto believed that it has nothing to do with the dollars and cents. After hammering away at them for a year or two, I have at last succeeded in touching the 'pocket nerve' in Uncle Sam's body, and he is gradually being galvanised into the conviction that science has the power to make him richer." It is difficult to realise that even forty years ago the position of science in Illinois was what Mr. Walsh describes it to be: "You cannot have the remotest conception of the ideas of even our best- educated Americans as to the pursuit of science. I never yet met with a single one who could be brought to understand how or why a man should pursue science for its own pure and holy sake." Mr. L.O. Howard ("Insect Life," Volume VII., 1895, page 59) says that Harris received from the State of Massachusetts only 175 dollars for his classical report on injurious insects which appeared in 1841 and was reprinted in 1842 and 1852. It would seem that in these times Massachusetts was in much the same state of darkness as Illinois. In the winter of 1868-9 Walsh was, however, appointed State Entomologist of Illinois. He made but one report before his death. He was a man of liberal ideas, hating oppression and wrong in all its forms. On one occasion his life was threatened for an attempt to purify the town council. As an instance of "hereditary genius" it may be mentioned that his brother was a well-known writer on natural history and sporting subjects, under the pseudonym "Stonehenge." The facts here given are chiefly taken from the "American Entomologist" (St. Louis, Mo.), Volume II., page 65. -as entomologist. -letters to. -letter to Darwin from. -death of. -and C.V. Riley. Warming, E., "Lehrbuch der okologischen Pflanzengeographie." Washingtonia. Wasps, power of building cells. Water, effect on leaves (see also Rain). Water-weed, Marshall on. Waterhouse, George Robert (1810-88): held the post of Keeper of the Department of Geology in the British Museum from 1851 to 1880. -review by Darwin of his book on Mammalia. -on skeletons of rabbits. -on wide range of genera. -mentioned. Waterloo, Darwin's recollections of. Waterton. Watson, H.C., alluded to. -on the Azores. -on British agrarian plants. -on northward range of plants common to Britain and America. -objection to Darwin's views. -on Natural Selection. -mentioned. Waves, depth of action of. Wax, secretion on leaves (see also Bloom). Wealden period. Weale, J.P.M., sends locust dung from Natal to Darwin. Webb, on flora of Teneriffe. Wedgwood, Elizabeth. Wedgwood, Emma (Mrs. Darwin), letter to. Wedgwood, Hensleigh: brother-in-law to Charles Darwin. -Darwin visits. -influenced by Lyell's book on America. -on Tyndall. Wedgwood, Josiah, letter to. Weeds, adaptation to cultivated ground. -English versus American. -Asa Gray on pertinacity of. Weeping, physiology of. Weir, H.W., on Cytisus. Weir, Mr. John Jenner (1822-94): came of a family of Scotch descent; in 1839 he entered the service of the Custom House, and during the final eleven years of his service, i.e. from 1874 to 1885, held the position of Accountant and Controller-General. He was a born naturalist, and his "aptitude for exact observation was of the highest order" (Mr. M'Lachlan in the "Entomologist's Monthly Magazine," May 1894). He is chiefly known as an entomologist, but he had also extensive knowledge of Ornithology, Horticulture, and of the breeds of various domestic animals and cage-birds. His personal qualities made him many friends, and he was especially kind to beginners in the numerous subjects on which he was an authority ("Science Gossip," May 1894). -experiments on caterpillars. -letters to. -extract from letter to Darwin from. -on birds. -invited to Down. -value of his letters to Darwin. -mentioned. Weismann, A., Darwin asked to point out how far his work follows same lines as that of. -on dimorphism. -"Einfluss der Isolirung." -letters to. -Meldola's translation of "Studies in Descent." -"Studies in Theory of Descent." -faith in Sexual Selection. Wellingtonia. Wells, Dr., essay on dew. -quoted by Darwin as having enunciated principle of Natural Selection before publication of "Origin." Welwitschia, Hooker's work on. -Darwin on. -a "vegetable Ornithorhynchus." Welwitschia mirabilis, seedlings of. Wenlock, coral limestone of. West Indies, plants of. -coral reefs. -elevation and subsidence of. -orchids of. Westminster Abbey, memorial to Lyell. "Westminster Review," Huxley's review of the "Origin" in. -Wallace's article. Westwood, J.O. (1805-93): Professor of Entomology at Oxford. The Royal medal was awarded to him in 1855. He was educated at a Friends' School at Sheffield, and subsequently articled to a solicitor in London; he was for a short time a partner in the firm, but he never really practised, and devoted himself to science. He is the author of between 350 and 400 papers, chiefly on entomological and archaeological subjects, besides some twenty books. To naturalists he is known by his writings on insects, but he was also "one of the greatest living authorities on Anglo-Saxon and mediaeval manuscripts" ("Dictionary of National Biography"). -on range of genera. -and Royal medal. -mentioned. Whales, Flower on. Wheat, mummy. -fertilisation of. -forms of Russian. Whewell, W. Whiston. Whitaker, W., on escarpments. White, F.B., letter to. -on hemiptera of St. Helena. White, Gilbert, Darwin writes an account of Down in the manner of. White, on regeneration. Whiteman, R.G., letter to. Whitney, on origin of language. Wichura, Max, on hybrid willows. -on hybridisation. Widow-bird, experiments on. Wiegmann. Wiesner, Prof. J., disagrees with Darwin's views on plant movement. "Das Bewegungsvermogen der Pflanzen." -on heliotropism. -letter to. Wigand, A., "Der Darwinismus..." -Jager's work contra. Wight, Dr., on Cucurbitaceae. Wilberforce, Bishop, review in the "Quarterly." Wildness of game. Wilkes' exploring expedition, Dana's volume in reports of. Williamson, Prof. W.C. Willis, J.C., reference to his "Flowering Plants and Ferns." Willows, Walsh on galls of. -Wichura on hybrid. Wilson, A.S., letters to. -on Russian wheat. Wind-fertilised trees and plants, abundant in humid and temperate regions. Wingless birds, transport of. Wings of ostrich. Wire-bird, of St. Helena. Witches' brooms. Wives, resemblance to husbands. Wollaston, Thomas Vernon (1821-78): Wollaston was an under-graduate at Jesus College, Cambridge, and in late life published several books on the coleopterous insects of Madeira, the Canaries, the Cape Verde Islands, and other regions. He is referred to in the "Origin of Species" (Edition VI page 109) as having discovered "the remarkable fact that 200 beetles, out of the 550 species (but more are now known) inhabiting Madeira, are so far deficient in wings that they cannot fly; and that, of the twenty-nine endemic genera, no less than twenty-three have all their species in this condition!" See Obituary Notice in "Nature," Volume XVII., page 210, 1878, and "Trans. Entom. Soc." 1877, page xxxviii.) "Catalogue" (Probably the "Catalogue of the Coleopterous Insects of the Canaries in the British Museum," 1864.) -catalogue of insects of Canary Islands. -Darwin and Royal medal. -in agreement with Falconer in opposition to Darwin's views on species. -"Insecta Maderensia." -on rarity of intermediate varieties in insects. -review on the "Origin" by. -on varieties. -mentioned. Wolverhampton, abrupt termination of boulders near. Wood, fossil. Wood, T.W., drawings by. Woodcock, germination of seeds carried by. -protective colouring of. Woodd, C.H.L., letter to. Woodpecker, adaptation in. -and direct action. -form of tail of. Woodward, A.S., on Neomylodon. -and C.D. Sherborn, "Catalogue of British Fossil Vertebrata." Woodward, Samuel Pickworth (1821-65): held an appointment in the British Museum Library for a short time, and then became Sub-Curator to the Geological Society (1839). In 1845 he was appointed Professor of Geology and Natural History in the recently founded Royal Agricultural College, Cirencester; he afterwards obtained a post as first-class assistant in the Department of Geology and Mineralogy in the British Museum. Woodward's chief work, "The Manual of Mollusca," was published in 1851-56. ("A Memoir of Dr. S.P. Woodward," "Trans. Norfolk and Norwich Naturalists' Society," Volume III., page 279, 1882. By H.B. Woodward.) -letters to. World, age of the. Worms, Darwin's work on. -destruction by rain of. -intelligence of. Wrangel's "Travels in Siberia." "Wreck of the 'Favourite'," Clarke's. Wright, C., on bees' cells. -letters to. -review by. Wright, G.F., extract from letter from Asa Gray, to. Wydler, on morphology of cruciferous flower. Wyman, Jeffries (1814-74): graduated at Harvard in 1833, and afterwards entered the Medical College at Boston, receiving the M.D. degree in 1837. In 1847 Wyman was appointed Hervey Professor of Anatomy at Harvard, which position he held up to the time of his death. His contributions to zoological science numbered over a hundred papers. (See "Proc. Amer. Acad. Arts and Sciences," Volume II., 1874-75, pages 496-505.) -letter from. -on spontaneous generation. -mentioned. Xenogamy, term suggested by Kerner. Xenoneura antiquorum, Devonian insect. Xerophytic characters, not confined to dry-climate plants. Yangma Valley, Hooker's account of dam in. Yeo, Prof. Gerald. Yew, origin of Irish. York, British Association meeting (1881), (1844). -Dallas in charge of museum. Yorkshire, Hooker on glaciers in. Yucca, fertilisation by moths. Zacharias, Otto, letter to. Zante, colour of Polygala flowers in. Zea, Gartner's work on. -hermaphrodite and female flowers on a male panicle. -varieties received from Asa Gray. Zeiller, R., "Le Marquis G. de Saporta, sa Vie..." Zinziberaceae. Zittel, Karl A. von, "Handbuch der Palaeontologie." Zoea stage, in life-history of decapods. Zoological Gardens, dangerous to suggest subsidising. Zoological nomenclature. Zoologist, Darwin as. "Zoonomia," Erasmus Darwin's. Zygaena (Burnet-moth), mentioned by Darwin in his early recollections. 
2300	----	THE DESCENT OF MAN AND SELECTION IN RELATION TO SEX Works by Charles Darwin, F.R.S. Life and Letters of Charles Darwin. With an Autobiographical Chapter. Edited by Francis Darwin. Portraits. 3 volumes 36s. Popular Edition. Condensed in 1 volume 7s 6d. Naturalist's Journal of Researches into the Natural History and Geology of Countries Visited during a Voyage Round the World. With 100 Illustrations by Pritchett. 21s. Popular Edition. Woodcuts. 3s 6d. Cheaper Edition, 2s. 6d. net. Origin of Species by means of Natural Selection; or, The Preservation of Favoured Races in the Struggle for Life. Large Type Edition, 2 volumes 12s. Popular Edition, 6s. Cheaper Edition with Portrait, 2s. 6d. Various Contrivances by which Orchids are Fertilized by Insects. Woodcuts. 7s. 6d. Variation of Animals and Plants under Domestication. Illustrations. 15s. Descent of Man, and Selection in relation to Sex. Illustrations. Large Type Edition, 2 volumes 15s. Popular Edition, 7s 6d. Cheaper Edition, 2s. 6d. net. Expression of the Emotions in Man and Animals. Illustrations. 12s. Insectivorous Plants. Illustrations. 9s. Movements and Habits of Climbing Plants. Woodcuts. 6s. Cross and Self-Fertilization in the Vegetable Kingdom. Illustrations. 9s. Different Forms of Flowers on Plants of the Same Species. Illustrations. 7s. 6d. Formation of Vegetable Mould through the Action of Worms. Woodcuts. 6s. The above works are Published by John Murray. Structure and Distribution of Coral Reefs. Smith, Elder, & Co. Geological Observations on Volcanic Islands and Parts of South America. Smith, Elder, & Co. Monograph of the Cirripedia. Illustrations. 2 volumes. 8vo. Ray Society. Monograph of the Fossil Lepadidae, or Pedunculated Cirripedes of Great Britain. Palaeontographical Society. Monograph of the Fossil Balanidae and Verrucidae of Great Britain. Palaeontographical Society. THE DESCENT OF MAN AND SELECTION IN RELATION TO SEX BY CHARLES DARWIN, M.A., F.R.S. Uniform with this Volume The Origin of Species, by means of Natural Selection; or, The Preservation of Favoured Races in the Struggle for Life. Popular Edition, with a Photogravure Portrait. Large Crown 8vo. 2s. 6d. net. A Naturalist's Voyage. Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of H.M.S. "Beagle" round the World, under the Command of Capt. Fitz Roy, R.N. Popular Edition, with many Illustrations. Large Crown 8vo. 2s. 6d. net. PREFACE TO THE SECOND EDITION. During the successive reprints of the first edition of this work, published in 1871, I was able to introduce several important corrections; and now that more time has elapsed, I have endeavoured to profit by the fiery ordeal through which the book has passed, and have taken advantage of all the criticisms which seem to me sound. I am also greatly indebted to a large number of correspondents for the communication of a surprising number of new facts and remarks. These have been so numerous, that I have been able to use only the more important ones; and of these, as well as of the more important corrections, I will append a list. Some new illustrations have been introduced, and four of the old drawings have been replaced by better ones, done from life by Mr. T.W. Wood. I must especially call attention to some observations which I owe to the kindness of Prof. Huxley (given as a supplement at the end of Part I.), on the nature of the differences between the brains of man and the higher apes. I have been particularly glad to give these observations, because during the last few years several memoirs on the subject have appeared on the Continent, and their importance has been, in some cases, greatly exaggerated by popular writers. I may take this opportunity of remarking that my critics frequently assume that I attribute all changes of corporeal structure and mental power exclusively to the natural selection of such variations as are often called spontaneous; whereas, even in the first edition of the 'Origin of Species,' I distinctly stated that great weight must be attributed to the inherited effects of use and disuse, with respect both to the body and mind. I also attributed some amount of modification to the direct and prolonged action of changed conditions of life. Some allowance, too, must be made for occasional reversions of structure; nor must we forget what I have called "correlated" growth, meaning, thereby, that various parts of the organisation are in some unknown manner so connected, that when one part varies, so do others; and if variations in the one are accumulated by selection, other parts will be modified. Again, it has been said by several critics, that when I found that many details of structure in man could not be explained through natural selection, I invented sexual selection; I gave, however, a tolerably clear sketch of this principle in the first edition of the 'Origin of Species,' and I there stated that it was applicable to man. This subject of sexual selection has been treated at full length in the present work, simply because an opportunity was here first afforded me. I have been struck with the likeness of many of the half-favourable criticisms on sexual selection, with those which appeared at first on natural selection; such as, that it would explain some few details, but certainly was not applicable to the extent to which I have employed it. My conviction of the power of sexual selection remains unshaken; but it is probable, or almost certain, that several of my conclusions will hereafter be found erroneous; this can hardly fail to be the case in the first treatment of a subject. When naturalists have become familiar with the idea of sexual selection, it will, as I believe, be much more largely accepted; and it has already been fully and favourably received by several capable judges. DOWN, BECKENHAM, KENT, September, 1874. First Edition February 24, 1871. Second Edition September, 1874. CONTENTS. INTRODUCTION. PART I. THE DESCENT OR ORIGIN OF MAN. CHAPTER I. The Evidence of the Descent of Man from some Lower Form. Nature of the evidence bearing on the origin of man--Homologous structures in man and the lower animals--Miscellaneous points of correspondence--Development--Rudimentary structures, muscles, sense-organs, hair, bones, reproductive organs, etc.--The bearing of these three great classes of facts on the origin of man. CHAPTER II. On the Manner of Development of Man from some Lower Form. Variability of body and mind in man--Inheritance--Causes of variability--Laws of variation the same in man as in the lower animals--Direct action of the conditions of life--Effects of the increased use and disuse of parts--Arrested development--Reversion--Correlated variation--Rate of increase--Checks to increase--Natural selection--Man the most dominant animal in the world--Importance of his corporeal structure--The causes which have led to his becoming erect--Consequent changes of structure--Decrease in size of the canine teeth--Increased size and altered shape of the skull--Nakedness --Absence of a tail--Defenceless condition of man. CHAPTER III. Comparison of the Mental Powers of Man and the Lower Animals. The difference in mental power between the highest ape and the lowest savage, immense--Certain instincts in common--The emotions--Curiosity--Imitation--Attention--Memory--Imagination--Reason--Progressive improvement --Tools and weapons used by animals--Abstraction, Self-consciousness--Language--Sense of beauty--Belief in God, spiritual agencies, superstitions. CHAPTER IV. Comparison of the Mental Powers of Man and the Lower Animals--continued. The moral sense--Fundamental proposition--The qualities of social animals--Origin of sociability--Struggle between opposed instincts--Man a social animal--The more enduring social instincts conquer other less persistent instincts--The social virtues alone regarded by savages--The self-regarding virtues acquired at a later stage of development--The importance of the judgment of the members of the same community on conduct--Transmission of moral tendencies--Summary. CHAPTER V. On the Development of the Intellectual and Moral Faculties during Primeval and Civilised times. Advancement of the intellectual powers through natural selection--Importance of imitation--Social and moral faculties--Their development within the limits of the same tribe--Natural selection as affecting civilised nations--Evidence that civilised nations were once barbarous. CHAPTER VI. On the Affinities and Genealogy of Man. Position of man in the animal series--The natural system genealogical--Adaptive characters of slight value--Various small points of resemblance between man and the Quadrumana--Rank of man in the natural system--Birthplace and antiquity of man--Absence of fossil connecting-links--Lower stages in the genealogy of man, as inferred firstly from his affinities and secondly from his structure--Early androgynous condition of the Vertebrata --Conclusion. CHAPTER VII. On the Races of Man. The nature and value of specific characters--Application to the races of man--Arguments in favour of, and opposed to, ranking the so-called races of man as distinct species--Sub-species--Monogenists and polygenists--Convergence of character--Numerous points of resemblance in body and mind between the most distinct races of man--The state of man when he first spread over the earth--Each race not descended from a single pair--The extinction of races--The formation of races--The effects of crossing--Slight influence of the direct action of the conditions of life--Slight or no influence of natural selection--Sexual selection. PART II. SEXUAL SELECTION. CHAPTER VIII. Principles of Sexual Selection. Secondary sexual characters--Sexual selection--Manner of action--Excess of males--Polygamy--The male alone generally modified through sexual selection--Eagerness of the male--Variability of the male--Choice exerted by the female--Sexual compared with natural selection--Inheritance at corresponding periods of life, at corresponding seasons of the year, and as limited by sex--Relations between the several forms of inheritance--Causes why one sex and the young are not modified through sexual selection--Supplement on the proportional numbers of the two sexes throughout the animal kingdom--The proportion of the sexes in relation to natural selection. CHAPTER IX. Secondary Sexual Characters in the Lower Classes of the Animal Kingdom. These characters are absent in the lowest classes--Brilliant colours--Mollusca--Annelids--Crustacea, secondary sexual characters strongly developed; dimorphism; colour; characters not acquired before maturity--Spiders, sexual colours of; stridulation by the males--Myriapoda. CHAPTER X. Secondary Sexual Characters of Insects. Diversified structures possessed by the males for seizing the females--Differences between the sexes, of which the meaning is not understood--Difference in size between the sexes--Thysanura--Diptera--Hemiptera--Homoptera, musical powers possessed by the males alone--Orthoptera, musical instruments of the males, much diversified in structure; pugnacity; colours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity and odours--Coleoptera, colours; furnished with great horns, apparently as an ornament; battles; stridulating organs generally common to both sexes. CHAPTER XI. Insects, continued.--Order Lepidoptera. (Butterflies and Moths.) Courtship of Butterflies--Battles--Ticking noise--Colours common to both sexes, or more brilliant in the males--Examples--Not due to the direct action of the conditions of life--Colours adapted for protection--Colours of moths--Display--Perceptive powers of the Lepidoptera--Variability--Causes of the difference in colour between the males and females--Mimicry, female butterflies more brilliantly coloured than the males--Bright colours of caterpillars--Summary and concluding remarks on the secondary sexual character of insects--Birds and insects compared. CHAPTER XII. Secondary Sexual Characters of Fishes, Amphibians, and Reptiles. Fishes: Courtship and battles of the males--Larger size of the females--Males, bright colours and ornamental appendages; other strange characters--Colours and appendages acquired by the males during the breeding-season alone--Fishes with both sexes brilliantly coloured--Protective colours--The less conspicuous colours of the female cannot be accounted for on the principle of protection--Male fishes building nests, and taking charge of the ova and young. AMPHIBIANS: Differences in structure and colour between the sexes--Vocal organs. REPTILES: Chelonians--Crocodiles--Snakes, colours in some cases protective--Lizards, battles of--Ornamental appendages--Strange differences in structure between the sexes--Colours--Sexual differences almost as great as with birds. CHAPTER XIII. Secondary Sexual Characters of Birds. Sexual differences--Law of battle--Special weapons--Vocal organs--Instrumental music--Love-antics and dances--Decorations, permanent and seasonal--Double and single annual moults--Display of ornaments by the males. CHAPTER XIV. Birds--continued. Choice exerted by the female--Length of courtship--Unpaired birds--Mental qualities and taste for the beautiful--Preference or antipathy shewn by the female for particular males--Variability of birds--Variations sometimes abrupt--Laws of variation--Formation of ocelli--Gradations of character--Case of Peacock, Argus pheasant, and Urosticte. CHAPTER XV. Birds--continued. Discussion as to why the males alone of some species, and both sexes of others are brightly coloured--On sexually-limited inheritance, as applied to various structures and to brightly-coloured plumage--Nidification in relation to colour--Loss of nuptial plumage during the winter. CHAPTER XVI. Birds--concluded. The immature plumage in relation to the character of the plumage in both sexes when adult--Six classes of cases--Sexual differences between the males of closely-allied or representative species--The female assuming the characters of the male--Plumage of the young in relation to the summer and winter plumage of the adults--On the increase of beauty in the birds of the world--Protective colouring--Conspicuously coloured birds--Novelty appreciated--Summary of the four chapters on birds. CHAPTER XVII. Secondary Sexual Characters of Mammals. The law of battle--Special weapons, confined to the males--Cause of absence of weapons in the female--Weapons common to both sexes, yet primarily acquired by the male--Other uses of such weapons--Their high importance--Greater size of the male--Means of defence--On the preference shewn by either sex in the pairing of quadrupeds. CHAPTER XVIII. Secondary Sexual Characters of Mammals--continued. Voice--Remarkable sexual peculiarities in seals--Odour--Development of the hair--Colour of the hair and skin--Anomalous case of the female being more ornamented than the male--Colour and ornaments due to sexual selection--Colour acquired for the sake of protection--Colour, though common to both sexes, often due to sexual selection--On the disappearance of spots and stripes in adult quadrupeds--On the colours and ornaments of the Quadrumana--Summary. PART III. SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION. CHAPTER XIX. Secondary Sexual Characters of Man. Differences between man and woman--Causes of such differences, and of certain characters common to both sexes--Law of battle--Differences in mental powers, and voice--On the influence of beauty in determining the marriages of mankind--Attention paid by savages to ornaments--Their ideas of beauty in women--The tendency to exaggerate each natural peculiarity. CHAPTER XX. Secondary Sexual Characters of Man--continued. On the effects of the continued selection of women according to a different standard of beauty in each race--On the causes which interfere with sexual selection in civilised and savage nations--Conditions favourable to sexual selection during primeval times--On the manner of action of sexual selection with mankind--On the women in savage tribes having some power to choose their husbands--Absence of hair on the body, and development of the beard--Colour of the skin--Summary. CHAPTER XXI. General Summary and Conclusion. Main conclusion that man is descended from some lower form--Manner of development--Genealogy of man--Intellectual and moral faculties--Sexual selection--Concluding remarks. SUPPLEMENTAL NOTE. INDEX. THE DESCENT OF MAN; AND SELECTION IN RELATION TO SEX. ... INTRODUCTION. The nature of the following work will be best understood by a brief account of how it came to be written. During many years I collected notes on the origin or descent of man, without any intention of publishing on the subject, but rather with the determination not to publish, as I thought that I should thus only add to the prejudices against my views. It seemed to me sufficient to indicate, in the first edition of my 'Origin of Species,' that by this work "light would be thrown on the origin of man and his history;" and this implies that man must be included with other organic beings in any general conclusion respecting his manner of appearance on this earth. Now the case wears a wholly different aspect. When a naturalist like Carl Vogt ventures to say in his address as President of the National Institution of Geneva (1869), "personne, en Europe au moins, n'ose plus soutenir la creation indépendante et de toutes pièces, des espèces," it is manifest that at least a large number of naturalists must admit that species are the modified descendants of other species; and this especially holds good with the younger and rising naturalists. The greater number accept the agency of natural selection; though some urge, whether with justice the future must decide, that I have greatly overrated its importance. Of the older and honoured chiefs in natural science, many unfortunately are still opposed to evolution in every form. In consequence of the views now adopted by most naturalists, and which will ultimately, as in every other case, be followed by others who are not scientific, I have been led to put together my notes, so as to see how far the general conclusions arrived at in my former works were applicable to man. This seemed all the more desirable, as I had never deliberately applied these views to a species taken singly. When we confine our attention to any one form, we are deprived of the weighty arguments derived from the nature of the affinities which connect together whole groups of organisms--their geographical distribution in past and present times, and their geological succession. The homological structure, embryological development, and rudimentary organs of a species remain to be considered, whether it be man or any other animal, to which our attention may be directed; but these great classes of facts afford, as it appears to me, ample and conclusive evidence in favour of the principle of gradual evolution. The strong support derived from the other arguments should, however, always be kept before the mind. The sole object of this work is to consider, firstly, whether man, like every other species, is descended from some pre-existing form; secondly, the manner of his development; and thirdly, the value of the differences between the so-called races of man. As I shall confine myself to these points, it will not be necessary to describe in detail the differences between the several races--an enormous subject which has been fully described in many valuable works. The high antiquity of man has recently been demonstrated by the labours of a host of eminent men, beginning with M. Boucher de Perthes; and this is the indispensable basis for understanding his origin. I shall, therefore, take this conclusion for granted, and may refer my readers to the admirable treatises of Sir Charles Lyell, Sir John Lubbock, and others. Nor shall I have occasion to do more than to allude to the amount of difference between man and the anthropomorphous apes; for Prof. Huxley, in the opinion of most competent judges, has conclusively shewn that in every visible character man differs less from the higher apes, than these do from the lower members of the same order of Primates. This work contains hardly any original facts in regard to man; but as the conclusions at which I arrived, after drawing up a rough draft, appeared to me interesting, I thought that they might interest others. It has often and confidently been asserted, that man's origin can never be known: but ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science. The conclusion that man is the co-descendant with other species of some ancient, lower, and extinct form, is not in any degree new. Lamarck long ago came to this conclusion, which has lately been maintained by several eminent naturalists and philosophers; for instance, by Wallace, Huxley, Lyell, Vogt, Lubbock, Buchner, Rolle, etc. (1. As the works of the first-named authors are so well known, I need not give the titles; but as those of the latter are less well known in England, I will give them:--'Sechs Vorlesungen über die Darwin'sche Theorie:' zweite Auflage, 1868, von Dr L. Buchner; translated into French under the title 'Conférences sur la Théorie Darwinienne,' 1869. 'Der Mensch im Lichte der Darwin'sche Lehre,' 1865, von Dr. F. Rolle. I will not attempt to give references to all the authors who have taken the same side of the question. Thus G. Canestrini has published ('Annuario della Soc. d. Nat.,' Modena, 1867, page 81) a very curious paper on rudimentary characters, as bearing on the origin of man. Another work has (1869) been published by Dr. Francesco Barrago, bearing in Italian the title of "Man, made in the image of God, was also made in the image of the ape."), and especially by Haeckel. This last naturalist, besides his great work, 'Generelle Morphologie' (1866), has recently (1868, with a second edition in 1870), published his 'Natürliche Schöpfungsgeschichte,' in which he fully discusses the genealogy of man. If this work had appeared before my essay had been written, I should probably never have completed it. Almost all the conclusions at which I have arrived I find confirmed by this naturalist, whose knowledge on many points is much fuller than mine. Wherever I have added any fact or view from Prof. Haeckel's writings, I give his authority in the text; other statements I leave as they originally stood in my manuscript, occasionally giving in the foot-notes references to his works, as a confirmation of the more doubtful or interesting points. During many years it has seemed to me highly probable that sexual selection has played an important part in differentiating the races of man; but in my 'Origin of Species' (first edition, page 199) I contented myself by merely alluding to this belief. When I came to apply this view to man, I found it indispensable to treat the whole subject in full detail. (2. Prof. Haeckel was the only author who, at the time when this work first appeared, had discussed the subject of sexual selection, and had seen its full importance, since the publication of the 'Origin'; and this he did in a very able manner in his various works.) Consequently the second part of the present work, treating of sexual selection, has extended to an inordinate length, compared with the first part; but this could not be avoided. I had intended adding to the present volumes an essay on the expression of the various emotions by man and the lower animals. My attention was called to this subject many years ago by Sir Charles Bell's admirable work. This illustrious anatomist maintains that man is endowed with certain muscles solely for the sake of expressing his emotions. As this view is obviously opposed to the belief that man is descended from some other and lower form, it was necessary for me to consider it. I likewise wished to ascertain how far the emotions are expressed in the same manner by the different races of man. But owing to the length of the present work, I have thought it better to reserve my essay for separate publication. PART I. THE DESCENT OR ORIGIN OF MAN. CHAPTER I. THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM. Nature of the evidence bearing on the origin of man--Homologous structures in man and the lower animals--Miscellaneous points of correspondence--Development--Rudimentary structures, muscles, sense-organs, hair, bones, reproductive organs, etc.--The bearing of these three great classes of facts on the origin of man. He who wishes to decide whether man is the modified descendant of some pre-existing form, would probably first enquire whether man varies, however slightly, in bodily structure and in mental faculties; and if so, whether the variations are transmitted to his offspring in accordance with the laws which prevail with the lower animals. Again, are the variations the result, as far as our ignorance permits us to judge, of the same general causes, and are they governed by the same general laws, as in the case of other organisms; for instance, by correlation, the inherited effects of use and disuse, etc.? Is man subject to similar malconformations, the result of arrested development, of reduplication of parts, etc., and does he display in any of his anomalies reversion to some former and ancient type of structure? It might also naturally be enquired whether man, like so many other animals, has given rise to varieties and sub-races, differing but slightly from each other, or to races differing so much that they must be classed as doubtful species? How are such races distributed over the world; and how, when crossed, do they react on each other in the first and succeeding generations? And so with many other points. The enquirer would next come to the important point, whether man tends to increase at so rapid a rate, as to lead to occasional severe struggles for existence; and consequently to beneficial variations, whether in body or mind, being preserved, and injurious ones eliminated. Do the races or species of men, whichever term may be applied, encroach on and replace one another, so that some finally become extinct? We shall see that all these questions, as indeed is obvious in respect to most of them, must be answered in the affirmative, in the same manner as with the lower animals. But the several considerations just referred to may be conveniently deferred for a time: and we will first see how far the bodily structure of man shews traces, more or less plain, of his descent from some lower form. In succeeding chapters the mental powers of man, in comparison with those of the lower animals, will be considered. THE BODILY STRUCTURE OF MAN. It is notorious that man is constructed on the same general type or model as other mammals. All the bones in his skeleton can be compared with corresponding bones in a monkey, bat, or seal. So it is with his muscles, nerves, blood-vessels and internal viscera. The brain, the most important of all the organs, follows the same law, as shewn by Huxley and other anatomists. Bischoff (1. 'Grosshirnwindungen des Menschen,' 1868, s. 96. The conclusions of this author, as well as those of Gratiolet and Aeby, concerning the brain, will be discussed by Prof. Huxley in the Appendix alluded to in the Preface to this edition.), who is a hostile witness, admits that every chief fissure and fold in the brain of man has its analogy in that of the orang; but he adds that at no period of development do their brains perfectly agree; nor could perfect agreement be expected, for otherwise their mental powers would have been the same. Vulpian (2. 'Lec. sur la Phys.' 1866, page 890, as quoted by M. Dally, 'L'Ordre des Primates et le Transformisme,' 1868, page 29.), remarks: "Les différences réelles qui existent entre l'encephale de l'homme et celui des singes supérieurs, sont bien minimes. Il ne faut pas se faire d'illusions a cet égard. L'homme est bien plus près des singes anthropomorphes par les caractères anatomiques de son cerveau que ceux-ci ne le sont non seulement des autres mammifères, mais même de certains quadrumanes, des guenons et des macaques." But it would be superfluous here to give further details on the correspondence between man and the higher mammals in the structure of the brain and all other parts of the body. It may, however, be worth while to specify a few points, not directly or obviously connected with structure, by which this correspondence or relationship is well shewn. Man is liable to receive from the lower animals, and to communicate to them, certain diseases, as hydrophobia, variola, the glanders, syphilis, cholera, herpes, etc. (3. Dr. W. Lauder Lindsay has treated this subject at some length in the 'Journal of Mental Science,' July 1871; and in the 'Edinburgh Veterinary Review,' July 1858.); and this fact proves the close similarity (4. A Reviewer has criticised ('British Quarterly Review,' Oct. 1st, 1871, page 472) what I have here said with much severity and contempt; but as I do not use the term identity, I cannot see that I am greatly in error. There appears to me a strong analogy between the same infection or contagion producing the same result, or one closely similar, in two distinct animals, and the testing of two distinct fluids by the same chemical reagent.) of their tissues and blood, both in minute structure and composition, far more plainly than does their comparison under the best microscope, or by the aid of the best chemical analysis. Monkeys are liable to many of the same non-contagious diseases as we are; thus Rengger (5. 'Naturgeschichte der Säugethiere von Paraguay,' 1830, s. 50.), who carefully observed for a long time the Cebus Azarae in its native land, found it liable to catarrh, with the usual symptoms, and which, when often recurrent, led to consumption. These monkeys suffered also from apoplexy, inflammation of the bowels, and cataract in the eye. The younger ones when shedding their milk-teeth often died from fever. Medicines produced the same effect on them as on us. Many kinds of monkeys have a strong taste for tea, coffee, and spiritous liquors: they will also, as I have myself seen, smoke tobacco with pleasure. (6. The same tastes are common to some animals much lower in the scale. Mr. A. Nichols informs me that he kept in Queensland, in Australia, three individuals of the Phaseolarctus cinereus; and that, without having been taught in any way, they acquired a strong taste for rum, and for smoking tobacco.) Brehm asserts that the natives of north-eastern Africa catch the wild baboons by exposing vessels with strong beer, by which they are made drunk. He has seen some of these animals, which he kept in confinement, in this state; and he gives a laughable account of their behaviour and strange grimaces. On the following morning they were very cross and dismal; they held their aching heads with both hands, and wore a most pitiable expression: when beer or wine was offered them, they turned away with disgust, but relished the juice of lemons. (7. Brehm, 'Thierleben,' B. i. 1864, s. 75, 86. On the Ateles, s. 105. For other analogous statements, see s. 25, 107.) An American monkey, an Ateles, after getting drunk on brandy, would never touch it again, and thus was wiser than many men. These trifling facts prove how similar the nerves of taste must be in monkeys and man, and how similarly their whole nervous system is affected. Man is infested with internal parasites, sometimes causing fatal effects; and is plagued by external parasites, all of which belong to the same genera or families as those infesting other mammals, and in the case of scabies to the same species. (8. Dr. W. Lauder Lindsay, 'Edinburgh Vet. Review,' July 1858, page 13.) Man is subject, like other mammals, birds, and even insects (9. With respect to insects see Dr. Laycock, "On a General Law of Vital Periodicity," 'British Association,' 1842. Dr. Macculloch, 'Silliman's North American Journal of Science,' vol. XVII. page 305, has seen a dog suffering from tertian ague. Hereafter I shall return to this subject.), to that mysterious law, which causes certain normal processes, such as gestation, as well as the maturation and duration of various diseases, to follow lunar periods. His wounds are repaired by the same process of healing; and the stumps left after the amputation of his limbs, especially during an early embryonic period, occasionally possess some power of regeneration, as in the lowest animals. (10. I have given the evidence on this head in my 'Variation of Animals and Plants under Domestication,' vol. ii. page 15, and more could be added.) The whole process of that most important function, the reproduction of the species, is strikingly the same in all mammals, from the first act of courtship by the male (11. Mares e diversis generibus Quadrumanorum sine dubio dignoscunt feminas humanas a maribus. Primum, credo, odoratu, postea aspectu. Mr. Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus animalium erat, vir in rebus observandis cautus et sagax, hoc mihi certissime probavit, et curatores ejusdem loci et alii e ministris confirmaverunt. Sir Andrew Smith et Brehm notabant idem in Cynocephalo. Illustrissimus Cuvier etiam narrat multa de hac re, qua ut opinor, nihil turpius potest indicari inter omnia hominibus et Quadrumanis communia. Narrat enim Cynocephalum quendam in furorem incidere aspectu feminarum aliquarem, sed nequaquam accendi tanto furore ab omnibus. Semper eligebat juniores, et dignoscebat in turba, et advocabat voce gestuque.), to the birth and nurturing of the young. Monkeys are born in almost as helpless a condition as our own infants; and in certain genera the young differ fully as much in appearance from the adults, as do our children from their full-grown parents. (12. This remark is made with respect to Cynocephalus and the anthropomorphous apes by Geoffroy Saint-Hilaire and F. Cuvier, 'Histoire Nat. des Mammifères,' tom. i. 1824.) It has been urged by some writers, as an important distinction, that with man the young arrive at maturity at a much later age than with any other animal: but if we look to the races of mankind which inhabit tropical countries the difference is not great, for the orang is believed not to be adult till the age of from ten to fifteen years. (13. Huxley, 'Man's Place in Nature,' 1863, p. 34.) Man differs from woman in size, bodily strength, hairiness, etc., as well as in mind, in the same manner as do the two sexes of many mammals. So that the correspondence in general structure, in the minute structure of the tissues, in chemical composition and in constitution, between man and the higher animals, especially the anthropomorphous apes, is extremely close. EMBRYONIC DEVELOPMENT. [Fig. 1. Shows a human embryo, from Ecker, and a dog embryo, from Bischoff. Labelled in each are: a. Fore-brain, cerebral hemispheres, etc. b. Mid-brain, corpora quadrigemina. c. Hind-brain, cerebellum, medulla oblongata. d. Eye. e. Ear. f. First visceral arch. g. Second visceral arch. H. Vertebral columns and muscles in process of development. i. Anterior extremities. K. Posterior extremities. L. Tail or os coccyx.] Man is developed from an ovule, about the 125th of an inch in diameter, which differs in no respect from the ovules of other animals. The embryo itself at a very early period can hardly be distinguished from that of other members of the vertebrate kingdom. At this period the arteries run in arch-like branches, as if to carry the blood to branchiae which are not present in the higher Vertebrata, though the slits on the sides of the neck still remain (see f, g, fig. 1), marking their former position. At a somewhat later period, when the extremities are developed, "the feet of lizards and mammals," as the illustrious Von Baer remarks, "the wings and feet of birds, no less than the hands and feet of man, all arise from the same fundamental form." It is, says Prof. Huxley (14. 'Man's Place in Nature,' 1863, p. 67.), "quite in the later stages of development that the young human being presents marked differences from the young ape, while the latter departs as much from the dog in its developments, as the man does. Startling as this last assertion may appear to be, it is demonstrably true." As some of my readers may never have seen a drawing of an embryo, I have given one of man and another of a dog, at about the same early stage of development, carefully copied from two works of undoubted accuracy. (15. The human embryo (upper fig.) is from Ecker, 'Icones Phys.,' 1851-1859, tab. xxx. fig. 2. This embryo was ten lines in length, so that the drawing is much magnified. The embryo of the dog is from Bischoff, 'Entwicklungsgeschichte des Hunde-Eies,' 1845, tab. xi. fig. 42B. This drawing is five times magnified, the embryo being twenty-five days old. The internal viscera have been omitted, and the uterine appendages in both drawings removed. I was directed to these figures by Prof. Huxley, from whose work, 'Man's Place in Nature,' the idea of giving them was taken. Haeckel has also given analogous drawings in his 'Schopfungsgeschichte.') After the foregoing statements made by such high authorities, it would be superfluous on my part to give a number of borrowed details, shewing that the embryo of man closely resembles that of other mammals. It may, however, be added, that the human embryo likewise resembles certain low forms when adult in various points of structure. For instance, the heart at first exists as a simple pulsating vessel; the excreta are voided through a cloacal passage; and the os coccyx projects like a true tail, "extending considerably beyond the rudimentary legs." (16. Prof. Wyman in 'Proceedings of the American Academy of Sciences,' vol. iv. 1860, p. 17.) In the embryos of all air-breathing vertebrates, certain glands, called the corpora Wolffiana, correspond with, and act like the kidneys of mature fishes. (17. Owen, 'Anatomy of Vertebrates,' vol. i. p. 533.) Even at a later embryonic period, some striking resemblances between man and the lower animals may be observed. Bischoff says that "the convolutions of the brain in a human foetus at the end of the seventh month reach about the same stage of development as in a baboon when adult." (18. 'Die Grosshirnwindungen des Menschen,' 1868, s. 95.) The great toe, as Professor Owen remarks (19. 'Anatomy of Vertebrates,' vol. ii. p. 553.), "which forms the fulcrum when standing or walking, is perhaps the most characteristic peculiarity in the human structure;" but in an embryo, about an inch in length, Prof. Wyman (20. 'Proc. Soc. Nat. Hist.' Boston, 1863, vol. ix. p. 185.) found "that the great toe was shorter than the others; and, instead of being parallel to them, projected at an angle from the side of the foot, thus corresponding with the permanent condition of this part in the quadrumana." I will conclude with a quotation from Huxley (21. 'Man's Place in Nature,' p. 65.) who after asking, does man originate in a different way from a dog, bird, frog or fish? says, "the reply is not doubtful for a moment; without question, the mode of origin, and the early stages of the development of man, are identical with those of the animals immediately below him in the scale: without a doubt in these respects, he is far nearer to apes than the apes are to the dog." RUDIMENTS. This subject, though not intrinsically more important than the two last, will for several reasons be treated here more fully. (22. I had written a rough copy of this chapter before reading a valuable paper, "Caratteri rudimentali in ordine all' origine dell' uomo" ('Annuario della Soc. d. Naturalisti,' Modena, 1867, p. 81), by G. Canestrini, to which paper I am considerably indebted. Haeckel has given admirable discussions on this whole subject, under the title of Dysteleology, in his 'Generelle Morphologie' and 'Schöpfungsgeschichte.') Not one of the higher animals can be named which does not bear some part in a rudimentary condition; and man forms no exception to the rule. Rudimentary organs must be distinguished from those that are nascent; though in some cases the distinction is not easy. The former are either absolutely useless, such as the mammae of male quadrupeds, or the incisor teeth of ruminants which never cut through the gums; or they are of such slight service to their present possessors, that we can hardly suppose that they were developed under the conditions which now exist. Organs in this latter state are not strictly rudimentary, but they are tending in this direction. Nascent organs, on the other hand, though not fully developed, are of high service to their possessors, and are capable of further development. Rudimentary organs are eminently variable; and this is partly intelligible, as they are useless, or nearly useless, and consequently are no longer subjected to natural selection. They often become wholly suppressed. When this occurs, they are nevertheless liable to occasional reappearance through reversion--a circumstance well worthy of attention. The chief agents in causing organs to become rudimentary seem to have been disuse at that period of life when the organ is chiefly used (and this is generally during maturity), and also inheritance at a corresponding period of life. The term "disuse" does not relate merely to the lessened action of muscles, but includes a diminished flow of blood to a part or organ, from being subjected to fewer alternations of pressure, or from becoming in any way less habitually active. Rudiments, however, may occur in one sex of those parts which are normally present in the other sex; and such rudiments, as we shall hereafter see, have often originated in a way distinct from those here referred to. In some cases, organs have been reduced by means of natural selection, from having become injurious to the species under changed habits of life. The process of reduction is probably often aided through the two principles of compensation and economy of growth; but the later stages of reduction, after disuse has done all that can fairly be attributed to it, and when the saving to be effected by the economy of growth would be very small (23. Some good criticisms on this subject have been given by Messrs. Murie and Mivart, in 'Transact. Zoological Society,' 1869, vol. vii. p. 92.), are difficult to understand. The final and complete suppression of a part, already useless and much reduced in size, in which case neither compensation nor economy can come into play, is perhaps intelligible by the aid of the hypothesis of pangenesis. But as the whole subject of rudimentary organs has been discussed and illustrated in my former works (24. 'Variation of Animals and Plants under Domestication,' vol. ii pp. 317 and 397. See also 'Origin of Species,' 5th Edition p. 535.), I need here say no more on this head. Rudiments of various muscles have been observed in many parts of the human body (25. For instance, M. Richard ('Annales des Sciences Nat.,' 3rd series, Zoolog. 1852, tom. xviii. p. 13) describes and figures rudiments of what he calls the "muscle pedieux de la main," which he says is sometimes "infiniment petit." Another muscle, called "le tibial posterieur," is generally quite absent in the hand, but appears from time to time in a more or less rudimentary condition.); and not a few muscles, which are regularly present in some of the lower animals can occasionally be detected in man in a greatly reduced condition. Every one must have noticed the power which many animals, especially horses, possess of moving or twitching their skin; and this is effected by the panniculus carnosus. Remnants of this muscle in an efficient state are found in various parts of our bodies; for instance, the muscle on the forehead, by which the eyebrows are raised. The platysma myoides, which is well developed on the neck, belongs to this system. Prof. Turner, of Edinburgh, has occasionally detected, as he informs me, muscular fasciculi in five different situations, namely in the axillae, near the scapulae, etc., all of which must be referred to the system of the panniculus. He has also shewn (26. Prof. W. Turner, 'Proceedings of the Royal Society of Edinburgh,' 1866-67, p. 65.) that the musculus sternalis or sternalis brutorum, which is not an extension of the rectus abdominalis, but is closely allied to the panniculus, occurred in the proportion of about three per cent. in upwards of 600 bodies: he adds, that this muscle affords "an excellent illustration of the statement that occasional and rudimentary structures are especially liable to variation in arrangement." Some few persons have the power of contracting the superficial muscles on their scalps; and these muscles are in a variable and partially rudimentary condition. M. A. de Candolle has communicated to me a curious instance of the long-continued persistence or inheritance of this power, as well as of its unusual development. He knows a family, in which one member, the present head of the family, could, when a youth, pitch several heavy books from his head by the movement of the scalp alone; and he won wagers by performing this feat. His father, uncle, grandfather, and his three children possess the same power to the same unusual degree. This family became divided eight generations ago into two branches; so that the head of the above-mentioned branch is cousin in the seventh degree to the head of the other branch. This distant cousin resides in another part of France; and on being asked whether he possessed the same faculty, immediately exhibited his power. This case offers a good illustration how persistent may be the transmission of an absolutely useless faculty, probably derived from our remote semi-human progenitors; since many monkeys have, and frequently use the power, of largely moving their scalps up and down. (27. See my 'Expression of the Emotions in Man and Animals,' 1872, p. 144.) The extrinsic muscles which serve to move the external ear, and the intrinsic muscles which move the different parts, are in a rudimentary condition in man, and they all belong to the system of the panniculus; they are also variable in development, or at least in function. I have seen one man who could draw the whole ear forwards; other men can draw it upwards; another who could draw it backwards (28. Canestrini quotes Hyrtl. ('Annuario della Soc. dei Naturalisti,' Modena, 1867, p. 97) to the same effect.); and from what one of these persons told me, it is probable that most of us, by often touching our ears, and thus directing our attention towards them, could recover some power of movement by repeated trials. The power of erecting and directing the shell of the ears to the various points of the compass, is no doubt of the highest service to many animals, as they thus perceive the direction of danger; but I have never heard, on sufficient evidence, of a man who possessed this power, the one which might be of use to him. The whole external shell may be considered a rudiment, together with the various folds and prominences (helix and anti-helix, tragus and anti-tragus, etc.) which in the lower animals strengthen and support the ear when erect, without adding much to its weight. Some authors, however, suppose that the cartilage of the shell serves to transmit vibrations to the acoustic nerve; but Mr. Toynbee (29. 'The Diseases of the Ear,' by J. Toynbee, F.R.S., 1860, p. 12. A distinguished physiologist, Prof. Preyer, informs me that he had lately been experimenting on the function of the shell of the ear, and has come to nearly the same conclusion as that given here.), after collecting all the known evidence on this head, concludes that the external shell is of no distinct use. The ears of the chimpanzee and orang are curiously like those of man, and the proper muscles are likewise but very slightly developed. (30. Prof. A. Macalister, 'Annals and Magazine of Natural History,' vol. vii. 1871, p. 342.) I am also assured by the keepers in the Zoological Gardens that these animals never move or erect their ears; so that they are in an equally rudimentary condition with those of man, as far as function is concerned. Why these animals, as well as the progenitors of man, should have lost the power of erecting their ears, we cannot say. It may be, though I am not satisfied with this view, that owing to their arboreal habits and great strength they were but little exposed to danger, and so during a lengthened period moved their ears but little, and thus gradually lost the power of moving them. This would be a parallel case with that of those large and heavy birds, which, from inhabiting oceanic islands, have not been exposed to the attacks of beasts of prey, and have consequently lost the power of using their wings for flight. The inability to move the ears in man and several apes is, however, partly compensated by the freedom with which they can move the head in a horizontal plane, so as to catch sounds from all directions. It has been asserted that the ear of man alone possesses a lobule; but "a rudiment of it is found in the gorilla" (31. Mr. St. George Mivart, 'Elementary Anatomy,' 1873, p. 396.); and, as I hear from Prof. Preyer, it is not rarely absent in the negro. [Fig. 2. Human Ear, modelled and drawn by Mr. Woolner. The projecting point is labelled a.] The celebrated sculptor, Mr. Woolner, informs me of one little peculiarity in the external ear, which he has often observed both in men and women, and of which he perceived the full significance. His attention was first called to the subject whilst at work on his figure of Puck, to which he had given pointed ears. He was thus led to examine the ears of various monkeys, and subsequently more carefully those of man. The peculiarity consists in a little blunt point, projecting from the inwardly folded margin, or helix. When present, it is developed at birth, and, according to Prof. Ludwig Meyer, more frequently in man than in woman. Mr. Woolner made an exact model of one such case, and sent me the accompanying drawing. (Fig. 2). These points not only project inwards towards the centre of the ear, but often a little outwards from its plane, so as to be visible when the head is viewed from directly in front or behind. They are variable in size, and somewhat in position, standing either a little higher or lower; and they sometimes occur on one ear and not on the other. They are not confined to mankind, for I observed a case in one of the spider-monkeys (Ateles beelzebuth) in our Zoological Gardens; and Mr. E. Ray Lankester informs me of another case in a chimpanzee in the gardens at Hamburg. The helix obviously consists of the extreme margin of the ear folded inwards; and this folding appears to be in some manner connected with the whole external ear being permanently pressed backwards. In many monkeys, which do not stand high in the order, as baboons and some species of macacus (32. See also some remarks, and the drawings of the ears of the Lemuroidea, in Messrs. Murie and Mivart's excellent paper in 'Transactions of the Zoological Society,' vol. vii. 1869, pp. 6 and 90.), the upper portion of the ear is slightly pointed, and the margin is not at all folded inwards; but if the margin were to be thus folded, a slight point would necessarily project inwards towards the centre, and probably a little outwards from the plane of the ear; and this I believe to be their origin in many cases. On the other hand, Prof. L. Meyer, in an able paper recently published (33. '�ber das Darwin'sche Spitzohr,' Archiv fur Path. Anat. und Phys., 1871, p. 485.), maintains that the whole case is one of mere variability; and that the projections are not real ones, but are due to the internal cartilage on each side of the points not having been fully developed. I am quite ready to admit that this is the correct explanation in many instances, as in those figured by Prof. Meyer, in which there are several minute points, or the whole margin is sinuous. I have myself seen, through the kindness of Dr. L. Down, the ear of a microcephalous idiot, on which there is a projection on the outside of the helix, and not on the inward folded edge, so that this point can have no relation to a former apex of the ear. Nevertheless in some cases, my original view, that the points are vestiges of the tips of formerly erect and pointed ears, still seems to me probable. I think so from the frequency of their occurrence, and from the general correspondence in position with that of the tip of a pointed ear. In one case, of which a photograph has been sent me, the projection is so large, that supposing, in accordance with Prof. Meyer's view, the ear to be made perfect by the equal development of the cartilage throughout the whole extent of the margin, it would have covered fully one-third of the whole ear. Two cases have been communicated to me, one in North America, and the other in England, in which the upper margin is not at all folded inwards, but is pointed, so that it closely resembles the pointed ear of an ordinary quadruped in outline. In one of these cases, which was that of a young child, the father compared the ear with the drawing which I have given (34. 'The Expression of the Emotions,' p. 136.) of the ear of a monkey, the Cynopithecus niger, and says that their outlines are closely similar. If, in these two cases, the margin had been folded inwards in the normal manner, an inward projection must have been formed. I may add that in two other cases the outline still remains somewhat pointed, although the margin of the upper part of the ear is normally folded inwards--in one of them, however, very narrowly. [Fig.3. Foetus of an Orang(?). Exact copy of a photograph, shewing the form of the ear at this early age.] The following woodcut (No. 3) is an accurate copy of a photograph of the foetus of an orang (kindly sent me by Dr. Nitsche), in which it may be seen how different the pointed outline of the ear is at this period from its adult condition, when it bears a close general resemblance to that of man. It is evident that the folding over of the tip of such an ear, unless it changed greatly during its further development, would give rise to a point projecting inwards. On the whole, it still seems to me probable that the points in question are in some cases, both in man and apes, vestiges of a former condition. The nictitating membrane, or third eyelid, with its accessory muscles and other structures, is especially well developed in birds, and is of much functional importance to them, as it can be rapidly drawn across the whole eye-ball. It is found in some reptiles and amphibians, and in certain fishes, as in sharks. It is fairly well developed in the two lower divisions of the mammalian series, namely, in the monotremata and marsupials, and in some few of the higher mammals, as in the walrus. But in man, the quadrumana, and most other mammals, it exists, as is admitted by all anatomists, as a mere rudiment, called the semilunar fold. (35. Muller's 'Elements of Physiology,' Eng. translat. 1842, vol. ii. p. 1117. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 260; ibid. on the Walrus, 'Proceedings of the Zoological Society,' November 8, 1854. See also R. Knox, 'Great Artists and Anatomists,' p. 106. This rudiment apparently is somewhat larger in Negroes and Australians than in Europeans, see Carl Vogt, 'Lectures on Man,' Eng. translat. p. 129.) The sense of smell is of the highest importance to the greater number of mammals--to some, as the ruminants, in warning them of danger; to others, as the Carnivora, in finding their prey; to others, again, as the wild boar, for both purposes combined. But the sense of smell is of extremely slight service, if any, even to the dark coloured races of men, in whom it is much more highly developed than in the white and civilised races. (36. The account given by Humboldt of the power of smell possessed by the natives of South America is well known, and has been confirmed by others. M. Houzeau ('�tudes sur les Facultés Mentales,' etc., tom. i. 1872, p. 91) asserts that he repeatedly made experiments, and proved that Negroes and Indians could recognise persons in the dark by their odour. Dr. W. Ogle has made some curious observations on the connection between the power of smell and the colouring matter of the mucous membrane of the olfactory region as well as of the skin of the body. I have, therefore, spoken in the text of the dark-coloured races having a finer sense of smell than the white races. See his paper, 'Medico-Chirurgical Transactions,' London, vol. liii. 1870, p. 276.) Nevertheless it does not warn them of danger, nor guide them to their food; nor does it prevent the Esquimaux from sleeping in the most fetid atmosphere, nor many savages from eating half-putrid meat. In Europeans the power differs greatly in different individuals, as I am assured by an eminent naturalist who possesses this sense highly developed, and who has attended to the subject. Those who believe in the principle of gradual evolution, will not readily admit that the sense of smell in its present state was originally acquired by man, as he now exists. He inherits the power in an enfeebled and so far rudimentary condition, from some early progenitor, to whom it was highly serviceable, and by whom it was continually used. In those animals which have this sense highly developed, such as dogs and horses, the recollection of persons and of places is strongly associated with their odour; and we can thus perhaps understand how it is, as Dr. Maudsley has truly remarked (37. 'The Physiology and Pathology of Mind,' 2nd ed. 1868, p. 134.), that the sense of smell in man "is singularly effective in recalling vividly the ideas and images of forgotten scenes and places." Man differs conspicuously from all the other primates in being almost naked. But a few short straggling hairs are found over the greater part of the body in the man, and fine down on that of the woman. The different races differ much in hairiness; and in the individuals of the same race the hairs are highly variable, not only in abundance, but likewise in position: thus in some Europeans the shoulders are quite naked, whilst in others they bear thick tufts of hair. (38. Eschricht, �ber die Richtung der Haare am menschlichen Körper, Muller's 'Archiv fur Anat. und Phys.' 1837, s. 47. I shall often have to refer to this very curious paper.) There can be little doubt that the hairs thus scattered over the body are the rudiments of the uniform hairy coat of the lower animals. This view is rendered all the more probable, as it is known that fine, short, and pale-coloured hairs on the limbs and other parts of the body, occasionally become developed into "thickset, long, and rather coarse dark hairs," when abnormally nourished near old-standing inflamed surfaces. (39. Paget, 'Lectures on Surgical Pathology,' 1853, vol. i. p. 71.) I am informed by Sir James Paget that often several members of a family have a few hairs in their eyebrows much longer than the others; so that even this slight peculiarity seems to be inherited. These hairs, too, seem to have their representatives; for in the chimpanzee, and in certain species of Macacus, there are scattered hairs of considerable length rising from the naked skin above the eyes, and corresponding to our eyebrows; similar long hairs project from the hairy covering of the superciliary ridges in some baboons. The fine wool-like hair, or so-called lanugo, with which the human foetus during the sixth month is thickly covered, offers a more curious case. It is first developed, during the fifth month, on the eyebrows and face, and especially round the mouth, where it is much longer than that on the head. A moustache of this kind was observed by Eschricht (40. Eschricht, ibid. s. 40, 47.) on a female foetus; but this is not so surprising a circumstance as it may at first appear, for the two sexes generally resemble each other in all external characters during an early period of growth. The direction and arrangement of the hairs on all parts of the foetal body are the same as in the adult, but are subject to much variability. The whole surface, including even the forehead and ears, is thus thickly clothed; but it is a significant fact that the palms of the hands and the soles of the feet are quite naked, like the inferior surfaces of all four extremities in most of the lower animals. As this can hardly be an accidental coincidence, the woolly covering of the foetus probably represents the first permanent coat of hair in those mammals which are born hairy. Three or four cases have been recorded of persons born with their whole bodies and faces thickly covered with fine long hairs; and this strange condition is strongly inherited, and is correlated with an abnormal condition of the teeth. (41. See my 'Variation of Animals and Plants under Domestication,' vol. ii. p. 327. Prof. Alex. Brandt has recently sent me an additional case of a father and son, born in Russia, with these peculiarities. I have received drawings of both from Paris.) Prof. Alex. Brandt informs me that he has compared the hair from the face of a man thus characterised, aged thirty-five, with the lanugo of a foetus, and finds it quite similar in texture; therefore, as he remarks, the case may be attributed to an arrest of development in the hair, together with its continued growth. Many delicate children, as I have been assured by a surgeon to a hospital for children, have their backs covered by rather long silky hairs; and such cases probably come under the same head. It appears as if the posterior molar or wisdom-teeth were tending to become rudimentary in the more civilised races of man. These teeth are rather smaller than the other molars, as is likewise the case with the corresponding teeth in the chimpanzee and orang; and they have only two separate fangs. They do not cut through the gums till about the seventeenth year, and I have been assured that they are much more liable to decay, and are earlier lost than the other teeth; but this is denied by some eminent dentists. They are also much more liable to vary, both in structure and in the period of their development, than the other teeth. (42. Dr. Webb, 'Teeth in Man and the Anthropoid Apes,' as quoted by Dr. C. Carter Blake in Anthropological Review, July 1867, p. 299.) In the Melanian races, on the other hand, the wisdom-teeth are usually furnished with three separate fangs, and are generally sound; they also differ from the other molars in size, less than in the Caucasian races. (43. Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 320, 321, and 325.) Prof. Schaaffhausen accounts for this difference between the races by "the posterior dental portion of the jaw being always shortened" in those that are civilised (44. 'On the Primitive Form of the Skull,' Eng. translat., in 'Anthropological Review,' Oct. 1868, p. 426), and this shortening may, I presume, be attributed to civilised men habitually feeding on soft, cooked food, and thus using their jaws less. I am informed by Mr. Brace that it is becoming quite a common practice in the United States to remove some of the molar teeth of children, as the jaw does not grow large enough for the perfect development of the normal number. (45. Prof. Montegazza writes to me from Florence, that he has lately been studying the last molar teeth in the different races of man, and has come to the same conclusion as that given in my text, viz., that in the higher or civilised races they are on the road towards atrophy or elimination.) With respect to the alimentary canal, I have met with an account of only a single rudiment, namely the vermiform appendage of the caecum. The caecum is a branch or diverticulum of the intestine, ending in a cul-de-sac, and is extremely long in many of the lower vegetable-feeding mammals. In the marsupial koala it is actually more than thrice as long as the whole body. (46. Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441.) It is sometimes produced into a long gradually-tapering point, and is sometimes constricted in parts. It appears as if, in consequence of changed diet or habits, the caecum had become much shortened in various animals, the vermiform appendage being left as a rudiment of the shortened part. That this appendage is a rudiment, we may infer from its small size, and from the evidence which Prof. Canestrini (47. 'Annuario della Soc. d. Nat.' Modena, 1867, p. 94.) has collected of its variability in man. It is occasionally quite absent, or again is largely developed. The passage is sometimes completely closed for half or two-thirds of its length, with the terminal part consisting of a flattened solid expansion. In the orang this appendage is long and convoluted: in man it arises from the end of the short caecum, and is commonly from four to five inches in length, being only about the third of an inch in diameter. Not only is it useless, but it is sometimes the cause of death, of which fact I have lately heard two instances: this is due to small hard bodies, such as seeds, entering the passage, and causing inflammation. (48. M. C. Martins ("De l'Unité Organique," in 'Revue des Deux Mondes,' June 15, 1862, p. 16) and Haeckel ('Generelle Morphologie,' B. ii. s. 278), have both remarked on the singular fact of this rudiment sometimes causing death.) In some of the lower Quadrumana, in the Lemuridae and Carnivora, as well as in many marsupials, there is a passage near the lower end of the humerus, called the supra-condyloid foramen, through which the great nerve of the fore limb and often the great artery pass. Now in the humerus of man, there is generally a trace of this passage, which is sometimes fairly well developed, being formed by a depending hook-like process of bone, completed by a band of ligament. Dr. Struthers (49. With respect to inheritance, see Dr. Struthers in the 'Lancet,' Feb. 15, 1873, and another important paper, ibid. Jan. 24, 1863, p. 83. Dr. Knox, as I am informed, was the first anatomist who drew attention to this peculiar structure in man; see his 'Great Artists and Anatomists,' p. 63. See also an important memoir on this process by Dr. Gruber, in the 'Bulletin de l'Acad. Imp. de St. Petersbourg,' tom. xii. 1867, p. 448.), who has closely attended to the subject, has now shewn that this peculiarity is sometimes inherited, as it has occurred in a father, and in no less than four out of his seven children. When present, the great nerve invariably passes through it; and this clearly indicates that it is the homologue and rudiment of the supra-condyloid foramen of the lower animals. Prof. Turner estimates, as he informs me, that it occurs in about one per cent. of recent skeletons. But if the occasional development of this structure in man is, as seems probable, due to reversion, it is a return to a very ancient state of things, because in the higher Quadrumana it is absent. There is another foramen or perforation in the humerus, occasionally present in man, which may be called the inter-condyloid. This occurs, but not constantly, in various anthropoid and other apes (50. Mr. St. George Mivart, 'Transactions Phil. Soc.' 1867, p. 310.), and likewise in many of the lower animals. It is remarkable that this perforation seems to have been present in man much more frequently during ancient times than recently. Mr. Busk (51. "On the Caves of Gibraltar," 'Transactions of the International Congress of Prehistoric Archaeology,' Third Session, 1869, p. 159. Prof. Wyman has lately shewn (Fourth Annual Report, Peabody Museum, 1871, p. 20), that this perforation is present in thirty-one per cent. of some human remains from ancient mounds in the Western United States, and in Florida. It frequently occurs in the negro.) has collected the following evidence on this head: Prof. Broca "noticed the perforation in four and a half per cent. of the arm-bones collected in the 'Cimetière du Sud,' at Paris; and in the Grotto of Orrony, the contents of which are referred to the Bronze period, as many as eight humeri out of thirty-two were perforated; but this extraordinary proportion, he thinks, might be due to the cavern having been a sort of 'family vault.' Again, M. Dupont found thirty per cent. of perforated bones in the caves of the Valley of the Lesse, belonging to the Reindeer period; whilst M. Leguay, in a sort of dolmen at Argenteuil, observed twenty-five per cent. to be perforated; and M. Pruner-Bey found twenty-six per cent. in the same condition in bones from Vaureal. Nor should it be left unnoticed that M. Pruner-Bey states that this condition is common in Guanche skeletons." It is an interesting fact that ancient races, in this and several other cases, more frequently present structures which resemble those of the lower animals than do the modern. One chief cause seems to be that the ancient races stand somewhat nearer in the long line of descent to their remote animal-like progenitors. In man, the os coccyx, together with certain other vertebrae hereafter to be described, though functionless as a tail, plainly represent this part in other vertebrate animals. At an early embryonic period it is free, and projects beyond the lower extremities; as may be seen in the drawing (Fig. 1.) of a human embryo. Even after birth it has been known, in certain rare and anomalous cases (52. Quatrefages has lately collected the evidence on this subject. 'Revue des Cours Scientifiques,' 1867-1868, p. 625. In 1840 Fleischmann exhibited a human foetus bearing a free tail, which, as is not always the case, included vertebral bodies; and this tail was critically examined by the many anatomists present at the meeting of naturalists at Erlangen (see Marshall in Niederlandischen Archiv für Zoologie, December 1871).), to form a small external rudiment of a tail. The os coccyx is short, usually including only four vertebrae, all anchylosed together: and these are in a rudimentary condition, for they consist, with the exception of the basal one, of the centrum alone. (53. Owen, 'On the Nature of Limbs,' 1849, p. 114.) They are furnished with some small muscles; one of which, as I am informed by Prof. Turner, has been expressly described by Theile as a rudimentary repetition of the extensor of the tail, a muscle which is so largely developed in many mammals. The spinal cord in man extends only as far downwards as the last dorsal or first lumbar vertebra; but a thread-like structure (the filum terminale) runs down the axis of the sacral part of the spinal canal, and even along the back of the coccygeal bones. The upper part of this filament, as Prof. Turner informs me, is undoubtedly homologous with the spinal cord; but the lower part apparently consists merely of the pia mater, or vascular investing membrane. Even in this case the os coccyx may be said to possess a vestige of so important a structure as the spinal cord, though no longer enclosed within a bony canal. The following fact, for which I am also indebted to Prof. Turner, shews how closely the os coccyx corresponds with the true tail in the lower animals: Luschka has recently discovered at the extremity of the coccygeal bones a very peculiar convoluted body, which is continuous with the middle sacral artery; and this discovery led Krause and Meyer to examine the tail of a monkey (Macacus), and of a cat, in both of which they found a similarly convoluted body, though not at the extremity. The reproductive system offers various rudimentary structures; but these differ in one important respect from the foregoing cases. Here we are not concerned with the vestige of a part which does not belong to the species in an efficient state, but with a part efficient in the one sex, and represented in the other by a mere rudiment. Nevertheless, the occurrence of such rudiments is as difficult to explain, on the belief of the separate creation of each species, as in the foregoing cases. Hereafter I shall have to recur to these rudiments, and shall shew that their presence generally depends merely on inheritance, that is, on parts acquired by one sex having been partially transmitted to the other. I will in this place only give some instances of such rudiments. It is well known that in the males of all mammals, including man, rudimentary mammae exist. These in several instances have become well developed, and have yielded a copious supply of milk. Their essential identity in the two sexes is likewise shewn by their occasional sympathetic enlargement in both during an attack of the measles. The vesicula prostatica, which has been observed in many male mammals, is now universally acknowledged to be the homologue of the female uterus, together with the connected passage. It is impossible to read Leuckart's able description of this organ, and his reasoning, without admitting the justness of his conclusion. This is especially clear in the case of those mammals in which the true female uterus bifurcates, for in the males of these the vesicula likewise bifurcates. (54. Leuckart, in Todd's 'Cyclopaedia of Anatomy' 1849-52, vol. iv. p. 1415. In man this organ is only from three to six lines in length, but, like so many other rudimentary parts, it is variable in development as well as in other characters.) Some other rudimentary structures belonging to the reproductive system might have been here adduced. (55. See, on this subject, Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 675, 676, 706.) The bearing of the three great classes of facts now given is unmistakeable. But it would be superfluous fully to recapitulate the line of argument given in detail in my 'Origin of Species.' The homological construction of the whole frame in the members of the same class is intelligible, if we admit their descent from a common progenitor, together with their subsequent adaptation to diversified conditions. On any other view, the similarity of pattern between the hand of a man or monkey, the foot of a horse, the flipper of a seal, the wing of a bat, etc., is utterly inexplicable. (56. Prof. Bianconi, in a recently published work, illustrated by admirable engravings ('La Théorie Darwinienne et la création dite indépendante,' 1874), endeavours to shew that homological structures, in the above and other cases, can be fully explained on mechanical principles, in accordance with their uses. No one has shewn so well, how admirably such structures are adapted for their final purpose; and this adaptation can, as I believe, be explained through natural selection. In considering the wing of a bat, he brings forward (p. 218) what appears to me (to use Auguste Comte's words) a mere metaphysical principle, namely, the preservation "in its integrity of the mammalian nature of the animal." In only a few cases does he discuss rudiments, and then only those parts which are partially rudimentary, such as the little hoofs of the pig and ox, which do not touch the ground; these he shews clearly to be of service to the animal. It is unfortunate that he did not consider such cases as the minute teeth, which never cut through the jaw in the ox, or the mammae of male quadrupeds, or the wings of certain beetles, existing under the soldered wing-covers, or the vestiges of the pistil and stamens in various flowers, and many other such cases. Although I greatly admire Prof. Bianconi's work, yet the belief now held by most naturalists seems to me left unshaken, that homological structures are inexplicable on the principle of mere adaptation.) It is no scientific explanation to assert that they have all been formed on the same ideal plan. With respect to development, we can clearly understand, on the principle of variations supervening at a rather late embryonic period, and being inherited at a corresponding period, how it is that the embryos of wonderfully different forms should still retain, more or less perfectly, the structure of their common progenitor. No other explanation has ever been given of the marvellous fact that the embryos of a man, dog, seal, bat, reptile, etc., can at first hardly be distinguished from each other. In order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under changed habits of life they became greatly reduced, either from simple disuse, or through the natural selection of those individuals which were least encumbered with a superfluous part, aided by the other means previously indicated. Thus we can understand how it has come to pass that man and all other vertebrate animals have been constructed on the same general model, why they pass through the same early stages of development, and why they retain certain rudiments in common. Consequently we ought frankly to admit their community of descent: to take any other view, is to admit that our own structure, and that of all the animals around us, is a mere snare laid to entrap our judgment. This conclusion is greatly strengthened, if we look to the members of the whole animal series, and consider the evidence derived from their affinities or classification, their geographical distribution and geological succession. It is only our natural prejudice, and that arrogance which made our forefathers declare that they were descended from demi-gods, which leads us to demur to this conclusion. But the time will before long come, when it will be thought wonderful that naturalists, who were well acquainted with the comparative structure and development of man, and other mammals, should have believed that each was the work of a separate act of creation. CHAPTER II. ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM. Variability of body and mind in man--Inheritance--Causes of variability--Laws of variation the same in man as in the lower animals--Direct action of the conditions of life--Effects of the increased use and disuse of parts--Arrested development--Reversion--Correlated variation--Rate of increase--Checks to increase--Natural selection--Man the most dominant animal in the world--Importance of his corporeal structure--The causes which have led to his becoming erect--Consequent changes of structure--Decrease in size of the canine teeth--Increased size and altered shape of the skull--Nakedness --Absence of a tail--Defenceless condition of man. It is manifest that man is now subject to much variability. No two individuals of the same race are quite alike. We may compare millions of faces, and each will be distinct. There is an equally great amount of diversity in the proportions and dimensions of the various parts of the body; the length of the legs being one of the most variable points. (1. 'Investigations in Military and Anthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p. 256.) Although in some quarters of the world an elongated skull, and in other quarters a short skull prevails, yet there is great diversity of shape even within the limits of the same race, as with the aborigines of America and South Australia--the latter a race "probably as pure and homogeneous in blood, customs, and language as any in existence"--and even with the inhabitants of so confined an area as the Sandwich Islands. (2. With respect to the "Cranial forms of the American aborigines," see Dr. Aitken Meigs in 'Proc. Acad. Nat. Sci.' Philadelphia, May 1868. On the Australians, see Huxley, in Lyell's 'Antiquity of Man,' 1863, p. 87. On the Sandwich Islanders, Prof. J. Wyman, 'Observations on Crania,' Boston, 1868, p. 18.) An eminent dentist assures me that there is nearly as much diversity in the teeth as in the features. The chief arteries so frequently run in abnormal courses, that it has been found useful for surgical purposes to calculate from 1040 corpses how often each course prevails. (3. 'Anatomy of the Arteries,' by R. Quain. Preface, vol. i. 1844.) The muscles are eminently variable: thus those of the foot were found by Prof. Turner (4. 'Transactions of the Royal Society of Edinburgh,' vol. xxiv. pp. 175, 189.) not to be strictly alike in any two out of fifty bodies; and in some the deviations were considerable. He adds, that the power of performing the appropriate movements must have been modified in accordance with the several deviations. Mr. J. Wood has recorded (5. 'Proceedings Royal Society,' 1867, p. 544; also 1868, pp. 483, 524. There is a previous paper, 1866, p. 229.) the occurrence of 295 muscular variations in thirty-six subjects, and in another set of the same number no less than 558 variations, those occurring on both sides of the body being only reckoned as one. In the last set, not one body out of the thirty-six was "found totally wanting in departures from the standard descriptions of the muscular system given in anatomical text books." A single body presented the extraordinary number of twenty-five distinct abnormalities. The same muscle sometimes varies in many ways: thus Prof. Macalister describes (6. 'Proc. R. Irish Academy,' vol. x. 1868, p. 141.) no less than twenty distinct variations in the palmaris accessorius. The famous old anatomist, Wolff (7. 'Act. Acad. St. Petersburg,' 1778, part ii. p. 217.), insists that the internal viscera are more variable than the external parts: Nulla particula est quae non aliter et aliter in aliis se habeat hominibus. He has even written a treatise on the choice of typical examples of the viscera for representation. A discussion on the beau-ideal of the liver, lungs, kidneys, etc., as of the human face divine, sounds strange in our ears. The variability or diversity of the mental faculties in men of the same race, not to mention the greater differences between the men of distinct races, is so notorious that not a word need here be said. So it is with the lower animals. All who have had charge of menageries admit this fact, and we see it plainly in our dogs and other domestic animals. Brehm especially insists that each individual monkey of those which he kept tame in Africa had its own peculiar disposition and temper: he mentions one baboon remarkable for its high intelligence; and the keepers in the Zoological Gardens pointed out to me a monkey, belonging to the New World division, equally remarkable for intelligence. Rengger, also, insists on the diversity in the various mental characters of the monkeys of the same species which he kept in Paraguay; and this diversity, as he adds, is partly innate, and partly the result of the manner in which they have been treated or educated. (8. Brehm, 'Thierleben,' B. i. ss. 58, 87. Rengger, 'Säugethiere von Paraguay,' s. 57.) I have elsewhere (9. 'Variation of Animals and Plants under Domestication,' vol. ii. chap. xii.) so fully discussed the subject of Inheritance, that I need here add hardly anything. A greater number of facts have been collected with respect to the transmission of the most trifling, as well as of the most important characters in man, than in any of the lower animals; though the facts are copious enough with respect to the latter. So in regard to mental qualities, their transmission is manifest in our dogs, horses, and other domestic animals. Besides special tastes and habits, general intelligence, courage, bad and good temper, etc., are certainly transmitted. With man we see similar facts in almost every family; and we now know, through the admirable labours of Mr. Galton (10. 'Hereditary Genius: an Inquiry into its Laws and Consequences,' 1869.), that genius which implies a wonderfully complex combination of high faculties, tends to be inherited; and, on the other hand, it is too certain that insanity and deteriorated mental powers likewise run in families. With respect to the causes of variability, we are in all cases very ignorant; but we can see that in man as in the lower animals, they stand in some relation to the conditions to which each species has been exposed, during several generations. Domesticated animals vary more than those in a state of nature; and this is apparently due to the diversified and changing nature of the conditions to which they have been subjected. In this respect the different races of man resemble domesticated animals, and so do the individuals of the same race, when inhabiting a very wide area, like that of America. We see the influence of diversified conditions in the more civilised nations; for the members belonging to different grades of rank, and following different occupations, present a greater range of character than do the members of barbarous nations. But the uniformity of savages has often been exaggerated, and in some cases can hardly be said to exist. (11. Mr. Bates remarks ('The Naturalist on the Amazons,' 1863, vol. ii p. 159), with respect to the Indians of the same South American tribe, "no two of them were at all similar in the shape of the head; one man had an oval visage with fine features, and another was quite Mongolian in breadth and prominence of cheek, spread of nostrils, and obliquity of eyes.") It is, nevertheless, an error to speak of man, even if we look only to the conditions to which he has been exposed, as "far more domesticated" (12. Blumenbach, 'Treatises on Anthropology.' Eng. translat., 1865, p. 205.) than any other animal. Some savage races, such as the Australians, are not exposed to more diversified conditions than are many species which have a wide range. In another and much more important respect, man differs widely from any strictly domesticated animal; for his breeding has never long been controlled, either by methodical or unconscious selection. No race or body of men has been so completely subjugated by other men, as that certain individuals should be preserved, and thus unconsciously selected, from somehow excelling in utility to their masters. Nor have certain male and female individuals been intentionally picked out and matched, except in the well-known case of the Prussian grenadiers; and in this case man obeyed, as might have been expected, the law of methodical selection; for it is asserted that many tall men were reared in the villages inhabited by the grenadiers and their tall wives. In Sparta, also, a form of selection was followed, for it was enacted that all children should be examined shortly after birth; the well-formed and vigorous being preserved, the others left to perish. (13. Mitford's 'History of Greece,' vol. i. p. 282. It appears also from a passage in Xenophon's 'Memorabilia,' B. ii. 4 (to which my attention has been called by the Rev. J.N. Hoare), that it was a well recognised principle with the Greeks, that men ought to select their wives with a view to the health and vigour of their children. The Grecian poet, Theognis, who lived 550 B.C., clearly saw how important selection, if carefully applied, would be for the improvement of mankind. He saw, likewise, that wealth often checks the proper action of sexual selection. He thus writes: "With kine and horses, Kurnus! we proceed By reasonable rules, and choose a breed For profit and increase, at any price: Of a sound stock, without defect or vice. But, in the daily matches that we make, The price is everything: for money's sake, Men marry: women are in marriage given The churl or ruffian, that in wealth has thriven, May match his offspring with the proudest race: Thus everything is mix'd, noble and base! If then in outward manner, form, and mind, You find us a degraded, motley kind, Wonder no more, my friend! the cause is plain, And to lament the consequence is vain." (The Works of J. Hookham Frere, vol. ii. 1872, p. 334.)) If we consider all the races of man as forming a single species, his range is enormous; but some separate races, as the Americans and Polynesians, have very wide ranges. It is a well-known law that widely-ranging species are much more variable than species with restricted ranges; and the variability of man may with more truth be compared with that of widely-ranging species, than with that of domesticated animals. Not only does variability appear to be induced in man and the lower animals by the same general causes, but in both the same parts of the body are affected in a closely analogous manner. This has been proved in such full detail by Godron and Quatrefages, that I need here only refer to their works. (14. Godron, 'De l'Espèce,' 1859, tom. ii. livre 3. Quatrefages, 'Unité de l'Espèce Humaine,' 1861. Also Lectures on Anthropology, given in the 'Revue des Cours Scientifiques,' 1866-1868.) Monstrosities, which graduate into slight variations, are likewise so similar in man and the lower animals, that the same classification and the same terms can be used for both, as has been shewn by Isidore Geoffroy St.-Hilaire. (15. 'Hist. Gen. et Part. des Anomalies de l'Organisation,' in three volumes, tom. i. 1832.) In my work on the variation of domestic animals, I have attempted to arrange in a rude fashion the laws of variation under the following heads:--The direct and definite action of changed conditions, as exhibited by all or nearly all the individuals of the same species, varying in the same manner under the same circumstances. The effects of the long-continued use or disuse of parts. The cohesion of homologous parts. The variability of multiple parts. Compensation of growth; but of this law I have found no good instance in the case of man. The effects of the mechanical pressure of one part on another; as of the pelvis on the cranium of the infant in the womb. Arrests of development, leading to the diminution or suppression of parts. The reappearance of long-lost characters through reversion. And lastly, correlated variation. All these so-called laws apply equally to man and the lower animals; and most of them even to plants. It would be superfluous here to discuss all of them (16. I have fully discussed these laws in my 'Variation of Animals and Plants under Domestication,' vol. ii. chap. xxii. and xxiii. M. J.P. Durand has lately (1868) published a valuable essay, 'De l'Influence des Milieux,' etc. He lays much stress, in the case of plants, on the nature of the soil.); but several are so important, that they must be treated at considerable length. THE DIRECT AND DEFINITE ACTION OF CHANGED CONDITIONS. This is a most perplexing subject. It cannot be denied that changed conditions produce some, and occasionally a considerable effect, on organisms of all kinds; and it seems at first probable that if sufficient time were allowed this would be the invariable result. But I have failed to obtain clear evidence in favour of this conclusion; and valid reasons may be urged on the other side, at least as far as the innumerable structures are concerned, which are adapted for special ends. There can, however, be no doubt that changed conditions induce an almost indefinite amount of fluctuating variability, by which the whole organisation is rendered in some degree plastic. In the United States, above 1,000,000 soldiers, who served in the late war, were measured, and the States in which they were born and reared were recorded. (17. 'Investigations in Military and Anthrop. Statistics,' etc., 1869, by B.A. Gould, pp. 93, 107, 126, 131, 134.) From this astonishing number of observations it is proved that local influences of some kind act directly on stature; and we further learn that "the State where the physical growth has in great measure taken place, and the State of birth, which indicates the ancestry, seem to exert a marked influence on the stature." For instance, it is established, "that residence in the Western States, during the years of growth, tends to produce increase of stature." On the other hand, it is certain that with sailors, their life delays growth, as shewn "by the great difference between the statures of soldiers and sailors at the ages of seventeen and eighteen years." Mr. B.A. Gould endeavoured to ascertain the nature of the influences which thus act on stature; but he arrived only at negative results, namely that they did not relate to climate, the elevation of the land, soil, nor even "in any controlling degree" to the abundance or the need of the comforts of life. This latter conclusion is directly opposed to that arrived at by Villerme, from the statistics of the height of the conscripts in different parts of France. When we compare the differences in stature between the Polynesian chiefs and the lower orders within the same islands, or between the inhabitants of the fertile volcanic and low barren coral islands of the same ocean (18. For the Polynesians, see Prichard's 'Physical History of Mankind,' vol. v. 1847, pp. 145, 283. Also Godron, 'De l'Espèce,' tom. ii. p. 289. There is also a remarkable difference in appearance between the closely-allied Hindoos inhabiting the Upper Ganges and Bengal; see Elphinstone's 'History of India,' vol. i. p. 324.) or again between the Fuegians on the eastern and western shores of their country, where the means of subsistence are very different, it is scarcely possible to avoid the conclusion that better food and greater comfort do influence stature. But the preceding statements shew how difficult it is to arrive at any precise result. Dr. Beddoe has lately proved that, with the inhabitants of Britain, residence in towns and certain occupations have a deteriorating influence on height; and he infers that the result is to a certain extent inherited, as is likewise the case in the United States. Dr. Beddoe further believes that wherever a "race attains its maximum of physical development, it rises highest in energy and moral vigour." (19. 'Memoirs, Anthropological Society,' vol. iii. 1867-69, pp. 561, 565, 567.) Whether external conditions produce any other direct effect on man is not known. It might have been expected that differences of climate would have had a marked influence, inasmuch as the lungs and kidneys are brought into activity under a low temperature, and the liver and skin under a high one. (20. Dr. Brakenridge, 'Theory of Diathesis,' 'Medical Times,' June 19 and July 17, 1869.) It was formerly thought that the colour of the skin and the character of the hair were determined by light or heat; and although it can hardly be denied that some effect is thus produced, almost all observers now agree that the effect has been very small, even after exposure during many ages. But this subject will be more properly discussed when we treat of the different races of mankind. With our domestic animals there are grounds for believing that cold and damp directly affect the growth of the hair; but I have not met with any evidence on this head in the case of man. EFFECTS OF THE INCREASED USE AND DISUSE OF PARTS. It is well known that use strengthens the muscles in the individual, and complete disuse, or the destruction of the proper nerve, weakens them. When the eye is destroyed, the optic nerve often becomes atrophied. When an artery is tied, the lateral channels increase not only in diameter, but in the thickness and strength of their coats. When one kidney ceases to act from disease, the other increases in size, and does double work. Bones increase not only in thickness, but in length, from carrying a greater weight. (21. I have given authorities for these several statements in my 'Variation of Animals and Plants under Domestication,' vol. ii. pp. 297-300. Dr. Jaeger, "�ber das Langenwachsthum der Knochen," 'Jenäischen Zeitschrift,' B. v. Heft. i.) Different occupations, habitually followed, lead to changed proportions in various parts of the body. Thus it was ascertained by the United States Commission (22. 'Investigations,' etc., by B.A. Gould, 1869, p. 288.) that the legs of the sailors employed in the late war were longer by 0.217 of an inch than those of the soldiers, though the sailors were on an average shorter men; whilst their arms were shorter by 1.09 of an inch, and therefore, out of proportion, shorter in relation to their lesser height. This shortness of the arms is apparently due to their greater use, and is an unexpected result: but sailors chiefly use their arms in pulling, and not in supporting weights. With sailors, the girth of the neck and the depth of the instep are greater, whilst the circumference of the chest, waist, and hips is less, than in soldiers. Whether the several foregoing modifications would become hereditary, if the same habits of life were followed during many generations, is not known, but it is probable. Rengger (23. 'Säugethiere von Paraguay,' 1830, s. 4.) attributes the thin legs and thick arms of the Payaguas Indians to successive generations having passed nearly their whole lives in canoes, with their lower extremities motionless. Other writers have come to a similar conclusion in analogous cases. According to Cranz (24. 'History of Greenland,' Eng. translat., 1767, vol. i. p. 230.), who lived for a long time with the Esquimaux, "the natives believe that ingenuity and dexterity in seal-catching (their highest art and virtue) is hereditary; there is really something in it, for the son of a celebrated seal-catcher will distinguish himself, though he lost his father in childhood." But in this case it is mental aptitude, quite as much as bodily structure, which appears to be inherited. It is asserted that the hands of English labourers are at birth larger than those of the gentry. (25. 'Intermarriage,' by Alex. Walker, 1838, p. 377.) From the correlation which exists, at least in some cases (26. 'The Variation of Animals under Domestication,' vol. i. p. 173.), between the development of the extremities and of the jaws, it is possible that in those classes which do not labour much with their hands and feet, the jaws would be reduced in size from this cause. That they are generally smaller in refined and civilised men than in hard-working men or savages, is certain. But with savages, as Mr. Herbert Spencer (27. 'Principles of Biology,' vol. i. p. 455.) has remarked, the greater use of the jaws in chewing coarse, uncooked food, would act in a direct manner on the masticatory muscles, and on the bones to which they are attached. In infants, long before birth, the skin on the soles of the feet is thicker than on any other part of the body; (28. Paget, 'Lectures on Surgical Pathology,' vol. ii, 1853, p. 209.) and it can hardly be doubted that this is due to the inherited effects of pressure during a long series of generations. It is familiar to every one that watchmakers and engravers are liable to be short-sighted, whilst men living much out of doors, and especially savages, are generally long-sighted. (29. It is a singular and unexpected fact that sailors are inferior to landsmen in their mean distance of distinct vision. Dr. B.A. Gould ('Sanitary Memoirs of the War of the Rebellion,' 1869, p. 530), has proved this to be the case; and he accounts for it by the ordinary range of vision in sailors being "restricted to the length of the vessel and the height of the masts.") Short-sight and long-sight certainly tend to be inherited. (30. 'The Variation of Animals under Domestication,' vol. i. p. 8.) The inferiority of Europeans, in comparison with savages, in eyesight and in the other senses, is no doubt the accumulated and transmitted effect of lessened use during many generations; for Rengger (31. 'Säugethiere von Paraguay,' s. 8, 10. I have had good opportunities for observing the extraordinary power of eyesight in the Fuegians. See also Lawrence ('Lectures on Physiology,' etc., 1822, p. 404) on this same subject. M. Giraud-Teulon has recently collected ('Revue des Cours Scientifiques,' 1870, p. 625) a large and valuable body of evidence proving that the cause of short-sight, "C'est le travail assidu, de près.") states that he has repeatedly observed Europeans, who had been brought up and spent their whole lives with the wild Indians, who nevertheless did not equal them in the sharpness of their senses. The same naturalist observes that the cavities in the skull for the reception of the several sense-organs are larger in the American aborigines than in Europeans; and this probably indicates a corresponding difference in the dimensions of the organs themselves. Blumenbach has also remarked on the large size of the nasal cavities in the skulls of the American aborigines, and connects this fact with their remarkably acute power of smell. The Mongolians of the plains of northern Asia, according to Pallas, have wonderfully perfect senses; and Prichard believes that the great breadth of their skulls across the zygomas follows from their highly-developed sense organs. (32. Prichard, 'Physical History of Mankind,' on the authority of Blumenbach, vol. i. 1851, p. 311; for the statement by Pallas, vol. iv. 1844, p. 407.) The Quechua Indians inhabit the lofty plateaux of Peru; and Alcide d'Orbigny states (33. Quoted by Prichard, 'Researches into the Physical History of Mankind,' vol. v. p. 463.) that, from continually breathing a highly rarefied atmosphere, they have acquired chests and lungs of extraordinary dimensions. The cells, also, of the lungs are larger and more numerous than in Europeans. These observations have been doubted, but Mr. D. Forbes carefully measured many Aymaras, an allied race, living at the height of between 10,000 and 15,000 feet; and he informs me (34. Mr. Forbes' valuable paper is now published in the 'Journal of the Ethnological Society of London,' new series, vol. ii. 1870, p.193.) that they differ conspicuously from the men of all other races seen by him in the circumference and length of their bodies. In his table of measurements, the stature of each man is taken at 1000, and the other measurements are reduced to this standard. It is here seen that the extended arms of the Aymaras are shorter than those of Europeans, and much shorter than those of Negroes. The legs are likewise shorter; and they present this remarkable peculiarity, that in every Aymara measured, the femur is actually shorter than the tibia. On an average, the length of the femur to that of the tibia is as 211 to 252; whilst in two Europeans, measured at the same time, the femora to the tibiae were as 244 to 230; and in three Negroes as 258 to 241. The humerus is likewise shorter relatively to the forearm. This shortening of that part of the limb which is nearest to the body, appears to be, as suggested to me by Mr. Forbes, a case of compensation in relation with the greatly increased length of the trunk. The Aymaras present some other singular points of structure, for instance, the very small projection of the heel. These men are so thoroughly acclimatised to their cold and lofty abode, that when formerly carried down by the Spaniards to the low eastern plains, and when now tempted down by high wages to the gold-washings, they suffer a frightful rate of mortality. Nevertheless Mr. Forbes found a few pure families which had survived during two generations: and he observed that they still inherited their characteristic peculiarities. But it was manifest, even without measurement, that these peculiarities had all decreased; and on measurement, their bodies were found not to be so much elongated as those of the men on the high plateau; whilst their femora had become somewhat lengthened, as had their tibiae, although in a less degree. The actual measurements may be seen by consulting Mr. Forbes's memoir. From these observations, there can, I think, be no doubt that residence during many generations at a great elevation tends, both directly and indirectly, to induce inherited modifications in the proportions of the body. (35. Dr. Wilckens ('Landwirthschaft. Wochenblatt,' No. 10, 1869) has lately published an interesting essay shewing how domestic animals, which live in mountainous regions, have their frames modified.) Although man may not have been much modified during the latter stages of his existence through the increased or decreased use of parts, the facts now given shew that his liability in this respect has not been lost; and we positively know that the same law holds good with the lower animals. Consequently we may infer that when at a remote epoch the progenitors of man were in a transitional state, and were changing from quadrupeds into bipeds, natural selection would probably have been greatly aided by the inherited effects of the increased or diminished use of the different parts of the body. ARRESTS OF DEVELOPMENT. There is a difference between arrested development and arrested growth, for parts in the former state continue to grow whilst still retaining their early condition. Various monstrosities come under this head; and some, as a cleft palate, are known to be occasionally inherited. It will suffice for our purpose to refer to the arrested brain-development of microcephalous idiots, as described in Vogt's memoir. (36. 'Mémoire sur les Microcephales,' 1867, pp. 50, 125, 169, 171, 184-198.) Their skulls are smaller, and the convolutions of the brain are less complex than in normal men. The frontal sinus, or the projection over the eye-brows, is largely developed, and the jaws are prognathous to an "effrayant" degree; so that these idiots somewhat resemble the lower types of mankind. Their intelligence, and most of their mental faculties, are extremely feeble. They cannot acquire the power of speech, and are wholly incapable of prolonged attention, but are much given to imitation. They are strong and remarkably active, continually gambolling and jumping about, and making grimaces. They often ascend stairs on all-fours; and are curiously fond of climbing up furniture or trees. We are thus reminded of the delight shewn by almost all boys in climbing trees; and this again reminds us how lambs and kids, originally alpine animals, delight to frisk on any hillock, however small. Idiots also resemble the lower animals in some other respects; thus several cases are recorded of their carefully smelling every mouthful of food before eating it. One idiot is described as often using his mouth in aid of his hands, whilst hunting for lice. They are often filthy in their habits, and have no sense of decency; and several cases have been published of their bodies being remarkably hairy. (37. Prof. Laycock sums up the character of brute-like idiots by calling them "theroid;" 'Journal of Mental Science,' July 1863. Dr. Scott ('The Deaf and Dumb,' 2nd ed. 1870, p. 10) has often observed the imbecile smelling their food. See, on this same subject, and on the hairiness of idiots, Dr. Maudsley, 'Body and Mind,' 1870, pp. 46-51. Pinel has also given a striking case of hairiness in an idiot.) REVERSION. Many of the cases to be here given, might have been introduced under the last heading. When a structure is arrested in its development, but still continues growing, until it closely resembles a corresponding structure in some lower and adult member of the same group, it may in one sense be considered as a case of reversion. The lower members in a group give us some idea how the common progenitor was probably constructed; and it is hardly credible that a complex part, arrested at an early phase of embryonic development, should go on growing so as ultimately to perform its proper function, unless it had acquired such power during some earlier state of existence, when the present exceptional or arrested structure was normal. The simple brain of a microcephalous idiot, in as far as it resembles that of an ape, may in this sense be said to offer a case of reversion. (38. In my 'Variation of Animals under Domestication' (vol. ii. p. 57), I attributed the not very rare cases of supernumerary mammae in women to reversion. I was led to this as a probable conclusion, by the additional mammae being generally placed symmetrically on the breast; and more especially from one case, in which a single efficient mamma occurred in the inguinal region of a woman, the daughter of another woman with supernumerary mammae. But I now find (see, for instance, Prof. Preyer, 'Der Kampf um das Dasein,' 1869, s. 45) that mammae erraticae, occur in other situations, as on the back, in the armpit, and on the thigh; the mammae in this latter instance having given so much milk that the child was thus nourished. The probability that the additional mammae are due to reversion is thus much weakened; nevertheless, it still seems to me probable, because two pairs are often found symmetrically on the breast; and of this I myself have received information in several cases. It is well known that some Lemurs normally have two pairs of mammae on the breast. Five cases have been recorded of the presence of more than a pair of mammae (of course rudimentary) in the male sex of mankind; see 'Journal of Anat. and Physiology,' 1872, p. 56, for a case given by Dr. Handyside, in which two brothers exhibited this peculiarity; see also a paper by Dr. Bartels, in 'Reichert's and du Bois-Reymond's Archiv.,' 1872, p. 304. In one of the cases alluded to by Dr. Bartels, a man bore five mammae, one being medial and placed above the navel; Meckel von Hemsbach thinks that this latter case is illustrated by a medial mamma occurring in certain Cheiroptera. On the whole, we may well doubt if additional mammae would ever have been developed in both sexes of mankind, had not his early progenitors been provided with more than a single pair. In the above work (vol. ii. p. 12), I also attributed, though with much hesitation, the frequent cases of polydactylism in men and various animals to reversion. I was partly led to this through Prof. Owen's statement, that some of the Ichthyopterygia possess more than five digits, and therefore, as I supposed, had retained a primordial condition; but Prof. Gegenbaur ('Jenaischen Zeitschrift,' B. v. Heft 3, s. 341), disputes Owen's conclusion. On the other hand, according to the opinion lately advanced by Dr. Gunther, on the paddle of Ceratodus, which is provided with articulated bony rays on both sides of a central chain of bones, there seems no great difficulty in admitting that six or more digits on one side, or on both sides, might reappear through reversion. I am informed by Dr. Zouteveen that there is a case on record of a man having twenty-four fingers and twenty-four toes! I was chiefly led to the conclusion that the presence of supernumerary digits might be due to reversion from the fact that such digits, not only are strongly inherited, but, as I then believed, had the power of regrowth after amputation, like the normal digits of the lower vertebrata. But I have explained in the second edition of my Variation under Domestication why I now place little reliance on the recorded cases of such regrowth. Nevertheless it deserves notice, inasmuch as arrested development and reversion are intimately related processes; that various structures in an embryonic or arrested condition, such as a cleft palate, bifid uterus, etc., are frequently accompanied by polydactylism. This has been strongly insisted on by Meckel and Isidore Geoffroy St.-Hilaire. But at present it is the safest course to give up altogether the idea that there is any relation between the development of supernumerary digits and reversion to some lowly organised progenitor of man.) There are other cases which come more strictly under our present head of reversion. Certain structures, regularly occurring in the lower members of the group to which man belongs, occasionally make their appearance in him, though not found in the normal human embryo; or, if normally present in the human embryo, they become abnormally developed, although in a manner which is normal in the lower members of the group. These remarks will be rendered clearer by the following illustrations. In various mammals the uterus graduates from a double organ with two distinct orifices and two passages, as in the marsupials, into a single organ, which is in no way double except from having a slight internal fold, as in the higher apes and man. The rodents exhibit a perfect series of gradations between these two extreme states. In all mammals the uterus is developed from two simple primitive tubes, the inferior portions of which form the cornua; and it is in the words of Dr. Farre, "by the coalescence of the two cornua at their lower extremities that the body of the uterus is formed in man; while in those animals in which no middle portion or body exists, the cornua remain ununited. As the development of the uterus proceeds, the two cornua become gradually shorter, until at length they are lost, or, as it were, absorbed into the body of the uterus." The angles of the uterus are still produced into cornua, even in animals as high up in the scale as the lower apes and lemurs. Now in women, anomalous cases are not very infrequent, in which the mature uterus is furnished with cornua, or is partially divided into two organs; and such cases, according to Owen, repeat "the grade of concentrative development," attained by certain rodents. Here perhaps we have an instance of a simple arrest of embryonic development, with subsequent growth and perfect functional development; for either side of the partially double uterus is capable of performing the proper office of gestation. In other and rarer cases, two distinct uterine cavities are formed, each having its proper orifice and passage. (39. See Dr. A. Farre's well-known article in the 'Cyclopaedia of Anatomy and Physiology,' vol. v. 1859, p. 642. Owen, 'Anatomy of Vertebrates,' vol. iii. 1868, p. 687. Professor Turner, in 'Edinburgh Medical Journal,' February, 1865.) No such stage is passed through during the ordinary development of the embryo; and it is difficult to believe, though perhaps not impossible, that the two simple, minute, primitive tubes should know how (if such an expression may be used) to grow into two distinct uteri, each with a well-constructed orifice and passage, and each furnished with numerous muscles, nerves, glands and vessels, if they had not formerly passed through a similar course of development, as in the case of existing marsupials. No one will pretend that so perfect a structure as the abnormal double uterus in woman could be the result of mere chance. But the principle of reversion, by which a long-lost structure is called back into existence, might serve as the guide for its full development, even after the lapse of an enormous interval of time. Professor Canestrini, after discussing the foregoing and various analogous cases, arrives at the same conclusion as that just given. He adduces another instance, in the case of the malar bone (40. 'Annuario della Soc. dei Naturalisti,' Modena, 1867, p. 83. Prof. Canestrini gives extracts on this subject from various authorities. Laurillard remarks, that as he has found a complete similarity in the form, proportions, and connection of the two malar bones in several human subjects and in certain apes, he cannot consider this disposition of the parts as simply accidental. Another paper on this same anomaly has been published by Dr. Saviotti in the 'Gazzetta delle Cliniche,' Turin, 1871, where he says that traces of the division may be detected in about two per cent. of adult skulls; he also remarks that it more frequently occurs in prognathous skulls, not of the Aryan race, than in others. See also G. Delorenzi on the same subject; 'Tre nuovi casi d'anomalia dell' osso malare,' Torino, 1872. Also, E. Morselli, 'Sopra una rara anomalia dell' osso malare,' Modena, 1872. Still more recently Gruber has written a pamphlet on the division of this bone. I give these references because a reviewer, without any grounds or scruples, has thrown doubts on my statements.), which, in some of the Quadrumana and other mammals, normally consists of two portions. This is its condition in the human foetus when two months old; and through arrested development, it sometimes remains thus in man when adult, more especially in the lower prognathous races. Hence Canestrini concludes that some ancient progenitor of man must have had this bone normally divided into two portions, which afterwards became fused together. In man the frontal bone consists of a single piece, but in the embryo, and in children, and in almost all the lower mammals, it consists of two pieces separated by a distinct suture. This suture occasionally persists more or less distinctly in man after maturity; and more frequently in ancient than in recent crania, especially, as Canestrini has observed, in those exhumed from the Drift, and belonging to the brachycephalic type. Here again he comes to the same conclusion as in the analogous case of the malar bones. In this, and other instances presently to be given, the cause of ancient races approaching the lower animals in certain characters more frequently than do the modern races, appears to be, that the latter stand at a somewhat greater distance in the long line of descent from their early semi-human progenitors. Various other anomalies in man, more or less analogous to the foregoing, have been advanced by different authors, as cases of reversion; but these seem not a little doubtful, for we have to descend extremely low in the mammalian series, before we find such structures normally present. (41. A whole series of cases is given by Isidore Geoffroy St.-Hilaire, 'Hist. des Anomalies,' tom, iii, p. 437. A reviewer ('Journal of Anatomy and Physiology,' 1871, p. 366) blames me much for not having discussed the numerous cases, which have been recorded, of various parts arrested in their development. He says that, according to my theory, "every transient condition of an organ, during its development, is not only a means to an end, but once was an end in itself." This does not seem to me necessarily to hold good. Why should not variations occur during an early period of development, having no relation to reversion; yet such variations might be preserved and accumulated, if in any way serviceable, for instance, in shortening and simplifying the course of development? And again, why should not injurious abnormalities, such as atrophied or hypertrophied parts, which have no relation to a former state of existence, occur at an early period, as well as during maturity?) In man, the canine teeth are perfectly efficient instruments for mastication. But their true canine character, as Owen (42. 'Anatomy of Vertebrates,' vol. iii. 1868, p. 323.) remarks, "is indicated by the conical form of the crown, which terminates in an obtuse point, is convex outward and flat or sub-concave within, at the base of which surface there is a feeble prominence. The conical form is best expressed in the Melanian races, especially the Australian. The canine is more deeply implanted, and by a stronger fang than the incisors." Nevertheless, this tooth no longer serves man as a special weapon for tearing his enemies or prey; it may, therefore, as far as its proper function is concerned, be considered as rudimentary. In every large collection of human skulls some may be found, as Haeckel (43. 'Generelle Morphologie,' 1866, B. ii. s. clv.) observes, with the canine teeth projecting considerably beyond the others in the same manner as in the anthropomorphous apes, but in a less degree. In these cases, open spaces between the teeth in the one jaw are left for the reception of the canines of the opposite jaw. An inter-space of this kind in a Kaffir skull, figured by Wagner, is surprisingly wide. (44. Carl Vogt's 'Lectures on Man,' Eng. translat., 1864, p. 151.) Considering how few are the ancient skulls which have been examined, compared to recent skulls, it is an interesting fact that in at least three cases the canines project largely; and in the Naulette jaw they are spoken of as enormous. (45. C. Carter Blake, on a jaw from La Naulette, 'Anthropological Review,' 1867, p. 295. Schaaffhausen, ibid. 1868, p. 426.) Of the anthropomorphous apes the males alone have their canines fully developed; but in the female gorilla, and in a less degree in the female orang, these teeth project considerably beyond the others; therefore the fact, of which I have been assured, that women sometimes have considerably projecting canines, is no serious objection to the belief that their occasional great development in man is a case of reversion to an ape-like progenitor. He who rejects with scorn the belief that the shape of his own canines, and their occasional great development in other men, are due to our early forefathers having been provided with these formidable weapons, will probably reveal, by sneering, the line of his descent. For though he no longer intends, nor has the power, to use these teeth as weapons, he will unconsciously retract his "snarling muscles" (thus named by Sir C. Bell) (46. The Anatomy of Expression, 1844, pp. 110, 131.), so as to expose them ready for action, like a dog prepared to fight. Many muscles are occasionally developed in man, which are proper to the Quadrumana or other mammals. Professor Vlacovich (47. Quoted by Prof. Canestrini in the 'Annuario della Soc. dei Naturalisti,' 1867, p. 90.) examined forty male subjects, and found a muscle, called by him the ischio-pubic, in nineteen of them; in three others there was a ligament which represented this muscle; and in the remaining eighteen no trace of it. In only two out of thirty female subjects was this muscle developed on both sides, but in three others the rudimentary ligament was present. This muscle, therefore, appears to be much more common in the male than in the female sex; and on the belief in the descent of man from some lower form, the fact is intelligible; for it has been detected in several of the lower animals, and in all of these it serves exclusively to aid the male in the act of reproduction. Mr. J. Wood, in his valuable series of papers (48. These papers deserve careful study by any one who desires to learn how frequently our muscles vary, and in varying come to resemble those of the Quadrumana. The following references relate to the few points touched on in my text: 'Proc. Royal Soc.' vol. xiv. 1865, pp. 379-384; vol. xv. 1866, pp. 241, 242; vol. xv. 1867, p. 544; vol. xvi. 1868, p. 524. I may here add that Dr. Murie and Mr. St. George Mivart have shewn in their Memoir on the Lemuroidea ('Transactions, Zoological Society,' vol. vii. 1869, p. 96), how extraordinarily variable some of the muscles are in these animals, the lowest members of the Primates. Gradations, also, in the muscles leading to structures found in animals still lower in the scale, are numerous in the Lemuroidea.), has minutely described a vast number of muscular variations in man, which resemble normal structures in the lower animals. The muscles which closely resemble those regularly present in our nearest allies, the Quadrumana, are too numerous to be here even specified. In a single male subject, having a strong bodily frame, and well-formed skull, no less than seven muscular variations were observed, all of which plainly represented muscles proper to various kinds of apes. This man, for instance, had on both sides of his neck a true and powerful "levator claviculae," such as is found in all kinds of apes, and which is said to occur in about one out of sixty human subjects. (49. See also Prof. Macalister in 'Proceedings, Royal Irish Academy,' vol. x. 1868, p. 124.) Again, this man had "a special abductor of the metatarsal bone of the fifth digit, such as Professor Huxley and Mr. Flower have shewn to exist uniformly in the higher and lower apes." I will give only two additional cases; the acromio-basilar muscle is found in all mammals below man, and seems to be correlated with a quadrupedal gait, (50. Mr. Champneys in 'Journal of Anatomy and Physiology,' Nov. 1871, p. 178.) and it occurs in about one out of sixty human subjects. In the lower extremities Mr. Bradley (51. Ibid. May 1872, p. 421.) found an abductor ossis metatarsi quinti in both feet of man; this muscle had not up to that time been recorded in mankind, but is always present in the anthropomorphous apes. The muscles of the hands and arms--parts which are so eminently characteristic of man--are extremely liable to vary, so as to resemble the corresponding muscles in the lower animals. (52. Prof. Macalister (ibid. p. 121) has tabulated his observations, and finds that muscular abnormalities are most frequent in the fore-arms, secondly, in the face, thirdly, in the foot, etc.) Such resemblances are either perfect or imperfect; yet in the latter case they are manifestly of a transitional nature. Certain variations are more common in man, and others in woman, without our being able to assign any reason. Mr. Wood, after describing numerous variations, makes the following pregnant remark. "Notable departures from the ordinary type of the muscular structures run in grooves or directions, which must be taken to indicate some unknown factor, of much importance to a comprehensive knowledge of general and scientific anatomy." (53. The Rev. Dr. Haughton, after giving ('Proc. R. Irish Academy,' June 27, 1864, p. 715) a remarkable case of variation in the human flexor pollicis longus, adds, "This remarkable example shews that man may sometimes possess the arrangement of tendons of thumb and fingers characteristic of the macaque; but whether such a case should be regarded as a macaque passing upwards into a man, or a man passing downwards into a macaque, or as a congenital freak of nature, I cannot undertake to say." It is satisfactory to hear so capable an anatomist, and so embittered an opponent of evolutionism, admitting even the possibility of either of his first propositions. Prof. Macalister has also described ('Proceedings Royal Irish Academy,' vol. x. 1864, p. 138) variations in the flexor pollicis longus, remarkable from their relations to the same muscle in the Quadrumana.) That this unknown factor is reversion to a former state of existence may be admitted as in the highest degree probable. (54. Since the first edition of this book appeared, Mr. Wood has published another memoir in the Philosophical Transactions, 1870, p. 83, on the varieties of the muscles of the human neck, shoulder, and chest. He here shews how extremely variable these muscles are, and how often and how closely the variations resemble the normal muscles of the lower animals. He sums up by remarking, "It will be enough for my purpose if I have succeeded in shewing the more important forms which, when occurring as varieties in the human subject, tend to exhibit in a sufficiently marked manner what may be considered as proofs and examples of the Darwinian principle of reversion, or law of inheritance, in this department of anatomical science.") It is quite incredible that a man should through mere accident abnormally resemble certain apes in no less than seven of his muscles, if there had been no genetic connection between them. On the other hand, if man is descended from some ape-like creature, no valid reason can be assigned why certain muscles should not suddenly reappear after an interval of many thousand generations, in the same manner as with horses, asses, and mules, dark-coloured stripes suddenly reappear on the legs, and shoulders, after an interval of hundreds, or more probably of thousands of generations. These various cases of reversion are so closely related to those of rudimentary organs given in the first chapter, that many of them might have been indifferently introduced either there or here. Thus a human uterus furnished with cornua may be said to represent, in a rudimentary condition, the same organ in its normal state in certain mammals. Some parts which are rudimentary in man, as the os coccyx in both sexes, and the mammae in the male sex, are always present; whilst others, such as the supracondyloid foramen, only occasionally appear, and therefore might have been introduced under the head of reversion. These several reversionary structures, as well as the strictly rudimentary ones, reveal the descent of man from some lower form in an unmistakable manner. CORRELATED VARIATION. In man, as in the lower animals, many structures are so intimately related, that when one part varies so does another, without our being able, in most cases, to assign any reason. We cannot say whether the one part governs the other, or whether both are governed by some earlier developed part. Various monstrosities, as I. Geoffroy repeatedly insists, are thus intimately connected. Homologous structures are particularly liable to change together, as we see on the opposite sides of the body, and in the upper and lower extremities. Meckel long ago remarked, that when the muscles of the arm depart from their proper type, they almost always imitate those of the leg; and so, conversely, with the muscles of the legs. The organs of sight and hearing, the teeth and hair, the colour of the skin and of the hair, colour and constitution, are more or less correlated. (55. The authorities for these several statements are given in my 'Variation of Animals under Domestication,' vol. ii. pp. 320-335.) Professor Schaaffhausen first drew attention to the relation apparently existing between a muscular frame and the strongly-pronounced supra-orbital ridges, which are so characteristic of the lower races of man. Besides the variations which can be grouped with more or less probability under the foregoing heads, there is a large class of variations which may be provisionally called spontaneous, for to our ignorance they appear to arise without any exciting cause. It can, however, be shewn that such variations, whether consisting of slight individual differences, or of strongly-marked and abrupt deviations of structure, depend much more on the constitution of the organism than on the nature of the conditions to which it has been subjected. (56. This whole subject has been discussed in chap. xxiii. vol. ii. of my 'Variation of Animals and Plants under Domestication.') RATE OF INCREASE. Civilised populations have been known under favourable conditions, as in the United States, to double their numbers in twenty-five years; and, according to a calculation, by Euler, this might occur in a little over twelve years. (57. See the ever memorable 'Essay on the Principle of Population,' by the Rev. T. Malthus, vol. i. 1826. pp. 6, 517.) At the former rate, the present population of the United States (thirty millions), would in 657 years cover the whole terraqueous globe so thickly, that four men would have to stand on each square yard of surface. The primary or fundamental check to the continued increase of man is the difficulty of gaining subsistence, and of living in comfort. We may infer that this is the case from what we see, for instance, in the United States, where subsistence is easy, and there is plenty of room. If such means were suddenly doubled in Great Britain, our number would be quickly doubled. With civilised nations this primary check acts chiefly by restraining marriages. The greater death-rate of infants in the poorest classes is also very important; as well as the greater mortality, from various diseases, of the inhabitants of crowded and miserable houses, at all ages. The effects of severe epidemics and wars are soon counterbalanced, and more than counterbalanced, in nations placed under favourable conditions. Emigration also comes in aid as a temporary check, but, with the extremely poor classes, not to any great extent. There is reason to suspect, as Malthus has remarked, that the reproductive power is actually less in barbarous, than in civilised races. We know nothing positively on this head, for with savages no census has been taken; but from the concurrent testimony of missionaries, and of others who have long resided with such people, it appears that their families are usually small, and large ones rare. This may be partly accounted for, as it is believed, by the women suckling their infants during a long time; but it is highly probable that savages, who often suffer much hardship, and who do not obtain so much nutritious food as civilised men, would be actually less prolific. I have shewn in a former work (58. 'Variation of Animals and Plants under Domestication,' vol ii. pp. 111-113, 163.), that all our domesticated quadrupeds and birds, and all our cultivated plants, are more fertile than the corresponding species in a state of nature. It is no valid objection to this conclusion that animals suddenly supplied with an excess of food, or when grown very fat; and that most plants on sudden removal from very poor to very rich soil, are rendered more or less sterile. We might, therefore, expect that civilised men, who in one sense are highly domesticated, would be more prolific than wild men. It is also probable that the increased fertility of civilised nations would become, as with our domestic animals, an inherited character: it is at least known that with mankind a tendency to produce twins runs in families. (59. Mr. Sedgwick, 'British and Foreign Medico-Chirurgical Review,' July 1863, p. 170.) Notwithstanding that savages appear to be less prolific than civilised people, they would no doubt rapidly increase if their numbers were not by some means rigidly kept down. The Santali, or hill-tribes of India, have recently afforded a good illustration of this fact; for, as shewn by Mr. Hunter (60. 'The Annals of Rural Bengal,' by W.W. Hunter, 1868, p. 259.), they have increased at an extraordinary rate since vaccination has been introduced, other pestilences mitigated, and war sternly repressed. This increase, however, would not have been possible had not these rude people spread into the adjoining districts, and worked for hire. Savages almost always marry; yet there is some prudential restraint, for they do not commonly marry at the earliest possible age. The young men are often required to shew that they can support a wife; and they generally have first to earn the price with which to purchase her from her parents. With savages the difficulty of obtaining subsistence occasionally limits their number in a much more direct manner than with civilised people, for all tribes periodically suffer from severe famines. At such times savages are forced to devour much bad food, and their health can hardly fail to be injured. Many accounts have been published of their protruding stomachs and emaciated limbs after and during famines. They are then, also, compelled to wander much, and, as I was assured in Australia, their infants perish in large numbers. As famines are periodical, depending chiefly on extreme seasons, all tribes must fluctuate in number. They cannot steadily and regularly increase, as there is no artificial increase in the supply of food. Savages, when hard pressed, encroach on each other's territories, and war is the result; but they are indeed almost always at war with their neighbours. They are liable to many accidents on land and water in their search for food; and in some countries they suffer much from the larger beasts of prey. Even in India, districts have been depopulated by the ravages of tigers. Malthus has discussed these several checks, but he does not lay stress enough on what is probably the most important of all, namely infanticide, especially of female infants, and the habit of procuring abortion. These practices now prevail in many quarters of the world; and infanticide seems formerly to have prevailed, as Mr. M'Lennan (61. 'Primitive Marriage,' 1865.) has shewn, on a still more extensive scale. These practices appear to have originated in savages recognising the difficulty, or rather the impossibility of supporting all the infants that are born. Licentiousness may also be added to the foregoing checks; but this does not follow from failing means of subsistence; though there is reason to believe that in some cases (as in Japan) it has been intentionally encouraged as a means of keeping down the population. If we look back to an extremely remote epoch, before man had arrived at the dignity of manhood, he would have been guided more by instinct and less by reason than are the lowest savages at the present time. Our early semi-human progenitors would not have practised infanticide or polyandry; for the instincts of the lower animals are never so perverted (62. A writer in the 'Spectator' (March 12, 1871, p. 320) comments as follows on this passage:--"Mr. Darwin finds himself compelled to reintroduce a new doctrine of the fall of man. He shews that the instincts of the higher animals are far nobler than the habits of savage races of men, and he finds himself, therefore, compelled to re-introduce,--in a form of the substantial orthodoxy of which he appears to be quite unconscious,--and to introduce as a scientific hypothesis the doctrine that man's gain of KNOWLEDGE was the cause of a temporary but long-enduring moral deterioration as indicated by the many foul customs, especially as to marriage, of savage tribes. What does the Jewish tradition of the moral degeneration of man through his snatching at a knowledge forbidden him by his highest instinct assert beyond this?") as to lead them regularly to destroy their own offspring, or to be quite devoid of jealousy. There would have been no prudential restraint from marriage, and the sexes would have freely united at an early age. Hence the progenitors of man would have tended to increase rapidly; but checks of some kind, either periodical or constant, must have kept down their numbers, even more severely than with existing savages. What the precise nature of these checks were, we cannot say, any more than with most other animals. We know that horses and cattle, which are not extremely prolific animals, when first turned loose in South America, increased at an enormous rate. The elephant, the slowest breeder of all known animals, would in a few thousand years stock the whole world. The increase of every species of monkey must be checked by some means; but not, as Brehm remarks, by the attacks of beasts of prey. No one will assume that the actual power of reproduction in the wild horses and cattle of America, was at first in any sensible degree increased; or that, as each district became fully stocked, this same power was diminished. No doubt, in this case, and in all others, many checks concur, and different checks under different circumstances; periodical dearths, depending on unfavourable seasons, being probably the most important of all. So it will have been with the early progenitors of man. NATURAL SELECTION. We have now seen that man is variable in body and mind; and that the variations are induced, either directly or indirectly, by the same general causes, and obey the same general laws, as with the lower animals. Man has spread widely over the face of the earth, and must have been exposed, during his incessant migrations (63. See some good remarks to this effect by W. Stanley Jevons, "A Deduction from Darwin's Theory," 'Nature,' 1869, p. 231.), to the most diversified conditions. The inhabitants of Tierra del Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and of the arctic regions in the other, must have passed through many climates, and changed their habits many times, before they reached their present homes. (64. Latham, 'Man and his Migrations,' 1851, p. 135.) The early progenitors of man must also have tended, like all other animals, to have increased beyond their means of subsistence; they must, therefore, occasionally have been exposed to a struggle for existence, and consequently to the rigid law of natural selection. Beneficial variations of all kinds will thus, either occasionally or habitually, have been preserved and injurious ones eliminated. I do not refer to strongly-marked deviations of structure, which occur only at long intervals of time, but to mere individual differences. We know, for instance, that the muscles of our hands and feet, which determine our powers of movement, are liable, like those of the lower animals, (65. Messrs. Murie and Mivart in their 'Anatomy of the Lemuroidea' ('Transact. Zoolog. Soc.' vol. vii. 1869, pp. 96-98) say, "some muscles are so irregular in their distribution that they cannot be well classed in any of the above groups." These muscles differ even on the opposite sides of the same individual.) to incessant variability. If then the progenitors of man inhabiting any district, especially one undergoing some change in its conditions, were divided into two equal bodies, the one half which included all the individuals best adapted by their powers of movement for gaining subsistence, or for defending themselves, would on an average survive in greater numbers, and procreate more offspring than the other and less well endowed half. Man in the rudest state in which he now exists is the most dominant animal that has ever appeared on this earth. He has spread more widely than any other highly organised form: and all others have yielded before him. He manifestly owes this immense superiority to his intellectual faculties, to his social habits, which lead him to aid and defend his fellows, and to his corporeal structure. The supreme importance of these characters has been proved by the final arbitrament of the battle for life. Through his powers of intellect, articulate language has been evolved; and on this his wonderful advancement has mainly depended. As Mr. Chauncey Wright remarks (66. Limits of Natural Selection, 'North American Review,' Oct. 1870, p. 295.): "a psychological analysis of the faculty of language shews, that even the smallest proficiency in it might require more brain power than the greatest proficiency in any other direction." He has invented and is able to use various weapons, tools, traps, etc., with which he defends himself, kills or catches prey, and otherwise obtains food. He has made rafts or canoes for fishing or crossing over to neighbouring fertile islands. He has discovered the art of making fire, by which hard and stringy roots can be rendered digestible, and poisonous roots or herbs innocuous. This discovery of fire, probably the greatest ever made by man, excepting language, dates from before the dawn of history. These several inventions, by which man in the rudest state has become so pre-eminent, are the direct results of the development of his powers of observation, memory, curiosity, imagination, and reason. I cannot, therefore, understand how it is that Mr. Wallace (67. 'Quarterly Review,' April 1869, p. 392. This subject is more fully discussed in Mr. Wallace's 'Contributions to the Theory of Natural Selection,' 1870, in which all the essays referred to in this work are re-published. The 'Essay on Man,' has been ably criticised by Prof. Claparede, one of the most distinguished zoologists in Europe, in an article published in the 'Bibliotheque Universelle,' June 1870. The remark quoted in my text will surprise every one who has read Mr. Wallace's celebrated paper on 'The Origin of Human Races Deduced from the Theory of Natural Selection,' originally published in the 'Anthropological Review,' May 1864, p. clviii. I cannot here resist quoting a most just remark by Sir J. Lubbock ('Prehistoric Times,' 1865, p. 479) in reference to this paper, namely, that Mr. Wallace, "with characteristic unselfishness, ascribes it (i.e. the idea of natural selection) unreservedly to Mr. Darwin, although, as is well known, he struck out the idea independently, and published it, though not with the same elaboration, at the same time.") maintains, that "natural selection could only have endowed the savage with a brain a little superior to that of an ape." Although the intellectual powers and social habits of man are of paramount importance to him, we must not underrate the importance of his bodily structure, to which subject the remainder of this chapter will be devoted; the development of the intellectual and social or moral faculties being discussed in a later chapter. Even to hammer with precision is no easy matter, as every one who has tried to learn carpentry will admit. To throw a stone with as true an aim as a Fuegian in defending himself, or in killing birds, requires the most consummate perfection in the correlated action of the muscles of the hand, arm, and shoulder, and, further, a fine sense of touch. In throwing a stone or spear, and in many other actions, a man must stand firmly on his feet; and this again demands the perfect co-adaptation of numerous muscles. To chip a flint into the rudest tool, or to form a barbed spear or hook from a bone, demands the use of a perfect hand; for, as a most capable judge, Mr. Schoolcraft (68. Quoted by Mr. Lawson Tait in his 'Law of Natural Selection,' 'Dublin Quarterly Journal of Medical Science,' Feb. 1869. Dr. Keller is likewise quoted to the same effect.), remarks, the shaping fragments of stone into knives, lances, or arrow-heads, shews "extraordinary ability and long practice." This is to a great extent proved by the fact that primeval men practised a division of labour; each man did not manufacture his own flint tools or rude pottery, but certain individuals appear to have devoted themselves to such work, no doubt receiving in exchange the produce of the chase. Archaeologists are convinced that an enormous interval of time elapsed before our ancestors thought of grinding chipped flints into smooth tools. One can hardly doubt, that a man-like animal who possessed a hand and arm sufficiently perfect to throw a stone with precision, or to form a flint into a rude tool, could, with sufficient practice, as far as mechanical skill alone is concerned, make almost anything which a civilised man can make. The structure of the hand in this respect may be compared with that of the vocal organs, which in the apes are used for uttering various signal-cries, or, as in one genus, musical cadences; but in man the closely similar vocal organs have become adapted through the inherited effects of use for the utterance of articulate language. Turning now to the nearest allies of men, and therefore to the best representatives of our early progenitors, we find that the hands of the Quadrumana are constructed on the same general pattern as our own, but are far less perfectly adapted for diversified uses. Their hands do not serve for locomotion so well as the feet of a dog; as may be seen in such monkeys as the chimpanzee and orang, which walk on the outer margins of the palms, or on the knuckles. (69. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 71.) Their hands, however, are admirably adapted for climbing trees. Monkeys seize thin branches or ropes, with the thumb on one side and the fingers and palm on the other, in the same manner as we do. They can thus also lift rather large objects, such as the neck of a bottle, to their mouths. Baboons turn over stones, and scratch up roots with their hands. They seize nuts, insects, or other small objects with the thumb in opposition to the fingers, and no doubt they thus extract eggs and young from the nests of birds. American monkeys beat the wild oranges on the branches until the rind is cracked, and then tear it off with the fingers of the two hands. In a wild state they break open hard fruits with stones. Other monkeys open mussel-shells with the two thumbs. With their fingers they pull out thorns and burs, and hunt for each other's parasites. They roll down stones, or throw them at their enemies: nevertheless, they are clumsy in these various actions, and, as I have myself seen, are quite unable to throw a stone with precision. It seems to me far from true that because "objects are grasped clumsily" by monkeys, "a much less specialised organ of prehension" would have served them (70. 'Quarterly Review,' April 1869, p. 392.) equally well with their present hands. On the contrary, I see no reason to doubt that more perfectly constructed hands would have been an advantage to them, provided that they were not thus rendered less fitted for climbing trees. We may suspect that a hand as perfect as that of man would have been disadvantageous for climbing; for the most arboreal monkeys in the world, namely, Ateles in America, Colobus in Africa, and Hylobates in Asia, are either thumbless, or their toes partially cohere, so that their limbs are converted into mere grasping hooks. (71. In Hylobates syndactylus, as the name expresses, two of the toes regularly cohere; and this, as Mr. Blyth informs me, is occasionally the case with the toes of H. agilis, lar, and leuciscus. Colobus is strictly arboreal and extraordinarily active (Brehm, 'Thierleben,' B. i. s. 50), but whether a better climber than the species of the allied genera, I do not know. It deserves notice that the feet of the sloths, the most arboreal animals in the world, are wonderfully hook-like. As soon as some ancient member in the great series of the Primates came to be less arboreal, owing to a change in its manner of procuring subsistence, or to some change in the surrounding conditions, its habitual manner of progression would have been modified: and thus it would have been rendered more strictly quadrupedal or bipedal. Baboons frequent hilly and rocky districts, and only from necessity climb high trees (72. Brehm, 'Thierleben,' B. i. s. 80.); and they have acquired almost the gait of a dog. Man alone has become a biped; and we can, I think, partly see how he has come to assume his erect attitude, which forms one of his most conspicuous characters. Man could not have attained his present dominant position in the world without the use of his hands, which are so admirably adapted to act in obedience to his will. Sir C. Bell (73. 'The Hand,' etc., 'Bridgewater Treatise,' 1833, p. 38.) insists that "the hand supplies all instruments, and by its correspondence with the intellect gives him universal dominion." But the hands and arms could hardly have become perfect enough to have manufactured weapons, or to have hurled stones and spears with a true aim, as long as they were habitually used for locomotion and for supporting the whole weight of the body, or, as before remarked, so long as they were especially fitted for climbing trees. Such rough treatment would also have blunted the sense of touch, on which their delicate use largely depends. From these causes alone it would have been an advantage to man to become a biped; but for many actions it is indispensable that the arms and whole upper part of the body should be free; and he must for this end stand firmly on his feet. To gain this great advantage, the feet have been rendered flat; and the great toe has been peculiarly modified, though this has entailed the almost complete loss of its power of prehension. It accords with the principle of the division of physiological labour, prevailing throughout the animal kingdom, that as the hands became perfected for prehension, the feet should have become perfected for support and locomotion. With some savages, however, the foot has not altogether lost its prehensile power, as shewn by their manner of climbing trees, and of using them in other ways. (74. Haeckel has an excellent discussion on the steps by which man became a biped: 'Natürliche Schöpfungsgeschichte,' 1868, s. 507. Dr. Buchner ('Conférences sur la Théorie Darwinienne,' 1869, p. 135) has given good cases of the use of the foot as a prehensile organ by man; and has also written on the manner of progression of the higher apes, to which I allude in the following paragraph: see also Owen ('Anatomy of Vertebrates,' vol. iii. p. 71) on this latter subject.) If it be an advantage to man to stand firmly on his feet and to have his hands and arms free, of which, from his pre-eminent success in the battle of life there can be no doubt, then I can see no reason why it should not have been advantageous to the progenitors of man to have become more and more erect or bipedal. They would thus have been better able to defend themselves with stones or clubs, to attack their prey, or otherwise to obtain food. The best built individuals would in the long run have succeeded best, and have survived in larger numbers. If the gorilla and a few allied forms had become extinct, it might have been argued, with great force and apparent truth, that an animal could not have been gradually converted from a quadruped into a biped, as all the individuals in an intermediate condition would have been miserably ill-fitted for progression. But we know (and this is well worthy of reflection) that the anthropomorphous apes are now actually in an intermediate condition; and no one doubts that they are on the whole well adapted for their conditions of life. Thus the gorilla runs with a sidelong shambling gait, but more commonly progresses by resting on its bent hands. The long-armed apes occasionally use their arms like crutches, swinging their bodies forward between them, and some kinds of Hylobates, without having been taught, can walk or run upright with tolerable quickness; yet they move awkwardly, and much less securely than man. We see, in short, in existing monkeys a manner of progression intermediate between that of a quadruped and a biped; but, as an unprejudiced judge (75. Prof. Broca, La Constitution des Vertèbres caudales; 'La Revue d'Anthropologie,' 1872, p. 26, (separate copy).) insists, the anthropomorphous apes approach in structure more nearly to the bipedal than to the quadrupedal type. As the progenitors of man became more and more erect, with their hands and arms more and more modified for prehension and other purposes, with their feet and legs at the same time transformed for firm support and progression, endless other changes of structure would have become necessary. The pelvis would have to be broadened, the spine peculiarly curved, and the head fixed in an altered position, all which changes have been attained by man. Prof. Schaaffhausen (76. 'On the Primitive Form of the Skull,' translated in 'Anthropological Review,' Oct. 1868, p. 428. Owen ('Anatomy of Vertebrates,' vol. ii. 1866, p. 551) on the mastoid processes in the higher apes.) maintains that "the powerful mastoid processes of the human skull are the result of his erect position;" and these processes are absent in the orang, chimpanzee, etc., and are smaller in the gorilla than in man. Various other structures, which appear connected with man's erect position, might here have been added. It is very difficult to decide how far these correlated modifications are the result of natural selection, and how far of the inherited effects of the increased use of certain parts, or of the action of one part on another. No doubt these means of change often co-operate: thus when certain muscles, and the crests of bone to which they are attached, become enlarged by habitual use, this shews that certain actions are habitually performed and must be serviceable. Hence the individuals which performed them best, would tend to survive in greater numbers. The free use of the arms and hands, partly the cause and partly the result of man's erect position, appears to have led in an indirect manner to other modifications of structure. The early male forefathers of man were, as previously stated, probably furnished with great canine teeth; but as they gradually acquired the habit of using stones, clubs, or other weapons, for fighting with their enemies or rivals, they would use their jaws and teeth less and less. In this case, the jaws, together with the teeth, would become reduced in size, as we may feel almost sure from innumerable analogous cases. In a future chapter we shall meet with a closely parallel case, in the reduction or complete disappearance of the canine teeth in male ruminants, apparently in relation with the development of their horns; and in horses, in relation to their habit of fighting with their incisor teeth and hoofs. In the adult male anthropomorphous apes, as Rutimeyer (77. 'Die Grenzen der Thierwelt, eine Betrachtung zu Darwin's Lehre,' 1868, s. 51.), and others, have insisted, it is the effect on the skull of the great development of the jaw-muscles that causes it to differ so greatly in many respects from that of man, and has given to these animals "a truly frightful physiognomy." Therefore, as the jaws and teeth in man's progenitors gradually become reduced in size, the adult skull would have come to resemble more and more that of existing man. As we shall hereafter see, a great reduction of the canine teeth in the males would almost certainly affect the teeth of the females through inheritance. As the various mental faculties gradually developed themselves the brain would almost certainly become larger. No one, I presume, doubts that the large proportion which the size of man's brain bears to his body, compared to the same proportion in the gorilla or orang, is closely connected with his higher mental powers. We meet with closely analogous facts with insects, for in ants the cerebral ganglia are of extraordinary dimensions, and in all the Hymenoptera these ganglia are many times larger than in the less intelligent orders, such as beetles. (78. Dujardin, 'Annales des Sciences Nat.' 3rd series, Zoolog., tom. xiv. 1850, p. 203. See also Mr. Lowne, 'Anatomy and Phys. of the Musca vomitoria,' 1870, p. 14. My son, Mr. F. Darwin, dissected for me the cerebral ganglia of the Formica rufa.) On the other hand, no one supposes that the intellect of any two animals or of any two men can be accurately gauged by the cubic contents of their skulls. It is certain that there may be extraordinary mental activity with an extremely small absolute mass of nervous matter: thus the wonderfully diversified instincts, mental powers, and affections of ants are notorious, yet their cerebral ganglia are not so large as the quarter of a small pin's head. Under this point of view, the brain of an ant is one of the most marvellous atoms of matter in the world, perhaps more so than the brain of a man. The belief that there exists in man some close relation between the size of the brain and the development of the intellectual faculties is supported by the comparison of the skulls of savage and civilised races, of ancient and modern people, and by the analogy of the whole vertebrate series. Dr. J. Barnard Davis has proved (79. 'Philosophical Transactions,' 1869, p. 513.), by many careful measurements, that the mean internal capacity of the skull in Europeans is 92.3 cubic inches; in Americans 87.5; in Asiatics 87.1; and in Australians only 81.9 cubic inches. Professor Broca (80. 'Les Selections,' M. P. Broca, 'Revue d'Anthropologies,' 1873; see also, as quoted in C. Vogt's 'Lectures on Man,' Engl. translat., 1864, pp. 88, 90. Prichard, 'Physical History of Mankind,' vol. i. 1838, p. 305.) found that the nineteenth century skulls from graves in Paris were larger than those from vaults of the twelfth century, in the proportion of 1484 to 1426; and that the increased size, as ascertained by measurements, was exclusively in the frontal part of the skull--the seat of the intellectual faculties. Prichard is persuaded that the present inhabitants of Britain have "much more capacious brain-cases" than the ancient inhabitants. Nevertheless, it must be admitted that some skulls of very high antiquity, such as the famous one of Neanderthal, are well developed and capacious. (81. In the interesting article just referred to, Prof. Broca has well remarked, that in civilised nations, the average capacity of the skull must be lowered by the preservation of a considerable number of individuals, weak in mind and body, who would have been promptly eliminated in the savage state. On the other hand, with savages, the average includes only the more capable individuals, who have been able to survive under extremely hard conditions of life. Broca thus explains the otherwise inexplicable fact, that the mean capacity of the skull of the ancient Troglodytes of Lozere is greater than that of modern Frenchmen.) With respect to the lower animals, M.E. Lartet (82. 'Comptes-rendus des Sciences,' etc., June 1, 1868.), by comparing the crania of tertiary and recent mammals belonging to the same groups, has come to the remarkable conclusion that the brain is generally larger and the convolutions are more complex in the more recent forms. On the other hand, I have shewn (83. The 'Variation of Animals and Plants under Domestication,' vol. i. pp. 124-129.) that the brains of domestic rabbits are considerably reduced in bulk, in comparison with those of the wild rabbit or hare; and this may be attributed to their having been closely confined during many generations, so that they have exerted their intellect, instincts, senses and voluntary movements but little. The gradually increasing weight of the brain and skull in man must have influenced the development of the supporting spinal column, more especially whilst he was becoming erect. As this change of position was being brought about, the internal pressure of the brain will also have influenced the form of the skull; for many facts shew how easily the skull is thus affected. Ethnologists believe that it is modified by the kind of cradle in which infants sleep. Habitual spasms of the muscles, and a cicatrix from a severe burn, have permanently modified the facial bones. In young persons whose heads have become fixed either sideways or backwards, owing to disease, one of the two eyes has changed its position, and the shape of the skull has been altered apparently by the pressure of the brain in a new direction. (84. Schaaffhausen gives from Blumenbach and Busch, the cases of the spasms and cicatrix, in 'Anthropological Review,' Oct. 1868, p. 420. Dr. Jarrold ('Anthropologia,' 1808, pp. 115, 116) adduces from Camper and from his own observations, cases of the modification of the skull from the head being fixed in an unnatural position. He believes that in certain trades, such as that of a shoemaker, where the head is habitually held forward, the forehead becomes more rounded and prominent.) I have shewn that with long-eared rabbits even so trifling a cause as the lopping forward of one ear drags forward almost every bone of the skull on that side; so that the bones on the opposite side no longer strictly correspond. Lastly, if any animal were to increase or diminish much in general size, without any change in its mental powers, or if the mental powers were to be much increased or diminished, without any great change in the size of the body, the shape of the skull would almost certainly be altered. I infer this from my observations on domestic rabbits, some kinds of which have become very much larger than the wild animal, whilst others have retained nearly the same size, but in both cases the brain has been much reduced relatively to the size of the body. Now I was at first much surprised on finding that in all these rabbits the skull had become elongated or dolichocephalic; for instance, of two skulls of nearly equal breadth, the one from a wild rabbit and the other from a large domestic kind, the former was 3.15 and the latter 4.3 inches in length. (85. 'Variation of Animals and Plants under Domestication,' vol. i. p. 117, on the elongation of the skull; p. 119, on the effect of the lopping of one ear.) One of the most marked distinctions in different races of men is that the skull in some is elongated, and in others rounded; and here the explanation suggested by the case of the rabbits may hold good; for Welcker finds that short "men incline more to brachycephaly, and tall men to dolichocephaly" (86. Quoted by Schaaffhausen, in 'Anthropological Review,' Oct. 1868, p. 419.); and tall men may be compared with the larger and longer-bodied rabbits, all of which have elongated skulls or are dolichocephalic. From these several facts we can understand, to a certain extent, the means by which the great size and more or less rounded form of the skull have been acquired by man; and these are characters eminently distinctive of him in comparison with the lower animals. Another most conspicuous difference between man and the lower animals is the nakedness of his skin. Whales and porpoises (Cetacea), dugongs (Sirenia) and the hippopotamus are naked; and this may be advantageous to them for gliding through the water; nor would it be injurious to them from the loss of warmth, as the species, which inhabit the colder regions, are protected by a thick layer of blubber, serving the same purpose as the fur of seals and otters. Elephants and rhinoceroses are almost hairless; and as certain extinct species, which formerly lived under an Arctic climate, were covered with long wool or hair, it would almost appear as if the existing species of both genera had lost their hairy covering from exposure to heat. This appears the more probable, as the elephants in India which live on elevated and cool districts are more hairy (87. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 619.) than those on the lowlands. May we then infer that man became divested of hair from having aboriginally inhabited some tropical land? That the hair is chiefly retained in the male sex on the chest and face, and in both sexes at the junction of all four limbs with the trunk, favours this inference--on the assumption that the hair was lost before man became erect; for the parts which now retain most hair would then have been most protected from the heat of the sun. The crown of the head, however, offers a curious exception, for at all times it must have been one of the most exposed parts, yet it is thickly clothed with hair. The fact, however, that the other members of the order of Primates, to which man belongs, although inhabiting various hot regions, are well clothed with hair, generally thickest on the upper surface (88. Isidore Geoffroy St.-Hilaire remarks ('Histoire Nat. Generale,' tom. ii. 1859, pp. 215-217) on the head of man being covered with long hair; also on the upper surfaces of monkeys and of other mammals being more thickly clothed than the lower surfaces. This has likewise been observed by various authors. Prof. P. Gervais ('Histoire Nat. des Mammifères,' tom. i. 1854, p. 28), however, states that in the Gorilla the hair is thinner on the back, where it is partly rubbed off, than on the lower surface.), is opposed to the supposition that man became naked through the action of the sun. Mr. Belt believes (89. The 'Naturalist in Nicaragua,' 1874, p. 209. As some confirmation of Mr. Belt's view, I may quote the following passage from Sir W. Denison ('Varieties of Vice-Regal Life,' vol. i. 1870, p. 440): "It is said to be a practice with the Australians, when the vermin get troublesome, to singe themselves.") that within the tropics it is an advantage to man to be destitute of hair, as he is thus enabled to free himself of the multitude of ticks (acari) and other parasites, with which he is often infested, and which sometimes cause ulceration. But whether this evil is of sufficient magnitude to have led to the denudation of his body through natural selection, may be doubted, since none of the many quadrupeds inhabiting the tropics have, as far as I know, acquired any specialised means of relief. The view which seems to me the most probable is that man, or rather primarily woman, became divested of hair for ornamental purposes, as we shall see under Sexual Selection; and, according to this belief, it is not surprising that man should differ so greatly in hairiness from all other Primates, for characters, gained through sexual selection, often differ to an extraordinary degree in closely related forms. According to a popular impression, the absence of a tail is eminently distinctive of man; but as those apes which come nearest to him are destitute of this organ, its disappearance does not relate exclusively to man. The tail often differs remarkably in length within the same genus: thus in some species of Macacus it is longer than the whole body, and is formed of twenty-four vertebrae; in others it consists of a scarcely visible stump, containing only three or four vertebrae. In some kinds of baboons there are twenty-five, whilst in the mandrill there are ten very small stunted caudal vertebrae, or, according to Cuvier (90. Mr. St. George Mivart, 'Proc. Zoolog. Soc.' 1865, pp. 562, 583. Dr. J.E. Gray, 'Cat. Brit. Mus.: 'Skeletons.' Owen, 'Anatomy of Vertebrates,' vol. ii. p. 517. Isidore Geoffroy, 'Hist. Nat. Gen.' tom. ii. p. 244.), sometimes only five. The tail, whether it be long or short, almost always tapers towards the end; and this, I presume, results from the atrophy of the terminal muscles, together with their arteries and nerves, through disuse, leading to the atrophy of the terminal bones. But no explanation can at present be given of the great diversity which often occurs in its length. Here, however, we are more specially concerned with the complete external disappearance of the tail. Professor Broca has recently shewn (91. 'Revue d'Anthropologie,' 1872; 'La Constitution des vertèbres caudales.') that the tail in all quadrupeds consists of two portions, generally separated abruptly from each other; the basal portion consists of vertebrae, more or less perfectly channelled and furnished with apophyses like ordinary vertebrae; whereas those of the terminal portion are not channelled, are almost smooth, and scarcely resemble true vertebrae. A tail, though not externally visible, is really present in man and the anthropomorphous apes, and is constructed on exactly the same pattern in both. In the terminal portion the vertebrae, constituting the os coccyx, are quite rudimentary, being much reduced in size and number. In the basal portion, the vertebrae are likewise few, are united firmly together, and are arrested in development; but they have been rendered much broader and flatter than the corresponding vertebrae in the tails of other animals: they constitute what Broca calls the accessory sacral vertebrae. These are of functional importance by supporting certain internal parts and in other ways; and their modification is directly connected with the erect or semi-erect attitude of man and the anthropomorphous apes. This conclusion is the more trustworthy, as Broca formerly held a different view, which he has now abandoned. The modification, therefore, of the basal caudal vertebrae in man and the higher apes may have been effected, directly or indirectly, through natural selection. But what are we to say about the rudimentary and variable vertebrae of the terminal portion of the tail, forming the os coccyx? A notion which has often been, and will no doubt again be ridiculed, namely, that friction has had something to do with the disappearance of the external portion of the tail, is not so ridiculous as it at first appears. Dr. Anderson (92. 'Proceedings Zoological Society,' 1872, p. 210.) states that the extremely short tail of Macacus brunneus is formed of eleven vertebrae, including the imbedded basal ones. The extremity is tendinous and contains no vertebrae; this is succeeded by five rudimentary ones, so minute that together they are only one line and a half in length, and these are permanently bent to one side in the shape of a hook. The free part of the tail, only a little above an inch in length, includes only four more small vertebrae. This short tail is carried erect; but about a quarter of its total length is doubled on to itself to the left; and this terminal part, which includes the hook-like portion, serves "to fill up the interspace between the upper divergent portion of the callosities;" so that the animal sits on it, and thus renders it rough and callous. Dr. Anderson thus sums up his observations: "These facts seem to me to have only one explanation; this tail, from its short size, is in the monkey's way when it sits down, and frequently becomes placed under the animal while it is in this attitude; and from the circumstance that it does not extend beyond the extremity of the ischial tuberosities, it seems as if the tail originally had been bent round by the will of the animal, into the interspace between the callosities, to escape being pressed between them and the ground, and that in time the curvature became permanent, fitting in of itself when the organ happens to be sat upon." Under these circumstances it is not surprising that the surface of the tail should have been roughened and rendered callous, and Dr. Murie (93. 'Proceedings Zoological Society,' 1872, p. 786.), who carefully observed this species in the Zoological Gardens, as well as three other closely allied forms with slightly longer tails, says that when the animal sits down, the tail "is necessarily thrust to one side of the buttocks; and whether long or short its root is consequently liable to be rubbed or chafed." As we now have evidence that mutilations occasionally produce an inherited effect (94. I allude to Dr. Brown-Sequard's observations on the transmitted effect of an operation causing epilepsy in guinea-pigs, and likewise more recently on the analogous effects of cutting the sympathetic nerve in the neck. I shall hereafter have occasion to refer to Mr. Salvin's interesting case of the apparently inherited effects of mot-mots biting off the barbs of their own tail-feathers. See also on the general subject 'Variation of Animals and Plants under Domestication,' vol. ii. pp. 22-24.), it is not very improbable that in short-tailed monkeys, the projecting part of the tail, being functionally useless, should after many generations have become rudimentary and distorted, from being continually rubbed and chafed. We see the projecting part in this condition in the Macacus brunneus, and absolutely aborted in the M. ecaudatus and in several of the higher apes. Finally, then, as far as we can judge, the tail has disappeared in man and the anthropomorphous apes, owing to the terminal portion having been injured by friction during a long lapse of time; the basal and embedded portion having been reduced and modified, so as to become suitable to the erect or semi-erect position. I have now endeavoured to shew that some of the most distinctive characters of man have in all probability been acquired, either directly, or more commonly indirectly, through natural selection. We should bear in mind that modifications in structure or constitution which do not serve to adapt an organism to its habits of life, to the food which it consumes, or passively to the surrounding conditions, cannot have been thus acquired. We must not, however, be too confident in deciding what modifications are of service to each being: we should remember how little we know about the use of many parts, or what changes in the blood or tissues may serve to fit an organism for a new climate or new kinds of food. Nor must we forget the principle of correlation, by which, as Isidore Geoffroy has shewn in the case of man, many strange deviations of structure are tied together. Independently of correlation, a change in one part often leads, through the increased or decreased use of other parts, to other changes of a quite unexpected nature. It is also well to reflect on such facts, as the wonderful growth of galls on plants caused by the poison of an insect, and on the remarkable changes of colour in the plumage of parrots when fed on certain fishes, or inoculated with the poison of toads (95. The 'Variation of Animals and Plants under Domestication,' vol. ii. pp. 280, 282.); for we can thus see that the fluids of the system, if altered for some special purpose, might induce other changes. We should especially bear in mind that modifications acquired and continually used during past ages for some useful purpose, would probably become firmly fixed, and might be long inherited. Thus a large yet undefined extension may safely be given to the direct and indirect results of natural selection; but I now admit, after reading the essay by Nageli on plants, and the remarks by various authors with respect to animals, more especially those recently made by Professor Broca, that in the earlier editions of my 'Origin of Species' I perhaps attributed too much to the action of natural selection or the survival of the fittest. I have altered the fifth edition of the 'Origin' so as to confine my remarks to adaptive changes of structure; but I am convinced, from the light gained during even the last few years, that very many structures which now appear to us useless, will hereafter be proved to be useful, and will therefore come within the range of natural selection. Nevertheless, I did not formerly consider sufficiently the existence of structures, which, as far as we can at present judge, are neither beneficial nor injurious; and this I believe to be one of the greatest oversights as yet detected in my work. I may be permitted to say, as some excuse, that I had two distinct objects in view; firstly, to shew that species had not been separately created, and secondly, that natural selection had been the chief agent of change, though largely aided by the inherited effects of habit, and slightly by the direct action of the surrounding conditions. I was not, however, able to annul the influence of my former belief, then almost universal, that each species had been purposely created; and this led to my tacit assumption that every detail of structure, excepting rudiments, was of some special, though unrecognised, service. Any one with this assumption in his mind would naturally extend too far the action of natural selection, either during past or present times. Some of those who admit the principle of evolution, but reject natural selection, seem to forget, when criticising my book, that I had the above two objects in view; hence if I have erred in giving to natural selection great power, which I am very far from admitting, or in having exaggerated its power, which is in itself probable, I have at least, as I hope, done good service in aiding to overthrow the dogma of separate creations. It is, as I can now see, probable that all organic beings, including man, possess peculiarities of structure, which neither are now, nor were formerly of any service to them, and which, therefore, are of no physiological importance. We know not what produces the numberless slight differences between the individuals of each species, for reversion only carries the problem a few steps backwards, but each peculiarity must have had its efficient cause. If these causes, whatever they may be, were to act more uniformly and energetically during a lengthened period (and against this no reason can be assigned), the result would probably be not a mere slight individual difference, but a well-marked and constant modification, though one of no physiological importance. Changed structures, which are in no way beneficial, cannot be kept uniform through natural selection, though the injurious will be thus eliminated. Uniformity of character would, however, naturally follow from the assumed uniformity of the exciting causes, and likewise from the free intercrossing of many individuals. During successive periods, the same organism might in this manner acquire successive modifications, which would be transmitted in a nearly uniform state as long as the exciting causes remained the same and there was free intercrossing. With respect to the exciting causes we can only say, as when speaking of so-called spontaneous variations, that they relate much more closely to the constitution of the varying organism, than to the nature of the conditions to which it has been subjected. CONCLUSION. In this chapter we have seen that as man at the present day is liable, like every other animal, to multiform individual differences or slight variations, so no doubt were the early progenitors of man; the variations being formerly induced by the same general causes, and governed by the same general and complex laws as at present. As all animals tend to multiply beyond their means of subsistence, so it must have been with the progenitors of man; and this would inevitably lead to a struggle for existence and to natural selection. The latter process would be greatly aided by the inherited effects of the increased use of parts, and these two processes would incessantly react on each other. It appears, also, as we shall hereafter see, that various unimportant characters have been acquired by man through sexual selection. An unexplained residuum of change must be left to the assumed uniform action of those unknown agencies, which occasionally induce strongly marked and abrupt deviations of structure in our domestic productions. Judging from the habits of savages and of the greater number of the Quadrumana, primeval men, and even their ape-like progenitors, probably lived in society. With strictly social animals, natural selection sometimes acts on the individual, through the preservation of variations which are beneficial to the community. A community which includes a large number of well-endowed individuals increases in number, and is victorious over other less favoured ones; even although each separate member gains no advantage over the others of the same community. Associated insects have thus acquired many remarkable structures, which are of little or no service to the individual, such as the pollen-collecting apparatus, or the sting of the worker-bee, or the great jaws of soldier-ants. With the higher social animals, I am not aware that any structure has been modified solely for the good of the community, though some are of secondary service to it. For instance, the horns of ruminants and the great canine teeth of baboons appear to have been acquired by the males as weapons for sexual strife, but they are used in defence of the herd or troop. In regard to certain mental powers the case, as we shall see in the fifth chapter, is wholly different; for these faculties have been chiefly, or even exclusively, gained for the benefit of the community, and the individuals thereof have at the same time gained an advantage indirectly. It has often been objected to such views as the foregoing, that man is one of the most helpless and defenceless creatures in the world; and that during his early and less well-developed condition, he would have been still more helpless. The Duke of Argyll, for instance, insists (96. 'Primeval Man,' 1869, p. 66.) that "the human frame has diverged from the structure of brutes, in the direction of greater physical helplessness and weakness. That is to say, it is a divergence which of all others it is most impossible to ascribe to mere natural selection." He adduces the naked and unprotected state of the body, the absence of great teeth or claws for defence, the small strength and speed of man, and his slight power of discovering food or of avoiding danger by smell. To these deficiencies there might be added one still more serious, namely, that he cannot climb quickly, and so escape from enemies. The loss of hair would not have been a great injury to the inhabitants of a warm country. For we know that the unclothed Fuegians can exist under a wretched climate. When we compare the defenceless state of man with that of apes, we must remember that the great canine teeth with which the latter are provided, are possessed in their full development by the males alone, and are chiefly used by them for fighting with their rivals; yet the females, which are not thus provided, manage to survive. In regard to bodily size or strength, we do not know whether man is descended from some small species, like the chimpanzee, or from one as powerful as the gorilla; and, therefore, we cannot say whether man has become larger and stronger, or smaller and weaker, than his ancestors. We should, however, bear in mind that an animal possessing great size, strength, and ferocity, and which, like the gorilla, could defend itself from all enemies, would not perhaps have become social: and this would most effectually have checked the acquirement of the higher mental qualities, such as sympathy and the love of his fellows. Hence it might have been an immense advantage to man to have sprung from some comparatively weak creature. The small strength and speed of man, his want of natural weapons, etc., are more than counterbalanced, firstly, by his intellectual powers, through which he has formed for himself weapons, tools, etc., though still remaining in a barbarous state, and, secondly, by his social qualities which lead him to give and receive aid from his fellow-men. No country in the world abounds in a greater degree with dangerous beasts than Southern Africa; no country presents more fearful physical hardships than the Arctic regions; yet one of the puniest of races, that of the Bushmen, maintains itself in Southern Africa, as do the dwarfed Esquimaux in the Arctic regions. The ancestors of man were, no doubt, inferior in intellect, and probably in social disposition, to the lowest existing savages; but it is quite conceivable that they might have existed, or even flourished, if they had advanced in intellect, whilst gradually losing their brute-like powers, such as that of climbing trees, etc. But these ancestors would not have been exposed to any special danger, even if far more helpless and defenceless than any existing savages, had they inhabited some warm continent or large island, such as Australia, New Guinea, or Borneo, which is now the home of the orang. And natural selection arising from the competition of tribe with tribe, in some such large area as one of these, together with the inherited effects of habit, would, under favourable conditions, have sufficed to raise man to his present high position in the organic scale. CHAPTER III. COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS. The difference in mental power between the highest ape and the lowest savage, immense--Certain instincts in common--The emotions--Curiosity--Imitation--Attention--Memory--Imagination--Reason--Progressive improvement --Tools and weapons used by animals--Abstraction, Self-consciousness--Language--Sense of beauty--Belief in God, spiritual agencies, superstitions. We have seen in the last two chapters that man bears in his bodily structure clear traces of his descent from some lower form; but it may be urged that, as man differs so greatly in his mental power from all other animals, there must be some error in this conclusion. No doubt the difference in this respect is enormous, even if we compare the mind of one of the lowest savages, who has no words to express any number higher than four, and who uses hardly any abstract terms for common objects or for the affections (1. See the evidence on those points, as given by Lubbock, 'Prehistoric Times,' p. 354, etc.), with that of the most highly organised ape. The difference would, no doubt, still remain immense, even if one of the higher apes had been improved or civilised as much as a dog has been in comparison with its parent-form, the wolf or jackal. The Fuegians rank amongst the lowest barbarians; but I was continually struck with surprise how closely the three natives on board H.M.S. "Beagle," who had lived some years in England, and could talk a little English, resembled us in disposition and in most of our mental faculties. If no organic being excepting man had possessed any mental power, or if his powers had been of a wholly different nature from those of the lower animals, then we should never have been able to convince ourselves that our high faculties had been gradually developed. But it can be shewn that there is no fundamental difference of this kind. We must also admit that there is a much wider interval in mental power between one of the lowest fishes, as a lamprey or lancelet, and one of the higher apes, than between an ape and man; yet this interval is filled up by numberless gradations. Nor is the difference slight in moral disposition between a barbarian, such as the man described by the old navigator Byron, who dashed his child on the rocks for dropping a basket of sea-urchins, and a Howard or Clarkson; and in intellect, between a savage who uses hardly any abstract terms, and a Newton or Shakspeare. Differences of this kind between the highest men of the highest races and the lowest savages, are connected by the finest gradations. Therefore it is possible that they might pass and be developed into each other. My object in this chapter is to shew that there is no fundamental difference between man and the higher mammals in their mental faculties. Each division of the subject might have been extended into a separate essay, but must here be treated briefly. As no classification of the mental powers has been universally accepted, I shall arrange my remarks in the order most convenient for my purpose; and will select those facts which have struck me most, with the hope that they may produce some effect on the reader. With respect to animals very low in the scale, I shall give some additional facts under Sexual Selection, shewing that their mental powers are much higher than might have been expected. The variability of the faculties in the individuals of the same species is an important point for us, and some few illustrations will here be given. But it would be superfluous to enter into many details on this head, for I have found on frequent enquiry, that it is the unanimous opinion of all those who have long attended to animals of many kinds, including birds, that the individuals differ greatly in every mental characteristic. In what manner the mental powers were first developed in the lowest organisms, is as hopeless an enquiry as how life itself first originated. These are problems for the distant future, if they are ever to be solved by man. As man possesses the same senses as the lower animals, his fundamental intuitions must be the same. Man has also some few instincts in common, as that of self-preservation, sexual love, the love of the mother for her new-born offspring, the desire possessed by the latter to suck, and so forth. But man, perhaps, has somewhat fewer instincts than those possessed by the animals which come next to him in the series. The orang in the Eastern islands, and the chimpanzee in Africa, build platforms on which they sleep; and, as both species follow the same habit, it might be argued that this was due to instinct, but we cannot feel sure that it is not the result of both animals having similar wants, and possessing similar powers of reasoning. These apes, as we may assume, avoid the many poisonous fruits of the tropics, and man has no such knowledge: but as our domestic animals, when taken to foreign lands, and when first turned out in the spring, often eat poisonous herbs, which they afterwards avoid, we cannot feel sure that the apes do not learn from their own experience or from that of their parents what fruits to select. It is, however, certain, as we shall presently see, that apes have an instinctive dread of serpents, and probably of other dangerous animals. The fewness and the comparative simplicity of the instincts in the higher animals are remarkable in contrast with those of the lower animals. Cuvier maintained that instinct and intelligence stand in an inverse ratio to each other; and some have thought that the intellectual faculties of the higher animals have been gradually developed from their instincts. But Pouchet, in an interesting essay (2. 'L'Instinct chez les Insectes,' 'Revue des Deux Mondes,' Feb. 1870, p. 690.), has shewn that no such inverse ratio really exists. Those insects which possess the most wonderful instincts are certainly the most intelligent. In the vertebrate series, the least intelligent members, namely fishes and amphibians, do not possess complex instincts; and amongst mammals the animal most remarkable for its instincts, namely the beaver, is highly intelligent, as will be admitted by every one who has read Mr. Morgan's excellent work. (3. 'The American Beaver and His Works,' 1868.) Although the first dawnings of intelligence, according to Mr. Herbert Spencer (4. 'The Principles of Psychology,' 2nd edit., 1870, pp. 418-443.), have been developed through the multiplication and co-ordination of reflex actions, and although many of the simpler instincts graduate into reflex actions, and can hardly be distinguished from them, as in the case of young animals sucking, yet the more complex instincts seem to have originated independently of intelligence. I am, however, very far from wishing to deny that instinctive actions may lose their fixed and untaught character, and be replaced by others performed by the aid of the free will. On the other hand, some intelligent actions, after being performed during several generations, become converted into instincts and are inherited, as when birds on oceanic islands learn to avoid man. These actions may then be said to be degraded in character, for they are no longer performed through reason or from experience. But the greater number of the more complex instincts appear to have been gained in a wholly different manner, through the natural selection of variations of simpler instinctive actions. Such variations appear to arise from the same unknown causes acting on the cerebral organisation, which induce slight variations or individual differences in other parts of the body; and these variations, owing to our ignorance, are often said to arise spontaneously. We can, I think, come to no other conclusion with respect to the origin of the more complex instincts, when we reflect on the marvellous instincts of sterile worker-ants and bees, which leave no offspring to inherit the effects of experience and of modified habits. Although, as we learn from the above-mentioned insects and the beaver, a high degree of intelligence is certainly compatible with complex instincts, and although actions, at first learnt voluntarily can soon through habit be performed with the quickness and certainty of a reflex action, yet it is not improbable that there is a certain amount of interference between the development of free intelligence and of instinct,--which latter implies some inherited modification of the brain. Little is known about the functions of the brain, but we can perceive that as the intellectual powers become highly developed, the various parts of the brain must be connected by very intricate channels of the freest intercommunication; and as a consequence each separate part would perhaps tend to be less well fitted to answer to particular sensations or associations in a definite and inherited--that is instinctive--manner. There seems even to exist some relation between a low degree of intelligence and a strong tendency to the formation of fixed, though not inherited habits; for as a sagacious physician remarked to me, persons who are slightly imbecile tend to act in everything by routine or habit; and they are rendered much happier if this is encouraged. I have thought this digression worth giving, because we may easily underrate the mental powers of the higher animals, and especially of man, when we compare their actions founded on the memory of past events, on foresight, reason, and imagination, with exactly similar actions instinctively performed by the lower animals; in this latter case the capacity of performing such actions has been gained, step by step, through the variability of the mental organs and natural selection, without any conscious intelligence on the part of the animal during each successive generation. No doubt, as Mr. Wallace has argued (5. 'Contributions to the Theory of Natural Selection,' 1870, p. 212.), much of the intelligent work done by man is due to imitation and not to reason; but there is this great difference between his actions and many of those performed by the lower animals, namely, that man cannot, on his first trial, make, for instance, a stone hatchet or a canoe, through his power of imitation. He has to learn his work by practice; a beaver, on the other hand, can make its dam or canal, and a bird its nest, as well, or nearly as well, and a spider its wonderful web, quite as well (6. For the evidence on this head, see Mr. J. Traherne Moggridge's most interesting work, 'Harvesting Ants and Trap-Door Spiders,' 1873, pp. 126, 128.), the first time it tries as when old and experienced. To return to our immediate subject: the lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Happiness is never better exhibited than by young animals, such as puppies, kittens, lambs, etc., when playing together, like our own children. Even insects play together, as has been described by that excellent observer, P. Huber (7. 'Recherches sur les Moeurs des Fourmis,' 1810, p. 173.), who saw ants chasing and pretending to bite each other, like so many puppies. The fact that the lower animals are excited by the same emotions as ourselves is so well established, that it will not be necessary to weary the reader by many details. Terror acts in the same manner on them as on us, causing the muscles to tremble, the heart to palpitate, the sphincters to be relaxed, and the hair to stand on end. Suspicion, the offspring of fear, is eminently characteristic of most wild animals. It is, I think, impossible to read the account given by Sir E. Tennent, of the behaviour of the female elephants, used as decoys, without admitting that they intentionally practise deceit, and well know what they are about. Courage and timidity are extremely variable qualities in the individuals of the same species, as is plainly seen in our dogs. Some dogs and horses are ill-tempered, and easily turn sulky; others are good-tempered; and these qualities are certainly inherited. Every one knows how liable animals are to furious rage, and how plainly they shew it. Many, and probably true, anecdotes have been published on the long-delayed and artful revenge of various animals. The accurate Rengger, and Brehm (8. All the following statements, given on the authority of these two naturalists, are taken from Rengger's 'Naturgesch. der Säugethiere von Paraguay,' 1830, s. 41-57, and from Brehm's 'Thierleben,' B. i. s. 10-87.) state that the American and African monkeys which they kept tame, certainly revenged themselves. Sir Andrew Smith, a zoologist whose scrupulous accuracy was known to many persons, told me the following story of which he was himself an eye-witness; at the Cape of Good Hope an officer had often plagued a certain baboon, and the animal, seeing him approaching one Sunday for parade, poured water into a hole and hastily made some thick mud, which he skilfully dashed over the officer as he passed by, to the amusement of many bystanders. For long afterwards the baboon rejoiced and triumphed whenever he saw his victim. The love of a dog for his master is notorious; as an old writer quaintly says (9. Quoted by Dr. Lauder Lindsay, in his 'Physiology of Mind in the Lower Animals,' 'Journal of Mental Science,' April 1871, p. 38.), "A dog is the only thing on this earth that luvs you more than he luvs himself." In the agony of death a dog has been known to caress his master, and every one has heard of the dog suffering under vivisection, who licked the hand of the operator; this man, unless the operation was fully justified by an increase of our knowledge, or unless he had a heart of stone, must have felt remorse to the last hour of his life. As Whewell (10. 'Bridgewater Treatise,' p. 263.) has well asked, "who that reads the touching instances of maternal affection, related so often of the women of all nations, and of the females of all animals, can doubt that the principle of action is the same in the two cases?" We see maternal affection exhibited in the most trifling details; thus Rengger observed an American monkey (a Cebus) carefully driving away the flies which plagued her infant; and Duvaucel saw a Hylobates washing the faces of her young ones in a stream. So intense is the grief of female monkeys for the loss of their young, that it invariably caused the death of certain kinds kept under confinement by Brehm in N. Africa. Orphan monkeys were always adopted and carefully guarded by the other monkeys, both males and females. One female baboon had so capacious a heart that she not only adopted young monkeys of other species, but stole young dogs and cats, which she continually carried about. Her kindness, however, did not go so far as to share her food with her adopted offspring, at which Brehm was surprised, as his monkeys always divided everything quite fairly with their own young ones. An adopted kitten scratched this affectionate baboon, who certainly had a fine intellect, for she was much astonished at being scratched, and immediately examined the kitten's feet, and without more ado bit off the claws. (11. A critic, without any grounds ('Quarterly Review,' July 1871, p. 72), disputes the possibility of this act as described by Brehm, for the sake of discrediting my work. Therefore I tried, and found that I could readily seize with my own teeth the sharp little claws of a kitten nearly five weeks old.) In the Zoological Gardens, I heard from the keeper that an old baboon (C. chacma) had adopted a Rhesus monkey; but when a young drill and mandrill were placed in the cage, she seemed to perceive that these monkeys, though distinct species, were her nearer relatives, for she at once rejected the Rhesus and adopted both of them. The young Rhesus, as I saw, was greatly discontented at being thus rejected, and it would, like a naughty child, annoy and attack the young drill and mandrill whenever it could do so with safety; this conduct exciting great indignation in the old baboon. Monkeys will also, according to Brehm, defend their master when attacked by any one, as well as dogs to whom they are attached, from the attacks of other dogs. But we here trench on the subjects of sympathy and fidelity, to which I shall recur. Some of Brehm's monkeys took much delight in teasing a certain old dog whom they disliked, as well as other animals, in various ingenious ways. Most of the more complex emotions are common to the higher animals and ourselves. Every one has seen how jealous a dog is of his master's affection, if lavished on any other creature; and I have observed the same fact with monkeys. This shews that animals not only love, but have desire to be loved. Animals manifestly feel emulation. They love approbation or praise; and a dog carrying a basket for his master exhibits in a high degree self-complacency or pride. There can, I think, be no doubt that a dog feels shame, as distinct from fear, and something very like modesty when begging too often for food. A great dog scorns the snarling of a little dog, and this may be called magnanimity. Several observers have stated that monkeys certainly dislike being laughed at; and they sometimes invent imaginary offences. In the Zoological Gardens I saw a baboon who always got into a furious rage when his keeper took out a letter or book and read it aloud to him; and his rage was so violent that, as I witnessed on one occasion, he bit his own leg till the blood flowed. Dogs shew what may be fairly called a sense of humour, as distinct from mere play; if a bit of stick or other such object be thrown to one, he will often carry it away for a short distance; and then squatting down with it on the ground close before him, will wait until his master comes quite close to take it away. The dog will then seize it and rush away in triumph, repeating the same manoeuvre, and evidently enjoying the practical joke. We will now turn to the more intellectual emotions and faculties, which are very important, as forming the basis for the development of the higher mental powers. Animals manifestly enjoy excitement, and suffer from ennui, as may be seen with dogs, and, according to Rengger, with monkeys. All animals feel WONDER, and many exhibit CURIOSITY. They sometimes suffer from this latter quality, as when the hunter plays antics and thus attracts them; I have witnessed this with deer, and so it is with the wary chamois, and with some kinds of wild-ducks. Brehm gives a curious account of the instinctive dread, which his monkeys exhibited, for snakes; but their curiosity was so great that they could not desist from occasionally satiating their horror in a most human fashion, by lifting up the lid of the box in which the snakes were kept. I was so much surprised at his account, that I took a stuffed and coiled-up snake into the monkey-house at the Zoological Gardens, and the excitement thus caused was one of the most curious spectacles which I ever beheld. Three species of Cercopithecus were the most alarmed; they dashed about their cages, and uttered sharp signal cries of danger, which were understood by the other monkeys. A few young monkeys and one old Anubis baboon alone took no notice of the snake. I then placed the stuffed specimen on the ground in one of the larger compartments. After a time all the monkeys collected round it in a large circle, and staring intently, presented a most ludicrous appearance. They became extremely nervous; so that when a wooden ball, with which they were familiar as a plaything, was accidentally moved in the straw, under which it was partly hidden, they all instantly started away. These monkeys behaved very differently when a dead fish, a mouse (12. I have given a short account of their behaviour on this occasion in my 'Expression of the Emotions in Man and Animals,' p. 43.), a living turtle, and other new objects were placed in their cages; for though at first frightened, they soon approached, handled and examined them. I then placed a live snake in a paper bag, with the mouth loosely closed, in one of the larger compartments. One of the monkeys immediately approached, cautiously opened the bag a little, peeped in, and instantly dashed away. Then I witnessed what Brehm has described, for monkey after monkey, with head raised high and turned on one side, could not resist taking a momentary peep into the upright bag, at the dreadful object lying quietly at the bottom. It would almost appear as if monkeys had some notion of zoological affinities, for those kept by Brehm exhibited a strange, though mistaken, instinctive dread of innocent lizards and frogs. An orang, also, has been known to be much alarmed at the first sight of a turtle. (13. W.C.L. Martin, 'Natural History of Mammalia,' 1841, p. 405.) The principle of IMITATION is strong in man, and especially, as I have myself observed, with savages. In certain morbid states of the brain this tendency is exaggerated to an extraordinary degree: some hemiplegic patients and others, at the commencement of inflammatory softening of the brain, unconsciously imitate every word which is uttered, whether in their own or in a foreign language, and every gesture or action which is performed near them. (14. Dr. Bateman, 'On Aphasia,' 1870, p. 110.) Desor (15. Quoted by Vogt, 'Mémoire sur les Microcephales,' 1867, p. 168.) has remarked that no animal voluntarily imitates an action performed by man, until in the ascending scale we come to monkeys, which are well known to be ridiculous mockers. Animals, however, sometimes imitate each other's actions: thus two species of wolves, which had been reared by dogs, learned to bark, as does sometimes the jackal (16. The 'Variation of Animals and Plants under Domestication,' vol. i. p. 27.), but whether this can be called voluntary imitation is another question. Birds imitate the songs of their parents, and sometimes of other birds; and parrots are notorious imitators of any sound which they often hear. Dureau de la Malle gives an account (17. 'Annales des Sciences Nat.' (1st Series), tom. xxii. p. 397.) of a dog reared by a cat, who learnt to imitate the well-known action of a cat licking her paws, and thus washing her ears and face; this was also witnessed by the celebrated naturalist Audouin. I have received several confirmatory accounts; in one of these, a dog had not been suckled by a cat, but had been brought up with one, together with kittens, and had thus acquired the above habit, which he ever afterwards practised during his life of thirteen years. Dureau de la Malle's dog likewise learnt from the kittens to play with a ball by rolling it about with his fore paws, and springing on it. A correspondent assures me that a cat in his house used to put her paws into jugs of milk having too narrow a mouth for her head. A kitten of this cat soon learned the same trick, and practised it ever afterwards, whenever there was an opportunity. The parents of many animals, trusting to the principle of imitation in their young, and more especially to their instinctive or inherited tendencies, may be said to educate them. We see this when a cat brings a live mouse to her kittens; and Dureau de la Malle has given a curious account (in the paper above quoted) of his observations on hawks which taught their young dexterity, as well as judgment of distances, by first dropping through the air dead mice and sparrows, which the young generally failed to catch, and then bringing them live birds and letting them loose. Hardly any faculty is more important for the intellectual progress of man than ATTENTION. Animals clearly manifest this power, as when a cat watches by a hole and prepares to spring on its prey. Wild animals sometimes become so absorbed when thus engaged, that they may be easily approached. Mr. Bartlett has given me a curious proof how variable this faculty is in monkeys. A man who trains monkeys to act in plays, used to purchase common kinds from the Zoological Society at the price of five pounds for each; but he offered to give double the price, if he might keep three or four of them for a few days, in order to select one. When asked how he could possibly learn so soon, whether a particular monkey would turn out a good actor, he answered that it all depended on their power of attention. If when he was talking and explaining anything to a monkey, its attention was easily distracted, as by a fly on the wall or other trifling object, the case was hopeless. If he tried by punishment to make an inattentive monkey act, it turned sulky. On the other hand, a monkey which carefully attended to him could always be trained. It is almost superfluous to state that animals have excellent MEMORIES for persons and places. A baboon at the Cape of Good Hope, as I have been informed by Sir Andrew Smith, recognised him with joy after an absence of nine months. I had a dog who was savage and averse to all strangers, and I purposely tried his memory after an absence of five years and two days. I went near the stable where he lived, and shouted to him in my old manner; he shewed no joy, but instantly followed me out walking, and obeyed me, exactly as if I had parted with him only half an hour before. A train of old associations, dormant during five years, had thus been instantaneously awakened in his mind. Even ants, as P. Huber (18. 'Les Moeurs des Fourmis,' 1810, p. 150.) has clearly shewn, recognised their fellow-ants belonging to the same community after a separation of four months. Animals can certainly by some means judge of the intervals of time between recurrent events. The IMAGINATION is one of the highest prerogatives of man. By this faculty he unites former images and ideas, independently of the will, and thus creates brilliant and novel results. A poet, as Jean Paul Richter remarks (19. Quoted in Dr. Maudsley's 'Physiology and Pathology of Mind,' 1868, pp. 19, 220.), "who must reflect whether he shall make a character say yes or no--to the devil with him; he is only a stupid corpse." Dreaming gives us the best notion of this power; as Jean Paul again says, "The dream is an involuntary art of poetry." The value of the products of our imagination depends of course on the number, accuracy, and clearness of our impressions, on our judgment and taste in selecting or rejecting the involuntary combinations, and to a certain extent on our power of voluntarily combining them. As dogs, cats, horses, and probably all the higher animals, even birds (20. Dr. Jerdon, 'Birds of India,' vol. i. 1862, p. xxi. Houzeau says that his parokeets and canary-birds dreamt: 'Etudes sur les Facultes Mentales des Animaux,' tom. ii. p. 136.) have vivid dreams, and this is shewn by their movements and the sounds uttered, we must admit that they possess some power of imagination. There must be something special, which causes dogs to howl in the night, and especially during moonlight, in that remarkable and melancholy manner called baying. All dogs do not do so; and, according to Houzeau (21. ibid. 1872, tom. ii. p. 181.), they do not then look at the moon, but at some fixed point near the horizon. Houzeau thinks that their imaginations are disturbed by the vague outlines of the surrounding objects, and conjure up before them fantastic images: if this be so, their feelings may almost be called superstitious. Of all the faculties of the human mind, it will, I presume, be admitted that REASON stands at the summit. Only a few persons now dispute that animals possess some power of reasoning. Animals may constantly be seen to pause, deliberate, and resolve. It is a significant fact, that the more the habits of any particular animal are studied by a naturalist, the more he attributes to reason and the less to unlearnt instincts. (22. Mr. L.H. Morgan's work on 'The American Beaver,' 1868, offers a good illustration of this remark. I cannot help thinking, however, that he goes too far in underrating the power of instinct.) In future chapters we shall see that some animals extremely low in the scale apparently display a certain amount of reason. No doubt it is often difficult to distinguish between the power of reason and that of instinct. For instance, Dr. Hayes, in his work on 'The Open Polar Sea,' repeatedly remarks that his dogs, instead of continuing to draw the sledges in a compact body, diverged and separated when they came to thin ice, so that their weight might be more evenly distributed. This was often the first warning which the travellers received that the ice was becoming thin and dangerous. Now, did the dogs act thus from the experience of each individual, or from the example of the older and wiser dogs, or from an inherited habit, that is from instinct? This instinct, may possibly have arisen since the time, long ago, when dogs were first employed by the natives in drawing their sledges; or the Arctic wolves, the parent-stock of the Esquimaux dog, may have acquired an instinct impelling them not to attack their prey in a close pack, when on thin ice. We can only judge by the circumstances under which actions are performed, whether they are due to instinct, or to reason, or to the mere association of ideas: this latter principle, however, is intimately connected with reason. A curious case has been given by Prof. Mobius (23. 'Die Bewegungen der Thiere,' etc., 1873, p. 11.), of a pike, separated by a plate of glass from an adjoining aquarium stocked with fish, and who often dashed himself with such violence against the glass in trying to catch the other fishes, that he was sometimes completely stunned. The pike went on thus for three months, but at last learnt caution, and ceased to do so. The plate of glass was then removed, but the pike would not attack these particular fishes, though he would devour others which were afterwards introduced; so strongly was the idea of a violent shock associated in his feeble mind with the attempt on his former neighbours. If a savage, who had never seen a large plate-glass window, were to dash himself even once against it, he would for a long time afterwards associate a shock with a window-frame; but very differently from the pike, he would probably reflect on the nature of the impediment, and be cautious under analogous circumstances. Now with monkeys, as we shall presently see, a painful or merely a disagreeable impression, from an action once performed, is sometimes sufficient to prevent the animal from repeating it. If we attribute this difference between the monkey and the pike solely to the association of ideas being so much stronger and more persistent in the one than the other, though the pike often received much the more severe injury, can we maintain in the case of man that a similar difference implies the possession of a fundamentally different mind? Houzeau relates (24. '�tudes sur les Facultés Mentales des Animaux,' 1872, tom. ii. p. 265.) that, whilst crossing a wide and arid plain in Texas, his two dogs suffered greatly from thirst, and that between thirty and forty times they rushed down the hollows to search for water. These hollows were not valleys, and there were no trees in them, or any other difference in the vegetation, and as they were absolutely dry there could have been no smell of damp earth. The dogs behaved as if they knew that a dip in the ground offered them the best chance of finding water, and Houzeau has often witnessed the same behaviour in other animals. I have seen, as I daresay have others, that when a small object is thrown on the ground beyond the reach of one of the elephants in the Zoological Gardens, he blows through his trunk on the ground beyond the object, so that the current reflected on all sides may drive the object within his reach. Again a well-known ethnologist, Mr. Westropp, informs me that he observed in Vienna a bear deliberately making with his paw a current in some water, which was close to the bars of his cage, so as to draw a piece of floating bread within his reach. These actions of the elephant and bear can hardly be attributed to instinct or inherited habit, as they would be of little use to an animal in a state of nature. Now, what is the difference between such actions, when performed by an uncultivated man, and by one of the higher animals? The savage and the dog have often found water at a low level, and the coincidence under such circumstances has become associated in their minds. A cultivated man would perhaps make some general proposition on the subject; but from all that we know of savages it is extremely doubtful whether they would do so, and a dog certainly would not. But a savage, as well as a dog, would search in the same way, though frequently disappointed; and in both it seems to be equally an act of reason, whether or not any general proposition on the subject is consciously placed before the mind. (25. Prof. Huxley has analysed with admirable clearness the mental steps by which a man, as well as a dog, arrives at a conclusion in a case analogous to that given in my text. See his article, 'Mr. Darwin's Critics,' in the 'Contemporary Review,' Nov. 1871, p. 462, and in his 'Critiques and Essays,' 1873, p. 279.) The same would apply to the elephant and the bear making currents in the air or water. The savage would certainly neither know nor care by what law the desired movements were effected; yet his act would be guided by a rude process of reasoning, as surely as would a philosopher in his longest chain of deductions. There would no doubt be this difference between him and one of the higher animals, that he would take notice of much slighter circumstances and conditions, and would observe any connection between them after much less experience, and this would be of paramount importance. I kept a daily record of the actions of one of my infants, and when he was about eleven months old, and before he could speak a single word, I was continually struck with the greater quickness, with which all sorts of objects and sounds were associated together in his mind, compared with that of the most intelligent dogs I ever knew. But the higher animals differ in exactly the same way in this power of association from those low in the scale, such as the pike, as well as in that of drawing inferences and of observation. The promptings of reason, after very short experience, are well shewn by the following actions of American monkeys, which stand low in their order. Rengger, a most careful observer, states that when he first gave eggs to his monkeys in Paraguay, they smashed them, and thus lost much of their contents; afterwards they gently hit one end against some hard body, and picked off the bits of shell with their fingers. After cutting themselves only ONCE with any sharp tool, they would not touch it again, or would handle it with the greatest caution. Lumps of sugar were often given them wrapped up in paper; and Rengger sometimes put a live wasp in the paper, so that in hastily unfolding it they got stung; after this had ONCE happened, they always first held the packet to their ears to detect any movement within. (26. Mr. Belt, in his most interesting work, 'The Naturalist in Nicaragua,' 1874, (p. 119), likewise describes various actions of a tamed Cebus, which, I think, clearly shew that this animal possessed some reasoning power.) The following cases relate to dogs. Mr. Colquhoun (27. 'The Moor and the Loch,' p. 45. Col. Hutchinson on 'Dog Breaking,' 1850, p. 46.) winged two wild-ducks, which fell on the further side of a stream; his retriever tried to bring over both at once, but could not succeed; she then, though never before known to ruffle a feather, deliberately killed one, brought over the other, and returned for the dead bird. Col. Hutchinson relates that two partridges were shot at once, one being killed, the other wounded; the latter ran away, and was caught by the retriever, who on her return came across the dead bird; "she stopped, evidently greatly puzzled, and after one or two trials, finding she could not take it up without permitting the escape of the winged bird, she considered a moment, then deliberately murdered it by giving it a severe crunch, and afterwards brought away both together. This was the only known instance of her ever having wilfully injured any game." Here we have reason though not quite perfect, for the retriever might have brought the wounded bird first and then returned for the dead one, as in the case of the two wild-ducks. I give the above cases, as resting on the evidence of two independent witnesses, and because in both instances the retrievers, after deliberation, broke through a habit which is inherited by them (that of not killing the game retrieved), and because they shew how strong their reasoning faculty must have been to overcome a fixed habit. I will conclude by quoting a remark by the illustrious Humboldt. (28. 'Personal Narrative,' Eng. translat., vol. iii. p. 106.) "The muleteers in S. America say, 'I will not give you the mule whose step is easiest, but la mas racional,--the one that reasons best'"; and; as, he adds, "this popular expression, dictated by long experience, combats the system of animated machines, better perhaps than all the arguments of speculative philosophy." Nevertheless some writers even yet deny that the higher animals possess a trace of reason; and they endeavour to explain away, by what appears to be mere verbiage, (29. I am glad to find that so acute a reasoner as Mr. Leslie Stephen ('Darwinism and Divinity, Essays on Free Thinking,' 1873, p. 80), in speaking of the supposed impassable barrier between the minds of man and the lower animals, says, "The distinctions, indeed, which have been drawn, seem to us to rest upon no better foundation than a great many other metaphysical distinctions; that is, the assumption that because you can give two things different names, they must therefore have different natures. It is difficult to understand how anybody who has ever kept a dog, or seen an elephant, can have any doubt as to an animal's power of performing the essential processes of reasoning.") all such facts as those above given. It has, I think, now been shewn that man and the higher animals, especially the Primates, have some few instincts in common. All have the same senses, intuitions, and sensations,--similar passions, affections, and emotions, even the more complex ones, such as jealousy, suspicion, emulation, gratitude, and magnanimity; they practise deceit and are revengeful; they are sometimes susceptible to ridicule, and even have a sense of humour; they feel wonder and curiosity; they possess the same faculties of imitation, attention, deliberation, choice, memory, imagination, the association of ideas, and reason, though in very different degrees. The individuals of the same species graduate in intellect from absolute imbecility to high excellence. They are also liable to insanity, though far less often than in the case of man. (30. See 'Madness in Animals,' by Dr. W. Lauder Lindsay, in 'Journal of Mental Science,' July 1871.) Nevertheless, many authors have insisted that man is divided by an insuperable barrier from all the lower animals in his mental faculties. I formerly made a collection of above a score of such aphorisms, but they are almost worthless, as their wide difference and number prove the difficulty, if not the impossibility, of the attempt. It has been asserted that man alone is capable of progressive improvement; that he alone makes use of tools or fire, domesticates other animals, or possesses property; that no animal has the power of abstraction, or of forming general concepts, is self-conscious and comprehends itself; that no animal employs language; that man alone has a sense of beauty, is liable to caprice, has the feeling of gratitude, mystery, etc.; believes in God, or is endowed with a conscience. I will hazard a few remarks on the more important and interesting of these points. Archbishop Sumner formerly maintained (31. Quoted by Sir C. Lyell, 'Antiquity of Man,' p. 497.) that man alone is capable of progressive improvement. That he is capable of incomparably greater and more rapid improvement than is any other animal, admits of no dispute; and this is mainly due to his power of speaking and handing down his acquired knowledge. With animals, looking first to the individual, every one who has had any experience in setting traps, knows that young animals can be caught much more easily than old ones; and they can be much more easily approached by an enemy. Even with respect to old animals, it is impossible to catch many in the same place and in the same kind of trap, or to destroy them by the same kind of poison; yet it is improbable that all should have partaken of the poison, and impossible that all should have been caught in a trap. They must learn caution by seeing their brethren caught or poisoned. In North America, where the fur-bearing animals have long been pursued, they exhibit, according to the unanimous testimony of all observers, an almost incredible amount of sagacity, caution and cunning; but trapping has been there so long carried on, that inheritance may possibly have come into play. I have received several accounts that when telegraphs are first set up in any district, many birds kill themselves by flying against the wires, but that in the course of a very few years they learn to avoid this danger, by seeing, as it would appear, their comrades killed. (32. For additional evidence, with details, see M. Houzeau, '�tudes sur les Facultés Mentales des Animaux,' tom. ii. 1872, p. 147.) If we look to successive generations, or to the race, there is no doubt that birds and other animals gradually both acquire and lose caution in relation to man or other enemies (33. See, with respect to birds on oceanic islands, my 'Journal of Researches during the Voyage of the "Beagle,"' 1845, p. 398. 'Origin of Species,' 5th ed. p. 260.); and this caution is certainly in chief part an inherited habit or instinct, but in part the result of individual experience. A good observer, Leroy (34. 'Lettres Phil. sur l'Intelligence des Animaux,' nouvelle edit., 1802, p. 86.), states, that in districts where foxes are much hunted, the young, on first leaving their burrows, are incontestably much more wary than the old ones in districts where they are not much disturbed. Our domestic dogs are descended from wolves and jackals (35. See the evidence on this head in chap. i. vol. i., 'On the Variation of Animals and Plants under Domestication.'), and though they may not have gained in cunning, and may have lost in wariness and suspicion, yet they have progressed in certain moral qualities, such as in affection, trust-worthiness, temper, and probably in general intelligence. The common rat has conquered and beaten several other species throughout Europe, in parts of North America, New Zealand, and recently in Formosa, as well as on the mainland of China. Mr. Swinhoe (36. 'Proceedings Zoological Society,' 1864, p. 186.), who describes these two latter cases, attributes the victory of the common rat over the large Mus coninga to its superior cunning; and this latter quality may probably be attributed to the habitual exercise of all its faculties in avoiding extirpation by man, as well as to nearly all the less cunning or weak-minded rats having been continuously destroyed by him. It is, however, possible that the success of the common rat may be due to its having possessed greater cunning than its fellow-species, before it became associated with man. To maintain, independently of any direct evidence, that no animal during the course of ages has progressed in intellect or other mental faculties, is to beg the question of the evolution of species. We have seen that, according to Lartet, existing mammals belonging to several orders have larger brains than their ancient tertiary prototypes. It has often been said that no animal uses any tool; but the chimpanzee in a state of nature cracks a native fruit, somewhat like a walnut, with a stone. (37. Savage and Wyman in 'Boston Journal of Natural History,' vol. iv. 1843-44, p. 383.) Rengger (38. 'Säugethiere von Paraguay,' 1830, s. 51-56.) easily taught an American monkey thus to break open hard palm-nuts; and afterwards of its own accord, it used stones to open other kinds of nuts, as well as boxes. It thus also removed the soft rind of fruit that had a disagreeable flavour. Another monkey was taught to open the lid of a large box with a stick, and afterwards it used the stick as a lever to move heavy bodies; and I have myself seen a young orang put a stick into a crevice, slip his hand to the other end, and use it in the proper manner as a lever. The tamed elephants in India are well known to break off branches of trees and use them to drive away the flies; and this same act has been observed in an elephant in a state of nature. (39. The Indian Field, March 4, 1871.) I have seen a young orang, when she thought she was going to be whipped, cover and protect herself with a blanket or straw. In these several cases stones and sticks were employed as implements; but they are likewise used as weapons. Brehm (40. 'Thierleben,' B. i. s. 79, 82.) states, on the authority of the well-known traveller Schimper, that in Abyssinia when the baboons belonging to one species (C. gelada) descend in troops from the mountains to plunder the fields, they sometimes encounter troops of another species (C. hamadryas), and then a fight ensues. The Geladas roll down great stones, which the Hamadryas try to avoid, and then both species, making a great uproar, rush furiously against each other. Brehm, when accompanying the Duke of Coburg-Gotha, aided in an attack with fire-arms on a troop of baboons in the pass of Mensa in Abyssinia. The baboons in return rolled so many stones down the mountain, some as large as a man's head, that the attackers had to beat a hasty retreat; and the pass was actually closed for a time against the caravan. It deserves notice that these baboons thus acted in concert. Mr. Wallace (41. 'The Malay Archipelago,' vol. i. 1869, p. 87.) on three occasions saw female orangs, accompanied by their young, "breaking off branches and the great spiny fruit of the Durian tree, with every appearance of rage; causing such a shower of missiles as effectually kept us from approaching too near the tree." As I have repeatedly seen, a chimpanzee will throw any object at hand at a person who offends him; and the before-mentioned baboon at the Cape of Good Hope prepared mud for the purpose. In the Zoological Gardens, a monkey, which had weak teeth, used to break open nuts with a stone; and I was assured by the keepers that after using the stone, he hid it in the straw, and would not let any other monkey touch it. Here, then, we have the idea of property; but this idea is common to every dog with a bone, and to most or all birds with their nests. The Duke of Argyll (42. 'Primeval Man,' 1869, pp. 145, 147.) remarks, that the fashioning of an implement for a special purpose is absolutely peculiar to man; and he considers that this forms an immeasurable gulf between him and the brutes. This is no doubt a very important distinction; but there appears to me much truth in Sir J. Lubbock's suggestion (43. 'Prehistoric Times,' 1865, p. 473, etc.), that when primeval man first used flint-stones for any purpose, he would have accidentally splintered them, and would then have used the sharp fragments. From this step it would be a small one to break the flints on purpose, and not a very wide step to fashion them rudely. This latter advance, however, may have taken long ages, if we may judge by the immense interval of time which elapsed before the men of the neolithic period took to grinding and polishing their stone tools. In breaking the flints, as Sir J. Lubbock likewise remarks, sparks would have been emitted, and in grinding them heat would have been evolved: thus the two usual methods of "obtaining fire may have originated." The nature of fire would have been known in the many volcanic regions where lava occasionally flows through forests. The anthropomorphous apes, guided probably by instinct, build for themselves temporary platforms; but as many instincts are largely controlled by reason, the simpler ones, such as this of building a platform, might readily pass into a voluntary and conscious act. The orang is known to cover itself at night with the leaves of the Pandanus; and Brehm states that one of his baboons used to protect itself from the heat of the sun by throwing a straw-mat over its head. In these several habits, we probably see the first steps towards some of the simpler arts, such as rude architecture and dress, as they arose amongst the early progenitors of man. ABSTRACTION, GENERAL CONCEPTIONS, SELF-CONSCIOUSNESS, MENTAL INDIVIDUALITY. It would be very difficult for any one with even much more knowledge than I possess, to determine how far animals exhibit any traces of these high mental powers. This difficulty arises from the impossibility of judging what passes through the mind of an animal; and again, the fact that writers differ to a great extent in the meaning which they attribute to the above terms, causes a further difficulty. If one may judge from various articles which have been published lately, the greatest stress seems to be laid on the supposed entire absence in animals of the power of abstraction, or of forming general concepts. But when a dog sees another dog at a distance, it is often clear that he perceives that it is a dog in the abstract; for when he gets nearer his whole manner suddenly changes, if the other dog be a friend. A recent writer remarks, that in all such cases it is a pure assumption to assert that the mental act is not essentially of the same nature in the animal as in man. If either refers what he perceives with his senses to a mental concept, then so do both. (44. Mr. Hookham, in a letter to Prof. Max Muller, in the 'Birmingham News,' May 1873.) When I say to my terrier, in an eager voice (and I have made the trial many times), "Hi, hi, where is it?" she at once takes it as a sign that something is to be hunted, and generally first looks quickly all around, and then rushes into the nearest thicket, to scent for any game, but finding nothing, she looks up into any neighbouring tree for a squirrel. Now do not these actions clearly shew that she had in her mind a general idea or concept that some animal is to be discovered and hunted? It may be freely admitted that no animal is self-conscious, if by this term it is implied, that he reflects on such points, as whence he comes or whither he will go, or what is life and death, and so forth. But how can we feel sure that an old dog with an excellent memory and some power of imagination, as shewn by his dreams, never reflects on his past pleasures or pains in the chase? And this would be a form of self-consciousness. On the other hand, as Buchner (45. 'Conférences sur la Théorie Darwinienne,' French translat. 1869, p. 132.) has remarked, how little can the hard-worked wife of a degraded Australian savage, who uses very few abstract words, and cannot count above four, exert her self-consciousness, or reflect on the nature of her own existence. It is generally admitted, that the higher animals possess memory, attention, association, and even some imagination and reason. If these powers, which differ much in different animals, are capable of improvement, there seems no great improbability in more complex faculties, such as the higher forms of abstraction, and self-consciousness, etc., having been evolved through the development and combination of the simpler ones. It has been urged against the views here maintained that it is impossible to say at what point in the ascending scale animals become capable of abstraction, etc.; but who can say at what age this occurs in our young children? We see at least that such powers are developed in children by imperceptible degrees. That animals retain their mental individuality is unquestionable. When my voice awakened a train of old associations in the mind of the before-mentioned dog, he must have retained his mental individuality, although every atom of his brain had probably undergone change more than once during the interval of five years. This dog might have brought forward the argument lately advanced to crush all evolutionists, and said, "I abide amid all mental moods and all material changes...The teaching that atoms leave their impressions as legacies to other atoms falling into the places they have vacated is contradictory of the utterance of consciousness, and is therefore false; but it is the teaching necessitated by evolutionism, consequently the hypothesis is a false one." (46. The Rev. Dr. J. M'Cann, 'Anti-Darwinism,' 1869, p. 13.) LANGUAGE. This faculty has justly been considered as one of the chief distinctions between man and the lower animals. But man, as a highly competent judge, Archbishop Whately remarks, "is not the only animal that can make use of language to express what is passing in his mind, and can understand, more or less, what is so expressed by another." (47. Quoted in 'Anthropological Review,' 1864, p. 158.) In Paraguay the Cebus azarae when excited utters at least six distinct sounds, which excite in other monkeys similar emotions. (48. Rengger, ibid. s. 45.) The movements of the features and gestures of monkeys are understood by us, and they partly understand ours, as Rengger and others declare. It is a more remarkable fact that the dog, since being domesticated, has learnt to bark (49. See my 'Variation of Animals and Plants under Domestication,' vol. i. p. 27.) in at least four or five distinct tones. Although barking is a new art, no doubt the wild parent-species of the dog expressed their feelings by cries of various kinds. With the domesticated dog we have the bark of eagerness, as in the chase; that of anger, as well as growling; the yelp or howl of despair, as when shut up; the baying at night; the bark of joy, as when starting on a walk with his master; and the very distinct one of demand or supplication, as when wishing for a door or window to be opened. According to Houzeau, who paid particular attention to the subject, the domestic fowl utters at least a dozen significant sounds. (50. 'Facultés Mentales des Animaux,' tom. ii. 1872, p. 346-349.) The habitual use of articulate language is, however, peculiar to man; but he uses, in common with the lower animals, inarticulate cries to express his meaning, aided by gestures and the movements of the muscles of the face. (51. See a discussion on this subject in Mr. E.B. Tylor's very interesting work, 'Researches into the Early History of Mankind,' 1865, chaps. ii. to iv.) This especially holds good with the more simple and vivid feelings, which are but little connected with our higher intelligence. Our cries of pain, fear, surprise, anger, together with their appropriate actions, and the murmur of a mother to her beloved child are more expressive than any words. That which distinguishes man from the lower animals is not the understanding of articulate sounds, for, as every one knows, dogs understand many words and sentences. In this respect they are at the same stage of development as infants, between the ages of ten and twelve months, who understand many words and short sentences, but cannot yet utter a single word. It is not the mere articulation which is our distinguishing character, for parrots and other birds possess this power. Nor is it the mere capacity of connecting definite sounds with definite ideas; for it is certain that some parrots, which have been taught to speak, connect unerringly words with things, and persons with events. (52. I have received several detailed accounts to this effect. Admiral Sir B.J. Sulivan, whom I know to be a careful observer, assures me that an African parrot, long kept in his father's house, invariably called certain persons of the household, as well as visitors, by their names. He said "good morning" to every one at breakfast, and "good night" to each as they left the room at night, and never reversed these salutations. To Sir B.J. Sulivan's father, he used to add to the " good morning" a short sentence, which was never once repeated after his father's death. He scolded violently a strange dog which came into the room through the open window; and he scolded another parrot (saying "you naughty polly") which had got out of its cage, and was eating apples on the kitchen table. See also, to the same effect, Houzeau on parrots, 'Facultés Mentales,' tom. ii. p. 309. Dr. A. Moschkau informs me that he knew a starling which never made a mistake in saying in German "good morning" to persons arriving, and "good bye, old fellow," to those departing. I could add several other such cases.) The lower animals differ from man solely in his almost infinitely larger power of associating together the most diversified sounds and ideas; and this obviously depends on the high development of his mental powers. As Horne Tooke, one of the founders of the noble science of philology, observes, language is an art, like brewing or baking; but writing would have been a better simile. It certainly is not a true instinct, for every language has to be learnt. It differs, however, widely from all ordinary arts, for man has an instinctive tendency to speak, as we see in the babble of our young children; whilst no child has an instinctive tendency to brew, bake, or write. Moreover, no philologist now supposes that any language has been deliberately invented; it has been slowly and unconsciously developed by many steps. (53. See some good remarks on this head by Prof. Whitney, in his 'Oriental and Linguistic Studies,' 1873, p. 354. He observes that the desire of communication between man is the living force, which, in the development of language, "works both consciously and unconsciously; consciously as regards the immediate end to be attained; unconsciously as regards the further consequences of the act.") The sounds uttered by birds offer in several respects the nearest analogy to language, for all the members of the same species utter the same instinctive cries expressive of their emotions; and all the kinds which sing, exert their power instinctively; but the actual song, and even the call-notes, are learnt from their parents or foster-parents. These sounds, as Daines Barrington (54. Hon. Daines Barrington in 'Philosoph. Transactions,' 1773, p. 262. See also Dureau de la Malle, in 'Ann. des. Sc. Nat.' 3rd series, Zoolog., tom. x. p. 119.) has proved, "are no more innate than language is in man." The first attempts to sing "may be compared to the imperfect endeavour in a child to babble." The young males continue practising, or as the bird-catchers say, "recording," for ten or eleven months. Their first essays shew hardly a rudiment of the future song; but as they grow older we can perceive what they are aiming at; and at last they are said "to sing their song round." Nestlings which have learnt the song of a distinct species, as with the canary-birds educated in the Tyrol, teach and transmit their new song to their offspring. The slight natural differences of song in the same species inhabiting different districts may be appositely compared, as Barrington remarks, "to provincial dialects"; and the songs of allied, though distinct species may be compared with the languages of distinct races of man. I have given the foregoing details to shew that an instinctive tendency to acquire an art is not peculiar to man. With respect to the origin of articulate language, after having read on the one side the highly interesting works of Mr. Hensleigh Wedgwood, the Rev. F. Farrar, and Prof. Schleicher (55. 'On the Origin of Language,' by H. Wedgwood, 1866. 'Chapters on Language,' by the Rev. F.W. Farrar, 1865. These works are most interesting. See also 'De la Phys. et de Parole,' par Albert Lemoine, 1865, p. 190. The work on this subject, by the late Prof. Aug. Schleicher, has been translated by Dr. Bikkers into English, under the title of 'Darwinism tested by the Science of Language,' 1869.), and the celebrated lectures of Prof. Max Muller on the other side, I cannot doubt that language owes its origin to the imitation and modification of various natural sounds, the voices of other animals, and man's own instinctive cries, aided by signs and gestures. When we treat of sexual selection we shall see that primeval man, or rather some early progenitor of man, probably first used his voice in producing true musical cadences, that is in singing, as do some of the gibbon-apes at the present day; and we may conclude from a widely-spread analogy, that this power would have been especially exerted during the courtship of the sexes,--would have expressed various emotions, such as love, jealousy, triumph,--and would have served as a challenge to rivals. It is, therefore, probable that the imitation of musical cries by articulate sounds may have given rise to words expressive of various complex emotions. The strong tendency in our nearest allies, the monkeys, in microcephalous idiots (56. Vogt, 'Mémoire sur les Microcephales,' 1867, p. 169. With respect to savages, I have given some facts in my 'Journal of Researches,' etc., 1845, p. 206.), and in the barbarous races of mankind, to imitate whatever they hear deserves notice, as bearing on the subject of imitation. Since monkeys certainly understand much that is said to them by man, and when wild, utter signal-cries of danger to their fellows (57. See clear evidence on this head in the two works so often quoted, by Brehm and Rengger.); and since fowls give distinct warnings for danger on the ground, or in the sky from hawks (both, as well as a third cry, intelligible to dogs) (58. Houzeau gives a very curious account of his observations on this subject in his 'Facultés Mentales des Animaux,' tom. ii. p. 348.), may not some unusually wise ape-like animal have imitated the growl of a beast of prey, and thus told his fellow-monkeys the nature of the expected danger? This would have been a first step in the formation of a language. As the voice was used more and more, the vocal organs would have been strengthened and perfected through the principle of the inherited effects of use; and this would have reacted on the power of speech. But the relation between the continued use of language and the development of the brain, has no doubt been far more important. The mental powers in some early progenitor of man must have been more highly developed than in any existing ape, before even the most imperfect form of speech could have come into use; but we may confidently believe that the continued use and advancement of this power would have reacted on the mind itself, by enabling and encouraging it to carry on long trains of thought. A complex train of thought can no more be carried on without the aid of words, whether spoken or silent, than a long calculation without the use of figures or algebra. It appears, also, that even an ordinary train of thought almost requires, or is greatly facilitated by some form of language, for the dumb, deaf, and blind girl, Laura Bridgman, was observed to use her fingers whilst dreaming. (59. See remarks on this head by Dr. Maudsley, 'The Physiology and Pathology of Mind,' 2nd ed., 1868, p. 199.) Nevertheless, a long succession of vivid and connected ideas may pass through the mind without the aid of any form of language, as we may infer from the movements of dogs during their dreams. We have, also, seen that animals are able to reason to a certain extent, manifestly without the aid of language. The intimate connection between the brain, as it is now developed in us, and the faculty of speech, is well shewn by those curious cases of brain-disease in which speech is specially affected, as when the power to remember substantives is lost, whilst other words can be correctly used, or where substantives of a certain class, or all except the initial letters of substantives and proper names are forgotten. (60. Many curious cases have been recorded. See, for instance, Dr. Bateman 'On Aphasia,' 1870, pp. 27, 31, 53, 100, etc. Also, 'Inquiries Concerning the Intellectual Powers,' by Dr. Abercrombie, 1838, p. 150.) There is no more improbability in the continued use of the mental and vocal organs leading to inherited changes in their structure and functions, than in the case of hand-writing, which depends partly on the form of the hand and partly on the disposition of the mind; and handwriting is certainly inherited. (61. 'The Variation of Animals and Plants under Domestication,' vol. ii. p. 6.') Several writers, more especially Prof. Max Muller (62. Lectures on 'Mr. Darwin's Philosophy of Language,' 1873.), have lately insisted that the use of language implies the power of forming general concepts; and that as no animals are supposed to possess this power, an impassable barrier is formed between them and man. (63. The judgment of a distinguished philologist, such as Prof. Whitney, will have far more weight on this point than anything that I can say. He remarks ('Oriental and Linguistic Studies,' 1873, p. 297), in speaking of Bleek's views: "Because on the grand scale language is the necessary auxiliary of thought, indispensable to the development of the power of thinking, to the distinctness and variety and complexity of cognitions to the full mastery of consciousness; therefore he would fain make thought absolutely impossible without speech, identifying the faculty with its instrument. He might just as reasonably assert that the human hand cannot act without a tool. With such a doctrine to start from, he cannot stop short of Max Muller's worst paradoxes, that an infant (in fans, not speaking) is not a human being, and that deaf-mutes do not become possessed of reason until they learn to twist their fingers into imitation of spoken words." Max Muller gives in italics ('Lectures on Mr. Darwin's Philosophy of Language,' 1873, third lecture) this aphorism: "There is no thought without words, as little as there are words without thought." What a strange definition must here be given to the word thought!) With respect to animals, I have already endeavoured to shew that they have this power, at least in a rude and incipient degree. As far as concerns infants of from ten to eleven months old, and deaf-mutes, it seems to me incredible, that they should be able to connect certain sounds with certain general ideas as quickly as they do, unless such ideas were already formed in their minds. The same remark may be extended to the more intelligent animals; as Mr. Leslie Stephen observes (64. 'Essays on Free Thinking,' etc., 1873, p. 82.), "A dog frames a general concept of cats or sheep, and knows the corresponding words as well as a philosopher. And the capacity to understand is as good a proof of vocal intelligence, though in an inferior degree, as the capacity to speak." Why the organs now used for speech should have been originally perfected for this purpose, rather than any other organs, it is not difficult to see. Ants have considerable powers of intercommunication by means of their antennae, as shewn by Huber, who devotes a whole chapter to their language. We might have used our fingers as efficient instruments, for a person with practice can report to a deaf man every word of a speech rapidly delivered at a public meeting; but the loss of our hands, whilst thus employed, would have been a serious inconvenience. As all the higher mammals possess vocal organs, constructed on the same general plan as ours, and used as a means of communication, it was obviously probable that these same organs would be still further developed if the power of communication had to be improved; and this has been effected by the aid of adjoining and well adapted parts, namely the tongue and lips. (65. See some good remarks to this effect by Dr. Maudsley, 'The Physiology and Pathology of Mind,' 1868, p. 199.) The fact of the higher apes not using their vocal organs for speech, no doubt depends on their intelligence not having been sufficiently advanced. The possession by them of organs, which with long-continued practice might have been used for speech, although not thus used, is paralleled by the case of many birds which possess organs fitted for singing, though they never sing. Thus, the nightingale and crow have vocal organs similarly constructed, these being used by the former for diversified song, and by the latter only for croaking. (66. Macgillivray, 'Hist. of British Birds,' vol. ii. 1839, p. 29. An excellent observer, Mr. Blackwall, remarks that the magpie learns to pronounce single words, and even short sentences, more readily than almost any other British bird; yet, as he adds, after long and closely investigating its habits, he has never known it, in a state of nature, display any unusual capacity for imitation. 'Researches in Zoology,' 1834, p. 158.) If it be asked why apes have not had their intellects developed to the same degree as that of man, general causes only can be assigned in answer, and it is unreasonable to expect any thing more definite, considering our ignorance with respect to the successive stages of development through which each creature has passed. The formation of different languages and of distinct species, and the proofs that both have been developed through a gradual process, are curiously parallel. (67. See the very interesting parallelism between the development of species and languages, given by Sir C. Lyell in 'The Geological Evidences of the Antiquity of Man,' 1863, chap. xxiii.) But we can trace the formation of many words further back than that of species, for we can perceive how they actually arose from the imitation of various sounds. We find in distinct languages striking homologies due to community of descent, and analogies due to a similar process of formation. The manner in which certain letters or sounds change when others change is very like correlated growth. We have in both cases the reduplication of parts, the effects of long-continued use, and so forth. The frequent presence of rudiments, both in languages and in species, is still more remarkable. The letter m in the word am, means I; so that in the expression I am, a superfluous and useless rudiment has been retained. In the spelling also of words, letters often remain as the rudiments of ancient forms of pronunciation. Languages, like organic beings, can be classed in groups under groups; and they can be classed either naturally according to descent, or artificially by other characters. Dominant languages and dialects spread widely, and lead to the gradual extinction of other tongues. A language, like a species, when once extinct, never, as Sir C. Lyell remarks, reappears. The same language never has two birth-places. Distinct languages may be crossed or blended together. (68. See remarks to this effect by the Rev. F.W. Farrar, in an interesting article, entitled 'Philology and Darwinism,' in 'Nature,' March 24th, 1870, p. 528.) We see variability in every tongue, and new words are continually cropping up; but as there is a limit to the powers of the memory, single words, like whole languages, gradually become extinct. As Max Muller (69. 'Nature,' January 6th, 1870, p. 257.) has well remarked:--"A struggle for life is constantly going on amongst the words and grammatical forms in each language. The better, the shorter, the easier forms are constantly gaining the upper hand, and they owe their success to their own inherent virtue." To these more important causes of the survival of certain words, mere novelty and fashion may be added; for there is in the mind of man a strong love for slight changes in all things. The survival or preservation of certain favoured words in the struggle for existence is natural selection. The perfectly regular and wonderfully complex construction of the languages of many barbarous nations has often been advanced as a proof, either of the divine origin of these languages, or of the high art and former civilisation of their founders. Thus F. von Schlegel writes: "In those languages which appear to be at the lowest grade of intellectual culture, we frequently observe a very high and elaborate degree of art in their grammatical structure. This is especially the case with the Basque and the Lapponian, and many of the American languages." (70. Quoted by C.S. Wake, 'Chapters on Man,' 1868, p. 101.) But it is assuredly an error to speak of any language as an art, in the sense of its having been elaborately and methodically formed. Philologists now admit that conjugations, declensions, etc., originally existed as distinct words, since joined together; and as such words express the most obvious relations between objects and persons, it is not surprising that they should have been used by the men of most races during the earliest ages. With respect to perfection, the following illustration will best shew how easily we may err: a Crinoid sometimes consists of no less than 150,000 pieces of shell (71. Buckland, 'Bridgewater Treatise,' p. 411.), all arranged with perfect symmetry in radiating lines; but a naturalist does not consider an animal of this kind as more perfect than a bilateral one with comparatively few parts, and with none of these parts alike, excepting on the opposite sides of the body. He justly considers the differentiation and specialisation of organs as the test of perfection. So with languages: the most symmetrical and complex ought not to be ranked above irregular, abbreviated, and bastardised languages, which have borrowed expressive words and useful forms of construction from various conquering, conquered, or immigrant races. From these few and imperfect remarks I conclude that the extremely complex and regular construction of many barbarous languages, is no proof that they owe their origin to a special act of creation. (72. See some good remarks on the simplification of languages, by Sir J. Lubbock, 'Origin of Civilisation,' 1870, p. 278.) Nor, as we have seen, does the faculty of articulate speech in itself offer any insuperable objection to the belief that man has been developed from some lower form. SENSE OF BEAUTY. This sense has been declared to be peculiar to man. I refer here only to the pleasure given by certain colours, forms, and sounds, and which may fairly be called a sense of the beautiful; with cultivated men such sensations are, however, intimately associated with complex ideas and trains of thought. When we behold a male bird elaborately displaying his graceful plumes or splendid colours before the female, whilst other birds, not thus decorated, make no such display, it is impossible to doubt that she admires the beauty of her male partner. As women everywhere deck themselves with these plumes, the beauty of such ornaments cannot be disputed. As we shall see later, the nests of humming-birds, and the playing passages of bower-birds are tastefully ornamented with gaily-coloured objects; and this shews that they must receive some kind of pleasure from the sight of such things. With the great majority of animals, however, the taste for the beautiful is confined, as far as we can judge, to the attractions of the opposite sex. The sweet strains poured forth by many male birds during the season of love, are certainly admired by the females, of which fact evidence will hereafter be given. If female birds had been incapable of appreciating the beautiful colours, the ornaments, and voices of their male partners, all the labour and anxiety exhibited by the latter in displaying their charms before the females would have been thrown away; and this it is impossible to admit. Why certain bright colours should excite pleasure cannot, I presume, be explained, any more than why certain flavours and scents are agreeable; but habit has something to do with the result, for that which is at first unpleasant to our senses, ultimately becomes pleasant, and habits are inherited. With respect to sounds, Helmholtz has explained to a certain extent on physiological principles, why harmonies and certain cadences are agreeable. But besides this, sounds frequently recurring at irregular intervals are highly disagreeable, as every one will admit who has listened at night to the irregular flapping of a rope on board ship. The same principle seems to come into play with vision, as the eye prefers symmetry or figures with some regular recurrence. Patterns of this kind are employed by even the lowest savages as ornaments; and they have been developed through sexual selection for the adornment of some male animals. Whether we can or not give any reason for the pleasure thus derived from vision and hearing, yet man and many of the lower animals are alike pleased by the same colours, graceful shading and forms, and the same sounds. The taste for the beautiful, at least as far as female beauty is concerned, is not of a special nature in the human mind; for it differs widely in the different races of man, and is not quite the same even in the different nations of the same race. Judging from the hideous ornaments, and the equally hideous music admired by most savages, it might be urged that their aesthetic faculty was not so highly developed as in certain animals, for instance, as in birds. Obviously no animal would be capable of admiring such scenes as the heavens at night, a beautiful landscape, or refined music; but such high tastes are acquired through culture, and depend on complex associations; they are not enjoyed by barbarians or by uneducated persons. Many of the faculties, which have been of inestimable service to man for his progressive advancement, such as the powers of the imagination, wonder, curiosity, an undefined sense of beauty, a tendency to imitation, and the love of excitement or novelty, could hardly fail to lead to capricious changes of customs and fashions. I have alluded to this point, because a recent writer (73. 'The Spectator,' Dec. 4th, 1869, p. 1430.) has oddly fixed on Caprice "as one of the most remarkable and typical differences between savages and brutes." But not only can we partially understand how it is that man is from various conflicting influences rendered capricious, but that the lower animals are, as we shall hereafter see, likewise capricious in their affections, aversions, and sense of beauty. There is also reason to suspect that they love novelty, for its own sake. BELIEF IN GOD--RELIGION. There is no evidence that man was aboriginally endowed with the ennobling belief in the existence of an Omnipotent God. On the contrary there is ample evidence, derived not from hasty travellers, but from men who have long resided with savages, that numerous races have existed, and still exist, who have no idea of one or more gods, and who have no words in their languages to express such an idea. (74. See an excellent article on this subject by the Rev. F.W. Farrar, in the 'Anthropological Review,' Aug. 1864, p. ccxvii. For further facts see Sir J. Lubbock, 'Prehistoric Times,' 2nd edit., 1869, p. 564; and especially the chapters on Religion in his 'Origin of Civilisation,' 1870.) The question is of course wholly distinct from that higher one, whether there exists a Creator and Ruler of the universe; and this has been answered in the affirmative by some of the highest intellects that have ever existed. If, however, we include under the term "religion" the belief in unseen or spiritual agencies, the case is wholly different; for this belief seems to be universal with the less civilised races. Nor is it difficult to comprehend how it arose. As soon as the important faculties of the imagination, wonder, and curiosity, together with some power of reasoning, had become partially developed, man would naturally crave to understand what was passing around him, and would have vaguely speculated on his own existence. As Mr. M'Lennan (75. 'The Worship of Animals and Plants,' in the 'Fortnightly Review,' Oct. 1, 1869, p. 422.) has remarked, "Some explanation of the phenomena of life, a man must feign for himself, and to judge from the universality of it, the simplest hypothesis, and the first to occur to men, seems to have been that natural phenomena are ascribable to the presence in animals, plants, and things, and in the forces of nature, of such spirits prompting to action as men are conscious they themselves possess." It is also probable, as Mr. Tylor has shewn, that dreams may have first given rise to the notion of spirits; for savages do not readily distinguish between subjective and objective impressions. When a savage dreams, the figures which appear before him are believed to have come from a distance, and to stand over him; or "the soul of the dreamer goes out on its travels, and comes home with a remembrance of what it has seen." (76. Tylor, 'Early History of Mankind,' 1865, p. 6. See also the three striking chapters on the 'Development of Religion,' in Lubbock's 'Origin of Civilisation,' 1870. In a like manner Mr. Herbert Spencer, in his ingenious essay in the 'Fortnightly Review' (May 1st, 1870, p. 535), accounts for the earliest forms of religious belief throughout the world, by man being led through dreams, shadows, and other causes, to look at himself as a double essence, corporeal and spiritual. As the spiritual being is supposed to exist after death and to be powerful, it is propitiated by various gifts and ceremonies, and its aid invoked. He then further shews that names or nicknames given from some animal or other object, to the early progenitors or founders of a tribe, are supposed after a long interval to represent the real progenitor of the tribe; and such animal or object is then naturally believed still to exist as a spirit, is held sacred, and worshipped as a god. Nevertheless I cannot but suspect that there is a still earlier and ruder stage, when anything which manifests power or movement is thought to be endowed with some form of life, and with mental faculties analogous to our own.) But until the faculties of imagination, curiosity, reason, etc., had been fairly well developed in the mind of man, his dreams would not have led him to believe in spirits, any more than in the case of a dog. The tendency in savages to imagine that natural objects and agencies are animated by spiritual or living essences, is perhaps illustrated by a little fact which I once noticed: my dog, a full-grown and very sensible animal, was lying on the lawn during a hot and still day; but at a little distance a slight breeze occasionally moved an open parasol, which would have been wholly disregarded by the dog, had any one stood near it. As it was, every time that the parasol slightly moved, the dog growled fiercely and barked. He must, I think, have reasoned to himself in a rapid and unconscious manner, that movement without any apparent cause indicated the presence of some strange living agent, and that no stranger had a right to be on his territory. The belief in spiritual agencies would easily pass into the belief in the existence of one or more gods. For savages would naturally attribute to spirits the same passions, the same love of vengeance or simplest form of justice, and the same affections which they themselves feel. The Fuegians appear to be in this respect in an intermediate condition, for when the surgeon on board the "Beagle" shot some young ducklings as specimens, York Minster declared in the most solemn manner, "Oh, Mr. Bynoe, much rain, much snow, blow much"; and this was evidently a retributive punishment for wasting human food. So again he related how, when his brother killed a "wild man," storms long raged, much rain and snow fell. Yet we could never discover that the Fuegians believed in what we should call a God, or practised any religious rites; and Jemmy Button, with justifiable pride, stoutly maintained that there was no devil in his land. This latter assertion is the more remarkable, as with savages the belief in bad spirits is far more common than that in good ones. The feeling of religious devotion is a highly complex one, consisting of love, complete submission to an exalted and mysterious superior, a strong sense of dependence (77. See an able article on the 'Physical Elements of Religion,' by Mr. L. Owen Pike, in 'Anthropological Review,' April 1870, p. lxiii.), fear, reverence, gratitude, hope for the future, and perhaps other elements. No being could experience so complex an emotion until advanced in his intellectual and moral faculties to at least a moderately high level. Nevertheless, we see some distant approach to this state of mind in the deep love of a dog for his master, associated with complete submission, some fear, and perhaps other feelings. The behaviour of a dog when returning to his master after an absence, and, as I may add, of a monkey to his beloved keeper, is widely different from that towards their fellows. In the latter case the transports of joy appear to be somewhat less, and the sense of equality is shewn in every action. Professor Braubach goes so far as to maintain that a dog looks on his master as on a god. (78. 'Religion, Moral, etc., der Darwin'schen Art-Lehre,' 1869, s. 53. It is said (Dr. W. Lauder Lindsay, 'Journal of Mental Science,' 1871, p. 43), that Bacon long ago, and the poet Burns, held the same notion.) The same high mental faculties which first led man to believe in unseen spiritual agencies, then in fetishism, polytheism, and ultimately in monotheism, would infallibly lead him, as long as his reasoning powers remained poorly developed, to various strange superstitions and customs. Many of these are terrible to think of--such as the sacrifice of human beings to a blood-loving god; the trial of innocent persons by the ordeal of poison or fire; witchcraft, etc.--yet it is well occasionally to reflect on these superstitions, for they shew us what an infinite debt of gratitude we owe to the improvement of our reason, to science, and to our accumulated knowledge. As Sir J. Lubbock (79. 'Prehistoric Times,' 2nd edit., p. 571. In this work (p. 571) there will be found an excellent account of the many strange and capricious customs of savages.) has well observed, "it is not too much to say that the horrible dread of unknown evil hangs like a thick cloud over savage life, and embitters every pleasure." These miserable and indirect consequences of our highest faculties may be compared with the incidental and occasional mistakes of the instincts of the lower animals. CHAPTER IV. COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS--continued. The moral sense--Fundamental proposition--The qualities of social animals--Origin of sociability--Struggle between opposed instincts--Man a social animal--The more enduring social instincts conquer other less persistent instincts--The social virtues alone regarded by savages--The self-regarding virtues acquired at a later stage of development--The importance of the judgment of the members of the same community on conduct--Transmission of moral tendencies--Summary. I fully subscribe to the judgment of those writers (1. See, for instance, on this subject, Quatrefages, 'Unité de l'Espèce Humaine,' 1861, p. 21, etc.) who maintain that of all the differences between man and the lower animals, the moral sense or conscience is by far the most important. This sense, as Mackintosh (2. 'Dissertation on Ethical Philosophy,' 1837, p. 231, etc.) remarks, "has a rightful supremacy over every other principle of human action"; it is summed up in that short but imperious word "ought," so full of high significance. It is the most noble of all the attributes of man, leading him without a moment's hesitation to risk his life for that of a fellow-creature; or after due deliberation, impelled simply by the deep feeling of right or duty, to sacrifice it in some great cause. Immanuel Kant exclaims, "Duty! Wondrous thought, that workest neither by fond insinuation, flattery, nor by any threat, but merely by holding up thy naked law in the soul, and so extorting for thyself always reverence, if not always obedience; before whom all appetites are dumb, however secretly they rebel; whence thy original?" (3. 'Metaphysics of Ethics,' translated by J.W. Semple, Edinburgh, 1836, p. 136.) This great question has been discussed by many writers (4. Mr. Bain gives a list ('Mental and Moral Science,' 1868, pp. 543-725) of twenty-six British authors who have written on this subject, and whose names are familiar to every reader; to these, Mr. Bain's own name, and those of Mr. Lecky, Mr. Shadworth Hodgson, Sir J. Lubbock, and others, might be added.) of consummate ability; and my sole excuse for touching on it, is the impossibility of here passing it over; and because, as far as I know, no one has approached it exclusively from the side of natural history. The investigation possesses, also, some independent interest, as an attempt to see how far the study of the lower animals throws light on one of the highest psychical faculties of man. The following proposition seems to me in a high degree probable--namely, that any animal whatever, endowed with well-marked social instincts (5. Sir B. Brodie, after observing that man is a social animal ('Psychological Enquiries,' 1854, p. 192), asks the pregnant question, "ought not this to settle the disputed question as to the existence of a moral sense?" Similar ideas have probably occurred to many persons, as they did long ago to Marcus Aurelius. Mr. J.S. Mill speaks, in his celebrated work, 'Utilitarianism,' (1864, pp. 45, 46), of the social feelings as a "powerful natural sentiment," and as "the natural basis of sentiment for utilitarian morality." Again he says, "Like the other acquired capacities above referred to, the moral faculty, if not a part of our nature, is a natural out-growth from it; capable, like them, in a certain small degree of springing up spontaneously." But in opposition to all this, he also remarks, "if, as in my own belief, the moral feelings are not innate, but acquired, they are not for that reason less natural." It is with hesitation that I venture to differ at all from so profound a thinker, but it can hardly be disputed that the social feelings are instinctive or innate in the lower animals; and why should they not be so in man? Mr. Bain (see, for instance, 'The Emotions and the Will,' 1865, p. 481) and others believe that the moral sense is acquired by each individual during his lifetime. On the general theory of evolution this is at least extremely improbable. The ignoring of all transmitted mental qualities will, as it seems to me, be hereafter judged as a most serious blemish in the works of Mr. Mill.), the parental and filial affections being here included, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well, or nearly as well developed, as in man. For, FIRSTLY, the social instincts lead an animal to take pleasure in the society of its fellows, to feel a certain amount of sympathy with them, and to perform various services for them. The services may be of a definite and evidently instinctive nature; or there may be only a wish and readiness, as with most of the higher social animals, to aid their fellows in certain general ways. But these feelings and services are by no means extended to all the individuals of the same species, only to those of the same association. SECONDLY, as soon as the mental faculties had become highly developed, images of all past actions and motives would be incessantly passing through the brain of each individual: and that feeling of dissatisfaction, or even misery, which invariably results, as we shall hereafter see, from any unsatisfied instinct, would arise, as often as it was perceived that the enduring and always present social instinct had yielded to some other instinct, at the time stronger, but neither enduring in its nature, nor leaving behind it a very vivid impression. It is clear that many instinctive desires, such as that of hunger, are in their nature of short duration; and after being satisfied, are not readily or vividly recalled. THIRDLY, after the power of language had been acquired, and the wishes of the community could be expressed, the common opinion how each member ought to act for the public good, would naturally become in a paramount degree the guide to action. But it should be borne in mind that however great weight we may attribute to public opinion, our regard for the approbation and disapprobation of our fellows depends on sympathy, which, as we shall see, forms an essential part of the social instinct, and is indeed its foundation-stone. LASTLY, habit in the individual would ultimately play a very important part in guiding the conduct of each member; for the social instinct, together with sympathy, is, like any other instinct, greatly strengthened by habit, and so consequently would be obedience to the wishes and judgment of the community. These several subordinate propositions must now be discussed, and some of them at considerable length. It may be well first to premise that I do not wish to maintain that any strictly social animal, if its intellectual faculties were to become as active and as highly developed as in man, would acquire exactly the same moral sense as ours. In the same manner as various animals have some sense of beauty, though they admire widely-different objects, so they might have a sense of right and wrong, though led by it to follow widely different lines of conduct. If, for instance, to take an extreme case, men were reared under precisely the same conditions as hive-bees, there can hardly be a doubt that our unmarried females would, like the worker-bees, think it a sacred duty to kill their brothers, and mothers would strive to kill their fertile daughters; and no one would think of interfering. (6. Mr. H. Sidgwick remarks, in an able discussion on this subject (the 'Academy,' June 15, 1872, p. 231), "a superior bee, we may feel sure, would aspire to a milder solution of the population question." Judging, however, from the habits of many or most savages, man solves the problem by female infanticide, polyandry and promiscuous intercourse; therefore it may well be doubted whether it would be by a milder method. Miss Cobbe, in commenting ('Darwinism in Morals,' 'Theological Review,' April 1872, pp. 188-191) on the same illustration, says, the PRINCIPLES of social duty would be thus reversed; and by this, I presume, she means that the fulfilment of a social duty would tend to the injury of individuals; but she overlooks the fact, which she would doubtless admit, that the instincts of the bee have been acquired for the good of the community. She goes so far as to say that if the theory of ethics advocated in this chapter were ever generally accepted, "I cannot but believe that in the hour of their triumph would be sounded the knell of the virtue of mankind!" It is to be hoped that the belief in the permanence of virtue on this earth is not held by many persons on so weak a tenure.) Nevertheless, the bee, or any other social animal, would gain in our supposed case, as it appears to me, some feeling of right or wrong, or a conscience. For each individual would have an inward sense of possessing certain stronger or more enduring instincts, and others less strong or enduring; so that there would often be a struggle as to which impulse should be followed; and satisfaction, dissatisfaction, or even misery would be felt, as past impressions were compared during their incessant passage through the mind. In this case an inward monitor would tell the animal that it would have been better to have followed the one impulse rather than the other. The one course ought to have been followed, and the other ought not; the one would have been right and the other wrong; but to these terms I shall recur. SOCIABILITY. Animals of many kinds are social; we find even distinct species living together; for example, some American monkeys; and united flocks of rooks, jackdaws, and starlings. Man shews the same feeling in his strong love for the dog, which the dog returns with interest. Every one must have noticed how miserable horses, dogs, sheep, etc., are when separated from their companions, and what strong mutual affection the two former kinds, at least, shew on their reunion. It is curious to speculate on the feelings of a dog, who will rest peacefully for hours in a room with his master or any of the family, without the least notice being taken of him; but if left for a short time by himself, barks or howls dismally. We will confine our attention to the higher social animals; and pass over insects, although some of these are social, and aid one another in many important ways. The most common mutual service in the higher animals is to warn one another of danger by means of the united senses of all. Every sportsman knows, as Dr. Jaeger remarks (7. 'Die Darwin'sche Theorie,' s. 101.), how difficult it is to approach animals in a herd or troop. Wild horses and cattle do not, I believe, make any danger-signal; but the attitude of any one of them who first discovers an enemy, warns the others. Rabbits stamp loudly on the ground with their hind-feet as a signal: sheep and chamois do the same with their forefeet, uttering likewise a whistle. Many birds, and some mammals, post sentinels, which in the case of seals are said (8. Mr. R. Brown in 'Proc. Zoolog. Soc.' 1868, p. 409.) generally to be the females. The leader of a troop of monkeys acts as the sentinel, and utters cries expressive both of danger and of safety. (9. Brehm, 'Thierleben,' B. i. 1864, s. 52, 79. For the case of the monkeys extracting thorns from each other, see s. 54. With respect to the Hamadryas turning over stones, the fact is given (s. 76), on the evidence of Alvarez, whose observations Brehm thinks quite trustworthy. For the cases of the old male baboons attacking the dogs, see s. 79; and with respect to the eagle, s. 56.) Social animals perform many little services for each other: horses nibble, and cows lick each other, on any spot which itches: monkeys search each other for external parasites; and Brehm states that after a troop of the Cercopithecus griseo-viridis has rushed through a thorny brake, each monkey stretches itself on a branch, and another monkey sitting by, "conscientiously" examines its fur, and extracts every thorn or burr. Animals also render more important services to one another: thus wolves and some other beasts of prey hunt in packs, and aid one another in attacking their victims. Pelicans fish in concert. The Hamadryas baboons turn over stones to find insects, etc.; and when they come to a large one, as many as can stand round, turn it over together and share the booty. Social animals mutually defend each other. Bull bisons in N. America, when there is danger, drive the cows and calves into the middle of the herd, whilst they defend the outside. I shall also in a future chapter give an account of two young wild bulls at Chillingham attacking an old one in concert, and of two stallions together trying to drive away a third stallion from a troop of mares. In Abyssinia, Brehm encountered a great troop of baboons who were crossing a valley: some had already ascended the opposite mountain, and some were still in the valley; the latter were attacked by the dogs, but the old males immediately hurried down from the rocks, and with mouths widely opened, roared so fearfully, that the dogs quickly drew back. They were again encouraged to the attack; but by this time all the baboons had reascended the heights, excepting a young one, about six months old, who, loudly calling for aid, climbed on a block of rock, and was surrounded. Now one of the largest males, a true hero, came down again from the mountain, slowly went to the young one, coaxed him, and triumphantly led him away--the dogs being too much astonished to make an attack. I cannot resist giving another scene which was witnessed by this same naturalist; an eagle seized a young Cercopithecus, which, by clinging to a branch, was not at once carried off; it cried loudly for assistance, upon which the other members of the troop, with much uproar, rushed to the rescue, surrounded the eagle, and pulled out so many feathers, that he no longer thought of his prey, but only how to escape. This eagle, as Brehm remarks, assuredly would never again attack a single monkey of a troop. (10. Mr. Belt gives the case of a spider-monkey (Ateles) in Nicaragua, which was heard screaming for nearly two hours in the forest, and was found with an eagle perched close by it. The bird apparently feared to attack as long as it remained face to face; and Mr. Belt believes, from what he has seen of the habits of these monkeys, that they protect themselves from eagles by keeping two or three together. 'The Naturalist in Nicaragua,' 1874, p. 118.) It is certain that associated animals have a feeling of love for each other, which is not felt by non-social adult animals. How far in most cases they actually sympathise in the pains and pleasures of others, is more doubtful, especially with respect to pleasures. Mr. Buxton, however, who had excellent means of observation (11. 'Annals and Magazine of Natural History,' November 1868, p. 382.), states that his macaws, which lived free in Norfolk, took "an extravagant interest" in a pair with a nest; and whenever the female left it, she was surrounded by a troop "screaming horrible acclamations in her honour." It is often difficult to judge whether animals have any feeling for the sufferings of others of their kind. Who can say what cows feel, when they surround and stare intently on a dying or dead companion; apparently, however, as Houzeau remarks, they feel no pity. That animals sometimes are far from feeling any sympathy is too certain; for they will expel a wounded animal from the herd, or gore or worry it to death. This is almost the blackest fact in natural history, unless, indeed, the explanation which has been suggested is true, that their instinct or reason leads them to expel an injured companion, lest beasts of prey, including man, should be tempted to follow the troop. In this case their conduct is not much worse than that of the North American Indians, who leave their feeble comrades to perish on the plains; or the Fijians, who, when their parents get old, or fall ill, bury them alive. (12. Sir J. Lubbock, 'Prehistoric Times,' 2nd ed., p. 446.) Many animals, however, certainly sympathise with each other's distress or danger. This is the case even with birds. Captain Stansbury (13. As quoted by Mr. L.H. Morgan, 'The American Beaver,' 1868, p. 272. Capt. Stansbury also gives an interesting account of the manner in which a very young pelican, carried away by a strong stream, was guided and encouraged in its attempts to reach the shore by half a dozen old birds.) found on a salt lake in Utah an old and completely blind pelican, which was very fat, and must have been well fed for a long time by his companions. Mr. Blyth, as he informs me, saw Indian crows feeding two or three of their companions which were blind; and I have heard of an analogous case with the domestic cock. We may, if we choose, call these actions instinctive; but such cases are much too rare for the development of any special instinct. (14. As Mr. Bain states, "effective aid to a sufferer springs from sympathy proper:" 'Mental and Moral Science,' 1868, p. 245.) I have myself seen a dog, who never passed a cat who lay sick in a basket, and was a great friend of his, without giving her a few licks with his tongue, the surest sign of kind feeling in a dog. It must be called sympathy that leads a courageous dog to fly at any one who strikes his master, as he certainly will. I saw a person pretending to beat a lady, who had a very timid little dog on her lap, and the trial had never been made before; the little creature instantly jumped away, but after the pretended beating was over, it was really pathetic to see how perseveringly he tried to lick his mistress's face, and comfort her. Brehm (15. 'Thierleben,' B. i. s. 85.) states that when a baboon in confinement was pursued to be punished, the others tried to protect him. It must have been sympathy in the cases above given which led the baboons and Cercopitheci to defend their young comrades from the dogs and the eagle. I will give only one other instance of sympathetic and heroic conduct, in the case of a little American monkey. Several years ago a keeper at the Zoological Gardens shewed me some deep and scarcely healed wounds on the nape of his own neck, inflicted on him, whilst kneeling on the floor, by a fierce baboon. The little American monkey, who was a warm friend of this keeper, lived in the same large compartment, and was dreadfully afraid of the great baboon. Nevertheless, as soon as he saw his friend in peril, he rushed to the rescue, and by screams and bites so distracted the baboon that the man was able to escape, after, as the surgeon thought, running great risk of his life. Besides love and sympathy, animals exhibit other qualities connected with the social instincts, which in us would be called moral; and I agree with Agassiz (16. 'De l'Espèce et de la Classe,' 1869, p. 97.) that dogs possess something very like a conscience. Dogs possess some power of self-command, and this does not appear to be wholly the result of fear. As Braubach (17. 'Die Darwin'sche Art-Lehre,' 1869, s. 54.) remarks, they will refrain from stealing food in the absence of their master. They have long been accepted as the very type of fidelity and obedience. But the elephant is likewise very faithful to his driver or keeper, and probably considers him as the leader of the herd. Dr. Hooker informs me that an elephant, which he was riding in India, became so deeply bogged that he remained stuck fast until the next day, when he was extricated by men with ropes. Under such circumstances elephants will seize with their trunks any object, dead or alive, to place under their knees, to prevent their sinking deeper in the mud; and the driver was dreadfully afraid lest the animal should have seized Dr. Hooker and crushed him to death. But the driver himself, as Dr. Hooker was assured, ran no risk. This forbearance under an emergency so dreadful for a heavy animal, is a wonderful proof of noble fidelity. (18. See also Hooker's 'Himalayan Journals,' vol. ii. 1854, p. 333.) All animals living in a body, which defend themselves or attack their enemies in concert, must indeed be in some degree faithful to one another; and those that follow a leader must be in some degree obedient. When the baboons in Abyssinia (19. Brehm, 'Thierleben,' B. i. s. 76.) plunder a garden, they silently follow their leader; and if an imprudent young animal makes a noise, he receives a slap from the others to teach him silence and obedience. Mr. Galton, who has had excellent opportunities for observing the half-wild cattle in S. Africa, says (20. See his extremely interesting paper on 'Gregariousness in Cattle, and in Man,' 'Macmillan's Magazine,' Feb. 1871, p. 353.), that they cannot endure even a momentary separation from the herd. They are essentially slavish, and accept the common determination, seeking no better lot than to be led by any one ox who has enough self-reliance to accept the position. The men who break in these animals for harness, watch assiduously for those who, by grazing apart, shew a self-reliant disposition, and these they train as fore-oxen. Mr. Galton adds that such animals are rare and valuable; and if many were born they would soon be eliminated, as lions are always on the look-out for the individuals which wander from the herd. With respect to the impulse which leads certain animals to associate together, and to aid one another in many ways, we may infer that in most cases they are impelled by the same sense of satisfaction or pleasure which they experience in performing other instinctive actions; or by the same sense of dissatisfaction as when other instinctive actions are checked. We see this in innumerable instances, and it is illustrated in a striking manner by the acquired instincts of our domesticated animals; thus a young shepherd-dog delights in driving and running round a flock of sheep, but not in worrying them; a young fox-hound delights in hunting a fox, whilst some other kinds of dogs, as I have witnessed, utterly disregard foxes. What a strong feeling of inward satisfaction must impel a bird, so full of activity, to brood day after day over her eggs. Migratory birds are quite miserable if stopped from migrating; perhaps they enjoy starting on their long flight; but it is hard to believe that the poor pinioned goose, described by Audubon, which started on foot at the proper time for its journey of probably more than a thousand miles, could have felt any joy in doing so. Some instincts are determined solely by painful feelings, as by fear, which leads to self-preservation, and is in some cases directed towards special enemies. No one, I presume, can analyse the sensations of pleasure or pain. In many instances, however, it is probable that instincts are persistently followed from the mere force of inheritance, without the stimulus of either pleasure or pain. A young pointer, when it first scents game, apparently cannot help pointing. A squirrel in a cage who pats the nuts which it cannot eat, as if to bury them in the ground, can hardly be thought to act thus, either from pleasure or pain. Hence the common assumption that men must be impelled to every action by experiencing some pleasure or pain may be erroneous. Although a habit may be blindly and implicitly followed, independently of any pleasure or pain felt at the moment, yet if it be forcibly and abruptly checked, a vague sense of dissatisfaction is generally experienced. It has often been assumed that animals were in the first place rendered social, and that they feel as a consequence uncomfortable when separated from each other, and comfortable whilst together; but it is a more probable view that these sensations were first developed, in order that those animals which would profit by living in society, should be induced to live together, in the same manner as the sense of hunger and the pleasure of eating were, no doubt, first acquired in order to induce animals to eat. The feeling of pleasure from society is probably an extension of the parental or filial affections, since the social instinct seems to be developed by the young remaining for a long time with their parents; and this extension may be attributed in part to habit, but chiefly to natural selection. With those animals which were benefited by living in close association, the individuals which took the greatest pleasure in society would best escape various dangers, whilst those that cared least for their comrades, and lived solitary, would perish in greater numbers. With respect to the origin of the parental and filial affections, which apparently lie at the base of the social instincts, we know not the steps by which they have been gained; but we may infer that it has been to a large extent through natural selection. So it has almost certainly been with the unusual and opposite feeling of hatred between the nearest relations, as with the worker-bees which kill their brother drones, and with the queen-bees which kill their daughter-queens; the desire to destroy their nearest relations having been in this case of service to the community. Parental affection, or some feeling which replaces it, has been developed in certain animals extremely low in the scale, for example, in star-fishes and spiders. It is also occasionally present in a few members alone in a whole group of animals, as in the genus Forficula, or earwigs. The all-important emotion of sympathy is distinct from that of love. A mother may passionately love her sleeping and passive infant, but she can hardly at such times be said to feel sympathy for it. The love of a man for his dog is distinct from sympathy, and so is that of a dog for his master. Adam Smith formerly argued, as has Mr. Bain recently, that the basis of sympathy lies in our strong retentiveness of former states of pain or pleasure. Hence, "the sight of another person enduring hunger, cold, fatigue, revives in us some recollection of these states, which are painful even in idea." We are thus impelled to relieve the sufferings of another, in order that our own painful feelings may be at the same time relieved. In like manner we are led to participate in the pleasures of others. (21. See the first and striking chapter in Adam Smith's 'Theory of Moral Sentiments.' Also 'Mr. Bain's Mental and Moral Science,' 1868, pp. 244, and 275-282. Mr. Bain states, that, "sympathy is, indirectly, a source of pleasure to the sympathiser"; and he accounts for this through reciprocity. He remarks that "the person benefited, or others in his stead, may make up, by sympathy and good offices returned, for all the sacrifice." But if, as appears to be the case, sympathy is strictly an instinct, its exercise would give direct pleasure, in the same manner as the exercise, as before remarked, of almost every other instinct.) But I cannot see how this view explains the fact that sympathy is excited, in an immeasurably stronger degree, by a beloved, than by an indifferent person. The mere sight of suffering, independently of love, would suffice to call up in us vivid recollections and associations. The explanation may lie in the fact that, with all animals, sympathy is directed solely towards the members of the same community, and therefore towards known, and more or less beloved members, but not to all the individuals of the same species. This fact is not more surprising than that the fears of many animals should be directed against special enemies. Species which are not social, such as lions and tigers, no doubt feel sympathy for the suffering of their own young, but not for that of any other animal. With mankind, selfishness, experience, and imitation, probably add, as Mr. Bain has shewn, to the power of sympathy; for we are led by the hope of receiving good in return to perform acts of sympathetic kindness to others; and sympathy is much strengthened by habit. In however complex a manner this feeling may have originated, as it is one of high importance to all those animals which aid and defend one another, it will have been increased through natural selection; for those communities, which included the greatest number of the most sympathetic members, would flourish best, and rear the greatest number of offspring. It is, however, impossible to decide in many cases whether certain social instincts have been acquired through natural selection, or are the indirect result of other instincts and faculties, such as sympathy, reason, experience, and a tendency to imitation; or again, whether they are simply the result of long-continued habit. So remarkable an instinct as the placing sentinels to warn the community of danger, can hardly have been the indirect result of any of these faculties; it must, therefore, have been directly acquired. On the other hand, the habit followed by the males of some social animals of defending the community, and of attacking their enemies or their prey in concert, may perhaps have originated from mutual sympathy; but courage, and in most cases strength, must have been previously acquired, probably through natural selection. Of the various instincts and habits, some are much stronger than others; that is, some either give more pleasure in their performance, and more distress in their prevention, than others; or, which is probably quite as important, they are, through inheritance, more persistently followed, without exciting any special feeling of pleasure or pain. We are ourselves conscious that some habits are much more difficult to cure or change than others. Hence a struggle may often be observed in animals between different instincts, or between an instinct and some habitual disposition; as when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues again, or returns ashamed to his master; or as between the love of a female dog for her young puppies and for her master,--for she may be seen to slink away to them, as if half ashamed of not accompanying her master. But the most curious instance known to me of one instinct getting the better of another, is the migratory instinct conquering the maternal instinct. The former is wonderfully strong; a confined bird will at the proper season beat her breast against the wires of her cage, until it is bare and bloody. It causes young salmon to leap out of the fresh water, in which they could continue to exist, and thus unintentionally to commit suicide. Every one knows how strong the maternal instinct is, leading even timid birds to face great danger, though with hesitation, and in opposition to the instinct of self-preservation. Nevertheless, the migratory instinct is so powerful, that late in the autumn swallows, house-martins, and swifts frequently desert their tender young, leaving them to perish miserably in their nests. (22. This fact, the Rev. L. Jenyns states (see his edition of 'White's Nat. Hist. of Selborne,' 1853, p. 204) was first recorded by the illustrious Jenner, in 'Phil. Transact.' 1824, and has since been confirmed by several observers, especially by Mr. Blackwall. This latter careful observer examined, late in the autumn, during two years, thirty-six nests; he found that twelve contained young dead birds, five contained eggs on the point of being hatched, and three, eggs not nearly hatched. Many birds, not yet old enough for a prolonged flight, are likewise deserted and left behind. See Blackwall, 'Researches in Zoology,' 1834, pp. 108, 118. For some additional evidence, although this is not wanted, see Leroy, 'Lettres Phil.' 1802, p. 217. For Swifts, Gould's 'Introduction to the Birds of Great Britain,' 1823, p. 5. Similar cases have been observed in Canada by Mr. Adams; 'Pop. Science Review,' July 1873, p. 283.) We can perceive that an instinctive impulse, if it be in any way more beneficial to a species than some other or opposed instinct, would be rendered the more potent of the two through natural selection; for the individuals which had it most strongly developed would survive in larger numbers. Whether this is the case with the migratory in comparison with the maternal instinct, may be doubted. The great persistence, or steady action of the former at certain seasons of the year during the whole day, may give it for a time paramount force. MAN A SOCIAL ANIMAL. Every one will admit that man is a social being. We see this in his dislike of solitude, and in his wish for society beyond that of his own family. Solitary confinement is one of the severest punishments which can be inflicted. Some authors suppose that man primevally lived in single families; but at the present day, though single families, or only two or three together, roam the solitudes of some savage lands, they always, as far as I can discover, hold friendly relations with other families inhabiting the same district. Such families occasionally meet in council, and unite for their common defence. It is no argument against savage man being a social animal, that the tribes inhabiting adjacent districts are almost always at war with each other; for the social instincts never extend to all the individuals of the same species. Judging from the analogy of the majority of the Quadrumana, it is probable that the early ape-like progenitors of man were likewise social; but this is not of much importance for us. Although man, as he now exists, has few special instincts, having lost any which his early progenitors may have possessed, this is no reason why he should not have retained from an extremely remote period some degree of instinctive love and sympathy for his fellows. We are indeed all conscious that we do possess such sympathetic feelings (23. Hume remarks ('An Enquiry Concerning the Principles of Morals,' edit. of 1751, p. 132), "There seems a necessity for confessing that the happiness and misery of others are not spectacles altogether indifferent to us, but that the view of the former...communicates a secret joy; the appearance of the latter... throws a melancholy damp over the imagination."); but our consciousness does not tell us whether they are instinctive, having originated long ago in the same manner as with the lower animals, or whether they have been acquired by each of us during our early years. As man is a social animal, it is almost certain that he would inherit a tendency to be faithful to his comrades, and obedient to the leader of his tribe; for these qualities are common to most social animals. He would consequently possess some capacity for self-command. He would from an inherited tendency be willing to defend, in concert with others, his fellow-men; and would be ready to aid them in any way, which did not too greatly interfere with his own welfare or his own strong desires. The social animals which stand at the bottom of the scale are guided almost exclusively, and those which stand higher in the scale are largely guided, by special instincts in the aid which they give to the members of the same community; but they are likewise in part impelled by mutual love and sympathy, assisted apparently by some amount of reason. Although man, as just remarked, has no special instincts to tell him how to aid his fellow-men, he still has the impulse, and with his improved intellectual faculties would naturally be much guided in this respect by reason and experience. Instinctive sympathy would also cause him to value highly the approbation of his fellows; for, as Mr. Bain has clearly shewn (24. 'Mental and Moral Science,' 1868, p. 254.), the love of praise and the strong feeling of glory, and the still stronger horror of scorn and infamy, "are due to the workings of sympathy." Consequently man would be influenced in the highest degree by the wishes, approbation, and blame of his fellow-men, as expressed by their gestures and language. Thus the social instincts, which must have been acquired by man in a very rude state, and probably even by his early ape-like progenitors, still give the impulse to some of his best actions; but his actions are in a higher degree determined by the expressed wishes and judgment of his fellow-men, and unfortunately very often by his own strong selfish desires. But as love, sympathy and self-command become strengthened by habit, and as the power of reasoning becomes clearer, so that man can value justly the judgments of his fellows, he will feel himself impelled, apart from any transitory pleasure or pain, to certain lines of conduct. He might then declare--not that any barbarian or uncultivated man could thus think--I am the supreme judge of my own conduct, and in the words of Kant, I will not in my own person violate the dignity of humanity. THE MORE ENDURING SOCIAL INSTINCTS CONQUER THE LESS PERSISTENT INSTINCTS. We have not, however, as yet considered the main point, on which, from our present point of view, the whole question of the moral sense turns. Why should a man feel that he ought to obey one instinctive desire rather than another? Why is he bitterly regretful, if he has yielded to a strong sense of self-preservation, and has not risked his life to save that of a fellow-creature? or why does he regret having stolen food from hunger? It is evident in the first place, that with mankind the instinctive impulses have different degrees of strength; a savage will risk his own life to save that of a member of the same community, but will be wholly indifferent about a stranger: a young and timid mother urged by the maternal instinct will, without a moment's hesitation, run the greatest danger for her own infant, but not for a mere fellow-creature. Nevertheless many a civilised man, or even boy, who never before risked his life for another, but full of courage and sympathy, has disregarded the instinct of self-preservation, and plunged at once into a torrent to save a drowning man, though a stranger. In this case man is impelled by the same instinctive motive, which made the heroic little American monkey, formerly described, save his keeper, by attacking the great and dreaded baboon. Such actions as the above appear to be the simple result of the greater strength of the social or maternal instincts rather than that of any other instinct or motive; for they are performed too instantaneously for reflection, or for pleasure or pain to be felt at the time; though, if prevented by any cause, distress or even misery might be felt. In a timid man, on the other hand, the instinct of self-preservation might be so strong, that he would be unable to force himself to run any such risk, perhaps not even for his own child. I am aware that some persons maintain that actions performed impulsively, as in the above cases, do not come under the dominion of the moral sense, and cannot be called moral. They confine this term to actions done deliberately, after a victory over opposing desires, or when prompted by some exalted motive. But it appears scarcely possible to draw any clear line of distinction of this kind. (25. I refer here to the distinction between what has been called MATERIAL and FORMAL morality. I am glad to find that Professor Huxley ('Critiques and Addresses,' 1873, p. 287) takes the same view on this subject as I do. Mr. Leslie Stephen remarks ('Essays on Freethinking and Plain Speaking,' 1873, p. 83), "the metaphysical distinction, between material and formal morality is as irrelevant as other such distinctions.") As far as exalted motives are concerned, many instances have been recorded of savages, destitute of any feeling of general benevolence towards mankind, and not guided by any religious motive, who have deliberately sacrificed their lives as prisoners(26. I have given one such case, namely of three Patagonian Indians who preferred being shot, one after the other, to betraying the plans of their companions in war ('Journal of Researches,' 1845, p. 103).), rather than betray their comrades; and surely their conduct ought to be considered as moral. As far as deliberation, and the victory over opposing motives are concerned, animals may be seen doubting between opposed instincts, in rescuing their offspring or comrades from danger; yet their actions, though done for the good of others, are not called moral. Moreover, anything performed very often by us, will at last be done without deliberation or hesitation, and can then hardly be distinguished from an instinct; yet surely no one will pretend that such an action ceases to be moral. On the contrary, we all feel that an act cannot be considered as perfect, or as performed in the most noble manner, unless it be done impulsively, without deliberation or effort, in the same manner as by a man in whom the requisite qualities are innate. He who is forced to overcome his fear or want of sympathy before he acts, deserves, however, in one way higher credit than the man whose innate disposition leads him to a good act without effort. As we cannot distinguish between motives, we rank all actions of a certain class as moral, if performed by a moral being. A moral being is one who is capable of comparing his past and future actions or motives, and of approving or disapproving of them. We have no reason to suppose that any of the lower animals have this capacity; therefore, when a Newfoundland dog drags a child out of the water, or a monkey faces danger to rescue its comrade, or takes charge of an orphan monkey, we do not call its conduct moral. But in the case of man, who alone can with certainty be ranked as a moral being, actions of a certain class are called moral, whether performed deliberately, after a struggle with opposing motives, or impulsively through instinct, or from the effects of slowly-gained habit. But to return to our more immediate subject. Although some instincts are more powerful than others, and thus lead to corresponding actions, yet it is untenable, that in man the social instincts (including the love of praise and fear of blame) possess greater strength, or have, through long habit, acquired greater strength than the instincts of self-preservation, hunger, lust, vengeance, etc. Why then does man regret, even though trying to banish such regret, that he has followed the one natural impulse rather than the other; and why does he further feel that he ought to regret his conduct? Man in this respect differs profoundly from the lower animals. Nevertheless we can, I think, see with some degree of clearness the reason of this difference. Man, from the activity of his mental faculties, cannot avoid reflection: past impressions and images are incessantly and clearly passing through his mind. Now with those animals which live permanently in a body, the social instincts are ever present and persistent. Such animals are always ready to utter the danger-signal, to defend the community, and to give aid to their fellows in accordance with their habits; they feel at all times, without the stimulus of any special passion or desire, some degree of love and sympathy for them; they are unhappy if long separated from them, and always happy to be again in their company. So it is with ourselves. Even when we are quite alone, how often do we think with pleasure or pain of what others think of us,--of their imagined approbation or disapprobation; and this all follows from sympathy, a fundamental element of the social instincts. A man who possessed no trace of such instincts would be an unnatural monster. On the other hand, the desire to satisfy hunger, or any passion such as vengeance, is in its nature temporary, and can for a time be fully satisfied. Nor is it easy, perhaps hardly possible, to call up with complete vividness the feeling, for instance, of hunger; nor indeed, as has often been remarked, of any suffering. The instinct of self-preservation is not felt except in the presence of danger; and many a coward has thought himself brave until he has met his enemy face to face. The wish for another man's property is perhaps as persistent a desire as any that can be named; but even in this case the satisfaction of actual possession is generally a weaker feeling than the desire: many a thief, if not a habitual one, after success has wondered why he stole some article. (27. Enmity or hatred seems also to be a highly persistent feeling, perhaps more so than any other that can be named. Envy is defined as hatred of another for some excellence or success; and Bacon insists (Essay ix.), "Of all other affections envy is the most importune and continual." Dogs are very apt to hate both strange men and strange dogs, especially if they live near at hand, but do not belong to the same family, tribe, or clan; this feeling would thus seem to be innate, and is certainly a most persistent one. It seems to be the complement and converse of the true social instinct. From what we hear of savages, it would appear that something of the same kind holds good with them. If this be so, it would be a small step in any one to transfer such feelings to any member of the same tribe if he had done him an injury and had become his enemy. Nor is it probable that the primitive conscience would reproach a man for injuring his enemy; rather it would reproach him, if he had not revenged himself. To do good in return for evil, to love your enemy, is a height of morality to which it may be doubted whether the social instincts would, by themselves, have ever led us. It is necessary that these instincts, together with sympathy, should have been highly cultivated and extended by the aid of reason, instruction, and the love or fear of God, before any such golden rule would ever be thought of and obeyed.) A man cannot prevent past impressions often repassing through his mind; he will thus be driven to make a comparison between the impressions of past hunger, vengeance satisfied, or danger shunned at other men's cost, with the almost ever-present instinct of sympathy, and with his early knowledge of what others consider as praiseworthy or blameable. This knowledge cannot be banished from his mind, and from instinctive sympathy is esteemed of great moment. He will then feel as if he had been baulked in following a present instinct or habit, and this with all animals causes dissatisfaction, or even misery. The above case of the swallow affords an illustration, though of a reversed nature, of a temporary though for the time strongly persistent instinct conquering another instinct, which is usually dominant over all others. At the proper season these birds seem all day long to be impressed with the desire to migrate; their habits change; they become restless, are noisy and congregate in flocks. Whilst the mother-bird is feeding, or brooding over her nestlings, the maternal instinct is probably stronger than the migratory; but the instinct which is the more persistent gains the victory, and at last, at a moment when her young ones are not in sight, she takes flight and deserts them. When arrived at the end of her long journey, and the migratory instinct has ceased to act, what an agony of remorse the bird would feel, if, from being endowed with great mental activity, she could not prevent the image constantly passing through her mind, of her young ones perishing in the bleak north from cold and hunger. At the moment of action, man will no doubt be apt to follow the stronger impulse; and though this may occasionally prompt him to the noblest deeds, it will more commonly lead him to gratify his own desires at the expense of other men. But after their gratification when past and weaker impressions are judged by the ever-enduring social instinct, and by his deep regard for the good opinion of his fellows, retribution will surely come. He will then feel remorse, repentance, regret, or shame; this latter feeling, however, relates almost exclusively to the judgment of others. He will consequently resolve more or less firmly to act differently for the future; and this is conscience; for conscience looks backwards, and serves as a guide for the future. The nature and strength of the feelings which we call regret, shame, repentance or remorse, depend apparently not only on the strength of the violated instinct, but partly on the strength of the temptation, and often still more on the judgment of our fellows. How far each man values the appreciation of others, depends on the strength of his innate or acquired feeling of sympathy; and on his own capacity for reasoning out the remote consequences of his acts. Another element is most important, although not necessary, the reverence or fear of the Gods, or Spirits believed in by each man: and this applies especially in cases of remorse. Several critics have objected that though some slight regret or repentance may be explained by the view advocated in this chapter, it is impossible thus to account for the soul-shaking feeling of remorse. But I can see little force in this objection. My critics do not define what they mean by remorse, and I can find no definition implying more than an overwhelming sense of repentance. Remorse seems to bear the same relation to repentance, as rage does to anger, or agony to pain. It is far from strange that an instinct so strong and so generally admired, as maternal love, should, if disobeyed, lead to the deepest misery, as soon as the impression of the past cause of disobedience is weakened. Even when an action is opposed to no special instinct, merely to know that our friends and equals despise us for it is enough to cause great misery. Who can doubt that the refusal to fight a duel through fear has caused many men an agony of shame? Many a Hindoo, it is said, has been stirred to the bottom of his soul by having partaken of unclean food. Here is another case of what must, I think, be called remorse. Dr. Landor acted as a magistrate in West Australia, and relates (28. 'Insanity in Relation to Law,' Ontario, United States, 1871, p. 1.), that a native on his farm, after losing one of his wives from disease, came and said that, "he was going to a distant tribe to spear a woman, to satisfy his sense of duty to his wife. I told him that if he did so, I would send him to prison for life. He remained about the farm for some months, but got exceedingly thin, and complained that he could not rest or eat, that his wife's spirit was haunting him, because he had not taken a life for hers. I was inexorable, and assured him that nothing should save him if he did." Nevertheless the man disappeared for more than a year, and then returned in high condition; and his other wife told Dr. Landor that her husband had taken the life of a woman belonging to a distant tribe; but it was impossible to obtain legal evidence of the act. The breach of a rule held sacred by the tribe, will thus, as it seems, give rise to the deepest feelings,--and this quite apart from the social instincts, excepting in so far as the rule is grounded on the judgment of the community. How so many strange superstitions have arisen throughout the world we know not; nor can we tell how some real and great crimes, such as incest, have come to be held in an abhorrence (which is not however quite universal) by the lowest savages. It is even doubtful whether in some tribes incest would be looked on with greater horror, than would the marriage of a man with a woman bearing the same name, though not a relation. "To violate this law is a crime which the Australians hold in the greatest abhorrence, in this agreeing exactly with certain tribes of North America. When the question is put in either district, is it worse to kill a girl of a foreign tribe, or to marry a girl of one's own, an answer just opposite to ours would be given without hesitation." (29. E.B. Tylor, in 'Contemporary Review,' April 1873, p. 707.) We may, therefore, reject the belief, lately insisted on by some writers, that the abhorrence of incest is due to our possessing a special God-implanted conscience. On the whole it is intelligible, that a man urged by so powerful a sentiment as remorse, though arising as above explained, should be led to act in a manner, which he has been taught to believe serves as an expiation, such as delivering himself up to justice. Man prompted by his conscience, will through long habit acquire such perfect self-command, that his desires and passions will at last yield instantly and without a struggle to his social sympathies and instincts, including his feeling for the judgment of his fellows. The still hungry, or the still revengeful man will not think of stealing food, or of wreaking his vengeance. It is possible, or as we shall hereafter see, even probable, that the habit of self-command may, like other habits, be inherited. Thus at last man comes to feel, through acquired and perhaps inherited habit, that it is best for him to obey his more persistent impulses. The imperious word "ought" seems merely to imply the consciousness of the existence of a rule of conduct, however it may have originated. Formerly it must have been often vehemently urged that an insulted gentleman OUGHT to fight a duel. We even say that a pointer OUGHT to point, and a retriever to retrieve game. If they fail to do so, they fail in their duty and act wrongly. If any desire or instinct leading to an action opposed to the good of others still appears, when recalled to mind, as strong as, or stronger than, the social instinct, a man will feel no keen regret at having followed it; but he will be conscious that if his conduct were known to his fellows, it would meet with their disapprobation; and few are so destitute of sympathy as not to feel discomfort when this is realised. If he has no such sympathy, and if his desires leading to bad actions are at the time strong, and when recalled are not over-mastered by the persistent social instincts, and the judgment of others, then he is essentially a bad man (30. Dr. Prosper Despine, in his Psychologie Naturelle, 1868 (tom. i. p. 243; tom. ii. p. 169) gives many curious cases of the worst criminals, who apparently have been entirely destitute of conscience.); and the sole restraining motive left is the fear of punishment, and the conviction that in the long run it would be best for his own selfish interests to regard the good of others rather than his own. It is obvious that every one may with an easy conscience gratify his own desires, if they do not interfere with his social instincts, that is with the good of others; but in order to be quite free from self-reproach, or at least of anxiety, it is almost necessary for him to avoid the disapprobation, whether reasonable or not, of his fellow-men. Nor must he break through the fixed habits of his life, especially if these are supported by reason; for if he does, he will assuredly feel dissatisfaction. He must likewise avoid the reprobation of the one God or gods in whom, according to his knowledge or superstition, he may believe; but in this case the additional fear of divine punishment often supervenes. THE STRICTLY SOCIAL VIRTUES AT FIRST ALONE REGARDED. The above view of the origin and nature of the moral sense, which tells us what we ought to do, and of the conscience which reproves us if we disobey it, accords well with what we see of the early and undeveloped condition of this faculty in mankind. The virtues which must be practised, at least generally, by rude men, so that they may associate in a body, are those which are still recognised as the most important. But they are practised almost exclusively in relation to the men of the same tribe; and their opposites are not regarded as crimes in relation to the men of other tribes. No tribe could hold together if murder, robbery, treachery, etc., were common; consequently such crimes within the limits of the same tribe "are branded with everlasting infamy" (31. See an able article in the 'North British Review,' 1867, p. 395. See also Mr. W. Bagehot's articles on the Importance of Obedience and Coherence to Primitive Man, in the 'Fortnightly Review,' 1867, p. 529, and 1868, p. 457, etc.); but excite no such sentiment beyond these limits. A North-American Indian is well pleased with himself, and is honoured by others, when he scalps a man of another tribe; and a Dyak cuts off the head of an unoffending person, and dries it as a trophy. The murder of infants has prevailed on the largest scale throughout the world (32. The fullest account which I have met with is by Dr. Gerland, in his 'Ueber den Aussterben der Naturvölker,' 1868; but I shall have to recur to the subject of infanticide in a future chapter.), and has met with no reproach; but infanticide, especially of females, has been thought to be good for the tribe, or at least not injurious. Suicide during former times was not generally considered as a crime (33. See the very interesting discussion on suicide in Lecky's 'History of European Morals,' vol. i. 1869, p. 223. With respect to savages, Mr. Winwood Reade informs me that the negroes of West Africa often commit suicide. It is well known how common it was amongst the miserable aborigines of South America after the Spanish conquest. For New Zealand, see the voyage of the Novara, and for the Aleutian Islands, Müller, as quoted by Houzeau, 'Les Facultés Mentales,' etc., tom. ii. p. 136.), but rather, from the courage displayed, as an honourable act; and it is still practised by some semi-civilised and savage nations without reproach, for it does not obviously concern others of the tribe. It has been recorded that an Indian Thug conscientiously regretted that he had not robbed and strangled as many travellers as did his father before him. In a rude state of civilisation the robbery of strangers is, indeed, generally considered as honourable. Slavery, although in some ways beneficial during ancient times (34. See Mr. Bagehot, 'Physics and Politics,' 1872, p. 72.), is a great crime; yet it was not so regarded until quite recently, even by the most civilised nations. And this was especially the case, because the slaves belonged in general to a race different from that of their masters. As barbarians do not regard the opinion of their women, wives are commonly treated like slaves. Most savages are utterly indifferent to the sufferings of strangers, or even delight in witnessing them. It is well known that the women and children of the North-American Indians aided in torturing their enemies. Some savages take a horrid pleasure in cruelty to animals (35. See, for instance, Mr. Hamilton's account of the Kaffirs, 'Anthropological Review,' 1870, p. xv.), and humanity is an unknown virtue. Nevertheless, besides the family affections, kindness is common, especially during sickness, between the members of the same tribe, and is sometimes extended beyond these limits. Mungo Park's touching account of the kindness of the negro women of the interior to him is well known. Many instances could be given of the noble fidelity of savages towards each other, but not to strangers; common experience justifies the maxim of the Spaniard, "Never, never trust an Indian." There cannot be fidelity without truth; and this fundamental virtue is not rare between the members of the same tribe: thus Mungo Park heard the negro women teaching their young children to love the truth. This, again, is one of the virtues which becomes so deeply rooted in the mind, that it is sometimes practised by savages, even at a high cost, towards strangers; but to lie to your enemy has rarely been thought a sin, as the history of modern diplomacy too plainly shews. As soon as a tribe has a recognised leader, disobedience becomes a crime, and even abject submission is looked at as a sacred virtue. As during rude times no man can be useful or faithful to his tribe without courage, this quality has universally been placed in the highest rank; and although in civilised countries a good yet timid man may be far more useful to the community than a brave one, we cannot help instinctively honouring the latter above a coward, however benevolent. Prudence, on the other hand, which does not concern the welfare of others, though a very useful virtue, has never been highly esteemed. As no man can practise the virtues necessary for the welfare of his tribe without self-sacrifice, self-command, and the power of endurance, these qualities have been at all times highly and most justly valued. The American savage voluntarily submits to the most horrid tortures without a groan, to prove and strengthen his fortitude and courage; and we cannot help admiring him, or even an Indian Fakir, who, from a foolish religious motive, swings suspended by a hook buried in his flesh. The other so-called self-regarding virtues, which do not obviously, though they may really, affect the welfare of the tribe, have never been esteemed by savages, though now highly appreciated by civilised nations. The greatest intemperance is no reproach with savages. Utter licentiousness, and unnatural crimes, prevail to an astounding extent. (36. Mr. M'Lennan has given ('Primitive Marriage,' 1865, p. 176) a good collection of facts on this head.) As soon, however, as marriage, whether polygamous, or monogamous, becomes common, jealousy will lead to the inculcation of female virtue; and this, being honoured, will tend to spread to the unmarried females. How slowly it spreads to the male sex, we see at the present day. Chastity eminently requires self-command; therefore it has been honoured from a very early period in the moral history of civilised man. As a consequence of this, the senseless practice of celibacy has been ranked from a remote period as a virtue. (38. Lecky, 'History of European Morals,' vol. i. 1869, p. 109.) The hatred of indecency, which appears to us so natural as to be thought innate, and which is so valuable an aid to chastity, is a modern virtue, appertaining exclusively, as Sir G. Staunton remarks (38. 'Embassy to China,' vol. ii. p. 348.), to civilised life. This is shewn by the ancient religious rites of various nations, by the drawings on the walls of Pompeii, and by the practices of many savages. We have now seen that actions are regarded by savages, and were probably so regarded by primeval man, as good or bad, solely as they obviously affect the welfare of the tribe,--not that of the species, nor that of an individual member of the tribe. This conclusion agrees well with the belief that the so-called moral sense is aboriginally derived from the social instincts, for both relate at first exclusively to the community. The chief causes of the low morality of savages, as judged by our standard, are, firstly, the confinement of sympathy to the same tribe. Secondly, powers of reasoning insufficient to recognise the bearing of many virtues, especially of the self-regarding virtues, on the general welfare of the tribe. Savages, for instance, fail to trace the multiplied evils consequent on a want of temperance, chastity, etc. And, thirdly, weak power of self-command; for this power has not been strengthened through long-continued, perhaps inherited, habit, instruction and religion. I have entered into the above details on the immorality of savages (39. See on this subject copious evidence in Chap. vii. of Sir J. Lubbock, 'Origin of Civilisation,' 1870.), because some authors have recently taken a high view of their moral nature, or have attributed most of their crimes to mistaken benevolence. (40. For instance Lecky, 'History of European Morals,' vol. i. p. 124.) These authors appear to rest their conclusion on savages possessing those virtues which are serviceable, or even necessary, for the existence of the family and of the tribe,--qualities which they undoubtedly do possess, and often in a high degree. CONCLUDING REMARKS. It was assumed formerly by philosophers of the derivative (41. This term is used in an able article in the 'Westminster Review,' Oct. 1869, p. 498. For the "Greatest happiness principle," see J.S. Mill, 'Utilitarianism,' p. 17.) school of morals that the foundation of morality lay in a form of Selfishness; but more recently the "Greatest happiness principle" has been brought prominently forward. It is, however, more correct to speak of the latter principle as the standard, and not as the motive of conduct. Nevertheless, all the authors whose works I have consulted, with a few exceptions (42. Mill recognises ('System of Logic,' vol. ii. p. 422) in the clearest manner, that actions may be performed through habit without the anticipation of pleasure. Mr. H. Sidgwick also, in his Essay on Pleasure and Desire ('The Contemporary Review,' April 1872, p. 671), remarks: "To sum up, in contravention of the doctrine that our conscious active impulses are always directed towards the production of agreeable sensations in ourselves, I would maintain that we find everywhere in consciousness extra-regarding impulse, directed towards something that is not pleasure; that in many cases the impulse is so far incompatible with the self-regarding that the two do not easily co-exist in the same moment of consciousness." A dim feeling that our impulses do not by any means always arise from any contemporaneous or anticipated pleasure, has, I cannot but think, been one chief cause of the acceptance of the intuitive theory of morality, and of the rejection of the utilitarian or "Greatest happiness" theory. With respect to the latter theory the standard and the motive of conduct have no doubt often been confused, but they are really in some degree blended.), write as if there must be a distinct motive for every action, and that this must be associated with some pleasure or displeasure. But man seems often to act impulsively, that is from instinct or long habit, without any consciousness of pleasure, in the same manner as does probably a bee or ant, when it blindly follows its instincts. Under circumstances of extreme peril, as during a fire, when a man endeavours to save a fellow-creature without a moment's hesitation, he can hardly feel pleasure; and still less has he time to reflect on the dissatisfaction which he might subsequently experience if he did not make the attempt. Should he afterwards reflect over his own conduct, he would feel that there lies within him an impulsive power widely different from a search after pleasure or happiness; and this seems to be the deeply planted social instinct. In the case of the lower animals it seems much more appropriate to speak of their social instincts, as having been developed for the general good rather than for the general happiness of the species. The term, general good, may be defined as the rearing of the greatest number of individuals in full vigour and health, with all their faculties perfect, under the conditions to which they are subjected. As the social instincts both of man and the lower animals have no doubt been developed by nearly the same steps, it would be advisable, if found practicable, to use the same definition in both cases, and to take as the standard of morality, the general good or welfare of the community, rather than the general happiness; but this definition would perhaps require some limitation on account of political ethics. When a man risks his life to save that of a fellow-creature, it seems also more correct to say that he acts for the general good, rather than for the general happiness of mankind. No doubt the welfare and the happiness of the individual usually coincide; and a contented, happy tribe will flourish better than one that is discontented and unhappy. We have seen that even at an early period in the history of man, the expressed wishes of the community will have naturally influenced to a large extent the conduct of each member; and as all wish for happiness, the "greatest happiness principle" will have become a most important secondary guide and object; the social instinct, however, together with sympathy (which leads to our regarding the approbation and disapprobation of others), having served as the primary impulse and guide. Thus the reproach is removed of laying the foundation of the noblest part of our nature in the base principle of selfishness; unless, indeed, the satisfaction which every animal feels, when it follows its proper instincts, and the dissatisfaction felt when prevented, be called selfish. The wishes and opinions of the members of the same community, expressed at first orally, but later by writing also, either form the sole guides of our conduct, or greatly reinforce the social instincts; such opinions, however, have sometimes a tendency directly opposed to these instincts. This latter fact is well exemplified by the LAW OF HONOUR, that is, the law of the opinion of our equals, and not of all our countrymen. The breach of this law, even when the breach is known to be strictly accordant with true morality, has caused many a man more agony than a real crime. We recognise the same influence in the burning sense of shame which most of us have felt, even after the interval of years, when calling to mind some accidental breach of a trifling, though fixed, rule of etiquette. The judgment of the community will generally be guided by some rude experience of what is best in the long run for all the members; but this judgment will not rarely err from ignorance and weak powers of reasoning. Hence the strangest customs and superstitions, in complete opposition to the true welfare and happiness of mankind, have become all-powerful throughout the world. We see this in the horror felt by a Hindoo who breaks his caste, and in many other such cases. It would be difficult to distinguish between the remorse felt by a Hindoo who has yielded to the temptation of eating unclean food, from that felt after committing a theft; but the former would probably be the more severe. How so many absurd rules of conduct, as well as so many absurd religious beliefs, have originated, we do not know; nor how it is that they have become, in all quarters of the world, so deeply impressed on the mind of men; but it is worthy of remark that a belief constantly inculcated during the early years of life, whilst the brain is impressible, appears to acquire almost the nature of an instinct; and the very essence of an instinct is that it is followed independently of reason. Neither can we say why certain admirable virtues, such as the love of truth, are much more highly appreciated by some savage tribes than by others (43. Good instances are given by Mr. Wallace in 'Scientific Opinion,' Sept. 15, 1869; and more fully in his 'Contributions to the Theory of Natural Selection,' 1870, p. 353.); nor, again, why similar differences prevail even amongst highly civilised nations. Knowing how firmly fixed many strange customs and superstitions have become, we need feel no surprise that the self-regarding virtues, supported as they are by reason, should now appear to us so natural as to be thought innate, although they were not valued by man in his early condition. Not withstanding many sources of doubt, man can generally and readily distinguish between the higher and lower moral rules. The higher are founded on the social instincts, and relate to the welfare of others. They are supported by the approbation of our fellow-men and by reason. The lower rules, though some of them when implying self-sacrifice hardly deserve to be called lower, relate chiefly to self, and arise from public opinion, matured by experience and cultivation; for they are not practised by rude tribes. As man advances in civilisation, and small tribes are united into larger communities, the simplest reason would tell each individual that he ought to extend his social instincts and sympathies to all the members of the same nation, though personally unknown to him. This point being once reached, there is only an artificial barrier to prevent his sympathies extending to the men of all nations and races. If, indeed, such men are separated from him by great differences in appearance or habits, experience unfortunately shews us how long it is, before we look at them as our fellow-creatures. Sympathy beyond the confines of man, that is, humanity to the lower animals, seems to be one of the latest moral acquisitions. It is apparently unfelt by savages, except towards their pets. How little the old Romans knew of it is shewn by their abhorrent gladiatorial exhibitions. The very idea of humanity, as far as I could observe, was new to most of the Gauchos of the Pampas. This virtue, one of the noblest with which man is endowed, seems to arise incidentally from our sympathies becoming more tender and more widely diffused, until they are extended to all sentient beings. As soon as this virtue is honoured and practised by some few men, it spreads through instruction and example to the young, and eventually becomes incorporated in public opinion. The highest possible stage in moral culture is when we recognise that we ought to control our thoughts, and "not even in inmost thought to think again the sins that made the past so pleasant to us." (44. Tennyson, Idylls of the King, p. 244.) Whatever makes any bad action familiar to the mind, renders its performance by so much the easier. As Marcus Aurelius long ago said, "Such as are thy habitual thoughts, such also will be the character of thy mind; for the soul is dyed by the thoughts." (45. 'The Thoughts of the Emperor M. Aurelius Antoninus,' English translation, 2nd edit., 1869. p. 112. Marcus Aurelius was born A.D. 121.) Our great philosopher, Herbert Spencer, has recently explained his views on the moral sense. He says (46. Letter to Mr. Mill in Bain's 'Mental and Moral Science,' 1868, p. 722.), "I believe that the experiences of utility organised and consolidated through all past generations of the human race, have been producing corresponding modifications, which, by continued transmission and accumulation, have become in us certain faculties of moral intuition--certain emotions responding to right and wrong conduct, which have no apparent basis in the individual experiences of utility." There is not the least inherent improbability, as it seems to me, in virtuous tendencies being more or less strongly inherited; for, not to mention the various dispositions and habits transmitted by many of our domestic animals to their offspring, I have heard of authentic cases in which a desire to steal and a tendency to lie appeared to run in families of the upper ranks; and as stealing is a rare crime in the wealthy classes, we can hardly account by accidental coincidence for the tendency occurring in two or three members of the same family. If bad tendencies are transmitted, it is probable that good ones are likewise transmitted. That the state of the body by affecting the brain, has great influence on the moral tendencies is known to most of those who have suffered from chronic derangements of the digestion or liver. The same fact is likewise shewn by the "perversion or destruction of the moral sense being often one of the earliest symptoms of mental derangement" (47. Maudsley, 'Body and Mind,' 1870, p. 60.); and insanity is notoriously often inherited. Except through the principle of the transmission of moral tendencies, we cannot understand the differences believed to exist in this respect between the various races of mankind. Even the partial transmission of virtuous tendencies would be an immense assistance to the primary impulse derived directly and indirectly from the social instincts. Admitting for a moment that virtuous tendencies are inherited, it appears probable, at least in such cases as chastity, temperance, humanity to animals, etc., that they become first impressed on the mental organization through habit, instruction and example, continued during several generations in the same family, and in a quite subordinate degree, or not at all, by the individuals possessing such virtues having succeeded best in the struggle for life. My chief source of doubt with respect to any such inheritance, is that senseless customs, superstitions, and tastes, such as the horror of a Hindoo for unclean food, ought on the same principle to be transmitted. I have not met with any evidence in support of the transmission of superstitious customs or senseless habits, although in itself it is perhaps not less probable than that animals should acquire inherited tastes for certain kinds of food or fear of certain foes. Finally the social instincts, which no doubt were acquired by man as by the lower animals for the good of the community, will from the first have given to him some wish to aid his fellows, some feeling of sympathy, and have compelled him to regard their approbation and disapprobation. Such impulses will have served him at a very early period as a rude rule of right and wrong. But as man gradually advanced in intellectual power, and was enabled to trace the more remote consequences of his actions; as he acquired sufficient knowledge to reject baneful customs and superstitions; as he regarded more and more, not only the welfare, but the happiness of his fellow-men; as from habit, following on beneficial experience, instruction and example, his sympathies became more tender and widely diffused, extending to men of all races, to the imbecile, maimed, and other useless members of society, and finally to the lower animals,--so would the standard of his morality rise higher and higher. And it is admitted by moralists of the derivative school and by some intuitionists, that the standard of morality has risen since an early period in the history of man. (48. A writer in the 'North British Review' (July 1869, p. 531), well capable of forming a sound judgment, expresses himself strongly in favour of this conclusion. Mr. Lecky ('History of Morals,' vol. i. p. 143) seems to a certain extent to coincide therein.) As a struggle may sometimes be seen going on between the various instincts of the lower animals, it is not surprising that there should be a struggle in man between his social instincts, with their derived virtues, and his lower, though momentarily stronger impulses or desires. This, as Mr. Galton (49. See his remarkable work on 'Hereditary Genius,' 1869, p. 349. The Duke of Argyll ('Primeval Man,' 1869, p. 188) has some good remarks on the contest in man's nature between right and wrong.) has remarked, is all the less surprising, as man has emerged from a state of barbarism within a comparatively recent period. After having yielded to some temptation we feel a sense of dissatisfaction, shame, repentance, or remorse, analogous to the feelings caused by other powerful instincts or desires, when left unsatisfied or baulked. We compare the weakened impression of a past temptation with the ever present social instincts, or with habits, gained in early youth and strengthened during our whole lives, until they have become almost as strong as instincts. If with the temptation still before us we do not yield, it is because either the social instinct or some custom is at the moment predominant, or because we have learnt that it will appear to us hereafter the stronger, when compared with the weakened impression of the temptation, and we realise that its violation would cause us suffering. Looking to future generations, there is no cause to fear that the social instincts will grow weaker, and we may expect that virtuous habits will grow stronger, becoming perhaps fixed by inheritance. In this case the struggle between our higher and lower impulses will be less severe, and virtue will be triumphant. SUMMARY OF THE LAST TWO CHAPTERS. There can be no doubt that the difference between the mind of the lowest man and that of the highest animal is immense. An anthropomorphous ape, if he could take a dispassionate view of his own case, would admit that though he could form an artful plan to plunder a garden--though he could use stones for fighting or for breaking open nuts, yet that the thought of fashioning a stone into a tool was quite beyond his scope. Still less, as he would admit, could he follow out a train of metaphysical reasoning, or solve a mathematical problem, or reflect on God, or admire a grand natural scene. Some apes, however, would probably declare that they could and did admire the beauty of the coloured skin and fur of their partners in marriage. They would admit, that though they could make other apes understand by cries some of their perceptions and simpler wants, the notion of expressing definite ideas by definite sounds had never crossed their minds. They might insist that they were ready to aid their fellow-apes of the same troop in many ways, to risk their lives for them, and to take charge of their orphans; but they would be forced to acknowledge that disinterested love for all living creatures, the most noble attribute of man, was quite beyond their comprehension. Nevertheless the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, etc., of which man boasts, may be found in an incipient, or even sometimes in a well-developed condition, in the lower animals. They are also capable of some inherited improvement, as we see in the domestic dog compared with the wolf or jackal. If it could be proved that certain high mental powers, such as the formation of general concepts, self-consciousness, etc., were absolutely peculiar to man, which seems extremely doubtful, it is not improbable that these qualities are merely the incidental results of other highly-advanced intellectual faculties; and these again mainly the result of the continued use of a perfect language. At what age does the new-born infant possess the power of abstraction, or become self-conscious, and reflect on its own existence? We cannot answer; nor can we answer in regard to the ascending organic scale. The half-art, half-instinct of language still bears the stamp of its gradual evolution. The ennobling belief in God is not universal with man; and the belief in spiritual agencies naturally follows from other mental powers. The moral sense perhaps affords the best and highest distinction between man and the lower animals; but I need say nothing on this head, as I have so lately endeavoured to shew that the social instincts,--the prime principle of man's moral constitution (50. 'The Thoughts of Marcus Aurelius,' etc., p. 139.)--with the aid of active intellectual powers and the effects of habit, naturally lead to the golden rule, "As ye would that men should do to you, do ye to them likewise;" and this lies at the foundation of morality. In the next chapter I shall make some few remarks on the probable steps and means by which the several mental and moral faculties of man have been gradually evolved. That such evolution is at least possible, ought not to be denied, for we daily see these faculties developing in every infant; and we may trace a perfect gradation from the mind of an utter idiot, lower than that of an animal low in the scale, to the mind of a Newton. CHAPTER V. ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL AND CIVILISED TIMES. Advancement of the intellectual powers through natural selection--Importance of imitation--Social and moral faculties--Their development within the limits of the same tribe--Natural selection as affecting civilised nations--Evidence that civilised nations were once barbarous. The subjects to be discussed in this chapter are of the highest interest, but are treated by me in an imperfect and fragmentary manner. Mr. Wallace, in an admirable paper before referred to (1. Anthropological Review, May 1864, p. clviii.), argues that man, after he had partially acquired those intellectual and moral faculties which distinguish him from the lower animals, would have been but little liable to bodily modifications through natural selection or any other means. For man is enabled through his mental faculties "to keep with an unchanged body in harmony with the changing universe." He has great power of adapting his habits to new conditions of life. He invents weapons, tools, and various stratagems to procure food and to defend himself. When he migrates into a colder climate he uses clothes, builds sheds, and makes fires; and by the aid of fire cooks food otherwise indigestible. He aids his fellow-men in many ways, and anticipates future events. Even at a remote period he practised some division of labour. The lower animals, on the other hand, must have their bodily structure modified in order to survive under greatly changed conditions. They must be rendered stronger, or acquire more effective teeth or claws, for defence against new enemies; or they must be reduced in size, so as to escape detection and danger. When they migrate into a colder climate, they must become clothed with thicker fur, or have their constitutions altered. If they fail to be thus modified, they will cease to exist. The case, however, is widely different, as Mr. Wallace has with justice insisted, in relation to the intellectual and moral faculties of man. These faculties are variable; and we have every reason to believe that the variations tend to be inherited. Therefore, if they were formerly of high importance to primeval man and to his ape-like progenitors, they would have been perfected or advanced through natural selection. Of the high importance of the intellectual faculties there can be no doubt, for man mainly owes to them his predominant position in the world. We can see, that in the rudest state of society, the individuals who were the most sagacious, who invented and used the best weapons or traps, and who were best able to defend themselves, would rear the greatest number of offspring. The tribes, which included the largest number of men thus endowed, would increase in number and supplant other tribes. Numbers depend primarily on the means of subsistence, and this depends partly on the physical nature of the country, but in a much higher degree on the arts which are there practised. As a tribe increases and is victorious, it is often still further increased by the absorption of other tribes. (2. After a time the members or tribes which are absorbed into another tribe assume, as Sir Henry Maine remarks ('Ancient Law,' 1861, p. 131), that they are the co-descendants of the same ancestors.) The stature and strength of the men of a tribe are likewise of some importance for its success, and these depend in part on the nature and amount of the food which can be obtained. In Europe the men of the Bronze period were supplanted by a race more powerful, and, judging from their sword-handles, with larger hands (3. Morlot, 'Soc. Vaud. Sc. Nat.' 1860, p. 294.); but their success was probably still more due to their superiority in the arts. All that we know about savages, or may infer from their traditions and from old monuments, the history of which is quite forgotten by the present inhabitants, shew that from the remotest times successful tribes have supplanted other tribes. Relics of extinct or forgotten tribes have been discovered throughout the civilised regions of the earth, on the wild plains of America, and on the isolated islands in the Pacific Ocean. At the present day civilised nations are everywhere supplanting barbarous nations, excepting where the climate opposes a deadly barrier; and they succeed mainly, though not exclusively, through their arts, which are the products of the intellect. It is, therefore, highly probable that with mankind the intellectual faculties have been mainly and gradually perfected through natural selection; and this conclusion is sufficient for our purpose. Undoubtedly it would be interesting to trace the development of each separate faculty from the state in which it exists in the lower animals to that in which it exists in man; but neither my ability nor knowledge permits the attempt. It deserves notice that, as soon as the progenitors of man became social (and this probably occurred at a very early period), the principle of imitation, and reason, and experience would have increased, and much modified the intellectual powers in a way, of which we see only traces in the lower animals. Apes are much given to imitation, as are the lowest savages; and the simple fact previously referred to, that after a time no animal can be caught in the same place by the same sort of trap, shews that animals learn by experience, and imitate the caution of others. Now, if some one man in a tribe, more sagacious than the others, invented a new snare or weapon, or other means of attack or defence, the plainest self-interest, without the assistance of much reasoning power, would prompt the other members to imitate him; and all would thus profit. The habitual practice of each new art must likewise in some slight degree strengthen the intellect. If the new invention were an important one, the tribe would increase in number, spread, and supplant other tribes. In a tribe thus rendered more numerous there would always be a rather greater chance of the birth of other superior and inventive members. If such men left children to inherit their mental superiority, the chance of the birth of still more ingenious members would be somewhat better, and in a very small tribe decidedly better. Even if they left no children, the tribe would still include their blood-relations; and it has been ascertained by agriculturists (4. I have given instances in my Variation of Animals under Domestication, vol. ii. p. 196.) that by preserving and breeding from the family of an animal, which when slaughtered was found to be valuable, the desired character has been obtained. Turning now to the social and moral faculties. In order that primeval men, or the ape-like progenitors of man, should become social, they must have acquired the same instinctive feelings, which impel other animals to live in a body; and they no doubt exhibited the same general disposition. They would have felt uneasy when separated from their comrades, for whom they would have felt some degree of love; they would have warned each other of danger, and have given mutual aid in attack or defence. All this implies some degree of sympathy, fidelity, and courage. Such social qualities, the paramount importance of which to the lower animals is disputed by no one, were no doubt acquired by the progenitors of man in a similar manner, namely, through natural selection, aided by inherited habit. When two tribes of primeval man, living in the same country, came into competition, if (other circumstances being equal) the one tribe included a great number of courageous, sympathetic and faithful members, who were always ready to warn each other of danger, to aid and defend each other, this tribe would succeed better and conquer the other. Let it be borne in mind how all-important in the never-ceasing wars of savages, fidelity and courage must be. The advantage which disciplined soldiers have over undisciplined hordes follows chiefly from the confidence which each man feels in his comrades. Obedience, as Mr. Bagehot has well shewn (5. See a remarkable series of articles on 'Physics and Politics,' in the 'Fortnightly Review,' Nov. 1867; April 1, 1868; July 1, 1869, since separately published.), is of the highest value, for any form of government is better than none. Selfish and contentious people will not cohere, and without coherence nothing can be effected. A tribe rich in the above qualities would spread and be victorious over other tribes: but in the course of time it would, judging from all past history, be in its turn overcome by some other tribe still more highly endowed. Thus the social and moral qualities would tend slowly to advance and be diffused throughout the world. But it may be asked, how within the limits of the same tribe did a large number of members first become endowed with these social and moral qualities, and how was the standard of excellence raised? It is extremely doubtful whether the offspring of the more sympathetic and benevolent parents, or of those who were the most faithful to their comrades, would be reared in greater numbers than the children of selfish and treacherous parents belonging to the same tribe. He who was ready to sacrifice his life, as many a savage has been, rather than betray his comrades, would often leave no offspring to inherit his noble nature. The bravest men, who were always willing to come to the front in war, and who freely risked their lives for others, would on an average perish in larger numbers than other men. Therefore, it hardly seems probable, that the number of men gifted with such virtues, or that the standard of their excellence, could be increased through natural selection, that is, by the survival of the fittest; for we are not here speaking of one tribe being victorious over another. Although the circumstances, leading to an increase in the number of those thus endowed within the same tribe, are too complex to be clearly followed out, we can trace some of the probable steps. In the first place, as the reasoning powers and foresight of the members became improved, each man would soon learn that if he aided his fellow-men, he would commonly receive aid in return. From this low motive he might acquire the habit of aiding his fellows; and the habit of performing benevolent actions certainly strengthens the feeling of sympathy which gives the first impulse to benevolent actions. Habits, moreover, followed during many generations probably tend to be inherited. But another and much more powerful stimulus to the development of the social virtues, is afforded by the praise and the blame of our fellow-men. To the instinct of sympathy, as we have already seen, it is primarily due, that we habitually bestow both praise and blame on others, whilst we love the former and dread the latter when applied to ourselves; and this instinct no doubt was originally acquired, like all the other social instincts, through natural selection. At how early a period the progenitors of man in the course of their development, became capable of feeling and being impelled by, the praise or blame of their fellow-creatures, we cannot of course say. But it appears that even dogs appreciate encouragement, praise, and blame. The rudest savages feel the sentiment of glory, as they clearly shew by preserving the trophies of their prowess, by their habit of excessive boasting, and even by the extreme care which they take of their personal appearance and decorations; for unless they regarded the opinion of their comrades, such habits would be senseless. They certainly feel shame at the breach of some of their lesser rules, and apparently remorse, as shewn by the case of the Australian who grew thin and could not rest from having delayed to murder some other woman, so as to propitiate his dead wife's spirit. Though I have not met with any other recorded case, it is scarcely credible that a savage, who will sacrifice his life rather than betray his tribe, or one who will deliver himself up as a prisoner rather than break his parole (6. Mr. Wallace gives cases in his 'Contributions to the Theory of Natural Selection,' 1870, p. 354.), would not feel remorse in his inmost soul, if he had failed in a duty, which he held sacred. We may therefore conclude that primeval man, at a very remote period, was influenced by the praise and blame of his fellows. It is obvious, that the members of the same tribe would approve of conduct which appeared to them to be for the general good, and would reprobate that which appeared evil. To do good unto others--to do unto others as ye would they should do unto you--is the foundation-stone of morality. It is, therefore, hardly possible to exaggerate the importance during rude times of the love of praise and the dread of blame. A man who was not impelled by any deep, instinctive feeling, to sacrifice his life for the good of others, yet was roused to such actions by a sense of glory, would by his example excite the same wish for glory in other men, and would strengthen by exercise the noble feeling of admiration. He might thus do far more good to his tribe than by begetting offspring with a tendency to inherit his own high character. With increased experience and reason, man perceives the more remote consequences of his actions, and the self-regarding virtues, such as temperance, chastity, etc., which during early times are, as we have before seen, utterly disregarded, come to be highly esteemed or even held sacred. I need not, however, repeat what I have said on this head in the fourth chapter. Ultimately our moral sense or conscience becomes a highly complex sentiment--originating in the social instincts, largely guided by the approbation of our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, and confirmed by instruction and habit. It must not be forgotten that although a high standard of morality gives but a slight or no advantage to each individual man and his children over the other men of the same tribe, yet that an increase in the number of well-endowed men and an advancement in the standard of morality will certainly give an immense advantage to one tribe over another. A tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to aid one another, and to sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection. At all times throughout the world tribes have supplanted other tribes; and as morality is one important element in their success, the standard of morality and the number of well-endowed men will thus everywhere tend to rise and increase. It is, however, very difficult to form any judgment why one particular tribe and not another has been successful and has risen in the scale of civilisation. Many savages are in the same condition as when first discovered several centuries ago. As Mr. Bagehot has remarked, we are apt to look at progress as normal in human society; but history refutes this. The ancients did not even entertain the idea, nor do the Oriental nations at the present day. According to another high authority, Sir Henry Maine (7. 'Ancient Law,' 1861, p. 22. For Mr. Bagehot's remarks, 'Fortnightly Review,' April 1, 1868, p. 452.), "the greatest part of mankind has never shewn a particle of desire that its civil institutions should be improved." Progress seems to depend on many concurrent favourable conditions, far too complex to be followed out. But it has often been remarked, that a cool climate, from leading to industry and to the various arts, has been highly favourable thereto. The Esquimaux, pressed by hard necessity, have succeeded in many ingenious inventions, but their climate has been too severe for continued progress. Nomadic habits, whether over wide plains, or through the dense forests of the tropics, or along the shores of the sea, have in every case been highly detrimental. Whilst observing the barbarous inhabitants of Tierra del Fuego, it struck me that the possession of some property, a fixed abode, and the union of many families under a chief, were the indispensable requisites for civilisation. Such habits almost necessitate the cultivation of the ground; and the first steps in cultivation would probably result, as I have elsewhere shewn (8. 'The Variation of Animals and Plants under Domestication,' vol. i. p. 309.), from some such accident as the seeds of a fruit-tree falling on a heap of refuse, and producing an unusually fine variety. The problem, however, of the first advance of savages towards civilisation is at present much too difficult to be solved. NATURAL SELECTION AS AFFECTING CIVILISED NATIONS. I have hitherto only considered the advancement of man from a semi-human condition to that of the modern savage. But some remarks on the action of natural selection on civilised nations may be worth adding. This subject has been ably discussed by Mr. W.R. Greg (9. 'Fraser's Magazine,' Sept. 1868, p. 353. This article seems to have struck many persons, and has given rise to two remarkable essays and a rejoinder in the 'Spectator,' Oct. 3rd and 17th, 1868. It has also been discussed in the 'Quarterly Journal of Science,' 1869, p. 152, and by Mr. Lawson Tait in the 'Dublin Quarterly Journal of Medical Science,' Feb. 1869, and by Mr. E. Ray Lankester in his 'Comparative Longevity,' 1870, p. 128. Similar views appeared previously in the 'Australasian,' July 13, 1867. I have borrowed ideas from several of these writers.), and previously by Mr. Wallace and Mr. Galton. (10. For Mr. Wallace, see 'Anthropological Review,' as before cited. Mr. Galton in 'Macmillan's Magazine,' Aug. 1865, p. 318; also his great work, 'Hereditary Genius,' 1870.) Most of my remarks are taken from these three authors. With savages, the weak in body or mind are soon eliminated; and those that survive commonly exhibit a vigorous state of health. We civilised men, on the other hand, do our utmost to check the process of elimination; we build asylums for the imbecile, the maimed, and the sick; we institute poor-laws; and our medical men exert their utmost skill to save the life of every one to the last moment. There is reason to believe that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox. Thus the weak members of civilised societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. It is surprising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race; but excepting in the case of man himself, hardly any one is so ignorant as to allow his worst animals to breed. The aid which we feel impelled to give to the helpless is mainly an incidental result of the instinct of sympathy, which was originally acquired as part of the social instincts, but subsequently rendered, in the manner previously indicated, more tender and more widely diffused. Nor could we check our sympathy, even at the urging of hard reason, without deterioration in the noblest part of our nature. The surgeon may harden himself whilst performing an operation, for he knows that he is acting for the good of his patient; but if we were intentionally to neglect the weak and helpless, it could only be for a contingent benefit, with an overwhelming present evil. We must therefore bear the undoubtedly bad effects of the weak surviving and propagating their kind; but there appears to be at least one check in steady action, namely that the weaker and inferior members of society do not marry so freely as the sound; and this check might be indefinitely increased by the weak in body or mind refraining from marriage, though this is more to be hoped for than expected. In every country in which a large standing army is kept up, the finest young men are taken by the conscription or are enlisted. They are thus exposed to early death during war, are often tempted into vice, and are prevented from marrying during the prime of life. On the other hand the shorter and feebler men, with poor constitutions, are left at home, and consequently have a much better chance of marrying and propagating their kind. (11. Prof. H. Fick ('Einfluss der Naturwissenschaft auf das Recht,' June 1872) has some good remarks on this head, and on other such points.) Man accumulates property and bequeaths it to his children, so that the children of the rich have an advantage over the poor in the race for success, independently of bodily or mental superiority. On the other hand, the children of parents who are short-lived, and are therefore on an average deficient in health and vigour, come into their property sooner than other children, and will be likely to marry earlier, and leave a larger number of offspring to inherit their inferior constitutions. But the inheritance of property by itself is very far from an evil; for without the accumulation of capital the arts could not progress; and it is chiefly through their power that the civilised races have extended, and are now everywhere extending their range, so as to take the place of the lower races. Nor does the moderate accumulation of wealth interfere with the process of selection. When a poor man becomes moderately rich, his children enter trades or professions in which there is struggle enough, so that the able in body and mind succeed best. The presence of a body of well-instructed men, who have not to labour for their daily bread, is important to a degree which cannot be over-estimated; as all high intellectual work is carried on by them, and on such work, material progress of all kinds mainly depends, not to mention other and higher advantages. No doubt wealth when very great tends to convert men into useless drones, but their number is never large; and some degree of elimination here occurs, for we daily see rich men, who happen to be fools or profligate, squandering away their wealth. Primogeniture with entailed estates is a more direct evil, though it may formerly have been a great advantage by the creation of a dominant class, and any government is better than none. Most eldest sons, though they may be weak in body or mind, marry, whilst the younger sons, however superior in these respects, do not so generally marry. Nor can worthless eldest sons with entailed estates squander their wealth. But here, as elsewhere, the relations of civilised life are so complex that some compensatory checks intervene. The men who are rich through primogeniture are able to select generation after generation the more beautiful and charming women; and these must generally be healthy in body and active in mind. The evil consequences, such as they may be, of the continued preservation of the same line of descent, without any selection, are checked by men of rank always wishing to increase their wealth and power; and this they effect by marrying heiresses. But the daughters of parents who have produced single children, are themselves, as Mr. Galton (12. 'Hereditary Genius,' 1870, pp. 132-140.) has shewn, apt to be sterile; and thus noble families are continually cut off in the direct line, and their wealth flows into some side channel; but unfortunately this channel is not determined by superiority of any kind. Although civilisation thus checks in many ways the action of natural selection, it apparently favours the better development of the body, by means of good food and the freedom from occasional hardships. This may be inferred from civilised men having been found, wherever compared, to be physically stronger than savages. (13. Quatrefages, 'Revue des Cours Scientifiques,' 1867-68, p. 659.) They appear also to have equal powers of endurance, as has been proved in many adventurous expeditions. Even the great luxury of the rich can be but little detrimental; for the expectation of life of our aristocracy, at all ages and of both sexes, is very little inferior to that of healthy English lives in the lower classes. (14. See the fifth and sixth columns, compiled from good authorities, in the table given in Mr. E.R. Lankester's 'Comparative Longevity,' 1870, p. 115.) We will now look to the intellectual faculties. If in each grade of society the members were divided into two equal bodies, the one including the intellectually superior and the other the inferior, there can be little doubt that the former would succeed best in all occupations, and rear a greater number of children. Even in the lowest walks of life, skill and ability must be of some advantage; though in many occupations, owing to the great division of labour, a very small one. Hence in civilised nations there will be some tendency to an increase both in the number and in the standard of the intellectually able. But I do not wish to assert that this tendency may not be more than counterbalanced in other ways, as by the multiplication of the reckless and improvident; but even to such as these, ability must be some advantage. It has often been objected to views like the foregoing, that the most eminent men who have ever lived have left no offspring to inherit their great intellect. Mr. Galton says, "I regret I am unable to solve the simple question whether, and how far, men and women who are prodigies of genius are infertile. I have, however, shewn that men of eminence are by no means so." (15. 'Hereditary Genius,' 1870, p. 330.) Great lawgivers, the founders of beneficent religions, great philosophers and discoverers in science, aid the progress of mankind in a far higher degree by their works than by leaving a numerous progeny. In the case of corporeal structures, it is the selection of the slightly better-endowed and the elimination of the slightly less well-endowed individuals, and not the preservation of strongly-marked and rare anomalies, that leads to the advancement of a species. (16. 'Origin of Species' (fifth edition, 1869), p. 104.) So it will be with the intellectual faculties, since the somewhat abler men in each grade of society succeed rather better than the less able, and consequently increase in number, if not otherwise prevented. When in any nation the standard of intellect and the number of intellectual men have increased, we may expect from the law of the deviation from an average, that prodigies of genius will, as shewn by Mr. Galton, appear somewhat more frequently than before. In regard to the moral qualities, some elimination of the worst dispositions is always in progress even in the most civilised nations. Malefactors are executed, or imprisoned for long periods, so that they cannot freely transmit their bad qualities. Melancholic and insane persons are confined, or commit suicide. Violent and quarrelsome men often come to a bloody end. The restless who will not follow any steady occupation--and this relic of barbarism is a great check to civilisation (17. 'Hereditary Genius,' 1870, p. 347.)--emigrate to newly-settled countries; where they prove useful pioneers. Intemperance is so highly destructive, that the expectation of life of the intemperate, at the age of thirty for instance, is only 13.8 years; whilst for the rural labourers of England at the same age it is 40.59 years. (18. E. Ray Lankester, 'Comparative Longevity,' 1870, p. 115. The table of the intemperate is from Neison's 'Vital Statistics.' In regard to profligacy, see Dr. Farr, 'Influence of Marriage on Mortality,' 'Nat. Assoc. for the Promotion of Social Science,' 1858.) Profligate women bear few children, and profligate men rarely marry; both suffer from disease. In the breeding of domestic animals, the elimination of those individuals, though few in number, which are in any marked manner inferior, is by no means an unimportant element towards success. This especially holds good with injurious characters which tend to reappear through reversion, such as blackness in sheep; and with mankind some of the worst dispositions, which occasionally without any assignable cause make their appearance in families, may perhaps be reversions to a savage state, from which we are not removed by very many generations. This view seems indeed recognised in the common expression that such men are the black sheep of the family. With civilised nations, as far as an advanced standard of morality, and an increased number of fairly good men are concerned, natural selection apparently effects but little; though the fundamental social instincts were originally thus gained. But I have already said enough, whilst treating of the lower races, on the causes which lead to the advance of morality, namely, the approbation of our fellow-men--the strengthening of our sympathies by habit--example and imitation--reason--experience, and even self-interest--instruction during youth, and religious feelings. A most important obstacle in civilised countries to an increase in the number of men of a superior class has been strongly insisted on by Mr. Greg and Mr. Galton (19. 'Fraser's Magazine,' Sept. 1868, p. 353. 'Macmillan's Magazine,' Aug. 1865, p. 318. The Rev. F.W. Farrar ('Fraser's Magazine,' Aug. 1870, p. 264) takes a different view.), namely, the fact that the very poor and reckless, who are often degraded by vice, almost invariably marry early, whilst the careful and frugal, who are generally otherwise virtuous, marry late in life, so that they may be able to support themselves and their children in comfort. Those who marry early produce within a given period not only a greater number of generations, but, as shewn by Dr. Duncan (20. 'On the Laws of the Fertility of Women,' in 'Transactions of the Royal Society,' Edinburgh, vol. xxiv. p. 287; now published separately under the title of 'Fecundity, Fertility, and Sterility,' 1871. See, also, Mr. Galton, 'Hereditary Genius,' pp. 352-357, for observations to the above effect.), they produce many more children. The children, moreover, that are borne by mothers during the prime of life are heavier and larger, and therefore probably more vigorous, than those born at other periods. Thus the reckless, degraded, and often vicious members of society, tend to increase at a quicker rate than the provident and generally virtuous members. Or as Mr. Greg puts the case: "The careless, squalid, unaspiring Irishman multiplies like rabbits: the frugal, foreseeing, self-respecting, ambitious Scot, stern in his morality, spiritual in his faith, sagacious and disciplined in his intelligence, passes his best years in struggle and in celibacy, marries late, and leaves few behind him. Given a land originally peopled by a thousand Saxons and a thousand Celts--and in a dozen generations five-sixths of the population would be Celts, but five-sixths of the property, of the power, of the intellect, would belong to the one-sixth of Saxons that remained. In the eternal 'struggle for existence,' it would be the inferior and LESS favoured race that had prevailed--and prevailed by virtue not of its good qualities but of its faults." There are, however, some checks to this downward tendency. We have seen that the intemperate suffer from a high rate of mortality, and the extremely profligate leave few offspring. The poorest classes crowd into towns, and it has been proved by Dr. Stark from the statistics of ten years in Scotland (21. 'Tenth Annual Report of Births, Deaths, etc., in Scotland,' 1867, p. xxix.), that at all ages the death-rate is higher in towns than in rural districts, "and during the first five years of life the town death-rate is almost exactly double that of the rural districts." As these returns include both the rich and the poor, no doubt more than twice the number of births would be requisite to keep up the number of the very poor inhabitants in the towns, relatively to those in the country. With women, marriage at too early an age is highly injurious; for it has been found in France that, "Twice as many wives under twenty die in the year, as died out of the same number of the unmarried." The mortality, also, of husbands under twenty is "excessively high" (22. These quotations are taken from our highest authority on such questions, namely, Dr. Farr, in his paper 'On the Influence of Marriage on the Mortality of the French People,' read before the Nat. Assoc. for the Promotion of Social Science, 1858.), but what the cause of this may be, seems doubtful. Lastly, if the men who prudently delay marrying until they can bring up their families in comfort, were to select, as they often do, women in the prime of life, the rate of increase in the better class would be only slightly lessened. It was established from an enormous body of statistics, taken during 1853, that the unmarried men throughout France, between the ages of twenty and eighty, die in a much larger proportion than the married: for instance, out of every 1000 unmarried men, between the ages of twenty and thirty, 11.3 annually died, whilst of the married, only 6.5 died. (23. Dr. Farr, ibid. The quotations given below are extracted from the same striking paper.) A similar law was proved to hold good, during the years 1863 and 1864, with the entire population above the age of twenty in Scotland: for instance, out of every 1000 unmarried men, between the ages of twenty and thirty, 14.97 annually died, whilst of the married only 7.24 died, that is less than half. (24. I have taken the mean of the quinquennial means, given in 'The Tenth Annual Report of Births, Deaths, etc., in Scotland,' 1867. The quotation from Dr. Stark is copied from an article in the 'Daily News,' Oct. 17, 1868, which Dr. Farr considers very carefully written.) Dr. Stark remarks on this, "Bachelorhood is more destructive to life than the most unwholesome trades, or than residence in an unwholesome house or district where there has never been the most distant attempt at sanitary improvement." He considers that the lessened mortality is the direct result of "marriage, and the more regular domestic habits which attend that state." He admits, however, that the intemperate, profligate, and criminal classes, whose duration of life is low, do not commonly marry; and it must likewise be admitted that men with a weak constitution, ill health, or any great infirmity in body or mind, will often not wish to marry, or will be rejected. Dr. Stark seems to have come to the conclusion that marriage in itself is a main cause of prolonged life, from finding that aged married men still have a considerable advantage in this respect over the unmarried of the same advanced age; but every one must have known instances of men, who with weak health during youth did not marry, and yet have survived to old age, though remaining weak, and therefore always with a lessened chance of life or of marrying. There is another remarkable circumstance which seems to support Dr. Stark's conclusion, namely, that widows and widowers in France suffer in comparison with the married a very heavy rate of mortality; but Dr. Farr attributes this to the poverty and evil habits consequent on the disruption of the family, and to grief. On the whole we may conclude with Dr. Farr that the lesser mortality of married than of unmarried men, which seems to be a general law, "is mainly due to the constant elimination of imperfect types, and to the skilful selection of the finest individuals out of each successive generation;" the selection relating only to the marriage state, and acting on all corporeal, intellectual, and moral qualities. (25. Dr. Duncan remarks ('Fecundity, Fertility, etc.' 1871, p. 334) on this subject: "At every age the healthy and beautiful go over from the unmarried side to the married, leaving the unmarried columns crowded with the sickly and unfortunate.") We may, therefore, infer that sound and good men who out of prudence remain for a time unmarried, do not suffer a high rate of mortality. If the various checks specified in the two last paragraphs, and perhaps others as yet unknown, do not prevent the reckless, the vicious and otherwise inferior members of society from increasing at a quicker rate than the better class of men, the nation will retrograde, as has too often occurred in the history of the world. We must remember that progress is no invariable rule. It is very difficult to say why one civilised nation rises, becomes more powerful, and spreads more widely, than another; or why the same nation progresses more quickly at one time than at another. We can only say that it depends on an increase in the actual number of the population, on the number of men endowed with high intellectual and moral faculties, as well as on their standard of excellence. Corporeal structure appears to have little influence, except so far as vigour of body leads to vigour of mind. It has been urged by several writers that as high intellectual powers are advantageous to a nation, the old Greeks, who stood some grades higher in intellect than any race that has ever existed (26. See the ingenious and original argument on this subject by Mr. Galton, 'Hereditary Genius,' pp. 340-342.), ought, if the power of natural selection were real, to have risen still higher in the scale, increased in number, and stocked the whole of Europe. Here we have the tacit assumption, so often made with respect to corporeal structures, that there is some innate tendency towards continued development in mind and body. But development of all kinds depends on many concurrent favourable circumstances. Natural selection acts only tentatively. Individuals and races may have acquired certain indisputable advantages, and yet have perished from failing in other characters. The Greeks may have retrograded from a want of coherence between the many small states, from the small size of their whole country, from the practice of slavery, or from extreme sensuality; for they did not succumb until "they were enervated and corrupt to the very core." (27. Mr. Greg, 'Fraser's Magazine,' Sept. 1868, p. 357.) The western nations of Europe, who now so immeasurably surpass their former savage progenitors, and stand at the summit of civilisation, owe little or none of their superiority to direct inheritance from the old Greeks, though they owe much to the written works of that wonderful people. Who can positively say why the Spanish nation, so dominant at one time, has been distanced in the race. The awakening of the nations of Europe from the dark ages is a still more perplexing problem. At that early period, as Mr. Galton has remarked, almost all the men of a gentle nature, those given to meditation or culture of the mind, had no refuge except in the bosom of a Church which demanded celibacy (28. 'Hereditary Genius,' 1870, pp. 357-359. The Rev. F.W. Farrar ('Fraser's Magazine,' Aug. 1870, p. 257) advances arguments on the other side. Sir C. Lyell had already ('Principles of Geology,' vol. ii. 1868, p. 489), in a striking passage called attention to the evil influence of the Holy Inquisition in having, through selection, lowered the general standard of intelligence in Europe.); and this could hardly fail to have had a deteriorating influence on each successive generation. During this same period the Holy Inquisition selected with extreme care the freest and boldest men in order to burn or imprison them. In Spain alone some of the best men--those who doubted and questioned, and without doubting there can be no progress--were eliminated during three centuries at the rate of a thousand a year. The evil which the Catholic Church has thus effected is incalculable, though no doubt counterbalanced to a certain, perhaps to a large, extent in other ways; nevertheless, Europe has progressed at an unparalleled rate. The remarkable success of the English as colonists, compared to other European nations, has been ascribed to their "daring and persistent energy"; a result which is well illustrated by comparing the progress of the Canadians of English and French extraction; but who can say how the English gained their energy? There is apparently much truth in the belief that the wonderful progress of the United States, as well as the character of the people, are the results of natural selection; for the more energetic, restless, and courageous men from all parts of Europe have emigrated during the last ten or twelve generations to that great country, and have there succeeded best. (29. Mr. Galton, 'Macmillan's Magazine,' August 1865, p. 325. See also, 'Nature,' 'On Darwinism and National Life,' Dec. 1869, p. 184.) Looking to the distant future, I do not think that the Rev. Mr. Zincke takes an exaggerated view when he says (30. 'Last Winter in the United States,' 1868, p. 29.): "All other series of events--as that which resulted in the culture of mind in Greece, and that which resulted in the empire of Rome--only appear to have purpose and value when viewed in connection with, or rather as subsidiary to...the great stream of Anglo-Saxon emigration to the west." Obscure as is the problem of the advance of civilisation, we can at least see that a nation which produced during a lengthened period the greatest number of highly intellectual, energetic, brave, patriotic, and benevolent men, would generally prevail over less favoured nations. Natural selection follows from the struggle for existence; and this from a rapid rate of increase. It is impossible not to regret bitterly, but whether wisely is another question, the rate at which man tends to increase; for this leads in barbarous tribes to infanticide and many other evils, and in civilised nations to abject poverty, celibacy, and to the late marriages of the prudent. But as man suffers from the same physical evils as the lower animals, he has no right to expect an immunity from the evils consequent on the struggle for existence. Had he not been subjected during primeval times to natural selection, assuredly he would never have attained to his present rank. Since we see in many parts of the world enormous areas of the most fertile land capable of supporting numerous happy homes, but peopled only by a few wandering savages, it might be argued that the struggle for existence had not been sufficiently severe to force man upwards to his highest standard. Judging from all that we know of man and the lower animals, there has always been sufficient variability in their intellectual and moral faculties, for a steady advance through natural selection. No doubt such advance demands many favourable concurrent circumstances; but it may well be doubted whether the most favourable would have sufficed, had not the rate of increase been rapid, and the consequent struggle for existence extremely severe. It even appears from what we see, for instance, in parts of S. America, that a people which may be called civilised, such as the Spanish settlers, is liable to become indolent and to retrograde, when the conditions of life are very easy. With highly civilised nations continued progress depends in a subordinate degree on natural selection; for such nations do not supplant and exterminate one another as do savage tribes. Nevertheless the more intelligent members within the same community will succeed better in the long run than the inferior, and leave a more numerous progeny, and this is a form of natural selection. The more efficient causes of progress seem to consist of a good education during youth whilst the brain is impressible, and of a high standard of excellence, inculcated by the ablest and best men, embodied in the laws, customs and traditions of the nation, and enforced by public opinion. It should, however, be borne in mind, that the enforcement of public opinion depends on our appreciation of the approbation and disapprobation of others; and this appreciation is founded on our sympathy, which it can hardly be doubted was originally developed through natural selection as one of the most important elements of the social instincts. (31. I am much indebted to Mr. John Morley for some good criticisms on this subject: see, also Broca, 'Les Selections,' 'Revue d'Anthropologie,' 1872.) ON THE EVIDENCE THAT ALL CIVILISED NATIONS WERE ONCE BARBAROUS. The present subject has been treated in so full and admirable a manner by Sir J. Lubbock (32. 'On the Origin of Civilisation,' 'Proceedings of the Ethnological Society,' Nov. 26, 1867.), Mr. Tylor, Mr. M'Lennan, and others, that I need here give only the briefest summary of their results. The arguments recently advanced by the Duke of Argyll (33. 'Primeval Man,' 1869.) and formerly by Archbishop Whately, in favour of the belief that man came into the world as a civilised being, and that all savages have since undergone degradation, seem to me weak in comparison with those advanced on the other side. Many nations, no doubt, have fallen away in civilisation, and some may have lapsed into utter barbarism, though on this latter head I have met with no evidence. The Fuegians were probably compelled by other conquering hordes to settle in their inhospitable country, and they may have become in consequence somewhat more degraded; but it would be difficult to prove that they have fallen much below the Botocudos, who inhabit the finest parts of Brazil. The evidence that all civilised nations are the descendants of barbarians, consists, on the one side, of clear traces of their former low condition in still-existing customs, beliefs, language, etc.; and on the other side, of proofs that savages are independently able to raise themselves a few steps in the scale of civilisation, and have actually thus risen. The evidence on the first head is extremely curious, but cannot be here given: I refer to such cases as that of the art of enumeration, which, as Mr. Tylor clearly shews by reference to the words still used in some places, originated in counting the fingers, first of one hand and then of the other, and lastly of the toes. We have traces of this in our own decimal system, and in the Roman numerals, where, after the V, which is supposed to be an abbreviated picture of a human hand, we pass on to VI, etc., when the other hand no doubt was used. So again, "when we speak of three-score and ten, we are counting by the vigesimal system, each score thus ideally made, standing for 20--for 'one man' as a Mexican or Carib would put it." (34. 'Royal Institution of Great Britain,' March 15, 1867. Also, 'Researches into the Early History of Mankind,' 1865.) According to a large and increasing school of philologists, every language bears the marks of its slow and gradual evolution. So it is with the art of writing, for letters are rudiments of pictorial representations. It is hardly possible to read Mr. M'Lennan's work (35. 'Primitive Marriage,' 1865. See, likewise, an excellent article, evidently by the same author, in the 'North British Review,' July 1869. Also, Mr. L.H. Morgan, 'A Conjectural Solution of the Origin of the Class. System of Relationship,' in 'Proc. American Acad. of Sciences,' vol. vii. Feb. 1868. Prof. Schaaffhausen ('Anthropolog. Review,' Oct. 1869, p. 373) remarks on "the vestiges of human sacrifices found both in Homer and the Old Testament.") and not admit that almost all civilised nations still retain traces of such rude habits as the forcible capture of wives. What ancient nation, as the same author asks, can be named that was originally monogamous? The primitive idea of justice, as shewn by the law of battle and other customs of which vestiges still remain, was likewise most rude. Many existing superstitions are the remnants of former false religious beliefs. The highest form of religion--the grand idea of God hating sin and loving righteousness--was unknown during primeval times. Turning to the other kind of evidence: Sir J. Lubbock has shewn that some savages have recently improved a little in some of their simpler arts. From the extremely curious account which he gives of the weapons, tools, and arts, in use amongst savages in various parts of the world, it cannot be doubted that these have nearly all been independent discoveries, excepting perhaps the art of making fire. (36. Sir J. Lubbock, 'Prehistoric Times,' 2nd edit. 1869, chaps. xv. and xvi. et passim. See also the excellent 9th Chapter in Tylor's 'Early History of Mankind,' 2nd edit., 1870.) The Australian boomerang is a good instance of one such independent discovery. The Tahitians when first visited had advanced in many respects beyond the inhabitants of most of the other Polynesian islands. There are no just grounds for the belief that the high culture of the native Peruvians and Mexicans was derived from abroad (37. Dr. F. Müller has made some good remarks to this effect in the 'Reise der Novara: Anthropolog. Theil,' Abtheil. iii. 1868, s. 127.); many native plants were there cultivated, and a few native animals domesticated. We should bear in mind that, judging from the small influence of most missionaries, a wandering crew from some semi-civilised land, if washed to the shores of America, would not have produced any marked effect on the natives, unless they had already become somewhat advanced. Looking to a very remote period in the history of the world, we find, to use Sir J. Lubbock's well-known terms, a paleolithic and neolithic period; and no one will pretend that the art of grinding rough flint tools was a borrowed one. In all parts of Europe, as far east as Greece, in Palestine, India, Japan, New Zealand, and Africa, including Egypt, flint tools have been discovered in abundance; and of their use the existing inhabitants retain no tradition. There is also indirect evidence of their former use by the Chinese and ancient Jews. Hence there can hardly be a doubt that the inhabitants of these countries, which include nearly the whole civilised world, were once in a barbarous condition. To believe that man was aboriginally civilised and then suffered utter degradation in so many regions, is to take a pitiably low view of human nature. It is apparently a truer and more cheerful view that progress has been much more general than retrogression; that man has risen, though by slow and interrupted steps, from a lowly condition to the highest standard as yet attained by him in knowledge, morals and religion. CHAPTER VI. ON THE AFFINITIES AND GENEALOGY OF MAN. Position of man in the animal series--The natural system genealogical--Adaptive characters of slight value--Various small points of resemblance between man and the Quadrumana--Rank of man in the natural system--Birthplace and antiquity of man--Absence of fossil connecting links--Lower stages in the genealogy of man, as inferred, firstly from his affinities and secondly from his structure--Early androgynous condition of the Vertebrata--Conclusion. Even if it be granted that the difference between man and his nearest allies is as great in corporeal structure as some naturalists maintain, and although we must grant that the difference between them is immense in mental power, yet the facts given in the earlier chapters appear to declare, in the plainest manner, that man is descended from some lower form, notwithstanding that connecting-links have not hitherto been discovered. Man is liable to numerous, slight, and diversified variations, which are induced by the same general causes, are governed and transmitted in accordance with the same general laws, as in the lower animals. Man has multiplied so rapidly, that he has necessarily been exposed to struggle for existence, and consequently to natural selection. He has given rise to many races, some of which differ so much from each other, that they have often been ranked by naturalists as distinct species. His body is constructed on the same homological plan as that of other mammals. He passes through the same phases of embryological development. He retains many rudimentary and useless structures, which no doubt were once serviceable. Characters occasionally make their re-appearance in him, which we have reason to believe were possessed by his early progenitors. If the origin of man had been wholly different from that of all other animals, these various appearances would be mere empty deceptions; but such an admission is incredible. These appearances, on the other hand, are intelligible, at least to a large extent, if man is the co-descendant with other mammals of some unknown and lower form. Some naturalists, from being deeply impressed with the mental and spiritual powers of man, have divided the whole organic world into three kingdoms, the Human, the Animal, and the Vegetable, thus giving to man a separate kingdom. (1. Isidore Geoffroy St.-Hilaire gives a detailed account of the position assigned to man by various naturalists in their classifications: 'Hist. Nat. Gen.' tom. ii. 1859, pp. 170-189.) Spiritual powers cannot be compared or classed by the naturalist: but he may endeavour to shew, as I have done, that the mental faculties of man and the lower animals do not differ in kind, although immensely in degree. A difference in degree, however great, does not justify us in placing man in a distinct kingdom, as will perhaps be best illustrated by comparing the mental powers of two insects, namely, a coccus or scale-insect and an ant, which undoubtedly belong to the same class. The difference is here greater than, though of a somewhat different kind from, that between man and the highest mammal. The female coccus, whilst young, attaches itself by its proboscis to a plant; sucks the sap, but never moves again; is fertilised and lays eggs; and this is its whole history. On the other hand, to describe the habits and mental powers of worker-ants, would require, as Pierre Huber has shewn, a large volume; I may, however, briefly specify a few points. Ants certainly communicate information to each other, and several unite for the same work, or for games of play. They recognise their fellow-ants after months of absence, and feel sympathy for each other. They build great edifices, keep them clean, close the doors in the evening, and post sentries. They make roads as well as tunnels under rivers, and temporary bridges over them, by clinging together. They collect food for the community, and when an object, too large for entrance, is brought to the nest, they enlarge the door, and afterwards build it up again. They store up seeds, of which they prevent the germination, and which, if damp, are brought up to the surface to dry. They keep aphides and other insects as milch-cows. They go out to battle in regular bands, and freely sacrifice their lives for the common weal. They emigrate according to a preconcerted plan. They capture slaves. They move the eggs of their aphides, as well as their own eggs and cocoons, into warm parts of the nest, in order that they may be quickly hatched; and endless similar facts could be given. (2. Some of the most interesting facts ever published on the habits of ants are given by Mr. Belt, in his 'Naturalist in Nicaragua,' 1874. See also Mr. Moggridge's admirable work, 'Harvesting Ants,' etc., 1873, also 'L'Instinct chez les Insectes,' by M. George Pouchet, 'Revue des Deux Mondes,' Feb. 1870, p. 682.) On the whole, the difference in mental power between an ant and a coccus is immense; yet no one has ever dreamed of placing these insects in distinct classes, much less in distinct kingdoms. No doubt the difference is bridged over by other insects; and this is not the case with man and the higher apes. But we have every reason to believe that the breaks in the series are simply the results of many forms having become extinct. Professor Owen, relying chiefly on the structure of the brain, has divided the mammalian series into four sub-classes. One of these he devotes to man; in another he places both the marsupials and the Monotremata; so that he makes man as distinct from all other mammals as are these two latter groups conjoined. This view has not been accepted, as far as I am aware, by any naturalist capable of forming an independent judgment, and therefore need not here be further considered. We can understand why a classification founded on any single character or organ--even an organ so wonderfully complex and important as the brain--or on the high development of the mental faculties, is almost sure to prove unsatisfactory. This principle has indeed been tried with hymenopterous insects; but when thus classed by their habits or instincts, the arrangement proved thoroughly artificial. (3. Westwood, 'Modern Classification of Insects,' vol. ii. 1840, p. 87.) Classifications may, of course, be based on any character whatever, as on size, colour, or the element inhabited; but naturalists have long felt a profound conviction that there is a natural system. This system, it is now generally admitted, must be, as far as possible, genealogical in arrangement,--that is, the co-descendants of the same form must be kept together in one group, apart from the co-descendants of any other form; but if the parent-forms are related, so will be their descendants, and the two groups together will form a larger group. The amount of difference between the several groups--that is the amount of modification which each has undergone--is expressed by such terms as genera, families, orders, and classes. As we have no record of the lines of descent, the pedigree can be discovered only by observing the degrees of resemblance between the beings which are to be classed. For this object numerous points of resemblance are of much more importance than the amount of similarity or dissimilarity in a few points. If two languages were found to resemble each other in a multitude of words and points of construction, they would be universally recognised as having sprung from a common source, notwithstanding that they differed greatly in some few words or points of construction. But with organic beings the points of resemblance must not consist of adaptations to similar habits of life: two animals may, for instance, have had their whole frames modified for living in the water, and yet they will not be brought any nearer to each other in the natural system. Hence we can see how it is that resemblances in several unimportant structures, in useless and rudimentary organs, or not now functionally active, or in an embryological condition, are by far the most serviceable for classification; for they can hardly be due to adaptations within a late period; and thus they reveal the old lines of descent or of true affinity. We can further see why a great amount of modification in some one character ought not to lead us to separate widely any two organisms. A part which already differs much from the same part in other allied forms has already, according to the theory of evolution, varied much; consequently it would (as long as the organism remained exposed to the same exciting conditions) be liable to further variations of the same kind; and these, if beneficial, would be preserved, and thus be continually augmented. In many cases the continued development of a part, for instance, of the beak of a bird, or of the teeth of a mammal, would not aid the species in gaining its food, or for any other object; but with man we can see no definite limit to the continued development of the brain and mental faculties, as far as advantage is concerned. Therefore in determining the position of man in the natural or genealogical system, the extreme development of his brain ought not to outweigh a multitude of resemblances in other less important or quite unimportant points. The greater number of naturalists who have taken into consideration the whole structure of man, including his mental faculties, have followed Blumenbach and Cuvier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the orders of the Quadrumana, Carnivora, etc. Recently many of our best naturalists have recurred to the view first propounded by Linnaeus, so remarkable for his sagacity, and have placed man in the same Order with the Quadrumana, under the title of the Primates. The justice of this conclusion will be admitted: for in the first place, we must bear in mind the comparative insignificance for classification of the great development of the brain in man, and that the strongly-marked differences between the skulls of man and the Quadrumana (lately insisted upon by Bischoff, Aeby, and others) apparently follow from their differently developed brains. In the second place, we must remember that nearly all the other and more important differences between man and the Quadrumana are manifestly adaptive in their nature, and relate chiefly to the erect position of man; such as the structure of his hand, foot, and pelvis, the curvature of his spine, and the position of his head. The family of Seals offers a good illustration of the small importance of adaptive characters for classification. These animals differ from all other Carnivora in the form of their bodies and in the structure of their limbs, far more than does man from the higher apes; yet in most systems, from that of Cuvier to the most recent one by Mr. Flower (4. 'Proceedings Zoological Society,' 1863, p. 4.), seals are ranked as a mere family in the Order of the Carnivora. If man had not been his own classifier, he would never have thought of founding a separate order for his own reception. It would be beyond my limits, and quite beyond my knowledge, even to name the innumerable points of structure in which man agrees with the other Primates. Our great anatomist and philosopher, Prof. Huxley, has fully discussed this subject (5. 'Evidence as to Man's Place in Nature,' 1863, p. 70, et passim.), and concludes that man in all parts of his organization differs less from the higher apes, than these do from the lower members of the same group. Consequently there "is no justification for placing man in a distinct order." In an early part of this work I brought forward various facts, shewing how closely man agrees in constitution with the higher mammals; and this agreement must depend on our close similarity in minute structure and chemical composition. I gave, as instances, our liability to the same diseases, and to the attacks of allied parasites; our tastes in common for the same stimulants, and the similar effects produced by them, as well as by various drugs, and other such facts. As small unimportant points of resemblance between man and the Quadrumana are not commonly noticed in systematic works, and as, when numerous, they clearly reveal our relationship, I will specify a few such points. The relative position of our features is manifestly the same; and the various emotions are displayed by nearly similar movements of the muscles and skin, chiefly above the eyebrows and round the mouth. Some few expressions are, indeed, almost the same, as in the weeping of certain kinds of monkeys and in the laughing noise made by others, during which the corners of the mouth are drawn backwards, and the lower eyelids wrinkled. The external ears are curiously alike. In man the nose is much more prominent than in most monkeys; but we may trace the commencement of an aquiline curvature in the nose of the Hoolock Gibbon; and this in the Semnopithecus nasica is carried to a ridiculous extreme. The faces of many monkeys are ornamented with beards, whiskers, or moustaches. The hair on the head grows to a great length in some species of Semnopithecus (6. Isidore Geoffroy St.-Hilaire, 'Hist. Nat. Gen.' tom. ii. 1859, p. 217.); and in the Bonnet monkey (Macacus radiatus) it radiates from a point on the crown, with a parting down the middle. It is commonly said that the forehead gives to man his noble and intellectual appearance; but the thick hair on the head of the Bonnet monkey terminates downwards abruptly, and is succeeded by hair so short and fine that at a little distance the forehead, with the exception of the eyebrows, appears quite naked. It has been erroneously asserted that eyebrows are not present in any monkey. In the species just named the degree of nakedness of the forehead differs in different individuals; and Eschricht states (7. '�ber die Richtung der Haare,' etc., Müller's 'Archiv fur Anat. und Phys.' 1837, s. 51.) that in our children the limit between the hairy scalp and the naked forehead is sometimes not well defined; so that here we seem to have a trifling case of reversion to a progenitor, in whom the forehead had not as yet become quite naked. It is well known that the hair on our arms tends to converge from above and below to a point at the elbow. This curious arrangement, so unlike that in most of the lower mammals, is common to the gorilla, chimpanzee, orang, some species of Hylobates, and even to some few American monkeys. But in Hylobates agilis the hair on the fore-arm is directed downwards or towards the wrist in the ordinary manner; and in H. lar it is nearly erect, with only a very slight forward inclination; so that in this latter species it is in a transitional state. It can hardly be doubted that with most mammals the thickness of the hair on the back and its direction, is adapted to throw off the rain; even the transverse hairs on the fore-legs of a dog may serve for this end when he is coiled up asleep. Mr. Wallace, who has carefully studied the habits of the orang, remarks that the convergence of the hair towards the elbow on the arms of the orang may be explained as serving to throw off the rain, for this animal during rainy weather sits with its arms bent, and with the hands clasped round a branch or over its head. According to Livingstone, the gorilla also "sits in pelting rain with his hands over his head." (8. Quoted by Reade, 'The African Sketch Book,' vol i. 1873, p. 152.) If the above explanation is correct, as seems probable, the direction of the hair on our own arms offers a curious record of our former state; for no one supposes that it is now of any use in throwing off the rain; nor, in our present erect condition, is it properly directed for this purpose. It would, however, be rash to trust too much to the principle of adaptation in regard to the direction of the hair in man or his early progenitors; for it is impossible to study the figures given by Eschricht of the arrangement of the hair on the human foetus (this being the same as in the adult) and not agree with this excellent observer that other and more complex causes have intervened. The points of convergence seem to stand in some relation to those points in the embryo which are last closed in during development. There appears, also, to exist some relation between the arrangement of the hair on the limbs, and the course of the medullary arteries. (9. On the hair in Hylobates, see 'Natural History of Mammals,' by C.L. Martin, 1841, p. 415. Also, Isidore Geoffroy on the American monkeys and other kinds, 'Hist. Nat. Gen.' vol. ii. 1859, pp. 216, 243. Eschricht, ibid. s. 46, 55, 61. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 619. Wallace, 'Contributions to the Theory of Natural Selection,' 1870, p. 344.) It must not be supposed that the resemblances between man and certain apes in the above and in many other points--such as in having a naked forehead, long tresses on the head, etc.,--are all necessarily the result of unbroken inheritance from a common progenitor, or of subsequent reversion. Many of these resemblances are more probably due to analogous variation, which follows, as I have elsewhere attempted to shew (10. 'Origin of Species,' 5th edit. 1869, p.194. 'The Variation of Animals and Plants under Domestication,' vol. ii. 1868, p. 348.), from co-descended organisms having a similar constitution, and having been acted on by like causes inducing similar modifications. With respect to the similar direction of the hair on the fore-arms of man and certain monkeys, as this character is common to almost all the anthropomorphous apes, it may probably be attributed to inheritance; but this is not certain, as some very distinct American monkeys are thus characterised. Although, as we have now seen, man has no just right to form a separate Order for his own reception, he may perhaps claim a distinct Sub-order or Family. Prof. Huxley, in his last work (11. 'An Introduction to the Classification of Animals,' 1869, p. 99.), divides the primates into three Sub-orders; namely, the Anthropidae with man alone, the Simiadae including monkeys of all kinds, and the Lemuridae with the diversified genera of lemurs. As far as differences in certain important points of structure are concerned, man may no doubt rightly claim the rank of a Sub-order; and this rank is too low, if we look chiefly to his mental faculties. Nevertheless, from a genealogical point of view it appears that this rank is too high, and that man ought to form merely a Family, or possibly even only a Sub-family. If we imagine three lines of descent proceeding from a common stock, it is quite conceivable that two of them might after the lapse of ages be so slightly changed as still to remain as species of the same genus, whilst the third line might become so greatly modified as to deserve to rank as a distinct Sub-family, Family, or even Order. But in this case it is almost certain that the third line would still retain through inheritance numerous small points of resemblance with the other two. Here, then, would occur the difficulty, at present insoluble, how much weight we ought to assign in our classifications to strongly-marked differences in some few points,--that is, to the amount of modification undergone; and how much to close resemblance in numerous unimportant points, as indicating the lines of descent or genealogy. To attach much weight to the few but strong differences is the most obvious and perhaps the safest course, though it appears more correct to pay great attention to the many small resemblances, as giving a truly natural classification. In forming a judgment on this head with reference to man, we must glance at the classification of the Simiadae. This family is divided by almost all naturalists into the Catarrhine group, or Old World monkeys, all of which are characterised (as their name expresses) by the peculiar structure of their nostrils, and by having four premolars in each jaw; and into the Platyrrhine group or New World monkeys (including two very distinct sub-groups), all of which are characterised by differently constructed nostrils, and by having six premolars in each jaw. Some other small differences might be mentioned. Now man unquestionably belongs in his dentition, in the structure of his nostrils, and some other respects, to the Catarrhine or Old World division; nor does he resemble the Platyrrhines more closely than the Catarrhines in any characters, excepting in a few of not much importance and apparently of an adaptive nature. It is therefore against all probability that some New World species should have formerly varied and produced a man-like creature, with all the distinctive characters proper to the Old World division; losing at the same time all its own distinctive characters. There can, consequently, hardly be a doubt that man is an off-shoot from the Old World Simian stem; and that under a genealogical point of view he must be classed with the Catarrhine division. (12. This is nearly the same classification as that provisionally adopted by Mr. St. George Mivart, ('Transactions, Philosophical Society," 1867, p. 300), who, after separating the Lemuridae, divides the remainder of the Primates into the Hominidae, the Simiadae which answer to the Catarrhines, the Cebidae, and the Hapalidae,--these two latter groups answering to the Platyrrhines. Mr. Mivart still abides by the same view; see 'Nature,' 1871, p. 481.) The anthropomorphous apes, namely the gorilla, chimpanzee, orang, and hylobates, are by most naturalists separated from the other Old World monkeys, as a distinct sub-group. I am aware that Gratiolet, relying on the structure of the brain, does not admit the existence of this sub-group, and no doubt it is a broken one. Thus the orang, as Mr. St. G. Mivart remarks, "is one of the most peculiar and aberrant forms to be found in the Order." (13. 'Transactions, Zoolog. Soc.' vol. vi. 1867, p. 214.) The remaining non-anthropomorphous Old World monkeys, are again divided by some naturalists into two or three smaller sub-groups; the genus Semnopithecus, with its peculiar sacculated stomach, being the type of one sub-group. But it appears from M. Gaudry's wonderful discoveries in Attica, that during the Miocene period a form existed there, which connected Semnopithecus and Macacus; and this probably illustrates the manner in which the other and higher groups were once blended together. If the anthropomorphous apes be admitted to form a natural sub-group, then as man agrees with them, not only in all those characters which he possesses in common with the whole Catarrhine group, but in other peculiar characters, such as the absence of a tail and of callosities, and in general appearance, we may infer that some ancient member of the anthropomorphous sub-group gave birth to man. It is not probable that, through the law of analogous variation, a member of one of the other lower sub-groups should have given rise to a man-like creature, resembling the higher anthropomorphous apes in so many respects. No doubt man, in comparison with most of his allies, has undergone an extraordinary amount of modification, chiefly in consequence of the great development of his brain and his erect position; nevertheless, we should bear in mind that he "is but one of several exceptional forms of Primates." (14. Mr. St. G. Mivart, 'Transactions of the Philosophical Society,' 1867, p. 410.) Every naturalist, who believes in the principle of evolution, will grant that the two main divisions of the Simiadae, namely the Catarrhine and Platyrrhine monkeys, with their sub-groups, have all proceeded from some one extremely ancient progenitor. The early descendants of this progenitor, before they had diverged to any considerable extent from each other, would still have formed a single natural group; but some of the species or incipient genera would have already begun to indicate by their diverging characters the future distinctive marks of the Catarrhine and Platyrrhine divisions. Hence the members of this supposed ancient group would not have been so uniform in their dentition, or in the structure of their nostrils, as are the existing Catarrhine monkeys in one way and the Platyrrhines in another way, but would have resembled in this respect the allied Lemuridae, which differ greatly from each other in the form of their muzzles (15. Messrs. Murie and Mivart on the Lemuroidea, 'Transactions, Zoological Society,' vol. vii, 1869, p. 5.), and to an extraordinary degree in their dentition. The Catarrhine and Platyrrhine monkeys agree in a multitude of characters, as is shewn by their unquestionably belonging to one and the same Order. The many characters which they possess in common can hardly have been independently acquired by so many distinct species; so that these characters must have been inherited. But a naturalist would undoubtedly have ranked as an ape or a monkey, an ancient form which possessed many characters common to the Catarrhine and Platyrrhine monkeys, other characters in an intermediate condition, and some few, perhaps, distinct from those now found in either group. And as man from a genealogical point of view belongs to the Catarrhine or Old World stock, we must conclude, however much the conclusion may revolt our pride, that our early progenitors would have been properly thus designated. (16. Haeckel has come to this same conclusion. See '�ber die Entstehung des Menschengeschlechts,' in Virchow's 'Sammlung. gemein. wissen. Vorträge,' 1868, s. 61. Also his 'Natürliche Schöpfungsgeschichte,' 1868, in which he gives in detail his views on the genealogy of man.) But we must not fall into the error of supposing that the early progenitor of the whole Simian stock, including man, was identical with, or even closely resembled, any existing ape or monkey. ON THE BIRTHPLACE AND ANTIQUITY OF MAN. We are naturally led to enquire, where was the birthplace of man at that stage of descent when our progenitors diverged from the Catarrhine stock? The fact that they belonged to this stock clearly shews that they inhabited the Old World; but not Australia nor any oceanic island, as we may infer from the laws of geographical distribution. In each great region of the world the living mammals are closely related to the extinct species of the same region. It is therefore probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man's nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere. But it is useless to speculate on this subject; for two or three anthropomorphous apes, one the Dryopithecus (17. Dr. C. Forsyth Major, 'Sur les Singes fossiles trouvés en Italie:' 'Soc. Ital. des Sc. Nat.' tom. xv. 1872.) of Lartet, nearly as large as a man, and closely allied to Hylobates, existed in Europe during the Miocene age; and since so remote a period the earth has certainly undergone many great revolutions, and there has been ample time for migration on the largest scale. At the period and place, whenever and wherever it was, when man first lost his hairy covering, he probably inhabited a hot country; a circumstance favourable for the frugiferous diet on which, judging from analogy, he subsisted. We are far from knowing how long ago it was when man first diverged from the Catarrhine stock; but it may have occurred at an epoch as remote as the Eocene period; for that the higher apes had diverged from the lower apes as early as the Upper Miocene period is shewn by the existence of the Dryopithecus. We are also quite ignorant at how rapid a rate organisms, whether high or low in the scale, may be modified under favourable circumstances; we know, however, that some have retained the same form during an enormous lapse of time. From what we see going on under domestication, we learn that some of the co-descendants of the same species may be not at all, some a little, and some greatly changed, all within the same period. Thus it may have been with man, who has undergone a great amount of modification in certain characters in comparison with the higher apes. The great break in the organic chain between man and his nearest allies, which cannot be bridged over by any extinct or living species, has often been advanced as a grave objection to the belief that man is descended from some lower form; but this objection will not appear of much weight to those who, from general reasons, believe in the general principle of evolution. Breaks often occur in all parts of the series, some being wide, sharp and defined, others less so in various degrees; as between the orang and its nearest allies--between the Tarsius and the other Lemuridae--between the elephant, and in a more striking manner between the Ornithorhynchus or Echidna, and all other mammals. But these breaks depend merely on the number of related forms which have become extinct. At some future period, not very distant as measured by centuries, the civilised races of man will almost certainly exterminate, and replace, the savage races throughout the world. At the same time the anthropomorphous apes, as Professor Schaaffhausen has remarked (18. 'Anthropological Review,' April 1867, p. 236.), will no doubt be exterminated. The break between man and his nearest allies will then be wider, for it will intervene between man in a more civilised state, as we may hope, even than the Caucasian, and some ape as low as a baboon, instead of as now between the negro or Australian and the gorilla. With respect to the absence of fossil remains, serving to connect man with his ape-like progenitors, no one will lay much stress on this fact who reads Sir C. Lyell's discussion (19. 'Elements of Geology,' 1865, pp. 583-585. 'Antiquity of Man,' 1863, p. 145.), where he shews that in all the vertebrate classes the discovery of fossil remains has been a very slow and fortuitous process. Nor should it be forgotten that those regions which are the most likely to afford remains connecting man with some extinct ape-like creature, have not as yet been searched by geologists. LOWER STAGES IN THE GENEALOGY OF MAN. We have seen that man appears to have diverged from the Catarrhine or Old World division of the Simiadae, after these had diverged from the New World division. We will now endeavour to follow the remote traces of his genealogy, trusting principally to the mutual affinities between the various classes and orders, with some slight reference to the periods, as far as ascertained, of their successive appearance on the earth. The Lemuridae stand below and near to the Simiadae, and constitute a very distinct family of the primates, or, according to Haeckel and others, a distinct Order. This group is diversified and broken to an extraordinary degree, and includes many aberrant forms. It has, therefore, probably suffered much extinction. Most of the remnants survive on islands, such as Madagascar and the Malayan archipelago, where they have not been exposed to so severe a competition as they would have been on well-stocked continents. This group likewise presents many gradations, leading, as Huxley remarks (20. 'Man's Place in Nature,' p. 105.), "insensibly from the crown and summit of the animal creation down to creatures from which there is but a step, as it seems, to the lowest, smallest, and least intelligent of the placental mammalia." From these various considerations it is probable that the Simiadae were originally developed from the progenitors of the existing Lemuridae; and these in their turn from forms standing very low in the mammalian series. The Marsupials stand in many important characters below the placental mammals. They appeared at an earlier geological period, and their range was formerly much more extensive than at present. Hence the Placentata are generally supposed to have been derived from the Implacentata or Marsupials; not, however, from forms closely resembling the existing Marsupials, but from their early progenitors. The Monotremata are plainly allied to the Marsupials, forming a third and still lower division in the great mammalian series. They are represented at the present day solely by the Ornithorhynchus and Echidna; and these two forms may be safely considered as relics of a much larger group, representatives of which have been preserved in Australia through some favourable concurrence of circumstances. The Monotremata are eminently interesting, as leading in several important points of structure towards the class of reptiles. In attempting to trace the genealogy of the Mammalia, and therefore of man, lower down in the series, we become involved in greater and greater obscurity; but as a most capable judge, Mr. Parker, has remarked, we have good reason to believe, that no true bird or reptile intervenes in the direct line of descent. He who wishes to see what ingenuity and knowledge can effect, may consult Prof. Haeckel's works. (21. Elaborate tables are given in his 'Generelle Morphologie' (B. ii. s. cliii. and s. 425); and with more especial reference to man in his 'Natürliche Schöpfungsgeschichte,' 1868. Prof. Huxley, in reviewing this latter work ('The Academy,' 1869, p. 42) says, that he considers the phylum or lines of descent of the Vertebrata to be admirably discussed by Haeckel, although he differs on some points. He expresses, also, his high estimate of the general tenor and spirit of the whole work.) I will content myself with a few general remarks. Every evolutionist will admit that the five great vertebrate classes, namely, mammals, birds, reptiles, amphibians, and fishes, are descended from some one prototype; for they have much in common, especially during their embryonic state. As the class of fishes is the most lowly organised, and appeared before the others, we may conclude that all the members of the vertebrate kingdom are derived from some fishlike animal. The belief that animals so distinct as a monkey, an elephant, a humming-bird, a snake, a frog, and a fish, etc., could all have sprung from the same parents, will appear monstrous to those who have not attended to the recent progress of natural history. For this belief implies the former existence of links binding closely together all these forms, now so utterly unlike. Nevertheless, it is certain that groups of animals have existed, or do now exist, which serve to connect several of the great vertebrate classes more or less closely. We have seen that the Ornithorhynchus graduates towards reptiles; and Prof. Huxley has discovered, and is confirmed by Mr. Cope and others, that the Dinosaurians are in many important characters intermediate between certain reptiles and certain birds--the birds referred to being the ostrich-tribe (itself evidently a widely-diffused remnant of a larger group) and the Archeopteryx, that strange Secondary bird, with a long lizard-like tail. Again, according to Prof. Owen (22. 'Palaeontology' 1860, p. 199.), the Ichthyosaurians--great sea-lizards furnished with paddles--present many affinities with fishes, or rather, according to Huxley, with amphibians; a class which, including in its highest division frogs and toads, is plainly allied to the Ganoid fishes. These latter fishes swarmed during the earlier geological periods, and were constructed on what is called a generalised type, that is, they presented diversified affinities with other groups of organisms. The Lepidosiren is also so closely allied to amphibians and fishes, that naturalists long disputed in which of these two classes to rank it; it, and also some few Ganoid fishes, have been preserved from utter extinction by inhabiting rivers, which are harbours of refuge, and are related to the great waters of the ocean in the same way that islands are to continents. Lastly, one single member of the immense and diversified class of fishes, namely, the lancelet or amphioxus, is so different from all other fishes, that Haeckel maintains that it ought to form a distinct class in the vertebrate kingdom. This fish is remarkable for its negative characters; it can hardly be said to possess a brain, vertebral column, or heart, etc.; so that it was classed by the older naturalists amongst the worms. Many years ago Prof. Goodsir perceived that the lancelet presented some affinities with the Ascidians, which are invertebrate, hermaphrodite, marine creatures permanently attached to a support. They hardly appear like animals, and consist of a simple, tough, leathery sack, with two small projecting orifices. They belong to the Mulluscoida of Huxley--a lower division of the great kingdom of the Mollusca; but they have recently been placed by some naturalists amongst the Vermes or worms. Their larvae somewhat resemble tadpoles in shape (23. At the Falkland Islands I had the satisfaction of seeing, in April, 1833, and therefore some years before any other naturalist, the locomotive larvae of a compound Ascidian, closely allied to Synoicum, but apparently generically distinct from it. The tail was about five times as long as the oblong head, and terminated in a very fine filament. It was, as sketched by me under a simple microscope, plainly divided by transverse opaque partitions, which I presume represent the great cells figured by Kovalevsky. At an early stage of development the tail was closely coiled round the head of the larva.), and have the power of swimming freely about. Mr. Kovalevsky (24. 'Memoires de l'Acad. des Sciences de St. Petersbourg,' tom. x. No. 15, 1866.) has lately observed that the larvae of Ascidians are related to the Vertebrata, in their manner of development, in the relative position of the nervous system, and in possessing a structure closely like the chorda dorsalis of vertebrate animals; and in this he has been since confirmed by Prof. Kupffer. M. Kovalevsky writes to me from Naples, that he has now carried these observations yet further, and should his results be well established, the whole will form a discovery of the very greatest value. Thus, if we may rely on embryology, ever the safest guide in classification, it seems that we have at last gained a clue to the source whence the Vertebrata were derived. (25. But I am bound to add that some competent judges dispute this conclusion; for instance, M. Giard, in a series of papers in the 'Archives de Zoologie Experimentale,' for 1872. Nevertheless, this naturalist remarks, p. 281, "L'organisation de la larve ascidienne en dehors de toute hypothèse et de toute théorie, nous montre comment la nature peut produire la disposition fondamentale du type vertébré (l'existence d'une corde dorsale) chez un invertébré par la seule condition vitale de l'adaptation, et cette simple possibilité du passage supprime l'abîme entre les deux sous-règnes, encore bien qu'en ignore par où le passage s'est fait en realité.") We should then be justified in believing that at an extremely remote period a group of animals existed, resembling in many respects the larvae of our present Ascidians, which diverged into two great branches--the one retrograding in development and producing the present class of Ascidians, the other rising to the crown and summit of the animal kingdom by giving birth to the Vertebrata. We have thus far endeavoured rudely to trace the genealogy of the Vertebrata by the aid of their mutual affinities. We will now look to man as he exists; and we shall, I think, be able partially to restore the structure of our early progenitors, during successive periods, but not in due order of time. This can be effected by means of the rudiments which man still retains, by the characters which occasionally make their appearance in him through reversion, and by the aid of the principles of morphology and embryology. The various facts, to which I shall here allude, have been given in the previous chapters. The early progenitors of man must have been once covered with hair, both sexes having beards; their ears were probably pointed, and capable of movement; and their bodies were provided with a tail, having the proper muscles. Their limbs and bodies were also acted on by many muscles which now only occasionally reappear, but are normally present in the Quadrumana. At this or some earlier period, the great artery and nerve of the humerus ran through a supra-condyloid foramen. The intestine gave forth a much larger diverticulum or caecum than that now existing. The foot was then prehensile, judging from the condition of the great toe in the foetus; and our progenitors, no doubt, were arboreal in their habits, and frequented some warm, forest-clad land. The males had great canine teeth, which served them as formidable weapons. At a much earlier period the uterus was double; the excreta were voided through a cloaca; and the eye was protected by a third eyelid or nictitating membrane. At a still earlier period the progenitors of man must have been aquatic in their habits; for morphology plainly tells us that our lungs consist of a modified swim-bladder, which once served as a float. The clefts on the neck in the embryo of man shew where the branchiae once existed. In the lunar or weekly recurrent periods of some of our functions we apparently still retain traces of our primordial birthplace, a shore washed by the tides. At about this same early period the true kidneys were replaced by the corpora wolffiana. The heart existed as a simple pulsating vessel; and the chorda dorsalis took the place of a vertebral column. These early ancestors of man, thus seen in the dim recesses of time, must have been as simply, or even still more simply organised than the lancelet or amphioxus. There is one other point deserving a fuller notice. It has long been known that in the vertebrate kingdom one sex bears rudiments of various accessory parts, appertaining to the reproductive system, which properly belong to the opposite sex; and it has now been ascertained that at a very early embryonic period both sexes possess true male and female glands. Hence some remote progenitor of the whole vertebrate kingdom appears to have been hermaphrodite or androgynous. (26. This is the conclusion of Prof. Gegenbaur, one of the highest authorities in comparative anatomy: see 'Grundzüge der vergleich. Anat.' 1870, s. 876. The result has been arrived at chiefly from the study of the Amphibia; but it appears from the researches of Waldeyer (as quoted in 'Journal of Anat. and Phys.' 1869, p. 161), that the sexual organs of even "the higher vertebrata are, in their early condition, hermaphrodite." Similar views have long been held by some authors, though until recently without a firm basis.) But here we encounter a singular difficulty. In the mammalian class the males possess rudiments of a uterus with the adjacent passage, in their vesiculae prostaticae; they bear also rudiments of mammae, and some male Marsupials have traces of a marsupial sack. (27. The male Thylacinus offers the best instance. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 771.) Other analogous facts could be added. Are we, then, to suppose that some extremely ancient mammal continued androgynous, after it had acquired the chief distinctions of its class, and therefore after it had diverged from the lower classes of the vertebrate kingdom? This seems very improbable, for we have to look to fishes, the lowest of all the classes, to find any still existent androgynous forms. (28. Hermaphroditism has been observed in several species of Serranus, as well as in some other fishes, where it is either normal and symmetrical, or abnormal and unilateral. Dr. Zouteveen has given me references on this subject, more especially to a paper by Prof. Halbertsma, in the 'Transact. of the Dutch Acad. of Sciences,' vol. xvi. Dr. Gunther doubts the fact, but it has now been recorded by too many good observers to be any longer disputed. Dr. M. Lessona writes to me, that he has verified the observations made by Cavolini on Serranus. Prof. Ercolani has recently shewn ('Accad. delle Scienze,' Bologna, Dec. 28, 1871) that eels are androgynous.) That various accessory parts, proper to each sex, are found in a rudimentary condition in the opposite sex, may be explained by such organs having been gradually acquired by the one sex, and then transmitted in a more or less imperfect state to the other. When we treat of sexual selection, we shall meet with innumerable instances of this form of transmission,--as in the case of the spurs, plumes, and brilliant colours, acquired for battle or ornament by male birds, and inherited by the females in an imperfect or rudimentary condition. The possession by male mammals of functionally imperfect mammary organs is, in some respects, especially curious. The Monotremata have the proper milk-secreting glands with orifices, but no nipples; and as these animals stand at the very base of the mammalian series, it is probable that the progenitors of the class also had milk-secreting glands, but no nipples. This conclusion is supported by what is known of their manner of development; for Professor Turner informs me, on the authority of Kolliker and Langer, that in the embryo the mammary glands can be distinctly traced before the nipples are in the least visible; and the development of successive parts in the individual generally represents and accords with the development of successive beings in the same line of descent. The Marsupials differ from the Monotremata by possessing nipples; so that probably these organs were first acquired by the Marsupials, after they had diverged from, and risen above, the Monotremata, and were then transmitted to the placental mammals. (29. Prof. Gegenbaur has shewn ('Jenäische Zeitschrift,' Bd. vii. p. 212) that two distinct types of nipples prevail throughout the several mammalian orders, but that it is quite intelligible how both could have been derived from the nipples of the Marsupials, and the latter from those of the Monotremata. See, also, a memoir by Dr. Max Huss, on the mammary glands, ibid. B. viii. p. 176.) No one will suppose that the marsupials still remained androgynous, after they had approximately acquired their present structure. How then are we to account for male mammals possessing mammae? It is possible that they were first developed in the females and then transferred to the males, but from what follows this is hardly probable. It may be suggested, as another view, that long after the progenitors of the whole mammalian class had ceased to be androgynous, both sexes yielded milk, and thus nourished their young; and in the case of the Marsupials, that both sexes carried their young in marsupial sacks. This will not appear altogether improbable, if we reflect that the males of existing syngnathous fishes receive the eggs of the females in their abdominal pouches, hatch them, and afterwards, as some believe, nourish the young (30. Mr. Lockwood believes (as quoted in 'Quart. Journal of Science,' April 1868, p. 269), from what he has observed of the development of Hippocampus, that the walls of the abdominal pouch of the male in some way afford nourishment. On male fishes hatching the ova in their mouths, see a very interesting paper by Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.' Sept. 15, 1857; also Prof. Turner, in 'Journal of Anatomy and Physiology,' Nov. 1, 1866, p. 78. Dr. Gunther has likewise described similar cases.);--that certain other male fishes hatch the eggs within their mouths or branchial cavities;--that certain male toads take the chaplets of eggs from the females, and wind them round their own thighs, keeping them there until the tadpoles are born;--that certain male birds undertake the whole duty of incubation, and that male pigeons, as well as the females, feed their nestlings with a secretion from their crops. But the above suggestion first occurred to me from mammary glands of male mammals being so much more perfectly developed than the rudiments of the other accessory reproductive parts, which are found in the one sex though proper to the other. The mammary glands and nipples, as they exist in male mammals, can indeed hardly be called rudimentary; they are merely not fully developed, and not functionally active. They are sympathetically affected under the influence of certain diseases, like the same organs in the female. They often secrete a few drops of milk at birth and at puberty: this latter fact occurred in the curious case, before referred to, where a young man possessed two pairs of mammae. In man and some other male mammals these organs have been known occasionally to become so well developed during maturity as to yield a fair supply of milk. Now if we suppose that during a former prolonged period male mammals aided the females in nursing their offspring (31. Mlle. C. Royer has suggested a similar view in her 'Origine de l'homme,' etc., 1870.), and that afterwards from some cause (as from the production of a smaller number of young) the males ceased to give this aid, disuse of the organs during maturity would lead to their becoming inactive; and from two well-known principles of inheritance, this state of inactivity would probably be transmitted to the males at the corresponding age of maturity. But at an earlier age these organs would be left unaffected, so that they would be almost equally well developed in the young of both sexes. CONCLUSION. Von Baer has defined advancement or progress in the organic scale better than any one else, as resting on the amount of differentiation and specialisation of the several parts of a being,--when arrived at maturity, as I should be inclined to add. Now as organisms have become slowly adapted to diversified lines of life by means of natural selection, their parts will have become more and more differentiated and specialised for various functions from the advantage gained by the division of physiological labour. The same part appears often to have been modified first for one purpose, and then long afterwards for some other and quite distinct purpose; and thus all the parts are rendered more and more complex. But each organism still retains the general type of structure of the progenitor from which it was aboriginally derived. In accordance with this view it seems, if we turn to geological evidence, that organisation on the whole has advanced throughout the world by slow and interrupted steps. In the great kingdom of the Vertebrata it has culminated in man. It must not, however, be supposed that groups of organic beings are always supplanted, and disappear as soon as they have given birth to other and more perfect groups. The latter, though victorious over their predecessors, may not have become better adapted for all places in the economy of nature. Some old forms appear to have survived from inhabiting protected sites, where they have not been exposed to very severe competition; and these often aid us in constructing our genealogies, by giving us a fair idea of former and lost populations. But we must not fall into the error of looking at the existing members of any lowly-organised group as perfect representatives of their ancient predecessors. The most ancient progenitors in the kingdom of the Vertebrata, at which we are able to obtain an obscure glance, apparently consisted of a group of marine animals (32. The inhabitants of the seashore must be greatly affected by the tides; animals living either about the MEAN high-water mark, or about the MEAN low-water mark, pass through a complete cycle of tidal changes in a fortnight. Consequently, their food supply will undergo marked changes week by week. The vital functions of such animals, living under these conditions for many generations, can hardly fail to run their course in regular weekly periods. Now it is a mysterious fact that in the higher and now terrestrial Vertebrata, as well as in other classes, many normal and abnormal processes have one or more whole weeks as their periods; this would be rendered intelligible if the Vertebrata are descended from an animal allied to the existing tidal Ascidians. Many instances of such periodic processes might be given, as the gestation of mammals, the duration of fevers, etc. The hatching of eggs affords also a good example, for, according to Mr. Bartlett ('Land and Water,' Jan. 7, 1871), the eggs of the pigeon are hatched in two weeks; those of the fowl in three; those of the duck in four; those of the goose in five; and those of the ostrich in seven weeks. As far as we can judge, a recurrent period, if approximately of the right duration for any process or function, would not, when once gained, be liable to change; consequently it might be thus transmitted through almost any number of generations. But if the function changed, the period would have to change, and would be apt to change almost abruptly by a whole week. This conclusion, if sound, is highly remarkable; for the period of gestation in each mammal, and the hatching of each bird's eggs, and many other vital processes, thus betray to us the primordial birthplace of these animals.), resembling the larvae of existing Ascidians. These animals probably gave rise to a group of fishes, as lowly organised as the lancelet; and from these the Ganoids, and other fishes like the Lepidosiren, must have been developed. From such fish a very small advance would carry us on to the Amphibians. We have seen that birds and reptiles were once intimately connected together; and the Monotremata now connect mammals with reptiles in a slight degree. But no one can at present say by what line of descent the three higher and related classes, namely, mammals, birds, and reptiles, were derived from the two lower vertebrate classes, namely, amphibians and fishes. In the class of mammals the steps are not difficult to conceive which led from the ancient Monotremata to the ancient Marsupials; and from these to the early progenitors of the placental mammals. We may thus ascend to the Lemuridae; and the interval is not very wide from these to the Simiadae. The Simiadae then branched off into two great stems, the New World and Old World monkeys; and from the latter, at a remote period, Man, the wonder and glory of the Universe, proceeded. Thus we have given to man a pedigree of prodigious length, but not, it may be said, of noble quality. The world, it has often been remarked, appears as if it had long been preparing for the advent of man: and this, in one sense is strictly true, for he owes his birth to a long line of progenitors. If any single link in this chain had never existed, man would not have been exactly what he now is. Unless we wilfully close our eyes, we may, with our present knowledge, approximately recognise our parentage; nor need we feel ashamed of it. The most humble organism is something much higher than the inorganic dust under our feet; and no one with an unbiassed mind can study any living creature, however humble, without being struck with enthusiasm at its marvellous structure and properties. CHAPTER VII. ON THE RACES OF MAN. The nature and value of specific characters--Application to the races of man--Arguments in favour of, and opposed to, ranking the so-called races of man as distinct species--Sub-species--Monogenists and polygenists--Convergence of character--Numerous points of resemblance in body and mind between the most distinct races of man--The state of man when he first spread over the earth--Each race not descended from a single pair--The extinction of races--The formation of races--The effects of crossing--Slight influence of the direct action of the conditions of life--Slight or no influence of natural selection--Sexual selection. It is not my intention here to describe the several so-called races of men; but I am about to enquire what is the value of the differences between them under a classificatory point of view, and how they have originated. In determining whether two or more allied forms ought to be ranked as species or varieties, naturalists are practically guided by the following considerations; namely, the amount of difference between them, and whether such differences relate to few or many points of structure, and whether they are of physiological importance; but more especially whether they are constant. Constancy of character is what is chiefly valued and sought for by naturalists. Whenever it can be shewn, or rendered probable, that the forms in question have remained distinct for a long period, this becomes an argument of much weight in favour of treating them as species. Even a slight degree of sterility between any two forms when first crossed, or in their offspring, is generally considered as a decisive test of their specific distinctness; and their continued persistence without blending within the same area, is usually accepted as sufficient evidence, either of some degree of mutual sterility, or in the case of animals of some mutual repugnance to pairing. Independently of fusion from intercrossing, the complete absence, in a well-investigated region, of varieties linking together any two closely-allied forms, is probably the most important of all the criterions of their specific distinctness; and this is a somewhat different consideration from mere constancy of character, for two forms may be highly variable and yet not yield intermediate varieties. Geographical distribution is often brought into play unconsciously and sometimes consciously; so that forms living in two widely separated areas, in which most of the other inhabitants are specifically distinct, are themselves usually looked at as distinct; but in truth this affords no aid in distinguishing geographical races from so-called good or true species. Now let us apply these generally-admitted principles to the races of man, viewing him in the same spirit as a naturalist would any other animal. In regard to the amount of difference between the races, we must make some allowance for our nice powers of discrimination gained by the long habit of observing ourselves. In India, as Elphinstone remarks, although a newly-arrived European cannot at first distinguish the various native races, yet they soon appear to him extremely dissimilar (1. 'History of India,' 1841, vol. i. p. 323. Father Ripa makes exactly the same remark with respect to the Chinese.); and the Hindoo cannot at first perceive any difference between the several European nations. Even the most distinct races of man are much more like each other in form than would at first be supposed; certain negro tribes must be excepted, whilst others, as Dr. Rohlfs writes to me, and as I have myself seen, have Caucasian features. This general similarity is well shewn by the French photographs in the Collection Anthropologique du Museum de Paris of the men belonging to various races, the greater number of which might pass for Europeans, as many persons to whom I have shewn them have remarked. Nevertheless, these men, if seen alive, would undoubtedly appear very distinct, so that we are clearly much influenced in our judgment by the mere colour of the skin and hair, by slight differences in the features, and by expression. There is, however, no doubt that the various races, when carefully compared and measured, differ much from each other,--as in the texture of the hair, the relative proportions of all parts of the body (2. A vast number of measurements of Whites, Blacks, and Indians, are given in the 'Investigations in the Military and Anthropolog. Statistics of American Soldiers,' by B.A. Gould, 1869, pp. 298-358; 'On the capacity of the lungs,' p. 471. See also the numerous and valuable tables, by Dr. Weisbach, from the observations of Dr. Scherzer and Dr. Schwarz, in the 'Reise der Novara: Anthropolog. Theil,' 1867.), the capacity of the lungs, the form and capacity of the skull, and even in the convolutions of the brain. (3. See, for instance, Mr. Marshall's account of the brain of a Bushwoman, in 'Philosophical Transactions,' 1864, p. 519.) But it would be an endless task to specify the numerous points of difference. The races differ also in constitution, in acclimatisation and in liability to certain diseases. Their mental characteristics are likewise very distinct; chiefly as it would appear in their emotional, but partly in their intellectual faculties. Every one who has had the opportunity of comparison, must have been struck with the contrast between the taciturn, even morose, aborigines of S. America and the light-hearted, talkative negroes. There is a nearly similar contrast between the Malays and the Papuans (4. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 178.), who live under the same physical conditions, and are separated from each other only by a narrow space of sea. We will first consider the arguments which may be advanced in favour of classing the races of man as distinct species, and then the arguments on the other side. If a naturalist, who had never before seen a Negro, Hottentot, Australian, or Mongolian, were to compare them, he would at once perceive that they differed in a multitude of characters, some of slight and some of considerable importance. On enquiry he would find that they were adapted to live under widely different climates, and that they differed somewhat in bodily constitution and mental disposition. If he were then told that hundreds of similar specimens could be brought from the same countries, he would assuredly declare that they were as good species as many to which he had been in the habit of affixing specific names. This conclusion would be greatly strengthened as soon as he had ascertained that these forms had all retained the same character for many centuries; and that negroes, apparently identical with existing negroes, had lived at least 4000 years ago. (5. With respect to the figures in the famous Egyptian caves of Abou-Simbel, M. Pouchet says ('The Plurality of the Human Races,' Eng. translat., 1864, p. 50), that he was far from finding recognisable representations of the dozen or more nations which some authors believe that they can recognise. Even some of the most strongly-marked races cannot be identified with that degree of unanimity which might have been expected from what has been written on the subject. Thus Messrs. Nott and Gliddon ('Types of Mankind,' p. 148), state that Rameses II., or the Great, has features superbly European; whereas Knox, another firm believer in the specific distinctness of the races of man ('Races of Man,' 1850, p. 201), speaking of young Memnon (the same as Rameses II., as I am informed by Mr. Birch), insists in the strongest manner that he is identical in character with the Jews of Antwerp. Again, when I looked at the statue of Amunoph III., I agreed with two officers of the establishment, both competent judges, that he had a strongly-marked negro type of features; but Messrs. Nott and Gliddon (ibid. p. 146, fig. 53), describe him as a hybrid, but not of "negro intermixture.") He would also hear, on the authority of an excellent observer, Dr. Lund (6. As quoted by Nott and Gliddon, 'Types of Mankind,' 1854, p. 439. They give also corroborative evidence; but C. Vogt thinks that the subject requires further investigation.), that the human skulls found in the caves of Brazil, entombed with many extinct mammals, belonged to the same type as that now prevailing throughout the American Continent. Our naturalist would then perhaps turn to geographical distribution, and he would probably declare that those forms must be distinct species, which differ not only in appearance, but are fitted for hot, as well as damp or dry countries, and for the Arctic regions. He might appeal to the fact that no species in the group next to man--namely, the Quadrumana, can resist a low temperature, or any considerable change of climate; and that the species which come nearest to man have never been reared to maturity, even under the temperate climate of Europe. He would be deeply impressed with the fact, first noticed by Agassiz (7. 'Diversity of Origin of the Human Races,' in the 'Christian Examiner,' July 1850.), that the different races of man are distributed over the world in the same zoological provinces, as those inhabited by undoubtedly distinct species and genera of mammals. This is manifestly the case with the Australian, Mongolian, and Negro races of man; in a less well-marked manner with the Hottentots; but plainly with the Papuans and Malays, who are separated, as Mr. Wallace has shewn, by nearly the same line which divides the great Malayan and Australian zoological provinces. The Aborigines of America range throughout the Continent; and this at first appears opposed to the above rule, for most of the productions of the Southern and Northern halves differ widely: yet some few living forms, as the opossum, range from the one into the other, as did formerly some of the gigantic Edentata. The Esquimaux, like other Arctic animals, extend round the whole polar regions. It should be observed that the amount of difference between the mammals of the several zoological provinces does not correspond with the degree of separation between the latter; so that it can hardly be considered as an anomaly that the Negro differs more, and the American much less from the other races of man, than do the mammals of the African and American continents from the mammals of the other provinces. Man, it may be added, does not appear to have aboriginally inhabited any oceanic island; and in this respect, he resembles the other members of his class. In determining whether the supposed varieties of the same kind of domestic animal should be ranked as such, or as specifically distinct, that is, whether any of them are descended from distinct wild species, every naturalist would lay much stress on the fact of their external parasites being specifically distinct. All the more stress would be laid on this fact, as it would be an exceptional one; for I am informed by Mr. Denny that the most different kinds of dogs, fowls, and pigeons, in England, are infested by the same species of Pediculi or lice. Now Mr. A. Murray has carefully examined the Pediculi collected in different countries from the different races of man (8. 'Transactions of the Royal Society of Edinburgh,' vol. xxii, 1861, p. 567.); and he finds that they differ, not only in colour, but in the structure of their claws and limbs. In every case in which many specimens were obtained the differences were constant. The surgeon of a whaling ship in the Pacific assured me that when the Pediculi, with which some Sandwich Islanders on board swarmed, strayed on to the bodies of the English sailors, they died in the course of three or four days. These Pediculi were darker coloured, and appeared different from those proper to the natives of Chiloe in South America, of which he gave me specimens. These, again, appeared larger and much softer than European lice. Mr. Murray procured four kinds from Africa, namely, from the Negroes of the Eastern and Western coasts, from the Hottentots and Kaffirs; two kinds from the natives of Australia; two from North and two from South America. In these latter cases it may be presumed that the Pediculi came from natives inhabiting different districts. With insects slight structural differences, if constant, are generally esteemed of specific value: and the fact of the races of man being infested by parasites, which appear to be specifically distinct, might fairly be urged as an argument that the races themselves ought to be classed as distinct species. Our supposed naturalist having proceeded thus far in his investigation, would next enquire whether the races of men, when crossed, were in any degree sterile. He might consult the work (9. 'On the Phenomena of Hybridity in the Genus Homo,' Eng. translat., 1864.) of Professor Broca, a cautious and philosophical observer, and in this he would find good evidence that some races were quite fertile together, but evidence of an opposite nature in regard to other races. Thus it has been asserted that the native women of Australia and Tasmania rarely produce children to European men; the evidence, however, on this head has now been shewn to be almost valueless. The half-castes are killed by the pure blacks: and an account has lately been published of eleven half-caste youths murdered and burnt at the same time, whose remains were found by the police. (10. See the interesting letter by Mr. T.A. Murray, in the 'Anthropological Review,' April 1868, p. liii. In this letter Count Strzelecki's statement that Australian women who have borne children to a white man, are afterwards sterile with their own race, is disproved. M. A. de Quatrefages has also collected (Revue des Cours Scientifiques, March, 1869, p. 239), much evidence that Australians and Europeans are not sterile when crossed.) Again, it has often been said that when mulattoes intermarry, they produce few children; on the other hand, Dr. Bachman, of Charleston (11. 'An Examination of Prof. Agassiz's Sketch of the Nat. Provinces of the Animal World,' Charleston, 1855, p. 44.), positively asserts that he has known mulatto families which have intermarried for several generations, and have continued on an average as fertile as either pure whites or pure blacks. Enquiries formerly made by Sir C. Lyell on this subject led him, as he informs me, to the same conclusion. (12. Dr. Rohlfs writes to me that he found the mixed races in the Great Sahara, derived from Arabs, Berbers, and Negroes of three tribes, extraordinarily fertile. On the other hand, Mr. Winwood Reade informs me that the Negroes on the Gold Coast, though admiring white men and mulattoes, have a maxim that mulattoes should not intermarry, as the children are few and sickly. This belief, as Mr. Reade remarks, deserves attention, as white men have visited and resided on the Gold Coast for four hundred years, so that the natives have had ample time to gain knowledge through experience.) In the United States the census for the year 1854 included, according to Dr. Bachman, 405,751 mulattoes; and this number, considering all the circumstances of the case, seems small; but it may partly be accounted for by the degraded and anomalous position of the class, and by the profligacy of the women. A certain amount of absorption of mulattoes into negroes must always be in progress; and this would lead to an apparent diminution of the former. The inferior vitality of mulattoes is spoken of in a trustworthy work (13. 'Military and Anthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p. 319.) as a well-known phenomenon; and this, although a different consideration from their lessened fertility, may perhaps be advanced as a proof of the specific distinctness of the parent races. No doubt both animal and vegetable hybrids, when produced from extremely distinct species, are liable to premature death; but the parents of mulattoes cannot be put under the category of extremely distinct species. The common Mule, so notorious for long life and vigour, and yet so sterile, shews how little necessary connection there is in hybrids between lessened fertility and vitality; other analogous cases could be cited. Even if it should hereafter be proved that all the races of men were perfectly fertile together, he who was inclined from other reasons to rank them as distinct species, might with justice argue that fertility and sterility are not safe criterions of specific distinctness. We know that these qualities are easily affected by changed conditions of life, or by close inter-breeding, and that they are governed by highly complex laws, for instance, that of the unequal fertility of converse crosses between the same two species. With forms which must be ranked as undoubted species, a perfect series exists from those which are absolutely sterile when crossed, to those which are almost or completely fertile. The degrees of sterility do not coincide strictly with the degrees of difference between the parents in external structure or habits of life. Man in many respects may be compared with those animals which have long been domesticated, and a large body of evidence can be advanced in favour of the Pallasian doctrine (14. The 'Variation of Animals and Plants under Domestication,' vol. ii. p. 109. I may here remind the reader that the sterility of species when crossed is not a specially-acquired quality, but, like the incapacity of certain trees to be grafted together, is incidental on other acquired differences. The nature of these differences is unknown, but they relate more especially to the reproductive system, and much less so to external structure or to ordinary differences in constitution. One important element in the sterility of crossed species apparently lies in one or both having been long habituated to fixed conditions; for we know that changed conditions have a special influence on the reproductive system, and we have good reason to believe (as before remarked) that the fluctuating conditions of domestication tend to eliminate that sterility which is so general with species, in a natural state, when crossed. It has elsewhere been shewn by me (ibid. vol. ii. p. 185, and 'Origin of Species,' 5th edit. p. 317), that the sterility of crossed species has not been acquired through natural selection: we can see that when two forms have already been rendered very sterile, it is scarcely possible that their sterility should be augmented by the preservation or survival of the more and more sterile individuals; for, as the sterility increases, fewer and fewer offspring will be produced from which to breed, and at last only single individuals will be produced at the rarest intervals. But there is even a higher grade of sterility than this. Both Gartner and Kolreuter have proved that in genera of plants, including many species, a series can be formed from species which, when crossed, yield fewer and fewer seeds, to species which never produce a single seed, but yet are affected by the pollen of the other species, as shewn by the swelling of the germen. It is here manifestly impossible to select the more sterile individuals, which have already ceased to yield seeds; so that the acme of sterility, when the germen alone is affected, cannot have been gained through selection. This acme, and no doubt the other grades of sterility, are the incidental results of certain unknown differences in the constitution of the reproductive system of the species which are crossed.), that domestication tends to eliminate the sterility which is so general a result of the crossing of species in a state of nature. From these several considerations, it may be justly urged that the perfect fertility of the intercrossed races of man, if established, would not absolutely preclude us from ranking them as distinct species. Independently of fertility, the characters presented by the offspring from a cross have been thought to indicate whether or not the parent-forms ought to be ranked as species or varieties; but after carefully studying the evidence, I have come to the conclusion that no general rules of this kind can be trusted. The ordinary result of a cross is the production of a blended or intermediate form; but in certain cases some of the offspring take closely after one parent-form, and some after the other. This is especially apt to occur when the parents differ in characters which first appeared as sudden variations or monstrosities. (15. 'The Variation of Animals,' etc., vol. ii. p. 92.) I refer to this point, because Dr. Rohlfs informs me that he has frequently seen in Africa the offspring of negroes crossed with members of other races, either completely black or completely white, or rarely piebald. On the other hand, it is notorious that in America mulattoes commonly present an intermediate appearance. We have now seen that a naturalist might feel himself fully justified in ranking the races of man as distinct species; for he has found that they are distinguished by many differences in structure and constitution, some being of importance. These differences have, also, remained nearly constant for very long periods of time. Our naturalist will have been in some degree influenced by the enormous range of man, which is a great anomaly in the class of mammals, if mankind be viewed as a single species. He will have been struck with the distribution of the several so-called races, which accords with that of other undoubtedly distinct species of mammals. Finally, he might urge that the mutual fertility of all the races has not as yet been fully proved, and even if proved would not be an absolute proof of their specific identity. On the other side of the question, if our supposed naturalist were to enquire whether the forms of man keep distinct like ordinary species, when mingled together in large numbers in the same country, he would immediately discover that this was by no means the case. In Brazil he would behold an immense mongrel population of Negroes and Portuguese; in Chiloe, and other parts of South America, he would behold the whole population consisting of Indians and Spaniards blended in various degrees. (16. M. de Quatrefages has given ('Anthropological Review,' Jan. 1869, p. 22), an interesting account of the success and energy of the Paulistas in Brazil, who are a much crossed race of Portuguese and Indians, with a mixture of the blood of other races.) In many parts of the same continent he would meet with the most complex crosses between Negroes, Indians, and Europeans; and judging from the vegetable kingdom, such triple crosses afford the severest test of the mutual fertility of the parent forms. In one island of the Pacific he would find a small population of mingled Polynesian and English blood; and in the Fiji Archipelago a population of Polynesian and Negritos crossed in all degrees. Many analogous cases could be added; for instance, in Africa. Hence the races of man are not sufficiently distinct to inhabit the same country without fusion; and the absence of fusion affords the usual and best test of specific distinctness. Our naturalist would likewise be much disturbed as soon as he perceived that the distinctive characters of all the races were highly variable. This fact strikes every one on first beholding the negro slaves in Brazil, who have been imported from all parts of Africa. The same remark holds good with the Polynesians, and with many other races. It may be doubted whether any character can be named which is distinctive of a race and is constant. Savages, even within the limits of the same tribe, are not nearly so uniform in character, as has been often asserted. Hottentot women offer certain peculiarities, more strongly marked than those occurring in any other race, but these are known not to be of constant occurrence. In the several American tribes, colour and hairiness differ considerably; as does colour to a certain degree, and the shape of the features greatly, in the Negroes of Africa. The shape of the skull varies much in some races (17. For instance, with the aborigines of America and Australia, Prof. Huxley says ('Transact. Internat. Congress of Prehist. Arch.' 1868, p. 105), that the skulls of many South Germans and Swiss are "as short and as broad as those of the Tartars," etc.); and so it is with every other character. Now all naturalists have learnt by dearly bought experience, how rash it is to attempt to define species by the aid of inconstant characters. But the most weighty of all the arguments against treating the races of man as distinct species, is that they graduate into each other, independently in many cases, as far as we can judge, of their having intercrossed. Man has been studied more carefully than any other animal, and yet there is the greatest possible diversity amongst capable judges whether he should be classed as a single species or race, or as two (Virey), as three (Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent), sixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-three, according to Burke. (18. See a good discussion on this subject in Waitz, 'Introduction to Anthropology,' Eng. translat., 1863, pp. 198-208, 227. I have taken some of the above statements from H. Tuttle's 'Origin and Antiquity of Physical Man,' Boston, 1866, p. 35.) This diversity of judgment does not prove that the races ought not to be ranked as species, but it shews that they graduate into each other, and that it is hardly possible to discover clear distinctive characters between them. Every naturalist who has had the misfortune to undertake the description of a group of highly varying organisms, has encountered cases (I speak after experience) precisely like that of man; and if of a cautious disposition, he will end by uniting all the forms which graduate into each other, under a single species; for he will say to himself that he has no right to give names to objects which he cannot define. Cases of this kind occur in the Order which includes man, namely in certain genera of monkeys; whilst in other genera, as in Cercopithecus, most of the species can be determined with certainty. In the American genus Cebus, the various forms are ranked by some naturalists as species, by others as mere geographical races. Now if numerous specimens of Cebus were collected from all parts of South America, and those forms which at present appear to be specifically distinct, were found to graduate into each other by close steps, they would usually be ranked as mere varieties or races; and this course has been followed by most naturalists with respect to the races of man. Nevertheless, it must be confessed that there are forms, at least in the vegetable kingdom (19. Prof. Nageli has carefully described several striking cases in his 'Botanische Mittheilungen,' B. ii. 1866, ss. 294-369. Prof. Asa Gray has made analogous remarks on some intermediate forms in the Compositae of N. America.), which we cannot avoid naming as species, but which are connected together by numberless gradations, independently of intercrossing. Some naturalists have lately employed the term "sub-species" to designate forms which possess many of the characteristics of true species, but which hardly deserve so high a rank. Now if we reflect on the weighty arguments above given, for raising the races of man to the dignity of species, and the insuperable difficulties on the other side in defining them, it seems that the term "sub-species" might here be used with propriety. But from long habit the term "race" will perhaps always be employed. The choice of terms is only so far important in that it is desirable to use, as far as possible, the same terms for the same degrees of difference. Unfortunately this can rarely be done: for the larger genera generally include closely-allied forms, which can be distinguished only with much difficulty, whilst the smaller genera within the same family include forms that are perfectly distinct; yet all must be ranked equally as species. So again, species within the same large genus by no means resemble each other to the same degree: on the contrary, some of them can generally be arranged in little groups round other species, like satellites round planets. (20. 'Origin of Species,' 5th edit. p. 68.) The question whether mankind consists of one or several species has of late years been much discussed by anthropologists, who are divided into the two schools of monogenists and polygenists. Those who do not admit the principle of evolution, must look at species as separate creations, or in some manner as distinct entities; and they must decide what forms of man they will consider as species by the analogy of the method commonly pursued in ranking other organic beings as species. But it is a hopeless endeavour to decide this point, until some definition of the term "species" is generally accepted; and the definition must not include an indeterminate element such as an act of creation. We might as well attempt without any definition to decide whether a certain number of houses should be called a village, town, or city. We have a practical illustration of the difficulty in the never-ending doubts whether many closely-allied mammals, birds, insects, and plants, which represent each other respectively in North America and Europe, should be ranked as species or geographical races; and the like holds true of the productions of many islands situated at some little distance from the nearest continent. Those naturalists, on the other hand, who admit the principle of evolution, and this is now admitted by the majority of rising men, will feel no doubt that all the races of man are descended from a single primitive stock; whether or not they may think fit to designate the races as distinct species, for the sake of expressing their amount of difference. (21. See Prof. Huxley to this effect in the 'Fortnightly Review,' 1865, p. 275.) With our domestic animals the question whether the various races have arisen from one or more species is somewhat different. Although it may be admitted that all the races, as well as all the natural species within the same genus, have sprung from the same primitive stock, yet it is a fit subject for discussion, whether all the domestic races of the dog, for instance, have acquired their present amount of difference since some one species was first domesticated by man; or whether they owe some of their characters to inheritance from distinct species, which had already been differentiated in a state of nature. With man no such question can arise, for he cannot be said to have been domesticated at any particular period. During an early stage in the divergence of the races of man from a common stock, the differences between the races and their number must have been small; consequently as far as their distinguishing characters are concerned, they then had less claim to rank as distinct species than the existing so-called races. Nevertheless, so arbitrary is the term of species, that such early races would perhaps have been ranked by some naturalists as distinct species, if their differences, although extremely slight, had been more constant than they are at present, and had not graduated into each other. It is however possible, though far from probable, that the early progenitors of man might formerly have diverged much in character, until they became more unlike each other than any now existing races; but that subsequently, as suggested by Vogt (22. 'Lectures on Man,' Eng. translat., 1864, p. 468.), they converged in character. When man selects the offspring of two distinct species for the same object, he sometimes induces a considerable amount of convergence, as far as general appearance is concerned. This is the case, as shewn by von Nathusius (23. 'Die Rassen des Schweines,' 1860, s. 46. 'Vorstudien für Geschichte,' etc., Schweinesschädel, 1864, s. 104. With respect to cattle, see M. de Quatrefages, 'Unité de l'Espèce Humaine,' 1861, p. 119.), with the improved breeds of the pig, which are descended from two distinct species; and in a less marked manner with the improved breeds of cattle. A great anatomist, Gratiolet, maintains that the anthropomorphous apes do not form a natural sub-group; but that the orang is a highly developed gibbon or semnopithecus, the chimpanzee a highly developed macacus, and the gorilla a highly developed mandrill. If this conclusion, which rests almost exclusively on brain-characters, be admitted, we should have a case of convergence at least in external characters, for the anthropomorphous apes are certainly more like each other in many points, than they are to other apes. All analogical resemblances, as of a whale to a fish, may indeed be said to be cases of convergence; but this term has never been applied to superficial and adaptive resemblances. It would, however, be extremely rash to attribute to convergence close similarity of character in many points of structure amongst the modified descendants of widely distinct beings. The form of a crystal is determined solely by the molecular forces, and it is not surprising that dissimilar substances should sometimes assume the same form; but with organic beings we should bear in mind that the form of each depends on an infinity of complex relations, namely on variations, due to causes far too intricate to be followed,--on the nature of the variations preserved, these depending on the physical conditions, and still more on the surrounding organisms which compete with each,--and lastly, on inheritance (in itself a fluctuating element) from innumerable progenitors, all of which have had their forms determined through equally complex relations. It appears incredible that the modified descendants of two organisms, if these differed from each other in a marked manner, should ever afterwards converge so closely as to lead to a near approach to identity throughout their whole organisation. In the case of the convergent races of pigs above referred to, evidence of their descent from two primitive stocks is, according to von Nathusius, still plainly retained, in certain bones of their skulls. If the races of man had descended, as is supposed by some naturalists, from two or more species, which differed from each other as much, or nearly as much, as does the orang from the gorilla, it can hardly be doubted that marked differences in the structure of certain bones would still be discoverable in man as he now exists. Although the existing races of man differ in many respects, as in colour, hair, shape of skull, proportions of the body, etc., yet if their whole structure be taken into consideration they are found to resemble each other closely in a multitude of points. Many of these are of so unimportant or of so singular a nature, that it is extremely improbable that they should have been independently acquired by aboriginally distinct species or races. The same remark holds good with equal or greater force with respect to the numerous points of mental similarity between the most distinct races of man. The American aborigines, Negroes and Europeans are as different from each other in mind as any three races that can be named; yet I was incessantly struck, whilst living with the Fuegians on board the "Beagle," with the many little traits of character, shewing how similar their minds were to ours; and so it was with a full-blooded negro with whom I happened once to be intimate. He who will read Mr. Tylor's and Sir J. Lubbock's interesting works (24. Tylor's 'Early History of Mankind,' 1865: with respect to gesture-language, see p. 54. Lubbock's 'Prehistoric Times,' 2nd edit. 1869.) can hardly fail to be deeply impressed with the close similarity between the men of all races in tastes, dispositions and habits. This is shewn by the pleasure which they all take in dancing, rude music, acting, painting, tattooing, and otherwise decorating themselves; in their mutual comprehension of gesture-language, by the same expression in their features, and by the same inarticulate cries, when excited by the same emotions. This similarity, or rather identity, is striking, when contrasted with the different expressions and cries made by distinct species of monkeys. There is good evidence that the art of shooting with bows and arrows has not been handed down from any common progenitor of mankind, yet as Westropp and Nilsson have remarked (25. 'On Analogous Forms of Implements,' in 'Memoirs of Anthropological Society' by H.M. Westropp. 'The Primitive Inhabitants of Scandinavia,' Eng. translat., edited by Sir J. Lubbock, 1868, p. 104.), the stone arrow-heads, brought from the most distant parts of the world, and manufactured at the most remote periods, are almost identical; and this fact can only be accounted for by the various races having similar inventive or mental powers. The same observation has been made by archaeologists (26. Westropp 'On Cromlechs,' etc., 'Journal of Ethnological Soc.' as given in 'Scientific Opinion,' June 2nd, 1869, p. 3.) with respect to certain widely-prevalent ornaments, such as zig-zags, etc.; and with respect to various simple beliefs and customs, such as the burying of the dead under megalithic structures. I remember observing in South America (27. 'Journal of Researches: Voyage of the "Beagle,"' p. 46.), that there, as in so many other parts of the world, men have generally chosen the summits of lofty hills, to throw up piles of stones, either as a record of some remarkable event, or for burying their dead. Now when naturalists observe a close agreement in numerous small details of habits, tastes, and dispositions between two or more domestic races, or between nearly-allied natural forms, they use this fact as an argument that they are descended from a common progenitor who was thus endowed; and consequently that all should be classed under the same species. The same argument may be applied with much force to the races of man. As it is improbable that the numerous and unimportant points of resemblance between the several races of man in bodily structure and mental faculties (I do not here refer to similar customs) should all have been independently acquired, they must have been inherited from progenitors who had these same characters. We thus gain some insight into the early state of man, before he had spread step by step over the face of the earth. The spreading of man to regions widely separated by the sea, no doubt, preceded any great amount of divergence of character in the several races; for otherwise we should sometimes meet with the same race in distinct continents; and this is never the case. Sir J. Lubbock, after comparing the arts now practised by savages in all parts of the world, specifies those which man could not have known, when he first wandered from his original birthplace; for if once learnt they would never have been forgotten. (28. 'Prehistoric Times,' 1869, p. 574.) He thus shews that "the spear, which is but a development of the knife-point, and the club, which is but a long hammer, are the only things left." He admits, however, that the art of making fire probably had been already discovered, for it is common to all the races now existing, and was known to the ancient cave-inhabitants of Europe. Perhaps the art of making rude canoes or rafts was likewise known; but as man existed at a remote epoch, when the land in many places stood at a very different level to what it does now, he would have been able, without the aid of canoes, to have spread widely. Sir J. Lubbock further remarks how improbable it is that our earliest ancestors could have "counted as high as ten, considering that so many races now in existence cannot get beyond four." Nevertheless, at this early period, the intellectual and social faculties of man could hardly have been inferior in any extreme degree to those possessed at present by the lowest savages; otherwise primeval man could not have been so eminently successful in the struggle for life, as proved by his early and wide diffusion. From the fundamental differences between certain languages, some philologists have inferred that when man first became widely diffused, he was not a speaking animal; but it may be suspected that languages, far less perfect than any now spoken, aided by gestures, might have been used, and yet have left no traces on subsequent and more highly-developed tongues. Without the use of some language, however imperfect, it appears doubtful whether man's intellect could have risen to the standard implied by his dominant position at an early period. Whether primeval man, when he possessed but few arts, and those of the rudest kind, and when his power of language was extremely imperfect, would have deserved to be called man, must depend on the definition which we employ. In a series of forms graduating insensibly from some ape-like creature to man as he now exists, it would be impossible to fix on any definite point where the term "man" ought to be used. But this is a matter of very little importance. So again, it is almost a matter of indifference whether the so-called races of man are thus designated, or are ranked as species or sub-species; but the latter term appears the more appropriate. Finally, we may conclude that when the principle of evolution is generally accepted, as it surely will be before long, the dispute between the monogenists and the polygenists will die a silent and unobserved death. One other question ought not to be passed over without notice, namely, whether, as is sometimes assumed, each sub-species or race of man has sprung from a single pair of progenitors. With our domestic animals a new race can readily be formed by carefully matching the varying offspring from a single pair, or even from a single individual possessing some new character; but most of our races have been formed, not intentionally from a selected pair, but unconsciously by the preservation of many individuals which have varied, however slightly, in some useful or desired manner. If in one country stronger and heavier horses, and in another country lighter and fleeter ones, were habitually preferred, we may feel sure that two distinct sub-breeds would be produced in the course of time, without any one pair having been separated and bred from, in either country. Many races have been thus formed, and their manner of formation is closely analogous to that of natural species. We know, also, that the horses taken to the Falkland Islands have, during successive generations, become smaller and weaker, whilst those which have run wild on the Pampas have acquired larger and coarser heads; and such changes are manifestly due, not to any one pair, but to all the individuals having been subjected to the same conditions, aided, perhaps, by the principle of reversion. The new sub-breeds in such cases are not descended from any single pair, but from many individuals which have varied in different degrees, but in the same general manner; and we may conclude that the races of man have been similarly produced, the modifications being either the direct result of exposure to different conditions, or the indirect result of some form of selection. But to this latter subject we shall presently return. ON THE EXTINCTION OF THE RACES OF MAN. The partial or complete extinction of many races and sub-races of man is historically known. Humboldt saw in South America a parrot which was the sole living creature that could speak a word of the language of a lost tribe. Ancient monuments and stone implements found in all parts of the world, about which no tradition has been preserved by the present inhabitants, indicate much extinction. Some small and broken tribes, remnants of former races, still survive in isolated and generally mountainous districts. In Europe the ancient races were all, according to Shaaffhausen (29. Translation in 'Anthropological Review,' Oct. 1868, p. 431.), "lower in the scale than the rudest living savages"; they must therefore have differed, to a certain extent, from any existing race. The remains described by Professor Broca from Les Eyzies, though they unfortunately appear to have belonged to a single family, indicate a race with a most singular combination of low or simious, and of high characteristics. This race is "entirely different from any other, ancient or modern, that we have heard of." (30. 'Transactions, International Congress of Prehistoric Archaeology' 1868, pp. 172-175. See also Broca (tr.) in 'Anthropological Review,' Oct. 1868, p. 410.) It differed, therefore, from the quaternary race of the caverns of Belgium. Man can long resist conditions which appear extremely unfavourable for his existence. (31. Dr. Gerland, 'Ueber das Aussterben der Naturvölker,' 1868, s. 82.) He has long lived in the extreme regions of the North, with no wood for his canoes or implements, and with only blubber as fuel, and melted snow as drink. In the southern extremity of America the Fuegians survive without the protection of clothes, or of any building worthy to be called a hovel. In South Africa the aborigines wander over arid plains, where dangerous beasts abound. Man can withstand the deadly influence of the Terai at the foot of the Himalaya, and the pestilential shores of tropical Africa. Extinction follows chiefly from the competition of tribe with tribe, and race with race. Various checks are always in action, serving to keep down the numbers of each savage tribe,--such as periodical famines, nomadic habits and the consequent deaths of infants, prolonged suckling, wars, accidents, sickness, licentiousness, the stealing of women, infanticide, and especially lessened fertility. If any one of these checks increases in power, even slightly, the tribe thus affected tends to decrease; and when of two adjoining tribes one becomes less numerous and less powerful than the other, the contest is soon settled by war, slaughter, cannibalism, slavery, and absorption. Even when a weaker tribe is not thus abruptly swept away, if it once begins to decrease, it generally goes on decreasing until it becomes extinct. (32. Gerland (ibid. s. 12) gives facts in support of this statement.) When civilised nations come into contact with barbarians the struggle is short, except where a deadly climate gives its aid to the native race. Of the causes which lead to the victory of civilised nations, some are plain and simple, others complex and obscure. We can see that the cultivation of the land will be fatal in many ways to savages, for they cannot, or will not, change their habits. New diseases and vices have in some cases proved highly destructive; and it appears that a new disease often causes much death, until those who are most susceptible to its destructive influence are gradually weeded out (33. See remarks to this effect in Sir H. Holland's 'Medical Notes and Reflections,' 1839, p. 390.); and so it may be with the evil effects from spirituous liquors, as well as with the unconquerably strong taste for them shewn by so many savages. It further appears, mysterious as is the fact, that the first meeting of distinct and separated people generates disease. (34. I have collected ('Journal of Researches: Voyage of the "Beagle,"' p. 435) a good many cases bearing on this subject; see also Gerland, ibid. s. 8. Poeppig speaks of the "breath of civilisation as poisonous to savages.") Mr. Sproat, who in Vancouver Island closely attended to the subject of extinction, believed that changed habits of life, consequent on the advent of Europeans, induces much ill health. He lays, also, great stress on the apparently trifling cause that the natives become "bewildered and dull by the new life around them; they lose the motives for exertion, and get no new ones in their place." (35. Sproat, 'Scenes and Studies of Savage Life,' 1868, p. 284.) The grade of their civilisation seems to be a most important element in the success of competing nations. A few centuries ago Europe feared the inroads of Eastern barbarians; now any such fear would be ridiculous. It is a more curious fact, as Mr. Bagehot has remarked, that savages did not formerly waste away before the classical nations, as they now do before modern civilised nations; had they done so, the old moralists would have mused over the event; but there is no lament in any writer of that period over the perishing barbarians. (36. Bagehot, 'Physics and Politics,' 'Fortnightly Review,' April 1, 1868, p. 455.) The most potent of all the causes of extinction, appears in many cases to be lessened fertility and ill-health, especially amongst the children, arising from changed conditions of life, notwithstanding that the new conditions may not be injurious in themselves. I am much indebted to Mr. H.H. Howorth for having called my attention to this subject, and for having given me information respecting it. I have collected the following cases. When Tasmania was first colonised the natives were roughly estimated by some at 7000 and by others at 20,000. Their number was soon greatly reduced, chiefly by fighting with the English and with each other. After the famous hunt by all the colonists, when the remaining natives delivered themselves up to the government, they consisted only of 120 individuals (37. All the statements here given are taken from 'The Last of the Tasmanians,' by J. Bonwick, 1870.), who were in 1832 transported to Flinders Island. This island, situated between Tasmania and Australia, is forty miles long, and from twelve to eighteen miles broad: it seems healthy, and the natives were well treated. Nevertheless, they suffered greatly in health. In 1834 they consisted (Bonwick, p. 250) of forty-seven adult males, forty-eight adult females, and sixteen children, or in all of 111 souls. In 1835 only one hundred were left. As they continued rapidly to decrease, and as they themselves thought that they should not perish so quickly elsewhere, they were removed in 1847 to Oyster Cove in the southern part of Tasmania. They then consisted (Dec. 20th, 1847) of fourteen men, twenty-two women and ten children. (38. This is the statement of the Governor of Tasmania, Sir W. Denison, 'Varieties of Vice-Regal Life,' 1870, vol. i. p. 67.) But the change of site did no good. Disease and death still pursued them, and in 1864 one man (who died in 1869), and three elderly women alone survived. The infertility of the women is even a more remarkable fact than the liability of all to ill-health and death. At the time when only nine women were left at Oyster Cove, they told Mr. Bonwick (p. 386), that only two had ever borne children: and these two had together produced only three children! With respect to the cause of this extraordinary state of things, Dr. Story remarks that death followed the attempts to civilise the natives. "If left to themselves to roam as they were wont and undisturbed, they would have reared more children, and there would have been less mortality." Another careful observer of the natives, Mr. Davis, remarks, "The births have been few and the deaths numerous. This may have been in a great measure owing to their change of living and food; but more so to their banishment from the mainland of Van Diemen's Land, and consequent depression of spirits" (Bonwick, pp. 388, 390). Similar facts have been observed in two widely different parts of Australia. The celebrated explorer, Mr. Gregory, told Mr. Bonwick, that in Queensland "the want of reproduction was being already felt with the blacks, even in the most recently settled parts, and that decay would set in." Of thirteen aborigines from Shark's Bay who visited Murchison River, twelve died of consumption within three months. (39. For these cases, see Bonwick's 'Daily Life of the Tasmanians,' 1870, p. 90: and the 'Last of the Tasmanians,' 1870, p. 386.) The decrease of the Maories of New Zealand has been carefully investigated by Mr. Fenton, in an admirable Report, from which all the following statements, with one exception, are taken. (40. 'Observations on the Aboriginal Inhabitants of New Zealand,' published by the Government, 1859.) The decrease in number since 1830 is admitted by every one, including the natives themselves, and is still steadily progressing. Although it has hitherto been found impossible to take an actual census of the natives, their numbers were carefully estimated by residents in many districts. The result seems trustworthy, and shows that during the fourteen years, previous to 1858, the decrease was 19.42 per cent. Some of the tribes, thus carefully examined, lived above a hundred miles apart, some on the coast, some inland; and their means of subsistence and habits differed to a certain extent (p. 28). The total number in 1858 was believed to be 53,700, and in 1872, after a second interval of fourteen years, another census was taken, and the number is given as only 36,359, shewing a decrease of 32.29 per cent! (41. 'New Zealand,' by Alex. Kennedy, 1873, p. 47.) Mr. Fenton, after shewing in detail the insufficiency of the various causes, usually assigned in explanation of this extraordinary decrease, such as new diseases, the profligacy of the women, drunkenness, wars, etc., concludes on weighty grounds that it depends chiefly on the unproductiveness of the women, and on the extraordinary mortality of the young children (pp. 31, 34). In proof of this he shews (p. 33) that in 1844 there was one non-adult for every 2.57 adults; whereas in 1858 there was only one non-adult for every 3.27 adults. The mortality of the adults is also great. He adduces as a further cause of the decrease the inequality of the sexes; for fewer females are born than males. To this latter point, depending perhaps on a widely distinct cause, I shall return in a future chapter. Mr. Fenton contrasts with astonishment the decrease in New Zealand with the increase in Ireland; countries not very dissimilar in climate, and where the inhabitants now follow nearly similar habits. The Maories themselves (p. 35) "attribute their decadence, in some measure, to the introduction of new food and clothing, and the attendant change of habits"; and it will be seen, when we consider the influence of changed conditions on fertility, that they are probably right. The diminution began between the years 1830 and 1840; and Mr. Fenton shews (p. 40) that about 1830, the art of manufacturing putrid corn (maize), by long steeping in water, was discovered and largely practised; and this proves that a change of habits was beginning amongst the natives, even when New Zealand was only thinly inhabited by Europeans. When I visited the Bay of Islands in 1835, the dress and food of the inhabitants had already been much modified: they raised potatoes, maize, and other agricultural produce, and exchanged them for English manufactured goods and tobacco. It is evident from many statements in the life of Bishop Patteson (42. 'Life of J.C. Patteson,' by C.M. Younge, 1874; see more especially vol. i. p. 530.), that the Melanesians of the New Hebrides and neighbouring archipelagoes, suffered to an extraordinary degree in health, and perished in large numbers, when they were removed to New Zealand, Norfolk Island, and other salubrious places, in order to be educated as missionaries. The decrease of the native population of the Sandwich Islands is as notorious as that of New Zealand. It has been roughly estimated by those best capable of judging, that when Cook discovered the Islands in 1779, the population amounted to about 300,000. According to a loose census in 1823, the numbers then were 142,050. In 1832, and at several subsequent periods, an accurate census was officially taken, but I have been able to obtain only the following returns: Native Population Annual rate of decrease per cent., assuming it to (Except during 1832 and have been uniform between 1836, when the few the successive censuses; foreigners in the islands these censuses being taken Year were included.) at irregular intervals. 1832 130,313 4.46 1836 108,579 2.47 1853 71,019 0.81 1860 67,084 2.18 1866 58,765 2.17 1872 51,531 We here see that in the interval of forty years, between 1832 and 1872, the population has decreased no less than sixty-eight per cent.! This has been attributed by most writers to the profligacy of the women, to former bloody wars, and to the severe labour imposed on conquered tribes and to newly introduced diseases, which have been on several occasions extremely destructive. No doubt these and other such causes have been highly efficient, and may account for the extraordinary rate of decrease between the years 1832 and 1836; but the most potent of all the causes seems to be lessened fertility. According to Dr. Ruschenberger of the U.S. Navy, who visited these islands between 1835 and 1837, in one district of Hawaii, only twenty-five men out of 1134, and in another district only ten out of 637, had a family with as many as three children. Of eighty married women, only thirty-nine had ever borne children; and "the official report gives an average of half a child to each married couple in the whole island." This is almost exactly the same average as with the Tasmanians at Oyster Cove. Jarves, who published his History in 1843, says that "families who have three children are freed from all taxes; those having more, are rewarded by gifts of land and other encouragements." This unparalleled enactment by the government well shews how infertile the race had become. The Rev. A. Bishop stated in the Hawaiian 'Spectator' in 1839, that a large proportion of the children die at early ages, and Bishop Staley informs me that this is still the case, just as in New Zealand. This has been attributed to the neglect of the children by the women, but it is probably in large part due to innate weakness of constitution in the children, in relation to the lessened fertility of their parents. There is, moreover, a further resemblance to the case of New Zealand, in the fact that there is a large excess of male over female births: the census of 1872 gives 31,650 males to 25,247 females of all ages, that is 125.36 males for every 100 females; whereas in all civilised countries the females exceed the males. No doubt the profligacy of the women may in part account for their small fertility; but their changed habits of life is a much more probable cause, and which will at the same time account for the increased mortality, especially of the children. The islands were visited by Cook in 1779, Vancouver in 1794, and often subsequently by whalers. In 1819 missionaries arrived, and found that idolatry had been already abolished, and other changes effected by the king. After this period there was a rapid change in almost all the habits of life of the natives, and they soon became "the most civilised of the Pacific Islanders." One of my informants, Mr. Coan, who was born on the islands, remarks that the natives have undergone a greater change in their habits of life in the course of fifty years than Englishmen during a thousand years. From information received from Bishop Staley, it does not appear that the poorer classes have ever much changed their diet, although many new kinds of fruit have been introduced, and the sugar-cane is in universal use. Owing, however, to their passion for imitating Europeans, they altered their manner of dressing at an early period, and the use of alcoholic drinks became very general. Although these changes appear inconsiderable, I can well believe, from what is known with respect to animals, that they might suffice to lessen the fertility of the natives. (43. The foregoing statements are taken chiefly from the following works: Jarves' 'History of the Hawaiian Islands,' 1843, pp. 400-407. Cheever, 'Life in the Sandwich Islands,' 1851, p. 277. Ruschenberger is quoted by Bonwick, 'Last of the Tasmanians,' 1870, p. 378. Bishop is quoted by Sir E. Belcher, 'Voyage Round the World,' 1843, vol. i. p. 272. I owe the census of the several years to the kindness of Mr. Coan, at the request of Dr. Youmans of New York; and in most cases I have compared the Youmans figures with those given in several of the above-named works. I have omitted the census for 1850, as I have seen two widely different numbers given.) Lastly, Mr. Macnamara states (44. 'The Indian Medical Gazette,' Nov. 1, 1871, p. 240.) that the low and degraded inhabitants of the Andaman Islands, on the eastern side of the Gulf of Bengal, are "eminently susceptible to any change of climate: in fact, take them away from their island homes, and they are almost certain to die, and that independently of diet or extraneous influences." He further states that the inhabitants of the Valley of Nepal, which is extremely hot in summer, and also the various hill-tribes of India, suffer from dysentery and fever when on the plains; and they die if they attempt to pass the whole year there. We thus see that many of the wilder races of man are apt to suffer much in health when subjected to changed conditions or habits of life, and not exclusively from being transported to a new climate. Mere alterations in habits, which do not appear injurious in themselves, seem to have this same effect; and in several cases the children are particularly liable to suffer. It has often been said, as Mr. Macnamara remarks, that man can resist with impunity the greatest diversities of climate and other changes; but this is true only of the civilised races. Man in his wild condition seems to be in this respect almost as susceptible as his nearest allies, the anthropoid apes, which have never yet survived long, when removed from their native country. Lessened fertility from changed conditions, as in the case of the Tasmanians, Maories, Sandwich Islanders, and apparently the Australians, is still more interesting than their liability to ill-health and death; for even a slight degree of infertility, combined with those other causes which tend to check the increase of every population, would sooner or later lead to extinction. The diminution of fertility may be explained in some cases by the profligacy of the women (as until lately with the Tahitians), but Mr. Fenton has shewn that this explanation by no means suffices with the New Zealanders, nor does it with the Tasmanians. In the paper above quoted, Mr. Macnamara gives reasons for believing that the inhabitants of districts subject to malaria are apt to be sterile; but this cannot apply in several of the above cases. Some writers have suggested that the aborigines of islands have suffered in fertility and health from long continued inter-breeding; but in the above cases infertility has coincided too closely with the arrival of Europeans for us to admit this explanation. Nor have we at present any reason to believe that man is highly sensitive to the evil effects of inter-breeding, especially in areas so large as New Zealand, and the Sandwich archipelago with its diversified stations. On the contrary, it is known that the present inhabitants of Norfolk Island are nearly all cousins or near relations, as are the Todas in India, and the inhabitants of some of the Western Islands of Scotland; and yet they seem not to have suffered in fertility. (45. On the close relationship of the Norfolk Islanders, Sir W. Denison, 'Varieties of Vice-Regal Life,' vol. i. 1870, p. 410. For the Todas, see Col. Marshall's work 1873, p. 110. For the Western Islands of Scotland, Dr. Mitchell, 'Edinburgh Medical Journal,' March to June, 1865.) A much more probable view is suggested by the analogy of the lower animals. The reproductive system can be shewn to be susceptible to an extraordinary degree (though why we know not) to changed conditions of life; and this susceptibility leads both to beneficial and to evil results. A large collection of facts on this subject is given in chap. xviii. of vol. ii. of my 'Variation of Animals and Plants under Domestication.' I can here give only the briefest abstract; and every one interested in the subject may consult the above work. Very slight changes increase the health, vigour, and fertility of most or all organic beings, whilst other changes are known to render a large number of animals sterile. One of the most familiar cases, is that of tamed elephants not breeding in India; though they often breed in Ava, where the females are allowed to roam about the forests to some extent, and are thus placed under more natural conditions. The case of various American monkeys, both sexes of which have been kept for many years together in their own countries, and yet have very rarely or never bred, is a more apposite instance, because of their relationship to man. It is remarkable how slight a change in the conditions often induces sterility in a wild animal when captured; and this is the more strange as all our domesticated animals have become more fertile than they were in a state of nature; and some of them can resist the most unnatural conditions with undiminished fertility. (46. For the evidence on this head, see 'Variation of Animals,' etc., vol. ii. p. 111.) Certain groups of animals are much more liable than others to be affected by captivity; and generally all the species of the same group are affected in the same manner. But sometimes a single species in a group is rendered sterile, whilst the others are not so; on the other hand, a single species may retain its fertility whilst most of the others fail to breed. The males and females of some species when confined, or when allowed to live almost, but not quite free, in their native country, never unite; others thus circumstanced frequently unite but never produce offspring; others again produce some offspring, but fewer than in a state of nature; and as bearing on the above cases of man, it is important to remark that the young are apt to be weak and sickly, or malformed, and to perish at an early age. Seeing how general is this law of the susceptibility of the reproductive system to changed conditions of life, and that it holds good with our nearest allies, the Quadrumana, I can hardly doubt that it applies to man in his primeval state. Hence if savages of any race are induced suddenly to change their habits of life, they become more or less sterile, and their young offspring suffer in health, in the same manner and from the same cause, as do the elephant and hunting-leopard in India, many monkeys in America, and a host of animals of all kinds, on removal from their natural conditions. We can see why it is that aborigines, who have long inhabited islands, and who must have been long exposed to nearly uniform conditions, should be specially affected by any change in their habits, as seems to be the case. Civilised races can certainly resist changes of all kinds far better than savages; and in this respect they resemble domesticated animals, for though the latter sometimes suffer in health (for instance European dogs in India), yet they are rarely rendered sterile, though a few such instances have been recorded. (47. 'Variation of Animals,' etc., vol. ii. p. 16.) The immunity of civilised races and domesticated animals is probably due to their having been subjected to a greater extent, and therefore having grown somewhat more accustomed, to diversified or varying conditions, than the majority of wild animals; and to their having formerly immigrated or been carried from country to country, and to different families or sub-races having inter-crossed. It appears that a cross with civilised races at once gives to an aboriginal race an immunity from the evil consequences of changed conditions. Thus the crossed offspring from the Tahitians and English, when settled in Pitcairn Island, increased so rapidly that the island was soon overstocked; and in June 1856 they were removed to Norfolk Island. They then consisted of 60 married persons and 134 children, making a total of 194. Here they likewise increased so rapidly, that although sixteen of them returned to Pitcairn Island in 1859, they numbered in January 1868, 300 souls; the males and females being in exactly equal numbers. What a contrast does this case present with that of the Tasmanians; the Norfolk Islanders INCREASED in only twelve and a half years from 194 to 300; whereas the Tasmanians DECREASED during fifteen years from 120 to 46, of which latter number only ten were children. (48. These details are taken from 'The Mutineers of the "Bounty,"' by Lady Belcher, 1870; and from 'Pitcairn Island,' ordered to be printed by the House of Commons, May 29, 1863. The following statements about the Sandwich Islanders are from the 'Honolulu Gazette,' and from Mr. Coan.) So again in the interval between the census of 1866 and 1872 the natives of full blood in the Sandwich Islands decreased by 8081, whilst the half-castes, who are believed to be healthier, increased by 847; but I do not know whether the latter number includes the offspring from the half-castes, or only the half-castes of the first generation. The cases which I have here given all relate to aborigines, who have been subjected to new conditions as the result of the immigration of civilised men. But sterility and ill-health would probably follow, if savages were compelled by any cause, such as the inroad of a conquering tribe, to desert their homes and to change their habits. It is an interesting circumstance that the chief check to wild animals becoming domesticated, which implies the power of their breeding freely when first captured, and one chief check to wild men, when brought into contact with civilisation, surviving to form a civilised race, is the same, namely, sterility from changed conditions of life. Finally, although the gradual decrease and ultimate extinction of the races of man is a highly complex problem, depending on many causes which differ in different places and at different times; it is the same problem as that presented by the extinction of one of the higher animals--of the fossil horse, for instance, which disappeared from South America, soon afterwards to be replaced, within the same districts, by countless troups of the Spanish horse. The New Zealander seems conscious of this parallelism, for he compares his future fate with that of the native rat now almost exterminated by the European rat. Though the difficulty is great to our imagination, and really great, if we wish to ascertain the precise causes and their manner of action, it ought not to be so to our reason, as long as we keep steadily in mind that the increase of each species and each race is constantly checked in various ways; so that if any new check, even a slight one, be superadded, the race will surely decrease in number; and decreasing numbers will sooner or later lead to extinction; the end, in most cases, being promptly determined by the inroads of conquering tribes. ON THE FORMATION OF THE RACES OF MAN. In some cases the crossing of distinct races has led to the formation of a new race. The singular fact that the Europeans and Hindoos, who belong to the same Aryan stock, and speak a language fundamentally the same, differ widely in appearance, whilst Europeans differ but little from Jews, who belong to the Semitic stock, and speak quite another language, has been accounted for by Broca (49. 'On Anthropology,' translation, 'Anthropological Review,' Jan. 1868, p. 38.), through certain Aryan branches having been largely crossed by indigenous tribes during their wide diffusion. When two races in close contact cross, the first result is a heterogeneous mixture: thus Mr. Hunter, in describing the Santali or hill-tribes of India, says that hundreds of imperceptible gradations may be traced "from the black, squat tribes of the mountains to the tall olive-coloured Brahman, with his intellectual brow, calm eyes, and high but narrow head"; so that it is necessary in courts of justice to ask the witnesses whether they are Santalis or Hindoos. (50. 'The Annals of Rural Bengal,' 1868, p. 134.) Whether a heterogeneous people, such as the inhabitants of some of the Polynesian islands, formed by the crossing of two distinct races, with few or no pure members left, would ever become homogeneous, is not known from direct evidence. But as with our domesticated animals, a cross-breed can certainly be fixed and made uniform by careful selection (51. 'The Variation of Animals and Plants under Domestication,' vol. ii. p. 95.) in the course of a few generations, we may infer that the free intercrossing of a heterogeneous mixture during a long descent would supply the place of selection, and overcome any tendency to reversion; so that the crossed race would ultimately become homogeneous, though it might not partake in an equal degree of the characters of the two parent-races. Of all the differences between the races of man, the colour of the skin is the most conspicuous and one of the best marked. It was formerly thought that differences of this kind could be accounted for by long exposure to different climates; but Pallas first shewed that this is not tenable, and he has since been followed by almost all anthropologists. (52. Pallas, 'Act. Acad. St. Petersburg,' 1780, part ii. p. 69. He was followed by Rudolphi, in his 'Beytrage zur Anthropologie,' 1812. An excellent summary of the evidence is given by Godron, 'De l'Espèce,' 1859, vol. ii. p. 246, etc.) This view has been rejected chiefly because the distribution of the variously coloured races, most of whom must have long inhabited their present homes, does not coincide with corresponding differences of climate. Some little weight may be given to such cases as that of the Dutch families, who, as we hear on excellent authority (53. Sir Andrew Smith, as quoted by Knox, 'Races of Man,' 1850, p. 473.), have not undergone the least change of colour after residing for three centuries in South Africa. An argument on the same side may likewise be drawn from the uniform appearance in various parts of the world of gipsies and Jews, though the uniformity of the latter has been somewhat exaggerated. (54. See De Quatrefages on this head, 'Revue des Cours Scientifiques,' Oct. 17, 1868, p. 731.) A very damp or a very dry atmosphere has been supposed to be more influential in modifying the colour of the skin than mere heat; but as D'Orbigny in South America, and Livingstone in Africa, arrived at diametrically opposite conclusions with respect to dampness and dryness, any conclusion on this head must be considered as very doubtful. (55. Livingstone's 'Travels and Researches in S. Africa,' 1857, pp. 338, 339. D'Orbigny, as quoted by Godron, 'De l'Espece,' vol. ii. p. 266.) Various facts, which I have given elsewhere, prove that the colour of the skin and hair is sometimes correlated in a surprising manner with a complete immunity from the action of certain vegetable poisons, and from the attacks of certain parasites. Hence it occurred to me, that negroes and other dark races might have acquired their dark tints by the darker individuals escaping from the deadly influence of the miasma of their native countries, during a long series of generations. I afterwards found that this same idea had long ago occurred to Dr. Wells. (56. See a paper read before the Royal Soc. in 1813, and published in his Essays in 1818. I have given an account of Dr. Wells' views in the Historical Sketch (p. xvi.) to my 'Origin of Species.' Various cases of colour correlated with constitutional peculiarities are given in my 'Variation of Animals and Plants under Domestication,' vol. ii. pp. 227, 335.) It has long been known that negroes, and even mulattoes, are almost completely exempt from the yellow-fever, so destructive in tropical America. (57. See, for instance, Nott and Gliddon, 'Types of Mankind,' p. 68.) They likewise escape to a large extent the fatal intermittent fevers, that prevail along at least 2600 miles of the shores of Africa, and which annually cause one-fifth of the white settlers to die, and another fifth to return home invalided. (58. Major Tulloch, in a paper read before the Statistical Society, April 20, 1840, and given in the 'Athenaeum,' 1840, p. 353.) This immunity in the negro seems to be partly inherent, depending on some unknown peculiarity of constitution, and partly the result of acclimatisation. Pouchet (59. 'The Plurality of the Human Race' (translat.), 1864, p. 60.) states that the negro regiments recruited near the Soudan, and borrowed from the Viceroy of Egypt for the Mexican war, escaped the yellow-fever almost equally with the negroes originally brought from various parts of Africa and accustomed to the climate of the West Indies. That acclimatisation plays a part, is shewn by the many cases in which negroes have become somewhat liable to tropical fevers, after having resided for some time in a colder climate. (60. Quatrefages, 'Unité de l'Espèce Humaine,' 1861, p. 205. Waitz, 'Introduction to Anthropology,' translat., vol. i. 1863, p. 124. Livingstone gives analogous cases in his 'Travels.') The nature of the climate under which the white races have long resided, likewise has some influence on them; for during the fearful epidemic of yellow fever in Demerara during 1837, Dr. Blair found that the death-rate of the immigrants was proportional to the latitude of the country whence they had come. With the negro the immunity, as far as it is the result of acclimatisation, implies exposure during a prodigious length of time; for the aborigines of tropical America who have resided there from time immemorial, are not exempt from yellow fever; and the Rev. H.B. Tristram states, that there are districts in Northern Africa which the native inhabitants are compelled annually to leave, though the negroes can remain with safety. That the immunity of the negro is in any degree correlated with the colour of his skin is a mere conjecture: it may be correlated with some difference in his blood, nervous system, or other tissues. Nevertheless, from the facts above alluded to, and from some connection apparently existing between complexion and a tendency to consumption, the conjecture seemed to me not improbable. Consequently I endeavoured, with but little success (61. In the spring of 1862 I obtained permission from the Director-General of the Medical department of the Army, to transmit to the surgeons of the various regiments on foreign service a blank table, with the following appended remarks, but I have received no returns. "As several well-marked cases have been recorded with our domestic animals of a relation between the colour of the dermal appendages and the constitution; and it being notorious that there is some limited degree of relation between the colour of the races of man and the climate inhabited by them; the following investigation seems worth consideration. Namely, whether there is any relation in Europeans between the colour of their hair, and their liability to the diseases of tropical countries. If the surgeons of the several regiments, when stationed in unhealthy tropical districts, would be so good as first to count, as a standard of comparison, how many men, in the force whence the sick are drawn, have dark and light-coloured hair, and hair of intermediate or doubtful tints; and if a similar account were kept by the same medical gentlemen, of all the men who suffered from malarious and yellow fevers, or from dysentery, it would soon be apparent, after some thousand cases had been tabulated, whether there exists any relation between the colour of the hair and constitutional liability to tropical diseases. Perhaps no such relation would be discovered, but the investigation is well worth making. In case any positive result were obtained, it might be of some practical use in selecting men for any particular service. Theoretically the result would be of high interest, as indicating one means by which a race of men inhabiting from a remote period an unhealthy tropical climate, might have become dark-coloured by the better preservation of dark-haired or dark-complexioned individuals during a long succession of generations."), to ascertain how far it holds good. The late Dr. Daniell, who had long lived on the West Coast of Africa, told me that he did not believe in any such relation. He was himself unusually fair, and had withstood the climate in a wonderful manner. When he first arrived as a boy on the coast, an old and experienced negro chief predicted from his appearance that this would prove the case. Dr. Nicholson, of Antigua, after having attended to this subject, writes to me that dark-coloured Europeans escape the yellow fever more than those that are light-coloured. Mr. J.M. Harris altogether denies that Europeans with dark hair withstand a hot climate better than other men: on the contrary, experience has taught him in making a selection of men for service on the coast of Africa, to choose those with red hair. (62. 'Anthropological Review,' Jan. 1866, p. xxi. Dr. Sharpe also says, with respect to India ('Man a Special Creation,' 1873, p. 118), "that it has been noticed by some medical officers that Europeans with light hair and florid complexions suffer less from diseases of tropical countries than persons with dark hair and sallow complexions; and, so far as I know, there appear to be good grounds for this remark." On the other hand, Mr. Heddle, of Sierra Leone, "who has had more clerks killed under him than any other man," by the climate of the West African Coast (W. Reade, 'African Sketch Book,' vol. ii. p. 522), holds a directly opposite view, as does Capt. Burton.) As far, therefore, as these slight indications go, there seems no foundation for the hypothesis, that blackness has resulted from the darker and darker individuals having survived better during long exposure to fever-generating miasma. Dr. Sharpe remarks (63. 'Man a Special Creation,' 1873, p. 119.), that a tropical sun, which burns and blisters a white skin, does not injure a black one at all; and, as he adds, this is not due to habit in the individual, for children only six or eight months old are often carried about naked, and are not affected. I have been assured by a medical man, that some years ago during each summer, but not during the winter, his hands became marked with light brown patches, like, although larger than freckles, and that these patches were never affected by sun-burning, whilst the white parts of his skin have on several occasions been much inflamed and blistered. With the lower animals there is, also, a constitutional difference in liability to the action of the sun between those parts of the skin clothed with white hair and other parts. (64. 'Variation of Animals and Plants under Domestication,' vol. ii. pp. 336, 337.) Whether the saving of the skin from being thus burnt is of sufficient importance to account for a dark tint having been gradually acquired by man through natural selection, I am unable to judge. If it be so, we should have to assume that the natives of tropical America have lived there for a much shorter time than the Negroes in Africa, or the Papuans in the southern parts of the Malay archipelago, just as the lighter-coloured Hindoos have resided in India for a shorter time than the darker aborigines of the central and southern parts of the peninsula. Although with our present knowledge we cannot account for the differences of colour in the races of man, through any advantage thus gained, or from the direct action of climate; yet we must not quite ignore the latter agency, for there is good reason to believe that some inherited effect is thus produced. (65. See, for instance, Quatrefages ('Revue des Cours Scientifiques,' Oct. 10, 1868, p. 724) on the effects of residence in Abyssinia and Arabia, and other analogous cases. Dr. Rolle ('Der Mensch, seine Abstammung,' etc., 1865, s. 99) states, on the authority of Khanikof, that the greater number of German families settled in Georgia, have acquired in the course of two generations dark hair and eyes. Mr. D. Forbes informs me that the Quichuas in the Andes vary greatly in colour, according to the position of the valleys inhabited by them.) We have seen in the second chapter that the conditions of life affect the development of the bodily frame in a direct manner, and that the effects are transmitted. Thus, as is generally admitted, the European settlers in the United States undergo a slight but extraordinary rapid change of appearance. Their bodies and limbs become elongated; and I hear from Col. Bernys that during the late war in the United States, good evidence was afforded of this fact by the ridiculous appearance presented by the German regiments, when dressed in ready-made clothes manufactured for the American market, and which were much too long for the men in every way. There is, also, a considerable body of evidence shewing that in the Southern States the house-slaves of the third generation present a markedly different appearance from the field-slaves. (66. Harlan, 'Medical Researches,' p. 532. Quatrefages ('Unité de l'Espèce Humaine,' 1861, p. 128) has collected much evidence on this head.) If, however, we look to the races of man as distributed over the world, we must infer that their characteristic differences cannot be accounted for by the direct action of different conditions of life, even after exposure to them for an enormous period of time. The Esquimaux live exclusively on animal food; they are clothed in thick fur, and are exposed to intense cold and to prolonged darkness; yet they do not differ in any extreme degree from the inhabitants of Southern China, who live entirely on vegetable food, and are exposed almost naked to a hot, glaring climate. The unclothed Fuegians live on the marine productions of their inhospitable shores; the Botocudos of Brazil wander about the hot forests of the interior and live chiefly on vegetable productions; yet these tribes resemble each other so closely that the Fuegians on board the "Beagle" were mistaken by some Brazilians for Botocudos. The Botocudos again, as well as the other inhabitants of tropical America, are wholly different from the Negroes who inhabit the opposite shores of the Atlantic, are exposed to a nearly similar climate, and follow nearly the same habits of life. Nor can the differences between the races of man be accounted for by the inherited effects of the increased or decreased use of parts, except to a quite insignificant degree. Men who habitually live in canoes, may have their legs somewhat stunted; those who inhabit lofty regions may have their chests enlarged; and those who constantly use certain sense-organs may have the cavities in which they are lodged somewhat increased in size, and their features consequently a little modified. With civilised nations, the reduced size of the jaws from lessened use--the habitual play of different muscles serving to express different emotions--and the increased size of the brain from greater intellectual activity, have together produced a considerable effect on their general appearance when compared with savages. (67. See Prof. Schaaffhausen, translat., in 'Anthropological Review,' Oct. 1868, p. 429.) Increased bodily stature, without any corresponding increase in the size of the brain, may (judging from the previously adduced case of rabbits), have given to some races an elongated skull of the dolichocephalic type. Lastly, the little-understood principle of correlated development has sometimes come into action, as in the case of great muscular development and strongly projecting supra-orbital ridges. The colour of the skin and hair are plainly correlated, as is the texture of the hair with its colour in the Mandans of North America. (68. Mr. Catlin states ('N. American Indians,' 3rd ed., 1842, vol. i. p. 49) that in the whole tribe of the Mandans, about one in ten or twelve of the members, of all ages and both sexes, have bright silvery grey hair, which is hereditary. Now this hair is as coarse and harsh as that of a horse's mane, whilst the hair of other colours is fine and soft.) The colour also of the skin, and the odour emitted by it, are likewise in some manner connected. With the breeds of sheep the number of hairs within a given space and the number of excretory pores are related. (69. On the odour of the skin, Godron, 'Sur l'Espèce,' tom. ii. p. 217. On the pores in the skin, Dr. Wilckens, 'Die Aufgaben der Landwirth. Zootechnik,' 1869, s. 7.) If we may judge from the analogy of our domesticated animals, many modifications of structure in man probably come under this principle of correlated development. We have now seen that the external characteristic differences between the races of man cannot be accounted for in a satisfactory manner by the direct action of the conditions of life, nor by the effects of the continued use of parts, nor through the principle of correlation. We are therefore led to enquire whether slight individual differences, to which man is eminently liable, may not have been preserved and augmented during a long series of generations through natural selection. But here we are at once met by the objection that beneficial variations alone can be thus preserved; and as far as we are enabled to judge, although always liable to err on this head, none of the differences between the races of man are of any direct or special service to him. The intellectual and moral or social faculties must of course be excepted from this remark. The great variability of all the external differences between the races of man, likewise indicates that they cannot be of much importance; for if important, they would long ago have been either fixed and preserved, or eliminated. In this respect man resembles those forms, called by naturalists protean or polymorphic, which have remained extremely variable, owing, as it seems, to such variations being of an indifferent nature, and to their having thus escaped the action of natural selection. We have thus far been baffled in all our attempts to account for the differences between the races of man; but there remains one important agency, namely Sexual Selection, which appears to have acted powerfully on man, as on many other animals. I do not intend to assert that sexual selection will account for all the differences between the races. An unexplained residuum is left, about which we can only say, in our ignorance, that as individuals are continually born with, for instance, heads a little rounder or narrower, and with noses a little longer or shorter, such slight differences might become fixed and uniform, if the unknown agencies which induced them were to act in a more constant manner, aided by long-continued intercrossing. Such variations come under the provisional class, alluded to in our second chapter, which for want of a better term are often called spontaneous. Nor do I pretend that the effects of sexual selection can be indicated with scientific precision; but it can be shewn that it would be an inexplicable fact if man had not been modified by this agency, which appears to have acted powerfully on innumerable animals. It can further be shewn that the differences between the races of man, as in colour, hairiness, form of features, etc., are of a kind which might have been expected to come under the influence of sexual selection. But in order to treat this subject properly, I have found it necessary to pass the whole animal kingdom in review. I have therefore devoted to it the Second Part of this work. At the close I shall return to man, and, after attempting to shew how far he has been modified through sexual selection, will give a brief summary of the chapters in this First Part. NOTE ON THE RESEMBLANCES AND DIFFERENCES IN THE STRUCTURE AND THE DEVELOPMENT OF THE BRAIN IN MAN AND APES BY PROFESSOR HUXLEY, F.R.S. The controversy respecting the nature and the extent of the differences in the structure of the brain in man and the apes, which arose some fifteen years ago, has not yet come to an end, though the subject matter of the dispute is, at present, totally different from what it was formerly. It was originally asserted and re-asserted, with singular pertinacity, that the brain of all the apes, even the highest, differs from that of man, in the absence of such conspicuous structures as the posterior lobes of the cerebral hemispheres, with the posterior cornu of the lateral ventricle and the hippocampus minor, contained in those lobes, which are so obvious in man. But the truth that the three structures in question are as well developed in apes' as in human brains, or even better; and that it is characteristic of all the Primates (if we exclude the Lemurs) to have these parts well developed, stands at present on as secure a basis as any proposition in comparative anatomy. Moreover, it is admitted by every one of the long series of anatomists who, of late years, have paid special attention to the arrangement of the complicated sulci and gyri which appear upon the surface of the cerebral hemispheres in man and the higher apes, that they are disposed after the very same pattern in him, as in them. Every principal gyrus and sulcus of a chimpanzee's brain is clearly represented in that of a man, so that the terminology which applies to the one answers for the other. On this point there is no difference of opinion. Some years since, Professor Bischoff published a memoir (70. 'Die Grosshirn-Windungen des Menschen;' 'Abhandlungen der K. Bayerischen Akademie,' B. x. 1868.) on the cerebral convolutions of man and apes; and as the purpose of my learned colleague was certainly not to diminish the value of the differences between apes and men in this respect, I am glad to make a citation from him. "That the apes, and especially the orang, chimpanzee and gorilla, come very close to man in their organisation, much nearer than to any other animal, is a well known fact, disputed by nobody. Looking at the matter from the point of view of organisation alone, no one probably would ever have disputed the view of Linnaeus, that man should be placed, merely as a peculiar species, at the head of the mammalia and of those apes. Both shew, in all their organs, so close an affinity, that the most exact anatomical investigation is needed in order to demonstrate those differences which really exist. So it is with the brains. The brains of man, the orang, the chimpanzee, the gorilla, in spite of all the important differences which they present, come very close to one another" (loc. cit. p. 101). There remains, then, no dispute as to the resemblance in fundamental characters, between the ape's brain and man's: nor any as to the wonderfully close similarity between the chimpanzee, orang and man, in even the details of the arrangement of the gyri and sulci of the cerebral hemispheres. Nor, turning to the differences between the brains of the highest apes and that of man, is there any serious question as to the nature and extent of these differences. It is admitted that the man's cerebral hemispheres are absolutely and relatively larger than those of the orang and chimpanzee; that his frontal lobes are less excavated by the upward protrusion of the roof of the orbits; that his gyri and sulci are, as a rule, less symmetrically disposed, and present a greater number of secondary plications. And it is admitted that, as a rule, in man, the temporo-occipital or "external perpendicular" fissure, which is usually so strongly marked a feature of the ape's brain is but faintly marked. But it is also clear, that none of these differences constitutes a sharp demarcation between the man's and the ape's brain. In respect to the external perpendicular fissure of Gratiolet, in the human brain for instance, Professor Turner remarks: (71. 'Convolutions of the Human Cerebrum Topographically Considered,' 1866, p. 12.) "In some brains it appears simply as an indentation of the margin of the hemisphere, but, in others, it extends for some distance more or less transversely outwards. I saw it in the right hemisphere of a female brain pass more than two inches outwards; and on another specimen, also the right hemisphere, it proceeded for four-tenths of an inch outwards, and then extended downwards, as far as the lower margin of the outer surface of the hemisphere. The imperfect definition of this fissure in the majority of human brains, as compared with its remarkable distinctness in the brain of most Quadrumana, is owing to the presence, in the former, of certain superficial, well marked, secondary convolutions which bridge it over and connect the parietal with the occipital lobe. The closer the first of these bridging gyri lies to the longitudinal fissure, the shorter is the external parieto-occipital fissure" (loc. cit. p. 12). The obliteration of the external perpendicular fissure of Gratiolet, therefore, is not a constant character of the human brain. On the other hand, its full development is not a constant character of the higher ape's brain. For, in the chimpanzee, the more or less extensive obliteration of the external perpendicular sulcus by "bridging convolutions," on one side or the other, has been noted over and over again by Prof. Rolleston, Mr. Marshall, M. Broca and Professor Turner. At the conclusion of a special paper on this subject the latter writes: (72. Notes more especially on the bridging convolutions in the Brain of the Chimpanzee, 'Proceedings of the Royal Society of Edinburgh,' 1865-6.) "The three specimens of the brain of a chimpanzee, just described, prove, that the generalisation which Gratiolet has attempted to draw of the complete absence of the first connecting convolution and the concealment of the second, as essentially characteristic features in the brain of this animal, is by no means universally applicable. In only one specimen did the brain, in these particulars, follow the law which Gratiolet has expressed. As regards the presence of the superior bridging convolution, I am inclined to think that it has existed in one hemisphere, at least, in a majority of the brains of this animal which have, up to this time, been figured or described. The superficial position of the second bridging convolution is evidently less frequent, and has as yet, I believe, only been seen in the brain (A) recorded in this communication. The asymmetrical arrangement in the convolutions of the two hemispheres, which previous observers have referred to in their descriptions, is also well illustrated in these specimens" (pp. 8, 9). Even were the presence of the temporo-occipital, or external perpendicular, sulcus, a mark of distinction between the higher apes and man, the value of such a distinctive character would be rendered very doubtful by the structure of the brain in the Platyrrhine apes. In fact, while the temporo-occipital is one of the most constant of sulci in the Catarrhine, or Old World, apes, it is never very strongly developed in the New World apes; it is absent in the smaller Platyrrhini; rudimentary in Pithecia (73. Flower, 'On the Anatomy of Pithecia Monachus,' 'Proceedings of the Zoological Society,' 1862.); and more or less obliterated by bridging convolutions in Ateles. A character which is thus variable within the limits of a single group can have no great taxonomic value. It is further established, that the degree of asymmetry of the convolution of the two sides in the human brain is subject to much individual variation; and that, in those individuals of the Bushman race who have been examined, the gyri and sulci of the two hemispheres are considerably less complicated and more symmetrical than in the European brain, while, in some individuals of the chimpanzee, their complexity and asymmetry become notable. This is particularly the case in the brain of a young male chimpanzee figured by M. Broca. ('L'ordre des Primates,' p. 165, fig. 11.) Again, as respects the question of absolute size, it is established that the difference between the largest and the smallest healthy human brain is greater than the difference between the smallest healthy human brain and the largest chimpanzee's or orang's brain. Moreover, there is one circumstance in which the orang's and chimpanzee's brains resemble man's, but in which they differ from the lower apes, and that is the presence of two corpora candicantia--the Cynomorpha having but one. In view of these facts I do not hesitate in this year 1874, to repeat and insist upon the proposition which I enunciated in 1863: (74. 'Man's Place in Nature,' p. 102.) "So far as cerebral structure goes, therefore, it is clear that man differs less from the chimpanzee or the orang, than these do even from the monkeys, and that the difference between the brain of the chimpanzee and of man is almost insignificant when compared with that between the chimpanzee brain and that of a Lemur." In the paper to which I have referred, Professor Bischoff does not deny the second part of this statement, but he first makes the irrelevant remark that it is not wonderful if the brains of an orang and a Lemur are very different; and secondly, goes on to assert that, "If we successively compare the brain of a man with that of an orang; the brain of this with that of a chimpanzee; of this with that of a gorilla, and so on of a Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix, Lemur, Stenops, Hapale, we shall not meet with a greater, or even as great a, break in the degree of development of the convolutions, as we find between the brain of a man and that of an orang or chimpanzee." To which I reply, firstly, that whether this assertion be true or false, it has nothing whatever to do with the proposition enunciated in 'Man's Place in Nature,' which refers not to the development of the convolutions alone, but to the structure of the whole brain. If Professor Bischoff had taken the trouble to refer to p. 96 of the work he criticises, in fact, he would have found the following passage: "And it is a remarkable circumstance that though, so far as our present knowledge extends, there IS one true structural break in the series of forms of Simian brains, this hiatus does not lie between man and the manlike apes, but between the lower and the lowest Simians, or in other words, between the Old and New World apes and monkeys and the Lemurs. Every Lemur which has yet been examined, in fact, has its cerebellum partially visible from above; and its posterior lobe, with the contained posterior cornu and hippocampus minor, more or less rudimentary. Every marmoset, American monkey, Old World monkey, baboon or manlike ape, on the contrary, has its cerebellum entirely hidden, posteriorly, by the cerebral lobes, and possesses a large posterior cornu with a well-developed hippocampus minor." This statement was a strictly accurate account of what was known when it was made; and it does not appear to me to be more than apparently weakened by the subsequent discovery of the relatively small development of the posterior lobes in the Siamang and in the Howling monkey. Notwithstanding the exceptional brevity of the posterior lobes in these two species, no one will pretend that their brains, in the slightest degree, approach those of the Lemurs. And if, instead of putting Hapale out of its natural place, as Professor Bischoff most unaccountably does, we write the series of animals he has chosen to mention as follows: Homo, Pithecus, Troglodytes, Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the great break in this series lies between Hapale and Lemur, and that this break is considerably greater than that between any other two terms of that series. Professor Bischoff ignores the fact that long before he wrote, Gratiolet had suggested the separation of the Lemurs from the other Primates on the very ground of the difference in their cerebral characters; and that Professor Flower had made the following observations in the course of his description of the brain of the Javan Loris: (75. 'Transactions of the Zoological Society,' vol. v. 1862.) "And it is especially remarkable that, in the development of the posterior lobes, there is no approximation to the Lemurine, short hemisphered brain, in those monkeys which are commonly supposed to approach this family in other respects, viz. the lower members of the Platyrrhine group." So far as the structure of the adult brain is concerned, then, the very considerable additions to our knowledge, which have been made by the researches of so many investigators, during the past ten years, fully justify the statement which I made in 1863. But it has been said, that, admitting the similarity between the adult brains of man and apes, they are nevertheless, in reality, widely different, because they exhibit fundamental differences in the mode of their development. No one would be more ready than I to admit the force of this argument, if such fundamental differences of development really exist. But I deny that they do exist. On the contrary, there is a fundamental agreement in the development of the brain in men and apes. Gratiolet originated the statement that there is a fundamental difference in the development of the brains of apes and that of man--consisting in this; that, in the apes, the sulci which first make their appearance are situated on the posterior region of the cerebral hemispheres, while, in the human foetus, the sulci first become visible on the frontal lobes. (76. Chez tous les singes, les plis postérieurs se developpent les premiers; les plis antérieurs se developpent plus tard, aussi la vertèbre occipitale et la parietale sont-elles relativement tres-grandes chez le foetus. L'Homme présente une exception remarquable quant a l'époque de l'apparition des plis frontaux, qui sont les premiers indiqués; mais le développement general du lobe frontal, envisagé seulement par rapport a son volume, suit les mêmes lois que dans les singes: Gratiolet, 'Mémoire sur les plis cérèbres de l'Homme et des Primateaux,' p. 39, Tab. iv, fig. 3.) This general statement is based upon two observations, the one of a Gibbon almost ready to be born, in which the posterior gyri were "well developed," while those of the frontal lobes were "hardly indicated" (77. Gratiolet's words are (loc. cit. p. 39): "Dans le foetus dont il s'agit les plis cérébraux posterieurs sont bien developpés, tandis que les plis du lobe frontal sont a peine indiqués." The figure, however (Pl. iv, fig. 3), shews the fissure of Rolando, and one of the frontal sulci plainly enough. Nevertheless, M. Alix, in his 'Notice sur les travaux anthropologiques de Gratiolet' ('Mem. de la Societé d'Anthropologie de Paris,' 1868, page 32), writes thus: "Gratiolet a eu entre les mains le cerveau d'un foetus de Gibbon, singe eminemment supérieur, et tellement rapproché de l'orang, que des naturalistes tres-compétents l'ont rangé parmi les anthropoides. M. Huxley, par exemple, n'hesite pas sur ce point. Eh bien, c'est sur le cerveau d'un foetus de Gibbon que Gratiolet a vu LES CIRCONVOLUTIONS DU LOBE TEMPORO-SPHENOIDAL D�J� DEVELOPP�ES LORSQU'IL N'EXISTENT PAS ENCORE DE PLIS SUR LE LOBE FRONTAL. Il etait donc bien autorisé a dire que, chez l'homme les circonvolutions apparaissent d'a en w, tandis que chez les singes elles se developpent d'w en a."), and the other of a human foetus at the 22nd or 23rd week of uterogestation, in which Gratiolet notes that the insula was uncovered, but that nevertheless "des incisures sement de lobe anterieur, une scissure peu profonde indique la separation du lobe occipital, tres-reduit, d'ailleurs dès cette époque. Le reste de la surface cérébrale est encore absolument lisse." Three views of this brain are given in Plate II, figs. 1, 2, 3, of the work cited, shewing the upper, lateral and inferior views of the hemispheres, but not the inner view. It is worthy of note that the figure by no means bears out Gratiolet's description, inasmuch as the fissure (antero-temporal) on the posterior half of the face of the hemisphere is more marked than any of those vaguely indicated in the anterior half. If the figure is correct, it in no way justifies Gratiolet's conclusion: "Il y a donc entre ces cerveaux [those of a Callithrix and of a Gibbon] et celui du foetus humain une différence fondamental. Chez celui-ci, longtemps avant que les plis temporaux apparaissent, les plis frontaux, ESSAYENT d'exister." Since Gratiolet's time, however, the development of the gyri and sulci of the brain has been made the subject of renewed investigation by Schmidt, Bischoff, Pansch (78. 'Ueber die typische Anordnung der Furchen und Windungen auf den Grosshirn-Hemisphären des Menschen und der Affen,' 'Archiv für Anthropologie,' iii. 1868.), and more particularly by Ecker (79. 'Zur Entwicklungs Geschichte der Furchen und Windungen der Grosshirn-Hemisphären im Foetus des Menschen,' 'Archiv für Anthropologie,' iii. 1868.), whose work is not only the latest, but by far the most complete, memoir on the subject. The final results of their inquiries may be summed up as follows:-- 1. In the human foetus, the sylvian fissure is formed in the course of the third month of uterogestation. In this, and in the fourth month, the cerebral hemispheres are smooth and rounded (with the exception of the sylvian depression), and they project backwards far beyond the cerebellum. 2. The sulci, properly so called, begin to appear in the interval between the end of the fourth and the beginning of the sixth month of foetal life, but Ecker is careful to point out that, not only the time, but the order, of their appearance is subject to considerable individual variation. In no case, however, are either the frontal or the temporal sulci the earliest. The first which appears, in fact, lies on the inner face of the hemisphere (whence doubtless Gratiolet, who does not seem to have examined that face in his foetus, overlooked it), and is either the internal perpendicular (occipito-parietal), or the calcarine sulcus, these two being close together and eventually running into one another. As a rule the occipito-parietal is the earlier of the two. 3. At the latter part of this period, another sulcus, the "posterio-parietal," or "Fissure of Rolando" is developed, and it is followed, in the course of the sixth month, by the other principal sulci of the frontal, parietal, temporal and occipital lobes. There is, however, no clear evidence that one of these constantly appears before the other; and it is remarkable that, in the brain at the period described and figured by Ecker (loc. cit. pp. 212-213, Taf. II, figs. 1, 2, 3, 4), the antero-temporal sulcus (scissure parallele) so characteristic of the ape's brain, is as well, if not better developed than the fissure of Rolando, and is much more marked than the proper frontal sulci. Taking the facts as they now stand, it appears to me that the order of the appearance of the sulci and gyri in the foetal human brain is in perfect harmony with the general doctrine of evolution, and with the view that man has been evolved from some ape-like form; though there can be no doubt that form was, in many respects, different from any member of the Primates now living. Von Baer taught us, half a century ago, that, in the course of their development, allied animals put on at first, the characters of the greater groups to which they belong, and, by degrees, assume those which restrict them within the limits of their family, genus, and species; and he proved, at the same time, that no developmental stage of a higher animal is precisely similar to the adult condition of any lower animal. It is quite correct to say that a frog passes through the condition of a fish, inasmuch as at one period of its life the tadpole has all the characters of a fish, and if it went no further, would have to be grouped among fishes. But it is equally true that a tadpole is very different from any known fish. In like manner, the brain of a human foetus, at the fifth month, may correctly be said to be, not only the brain of an ape, but that of an Arctopithecine or marmoset-like ape; for its hemispheres, with their great posterior lobster, and with no sulci but the sylvian and the calcarine, present the characteristics found only in the group of the Arctopithecine Primates. But it is equally true, as Gratiolet remarks, that, in its widely open sylvian fissure, it differs from the brain of any actual marmoset. No doubt it would be much more similar to the brain of an advanced foetus of a marmoset. But we know nothing whatever of the development of the brain in the marmosets. In the Platyrrhini proper, the only observation with which I am acquainted is due to Pansch, who found in the brain of a foetal Cebus Apella, in addition to the sylvian fissure and the deep calcarine fissure, only a very shallow antero-temporal fissure (scissure parallele of Gratiolet). Now this fact, taken together with the circumstance that the antero-temporal sulcus is present in such Platyrrhini as the Saimiri, which present mere traces of sulci on the anterior half of the exterior of the cerebral hemispheres, or none at all, undoubtedly, so far as it goes, affords fair evidence in favour of Gratiolet's hypothesis, that the posterior sulci appear before the anterior, in the brains of the Platyrrhini. But, it by no means follows, that the rule which may hold good for the Platyrrhini extends to the Catarrhini. We have no information whatever respecting the development of the brain in the Cynomorpha; and, as regards the Anthropomorpha, nothing but the account of the brain of the Gibbon, near birth, already referred to. At the present moment there is not a shadow of evidence to shew that the sulci of a chimpanzee's, or orang's, brain do not appear in the same order as a man's. Gratiolet opens his preface with the aphorism: "Il est dangereux dans les sciences de conclure trop vite." I fear he must have forgotten this sound maxim by the time he had reached the discussion of the differences between men and apes, in the body of his work. No doubt, the excellent author of one of the most remarkable contributions to the just understanding of the mammalian brain which has ever been made, would have been the first to admit the insufficiency of his data had he lived to profit by the advance of inquiry. The misfortune is that his conclusions have been employed by persons incompetent to appreciate their foundation, as arguments in favour of obscurantism. (80. For example, M. l'Abbe Lecomte in his terrible pamphlet, 'Le Darwinisme et l'origine de l'Homme,' 1873.) But it is important to remark that, whether Gratiolet was right or wrong in his hypothesis respecting the relative order of appearance of the temporal and frontal sulci, the fact remains; that before either temporal or frontal sulci, appear, the foetal brain of man presents characters which are found only in the lowest group of the Primates (leaving out the Lemurs); and that this is exactly what we should expect to be the case, if man has resulted from the gradual modification of the same form as that from which the other Primates have sprung. PART II. SEXUAL SELECTION. CHAPTER VIII. PRINCIPLES OF SEXUAL SELECTION. Secondary sexual characters--Sexual selection--Manner of action--Excess of males--Polygamy--The male alone generally modified through sexual selection--Eagerness of the male--Variability of the male--Choice exerted by the female--Sexual compared with natural selection--Inheritance, at corresponding periods of life, at corresponding seasons of the year, and as limited by sex--Relations between the several forms of inheritance--Causes why one sex and the young are not modified through sexual selection--Supplement on the proportional numbers of the two sexes throughout the animal kingdom--The proportion of the sexes in relation to natural selection. With animals which have their sexes separated, the males necessarily differ from the females in their organs of reproduction; and these are the primary sexual characters. But the sexes often differ in what Hunter has called secondary sexual characters, which are not directly connected with the act of reproduction; for instance, the male possesses certain organs of sense or locomotion, of which the female is quite destitute, or has them more highly-developed, in order that he may readily find or reach her; or again the male has special organs of prehension for holding her securely. These latter organs, of infinitely diversified kinds, graduate into those which are commonly ranked as primary, and in some cases can hardly be distinguished from them; we see instances of this in the complex appendages at the apex of the abdomen in male insects. Unless indeed we confine the term "primary" to the reproductive glands, it is scarcely possible to decide which ought to be called primary and which secondary. The female often differs from the male in having organs for the nourishment or protection of her young, such as the mammary glands of mammals, and the abdominal sacks of the marsupials. In some few cases also the male possesses similar organs, which are wanting in the female, such as the receptacles for the ova in certain male fishes, and those temporarily developed in certain male frogs. The females of most bees are provided with a special apparatus for collecting and carrying pollen, and their ovipositor is modified into a sting for the defence of the larvae and the community. Many similar cases could be given, but they do not here concern us. There are, however, other sexual differences quite unconnected with the primary reproductive organs, and it is with these that we are more especially concerned--such as the greater size, strength, and pugnacity of the male, his weapons of offence or means of defence against rivals, his gaudy colouring and various ornaments, his power of song, and other such characters. Besides the primary and secondary sexual differences, such as the foregoing, the males and females of some animals differ in structures related to different habits of life, and not at all, or only indirectly, to the reproductive functions. Thus the females of certain flies (Culicidae and Tabanidae) are blood-suckers, whilst the males, living on flowers, have mouths destitute of mandibles. (1. Westwood, 'Modern Classification of Insects,' vol. ii. 1840, p. 541. For the statement about Tanais, mentioned below, I am indebted to Fritz Muller.) The males of certain moths and of some crustaceans (e.g. Tanais) have imperfect, closed mouths, and cannot feed. The complemental males of certain Cirripedes live like epiphytic plants either on the female or the hermaphrodite form, and are destitute of a mouth and of prehensile limbs. In these cases it is the male which has been modified, and has lost certain important organs, which the females possess. In other cases it is the female which has lost such parts; for instance, the female glow-worm is destitute of wings, as also are many female moths, some of which never leave their cocoons. Many female parasitic crustaceans have lost their natatory legs. In some weevil-beetles (Curculionidae) there is a great difference between the male and female in the length of the rostrum or snout (2. Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 309.); but the meaning of this and of many analogous differences, is not at all understood. Differences of structure between the two sexes in relation to different habits of life are generally confined to the lower animals; but with some few birds the beak of the male differs from that of the female. In the Huia of New Zealand the difference is wonderfully great, and we hear from Dr. Buller (3. 'Birds of New Zealand,' 1872, p. 66.) that the male uses his strong beak in chiselling the larvae of insects out of decayed wood, whilst the female probes the softer parts with her far longer, much curved and pliant beak: and thus they mutually aid each other. In most cases, differences of structure between the sexes are more or less directly connected with the propagation of the species: thus a female, which has to nourish a multitude of ova, requires more food than the male, and consequently requires special means for procuring it. A male animal, which lives for a very short time, might lose its organs for procuring food through disuse, without detriment; but he would retain his locomotive organs in a perfect state, so that he might reach the female. The female, on the other hand, might safely lose her organs for flying, swimming, or walking, if she gradually acquired habits which rendered such powers useless. We are, however, here concerned only with sexual selection. This depends on the advantage which certain individuals have over others of the same sex and species solely in respect of reproduction. When, as in the cases above mentioned, the two sexes differ in structure in relation to different habits of life, they have no doubt been modified through natural selection, and by inheritance limited to one and the same sex. So again the primary sexual organs, and those for nourishing or protecting the young, come under the same influence; for those individuals which generated or nourished their offspring best, would leave, ceteris paribus, the greatest number to inherit their superiority; whilst those which generated or nourished their offspring badly, would leave but few to inherit their weaker powers. As the male has to find the female, he requires organs of sense and locomotion, but if these organs are necessary for the other purposes of life, as is generally the case, they will have been developed through natural selection. When the male has found the female, he sometimes absolutely requires prehensile organs to hold her; thus Dr. Wallace informs me that the males of certain moths cannot unite with the females if their tarsi or feet are broken. The males of many oceanic crustaceans, when adult, have their legs and antennae modified in an extraordinary manner for the prehension of the female; hence we may suspect that it is because these animals are washed about by the waves of the open sea, that they require these organs in order to propagate their kind, and if so, their development has been the result of ordinary or natural selection. Some animals extremely low in the scale have been modified for this same purpose; thus the males of certain parasitic worms, when fully grown, have the lower surface of the terminal part of their bodies roughened like a rasp, and with this they coil round and permanently hold the females. (4. M. Perrier advances this case ('Revue Scientifique,' Feb. 1, 1873, p. 865) as one fatal to the belief in sexual election, inasmuch as he supposes that I attribute all the differences between the sexes to sexual selection. This distinguished naturalist, therefore, like so many other Frenchmen, has not taken the trouble to understand even the first principles of sexual selection. An English naturalist insists that the claspers of certain male animals could not have been developed through the choice of the female! Had I not met with this remark, I should not have thought it possible for any one to have read this chapter and to have imagined that I maintain that the choice of the female had anything to do with the development of the prehensile organs in the male.) When the two sexes follow exactly the same habits of life, and the male has the sensory or locomotive organs more highly developed than those of the female, it may be that the perfection of these is indispensable to the male for finding the female; but in the vast majority of cases, they serve only to give one male an advantage over another, for with sufficient time, the less well-endowed males would succeed in pairing with the females; and judging from the structure of the female, they would be in all other respects equally well adapted for their ordinary habits of life. Since in such cases the males have acquired their present structure, not from being better fitted to survive in the struggle for existence, but from having gained an advantage over other males, and from having transmitted this advantage to their male offspring alone, sexual selection must here have come into action. It was the importance of this distinction which led me to designate this form of selection as Sexual Selection. So again, if the chief service rendered to the male by his prehensile organs is to prevent the escape of the female before the arrival of other males, or when assaulted by them, these organs will have been perfected through sexual selection, that is by the advantage acquired by certain individuals over their rivals. But in most cases of this kind it is impossible to distinguish between the effects of natural and sexual selection. Whole chapters could be filled with details on the differences between the sexes in their sensory, locomotive, and prehensile organs. As, however, these structures are not more interesting than others adapted for the ordinary purposes of life I shall pass them over almost entirely, giving only a few instances under each class. There are many other structures and instincts which must have been developed through sexual selection--such as the weapons of offence and the means of defence of the males for fighting with and driving away their rivals--their courage and pugnacity--their various ornaments--their contrivances for producing vocal or instrumental music--and their glands for emitting odours, most of these latter structures serving only to allure or excite the female. It is clear that these characters are the result of sexual and not of ordinary selection, since unarmed, unornamented, or unattractive males would succeed equally well in the battle for life and in leaving a numerous progeny, but for the presence of better endowed males. We may infer that this would be the case, because the females, which are unarmed and unornamented, are able to survive and procreate their kind. Secondary sexual characters of the kind just referred to, will be fully discussed in the following chapters, as being in many respects interesting, but especially as depending on the will, choice, and rivalry of the individuals of either sex. When we behold two males fighting for the possession of the female, or several male birds displaying their gorgeous plumage, and performing strange antics before an assembled body of females, we cannot doubt that, though led by instinct, they know what they are about, and consciously exert their mental and bodily powers. Just as man can improve the breeds of his game-cocks by the selection of those birds which are victorious in the cockpit, so it appears that the strongest and most vigorous males, or those provided with the best weapons, have prevailed under nature, and have led to the improvement of the natural breed or species. A slight degree of variability leading to some advantage, however slight, in reiterated deadly contests would suffice for the work of sexual selection; and it is certain that secondary sexual characters are eminently variable. Just as man can give beauty, according to his standard of taste, to his male poultry, or more strictly can modify the beauty originally acquired by the parent species, can give to the Sebright bantam a new and elegant plumage, an erect and peculiar carriage--so it appears that female birds in a state of nature, have by a long selection of the more attractive males, added to their beauty or other attractive qualities. No doubt this implies powers of discrimination and taste on the part of the female which will at first appear extremely improbable; but by the facts to be adduced hereafter, I hope to be able to shew that the females actually have these powers. When, however, it is said that the lower animals have a sense of beauty, it must not be supposed that such sense is comparable with that of a cultivated man, with his multiform and complex associated ideas. A more just comparison would be between the taste for the beautiful in animals, and that in the lowest savages, who admire and deck themselves with any brilliant, glittering, or curious object. From our ignorance on several points, the precise manner in which sexual selection acts is somewhat uncertain. Nevertheless if those naturalists who already believe in the mutability of species, will read the following chapters, they will, I think, agree with me, that sexual selection has played an important part in the history of the organic world. It is certain that amongst almost all animals there is a struggle between the males for the possession of the female. This fact is so notorious that it would be superfluous to give instances. Hence the females have the opportunity of selecting one out of several males, on the supposition that their mental capacity suffices for the exertion of a choice. In many cases special circumstances tend to make the struggle between the males particularly severe. Thus the males of our migratory birds generally arrive at their places of breeding before the females, so that many males are ready to contend for each female. I am informed by Mr. Jenner Weir, that the bird-catchers assert that this is invariably the case with the nightingale and blackcap, and with respect to the latter he can himself confirm the statement. Mr. Swaysland of Brighton has been in the habit, during the last forty years, of catching our migratory birds on their first arrival, and he has never known the females of any species to arrive before their males. During one spring he shot thirty-nine males of Ray's wagtail (Budytes Raii) before he saw a single female. Mr. Gould has ascertained by the dissection of those snipes which arrive the first in this country, that the males come before the females. And the like holds good with most of the migratory birds of the United States. (5. J.A. Allen, on the 'Mammals and Winter Birds of Florida,' Bulletin of Comparative Zoology, Harvard College, p. 268.) The majority of the male salmon in our rivers, on coming up from the sea, are ready to breed before the females. So it appears to be with frogs and toads. Throughout the great class of insects the males almost always are the first to emerge from the pupal state, so that they generally abound for a time before any females can be seen. (6. Even with those plants in which the sexes are separate, the male flowers are generally mature before the female. As first shewn by C.K. Sprengel, many hermaphrodite plants are dichogamous; that is, their male and female organs are not ready at the same time, so that they cannot be self-fertilised. Now in such flowers, the pollen is in general matured before the stigma, though there are exceptional cases in which the female organs are beforehand.) The cause of this difference between the males and females in their periods of arrival and maturity is sufficiently obvious. Those males which annually first migrated into any country, or which in the spring were first ready to breed, or were the most eager, would leave the largest number of offspring; and these would tend to inherit similar instincts and constitutions. It must be borne in mind that it would have been impossible to change very materially the time of sexual maturity in the females, without at the same time interfering with the period of the production of the young--a period which must be determined by the seasons of the year. On the whole there can be no doubt that with almost all animals, in which the sexes are separate, there is a constantly recurrent struggle between the males for the possession of the females. Our difficulty in regard to sexual selection lies in understanding how it is that the males which conquer other males, or those which prove the most attractive to the females, leave a greater number of offspring to inherit their superiority than their beaten and less attractive rivals. Unless this result does follow, the characters which give to certain males an advantage over others, could not be perfected and augmented through sexual selection. When the sexes exist in exactly equal numbers, the worst-endowed males will (except where polygamy prevails), ultimately find females, and leave as many offspring, as well fitted for their general habits of life, as the best-endowed males. From various facts and considerations, I formerly inferred that with most animals, in which secondary sexual characters are well developed, the males considerably exceeded the females in number; but this is not by any means always true. If the males were to the females as two to one, or as three to two, or even in a somewhat lower ratio, the whole affair would be simple; for the better-armed or more attractive males would leave the largest number of offspring. But after investigating, as far as possible, the numerical proportion of the sexes, I do not believe that any great inequality in number commonly exists. In most cases sexual selection appears to have been effective in the following manner. Let us take any species, a bird for instance, and divide the females inhabiting a district into two equal bodies, the one consisting of the more vigorous and better-nourished individuals, and the other of the less vigorous and healthy. The former, there can be little doubt, would be ready to breed in the spring before the others; and this is the opinion of Mr. Jenner Weir, who has carefully attended to the habits of birds during many years. There can also be no doubt that the most vigorous, best-nourished and earliest breeders would on an average succeed in rearing the largest number of fine offspring. (7. Here is excellent evidence on the character of the offspring from an experienced ornithologist. Mr. J.A. Allen, in speaking ('Mammals and Winter Birds of E. Florida,' p. 229) of the later broods, after the accidental destruction of the first, says, that these "are found to be smaller and paler-coloured than those hatched earlier in the season. In cases where several broods are reared each year, as a general rule the birds of the earlier broods seem in all respects the most perfect and vigorous.") The males, as we have seen, are generally ready to breed before the females; the strongest, and with some species the best armed of the males, drive away the weaker; and the former would then unite with the more vigorous and better-nourished females, because they are the first to breed. (8. Hermann Müller has come to this same conclusion with respect to those female bees which are the first to emerge from the pupa each year. See his remarkable essay, 'Anwendung der Darwin'schen Lehre auf Bienen,' 'Verh. d. V. Jahrg.' xxix. p. 45.) Such vigorous pairs would surely rear a larger number of offspring than the retarded females, which would be compelled to unite with the conquered and less powerful males, supposing the sexes to be numerically equal; and this is all that is wanted to add, in the course of successive generations, to the size, strength and courage of the males, or to improve their weapons. But in very many cases the males which conquer their rivals, do not obtain possession of the females, independently of the choice of the latter. The courtship of animals is by no means so simple and short an affair as might be thought. The females are most excited by, or prefer pairing with, the more ornamented males, or those which are the best songsters, or play the best antics; but it is obviously probable that they would at the same time prefer the more vigorous and lively males, and this has in some cases been confirmed by actual observation. (9. With respect to poultry, I have received information, hereafter to be given, to this effect. Even with birds, such as pigeons, which pair for life, the female, as I hear from Mr. Jenner Weir, will desert her mate if he is injured or grows weak.) Thus the more vigorous females, which are the first to breed, will have the choice of many males; and though they may not always select the strongest or best armed, they will select those which are vigorous and well armed, and in other respects the most attractive. Both sexes, therefore, of such early pairs would as above explained, have an advantage over others in rearing offspring; and this apparently has sufficed during a long course of generations to add not only to the strength and fighting powers of the males, but likewise to their various ornaments or other attractions. In the converse and much rarer case of the males selecting particular females, it is plain that those which were the most vigorous and had conquered others, would have the freest choice; and it is almost certain that they would select vigorous as well as attractive females. Such pairs would have an advantage in rearing offspring, more especially if the male had the power to defend the female during the pairing-season as occurs with some of the higher animals, or aided her in providing for the young. The same principles would apply if each sex preferred and selected certain individuals of the opposite sex; supposing that they selected not only the more attractive, but likewise the more vigorous individuals. NUMERICAL PROPORTION OF THE TWO SEXES. I have remarked that sexual selection would be a simple affair if the males were considerably more numerous than the females. Hence I was led to investigate, as far as I could, the proportions between the two sexes of as many animals as possible; but the materials are scanty. I will here give only a brief abstract of the results, retaining the details for a supplementary discussion, so as not to interfere with the course of my argument. Domesticated animals alone afford the means of ascertaining the proportional numbers at birth; but no records have been specially kept for this purpose. By indirect means, however, I have collected a considerable body of statistics, from which it appears that with most of our domestic animals the sexes are nearly equal at birth. Thus 25,560 births of race-horses have been recorded during twenty-one years, and the male births were to the female births as 99.7 to 100. In greyhounds the inequality is greater than with any other animal, for out of 6878 births during twelve years, the male births were to the female as 110.1 to 100. It is, however, in some degree doubtful whether it is safe to infer that the proportion would be the same under natural conditions as under domestication; for slight and unknown differences in the conditions affect the proportion of the sexes. Thus with mankind, the male births in England are as 104.5, in Russia as 108.9, and with the Jews of Livonia as 120, to 100 female births. But I shall recur to this curious point of the excess of male births in the supplement to this chapter. At the Cape of Good Hope, however, male children of European extraction have been born during several years in the proportion of between 90 and 99 to 100 female children. For our present purpose we are concerned with the proportions of the sexes, not only at birth, but also at maturity, and this adds another element of doubt; for it is a well-ascertained fact that with man the number of males dying before or during birth, and during the first two years of infancy, is considerably larger than that of females. So it almost certainly is with male lambs, and probably with some other animals. The males of some species kill one another by fighting; or they drive one another about until they become greatly emaciated. They must also be often exposed to various dangers, whilst wandering about in eager search for the females. In many kinds of fish the males are much smaller than the females, and they are believed often to be devoured by the latter, or by other fishes. The females of some birds appear to die earlier than the males; they are also liable to be destroyed on their nests, or whilst in charge of their young. With insects the female larvae are often larger than those of the males, and would consequently be more likely to be devoured. In some cases the mature females are less active and less rapid in their movements than the males, and could not escape so well from danger. Hence, with animals in a state of nature, we must rely on mere estimation, in order to judge of the proportions of the sexes at maturity; and this is but little trustworthy, except when the inequality is strongly marked. Nevertheless, as far as a judgment can be formed, we may conclude from the facts given in the supplement, that the males of some few mammals, of many birds, of some fish and insects, are considerably more numerous than the females. The proportion between the sexes fluctuates slightly during successive years: thus with race-horses, for every 100 mares born the stallions varied from 107.1 in one year to 92.6 in another year, and with greyhounds from 116.3 to 95.3. But had larger numbers been tabulated throughout an area more extensive than England, these fluctuations would probably have disappeared; and such as they are, would hardly suffice to lead to effective sexual selection in a state of nature. Nevertheless, in the cases of some few wild animals, as shewn in the supplement, the proportions seem to fluctuate either during different seasons or in different localities in a sufficient degree to lead to such selection. For it should be observed that any advantage, gained during certain years or in certain localities by those males which were able to conquer their rivals, or were the most attractive to the females, would probably be transmitted to the offspring, and would not subsequently be eliminated. During the succeeding seasons, when, from the equality of the sexes, every male was able to procure a female, the stronger or more attractive males previously produced would still have at least as good a chance of leaving offspring as the weaker or less attractive. POLYGAMY. The practice of polygamy leads to the same results as would follow from an actual inequality in the number of the sexes; for if each male secures two or more females, many males cannot pair; and the latter assuredly will be the weaker or less attractive individuals. Many mammals and some few birds are polygamous, but with animals belonging to the lower classes I have found no evidence of this habit. The intellectual powers of such animals are, perhaps, not sufficient to lead them to collect and guard a harem of females. That some relation exists between polygamy and the development of secondary sexual characters, appears nearly certain; and this supports the view that a numerical preponderance of males would be eminently favourable to the action of sexual selection. Nevertheless many animals, which are strictly monogamous, especially birds, display strongly-marked secondary sexual characters; whilst some few animals, which are polygamous, do not have such characters. We will first briefly run through the mammals, and then turn to birds. The gorilla seems to be polygamous, and the male differs considerably from the female; so it is with some baboons, which live in herds containing twice as many adult females as males. In South America the Mycetes caraya presents well-marked sexual differences, in colour, beard, and vocal organs; and the male generally lives with two or three wives: the male of the Cebus capucinus differs somewhat from the female, and appears to be polygamous. (10. On the Gorilla, Savage and Wyman, 'Boston Journal of Natural History,' vol. v. 1845-47, p. 423. On Cynocephalus, Brehm, 'Thierleben,' B. i. 1864, s. 77. On Mycetes, Rengger, 'Naturgeschichte der Säugethiere von Paraguay,' 1830, ss. 14, 20. On Cebus, Brehm, ibid. s. 108.) Little is known on this head with respect to most other monkeys, but some species are strictly monogamous. The ruminants are eminently polygamous, and they present sexual differences more frequently than almost any other group of mammals; this holds good, especially in their weapons, but also in other characters. Most deer, cattle, and sheep are polygamous; as are most antelopes, though some are monogamous. Sir Andrew Smith, in speaking of the antelopes of South Africa, says that in herds of about a dozen there was rarely more than one mature male. The Asiatic Antilope saiga appears to be the most inordinate polygamist in the world; for Pallas (11. Pallas, 'Spicilegia Zoolog., Fasc.' xii. 1777, p. 29. Sir Andrew Smith, 'Illustrations of the Zoology of S. Africa,' 1849, pl. 29, on the Kobus. Owen, in his 'Anatomy of Vertebrates' (vol. iii. 1868, p. 633) gives a table shewing incidentally which species of antelopes are gregarious.) states that the male drives away all rivals, and collects a herd of about a hundred females and kids together; the female is hornless and has softer hair, but does not otherwise differ much from the male. The wild horse of the Falkland Islands and of the Western States of N. America is polygamous, but, except in his greater size and in the proportions of his body, differs but little from the mare. The wild boar presents well-marked sexual characters, in his great tusks and some other points. In Europe and in India he leads a solitary life, except during the breeding-season; but as is believed by Sir W. Elliot, who has had many opportunities in India of observing this animal, he consorts at this season with several females. Whether this holds good in Europe is doubtful, but it is supported by some evidence. The adult male Indian elephant, like the boar, passes much of his time in solitude; but as Dr. Campbell states, when with others, "It is rare to find more than one male with a whole herd of females"; the larger males expelling or killing the smaller and weaker ones. The male differs from the female in his immense tusks, greater size, strength, and endurance; so great is the difference in these respects that the males when caught are valued at one-fifth more than the females. (12. Dr. Campbell, in 'Proc. Zoolog. Soc.' 1869, p. 138. See also an interesting paper by Lieut. Johnstone, in 'Proceedings, Asiatic Society of Bengal,' May 1868.) The sexes of other pachydermatous animals differ very little or not at all, and, as far as known, they are not polygamists. Nor have I heard of any species in the Orders of Cheiroptera, Edentata, Insectivora and Rodents being polygamous, excepting that amongst the Rodents, the common rat, according to some rat-catchers, lives with several females. Nevertheless the two sexes of some sloths (Edentata) differ in the character and colour of certain patches of hair on their shoulders. (13. Dr. Gray, in 'Annals and Magazine of Natural History,' 1871, p. 302.) And many kinds of bats (Cheiroptera) present well-marked sexual differences, chiefly in the males possessing odoriferous glands and pouches, and by their being of a lighter colour. (14. See Dr. Dobson's excellent paper in 'Proceedings of the Zoological Society,' 1873, p. 241.) In the great order of Rodents, as far as I can learn, the sexes rarely differ, and when they do so, it is but slightly in the tint of the fur. As I hear from Sir Andrew Smith, the lion in South Africa sometimes lives with a single female, but generally with more, and, in one case, was found with as many as five females; so that he is polygamous. As far as I can discover, he is the only polygamist amongst all the terrestrial Carnivora, and he alone presents well-marked sexual characters. If, however, we turn to the marine Carnivora, as we shall hereafter see, the case is widely different; for many species of seals offer extraordinary sexual differences, and they are eminently polygamous. Thus, according to Peron, the male sea-elephant of the Southern Ocean always possesses several females, and the sea-lion of Forster is said to be surrounded by from twenty to thirty females. In the North, the male sea-bear of Steller is accompanied by even a greater number of females. It is an interesting fact, as Dr. Gill remarks (15. 'The Eared Seals,' American Naturalist, vol. iv. Jan. 1871.), that in the monogamous species, "or those living in small communities, there is little difference in size between the males and females; in the social species, or rather those of which the males have harems, the males are vastly larger than the females." Amongst birds, many species, the sexes of which differ greatly from each other, are certainly monogamous. In Great Britain we see well-marked sexual differences, for instance, in the wild-duck which pairs with a single female, the common blackbird, and the bullfinch which is said to pair for life. I am informed by Mr. Wallace that the like is true of the Chatterers or Cotingidae of South America, and of many other birds. In several groups I have not been able to discover whether the species are polygamous or monogamous. Lesson says that birds of paradise, so remarkable for their sexual differences, are polygamous, but Mr. Wallace doubts whether he had sufficient evidence. Mr. Salvin tells me he has been led to believe that humming-birds are polygamous. The male widow-bird, remarkable for his caudal plumes, certainly seems to be a polygamist. (16. 'The Ibis,' vol. iii. 1861, p. 133, on the Progne Widow-bird. See also on the Vidua axillaris, ibid. vol. ii. 1860, p. 211. On the polygamy of the Capercailzie and Great Bustard, see L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 19, and 182. Montagu and Selby speak of the Black Grouse as polygamous and of the Red Grouse as monogamous.) I have been assured by Mr. Jenner Weir and by others, that it is somewhat common for three starlings to frequent the same nest; but whether this is a case of polygamy or polyandry has not been ascertained. The Gallinaceae exhibit almost as strongly marked sexual differences as birds of paradise or humming-birds, and many of the species are, as is well known, polygamous; others being strictly monogamous. What a contrast is presented between the sexes of the polygamous peacock or pheasant, and the monogamous guinea-fowl or partridge! Many similar cases could be given, as in the grouse tribe, in which the males of the polygamous capercailzie and black-cock differ greatly from the females; whilst the sexes of the monogamous red grouse and ptarmigan differ very little. In the Cursores, except amongst the bustards, few species offer strongly-marked sexual differences, and the great bustard (Otis tarda) is said to be polygamous. With the Grallatores, extremely few species differ sexually, but the ruff (Machetes pugnax) affords a marked exception, and this species is believed by Montagu to be a polygamist. Hence it appears that amongst birds there often exists a close relation between polygamy and the development of strongly-marked sexual differences. I asked Mr. Bartlett, of the Zoological Gardens, who has had very large experience with birds, whether the male tragopan (one of the Gallinaceae) was polygamous, and I was struck by his answering, "I do not know, but should think so from his splendid colours." It deserves notice that the instinct of pairing with a single female is easily lost under domestication. The wild-duck is strictly monogamous, the domestic-duck highly polygamous. The Rev. W.D. Fox informs me that out of some half-tamed wild-ducks, on a large pond in his neighbourhood, so many mallards were shot by the gamekeeper that only one was left for every seven or eight females; yet unusually large broods were reared. The guinea-fowl is strictly monogamous; but Mr. Fox finds that his birds succeed best when he keeps one cock to two or three hens. Canary-birds pair in a state of nature, but the breeders in England successfully put one male to four or five females. I have noticed these cases, as rendering it probable that wild monogamous species might readily become either temporarily or permanently polygamous. Too little is known of the habits of reptiles and fishes to enable us to speak of their marriage arrangements. The stickle-back (Gasterosteus), however, is said to be a polygamist (17. Noel Humphreys, 'River Gardens,' 1857.); and the male during the breeding-season differs conspicuously from the female. To sum up on the means through which, as far as we can judge, sexual selection has led to the development of secondary sexual characters. It has been shewn that the largest number of vigorous offspring will be reared from the pairing of the strongest and best-armed males, victorious in contests over other males, with the most vigorous and best-nourished females, which are the first to breed in the spring. If such females select the more attractive, and at the same time vigorous males, they will rear a larger number of offspring than the retarded females, which must pair with the less vigorous and less attractive males. So it will be if the more vigorous males select the more attractive and at the same time healthy and vigorous females; and this will especially hold good if the male defends the female, and aids in providing food for the young. The advantage thus gained by the more vigorous pairs in rearing a larger number of offspring has apparently sufficed to render sexual selection efficient. But a large numerical preponderance of males over females will be still more efficient; whether the preponderance is only occasional and local, or permanent; whether it occurs at birth, or afterwards from the greater destruction of the females; or whether it indirectly follows from the practice of polygamy. THE MALE GENERALLY MORE MODIFIED THAN THE FEMALE. Throughout the animal kingdom, when the sexes differ in external appearance, it is, with rare exceptions, the male which has been the more modified; for, generally, the female retains a closer resemblance to the young of her own species, and to other adult members of the same group. The cause of this seems to lie in the males of almost all animals having stronger passions than the females. Hence it is the males that fight together and sedulously display their charms before the females; and the victors transmit their superiority to their male offspring. Why both sexes do not thus acquire the characters of their fathers, will be considered hereafter. That the males of all mammals eagerly pursue the females is notorious to every one. So it is with birds; but many cock birds do not so much pursue the hen, as display their plumage, perform strange antics, and pour forth their song in her presence. The male in the few fish observed seems much more eager than the female; and the same is true of alligators, and apparently of Batrachians. Throughout the enormous class of insects, as Kirby remarks, "the law is that the male shall seek the female." (18. Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 342.) Two good authorities, Mr. Blackwall and Mr. C. Spence Bate, tell me that the males of spiders and crustaceans are more active and more erratic in their habits than the females. When the organs of sense or locomotion are present in the one sex of insects and crustaceans and absent in the other, or when, as is frequently the case, they are more highly developed in the one than in the other, it is, as far as I can discover, almost invariably the male which retains such organs, or has them most developed; and this shews that the male is the more active member in the courtship of the sexes. (19. One parasitic Hymenopterous insect (Westwood, 'Modern Class. of Insects,' vol. ii. p. 160) forms an exception to the rule, as the male has rudimentary wings, and never quits the cell in which it is born, whilst the female has well-developed wings. Audouin believes that the females of this species are impregnated by the males which are born in the same cells with them; but it is much more probable that the females visit other cells, so that close inter-breeding is thus avoided. We shall hereafter meet in various classes, with a few exceptional cases, in which the female, instead of the male, is the seeker and wooer.) The female, on the other hand, with the rarest exceptions, is less eager than the male. As the illustrious Hunter (20. 'Essays and Observations,' edited by Owen, vol. i. 1861, p. 194.) long ago observed, she generally "requires to be courted;" she is coy, and may often be seen endeavouring for a long time to escape from the male. Every observer of the habits of animals will be able to call to mind instances of this kind. It is shewn by various facts, given hereafter, and by the results fairly attributable to sexual selection, that the female, though comparatively passive, generally exerts some choice and accepts one male in preference to others. Or she may accept, as appearances would sometimes lead us to believe, not the male which is the most attractive to her, but the one which is the least distasteful. The exertion of some choice on the part of the female seems a law almost as general as the eagerness of the male. We are naturally led to enquire why the male, in so many and such distinct classes, has become more eager than the female, so that he searches for her, and plays the more active part in courtship. It would be no advantage and some loss of power if each sex searched for the other; but why should the male almost always be the seeker? The ovules of plants after fertilisation have to be nourished for a time; hence the pollen is necessarily brought to the female organs--being placed on the stigma, by means of insects or the wind, or by the spontaneous movements of the stamens; and in the Algae, etc., by the locomotive power of the antherozooids. With lowly-organised aquatic animals, permanently affixed to the same spot and having their sexes separate, the male element is invariably brought to the female; and of this we can see the reason, for even if the ova were detached before fertilisation, and did not require subsequent nourishment or protection, there would yet be greater difficulty in transporting them than the male element, because, being larger than the latter, they are produced in far smaller numbers. So that many of the lower animals are, in this respect, analogous with plants. (21. Prof. Sachs ('Lehrbuch der Botanik,' 1870, S. 633) in speaking of the male and female reproductive cells, remarks, "verhält sich die eine bei der Vereinigung activ,...die andere erscheint bei der Vereinigung passiv.") The males of affixed and aquatic animals having been led to emit their fertilising element in this way, it is natural that any of their descendants, which rose in the scale and became locomotive, should retain the same habit; and they would approach the female as closely as possible, in order not to risk the loss of the fertilising element in a long passage of it through the water. With some few of the lower animals, the females alone are fixed, and the males of these must be the seekers. But it is difficult to understand why the males of species, of which the progenitors were primordially free, should invariably have acquired the habit of approaching the females, instead of being approached by them. But in all cases, in order that the males should seek efficiently, it would be necessary that they should be endowed with strong passions; and the acquirement of such passions would naturally follow from the more eager leaving a larger number of offspring than the less eager. The great eagerness of the males has thus indirectly led to their much more frequently developing secondary sexual characters than the females. But the development of such characters would be much aided, if the males were more liable to vary than the females--as I concluded they were--after a long study of domesticated animals. Von Nathusius, who has had very wide experience, is strongly of the same opinion. (22. 'Vorträge uber Viehzucht,' 1872, p. 63.) Good evidence also in favour of this conclusion can be produced by a comparison of the two sexes in mankind. During the Novara Expedition (23. 'Reise der Novara: Anthropolog. Theil,' 1867, ss. 216-269. The results were calculated by Dr. Weisbach from measurements made by Drs. K. Scherzer and Schwarz. On the greater variability of the males of domesticated animals, see my 'Variation of Animals and Plants under Domestication,' vol. ii. 1868, p. 75.) a vast number of measurements was made of various parts of the body in different races, and the men were found in almost every case to present a greater range of variation than the women; but I shall have to recur to this subject in a future chapter. Mr. J. Wood (24. 'Proceedings of the Royal Society,' vol. xvi. July 1868, pp. 519 and 524.), who has carefully attended to the variation of the muscles in man, puts in italics the conclusion that "the greatest number of abnormalities in each subject is found in the males." He had previously remarked that "altogether in 102 subjects, the varieties of redundancy were found to be half as many again as in females, contrasting widely with the greater frequency of deficiency in females before described." Professor Macalister likewise remarks (25. 'Proc. Royal Irish Academy,' vol. x. 1868, p. 123.) that variations in the muscles "are probably more common in males than females." Certain muscles which are not normally present in mankind are also more frequently developed in the male than in the female sex, although exceptions to this rule are said to occur. Dr. Burt Wilder (26. 'Massachusetts Medical Society,' vol. ii. No. 3, 1868, p. 9.) has tabulated the cases of 152 individuals with supernumerary digits, of which 86 were males, and 39, or less than half, females, the remaining 27 being of unknown sex. It should not, however, be overlooked that women would more frequently endeavour to conceal a deformity of this kind than men. Again, Dr. L. Meyer asserts that the ears of man are more variable in form than those of a woman. (27. 'Archiv fur Path. Anat. und Phys.' 1871, p. 488.) Lastly the temperature is more variable in man than in woman. (28. The conclusions recently arrived at by Dr. J. Stockton Hough, on the temperature of man, are given in the 'Pop. Sci. Review,' Jan. 1st, 1874, p. 97.) The cause of the greater general variability in the male sex, than in the female is unknown, except in so far as secondary sexual characters are extraordinarily variable, and are usually confined to the males; and, as we shall presently see, this fact is, to a certain extent, intelligible. Through the action of sexual and natural selection male animals have been rendered in very many instances widely different from their females; but independently of selection the two sexes, from differing constitutionally, tend to vary in a somewhat different manner. The female has to expend much organic matter in the formation of her ova, whereas the male expends much force in fierce contests with his rivals, in wandering about in search of the female, in exerting his voice, pouring out odoriferous secretions, etc.: and this expenditure is generally concentrated within a short period. The great vigour of the male during the season of love seems often to intensify his colours, independently of any marked difference from the female. (29. Prof. Mantegazza is inclined to believe ('Lettera a Carlo Darwin,' 'Archivio per l'Anthropologia,' 1871, p. 306) that the bright colours, common in so many male animals, are due to the presence and retention by them of the spermatic fluid; but this can hardly be the case; for many male birds, for instance young pheasants, become brightly coloured in the autumn of their first year.) In mankind, and even as low down in the organic scale as in the Lepidoptera, the temperature of the body is higher in the male than in the female, accompanied in the case of man by a slower pulse. (30. For mankind, see Dr. J. Stockton Hough, whose conclusions are given in the 'Popular Science Review,' 1874, p. 97. See Girard's observations on the Lepidoptera, as given in the 'Zoological Record,' 1869, p. 347.) On the whole the expenditure of matter and force by the two sexes is probably nearly equal, though effected in very different ways and at different rates. From the causes just specified the two sexes can hardly fail to differ somewhat in constitution, at least during the breeding-season; and, although they may be subjected to exactly the same conditions, they will tend to vary in a different manner. If such variations are of no service to either sex, they will not be accumulated and increased by sexual or natural selection. Nevertheless, they may become permanent if the exciting cause acts permanently; and in accordance with a frequent form of inheritance they may be transmitted to that sex alone in which they first appeared. In this case the two sexes will come to present permanent, yet unimportant, differences of character. For instance, Mr. Allen shews that with a large number of birds inhabiting the northern and southern United States, the specimens from the south are darker-coloured than those from the north; and this seems to be the direct result of the difference in temperature, light, etc., between the two regions. Now, in some few cases, the two sexes of the same species appear to have been differently affected; in the Agelaeus phoeniceus the males have had their colours greatly intensified in the south; whereas with Cardinalis virginianus it is the females which have been thus affected; with Quiscalus major the females have been rendered extremely variable in tint, whilst the males remain nearly uniform. (31. 'Mammals and Birds of E. Florida,' pp. 234, 280, 295.) A few exceptional cases occur in various classes of animals, in which the females instead of the males have acquired well pronounced secondary sexual characters, such as brighter colours, greater size, strength, or pugnacity. With birds there has sometimes been a complete transposition of the ordinary characters proper to each sex; the females having become the more eager in courtship, the males remaining comparatively passive, but apparently selecting the more attractive females, as we may infer from the results. Certain hen birds have thus been rendered more highly coloured or otherwise ornamented, as well as more powerful and pugnacious than the cocks; these characters being transmitted to the female offspring alone. It may be suggested that in some cases a double process of selection has been carried on; that the males have selected the more attractive females, and the latter the more attractive males. This process, however, though it might lead to the modification of both sexes, would not make the one sex different from the other, unless indeed their tastes for the beautiful differed; but this is a supposition too improbable to be worth considering in the case of any animal, excepting man. There are, however, many animals in which the sexes resemble each other, both being furnished with the same ornaments, which analogy would lead us to attribute to the agency of sexual selection. In such cases it may be suggested with more plausibility, that there has been a double or mutual process of sexual selection; the more vigorous and precocious females selecting the more attractive and vigorous males, the latter rejecting all except the more attractive females. But from what we know of the habits of animals, this view is hardly probable, for the male is generally eager to pair with any female. It is more probable that the ornaments common to both sexes were acquired by one sex, generally the male, and then transmitted to the offspring of both sexes. If, indeed, during a lengthened period the males of any species were greatly to exceed the females in number, and then during another lengthened period, but under different conditions, the reverse were to occur, a double, but not simultaneous, process of sexual selection might easily be carried on, by which the two sexes might be rendered widely different. We shall hereafter see that many animals exist, of which neither sex is brilliantly coloured or provided with special ornaments, and yet the members of both sexes or of one alone have probably acquired simple colours, such as white or black, through sexual selection. The absence of bright tints or other ornaments may be the result of variations of the right kind never having occurred, or of the animals themselves having preferred plain black or white. Obscure tints have often been developed through natural selection for the sake of protection, and the acquirement through sexual selection of conspicuous colours, appears to have been sometimes checked from the danger thus incurred. But in other cases the males during long ages may have struggled together for the possession of the females, and yet no effect will have been produced, unless a larger number of offspring were left by the more successful males to inherit their superiority, than by the less successful: and this, as previously shewn, depends on many complex contingencies. Sexual selection acts in a less rigorous manner than natural selection. The latter produces its effects by the life or death at all ages of the more or less successful individuals. Death, indeed, not rarely ensues from the conflicts of rival males. But generally the less successful male merely fails to obtain a female, or obtains a retarded and less vigorous female later in the season, or, if polygamous, obtains fewer females; so that they leave fewer, less vigorous, or no offspring. In regard to structures acquired through ordinary or natural selection, there is in most cases, as long as the conditions of life remain the same, a limit to the amount of advantageous modification in relation to certain special purposes; but in regard to structures adapted to make one male victorious over another, either in fighting or in charming the female, there is no definite limit to the amount of advantageous modification; so that as long as the proper variations arise the work of sexual selection will go on. This circumstance may partly account for the frequent and extraordinary amount of variability presented by secondary sexual characters. Nevertheless, natural selection will determine that such characters shall not be acquired by the victorious males, if they would be highly injurious, either by expending too much of their vital powers, or by exposing them to any great danger. The development, however, of certain structures--of the horns, for instance, in certain stags--has been carried to a wonderful extreme; and in some cases to an extreme which, as far as the general conditions of life are concerned, must be slightly injurious to the male. From this fact we learn that the advantages which favoured males derive from conquering other males in battle or courtship, and thus leaving a numerous progeny, are in the long run greater than those derived from rather more perfect adaptation to their conditions of life. We shall further see, and it could never have been anticipated, that the power to charm the female has sometimes been more important than the power to conquer other males in battle. LAWS OF INHERITANCE. In order to understand how sexual selection has acted on many animals of many classes, and in the course of ages has produced a conspicuous result, it is necessary to bear in mind the laws of inheritance, as far as they are known. Two distinct elements are included under the term "inheritance"--the transmission, and the development of characters; but as these generally go together, the distinction is often overlooked. We see this distinction in those characters which are transmitted through the early years of life, but are developed only at maturity or during old age. We see the same distinction more clearly with secondary sexual characters, for these are transmitted through both sexes, though developed in one alone. That they are present in both sexes, is manifest when two species, having strongly-marked sexual characters, are crossed, for each transmits the characters proper to its own male and female sex to the hybrid offspring of either sex. The same fact is likewise manifest, when characters proper to the male are occasionally developed in the female when she grows old or becomes diseased, as, for instance, when the common hen assumes the flowing tail-feathers, hackles, comb, spurs, voice, and even pugnacity of the cock. Conversely, the same thing is evident, more or less plainly, with castrated males. Again, independently of old age or disease, characters are occasionally transferred from the male to the female, as when, in certain breeds of the fowl, spurs regularly appear in the young and healthy females. But in truth they are simply developed in the female; for in every breed each detail in the structure of the spur is transmitted through the female to her male offspring. Many cases will hereafter be given, where the female exhibits, more or less perfectly, characters proper to the male, in whom they must have been first developed, and then transferred to the female. The converse case of the first development of characters in the female and of transference to the male, is less frequent; it will therefore be well to give one striking instance. With bees the pollen-collecting apparatus is used by the female alone for gathering pollen for the larvae, yet in most of the species it is partially developed in the males to whom it is quite useless, and it is perfectly developed in the males of Bombus or the humble-bee. (32. H. Muller, 'Anwendung der Darwin'schen Lehre,' etc., Verh. d. n. V. Jahrg., xxix. p. 42.) As not a single other Hymenopterous insect, not even the wasp, which is closely allied to the bee, is provided with a pollen-collecting apparatus, we have no grounds for supposing that male bees primordially collected pollen as well as the females; although we have some reason to suspect that male mammals primordially suckled their young as well as the females. Lastly, in all cases of reversion, characters are transmitted through two, three, or many more generations, and are then developed under certain unknown favourable conditions. This important distinction between transmission and development will be best kept in mind by the aid of the hypothesis of pangenesis. According to this hypothesis, every unit or cell of the body throws off gemmules or undeveloped atoms, which are transmitted to the offspring of both sexes, and are multiplied by self-division. They may remain undeveloped during the early years of life or during successive generations; and their development into units or cells, like those from which they were derived, depends on their affinity for, and union with other units or cells previously developed in the due order of growth. INHERITANCE AT CORRESPONDING PERIODS OF LIFE. This tendency is well established. A new character, appearing in a young animal, whether it lasts throughout life or is only transient, will, in general, reappear in the offspring at the same age and last for the same time. If, on the other hand, a new character appears at maturity, or even during old age, it tends to reappear in the offspring at the same advanced age. When deviations from this rule occur, the transmitted characters much oftener appear before, than after the corresponding age. As I have dwelt on this subject sufficiently in another work (33. The 'Variation of Animals and Plants under Domestication,' vol. ii. 1868, p. 75. In the last chapter but one, the provisional hypothesis of pangenesis, above alluded to, is fully explained.), I will here merely give two or three instances, for the sake of recalling the subject to the reader's mind. In several breeds of the Fowl, the down-covered chickens, the young birds in their first true plumage, and the adults differ greatly from one another, as well as from their common parent-form, the Gallus bankiva; and these characters are faithfully transmitted by each breed to their offspring at the corresponding periods of life. For instance, the chickens of spangled Hamburgs, whilst covered with down, have a few dark spots on the head and rump, but are not striped longitudinally, as in many other breeds; in their first true plumage, "they are beautifully pencilled," that is each feather is transversely marked by numerous dark bars; but in their second plumage the feathers all become spangled or tipped with a dark round spot. (34. These facts are given on the high authority of a great breeder, Mr. Teebay; see Tegetmeier's 'Poultry Book,' 1868, p. 158. On the characters of chickens of different breeds, and on the breeds of the pigeon, alluded to in the following paragraph, see 'Variation of Animals,' etc., vol. i. pp. 160, 249; vol. ii. p. 77.) Hence in this breed variations have occurred at, and been transmitted to, three distinct periods of life. The Pigeon offers a more remarkable case, because the aboriginal parent species does not undergo any change of plumage with advancing age, excepting that at maturity the breast becomes more iridescent; yet there are breeds which do not acquire their characteristic colours until they have moulted two, three, or four times; and these modifications of plumage are regularly transmitted. INHERITANCE AT CORRESPONDING SEASONS OF THE YEAR. With animals in a state of nature, innumerable instances occur of characters appearing periodically at different seasons. We see this in the horns of the stag, and in the fur of Arctic animals which becomes thick and white during the winter. Many birds acquire bright colours and other decorations during the breeding-season alone. Pallas states (35. 'Novae species Quadrupedum e Glirium ordine,' 1778, p. 7. On the transmission of colour by the horse, see 'Variation of Animals and Plants under Domestication,' vol. i. p. 51. Also vol. ii. p. 71, for a general discussion on 'Inheritance as limited by Sex.'), that in Siberia domestic cattle and horses become lighter-coloured during the winter; and I have myself observed, and heard of similar strongly marked changes of colour, that is, from brownish cream-colour or reddish-brown to a perfect white, in several ponies in England. Although I do not know that this tendency to change the colour of the coat during different seasons is transmitted, yet it probably is so, as all shades of colour are strongly inherited by the horse. Nor is this form of inheritance, as limited by the seasons, more remarkable than its limitation by age or sex. INHERITANCE AS LIMITED BY SEX. The equal transmission of characters to both sexes is the commonest form of inheritance, at least with those animals which do not present strongly-marked sexual differences, and indeed with many of these. But characters are somewhat commonly transferred exclusively to that sex, in which they first appear. Ample evidence on this head has been advanced in my work on 'Variation under Domestication,' but a few instances may here be given. There are breeds of the sheep and goat, in which the horns of the male differ greatly in shape from those of the female; and these differences, acquired under domestication, are regularly transmitted to the same sex. As a rule, it is the females alone in cats which are tortoise-shell, the corresponding colour in the males being rusty-red. With most breeds of the fowl, the characters proper to each sex are transmitted to the same sex alone. So general is this form of transmission that it is an anomaly when variations in certain breeds are transmitted equally to both sexes. There are also certain sub-breeds of the fowl in which the males can hardly be distinguished from one another, whilst the females differ considerably in colour. The sexes of the pigeon in the parent-species do not differ in any external character; nevertheless, in certain domesticated breeds the male is coloured differently from the female. (36. Dr. Chapuis, 'Le Pigeon Voyageur Belge,' 1865, p. 87. Boitard et Corbie, 'Les Pigeons de Volière,' etc., 1824, p. 173. See, also, on similar differences in certain breeds at Modena, 'Le variazioni dei Colombi domestici,' del Paolo Bonizzi, 1873.) The wattle in the English Carrier pigeon, and the crop in the Pouter, are more highly developed in the male than in the female; and although these characters have been gained through long-continued selection by man, the slight differences between the sexes are wholly due to the form of inheritance which has prevailed; for they have arisen, not from, but rather in opposition to, the wish of the breeder. Most of our domestic races have been formed by the accumulation of many slight variations; and as some of the successive steps have been transmitted to one sex alone, and some to both sexes, we find in the different breeds of the same species all gradations between great sexual dissimilarity and complete similarity. Instances have already been given with the breeds of the fowl and pigeon, and under nature analogous cases are common. With animals under domestication, but whether in nature I will not venture to say, one sex may lose characters proper to it, and may thus come somewhat to resemble the opposite sex; for instance, the males of some breeds of the fowl have lost their masculine tail-plumes and hackles. On the other hand, the differences between the sexes may be increased under domestication, as with merino sheep, in which the ewes have lost their horns. Again, characters proper to one sex may suddenly appear in the other sex; as in those sub-breeds of the fowl in which the hens acquire spurs whilst young; or, as in certain Polish sub-breeds, in which the females, as there is reason to believe, originally acquired a crest, and subsequently transferred it to the males. All these cases are intelligible on the hypothesis of pangenesis; for they depend on the gemmules of certain parts, although present in both sexes, becoming, through the influence of domestication, either dormant or developed in either sex. There is one difficult question which it will be convenient to defer to a future chapter; namely, whether a character at first developed in both sexes, could through selection be limited in its development to one sex alone. If, for instance, a breeder observed that some of his pigeons (of which the characters are usually transferred in an equal degree to both sexes) varied into pale blue, could he by long-continued selection make a breed, in which the males alone should be of this tint, whilst the females remained unchanged? I will here only say, that this, though perhaps not impossible, would be extremely difficult; for the natural result of breeding from the pale-blue males would be to change the whole stock of both sexes to this tint. If, however, variations of the desired tint appeared, which were from the first limited in their development to the male sex, there would not be the least difficulty in making a breed with the two sexes of a different colour, as indeed has been effected with a Belgian breed, in which the males alone are streaked with black. In a similar manner, if any variation appeared in a female pigeon, which was from the first sexually limited in its development to the females, it would be easy to make a breed with the females alone thus characterised; but if the variation was not thus originally limited, the process would be extremely difficult, perhaps impossible. (37. Since the publication of the first edition of this work, it has been highly satisfactory to me to find the following remarks (the 'Field,' Sept. 1872) from so experienced a breeder as Mr. Tegetmeier. After describing some curious cases in pigeons, of the transmission of colour by one sex alone, and the formation of a sub-breed with this character, he says: "It is a singular circumstance that Mr. Darwin should have suggested the possibility of modifying the sexual colours of birds by a course of artificial selection. When he did so, he was in ignorance of these facts that I have related; but it is remarkable how very closely he suggested the right method of procedure.") ON THE RELATION BETWEEN THE PERIOD OF DEVELOPMENT OF A CHARACTER AND ITS TRANSMISSION TO ONE SEX OR TO BOTH SEXES. Why certain characters should be inherited by both sexes, and other characters by one sex alone, namely by that sex in which the character first appeared, is in most cases quite unknown. We cannot even conjecture why with certain sub-breeds of the pigeon, black striae, though transmitted through the female, should be developed in the male alone, whilst every other character is equally transferred to both sexes. Why, again, with cats, the tortoise-shell colour should, with rare exceptions, be developed in the female alone. The very same character, such as deficient or supernumerary digits, colour-blindness, etc., may with mankind be inherited by the males alone of one family, and in another family by the females alone, though in both cases transmitted through the opposite as well as through the same sex. (38. References are given in my 'Variation of Animals and Plants under Domestication,' vol. ii. p. 72.) Although we are thus ignorant, the two following rules seem often to hold good--that variations which first appear in either sex at a late period of life, tend to be developed in the same sex alone; whilst variations which first appear early in life in either sex tend to be developed in both sexes. I am, however, far from supposing that this is the sole determining cause. As I have not elsewhere discussed this subject, and it has an important bearing on sexual selection, I must here enter into lengthy and somewhat intricate details. It is in itself probable that any character appearing at an early age would tend to be inherited equally by both sexes, for the sexes do not differ much in constitution before the power of reproduction is gained. On the other hand, after this power has been gained and the sexes have come to differ in constitution, the gemmules (if I may again use the language of pangenesis) which are cast off from each varying part in the one sex would be much more likely to possess the proper affinities for uniting with the tissues of the same sex, and thus becoming developed, than with those of the opposite sex. I was first led to infer that a relation of this kind exists, from the fact that whenever and in whatever manner the adult male differs from the adult female, he differs in the same manner from the young of both sexes. The generality of this fact is quite remarkable: it holds good with almost all mammals, birds, amphibians, and fishes; also with many crustaceans, spiders, and some few insects, such as certain orthoptera and libellulae. In all these cases the variations, through the accumulation of which the male acquired his proper masculine characters, must have occurred at a somewhat late period of life; otherwise the young males would have been similarly characterised; and conformably with our rule, the variations are transmitted to and developed in the adult males alone. When, on the other hand, the adult male closely resembles the young of both sexes (these, with rare exceptions, being alike), he generally resembles the adult female; and in most of these cases the variations through which the young and old acquired their present characters, probably occurred, according to our rule, during youth. But there is here room for doubt, for characters are sometimes transferred to the offspring at an earlier age than that at which they first appeared in the parents, so that the parents may have varied when adult, and have transferred their characters to their offspring whilst young. There are, moreover, many animals, in which the two sexes closely resemble each other, and yet both differ from their young: and here the characters of the adults must have been acquired late in life; nevertheless, these characters, in apparent contradiction to our rule, are transferred to both sexes. We must not however, overlook the possibility or even probability of successive variations of the same nature occurring, under exposure to similar conditions, simultaneously in both sexes at a rather late period of life; and in this case the variations would be transferred to the offspring of both sexes at a corresponding late age; and there would then be no real contradiction to the rule that variations occurring late in life are transferred exclusively to the sex in which they first appeared. This latter rule seems to hold true more generally than the second one, namely, that variations which occur in either sex early in life tend to be transferred to both sexes. As it was obviously impossible even to estimate in how large a number of cases throughout the animal kingdom these two propositions held good, it occurred to me to investigate some striking or crucial instances, and to rely on the result. An excellent case for investigation is afforded by the Deer family. In all the species, but one, the horns are developed only in the males, though certainly transmitted through the females, and capable of abnormal development in them. In the reindeer, on the other hand, the female is provided with horns; so that in this species, the horns ought, according to our rule, to appear early in life, long before the two sexes are mature and have come to differ much in constitution. In all the other species the horns ought to appear later in life, which would lead to their development in that sex alone, in which they first appeared in the progenitor of the whole Family. Now in seven species, belonging to distinct sections of the family and inhabiting different regions, in which the stags alone bear horns, I find that the horns first appear at periods, varying from nine months after birth in the roebuck, to ten, twelve or even more months in the stags of the six other and larger species. (39. I am much obliged to Mr. Cupples for having made enquiries for me in regard to the Roebuck and Red Deer of Scotland from Mr. Robertson, the experienced head-forester to the Marquis of Breadalbane. In regard to Fallow-deer, I have to thank Mr. Eyton and others for information. For the Cervus alces of N. America, see 'Land and Water,' 1868, pp. 221 and 254; and for the C. Virginianus and strongyloceros of the same continent, see J.D. Caton, in 'Ottawa Acad. of Nat. Sc.' 1868, p. 13. For Cervus Eldi of Pegu, see Lieut. Beaven, 'Proccedings of the Zoological Society,' 1867, p. 762.) But with the reindeer the case is widely different; for, as I hear from Prof. Nilsson, who kindly made special enquiries for me in Lapland, the horns appear in the young animals within four or five weeks after birth, and at the same time in both sexes. So that here we have a structure, developed at a most unusually early age in one species of the family, and likewise common to both sexes in this one species alone. In several kinds of antelopes, only the males are provided with horns, whilst in the greater number both sexes bear horns. With respect to the period of development, Mr. Blyth informs me that there was at one time in the Zoological Gardens a young koodoo (Ant. strepsiceros), of which the males alone are horned, and also the young of a closely-allied species, the eland (Ant. oreas), in which both sexes are horned. Now it is in strict conformity with our rule, that in the young male koodoo, although ten months old, the horns were remarkably small, considering the size ultimately attained by them; whilst in the young male eland, although only three months old, the horns were already very much larger than in the koodoo. It is also a noticeable fact that in the prong-horned antelope (40. Antilocapra Americana. I have to thank Dr. Canfield for information with respect to the horns of the female: see also his paper in 'Proceedings of the Zoological Society,' 1866, p. 109. Also Owen, 'Anatomy of Vertebrates,' vol. iii. p. 627), only a few of the females, about one in five, have horns, and these are in a rudimentary state, though sometimes above four inches long: so that as far as concerns the possession of horns by the males alone, this species is in an intermediate condition, and the horns do not appear until about five or six months after birth. Therefore in comparison with what little we know of the development of the horns in other antelopes, and from what we do know with respect to the horns of deer, cattle, etc., those of the prong-horned antelope appear at an intermediate period of life,--that is, not very early, as in cattle and sheep, nor very late, as in the larger deer and antelopes. The horns of sheep, goats, and cattle, which are well developed in both sexes, though not quite equal in size, can be felt, or even seen, at birth or soon afterwards. (41. I have been assured that the horns of the sheep in North Wales can always be felt, and are sometimes even an inch in length, at birth. Youatt says ('Cattle,' 1834, p. 277), that the prominence of the frontal bone in cattle penetrates the cutis at birth, and that the horny matter is soon formed over it.) Our rule, however, seems to fail in some breeds of sheep, for instance merinos, in which the rams alone are horned; for I cannot find on enquiry (42. I am greatly indebted to Prof. Victor Carus for having made enquiries for me, from the highest authorities, with respect to the merino sheep of Saxony. On the Guinea coast of Africa there is, however, a breed of sheep in which, as with merinos, the rams alone bear horns; and Mr. Winwood Reade informs me that in one case observed by him, a young ram, born on Feb. 10th, first shewed horns on March 6th, so that in this instance, in conformity with rule, the development of the horns occurred at a later period of life than in Welsh sheep, in which both sexes are horned.), that the horns are developed later in life in this breed than in ordinary sheep in which both sexes are horned. But with domesticated sheep the presence or absence of horns is not a firmly fixed character; for a certain proportion of the merino ewes bear small horns, and some of the rams are hornless; and in most breeds hornless ewes are occasionally produced. Dr. W. Marshall has lately made a special study of the protuberances so common on the heads of birds (43. '�ber die knochernen Schädelhöcker der Vögel,' in the 'Niederland. Archiv fur Zoologie,' B.i. Heft 2, 1872.), and he comes to the following conclusion:--that with those species in which they are confined to the males, they are developed late in life; whereas with those species in which they are common to the two sexes, they are developed at a very early period. This is certainly a striking confirmation of my two laws of inheritance. In most of the species of the splendid family of the Pheasants, the males differ conspicuously from the females, and they acquire their ornaments at a rather late period of life. The eared pheasant (Crossoptilon auritum), however, offers a remarkable exception, for both sexes possess the fine caudal plumes, the large ear-tufts and the crimson velvet about the head; I find that all these characters appear very early in life in accordance with rule. The adult male can, however, be distinguished from the adult female by the presence of spurs; and conformably with our rule, these do not begin to be developed before the age of six months, as I am assured by Mr. Bartlett, and even at this age, the two sexes can hardly be distinguished. (44. In the common peacock (Pavo cristatus) the male alone possesses spurs, whilst both sexes of the Java Peacock (P. muticus) offer the unusual case of being furnished with spurs. Hence I fully expected that in the latter species they would have been developed earlier in life than in the common peacock; but M. Hegt of Amsterdam informs me, that with young birds of the previous year, of both species, compared on April 23rd, 1869, there was no difference in the development of the spurs. The spurs, however, were as yet represented merely by slight knobs or elevations. I presume that I should have been informed if any difference in the rate of development had been observed subsequently.) The male and female Peacock differ conspicuously from each other in almost every part of their plumage, except in the elegant head-crest, which is common to both sexes; and this is developed very early in life, long before the other ornaments, which are confined to the male. The wild-duck offers an analogous case, for the beautiful green speculum on the wings is common to both sexes, though duller and somewhat smaller in the female, and it is developed early in life, whilst the curled tail-feathers and other ornaments of the male are developed later. (45. In some other species of the Duck family the speculum differs in a greater degree in the two sexes; but I have not been able to discover whether its full development occurs later in life in the males of such species, than in the male of the common duck, as ought to be the case according to our rule. With the allied Mergus cucullatus we have, however, a case of this kind: the two sexes differ conspicuously in general plumage, and to a considerable degree in the speculum, which is pure white in the male and greyish-white in the female. Now the young males at first entirely resemble the females, and have a greyish-white speculum, which becomes pure white at an earlier age than that at which the adult male acquires his other and more strongly-marked sexual differences: see Audubon, 'Ornithological Biography,' vol. iii. 1835, pp. 249-250.) Between such extreme cases of close sexual resemblance and wide dissimilarity, as those of the Crossoptilon and peacock, many intermediate ones could be given, in which the characters follow our two rules in their order of development. As most insects emerge from the pupal state in a mature condition, it is doubtful whether the period of development can determine the transference of their characters to one or to both sexes. But we do not know that the coloured scales, for instance, in two species of butterflies, in one of which the sexes differ in colour, whilst in the other they are alike, are developed at the same relative age in the cocoon. Nor do we know whether all the scales are simultaneously developed on the wings of the same species of butterfly, in which certain coloured marks are confined to one sex, whilst others are common to both sexes. A difference of this kind in the period of development is not so improbable as it may at first appear; for with the Orthoptera, which assume their adult state, not by a single metamorphosis, but by a succession of moults, the young males of some species at first resemble the females, and acquire their distinctive masculine characters only at a later moult. Strictly analogous cases occur at the successive moults of certain male crustaceans. We have as yet considered the transference of characters, relatively to their period of development, only in species in a natural state; we will now turn to domesticated animals, and first touch on monstrosities and diseases. The presence of supernumerary digits, and the absence of certain phalanges, must be determined at an early embryonic period--the tendency to profuse bleeding is at least congenital, as is probably colour-blindness--yet these peculiarities, and other similar ones, are often limited in their transmission to one sex; so that the rule that characters, developed at an early period, tend to be transmitted to both sexes, here wholly fails. But this rule, as before remarked, does not appear to be nearly so general as the converse one, namely, that characters which appear late in life in one sex are transmitted exclusively to the same sex. From the fact of the above abnormal peculiarities becoming attached to one sex, long before the sexual functions are active, we may infer that there must be some difference between the sexes at an extremely early age. With respect to sexually-limited diseases, we know too little of the period at which they originate, to draw any safe conclusion. Gout, however, seems to fall under our rule, for it is generally caused by intemperance during manhood, and is transmitted from the father to his sons in a much more marked manner than to his daughters. In the various domestic breeds of sheep, goats, and cattle, the males differ from their respective females in the shape or development of their horns, forehead, mane, dewlap, tail, and hump on the shoulders; and these peculiarities, in accordance with our rule, are not fully developed until a rather late period of life. The sexes of dogs do not differ, except that in certain breeds, especially in the Scotch deer-hound, the male is much larger and heavier than the female; and, as we shall see in a future chapter, the male goes on increasing in size to an unusually late period of life, which, according to rule, will account for his increased size being transmitted to his male offspring alone. On the other hand, the tortoise-shell colour, which is confined to female cats, is quite distinct at birth, and this case violates the rule. There is a breed of pigeons in which the males alone are streaked with black, and the streaks can be detected even in the nestlings; but they become more conspicuous at each successive moult, so that this case partly opposes and partly supports the rule. With the English Carrier and Pouter pigeons, the full development of the wattle and the crop occurs rather late in life, and conformably with the rule, these characters are transmitted in full perfection to the males alone. The following cases perhaps come within the class previously alluded to, in which both sexes have varied in the same manner at a rather late period of life, and have consequently transferred their new characters to both sexes at a corresponding late period; and if so, these cases are not opposed to our rule:--there exist sub-breeds of the pigeon, described by Neumeister (46. 'Das Ganze der Taubenzucht,' 1837, ss. 21, 24. For the case of the streaked pigeons, see Dr. Chapuis, 'Le pigeon voyageur Belge,' 1865, p. 87.), in which both sexes change their colour during two or three moults (as is likewise the case with the Almond Tumbler); nevertheless, these changes, though occurring rather late in life, are common to both sexes. One variety of the Canary-bird, namely the London Prize, offers a nearly analogous case. With the breeds of the Fowl the inheritance of various characters by one or both sexes, seems generally determined by the period at which such characters are developed. Thus in all the many breeds in which the adult male differs greatly in colour from the female, as well as from the wild parent-species, he differs also from the young male, so that the newly-acquired characters must have appeared at a rather late period of life. On the other hand, in most of the breeds in which the two sexes resemble each other, the young are coloured in nearly the same manner as their parents, and this renders it probable that their colours first appeared early in life. We have instances of this fact in all black and white breeds, in which the young and old of both sexes are alike; nor can it be maintained that there is something peculiar in a black or white plumage, which leads to its transference to both sexes; for the males alone of many natural species are either black or white, the females being differently coloured. With the so-called Cuckoo sub-breeds of the fowl, in which the feathers are transversely pencilled with dark stripes, both sexes and the chickens are coloured in nearly the same manner. The laced plumage of the Sebright bantam is the same in both sexes, and in the young chickens the wing-feathers are distinctly, though imperfectly laced. Spangled Hamburgs, however, offer a partial exception; for the two sexes, though not quite alike, resemble each other more closely than do the sexes of the aboriginal parent-species; yet they acquire their characteristic plumage late in life, for the chickens are distinctly pencilled. With respect to other characters besides colour, in the wild-parent species and in most of the domestic breeds, the males alone possess a well-developed comb; but in the young of the Spanish fowl it is largely developed at a very early age, and, in accordance with this early development in the male, it is of unusual size in the adult female. In the Game breeds pugnacity is developed at a wonderfully early age, of which curious proofs could be given; and this character is transmitted to both sexes, so that the hens, from their extreme pugnacity, are now generally exhibited in separate pens. With the Polish breeds the bony protuberance of the skull which supports the crest is partially developed even before the chickens are hatched, and the crest itself soon begins to grow, though at first feebly (47. For full particulars and references on all these points respecting the several breeds of the Fowl, see 'Variation of Animals and Plants under Domestication,' vol. i. pp. 250, 256. In regard to the higher animals, the sexual differences which have arisen under domestication are described in the same work under the head of each species.); and in this breed the adults of both sexes are characterised by a great bony protuberance and an immense crest. Finally, from what we have now seen of the relation which exists in many natural species and domesticated races, between the period of the development of their characters and the manner of their transmission--for example, the striking fact of the early growth of the horns in the reindeer, in which both sexes bear horns, in comparison with their much later growth in the other species in which the male alone bears horns--we may conclude that one, though not the sole cause of characters being exclusively inherited by one sex, is their development at a late age. And secondly, that one, though apparently a less efficient cause of characters being inherited by both sexes, is their development at an early age, whilst the sexes differ but little in constitution. It appears, however, that some difference must exist between the sexes even during a very early embryonic period, for characters developed at this age not rarely become attached to one sex. SUMMARY AND CONCLUDING REMARKS. From the foregoing discussion on the various laws of inheritance, we learn that the characters of the parents often, or even generally, tend to become developed in the offspring of the same sex, at the same age, and periodically at the same season of the year, in which they first appeared in the parents. But these rules, owing to unknown causes, are far from being fixed. Hence during the modification of a species, the successive changes may readily be transmitted in different ways; some to one sex, and some to both; some to the offspring at one age, and some to the offspring at all ages. Not only are the laws of inheritance extremely complex, but so are the causes which induce and govern variability. The variations thus induced are preserved and accumulated by sexual selection, which is in itself an extremely complex affair, depending, as it does, on the ardour in love, the courage, and the rivalry of the males, as well as on the powers of perception, the taste, and will of the female. Sexual selection will also be largely dominated by natural selection tending towards the general welfare of the species. Hence the manner in which the individuals of either or both sexes have been affected through sexual selection cannot fail to be complex in the highest degree. When variations occur late in life in one sex, and are transmitted to the same sex at the same age, the other sex and the young are left unmodified. When they occur late in life, but are transmitted to both sexes at the same age, the young alone are left unmodified. Variations, however, may occur at any period of life in one sex or in both, and be transmitted to both sexes at all ages, and then all the individuals of the species are similarly modified. In the following chapters it will be seen that all these cases frequently occur in nature. Sexual selection can never act on any animal before the age for reproduction arrives. From the great eagerness of the male it has generally acted on this sex and not on the females. The males have thus become provided with weapons for fighting with their rivals, with organs for discovering and securely holding the female, and for exciting or charming her. When the sexes differ in these respects, it is also, as we have seen, an extremely general law that the adult male differs more or less from the young male; and we may conclude from this fact that the successive variations, by which the adult male became modified, did not generally occur much before the age for reproduction. Whenever some or many of the variations occurred early in life, the young males would partake more or less of the characters of the adult males; and differences of this kind between the old and young males may be observed in many species of animals. It is probable that young male animals have often tended to vary in a manner which would not only have been of no use to them at an early age, but would have been actually injurious--as by acquiring bright colours, which would render them conspicuous to their enemies, or by acquiring structures, such as great horns, which would expend much vital force in their development. Variations of this kind occurring in the young males would almost certainly be eliminated through natural selection. With the adult and experienced males, on the other hand, the advantages derived from the acquisition of such characters, would more than counterbalance some exposure to danger, and some loss of vital force. As variations which give to the male a better chance of conquering other males, or of finding, securing, or charming the opposite sex, would, if they happened to arise in the female, be of no service to her, they would not be preserved in her through sexual selection. We have also good evidence with domesticated animals, that variations of all kinds are, if not carefully selected, soon lost through intercrossing and accidental deaths. Consequently in a state of nature, if variations of the above kind chanced to arise in the female line, and to be transmitted exclusively in this line, they would be extremely liable to be lost. If, however, the females varied and transmitted their newly acquired characters to their offspring of both sexes, the characters which were advantageous to the males would be preserved by them through sexual selection, and the two sexes would in consequence be modified in the same manner, although such characters were of no use to the females: but I shall hereafter have to recur to these more intricate contingencies. Lastly, the females may acquire, and apparently have often acquired by transference, characters from the male sex. As variations occurring later in life, and transmitted to one sex alone, have incessantly been taken advantage of and accumulated through sexual selection in relation to the reproduction of the species; therefore it appears, at first sight, an unaccountable fact that similar variations have not frequently been accumulated through natural selection, in relation to the ordinary habits of life. If this had occurred, the two sexes would often have been differently modified, for the sake, for instance, of capturing prey or of escaping from danger. Differences of this kind between the two sexes do occasionally occur, especially in the lower classes. But this implies that the two sexes follow different habits in their struggles for existence, which is a rare circumstance with the higher animals. The case, however, is widely different with the reproductive functions, in which respect the sexes necessarily differ. For variations in structure which are related to these functions, have often proved of value to one sex, and from having arisen at a late period of life, have been transmitted to one sex alone; and such variations, thus preserved and transmitted, have given rise to secondary sexual characters. In the following chapters, I shall treat of the secondary sexual characters in animals of all classes, and shall endeavour in each case to apply the principles explained in the present chapter. The lowest classes will detain us for a very short time, but the higher animals, especially birds, must be treated at considerable length. It should be borne in mind that for reasons already assigned, I intend to give only a few illustrative instances of the innumerable structures by the aid of which the male finds the female, or, when found, holds her. On the other hand, all structures and instincts by the aid of which the male conquers other males, and by which he allures or excites the female, will be fully discussed, as these are in many ways the most interesting. SUPPLEMENT ON THE PROPORTIONAL NUMBERS OF THE TWO SEXES IN ANIMALS BELONGING TO VARIOUS CLASSES. As no one, as far as I can discover, has paid attention to the relative numbers of the two sexes throughout the animal kingdom, I will here give such materials as I have been able to collect, although they are extremely imperfect. They consist in only a few instances of actual enumeration, and the numbers are not very large. As the proportions are known with certainty only in mankind, I will first give them as a standard of comparison. MAN. In England during ten years (from 1857 to 1866) the average number of children born alive yearly was 707,120, in the proportion of 104.5 males to 100 females. But in 1857 the male births throughout England were as 105.2, and in 1865 as 104.0 to 100. Looking to separate districts, in Buckinghamshire (where about 5000 children are annually born) the MEAN proportion of male to female births, during the whole period of the above ten years, was as 102.8 to 100; whilst in N. Wales (where the average annual births are 12,873) it was as high as 106.2 to 100. Taking a still smaller district, viz., Rutlandshire (where the annual births average only 739), in 1864 the male births were as 114.6, and in 1862 as only 97.0 to 100; but even in this small district the average of the 7385 births during the whole ten years, was as 104.5 to 100: that is in the same ratio as throughout England. (48. 'Twenty-ninth Annual Report of the Registrar-General for 1866.' In this report (p. xii.) a special decennial table is given.) The proportions are sometimes slightly disturbed by unknown causes; thus Prof. Faye states "that in some districts of Norway there has been during a decennial period a steady deficiency of boys, whilst in others the opposite condition has existed." In France during forty-four years the male to the female births have been as 106.2 to 100; but during this period it has occurred five times in one department, and six times in another, that the female births have exceeded the males. In Russia the average proportion is as high as 108.9, and in Philadelphia in the United States as 110.5 to 100. (49. For Norway and Russia, see abstract of Prof. Faye's researches, in 'British and Foreign Medico-Chirurg. Review,' April 1867, pp. 343, 345. For France, the 'Annuaire pour l'An 1867,' p. 213. For Philadelphia, Dr. Stockton Hough, 'Social Science Assoc.' 1874. For the Cape of Good Hope, Quetelet as quoted by Dr. H.H. Zouteveen, in the Dutch Translation of this work (vol. i. p. 417), where much information is given on the proportion of the sexes.) The average for Europe, deduced by Bickes from about seventy million births, is 106 males to 100 females. On the other hand, with white children born at the Cape of Good Hope, the proportion of males is so low as to fluctuate during successive years between 90 and 99 males for every 100 females. It is a singular fact that with Jews the proportion of male births is decidedly larger than with Christians: thus in Prussia the proportion is as 113, in Breslau as 114, and in Livonia as 120 to 100; the Christian births in these countries being the same as usual, for instance, in Livonia as 104 to 100. (50. In regard to the Jews, see M. Thury, 'La Loi de Production des Sexes,' 1863, p. 25.) Prof. Faye remarks that "a still greater preponderance of males would be met with, if death struck both sexes in equal proportion in the womb and during birth. But the fact is, that for every 100 still-born females, we have in several countries from 134.6 to 144.9 still-born males. During the first four or five years of life, also, more male children die than females, for example in England, during the first year, 126 boys die for every 100 girls--a proportion which in France is still more unfavourable." (51. 'British and Foreign Medico-Chirurg. Review,' April 1867, p. 343. Dr. Stark also remarks ('Tenth Annual Report of Births, Deaths, etc., in Scotland,' 1867, p. xxviii.) that "These examples may suffice to show that, at almost every stage of life, the males in Scotland have a greater liability to death and a higher death-rate than the females. The fact, however, of this peculiarity being most strongly developed at that infantile period of life when the dress, food, and general treatment of both sexes are alike, seems to prove that the higher male death-rate is an impressed, natural, and constitutional peculiarity due to sex alone.") Dr. Stockton Hough accounts for these facts in part by the more frequent defective development of males than of females. We have before seen that the male sex is more variable in structure than the female; and variations in important organs would generally be injurious. But the size of the body, and especially of the head, being greater in male than female infants is another cause: for the males are thus more liable to be injured during parturition. Consequently the still-born males are more numerous; and, as a highly competent judge, Dr. Crichton Browne (52. 'West Riding Lunatic Asylum Reports,' vol. i. 1871, p. 8. Sir J. Simpson has proved that the head of the male infant exceeds that of the female by 3/8ths of an inch in circumference, and by 1/8th in transverse diameter. Quetelet has shewn that woman is born smaller than man; see Dr. Duncan, 'Fecundity, Fertility, and Sterility,' 1871, p. 382.), believes, male infants often suffer in health for some years after birth. Owing to this excess in the death-rate of male children, both at birth and for some time subsequently, and owing to the exposure of grown men to various dangers, and to their tendency to emigrate, the females in all old-settled countries, where statistical records have been kept, are found to preponderate considerably over the males. (53. With the savage Guaranys of Paraguay, according to the accurate Azara ('Voyages dans l'Amerique merid.' tom. ii. 1809, pp. 60, 179), the women are to the men in the proportion of 14 to 13.) It seems at first sight a mysterious fact that in different nations, under different conditions and climates, in Naples, Prussia, Westphalia, Holland, France, England and the United States, the excess of male over female births is less when they are illegitimate than when legitimate. (54. Babbage, 'Edinburgh Journal of Science,' 1829, vol. i. p. 88; also p. 90, on still-born children. On illegitimate children in England, see 'Report of Registrar-General for 1866,' p. xv.) This has been explained by different writers in many different ways, as from the mothers being generally young, from the large proportion of first pregnancies, etc. But we have seen that male infants, from the large size of their heads, suffer more than female infants during parturition; and as the mothers of illegitimate children must be more liable than other women to undergo bad labours, from various causes, such as attempts at concealment by tight lacing, hard work, distress of mind, etc., their male infants would proportionably suffer. And this probably is the most efficient of all the causes of the proportion of males to females born alive being less amongst illegitimate children than amongst the legitimate. With most animals the greater size of the adult male than of the female, is due to the stronger males having conquered the weaker in their struggles for the possession of the females, and no doubt it is owing to this fact that the two sexes of at least some animals differ in size at birth. Thus we have the curious fact that we may attribute the more frequent deaths of male than female infants, especially amongst the illegitimate, at least in part to sexual selection. It has often been supposed that the relative age of the two parents determine the sex of the offspring; and Prof. Leuckart (55. Leuckart, in Wagner 'Handwörterbuch der Phys.' B. iv. 1853, s. 774.) has advanced what he considers sufficient evidence, with respect to man and certain domesticated animals, that this is one important though not the sole factor in the result. So again the period of impregnation relatively to the state of the female has been thought by some to be the efficient cause; but recent observations discountenance this belief. According to Dr. Stockton Hough (56. 'Social Science Association of Philadelphia,' 1874.), the season of the year, the poverty or wealth of the parents, residence in the country or in cities, the crossing of foreign immigrants, etc., all influence the proportion of the sexes. With mankind, polygamy has also been supposed to lead to the birth of a greater proportion of female infants; but Dr. J. Campbell (57. 'Anthropological Review,' April 1870, p. cviii.) carefully attended to this subject in the harems of Siam, and concludes that the proportion of male to female births is the same as from monogamous unions. Hardly any animal has been rendered so highly polygamous as the English race-horse, and we shall immediately see that his male and female offspring are almost exactly equal in number. I will now give the facts which I have collected with respect to the proportional numbers of the sexes of various animals; and will then briefly discuss how far selection has come into play in determining the result. HORSES. Mr. Tegetmeier has been so kind as to tabulate for me from the 'Racing Calendar' the births of race-horses during a period of twenty-one years, viz., from 1846 to 1867; 1849 being omitted, as no returns were that year published. The total births were 25,560 (58. During eleven years a record was kept of the number of mares which proved barren or prematurely slipped their foals; and it deserves notice, as shewing how infertile these highly-nurtured and rather closely-interbred animals have become, that not far from one-third of the mares failed to produce living foals. Thus during 1866, 809 male colts and 816 female colts were born, and 743 mares failed to produce offspring. During 1867, 836 males and 902 females were born, and 794 mares failed.), consisting of 12,763 males and 12,797 females, or in the proportion of 99.7 males to 100 females. As these numbers are tolerably large, and as they are drawn from all parts of England, during several years, we may with much confidence conclude that with the domestic horse, or at least with the race-horse, the two sexes are produced in almost equal numbers. The fluctuations in the proportions during successive years are closely like those which occur with mankind, when a small and thinly-populated area is considered; thus in 1856 the male horses were as 107.1, and in 1867 as only 92.6 to 100 females. In the tabulated returns the proportions vary in cycles, for the males exceeded the females during six successive years; and the females exceeded the males during two periods each of four years; this, however, may be accidental; at least I can detect nothing of the kind with man in the decennial table in the Registrar's Report for 1866. DOGS. During a period of twelve years, from 1857 to 1868, the births of a large number of greyhounds, throughout England, were sent to the 'Field' newspaper; and I am again indebted to Mr. Tegetmeier for carefully tabulating the results. The recorded births were 6878, consisting of 3605 males and 3273 females, that is, in the proportion of 110.1 males to 100 females. The greatest fluctuations occurred in 1864, when the proportion was as 95.3 males, and in 1867, as 116.3 males to 100 females. The above average proportion of 110.1 to 100 is probably nearly correct in the case of the greyhound, but whether it would hold with other domesticated breeds is in some degree doubtful. Mr. Cupples has enquired from several great breeders of dogs, and finds that all without exception believe that females are produced in excess; but he suggests that this belief may have arisen from females being less valued, and from the consequent disappointment producing a stronger impression on the mind. SHEEP. The sexes of sheep are not ascertained by agriculturists until several months after birth, at the period when the males are castrated; so that the following returns do not give the proportions at birth. Moreover, I find that several great breeders in Scotland, who annually raise some thousand sheep, are firmly convinced that a larger proportion of males than of females die during the first year or two. Therefore the proportion of males would be somewhat larger at birth than at the age of castration. This is a remarkable coincidence with what, as we have seen, occurs with mankind, and both cases probably depend on the same cause. I have received returns from four gentlemen in England who have bred Lowland sheep, chiefly Leicesters, during the last ten to sixteen years; they amount altogether to 8965 births, consisting of 4407 males and 4558 females; that is in the proportion of 96.7 males to 100 females. With respect to Cheviot and black-faced sheep bred in Scotland, I have received returns from six breeders, two of them on a large scale, chiefly for the years 1867-1869, but some of the returns extend back to 1862. The total number recorded amounts to 50,685, consisting of 25,071 males and 25,614 females or in the proportion of 97.9 males to 100 females. If we take the English and Scotch returns together, the total number amounts to 59,650, consisting of 29,478 males and 30,172 females, or as 97.7 to 100. So that with sheep at the age of castration the females are certainly in excess of the males, but probably this would not hold good at birth. (59. I am much indebted to Mr. Cupples for having procured for me the above returns from Scotland, as well as some of the following returns on cattle. Mr. R. Elliot, of Laighwood, first called my attention to the premature deaths of the males, --a statement subsequently confirmed by Mr. Aitchison and others. To this latter gentleman, and to Mr. Payan, I owe my thanks for large returns as to sheep.) Of CATTLE I have received returns from nine gentlemen of 982 births, too few to be trusted; these consisted of 477 bull-calves and 505 cow-calves; i.e., in the proportion of 94.4 males to 100 females. The Rev. W.D. Fox informs me that in 1867 out of 34 calves born on a farm in Derbyshire only one was a bull. Mr. Harrison Weir has enquired from several breeders of PIGS, and most of them estimate the male to the female births as about 7 to 6. This same gentleman has bred RABBITS for many years, and has noticed that a far greater number of bucks are produced than does. But estimations are of little value. Of mammalia in a state of nature I have been able to learn very little. In regard to the common rat, I have received conflicting statements. Mr. R. Elliot, of Laighwood, informs me that a rat-catcher assured him that he had always found the males in great excess, even with the young in the nest. In consequence of this, Mr. Elliot himself subsequently examined some hundred old ones, and found the statement true. Mr. F. Buckland has bred a large number of white rats, and he also believes that the males greatly exceed the females. In regard to Moles, it is said that "the males are much more numerous than the females" (60. Bell, 'History of British Quadrupeds,' p. 100.): and as the catching of these animals is a special occupation, the statement may perhaps be trusted. Sir A. Smith, in describing an antelope of S. Africa (61. 'Illustrations of the Zoology of S. Africa,' 1849, pl. 29.) (Kobus ellipsiprymnus), remarks, that in the herds of this and other species, the males are few in number compared with the females: the natives believe that they are born in this proportion; others believe that the younger males are expelled from the herds, and Sir A. Smith says, that though he has himself never seen herds consisting of young males alone, others affirm that this does occur. It appears probable that the young when expelled from the herd, would often fall a prey to the many beasts of prey of the country. BIRDS. With respect to the FOWL, I have received only one account, namely, that out of 1001 chickens of a highly-bred stock of Cochins, reared during eight years by Mr. Stretch, 487 proved males and 514 females; i.e., as 94.7 to 100. In regard to domestic pigeons there is good evidence either that the males are produced in excess, or that they live longer; for these birds invariably pair, and single males, as Mr. Tegetmeier informs me, can always be purchased cheaper than females. Usually the two birds reared from the two eggs laid in the same nest are a male and a female; but Mr. Harrison Weir, who has been so large a breeder, says that he has often bred two cocks from the same nest, and seldom two hens; moreover, the hen is generally the weaker of the two, and more liable to perish. With respect to birds in a state of nature, Mr. Gould and others (62. Brehm ('Thierleben,' B. iv. s. 990) comes to the same conclusion.) are convinced that the males are generally the more numerous; and as the young males of many species resemble the females, the latter would naturally appear to be the more numerous. Large numbers of pheasants are reared by Mr. Baker of Leadenhall from eggs laid by wild birds, and he informs Mr. Jenner Weir that four or five males to one female are generally produced. An experienced observer remarks (63. On the authority of L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 12, 132.), that in Scandinavia the broods of the capercailzie and black-cock contain more males than females; and that with the Dal-ripa (a kind of ptarmigan) more males than females attend the leks or places of courtship; but this latter circumstance is accounted for by some observers by a greater number of hen birds being killed by vermin. From various facts given by White of Selborne (64. 'Nat. Hist. of Selborne,' letter xxix. edit. of 1825, vol. i. p. 139.), it seems clear that the males of the partridge must be in considerable excess in the south of England; and I have been assured that this is the case in Scotland. Mr. Weir on enquiring from the dealers, who receive at certain seasons large numbers of ruffs (Machetes pugnax), was told that the males are much the more numerous. This same naturalist has also enquired for me from the birdcatchers, who annually catch an astonishing number of various small species alive for the London market, and he was unhesitatingly answered by an old and trustworthy man, that with the chaffinch the males are in large excess: he thought as high as 2 males to 1 female, or at least as high as 5 to 3. (65. Mr. Jenner Weir received similar information, on making enquiries during the following year. To shew the number of living chaffinches caught, I may mention that in 1869 there was a match between two experts, and one man caught in a day 62, and another 40, male chaffinches. The greatest number ever caught by one man in a single day was 70.) The males of the blackbird, he likewise maintained, were by far the more numerous, whether caught by traps or by netting at night. These statements may apparently be trusted, because this same man said that the sexes are about equal with the lark, the twite (Linaria montana), and goldfinch. On the other hand, he is certain that with the common linnet, the females preponderate greatly, but unequally during different years; during some years he has found the females to the males as four to one. It should, however, be borne in mind, that the chief season for catching birds does not begin till September, so that with some species partial migrations may have begun, and the flocks at this period often consist of hens alone. Mr. Salvin paid particular attention to the sexes of the humming-birds in Central America, and is convinced that with most of the species the males are in excess; thus one year he procured 204 specimens belonging to ten species, and these consisted of 166 males and of only 38 females. With two other species the females were in excess: but the proportions apparently vary either during different seasons or in different localities; for on one occasion the males of Campylopterus hemileucurus were to the females as 5 to 2, and on another occasion (66. 'Ibis,' vol. ii. p. 260, as quoted in Gould's 'Trochilidae,' 1861, p. 52. For the foregoing proportions, I am indebted to Mr. Salvin for a table of his results.) in exactly the reversed ratio. As bearing on this latter point, I may add, that Mr. Powys found in Corfu and Epirus the sexes of the chaffinch keeping apart, and "the females by far the most numerous"; whilst in Palestine Mr. Tristram found "the male flocks appearing greatly to exceed the female in number." (67. 'Ibis,' 1860, p. 137; and 1867, p. 369.) So again with the Quiscalus major, Mr. G. Taylor says, that in Florida there were "very few females in proportion to the males," (68. 'Ibis,' 1862, p. 187.) whilst in Honduras the proportion was the other way, the species there having the character of a polygamist. FISH. With fish the proportional numbers of the sexes can be ascertained only by catching them in the adult or nearly adult state; and there are many difficulties in arriving at any just conclusion. (69. Leuckart quotes Bloch (Wagner, 'Handwörterbuch der Phys.' B. iv. 1853, s. 775), that with fish there are twice as many males as females.) Infertile females might readily be mistaken for males, as Dr. Gunther has remarked to me in regard to trout. With some species the males are believed to die soon after fertilising the ova. With many species the males are of much smaller size than the females, so that a large number of males would escape from the same net by which the females were caught. M. Carbonnier (70. Quoted in the 'Farmer,' March 18, 1869, p. 369.), who has especially attended to the natural history of the pike (Esox lucius), states that many males, owing to their small size, are devoured by the larger females; and he believes that the males of almost all fish are exposed from this same cause to greater danger than the females. Nevertheless, in the few cases in which the proportional numbers have been actually observed, the males appear to be largely in excess. Thus Mr. R. Buist, the superintendent of the Stormontfield experiments, says that in 1865, out of 70 salmon first landed for the purpose of obtaining the ova, upwards of 60 were males. In 1867 he again "calls attention to the vast disproportion of the males to the females. We had at the outset at least ten males to one female." Afterwards females sufficient for obtaining ova were procured. He adds, "from the great proportion of the males, they are constantly fighting and tearing each other on the spawning-beds." (71. 'The Stormontfield Piscicultural Experiments,' 1866, p. 23. The 'Field' newspaper, June 29, 1867.) This disproportion, no doubt, can be accounted for in part, but whether wholly is doubtful, by the males ascending the rivers before the females. Mr. F. Buckland remarks in regard to trout, that "it is a curious fact that the males preponderate very largely in number over the females. It INVARIABLY happens that when the first rush of fish is made to the net, there will be at least seven or eight males to one female found captive. I cannot quite account for this; either the males are more numerous than the females, or the latter seek safety by concealment rather than flight." He then adds, that by carefully searching the banks sufficient females for obtaining ova can be found. (72. 'Land and Water,' 1868, p. 41.) Mr. H. Lee informs me that out of 212 trout, taken for this purpose in Lord Portsmouth's park, 150 were males and 62 females. The males of the Cyprinidae likewise seem to be in excess; but several members of this Family, viz., the carp, tench, bream and minnow, appear regularly to follow the practice, rare in the animal kingdom, of polyandry; for the female whilst spawning is always attended by two males, one on each side, and in the case of the bream by three or four males. This fact is so well known, that it is always recommended to stock a pond with two male tenches to one female, or at least with three males to two females. With the minnow, an excellent observer states, that on the spawning-beds the males are ten times as numerous as the females; when a female comes amongst the males, "she is immediately pressed closely by a male on each side; and when they have been in that situation for a time, are superseded by other two males." (73. Yarrell, 'Hist. British Fishes,' vol. i. 1826, p. 307; on the Cyprinus carpio, p. 331; on the Tinca vulgaris, p. 331; on the Abramis brama, p. 336. See, for the minnow (Leuciscus phoxinus), 'Loudon's Magazine of Natural History,' vol. v. 1832, p. 682.) INSECTS. In this great Class, the Lepidoptera almost alone afford means for judging of the proportional numbers of the sexes; for they have been collected with special care by many good observers, and have been largely bred from the egg or caterpillar state. I had hoped that some breeders of silk-moths might have kept an exact record, but after writing to France and Italy, and consulting various treatises, I cannot find that this has ever been done. The general opinion appears to be that the sexes are nearly equal, but in Italy, as I hear from Professor Canestrini, many breeders are convinced that the females are produced in excess. This same naturalist, however, informs me, that in the two yearly broods of the Ailanthus silk-moth (Bombyx cynthia), the males greatly preponderate in the first, whilst in the second the two sexes are nearly equal, or the females rather in excess. In regard to Butterflies in a state of nature, several observers have been much struck by the apparently enormous preponderance of the males. (74. Leuckart quotes Meinecke (Wagner, 'Handwörterbuch der Phys.' B. iv. 1853, s. 775) that the males of Butterflies are three or four times as numerous as the females.) Thus Mr. Bates (75. 'The Naturalist on the Amazons,' vol. ii. 1863, pp. 228, 347.), in speaking of several species, about a hundred in number, which inhabit the upper Amazons, says that the males are much more numerous than the females, even in the proportion of a hundred to one. In North America, Edwards, who had great experience, estimates in the genus Papilio the males to the females as four to one; and Mr. Walsh, who informed me of this statement, says that with P. turnus this is certainly the case. In South Africa, Mr. R. Trimen found the males in excess in 19 species (76. Four of these cases are given by Mr. Trimen in his 'Rhopalocera Africae Australis.'); and in one of these, which swarms in open places, he estimated the number of males as fifty to one female. With another species, in which the males are numerous in certain localities, he collected only five females during seven years. In the island of Bourbon, M. Maillard states that the males of one species of Papilio are twenty times as numerous as the females. (77. Quoted by Trimen, 'Transactions of the Ent. Society,' vol. v. part iv. 1866, p. 330.) Mr. Trimen informs me that as far as he has himself seen, or heard from others, it is rare for the females of any butterfly to exceed the males in number; but three South African species perhaps offer an exception. Mr. Wallace (78. 'Transactions, Linnean Society,' vol. xxv. p. 37.) states that the females of Ornithoptera croesus, in the Malay archipelago, are more common and more easily caught than the males; but this is a rare butterfly. I may here add, that in Hyperythra, a genus of moths, Guenee says, that from four to five females are sent in collections from India for one male. When this subject of the proportional numbers of the sexes of insects was brought before the Entomological Society (79. 'Proceedings, Entomological Society,' Feb. 17, 1868.), it was generally admitted that the males of most Lepidoptera, in the adult or imago state, are caught in greater numbers than the females: but this fact was attributed by various observers to the more retiring habits of the females, and to the males emerging earlier from the cocoon. This latter circumstance is well known to occur with most Lepidoptera, as well as with other insects. So that, as M. Personnat remarks, the males of the domesticated Bombyx Yamamai, are useless at the beginning of the season, and the females at the end, from the want of mates. (80. Quoted by Dr. Wallace in 'Proceedings, Entomological Society,' 3rd series, vol. v. 1867, p. 487.) I cannot, however, persuade myself that these causes suffice to explain the great excess of males, in the above cases of certain butterflies which are extremely common in their native countries. Mr. Stainton, who has paid very close attention during many years to the smaller moths, informs me that when he collected them in the imago state, he thought that the males were ten times as numerous as the females, but that since he has reared them on a large scale from the caterpillar state, he is convinced that the females are the more numerous. Several entomologists concur in this view. Mr. Doubleday, however, and some others, take an opposite view, and are convinced that they have reared from the eggs and caterpillars a larger proportion of males than of females. Besides the more active habits of the males, their earlier emergence from the cocoon, and in some cases their frequenting more open stations, other causes may be assigned for an apparent or real difference in the proportional numbers of the sexes of Lepidoptera, when captured in the imago state, and when reared from the egg or caterpillar state. I hear from Professor Canestrini, that it is believed by many breeders in Italy, that the female caterpillar of the silk-moth suffers more from the recent disease than the male; and Dr. Staudinger informs me that in rearing Lepidoptera more females die in the cocoon than males. With many species the female caterpillar is larger than the male, and a collector would naturally choose the finest specimens, and thus unintentionally collect a larger number of females. Three collectors have told me that this was their practice; but Dr. Wallace is sure that most collectors take all the specimens which they can find of the rarer kinds, which alone are worth the trouble of rearing. Birds when surrounded by caterpillars would probably devour the largest; and Professor Canestrini informs me that in Italy some breeders believe, though on insufficient evidence, that in the first broods of the Ailanthus silk-moth, the wasps destroy a larger number of the female than of the male caterpillars. Dr. Wallace further remarks that female caterpillars, from being larger than the males, require more time for their development, and consume more food and moisture: and thus they would be exposed during a longer time to danger from ichneumons, birds, etc., and in times of scarcity would perish in greater numbers. Hence it appears quite possible that in a state of nature, fewer female Lepidoptera may reach maturity than males; and for our special object we are concerned with their relative numbers at maturity, when the sexes are ready to propagate their kind. The manner in which the males of certain moths congregate in extraordinary numbers round a single female, apparently indicates a great excess of males, though this fact may perhaps be accounted for by the earlier emergence of the males from their cocoons. Mr. Stainton informs me that from twelve to twenty males, may often be seen congregated round a female Elachista rufocinerea. It is well known that if a virgin Lasiocampa quercus or Saturnia carpini be exposed in a cage, vast numbers of males collect round her, and if confined in a room will even come down the chimney to her. Mr. Doubleday believes that he has seen from fifty to a hundred males of both these species attracted in the course of a single day by a female in confinement. In the Isle of Wight Mr. Trimen exposed a box in which a female of the Lasiocampa had been confined on the previous day, and five males soon endeavoured to gain admittance. In Australia, Mr. Verreaux, having placed the female of a small Bombyx in a box in his pocket, was followed by a crowd of males, so that about 200 entered the house with him. (81. Blanchard, 'Metamorphoses, Moeurs des Insectes,' 1868, pp. 225-226.) Mr. Doubleday has called my attention to M. Staudinger's (82. 'Lepidopteren-Doubletten Liste,' Berlin, No. x. 1866.) list of Lepidoptera, which gives the prices of the males and females of 300 species or well-marked varieties of butterflies (Rhopalocera). The prices for both sexes of the very common species are of course the same; but in 114 of the rarer species they differ; the males being in all cases, excepting one, the cheaper. On an average of the prices of the 113 species, the price of the male to that of the female is as 100 to 149; and this apparently indicates that inversely the males exceed the females in the same proportion. About 2000 species or varieties of moths (Heterocera) are catalogued, those with wingless females being here excluded on account of the difference in habits between the two sexes: of these 2000 species, 141 differ in price according to sex, the males of 130 being cheaper, and those of only 11 being dearer than the females. The average price of the males of the 130 species, to that of the females, is as 100 to 143. With respect to the butterflies in this priced list, Mr. Doubleday thinks (and no man in England has had more experience), that there is nothing in the habits of the species which can account for the difference in the prices of the two sexes, and that it can be accounted for only by an excess in the number of the males. But I am bound to add that Dr. Staudinger informs me, that he is himself of a different opinion. He thinks that the less active habits of the females and the earlier emergence of the males will account for his collectors securing a larger number of males than of females, and consequently for the lower prices of the former. With respect to specimens reared from the caterpillar-state, Dr. Staudinger believes, as previously stated, that a greater number of females than of males die whilst confined to the cocoons. He adds that with certain species one sex seems to preponderate over the other during certain years. Of direct observations on the sexes of Lepidoptera, reared either from eggs or caterpillars, I have received only the few following cases: (See following table.) So that in these eight lots of cocoons and eggs, males were produced in excess. Taken together the proportion of males is as 122.7 to 100 females. But the numbers are hardly large enough to be trustworthy. On the whole, from these various sources of evidence, all pointing in the same direction, I infer that with most species of Lepidoptera, the mature males generally exceed the females in number, whatever the proportions may be at their first emergence from the egg. Males Females The Rev. J. Hellins* of Exeter reared, during 1868, imagos of 73 species, which consisted of 153 137 Mr. Albert Jones of Eltham reared, during 1868, imagos of 9 species, which consisted of 159 126 During 1869 he reared imagos from 4 species consisting of 114 112 Mr. Buckler of Emsworth, Hants, during 1869, reared imagos from 74 species, consisting of 180 169 Dr. Wallace of Colchester reared from one brood of Bombyx cynthia 52 48 Dr. Wallace raised, from cocoons of Bombyx Pernyi sent from China, during 1869 224 123 Dr. Wallace raised, during 1868 and 1869, from two lots of cocoons of Bombyx yamamai 52 46 Total 934 761 (*83. This naturalist has been so kind as to send me some results from former years, in which the females seemed to preponderate; but so many of the figures were estimates, that I found it impossible to tabulate them.) With reference to the other Orders of insects, I have been able to collect very little reliable information. With the stag-beetle (Lucanus cervus) "the males appear to be much more numerous than the females"; but when, as Cornelius remarked during 1867, an unusual number of these beetles appeared in one part of Germany, the females appeared to exceed the males as six to one. With one of the Elateridae, the males are said to be much more numerous than the females, and "two or three are often found united with one female (84. Gunther's 'Record of Zoological Literature,' 1867, p. 260. On the excess of female Lucanus, ibid, p. 250. On the males of Lucanus in England, Westwood,' 'Modern Classification of Insects,' vol. i. p. 187. On the Siagonium, ibid. p. 172.); so that here polyandry seems to prevail." With Siagonium (Staphylinidae), in which the males are furnished with horns, "the females are far more numerous than the opposite sex." Mr. Janson stated at the Entomological Society that the females of the bark feeding Tomicus villosus are so common as to be a plague, whilst the males are so rare as to be hardly known. It is hardly worth while saying anything about the proportion of the sexes in certain species and even groups of insects, for the males are unknown or very rare, and the females are parthenogenetic, that is, fertile without sexual union; examples of this are afforded by several of the Cynipidae. (85. Walsh in 'The American Entomologist,' vol. i. 1869, p. 103. F. Smith, 'Record of Zoological Lit.' 1867, p. 328.) In all the gall-making Cynipidae known to Mr. Walsh, the females are four or five times as numerous as the males; and so it is, as he informs me, with the gall-making Cecidomyiidae (Diptera). With some common species of Saw-flies (Tenthredinae) Mr. F. Smith has reared hundreds of specimens from larvae of all sizes, but has never reared a single male; on the other hand, Curtis says (86. 'Farm Insects,' pp. 45-46.), that with certain species (Athalia), bred by him, the males were to the females as six to one; whilst exactly the reverse occurred with the mature insects of the same species caught in the fields. In the family of bees, Hermann Müller (87. 'Anwendung der Darwin'schen Lehre,' Verh. d. n. Jahrg., xxiv.), collected a large number of specimens of many species, and reared others from the cocoons, and counted the sexes. He found that the males of some species greatly exceeded the females in number; in others the reverse occurred; and in others the two sexes were nearly equal. But as in most cases the males emerge from the cocoons before the females, they are at the commencement of the breeding-season practically in excess. Müller also observed that the relative number of the two sexes in some species differed much in different localities. But as H. Müller has himself remarked to me, these remarks must be received with some caution, as one sex might more easily escape observation than the other. Thus his brother Fritz Müller has noticed in Brazil that the two sexes of the same species of bee sometimes frequent different kinds of flowers. With respect to the Orthoptera, I know hardly anything about the relative number of the sexes: Korte (88. 'Die Strich, Zug oder Wanderheuschrecke,' 1828, p. 20.), however, says that out of 500 locusts which he examined, the males were to the females as five to six. With the Neuroptera, Mr. Walsh states that in many, but by no means in all the species of the Odonatous group, there is a great overplus of males: in the genus Hetaerina, also, the males are generally at least four times as numerous as the females. In certain species in the genus Gomphus the males are equally in excess, whilst in two other species, the females are twice or thrice as numerous as the males. In some European species of Psocus thousands of females may be collected without a single male, whilst with other species of the same genus both sexes are common. (89. 'Observations on N. American Neuroptera,' by H. Hagen and B.D. Walsh, 'Proceedings, Ent. Soc. Philadelphia,' Oct. 1863, pp. 168, 223, 239.) In England, Mr. MacLachlan has captured hundreds of the female Apatania muliebris, but has never seen the male; and of Boreus hyemalis only four or five males have been seen here. (90. 'Proceedings, Ent. Soc. London,' Feb. 17, 1868.) With most of these species (excepting the Tenthredinae) there is at present no evidence that the females are subject to parthenogenesis; and thus we see how ignorant we are of the causes of the apparent discrepancy in the proportion of the two sexes. In the other classes of the Articulata I have been able to collect still less information. With spiders, Mr. Blackwall, who has carefully attended to this class during many years, writes to me that the males from their more erratic habits are more commonly seen, and therefore appear more numerous. This is actually the case with a few species; but he mentions several species in six genera, in which the females appear to be much more numerous than the males. (91. Another great authority with respect to this class, Prof. Thorell of Upsala ('On European Spiders,' 1869-70, part i. p. 205), speaks as if female spiders were generally commoner than the males.) The small size of the males in comparison with the females (a peculiarity which is sometimes carried to an extreme degree), and their widely different appearance, may account in some instances for their rarity in collections. (92. See, on this subject, Mr. O.P. Cambridge, as quoted in 'Quarterly Journal of Science,' 1868, page 429.) Some of the lower Crustaceans are able to propagate their kind sexually, and this will account for the extreme rarity of the males; thus von Siebold (93. 'Beiträge zur Parthenogenesis,' p. 174.) carefully examined no less than 13,000 specimens of Apus from twenty-one localities, and amongst these he found only 319 males. With some other forms (as Tanais and Cypris), as Fritz Müller informs me, there is reason to believe that the males are much shorter-lived than the females; and this would explain their scarcity, supposing the two sexes to be at first equal in number. On the other hand, Müller has invariably taken far more males than females of the Diastylidae and of Cypridina on the shores of Brazil: thus with a species in the latter genus, 63 specimens caught the same day included 57 males; but he suggests that this preponderance may be due to some unknown difference in the habits of the two sexes. With one of the higher Brazilian crabs, namely a Gelasimus, Fritz Müller found the males to be more numerous than the females. According to the large experience of Mr. C. Spence Bate, the reverse seems to be the case with six common British crabs, the names of which he has given me. THE PROPORTION OF THE SEXES IN RELATION TO NATURAL SELECTION. There is reason to suspect that in some cases man has by selection indirectly influenced his own sex-producing powers. Certain women tend to produce during their whole lives more children of one sex than of the other: and the same holds good of many animals, for instance, cows and horses; thus Mr. Wright of Yeldersley House informs me that one of his Arab mares, though put seven times to different horses, produced seven fillies. Though I have very little evidence on this head, analogy would lead to the belief, that the tendency to produce either sex would be inherited like almost every other peculiarity, for instance, that of producing twins; and concerning the above tendency a good authority, Mr. J. Downing, has communicated to me facts which seem to prove that this does occur in certain families of short-horn cattle. Col. Marshall (94. 'The Todas,' 1873, pp. 100, 111, 194, 196.) has recently found on careful examination that the Todas, a hill-tribe of India, consist of 112 males and 84 females of all ages--that is in a ratio of 133.3 males to 100 females. The Todas, who are polyandrous in their marriages, during former times invariably practised female infanticide; but this practice has now been discontinued for a considerable period. Of the children born within late years, the males are more numerous than the females, in the proportion of 124 to 100. Colonel Marshall accounts for this fact in the following ingenious manner. "Let us for the purpose of illustration take three families as representing an average of the entire tribe; say that one mother gives birth to six daughters and no sons; a second mother has six sons only, whilst the third mother has three sons and three daughters. The first mother, following the tribal custom, destroys four daughters and preserves two. The second retains her six sons. The third kills two daughters and keeps one, as also her three sons. We have then from the three families, nine sons and three daughters, with which to continue the breed. But whilst the males belong to families in which the tendency to produce sons is great, the females are of those of a converse inclination. Thus the bias strengthens with each generation, until, as we find, families grow to have habitually more sons than daughters." That this result would follow from the above form of infanticide seems almost certain; that is if we assume that a sex-producing tendency is inherited. But as the above numbers are so extremely scanty, I have searched for additional evidence, but cannot decide whether what I have found is trustworthy; nevertheless the facts are, perhaps, worth giving. The Maories of New Zealand have long practised infanticide; and Mr. Fenton (95. 'Aboriginal Inhabitants of New Zealand: Government Report,' 1859, p. 36.) states that he "has met with instances of women who have destroyed four, six, and even seven children, mostly females. However, the universal testimony of those best qualified to judge, is conclusive that this custom has for many years been almost extinct. Probably the year 1835 may be named as the period of its ceasing to exist." Now amongst the New Zealanders, as with the Todas, male births are considerably in excess. Mr. Fenton remarks (p. 30), "One fact is certain, although the exact period of the commencement of this singular condition of the disproportion of the sexes cannot be demonstratively fixed, it is quite clear that this course of decrease was in full operation during the years 1830 to 1844, when the non-adult population of 1844 was being produced, and has continued with great energy up to the present time." The following statements are taken from Mr. Fenton (p. 26), but as the numbers are not large, and as the census was not accurate, uniform results cannot be expected. It should be borne in mind in this and the following cases, that the normal state of every population is an excess of women, at least in all civilised countries, chiefly owing to the greater mortality of the male sex during youth, and partly to accidents of all kinds later in life. In 1858, the native population of New Zealand was estimated as consisting of 31,667 males and 24,303 females of all ages, that is in the ratio of 130.3 males to 100 females. But during this same year, and in certain limited districts, the numbers were ascertained with much care, and the males of all ages were here 753 and the females 616; that is in the ratio of 122.2 males to 100 females. It is more important for us that during this same year of 1858, the NON-ADULT males within the same district were found to be 178, and the NON-ADULT females 142, that is in the ratio of 125.3 to 100. It may be added that in 1844, at which period female infanticide had only lately ceased, the NON-ADULT males in one district were 281, and the NON-ADULT females only 194, that is in the ratio of 144.8 males to 100 females. In the Sandwich Islands, the males exceed the females in number. Infanticide was formerly practised there to a frightful extent, but was by no means confined to female infants, as is shewn by Mr. Ellis (96. 'Narrative of a Tour through Hawaii,' 1826, p. 298.), and as I have been informed by Bishop Staley and the Rev. Mr. Coan. Nevertheless, another apparently trustworthy writer, Mr. Jarves (97. 'History of the Sandwich Islands,' 1843, p. 93.), whose observations apply to the whole archipelago, remarks:--"Numbers of women are to be found, who confess to the murder of from three to six or eight children," and he adds, "females from being considered less useful than males were more often destroyed." From what is known to occur in other parts of the world, this statement is probable; but must be received with much caution. The practice of infanticide ceased about the year 1819, when idolatry was abolished and missionaries settled in the Islands. A careful census in 1839 of the adult and taxable men and women in the island of Kauai and in one district of Oahu (Jarves, p. 404), gives 4723 males and 3776 females; that is in the ratio of 125.08 to 100. At the same time the number of males under fourteen years in Kauai and under eighteen in Oahu was 1797, and of females of the same ages 1429; and here we have the ratio of 125.75 males to 100 females. In a census of all the islands in 1850 (98. This is given in the Rev. H.T. Cheever's 'Life in the Sandwich Islands,' 1851, p. 277.), the males of all ages amount to 36,272, and the females to 33,128, or as 109.49 to 100. The males under seventeen years amounted to 10,773, and the females under the same age to 9593, or as 112.3 to 100. From the census of 1872, the proportion of males of all ages (including half-castes) to females, is as 125.36 to 100. It must be borne in mind that all these returns for the Sandwich Islands give the proportion of living males to living females, and not of the births; and judging from all civilised countries the proportion of males would have been considerably higher if the numbers had referred to births. (99. Dr. Coulter, in describing ('Journal R. Geograph. Soc.' vol. v. 1835, p. 67) the state of California about the year 1830, says that the natives, reclaimed by the Spanish missionaries, have nearly all perished, or are perishing, although well treated, not driven from their native land, and kept from the use of spirits. He attributes this, in great part, to the undoubted fact that the men greatly exceed the women in number; but he does not know whether this is due to a failure of female offspring, or to more females dying during early youth. The latter alternative, according to all analogy, is very improbable. He adds that "infanticide, properly so called, is not common, though very frequent recourse is had to abortion." If Dr. Coulter is correct about infanticide, this case cannot be advanced in support of Colonel Marshall's view. From the rapid decrease of the reclaimed natives, we may suspect that, as in the cases lately given, their fertility has been diminished from changed habits of life. I had hoped to gain some light on this subject from the breeding of dogs; inasmuch as in most breeds, with the exception, perhaps, of greyhounds, many more female puppies are destroyed than males, just as with the Toda infants. Mr. Cupples assures me that this is usual with Scotch deer-hounds. Unfortunately, I know nothing of the proportion of the sexes in any breed, excepting greyhounds, and there the male births are to the females as 110.1 to 100. Now from enquiries made from many breeders, it seems that the females are in some respects more esteemed, though otherwise troublesome; and it does not appear that the female puppies of the best-bred dogs are systematically destroyed more than the males, though this does sometimes take place to a limited extent. Therefore I am unable to decide whether we can, on the above principles, account for the preponderance of male births in greyhounds. On the other hand, we have seen that with horses, cattle, and sheep, which are too valuable for the young of either sex to be destroyed, if there is any difference, the females are slightly in excess.) From the several foregoing cases we have some reason to believe that infanticide practised in the manner above explained, tends to make a male-producing race; but I am far from supposing that this practice in the case of man, or some analogous process with other species, has been the sole determining cause of an excess of males. There may be some unknown law leading to this result in decreasing races, which have already become somewhat infertile. Besides the several causes previously alluded to, the greater facility of parturition amongst savages, and the less consequent injury to their male infants, would tend to increase the proportion of live-born males to females. There does not, however, seem to be any necessary connection between savage life and a marked excess of males; that is if we may judge by the character of the scanty offspring of the lately existing Tasmanians and of the crossed offspring of the Tahitians now inhabiting Norfolk Island. As the males and females of many animals differ somewhat in habits and are exposed in different degrees to danger, it is probable that in many cases, more of one sex than of the other are habitually destroyed. But as far as I can trace out the complication of causes, an indiscriminate though large destruction of either sex would not tend to modify the sex-producing power of the species. With strictly social animals, such as bees or ants, which produce a vast number of sterile and fertile females in comparison with the males, and to whom this preponderance is of paramount importance, we can see that those communities would flourish best which contained females having a strong inherited tendency to produce more and more females; and in such cases an unequal sex-producing tendency would be ultimately gained through natural selection. With animals living in herds or troops, in which the males come to the front and defend the herd, as with the bisons of North America and certain baboons, it is conceivable that a male-producing tendency might be gained by natural selection; for the individuals of the better defended herds would leave more numerous descendants. In the case of mankind the advantage arising from having a preponderance of men in the tribe is supposed to be one chief cause of the practice of female infanticide. In no case, as far as we can see, would an inherited tendency to produce both sexes in equal numbers or to produce one sex in excess, be a direct advantage or disadvantage to certain individuals more than to others; for instance, an individual with a tendency to produce more males than females would not succeed better in the battle for life than an individual with an opposite tendency; and therefore a tendency of this kind could not be gained through natural selection. Nevertheless, there are certain animals (for instance, fishes and cirripedes) in which two or more males appear to be necessary for the fertilisation of the female; and the males accordingly largely preponderate, but it is by no means obvious how this male-producing tendency could have been acquired. I formerly thought that when a tendency to produce the two sexes in equal numbers was advantageous to the species, it would follow from natural selection, but I now see that the whole problem is so intricate that it is safer to leave its solution for the future. CHAPTER IX. SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL KINGDOM. These characters absent in the lowest classes--Brilliant colours--Mollusca --Annelids--Crustacea, secondary sexual characters strongly developed; dimorphism; colour; characters not acquired before maturity--Spiders, sexual colours of; stridulation by the males--Myriapoda. With animals belonging to the lower classes, the two sexes are not rarely united in the same individual, and therefore secondary sexual characters cannot be developed. In many cases where the sexes are separate, both are permanently attached to some support, and the one cannot search or struggle for the other. Moreover it is almost certain that these animals have too imperfect senses and much too low mental powers to appreciate each other's beauty or other attractions, or to feel rivalry. Hence in these classes or sub-kingdoms, such as the Protozoa, Coelenterata, Echinodermata, Scolecida, secondary sexual characters, of the kind which we have to consider, do not occur: and this fact agrees with the belief that such characters in the higher classes have been acquired through sexual selection, which depends on the will, desire, and choice of either sex. Nevertheless some few apparent exceptions occur; thus, as I hear from Dr. Baird, the males of certain Entozoa, or internal parasitic worms, differ slightly in colour from the females; but we have no reason to suppose that such differences have been augmented through sexual selection. Contrivances by which the male holds the female, and which are indispensable for the propagation of the species, are independent of sexual selection, and have been acquired through ordinary selection. Many of the lower animals, whether hermaphrodites or with separate sexes, are ornamented with the most brilliant tints, or are shaded and striped in an elegant manner; for instance, many corals and sea-anemones (Actiniae), some jelly-fish (Medusae, Porpita, etc.), some Planariae, many star-fishes, Echini, Ascidians, etc.; but we may conclude from the reasons already indicated, namely, the union of the two sexes in some of these animals, the permanently affixed condition of others, and the low mental powers of all, that such colours do not serve as a sexual attraction, and have not been acquired through sexual selection. It should be borne in mind that in no case have we sufficient evidence that colours have been thus acquired, except where one sex is much more brilliantly or conspicuously coloured than the other, and where there is no difference in habits between the sexes sufficient to account for their different colours. But the evidence is rendered as complete as it can ever be, only when the more ornamented individuals, almost always the males, voluntarily display their attractions before the other sex; for we cannot believe that such display is useless, and if it be advantageous, sexual selection will almost inevitably follow. We may, however, extend this conclusion to both sexes, when coloured alike, if their colours are plainly analogous to those of one sex alone in certain other species of the same group. How, then, are we to account for the beautiful or even gorgeous colours of many animals in the lowest classes? It appears doubtful whether such colours often serve as a protection; but that we may easily err on this head, will be admitted by every one who reads Mr. Wallace's excellent essay on this subject. It would not, for instance, at first occur to any one that the transparency of the Medusae, or jelly-fish, is of the highest service to them as a protection; but when we are reminded by Haeckel that not only the Medusae, but many floating Mollusca, crustaceans, and even small oceanic fishes partake of this same glass-like appearance, often accompanied by prismatic colours, we can hardly doubt that they thus escape the notice of pelagic birds and other enemies. M. Giard is also convinced (1. 'Archives de Zoolog. Exper.' Oct. 1872, p. 563.) that the bright tints of certain sponges and ascidians serve as a protection. Conspicuous colours are likewise beneficial to many animals as a warning to their would-be devourers that they are distasteful, or that they possess some special means of defence; but this subject will be discussed more conveniently hereafter. We can, in our ignorance of most of the lowest animals, only say that their bright tints result either from the chemical nature or the minute structure of their tissues, independently of any benefit thus derived. Hardly any colour is finer than that of arterial blood; but there is no reason to suppose that the colour of the blood is in itself any advantage; and though it adds to the beauty of the maiden's cheek, no one will pretend that it has been acquired for this purpose. So again with many animals, especially the lower ones, the bile is richly coloured; thus, as I am informed by Mr. Hancock, the extreme beauty of the Eolidae (naked sea-slugs) is chiefly due to the biliary glands being seen through the translucent integuments--this beauty being probably of no service to these animals. The tints of the decaying leaves in an American forest are described by every one as gorgeous; yet no one supposes that these tints are of the least advantage to the trees. Bearing in mind how many substances closely analogous to natural organic compounds have been recently formed by chemists, and which exhibit the most splendid colours, it would have been a strange fact if substances similarly coloured had not often originated, independently of any useful end thus gained, in the complex laboratory of living organisms. THE SUB-KINGDOM OF THE MOLLUSCA. Throughout this great division of the animal kingdom, as far as I can discover, secondary sexual characters, such as we are here considering, never occur. Nor could they be expected in the three lowest classes, namely, in the Ascidians, Polyzoa, and Brachiopods (constituting the Molluscoida of some authors), for most of these animals are permanently affixed to a support or have their sexes united in the same individual. In the Lamellibranchiata, or bivalve shells, hermaphroditism is not rare. In the next higher class of the Gasteropoda, or univalve shells, the sexes are either united or separate. But in the latter case the males never possess special organs for finding, securing, or charming the females, or for fighting with other males. As I am informed by Mr. Gwyn Jeffreys, the sole external difference between the sexes consists in the shell sometimes differing a little in form; for instance, the shell of the male periwinkle (Littorina littorea) is narrower and has a more elongated spire than that of the female. But differences of this nature, it may be presumed, are directly connected with the act of reproduction, or with the development of the ova. The Gasteropoda, though capable of locomotion and furnished with imperfect eyes, do not appear to be endowed with sufficient mental powers for the members of the same sex to struggle together in rivalry, and thus to acquire secondary sexual characters. Nevertheless with the pulmoniferous gasteropods, or land-snails, the pairing is preceded by courtship; for these animals, though hermaphrodites, are compelled by their structure to pair together. Agassiz remarks, "Quiconque a eu l'occasion d'observer les amours des limaçons, ne saurait mettre en doute la séduction deployée dans les mouvements et les allures qui préparent et accomplissent le double embrassement de ces hermaphrodites." (2. 'De l'Espèce et de la Class.' etc., 1869, p. 106.) These animals appear also susceptible of some degree of permanent attachment: an accurate observer, Mr. Lonsdale, informs me that he placed a pair of land-snails, (Helix pomatia), one of which was weakly, into a small and ill-provided garden. After a short time the strong and healthy individual disappeared, and was traced by its track of slime over a wall into an adjoining well-stocked garden. Mr. Lonsdale concluded that it had deserted its sickly mate; but after an absence of twenty-four hours it returned, and apparently communicated the result of its successful exploration, for both then started along the same track and disappeared over the wall. Even in the highest class of the Mollusca, the Cephalopoda or cuttle-fishes, in which the sexes are separate, secondary sexual characters of the present kind do not, as far as I can discover, occur. This is a surprising circumstance, as these animals possess highly-developed sense-organs and have considerable mental powers, as will be admitted by every one who has watched their artful endeavours to escape from an enemy. (3. See, for instance, the account which I have given in my 'Journal of Researches,' 1845, p. 7.) Certain Cephalopoda, however, are characterised by one extraordinary sexual character, namely that the male element collects within one of the arms or tentacles, which is then cast off, and clinging by its sucking-discs to the female, lives for a time an independent life. So completely does the cast-off arm resemble a separate animal, that it was described by Cuvier as a parasitic worm under the name of Hectocotyle. But this marvellous structure may be classed as a primary rather than as a secondary sexual character. Although with the Mollusca sexual selection does not seem to have come into play; yet many univalve and bivalve shells, such as volutes, cones, scallops, etc., are beautifully coloured and shaped. The colours do not appear in most cases to be of any use as a protection; they are probably the direct result, as in the lowest classes, of the nature of the tissues; the patterns and the sculpture of the shell depending on its manner of growth. The amount of light seems to be influential to a certain extent; for although, as repeatedly stated by Mr. Gwyn Jeffreys, the shells of some species living at a profound depth are brightly coloured, yet we generally see the lower surfaces, as well as the parts covered by the mantle, less highly-coloured than the upper and exposed surfaces. (4. I have given ('Geological Observations on Volcanic Islands,' 1844, p. 53) a curious instance of the influence of light on the colours of a frondescent incrustation, deposited by the surf on the coast-rocks of Ascension and formed by the solution of triturated sea-shells.) In some cases, as with shells living amongst corals or brightly-tinted seaweeds, the bright colours may serve as a protection. (5. Dr. Morse has lately discussed this subject in his paper on the 'Adaptive Coloration of Mollusca,' 'Proc. Boston Soc. of Nat. Hist.' vol. xiv. April 1871.) But that many of the nudibranch Mollusca, or sea-slugs, are as beautifully coloured as any shells, may be seen in Messrs. Alder and Hancock's magnificent work; and from information kindly given me by Mr. Hancock, it seems extremely doubtful whether these colours usually serve as a protection. With some species this may be the case, as with one kind which lives on the green leaves of algae, and is itself bright-green. But many brightly-coloured, white, or otherwise conspicuous species, do not seek concealment; whilst again some equally conspicuous species, as well as other dull-coloured kinds live under stones and in dark recesses. So that with these nudibranch molluscs, colour apparently does not stand in any close relation to the nature of the places which they inhabit. These naked sea-slugs are hermaphrodites, yet they pair together, as do land-snails, many of which have extremely pretty shells. It is conceivable that two hermaphrodites, attracted by each other's greater beauty, might unite and leave offspring which would inherit their parents' greater beauty. But with such lowly-organised creatures this is extremely improbable. Nor is it at all obvious how the offspring from the more beautiful pairs of hermaphrodites would have any advantage over the offspring of the less beautiful, so as to increase in number, unless indeed vigour and beauty generally coincided. We have not here the case of a number of males becoming mature before the females, with the more beautiful males selected by the more vigorous females. If, indeed, brilliant colours were beneficial to a hermaphrodite animal in relation to its general habits of life, the more brightly-tinted individuals would succeed best and would increase in number; but this would be a case of natural and not of sexual selection. SUB-KINGDOM OF THE VERMES: CLASS, ANNELIDA (OR SEA-WORMS). In this class, although the sexes, when separate, sometimes differ from each other in characters of such importance that they have been placed under distinct genera or even families, yet the differences do not seem of the kind which can be safely attributed to sexual selection. These animals are often beautifully coloured, but as the sexes do not differ in this respect, we are but little concerned with them. Even the Nemertians, though so lowly organised, "vie in beauty and variety of colouring with any other group in the invertebrate series"; yet Dr. McIntosh (6. See his beautiful monograph on 'British Annelids,' part i. 1873, p. 3.) cannot discover that these colours are of any service. The sedentary annelids become duller-coloured, according to M. Quatrefages (7. See M. Perrier: 'L'Origine de l'Homme d'après Darwin,' 'Revue Scientifique', Feb. 1873, p. 866.), after the period of reproduction; and this I presume may be attributed to their less vigorous condition at that time. All these worm-like animals apparently stand too low in the scale for the individuals of either sex to exert any choice in selecting a partner, or for the individuals of the same sex to struggle together in rivalry. SUB-KINGDOM OF THE ARTHROPODA: CLASS, CRUSTACEA. In this great class we first meet with undoubted secondary sexual characters, often developed in a remarkable manner. Unfortunately the habits of crustaceans are very imperfectly known, and we cannot explain the uses of many structures peculiar to one sex. With the lower parasitic species the males are of small size, and they alone are furnished with perfect swimming-legs, antennae and sense-organs; the females being destitute of these organs, with their bodies often consisting of a mere distorted mass. But these extraordinary differences between the two sexes are no doubt related to their widely different habits of life, and consequently do not concern us. In various crustaceans, belonging to distinct families, the anterior antennae are furnished with peculiar thread-like bodies, which are believed to act as smelling-organs, and these are much more numerous in the males than in the females. As the males, without any unusual development of their olfactory organs, would almost certainly be able sooner or later to find the females, the increased number of the smelling-threads has probably been acquired through sexual selection, by the better provided males having been the more successful in finding partners and in producing offspring. Fritz Müller has described a remarkable dimorphic species of Tanais, in which the male is represented by two distinct forms, which never graduate into each other. In the one form the male is furnished with more numerous smelling-threads, and in the other form with more powerful and more elongated chelae or pincers, which serve to hold the female. Fritz Müller suggests that these differences between the two male forms of the same species may have originated in certain individuals having varied in the number of the smelling-threads, whilst other individuals varied in the shape and size of their chelae; so that of the former, those which were best able to find the female, and of the latter, those which were best able to hold her, have left the greatest number of progeny to inherit their respective advantages. (8. 'Facts and Arguments for Darwin,' English translat., 1869, p. 20. See the previous discussion on the olfactory threads. Sars has described a somewhat analogous case (as quoted in 'Nature,' 1870, p. 455) in a Norwegian crustacean, the Pontoporeia affinis.) [Fig.4. Labidocera Darwinii (from Lubbock). Labelled are: a. Part of right anterior antenna of male, forming a prehensile organ. b. Posterior pair of thoracic legs of male. c. Ditto of female.] In some of the lower crustaceans, the right anterior antenna of the male differs greatly in structure from the left, the latter resembling in its simple tapering joints the antennae of the female. In the male the modified antenna is either swollen in the middle or angularly bent, or converted (Fig. 4) into an elegant, and sometimes wonderfully complex, prehensile organ. (9. See Sir J. Lubbock in 'Annals and Mag. of Nat. Hist.' vol. xi. 1853, pl. i. and x.; and vol. xii. (1853), pl. vii. See also Lubbock in 'Transactions, Entomological Society,' vol. iv. new series, 1856-1858, p. 8. With respect to the zigzagged antennae mentioned below, see Fritz Müller, 'Facts and Arguments for Darwin,' 1869, p. 40, foot-note.) It serves, as I hear from Sir J. Lubbock, to hold the female, and for this same purpose one of the two posterior legs (b) on the same side of the body is converted into a forceps. In another family the inferior or posterior antennae are "curiously zigzagged" in the males alone. [Fig. 5. Anterior part of body of Callianassa (from Milne-Edwards), showing the unequal and differently-constructed right and left-hand chelae of the male. N.B.--The artist by mistake has reversed the drawing, and made the left-hand chela the largest. Fig. 6. Second leg of male Orchestia Tucuratinga (from Fritz Müller). Fig. 7. Ditto of female.] In the higher crustaceans the anterior legs are developed into chelae or pincers; and these are generally larger in the male than in the female,--so much so that the market value of the male edible crab (Cancer pagurus), according to Mr. C. Spence Bate, is five times as great as that of the female. In many species the chelae are of unequal size on the opposite side of the body, the right-hand one being, as I am informed by Mr. Bate, generally, though not invariably, the largest. This inequality is also often much greater in the male than in the female. The two chelae of the male often differ in structure (Figs. 5, 6, and 7), the smaller one resembling that of the female. What advantage is gained by their inequality in size on the opposite sides of the body, and by the inequality being much greater in the male than in the female; and why, when they are of equal size, both are often much larger in the male than in the female, is not known. As I hear from Mr. Bate, the chelae are sometimes of such length and size that they cannot possibly be used for carrying food to the mouth. In the males of certain fresh-water prawns (Palaemon) the right leg is actually longer than the whole body. (10. See a paper by Mr. C. Spence Bate, with figures, in 'Proceedings, Zoological Society,' 1868, p. 363; and on the nomenclature of the genus, ibid. p. 585. I am greatly indebted to Mr. Spence Bate for nearly all the above statements with respect to the chelae of the higher crustaceans.) The great size of the one leg with its chelae may aid the male in fighting with his rivals; but this will not account for their inequality in the female on the opposite sides of the body. In Gelasimus, according to a statement quoted by Milne Edwards (11. 'Hist. Nat. des Crust.' tom. ii. 1837, p. 50.), the male and the female live in the same burrow, and this shews that they pair; the male closes the mouth of the burrow with one of its chelae, which is enormously developed; so that here it indirectly serves as a means of defence. Their main use, however, is probably to seize and to secure the female, and this in some instances, as with Gammarus, is known to be the case. The male of the hermit or soldier crab (Pagurus) for weeks together, carries about the shell inhabited by the female. (12. Mr. C. Spence Bate, 'British Association, Fourth Report on the Fauna of S. Devon.') The sexes, however, of the common shore-crab (Carcinus maenas), as Mr. Bate informs me, unite directly after the female has moulted her hard shell, when she is so soft that she would be injured if seized by the strong pincers of the male; but as she is caught and carried about by the male before moulting, she could then be seized with impunity. [Fig.8. Orchestia Darwinii (from Fritz Müller), showing the differently-constructed chelae of the two male forms.] Fritz Müller states that certain species of Melita are distinguished from all other amphipods by the females having "the coxal lamellae of the penultimate pair of feet produced into hook-like processes, of which the males lay hold with the hands of the first pair." The development of these hook-like processes has probably followed from those females which were the most securely held during the act of reproduction, having left the largest number of offspring. Another Brazilian amphipod (see Orchestia darwinii, Fig. 8) presents a case of dimorphism, like that of Tanais; for there are two male forms, which differ in the structure of their chelae. (13. Fritz Müller, 'Facts and Arguments for Darwin,' 1869, pp. 25-28.) As either chela would certainly suffice to hold the female,--for both are now used for this purpose,--the two male forms probably originated by some having varied in one manner and some in another; both forms having derived certain special, but nearly equal advantages, from their differently shaped organs. It is not known that male crustaceans fight together for the possession of the females, but it is probably the case; for with most animals when the male is larger than the female, he seems to owe his greater size to his ancestors having fought with other males during many generations. In most of the orders, especially in the highest or the Brachyura, the male is larger than the female; the parasitic genera, however, in which the sexes follow different habits of life, and most of the Entomostraca must be excepted. The chelae of many crustaceans are weapons well adapted for fighting. Thus when a Devil-crab (Portunus puber) was seen by a son of Mr. Bate fighting with a Carcinus maenas, the latter was soon thrown on its back, and had every limb torn from its body. When several males of a Brazilian Gelasimus, a species furnished with immense pincers, were placed together in a glass vessel by Fritz Müller, they mutilated and killed one another. Mr. Bate put a large male Carcinus maenas into a pan of water, inhabited by a female which was paired with a smaller male; but the latter was soon dispossessed. Mr. Bate adds, "if they fought, the victory was a bloodless one, for I saw no wounds." This same naturalist separated a male sand-skipper (so common on our sea-shores), Gammarus marinus, from its female, both of whom were imprisoned in the same vessel with many individuals of the same species. The female, when thus divorced, soon joined the others. After a time the male was put again into the same vessel; and he then, after swimming about for a time, dashed into the crowd, and without any fighting at once took away his wife. This fact shews that in the Amphipoda, an order low in the scale, the males and females recognise each other, and are mutually attached. The mental powers of the Crustacea are probably higher than at first sight appears probable. Any one who tries to catch one of the shore-crabs, so common on tropical coasts, will perceive how wary and alert they are. There is a large crab (Birgus latro), found on coral islands, which makes a thick bed of the picked fibres of the cocoa-nut, at the bottom of a deep burrow. It feeds on the fallen fruit of this tree by tearing off the husk, fibre by fibre; and it always begins at that end where the three eye-like depressions are situated. It then breaks through one of these eyes by hammering with its heavy front pincers, and turning round, extracts the albuminous core with its narrow posterior pincers. But these actions are probably instinctive, so that they would be performed as well by a young animal as by an old one. The following case, however, can hardly be so considered: a trustworthy naturalist, Mr. Gardner (14. 'Travels in the Interior of Brazil,' 1846, p. 111. I have given, in my 'Journal of Researches,' p. 463, an account of the habits of the Birgus.), whilst watching a shore-crab (Gelasimus) making its burrow, threw some shells towards the hole. One rolled in, and three other shells remained within a few inches of the mouth. In about five minutes the crab brought out the shell which had fallen in, and carried it away to a distance of a foot; it then saw the three other shells lying near, and evidently thinking that they might likewise roll in, carried them to the spot where it had laid the first. It would, I think, be difficult to distinguish this act from one performed by man by the aid of reason. Mr. Bate does not know of any well-marked case of difference of colour in the two sexes of our British crustaceans, in which respect the sexes of the higher animals so often differ. In some cases, however, the males and females differ slightly in tint, but Mr. Bate thinks not more than may be accounted for by their different habits of life, such as by the male wandering more about, and being thus more exposed to the light. Dr. Power tried to distinguish by colour the sexes of the several species which inhabit the Mauritius, but failed, except with one species of Squilla, probably S. stylifera, the male of which is described as being "of a beautiful bluish-green," with some of the appendages cherry-red, whilst the female is clouded with brown and grey, "with the red about her much less vivid than in the male." (15. Mr. Ch. Fraser, in 'Proc. Zoolog. Soc.' 1869, p. 3. I am indebted to Mr. Bate for Dr. Power's statement.) In this case, we may suspect the agency of sexual selection. From M. Bert's observations on Daphnia, when placed in a vessel illuminated by a prism, we have reason to believe that even the lowest crustaceans can distinguish colours. With Saphirina (an oceanic genus of Entomostraca), the males are furnished with minute shields or cell-like bodies, which exhibit beautiful changing colours; these are absent in the females, and in both sexes of one species. (16. Claus, 'Die freilebenden Copepoden,' 1863, s. 35.) It would, however, be extremely rash to conclude that these curious organs serve to attract the females. I am informed by Fritz Müller, that in the female of a Brazilian species of Gelasimus, the whole body is of a nearly uniform greyish-brown. In the male the posterior part of the cephalo-thorax is pure white, with the anterior part of a rich green, shading into dark brown; and it is remarkable that these colours are liable to change in the course of a few minutes--the white becoming dirty grey or even black, the green "losing much of its brilliancy." It deserves especial notice that the males do not acquire their bright colours until they become mature. They appear to be much more numerous than the females; they differ also in the larger size of their chelae. In some species of the genus, probably in all, the sexes pair and inhabit the same burrow. They are also, as we have seen, highly intelligent animals. From these various considerations it seems probable that the male in this species has become gaily ornamented in order to attract or excite the female. It has just been stated that the male Gelasimus does not acquire his conspicuous colours until mature and nearly ready to breed. This seems a general rule in the whole class in respect to the many remarkable structural differences between the sexes. We shall hereafter find the same law prevailing throughout the great sub-kingdom of the Vertebrata; and in all cases it is eminently distinctive of characters which have been acquired through sexual selection. Fritz Müller (17. 'Facts and Arguments,' etc., p. 79.) gives some striking instances of this law; thus the male sand-hopper (Orchestia) does not, until nearly full grown, acquire his large claspers, which are very differently constructed from those of the female; whilst young, his claspers resemble those of the female. CLASS, ARACHNIDA (SPIDERS). The sexes do not generally differ much in colour, but the males are often darker than the females, as may be seen in Mr. Blackwall's magnificent work. (18. 'A History of the Spiders of Great Britain,' 1861-64. For the following facts, see pp. 77, 88, 102.) In some species, however, the difference is conspicuous: thus the female of Sparassus smaragdulus is dullish green, whilst the adult male has the abdomen of a fine yellow, with three longitudinal stripes of rich red. In certain species of Thomisus the sexes closely resemble each other, in others they differ much; and analogous cases occur in many other genera. It is often difficult to say which of the two sexes departs most from the ordinary coloration of the genus to which the species belong; but Mr. Blackwall thinks that, as a general rule, it is the male; and Canestrini (19. This author has recently published a valuable essay on the 'Caratteri sessuali secondarii degli Arachnidi,' in the 'Atti della Soc. Veneto-Trentina di Sc. Nat. Padova,' vol. i. Fasc. 3, 1873.) remarks that in certain genera the males can be specifically distinguished with ease, but the females with great difficulty. I am informed by Mr. Blackwall that the sexes whilst young usually resemble each other; and both often undergo great changes in colour during their successive moults, before arriving at maturity. In other cases the male alone appears to change colour. Thus the male of the above bright-coloured Sparassus at first resembles the female, and acquires his peculiar tints only when nearly adult. Spiders are possessed of acute senses, and exhibit much intelligence; as is well known, the females often shew the strongest affection for their eggs, which they carry about enveloped in a silken web. The males search eagerly for the females, and have been seen by Canestrini and others to fight for possession of them. This same author says that the union of the two sexes has been observed in about twenty species; and he asserts positively that the female rejects some of the males who court her, threatens them with open mandibles, and at last after long hesitation accepts the chosen one. From these several considerations, we may admit with some confidence that the well-marked differences in colour between the sexes of certain species are the results of sexual selection; though we have not here the best kind of evidence,--the display by the male of his ornaments. From the extreme variability of colour in the male of some species, for instance of Theridion lineatum, it would appear that these sexual characters of the males have not as yet become well fixed. Canestrini draws the same conclusion from the fact that the males of certain species present two forms, differing from each other in the size and length of their jaws; and this reminds us of the above cases of dimorphic crustaceans. The male is generally much smaller than the female, sometimes to an extraordinary degree (20. Aug. Vinson ('Araneides des Iles de la Reunion,' pl. vi. figs. 1 and 2) gives a good instance of the small size of the male, in Epeira nigra. In this species, as I may add, the male is testaceous and the female black with legs banded with red. Other even more striking cases of inequality in size between the sexes have been recorded ('Quarterly Journal of Science,' July 1868, p. 429); but I have not seen the original accounts.), and he is forced to be extremely cautious in making his advances, as the female often carries her coyness to a dangerous pitch. De Geer saw a male that "in the midst of his preparatory caresses was seized by the object of his attentions, enveloped by her in a web and then devoured, a sight which, as he adds, filled him with horror and indignation." (21. Kirby and Spence, 'Introduction to Entomology,' vol. i. 1818, p. 280.) The Rev. O.P. Cambridge (22. 'Proceedings, Zoological Society,' 1871, p. 621.) accounts in the following manner for the extreme smallness of the male in the genus Nephila. "M. Vinson gives a graphic account of the agile way in which the diminutive male escapes from the ferocity of the female, by gliding about and playing hide and seek over her body and along her gigantic limbs: in such a pursuit it is evident that the chances of escape would be in favour of the smallest males, while the larger ones would fall early victims; thus gradually a diminutive race of males would be selected, until at last they would dwindle to the smallest possible size compatible with the exercise of their generative functions,--in fact, probably to the size we now see them, i.e., so small as to be a sort of parasite upon the female, and either beneath her notice, or too agile and too small for her to catch without great difficulty." Westring has made the interesting discovery that the males of several species of Theridion (23. Theridion (Asagena, Sund.) serratipes, 4-punctatum et guttatum; see Westring, in Kroyer, 'Naturhist. Tidskrift,' vol. iv. 1842-1843, p. 349; and vol. ii. 1846-1849, p. 342. See, also, for other species, 'Araneae Suecicae,' p. 184.) have the power of making a stridulating sound, whilst the females are mute. The apparatus consists of a serrated ridge at the base of the abdomen, against which the hard hinder part of the thorax is rubbed; and of this structure not a trace can be detected in the females. It deserves notice that several writers, including the well-known arachnologist Walckenaer, have declared that spiders are attracted by music. (24. Dr. H.H. van Zouteveen, in his Dutch translation of this work (vol. i. p. 444), has collected several cases.) From the analogy of the Orthoptera and Homoptera, to be described in the next chapter, we may feel almost sure that the stridulation serves, as Westring also believes, to call or to excite the female; and this is the first case known to me in the ascending scale of the animal kingdom of sounds emitted for this purpose. (25. Hilgendorf, however, has lately called attention to an analogous structure in some of the higher crustaceans, which seems adapted to produce sound; see 'Zoological Record,' 1869, p. 603.) CLASS, MYRIAPODA. In neither of the two orders in this class, the millipedes and centipedes, can I find any well-marked instances of such sexual differences as more particularly concern us. In Glomeris limbata, however, and perhaps in some few other species, the males differ slightly in colour from the females; but this Glomeris is a highly variable species. In the males of the Diplopoda, the legs belonging either to one of the anterior or of the posterior segments of the body are modified into prehensile hooks which serve to secure the female. In some species of Iulus the tarsi of the male are furnished with membranous suckers for the same purpose. As we shall see when we treat of Insects, it is a much more unusual circumstance, that it is the female in Lithobius, which is furnished with prehensile appendages at the extremity of her body for holding the male. (26. Walckenaer et P. Gervais, 'Hist. Nat. des Insectes: Apteres,' tom. iv. 1847, pp. 17, 19, 68.) CHAPTER X. SECONDARY SEXUAL CHARACTERS OF INSECTS. Diversified structures possessed by the males for seizing the females--Differences between the sexes, of which the meaning is not understood--Difference in size between the sexes--Thysanura--Diptera--Hemiptera--Homoptera, musical powers possessed by the males alone--Orthoptera, musical instruments of the males, much diversified in structure; pugnacity; colours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity and odours--Coleoptera, colours; furnished with great horns, apparently as an ornament; battles, stridulating organs generally common to both sexes. In the immense class of insects the sexes sometimes differ in their locomotive-organs, and often in their sense-organs, as in the pectinated and beautifully plumose antennae of the males of many species. In Chloeon, one of the Ephemerae, the male has great pillared eyes, of which the female is entirely destitute. (1. Sir J. Lubbock, 'Transact. Linnean Soc.' vol. xxv, 1866, p. 484. With respect to the Mutillidae see Westwood, 'Modern Class. of Insects,' vol. ii. p. 213.) The ocelli are absent in the females of certain insects, as in the Mutillidae; and here the females are likewise wingless. But we are chiefly concerned with structures by which one male is enabled to conquer another, either in battle or courtship, through his strength, pugnacity, ornaments, or music. The innumerable contrivances, therefore, by which the male is able to seize the female, may be briefly passed over. Besides the complex structures at the apex of the abdomen, which ought perhaps to be ranked as primary organs (2. These organs in the male often differ in closely-allied species, and afford excellent specific characters. But their importance, from a functional point of view, as Mr. R. MacLachlan has remarked to me, has probably been overrated. It has been suggested, that slight differences in these organs would suffice to prevent the intercrossing of well-marked varieties or incipient species, and would thus aid in their development. That this can hardly be the case, we may infer from the many recorded cases (see, for instance, Bronn, 'Geschichte der Natur,' B. ii. 1843, s. 164; and Westwood, 'Transact. Ent. Soc.' vol. iii. 1842, p. 195) of distinct species having been observed in union. Mr. MacLachlan informs me (vide 'Stett. Ent. Zeitung,' 1867, s. 155) that when several species of Phryganidae, which present strongly-pronounced differences of this kind, were confined together by Dr. Aug. Meyer, THEY COUPLED, and one pair produced fertile ova.), "it is astonishing," as Mr. B.D. Walsh (3. 'The Practical Entomologist,' Philadelphia, vol. ii. May 1867, p. 88.) has remarked, "how many different organs are worked in by nature for the seemingly insignificant object of enabling the male to grasp the female firmly." The mandibles or jaws are sometimes used for this purpose; thus the male Corydalis cornutus (a neuropterous insect in some degree allied to the Dragon flies, etc.) has immense curved jaws, many times longer than those of the female; and they are smooth instead of being toothed, so that he is thus enabled to seize her without injury. (4. Mr. Walsh, ibid. p. 107.) One of the stag-beetles of North America (Lucanus elaphus) uses his jaws, which are much larger than those of the female, for the same purpose, but probably likewise for fighting. In one of the sand-wasps (Ammophila) the jaws in the two sexes are closely alike, but are used for widely different purposes: the males, as Professor Westwood observes, "are exceedingly ardent, seizing their partners round the neck with their sickle-shaped jaws" (5. 'Modern Classification of Insects,' vol. ii. 1840, pp. 205, 206. Mr. Walsh, who called my attention to the double use of the jaws, says that he has repeatedly observed this fact.); whilst the females use these organs for burrowing in sand-banks and making their nests. [Fig. 9. Crabro cribrarius. Upper figure, male; lower figure, female.] The tarsi of the front-legs are dilated in many male beetles, or are furnished with broad cushions of hairs; and in many genera of water-beetles they are armed with a round flat sucker, so that the male may adhere to the slippery body of the female. It is a much more unusual circumstance that the females of some water-beetles (Dytiscus) have their elytra deeply grooved, and in Acilius sulcatus thickly set with hairs, as an aid to the male. The females of some other water-beetles (Hydroporus) have their elytra punctured for the same purpose. (6. We have here a curious and inexplicable case of dimorphism, for some of the females of four European species of Dytiscus, and of certain species of Hydroporus, have their elytra smooth; and no intermediate gradations between the sulcated or punctured, and the quite smooth elytra have been observed. See Dr. H. Schaum, as quoted in the 'Zoologist,' vols. v.-vi. 1847-48, p. 1896. Also Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 305.) In the male of Crabro cribrarius (Fig. 9), it is the tibia which is dilated into a broad horny plate, with minute membraneous dots, giving to it a singular appearance like that of a riddle. (7. Westwood, 'Modern Class.' vol. ii. p. 193. The following statement about Penthe, and others in inverted commas, are taken from Mr. Walsh, 'Practical Entomologist,' Philadelphia, vol. iii. p. 88.) In the male of Penthe (a genus of beetles) a few of the middle joints of the antennae are dilated and furnished on the inferior surface with cushions of hair, exactly like those on the tarsi of the Carabidae, "and obviously for the same end." In male dragon-flies, "the appendages at the tip of the tail are modified in an almost infinite variety of curious patterns to enable them to embrace the neck of the female." Lastly, in the males of many insects, the legs are furnished with peculiar spines, knobs or spurs; or the whole leg is bowed or thickened, but this is by no means invariably a sexual character; or one pair, or all three pairs are elongated, sometimes to an extravagant length. (8. Kirby and Spence, 'Introduct.' etc., vol. iii. pp. 332-336.) [Fig. 10. Taphroderes distortus (much enlarged). Upper figure, male; lower figure, female.] The sexes of many species in all the orders present differences, of which the meaning is not understood. One curious case is that of a beetle (Fig. 10), the male of which has left mandible much enlarged; so that the mouth is greatly distorted. In another Carabidous beetle, Eurygnathus (9. 'Insecta Maderensia,' 1854, page 20.), we have the case, unique as far as known to Mr. Wollaston, of the head of the female being much broader and larger, though in a variable degree, than that of the male. Any number of such cases could be given. They abound in the Lepidoptera: one of the most extraordinary is that certain male butterflies have their fore-legs more or less atrophied, with the tibiae and tarsi reduced to mere rudimentary knobs. The wings, also, in the two sexes often differ in neuration (10. E. Doubleday, 'Annals and Mag. of Nat. Hist.' vol. i. 1848, p. 379. I may add that the wings in certain Hymenoptera (see Shuckard, 'Fossorial Hymenoptera,' 1837, pp. 39-43) differ in neuration according to sex.), and sometimes considerably in outline, as in the Aricoris epitus, which was shewn to me in the British Museum by Mr. A. Butler. The males of certain South American butterflies have tufts of hair on the margins of the wings, and horny excrescences on the discs of the posterior pair. (11. H.W. Bates, in 'Journal of Proc. Linn. Soc.' vol. vi. 1862, p. 74. Mr. Wonfor's observations are quoted in 'Popular Science Review,' 1868, p. 343.) In several British butterflies, as shewn by Mr. Wonfor, the males alone are in parts clothed with peculiar scales. The use of the bright light of the female glow-worm has been subject to much discussion. The male is feebly luminous, as are the larvae and even the eggs. It has been supposed by some authors that the light serves to frighten away enemies, and by others to guide the male to the female. At last, Mr. Belt (12. 'The Naturalist in Nicaragua,' 1874, pp. 316-320. On the phosphorescence of the eggs, see 'Annals and Magazine of Natural History,' Nov. 1871, p. 372.) appears to have solved the difficulty: he finds that all the Lampyridae which he has tried are highly distasteful to insectivorous mammals and birds. Hence it is in accordance with Mr. Bates' view, hereafter to be explained, that many insects mimic the Lampyridae closely, in order to be mistaken for them, and thus to escape destruction. He further believes that the luminous species profit by being at once recognised as unpalatable. It is probable that the same explanation may be extended to the Elaters, both sexes of which are highly luminous. It is not known why the wings of the female glow-worm have not been developed; but in her present state she closely resembles a larva, and as larvae are so largely preyed on by many animals, we can understand why she has been rendered so much more luminous and conspicuous than the male; and why the larvae themselves are likewise luminous. DIFFERENCE IN SIZE BETWEEN THE SEXES. With insects of all kinds the males are commonly smaller than the females; and this difference can often be detected even in the larval state. So considerable is the difference between the male and female cocoons of the silk-moth (Bombyx mori), that in France they are separated by a particular mode of weighing. (13. Robinet, 'Vers a Soie,' 1848, p. 207.) In the lower classes of the animal kingdom, the greater size of the females seems generally to depend on their developing an enormous number of ova; and this may to a certain extent hold good with insects. But Dr. Wallace has suggested a much more probable explanation. He finds, after carefully attending to the development of the caterpillars of Bombyx cynthia and yamamai, and especially to that of some dwarfed caterpillars reared from a second brood on unnatural food, "that in proportion as the individual moth is finer, so is the time required for its metamorphosis longer; and for this reason the female, which is the larger and heavier insect, from having to carry her numerous eggs, will be preceded by the male, which is smaller and has less to mature." (14. 'Transact. Ent. Soc.' 3rd series, vol. v. p. 486.) Now as most insects are short-lived, and as they are exposed to many dangers, it would manifestly be advantageous to the female to be impregnated as soon as possible. This end would be gained by the males being first matured in large numbers ready for the advent of the females; and this again would naturally follow, as Mr. A.R. Wallace has remarked (15. 'Journal of Proc. Ent. Soc.' Feb. 4, 1867, p. lxxi.), through natural selection; for the smaller males would be first matured, and thus would procreate a large number of offspring which would inherit the reduced size of their male parents, whilst the larger males from being matured later would leave fewer offspring. There are, however, exceptions to the rule of male insects being smaller than the females: and some of these exceptions are intelligible. Size and strength would be an advantage to the males, which fight for the possession of the females; and in these cases, as with the stag-beetle (Lucanus), the males are larger than the females. There are, however, other beetles which are not known to fight together, of which the males exceed the females in size; and the meaning of this fact is not known; but in some of these cases, as with the huge Dynastes and Megasoma, we can at least see that there would be no necessity for the males to be smaller than the females, in order to be matured before them, for these beetles are not short-lived, and there would be ample time for the pairing of the sexes. So again, male dragon-flies (Libellulidae) are sometimes sensibly larger, and never smaller, than the females (16. For this and other statements on the size of the sexes, see Kirby and Spence, ibid. vol. iii. p. 300; on the duration of life in insects, see p. 344.); and as Mr. MacLachlan believes, they do not generally pair with the females until a week or fortnight has elapsed, and until they have assumed their proper masculine colours. But the most curious case, shewing on what complex and easily-overlooked relations, so trifling a character as difference in size between the sexes may depend, is that of the aculeate Hymenoptera; for Mr. F. Smith informs me that throughout nearly the whole of this large group, the males, in accordance with the general rule, are smaller than the females, and emerge about a week before them; but amongst the Bees, the males of Apis mellifica, Anthidium manicatum, and Anthophora acervorum, and amongst the Fossores, the males of the Methoca ichneumonides, are larger than the females. The explanation of this anomaly is that a marriage flight is absolutely necessary with these species, and the male requires great strength and size in order to carry the female through the air. Increased size has here been acquired in opposition to the usual relation between size and the period of development, for the males, though larger, emerge before the smaller females. We will now review the several Orders, selecting such facts as more particularly concern us. The Lepidoptera (Butterflies and Moths) will be retained for a separate chapter. ORDER, THYSANURA. The members of this lowly organised order are wingless, dull-coloured, minute insects, with ugly, almost misshapen heads and bodies. Their sexes do not differ, but they are interesting as shewing us that the males pay sedulous court to the females even low down in the animal scale. Sir J. Lubbock (17. 'Transact. Linnean Soc.' vol. xxvi. 1868, p. 296.) says: "it is very amusing to see these little creatures (Smynthurus luteus) coquetting together. The male, which is much smaller than the female, runs round her, and they butt one another, standing face to face and moving backward and forward like two playful lambs. Then the female pretends to run away and the male runs after her with a queer appearance of anger, gets in front and stands facing her again; then she turns coyly round, but he, quicker and more active, scuttles round too, and seems to whip her with his antennae; then for a bit they stand face to face, play with their antennae, and seem to be all in all to one another." ORDER, DIPTERA (FLIES). The sexes differ little in colour. The greatest difference, known to Mr. F. Walker, is in the genus Bibio, in which the males are blackish or quite black, and the females obscure brownish-orange. The genus Elaphomyia, discovered by Mr. Wallace (18. 'The Malay Archipelago,' vol. ii. 1869, p. 313.) in New Guinea, is highly remarkable, as the males are furnished with horns, of which the females are quite destitute. The horns spring from beneath the eyes, and curiously resemble those of a stag, being either branched or palmated. In one of the species, they equal the whole body in length. They might be thought to be adapted for fighting, but as in one species they are of a beautiful pink colour, edged with black, with a pale central stripe, and as these insects have altogether a very elegant appearance, it is perhaps more probable that they serve as ornaments. That the males of some Diptera fight together is certain; Prof. Westwood (19. 'Modern Classification of Insects,' vol. ii. 1840, p. 526.) has several times seen this with the Tipulae. The males of other Diptera apparently try to win the females by their music: H. Müller (20. 'Anwendung,' etc., 'Verh. d. n. V. Jahrg.' xxix. p. 80. Mayer, in 'American Naturalist,' 1874, p. 236.) watched for some time two males of an Eristalis courting a female; they hovered above her, and flew from side to side, making a high humming noise at the same time. Gnats and mosquitoes (Culicidae) also seem to attract each other by humming; and Prof. Mayer has recently ascertained that the hairs on the antennae of the male vibrate in unison with the notes of a tuning-fork, within the range of the sounds emitted by the female. The longer hairs vibrate sympathetically with the graver notes, and the shorter hairs with the higher ones. Landois also asserts that he has repeatedly drawn down a whole swarm of gnats by uttering a particular note. It may be added that the mental faculties of the Diptera are probably higher than in most other insects, in accordance with their highly-developed nervous system. (21. See Mr. B.T. Lowne's interesting work, 'On the Anatomy of the Blow-fly, Musca vomitoria,' 1870, p. 14. He remarks (p. 33) that, "the captured flies utter a peculiar plaintive note, and that this sound causes other flies to disappear.") ORDER, HEMIPTERA (FIELD-BUGS). Mr. J.W. Douglas, who has particularly attended to the British species, has kindly given me an account of their sexual differences. The males of some species are furnished with wings, whilst the females are wingless; the sexes differ in the form of their bodies, elytra, antennae and tarsi; but as the signification of these differences are unknown, they may be here passed over. The females are generally larger and more robust than the males. With British, and, as far as Mr. Douglas knows, with exotic species, the sexes do not commonly differ much in colour; but in about six British species the male is considerably darker than the female, and in about four other species the female is darker than the male. Both sexes of some species are beautifully coloured; and as these insects emit an extremely nauseous odour, their conspicuous colours may serve as a signal that they are unpalatable to insectivorous animals. In some few cases their colours appear to be directly protective: thus Prof. Hoffmann informs me that he could hardly distinguish a small pink and green species from the buds on the trunks of lime-trees, which this insect frequents. Some species of Reduvidae make a stridulating noise; and, in the case of Pirates stridulus, this is said (22. Westwood, 'Modern Classification of Insects,' vol. ii. p. 473.) to be effected by the movement of the neck within the pro-thoracic cavity. According to Westring, Reduvius personatus also stridulates. But I have no reason to suppose that this is a sexual character, excepting that with non-social insects there seems to be no use for sound-producing organs, unless it be as a sexual call. ORDER: HOMOPTERA. Every one who has wandered in a tropical forest must have been astonished at the din made by the male Cicadae. The females are mute; as the Grecian poet Xenarchus says, "Happy the Cicadas live, since they all have voiceless wives." The noise thus made could be plainly heard on board the "Beagle," when anchored at a quarter of a mile from the shore of Brazil; and Captain Hancock says it can be heard at the distance of a mile. The Greeks formerly kept, and the Chinese now keep these insects in cages for the sake of their song, so that it must be pleasing to the ears of some men. (23. These particulars are taken from Westwood's 'Modern Classification of Insects,' vol. ii. 1840, p. 422. See, also, on the Fulgoridae, Kirby and Spence, 'Introduct.' vol. ii. p. 401.) The Cicadidae usually sing during the day, whilst the Fulgoridae appear to be night-songsters. The sound, according to Landois (24. 'Zeitschrift für wissenschaft. Zoolog.' B. xvii. 1867, ss. 152-158.), is produced by the vibration of the lips of the spiracles, which are set into motion by a current of air emitted from the tracheae; but this view has lately been disputed. Dr. Powell appears to have proved (25. 'Transactions of the New Zealand Institute,' vol. v. 1873, p. 286.) that it is produced by the vibration of a membrane, set into action by a special muscle. In the living insect, whilst stridulating, this membrane can be seen to vibrate; and in the dead insect the proper sound is heard, if the muscle, when a little dried and hardened, is pulled with the point of a pin. In the female the whole complex musical apparatus is present, but is much less developed than in the male, and is never used for producing sound. With respect to the object of the music, Dr. Hartman, in speaking of the Cicada septemdecim of the United States, says (26. I am indebted to Mr. Walsh for having sent me this extract from 'A Journal of the Doings of Cicada septemdecim,' by Dr. Hartman.), "the drums are now (June 6th and 7th, 1851) heard in all directions. This I believe to be the marital summons from the males. Standing in thick chestnut sprouts about as high as my head, where hundreds were around me, I observed the females coming around the drumming males." He adds, "this season (Aug. 1868) a dwarf pear-tree in my garden produced about fifty larvae of Cic. pruinosa; and I several times noticed the females to alight near a male while he was uttering his clanging notes." Fritz Müller writes to me from S. Brazil that he has often listened to a musical contest between two or three males of a species with a particularly loud voice, seated at a considerable distance from each other: as soon as one had finished his song, another immediately began, and then another. As there is so much rivalry between the males, it is probable that the females not only find them by their sounds, but that, like female birds, they are excited or allured by the male with the most attractive voice. I have not heard of any well-marked cases of ornamental differences between the sexes of the Homoptera. Mr. Douglas informs me that there are three British species, in which the male is black or marked with black bands, whilst the females are pale-coloured or obscure. ORDER, ORTHOPTERA (CRICKETS AND GRASSHOPPERS). The males in the three saltatorial families in this Order are remarkable for their musical powers, namely the Achetidae or crickets, the Locustidae for which there is no equivalent English name, and the Acridiidae or grasshoppers. The stridulation produced by some of the Locustidae is so loud that it can be heard during the night at the distance of a mile (27. L. Guilding, 'Transactions of the Linnean Society,' vol. xv. p. 154.); and that made by certain species is not unmusical even to the human ear, so that the Indians on the Amazons keep them in wicker cages. All observers agree that the sounds serve either to call or excite the mute females. With respect to the migratory locusts of Russia, Korte has given (28. I state this on the authority of Koppen, '�ber die Heuschrecken in Südrussland,' 1866, p. 32, for I have in vain endeavoured to procure Korte's work.) an interesting case of selection by the female of a male. The males of this species (Pachytylus migratorius) whilst coupled with the female stridulate from anger or jealousy, if approached by other males. The house-cricket when surprised at night uses its voice to warn its fellows. (29. Gilbert White, 'Natural History of Selborne,' vol. ii. 1825, p. 262.) In North America the Katy-did (Platyphyllum concavum, one of the Locustidae) is described (30. Harris, 'Insects of New England,' 1842, p. 128.) as mounting on the upper branches of a tree, and in the evening beginning "his noisy babble, while rival notes issue from the neighbouring trees, and the groves resound with the call of Katy-did-she-did the live-long night." Mr. Bates, in speaking of the European field-cricket (one of the Achetidae), says "the male has been observed to place himself in the evening at the entrance of his burrow, and stridulate until a female approaches, when the louder notes are succeeded by a more subdued tone, whilst the successful musician caresses with his antennae the mate he has won." (31. 'The Naturalist on the Amazons,' vol. i. 1863, p. 252. Mr. Bates gives a very interesting discussion on the gradations in the musical apparatus of the three families. See also Westwood, 'Modern Classification of Insects,' vol. ii. pp. 445 and 453.) Dr. Scudder was able to excite one of these insects to answer him, by rubbing on a file with a quill. (32. 'Proceedings of the Boston Society of Natural History,' vol. xi. April 1868.) In both sexes a remarkable auditory apparatus has been discovered by Von Siebold, situated in the front legs. (33. 'Nouveau Manuel d'Anat. Comp.' (French translat.), tom. 1, 1850, p. 567.) [Fig.11. Gryllus campestris (from Landois). Right-hand figure, under side of part of a wing-nervure, much magnified, showing the teeth, st. Left-hand figure, upper surface of wing-cover, with the projecting, smooth nervure, r, across which the teeth (st) are scraped. Fig.12. Teeth of Nervure of Gryllus domesticus (from Landois).] In the three Families the sounds are differently produced. In the males of the Achetidae both wing-covers have the same apparatus; and this in the field-cricket (see Gryllus campestris, Fig. 11) consists, as described by Landois (34. 'Zeitschrift für wissenschaft. Zoolog.' B. xvii. 1867, s. 117.), of from 131 to 138 sharp, transverse ridges or teeth (st) on the under side of one of the nervures of the wing-cover. This toothed nervure is rapidly scraped across a projecting, smooth, hard nervure (r) on the upper surface of the opposite wing. First one wing is rubbed over the other, and then the movement is reversed. Both wings are raised a little at the same time, so as to increase the resonance. In some species the wing-covers of the males are furnished at the base with a talc-like plate. (35. Westwood, 'Modern Classification of Insects,' vol. i. p. 440.) I here give a drawing (Fig. 12) of the teeth on the under side of the nervure of another species of Gryllus, viz., G. domesticus. With respect to the formation of these teeth, Dr. Gruber has shewn (36. 'Ueber der Tonapparat der Locustiden, ein Beitrag zum Darwinismus,' 'Zeitschrift für wissenschaft. Zoolog.' B. xxii. 1872, p. 100.) that they have been developed by the aid of selection, from the minute scales and hairs with which the wings and body are covered, and I came to the same conclusion with respect to those of the Coleoptera. But Dr. Gruber further shews that their development is in part directly due to the stimulus from the friction of one wing over the other. [Fig.13. Chlorocoelus Tanana (from Bates). a,b. Lobes of opposite wing-covers.] In the Locustidae the opposite wing-covers differ from each other in structure (Fig. 13), and the action cannot, as in the last family, be reversed. The left wing, which acts as the bow, lies over the right wing which serves as the fiddle. One of the nervures (a) on the under surface of the former is finely serrated, and is scraped across the prominent nervures on the upper surface of the opposite or right wing. In our British Phasgonura viridissima it appeared to me that the serrated nervure is rubbed against the rounded hind-corner of the opposite wing, the edge of which is thickened, coloured brown, and very sharp. In the right wing, but not in the left, there is a little plate, as transparent as talc, surrounded by nervures, and called the speculum. In Ephippiger vitium, a member of this same family, we have a curious subordinate modification; for the wing-covers are greatly reduced in size, but "the posterior part of the pro-thorax is elevated into a kind of dome over the wing-covers, and which has probably the effect of increasing the sound." (37. Westwood 'Modern Classification of Insects,' vol. i. p. 453.) We thus see that the musical apparatus is more differentiated or specialised in the Locustidae (which include, I believe, the most powerful performers in the Order), than in the Achetidae, in which both wing-covers have the same structure and the same function. (38. Landois, 'Zeitschrift für wissenschaft. Zoolog.' B. xvii. 1867, ss. 121, 122.) Landois, however, detected in one of the Locustidae, namely in Decticus, a short and narrow row of small teeth, mere rudiments, on the inferior surface of the right wing-cover, which underlies the other and is never used as the bow. I observed the same rudimentary structure on the under side of the right wing-cover in Phasgonura viridissima. Hence we may infer with confidence that the Locustidae are descended from a form, in which, as in the existing Achetidae, both wing-covers had serrated nervures on the under surface, and could be indifferently used as the bow; but that in the Locustidae the two wing-covers gradually became differentiated and perfected, on the principle of the division of labour, the one to act exclusively as the bow, and the other as the fiddle. Dr. Gruber takes the same view, and has shewn that rudimentary teeth are commonly found on the inferior surface of the right wing. By what steps the more simple apparatus in the Achetidae originated, we do not know, but it is probable that the basal portions of the wing-covers originally overlapped each other as they do at present; and that the friction of the nervures produced a grating sound, as is now the case with the wing-covers of the females. (39. Mr. Walsh also informs me that he has noticed that the female of the Platyphyllum concavum, "when captured makes a feeble grating noise by shuffling her wing-covers together.") A grating sound thus occasionally and accidentally made by the males, if it served them ever so little as a love-call to the females, might readily have been intensified through sexual selection, by variations in the roughness of the nervures having been continually preserved. [Fig.14. Hind-leg of Stenobothrus pratorum: r, the stridulating ridge; lower figure, the teeth forming the ridge, much magnified (from Landois). Fig.15. Pneumora (from specimens in the British Museum). Upper figure, male; lower figure, female.] In the last and third family, namely the Acridiidae or grasshoppers, the stridulation is produced in a very different manner, and according to Dr. Scudder, is not so shrill as in the preceding Families. The inner surface of the femur (Fig. 14, r) is furnished with a longitudinal row of minute, elegant, lancet-shaped, elastic teeth, from 85 to 93 in number (40. Landois, ibid. s. 113.); and these are scraped across the sharp, projecting nervures on the wing-covers, which are thus made to vibrate and resound. Harris (41. 'Insects of New England,' 1842, p. 133.) says that when one of the males begins to play, he first "bends the shank of the hind-leg beneath the thigh, where it is lodged in a furrow designed to receive it, and then draws the leg briskly up and down. He does not play both fiddles together, but alternately, first upon one and then on the other." In many species, the base of the abdomen is hollowed out into a great cavity which is believed to act as a resounding board. In Pneumora (Fig. 15), a S. African genus belonging to the same family, we meet with a new and remarkable modification; in the males a small notched ridge projects obliquely from each side of the abdomen, against which the hind femora are rubbed. (42. Westwood, 'Modern Classification,' vol i. p. 462.) As the male is furnished with wings (the female being wingless), it is remarkable that the thighs are not rubbed in the usual manner against the wing-covers; but this may perhaps be accounted for by the unusually small size of the hind-legs. I have not been able to examine the inner surface of the thighs, which, judging from analogy, would be finely serrated. The species of Pneumora have been more profoundly modified for the sake of stridulation than any other orthopterous insect; for in the male the whole body has been converted into a musical instrument, being distended with air, like a great pellucid bladder, so as to increase the resonance. Mr. Trimen informs me that at the Cape of Good Hope these insects make a wonderful noise during the night. In the three foregoing families, the females are almost always destitute of an efficient musical apparatus. But there are a few exceptions to this rule, for Dr. Gruber has shewn that both sexes of Ephippiger vitium are thus provided; though the organs differ in the male and female to a certain extent. Hence we cannot suppose that they have been transferred from the male to the female, as appears to have been the case with the secondary sexual characters of many other animals. They must have been independently developed in the two sexes, which no doubt mutually call to each other during the season of love. In most other Locustidae (but not according to Landois in Decticus) the females have rudiments of the stridulatory organs proper to the male; from whom it is probable that these have been transferred. Landois also found such rudiments on the under surface of the wing-covers of the female Achetidae, and on the femora of the female Acridiidae. In the Homoptera, also, the females have the proper musical apparatus in a functionless state; and we shall hereafter meet in other divisions of the animal kingdom with many instances of structures proper to the male being present in a rudimentary condition in the female. Landois has observed another important fact, namely, that in the females of the Acridiidae, the stridulating teeth on the femora remain throughout life in the same condition in which they first appear during the larval state in both sexes. In the males, on the other hand, they become further developed, and acquire their perfect structure at the last moult, when the insect is mature and ready to breed. From the facts now given, we see that the means by which the males of the Orthoptera produce their sounds are extremely diversified, and are altogether different from those employed by the Homoptera. (43. Landois has recently found in certain Orthoptera rudimentary structures closely similar to the sound-producing organs in the Homoptera; and this is a surprising fact. See 'Zeitschrift für wissenschaft, Zoolog.' B. xxii. Heft 3, 1871, p. 348.) But throughout the animal kingdom we often find the same object gained by the most diversified means; this seems due to the whole organisation having undergone multifarious changes in the course of ages, and as part after part varied different variations were taken advantage of for the same general purpose. The diversity of means for producing sound in the three families of the Orthoptera and in the Homoptera, impresses the mind with the high importance of these structures to the males, for the sake of calling or alluring the females. We need feel no surprise at the amount of modification which the Orthoptera have undergone in this respect, as we now know, from Dr. Scudder's remarkable discovery (44. 'Transactions, Entomological Society,' 3rd series, vol. ii. ('Journal of Proceedings,' p. 117).), that there has been more than ample time. This naturalist has lately found a fossil insect in the Devonian formation of New Brunswick, which is furnished with "the well-known tympanum or stridulating apparatus of the male Locustidae." The insect, though in most respects related to the Neuroptera, appears, as is so often the case with very ancient forms, to connect the two related Orders of the Neuroptera and Orthoptera. I have but little more to say on the Orthoptera. Some of the species are very pugnacious: when two male field-crickets (Gryllus campestris) are confined together, they fight till one kills the other; and the species of Mantis are described as manoeuvring with their sword-like front-limbs, like hussars with their sabres. The Chinese keep these insects in little bamboo cages, and match them like game-cocks. (45. Westwood, 'Modern Classification of Insects,' vol. i. p. 427; for crickets, p. 445.) With respect to colour, some exotic locusts are beautifully ornamented; the posterior wings being marked with red, blue, and black; but as throughout the Order the sexes rarely differ much in colour, it is not probable that they owe their bright tints to sexual selection. Conspicuous colours may be of use to these insects, by giving notice that they are unpalatable. Thus it has been observed (46. Mr. Ch. Horne, in 'Proceedings of the Entomological Society,' May 3, 1869, p. xii.) that a bright-coloured Indian locust was invariably rejected when offered to birds and lizards. Some cases, however, are known of sexual differences in colour in this Order. The male of an American cricket (47. The Oecanthus nivalis, Harris, 'Insects of New England,' 1842, p. 124. The two sexes of OE. pellucidus of Europe differ, as I hear from Victor Carus, in nearly the same manner.) is described as being as white as ivory, whilst the female varies from almost white to greenish-yellow or dusky. Mr. Walsh informs me that the adult male of Spectrum femoratum (one of the Phasmidae) "is of a shining brownish-yellow colour; the adult female being of a dull, opaque, cinereous brown; the young of both sexes being green." Lastly, I may mention that the male of one curious kind of cricket (48. Platyblemnus: Westwood, 'Modern Classification,' vol. i. p. 447.) is furnished with "a long membranous appendage, which falls over the face like a veil;" but what its use may be, is not known. ORDER, NEUROPTERA. Little need here be said, except as to colour. In the Ephemeridae the sexes often differ slightly in their obscure tints (49. B.D. Walsh, the 'Pseudo-neuroptera of Illinois,' in 'Proceedings of the Entomological Society of Philadelphia,' 1862, p. 361.); but it is not probable that the males are thus rendered attractive to the females. The Libellulidae, or dragon-flies, are ornamented with splendid green, blue, yellow, and vermilion metallic tints; and the sexes often differ. Thus, as Prof. Westwood remarks (50. 'Modern Classification,' vol. ii. p. 37.), the males of some of the Agrionidae, "are of a rich blue with black wings, whilst the females are fine green with colourless wings." But in Agrion Ramburii these colours are exactly reversed in the two sexes. (51. Walsh, ibid. p. 381. I am indebted to this naturalist for the following facts on Hetaerina, Anax, and Gomphus.) In the extensive N. American genus of Hetaerina, the males alone have a beautiful carmine spot at the base of each wing. In Anax junius the basal part of the abdomen in the male is a vivid ultramarine blue, and in the female grass-green. In the allied genus Gomphus, on the other hand, and in some other genera, the sexes differ but little in colour. In closely-allied forms throughout the animal kingdom, similar cases of the sexes differing greatly, or very little, or not at all, are of frequent occurrence. Although there is so wide a difference in colour between the sexes of many Libellulidae, it is often difficult to say which is the more brilliant; and the ordinary coloration of the two sexes is reversed, as we have just seen, in one species of Agrion. It is not probable that their colours in any case have been gained as a protection. Mr. MacLachlan, who has closely attended to this family, writes to me that dragon-flies--the tyrants of the insect-world--are the least liable of any insect to be attacked by birds or other enemies, and he believes that their bright colours serve as a sexual attraction. Certain dragon-flies apparently are attracted by particular colours: Mr. Patterson observed (52. 'Transactions, Ent. Soc.' vol. i. 1836, p. lxxxi.) that the Agrionidae, of which the males are blue, settled in numbers on the blue float of a fishing line; whilst two other species were attracted by shining white colours. It is an interesting fact, first noticed by Schelver, that, in several genera belonging to two sub-families, the males on first emergence from the pupal state, are coloured exactly like the females; but that their bodies in a short time assume a conspicuous milky-blue tint, owing to the exudation of a kind of oil, soluble in ether and alcohol. Mr. MacLachlan believes that in the male of Libellula depressa this change of colour does not occur until nearly a fortnight after the metamorphosis, when the sexes are ready to pair. Certain species of Neurothemis present, according to Brauer (53. See abstract in the 'Zoological Record' for 1867, p. 450.), a curious case of dimorphism, some of the females having ordinary wings, whilst others have them "very richly netted, as in the males of the same species." Brauer "explains the phenomenon on Darwinian principles by the supposition that the close netting of the veins is a secondary sexual character in the males, which has been abruptly transferred to some of the females, instead of, as generally occurs, to all of them." Mr. MacLachlan informs me of another instance of dimorphism in several species of Agrion, in which some individuals are of an orange colour, and these are invariably females. This is probably a case of reversion; for in the true Libellulae, when the sexes differ in colour, the females are orange or yellow; so that supposing Agrion to be descended from some primordial form which resembled the typical Libellulae in its sexual characters, it would not be surprising that a tendency to vary in this manner should occur in the females alone. Although many dragon-flies are large, powerful, and fierce insects, the males have not been observed by Mr. MacLachlan to fight together, excepting, as he believes, in some of the smaller species of Agrion. In another group in this Order, namely, the Termites or white ants, both sexes at the time of swarming may be seen running about, "the male after the female, sometimes two chasing one female, and contending with great eagerness who shall win the prize." (54. Kirby and Spence, 'Introduction to Entomology,' vol. ii. 1818, p. 35.) The Atropos pulsatorius is said to make a noise with its jaws, which is answered by other individuals. (55. Houzeau, 'Les Facultés Mentales,' etc. Tom. i. p. 104.) ORDER, HYMENOPTERA. That inimitable observer, M. Fabre (56. See an interesting article, 'The Writings of Fabre,' in 'Nat. Hist. Review,' April 1862, p. 122.), in describing the habits of Cerceris, a wasp-like insect, remarks that "fights frequently ensue between the males for the possession of some particular female, who sits an apparently unconcerned beholder of the struggle for supremacy, and when the victory is decided, quietly flies away in company with the conqueror." Westwood (57. 'Journal of Proceedings of Entomological Society,' Sept. 7, 1863, p. 169.) says that the males of one of the saw-flies (Tenthredinae) "have been found fighting together, with their mandibles locked." As M. Fabre speaks of the males of Cerceris striving to obtain a particular female, it may be well to bear in mind that insects belonging to this Order have the power of recognising each other after long intervals of time, and are deeply attached. For instance, Pierre Huber, whose accuracy no one doubts, separated some ants, and when, after an interval of four months, they met others which had formerly belonged to the same community, they recognised and caressed one another with their antennae. Had they been strangers they would have fought together. Again, when two communities engage in a battle, the ants on the same side sometimes attack each other in the general confusion, but they soon perceive their mistake, and the one ant soothes the other. (58. P. Huber, 'Recherches sur les Moeurs des Fourmis,' 1810, pp. 150, 165.) In this Order slight differences in colour, according to sex, are common, but conspicuous differences are rare except in the family of Bees; yet both sexes of certain groups are so brilliantly coloured--for instance in Chrysis, in which vermilion and metallic greens prevail--that we are tempted to attribute the result to sexual selection. In the Ichneumonidae, according to Mr. Walsh (59. 'Proceedings of the Entomological Society of Philadelphia,' 1866, pp. 238, 239.), the males are almost universally lighter-coloured than the females. On the other hand, in the Tenthredinidae the males are generally darker than the females. In the Siricidae the sexes frequently differ; thus the male of Sirex juvencus is banded with orange, whilst the female is dark purple; but it is difficult to say which sex is the more ornamented. In Tremex columbae the female is much brighter coloured than the male. I am informed by Mr. F. Smith, that the male ants of several species are black, the females being testaceous. In the family of Bees, especially in the solitary species, as I hear from the same entomologist, the sexes often differ in colour. The males are generally the brighter, and in Bombus as well as in Apathus, much more variable in colour than the females. In Anthophora retusa the male is of a rich fulvous-brown, whilst the female is quite black: so are the females of several species of Xylocopa, the males being bright yellow. On the other hand the females of some species, as of Andraena fulva, are much brighter coloured than the males. Such differences in colour can hardly be accounted for by the males being defenceless and thus requiring protection, whilst the females are well defended by their stings. H. Müller (60. 'Anwendung der Darwinschen Lehre auf Bienen,' Verh. d. n. V. Jahrg. xxix.), who has particularly attended to the habits of bees, attributes these differences in colour in chief part to sexual selection. That bees have a keen perception of colour is certain. He says that the males search eagerly and fight for the possession of the females; and he accounts through such contests for the mandibles of the males being in certain species larger than those of the females. In some cases the males are far more numerous than the females, either early in the season, or at all times and places, or locally; whereas the females in other cases are apparently in excess. In some species the more beautiful males appear to have been selected by the females; and in others the more beautiful females by the males. Consequently in certain genera (Müller, p. 42), the males of the several species differ much in appearance, whilst the females are almost indistinguishable; in other genera the reverse occurs. H. Müller believes (p. 82) that the colours gained by one sex through sexual selection have often been transferred in a variable degree to the other sex, just as the pollen-collecting apparatus of the female has often been transferred to the male, to whom it is absolutely useless. (61. M. Perrier in his article 'la Selection sexuelle d'après Darwin' ('Revue Scientifique,' Feb. 1873, p. 868), without apparently having reflected much on the subject, objects that as the males of social bees are known to be produced from unfertilised ova, they could not transmit new characters to their male offspring. This is an extraordinary objection. A female bee fertilised by a male, which presented some character facilitating the union of the sexes, or rendering him more attractive to the female, would lay eggs which would produce only females; but these young females would next year produce males; and will it be pretended that such males would not inherit the characters of their male grandfathers? To take a case with ordinary animals as nearly parallel as possible: if a female of any white quadruped or bird were crossed by a male of a black breed, and the male and female offspring were paired together, will it be pretended that the grandchildren would not inherit a tendency to blackness from their male grandfather? The acquirement of new characters by the sterile worker-bees is a much more difficult case, but I have endeavoured to shew in my 'Origin of Species,' how these sterile beings are subjected to the power of natural selection.) Mutilla Europaea makes a stridulating noise; and according to Goureau (62. Quoted by Westwood, 'Modern Classification of Insects,' vol. ii. p. 214.) both sexes have this power. He attributes the sound to the friction of the third and preceding abdominal segments, and I find that these surfaces are marked with very fine concentric ridges; but so is the projecting thoracic collar into which the head articulates, and this collar, when scratched with the point of a needle, emits the proper sound. It is rather surprising that both sexes should have the power of stridulating, as the male is winged and the female wingless. It is notorious that Bees express certain emotions, as of anger, by the tone of their humming; and according to H. Müller (p. 80), the males of some species make a peculiar singing noise whilst pursuing the females. ORDER, COLEOPTERA (BEETLES). Many beetles are coloured so as to resemble the surfaces which they habitually frequent, and they thus escape detection by their enemies. Other species, for instance diamond-beetles, are ornamented with splendid colours, which are often arranged in stripes, spots, crosses, and other elegant patterns. Such colours can hardly serve directly as a protection, except in the case of certain flower-feeding species; but they may serve as a warning or means of recognition, on the same principle as the phosphorescence of the glow-worm. As with beetles the colours of the two sexes are generally alike, we have no evidence that they have been gained through sexual selection; but this is at least possible, for they have been developed in one sex and then transferred to the other; and this view is even in some degree probable in those groups which possess other well-marked secondary sexual characters. Blind beetles, which cannot of course behold each other's beauty, never, as I hear from Mr. Waterhouse, jun., exhibit bright colours, though they often have polished coats; but the explanation of their obscurity may be that they generally inhabit caves and other obscure stations. Some Longicorns, especially certain Prionidae, offer an exception to the rule that the sexes of beetles do not differ in colour. Most of these insects are large and splendidly coloured. The males in the genus Pyrodes (63. Pyrodes pulcherrimus, in which the sexes differ conspicuously, has been described by Mr. Bates in 'Transact. Ent. Soc.' 1869, p. 50. I will specify the few other cases in which I have heard of a difference in colour between the sexes of beetles. Kirby and Spence ('Introduct. to Entomology,' vol. iii. p. 301) mention a Cantharis, Meloe, Rhagium, and the Leptura testacea; the male of the latter being testaceous, with a black thorax, and the female of a dull red all over. These two latter beetles belong to the family of Longicorns. Messrs. R. Trimen and Waterhouse, jun., inform me of two Lamellicorns, viz., a Peritrichia and Trichius, the male of the latter being more obscurely coloured than the female. In Tillus elongatus the male is black, and the female always, as it is believed, of a dark blue colour, with a red thorax. The male, also, of Orsodacna atra, as I hear from Mr. Walsh, is black, the female (the so-called O. ruficollis) having a rufous thorax.), which I saw in Mr. Bates's collection, are generally redder but rather duller than the females, the latter being coloured of a more or less splendid golden-green. On the other hand, in one species the male is golden-green, the female being richly tinted with red and purple. In the genus Esmeralda the sexes differ so greatly in colour that they have been ranked as distinct species; in one species both are of a beautiful shining green, but the male has a red thorax. On the whole, as far as I could judge, the females of those Prionidae, in which the sexes differ, are coloured more richly than the males, and this does not accord with the common rule in regard to colour, when acquired through sexual selection. [Fig.16. Chalcosoma atlas. Upper figure, male (reduced); lower figure, female (nat. size). Fig. 17. Copris isidis. Fig. 18. Phanaeus faunus. Fig. 19. Dipelicus cantori. Fig. 20. Onthophagus rangifer, enlarged. (In Figs. 17 to 20 the left-hand figures are males.)] A most remarkable distinction between the sexes of many beetles is presented by the great horns which rise from the head, thorax, and clypeus of the males; and in some few cases from the under surface of the body. These horns, in the great family of the Lamellicorns, resemble those of various quadrupeds, such as stags, rhinoceroses, etc., and are wonderful both from their size and diversified shapes. Instead of describing them, I have given figures of the males and females of some of the more remarkable forms. (Figs. 16 to 20.) The females generally exhibit rudiments of the horns in the form of small knobs or ridges; but some are destitute of even the slightest rudiment. On the other hand, the horns are nearly as well developed in the female as in the male Phanaeus lancifer; and only a little less well developed in the females of some other species of this genus and of Copris. I am informed by Mr. Bates that the horns do not differ in any manner corresponding with the more important characteristic differences between the several subdivisions of the family: thus within the same section of the genus Onthophagus, there are species which have a single horn, and others which have two. In almost all cases, the horns are remarkable from their excessive variability; so that a graduated series can be formed, from the most highly developed males to others so degenerate that they can barely be distinguished from the females. Mr. Walsh (64. 'Proceedings of the Entomological Society of Philadephia,' 1864, p. 228.) found that in Phanaeus carnifex the horns were thrice as long in some males as in others. Mr. Bates, after examining above a hundred males of Onthophagus rangifer (Fig. 20), thought that he had at last discovered a species in which the horns did not vary; but further research proved the contrary. The extraordinary size of the horns, and their widely different structure in closely-allied forms, indicate that they have been formed for some purpose; but their excessive variability in the males of the same species leads to the inference that this purpose cannot be of a definite nature. The horns do not shew marks of friction, as if used for any ordinary work. Some authors suppose (65. Kirby and Spence, 'Introduction to Entomology,' vol. iii. p. 300.) that as the males wander about much more than the females, they require horns as a defence against their enemies; but as the horns are often blunt, they do not seem well adapted for defence. The most obvious conjecture is that they are used by the males for fighting together; but the males have never been observed to fight; nor could Mr. Bates, after a careful examination of numerous species, find any sufficient evidence, in their mutilated or broken condition, of their having been thus used. If the males had been habitual fighters, the size of their bodies would probably have been increased through sexual selection, so as to have exceeded that of the females; but Mr. Bates, after comparing the two sexes in above a hundred species of the Copridae, did not find any marked difference in this respect amongst well-developed individuals. In Lethrus, moreover, a beetle belonging to the same great division of the Lamellicorns, the males are known to fight, but are not provided with horns, though their mandibles are much larger than those of the female. The conclusion that the horns have been acquired as ornaments is that which best agrees with the fact of their having been so immensely, yet not fixedly, developed,--as shewn by their extreme variability in the same species, and by their extreme diversity in closely-allied species. This view will at first appear extremely improbable; but we shall hereafter find with many animals standing much higher in the scale, namely fishes, amphibians, reptiles and birds, that various kinds of crests, knobs, horns and combs have been developed apparently for this sole purpose. [Fig.21. Onitis furcifer, male viewed from beneath. Fig.22. Onitis furcifer. Left-hand figure, male, viewed laterally. Right-hand figure, female. a. Rudiment of cephalic horn. b. Trace of thoracic horn or crest.] The males of Onitis furcifer (Fig. 21), and of some other species of the genus, are furnished with singular projections on their anterior femora, and with a great fork or pair of horns on the lower surface of the thorax. Judging from other insects, these may aid the male in clinging to the female. Although the males have not even a trace of a horn on the upper surface of the body, yet the females plainly exhibit a rudiment of a single horn on the head (Fig. 22, a), and of a crest (b) on the thorax. That the slight thoracic crest in the female is a rudiment of a projection proper to the male, though entirely absent in the male of this particular species, is clear: for the female of Bubas bison (a genus which comes next to Onitis) has a similar slight crest on the thorax, and the male bears a great projection in the same situation. So, again, there can hardly be a doubt that the little point (a) on the head of the female Onitis furcifer, as well as on the head of the females of two or three allied species, is a rudimentary representative of the cephalic horn, which is common to the males of so many Lamellicorn beetles, as in Phanaeus (Fig. 18). The old belief that rudiments have been created to complete the scheme of nature is here so far from holding good, that we have a complete inversion of the ordinary state of things in the family. We may reasonably suspect that the males originally bore horns and transferred them to the females in a rudimentary condition, as in so many other Lamellicorns. Why the males subsequently lost their horns, we know not; but this may have been caused through the principle of compensation, owing to the development of the large horns and projections on the lower surface; and as these are confined to the males, the rudiments of the upper horns on the females would not have been thus obliterated. [Fig. 23. Bledius taurus, magnified. Left-hand figure, male; right-hand figure, female.] The cases hitherto given refer to the Lamellicorns, but the males of some few other beetles, belonging to two widely distinct groups, namely, the Curculionidae and Staphylinidae, are furnished with horns--in the former on the lower surface of the body (66. Kirby and Spence, 'Introduction to Entomology,' vol. iii. p. 329.), in the latter on the upper surface of the head and thorax. In the Staphylinidae, the horns of the males are extraordinarily variable in the same species, just as we have seen with the Lamellicorns. In Siagonium we have a case of dimorphism, for the males can be divided into two sets, differing greatly in the size of their bodies and in the development of their horns, without intermediate gradations. In a species of Bledius (Fig. 23), also belonging to the Staphylinidae, Professor Westwood states that, "male specimens can be found in the same locality in which the central horn of the thorax is very large, but the horns of the head quite rudimental; and others, in which the thoracic horn is much shorter, whilst the protuberances on the head are long." (67. 'Modern Classification of Insects,' vol. i. p. 172: Siagonium, p. 172. In the British Museum I noticed one male specimen of Siagonium in an intermediate condition, so that the dimorphism is not strict.) Here we apparently have a case of compensation, which throws light on that just given, of the supposed loss of the upper horns by the males of Onitis. LAW OF BATTLE. Some male beetles, which seem ill-fitted for fighting, nevertheless engage in conflicts for the possession of the females. Mr. Wallace (68. 'The Malay Archipelago,' vol. ii. 1869, p. 276. Riley, Sixth 'Report on Insects of Missouri,' 1874, p. 115.) saw two males of Leptorhynchus angustatus, a linear beetle with a much elongated rostrum, "fighting for a female, who stood close by busy at her boring. They pushed at each other with their rostra, and clawed and thumped, apparently in the greatest rage." The smaller male, however, "soon ran away, acknowledging himself vanquished." In some few cases male beetles are well adapted for fighting, by possessing great toothed mandibles, much larger than those of the females. This is the case with the common stag-beetle (Lucanus cervus), the males of which emerge from the pupal state about a week before the other sex, so that several may often be seen pursuing the same female. At this season they engage in fierce conflicts. When Mr. A.H. Davis (69. 'Entomological Magazine,' vol. i. 1833, p. 82. See also on the conflicts of this species, Kirby and Spence, ibid. vol. iii. p. 314; and Westwood, ibid. vol. i. p. 187.) enclosed two males with one female in a box, the larger male severely pinched the smaller one, until he resigned his pretensions. A friend informs me that when a boy he often put the males together to see them fight, and he noticed that they were much bolder and fiercer than the females, as with the higher animals. The males would seize hold of his finger, if held in front of them, but not so the females, although they have stronger jaws. The males of many of the Lucanidae, as well as of the above-mentioned Leptorhynchus, are larger and more powerful insects than the females. The two sexes of Lethrus cephalotes (one of the Lamellicorns) inhabit the same burrow; and the male has larger mandibles than the female. If, during the breeding-season, a strange male attempts to enter the burrow, he is attacked; the female does not remain passive, but closes the mouth of the burrow, and encourages her mate by continually pushing him on from behind; and the battle lasts until the aggressor is killed or runs away. (70. Quoted from Fischer, in 'Dict. Class. d'Hist. Nat.' tom. x. p. 324.) The two sexes of another Lamellicorn beetle, the Ateuchus cicatricosus, live in pairs, and seem much attached to each other; the male excites the females to roll the balls of dung in which the ova are deposited; and if she is removed, he becomes much agitated. If the male is removed the female ceases all work, and as M. Brulerie believes, would remain on the same spot until she died. (71. 'Ann. Soc. Entomolog. France,' 1866, as quoted in 'Journal of Travel,' by A. Murray, 1868, p. 135.) [Fig. 24. Chiasognathus Grantii, reduced. Upper figure, male; lower figure, female.] The great mandibles of the male Lucanidae are extremely variable both in size and structure, and in this respect resemble the horns on the head and thorax of many male Lamellicorns and Staphylinidae. A perfect series can be formed from the best-provided to the worst-provided or degenerate males. Although the mandibles of the common stag-beetle, and probably of many other species, are used as efficient weapons for fighting, it is doubtful whether their great size can thus be accounted for. We have seen that they are used by the Lucanus elaphus of N. America for seizing the female. As they are so conspicuous and so elegantly branched, and as owing to their great length they are not well adapted for pinching, the suspicion has crossed my mind that they may in addition serve as an ornament, like the horns on the head and thorax of the various species above described. The male Chiasognathus grantii of S. Chile--a splendid beetle belonging to the same family--has enormously developed mandibles (Fig. 24); he is bold and pugnacious; when threatened he faces round, opens his great jaws, and at the same time stridulates loudly. But the mandibles were not strong enough to pinch my finger so as to cause actual pain. Sexual selection, which implies the possession of considerable perceptive powers and of strong passions, seems to have been more effective with the Lamellicorns than with any other family of beetles. With some species the males are provided with weapons for fighting; some live in pairs and shew mutual affection; many have the power of stridulating when excited; many are furnished with the most extraordinary horns, apparently for the sake of ornament; and some, which are diurnal in their habits, are gorgeously coloured. Lastly, several of the largest beetles in the world belong to this family, which was placed by Linnaeus and Fabricius as the head of the Order. (72. Westwood, 'Modern Classification,' vol. i. p. 184.) STRIDULATING ORGANS. Beetles belonging to many and widely distinct families possess these organs. The sound thus produced can sometimes be heard at the distance of several feet or even yards (73. Wollaston, 'On Certain Musical Curculionidae,' 'Annals and Mag. of Nat. Hist.' vol. vi. 1860, p. 14.), but it is not comparable with that made by the Orthoptera. The rasp generally consists of a narrow, slightly-raised surface, crossed by very fine, parallel ribs, sometimes so fine as to cause iridescent colours, and having a very elegant appearance under the microscope. In some cases, as with Typhoeus, minute, bristly or scale-like prominences, with which the whole surrounding surface is covered in approximately parallel lines, could be traced passing into the ribs of the rasp. The transition takes place by their becoming confluent and straight, and at the same time more prominent and smooth. A hard ridge on an adjoining part of the body serves as the scraper for the rasp, but this scraper in some cases has been specially modified for the purpose. It is rapidly moved across the rasp, or conversely the rasp across the scraper. [Fig.25. Necrophorus (from Landois). r. The two rasps. Left-hand figure, part of the rasp highly magnified.] These organs are situated in widely different positions. In the carrion-beetles (Necrophorus) two parallel rasps (r, Fig. 25) stand on the dorsal surface of the fifth abdominal segment, each rasp (74. Landois, 'Zeitschrift fur wissenschaft Zoolog.' B. xvii. 1867, s. 127.) consisting of 126 to 140 fine ribs. These ribs are scraped against the posterior margins of the elytra, a small portion of which projects beyond the general outline. In many Crioceridae, and in Clythra 4-punctata (one of the Chrysomelidae), and in some Tenebrionidae, etc. (75. I am greatly indebted to Mr. G.R. Crotch for having sent me many prepared specimens of various beetles belonging to these three families and to others, as well as for valuable information. He believes that the power of stridulation in the Clythra has not been previously observed. I am also much indebted to Mr. E.W. Janson, for information and specimens. I may add that my son, Mr. F. Darwin, finds that Dermestes murinus stridulates, but he searched in vain for the apparatus. Scolytus has lately been described by Dr. Chapman as a stridulator, in the 'Entomologist's Monthly Magazine,' vol. vi. p. 130.), the rasp is seated on the dorsal apex of the abdomen, on the pygidium or pro-pygidium, and is scraped in the same manner by the elytra. In Heterocerus, which belongs to another family, the rasps are placed on the sides of the first abdominal segment, and are scraped by ridges on the femora. (76. Schiodte, translated, in 'Annals and Magazine of Natural History,' vol. xx. 1867, p. 37.) In certain Curculionidae and Carabidae (77. Westring has described (Kroyer, 'Naturhist. Tidskrift,' B. ii. 1848-49, p. 334) the stridulating organs in these two, as well as in other families. In the Carabidae I have examined Elaphrus uliginosus and Blethisa multipunctata, sent to me by Mr. Crotch. In Blethisa the transverse ridges on the furrowed border of the abdominal segment do not, as far as I could judge, come into play in scraping the rasps on the elytra.), the parts are completely reversed in position, for the rasps are seated on the inferior surface of the elytra, near their apices, or along their outer margins, and the edges of the abdominal segments serve as the scrapers. In Pelobius Hermanni (one of Dytiscidae or water-beetles) a strong ridge runs parallel and near to the sutural margin of the elytra, and is crossed by ribs, coarse in the middle part, but becoming gradually finer at both ends, especially at the upper end; when this insect is held under water or in the air, a stridulating noise is produced by the extreme horny margin of the abdomen being scraped against the rasps. In a great number of long-horned beetles (Longicornia) the organs are situated quite otherwise, the rasp being on the meso-thorax, which is rubbed against the pro-thorax; Landois counted 238 very fine ribs on the rasp of Cerambyx heros. [Fig.26. Hind-leg of Geotrupes stercorarius (from Landois). r. Rasp. c. Coxa. f. Femur. t. Tibia. tr. Tarsi.] Many Lamellicorns have the power of stridulating, and the organs differ greatly in position. Some species stridulate very loudly, so that when Mr. F. Smith caught a Trox sabulosus, a gamekeeper, who stood by, thought he had caught a mouse; but I failed to discover the proper organs in this beetle. In Geotrupes and Typhoeus, a narrow ridge runs obliquely across (r, Fig. 26) the coxa of each hind-leg (having in G. stercorarius 84 ribs), which is scraped by a specially projecting part of one of the abdominal segments. In the nearly allied Copris lunaris, an excessively narrow fine rasp runs along the sutural margin of the elytra, with another short rasp near the basal outer margin; but in some other Coprini the rasp is seated, according to Leconte (78. I am indebted to Mr. Walsh, of Illinois, for having sent me extracts from Leconte's 'Introduction to Entomology,' pp. 101, 143.), on the dorsal surface of the abdomen. In Oryctes it is seated on the pro-pygidium; and, according to the same entomologist, in some other Dynastini, on the under surface of the elytra. Lastly, Westring states that in Omaloplia brunnea the rasp is placed on the pro-sternum, and the scraper on the meta-sternum, the parts thus occupying the under surface of the body, instead of the upper surface as in the Longicorns. We thus see that in the different coleopterous families the stridulating organs are wonderfully diversified in position, but not much in structure. Within the same family some species are provided with these organs, and others are destitute of them. This diversity is intelligible, if we suppose that originally various beetles made a shuffling or hissing noise by the rubbing together of any hard and rough parts of their bodies, which happened to be in contact; and that from the noise thus produced being in some way useful, the rough surfaces were gradually developed into regular stridulating organs. Some beetles as they move, now produce, either intentionally or unintentionally, a shuffling noise, without possessing any proper organs for the purpose. Mr. Wallace informs me that the Euchirus longimanus (a Lamellicorn, with the anterior legs wonderfully elongated in the male) "makes, whilst moving, a low hissing sound by the protrusion and contraction of the abdomen; and when seized it produces a grating sound by rubbing its hind-legs against the edges of the elytra." The hissing sound is clearly due to a narrow rasp running along the sutural margin of each elytron; and I could likewise make the grating sound by rubbing the shagreened surface of the femur against the granulated margin of the corresponding elytron; but I could not here detect any proper rasp; nor is it likely that I could have overlooked it in so large an insect. After examining Cychrus, and reading what Westring has written about this beetle, it seems very doubtful whether it possesses any true rasp, though it has the power of emitting a sound. From the analogy of the Orthoptera and Homoptera, I expected to find the stridulating organs in the Coleoptera differing according to sex; but Landois, who has carefully examined several species, observed no such difference; nor did Westring; nor did Mr. G.R. Crotch in preparing the many specimens which he had the kindness to send me. Any difference in these organs, if slight, would, however, be difficult to detect, on account of their great variability. Thus, in the first pair of specimens of Necrophorus humator and of Pelobius which I examined, the rasp was considerably larger in the male than in the female; but not so with succeeding specimens. In Geotrupes stercorarius the rasp appeared to me thicker, opaquer, and more prominent in three males than in the same number of females; in order, therefore, to discover whether the sexes differed in their power of stridulating, my son, Mr. F. Darwin, collected fifty-seven living specimens, which he separated into two lots, according as they made a greater or lesser noise, when held in the same manner. He then examined all these specimens, and found that the males were very nearly in the same proportion to the females in both the lots. Mr. F. Smith has kept alive numerous specimens of Monoynchus pseudacori (Curculionidae), and is convinced that both sexes stridulate, and apparently in an equal degree. Nevertheless, the power of stridulating is certainly a sexual character in some few Coleoptera. Mr. Crotch discovered that the males alone of two species of Heliopathes (Tenebrionidae) possess stridulating organs. I examined five males of H. gibbus, and in all these there was a well-developed rasp, partially divided into two, on the dorsal surface of the terminal abdominal segment; whilst in the same number of females there was not even a rudiment of the rasp, the membrane of this segment being transparent, and much thinner than in the male. In H. cribratostriatus the male has a similar rasp, excepting that it is not partially divided into two portions, and the female is completely destitute of this organ; the male in addition has on the apical margins of the elytra, on each side of the suture, three or four short longitudinal ridges, which are crossed by extremely fine ribs, parallel to and resembling those on the abdominal rasp; whether these ridges serve as an independent rasp, or as a scraper for the abdominal rasp, I could not decide: the female exhibits no trace of this latter structure. Again, in three species of the Lamellicorn genus Oryctes, we have a nearly parallel case. In the females of O. gryphus and nasicornis the ribs on the rasp of the pro-pygidium are less continuous and less distinct than in the males; but the chief difference is that the whole upper surface of this segment, when held in the proper light, is seen to be clothed with hairs, which are absent or are represented by excessively fine down in the males. It should be noticed that in all Coleoptera the effective part of the rasp is destitute of hairs. In O. senegalensis the difference between the sexes is more strongly marked, and this is best seen when the proper abdominal segment is cleaned and viewed as a transparent object. In the female the whole surface is covered with little separate crests, bearing spines; whilst in the male these crests in proceeding towards the apex, become more and more confluent, regular, and naked; so that three-fourths of the segment is covered with extremely fine parallel ribs, which are quite absent in the female. In the females, however, of all three species of Oryctes, a slight grating or stridulating sound is produced, when the abdomen of a softened specimen is pushed backwards and forwards. In the case of the Heliopathes and Oryctes there can hardly be a doubt that the males stridulate in order to call or to excite the females; but with most beetles the stridulation apparently serves both sexes as a mutual call. Beetles stridulate under various emotions, in the same manner as birds use their voices for many purposes besides singing to their mates. The great Chiasognathus stridulates in anger or defiance; many species do the same from distress or fear, if held so that they cannot escape; by striking the hollow stems of trees in the Canary Islands, Messrs. Wollaston and Crotch were able to discover the presence of beetles belonging to the genus Acalles by their stridulation. Lastly, the male Ateuchus stridulates to encourage the female in her work, and from distress when she is removed. (79. M. P. de la Brulerie, as quoted in 'Journal of Travel,' A. Murray, vol. i. 1868, p. 135.) Some naturalists believe that beetles make this noise to frighten away their enemies; but I cannot think that a quadruped or bird, able to devour a large beetle, would be frightened by so slight a sound. The belief that the stridulation serves as a sexual call is supported by the fact that death-ticks (Anobium tessellatum) are well known to answer each other's ticking, and, as I have myself observed, a tapping noise artificially made. Mr. Doubleday also informs me that he has sometimes observed a female ticking (80. According to Mr. Doubleday, "the noise is produced by the insect raising itself on its legs as high as it can, and then striking its thorax five or six times, in rapid succession, against the substance upon which it is sitting." For references on this subject see Landois, 'Zeitschrift für wissen. Zoolog.' B. xvii. s. 131. Olivier says (as quoted by Kirby and Spence, 'Introduction to Entomology,' vol. ii. p. 395) that the female of Pimelia striata produces a rather loud sound by striking her abdomen against any hard substance, "and that the male, obedient to this call, soon attends her, and they pair."), and in an hour or two afterwards has found her united with a male, and on one occasion surrounded by several males. Finally, it is probable that the two sexes of many kinds of beetles were at first enabled to find each other by the slight shuffling noise produced by the rubbing together of the adjoining hard parts of their bodies; and that as those males or females which made the greatest noise succeeded best in finding partners, rugosities on various parts of their bodies were gradually developed by means of sexual selection into true stridulating organs. CHAPTER XI. INSECTS, continued. ORDER LEPIDOPTERA. (BUTTERFLIES AND MOTHS.) Courtship of butterflies--Battles--Ticking noise--Colours common to both sexes, or more brilliant in the males--Examples--Not due to the direct action of the conditions of life--Colours adapted for protection--Colours of moths--Display--Perceptive powers of the Lepidoptera--Variability--Causes of the difference in colour between the males and females--Mimicry, female butterflies more brilliantly coloured than the males--Bright colours of caterpillars--Summary and concluding remarks on the secondary sexual characters of insects--Birds and insects compared. In this great Order the most interesting points for us are the differences in colour between the sexes of the same species, and between the distinct species of the same genus. Nearly the whole of the following chapter will be devoted to this subject; but I will first make a few remarks on one or two other points. Several males may often be seen pursuing and crowding round the same female. Their courtship appears to be a prolonged affair, for I have frequently watched one or more males pirouetting round a female until I was tired, without seeing the end of the courtship. Mr. A.G. Butler also informs me that he has several times watched a male courting a female for a full quarter of an hour; but she pertinaciously refused him, and at last settled on the ground and closed her wings, so as to escape from his addresses. Although butterflies are weak and fragile creatures, they are pugnacious, and an emperor butterfly (1. Apatura Iris: 'The Entomologist's Weekly Intelligence,' 1859, p. 139. For the Bornean Butterflies, see C. Collingwood, 'Rambles of a Naturalist,' 1868, p. 183.) has been captured with the tips of its wings broken from a conflict with another male. Mr. Collingwood, in speaking of the frequent battles between the butterflies of Borneo, says, "They whirl round each other with the greatest rapidity, and appear to be incited by the greatest ferocity." The Ageronia feronia makes a noise like that produced by a toothed wheel passing under a spring catch, and which can be heard at the distance of several yards: I noticed this sound at Rio de Janeiro, only when two of these butterflies were chasing each other in an irregular course, so that it is probably made during the courtship of the sexes. (2. See my 'Journal of Researches,' 1845, p. 33. Mr. Doubleday has detected ('Proc. Ent. Soc.' March 3, 1845, p. 123) a peculiar membranous sac at the base of the front wings, which is probably connected with the production of the sound. For the case of Thecophora, see 'Zoological Record,' 1869, p. 401. For Mr. Buchanan White's observations, the Scottish Naturalist, July 1872, p. 214.) Some moths also produce sounds; for instance, the males Theocophora fovea. On two occasions Mr. F. Buchanan White (3. 'The Scottish Naturalist,' July 1872, p. 213.) heard a sharp quick noise made by the male of Hylophila prasinana, and which he believes to be produced, as in Cicada, by an elastic membrane, furnished with a muscle. He quotes, also, Guenee, that Setina produces a sound like the ticking of a watch, apparently by the aid of "two large tympaniform vesicles, situated in the pectoral region"; and these "are much more developed in the male than in the female." Hence the sound-producing organs in the Lepidoptera appear to stand in some relation with the sexual functions. I have not alluded to the well-known noise made by the Death's Head Sphinx, for it is generally heard soon after the moth has emerged from its cocoon. Giard has always observed that the musky odour, which is emitted by two species of Sphinx moths, is peculiar to the males (4. 'Zoological Record,' 1869, p. 347.); and in the higher classes we shall meet with many instances of the males alone being odoriferous. Every one must have admired the extreme beauty of many butterflies and of some moths; and it may be asked, are their colours and diversified patterns the result of the direct action of the physical conditions to which these insects have been exposed, without any benefit being thus derived? Or have successive variations been accumulated and determined as a protection, or for some unknown purpose, or that one sex may be attractive to the other? And, again, what is the meaning of the colours being widely different in the males and females of certain species, and alike in the two sexes of other species of the same genus? Before attempting to answer these questions a body of facts must be given. With our beautiful English butterflies, the admiral, peacock, and painted lady (Vanessae), as well as many others, the sexes are alike. This is also the case with the magnificent Heliconidae, and most of the Danaidae in the tropics. But in certain other tropical groups, and in some of our English butterflies, as the purple emperor, orange-tip, etc. (Apatura Iris and Anthocharis cardamines), the sexes differ either greatly or slightly in colour. No language suffices to describe the splendour of the males of some tropical species. Even within the same genus we often find species presenting extraordinary differences between the sexes, whilst others have their sexes closely alike. Thus in the South American genus Epicalia, Mr. Bates, to whom I am indebted for most of the following facts, and for looking over this whole discussion, informs me that he knows twelve species, the two sexes of which haunt the same stations (and this is not always the case with butterflies), and which, therefore, cannot have been differently affected by external conditions. (5. See also Mr. Bates's paper in 'Proc. Ent. Soc. of Philadelphia,' 1865, p. 206. Also Mr. Wallace on the same subject, in regard to Diadema, in 'Transactions, Entomological Society of London,' 1869, p. 278.) In nine of these twelve species the males rank amongst the most brilliant of all butterflies, and differ so greatly from the comparatively plain females that they were formerly placed in distinct genera. The females of these nine species resemble each other in their general type of coloration; and they likewise resemble both sexes of the species in several allied genera found in various parts of the world. Hence we may infer that these nine species, and probably all the others of the genus, are descended from an ancestral form which was coloured in nearly the same manner. In the tenth species the female still retains the same general colouring, but the male resembles her, so that he is coloured in a much less gaudy and contrasted manner than the males of the previous species. In the eleventh and twelfth species, the females depart from the usual type, for they are gaily decorated almost like the males, but in a somewhat less degree. Hence in these two latter species the bright colours of the males seem to have been transferred to the females; whilst in the tenth species the male has either retained or recovered the plain colours of the female, as well as of the parent-form of the genus. The sexes in these three cases have thus been rendered nearly alike, though in an opposite manner. In the allied genus Eubagis, both sexes of some of the species are plain-coloured and nearly alike; whilst with the greater number the males are decorated with beautiful metallic tints in a diversified manner, and differ much from their females. The females throughout the genus retain the same general style of colouring, so that they resemble one another much more closely than they resemble their own males. In the genus Papilio, all the species of the Aeneas group are remarkable for their conspicuous and strongly contrasted colours, and they illustrate the frequent tendency to gradation in the amount of difference between the sexes. In a few species, for instance in P. ascanius, the males and females are alike; in others the males are either a little brighter, or very much more superb than the females. The genus Junonia, allied to our Vanessae, offers a nearly parallel case, for although the sexes of most of the species resemble each other, and are destitute of rich colours, yet in certain species, as in J. oenone, the male is rather more bright-coloured than the female, and in a few (for instance J. andremiaja) the male is so different from the female that he might be mistaken for an entirely distinct species. Another striking case was pointed out to me in the British Museum by Mr. A. Butler, namely, one of the tropical American Theclae, in which both sexes are nearly alike and wonderfully splendid; in another species the male is coloured in a similarly gorgeous manner, whilst the whole upper surface of the female is of a dull uniform brown. Our common little English blue butterflies of the genus Lycaena, illustrate the various differences in colour between the sexes, almost as well, though not in so striking a manner, as the above exotic genera. In Lycaena agestis both sexes have wings of a brown colour, bordered with small ocellated orange spots, and are thus alike. In L. oegon the wings of the males are of a fine blue, bordered with black, whilst those of the female are brown, with a similar border, closely resembling the wings of L. agestis. Lastly, in L. arion both sexes are of a blue colour and are very like, though in the female the edges of the wings are rather duskier, with the black spots plainer; and in a bright blue Indian species both sexes are still more alike. I have given the foregoing details in order to shew, in the first place, that when the sexes of butterflies differ, the male as a general rule is the more beautiful, and departs more from the usual type of colouring of the group to which the species belongs. Hence in most groups the females of the several species resemble each other much more closely than do the males. In some cases, however, to which I shall hereafter allude, the females are coloured more splendidly than the males. In the second place, these details have been given to bring clearly before the mind that within the same genus, the two sexes frequently present every gradation from no difference in colour, to so great a difference that it was long before the two were placed by entomologists in the same genus. In the third place, we have seen that when the sexes nearly resemble each other, this appears due either to the male having transferred his colours to the female, or to the male having retained, or perhaps recovered, the primordial colours of the group. It also deserves notice that in those groups in which the sexes differ, the females usually somewhat resemble the males, so that when the males are beautiful to an extraordinary degree, the females almost invariably exhibit some degree of beauty. From the many cases of gradation in the amount of difference between the sexes, and from the prevalence of the same general type of coloration throughout the whole of the same group, we may conclude that the causes have generally been the same which have determined the brilliant colouring of the males alone of some species, and of both sexes of other species. As so many gorgeous butterflies inhabit the tropics, it has often been supposed that they owe their colours to the great heat and moisture of these zones; but Mr. Bates (6. 'The Naturalist on the Amazons,' vol. i. 1863, p. 19.) has shown by the comparison of various closely-allied groups of insects from the temperate and tropical regions, that this view cannot be maintained; and the evidence becomes conclusive when brilliantly-coloured males and plain-coloured females of the same species inhabit the same district, feed on the same food, and follow exactly the same habits of life. Even when the sexes resemble each other, we can hardly believe that their brilliant and beautifully-arranged colours are the purposeless result of the nature of the tissues and of the action of the surrounding conditions. With animals of all kinds, whenever colour has been modified for some special purpose, this has been, as far as we can judge, either for direct or indirect protection, or as an attraction between the sexes. With many species of butterflies the upper surfaces of the wings are obscure; and this in all probability leads to their escaping observation and danger. But butterflies would be particularly liable to be attacked by their enemies when at rest; and most kinds whilst resting raise their wings vertically over their backs, so that the lower surface alone is exposed to view. Hence it is this side which is often coloured so as to imitate the objects on which these insects commonly rest. Dr. Rossler, I believe, first noticed the similarity of the closed wings of certain Vanessae and other butterflies to the bark of trees. Many analogous and striking facts could be given. The most interesting one is that recorded by Mr. Wallace (7. See the interesting article in the 'Westminster Review,' July 1867, p. 10. A woodcut of the Kallima is given by Mr. Wallace in 'Hardwicke's Science Gossip,' September 1867, p. 196.) of a common Indian and Sumatran butterfly (Kallima) which disappears like magic when it settles on a bush; for it hides its head and antennae between its closed wings, which, in form, colour and veining, cannot be distinguished from a withered leaf with its footstalk. In some other cases the lower surfaces of the wings are brilliantly coloured, and yet are protective; thus in Thecla rubi the wings when closed are of an emerald green, and resemble the young leaves of the bramble, on which in spring this butterfly may often be seen seated. It is also remarkable that in very many species in which the sexes differ greatly in colour on their upper surface, the lower surface is closely similar or identical in both sexes, and serves as a protection. (8. Mr. G. Fraser, in 'Nature,' April 1871, p. 489.) Although the obscure tints both of the upper and under sides of many butterflies no doubt serve to conceal them, yet we cannot extend this view to the brilliant and conspicuous colours on the upper surface of such species as our admiral and peacock Vanessae, our white cabbage-butterflies (Pieris), or the great swallow-tail Papilio which haunts the open fens--for these butterflies are thus rendered visible to every living creature. In these species both sexes are alike; but in the common brimstone butterfly (Gonepteryx rhamni), the male is of an intense yellow, whilst the female is much paler; and in the orange-tip (Anthocharis cardamines) the males alone have their wings tipped with bright orange. Both the males and females in these cases are conspicuous, and it is not credible that their difference in colour should stand in any relation to ordinary protection. Prof. Weismann remarks (9. 'Einfluss der Isolirung auf die Artbildung,' 1872, p. 58.), that the female of one of the Lycaenae expands her brown wings when she settles on the ground, and is then almost invisible; the male, on the other hand, as if aware of the danger incurred from the bright blue of the upper surface of his wings, rests with them closed; and this shows that the blue colour cannot be in any way protective. Nevertheless, it is probable that conspicuous colours are indirectly beneficial to many species, as a warning that they are unpalatable. For in certain other cases, beauty has been gained through the imitation of other beautiful species, which inhabit the same district and enjoy an immunity from attack by being in some way offensive to their enemies; but then we have to account for the beauty of the imitated species. As Mr. Walsh has remarked to me, the females of our orange-tip butterfly, above referred to, and of an American species (Anth. genutia) probably shew us the primordial colours of the parent-species of the genus; for both sexes of four or five widely-distributed species are coloured in nearly the same manner. As in several previous cases, we may here infer that it is the males of Anth. cardamines and genutia which have departed from the usual type of the genus. In the Anth. sara from California, the orange-tips to the wings have been partially developed in the female; but they are paler than in the male, and slightly different in some other respects. In an allied Indian form, the Iphias glaucippe, the orange-tips are fully developed in both sexes. In this Iphias, as pointed out to me by Mr. A. Butler, the under surface of the wings marvellously resembles a pale-coloured leaf; and in our English orange-tip, the under surface resembles the flower-head of the wild parsley, on which the butterfly often rests at night. (10. See the interesting observations by T.W. Wood, 'The Student,' Sept. 1868, p. 81.) The same reason which compels us to believe that the lower surfaces have here been coloured for the sake of protection, leads us to deny that the wings have been tipped with bright orange for the same purpose, especially when this character is confined to the males. Most Moths rest motionless during the whole or greater part of the day with their wings depressed; and the whole upper surface is often shaded and coloured in an admirable manner, as Mr. Wallace has remarked, for escaping detection. The front-wings of the Bombycidae and Noctuidae (11. Mr. Wallace in 'Hardwicke's Science Gossip,' September 1867, p. 193.), when at rest, generally overlap and conceal the hind-wings; so that the latter might be brightly coloured without much risk; and they are in fact often thus coloured. During flight, moths would often be able to escape from their enemies; nevertheless, as the hind-wings are then fully exposed to view, their bright colours must generally have been acquired at some little risk. But the following fact shews how cautious we ought to be in drawing conclusions on this head. The common Yellow Under-wings (Triphaena) often fly about during the day or early evening, and are then conspicuous from the colour of their hind-wings. It would naturally be thought that this would be a source of danger; but Mr. J. Jenner Weir believes that it actually serves them as a means of escape, for birds strike at these brightly coloured and fragile surfaces, instead of at the body. For instance, Mr. Weir turned into his aviary a vigorous specimen of Triphaena pronuba, which was instantly pursued by a robin; but the bird's attention being caught by the coloured wings, the moth was not captured until after about fifty attempts, and small portions of the wings were repeatedly broken off. He tried the same experiment, in the open air, with a swallow and T. fimbria; but the large size of this moth probably interfered with its capture. (12. See also, on this subject, Mr. Weir's paper in 'Transactions, Entomological Society,' 1869, p. 23.) We are thus reminded of a statement made by Mr. Wallace (13. 'Westminster Review,' July 1867, p. 16.), namely, that in the Brazilian forests and Malayan islands, many common and highly-decorated butterflies are weak flyers, though furnished with a broad expanse of wing; and they "are often captured with pierced and broken wings, as if they had been seized by birds, from which they had escaped: if the wings had been much smaller in proportion to the body, it seems probable that the insect would more frequently have been struck or pierced in a vital part, and thus the increased expanse of the wings may have been indirectly beneficial." DISPLAY. The bright colours of many butterflies and of some moths are specially arranged for display, so that they may be readily seen. During the night colours are not visible, and there can be no doubt that the nocturnal moths, taken as a body, are much less gaily decorated than butterflies, all of which are diurnal in their habits. But the moths of certain families, such as the Zygaenidae, several Sphingidae, Uraniidae, some Arctiidae and Saturniidae, fly about during the day or early evening, and many of these are extremely beautiful, being far brighter coloured than the strictly nocturnal kinds. A few exceptional cases, however, of bright-coloured nocturnal species have been recorded. (14. For instance, Lithosia; but Prof. Westwood ('Modern Class. of Insects,' vol. ii. p. 390) seems surprised at this case. On the relative colours of diurnal and nocturnal Lepidoptera, see ibid. pp. 333 and 392; also Harris, 'Treatise on the Insects of New England,' 1842, p. 315.) There is evidence of another kind in regard to display. Butterflies, as before remarked, elevate their wings when at rest, but whilst basking in the sunshine often alternately raise and depress them, thus exposing both surfaces to full view; and although the lower surface is often coloured in an obscure manner as a protection, yet in many species it is as highly decorated as the upper surface, and sometimes in a very different manner. In some tropical species the lower surface is even more brilliantly coloured than the upper. (15. Such differences between the upper and lower surfaces of the wings of several species of Papilio may be seen in the beautiful plates to Mr. Wallace's 'Memoir on the Papilionidae of the Malayan Region,' in 'Transactions of the Linnean Society,' vol. xxv. part i. 1865.) In the English fritillaries (Argynnis) the lower surface alone is ornamented with shining silver. Nevertheless, as a general rule, the upper surface, which is probably more fully exposed, is coloured more brightly and diversely than the lower. Hence the lower surface generally affords to entomologists the more useful character for detecting the affinities of the various species. Fritz Müller informs me that three species of Castnia are found near his house in S. Brazil: of two of them the hind-wings are obscure, and are always covered by the front-wings when these butterflies are at rest; but the third species has black hind-wings, beautifully spotted with red and white, and these are fully expanded and displayed whenever the butterfly rests. Other such cases could be added. If we now turn to the enormous group of moths, which, as I hear from Mr. Stainton, do not habitually expose the under surface of their wings to full view, we find this side very rarely coloured with a brightness greater than, or even equal to, that of the upper side. Some exceptions to the rule, either real or apparent, must be noticed, as the case of Hypopyra. (16. See Mr. Wormald on this moth: 'Proceedings of the Entomological Society,' March 2, 1868.) Mr. Trimen informs me that in Guenee's great work, three moths are figured, in which the under surface is much the more brilliant. For instance, in the Australian Gastrophora the upper surface of the fore-wing is pale greyish-ochreous, while the lower surface is magnificently ornamented by an ocellus of cobalt-blue, placed in the midst of a black mark, surrounded by orange-yellow, and this by bluish-white. But the habits of these three moths are unknown; so that no explanation can be given of their unusual style of colouring. Mr. Trimen also informs me that the lower surface of the wings in certain other Geometrae (17. See also an account of the S. American genus Erateina (one of the Geometrae) in 'Transactions, Ent. Soc.' new series, vol. v. pl. xv. and xvi.) and quadrifid Noctuae are either more variegated or more brightly-coloured than the upper surface; but some of these species have the habit of "holding their wings quite erect over their backs, retaining them in this position for a considerable time," and thus exposing the under surface to view. Other species, when settled on the ground or herbage, now and then suddenly and slightly lift up their wings. Hence the lower surface of the wings being brighter than the upper surface in certain moths is not so anomalous as it at first appears. The Saturniidae include some of the most beautiful of all moths, their wings being decorated, as in our British Emperor moth, with fine ocelli; and Mr. T.W. Wood (18. 'Proc Ent. Soc. of London,' July 6, 1868, p. xxvii.) observes that they resemble butterflies in some of their movements; "for instance, in the gentle waving up and down of the wings as if for display, which is more characteristic of diurnal than of nocturnal Lepidoptera." It is a singular fact that no British moths which are brilliantly coloured, and, as far as I can discover, hardly any foreign species, differ much in colour according to sex; though this is the case with many brilliant butterflies. The male, however, of one American moth, the Saturnia Io, is described as having its fore-wings deep yellow, curiously marked with purplish-red spots; whilst the wings of the female are purple-brown, marked with grey lines. (19. Harris, 'Treatise,' etc., edited by Flint, 1862, p. 395.) The British moths which differ sexually in colour are all brown, or of various dull yellow tints, or nearly white. In several species the males are much darker than the females (20. For instance, I observe in my son's cabinet that the males are darker than the females in the Lasiocampa quercus, Odonestis potatoria, Hypogymna dispar, Dasychira pudibunda, and Cycnia mendica. In this latter species the difference in colour between the two sexes is strongly marked; and Mr. Wallace informs me that we here have, as he believes, an instance of protective mimicry confined to one sex, as will hereafter be more fully explained. The white female of the Cycnia resembles the very common Spilosoma menthrasti, both sexes of which are white; and Mr. Stainton observed that this latter moth was rejected with utter disgust by a whole brood of young turkeys, which were fond of eating other moths; so that if the Cycnia was commonly mistaken by British birds for the Spilosoma, it would escape being devoured, and its white deceptive colour would thus be highly beneficial.), and these belong to groups which generally fly about during the afternoon. On the other hand, in many genera, as Mr. Stainton informs me, the males have the hind-wings whiter than those of the female--of which fact Agrotis exclamationis offers a good instance. In the Ghost Moth (Hepialus humuli) the difference is more strongly marked; the males being white, and the females yellow with darker markings. (21. It is remarkable, that in the Shetland Islands the male of this moth, instead of differing widely from the female, frequently resembles her closely in colour (see Mr. MacLachlan, 'Transactions, Entomological Society,' vol. ii. 1866, p. 459). Mr. G. Fraser suggests ('Nature,' April 1871, p. 489) that at the season of the year when the ghost-moth appears in these northern islands, the whiteness of the males would not be needed to render them visible to the females in the twilight night.) It is probable that in these cases the males are thus rendered more conspicuous, and more easily seen by the females whilst flying about in the dusk. From the several foregoing facts it is impossible to admit that the brilliant colours of butterflies, and of some few moths, have commonly been acquired for the sake of protection. We have seen that their colours and elegant patterns are arranged and exhibited as if for display. Hence I am led to believe that the females prefer or are most excited by the more brilliant males; for on any other supposition the males would, as far as we can see, be ornamented to no purpose. We know that ants and certain Lamellicorn beetles are capable of feeling an attachment for each other, and that ants recognise their fellows after an interval of several months. Hence there is no abstract improbability in the Lepidoptera, which probably stand nearly or quite as high in the scale as these insects, having sufficient mental capacity to admire bright colours. They certainly discover flowers by colour. The Humming-bird Sphinx may often be seen to swoop down from a distance on a bunch of flowers in the midst of green foliage; and I have been assured by two persons abroad, that these moths repeatedly visit flowers painted on the walls of a room, and vainly endeavour to insert their proboscis into them. Fritz Müller informs me that several kinds of butterflies in S. Brazil shew an unmistakable preference for certain colours over others: he observed that they very often visited the brilliant red flowers of five or six genera of plants, but never the white or yellow flowering species of the same and other genera, growing in the same garden; and I have received other accounts to the same effect. As I hear from Mr. Doubleday, the common white butterfly often flies down to a bit of paper on the ground, no doubt mistaking it for one of its own species. Mr. Collingwood (22. 'Rambles of a Naturalist in the Chinese Seas,' 1868, p. 182.) in speaking of the difficulty in collecting certain butterflies in the Malay Archipelago, states that "a dead specimen pinned upon a conspicuous twig will often arrest an insect of the same species in its headlong flight, and bring it down within easy reach of the net, especially if it be of the opposite sex." The courtship of butterflies is, as before remarked, a prolonged affair. The males sometimes fight together in rivalry; and many may be seen pursuing or crowding round the same female. Unless, then, the females prefer one male to another, the pairing must be left to mere chance, and this does not appear probable. If, on the other band, the females habitually, or even occasionally, prefer the more beautiful males, the colours of the latter will have been rendered brighter by degrees, and will have been transmitted to both sexes or to one sex, according to the law of inheritance which has prevailed. The process of sexual selection will have been much facilitated, if the conclusion can be trusted, arrived at from various kinds of evidence in the supplement to the ninth chapter; namely, that the males of many Lepidoptera, at least in the imago state, greatly exceed the females in number. Some facts, however, are opposed to the belief that female butterflies prefer the more beautiful males; thus, as I have been assured by several collectors, fresh females may frequently be seen paired with battered, faded, or dingy males; but this is a circumstance which could hardly fail often to follow from the males emerging from their cocoons earlier than the females. With moths of the family of the Bombycidae, the sexes pair immediately after assuming the imago state; for they cannot feed, owing to the rudimentary condition of their mouths. The females, as several entomologists have remarked to me, lie in an almost torpid state, and appear not to evince the least choice in regard to their partners. This is the case with the common silk-moth (B. mori), as I have been told by some continental and English breeders. Dr. Wallace, who has had great experience in breeding Bombyx cynthia, is convinced that the females evince no choice or preference. He has kept above 300 of these moths together, and has often found the most vigorous females mated with stunted males. The reverse appears to occur seldom; for, as he believes, the more vigorous males pass over the weakly females, and are attracted by those endowed with most vitality. Nevertheless, the Bombycidae, though obscurely-coloured, are often beautiful to our eyes from their elegant and mottled shades. I have as yet only referred to the species in which the males are brighter coloured than the females, and I have attributed their beauty to the females for many generations having chosen and paired with the more attractive males. But converse cases occur, though rarely, in which the females are more brilliant than the males; and here, as I believe, the males have selected the more beautiful females, and have thus slowly added to their beauty. We do not know why in various classes of animals the males of some few species have selected the more beautiful females instead of having gladly accepted any female, as seems to be the general rule in the animal kingdom: but if, contrary to what generally occurs with the Lepidoptera, the females were much more numerous than the males, the latter would be likely to pick out the more beautiful females. Mr. Butler shewed me several species of Callidryas in the British Museum, in some of which the females equalled, and in others greatly surpassed the males in beauty; for the females alone have the borders of their wings suffused with crimson and orange, and spotted with black. The plainer males of these species closely resemble each other, shewing that here the females have been modified; whereas in those cases, where the males are the more ornate, it is these which have been modified, the females remaining closely alike. In England we have some analogous cases, though not so marked. The females alone of two species of Thecla have a bright-purple or orange patch on their fore-wings. In Hipparchia the sexes do not differ much; but it is the female of H. janira which has a conspicuous light-brown patch on her wings; and the females of some of the other species are brighter coloured than their males. Again, the females of Colias edusa and hyale have "orange or yellow spots on the black marginal border, represented in the males only by thin streaks"; and in Pieris it is the females which "are ornamented with black spots on the fore-wings, and these are only partially present in the males." Now the males of many butterflies are known to support the females during their marriage flight; but in the species just named it is the females which support the males; so that the part which the two sexes play is reversed, as is their relative beauty. Throughout the animal kingdom the males commonly take the more active share in wooing, and their beauty seems to have been increased by the females having accepted the more attractive individuals; but with these butterflies, the females take the more active part in the final marriage ceremony, so that we may suppose that they likewise do so in the wooing; and in this case we can understand how it is that they have been rendered the more beautiful. Mr. Meldola, from whom the foregoing statements have been taken, says in conclusion: "Though I am not convinced of the action of sexual selection in producing the colours of insects, it cannot be denied that these facts are strikingly corroborative of Mr. Darwin's views." (23. 'Nature,' April 27, 1871, p. 508. Mr. Meldola quotes Donzel, in 'Soc. Ent. de France,' 1837, p. 77, on the flight of butterflies whilst pairing. See also Mr. G. Fraser, in 'Nature,' April 20, 1871, p. 489, on the sexual differences of several British butterflies.) As sexual selection primarily depends on variability, a few words must be added on this subject. In respect to colour there is no difficulty, for any number of highly variable Lepidoptera could be named. One good instance will suffice. Mr. Bates shewed me a whole series of specimens of Papilio sesostris and P. childrenae; in the latter the males varied much in the extent of the beautifully enamelled green patch on the fore-wings, and in the size of the white mark, and of the splendid crimson stripe on the hind-wings; so that there was a great contrast amongst the males between the most and the least gaudy. The male of Papilio sesostris is much less beautiful than of P. childrenae; and it likewise varies a little in the size of the green patch on the fore-wings, and in the occasional appearance of the small crimson stripe on the hind-wings, borrowed, as it would seem, from its own female; for the females of this and of many other species in the Aeneas group possess this crimson stripe. Hence between the brightest specimens of P. sesostris and the dullest of P. childrenae, there was but a small interval; and it was evident that as far as mere variability is concerned, there would be no difficulty in permanently increasing the beauty of either species by means of selection. The variability is here almost confined to the male sex; but Mr. Wallace and Mr. Bates have shewn (24. Wallace on the Papilionidae of the Malayan Region, in 'Transact. Linn. Soc.' vol. xxv. 1865, pp. 8, 36. A striking case of a rare variety, strictly intermediate between two other well-marked female varieties, is given by Mr. Wallace. See also Mr. Bates, in 'Proc. Entomolog. Soc.' Nov. 19, 1866, p. xl.) that the females of some species are extremely variable, the males being nearly constant. In a future chapter I shall have occasion to shew that the beautiful eye-like spots, or ocelli, found on the wings of many Lepidoptera, are eminently variable. I may here add that these ocelli offer a difficulty on the theory of sexual selection; for though appearing to us so ornamental, they are never present in one sex and absent in the other, nor do they ever differ much in the two sexes. (25. Mr. Bates was so kind as to lay this subject before the Entomological Society, and I have received answers to this effect from several entomologists.) This fact is at present inexplicable; but if it should hereafter be found that the formation of an ocellus is due to some change in the tissues of the wings, for instance, occurring at a very early period of development, we might expect, from what we know of the laws of inheritance, that it would be transmitted to both sexes, though arising and perfected in one sex alone. On the whole, although many serious objections may be urged, it seems probable that most of the brilliantly-coloured species of Lepidoptera owe their colours to sexual selection, excepting in certain cases, presently to be mentioned, in which conspicuous colours have been gained through mimicry as a protection. From the ardour of the male throughout the animal kingdom, he is generally willing to accept any female; and it is the female which usually exerts a choice. Hence, if sexual selection has been efficient with the Lepidoptera, the male, when the sexes differ, ought to be the more brilliantly coloured, and this undoubtedly is the case. When both sexes are brilliantly coloured and resemble each other, the characters acquired by the males appear to have been transmitted to both. We are led to this conclusion by cases, even within the same genus, of gradation from an extraordinary amount of difference to identity in colour between the two sexes. But it may be asked whether the difference in colour between the sexes may not be accounted for by other means besides sexual selection. Thus the males and females of the same species of butterfly are in several cases known (26. H.W. Bates, 'The Naturalist on the Amazons,' vol. ii. 1863, p. 228. A.R. Wallace, in 'Transactions, Linnean Society,' vol. xxv. 1865, p. 10.) to inhabit different stations, the former commonly basking in the sunshine, the latter haunting gloomy forests. It is therefore possible that different conditions of life may have acted directly on the two sexes; but this is not probable (27. On this whole subject see 'The Variation of Animals and Plants under Domestication,' 1868, vol. ii. chap. xxiii.) as in the adult state they are exposed to different conditions during a very short period; and the larvae of both are exposed to the same conditions. Mr. Wallace believes that the difference between the sexes is due not so much to the males having been modified, as to the females having in all or almost all cases acquired dull colours for the sake of protection. It seems to me, on the contrary, far more probable that it is the males which have been chiefly modified through sexual selection, the females having been comparatively little changed. We can thus understand how it is that the females of allied species generally resemble one another so much more closely than do the males. They thus shew us approximately the primordial colouring of the parent-species of the group to which they belong. They have, however, almost always been somewhat modified by the transfer to them of some of the successive variations, through the accumulation of which the males were rendered beautiful. But I do not wish to deny that the females alone of some species may have been specially modified for protection. In most cases the males and females of distinct species will have been exposed during their prolonged larval state to different conditions, and may have been thus affected; though with the males any slight change of colour thus caused will generally have been masked by the brilliant tints gained through sexual selection. When we treat of Birds, I shall have to discuss the whole question, as to how far the differences in colour between the sexes are due to the males having been modified through sexual selection for ornamental purposes, or to the females having been modified through natural selection for the sake of protection, so that I will here say but little on the subject. In all the cases in which the more common form of equal inheritance by both sexes has prevailed, the selection of bright-coloured males would tend to make the females bright-coloured; and the selection of dull-coloured females would tend to make the males dull. If both processes were carried on simultaneously, they would tend to counteract each other; and the final result would depend on whether a greater number of females from being well protected by obscure colours, or a greater number of males by being brightly-coloured and thus finding partners, succeeded in leaving more numerous offspring. In order to account for the frequent transmission of characters to one sex alone, Mr. Wallace expresses his belief that the more common form of equal inheritance by both sexes can be changed through natural selection into inheritance by one sex alone, but in favour of this view I can discover no evidence. We know from what occurs under domestication that new characters often appear, which from the first are transmitted to one sex alone; and by the selection of such variations there would not be the slightest difficulty in giving bright colours to the males alone, and at the same time or subsequently, dull colours to the females alone. In this manner the females of some butterflies and moths have, it is probable, been rendered inconspicuous for the sake of protection, and widely different from their males. I am, however, unwilling without distinct evidence to admit that two complex processes of selection, each requiring the transference of new characters to one sex alone, have been carried on with a multitude of species,--that the males have been rendered more brilliant by beating their rivals, and the females more dull-coloured by having escaped from their enemies. The male, for instance, of the common brimstone butterfly (Gonepteryx), is of a far more intense yellow than the female, though she is equally conspicuous; and it does not seem probable that she specially acquired her pale tints as a protection, though it is probable that the male acquired his bright colours as a sexual attraction. The female of Anthocharis cardamines does not possess the beautiful orange wing-tips of the male; consequently she closely resembles the white butterflies (Pieris) so common in our gardens; but we have no evidence that this resemblance is beneficial to her. As, on the other hand, she resembles both sexes of several other species of the genus inhabiting various quarters of the world, it is probable that she has simply retained to a large extent her primordial colours. Finally, as we have seen, various considerations lead to the conclusion that with the greater number of brilliantly-coloured Lepidoptera it is the male which has been chiefly modified through sexual selection; the amount of difference between the sexes mostly depending on the form of inheritance which has prevailed. Inheritance is governed by so many unknown laws or conditions, that it seems to us to act in a capricious manner (28. The 'Variation of Animals and Plants under Domestication,' vol. ii. chap. xii. p. 17.); and we can thus, to a certain extent, understand how it is that with closely allied species the sexes either differ to an astonishing degree, or are identical in colour. As all the successive steps in the process of variation are necessarily transmitted through the female, a greater or less number of such steps might readily become developed in her; and thus we can understand the frequent gradations from an extreme difference to none at all between the sexes of allied species. These cases of gradation, it may be added, are much too common to favour the supposition that we here see females actually undergoing the process of transition and losing their brightness for the sake of protection; for we have every reason to conclude that at any one time the greater number of species are in a fixed condition. MIMICRY. This principle was first made clear in an admirable paper by Mr. Bates (29. 'Transact. Linn. Soc.' vol. xxiii. 1862, p. 495.), who thus threw a flood of light on many obscure problems. It had previously been observed that certain butterflies in S. America belonging to quite distinct families, resembled the Heliconidae so closely in every stripe and shade of colour, that they could not be distinguished save by an experienced entomologist. As the Heliconidae are coloured in their usual manner, whilst the others depart from the usual colouring of the groups to which they belong, it is clear that the latter are the imitators, and the Heliconidae the imitated. Mr. Bates further observed that the imitating species are comparatively rare, whilst the imitated abound, and that the two sets live mingled together. From the fact of the Heliconidae being conspicuous and beautiful insects, yet so numerous in individuals and species, he concluded that they must be protected from the attacks of enemies by some secretion or odour; and this conclusion has now been amply confirmed (30. 'Proc. Entomological Soc.' Dec. 3, 1866, p. xlv.), especially by Mr. Belt. Hence Mr. Bates inferred that the butterflies which imitate the protected species have acquired their present marvellously deceptive appearance through variation and natural selection, in order to be mistaken for the protected kinds, and thus to escape being devoured. No explanation is here attempted of the brilliant colours of the imitated, but only of the imitating butterflies. We must account for the colours of the former in the same general manner, as in the cases previously discussed in this chapter. Since the publication of Mr. Bates' paper, similar and equally striking facts have been observed by Mr. Wallace in the Malayan region, by Mr. Trimen in South Africa, and by Mr. Riley in the United States. (31. Wallace, 'Transact. Linn. Soc.' vol. xxv. 1865 p. i.; also, 'Transact. Ent. Soc.' vol. iv. (3rd series), 1867, p. 301. Trimen, 'Linn. Transact.' vol. xxvi. 1869, p. 497. Riley, 'Third Annual Report on the Noxious Insects of Missouri,' 1871, pp. 163-168. This latter essay is valuable, as Mr. Riley here discusses all the objections which have been raised against Mr. Bates's theory.) As some writers have felt much difficulty in understanding how the first steps in the process of mimicry could have been effected through natural selection, it may be well to remark that the process probably commenced long ago between forms not widely dissimilar in colour. In this case even a slight variation would be beneficial, if it rendered the one species more like the other; and afterwards the imitated species might be modified to an extreme degree through sexual selection or other means, and if the changes were gradual, the imitators might easily be led along the same track, until they differed to an equally extreme degree from their original condition; and they would thus ultimately assume an appearance or colouring wholly unlike that of the other members of the group to which they belonged. It should also be remembered that many species of Lepidoptera are liable to considerable and abrupt variations in colour. A few instances have been given in this chapter; and many more may be found in the papers of Mr. Bates and Mr. Wallace. With several species the sexes are alike, and imitate the two sexes of another species. But Mr. Trimen gives, in the paper already referred to, three cases in which the sexes of the imitated form differ from each other in colour, and the sexes of the imitating form differ in a like manner. Several cases have also been recorded where the females alone imitate brilliantly-coloured and protected species, the males retaining "the normal aspect of their immediate congeners." It is here obvious that the successive variations by which the female has been modified have been transmitted to her alone. It is, however, probable that some of the many successive variations would have been transmitted to, and developed in, the males had not such males been eliminated by being thus rendered less attractive to the females; so that only those variations were preserved which were from the first strictly limited in their transmission to the female sex. We have a partial illustration of these remarks in a statement by Mr. Belt (32. 'The Naturalist in Nicaragua,' 1874, p. 385.); that the males of some of the Leptalides, which imitate protected species, still retain in a concealed manner some of their original characters. Thus in the males "the upper half of the lower wing is of a pure white, whilst all the rest of the wings is barred and spotted with black, red and yellow, like the species they mimic. The females have not this white patch, and the males usually conceal it by covering it with the upper wing, so that I cannot imagine its being of any other use to them than as an attraction in courtship, when they exhibit it to the females, and thus gratify their deep-seated preference for the normal colour of the Order to which the Leptalides belong." BRIGHT COLOURS OF CATERPILLARS. Whilst reflecting on the beauty of many butterflies, it occurred to me that some caterpillars were splendidly coloured; and as sexual selection could not possibly have here acted, it appeared rash to attribute the beauty of the mature insect to this agency, unless the bright colours of their larvae could be somehow explained. In the first place, it may be observed that the colours of caterpillars do not stand in any close correlation with those of the mature insect. Secondly, their bright colours do not serve in any ordinary manner as a protection. Mr. Bates informs me, as an instance of this, that the most conspicuous caterpillar which he ever beheld (that of a Sphinx) lived on the large green leaves of a tree on the open llanos of South America; it was about four inches in length, transversely banded with black and yellow, and with its head, legs, and tail of a bright red. Hence it caught the eye of any one who passed by, even at the distance of many yards, and no doubt that of every passing bird. I then applied to Mr. Wallace, who has an innate genius for solving difficulties. After some consideration he replied: "Most caterpillars require protection, as may be inferred from some kinds being furnished with spines or irritating hairs, and from many being coloured green like the leaves on which they feed, or being curiously like the twigs of the trees on which they live." Another instance of protection, furnished me by Mr. J. Mansel Weale, may be added, namely, that there is a caterpillar of a moth which lives on the mimosas in South Africa, and fabricates for itself a case quite indistinguishable from the surrounding thorns. From such considerations Mr. Wallace thought it probable that conspicuously coloured caterpillars were protected by having a nauseous taste; but as their skin is extremely tender, and as their intestines readily protrude from a wound, a slight peck from the beak of a bird would be as fatal to them as if they had been devoured. Hence, as Mr. Wallace remarks, "distastefulness alone would be insufficient to protect a caterpillar unless some outward sign indicated to its would-be destroyer that its prey was a disgusting morsel." Under these circumstances it would be highly advantageous to a caterpillar to be instantaneously and certainly recognised as unpalatable by all birds and other animals. Thus the most gaudy colours would be serviceable, and might have been gained by variation and the survival of the most easily-recognised individuals. This hypothesis appears at first sight very bold, but when it was brought before the Entomological Society (33. 'Proceedings, Entomological Society,' Dec. 3, 1866, p. xlv. and March 4, 1867, p. lxxx.) it was supported by various statements; and Mr. J. Jenner Weir, who keeps a large number of birds in an aviary, informs me that he has made many trials, and finds no exception to the rule, that all caterpillars of nocturnal and retiring habits with smooth skins, all of a green colour, and all which imitate twigs, are greedily devoured by his birds. The hairy and spinose kinds are invariably rejected, as were four conspicuously-coloured species. When the birds rejected a caterpillar, they plainly shewed, by shaking their heads, and cleansing their beaks, that they were disgusted by the taste. (34. See Mr. J. Jenner Weir's paper on Insects and Insectivorous Birds, in 'Transact. Ent. Soc.' 1869, p. 21; also Mr. Butler's paper, ibid. p. 27. Mr. Riley has given analogous facts in the 'Third Annual Report on the Noxious Insects of Missouri,' 1871, p. 148. Some opposed cases are, however, given by Dr. Wallace and M. H. d'Orville; see 'Zoological Record,' 1869, p. 349.) Three conspicuous kinds of caterpillars and moths were also given to some lizards and frogs, by Mr. A. Butler, and were rejected, though other kinds were eagerly eaten. Thus the probability of Mr. Wallace's view is confirmed, namely, that certain caterpillars have been made conspicuous for their own good, so as to be easily recognised by their enemies, on nearly the same principle that poisons are sold in coloured bottles by druggists for the good of man. We cannot, however, at present thus explain the elegant diversity in the colours of many caterpillars; but any species which had at some former period acquired a dull, mottled, or striped appearance, either in imitation of surrounding objects, or from the direct action of climate, etc., almost certainly would not become uniform in colour, when its tints were rendered intense and bright; for in order to make a caterpillar merely conspicuous, there would be no selection in any definite direction. SUMMARY AND CONCLUDING REMARKS ON INSECTS. Looking back to the several Orders, we see that the sexes often differ in various characters, the meaning of which is not in the least understood. The sexes, also, often differ in their organs of sense and means of locomotion, so that the males may quickly discover and reach the females. They differ still oftener in the males possessing diversified contrivances for retaining the females when found. We are, however, here concerned only in a secondary degree with sexual differences of these kinds. In almost all the Orders, the males of some species, even of weak and delicate kinds, are known to be highly pugnacious; and some few are furnished with special weapons for fighting with their rivals. But the law of battle does not prevail nearly so widely with insects as with the higher animals. Hence it probably arises, that it is in only a few cases that the males have been rendered larger and stronger than the females. On the contrary, they are usually smaller, so that they may be developed within a shorter time, to be ready in large numbers for the emergence of the females. In two families of the Homoptera and in three of the Orthoptera, the males alone possess sound-producing organs in an efficient state. These are used incessantly during the breeding-season, not only for calling the females, but apparently for charming or exciting them in rivalry with other males. No one who admits the agency of selection of any kind, will, after reading the above discussion, dispute that these musical instruments have been acquired through sexual selection. In four other Orders the members of one sex, or more commonly of both sexes, are provided with organs for producing various sounds, which apparently serve merely as call-notes. When both sexes are thus provided, the individuals which were able to make the loudest or most continuous noise would gain partners before those which were less noisy, so that their organs have probably been gained through sexual selection. It is instructive to reflect on the wonderful diversity of the means for producing sound, possessed by the males alone, or by both sexes, in no less than six Orders. We thus learn how effectual sexual selection has been in leading to modifications which sometimes, as with the Homoptera, relate to important parts of the organisation. From the reasons assigned in the last chapter, it is probable that the great horns possessed by the males of many Lamellicorn, and some other beetles, have been acquired as ornaments. From the small size of insects, we are apt to undervalue their appearance. If we could imagine a male Chalcosoma (Fig. 16), with its polished bronzed coat of mail, and its vast complex horns, magnified to the size of a horse, or even of a dog, it would be one of the most imposing animals in the world. The colouring of insects is a complex and obscure subject. When the male differs slightly from the female, and neither are brilliantly-coloured, it is probable that the sexes have varied in a slightly different manner, and that the variations have been transmitted by each sex to the same without any benefit or evil thus accruing. When the male is brilliantly-coloured and differs conspicuously from the female, as with some dragon-flies and many butterflies, it is probable that he owes his colours to sexual selection; whilst the female has retained a primordial or very ancient type of colouring, slightly modified by the agencies before explained. But in some cases the female has apparently been made obscure by variations transmitted to her alone, as a means of direct protection; and it is almost certain that she has sometimes been made brilliant, so as to imitate other protected species inhabiting the same district. When the sexes resemble each other and both are obscurely coloured, there is no doubt that they have been in a multitude of cases so coloured for the sake of protection. So it is in some instances when both are brightly-coloured, for they thus imitate protected species, or resemble surrounding objects such as flowers; or they give notice to their enemies that they are unpalatable. In other cases in which the sexes resemble each other and are both brilliant, especially when the colours are arranged for display, we may conclude that they have been gained by the male sex as an attraction, and have been transferred to the female. We are more especially led to this conclusion whenever the same type of coloration prevails throughout a whole group, and we find that the males of some species differ widely in colour from the females, whilst others differ slightly or not at all with intermediate gradations connecting these extreme states. In the same manner as bright colours have often been partially transferred from the males to the females, so it has been with the extraordinary horns of many Lamellicorn and some other beetles. So again, the sound-producing organs proper to the males of the Homoptera and Orthoptera have generally been transferred in a rudimentary, or even in a nearly perfect condition, to the females; yet not sufficiently perfect to be of any use. It is also an interesting fact, as bearing on sexual selection, that the stridulating organs of certain male Orthoptera are not fully developed until the last moult; and that the colours of certain male dragon-flies are not fully developed until some little time after their emergence from the pupal state, and when they are ready to breed. Sexual selection implies that the more attractive individuals are preferred by the opposite sex; and as with insects, when the sexes differ, it is the male which, with some rare exceptions, is the more ornamented, and departs more from the type to which the species belongs;--and as it is the male which searches eagerly for the female, we must suppose that the females habitually or occasionally prefer the more beautiful males, and that these have thus acquired their beauty. That the females in most or all the Orders would have the power of rejecting any particular male, is probable from the many singular contrivances possessed by the males, such as great jaws, adhesive cushions, spines, elongated legs, etc., for seizing the female; for these contrivances show that there is some difficulty in the act, so that her concurrence would seem necessary. Judging from what we know of the perceptive powers and affections of various insects, there is no antecedent improbability in sexual selection having come largely into play; but we have as yet no direct evidence on this head, and some facts are opposed to the belief. Nevertheless, when we see many males pursuing the same female, we can hardly believe that the pairing is left to blind chance--that the female exerts no choice, and is not influenced by the gorgeous colours or other ornaments with which the male is decorated. If we admit that the females of the Homoptera and Orthoptera appreciate the musical tones of their male partners, and that the various instruments have been perfected through sexual selection, there is little improbability in the females of other insects appreciating beauty in form or colour, and consequently in such characters having been thus gained by the males. But from the circumstance of colour being so variable, and from its having been so often modified for the sake of protection, it is difficult to decide in how large a proportion of cases sexual selection has played a part. This is more especially difficult in those Orders, such as Orthoptera, Hymenoptera, and Coleoptera, in which the two sexes rarely differ much in colour; for we are then left to mere analogy. With the Coleoptera, however, as before remarked, it is in the great Lamellicorn group, placed by some authors at the head of the Order, and in which we sometimes see a mutual attachment between the sexes, that we find the males of some species possessing weapons for sexual strife, others furnished with wonderful horns, many with stridulating organs, and others ornamented with splendid metallic tints. Hence it seems probable that all these characters have been gained through the same means, namely sexual selection. With butterflies we have the best evidence, as the males sometimes take pains to display their beautiful colours; and we cannot believe that they would act thus, unless the display was of use to them in their courtship. When we treat of Birds, we shall see that they present in their secondary sexual characters the closest analogy with insects. Thus, many male birds are highly pugnacious, and some are furnished with special weapons for fighting with their rivals. They possess organs which are used during the breeding-season for producing vocal and instrumental music. They are frequently ornamented with combs, horns, wattles and plumes of the most diversified kinds, and are decorated with beautiful colours, all evidently for the sake of display. We shall find that, as with insects, both sexes in certain groups are equally beautiful, and are equally provided with ornaments which are usually confined to the male sex. In other groups both sexes are equally plain-coloured and unornamented. Lastly, in some few anomalous cases, the females are more beautiful than the males. We shall often find, in the same group of birds, every gradation from no difference between the sexes, to an extreme difference. We shall see that female birds, like female insects, often possess more or less plain traces or rudiments of characters which properly belong to the males and are of use only to them. The analogy, indeed, in all these respects between birds and insects is curiously close. Whatever explanation applies to the one class probably applies to the other; and this explanation, as we shall hereafter attempt to shew in further detail, is sexual selection. CHAPTER XII. SECONDARY SEXUAL CHARACTERS OF FISHES, AMPHIBIANS, AND REPTILES. FISHES: Courtship and battles of the males--Larger size of the females--Males, bright colours and ornamental appendages; other strange characters--Colours and appendages acquired by the males during the breeding-season alone--Fishes with both sexes brilliantly coloured--Protective colours--The less conspicuous colours of the female cannot be accounted for on the principle of protection--Male fishes building nests, and taking charge of the ova and young. AMPHIBIANS: Differences in structure and colour between the sexes--Vocal organs. REPTILES: Chelonians--Crocodiles--Snakes, colours in some cases protective--Lizards, battles of--Ornamental appendages--Strange differences in structure between the sexes--Colours--Sexual differences almost as great as with birds. We have now arrived at the great sub-kingdom of the Vertebrata, and will commence with the lowest class, that of fishes. The males of Plagiostomous fishes (sharks, rays) and of Chimaeroid fishes are provided with claspers which serve to retain the female, like the various structures possessed by many of the lower animals. Besides the claspers, the males of many rays have clusters of strong sharp spines on their heads, and several rows along "the upper outer surface of their pectoral fins." These are present in the males of some species, which have other parts of their bodies smooth. They are only temporarily developed during the breeding-season; and Dr. Gunther suspects that they are brought into action as prehensile organs by the doubling inwards and downwards of the two sides of the body. It is a remarkable fact that the females and not the males of some species, as of Raia clavata, have their backs studded with large hook-formed spines. (1. Yarrell's 'Hist. of British Fishes,' vol. ii. 1836, pp 417, 425, 436. Dr. Gunther informs me that the spines in R. clavata are peculiar to the female.) The males alone of the capelin (Mallotus villosus, one of Salmonidae), are provided with a ridge of closely-set, brush-like scales, by the aid of which two males, one on each side, hold the female, whilst she runs with great swiftness on the sandy beach, and there deposits her spawn. (2. The 'American Naturalist,' April 1871, p. 119.) The widely distinct Monacanthus scopas presents a somewhat analogous structure. The male, as Dr. Gunther informs me, has a cluster of stiff, straight spines, like those of a comb, on the sides of the tail; and these in a specimen six inches long were nearly one and a half inches in length; the female has in the same place a cluster of bristles, which may be compared with those of a tooth-brush. In another species, M. peronii, the male has a brush like that possessed by the female of the last species, whilst the sides of the tail in the female are smooth. In some other species of the same genus the tail can be perceived to be a little roughened in the male and perfectly smooth in the female; and lastly in others, both sexes have smooth sides. The males of many fish fight for the possession of the females. Thus the male stickleback (Gasterosteus leiurus) has been described as "mad with delight," when the female comes out of her hiding-place and surveys the nest which he has made for her. "He darts round her in every direction, then to his accumulated materials for the nest, then back again in an instant; and as she does not advance he endeavours to push her with his snout, and then tries to pull her by the tail and side-spine to the nest." (3. See Mr. R. Warington's interesting articles in 'Annals and Magazine of Natural History,' October 1852, and November 1855.) The males are said to be polygamists (4. Noel Humphreys, 'River Gardens,' 1857.); they are extraordinarily bold and pugnacious, whilst "the females are quite pacific." Their battles are at times desperate; "for these puny combatants fasten tight on each other for several seconds, tumbling over and over again until their strength appears completely exhausted." With the rough-tailed stickleback (G. trachurus) the males whilst fighting swim round and round each other, biting and endeavouring to pierce each other with their raised lateral spines. The same writer adds (5. Loudon's 'Magazine of Natural History,' vol. iii. 1830, p. 331.), "the bite of these little furies is very severe. They also use their lateral spines with such fatal effect, that I have seen one during a battle absolutely rip his opponent quite open, so that he sank to the bottom and died." When a fish is conquered, "his gallant bearing forsakes him; his gay colours fade away; and he hides his disgrace among his peaceable companions, but is for some time the constant object of his conqueror's persecution." The male salmon is as pugnacious as the little stickleback; and so is the male trout, as I hear from Dr. Gunther. Mr. Shaw saw a violent contest between two male salmon which lasted the whole day; and Mr. R. Buist, Superintendent of Fisheries, informs me that he has often watched from the bridge at Perth the males driving away their rivals, whilst the females were spawning. The males "are constantly fighting and tearing each other on the spawning-beds, and many so injure each other as to cause the death of numbers, many being seen swimming near the banks of the river in a state of exhaustion, and apparently in a dying state." (6. The 'Field,' June 29, 1867. For Mr. Shaw's Statement, see 'Edinburgh Review,' 1843. Another experienced observer (Scrope's 'Days of Salmon Fishing,' p. 60) remarks that like the stag, the male would, if he could, keep all other males away.) Mr. Buist informs me, that in June 1868, the keeper of the Stormontfield breeding-ponds visited the northern Tyne and found about 300 dead salmon, all of which with one exception were males; and he was convinced that they had lost their lives by fighting. [Fig. 27. Head of male common salmon (Salmo salar) during the breeding-season. [This drawing, as well as all the others in the present chapter, have been executed by the well-known artist, Mr. G. Ford, from specimens in the British Museum, under the kind superintendence of Dr. Gunther.] Fig. 28. Head of female salmon.] The most curious point about the male salmon is that during the breeding-season, besides a slight change in colour, "the lower jaw elongates, and a cartilaginous projection turns upwards from the point, which, when the jaws are closed, occupies a deep cavity between the intermaxillary bones of the upper jaw." (7. Yarrell, 'History of British Fishes,' vol. ii. 1836, p. 10.) (Figs. 27 and 28.) In our salmon this change of structure lasts only during the breeding-season; but in the Salmo lycaodon of N.W. America the change, as Mr. J.K. Lord (8. 'The Naturalist in Vancouver's Island,' vol. i. 1866, p. 54.) believes, is permanent, and best marked in the older males which have previously ascended the rivers. In these old males the jaw becomes developed into an immense hook-like projection, and the teeth grow into regular fangs, often more than half an inch in length. With the European salmon, according to Mr. Lloyd (9. 'Scandinavian Adventures,' vol. i. 1854, pp. 100, 104.), the temporary hook-like structure serves to strengthen and protect the jaws, when one male charges another with wonderful violence; but the greatly developed teeth of the male American salmon may be compared with the tusks of many male mammals, and they indicate an offensive rather than a protective purpose. The salmon is not the only fish in which the teeth differ in the two sexes; as this is the case with many rays. In the thornback (Raia clavata) the adult male has sharp, pointed teeth, directed backwards, whilst those of the female are broad and flat, and form a pavement; so that these teeth differ in the two sexes of the same species more than is usual in distinct genera of the same family. The teeth of the male become sharp only when he is adult: whilst young they are broad and flat like those of the female. As so frequently occurs with secondary sexual characters, both sexes of some species of rays (for instance R. batis), when adult, possess sharp pointed teeth; and here a character, proper to and primarily gained by the male, appears to have been transmitted to the offspring of both sexes. The teeth are likewise pointed in both sexes of R. maculata, but only when quite adult; the males acquiring them at an earlier age than the females. We shall hereafter meet with analogous cases in certain birds, in which the male acquires the plumage common to both sexes when adult, at a somewhat earlier age than does the female. With other species of rays the males even when old never possess sharp teeth, and consequently the adults of both sexes are provided with broad, flat teeth like those of the young, and like those of the mature females of the above-mentioned species. (10. See Yarrell's account of the rays in his 'History of British Fishes,' vol. ii. 1836, p. 416, with an excellent figure, and pp. 422, 432.) As the rays are bold, strong and voracious fish, we may suspect that the males require their sharp teeth for fighting with their rivals; but as they possess many parts modified and adapted for the prehension of the female, it is possible that their teeth may be used for this purpose. In regard to size, M. Carbonnier (11. As quoted in 'The Farmer,' 1868, p. 369.) maintains that the female of almost all fishes is larger than the male; and Dr. Gunther does not know of a single instance in which the male is actually larger than the female. With some Cyprinodonts the male is not even half as large. As in many kinds of fishes the males habitually fight together, it is surprising that they have not generally become larger and stronger than the females through the effects of sexual selection. The males suffer from their small size, for according to M. Carbonnier, they are liable to be devoured by the females of their own species when carnivorous, and no doubt by other species. Increased size must be in some manner of more importance to the females, than strength and size are to the males for fighting with other males; and this perhaps is to allow of the production of a vast number of ova. [Fig. 29. Callionymus lyra. Upper figure, male; lower figure, female. N.B. The lower figure is more reduced than the upper.] In many species the male alone is ornamented with bright colours; or these are much brighter in the male than the female. The male, also, is sometimes provided with appendages which appear to be of no more use to him for the ordinary purposes of life, than are the tail feathers to the peacock. I am indebted for most of the following facts to the kindness of Dr. Gunther. There is reason to suspect that many tropical fishes differ sexually in colour and structure; and there are some striking cases with our British fishes. The male Callionymus lyra has been called the gemmeous dragonet "from its brilliant gem-like colours." When fresh caught from the sea the body is yellow of various shades, striped and spotted with vivid blue on the head; the dorsal fins are pale brown with dark longitudinal bands; the ventral, caudal, and anal fins being bluish-black. The female, or sordid dragonet, was considered by Linnaeus, and by many subsequent naturalists, as a distinct species; it is of a dingy reddish-brown, with the dorsal fin brown and the other fins white. The sexes differ also in the proportional size of the head and mouth, and in the position of the eyes (12. I have drawn up this description from Yarrell's 'British Fishes,' vol. i. 1836, pp. 261 and 266.); but the most striking difference is the extraordinary elongation in the male (Fig. 29) of the dorsal fin. Mr. W. Saville Kent remarks that this "singular appendage appears from my observations of the species in confinement, to be subservient to the same end as the wattles, crests, and other abnormal adjuncts of the male in gallinaceous birds, for the purpose of fascinating their mates." (13. 'Nature,' July 1873, p. 264.) The young males resemble the adult females in structure and colour. Throughout the genus Callionymus (14. 'Catalogue of Acanth. Fishes in the British Museum,' by Dr. Gunther, 1861, pp. 138-151.), the male is generally much more brightly spotted than the female, and in several species, not only the dorsal, but the anal fin is much elongated in the males. The male of the Cottus scorpius, or sea-scorpion, is slenderer and smaller than the female. There is also a great difference in colour between them. It is difficult, as Mr. Lloyd (15. 'Game Birds of Sweden,' etc., 1867, p. 466.) remarks, "for any one, who has not seen this fish during the spawning-season, when its hues are brightest, to conceive the admixture of brilliant colours with which it, in other respects so ill-favoured, is at that time adorned." Both sexes of the Labrus mixtus, although very different in colour, are beautiful; the male being orange with bright blue stripes, and the female bright red with some black spots on the back. [Fig. 30. Xiphophorus Hellerii. Upper figure, male; lower figure, female.] In the very distinct family of the Cyprinodontidae--inhabitants of the fresh waters of foreign lands--the sexes sometimes differ much in various characters. In the male of the Mollienesia petenensis (16. With respect to this and the following species I am indebted to Dr. Gunther for information: see also his paper on the 'Fishes of Central America,' in 'Transact. Zoological Soc.' vol. vi. 1868, p. 485.), the dorsal fin is greatly developed and is marked with a row of large, round, ocellated, bright-coloured spots; whilst the same fin in the female is smaller, of a different shape, and marked only with irregularly curved brown spots. In the male the basal margin of the anal fin is also a little produced and dark coloured. In the male of an allied form, the Xiphophorus Hellerii (Fig. 30), the inferior margin of the caudal fin is developed into a long filament, which, as I hear from Dr. Gunther, is striped with bright colours. This filament does not contain any muscles, and apparently cannot be of any direct use to the fish. As in the case of the Callionymus, the males whilst young resemble the adult females in colour and structure. Sexual differences such as these may be strictly compared with those which are so frequent with gallinaceous birds. (17. Dr. Gunther makes this remark; 'Catalogue of Fishes in the British Museum,' vol. iii. 1861, p. 141.) [Fig.31. Plecostomus barbatus. Upper figure, head of male; lower figure, female.] In a siluroid fish, inhabiting the fresh waters of South America, the Plecostomus barbatus (18. See Dr. Gunther on this genus, in 'Proceedings of the Zoological Society,' 1868, p. 232.) (Fig. 31), the male has its mouth and inter-operculum fringed with a beard of stiff hairs, of which the female shows hardly a trace. These hairs are of the nature of scales. In another species of the same genus, soft flexible tentacles project from the front part of the head of the male, which are absent in the female. These tentacles are prolongations of the true skin, and therefore are not homologous with the stiff hairs of the former species; but it can hardly be doubted that both serve the same purpose. What this purpose may be, it is difficult to conjecture; ornament does not here seem probable, but we can hardly suppose that stiff hairs and flexible filaments can be useful in any ordinary way to the males alone. In that strange monster, the Chimaera monstrosa, the male has a hook-shaped bone on the top of the head, directed forwards, with its end rounded and covered with sharp spines; in the female "this crown is altogether absent," but what its use may be to the male is utterly unknown. (19. F. Buckland, in 'Land and Water,' July 1868, p. 377, with a figure. Many other cases could be added of structures peculiar to the male, of which the uses are not known.) The structures as yet referred to are permanent in the male after he has arrived at maturity; but with some Blennies, and in another allied genus (20. Dr. Gunther, 'Catalogue of Fishes,' vol. iii. pp. 221 and 240.), a crest is developed on the head of the male only during the breeding-season, and the body at the same time becomes more brightly-coloured. There can be little doubt that this crest serves as a temporary sexual ornament, for the female does not exhibit a trace of it. In other species of the same genus both sexes possess a crest, and in at least one species neither sex is thus provided. In many of the Chromidae, for instance in Geophagus and especially in Cichla, the males, as I hear from Professor Agassiz (21. See also 'A Journey in Brazil,' by Prof. and Mrs. Agassiz, 1868, p. 220.), have a conspicuous protuberance on the forehead, which is wholly wanting in the females and in the young males. Professor Agassiz adds, "I have often observed these fishes at the time of spawning when the protuberance is largest, and at other seasons when it is totally wanting, and the two sexes shew no difference whatever in the outline of the profile of the head. I never could ascertain that it subserves any special function, and the Indians on the Amazon know nothing about its use." These protuberances resemble, in their periodical appearance, the fleshy carbuncles on the heads of certain birds; but whether they serve as ornaments must remain at present doubtful. I hear from Professor Agassiz and Dr. Gunther, that the males of those fishes, which differ permanently in colour from the females, often become more brilliant during the breeding-season. This is likewise the case with a multitude of fishes, the sexes of which are identical in colour at all other seasons of the year. The tench, roach, and perch may be given as instances. The male salmon at this season is "marked on the cheeks with orange-coloured stripes, which give it the appearance of a Labrus, and the body partakes of a golden orange tinge. The females are dark in colour, and are commonly called black-fish." (22. Yarrell, 'History of British Fishes,' vol. ii. 1836, pp. 10, 12, 35.) An analogous and even greater change takes place with the Salmo eriox or bull trout; the males of the char (S. umbla) are likewise at this season rather brighter in colour than the females. (23. W. Thompson, in 'Annals and Magazine of Natural History,' vol. vi. 1841, p. 440.) The colours of the pike (Esox reticulatus) of the United States, especially of the male, become, during the breeding-season, exceedingly intense, brilliant, and iridescent. (24. 'The American Agriculturalist,' 1868, p. 100.) Another striking instance out of many is afforded by the male stickleback (Gasterosteus leiurus), which is described by Mr. Warington (25. 'Annals and Mag. of Nat. Hist.' Oct. 1852.), as being then "beautiful beyond description." The back and eyes of the female are simply brown, and the belly white. The eyes of the male, on the other hand, are "of the most splendid green, having a metallic lustre like the green feathers of some humming-birds. The throat and belly are of a bright crimson, the back of an ashy-green, and the whole fish appears as though it were somewhat translucent and glowed with an internal incandescence." After the breeding season these colours all change, the throat and belly become of a paler red, the back more green, and the glowing tints subside. With respect to the courtship of fishes, other cases have been observed since the first edition of this book appeared, besides that already given of the stickleback. Mr. W.S. Kent says that the male of the Labrus mixtus, which, as we have seen, differs in colour from the female, makes "a deep hollow in the sand of the tank, and then endeavours in the most persuasive manner to induce a female of the same species to share it with him, swimming backwards and forwards between her and the completed nest, and plainly exhibiting the greatest anxiety for her to follow." The males of Cantharus lineatus become, during the breeding-season, of deep leaden-black; they then retire from the shoal, and excavate a hollow as a nest. "Each male now mounts vigilant guard over his respective hollow, and vigorously attacks and drives away any other fish of the same sex. Towards his companions of the opposite sex his conduct is far different; many of the latter are now distended with spawn, and these he endeavours by all the means in his power to lure singly to his prepared hollow, and there to deposit the myriad ova with which they are laden, which he then protects and guards with the greatest care." (26. 'Nature,' May 1873, p. 25.) A more striking case of courtship, as well as of display, by the males of a Chinese Macropus has been given by M. Carbonnier, who carefully observed these fishes under confinement. (27. 'Bulletin de la Societé d'Acclimat.' Paris, July 1869, and Jan. 1870.) The males are most beautifully coloured, more so than the females. During the breeding-season they contend for the possession of the females; and, in the act of courtship, expand their fins, which are spotted and ornamented with brightly coloured rays, in the same manner, according to M. Carbonnier, as the peacock. They then also bound about the females with much vivacity, and appear by "l'étalage de leurs vives couleurs chercher a attirer l'attention des femelles, lesquelles ne paraissaient indifférentes a ce manège, elles nageaient avec une molle lenteur vers les males et semblaient se complaire dans leur voisinage." After the male has won his bride, he makes a little disc of froth by blowing air and mucus out of his mouth. He then collects the fertilised ova, dropped by the female, in his mouth; and this caused M. Carbonnier much alarm, as he thought that they were going to be devoured. But the male soon deposits them in the disc of froth, afterwards guarding them, repairing the froth, and taking care of the young when hatched. I mention these particulars because, as we shall presently see, there are fishes, the males of which hatch their eggs in their mouths; and those who do not believe in the principle of gradual evolution might ask how could such a habit have originated; but the difficulty is much diminished when we know that there are fishes which thus collect and carry the eggs; for if delayed by any cause in depositing them, the habit of hatching them in their mouths might have been acquired. To return to our more immediate subject. The case stands thus: female fishes, as far as I can learn, never willingly spawn except in the presence of the males; and the males never fertilise the ova except in the presence of the females. The males fight for the possession of the females. In many species, the males whilst young resemble the females in colour; but when adult become much more brilliant, and retain their colours throughout life. In other species the males become brighter than the females and otherwise more highly ornamented, only during the season of love. The males sedulously court the females, and in one case, as we have seen, take pains in displaying their beauty before them. Can it be believed that they would thus act to no purpose during their courtship? And this would be the case, unless the females exert some choice and select those males which please or excite them most. If the female exerts such choice, all the above facts on the ornamentation of the males become at once intelligible by the aid of sexual selection. We have next to inquire whether this view of the bright colours of certain male fishes having been acquired through sexual selection can, through the law of the equal transmission of characters to both sexes, be extended to those groups in which the males and females are brilliant in the same, or nearly the same degree and manner. In such a genus as Labrus, which includes some of the most splendid fishes in the world--for instance, the Peacock Labrus (L. pavo), described (28. Bory Saint Vincent, in 'Dict. Class. d'Hist. Nat.' tom. ix. 1826, p. 151.), with pardonable exaggeration, as formed of polished scales of gold, encrusting lapis-lazuli, rubies, sapphires, emeralds, and amethysts--we may, with much probability, accept this belief; for we have seen that the sexes in at least one species of the genus differ greatly in colour. With some fishes, as with many of the lowest animals, splendid colours may be the direct result of the nature of their tissues and of the surrounding conditions, without the aid of selection of any kind. The gold-fish (Cyprinus auratus), judging from the analogy of the golden variety of the common carp, is perhaps a case in point, as it may owe its splendid colours to a single abrupt variation, due to the conditions to which this fish has been subjected under confinement. It is, however, more probable that these colours have been intensified through artificial selection, as this species has been carefully bred in China from a remote period. (29. Owing to some remarks on this subject, made in my work 'On the Variation of Animals under Domestication,' Mr. W.F. Mayers ('Chinese Notes and Queries,' Aug. 1868, p. 123) has searched the ancient Chinese encyclopedias. He finds that gold-fish were first reared in confinement during the Sung Dynasty, which commenced A.D. 960. In the year 1129 these fishes abounded. In another place it is said that since the year 1548 there has been "produced at Hangchow a variety called the fire-fish, from its intensely red colour. It is universally admired, and there is not a household where it is not cultivated, IN RIVALRY AS TO ITS COLOUR, and as a source of profit.") Under natural conditions it does not seem probable that beings so highly organised as fishes, and which live under such complex relations, should become brilliantly coloured without suffering some evil or receiving some benefit from so great a change, and consequently without the intervention of natural selection. What, then, are we to conclude in regard to the many fishes, both sexes of which are splendidly coloured? Mr. Wallace (30. 'Westminster Review,' July 1867, p. 7.) believes that the species which frequent reefs, where corals and other brightly-coloured organisms abound, are brightly coloured in order to escape detection by their enemies; but according to my recollection they were thus rendered highly conspicuous. In the fresh-waters of the tropics there are no brilliantly-coloured corals or other organisms for the fishes to resemble; yet many species in the Amazons are beautifully coloured, and many of the carnivorous Cyprinidae in India are ornamented with "bright longitudinal lines of various tints." (31. 'Indian Cyprinidae,' by Mr. M'Clelland, 'Asiatic Researches,' vol. xix. part ii. 1839, p. 230.) Mr. M'Clelland, in describing these fishes, goes so far as to suppose that "the peculiar brilliancy of their colours" serves as "a better mark for king-fishers, terns, and other birds which are destined to keep the number of these fishes in check"; but at the present day few naturalists will admit that any animal has been made conspicuous as an aid to its own destruction. It is possible that certain fishes may have been rendered conspicuous in order to warn birds and beasts of prey that they were unpalatable, as explained when treating of caterpillars; but it is not, I believe, known that any fish, at least any fresh-water fish, is rejected from being distasteful to fish-devouring animals. On the whole, the most probable view in regard to the fishes, of which both sexes are brilliantly coloured, is that their colours were acquired by the males as a sexual ornament, and were transferred equally, or nearly so, to the other sex. We have now to consider whether, when the male differs in a marked manner from the female in colour or in other ornaments, he alone has been modified, the variations being inherited by his male offspring alone; or whether the female has been specially modified and rendered inconspicuous for the sake of protection, such modifications being inherited only by the females. It is impossible to doubt that colour has been gained by many fishes as a protection: no one can examine the speckled upper surface of a flounder, and overlook its resemblance to the sandy bed of the sea on which it lives. Certain fishes, moreover, can through the action of the nervous system change their colours in adaptation to surrounding objects, and that within a short time. (32. G. Pouchet, 'L'Institut.' Nov. 1, 1871, p. 134.) One of the most striking instances ever recorded of an animal being protected by its colour (as far as it can be judged of in preserved specimens), as well as by its form, is that given by Dr. Gunther (33. 'Proc. Zoolog. Soc.' 1865, p. 327, pl. xiv. and xv.) of a pipe-fish, which, with its reddish streaming filaments, is hardly distinguishable from the sea-weed to which it clings with its prehensile tail. But the question now under consideration is whether the females alone have been modified for this object. We can see that one sex will not be modified through natural selection for the sake of protection more than the other, supposing both to vary, unless one sex is exposed for a longer period to danger, or has less power of escaping from such danger than the other; and it does not appear that with fishes the sexes differ in these respects. As far as there is any difference, the males, from being generally smaller and from wandering more about, are exposed to greater danger than the females; and yet, when the sexes differ, the males are almost always the more conspicuously coloured. The ova are fertilised immediately after being deposited; and when this process lasts for several days, as in the case of the salmon (34. Yarrell, 'British Fishes,' vol. ii. p. 11.), the female, during the whole time, is attended by the male. After the ova are fertilised they are, in most cases, left unprotected by both parents, so that the males and females, as far as oviposition is concerned, are equally exposed to danger, and both are equally important for the production of fertile ova; consequently the more or less brightly-coloured individuals of either sex would be equally liable to be destroyed or preserved, and both would have an equal influence on the colours of their offspring. Certain fishes, belonging to several families, make nests, and some of them take care of their young when hatched. Both sexes of the bright coloured Crenilabrus massa and melops work together in building their nests with sea-weed, shells, etc. (35. According to the observations of M. Gerbe; see Gunther's 'Record of Zoolog. Literature,' 1865, p. 194.) But the males of certain fishes do all the work, and afterwards take exclusive charge of the young. This is the case with the dull-coloured gobies (36. Cuvier, 'Regne Animal,' vol. ii. 1829, p. 242.), in which the sexes are not known to differ in colour, and likewise with the sticklebacks (Gasterosteus), in which the males become brilliantly coloured during the spawning season. The male of the smooth-tailed stickleback (G. leiurus) performs the duties of a nurse with exemplary care and vigilance during a long time, and is continually employed in gently leading back the young to the nest, when they stray too far. He courageously drives away all enemies including the females of his own species. It would indeed be no small relief to the male, if the female, after depositing her eggs, were immediately devoured by some enemy, for he is forced incessantly to drive her from the nest. (37. See Mr. Warington's most interesting description of the habits of the Gasterosteus leiurus in 'Annals and Magazine of Nat. History,' November 1855.) The males of certain other fishes inhabiting South America and Ceylon, belonging to two distinct Orders, have the extraordinary habit of hatching within their mouths, or branchial cavities, the eggs laid by the females. (38. Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.' Sept. 15, 1857. Also Prof. Turner, in 'Journal of Anatomy and Physiology,' Nov. 1, 1866, p. 78. Dr. Gunther has likewise described other cases.) I am informed by Professor Agassiz that the males of the Amazonian species which follow this habit, "not only are generally brighter than the females, but the difference is greater at the spawning-season than at any other time." The species of Geophagus act in the same manner; and in this genus, a conspicuous protuberance becomes developed on the forehead of the males during the breeding-season. With the various species of Chromids, as Professor Agassiz likewise informs me, sexual differences in colour may be observed, "whether they lay their eggs in the water among aquatic plants, or deposit them in holes, leaving them to come out without further care, or build shallow nests in the river mud, over which they sit, as our Pomotis does. It ought also to be observed that these sitters are among the brightest species in their respective families; for instance, Hygrogonus is bright green, with large black ocelli, encircled with the most brilliant red." Whether with all the species of Chromids it is the male alone which sits on the eggs is not known. It is, however, manifest that the fact of the eggs being protected or unprotected by the parents, has had little or no influence on the differences in colour between the sexes. It is further manifest, in all the cases in which the males take exclusive charge of the nests and young, that the destruction of the brighter-coloured males would be far more influential on the character of the race, than the destruction of the brighter-coloured females; for the death of the male during the period of incubation or nursing would entail the death of the young, so that they could not inherit his peculiarities; yet, in many of these very cases the males are more conspicuously coloured than the females. In most of the Lophobranchii (Pipe-fish, Hippocampi, etc.) the males have either marsupial sacks or hemispherical depressions on the abdomen, in which the ova laid by the female are hatched. The males also shew great attachment to their young. (39. Yarrell, 'History of British Fishes,' vol. ii. 1836, pp. 329, 338.) The sexes do not commonly differ much in colour; but Dr. Gunther believes that the male Hippocampi are rather brighter than the females. The genus Solenostoma, however, offers a curious exceptional case (40. Dr. Gunther, since publishing an account of this species in 'The Fishes of Zanzibar,' by Col. Playfair, 1866, p. 137, has re-examined the specimens, and has given me the above information.), for the female is much more vividly-coloured and spotted than the male, and she alone has a marsupial sack and hatches the eggs; so that the female of Solenostoma differs from all the other Lophobranchii in this latter respect, and from almost all other fishes, in being more brightly-coloured than the male. It is improbable that this remarkable double inversion of character in the female should be an accidental coincidence. As the males of several fishes, which take exclusive charge of the eggs and young, are more brightly coloured than the females, and as here the female Solenostoma takes the same charge and is brighter than the male, it might be argued that the conspicuous colours of that sex which is the more important of the two for the welfare of the offspring, must be in some manner protective. But from the large number of fishes, of which the males are either permanently or periodically brighter than the females, but whose life is not at all more important for the welfare of the species than that of the female, this view can hardly be maintained. When we treat of birds we shall meet with analogous cases, where there has been a complete inversion of the usual attributes of the two sexes, and we shall then give what appears to be the probable explanation, namely, that the males have selected the more attractive females, instead of the latter having selected, in accordance with the usual rule throughout the animal kingdom, the more attractive males. On the whole we may conclude, that with most fishes, in which the sexes differ in colour or in other ornamental characters, the males originally varied, with their variations transmitted to the same sex, and accumulated through sexual selection by attracting or exciting the females. In many cases, however, such characters have been transferred, either partially or completely, to the females. In other cases, again, both sexes have been coloured alike for the sake of protection; but in no instance does it appear that the female alone has had her colours or other characters specially modified for this latter purpose. The last point which need be noticed is that fishes are known to make various noises, some of which are described as being musical. Dr. Dufosse, who has especially attended to this subject, says that the sounds are voluntarily produced in several ways by different fishes: by the friction of the pharyngeal bones--by the vibration of certain muscles attached to the swim bladder, which serves as a resounding board--and by the vibration of the intrinsic muscles of the swim bladder. By this latter means the Trigla produces pure and long-drawn sounds which range over nearly an octave. But the most interesting case for us is that of two species of Ophidium, in which the males alone are provided with a sound-producing apparatus, consisting of small movable bones, with proper muscles, in connection with the swim bladder. (41. 'Comptes-Rendus,' tom. xlvi. 1858, p. 353; tom. xlvii. 1858, p. 916; tom. liv. 1862, p. 393. The noise made by the Umbrinas (Sciaena aquila), is said by some authors to be more like that of a flute or organ, than drumming: Dr. Zouteveen, in the Dutch translation of this work (vol. ii. p. 36), gives some further particulars on the sounds made by fishes.) The drumming of the Umbrinas in the European seas is said to be audible from a depth of twenty fathoms; and the fishermen of Rochelle assert "that the males alone make the noise during the spawning-time; and that it is possible by imitating it, to take them without bait." (42. The Rev. C. Kingsley, in 'Nature,' May 1870, p. 40.) From this statement, and more especially from the case of Ophidium, it is almost certain that in this, the lowest class of the Vertebrata, as with so many insects and spiders, sound-producing instruments have, at least in some cases, been developed through sexual selection, as a means for bringing the sexes together. AMPHIBIANS. URODELA. [Fig. 32. Triton cristatus (half natural size, from Bell's 'British Reptiles'). Upper figure, male during the breeding season; lower figure, female.] I will begin with the tailed amphibians. The sexes of salamanders or newts often differ much both in colour and structure. In some species prehensile claws are developed on the fore-legs of the males during the breeding-season: and at this season in the male Triton palmipes the hind-feet are provided with a swimming-web, which is almost completely absorbed during the winter; so that their feet then resemble those of the female. (43. Bell, 'History of British Reptiles,' 2nd ed., 1849, pp. 156-159.) This structure no doubt aids the male in his eager search and pursuit of the female. Whilst courting her he rapidly vibrates the end of his tail. With our common newts (Triton punctatus and cristatus) a deep, much indented crest is developed along the back and tail of the male during the breeding-season, which disappears during the winter. Mr. St. George Mivart informs me that it is not furnished with muscles, and therefore cannot be used for locomotion. As during the season of courtship it becomes edged with bright colours, there can hardly be a doubt that it is a masculine ornament. In many species the body presents strongly contrasted, though lurid tints, and these become more vivid during the breeding-season. The male, for instance, of our common little newt (Triton punctatus) is "brownish-grey above, passing into yellow beneath, which in the spring becomes a rich bright orange, marked everywhere with round dark spots." The edge of the crest also is then tipped with bright red or violet. The female is usually of a yellowish-brown colour with scattered brown dots, and the lower surface is often quite plain. (44. Bell, 'History of British Reptiles,' 2nd ed., 1849, pp. 146, 151.) The young are obscurely tinted. The ova are fertilised during the act of deposition, and are not subsequently tended by either parent. We may therefore conclude that the males have acquired their strongly-marked colours and ornamental appendages through sexual selection; these being transmitted either to the male offspring alone, or to both sexes. ANURA OR BATRACHIA. With many frogs and toads the colours evidently serve as a protection, such as the bright green tints of tree frogs and the obscure mottled shades of many terrestrial species. The most conspicuously-coloured toad which I ever saw, the Phryniscus nigricans (45. 'Zoology of the Voyage of the "Beagle,"' 1843. Bell, ibid. p. 49.), had the whole upper surface of the body as black as ink, with the soles of the feet and parts of the abdomen spotted with the brightest vermilion. It crawled about the bare sandy or open grassy plains of La Plata under a scorching sun, and could not fail to catch the eye of every passing creature. These colours are probably beneficial by making this animal known to all birds of prey as a nauseous mouthful. In Nicaragua there is a little frog "dressed in a bright livery of red and blue" which does not conceal itself like most other species, but hops about during the daytime, and Mr. Belt says (46. 'The Naturalist in Nicaragua,' 1874, p. 321.) that as soon as he saw its happy sense of security, he felt sure that it was uneatable. After several trials he succeeded in tempting a young duck to snatch up a young one, but it was instantly rejected; and the duck "went about jerking its head, as if trying to throw off some unpleasant taste." With respect to sexual differences of colour, Dr. Gunther does not know of any striking instance either with frogs or toads; yet he can often distinguish the male from the female by the tints of the former being a little more intense. Nor does he know of any striking difference in external structure between the sexes, excepting the prominences which become developed during the breeding-season on the front legs of the male, by which he is enabled to hold the female. (47. The male alone of the Bufo sikimmensis (Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 204) has two plate-like callosities on the thorax and certain rugosities on the fingers, which perhaps subserve the same end as the above-mentioned prominences.) It is surprising that these animals have not acquired more strongly-marked sexual characters; for though cold-blooded their passions are strong. Dr. Gunther informs me that he has several times found an unfortunate female toad dead and smothered from having been so closely embraced by three or four males. Frogs have been observed by Professor Hoffman in Giessen fighting all day long during the breeding-season, and with so much violence that one had its body ripped open. Frogs and toads offer one interesting sexual difference, namely, in the musical powers possessed by the males; but to speak of music, when applied to the discordant and overwhelming sounds emitted by male bull-frogs and some other species, seems, according to our taste, a singularly inappropriate expression. Nevertheless, certain frogs sing in a decidedly pleasing manner. Near Rio Janeiro I used often to sit in the evening to listen to a number of little Hylae, perched on blades of grass close to the water, which sent forth sweet chirping notes in harmony. The various sounds are emitted chiefly by the males during the breeding-season, as in the case of the croaking of our common frog. (48. Bell, 'History British Reptiles,' 1849, p. 93.) In accordance with this fact the vocal organs of the males are more highly-developed than those of the females. In some genera the males alone are provided with sacs which open into the larynx. (49. J. Bishop, in 'Todd's Cyclopaedia of Anatomy and Physiology,' vol. iv. p. 1503.) For instance, in the edible frog (Rana esculenta) "the sacs are peculiar to the males, and become, when filled with air in the act of croaking, large globular bladders, standing out one on each side of the head, near the corners of the mouth." The croak of the male is thus rendered exceedingly powerful; whilst that of the female is only a slight groaning noise. (50. Bell, ibid. pp. 112-114.) In the several genera of the family the vocal organs differ considerably in structure, and their development in all cases may be attributed to sexual selection. REPTILES. CHELONIA. Tortoises and turtles do not offer well-marked sexual differences. In some species, the tail of the male is longer than that of the female. In some, the plastron or lower surface of the shell of the male is slightly concave in relation to the back of the female. The male of the mud-turtle of the United States (Chrysemys picta) has claws on its front feet twice as long as those of the female; and these are used when the sexes unite. (51. Mr. C.J. Maynard, 'The American Naturalist,' Dec. 1869, p. 555.) With the huge tortoise of the Galapagos Islands (Testudo nigra) the males are said to grow to a larger size than the females: during the pairing-season, and at no other time, the male utters a hoarse bellowing noise, which can be heard at the distance of more than a hundred yards; the female, on the other hand, never uses her voice. (52. See my 'Journal of Researches during the Voyage of the "Beagle,"' 1845, p. 384.) With the Testudo elegans of India, it is said "that the combats of the males may be heard at some distance, from the noise they produce in butting against each other." (53. Dr. Gunther, 'Reptiles of British India,' 1864, p. 7.) CROCODILIA. The sexes apparently do not differ in colour; nor do I know that the males fight together, though this is probable, for some kinds make a prodigious display before the females. Bartram (54. 'Travels through Carolina,' etc., 1791, p. 128.) describes the male alligator as striving to win the female by splashing and roaring in the midst of a lagoon, "swollen to an extent ready to burst, with its head and tail lifted up, he springs or twirls round on the surface of the water, like an Indian chief rehearsing his feats of war." During the season of love, a musky odour is emitted by the submaxillary glands of the crocodile, and pervades their haunts. (55. Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.) OPHIDIA. Dr. Gunther informs me that the males are always smaller than the females, and generally have longer and slenderer tails; but he knows of no other difference in external structure. In regard to colour, be can almost always distinguish the male from the female, by his more strongly-pronounced tints; thus the black zigzag band on the back of the male English viper is more distinctly defined than in the female. The difference is much plainer in the rattle-snakes of N. America, the male of which, as the keeper in the Zoological Gardens shewed me, can at once be distinguished from the female by having more lurid yellow about its whole body. In S. Africa the Bucephalus capensis presents an analogous difference, for the female "is never so fully variegated with yellow on the sides as the male." (56. Sir Andrew Smith, 'Zoology of S. Africa: Reptilia,' 1849, pl. x.) The male of the Indian Dipsas cynodon, on the other hand, is blackish-brown, with the belly partly black, whilst the female is reddish or yellowish-olive, with the belly either uniform yellowish or marbled with black. In the Tragops dispar of the same country the male is bright green, and the female bronze-coloured. (57. Dr. A. Gunther, 'Reptiles of British India,' Ray Soc., 1864, pp. 304, 308.) No doubt the colours of some snakes are protective, as shewn by the green tints of tree-snakes, and the various mottled shades of the species which live in sandy places; but it is doubtful whether the colours of many kinds, for instance of the common English snake and viper, serve to conceal them; and this is still more doubtful with the many foreign species which are coloured with extreme elegance. The colours of certain species are very different in the adult and young states. (58. Dr. Stoliczka, 'Journal of Asiatic Society of Bengal,' vol. xxxix, 1870, pp. 205, 211.) During the breeding-season the anal scent-glands of snakes are in active function (59. Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.); and so it is with the same glands in lizards, and as we have seen with the submaxillary glands of crocodiles. As the males of most animals search for the females, these odoriferous glands probably serve to excite or charm the female, rather than to guide her to the spot where the male may be found. Male snakes, though appearing so sluggish, are amorous; for many have been observed crowding round the same female, and even round her dead body. They are not known to fight together from rivalry. Their intellectual powers are higher than might have been anticipated. In the Zoological Gardens they soon learn not to strike at the iron bar with which their cages are cleaned; and Dr. Keen of Philadelphia informs me that some snakes which he kept learned after four or five times to avoid a noose, with which they were at first easily caught. An excellent observer in Ceylon, Mr. E. Layard, saw (60. 'Rambles in Ceylon,' in 'Annals and Magazine of Natural History,' 2nd series, vol. ix. 1852, p. 333.) a cobra thrust its head through a narrow hole and swallow a toad. "With this encumbrance he could not withdraw himself; finding this, he reluctantly disgorged the precious morsel, which began to move off; this was too much for snake philosophy to bear, and the toad was again seized, and again was the snake, after violent efforts to escape, compelled to part with its prey. This time, however, a lesson had been learnt, and the toad was seized by one leg, withdrawn, and then swallowed in triumph." The keeper in the Zoological Gardens is positive that certain snakes, for instance Crotalus and Python, distinguish him from all other persons. Cobras kept together in the same cage apparently feel some attachment towards each other. (61. Dr. Gunther, 'Reptiles of British India,' 1864, p. 340.) It does not, however, follow because snakes have some reasoning power, strong passions and mutual affection, that they should likewise be endowed with sufficient taste to admire brilliant colours in their partners, so as to lead to the adornment of the species through sexual selection. Nevertheless, it is difficult to account in any other manner for the extreme beauty of certain species; for instance, of the coral-snakes of S. America, which are of a rich red with black and yellow transverse bands. I well remember how much surprise I felt at the beauty of the first coral-snake which I saw gliding across a path in Brazil. Snakes coloured in this peculiar manner, as Mr. Wallace states on the authority of Dr. Gunther (62. 'Westminster Review,' July 1st, 1867, p. 32.), are found nowhere else in the world except in S. America, and here no less than four genera occur. One of these, Elaps, is venomous; a second and widely-distinct genus is doubtfully venomous, and the two others are quite harmless. The species belonging to these distinct genera inhabit the same districts, and are so like each other that no one "but a naturalist would distinguish the harmless from the poisonous kinds." Hence, as Mr. Wallace believes, the innocuous kinds have probably acquired their colours as a protection, on the principle of imitation; for they would naturally be thought dangerous by their enemies. The cause, however, of the bright colours of the venomous Elaps remains to be explained, and this may perhaps be sexual selection. Snakes produce other sounds besides hissing. The deadly Echis carinata has on its sides some oblique rows of scales of a peculiar structure with serrated edges; and when this snake is excited these scales are rubbed against each other, which produces "a curious prolonged, almost hissing sound." (63. Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 196.) With respect to the rattling of the rattle-snake, we have at last some definite information: for Professor Aughey states (64. The 'American Naturalist,' 1873, p. 85.), that on two occasions, being himself unseen, he watched from a little distance a rattle-snake coiled up with head erect, which continued to rattle at short intervals for half an hour: and at last he saw another snake approach, and when they met they paired. Hence he is satisfied that one of the uses of the rattle is to bring the sexes together. Unfortunately he did not ascertain whether it was the male or the female which remained stationary and called for the other. But it by no means follows from the above fact that the rattle may not be of use to these snakes in other ways, as a warning to animals which would otherwise attack them. Nor can I quite disbelieve the several accounts which have appeared of their thus paralysing their prey with fear. Some other snakes also make a distinct noise by rapidly vibrating their tails against the surrounding stalks of plants; and I have myself heard this in the case of a Trigonocephalus in S. America. LACERTILIA. The males of some, probably of many kinds of lizards, fight together from rivalry. Thus the arboreal Anolis cristatellus of S. America is extremely pugnacious: "During the spring and early part of the summer, two adult males rarely meet without a contest. On first seeing one another, they nod their heads up and down three or four times, and at the same time expanding the frill or pouch beneath the throat; their eyes glisten with rage, and after waving their tails from side to side for a few seconds, as if to gather energy, they dart at each other furiously, rolling over and over, and holding firmly with their teeth. The conflict generally ends in one of the combatants losing his tail, which is often devoured by the victor." The male of this species is considerably larger than the female (65. Mr. N.L. Austen kept these animals alive for a considerable time; see 'Land and Water,' July 1867, p. 9.); and this, as far as Dr. Gunther has been able to ascertain, is the general rule with lizards of all kinds. The male alone of the Cyrtodactylus rubidus of the Andaman Islands possesses pre-anal pores; and these pores, judging from analogy, probably serve to emit an odour. (66. Stoliczka, 'Journal of the Asiatic Society of Bengal,' vol. xxxiv. 1870, p. 166.) [Fig.33. Sitana minor. Male with the gular pouch expanded (from Gunther's 'Reptiles of India')'] The sexes often differ greatly in various external characters. The male of the above-mentioned Anolis is furnished with a crest which runs along the back and tail, and can be erected at pleasure; but of this crest the female does not exhibit a trace. In the Indian Cophotis ceylanica, the female has a dorsal crest, though much less developed than in the male; and so it is, as Dr. Gunther informs me, with the females of many Iguanas, Chameleons, and other lizards. In some species, however, the crest is equally developed in both sexes, as in the Iguana tuberculata. In the genus Sitana, the males alone are furnished with a large throat pouch (Fig. 33), which can be folded up like a fan, and is coloured blue, black, and red; but these splendid colours are exhibited only during the pairing-season. The female does not possess even a rudiment of this appendage. In the Anolis cristatellus, according to Mr. Austen, the throat pouch, which is bright red marbled with yellow, is present in the female, though in a rudimental condition. Again, in certain other lizards, both sexes are equally well provided with throat pouches. Here we see with species belonging to the same group, as in so many previous cases, the same character either confined to the males, or more largely developed in them than in the females, or again equally developed in both sexes. The little lizards of the genus Draco, which glide through the air on their rib-supported parachutes, and which in the beauty of their colours baffle description, are furnished with skinny appendages to the throat "like the wattles of gallinaceous birds." These become erected when the animal is excited. They occur in both sexes, but are best developed when the male arrives at maturity, at which age the middle appendage is sometimes twice as long as the head. Most of the species likewise have a low crest running along the neck; and this is much more developed in the full-grown males than in the females or young males. (67. All the foregoing statements and quotations, in regard to Cophotis, Sitana and Draco, as well as the following facts in regard to Ceratophora and Chamaeleon, are from Dr. Gunther himself, or from his magnificent work on the 'Reptiles of British India,' Ray Soc., 1864, pp. 122, 130, 135.) A Chinese species is said to live in pairs during the spring; "and if one is caught, the other falls from the tree to the ground, and allows itself to be captured with impunity"--I presume from despair. (68. Mr. Swinhoe, 'Proc. Zoolog. Soc.' 1870, p. 240.) [Fig. 34. Ceratophora Stoddartii. Upper figure; lower figure, female.] There are other and much more remarkable differences between the sexes of certain lizards. The male of Ceratophora aspera bears on the extremity of his snout an appendage half as long as the head. It is cylindrical, covered with scales, flexible, and apparently capable of erection: in the female it is quite rudimental. In a second species of the same genus a terminal scale forms a minute horn on the summit of the flexible appendage; and in a third species (C. Stoddartii, fig. 34) the whole appendage is converted into a horn, which is usually of a white colour, but assumes a purplish tint when the animal is excited. In the adult male of this latter species the horn is half an inch in length, but it is of quite minute size in the female and in the young. These appendages, as Dr. Gunther has remarked to me, may be compared with the combs of gallinaceous birds, and apparently serve as ornaments. [Fig. 35. Chamaeleo bifurcus. Upper figure, male; lower figure, female. Fig. 36. Chamaeleo Owenii. Upper figure, male; lower figure, female.] In the genus Chamaeleon we come to the acme of difference between the sexes. The upper part of the skull of the male C. bifurcus (Fig. 35), an inhabitant of Madagascar, is produced into two great, solid, bony projections, covered with scales like the rest of the head; and of this wonderful modification of structure the female exhibits only a rudiment. Again, in Chamaeleo Owenii (Fig. 36), from the West Coast of Africa, the male bears on his snout and forehead three curious horns, of which the female has not a trace. These horns consist of an excrescence of bone covered with a smooth sheath, forming part of the general integuments of the body, so that they are identical in structure with those of a bull, goat, or other sheath-horned ruminant. Although the three horns differ so much in appearance from the two great prolongations of the skull in C. bifurcus, we can hardly doubt that they serve the same general purpose in the economy of these two animals. The first conjecture, which will occur to every one, is that they are used by the males for fighting together; and as these animals are very quarrelsome (69. Dr. Buchholz, 'Monatsbericht K. Preuss. Akad.' Jan. 1874, p. 78.), this is probably a correct view. Mr. T.W. Wood also informs me that he once watched two individuals of C. pumilus fighting violently on the branch of a tree; they flung their heads about and tried to bite each other; they then rested for a time and afterwards continued their battle. With many lizards the sexes differ slightly in colour, the tints and stripes of the males being brighter and more distinctly defined than in the females. This, for instance, is the case with the above Cophotis and with the Acanthodactylus capensis of S. Africa. In a Cordylus of the latter country, the male is either much redder or greener than the female. In the Indian Calotes nigrilabris there is a still greater difference; the lips also of the male are black, whilst those of the female are green. In our common little viviparous lizard (Zootoca vivipara) "the under side of the body and base of the tail in the male are bright orange, spotted with black; in the female these parts are pale-greyish-green without spots." (70. Bell, 'History of British Reptiles,' 2nd ed., 1849, p. 40.) We have seen that the males alone of Sitana possess a throat-pouch; and this is splendidly tinted with blue, black, and red. In the Proctotretus tenuis of Chile the male alone is marked with spots of blue, green, and coppery-red. (71. For Proctotretus, see 'Zoology of the Voyage of the "Beagle"; Reptiles,' by Mr. Bell, p. 8. For the Lizards of S. Africa, see 'Zoology of S. Africa: Reptiles,' by Sir Andrew Smith, pl. 25 and 39. For the Indian Calotes, see 'Reptiles of British India,' by Dr. Gunther, p. 143.) In many cases the males retain the same colours throughout the year, but in others they become much brighter during the breeding-season; I may give as an additional instance the Calotes maria, which at this season has a bright red head, the rest of the body being green. (72. Gunther in 'Proceedings, Zoological Society,' 1870, p. 778, with a coloured figure.) Both sexes of many species are beautifully coloured exactly alike; and there is no reason to suppose that such colours are protective. No doubt with the bright green kinds which live in the midst of vegetation, this colour serves to conceal them; and in N. Patagonia I saw a lizard (Proctotretus multimaculatus) which, when frightened, flattened its body, closed its eyes, and then from its mottled tints was hardly distinguishable from the surrounding sand. But the bright colours with which so many lizards are ornamented, as well as their various curious appendages, were probably acquired by the males as an attraction, and then transmitted either to their male offspring alone, or to both sexes. Sexual selection, indeed, seems to have played almost as important a part with reptiles as with birds; and the less conspicuous colours of the females in comparison with the males cannot be accounted for, as Mr. Wallace believes to be the case with birds, by the greater exposure of the females to danger during incubation. CHAPTER XIII. SECONDARY SEXUAL CHARACTERS OF BIRDS. Sexual differences--Law of battle--Special weapons--Vocal organs--Instrumental music--Love-antics and dances--Decorations, permanent and seasonal--Double and single annual moults--Display of ornaments by the males. Secondary sexual characters are more diversified and conspicuous in birds, though not perhaps entailing more important changes of structure, than in any other class of animals. I shall, therefore, treat the subject at considerable length. Male birds sometimes, though rarely, possess special weapons for fighting with each other. They charm the female by vocal or instrumental music of the most varied kinds. They are ornamented by all sorts of combs, wattles, protuberances, horns, air-distended sacks, top-knots, naked shafts, plumes and lengthened feathers gracefully springing from all parts of the body. The beak and naked skin about the head, and the feathers, are often gorgeously coloured. The males sometimes pay their court by dancing, or by fantastic antics performed either on the ground or in the air. In one instance, at least, the male emits a musky odour, which we may suppose serves to charm or excite the female; for that excellent observer, Mr. Ramsay (1. 'Ibis,' vol. iii. (new series), 1867, p. 414.), says of the Australian musk-duck (Biziura lobata) that "the smell which the male emits during the summer months is confined to that sex, and in some individuals is retained throughout the year; I have never, even in the breeding-season, shot a female which had any smell of musk." So powerful is this odour during the pairing-season, that it can be detected long before the bird can be seen. (2. Gould, 'Handbook of the Birds of Australia,' 1865, vol. ii. p. 383.) On the whole, birds appear to be the most aesthetic of all animals, excepting of course man, and they have nearly the same taste for the beautiful as we have. This is shewn by our enjoyment of the singing of birds, and by our women, both civilised and savage, decking their heads with borrowed plumes, and using gems which are hardly more brilliantly coloured than the naked skin and wattles of certain birds. In man, however, when cultivated, the sense of beauty is manifestly a far more complex feeling, and is associated with various intellectual ideas. Before treating of the sexual characters with which we are here more particularly concerned, I may just allude to certain differences between the sexes which apparently depend on differences in their habits of life; for such cases, though common in the lower, are rare in the higher classes. Two humming-birds belonging to the genus Eustephanus, which inhabit the island of Juan Fernandez, were long thought to be specifically distinct, but are now known, as Mr. Gould informs me, to be the male and female of the same species, and they differ slightly in the form of the beak. In another genus of humming-birds (Grypus), the beak of the male is serrated along the margin and hooked at the extremity, thus differing much from that of the female. In the Neomorpha of New Zealand, there is, as we have seen, a still wider difference in the form of the beak in relation to the manner of feeding of the two sexes. Something of the same kind has been observed with the goldfinch (Carduelis elegans), for I am assured by Mr. J. Jenner Weir that the bird-catchers can distinguish the males by their slightly longer beaks. The flocks of males are often found feeding on the seeds of the teazle (Dipsacus), which they can reach with their elongated beaks, whilst the females more commonly feed on the seeds of the betony or Scrophularia. With a slight difference of this kind as a foundation, we can see how the beaks of the two sexes might be made to differ greatly through natural selection. In some of the above cases, however, it is possible that the beaks of the males may have been first modified in relation to their contests with other males; and that this afterwards led to slightly changed habits of life. LAW OF BATTLE. Almost all male birds are extremely pugnacious, using their beaks, wings, and legs for fighting together. We see this every spring with our robins and sparrows. The smallest of all birds, namely the humming-bird, is one of the most quarrelsome. Mr. Gosse (3. Quoted by Mr. Gould, 'Introduction to the Trochilidae,' 1861, page 29.) describes a battle in which a pair seized hold of each other's beaks, and whirled round and round, till they almost fell to the ground; and M. Montes de Oca, in speaking or another genus of humming-bird, says that two males rarely meet without a fierce aerial encounter: when kept in cages "their fighting has mostly ended in the splitting of the tongue of one of the two, which then surely dies from being unable to feed." (4. Gould, ibid. p. 52.) With waders, the males of the common water-hen (Gallinula chloropus) "when pairing, fight violently for the females: they stand nearly upright in the water and strike with their feet." Two were seen to be thus engaged for half an hour, until one got hold of the head of the other, which would have been killed had not the observer interfered; the female all the time looking on as a quiet spectator. (5. W. Thompson, 'Natural History of Ireland: Birds,' vol. ii. 1850, p. 327.) Mr. Blyth informs me that the males of an allied bird (Gallicrex cristatus) are a third larger than the females, and are so pugnacious during the breeding-season that they are kept by the natives of Eastern Bengal for the sake of fighting. Various other birds are kept in India for the same purpose, for instance, the bulbuls (Pycnonotus hoemorrhous) which "fight with great spirit." (6. Jerdon, 'Birds of India,' 1863, vol. ii. p. 96.) [Fig. 37. The Ruff or Machetes pugnax (from Brehm's 'Thierleben').] The polygamous ruff (Machetes pugnax, Fig. 37) is notorious for his extreme pugnacity; and in the spring, the males, which are considerably larger than the females, congregate day after day at a particular spot, where the females propose to lay their eggs. The fowlers discover these spots by the turf being trampled somewhat bare. Here they fight very much like game-cocks, seizing each other with their beaks and striking with their wings. The great ruff of feathers round the neck is then erected, and according to Col. Montagu "sweeps the ground as a shield to defend the more tender parts"; and this is the only instance known to me in the case of birds of any structure serving as a shield. The ruff of feathers, however, from its varied and rich colours probably serves in chief part as an ornament. Like most pugnacious birds, they seem always ready to fight, and when closely confined, often kill each other; but Montagu observed that their pugnacity becomes greater during the spring, when the long feathers on their necks are fully developed; and at this period the least movement by any one bird provokes a general battle. (7. Macgillivray, 'History of British Birds,' vol. iv. 1852, pp. 177-181.) Of the pugnacity of web-footed birds, two instances will suffice: in Guiana "bloody fights occur during the breeding-season between the males of the wild musk-duck (Cairina moschata); and where these fights have occurred the river is covered for some distance with feathers." (8. Sir R. Schomburgk, in 'Journal of Royal Geographic Society,' vol. xiii. 1843, p. 31.) Birds which seem ill-adapted for fighting engage in fierce conflicts; thus the stronger males of the pelican drive away the weaker ones, snapping with their huge beaks and giving heavy blows with their wings. Male snipe fight together, "tugging and pushing each other with their bills in the most curious manner imaginable." Some few birds are believed never to fight; this is the case, according to Audubon, with one of the woodpeckers of the United States (Picu sauratus), although "the hens are followed by even half a dozen of their gay suitors." (9. 'Ornithological Biography,' vol. i. p. 191. For pelicans and snipes, see vol. iii. pp. 138, 477.) The males of many birds are larger than the females, and this no doubt is the result of the advantage gained by the larger and stronger males over their rivals during many generations. The difference in size between the two sexes is carried to an extreme point in several Australian species; thus the male musk-duck (Biziura), and the male Cincloramphus cruralis (allied to our pipits) are by measurement actually twice as large as their respective females. (10. Gould, 'Handbook of Birds of Australia,' vol. i. p. 395; vol. ii. p. 383.) With many other birds the females are larger than the males; and, as formerly remarked, the explanation often given, namely, that the females have most of the work in feeding their young, will not suffice. In some few cases, as we shall hereafter see, the females apparently have acquired their greater size and strength for the sake of conquering other females and obtaining possession of the males. The males of many gallinaceous birds, especially of the polygamous kinds, are furnished with special weapons for fighting with their rivals, namely spurs, which can be used with fearful effect. It has been recorded by a trustworthy writer (11. Mr. Hewitt, in the 'Poultry Book' by Tegetmeier, 1866, p. 137.) that in Derbyshire a kite struck at a game-hen accompanied by her chickens, when the cock rushed to the rescue, and drove his spur right through the eye and skull of the aggressor. The spur was with difficulty drawn from the skull, and as the kite, though dead, retained his grasp, the two birds were firmly locked together; but the cock when disentangled was very little injured. The invincible courage of the game-cock is notorious: a gentleman who long ago witnessed the brutal scene, told me that a bird had both its legs broken by some accident in the cockpit, and the owner laid a wager that if the legs could be spliced so that the bird could stand upright, he would continue fighting. This was effected on the spot, and the bird fought with undaunted courage until he received his death-stroke. In Ceylon a closely allied, wild species, the Gallus Stanleyi, is known to fight desperately "in defence of his seraglio," so that one of the combatants is frequently found dead. (12. Layard, 'Annals and Magazine of Natural History,' vol. xiv. 1854, p. 63.) An Indian partridge (Ortygornis gularis), the male of which is furnished with strong and sharp spurs, is so quarrelsome "that the scars of former fights disfigure the breast of almost every bird you kill." (13. Jerdon, 'Birds of India,' vol. iii. p. 574.) The males of almost all gallinaceous birds, even those which are not furnished with spurs, engage during the breeding-season in fierce conflicts. The Capercailzie and Black-cock (Tetrao urogallus and T. tetrix), which are both polygamists, have regular appointed places, where during many weeks they congregate in numbers to fight together and to display their charms before the females. Dr. W. Kovalevsky informs me that in Russia he has seen the snow all bloody on the arenas where the capercailzie have fought; and the black-cocks "make the feathers fly in every direction," when several "engage in a battle royal." The elder Brehm gives a curious account of the Balz, as the love-dances and love-songs of the Black-cock are called in Germany. The bird utters almost continuously the strangest noises: "he holds his tail up and spreads it out like a fan, he lifts up his head and neck with all the feathers erect, and stretches his wings from the body. Then he takes a few jumps in different directions, sometimes in a circle, and presses the under part of his beak so hard against the ground that the chin feathers are rubbed off. During these movements he beats his wings and turns round and round. The more ardent he grows the more lively he becomes, until at last the bird appears like a frantic creature." At such times the black-cocks are so absorbed that they become almost blind and deaf, but less so than the capercailzie: hence bird after bird may be shot on the same spot, or even caught by the hand. After performing these antics the males begin to fight: and the same black-cock, in order to prove his strength over several antagonists, will visit in the course of one morning several Balz-places, which remain the same during successive years. (14. Brehm, 'Thierleben,' 1867, B. iv. s. 351. Some of the foregoing statements are taken from L. Lloyd, 'The Game Birds of Sweden,' etc., 1867, p. 79.) The peacock with his long train appears more like a dandy than a warrior, but he sometimes engages in fierce contests: the Rev. W. Darwin Fox informs me that at some little distance from Chester two peacocks became so excited whilst fighting, that they flew over the whole city, still engaged, until they alighted on the top of St. John's tower. The spur, in those gallinaceous birds which are thus provided, is generally single; but Polyplectron (Fig. 51) has two or more on each leg; and one of the Blood-pheasants (Ithaginis cruentus) has been seen with five spurs. The spurs are generally confined to the male, being represented by mere knobs or rudiments in the female; but the females of the Java peacock (Pavo muticus) and, as I am informed by Mr. Blyth, of the small fire-backed pheasant (Euplocamus erythrophthalmus) possess spurs. In Galloperdix it is usual for the males to have two spurs, and for the females to have only one on each leg. (15. Jerdon, 'Birds of India': on Ithaginis, vol. iii. p. 523; on Galloperdix, p. 541.) Hence spurs may be considered as a masculine structure, which has been occasionally more or less transferred to the females. Like most other secondary sexual characters, the spurs are highly variable, both in number and development, in the same species. [Fig.38. Palamedea cornuta (from Brehm), shewing the double wing-spurs, and the filament on the head.] Various birds have spurs on their wings. But the Egyptian goose (Chenalopex aegyptiacus) has only "bare obtuse knobs," and these probably shew us the first steps by which true spurs have been developed in other species. In the spur-winged goose, Plectropterus gambensis, the males have much larger spurs than the females; and they use them, as I am informed by Mr. Bartlett, in fighting together, so that, in this case, the wing-spurs serve as sexual weapons; but according to Livingstone, they are chiefly used in the defence of the young. The Palamedea (Fig. 38) is armed with a pair of spurs on each wing; and these are such formidable weapons that a single blow has been known to drive a dog howling away. But it does not appear that the spurs in this case, or in that of some of the spur-winged rails, are larger in the male than in the female. (16. For the Egyptian goose, see Macgillivray, 'British Birds,' vol. iv. p. 639. For Plectropterus, Livingstone's 'Travels,' p. 254. For Palamedea, Brehm's 'Thierleben,' B. iv. s. 740. See also on this bird Azara, 'Voyages dans l'Amerique merid.' tom. iv. 1809, pp. 179, 253.) In certain plovers, however, the wing-spurs must be considered as a sexual character. Thus in the male of our common peewit (Vanellus cristatus) the tubercle on the shoulder of the wing becomes more prominent during the breeding-season, and the males fight together. In some species of Lobivanellus a similar tubercle becomes developed during the breeding-season "into a short horny spur." In the Australian L. lobatus both sexes have spurs, but these are much larger in the males than in the females. In an allied bird, the Hoplopterus armatus, the spurs do not increase in size during the breeding-season; but these birds have been seen in Egypt to fight together, in the same manner as our peewits, by turning suddenly in the air and striking sideways at each other, sometimes with fatal results. Thus also they drive away other enemies. (17. See, on our peewit, Mr. R. Carr in 'Land and Water,' Aug. 8th, 1868, p. 46. In regard to Lobivanellus, see Jerdon's 'Birds of India,' vol. iii. p. 647, and Gould's 'Handbook of Birds of Australia,' vol. ii. p. 220. For the Hoplopterus, see Mr. Allen in the 'Ibis,' vol. v. 1863, p. 156.) The season of love is that of battle; but the males of some birds, as of the game-fowl and ruff, and even the young males of the wild turkey and grouse (18. Audubon, 'Ornithological Biography,' vol. ii. p. 492; vol. i. pp. 4-13.), are ready to fight whenever they meet. The presence of the female is the teterrima belli causa. The Bengali baboos make the pretty little males of the amadavat (Estrelda amandava) fight together by placing three small cages in a row, with a female in the middle; after a little time the two males are turned loose, and immediately a desperate battle ensues. (19. Mr. Blyth, 'Land and Water,' 1867, p. 212.) When many males congregate at the same appointed spot and fight together, as in the case of grouse and various other birds, they are generally attended by the females (20. Richardson on Tetrao umbellus, 'Fauna Bor. Amer.: Birds,' 1831, p. 343. L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 22, 79, on the capercailzie and black-cock. Brehm, however, asserts ('Thierleben,' B. iv. s. 352) that in Germany the grey-hens do not generally attend the Balzen of the black-cocks, but this is an exception to the common rule; possibly the hens may lie hidden in the surrounding bushes, as is known to be the case with the gray-hens in Scandinavia, and with other species in N. America.), which afterwards pair with the victorious combatants. But in some cases the pairing precedes instead of succeeding the combat: thus according to Audubon (21. 'Ornithological Biography,' vol. ii. p. 275.), several males of the Virginian goat-sucker (Caprimulgus virgianus) "court, in a highly entertaining manner the female, and no sooner has she made her choice, than her approved gives chase to all intruders, and drives them beyond his dominions." Generally the males try to drive away or kill their rivals before they pair. It does not, however, appear that the females invariably prefer the victorious males. I have indeed been assured by Dr. W. Kovalevsky that the female capercailzie sometimes steals away with a young male who has not dared to enter the arena with the older cocks, in the same manner as occasionally happens with the does of the red-deer in Scotland. When two males contend in presence of a single female, the victor, no doubt, commonly gains his desire; but some of these battles are caused by wandering males trying to distract the peace of an already mated pair. (22. Brehm, 'Thierleben,' etc., B. iv. 1867, p. 990. Audubon, 'Ornithological Biography,' vol. ii. p. 492.) Even with the most pugnacious species it is probable that the pairing does not depend exclusively on the mere strength and courage of the male; for such males are generally decorated with various ornaments, which often become more brilliant during the breeding-season, and which are sedulously displayed before the females. The males also endeavour to charm or excite their mates by love-notes, songs, and antics; and the courtship is, in many instances, a prolonged affair. Hence it is not probable that the females are indifferent to the charms of the opposite sex, or that they are invariably compelled to yield to the victorious males. It is more probable that the females are excited, either before or after the conflict, by certain males, and thus unconsciously prefer them. In the case of Tetrao umbellus, a good observer (23. 'Land and Water,' July 25, 1868, p. 14.) goes so far as to believe that the battles of the male "are all a sham, performed to show themselves to the greatest advantage before the admiring females who assemble around; for I have never been able to find a maimed hero, and seldom more than a broken feather." I shall have to recur to this subject, but I may here add that with the Tetrao cupido of the United States, about a score of males assemble at a particular spot, and, strutting about, make the whole air resound with their extraordinary noises. At the first answer from a female the males begin to fight furiously, and the weaker give way; but then, according to Audubon, both the victors and vanquished search for the female, so that the females must either then exert a choice, or the battle must be renewed. So, again, with one of the field-starlings of the United States (Sturnella ludoviciana) the males engage in fierce conflicts, "but at the sight of a female they all fly after her as if mad." (24. Audubon's 'Ornithological Biography;' on Tetrao cupido, vol. ii. p. 492; on the Sturnus, vol. ii. p. 219.) VOCAL AND INSTRUMENTAL MUSIC. With birds the voice serves to express various emotions, such as distress, fear, anger, triumph, or mere happiness. It is apparently sometimes used to excite terror, as in the case of the hissing noise made by some nestling-birds. Audubon (25. 'Ornithological Biography,' vol. v. p. 601.), relates that a night-heron (Ardea nycticorax, Linn.), which he kept tame, used to hide itself when a cat approached, and then "suddenly start up uttering one of the most frightful cries, apparently enjoying the cat's alarm and flight." The common domestic cock clucks to the hen, and the hen to her chickens, when a dainty morsel is found. The hen, when she has laid an egg, "repeats the same note very often, and concludes with the sixth above, which she holds for a longer time" (26. The Hon. Daines Barrington, 'Philosophical Transactions,' 1773, p. 252.); and thus she expresses her joy. Some social birds apparently call to each other for aid; and as they flit from tree to tree, the flock is kept together by chirp answering chirp. During the nocturnal migrations of geese and other water-fowl, sonorous clangs from the van may be heard in the darkness overhead, answered by clangs in the rear. Certain cries serve as danger signals, which, as the sportsman knows to his cost, are understood by the same species and by others. The domestic cock crows, and the humming-bird chirps, in triumph over a defeated rival. The true song, however, of most birds and various strange cries are chiefly uttered during the breeding-season, and serve as a charm, or merely as a call-note, to the other sex. Naturalists are much divided with respect to the object of the singing of birds. Few more careful observers ever lived than Montagu, and he maintained that the "males of song-birds and of many others do not in general search for the female, but, on the contrary, their business in the spring is to perch on some conspicuous spot, breathing out their full and amorous notes, which, by instinct, the female knows, and repairs to the spot to choose her mate." (27. 'Ornithological Dictionary,' 1833, p. 475.) Mr. Jenner Weir informs me that this is certainly the case with the nightingale. Bechstein, who kept birds during his whole life, asserts, "that the female canary always chooses the best singer, and that in a state of nature the female finch selects that male out of a hundred whose notes please her most. (28. 'Naturgeschichte der Stubenvögel,' 1840, s. 4. Mr. Harrison Weir likewise writes to me:--"I am informed that the best singing males generally get a mate first, when they are bred in the same room.") There can be no doubt that birds closely attend to each other's song. Mr. Weir has told me of the case of a bullfinch which had been taught to pipe a German waltz, and who was so good a performer that he cost ten guineas; when this bird was first introduced into a room where other birds were kept and he began to sing, all the others, consisting of about twenty linnets and canaries, ranged themselves on the nearest side of their cages, and listened with the greatest interest to the new performer. Many naturalists believe that the singing of birds is almost exclusively "the effect of rivalry and emulation," and not for the sake of charming their mates. This was the opinion of Daines Barrington and White of Selborne, who both especially attended to this subject. (29. 'Philosophical Transactions,' 1773, p. 263. White's 'Natural History of Selborne,' 1825, vol. i. p. 246.) Barrington, however, admits that "superiority in song gives to birds an amazing ascendancy over others, as is well known to bird-catchers." It is certain that there is an intense degree of rivalry between the males in their singing. Bird-fanciers match their birds to see which will sing longest; and I was told by Mr. Yarrell that a first-rate bird will sometimes sing till he drops down almost dead, or according to Bechstein (30. 'Naturgesch. der Stubenvögel,' 1840, s. 252.), quite dead from rupturing a vessel in the lungs. Whatever the cause may be, male birds, as I hear from Mr. Weir, often die suddenly during the season of song. That the habit of singing is sometimes quite independent of love is clear, for a sterile, hybrid canary-bird has been described (31. Mr. Bold, 'Zoologist,' 1843-44, p. 659.) as singing whilst viewing itself in a mirror, and then dashing at its own image; it likewise attacked with fury a female canary, when put into the same cage. The jealousy excited by the act of singing is constantly taken advantage of by bird-catchers; a male, in good song, is hidden and protected, whilst a stuffed bird, surrounded by limed twigs, is exposed to view. In this manner, as Mr. Weir informs me, a man has in the course of a single day caught fifty, and in one instance, seventy, male chaffinches. The power and inclination to sing differ so greatly with birds that although the price of an ordinary male chaffinch is only sixpence, Mr. Weir saw one bird for which the bird-catcher asked three pounds; the test of a really good singer being that it will continue to sing whilst the cage is swung round the owner's head. That male birds should sing from emulation as well as for charming the female, is not at all incompatible; and it might have been expected that these two habits would have concurred, like those of display and pugnacity. Some authors, however, argue that the song of the male cannot serve to charm the female, because the females of some few species, such as of the canary, robin, lark, and bullfinch, especially when in a state of widowhood, as Bechstein remarks, pour forth fairly melodious strains. In some of these cases the habit of singing may be in part attributed to the females having been highly fed and confined (32. D. Barrington, 'Philosophical Transactions,' 1773, p. 262. Bechstein, 'Stubenvögel,' 1840, s. 4.), for this disturbs all the functions connected with the reproduction of the species. Many instances have already been given of the partial transference of secondary masculine characters to the female, so that it is not at all surprising that the females of some species should possess the power of song. It has also been argued, that the song of the male cannot serve as a charm, because the males of certain species, for instance of the robin, sing during the autumn. (33. This is likewise the case with the water-ouzel; see Mr. Hepburn in the 'Zoologist,' 1845-46, p. 1068.) But nothing is more common than for animals to take pleasure in practising whatever instinct they follow at other times for some real good. How often do we see birds which fly easily, gliding and sailing through the air obviously for pleasure? The cat plays with the captured mouse, and the cormorant with the captured fish. The weaver-bird (Ploceus), when confined in a cage, amuses itself by neatly weaving blades of grass between the wires of its cage. Birds which habitually fight during the breeding-season are generally ready to fight at all times; and the males of the capercailzie sometimes hold their Balzen or leks at the usual place of assemblage during the autumn. (34. L. Lloyd, 'Game Birds of Sweden,' 1867, p. 25.) Hence it is not at all surprising that male birds should continue singing for their own amusement after the season for courtship is over. As shewn in a previous chapter, singing is to a certain extent an art, and is much improved by practice. Birds can be taught various tunes, and even the unmelodious sparrow has learnt to sing like a linnet. They acquire the song of their foster parents (35. Barrington, ibid. p. 264, Bechstein, ibid. s. 5.), and sometimes that of their neighbours. (36. Dureau de la Malle gives a curious instance ('Annales des Sc. Nat.' 3rd series, Zoolog., tom. x. p. 118) of some wild blackbirds in his garden in Paris, which naturally learnt a republican air from a caged bird.) All the common songsters belong to the Order of Insessores, and their vocal organs are much more complex than those of most other birds; yet it is a singular fact that some of the Insessores, such as ravens, crows, and magpies, possess the proper apparatus (37. Bishop, in 'Todd's Cyclopaedia of Anatomy and Physiology,' vol. iv. p. 1496.), though they never sing, and do not naturally modulate their voices to any great extent. Hunter asserts (38. As stated by Barrington in 'Philosophical Transactions,' 1773, p. 262.) that with the true songsters the muscles of the larynx are stronger in the males than in the females; but with this slight exception there is no difference in the vocal organs of the two sexes, although the males of most species sing so much better and more continuously than the females. It is remarkable that only small birds properly sing. The Australian genus Menura, however, must be excepted; for the Menura Alberti, which is about the size of a half-grown turkey, not only mocks other birds, but "its own whistle is exceedingly beautiful and varied." The males congregate and form "corroborying places," where they sing, raising and spreading their tails like peacocks, and drooping their wings. (39. Gould, 'Handbook to the Birds of Australia,' vol. i. 1865, pp. 308-310. See also Mr. T.W. Wood in the 'Student,' April 1870, p. 125.) It is also remarkable that birds which sing well are rarely decorated with brilliant colours or other ornaments. Of our British birds, excepting the bullfinch and goldfinch, the best songsters are plain-coloured. The kingfisher, bee-eater, roller, hoopoe, woodpeckers, etc., utter harsh cries; and the brilliant birds of the tropics are hardly ever songsters. (40. See remarks to this effect in Gould's 'Introduction to the Trochilidae,' 1861, p. 22.) Hence bright colours and the power of song seem to replace each other. We can perceive that if the plumage did not vary in brightness, or if bright colours were dangerous to the species, other means would be employed to charm the females; and melody of voice offers one such means. [Fig. 39. Tetrao cupido: male. (T.W. Wood.)] In some birds the vocal organs differ greatly in the two sexes. In the Tetrao cupido (Fig. 39) the male has two bare, orange-coloured sacks, one on each side of the neck; and these are largely inflated when the male, during the breeding-season, makes his curious hollow sound, audible at a great distance. Audubon proved that the sound was intimately connected with this apparatus (which reminds us of the air-sacks on each side of the mouth of certain male frogs), for he found that the sound was much diminished when one of the sacks of a tame bird was pricked, and when both were pricked it was altogether stopped. The female has "a somewhat similar, though smaller naked space of skin on the neck; but this is not capable of inflation." (41. 'The Sportsman and Naturalist in Canada,' by Major W. Ross King, 1866, pp. 144-146. Mr. T.W. Wood gives in the 'Student' (April 1870, p. 116) an excellent account of the attitude and habits of this bird during its courtship. He states that the ear-tufts or neck-plumes are erected, so that they meet over the crown of the head. See his drawing, Fig. 39.) The male of another kind of grouse (Tetrao urophasianus), whilst courting the female, has his "bare yellow oesophagus inflated to a prodigious size, fully half as large as the body"; and he then utters various grating, deep, hollow tones. With his neck-feathers erect, his wings lowered, and buzzing on the ground, and his long pointed tail spread out like a fan, he displays a variety of grotesque attitudes. The oesophagus of the female is not in any way remarkable. (42. Richardson, 'Fauna Bor. Americana: Birds,' 1831, p. 359. Audubon, ibid. vol. iv. p. 507.) [Fig. 40. The Umbrella-bird or Cephalopterus ornatus, male (from Brehm).] It seems now well made out that the great throat pouch of the European male bustard (Otis tarda), and of at least four other species, does not, as was formerly supposed, serve to hold water, but is connected with the utterance during the breeding-season of a peculiar sound resembling "oak." (43. The following papers have been lately written on this subject: Prof. A. Newton, in the 'Ibis,' 1862, p. 107; Dr. Cullen, ibid. 1865, p. 145; Mr. Flower, in 'Proc. Zool. Soc.' 1865, p. 747; and Dr. Murie, in 'Proc. Zool. Soc.' 1868, p. 471. In this latter paper an excellent figure is given of the male Australian Bustard in full display with the sack distended. It is a singular fact that the sack is not developed in all the males of the same species.) A crow-like bird inhabiting South America (see Cephalopterus ornatus, Fig. 40) is called the umbrella-bird, from its immense top knot, formed of bare white quills surmounted by dark-blue plumes, which it can elevate into a great dome no less than five inches in diameter, covering the whole head. This bird has on its neck a long, thin, cylindrical fleshy appendage, which is thickly clothed with scale-like blue feathers. It probably serves in part as an ornament, but likewise as a resounding apparatus; for Mr. Bates found that it is connected "with an unusual development of the trachea and vocal organs." It is dilated when the bird utters its singularly deep, loud and long sustained fluty note. The head-crest and neck-appendage are rudimentary in the female. (44. Bates, 'The Naturalist on the Amazons,' 1863, vol. ii. p. 284; Wallace, in 'Proceedings, Zoological Society,' 1850, p. 206. A new species, with a still larger neck-appendage (C. penduliger), has lately been discovered, see 'Ibis,' vol. i. p. 457.) The vocal organs of various web-footed and wading birds are extraordinarily complex, and differ to a certain extent in the two sexes. In some cases the trachea is convoluted, like a French horn, and is deeply embedded in the sternum. In the wild swan (Cygnus ferus) it is more deeply embedded in the adult male than in the adult female or young male. In the male Merganser the enlarged portion of the trachea is furnished with an additional pair of muscles. (45. Bishop, in Todd's 'Cyclopaedia of Anatomy and Physiology,' vol. iv. p. 1499.) In one of the ducks, however, namely Anas punctata, the bony enlargement is only a little more developed in the male than in the female. (46. Prof. Newton, 'Proc. Zoolog. Soc.' 1871, p. 651.) But the meaning of these differences in the trachea of the two sexes of the Anatidae is not understood; for the male is not always the more vociferous; thus with the common duck, the male hisses, whilst the female utters a loud quack. (47. The spoonbill (Platalea) has its trachea convoluted into a figure of eight, and yet this bird (Jerdon, 'Birds of India,' vol. iii. p. 763) is mute; but Mr. Blyth informs me that the convolutions are not constantly present, so that perhaps they are now tending towards abortion.) In both sexes of one of the cranes (Grus virgo) the trachea penetrates the sternum, but presents "certain sexual modifications." In the male of the black stork there is also a well-marked sexual difference in the length and curvature of the bronchi. (48. 'Elements of Comparative Anatomy,' by R. Wagner, Eng. translat. 1845, p. 111. With respect to the swan, as given above, Yarrell's 'History of British Birds,' 2nd edition, 1845, vol. iii. p. 193.) Highly important structures have, therefore, in these cases been modified according to sex. It is often difficult to conjecture whether the many strange cries and notes uttered by male birds during the breeding-season serve as a charm or merely as a call to the female. The soft cooing of the turtle-dove and of many pigeons, it may be presumed, pleases the female. When the female of the wild turkey utters her call in the morning, the male answers by a note which differs from the gobbling noise made, when with erected feathers, rustling wings and distended wattles, he puffs and struts before her. (49. C.L. Bonaparte, quoted in the 'Naturalist Library: Birds,' vol. xiv. p. 126.) The spel of the black-cock certainly serves as a call to the female, for it has been known to bring four or five females from a distance to a male under confinement; but as the black-cock continues his spel for hours during successive days, and in the case of the capercailzie "with an agony of passion," we are led to suppose that the females which are present are thus charmed. (50. L. Lloyd, 'The Game Birds of Sweden,' etc., 1867, pp. 22, 81.) The voice of the common rook is known to alter during the breeding-season, and is therefore in some way sexual. (51. Jenner, 'Philosophical Transactions,' 1824, p. 20.) But what shall we say about the harsh screams of, for instance, some kinds of macaws; have these birds as bad taste for musical sounds as they apparently have for colour, judging by the inharmonious contrast of their bright yellow and blue plumage? It is indeed possible that without any advantage being thus gained, the loud voices of many male birds may be the result of the inherited effects of the continued use of their vocal organs when excited by the strong passions of love, jealousy and rage; but to this point we shall recur when we treat of quadrupeds. We have as yet spoken only of the voice, but the males of various birds practise, during their courtship, what may be called instrumental music. Peacocks and Birds of Paradise rattle their quills together. Turkey-cocks scrape their wings against the ground, and some kinds of grouse thus produce a buzzing sound. Another North American grouse, the Tetrao umbellus, when with his tail erect, his ruffs displayed, "he shows off his finery to the females, who lie hid in the neighbourhood," drums by rapidly striking his wings together above his back, according to Mr. R. Haymond, and not, as Audubon thought, by striking them against his sides. The sound thus produced is compared by some to distant thunder, and by others to the quick roll of a drum. The female never drums, "but flies directly to the place where the male is thus engaged." The male of the Kalij-pheasant, in the Himalayas, often makes a singular drumming noise with his wings, not unlike the sound produced by shaking a stiff piece of cloth." On the west coast of Africa the little black-weavers (Ploceus?) congregate in a small party on the bushes round a small open space, and sing and glide through the air with quivering wings, "which make a rapid whirring sound like a child's rattle." One bird after another thus performs for hours together, but only during the courting-season. At this season, and at no other time, the males of certain night-jars (Caprimulgus) make a strange booming noise with their wings. The various species of woodpeckers strike a sonorous branch with their beaks, with so rapid a vibratory movement that "the head appears to be in two places at once." The sound thus produced is audible at a considerable distance but cannot be described; and I feel sure that its source would never be conjectured by any one hearing it for the first time. As this jarring sound is made chiefly during the breeding-season, it has been considered as a love-song; but it is perhaps more strictly a love-call. The female, when driven from her nest, has been observed thus to call her mate, who answered in the same manner and soon appeared. Lastly, the male hoopoe (Upupa epops) combines vocal and instrumental music; for during the breeding-season this bird, as Mr. Swinhoe observed, first draws in air, and then taps the end of its beak perpendicularly down against a stone or the trunk of a tree, "when the breath being forced down the tubular bill produces the correct sound." If the beak is not thus struck against some object, the sound is quite different. Air is at the same time swallowed, and the oesophagus thus becomes much swollen; and this probably acts as a resonator, not only with the hoopoe, but with pigeons and other birds. (52. For the foregoing facts see, on Birds of Paradise, Brehm, 'Thierleben,' Band iii. s. 325. On Grouse, Richardson, 'Fauna Bor. Americ.: Birds,' pp. 343 and 359; Major W. Ross King, 'The Sportsman in Canada,' 1866, p. 156; Mr. Haymond, in Prof. Cox's 'Geol. Survey of Indiana,' p. 227; Audubon, 'American Ornitholog. Biograph.' vol. i. p. 216. On the Kalij-pheasant, Jerdon, 'Birds of India,' vol. iii. p. 533. On the Weavers, Livingstone's 'Expedition to the Zambesi,' 1865, p. 425. On Woodpeckers, Macgillivray, 'Hist. of British Birds,' vol. iii. 1840, pp. 84, 88, 89, and 95. On the Hoopoe, Mr. Swinhoe, in 'Proc. Zoolog. Soc.' June 23, 1863 and 1871, p. 348. On the Night-jar, Audubon, ibid. vol. ii. p. 255, and 'American Naturalist,' 1873, p. 672. The English Night-jar likewise makes in the spring a curious noise during its rapid flight.) [Fig. 41. Outer tail-feather of Scolopax gallinago (from 'Proc. Zool. Soc.' 1858). Fig. 42. Outer tail-feather of Scolopax frenata. Fig. 43. Outer tail-feather of Scolopax javensis.] In the foregoing cases sounds are made by the aid of structures already present and otherwise necessary; but in the following cases certain feathers have been specially modified for the express purpose of producing sounds. The drumming, bleating, neighing, or thundering noise (as expressed by different observers) made by the common snipe (Scolopax gallinago) must have surprised every one who has ever heard it. This bird, during the pairing-season, flies to "perhaps a thousand feet in height," and after zig-zagging about for a time descends to the earth in a curved line, with outspread tail and quivering pinions, and surprising velocity. The sound is emitted only during this rapid descent. No one was able to explain the cause until M. Meves observed that on each side of the tail the outer feathers are peculiarly formed (Fig. 41), having a stiff sabre-shaped shaft with the oblique barbs of unusual length, the outer webs being strongly bound together. He found that by blowing on these feathers, or by fastening them to a long thin stick and waving them rapidly through the air, he could reproduce the drumming noise made by the living bird. Both sexes are furnished with these feathers, but they are generally larger in the male than in the female, and emit a deeper note. In some species, as in S. frenata (Fig. 42), four feathers, and in S. javensis (Fig. 43), no less than eight on each side of the tail are greatly modified. Different tones are emitted by the feathers of the different species when waved through the air; and the Scolopax Wilsonii of the United States makes a switching noise whilst descending rapidly to the earth. (53. See M. Meves' interesting paper in 'Proc. Zool. Soc.' 1858, p. 199. For the habits of the snipe, Macgillivray, 'History of British Birds,' vol. iv. p. 371. For the American snipe, Capt. Blakiston, 'Ibis,' vol. v. 1863, p. 131.) [Fig. 44. Primary wing-feather of a Humming-bird, the Selasphorus platycercus (from a sketch by Mr. Salvin). Upper figure, that of male; lower figure, corresponding feather of female.] In the male of the Chamaepetes unicolor (a large gallinaceous bird of America), the first primary wing-feather is arched towards the tip and is much more attenuated than in the female. In an allied bird, the Penelope nigra, Mr. Salvin observed a male, which, whilst it flew downwards "with outstretched wings, gave forth a kind of crashing rushing noise," like the falling of a tree. (54. Mr. Salvin, in 'Proceedings, Zoological Society,' 1867, p. 160. I am much indebted to this distinguished ornithologist for sketches of the feathers of the Chamaepetes, and for other information.) The male alone of one of the Indian bustards (Sypheotides auritus) has its primary wing-feathers greatly acuminated; and the male of an allied species is known to make a humming noise whilst courting the female. (55. Jerdon, 'Birds of India,' vol. iii. pp. 618, 621.) In a widely different group of birds, namely Humming-birds, the males alone of certain kinds have either the shafts of their primary wing-feathers broadly dilated, or the webs abruptly excised towards the extremity. The male, for instance, of Selasphorus platycercus, when adult, has the first primary wing-feather (Fig. 44), thus excised. Whilst flying from flower to flower he makes "a shrill, almost whistling noise" (56. Gould, 'Introduction to the Trochilidae,' 1861, p. 49. Salvin, 'Proceedings, Zoological Society,' 1867, p. 160.); but it did not appear to Mr. Salvin that the noise was intentionally made. [Fig. 45. Secondary wing-feathers of Pipra deliciosa (from Mr. Sclater, in 'Proc. Zool. Soc.' 1860). The three upper feathers, a, b, c, from the male; the three lower corresponding feathers, d, e, f, from the female. a and d, fifth secondary wing-feather of male and female, upper surface. b and e, sixth secondary, upper surface. c and f, seventh secondary, lower surface.] Lastly, in several species of a sub-genus of Pipra or Manakin, the males, as described by Mr. Sclater, have their SECONDARY wing-feathers modified in a still more remarkable manner. In the brilliantly-coloured P. deliciosa the first three secondaries are thick-stemmed and curved towards the body; in the fourth and fifth (Fig. 45, a) the change is greater; and in the sixth and seventh (b, c) the shaft "is thickened to an extraordinary degree, forming a solid horny lump." The barbs also are greatly changed in shape, in comparison with the corresponding feathers (d, e, f) in the female. Even the bones of the wing, which support these singular feathers in the male, are said by Mr. Fraser to be much thickened. These little birds make an extraordinary noise, the first "sharp note being not unlike the crack of a whip." (57. Sclater, in 'Proceedings, Zoological Society,' 1860, p. 90, and in 'Ibis,' vol. iv. 1862, p. 175. Also Salvin, in 'Ibis,' 1860, p. 37.) The diversity of the sounds, both vocal and instrumental, made by the males of many birds during the breeding-season, and the diversity of the means for producing such sounds, are highly remarkable. We thus gain a high idea of their importance for sexual purposes, and are reminded of the conclusion arrived at as to insects. It is not difficult to imagine the steps by which the notes of a bird, primarily used as a mere call or for some other purpose, might have been improved into a melodious love song. In the case of the modified feathers, by which the drumming, whistling, or roaring noises are produced, we know that some birds during their courtship flutter, shake, or rattle their unmodified feathers together; and if the females were led to select the best performers, the males which possessed the strongest or thickest, or most attenuated feathers, situated on any part of the body, would be the most successful; and thus by slow degrees the feathers might be modified to almost any extent. The females, of course, would not notice each slight successive alteration in shape, but only the sounds thus produced. It is a curious fact that in the same class of animals, sounds so different as the drumming of the snipe's tail, the tapping of the woodpecker's beak, the harsh trumpet-like cry of certain water-fowl, the cooing of the turtle-dove, and the song of the nightingale, should all be pleasing to the females of the several species. But we must not judge of the tastes of distinct species by a uniform standard; nor must we judge by the standard of man's taste. Even with man, we should remember what discordant noises, the beating of tom-toms and the shrill notes of reeds, please the ears of savages. Sir S. Baker remarks (58. 'The Nile Tributaries of Abyssinia,' 1867, p. 203.), that "as the stomach of the Arab prefers the raw meat and reeking liver taken hot from the animal, so does his ear prefer his equally coarse and discordant music to all other." LOVE ANTICS AND DANCES. The curious love gestures of some birds have already been incidentally noticed; so that little need here be added. In Northern America large numbers of a grouse, the Tetrao phasianellus, meet every morning during the breeding-season on a selected level spot, and here they run round and round in a circle of about fifteen or twenty feet in diameter, so that the ground is worn quite bare, like a fairy-ring. In these Partridge-dances, as they are called by the hunters, the birds assume the strangest attitudes, and run round, some to the left and some to the right. Audubon describes the males of a heron (Ardea herodias) as walking about on their long legs with great dignity before the females, bidding defiance to their rivals. With one of the disgusting carrion-vultures (Cathartes jota) the same naturalist states that "the gesticulations and parade of the males at the beginning of the love-season are extremely ludicrous." Certain birds perform their love-antics on the wing, as we have seen with the black African weaver, instead of on the ground. During the spring our little white-throat (Sylvia cinerea) often rises a few feet or yards in the air above some bush, and "flutters with a fitful and fantastic motion, singing all the while, and then drops to its perch." The great English bustard throws himself into indescribably odd attitudes whilst courting the female, as has been figured by Wolf. An allied Indian bustard (Otis bengalensis) at such times "rises perpendicularly into the air with a hurried flapping of his wings, raising his crest and puffing out the feathers of his neck and breast, and then drops to the ground;" he repeats this manoeuvre several times, at the same time humming in a peculiar tone. Such females as happen to be near "obey this saltatory summons," and when they approach he trails his wings and spreads his tail like a turkey-cock. (59. For Tetrao phasianellus, see Richardson, 'Fauna, Bor. America,' p. 361, and for further particulars Capt. Blakiston, 'Ibis,' 1863, p. 125. For the Cathartes and Ardea, Audubon, 'Ornithological Biography,' vol. ii. p. 51, and vol. iii. p. 89. On the White-throat, Macgillivray, 'History of British Birds,' vol. ii. p. 354. On the Indian Bustard, Jerdon, 'Birds of India,' vol. iii. p. 618.) [Fig. 46. Bower-bird, Chlamydera maculata, with bower (from Brehm).] But the most curious case is afforded by three allied genera of Australian birds, the famous Bower-birds,--no doubt the co-descendants of some ancient species which first acquired the strange instinct of constructing bowers for performing their love-antics. The bowers (Fig. 46), which, as we shall hereafter see, are decorated with feathers, shells, bones, and leaves, are built on the ground for the sole purpose of courtship, for their nests are formed in trees. Both sexes assist in the erection of the bowers, but the male is the principal workman. So strong is this instinct that it is practised under confinement, and Mr. Strange has described (60. Gould, 'Handbook to the Birds of Australia,' vol. i. pp. 444, 449, 455. The bower of the Satin Bower-bird may be seen in the Zoological Society's Gardens, Regent's Park.) the habits of some Satin Bower-birds which he kept in an aviary in New South Wales. "At times the male will chase the female all over the aviary, then go to the bower, pick up a gay feather or a large leaf, utter a curious kind of note, set all his feathers erect, run round the bower and become so excited that his eyes appear ready to start from his head; he continues opening first one wing then the other, uttering a low, whistling note, and, like the domestic cock, seems to be picking up something from the ground, until at last the female goes gently towards him." Captain Stokes has described the habits and "play-houses" of another species, the Great Bower-bird, which was seen "amusing itself by flying backwards and forwards, taking a shell alternately from each side, and carrying it through the archway in its mouth." These curious structures, formed solely as halls of assemblage, where both sexes amuse themselves and pay their court, must cost the birds much labour. The bower, for instance, of the Fawn-breasted species, is nearly four feet in length, eighteen inches in height, and is raised on a thick platform of sticks. DECORATION. I will first discuss the cases in which the males are ornamented either exclusively or in a much higher degree than the females, and in a succeeding chapter those in which both sexes are equally ornamented, and finally the rare cases in which the female is somewhat more brightly-coloured than the male. As with the artificial ornaments used by savage and civilised men, so with the natural ornaments of birds, the head is the chief seat of decoration. (61. See remarks to this effect, on the 'Feeling of Beauty among Animals,' by Mr. J. Shaw, in the 'Athenaeum,' Nov. 24th, 1866, p. 681.) The ornaments, as mentioned at the commencement of this chapter, are wonderfully diversified. The plumes on the front or back of the head consist of variously-shaped feathers, sometimes capable of erection or expansion, by which their beautiful colours are fully displayed. Elegant ear-tufts (Fig. 39) are occasionally present. The head is sometimes covered with velvety down, as with the pheasant; or is naked and vividly coloured. The throat, also, is sometimes ornamented with a beard, wattles, or caruncles. Such appendages are generally brightly-coloured, and no doubt serve as ornaments, though not always ornamental in our eyes; for whilst the male is in the act of courting the female, they often swell and assume vivid tints, as in the male turkey. At such times the fleshy appendages about the head of the male Tragopan pheasant (Ceriornis Temminckii) swell into a large lappet on the throat and into two horns, one on each side of the splendid top-knot; and these are then coloured of the most intense blue which I have ever beheld. (62. See Dr. Murie's account with coloured figures in 'Proceedings, Zoological Society,' 1872, p. 730.) The African hornbill (Bucorax abyssinicus) inflates the scarlet bladder-like wattle on its neck, and with its wings drooping and tail expanded "makes quite a grand appearance." (63. Mr. Monteiro, 'Ibis,' vol. iv. 1862, p. 339.) Even the iris of the eye is sometimes more brightly-coloured in the male than in the female; and this is frequently the case with the beak, for instance, in our common blackbird. In Buceros corrugatus, the whole beak and immense casque are coloured more conspicuously in the male than in the female; and "the oblique grooves upon the sides of the lower mandible are peculiar to the male sex." (64. 'Land and Water,' 1868, p. 217.) The head, again, often supports fleshy appendages, filaments, and solid protuberances. These, if not common to both sexes, are always confined to the males. The solid protuberances have been described in detail by Dr. W. Marshall (65. 'Ueber die Schädelhöcker,' etc., 'Niederland. Archiv. fur Zoologie,' B. I. Heft 2, 1872.), who shews that they are formed either of cancellated bone coated with skin, or of dermal and other tissues. With mammals true horns are always supported on the frontal bones, but with birds various bones have been modified for this purpose; and in species of the same group the protuberances may have cores of bone, or be quite destitute of them, with intermediate gradations connecting these two extremes. Hence, as Dr. Marshall justly remarks, variations of the most different kinds have served for the development through sexual selection of these ornamental appendages. Elongated feathers or plumes spring from almost every part of the body. The feathers on the throat and breast are sometimes developed into beautiful ruffs and collars. The tail-feathers are frequently increased in length; as we see in the tail-coverts of the peacock, and in the tail itself of the Argus pheasant. With the peacock even the bones of the tail have been modified to support the heavy tail-coverts. (66. Dr. W. Marshall, '�ber den Vogelschwanz,' ibid. B. I. Heft 2, 1872.) The body of the Argus is not larger than that of a fowl; yet the length from the end of the beak to the extremity of the tail is no less than five feet three inches (67. Jardine's 'Naturalist Library: Birds,' vol. xiv. p. 166.), and that of the beautifully ocellated secondary wing-feathers nearly three feet. In a small African night-jar (Cosmetornis vexillarius) one of the primary wing-feathers, during the breeding-season, attains a length of twenty-six inches, whilst the bird itself is only ten inches in length. In another closely-allied genus of night-jars, the shafts of the elongated wing-feathers are naked, except at the extremity, where there is a disc. (68. Sclater, in the 'Ibis,' vol. vi. 1864, p. 114; Livingstone, 'Expedition to the Zambesi,' 1865, p. 66.) Again, in another genus of night-jars, the tail-feathers are even still more prodigiously developed. In general the feathers of the tail are more often elongated than those of the wings, as any great elongation of the latter impedes flight. We thus see that in closely-allied birds ornaments of the same kind have been gained by the males through the development of widely different feathers. It is a curious fact that the feathers of species belonging to very distinct groups have been modified in almost exactly the same peculiar manner. Thus the wing-feathers in one of the above-mentioned night-jars are bare along the shaft, and terminate in a disc; or are, as they are sometimes called, spoon or racket-shaped. Feathers of this kind occur in the tail of a motmot (Eumomota superciliaris), of a king-fisher, finch, humming-bird, parrot, several Indian drongos (Dicrurus and Edolius, in one of which the disc stands vertically), and in the tail of certain birds of paradise. In these latter birds, similar feathers, beautifully ocellated, ornament the head, as is likewise the case with some gallinaceous birds. In an Indian bustard (Sypheotides auritus) the feathers forming the ear-tufts, which are about four inches in length, also terminate in discs. (69. Jerdon, 'Birds of India,' vol. iii. p. 620.) It is a most singular fact that the motmots, as Mr. Salvin has clearly shewn (70. 'Proceedings, Zoological Society,' 1873, p. 429.), give to their tail feathers the racket-shape by biting off the barbs, and, further, that this continued mutilation has produced a certain amount of inherited effect. [Fig. 47. Paradisea Papuana (T.W. Wood).] Again, the barbs of the feathers in various widely-distinct birds are filamentous or plumose, as with some herons, ibises, birds of paradise, and Gallinaceae. In other cases the barbs disappear, leaving the shafts bare from end to end; and these in the tail of the Paradisea apoda attain a length of thirty-four inches (71. Wallace, in 'Annals and Magazine of Natural History,' vol. xx. 1857, p. 416, and in his 'Malay Archipelago,' vol. ii. 1869, p. 390.): in P. Papuana (Fig. 47) they are much shorter and thin. Smaller feathers when thus denuded appear like bristles, as on the breast of the turkey-cock. As any fleeting fashion in dress comes to be admired by man, so with birds a change of almost any kind in the structure or colouring of the feathers in the male appears to have been admired by the female. The fact of the feathers in widely distinct groups having been modified in an analogous manner no doubt depends primarily on all the feathers having nearly the same structure and manner of development, and consequently tending to vary in the same manner. We often see a tendency to analogous variability in the plumage of our domestic breeds belonging to distinct species. Thus top-knots have appeared in several species. In an extinct variety of the turkey, the top-knot consisted of bare quills surmounted with plumes of down, so that they somewhat resembled the racket-shaped feathers above described. In certain breeds of the pigeon and fowl the feathers are plumose, with some tendency in the shafts to be naked. In the Sebastopol goose the scapular feathers are greatly elongated, curled, or even spirally twisted, with the margins plumose. (72. See my work on 'The Variation of Animals and Plants under Domestication,' vol. i. pp. 289, 293.) In regard to colour, hardly anything need here be said, for every one knows how splendid are the tints of many birds, and how harmoniously they are combined. The colours are often metallic and iridescent. Circular spots are sometimes surrounded by one or more differently shaded zones, and are thus converted into ocelli. Nor need much be said on the wonderful difference between the sexes of many birds. The common peacock offers a striking instance. Female birds of paradise are obscurely coloured and destitute of all ornaments, whilst the males are probably the most highly decorated of all birds, and in so many different ways that they must be seen to be appreciated. The elongated and golden-orange plumes which spring from beneath the wings of the Paradisea apoda, when vertically erected and made to vibrate, are described as forming a sort of halo, in the centre of which the head "looks like a little emerald sun with its rays formed by the two plumes." (73. Quoted from M. de Lafresnaye in 'Annals and Mag. of Natural History,' vol. xiii. 1854, p. 157: see also Mr. Wallace's much fuller account in vol. xx. 1857, p. 412, and in his 'Malay Archipelago.') In another most beautiful species the head is bald, "and of a rich cobalt blue, crossed by several lines of black velvety feathers." (74. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 405.) [Fig. 48. Lophornis ornatus, male and female (from Brehm). Fig. 49. Spathura underwoodi, male and female (from Brehm).] Male humming-birds (Figs. 48 and 49) almost vie with birds of paradise in their beauty, as every one will admit who has seen Mr. Gould's splendid volumes, or his rich collection. It is very remarkable in how many different ways these birds are ornamented. Almost every part of their plumage has been taken advantage of, and modified; and the modifications have been carried, as Mr. Gould shewed me, to a wonderful extreme in some species belonging to nearly every sub-group. Such cases are curiously like those which we see in our fancy breeds, reared by man for the sake of ornament; certain individuals originally varied in one character, and other individuals of the same species in other characters; and these have been seized on by man and much augmented--as shewn by the tail of the fantail-pigeon, the hood of the jacobin, the beak and wattle of the carrier, and so forth. The sole difference between these cases is that in the one, the result is due to man's selection, whilst in the other, as with humming-birds, birds of paradise, etc., it is due to the selection by the females of the more beautiful males. I will mention only one other bird, remarkable from the extreme contrast in colour between the sexes, namely the famous bell-bird (Chasmorhynchus niveus) of S. America, the note of which can be distinguished at the distance of nearly three miles, and astonishes every one when first hearing it. The male is pure white, whilst the female is dusky-green; and white is a very rare colour in terrestrial species of moderate size and inoffensive habits. The male, also, as described by Waterton, has a spiral tube, nearly three inches in length, which rises from the base of the beak. It is jet-black, dotted over with minute downy feathers. This tube can be inflated with air, through a communication with the palate; and when not inflated hangs down on one side. The genus consists of four species, the males of which are very distinct, whilst the females, as described by Mr. Sclater in a very interesting paper, closely resemble each other, thus offering an excellent instance of the common rule that within the same group the males differ much more from each other than do the females. In a second species (C. nudicollis) the male is likewise snow-white, with the exception of a large space of naked skin on the throat and round the eyes, which during the breeding-season is of a fine green colour. In a third species (C. tricarunculatus) the head and neck alone of the male are white, the rest of the body being chestnut-brown, and the male of this species is provided with three filamentous projections half as long as the body--one rising from the base of the beak, and the two others from the corners of the mouth. (75. Mr. Sclater, 'Intellectual Observer,' Jan. 1867. Waterton's 'Wanderings,' p. 118. See also Mr. Salvin's interesting paper, with a plate, in the 'Ibis,' 1865, p. 90.) The coloured plumage and certain other ornaments of the adult males are either retained for life, or are periodically renewed during the summer and breeding-season. At this same season the beak and naked skin about the head frequently change colour, as with some herons, ibises, gulls, one of the bell-birds just noticed, etc. In the white ibis, the cheeks, the inflatable skin of the throat, and the basal portion of the beak then become crimson. (76. 'Land and Water,' 1867, p. 394.) In one of the rails, Gallicrex cristatus, a large red caruncle is developed during this period on the head of the male. So it is with a thin horny crest on the beak of one of the pelicans, P. erythrorhynchus; for, after the breeding-season, these horny crests are shed, like horns from the heads of stags, and the shore of an island in a lake in Nevada was found covered with these curious exuviae. (77. Mr. D.G. Elliot, in 'Proc. Zool. Soc.' 1869, p. 589.) Changes of colour in the plumage according to the season depend, firstly on a double annual moult, secondly on an actual change of colour in the feathers themselves, and thirdly on their dull-coloured margins being periodically shed, or on these three processes more or less combined. The shedding of the deciduary margins may be compared with the shedding of their down by very young birds; for the down in most cases arises from the summits of the first true feathers. (78. Nitzsch's 'Pterylography,' edited by P.L. Sclater, Ray Society, 1867, p. 14.) With respect to the birds which annually undergo a double moult, there are, firstly, some kinds, for instance snipes, swallow-plovers (Glareolae), and curlews, in which the two sexes resemble each other, and do not change colour at any season. I do not know whether the winter plumage is thicker and warmer than the summer plumage, but warmth seems the most probable end attained of a double moult, where there is no change of colour. Secondly, there are birds, for instance, certain species of Totanus and other Grallatores, the sexes of which resemble each other, but in which the summer and winter plumage differ slightly in colour. The difference, however, in these cases is so small that it can hardly be an advantage to them; and it may, perhaps, be attributed to the direct action of the different conditions to which the birds are exposed during the two seasons. Thirdly, there are many other birds the sexes of which are alike, but which are widely different in their summer and winter plumage. Fourthly, there are birds the sexes of which differ from each other in colour; but the females, though moulting twice, retain the same colours throughout the year, whilst the males undergo a change of colour, sometimes a great one, as with certain bustards. Fifthly and lastly, there are birds the sexes of which differ from each other in both their summer and winter plumage; but the male undergoes a greater amount of change at each recurrent season than the female--of which the ruff (Machetes pugnax) offers a good instance. With respect to the cause or purpose of the differences in colour between the summer and winter plumage, this may in some instances, as with the ptarmigan (79. The brown mottled summer plumage of the ptarmigan is of as much importance to it, as a protection, as the white winter plumage; for in Scandinavia during the spring, when the snow has disappeared, this bird is known to suffer greatly from birds of prey, before it has acquired its summer dress: see Wilhelm von Wright, in Lloyd, 'Game Birds of Sweden,' 1867, p. 125.), serve during both seasons as a protection. When the difference between the two plumages is slight it may perhaps be attributed, as already remarked, to the direct action of the conditions of life. But with many birds there can hardly be a doubt that the summer plumage is ornamental, even when both sexes are alike. We may conclude that this is the case with many herons, egrets, etc., for they acquire their beautiful plumes only during the breeding-season. Moreover, such plumes, top-knots, etc., though possessed by both sexes, are occasionally a little more developed in the male than in the female; and they resemble the plumes and ornaments possessed by the males alone of other birds. It is also known that confinement, by affecting the reproductive system of male birds, frequently checks the development of their secondary sexual characters, but has no immediate influence on any other characters; and I am informed by Mr. Bartlett that eight or nine specimens of the Knot (Tringa canutus) retained their unadorned winter plumage in the Zoological Gardens throughout the year, from which fact we may infer that the summer plumage, though common to both sexes, partakes of the nature of the exclusively masculine plumage of many other birds. (80. In regard to the previous statements on moulting, see, on snipes, etc., Macgillivray, 'Hist. Brit. Birds,' vol. iv. p. 371; on Glareolae, curlews, and bustards, Jerdon, 'Birds of India,' vol. iii. pp. 615, 630, 683; on Totanus, ibid. p. 700; on the plumes of herons, ibid. p. 738, and Macgillivray, vol. iv. pp. 435 and 444, and Mr. Stafford Allen, in the 'Ibis,' vol. v. 1863, p. 33.) From the foregoing facts, more especially from neither sex of certain birds changing colour during either annual moult, or changing so slightly that the change can hardly be of any service to them, and from the females of other species moulting twice yet retaining the same colours throughout the year, we may conclude that the habit of annually moulting twice has not been acquired in order that the male should assume an ornamental character during the breeding-season; but that the double moult, having been originally acquired for some distinct purpose, has subsequently been taken advantage of in certain cases for gaining a nuptial plumage. It appears at first sight a surprising circumstance that some closely-allied species should regularly undergo a double annual moult, and others only a single one. The ptarmigan, for instance, moults twice or even thrice in the year, and the blackcock only once: some of the splendidly coloured honey-suckers (Nectariniae) of India and some sub-genera of obscurely coloured pipits (Anthus) have a double, whilst others have only a single annual moult. (81. On the moulting of the ptarmigan, see Gould's 'Birds of Great Britain.' On the honey-suckers, Jerdon, 'Birds of India,' vol. i. pp. 359, 365, 369. On the moulting of Anthus, see Blyth, in 'Ibis,' 1867, p. 32.) But the gradations in the manner of moulting, which are known to occur with various birds, shew us how species, or whole groups, might have originally acquired their double annual moult, or having once gained the habit, have again lost it. With certain bustards and plovers the vernal moult is far from complete, some feathers being renewed, and some changed in colour. There is also reason to believe that with certain bustards and rail-like birds, which properly undergo a double moult, some of the older males retain their nuptial plumage throughout the year. A few highly modified feathers may merely be added during the spring to the plumage, as occurs with the disc-formed tail-feathers of certain drongos (Bhringa) in India, and with the elongated feathers on the back, neck, and crest of certain herons. By such steps as these, the vernal moult might be rendered more and more complete, until a perfect double moult was acquired. Some of the birds of paradise retain their nuptial feathers throughout the year, and thus have only a single moult; others cast them directly after the breeding-season, and thus have a double moult; and others again cast them at this season during the first year, but not afterwards; so that these latter species are intermediate in their manner of moulting. There is also a great difference with many birds in the length of time during which the two annual plumages are retained; so that the one might come to be retained for the whole year, and the other completely lost. Thus in the spring Machetes pugnax retains his ruff for barely two months. In Natal the male widow-bird (Chera progne) acquires his fine plumage and long tail-feathers in December or January, and loses them in March; so that they are retained only for about three months. Most species, which undergo a double moult, keep their ornamental feathers for about six months. The male, however, of the wild Gallus bankiva retains his neck-hackles for nine or ten months; and when these are cast off, the underlying black feathers on the neck are fully exposed to view. But with the domesticated descendant of this species, the neck-hackles of the male are immediately replaced by new ones; so that we here see, as to part of the plumage, a double moult changed under domestication into a single moult. (82. For the foregoing statements in regard to partial moults, and on old males retaining their nuptial plumage, see Jerdon, on bustards and plovers, in 'Birds of India,' vol. iii. pp. 617, 637, 709, 711. Also Blyth in 'Land and Water,' 1867, p. 84. On the moulting of Paradisea, see an interesting article by Dr. W. Marshall, 'Archives Neerlandaises,' tom. vi. 1871. On the Vidua, 'Ibis,' vol. iii. 1861, p. 133. On the Drongo-shrikes, Jerdon, ibid. vol. i. p. 435. On the vernal moult of the Herodias bubulcus, Mr. S.S. Allen, in 'Ibis,' 1863, p. 33. On Gallus bankiva, Blyth, in 'Annals and Mag. of Natural History,' vol. i. 1848, p. 455; see, also, on this subject, my 'Variation of Animals under Domestication,' vol. i. p. 236.) The common drake (Anas boschas), after the breeding-season, is well known to lose his male plumage for a period of three months, during which time he assumes that of the female. The male pin-tail duck (Anas acuta) loses his plumage for the shorter period of six weeks or two months; and Montagu remarks that "this double moult within so short a time is a most extraordinary circumstance, that seems to bid defiance to all human reasoning." But the believer in the gradual modification of species will be far from feeling surprise at finding gradations of all kinds. If the male pin-tail were to acquire his new plumage within a still shorter period, the new male feathers would almost necessarily be mingled with the old, and both with some proper to the female; and this apparently is the case with the male of a not distantly-allied bird, namely the Merganser serrator, for the males are said to "undergo a change of plumage, which assimilates them in some measure to the female." By a little further acceleration in the process, the double moult would be completely lost. (83. See Macgillivray, 'Hist. British Birds' (vol. v. pp. 34, 70, and 223), on the moulting of the Anatidae, with quotations from Waterton and Montagu. Also Yarrell, 'History of British Birds,' vol. iii. p. 243.) Some male birds, as before stated, become more brightly coloured in the spring, not by a vernal moult, but either by an actual change of colour in the feathers, or by their obscurely-coloured deciduary margins being shed. Changes of colour thus caused may last for a longer or shorter time. In the Pelecanus onocrotalus a beautiful rosy tint, with lemon-coloured marks on the breast, overspreads the whole plumage in the spring; but these tints, as Mr. Sclater states, "do not last long, disappearing generally in about six weeks or two months after they have been attained." Certain finches shed the margins of their feathers in the spring, and then become brighter coloured, while other finches undergo no such change. Thus the Fringilla tristis of the United States (as well as many other American species) exhibits its bright colours only when the winter is past, whilst our goldfinch, which exactly represents this bird in habits, and our siskin, which represents it still more closely in structure, undergo no such annual change. But a difference of this kind in the plumage of allied species is not surprising, for with the common linnet, which belongs to the same family, the crimson forehead and breast are displayed only during the summer in England, whilst in Madeira these colours are retained throughout the year. (84. On the pelican, see Sclater, in 'Proc. Zool. Soc.' 1868, p. 265. On the American finches, see Audubon, 'Ornithological Biography,' vol. i. pp. 174, 221, and Jerdon, 'Birds of India,' vol. ii. p. 383. On the Fringilla cannabina of Madeira, Mr. E. Vernon Harcourt, 'Ibis,' vol. v. 1863, p. 230.) DISPLAY BY MALE BIRDS OF THEIR PLUMAGE. Ornaments of all kinds, whether permanently or temporarily gained, are sedulously displayed by the males, and apparently serve to excite, attract, or fascinate the females. But the males will sometimes display their ornaments, when not in the presence of the females, as occasionally occurs with grouse at their balz-places, and as may be noticed with the peacock; this latter bird, however, evidently wishes for a spectator of some kind, and, as I have often seen, will shew off his finery before poultry, or even pigs. (85. See also 'Ornamental Poultry,' by Rev. E.S. Dixon, 1848, p. 8.) All naturalists who have closely attended to the habits of birds, whether in a state of nature or under confinement, are unanimously of opinion that the males take delight in displaying their beauty. Audubon frequently speaks of the male as endeavouring in various ways to charm the female. Mr. Gould, after describing some peculiarities in a male humming-bird, says he has no doubt that it has the power of displaying them to the greatest advantage before the female. Dr. Jerdon (86. 'Birds of India,' introduct., vol. i. p. xxiv.; on the peacock, vol. iii. p. 507. See Gould's 'Introduction to Trochilidae,' 1861, pp. 15 and 111.) insists that the beautiful plumage of the male serves "to fascinate and attract the female." Mr. Bartlett, at the Zoological Gardens, expressed himself to me in the strongest terms to the same effect. [Fig. 50. Rupicola crocea, male (T.W. Wood).] It must be a grand sight in the forests of India "to come suddenly on twenty or thirty pea-fowl, the males displaying their gorgeous trains, and strutting about in all the pomp of pride before the gratified females." The wild turkey-cock erects his glittering plumage, expands his finely-zoned tail and barred wing-feathers, and altogether, with his crimson and blue wattles, makes a superb, though, to our eyes, grotesque appearance. Similar facts have already been given with respect to grouse of various kinds. Turning to another Order: The male Rupicola crocea (Fig. 50) is one of the most beautiful birds in the world, being of a splendid orange, with some of the feathers curiously truncated and plumose. The female is brownish-green, shaded with red, and has a much smaller crest. Sir R. Schomburgk has described their courtship; he found one of their meeting-places where ten males and two females were present. The space was from four to five feet in diameter, and appeared to have been cleared of every blade of grass and smoothed as if by human hands. A male "was capering, to the apparent delight of several others. Now spreading its wings, throwing up its head, or opening its tail like a fan; now strutting about with a hopping gait until tired, when it gabbled some kind of note, and was relieved by another. Thus three of them successively took the field, and then, with self-approbation, withdrew to rest." The Indians, in order to obtain their skins, wait at one of the meeting-places till the birds are eagerly engaged in dancing, and then are able to kill with their poisoned arrows four or five males, one after the other. (87. 'Journal of R. Geograph. Soc.' vol. x. 1840, p. 236.) With birds of paradise a dozen or more full-plumaged males congregate in a tree to hold a dancing-party, as it is called by the natives: and here they fly about, raise their wings, elevate their exquisite plumes, and make them vibrate, and the whole tree seems, as Mr. Wallace remarks, to be filled with waving plumes. When thus engaged, they become so absorbed that a skilful archer may shoot nearly the whole party. These birds, when kept in confinement in the Malay Archipelago, are said to take much care in keeping their feathers clean; often spreading them out, examining them, and removing every speck of dirt. One observer, who kept several pairs alive, did not doubt that the display of the male was intended to please the female. (88. 'Annals and Mag. of Nat. Hist.' vol. xiii. 1854, p. 157; also Wallace, ibid. vol. xx. 1857, p. 412, and 'The Malay Archipelago,' vol. ii. 1869, p. 252. Also Dr. Bennett, as quoted by Brehm, 'Thierleben,' B. iii. s. 326.) [Fig. 51. Polyplectron chinquis, male (T.W. Wood).] The Gold and Amherst pheasants during their courtship not only expand and raise their splendid frills, but twist them, as I have myself seen, obliquely towards the female on whichever side she may be standing, obviously in order that a large surface may be displayed before her. (89. Mr. T.W. Wood has given ('The Student,' April 1870, p. 115) a full account of this manner of display, by the Gold pheasant and by the Japanese pheasant, Ph. versicolor; and he calls it the lateral or one-sided display.) They likewise turn their beautiful tails and tail-coverts a little towards the same side. Mr. Bartlett has observed a male Polyplectron (Fig. 51) in the act of courtship, and has shewn me a specimen stuffed in the attitude then assumed. The tail and wing-feathers of this bird are ornamented with beautiful ocelli, like those on the peacock's train. Now when the peacock displays himself, he expands and erects his tail transversely to his body, for he stands in front of the female, and has to shew off, at the same time, his rich blue throat and breast. But the breast of the Polyplectron is obscurely coloured, and the ocelli are not confined to the tail-feathers. Consequently the Polyplectron does not stand in front of the female; but he erects and expands his tail-feathers a little obliquely, lowering the expanded wing on the same side, and raising that on the opposite side. In this attitude the ocelli over the whole body are exposed at the same time before the eyes of the admiring female in one grand bespangled expanse. To whichever side she may turn, the expanded wings and the obliquely-held tail are turned towards her. The male Tragopan pheasant acts in nearly the same manner, for he raises the feathers of the body, though not the wing itself, on the side which is opposite to the female, and which would otherwise be concealed, so that nearly all the beautifully spotted feathers are exhibited at the same time. [Fig. 52. Side view of male Argus pheasant, whilst displaying before the female. Observed and sketched from nature by T.W. Wood.] The Argus pheasant affords a much more remarkable case. The immensely developed secondary wing-feathers are confined to the male; and each is ornamented with a row of from twenty to twenty-three ocelli, above an inch in diameter. These feathers are also elegantly marked with oblique stripes and rows of spots of a dark colour, like those on the skin of a tiger and leopard combined. These beautiful ornaments are hidden until the male shows himself off before the female. He then erects his tail, and expands his wing-feathers into a great, almost upright, circular fan or shield, which is carried in front of the body. The neck and head are held on one side, so that they are concealed by the fan; but the bird in order to see the female, before whom he is displaying himself, sometimes pushes his head between two of the long wing-feathers (as Mr. Bartlett has seen), and then presents a grotesque appearance. This must be a frequent habit with the bird in a state of nature, for Mr. Bartlett and his son on examining some perfect skins sent from the East, found a place between two of the feathers which was much frayed, as if the head had here frequently been pushed through. Mr. Wood thinks that the male can also peep at the female on one side, beyond the margin of the fan. The ocelli on the wing-feathers are wonderful objects; for they are so shaded that, as the Duke of Argyll remarks (90. 'The Reign of Law,' 1867, p. 203.), they stand out like balls lying loosely within sockets. When I looked at the specimen in the British Museum, which is mounted with the wings expanded and trailing downwards, I was however greatly disappointed, for the ocelli appeared flat, or even concave. But Mr. Gould soon made the case clear to me, for he held the feathers erect, in the position in which they would naturally be displayed, and now, from the light shining on them from above, each ocellus at once resembled the ornament called a ball and socket. These feathers have been shown to several artists, and all have expressed their admiration at the perfect shading. It may well be asked, could such artistically shaded ornaments have been formed by means of sexual selection? But it will be convenient to defer giving an answer to this question until we treat in the next chapter of the principle of gradation. The foregoing remarks relate to the secondary wing-feathers, but the primary wing-feathers, which in most gallinaceous birds are uniformly coloured, are in the Argus pheasant equally wonderful. They are of a soft brown tint with numerous dark spots, each of which consists of two or three black dots with a surrounding dark zone. But the chief ornament is a space parallel to the dark-blue shaft, which in outline forms a perfect second feather lying within the true feather. This inner part is coloured of a lighter chestnut, and is thickly dotted with minute white points. I have shewn this feather to several persons, and many have admired it even more than the ball and socket feathers, and have declared that it was more like a work of art than of nature. Now these feathers are quite hidden on all ordinary occasions, but are fully displayed, together with the long secondary feathers, when they are all expanded together so as to form the great fan or shield. The case of the male Argus pheasant is eminently interesting, because it affords good evidence that the most refined beauty may serve as a sexual charm, and for no other purpose. We must conclude that this is the case, as the secondary and primary wing-feathers are not at all displayed, and the ball and socket ornaments are not exhibited in full perfection until the male assumes the attitude of courtship. The Argus pheasant does not possess brilliant colours, so that his success in love appears to depend on the great size of his plumes, and on the elaboration of the most elegant patterns. Many will declare that it is utterly incredible that a female bird should be able to appreciate fine shading and exquisite patterns. It is undoubtedly a marvellous fact that she should possess this almost human degree of taste. He who thinks that he can safely gauge the discrimination and taste of the lower animals may deny that the female Argus pheasant can appreciate such refined beauty; but he will then be compelled to admit that the extraordinary attitudes assumed by the male during the act of courtship, by which the wonderful beauty of his plumage is fully displayed, are purposeless; and this is a conclusion which I for one will never admit. Although so many pheasants and allied gallinaceous birds carefully display their plumage before the females, it is remarkable, as Mr. Bartlett informs me, that this is not the case with the dull-coloured Eared and Cheer pheasants (Crossoptilon auritum and Phasianus wallichii); so that these birds seem conscious that they have little beauty to display. Mr. Bartlett has never seen the males of either of these species fighting together, though he has not had such good opportunities for observing the Cheer as the Eared pheasant. Mr. Jenner Weir, also, finds that all male birds with rich or strongly-characterised plumage are more quarrelsome than the dull-coloured species belonging to the same groups. The goldfinch, for instance, is far more pugnacious than the linnet, and the blackbird than the thrush. Those birds which undergo a seasonal change of plumage likewise become much more pugnacious at the period when they are most gaily ornamented. No doubt the males of some obscurely-coloured birds fight desperately together, but it appears that when sexual selection has been highly influential, and has given bright colours to the males of any species, it has also very often given a strong tendency to pugnacity. We shall meet with nearly analogous cases when we treat of mammals. On the other hand, with birds the power of song and brilliant colours have rarely been both acquired by the males of the same species; but in this case the advantage gained would have been the same, namely success in charming the female. Nevertheless it must be owned that the males of several brilliantly coloured birds have had their feathers specially modified for the sake of producing instrumental music, though the beauty of this cannot be compared, at least according to our taste, with that of the vocal music of many songsters. We will now turn to male birds which are not ornamented in any high degree, but which nevertheless display during their courtship whatever attractions they may possess. These cases are in some respects more curious than the foregoing, and have been but little noticed. I owe the following facts to Mr. Weir, who has long kept confined birds of many kinds, including all the British Fringillidae and Emberizidae. The facts have been selected from a large body of valuable notes kindly sent me by him. The bullfinch makes his advances in front of the female, and then puffs out his breast, so that many more of the crimson feathers are seen at once than otherwise would be the case. At the same time he twists and bows his black tail from side to side in a ludicrous manner. The male chaffinch also stands in front of the female, thus shewing his red breast and "blue bell," as the fanciers call his head; the wings at the same time being slightly expanded, with the pure white bands on the shoulders thus rendered conspicuous. The common linnet distends his rosy breast, slightly expands his brown wings and tail, so as to make the best of them by exhibiting their white edgings. We must, however, be cautious in concluding that the wings are spread out solely for display, as some birds do so whose wings are not beautiful. This is the case with the domestic cock, but it is always the wing on the side opposite to the female which is expanded, and at the same time scraped on the ground. The male goldfinch behaves differently from all other finches: his wings are beautiful, the shoulders being black, with the dark-tipped wing-feathers spotted with white and edged with golden yellow. When he courts the female, he sways his body from side to side, and quickly turns his slightly expanded wings first to one side, then to the other, with a golden flashing effect. Mr. Weir informs me that no other British finch turns thus from side to side during his courtship, not even the closely-allied male siskin, for he would not thus add to his beauty. Most of the British Buntings are plain coloured birds; but in the spring the feathers on the head of the male reed-bunting (Emberiza schoeniculus) acquire a fine black colour by the abrasion of the dusky tips; and these are erected during the act of courtship. Mr. Weir has kept two species of Amadina from Australia: the A. castanotis is a very small and chastely coloured finch, with a dark tail, white rump, and jet-black upper tail-coverts, each of the latter being marked with three large conspicuous oval spots of white. (91. For the description of these birds, see Gould's 'Handbook to the Birds of Australia,' vol. i. 1865, p. 417.) This species, when courting the female, slightly spreads out and vibrates these parti-coloured tail-coverts in a very peculiar manner. The male Amadina Lathami behaves very differently, exhibiting before the female his brilliantly spotted breast, scarlet rump, and scarlet upper tail-coverts. I may here add from Dr. Jerdon that the Indian bulbul (Pycnonotus hoemorrhous) has its under tail-coverts of a crimson colour, and these, it might be thought, could never be well exhibited; but the bird "when excited often spreads them out laterally, so that they can be seen even from above." (92. 'Birds of India,' vol. ii. p. 96.) The crimson under tail-coverts of some other birds, as with one of the woodpeckers, Picus major, can be seen without any such display. The common pigeon has iridescent feathers on the breast, and every one must have seen how the male inflates his breast whilst courting the female, thus shewing them off to the best advantage. One of the beautiful bronze-winged pigeons of Australia (Ocyphaps lophotes) behaves, as described to me by Mr. Weir, very differently: the male, whilst standing before the female, lowers his head almost to the ground, spreads out and raises his tail, and half expands his wings. He then alternately and slowly raises and depresses his body, so that the iridescent metallic feathers are all seen at once, and glitter in the sun. Sufficient facts have now been given to shew with what care male birds display their various charms, and this they do with the utmost skill. Whilst preening their feathers, they have frequent opportunities for admiring themselves, and of studying how best to exhibit their beauty. But as all the males of the same species display themselves in exactly the same manner, it appears that actions, at first perhaps intentional, have become instinctive. If so, we ought not to accuse birds of conscious vanity; yet when we see a peacock strutting about, with expanded and quivering tail-feathers, he seems the very emblem of pride and vanity. The various ornaments possessed by the males are certainly of the highest importance to them, for in some cases they have been acquired at the expense of greatly impeded powers of flight or of running. The African night-jar (Cosmetornis), which during the pairing-season has one of its primary wing-feathers developed into a streamer of very great length, is thereby much retarded in its flight, although at other times remarkable for its swiftness. The "unwieldy size" of the secondary wing-feathers of the male Argus pheasant is said "almost entirely to deprive the bird of flight." The fine plumes of male birds of paradise trouble them during a high wind. The extremely long tail-feathers of the male widow-birds (Vidua) of Southern Africa render "their flight heavy;" but as soon as these are cast off they fly as well as the females. As birds always breed when food is abundant, the males probably do not suffer much inconvenience in searching for food from their impeded powers of movement; but there can hardly be a doubt that they must be much more liable to be struck down by birds of prey. Nor can we doubt that the long train of the peacock and the long tail and wing-feathers of the Argus pheasant must render them an easier prey to any prowling tiger-cat than would otherwise be the case. Even the bright colours of many male birds cannot fail to make them conspicuous to their enemies of all kinds. Hence, as Mr. Gould has remarked, it probably is that such birds are generally of a shy disposition, as if conscious that their beauty was a source of danger, and are much more difficult to discover or approach, than the sombre coloured and comparatively tame females or than the young and as yet unadorned males. (93. On the Cosmetornis, see Livingstone's 'Expedition to the Zambesi,' 1865, p. 66. On the Argus pheasant, Jardine's 'Nat. Hist. Lib.: Birds,' vol. xiv. p. 167. On Birds of Paradise, Lesson, quoted by Brehm, 'Thierleben,' B. iii. s. 325. On the widow-bird, Barrow's 'Travels in Africa,' vol. i. p. 243, and 'Ibis,' vol. iii. 1861 p. 133. Mr. Gould, on the shyness of male birds, 'Handbook to Birds of Australia,' vol. i. 1865, pp. 210, 457.) It is a more curious fact that the males of some birds which are provided with special weapons for battle, and which in a state of nature are so pugnacious that they often kill each other, suffer from possessing certain ornaments. Cock-fighters trim the hackles and cut off the combs and gills of their cocks; and the birds are then said to be dubbed. An undubbed bird, as Mr. Tegetmeier insists, "is at a fearful disadvantage; the comb and gills offer an easy hold to his adversary's beak, and as a cock always strikes where he holds, when once he has seized his foe, he has him entirely in his power. Even supposing that the bird is not killed, the loss of blood suffered by an undubbed cock is much greater than that sustained by one that has been trimmed." (94. Tegetmeier, 'The Poultry Book,' 1866, p. 139.) Young turkey-cocks in fighting always seize hold of each other's wattles; and I presume that the old birds fight in the same manner. It may perhaps be objected that the comb and wattles are not ornamental, and cannot be of service to the birds in this way; but even to our eyes, the beauty of the glossy black Spanish cock is much enhanced by his white face and crimson comb; and no one who has ever seen the splendid blue wattles of the male Tragopan pheasant distended in courtship can for a moment doubt that beauty is the object gained. From the foregoing facts we clearly see that the plumes and other ornaments of the males must be of the highest importance to them; and we further see that beauty is even sometimes more important than success in battle. CHAPTER XIV. BIRDS--continued. Choice exerted by the female--Length of courtship--Unpaired birds--Mental qualities and taste for the beautiful--Preference or antipathy shewn by the female for particular males--Variability of birds--Variations sometimes abrupt--Laws of variation--Formation of ocelli--Gradations of character--Case of Peacock, Argus pheasant, and Urosticte. When the sexes differ in beauty or in the power of singing, or in producing what I have called instrumental music, it is almost invariably the male who surpasses the female. These qualities, as we have just seen, are evidently of high importance to the male. When they are gained for only a part of the year it is always before the breeding-season. It is the male alone who elaborately displays his varied attractions, and often performs strange antics on the ground or in the air, in the presence of the female. Each male drives away, or if he can, kills his rivals. Hence we may conclude that it is the object of the male to induce the female to pair with him, and for this purpose he tries to excite or charm her in various ways; and this is the opinion of all those who have carefully studied the habits of living birds. But there remains a question which has an all important bearing on sexual selection, namely, does every male of the same species excite and attract the female equally? Or does she exert a choice, and prefer certain males? This latter question can be answered in the affirmative by much direct and indirect evidence. It is far more difficult to decide what qualities determine the choice of the females; but here again we have some direct and indirect evidence that it is to a large extent the external attractions of the male; though no doubt his vigour, courage, and other mental qualities come into play. We will begin with the indirect evidence. LENGTH OF COURTSHIP. The lengthened period during which both sexes of certain birds meet day after day at an appointed place probably depends partly on the courtship being a prolonged affair, and partly on reiteration in the act of pairing. Thus in Germany and Scandinavia the balzen or leks of the black-cocks last from the middle of March, all through April into May. As many as forty or fifty, or even more birds congregate at the leks; and the same place is often frequented during successive years. The lek of the capercailzie lasts from the end of March to the middle or even end of May. In North America "the partridge dances" of the Tetrao phasianellus "last for a month or more." Other kinds of grouse, both in North America and Eastern Siberia (1. Nordman describes ('Bull. Soc. Imp. des Nat. Moscou,' 1861, tom. xxxiv. p. 264) the balzen of Tetrao urogalloides in Amur Land. He estimated the number of birds assembled at above a hundred, not counting the females, which lie hid in the surrounding bushes. The noises uttered differ from those of T. urogallus.), follow nearly the same habits. The fowlers discover the hillocks where the ruffs congregate by the grass being trampled bare, and this shews that the same spot is long frequented. The Indians of Guiana are well acquainted with the cleared arenas, where they expect to find the beautiful cocks of the Rock; and the natives of New Guinea know the trees where from ten to twenty male birds of paradise in full plumage congregate. In this latter case it is not expressly stated that the females meet on the same trees, but the hunters, if not specially asked, would probably not mention their presence, as their skins are valueless. Small parties of an African weaver (Ploceus) congregate, during the breeding-season, and perform for hours their graceful evolutions. Large numbers of the Solitary snipe (Scolopax major) assemble during dusk in a morass; and the same place is frequented for the same purpose during successive years; here they may be seen running about "like so many large rats," puffing out their feathers, flapping their wings, and uttering the strangest cries. (2. With respect to the assemblages of the above named grouse, see Brehm, 'Thierleben,' B. iv. s. 350; also L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 19, 78. Richardson, 'Fauna Bor. Americana: Birds,' p. 362. References in regard to the assemblages of other birds have already been given. On Paradisea, see Wallace, in 'Annals and Mag. of Nat. Hist.' vol. xx. 1857, p. 412. On the snipe, Lloyd, ibid. p. 221.) Some of the above birds,--the black-cock, capercailzie, pheasant-grouse, ruff, solitary snipe, and perhaps others,--are, as is believed, polygamists. With such birds it might have been thought that the stronger males would simply have driven away the weaker, and then at once have taken possession of as many females as possible; but if it be indispensable for the male to excite or please the female, we can understand the length of the courtship and the congregation of so many individuals of both sexes at the same spot. Certain strictly monogamous species likewise hold nuptial assemblages; this seems to be the case in Scandinavia with one of the ptarmigans, and their leks last from the middle of March to the middle of May. In Australia the lyre-bird (Menura superba) forms "small round hillocks," and the M. Alberti scratches for itself shallow holes, or, as they are called by the natives, "corroborying places," where it is believed both sexes assemble. The meetings of the M. superba are sometimes very large; and an account has lately been published (3. Quoted by Mr. T.W. Wood, in the 'Student,' April 1870, p. 125.) by a traveller, who heard in a valley beneath him, thickly covered with scrub, "a din which completely astonished" him; on crawling onwards he beheld, to his amazement, about one hundred and fifty of the magnificent lyre-cocks, "ranged in order of battle, and fighting with indescribable fury." The bowers of the Bower-birds are the resort of both sexes during the breeding-season; and "here the males meet and contend with each other for the favours of the female, and here the latter assemble and coquet with the males." With two of the genera, the same bower is resorted to during many years. (4. Gould, 'Handbook to the Birds of Australia,' vol. i. pp. 300, 308, 448, 451. On the ptarmigan, above alluded to, see Lloyd, ibid. p. 129.) The common magpie (Corvus pica, Linn.), as I have been informed by the Rev. W. Darwin Fox, used to assemble from all parts of Delamere Forest, in order to celebrate the "great magpie marriage." Some years ago these birds abounded in extraordinary numbers, so that a gamekeeper killed in one morning nineteen males, and another killed by a single shot seven birds at roost together. They then had the habit of assembling very early in the spring at particular spots, where they could be seen in flocks, chattering, sometimes fighting, bustling and flying about the trees. The whole affair was evidently considered by the birds as one of the highest importance. Shortly after the meeting they all separated, and were then observed by Mr. Fox and others to be paired for the season. In any district in which a species does not exist in large numbers, great assemblages cannot, of course, be held, and the same species may have different habits in different countries. For instance, I have heard of only one instance, from Mr. Wedderburn, of a regular assemblage of black game in Scotland, yet these assemblages are so well known in Germany and Scandinavia that they have received special names. UNPAIRED BIRDS. From the facts now given, we may conclude that the courtship of birds belonging to widely different groups, is often a prolonged, delicate, and troublesome affair. There is even reason to suspect, improbable as this will at first appear, that some males and females of the same species, inhabiting the same district, do not always please each other, and consequently do not pair. Many accounts have been published of either the male or female of a pair having been shot, and quickly replaced by another. This has been observed more frequently with the magpie than with any other bird, owing perhaps to its conspicuous appearance and nest. The illustrious Jenner states that in Wiltshire one of a pair was daily shot no less than seven times successively, "but all to no purpose, for the remaining magpie soon found another mate"; and the last pair reared their young. A new partner is generally found on the succeeding day; but Mr. Thompson gives the case of one being replaced on the evening of the same day. Even after the eggs are hatched, if one of the old birds is destroyed a mate will often be found; this occurred after an interval of two days, in a case recently observed by one of Sir J. Lubbock's keepers. (5. On magpies, Jenner, in 'Philosophical Transactions,' 1824, p. 21. Macgillivray, 'Hist. British Birds,' vol. i. p. 570. Thompson, in 'Annals and Magazine of Natural History,' vol. viii. 1842, p. 494.) The first and most obvious conjecture is that male magpies must be much more numerous than females; and that in the above cases, as well as in many others which could be given, the males alone had been killed. This apparently holds good in some instances, for the gamekeepers in Delamere Forest assured Mr. Fox that the magpies and carrion-crows which they formerly killed in succession in large numbers near their nests, were all males; and they accounted for this fact by the males being easily killed whilst bringing food to the sitting females. Macgillivray, however, gives, on the authority of an excellent observer, an instance of three magpies successively killed on the same nest, which were all females; and another case of six magpies successively killed whilst sitting on the same eggs, which renders it probable that most of them were females; though, as I hear from Mr. Fox, the male will sit on the eggs when the female is killed. Sir J. Lubbock's gamekeeper has repeatedly shot, but how often he could not say, one of a pair of jays (Garrulus glandarius), and has never failed shortly afterwards to find the survivor re-matched. Mr. Fox, Mr. F. Bond, and others have shot one of a pair of carrion-crows (Corvus corone), but the nest was soon again tenanted by a pair. These birds are rather common; but the peregrine-falcon (Falco peregrinus) is rare, yet Mr. Thompson states that in Ireland "if either an old male or female be killed in the breeding-season (not an uncommon circumstance), another mate is found within a very few days, so that the eyries, notwithstanding such casualties, are sure to turn out their complement of young." Mr. Jenner Weir has known the same thing with the peregrine-falcons at Beachy Head. The same observer informs me that three kestrels (Falco tinnunculus), all males, were killed one after the other whilst attending the same nest; two of these were in mature plumage, but the third was in the plumage of the previous year. Even with the rare golden eagle (Aquila chrysaetos), Mr. Birkbeck was assured by a trustworthy gamekeeper in Scotland, that if one is killed, another is soon found. So with the white owl (Strix flammea), "the survivor readily found a mate, and the mischief went on." White of Selborne, who gives the case of the owl, adds that he knew a man, who from believing that partridges when paired were disturbed by the males fighting, used to shoot them; and though he had widowed the same female several times, she always soon found a fresh partner. This same naturalist ordered the sparrows, which deprived the house-martins of their nests, to be shot; but the one which was left, "be it cock or hen, presently procured a mate, and so for several times following." I could add analogous cases relating to the chaffinch, nightingale, and redstart. With respect to the latter bird (Phoenicura ruticilla), a writer expresses much surprise how the sitting female could so soon have given effectual notice that she was a widow, for the species was not common in the neighbourhood. Mr. Jenner Weir has mentioned to me a nearly similar case; at Blackheath he never sees or hears the note of the wild bullfinch, yet when one of his caged males has died, a wild one in the course of a few days has generally come and perched near the widowed female, whose call-note is not loud. I will give only one other fact, on the authority of this same observer; one of a pair of starlings (Sturnus vulgaris) was shot in the morning; by noon a new mate was found; this was again shot, but before night the pair was complete; so that the disconsolate widow or widower was thrice consoled during the same day. Mr. Engleheart also informs me that he used during several years to shoot one of a pair of starlings which built in a hole in a house at Blackheath; but the loss was always immediately repaired. During one season he kept an account, and found that he had shot thirty-five birds from the same nest; these consisted of both males and females, but in what proportion he could not say: nevertheless, after all this destruction, a brood was reared. (6. On the peregrine falcon, see Thompson, 'Nat. Hist. of Ireland: Birds,' vol. i. 1849, p. 39. On owls, sparrows, and partridges, see White, 'Nat. Hist. of Selborne,' edit. of 1825, vol. i. p. 139. On the Phoenicura, see Loudon's 'Mag. of Nat. Hist.' vol. vii. 1834, p. 245. Brehm ('Thierleben,' B. iv. s. 991) also alludes to cases of birds thrice mated during the same day.) These facts well deserve attention. How is it that there are birds enough ready to replace immediately a lost mate of either sex? Magpies, jays, carrion-crows, partridges, and some other birds, are always seen during the spring in pairs, and never by themselves; and these offer at first sight the most perplexing cases. But birds of the same sex, although of course not truly paired, sometimes live in pairs or in small parties, as is known to be the case with pigeons and partridges. Birds also sometimes live in triplets, as has been observed with starlings, carrion-crows, parrots, and partridges. With partridges two females have been known to live with one male, and two males with one female. In all such cases it is probable that the union would be easily broken; and one of the three would readily pair with a widow or widower. The males of certain birds may occasionally be heard pouring forth their love-song long after the proper time, shewing that they have either lost or never gained a mate. Death from accident or disease of one of a pair would leave the other free and single; and there is reason to believe that female birds during the breeding-season are especially liable to premature death. Again, birds which have had their nests destroyed, or barren pairs, or retarded individuals, would easily be induced to desert their mates, and would probably be glad to take what share they could of the pleasures and duties of rearing offspring although not their own. (7. See White ('Nat. Hist. of Selborne,' 1825, vol. i. p. 140) on the existence, early in the season, of small coveys of male partridges, of which fact I have heard other instances. See Jenner, on the retarded state of the generative organs in certain birds, in 'Phil. Transact.' 1824. In regard to birds living in triplets, I owe to Mr. Jenner Weir the cases of the starlings and parrots, and to Mr. Fox, of partridges; on carrion-crows, see the 'Field,' 1868, p. 415. On various male birds singing after the proper period, see Rev. L. Jenyns, 'Observations in Natural History,' 1846, p. 87.) Such contingencies as these probably explain most of the foregoing cases. (8. The following case has been given ('The Times,' Aug. 6, 1868) by the Rev. F.O. Morris, on the authority of the Hon. and Rev. O.W. Forester. "The gamekeeper here found a hawk's nest this year, with five young ones on it. He took four and killed them, but left one with its wings clipped as a decoy to destroy the old ones by. They were both shot next day, in the act of feeding the young one, and the keeper thought it was done with. The next day he came again and found two other charitable hawks, who had come with an adopted feeling to succour the orphan. These two he killed, and then left the nest. On returning afterwards he found two more charitable individuals on the same errand of mercy. One of these he killed; the other he also shot, but could not find. No more came on the like fruitless errand.") Nevertheless, it is a strange fact that within the same district, during the height of the breeding-season, there should be so many males and females always ready to repair the loss of a mated bird. Why do not such spare birds immediately pair together? Have we not some reason to suspect, and the suspicion has occurred to Mr. Jenner Weir, that as the courtship of birds appears to be in many cases prolonged and tedious, so it occasionally happens that certain males and females do not succeed, during the proper season, in exciting each other's love, and consequently do not pair? This suspicion will appear somewhat less improbable after we have seen what strong antipathies and preferences female birds occasionally evince towards particular males. MENTAL QUALITIES OF BIRDS, AND THEIR TASTE FOR THE BEAUTIFUL. Before we further discuss the question whether the females select the more attractive males or accept the first whom they may encounter, it will be advisable briefly to consider the mental powers of birds. Their reason is generally, and perhaps justly, ranked as low; yet some facts could be given leading to an opposite conclusion. (9. I am indebted to Prof. Newton for the following passage from Mr. Adam's 'Travels of a Naturalist,' 1870, p. 278. Speaking of Japanese nut-hatches in confinement, he says: "Instead of the more yielding fruit of the yew, which is the usual food of the nut-hatch of Japan, at one time I substituted hard hazel-nuts. As the bird was unable to crack them, he placed them one by one in his water-glass, evidently with the notion that they would in time become softer--an interesting proof of intelligence on the part of these birds.") Low powers of reasoning, however, are compatible, as we see with mankind, with strong affections, acute perception, and a taste for the beautiful; and it is with these latter qualities that we are here concerned. It has often been said that parrots become so deeply attached to each other that when one dies the other pines for a long time; but Mr. Jenner Weir thinks that with most birds the strength of their affection has been much exaggerated. Nevertheless when one of a pair in a state of nature has been shot, the survivor has been heard for days afterwards uttering a plaintive call; and Mr. St. John gives various facts proving the attachment of mated birds. (10. 'A Tour in Sutherlandshire,' vol. i. 1849, p. 185. Dr. Buller says ('Birds of New Zealand,' 1872, p. 56) that a male King Lory was killed; and the female "fretted and moped, refused her food, and died of a broken heart.") Mr. Bennett relates (11. 'Wanderings in New South Wales,' vol. ii. 1834, p. 62.) that in China after a drake of the beautiful mandarin Teal had been stolen, the duck remained disconsolate, though sedulously courted by another mandarin drake, who displayed before her all his charms. After an interval of three weeks the stolen drake was recovered, and instantly the pair recognised each other with extreme joy. On the other hand, starlings, as we have seen, may be consoled thrice in the same day for the loss of their mates. Pigeons have such excellent local memories, that they have been known to return to their former homes after an interval of nine months, yet, as I hear from Mr. Harrison Weir, if a pair which naturally would remain mated for life be separated for a few weeks during the winter, and afterwards matched with other birds, the two when brought together again, rarely, if ever, recognise each other. Birds sometimes exhibit benevolent feelings; they will feed the deserted young ones even of distinct species, but this perhaps ought to be considered as a mistaken instinct. They will feed, as shewn in an earlier part of this work, adult birds of their own species which have become blind. Mr. Buxton gives a curious account of a parrot which took care of a frost-bitten and crippled bird of a distinct species, cleansed her feathers, and defended her from the attacks of the other parrots which roamed freely about his garden. It is a still more curious fact that these birds apparently evince some sympathy for the pleasures of their fellows. When a pair of cockatoos made a nest in an acacia tree, "it was ridiculous to see the extravagant interest taken in the matter by the others of the same species." These parrots, also, evinced unbounded curiosity, and clearly had "the idea of property and possession." (12. 'Acclimatization of Parrots,' by C. Buxton, M.P., 'Annals and Mag. of Nat. Hist.' Nov. 1868, p. 381.) They have good memories, for in the Zoological Gardens they have plainly recognised their former masters after an interval of some months. Birds possess acute powers of observation. Every mated bird, of course, recognises its fellow. Audubon states that a certain number of mocking-thrushes (Mimus polyglottus) remain all the year round in Louisiana, whilst others migrate to the Eastern States; these latter, on their return, are instantly recognised, and always attacked, by their southern brethren. Birds under confinement distinguish different persons, as is proved by the strong and permanent antipathy or affection which they shew, without any apparent cause, towards certain individuals. I have heard of numerous instances with jays, partridges, canaries, and especially bullfinches. Mr. Hussey has described in how extraordinary a manner a tamed partridge recognised everybody: and its likes and dislikes were very strong. This bird seemed "fond of gay colours, and no new gown or cap could be put on without catching his attention." (13. The 'Zoologist,' 1847-48, p. 1602.) Mr. Hewitt has described the habits of some ducks (recently descended from wild birds), which, at the approach of a strange dog or cat, would rush headlong into the water, and exhaust themselves in their attempts to escape; but they knew Mr. Hewitt's own dogs and cats so well that they would lie down and bask in the sun close to them. They always moved away from a strange man, and so they would from the lady who attended them if she made any great change in her dress. Audubon relates that he reared and tamed a wild turkey which always ran away from any strange dog; this bird escaped into the woods, and some days afterwards Audubon saw, as he thought, a wild turkey, and made his dog chase it; but, to his astonishment, the bird did not run away, and the dog, when he came up, did not attack the bird, for they mutually recognised each other as old friends. (14. Hewitt on wild ducks, 'Journal of Horticulture,' Jan. 13, 1863, p. 39. Audubon on the wild turkey, 'Ornithological Biography,' vol. i. p. 14. On the mocking-thrush, ibid. vol. i. p. 110.) Mr. Jenner Weir is convinced that birds pay particular attention to the colours of other birds, sometimes out of jealousy, and sometimes as a sign of kinship. Thus he turned a reed-bunting (Emberiza schoeniculus), which had acquired its black head-dress, into his aviary, and the new-comer was not noticed by any bird, except by a bullfinch, which is likewise black-headed. This bullfinch was a very quiet bird, and had never before quarrelled with any of its comrades, including another reed-bunting, which had not as yet become black-headed: but the reed-bunting with a black head was so unmercifully treated that it had to be removed. Spiza cyanea, during the breeding-season, is of a bright blue colour; and though generally peaceable, it attacked S. ciris, which has only the head blue, and completely scalped the unfortunate bird. Mr. Weir was also obliged to turn out a robin, as it fiercely attacked all the birds in his aviary with any red in their plumage, but no other kinds; it actually killed a red-breasted crossbill, and nearly killed a goldfinch. On the other hand, he has observed that some birds, when first introduced, fly towards the species which resemble them most in colour, and settle by their sides. As male birds display their fine plumage and other ornaments with so much care before the females, it is obviously probable that these appreciate the beauty of their suitors. It is, however, difficult to obtain direct evidence of their capacity to appreciate beauty. When birds gaze at themselves in a looking-glass (of which many instances have been recorded) we cannot feel sure that it is not from jealousy of a supposed rival, though this is not the conclusion of some observers. In other cases it is difficult to distinguish between mere curiosity and admiration. It is perhaps the former feeling which, as stated by Lord Lilford (15. The 'Ibis,' vol. ii. 1860, p. 344.), attracts the ruff towards any bright object, so that, in the Ionian Islands, "it will dart down to a bright-coloured handkerchief, regardless of repeated shots." The common lark is drawn down from the sky, and is caught in large numbers, by a small mirror made to move and glitter in the sun. Is it admiration or curiosity which leads the magpie, raven, and some other birds to steal and secrete bright objects, such as silver articles or jewels? Mr. Gould states that certain humming-birds decorate the outsides of their nests "with the utmost taste; they instinctively fasten thereon beautiful pieces of flat lichen, the larger pieces in the middle, and the smaller on the part attached to the branch. Now and then a pretty feather is intertwined or fastened to the outer sides, the stem being always so placed that the feather stands out beyond the surface." The best evidence, however, of a taste for the beautiful is afforded by the three genera of Australian bower-birds already mentioned. Their bowers (Fig. 46), where the sexes congregate and play strange antics, are variously constructed, but what most concerns us is, that they are decorated by the several species in a different manner. The Satin bower-bird collects gaily-coloured articles, such as the blue tail-feathers of parrakeets, bleached bones and shells, which it sticks between the twigs or arranges at the entrance. Mr. Gould found in one bower a neatly-worked stone tomahawk and a slip of blue cotton, evidently procured from a native encampment. These objects are continually re-arranged, and carried about by the birds whilst at play. The bower of the Spotted bower-bird "is beautifully lined with tall grasses, so disposed that the heads nearly meet, and the decorations are very profuse." Round stones are used to keep the grass-stems in their proper places, and to make divergent paths leading to the bower. The stones and shells are often brought from a great distance. The Regent bird, as described by Mr. Ramsay, ornaments its short bower with bleached land-shells belonging to five or six species, and with "berries of various colours, blue, red, and black, which give it when fresh a very pretty appearance. Besides these there were several newly-picked leaves and young shoots of a pinkish colour, the whole showing a decided taste for the beautiful." Well may Mr. Gould say that "these highly decorated halls of assembly must be regarded as the most wonderful instances of bird-architecture yet discovered;" and the taste, as we see, of the several species certainly differs. (16. On the ornamented nests of humming-birds, Gould, 'Introduction to the Trochilidae,' 1861, p. 19. On the bower-birds, Gould, 'Handbook to the Birds of Australia,' 1865, vol. i. pp. 444-461. Ramsay, in the 'Ibis,' 1867, p. 456.) PREFERENCE FOR PARTICULAR MALES BY THE FEMALES. Having made these preliminary remarks on the discrimination and taste of birds, I will give all the facts known to me which bear on the preference shewn by the female for particular males. It is certain that distinct species of birds occasionally pair in a state of nature and produce hybrids. Many instances could be given: thus Macgillivray relates how a male blackbird and female thrush "fell in love with each other," and produced offspring. (17. 'History of Brit. Birds,' vol. ii. p. 92.) Several years ago eighteen cases had been recorded of the occurrence in Great Britain of hybrids between the black grouse and pheasant (18. 'Zoologist,' 1853-1854, p. 3946.); but most of these cases may perhaps be accounted for by solitary birds not finding one of their own species to pair with. With other birds, as Mr. Jenner Weir has reason to believe, hybrids are sometimes the result of the casual intercourse of birds building in close proximity. But these remarks do not apply to the many recorded instances of tamed or domestic birds, belonging to distinct species, which have become absolutely fascinated with each other, although living with their own species. Thus Waterton (19. Waterton, 'Essays on Nat. Hist.' 2nd series, pp. 42 and 117. For the following statements see on the wigeon, 'Loudon's Mag. of Nat. Hist.' vol. ix. p. 616; L. Lloyd, 'Scandinavian Adventures,' vol. i. 1854, p. 452. Dixon, 'Ornamental and Domestic Poultry,' p. 137; Hewitt, in 'Journal of Horticulture,' Jan. 13, 1863, p. 40; Bechstein, 'Stubenvögel,' 1840, s. 230. Mr. J. Jenner Weir has lately given me an analogous case with ducks of two species.) states that out of a flock of twenty-three Canada geese, a female paired with a solitary Bernicle gander, although so different in appearance and size; and they produced hybrid offspring. A male wigeon (Mareca penelope), living with females of the same species, has been known to pair with a pintail duck, Querquedula acuta. Lloyd describes the remarkable attachment between a shield-drake (Tadorna vulpanser) and a common duck. Many additional instances could be given; and the Rev. E.S. Dixon remarks that "those who have kept many different species of geese together well know what unaccountable attachments they are frequently forming, and that they are quite as likely to pair and rear young with individuals of a race (species) apparently the most alien to themselves as with their own stock." The Rev. W.D. Fox informs me that he possessed at the same time a pair of Chinese geese (Anser cygnoides), and a common gander with three geese. The two lots kept quite separate, until the Chinese gander seduced one of the common geese to live with him. Moreover, of the young birds hatched from the eggs of the common geese, only four were pure, the other eighteen proving hybrids; so that the Chinese gander seems to have had prepotent charms over the common gander. I will give only one other case; Mr. Hewitt states that a wild duck, reared in captivity, "after breeding a couple of seasons with her own mallard, at once shook him off on my placing a male Pintail on the water. It was evidently a case of love at first sight, for she swam about the new-comer caressingly, though he appeared evidently alarmed and averse to her overtures of affection. From that hour she forgot her old partner. Winter passed by, and the next spring the pintail seemed to have become a convert to her blandishments, for they nested and produced seven or eight young ones." What the charm may have been in these several cases, beyond mere novelty, we cannot even conjecture. Colour, however, sometimes comes into play; for in order to raise hybrids from the siskin (Fringilla spinus) and the canary, it is much the best plan, according to Bechstein, to place birds of the same tint together. Mr. Jenner Weir turned a female canary into his aviary, where there were male linnets, goldfinches, siskins, greenfinches, chaffinches, and other birds, in order to see which she would choose; but there never was any doubt, and the greenfinch carried the day. They paired and produced hybrid offspring. The fact of the female preferring to pair with one male rather than with another of the same species is not so likely to excite attention, as when this occurs, as we have just seen, between distinct species. The former cases can best be observed with domesticated or confined birds; but these are often pampered by high feeding, and sometimes have their instincts vitiated to an extreme degree. Of this latter fact I could give sufficient proofs with pigeons, and especially with fowls, but they cannot be here related. Vitiated instincts may also account for some of the hybrid unions above mentioned; but in many of these cases the birds were allowed to range freely over large ponds, and there is no reason to suppose that they were unnaturally stimulated by high feeding. With respect to birds in a state of nature, the first and most obvious supposition which will occur to every one is that the female at the proper season accepts the first male whom she may encounter; but she has at least the opportunity for exerting a choice, as she is almost invariably pursued by many males. Audubon--and we must remember that he spent a long life in prowling about the forests of the United States and observing the birds--does not doubt that the female deliberately chooses her mate; thus, speaking of a woodpecker, he says the hen is followed by half-a-dozen gay suitors, who continue performing strange antics, "until a marked preference is shewn for one." The female of the red-winged starling (Agelaeus phoeniceus) is likewise pursued by several males, "until, becoming fatigued, she alights, receives their addresses, and soon makes a choice." He describes also how several male night-jars repeatedly plunge through the air with astonishing rapidity, suddenly turning, and thus making a singular noise; "but no sooner has the female made her choice than the other males are driven away." With one of the vultures (Cathartes aura) of the United States, parties of eight, ten, or more males and females assemble on fallen logs, "exhibiting the strongest desire to please mutually," and after many caresses, each male leads off his partner on the wing. Audubon likewise carefully observed the wild flocks of Canada geese (Anser canadensis), and gives a graphic description of their love-antics; he says that the birds which had been previously mated "renewed their courtship as early as the month of January, while the others would be contending or coquetting for hours every day, until all seemed satisfied with the choice they had made, after which, although they remained together, any person could easily perceive that they were careful to keep in pairs. I have observed also that the older the birds the shorter were the preliminaries of their courtship. The bachelors and old maids whether in regret, or not caring to be disturbed by the bustle, quietly moved aside and lay down at some distance from the rest." (20. Audubon, 'Ornithological Biography,' vol. i. pp. 191, 349; vol. ii. pp. 42, 275; vol. iii. p. 2.) Many similar statements with respect to other birds could be cited from this same observer. Turning now to domesticated and confined birds, I will commence by giving what little I have learnt respecting the courtship of fowls. I have received long letters on this subject from Messrs. Hewitt and Tegetmeier, and almost an essay from the late Mr. Brent. It will be admitted by every one that these gentlemen, so well known from their published works, are careful and experienced observers. They do not believe that the females prefer certain males on account of the beauty of their plumage; but some allowance must be made for the artificial state under which these birds have long been kept. Mr. Tegetmeier is convinced that a gamecock, though disfigured by being dubbed and with his hackles trimmed, would be accepted as readily as a male retaining all his natural ornaments. Mr. Brent, however, admits that the beauty of the male probably aids in exciting the female; and her acquiescence is necessary. Mr. Hewitt is convinced that the union is by no means left to mere chance, for the female almost invariably prefers the most vigorous, defiant, and mettlesome male; hence it is almost useless, as he remarks, "to attempt true breeding if a game-cock in good health and condition runs the locality, for almost every hen on leaving the roosting-place will resort to the game-cock, even though that bird may not actually drive away the male of her own variety." Under ordinary circumstances the males and females of the fowl seem to come to a mutual understanding by means of certain gestures, described to me by Mr. Brent. But hens will often avoid the officious attentions of young males. Old hens, and hens of a pugnacious disposition, as the same writer informs me, dislike strange males, and will not yield until well beaten into compliance. Ferguson, however, describes how a quarrelsome hen was subdued by the gentle courtship of a Shanghai cock. (21. 'Rare and Prize Poultry,' 1854, p. 27.) There is reason to believe that pigeons of both sexes prefer pairing with birds of the same breed; and dovecot-pigeons dislike all the highly improved breeds. (22. 'Variation of Animals and Plants under Domestication,' vol. ii. p. 103.) Mr. Harrison Weir has lately heard from a trustworthy observer, who keeps blue pigeons, that these drive away all other coloured varieties, such as white, red, and yellow; and from another observer, that a female dun carrier could not, after repeated trials, be matched with a black male, but immediately paired with a dun. Again, Mr. Tegetmeier had a female blue turbit that obstinately refused to pair with two males of the same breed, which were successively shut up with her for weeks; but on being let out she would have immediately accepted the first blue dragon that offered. As she was a valuable bird, she was then shut up for many weeks with a silver (i.e., very pale blue) male, and at last mated with him. Nevertheless, as a general rule, colour appears to have little influence on the pairing of pigeons. Mr. Tegetmeier, at my request, stained some of his birds with magenta, but they were not much noticed by the others. Female pigeons occasionally feel a strong antipathy towards certain males, without any assignable cause. Thus MM. Boitard and Corbie, whose experience extended over forty-five years, state: "Quand une femelle éprouve de l'antipathie pour un mâle avec lequel on veut l'accoupler, malgré tous les feux de l'amour, malgré l'alpiste et le chenevis dont on la nourrit pour augmenter son ardeur, malgré un emprisonnement de six mois et même d'un an, elle refuse constamment ses caresses; les avances empressées, les agaceries, les tournoiemens, les tendres roucoulemens, rien ne peut lui plaire ni l'émouvoir; gonflée, boudeuse, blottie dans un coin de sa prison, elle n'en sort que pour boire et manger, ou pour repousser avec une espèce de rage des caresses devenues trop pressantes." (23. Boitard and Corbie, 'Les Pigeons,' etc., 1824, p. 12. Prosper Lucas ('Traité de l'Héréd. Nat.' tom. ii. 1850, p. 296) has himself observed nearly similar facts with pigeons.) On the other hand, Mr. Harrison Weir has himself observed, and has heard from several breeders, that a female pigeon will occasionally take a strong fancy for a particular male, and will desert her own mate for him. Some females, according to another experienced observer, Riedel (24. Die Taubenzucht, 1824, s. 86.), are of a profligate disposition, and prefer almost any stranger to their own mate. Some amorous males, called by our English fanciers "gay birds," are so successful in their gallantries, that, as Mr. H. Weir informs me, they must be shut up on account of the mischief which they cause. Wild turkeys in the United States, according to Audubon, "sometimes pay their addresses to the domesticated females, and are generally received by them with great pleasure." So that these females apparently prefer the wild to their own males. (25. 'Ornithological Biography,' vol. i. p. 13. See to the same effect, Dr. Bryant, in Allen's 'Mammals and Birds of Florida,' p. 344.) Here is a more curious case. Sir R. Heron during many years kept an account of the habits of the peafowl, which he bred in large numbers. He states that "the hens have frequently great preference to a particular peafowl. They were all so fond of an old pied cock, that one year, when he was confined, though still in view, they were constantly assembled close to the trellice-walls of his prison, and would not suffer a japanned peacock to touch them. On his being let out in the autumn, the oldest of the hens instantly courted him and was successful in her courtship. The next year he was shut up in a stable, and then the hens all courted his rival." (26. 'Proceedings, Zoological Society,' 1835, p. 54. The japanned peacock is considered by Mr. Sclater as a distinct species, and has been named Pavo nigripennis; but the evidence seems to me to show that it is only a variety.) This rival was a japanned or black-winged peacock, to our eyes a more beautiful bird than the common kind. Lichtenstein, who was a good observer and had excellent opportunities of observation at the Cape of Good Hope, assured Rudolphi that the female widow-bird (Chera progne) disowns the male when robbed of the long tail-feathers with which he is ornamented during the breeding-season. I presume that this observation must have been made on birds under confinement. (27. Rudolphi, 'Beiträge zur Anthropologie,' 1812, s. 184.) Here is an analogous case; Dr. Jaeger (28. 'Die Darwin'sche Theorie, und ihre Stellung zu Moral und Religion,' 1869, s. 59.), director of the Zoological Gardens of Vienna, states that a male silver-pheasant, who had been triumphant over all other males and was the accepted lover of the females, had his ornamental plumage spoiled. He was then immediately superseded by a rival, who got the upper hand and afterwards led the flock. It is a remarkable fact, as shewing how important colour is in the courtship of birds, that Mr. Boardman, a well-known collector and observer of birds for many years in the Northern United States, has never in his large experience seen an albino paired with another bird; yet he has had opportunities of observing many albinos belonging to several species. (29. This statement is given by Mr. A. Leith Adams, in his 'Field and Forest Rambles,' 1873, p. 76, and accords with his own experience.) It can hardly be maintained that albinos in a state of nature are incapable of breeding, as they can be raised with the greatest facility under confinement. It appears, therefore, that we must attribute the fact that they do not pair to their rejection by their normally coloured comrades. Female birds not only exert a choice, but in some few cases they court the male, or even fight together for his possession. Sir R. Heron states that with peafowl, the first advances are always made by the female; something of the same kind takes place, according to Audubon, with the older females of the wild turkey. With the capercailzie, the females flit round the male whilst he is parading at one of the places of assemblage, and solicit his attention. (30. In regard to peafowl, see Sir R. Heron, 'Proc. Zoolog. Soc.' 1835, p. 54, and the Rev. E.S. Dixon, 'Ornamental Poultry,' 1848, p. 8. For the turkey, Audubon, ibid. p. 4. For the capercailzie, Lloyd, 'Game Birds of Sweden,' 1867, p. 23.) We have seen that a tame wild-duck seduced an unwilling pintail drake after a long courtship. Mr. Bartlett believes that the Lophophorus, like many other gallinaceous birds, is naturally polygamous, but two females cannot be placed in the same cage with a male, as they fight so much together. The following instance of rivalry is more surprising as it relates to bullfinches, which usually pair for life. Mr. Jenner Weir introduced a dull-coloured and ugly female into his aviary, and she immediately attacked another mated female so unmercifully that the latter had to be separated. The new female did all the courtship, and was at last successful, for she paired with the male; but after a time she met with a just retribution, for, ceasing to be pugnacious, she was replaced by the old female, and the male then deserted his new and returned to his old love. In all ordinary cases the male is so eager that he will accept any female, and does not, as far as we can judge, prefer one to the other; but, as we shall hereafter see, exceptions to this rule apparently occur in some few groups. With domesticated birds, I have heard of only one case of males shewing any preference for certain females, namely, that of the domestic cock, who, according to the high authority of Mr. Hewitt, prefers the younger to the older hens. On the other hand, in effecting hybrid unions between the male pheasant and common hens, Mr. Hewitt is convinced that the pheasant invariably prefers the older birds. He does not appear to be in the least influenced by their colour; but "is most capricious in his attachments" (31. Mr. Hewitt, quoted in Tegetmeier's 'Poultry Book,' 1866, p. 165.): from some inexplicable cause he shews the most determined aversion to certain hens, which no care on the part of the breeder can overcome. Mr. Hewitt informs me that some hens are quite unattractive even to the males of their own species, so that they may be kept with several cocks during a whole season, and not one egg out of forty or fifty will prove fertile. On the other hand, with the long-tailed duck (Harelda glacialis), "it has been remarked," says M. Ekstrom, "that certain females are much more courted than the rest. Frequently, indeed, one sees an individual surrounded by six or eight amorous males." Whether this statement is credible, I know not; but the native sportsmen shoot these females in order to stuff them as decoys. (32. Quoted in Lloyd's 'Game Birds of Sweden,' p. 345.) With respect to female birds feeling a preference for particular males, we must bear in mind that we can judge of choice being exerted only by analogy. If an inhabitant of another planet were to behold a number of young rustics at a fair courting a pretty girl, and quarrelling about her like birds at one of their places of assemblage, he would, by the eagerness of the wooers to please her and to display their finery, infer that she had the power of choice. Now with birds the evidence stands thus: they have acute powers of observation, and they seem to have some taste for the beautiful both in colour and sound. It is certain that the females occasionally exhibit, from unknown causes, the strongest antipathies and preferences for particular males. When the sexes differ in colour or in other ornaments the males with rare exceptions are the more decorated, either permanently or temporarily during the breeding-season. They sedulously display their various ornaments, exert their voices, and perform strange antics in the presence of the females. Even well-armed males, who, it might be thought, would altogether depend for success on the law of battle, are in most cases highly ornamented; and their ornaments have been acquired at the expense of some loss of power. In other cases ornaments have been acquired, at the cost of increased risk from birds and beasts of prey. With various species many individuals of both sexes congregate at the same spot, and their courtship is a prolonged affair. There is even reason to suspect that the males and females within the same district do not always succeed in pleasing each other and pairing. What then are we to conclude from these facts and considerations? Does the male parade his charms with so much pomp and rivalry for no purpose? Are we not justified in believing that the female exerts a choice, and that she receives the addresses of the male who pleases her most? It is not probable that she consciously deliberates; but she is most excited or attracted by the most beautiful, or melodious, or gallant males. Nor need it be supposed that the female studies each stripe or spot of colour; that the peahen, for instance, admires each detail in the gorgeous train of the peacock--she is probably struck only by the general effect. Nevertheless, after hearing how carefully the male Argus pheasant displays his elegant primary wing-feathers, and erects his ocellated plumes in the right position for their full effect; or again, how the male goldfinch alternately displays his gold-bespangled wings, we ought not to feel too sure that the female does not attend to each detail of beauty. We can judge, as already remarked, of choice being exerted, only from analogy; and the mental powers of birds do not differ fundamentally from ours. From these various considerations we may conclude that the pairing of birds is not left to chance; but that those males, which are best able by their various charms to please or excite the female, are under ordinary circumstances accepted. If this be admitted, there is not much difficulty in understanding how male birds have gradually acquired their ornamental characters. All animals present individual differences, and as man can modify his domesticated birds by selecting the individuals which appear to him the most beautiful, so the habitual or even occasional preference by the female of the more attractive males would almost certainly lead to their modification; and such modifications might in the course of time be augmented to almost any extent, compatible with the existence of the species. VARIABILITY OF BIRDS, AND ESPECIALLY OF THEIR SECONDARY SEXUAL CHARACTERS. Variability and inheritance are the foundations for the work of selection. That domesticated birds have varied greatly, their variations being inherited, is certain. That birds in a state of nature have been modified into distinct races is now universally admitted. (33. According to Dr. Blasius ('Ibis,' vol. ii. 1860, p. 297), there are 425 indubitable species of birds which breed in Europe, besides sixty forms, which are frequently regarded as distinct species. Of the latter, Blasius thinks that only ten are really doubtful, and that the other fifty ought to be united with their nearest allies; but this shews that there must be a considerable amount of variation with some of our European birds. It is also an unsettled point with naturalists, whether several North American birds ought to be ranked as specifically distinct from the corresponding European species. So again many North American forms which until lately were named as distinct species, are now considered to be local races.) Variations may be divided into two classes; those which appear to our ignorance to arise spontaneously, and those which are directly related to the surrounding conditions, so that all or nearly all the individuals of the same species are similarly modified. Cases of the latter kind have recently been observed with care by Mr. J.A. Allen (34. 'Mammals and Birds of East Florida,' also an 'Ornithological Reconnaissance of Kansas,' etc. Notwithstanding the influence of climate on the colours of birds, it is difficult to account for the dull or dark tints of almost all the species inhabiting certain countries, for instance, the Galapagos Islands under the equator, the wide temperate plains of Patagonia, and, as it appears, Egypt (see Mr. Hartshorne in the 'American Naturalist,' 1873, p. 747). These countries are open, and afford little shelter to birds; but it seems doubtful whether the absence of brightly coloured species can be explained on the principle of protection, for on the Pampas, which are equally open, though covered by green grass, and where the birds would be equally exposed to danger, many brilliant and conspicuously coloured species are common. I have sometimes speculated whether the prevailing dull tints of the scenery in the above named countries may not have affected the appreciation of bright colours by the birds inhabiting them.), who shews that in the United States many species of birds gradually become more strongly coloured in proceeding southward, and more lightly coloured in proceeding westward to the arid plains of the interior. Both sexes seem generally to be affected in a like manner, but sometimes one sex more than the other. This result is not incompatible with the belief that the colours of birds are mainly due to the accumulation of successive variations through sexual selection; for even after the sexes have been greatly differentiated, climate might produce an equal effect on both sexes, or a greater effect on one sex than on the other, owing to some constitutional difference. Individual differences between the members of the same species are admitted by every one to occur under a state of nature. Sudden and strongly marked variations are rare; it is also doubtful whether if beneficial they would often be preserved through selection and transmitted to succeeding generations. (35. 'Origin of Species' fifth edit. 1869, p.104. I had always perceived, that rare and strongly-marked deviations of structure, deserving to be called monstrosities, could seldom be preserved through natural selection, and that the preservation of even highly-beneficial variations would depend to a certain extent on chance. I had also fully appreciated the importance of mere individual differences, and this led me to insist so strongly on the importance of that unconscious form of selection by man, which follows from the preservation of the most valued individuals of each breed, without any intention on his part to modify the characters of the breed. But until I read an able article in the 'North British Review' (March 1867, p. 289, et seq.), which has been of more use to me than any other Review, I did not see how great the chances were against the preservation of variations, whether slight or strongly pronounced, occurring only in single individuals.) Nevertheless, it may be worth while to give the few cases which I have been able to collect, relating chiefly to colour,--simple albinism and melanism being excluded. Mr. Gould is well known to admit the existence of few varieties, for he esteems very slight differences as specific; yet he states (36. 'Introduction to the Trochlidae,' p. 102.) that near Bogota certain humming-birds belonging to the genus Cynanthus are divided into two or three races or varieties, which differ from each other in the colouring of the tail--"some having the whole of the feathers blue, while others have the eight central ones tipped with beautiful green." It does not appear that intermediate gradations have been observed in this or the following cases. In the males alone of one of the Australian parrakeets "the thighs in some are scarlet, in others grass-green." In another parrakeet of the same country "some individuals have the band across the wing-coverts bright-yellow, while in others the same part is tinged with red." (37. Gould, 'Handbook to Birds of Australia,' vol. ii. pp. 32 and 68.) In the United States some few of the males of the scarlet tanager (Tanagra rubra) have "a beautiful transverse band of glowing red on the smaller wing-coverts" (38. Audubon, 'Ornithological Biography,' 1838, vol. iv. p. 389.); but this variation seems to be somewhat rare, so that its preservation through sexual selection would follow only under usually favourable circumstances. In Bengal the Honey buzzard (Pernis cristata) has either a small rudimental crest on its head, or none at all: so slight a difference, however, would not have been worth notice, had not this same species possessed in Southern India a well-marked occipital crest formed of several graduated feathers." (39. Jerdon, 'Birds of India,' vol. i. p. 108; and Mr. Blyth, in 'Land and Water,' 1868, p. 381.) The following case is in some respects more interesting. A pied variety of the raven, with the head, breast, abdomen, and parts of the wings and tail-feathers white, is confined to the Feroe Islands. It is not very rare there, for Graba saw during his visit from eight to ten living specimens. Although the characters of this variety are not quite constant, yet it has been named by several distinguished ornithologists as a distinct species. The fact of the pied birds being pursued and persecuted with much clamour by the other ravens of the island was the chief cause which led Brunnich to conclude that they were specifically distinct; but this is now known to be an error. (40. Graba, 'Tagebuch Reise nach Faro,' 1830, ss. 51-54. Macgillivray, 'History of British Birds,' vol. iii. p. 745, 'Ibis,' vol. v. 1863, p. 469.) This case seems analogous to that lately given of albino birds not pairing from being rejected by their comrades. In various parts of the northern seas a remarkable variety of the common Guillemot (Uria troile) is found; and in Feroe, one out of every five birds, according to Graba's estimation, presents this variation. It is characterised (41. Graba, ibid. s. 54. Macgillivray, ibid. vol. v. p. 327.) by a pure white ring round the eye, with a curved narrow white line, an inch and a half in length, extending back from the ring. This conspicuous character has caused the bird to be ranked by several ornithologists as a distinct species under the name of U. lacrymans, but it is now known to be merely a variety. It often pairs with the common kind, yet intermediate gradations have never been seen; nor is this surprising, for variations which appear suddenly, are often, as I have elsewhere shewn (42. 'Variation of Animals and Plants under Domestication,' vol. ii. p. 92.), transmitted either unaltered or not at all. We thus see that two distinct forms of the same species may co-exist in the same district, and we cannot doubt that if the one had possessed any advantage over the other, it would soon have been multiplied to the exclusion of the latter. If, for instance, the male pied ravens, instead of being persecuted by their comrades, had been highly attractive (like the above pied peacock) to the black female ravens their numbers would have rapidly increased. And this would have been a case of sexual selection. With respect to the slight individual differences which are common, in a greater or less degree, to all the members of the same species, we have every reason to believe that they are by far the most important for the work of selection. Secondary sexual characters are eminently liable to vary, both with animals in a state of nature and under domestication. (43. On these points see also 'Variation of Animals and Plants under Domestication,' vol. i. p. 253; vol ii. pp. 73, 75.) There is also reason to believe, as we have seen in our eighth chapter, that variations are more apt to occur in the male than in the female sex. All these contingencies are highly favourable for sexual selection. Whether characters thus acquired are transmitted to one sex or to both sexes, depends, as we shall see in the following chapter, on the form of inheritance which prevails. It is sometimes difficult to form an opinion whether certain slight differences between the sexes of birds are simply the result of variability with sexually-limited inheritance, without the aid of sexual selection, or whether they have been augmented through this latter process. I do not here refer to the many instances where the male displays splendid colours or other ornaments, of which the female partakes to a slight degree; for these are almost certainly due to characters primarily acquired by the male having been more or less transferred to the female. But what are we to conclude with respect to certain birds in which, for instance, the eyes differ slightly in colour in the two sexes? (44. See, for instance, on the irides of a Podica and Gallicrex in 'Ibis,' vol. ii. 1860, p. 206; and vol. v. 1863, p. 426.) In some cases the eyes differ conspicuously; thus with the storks of the genus Xenorhynchus, those of the male are blackish-hazel, whilst those of the females are gamboge-yellow; with many hornbills (Buceros), as I hear from Mr. Blyth (45. See also Jerdon, 'Birds of India,' vol. i. pp. 243-245.), the males have intense crimson eyes, and those of the females are white. In the Buceros bicornis, the hind margin of the casque and a stripe on the crest of the beak are black in the male, but not so in the female. Are we to suppose that these black marks and the crimson colour of the eyes have been preserved or augmented through sexual selection in the males? This is very doubtful; for Mr. Bartlett shewed me in the Zoological Gardens that the inside of the mouth of this Buceros is black in the male and flesh-coloured in the female; and their external appearance or beauty would not be thus affected. I observed in Chile (46. 'Zoology of the Voyage of H.M.S. "Beagle,"' 1841, p. 6.) that the iris in the condor, when about a year old, is dark-brown, but changes at maturity into yellowish-brown in the male, and into bright red in the female. The male has also a small, longitudinal, leaden-coloured, fleshy crest or comb. The comb of many gallinaceous birds is highly ornamental, and assumes vivid colours during the act of courtship; but what are we to think of the dull-coloured comb of the condor, which does not appear to us in the least ornamental? The same question may be asked in regard to various other characters, such as the knob on the base of the beak of the Chinese goose (Anser cygnoides), which is much larger in the male than in the female. No certain answer can be given to these questions; but we ought to be cautious in assuming that knobs and various fleshy appendages cannot be attractive to the female, when we remember that with savage races of man various hideous deformities--deep scars on the face with the flesh raised into protuberances, the septum of the nose pierced by sticks or bones, holes in the ears and lips stretched widely open--are all admired as ornamental. Whether or not unimportant differences between the sexes, such as those just specified, have been preserved through sexual selection, these differences, as well as all others, must primarily depend on the laws of variation. On the principle of correlated development, the plumage often varies on different parts of the body, or over the whole body, in the same manner. We see this well illustrated in certain breeds of the fowl. In all the breeds the feathers on the neck and loins of the males are elongated, and are called hackles; now when both sexes acquire a top-knot, which is a new character in the genus, the feathers on the head of the male become hackle-shaped, evidently on the principle of correlation; whilst those on the head of the female are of the ordinary shape. The colour also of the hackles forming the top-knot of the male, is often correlated with that of the hackles on the neck and loins, as may be seen by comparing these feathers in the golden and silver-spangled Polish, the Houdans, and Creve-coeur breeds. In some natural species we may observe exactly the same correlation in the colours of these same feathers, as in the males of the splendid Gold and Amherst pheasants. The structure of each individual feather generally causes any change in its colouring to be symmetrical; we see this in the various laced, spangled, and pencilled breeds of the fowl; and on the principle of correlation the feathers over the whole body are often coloured in the same manner. We are thus enabled without much trouble to rear breeds with their plumage marked almost as symmetrically as in natural species. In laced and spangled fowls the coloured margins of the feathers are abruptly defined; but in a mongrel raised by me from a black Spanish cock glossed with green, and a white game-hen, all the feathers were greenish-black, excepting towards their extremities, which were yellowish-white; but between the white extremities and the black bases, there was on each feather a symmetrical, curved zone of dark-brown. In some instances the shaft of the feather determines the distribution of the tints; thus with the body-feathers of a mongrel from the same black Spanish cock and a silver-spangled Polish hen, the shaft, together with a narrow space on each side, was greenish-black, and this was surrounded by a regular zone of dark-brown, edged with brownish-white. In these cases we have feathers symmetrically shaded, like those which give so much elegance to the plumage of many natural species. I have also noticed a variety of the common pigeon with the wing-bars symmetrically zoned with three bright shades, instead of being simply black on a slaty-blue ground, as in the parent-species. In many groups of birds the plumage is differently coloured in the several species, yet certain spots, marks, or stripes are retained by all. Analogous cases occur with the breeds of the pigeon, which usually retain the two wing-bars, though they may be coloured red, yellow, white, black, or blue, the rest of the plumage being of some wholly different tint. Here is a more curious case, in which certain marks are retained, though coloured in a manner almost exactly the opposite of what is natural; the aboriginal pigeon has a blue tail, with the terminal halves of the outer webs of the two outer tail feathers white; now there is a sub-variety having a white instead of a blue tail, with precisely that part black which is white in the parent-species. (47. Bechstein, 'Naturgeschichte Deutschlands,' B. iv. 1795, s. 31, on a sub-variety of the Monck pigeon.) FORMATION AND VARIABILITY OF THE OCELLI OR EYE-LIKE SPOTS ON THE PLUMAGE OF BIRDS. [Fig. 53. Cyllo leda, Linn., from a drawing by Mr. Trimen, shewing the extreme range of variation in the ocelli. A. Specimen, from Mauritius, upper surface of fore-wing. A1. Specimen, from Natal, ditto. B. Specimen, from Java, upper surface of hind-wing. B1. Specimen, from Mauritius, ditto.] As no ornaments are more beautiful than the ocelli on the feathers of various birds, on the hairy coats of some mammals, on the scales of reptiles and fishes, on the skin of amphibians, on the wings of many Lepidoptera and other insects, they deserve to be especially noticed. An ocellus consists of a spot within a ring of another colour, like the pupil within the iris, but the central spot is often surrounded by additional concentric zones. The ocelli on the tail-coverts of the peacock offer a familiar example, as well as those on the wings of the peacock-butterfly (Vanessa). Mr. Trimen has given me a description of a S. African moth (Gynanisa isis), allied to our Emperor moth, in which a magnificent ocellus occupies nearly the whole surface of each hinder wing; it consists of a black centre, including a semi-transparent crescent-shaped mark, surrounded by successive, ochre-yellow, black, ochre-yellow, pink, white, pink, brown, and whitish zones. Although we do not know the steps by which these wonderfully beautiful and complex ornaments have been developed, the process has probably been a simple one, at least with insects; for, as Mr. Trimen writes to me, "no characters of mere marking or coloration are so unstable in the Lepidoptera as the ocelli, both in number and size." Mr. Wallace, who first called my attention to this subject, shewed me a series of specimens of our common meadow-brown butterfly (Hipparchia janira) exhibiting numerous gradations from a simple minute black spot to an elegantly-shaded ocellus. In a S. African butterfly (Cyllo leda, Linn.), belonging to the same family, the ocelli are even still more variable. In some specimens (A, Fig. 53) large spaces on the upper surface of the wings are coloured black, and include irregular white marks; and from this state a complete gradation can be traced into a tolerably perfect ocellus (A1), and this results from the contraction of the irregular blotches of colour. In another series of specimens a gradation can be followed from excessively minute white dots, surrounded by a scarcely visible black line (B), into perfectly symmetrical and large ocelli (B1). (48. This woodcut has been engraved from a beautiful drawing, most kindly made for me by Mr. Trimen; see also his description of the wonderful amount of variation in the coloration and shape of the wings of this butterfly, in his 'Rhopalocera Africae Australis,' p. 186.) In cases like these, the development of a perfect ocellus does not require a long course of variation and selection. With birds and many other animals, it seems to follow from the comparison of allied species that circular spots are often generated by the breaking up and contraction of stripes. In the Tragopan pheasant faint white lines in the female represent the beautiful white spots in the male (49. Jerdon, 'Birds of India,' vol. iii. p. 517.); and something of the same kind may be observed in the two sexes of the Argus pheasant. However this may be, appearances strongly favour the belief that on the one hand, a dark spot is often formed by the colouring matter being drawn towards a central point from a surrounding zone, which latter is thus rendered lighter; and, on the other hand, that a white spot is often formed by the colour being driven away from a central point, so that it accumulates in a surrounding darker zone. In either case an ocellus is the result. The colouring matter seems to be a nearly constant quantity, but is redistributed, either centripetally or centrifugally. The feathers of the common guinea-fowl offer a good instance of white spots surrounded by darker zones; and wherever the white spots are large and stand near each other, the surrounding dark zones become confluent. In the same wing-feather of the Argus pheasant dark spots may be seen surrounded by a pale zone, and white spots by a dark zone. Thus the formation of an ocellus in its most elementary state appears to be a simple affair. By what further steps the more complex ocelli, which are surrounded by many successive zones of colour, have been generated, I will not pretend to say. But the zoned feathers of the mongrels from differently coloured fowls, and the extraordinary variability of the ocelli on many Lepidoptera, lead us to conclude that their formation is not a complex process, but depends on some slight and graduated change in the nature of the adjoining tissues. GRADATION OF SECONDARY SEXUAL CHARACTERS. [Fig. 54. Feather of Peacock, about two-thirds of natural size, drawn by Mr. Ford. The transparent zone is represented by the outermost white zone, confined to the upper end of the disc.] Cases of gradation are important, as shewing us that highly complex ornaments may be acquired by small successive steps. In order to discover the actual steps by which the male of any existing bird has acquired his magnificent colours or other ornaments, we ought to behold the long line of his extinct progenitors; but this is obviously impossible. We may, however, generally gain a clue by comparing all the species of the same group, if it be a large one; for some of them will probably retain, at least partially, traces of their former characters. Instead of entering on tedious details respecting various groups, in which striking instances of gradation could be given, it seems the best plan to take one or two strongly marked cases, for instance that of the peacock, in order to see if light can be thrown on the steps by which this bird has become so splendidly decorated. The peacock is chiefly remarkable from the extraordinary length of his tail-coverts; the tail itself not being much elongated. The barbs along nearly the whole length of these feathers stand separate or are decomposed; but this is the case with the feathers of many species, and with some varieties of the domestic fowl and pigeon. The barbs coalesce towards the extremity of the shaft forming the oval disc or ocellus, which is certainly one of the most beautiful objects in the world. It consists of an iridescent, intensely blue, indented centre, surrounded by a rich green zone, this by a broad coppery-brown zone, and this by five other narrow zones of slightly different iridescent shades. A trifling character in the disc deserves notice; the barbs, for a space along one of the concentric zones are more or less destitute of their barbules, so that a part of the disc is surrounded by an almost transparent zone, which gives it a highly finished aspect. But I have elsewhere described (50. 'Variation of Animals and Plants under Domestication,' vol. i. p. 254.) an exactly analogous variation in the hackles of a sub-variety of the game-cock, in which the tips, having a metallic lustre, "are separated from the lower part of the feather by a symmetrically shaped transparent zone, composed of the naked portions of the barbs." The lower margin or base of the dark-blue centre of the ocellus is deeply indented on the line of the shaft. The surrounding zones likewise shew traces, as may be seen in the drawing (Fig. 54), of indentations, or rather breaks. These indentations are common to the Indian and Javan peacocks (Pavo cristatus and P. muticus); and they seem to deserve particular attention, as probably connected with the development of the ocellus; but for a long time I could not conjecture their meaning. If we admit the principle of gradual evolution, there must formerly have existed many species which presented every successive step between the wonderfully elongated tail-coverts of the peacock and the short tail-coverts of all ordinary birds; and again between the magnificent ocelli of the former, and the simpler ocelli or mere coloured spots on other birds; and so with all the other characters of the peacock. Let us look to the allied Gallinaceae for any still-existing gradations. The species and sub-species of Polyplectron inhabit countries adjacent to the native land of the peacock; and they so far resemble this bird that they are sometimes called peacock-pheasants. I am also informed by Mr. Bartlett that they resemble the peacock in their voice and in some of their habits. During the spring the males, as previously described, strut about before the comparatively plain-coloured females, expanding and erecting their tail and wing-feathers, which are ornamented with numerous ocelli. I request the reader to turn back to the drawing (Fig. 51) of a Polyplectron; In P. napoleonis the ocelli are confined to the tail, and the back is of a rich metallic blue; in which respects this species approaches the Java peacock. P. hardwickii possesses a peculiar top-knot, which is also somewhat like that of the Java peacock. In all the species the ocelli on the wings and tail are either circular or oval, and consist of a beautiful, iridescent, greenish-blue or greenish-purple disc, with a black border. This border in P. chinquis shades into brown, edged with cream colour, so that the ocellus is here surrounded with variously shaded, though not bright, concentric zones. The unusual length of the tail-coverts is another remarkable character in Polyplectron; for in some of the species they are half, and in others two-thirds as long as the true tail-feathers. The tail-coverts are ocellated as in the peacock. Thus the several species of Polyplectron manifestly make a graduated approach to the peacock in the length of their tail-coverts, in the zoning of the ocelli, and in some other characters. [Fig. 55. Part of a tail-covert of Polyplectron chinquis, with the two ocelli of natural size. Fig. 56. Part of a tail-covert of Polyplectron malaccense, with the two ocelli, partially confluent, of natural size.] Notwithstanding this approach, the first species of Polyplectron which I examined almost made me give up the search; for I found not only that the true tail-feathers, which in the peacock are quite plain, were ornamented with ocelli, but that the ocelli on all the feathers differed fundamentally from those of the peacock, in there being two on the same feather (Fig. 55), one on each side of the shaft. Hence I concluded that the early progenitors of the peacock could not have resembled a Polyplectron. But on continuing my search, I observed that in some of the species the two ocelli stood very near each other; that in the tail-feathers of P. hardwickii they touched each other; and, finally, that on the tail-coverts of this same species as well as of P. malaccense (Fig. 56) they were actually confluent. As the central part alone is confluent, an indentation is left at both the upper and lower ends; and the surrounding coloured zones are likewise indented. A single ocellus is thus formed on each tail-covert, though still plainly betraying its double origin. These confluent ocelli differ from the single ocelli of the peacock in having an indentation at both ends, instead of only at the lower or basal end. The explanation, however, of this difference is not difficult; in some species of Polyplectron the two oval ocelli on the same feather stand parallel to each other; in other species (as in P. chinquis) they converge towards one end; now the partial confluence of two convergent ocelli would manifestly leave a much deeper indentation at the divergent than at the convergent end. It is also manifest that if the convergence were strongly pronounced and the confluence complete, the indentation at the convergent end would tend to disappear. The tail-feathers in both species of the peacock are entirely destitute of ocelli, and this apparently is related to their being covered up and concealed by the long tail-coverts. In this respect they differ remarkably from the tail-feathers of Polyplectron, which in most of the species are ornamented with larger ocelli than those on the tail-coverts. Hence I was led carefully to examine the tail-feathers of the several species, in order to discover whether their ocelli shewed any tendency to disappear; and to my great satisfaction, this appeared to be so. The central tail-feathers of P. napoleonis have the two ocelli on each side of the shaft perfectly developed; but the inner ocellus becomes less and less conspicuous on the more exterior tail-feathers, until a mere shadow or rudiment is left on the inner side of the outermost feather. Again, in P. malaccense, the ocelli on the tail-coverts are, as we have seen, confluent; and these feathers are of unusual length, being two-thirds of the length of the tail-feathers, so that in both these respects they approach the tail-coverts of the peacock. Now in P. malaccense, the two central tail-feathers alone are ornamented, each with two brightly-coloured ocelli, the inner ocellus having completely disappeared from all the other tail-feathers. Consequently the tail-coverts and tail-feathers of this species of Polyplectron make a near approach in structure and ornamentation to the corresponding feathers of the peacock. As far, then, as gradation throws light on the steps by which the magnificent train of the peacock has been acquired, hardly anything more is needed. If we picture to ourselves a progenitor of the peacock in an almost exactly intermediate condition between the existing peacock, with his enormously elongated tail-coverts, ornamented with single ocelli, and an ordinary gallinaceous bird with short tail-coverts, merely spotted with some colour, we shall see a bird allied to Polyplectron--that is, with tail-coverts, capable of erection and expansion, ornamented with two partially confluent ocelli, and long enough almost to conceal the tail-feathers, the latter having already partially lost their ocelli. The indentation of the central disc and of the surrounding zones of the ocellus, in both species of peacock, speaks plainly in favour of this view, and is otherwise inexplicable. The males of Polyplectron are no doubt beautiful birds, but their beauty, when viewed from a little distance, cannot be compared with that of the peacock. Many female progenitors of the peacock must, during a long line of descent, have appreciated this superiority; for they have unconsciously, by the continued preference for the most beautiful males, rendered the peacock the most splendid of living birds. ARGUS PHEASANT. Another excellent case for investigation is offered by the ocelli on the wing-feathers of the Argus pheasant, which are shaded in so wonderful a manner as to resemble balls lying loose within sockets, and consequently differ from ordinary ocelli. No one, I presume, will attribute the shading, which has excited the admiration of many experienced artists, to chance--to the fortuitous concourse of atoms of colouring matter. That these ornaments should have been formed through the selection of many successive variations, not one of which was originally intended to produce the ball-and-socket effect, seems as incredible as that one of Raphael's Madonnas should have been formed by the selection of chance daubs of paint made by a long succession of young artists, not one of whom intended at first to draw the human figure. In order to discover how the ocelli have been developed, we cannot look to a long line of progenitors, nor to many closely-allied forms, for such do not now exist. But fortunately the several feathers on the wing suffice to give us a clue to the problem, and they prove to demonstration that a gradation is at least possible from a mere spot to a finished ball-and-socket ocellus. [Fig. 57. Part of secondary wing-feather of Argus pheasant, shewing two perfect ocelli, a and b. A, B, C, D, etc., are dark stripes running obliquely down, each to an ocellus. [Much of the web on both sides, especially to the left of the shaft, has been cut off.] Fig.59. Portion of one of the secondary wing-feathers near to the body, shewing the so-called elliptic ornaments. The right-hand figure is given merely as a diagram for the sake of the letters of reference. A, B, C, D, etc. Rows of spots running down to and forming the elliptic ornaments. b. Lowest spot or mark in row B. c. The next succeeding spot or mark in the same row. d. Apparently a broken prolongation of the spot c. in the same row B.] The wing-feathers, bearing the ocelli, are covered with dark stripes (Fig. 57) or with rows of dark spots (Fig. 59), each stripe or row of spots running obliquely down the outer side of the shaft to one of the ocelli. The spots are generally elongated in a line transverse to the row in which they stand. They often become confluent either in the line of the row--and then they form a longitudinal stripe--or transversely, that is, with the spots in the adjoining rows, and then they form transverse stripes. A spot sometimes breaks up into smaller spots, which still stand in their proper places. It will be convenient first to describe a perfect ball-and-socket ocellus. This consists of an intensely black circular ring, surrounding a space shaded so as exactly to resemble a ball. The figure here given has been admirably drawn by Mr. Ford and well engraved, but a woodcut cannot exhibit the exquisite shading of the original. The ring is almost always slightly broken or interrupted (Fig. 57) at a point in the upper half, a little to the right of and above the white shade on the enclosed ball; it is also sometimes broken towards the base on the right hand. These little breaks have an important meaning. The ring is always much thickened, with the edges ill-defined towards the left-hand upper corner, the feather being held erect, in the position in which it is here drawn. Beneath this thickened part there is on the surface of the ball an oblique almost pure-white mark, which shades off downwards into a pale-leaden hue, and this into yellowish and brown tints, which insensibly become darker and darker towards the lower part of the ball. It is this shading which gives so admirably the effect of light shining on a convex surface. If one of the balls be examined, it will be seen that the lower part is of a brown tint and is indistinctly separated by a curved oblique line from the upper part, which is yellower and more leaden; this curved oblique line runs at right angles to the longer axis of the white patch of light, and indeed of all the shading; but this difference in colour, which cannot of course be shewn in the woodcut, does not in the least interfere with the perfect shading of the ball. It should be particularly observed that each ocellus stands in obvious connection either with a dark stripe, or with a longitudinal row of dark spots, for both occur indifferently on the same feather. Thus in Fig. 57 stripe A runs to ocellus a; B runs to ocellus b; stripe C is broken in the upper part, and runs down to the next succeeding ocellus, not represented in the woodcut; D to the next lower one, and so with the stripes E and F. Lastly, the several ocelli are separated from each other by a pale surface bearing irregular black marks. [Fig. 58. Basal part of the secondary wing feather, nearest to the body.] I will next describe the other extreme of the series, namely, the first trace of an ocellus. The short secondary wing-feather (Fig. 58), nearest to the body, is marked like the other feathers, with oblique, longitudinal, rather irregular, rows of very dark spots. The basal spot, or that nearest the shaft, in the five lower rows (excluding the lowest one) is a little larger than the other spots of the same row, and a little more elongated in a transverse direction. It differs also from the other spots by being bordered on its upper side with some dull fulvous shading. But this spot is not in any way more remarkable than those on the plumage of many birds, and might easily be overlooked. The next higher spot does not differ at all from the upper ones in the same row. The larger basal spots occupy exactly the same relative position on these feathers as do the perfect ocelli on the longer wing-feathers. By looking to the next two or three succeeding wing-feathers, an absolutely insensible gradation can be traced from one of the last-described basal spots, together with the next higher one in the same row, to a curious ornament, which cannot be called an ocellus, and which I will name, from the want of a better term, an "elliptic ornament." These are shewn in the accompanying figure (Fig. 59). We here see several oblique rows, A, B, C, D, etc. (see the lettered diagram on the right hand), of dark spots of the usual character. Each row of spots runs down to and is connected with one of the elliptic ornaments, in exactly the same manner as each stripe in Fig. 57 runs down to and is connected with one of the ball-and-socket ocelli. Looking to any one row, for instance, B, in Fig. 59, the lowest mark (b) is thicker and considerably longer than the upper spots, and has its left extremity pointed and curved upwards. This black mark is abruptly bordered on its upper side by a rather broad space of richly shaded tints, beginning with a narrow brown zone, which passes into orange, and this into a pale leaden tint, with the end towards the shaft much paler. These shaded tints together fill up the whole inner space of the elliptic ornament. The mark (b) corresponds in every respect with the basal shaded spot of the simple feather described in the last paragraph (Fig. 58), but is more highly developed and more brightly coloured. Above and to the right of this spot (b, Fig. 59), with its bright shading, there is a long narrow, black mark (c), belonging to the same row, and which is arched a little downwards so as to face (b). This mark is sometimes broken into two portions. It is also narrowly edged on the lower side with a fulvous tint. To the left of and above c, in the same oblique direction, but always more or less distinct from it, there is another black mark (d). This mark is generally sub-triangular and irregular in shape, but in the one lettered in the diagram it is unusually narrow, elongated, and regular. It apparently consists of a lateral and broken prolongation of the mark (c), together with its confluence with a broken and prolonged part of the next spot above; but I do not feel sure of this. These three marks, b, c, and d, with the intervening bright shades, form together the so-called elliptic ornament. These ornaments placed parallel to the shaft, manifestly correspond in position with the ball-and-socket ocelli. Their extremely elegant appearance cannot be appreciated in the drawing, as the orange and leaden tints, contrasting so well with the black marks, cannot be shewn. [Fig. 60. An ocellus in an intermediate condition between the elliptic ornament and the perfect ball-and-socket ocellus.] Between one of the elliptic ornaments and a perfect ball-and-socket ocellus, the gradation is so perfect that it is scarcely possible to decide when the latter term ought to be used. The passage from the one into the other is effected by the elongation and greater curvature in opposite directions of the lower black mark (b, Fig. 59), and more especially of the upper one (c), together with the contraction of the elongated sub-triangular or narrow mark (d), so that at last these three marks become confluent, forming an irregular elliptic ring. This ring is gradually rendered more and more circular and regular, increasing at the same time in diameter. I have here given a drawing (Fig. 60) of the natural size of an ocellus not as yet quite perfect. The lower part of the black ring is much more curved than is the lower mark in the elliptic ornament (b, Fig. 59). The upper part of the ring consists of two or three separate portions; and there is only a trace of the thickening of the portion which forms the black mark above the white shade. This white shade itself is not as yet much concentrated; and beneath it the surface is brighter coloured than in a perfect ball-and-socket ocellus. Even in the most perfect ocelli traces of the junction of three or four elongated black marks, by which the ring has been formed, may often be detected. The irregular sub-triangular or narrow mark (d, Fig. 59), manifestly forms, by its contraction and equalisation, the thickened portion of the ring above the white shade on a perfect ball-and-socket ocellus. The lower part of the ring is invariably a little thicker than the other parts (Fig. 57), and this follows from the lower black mark of the elliptic ornament (b, Fig. 59) having originally been thicker than the upper mark (c). Every step can be followed in the process of confluence and modification; and the black ring which surrounds the ball of the ocellus is unquestionably formed by the union and modification of the three black marks, b, c, d, of the elliptic ornament. The irregular zigzag black marks between the successive ocelli (Fig. 57) are plainly due to the breaking up of the somewhat more regular but similar marks between the elliptic ornaments. The successive steps in the shading of the ball-and-socket ocelli can be followed out with equal clearness. The brown, orange, and pale-leadened narrow zones, which border the lower black mark of the elliptic ornament, can be seen gradually to become more and more softened and shaded into each other, with the upper lighter part towards the left-hand corner rendered still lighter, so as to become almost white, and at the same time more contracted. But even in the most perfect ball-and-socket ocelli a slight difference in the tints, though not in the shading, between the upper and lower parts of the ball can be perceived, as before noticed; and the line of separation is oblique, in the same direction as the bright coloured shades of the elliptic ornaments. Thus almost every minute detail in the shape and colouring of the ball-and-socket ocelli can be shewn to follow from gradual changes in the elliptic ornaments; and the development of the latter can be traced by equally small steps from the union of two almost simple spots, the lower one (Fig. 58) having some dull fulvous shading on its upper side. [Fig. 61. Portion near summit of one of the secondary wing-feathers, bearing perfect ball-and-socket ocelli. a. Ornamented upper part. b. Uppermost, imperfect ball-and-socket ocellus. (The shading above the white mark on the summit of the ocellus is here a little too dark.) c. Perfect ocellus.] The extremities of the longer secondary feathers which bear the perfect ball-and-socket ocelli, are peculiarly ornamented (Fig. 61). The oblique longitudinal stripes suddenly cease upwards and become confused; and above this limit the whole upper end of the feather (a) is covered with white dots, surrounded by little black rings, standing on a dark ground. The oblique stripe belonging to the uppermost ocellus (b) is barely represented by a very short irregular black mark with the usual, curved, transverse base. As this stripe is thus abruptly cut off, we can perhaps understand from what has gone before, how it is that the upper thickened part of the ring is here absent; for, as before stated, this thickened part apparently stands in some relation with a broken prolongation from the next higher spot. From the absence of the upper and thickened part of the ring, the uppermost ocellus, though perfect in all other respects, appears as if its top had been obliquely sliced off. It would, I think, perplex any one, who believes that the plumage of the Argus pheasant was created as we now see it, to account for the imperfect condition of the uppermost ocellus. I should add that on the secondary wing-feather farthest from the body all the ocelli are smaller and less perfect than on the other feathers, and have the upper part of the ring deficient, as in the case just mentioned. The imperfection here seems to be connected with the fact that the spots on this feather shew less tendency than usual to become confluent into stripes; they are, on the contrary, often broken up into smaller spots, so that two or three rows run down to the same ocellus. There still remains another very curious point, first observed by Mr. T.W. Wood (51. The 'Field,' May 28, 1870.), which deserves attention. In a photograph, given me by Mr. Ward, of a specimen mounted as in the act of display, it may be seen that on the feathers which are held perpendicularly, the white marks on the ocelli, representing light reflected from a convex surface, are at the upper or further end, that is, are directed upwards; and the bird whilst displaying himself on the ground would naturally be illuminated from above. But here comes the curious point; the outer feathers are held almost horizontally, and their ocelli ought likewise to appear as if illuminated from above, and consequently the white marks ought to be placed on the upper sides of the ocelli; and, wonderful as is the fact, they are thus placed! Hence the ocelli on the several feathers, though occupying very different positions with respect to the light, all appear as if illuminated from above, just as an artist would have shaded them. Nevertheless they are not illuminated from strictly the same point as they ought to be; for the white marks on the ocelli of the feathers which are held almost horizontally, are placed rather too much towards the further end; that is, they are not sufficiently lateral. We have, however, no right to expect absolute perfection in a part rendered ornamental through sexual selection, any more than we have in a part modified through natural selection for real use; for instance, in that wondrous organ the human eye. And we know what Helmholtz, the highest authority in Europe on the subject, has said about the human eye; that if an optician had sold him an instrument so carelessly made, he would have thought himself fully justified in returning it. (52. 'Popular Lectures on Scientific Subjects,' Eng. trans. 1873, pp. 219, 227, 269, 390.) We have now seen that a perfect series can be followed, from simple spots to the wonderful ball-and-socket ornaments. Mr. Gould, who kindly gave me some of these feathers, fully agrees with me in the completeness of the gradation. It is obvious that the stages in development exhibited by the feathers on the same bird do not at all necessarily shew us the steps passed through by the extinct progenitors of the species; but they probably give us the clue to the actual steps, and they at least prove to demonstration that a gradation is possible. Bearing in mind how carefully the male Argus pheasant displays his plumes before the female, as well as the many facts rendering it probable that female birds prefer the more attractive males, no one who admits the agency of sexual selection in any case will deny that a simple dark spot with some fulvous shading might be converted, through the approximation and modification of two adjoining spots, together with some slight increase of colour, into one of the so-called elliptic ornaments. These latter ornaments have been shewn to many persons, and all have admitted that they are beautiful, some thinking them even more so than the ball-and-socket ocelli. As the secondary plumes became lengthened through sexual selection, and as the elliptic ornaments increased in diameter, their colours apparently became less bright; and then the ornamentation of the plumes had to be gained by an improvement in the pattern and shading; and this process was carried on until the wonderful ball-and-socket ocelli were finally developed. Thus we can understand--and in no other way as it seems to me--the present condition and origin of the ornaments on the wing-feathers of the Argus pheasant. From the light afforded by the principle of gradation--from what we know of the laws of variation--from the changes which have taken place in many of our domesticated birds--and, lastly, from the character (as we shall hereafter see more clearly) of the immature plumage of young birds--we can sometimes indicate, with a certain amount of confidence, the probable steps by which the males have acquired their brilliant plumage and various ornaments; yet in many cases we are involved in complete darkness. Mr. Gould several years ago pointed out to me a humming-bird, the Urosticte benjamini, remarkable for the curious differences between the sexes. The male, besides a splendid gorget, has greenish-black tail-feathers, with the four CENTRAL ones tipped with white; in the female, as with most of the allied species, the three OUTER tail-feathers on each side are tipped with white, so that the male has the four central, whilst the female has the six exterior feathers ornamented with white tips. What makes the case more curious is that, although the colouring of the tail differs remarkably in both sexes of many kinds of humming-birds, Mr. Gould does not know a single species, besides the Urosticte, in which the male has the four central feathers tipped with white. The Duke of Argyll, in commenting on this case (53. 'The Reign of Law,' 1867, p. 247.), passes over sexual selection, and asks, "What explanation does the law of natural selection give of such specific varieties as these?" He answers "none whatever"; and I quite agree with him. But can this be so confidently said of sexual selection? Seeing in how many ways the tail-feathers of humming-birds differ, why should not the four central feathers have varied in this one species alone, so as to have acquired white tips? The variations may have been gradual, or somewhat abrupt as in the case recently given of the humming-birds near Bogota, in which certain individuals alone have the "central tail-feathers tipped with beautiful green." In the female of the Urosticte I noticed extremely minute or rudimental white tips to the two outer of the four central black tail-feathers; so that here we have an indication of change of some kind in the plumage of this species. If we grant the possibility of the central tail-feathers of the male varying in whiteness, there is nothing strange in such variations having been sexually selected. The white tips, together with the small white ear-tufts, certainly add, as the Duke of Argyll admits, to the beauty of the male; and whiteness is apparently appreciated by other birds, as may be inferred from such cases as the snow-white male of the Bell-bird. The statement made by Sir R. Heron should not be forgotten, namely, that his peahens, when debarred from access to the pied peacock, would not unite with any other male, and during that season produced no offspring. Nor is it strange that variations in the tail-feathers of the Urosticte should have been specially selected for the sake of ornament, for the next succeeding genus in the family takes its name of Metallura from the splendour of these feathers. We have, moreover, good evidence that humming-birds take especial pains in displaying their tail-feathers; Mr. Belt (54. 'The Naturalist in Nicaragua,' 1874, p. 112.), after describing the beauty of the Florisuga mellivora, says, "I have seen the female sitting on a branch, and two males displaying their charms in front of her. One would shoot up like a rocket, then suddenly expanding the snow-white tail, like an inverted parachute, slowly descend in front of her, turning round gradually to shew off back and front...The expanded white tail covered more space than all the rest of the bird, and was evidently the grand feature in the performance. Whilst one male was descending, the other would shoot up and come slowly down expanded. The entertainment would end in a fight between the two performers; but whether the most beautiful or the most pugnacious was the accepted suitor, I know not." Mr. Gould, after describing the peculiar plumage of the Urosticte, adds, "that ornament and variety is the sole object, I have myself but little doubt." (55. 'Introduction to the Trochilidae,' 1861, p. 110.) If this be admitted, we can perceive that the males which during former times were decked in the most elegant and novel manner would have gained an advantage, not in the ordinary struggle for life, but in rivalry with other males, and would have left a larger number of offspring to inherit their newly-acquired beauty. CHAPTER XV. Birds--continued. Discussion as to why the males alone of some species, and both sexes of others, are brightly coloured--On sexually-limited inheritance, as applied to various structures and to brightly-coloured plumage--Nidification in relation to colour--Loss of nuptial plumage during the winter. We have in this chapter to consider why the females of many birds have not acquired the same ornaments as the male; and why, on the other hand, both sexes of many other birds are equally, or almost equally, ornamented? In the following chapter we shall consider the few cases in which the female is more conspicuously coloured than the male. In my 'Origin of Species' (1. Fourth edition, 1866, p. 241.) I briefly suggested that the long tail of the peacock would be inconvenient and the conspicuous black colour of the male capercailzie dangerous, to the female during the period of incubation: and consequently that the transmission of these characters from the male to the female offspring had been checked through natural selection. I still think that this may have occurred in some few instances: but after mature reflection on all the facts which I have been able to collect, I am now inclined to believe that when the sexes differ, the successive variations have generally been from the first limited in their transmission to the same sex in which they first arose. Since my remarks appeared, the subject of sexual coloration has been discussed in some very interesting papers by Mr. Wallace (2. 'Westminster Review,' July 1867. 'Journal of Travel,' vol. i. 1868, p. 73.), who believes that in almost all cases the successive variations tended at first to be transmitted equally to both sexes; but that the female was saved, through natural selection, from acquiring the conspicuous colours of the male, owing to the danger which she would thus have incurred during incubation. This view necessitates a tedious discussion on a difficult point, namely, whether the transmission of a character, which is at first inherited by both sexes can be subsequently limited in its transmission to one sex alone by means of natural selection. We must bear in mind, as shewn in the preliminary chapter on sexual selection, that characters which are limited in their development to one sex are always latent in the other. An imaginary illustration will best aid us in seeing the difficulty of the case; we may suppose that a fancier wished to make a breed of pigeons, in which the males alone should be coloured of a pale blue, whilst the females retained their former slaty tint. As with pigeons characters of all kinds are usually transmitted to both sexes equally, the fancier would have to try to convert this latter form of inheritance into sexually-limited transmission. All that he could do would be to persevere in selecting every male pigeon which was in the least degree of a paler blue; and the natural result of this process, if steadily carried on for a long time, and if the pale variations were strongly inherited or often recurred, would be to make his whole stock of a lighter blue. But our fancier would be compelled to match, generation after generation, his pale blue males with slaty females, for he wishes to keep the latter of this colour. The result would generally be the production either of a mongrel piebald lot, or more probably the speedy and complete loss of the pale-blue tint; for the primordial slaty colour would be transmitted with prepotent force. Supposing, however, that some pale-blue males and slaty females were produced during each successive generation, and were always crossed together, then the slaty females would have, if I may use the expression, much blue blood in their veins, for their fathers, grandfathers, etc., will all have been blue birds. Under these circumstances it is conceivable (though I know of no distinct facts rendering it probable) that the slaty females might acquire so strong a latent tendency to pale-blueness, that they would not destroy this colour in their male offspring, their female offspring still inheriting the slaty tint. If so, the desired end of making a breed with the two sexes permanently different in colour might be gained. The extreme importance, or rather necessity in the above case of the desired character, namely, pale-blueness, being present though in a latent state in the female, so that the male offspring should not be deteriorated, will be best appreciated as follows: the male of Soemmerring's pheasant has a tail thirty-seven inches in length, whilst that of the female is only eight inches; the tail of the male common pheasant is about twenty inches, and that of the female twelve inches long. Now if the female Soemmerring pheasant with her SHORT tail were crossed with the male common pheasant, there can be no doubt that the male hybrid offspring would have a much LONGER tail than that of the pure offspring of the common pheasant. On the other hand, if the female common pheasant, with a tail much longer than that of the female Soemmerring pheasant, were crossed with the male of the latter, the male hybrid offspring would have a much SHORTER tail than that of the pure offspring of Soemmerring's pheasant. (3. Temminck says that the tail of the female Phasianus Soemmerringii is only six inches long, 'Planches coloriees,' vol. v. 1838, pp. 487 and 488: the measurements above given were made for me by Mr. Sclater. For the common pheasant, see Macgillivray, 'History of British Birds,' vol. i. pp. 118-121.) Our fancier, in order to make his new breed with the males of a pale-blue tint, and the females unchanged, would have to continue selecting the males during many generations; and each stage of paleness would have to be fixed in the males, and rendered latent in the females. The task would be an extremely difficult one, and has never been tried, but might possibly be successfully carried out. The chief obstacle would be the early and complete loss of the pale-blue tint, from the necessity of reiterated crosses with the slaty female, the latter not having at first any LATENT tendency to produce pale-blue offspring. On the other hand, if one or two males were to vary ever so slightly in paleness, and the variations were from the first limited in their transmission to the male sex, the task of making a new breed of the desired kind would be easy, for such males would simply have to be selected and matched with ordinary females. An analogous case has actually occurred, for there are breeds of the pigeon in Belgium (4. Dr. Chapuis, 'Le Pigeon Voyageur Belge,' 1865, p. 87.) in which the males alone are marked with black striae. So again Mr. Tegetmeier has recently shewn (5. The 'Field,' Sept. 1872.) that dragons not rarely produce silver-coloured birds, which are almost always hens; and he himself has bred ten such females. It is on the other hand a very unusual event when a silver male is produced; so that nothing would be easier, if desired, than to make a breed of dragons with blue males and silver females. This tendency is indeed so strong that when Mr. Tegetmeier at last got a silver male and matched him with one of the silver females, he expected to get a breed with both sexes thus coloured; he was however disappointed, for the young male reverted to the blue colour of his grandfather, the young female alone being silver. No doubt with patience this tendency to reversion in the males, reared from an occasional silver male matched with a silver hen, might be eliminated, and then both sexes would be coloured alike; and this very process has been followed with success by Mr. Esquilant in the case of silver turbits. With fowls, variations of colour, limited in their transmission to the male sex, habitually occur. When this form of inheritance prevails, it might well happen that some of the successive variations would be transferred to the female, who would then slightly resemble the male, as actually occurs in some breeds. Or again, the greater number, but not all, of the successive steps might be transferred to both sexes, and the female would then closely resemble the male. There can hardly be a doubt that this is the cause of the male pouter pigeon having a somewhat larger crop, and of the male carrier pigeon having somewhat larger wattles, than their respective females; for fanciers have not selected one sex more than the other, and have had no wish that these characters should be more strongly displayed in the male than in the female, yet this is the case with both breeds. The same process would have to be followed, and the same difficulties encountered, if it were desired to make a breed with the females alone of some new colour. Lastly, our fancier might wish to make a breed with the two sexes differing from each other, and both from the parent species. Here the difficulty would be extreme, unless the successive variations were from the first sexually limited on both sides, and then there would be no difficulty. We see this with the fowl; thus the two sexes of the pencilled Hamburghs differ greatly from each other, and from the two sexes of the aboriginal Gallus bankiva; and both are now kept constant to their standard of excellence by continued selection, which would be impossible unless the distinctive characters of both were limited in their transmission. The Spanish fowl offers a more curious case; the male has an immense comb, but some of the successive variations, by the accumulation of which it was acquired, appear to have been transferred to the female; for she has a comb many times larger than that of the females of the parent species. But the comb of the female differs in one respect from that of the male, for it is apt to lop over; and within a recent period it has been ordered by the fancy that this should always be the case, and success has quickly followed the order. Now the lopping of the comb must be sexually limited in its transmission, otherwise it would prevent the comb of the male from being perfectly upright, which would be abhorrent to every fancier. On the other hand, the uprightness of the comb in the male must likewise be a sexually-limited character, otherwise it would prevent the comb of the female from lopping over. From the foregoing illustrations, we see that even with almost unlimited time at command, it would be an extremely difficult and complex, perhaps an impossible process, to change one form of transmission into the other through selection. Therefore, without distinct evidence in each case, I am unwilling to admit that this has been effected in natural species. On the other hand, by means of successive variations, which were from the first sexually limited in their transmission, there would not be the least difficulty in rendering a male bird widely different in colour or in any other character from the female; the latter being left unaltered, or slightly altered, or specially modified for the sake of protection. As bright colours are of service to the males in their rivalry with other males, such colours would be selected whether or not they were transmitted exclusively to the same sex. Consequently the females might be expected often to partake of the brightness of the males to a greater or less degree; and this occurs with a host of species. If all the successive variations were transmitted equally to both sexes, the females would be indistinguishable from the males; and this likewise occurs with many birds. If, however, dull colours were of high importance for the safety of the female during incubation, as with many ground birds, the females which varied in brightness, or which received through inheritance from the males any marked accession of brightness, would sooner or later be destroyed. But the tendency in the males to continue for an indefinite period transmitting to their female offspring their own brightness, would have to be eliminated by a change in the form of inheritance; and this, as shewn by our previous illustration, would be extremely difficult. The more probable result of the long-continued destruction of the more brightly-coloured females, supposing the equal form of transmission to prevail, would be the lessening or annihilation of the bright colours of the males, owing to their continual crossing with the duller females. It would be tedious to follow out all the other possible results; but I may remind the reader that if sexually-limited variations in brightness occurred in the females, even if they were not in the least injurious to them and consequently were not eliminated, yet they would not be favoured or selected, for the male usually accepts any female, and does not select the more attractive individuals; consequently these variations would be liable to be lost, and would have little influence on the character of the race; and this will aid in accounting for the females being commonly duller-coloured than the males. In the eighth chapter instances were given, to which many might here be added, of variations occurring at various ages, and inherited at the corresponding age. It was also shewn that variations which occur late in life are commonly transmitted to the same sex in which they first appear; whilst variations occurring early in life are apt to be transmitted to both sexes; not that all the cases of sexually-limited transmission can thus be accounted for. It was further shewn that if a male bird varied by becoming brighter whilst young, such variations would be of no service until the age for reproduction had arrived, and there was competition between rival males. But in the case of birds living on the ground and commonly in need of the protection of dull colours, bright tints would be far more dangerous to the young and inexperienced than to the adult males. Consequently the males which varied in brightness whilst young would suffer much destruction and be eliminated through natural selection; on the other hand, the males which varied in this manner when nearly mature, notwithstanding that they were exposed to some additional danger, might survive, and from being favoured through sexual selection, would procreate their kind. As a relation often exists between the period of variation and the form of transmission, if the bright-coloured young males were destroyed and the mature ones were successful in their courtship, the males alone would acquire brilliant colours and would transmit them exclusively to their male offspring. But I by no means wish to maintain that the influence of age on the form of transmission, is the sole cause of the great difference in brilliancy between the sexes of many birds. When the sexes of birds differ in colour, it is interesting to determine whether the males alone have been modified by sexual selection, the females having been left unchanged, or only partially and indirectly thus changed; or whether the females have been specially modified through natural selection for the sake of protection. I will therefore discuss this question at some length, even more fully than its intrinsic importance deserves; for various curious collateral points may thus be conveniently considered. Before we enter on the subject of colour, more especially in reference to Mr. Wallace's conclusions, it may be useful to discuss some other sexual differences under a similar point of view. A breed of fowls formerly existed in Germany (6. Bechstein, 'Naturgeschichte Deutschlands,' 1793, B. iii. 339.) in which the hens were furnished with spurs; they were good layers, but they so greatly disturbed their nests with their spurs that they could not be allowed to sit on their own eggs. Hence at one time it appeared to me probable that with the females of the wild Gallinaceae the development of spurs had been checked through natural selection, from the injury thus caused to their nests. This seemed all the more probable, as wing-spurs, which would not be injurious during incubation, are often as well-developed in the female as in the male; though in not a few cases they are rather larger in the male. When the male is furnished with leg-spurs the female almost always exhibits rudiments of them,--the rudiment sometimes consisting of a mere scale, as in Gallus. Hence it might be argued that the females had aboriginally been furnished with well-developed spurs, but that these had subsequently been lost through disuse or natural selection. But if this view be admitted, it would have to be extended to innumerable other cases; and it implies that the female progenitors of the existing spur-bearing species were once encumbered with an injurious appendage. In some few genera and species, as in Galloperdix, Acomus, and the Javan peacock (Pavo muticus), the females, as well as the males, possess well-developed leg-spurs. Are we to infer from this fact that they construct a different sort of nest from that made by their nearest allies, and not liable to be injured by their spurs; so that the spurs have not been removed? Or are we to suppose that the females of these several species especially require spurs for their defence? It is a more probable conclusion that both the presence and absence of spurs in the females result from different laws of inheritance having prevailed, independently of natural selection. With the many females in which spurs appear as rudiments, we may conclude that some few of the successive variations, through which they were developed in the males, occurred very early in life, and were consequently transferred to the females. In the other and much rarer cases, in which the females possess fully developed spurs, we may conclude that all the successive variations were transferred to them; and that they gradually acquired and inherited the habit of not disturbing their nests. The vocal organs and the feathers variously modified for producing sound, as well as the proper instincts for using them, often differ in the two sexes, but are sometimes the same in both. Can such differences be accounted for by the males having acquired these organs and instincts, whilst the females have been saved from inheriting them, on account of the danger to which they would have been exposed by attracting the attention of birds or beasts of prey? This does not seem to me probable, when we think of the multitude of birds which with impunity gladden the country with their voices during the spring. (7. Daines Barrington, however, thought it probable ('Philosophical Transactions,' 1773, p. 164) that few female birds sing, because the talent would have been dangerous to them during incubation. He adds, that a similar view may possibly account for the inferiority of the female to the male in plumage.) It is a safer conclusion that, as vocal and instrumental organs are of special service only to the males during their courtship, these organs were developed through sexual selection and their constant use in that sex alone--the successive variations and the effects of use having been from the first more or less limited in transmission to the male offspring. Many analogous cases could be adduced; those for instance of the plumes on the head being generally longer in the male than in the female, sometimes of equal length in both sexes, and occasionally absent in the female,--these several cases occurring in the same group of birds. It would be difficult to account for such a difference between the sexes by the female having been benefited by possessing a slightly shorter crest than the male, and its consequent diminution or complete suppression through natural selection. But I will take a more favourable case, namely the length of the tail. The long train of the peacock would have been not only inconvenient but dangerous to the peahen during the period of incubation and whilst accompanying her young. Hence there is not the least a priori improbability in the development of her tail having been checked through natural selection. But the females of various pheasants, which apparently are exposed on their open nests to as much danger as the peahen, have tails of considerable length. The females as well as the males of the Menura superba have long tails, and they build a domed nest, which is a great anomaly in so large a bird. Naturalists have wondered how the female Menura could manage her tail during incubation; but it is now known (8. Mr. Ramsay, in 'Proc. Zoolog. Soc.' 1868, p. 50.) that she "enters the nest head first, and then turns round with her tail sometimes over her back, but more often bent round by her side. Thus in time the tail becomes quite askew, and is a tolerable guide to the length of time the bird has been sitting." Both sexes of an Australian kingfisher (Tanysiptera sylvia) have the middle tail-feathers greatly lengthened, and the female makes her nest in a hole; and as I am informed by Mr. R.B. Sharpe these feathers become much crumpled during incubation. In these two latter cases the great length of the tail-feathers must be in some degree inconvenient to the female; and as in both species the tail-feathers of the female are somewhat shorter than those of the male, it might be argued that their full development had been prevented through natural selection. But if the development of the tail of the peahen had been checked only when it became inconveniently or dangerously great, she would have retained a much longer tail than she actually possesses; for her tail is not nearly so long, relatively to the size of her body, as that of many female pheasants, nor longer than that of the female turkey. It must also be borne in mind that, in accordance with this view, as soon as the tail of the peahen became dangerously long, and its development was consequently checked, she would have continually reacted on her male progeny, and thus have prevented the peacock from acquiring his present magnificent train. We may therefore infer that the length of the tail in the peacock and its shortness in the peahen are the result of the requisite variations in the male having been from the first transmitted to the male offspring alone. We are led to a nearly similar conclusion with respect to the length of the tail in the various species of pheasants. In the Eared pheasant (Crossoptilon auritum) the tail is of equal length in both sexes, namely sixteen or seventeen inches; in the common pheasant it is about twenty inches long in the male and twelve in the female; in Soemmerring's pheasant, thirty-seven inches in the male and only eight in the female; and lastly in Reeve's pheasant it is sometimes actually seventy-two inches long in the male and sixteen in the female. Thus in the several species, the tail of the female differs much in length, irrespectively of that of the male; and this can be accounted for, as it seems to me, with much more probability, by the laws of inheritance,--that is by the successive variations having been from the first more or less closely limited in their transmission to the male sex than by the agency of natural selection, resulting from the length of tail being more or less injurious to the females of these several allied species. We may now consider Mr. Wallace's arguments in regard to the sexual coloration of birds. He believes that the bright tints originally acquired through sexual selection by the males would in all, or almost all cases, have been transmitted to the females, unless the transference had been checked through natural selection. I may here remind the reader that various facts opposed to this view have already been given under reptiles, amphibians, fishes and lepidoptera. Mr. Wallace rests his belief chiefly, but not exclusively, as we shall see in the next chapter, on the following statement (9. 'Journal of Travel,' edited by A. Murray, vol. i. 1868, p. 78.), that when both sexes are coloured in a very conspicuous manner, the nest is of such a nature as to conceal the sitting bird; but when there is a marked contrast of colour between the sexes, the male being gay and the female dull-coloured, the nest is open and exposes the sitting bird to view. This coincidence, as far as it goes, certainly seems to favour the belief that the females which sit on open nests have been specially modified for the sake of protection; but we shall presently see that there is another and more probable explanation, namely, that conspicuous females have acquired the instinct of building domed nests oftener than dull-coloured birds. Mr. Wallace admits that there are, as might have been expected, some exceptions to his two rules, but it is a question whether the exceptions are not so numerous as seriously to invalidate them. There is in the first place much truth in the Duke of Argyll's remark (10. 'Journal of Travel,' edited by A. Murray, vol. i. 1868, p. 281.) that a large domed nest is more conspicuous to an enemy, especially to all tree-haunting carnivorous animals, than a smaller open nest. Nor must we forget that with many birds which build open nests, the male sits on the eggs and aids the female in feeding the young: this is the case, for instance, with Pyranga aestiva (11. Audubon, 'Ornithological Biography,' vol. i. p. 233.), one of the most splendid birds in the United States, the male being vermilion, and the female light brownish-green. Now if brilliant colours had been extremely dangerous to birds whilst sitting on their open nests, the males in these cases would have suffered greatly. It might, however, be of such paramount importance to the male to be brilliantly coloured, in order to beat his rivals, that this may have more than compensated some additional danger. Mr. Wallace admits that with the King-crows (Dicrurus), Orioles, and Pittidae, the females are conspicuously coloured, yet build open nests; but he urges that the birds of the first group are highly pugnacious and could defend themselves; that those of the second group take extreme care in concealing their open nests, but this does not invariably hold good (12. Jerdon, 'Birds of India,' vol. ii. p. 108. Gould's 'Handbook of the Birds of Australia,' vol. i. p. 463.); and that with the birds of the third group the females are brightly coloured chiefly on the under surface. Besides these cases, pigeons which are sometimes brightly, and almost always conspicuously coloured, and which are notoriously liable to the attacks of birds of prey, offer a serious exception to the rule, for they almost always build open and exposed nests. In another large family, that of the humming-birds, all the species build open nests, yet with some of the most gorgeous species the sexes are alike; and in the majority, the females, though less brilliant than the males, are brightly coloured. Nor can it be maintained that all female humming-birds, which are brightly coloured, escape detection by their tints being green, for some display on their upper surfaces red, blue, and other colours. (13. For instance, the female Eupetomena macroura has the head and tail dark blue with reddish loins; the female Lampornis porphyrurus is blackish-green on the upper surface, with the lores and sides of the throat crimson; the female Eulampis jugularis has the top of the head and back green, but the loins and the tail are crimson. Many other instances of highly conspicuous females could be given. See Mr. Gould's magnificent work on this family.) In regard to birds which build in holes or construct domed nests, other advantages, as Mr. Wallace remarks, besides concealment are gained, such as shelter from the rain, greater warmth, and in hot countries protection from the sun (14. Mr. Salvin noticed in Guatemala ('Ibis,' 1864, p. 375) that humming-birds were much more unwilling to leave their nests during very hot weather, when the sun was shining brightly, as if their eggs would be thus injured, than during cool, cloudy, or rainy weather.); so that it is no valid objection to his view that many birds having both sexes obscurely coloured build concealed nests. (15. I may specify, as instances of dull-coloured birds building concealed nests, the species belonging to eight Australian genera described in Gould's 'Handbook of the Birds of Australia,' vol. i. pp. 340, 362, 365, 383, 387, 389, 391, 414.) The female Horn-bill (Buceros), for instance, of India and Africa is protected during incubation with extraordinary care, for she plasters up with her own excrement the orifice of the hole in which she sits on her eggs, leaving only a small orifice through which the male feeds her; she is thus kept a close prisoner during the whole period of incubation (16. Mr. C. Horne, 'Proc. Zoolog. Soc.' 1869. p. 243.); yet female horn-bills are not more conspicuously coloured than many other birds of equal size which build open nests. It is a more serious objection to Mr. Wallace's view, as is admitted by him, that in some few groups the males are brilliantly coloured and the females obscure, and yet the latter hatch their eggs in domed nests. This is the case with the Grallinae of Australia, the Superb Warblers (Maluridae) of the same country, the Sun-birds (Nectariniae), and with several of the Australian Honey-suckers or Meliphagidae. (17. On the nidification and colours of these latter species, see Gould's 'Handbook to the Birds of Australia,' vol. i. pp. 504, 527.) If we look to the birds of England we shall see that there is no close and general relation between the colours of the female and the nature of the nest which is constructed. About forty of our British birds (excluding those of large size which could defend themselves) build in holes in banks, rocks, or trees, or construct domed nests. If we take the colours of the female goldfinch, bullfinch, or blackbird, as a standard of the degree of conspicuousness, which is not highly dangerous to the sitting female, then out of the above forty birds the females of only twelve can be considered as conspicuous to a dangerous degree, the remaining twenty-eight being inconspicuous. (18. I have consulted, on this subject, Macgillivray's 'British Birds,' and though doubts may be entertained in some cases in regard to the degree of concealment of the nest, and to the degree of conspicuousness of the female, yet the following birds, which all lay their eggs in holes or in domed nests, can hardly be considered, by the above standard, as conspicuous: Passer, 2 species; Sturnus, of which the female is considerably less brilliant than the male; Cinclus; Motallica boarula (?); Erithacus (?); Fruticola, 2 sp.; Saxicola; Ruticilla, 2 sp.; Sylvia, 3 sp.; Parus, 3 sp.; Mecistura; Anorthura; Certhia; Sitta; Yunx; Muscicapa, 2 sp.; Hirundo, 3 sp.; and Cypselus. The females of the following 12 birds may be considered as conspicuous according to the same standard, viz., Pastor, Motacilla alba, Parus major and P. caeruleus, Upupa, Picus, 4 sp., Coracias, Alcedo, and Merops.) Nor is there any close relation within the same genus between a well-pronounced difference in colour between the sexes, and the nature of the nest constructed. Thus the male house sparrow (Passer domesticus) differs much from the female, the male tree-sparrow (P. montanus) hardly at all, and yet both build well-concealed nests. The two sexes of the common fly-catcher (Muscicapa grisola) can hardly be distinguished, whilst the sexes of the pied fly-catcher (M. luctuosa) differ considerably, and both species build in holes or conceal their nests. The female blackbird (Turdus merula) differs much, the female ring-ouzel (T. torquatus) differs less, and the female common thrush (T. musicus) hardly at all from their respective males; yet all build open nests. On the other hand, the not very distantly-allied water-ouzel (Cinclus aquaticus) builds a domed nest, and the sexes differ about as much as in the ring-ouzel. The black and red grouse (Tetrao tetrix and T. scoticus) build open nests in equally well-concealed spots, but in the one species the sexes differ greatly, and in the other very little. Notwithstanding the foregoing objections, I cannot doubt, after reading Mr. Wallace's excellent essay, that looking to the birds of the world, a large majority of the species in which the females are conspicuously coloured (and in this case the males with rare exceptions are equally conspicuous), build concealed nests for the sake of protection. Mr. Wallace enumerates (19. 'Journal of Travel,' edited by A. Murray, vol. i. p. 78.) a long series of groups in which this rule holds good; but it will suffice here to give, as instances, the more familiar groups of kingfishers, toucans, trogons, puff-birds (Capitonidae), plantain-eaters (Musophagae, woodpeckers, and parrots. Mr. Wallace believes that in these groups, as the males gradually acquired through sexual selection their brilliant colours, these were transferred to the females and were not eliminated by natural selection, owing to the protection which they already enjoyed from their manner of nidification. According to this view, their present manner of nesting was acquired before their present colours. But it seems to me much more probable that in most cases, as the females were gradually rendered more and more brilliant from partaking of the colours of the male, they were gradually led to change their instincts (supposing that they originally built open nests), and to seek protection by building domed or concealed nests. No one who studies, for instance, Audubon's account of the differences in the nests of the same species in the Northern and Southern United States (20. See many statements in the 'Ornithological Biography.' See also some curious observations on the nests of Italian birds by Eugenio Bettoni, in the 'Atti della Società Italiana,' vol. xi. 1869, p. 487.), will feel any great difficulty in admitting that birds, either by a change (in the strict sense of the word) of their habits, or through the natural selection of so-called spontaneous variations of instinct, might readily be led to modify their manner of nesting. This way of viewing the relation, as far as it holds good, between the bright colours of female birds and their manner of nesting, receives some support from certain cases occurring in the Sahara Desert. Here, as in most other deserts, various birds, and many other animals, have had their colours adapted in a wonderful manner to the tints of the surrounding surface. Nevertheless there are, as I am informed by the Rev. Mr. Tristram, some curious exceptions to the rule; thus the male of the Monticola cyanea is conspicuous from his bright blue colour, and the female almost equally conspicuous from her mottled brown and white plumage; both sexes of two species of Dromolaea are of a lustrous black; so that these three species are far from receiving protection from their colours, yet they are able to survive, for they have acquired the habit of taking refuge from danger in holes or crevices in the rocks. With respect to the above groups in which the females are conspicuously coloured and build concealed nests, it is not necessary to suppose that each separate species had its nidifying instinct specially modified; but only that the early progenitors of each group were gradually led to build domed or concealed nests, and afterwards transmitted this instinct, together with their bright colours, to their modified descendants. As far as it can be trusted, the conclusion is interesting, that sexual selection together with equal or nearly equal inheritance by both sexes, have indirectly determined the manner of nidification of whole groups of birds. According to Mr. Wallace, even in the groups in which the females, from being protected in domed nests during incubation, have not had their bright colours eliminated through natural selection, the males often differ in a slight, and occasionally in a considerable degree from the females. This is a significant fact, for such differences in colour must be accounted for by some of the variations in the males having been from the first limited in transmission to the same sex; as it can hardly be maintained that these differences, especially when very slight, serve as a protection to the female. Thus all the species in the splendid group of the Trogons build in holes; and Mr. Gould gives figures (21. See his Monograph of the Trogonidae, 1st edition.) of both sexes of twenty-five species, in all of which, with one partial exception, the sexes differ sometimes slightly, sometimes conspicuously, in colour,--the males being always finer than the females, though the latter are likewise beautiful. All the species of kingfishers build in holes, and with most of the species the sexes are equally brilliant, and thus far Mr. Wallace's rule holds good; but in some of the Australian species the colours of the females are rather less vivid than those of the male; and in one splendidly-coloured species, the sexes differ so much that they were at first thought to be specifically distinct. (22. Namely, Cyanalcyon, Gould's 'Handbook to the Birds of Australia,' vol. i. p. 133; see, also, pp. 130, 136.) Mr. R.B. Sharpe, who has especially studied this group, has shewn me some American species (Ceryle) in which the breast of the male is belted with black. Again, in Carcineutes, the difference between the sexes is conspicuous: in the male the upper surface is dull-blue banded with black, the lower surface being partly fawn-coloured, and there is much red about the head; in the female the upper surface is reddish-brown banded with black, and the lower surface white with black markings. It is an interesting fact, as shewing how the same peculiar style of sexual colouring often characterises allied forms, that in three species of Dacelo the male differs from the female only in the tail being dull-blue banded with black, whilst that of the female is brown with blackish bars; so that here the tail differs in colour in the two sexes in exactly the same manner as the whole upper surface in the two sexes of Carcineutes. With parrots, which likewise build in holes, we find analogous cases: in most of the species, both sexes are brilliantly coloured and indistinguishable, but in not a few species the males are coloured rather more vividly than the females, or even very differently from them. Thus, besides other strongly-marked differences, the whole under surface of the male King Lory (Aprosmictus scapulatus) is scarlet, whilst the throat and chest of the female is green tinged with red: in the Euphema splendida there is a similar difference, the face and wing coverts moreover of the female being of a paler blue than in the male. (23. Every gradation of difference between the sexes may be followed in the parrots of Australia. See Gould's 'Handbook,' etc., vol. ii. pp. 14-102.) In the family of the tits (Parinae), which build concealed nests, the female of our common blue tomtit (Parus caeruleus), is "much less brightly coloured" than the male: and in the magnificent Sultan yellow tit of India the difference is greater. (24. Macgillivray's 'British Birds,' vol. ii. p. 433. Jerdon, 'Birds of India,' vol. ii. p. 282.) Again, in the great group of the woodpeckers (25. All the following facts are taken from M. Malherbe's magnificent 'Monographie des Picidees,' 1861.), the sexes are generally nearly alike, but in the Megapicus validus all those parts of the head, neck, and breast, which are crimson in the male are pale brown in the female. As in several woodpeckers the head of the male is bright crimson, whilst that of the female is plain, it occurred to me that this colour might possibly make the female dangerously conspicuous, whenever she put her head out of the hole containing her nest, and consequently that this colour, in accordance with Mr. Wallace's belief, had been eliminated. This view is strengthened by what Malherbe states with respect to Indopicus carlotta; namely, that the young females, like the young males, have some crimson about their heads, but that this colour disappears in the adult female, whilst it is intensified in the adult male. Nevertheless the following considerations render this view extremely doubtful: the male takes a fair share in incubation (26. Audubon's 'Ornithological Biography,' vol. ii. p. 75; see also the 'Ibis,' vol. i. p. 268.), and would be thus almost equally exposed to danger; both sexes of many species have their heads of an equally bright crimson; in other species the difference between the sexes in the amount of scarlet is so slight that it can hardly make any appreciable difference in the danger incurred; and lastly, the colouring of the head in the two sexes often differs slightly in other ways. The cases, as yet given, of slight and graduated differences in colour between the males and females in the groups, in which as a general rule the sexes resemble each other, all relate to species which build domed or concealed nests. But similar gradations may likewise be observed in groups in which the sexes as a general rule resemble each other, but which build open nests. As I have before instanced the Australian parrots, so I may here instance, without giving any details, the Australian pigeons. (27. Gould's 'Handbook to the Birds of Australia,' vol. ii. pp. 109-149.) It deserves especial notice that in all these cases the slight differences in plumage between the sexes are of the same general nature as the occasionally greater differences. A good illustration of this fact has already been afforded by those kingfishers in which either the tail alone or the whole upper surface of the plumage differs in the same manner in the two sexes. Similar cases may be observed with parrots and pigeons. The differences in colour between the sexes of the same species are, also, of the same general nature as the differences in colour between the distinct species of the same group. For when in a group in which the sexes are usually alike, the male differs considerably from the female, he is not coloured in a quite new style. Hence we may infer that within the same group the special colours of both sexes when they are alike, and the colours of the male, when he differs slightly or even considerably from the female, have been in most cases determined by the same general cause; this being sexual selection. It is not probable, as has already been remarked, that differences in colour between the sexes, when very slight, can be of service to the female as a protection. Assuming, however, that they are of service, they might be thought to be cases of transition; but we have no reason to believe that many species at any one time are undergoing change. Therefore we can hardly admit that the numerous females which differ very slightly in colour from their males are now all commencing to become obscure for the sake of protection. Even if we consider somewhat more marked sexual differences, is it probable, for instance, that the head of the female chaffinch,--the crimson on the breast of the female bullfinch,--the green of the female greenfinch,--the crest of the female golden-crested wren, have all been rendered less bright by the slow process of selection for the sake of protection? I cannot think so; and still less with the slight differences between the sexes of those birds which build concealed nests. On the other hand, the differences in colour between the sexes, whether great or small, may to a large extent be explained on the principle of the successive variations, acquired by the males through sexual selection, having been from the first more or less limited in their transmission to the females. That the degree of limitation should differ in different species of the same group will not surprise any one who has studied the laws of inheritance, for they are so complex that they appear to us in our ignorance to be capricious in their action. (28. See remarks to this effect in 'Variation of Animals and Plants under Domestication,' vol. ii. chap. xii.) As far as I can discover there are few large groups of birds in which all the species have both sexes alike and brilliantly coloured, but I hear from Mr. Sclater, that this appears to be the case with the Musophagae or plantain-eaters. Nor do I believe that any large group exists in which the sexes of all the species are widely dissimilar in colour: Mr. Wallace informs me that the chatterers of S. America (Cotingidae) offer one of the best instances; but with some of the species, in which the male has a splendid red breast, the female exhibits some red on her breast; and the females of other species shew traces of the green and other colours of the males. Nevertheless we have a near approach to close sexual similarity or dissimilarity throughout several groups: and this, from what has just been said of the fluctuating nature of inheritance, is a somewhat surprising circumstance. But that the same laws should largely prevail with allied animals is not surprising. The domestic fowl has produced a great number of breeds and sub-breeds, and in these the sexes generally differ in plumage; so that it has been noticed as an unusual circumstance when in certain sub-breeds they resemble each other. On the other hand, the domestic pigeon has likewise produced a vast number of distinct breeds and sub-breeds, and in these, with rare exceptions, the two sexes are identically alike. Therefore if other species of Gallus and Columba were domesticated and varied, it would not be rash to predict that similar rules of sexual similarity and dissimilarity, depending on the form of transmission, would hold good in both cases. In like manner the same form of transmission has generally prevailed under nature throughout the same groups, although marked exceptions to this rule occur. Thus within the same family or even genus, the sexes may be identically alike, or very different in colour. Instances have already been given in the same genus, as with sparrows, fly-catchers, thrushes and grouse. In the family of pheasants the sexes of almost all the species are wonderfully dissimilar, but are quite alike in the eared pheasant or Crossoptilon auritum. In two species of Chloephaga, a genus of geese, the male cannot be distinguished from the females, except by size; whilst in two others, the sexes are so unlike that they might easily be mistaken for distinct species. (29. The 'Ibis,' vol. vi. 1864, p. 122.) The laws of inheritance can alone account for the following cases, in which the female acquires, late in life, certain characters proper to the male, and ultimately comes to resemble him more or less completely. Here protection can hardly have come into play. Mr. Blyth informs me that the females of Oriolus melanocephalus and of some allied species, when sufficiently mature to breed, differ considerably in plumage from the adult males; but after the second or third moults they differ only in their beaks having a slight greenish tinge. In the dwarf bitterns (Ardetta), according to the same authority, "the male acquires his final livery at the first moult, the female not before the third or fourth moult; in the meanwhile she presents an intermediate garb, which is ultimately exchanged for the same livery as that of the male." So again the female Falco peregrinus acquires her blue plumage more slowly than the male. Mr. Swinhoe states that with one of the Drongo shrikes (Dicrurus macrocercus) the male, whilst almost a nestling, moults his soft brown plumage and becomes of a uniform glossy greenish-black; but the female retains for a long time the white striae and spots on the axillary feathers; and does not completely assume the uniform black colour of the male for three years. The same excellent observer remarks that in the spring of the second year the female spoon-bill (Platalea) of China resembles the male of the first year, and that apparently it is not until the third spring that she acquires the same adult plumage as that possessed by the male at a much earlier age. The female Bombycilla carolinensis differs very little from the male, but the appendages, which like beads of red sealing-wax ornament the wing-feathers (30. When the male courts the female, these ornaments are vibrated, and "are shewn off to great advantage," on the outstretched wings: A. Leith Adams, 'Field and Forest Rambles,' 1873, p. 153.), are not developed in her so early in life as in the male. In the male of an Indian parrakeet (Palaeornis javanicus) the upper mandible is coral-red from his earliest youth, but in the female, as Mr. Blyth has observed with caged and wild birds, it is at first black and does not become red until the bird is at least a year old, at which age the sexes resemble each other in all respects. Both sexes of the wild turkey are ultimately furnished with a tuft of bristles on the breast, but in two-year-old birds the tuft is about four inches long in the male and hardly apparent in the female; when, however, the latter has reached her fourth year, it is from four to five inches in length. (31. On Ardetta, Translation of Cuvier's 'Regne Animal,' by Mr. Blyth, footnote, p. 159. On the Peregrine Falcon, Mr. Blyth, in Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304. On Dicrurus, 'Ibis,' 1863, p. 44. On the Platalea, 'Ibis,' vol. vi. 1864, p. 366. On the Bombycilla, Audubon's 'Ornitholog. Biography,' vol. i. p. 229. On the Palaeornis, see, also, Jerdon, 'Birds of India,' vol. i. p. 263. On the wild turkey, Audubon, ibid. vol. i. p. 15; but I hear from Judge Caton that in Illinois the female very rarely acquires a tuft. Analogous cases with the females of Petrocossyphus are given by Mr. R. Sharpe, 'Proceedings of the Zoological Society,' 1872, p. 496.) These cases must not be confounded with those where diseased or old females abnormally assume masculine characters, nor with those where fertile females, whilst young, acquire the characters of the male, through variation or some unknown cause. (32. Of these latter cases Mr. Blyth has recorded (Translation of Cuvier's 'Regne Animal,' p. 158) various instances with Lanius, Ruticilla, Linaria, and Anas. Audubon has also recorded a similar case ('Ornitholog. Biography,' vol. v. p. 519) with Pyranga aestiva.) But all these cases have so much in common that they depend, according to the hypothesis of pangenesis, on gemmules derived from each part of the male being present, though latent, in the female; their development following on some slight change in the elective affinities of her constituent tissues. A few words must be added on changes of plumage in relation to the season of the year. From reasons formerly assigned there can be little doubt that the elegant plumes, long pendant feathers, crests, etc., of egrets, herons, and many other birds, which are developed and retained only during the summer, serve for ornamental and nuptial purposes, though common to both sexes. The female is thus rendered more conspicuous during the period of incubation than during the winter; but such birds as herons and egrets would be able to defend themselves. As, however, plumes would probably be inconvenient and certainly of no use during the winter, it is possible that the habit of moulting twice in the year may have been gradually acquired through natural selection for the sake of casting off inconvenient ornaments during the winter. But this view cannot be extended to the many waders, whose summer and winter plumages differ very little in colour. With defenceless species, in which both sexes, or the males alone, become extremely conspicuous during the breeding-season,--or when the males acquire at this season such long wing or tail-feathers as to impede their flight, as with Cosmetornis and Vidua,--it certainly at first appears highly probable that the second moult has been gained for the special purpose of throwing off these ornaments. We must, however, remember that many birds, such as some of the Birds of Paradise, the Argus pheasant and peacock, do not cast their plumes during the winter; and it can hardly be maintained that the constitution of these birds, at least of the Gallinaceae, renders a double moult impossible, for the ptarmigan moults thrice in the year. (33. See Gould's 'Birds of Great Britain.') Hence it must be considered as doubtful whether the many species which moult their ornamental plumes or lose their bright colours during the winter, have acquired this habit on account of the inconvenience or danger which they would otherwise have suffered. I conclude, therefore, that the habit of moulting twice in the year was in most or all cases first acquired for some distinct purpose, perhaps for gaining a warmer winter covering; and that variations in the plumage occurring during the summer were accumulated through sexual selection, and transmitted to the offspring at the same season of the year; that such variations were inherited either by both sexes or by the males alone, according to the form of inheritance which prevailed. This appears more probable than that the species in all cases originally tended to retain their ornamental plumage during the winter, but were saved from this through natural selection, resulting from the inconvenience or danger thus caused. I have endeavoured in this chapter to shew that the arguments are not trustworthy in favour of the view that weapons, bright colours, and various ornaments, are now confined to the males owing to the conversion, by natural selection, of the equal transmission of characters to both sexes, into transmission to the male sex alone. It is also doubtful whether the colours of many female birds are due to the preservation, for the sake of protection, of variations which were from the first limited in their transmission to the female sex. But it will be convenient to defer any further discussion on this subject until I treat, in the following chapter, of the differences in plumage between the young and old. CHAPTER XVI. BIRDS--concluded. The immature plumage in relation to the character of the plumage in both sexes when adult--Six classes of cases--Sexual differences between the males of closely-allied or representative species--The female assuming the characters of the male--Plumage of the young in relation to the summer and winter plumage of the adults--On the increase of beauty in the birds of the world--Protective colouring--Conspicuously coloured birds--Novelty appreciated--Summary of the four chapters on Birds. We must now consider the transmission of characters, as limited by age, in reference to sexual selection. The truth and importance of the principle of inheritance at corresponding ages need not here be discussed, as enough has already been said on the subject. Before giving the several rather complex rules or classes of cases, under which the differences in plumage between the young and the old, as far as known to me, may be included, it will be well to make a few preliminary remarks. With animals of all kinds when the adults differ in colour from the young, and the colours of the latter are not, as far as we can see, of any special service, they may generally be attributed, like various embryological structures, to the retention of a former character. But this view can be maintained with confidence, only when the young of several species resemble each other closely, and likewise resemble other adult species belonging to the same group; for the latter are the living proofs that such a state of things was formerly possible. Young lions and pumas are marked with feeble stripes or rows of spots, and as many allied species both young and old are similarly marked, no believer in evolution will doubt that the progenitor of the lion and puma was a striped animal, and that the young have retained vestiges of the stripes, like the kittens of black cats, which are not in the least striped when grown up. Many species of deer, which when mature are not spotted, are whilst young covered with white spots, as are likewise some few species in the adult state. So again the young in the whole family of pigs (Suidae), and in certain rather distantly allied animals, such as the tapir, are marked with dark longitudinal stripes; but here we have a character apparently derived from an extinct progenitor, and now preserved by the young alone. In all such cases the old have had their colours changed in the course of time, whilst the young have remained but little altered, and this has been effected through the principle of inheritance at corresponding ages. This same principle applies to many birds belonging to various groups, in which the young closely resemble each other, and differ much from their respective adult parents. The young of almost all the Gallinaceae, and of some distantly allied birds such as ostriches, are covered with longitudinally striped down; but this character points back to a state of things so remote that it hardly concerns us. Young cross-bills (Loxia) have at first straight beaks like those of other finches, and in their immature striated plumage they resemble the mature red-pole and female siskin, as well as the young of the goldfinch, greenfinch, and some other allied species. The young of many kinds of buntings (Emberiza) resemble one another, and likewise the adult state of the common bunting, E. miliaria. In almost the whole large group of thrushes the young have their breasts spotted--a character which is retained throughout life by many species, but is quite lost by others, as by the Turdus migratorius. So again with many thrushes, the feathers on the back are mottled before they are moulted for the first time, and this character is retained for life by certain eastern species. The young of many species of shrikes (Lanius), of some woodpeckers, and of an Indian pigeon (Chalcophaps indicus), are transversely striped on the under surface; and certain allied species or whole genera are similarly marked when adult. In some closely-allied and resplendent Indian cuckoos (Chrysococcyx), the mature species differ considerably from one another in colour, but the young cannot be distinguished. The young of an Indian goose (Sarkidiornis melanonotus) closely resemble in plumage an allied genus, Dendrocygna, when mature. (1. In regard to thrushes, shrikes, and woodpeckers, see Mr. Blyth, in Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304; also footnote to his translation of Cuvier's 'Regne Animal,' p. 159. I give the case of Loxia on Mr. Blyth's information. On thrushes, see also Audubon, 'Ornith. Biog.' vol. ii. p. 195. On Chrysococcyx and Chalcophaps, Blyth, as quoted in Jerdon's 'Birds of India,' vol. iii. p. 485. On Sarkidiornis, Blyth, in 'Ibis,' 1867, p. 175.) Similar facts will hereafter be given in regard to certain herons. Young black-grouse (Tetrao tetrix) resemble the young as well as the old of certain other species, for instance the red-grouse or T. scoticus. Finally, as Mr. Blyth, who has attended closely to this subject, has well remarked, the natural affinities of many species are best exhibited in their immature plumage; and as the true affinities of all organic beings depend on their descent from a common progenitor, this remark strongly confirms the belief that the immature plumage approximately shews us the former or ancestral condition of the species. Although many young birds, belonging to various families, thus give us a glimpse of the plumage of their remote progenitors, yet there are many other birds, both dull-coloured and bright-coloured, in which the young closely resemble their parents. In such cases the young of the different species cannot resemble each other more closely than do the parents; nor can they strikingly resemble allied forms when adult. They give us but little insight into the plumage of their progenitors, excepting in so far that, when the young and the old are coloured in the same general manner throughout a whole group of species, it is probable that their progenitors were similarly coloured. We may now consider the classes of cases, under which the differences and resemblances between the plumage of the young and the old, in both sexes or in one sex alone, may be grouped. Rules of this kind were first enounced by Cuvier; but with the progress of knowledge they require some modification and amplification. This I have attempted to do, as far as the extreme complexity of the subject permits, from information derived from various sources; but a full essay on this subject by some competent ornithologist is much needed. In order to ascertain to what extent each rule prevails, I have tabulated the facts given in four great works, namely, by Macgillivray on the birds of Britain, Audubon on those of North America, Jerdon on those of India, and Gould on those of Australia. I may here premise, first, that the several cases or rules graduate into each other; and secondly, that when the young are said to resemble their parents, it is not meant that they are identically alike, for their colours are almost always less vivid, and the feathers are softer and often of a different shape. RULES OR CLASSES OF CASES. I. When the adult male is more beautiful or conspicuous than the adult female, the young of both sexes in their first plumage closely resemble the adult female, as with the common fowl and peacock; or, as occasionally occurs, they resemble her much more closely than they do the adult male. II. When the adult female is more conspicuous than the adult male, as sometimes though rarely occurs, the young of both sexes in their first plumage resemble the adult male. III. When the adult male resembles the adult female, the young of both sexes have a peculiar first plumage of their own, as with the robin. IV. When the adult male resembles the adult female, the young of both sexes in their first plumage resemble the adults, as with the kingfisher, many parrots, crows, hedge-warblers. V. When the adults of both sexes have a distinct winter and summer plumage, whether or not the male differs from the female, the young resemble the adults of both sexes in their winter dress, or much more rarely in their summer dress, or they resemble the females alone. Or the young may have an intermediate character; or again they may differ greatly from the adults in both their seasonal plumages. VI. In some few cases the young in their first plumage differ from each other according to sex; the young males resembling more or less closely the adult males, and the young females more or less closely the adult females. CLASS I. In this class, the young of both sexes more or less closely resemble the adult female, whilst the adult male differs from the adult female, often in the most conspicuous manner. Innumerable instances in all Orders could be given; it will suffice to call to mind the common pheasant, duck, and house-sparrow. The cases under this class graduate into others. Thus the two sexes when adult may differ so slightly, and the young so slightly from the adults, that it is doubtful whether such cases ought to come under the present, or under the third or fourth classes. So again the young of the two sexes, instead of being quite alike, may differ in a slight degree from each other, as in our sixth class. These transitional cases, however, are few, or at least are not strongly pronounced, in comparison with those which come strictly under the present class. The force of the present law is well shewn in those groups, in which, as a general rule, the two sexes and the young are all alike; for when in these groups the male does differ from the female, as with certain parrots, kingfishers, pigeons, etc., the young of both sexes resemble the adult female. (2. See, for instance, Mr. Gould's account ('Handbook to the Birds of Australia,' vol. i. p. 133) of Cyanalcyon (one of the Kingfishers), in which, however, the young male, though resembling the adult female, is less brilliantly coloured. In some species of Dacelo the males have blue tails, and the females brown ones; and Mr. R.B. Sharpe informs me that the tail of the young male of D. gaudichaudi is at first brown. Mr. Gould has described (ibid. vol. ii. pp. 14, 20, 37) the sexes and the young of certain black Cockatoos and of the King Lory, with which the same rule prevails. Also Jerdon ('Birds of India,' vol. i. p. 260) on the Palaeornis rosa, in which the young are more like the female than the male. See Audubon ('Ornithological Biography,' vol. ii. p. 475) on the two sexes and the young of Columba passerina.) We see the same fact exhibited still more clearly in certain anomalous cases; thus the male of Heliothrix auriculata (one of the humming-birds) differs conspicuously from the female in having a splendid gorget and fine ear-tufts, but the female is remarkable from having a much longer tail than that of the male; now the young of both sexes resemble (with the exception of the breast being spotted with bronze) the adult female in all other respects, including the length of her tail, so that the tail of the male actually becomes shorter as he reaches maturity, which is a most unusual circumstance. (3. I owe this information to Mr. Gould, who shewed me the specimens; see also his 'Introduction to the Trochilidae,' 1861, p. 120.) Again, the plumage of the male goosander (Mergus merganser) is more conspicuously coloured than that of the female, with the scapular and secondary wing-feathers much longer; but differently from what occurs, as far as I know, in any other bird, the crest of the adult male, though broader than that of the female, is considerably shorter, being only a little above an inch in length; the crest of the female being two and a half inches long. Now the young of both sexes entirely resemble the adult female, so that their crests are actually of greater length, though narrower, than in the adult male. (4. Macgillivray, 'Hist. Brit. Birds,' vol. v. pp. 207-214.) When the young and the females closely resemble each other and both differ from the males, the most obvious conclusion is that the males alone have been modified. Even in the anomalous cases of the Heliothrix and Mergus, it is probable that originally both adult sexes were furnished--the one species with a much elongated tail, and the other with a much elongated crest--these characters having since been partially lost by the adult males from some unexplained cause, and transmitted in their diminished state to their male offspring alone, when arrived at the corresponding age of maturity. The belief that in the present class the male alone has been modified, as far as the differences between the male and the female together with her young are concerned, is strongly supported by some remarkable facts recorded by Mr. Blyth (5. See his admirable paper in the 'Journal of the Asiatic Soc. of Bengal,' vol. xix. 1850, p. 223; see also Jerdon, 'Birds of India,' vol. i. introduction, p. xxix. In regard to Tanysiptera, Prof. Schlegel told Mr. Blyth that he could distinguish several distinct races, solely by comparing the adult males.), with respect to closely-allied species which represent each other in distinct countries. For with several of these representative species the adult males have undergone a certain amount of change and can be distinguished; the females and the young from the distinct countries being indistinguishable, and therefore absolutely unchanged. This is the case with certain Indian chats (Thamnobia), with certain honey-suckers (Nectarinia), shrikes (Tephrodornis), certain kingfishers (Tanysiptera), Kalij pheasants (Gallophasis), and tree-partridges (Arboricola). In some analogous cases, namely with birds having a different summer and winter plumage, but with the two sexes nearly alike, certain closely-allied species can easily be distinguished in their summer or nuptial plumage, yet are indistinguishable in their winter as well as in their immature plumage. This is the case with some of the closely-allied Indian wagtails or Motacillae. Mr. Swinhoe (6. See also Mr. Swinhoe, in 'Ibis,' July 1863, p. 131; and a previous paper, with an extract from a note by Mr. Blyth, in 'Ibis,' January, 1861, p. 25.) informs me that three species of Ardeola, a genus of herons, which represent one another on separate continents, are "most strikingly different" when ornamented with their summer plumes, but are hardly, if at all, distinguishable during the winter. The young also of these three species in their immature plumage closely resemble the adults in their winter dress. This case is all the more interesting, because with two other species of Ardeola both sexes retain, during the winter and summer, nearly the same plumage as that possessed by the three first species during the winter and in their immature state; and this plumage, which is common to several distinct species at different ages and seasons, probably shews us how the progenitors of the genus were coloured. In all these cases, the nuptial plumage which we may assume was originally acquired by the adult males during the breeding-season, and transmitted to the adults of both sexes at the corresponding season, has been modified, whilst the winter and immature plumages have been left unchanged. The question naturally arises, how is it that in these latter cases the winter plumage of both sexes, and in the former cases the plumage of the adult females, as well as the immature plumage of the young, have not been at all affected? The species which represent each other in distinct countries will almost always have been exposed to somewhat different conditions, but we can hardly attribute to this action the modification of the plumage in the males alone, seeing that the females and the young, though similarly exposed, have not been affected. Hardly any fact shews us more clearly how subordinate in importance is the direct action of the conditions of life, in comparison with the accumulation through selection of indefinite variations, than the surprising difference between the sexes of many birds; for both will have consumed the same food, and have been exposed to the same climate. Nevertheless we are not precluded from believing that in the course of time new conditions may produce some direct effect either on both sexes, or from their constitutional differences chiefly on one sex. We see only that this is subordinate in importance to the accumulated results of selection. Judging, however, from a wide-spread analogy, when a species migrates into a new country (and this must precede the formation of representative species), the changed conditions to which they will almost always have been exposed will cause them to undergo a certain amount of fluctuating variability. In this case sexual selection, which depends on an element liable to change--the taste or admiration of the female--will have had new shades of colour or other differences to act on and accumulate; and as sexual selection is always at work, it would (from what we know of the results on domestic animals of man's unintentional selection), be surprising if animals inhabiting separate districts, which can never cross and thus blend their newly-acquired characters, were not, after a sufficient lapse of time, differently modified. These remarks likewise apply to the nuptial or summer plumage, whether confined to the males, or common to both sexes. Although the females of the above closely-allied or representative species, together with their young, differ hardly at all from one another, so that the males alone can be distinguished, yet the females of most species within the same genus obviously differ from each other. The differences, however, are rarely as great as between the males. We see this clearly in the whole family of the Gallinaceae: the females, for instance, of the common and Japan pheasant, and especially of the gold and Amherst pheasant --of the silver pheasant and the wild fowl--resemble one another very closely in colour, whilst the males differ to an extraordinary degree. So it is with the females of most of the Cotingidae, Fringillidae, and many other families. There can indeed be no doubt that, as a general rule, the females have been less modified than the males. Some few birds, however, offer a singular and inexplicable exception; thus the females of Paradisea apoda and P. papuana differ from each other more than do their respective males (7. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 394.); the female of the latter species having the under surface pure white, whilst the female P. apoda is deep brown beneath. So, again, as I hear from Professor Newton, the males of two species of Oxynotus (shrikes), which represent each other in the islands of Mauritius and Bourbon (8. These species are described with coloured figures, by M. F. Pollen, in 'Ibis,' 1866, p. 275.), differ but little in colour, whilst the females differ much. In the Bourbon species the female appears to have partially retained an immature condition of plumage, for at first sight she "might be taken for the young of the Mauritian species." These differences may be compared with those inexplicable ones, which occur independently of man's selection in certain sub-breeds of the game-fowl, in which the females are very different, whilst the males can hardly be distinguished. (9. 'Variation of Animals,' etc., vol. i. p. 251.) As I account so largely by sexual selection for the differences between the males of allied species, how can the differences between the females be accounted for in all ordinary cases? We need not here consider the species which belong to distinct genera; for with these, adaptation to different habits of life, and other agencies, will have come into play. In regard to the differences between the females within the same genus, it appears to me almost certain, after looking through various large groups, that the chief agent has been the greater or less transference to the female of the characters acquired by the males through sexual selection. In the several British finches, the two sexes differ either very slightly or considerably; and if we compare the females of the greenfinch, chaffinch, goldfinch, bullfinch, crossbill, sparrow, etc., we shall see that they differ from one another chiefly in the points in which they partially resemble their respective males; and the colours of the males may safely be attributed to sexual selection. With many gallinaceous species the sexes differ to an extreme degree, as with the peacock, pheasant, and fowl, whilst with other species there has been a partial or even complete transference of character from the male to the female. The females of the several species of Polyplectron exhibit in a dim condition, and chiefly on the tail, the splendid ocelli of their males. The female partridge differs from the male only in the red mark on her breast being smaller; and the female wild turkey only in her colours being much duller. In the guinea-fowl the two sexes are indistinguishable. There is no improbability in the plain, though peculiarly spotted plumage of this latter bird having been acquired through sexual selection by the males, and then transmitted to both sexes; for it is not essentially different from the much more beautifully spotted plumage, characteristic of the males alone of the Tragopan pheasants. It should be observed that, in some instances, the transference of characters from the male to the female has been effected apparently at a remote period, the male having subsequently undergone great changes, without transferring to the female any of his later-gained characters. For instance, the female and the young of the black-grouse (Tetrao tetrix) resemble pretty closely both sexes and the young of the red-grouse (T. scoticus); and we may consequently infer that the black-grouse is descended from some ancient species, of which both sexes were coloured in nearly the same manner as the red-grouse. As both sexes of this latter species are more distinctly barred during the breeding-season than at any other time, and as the male differs slightly from the female in his more strongly-pronounced red and brown tints (10. Macgillivray, 'History of British Birds,' vol. i. pp. 172-174.), we may conclude that his plumage has been influenced by sexual selection, at least to a certain extent. If so, we may further infer that nearly similar plumage of the female black-grouse was similarly produced at some former period. But since this period the male black-grouse has acquired his fine black plumage, with his forked and outwardly-curled tail-feathers; but of these characters there has hardly been any transference to the female, excepting that she shews in her tail a trace of the curved fork. We may therefore conclude that the females of distinct though allied species have often had their plumage rendered more or less different by the transference in various degrees of characters acquired by the males through sexual selection, both during former and recent times. But it deserves especial attention that brilliant colours have been transferred much more rarely than other tints. For instance, the male of the red-throated blue-breast (Cyanecula suecica) has a rich blue breast, including a sub-triangular red mark; now marks of nearly the same shape have been transferred to the female, but the central space is fulvous instead of red, and is surrounded by mottled instead of blue feathers. The Gallinaceae offer many analogous cases; for none of the species, such as partridges, quails, guinea-fowls, etc., in which the colours of the plumage have been largely transferred from the male to the female, are brilliantly coloured. This is well exemplified with the pheasants, in which the male is generally so much more brilliant than the female; but with the Eared and Cheer pheasants (Crossoptilon auritum and Phasianus wallichii) the sexes closely resemble each other and their colours are dull. We may go so far as to believe that if any part of the plumage in the males of these two pheasants had been brilliantly coloured, it would not have been transferred to the females. These facts strongly support Mr. Wallace's view that with birds which are exposed to much danger during incubation, the transference of bright colours from the male to the female has been checked through natural selection. We must not, however, forget that another explanation, before given, is possible; namely, that the males which varied and became bright, whilst they were young and inexperienced, would have been exposed to much danger, and would generally have been destroyed; the older and more cautious males, on the other hand, if they varied in a like manner, would not only have been able to survive, but would have been favoured in their rivalry with other males. Now variations occurring late in life tend to be transmitted exclusively to the same sex, so that in this case extremely bright tints would not have been transmitted to the females. On the other hand, ornaments of a less conspicuous kind, such as those possessed by the Eared and Cheer pheasants, would not have been dangerous, and if they appeared during early youth, would generally have been transmitted to both sexes. In addition to the effects of the partial transference of characters from the males to the females, some of the differences between the females of closely allied species may be attributed to the direct or definite action of the conditions of life. (11. See, on this subject, chap. xxiii. in the 'Variation of Animals and Plants under Domestication.') With the males, any such action would generally have been masked by the brilliant colours gained through sexual selection; but not so with the females. Each of the endless diversities in plumage which we see in our domesticated birds is, of course, the result of some definite cause; and under natural and more uniform conditions, some one tint, assuming that it was in no way injurious, would almost certainly sooner or later prevail. The free intercrossing of the many individuals belonging to the same species would ultimately tend to make any change of colour, thus induced, uniform in character. No one doubts that both sexes of many birds have had their colours adapted for the sake of protection; and it is possible that the females alone of some species may have been modified for this end. Although it would be a difficult, perhaps an impossible process, as shewn in the last chapter, to convert one form of transmission into another through selection, there would not be the least difficulty in adapting the colours of the female, independently of those of the male, to surrounding objects, through the accumulation of variations which were from the first limited in their transmission to the female sex. If the variations were not thus limited, the bright tints of the male would be deteriorated or destroyed. Whether the females alone of many species have been thus specially modified, is at present very doubtful. I wish I could follow Mr. Wallace to the full extent; for the admission would remove some difficulties. Any variations which were of no service to the female as a protection would be at once obliterated, instead of being lost simply by not being selected, or from free intercrossing, or from being eliminated when transferred to the male and in any way injurious to him. Thus the plumage of the female would be kept constant in character. It would also be a relief if we could admit that the obscure tints of both sexes of many birds had been acquired and preserved for the sake of protection,--for example, of the hedge-warbler or kitty-wren (Accentor modularis and Troglodytes vulgaris), with respect to which we have no sufficient evidence of the action of sexual selection. We ought, however, to be cautious in concluding that colours which appear to us dull, are not attractive to the females of certain species; we should bear in mind such cases as that of the common house-sparrow, in which the male differs much from the female, but does not exhibit any bright tints. No one probably will dispute that many gallinaceous birds which live on the open ground, have acquired their present colours, at least in part, for the sake of protection. We know how well they are thus concealed; we know that ptarmigans, whilst changing from their winter to their summer plumage, both of which are protective, suffer greatly from birds of prey. But can we believe that the very slight differences in tints and markings between, for instance, the female black-grouse and red-grouse serve as a protection? Are partridges, as they are now coloured, better protected than if they had resembled quails? Do the slight differences between the females of the common pheasant, the Japan and gold pheasants, serve as a protection, or might not their plumages have been interchanged with impunity? From what Mr. Wallace has observed of the habits of certain gallinaceous birds in the East, he thinks that such slight differences are beneficial. For myself, I will only say that I am not convinced. Formerly when I was inclined to lay much stress on protection as accounting for the duller colours of female birds, it occurred to me that possibly both sexes and the young might aboriginally have been equally bright coloured; but that subsequently, the females from the danger incurred during incubation, and the young from being inexperienced, had been rendered dull as a protection. But this view is not supported by any evidence, and is not probable; for we thus in imagination expose during past times the females and the young to danger, from which it has subsequently been necessary to shield their modified descendants. We have, also, to reduce, through a gradual process of selection, the females and the young to almost exactly the same tints and markings, and to transmit them to the corresponding sex and period of life. On the supposition that the females and the young have partaken during each stage of the process of modification of a tendency to be as brightly coloured as the males, it is also a somewhat strange fact that the females have never been rendered dull-coloured without the young participating in the same change; for there are no instances, as far as I can discover, of species with the females dull and the young bright coloured. A partial exception, however, is offered by the young of certain woodpeckers, for they have "the whole upper part of the head tinged with red," which afterwards either decreases into a mere circular red line in the adults of both sexes, or quite disappears in the adult females. (12. Audubon, 'Ornith. Biography,' vol. i. p. 193. Macgillivray, 'History of British Birds,' vol. iii. p. 85. See also the case before given of Indopicus carlotta.) Finally, with respect to our present class of cases, the most probable view appears to be that successive variations in brightness or in other ornamental characters, occurring in the males at a rather late period of life have alone been preserved; and that most or all of these variations, owing to the late period of life at which they appeared, have been from the first transmitted only to the adult male offspring. Any variations in brightness occurring in the females or in the young, would have been of no service to them, and would not have been selected; and moreover, if dangerous, would have been eliminated. Thus the females and the young will either have been left unmodified, or (as is much more common) will have been partially modified by receiving through transference from the males some of his successive variations. Both sexes have perhaps been directly acted on by the conditions of life to which they have long been exposed: but the females from not being otherwise much modified, will best exhibit any such effects. These changes and all others will have been kept uniform by the free intercrossing of many individuals. In some cases, especially with ground birds, the females and the young may possibly have been modified, independently of the males, for the sake of protection, so as to have acquired the same dull-coloured plumage. CLASS II. WHEN THE ADULT FEMALE IS MORE CONSPICUOUS THAN THE ADULT MALE, THE YOUNG OF BOTH SEXES IN THEIR FIRST PLUMAGE RESEMBLE THE ADULT MALE. This class is exactly the reverse of the last, for the females are here brighter coloured or more conspicuous than the males; and the young, as far as they are known, resemble the adult males instead of the adult females. But the difference between the sexes is never nearly so great as with many birds in the first class, and the cases are comparatively rare. Mr. Wallace, who first called attention to the singular relation which exists between the less bright colours of the males and their performing the duties of incubation, lays great stress on this point (13. 'Westminster Review,' July 1867, and A. Murray, 'Journal of Travel,' 1868, p. 83.), as a crucial test that obscure colours have been acquired for the sake of protection during the period of nesting. A different view seems to me more probable. As the cases are curious and not numerous, I will briefly give all that I have been able to find. In one section of the genus Turnix, quail-like birds, the female is invariably larger than the male (being nearly twice as large in one of the Australian species), and this is an unusual circumstance with the Gallinaceae. In most of the species the female is more distinctly coloured and brighter than the male (14. For the Australian species, see Gould's 'Handbook,' etc., vol. ii. pp. 178, 180, 186, and 188. In the British Museum specimens of the Australian Plain-wanderer (Pedionomus torquatus) may be seen, shewing similar sexual differences.), but in some few species the sexes are alike. In Turnix taigoor of India the male "wants the black on the throat and neck, and the whole tone of the plumage is lighter and less pronounced than that of the female." The female appears to be noisier, and is certainly much more pugnacious than the male; so that the females and not the males are often kept by the natives for fighting, like game-cocks. As male birds are exposed by the English bird-catchers for a decoy near a trap, in order to catch other males by exciting their rivalry, so the females of this Turnix are employed in India. When thus exposed the females soon begin their "loud purring call, which can be heard a long way off, and any females within ear-shot run rapidly to the spot, and commence fighting with the caged bird." In this way from twelve to twenty birds, all breeding females, may be caught in the course of a single day. The natives assert that the females after laying their eggs associate in flocks, and leave the males to sit on them. There is no reason to doubt the truth of this assertion, which is supported by some observations made in China by Mr. Swinhoe. (15. Jerdon, 'Birds of India,' vol. iii. p. 596. Mr. Swinhoe, in 'Ibis,' 1865, p. 542; 1866, pp. 131, 405.) Mr. Blyth believes, that the young of both sexes resemble the adult male. [Fig. 62. Rhynchaea capensis (from Brehm).] The females of the three species of Painted Snipes (Rhynchaea, Fig. 62) "are not only larger but much more richly coloured than the males." (16. Jerdon, 'Birds of India,' vol. iii. p. 677.) With all other birds in which the trachea differs in structure in the two sexes it is more developed and complex in the male than in the female; but in the Rhynchaea australis it is simple in the male, whilst in the female it makes four distinct convolutions before entering the lungs. (17. Gould's 'Handbook to the Birds of Australia,' vol. ii. p. 275.) The female therefore of this species has acquired an eminently masculine character. Mr. Blyth ascertained, by examining many specimens, that the trachea is not convoluted in either sex of R. bengalensis, which species resembles R. australis so closely, that it can hardly be distinguished except by its shorter toes. This fact is another striking instance of the law that secondary sexual characters are often widely different in closely-allied forms, though it is a very rare circumstance when such differences relate to the female sex. The young of both sexes of R. bengalensis in their first plumage are said to resemble the mature male. (18. 'The Indian Field,' Sept. 1858, p. 3.) There is also reason to believe that the male undertakes the duty of incubation, for Mr. Swinhoe (19. 'Ibis,' 1866, p. 298.) found the females before the close of the summer associated in flocks, as occurs with the females of the Turnix. The females of Phalaropus fulicarius and P. hyperboreus are larger, and in their summer plumage "more gaily attired than the males." But the difference in colour between the sexes is far from conspicuous. According to Professor Steenstrup, the male alone of P. fulicarius undertakes the duty of incubation; this is likewise shewn by the state of his breast-feathers during the breeding-season. The female of the dotterel plover (Eudromias morinellus) is larger than the male, and has the red and black tints on the lower surface, the white crescent on the breast, and the stripes over the eyes, more strongly pronounced. The male also takes at least a share in hatching the eggs; but the female likewise attends to the young. (20. For these several statements, see Mr. Gould's 'Birds of Great Britain.' Prof. Newton informs me that he has long been convinced, from his own observations and from those of others, that the males of the above-named species take either the whole or a large share of the duties of incubation, and that they "shew much greater devotion towards their young, when in danger, than do the females." So it is, as he informs me, with Limosa lapponica and some few other Waders, in which the females are larger and have more strongly contrasted colours than the males.) I have not been able to discover whether with these species the young resemble the adult males more closely than the adult females; for the comparison is somewhat difficult to make on account of the double moult. Turning now to the ostrich Order: the male of the common cassowary (Casuarius galeatus) would be thought by any one to be the female, from his smaller size and from the appendages and naked skin about his head being much less brightly coloured; and I am informed by Mr. Bartlett that in the Zoological Gardens, it is certainly the male alone who sits on the eggs and takes care of the young. (21. The natives of Ceram (Wallace, 'Malay Archipelago,' vol. ii. p. 150) assert that the male and female sit alternately on the eggs; but this assertion, as Mr. Bartlett thinks, may be accounted for by the female visiting the nest to lay her eggs.) The female is said by Mr. T.W. Wood (22. The 'Student,' April 1870, p. 124.) to exhibit during the breeding-season a most pugnacious disposition; and her wattles then become enlarged and more brilliantly coloured. So again the female of one of the emus (Dromoeus irroratus) is considerably larger than the male, and she possesses a slight top-knot, but is otherwise indistinguishable in plumage. She appears, however, "to have greater power, when angry or otherwise excited, of erecting, like a turkey-cock, the feathers of her neck and breast. She is usually the more courageous and pugilistic. She makes a deep hollow guttural boom especially at night, sounding like a small gong. The male has a slenderer frame and is more docile, with no voice beyond a suppressed hiss when angry, or a croak." He not only performs the whole duty of incubation, but has to defend the young from their mother; "for as soon as she catches sight of her progeny she becomes violently agitated, and notwithstanding the resistance of the father appears to use her utmost endeavours to destroy them. For months afterwards it is unsafe to put the parents together, violent quarrels being the inevitable result, in which the female generally comes off conqueror." (23. See the excellent account of the habits of this bird under confinement, by Mr. A.W. Bennett, in 'Land and Water,' May 1868, p. 233.) So that with this emu we have a complete reversal not only of the parental and incubating instincts, but of the usual moral qualities of the two sexes; the females being savage, quarrelsome, and noisy, the males gentle and good. The case is very different with the African ostrich, for the male is somewhat larger than the female and has finer plumes with more strongly contrasted colours; nevertheless he undertakes the whole duty of incubation. (24. Mr. Sclater, on the incubation of the Struthiones, 'Proc. Zool. Soc.' June 9, 1863. So it is with the Rhea darwinii: Captain Musters says ('At Home with the Patagonians,' 1871, p. 128), that the male is larger, stronger and swifter than the female, and of slightly darker colours; yet he takes sole charge of the eggs and of the young, just as does the male of the common species of Rhea.) I will specify the few other cases known to me, in which the female is more conspicuously coloured than the male, although nothing is known about the manner of incubation. With the carrion-hawk of the Falkland Islands (Milvago leucurus) I was much surprised to find by dissection that the individuals, which had all their tints strongly pronounced, with the cere and legs orange-coloured, were the adult females; whilst those with duller plumage and grey legs were the males or the young. In an Australian tree-creeper (Climacteris erythrops) the female differs from the male in "being adorned with beautiful, radiated, rufous markings on the throat, the male having this part quite plain." Lastly, in an Australian night-jar "the female always exceeds the male in size and in the brilliance of her tints; the males, on the other hand, have two white spots on the primaries more conspicuous than in the female." (25. For the Milvago, see 'Zoology of the Voyage of the "Beagle," Birds,' 1841, p. 16. For the Climacteris and night-jar (Eurostopodus), see Gould's 'Handbook to the Birds of Australia,' vol. i. pp. 602 and 97. The New Zealand shieldrake (Tadorna variegata) offers a quite anomalous case; the head of the female is pure white, and her back is redder than that of the male; the head of the male is of a rich dark bronzed colour, and his back is clothed with finely pencilled slate-coloured feathers, so that altogether he may be considered as the more beautiful of the two. He is larger and more pugnacious than the female, and does not sit on the eggs. So that in all these respects this species comes under our first class of cases; but Mr. Sclater ('Proceedings of the Zoological Society,' 1866, p. 150) was much surprised to observe that the young of both sexes, when about three months old, resembled in their dark heads and necks the adult males, instead of the adult females; so that it would appear in this case that the females have been modified, whilst the males and the young have retained a former state of plumage.) We thus see that the cases in which female birds are more conspicuously coloured than the males, with the young in their immature plumage resembling the adult males instead of the adult females, as in the previous class, are not numerous, though they are distributed in various Orders. The amount of difference, also, between the sexes is incomparably less than that which frequently occurs in the last class; so that the cause of the difference, whatever it may have been, has here acted on the females either less energetically or less persistently than on the males in the last class. Mr. Wallace believes that the males have had their colours rendered less conspicuous for the sake of protection during the period of incubation; but the difference between the sexes in hardly any of the foregoing cases appears sufficiently great for this view to be safely accepted. In some of the cases, the brighter tints of the female are almost confined to the lower surface, and the males, if thus coloured, would not have been exposed to danger whilst sitting on the eggs. It should also be borne in mind that the males are not only in a slight degree less conspicuously coloured than the females, but are smaller and weaker. They have, moreover, not only acquired the maternal instinct of incubation, but are less pugnacious and vociferous than the females, and in one instance have simpler vocal organs. Thus an almost complete transposition of the instincts, habits, disposition, colour, size, and of some points of structure, has been effected between the two sexes. Now if we might assume that the males in the present class have lost some of that ardour which is usual to their sex, so that they no longer search eagerly for the females; or, if we might assume that the females have become much more numerous than the males--and in the case of one Indian Turnix the females are said to be "much more commonly met with than the males" (26. Jerdon, 'Birds of India,' vol. iii. p. 598.)--then it is not improbable that the females would have been led to court the males, instead of being courted by them. This indeed is the case to a certain extent with some birds, as we have seen with the peahen, wild turkey, and certain kinds of grouse. Taking as our guide the habits of most male birds, the greater size and strength as well as the extraordinary pugnacity of the females of the Turnix and emu, must mean that they endeavour to drive away rival females, in order to gain possession of the male; and on this view all the facts become clear; for the males would probably be most charmed or excited by the females which were the most attractive to them by their bright colours, other ornaments, or vocal powers. Sexual selection would then do its work, steadily adding to the attractions of the females; the males and the young being left not at all, or but little modified. CLASS III. WHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES HAVE A PECULIAR FIRST PLUMAGE OF THEIR OWN. In this class the sexes when adult resemble each other, and differ from the young. This occurs with many birds of many kinds. The male robin can hardly be distinguished from the female, but the young are widely different, with their mottled dusky-olive and brown plumage. The male and female of the splendid scarlet ibis are alike, whilst the young are brown; and the scarlet colour, though common to both sexes, is apparently a sexual character, for it is not well developed in either sex under confinement; and a loss of colour often occurs with brilliant males when they are confined. With many species of herons the young differ greatly from the adults; and the summer plumage of the latter, though common to both sexes, clearly has a nuptial character. Young swans are slate-coloured, whilst the mature birds are pure white; but it would be superfluous to give additional instances. These differences between the young and the old apparently depend, as in the last two classes, on the young having retained a former or ancient state of plumage, whilst the old of both sexes have acquired a new one. When the adults are bright coloured, we may conclude from the remarks just made in relation to the scarlet ibis and to many herons, and from the analogy of the species in the first class, that such colours have been acquired through sexual selection by the nearly mature males; but that, differently from what occurs in the first two classes, the transmission, though limited to the same age, has not been limited to the same sex. Consequently, the sexes when mature resemble each other and differ from the young. CLASS IV. WHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES IN THEIR FIRST PLUMAGE RESEMBLE THE ADULTS. In this class the young and the adults of both sexes, whether brilliantly or obscurely coloured, resemble each other. Such cases are, I think, more common than those in the last class. We have in England instances in the kingfisher, some woodpeckers, the jay, magpie, crow, and many small dull-coloured birds, such as the hedge-warbler or kitty-wren. But the similarity in plumage between the young and the old is never complete, and graduates away into dissimilarity. Thus the young of some members of the kingfisher family are not only less vividly coloured than the adults, but many of the feathers on the lower surface are edged with brown (27. Jerdon, 'Birds of India,' vol. i. pp. 222, 228. Gould's 'Handbook to the Birds of Australia,' vol. i. pp. 124, 130.),--a vestige probably of a former state of the plumage. Frequently in the same group of birds, even within the same genus, for instance in an Australian genus of parrakeets (Platycercus), the young of some species closely resemble, whilst the young of other species differ considerably, from their parents of both sexes, which are alike. (28. Gould, ibid. vol. ii. pp. 37, 46, 56.) Both sexes and the young of the common jay are closely similar; but in the Canada jay (Perisoreus canadensis) the young differ so much from their parents that they were formerly described as distinct species. (29. Audubon, 'Ornith. Biography,' vol. ii. p. 55.) I may remark before proceeding that, under the present and next two classes of cases, the facts are so complex and the conclusions so doubtful, that any one who feels no especial interest in the subject had better pass them over. The brilliant or conspicuous colours which characterise many birds in the present class, can rarely or never be of service to them as a protection; so that they have probably been gained by the males through sexual selection, and then transferred to the females and the young. It is, however, possible that the males may have selected the more attractive females; and if these transmitted their characters to their offspring of both sexes, the same results would follow as from the selection of the more attractive males by the females. But there is evidence that this contingency has rarely, if ever, occurred in any of those groups of birds in which the sexes are generally alike; for, if even a few of the successive variations had failed to be transmitted to both sexes, the females would have slightly exceeded the males in beauty. Exactly the reverse occurs under nature; for, in almost every large group in which the sexes generally resemble each other, the males of some few species are in a slight degree more brightly coloured than the females. It is again possible that the females may have selected the more beautiful males, these males having reciprocally selected the more beautiful females; but it is doubtful whether this double process of selection would be likely to occur, owing to the greater eagerness of one sex than the other, and whether it would be more efficient than selection on one side alone. It is, therefore, the most probable view that sexual selection has acted, in the present class, as far as ornamental characters are concerned, in accordance with the general rule throughout the animal kingdom, that is, on the males; and that these have transmitted their gradually-acquired colours, either equally or almost equally, to their offspring of both sexes. Another point is more doubtful, namely, whether the successive variations first appeared in the males after they had become nearly mature, or whilst quite young. In either case sexual selection must have acted on the male when he had to compete with rivals for the possession of the female; and in both cases the characters thus acquired have been transmitted to both sexes and all ages. But these characters if acquired by the males when adult, may have been transmitted at first to the adults alone, and at some subsequent period transferred to the young. For it is known that, when the law of inheritance at corresponding ages fails, the offspring often inherit characters at an earlier age than that at which they first appeared in their parents. (30. 'Variation of Animals and Plants under Domestication,' vol. ii. p. 79.) Cases apparently of this kind have been observed with birds in a state of nature. For instance Mr. Blyth has seen specimens of Lanius rufus and of Colymbus glacialis which had assumed whilst young, in a quite anomalous manner, the adult plumage of their parents. (31. 'Charlesworth's Magazine of Natural History,' vol. i. 1837, pp. 305, 306.) Again, the young of the common swan (Cygnus olor) do not cast off their dark feathers and become white until eighteen months or two years old; but Dr. F. Forel has described the case of three vigorous young birds, out of a brood of four, which were born pure white. These young birds were not albinos, as shewn by the colour of their beaks and legs, which nearly resembled the same parts in the adults. (32. 'Bulletin de la Soc. Vaudoise des Sc. Nat.' vol. x. 1869, p. 132. The young of the Polish swan, Cygnus immutabilis of Yarrell, are always white; but this species, as Mr. Sclater informs me, is believed to be nothing more than a variety of the domestic swan (Cygnus olor).) It may be worth while to illustrate the above three modes by which, in the present class, the two sexes and the young may have come to resemble each other, by the curious case of the genus Passer. (33. I am indebted to Mr. Blyth for information in regard to this genus. The sparrow of Palestine belongs to the sub-genus Petronia.) In the house-sparrow (P. domesticus) the male differs much from the female and from the young. The young and the females are alike, and resemble to a large extent both sexes and the young of the sparrow of Palestine (P. brachydactylus), as well as of some allied species. We may therefore assume that the female and young of the house-sparrow approximately shew us the plumage of the progenitor of the genus. Now with the tree-sparrow (P. montanus) both sexes and the young closely resemble the male of the house-sparrow; so that they have all been modified in the same manner, and all depart from the typical colouring of their early progenitor. This may have been effected by a male ancestor of the tree-sparrow having varied, firstly, when nearly mature; or, secondly, whilst quite young, and by having in either case transmitted his modified plumage to the females and the young; or, thirdly, he may have varied when adult and transmitted his plumage to both adult sexes, and, owing to the failure of the law of inheritance at corresponding ages, at some subsequent period to his young. It is impossible to decide which of these three modes has generally prevailed throughout the present class of cases. That the males varied whilst young, and transmitted their variations to their offspring of both sexes, is the most probable. I may here add that I have, with little success, endeavoured, by consulting various works, to decide how far the period of variation in birds has generally determined the transmission of characters to one sex or to both. The two rules, often referred to (namely, that variations occurring late in life are transmitted to one and the same sex, whilst those which occur early in life are transmitted to both sexes), apparently hold good in the first (34. For instance, the males of Tanagra aestiva and Fringilla cyanea require three years, the male of Fringilla ciris four years, to complete their beautiful plumage. (See Audubon, 'Ornith. Biography,' vol. i. pp. 233, 280, 378). The Harlequin duck takes three years (ibid. vol. iii. p. 614). The male of the Gold pheasant, as I hear from Mr. Jenner Weir, can be distinguished from the female when about three months old, but he does not acquire his full splendour until the end of the September in the following year.), second, and fourth classes of cases; but they fail in the third, often in the fifth (35. Thus the Ibis tantalus and Grus americanus take four years, the Flamingo several years, and the Ardea ludovicana two years, before they acquire their perfect plumage. See Audubon, ibid. vol. i. p. 221; vol. iii. pp. 133, 139, 211.), and in the sixth small class. They apply, however, as far as I can judge, to a considerable majority of the species; and we must not forget the striking generalisation by Dr. W. Marshall with respect to the protuberances on the heads of birds. Whether or not the two rules generally hold good, we may conclude from the facts given in the eighth chapter, that the period of variation is one important element in determining the form of transmission. With birds it is difficult to decide by what standard we ought to judge of the earliness or lateness of the period of variation, whether by the age in reference to the duration of life, or to the power of reproduction, or to the number of moults through which the species passes. The moulting of birds, even within the same family, sometimes differs much without any assignable cause. Some birds moult so early, that nearly all the body feathers are cast off before the first wing-feathers are fully grown; and we cannot believe that this was the primordial state of things. When the period of moulting has been accelerated, the age at which the colours of the adult plumage are first developed will falsely appear to us to be earlier than it really is. This may be illustrated by the practice followed by some bird-fanciers, who pull out a few feathers from the breast of nestling bullfinches, and from the head or neck of young gold-pheasants, in order to ascertain their sex; for in the males, these feathers are immediately replaced by coloured ones. (36. Mr. Blyth, in Charlesworth's 'Magazine of Natural History,' vol. i. 1837, p. 300. Mr. Bartlett has informed me in regard to gold pheasants.) The actual duration of life is known in but few birds, so that we can hardly judge by this standard. And, with reference to the period at which the power of reproduction is gained, it is a remarkable fact that various birds occasionally breed whilst retaining their immature plumage. (37. I have noticed the following cases in Audubon's 'Ornith. Biography.' The redstart of America (Muscapica ruticilla, vol. i. p. 203). The Ibis tantalus takes four years to come to full maturity, but sometimes breeds in the second year (vol. iii. p. 133). The Grus americanus takes the same time, but breeds before acquiring its full plumage (vol. iii. p. 211). The adults of Ardea caerulea are blue, and the young white; and white, mottled, and mature blue birds may all be seen breeding together (vol. iv. p. 58): but Mr. Blyth informs me that certain herons apparently are dimorphic, for white and coloured individuals of the same age may be observed. The Harlequin duck (Anas histrionica, Linn.) takes three years to acquire its full plumage, though many birds breed in the second year (vol. iii. p. 614). The White-headed Eagle (Falco leucocephalus, vol. iii. p. 210) is likewise known to breed in its immature state. Some species of Oriolus (according to Mr. Blyth and Mr. Swinhoe, in 'Ibis,' July 1863, p. 68) likewise breed before they attain their full plumage.) The fact of birds breeding in their immature plumage seems opposed to the belief that sexual selection has played as important a part, as I believe it has, in giving ornamental colours, plumes, etc., to the males, and, by means of equal transmission, to the females of many species. The objection would be a valid one, if the younger and less ornamented males were as successful in winning females and propagating their kind, as the older and more beautiful males. But we have no reason to suppose that this is the case. Audubon speaks of the breeding of the immature males of Ibis tantalus as a rare event, as does Mr. Swinhoe, in regard to the immature males of Oriolus. (38. See footnote 37 above.) If the young of any species in their immature plumage were more successful in winning partners than the adults, the adult plumage would probably soon be lost, as the males would prevail, which retained their immature dress for the longest period, and thus the character of the species would ultimately be modified. (39. Other animals, belonging to quite distinct classes, are either habitually or occasionally capable of breeding before they have fully acquired their adult characters. This is the case with the young males of the salmon. Several amphibians have been known to breed whilst retaining their larval structure. Fritz Müller has shewn ('Facts and arguments for Darwin,' Eng. trans. 1869, p. 79) that the males of several amphipod crustaceans become sexually mature whilst young; and I infer that this is a case of premature breeding, because they have not as yet acquired their fully-developed claspers. All such facts are highly interesting, as bearing on one means by which species may undergo great modifications of character.) If, on the other hand, the young never succeeded in obtaining a female, the habit of early reproduction would perhaps be sooner or later eliminated, from being superfluous and entailing waste of power. The plumage of certain birds goes on increasing in beauty during many years after they are fully mature; this is the case with the train of the peacock, with some of the birds of paradise, and with the crest and plumes of certain herons, for instance, the Ardea ludovicana. (40. Jerdon, 'Birds of India,' vol. iii. p. 507, on the peacock. Dr. Marshall thinks that the older and more brilliant males of birds of paradise, have an advantage over the younger males; see 'Archives Neerlandaises,' tom. vi. 1871.--On Ardea, Audubon, ibid. vol. iii. p. 139.) But it is doubtful whether the continued development of such feathers is the result of the selection of successive beneficial variations (though this is the most probable view with birds of paradise) or merely of continuous growth. Most fishes continue increasing in size, as long as they are in good health and have plenty of food; and a somewhat similar law may prevail with the plumes of birds. CLASS V. WHEN THE ADULTS OF BOTH SEXES HAVE A DISTINCT WINTER AND SUMMER PLUMAGE, WHETHER OR NOT THE MALE DIFFERS FROM THE FEMALE, THE YOUNG RESEMBLE THE ADULTS OF BOTH SEXES IN THEIR WINTER DRESS, OR MUCH MORE RARELY IN THEIR SUMMER DRESS, OR THEY RESEMBLE THE FEMALES ALONE. OR THE YOUNG MAY HAVE AN INTERMEDIATE CHARACTER; OR, AGAIN, THEY MAY DIFFER GREATLY FROM THE ADULTS IN BOTH THEIR SEASONAL PLUMAGES. The cases in this class are singularly complex; nor is this surprising, as they depend on inheritance, limited in a greater or less degree in three different ways, namely, by sex, age, and the season of the year. In some cases the individuals of the same species pass through at least five distinct states of plumage. With the species, in which the male differs from the female during the summer season alone, or, which is rarer, during both seasons (41. For illustrative cases, see vol. iv. of Macgillivray's 'History of British Birds;' on Tringa, etc., pp. 229, 271; on the Machetes, p. 172; on the Charadrius hiaticula, p. 118; on the Charadrius pluvialis, p. 94.), the young generally resemble the females,--as with the so-called goldfinch of North America, and apparently with the splendid Maluri of Australia. (42. For the goldfinch of N. America, Fringilla tristis, Linn., see Audubon, 'Ornithological Biography,' vol. i. p. 172. For the Maluri, Gould's 'Handbook of the Birds of Australia,' vol. i. p. 318.) With those species, the sexes of which are alike during both the summer and winter, the young may resemble the adults, firstly, in their winter dress; secondly, and this is of much rarer occurrence, in their summer dress; thirdly, they may be intermediate between these two states; and, fourthly, they may differ greatly from the adults at all seasons. We have an instance of the first of these four cases in one of the egrets of India (Buphus coromandus), in which the young and the adults of both sexes are white during the winter, the adults becoming golden-buff during the summer. With the gaper (Anastomus oscitans) of India we have a similar case, but the colours are reversed: for the young and the adults of both sexes are grey and black during the winter, the adults becoming white during the summer. (43. I am indebted to Mr. Blyth for information as to the Buphus; see also Jerdon, 'Birds of India,' vol. iii. p. 749. On the Anastomus, see Blyth, in 'Ibis,' 1867, p. 173.) As an instance of the second case, the young of the razor-bill (Alca torda, Linn.), in an early state of plumage, are coloured like the adults during the summer; and the young of the white-crowned sparrow of North America (Fringilla leucophrys), as soon as fledged, have elegant white stripes on their heads, which are lost by the young and the old during the winter. (44. On the Alca, see Macgillivray, 'Hist. Brit. Birds,' vol. v. p. 347. On the Fringilla leucophrys, Audubon, ibid. vol. ii. p. 89. I shall have hereafter to refer to the young of certain herons and egrets being white.) With respect to the third case, namely, that of the young having an intermediate character between the summer and winter adult plumages, Yarrell (45. 'History of British Birds,' vol. i. 1839, p. 159.) insists that this occurs with many waders. Lastly, in regard to the young differing greatly from both sexes in their adult summer and winter plumages, this occurs with some herons and egrets of North America and India,--the young alone being white. I will make only a few remarks on these complicated cases. When the young resemble the females in their summer dress, or the adults of both sexes in their winter dress, the cases differ from those given under Classes I. and III. only in the characters originally acquired by the males during the breeding-season, having been limited in their transmission to the corresponding season. When the adults have a distinct summer and winter plumage, and the young differ from both, the case is more difficult to understand. We may admit as probable that the young have retained an ancient state of plumage; we can account by sexual selection for the summer or nuptial plumage of the adults, but how are we to account for their distinct winter plumage? If we could admit that this plumage serves in all cases as a protection, its acquirement would be a simple affair; but there seems no good reason for this admission. It may be suggested that the widely different conditions of life during the winter and summer have acted in a direct manner on the plumage; this may have had some effect, but I have not much confidence in so great a difference as we sometimes see between the two plumages, having been thus caused. A more probable explanation is, that an ancient style of plumage, partially modified through the transference of some characters from the summer plumage, has been retained by the adults during the winter. Finally, all the cases in our present class apparently depend on characters acquired by the adult males, having been variously limited in their transmission according to age, season, and sex; but it would not be worth while to attempt to follow out these complex relations. CLASS VI. THE YOUNG IN THEIR FIRST PLUMAGE DIFFER FROM EACH OTHER ACCORDING TO SEX; THE YOUNG MALES RESEMBLING MORE OR LESS CLOSELY THE ADULT MALES, AND THE YOUNG FEMALES MORE OR LESS CLOSELY THE ADULT FEMALES. The cases in the present class, though occurring in various groups, are not numerous; yet it seems the most natural thing that the young should at first somewhat resemble the adults of the same sex, and gradually become more and more like them. The adult male blackcap (Sylvia atricapilla) has a black head, that of the female being reddish-brown; and I am informed by Mr. Blyth, that the young of both sexes can be distinguished by this character even as nestlings. In the family of thrushes an unusual number of similar cases have been noticed; thus, the male blackbird (Turdus merula) can be distinguished in the nest from the female. The two sexes of the mocking bird (Turdus polyglottus, Linn.) differ very little from each other, yet the males can easily be distinguished at a very early age from the females by showing more pure white. (46. Audubon, 'Ornith. Biography,' vol. i. p. 113.) The males of a forest-thrush and of a rock-thrush (Orocetes erythrogastra and Petrocincla cyanea) have much of their plumage of a fine blue, whilst the females are brown; and the nestling males of both species have their main wing and tail-feathers edged with blue whilst those of the female are edged with brown. (47. Mr. C.A. Wright, in 'Ibis,' vol. vi. 1864, p. 65. Jerdon, 'Birds of India,' vol. i. p. 515. See also on the blackbird, Blyth in Charlesworth's 'Magazine of Natural History,' vol. i. 1837, p. 113.) In the young blackbird the wing-feathers assume their mature character and become black after the others; on the other hand, in the two species just named the wing-feathers become blue before the others. The most probable view with reference to the cases in the present class is that the males, differently from what occurs in Class I., have transmitted their colours to their male offspring at an earlier age than that at which they were first acquired; for, if the males had varied whilst quite young, their characters would probably have been transmitted to both sexes. (48. The following additional cases may be mentioned; the young males of Tanagra rubra can be distinguished from the young females (Audubon, 'Ornith. Biography,' vol. iv. p. 392), and so it is within the nestlings of a blue nuthatch, Dendrophila frontalis of India (Jerdon, 'Birds of India,' vol. i. p. 389). Mr. Blyth also informs me that the sexes of the stonechat, Saxicola rubicola, are distinguishable at a very early age. Mr. Salvin gives ('Proc. Zoolog. Soc.' 1870, p. 206) the case of a humming-bird, like the following one of Eustephanus.) In Aithurus polytmus, a humming-bird, the male is splendidly coloured black and green, and two of the tail-feathers are immensely lengthened; the female has an ordinary tail and inconspicuous colours; now the young males, instead of resembling the adult female, in accordance with the common rule, begin from the first to assume the colours proper to their sex, and their tail-feathers soon become elongated. I owe this information to Mr. Gould, who has given me the following more striking and as yet unpublished case. Two humming-birds belonging to the genus Eustephanus, both beautifully coloured, inhabit the small island of Juan Fernandez, and have always been ranked as specifically distinct. But it has lately been ascertained that the one which is of a rich chestnut-brown colour with a golden-red head, is the male, whilst the other which is elegantly variegated with green and white with a metallic green head is the female. Now the young from the first somewhat resemble the adults of the corresponding sex, the resemblance gradually becoming more and more complete. In considering this last case, if as before we take the plumage of the young as our guide, it would appear that both sexes have been rendered beautiful independently; and not that one sex has partially transferred its beauty to the other. The male apparently has acquired his bright colours through sexual selection in the same manner as, for instance, the peacock or pheasant in our first class of cases; and the female in the same manner as the female Rhynchaea or Turnix in our second class of cases. But there is much difficulty in understanding how this could have been effected at the same time with the two sexes of the same species. Mr. Salvin states, as we have seen in the eighth chapter, that with certain humming-birds the males greatly exceed the females in number, whilst with other species inhabiting the same country the females greatly exceed the males. If, then, we might assume that during some former lengthened period the males of the Juan Fernandez species had greatly exceeded the females in number, but that during another lengthened period the females had far exceeded the males, we could understand how the males at one time, and the females at another, might have been rendered beautiful by the selection of the brighter coloured individuals of either sex; both sexes transmitting their characters to their young at a rather earlier age than usual. Whether this is the true explanation I will not pretend to say; but the case is too remarkable to be passed over without notice. We have now seen in all six classes, that an intimate relation exists between the plumage of the young and the adults, either of one sex or both. These relations are fairly well explained on the principle that one sex--this being in the great majority of cases the male--first acquired through variation and sexual selection bright colours or other ornaments, and transmitted them in various ways, in accordance with the recognised laws of inheritance. Why variations have occurred at different periods of life, even sometimes with species of the same group, we do not know, but with respect to the form of transmission, one important determining cause seems to be the age at which the variations first appear. From the principle of inheritance at corresponding ages, and from any variations in colour which occurred in the males at an early age not being then selected--on the contrary being often eliminated as dangerous--whilst similar variations occurring at or near the period of reproduction have been preserved, it follows that the plumage of the young will often have been left unmodified, or but little modified. We thus get some insight into the colouring of the progenitors of our existing species. In a vast number of species in five out of our six classes of cases, the adults of one sex or of both are bright coloured, at least during the breeding-season, whilst the young are invariably less brightly coloured than the adults, or are quite dull coloured; for no instance is known, as far as I can discover, of the young of dull-coloured species displaying bright colours, or of the young of bright-coloured species being more brilliant than their parents. In the fourth class, however, in which the young and the old resemble each other, there are many species (though by no means all), of which the young are bright-coloured, and as these form old groups, we may infer that their early progenitors were likewise bright. With this exception, if we look to the birds of the world, it appears that their beauty has been much increased since that period, of which their immature plumage gives us a partial record. ON THE COLOUR OF THE PLUMAGE IN RELATION TO PROTECTION. It will have been seen that I cannot follow Mr. Wallace in the belief that dull colours, when confined to the females, have been in most cases specially gained for the sake of protection. There can, however, be no doubt, as formerly remarked, that both sexes of many birds have had their colours modified, so as to escape the notice of their enemies; or in some instances, so as to approach their prey unobserved, just as owls have had their plumage rendered soft, that their flight may not be overheard. Mr. Wallace remarks (49. 'Westminster Review,' July 1867, p. 5.) that "it is only in the tropics, among forests which never lose their foliage, that we find whole groups of birds, whose chief colour is green." It will be admitted by every one, who has ever tried, how difficult it is to distinguish parrots in a leaf-covered tree. Nevertheless, we must remember that many parrots are ornamented with crimson, blue, and orange tints, which can hardly be protective. Woodpeckers are eminently arboreal, but besides green species, there are many black, and black-and-white kinds--all the species being apparently exposed to nearly the same dangers. It is therefore probable that with tree-haunting birds, strongly-pronounced colours have been acquired through sexual selection, but that a green tint has been acquired oftener than any other, from the additional advantage of protection. In regard to birds which live on the ground, every one admits that they are coloured so as to imitate the surrounding surface. How difficult it is to see a partridge, snipe, woodcock, certain plovers, larks, and night-jars when crouched on ground. Animals inhabiting deserts offer the most striking cases, for the bare surface affords no concealment, and nearly all the smaller quadrupeds, reptiles, and birds depend for safety on their colours. Mr. Tristram has remarked in regard to the inhabitants of the Sahara, that all are protected by their "isabelline or sand-colour." (50. 'Ibis,' 1859, vol. i. p. 429, et seq. Dr. Rohlfs, however, remarks to me in a letter that according to his experience of the Sahara, this statement is too strong.) Calling to my recollection the desert-birds of South America, as well as most of the ground-birds of Great Britain, it appeared to me that both sexes in such cases are generally coloured nearly alike. Accordingly, I applied to Mr. Tristram with respect to the birds of the Sahara, and he has kindly given me the following information. There are twenty-six species belonging to fifteen genera, which manifestly have their plumage coloured in a protective manner; and this colouring is all the more striking, as with most of these birds it differs from that of their congeners. Both sexes of thirteen out of the twenty-six species are coloured in the same manner; but these belong to genera in which this rule commonly prevails, so that they tell us nothing about the protective colours being the same in both sexes of desert-birds. Of the other thirteen species, three belong to genera in which the sexes usually differ from each other, yet here they have the sexes alike. In the remaining ten species, the male differs from the female; but the difference is confined chiefly to the under surface of the plumage, which is concealed when the bird crouches on the ground; the head and back being of the same sand-coloured hue in the two sexes. So that in these ten species the upper surfaces of both sexes have been acted on and rendered alike, through natural selection, for the sake of protection; whilst the lower surfaces of the males alone have been diversified, through sexual selection, for the sake of ornament. Here, as both sexes are equally well protected, we clearly see that the females have not been prevented by natural selection from inheriting the colours of their male parents; so that we must look to the law of sexually-limited transmission. In all parts of the world both sexes of many soft-billed birds, especially those which frequent reeds or sedges, are obscurely coloured. No doubt if their colours had been brilliant, they would have been much more conspicuous to their enemies; but whether their dull tints have been specially gained for the sake of protection seems, as far as I can judge, rather doubtful. It is still more doubtful whether such dull tints can have been gained for the sake of ornament. We must, however, bear in mind that male birds, though dull-coloured, often differ much from their females (as with the common sparrow), and this leads to the belief that such colours have been gained through sexual selection, from being attractive. Many of the soft-billed birds are songsters; and a discussion in a former chapter should not be forgotten, in which it was shewn that the best songsters are rarely ornamented with bright tints. It would appear that female birds, as a general rule, have selected their mates either for their sweet voices or gay colours, but not for both charms combined. Some species, which are manifestly coloured for the sake of protection, such as the jack-snipe, woodcock, and night-jar, are likewise marked and shaded, according to our standard of taste, with extreme elegance. In such cases we may conclude that both natural and sexual selection have acted conjointly for protection and ornament. Whether any bird exists which does not possess some special attraction, by which to charm the opposite sex, may be doubted. When both sexes are so obscurely coloured that it would be rash to assume the agency of sexual selection, and when no direct evidence can be advanced shewing that such colours serve as a protection, it is best to own complete ignorance of the cause, or, which comes to nearly the same thing, to attribute the result to the direct action of the conditions of life. Both sexes of many birds are conspicuously, though not brilliantly coloured, such as the numerous black, white, or piebald species; and these colours are probably the result of sexual selection. With the common blackbird, capercailzie, blackcock, black scoter-duck (Oidemia), and even with one of the birds of paradise (Lophorina atra), the males alone are black, whilst the females are brown or mottled; and there can hardly be a doubt that blackness in these cases has been a sexually selected character. Therefore it is in some degree probable that the complete or partial blackness of both sexes in such birds as crows, certain cockatoos, storks, and swans, and many marine birds, is likewise the result of sexual selection, accompanied by equal transmission to both sexes; for blackness can hardly serve in any case as a protection. With several birds, in which the male alone is black, and in others in which both sexes are black, the beak or skin about the head is brightly coloured, and the contrast thus afforded adds much to their beauty; we see this in the bright yellow beak of the male blackbird, in the crimson skin over the eyes of the blackcock and capercailzie, in the brightly and variously coloured beak of the scoter-drake (Oidemia), in the red beak of the chough (Corvus graculus, Linn.), of the black swan, and the black stork. This leads me to remark that it is not incredible that toucans may owe the enormous size of their beaks to sexual selection, for the sake of displaying the diversified and vivid stripes of colour, with which these organs are ornamented. (51. No satisfactory explanation has ever been offered of the immense size, and still less of the bright colours, of the toucan's beak. Mr. Bates ('The Naturalist on the Amazons,' vol. ii. 1863, p. 341) states that they use their beaks for reaching fruit at the extreme tips of the branches; and likewise, as stated by other authors, for extracting eggs and young birds from the nests of other birds. But, as Mr. Bates admits, the beak "can scarcely be considered a very perfectly-formed instrument for the end to which it is applied." The great bulk of the beak, as shewn by its breadth, depth, as well as length, is not intelligible on the view, that it serves merely as an organ of prehension. Mr. Belt believes ('The Naturalist in Nicaragua,' p. 197) that the principal use of the beak is as a defence against enemies, especially to the female whilst nesting in a hole in a tree.) The naked skin, also, at the base of the beak and round the eyes is likewise often brilliantly coloured; and Mr. Gould, in speaking of one species (52. Rhamphastos carinatus, Gould's 'Monograph of Ramphastidae.'), says that the colours of the beak "are doubtless in the finest and most brilliant state during the time of pairing." There is no greater improbability that toucans should be encumbered with immense beaks, though rendered as light as possible by their cancellated structure, for the display of fine colours (an object falsely appearing to us unimportant), than that the male Argus pheasant and some other birds should be encumbered with plumes so long as to impede their flight. In the same manner, as the males alone of various species are black, the females being dull-coloured; so in a few cases the males alone are either wholly or partially white, as with the several bell-birds of South America (Chasmorhynchus), the Antarctic goose (Bernicla antarctica), the silver pheasant, etc., whilst the females are brown or obscurely mottled. Therefore, on the same principle as before, it is probable that both sexes of many birds, such as white cockatoos, several egrets with their beautiful plumes, certain ibises, gulls, terns, etc., have acquired their more or less completely white plumage through sexual selection. In some of these cases the plumage becomes white only at maturity. This is the case with certain gannets, tropic-birds, etc., and with the snow-goose (Anser hyperboreus). As the latter breeds on the "barren grounds," when not covered with snow, and as it migrates southward during the winter, there is no reason to suppose that its snow-white adult plumage serves as a protection. In the Anastomus oscitans, we have still better evidence that the white plumage is a nuptial character, for it is developed only during the summer; the young in their immature state, and the adults in their winter dress, being grey and black. With many kinds of gulls (Larus), the head and neck become pure white during the summer, being grey or mottled during the winter and in the young state. On the other hand, with the smaller gulls, or sea-mews (Gavia), and with some terns (Sterna), exactly the reverse occurs; for the heads of the young birds during the first year, and of the adults during the winter, are either pure white, or much paler coloured than during the breeding-season. These latter cases offer another instance of the capricious manner in which sexual selection appears often to have acted. (53. On Larus, Gavia, and Sterna, see Macgillivray, 'History of British Birds,' vol. v. pp. 515, 584, 626. On the Anser hyperboreus, Audubon, 'Ornithological Biography,' vol. iv. p. 562. On the Anastomus, Mr. Blyth, in 'Ibis,' 1867, p. 173.) That aquatic birds have acquired a white plumage so much oftener than terrestrial birds, probably depends on their large size and strong powers of flight, so that they can easily defend themselves or escape from birds of prey, to which moreover they are not much exposed. Consequently, sexual selection has not here been interfered with or guided for the sake of protection. No doubt with birds which roam over the open ocean, the males and females could find each other much more easily, when made conspicuous either by being perfectly white or intensely black; so that these colours may possibly serve the same end as the call-notes of many land-birds. (54. It may be noticed that with vultures, which roam far and wide high in the air, like marine birds over the ocean, three or four species are almost wholly or largely white, and that many others are black. So that here again conspicuous colours may possibly aid the sexes in finding each other during the breeding-season.) A white or black bird when it discovers and flies down to a carcase floating on the sea or cast up on the beach, will be seen from a great distance, and will guide other birds of the same and other species, to the prey; but as this would be a disadvantage to the first finders, the individuals which were the whitest or blackest would not thus procure more food than the less strongly coloured individuals. Hence conspicuous colours cannot have been gradually acquired for this purpose through natural selection. As sexual selection depends on so fluctuating an element as taste, we can understand how it is that, within the same group of birds having nearly the same habits, there should exist white or nearly white, as well as black, or nearly black species,--for instance, both white and black cockatoos, storks, ibises, swans, terns, and petrels. Piebald birds likewise sometimes occur in the same groups together with black and white species; for instance, the black-necked swan, certain terns, and the common magpie. That a strong contrast in colour is agreeable to birds, we may conclude by looking through any large collection, for the sexes often differ from each other in the male having the pale parts of a purer white, and the variously coloured dark parts of still darker tints than the female. It would even appear that mere novelty, or slight changes for the sake of change, have sometimes acted on female birds as a charm, like changes of fashion with us. Thus the males of some parrots can hardly be said to be more beautiful than the females, at least according to our taste, but they differ in such points, as in having a rose-coloured collar instead of "a bright emeraldine narrow green collar"; or in the male having a black collar instead of "a yellow demi-collar in front," with a pale roseate instead of a plum-blue head. (55. See Jerdon on the genus Palaeornis, 'Birds of India,' vol. i. pp. 258-260.) As so many male birds have elongated tail-feathers or elongated crests for their chief ornament, the shortened tail, formerly described in the male of a humming-bird, and the shortened crest of the male goosander, seem like one of the many changes of fashion which we admire in our own dresses. Some members of the heron family offer a still more curious case of novelty in colouring having, as it appears, been appreciated for the sake of novelty. The young of the Ardea asha are white, the adults being dark slate-coloured; and not only the young, but the adults in their winter plumage, of the allied Buphus coromandus are white, this colour changing into a rich golden-buff during the breeding-season. It is incredible that the young of these two species, as well as of some other members of the same family (56. The young of Ardea rufescens and A. caerulea of the United States are likewise white, the adults being coloured in accordance with their specific names. Audubon ('Ornithological Biography,' vol. iii. p. 416; vol. iv. p. 58) seems rather pleased at the thought that this remarkable change of plumage will greatly "disconcert the systematists."), should for any special purpose have been rendered pure white and thus made conspicuous to their enemies; or that the adults of one of these two species should have been specially rendered white during the winter in a country which is never covered with snow. On the other hand we have good reason to believe that whiteness has been gained by many birds as a sexual ornament. We may therefore conclude that some early progenitor of the Ardea asha and the Buphus acquired a white plumage for nuptial purposes, and transmitted this colour to their young; so that the young and the old became white like certain existing egrets; and that the whiteness was afterwards retained by the young, whilst it was exchanged by the adults for more strongly-pronounced tints. But if we could look still further back to the still earlier progenitors of these two species, we should probably see the adults dark-coloured. I infer that this would be the case, from the analogy of many other birds, which are dark whilst young, and when adult are white; and more especially from the case of the Ardea gularis, the colours of which are the reverse of those of A. asha, for the young are dark-coloured and the adults white, the young having retained a former state of plumage. It appears therefore that, during a long line of descent, the adult progenitors of the Ardea asha, the Buphus, and of some allies, have undergone the following changes of colour: first, a dark shade; secondly, pure white; and thirdly, owing to another change of fashion (if I may so express myself), their present slaty, reddish, or golden-buff tints. These successive changes are intelligible only on the principle of novelty having been admired by birds for its own sake. Several writers have objected to the whole theory of sexual selection, by assuming that with animals and savages the taste of the female for certain colours or other ornaments would not remain constant for many generations; that first one colour and then another would be admired, and consequently that no permanent effect could be produced. We may admit that taste is fluctuating, but it is not quite arbitrary. It depends much on habit, as we see in mankind; and we may infer that this would hold good with birds and other animals. Even in our own dress, the general character lasts long, and the changes are to a certain extent graduated. Abundant evidence will be given in two places in a future chapter, that savages of many races have admired for many generations the same cicatrices on the skin, the same hideously perforated lips, nostrils, or ears, distorted heads, etc.; and these deformities present some analogy to the natural ornaments of various animals. Nevertheless, with savages such fashions do not endure for ever, as we may infer from the differences in this respect between allied tribes on the same continent. So again the raisers of fancy animals certainly have admired for many generations and still admire the same breeds; they earnestly desire slight changes, which are considered as improvements, but any great or sudden change is looked at as the greatest blemish. With birds in a state of nature we have no reason to suppose that they would admire an entirely new style of coloration, even if great and sudden variations often occurred, which is far from being the case. We know that dovecot pigeons do not willingly associate with the variously coloured fancy breeds; that albino birds do not commonly get partners in marriage; and that the black ravens of the Feroe Islands chase away their piebald brethren. But this dislike of a sudden change would not preclude their appreciating slight changes, any more than it does in the case of man. Hence with respect to taste, which depends on many elements, but partly on habit and partly on a love of novelty, there seems no improbability in animals admiring for a very long period the same general style of ornamentation or other attractions, and yet appreciating slight changes in colours, form, or sound. SUMMARY OF THE FOUR CHAPTERS ON BIRDS. Most male birds are highly pugnacious during the breeding-season, and some possess weapons adapted for fighting with their rivals. But the most pugnacious and the best armed males rarely or never depend for success solely on their power to drive away or kill their rivals, but have special means for charming the female. With some it is the power of song, or of giving forth strange cries, or instrumental music, and the males in consequence differ from the females in their vocal organs, or in the structure of certain feathers. From the curiously diversified means for producing various sounds, we gain a high idea of the importance of this means of courtship. Many birds endeavour to charm the females by love-dances or antics, performed on the ground or in the air, and sometimes at prepared places. But ornaments of many kinds, the most brilliant tints, combs and wattles, beautiful plumes, elongated feathers, top-knots, and so forth, are by far the commonest means. In some cases mere novelty appears to have acted as a charm. The ornaments of the males must be highly important to them, for they have been acquired in not a few cases at the cost of increased danger from enemies, and even at some loss of power in fighting with their rivals. The males of very many species do not assume their ornamental dress until they arrive at maturity, or they assume it only during the breeding-season, or the tints then become more vivid. Certain ornamental appendages become enlarged, turgid, and brightly coloured during the act of courtship. The males display their charms with elaborate care and to the best effect; and this is done in the presence of the females. The courtship is sometimes a prolonged affair, and many males and females congregate at an appointed place. To suppose that the females do not appreciate the beauty of the males, is to admit that their splendid decorations, all their pomp and display, are useless; and this is incredible. Birds have fine powers of discrimination, and in some few instances it can be shewn that they have a taste for the beautiful. The females, moreover, are known occasionally to exhibit a marked preference or antipathy for certain individual males. If it be admitted that the females prefer, or are unconsciously excited by the more beautiful males, then the males would slowly but surely be rendered more and more attractive through sexual selection. That it is this sex which has been chiefly modified, we may infer from the fact that, in almost every genus where the sexes differ, the males differ much more from one another than do the females; this is well shewn in certain closely-allied representative species, in which the females can hardly be distinguished, whilst the males are quite distinct. Birds in a state of nature offer individual differences which would amply suffice for the work of sexual selection; but we have seen that they occasionally present more strongly marked variations which recur so frequently that they would immediately be fixed, if they served to allure the female. The laws of variation must determine the nature of the initial changes, and will have largely influenced the final result. The gradations, which may be observed between the males of allied species, indicate the nature of the steps through which they have passed. They explain also in the most interesting manner how certain characters have originated, such as the indented ocelli on the tail-feathers of the peacock, and the ball-and-socket ocelli on the wing-feathers of the Argus pheasant. It is evident that the brilliant colours, top-knots, fine plumes, etc., of many male birds cannot have been acquired as a protection; indeed, they sometimes lead to danger. That they are not due to the direct and definite action of the conditions of life, we may feel assured, because the females have been exposed to the same conditions, and yet often differ from the males to an extreme degree. Although it is probable that changed conditions acting during a lengthened period have in some cases produced a definite effect on both sexes, or sometimes on one sex alone, the more important result will have been an increased tendency to vary or to present more strongly-marked individual differences; and such differences will have afforded an excellent ground-work for the action of sexual selection. The laws of inheritance, irrespectively of selection, appear to have determined whether the characters acquired by the males for the sake of ornament, for producing various sounds, and for fighting together, have been transmitted to the males alone or to both sexes, either permanently, or periodically during certain seasons of the year. Why various characters should have been transmitted sometimes in one way and sometimes in another, is not in most cases known; but the period of variability seems often to have been the determining cause. When the two sexes have inherited all characters in common they necessarily resemble each other; but as the successive variations may be differently transmitted, every possible gradation may be found, even within the same genus, from the closest similarity to the widest dissimilarity between the sexes. With many closely-allied species, following nearly the same habits of life, the males have come to differ from each other chiefly through the action of sexual selection; whilst the females have come to differ chiefly from partaking more or less of the characters thus acquired by the males. The effects, moreover, of the definite action of the conditions of life, will not have been masked in the females, as in the males, by the accumulation through sexual selection of strongly-pronounced colours and other ornaments. The individuals of both sexes, however affected, will have been kept at each successive period nearly uniform by the free intercrossing of many individuals. With species, in which the sexes differ in colour, it is possible or probable that some of the successive variations often tended to be transmitted equally to both sexes; but that when this occurred the females were prevented from acquiring the bright colours of the males, by the destruction which they suffered during incubation. There is no evidence that it is possible by natural selection to convert one form of transmission into another. But there would not be the least difficulty in rendering a female dull-coloured, the male being still kept bright-coloured, by the selection of successive variations, which were from the first limited in their transmission to the same sex. Whether the females of many species have actually been thus modified, must at present remain doubtful. When, through the law of the equal transmission of characters to both sexes, the females were rendered as conspicuously coloured as the males, their instincts appear often to have been modified so that they were led to build domed or concealed nests. In one small and curious class of cases the characters and habits of the two sexes have been completely transposed, for the females are larger, stronger, more vociferous and brighter coloured than the males. They have, also, become so quarrelsome that they often fight together for the possession of the males, like the males of other pugnacious species for the possession of the females. If, as seems probable, such females habitually drive away their rivals, and by the display of their bright colours or other charms endeavour to attract the males, we can understand how it is that they have gradually been rendered, by sexual selection and sexually-limited transmission, more beautiful than the males--the latter being left unmodified or only slightly modified. Whenever the law of inheritance at corresponding ages prevails but not that of sexually-limited transmission, then if the parents vary late in life--and we know that this constantly occurs with our poultry, and occasionally with other birds--the young will be left unaffected, whilst the adults of both sexes will be modified. If both these laws of inheritance prevail and either sex varies late in life, that sex alone will be modified, the other sex and the young being unaffected. When variations in brightness or in other conspicuous characters occur early in life, as no doubt often happens, they will not be acted on through sexual selection until the period of reproduction arrives; consequently if dangerous to the young, they will be eliminated through natural selection. Thus we can understand how it is that variations arising late in life have so often been preserved for the ornamentation of the males; the females and the young being left almost unaffected, and therefore like each other. With species having a distinct summer and winter plumage, the males of which either resemble or differ from the females during both seasons or during the summer alone, the degrees and kinds of resemblance between the young and the old are exceedingly complex; and this complexity apparently depends on characters, first acquired by the males, being transmitted in various ways and degrees, as limited by age, sex, and season. As the young of so many species have been but little modified in colour and in other ornaments, we are enabled to form some judgment with respect to the plumage of their early progenitors; and we may infer that the beauty of our existing species, if we look to the whole class, has been largely increased since that period, of which the immature plumage gives us an indirect record. Many birds, especially those which live much on the ground, have undoubtedly been obscurely coloured for the sake of protection. In some instances the upper exposed surface of the plumage has been thus coloured in both sexes, whilst the lower surface in the males alone has been variously ornamented through sexual selection. Finally, from the facts given in these four chapters, we may conclude that weapons for battle, organs for producing sound, ornaments of many kinds, bright and conspicuous colours, have generally been acquired by the males through variation and sexual selection, and have been transmitted in various ways according to the several laws of inheritance--the females and the young being left comparatively but little modified. (57. I am greatly indebted to the kindness of Mr. Sclater for having looked over these four chapters on birds, and the two following ones on mammals. In this way I have been saved from making mistakes about the names of the species, and from stating anything as a fact which is known to this distinguished naturalist to be erroneous. But, of course, he is not at all answerable for the accuracy of the statements quoted by me from various authorities.) CHAPTER XVII. SECONDARY SEXUAL CHARACTERS OF MAMMALS. The law of battle--Special weapons, confined to the males--Cause of absence of weapons in the female--Weapons common to both sexes, yet primarily acquired by the male--Other uses of such weapons--Their high importance--Greater size of the male--Means of defence--On the preference shown by either sex in the pairing of quadrupeds. With mammals the male appears to win the female much more through the law of battle than through the display of his charms. The most timid animals, not provided with any special weapons for fighting, engage in desperate conflicts during the season of love. Two male hares have been seen to fight together until one was killed; male moles often fight, and sometimes with fatal results; male squirrels engage in frequent contests, "and often wound each other severely"; as do male beavers, so that "hardly a skin is without scars." (1. See Waterton's account of two hares fighting, 'Zoologist,' vol. i. 1843, p. 211. On moles, Bell, 'Hist. of British Quadrupeds,' 1st ed., p. 100. On squirrels, Audubon and Bachman, Viviparous Quadrupeds of N. America, 1846, p. 269. On beavers, Mr. A.H. Green, in 'Journal of Linnean Society, Zoology,' vol. x. 1869, p. 362.) I observed the same fact with the hides of the guanacoes in Patagonia; and on one occasion several were so absorbed in fighting that they fearlessly rushed close by me. Livingstone speaks of the males of the many animals in Southern Africa as almost invariably shewing the scars received in former contests. The law of battle prevails with aquatic as with terrestrial mammals. It is notorious how desperately male seals fight, both with their teeth and claws, during the breeding-season; and their hides are likewise often covered with scars. Male sperm-whales are very jealous at this season; and in their battles "they often lock their jaws together, and turn on their sides and twist about"; so that their lower jaws often become distorted. (2. On the battles of seals, see Capt. C. Abbott in 'Proc. Zool. Soc.' 1868, p. 191; Mr. R. Brown, ibid. 1868, p. 436; also L. Lloyd, 'Game Birds of Sweden,' 1867, p. 412; also Pennant. On the sperm-whale see Mr. J.H. Thompson, in 'Proc. Zool. Soc.' 1867, p. 246.) All male animals which are furnished with special weapons for fighting, are well known to engage in fierce battles. The courage and the desperate conflicts of stags have often been described; their skeletons have been found in various parts of the world, with the horns inextricably locked together, shewing how miserably the victor and vanquished had perished. (3. See Scrope ('Art of Deer-stalking,' p. 17) on the locking of the horns with the Cervus elaphus. Richardson, in 'Fauna Bor. Americana,' 1829, p. 252, says that the wapiti, moose, and reindeer have been found thus locked together. Sir A. Smith found at the Cape of Good Hope the skeletons of two gnus in the same condition.) No animal in the world is so dangerous as an elephant in must. Lord Tankerville has given me a graphic description of the battles between the wild bulls in Chillingham Park, the descendants, degenerated in size but not in courage, of the gigantic Bos primigenius. In 1861 several contended for mastery; and it was observed that two of the younger bulls attacked in concert the old leader of the herd, overthrew and disabled him, so that he was believed by the keepers to be lying mortally wounded in a neighbouring wood. But a few days afterwards one of the young bulls approached the wood alone; and then the "monarch of the chase," who had been lashing himself up for vengeance, came out and, in a short time, killed his antagonist. He then quietly joined the herd, and long held undisputed sway. Admiral Sir B.J. Sulivan informs me that, when he lived in the Falkland Islands, he imported a young English stallion, which frequented the hills near Port William with eight mares. On these hills there were two wild stallions, each with a small troop of mares; "and it is certain that these stallions would never have approached each other without fighting. Both had tried singly to fight the English horse and drive away his mares, but had failed. One day they came in TOGETHER and attacked him. This was seen by the capitan who had charge of the horses, and who, on riding to the spot, found one of the two stallions engaged with the English horse, whilst the other was driving away the mares, and had already separated four from the rest. The capitan settled the matter by driving the whole party into the corral, for the wild stallions would not leave the mares." Male animals which are provided with efficient cutting or tearing teeth for the ordinary purposes of life, such as the carnivora, insectivora, and rodents, are seldom furnished with weapons especially adapted for fighting with their rivals. The case is very different with the males of many other animals. We see this in the horns of stags and of certain kinds of antelopes in which the females are hornless. With many animals the canine teeth in the upper or lower jaw, or in both, are much larger in the males than in the females, or are absent in the latter, with the exception sometimes of a hidden rudiment. Certain antelopes, the musk-deer, camel, horse, boar, various apes, seals, and the walrus, offer instances. In the females of the walrus the tusks are sometimes quite absent. (4. Mr. Lamont ('Seasons with the Sea-Horses,' 1861, p. 143) says that a good tusk of the male walrus weighs 4 pounds, and is longer than that of the female, which weighs about 3 pounds. The males are described as fighting ferociously. On the occasional absence of the tusks in the female, see Mr. R. Brown, 'Proceedings, Zoological Society,' 1868, p. 429.) In the male elephant of India and in the male dugong (5. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 283.) the upper incisors form offensive weapons. In the male narwhal the left canine alone is developed into the well-known, spirally-twisted, so-called horn, which is sometimes from nine to ten feet in length. It is believed that the males use these horns for fighting together; for "an unbroken one can rarely be got, and occasionally one may be found with the point of another jammed into the broken place." (6. Mr. R. Brown, in 'Proc. Zool. Soc.' 1869, p. 553. See Prof. Turner, in 'Journal of Anat. and Phys.' 1872, p. 76, on the homological nature of these tusks. Also Mr. J.W. Clarke on two tusks being developed in the males, in 'Proceedings of the Zoological Society,' 1871, p. 42.) The tooth on the opposite side of the head in the male consists of a rudiment about ten inches in length, which is embedded in the jaw; but sometimes, though rarely, both are equally developed on the two sides. In the female both are always rudimentary. The male cachalot has a larger head than that of the female, and it no doubt aids him in his aquatic battles. Lastly, the adult male ornithorhynchus is provided with a remarkable apparatus, namely a spur on the foreleg, closely resembling the poison-fang of a venomous snake; but according to Harting, the secretion from the gland is not poisonous; and on the leg of the female there is a hollow, apparently for the reception of the spur. (7. Owen on the cachalot and Ornithorhynchus, ibid. vol. iii. pp. 638, 641. Harting is quoted by Dr. Zouteveen in the Dutch translation of this work, vol. ii. p. 292.) When the males are provided with weapons which in the females are absent, there can be hardly a doubt that these serve for fighting with other males; and that they were acquired through sexual selection, and were transmitted to the male sex alone. It is not probable, at least in most cases, that the females have been prevented from acquiring such weapons, on account of their being useless, superfluous, or in some way injurious. On the contrary, as they are often used by the males for various purposes, more especially as a defence against their enemies, it is a surprising fact that they are so poorly developed, or quite absent, in the females of so many animals. With female deer the development during each recurrent season of great branching horns, and with female elephants the development of immense tusks, would be a great waste of vital power, supposing that they were of no use to the females. Consequently, they would have tended to be eliminated in the female through natural selection; that is, if the successive variations were limited in their transmission to the female sex, for otherwise the weapons of the males would have been injuriously affected, and this would have been a greater evil. On the whole, and from the consideration of the following facts, it seems probable that when the various weapons differ in the two sexes, this has generally depended on the kind of transmission which has prevailed. As the reindeer is the one species in the whole family of Deer, in which the female is furnished with horns, though they are somewhat smaller, thinner, and less branched than in the male, it might naturally be thought that, at least in this case, they must be of some special service to her. The female retains her horns from the time when they are fully developed, namely, in September, throughout the winter until April or May, when she brings forth her young. Mr. Crotch made particular enquiries for me in Norway, and it appears that the females at this season conceal themselves for about a fortnight in order to bring forth their young, and then reappear, generally hornless. In Nova Scotia, however, as I hear from Mr. H. Reeks, the female sometimes retains her horns longer. The male on the other hand casts his horns much earlier, towards the end of November. As both sexes have the same requirements and follow the same habits of life, and as the male is destitute of horns during the winter, it is improbable that they can be of any special service to the female during this season, which includes the larger part of the time during which she is horned. Nor is it probable that she can have inherited horns from some ancient progenitor of the family of deer, for, from the fact of the females of so many species in all quarters of the globe not having horns, we may conclude that this was the primordial character of the group. (8. On the structure and shedding of the horns of the reindeer, Hoffberg, 'Amoenitates Acad.' vol. iv. 1788, p. 149. See Richardson, 'Fauna Bor. Americana,' p. 241, in regard to the American variety or species: also Major W. Ross King, 'The Sportsman in Canada,' 1866, p. 80. The horns of the reindeer are developed at a most unusually early age; but what the cause of this may be is not known. The effect has apparently been the transference of the horns to both sexes. We should bear in mind that horns are always transmitted through the female, and that she has a latent capacity for their development, as we see in old or diseased females. (9. Isidore Geoffroy St.-Hilaire, 'Essais de Zoolog. Générale,' 1841, p. 513. Other masculine characters, besides the horns, are sometimes similarly transferred to the female; thus Mr. Boner, in speaking of an old female chamois ('Chamois Hunting in the Mountains of Bavaria,' 1860, 2nd ed., p. 363), says, "not only was the head very male-looking, but along the back there was a ridge of long hair, usually to be found only in bucks.") Moreover the females of some other species of deer exhibit, either normally or occasionally, rudiments of horns; thus the female of Cervulus moschatus has "bristly tufts, ending in a knob, instead of a horn"; and "in most specimens of the female wapiti (Cervus canadensis) there is a sharp bony protuberance in the place of the horn." (10. On the Cervulus, Dr. Gray, 'Catalogue of Mammalia in the British Museum,' part iii. p. 220. On the Cervus canadensis or wapiti, see Hon. J.D. Caton, 'Ottawa Academy of Nat. Sciences,' May 1868, p. 9.) From these several considerations we may conclude that the possession of fairly well-developed horns by the female reindeer, is due to the males having first acquired them as weapons for fighting with other males; and secondarily to their development from some unknown cause at an unusually early age in the males, and their consequent transference to both sexes. Turning to the sheath-horned ruminants: with antelopes a graduated series can be formed, beginning with species, the females of which are completely destitute of horns--passing on to those which have horns so small as to be almost rudimentary (as with the Antilocapra americana, in which species they are present in only one out of four or five females (11. I am indebted to Dr. Canfield for this information; see also his paper in the 'Proceedings of the Zoological Society,' 1866, p. 105.))--to those which have fairly developed horns, but manifestly smaller and thinner than in the male and sometimes of a different shape (12. For instance the horns of the female Ant. euchore resemble those of a distinct species, viz. the Ant. dorcas var. Corine, see Desmarest, 'Mammalogie,' p. 455.),--and ending with those in which both sexes have horns of equal size. As with the reindeer, so with antelopes, there exists, as previously shewn, a relation between the period of the development of the horns and their transmission to one or both sexes; it is therefore probable that their presence or absence in the females of some species, and their more or less perfect condition in the females of other species, depends, not on their being of any special use, but simply on inheritance. It accords with this view that even in the same restricted genus both sexes of some species, and the males alone of others, are thus provided. It is also a remarkable fact that, although the females of Antilope bezoartica are normally destitute of horns, Mr. Blyth has seen no less than three females thus furnished; and there was no reason to suppose that they were old or diseased. In all the wild species of goats and sheep the horns are larger in the male than in the female, and are sometimes quite absent in the latter. (13. Gray, 'Catalogue of Mammalia, the British Museum,' part iii. 1852, p. 160.) In several domestic breeds of these two animals, the males alone are furnished with horns; and in some breeds, for instance, in the sheep of North Wales, though both sexes are properly horned, the ewes are very liable to be hornless. I have been informed by a trustworthy witness, who purposely inspected a flock of these same sheep during the lambing season, that the horns at birth are generally more fully developed in the male than in the female. Mr. J. Peel crossed his Lonk sheep, both sexes of which always bear horns, with hornless Leicesters and hornless Shropshire Downs; and the result was that the male offspring had their horns considerably reduced, whilst the females were wholly destitute of them. These several facts indicate that, with sheep, the horns are a much less firmly fixed character in the females than in the males; and this leads us to look at the horns as properly of masculine origin. With the adult musk-ox (Ovibos moschatus) the horns of the male are larger than those of the female, and in the latter the bases do not touch. (14. Richardson, 'Fauna Bor. Americana,' p. 278.) In regard to ordinary cattle Mr. Blyth remarks: "In most of the wild bovine animals the horns are both longer and thicker in the bull than in the cow, and in the cow-banteng (Bos sondaicus) the horns are remarkably small, and inclined much backwards. In the domestic races of cattle, both of the humped and humpless types, the horns are short and thick in the bull, longer and more slender in the cow and ox; and in the Indian buffalo, they are shorter and thicker in the bull, longer and more slender in the cow. In the wild gaour (B. gaurus) the horns are mostly both longer and thicker in the bull than in the cow." (15. 'Land and Water,' 1867, p. 346.) Dr. Forsyth Major also informs me that a fossil skull, believed to be that of the female Bos etruscus, has been found in Val d'Arno, which is wholly without horns. In the Rhinoceros simus, as I may add, the horns of the female are generally longer but less powerful than in the male; and in some other species of rhinoceros they are said to be shorter in the female. (16. Sir Andrew Smith, 'Zoology of S. Africa,' pl. xix. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 624.) From these various facts we may infer as probable that horns of all kinds, even when they are equally developed in the two sexes, were primarily acquired by the male in order to conquer other males, and have been transferred more or less completely to the female. The effects of castration deserve notice, as throwing light on this same point. Stags after the operation never renew their horns. The male reindeer, however, must be excepted, as after castration he does renew them. This fact, as well as the possession of horns by both sexes, seems at first to prove that the horns in this species do not constitute a sexual character (17. This is the conclusion of Seidlitz, 'Die Darwinsche Theorie,' 1871, p. 47.); but as they are developed at a very early age, before the sexes differ in constitution, it is not surprising that they should be unaffected by castration, even if they were aboriginally acquired by the male. With sheep both sexes properly bear horns; and I am informed that with Welch sheep the horns of the males are considerably reduced by castration; but the degree depends much on the age at which the operation is performed, as is likewise the case with other animals. Merino rams have large horns, whilst the ewes "generally speaking are without horns"; and in this breed castration seems to produce a somewhat greater effect, so that if performed at an early age the horns "remain almost undeveloped." (18. I am much obliged to Prof. Victor Carus, for having made enquiries for me in Saxony on this subject. H. von Nathusius ('Viehzucht,' 1872, p. 64) says that the horns of sheep castrated at an early period, either altogether disappear or remain as mere rudiments; but I do not know whether he refers to merinos or to ordinary breeds.) On the Guinea coast there is a breed in which the females never bear horns, and, as Mr. Winwood Reade informs me, the rams after castration are quite destitute of them. With cattle, the horns of the males are much altered by castration; for instead of being short and thick, they become longer than those of the cow, but otherwise resemble them. The Antilope bezoartica offers a somewhat analogous case: the males have long straight spiral horns, nearly parallel to each other, and directed backwards; the females occasionally bear horns, but these when present are of a very different shape, for they are not spiral, and spreading widely, bend round with the points forwards. Now it is a remarkable fact that, in the castrated male, as Mr. Blyth informs me, the horns are of the same peculiar shape as in the female, but longer and thicker. If we may judge from analogy, the female probably shews us, in these two cases of cattle and the antelope, the former condition of the horns in some early progenitor of each species. But why castration should lead to the reappearance of an early condition of the horns cannot be explained with any certainty. Nevertheless, it seems probable, that in nearly the same manner as the constitutional disturbance in the offspring, caused by a cross between two distinct species or races, often leads to the reappearance of long-lost characters (19. I have given various experiments and other evidence proving that this is the case, in my 'Variation of Animals and Plants under Domestication,' vol. ii. 1868, pp. 39-47.); so here, the disturbance in the constitution of the individual, resulting from castration, produces the same effect. The tusks of the elephant, in the different species or races, differ according to sex, nearly as do the horns of ruminants. In India and Malacca the males alone are provided with well-developed tusks. The elephant of Ceylon is considered by most naturalists as a distinct race, but by some as a distinct species, and here "not one in a hundred is found with tusks, the few that possess them being exclusively males." (20. Sir J. Emerson Tennent, 'Ceylon,' 1859, vol. ii. p. 274. For Malacca, 'Journal of Indian Archipelago,' vol. iv. p. 357.) The African elephant is undoubtedly distinct, and the female has large well-developed tusks, though not so large as those of the male. These differences in the tusks of the several races and species of elephants--the great variability of the horns of deer, as notably in the wild reindeer--the occasional presence of horns in the female Antilope Bezoartica, and their frequent absence in the female of Antilocapra americana--the presence of two tusks in some few male narwhals--the complete absence of tusks in some female walruses--are all instances of the extreme variability of secondary sexual characters, and of their liability to differ in closely-allied forms. Although tusks and horns appear in all cases to have been primarily developed as sexual weapons, they often serve other purposes. The elephant uses his tusks in attacking the tiger; according to Bruce, he scores the trunks of trees until they can be thrown down easily, and he likewise thus extracts the farinaceous cores of palms; in Africa he often uses one tusk, always the same, to probe the ground and thus ascertain whether it will bear his weight. The common bull defends the herd with his horns; and the elk in Sweden has been known, according to Lloyd, to strike a wolf dead with a single blow of his great horns. Many similar facts could be given. One of the most curious secondary uses to which the horns of an animal may be occasionally put is that observed by Captain Hutton (21. 'Calcutta Journal of Natural History,' vol. ii, 1843, p. 526.) with the wild goat (Capra aegagrus) of the Himalayas and, as it is also said with the ibex, namely that when the male accidentally falls from a height he bends inwards his head, and by alighting on his massive horns, breaks the shock. The female cannot thus use her horns, which are smaller, but from her more quiet disposition she does not need this strange kind of shield so much. Each male animal uses his weapons in his own peculiar fashion. The common ram makes a charge and butts with such force with the bases of his horns, that I have seen a powerful man knocked over like a child. Goats and certain species of sheep, for instance the Ovis cycloceros of Afghanistan (22. Mr. Blyth, in 'Land and Water,' March, 1867, p. 134, on the authority of Capt. Hutton and others. For the wild Pembrokeshire goats, see the 'Field,' 1869, p. 150.), rear on their hind legs, and then not only butt, but "make a cut down and a jerk up, with the ribbed front of their scimitar-shaped horn, as with a sabre. When the O. cycloceros attacked a large domestic ram, who was a noted bruiser, he conquered him by the sheer novelty of his mode of fighting, always closing at once with his adversary, and catching him across the face and nose with a sharp drawing jerk of the head, and then bounding out of the way before the blow could be returned." In Pembrokeshire a male goat, the master of a flock which during several generations had run wild, was known to have killed several males in single combat; this goat possessed enormous horns, measuring thirty-nine inches in a straight line from tip to tip. The common bull, as every one knows, gores and tosses his opponent; but the Italian buffalo is said never to use his horns: he gives a tremendous blow with his convex forehead, and then tramples on his fallen enemy with his knees--an instinct which the common bull does not possess. (23. M. E.M. Bailly, "Sur l'usage des cornes," etc., .Annal des Sciences Nat.' tom. ii. 1824, p. 369.) Hence a dog who pins a buffalo by the nose is immediately crushed. We must, however, remember that the Italian buffalo has been long domesticated, and it is by no means certain that the wild parent-form had similar horns. Mr. Bartlett informs me that when a female Cape buffalo (Bubalus caffer) was turned into an enclosure with a bull of the same species, she attacked him, and he in return pushed her about with great violence. But it was manifest to Mr. Bartlett that, had not the bull shewn dignified forbearance, he could easily have killed her by a single lateral thrust with his immense horns. The giraffe uses his short, hair-covered horns, which are rather longer in the male than in the female, in a curious manner; for, with his long neck, he swings his head to either side, almost upside down, with such force that I have seen a hard plank deeply indented by a single blow. [Fig. 63. Oryx leucoryx, male (from the Knowsley Menagerie).] With antelopes it is sometimes difficult to imagine how they can possibly use their curiously-shaped horns; thus the springboc (Ant. euchore) has rather short upright horns, with the sharp points bent inwards almost at right angles, so as to face each other; Mr. Bartlett does not know how they are used, but suggests that they would inflict a fearful wound down each side of the face of an antagonist. The slightly-curved horns of the Oryx leucoryx (Fig. 63) are directed backwards, and are of such length that their points reach beyond the middle of the back, over which they extend in almost parallel lines. Thus they seem singularly ill-fitted for fighting; but Mr. Bartlett informs me that when two of these animals prepare for battle, they kneel down, with their heads between their fore legs, and in this attitude the horns stand nearly parallel and close to the ground, with the points directed forwards and a little upwards. The combatants then gradually approach each other, and each endeavours to get the upturned points under the body of the other; if one succeeds in doing this, he suddenly springs up, throwing up his head at the same time, and can thus wound or perhaps even transfix his antagonist. Both animals always kneel down, so as to guard as far as possible against this manoeuvre. It has been recorded that one of these antelopes has used his horn with effect even against a lion; yet from being forced to place his head between the forelegs in order to bring the points of the horns forward, he would generally be under a great disadvantage when attacked by any other animal. It is, therefore, not probable that the horns have been modified into their present great length and peculiar position, as a protection against beasts of prey. We can however see that, as soon as some ancient male progenitor of the Oryx acquired moderately long horns, directed a little backwards, he would be compelled, in his battles with rival males, to bend his head somewhat inwards or downwards, as is now done by certain stags; and it is not improbable that he might have acquired the habit of at first occasionally and afterwards of regularly kneeling down. In this case it is almost certain that the males which possessed the longest horns would have had a great advantage over others with shorter horns; and then the horns would gradually have been rendered longer and longer, through sexual selection, until they acquired their present extraordinary length and position. With stags of many kinds the branches of the horns offer a curious case of difficulty; for certainly a single straight point would inflict a much more serious wound than several diverging ones. In Sir Philip Egerton's museum there is a horn of the red-deer (Cervus elaphus), thirty inches in length, with "not fewer than fifteen snags or branches"; and at Moritzburg there is still preserved a pair of antlers of a red-deer, shot in 1699 by Frederick I., one of which bears the astonishing number of thirty-three branches and the other twenty-seven, making altogether sixty branches. Richardson figures a pair of antlers of the wild reindeer with twenty-nine points. (24. On the horns of red-deer, Owen, 'British Fossil Mammals,' 1846, p. 478; Richardson on the horns of the reindeer, 'Fauna Bor. Americana,' 1829, p. 240. I am indebted to Prof. Victor Carus, for the Moritzburg case.) From the manner in which the horns are branched, and more especially from deer being known occasionally to fight together by kicking with their fore-feet (25. Hon. J.D. Caton ('Ottawa Acad. of Nat. Science,' May 1868, p. 9) says that the American deer fight with their fore-feet, after "the question of superiority has been once settled and acknowledged in the herd." Bailly, 'Sur l'Usage des cornes,' 'Annales des Sciences Nat.' tom. ii. 1824, p. 371.), M. Bailly actually comes to the conclusion that their horns are more injurious than useful to them. But this author overlooks the pitched battles between rival males. As I felt much perplexed about the use or advantage of the branches, I applied to Mr. McNeill of Colonsay, who has long and carefully observed the habits of red-deer, and he informs me that he has never seen some of the branches brought into use, but that the brow antlers, from inclining downwards, are a great protection to the forehead, and their points are likewise used in attack. Sir Philip Egerton also informs me both as to red-deer and fallow-deer that, in fighting, they suddenly dash together, and getting their horns fixed against each other's bodies, a desperate struggle ensues. When one is at last forced to yield and turn round, the victor endeavours to plunge his brow antlers into his defeated foe. It thus appears that the upper branches are used chiefly or exclusively for pushing and fencing. Nevertheless in some species the upper branches are used as weapons of offence; when a man was attacked by a wapiti deer (Cervus canadensis) in Judge Caton's park in Ottawa, and several men tried to rescue him, the stag "never raised his head from the ground; in fact he kept his face almost flat on the ground, with his nose nearly between his fore feet, except when he rolled his head to one side to take a new observation preparatory to a plunge." In this position the ends of the horns were directed against his adversaries. "In rolling his head he necessarily raised it somewhat, because his antlers were so long that he could not roll his head without raising them on one side, while, on the other side they touched the ground." The stag by this procedure gradually drove the party of rescuers backwards to a distance of 150 or 200 feet; and the attacked man was killed. (26. See a most interesting account in the Appendix to Hon. J.D. Caton's paper, as above quoted.) [Fig. 64. Strepsiceros Kudu (from Sir Andrew Smith's 'Zoology of South Africa.'] Although the horns of stags are efficient weapons, there can, I think, be no doubt that a single point would have been much more dangerous than a branched antler; and Judge Caton, who has had large experience with deer, fully concurs in this conclusion. Nor do the branching horns, though highly important as a means of defence against rival stags, appear perfectly well adapted for this purpose, as they are liable to become interlocked. The suspicion has therefore crossed my mind that they may serve in part as ornaments. That the branched antlers of stags as well as the elegant lyrated horns of certain antelopes, with their graceful double curvature (Fig. 64), are ornamental in our eyes, no one will dispute. If, then, the horns, like the splendid accoutrements of the knights of old, add to the noble appearance of stags and antelopes, they may have been modified partly for this purpose, though mainly for actual service in battle; but I have no evidence in favour of this belief. An interesting case has lately been published, from which it appears that the horns of a deer in one district in the United States are now being modified through sexual and natural selection. A writer in an excellent American Journal (27. The 'American Naturalist,' Dec. 1869, p. 552.) says, that he has hunted for the last twenty-one years in the Adirondacks, where the Cervus virginianus abounds. About fourteen years ago he first heard of SPIKE-HORN BUCKS. These became from year to year more common; about five years ago he shot one, and afterwards another, and now they are frequently killed. "The spike-horn differs greatly from the common antler of the C. virginianus. It consists of a single spike, more slender than the antler, and scarcely half so long, projecting forward from the brow, and terminating in a very sharp point. It gives a considerable advantage to its possessor over the common buck. Besides enabling him to run more swiftly through the thick woods and underbrush (every hunter knows that does and yearling bucks run much more rapidly than the large bucks when armed with their cumbrous antlers), the spike-horn is a more effective weapon than the common antler. With this advantage the spike-horn bucks are gaining upon the common bucks, and may, in time, entirely supersede them in the Adirondacks. Undoubtedly, the first spike-horn buck was merely an accidental freak of nature. But his spike-horns gave him an advantage, and enabled him to propagate his peculiarity. His descendants having a like advantage, have propagated the peculiarity in a constantly increasing ratio, till they are slowly crowding the antlered deer from the region they inhabit." A critic has well objected to this account by asking, why, if the simple horns are now so advantageous, were the branched antlers of the parent-form ever developed? To this I can only answer by remarking, that a new mode of attack with new weapons might be a great advantage, as shewn by the case of the Ovis cycloceros, who thus conquered a domestic ram famous for his fighting power. Though the branched antlers of a stag are well adapted for fighting with his rivals, and though it might be an advantage to the prong-horned variety slowly to acquire long and branched horns, if he had to fight only with others of the same kind, yet it by no means follows that branched horns would be the best fitted for conquering a foe differently armed. In the foregoing case of the Oryx leucoryx, it is almost certain that the victory would rest with an antelope having short horns, and who therefore did not need to kneel down, though an oryx might profit by having still longer horns, if he fought only with his proper rivals. Male quadrupeds, which are furnished with tusks, use them in various ways, as in the case of horns. The boar strikes laterally and upwards; the musk-deer downwards with serious effect. (28. Pallas, 'Spicilegia Zoologica,' fasc. xiii. 1779, p. 18.) The walrus, though having so short a neck and so unwieldy a body, "can strike either upwards, or downwards, or sideways, with equal dexterity." (29. Lamont, 'Seasons with the Sea-Horses,' 1861, p. 141.) I was informed by the late Dr. Falconer, that the Indian elephant fights in a different manner according to the position and curvature of his tusks. When they are directed forwards and upwards he is able to fling a tiger to a great distance--it is said to even thirty feet; when they are short and turned downwards he endeavours suddenly to pin the tiger to the ground and, in consequence, is dangerous to the rider, who is liable to be jerked off the howdah. (30. See also Corse ('Philosophical Transactions,' 1799, p. 212) on the manner in which the short-tusked Mooknah variety attacks other elephants.) Very few male quadrupeds possess weapons of two distinct kinds specially adapted for fighting with rival males. The male muntjac-deer (Cervulus), however, offers an exception, as he is provided with horns and exserted canine teeth. But we may infer from what follows that one form of weapon has often been replaced in the course of ages by another. With ruminants the development of horns generally stands in an inverse relation with that of even moderately developed canine teeth. Thus camels, guanacoes, chevrotains, and musk-deer, are hornless, and they have efficient canines; these teeth being "always of smaller size in the females than in the males." The Camelidae have, in addition to their true canines, a pair of canine-shaped incisors in their upper jaws. (31. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 349.) Male deer and antelopes, on the other hand, possess horns, and they rarely have canine teeth; and these, when present, are always of small size, so that it is doubtful whether they are of any service in their battles. In Antilope montana they exist only as rudiments in the young male, disappearing as he grows old; and they are absent in the female at all ages; but the females of certain other antelopes and of certain deer have been known occasionally to exhibit rudiments of these teeth. (32. See Ruppell (in 'Proc. Zoolog. Soc.' Jan. 12, 1836, p. 3) on the canines in deer and antelopes, with a note by Mr. Martin on a female American deer. See also Falconer ('Palaeont. Memoirs and Notes,' vol. i. 1868, p. 576) on canines in an adult female deer. In old males of the musk-deer the canines (Pallas, 'Spic. Zoolog.' fasc. xiii. 1779, p. 18) sometimes grow to the length of three inches, whilst in old females a rudiment projects scarcely half an inch above the gums.) Stallions have small canine teeth, which are either quite absent or rudimentary in the mare; but they do not appear to be used in fighting, for stallions bite with their incisors, and do not open their mouths wide like camels and guanacoes. Whenever the adult male possesses canines, now inefficient, whilst the female has either none or mere rudiments, we may conclude that the early male progenitor of the species was provided with efficient canines, which have been partially transferred to the females. The reduction of these teeth in the males seems to have followed from some change in their manner of fighting, often (but not in the horse) caused by the development of new weapons. Tusks and horns are manifestly of high importance to their possessors, for their development consumes much organised matter. A single tusk of the Asiatic elephant--one of the extinct woolly species--and of the African elephant, have been known to weigh respectively 150, 160, and 180 pounds; and even greater weights have been given by some authors. (33. Emerson Tennent, 'Ceylon,' 1859, vol. ii. p. 275; Owen, 'British Fossil Mammals,' 1846, p. 245.) With deer, in which the horns are periodically renewed, the drain on the constitution must be greater; the horns, for instance, of the moose weigh from fifty to sixty pounds, and those of the extinct Irish elk from sixty to seventy pounds--the skull of the latter weighing on an average only five pounds and a quarter. Although the horns are not periodically renewed in sheep, yet their development, in the opinion of many agriculturists, entails a sensible loss to the breeder. Stags, moreover, in escaping from beasts of prey are loaded with an additional weight for the race, and are greatly retarded in passing through a woody country. The moose, for instance, with horns extending five and a half feet from tip to tip, although so skilful in their use that he will not touch or break a twig when walking quietly, cannot act so dexterously whilst rushing away from a pack of wolves. "During his progress he holds his nose up, so as to lay the horns horizontally back; and in this attitude cannot see the ground distinctly." (34. Richardson, 'Fauna Bor. Americana,' on the moose, Alces palmata, pp. 236, 237; on the expanse of the horns, 'Land and Water,' 1869, p. 143. See also Owen, 'British Fossil Mammals,' on the Irish elk, pp. 447, 455.) The tips of the horns of the great Irish elk were actually eight feet apart! Whilst the horns are covered with velvet, which lasts with red-deer for about twelve weeks, they are extremely sensitive to a blow; so that in Germany the stags at this time somewhat change their habits, and avoiding dense forests, frequent young woods and low thickets. (35. 'Forest Creatures,' by C. Boner, 1861, p. 60.) These facts remind us that male birds have acquired ornamental plumes at the cost of retarded flight, and other ornaments at the cost of some loss of power in their battles with rival males. With mammals, when, as is often the case, the sexes differ in size, the males are almost always larger and stronger. I am informed by Mr. Gould that this holds good in a marked manner with the marsupials of Australia, the males of which appear to continue growing until an unusually late age. But the most extraordinary case is that of one of the seals (Callorhinus ursinus), a full-grown female weighing less than one-sixth of a full-grown male. (36. See the very interesting paper by Mr. J.A. Allen in 'Bull. Mus. Comp. Zoology of Cambridge, United States,' vol. ii. No. 1, p. 82. The weights were ascertained by a careful observer, Capt. Bryant. Dr. Gill in 'The American Naturalist,' January, 1871, Prof. Shaler on the relative size of the sexes of whales, 'American Naturalist,' January, 1873.) Dr. Gill remarks that it is with the polygamous seals, the males of which are well known to fight savagely together, that the sexes differ much in size; the monogamous species differing but little. Whales also afford evidence of the relation existing between the pugnacity of the males and their large size compared with that of the female; the males of the right-whales do not fight together, and they are not larger, but rather smaller, than their females; on the other hand, male sperm-whales fight much together, and their bodies are "often found scarred with the imprint of their rival's teeth," and they are double the size of the females. The greater strength of the male, as Hunter long ago remarked (37. 'Animal Economy,' p. 45.), is invariably displayed in those parts of the body which are brought into action in fighting with rival males--for instance, in the massive neck of the bull. Male quadrupeds are also more courageous and pugnacious than the females. There can be little doubt that these characters have been gained, partly through sexual selection, owing to a long series of victories, by the stronger and more courageous males over the weaker, and partly through the inherited effects of use. It is probable that the successive variations in strength, size, and courage, whether due to mere variability or to the effects of use, by the accumulation of which male quadrupeds have acquired these characteristic qualities, occurred rather late in life, and were consequently to a large extent limited in their transmission to the same sex. From these considerations I was anxious to obtain information as to the Scotch deer-hound, the sexes of which differ more in size than those of any other breed (though blood-hounds differ considerably), or than in any wild canine species known to me. Accordingly, I applied to Mr. Cupples, well known for his success with this breed, who has weighed and measured many of his own dogs, and who has with great kindness collected for me the following facts from various sources. Fine male dogs, measured at the shoulder, range from 28 inches, which is low, to 33 or even 34 inches in height; and in weight from 80 pounds, which is light, to 120 pounds, or even more. The females range in height from 23 to 27, or even to 28 inches; and in weight from 50 to 70, or even 80 pounds. (38. See also Richardson's 'Manual on the Dog,' p. 59. Much valuable information on the Scottish deer-hound is given by Mr. McNeill, who first called attention to the inequality in size between the sexes, in Scrope's 'Art of Deer-Stalking.' I hope that Mr. Cupples will keep to his intention of publishing a full account and history of this famous breed.) Mr. Cupples concludes that from 95 to 100 pounds for the male, and 70 for the female, would be a safe average; but there is reason to believe that formerly both sexes attained a greater weight. Mr. Cupples has weighed puppies when a fortnight old; in one litter the average weight of four males exceeded that of two females by six and a half ounces; in another litter the average weight of four males exceeded that of one female by less than one ounce; the same males when three weeks old, exceeded the female by seven and a half ounces, and at the age of six weeks by nearly fourteen ounces. Mr. Wright of Yeldersley House, in a letter to Mr. Cupples, says: "I have taken notes on the sizes and weights of puppies of many litters, and as far as my experience goes, dog-puppies as a rule differ very little from bitches till they arrive at about five or six months old; and then the dogs begin to increase, gaining upon the bitches both in weight and size. At birth, and for several weeks afterwards, a bitch-puppy will occasionally be larger than any of the dogs, but they are invariably beaten by them later." Mr. McNeill, of Colonsay, concludes that "the males do not attain their full growth till over two years old, though the females attain it sooner." According to Mr. Cupples' experience, male dogs go on growing in stature till they are from twelve to eighteen months old, and in weight till from eighteen to twenty-four months old; whilst the females cease increasing in stature at the age of from nine to fourteen or fifteen months, and in weight at the age of from twelve to fifteen months. From these various statements it is clear that the full difference in size between the male and female Scotch deer-hound is not acquired until rather late in life. The males almost exclusively are used for coursing, for, as Mr. McNeill informs me, the females have not sufficient strength and weight to pull down a full-grown deer. From the names used in old legends, it appears, as I hear from Mr. Cupples, that, at a very ancient period, the males were the most celebrated, the females being mentioned only as the mothers of famous dogs. Hence, during many generations, it is the male which has been chiefly tested for strength, size, speed, and courage, and the best will have been bred from. As, however, the males do not attain their full dimensions until rather late in life, they will have tended, in accordance with the law often indicated, to transmit their characters to their male offspring alone; and thus the great inequality in size between the sexes of the Scotch deer-hound may probably be accounted for. [Fig. 65. Head of Common wild boar, in prime of life (from Brehm).] The males of some few quadrupeds possess organs or parts developed solely as a means of defence against the attacks of other males. Some kinds of deer use, as we have seen, the upper branches of their horns chiefly or exclusively for defending themselves; and the Oryx antelope, as I am informed by Mr. Bartlett, fences most skilfully with his long, gently curved horns; but these are likewise used as organs of offence. The same observer remarks that rhinoceroses in fighting, parry each other's sidelong blows with their horns, which clatter loudly together, as do the tusks of boars. Although wild boars fight desperately, they seldom, according to Brehm, receive fatal wounds, as the blows fall on each other's tusks, or on the layer of gristly skin covering the shoulder, called by the German hunters, the shield; and here we have a part specially modified for defence. With boars in the prime of life (Fig. 65) the tusks in the lower jaw are used for fighting, but they become in old age, as Brehm states, so much curved inwards and upwards over the snout that they can no longer be used in this way. They may, however, still serve, and even more effectively, as a means of defence. In compensation for the loss of the lower tusks as weapons of offence, those in the upper jaw, which always project a little laterally, increase in old age so much in length and curve so much upwards that they can be used for attack. Nevertheless, an old boar is not so dangerous to man as one at the age of six or seven years. (39. Brehm, 'Thierleben,' B. ii. ss. 729-732.) [Fig. 66. Skull of the Babirusa Pig (from Wallace's 'Malay Archipelago').] In the full-grown male Babirusa pig of Celebes (Fig. 66), the lower tusks are formidable weapons, like those of the European boar in the prime of life, whilst the upper tusks are so long and have their points so much curled inwards, sometimes even touching the forehead, that they are utterly useless as weapons of attack. They more nearly resemble horns than teeth, and are so manifestly useless as teeth that the animal was formerly supposed to rest his head by hooking them on to a branch! Their convex surfaces, however, if the head were held a little laterally, would serve as an excellent guard; and hence, perhaps, it is that in old animals they "are generally broken off, as if by fighting." (40. See Mr. Wallace's interesting account of this animal, 'The Malay Archipelago,' 1869, vol. i. p. 435.) Here, then, we have the curious case of the upper tusks of the Babirusa regularly assuming during the prime of life a structure which apparently renders them fitted only for defence; whilst in the European boar the lower tusks assume in a less degree and only during old age nearly the same form, and then serve in like manner solely for defence. [Fig. 67. Head of female Aethiopian wart-hog, from 'Proc. Zool. Soc.' 1869, shewing the same characters as the male, though on a reduced scale. N.B. When the engraving was first made, I was under the impression that it represented the male.] In the wart-hog (see Phacochoerus aethiopicus, Fig. 67) the tusks in the upper jaw of the male curve upwards during the prime of life, and from being pointed serve as formidable weapons. The tusks in the lower jaw are sharper than those in the upper, but from their shortness it seems hardly possible that they can be used as weapons of attack. They must, however, greatly strengthen those in the upper jaw, from being ground so as to fit closely against their bases. Neither the upper nor the lower tusks appear to have been specially modified to act as guards, though no doubt they are to a certain extent used for this purpose. But the wart-hog is not destitute of other special means of protection, for it has, on each side of the face, beneath the eyes, a rather stiff, yet flexible, cartilaginous, oblong pad (Fig. 67), which projects two or three inches outwards; and it appeared to Mr. Bartlett and myself, when viewing the living animal, that these pads, when struck from beneath by the tusks of an opponent, would be turned upwards, and would thus admirably protect the somewhat prominent eyes. I may add, on the authority of Mr. Bartlett, that these boars when fighting stand directly face to face. Lastly, the African river-hog (Potomochoerus penicillatus) has a hard cartilaginous knob on each side of the face beneath the eyes, which answers to the flexible pad of the wart-hog; it has also two bony prominences on the upper jaw above the nostrils. A boar of this species in the Zoological Gardens recently broke into the cage of the wart-hog. They fought all night long, and were found in the morning much exhausted, but not seriously wounded. It is a significant fact, as shewing the purposes of the above-described projections and excrescences, that these were covered with blood, and were scored and abraded in an extraordinary manner. Although the males of so many members of the pig family are provided with weapons, and as we have just seen with means of defence, these weapons seem to have been acquired within a rather late geological period. Dr. Forsyth Major specifies (41. 'Atti della Soc. Italiana di Sc. Nat.' 1873, vol. xv. fasc. iv.) several miocene species, in none of which do the tusks appear to have been largely developed in the males; and Professor Rutimeyer was formerly struck with this same fact. The mane of the lion forms a good defence against the attacks of rival lions, the one danger to which he is liable; for the males, as Sir A. Smith informs me, engage in terrible battles, and a young lion dares not approach an old one. In 1857 a tiger at Bromwich broke into the cage of a lion and a fearful scene ensued: "the lion's mane saved his neck and head from being much injured, but the tiger at last succeeded in ripping up his belly, and in a few minutes he was dead." (42. 'The Times,' Nov. 10, 1857. In regard to the Canada lynx, see Audubon and Bachman, 'Quadrupeds of North America,' 1846, p. 139.) The broad ruff round the throat and chin of the Canadian lynx (Felis canadensis) is much longer in the male than in the female; but whether it serves as a defence I do not know. Male seals are well known to fight desperately together, and the males of certain kinds (Otaria jubata) (43. Dr. Murie, on Otaria, 'Proc. Zoolog. Soc.' 1869, p. 109. Mr. J.A. Allen, in the paper above quoted (p. 75), doubts whether the hair, which is longer on the neck in the male than in the female, deserves to be called a mane.) have great manes, whilst the females have small ones or none. The male baboon of the Cape of Good Hope (Cynocephalus porcarius) has a much longer mane and larger canine teeth than the female; and the mane probably serves as a protection, for, on asking the keepers in the Zoological Gardens, without giving them any clue to my object, whether any of the monkeys especially attacked each other by the nape of the neck, I was answered that this was not the case, except with the above baboon. In the Hamadryas baboon, Ehrenberg compares the mane of the adult male to that of a young lion, whilst in the young of both sexes and in the female the mane is almost absent. It appeared to me probable that the immense woolly mane of the male American bison, which reaches almost to the ground, and is much more developed in the males than in the females, served as a protection to them in their terrible battles; but an experienced hunter told Judge Caton that he had never observed anything which favoured this belief. The stallion has a thicker and fuller mane than the mare; and I have made particular inquiries of two great trainers and breeders, who have had charge of many entire horses, and am assured that they "invariably endeavour to seize one another by the neck." It does not, however, follow from the foregoing statements, that when the hair on the neck serves as a defence, that it was originally developed for this purpose, though this is probable in some cases, as in that of the lion. I am informed by Mr. McNeill that the long hairs on the throat of the stag (Cervus elaphus) serve as a great protection to him when hunted, for the dogs generally endeavour to seize him by the throat; but it is not probable that these hairs were specially developed for this purpose; otherwise the young and the females would have been equally protected. CHOICE IN PAIRING BY EITHER SEX OF QUADRUPEDS. Before describing in the next chapter, the differences between the sexes in voice, odours emitted, and ornaments, it will be convenient here to consider whether the sexes exert any choice in their unions. Does the female prefer any particular male, either before or after the males may have fought together for supremacy; or does the male, when not a polygamist, select any particular female? The general impression amongst breeders seems to be that the male accepts any female; and this owing to his eagerness, is, in most cases, probably the truth. Whether the female as a general rule indifferently accepts any male is much more doubtful. In the fourteenth chapter, on Birds, a considerable body of direct and indirect evidence was advanced, shewing that the female selects her partner; and it would be a strange anomaly if female quadrupeds, which stand higher in the scale and have higher mental powers, did not generally, or at least often, exert some choice. The female could in most cases escape, if wooed by a male that did not please or excite her; and when pursued by several males, as commonly occurs, she would often have the opportunity, whilst they were fighting together, of escaping with some one male, or at least of temporarily pairing with him. This latter contingency has often been observed in Scotland with female red-deer, as I am informed by Sir Philip Egerton and others. (44. Mr. Boner, in his excellent description of the habits of the red-deer in Germany ('Forest Creatures,' 1861, p. 81) says, "while the stag is defending his rights against one intruder, another invades the sanctuary of his harem, and carries off trophy after trophy." Exactly the same thing occurs with seals; see Mr. J.A. Allen, ibid. p. 100.) It is scarcely possible that much should be known about female quadrupeds in a state of nature making any choice in their marriage unions. The following curious details on the courtship of one of the eared seals (Callorhinus ursinus) are given (45. Mr. J.A. Allen in 'Bull. Mus. Comp. Zoolog. of Cambridge, United States,' vol. ii. No. 1, p. 99.) on the authority of Capt. Bryant, who had ample opportunities for observation. He says, "Many of the females on their arrival at the island where they breed appear desirous of returning to some particular male, and frequently climb the outlying rocks to overlook the rookeries, calling out and listening as if for a familiar voice. Then changing to another place they do the same again...As soon as a female reaches the shore, the nearest male goes down to meet her, making meanwhile a noise like the clucking of a hen to her chickens. He bows to her and coaxes her until he gets between her and the water so that she cannot escape him. Then his manner changes, and with a harsh growl he drives her to a place in his harem. This continues until the lower row of harems is nearly full. Then the males higher up select the time when their more fortunate neighbours are off their guard to steal their wives. This they do by taking them in their mouths and lifting them over the heads of the other females, and carefully placing them in their own harem, carrying them as cats do their kittens. Those still higher up pursue the same method until the whole space is occupied. Frequently a struggle ensues between two males for the possession of the same female, and both seizing her at once pull her in two or terribly lacerate her with their teeth. When the space is all filled, the old male walks around complacently reviewing his family, scolding those who crowd or disturb the others, and fiercely driving off all intruders. This surveillance always keeps him actively occupied." As so little is known about the courtship of animals in a state of nature, I have endeavoured to discover how far our domesticated quadrupeds evince any choice in their unions. Dogs offer the best opportunity for observation, as they are carefully attended to and well understood. Many breeders have expressed a strong opinion on this head. Thus, Mr. Mayhew remarks, "The females are able to bestow their affections; and tender recollections are as potent over them as they are known to be in other cases, where higher animals are concerned. Bitches are not always prudent in their loves, but are apt to fling themselves away on curs of low degree. If reared with a companion of vulgar appearance, there often springs up between the pair a devotion which no time can afterwards subdue. The passion, for such it really is, becomes of a more than romantic endurance." Mr. Mayhew, who attended chiefly to the smaller breeds, is convinced that the females are strongly attracted by males of a large size. (46. 'Dogs: their Management,' by E. Mayhew, M.R.C.V.S., 2nd ed., 1864, pp. 187-192.) The well-known veterinary Blaine states (47. Quoted by Alex. Walker, 'On Intermarriage,' 1838, p. 276; see also p. 244.) that his own female pug dog became so attached to a spaniel, and a female setter to a cur, that in neither case would they pair with a dog of their own breed until several weeks had elapsed. Two similar and trustworthy accounts have been given me in regard to a female retriever and a spaniel, both of which became enamoured with terrier-dogs. Mr. Cupples informs me that he can personally vouch for the accuracy of the following more remarkable case, in which a valuable and wonderfully-intelligent female terrier loved a retriever belonging to a neighbour to such a degree, that she had often to be dragged away from him. After their permanent separation, although repeatedly shewing milk in her teats, she would never acknowledge the courtship of any other dog, and to the regret of her owner never bore puppies. Mr. Cupples also states, that in 1868, a female deerhound in his kennel thrice produced puppies, and on each occasion shewed a marked preference for one of the largest and handsomest, but not the most eager, of four deerhounds living with her, all in the prime of life. Mr. Cupples has observed that the female generally favours a dog whom she has associated with and knows; her shyness and timidity at first incline her against a strange dog. The male, on the contrary, seems rather inclined towards strange females. It appears to be rare when the male refuses any particular female, but Mr. Wright, of Yeldersley House, a great breeder of dogs, informs me that he has known some instances; he cites the case of one of his own deerhounds, who would not take any notice of a particular female mastiff, so that another deerhound had to be employed. It would be superfluous to give, as I could, other instances, and I will only add that Mr. Barr, who has carefully bred many bloodhounds, states that in almost every instance particular individuals of opposite sexes shew a decided preference for each other. Finally, Mr. Cupples, after attending to this subject for another year, has written to me, "I have had full confirmation of my former statement, that dogs in breeding form decided preferences for each other, being often influenced by size, bright colour, and individual characters, as well as by the degree of their previous familiarity." In regard to horses, Mr. Blenkiron, the greatest breeder of race-horses in the world, informs me that stallions are so frequently capricious in their choice, rejecting one mare and without any apparent cause taking to another, that various artifices have to be habitually used. The famous Monarque, for instance, would never consciously look at the dam of Gladiateur, and a trick had to be practised. We can partly see the reason why valuable race-horse stallions, which are in such demand as to be exhausted, should be so particular in their choice. Mr. Blenkiron has never known a mare reject a horse; but this has occurred in Mr. Wright's stable, so that the mare had to be cheated. Prosper Lucas (48. 'Traité de l'Héréd. Nat.' tom. ii. 1850, p. 296.) quotes various statements from French authorities, and remarks, "On voit des étalons qui s'eprennent d'une jument, et negligent toutes les autres." He gives, on the authority of Baelen, similar facts in regard to bulls; and Mr. H. Reeks assures me that a famous short-horn bull belonging to his father "invariably refused to be matched with a black cow." Hoffberg, in describing the domesticated reindeer of Lapland says, "Foeminae majores et fortiores mares prae caeteris admittunt, ad eos confugiunt, a junioribus agitatae, qui hos in fugam conjiciunt." (49. 'Amoenitates Acad.' vol. iv. 1788, p. 160.) A clergyman, who has bred many pigs, asserts that sows often reject one boar and immediately accept another. From these facts there can be no doubt that, with most of our domesticated quadrupeds, strong individual antipathies and preferences are frequently exhibited, and much more commonly by the female than by the male. This being the case, it is improbable that the unions of quadrupeds in a state of nature should be left to mere chance. It is much more probable that the females are allured or excited by particular males, who possess certain characters in a higher degree than other males; but what these characters are, we can seldom or never discover with certainty. CHAPTER XVIII. SECONDARY SEXUAL CHARACTERS OF MAMMALS--continued. Voice--Remarkable sexual peculiarities in seals--Odour--Development of the hair--Colour of the hair and skin--Anomalous case of the female being more ornamented than the male--Colour and ornaments due to sexual selection--Colour acquired for the sake of protection--Colour, though common to both sexes, often due to sexual selection--On the disappearance of spots and stripes in adult quadrupeds--On the colours and ornaments of the Quadrumana--Summary. Quadrupeds use their voices for various purposes, as a signal of danger, as a call from one member of a troop to another, or from the mother to her lost offspring, or from the latter for protection to their mother; but such uses need not here be considered. We are concerned only with the difference between the voices of the sexes, for instance between that of the lion and lioness, or of the bull and cow. Almost all male animals use their voices much more during the rutting-season than at any other time; and some, as the giraffe and porcupine (1. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 585.), are said to be completely mute excepting at this season. As the throats (i.e. the larynx and thyroid bodies (2. Ibid. p. 595.)) of stags periodically become enlarged at the beginning of the breeding-season, it might be thought that their powerful voices must be somehow of high importance to them; but this is very doubtful. From information given to me by two experienced observers, Mr. McNeill and Sir P. Egerton, it seems that young stags under three years old do not roar or bellow; and that the old ones begin bellowing at the commencement of the breeding-season, at first only occasionally and moderately, whilst they restlessly wander about in search of the females. Their battles are prefaced by loud and prolonged bellowing, but during the actual conflict they are silent. Animals of all kinds which habitually use their voices utter various noises under any strong emotion, as when enraged and preparing to fight; but this may merely be the result of nervous excitement, which leads to the spasmodic contraction of almost all the muscles of the body, as when a man grinds his teeth and clenches his fists in rage or agony. No doubt stags challenge each other to mortal combat by bellowing; but those with the more powerful voices, unless at the same time the stronger, better-armed, and more courageous, would not gain any advantage over their rivals. It is possible that the roaring of the lion may be of some service to him by striking terror into his adversary; for when enraged he likewise erects his mane and thus instinctively tries to make himself appear as terrible as possible. But it can hardly be supposed that the bellowing of the stag, even if it be of service to him in this way, can have been important enough to have led to the periodical enlargement of the throat. Some writers suggest that the bellowing serves as a call to the female; but the experienced observers above quoted inform me that female deer do not search for the male, though the males search eagerly for the females, as indeed might be expected from what we know of the habits of other male quadrupeds. The voice of the female, on the other hand, quickly brings to her one or more stags (3. See, for instance, Major W. Ross King ('The Sportsman in Canada,' 1866, pp. 53, 131) on the habits of the moose and wild reindeer.), as is well known to the hunters who in wild countries imitate her cry. If we could believe that the male had the power to excite or allure the female by his voice, the periodical enlargement of his vocal organs would be intelligible on the principle of sexual selection, together with inheritance limited to the same sex and season; but we have no evidence in favour of this view. As the case stands, the loud voice of the stag during the breeding-season does not seem to be of any special service to him, either during his courtship or battles, or in any other way. But may we not believe that the frequent use of the voice, under the strong excitement of love, jealousy, and rage, continued during many generations, may at last have produced an inherited effect on the vocal organs of the stag, as well as of other male animals? This appears to me, in our present state of knowledge, the most probable view. The voice of the adult male gorilla is tremendous, and he is furnished with a laryngeal sack, as is the adult male orang. (4. Owen 'Anatomy of Vertebrates,' vol. iii. p. 600.) The gibbons rank among the noisiest of monkeys, and the Sumatra species (Hylobates syndactylus) is also furnished with an air sack; but Mr. Blyth, who has had opportunities for observation, does not believe that the male is noisier than the female. Hence, these latter monkeys probably use their voices as a mutual call; and this is certainly the case with some quadrupeds, for instance the beaver. (5. Mr. Green, in 'Journal of Linnean Society,' vol. x. 'Zoology,' 1869, note 362.) Another gibbon, the H. agilis, is remarkable, from having the power of giving a complete and correct octave of musical notes (6. C.L. Martin, 'General Introduction to the Natural History of Mamm. Animals,' 1841, p. 431.), which we may reasonably suspect serves as a sexual charm; but I shall have to recur to this subject in the next chapter. The vocal organs of the American Mycetes caraya are one-third larger in the male than in the female, and are wonderfully powerful. These monkeys in warm weather make the forests resound at morning and evening with their overwhelming voices. The males begin the dreadful concert, and often continue it during many hours, the females sometimes joining in with their less powerful voices. An excellent observer, Rengger (7. 'Naturgeschichte der Säugethiere von Paraguay,' 1830, ss. 15, 21.), could not perceive that they were excited to begin by any special cause; he thinks that, like many birds, they delight in their own music, and try to excel each other. Whether most of the foregoing monkeys have acquired their powerful voices in order to beat their rivals and charm the females--or whether the vocal organs have been strengthened and enlarged through the inherited effects of long-continued use without any particular good being thus gained--I will not pretend to say; but the former view, at least in the case of the Hylobates agilis, seems the most probable. I may here mention two very curious sexual peculiarities occurring in seals, because they have been supposed by some writers to affect the voice. The nose of the male sea-elephant (Macrorhinus proboscideus) becomes greatly elongated during the breeding-season, and can then be erected. In this state it is sometimes a foot in length. The female is not thus provided at any period of life. The male makes a wild, hoarse, gurgling noise, which is audible at a great distance and is believed to be strengthened by the proboscis; the voice of the female being different. Lesson compares the erection of the proboscis, with the swelling of the wattles of male gallinaceous birds whilst courting the females. In another allied kind of seal, the bladder-nose (Cystophora cristata), the head is covered by a great hood or bladder. This is supported by the septum of the nose, which is produced far backwards and rises into an internal crest seven inches in height. The hood is clothed with short hair, and is muscular; can be inflated until it more than equals the whole head in size! The males when rutting, fight furiously on the ice, and their roaring "is said to be sometimes so loud as to be heard four miles off." When attacked they likewise roar or bellow; and whenever irritated the bladder is inflated and quivers. Some naturalists believe that the voice is thus strengthened, but various other uses have been assigned to this extraordinary structure. Mr. R. Brown thinks that it serves as a protection against accidents of all kinds; but this is not probable, for, as I am assured by Mr. Lamont who killed 600 of these animals, the hood is rudimentary in the females, and it is not developed in the males during youth. (8. On the sea-elephant, see an article by Lesson, in 'Dict. Class. Hist. Nat.' tom. xiii. p. 418. For the Cystophora, or Stemmatopus, see Dr. Dekay, 'Annals of Lyceum of Nat. Hist.' New York, vol. i. 1824, p. 94. Pennant has also collected information from the sealers on this animal. The fullest account is given by Mr. Brown, in 'Proc. Zoolog. Soc.' 1868, p. 435.) ODOUR. With some animals, as with the notorious skunk of America, the overwhelming odour which they emit appears to serve exclusively as a defence. With shrew-mice (Sorex) both sexes possess abdominal scent-glands, and there can be little doubt, from the rejection of their bodies by birds and beasts of prey, that the odour is protective; nevertheless, the glands become enlarged in the males during the breeding-season. In many other quadrupeds the glands are of the same size in both sexes (9. As with the castoreum of the beaver, see Mr. L.H. Morgan's most interesting work, 'The American Beaver,' 1868, p. 300. Pallas ('Spic. Zoolog.' fasc. viii. 1779, p. 23) has well discussed the odoriferous glands of mammals. Owen ('Anat. of Vertebrates,' vol. iii. p. 634) also gives an account of these glands, including those of the elephant, and (p. 763) those of shrew-mice. On bats, Mr. Dobson in 'Proceedings of the Zoological Society' 1873, p. 241.), but their uses are not known. In other species the glands are confined to the males, or are more developed than in the females; and they almost always become more active during the rutting-season. At this period the glands on the sides of the face of the male elephant enlarge, and emit a secretion having a strong musky odour. The males, and rarely the females, of many kinds of bats have glands and protrudable sacks situated in various parts; and it is believed that these are odoriferous. The rank effluvium of the male goat is well known, and that of certain male deer is wonderfully strong and persistent. On the banks of the Plata I perceived the air tainted with the odour of the male Cervus campestris, at half a mile to leeward of a herd; and a silk handkerchief, in which I carried home a skin, though often used and washed, retained, when first unfolded, traces of the odour for one year and seven months. This animal does not emit its strong odour until more than a year old, and if castrated whilst young never emits it. (10. Rengger, 'Naturgeschichte der Säugethiere von Paraguay,' 1830, s. 355. This observer also gives some curious particulars in regard to the odour.) Besides the general odour, permeating the whole body of certain ruminants (for instance, Bos moschatus) in the breeding-season, many deer, antelopes, sheep, and goats possess odoriferous glands in various situations, more especially on their faces. The so-called tear-sacks, or suborbital pits, come under this head. These glands secrete a semi-fluid fetid matter which is sometimes so copious as to stain the whole face, as I have myself seen in an antelope. They are "usually larger in the male than in the female, and their development is checked by castration." (11. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 632. See also Dr. Murie's observations on those glands in the 'Proc. Zoolog. Soc.' 1870, p. 340. Desmarest, 'On the Antilope subgutturosa, 'Mammalogie,' 1820, p. 455.) According to Desmarest they are altogether absent in the female of Antilope subgutturosa. Hence, there can be no doubt that they stand in close relation with the reproductive functions. They are also sometimes present, and sometimes absent, in nearly allied forms. In the adult male musk-deer (Moschus moschiferus), a naked space round the tail is bedewed with an odoriferous fluid, whilst in the adult female, and in the male until two years old, this space is covered with hair and is not odoriferous. The proper musk-sack of this deer is from its position necessarily confined to the male, and forms an additional scent-organ. It is a singular fact that the matter secreted by this latter gland, does not, according to Pallas, change in consistence, or increase in quantity, during the rutting-season; nevertheless this naturalist admits that its presence is in some way connected with the act of reproduction. He gives, however, only a conjectural and unsatisfactory explanation of its use. (12. Pallas, 'Spicilegia Zoolog.' fasc. xiii. 1799, p. 24; Desmoulins, 'Dict. Class. d'Hist. Nat.' tom. iii. p. 586.) In most cases, when only the male emits a strong odour during the breeding-season, it probably serves to excite or allure the female. We must not judge on this head by our own taste, for it is well known that rats are enticed by certain essential oils, and cats by valerian, substances far from agreeable to us; and that dogs, though they will not eat carrion, sniff and roll on it. From the reasons given when discussing the voice of the stag, we may reject the idea that the odour serves to bring the females from a distance to the males. Active and long-continued use cannot here have come into play, as in the case of the vocal organs. The odour emitted must be of considerable importance to the male, inasmuch as large and complex glands, furnished with muscles for everting the sack, and for closing or opening the orifice, have in some cases been developed. The development of these organs is intelligible through sexual selection, if the most odoriferous males are the most successful in winning the females, and in leaving offspring to inherit their gradually perfected glands and odours. DEVELOPMENT OF THE HAIR. We have seen that male quadrupeds often have the hair on their necks and shoulders much more developed than the females; and many additional instances could be given. This sometimes serves as a defence to the male during his battles; but whether the hair in most cases has been specially developed for this purpose, is very doubtful. We may feel almost certain that this is not the case, when only a thin and narrow crest runs along the back; for a crest of this kind would afford scarcely any protection, and the ridge of the back is not a place likely to be injured; nevertheless such crests are sometimes confined to the males, or are much more developed in them than in the females. Two antelopes, the Tragelaphus scriptus (13. Dr. Gray, 'Gleanings from the Menagerie at Knowsley,' pl. 28.) (Fig. 70) and Portax picta may be given as instances. When stags, and the males of the wild goat, are enraged or terrified, these crests stand erect (14. Judge Caton on the Wapiti, 'Transact. Ottawa Acad. Nat. Sciences,' 1868, pp. 36, 40; Blyth, 'Land and Water,' on Capra aegagrus 1867, p. 37.); but it cannot be supposed that they have been developed merely for the sake of exciting fear in their enemies. One of the above-named antelopes, the Portax picta, has a large well-defined brush of black hair on the throat, and this is much larger in the male than in the female. In the Ammotragus tragelaphus of North Africa, a member of the sheep-family, the fore-legs are almost concealed by an extraordinary growth of hair, which depends from the neck and upper halves of the legs; but Mr. Bartlett does not believe that this mantle is of the least use to the male, in whom it is much more developed than in the female. [Fig. 68. Pithecia satanas, male (from Brehm).] Male quadrupeds of many kinds differ from the females in having more hair, or hair of a different character, on certain parts of their faces. Thus the bull alone has curled hair on the forehead. (15. Hunter's 'Essays and Observations,' edited by Owen, 1861. vol. i. p. 236.) In three closely-allied sub-genera of the goat family, only the males possess beards, sometimes of large size; in two other sub-genera both sexes have a beard, but it disappears in some of the domestic breeds of the common goat; and neither sex of the Hemitragus has a beard. In the ibex the beard is not developed during the summer, and is so small at other times that it may be called rudimentary. (16. See Dr. Gray's 'Catalogue of Mammalia in the British Museum,' part iii. 1852, p. 144.) With some monkeys the beard is confined to the male, as in the orang; or is much larger in the male than in the female, as in the Mycetes caraya and Pithecia satanas (Fig. 68). So it is with the whiskers of some species of Macacus (17. Rengger, 'Säugethiere,' etc., s. 14; Desmarest, 'Mammalogie,' p. 86.), and, as we have seen, with the manes of some species of baboons. But with most kinds of monkeys the various tufts of hair about the face and head are alike in both sexes. The males of various members of the ox family (Bovidae), and of certain antelopes, are furnished with a dewlap, or great fold of skin on the neck, which is much less developed in the female. Now, what must we conclude with respect to such sexual differences as these? No one will pretend that the beards of certain male goats, or the dewlaps of the bull, or the crests of hair along the backs of certain male antelopes, are of any use to them in their ordinary habits. It is possible that the immense beard of the male Pithecia, and the large beard of the male orang, may protect their throats when fighting; for the keepers in the Zoological Gardens inform me that many monkeys attack each other by the throat; but it is not probable that the beard has been developed for a distinct purpose from that served by the whiskers, moustache, and other tufts of hair on the face; and no one will suppose that these are useful as a protection. Must we attribute all these appendages of hair or skin to mere purposeless variability in the male? It cannot be denied that this is possible; for in many domesticated quadrupeds, certain characters, apparently not derived through reversion from any wild parent form, are confined to the males, or are more developed in them than in the females--for instance, the hump on the male zebu-cattle of India, the tail of fat-tailed rams, the arched outline of the forehead in the males of several breeds of sheep, and lastly, the mane, the long hairs on the hind legs, and the dewlap of the male of the Berbura goat. (18. See the chapters on these several animals in vol. i. of my 'Variation of Animals under Domestication;' also vol. ii. p. 73; also chap. xx. on the practice of selection by semi-civilised people. For the Berbura goat, see Dr. Gray, 'Catalogue,' ibid. p. 157.) The mane, which occurs only in the rams of an African breed of sheep, is a true secondary sexual character, for, as I hear from Mr. Winwood Reade, it is not developed if the animal be castrated. Although we ought to be extremely cautious, as shewn in my work on 'Variation under Domestication,' in concluding that any character, even with animals kept by semi-civilised people, has not been subjected to selection by man, and thus augmented, yet in the cases just specified this is improbable; more especially as the characters are confined to the males, or are more strongly developed in them than in the females. If it were positively known that the above African ram is a descendant of the same primitive stock as the other breeds of sheep, and if the Berbura male-goat with his mane, dewlap, etc., is descended from the same stock as other goats, then, assuming that selection has not been applied to these characters, they must be due to simple variability, together with sexually-limited inheritance. Hence it appears reasonable to extend this same view to all analogous cases with animals in a state of nature. Nevertheless I cannot persuade myself that it generally holds good, as in the case of the extraordinary development of hair on the throat and fore-legs of the male Ammotragus, or in that of the immense beard of the male Pithecia. Such study as I have been able to give to nature makes me believe that parts or organs which are highly developed, were acquired at some period for a special purpose. With those antelopes in which the adult male is more strongly-coloured than the female, and with those monkeys in which the hair on the face is elegantly arranged and coloured in a diversified manner, it seems probable that the crests and tufts of hair were gained as ornaments; and this I know is the opinion of some naturalists. If this be correct, there can be little doubt that they were gained or at least modified through sexual selection; but how far the same view may be extended to other mammals is doubtful. COLOUR OF THE HAIR AND OF THE NAKED SKIN. I will first give briefly all the cases known to me of male quadrupeds differing in colour from the females. With Marsupials, as I am informed by Mr. Gould, the sexes rarely differ in this respect; but the great red kangaroo offers a striking exception, "delicate blue being the prevailing tint in those parts of the female which in the male are red." (19. Osphranter rufus, Gould, 'Mammals of Australia,' 1863, vol. ii. On the Didelphis, Desmarest, 'Mammalogie,' p. 256.) In the Didelphis opossum of Cayenne the female is said to be a little more red than the male. Of the Rodents, Dr. Gray remarks: "African squirrels, especially those found in the tropical regions, have the fur much brighter and more vivid at some seasons of the year than at others, and the fur of the male is generally brighter than that of the female." (20. 'Annals and Magazine of Natural History,' Nov. 1867, p. 325. On the Mus minutus, Desmarest, 'Mammalogie,' p. 304.) Dr. Gray informs me that he specified the African squirrels, because, from their unusually bright colours, they best exhibit this difference. The female of the Mus minutus of Russia is of a paler and dirtier tint than the male. In a large number of bats the fur of the male is lighter than in the female. (21. J.A. Allen, in 'Bulletin of Mus. Comp. Zoolog. of Cambridge, United States,' 1869, p. 207. Mr. Dobson on sexual characters in the Chiroptera, 'Proceedings of the Zoological Society,' 1873, p. 241. Dr. Gray on Sloths, ibid. 1871, p. 436.) Mr. Dobson also remarks, with respect to these animals: "Differences, depending partly or entirely on the possession by the male of fur of a much more brilliant hue, or distinguished by different markings or by the greater length of certain portions, are met only, to any appreciable extent, in the frugivorous bats in which the sense of sight is well developed." This last remark deserves attention, as bearing on the question whether bright colours are serviceable to male animals from being ornamental. In one genus of sloths, it is now established, as Dr. Gray states, "that the males are ornamented differently from the females--that is to say, that they have a patch of soft short hair between the shoulders, which is generally of a more or less orange colour, and in one species pure white. The females, on the contrary, are destitute of this mark." The terrestrial Carnivora and Insectivora rarely exhibit sexual differences of any kind, including colour. The ocelot (Felis pardalis), however, is exceptional, for the colours of the female, compared with those of the male, are "moins apparentes, le fauve, étant plus terne, le blanc moins pur, les raies ayant moins de largeur et les taches moins de diamètre." (22. Desmarest, 'Mammalogie,' 1820, p. 220. On Felis mitis, Rengger, ibid. s. 194.) The sexes of the allied Felis mitis also differ, but in a less degree; the general hues of the female being rather paler than in the male, with the spots less black. The marine Carnivora or seals, on the other hand, sometimes differ considerably in colour, and they present, as we have already seen, other remarkable sexual differences. Thus the male of the Otaria nigrescens of the southern hemisphere is of a rich brown shade above; whilst the female, who acquires her adult tints earlier in life than the male, is dark-grey above, the young of both sexes being of a deep chocolate colour. The male of the northern Phoca groenlandica is tawny grey, with a curious saddle-shaped dark mark on the back; the female is much smaller, and has a very different appearance, being "dull white or yellowish straw-colour, with a tawny hue on the back"; the young at first are pure white, and can "hardly be distinguished among the icy hummocks and snow, their colour thus acting as a protection." (23. Dr. Murie on the Otaria, 'Proceedings Zoological Society,' 1869, p. 108. Mr. R. Brown on the P. groenlandica, ibid. 1868, p. 417. See also on the colours of seals, Desmarest, ibid. pp. 243, 249.) With Ruminants sexual differences of colour occur more commonly than in any other order. A difference of this kind is general in the Strepsicerene antelopes; thus the male nilghau (Portax picta) is bluish-grey and much darker than the female, with the square white patch on the throat, the white marks on the fetlocks, and the black spots on the ears all much more distinct. We have seen that in this species the crests and tufts of hair are likewise more developed in the male than in the hornless female. I am informed by Mr. Blyth that the male, without shedding his hair, periodically becomes darker during the breeding-season. Young males cannot be distinguished from young females until about twelve months old; and if the male is emasculated before this period, he never, according to the same authority, changes colour. The importance of this latter fact, as evidence that the colouring of the Portax is of sexual origin, becomes obvious, when we hear (24. Judge Caton, in 'Transactions of the Ottawa Academy of Natural Sciences,' 1868, p. 4.) that neither the red summer-coat nor the blue winter-coat of the Virginian deer is at all affected by emasculation. With most or all of the highly-ornamented species of Tragelaphus the males are darker than the hornless females, and their crests of hair are more fully developed. In the male of that magnificent antelope, the Derbyan eland, the body is redder, the whole neck much blacker, and the white band which separates these colours broader than in the female. In the Cape eland, also, the male is slightly darker than the female. (25. Dr. Gray, 'Cat. of Mamm. in Brit. Mus.' part iii. 1852, pp. 134-142; also Dr. Gray, 'Gleanings from the Menagerie of Knowsley,' in which there is a splendid drawing of the Oreas derbianus: see the text on Tragelaphus. For the Cape eland (Oreas canna), see Andrew Smith, 'Zoology of S. Africa,' pl. 41 and 42. There are also many of these Antelopes in the Zoological Gardens.) In the Indian black-buck (A. bezoartica), which belongs to another tribe of antelopes, the male is very dark, almost black; whilst the hornless female is fawn-coloured. We meet in this species, as Mr. Blyth informs me, with an exactly similar series of facts, as in the Portax picta, namely, in the male periodically changing colour during the breeding-season, in the effects of emasculation on this change, and in the young of both sexes being indistinguishable from each other. In the Antilope niger the male is black, the female, as well as the young of both sexes, being brown; in A. sing-sing the male is much brighter coloured than the hornless female, and his chest and belly are blacker; in the male A. caama, the marks and lines which occur on various parts of the body are black, instead of brown as in the female; in the brindled gnu (A. gorgon) "the colours of the male are nearly the same as those of the female, only deeper and of a brighter hue." (26. On the Ant. niger, see 'Proc. Zool. Soc.' 1850, p. 133. With respect to an allied species, in which there is an equal sexual difference in colour, see Sir S. Baker, 'The Albert Nyanza,' 1866, vol. ii. p. 627. For the A. sing-sing, Gray, 'Cat. B. Mus.' p. 100. Desmarest, 'Mammalogie,' p. 468, on the A. caama. Andrew Smith, 'Zoology of S. Africa,' on the Gnu.) Other analogous cases could be added. The Banteng bull (Bos sondaicus) of the Malayan Archipelago is almost black, with white legs and buttocks; the cow is of a bright dun, as are the young males until about the age of three years, when they rapidly change colour. The emasculated bull reverts to the colour of the female. The female Kemas goat is paler, and both it and the female Capra aegagrus are said to be more uniformly tinted than their males. Deer rarely present any sexual differences in colour. Judge Caton, however, informs me that in the males of the wapiti deer (Cervus canadensis) the neck, belly, and legs are much darker than in the female; but during the winter the darker tints gradually fade away and disappear. I may here mention that Judge Caton has in his park three races of the Virginian deer, which differ slightly in colour, but the differences are almost exclusively confined to the blue winter or breeding-coat; so that this case may be compared with those given in a previous chapter of closely-allied or representative species of birds, which differ from each other only in their breeding plumage. (27. 'Ottawa Academy of Sciences,' May 21, 1868, pp. 3, 5.) The females of Cervus paludosus of S. America, as well as the young of both sexes, do not possess the black stripes on the nose and the blackish-brown line on the breast, which are characteristic of the adult males. (28. S. Muller, on the Banteng, 'Zoog. Indischen Archipel.' 1839-1844, tab. 35; see also Raffles, as quoted by Mr. Blyth, in 'Land and Water,' 1867, p. 476. On goats, Dr. Gray, 'Catalogue of the British Museum,' p. 146; Desmarest, 'Mammalogie,' p. 482. On the Cervus paludosus, Rengger, ibid. s. 345.) Lastly, as I am informed by Mr. Blyth, the mature male of the beautifully coloured and spotted axis deer is considerably darker than the female: and this hue the castrated male never acquires. The last Order which we need consider is that of the Primates. The male of the Lemur macaco is generally coal-black, whilst the female is brown. (29. Sclater, 'Proc. Zool. Soc.' 1866, p. i. The same fact has also been fully ascertained by MM. Pollen and van Dam. See, also, Dr. Gray in 'Annals and Magazine of Natural History,' May 1871, p. 340.) Of the Quadrumana of the New World, the females and young of Mycetes caraya are greyish-yellow and like each other; in the second year the young male becomes reddish-brown; in the third, black, excepting the stomach, which, however, becomes quite black in the fourth or fifth year. There is also a strongly-marked difference in colour between the sexes of Mycetes seniculus and Cebus capucinus; the young of the former, and I believe of the latter species, resembling the females. With Pithecia leucocephala the young likewise resemble the females, which are brownish-black above and light rusty-red beneath, the adult males being black. The ruff of hair round the face of Ateles marginatus is tinted yellow in the male and white in the female. Turning to the Old World, the males of Hylobates hoolock are always black, with the exception of a white band over the brows; the females vary from whity-brown to a dark tint mixed with black, but are never wholly black. (30. On Mycetes, Rengger, ibid. s. 14; and Brehm, 'Thierleben,' B. i. s. 96, 107. On Ateles Desmarest, 'Mammalogie,' p. 75. On Hylobates, Blyth, 'Land and Water,' 1867, p. 135. On the Semnopithecus, S. Muller, 'Zoog. Indischen Archipel.' tab. x.) In the beautiful Cercopithecus diana, the head of the adult male is of an intense black, whilst that of the female is dark grey; in the former the fur between the thighs is of an elegant fawn-colour, in the latter it is paler. In the beautiful and curious moustache monkey (Cercopithecus cephus) the only difference between the sexes is that the tail of the male is chestnut and that of the female grey; but Mr. Bartlett informs me that all the hues become more pronounced in the male when adult, whilst in the female they remain as they were during youth. According to the coloured figures given by Solomon Muller, the male of Semnopithecus chrysomelas is nearly black, the female being pale brown. In the Cercopithecus cynosurus and griseo-viridis one part of the body, which is confined to the male sex, is of the most brilliant blue or green, and contrasts strikingly with the naked skin on the hinder part of the body, which is vivid red. [Fig. 69. Head of male Mandrill (from Gervais, 'Hist. Nat. des Mammifères').] Lastly, in the baboon family, the adult male of Cynocephalus hamadryas differs from the female not only by his immense mane, but slightly in the colour of the hair and of the naked callosities. In the drill (C. leucophaeus) the females and young are much paler-coloured, with less green, than the adult males. No other member in the whole class of mammals is coloured in so extraordinary a manner as the adult male mandrill (C. mormon). The face at this age becomes of a fine blue, with the ridge and tip of the nose of the most brilliant red. According to some authors, the face is also marked with whitish stripes, and is shaded in parts with black, but the colours appear to be variable. On the forehead there is a crest of hair, and on the chin a yellow beard. "Toutes les parties supérieures de leurs cuisses et le grand espace nu de leurs fesses sont également colorés du rouge le plus vif, avec un mélange de bleu qui ne manque reellement pas d'élégance." (31. Gervais, 'Hist. Nat. des Mammifères,' 1854, p. 103. Figures are given of the skull of the male. Also Desmarest, 'Mammalogie,' p. 70. Geoffroy St.-Hilaire and F. Cuvier, 'Hist. Nat. des Mammifères,' 1824, tom. i.) When the animal is excited all the naked parts become much more vividly tinted. Several authors have used the strongest expressions in describing these resplendent colours, which they compare with those of the most brilliant birds. Another remarkable peculiarity is that when the great canine teeth are fully developed, immense protuberances of bone are formed on each cheek, which are deeply furrowed longitudinally, and the naked skin over them is brilliantly-coloured, as just-described. (Fig. 69.) In the adult females and in the young of both sexes these protuberances are scarcely perceptible; and the naked parts are much less bright coloured, the face being almost black, tinged with blue. In the adult female, however, the nose at certain regular intervals of time becomes tinted with red. In all the cases hitherto given the male is more strongly or brighter coloured than the female, and differs from the young of both sexes. But as with some few birds it is the female which is brighter coloured than the male, so with the Rhesus monkey (Macacus rhesus), the female has a large surface of naked skin round the tail, of a brilliant carmine red, which, as I was assured by the keepers in the Zoological Gardens, periodically becomes even yet more vivid, and her face also is pale red. On the other hand, in the adult male and in the young of both sexes (as I saw in the Gardens), neither the naked skin at the posterior end of the body, nor the face, shew a trace of red. It appears, however, from some published accounts, that the male does occasionally, or during certain seasons, exhibit some traces of the red. Although he is thus less ornamented than the female, yet in the larger size of his body, larger canine teeth, more developed whiskers, more prominent superciliary ridges, he follows the common rule of the male excelling the female. I have now given all the cases known to me of a difference in colour between the sexes of mammals. Some of these may be the result of variations confined to one sex and transmitted to the same sex, without any good being gained, and therefore without the aid of selection. We have instances of this with our domesticated animals, as in the males of certain cats being rusty-red, whilst the females are tortoise-shell coloured. Analogous cases occur in nature: Mr. Bartlett has seen many black varieties of the jaguar, leopard, vulpine phalanger, and wombat; and he is certain that all, or nearly all these animals, were males. On the other hand, with wolves, foxes, and apparently American squirrels, both sexes are occasionally born black. Hence it is quite possible that with some mammals a difference in colour between the sexes, especially when this is congenital, may simply be the result, without the aid of selection, of the occurrence of one or more variations, which from the first were sexually limited in their transmission. Nevertheless it is improbable that the diversified, vivid, and contrasted colours of certain quadrupeds, for instance, of the above monkeys and antelopes, can thus be accounted for. We should bear in mind that these colours do not appear in the male at birth, but only at or near maturity; and that unlike ordinary variations, they are lost if the male be emasculated. It is on the whole probable that the strongly-marked colours and other ornamental characters of male quadrupeds are beneficial to them in their rivalry with other males, and have consequently been acquired through sexual selection. This view is strengthened by the differences in colour between the sexes occurring almost exclusively, as may be collected from the previous details, in those groups and sub-groups of mammals which present other and strongly-marked secondary sexual characters; these being likewise due to sexual selection. Quadrupeds manifestly take notice of colour. Sir S. Baker repeatedly observed that the African elephant and rhinoceros attacked white or grey horses with special fury. I have elsewhere shewn (32. The 'Variation of Animals and Plants under Domestication,' 1868, vol. ii. pp. 102, 103.) that half-wild horses apparently prefer to pair with those of the same colour, and that herds of fallow-deer of different colours, though living together, have long kept distinct. It is a more significant fact that a female zebra would not admit the addresses of a male ass until he was painted so as to resemble a zebra, and then, as John Hunter remarks, "she received him very readily. In this curious fact, we have instinct excited by mere colour, which had so strong an effect as to get the better of everything else. But the male did not require this, the female being an animal somewhat similar to himself, was sufficient to rouse him." (33. 'Essays and Observations,' by J. Hunter, edited by Owen, 1861, vol. i. p. 194.) In an earlier chapter we have seen that the mental powers of the higher animals do not differ in kind, though greatly in degree, from the corresponding powers of man, especially of the lower and barbarous races; and it would appear that even their taste for the beautiful is not widely different from that of the Quadrumana. As the negro of Africa raises the flesh on his face into parallel ridges "or cicatrices, high above the natural surface, which unsightly deformities are considered great personal attractions" (34. Sir S. Baker, 'The Nile Tributaries of Abyssinia,' 1867.);--as negroes and savages in many parts of the world paint their faces with red, blue, white, or black bars,--so the male mandrill of Africa appears to have acquired his deeply-furrowed and gaudily-coloured face from having been thus rendered attractive to the female. No doubt it is to us a most grotesque notion that the posterior end of the body should be coloured for the sake of ornament even more brilliantly than the face; but this is not more strange than that the tails of many birds should be especially decorated. With mammals we do not at present possess any evidence that the males take pains to display their charms before the female; and the elaborate manner in which this is performed by male birds and other animals is the strongest argument in favour of the belief that the females admire, or are excited by, the ornaments and colours displayed before them. There is, however, a striking parallelism between mammals and birds in all their secondary sexual characters, namely in their weapons for fighting with rival males, in their ornamental appendages, and in their colours. In both classes, when the male differs from the female, the young of both sexes almost always resemble each other, and in a large majority of cases resemble the adult female. In both classes the male assumes the characters proper to his sex shortly before the age of reproduction; and if emasculated at an early period, loses them. In both classes the change of colour is sometimes seasonal, and the tints of the naked parts sometimes become more vivid during the act of courtship. In both classes the male is almost always more vividly or strongly coloured than the female, and is ornamented with larger crests of hair or feathers, or other such appendages. In a few exceptional cases the female in both classes is more highly ornamented than the male. With many mammals, and at least in the case of one bird, the male is more odoriferous than the female. In both classes the voice of the male is more powerful than that of the female. Considering this parallelism, there can be little doubt that the same cause, whatever it may be, has acted on mammals and birds; and the result, as far as ornamental characters are concerned, may be attributed, as it appears to me, to the long-continued preference of the individuals of one sex for certain individuals of the opposite sex, combined with their success in leaving a larger number of offspring to inherit their superior attractions. EQUAL TRANSMISSION OF ORNAMENTAL CHARACTERS TO BOTH SEXES. With many birds, ornaments, which analogy leads us to believe were primarily acquired by the males, have been transmitted equally, or almost equally, to both sexes; and we may now enquire how far this view applies to mammals. With a considerable number of species, especially of the smaller kinds, both sexes have been coloured, independently of sexual selection, for the sake of protection; but not, as far as I can judge, in so many cases, nor in so striking a manner, as in most of the lower classes. Audubon remarks that he often mistook the musk-rat (35. Fiber zibethicus, Audubon and Bachman, 'The Quadrupeds of North America,' 1846, p. 109.), whilst sitting on the banks of a muddy stream, for a clod of earth, so complete was the resemblance. The hare on her form is a familiar instance of concealment through colour; yet this principle partly fails in a closely-allied species, the rabbit, for when running to its burrow, it is made conspicuous to the sportsman, and no doubt to all beasts of prey, by its upturned white tail. No one doubts that the quadrupeds inhabiting snow-clad regions have been rendered white to protect them from their enemies, or to favour their stealing on their prey. In regions where snow never lies for long, a white coat would be injurious; consequently, species of this colour are extremely rare in the hotter parts of the world. It deserves notice that many quadrupeds inhabiting moderately cold regions, although they do not assume a white winter dress, become paler during this season; and this apparently is the direct result of the conditions to which they have long been exposed. Pallas (36. 'Novae species Quadrupedum e Glirium ordine,' 1778, p. 7. What I have called the roe is the Capreolus sibiricus subecaudatus of Pallas.) states that in Siberia a change of this nature occurs with the wolf, two species of Mustela, the domestic horse, the Equus hemionus, the domestic cow, two species of antelopes, the musk-deer, the roe, elk, and reindeer. The roe, for instance, has a red summer and a greyish-white winter coat; and the latter may perhaps serve as a protection to the animal whilst wandering through the leafless thickets, sprinkled with snow and hoar-frost. If the above-named animals were gradually to extend their range into regions perpetually covered with snow, their pale winter-coats would probably be rendered through natural selection, whiter and whiter, until they became as white as snow. Mr. Reeks has given me a curious instance of an animal profiting by being peculiarly coloured. He raised from fifty to sixty white and brown piebald rabbits in a large walled orchard; and he had at the same time some similarly coloured cats in his house. Such cats, as I have often noticed, are very conspicuous during day; but as they used to lie in watch during the dusk at the mouths of the burrows, the rabbits apparently did not distinguish them from their parti-coloured brethren. The result was that, within eighteen months, every one of these parti-coloured rabbits was destroyed; and there was evidence that this was effected by the cats. Colour seems to be advantageous to another animal, the skunk, in a manner of which we have had many instances in other classes. No animal will voluntarily attack one of these creatures on account of the dreadful odour which it emits when irritated; but during the dusk it would not easily be recognised and might be attacked by a beast of prey. Hence it is, as Mr. Belt believes (37. 'The Naturalist in Nicaragua,' p. 249.), that the skunk is provided with a great white bushy tail, which serves as a conspicuous warning. [Fig. 70. Tragelaphus scriptus, male (from the Knowsley Menagerie). Fig. 71. Damalis pygarga, male (from the Knowsley Menagerie).] Although we must admit that many quadrupeds have received their present tints either as a protection, or as an aid in procuring prey, yet with a host of species, the colours are far too conspicuous and too singularly arranged to allow us to suppose that they serve for these purposes. We may take as an illustration certain antelopes; when we see the square white patch on the throat, the white marks on the fetlocks, and the round black spots on the ears, all more distinct in the male of the Portax picta, than in the female;--when we see that the colours are more vivid, that the narrow white lines on the flank and the broad white bar on the shoulder are more distinct in the male Oreas derbyanus than in the female;--when we see a similar difference between the sexes of the curiously-ornamented Tragelaphus scriptus (Fig. 70),--we cannot believe that differences of this kind are of any service to either sex in their daily habits of life. It seems a much more probable conclusion that the various marks were first acquired by the males and their colours intensified through sexual selection, and then partially transferred to the females. If this view be admitted, there can be little doubt that the equally singular colours and marks of many other antelopes, though common to both sexes, have been gained and transmitted in a like manner. Both sexes, for instance, of the koodoo (Strepsiceros kudu) (Fig. 64) have narrow white vertical lines on their hind flanks, and an elegant angular white mark on their foreheads. Both sexes in the genus Damalis are very oddly coloured; in D. pygarga the back and neck are purplish-red, shading on the flanks into black; and these colours are abruptly separated from the white belly and from a large white space on the buttocks; the head is still more oddly coloured, a large oblong white mask, narrowly-edged with black, covers the face up to the eyes (Fig. 71); there are three white stripes on the forehead, and the ears are marked with white. The fawns of this species are of a uniform pale yellowish-brown. In Damalis albifrons the colouring of the head differs from that in the last species in a single white stripe replacing the three stripes, and in the ears being almost wholly white. (38. See the fine plates in A. Smith's 'Zoology of South Africa,' and Dr. Gray's 'Gleanings from the Menagerie of Knowsley.') After having studied to the best of my ability the sexual differences of animals belonging to all classes, I cannot avoid the conclusion that the curiously-arranged colours of many antelopes, though common to both sexes, are the result of sexual selection primarily applied to the male. The same conclusion may perhaps be extended to the tiger, one of the most beautiful animals in the world, the sexes of which cannot be distinguished by colour, even by the dealers in wild beasts. Mr. Wallace believes (39. 'Westminster Review,' July 1, 1867, p. 5.) that the striped coat of the tiger "so assimilates with the vertical stems of the bamboo, as to assist greatly in concealing him from his approaching prey." But this view does not appear to me satisfactory. We have some slight evidence that his beauty may be due to sexual selection, for in two species of Felis the analogous marks and colours are rather brighter in the male than in the female. The zebra is conspicuously striped, and stripes cannot afford any protection in the open plains of South Africa. Burchell (40. 'Travels in South Africa,' 1824, vol. ii. p. 315.) in describing a herd says, "their sleek ribs glistened in the sun, and the brightness and regularity of their striped coats presented a picture of extraordinary beauty, in which probably they are not surpassed by any other quadruped." But as throughout the whole group of the Equidae the sexes are identical in colour, we have here no evidence of sexual selection. Nevertheless he who attributes the white and dark vertical stripes on the flanks of various antelopes to this process, will probably extend the same view to the Royal Tiger and beautiful Zebra. We have seen in a former chapter that when young animals belonging to any class follow nearly the same habits of life as their parents, and yet are coloured in a different manner, it may be inferred that they have retained the colouring of some ancient and extinct progenitor. In the family of pigs, and in the tapirs, the young are marked with longitudinal stripes, and thus differ from all the existing adult species in these two groups. With many kinds of deer the young are marked with elegant white spots, of which their parents exhibit not a trace. A graduated series can be followed from the axis deer, both sexes of which at all ages and during all seasons are beautifully spotted (the male being rather more strongly coloured than the female), to species in which neither the old nor the young are spotted. I will specify some of the steps in this series. The Mantchurian deer (Cervus mantchuricus) is spotted during the whole year, but, as I have seen in the Zoological Gardens, the spots are much plainer during the summer, when the general colour of the coat is lighter, than during the winter, when the general colour is darker and the horns are fully developed. In the hog-deer (Hyelaphus porcinus) the spots are extremely conspicuous during the summer when the coat is reddish-brown, but quite disappear during the winter when the coat is brown. (41. Dr. Gray, 'Gleanings from the Menagerie of Knowsley,' p. 64. Mr. Blyth, in speaking ('Land and Water,' 1869, p. 42) of the hog-deer of Ceylon, says it is more brightly spotted with white than the common hog-deer, at the season when it renews its horns.) In both these species the young are spotted. In the Virginian deer the young are likewise spotted, and about five per cent. of the adult animals living in Judge Caton's park, as I am informed by him, temporarily exhibit at the period when the red summer coat is being replaced by the bluish winter coat, a row of spots on each flank, which are always the same in number, though very variable in distinctness. From this condition there is but a very small step to the complete absence of spots in the adults at all seasons; and, lastly, to their absence at all ages and seasons, as occurs with certain species. From the existence of this perfect series, and more especially from the fawns of so many species being spotted, we may conclude that the now living members of the deer family are the descendants of some ancient species which, like the axis deer, was spotted at all ages and seasons. A still more ancient progenitor probably somewhat resembled the Hyomoschus aquaticus--for this animal is spotted, and the hornless males have large exserted canine teeth, of which some few true deer still retain rudiments. Hyomoschus, also, offers one of those interesting cases of a form linking together two groups, for it is intermediate in certain osteological characters between the pachyderms and ruminants, which were formerly thought to be quite distinct. (42. Falconer and Cautley, 'Proc. Geolog. Soc.' 1843; and Falconer's 'Pal. Memoirs,' vol. i. p. 196.) A curious difficulty here arises. If we admit that coloured spots and stripes were first acquired as ornaments, how comes it that so many existing deer, the descendants of an aboriginally spotted animal, and all the species of pigs and tapirs, the descendants of an aboriginally striped animal, have lost in their adult state their former ornaments? I cannot satisfactorily answer this question. We may feel almost sure that the spots and stripes disappeared at or near maturity in the progenitors of our existing species, so that they were still retained by the young; and, owing to the law of inheritance at corresponding ages, were transmitted to the young of all succeeding generations. It may have been a great advantage to the lion and puma, from the open nature of their usual haunts, to have lost their stripes, and to have been thus rendered less conspicuous to their prey; and if the successive variations, by which this end was gained, occurred rather late in life, the young would have retained their stripes, as is now the case. As to deer, pigs, and tapirs, Fritz Müller has suggested to me that these animals, by the removal of their spots or stripes through natural selection, would have been less easily seen by their enemies; and that they would have especially required this protection, as soon as the carnivora increased in size and number during the tertiary periods. This may be the true explanation, but it is rather strange that the young should not have been thus protected, and still more so that the adults of some species should have retained their spots, either partially or completely, during part of the year. We know that, when the domestic ass varies and becomes reddish-brown, grey, or black, the stripes on the shoulders and even on the spine frequently disappear, though we cannot explain the cause. Very few horses, except dun-coloured kinds, have stripes on any part of their bodies, yet we have good reason to believe that the aboriginal horse was striped on the legs and spine, and probably on the shoulders. (43. The 'Variation of Animals and Plants under Domestication,' 1868, vol. i. pp. 61-64.) Hence the disappearance of the spots and stripes in our adult existing deer, pigs, and tapirs, may be due to a change in the general colour of their coats; but whether this change was effected through sexual or natural selection, or was due to the direct action of the conditions of life, or to some other unknown cause, it is impossible to decide. An observation made by Mr. Sclater well illustrates our ignorance of the laws which regulate the appearance and disappearance of stripes; the species of Asinus which inhabit the Asiatic continent are destitute of stripes, not having even the cross shoulder-stripe, whilst those which inhabit Africa are conspicuously striped, with the partial exception of A. taeniopus, which has only the cross shoulder-stripe and generally some faint bars on the legs; and this species inhabits the almost intermediate region of Upper Egypt and Abyssinia. (44. 'Proc. Zool. Soc.' 1862, p. 164. See, also, Dr. Hartmann, 'Ann. d. Landw.' Bd. xliii. s. 222.) QUADRUMANA. [Fig. 72. Head of Semnopithecus rubicundus. This and the following figures (from Prof. Gervais) are given to shew the odd arrangement and development of the hair on the head. Fig. 73. Head of Semnopithecus comatus. Fig. 74. Head of Cebus capucinus. Fig. 75. Head of Ateles marginatus. Fig. 76. Head of Cebus vellerosus.] Before we conclude, it will be well to add a few remarks on the ornaments of monkeys. In most of the species the sexes resemble each other in colour, but in some, as we have seen, the males differ from the females, especially in the colour of the naked parts of the skin, in the development of the beard, whiskers, and mane. Many species are coloured either in so extraordinary or so beautiful a manner, and are furnished with such curious and elegant crests of hair, that we can hardly avoid looking at these characters as having been gained for the sake of ornament. The accompanying figures (Figs. 72 to 76) serve to shew the arrangement of the hair on the face and head in several species. It is scarcely conceivable that these crests of hair, and the strongly contrasted colours of the fur and skin, can be the result of mere variability without the aid of selection; and it is inconceivable that they can be of use in any ordinary way to these animals. If so, they have probably been gained through sexual selection, though transmitted equally, or almost equally, to both sexes. With many of the Quadrumana, we have additional evidence of the action of sexual selection in the greater size and strength of the males, and in the greater development of their canine teeth, in comparison with the females. [Fig. 77. Cercopithecus petaurista (from Brehm).] A few instances will suffice of the strange manner in which both sexes of some species are coloured, and of the beauty of others. The face of the Cercopithecus petaurista (Fig. 77) is black, the whiskers and beard being white, with a defined, round, white spot on the nose, covered with short white hair, which gives to the animal an almost ludicrous aspect. The Semnopithecus frontatus likewise has a blackish face with a long black beard, and a large naked spot on the forehead of a bluish-white colour. The face of Macacus lasiotus is dirty flesh-coloured, with a defined red spot on each cheek. The appearance of Cercocebus aethiops is grotesque, with its black face, white whiskers and collar, chestnut head, and a large naked white spot over each eyelid. In very many species, the beard, whiskers, and crests of hair round the face are of a different colour from the rest of the head, and when different, are always of a lighter tint (45. I observed this fact in the Zoological Gardens; and many cases may be seen in the coloured plates in Geoffroy St.-Hilaire and F. Cuvier, 'Histoire Nat. des Mammifères,' tom. i. 1824.), being often pure white, sometimes bright yellow, or reddish. The whole face of the South American Brachyurus calvus is of a "glowing scarlet hue"; but this colour does not appear until the animal is nearly mature. (46. Bates, 'The Naturalist on the Amazons,' 1863, vol. ii. p. 310.) The naked skin of the face differs wonderfully in colour in the various species. It is often brown or flesh-colour, with parts perfectly white, and often as black as that of the most sooty negro. In the Brachyurus the scarlet tint is brighter than that of the most blushing Caucasian damsel. It is sometimes more distinctly orange than in any Mongolian, and in several species it is blue, passing into violet or grey. In all the species known to Mr. Bartlett, in which the adults of both sexes have strongly-coloured faces, the colours are dull or absent during early youth. This likewise holds good with the mandrill and Rhesus, in which the face and the posterior parts of the body are brilliantly coloured in one sex alone. In these latter cases we have reason to believe that the colours were acquired through sexual selection; and we are naturally led to extend the same view to the foregoing species, though both sexes when adult have their faces coloured in the same manner. [Fig. 78. Cercopithecus diana (from Brehm).] Although many kinds of monkeys are far from beautiful according to our taste, other species are universally admired for their elegant appearance and bright colours. The Semnopithecus nemaeus, though peculiarly coloured, is described as extremely pretty; the orange-tinted face is surrounded by long whiskers of glossy whiteness, with a line of chestnut-red over the eyebrows; the fur on the back is of a delicate grey, with a square patch on the loins, the tail and the fore-arms being of a pure white; a gorget of chestnut surmounts the chest; the thighs are black, with the legs chestnut-red. I will mention only two other monkeys for their beauty; and I have selected these as presenting slight sexual differences in colour, which renders it in some degree probable that both sexes owe their elegant appearance to sexual selection. In the moustache-monkey (Cercopithecus cephus) the general colour of the fur is mottled-greenish with the throat white; in the male the end of the tail is chestnut, but the face is the most ornamented part, the skin being chiefly bluish-grey, shading into a blackish tint beneath the eyes, with the upper lip of a delicate blue, clothed on the lower edge with a thin black moustache; the whiskers are orange-coloured, with the upper part black, forming a band which extends backwards to the ears, the latter being clothed with whitish hairs. In the Zoological Society's Gardens I have often overheard visitors admiring the beauty of another monkey, deservedly called Cercopithecus diana (Fig. 78); the general colour of the fur is grey; the chest and inner surface of the forelegs are white; a large triangular defined space on the hinder part of the back is rich chestnut; in the male the inner sides of the thighs and the abdomen are delicate fawn-coloured, and the top of the head is black; the face and ears are intensely black, contrasting finely with a white transverse crest over the eyebrows and a long white peaked beard, of which the basal portion is black. (47. I have seen most of the above monkeys in the Zoological Society's Gardens. The description of the Semnopithecus nemaeus is taken from Mr. W.C. Martin's 'Natural History of Mammalia,' 1841, p. 460; see also pp. 475, 523.) In these and many other monkeys, the beauty and singular arrangement of their colours, and still more the diversified and elegant arrangement of the crests and tufts of hair on their heads, force the conviction on my mind that these characters have been acquired through sexual selection exclusively as ornaments. SUMMARY. The law of battle for the possession of the female appears to prevail throughout the whole great class of mammals. Most naturalists will admit that the greater size, strength, courage, and pugnacity of the male, his special weapons of offence, as well as his special means of defence, have been acquired or modified through that form of selection which I have called sexual. This does not depend on any superiority in the general struggle for life, but on certain individuals of one sex, generally the male, being successful in conquering other males, and leaving a larger number of offspring to inherit their superiority than do the less successful males. There is another and more peaceful kind of contest, in which the males endeavour to excite or allure the females by various charms. This is probably carried on in some cases by the powerful odours emitted by the males during the breeding-season; the odoriferous glands having been acquired through sexual selection. Whether the same view can be extended to the voice is doubtful, for the vocal organs of the males must have been strengthened by use during maturity, under the powerful excitements of love, jealousy or rage, and will consequently have been transmitted to the same sex. Various crests, tufts, and mantles of hair, which are either confined to the male, or are more developed in this sex than in the female, seem in most cases to be merely ornamental, though they sometimes serve as a defence against rival males. There is even reason to suspect that the branching horns of stags, and the elegant horns of certain antelopes, though properly serving as weapons of offence or defence, have been partly modified for ornament. When the male differs in colour from the female, he generally exhibits darker and more strongly-contrasted tints. We do not in this class meet with the splendid red, blue, yellow, and green tints, so common with male birds and many other animals. The naked parts, however, of certain Quadrumana must be excepted; for such parts, often oddly situated, are brilliantly coloured in some species. The colours of the male in other cases may be due to simple variation, without the aid of selection. But when the colours are diversified and strongly pronounced, when they are not developed until near maturity, and when they are lost after emasculation, we can hardly avoid the conclusion that they have been acquired through sexual selection for the sake of ornament, and have been transmitted exclusively, or almost exclusively, to the same sex. When both sexes are coloured in the same manner, and the colours are conspicuous or curiously arranged, without being of the least apparent use as a protection, and especially when they are associated with various other ornamental appendages, we are led by analogy to the same conclusion, namely, that they have been acquired through sexual selection, although transmitted to both sexes. That conspicuous and diversified colours, whether confined to the males or common to both sexes, are as a general rule associated in the same groups and sub-groups with other secondary sexual characters serving for war or for ornament, will be found to hold good, if we look back to the various cases given in this and the last chapter. The law of the equal transmission of characters to both sexes, as far as colour and other ornaments are concerned, has prevailed far more extensively with mammals than with birds; but weapons, such as horns and tusks, have often been transmitted either exclusively or much more perfectly to the males than to the females. This is surprising, for, as the males generally use their weapons for defence against enemies of all kinds, their weapons would have been of service to the females. As far as we can see, their absence in this sex can be accounted for only by the form of inheritance which has prevailed. Finally, with quadrupeds the contest between the individuals of the same sex, whether peaceful or bloody, has, with the rarest exceptions, been confined to the males; so that the latter have been modified through sexual selection, far more commonly than the females, either for fighting with each other or for alluring the opposite sex. PART III. SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION. CHAPTER XIX. SECONDARY SEXUAL CHARACTERS OF MAN. Differences between man and woman--Causes of such differences and of certain characters common to both sexes--Law of battle--Differences in mental powers, and voice--On the influence of beauty in determining the marriages of mankind--Attention paid by savages to ornaments--Their ideas of beauty in woman--The tendency to exaggerate each natural peculiarity. With mankind the differences between the sexes are greater than in most of the Quadrumana, but not so great as in some, for instance, the mandrill. Man on an average is considerably taller, heavier, and stronger than woman, with squarer shoulders and more plainly-pronounced muscles. Owing to the relation which exists between muscular development and the projection of the brows (1. Schaaffhausen, translation in 'Anthropological Review,' Oct. 1868, pp. 419, 420, 427.), the superciliary ridge is generally more marked in man than in woman. His body, and especially his face, is more hairy, and his voice has a different and more powerful tone. In certain races the women are said to differ slightly in tint from the men. For instance, Schweinfurth, in speaking of a negress belonging to the Monbuttoos, who inhabit the interior of Africa a few degrees north of the equator, says, "Like all her race, she had a skin several shades lighter than her husband's, being something of the colour of half-roasted coffee." (2. 'The Heart of Africa,' English transl. 1873, vol i. p. 544.) As the women labour in the fields and are quite unclothed, it is not likely that they differ in colour from the men owing to less exposure to the weather. European women are perhaps the brighter coloured of the two sexes, as may be seen when both have been equally exposed. Man is more courageous, pugnacious and energetic than woman, and has a more inventive genius. His brain is absolutely larger, but whether or not proportionately to his larger body, has not, I believe, been fully ascertained. In woman the face is rounder; the jaws and the base of the skull smaller; the outlines of the body rounder, in parts more prominent; and her pelvis is broader than in man (3. Ecker, translation, in 'Anthropological Review,' Oct. 1868, pp. 351-356. The comparison of the form of the skull in men and women has been followed out with much care by Welcker.); but this latter character may perhaps be considered rather as a primary than a secondary sexual character. She comes to maturity at an earlier age than man. As with animals of all classes, so with man, the distinctive characters of the male sex are not fully developed until he is nearly mature; and if emasculated they never appear. The beard, for instance, is a secondary sexual character, and male children are beardless, though at an early age they have abundant hair on the head. It is probably due to the rather late appearance in life of the successive variations whereby man has acquired his masculine characters, that they are transmitted to the male sex alone. Male and female children resemble each other closely, like the young of so many other animals in which the adult sexes differ widely; they likewise resemble the mature female much more closely than the mature male. The female, however, ultimately assumes certain distinctive characters, and in the formation of her skull, is said to be intermediate between the child and the man. (4. Ecker and Welcker, ibid. pp. 352, 355; Vogt, 'Lectures on Man,' Eng. translat. p. 81.) Again, as the young of closely allied though distinct species do not differ nearly so much from each other as do the adults, so it is with the children of the different races of man. Some have even maintained that race-differences cannot be detected in the infantile skull. (5. Schaaffhausen, 'Anthropolog. Review,' ibid. p. 429.) In regard to colour, the new-born negro child is reddish nut-brown, which soon becomes slaty-grey; the black colour being fully developed within a year in the Soudan, but not until three years in Egypt. The eyes of the negro are at first blue, and the hair chestnut-brown rather than black, being curled only at the ends. The children of the Australians immediately after birth are yellowish-brown, and become dark at a later age. Those of the Guaranys of Paraguay are whitish-yellow, but they acquire in the course of a few weeks the yellowish-brown tint of their parents. Similar observations have been made in other parts of America. (6. Pruner-Bey, on negro infants as quoted by Vogt, 'Lectures on Man,' Eng. translat. 1864, p. 189: for further facts on negro infants, as quoted from Winterbottom and Camper, see Lawrence, 'Lectures on Physiology,' etc. 1822, p. 451. For the infants of the Guaranys, see Rengger, 'Säugethiere,' etc. s. 3. See also Godron, 'De l'Espèce,' tom. ii. 1859, p. 253. For the Australians, Waitz, 'Introduction to Anthropology,' Eng. translat. 1863, p. 99.) I have specified the foregoing differences between the male and female sex in mankind, because they are curiously like those of the Quadrumana. With these animals the female is mature at an earlier age than the male; at least this is certainly the case in Cebus azarae. (7. Rengger, 'Säugethiere,' etc., 1830, s. 49.) The males of most species are larger and stronger than the females, of which fact the gorilla affords a well-known instance. Even in so trifling a character as the greater prominence of the superciliary ridge, the males of certain monkeys differ from the females (8. As in Macacus cynomolgus (Desmarest, 'Mammalogie,' p. 65), and in Hylobates agilis (Geoffroy St.-Hilaire and F. Cuvier, 'Histoire Nat. des Mammifères,' 1824, tom. i. p. 2)., and agree in this respect with mankind. In the gorilla and certain other monkeys, the cranium of the adult male presents a strongly-marked sagittal crest, which is absent in the female; and Ecker found a trace of a similar difference between the two sexes in the Australians. (9. 'Anthropological Review,' Oct. 1868, p. 353.) With monkeys when there is any difference in the voice, that of the male is the more powerful. We have seen that certain male monkeys have a well-developed beard, which is quite deficient, or much less developed in the female. No instance is known of the beard, whiskers, or moustache being larger in the female than in the male monkey. Even in the colour of the beard there is a curious parallelism between man and the Quadrumana, for with man when the beard differs in colour from the hair of the head, as is commonly the case, it is, I believe, almost always of a lighter tint, being often reddish. I have repeatedly observed this fact in England; but two gentlemen have lately written to me, saying that they form an exception to the rule. One of these gentlemen accounts for the fact by the wide difference in colour of the hair on the paternal and maternal sides of his family. Both had been long aware of this peculiarity (one of them having often been accused of dyeing his beard), and had been thus led to observe other men, and were convinced that the exceptions were very rare. Dr. Hooker attended to this little point for me in Russia, and found no exception to the rule. In Calcutta, Mr. J. Scott, of the Botanic Gardens, was so kind as to observe the many races of men to be seen there, as well as in some other parts of India, namely, two races of Sikhim, the Bhoteas, Hindoos, Burmese, and Chinese, most of which races have very little hair on the face; and he always found that when there was any difference in colour between the hair of the head and the beard, the latter was invariably lighter. Now with monkeys, as has already been stated, the beard frequently differs strikingly in colour from the hair of the head, and in such cases it is always of a lighter hue, being often pure white, sometimes yellow or reddish. (10. Mr. Blyth informs me that he has only seen one instance of the beard, whiskers, etc., in a monkey becoming white with old age, as is so commonly the case with us. This, however, occurred in an aged Macacus cynomolgus, kept in confinement whose moustaches were "remarkably long and human-like." Altogether this old monkey presented a ludicrous resemblance to one of the reigning monarchs of Europe, after whom he was universally nick-named. In certain races of man the hair on the head hardly ever becomes grey; thus Mr. D. Forbes has never, as he informs me, seen an instance with the Aymaras and Quichuas of South America.) In regard to the general hairiness of the body, the women in all races are less hairy than the men; and in some few Quadrumana the under side of the body of the female is less hairy than that of the male. (11. This is the case with the females of several species of Hylobates; see Geoffroy St.-Hilaire and F. Cuvier, 'Hist. Nat. des Mamm.' tom. i. See also, on H. lar, 'Penny Cyclopedia,' vol. ii. pp. 149, 150.) Lastly, male monkeys, like men, are bolder and fiercer than the females. They lead the troop, and when there is danger, come to the front. We thus see how close is the parallelism between the sexual differences of man and the Quadrumana. With some few species, however, as with certain baboons, the orang and the gorilla, there is a considerably greater difference between the sexes, as in the size of the canine teeth, in the development and colour of the hair, and especially in the colour of the naked parts of the skin, than in mankind. All the secondary sexual characters of man are highly variable, even within the limits of the same race; and they differ much in the several races. These two rules hold good generally throughout the animal kingdom. In the excellent observations made on board the Novara (12. The results were deduced by Dr. Weisbach from the measurements made by Drs. K. Scherzer and Schwarz, see 'Reise der Novara: Anthropolog. Theil,' 1867, ss. 216, 231, 234, 236, 239, 269.), the male Australians were found to exceed the females by only 65 millim. in height, whilst with the Javans the average excess was 218 millim.; so that in this latter race the difference in height between the sexes is more than thrice as great as with the Australians. Numerous measurements were carefully made of the stature, the circumference of the neck and chest, the length of the back-bone and of the arms, in various races; and nearly all these measurements shew that the males differ much more from one another than do the females. This fact indicates that, as far as these characters are concerned, it is the male which has been chiefly modified, since the several races diverged from their common stock. The development of the beard and the hairiness of the body differ remarkably in the men of distinct races, and even in different tribes or families of the same race. We Europeans see this amongst ourselves. In the Island of St. Kilda, according to Martin (13. 'Voyage to St. Kilda' (3rd ed. 1753), p. 37.), the men do not acquire beards until the age of thirty or upwards, and even then the beards are very thin. On the Europaeo-Asiatic continent, beards prevail until we pass beyond India; though with the natives of Ceylon they are often absent, as was noticed in ancient times by Diodorus. (14. Sir J.E. Tennent, 'Ceylon,' vol. ii. 1859, p. 107.) Eastward of India beards disappear, as with the Siamese, Malays, Kalmucks, Chinese, and Japanese; nevertheless, the Ainos (15. Quatrefages, 'Revue des Cours Scientifiques,' Aug. 29, 1868, p. 630; Vogt, 'Lectures on Man,' Eng. trans. p. 127.), who inhabit the northernmost islands of the Japan Archipelago, are the hairiest men in the world. With negroes the beard is scanty or wanting, and they rarely have whiskers; in both sexes the body is frequently almost destitute of fine down. (16. On the beards of negroes, Vogt, 'Lectures,' etc. p. 127; Waitz, 'Introduct. to Anthropology,' Engl. translat. 1863, vol. i. p. 96. It is remarkable that in the United States ('Investigations in Military and Anthropological Statistics of American Soldiers,' 1869, p. 569) the pure negroes and their crossed offspring seem to have bodies almost as hairy as Europeans.) On the other hand, the Papuans of the Malay Archipelago, who are nearly as black as negroes, possess well-developed beards. (17. Wallace, 'The Malay Arch.' vol. ii. 1869, p. 178.) In the Pacific Ocean the inhabitants of the Fiji Archipelago have large bushy beards, whilst those of the not distant archipelagoes of Tonga and Samoa are beardless; but these men belong to distinct races. In the Ellice group all the inhabitants belong to the same race; yet on one island alone, namely Nunemaya, "the men have splendid beards"; whilst on the other islands "they have, as a rule, a dozen straggling hairs for a beard." (18. Dr. J. Barnard Davis on Oceanic Races, in 'Anthropological Review,' April 1870, pp. 185, 191.) Throughout the great American continent the men may be said to be beardless; but in almost all the tribes a few short hairs are apt to appear on the face, especially in old age. With the tribes of North America, Catlin estimates that eighteen out of twenty men are completely destitute by nature of a beard; but occasionally there may be seen a man, who has neglected to pluck out the hairs at puberty, with a soft beard an inch or two in length. The Guaranys of Paraguay differ from all the surrounding tribes in having a small beard, and even some hair on the body, but no whiskers. (19. Catlin, 'North American Indians,' 3rd. ed. 1842, vol. ii. p. 227. On the Guaranys, see Azara, 'Voyages dans l'Amérique Merid.' tom. ii. 1809, p. 85; also Rengger, 'Säugethiere von Paraguay,' s. 3.) I am informed by Mr. D. Forbes, who particularly attended to this point, that the Aymaras and Quichuas of the Cordillera are remarkably hairless, yet in old age a few straggling hairs occasionally appear on the chin. The men of these two tribes have very little hair on the various parts of the body where hair grows abundantly in Europeans, and the women have none on the corresponding parts. The hair on the head, however, attains an extraordinary length in both sexes, often reaching almost to the ground; and this is likewise the case with some of the N. American tribes. In the amount of hair, and in the general shape of the body, the sexes of the American aborigines do not differ so much from each other, as in most other races. (20. Prof. and Mrs. Agassiz ('Journey in Brazil,' p. 530) remark that the sexes of the American Indians differ less than those of the negroes and of the higher races. See also Rengger, ibid. p. 3, on the Guaranys.) This fact is analogous with what occurs with some closely allied monkeys; thus the sexes of the chimpanzee are not as different as those of the orang or gorilla. (21. Rutimeyer, 'Die Grenzen der Thierwelt; eine Betrachtung zu Darwin's Lehre,' 1868, s. 54.) In the previous chapters we have seen that with mammals, birds, fishes, insects, etc., many characters, which there is every reason to believe were primarily gained through sexual selection by one sex, have been transferred to the other. As this same form of transmission has apparently prevailed much with mankind, it will save useless repetition if we discuss the origin of characters peculiar to the male sex together with certain other characters common to both sexes. LAW OF BATTLE. With savages, for instance, the Australians, the women are the constant cause of war both between members of the same tribe and between distinct tribes. So no doubt it was in ancient times; "nam fuit ante Helenam mulier teterrima belli causa." With some of the North American Indians, the contest is reduced to a system. That excellent observer, Hearne (22. 'A Journey from Prince of Wales Fort,' 8vo. ed. Dublin, 1796, p. 104. Sir J. Lubbock ('Origin of Civilisation,' 1870, p. 69) gives other and similar cases in North America. For the Guanas of South America see Azara, 'Voyages,' etc. tom. ii. p. 94.), says:--"It has ever been the custom among these people for the men to wrestle for any woman to whom they are attached; and, of course, the strongest party always carries off the prize. A weak man, unless he be a good hunter, and well-beloved, is seldom permitted to keep a wife that a stronger man thinks worth his notice. This custom prevails throughout all the tribes, and causes a great spirit of emulation among their youth, who are upon all occasions, from their childhood, trying their strength and skill in wrestling." With the Guanas of South America, Azara states that the men rarely marry till twenty years old or more, as before that age they cannot conquer their rivals. Other similar facts could be given; but even if we had no evidence on this head, we might feel almost sure, from the analogy of the higher Quadrumana (23. On the fighting of the male gorillas, see Dr. Savage, in 'Boston Journal of Natural History,' vol. v. 1847, p. 423. On Presbytis entellus, see the 'Indian Field,' 1859, p. 146.), that the law of battle had prevailed with man during the early stages of his development. The occasional appearance at the present day of canine teeth which project above the others, with traces of a diastema or open space for the reception of the opposite canines, is in all probability a case of reversion to a former state, when the progenitors of man were provided with these weapons, like so many existing male Quadrumana. It was remarked in a former chapter that as man gradually became erect, and continually used his hands and arms for fighting with sticks and stones, as well as for the other purposes of life, he would have used his jaws and teeth less and less. The jaws, together with their muscles, would then have been reduced through disuse, as would the teeth through the not well understood principles of correlation and economy of growth; for we everywhere see that parts, which are no longer of service, are reduced in size. By such steps the original inequality between the jaws and teeth in the two sexes of mankind would ultimately have been obliterated. The case is almost parallel with that of many male Ruminants, in which the canine teeth have been reduced to mere rudiments, or have disappeared, apparently in consequence of the development of horns. As the prodigious difference between the skulls of the two sexes in the orang and gorilla stands in close relation with the development of the immense canine teeth in the males, we may infer that the reduction of the jaws and teeth in the early male progenitors of man must have led to a most striking and favourable change in his appearance. There can be little doubt that the greater size and strength of man, in comparison with woman, together with his broader shoulders, more developed muscles, rugged outline of body, his greater courage and pugnacity, are all due in chief part to inheritance from his half-human male ancestors. These characters would, however, have been preserved or even augmented during the long ages of man's savagery, by the success of the strongest and boldest men, both in the general struggle for life and in their contests for wives; a success which would have ensured their leaving a more numerous progeny than their less favoured brethren. It is not probable that the greater strength of man was primarily acquired through the inherited effects of his having worked harder than woman for his own subsistence and that of his family; for the women in all barbarous nations are compelled to work at least as hard as the men. With civilised people the arbitrament of battle for the possession of the women has long ceased; on the other hand, the men, as a general rule, have to work harder than the women for their joint subsistence, and thus their greater strength will have been kept up. DIFFERENCE IN THE MENTAL POWERS OF THE TWO SEXES. With respect to differences of this nature between man and woman, it is probable that sexual selection has played a highly important part. I am aware that some writers doubt whether there is any such inherent difference; but this is at least probable from the analogy of the lower animals which present other secondary sexual characters. No one disputes that the bull differs in disposition from the cow, the wild-boar from the sow, the stallion from the mare, and, as is well known to the keepers of menageries, the males of the larger apes from the females. Woman seems to differ from man in mental disposition, chiefly in her greater tenderness and less selfishness; and this holds good even with savages, as shewn by a well-known passage in Mungo Park's Travels, and by statements made by many other travellers. Woman, owing to her maternal instincts, displays these qualities towards her infants in an eminent degree; therefore it is likely that she would often extend them towards her fellow-creatures. Man is the rival of other men; he delights in competition, and this leads to ambition which passes too easily into selfishness. These latter qualities seem to be his natural and unfortunate birthright. It is generally admitted that with woman the powers of intuition, of rapid perception, and perhaps of imitation, are more strongly marked than in man; but some, at least, of these faculties are characteristic of the lower races, and therefore of a past and lower state of civilisation. The chief distinction in the intellectual powers of the two sexes is shewn by man's attaining to a higher eminence, in whatever he takes up, than can woman--whether requiring deep thought, reason, or imagination, or merely the use of the senses and hands. If two lists were made of the most eminent men and women in poetry, painting, sculpture, music (inclusive both of composition and performance), history, science, and philosophy, with half-a-dozen names under each subject, the two lists would not bear comparison. We may also infer, from the law of the deviation from averages, so well illustrated by Mr. Galton, in his work on 'Hereditary Genius,' that if men are capable of a decided pre-eminence over women in many subjects, the average of mental power in man must be above that of woman. Amongst the half-human progenitors of man, and amongst savages, there have been struggles between the males during many generations for the possession of the females. But mere bodily strength and size would do little for victory, unless associated with courage, perseverance, and determined energy. With social animals, the young males have to pass through many a contest before they win a female, and the older males have to retain their females by renewed battles. They have, also, in the case of mankind, to defend their females, as well as their young, from enemies of all kinds, and to hunt for their joint subsistence. But to avoid enemies or to attack them with success, to capture wild animals, and to fashion weapons, requires the aid of the higher mental faculties, namely, observation, reason, invention, or imagination. These various faculties will thus have been continually put to the test and selected during manhood; they will, moreover, have been strengthened by use during this same period of life. Consequently in accordance with the principle often alluded to, we might expect that they would at least tend to be transmitted chiefly to the male offspring at the corresponding period of manhood. Now, when two men are put into competition, or a man with a woman, both possessed of every mental quality in equal perfection, save that one has higher energy, perseverance, and courage, the latter will generally become more eminent in every pursuit, and will gain the ascendancy. (24. J. Stuart Mill remarks ('The Subjection of Women,' 1869, p. 122), "The things in which man most excels woman are those which require most plodding, and long hammering at single thoughts." What is this but energy and perseverance?) He may be said to possess genius--for genius has been declared by a great authority to be patience; and patience, in this sense, means unflinching, undaunted perseverance. But this view of genius is perhaps deficient; for without the higher powers of the imagination and reason, no eminent success can be gained in many subjects. These latter faculties, as well as the former, will have been developed in man, partly through sexual selection,--that is, through the contest of rival males, and partly through natural selection, that is, from success in the general struggle for life; and as in both cases the struggle will have been during maturity, the characters gained will have been transmitted more fully to the male than to the female offspring. It accords in a striking manner with this view of the modification and re-inforcement of many of our mental faculties by sexual selection, that, firstly, they notoriously undergo a considerable change at puberty (25. Maudsley, 'Mind and Body,' p. 31.), and, secondly, that eunuchs remain throughout life inferior in these same qualities. Thus, man has ultimately become superior to woman. It is, indeed, fortunate that the law of the equal transmission of characters to both sexes prevails with mammals; otherwise, it is probable that man would have become as superior in mental endowment to woman, as the peacock is in ornamental plumage to the peahen. It must be borne in mind that the tendency in characters acquired by either sex late in life, to be transmitted to the same sex at the same age, and of early acquired characters to be transmitted to both sexes, are rules which, though general, do not always hold. If they always held good, we might conclude (but I here exceed my proper bounds) that the inherited effects of the early education of boys and girls would be transmitted equally to both sexes; so that the present inequality in mental power between the sexes would not be effaced by a similar course of early training; nor can it have been caused by their dissimilar early training. In order that woman should reach the same standard as man, she ought, when nearly adult, to be trained to energy and perseverance, and to have her reason and imagination exercised to the highest point; and then she would probably transmit these qualities chiefly to her adult daughters. All women, however, could not be thus raised, unless during many generations those who excelled in the above robust virtues were married, and produced offspring in larger numbers than other women. As before remarked of bodily strength, although men do not now fight for their wives, and this form of selection has passed away, yet during manhood, they generally undergo a severe struggle in order to maintain themselves and their families; and this will tend to keep up or even increase their mental powers, and, as a consequence, the present inequality between the sexes. (26. An observation by Vogt bears on this subject: he says, "It is a remarkable circumstance, that the difference between the sexes, as regards the cranial cavity, increases with the development of the race, so that the male European excels much more the female, than the negro the negress. Welcker confirms this statement of Huschke from his measurements of negro and German skulls." But Vogt admits ('Lectures on Man,' Eng. translat. 1864, p. 81) that more observations are requisite on this point. VOICE AND MUSICAL POWERS. In some species of Quadrumana there is a great difference between the adult sexes, in the power of their voices and in the development of the vocal organs; and man appears to have inherited this difference from his early progenitors. His vocal cords are about one-third longer than in woman, or than in boys; and emasculation produces the same effect on him as on the lower animals, for it "arrests that prominent growth of the thyroid, etc., which accompanies the elongation of the cords." (27. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 603.) With respect to the cause of this difference between the sexes, I have nothing to add to the remarks in the last chapter on the probable effects of the long-continued use of the vocal organs by the male under the excitement of love, rage and jealousy. According to Sir Duncan Gibb (28. 'Journal of the Anthropological Society,' April 1869, p. lvii. and lxvi.), the voice and the form of the larynx differ in the different races of mankind; but with the Tartars, Chinese, etc., the voice of the male is said not to differ so much from that of the female, as in most other races. The capacity and love for singing or music, though not a sexual character in man, must not here be passed over. Although the sounds emitted by animals of all kinds serve many purposes, a strong case can be made out, that the vocal organs were primarily used and perfected in relation to the propagation of the species. Insects and some few spiders are the lowest animals which voluntarily produce any sound; and this is generally effected by the aid of beautifully constructed stridulating organs, which are often confined to the males. The sounds thus produced consist, I believe in all cases, of the same note, repeated rhythmically (29. Dr. Scudder, 'Notes on Stridulation,' in 'Proc. Boston Soc. of Nat. Hist.' vol. xi. April 1868.); and this is sometimes pleasing even to the ears of man. The chief and, in some cases, exclusive purpose appears to be either to call or charm the opposite sex. The sounds produced by fishes are said in some cases to be made only by the males during the breeding-season. All the air-breathing Vertebrata necessarily possess an apparatus for inhaling and expelling air, with a pipe capable of being closed at one end. Hence when the primeval members of this class were strongly excited and their muscles violently contracted, purposeless sounds would almost certainly have been produced; and these, if they proved in any way serviceable, might readily have been modified or intensified by the preservation of properly adapted variations. The lowest Vertebrates which breathe air are Amphibians; and of these, frogs and toads possess vocal organs, which are incessantly used during the breeding-season, and which are often more highly developed in the male than in the female. The male alone of the tortoise utters a noise, and this only during the season of love. Male alligators roar or bellow during the same season. Every one knows how much birds use their vocal organs as a means of courtship; and some species likewise perform what may be called instrumental music. In the class of Mammals, with which we are here more particularly concerned, the males of almost all the species use their voices during the breeding-season much more than at any other time; and some are absolutely mute excepting at this season. With other species both sexes, or only the females, use their voices as a love-call. Considering these facts, and that the vocal organs of some quadrupeds are much more largely developed in the male than in the female, either permanently or temporarily during the breeding-season; and considering that in most of the lower classes the sounds produced by the males, serve not only to call but to excite or allure the female, it is a surprising fact that we have not as yet any good evidence that these organs are used by male mammals to charm the females. The American Mycetes caraya perhaps forms an exception, as does the Hylobates agilis, an ape allied to man. This gibbon has an extremely loud but musical voice. Mr. Waterhouse states (30. Given in W.C.L. Martin's 'General Introduction to Natural History of Mamm. Animals,' 1841, p. 432; Owen, 'Anatomy of Vertebrates,' vol. iii, p. 600.), "It appeared to me that in ascending and descending the scale, the intervals were always exactly half-tones; and I am sure that the highest note was the exact octave to the lowest. The quality of the notes is very musical; and I do not doubt that a good violinist would be able to give a correct idea of the gibbon's composition, excepting as regards its loudness." Mr. Waterhouse then gives the notes. Professor Owen, who is a musician, confirms the foregoing statement, and remarks, though erroneously, that this gibbon "alone of brute mammals may be said to sing." It appears to be much excited after its performance. Unfortunately, its habits have never been closely observed in a state of nature; but from the analogy of other animals, it is probable that it uses its musical powers more especially during the season of courtship. This gibbon is not the only species in the genus which sings, for my son, Francis Darwin, attentively listened in the Zoological Gardens to H. leuciscus whilst singing a cadence of three notes, in true musical intervals and with a clear musical tone. It is a more surprising fact that certain rodents utter musical sounds. Singing mice have often been mentioned and exhibited, but imposture has commonly been suspected. We have, however, at last a clear account by a well-known observer, the Rev. S. Lockwood (31. The 'American Naturalist,' 1871, p. 761.), of the musical powers of an American species, the Hesperomys cognatus, belonging to a genus distinct from that of the English mouse. This little animal was kept in confinement, and the performance was repeatedly heard. In one of the two chief songs, "the last bar would frequently be prolonged to two or three; and she would sometimes change from C sharp and D, to C natural and D, then warble on these two notes awhile, and wind up with a quick chirp on C sharp and D. The distinctness between the semitones was very marked, and easily appreciable to a good ear." Mr. Lockwood gives both songs in musical notation; and adds that though this little mouse "had no ear for time, yet she would keep to the key of B (two flats) and strictly in a major key."..."Her soft clear voice falls an octave with all the precision possible; then at the wind up, it rises again into a very quick trill on C sharp and D." A critic has asked how the ears of man, and he ought to have added of other animals, could have been adapted by selection so as to distinguish musical notes. But this question shews some confusion on the subject; a noise is the sensation resulting from the co-existence of several aerial "simple vibrations" of various periods, each of which intermits so frequently that its separate existence cannot be perceived. It is only in the want of continuity of such vibrations, and in their want of harmony inter se, that a noise differs from a musical note. Thus an ear to be capable of discriminating noises--and the high importance of this power to all animals is admitted by every one--must be sensitive to musical notes. We have evidence of this capacity even low down in the animal scale: thus Crustaceans are provided with auditory hairs of different lengths, which have been seen to vibrate when the proper musical notes are struck. (32. Helmholtz, 'Theorie Phys. de la Musique,' 1868, p. 187.) As stated in a previous chapter, similar observations have been made on the hairs of the antennae of gnats. It has been positively asserted by good observers that spiders are attracted by music. It is also well known that some dogs howl when hearing particular tones. (33. Several accounts have been published to this effect. Mr. Peach writes to me that an old dog of his howls when B flat is sounded on the flute, and to no other note. I may add another instance of a dog always whining, when one note on a concertina, which was out of tune, was played.) Seals apparently appreciate music, and their fondness for it "was well known to the ancients, and is often taken advantage of by the hunters at the present day." (34. Mr. R. Brown, in 'Proc. Zool. Soc.' 1868, p. 410.) Therefore, as far as the mere perception of musical notes is concerned, there seems no special difficulty in the case of man or of any other animal. Helmholtz has explained on physiological principles why concords are agreeable, and discords disagreeable to the human ear; but we are little concerned with these, as music in harmony is a late invention. We are more concerned with melody, and here again, according to Helmholtz, it is intelligible why the notes of our musical scale are used. The ear analyses all sounds into their component "simple vibrations," although we are not conscious of this analysis. In a musical note the lowest in pitch of these is generally predominant, and the others which are less marked are the octave, the twelfth, the second octave, etc., all harmonies of the fundamental predominant note; any two notes of our scale have many of these harmonic over-tones in common. It seems pretty clear then, that if an animal always wished to sing precisely the same song, he would guide himself by sounding those notes in succession, which possess many over-tones in common--that is, he would choose for his song, notes which belong to our musical scale. But if it be further asked why musical tones in a certain order and rhythm give man and other animals pleasure, we can no more give the reason than for the pleasantness of certain tastes and smells. That they do give pleasure of some kind to animals, we may infer from their being produced during the season of courtship by many insects, spiders, fishes, amphibians, and birds; for unless the females were able to appreciate such sounds and were excited or charmed by them, the persevering efforts of the males, and the complex structures often possessed by them alone, would be useless; and this it is impossible to believe. Human song is generally admitted to be the basis or origin of instrumental music. As neither the enjoyment nor the capacity of producing musical notes are faculties of the least use to man in reference to his daily habits of life, they must be ranked amongst the most mysterious with which he is endowed. They are present, though in a very rude condition, in men of all races, even the most savage; but so different is the taste of the several races, that our music gives no pleasure to savages, and their music is to us in most cases hideous and unmeaning. Dr. Seemann, in some interesting remarks on this subject (35. 'Journal of Anthropological Society,' Oct. 1870, p. clv. See also the several later chapters in Sir John Lubbock's 'Prehistoric Times,' 2nd ed. 1869, which contain an admirable account of the habits of savages.), "doubts whether even amongst the nations of Western Europe, intimately connected as they are by close and frequent intercourse, the music of the one is interpreted in the same sense by the others. By travelling eastwards we find that there is certainly a different language of music. Songs of joy and dance-accompaniments are no longer, as with us, in the major keys, but always in the minor." Whether or not the half-human progenitors of man possessed, like the singing gibbons, the capacity of producing, and therefore no doubt of appreciating, musical notes, we know that man possessed these faculties at a very remote period. M. Lartet has described two flutes made out of the bones and horns of the reindeer, found in caves together with flint tools and the remains of extinct animals. The arts of singing and of dancing are also very ancient, and are now practised by all or nearly all the lowest races of man. Poetry, which may be considered as the offspring of song, is likewise so ancient, that many persons have felt astonished that it should have arisen during the earliest ages of which we have any record. We see that the musical faculties, which are not wholly deficient in any race, are capable of prompt and high development, for Hottentots and Negroes have become excellent musicians, although in their native countries they rarely practise anything that we should consider music. Schweinfurth, however, was pleased with some of the simple melodies which he heard in the interior of Africa. But there is nothing anomalous in the musical faculties lying dormant in man: some species of birds which never naturally sing, can without much difficulty be taught to do so; thus a house-sparrow has learnt the song of a linnet. As these two species are closely allied, and belong to the order of Insessores, which includes nearly all the singing-birds in the world, it is possible that a progenitor of the sparrow may have been a songster. It is more remarkable that parrots, belonging to a group distinct from the Insessores, and having differently constructed vocal organs, can be taught not only to speak, but to pipe or whistle tunes invented by man, so that they must have some musical capacity. Nevertheless it would be very rash to assume that parrots are descended from some ancient form which was a songster. Many cases could be advanced of organs and instincts originally adapted for one purpose, having been utilised for some distinct purpose. (36. Since this chapter was printed, I have seen a valuable article by Mr. Chauncey Wright ('North American Review,' Oct. 1870, page 293), who, in discussing the above subject, remarks, "There are many consequences of the ultimate laws or uniformities of nature, through which the acquisition of one useful power will bring with it many resulting advantages as well as limiting disadvantages, actual or possible, which the principle of utility may not have comprehended in its action." As I have attempted to shew in an early chapter of this work, this principle has an important bearing on the acquisition by man of some of his mental characteristics.) Hence the capacity for high musical development which the savage races of man possess, may be due either to the practice by our semi-human progenitors of some rude form of music, or simply to their having acquired the proper vocal organs for a different purpose. But in this latter case we must assume, as in the above instance of parrots, and as seems to occur with many animals, that they already possessed some sense of melody. Music arouses in us various emotions, but not the more terrible ones of horror, fear, rage, etc. It awakens the gentler feelings of tenderness and love, which readily pass into devotion. In the Chinese annals it is said, "Music hath the power of making heaven descend upon earth." It likewise stirs up in us the sense of triumph and the glorious ardour for war. These powerful and mingled feelings may well give rise to the sense of sublimity. We can concentrate, as Dr. Seemann observes, greater intensity of feeling in a single musical note than in pages of writing. It is probable that nearly the same emotions, but much weaker and far less complex, are felt by birds when the male pours forth his full volume of song, in rivalry with other males, to captivate the female. Love is still the commonest theme of our songs. As Herbert Spencer remarks, "music arouses dormant sentiments of which we had not conceived the possibility, and do not know the meaning; or, as Richter says, tells us of things we have not seen and shall not see." Conversely, when vivid emotions are felt and expressed by the orator, or even in common speech, musical cadences and rhythm are instinctively used. The negro in Africa when excited often bursts forth in song; "another will reply in song, whilst the company, as if touched by a musical wave, murmur a chorus in perfect unison." (37. Winwood Reade, 'The Martyrdom of Man,' 1872, p. 441, and 'African Sketch Book,' 1873, vol. ii. p. 313.) Even monkeys express strong feelings in different tones--anger and impatience by low,--fear and pain by high notes. (38. Rengger, 'Säugethiere von Paraguay,' s. 49.) The sensations and ideas thus excited in us by music, or expressed by the cadences of oratory, appear from their vagueness, yet depth, like mental reversions to the emotions and thoughts of a long-past age. All these facts with respect to music and impassioned speech become intelligible to a certain extent, if we may assume that musical tones and rhythm were used by our half-human ancestors, during the season of courtship, when animals of all kinds are excited not only by love, but by the strong passions of jealousy, rivalry, and triumph. From the deeply-laid principle of inherited associations, musical tones in this case would be likely to call up vaguely and indefinitely the strong emotions of a long-past age. As we have every reason to suppose that articulate speech is one of the latest, as it certainly is the highest, of the arts acquired by man, and as the instinctive power of producing musical notes and rhythms is developed low down in the animal series, it would be altogether opposed to the principle of evolution, if we were to admit that man's musical capacity has been developed from the tones used in impassioned speech. We must suppose that the rhythms and cadences of oratory are derived from previously developed musical powers. (39. See the very interesting discussion on the 'Origin and Function of Music,' by Mr. Herbert Spencer, in his collected 'Essays,' 1858, p. 359. Mr. Spencer comes to an exactly opposite conclusion to that at which I have arrived. He concludes, as did Diderot formerly, that the cadences used in emotional speech afford the foundation from which music has been developed; whilst I conclude that musical notes and rhythm were first acquired by the male or female progenitors of mankind for the sake of charming the opposite sex. Thus musical tones became firmly associated with some of the strongest passions an animal is capable of feeling, and are consequently used instinctively, or through association when strong emotions are expressed in speech. Mr. Spencer does not offer any satisfactory explanation, nor can I, why high or deep notes should be expressive, both with man and the lower animals, of certain emotions. Mr. Spencer gives also an interesting discussion on the relations between poetry, recitative and song.) We can thus understand how it is that music, dancing, song, and poetry are such very ancient arts. We may go even further than this, and, as remarked in a former chapter, believe that musical sounds afforded one of the bases for the development of language. (40. I find in Lord Monboddo's 'Origin of Language,' vol. i. 1774, p. 469, that Dr. Blacklock likewise thought "that the first language among men was music, and that before our ideas were expressed by articulate sounds, they were communicated by tones varied according to different degrees of gravity and acuteness.") As the males of several quadrumanous animals have their vocal organs much more developed than in the females, and as a gibbon, one of the anthropomorphous apes, pours forth a whole octave of musical notes and may be said to sing, it appears probable that the progenitors of man, either the males or females or both sexes, before acquiring the power of expressing their mutual love in articulate language, endeavoured to charm each other with musical notes and rhythm. So little is known about the use of the voice by the Quadrumana during the season of love, that we have no means of judging whether the habit of singing was first acquired by our male or female ancestors. Women are generally thought to possess sweeter voices than men, and as far as this serves as any guide, we may infer that they first acquired musical powers in order to attract the other sex. (41. See an interesting discussion on this subject by Haeckel, 'Generelle Morphologie,' B. ii. 1866, s. 246.) But if so, this must have occurred long ago, before our ancestors had become sufficiently human to treat and value their women merely as useful slaves. The impassioned orator, bard, or musician, when with his varied tones and cadences he excites the strongest emotions in his hearers, little suspects that he uses the same means by which his half-human ancestors long ago aroused each other's ardent passions, during their courtship and rivalry. THE INFLUENCE OF BEAUTY IN DETERMINING THE MARRIAGES OF MANKIND. In civilised life man is largely, but by no means exclusively, influenced in the choice of his wife by external appearance; but we are chiefly concerned with primeval times, and our only means of forming a judgment on this subject is to study the habits of existing semi-civilised and savage nations. If it can be shewn that the men of different races prefer women having various characteristics, or conversely with the women, we have then to enquire whether such choice, continued during many generations, would produce any sensible effect on the race, either on one sex or both according to the form of inheritance which has prevailed. It will be well first to shew in some detail that savages pay the greatest attention to their personal appearance. (42. A full and excellent account of the manner in which savages in all parts of the world ornament themselves, is given by the Italian traveller, Professor Mantegazza, 'Rio de la Plata, Viaggi e Studi,' 1867, pp. 525-545; all the following statements, when other references are not given, are taken from this work. See, also, Waitz, 'Introduction to Anthropology,' Eng. translat. vol. i. 1863, p. 275, et passim. Lawrence also gives very full details in his 'Lectures on Physiology,' 1822. Since this chapter was written Sir J. Lubbock has published his 'Origin of Civilisation,' 1870, in which there is an interesting chapter on the present subject, and from which (pp. 42, 48) I have taken some facts about savages dyeing their teeth and hair, and piercing their teeth.) That they have a passion for ornament is notorious; and an English philosopher goes so far as to maintain, that clothes were first made for ornament and not for warmth. As Professor Waitz remarks, "however poor and miserable man is, he finds a pleasure in adorning himself." The extravagance of the naked Indians of South America in decorating themselves is shewn "by a man of large stature gaining with difficulty enough by the labour of a fortnight to procure in exchange the chica necessary to paint himself red." (43. Humboldt, 'Personal Narrative,' Eng. translat. vol. iv. p. 515; on the imagination shewn in painting the body, p. 522; on modifying the form of the calf of the leg, p. 466.) The ancient barbarians of Europe during the Reindeer period brought to their caves any brilliant or singular objects which they happened to find. Savages at the present day everywhere deck themselves with plumes, necklaces, armlets, ear-rings, etc. They paint themselves in the most diversified manner. "If painted nations," as Humboldt observes, "had been examined with the same attention as clothed nations, it would have been perceived that the most fertile imagination and the most mutable caprice have created the fashions of painting, as well as those of garments." In one part of Africa the eyelids are coloured black; in another the nails are coloured yellow or purple. In many places the hair is dyed of various tints. In different countries the teeth are stained black, red, blue, etc., and in the Malay Archipelago it is thought shameful to have white teeth "like those of a dog." Not one great country can be named, from the polar regions in the north to New Zealand in the south, in which the aborigines do not tattoo themselves. This practice was followed by the Jews of old, and by the ancient Britons. In Africa some of the natives tattoo themselves, but it is a much more common practice to raise protuberances by rubbing salt into incisions made in various parts of the body; and these are considered by the inhabitants of Kordofan and Darfur "to be great personal attractions." In the Arab countries no beauty can be perfect until the cheeks "or temples have been gashed." (44. 'The Nile Tributaries,' 1867; 'The Albert N'yanza,' 1866, vol. i. p. 218.) In South America, as Humboldt remarks, "a mother would be accused of culpable indifference towards her children, if she did not employ artificial means to shape the calf of the leg after the fashion of the country." In the Old and New Worlds the shape of the skull was formerly modified during infancy in the most extraordinary manner, as is still the case in many places, and such deformities are considered ornamental. For instance, the savages of Colombia (45. Quoted by Prichard, 'Physical History of Mankind,' 4th ed. vol. i. 1851, p. 321.) deem a much flattened head "an essential point of beauty." The hair is treated with especial care in various countries; it is allowed to grow to full length, so as to reach to the ground, or is combed into "a compact frizzled mop, which is the Papuan's pride and glory." (46. On the Papuans, Wallace, 'The Malay Archipelago,' vol. ii. p. 445. On the coiffure of the Africans, Sir S. Baker, 'The Albert N'yanza,' vol. i. p. 210.) In northern Africa "a man requires a period of from eight to ten years to perfect his coiffure." With other nations the head is shaved, and in parts of South America and Africa even the eyebrows and eyelashes are eradicated. The natives of the Upper Nile knock out the four front teeth, saying that they do not wish to resemble brutes. Further south, the Batokas knock out only the two upper incisors, which, as Livingstone (47. 'Travels,' p. 533.) remarks, gives the face a hideous appearance, owing to the prominence of the lower jaw; but these people think the presence of the incisors most unsightly, and on beholding some Europeans, cried out, "Look at the great teeth!" The chief Sebituani tried in vain to alter this fashion. In various parts of Africa and in the Malay Archipelago the natives file the incisors into points like those of a saw, or pierce them with holes, into which they insert studs. As the face with us is chiefly admired for its beauty, so with savages it is the chief seat of mutilation. In all quarters of the world the septum, and more rarely the wings of the nose are pierced; rings, sticks, feathers, and other ornaments being inserted into the holes. The ears are everywhere pierced and similarly ornamented, and with the Botocudos and Lenguas of South America the hole is gradually so much enlarged that the lower edge touches the shoulder. In North and South America and in Africa either the upper or lower lip is pierced; and with the Botocudos the hole in the lower lip is so large that a disc of wood, four inches in diameter, is placed in it. Mantegazza gives a curious account of the shame felt by a South American native, and of the ridicule which he excited, when he sold his tembeta,--the large coloured piece of wood which is passed through the hole. In Central Africa the women perforate the lower lip and wear a crystal, which, from the movement of the tongue, has "a wriggling motion, indescribably ludicrous during conversation." The wife of the chief of Latooka told Sir S. Baker (49. 'The Albert N'yanza,' 1866, vol. i. p. 217.) that Lady Baker "would be much improved if she would extract her four front teeth from the lower jaw, and wear the long pointed polished crystal in her under lip." Further south with the Makalolo, the upper lip is perforated, and a large metal and bamboo ring, called a pelele, is worn in the hole. "This caused the lip in one case to project two inches beyond the tip of the nose; and when the lady smiled, the contraction of the muscles elevated it over the eyes. 'Why do the women wear these things?' the venerable chief, Chinsurdi, was asked. Evidently surprised at such a stupid question, he replied, 'For beauty! They are the only beautiful things women have; men have beards, women have none. What kind of a person would she be without the pelele? She would not be a woman at all with a mouth like a man, but no beard.'" (49. Livingstone, 'British Association,' 1860; report given in the 'Athenaeum,' July 7, 1860, p. 29.) Hardly any part of the body, which can be unnaturally modified, has escaped. The amount of suffering thus caused must have been extreme, for many of the operations require several years for their completion, so that the idea of their necessity must be imperative. The motives are various; the men paint their bodies to make themselves appear terrible in battle; certain mutilations are connected with religious rites, or they mark the age of puberty, or the rank of the man, or they serve to distinguish the tribes. Amongst savages the same fashions prevail for long periods (50. Sir S. Baker (ibid. vol. i. p. 210) speaking of the natives of Central Africa says, "every tribe has a distinct and unchanging fashion for dressing the hair." See Agassiz ('Journey in Brazil,' 1868, p. 318) on invariability of the tattooing of Amazonian Indians.), and thus mutilations, from whatever cause first made, soon come to be valued as distinctive marks. But self-adornment, vanity, and the admiration of others, seem to be the commonest motives. In regard to tattooing, I was told by the missionaries in New Zealand that when they tried to persuade some girls to give up the practice, they answered, "We must just have a few lines on our lips; else when we grow old we shall be so very ugly." With the men of New Zealand, a most capable judge (51. Rev. R. Taylor, 'New Zealand and its Inhabitants,' 1855, p. 152.) says, "to have fine tattooed faces was the great ambition of the young, both to render themselves attractive to the ladies, and conspicuous in war." A star tattooed on the forehead and a spot on the chin are thought by the women in one part of Africa to be irresistible attractions. (52. Mantegazza, 'Viaggi e Studi,' p. 542.) In most, but not all parts of the world, the men are more ornamented than the women, and often in a different manner; sometimes, though rarely, the women are hardly at all ornamented. As the women are made by savages to perform the greatest share of the work, and as they are not allowed to eat the best kinds of food, so it accords with the characteristic selfishness of man that they should not be allowed to obtain, or use the finest ornaments. Lastly, it is a remarkable fact, as proved by the foregoing quotations, that the same fashions in modifying the shape of the head, in ornamenting the hair, in painting, tattooing, in perforating the nose, lips, or ears, in removing or filing the teeth, etc., now prevail, and have long prevailed, in the most distant quarters of the world. It is extremely improbable that these practices, followed by so many distinct nations, should be due to tradition from any common source. They indicate the close similarity of the mind of man, to whatever race he may belong, just as do the almost universal habits of dancing, masquerading, and making rude pictures. Having made these preliminary remarks on the admiration felt by savages for various ornaments, and for deformities most unsightly in our eyes, let us see how far the men are attracted by the appearance of their women, and what are their ideas of beauty. I have heard it maintained that savages are quite indifferent about the beauty of their women, valuing them solely as slaves; it may therefore be well to observe that this conclusion does not at all agree with the care which the women take in ornamenting themselves, or with their vanity. Burchell (53. 'Travels in South Africa,' 1824, vol. i. p. 414.) gives an amusing account of a Bush-woman who used as much grease, red ochre, and shining powder "as would have ruined any but a very rich husband." She displayed also "much vanity and too evident a consciousness of her superiority." Mr. Winwood Reade informs me that the negroes of the West Coast often discuss the beauty of their women. Some competent observers have attributed the fearfully common practice of infanticide partly to the desire felt by the women to retain their good looks. (54. See, for references, Gerland, 'Ueber das Aussterben der Naturvölker,' 1868, ss. 51, 53, 55; also Azara, 'Voyages,' etc., tom. ii. p. 116.) In several regions the women wear charms and use love-philters to gain the affections of the men; and Mr. Brown enumerates four plants used for this purpose by the women of North-Western America. (55. On the vegetable productions used by the North-Western American Indians, see 'Pharmaceutical Journal,' vol. x.) Hearne (56. 'A Journey from Prince of Wales Fort,' 8vo. ed. 1796, p. 89.), an excellent observer, who lived many years with the American Indians, says, in speaking of the women, "Ask a Northern Indian what is beauty, and he will answer, a broad flat face, small eyes, high cheek-bones, three or four broad black lines across each cheek, a low forehead, a large broad chin, a clumsy hook nose, a tawny hide, and breasts hanging down to the belt." Pallas, who visited the northern parts of the Chinese empire, says, "those women are preferred who have the Mandschu form; that is to say, a broad face, high cheek-bones, very broad noses, and enormous ears"(57. Quoted by Prichard, 'Physical History of Mankind,' 3rd ed. vol. iv. 1844, p. 519; Vogt, 'Lectures on Man,' Eng. translat. p. 129. On the opinion of the Chinese on the Cingalese, E. Tennent, 'Ceylon,' 1859, vol. ii. p. 107.); and Vogt remarks that the obliquity of the eye, which is proper to the Chinese and Japanese, is exaggerated in their pictures for the purpose, as it "seems, of exhibiting its beauty, as contrasted with the eye of the red-haired barbarians." It is well known, as Huc repeatedly remarks, that the Chinese of the interior think Europeans hideous, with their white skins and prominent noses. The nose is far from being too prominent, according to our ideas, in the natives of Ceylon; yet "the Chinese in the seventh century, accustomed to the flat features of the Mongol races, were surprised at the prominent noses of the Cingalese; and Thsang described them as having 'the beak of a bird, with the body of a man.'" Finlayson, after minutely describing the people of Cochin China, says that their rounded heads and faces are their chief characteristics; and, he adds, "the roundness of the whole countenance is more striking in the women, who are reckoned beautiful in proportion as they display this form of face." The Siamese have small noses with divergent nostrils, a wide mouth, rather thick lips, a remarkably large face, with very high and broad cheek-bones. It is, therefore, not wonderful that "beauty, according to our notion, is a stranger to them. Yet they consider their own females to be much more beautiful than those of Europe." (58. Prichard, as taken from Crawfurd and Finlayson, 'Phys. Hist. of Mankind,' vol. iv. pp. 534, 535.) It is well known that with many Hottentot women the posterior part of the body projects in a wonderful manner; they are steatopygous; and Sir Andrew Smith is certain that this peculiarity is greatly admired by the men. (59. Idem illustrissimus viator dixit mihi praecinctorium vel tabulam foeminae, quod nobis teterrimum est, quondam permagno aestimari ab hominibus in hac gente. Nunc res mutata est, et censent talem conformationem minime optandam esse.) He once saw a woman who was considered a beauty, and she was so immensely developed behind, that when seated on level ground she could not rise, and had to push herself along until she came to a slope. Some of the women in various negro tribes have the same peculiarity; and, according to Burton, the Somal men are said to choose their wives by ranging them in a line, and by picking her out who projects farthest a tergo. Nothing can be more hateful to a negro than the opposite form." (60. The 'Anthropological Review,' November 1864, p. 237. For additional references, see Waitz, 'Introduction to Anthropology,' Eng. translat., 1863, vol. i. p. 105.) With respect to colour, the negroes rallied Mungo Park on the whiteness of his skin and the prominence of his nose, both of which they considered as "unsightly and unnatural conformations." He in return praised the glossy jet of their skins and the lovely depression of their noses; this they said was "honeymouth," nevertheless they gave him food. The African Moors, also, "knitted their brows and seemed to shudder" at the whiteness of his skin. On the eastern coast, the negro boys when they saw Burton, cried out, "Look at the white man; does he not look like a white ape?" On the western coast, as Mr. Winwood Reade informs me, the negroes admire a very black skin more than one of a lighter tint. But their horror of whiteness may be attributed, according to this same traveller, partly to the belief held by most negroes that demons and spirits are white, and partly to their thinking it a sign of ill-health. The Banyai of the more southern part of the continent are negroes, but "a great many of them are of a light coffee-and-milk colour, and, indeed, this colour is considered handsome throughout the whole country"; so that here we have a different standard of taste. With the Kaffirs, who differ much from negroes, "the skin, except among the tribes near Delagoa Bay, is not usually black, the prevailing colour being a mixture of black and red, the most common shade being chocolate. Dark complexions, as being most common, are naturally held in the highest esteem. To be told that he is light-coloured, or like a white man, would be deemed a very poor compliment by a Kaffir. I have heard of one unfortunate man who was so very fair that no girl would marry him." One of the titles of the Zulu king is, "You who are black." (61. Mungo Park's 'Travels in Africa,' 4to. 1816, pp. 53, 131. Burton's statement is quoted by Schaaffhausen, 'Archiv. fur Anthropologie,' 1866, s. 163. On the Banyai, Livingstone, 'Travels,' p. 64. On the Kaffirs, the Rev. J. Shooter, 'The Kafirs of Natal and the Zulu Country,' 1857, p. 1.) Mr. Galton, in speaking to me about the natives of S. Africa, remarked that their ideas of beauty seem very different from ours; for in one tribe two slim, slight, and pretty girls were not admired by the natives. Turning to other quarters of the world; in Java, a yellow, not a white girl, is considered, according to Madame Pfeiffer, a beauty. A man of Cochin China "spoke with contempt of the wife of the English Ambassador, that she had white teeth like a dog, and a rosy colour like that of potato-flowers." We have seen that the Chinese dislike our white skin, and that the N. Americans admire "a tawny hide." In S. America, the Yuracaras, who inhabit the wooded, damp slopes of the eastern Cordillera, are remarkably pale-coloured, as their name in their own language expresses; nevertheless they consider European women as very inferior to their own. (62. For the Javans and Cochin-Chinese, see Waitz, 'Introduct. to Anthropology,' Eng. translat. vol. i. p. 305. On the Yuracaras, A. d'Orbigny, as quoted in Prichard, 'Physical History of Mankind,' vol. v. 3rd ed. p. 476.) In several of the tribes of North America the hair on the head grows to a wonderful length; and Catlin gives a curious proof how much this is esteemed, for the chief of the Crows was elected to this office from having the longest hair of any man in the tribe, namely ten feet and seven inches. The Aymaras and Quichuas of S. America, likewise have very long hair; and this, as Mr. D. Forbes informs me, is so much valued as a beauty, that cutting it off was the severest punishment which he could inflict on them. In both the Northern and Southern halves of the continent the natives sometimes increase the apparent length of their hair by weaving into it fibrous substances. Although the hair on the head is thus cherished, that on the face is considered by the North American Indians "as very vulgar," and every hair is carefully eradicated. This practice prevails throughout the American continent from Vancouver's Island in the north to Tierra del Fuego in the south. When York Minster, a Fuegian on board the "Beagle," was taken back to his country, the natives told him he ought to pull out the few short hairs on his face. They also threatened a young missionary, who was left for a time with them, to strip him naked, and pluck the hair from his face and body, yet he was far from being a hairy man. This fashion is carried so far that the Indians of Paraguay eradicate their eyebrows and eyelashes, saying that they do not wish to be like horses. (63. 'North American Indians,' by G. Catlin, 3rd ed., 1842, vol. i. p. 49; vol. ii, p. 227. On the natives of Vancouver's Island, see Sproat, 'Scenes and Studies of Savage Life,' 1868, p. 25. On the Indians of Paraguay, Azara, 'Voyages,' tom. ii. p. 105.) It is remarkable that throughout the world the races which are almost completely destitute of a beard dislike hairs on the face and body, and take pains to eradicate them. The Kalmucks are beardless, and they are well known, like the Americans, to pluck out all straggling hairs; and so it is with the Polynesians, some of the Malays, and the Siamese. Mr. Veitch states that the Japanese ladies "all objected to our whiskers, considering them very ugly, and told us to cut them off, and be like Japanese men." The New Zealanders have short, curled beards; yet they formerly plucked out the hairs on the face. They had a saying that "there is no woman for a hairy man;" but it would appear that the fashion has changed in New Zealand, perhaps owing to the presence of Europeans, and I am assured that beards are now admired by the Maories. (64. On the Siamese, Prichard, ibid. vol. iv. p. 533. On the Japanese, Veitch in 'Gardeners' Chronicle,' 1860, p. 1104. On the New Zealanders, Mantegazza, 'Viaggi e Studi,' 1867, p. 526. For the other nations mentioned, see references in Lawrence, 'Lectures on Physiology,' etc., 1822, p. 272.) On the other hand, bearded races admire and greatly value their beards; among the Anglo-Saxons every part of the body had a recognised value; "the loss of the beard being estimated at twenty shillings, while the breaking of a thigh was fixed at only twelve." (65. Lubbock, 'Origin of Civilisation,' 1870, p. 321.) In the East men swear solemnly by their beards. We have seen that Chinsurdi, the chief of the Makalolo in Africa, thought that beards were a great ornament. In the Pacific the Fijian's beard is "profuse and bushy, and is his greatest pride"; whilst the inhabitants of the adjacent archipelagoes of Tonga and Samoa are "beardless, and abhor a rough chin." In one island alone of the Ellice group "the men are heavily bearded, and not a little proud thereof." (66. Dr. Barnard Davis quotes Mr. Prichard and others for these facts in regard to the Polynesians, in 'Anthropolog. Review,' April 1870, pp. 185, 191.) We thus see how widely the different races of man differ in their taste for the beautiful. In every nation sufficiently advanced to have made effigies of their gods or of their deified rulers, the sculptors no doubt have endeavoured to express their highest ideal of beauty and grandeur. (67. Ch. Comte has remarks to this effect in his 'Traité de Législation,' 3rd ed. 1837, p. 136.) Under this point of view it is well to compare in our mind the Jupiter or Apollo of the Greeks with the Egyptian or Assyrian statues; and these with the hideous bas-reliefs on the ruined buildings of Central America. I have met with very few statements opposed to this conclusion. Mr. Winwood Reade, however, who has had ample opportunities for observation, not only with the negroes of the West Coast of Africa, but with those of the interior who have never associated with Europeans, is convinced that their ideas of beauty are ON THE WHOLE the same as ours; and Dr. Rohlfs writes to me to the same effect with respect to Bornu and the countries inhabited by the Pullo tribes. Mr. Reade found that he agreed with the negroes in their estimation of the beauty of the native girls; and that their appreciation of the beauty of European women corresponded with ours. They admire long hair, and use artificial means to make it appear abundant; they admire also a beard, though themselves very scantily provided. Mr. Reade feels doubtful what kind of nose is most appreciated; a girl has been heard to say, "I do not want to marry him, he has got no nose"; and this shews that a very flat nose is not admired. We should, however, bear in mind that the depressed, broad noses and projecting jaws of the negroes of the West Coast are exceptional types with the inhabitants of Africa. Notwithstanding the foregoing statements, Mr. Reade admits that negroes "do not like the colour of our skin; they look on blue eyes with aversion, and they think our noses too long and our lips too thin." He does not think it probable that negroes would ever prefer the most beautiful European woman, on the mere grounds of physical admiration, to a good-looking negress. (68. The 'African Sketch Book,' vol. ii. 1873, pp. 253, 394, 521. The Fuegians, as I have been informed by a missionary who long resided with them, consider European women as extremely beautiful; but from what we have seen of the judgment of the other aborigines of America, I cannot but think that this must be a mistake, unless indeed the statement refers to the few Fuegians who have lived for some time with Europeans, and who must consider us as superior beings. I should add that a most experienced observer, Capt. Burton, believes that a woman whom we consider beautiful is admired throughout the world. 'Anthropological Review,' March, 1864, p. 245.) The general truth of the principle, long ago insisted on by Humboldt (69. 'Personal Narrative,' Eng. translat. vol. iv. p. 518, and elsewhere. Mantegazza, in his 'Viaggi e Studi,' strongly insists on this same principle.), that man admires and often tries to exaggerate whatever characters nature may have given him, is shewn in many ways. The practice of beardless races extirpating every trace of a beard, and often all the hairs on the body affords one illustration. The skull has been greatly modified during ancient and modern times by many nations; and there can be little doubt that this has been practised, especially in N. and S. America, in order to exaggerate some natural and admired peculiarity. Many American Indians are known to admire a head so extremely flattened as to appear to us idiotic. The natives on the north-western coast compress the head into a pointed cone; and it is their constant practice to gather the hair into a knot on the top of the head, for the sake, as Dr. Wilson remarks, "of increasing the apparent elevation of the favourite conoid form." The inhabitants of Arakhan admire a broad, smooth forehead, and in order to produce it, they fasten a plate of lead on the heads of the new-born children. On the other hand, "a broad, well-rounded occiput is considered a great beauty" by the natives of the Fiji Islands. (70. On the skulls of the American tribes, see Nott and Gliddon, 'Types of Mankind,' 1854, p. 440; Prichard, 'Physical History of Mankind,' vol. i. 3rd ed. p. 321; on the natives of Arakhan, ibid. vol. iv. p. 537. Wilson, 'Physical Ethnology,' Smithsonian Institution, 1863, p. 288; on the Fijians, p. 290. Sir J. Lubbock ('Prehistoric Times,' 2nd ed. 1869, p. 506) gives an excellent resume on this subject.) As with the skull, so with the nose; the ancient Huns during the age of Attila were accustomed to flatten the noses of their infants with bandages, "for the sake of exaggerating a natural conformation." With the Tahitians, to be called LONG-NOSE is considered as an insult, and they compress the noses and foreheads of their children for the sake of beauty. The same holds with the Malays of Sumatra, the Hottentots, certain Negroes, and the natives of Brazil. (71. On the Huns, Godron, 'De l'Espèce,' tom. ii. 1859, p. 300. On the Tahitians, Waitz, 'Anthropology,' Eng. translat. vol. i. p. 305. Marsden, quoted by Prichard, 'Phys. Hist. of Mankind,' 3rd edit. vol. v. p. 67. Lawrence, 'Lectures on Physiology,' p. 337.) The Chinese have by nature unusually small feet (72. This fact was ascertained in the 'Reise der Novara: Anthropolog. Theil.' Dr. Weisbach, 1867, s. 265.); and it is well known that the women of the upper classes distort their feet to make them still smaller. Lastly, Humboldt thinks that the American Indians prefer colouring their bodies with red paint in order to exaggerate their natural tint; and until recently European women added to their naturally bright colours by rouge and white cosmetics; but it may be doubted whether barbarous nations have generally had any such intention in painting themselves. In the fashions of our own dress we see exactly the same principle and the same desire to carry every point to an extreme; we exhibit, also, the same spirit of emulation. But the fashions of savages are far more permanent than ours; and whenever their bodies are artificially modified, this is necessarily the case. The Arab women of the Upper Nile occupy about three days in dressing their hair; they never imitate other tribes, "but simply vie with each other in the superlativeness of their own style." Dr. Wilson, in speaking of the compressed skulls of various American races, adds, "such usages are among the least eradicable, and long survive the shock of revolutions that change dynasties and efface more important national peculiarities." (73. 'Smithsonian Institution,' 1863, p. 289. On the fashions of Arab women, Sir S. Baker, 'The Nile Tributaries,' 1867, p. 121.) The same principle comes into play in the art of breeding; and we can thus understand, as I have elsewhere explained (74. The 'Variation of Animals and Plants under Domestication,' vol. i. p. 214; vol. ii. p. 240.), the wonderful development of the many races of animals and plants, which have been kept merely for ornament. Fanciers always wish each character to be somewhat increased; they do not admire a medium standard; they certainly do not desire any great and abrupt change in the character of their breeds; they admire solely what they are accustomed to, but they ardently desire to see each characteristic feature a little more developed. The senses of man and of the lower animals seem to be so constituted that brilliant colours and certain forms, as well as harmonious and rhythmical sounds, give pleasure and are called beautiful; but why this should be so we know not. It is certainly not true that there is in the mind of man any universal standard of beauty with respect to the human body. It is, however, possible that certain tastes may in the course of time become inherited, though there is no evidence in favour of this belief: and if so, each race would possess its own innate ideal standard of beauty. It has been argued (75. Schaaffhausen, 'Archiv. für Anthropologie,' 1866, s. 164.) that ugliness consists in an approach to the structure of the lower animals, and no doubt this is partly true with the more civilised nations, in which intellect is highly appreciated; but this explanation will hardly apply to all forms of ugliness. The men of each race prefer what they are accustomed to; they cannot endure any great change; but they like variety, and admire each characteristic carried to a moderate extreme. (76. Mr. Bain has collected ('Mental and Moral Science,' 1868, pp. 304-314) about a dozen more or less different theories of the idea of beauty; but none is quite the same as that here given.) Men accustomed to a nearly oval face, to straight and regular features, and to bright colours, admire, as we Europeans know, these points when strongly developed. On the other hand, men accustomed to a broad face, with high cheek-bones, a depressed nose, and a black skin, admire these peculiarities when strongly marked. No doubt characters of all kinds may be too much developed for beauty. Hence a perfect beauty, which implies many characters modified in a particular manner, will be in every race a prodigy. As the great anatomist Bichat long ago said, if every one were cast in the same mould, there would be no such thing as beauty. If all our women were to become as beautiful as the Venus de' Medici, we should for a time be charmed; but we should soon wish for variety; and as soon as we had obtained variety, we should wish to see certain characters a little exaggerated beyond the then existing common standard. CHAPTER XX. SECONDARY SEXUAL CHARACTERS OF MAN--continued. On the effects of the continued selection of women according to a different standard of beauty in each race--On the causes which interfere with sexual selection in civilised and savage nations--Conditions favourable to sexual selection during primeval times--On the manner of action of sexual selection with mankind--On the women in savage tribes having some power to choose their husbands--Absence of hair on the body, and development of the beard--Colour of the skin--Summary. We have seen in the last chapter that with all barbarous races ornaments, dress, and external appearance are highly valued; and that the men judge of the beauty of their women by widely different standards. We must next inquire whether this preference and the consequent selection during many generations of those women, which appear to the men of each race the most attractive, has altered the character either of the females alone, or of both sexes. With mammals the general rule appears to be that characters of all kinds are inherited equally by the males and females; we might therefore expect that with mankind any characters gained by the females or by the males through sexual selection would commonly be transferred to the offspring of both sexes. If any change has thus been effected, it is almost certain that the different races would be differently modified, as each has its own standard of beauty. With mankind, especially with savages, many causes interfere with the action of sexual selection as far as the bodily frame is concerned. Civilised men are largely attracted by the mental charms of women, by their wealth, and especially by their social position; for men rarely marry into a much lower rank. The men who succeed in obtaining the more beautiful women will not have a better chance of leaving a long line of descendants than other men with plainer wives, save the few who bequeath their fortunes according to primogeniture. With respect to the opposite form of selection, namely, of the more attractive men by the women, although in civilised nations women have free or almost free choice, which is not the case with barbarous races, yet their choice is largely influenced by the social position and wealth of the men; and the success of the latter in life depends much on their intellectual powers and energy, or on the fruits of these same powers in their forefathers. No excuse is needed for treating this subject in some detail; for, as the German philosopher Schopenhauer remarks, "the final aim of all love intrigues, be they comic or tragic, is really of more importance than all other ends in human life. What it all turns upon is nothing less than the composition of the next generation...It is not the weal or woe of any one individual, but that of the human race to come, which is here at stake." (1. 'Schopenhauer and Darwinism,' in 'Journal of Anthropology,' Jan. 1871, p. 323. There is, however, reason to believe that in certain civilised and semi-civilised nations sexual selection has effected something in modifying the bodily frame of some of the members. Many persons are convinced, as it appears to me with justice, that our aristocracy, including under this term all wealthy families in which primogeniture has long prevailed, from having chosen during many generations from all classes the more beautiful women as their wives, have become handsomer, according to the European standard, than the middle classes; yet the middle classes are placed under equally favourable conditions of life for the perfect development of the body. Cook remarks that the superiority in personal appearance "which is observable in the erees or nobles in all the other islands (of the Pacific) is found in the Sandwich Islands"; but this may be chiefly due to their better food and manner of life. The old traveller Chardin, in describing the Persians, says their "blood is now highly refined by frequent intermixtures with the Georgians and Circassians, two nations which surpass all the world in personal beauty. There is hardly a man of rank in Persia who is not born of a Georgian or Circassian mother." He adds that they inherit their beauty, "not from their ancestors, for without the above mixture, the men of rank in Persia, who are descendants of the Tartars, would be extremely ugly." (2. These quotations are taken from Lawrence ('Lectures on Physiology,' etc., 1822, p. 393), who attributes the beauty of the upper classes in England to the men having long selected the more beautiful women.) Here is a more curious case; the priestesses who attended the temple of Venus Erycina at San-Giuliano in Sicily, were selected for their beauty out of the whole of Greece; they were not vestal virgins, and Quatrefages (3. 'Anthropologie,' 'Revue des Cours Scientifiques,' Oct. 1868, p. 721.), who states the foregoing fact, says that the women of San-Giuliano are now famous as the most beautiful in the island, and are sought by artists as models. But it is obvious that the evidence in all the above cases is doubtful. The following case, though relating to savages, is well worth giving for its curiosity. Mr. Winwood Reade informs me that the Jollofs, a tribe of negroes on the west coast of Africa, "are remarkable for their uniformly fine appearance." A friend of his asked one of these men, "How is it that every one whom I meet is so fine looking, not only your men but your women?" The Jollof answered, "It is very easily explained: it has always been our custom to pick out our worst-looking slaves and to sell them." It need hardly be added that with all savages, female slaves serve as concubines. That this negro should have attributed, whether rightly or wrongly, the fine appearance of his tribe to the long-continued elimination of the ugly women is not so surprising as it may at first appear; for I have elsewhere shewn (4. 'Variation of Animals and Plants under Domestication,' vol. i. p. 207.) that negroes fully appreciate the importance of selection in the breeding of their domestic animals, and I could give from Mr. Reade additional evidence on this head. THE CAUSES WHICH PREVENT OR CHECK THE ACTION OF SEXUAL SELECTION WITH SAVAGES. The chief causes are, first, so-called communal marriages or promiscuous intercourse; secondly, the consequences of female infanticide; thirdly, early betrothals; and lastly, the low estimation in which women are held, as mere slaves. These four points must be considered in some detail. It is obvious that as long as the pairing of man, or of any other animal, is left to mere chance, with no choice exerted by either sex, there can be no sexual selection; and no effect will be produced on the offspring by certain individuals having had an advantage over others in their courtship. Now it is asserted that there exist at the present day tribes which practise what Sir J. Lubbock by courtesy calls communal marriages; that is, all the men and women in the tribe are husbands and wives to one another. The licentiousness of many savages is no doubt astonishing, but it seems to me that more evidence is requisite, before we fully admit that their intercourse is in any case promiscuous. Nevertheless all those who have most closely studied the subject (5. Sir J. Lubbock, 'The Origin of Civilisation,' 1870, chap. iii. especially pp. 60-67. Mr. M'Lennan, in his extremely valuable work on 'Primitive Marriage,' 1865, p. 163, speaks of the union of the sexes "in the earliest times as loose, transitory, and in some degree promiscuous." Mr. M'Lennan and Sir J. Lubbock have collected much evidence on the extreme licentiousness of savages at the present time. Mr. L.H. Morgan, in his interesting memoir of the classificatory system of relationship. ('Proceedings of the American Academy of Sciences,' vol. vii. Feb. 1868, p. 475), concludes that polygamy and all forms of marriage during primeval times were essentially unknown. It appears also, from Sir J. Lubbock's work, that Bachofen likewise believes that communal intercourse originally prevailed.), and whose judgment is worth much more than mine, believe that communal marriage (this expression being variously guarded) was the original and universal form throughout the world, including therein the intermarriage of brothers and sisters. The late Sir A. Smith, who had travelled widely in S. Africa, and knew much about the habits of savages there and elsewhere, expressed to me the strongest opinion that no race exists in which woman is considered as the property of the community. I believe that his judgment was largely determined by what is implied by the term marriage. Throughout the following discussion I use the term in the same sense as when naturalists speak of animals as monogamous, meaning thereby that the male is accepted by or chooses a single female, and lives with her either during the breeding-season or for the whole year, keeping possession of her by the law of might; or, as when they speak of a polygamous species, meaning that the male lives with several females. This kind of marriage is all that concerns us here, as it suffices for the work of sexual selection. But I know that some of the writers above referred to imply by the term marriage a recognised right protected by the tribe. The indirect evidence in favour of the belief of the former prevalence of communal marriages is strong, and rests chiefly on the terms of relationship which are employed between the members of the same tribe, implying a connection with the tribe, and not with either parent. But the subject is too large and complex for even an abstract to be here given, and I will confine myself to a few remarks. It is evident in the case of such marriages, or where the marriage tie is very loose, that the relationship of the child to its father cannot be known. But it seems almost incredible that the relationship of the child to its mother should ever be completely ignored, especially as the women in most savage tribes nurse their infants for a long time. Accordingly, in many cases the lines of descent are traced through the mother alone, to the exclusion of the father. But in other cases the terms employed express a connection with the tribe alone, to the exclusion even of the mother. It seems possible that the connection between the related members of the same barbarous tribe, exposed to all sorts of danger, might be so much more important, owing to the need of mutual protection and aid, than that between the mother and her child, as to lead to the sole use of terms expressive of the former relationships; but Mr. Morgan is convinced that this view is by no means sufficient. The terms of relationship used in different parts of the world may be divided, according to the author just quoted, into two great classes, the classificatory and descriptive, the latter being employed by us. It is the classificatory system which so strongly leads to the belief that communal and other extremely loose forms of marriage were originally universal. But as far as I can see, there is no necessity on this ground for believing in absolutely promiscuous intercourse; and I am glad to find that this is Sir J. Lubbock's view. Men and women, like many of the lower animals, might formerly have entered into strict though temporary unions for each birth, and in this case nearly as much confusion would have arisen in the terms of relationship as in the case of promiscuous intercourse. As far as sexual selection is concerned, all that is required is that choice should be exerted before the parents unite, and it signifies little whether the unions last for life or only for a season. Besides the evidence derived from the terms of relationship, other lines of reasoning indicate the former wide prevalence of communal marriage. Sir J. Lubbock accounts for the strange and widely-extended habit of exogamy--that is, the men of one tribe taking wives from a distinct tribe,--by communism having been the original form of intercourse; so that a man never obtained a wife for himself unless he captured her from a neighbouring and hostile tribe, and then she would naturally have become his sole and valuable property. Thus the practice of capturing wives might have arisen; and from the honour so gained it might ultimately have become the universal habit. According to Sir J. Lubbock (6. 'Address to British Association On the Social and Religious Condition of the Lower Races of Man,' 1870, p. 20.), we can also thus understand "the necessity of expiation for marriage as an infringement of tribal rites, since according to old ideas, a man had no right to appropriate to himself that which belonged to the whole tribe." Sir J. Lubbock further gives a curious body of facts shewing that in old times high honour was bestowed on women who were utterly licentious; and this, as he explains, is intelligible, if we admit that promiscuous intercourse was the aboriginal, and therefore long revered custom of the tribe. (7. 'Origin of Civilisation,' 1870, p. 86. In the several works above quoted, there will be found copious evidence on relationship through the females alone, or with the tribe alone.) Although the manner of development of the marriage tie is an obscure subject, as we may infer from the divergent opinions on several points between the three authors who have studied it most closely, namely, Mr. Morgan, Mr. M'Lennan, and Sir J. Lubbock, yet from the foregoing and several other lines of evidence it seems probable (8. Mr. C. Staniland Wake argues strongly ('Anthropologia,' March, 1874, p. 197) against the views held by these three writers on the former prevalence of almost promiscuous intercourse; and he thinks that the classificatory system of relationship can be otherwise explained.) that the habit of marriage, in any strict sense of the word, has been gradually developed; and that almost promiscuous or very loose intercourse was once extremely common throughout the world. Nevertheless, from the strength of the feeling of jealousy all through the animal kingdom, as well as from the analogy of the lower animals, more particularly of those which come nearest to man, I cannot believe that absolutely promiscuous intercourse prevailed in times past, shortly before man attained to his present rank in the zoological scale. Man, as I have attempted to shew, is certainly descended from some ape-like creature. With the existing Quadrumana, as far as their habits are known, the males of some species are monogamous, but live during only a part of the year with the females: of this the orang seems to afford an instance. Several kinds, for example some of the Indian and American monkeys, are strictly monogamous, and associate all the year round with their wives. Others are polygamous, for example the gorilla and several American species, and each family lives separate. Even when this occurs, the families inhabiting the same district are probably somewhat social; the chimpanzee, for instance, is occasionally met with in large bands. Again, other species are polygamous, but several males, each with his own females, live associated in a body, as with several species of baboons. (9. Brehm ('Thierleben,' B. i. p. 77) says Cynocephalus hamadryas lives in great troops containing twice as many adult females as adult males. See Rengger on American polygamous species, and Owen ('Anatomy of Vertebrates,' vol. iii. p. 746) on American monogamous species. Other references might be added.) We may indeed conclude from what we know of the jealousy of all male quadrupeds, armed, as many of them are, with special weapons for battling with their rivals, that promiscuous intercourse in a state of nature is extremely improbable. The pairing may not last for life, but only for each birth; yet if the males which are the strongest and best able to defend or otherwise assist their females and young, were to select the more attractive females, this would suffice for sexual selection. Therefore, looking far enough back in the stream of time, and judging from the social habits of man as he now exists, the most probable view is that he aboriginally lived in small communities, each with a single wife, or if powerful with several, whom he jealously guarded against all other men. Or he may not have been a social animal, and yet have lived with several wives, like the gorilla; for all the natives "agree that but one adult male is seen in a band; when the young male grows up, a contest takes place for mastery, and the strongest, by killing and driving out the others, establishes himself as the head of the community." (10. Dr. Savage, in 'Boston Journal of Natural History,' vol. v. 1845-47, p. 423.) The younger males, being thus expelled and wandering about, would, when at last successful in finding a partner, prevent too close interbreeding within the limits of the same family. Although savages are now extremely licentious, and although communal marriages may formerly have largely prevailed, yet many tribes practise some form of marriage, but of a far more lax nature than that of civilised nations. Polygamy, as just stated, is almost universally followed by the leading men in every tribe. Nevertheless there are tribes, standing almost at the bottom of the scale, which are strictly monogamous. This is the case with the Veddahs of Ceylon: they have a saying, according to Sir J. Lubbock (11. 'Prehistoric Times,' 1869, p. 424.), "that death alone can separate husband and wife." An intelligent Kandyan chief, of course a polygamist, "was perfectly scandalised at the utter barbarism of living with only one wife, and never parting until separated by death." It was, he said, "just like the Wanderoo monkeys." Whether savages who now enter into some form of marriage, either polygamous or monogamous, have retained this habit from primeval times, or whether they have returned to some form of marriage, after passing through a stage of promiscuous intercourse, I will not pretend to conjecture. INFANTICIDE. This practice is now very common throughout the world, and there is reason to believe that it prevailed much more extensively during former times. (12. Mr. M'Lennan, 'Primitive Marriage,' 1865. See especially on exogamy and infanticide, pp. 130, 138, 165.) Barbarians find it difficult to support themselves and their children, and it is a simple plan to kill their infants. In South America some tribes, according to Azara, formerly destroyed so many infants of both sexes that they were on the point of extinction. In the Polynesian Islands women have been known to kill from four or five, to even ten of their children; and Ellis could not find a single woman who had not killed at least one. In a village on the eastern frontier of India Colonel MacCulloch found not a single female child. Wherever infanticide (13. Dr. Gerland ('Ueber das Aussterben der Naturvölker,' 1868) has collected much information on infanticide, see especially ss. 27, 51, 54. Azara ('Voyages,' etc., tom. ii. pp. 94, 116) enters in detail on the motives. See also M'Lennan (ibid. p. 139) for cases in India. In the former reprints of the 2nd edition of this book an incorrect quotation from Sir G. Grey was unfortunately given in the above passage and has now been removed from the text.) prevails the struggle for existence will be in so far less severe, and all the members of the tribe will have an almost equally good chance of rearing their few surviving children. In most cases a larger number of female than of male infants are destroyed, for it is obvious that the latter are of more value to the tribe, as they will, when grown up, aid in defending it, and can support themselves. But the trouble experienced by the women in rearing children, their consequent loss of beauty, the higher estimation set on them when few, and their happier fate, are assigned by the women themselves, and by various observers, as additional motives for infanticide. When, owing to female infanticide, the women of a tribe were few, the habit of capturing wives from neighbouring tribes would naturally arise. Sir J. Lubbock, however, as we have seen, attributes the practice in chief part to the former existence of communal marriage, and to the men having consequently captured women from other tribes to hold as their sole property. Additional causes might be assigned, such as the communities being very small, in which case, marriageable women would often be deficient. That the habit was most extensively practised during former times, even by the ancestors of civilised nations, is clearly shewn by the preservation of many curious customs and ceremonies, of which Mr. M'Lennan has given an interesting account. In our own marriages the "best man" seems originally to have been the chief abettor of the bridegroom in the act of capture. Now as long as men habitually procured their wives through violence and craft, they would have been glad to seize on any woman, and would not have selected the more attractive ones. But as soon as the practice of procuring wives from a distinct tribe was effected through barter, as now occurs in many places, the more attractive women would generally have been purchased. The incessant crossing, however, between tribe and tribe, which necessarily follows from any form of this habit, would tend to keep all the people inhabiting the same country nearly uniform in character; and this would interfere with the power of sexual selection in differentiating the tribes. The scarcity of women, consequent on female infanticide, leads, also, to another practice, that of polyandry, still common in several parts of the world, and which formerly, as Mr. M'Lennan believes, prevailed almost universally: but this latter conclusion is doubted by Mr. Morgan and Sir J. Lubbock. (14. 'Primitive Marriage,' p. 208; Sir J. Lubbock, 'Origin of Civilisation,' p. 100. See also Mr. Morgan, loc. cit., on the former prevalence of polyandry.) Whenever two or more men are compelled to marry one woman, it is certain that all the women of the tribe will get married, and there will be no selection by the men of the more attractive women. But under these circumstances the women no doubt will have the power of choice, and will prefer the more attractive men. Azara, for instance, describes how carefully a Guana woman bargains for all sorts of privileges, before accepting some one or more husbands; and the men in consequence take unusual care of their personal appearance. So amongst the Todas of India, who practise polyandry, the girls can accept or refuse any man. (15. Azara, 'Voyages,' etc., tom. ii. pp. 92-95; Colonel Marshall, 'Amongst the Todas,' p. 212.) A very ugly man in these cases would perhaps altogether fail in getting a wife, or get one later in life; but the handsomer men, although more successful in obtaining wives, would not, as far as we can see, leave more offspring to inherit their beauty than the less handsome husbands of the same women. EARLY BETROTHALS AND SLAVERY OF WOMEN. With many savages it is the custom to betroth the females whilst mere infants; and this would effectually prevent preference being exerted on either side according to personal appearance. But it would not prevent the more attractive women from being afterwards stolen or taken by force from their husbands by the more powerful men; and this often happens in Australia, America, and elsewhere. The same consequences with reference to sexual selection would to a certain extent follow, when women are valued almost solely as slaves or beasts of burden, as is the case with many savages. The men, however, at all times would prefer the handsomest slaves according to their standard of beauty. We thus see that several customs prevail with savages which must greatly interfere with, or completely stop, the action of sexual selection. On the other hand, the conditions of life to which savages are exposed, and some of their habits, are favourable to natural selection; and this comes into play at the same time with sexual selection. Savages are known to suffer severely from recurrent famines; they do not increase their food by artificial means; they rarely refrain from marriage (16. Burchell says ('Travels in S. Africa,' vol. ii. 1824, p. 58), that among the wild nations of Southern Africa, neither men nor women ever pass their lives in a state of celibacy. Azara ('Voyages dans l'Amérique Merid.' tom. ii. 1809, p. 21) makes precisely the same remark in regard to the wild Indians of South America.), and generally marry whilst young. Consequently they must be subjected to occasional hard struggles for existence, and the favoured individuals will alone survive. At a very early period, before man attained to his present rank in the scale, many of his conditions would be different from what now obtains amongst savages. Judging from the analogy of the lower animals, he would then either live with a single female, or be a polygamist. The most powerful and able males would succeed best in obtaining attractive females. They would also succeed best in the general struggle for life, and in defending their females, as well as their offspring, from enemies of all kinds. At this early period the ancestors of man would not be sufficiently advanced in intellect to look forward to distant contingencies; they would not foresee that the rearing of all their children, especially their female children, would make the struggle for life severer for the tribe. They would be governed more by their instincts and less by their reason than are savages at the present day. They would not at that period have partially lost one of the strongest of all instincts, common to all the lower animals, namely the love of their young offspring; and consequently they would not have practised female infanticide. Women would not have been thus rendered scarce, and polyandry would not have been practised; for hardly any other cause, except the scarcity of women seems sufficient to break down the natural and widely prevalent feeling of jealousy, and the desire of each male to possess a female for himself. Polyandry would be a natural stepping-stone to communal marriages or almost promiscuous intercourse; though the best authorities believe that this latter habit preceded polyandry. During primordial times there would be no early betrothals, for this implies foresight. Nor would women be valued merely as useful slaves or beasts of burthen. Both sexes, if the females as well as the males were permitted to exert any choice, would choose their partners not for mental charms, or property, or social position, but almost solely from external appearance. All the adults would marry or pair, and all the offspring, as far as that was possible, would be reared; so that the struggle for existence would be periodically excessively severe. Thus during these times all the conditions for sexual selection would have been more favourable than at a later period, when man had advanced in his intellectual powers but had retrograded in his instincts. Therefore, whatever influence sexual selection may have had in producing the differences between the races of man, and between man and the higher Quadrumana, this influence would have been more powerful at a remote period than at the present day, though probably not yet wholly lost. THE MANNER OF ACTION OF SEXUAL SELECTION WITH MANKIND. With primeval man under the favourable conditions just stated, and with those savages who at the present time enter into any marriage tie, sexual selection has probably acted in the following manner, subject to greater or less interference from female infanticide, early betrothals, etc. The strongest and most vigorous men--those who could best defend and hunt for their families, who were provided with the best weapons and possessed the most property, such as a large number of dogs or other animals,--would succeed in rearing a greater average number of offspring than the weaker and poorer members of the same tribes. There can, also, be no doubt that such men would generally be able to select the more attractive women. At present the chiefs of nearly every tribe throughout the world succeed in obtaining more than one wife. I hear from Mr. Mantell that, until recently, almost every girl in New Zealand who was pretty, or promised to be pretty, was tapu to some chief. With the Kafirs, as Mr. C. Hamilton states (17. 'Anthropological Review,' Jan. 1870, p. xvi.), "the chiefs generally have the pick of the women for many miles round, and are most persevering in establishing or confirming their privilege." We have seen that each race has its own style of beauty, and we know that it is natural to man to admire each characteristic point in his domestic animals, dress, ornaments, and personal appearance, when carried a little beyond the average. If then the several foregoing propositions be admitted, and I cannot see that they are doubtful, it would be an inexplicable circumstance if the selection of the more attractive women by the more powerful men of each tribe, who would rear on an average a greater number of children, did not after the lapse of many generations somewhat modify the character of the tribe. When a foreign breed of our domestic animals is introduced into a new country, or when a native breed is long and carefully attended to, either for use or ornament, it is found after several generations to have undergone a greater or less amount of change whenever the means of comparison exist. This follows from unconscious selection during a long series of generations--that is, the preservation of the most approved individuals--without any wish or expectation of such a result on the part of the breeder. So again, if during many years two careful breeders rear animals of the same family, and do not compare them together or with a common standard, the animals are found to have become, to the surprise of their owners, slightly different. (18. The 'Variation of Animals and Plants under Domestication,' vol. ii. pp. 210-217.) Each breeder has impressed, as von Nathusius well expresses it, the character of his own mind--his own taste and judgment--on his animals. What reason, then, can be assigned why similar results should not follow from the long-continued selection of the most admired women by those men of each tribe who were able to rear the greatest number of children? This would be unconscious selection, for an effect would be produced, independently of any wish or expectation on the part of the men who preferred certain women to others. Let us suppose the members of a tribe, practising some form of marriage, to spread over an unoccupied continent, they would soon split up into distinct hordes, separated from each other by various barriers, and still more effectually by the incessant wars between all barbarous nations. The hordes would thus be exposed to slightly different conditions and habits of life, and would sooner or later come to differ in some small degree. As soon as this occurred, each isolated tribe would form for itself a slightly different standard of beauty (19. An ingenious writer argues, from a comparison of the pictures of Raphael, Rubens, and modern French artists, that the idea of beauty is not absolutely the same even throughout Europe: see the 'Lives of Haydn and Mozart,' by Bombet (otherwise M. Beyle), English translation, p. 278.); and then unconscious selection would come into action through the more powerful and leading men preferring certain women to others. Thus the differences between the tribes, at first very slight, would gradually and inevitably be more or less increased. With animals in a state of nature, many characters proper to the males, such as size, strength, special weapons, courage and pugnacity, have been acquired through the law of battle. The semi-human progenitors of man, like their allies the Quadrumana, will almost certainly have been thus modified; and, as savages still fight for the possession of their women, a similar process of selection has probably gone on in a greater or less degree to the present day. Other characters proper to the males of the lower animals, such as bright colours and various ornaments, have been acquired by the more attractive males having been preferred by the females. There are, however, exceptional cases in which the males are the selectors, instead of having been the selected. We recognise such cases by the females being more highly ornamented than the males,--their ornamental characters having been transmitted exclusively or chiefly to their female offspring. One such case has been described in the order to which man belongs, that of the Rhesus monkey. Man is more powerful in body and mind than woman, and in the savage state he keeps her in a far more abject state of bondage than does the male of any other animal; therefore it is not surprising that he should have gained the power of selection. Women are everywhere conscious of the value of their own beauty; and when they have the means, they take more delight in decorating themselves with all sorts of ornaments than do men. They borrow the plumes of male birds, with which nature has decked this sex, in order to charm the females. As women have long been selected for beauty, it is not surprising that some of their successive variations should have been transmitted exclusively to the same sex; consequently that they should have transmitted beauty in a somewhat higher degree to their female than to their male offspring, and thus have become more beautiful, according to general opinion, than men. Women, however, certainly transmit most of their characters, including some beauty, to their offspring of both sexes; so that the continued preference by the men of each race for the more attractive women, according to their standard of taste, will have tended to modify in the same manner all the individuals of both sexes belonging to the race. With respect to the other form of sexual selection (which with the lower animals is much the more common), namely, when the females are the selectors, and accept only those males which excite or charm them most, we have reason to believe that it formerly acted on our progenitors. Man in all probability owes his beard, and perhaps some other characters, to inheritance from an ancient progenitor who thus gained his ornaments. But this form of selection may have occasionally acted during later times; for in utterly barbarous tribes the women have more power in choosing, rejecting, and tempting their lovers, or of afterwards changing their husbands, than might have been expected. As this is a point of some importance, I will give in detail such evidence as I have been able to collect. Hearne describes how a woman in one of the tribes of Arctic America repeatedly ran away from her husband and joined her lover; and with the Charruas of S. America, according to Azara, divorce is quite optional. Amongst the Abipones, a man on choosing a wife bargains with the parents about the price. But "it frequently happens that the girl rescinds what has been agreed upon between the parents and the bridegroom, obstinately rejecting the very mention of marriage." She often runs away, hides herself, and thus eludes the bridegroom. Captain Musters who lived with the Patagonians, says that their marriages are always settled by inclination; "if the parents make a match contrary to the daughter's will, she refuses and is never compelled to comply." In Tierra del Fuego a young man first obtains the consent of the parents by doing them some service, and then he attempts to carry off the girl; "but if she is unwilling, she hides herself in the woods until her admirer is heartily tired of looking for her, and gives up the pursuit; but this seldom happens." In the Fiji Islands the man seizes on the woman whom he wishes for his wife by actual or pretended force; but "on reaching the home of her abductor, should she not approve of the match, she runs to some one who can protect her; if, however, she is satisfied, the matter is settled forthwith." With the Kalmucks there is a regular race between the bride and bridegroom, the former having a fair start; and Clarke "was assured that no instance occurs of a girl being caught, unless she has a partiality to the pursuer." Amongst the wild tribes of the Malay Archipelago there is also a racing match; and it appears from M. Bourien's account, as Sir J. Lubbock remarks, that "the race, 'is not to the swift, nor the battle to the strong,' but to the young man who has the good fortune to please his intended bride." A similar custom, with the same result, prevails with the Koraks of North-Eastern Asia. Turning to Africa: the Kafirs buy their wives, and girls are severely beaten by their fathers if they will not accept a chosen husband; but it is manifest from many facts given by the Rev. Mr. Shooter, that they have considerable power of choice. Thus very ugly, though rich men, have been known to fail in getting wives. The girls, before consenting to be betrothed, compel the men to shew themselves off first in front and then behind, and "exhibit their paces." They have been known to propose to a man, and they not rarely run away with a favoured lover. So again, Mr. Leslie, who was intimately acquainted with the Kafirs, says, "it is a mistake to imagine that a girl is sold by her father in the same manner, and with the same authority, with which he would dispose of a cow." Amongst the degraded Bushmen of S. Africa, "when a girl has grown up to womanhood without having been betrothed, which, however, does not often happen, her lover must gain her approbation, as well as that of the parents." (20. Azara, 'Voyages,' etc., tom. ii. p. 23. Dobrizhoffer, 'An Account of the Abipones,' vol. ii. 1822, p. 207. Capt. Musters, in 'Proc. R. Geograph. Soc.' vol. xv. p. 47. Williams on the Fiji Islanders, as quoted by Lubbock, 'Origin of Civilisation,' 1870, p. 79. On the Fuegians, King and Fitzroy, 'Voyages of the "Adventure" and "Beagle,"' vol. ii. 1839, p. 182. On the Kalmucks, quoted by M'Lennan, 'Primitive Marriage,' 1865, p. 32. On the Malays, Lubbock, ibid. p. 76. The Rev. J. Shooter, 'On the Kafirs of Natal,' 1857, pp. 52-60. Mr. D. Leslie, 'Kafir Character and Customs,' 1871, p. 4. On the Bush-men, Burchell, 'Travels in S. Africa,' ii. 1824, p. 59. On the Koraks by McKennan, as quoted by Mr. Wake, in 'Anthropologia,' Oct. 1873, p. 75.) Mr. Winwood Reade made inquiries for me with respect to the negroes of Western Africa, and he informs me that "the women, at least among the more intelligent Pagan tribes, have no difficulty in getting the husbands whom they may desire, although it is considered unwomanly to ask a man to marry them. They are quite capable of falling in love, and of forming tender, passionate, and faithful attachments." Additional cases could be given. We thus see that with savages the women are not in quite so abject a state in relation to marriage as has often been supposed. They can tempt the men whom they prefer, and can sometimes reject those whom they dislike, either before or after marriage. Preference on the part of the women, steadily acting in any one direction, would ultimately affect the character of the tribe; for the women would generally choose not merely the handsomest men, according to their standard of taste, but those who were at the same time best able to defend and support them. Such well-endowed pairs would commonly rear a larger number of offspring than the less favoured. The same result would obviously follow in a still more marked manner if there was selection on both sides; that is, if the more attractive, and at the same time more powerful men were to prefer, and were preferred by, the more attractive women. And this double form of selection seems actually to have occurred, especially during the earlier periods of our long history. We will now examine a little more closely some of the characters which distinguish the several races of man from one another and from the lower animals, namely, the greater or less deficiency of hair on the body, and the colour of the skin. We need say nothing about the great diversity in the shape of the features and of the skull between the different races, as we have seen in the last chapter how different is the standard of beauty in these respects. These characters will therefore probably have been acted on through sexual selection; but we have no means of judging whether they have been acted on chiefly from the male or female side. The musical faculties of man have likewise been already discussed. ABSENCE OF HAIR ON THE BODY, AND ITS DEVELOPMENT ON THE FACE AND HEAD. From the presence of the woolly hair or lanugo on the human foetus, and of rudimentary hairs scattered over the body during maturity, we may infer that man is descended from some animal which was born hairy and remained so during life. The loss of hair is an inconvenience and probably an injury to man, even in a hot climate, for he is thus exposed to the scorching of the sun, and to sudden chills, especially during wet weather. As Mr. Wallace remarks, the natives in all countries are glad to protect their naked backs and shoulders with some slight covering. No one supposes that the nakedness of the skin is any direct advantage to man; his body therefore cannot have been divested of hair through natural selection. (21. 'Contributions to the Theory of Natural Selection,' 1870, p. 346. Mr. Wallace believes (p. 350) "that some intelligent power has guided or determined the development of man"; and he considers the hairless condition of the skin as coming under this head. The Rev. T.R. Stebbing, in commenting on this view ('Transactions of Devonshire Association for Science,' 1870) remarks, that had Mr. Wallace "employed his usual ingenuity on the question of man's hairless skin, he might have seen the possibility of its selection through its superior beauty or the health attaching to superior cleanliness.") Nor, as shewn in a former chapter, have we any evidence that this can be due to the direct action of climate, or that it is the result of correlated development. The absence of hair on the body is to a certain extent a secondary sexual character; for in all parts of the world women are less hairy than men. Therefore we may reasonably suspect that this character has been gained through sexual selection. We know that the faces of several species of monkeys, and large surfaces at the posterior end of the body of other species, have been denuded of hair; and this we may safely attribute to sexual selection, for these surfaces are not only vividly coloured, but sometimes, as with the male mandrill and female rhesus, much more vividly in the one sex than in the other, especially during the breeding-season. I am informed by Mr. Bartlett that, as these animals gradually reach maturity, the naked surfaces grow larger compared with the size of their bodies. The hair, however, appears to have been removed, not for the sake of nudity, but that the colour of the skin may be more fully displayed. So again with many birds, it appears as if the head and neck had been divested of feathers through sexual selection, to exhibit the brightly-coloured skin. As the body in woman is less hairy than in man, and as this character is common to all races, we may conclude that it was our female semi-human ancestors who were first divested of hair, and that this occurred at an extremely remote period before the several races had diverged from a common stock. Whilst our female ancestors were gradually acquiring this new character of nudity, they must have transmitted it almost equally to their offspring of both sexes whilst young; so that its transmission, as with the ornaments of many mammals and birds, has not been limited either by sex or age. There is nothing surprising in a partial loss of hair having been esteemed as an ornament by our ape-like progenitors, for we have seen that innumerable strange characters have been thus esteemed by animals of all kinds, and have consequently been gained through sexual selection. Nor is it surprising that a slightly injurious character should have been thus acquired; for we know that this is the case with the plumes of certain birds, and with the horns of certain stags. The females of some of the anthropoid apes, as stated in a former chapter, are somewhat less hairy on the under surface than the males; and here we have what might have afforded a commencement for the process of denudation. With respect to the completion of the process through sexual selection, it is well to bear in mind the New Zealand proverb, "There is no woman for a hairy man." All who have seen photographs of the Siamese hairy family will admit how ludicrously hideous is the opposite extreme of excessive hairiness. And the king of Siam had to bribe a man to marry the first hairy woman in the family; and she transmitted this character to her young offspring of both sexes. (22. The 'Variation of Animals and Plants under Domestication,' vol. ii. 1868, p. 237.) Some races are much more hairy than others, especially the males; but it must not be assumed that the more hairy races, such as the European, have retained their primordial condition more completely than the naked races, such as the Kalmucks or Americans. It is more probable that the hairiness of the former is due to partial reversion; for characters which have been at some former period long inherited are always apt to return. We have seen that idiots are often very hairy, and they are apt to revert in other characters to a lower animal type. It does not appear that a cold climate has been influential in leading to this kind of reversion; excepting perhaps with the negroes, who have been reared during several generations in the United States (23. 'Investigations into Military and Anthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p. 568:--Observations were carefully made on the hairiness of 2129 black and coloured soldiers, whilst they were bathing; and by looking to the published table, "it is manifest at a glance that there is but little, if any, difference between the white and the black races in this respect." It is, however, certain that negroes in their native and much hotter land of Africa, have remarkably smooth bodies. It should be particularly observed, that both pure blacks and mulattoes were included in the above enumeration; and this is an unfortunate circumstance, as in accordance with a principle, the truth of which I have elsewhere proved, crossed races of man would be eminently liable to revert to the primordial hairy character of their early ape-like progenitors.), and possibly with the Ainos, who inhabit the northern islands of the Japan archipelago. But the laws of inheritance are so complex that we can seldom understand their action. If the greater hairiness of certain races be the result of reversion, unchecked by any form of selection, its extreme variability, even within the limits of the same race, ceases to be remarkable. (24. Hardly any view advanced in this work has met with so much disfavour (see for instance, Sprengel, 'Die Fortschritte des Darwinismus,' 1874, p. 80) as the above explanation of the loss of hair in mankind through sexual selection; but none of the opposed arguments seem to me of much weight, in comparison with the facts shewing that the nudity of the skin is to a certain extent a secondary sexual character in man and in some of the Quadrumana.) With respect to the beard in man, if we turn to our best guide, the Quadrumana, we find beards equally developed in both sexes of many species, but in some, either confined to the males, or more developed in them than in the females. From this fact and from the curious arrangement, as well as the bright colours of the hair about the heads of many monkeys, it is highly probable, as before explained, that the males first acquired their beards through sexual selection as an ornament, transmitting them in most cases, equally or nearly so, to their offspring of both sexes. We know from Eschricht (25. 'Ueber die Richtung der Haare am Menschlichen Körper,' in Müller's 'Archiv. für Anat. und Phys.' 1837, s. 40.) that with mankind the female as well as the male foetus is furnished with much hair on the face, especially round the mouth; and this indicates that we are descended from progenitors of whom both sexes were bearded. It appears therefore at first sight probable that man has retained his beard from a very early period, whilst woman lost her beard at the same time that her body became almost completely divested of hair. Even the colour of our beards seems to have been inherited from an ape-like progenitor; for when there is any difference in tint between the hair of the head and the beard, the latter is lighter coloured in all monkeys and in man. In those Quadrumana in which the male has a larger beard than that of the female, it is fully developed only at maturity, just as with mankind; and it is possible that only the later stages of development have been retained by man. In opposition to this view of the retention of the beard from an early period is the fact of its great variability in different races, and even within the same race; for this indicates reversion,--long lost characters being very apt to vary on re-appearance. Nor must we overlook the part which sexual selection may have played in later times; for we know that with savages the men of the beardless races take infinite pains in eradicating every hair from their faces as something odious, whilst the men of the bearded races feel the greatest pride in their beards. The women, no doubt, participate in these feelings, and if so sexual selection can hardly have failed to have effected something in the course of later times. It is also possible that the long-continued habit of eradicating the hair may have produced an inherited effect. Dr. Brown-Sequard has shewn that if certain animals are operated on in a particular manner, their offspring are affected. Further evidence could be given of the inheritance of the effects of mutilations; but a fact lately ascertained by Mr. Salvin (26. On the tail-feathers of Motmots, 'Proceedings of the Zoological Society,' 1873, p. 429.) has a more direct bearing on the present question; for he has shewn that the motmots, which are known habitually to bite off the barbs of the two central tail-feathers, have the barbs of these feathers naturally somewhat reduced. (27. Mr. Sproat has suggested ('Scenes and Studies of Savage Life,' 1868, p. 25) this same view. Some distinguished ethnologists, amongst others M. Gosse of Geneva, believe that artificial modifications of the skull tend to be inherited.) Nevertheless, with mankind the habit of eradicating the beard and the hairs on the body would probably not have arisen until these had already become by some means reduced. It is difficult to form any judgment as to how the hair on the head became developed to its present great length in many races. Eschricht (28. 'Ueber die Richtung,' ibid. s. 40.) states that in the human foetus the hair on the face during the fifth month is longer than that on the head; and this indicates that our semi-human progenitors were not furnished with long tresses, which must therefore have been a late acquisition. This is likewise indicated by the extraordinary difference in the length of the hair in the different races; in the negro the hair forms a mere curly mat; with us it is of great length, and with the American natives it not rarely reaches to the ground. Some species of Semnopithecus have their heads covered with moderately long hair, and this probably serves as an ornament and was acquired through sexual selection. The same view may perhaps be extended to mankind, for we know that long tresses are now and were formerly much admired, as may be observed in the works of almost every poet; St. Paul says, "if a woman have long hair, it is a glory to her;" and we have seen that in North America a chief was elected solely from the length of his hair. COLOUR OF THE SKIN. The best kind of evidence that in man the colour of the skin has been modified through sexual selection is scanty; for in most races the sexes do not differ in this respect, and only slightly, as we have seen, in others. We know, however, from the many facts already given that the colour of the skin is regarded by the men of all races as a highly important element in their beauty; so that it is a character which would be likely to have been modified through selection, as has occurred in innumerable instances with the lower animals. It seems at first sight a monstrous supposition that the jet-blackness of the negro should have been gained through sexual selection; but this view is supported by various analogies, and we know that negroes admire their own colour. With mammals, when the sexes differ in colour, the male is often black or much darker than the female; and it depends merely on the form of inheritance whether this or any other tint is transmitted to both sexes or to one alone. The resemblance to a negro in miniature of Pithecia satanas with his jet black skin, white rolling eyeballs, and hair parted on the top of the head, is almost ludicrous. The colour of the face differs much more widely in the various kinds of monkeys than it does in the races of man; and we have some reason to believe that the red, blue, orange, almost white and black tints of their skin, even when common to both sexes, as well as the bright colours of their fur, and the ornamental tufts about the head, have all been acquired through sexual selection. As the order of development during growth, generally indicates the order in which the characters of a species have been developed and modified during previous generations; and as the newly-born infants of the various races of man do not differ nearly as much in colour as do the adults, although their bodies are as completely destitute of hair, we have some slight evidence that the tints of the different races were acquired at a period subsequent to the removal of the hair, which must have occurred at a very early period in the history of man. SUMMARY. We may conclude that the greater size, strength, courage, pugnacity, and energy of man, in comparison with woman, were acquired during primeval times, and have subsequently been augmented, chiefly through the contests of rival males for the possession of the females. The greater intellectual vigour and power of invention in man is probably due to natural selection, combined with the inherited effects of habit, for the most able men will have succeeded best in defending and providing for themselves and for their wives and offspring. As far as the extreme intricacy of the subject permits us to judge, it appears that our male ape-like progenitors acquired their beards as an ornament to charm or excite the opposite sex, and transmitted them only to their male offspring. The females apparently first had their bodies denuded of hair, also as a sexual ornament; but they transmitted this character almost equally to both sexes. It is not improbable that the females were modified in other respects for the same purpose and by the same means; so that women have acquired sweeter voices and become more beautiful than men. It deserves attention that with mankind the conditions were in many respects much more favourable for sexual selection, during a very early period, when man had only just attained to the rank of manhood, than during later times. For he would then, as we may safely conclude, have been guided more by his instinctive passions, and less by foresight or reason. He would have jealously guarded his wife or wives. He would not have practised infanticide; nor valued his wives merely as useful slaves; nor have been betrothed to them during infancy. Hence we may infer that the races of men were differentiated, as far as sexual selection is concerned, in chief part at a very remote epoch; and this conclusion throws light on the remarkable fact that at the most ancient period, of which we have not as yet any record, the races of man had already come to differ nearly or quite as much as they do at the present day. The views here advanced, on the part which sexual selection has played in the history of man, want scientific precision. He who does not admit this agency in the case of the lower animals, will disregard all that I have written in the later chapters on man. We cannot positively say that this character, but not that, has been thus modified; it has, however, been shewn that the races of man differ from each other and from their nearest allies, in certain characters which are of no service to them in their daily habits of life, and which it is extremely probable would have been modified through sexual selection. We have seen that with the lowest savages the people of each tribe admire their own characteristic qualities,--the shape of the head and face, the squareness of the cheek-bones, the prominence or depression of the nose, the colour of the skin, the length of the hair on the head, the absence of hair on the face and body, or the presence of a great beard, and so forth. Hence these and other such points could hardly fail to be slowly and gradually exaggerated, from the more powerful and able men in each tribe, who would succeed in rearing the largest number of offspring, having selected during many generations for their wives the most strongly characterised and therefore most attractive women. For my own part I conclude that of all the causes which have led to the differences in external appearance between the races of man, and to a certain extent between man and the lower animals, sexual selection has been the most efficient. CHAPTER XXI. GENERAL SUMMARY AND CONCLUSION. Main conclusion that man is descended from some lower form--Manner of development--Genealogy of man--Intellectual and moral faculties--Sexual Selection--Concluding remarks. A brief summary will be sufficient to recall to the reader's mind the more salient points in this work. Many of the views which have been advanced are highly speculative, and some no doubt will prove erroneous; but I have in every case given the reasons which have led me to one view rather than to another. It seemed worth while to try how far the principle of evolution would throw light on some of the more complex problems in the natural history of man. False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for every one takes a salutary pleasure in proving their falseness: and when this is done, one path towards error is closed and the road to truth is often at the same time opened. The main conclusion here arrived at, and now held by many naturalists who are well competent to form a sound judgment, is that man is descended from some less highly organised form. The grounds upon which this conclusion rests will never be shaken, for the close similarity between man and the lower animals in embryonic development, as well as in innumerable points of structure and constitution, both of high and of the most trifling importance,--the rudiments which he retains, and the abnormal reversions to which he is occasionally liable,--are facts which cannot be disputed. They have long been known, but until recently they told us nothing with respect to the origin of man. Now when viewed by the light of our knowledge of the whole organic world, their meaning is unmistakable. The great principle of evolution stands up clear and firm, when these groups or facts are considered in connection with others, such as the mutual affinities of the members of the same group, their geographical distribution in past and present times, and their geological succession. It is incredible that all these facts should speak falsely. He who is not content to look, like a savage, at the phenomena of nature as disconnected, cannot any longer believe that man is the work of a separate act of creation. He will be forced to admit that the close resemblance of the embryo of man to that, for instance, of a dog--the construction of his skull, limbs and whole frame on the same plan with that of other mammals, independently of the uses to which the parts may be put--the occasional re-appearance of various structures, for instance of several muscles, which man does not normally possess, but which are common to the Quadrumana--and a crowd of analogous facts--all point in the plainest manner to the conclusion that man is the co-descendant with other mammals of a common progenitor. We have seen that man incessantly presents individual differences in all parts of his body and in his mental faculties. These differences or variations seem to be induced by the same general causes, and to obey the same laws as with the lower animals. In both cases similar laws of inheritance prevail. Man tends to increase at a greater rate than his means of subsistence; consequently he is occasionally subjected to a severe struggle for existence, and natural selection will have effected whatever lies within its scope. A succession of strongly-marked variations of a similar nature is by no means requisite; slight fluctuating differences in the individual suffice for the work of natural selection; not that we have any reason to suppose that in the same species, all parts of the organisation tend to vary to the same degree. We may feel assured that the inherited effects of the long-continued use or disuse of parts will have done much in the same direction with natural selection. Modifications formerly of importance, though no longer of any special use, are long-inherited. When one part is modified, other parts change through the principle of correlation, of which we have instances in many curious cases of correlated monstrosities. Something may be attributed to the direct and definite action of the surrounding conditions of life, such as abundant food, heat or moisture; and lastly, many characters of slight physiological importance, some indeed of considerable importance, have been gained through sexual selection. No doubt man, as well as every other animal, presents structures, which seem to our limited knowledge, not to be now of any service to him, nor to have been so formerly, either for the general conditions of life, or in the relations of one sex to the other. Such structures cannot be accounted for by any form of selection, or by the inherited effects of the use and disuse of parts. We know, however, that many strange and strongly-marked peculiarities of structure occasionally appear in our domesticated productions, and if their unknown causes were to act more uniformly, they would probably become common to all the individuals of the species. We may hope hereafter to understand something about the causes of such occasional modifications, especially through the study of monstrosities: hence the labours of experimentalists, such as those of M. Camille Dareste, are full of promise for the future. In general we can only say that the cause of each slight variation and of each monstrosity lies much more in the constitution of the organism, than in the nature of the surrounding conditions; though new and changed conditions certainly play an important part in exciting organic changes of many kinds. Through the means just specified, aided perhaps by others as yet undiscovered, man has been raised to his present state. But since he attained to the rank of manhood, he has diverged into distinct races, or as they may be more fitly called, sub-species. Some of these, such as the Negro and European, are so distinct that, if specimens had been brought to a naturalist without any further information, they would undoubtedly have been considered by him as good and true species. Nevertheless all the races agree in so many unimportant details of structure and in so many mental peculiarities that these can be accounted for only by inheritance from a common progenitor; and a progenitor thus characterised would probably deserve to rank as man. It must not be supposed that the divergence of each race from the other races, and of all from a common stock, can be traced back to any one pair of progenitors. On the contrary, at every stage in the process of modification, all the individuals which were in any way better fitted for their conditions of life, though in different degrees, would have survived in greater numbers than the less well-fitted. The process would have been like that followed by man, when he does not intentionally select particular individuals, but breeds from all the superior individuals, and neglects the inferior. He thus slowly but surely modifies his stock, and unconsciously forms a new strain. So with respect to modifications acquired independently of selection, and due to variations arising from the nature of the organism and the action of the surrounding conditions, or from changed habits of life, no single pair will have been modified much more than the other pairs inhabiting the same country, for all will have been continually blended through free intercrossing. By considering the embryological structure of man,--the homologies which he presents with the lower animals,--the rudiments which he retains,--and the reversions to which he is liable, we can partly recall in imagination the former condition of our early progenitors; and can approximately place them in their proper place in the zoological series. We thus learn that man is descended from a hairy, tailed quadruped, probably arboreal in its habits, and an inhabitant of the Old World. This creature, if its whole structure had been examined by a naturalist, would have been classed amongst the Quadrumana, as surely as the still more ancient progenitor of the Old and New World monkeys. The Quadrumana and all the higher mammals are probably derived from an ancient marsupial animal, and this through a long line of diversified forms, from some amphibian-like creature, and this again from some fish-like animal. In the dim obscurity of the past we can see that the early progenitor of all the Vertebrata must have been an aquatic animal, provided with branchiae, with the two sexes united in the same individual, and with the most important organs of the body (such as the brain and heart) imperfectly or not at all developed. This animal seems to have been more like the larvae of the existing marine Ascidians than any other known form. The high standard of our intellectual powers and moral disposition is the greatest difficulty which presents itself, after we have been driven to this conclusion on the origin of man. But every one who admits the principle of evolution, must see that the mental powers of the higher animals, which are the same in kind with those of man, though so different in degree, are capable of advancement. Thus the interval between the mental powers of one of the higher apes and of a fish, or between those of an ant and scale-insect, is immense; yet their development does not offer any special difficulty; for with our domesticated animals, the mental faculties are certainly variable, and the variations are inherited. No one doubts that they are of the utmost importance to animals in a state of nature. Therefore the conditions are favourable for their development through natural selection. The same conclusion may be extended to man; the intellect must have been all-important to him, even at a very remote period, as enabling him to invent and use language, to make weapons, tools, traps, etc., whereby with the aid of his social habits, he long ago became the most dominant of all living creatures. A great stride in the development of the intellect will have followed, as soon as the half-art and half-instinct of language came into use; for the continued use of language will have reacted on the brain and produced an inherited effect; and this again will have reacted on the improvement of language. As Mr. Chauncey Wright (1. 'On the Limits of Natural Selection,' in the 'North American Review,' Oct. 1870, p. 295.) has well remarked, the largeness of the brain in man relatively to his body, compared with the lower animals, may be attributed in chief part to the early use of some simple form of language,--that wonderful engine which affixes signs to all sorts of objects and qualities, and excites trains of thought which would never arise from the mere impression of the senses, or if they did arise could not be followed out. The higher intellectual powers of man, such as those of ratiocination, abstraction, self-consciousness, etc., probably follow from the continued improvement and exercise of the other mental faculties. The development of the moral qualities is a more interesting problem. The foundation lies in the social instincts, including under this term the family ties. These instincts are highly complex, and in the case of the lower animals give special tendencies towards certain definite actions; but the more important elements are love, and the distinct emotion of sympathy. Animals endowed with the social instincts take pleasure in one another's company, warn one another of danger, defend and aid one another in many ways. These instincts do not extend to all the individuals of the species, but only to those of the same community. As they are highly beneficial to the species, they have in all probability been acquired through natural selection. A moral being is one who is capable of reflecting on his past actions and their motives--of approving of some and disapproving of others; and the fact that man is the one being who certainly deserves this designation, is the greatest of all distinctions between him and the lower animals. But in the fourth chapter I have endeavoured to shew that the moral sense follows, firstly, from the enduring and ever-present nature of the social instincts; secondly, from man's appreciation of the approbation and disapprobation of his fellows; and thirdly, from the high activity of his mental faculties, with past impressions extremely vivid; and in these latter respects he differs from the lower animals. Owing to this condition of mind, man cannot avoid looking both backwards and forwards, and comparing past impressions. Hence after some temporary desire or passion has mastered his social instincts, he reflects and compares the now weakened impression of such past impulses with the ever-present social instincts; and he then feels that sense of dissatisfaction which all unsatisfied instincts leave behind them, he therefore resolves to act differently for the future,--and this is conscience. Any instinct, permanently stronger or more enduring than another, gives rise to a feeling which we express by saying that it ought to be obeyed. A pointer dog, if able to reflect on his past conduct, would say to himself, I ought (as indeed we say of him) to have pointed at that hare and not have yielded to the passing temptation of hunting it. Social animals are impelled partly by a wish to aid the members of their community in a general manner, but more commonly to perform certain definite actions. Man is impelled by the same general wish to aid his fellows; but has few or no special instincts. He differs also from the lower animals in the power of expressing his desires by words, which thus become a guide to the aid required and bestowed. The motive to give aid is likewise much modified in man: it no longer consists solely of a blind instinctive impulse, but is much influenced by the praise or blame of his fellows. The appreciation and the bestowal of praise and blame both rest on sympathy; and this emotion, as we have seen, is one of the most important elements of the social instincts. Sympathy, though gained as an instinct, is also much strengthened by exercise or habit. As all men desire their own happiness, praise or blame is bestowed on actions and motives, according as they lead to this end; and as happiness is an essential part of the general good, the greatest-happiness principle indirectly serves as a nearly safe standard of right and wrong. As the reasoning powers advance and experience is gained, the remoter effects of certain lines of conduct on the character of the individual, and on the general good, are perceived; and then the self-regarding virtues come within the scope of public opinion, and receive praise, and their opposites blame. But with the less civilised nations reason often errs, and many bad customs and base superstitions come within the same scope, and are then esteemed as high virtues, and their breach as heavy crimes. The moral faculties are generally and justly esteemed as of higher value than the intellectual powers. But we should bear in mind that the activity of the mind in vividly recalling past impressions is one of the fundamental though secondary bases of conscience. This affords the strongest argument for educating and stimulating in all possible ways the intellectual faculties of every human being. No doubt a man with a torpid mind, if his social affections and sympathies are well developed, will be led to good actions, and may have a fairly sensitive conscience. But whatever renders the imagination more vivid and strengthens the habit of recalling and comparing past impressions, will make the conscience more sensitive, and may even somewhat compensate for weak social affections and sympathies. The moral nature of man has reached its present standard, partly through the advancement of his reasoning powers and consequently of a just public opinion, but especially from his sympathies having been rendered more tender and widely diffused through the effects of habit, example, instruction, and reflection. It is not improbable that after long practice virtuous tendencies may be inherited. With the more civilised races, the conviction of the existence of an all-seeing Deity has had a potent influence on the advance of morality. Ultimately man does not accept the praise or blame of his fellows as his sole guide, though few escape this influence, but his habitual convictions, controlled by reason, afford him the safest rule. His conscience then becomes the supreme judge and monitor. Nevertheless the first foundation or origin of the moral sense lies in the social instincts, including sympathy; and these instincts no doubt were primarily gained, as in the case of the lower animals, through natural selection. The belief in God has often been advanced as not only the greatest, but the most complete of all the distinctions between man and the lower animals. It is however impossible, as we have seen, to maintain that this belief is innate or instinctive in man. On the other hand a belief in all-pervading spiritual agencies seems to be universal; and apparently follows from a considerable advance in man's reason, and from a still greater advance in his faculties of imagination, curiosity and wonder. I am aware that the assumed instinctive belief in God has been used by many persons as an argument for His existence. But this is a rash argument, as we should thus be compelled to believe in the existence of many cruel and malignant spirits, only a little more powerful than man; for the belief in them is far more general than in a beneficent Deity. The idea of a universal and beneficent Creator does not seem to arise in the mind of man, until he has been elevated by long-continued culture. He who believes in the advancement of man from some low organised form, will naturally ask how does this bear on the belief in the immortality of the soul. The barbarous races of man, as Sir J. Lubbock has shewn, possess no clear belief of this kind; but arguments derived from the primeval beliefs of savages are, as we have just seen, of little or no avail. Few persons feel any anxiety from the impossibility of determining at what precise period in the development of the individual, from the first trace of a minute germinal vesicle, man becomes an immortal being; and there is no greater cause for anxiety because the period cannot possibly be determined in the gradually ascending organic scale. (2. The Rev. J.A. Picton gives a discussion to this effect in his 'New Theories and the Old Faith,' 1870.) I am aware that the conclusions arrived at in this work will be denounced by some as highly irreligious; but he who denounces them is bound to shew why it is more irreligious to explain the origin of man as a distinct species by descent from some lower form, through the laws of variation and natural selection, than to explain the birth of the individual through the laws of ordinary reproduction. The birth both of the species and of the individual are equally parts of that grand sequence of events, which our minds refuse to accept as the result of blind chance. The understanding revolts at such a conclusion, whether or not we are able to believe that every slight variation of structure,--the union of each pair in marriage, the dissemination of each seed,--and other such events, have all been ordained for some special purpose. Sexual selection has been treated at great length in this work; for, as I have attempted to shew, it has played an important part in the history of the organic world. I am aware that much remains doubtful, but I have endeavoured to give a fair view of the whole case. In the lower divisions of the animal kingdom, sexual selection seems to have done nothing: such animals are often affixed for life to the same spot, or have the sexes combined in the same individual, or what is still more important, their perceptive and intellectual faculties are not sufficiently advanced to allow of the feelings of love and jealousy, or of the exertion of choice. When, however, we come to the Arthropoda and Vertebrata, even to the lowest classes in these two great Sub-Kingdoms, sexual selection has effected much. In the several great classes of the animal kingdom,--in mammals, birds, reptiles, fishes, insects, and even crustaceans,--the differences between the sexes follow nearly the same rules. The males are almost always the wooers; and they alone are armed with special weapons for fighting with their rivals. They are generally stronger and larger than the females, and are endowed with the requisite qualities of courage and pugnacity. They are provided, either exclusively or in a much higher degree than the females, with organs for vocal or instrumental music, and with odoriferous glands. They are ornamented with infinitely diversified appendages, and with the most brilliant or conspicuous colours, often arranged in elegant patterns, whilst the females are unadorned. When the sexes differ in more important structures, it is the male which is provided with special sense-organs for discovering the female, with locomotive organs for reaching her, and often with prehensile organs for holding her. These various structures for charming or securing the female are often developed in the male during only part of the year, namely the breeding-season. They have in many cases been more or less transferred to the females; and in the latter case they often appear in her as mere rudiments. They are lost or never gained by the males after emasculation. Generally they are not developed in the male during early youth, but appear a short time before the age for reproduction. Hence in most cases the young of both sexes resemble each other; and the female somewhat resembles her young offspring throughout life. In almost every great class a few anomalous cases occur, where there has been an almost complete transposition of the characters proper to the two sexes; the females assuming characters which properly belong to the males. This surprising uniformity in the laws regulating the differences between the sexes in so many and such widely separated classes, is intelligible if we admit the action of one common cause, namely sexual selection. Sexual selection depends on the success of certain individuals over others of the same sex, in relation to the propagation of the species; whilst natural selection depends on the success of both sexes, at all ages, in relation to the general conditions of life. The sexual struggle is of two kinds; in the one it is between individuals of the same sex, generally the males, in order to drive away or kill their rivals, the females remaining passive; whilst in the other, the struggle is likewise between the individuals of the same sex, in order to excite or charm those of the opposite sex, generally the females, which no longer remain passive, but select the more agreeable partners. This latter kind of selection is closely analogous to that which man unintentionally, yet effectually, brings to bear on his domesticated productions, when he preserves during a long period the most pleasing or useful individuals, without any wish to modify the breed. The laws of inheritance determine whether characters gained through sexual selection by either sex shall be transmitted to the same sex, or to both; as well as the age at which they shall be developed. It appears that variations arising late in life are commonly transmitted to one and the same sex. Variability is the necessary basis for the action of selection, and is wholly independent of it. It follows from this, that variations of the same general nature have often been taken advantage of and accumulated through sexual selection in relation to the propagation of the species, as well as through natural selection in relation to the general purposes of life. Hence secondary sexual characters, when equally transmitted to both sexes can be distinguished from ordinary specific characters only by the light of analogy. The modifications acquired through sexual selection are often so strongly pronounced that the two sexes have frequently been ranked as distinct species, or even as distinct genera. Such strongly-marked differences must be in some manner highly important; and we know that they have been acquired in some instances at the cost not only of inconvenience, but of exposure to actual danger. The belief in the power of sexual selection rests chiefly on the following considerations. Certain characters are confined to one sex; and this alone renders it probable that in most cases they are connected with the act of reproduction. In innumerable instances these characters are fully developed only at maturity, and often during only a part of the year, which is always the breeding-season. The males (passing over a few exceptional cases) are the more active in courtship; they are the better armed, and are rendered the more attractive in various ways. It is to be especially observed that the males display their attractions with elaborate care in the presence of the females; and that they rarely or never display them excepting during the season of love. It is incredible that all this should be purposeless. Lastly we have distinct evidence with some quadrupeds and birds, that the individuals of one sex are capable of feeling a strong antipathy or preference for certain individuals of the other sex. Bearing in mind these facts, and the marked results of man's unconscious selection, when applied to domesticated animals and cultivated plants, it seems to me almost certain that if the individuals of one sex were during a long series of generations to prefer pairing with certain individuals of the other sex, characterised in some peculiar manner, the offspring would slowly but surely become modified in this same manner. I have not attempted to conceal that, excepting when the males are more numerous than the females, or when polygamy prevails, it is doubtful how the more attractive males succeed in leaving a large number of offspring to inherit their superiority in ornaments or other charms than the less attractive males; but I have shewn that this would probably follow from the females,--especially the more vigorous ones, which would be the first to breed,--preferring not only the more attractive but at the same time the more vigorous and victorious males. Although we have some positive evidence that birds appreciate bright and beautiful objects, as with the bower-birds of Australia, and although they certainly appreciate the power of song, yet I fully admit that it is astonishing that the females of many birds and some mammals should be endowed with sufficient taste to appreciate ornaments, which we have reason to attribute to sexual selection; and this is even more astonishing in the case of reptiles, fish, and insects. But we really know little about the minds of the lower animals. It cannot be supposed, for instance, that male birds of paradise or peacocks should take such pains in erecting, spreading, and vibrating their beautiful plumes before the females for no purpose. We should remember the fact given on excellent authority in a former chapter, that several peahens, when debarred from an admired male, remained widows during a whole season rather than pair with another bird. Nevertheless I know of no fact in natural history more wonderful than that the female Argus pheasant should appreciate the exquisite shading of the ball-and-socket ornaments and the elegant patterns on the wing-feather of the male. He who thinks that the male was created as he now exists must admit that the great plumes, which prevent the wings from being used for flight, and which are displayed during courtship and at no other time in a manner quite peculiar to this one species, were given to him as an ornament. If so, he must likewise admit that the female was created and endowed with the capacity of appreciating such ornaments. I differ only in the conviction that the male Argus pheasant acquired his beauty gradually, through the preference of the females during many generations for the more highly ornamented males; the aesthetic capacity of the females having been advanced through exercise or habit, just as our own taste is gradually improved. In the male through the fortunate chance of a few feathers being left unchanged, we can distinctly trace how simple spots with a little fulvous shading on one side may have been developed by small steps into the wonderful ball-and-socket ornaments; and it is probable that they were actually thus developed. Everyone who admits the principle of evolution, and yet feels great difficulty in admitting that female mammals, birds, reptiles, and fish, could have acquired the high taste implied by the beauty of the males, and which generally coincides with our own standard, should reflect that the nerve-cells of the brain in the highest as well as in the lowest members of the Vertebrate series, are derived from those of the common progenitor of this great Kingdom. For we can thus see how it has come to pass that certain mental faculties, in various and widely distinct groups of animals, have been developed in nearly the same manner and to nearly the same degree. The reader who has taken the trouble to go through the several chapters devoted to sexual selection, will be able to judge how far the conclusions at which I have arrived are supported by sufficient evidence. If he accepts these conclusions he may, I think, safely extend them to mankind; but it would be superfluous here to repeat what I have so lately said on the manner in which sexual selection apparently has acted on man, both on the male and female side, causing the two sexes to differ in body and mind, and the several races to differ from each other in various characters, as well as from their ancient and lowly-organised progenitors. He who admits the principle of sexual selection will be led to the remarkable conclusion that the nervous system not only regulates most of the existing functions of the body, but has indirectly influenced the progressive development of various bodily structures and of certain mental qualities. Courage, pugnacity, perseverance, strength and size of body, weapons of all kinds, musical organs, both vocal and instrumental, bright colours and ornamental appendages, have all been indirectly gained by the one sex or the other, through the exertion of choice, the influence of love and jealousy, and the appreciation of the beautiful in sound, colour or form; and these powers of the mind manifestly depend on the development of the brain. Man scans with scrupulous care the character and pedigree of his horses, cattle, and dogs before he matches them; but when he comes to his own marriage he rarely, or never, takes any such care. He is impelled by nearly the same motives as the lower animals, when they are left to their own free choice, though he is in so far superior to them that he highly values mental charms and virtues. On the other hand he is strongly attracted by mere wealth or rank. Yet he might by selection do something not only for the bodily constitution and frame of his offspring, but for their intellectual and moral qualities. Both sexes ought to refrain from marriage if they are in any marked degree inferior in body or mind; but such hopes are Utopian and will never be even partially realised until the laws of inheritance are thoroughly known. Everyone does good service, who aids towards this end. When the principles of breeding and inheritance are better understood, we shall not hear ignorant members of our legislature rejecting with scorn a plan for ascertaining whether or not consanguineous marriages are injurious to man. The advancement of the welfare of mankind is a most intricate problem: all ought to refrain from marriage who cannot avoid abject poverty for their children; for poverty is not only a great evil, but tends to its own increase by leading to recklessness in marriage. On the other hand, as Mr. Galton has remarked, if the prudent avoid marriage, whilst the reckless marry, the inferior members tend to supplant the better members of society. Man, like every other animal, has no doubt advanced to his present high condition through a struggle for existence consequent on his rapid multiplication; and if he is to advance still higher, it is to be feared that he must remain subject to a severe struggle. Otherwise he would sink into indolence, and the more gifted men would not be more successful in the battle of life than the less gifted. Hence our natural rate of increase, though leading to many and obvious evils, must not be greatly diminished by any means. There should be open competition for all men; and the most able should not be prevented by laws or customs from succeeding best and rearing the largest number of offspring. Important as the struggle for existence has been and even still is, yet as far as the highest part of man's nature is concerned there are other agencies more important. For the moral qualities are advanced, either directly or indirectly, much more through the effects of habit, the reasoning powers, instruction, religion, etc., than through natural selection; though to this latter agency may be safely attributed the social instincts, which afforded the basis for the development of the moral sense. The main conclusion arrived at in this work, namely, that man is descended from some lowly organised form, will, I regret to think, be highly distasteful to many. But there can hardly be a doubt that we are descended from barbarians. The astonishment which I felt on first seeing a party of Fuegians on a wild and broken shore will never be forgotten by me, for the reflection at once rushed into my mind--such were our ancestors. These men were absolutely naked and bedaubed with paint, their long hair was tangled, their mouths frothed with excitement, and their expression was wild, startled, and distrustful. They possessed hardly any arts, and like wild animals lived on what they could catch; they had no government, and were merciless to every one not of their own small tribe. He who has seen a savage in his native land will not feel much shame, if forced to acknowledge that the blood of some more humble creature flows in his veins. For my own part I would as soon be descended from that heroic little monkey, who braved his dreaded enemy in order to save the life of his keeper, or from that old baboon, who descending from the mountains, carried away in triumph his young comrade from a crowd of astonished dogs--as from a savage who delights to torture his enemies, offers up bloody sacrifices, practices infanticide without remorse, treats his wives like slaves, knows no decency, and is haunted by the grossest superstitions. Man may be excused for feeling some pride at having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen, instead of having been aboriginally placed there, may give him hope for a still higher destiny in the distant future. But we are not here concerned with hopes or fears, only with the truth as far as our reason permits us to discover it; and I have given the evidence to the best of my ability. We must, however, acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system--with all these exalted powers--Man still bears in his bodily frame the indelible stamp of his lowly origin. SUPPLEMENTAL NOTE. ON SEXUAL SELECTION IN RELATION TO MONKEYS. Reprinted from NATURE, November 2, 1876, p. 18. In the discussion on Sexual Selection in my 'Descent of Man,' no case interested and perplexed me so much as the brightly-coloured hinder ends and adjoining parts of certain monkeys. As these parts are more brightly coloured in one sex than the other, and as they become more brilliant during the season of love, I concluded that the colours had been gained as a sexual attraction. I was well aware that I thus laid myself open to ridicule; though in fact it is not more surprising that a monkey should display his bright-red hinder end than that a peacock should display his magnificent tail. I had, however, at that time no evidence of monkeys exhibiting this part of their bodies during their courtship; and such display in the case of birds affords the best evidence that the ornaments of the males are of service to them by attracting or exciting the females. I have lately read an article by Joh. von Fischer, of Gotha, published in 'Der Zoologische Garten,' April 1876, on the expression of monkeys under various emotions, which is well worthy of study by any one interested in the subject, and which shews that the author is a careful and acute observer. In this article there is an account of the behaviour of a young male mandrill when he first beheld himself in a looking-glass, and it is added, that after a time he turned round and presented his red hinder end to the glass. Accordingly I wrote to Herr J. von Fischer to ask what he supposed was the meaning of this strange action, and he has sent me two long letters full of new and curious details, which will, I hope, be hereafter published. He says that he was himself at first perplexed by the above action, and was thus led carefully to observe several individuals of various other species of monkeys, which he has long kept in his house. He finds that not only the mandrill (Cynocephalus mormon) but the drill (C. leucophaeus) and three other kinds of baboons (C. hamadryas, sphinx, and babouin), also Cynopithecus niger, and Macacus rhesus and nemestrinus, turn this part of their bodies, which in all these species is more or less brightly coloured, to him when they are pleased, and to other persons as a sort of greeting. He took pains to cure a Macacus rhesus, which he had kept for five years, of this indecorous habit, and at last succeeded. These monkeys are particularly apt to act in this manner, grinning at the same time, when first introduced to a new monkey, but often also to their old monkey friends; and after this mutual display they begin to play together. The young mandrill ceased spontaneously after a time to act in this manner towards his master, von Fischer, but continued to do so towards persons who were strangers and to new monkeys. A young Cynopithecus niger never acted, excepting on one occasion, in this way towards his master, but frequently towards strangers, and continues to do so up to the present time. From these facts Von Fischer concludes that the monkeys which behaved in this manner before a looking-glass (viz., the mandrill, drill, Cynopithecus niger, Macacus rhesus and nemestrinus) acted as if their reflection were a new acquaintance. The mandrill and drill, which have their hinder ends especially ornamented, display it even whilst quite young, more frequently and more ostentatiously than do the other kinds. Next in order comes Cynocephalus hamadryas, whilst the other species act in this manner seldomer. The individuals, however, of the same species vary in this respect, and some which were very shy never displayed their hinder ends. It deserves especial attention that Von Fischer has never seen any species purposely exhibit the hinder part of its body, if not at all coloured. This remark applies to many individuals of Macacus cynomolgus and Cercocebus radiatus (which is closely allied to M. rhesus), to three species of Cercopithecus and several American monkeys. The habit of turning the hinder ends as a greeting to an old friend or new acquaintance, which seems to us so odd, is not really more so than the habits of many savages, for instance that of rubbing their bellies with their hands, or rubbing noses together. The habit with the mandrill and drill seems to be instinctive or inherited, as it was followed by very young animals; but it is modified or guided, like so many other instincts, by observation, for Von Fischer says that they take pains to make their display fully; and if made before two observers, they turn to him who seems to pay the most attention. With respect to the origin of the habit, Von Fischer remarks that his monkeys like to have their naked hinder ends patted or stroked, and that they then grunt with pleasure. They often also turn this part of their bodies to other monkeys to have bits of dirt picked off, and so no doubt it would be with respect to thorns. But the habit with adult animals is connected to a certain extent with sexual feelings, for Von Fischer watched through a glass door a female Cynopithecus niger, and she during several days, "umdrehte und dem Männchen mit gurgelnden Tönen die stark geröthete Sitzflache zeigte, was ich früher nie an diesem Thier bemerkt hatte. Beim Anblick dieses Gegenstandes erregte sich das Männchen sichtlich, denn es polterte heftig an den Stäben, ebenfalls gurgelnde Laute ausstossend." As all the monkeys which have the hinder parts of their bodies more or less brightly coloured live, according to Von Fischer, in open rocky places, he thinks that these colours serve to render one sex conspicuous at a distance to the other; but, as monkeys are such gregarious animals, I should have thought that there was no need for the sexes to recognise each other at a distance. It seems to me more probable that the bright colours, whether on the face or hinder end, or, as in the mandrill, on both, serve as a sexual ornament and attraction. Anyhow, as we now know that monkeys have the habit of turning their hinder ends towards other monkeys, it ceases to be at all surprising that it should have been this part of their bodies which has been more or less decorated. The fact that it is only the monkeys thus characterised which, as far as at present known, act in this manner as a greeting towards other monkeys renders it doubtful whether the habit was first acquired from some independent cause, and that afterwards the parts in question were coloured as a sexual ornament; or whether the colouring and the habit of turning round were first acquired through variation and sexual selection, and that afterwards the habit was retained as a sign of pleasure or as a greeting, through the principle of inherited association. This principle apparently comes into play on many occasions: thus it is generally admitted that the songs of birds serve mainly as an attraction during the season of love, and that the leks, or great congregations of the black-grouse, are connected with their courtship; but the habit of singing has been retained by some birds when they feel happy, for instance by the common robin, and the habit of congregating has been retained by the black-grouse during other seasons of the year. I beg leave to refer to one other point in relation to sexual selection. It has been objected that this form of selection, as far as the ornaments of the males are concerned, implies that all females within the same district must possess and exercise exactly the same taste. It should, however, be observed, in the first place, that although the range of variation of a species may be very large, it is by no means indefinite. I have elsewhere given a good instance of this fact in the pigeon, of which there are at least a hundred varieties differing widely in their colours, and at least a score of varieties of the fowl differing in the same kind of way; but the range of colour in these two species is extremely distinct. Therefore the females of natural species cannot have an unlimited scope for their taste. In the second place, I presume that no supporter of the principle of sexual selection believes that the females select particular points of beauty in the males; they are merely excited or attracted in a greater degree by one male than by another, and this seems often to depend, especially with birds, on brilliant colouring. Even man, excepting perhaps an artist, does not analyse the slight differences in the features of the woman whom he may admire, on which her beauty depends. The male mandrill has not only the hinder end of his body, but his face gorgeously coloured and marked with oblique ridges, a yellow beard, and other ornaments. We may infer from what we see of the variation of animals under domestication, that the above several ornaments of the mandrill were gradually acquired by one individual varying a little in one way, and another individual in another way. The males which were the handsomest or the most attractive in any manner to the females would pair oftenest, and would leave rather more offspring than other males. The offspring of the former, although variously intercrossed, would either inherit the peculiarities of their fathers or transmit an increased tendency to vary in the same manner. Consequently the whole body of males inhabiting the same country would tend from the effects of constant intercrossing to become modified almost uniformly, but sometimes a little more in one character and sometimes in another, though at an extremely slow rate; all ultimately being thus rendered more attractive to the females. The process is like that which I have called unconscious selection by man, and of which I have given several instances. In one country the inhabitants value a fleet or light dog or horse, and in another country a heavier and more powerful one; in neither country is there any selection of individual animals with lighter or stronger bodies and limbs; nevertheless after a considerable lapse of time the individuals are found to have been modified in the desired manner almost uniformly, though differently in each country. In two absolutely distinct countries inhabited by the same species, the individuals of which can never during long ages have intermigrated and intercrossed, and where, moreover, the variations will probably not have been identically the same, sexual selection might cause the males to differ. Nor does the belief appear to me altogether fanciful that two sets of females, surrounded by a very different environment, would be apt to acquire somewhat different tastes with respect to form, sound, or colour. However this may be, I have given in my 'Descent of Man' instances of closely-allied birds inhabiting distinct countries, of which the young and the females cannot be distinguished, whilst the adult males differ considerably, and this may be attributed with much probability to the action of sexual selection. INDEX. Abbot, C., on the battles of seals. Abductor of the fifth metatarsal, presence of, in man. Abercrombie, Dr., on disease of the brain affecting speech. Abipones, marriage customs of the. Abortion, prevalence of the practice of. Abou-Simbel, caves of. Abramis brama. Abstraction, power of, in animals. Acalles, stridulation of. Acanthodactylus capensis, sexual differences of colour in. Accentor Modularis. Acclimatisation, difference of, in different races of men. Achetidae, stridulation of the; rudimentary stridulating organs in female. Acilius sulcatus, elytra of the female. Acomus, development of spurs in the female of. Acridiidae, stridulation of the; rudimentary stridulating organs in female. Acromio-basilar muscle, and quadrupedal gait. Acting. Actiniae, bright colours of. Adams, Mr., migration of birds; intelligence of nut-hatch; on the Bombycilla carolinensis. Admiral butterfly. Adoption of the young of other animals by female monkeys. Advancement in the organic scale, Von Baer's definition of. Aeby, on the difference between the skulls of man and the quadrumana. Aesthetic faculty, not highly developed in savages. Affection, maternal; manifestation of, by animals; parental and filial, partly the result of natural selection; mutual, of birds; shewn by birds in confinement, for certain persons. Africa, probably the birthplace of man; South, crossed population of; South, retention of colour by the Dutch in; South, proportion of the sexes in the butterflies of; tattooing practised in; Northern, coiffure of natives of. Agassiz, L., on conscience in dogs; on the coincidence of the races of man with zoological provinces; on the number of species of man; on the courtship of the land-snails; on the brightness of the colours of male fishes during the breeding season; on the frontal protuberance of the males of Geophagus and Cichla; male fishes hatching ova in their mouths; sexual differences in colour of chromids; on the slight sexual differences of the South Americans; on the tattooing of the Amazonian Indians. Age, in relation to the transmission of characters in birds; variation in accordance with, in birds. Agelaeus phoeniceus. Ageronia feronia, noise produced by. Agrion, dimorphism in. Agrion Ramburii, sexes of. Agrionidae, difference in the sexes of. Agrotis exclamationis. Ague, tertian, dog suffering from. Ainos, hairiness of the. Aitchison, Mr., on sheep. Aithurus polytmus, young of. Albino birds. Alca torda, young of. Alces palmata. Alder and Hancock, MM., on the nudi-branch mollusca. Allen, J.A., vigour of birds earliest hatched; effect of difference of temperature, light, etc., on birds; colours of birds; on the relative size of the sexes of Callorhinus ursinus; on the name of Otaria jubata; on the pairing of seals; on sexual differences in the colour of bats. Allen, S., on the habits of Hoplopterus; on the plumes of herons; on the vernal moult of Herodius bubulcus. Alligator, courtship of the male; roaring of the male. Amadavat, pugnacity of male. Amadina Lathami, display of plumage by the male. Amadina castanotis, display of plumage by the male. Amazons, butterflies of the; fishes of the. America, variation in the skulls of aborigines of; wide range of aborigines of; lice of the natives of; general beardlessness of the natives of. America, North, butterflies of; Indians of, women a cause of strife among the; Indians of, their notions of female beauty. America, South, character of the natives of; population of parts of; piles of stones in; extinction of the fossil horse of; desert-birds of; slight sexual difference of the aborigines of; prevalence of infanticide in. American languages, often highly artificial. Americans, wide geographical range of; native, variability of; and negroes, difference of; aversion of, to hair on the face. Ammophila, on the jaws of. Ammotragus tragelaphus, hairy forelegs of. Amphibia, affinity of, to the ganoid fishes; vocal organs of the. Amphibians, breeding whilst immature. Amphioxus. Amphipoda, males sexually mature while young. Amunoph III., negro character of, features of. Anal appendages of insects. Analogous variation in the plumage of birds. Anas. Anas acuta, male plumage of. Anas boschas, male plumage of. Anas histrionica. Anas punctata. Anastomus oscitans, sexes and young of; white nuptial plumage of. Anatidae, voices of. Anax junius, differences in the sexes of. Andaman islanders, susceptible to change of climate. Anderson, Dr., on the tail of Macacus brunneus; the Bufo sikimmensis; sounds of Echis carinata. Andreana fulva. Anglo-Saxons, estimation of the beard among the. Animals, domesticated, more fertile than wild; cruelty of savages to; characters common to man and; domestic, change of breeds of. Annelida, colours of. Anobium tessellatum, sounds produced by. Anolis cristatellus, male, crest of; pugnacity of the male; throat-pouch of. Anser canadensis. Anset cygnoides; knob at the base of the beak of. Anser hyperboreus, whiteness of. Antelope, prong-horned, horns of. Antelopes, generally polygamous; horns of; canine teeth of some male; use of horns of; dorsal crests in; dewlaps of; winter change of two species of; peculiar markings of. Antennae, furnished with cushions in the male of Penthe. Anthidium manicatum, large male of. Anthocharis cardamines; sexual difference of colour in. Anthocharis genutia. Anthocharis sara. Anthophora acervorum, large male of. Anthophora retusa, difference of the sexes in. Anthropidae. Anthus, moulting of. Antics of birds. Antigua, Dr. Nicholson's observations on yellow fever in. Antilocapra americana, horns of. Antilope bezoartica, horned females of; sexual difference in the colour of. Antilope Dorcas and euchore. Antilope euchore, horns of. Antilope montana, rudimentary canines in the young male of. Antilope niger, sing-sing, caama, and gorgon, sexual differences in the colours of. Antilope oreas, horns of. Antilope saiga, polygamous habits of. Antilope strepsiceros, horns of. Antilope subgutturosa, absence of suborbital pits in. Antipathy, shewn by birds in confinement, to certain persons. Ants, large size of the cerebral ganglia in; soldier, large jaws of; playing together; memory in; intercommunication of, by means of the antennae; habits of; difference of the sexes in; recognition of each other by, after separation. Ants White, habits of. Anura. Apatania muliebris, male unknown. Apathus, difference of the sexes in. Apatura Iris. Apes, difference of the young, from the adult; semi-erect attitude of some; mastoid processes of; influences of the jaw-muscles on the physiognomy of; female, destitute of large canines; building platforms; imitative faculties of; anthropomorphous; probable speedy extermination of the; Gratiolet on the evolution of; canine teeth of male; females of some, less hairy beneath than the males. Apes, long-armed, their mode of progression. Aphasia, Dr. Bateman on. Apis mellifica, large male of. Apollo, Greek statues of. Apoplexy in Cebus Azarae. Appendages, anal, of insects. Approbation, influence of the love of. Aprosmictus scapulatus. Apus, proportion of sexes. Aquatic birds, frequency of white plumage in. Aquila chrysaetos. Arab women, elaborate and peculiar coiffure of. Arabs, fertility of crosses with other races; gashing of cheeks and temples among the. Arachnida. Arakhan, artificial widening of the forehead by the natives of. Arboricola, young of. Archeopteryx. Arctiidae, coloration of the. Ardea asha, rufescens, and coerulea, change of colour in. Ardea coerulea, breeding in immature plumage. Ardea gularis, change of plumage in. Ardea herodias, love-gestures of the male. Ardea ludoviciana, age of mature plumage in; continued growth of crest and plumes in the male of. Ardea nycticorax, cries of. Ardeola, young of. Ardetta, changes of plumage in. Argenteuil. Argus pheasant, display of plumage by the male; ocellated spots of the; gradation of characters in the. Argyll, Duke of, on the physical weakness of man; the fashioning of implements peculiar to man; on the contest in man between right and wrong; on the primitive civilisation of man; on the plumage of the male Argus pheasant; on Urosticte Benjamini; on the nests of birds. Argynnis, colouring of the lower surface of. Aricoris epitus, sexual differences in the wings of. Aristocracy, increased beauty of the. Arms, proportions of, in soldiers and sailors; direction of the hair on the. Arms and hands, free use of, indirectly correlated with diminution of canines. Arrest of development. Arrow-heads, stone, general resemblance of. Arrows, use of. Arteries, variations in the course of the. Artery, effect of tying, upon the lateral channels. Arthropoda. Arts practised by savages. Ascension, coloured incrustation on the rocks of. Ascidia, affinity of the lancelet to; tad-pole like larvae of. Ascidians, bright colours of some. Asinus, Asiatic and African species of. Asinus taeniopus. Ass, colour-variations of the. Ateles, effects of brandy on an; absence of the thumb in. Ateles beelzebuth, ears of. Ateles marginatus, colour of the ruff of; hair on the head of. Ateuchus cicatricosus, habits of. Ateuchus, stridulation of. Athalia, proportions of the sexes in. Atropus pulsatorius. Attention, manifestations of, in animals. Audouin, V., on a hymenopterous parasite with a sedentary male. Audubon, J.J., on the pinioned goose; on the speculum of Mergus cucullatus; on the pugnacity of male birds; on courtship of Caprimulgus; on Tetrao cupido; on Ardea nycticorax; on Sturnella ludoviciana; on the vocal organs of Tetra cupido; on the drumming of the male Tetrao umbellus; on sounds produced by the nightjar; on Ardea herodias and Cathartes jota; on Mimus polyglottus; on display in male birds; on the spring change of colour in some finches; on migration of mocking thrushes; recognition of a dog by a turkey; selection of mate by female birds; on the turkey; on variation in the male scarlet tanager; on the musk-rat; on the habits of Pyranga aestiva; on local differences in the nests of the same species of birds; on the habits of woodpeckers; on Bombycilla carolinensis; on young females of Pyranga aestiva acquiring male characters; on the immature plumage of thrushes; on the immature plumage of birds; on birds breeding in immature plumage; on the growth of the crest and plume in the male Ardea ludoviciana; on the change of colour in some species of Ardea. Audobon and Bachman, MM., on squirrels fighting; on the Canadian lynx. Aughey, Prof., on rattlesnakes. Austen, N.L., on Anolis cristatellus. Australia, not the birthplace of man; half-castes killed by the natives of; lice of the natives of. Australia, South, variation in the skulls of aborigines of. Australians, colour of new-born children of; relative height of the sexes of; women a cause of war among the. Axis deer, sexual difference in the colour of the. Aymaras, measurements of the; no grey hair among the; hairlessness of the face in the; long hair of the. Azara, on the proportion of men and women among the Guaranys; on Palamedea cornuta; on the beards of the Guaranys; on strife for women among the Guanas; on infanticide; on the eradication of the eyebrows and eyelashes by the Indians of Paraguay; on polyandry among the Guanas; celibacy unknown among the savages of South America; on the freedom of divorce among the Charruas. Babbage C., on the greater proportion of illegitimate female births. Babirusa, tusks of the. Baboon, revenge in a; rage excited in, by reading; manifestation of memory by a; employing a mat for shelter against the sun; protected from punishment by its companions. Baboon, Cape, mane of the male; Hamadryas, mane of the male. Baboon, effects of intoxicating liquors on; ears of; diversity of the mental faculties in; hands of; habits of; variability of the tail in; manifestation of maternal affection by; using stones and sticks as weapons; co-operation of; silence of, on plundering expeditions; apparent polygamy of; polygamous and social habits of. Baboons, courtship of. Bachman, Dr., on the fertility of mulattoes. Baer, K.E. von, on embryonic development; definition of advancement in the organic scale. Bagehot, W., on the social virtues among primitive men; slavery formerly beneficial; on the value of obedience; on human progress; on the persistence of savage tribes in classical times. Bailly, E.M., on the mode of fighting of the Italian buffalo; on the fighting of stags. Bain, A., on the sense of duty; aid springing from sympathy; on the basis of sympathy; on the love of approbation etc.; on the idea of beauty. Baird, W., on a difference in colour between the males and females of some Entozoa. Baker, Mr., observation on the proportion of the sexes in pheasant-chicks. Baker, Sir S., on the fondness of the Arabs for discordant music; on sexual difference in the colours of an antelope; on the elephant and rhinoceros attacking white or grey horses; on the disfigurements practised by the negroes; on the gashing of the cheeks and temples practised in Arab countries; on the coiffure of the North Africans; on the perforation of the lower lip by the women of Latooka; on the distinctive characters of the coiffure of central African tribes; on the coiffure of Arab women. "Balz" of the Black-cock. Bantam, Sebright. Banteng, horns of; sexual differences in the colours of the. Banyai, colour of the. Barbarism, primitive, of civilised nations. Barbs, filamentous, of the feathers, in certain birds. Barr, Mr., on sexual preference in dogs. Barrago, F., on the Simian resemblances of man. Barrington, Daines, on the language of birds; on the clucking of the hen; on the object of the song of birds; on the singing of female birds; on birds acquiring the songs of other birds; on the muscles of the larynx in song-birds; on the want of the power of song by female birds. Barrow, on the widow-bird. Bartels, Dr., supernumerary mammae in men. Bartlett, A.D., period of hatching of bird's eggs; on the tragopan; on the development of the spurs in Crossoptilon auritum; on the fighting of the males of Plectopterus gambensis; on the Knot; on display in male birds; on the display of plumage by the male Polyplectron; on Crossoptilon auritum and Phasianus Wallichii; on the habits of Lophophorus; on the colour of the mouth in Buceros bicornis; on the incubation of the cassowary; on the Cape Buffalo; on the use of the horns of antelopes; on the fighting of male wart-hogs; on Ammotragus tragelaphus; on the colours of Cercopithecus cephus; on the colours of the faces of monkeys; on the naked surfaces of monkeys. Bartlett, on courting of Argus pheasant. Bartram, on the courtship of the male alligator. Basque language, highly artificial. Bate, C.S., on the superior activity of male crustacea; on the proportions of the sexes in crabs; on the chelae of crustacea; on the relative size of the sexes in crustacea; on the colours of crustacea. Bateman, Dr., tendency to imitation in certain diseased states; on Aphasia. Bates, H.W., on variation in the form of the head of Amazonian Indians; on the proportion of the sexes among Amazonian butterflies; on sexual differences in the wings of butterflies; on the field-cricket; on Pyrodes pulcherrimus; on the horns of Lamellicorn beetles; on the colours of Epicaliae, etc.; on the coloration of tropical butterflies; on the variability of Papilio Sesostris and Childrenae; on male and female butterflies inhabiting different stations; on mimicry; on the caterpillar of a Sphinx; on the vocal organs of the umbrella-bird; on the toucans; on Brackyurus calvus. Batokas, knocking out two upper incisors. Batrachia, eagerness of male. Bats, scent-glands; sexual differences in the colour of; fur of male frugivorous. Battle, law of; among beetles; among birds; among mammals; in man. Beak, sexual difference in the forms of the; in the colour of the. Beaks, of birds, bright colours of. Beard, development of, in man; analogy of the, in man and the quadrumana; variation of the development of the, in different races of men; estimation of, among bearded nations; probable origin of the. Beard, in monkeys; of mammals. Beautiful, taste for the, in birds; in the quadrumana. Beauty, sense of, in animals; appreciation of, by birds; influence of; variability of the standard of. Beauty, sense of, sufficiently permanent for action of sexual selection. Beaven, Lieut., on the development of the horns in Cervus Eldi. Beaver, instinct and intelligence of the; voice of the; castoreum of the. Beavers, battles of male. Bechstein, on female birds choosing the best singers among the males; on rivalry in song-birds; on the singing of female birds; on birds acquiring the songs of other birds; on pairing the canary and siskin; on a sub-variety of the monk pigeon; on spurred hens. Beddoe, Dr., on causes of difference in stature. Bee-eater. Bees, pollen-baskets and stings of; destruction of drones and queens by; female, secondary sexual characters of; proportion of sexes; difference of the sexes in colour and sexual selection. Beetle, luminous larva of a. Beetles, size of the cerebral ganglia in; dilatation of the foretarsi in male; blind; stridulation of. Belgium, ancient inhabitants of. Bell, Sir C., on emotional muscles in man; "snarling muscles;" on the hand. Bell, T., on the numerical proportion of the sexes in moles; on the newts; on the croaking of the frog; on the difference in the coloration of the sexes in Zootoca vivipara; on moles fighting. Bell-bird, sexual difference in the colour of the. Bell-birds, colours of. Belt, Mr., on the nakedness of tropical mankind; on a spider-monkey and eagle; habits of ants; Lampridae distasteful to mammals; mimicry of Leptalides; colours of Nicaraguan frogs; display of humming-birds; on the toucans; protective colouring of skunk. Benevolence, manifested by birds. Bennett, A.W., attachment of mated birds; on the habits of Dromaeus irroratus. Bennett, Dr., on birds of paradise. Berbers, fertility of crosses with other races. Bernicla antarctica, colours of. Bernicle gander pairing with a Canada goose. Bert, M., crustaceans distinguish colours. Bettoni, E., on local differences in the nests of Italian birds. Beyle, M., see Bombet. Bhoteas, colour of the beard in. Bhringa, disc-formed tail-feathers of. Bianconi, Prof., on structures as explained through mechanical principles. Bibio, sexual differences in the genus. Bichat, on beauty. Bickes, proportion of sexes in man. Bile, coloured, in many animals. Bimana. Birds, imitations of the songs of other birds by; dreaming; killed by telegraph wires; language of; sense of beauty in; pleasure of, in incubation; male, incubation by; and reptiles, alliance of; sexual differences in the beak of some; migratory, arrival of the male before the female; apparent relation between polygamy and marked sexual differences in; monogamous, becoming polygamous under domestication; eagerness of male in pursuit of the female; wild, numerical proportion of the sexes in; secondary sexual characters of; difference of size in the sexes of; fights of male, witnessed by females; display of male, to captivate the females; close attention of, to the songs of others; acquiring the song of their foster-parents; brilliant, rarely good songsters; love-antics and dances of; coloration of; moulting of; unpaired; male, singing out of season; mutual affection of; in confinement, distinguish persons; hybrid, production of; Albino; European, number of species of; variability of; geographical distribution of colouring; gradation of secondary sexual characters in; obscurely coloured, building concealed nests; young female, acquiring male characters; breeding in immature plumage; moulting of; aquatic, frequency of white plumage in; vocal courtship of; naked skin of the head and neck in. Birgus latro, habits of. Birkbeck, Mr., on the finding of new mates by golden eagles. Birthplace of man. Births, numerical proportions of the sexes in, in animals and man; male and female, numerical proportion of, in England. Bischoff, Prof., on the agreement between the brains of man and of the orang; figure of the embryo of the dog; on the convolutions of the brain in the human foetus; on the difference between the skulls of man and the quadrumana; resemblance between the ape's and man's. Bishop, J., on the vocal organs of frogs; on the vocal organs of cervine birds; on the trachea of the Merganser. Bison, American, co-operation of; mane of the male. Bitterns, dwarf, coloration of the sexes of. Biziura lobata, musky odour of the male; large size of male. Blackbird, sexual differences in the; proportion of the sexes in the; acquisition of a song by; colour of the beak in the sexes of the; pairing with a thrush; colours and nidification of the; young of the; sexual difference in coloration of the. Black-buck, Indian, sexual difference in the colour of the. Blackcap, arrival of the male, before the female; young of the. Black-cock, polygamous; proportion of the sexes in the; pugnacity and love-dance of the; call of the; moulting of the; duration of the courtship of the; and pheasant, hybrids of; sexual difference in coloration of the; crimson eye-cere of the. Black-grouse, characters of young. Blacklock, Dr., on music. Blackwall, J., on the speaking of the magpie; on the desertion of their young by swallows; on the superior activity of male spiders; on the proportion of the sexes in spiders; on sexual variation of colour in spiders; on male spiders. Bladder-nose Seal, hood of the. Blaine, on the affections of dogs. Blair, Dr., on the relative liability of Europeans to yellow fever. Blake, C.C., on the jaw from La Naulette. Blakiston, Captain, on the American snipe; on the dances of Tetrao phasianellus. Blasius, Dr., on the species of European birds. Bledius taurus, hornlike processes of male. Bleeding, tendency to profuse. Blenkiron, Mr., on sexual preference in horses. Blennies, crest developed on the head of male, during the breeding season. Blethisa multipunctata, stridulation of. Bloch, on the proportions of the sexes in fishes. Blood, arterial, red colour of. Blood pheasant, number of spurs in. Blow-fly, sounds made by. Bluebreast, red-throated, sexual differences of the. Blumenbach, on Man; on the large size of the nasal cavities in American aborigines; on the position of man; on the number of species of man. Blyth, E., on the structure of the hand in the species of Hylobates; observations on Indian crows; on the development of the horns in the Koodoo and Eland antelopes; on the pugnacity of the males of Gallicrex cristatus; on the presence of spurs in the female Euplocamus erythrophthalmus; on the pugnacity of the amadavat; on the spoonbill; on the moulting of Anthus; on the moulting of bustards, plovers, and Gallus bankiva; on the Indian honey-buzzard; on sexual differences in the colour of the eyes of hornbills; on Oriolus melanocephalus; on Palaeornis javanicus; on the genus Ardetta; on the peregrine falcon; on young female birds acquiring male characters; on the immature plumage of birds; on representative species of birds; on the young of Turnix; on anomalous young of Lanius rufus and Colymbus glacialis; on the sexes and young of the sparrows; on dimorphism in some herons; on the ascertainment of the sex of nestling bullfinches by pulling out breast-feathers; on orioles breeding in immature plumage; on the sexes and young of Buphus and Anastomus; on the young of the blackcap and blackbird; on the young of the stonechat; on the white plumage of Anastomus; on the horns of Bovine animals; on the horns of Antilope bezoartica; on the mode of fighting of Ovis cycloceros; on the voice of the Gibbons; on the crest of the male wild goat; on the colours of Portax picta; on the colours of Antilope bezoartica; on the colour of the Axis deer; on sexual difference of colour in Hylobates hoolock; on the hog-deer; on the beard and whiskers in a monkey, becoming white with age. Boar, wild, polygamous in India; use of the tusks by the; fighting of. Boardman, Mr., Albino birds in U.S. Boitard and Corbie, MM., on the transmission of sexual peculiarities in pigeons; on the antipathy shewn by some female pigeons to certain males. Bold, Mr., on the singing of a sterile hybrid canary. Bombet, on the variability of the standard of beauty in Europe. Bombus, difference of the sexes in. Bombycidae, coloration of; pairing of the; colours of. Bombycilla carolinensis, red appendages of. Bombyx cynthia, proportion of the sexes in; pairing of. Bombyx mori, difference of size of the male and female cocoons of; pairing of. Bombyx Pernyi, proportion of sexes of. Bombyx Yamamai, M. Personnat on; proportion of sexes of. Bonaparte, C.L., on the call-notes of the wild turkey. Bond, F., on the finding of new mates by crows. Bone, implements of, skill displayed in making. Boner, C., on the transfer of male characters to an old female chamois; on the habits of stags; on the pairing of red deer. Bones, increase of, in length and thickness, when carrying a greater weight. Bonizzi, P., difference of colour in sexes of pigeons. Bonnet monkey. Bonwick, J., extinction of Tasmanians. Boomerang. Boreus hyemalis, scarcity of the male. Bory St. Vincent, on the number of species of man; on the colours of Labrus pavo. Bos etruscus. Bos gaurus, horns of. Bos moschatus. Bos primigenius. Bos sondaicus, horns of, colours of. Botocudos, mode of life of; disfigurement of the ears and lower lip of the. Boucher de Perthes, J.C. de, on the antiquity of man. Bourbon, proportion of the sexes in a species of Papilio from. Bourien on the marriage-customs of the savages of the Malay Archipelago. Bovidae, dewlaps of. Bower-birds, habits of the; ornamented playing-places of. Bows, use of. Brachycephalic structure, possible explanation of. Brachyura. Brachyurus calvus, scarlet face of. Bradley, Mr., abductor ossis metatarsi quinti in man. Brain, of man, agreement of the, with that of lower animals; convolutions of, in the human foetus; influence of development of mental faculties upon the size of the; influence of the development of on the spinal column and skull; larger in some existing mammals than in their tertiary prototypes; relation of the development of the, to the progress of language; disease of the, affecting speech; difference in the convolutions of, in different races of men; supplement on, by Prof. Huxley; development of the gyri and sulci. Brakenridge, Dr., on the influence of climate. Brandt, A., on hairy men. Braubach, Prof., on the quasi-religious feeling of a dog towards his master; on the self-restraint of dogs. Brauer, F., on dimorphism in Neurothemis. Brazil, skulls found in caves of; population of; compression of the nose by the natives of. Break between man and the apes. Bream, proportion of the sexes in the. Breeding, age of, in birds. Breeding season, sexual characters making their appearance in the, in birds. Brehm, on the effects of intoxicating liquors on monkeys; on the recognition of women by male Cynocephali; on the diversity of the mental faculties of monkeys; on the habits of baboons; on revenge taken by monkeys; on manifestations of maternal affection by monkeys and baboons; on the instinctive dread of monkeys for serpents; on the use of stones as missiles by baboons; on a baboon using a mat for shelter from the sun; on the signal-cries of monkeys; on sentinels posted by monkeys; on co-operation of animals; on an eagle attacking a young Cercopithecus; on baboons in confinement protecting one of their number from punishment; on the habits of baboons when plundering; on polygamy in Cynocephalus and Cebus; on the numerical proportion of the sexes in birds; on the love-dance of the blackcock; Palamedea cornuta; on the habits of the Black-grouse; on sounds produced by birds of paradise; on assemblages of grouse; on the finding of new mates by birds; on the fighting of wild boars; on sexual differences in Mycetes; on the habits of Cynocephalus hamadryas. Brent, Mr., on the courtship of fowls. Breslau, numerical proportion of male and female births in. Bridgeman, Laura. Brimstone butterfly, sexual difference of colour in the. British, ancient, tattooing practised by. Broca, Prof., on the occurrence of the supra-condyloid foramen in the human humerus; anthropomorphous apes more bipedal than quadrupedal; on the capacity of Parisian skulls at different periods; comparison of modern and mediaeval skulls; on tails of quadrupeds; on the influence of natural selection; on hybridity in man; on human remains from Les Eyzies; on the cause of the difference between Europeans and Hindoos. Brodie, Sir B., on the origin of the moral sense in man. Bronn, H.G., on the copulation of insects of distinct species. Bronze period, men of, in Europe. Brown, R., sentinels of seals generally females; on the battles of seals; on the narwhal; on the occasional absence of the tusks in the female walrus; on the bladder-nose seal; on the colours of the sexes in Phoca Groenlandica; on the appreciation of music by seals; on plants used as love-philters, by North American women. Browne, Dr. Crichton, injury to infants during parturition. Brown-Sequard, Dr., on the inheritance of the effects of operations by guinea-pig. Bruce, on the use of the elephant's tusks. Brulerie, P. de la, on the habits of Ateuchus cicatricosus; on the stridulation of Ateuchus. Brunnich, on the pied ravens of the Feroe islands. Bryant, Dr., preference of tame pigeon for wild mate. Bryant, Captain, on the courtship of Callorhinus ursinus. Bubas bison, thoracic projection of. Bubalus caffer, use of horns. Bucephalus capensis, difference of the sexes of, in colour. Buceros, nidification and incubation of. Buceros bicornis, sexual differences in the colouring of the casque, beak, and mouth in. Buceros corrugatus, sexual differences in the beak of. Buchner, L., on the origin of man; on the use of the human foot as a prehensile organ; on the mode of progression of the apes; on want of self-consciousness, etc., in savages. Bucholz, Dr., quarrels of chamaeleons. Buckinghamshire, numerical proportion of male and female births in. Buckland, F., on the numerical proportion of the sexes in rats; on the proportion of the sexes in the trout; on Chimaera monstrosa. Buckland, W., on the complexity of crinoids. Buckler, W., proportion of sexes of Lepidoptera reared by. Bucorax abyssinicus, inflation of the neck-wattle of the male during courtship. Budytes Raii. Buffalo, Cape. Buffalo, Indian, horns of the. Buffalo, Italian, mode of fighting of the. Buffon, on the number of species of man. Bufo sikimmensis. Bugs. Buist, R., on the proportion of the sexes in salmon; on the pugnacity of the male salmon. Bulbul, pugnacity of the male; display of under tail-coverts by the male. Bull, mode of fighting of the; curled frontal hair of the. Buller, Dr., on the Huia; the attachment of birds. Bullfinch, sexual differences in the; piping; female, singing of the; courtship of the; widowed, finding a new mate; attacking a reed-bunting; nestling, sex ascertained by pulling out breast feathers. Bullfinches, distinguishing persons; rivalry of female. Bulls, two young, attacking an old one; wild, battles of. Bull-trout, male, colouring of, during the breeding season. Bunting, reed, head feathers of the male; attacked by a bullfinch. Buntings, characters of young. Buphus coromandus, sexes and young of; change of colour in. Burchell, Dr., on the zebra; on the extravagance of a Bushwoman in adorning herself; celibacy unknown among the savages of South Africa; on the marriage-customs of the Bushwomen. Burke, on the number of species of man. Burmese, colour of the beard in. Burton, Captain, on negro ideas of female beauty; on a universal ideal of beauty. Bushmen, marriage among. Bushwoman, extravagant ornamentation of a. Bushwomen, hair of; marriage-customs of. Bustard, throat-pouch of the male; humming noise produced by a male; Indian, ear-tufts of. Bustards, occurrence of sexual differences and of polygamy among the; love-gestures of the male; double moult in. Butler, A.G., on sexual differences in the wings of Aricoris epitus; courtship of butterflies; on the colouring of the sexes in species of Thecla; on the resemblance of Iphias glaucippe to a leaf; on the rejection of certain moths and caterpillars by lizards and frogs. Butterfly, noise produced by a; Emperor; meadow brown, instability of the ocellated spots of. Butterflies, proportion of the sexes in; forelegs atrophied in some males; sexual difference in the neuration of the wings of; pugnacity of male; protective resemblances of the lower surface of; display of the wings by; white, alighting upon bits of paper; attracted by a dead specimen of the same species; courtship of; male and female, inhabiting different stations. Buxton, C., observations on macaws; on an instance of benevolence in a parrot. Buzzard, Indian honey-; variation in the crest of. Cabbage butterflies. Cachalot, large head of the male. Cadences, musical, perception of, by animals. Caecum, large, in the early progenitors of man. Cairina moschata, pugnacity of the male. Californian Indians, decrease of. Callianassa, chelae of, figured. Callidryas, colours of sexes. Callionymus lyra, characters of the male. Callorhinus ursinus, relative size of the sexes of; courtship of. Calotes maria. Calotes nigrilabris, sexual difference in the colour of. Cambridge, O. Pickard, on the sexes of spiders; on the size of male Nephila. Camel, canine teeth of male. Campbell, J., on the Indian elephant; on the proportion of male and female births in the harems of Siam. Campylopterus hemileucurus. Canaries distinguishing persons. Canary, polygamy of the; change of plumage in, after moulting; female, selecting the best singing male; sterile hybrid, singing of a; female, singing of the; selecting a greenfinch; and siskin, pairing of. Cancer pagurus. Canestrini, G., on rudimentary characters and the origin of man; on rudimentary characters; on the movement of the ear in man; of the variability of the vermiform appendage in man; on the abnormal division of the malar bone in man; on abnormal conditions of the human uterus; on the persistence of the frontal suture in man; on the proportion of the sexes in silk-moths; secondary sexual characters of spiders. Canfield, Dr., on the horns of the Antilocapra. Canine teeth in man, diminution of, in man; diminution of, in horses; disappearance of, in male ruminants; large in the early progenitors of man. Canines, and horns, inverse development of. Canoes, use of. Cantharis, difference of colour in the sexes of a species of. Cantharus lineatus. Capercailzie, polygamous; proportion of the sexes in the; pugnacity of the male; pairing of the; autumn meetings of the; call of the; duration of the courtship of; behaviour of the female; inconvenience of black colour to the female; sexual difference in the coloration of the; crimson eye-cere of the male. Capitonidae, colours and nidification of the. Capra aegagrus, crest of the male; sexual difference in the colour of. Capreolus Sibiricus subecaudatus. Caprice, common to man and animals. Caprimulgus, noise made by the males of some species of, with their wings. Caprimulgus virginianus, pairing of. Carabidae. Carbonnier, on the natural history of the pike; on the relative size of the sexes in fishes; courtship of Chinese Macropus. Carcineutes, sexual difference of colour in. Carcinus moenas. Cardinalis virginianus. Carduelis elegans, sexual differences of the beak in. Carnivora, marine, polygamous habits of; sexual differences in the colours of. Carp, numerical proportion of the sexes in the. Carr, R., on the peewit. Carrier pigeon, late development of the wattle in the. Carrion beetles, stridulation of. Carrion-hawk, bright coloured female of. Carus, Prof. V., on the development of the horns in merino sheep; on antlers of red deer. Cassowary, sexes and incubation of the. Castnia, mode of holding wings. Castoreum. Castration, effects of. Casuarius galeatus. Cat, convoluted body in the extremity of the tail of a; sick, sympathy of a dog with a. Cataract in Cebus Azarae. Catarrh, liability of Cebus Azarae to. Catarrhine monkeys. Caterpillars, bright colours of. Cathartes aura. Cathartes jota, love-gestures of the male. Catlin, G., correlation of colour and texture of hair in the Mandans; on the development of the beard among the North American Indians; on the great length of the hair in some North American tribes. Caton, J.D., on the development of the horns in Cervus virginianus and strongyloceros; on the wild turkey; on the presence of traces of horns in the female wapiti; on the fighting of deer; on the crest of the male wapiti; on the colours of the Virginian deer; on sexual differences of colour in the wapiti; on the spots of the Virginian deer. Cats, dreaming; tortoise-shell; enticed by valerian; colours of. Cattle, rapid increase of, in South America; domestic, lighter in winter in Siberia; horns of; domestic, sexual differences of, late developed; numerical proportion of the sexes in. Caudal vertebrae, number of, in macaques and baboons; basal, of monkeys, imbedded in the body. Cavolini, observations on Serranus. Cebus, maternal affection in a; gradation of species of. Cebus Apella. Cebus Azarae, liability of, to the same diseases as man; distinct sounds produced by; early maturity of the female. Cebus capucinus, polygamous; sexual differences of colour in; hair on the head of. Cebus vellerosus, hair on the head of. Cecidomyiidae, proportions of the sexes in. Celibacy, unknown among the savages of South Africa and South America. Centipedes. Cephalopoda, absence of secondary sexual characters in. Cephalopterus ornatus. Cephalopterus penduliger. Cerambyx heros, stridulant organ of. Ceratodus, paddle of. Ceratophora aspera, nasal appendages of. Ceratophora Stoddartii, nasal horn of. Cerceris, habits of. Cercocebus aethiops, whiskers, etc., of. Cercopithecus, young, seized by an eagle and rescued by the troop; definition of species of. Cercopithecus cephus, sexual difference of colour in. Cercopithecus cynosurus and griseo-viridis, colour of the scrotum in. Cercopithecus Diana, sexual differences of colour in. Cercopithecus griseo-viridis. Cercopithecus petaurista, whiskers, etc., of. Ceres, of birds, bright colours of. Ceriornis Temminckii, swelling of the wattles of the male during courtship. Cervulus, weapons of. Cervulus moschatus, rudimentary horns of the female. Cervus alces. Cervus campestris, odour of. Cervus canadensis, traces of horns in the female; attacking a man; sexual difference in the colour of. Cervus elaphus, battles of male; horns of, with numerous points; long hairs on the throat of. Cervus Eldi. Cervus mantchuricus. Cervus paludosus, colours of. Cervus strongyloceros. Cervus virginianus, horns of, in course of modification. Ceryle, male black-belted in some species of. Cetacea, nakedness of. Ceylon, frequent absence of beard in the natives of. Chaffinch, proportion of the sexes in the; courtship of the. Chaffinches, new mates found by. Chalcophaps indicus, characters of young. Chalcosoma atlas, sexual differences of. Chamaeleo, sexual differences in the genus; combats of. Chamaeleo bifurcus. Chamaeleo Owenii. Chamaeleo pumilus. Chamaepetes unicolor, modified wing-feather in the male. Chameleons. Chamois, danger-signals of; transfer of male characters to an old female. Champneys, Mr., acromio-basilar muscle and quadrupedal gait. Chapman, Dr., on stridulation in Scolytus. Chapuis, Dr., on the transmission of sexual peculiarities in pigeons; on streaked Belgian pigeons. Char, male, colouring of, during the breeding season. Characters, male, developed in females; secondary sexual, transmitted through both sexes; natural, artificial, exaggeration of, by man. Charadrus hiaticula and pluvialis, sexes and young of. Chardin on the Persians. Charms, worn by women. Charruas, freedom of divorce among the. Chasmorhynchus, difference of colour in the sexes of; colours of. Chasmorhynchus niveus. Chasmorhynchus nudicollis. Chasmorhynchus tricarunculatus. Chastity, early estimation of. Chatterers, sexual differences in. Cheever, Rev. H.T., census of the Sandwich Islands. Cheiroptera, absence of secondary sexual characters in. Chelae of crustacea. Chelonia, sexual differences in. Chenalopex aegyptiacus, wing-knobs of. Chera progne. Chest, proportions of, in soldiers and sailors; large, of the Quechua and Aymara Indians. Chevrotains, canine teeth of. Chiasognathus, stridulation of. Chiasognathus Grantii, mandibles of. Children, legitimate and illegitimate, proportion of the sexes in. Chiloe, lice of the natives of; population of. Chimaera monstrosa, bony process on the head of the male. Chimaeroid fishes, prehensile organs of male. Chimpanzee, ears of the; representatives of the eyebrows in the; hands of the; absence of mastoid processes in the; platforms built by the; cracking nuts with a stone; direction of the hair on the arms of the; supposed evolution of the; polygamous and social habits of the. China, North, idea of female beauty in. China, Southern, inhabitants of. Chinese, use of flint tools by the; difficulty of distinguishing the races of the; colour of the beard in; general beardlessness of the; opinions of the, on the appearance of Europeans and Cingalese; compression of the feet of. Chinsurdi, his opinion of beards. Chlamydera maculata. Chloeon, pedunculated eyes of the male of. Chloephaga, coloration of the sexes in. Chlorocoelus Tanana. Chorda dorsalis. Chough, red beak of the. Chromidae, frontal protuberance in male; sexual differences in colour of. Chrysemys picta, long claws of the male. Chrysococcyx, characters of young of. Chrysomelidae, stridulation of. Cicada pruinosa. Cicada septendecim. Cicadae, songs of the; rudimentary sound-organs in females of. Cicatrix of a burn, causing modification of the facial bones. Cichla, frontal protuberance of male. Cimetiere du Sud, Paris. Cincloramphus cruralis, large size of male. Cinclus aquaticus. Cingalese, Chinese opinion of the appearance of the. Cirripedes, complemental males of. Civilisation, effects of, upon natural selection; influence of, in the competition of nations. Clanging of geese, etc. Claparede, E., on natural selection applied to man. Clarke, on the marriage-customs of Kalmucks. Classification. Claus, C., on the sexes of Saphirina. Cleft-palate, inherited. Climacteris erythrops, sexes of. Climate, cool, favourable to human progress; power of supporting extremes of, by man; want of connexion of, with colour; direct action of, on colours of birds. Cloaca, existence of a, in the early progenitors of man. Cloacal passage existing in the human embryo. Clubs, used as weapons before dispersion of mankind. Clucking of fowls. Clythra 4-punctata, stridulation of. Coan, Mr., Sandwich-islanders. Cobbe, Miss, on morality in hypothetical bee-community. Cobra, ingenuity of a. Coccus. Coccyx, in the human embryo; convoluted body at the extremity of the; imbedded in the body. Cochin-China, notions of beauty of the inhabitants of. Cock, blind, fed by its companion; game, killing a kite; comb and wattles of the; preference shewn by the, for young hens; game, transparent zone in the hackles of a. Cock of the rock. Cockatoos, nestling; black, immature plumage of. Coelenterata, absence of secondary sexual characters in. Coffee, fondness of monkeys for. Cold, supposed effects of; power of supporting, by man. Coleoptera, stridulation of; stridulant organs of, discussed. Colias edusa and hyale. Collingwood, C., on the pugnacity of the butterflies of Borneo; on butterflies being attracted by a dead specimen of the same species. Colobus, absence of the thumb. Colombia, flattened heads of savages of. Colonists, success of the English as. Coloration, protective, in birds. Colour, supposed to be dependent on light and heat; correlation of, with immunity from certain poisons and parasites; purpose of, in lepidoptera; relation of, to sexual functions, in fishes; difference of, in the sexes of snakes; sexual differences of, in lizards; influence of, in the pairing of birds of different species; relation of, to nidification; sexual differences of, in mammals; recognition of, by quadrupeds; of children, in different races of man; of the skin in man. Colours, admired alike by man and animals; bright, due to sexual selection; bright, among the lower animals; bright, protective to butterflies and moths; bright, in male fishes; transmission of, in birds. Colquhoun, example of reasoning in a retriever. Columba passerina, young of. Colymbus glacialis, anomalous young of. Comb, development of, in fowls. Combs and wattles in male birds. Community, preservation of variations useful to the, by natural selection. Complexion, different in men and women, in an African tribe. Compositae, gradation of species among the. Comte, C., on the expression of the ideal of beauty by sculpture. Conditions of life, action of changed, upon man; influence of, on plumage of birds. Condor, eyes and comb of the. Conjugations, origin of. Conscience, absence of, in some criminals. Constitution, difference of, in different races of men. Consumption, liability of Cebus Azarae to; connection between complexion and. Convergence of characters. Cooing of pigeons and doves. Cook, Captain, on the nobles of the Sandwich Islands. Cope, E.D., on the Dinosauria. Cophotis ceylanica, sexual differences of. Copris. Copris Isidis, sexual differences of. Copris lunaris, stridulation of. Corals, bright colours of. Coral-snakes. Cordylus, sexual difference of colour in a species of. Corfu, habits of the Chaffinch in. Cornelius, on the proportions of the sexes in Lucanus Cervus. Corpora Wolffiana, agreement of, with the kidneys of fishes. Correlated variation. Correlation, influence of, in the production of races. Corse, on the mode of fighting of the elephant. Corvus corone. Corvus graculus, red beak of. Corvus pica, nuptial assembly of. Corydalis cornutus, large jaws of the male. Cosmetornis. Cosmetornis vexillarius, elongation of wing-feathers in. Cotingidae, sexual differences in; coloration of the sexes of; resemblance of the females of distinct species of. Cottus scorpius, sexual differences in. Coulter, Dr., on the Californian Indians. Counting, origin of; limited power of, in primeval man. Courage, variability of, in the same species; universal high appreciation of; importance of; characteristic of men. Courtship, greater eagerness of males in; of fishes; of birds. Cow, winter change of colour. Crab, devil. Crab, shore, habits of. Crabro cribrarius, dilated tibiae of the male. Crabs, proportions of the sexes in. Cranz, on the inheritance of dexterity in seal-catching. Crawfurd, on the number of species of man. Crenilabrus massa and C. melops, nests, built by. Crest, origin of, in Polish fowls. Crests, of birds, difference of, in the sexes; dorsal hairy, of mammals. Cricket, field-, stridulation of the; pugnacity of male. Cricket, house-, stridulation of the. Crickets, sexual differences in. Crinoids, complexity of. Crioceridae, stridulation of the. Croaking of frogs. Crocodiles, musky odour of, during the breeding season. Crocodilia. Crossbills, characters of young. Crosses in man. Crossing of races, effects of the. Crossoptilon auritum, adornment of both sexes of; sexes alike in. Crotch, G.R., on the stridulation of beetles; on the stridulation of Heliopathes; on the stridulation of Acalles; habit of female deer at breeding time. Crow, Indians, long hair of the. Crow, young of the. Crows, vocal organs of the; living in triplets. Crows, carrion, new mates found by. Crows, Indian, feeding their blind companions. Cruelty of savages to animals. Crustacea, parasitic, loss of limbs by female; prehensile feet and antennae of; male, more active than female; parthenogenesis in; secondary sexual characters of; amphipod, males sexually mature while young; auditory hairs of. Crystal worn in the lower lip by some Central African women. Cuckoo fowls. Culicidae, attracted by each other's humming. Cullen, Dr., on the throat-pouch of the male bustard. Cultivation of plants, probable origin of. Cupples, Mr., on the numerical proportion of the sexes in dogs, sheep, and cattle; on the Scotch deerhound; on sexual preference in dogs. Curculionidae, sexual difference in length of snout in some; hornlike processes in male; musical. Curiosity, manifestations of, by animals. Curlews, double moult in. Cursores, comparative absence of sexual differences among the. Curtis, J., on the proportion of the sexes in Athalia. Cuvier, F., on the recognition of women by male quadrumana. Cuvier, G., on the number of caudal vertebrae in the mandrill; on instinct and intelligence; views of, as to the position of man; on the position of the seals; on Hectocotyle. Cyanalcyon, sexual difference in colours of; immature plumage of. Cyanecula suecica, sexual differences of. Cychrus, sounds produced by. Cycnia mendica, sexual difference of, in colour. Cygnus ferus, trachea of. Cygnus immutabilis. Cygnus olor, white young of. Cyllo Leda, instability of the ocellated spots of. Cynanthus, variation in the genus. Cynipidae, proportion of the sexes in. Cynocephalus, difference of the young from the adult; male, recognition of women by; polygamous habits of species of. Cynocephalus babouin. Cynocephalus chacma. Cynocephalus gelada. Cynocephalus hamadryas, sexual difference of colour in. Cynocephalus leucophaeus, colours of the sexes of. Cynocephalus mormon, colours of the male. Cynocephalus porcarius, mane of the male. Cynocephalus sphinx. Cynopithecus niger, ear of. Cypridina, proportions of the sexes in. Cyprinidae, proportion of the sexes in the. Cyprinidae, Indian. Cyprinodontidae, sexual differences in the. Cyprinus auratus. Cypris, relation of the sexes in. Cyrtodactylus rubidus. Cystophora cristata, hood of. Dacelo, sexual difference of colour in. Dacelo Gaudichaudi, young male of. Dal-ripa, a kind of ptarmigan. Damalis albifrons, peculiar markings of. Damalis pygarga, peculiar markings of. Dampness of climate, supposed influence of, on the colour of the skin. Danaidae. Dances of birds. Dancing, universality of. Danger-signals of animals. Daniell, Dr., his experience of residence in West Africa. Darfur, protuberances artificially produced by natives of. Darwin, F., on the stridulation of Dermestes murinus. Dasychira pudibunda, sexual difference of colour in. Davis, A.H., on the pugnacity of the male stag-beetle. Davis, J.B., on the capacity of the skull in various races of men; on the beards of the Polynesians. Death's Head Sphinx. Death-rate higher in towns than in rural districts. Death-tick. De Candolle, Alph., on a case of inherited power of moving the scalp. Declensions, origin of. Decoration in birds. Decticus. Deer, development of the horns in; spots of young; horns of; use of horns of; horns of a, in course of modification; size of the horns of; female, pairing with one male whilst others are fighting for her; male, attracted by the voice of the female; male, odour emitted by. Deer, Axis, sexual difference in the colour of the. Deer, fallow, different coloured herds of. Deer, Mantchurian. Deer, Virginian, colour of the, not affected by castration; colours of. Deerhound, Scotch, greater size of the male. Defensive orders of mammals. De Geer, C., on a female spider destroying a male. Dekay, Dr., on the bladder-nose seal. Delorenzi, G., division of malar bone. Demerara, yellow fever in. Dendrocygna. Dendrophila frontalis, young of. Denison, Sir W., manner of ridding themselves of vermin among the Australians; extinction of Tasmanians. Denny, H., on the lice of domestic animals. Dermestes murinus, stridulation of. Descent traced through the mother alone. Deserts, protective colouring of animals inhabiting. Desmarest, on the absence of suborbital pits in Antilope subgutturosa; on the whiskers of Macacus; on the colour of the opossum; on the colours of the sexes of Mus minutus; on the colouring of the ocelot; on the colours of seals; on Antilope caama; on the colours of goats; on sexual difference of colour in Ateles marginatus; on the mandrill; on Macacus cynomolgus. Desmoulins, on the number of species of man; on the muskdeer. Desor, on the imitation of man by monkeys. Despine, P., on criminals destitute of conscience. Development, embryonic of man; correlated. Devil, not believed in by the Fuegians. Devil-crab. Devonian, fossil-insect from the. Dewlaps, of Cattle and antelopes. Diadema, sexual differences of colouring in the species of. Diamond-beetles, bright colours of. Diastema, occurrence of, in man. Diastylidae, proportion of the sexes in. Dicrurus, racket-shaped feathers in; nidification of. Dicrurus macrocercus, change of plumage in. Didelphis opossum, sexual difference in the colour of. Differences, comparative, between different species of birds of the same sex. Digits, supernumerary, more frequent in men than in women; supernumerary, inheritance of; supernumerary, early development of. Dimorphism, in females of water-beetles; in Neurothemis and Agrion. Diodorus, on the absence of beard in the natives of Ceylon. Dipelicus Cantori, sexual differences of. Diplopoda, prehensile limbs of the male. Dipsas cynodon, sexual difference in the colour of. Diptera. Disease, generated by the contact of distinct peoples. Diseases, common to man and the lower animals; difference of liability to, in different races of men; new, effects of, upon savages; sexually limited. Display, coloration of Lepidoptera for; of plumage by male birds. Distribution, wide, of man; geographical, as evidence of specific distinctness in man. Disuse, effects of, in producing rudimentary organs; and use of parts, effects of; of parts, influence of, on the races of men. Divorce, freedom of, among the Charruas. Dixon, E.S., on the pairing of different species of geese; on the courtship of peafowl. Dobrizhoffer, on the marriage-customs of the Abipones. Dobson, Dr., on the Cheiroptera; scent-glands of bats; frugivorous bats. Dogs, suffering from tertian ague; memory of; dreaming; diverging when drawing sledges over thin ice; exercise of reasoning faculties by; domestic, progress of, in moral qualities; distinct tones uttered by; parallelism between his affection for his master and religious feeling; sociability of the; sympathy of, with a sick cat; sympathy of, with his master; their possession of conscience; possible use of the hair on the fore-legs of the; races of the; numerical proportion of male and female births in; sexual affection between individuals of; howling at certain notes; rolling in carrion. Dolichocephalic structure, possible cause of. Dolphins, nakedness of. Domestic animals, races of; change of breeds of. Domestication, influence of, in removing the sterility of hybrids. D'Orbigny, A., on the influence of dampness and dryness on the colour of the skin; on the Yuracaras. Dotterel. Doubleday, E., on sexual differences in the wings of butterflies. Doubleday, H., on the proportion of the sexes in the smaller moths; males of Lasiocampa quercus and on the attraction of the Saturnia carpini by the female; on the proportion of the sexes in the Lepidoptera; on the ticking of Anobium tesselatum; on the structure of Ageronia feronia; on white butterflies alighting upon paper. Douglas, J.W., on the sexual differences of the Hemiptera; colours of British Homoptera. Down, of birds. Draco, gular appendages of. Dragonet, Gemmeous. Dragon-flies, caudal appendages of male; relative size of the sexes of; difference in the sexes of; want of pugnacity by the male. Drake, breeding plumage of the. Dreams, possible source of the belief in spiritual agencies. Drill, sexual difference of colour in the. Dromaeus irroratus. Dromolaea, Saharan species of. Drongo shrike. Drongos, racket-shaped feathers in the tails of. Dryness of climate, supposed influence of, on the colour of the skin. Dryopithecus. Duck, harlequin, age of mature plumage in the; breeding in immature plumage. Duck, long-tailed, preference of male, for certain females. Duck, pintail, pairing with a widgeon. Duck, voice of the; pairing with a shield-drake; immature plumage of the. Duck, wild, sexual differences in the; speculum and male characters of; pairing with a pin-tail drake. Ducks, wild, becoming polygamous under partial domestication; dogs and cats recognised by. Dufosse, Dr., sounds produced by fish. Dugong, nakedness of; tusks of. Dujardin, on the relative size of the cerebral ganglia, in insects. Duncan, Dr., on the fertility of early marriages; comparative health of married and single. Dupont, M., on the occurrence of the supra-condyloid foramen in the humerus of man. Durand, J.P., on causes of variation. Dureau de la Malle, on the songs of birds; on the acquisition of an air by blackbirds. Dutch, retention of their colour by the, in South Africa. Duty, sense of. Duvaucel, female Hylobates washing her young. Dyaks, pride of, in mere homicide. Dynastes, large size of males of. Dynastini, stridulation of. Dytiscus, dimorphism of females of; grooved elytra of the female. Eagle, young Cercopithecus rescued from, by the troop. Eagle, white-headed, breeding in immature plumage. Eagles, golden, new mates found by. Ear, motion of the; external shell of the, useless in man; rudimentary point of the, in man. Ears, more variable in men than women; piercing and ornamentation of the. Earwigs, parental feeling in. Echidna. Echini, bright colours of some. Echinodermata, absence of secondary sexual characters in. Echis carinata. Ecker, figure of the human embryo; on the development of the gyri and sulci of the brain; on the sexual differences in the pelvis in man; on the presence of a sagittal crest in Australians. Edentata, former wide range of, in America; absence of secondary sexual characters in. Edolius, racket-shaped feathers in. Edwards, Mr., on the proportion of the sexes in North American species of Papilio. Eels, hermaphroditism of. Egerton, Sir P., on the use of the antlers of deer; on the pairing of red deer; on the bellowing of stags. Eggs, hatched by male fishes. Egret, Indian, sexes and young of. Egrets, breeding plumage of; white. Ehrenberg, on the mane of the male Hamadryas baboon. Ekstrom, M., on Harelda glacialis. Elachista rufocinerea, habits of male. Eland, development of the horns of the. Elands, sexual differences of colour in. Elaphomyia, sexual differences in. Elaphrus uliginosus, stridulation of. Elaps. Elateridae, proportion of the sexes in. Elaters, luminous. Elephant, rate of increase of the; nakedness of the; using a fan; Indian, forbearance to his keeper; polygamous habits of the; pugnacity of the male; tusks of; Indian, mode of fighting of the; male, odour emitted by the; attacking white or grey horses. Elevation of abode, modifying influence of. Elimination of inferior individuals. Elk, winter change of the. Elk, Irish, horns of the. Ellice Islands, beards of the natives. Elliot, D.G., on Pelecanus erythrorhynchus. Elliot, R., on the numerical proportion of the sexes in young rats; on the proportion of the sexes in sheep. Elliot, Sir W., on the polygamous habits of the Indian wild boar. Ellis, on the prevalence of infanticide in Polynesia. Elphinstone, Mr., on local difference of stature among the Hindoos; on the difficulty of distinguishing the native races of India. Elytra, of the females of Dytiscus Acilius, Hydroporus. Emberiza, characters of young. Emberiza miliaria. Emberiza schoeniclus, head-feathers of the male. Embryo of man; of the dog. Embryos of mammals, resemblance of the. Emigration. Emotions experienced by the lower animals in common with man; manifested by animals. Emperor butterfly. Emperor moth. Emu, sexes and incubation of. Emulation of singing birds. Endurance, estimation of. Energy, a characteristic of men. England, numerical proportion of male and female births in. Engleheart, Mr., on the finding of new mates by starlings. English, success of, as colonists. Engravers, short-sighted. Entomostraca. Entozoa, difference of colour between the males and females of some. Environment, direct action of the, in causing differences between the sexes. Envy, persistence of. Eocene period, possible divergence of men during the. Eolidae, colours of, produced by the biliary glands. Epeira nigra, small size of the male of. Ephemerae. Ephemeridae. Ephippiger vitium, stridulating organs of. Epicalia, sexual differences of colouring in the species of. Equus hemionus, winter change of. Erateina, coloration of. Ercolani, Prof., hermaphroditism in eels. Erect attitude of man. Eristalis, courting of. Eschricht, on the development of hair in man; on a languinous moustache in a female foetus; on the want of definition between the scalp and the forehead in some children; on the arrangement of the hair in the human foetus; on the hairiness of the face in the human foetus of both sexes. Esmeralda, difference of colour in the sexes of. Esox lucius. Esox reticulatus. Esquimaux, their belief in the inheritance of dexterity in seal-catching; mode of life of. Estrelda amandava, pugnacity of the male. Eubagis, sexual differences of colouring in the species of. Euchirus longimanus, sound produced by. Eudromias morinellus. Eulampis jugularis, colours of the female. Euler, on the rate of increase in the United States. Eunomota superciliaris, racket-shaped feathers in the tail of. Eupetomena macroura, colours of the female. Euphema splendida. Euplocamus erythrophthalmus, possession of spurs by the female. Europe, ancient inhabitants of. Europeans, difference of, from Hindoos; hairiness of, probably due to reversion. Eurostopodus, sexes of. Eurygnathus, different proportions of the head in the sexes of. Eustephanus, sexual differences of species of; young of. Exaggeration of natural characters by man. Exogamy. Experience, acquisition of, by animals. Expression, resemblances in, between man and the apes. Extinction of races, causes of. Eye, destruction of the; change of position in; obliquity of, regarded as a beauty by the Chinese and Japanese. Eyebrows, elevation of; development of long hairs in; in monkeys; eradicated in parts of South America and Africa; eradication of, by the Indians of Paraguay. Eyelashes, eradication of, by the Indians of Paraguay. Eyelids, coloured black, in part of Africa. Eyes, pillared, of the male of Chloeon; difference in the colour of, in the sexes of birds. Eyton, T.C., observations on the development of the horns in the fallow deer. Eyzies, Les, human remains from. Fabre, M., on the habits of Cerceris. Facial bones, causes of modification of the. Faculties, diversity of, in the same race of men; inheritance of; diversity of, in animals of the same species; mental variation of, in the same species; of birds. Fakirs, Indian, tortures undergone by. Falco leucocephalus. Falco peregrinus. Falco tinnunclus. Falcon, peregrine, new mate found by. Falconer, H., on the mode of fighting of the Indian elephant; on canines in a female deer; on Hyomoschus aquaticus. Falkland Islands, horses of. Fallow-deer, different coloured herds of. Famines, frequency of, among savages. Farr, Dr., on the effects of profligacy; on the influence of marriage on mortality. Farrar, F.W., on the origin of language; on the crossing or blending of languages; on the absence of the idea of God in certain races of men; on early marriages of the poor; on the middle ages. Farre, Dr., on the structure of the uterus. Fashions, long prevalence of, among savages. Faye, Prof., on the numerical proportion of male and female births in Norway and Russia; on the greater mortality of male children at and before birth. Feathers, modified, producing sounds; elongated, in male birds; racket-shaped; barbless and with filamentous barbs in certain birds; shedding of margins of. Feeding, high, probable influence of, in the pairing of birds of different species. Feet, thickening of the skin on the soles of the; modification of, in man. Felis canadensis, throat-ruff of. Felis pardalis and F. mitis, sexual difference in the colouring of. Female, behaviour of the, during courtship. Female birds, differences of. Females, presence of rudimentary male organs in; preference of, for certain males; pursuit of, by males; occurrence of secondary sexual characters in; development of male character by. Females and males, comparative numbers of; comparative mortality of, while young. Femur and tibia, proportions of, in the Aymara Indians. Fenton, Mr., decrease of Maories; infanticide amongst the Maories. Ferguson, Mr., on the courtship of fowls. Fertilisation, phenomena of, in plants; in the lower animals. Fertility lessened under changed conditions. Fevers, immunity of Negroes and Mulattoes from. Fiber zibethicus, protective colouring of it. Fick, H., effect of conscription for military service. Fidelity, in the elephant; of savages to one another; importance of. Field-slaves, difference of, from house-slaves. Fiji Archipelago, population of the. Fiji Islands, beards of the natives; marriage-customs of the. Fijians, burying their old and sick parents alive; estimation of the beard among the; admiration of, for a broad occiput. Filial affection, partly the result of natural selection. Filum terminale. Finch, racket-shaped feathers in the tail of a. Finches, spring change of colour in; British, females of the. Fingers, partially coherent, in species of Hylobates. Finlayson, on the Cochin Chinese. Fire, use of. Fischer, on the pugnacity of the male of Lethrus cephalotes. Fischer, F. Von, on display of brightly coloured parts by monkeys in courtship. Fish, eagerness of male; proportion of the sexes in; sounds produced by. Fishes, kidneys of, represented by Corpora Wolffiana in the human embryo; male, hatching ova in their mouths; receptacles for ova possessed by; relative size of the sexes in; fresh-water, of the tropics; protective resemblances in; change of colour in; nest-building; spawning of; sounds produced by; continued growth of. Flamingo, age of mature plumage. Flexor pollicis longus, similar variation of, in man. Flies, humming of. Flint tools. Flints, difficulty of chipping into form. Florida, Quiscalus major in. Florisuga mellivora. Flounder, coloration of the. Flower, W.H., on the abductor of the fifth metatarsal in apes; on the position of the Seals; on the Pithecia monachu; on the throat-pouch of the male bustard. Fly-catchers, colours and nidification of. Foetus, human, woolly covering of the; arrangement of the hair on. Food, influence of, upon stature. Foot, prehensile power of the, retained in some savages; prehensile, in the early progenitors of man. Foramen, supra-condyloid, exceptional occurrence of in the humerus of man; in the early progenitors of man. Forbes, D., on the Aymara Indians; on local variation of colour in the Quichuas; on the hairlessness of the Aymaras and Quichuas; on the long hair of the Aymaras and Quichaus. Forel, F., on white young swans. Forester, Hon. O.W., on an orphan hawk. Formica rufa, size of the cerebral ganglia in. Fossils, absence of, connecting man with the apes. Fowl, occurrence of spurs in the female; game, early pugnacity of; Polish, early development of cranial peculiarities of; variations in plumage of; examples of correlated development in the; domestic, breeds and sub-breeds of. Fowls, spangled Hamburg; inheritance of changes of plumage by; sexual peculiarities in, transmitted only to the same sex; loss of secondary sexual characters by male; Polish, origin of the crest in; period of inheritance of characters by; cuckoo-; development of the comb in; numerical proportion of the sexes in; courtship of; mongrel, between a black Spanish cock and different hens; pencilled Hamburg, difference of the sexes in; Spanish, sexual differences of the comb in; spurred, in both sexes. Fox, W.D., on some half-tamed wild ducks becoming polygamous, and on polygamy in the guinea-fowl and canary-bird; on the proportion of the sexes in cattle; on the pugnacity of the peacock; on a nuptial assembly of magpies; on the finding of new mates by crows; on partridges living in triplets; on the pairing of a goose with a Chinese gander. Foxes, wariness of young, in hunting districts; black. Fraser, C., on the different colours of the sexes in a species of Squilla. Fraser, G., colours of Thecla. Frere, Hookham, quoting Theognis on selection in mankind. Fringilla cannabina. Fringilla ciris, age of mature plumage in. Fringilla cyanea, age of mature plumage in. Fringilla leucophrys, young of. Fringilla spinus. Fringilla tristis, change of colour in, in spring; young of. Fringillidae, resemblance of the females of distinct species of. Frog, bright coloured and distasteful to birds. Frogs, male; temporary receptacles for ova possessed by; ready to breed before the females; fighting of; vocal organs of. Frontal bone, persistence of the suture in. Fruits, poisonous, avoided by animals. Fuegians, difference of stature among the; power of sight in the; skill of, in stone-throwing; resistance of the, to their severe climate; mental capacity of the; quasi-religious sentiments of the; resemblance of, in mental characters, to Europeans; mode of life of the; aversion of, to hair on the face; said to admire European women. Fulgoridae, songs of the. Fur, whiteness of, in Arctic animals in winter. Fur-bearing animals, acquired sagacity of. Gallicrex, sexual difference in the colour of the irides in. Gallicrex cristatus, pugnacity of male; red carbuncle occurring in the male during the breeding-season. Gallinaceae, frequency of polygamous habits and of sexual differences in the; love-gestures of; decomposed feathers in; stripes of young; comparative sexual differences between the species of; plumage of. Gallinaceous birds, weapons of the male; racket-shaped feathers on the heads of. Gallinula chloropus, pugnacity of the male. Galloperdix, spurs of; development of spurs in the female. Gallophasis, young of. Galls. Gallus bankiva, neck-hackles of. Gallus Stanleyi, pugnacity of the male. Galton, Mr., on hereditary genius; gregariousness and independence in animals; on the struggle between the social and personal impulses; on the effects of natural selection on civilised nations; on the sterility of sole daughters; on the degree of fertility of people of genius; on the early marriages of the poor; on the ancient Greeks; on the Middle Ages; on the progress of the United States; on South African notions of beauty. Gammarus, use of the chelae of. Gammarus marinus. Gannets, white only when mature. Ganoid fishes. Gaour, horns of the. Gap between man and the apes. Gaper, sexes and young of. Gardner, on an example of rationality in a Gelasimus. Garrulus glandarius. Gartner, on sterility of hybrid plants. Gasteropoda, pulmoniferous, courtship of. Gasterosteus, nidification of. Gasterosteus leiurus. Gasterosteus trachurus. Gastrophora, wings of, brightly coloured beneath. Gauchos, want of humanity among the. Gaudry, M., on a fossil monkey. Gavia, seasonal change of plumage in. Geese, clanging noise made by; pairing of different species of; Canada, selection of mates by. Gegenbaur, C., on the number of digits in the Ichthyopterygia; on the hermaphroditism of the remote progenitors of the vertebrata; two types of nipple in mammals. Gelasimus, proportions of the sexes in a species of; use of the enlarged chelae of the male; pugnacity of males of; rational actions of a; difference of colour in the sexes of a species of. Gemmules, dormant in one sex. Genius, hereditary. Genius, fertility of men and women of. Geoffroy St.-Hilaire, Isid., on the recognition of women by male quadrumana; on monstrosities; coincidences of arrested development with polydactylism; on animal-like anomalies in the human structure; on the correlation of monstrosities; on the distribution of hair in man and monkeys; on the caudal vertebrae of monkeys; on correlated variability; on the classification of man; on the long hair on the heads of species of Semnopithecus; on the hair in monkeys; on the development of horns in female deer; and F. Cuvier, on the mandrill; on Hylobates. Geographical distribution, as evidence of specific distinctions in man. Geometrae, brightly coloured beneath. Geophagus, frontal protuberance of, male; eggs hatched by the male, in the mouth or branchial cavity. Georgia, change of colour in Germans settled in. Geotrupes, stridulation of. Gerbe, M., on the nest-building of Crenilabus massa and C. Melops. Gerland, Dr., on the prevalence of infanticide; on the extinction of races. Gervais, P., on the hairiness of the gorilla; on the mandrill. Gesture-language. Ghost-moth, sexual difference of colour in the. Giard, M., disputes descent of vertebrates from Ascidians; colour of sponges and Ascidians; musky odour of Sphinx. Gibbon, voice of. Gibbon, Hoolock, nose of. Gibbs, Sir D., on differences of the voice in different races of men. Gill, Dr., male seals larger than females; sexual differences in seals. Giraffe, its mode of using the horns; mute, except in the rutting season. Giraud-Teulon, on the cause of short sight. Glanders, communicable to man from the lower animals. Glands, odoriferous, in mammals. Glareola, double moult in. Glomeris limbata, difference of colour in the sexes of. Glow-worm, female, apterous; luminosity of the. Gnats, dances of; auditory powers of. Gnu, skeletons of, found locked together; sexual differences in colour of the. Goat, male, wild, falling on his horns; male, odour emitted by; male, wild, crest of the; Berbura, mane, dewlap, etc., of the male; Kemas, sexual difference in the colour of the. Goats, sexual differences in the horns of; horns of; mode of fighting of; domestic, sexual differences of, late developed; beards of. Goatsucker, Virginian, pairing of the. Gobies, nidification of. God, want of the idea of, in some races of men. Godron, M., on variability; on difference of stature; on the want of connexion between climate and the colour of the skin; on the colour of the skin; on the colour of infants. Goldfinch, proportion of the sexes in the; sexual differences of the beak in the; courtship of the. Goldfinch, North American, young of. Goldfish. Gomphus, proportions of the sexes in; difference in the sexes of. Gonepteryx Rhamni, sexual difference of colour in. Goodsir, Prof., on the affinity of the lancelet to the ascidians. Goosander, young of. Goose, Antarctic, colours of the. Goose, Canada, pairing with a Bernicle gander. Goose, Chinese, knob on the beak of the. Goose, Egyptian. Goose, Sebastopol, plumage of. Goose, Snow-, whiteness of the. Goose, Spur-winged. Gorilla, semi-erect attitude of the; mastoid processes of the; protecting himself from rain with his hands; manner of sitting; supposed to be a kind of mandrill; polygamy of the; voice of the; cranium of; fighting of male. Gosse, P.H., on the pugnacity of the male Humming-bird. Gosse, M., on the inheritance of artificial modifications of the skull. Gould, B.A., on variation in the length of the legs in man; measurements of American soldiers; on the proportions of the body and capacity of the lungs in different races of men; on the inferior vitality of mulattoes. Gould, J., on migration of swifts; on the arrival of male snipes before the females; on the numerical proportion of the sexes in birds; on Neomorpha Grypus; on the species of Eustephanus; on the Australian musk-duck; on the relative size of the sexes in Briziura lobata and Cincloramphus cruralis; on Lobivanellus lobatus; on habits of Menura Alberti; on the rarity of song in brilliant birds; on Selasphorus platycerus; on the Bower-birds; on the ornamental plumage of the Humming-birds; on the moulting of the ptarmigan; on the display of plumage by the male Humming-birds; on the shyness of adorned male birds; on the decoration of the bowers of Bower-birds; on the decoration of their nest by Humming-birds; on variation in the genus Cynanthus; on the colour of the thighs in a male parrakeet; on Urosticte Benjamini; on the nidification of the Orioles; on obscurely-coloured birds building concealed nests; on trogons and king-fishers; on Australian parrots; on Australian pigeons; on the moulting of the ptarmigan; on the immature plumage of birds; on the Australian species of Turnix; on the young of Aithurus polytmus; on the colours of the bills of toucans; on the relative size of the sexes in the marsupials of Australia; on the colours of the Marsupials. Goureaux, on the stridulation of Mutilla europaea. Gout, sexually transmitted. Graba, on the Pied Ravens of the Feroe Islands; variety of the Guillemot. Gradation of secondary sexual characters in birds. Grallatores, absence of secondary sexual characters in; double moult in some. Grallina, nidification of. Grasshoppers, stridulation of the. Gratiolet, Prof., on the anthropomorphous apes; on the evolution of the anthropomorphous apes; on the difference in the development of the brains of apes and of man. Gray, Asa, on the gradation of species among the Compositae. Gray, J.E., on the caudal vertebrae of monkeys; on the presence of rudiments of horns in the female of Cervulus moschatus; on the horns of goats and sheep; on crests of male antelopes; on the beard of the ibex; on the Berbura goat; on sexual differences in the coloration of Rodents; ornaments of male sloth; on the colours of the Elands; on the Sing-sing antelope; on the colours of goats; on Lemur Macaco; on the hog-deer. "Greatest happiness principle." Greeks, ancient. Green, A.H., on beavers fighting; on the voice of the beaver. Greenfinch, selected by a female canary. Greg, W.R., on the effects of natural selection on civilised nations; on the early marriages of the poor; on the Ancient Greeks. Grenadiers, Prussian. Greyhounds, numerical proportion of the sexes in; numerical proportion of male and female births in. Grouse, red, monogamous; pugnacity of young male; producing a sound by beating their wings together; duration of courtship of; colours and nidification of. Gruber, Dr., on the occurrence of the supra-condyloid foramen in the humerus of man; on division of malar bone; stridulation of locust; on ephippiger. Grus americanus, age of mature plumage in; breeding in immature plumage. Grus virgo, trachea of. Gryllus campestris, pugnacity of male. Gryllus domesticus. Grypus, sexual differences in the beak in. Guanacoes, battles of; canine teeth of. Guanas, strife for women among the; polyandry among the. Guanche skeletons, occurrence of the supra-condyloid foramen in the humerus of. Guaranys, proportion of men and women among; colour of new-born children of the; beards of the. Guenee, A., on the sexes of Hyperythra. Guilding, L., on the stridulation of the Locustidae. Guillemot, variety of the. Guinea, sheep of, with males only horned. Guinea-fowl, monogamous; occasional polygamy of the; markings of the. Guinea-pigs, inheritance of the effects of operations by. Gulls, seasonal change of plumage in; white. Gunther, Dr., on paddle of Ceradotus; on hermaphroditism in Serranus; on male fishes hatching ova in their mouths; on mistaking infertile female fishes for males; on the prehensile organs of male Plagiostomous fishes; spines and brushes on fishes; on the pugnacity of the male salmon and trout; on the relative size of the sexes in fishes; on sexual differences in fishes; on the genus Callionymus; on a protective resemblance of a pipe-fish; on the genus Solenostoma; on the coloration of frogs and toads; combat of Testudo elegans; on the sexual differences in the Ophidia; on differences of the sexes of lizards. Gynanisa Isis, ocellated spots of. Gypsies, uniformity of, in various parts of the world. Habits, bad, facilitated by familiarity; variability of the force of. Haeckel, E., on the origin of man; on rudimentary characters; on death caused by inflammation of the vermiform appendage; on the canine teeth in man; on the steps by which man became a biped; on man as a member of the Catarrhine group; on the position of the Lemuridae; on the genealogy of the Mammalia; on the lancelet; on the transparency of pelagic animals; on the musical powers of women. Hagen, H., and Walsh, B.D., on American Neuroptera. Hair, development of, in man; character of, supposed to be determined by light and heat; distribution of, in man; possibly removed for ornamental purposes; arrangement and direction of; of the early progenitors of man; different texture of, in distinct races; and skin, correlation of colour of; development of, in mammals; management of, among different peoples; great length of, in some North American tribes; elongation of the, on the human head; possible inherited effect of plucking out. Hairiness, difference of, in the sexes in man; variation of, in races of men. Hairs and excretory pores, numerical relation of, in sheep. Hairy family, Siamese. Halbertsma, Prof., hermaphroditism in Serranus. Hamadryas baboon, turning over stones; mane of the male. Hamilton, C., on the cruelty of the Kaffirs to animals; on the engrossment of the women by the Kaffir chiefs. Hammering, difficulty of. Hancock, A., on the colours of the nudibranch Mollusca. Hands, larger at birth, in the children of labourers; structure of, in the quadrumana; and arms, freedom of, indirectly correlated with diminution of canines. Handwriting, inherited. Handyside, Dr., supernumerary mammae in men. Harcourt, E. Vernon, on Fringilla cannabina. Hare, protective colouring of the. Harelda glacialis. Hares, battles of male. Harlan, Dr., on the difference between field-and house-slaves. Harris, J.M., on the relation of complexion to climate. Harris, T.W., on the Katy-did locust; on the stridulation of the grasshoppers; on Oecanthus nivalis; on the colouring of Lepidoptera; on the colouring of Saturnia Io. Harting, spur of the Ornithorhynchus. Hartman, Dr., on the singing of Cicada septendecim. Hatred, persistence of. Haughton, S., on a variation of the flexor pollicis longus in man. Hawks, feeding orphan nestling. Hayes, Dr., on the diverging of sledge-dogs on thin ice. Haymond, R., on the drumming of the male Tetrao umbellus; on the drumming of birds. Head, altered position of, to suit the erect attitude of man; hairiness of, in man; processes of, in male beetles; artificial alterations of the form of the. Hearne, on strife for women among the North American Indians; on the North American Indians' notion of female beauty; repeated elopements of a North American woman. Heart, in the human embryo. Heat, supposed effects of. Hectocotyle. Hedge-warbler, young of the. Heel, small projection of, in the Aymara Indians. Hegt, M., on the development of the spurs in peacocks. Heliconidae, mimicry of, by other butterflies. Heliopathes, stridulation peculiar to the male. Heliothrix auriculata, young of. Helix pomatia, example of individual attachment in. Hellins, J., proportions of sexes of Lepidoptera reared by. Helmholtz, on pleasure derived from harmonies; on the human eye; on the vibration of the auditory hairs of crustacea; the physiology of harmony. Hemiptera. Hemitragus, beardless in both sexes. Hemsbach, M. von, on medial mamma in man. Hen, clucking of. Hepburn, Mr., on the autumn song of the water-ouzel. Hepialus humuli, sexual difference of colour in the. Herbs, poisonous, avoided by animals. Hermaphroditism, of embryos; in fishes. Herodias bubulcus, vernal moult of. Heron, Sir R., on the habits of peafowl. Herons, love-gestures of; decomposed feathers in; breeding plumage of; young of the; sometimes dimorphic; continued growth of crest and plumes in the males of some; change of colour in some. Hesperomys cognatus. Hetaerina, proportion of the sexes in; difference in the sexes of. Heterocerus, stridulation of. Hewitt, Mr., on a game-cock killing a kite; on the recognition of dogs and cats by ducks; on the pairing of a wild duck with a pintail drake; on the courtship of fowls; on the coupling of pheasants with common hens. Hilgendorf, sounds produced by crustaceans. Hindoo, his horror of breaking his caste. Hindoos, local difference of stature among; difference of, from Europeans; colour of the beard in. Hipparchia Janira, instability of the ocellated spots of. Hippocampus, development of; marsupial receptacles of the male. Hippocampus minor. Hippopotamus, nakedness of. Hips, proportions of, in soldiers and sailors. Hodgson, S., on the sense of duty. Hoffberg, on the horns of the reindeer; on sexual preferences shewn by reindeer. Hoffman, Prof., protective colours; fighting of frogs. Hog, wart-; river-. Hog-deer. Holland, Sir H., on the effects of new diseases. Homologous structures, correlated variation of. Homoptera, stridulation of the, and Orthoptera, discussed. Honduras, Quiscalus major in. Honey-buzzard of India, variation in the crest of. Honey-sucker, females and young of. Honey-suckers, moulting of the; Australian, nidification of. Honour, law of. Hooker, Dr., forbearance of elephant to his keeper; on the colour of the beard in man. Hookham, Mr., on mental concepts in animals. Hoolock Gibbon, nose of. Hoopoe, sounds produced by male. Hoplopterus armatus, wing-spurs of. Hornbill, African, inflation of the neck-wattle of the male during courtship. Hornbills, sexual difference in the colour of the eyes in; nidification and incubation of. Horne, C., on the rejection of a brightly-coloured locust by lizards and birds. Horns, sexual differences of, in sheep and goats; loss of, in female merino sheep; development of, in deer; development in antelopes; from the head and thorax, in male beetles; of deer; originally a masculine character in sheep; and canine teeth, inverse development of. Horse, fossil, extinction of the, in South America; polygamous; canine teeth of male; winter change of colour. Horses, rapid increase of, in South America; diminution of canine teeth in; dreaming; of the Falkland Islands and Pampas; numerical proportion of the sexes, in; lighter in winter in Siberia; sexual preferences in; pairing preferently with those of the same colour; numerical proportion of male and female births in; formerly striped. Hottentot women, peculiarities of. Hottentots, lice of; readily become musicians; notions of female beauty of the; compression of nose by. Hough, Dr. S., men's temperature more variable than women's; proportion of sexes in man. House-slaves, difference of, from field-slaves. Houzeau, on the baying of the dog; on reason in dogs; birds killed by telegraph wires; on the cries of domestic fowls and parrots; animals feel no pity; suicide in the Aleutian Islands. Howorth, H.H., extinction of savages. Huber, P., on ants playing together; on memory in ants; on the intercommunication of ants; on the recognition of each other by ants after separation. Huc, on Chinese opinions of the appearance of Europeans. Huia, the, of New Zealand. Human, man, classed alone in a kingdom. Human sacrifices. Humanity, unknown among some savages; deficiency of, among savages. Humboldt, A. von, on the rationality of mules; on a parrot preserving the language of a lost tribe; on the cosmetic arts of savages; on the exaggeration of natural characters by man; on the red painting of American Indians. Hume, D., on sympathetic feelings. Humming-bird, racket-shaped feathers in the tail of a; display of plumage by the male. Humming-birds, ornament their nests; polygamous; proportion of the sexes in; sexual differences in; pugnacity of male; modified primaries of male; coloration of the sexes of; display by; nidification of the; colours of female; young of. Humour, sense of, in dogs. Humphreys, H.N., on the habits of the stickleback. Hunger, instinct of. Huns, ancient, flattening of the nose by the. Hunter, J., on the number of species of man; on secondary sexual characters; on the general behaviour of female animals during courtship; on the muscles of the larynx in song-birds; on strength of males; on the curled frontal hair of the bull; on the rejection of an ass by a female zebra. Hunter, W.W., on the recent rapid increase of the Santali; on the Santali. Huss, Dr. Max, on mammary glands. Hussey, Mr., on a partridge distinguishing persons. Hutchinson, Col., example of reasoning in a retriever. Hutton, Captain, on the male wild goat falling on his horns. Huxley, T.H., on the structural agreement of man with the apes; on the agreement of the brain in man with that of lower animals; on the adult age of the orang; on the embryonic development of man; on the origin of man; on variation in the skulls of the natives of Australia; on the abductor of the fifth metatarsal in apes; on the nature of the reasoning power; on the position of man; on the suborders of primates; on the Lemuridae; on the Dinosauria; on the amphibian affinities of the Ichthyosaurians; on variability of the skull in certain races of man; on the races of man; Supplement on the brain. Hybrid birds, production of. Hydrophobia, communicable between man and the lower animals. Hydroporus, dimorphism of females of. Hyelaphus porcinus. Hygrogonus. Hyla, singing species of. Hylobates, absence of the thumb in; upright progression of some species of; maternal affection in a; direction of the hair on the arms of species of; females of, less hairy below than males. Hylobates agilis, hair on the arms of; musical voice of the; superciliary ridge of; voice of. Hylobates hoolock, sexual difference of colour in. Hylobates lar, hair on the arms of; female less hairy. Hylobates leuciscus, song of. Hylobates syndactylus, laryngeal sac of. Hylophila prasinana. Hymenoptera, large size of the cerebral ganglia in; classification of; sexual differences in the wings of; aculeate, relative size of the sexes of. Hymenopteron, parasitic, with a sedentary male. Hyomoschus aquaticus. Hyperythra, proportion of the sexes in. Hypogymna dispar, sexual difference of colour in. Hypopyra, coloration of. Ibex, male, falling on his horns; beard of the. Ibis, white, change of colour of naked skin in, during the breeding season; scarlet, young of the. Ibis tantalus, age of mature plumage in; breeding in immature plumage. Ibises, decomposed feathers in; white; and black. Ichneumonidae, difference of the sexes in. Ichthyopterygia. Ichthyosaurians. Idiots, microcephalous, their characters and habits; hairiness and animal nature of their actions; microcephalous, imitative faculties of. Iguana tuberculata. Iguanas. Illegitimate and legitimate children, proportion of the sexes in. Imagination, existence of, in animals. Imitation, of man by monkeys; tendency to, in monkeys, microcephalous idiots and savages; influence of. Immature plumage of birds. Implacentata. Implements, employed by monkeys; fashioning of, peculiar to man. Impregnation, period of, influence of, upon sex. Improvement, progressive, man alone supposed to be capable of. Incisor teeth, knocked out or filed by some savages. Increase, rate of; necessity of checks in. Indecency, hatred of, a modern virtue. India, difficulty of distinguishing the native races of; Cyprinidae of; colour of the beard in races of men of. Indian, North American, honoured for scalping a man of another tribe. Individuality, in animals. Indolence of man, when free from a struggle for existence. Indopicus carlotta, colours of the sexes of. Infanticide, prevalence of; supposed cause of; prevalence and causes of. Inferiority, supposed physical, of man. Inflammation of the bowels, occurrence of, in Cebus Azarae. Inheritance, of long and short sight; of effects of use of vocal and mental organs; of moral tendencies; laws of; sexual; sexually limited. Inquisition, influence of the. Insanity, hereditary. insect, fossil, from the Devonian. Insectivora, absence of secondary sexual characters in. Insects, relative size of the cerebral ganglia in; male, appearance of, before the females; pursuit of female, by the males; period of development of sexual characters in; secondary sexual characters of; kept in cages; stridulation. Insessores, vocal organs of. Instep, depth of, in soldiers and sailors. Instinct and intelligence. Instinct, migratory, vanquishing the maternal. Instinctive actions, the result of inheritance. Instinctive impulses, difference of the force; and moral impulses, alliance of. Instincts, complex origin of, through natural selection; possible origin of some; acquired, of domestic animals; variability of the force of; difference of force between the social and other; utilised for new purposes. Instrumental music of birds. Intellect, influence of, in natural selection in civilised society. Intellectual faculties, their influence on natural selection in man; probably perfected through natural selection. Intelligence, Mr. H. Spencer on the dawn of. Intemperance, no reproach among savages; its destructiveness. Intoxication in monkeys. Iphias glaucippe. Iris, sexual difference in the colour of the, in birds. Ischio-pubic muscle. Ithaginis cruentus, number of spurs in. Iulus, tarsal suckers of the males of. Jackals learning from dogs to bark. Jack-snipe, coloration of the. Jacquinot, on the number of species of man. Jaeger, Dr., length of bones increased from carrying weights; on the difficulty of approaching herds of wild animals; male Silver-pheasant, rejected when his plumage was spoilt. Jaguars, black. Janson, E.W., on the proportions of the sexes in Tomicus villosus; on stridulant beetles. Japan, encouragement of licentiousness in. Japanese, general beardlessness of the; aversion of the, to whiskers. Jardine, Sir W., on the Argus pheasant. Jarrold, Dr., on modifications of the skull induced by unnatural position. Jarves, Mr., on infanticide in the Sandwich Islands. Javans, relative height of the sexes of; notions of female beauty. Jaw, influence of the muscles of the, upon the physiognomy of the apes. Jaws, smaller proportionately to the extremities; influence of food upon the size of; diminution of, in man; in man, reduced by correlation. Jay, young of the; Canada, young of the. Jays, new mates found by; distinguishing persons. Jeffreys, J. Gwyn, on the form of the shell in the sexes of the Gasteropoda; on the influence of light upon the colours of shells. Jelly-fish, bright colours of some. Jenner, Dr., on the voice of the rook; on the finding of new mates by magpies; on retardation of the generative functions in birds. Jenyns, L., on the desertion of their young by swallows; on male birds singing after the proper season. Jerdon, Dr., on birds dreaming; on the pugnacity of the male bulbul; on the pugnacity of the male Ortygornis gularis; on the spurs of Galloperdix; on the habits of Lobivanellus; on the spoonbill; on the drumming of the Kalij-pheasant; on Indian bustards; on Otis bengalensis; on the ear-tufts of Sypheotides auritus; on the double moults of certain birds; on the moulting of the honeysuckers; on the moulting of bustards, plovers, and drongos; on the spring change of colour in some finches; on display in male birds; on the display of the under-tail coverts by the male bulbul; on the Indian honey-buzzard; on sexual differences in the colour of the eyes of hornbills; on the markings of the Tragopan pheasant; on the nidification of the Orioles; on the nidification of the hornbills; on the Sultan yellow-tit; on Palaeornis javanicus; on the immature plumage of birds; on representative species of birds; on the habits of Turnix; on the continued increase of beauty of the peacock; on coloration in the genus Palaeornis. Jevons, W.S., on the migrations of man. Jews, ancient use of flint tools by the; uniformity of, in various parts of the world; numerical proportion of male and female births among the; ancient, tattooing practised by. Johnstone, Lieut., on the Indian elephant. Jollofs, fine appearance of the. Jones, Albert, proportion of sexes of Lepidoptera, reared by. Juan Fernandez, humming-birds of. Junonia, sexual differences of colouring in species of. Jupiter, comparison with Assyrian effigies. Kaffir skull, occurrence of the diastema in a. Kaffirs, their cruelty to animals; lice of the; colour of the; engrossment of the handsomest women by the chiefs of the; marriage-customs of the. Kalij-pheasant, drumming of the male; young of. Kallima, resemblance of, to a withered leaf. Kulmucks, general beardlessness of; aversion of, to hairs on the face; marriage-customs of the. Kangaroo, great red, sexual difference in the colour of. Kant, Imm., on duty; on self-restraint; on the number of species of man. Katy-did, stridulation of the. Keen, Dr., on the mental powers of snakes. Keller, Dr., on the difficulty of fashioning stone implements. Kent, W.S., elongation of dorsal fin of Callionymus lyra; courtship of Labrus mixtus; colours and courtship of Cantharus lineatus. Kestrels, new mates found by. Kidney, one, doing double work in disease. King, W.R., on the vocal organs of Tetrao cupido; on the drumming of grouse; on the reindeer; on the attraction of male deer by the voice of the female. King and Fitzroy, on the marriage-customs of the Fuegians. King-crows, nidification of. Kingfisher, racket-shaped feathers in the tail of a. Kingfishers, colours and nidification of the; immature plumage of the; young of the. King Lory, immature plumage of the. Kingsley, C., on the sounds produced by the Umbrina. Kirby and Spence, on sexual differences in the length of the snout in Curculionidae; on the courtship of insects; on the elytra of Dytiscus; on peculiarities in the legs of male insects; on the relative size of the sexes in insects; on the Fulgoridae; on the habits of the Termites; on difference of colour in the sexes of beetles; on the horns of the male lamellicorn beetles; on hornlike processes in male Curculionidae; on the pugnacity of the male stag-beetle. Kite, killed by a game-cock. Knot, retention of winter plumage by the. Knox, R., on the semilunar fold; on the occurrence of the supra-condyloid foramen in the humerus of man; on the features of the young Memmon. Koala, length of the caecum in. Kobus ellipsiprymnus, proportion of the sexes in. Kolreuter, on the sterility of hybrid plants. Koodoo, development of the horns of the; markings of the. Koppen, F.T., on the migratory locust. Koraks, marriage customs of. Kordofan, protuberances artificially produced by natives of. Korte, on the proportion of sexes in locusts; Russian locusts. Kovalevsky, A., on the affinity of the Ascidia to the Vertebrata. Kovalevsky, W., on the pugnacity of the male capercailzie; on the pairing of the capercailzie. Krause, on a convoluted body at the extremity of the tail in a Macacus and a cat. Kupffer, Prof., on the affinity of the Ascidia to the Vertebrata. Labidocera Darwinii, prehensile organs of the male. Labrus, splendid colours of the species of. Labrus mixtus, sexual differences in. Labrus pavo. Lacertilia, sexual differences of. Lafresnaye, M. de, on birds of paradise. Lamarck, on the origin of man. Lamellibranchiata. Lamellicorn beetles, horn-like processes from the head and thorax of; influence of sexual selection on. Lamellicornia, stridulation of. Lamont, Mr., on the tusks of the walrus; on the use of its tusks by the walrus; on the bladder-nose seal. Lampornis porphyrurus, colours of the female. Lampyridae, distasteful to mammals. Lancelet. Landois, H., gnats attracted by sound; on the production of sound by the Cicadae; on the stridulating organ of the crickets; on Decticus; on the stridulating organs of the Acridiidae; stridulating apparatus, in Orthoptera; on the stridulation of Necrophorus; on the stridulant organ of Cerambyx heros; on the stridulant organ of Geotrupes; on the stridulating organs in the Coleoptera; on the ticking of Anobium. Landor, Dr., on remorse for not obeying tribal custom. Language, an art; articulate, origin of; relation of the progress of, to the development of the brain; effects of inheritance in production of; complex structure of, among barbarous nations; natural selection in; gesture; primeval; of a lost tribe preserved by a parrot. Languages, presence of rudiments in; classification of; variability of; crossing or blending of; complexity of, no test of perfection or proof of special creation; resemblance of, evidence of community of origin. Languages and species, identity of evidence of their gradual development. Lanius, characters of young. Lanius rufus, anomalous young of. Lankester, E.R., on comparative longevity; on the destructive effects of intemperance. Lanugo of the human foetus. Lapponian language, highly artificial. Lark, proportion of the sexes in the; female, singing of the. Larks, attracted by a mirror. Lartet, E., comparison of cranial capacities of skulls of recent and tertiary mammals; on the size of the brain in mammals; on Dryopithecus; on pre-historic flutes. Larus, seasonal change of plumage in. Larva, luminous, of a Brazilian beetle. Larynx, muscles of the, in songbirds. Lasiocampa quercus, attraction of males by the female; sexual difference of colour in. Latham, R.G., on the migrations of man. Latooka, perforation of the lower lip by the women of. Laurillard, on the abnormal division of the malar bone in man. Lawrence, W., on the superiority of savages to Europeans in power of sight; on the colour of negro infants; on the fondness of savages for ornaments; on beardless races; on the beauty of the English aristocracy. Layard, E.L., on the instance of rationality in a cobra; on the pugnacity of Gallus Stanleyi. Laycock, Dr., on vital periodicity; theroid nature of idiots. Leaves, autumn, tints useless. Lecky, Mr., on the sense of duty; on suicide; on the practice of celibacy; his view of the crimes of savages; on the gradual rise of morality. Leconte, J.L., on the stridulant organ in the Coprini and Dynastini. Lee, H., on the numerical proportion of the sexes in the trout. Leg, calf of the, artificially modified. Legitimate and illegitimate children, proportion of the sexes in. Legs, variation of the length of the, in man; proportions of, in soldiers and sailors; front, atrophied in some male butterflies; peculiarities of, in male insects. Leguay, on the occurrence of the supra-condyloid foramen in the humerus of man. Lek of the black-cock and capercailzie. Lemoine, Albert, on the origin of language. Lemur macaco, sexual difference of colour in. Lemuridae, ears of the; variability of the muscles in the; position and derivation of the; their origin. Lemurs, uterus in the. Lenguas, disfigurement of the ears of the. Leopards, black. Lepidoptera, numerical proportions of the sexes in the; colouring of; ocellated spots of. Lepidosiren. Leptalides, mimicry of. Leptorhynchus angustatus, pugnacity of male. Leptura testacea, difference of colour in the sexes. Leroy, on the wariness of young foxes in hunting-districts; on the desertion of their young by swallows. Leslie, D., marriage customs of Kaffirs. Lesse, valley of the. Lesson, on the birds of paradise; on the sea-elephant. Lessona, M., observations on Serranus. Lethrus cephalotes, pugnacity of the males of. Leuciscus phoxinus. Leuckart, R., on the vesicula prostatica; on the influence of the age of parents on the sex of offspring. Levator claviculae muscle. Libellula depressa, colour of the male. Libellulidae, relative size of the sexes of; difference in the sexes of. Lice of domestic animals and man. Licentiousness a check upon population; prevalence of, among savages. Lichtenstein, on Chera progne. Life, inheritance at corresponding periods of. Light, effects on complexion; influence of, upon the colours of shells. Lilford, Lord, the ruff attracted by bright objects. Limosa lapponica. Linaria. Linaria montana. Lindsay, Dr. W.L., diseases communicated from animals to man; madness in animals; the dog considers his master his God. Linnaeus, views of, as to the position of man. Linnet, numerical proportion of the sexes in the; crimson forehead and breast of the; courtship of the. Lion, polygamous; mane of the, defensive; roaring of the. Lions, stripes of young. Lips, piercing of the, by savages. Lithobius, prehensile appendages of the female. Lithosia, coloration in. Littorina littorea. Livingstone, Dr., manner of sitting of gorilla; on the influence of dampness and dryness on the colour of the skin; on the liability of negroes to tropical fevers after residence in a cold climate; on the spur-winged goose; on weaverbirds; on an African night-jar; on the battle-scars of South African male mammals; on the removal of the upper incisors by the Batokas; on the perforation of the upper lip by the Makalolo; on the Banyai. Livonia, numerical proportion of male and female births in. Lizards, relative size of the sexes of; gular pouches of. Lloyd, L., on the polygamy of the capercailzie and bustard; on the numerical proportion of the sexes in the capercailzie and blackcock; on the salmon; on the colours of the sea-scorpion; on the pugnacity of male grouse; on the capercailzie and blackcock; on the call of the capercailzie; on assemblages of grouse and snipes; on the pairing of a shield-drake with a common duck; on the battles of seals; on the elk. Lobivanellus, wing-spurs in. Local influences, effect of, upon stature. Lockwood, Mr., on the development of Hippocampus. Lockwood, Rev. S., musical mouse. Locust, bright-coloured, rejected by lizards and birds. Locust, migratory; selection by female. Locustidae, stridulation of the; descent of the. Locusts, proportion of sexes in; stridulation of. Longicorn beetles, difference of the sexes of, in colour; stridulation of. Lonsdale, Mr., on an example of personal attachment in Helix pomatia. Lophobranchii, marsupial receptacles of the male. Lophophorus, habits of. Lophorina atra, sexual difference in coloration of. Lophornis ornatus. Lord, J.K., on Salmo lycaodon. Lory, King; immature plumage of the. Lory, King, constancy of. Love-antics and dances of birds. Lowne, B.T., on Musca vomitoria. Loxia, characters of young of. Lubbock, Sir J., on the antiquity of man; on the origin of man; on the mental capacity of savages; on the origin of implements; on the simplification of languages; on the absence of the idea of God among certain races of men; on the origin of the belief in spiritual agencies; on superstitions; on the sense of duty; on the practice of burying the old and sick among the Fijians; on the immorality of savages; on Mr. Wallace's claim to the origination of the idea of natural selection; on the former barbarism of civilised nations; on improvements in the arts among savages; on resemblances of the mental characters in different races of men; on the arts practised by savages; on the power of counting in primeval man; on the prehensile organs of the male Labidocera Darwinii; on Chloeon; on Smynthurus luteus; finding of new mates by jays; on strife for women among the North American Indians; on music; on the ornamental practices of savages; on the estimation of the beard among the Anglo-Saxons; on artificial deformation of the skull; on "communal marriages;" on exogamy; on the Veddahs; on polyandry. Lucanidae, variability of the mandibles in the male. Lucanus, large size of males of. Lucanus cervus, numerical proportion of sexes of; weapons of the male. Lucanus elaphus, use of mandibles of; large jaws of male. Lucas, Prosper, on pigeons; on sexual preference in horses and bulls. Luminosity in insects. Lunar periods. Lund, Dr., on skulls found in Brazilian caves. Lungs, enlargement of, in the Quichua and Aymara Indians; a modified swim-bladder; different capacity of, in races of man. Luschka, Prof., on the termination of the coccyx. Luxury, expectation of life uninfluenced by. Lycaena, sexual differences of colour in species of. Lycaenae, colours of. Lyell, Sir C., on the antiquity of man; on the origin of man; on the parallelism of the development of species and languages; on the extinction of languages; on the Inquisition; on the fossil remains of vertebrata; on the fertility of mulattoes. Lynx, Canadian throat-ruff of the. Lyre-bird, assemblies of. Macacus, ears of; convoluted body in the extremity of the tail of; variability of the tail in species of; whiskers of species of. Macacus brunneus. Macacus cynomolgus, superciliary ridge of; beard and whiskers of; becoming white with age. Macacus ecaudatus. Macacus lasiotus, facial spots of. Macacus nemestrinus. Macacus radiatus. Macacus rhesus, sexual difference in the colour of. Macalister, Prof., on variations of the palmaris accessorius muscle; on muscular abnormalities in man; on the greater variability of the muscles in men than in women. Macaws, Mr. Buxton's observations on. McCann, J., on mental individuality. McClelland, J., on the Indian Cyprinidae. Macculloch, Col., on an Indian village without any female children. Macculloch, Dr., on tertian ague in a dog. Macgillivray, W., on the vocal organs of birds; on the Egyptian goose; on the habits of woodpeckers; on the habits of the snipe; on the whitethroat; on the moulting of the snipes; on the moulting of the Anatidae; on the finding of new mates by magpies; on the pairing of a blackbird and thrush; on pied ravens; on the guillemots; on the colours of the tits; on the immature plumage of birds. Machetes, sexes and young of. Machetes pugnax, supposed to be polygamous; numerical proportion of the sexes in; pugnacity of the male; double moult in. McIntosh, Dr., colours of the Nemertians. McKennan, marriage customs of Koraks. Mackintosh, on the moral sense. MacLachlan, R., on Apatania muliebris and Boreus hyemalis; on the anal appendages of male insects; on the pairing of dragon-flies; on dragon-flies; on dimorphism in Agrion; on the want of pugnacity in male dragon-flies; colour of ghost-moth in the Shetland Islands. M'Lennan, Mr., on infanticide; on the origin of the belief in spiritual agencies; on the prevalence of licentiousness among savages; on the primitive barbarism of civilised nations; on traces of the custom of the forcible capture of wives; on polyandry. Macnamara, Mr., susceptibility of Andaman islanders and Nepalese to change. M'Neill, Mr., on the use of the antlers of deer; on the Scotch deerhound; on the long hairs on the throat of the stag; on the bellowing of stags. Macropus, courtship of. Macrorhinus proboscideus, structure of the nose of. Magpie, power of speech of; vocal organs of the; nuptial assemblies of; new mates found by; stealing bright objects; young of the; coloration of the. Maillard, M., on the proportion of the sexes in a species of Papilio from Bourbon. Maine, Sir Henry, on the absorption of one tribe by another; a desire for improvement not general. Major, Dr. C. Forsyth, on fossil Italian apes; skull of Bos etruscus; tusks of miocene pigs. Makalolo, perforation of the upper lip by the. Malar bone, abnormal division of, in man. Malay Archipelago, marriage-customs of the savages of the. Malays, line of separation between the Papuans and the; general beardlessness of the; staining of the teeth among; aversion of some, to hairs on the face. Malays and Papuans, contrasted characters of. Male animals, struggles of, for the possession of the females; eagerness of, in courtship; generally more modified than female; differ in the same way from females and young. Male characters, developed in females; transfer of, to female birds. Male, sedentary, of a hymenopterous parasite. Malefactors. Males, presence of rudimentary female organs in. Males and females, comparative numbers of; comparative mortality of, while young. Malherbe, on the woodpeckers. Mallotus Peronii. Mallotus villosus. Malthus, T., on the rate of increase of population. Maluridae, nidification of the. Malurus, young of. Mammae, rudimentary, in male mammals; supernumerary, in women; of male human subject. Mammalia, Prof. Owen's classification of; genealogy of the. Mammals, recent and tertiary, comparison of cranial capacity of; nipples of; pursuit of female, by the males; secondary sexual characters of; weapons of; relative size of the sexes of; parallelism of, with birds in secondary sexual characters; voices of, used especially during the breeding season. Man, variability of; erroneously regarded as more domesticated than other animals; migrations of; wide distribution of; causes of the nakedness of; supposed physical inferiority of; a member of the Catarrhine group; early progenitors of; transition from ape indefinite; numerical proportions of the sexes in; difference between the sexes; proportion of sexes amongst the illegitimate; different complexion of male and female negroes; secondary sexual characters of; primeval condition of. Mandans, correlation of colour and texture of hair in the. Mandible, left, enlarged in the male of Taphroderes distortus. Mandibles, use of the, in Ammophila; large, of Corydalis cornutus; large, of male Lucanus elaphus. Mandrill, number of caudal vertebrae in the; colours of the male. Mantegazza, Prof., on last molar teeth of man; bright colours in male animals; on the ornaments of savages; on the beardlessness of the New Zealanders; on the exaggeration of natural characters by man. Mantell, W., on the engrossment of pretty girls by the New Zealand chiefs. Mantis, pugnacity of species of. Maories, mortality of; infanticide and proportion of sexes; distaste for hairiness amongst men. Marcus Aurelius, on the origin of the moral sense; on the influence of habitual thoughts. Mareca penelope. Marks, retained throughout groups of birds. Marriage, restraints upon, among savages; influence of, upon morals; influence of, on mortality; development of. Marriages, early; communal. Marshall, Dr. W., protuberances on birds' heads; on the moulting of birds; advantage to older birds of paradise. Marshall, Col., interbreeding amongst Todas; infanticide and proportion of sexes with Todas; choice of husband amongst Todas. Marshall, Mr., on the brain of a Bushwoman. Marsupials, development of the nictitating membrane in; uterus of; possession of nipples by; their origin from Monotremata; abdominal sacs of; relative size of the sexes of; colours of. Marsupium, rudimentary in male marsupials. Martin, W.C.L., on alarm manifested by an orang at the sight of a turtle; on the hair in Hylobates; on a female American deer; on the voice of Hylobates agilis; on Semnopithecus nemaeus. Martin, on the beards of the inhabitants of St. Kilda. Martins deserting their young. Martins, C., on death caused by inflammation of the vermiform appendage. Mastoid processes in man and apes. Maudsley, Dr., on the influence of the sense of smell in man; on idiots smelling their food; on Laura Bridgman; on the development of the vocal organs; moral sense failing in incipient madness; change of mental faculties at puberty in man. Mayers, W.F., on the domestication of the goldfish in China. Mayhew, E., on the affection between individuals of different sexes in the dog. Maynard, C.J., on the sexes of Chrysemys picta. Meckel, on correlated variation of the muscles of the arm and leg. Medicines, effect produced by, the same in man and in monkeys. Medusae, bright colours of some. Megalithic structures, prevalence of. Megapicus validus, sexual difference of colour in. Megasoma, large size of males of. Meigs, Dr. A., on variation in the skulls of the natives of America. Meinecke, on the numerical proportion of the sexes in butterflies. Melanesians, decrease of. Meldola, Mr., colours and marriage flight of Colias and Pieris. Meliphagidae, Australian, nidification of. Melita, secondary sexual characters of. Meloe, difference of colour in the sexes of a species of. Memnon, young. Memory, manifestations of, in animals. Mental characters, difference of, in different races of men. Mental faculties, diversity of, in the same race of men; inheritance of; variation of, in the same species; similarity of the, in different races of man; of birds. Mental powers, difference of, in the two sexes in man. Menura Alberti, song of. Menura superba, long tails of both sexes of. Merganser, trachea of the male. Merganser serrator, male plumage of. Mergus cucullatus, speculum of. Mergus merganser, young of. Metallura, splendid tail-feathers of. Methoca ichneumonides, large male of. Meves, M., on the drumming of the snipe. Mexicans, civilisation of the, not foreign. Meyer, on a convoluted body at the extremity of the tail in a Macacus and a cat. Meyer, Dr. A., on the copulation of Phryganidae of distinct species. Meyer, Prof. L., on development of helix of ear; men's ears more variable than women's; antennae serving as ears. Migrations of man, effects of. Migratory instinct of birds; vanquishing the maternal. Mill, J.S., on the origin of the moral sense; on the "greatest happiness principle;" on the difference of the mental powers in the sexes of man. Millipedes. Milne-Edwards, H., on the use of enlarged chelae of the male Gelasimus. Milvago leucurus, sexes and young of. Mimicry. Mimus polyglottus. Mind, difference of, in man and the highest animals; similarity of the, in different races. Minnow, proportion of the sexes in the. Mirror, behaviour of monkeys before. Mirrors, larks attracted by. Mitchell, Dr., interbreeding in the Hebrides. Mitford, selection of children in Sparta. Mivart, St. George, on the reduction of organs; on the ears of the lemuroidea; on variability of the muscles in lemuroidea; on the caudal vertebrae of monkeys; on the classification of the primates; on the orang and on man; on differences in the lemuroidea; on the crest of the male newt. Mobius, Prof., on reasoning powers in a pike. Mocking-thrush, partial migration of; young of the. Modifications, unserviceable. Moggridge, J.T., on habits of spiders; on habits of ants. Moles, numerical proportion of the sexes in; battles of male. Mollienesia petenensis, sexual difference in. Mollusca, beautiful colours and shapes of; absence of secondary sexual characters in the. Molluscoida. Monacanthus scopas and M. Peronii. Monboddo, Lord, on music. Mongolians, perfection of the senses in. Monkey, protecting his keeper from a baboon; bonnet-; rhesus-, sexual difference in colour of the; moustache-, colours of the. Monkeys, liability of, to the same diseases as man; male, recognition of women by; diversity of the mental faculties in; breaking hard fruits with stones; hands of the; basal caudal vertebrae of, imbedded in the body; revenge taken by; maternal affection in; variability of the faculty of attention in; American, manifestation of reason in; using stones and sticks; imitative faculties of; signal-cries of; mutual kindnesses of; sentinels posted by; human characters of; American, direction of the hair on the arms of some; gradation of species of; beards of; ornamental characters of; analogy of sexual differences of, with those of man; different degrees of difference in the sexes of; expression of emotions by; generally monogamous habits of; polygamous habits of some; naked surfaces of; courtship of. Monogamy, not primitive. Monogenists. Mononychus pseudacori, stridulation of. Monotremata, development of the nictitating membrane in; lactiferous glands of; connecting mammals with reptiles. Monstrosities, analogous, in man and lower animals; caused by arrest of development; correlation of; transmission of. Montagu, G., on the habits of the black and red grouse; on the pugnacity of the ruff; on the singing of birds; on the double moult of the male pintail. Monteiro, Mr., on Bucorax abyssinicus. Montes de Oca, M., on the pugnacity of male Humming-birds. Monticola cyanea. Monuments, as traces of extinct tribes. Moose, battles of; horns of the, an incumbrance. Moral and instinctive impulses, alliance of. Moral faculties, their influence on natural selection in man. Moral rules, distinction between the higher and lower. Moral sense, so-called, derived from the social instincts; origin of the. Moral tendencies, inheritance of. Morality, supposed to be founded in selfishness; test of, the general welfare of the community; gradual rise of; influence of a high standard of. Morgan, L.H., on the beaver; on the reasoning powers of the beaver; on the forcible capture of wives; on the castoreum of the beaver; marriage unknown in primeval times; on polyandry. Morley, J., on the appreciation of praise and fear of blame. Morris, F.O., on hawks feeding an orphan nestling. Morse, Dr., colours of mollusca. Morselli, E., division of the malar bone. Mortality, comparative, of female and male. Morton on the number of species of man. Moschkau, Dr. A., on a speaking starling. Moschus moschiferus, odoriferous organs of. Motacillae, Indian, young of. Moth, odoriferous. Moths, absence of mouth in some males; apterous female; male, prehensile use of the tarsi by; male, attracted by females; sound produced by; coloration of; sexual differences of colour in. Motmot, inheritance of mutilation of tail feathers; racket-shaped feathers in the tail of a. Moult, double; double annual, in birds. Moulting of birds. Moults, partial. Mouse, song of. Moustache-monkey, colours of the. Moustaches, in monkeys. Mud-turtle, long claws of the male. Mulattoes, persistent fertility of; immunity of, from yellow fever. Mule, sterility and strong vitality of the. Mules, rational. Muller, Ferd., on the Mexicans and Peruvians. Muller, Fritz, on astomatous males of Tanais; on the disappearance of spots and stripes in adult mammals; on the proportions of the sexes in some Crustacea; on secondary sexual characters in various Crustaceans; musical contest between male Cicadae; mode of holding wings in Castina; on birds shewing a preference for certain colours; on the sexual maturity of young amphipod Crustacea. Muller, Hermann, emergence of bees, from pupa; pollen-gathering of bees; proportion of sexes in bees; courting of Eristalis; colour and sexual selection with bees. Muller, J., on the nictitating membrane and semilunar fold. Muller, Max, on the origin of language; language implies power of general conception; struggle for life among the words, etc., of languages. Muller, S., on the banteng; on the colours of Semnopithecus chrysomelas. Muntjac-deer, weapons of the. Murie, J., on the reduction of organs; on the ears of the Lemuroidea; on variability of the muscles in the Lemuroidea; basal caudal vertebrae of Macacus brunneus imbedded in the body; on the manner of sitting in short-tailed apes; on differences in the Lemuroidea; on the throat-pouch of the male bustard; on the mane of Otaria jubata; on the sub-orbital pits of Ruminants; on the colours of the sexes in Otaria nigrescens. Murray, A., on the Pediculi of different races of men. Murray, T.A., on the fertility of Australian women with white men. Mus coninga. Mus minutus, sexual difference in the colour of. Musca vomitoria. Muscicapa grisola. Muscicapa luctuosa. Muscicapa ruticilla, breeding in immature plumage. Muscle, ischio-pubic. Muscles, rudimentary, occurrence of, in man; variability of the; effects of use and disuse upon; animal-like abnormalities of, in man; correlated variation of, in the arm and leg; variability of, in the hands and feet; of the jaws, influence of, on the physiognomy of the Apes; habitual spasms of, causing modifications of the facial bones, of the early progenitors of man; greater variability of the, in men than in women. Musculus sternalis, Prof. Turner on the. Music, of birds; discordant, love of savages for; reason of power of perception of notes in animals; power of distinguishing notes; its connection with primeval speech; different appreciation of, by different peoples; origin of; effects of. Musical cadences, perception of, by animals; powers of man. Musk-deer, canine teeth of male; male, odoriferous organs of the; winter change of the. Musk-duck, Australian; large size of male; of Guiana, pugnacity of the male. Musk-ox, horns of. Musk-rat, protective resemblance of the, to a clod of earth. Musophagae, colours and nidification of the; both sexes of, equally brilliant. Mussels opened by monkeys. Mustela, winter change of two species of. Musters, Captain, on Rhea Darwinii; marriages amongst Patagonians. Mutilations, healing of; inheritance of. Mutilla europaea, stridulation of. Mutillidae, absence of ocelli in female. Mycetes caraya, polygamous; vocal organs of; beard of; sexual differences of colour in; voice of. Mycetes seniculus, sexual differences of colour in. Myriapoda. Nageli, on the influence of natural selection on plants; on the gradation of species of plants. Nails, coloured yellow or purple in part of Africa. Narwhal, tusks of the. Nasal cavities, large size of, in American aborigines. Nascent organs. Nathusius, H. von, on the improved breeds of pigs; male domesticated animals more variable than females; horns of castrated sheep; on the breeding of domestic animals. Natural selection, its effects on the early progenitors of man; influence of, on man; limitation of the principle; influence of, on social animals; Mr. Wallace on the limitation of, by the influence of the mental faculties in man; influence of, in the progress of the United States; in relation to sex. Natural and sexual selection contrasted. Naulette, jaw from, large size of the canines in. Neanderthal skull, capacity of the. Neck, proportion of, in soldiers and sailors. Necrophorus, stridulation of. Nectarinia, young of. Nectariniae, moulting of the; nidification of. Negro, resemblance of a, to Europeans in mental characters. Negro-women, their kindness to Mungo Park. Negroes, Caucasian features in; character of; lice of; fertility of, when crossed with other races; blackness of; variability of; immunity of, from yellow fever; difference of, from Americans; disfigurements of the; colour of new-born children of; comparative beardlessness of; readily become musicians; appreciation of beauty of their women by; idea of beauty among; compression of the nose by some. Nemertians, colours of. Neolithic period. Neomorpha, sexual difference of the beak in. Nephila, size of male. Nests, made by fishes; decoration of, by Humming-birds. Neumeister, on a change of colour in pigeons after several moultings. Neuration, difference of, in the two sexes of some butterflies and hymenoptera. Neuroptera. Neurothemis, dimorphism in. New Zealand, expectation by the natives of, of their extinction; practice of tattooing in; aversion of natives of, to hairs on the face; pretty girls engrossed by the chiefs in. Newton, A., on the throat-pouch of the male bustard; on the differences between the females of two species of Oxynotus; on the habits of the Phalarope, dotterel, and godwit. Newts. Nicholson, Dr., on the non-immunity of dark Europeans from yellow fever. Nictitating membrane. Nidification of fishes; relation of, to colour; of British birds. Night-heron, cries of the. Nightingale, arrival of the male before the female; object of the song of the. Nightingales, new mates found by. Nightjar, selection of a mate by the female; Australian, sexes of; coloration of the. Nightjars, noise made by some male, with their wings; elongated feathers in. Nilghau, sexual differences of colour in the. Nilsson, Prof., on the resemblance of stone arrow-heads from various places; on the development of the horns of the reindeer. Nipples, absence of, in Monotremata. Nitsche, Dr., ear of foetal orang. Nitzsch, C.L., on the down of birds. Noctuae, brightly-coloured beneath. Noctuidae, coloration of. Nomadic habits, unfavourable to human progress. Nordmann, A., on Tetrao urogalloides. Norfolk Island, half-breeds on. Norway, numerical proportion of male and female births in. Nose, resemblance of, in man and the apes; piercing and ornamentation of the; very flat, not admired in negroes; flattening of the. Nott and Gliddon, on the features of Rameses II.; on the features of Amunoph III.; on skulls from Brazilian caves; on the immunity of negroes and mulattoes from yellow fever; on the deformation of the skull among American tribes. Novara, voyage of the, suicide in New Zealand. Nudibranch Mollusca, bright colours of. Numerals, Roman. Nunemaya, natives of, bearded. Nuthatch, of Japan, intelligence of; Indian. Obedience, value of. Observation, powers of, possessed by birds. Occupations, sometimes a cause of diminished stature; effect of, upon the proportions of the body. Ocelli, absence of, in female Mutilidae. Ocelli of birds, formation and variability of the. Ocelot, sexual differences in the colouring of the. Ocyhaps lophotes. Odonata. Odonestis potatoria, sexual difference of colour in. Odour, correlation of, with colour of skin; of moths; emitted by snakes in the breeding season; of mammals. Oecanthus nivalis, difference of colour in the sexes of. Oecanthus pellucidus. Ogle, Dr. W., relation between colour and power of smell. Oidemia. Oliver, on sounds produced by Pimelia striata. Omaloplia brunnea, stridulation of. Onitis furcifer, processes of anterior femora of the male, and on the head and thorax of the female. Onthophagus. Onthophagus rangifer, sexual differences of; variations in the horns of the male. Ophidia, sexual differences of. Ophidium. Opossum, wide range of, in America. Optic nerve, atrophy of the, caused by destruction of the eye. Orang-Outan, Bischoff on the agreement of the brain of the, with that of man; adult age of the; ears of the; vermiform appendage of; hands of the; absence of mastoid processes in the; platforms built by the; alarmed at the sight of a turtle; using a stick as a lever; using missiles; using the leaves of the Pandanus as a night covering; direction of the hair on the arms of the; its aberrant characters; supposed evolution of the; voice of the; monogamous habits of the; male, beard of the. Oranges, treatment of, by monkeys. Orange-tip butterfly. Orchestia Darwinii, dimorphism of males of. Orchestia Tucuratinga, limbs of. Ordeal, trial by. Oreas canna, colours of. Oreas Derbianus, colours of. Organs, prehensile; utilised for new purposes. Organic scale, von Baer's definition of progress in. Orioles, nidification of. Oriolus, species of, breeding in immature plumage. Oriolus melanocephalus, coloration of the sexes in. Ornaments, prevalence of similar; of male birds; fondness of savages for. Ornamental characters, equal transmission of, to both sexes, in mammals; of monkeys. Ornithoptera croesus. Ornithorhynchus, reptilian tendency of; spur of the male. Orocetes erythrogastra, young of. Orrony, Grotto of. Orsodacna atra, difference of colour in the sexes of. Orsodacna ruficollis. Orthoptera, metamorphosis of; stridulating apparatus of; colours of; rudimentary stridulating organs in female; stridulation of the, and Homoptera, discussed. Ortygornis gularis, pugnacity of the male. Oryctes, stridulation of; sexual differences in the stridulant organs of. Oryx leucoryx, use of the horns of. Osphranter rufus, sexual difference in the colour of. Ostrich, African, sexes and incubation of the. Ostriches, stripes of young. Otaria jubata, mane of the male. Otaria nigrescens, difference in the coloration of the sexes of. Otis bengalensis, love-antics of the male. Otis tarda, throat-pouch of the male; polygamous. Ouzel, ring-, colours and nidification of the. Ouzel, water-, singing in the autumn; colours and nidification of the. Ovibos moschatus, horns of. Ovipositor of insects. Ovis cycloceros, mode of fighting of. Ovule of man. Owen, Prof., on the Corpora Wolffiana; on the great toe in man; on the nictitating membrane and semilunar fold; on the development of the posterior molars in different races of man; on the length of the caecum in the Koala; on the coccygeal vertebrae; on rudimentary structures belonging to the reproductive system; on abnormal conditions of the human uterus; on the number of digits in the Ichthyopterygia; on the canine teeth in man; on the walking of the chimpanzee and orang; on the mastoid processes in the higher apes; on the hairiness of elephants in elevated districts; on the caudal vertebrae of monkeys; classification of mammalia; on the hair in monkeys; on the piscine affinities of the Ichthyosaurians; on polygamy and monogamy among the antelopes; on the horns of Antilocapra Americana; on the musky odour of crocodiles during the breeding season; on the scent-glands of snakes; on the Dugong, Cachalot, and Ornithorhynchus; on the antlers of the red deer; on the dentition of the Camelidae; on the horns of the Irish elk; on the voice of the giraffe, porcupine, and stag; on the laryngeal sac of the gorilla and orang; on the odoriferous glands of mammals; on the effects of emasculation on the vocal organs of men; on the voice of Hylobates agilis; on American monogamous monkeys. Owls, white, new mates found by. Oxynotus, difference of the females of two species of. Pachydermata. Pachytylus migratorius. Paget, on the abnormal development of hairs in man; on the thickness of the skin on the soles of the feet of infants. Pagurus, carrying the female. Painting, pleasure of savages in. Palaemon, chelae of a species of. Palaeornis, sexual differences of colour in. Palaeornis javanicus, colour of beak of. Palaeornis rosa, young of. Palamedea cornuta, spurs on the wings. Paleolithic period. Palestine, habits of the chaffinch in. Pallas, on the perfection of the senses in the Mongolians; on the want of connexion between climate and the colour of the skin; on the polygamous habits of Antilope Saiga; on the lighter colour of horses and cattle in winter in Siberia; on the tusks of the musk-deer; on the odoriferous glands of mammals; on the odoriferous glands of the musk-deer; on winter changes of colour in mammals; on the ideal of female beauty in North China. Palmaris accessorius, muscle variations of the. Pampas, horses of the. Pangenesis, hypothesis of. Panniculus carnosus. Pansch, on the brain of a foetal Cebus apella. Papilio, proportion of the sexes in North American species of; sexual differences of colouring in species of; coloration of the wings in species of. Papilio ascanius. Papilio Sesostris and Childrenae, variability of. Papilio Turnus. Papilionidae, variability in the. Papuans, line of separation between the, and the Malays; beards of the; teeth of. Papuans and Malays, contrast in characters of. Paradise, Birds of; supposed by Lesson to be polygamous; rattling of their quills by; racket-shaped feathers in; sexual differences in colour of; decomposed feathers in; display of plumage by the male; sexual differences in colour of. Paradisea apoda, barbless feathers in the tail of; plumage of; and P. papuana; divergence of the females of; increase of beauty with age. Paradisea papuana, plumage of. Paraguay, Indians of, eradication of eyebrows and eyelashes by. Parallelism of development of species and languages. Parasites, on man and animals; as evidence of specific identity or distinctness; immunity from, correlated with colour. Parental feeling in earwigs, starfishes, and spiders; affection, partly a result of natural selection. Parents, age of, influence upon sex of offspring. Parinae, sexual difference of colour in. Park, Mungo, negro-women teaching their children to love the truth; his treatment by the negro-women; on negro opinions of the appearance of white men. Parker, Mr., no bird or reptile in line of mammalian descent. Parrakeet, young of; Australian, variation in the colour of the thighs of a male. Parrot, racket-shaped feathers in the tail of a; instance of benevolence in a. Parrots, change of colour in; imitative faculties of; living in triplets; affection of; colours and nidification of the; immature plumage of the; colours of; sexual differences of colour in; musical powers of. Parthenogenesis in the Tenthredinae; in Cynipidae; in Crustacea. Partridge, monogamous; proportion of the sexes in the; Indian; female. Partridge-"dances." Partridges, living in triplets; spring coveys of male; distinguishing persons. Parus coeruleus. Passer, sexes and young of. Passer brachydactylus. Passer domesticus. Passer montanus. Patagonians, self-sacrifice by; marriages of. Patterson, Mr., on the Agrionidae. Patteson, Bishop, decrease of Melanesians. Paulistas of Brazil. Pavo cristatus. Pavo muticus, possession of spurs by the female. Pavo nigripennis. Payaguas Indians, thin legs and thick arms of the. Payan, Mr., on the proportion of the sexes in sheep. Peacock, polygamous; sexual characters of; pugnacity of the; Javan, possessing spurs; rattling of the quills by; elongated tail-coverts of the; love of display of the; ocellated spots of the; inconvenience of long tail of the, to the female; continued increase of beauty of the. Peacock-butterfly. Peafowl, preference of females for a particular male; first advances made by the female. Pediculi of domestic animals and man. Pedigree of man. Pedionomus torquatus, sexes of. Peel, J., on horned sheep. Peewit, wing-tubercles of the male. Pelagic animals, transparency of. Pelecanus erythrorhynchus, horny crest on the beak of the male, during the breeding season. Pelecanus onocrotalus, spring plumage of. Pelele, an African ornament. Pelican, blind, fed by his companions; young, guided by old birds; pugnacity of the male. Pelicans, fishing in concert. Pelobius Hermanni, stridulation of. Pelvis, alteration of, to suit the erect attitude of man; differences of the, in the sexes of man. Penelope nigra, sound produced by the male. Pennant, on the battles of seals; on the bladder-nose seal. Penthe, antennal cushions of the male. Perch, brightness of male, during breeding season. Peregrine falcon, new mate found by. Period of variability, relation of, to sexual selection. Periodicity, vital, Dr. Laycock on. Periods, lunar, followed by functions in man and animals. Periods of life, inheritance at corresponding. Perisoreus canadensis, young of. Peritrichia, difference of colour in the sexes of a species of. Periwinkle. Pernis cristata. Perrier, M., on sexual selection; on bees. Perseverance, a characteristic of man. Persians, said to be improved by intermixture with Georgians and Circassians. Personnat, M., on Bombyx Yamamai. Peruvians, civilisation of the, not foreign. Petrels, colours of. Petrocincla cyanea, young of. Petrocossyphus. Petronia. Pfeiffer, Ida, on Javan ideas of beauty. Phacochoerus aethiopicus, tusks and pads of. Phalanger, Vulpine, black varieties of the. Phalaropus fulicarius. Phalaropus hyperboreus. Phanaeus. Phanaeus carnifex, variation of the horns of the male. Phanaeus faunus, sexual differences of. Phanaeus lancifer. Phaseolarctus cinereus, taste for rum and tobacco. Phasgonura viridissima, stridulation of. Phasianus Soemmerringii. Phasianus versicolor. Phasianus Wallichii. Pheasant, polygamous; and black grouse, hybrids of; production of hybrids with the common fowl; immature plumage of the. Pheasant, Amherst, display of. Pheasant, Argus, display of plumage by the male; ocellated spots of the; gradation of characters in the. Pheasant, Blood- Pheasant, Cheer. Pheasant, Eared, length of the tail in the; sexes alike in the. Pheasant, Fire-backed, possessing spurs. Pheasant, Golden, display of plumage by the male; age of mature plumage in the; sex of young, ascertained by pulling out head-feathers. Pheasant, Kalij, drumming of the male. Pheasant, Reeve's, length of the tail in. Pheasant, Silver, triumphant male, deposed on account of spoiled plumage; sexual coloration of the. Pheasant, Soemmerring's. Pheasant, Tragopan, display of plumage by the male; marking of the sexes of the. Pheasants, period of acquisition of male characters in the family of the; proportion of sexes in chicks of; length of the tail in. Philters, worn by women. Phoca groenlandica, sexual difference in the coloration of. Phoenicura ruticilla. Phosphorescence of insects. Phryganidae, copulation of distinct species of. Phryniscus nigricans. Physical inferiority, supposed, of man. Pickering, on the number of species of man. Picton, J.A., on the soul of man. Picus auratus. Picus major. Pieris. Pigeon, female, deserting a weakened mate; carrier, late development of the wattle in; pouter, late development of crop in; domestic, breeds and sub-breeds of. Pigeons, nestling, fed by the secretion of the crop of both parents; changes of plumage in; transmission of sexual peculiarities in; Belgian, with black-streaked males; changing colour after several moultings; numerical proportion of the sexes in; cooing of; variations in plumage of; display of plumage by male; local memory of; antipathy of female, to certain males; pairing of; profligate male and female; wing-bars and tail-feathers of; supposititious breed of; pouter and carrier, peculiarities of, predominant in males; nidification of; Australian; immature plumage of the. Pigs, origin of the improved breeds of; numerical proportion of the sexes in; stripes of young; tusks of miocene; sexual preference shewn by. Pike, American, brilliant colours of the male, during the breeding season. Pike, reasoning powers of; male, devoured by females. Pike, L.O., on the psychical elements of religion. Pimelia striata, sounds produced by the female. Pinel, hairiness in idiots. Pintail, drake, plumage of; pairing with a wild duck. Pintail Duck, pairing with a widgeon. Pipe-fish, filamentous; marsupial receptacles of the male. Pipits, moulting of the. Pipra, modified secondary wing-feathers of male. Pipra deliciosa. Pirates stridulus, stridulation of. Pitcairn island, half-breeds on. Pithecia leucocephala, sexual differences of colour in. Pithecia Satanas, beard of; resemblance of, to a negro. Pits, suborbital, of Ruminants. Pittidae, nidification of. Placentata. Plagiostomous fishes. Plain-wanderer, Australian. Planariae, bright colours of some. Plantain-eaters, colours and nidification of the; both sexes of, equally brilliant. Plants, cultivated, more fertile than wild; Nageli, on natural selection in; male flowers of, mature before the female; phenomena of fertilisation in. Platalea, change of plumage in. Platyblemus. Platycercus, young of. Platyphyllum concavum. Platyrrhine monkeys. Platysma myoides. Plecostomus, head-tentacles of the males of a species of. Plecostomus barbatus, peculiar beard of the male. Plectropterus gambensis, spurred wings of. Ploceus. Plovers, wing-spurs of; double moult in. Plumage, changes of, inheritance of, by fowls; tendency to analogous variation in; display of, by male birds; changes of, in relation to season; immature, of birds; colour of, in relation to protection. Plumes on the head in birds, difference of, in the sexes. Pneumora, structure of. Podica, sexual difference in the colour of the irides. Poeppig, on the contact of civilised and savage races. Poison, avoidance of, by animals. Poisonous fruits and herbs avoided by animals. Poisons, immunity from, correlated with colour. Polish fowls, origin of the crest in. Pollen and van Dam, on the colours of Lemur macaco. Polyandry, in certain Cyprinidae; among the Elateridae. Polydactylism in man. Polygamy, influence of, upon sexual selection; superinduced by domestication; supposed increase of female births by. In the stickleback. Polygenists. Polynesia, prevalence of infanticide in. Polynesians, wide geographical range of; difference of stature among the; crosses of; variability of; heterogeneity of the; aversion of, to hairs on the face. Polyplectron, number of spurs in; display of plumage by the male; gradation of characters in; female of. Polyplectron chinquis. Polyplectron Hardwickii. Polyplectron malaccense. Polyplectron Napoleonis. Polyzoa. Pomotis. Pontoporeia affinis. Porcupine, mute, except in the rutting season. Pores, excretory, numerical relation of, to the hairs in sheep. Porpitae, bright colours of some. Portax picta, dorsal crest and throat-tuft of; sexual differences of colour in. Portunus puber, pugnacity of. Potamochoerus pencillatus, tusks and facial knobs of the. Pouchet, G., the relation of instinct to intelligence; on the instincts of ants; on the caves of Abou-Simbel; on the immunity of negroes from yellow fever; change of colour in fishes. Pouter pigeon, late development of the large crop in. Powell, Dr., on stridulation. Power, Dr., on the different colours of the sexes in a species of Squilla. Powys, Mr., on the habits of the chaffinch in Corfu. Pre-eminence of man. Preference for males by female birds; shewn by mammals, in pairing. Prehensile organs. Presbytis entellus, fighting of the male. Preyer, Dr., on function of shell of ear; on supernumerary mammae in women. Prichard, on the difference of stature among the Polynesians; on the connection between the breadth of the skull in the Mongolians and the perfection of their senses; on the capacity of British skulls of different ages; on the flattened heads of the Colombian savages; on Siamese notions of beauty; on the beardlessness of the Siamese; on the deformation of the head among American tribes and the natives of Arakhan. Primary sexual organs. Primates, sexual differences of colour in. Primogeniture, evils of. Prionidae, difference of the sexes in colour. Proctotretus multimaculatus. Proctotretus tenuis, sexual difference in the colour of. Profligacy. Progenitors, early, of man. Progress, not the normal rule in human society; elements of. Prong-horn antelope, horns of. Proportions, difference of, in distinct races. Protective colouring in butterflies; in lizards; in birds; in mammals. Protective nature of the dull colouring of female Lepidoptera. Protective resemblances in fishes. Protozoa, absence of secondary sexual characters in. Pruner-Bey, on the occurrence of the supra-condyloid foramen in the humerus of man; on the colour of negro infants. Prussia, numerical proportion of male and female births in. Psocus, proportions of the sexes in. Ptarmigan, monogamous; summer and winter plumage of the; nuptial assemblages of; triple moult of the; protective coloration of. Puff-birds, colours and nidification of the. Pugnacity of fine-plumaged male birds. Pumas, stripes of young. Puppies learning from cats to clean their faces. Pycnonotus haemorrhous, pugnacity of the male; display of under-tail coverts by the male. Pyranga aestiva, male aiding in incubation; male characters in female of. Pyrodes, difference of the sexes in colour. Quadrumana, hands of; differences between man and the; sexual differences of colour in; ornamental characters of; analogy of sexual differences of, with those of man; fighting of males for the females; monogamous habits of; beards of the. Quain, R., on the variation of the muscles in man. Quatrefages, A. de, on the occurrence of a rudimentary tail in man; on variability; on the moral sense as a distinction between man and animals; civilised men stronger than savages; on the fertility of Australian women with white men; on the Paulistas of Brazil; on the evolution of the breeds of cattle; on the Jews; on the liability of negroes to tropical fevers after residence in a cold climate; on the difference between field-and house-slaves; on the influence of climate on colour; colours of annelids; on the Ainos; on the women of San Giuliano. Quechua, see Quichua. Querquedula acuta. Quetelet, proportion of sexes in man; relative size in man and woman. Quichua Indians; local variation of colour in the; no grey hair among the; hairlessness of the; long hair of the. Quiscalus major, proportions of the sexes of, in Florida and Honduras. Rabbit, white tail of the. Rabbits, domestic, elongation of the skull in; modification of the skull in, by the lopping of the ear; danger-signals of; numerical proportion of the sexes in. Races, distinctive characters of; or species of man; crossed, fertility or sterility of; of man, variability of the; of man, resemblance of, in mental characters; formation of; of man, extinction of; effects of the crossing of; of man, formation of the; of man, children of the; beardless, aversion of, to hairs on the face. Raffles, Sir S., on the banteng. Rafts, use of. Rage, manifested by animals. Raia batis, teeth of. Raia clavata, female spined on the back; sexual difference in the teeth of. Raia maculata, teeth of. Rails, spur-winged. Ram, mode of fighting of the; African, mane of an; fat-tailed. Rameses II., features of. Ramsay, Mr., on the Australian musk-duck; on the regent-bird; on the incubation of Menura superba. Rana esculenta, vocal sacs of. Rat, common, general dispersion of, a consequence of superior cunning; supplantation of the native in New Zealand, by the European rat; common, said to be polygamous; numerical proportion of the sexes in. Rats, enticed by essential oils. Rationality of birds. Rattlesnakes, difference of the sexes in the; rattles as a call. Raven, vocal organs of the; stealing bright objects; pied, of the Feroe Islands. Rays, prehensile organs of male. Razor-bill, young of the. Reade, Winwood, suicide among savages in Africa; mulattoes not prolific; effect of castration of horned sheep; on the Guinea sheep; on the occurrence of a mane in an African ram; on singing of negroes; on the negroes' appreciation of the beauty of their women; on the admiration of negroes for a black skin; on the idea of beauty among negroes; on the Jollofs; on the marriage-customs of the negroes. Reason in animals. Redstart, American, breeding in immature plumage. Redstarts, new mates found by. Reduvidae, stridulation of. Reed-bunting, head-feathers of the male; attacked by a bullfinch. Reefs, fishes frequenting. Reeks, H., retention of horns by breeding deer; cow rejected by a bull; destruction of piebald rabbits by cats. Regeneration, partial, of lost parts in man. Regent bird. Reindeer, horns of the; battles of; horns of the female; antlers of, with numerous points; winter change of the; sexual preferences shown by. Relationship, terms of. Religion, deficiency of among certain races; psychical elements of. Remorse, deficiency of, among savages. Rengger, on the diseases of Cebus Azarae; on the diversity of the mental faculties of monkeys; on the Payaguas Indians; on the inferiority of Europeans to savages in their senses; revenge taken by monkeys; on maternal affection in a Cebus; on the reasoning powers of American monkeys; on the use of stones by monkeys for cracking hard nuts; on the sounds uttered by Cebus Azarae; on the signal-cries of monkeys; on the polygamous habits of Mycetes caraya; on the voice of the howling monkeys; on the odour of Cervus campestris; on the beards of Mycetes caraya and Pithecia Satanas; on the colours of Felis mitis; on the colours of Cervus paludosus; on sexual differences of colour in Mycetes; on the colour of the infant Guaranys; on the early maturity of the female of Cebus Azarae; on the beards of the Guaranys; on the emotional notes employed by monkeys; on American polygamous monkeys. Representative species, of birds. Reproduction, unity of phenomena of, throughout the mammalia; period of, in birds. Reproductive system, rudimentary structures in the; accessory parts of. Reptiles. Reptiles and birds, alliance of. Resemblances, small, between man and the apes. Retrievers, exercise of reasoning faculties by. Revenge, manifested by animals. Reversion, perhaps the cause of some bad dispositions. Rhagium, difference of colour in the sexes of a species of. Rhamphastos carinatus. Rhea Darwinii. Rhinoceros, nakedness of; horns of; horns of, used defensively; attacking white or grey horses. Rhynchaea, sexes and young of. Rhynchaea australis. Rhynchaea bengalensis. Rhynchaea capensis. Rhythm, perception of, by animals. Richard, M., on rudimentary muscles in man. Richardson, Sir J., on the pairing of Tetrao umbellus; on Tetrao urophasianus; on the drumming of grouse; on the dances of Tetrao phasianellus; on assemblages of grouse; on the battles of male deer; on the reindeer; on the horns of the musk-ox; on antlers of the reindeer with numerous points; on the moose; on the Scotch deerhound. Richter, Jean Paul, on imagination. Riedel, on profligate female pigeons. Riley, Mr., on mimicry in butterflies; bird's disgust at taste of certain caterpillars. Ring-ouzel, colours and nidification of the. Ripa, Father, on the difficulty of distinguishing the races of the Chinese. Rivalry, in singing, between male birds. River-hog, African, tusks and knobs of the. Rivers, analogy of, to islands. Roach, brightness of the male during breeding-season. Robbery, of strangers, considered honourable. Robertson, Mr., remarks on the development of the horns in the roebuck and red deer. Robin, pugnacity of the male; autumn song of the; female singing of the; attacking other birds with red in their plumage; young of the. Robinet, on the difference of size of the male and female cocoons of the silk-moth. Rodents, uterus in the; absence of secondary sexual characters in; sexual differences in the colours of. Roe, winter changes of the. Rohfs, Dr., Caucasian features in negro; fertility of mixed races in Sahara; colours of birds in Sahara; ideas of beauty amongst the Bornuans. Rolle, F., on the origin of man; on a change in German families settled in Georgia. Roller, harsh cry of. Romans, ancient, gladiatorial exhibitions of the. Rook, voice of the. Rossler, Dr., on the resemblance of the lower surface of butterflies to the bark of trees. Rostrum, sexual difference in the length of in some weevils. Royer, Madlle., mammals giving suck. Rudimentary organs, origin of. Rudiments, presence of, in languages. Rudolphi, on the want of connexion between climate and the colour of the skin. Ruff, supposed to be polygamous; proportion of the sexes in the; pugnacity of the; double moult in; duration of dances of; attraction of the, to bright objects. Ruminants, male, disappearance of canine teeth in; generally polygamous; suborbital pits of; sexual differences of colour in. Rupicola crocea, display of plumage by the male. Ruppell, on canine teeth in deer and antelopes. Russia, numerical proportion of male and female births in. Ruticilla. Rutimeyer, Prof., on the physiognomy of the apes; on tusks of miocene boar; on the sexual differences of monkeys. Rutlandshire, numerical proportion of male and female births in. Sachs, Prof., on the behaviour of the male and female elements in fertilisation. Sacrifices, human. Sagittal crest, in male apes and Australians. Sahara, fertility of mixed races in; birds of the; animal inhabitants of the. Sailors, growth of, delayed by conditions of life; long-sighted. Sailors and soldiers, difference in the proportions of. St. John, Mr., on the attachment of mated birds. St. Kilda, beards of the inhabitants of. Salmo eriox, and Salmo umbla, colouring of the male, during the breeding season. Salmo lycaodon. Salmo salar. Salmon, leaping out of fresh water; male, ready to breed before the female; proportion of the sexes in; male, pugnacity of the; male, characters of, during the breeding season; spawning of the; breeding of immature male. Salvin, O., inheritance of mutilated feathers; on the Humming-birds; on the numerical proportion of the sexes in Humming-birds; on Chamaepetes and Penelope; on Selasphorus platycercus; Pipra deliciosa; on Chasmorhynchus. Samoa Islands, beardlessness of the natives of. Sandhoppers, claspers of male. Sand-skipper. Sandwich Islands, variation in the skulls of the natives of the; decrease of native population; population of; superiority of the nobles in the. Sandwich Islanders, lice of. San-Giuliano, women of. Santali, recent rapid increase of the; Mr. Hunter on the. Saphirina, characters of the males of. Sarkidiornis melanonotus, characters of the young. Sars, O., on Pontoporeia affinis. Saturnia carpini, attraction of males by the female. Saturnia Io, difference of coloration in the sexes of. Saturniidae, coloration of the. Savage, Dr., on the fighting of the male gorillas; on the habits of the gorilla. Savage and Wyman on the polygamous habits of the gorilla. Savages, uniformity of, exaggerated; long-sighted; rate of increase among, usually small; retention of the prehensile power of the feet by; imitative faculties of; causes of low morality of; tribes of, supplanting one another; improvements in the arts among; arts of; fondness of, for rough music; on long-enduring fashions among; attention paid by, to personal appearance; relation of the sexes among. Saviotti, Dr., division of malar bone. Saw-fly, pugnacity of a male. Saw-flies, proportions of the sexes in. Saxicola rubicola, young of. Scalp, motion of the. Scent-glands in snakes. Schaaffhausen, Prof., on the development of the posterior molars in different races of man; on the jaw from La Naulette; on the correlation between muscularity and prominent supra-orbital ridges; on the mastoid processes of man; on modifications of the cranial bones; on human sacrifices; on the probable speedy extermination of the anthropomorphous apes; on the ancient inhabitants of Europe; on the effects of use and disuse of parts; on the superciliary ridge in man; on the absence of race-differences in the infant skull in man; on ugliness. Schaum, H., on the elytra of Dytiscus and Hydroporus. Scherzer and Schwarz, measurements of savages. Schelver, on dragon-flies. Schiodte, on the stridulation of Heterocerus. Schlegel, F. von, on the complexity of the languages of uncivilised peoples. Schlegel, Prof., on Tanysiptera. Schleicher, Prof, on the origin of language. Schomburgk, Sir R., on the pugnacity of the male musk-duck of Guiana; on the courtship of Rupicola crocea. Schoolcraft, Mr., on the difficulty of fashioning stone implements. Schopenhauer, on importance of courtship to mankind. Schweinfurth, complexion of negroes. Sciaena aquila. Sclater, P.L., on modified secondary wing-feathers in the males of Pipra; on elongated feathers in nightjars; on the species of Chasmorhynchus; on the plumage of Pelecanus onocrotalus; on the plantain-eaters; on the sexes and young of Tadorna variegata; on the colours of Lemur macaco; on the stripes in asses. Scolecida, absence of secondary sexual characters in. Scolopax frenata, tail feathers of; Scolopax gallinago, drumming of. Scolopax javensis, tail-feathers of. Scolopax major, assemblies of. Scolopax Wilsonii, sound produced by. Scolytus, stridulation of. Scoter-duck, black, sexual difference in coloration of the; bright beak of male. Scott, Dr., on idiots smelling their food. Scott, J., on the colour of the beard in man. Scrope, on the pugnacity of the male salmon; on the battles of stags. Scudder, S.H., imitation of the stridulation of the Orthoptera; on the stridulation of the Acridiidae; on a Devonian insect; on stridulation. Sculpture, expression of the ideal of beauty by. Sea-anemones, bright colours of. Sea-bear, polygamous. Sea-elephant, male, structure of the nose of the; polygamous. Sea-lion, polygamous. Seal, bladder-nose. Seals, their sentinels generally females; evidence furnished by, on classification; polygamous habits of; battles of male; canine teeth of male; sexual differences; pairing of; sexual peculiarities of; in the coloration of; appreciation of music by. Sea-scorpion, sexual differences in. Season, changes of colour in birds, in accordance with the; changes of plumage of birds in relation to. Seasons, inheritance at corresponding. Sebituani, African chief, trying to alter a fashion. Sebright Bantam. Secondary sexual characters; relations of polygamy to; transmitted through both sexes; gradation of, in birds. Sedgwick, W., on hereditary tendency to produce twins. Seemann, Dr., on the different appreciation of music by different peoples; on the effects of music. Seidlitz, on horns of reindeer. Selasphorus platycercus, acuminate first primary of the male. Selby, P.J., on the habits of the black and red grouse. Selection as applied to primeval man. Selection, double. Selection, injurious forms of, in civilised nations. Selection of male by female birds. Selection, methodical, of Prussian grenadiers. Selection, sexual, explanation of; influence of, on the colouring of Lepidoptera. Selection, sexual and natural, contrasted. Self-command, habit of, inherited; estimation of. Self-consciousness, in animals. Self-preservation, instinct of. Self-sacrifice, by savages; estimation of. Semilunar fold. Semnopithecus, long hair on the heads of species of. Semnopithecus chrysomelas, sexual differences of colour in. Semnopithecus comatus, ornamental hair on the head of. Semnopithecus frontatus, beard etc., of. Semnopithecus nasica, nose of. Semnopithecus nemaeus, colouring of. Semnopithecus rubicundus, ornamental hair on the head of. Senses, inferiority of Europeans to savages in the. Sentinels, among animals. Serpents, instinctively dreaded by apes and monkeys. Serranus, hermaphroditism in. Setina, noise produced by. Sex, inheritance limited by. Sexes, relative proportions of, in man; proportions of, sometimes influenced by selection; probable relation of the, in primeval man. Sexual and natural selection, contrasted. Sexual characters, effects of the loss of; limitation of. Sexual characters, secondary; relations of polygamy to; transmitted through both sexes; gradation of, in birds. Sexual differences in man. Sexual selection, explanation of; influence of, on the colouring of Lepidoptera; objections to; action of, in mankind. Sexual selection in spiders. Sexual selection, supplemental note on. Sexual similarity. Shaler, Prof., sizes of sexes in whales. Shame. Sharks, prehensile organs of male. Sharpe, Dr., Europeans in the tropics. Sharpe, R.B., on Tanysiptera sylvia; on Ceryle; on the young male of Dacelo Gaudi-chaudi. Shaw, Mr., on the pugnacity of the male salmon. Shaw, J., on the decorations of birds. Sheep, danger-signals of; sexual differences in the horns of; horns of; domestic, sexual differences of, late developed; numerical proportion of the sexes in; inheritance of horns by one sex; effect of castration; mode of fighting of; arched foreheads of some. Sheep, Merino, loss of horns in females of; horns of. Shells, difference in form of, in male and female Gasteropoda; beautiful colours and shapes of. Shield-drake, pairing with a common duck; New Zealand, sexes and young of. Shooter, J., on the Kaffirs; on the marriage-customs of the Kaffirs. Shrew-mice, odour of. Shrike, Drongo. Shrikes, characters of young. Shuckard, W.E., on sexual differences in the wings of Hymenoptera. Shyness of adorned male birds; Siagonium, proportions of the sexes in; dimorphism in males of. Siam, proportion of male and female births in. Siamese, general beardlessness of the; notions of beauty of the; hairy family of. Sidgwick, H., on morality in hypothetical bee community; our actions not entirely directed by pain and pleasure. Siebold, C.T., von, on the proportion of sexes in the Apus; on the auditory apparatus of the stridulent Orthoptera. Sight, inheritance of long and short. Signal-cries of monkeys. Silk-moth, proportion of the sexes in; Ailanthus, Prof. Canestrini, on the destruction of its larvae by wasps; difference of size of the male and female cocoons of the; pairing of the. Simiadae, their origin and divisions. Similarity, sexual. Singing of the Cicadae and Fulgoridae; of tree-frogs; of birds, object of the. Sirenia, nakedness of. Sirex juvencus. Siricidae, difference of the sexes in. Siskin, pairing with a canary. Sitana, throat-pouch of the males of. Size, relative, of the sexes of insects. Skin, dark colour of, a protection against heat. Skin, movement of the; nakedness of, in man; colour of the. Skin and hair, correlation of colour of. Skull, variation of, in man; cubic contents of, no absolute test of intellect; Neanderthal, capacity of the; causes of modification of the; difference of, in form and capacity, in different races of men; variability of the shape of the; differences of, in the sexes in man; artificial modification of the shape of. Skunk, odour emitted by the; white tail of, protective. Slavery, prevalence of; of women. Slaves, difference between field-and house-slaves. Sloth, ornaments of male. Smell, sense of, in man and animals. Smith, Adam, on the basis of sympathy. Smith, Sir A., on the recognition of women by male Cynocephali; on revenge by a baboon; on an instance of memory in a baboon; on the retention of their colour by the Dutch in South Africa; on the polygamy of the South African antelopes; on the polygamy of the lion; on the proportion of the sexes in Kobus ellipsiprymnus; on Bucephalus capensis; on South African lizards; on fighting gnus; on the horns of rhinoceroses; on the fighting of lions; on the colours of the Cape Eland; on the colours of the gnu; on Hottentot notions of beauty; disbelief in communistic marriages. Smith, F., on the Cynipidae and Tenthredinidae; on the relative size of the sexes of Aculeate Hymenoptera; on the difference between the sexes of ants and bees; on the stridulation of Trox sabulosus; on the stridulation of Mononychus pseudacori. Smynthurus luteus, courtship of. Snakes, sexual differences of; mental powers of; male, ardency of. "Snarling muscles." Snipe, drumming of the; coloration of the. Snipe, painted, sexes and young of. Snipe, solitary, assemblies of. Snipes, arrival of male before the female; pugnacity of male; double moult in. Snow-goose, whiteness of the. Sociability, the sense of duty connected with; impulse to, in animals; manifestations of, in man; instinct of, in animals. Social animals, affection of, for each other; defence of, by the males. Sociality, probable, of primeval men; influence of, on the development of the intellectual faculties; origin of, in man. Soldiers, American, measurements of. Soldiers and sailors, difference in the proportions of. Solenostoma, bright colours and marsupial sac of the females of. Song, of male birds appreciated by their females; want of, in brilliant plumaged birds; of birds. Sorex, odour of. Sounds, admired alike by man and animals; produced by fishes; produced by male frogs and toads; instrumentally produced by birds. Spain, decadence of. Sparassus smaragdulus, difference of colour in the sexes of. Sparrow, pugnacity of the male; acquisition of the Linnet's song by a; coloration of the; immature plumage of the. Sparrow, white-crowned, young of the. Sparrows, house-and tree-. Sparrows, new mates found by. Sparrows, sexes and young of; learning to sing. Spathura Underwoodi. Spawning of fishes. Spear, used before dispersion of man. Species, causes of the advancement of; distinctive characters of; or races of man; sterility and fertility of, when crossed; supposed, of man; gradation of; difficulty of defining; representative, of birds; of birds, comparative differences between the sexes of distinct. Spectrum femoratum, difference of colour in the sexes of. Speech, connection between the brain and the faculty of; connection of intonation with music. Spel, of the black-cock. Spencer, Herbert, on the influence of food on the size of the jaws; on the dawn of intelligence; on the origin of the belief in spiritual agencies; on the origin of the moral sense; on music. Spengel, disagrees with explanation of man's hairlessness. Sperm-whales, battles of male. Sphingidae, coloration of the. Sphinx, Humming-bird. Sphinx, Mr. Bates on the caterpillar of a. Sphinx moth, musky odour of. Spiders, parental feeling in; male, more active than female; proportion of the sexes in; secondary sexual characters of; courtship of male; attracted by music; male, small size of. Spilosoma menthastri, rejected by turkeys. Spine, alteration of, to suit the erect attitude of man. Spirits, fondness of monkeys for. Spiritual agencies, belief in, almost universal. Spiza cyanea and ciris. Spoonbill, Chinese, change of plumage in. Spots, retained throughout groups of birds; disappearance of, in adult mammals. Sprengel, C.K., on the sexuality of plants. Springboc, horns of the. Sproat, Mr., on the extinction of savages in Vancouver Island; on the eradication of facial hair by the natives of Vancouver Island; on the eradication of the beard by the Indians of Vancouver Island. Spurs, occurrence of, in female fowls; development of, in various species of Phasianidae; of Gallinaceous birds; development of, in female Gallinaceae. Squilla, different colours of the sexes of a species of. Squirrels, battles of male; African, sexual differences in the colouring of; black. Stag, long hairs of the throat of; horns of the; battles of; horns of the, with numerous branches; bellowing of the; crest of the. Stag-beetle, numerical proportion of sexes of; use of jaws; large size of male; weapons of the male. Stainton, H.T., on the numerical proportion of the sexes in the smaller moths; habits of Elachista rufocinerea; on the coloration of moths; on the rejection of Spilosoma menthastri by turkeys; on the sexes of Agrotis exclamationis. Staley, Bishop, mortality of infant Maories. Stallion, mane of the. Stallions, two, attacking a third; fighting; small canine teeth of. Stansbury, Captain, observations on pelicans. Staphylinidae, hornlike processes in male. Starfishes, parental feeling in; bright colours of some. Stark, Dr., on the death-rate in towns and rural districts; on the influence of marriage on mortality; on the higher mortality of males in Scotland. Starling, American field-, pugnacity of male. Starling, red-winged, selection of a mate by the female. Starlings, three, frequenting the same nest; new mates found by. Statues, Greek, Egyptian, Assyrian, etc., contrasted. Stature, dependence of, upon local influences. Staudinger, Dr., on breeding Lepidoptera; his list of Lepidoptera. Staunton, Sir G., hatred of indecency a modern virtue. Stealing of bright objects by birds. Stebbing, T.R., on the nakedness of the human body. Stemmatopus. Stendhal, see Bombet. Stenobothrus pratorum, stridulation. Stephen, Mr. L., on the difference in the minds of men and animals; on general concepts in animals; distinction between material and formal morality. Sterility, general, of sole daughters; when crossed, a distinctive character of species; under changed conditions. Sterna, seasonal change of plumage in. Stickleback, polygamous; male, courtship of the; male, brilliant colouring of, during the breeding season; nidification of the. Sticks used as implements and weapons by monkeys. Sting in bees. Stokes, Captain, on the habits of the great bower-bird. Stoliczka, Dr., on colours in snakes. Stoliczka, on the pre-anal pores of lizards. Stonechat, young of the. Stone implements, difficulty of making; as traces of extinct tribes. Stones, used by monkeys for breaking hard fruits and as missiles; piles of. Stork, black, sexual differences in the bronchi of the; red beak of the. Storks, sexual difference in the colour of the eyes of. Strange, Mr., on the satin bowerbird. Strepsiceros kudu, horns of; markings of. Stretch, Mr., on the numerical proportion in the sexes of chickens. Stridulation, by males of Theridion; of Hemiptera; of the Orthoptera and Homoptera discussed; of beetles. Stripes, retained throughout groups of birds; disappearance of, in adult mammals. Strix flammea. Structure, existence of unserviceable modifications of. Struggle for existence, in man. Struthers, Dr., on the occurrence of the supra-condyloid foramen in the humerus of man. Sturnella ludoviciana, pugnacity of the male. Sturnus vulgaris. Sub-species. Suffering, in strangers, indifference of savages to. Suicide, formerly not regarded as a crime; rarely practised among the lowest savages. Suidae, stripes of the young. Sulivan, Sir B.J., on speaking of parrots; on two stallions attacking a third. Sumatra, compression of the nose by the Malays of. Sumner, Archb., man alone capable of progressive improvement. Sun-birds, nidification of. Superciliary ridge in man. Supernumerary digits, more frequent in men than in women; inheritance of; early development of. Superstitions, prevalence of. Superstitious customs. Supra-condyloid foramen in the early progenitors of man. Suspicion, prevalence of, among animals. Swallow-tail butterfly. Swallows deserting their young. Swan, black, wild, trachea of the; white, young of; red beak of the; black-necked. Swans, young. Swaysland, Mr., on the arrival of migratory birds. Swifts, migration of. Swinhoe, R., on the common rat in Formosa and China; behaviour of lizards when caught; on the sounds produced by the male hoopoe; on Dicrurus macrocercus and the spoonbill; on the young of Ardeola; on the habits of Turnix; on the habits of Rhynchaea bengalensis; on Orioles breeding in immature plumage. Sylvia atricapilla, young of. Sylvia cinerea, aerial love-dance of the male. Sympathy, among animals; its supposed basis. Sympathies, gradual widening of. Syngnathous fishes, abdominal pouch in male. Sypheotides auritus, acuminated primaries of the male; ear-tufts of. Tabanidae, habits of. Tadorna variegata, sexes and young of. Tadorna vulpanser. Tahitians, compression of the nose by the. Tail, rudimentary, occurrence of, in man; convoluted body in the extremity of the; absence of, in man and the higher apes; variability of, in species of Macacus and in baboons; presence of, in the early progenitors of man; length of, in pheasants; difference of length of the, in the two sexes of birds. Tait, Lawson, on the effects of natural selection on civilised nations. Tanager, scarlet, variation in the male. Tanagra aestiva, age of mature plumage in. Tanagra rubra, young of. Tanais, absence of mouth in the males of some species of; relations of the sexes in; dimorphic males of a species of. Tankerville, Earl, on the battles of wild bulls. Tanysiptera, races of, determined from adult males. Tanysiptera sylvia, long tail-feathers of. Taphroderes distortus, enlarged left mandible of the male. Tapirs, longitudinal stripes of young. Tarsi, dilatation of front, in male beetles. Tarsius. Tasmania, half-castes killed by the natives of. Tasmanians, extinction of. Taste, in the Quadrumana. Tattooing, universality of. Taylor, G., on Quiscalus major. Taylor, Rev. R., on tattooing in New Zealand. Tea, fondness of monkeys for. Teal, constancy of. Tear-sacs, of Ruminants. Teebay, Mr., on changes of plumage in spangled Hamburg fowls. Teeth, rudimentary incisor, in Ruminants; posterior molar, in man; wisdom; diversity of; canine, in the early progenitors of man; canine, of male mammals; in man, reduced by correlation; staining of the; front, knocked out or filed by some savages. Tegetmeier, Mr., on the transmission of colours in pigeons by one sex alone; numerical proportion of male and female births in dogs; on the abundance of male pigeons; on the wattles of game-cocks; on the courtship of fowls; on the loves of pigeons; on dyed pigeons; blue dragon pigeons. Tembeta, S. American ornament. Temper, in dogs and horses, inherited. Tench, proportions of the sexes in the; brightness of male, during breeding season. Tenebrionidae, stridulation of. Tennent, Sir J.E., on the tusks of the Ceylon Elephant; on the frequent absence of beard in the natives of Ceylon; on the Chinese opinion of the aspect of the Cingalese. Tennyson, A., on the control of thought. Tenthredinidae, proportions of the sexes in; fighting habits of male; difference of the sexes in. Tephrodornis, young of. Terai, in India. Termites, habits of. Terns, white; and black. Terns, seasonal change of plumage in. Terror, common action of, upon the lower animals and man. Testudo elegans. Testudo nigra. Tetrao cupido, battles of; sexual difference in the vocal organs of. Tetrao phasianellus, dances of; duration of dances of. Tetrao scoticus. Tetrao tetrix, pugnacity of the male. Tetrao umbellus, pairing of; battles of; drumming of the male. Tetrao urogalloides, dances of. Tetrao urogallus, pugnacity of the male. Tetrao urophasianus, inflation of the oesophagus in the male. Thamnobia, young of. Thecla, sexual differences of colouring in species of. Thecla rubi, protective colouring of. Thecophora fovea. Theognis, selection in mankind. Theridion, stridulation of males of. Theridion lineatum. Thomisus citreus, and Thomisus floricolens, difference of colour in the sexes of. Thompson, J.H., on the battles of sperm-whales. Thompson, W., on the colouring of the male char during the breeding season; on the pugnacity of the males of Gallinula chloropus; on the finding of new mates by magpies; on the finding of new mates by Peregrine falcons. Thorax, processes of, in male beetles. Thorell, T., on the proportion of sexes in spiders. Thornback, difference in the teeth of the two sexes of the. Thoughts, control of. Thrush, pairing with a blackbird; colours and nidification of the. Thrushes, characters of young. Thug, remorse of a. Thumb, absence of, in Ateles and Hylobates. Thury, M., on the numerical proportion of male and female births among the Jews. Thylacinus, possession of the marsupial sac by the male. Thysanura. Tibia, dilated, of the male Crabro cribrarius. Tibia and femur, proportions of, in the Aymara Indians. Tierra del Fuego, marriage-customs of. Tiger, colours and markings of the. Tigers, depopulation of districts by, in India. Tillus elongatus, difference of colour in the sexes of. Timidity, variability of, in the same species. Tinca vulgaris. Tipula, pugnacity of male. Tits, sexual difference of colour in. Toads, male, treatment of ova by some; male, ready to breed before the female. Todas, infanticide and proportion of sexes; practice polyandry; choice of husbands amongst. Toe, great, condition of, in the human embryo. Tomicus villosus, proportion of the sexes in. Tomtit, blue, sexual difference of colour in the. Tonga Islands, beardlessness of the natives of. Tooke, Horne, on language. Tools, flint; used by monkeys; use of. Topknots in birds. Tortoise, voice of the male. Tortures, submitted to by American savages. Totanus, double moult in. Toucans, colours and nidification of the; beaks and ceres of the. Towns, residence in, a cause of diminished stature. Toynbee, J., on the external shell of the ear in man. Trachea, convoluted and imbedded in the sternum, in some birds; structure of the, in Rhynchaea. Trades, affecting the form of the skull. Tragelaphus, sexual differences of colour in. Tragelaphus scriptus, dorsal crest of; markings of. Tragopan, swelling of the wattles of the male, during courtship; display of plumage by the male; marking of the sexes of the. Tragops dispar, sexual difference in the colour of. Training, effect of, on the mental difference between the sexes of man. Transfer of male characters to female birds. Transmission, equal, of ornamental characters, to both sexes in mammals. Traps, avoidance of, by animals; use of. Treachery, to comrades, avoidance of, by savages. Tremex columbae. Tribes, extinct; extinction of. Trichius, difference of colour in the sexes of a species of. Trigla. Trigonocephalus, noise made by tail of. Trimen, R., on the proportion of the sexes in South African butterflies; on the attraction of males by the female Lasiocampa quercus; on Pneumora; on difference of colour in the sexes of beetles; on moths brilliantly coloured beneath; on mimicry in butterflies; on Gynanisa Isis, and on the ocellated spots of Lepidoptera; on Cyllo Leda. Tringa, sexes and young of. Tringa cornuta. Triphaena, coloration of the species of. Tristram, H.B., on unhealthy districts in North Africa; on the habits of the chaffinch in Palestine; on the birds of the Sahara; on the animals inhabiting the Sahara. Triton cristatus. Triton palmipes. Triton punctatus. Troglodyte skulls, greater than those of modern Frenchmen. Troglodytes vulgaris. Trogons, colours and nidification of the. Tropic-birds, white only when mature. Tropics, freshwater fishes of the. Trout, proportion of the sexes in; male, pugnacity of the. Trox sabulosus, stridulation of. Truth, not rare between members of the same tribe; more highly appreciated by certain tribes. Tulloch, Major, on the immunity of the negro from certain fevers. Tumbler, almond, change of plumage in the. Turdus merula, young of. Turdus migratorius. Turdus musicus. Turdus polyglottus, young of. Turdus torquatus. Turkey, wild, pugnacity of young male; wild, notes of the; swelling of the wattles of the male; variety of, with a top-knot; recognition of a dog by a; male, wild, acceptable to domesticated females; wild, first advances made by older females; wild, breast-tuft of bristles of the. Turkey-cock, scraping of the wings of, upon the ground; wild, display of plumage by; fighting habits of. Turner, Prof. W., on muscular fasciculi in man referable to the panniculus carnosus; on the occurrence of the supra-condyloid foramen in the human humerus; on muscles attached to the coccyx in man; on the filum terminale in man; on the variability of the muscles; on abnormal conditions of the human uterus; on the development of the mammary glands; on male fishes hatching ova in their mouths; on the external perpendicular fissure of the brain; on the bridging convolutions in the brain of a chimpanzee. Turnix, sexes of some species of. Turtle-dove, cooing of the. Tuttle, H., on the number of species of man. Tylor, E.B., on emotional cries, gestures, etc., of man; on the origin of the belief in spiritual agencies; remorse for violation of tribal usage in marrying; on the primitive barbarism of civilised nations; on the origin of counting; inventions of savages; on resemblances, of the mental characters in different races of man. Type of structure, prevalence of. Typhaeus, stridulating organs of; stridulation of. Twins, tendency to produce, hereditary. Twite, proportion of the sexes in. Ugliness, said to consist in an approach to the lower animals. Umbrella-bird. Umbrina, sounds produced by. United States, rate of increase in; influence of natural selection on the progress of; change undergone by Europeans in the. Upupa epops, sounds produced by the male. Uraniidae, coloration of the. Uria troile, variety of (=U. lacrymans). Urodela. Urosticte Benjamini, sexual differences in. Use and disuse of parts, effects of; influence of, on the races of man. Uterus, reversion in the; more or less divided, in the human subject; double, in the early progenitors of man. Vaccination, influence of. Vancouver Island, Mr. Sproat on the savages of; natives of, eradication of facial hair by the. Vanellus cristatus, wing tubercles of the male. Vanessae, resemblance of lower surface of, to bark of trees. Variability, causes of; in man, analogous to that in the lower animals; of the races of man; greater in men than in women; period of, relation of the, to sexual selection; of birds; of secondary sexual characters in man. Variation, laws of; correlated; in man; analogous; analogous, in plumage of birds. Variations, spontaneous. Varieties, absence of, between two species, evidence of their distinctness. Variety, an object in nature. Variola, communicable between man and the lower animals. Vaureal, human bones from. Veddahs, monogamous habits of. Veitch, Mr., on the aversion of Japanese ladies to whiskers. Vengeance, instinct of. Venus Erycina, priestesses of. Vermes. Vermiform appendage. Verreaux, M., on the attraction of numerous males by the female of an Australian Bombyx. Vertebrae, caudal, number of in macaques and baboons; of monkeys, partly imbedded in the body. Vertebrata, common origin of the; most ancient progenitors of; origin of the voice in air-breathing. Vesicula prostatica, the homologue of the uterus. Vibrissae, represented by long hairs in the eyebrows. Vidua. Vidua axillaris. Villerme, M., on the influence of plenty upon stature. Vinson, Aug., courtship of male spider; on the male of Epeira nigra. Viper, difference of the sexes in the. Virey, on the number of species of man. Virtues, originally social only; gradual appreciation of. Viscera, variability of, in man. Vlacovich, Prof., on the ischio-pubic muscle. Vocal music of birds. Vocal organs of man; of birds; of frogs; of the Insessores; difference of, in the sexes of birds; primarily used in relation to the propagation of the species. Vogt, Karl, on the origin of species; on the origin of man; on the semilunar fold in man; on microcephalous idiots; on the imitative faculties of microcephalous idiots; on skulls from Brazilian caves; on the evolution of the races of man; on the formation of the skull in women; on the Ainos and negroes; on the increased cranial difference of the sexes in man with race development; on the obliquity of the eye in the Chinese and Japanese. Voice in mammals; in monkeys and man; in man; origin of, in air-breathing vertebrates. Von Baer, see Baer. Vulpian, Prof., on the resemblance between the brains of man and the higher apes. Vultures, selection of a mate by the female; colours of. Waders, young of. Wagner, R., on the occurrence of the diastema in a Kaffir skull; on the bronchi of the black stork. Wagtail, Ray's, arrival of the male before the female. Wagtails, Indian, young of. Waist, proportions of, in soldiers and sailors. Waitz, Prof., on the number of species of man; on the liability of negroes to tropical fevers after residence in a cold climate; on the colour of Australian infants; on the beardlessness of negroes; on the fondness of mankind for ornaments; on negro ideas of female beauty; on Javan and Cochin Chinese ideas of beauty. Waldeyer, M., on the hermaphroditism of the vertebrate embryo. Wales, North, numerical proportion of male and female births in. Walkenaer and Gervais, spider attracted by music; on the Myriapoda. Walker, Alex., on the large size of the hands of labourers' children. Walker, F., on sexual differences in the diptera. Wallace, Dr. A., on the prehensile use of the tarsi in male moths; on the rearing of the Ailanthus silkmoth; on breeding Lepidoptera; proportion of sexes of Bombyx cynthia, B. yamamai, and B. Pernyi reared by; on the development of Bombyx cynthia and B. yamamai; on the pairing of Bombyx cynthia. Wallace, A.R., on the origin of man; on the power of imitation in man; on the use of missiles by the orang; on the varying appreciation of truth among different tribes; on the limits of natural selection in man; on the occurrence of remorse among savages; on the effects of natural selection on civilised nations; on the use of the convergence of the hair at the elbow in the orang; on the contrast in the characters of the Malays and Papuans; on the line of separation between the Papuans and Malays; on the birds of paradise; on the sexes of Ornithoptera Croesus; on protective resemblances; on the relative sizes of the sexes of insects; on Elaphomyia; on the pugnacity of the males of Leptorhynchus angustatus; on sounds produced by Euchirus longimanus; on the colours of Diadema; on Kallima; on the protective colouring of moths; on bright coloration as protective in butterflies; on variability in the Papilionidae; on male and female butterflies, inhabiting different stations; on the protective nature of the dull colouring of female butterflies; on mimicry in butterflies; on the bright colours of caterpillars; on brightly-coloured fishes frequenting reefs; on the coral snakes; on Paradisea apoda; on the display of plumage by male birds of paradise; on assemblies of birds of paradise; on the instability of the ocellated spots in Hipparchia Janira; on sexually limited inheritance; on the sexual coloration of birds; on the relation between the colours and nidification of birds; on the coloration of the Cotingidae; on the females of Paradisea apoda and papuana; on the incubation of the cassowary; on protective coloration in birds; on the Babirusa; on the markings of the tiger; on the beards of the Papuans; on the hair of the Papuans; on the distribution of hair on the human body. Walrus, development of the nictitating membrane in the; tusks of the; use of the tusks by the. Walsh, B.D., on the proportion of the sexes in Papilio Turnus; on the Cynipidae and Cecidomyidae; on the jaws of Ammophila; on Corydalis cornutus; on the prehensile organs of male insects; on the antennae of Penthe; on the caudal appendages of dragonflies; on Platyphyllum concavum; on the sexes of the Ephemeridae; on the difference of colour in the sexes of Spectrum femoratum; on sexes of dragon-flies; on the difference of the sexes in the Ichneumonidae; on the sexes of Orsodacna atra; on the variation of the horns of the male Phanaeas carnifex; on the coloration of the species of Anthocharis. Wapiti, battles of; traces of horns in the female; attacking a man; crest of the male; sexual difference in the colour of the. Warbler, hedge-; young of the. Warblers, superb, nidification of. Wariness, acquired by animals. Warington, R., on the habits of the stickleback; on the brilliant colours of the male stickleback during the breeding season. Wart-hog, tusks and pads of the. Watchmakers, short-sighted. Waterhen. Waterhouse, C.O., on blind beetles; on difference of colour in the sexes of beetles. Waterhouse, G.R., on the voice of Hylobates agilis. Water-ouzel, autumn song of the. Waterton, C., on the Bell-bird; on the pairing of a Canada goose with a Bernicle gander; on hares fighting. Wattles, disadvantageous to male birds in fighting. Weale, J., Mansel, on a South African caterpillar. Wealth, influence of. Weapons, used by man; employed by monkeys; offensive, of males; of mammals. Weaver-bird. Weaver-birds, rattling of the wings of; assemblies of. Webb, Dr., on the wisdom teeth. Wedderburn, Mr., assembly of black game. Wedgwood, Hensleigh, on the origin of language. Weevils, sexual difference in length of snout in some. Weir, Harrison, on the numerical proportion of the sexes in pigs and rabbits; on the sexes of young pigeons; on the songs of birds; on pigeons; on the dislike of blue pigeons to other coloured varieties; on the desertion of their mates by female pigeons. Weir, J. Jenner, on the nightingale and blackcap; on the relative sexual maturity of male birds; on female pigeons deserting a feeble mate; on three starlings frequenting the same nest; on the proportion of the sexes in Machetes pugnax and other birds; on the coloration of the Triphaenae; on the rejection of certain caterpillars by birds; on sexual differences of the beak in the goldfinch; on a piping bullfinch; on the object of the nightingale's song; on song-birds; on the pugnacity of male fine-plumaged birds; on the courtship of birds; on the finding of new mates by Peregrine falcons and Kestrels; on the bullfinch and starling; on the cause of birds remaining unpaired; on starlings and parrots living in triplets; on recognition of colour by birds; on hybrid birds; on the selection of a greenfinch by a female canary; on a case of rivalry of female bullfinches; on the maturity of the golden pheasant. Weisbach, Dr., measurement of men of different races; on the greater variability of men than of women; on the relative proportions of the body in the sexes of different races of man. Weismann, Prof., colours of Lycaenae. Welcker, M., on brachycephaly and dolichocephaly; on sexual differences in the skull in man. Wells, Dr., on the immunity of coloured races from certain poisons. Westring, on the stridulation of males of Theridion; on the stridulation of Reduvius personatus; on the stridulation of beetles; on the stridulation of Omaloplia brunnea; on the stridulating organs of the Coleoptera; on sounds produced by Cychrus. Westropp, H.M., on reason in a bear; on the prevalence of certain forms of ornamentation. Westwood, J.O., on the classification of the Hymenoptera; on the Culicidae and Tabanidae; on a Hymenopterous parasite with a sedentary male; on the proportions of the sexes in Lucanus cervus and Siagonium; on the absence of ocelli in female Mutillidae; on the jaws of Ammophila; on the copulation of insects of distinct species; on the male of Crabro cribrarius; on the pugnacity of the male Tipulae; on the stridulation of Pirates stridulus; on the Cicadae; on the stridulating organs of the cricket; on Ephippiger vitium; on Pneumora; on the pugnacity of the Mantides; on Platyblemnus; on difference in the sexes of the Agrionidae; on the pugnacity of the males of a species of Tenthredinae; on the pugnacity of the male stag-beetle; on Bledius taurus and Siagonium; on lamellicorn beetles; on the coloration of Lithosia. Whale, Sperm-, battles of male. Whales, nakedness of. Whately, Arch., language not peculiar to man; on the primitive civilisation of man. Whewell, Prof., on maternal affection. Whiskers, in monkeys. White, F.B., noise produced by Hylophila. White, Gilbert, on the proportion of the sexes in the partridge; on the house-cricket; on the object of the song of birds; on the finding of new mates by white owls; on spring coveys of male partridges. Whiteness, a sexual ornament in some birds; of mammals inhabiting snowy countries. White-throat, aerial love-dance of the male. Whitney, Prof., on the development of language; language not indispensable for thought. Widgeon, pairing with a pintail duck. Widow-bird, polygamous; breeding plumage of the male; female, rejecting the unadorned male. Widows and widowers, mortality of. Wilckens, Dr., on the modification of domestic animals in mountainous regions; on a numerical relation between the hairs and excretory pores in sheep. Wilder, Dr. Burt, on the greater frequency of supernumerary digits in men than in women. Williams, on the marriage-customs of the Fijians. Wilson, Dr., on the conical heads of the natives of North-Western Africa; on the Fijians; on the persistence of the fashion of compressing the skull. Wing-spurs. Wings, differences of, in the two sexes of butterflies and Hymenoptera; play of, in the courtship of birds. Winter, change of colour of mammals in. Witchcraft. Wives, traces of the forcible capture of. Wolf, winter change of the. Wolff, on the variability of the viscera in man. Wollaston, T.V., on Eurygnathus; on musical Curculionidae; on the stridulation of Acalles. Wolves, learning to bark from dogs; hunting in packs. Wolves, black. Wombat, black varieties of the. Women, distinguished from men by male monkeys; preponderance of, in numbers; selection of, for beauty; effects of selection of, in accordance with different standards of beauty; practice of capturing; early betrothals and slavery of; freedom of selection by, in savage tribes. Wonder, manifestations of, by animals. Wonfor, Mr., on sexual peculiarities, in the wings of butterflies. Wood, J., on muscular variations in man; on the greater variability of the muscles in men than in women. Wood, T.W., on the colouring of the orange-tip butterfly; on the habits of the Saturniidae; quarrels of chamaeleons; on the habits of Menura Alberti; on Tetrao cupido; on the display of plumage by male pheasants; on the ocellated spots of the Argus pheasant; on fighting of Menura superba; on the habits of the female cassowary. Woodcock, coloration of the. Woodpecker, selection of a mate by the female. Woodpeckers, tapping of; colours and nidification of the; characters of young. Woolner, Mr., observations on the ear in man. Wormald, Mr., on the coloration of Hypopyra. Wounds, healing of. Wren, young of the. Wright, C.A., on the young of Orocetes and Petrocincla. Wright, Chauncey, great brain-power requisite for language; on correlative acquisition; on the enlargement of the brain in man. Wright, Mr., on the Scotch deer-hound; on sexual preference in dogs; on the rejection of a horse by a mare. Wright, W. von, on the protective plumage of the Ptarmigan. Writing. Wyman, Prof., on the prolongation of the coccyx in the human embryo; on the condition of the great toe in the human embryo; on the occurrence of the supra-condyloid foramen in the humerus of man; on variation in the skulls of the natives of the Sandwich Islands; on the hatching of the eggs in the mouths and branchial cavities of male fishes. Xenarchus, on the Cicadae. Xenophon, selection in mankind advocated by. Xenorhynchus, sexual difference in the colour of the eyes in. Xiphophorus Hellerii, peculiar anal fin of the male. Xylocopa, difference of the sexes in. Yarrel, W., on the habits of the Cyprinidae; on Raia clavata; on the characters of the male salmon during the breeding season; on the characters of the rays; on the gemmeous dragonet; on colours of salmon; on the spawning of the salmon; on the incubation of the Lophobranchii; on rivalry in song-birds; on the trachea of the swan; on the moulting of the Anatidae; on the young of the waders. Yellow fever, immunity of negroes and mulattoes from. Youatt, Mr., on the development of the horns in cattle. Yura-caras, their notions of beauty. Zebra, rejection of an ass by a female; stripes of the. Zebus, humps of. Zigzags, prevalence of, as ornaments. Zincke, Mr., on European emigration to America. Zootoca vivipara, sexual difference in the colour of. Zouteveen, Dr., polydactylism; proportion of sexes at Cape of Good Hope; spiders attracted by music; on sounds produced by fish. Zygaenidae, coloration of the. THE END. 
7234	----	Species and Varieties Their Origin by Mutation Lectures delivered at the University of California By Hugo DeVries Professor of Botany in the University of Amsterdam Edited by Daniel Trembly MacDougal Director Department of Botanical Research Carnegie Institution of Washington Second Edition Corrected and Revised CHICAGO The Open Court Publishing Company LONDON Kegan Paul, Trench, Trubner and Co., Ltd. 1906 - - - - - COPYRIGHT 1904 BY The Open Court Pub. Co. CHICAGO - - - - - THE ORIGIN OF SPECIES The origin of species is a natural phenomenon. LAMARCK The origin of species is an object of inquiry. DARWIN The origin of species is an object of experimental investigation. DeVRIES. - - - - - PREFACE BY THE AUTHOR THE purpose of these lectures is to point out the means and methods by which the origin of species and varieties may become an object for experimental inquiry, in the interest of agricultural and horticultural practice as well as in that of general biologic science. Comparative studies have contributed all the evidence hitherto adduced for the support of the Darwinian theory of descent and given us some general ideas about the main lines of the pedigree of the vegetable kingdom, but the way in which one species originates from another has not been adequately explained. The current belief assumes that species are slowly changed into new types. In contradiction to this conception the theory of mutation assumes that new species and varieties are produced from existing forms by sudden leaps. The parent-type itself remains unchanged throughout this process, and may repeatedly give birth to new forms. These may arise simultaneously and in groups or separately at more or less widely distant periods. The principal features of the theory of mutation have been dealt with at length in my book "Die Mutationstheorie" (Vol. I., 1901, Vol. II., 1903. Leipsic, Veit & Co.), in which I have endeavored to present as completely as possible the detailed evidence obtained from trustworthy historical records, and from my own experimental researches, upon which the theory is based. The University of California invited me to deliver a series of lectures on this subject, at Berkeley, during the [vii] summer of 1904, and these lectures are offered in this form to a public now thoroughly interested in the progress of modern ideas on evolution. Some of my experiments and pedigree-cultures are described here in a manner similar to that used in the "Mutationstheorie," but partly abridged and partly elaborated, in order to give a clear conception of their extent and scope. New experiments and observations have been added, and a wider choice of the material afforded by the more recent current literature has been made in the interest of a clear representation of the leading ideas, leaving the exact and detailed proofs thereof to the students of the larger book. Scientific demonstration is often long and encumbered with difficult points of minor importance. In these lectures I have tried to devote attention to the more important phases of the subject and have avoided the details of lesser interest to the general reader. Considerable care has been bestowed upon the indication of the lacunae in our knowledge of the subject and the methods by which they may be filled. Many interesting observations bearing upon the little known parts of the subject may be made with limited facilities, either in the garden or upon the wild flora. Accuracy and perseverance, and a warm love for Nature's children are here the chief requirements in such investigations. In his admirable treatise on Evolution and Adaptation (New York, Macmillan & Co., 1903), Thomas Hunt Morgan has dealt in a critical manner with many of the speculations upon problems subsidiary to the theory of descent, in so convincing and complete a manner, that I think myself justified in neglecting these questions here. His book gives an accurate survey of them all, and is easily understood by the general reader. In concluding I have to offer my thanks to Dr. D.T. MacDougal and Miss A.M. Vail of the New York Botanical Garden for their painstaking work in the preparation of the manuscript for the press. Dr. MacDougal, by [viii] his publications, has introduced my results to his American colleagues, and moreover by his cultures of the mutative species of the great evening-primrose has contributed additional proof of the validity of my views, which will go far to obviate the difficulties, which are still in the way of a more universal acceptation of the theory of mutation. My work claims to be in full accord with the principles laid down by Darwin, and to give a thorough and sharp analysis of some of the ideas of variability, inheritance, selection, and mutation, which were necessarily vague at his time. It is only just to state, that Darwin established so broad a basis for scientific research upon these subjects, that after half a century many problems of major interest remain to be taken up. The work now demanding our attention is manifestly that of the experimental observation and control of the origin of species. The principal object of these lectures is to secure a more general appreciation of this kind of work. HUGO DE VRIES. Amsterdam, October, 1904. [ix] PREFACE BY THE EDITOR PROFESSOR DE VRIES has rendered an additional service to all naturalists by the preparation of the lectures on mutation published in the present volume. A perusal of the lectures will show that the subject matter of "Die Mutationstheorie" has been presented in a somewhat condensed form, and that the time which has elapsed since the original was prepared has given opportunity for the acquisition of additional facts, and a re-examination of some of the more important conclusions with the result that a notable gain has been made in the treatment of some complicated problems. It is hoped that the appearance of this English version of the theory of mutation will do much to stimulate investigation of the various phases of the subject. This volume, however, is by no means intended to replace, as a work of reference, the larger book with its detailed recital of facts and its comprehensive records, but it may prove a substitute for the use of the general reader. The revision of the lectures has been a task attended with no little pleasure, especially since it has given the editor the opportunity for an advance consideration of some of the more recent results, thus materially facilitating investigations which have been in progress at the New York Botanical Garden for some time. So far as the ground has been covered the researches in question corroborate the conclusions of de Vries in all important particulars. The preparation of the manuscript for the printer has consisted chiefly in the adaptation of oral [xii] discussions and demonstrations to a form suitable for permanent record, together with certain other alterations which have been duly submitted to the author. The original phraseology has been preserved as far as possible. The editor wishes to acknowledge material assistance in this work from Miss A.M. Vail, Librarian of the New York Botanical Garden. D.T. MacDougal. New York Botanical Garden, October, 1904. PREFACE TO THE SECOND EDITION. THE constantly increasing interest in all phases of evolution has made necessary the preparation of a second edition of this book within a few months after the first appeared. The opportunity has been used to eliminate typographical errors, and to make alterations in the form of a few sentences for the sake of clearness and smoothness. The subject matter remains practically unchanged. An explanatory note has been added on page 575 in order to avoid confusion as to the identity of some of the plants which figure prominently in the experimental investigations in Amsterdam and New York. The portrait which forms the frontispiece is a reproduction of a photograph taken by Professor F.E. Lloyd and Dr. W.A. Cannon during the visit of Professor de Vries at the Desert Botanical Laboratory of the Carnegie Institution, at Tucson, Arizona, in June, 1904. D. T. MACDOUGAL. December 15, 1905. CONTENTS A. INTRODUCTION. LECTURE PAGE I. Descent: theories of evolution and methods of investigation. 1 The theory of descent and of natural selection. Evolution and adaptation. Elementary species and varieties. Methods of scientific pedigree-culture. B. ELEMENTARY SPECIES. II. Elementary species in nature. 32 _Viola tricolor_, _Draba verna_, _Primula acaulis_, and other examples. _Euphorbia pecacuanha_. _Prunus maritima_. _Taraxacum_ and _Hieracium_. III. Elementary species of cultivated plants. 63 Beets, apples, pears, clover, flax and coconut. IV. Selection of elementary species. 92 Cereals. Le Couteur. Running out of varieties. Rimpau and Risler, _Avena fatua_. Meadows. Old Egyptian cereals. Selection by the Romans. Shirreff. Hays. C. RETROGRADE VARIETIES. V. Characters of retrograde varieties. 121 Seed varieties of pure, not hybrid origin. Differences from elementary species. Latent characters. Ray-florets of composites. [xiii] Progressive red varieties. Apparent losses. _Xanthium canadense_. Correlative variability. Laciniate leaves and petals. Compound characters. VI. Stability and real atavism. 154 Constancy of retrograde varieties. Atavism in _Ribes sanguineum Albidum_, in conifers, in _Iris pallida_. Seedlings of _Acacia_. Reversion by buds. VII. Ordinary or false atavism. 185 Vicinism or variation under the influence of pollination by neighboring individuals. Vicinism in nurseries. Purifying new and old varieties. A case of running out of corn in Germany. VIII. Latent characters. 216 Leaves of seedlings, adventitious buds, systematic latency and retrogressive evolution. Degressive evolution. Latency of specific and varietal characters in wheat-ear carnation, in the green dahlias, in white campanulas and others. Systematic latency of flower colors. IX. Crossing of species and varieties. 247 Balanced and unbalanced, or species and variety crosses. Constant hybrids of _Oenothera muricata_ and _O. biennis_. _Aegilops_, _Medicago_, brambles and other instances. X. Mendel's law of balanced crosses. 276 Pairs of antagonistic characters, one active and one latent. _Papaver somniferum_. [xiv] _Mephisto Danebrog_. Mendel's laws. Unit-characters. D. EVERSPORTING VARIETIES. XI. Striped flowers. 309 _Antirrhinum majus luteum rubro-striatum_ with pedigree. Striped flowers, fruits and radishes. Double stocks. XII. "Five leaved" clover. 340 Origin of this variety. Periodicity of the anomaly. Pedigree-cultures. Ascidia. XIII. Polycephalic poppies. 369 Permanency and high variability. Sensitive period of the anomaly. Dependency on external conditions. XIV. Monstrosities. 400 Inheritance of monstrosities. Half races and middle races. Hereditary value of atavists. Twisted stems and fasciations. Middle races of tricotyls and syncotyls. Selection by the hereditary percentage among the offspring. XV. Double adaptations. 430 Analogy between double adaptations and anomalous middle races. _Polygonum amphibium_. Alpine plants. _Othonna crassifolia_. Leaves in sunshine and shadow. Giants and dwarfs. Figs and ivy. Leaves of seedlings. E. MUTATIONS. XVI. Origin of the peloric toad-flax. 459 Sudden and frequent origin in the wild state. Origin in the experiment-garden. Law of repeated mutations. Probable origin of other pelories. [xv] XVII. The production of double flowers. 488 Sudden appearance of double flowers in horticulture. Historical evidence. Experimental origin of _Chrysanthemum segetum plenum_. Dependency upon nourishment. Petalody of stamens. XVIII New species of _Oenothera_. 516 Mutations of _Oenothera lamarckiana_ in the wild state near Hilversum. New varieties of _O. laevifolia_, _O. brevistylis_, and _O. nanella_. New elementary species, _O. gigas_, _O. rubrinervis_, _albida_, and _oblonga_. _O. lata_, a pistillate form. Inconstancy of _O. scintillans_. XIX. Experimental pedigree-cultures. 547 Pedigree of the mutative products of _Oenothera lamarckiana_ in the Botanical Garden at Amsterdam. Laws of mutability. Sudden and repeated leaps from an unchanging main strain. Constancy of the new forms. Mutations in all directions. XX. Origin of wild species and varieties. 576 Problems to solve. _Capsella heegeri_. _Oenothera biennis cruciata_. _Epilobium hirsutum cruciatum_. _Hibiscus Moscheutos_. Purple beech. Monophyllous strawberries. Chances of success with new mutations. XXI. Mutations in horticulture. 604 _Chelidonium majus lacinatum_. Dwarf and spineless varieties. Laciniate leaves. Monophyllous and broom-like varieties. [xvi] Purple leaves. _Celosia_. Italian poplar. Cactus dahlia. Mutative origin of _Dahlia fistulosa_, and _Geranium praetense_ in the experiment-garden. XXII. Systematic atavism. 630 Reappearance of ancestral characters. _Primula acaulis umbellata_. Bracts of crucifers. _Zea Mays cryptosperma_. Equisetum, _Dipsacus sylvestris torsus_. Tomatoes. XXIII. Taxonomic anomalies. 658 Specific characters occurring in other cases as casual anomalies. _Papaver bracteatum monopetalum_. _Desmodium gyrans_ and monophyllous varieties. Peltate leaves and ascidia. Flowers on leaves. Leaves. _Hordeum trifurcatum_. XXIV. Hypothesis of periodical mutations. 686 Discovering mutable strains. Periods of mutability and constancy. Periods of mutations. Genealogical trees. Limited life-time of the organic kingdom. F. FLUCTUATIONS. XXV. General laws of fluctuations. 715 Fluctuating variability. Quetelet's law. Individual and partial fluctuations. Linear variability. Influence of nutrition. Periodicity curves. XXVI. Asexual multiplication of extremes. 742 Selection between species and intra-specific selection. Excluding individual [xvii] embryonic variability. Sugar-canes. Flowering cannas. Double lilacs. Other instances. Burbank's method of selection. XXVII. Inconstancy of improved races 770 Larger variability in the case of propagation by seed, progression and regression after a single selection, and after repeated selections. Selection experiments with corn. Advantages and effect of repeated selection. XXVIII. Artificial and natural selection. 798 Conclusions. Specific and intra-specific selection. Natural selection in the field. Acclimatization. Improvement-selection of sugar-beets by various methods. Rye. Hereditary percentage and centgener power as marks by which intraspecific selection may be guided. Index 827 [1] A. INTRODUCTION LECTURE I DESCENT: THEORIES OF EVOLUTION AND METHODS OF INVESTIGATION Newton convinced his contemporaries that natural laws rule the whole universe. Lyell showed, by his principle of slow and gradual evolution, that natural laws have reigned since the beginning of time. To Darwin we owe the almost universal acceptance of the theory of descent. This doctrine is one of the most noted landmarks in the advance of science. It teaches the validity of natural laws of life in its broadest sense, and crowns the philosophy founded by Newton and Lyell. Lamarck proposed the hypothesis of a common origin of all living beings and this ingenious and thoroughly philosophical conception was warmly welcomed by his partisans, but was not widely accepted owing to lack of supporting evidence. To Darwin was reserved the task of [2] bringing the theory of common descent to its present high rank in scientific and social philosophy. Two main features in his work have contributed to this early and unexpected victory. One of them is the almost unlimited amount of comparative evidence, the other is his demonstration of the possibility of a physiological explanation of the process of descent itself. The universal belief in the independent creation of living organisms was revised by Linnaeus and was put upon a new foundation. Before him the genera were supposed to be created, the species and minor forms having arisen from them through the agency of external conditions. In his first book Linnaeus adhered to this belief, but later changed his mind and maintained the principle of the separate creation of species. The weight of his authority soon brought this conception to universal acceptance, and up to the present time the prevailing conception of a species has been chiefly based on the definition given by Linnaeus. His species comprised subspecies and varieties, which were in their turn, supposed to have evolved from species by the common method. Darwin tried to show that the links which bind species to genera are of the same nature as those which determine the relationship of [3] subspecies and varieties. If an origin by natural laws is conceded for the latter, it must on this ground be granted for the first also. In this discussion he simply returned to the pre-Linnean attitude. But his material was such as to allow him to go one step further, and this step was an important and decisive one. He showed that the relation between the various genera of a family does not exhibit any features of a nature other than that between the species of a genus. What has been conceded for the one must needs be accepted for the other. The same holds good for the large groups. The conviction of the common origin of closely allied forms necessarily leads to the conception of a similar descent even in remote relationships. The origin of subspecies and varieties as found in nature was not proved, but only generally recognized as evident. A broader knowledge has brought about the same state of opinion for greater groups of relationships. Systematic affinities find their one possible explanation by the aid of this principle; without it, all similarity is only apparent and accidental. Geographic and paleontologic facts, brought together by Darwin and others on a previously unequalled scale, point clearly in the same direction. The vast amount of evidence of all [4] comparative sciences compels us to accept the idea. To deny it, is to give up all opportunity of conceiving Nature in her true form. The general features of the theory of descent are now accepted as the basis of all biological science. Half a century of discussion and investigation has cleared up the minor points and brought out an abundance of facts; but they have not changed the principle. Descent with modification is now universally accepted as the chief law of nature in the organic world. In honor of him, who with unsurpassed genius, and by unlimited labor has made it the basis of modern thought, this law is called the "Darwinian theory of descent." Darwin's second contribution to this attainment was his proof of the possibility of a physiological explanation of the process of descent itself. Of this possibility he fully convinced his contemporaries, but in indicating the particular means by which the change of species has been brought about, he has not succeeded in securing universal acceptation. Quite on the contrary, objections have been raised from the very outset, and with such force as to compel Darwin himself to change his views in his later writings. This however, was of no avail, and objections and criticisms have since steadily accumulated. Physiologic facts concerning the origin of [5] species in nature were unknown in the time of Darwin. It was a happy idea to choose the experience of the breeders in the production of new varieties, as a basis on which to build an explanation of the processes of nature. In my opinion Darwin was quite right, and he has succeeded in giving the desired proof. But the basis was a frail one, and would not stand too close an examination. Of this Darwin was always well aware. He has been prudent to the utmost, leaving many points undecided, and among them especially the range of validity of his several arguments. Unfortunately this prudence has not been adopted by his followers. Without sufficient warrant they have laid stress on one phase of the problem, quite overlooking the others. Wallace has even gone so far in his zeal and ardent veneration for Darwin, as to describe as Darwinism some things, which in my opinion, had never been a part of Darwin's conceptions. The experience of the breeders was quite inadequate to the use which Darwin made of it. It was neither scientific, nor critically accurate. Laws of variation were barely conjectured; the different types of variability were only imperfectly distinguished. The breeders' conception was fairly sufficient for practical purposes, but science needed a clear understanding of the [6] factors in the general process of variation. Repeatedly Darwin tried to formulate these causes, but the evidence available did not meet his requirements. Quetelet's law of variation had not yet been published. Mendel's claim of hereditary units for the explanation of certain laws of hybrids discovered by him, was not yet made. The clear distinction between spontaneous and sudden changes, as compared with the ever-present fluctuating variations, is only of late coming into recognition by agriculturists. Innumerable minor points which go to elucidate the breeders' experience, and with which we are now quite familiar, were unknown in Darwin's time. No wonder that he made mistakes, and laid stress on modes of descent, which have since been proved to be of minor importance or even of doubtful validity. Notwithstanding all these apparently unsurmountable difficulties, Darwin discovered the great principle which rules the evolution of organisms. It is the principle of natural selection. It is the sifting out of all organisms of minor worth through the struggle for life. It is only a sieve, and not a force of nature, not a direct cause of improvement, as many of Darwin's adversaries, and unfortunately many of his followers also, have so often asserted. It is [7] only a sieve, which decides what is to live, and what is to die. But evolutionary lines are of great length, and the evolution of a flower, or of an insectivorous plant is a way with many sidepaths. It is the sieve that keeps evolution on the main line, killing all, or nearly all that try to go in other directions. By this means natural selection is the one directing cause of the broad lines of evolution. Of course, with the single steps of evolution it has nothing to do. Only after the step has been taken, the sieve acts, eliminating the unfit. The problem, as to the manner in which the individual steps are brought about, is quite another side of the question. On this point Darwin has recognized two possibilities. One means of change lies in the sudden and spontaneous production of new forms from the old stock. The other method is the gradual accumulation of those always present and ever fluctuating variations which are indicated by the common assertion that no two individuals of a given race are exactly alike. The first changes are what we now call "mutations," the second are designated as "individual variations," or as this term is often used in another sense, as "fluctuations." Darwin recognized both lines of evolution; Wallace disregarded the sudden changes and proposed fluctuations [8] as the exclusive factor. Of late, however, this point of view has been abandoned by many investigators, especially in America. The actual occurrence of mutations is recognized, and the battle rages about the question, as to whether they are be regarded as the principal means of evolution, or whether slow and gradual changes have not also played a large and important part. The defenders of the theory of evolution by slow accumulation of slight fluctuations are divided into two camps. One group is called the Neo-Lamarckians; they assume a direct modifying agency of the environment, producing a corresponding and useful change in the organization. The other group call themselves Darwinians or selectionists, but to my mind with no other right beyond the arbitrary restriction of the Darwinian principles by Wallace. They assume fluctuating variations in all directions and leave the choice between them to the sieve of natural selection. Of course we are far from a decision between these views, on the sole ground of the facts as known at present. Mutations under observation are as yet very rare; enough to indicate the possible and most probable ways, but no more. On the other hand the accumulation of fluctuations does not transgress relatively narrow [9] limits as far as the present methods of selection go. But the question remains to be solved, whether our methods are truly the right ones, and whether by the use of new principles, new results might not cause the balance of opinion to favor the opposite side. Of late, a thorough and detailed discussion of the opposing views has been given by Morgan in his valuable book on evolution and adaptation. He has subjected all the proposed theories to a severe criticism both on the ground of facts and on that of their innate possibility and logical value. He decides in favor of the mutation theory. His arguments are incisive and complete and wholly adapted to the comprehension of all intelligent readers, so that his book relieves me entirely of the necessity of discussing these general questions, as it could not be done in a better or in a clearer way. I intend to give a review of the facts obtained from plants which go to prove the assertion, that species and varieties have originated by mutation, and are, at present, not known to originate in any other way. This review consists of two parts. One is a critical survey of the facts of agricultural and horticultural breeding, as they have accumulated since the time of Darwin. This body of evidence is to be combined with some corresponding experiments [10] concerning the real nature of species in the wild state. The other part rests on my own observations and experiments, made in the botanical garden of the University of Amsterdam. For many years past I have tried to elucidate the hereditary conditions of species and varieties, and the occasional occurrence of mutations, that suddenly produce new forms. The present discussion has a double purpose. On one side it will give the justification of the theory of mutations, as derived from the facts now at hand. On the other hand it will point out the deficiencies of available evidence, and indicate the ways by which the lacunae may gradually be filled. Experimental work on heredity does not require vast installments or costly laboratory equipment. It demands chiefly assiduity and exactitude. Any one who has these two qualities, and who has a small garden at his disposal is requested to take part in this line of investigation. In order to observe directly the birth of new forms it is necessary, in the first place, to be fully clear concerning the question as to what forms are to be expected to arise from others, and before proceeding to a demonstration of the origin of species, it is pertinent to raise the question as to what constitutes a species. Species is a word, which always has had a [11] double meaning. One is the systematic species, which is the unit of our system. But these units are by no means indivisible. Long ago Linnaeus knew them to be compound in a great number of instances, and increasing knowledge has shown that the same rule prevails in other instances. Today the vast majority of the old systematic species are known to consist of minor units. These minor entities are called varieties in systematic works. However, there are many objections to this usage. First, the term variety is applied in horticulture and agriculture to things so widely divergent as to convey no clear idea at all. Secondly, the subdivisions of species are by no means all of the same nature, and the systematic varieties include units the real value of which is widely different in different cases. Some of these varieties are in reality as good as species, and have been "elevated," as it is called by some writers, to this rank. This conception of the elementary species would be quite justifiable, and would at once get rid of all difficulties, were it not for one practical obstacle. The number of the species in all genera would be doubled and tripled, and as these numbers are already cumbersome in many cases, the distinction of the native species of any given country would lose most of its charm and interest. [12] In order to meet this difficulty we must recognize two sorts of species. The systematic species are the practical units of the systematists and florists, and all friends of wild nature should do their utmost to preserve them as Linnaeus has proposed them. These units however, are not really existing entities; they have as little claim to be regarded as such as genera and families. The real units are the elementary species; their limits often apparently overlap and can only in rare cases be determined on the sole ground of field observations. Pedigree-culture is the method required and any form which remains constant and distinct from its allies in the garden is to be considered as an elementary species. In the following lectures we shall consider this point at length, to show the compound nature of systematic species in wild and in cultivated plants. In both cases, the principle is becoming of great importance, and many papers published recently indicate its almost universal acceptation. Among the systematic subdivisions of species, not all have the same claim to the title of elementary species. In the first place the cases in which the differences may occur between parts of the same individual are to be excluded. Dividing an alpine plant into two halves and [13] planting one in a garden, varietal differences at once arise and are often designated in systematic works under different varietal names. Secondly all individual differences which are of a fluctuating nature are to be combined into a group. But with these we shall deal later. Apart from these minor points the subdivisions of the systematic species exhibit two widely different features. I will now try to make this clear in a few words, but will return in another lecture to a fuller discussion of this most interesting contrast. Linnaeus himself knew that in some cases all subdivisions of a species are of equal rank, together constituting the group called species. No one of them outranks the others; it is not a species with varieties, but a group, consisting only of varieties. A closer inquiry into the cases treated in this manner by the great master of systematic science, shows that here his varieties were exactly what we now call elementary species. In other cases the varieties are of a derivative nature. The species constitutes a type that is pure in a race which ordinarily is still growing somewhere, though in some cases it may have died out. From this type the varieties are derived, and the way of this derivation is usually quite manifest to the botanist. It is ordinarily [14] by the disappearance of some superficial character that a variety is distinguished from its species, as by the lack of color in the flowers, of hairs on stems and foliage, of the spines and thorns, &c. Such varieties are, strictly speaking, not to be treated in the same way as elementary species, though they often are. We shall designate them by the term of "retrograde varieties," which clearly indicates the nature of their relationship to the species from which they are assumed to have sprung. In order to lay more stress on the contrast between elementary species and retrograde varieties, it should be stated at once, that the first are considered to have originated from their parent-form in a progressive way. They have succeeded in attaining something quite new for themselves, while retrograde varieties have only thrown off some peculiarity, previously acquired by their ancestors. The whole vegetable kingdom exhibits a constant struggle between progression and retrogression. Of course, the great lines of the general pedigree are due to progression, many single steps in this direction leading together to the great superiority of the flowering plants over their cryptogamous ancestors. But progression is nearly always accompanied by retrogression in the principal lines of evolution, [15] as well as in the collateral branches of the genealogical tree. Sometimes it prevails, and the monocotyledons are obviously a reduced branch of the primitive dicotyledons. In orchids and aroids, in grasses and sedges, reduction plays a most important part, leaving its traces on the flowers as well as on the embryo of the seed. Many instances could be given to prove that progression and retrogression are the two main principles of evolution at large. Hence the conclusion, that our analysis must dissect the complicated phenomena of evolution so far as to show the separate functions of these two contrasting principles. Hundreds of steps were needed to evolve the family of the orchids, but the experimenter must take the single steps for the object of his inquiry. He finds that some are progressive and others retrogressive and so his investigation falls under two heads, the origin of progressive characters, and the subsequent loss of the same. Progressive steps are the marks of elementary species, while retrograde varieties are distinguished by apparent losses. They have equal claim to our interest and our study. As already stated I propose to deal first with the elementary species and afterwards with the retrograde varieties. I shall try to depict them to you in the first place as they are seen in [16] nature and in culture, leaving the question of their origin to a subsequent experimental treatment. The question of the experimental origin of new species and varieties has to be taken up from two widely separated starting points. This may be inferred from what we have already seen concerning the two opposing theories, derived and isolated from Darwin's original broad conception. One of them considers mutations as the origin of new forms, while the other assumes fluctuations to be the source of all evolution. As mentioned above, my own experience has led me to accept the first view. Therefore I shall have to show that mutations do yield new and constant forms, while fluctuations are not adequate to do so. Retrograde varieties and elementary species may both be seen to be produced by sudden mutations. Varieties have often been observed to appear at once and quite unexpectedly in horticulture and agriculture, and a survey of these historical facts will be the subject of one of my lectures. In some instances I have succeeded in repeating these observations in my garden under the strict conditions of a scientific experiment, and these instances teach us the real nature of the process of mutation in all its visible features. New elementary [17] species are far more rare, but I have discovered in the great evening-primrose, or _Oenothera lamarckiana_ a strain which is producing them yearly in the wild state as well as in my garden. These observations and pedigree-experiments will be dealt with at due length in subsequent lectures. Having proved the existence and importance of mutations, it remains to inquire how far the improvements may go which are due only to fluctuating variability. As the term indicates, this variability is fluctuating to and fro, oscillating around an average type. It never fails nor does it, under ordinary circumstances, depart far from the fixed average. But the deviation may be enlarged by a choice of extremes. In sowing their seed, the average of the strain is seen to be changed, and in repeating the experiment the change may be considerable. It is not clear, whether theoretically by such an accumulation, deviations might be reached which could not be attained at once in a single sowing. This question is hardly susceptible of an experimental answer, as it would require such an enormous amount of seed from a few mother plants as can scarcely ever be produced. The whole character of the fluctuations shows them to be of an opposite nature, contrasting [18] manifestly with specific and varietal characters. By this method they may be proved to be inadequate ever to make a single step along the great lines of evolution, in regard to progressive as well as to retrograde development. First of all fluctuations are linear, amplifying or lessening the existing qualities, but not really changing their nature. They are not observed to produce anything quite new, and evolution of course, is not restricted to the increase of the already existing peculiarities, but depends chiefly on the continuous addition of new characters to the stock. Fluctuations always oscillate around an average, and if removed from this for some time, they show a tendency to return to it. This tendency, called retrogression, has never been observed to fail, as it should, in order to free the new strain from the links with the average, while new species and new varieties are seen to be quite free from their ancestors and not linked to them by intermediates. The last few lectures will be devoted to questions concerning the great problem of the analogy between natural and artificial selection. As already stated, Darwin made this analogy the foundation stone of his theory of descent, and he met with the severest objections and criticisms precisely on this point. But I hope to [19] show that he was quite right, and that the cause of the divergence of opinions is due simply to the very incomplete state of knowledge concerning both processes. If both are critically analyzed they may be seen to comprise the same factors, and further discussion may be limited to the appreciation of the part which each of them has played in nature and among cultivated plants. Both natural and artificial selection are partly specific, and partly intra-specific or individual. Nature of course, and intelligent men first chose the best elementary species from among the swarms. In cultivation this is the process of variety-testing. In nature it is the survival of the fittest species, or, as Morgan designates it, the survival of species in the struggle for existence. The species are not changed by this struggle, they are only weighed against each other, the weak being thrown aside. Within the chosen elementary species there is also a struggle. It is obvious, that the fluctuating variability adapts some to the given circumstances, while it lessens the chances of others. A choice results, and this choice is what is often exclusively called selection, either natural or artificial. In cultivation it produces the improved and the local races; in nature little is known about improvement in this way, but [19] local adaptations with slight changes of the average character in separate localities, seem to be of quite normal occurrence. A new method of individual selection has been used in recent years in America, especially by W.M. Hays. It consists in judging the hereditary worth of a plant by the average condition of its offspring, instead of by its own visible characters. If this determination of the "centgener power," as Hays calls it, should prove to be the true principle of selection, then indeed the analogy between natural and artificial selection would lose a large part of its importance. We will reserve this question for the last lecture, as it pertains more to the future, than to our present stock of knowledge. Something should be said here concerning hybrids and hybridism. This problem has of late reached such large proportions that it cannot be dealt with adequately in a short survey of the phenomena of heredity in general. It requires a separate treatment. For this reason I shall limit myself to a single phase of the problem, which seems to be indispensable for a true and at the same time easy distinction between elementary species and retrograde varieties. According to accepted terminology, some crosses are to be considered as unsymmetrical, while others are symmetrical. The first are one-sided, [21] some peculiarity being found in one of the parents and lacking in the other. The second are balanced, as all the characters are present in both parents, but are found in a different condition. Active in one of them, they are concealed or inactive in the other. Hence pairs of contrasting units result, while in unbalanced crosses no pairing of the particular character under consideration is possible. This leads to the principal difference between species and varieties, and to an experimental method of deciding between them in difficult and doubtful cases. Having thus indicated the general outlines of the subjects I shall deal with, something now may be said as to methods of investigation. There are two points in which scientific investigation differs from ordinary pedigree-culture in practice. First the isolation of the individuals and the study of individual inheritance, instead of averages. Next comes the task of keeping records. Every individual must be entered, its ancestry must be known as completely as possible, and all its relations must be noted in such a form, that the most complete reference is always possible. Mutations may come unexpectedly, and when once arisen, their parents and grand-parents should be known. Records must be available which will allow of a most complete knowledge of the whole ancestral [22] line. This, and approximately this only, is the essential difference between experimental and accidental observation. Mutations are occurring from time to time in the wild state as well as in horticulture and agriculture. A selection of the most interesting instances will be given later. But in all such cases the experimental proof is wanting. The observations as a rule, only began when the mutation had made its appearance. A more or less vague remembrance about the previous state of the plants in question might be available, though even this is generally absent. But on doubtful points, concerning possible crosses or possible introduction of foreign strains, mere recollection is insufficient. The fact of the mutation may be very probable, but the full proof is, of course, wanting. Such is the case with the mutative origin of _Xanthium commune_ Wootoni from New Mexico and of _Oenothera biennis cruciata_ from Holland. The same doubt exists as to the origin of the _Capsella heegeri_ of Solms-Laubach, and of the oldest recorded mutation, that of _Chelidonium laciniatum_ in Heidelberg about 1600. First, we have doubts about the fact itself. These, however, gradually lose their importance in the increasing accumulation of evidence. Secondly, the impossibility of a closer [23] inquiry into the real nature of the change. For experimental purposes a single mutation does not suffice; it must be studied repeatedly, and be produced more or less arbitrarily, according to the nature of the problems to be solved. And in order to do this, it is evidently not enough to have in hand the mutated individual, but it is indispensable to have also the mutable parents, or the mutable strain from which it sprang. All conditions previous to the mutation are to be considered as of far higher importance than all those subsequent to it. Now mutations come unexpectedly, and if the ancestry of an accidental mutation is to be known, it is of course necessary to keep accounts of all the strains cultivated. It is evident that the required knowledge concerning the ancestry of a supposed mutation, must necessarily nearly all be acquired from the plants in the experimental garden. Obviously this rule is as simple in theory, as it is difficult to carry out in practice. First of all comes the book-keeping. The parents, grandparents and previous ancestors must be known individually. Accounts of them must be kept under two headings. A full description of their individual character and peculiarities must always be available on the one hand, and on the other, all facts concerning their hereditary [24] qualities. These are to be deduced from the composition of the progeny, and in order to obtain complete evidence on this point, two successive generations are often required. The investigation must ascertain the average condition of this offspring and the occurrence of any deviating specimens, and for both purposes it is necessary to cultivate them in relatively large numbers. It is obvious that, properly speaking, the whole family of a mutated individual, including all its nearer and more remote relatives, should be known and recorded. Hence pedigree-book-keeping must become the general rule. Subordinate to this are two further points, which should likewise be stated here. One pertains to the pure or hybrid nature of the original strain, and the other to the life-conditions and all other external influences. It is manifest that a complete understanding of a mutation depends upon full information upon these points. All experiments must have a beginning. The starting-point may be a single individual, or a small group of plants, or a lot of seeds. In many cases the whole previous history is obscure, but sometimes a little historical evidence is at hand. Often it is evident that the initial material belongs to a pure species, but with respect to the question of elementary species it is [25] not rarely open to doubt. Large numbers of hybrid plants and hybrid races are in existence, concerning the origin of which it is impossible to decide. It is impossible in many instances to ascertain whether they are of hybrid or of pure origin. Often there is only one way of determining the matter; it is to guess at the probable parents in case of a cross and to repeat the cross. This is a point which always requires great care in the interpretation of unusual facts. Three cases are to be distinguished as to heredity. Many plants are so constituted as to be fertilized with their own pollen. In this case the visits of insects have simply to be excluded, which may be done by covering plants with iron gauze or with bags of prepared paper. Sometimes they fertilize themselves without any aid, as for instance, the common evening-primrose; in other cases the pollen has to be placed on the stigma artificially, as with Lamarck's evening-primrose and its derivatives. Other plants need cross-fertilization in order to produce a normal yield of seeds. Here two individuals have always to be combined, and the pedigree becomes a more complicated one. Such is the case with the toad-flax, which is nearly sterile with its own pollen. But even in these cases the visits of insects bringing pollen [26] from other plants, must be carefully excluded. A special lecture will be devoted to this very interesting source of impurity and of uncertainty in ordinary cultures. Of course, crosses may lie in the proposed line of work, and this is the third point to be alluded to. They must be surrounded with the same careful isolation and protection against bees, as any other fertilizations. And not only the seed-parent, but also the pollen must be kept pure from all possible foreign admixtures. A pure and accurately recorded ancestry is thus to be considered as the most important condition of success in experimental plant breeding. Next to this comes the gathering of the seeds of each individual separately. Fifty or sixty, and often more, bags of seeds are by no means uncommon for a single experiment, and in ordinary years the harvest of my garden is preserved in over a thousand separate lots. Complying with these conditions, the origin of species may be seen as easily as any other phenomenon. It is only necessary to have a plant in a mutable condition. Not all species are in such a state at present, and therefore I have begun by ascertaining which were stable and which were not. These attempts, of course, had to be made in the experimental garden, and large quantities of seed had to be procured and [27] sown. Cultivated plants of course, had only a small chance to exhibit new qualities, as they have been so strictly controlled during so many years. Moreover their purity of origin is in many cases doubtful. Among wild plants only those could be expected to reward the investigator which were of easy cultivation. For this reason I have limited myself to the trial of wild plants of Holland, and have had the good fortune to find among them at least one species in a state of mutability. It was not really a native plant, but one that had been introduced from America and belongs to an American genus. I refer to the great evening-primrose or the evening-primrose of Lamarck. A strain of this beautiful species is growing in an abandoned field in the vicinity of Hilversum, at a short distance from Amsterdam. Here it has escaped from a park and multiplied. In doing so it has produced and is still producing quite a number of new types, some of which may be considered as retrograde varieties, while others evidently are of the nature of progressive elementary species. This interesting plant has afforded me the means of observing directly how new species originate, and of studying the laws of these changes. My researches have followed a double line of inquiry. On one side, I have limited [28] myself to direct field observations, and to tests of seed, collected from the wild plants in their native locality. Obviously the mutations are decided within the seed, and the culture of young plants from them had no other aim than that of ascertaining what had occurred in the field. And then the many chances of destruction that threaten young plants in a wild state, could be avoided in the garden, where environmental factors can be controlled. My second line of inquiry was an experimental repetition of the phenomena which were only partly discerned at the native locality. It was not my aim to intrude into the process, nor to try to bring out new features. My only object was to submit to the precepts just given concerning pure treatment, individual seed gathering, exclusion of crosses and accurate recording of all the facts. The result has been a pedigree which now permits of stating the relation between all the descendants of my original introduced plant. This pedigree at once exhibits the laws followed by the mutating species. The main fact is, that it does not change itself gradually, but remains unaffected during all succeeding generations. It only throws off new forms, which are sharply contrasted with the parent, and which are from the very beginning as perfect and as constant, as narrowly [29] defined and as pure of type as might be expected of any species. These new species are not produced once or in single individuals, but yearly and in large numbers. The whole phenomenon conveys the idea of a close group of mutations, all belonging to one single condition of mutability. Of course this mutable state must have had a beginning, as it must sometime come to an end. It is to be considered as a period within the life-time of the species and probably it is only a small part of it. The detailed description of this experiment, however, I must delay to a subsequent lecture, but I may be allowed to state, that the discovery of this period of mutability is of a definite theoretical importance. One of the greatest objections to the Darwinian theory of descent arose from the length of time it would require, if all evolution was to be explained on the theory of slow and nearly invisible changes. This difficulty is at once met and fully surmounted by the hypothesis of periodical but sudden and quite noticeable steps. This assumption requires only a limited number of mutative periods, which might well occur within the time allowed by physicists and geologists for the existence of animal and vegetable life on the earth. [30] Summing up the main points of these introductory remarks, I propose to deal with the subjects mentioned above at some length, devoting to each of them, if possible at least an entire lecture. The decisive facts and discussions upon which the conclusions are based will be given in every case. Likewise I hope to point out the weak places and the lacunae in our present knowledge, and to show the way in which each of you may try to contribute his part towards the advancement of science in this subject. Lastly I shall try to prove that sudden mutation is the normal way in which nature produces new species and new varieties. These mutations are more readily accessible to observation and experiment than the slow and gradual changes surmised by Wallace and his followers, which are entirely beyond our present and future experience. The theory of mutations is a starting-point for direct investigation, while the general belief in slow changes has held back science from such investigations during half a century. Coming now to the subdivisions and headings under which my material is to be presented, I propose describing first the real nature of the elementary species and retrograde varieties, both in normal form and in hybridizations. A discussion of other types of varieties, including [31] monstrosities will complete the general plan. The second subdivision will deal with the origin of species and varieties as taught by experiment and observation, treating separately the sudden variations which to my mind do produce new forms, and subsequently the fluctuations which I hold to be not adequate to this purpose. [32] B. ELEMENTARY SPECIES LECTURE II ELEMENTARY SPECIES IN NATURE What are species? Species are considered as the true units of nature by the vast majority of biologists. They have gained this high rank in our estimation principally through the influence of Linnaeus. They have supplanted the genera which were the accepted units before Linnaeus. They are now to be replaced in their turn, by smaller types, for reasons which do not rest upon comparative studies but upon direct experimental evidence. Biological studies and practical interests alike make new demands upon systematic botany. Species are not only the subject-material of herbaria and collections, but they are living entities, and their life-history and life-conditions command a gradually increasing interest. One phase of the question is to determine the easiest manner to deal with the collected forms of a country, and another feature is the problem [33] as to what groups are real units and will remain constant and unchanged through all the years of our observations. Before Linnaeus, the genera were the real units of the system. De Candolle pointed out that the old common names of plants, such as roses and clover, poplars and oaks, nearly all refer to genera. The type of the clovers is rich in color, and the shape of the flower-heads and the single flowers escape ordinary observation; but notwithstanding this, clovers are easily recognized, even if new types come to hand. White and red clovers and many other species are distinguished simply by adjectives, the generic name remaining the same for all. Tournefort, who lived in the second half of the 17th century (1656-1708), is generally considered as the author of genera in systematic botany. He adopted, what was at that time the general conception and applied it throughout the vegetable kingdom. He grouped the new and the rare and the previously overlooked forms in the same manner in which the more conspicuous plants were already arranged by universal consent. Species were distinguished by minor marks and often indicated by short descriptions, but they were considered of secondary importance. Based on the idea of a direct creation of all [34] living beings, the genera were then accepted as the created forms. They were therefore regarded as the real existing types, and it was generally surmised that species and varieties owed their origin to subsequent changes under the influence of external conditions. Even Linnaeus agreed with this view in his first treatises and in his "Philosophical Botany" he still kept to the idea that all genera had been created at once with the beginning of life. Afterwards Linnaeus changed his opinion on this important point, and adopted species as the units of the system. He declared them to be the created forms, and by this decree, at once reduced the genera to the rank of artificial groups. Linnaeus was well aware that this conception was wholly arbitrary, and that even the species are not real indivisible entities. But he simply forbade the study of lesser subdivisions. At his time he was quite justified in doing so, because the first task of the systematic botanists was the clearing up of the chaos of forms and the bringing of them into connection with their real allies. Linnaeus himself designated the subdivisions of the species as varieties, but in doing so he followed two clearly distinct principles. In some cases his species were real plants, and the varieties seemed to be derived from them by [35] some simple changes. They were subordinated to the parent-species. In other cases his species were groups of lesser forms of equal value, and it was not possible to discern which was the primary and which were the derivatives. These two methods of subdivision seem in the main, and notwithstanding their relatively imperfect application in many single examples, to correspond with two really distinct cases. The derivative varieties are distinguished from the parent-species by some single, but striking mark, and often this attribute manifests itself as the loss of some apparent quality. The loss of spines and of hairs and the loss of blue and red flower-colors are the most notorious, but in rarer cases many single peculiarities may disappear, thereby constituting a variety. This relation of varieties to the parent-species is gradually increasing in importance in the estimation of botanists, sharply contrasting with those cases, in which such dependency is not to be met with. If among the subdivisions of a species, no single one can be pointed out as playing a primary part, and the others can not be traced back to it, the relation between these lesser units is of course of another character. They are to be considered of equal importance. They are distinguished from each other by more than [36] one character, often by slight differences in nearly all their organs and qualities. Such forms have come to be designated as "elementary species." They are only varieties in a broad and vague systematic significance of the word, not in the sense accorded to this term in horticultural usage, nor in a sharper and more scientific conception. Genera and species are, at the present time, for a large part artificial, or stated more correctly, conventional groups. Every systematist is free to delimit them in a wider or in a narrower sense, according to his judgment. The greater authorities have as a rule preferred larger genera, others of late have elevated innumerable subgenera to the rank of genera. This would work no real harm, if unfortunately, the names of the plants had not to be changed each time, according to current ideas concerning genera. Quite the same inconstancy is observed with species. In the Handbook of the British Flora, Bentham and Hooker describe the forms of brambles under 5 species, while Babington in his Manual of British Botany makes 45 species out of the same material. So also in other cases. For instance, the willows which have 13 species in one and 31 species in the other of these manuals, and the hawkweeds for which the figures are 7 and 32 [37] respectively. Other authors have made still greater numbers of species in the same groups. It is very difficult to estimate systematic differences on the ground of comparative studies alone. All sorts of variability occur, and no individual or small group of specimens can really be considered as a reliable representative of the supposed type. Many original diagnoses of new species have been founded on divergent specimens and of course, the type can afterwards neither be derived from this individual, nor from the diagnosis given. This chaotic state of things has brought some botanists to the conviction that even in systematic studies only direct experimental evidence can be relied upon. This conception has induced them to test the constancy of species and varieties, and to admit as real units only such groups of individuals as prove to be uniform and constant throughout succeeding generations. The late Alexis Jordan, of Lyons in France, made extensive cultures in this direction. In doing so, he discovered that systematic species, as a rule, comprise some lesser forms, which often cannot easily be distinguished when grown in different regions, or by comparing dried material. This fact was, of course, most distasteful to the systematists of his time and even for a long period afterwards [38] they attempted to discredit it. Milde and many others have opposed these new ideas with some temporary success. Only of late has the school of Jordan received due recognition, after Thuret, de Bary, Rosen and others tested its practices and openly pronounced for them. Of late Wittrock of Sweden has joined them, making extensive experimental studies concerning the real units of some of the larger species of his country. From the evidence given by these eminent authorities, we may conclude that systematic species, as they are accepted nowadays, are as a rule compound groups. Sometimes they consist of two or three, or a few elementary types, but in other cases they comprise twenty, or fifty, or even hundreds of constant and well differentiated forms. The inner constitution of these groups is however, not at all the same in all cases. This will be seen by the description of some of the more interesting of them. The European heartsease, from which our garden-pansies have been chiefly derived, will serve as an example. The garden-pansies are a hybrid race, won by crossing the _Viola tricolor_ with the large flowered and bright yellow _V. lutea_. They combine, as everyone knows, in their wide range of [39] varieties, the attributes of the latter with the peculiarities of the former species. Besides the _lutea_, there are some other species, nearly allied to tricolor, as for instance, _cornuta_, _calcarata_, and _altaica_, which are combined with it under the head of _Melanium_ as a subgenus, and which together constitute a systematic unity of undoubted value, but ranging between the common conceptions of genus and species. These forms are so nearly allied to the heartsease that they have of late been made use of in crosses, in order to widen the range of variability of garden-pansies. _Viola tricolor_ is a common European weed. It is widely dispersed and very abundant, growing in many localities in large numbers. It is an annual and ripens its seeds freely, and if opportunity is afforded, it multiplies rapidly. _Viola tricolor_ has three subspecies, which have been elevated to the rank of species by some authors, and which may here be called, for brevity's sake, by their binary names. One is the typical _V. tricolor_, with broad flowers, variously colored and veined with yellow, purple and white. It occurs in waste places on sandy soil. The second is called _V. arvensis_ or the field-pansy; it has small inconspicuous flowers, with pale-yellowish petals which are shorter than the sepals. It pollinates itself without the [40] aid of insects, and is widely dispersed in cultivated fields. The third form, _V. alpestris_, grows in the Alps, but is of lesser importance for our present discussion. Anywhere throughout the central part of Europe _V. tricolor_ and _V. arvensis_ may be seen, each occupying its own locality. They may be considered as ranging among the most common native plants of the particular regions they inhabit. They vary in the color of the flowers, branching of the stems, in the foliage and other parts, but not to such an extent as to constitute distinct strains. They have been brought into cultivation by Jordan, Wittrock and others, but throughout Europe each of them constitutes a single type. These types must be very old and constant, fluctuating always within the same distinct and narrow limits. No slow, gradual changes can have taken place. In different countries their various habitats are as old as the historical records, and probably many centuries older. They are quite independent of one another, the distance being in numerous cases far too great for the exchange of pollen or of seeds. If slow and gradual changes were the rule, the types could not have remained so uniform throughout the whole range of these two species. They would necessarily have split up into thousands [41] and thousands of minor races, which would show their peculiar characteristics if tested by cultures in adjacent beds. This however, is not what happens. As a matter of fact _V. tricolor_ and _V. arvensis_ are widely distributed but wholly constant types. Besides these, there occur distinct types in numerous localities. Some of them evidently have had time and opportunity to spread more or less widely and now occupy larger regions or even whole countries. Others are narrowly limited, being restricted to a single locality. Wittrock collected seeds or plants from as many localities as possible in different parts of Sweden and neighboring states and sowed them in his garden near Stockholm. He secured seeds from his plants, and grew from them a second, and in many cases a third generation in order to estimate the amount of variability. As a rule the forms introduced into his garden proved constant, notwithstanding the new and abnormal conditions under which they were propagated. First of all we may mention three perennial forms called by him _Viola tricolor ammotropha_, _V. tricolor coniophila_ and _V. stenochila_. The typical _V. tricolor_ is an annual plant; sowing itself in summer and germinating soon afterwards. The young plants thrive throughout [42] the latter part of the summer and during the fall, reaching an advanced stage of development of the branched stems before winter. Early in the spring the flowers begin to open, but after the ripening of the seeds the whole plant dies. The three perennial species just mentioned develop in the same manner in the first year. During their flowering period, however, and afterwards, they produce new shoots from the lower parts of the stem. They prefer dry and sandy soils, often becoming covered with the sand that is blown on them by the winds. They are prepared for such seemingly adverse circumstances by the accumulation of food in the older stems and by the capacity of the new shoots to thrive on this food till they have become long enough to reach the light. _V. tricolor ammotropha_ is native near Ystad in Sweden, and the other two forms on Gotland. All three have narrowly limited habitats. The typical tricolored heartsease has remained annual in all its other subspecies. It may be divided into two types in the first place, _V. tricolor genuina_ and _V. tricolor versicolor_. Both of them have a wide distribution and seem to be the prototypes from which the rarer forms must have been derived. Among these latter Wittrock describes seven local types, which [43] proved to be constant in his pedigree-cultures. Some of them have produced other forms, related to them in the way of varieties. They all have nearly the same general habit and do not exhibit any marked differences in their growth, in the structure and branching of the stems, or in the character of their foliage. Differentiating points are to be found mainly in the colors and patterns of the flowers. The veins, which radiate from the centre of the corolla are branched in some and undivided in others; in one elementary species they are wholly lacking. The purple color may be absent, leaving the flowers of a pale or a deep yellow. Or the purple may be reddish or bluish. Of the petals all five may have the purple hue on their tips, or this attribute may be limited to the two upper ones. Contrasting with this wide variability is the stability of the yellow spot in the centre, which is always present and becomes inconspicuous only, when the whole petals are of the same hue. It is a general conception that colors and color-markings are liable to great variability and do not constitute reliable standards. But the cultures of Wittrock have proved the contrary, at least in the case of the violets. No pattern, however quaint, appears changeable, if one elementary species only is considered. Hundreds of plants from seeds [44] from one locality may be grown, and all will exhibit exactly the same markings. Most of these forms are of very local occurrence. The most beautiful of all, the _ornatissima_, is found only in Jemtland, the _aurobadia_ only in Sodermanland, the anopetala_ in other localities in the same country, the _roseola_ near Stockholm, and the yellow _lutescens_ in Finmarken. The researches of Wittrock included only a small number of elementary species, but every one who has observed the violets in the central parts of Europe must be convinced that many dozens of constant forms of the typical _Viola tricolor_ might easily be found and isolated. We now come to the field pansy, the _Viola arvensis_, a very common weed in the grain-fields of central Europe. I have already mentioned its small corolla, surpassed by the lobes of the calyx and its capacity of self-fertilization. It has still other curious differentiating characters; the pollen grains, which are square in _V. tricolor_, are five-sided in _V. arvensis_. Some transgressive fluctuating variability may occur in both cases through the admixture of pollen-grains. Even three-angled pollen grains are seen sometimes. Other marks are observed in the form of the anthers and the spur. There seem to be very many local subspecies [45] of the field-pansy. Jordan has described some from the vicinity of Lyons, and Wittrock others from the northern parts of Europe. They diverge from their common prototype in nearly all attributes, the flowers not showing the essential differentiating characters as in the _V. tricolor_. Some have their flower-stalks erect, and in others the flowers are held nearly at right angles to the stem. _V. pallescens_ is a small, almost unbranched species with small pale flowers. _V. segetalis_ is a stouter species with two dark blue spots on the tips of the upper petals. _V. agrestis_ is a tall and branched, hairy form. _V. nemausensis_ attains a height of only 10 cm., has rounded leaves and long flower-stalks. Even the seeds afford characters which may be made use of in isolating the various species. The above-mentioned elementary forms belong to the flora of southern France, and Wittrock has isolated and cultivated a number of others from the fields of Sweden. A species from Stockholm is called _Viola patens_; _V. arvensis curtisepala_ occurs in Gotland, and _V. arvensis striolata_ is a distinct form, which has appeared in his cultures without its true origin being ascertained. The alpine violets comprise a more widespread type with some local elementary species [46] derived exactly in the same way as the tricolored field pansies. Summarizing the general result of this description we see that the original species _Viola tricolor_ may be split up into larger and lesser groups of separate forms. These last prove to be constant in pedigree-cultures, and therefore are to be considered as really existent units. They are very numerous, comprising many dozens in each of the two larger subdivisions. All systematic grouping of these forms, and their combination into subspecies and species rests on the comparative study of their characters. The result of such studies must necessarily depend on principles which underlie them. According to the choice of these principles, the construction of the groups will be found to be different. Wittrock trusts in the first place to morphologic characters, and considers the development as passing from the more simple to the more complex types. On the other hand the geographic distribution may be considered as an indication of the direction of evolution, the wide-spread forms being regarded as the common parents of the minor local species. However, such considerations are only of secondary importance. It must be borne in mind that an ordinary systematic species may include [47] many dozens of elementary forms, each of which remains constant and unchanged in successive generations, even if cultivated in the same garden and under similar external conditions. Leaving the violets, we may take the vernal whitlow-grass or _Draba verna_ for a second illustration. This little annual cruciferous plant is common in the fields of many parts of the United States, though originally introduced from Europe. It has small basal rosettes which develop during summer and winter, and produce numerous leafless flowering stems early in the spring. It is a native of central Europe and western Asia, and may be considered as one of the most common plants, occurring anywhere in immense numbers on sandy soils. Jordan was the first to point out that it is not the same throughout its entire range. Although a hasty survey does not reveal differences, they show themselves on closer inspection. De Bary, Thuret, Rosen and many others confirmed this result, and repeated the pedigree-cultures of Jordan. Every type is constant and remains unchanged in successive generations. The anthers open in the flower-buds and pollinate the stigmas before the expansion of the flowers, thus assuring self-fertilization. Moreover, these inconspicuous little flowers are only sparingly visited by insects. Dozens of subspecies [48] may be cultivated in the same garden without any real danger of their intercrossing. They remain as pure as under perfect isolation. It is very interesting to observe the aspect of such types, when growing near each other. Hundreds of rosettes exhibit one type, and are undoubtedly similar. The alternative group is distinguishable at first sight, though the differentiating marks are often so slight as to be traceable with difficulty. Two elementary species occur in Holland, one with narrow leaves in the western provinces and one with broader foliage in the northern parts. I have cultivated them side by side, and was as much struck with the uniformity within each group, as with the contrast between the two sets. Nearly all organs show differences. The most marked are those of the leaves, which may be small or large, linear or elliptic or oblong and even rhomboidal in shape, more or less hairy with simple or with stellate branched hairs, and finally of a pure green or of a glaucous color. The petals are as a rule obcordate, but this type may be combined with others having more or less broad emarginations at the summit, and with differences in breadth which vary from almost linear types to others which touch along their margins. The pods are short and broad, or long and narrow, or varying in sundry other [49] ways. All in all there are constant differences which are so great that it has been possible to distinguish and to describe large numbers of types. Many of them have been tested as to their constancy from seed. Jordan made numerous cultures, some of which lasted ten or twelve years; Thuret has verified the assertion concerning their constancy by cultures extending over seven years in some instances; Villars and de Bary made numerous trials of shorter duration. All agree as to the main points. The local races are uniform and come true from seed; the variability of the species is not of a fluctuating, but of a polymorphous nature. A given elementary species keeps within its limits and cannot vary beyond them, but the whole group gives the impression of variability by its wide range of distinct, but nearly allied forms. The geographic distribution of these elementary species of the whitlow-grass is quite distinct from that of the violets. Here predominant species are limited to restricted localities. Most of them occupy one or more departments of France, and in Holland two of them are spread over several provinces. An important number are native in the centre of Europe, and from the vicinity of Lyons, Jordan succeeded in establishing about fifty elementary [50] species in his garden. In this region they are crowded together and not rarely two or even more quite distinct forms are observed to grow side by side on the same spot. Farther away from this center they are more widely dispersed, each holding its own in its habitat. In all, Jordan has distinguished about two hundred species of _Draba verna_ from Europe and western Asia. Subsequent authors have added new types to the already existing number from time to time. The constancy of these elementary species is directly proven by the experiments quoted above, and moreover it may be deduced from the uniformity of each type within its own domain. These are so large that most of the localities are practically isolated from one another, and must have been so for centuries. If the types were slowly changing such localities would often, though of course not always, exhibit slighter differences, and on the geographic limits of neighboring species intermediates would be found. Such however, are not on record. Hence the elementary species must be regarded as old and constant types. The question naturally arises how these groups of nearly allied forms may originally have been produced. Granting a common origin for all of them, the changes may have been [51] simultaneous or successive. According to the geographic distribution, the place of common origin must probably be sought in the southern part of central Europe, perhaps even in the vicinity of Lyons. Here we may assume that the old _Draba verna_ has produced a host or a swarm of new types. Thence they must have spread over Europe, but whether in doing so they have remained constant, or whether some or many of them have repeatedly undergone specific mutations, is of course unknown. The main fact is, that such a small species as _Draba verna_ is not at all a uniform type, but comprises over two hundred well distinguished and constant forms. It is readily granted that violets and whitlowgrasses are extreme instances of systematic variability. Such great numbers of elementary species are not often included in single species of the system. But the numbers are of secondary importance, and the fact that systematic species consist, as a rule, of more than one independent and constant subspecies, retains its almost universal validity. In some cases the systematic species are manifest groups, sharply differentiated from one another. In other instances the groups of elementary forms as they are shown by direct observation, have been adjudged by many authors [52] to be too large to constitute species. Hence the polymorphous genera, concerning the systematic subdivisions of which hardly two authors agree. Brambles and roses are widely known instances, but oaks, elms, apples, and pears, _Mentha_, _Prunu_s, _Vitis_, _Lactuca_, _Cucumis_, _Cucurbita_ and numerous others are in the same condition. In some instances the existence of elementary species is so obvious, that they have been described by taxonomists as systematic varieties or even as good species. The primroses afford a widely known example. Linnaeus called them _Primula veris_, and recognized three types as pertaining to this species, but Jacquin and others have elevated these subspecies to the full rank of species. They now bear the names of _Primula elatior_ with larger, _P. officinalis_ with smaller flowers, and _P. acaulis_. In the last named the common flower-stalk is lacking and the flowers of the umbel seem to be borne in the arils of the basal leaves. In other genera such nearly allied species are more or less universally recognized. _Galium Mollugo_ has been divided into _G. elatum_ with a long and weak stem, and _G. erectum_ with shorter and erect stems; _Cochlearia danica_, _anglica_ and _officinalis_ are so nearly allied as to be hardly distinguishable. _Sagina apetala_ and _patula_, [53] _Spergula media_ and _salina_ and many other pairs of allied species have differentiating characters of the same value as those of the elementary species of _Draba verna_. _Filago_, _Plantago_, _Carex_, _Ficaria_ and a long series of other genera afford proofs of the same close relation between smaller and larger groups of species. The European frost-weeds or _Helianthemum_ include a group of species which are so closely allied, that ordinary botanical descriptions are not adequate to give any idea of their differentiating features. It is almost impossible to determine them by means of the common analytical keys. They have to be gathered from their various native localities and cultivated side by side in the garden to bring out their differences. Among the species of France, according to Jordan, _Helianthemum polifolium_, _H. apenninum_, _H. pilosum_ and _H. pulverulentum_ are of this character. A species of cinquefoil, _Potentilla Tormentilla_, which is distinguished by its quaternate flowers, occurs in Holland in two distinct types, which have proved constant in my cultural experiments. One of them has, broad petals, meeting together at the edges, and constituting rounded saucer without breaks. The other has narrow petals, which are strikingly separated from one another and show the sepals between them. [54] In the same manner bluebells vary in the size and shape of the corolla, which may be wide or narrow, bell-shaped or conical, with the tips turned downwards, sidewards or backwards. As a rule all of the more striking elementary types have been described by local botanists under distinct specific names, while they are thrown together into the larger systematic species by other authors, who study the distribution of plants over larger portions of the world. Everything depends on the point of view taken. Large floras require large species. But the study of local floras yields the best results if the many forms of the region are distinguished and described as completely as possible. And the easiest way is to give to each of them a specific name. If two or more elementary species are united in the same district, they are often treated in this way, but if each region had its own type of some given species, commonly the part is taken for the whole, and the sundry forms are described under the same name, without further distinctions. Of course these questions are all of a practical and conventional nature, but involve the different methods in which different authors deal with the same general fact. The fact is that systematic species are compound groups, exactly like the genera and that their real units [55] can only be recognized by comparative experimental studies. Though the evidence already given might be esteemed to be sufficient for our purpose, I should like to introduce a few more examples; two of them pertain to American plants. The Ipecac spurge or _Euphorbia Ipecacuanha_ occurs from Connecticut to Florida, mainly near the coast, preferring dry and sandy soil. It is often found by the roadsides. According to Britton and Brown's "Illustrated Flora" it is glabrous or pubescent, with several or many stems, ascending or nearly erect; with green or red leaves, which are wonderfully variable in outline, from linear to orbicular, mostly opposite, the upper sometimes whorled, the lower often alternate. The glands of the involucres are elliptic or oblong, and even the seeds vary in shape. Such a wide range of variability evidently points to the existence of some minor types. Dr. John Harshberger has made a study of those which occur in the vicinity of Whitings in New Jersey. His types agree with the description given above. Others were gathered by him at Brown's Mills in the pinelands, New Jersey, where they grew in almost pure sand in the bright sunlight. He observed still other differentiating characters. The amount of seed [56] produced and the time of flowering were variable to a remarkable degree. Dr. Harshberger had the kindness to send me some dried specimens of the most interesting of these types. They show that the peculiarities are individual, and that each specimen has its own characters. It is very probable that a comparative experimental study will prove the existence of a large number of elementary species, differing in many points; they will probably also show differences in the amount of the active chemical substances, especially of emetine, which is usually recorded as present in about 1%, but which will undoubtedly be found in larger quantities in some, and in smaller quantities in other elementary species. In this way the close and careful distinction of the really existing units might perhaps prove of practical importance. MacFarlane has studied the beach-plum or _Prunus maritima_, which is abundant along the coast regions of the Eastern States from Virginia to New Brunswick. It often covers areas from two to two hundred acres in extent, sometimes to the exclusion of other plants. It is most prolific on soft drifting sand near the sea or along the shore, where it may at times be washed with ocean-spray. The fruit usually become ripe about the middle of August, and show extreme [57] variations in size, shape, color, taste, consistency and maturation period, indicating the existence of separate races or elementary species, with widely differing qualities. The earlier varieties begin to ripen from August 10 to 20, and a continuous supply can be had till September 10, while a few good varieties continue to ripen till September 20. But even late in October some other types are still found maturing their fruits. Exact studies were made of fruit and stone variations, and their characteristics as to color, weight, size, shape and consistency were fully described. Similar variations have been observed, as is well known, in the cultivated plums. Fine blue-black fruits were seen on some shrubs and purplish or yellow fruits on others. Some exhibit a firmer texture and others a more watery pulp. Even the stones show differences which are suggestive of distinct races. Recently Mr. Luther Burbank of Santa Rosa, California, has made use of the beach-plum to produce useful new varieties. He observed that it is a very hardy species, and never fails to bear, growing under the most trying conditions of dry and sandy, or of rocky and even of heavy soil. The fruits of the wild shrubs are utterly worthless for anything but preserving. [58] But by means of crossing with other species and especially with the Japanese plums, the hardy qualities of the beach-plum have been united with the size, flavor and other valuable qualities of the fruit, and a group of new plums have been produced with bright colors, ovoid and globular forms which are never flattened and have no suture. The experiments were not finished, when I visited Mr. Burbank in July, 1904, and still more startling improvements were said to have been secured. I may perhaps be allowed to avail myself of this opportunity to point out a practical side of the study of elementary species. This always appears whenever wild plants are subjected to cultivation, either in order to reproduce them as pure strains, or to cross them with other already cultivated species. The latter practice is as a rule made use of whenever a wild species is found to be in possession of some quality which is considered as desirable for the cultivated forms. In the case of the beach-plum it is the hardiness and the great abundance of fruits of the wild species which might profitably be combined with the recognized qualities of the ordinary plums. Now it is manifest, that in order to make crosses, distinct individual plants are to be chosen, and that the variability of the wild species may be of very great importance. [59] Among the range of elementary species those should be used which not only possess the desired advantages in the highest degree, but which promise the best results in other respects or their earliest attainment. The fuller our knowledge of the elementary species constituting the systematic groups, the easier and the more reliable will be the choice for the breeder. Many Californian wild flowers with bright colors seem to consist of large numbers of constant elementary forms, as for instance, the lilies, godetias, eschscholtias and others. They have been brought into cultivation many times, but the minutest distinction of their elementary forms is required to attain the highest success. In concluding, I will point out a very interesting difficulty, which in some cases impedes the clear understanding of elementary species. It is the lack of self-fertilization. It occurs in widely distant families, but has a special interest for us in two genera, which are generally known as very polymorphous groups. One of them is the hawkweed or _Hieracium_, and the other is the dandelion or _Taraxacum officinale_. Hawkweeds are known as a genus in which the delimitation of the species is almost impossible, Thousands of forms may be cultivated side by side in botanical gardens, exhibiting [60] slight but undoubted differentiating features, and reproduce themselves truly by seed. Descriptions were formerly difficult and so complicated that the ablest writers on this genus, Fries and Nageli are said not to have been able to recognize the separate species by the descriptions given by each other. Are these types to be considered as elementary species, or only as individual differences? The decision of course, would depend upon their behavior in cultures. Such tests have been made by various experimenters. In the dandelion the bracts of the involucre give the best characters. The inner ones may be linear or linear-lanceolate, with or without appendages below the tip; the outer ones may be similar and only shorter, or noticeably larger, erect, spreading or even reflexed, and the color of the involucre may be a pure green or glaucous; the leaves may be nearly entire or pinnatifid, or sinuate-dentate, or very deeply runcinate-pinnatifid, or even pinnately divided, the whole plant being more or less glabrous. Raunkiaer, who has studied experimentally a dozen types from Denmark, found them constant, but observed that some of them have no pollen at all, while in others the pollen, though present, is impotent. It does not germinate on the stigma, cannot produce the ordinary tube, [61] and hence has no fertilizing power. But the young ovaries do not need such fertilization. They are sufficient unto themselves. One may cut off all the flowers of a head before the opening of the anthers, and leave the ovaries untouched, and the head will ripen its seeds quite as well. The same thing occurs in the hawkweeds. Here, therefore, we have no fertilization and the extensive widening of the variability, which generally accompanies this process is, of course, wanting. Only partial or vegetative variability is present. Unfertilized eggs when developing into embryos are equivalent to buds, separated from the parent-plant and planted for themselves. They repeat both the specific and the individual characters of the parent. In the case of the hawkweed and the dandelion there is at present no means of distinguishing between these two contrasting causes of variability. But like the garden varieties which are always propagated in the vegetative way, their constancy and uniformity are only apparent and afford no real indication of hereditary qualities. In addition to these and other exceptional cases, seed-cultures are henceforth to be considered as the sole means of recognizing the really existing systematic units of nature. All other groups, including systematic species and [62] genera, are equally artificial or conventional. In other words we may state "that current misconceptions as to the extreme range of fluctuating variability of many native species have generally arisen from a failure to recognize the composite nature of the forms in question," as has been demonstrated by MacDougal in the case of the common evening-primrose, _Oenothera biennis_. "It is evident that to study the behavior of the characters of plants we must have them in their simplest combinations; to investigate the origin and movements of species we must deal with them singly and uncomplicated." [63] LECTURE III ELEMENTARY SPECIES OF CULTIVATED PLANTS Recalling the results of the last lecture, we see that the species of the systematists are not in reality units, though in the ordinary course of floristic studies they may, as a rule, seem to be so. In some cases representatives of the same species from different countries or regions, when compared with one another do not exactly agree. Many species of ferns afford instances of this rule, and Lindley and other great systematists have frequently been puzzled by the wide range of differences between the individuals of a single species. In other cases the differing forms are observed to grow near each other, sometimes in neighboring provinces, sometimes in the same locality, growing and flowering in mixtures of two or three or even more elementary types. The violets exhibit widespread ancient types, from which the local species may be taken to have arisen. The common ancestors of the Whitlow-grasses are probably not to be found [64] among existing forms, but numerous types are crowded together in the southern part of central Europe and more thinly scattered elsewhere, even as far as western Asia. There can be little doubt that their common origin is to be sought in the center of their geographic distribution. Numerous other cases exhibit smaller numbers of elementary units within a systematic species; in fact purely uniform species seem to be relatively rare. But with small numbers there are of course no indications to be expected concerning their common origin or the starting point of their distribution. It is manifest that these experiences with wild species must find a parallel among cultivated plants. Of course cultivated plants were originally wild and must have come under the general law. Hence we may conclude that when first observed and taken up by man, they must already have consisted of sundry elementary subspecies. And we may confidently assert that some must have been rich and others poor in such types. Granting this state of things as the only probable one, we can easily imagine what must have been the consequences. If a wild species had been taken into cultivation only once, the cultivated form would have been a single elementary [65] type. But it is not very likely that such partiality would occur often. The conception that different tribes at different times and in distant countries would have used the wild plants of their native regions seems far more natural than that all should have obtained plants for cultivation from the same source or locality. If this theory may be relied upon, the origin of many of the more widely cultivated agricultural plants must have been multiple, and the number of the original elementary species of the cultivated types must have been so much the larger, the more widely distributed and variable the plants under consideration were before the first period of cultivation. Further it would seem only natural to explain the wide variability of many of our larger agricultural and horticultural stocks by such an incipient multiformity of the species themselves. Through commercial intercourse the various types might have become mixed so as to make it quite impossible to point out the native localities for each of them. Unfortunately historical evidence on this point is almost wholly lacking. The differences in question could not have been appreciated at that remote period, and interest the common observer but little even today. The history of most of the cultivated plants is very obscure, [66] and even the most skillful historians, by sifting the evidence afforded by the older writers, and that obtained by comparative linguistic investigations have been able to do little more than frame the most general outline of the cultural history of the most common and most widely used plants. Some authors assume that cultivation itself might have been the principal cause of variability, but it is not proved, nor even probable, that cultivated plants are intrinsically more variable than their wild prototypes. Appearances in this case are very deceptive. Of course widely distributed plants are as a rule richer in subspecies than forms with limited distribution, and the former must have had a better chance to be taken into cultivation than the latter. In many cases, especially with the more recent cultivated species, man has deliberately chosen variable forms, because of their greater promise. Thirdly, wide variability is the most efficient means of acclimatization, and only species with many elementary units would have offered the adequate material for introduction into new countries. From this discussion it would seem that it is more reasonable to assert that variability is one of the causes of the success of cultivation, than to assume that cultivation is a cause of variability [67] at large. And this assumption would be equally sufficient to explain the existing conditions among cultivated plants. Of course I do not pretend to say that cultivated plants should be expected to be less variable than in the wild state, or that swarms of elementary species might not be produced during cultivation quite as well as before. However the chance of such an event, as is easily seen, cannot be very great, and we shall have to be content with a few examples of which the coconut is a notable one. Leaving this general discussion of the subject, we may take up the example of the beets. The sugar-beet is only one type from among a horde of others, and though the origin of all the single types is not historically known, the plant is frequently found in the wild state even at the present time, and the native types may be compared with the corresponding cultivated varieties. The cultivation of beets for sugar is not of very ancient date. The Romans knew the beets and used them as vegetables, both the roots and the leaves. They distinguished a variety with white and one with red flesh, but whether they cultivated them, or only collected them from where they grew spontaneously, appears to be unknown. [68] Beets are even now found in large quantities along the shores of Italy. They prefer the vicinity of the sea, as do so many other members of the beet family, and are not limited to Italy, but are found growing elsewhere on the littoral of the Mediterranean, in the Canary Islands and through Persia and Babylonia to India. In most of their native localities they occur in great abundance. The color of the foliage and the size of the roots are extremely variable. Some have red leafstalks and veins, others a uniform red or green foliage, some have red or white or yellow roots, or exhibit alternating rings of a red and of a white tinge on cut surfaces. It seems only natural to consider the white and the red, and even the variegated types as distinct varieties, which in nature do not transgress their limits nor change into one another. In a subsequent lecture I will show that this at least is the rule with the corresponding color-varieties in other genera. The fleshiness or pulpiness of the roots is still more variable. Some are as thick as the arm and edible, others are not thicker than a finger and of a woody composition, and the structure of this woody variety is very interesting. The sugar-beet consists, as is generally known, of concentric layers of sugar-tissue and of vascular [69] strands; the larger the first and the smaller the latter, the greater is, as a rule, the average amount of sugar of the race. Through the kindness of the late Mr. Rimpau, a well known German breeder of sugar-beet varieties, I obtained specimens from seed of a native wild locality near Bukharest. The plants produced quite woody roots, showing almost no sugar tissue at all. Woody layers of strongly developed fibrovascular strands were seen to be separated one from another only by very thin layers of parenchymatous cells. Even the number of layers is variable; it was observed to be five in my plants; but in larger roots double this number and even more may easily be met with. Some authors have distinguished specific types among these wild forms. While the cultivated beets are collected under the head of _Beta vulgaris_, separate types with more or less woody roots have been described as _Beta maritima_ and _Beta patula_. These show differences in the habit of the stems and the foliage. Some have a strong tendency to become annual, others to become biennial. The first of course do not store a large quantity of food in their roots, and remain thin, even at the time of flowering. The biennial types occur in all sizes of roots. In the annuals the stems may vary from [70] erect to ascending, and the name _patula_ indicates stems which are densely branching from the base with widely spreading branches throughout. Mr. Em. von Proskowetz of Kwassitz, Austria, kindly sent me seeds of this _Beta patula_, the variability of which was so great in my cultures as to range from nearly typical sugar-beets to the thin woody type of Bukharest. Broad and narrow leaves are considered to be differentiating marks between _Beta vulgaris_ and _Beta patula_, but even here a wide range of forms seem to occur. Rimpau, Proskowetz, Schindler and others have made cultures of beets from wild localities in order to discover a hypothetical common ancestor of all the present cultivated types. These researches point to the _B. patula_ as the probable ancestor, but of course they were not made to decide the question as to whether the origination of the several now existing types had taken place before or during culture. From a general point of view the variability of the wild species is parallel to that of the cultivated forms to such a degree as to suggest the multiple origin of the former. But a close investigation of this highly important problem has still to be made. The varieties of the cultivated beets are commonly [71] included in four subspecies. The two smallest are the salad-beets and the ornamental forms, the first being used as food, and ordinarily cultivated in red varieties, the second being used as ornamental plants during the fall, when they fill the beds left empty by summer flowers, with a bright foliage that is exceedingly rich in form and color. Of the remaining subspecies, one comprises the numerous sorts cultivated as forage-crops and the other the true sugar-beets. Both of them vary widely as to the shape and the size of the roots, the quality of the tissue, the foliage and other characteristics. Some of these forms, no doubt, have originated during culture. Most of them have been improved by selection, and no beet found in the wild state ever rivals any cultivated variety. But the improvement chiefly affects the size, the amount of sugar and nutrient substances and some other qualities which recur in most of the varieties. The varietal attributes themselves however, are more or less of a specific nature, and have no relation to the real industrial value of the race. The short-rooted and the horn-shaped varieties might best be cited as examples. The assertion that the sundry varieties of forage-beets are not the result of artificial selection, [72] is supported in a large measure by the historic fact that the most of them are far older than the method of conscious selection of plants itself. This method is due to Louis Vilmorin and dates from the middle of the last century. But in the sixteenth century most of our present varieties of beets were already in cultivation. Caspar Bauhin gives a list of the beets of his time and it is not difficult to recognize in it a large series of subspecies and varieties and even of special forms, which are still cultivated. A more complete list was published towards the close of the same century by Olivier de Serres in his world-renowned "Theatre d'Agriculture" (Paris, 1600). The red forage-beets which are now cultivated on so large a scale, had been introduced from Italy into France only a short time before. From this historic evidence, the period during which the beets were cultivated from the time of the Romans or perhaps much later, up to the time of Bauhin and De Serres, would seem far too short for the production by the unguided selection of man of all the now existing types. On the other hand, the parallelism between the characters of some wild and some cultivated varieties goes to make it very probable that other varieties have been found in the same way, some in this country and others in that, [73] and have been taken into cultivation separately. Afterwards of course all must have been improved in the direction required by the needs of man. Quite the same conclusion is afforded by apples. The facts are to some extent of another character, and the rule of the derivation of the present cultivated varieties from original wild forms can be illustrated in this case in a more direct way. Of course we must limit ourselves to the varieties of pure ancestry and leave aside all those which are of hybrid or presumably hybrid origin. Before considering their present state of culture, something must be, said about the earlier history and the wild state of the apples. The apple-tree is a common shrub in woods throughout all parts of Europe, with the only exception of the extreme north. Its distribution extends to Anatolia, the Caucasus and Ghilan in Persia. It is found in nearly all forests of any extent and often in relatively large numbers of individuals. It exhibits varietal characters, which have led to the recognition of several spontaneous forms, especially in France and in Germany. The differentiating qualities relate to the shape and indumentum of the leaves. Nothing is known botanically as to differences between [74] the fruits of these varieties, but as a matter of fact the wild apples of different countries are not at all the same. Alphonse De Candolle, who made a profound study of the probable origin of most of our cultivated plants, comes to the conclusion that the apple tree must have had this wide distribution in prehistoric times, and that its cultivation began in ancient times everywhere. This very important conclusion by so high an authority throws considerable light on the relation between cultivated and wild varieties at large. If the historic facts go to prove a multiple origin for the cultivation of some of the more important useful plants, the probability that different varieties or elementary species have been the starting points for different lines of culture, evidently becomes stronger. Unfortunately, this historic evidence is scanty. The most interesting facts are those concerning the use of apples by the Romans and by their contemporaries of the Swiss and middle European lake-dwellings. Oswald Heer has collected large numbers of the relics of this prehistoric period. Apples were found in large quantities, ordinarily cut into halves and with the signs of having been dried. Heer distinguished two varieties, one with large and one with small fruits. The first about 3 and [75] the other about 1.5-2 cm. in diameter. Both are therefore very small compared with our present ordinary varieties, but of the same general size as the wild forms of the present day. Like these, they must have been of a more woody and less fleshy tissue. They would scarcely have been tasteful to us, but in ancient times no better varieties were known and therefore no comparison was possible. There is no evidence concerning the question, as to whether during the periods mentioned apples were cultivated or only collected in the wild state. The very large numbers which are found, have induced some writers to believe in their culture, but then there is no reason why they should not have been collected in quantity from wild shrubs. The main fact is that the apple was not a uniform species in prehistoric times but showed even then at least some amount of variability. At the present day the wild apples are very rich in elementary species. Those of Versailles are not the same as those of Belgium, and still others are growing in England and in Germany. The botanical differences derived from the blossoms and the leaves are slight, but the flavor, size and shape of the fruits diverge widely. Two opinions have been advanced to explain this high degree of variability, but [76] neither of them conveys a real explanation; their aim is chiefly to support different views as to the causes of variability, and the origin of elementary species at large. One opinion, advocated by De Candolle, Darwin and others, claims that the varieties owe their origin to the direct influence of cultivation, and that the corresponding forms found in the wild state, are not at all original, but have escaped from cultivation and apparently become wild. Of course this possibility cannot be denied, at least in any single instance, but it seems too sweeping an assertion to make for the whole range of observed forms. The alternative theory is that of van Mons, the Belgian originator of commercial varieties of apples, who has published his experiments in a large work called "Arbres fruitiers ou Pomonomie belge." Most of the more remarkable apples of the first half of the last century were produced by van Mons, but his greatest merit is not the direct production of a number of good varieties, but the foundation of the method, by which new varieties may be obtained and improved. According to van Mons, the production of a new variety consists chiefly of two parts. The first is the discovery of a subspecies with new desirable qualities. The second is the transformation [77] of the original small and woody apple into a large, fleshy and palatable variety. Subspecies, or what we now call elementary species were not produced by man; nature alone creates new forms, as van Mons has it. He examined with great care the wild apples of his country, and especially those of the Ardennes, and found among them a number of species with different flavors. For the flavor is the one great point, which must be found ready in nature and which may be improved, but can never be created by artificial selection. The numerous differences in flavor are quite original; all of them may be found in the wild state and most of them even in so limited a region as the Ardennes Mountains. Of course van Mons preferred not to start from the wild types themselves, when the same flavor could be met with in some cultivated variety. His general method was, to search for a new flavor and to try to bring the bearer of it up to the desired standard of size and edibility. The latter improvement, though it always makes the impression of an achievement, is only the last stone to be added to the building up of the commercial value of the variety. Without it, the best flavored apple remains a crab; with it, it becomes a conquest. According to the method of van Mons it may be reached within [78] two or three generations, and a man's life is wholly sufficient to produce in this way many new types of the very best sorts, as van Mons himself has done. It is done in the usual way, sowing on a large scale and selecting the best, which are in their turn brought to an early maturation of their fruit by grafting, because thereby the life from seed to seed may be reduced to a few years. Form, taste, color, flavor and other valuable marks of new varieties are the products of nature, says van Mons, only texture, fleshiness and size are added by man. And this is done in each new variety by the same method and according to the same laws. The richness of the cultivated apples of the present day was already present in the large range of original wild elementary species, though unobserved and requiring improvement. An interesting proof of this principle is afforded by the experience of Mr. Peter M. Gideon, as related by Bailey. Gideon sowed large quantities of apple-seeds, and one seed produced a new and valuable variety called by him the "Wealthy" apple. He first planted a bushel of apple-seeds, and then every year, for nine years, planted enough seeds to produce a thousand trees. At the end of ten years all seedlings had perished except one hardy seedling [79] crab. This experiment was made in Minnesota, and failed wholly. Then he bought a small lot of seeds of apples and crab-apples in Maine and from these the "Wealthy" came. There were only about fifty seeds in the lot of crab-apple seed which produced the "Wealthy," but before this variety was obtained, more than a bushel of seed had been sown. Chance afforded a species with an unknown taste; but the growing of many thousands of seedlings of known varieties was not the best means to get something really new. Pears are more difficult to improve than apples. They often require six or more generations to be brought from the wild woody state to the ordinary edible condition. But the varieties each seem to have a separate origin, as with apples, and the wide range of form and of taste must have been present in the wild state, long before cultivation. Only recently has the improvement of cherries, plums, currants and gooseberries been undertaken with success by Mr. Burbank, and the difference between the wild and cultivated forms has hitherto been very small. All indications point to the existence, before the era of cultivation, of larger or smaller numbers of elementary species. The same holds good with many of the larger forage crops and other plants of great industrial [80] value. Clover exhibits many varieties, which have been cultivated indiscriminately, and often in motley mixtures. The flower heads may be red or white, large or small, cylindric or rounded, the leaves are broader or narrower, with or without white spots of a curious pattern. They may be more or less hairy and so forth. Even the seeds exhibit differences in size, shape or color, and of late Martinet has shown, that by the simple means of picking out seeds of the same pattern, pure strains of clover may be obtained, which are of varying cultural value. In this way the best subspecies or varieties may be sought out for separate cultivation. Even the white spots on the leaflets have proved to be constant characters corresponding with noticeable differences in yield. Flax is another instance. It was already cultivated, or at least made use of during the period of the lake-dwellers, but at that time it was a species referred to as _Linum angustifolium_, and not the _Linum usitatissimum_, which is our present day flax. There are now many subspecies, elementary species, and varieties under cultivation. The oldest of them is known as the "springing flax," in opposition to the ordinary "threshing flax." It has capsules which open of themselves, in order to disseminate the seeds, while the ordinary heads of the [81] flax remain closed until the seeds are liberated by threshing. It seems probable that the first form or _Linum crepitans_ might thrive in the wild state as well as any other plant, while in the common species those qualities are lacking which are required for a normal dissemination of the seeds. White or blue flowers, high or dwarf stems, more or less branching at the base and sundry other qualities distinguish the varieties, aside from the special industrial difference of the fibres. Even the life-history varies from annual and biennial, to perennial. It would take us too long to consider other instances. It is well known that corn, though considered as a single botanical species, is represented by different subspecies and varieties in nearly every region in which it is grown. Of course its history is unknown and it is impossible to decide whether all the tall and dwarf forms, or starchy and sweet varieties, dented or rounded kernels, and hundreds of others are older than culture or have come into existence during historic times, or as some assume, through the agency of man. But our main point now is not the origin, but only the existence of constant and sharply differentiated forms within botanical species. Nearly every cultivated plant affords instances of such diversity. Some include a few types only, while [82] others show, a large number of forms clearly separated to a greater or lesser degree. In some few instances it is obvious that this variability is of later date than culture. The most conspicuous case is that of the coconut. This valuable palm is found on nearly all tropical coasts, in America, as well as in Asia, but in Africa and Australia there are many hundreds of miles of shore line, where it is not found. Its importance is not at all the same everywhere. On the shores and islands of the Indian Ocean and the Malay Archipelago, man is chiefly dependent upon it, but in America it is only of subordinate usefulness. In connection with these facts, it abounds in subspecies and varieties in the East Indian regions, but on the continent of America little attention has as yet been given to its diverging qualities. In the Malayan region it affords nearly all that is required by the inhabitants. The value of its fruit as food, and the delicious beverage which it yields, are well known. The fibrous rind is not less useful; it is manufactured into a kind of cordage, mats and floor-cloths. An excellent oil is obtained from the kernel by compression. The hard covering of the stem is converted into drums and used in the construction of huts; the lower part is so hard as to take on a beautiful polish [83] when it resembles agate. Finally the unexpanded terminal bud is a delicate article of food. Many other uses could be mentioned, but these may suffice to indicate how closely the life of the inhabitants is bound up with the culture of this palm, and how sharply, in consequence, its qualities must have been watched by early man. Any divergence from the ordinary type must have been noted; those which were injurious must have been rejected, but the useful ones must have been appreciated and propagated. In a word any degree of variability afforded by nature must have been noticed and cultivated. More than fifty different sorts of the coconut are described from the Indian shores and islands, with distinct local and botanical names. Miquel, who was one of the best systematists of tropical plants, of the last century, described a large number of them, and since, more have been added. Nearly all useful qualities vary in a higher or lesser degree in the different varieties. The fibrous strands of the rind of the nut are developed in some forms to such a length and strength as to yield the industrial product known as the coir-fibre. Only three of them are mentioned by Miquel that have this quality, the _Cocos nucifera rutila_, _cupuliformis_ and _stupposa_. Among them the _rutila_ [84] yields the best and most supple fibres, while those of the _stupposa_ are stiff and almost unbending. The varieties also differ greatly in size, color, shape and quality, and the trees have also peculiar characteristics. One variety exhibits leaves which are nearly entire, the divisions being only imperfectly separated, as often occurs in the very first leaves of the seedlings of other varieties. The flavor of the flesh, oil and milk likewise yield many good varietal marks. In short, the coconut-palm comes under the general rule, that botanical species are built up of a number of sharply distinguishable types, which prove their constancy and relative independence by their wide distribution in culture. In systematic works all these forms are called varieties, and a closer investigation of their real systematic value has not yet been made. But the question as to the origin of the varieties and of the coconut itself has engrossed the attention of many botanists, among whom are De Candolle in the middle of the last century, and Cook at its close. Both questions are closely connected. De Candolle claimed an Asiatic origin for the whole species, while Cook's studies go to prove that its original habitat is to be sought in the northern countries of South America. Numerous [85] varieties are growing in Asia and have as yet not been observed to occur in America, where the coconut is only of subordinate importance, being one of many useful plants, and not the only one relied upon by the natives for their subsistence. If therefore, De Candolle's opinion is the right one, the question as to whether the varieties are older or younger than the cultivated forms of the species, must always remain obscure. But if the proofs of an American origin should be forthcoming, the possibility, and even the probability that the varieties are of later date than the beginning of their culture, and have originated while in this condition must at once be granted. An important point in the controversy is the manner in which the coconuts were disseminated from shore to shore, from island to island. De Candolle, Darwin and most of the European writers claim that the dispersal was by natural agencies, such as ocean-currents. They point out that the fibrous rind or husk would keep the fruits afloat, and uninjured, for many days or even many weeks, while being carried from one country to another in a manner that would explain their geographic distribution. But the probability of the nuts being thrown upon the strand, and far enough from the shore to find suitable conditions for their germination, is a very small one. To insure [86] healthy and vigorous seedlings the nuts must be fully ripe, after which planting cannot be safely delayed for more than a few weeks. If kept too moist the nuts rot. If once on the shore, and allowed to lie in the sun, they become overheated and are thereby destroyed; if thrown in the shade of other shrubs and trees, the seedlings do not find the required conditions for a vigorous growth. Some authors have taken the fibrous rind to be especially adapted to transport by sea, but if this were so, this would argue that water is the normal or at least the very frequent medium of dissemination, which of course it is not. We may, claim with quite as much right that the thick husk is necessary to enable the heavy fruit to drop from tall trees with safety. But even for this purpose the protection is not sufficient, as the nuts often suffer from falling to such a degree as to be badly injured as to their germinating qualities. It is well known that nuts, which are destined for propagation, are as a rule not allowed to fall off, but are taken from the trees with great care. Summing up his arguments, Cook concludes that there is little in the way of known facts to support the poetic theory of the coconut palm dropping its fruits into the sea to float away to barren islands and prepare them for [87] human habitation. Shipwrecks might furnish a successful method of launching viable coconuts, and such have no doubt sometimes contributed to their distribution. But this assumption implies a dissemination of the nuts by man, and if this principal fact is granted, it is far more natural to believe in a conscious intelligent dissemination. The coconut is a cultivated tree. It may be met with in some spots distant from human dwellings, but whenever such cases have been subjected to a closer scrutiny, it appears that evidently, or at least probably, huts had formerly existed in their neighborhood, but having been destroyed by some accident, had left the palm trees uninjured. Even in South America, where it may be found in forests at great distances from the sea-shore, it is not at all certain that true native localities occur, and it seems to be quite lost in its natural condition. Granting the cultivated state of the palms as the only really important one, and considering the impossibility or at least great improbability of its dissemination by natural means, the distribution by man himself, according to his wants, assumes the rank of an hypothesis fully adequate to the explanation of all the facts concerning the life-history of the tree. We now have to inquire into the main question, [88] whether it is probable that the coconut is of American or of Asiatic origin, leaving aside the historic evidence which goes to prove that nothing is known about the period in which its dissemination from one hemisphere to another took place, we will now consider only the botanic and geographic evidence, brought forward by Cook. He states that the whole family of coconut-palms, consisting of about 20 genera and 200 species, are all strictly American with the exception of the rather aberrant African oilpalm, which has, however, an American relative referred to the same genus. The coconut is the sole representative of this group which is connected with Asia and the Malayan region, but there is no manifest reason why other members of the same group could not have established themselves there, and maintained an existence under conditions, which are not at all unfavorable to them. The only obvious reason is the assumption already made, that the distribution was brought about by man, and thus only affected the species, chosen by him for cultivation. That the coconut cannot have been imported from Asia into America seems to be the most obvious conclusion from the arguments given. It should be briefly noted, that it was known and widely distributed in tropical America at the time of the discovery of that continent [89] by Columbus, according to accounts of Oviedo and other contemporary Spanish writers. Concluding we may state that according to the whole evidence as it has been discussed by De Candolle and especially by Cook, the coconut-palm is of American origin and has been distributed as a cultivated tree by man through the whole of its wide range. This must have happened in a prehistoric era, thus affording time enough for the subsequent development of the fifty and more known varieties. But the possibility that at least some of them have originated before culture and have been deliberately chosen by man for distribution, of course remains unsettled. Coconuts are not very well adapted for natural dispersal on land, and this would rather induce us to suppose an origin within the period of cultivation for the whole group. There are a large number of cultivated varieties of different species which by some peculiarity do not seem adapted for the conditions of life in the wild state. These last have often been used to prove the origin of varietal forms during culture. One of the oldest instances is the variety or rather subspecies of the opium-poppy, which lacks the ability to burst open its capsules. The seeds, which are thrown out by the wind, in the common forms, through the apertures underneath [90] the stigma, remain enclosed. This is manifestly a very useful adaptation for a cultivated plant, as by this means no seeds are lost. It would be quite a disadvantage for a wild species, and is therefore claimed to have been connected from the beginning with the cultivated form. The large kernels of corn and grain, of beans and peas, and even of the lupines were considered by Darwin and others to be unable to cope with natural conditions of life. Many valuable fruits are quite sterile, or produce extremely few seeds. This is notoriously the case with some of the best pears and grapes, with the pine-apples, bananas, bread-fruits, pomegranate and some members of the orange tribe. It is open to discussion as to what may be the immediate cause of this sterility, but it is quite evident, that all such sterile varieties must have originated in a cultivated condition. Otherwise they would surely have been lost. In horticulture and agriculture the fact that new varieties arise from time to time is beyond all doubt, and it is not this question with which we are now concerned. Our arguments were only intended to prove that cultivated species, as a rule, are derived from wild species, which obey the laws discussed in a previous lecture. The botanic units are compound entities, and [91] the real systematic units in elementary species play the same part as in ordinary wild species. The inference that the origin of the cultivated plants is multiple, in most cases, and that more than one, often many separate elementary forms of the same species must originally have been taken into cultivation, throws much light upon many highly important problems of cultivation and selection. This aspect of the question will therefore be the subject of the next lecture. [92] LECTURE IV SELECTION OF ELEMENTARY SPECIES The improvement of cultivated plants must obviously begin with already existing forms. This is true of old cultivated sorts as well as for recent introductions. In either case the starting-point is as important as the improvement, or rather the results depend in a far higher degree on the adequate choice of the initial material than on the methodical and careful treatment of the chosen varieties. This however, has not always been appreciated as it deserves, nor is its importance at present universally recognized. The method of selecting plants for the improvement of the race was discovered by Louis Vilmorin about the middle of the last century. Before his time selection was applied to domestic animals, but Vilmorin was the first to apply this principle to plants. As is well known, he used this method to increase the amount of sugar in beets and thus to raise their value as forage-crops, with such success, that his plants have since been used for the production [93] of sugar. He must have made some choice among the numerous available sorts of beets, or chance must have placed in his hands one of the most appropriate forms. On this point however, no evidence is at hand. Since the work of Vilmorin the selection-principle has increased enormously in importance, for practical purposes as well as for the theoretical aspect of the subject. It is now being applied on a large scale to nearly all ornamental plants. It is the one great principle now in universal practice as well as one of preeminent scientific value. Of course, the main arguments of the evolution theory rest upon morphologic, systematic, geographic and paleontologic evidence. But the question as to how we can coordinate the relation between existing species and their supposed ancestors is of course one of a physiologic nature. Direct observation or experiments were not available for Darwin and so he found himself constrained to make use of the experience of breeders. This he did on a broad scale, and with such success that it was precisely this side of his arguments that played the major part in convincing his contemporaries. The work of the breeders previous to Darwin's time had not been very critically performed. Recent analyses of the evidence obtained [94] from them show that numerous types of variability were usually thrown together. What type in each case afforded the material, which the breeder in reality made use of, has only been inquired into in the last few decades. Among those who have opened the way for thorough and more scientific treatment are to be mentioned Rimpau and Von Rumker of Germany and W.M. Hays of America. Von Rumker is to be considered as the first writer, who sharply distinguished between two phases of methodical breeding-selection. One side he calls the production of new forms, the other the improvement of the breed. He dealt with both methods extensively. New forms are considered as spontaneous variations occurring or originating without human aid. They have only to be selected and isolated, and their progeny at once yields a constant and pure race. This race retains its character as long as it is protected against the admixture of other minor varieties, either by cross-pollination, or by accidental seeds. Improvement, on the other hand, is the work of man. New varieties of course can only be isolated if chance offers them; the improvement is not incumbent on chance. It does not create really anything new, but develops characters, which were already existing. It brings [95] the race above its average, and must guard constantly against the regression towards this average which usually takes place. Hays has repeatedly insisted upon the principle of the choice of the most favorable varieties as the foundation for all experiments in improving races. He asserts that half the battle is won by choosing the variety which is to serve as a foundation stock, while the other half depends upon the selection of parent-plants within the chosen variety. Thus the choice of the variety is the first principle to be applied in every single case; the so-called artificial selection takes only a secondary place. Calling all minor units within the botanic species by the common name of varieties, without regard to the distinction between elementary species and retrograde varieties, the principle is designated by the term of "variety-testing." This testing of varieties is now, as is universally known, one of the most important lines of work of the agricultural experiment stations. Every state and every region, in some instances even the larger farms, require a separate variety of corn, or wheat, or other crops. They must be segregated from among the hundreds of generally cultivated forms, within each single botanic species. Once found, the type may be ameliorated according to the local conditions [96] and needs, and this is a question of improvement. The fact that our cultivated plants are commonly mixtures of different sorts, has not always been known. The first to recognize it seems to have been the Spanish professor of botany, Mariano Lagasca, who published a number of Spanish papers dealing with useful plants and botanical subjects between 1810 and 1830, among them a catalogue of plants cultivated in the Madrid Botanical Garden. Once when he was on a visit to Colonel Le Couteur on his farm in Jersey, one of the Channel Islands off the coast of France, in discussing the value of the fields of wheat, he pointed out to his host, that they were not really pure and uniform, as was thought at that time, and suggested the idea that some of the constituents might form a larger part in the harvest than others. In a single field he succeeded in distinguishing no less than 23 varieties, all growing together. Colonel Le Couteur took the hint, and saved the seeds of a single plant of each supposed variety separately. These he cultivated and multiplied till he got large lots of each and could compare their value. From among them he then chose the variety producing the greatest amount of the finest, whitest and most nutritious flour. This he eventually placed in the [97] market under the name of "Talavera de Bellevue." It is a tall, white variety, with long and slender white heads, almost without awns, and with fine white pointed kernels. It was introduced into commerce about 1830, and is still one of the most generally cultivated French wheats. It was highly prized in the magnificent collection of drawings and descriptions of wheats, published by Vilmorin under the title "Les meilleurs bles" and is said to have quite a number of valuable qualities, branching freely and producing an abundance of good grain and straw. It is however, sensitive to cold winters in some degree and thereby limited in its distribution. Hallett, the celebrated English wheat-breeder, tried in vain to improve the peculiar qualities of this valuable production of Le Couteur's. Le Couteur worked during many years along this line, long before the time when Vilmorin conceived the idea of improvement by race selections, and he used only the simple principle of distinguishing and isolating the members of his different fields. Later he published his results in a work on the varieties, peculiarities and classification of wheat (1843), which though now very rare, has been the basis and origin of the principle of variety-testing. The discovery of Lagasca and Le Couteur was [98] of course not applicable to the wheat of Jersey alone. The common cultivated sorts of wheat and other grains were mixtures then as they are even now. Improved varieties are, or at least should be, in most cases pure and uniform, but ordinary sorts, as a rule, are mixtures. Wheat, barley and oats are self-fertile and do not mix in the field through cross-pollination. Every member of the assemblage propagates itself, and is only checked by its own greater or less adaptation to the given conditions of life. Rimpau has dealt at large with the phenomenon as it occurs in the northern and middle parts of Germany. Even Rivett's "Bearded wheat," which was introduced from England as a fine improved variety, and has become widely distributed throughout Germany, cannot keep itself pure. It is found mingled almost anywhere with the old local varieties, which it was destined to supplant. Any lot of seed exhibits such impurities, as I have had the opportunity of observing myself in sowings in the experimental-garden. But the impurities are only mixtures, and all the plants of Rivett's "Bearded wheat," which of course constitute the large majority, are of pure blood. This may be confirmed when the seeds are collected and sown separately in cultures that can be carefully guarded. [99] In order to get a closer insight into the causes of this confused condition of ordinary races, Rimpau made some observations on Rivett's wheat. He found that it suffers from frost during winter more than the local German varieties, and that from various causes, alien seeds may accidentally, and not rarely, become mixed with it. The threshing-machines are not always as clean as they should be and may be the cause of an accidental mixture. The manure comes from stables, where straw and the dust from many varieties are thrown together, and consequently living kernels may become mixed with the dung. Such stray grains will easily germinate in the fields, where they find more congenial conditions than does the improved variety. If winter arrives and kills quantities of this latter, the accidental local races will find ample space to develop. Once started, they will be able to multiply so rapidly, that in one or two following generations they will constitute a very considerable portion of the whole harvest. In this way the awnless German wheat often prevails over the introduced English variety, if the latter is not kept pure by continuous selection. The Swiss wheat-breeder Risler made an experiment which goes to prove the certainty of the explanation given by Rimpau. He observed on his farm at Saleves near the lake of Geneva that after a lapse of time the "Galland wheat" deteriorated and assumed, as was generally believed, the characters of the local sorts. In order to ascertain the real cause of this apparent change, he sowed in alternate rows in a field, the "Galland" and one of the local varieties. The "Galland" is a race with obvious characters and was easily distinguished from the other at the time when the heads were ripe. They are bearded when flowering, but afterwards throw off the awns. The kernels are very large and yield an extraordinarily good, white flour. During the first summer all the heads of the "Galland" rows had the deciduous awns but the following year these were only seen on half of the plants, the remainder having smooth heads, and the third year the "Galland" had nearly disappeared, being supplanted by the competing local race. The cause of this rapid change was found to be twofold. First the "Galland," as an improved variety, suffers from the winter in a far higher degree than the native Swiss sorts, and secondly it ripens its kernels one or two weeks later. At the time of harvest it may not have become fully ripe, while the varieties mixed with it had reached maturity. The wild oat, _Avena fatua_, is very common in [101] Europe from whence it has been introduced in the United States. In summers which are unfavorable to the development of the cultivated oats it may be observed to multiply with an almost incredible rapidity. It does not contribute to the harvest, and is quite useless. If no selection were made, or if selection were discontinued, it would readily supplant the cultivated varieties. From these several observations and experiments it may be seen, that it is not at all easy to keep the common varieties of cereals pure and that even the best are subject to the encroachment of impurities. Hence it is only natural that races of cereals, when cultivated without the utmost care, or even when selected without an exact knowledge of their single constituents, are always observed to be more or less in a mixed condition. Here, as everywhere with cultivated and wild plants, the systematic species consist of a number of minor types, which pertain to different countries and climates, and are growing together in the same climate and under the same external conditions. They do not mingle, nor are their differentiating characters destroyed by intercrossing. They each remain pure, and may be isolated whenever and wherever the desirability for such a proceeding should arise. The purity of [102] the races is a condition implanted in them by man, and nature always strives against this arbitrary and one-sided improvement. Numerous slight differences in characters and numerous external influences benefit the minor types and bring them into competition with the better ones. Sometimes they tend to supplant the latter wholly, but ordinarily sooner or later a state of equilibrium is reached, in which henceforth the different sorts may live together. Some are favored by warm and others by cool summers, some are injured by hard winters while others thrive then and are therefore relatively at an advantage. The mixed condition is the rule, purity is the exception. Different sorts of cereals are not always easily distinguishable by the layman and therefore I will draw your attention to conditions in meadows, where a corresponding phenomenon can be observed in a much simpler way. Only artificial pasture-grounds are seen to consist of a single species of grass or clover. The natural condition in meadows is the occurrence of clumps of grasses and some clovers, mixed up with perhaps twenty or more species of other genera and families. The numerical proportion of these constituents is of great interest, and has been studied at Rothamstead in England and on a number of other farms. It is [103] always changing. No two successive years show exactly the same proportions. At one time one species prevails, at another time one or two or more other species. The weather during the spring and summer benefits some and hurts others, the winter may be too cold for some, but again harmless for others, the rainfall may partly drown some species, while others remain uninjured. Some weeds may be seen flowering profusely during some years, while in other summers they are scarcely to be found in the same meadow. The whole population is in a fluctuating state, some thriving and others deteriorating. It is a continuous response to the ever changing conditions of the weather. Rarely a species is wholly annihilated, though it may apparently be so for years; but either from seeds or from rootstocks, or even from neighboring lands, it may sooner or later regain its foothold in the general struggle for life. This phenomenon is a very curious and interesting one. The struggle for life, which plays so considerable a part in the modern theories of evolution, may be seen directly at work. It does not alter the species themselves, as is commonly supposed, but it is always changing their numerical proportion. Any lasting change in the external conditions will of course alter the average oscillation and the influence [104] of such alterations will manifest itself in most cases simply in new numerical proportions. Only extremes have extreme effects, and the chance for the weaker sorts to be completely overthrown is therefore very small. Any one, who has the opportunity of observing a waste field during a series of years, should make notes concerning the numerical proportions of its inhabitants. Exact figures are not at all required; approximate estimates will ordinarily prove to be sufficient, if only the standard remains the same during the succeeding years. The entire mass of historic evidence goes to prove that the same conditions have always prevailed, from the very beginning of cultivation up to the present time. The origin of the cultivation of cereals is to be sought in central Asia. The recent researches of Solms Laubach show it to be highly probable that the historic origin of the wheat cultivated in China, is the same as that of the wheat of Egypt and Europe. Remains of cereals are found in the graves of Egyptian mummies, in the mounds of waste material of the lake-dwellings of Central Europe, and figures of cereals are to be seen on old Roman coins. In the sepulchre of King Ra-n-Woser of the Fifth Dynasty of Egypt, who lived about 2000 years B.C., two [105] tombs have recently been opened by the German Oriental Society. In them were found quantities of the tares of the _Triticum dicoccum_, one of the more primitive forms of wheat. In other temples and pyramids and among the stones of the walls of Dashur and El Kab studied by Unger, different species and varieties of cereals were discovered in large quantities, that showed their identity with the present prevailing cultivated races of Egypt. The inhabitants of the lake-dwellings in Switzerland possessed some varieties of cereals, which have entirely disappeared. They are distinguished by Heer under special names. The small barley and the small wheat of the lake-dwellers are among them. All in all there were ten well distinguished varieties of cereals, the Panicum and the Setaria or millet being of the number. Oats were evidently introduced only toward the very last of the lake-dwelling period, and rye is of far later introduction into western Europe. Similar results are attained by the examination of the cereals figured by the Romans of the same period. All these are archaeologic facts, and give but slight indications concerning the methods of cultivation or the real condition of the cultivated races of that time. Virgil has left us some knowledge of the requirements of methodical [106] culture of cereals of his time. In his poem _Georgics_ (I. 197) the following lines are found: _Vidi lecta din, et multo spectata labore Degenerare tamen, ni vis humana quotannis Maxima quaeque manu legeret_. (The chosen seed, through years and labor improved, Was seen to run back, unless yearly Man selected by hand the largest and fullest of ears.) Elsewhere Virgil and also some lines of Columella and Varro go to prove in the same way that selection was applied by the Romans to their cereals, and that it was absolutely necessary to keep their races pure. There is little doubt, but that it was the same principle as that which has led, after many centuries, to the complete isolation and improvement of the very best races of the mixed varieties. It further proves that the mixed conditions of the cereals was known to man at that time, although distinct ideas of specific marks and differences were of course still wholly lacking. It is proof also that cultivated cereals from the earliest times must have been built up of numerous elementary forms. Moreover it is very probable, that in the lapse of centuries a goodly number of such types must have disappeared. [107] Among the vanished forms are the special barley and wheat of the lake-dwellings, the remains of which have been accidentally preserved, but most of the forms must have disappeared without leaving any trace. This inference is supported by the researches of Solms-Laubach, who found that in Abyssinia numerous primitive types of cereals are still in culture. They are not adequate to compete with our present varieties, and would no doubt also have disappeared, had they not been preserved by such quite accidental and almost primitive isolation. Closing this somewhat long digression into history we will now resume our discussion concerning the origin of the method of selecting cereals for isolation and segregate-cultivation. Some decades after Le Couteur, this method was taken up by the celebrated breeder Patrick Sheriff of Haddington in Scotland. His belief, which was general at that time, was "That cultivation has not been found to change well defined kinds, and that improvement can be best attained by selecting new and superior varieties, which nature occasionally produces, as if inviting the husbandman to stretch forth his hand and cultivate them." Before going into the details of Sheriff's work it is as well to say something concerning [108] the use of the word "selection." This word was used by Sheriff as seen in the quotation given, and it was obviously designed to convey the same idea as the word "lecta" in the quotation from Virgil. It was a choice of the best plants from among known mixed fields, but the chosen individuals were considered to be representatives of pure and constant races, which could only be isolated, but not ameliorated. Selection therefore, in the primitive sense of the word, is the choice of elementary species and varieties, with no other purpose than that of keeping them as pure as possible from the admixture of minor sorts. The Romans attained this end only imperfectly, simply because the laws governing the struggle for life and the competition of numerous sorts in the fields were unsuspected by them. Le Couteur and Sheriff succeeded in the solution of the problem, because they had discovered the importance of isolation. The combination of a careful choice with subsequent isolation was all they knew about it, and it was one of the great achievements to which modern agriculture owes its success. The other great principle was that of Vilmorin. It was the improvement within the race, or the "amelioration of the race" as it was termed by him. It was introduced into [109] England by F.F. Hallett of Brighton in Sussex, who at once called it "pedigree-culture," and produced his first new variety under the very name of "Pedigree-wheat." This principle, which yields improved strains, that are not constant but dependent on the continued and careful choice of the best plants in each succeeding generation, is now generally called "selection." But it should always be remembered that according to the historic evolution of the idea, the word has the double significance of the distinction and isolation of constant races from mixtures, and that of the choice of the best representatives of a race during all the years of its existence. Even sugar-beets, the oldest "selected" agricultural plants, are far from having freed themselves from the necessity of continuous improvement. Without this they would not remain constant, but would retrograde with great rapidity. The double meaning of the word selection still prevailed when Darwin published his "Origin of Species." This was in the year 1859, and at that time Shirreff was the highest authority and the most successful breeder of cereals. Vilmorin's method had been applied only to beets, and Hallett had commenced his pedigree-cultures only a few years before and his first publication of the "Pedigree-wheat" [110] appeared some years later at the International Exhibition of London in 1862. Hence, whenever Darwin speaks of selection, Shirreff's use of the word may as well be meant as that of Vilmorin. However, before going deeper into such theoretical questions, we will first consider the facts, as given by Shirreff himself. During the best part of his life, in fact during the largest part of the first half of the nineteenth century, Shirreff worked according to a very simple principle. When quite young he had noticed that sometimes single plants having better qualities than the average were seen in the fields. He saved the grains, or sometimes the whole heads of such plants separately, and tried to multiply them in such manner as to avoid intermixtures. His first result was the "Mungoswell's wheat." In the spring of 1819 he observed quite accidentally in a field of the farm of that name, a single plant which attracted his attention by a deeper green and by being more heavily headed out. Without going into further details, he at once chose this specimen as the starting point of a new race. He destroyed the surrounding plants so as to give it more space, applied manure to its roots, and tended it with special care. It yielded 63 heads and nearly [111] 2500 grains. All of these were sown the following fall, and likewise in the succeeding years the whole harvest was sown in separate lots. After two years of rapid multiplication it proved to be a good new variety and was brought into commerce. It has become one of the prominent varieties of wheat in East Lothian, that county of Scotland of which Haddington is the principal borough. The grains of "Mungoswell's wheat" are whiter than those of the allied "Hunter's wheat," more rounded but otherwise of the same size acid weight. The straw is taller and stronger, and each plant produces more culms and more heads. Shirreff assumed, that the original plant of this variety was a sport from the race in which he had found it, and that it was the only instance of this sport. He gives no details about this most interesting side of the question, omitting even to tell the name of the parent variety. He only asserts that it was seen to be better, and afterwards proved so by the appreciation of other breeders and its success in trade. He observed it to be quite constant from the beginning, no subsequent selection being needed. This important feature was simply assumed by him to be true as a matter of course. [112] Some years afterwards, in the summer of 1824, he observed a large specimen of oats in one of the fields of the same farm. Being at that time occupied in making a standard collection of oats for a closer comparison of the varieties, he saved the seeds of that plant and sowed them in a row in his experiment-field. It yielded the largest culms of the whole collection and bore long and heavy kernels with a red streak on the concave side and it excelled all other sorts by the fine qualities of its very white meal. In the unequal length of its stalks it has however a drawback, as the field appears thinner and more meager than it is in reality. "Hopetown oats," as it is called, has found its way into culture extensively in Scotland and has even been introduced with success into England, Denmark and the United States. It has been one of the best Scottish oats for more than half a century. The next eight years no single plant judged worthy of selection on his own farm attracted Shirreff's attention. But in the fall of 1832 he saw a beautiful plant of wheat on a neighboring farm and he secured a head of it with about 100 grains. From this he produced the "Hopetown wheat." After careful separation from the kernels this original ear was preserved, and was afterwards exhibited at the Stirling Agricultural [113] Museum. The "Hopetown wheat" has proved to be a constant variety, excelling the ordinary "Hunter's wheat" by larger grains and longer heads; it yields likewise a straw of superior quality and has become quite popular in large districts of England and Scotland, where it is known by the name of "White Hunter's" from its origin and the brilliant whiteness of its heads. In the same way Shirreff's oats were discovered in a single plant in a field where it was isolated in order to be brought into commerce after multiplication. It has won the surname of "Make-him-rich." Nothing is on record about the details of its origin. Four valuable new varieties of wheat and oats were obtained in this way in less than forty years. Then Shirreff changed his ideas and his method of working. Striking specimens appeared to be too rare, and the expectation of a profitable result too small. Therefore he began work on a larger scale. He sought and selected during the summer of 1857 seventy heads of wheat, each from a single plant showing some marked and presumably favorable peculiarity. These were not gathered on one field, but were brought together from all the fields to which he had access in his vicinity. The grains of each of these selected heads were [114] sown separately, and the lots compared during their whole life-period and chiefly at harvest time. Three of the lots were judged of high excellence, and they alone were propagated, and proving to be constant new varieties from the outset were given to the trade under the names of "Shirreff's bearded white," "Shirreff's bearded red," and "Pringle's wheat." They have found wide acceptance, and the first two of them are still considered by Vilmorin as belonging to the best wheats of France. This second method of Shirreff evidently is quite analogous to the principle of Lagasca and Le Couteur. The previous assumption that new varieties with striking features were being produced by nature from time to time, was abandoned, and a systematic inquiry into the worth of all the divergent constituents of the fields was begun. Every single ear at once proved to belong to a constant and pure race, but most of these were only of average value. Some few however, excelled to a degree, which made them worth multiplying, and to be introduced into trade as separate varieties. Once started, this new method of comparison, selection and isolated multiplication was of course capable of many improvements. The culture in the experiment-field was improved, so as to insure a fuller and more rapid growth. [115] The ripe heads had to be measured and counted and compared with respect to their size and the number of their kernels. Qualities of grain and of meal had to be considered, and the influence of climate and soil could not be overlooked. Concerning the real origin of his new types Shirreff seems never to have been very inquisitive. He remarks that only the best cultivated varieties have a chance to yield still better types, and that it is useless to select and sow the best heads of minor sorts. He further remarks that it is not probable that he found a new sport every time; on the contrary he assumes that his selections had been present in the field before, and during a series of succeeding generations. How many years old they were, was of course impossible to determine. But there is no reason to believe that the conditions in the fields of Scotland were different from those observed on the Isle of Jersey by Le Couteur. In the year 1862 Shirreff devoted himself to the selection of oats, searching for the best panicles from the whole country, and comparing their offspring in his experimental garden. "Early Fellow," "Fine Fellow," "Longfellow" and "Early Angus" are very notable varieties introduced into trade in this way. [116] Some years later Patrick Shirreff described his experiments and results in a paper entitled, "On the improvement of cereals," but the descriptions are very short, and give few details of systematic value. The leading principle, however, is clearly indicated, and anyone who studies with care his method of working, may confidently attempt to improve the varieties of his own locality in the same way. This great principle of "variety-testing," as it has been founded by Le Couteur and Patrick Shirreff, has increased in importance ever since. Two main features are to be considered here. One is the production of local races, the other the choice of the best starting-point for hybridizing experiments, as is shown in California by the work of Luther Burbank in crossing different elementary species of _Lilium pardalinum_ and others. Every region and locality has its own conditions of climate and soil. Any ordinary mixed race will contain some elementary forms which are better adapted to a given district, while others are more suitable to divergent conditions. Hence it can readily be inferred that the choice cannot be the same for different regions. Every region should select its own type from among the various forms, and variety testing therefore becomes a task which every [117] one must undertake under his own conditions. Some varieties will prove, after isolation, to be profitable for large districts and perhaps for whole states. Others will be found to be of more local value, but in such localities to excel all others. As an example we may take one of the varieties of wheat originated by the Minnesota Experiment Station. Hays described it as follows. It was originated from a single plant. From among 400 plants of "Blue stem" several of the best were chosen, each growing separately, a foot apart in every direction. Each of the selected plants yielded 500 or more grains of wheat, weighing 10 or more grams. The seeds from these selected plants were raised for a few years until sufficient was obtained to sow a plot. Then for several years the new strains were grown in a field beside the parent-variety. One of them was so much superior that all others were discarded. It was the one named "Minnesota No. 169." For a large area of Minnesota this wheat seems capable of yielding at least 1 or 2 bushels more grain per acre than its parent variety, which is the best kind commonly and almost universally found on the farms in southern and central Minnesota. It would be quite superfluous for our present purpose to give more instances. The fact of [118] the compound nature of so-called species of cultivated plants seems to be beyond all doubt, and its practical importance is quite obvious. Acclimatization is another process, which is largely dependent on the choice of adequate varieties. This is shown on a large scale by the slow and gradual dispersion of the varieties of corn in this country. The largest types are limited to temperate and subtropical regions, while the varieties capable of cultivation in more northern latitudes are smaller in size and stature and require a smaller number of days to reach their full development from seed to seed. Northern varieties are small and short lived, but the "Forty-day-corn" or "Quarantino maize" is recorded to have existed in tropical America at the time of Columbus. In preference, or rather to the entire exclusion of taller varieties, it has thriven on the northern boundaries of the corn-growing states of Europe since the very beginning of its cultivation. According to Naudin, the same rule prevails with melons, cucumbers and gherkins, and other instances could easily be given. Referring now to the inferences that may be drawn from the experience of the breeders in order to elucidate the natural processes, we will return to the whitlow-grasses and pansies. [119] Nature has constituted them as groups of slightly different constant forms, quite in the same way as wheat and oats and corn. Assuming that this happened ages ago somewhere in central Europe, it is of course probable that the same differences in respect to the influence of climatic conditions will have prevailed as with cereals. Subsequent to the period which has produced the numerous elementary species of the whitlow-grass came a period of widespread distribution. The process must have been wholly comparable with that of acclimatization. Some species must have been more adapted to northern climates, others to the soils of western or eastern regions and so on. These qualities must have decided the general lines of the distribution, and the species must have been segregated according to their respective climatic qualities, and their adaptability to soil and weather. A struggle for life and a natural selection must have accompanied and guided the distribution, but there is no reason to assume that the various forms were changed by this process, and that we see them now endowed with other qualities than they had at the outset. Natural selection must have played, in this and in a large number of other cases, quite the same part as the artificial method of variety testing. [120] Indeed it may be surmised that this has been its chief and prominent function. Taking up again our metaphor of the sieve we can assert that in such cases climate and soil exercise sifting action and in this way the application of the metaphor becomes more definite. Of course, next to the climate and soil in importance, come ecological conditions, the vegetable and animal enemies of the plants and other influences of the same nature. In conclusion it is to be pointed out that this side of the problem of natural selection and the struggle for life appears to offer the best prospects for experimental, or for continued statistical inquiry. Direct observations are possible and any comparison of numerical proportions of species in succeeding years affords clear proof of the part it plays. And above all, such observations can be made quite independently of doubtful theoretical considerations about presumed changes of character. The fact of natural selection is plain and it should be studied in its most simple conditions. [121] C. RETROGRADE VARIETIES LECTURE V CHARACTERS OF RETROGRADE VARIETIES Every one admires the luxuriance of garden-flowers, and their diversity of color and form. All parts of the world have contributed to their number and every taste can find its preference among them. New forms produced by the skill of the breeder are introduced every year. This has been done mostly by crossing and intermingling the characters of introduced species of the same genus. In some of the cases the history of our flowers is so old that their hybrid origin is forgotten, as in the case of the pansies. Hybridizations are still going on in other groups on a large scale, and new forms are openly claimed to be of hybrid origin. Breeders and amateurs generally have more interest in the results than in the way in which they have been brought about. Excellent flowers and fruit recommend themselves and there seems to be no reason for inquiring [122] about their origin. In some cases the name of the originator may be so widely known that it adds weight to the value of the new form, and therefore may advantageously be coupled with it. The origin and history of the greater part of our garden-flowers, fruits and vegetables are obscure; we see them as they are, and do not know from whence they came. The original habitat for a whole genus or for a species at large, may be known, but questions as to the origin of the single forms, of which it is built up, ordinarily remain unanswered. For these reasons we are restricted in most cases to the comparison of the forms before us. This comparison has led to the general use of the term "variety" in opposition to "species." The larger groups of forms, which are known to have been introduced as such are called species. All forms which by their characters belong to such a species are designated as varieties, irrespective of their systematic relation to the form, considered as the ancestor of the group. Hence, we distinguish between "hybrid varieties" and "pure varieties" according to their origin from different parents or from a single line of ancestors. Moreover, in both groups the forms may be propagated by seeds, or in the vegetative way by buds, by grafting or [123] by cutting, and this leads to the distinction of "seed-varieties" and "vegetative varieties." In the first case the inheritance of the special characters through the seeds decides the status of the variety, in the latter case this point is left wholly out of consideration. Leaving aside all these different types, we are concerned here only with the "seed-varieties" of pure origin, or at least with those, that are supposed to be so. Hybridization and vegetative multiplication of the hybrids no doubt occur in nature, but they are very rare, when compared with the ordinary method of propagation by seed. "Seed-varieties" may further be divided into constant and inconstant ones. The difference is very essential, but the test is not always easy to apply. Constant varieties are as sharply defined and as narrowly limited as are the best wild species, while inconstant types are cultivated chiefly on account of their wide range of form and color. This diversity is repeated yearly, even from the purest seed. We will now discuss the constant seed-varieties, leaving the inconstant and eversporting types to a subsequent lecture. In this way we may make an exact inquiry into the departures from the species which are ordinarily considered to constitute the essential character of such a constant and pure seed-variety [124] and need only compare these differences with those that distinguish the elementary species of one and the same group from each other. Two points are very striking. By far the greatest part of the ordinary garden-varieties differ from their species by a single sharp character only. In derivative cases two, three or even more such characters may be combined in one variety, for instance, a dwarfed variety of the larkspur may at the same time bear white flowers, or even double white flowers, but the individuality of the single characters is not in the least obscured by such combinations. The second point is the almost general occurrence of the same variety in extended series of species. White and double flowers, variegated leaves, dwarfs and many other instances may be cited. It is precisely this universal repetition of the same character that strikes us as the essential feature of a variety. And again these two characteristics may now be considered separately. Let us begin with the sharpness of the varietal characters. In this respect varieties differ most obviously from elementary species. These are distinguished from their nearest allies in almost all organs. There is no prominent distinctive feature between the single forms of _Draba_ [125] _Verna_, _Helianthemum_ or of _Taraxacum_; all characters are almost equally concerned. The elementary species of _Draba_ are characterized, as we have seen, by the forms and the hairiness of the leaves, the number and height of the flower-stalks, the breadth and incision of the petals, the forms of the fruits, and so on. Every one of the two hundred forms included in this collective species has its own type, which it is impossible to express by a single term. Their names are chosen arbitrarily. Quite the contrary is the case with most of the varieties, for which one word ordinarily suffices to express the whole difference. White varieties of species with red or blue flowers are the most common instances. If the species has a compound color and if only one of the constituents is lost, partially colored types arise as in _Agrostemma Coronaria bicolor_. Or the spots may disappear and the color become uniform as in _Gentiana punctata concolor_ and the spotless Arum or _Arum maculatum immaculatum_. Absence of hairs produces forms as _Biscutella laevigata glabra_; lack of prickles gives the varieties known as _inermis, as for instance, _Ranunculus arvensis inermis_. _Cytisus prostratus_ has a variety _ciliata_, and _Solanum Dulcamara_, or the bitter-sweet, has a variety called _tomentosum_. The curious monophyllous [126] variety of the strawberry and many other forms will be discussed later. To enlarge this list it would only be necessary to extract from a flora, or from a catalogue of horticultural plants, the names of the varieties enumerated therein. In nearly every instance, where true varieties and not elementary species are concerned, a single term expresses the whole character. Such a list would also serve to illustrate the second point since the same names would recur frequently. Long lists of varieties are called alba, or inermis, or canescens or lutea, and many genera contain the same appellations. In some instances the systematists use a diversity of names to convey exactly the same idea, as if to conceal the monotony of the character, as for instance in the case of the lack of hairs, which is expressed by the varietal names of _Papaver dubium glabrum_, _Arabis ciliata glabrata_, _Arabis hirsuta glaberrima_, _Veronica spicata nitens_, _Amygdalus persica laevis_, _Paeonia corallina Leiocarpa_, &c. On the contrary we find elementary species in different genera based on the greatest possible diversity of features. The forms of _Taraxacum_ or _Helianthemum_ do not repeat those of _Draba_ or _Viola_. In roses and brambles the distinguishing features are characteristic of the type, as [127] they are evidently derived from it and limited to it. And this is so true that nobody claims the grade of elementary species for white roses or white brambles, but everyone recognizes that forms diverging from the nearest species by a single character only, are to be regarded as varieties. This general conviction is the basis on which we may build up a more sharply defined distinction between elementary species and varieties. It is an old rule in systematic botany, that no form is to be constituted a species upon the basis of a single character. All authors agree on this point; specific differences are derived from the totality of the attributes, not from one organ or one quality. This rule is intimately connected with the idea that varieties are derived from species. The species is the typical, really existing form from which the variety has originated by a definite change. In enumerating the different forms the species is distinguished by the term of genuine or typical, often only indicated as _a_ or the first; then follow the varieties sometimes in order of their degree of difference, sometimes simply in alphabetical order. In the case of elementary species there is no real type; no one of them predominates because all are considered to be equal in rank, and the systematic species to which they [128] are referred is not a really existing form, but is the abstraction of the common type of all, just as it is in the case of a genus or of a family. Summarizing the main points of this discussion, we find that elementary species are of equal rank and together build up the collective or systematic ideal species. Varieties on the other hand are derived from a real and commonly, still existing type. I hope that I have succeeded in showing that the difference between elementary species, or, as they are often called, smaller or subspecies, on the one hand and varieties on the other, is quite a marked one. However, in order to recognize this principle it is necessary to limit the term variety, to those propagating themselves by seed and are of pure and not of hybrid origin. But the principle as stated here, does not involve an absolute contrast between two groups of characters. It is more a difference in our knowledge and appreciation of them than a difference in the things themselves. The characters of elementary species are, as a rule, new to us, while those of varieties are old and familiar. It seems to me that this is the essential point. And what is it that makes us familiar with them? Obviously the continuous recurrence of the same changes, because by a constant repetition they must of course lose their novelty. [129] Presently we shall look into these characters more in detail and then we shall find that they are not so simple as might be supposed at first sight; but precisely because we are so familiar with them, we readily see that their different features really belong to a single character; while in elementary species everything is so new that it is impossible for us to discern the unities of the new attributes. If we bear in mind all these difficulties we cannot wonder at the confusion on this question that seems to prevail everywhere. Some authors following Linnaeus simply call all the subdivisions of species, varieties; others follow Jordan and avoid the difficulty by designating all smaller forms directly as species. The ablest systematists prefer to consider the ordinary species as collective groups, calling their constituents "The elements of the species," as was done by A.P. De Candolle, Alph. De Candolle and Lindley. By this method they clearly point out the difference between the subdivisions of wild species as they ordinarily occur, and the varieties in our gardens, which would be very rare, were they not singled out and preserved. Our familiarity with a character and our grounds for calling it an old acquaintance may result from two causes, which in judging a new [130] variety are essentially different. The character in question may be present in the given species or it may be lacking, but present in the other group. In the first case a variety can only be formed by the loss of the character, in the second case it arises by the addition of a new one. The first mode may be called a negative process, while the second is then to be designated as positive. And as it is more easy to lose what one has than to obtain something new, negative varieties are much more common than are positive ones. Let us now take an instance of a character that is apt to vary in both ways, for this is obviously the best way of making clear what is meant by a negative and a positive change. In the family of the composites we find a group of genera with two forms of florets on each flower-head. The hermaphrodite ones are tubular with 5, or rarely 4, equal teeth, and occupy the center of the head. These are often called the flosculous florets or disk-florets. Those of the circumference are ligulate and ordinarily unisexual, without stamens. In many cases they are sterile, having only an imperfect ovary. They are large and brightly colored and are generally designated as ray-florets. As instances we may cite the camomile (_Anthemis nobilis_), the wild camomile (_Matricaria Chamomilla_), [131] the yarrow (_Achillea Millefolium_), the daisies, the Dahlia and many others. Species occur in this group of plants from time to time that lack the ray-florets, as in the tansy (_Tanacetum vulgare_) and some _artemisias_. And the genus of the marigolds or _Bidens_ is noted for containing both of these types. The smaller and the three-toothed marigold (_B. cernua_ and _B. tripartita_) are very common plants of wet soil and swamps, ordinarily lacking the ray-florets, and in some countries they are very abundant and wholly constant in this respect, never forming radiate flower-heads. On the other hand the white-flowered and the purple marigold (_B. leucantha_ and _B. atropurpurea_) are cultivated species of our gardens, prized for their showy flower-heads with large white or deeply colored, nearly black-purple florets. Here we have opportunity to observe positive and negative varieties of the same character. The smaller, and the three-toothed marigold occur from time to time, provided with ray florets, showing a positive variation. And the white marigold has produced in our gardens a variety without rays. Such varieties are quite constant, never returning to the old species. Positive and negative varieties of this kind are by no means rare among the compositae. [132] In systematic works the positive ones are as a rule called "radiate," and the negative ones "discoid." Discoid forms of the ordinary camomile, of the daisy, of some asters (_Aster Tripolium_), and of some centauries have been described. Radiate forms have been observed in the tansy (_Tanacetum vulgare_), the common horse-weed or Canada fleabane (_Erigeron canadensis_) and the common groundsel (_Senecio vulgaris_). Taken broadly the negative varieties seem to be somewhat more numerous than the positive ones, but it is very difficult to come to a definite conclusion on this point. Quite the contrary is the case with regard to the color-varieties of red and blue flowers. Here the loss of color is so common that every one could give long lists of examples of it. Linnaeus himself supposed that no blue or red-colored wild species would be without a white variety. It is well known that he founded his often criticized prescript never to trust to color in recognizing or describing a species, on this belief. On the other hand there are some red varieties of white-flowered species. But they are very rare, and little is known about their characters or constancy. Blue varieties of white species are not found. The yarrow (_Achillea Millefolium_) has a red-flowered form, which occurs [133] from time to time in sunny and sandy localities. I have isolated it and cultivated it during a series of years and during many generations. It is quite true to its character, but the degree of its coloring fluctuates between pink and white and is extremely variable. Perhaps it can be considered as an inconstant variety. A redflowered form of the common _Begonia semperflorens_ is cultivated under the name of "Vernon," the white hawthorn (_Crataegus Oxyacantha_) is often seen with red flowers, and a pink-flowered variety of the "Silverchain" or "Bastard acacia" (_Robinia Pseud-Acacia_) is not rarely cultivated. The "Crown" variety of the yellow wall-flower and the black varieties, are also to be considered as positive color variations, the black being due in the latter cases to a very great amount of the red pigment. Among fruits there are also some positive red varieties of greenish or yellowish species, as for instance the red gooseberry (_Ribes Grossularia_) and the red oranges. The red hue is far more common in leaves, as seen among herbs, in cultivated varieties of _Coleus_ and in the brown leaved form of the ordinary white clover, among trees and shrubs in the hazelnut (_Corylus_), the beech (_Fagus_), the birch (_Betula_), the barberry (_Berberis_) and many others. But though most of these forms are very ornamental and abundant [134] in parks and gardens, little is as yet known concerning the origin of their varietal attributes and their constancy, when propagated by seeds. Besides the ray-florets and the colors, there are of course a great many other characters in which varieties may differ from their species. In most of the cases it is easy to discern whether the new character is a positive or a negative one. And it is not at all necessary to scrutinize very narrowly the list of forms to become convinced that the negative form is the one which prevails nearly everywhere, and that positive aberrations are in a general sense so rare that they might even be taken for exceptions to the rule. Many organs and many qualities may be lost in the origination of a variety. In some instances the petals may disappear, as in _Nigella_, or the stamens, as in the Guelder-rose (_Viburnum Opulus_) and the _Hortensia_ and in some bulbs even the whole flowers may be wanting, as in the beautiful "Plumosa" form of the cultivated grape-hyacinth or _Muscari comosum_. Fruits of the pineapples and bananas without seeds are on record as well as some varieties of apples and pears, of raisins and oranges. And some years ago Mr. Riviere of Algeria described a date growing in his garden that forms fruit without pits. The stoneless plum of Mr. [135] Burbank of Santa Rosa, California, is also a very curious variety, the kernel of which is fully developed but naked, no hard substance intervening between it and the pulp. More curious still are the unbranched varieties consisting of a single stem, as may be seen sometimes in the corn or maize and in the fir. Fir-trees of some three or four meters in height without a single branch, wholly naked and bearing leaves only on the shoots of the last year's growth at the apex of the tree, may be seen. Of course they cannot bear seed, and so it is with the sterile maize, which never produces any seed-spikes or staminate flowers. Other seedless varieties can be propagated by buds; their origin is in most cases unknown, and we are not sure as to whether they should be classified with the constant or with the inconstant varieties. A very curious loss is that of starch in the grains of the sugar-corn and the sugar-peas. It is replaced by sugar or some allied substance (dextrine). Equally remarkable is the loss of the runners in the so-called "Gaillon" strawberries. Among trees the pendulous or weeping, and the broomlike or fastigiate forms are very marked varieties, which occur in species belonging to quite different orders. The ash, the beach, some willows, many other trees and some [136] finer species of garden-plants, as _Sophora japonica_, have given rise to weeping varieties, and the yew-tree or _Taxus_ has a fastigiate form which is much valued because of its ascending branches and pyramidal habit. So it is with the pyramidal varieties of oaks, elms, the bastard-acacia and some others. It is generally acknowledged that these forms are to be considered as varieties on the ground of their occurrence in so wide a range of species, and because they always bear the same attributes. The pendulous forms owe their peculiarity to a lengthening of the branches and a loss of their habit of growing upwards; they are too weak to retain a vertical position and the response to gravity, which is ordinarily the cause of the upright growth, is lacking in them. As far as we know, the cause of this weeping habit is the same in all instances. The fastigiate trees and shrubs are a counterpart of the weeping forms. Here the tendency to grow in a horizontal direction is lacking, and with it the bilateral and symmetric structure of the branches has disappeared. In the ordinary yew-tree the upright stem bears its needles equally distributed around its circumference, but on the branches the needles are inserted in two rows, one to the left and one to the right. All the needles turn their upper surfaces upwards, [137] and their lower surfaces downwards, and all of them are by this means placed in a single horizontal plane, and branching takes place in the same plane. Evidently this general arrangement is another response to gravity, and it is the failure of this reaction which induces the branches to grow upwards and to behave like stems. Both weeping and fastigiate characters are therefore to be regarded as steps in a negative direction, and it is highly important that even such marked departures occur without transitions or intermediate forms. If these should occur, though ever so rarely, they would probably have been brought to notice, on account of the great prospect the numerous instances would offer. The fact that they are lacking, proves that the steps, though apparently great, are in reality to be considered as covering single units, that cannot be divided into smaller parts. Unfortunately we are still in the dark as to the question of the inheritance of these forms, since in most cases it is difficult to obtain pure seed. We now consider the cases of the loss of superficial organs, of which the nectarines are example. These are smooth peaches, lacking the soft hairy down, that is a marked peculiarity of the true peaches. They occur in different [138] races of the peach. As early as the beginning of the past century, Gallesio described no less than eight subvarieties of nectarines, each related to a definite race of peach. Most of them reproduce themselves truly from seed, as is well known in this country concerning the clingstones, freestones and some other types. Nectarines have often varied, giving rise to new sorts, as in the case of the white nectarine and many others differing greatly in appearance and flavor. On the other hand it is to be remarked, that the trees do not differ in other respects and cannot be distinguished while young, the varietal mark being limited to the loss of the down on the fruit. Peaches have been known to produce nectarines, and nectarines to yield true peaches. Here we have another instance of positive and negative steps with reference to the same character, but I cannot withhold an expression of some doubt as to the possibility of crossing and subsequently splitting up of the hybrids as a more probable explanation of at least some of the cases quoted by various writers. Smooth or glabrous varieties often occur, and some of them have already been cited as instances of the multiplication of varietal names. Positive aberrations are rather rare, and are mostly restricted to a greater density of the [139] pubescence in some hairy species, as in _Galeopsis Ladanum canescens_, _Lotus corniculatus hirsutus_ and so on. But _Veronica scutellata_ is smooth and has a pubescent variety, and Cytisus prostratus and _C. spinescens_ are each recorded to have a ciliate form. Comparable with the occurrence and the lack of hairs, is the existence or deficiency of the glaucous effect in leaves, as is well known in the common _Ricinus_. Here the glaucous appearance is due to wax distributed in fine particles over the surface of the leaves, and in the green variety this wax is lacking. Other instances could be given as in the green varieties of _Papaver alpinum_ and _Rumex scutatus_. No positive instances are recorded in this case. Spines and prickles may often disappear and give rise to unarmed and defenceless types. Of the thorn-apples both species, the whiteflowered _Datura Stramonium_ and the purple _D. Tatula_ have such varieties. Spinach has a variety called the "Dutch," which lacks the prickles of the fruit; it is a very old form and absolutely constant, as are also the thornless thorn-apples. Last year a very curious instance of a partial loss of prickles was discovered by Mr. Cockerell of East Las Vegas in New Mexico. It is a variety of the American cocklebur, often called sea-burdock, or the [140] hedgehog-burweed, a stout and common weed of the western states. Its Latin name is _Xanthium canadense_ or _X. commune_ and the form referred to is named by Mr. Cockerell, _X. Wootoni_, in honor of Professor E.o. Wooton who described the first collected specimens. The burs of the common species are densely covered with long prickles, which are slightly hooked at the apex. In the new form, which is similar in all other respects to the common cocklebur, the burs are more slender and the prickles much less numerous, about 25 to the bur and mostly stouter at the base. It occurs abundantly in New Mexico, always growing with the common species, and seems to be quite constant from seed. Mr. Cockerell kindly sent me some burs of both forms, and from these I raised in my garden last year a nice lot of the common, as well as of the _Wootoni_ plants. Spineless varieties are recorded for the bastard-acacia, the holly and the garden gooseberry (_Ribes Grossularia_, or _R. Uva-crispa_). A spineless sport of the prickly Broom (_Ulex europaeus_) has been seen from time to time, but it has not been propagated. Summarizing the foregoing facts, we have excellent evidence of varieties being produced either by the loss of some marked peculiarity or by the acquisition of others that are already [141] present in allied species. There are a great many cases however, in which the morphologic cause of the dissimilarity is not so easily discerned. But there is no reason to doubt that most of them will be found to conform to the rule on closer investigation. Therefore we can consider the following as the principal difference between elementary species and varieties; that the first arise by the acquisition of entirely new characters, and the latter by the loss of existing qualities or by the gain of such peculiarities as may already be seen in other allied species. If we suppose elementary species and varieties originated by sudden leaps or mutations, then the elementary species have mutated in the line of progression, some varieties have mutated in the line of retrogression, while others have diverged from their parental types in a line of depression, or in the way of repetition. This conception agrees quite well with the current idea that in the building up of the vegetable kingdom according to the theory of descent, it is species that form the links of the chain from the lower forms to the more highly organized later derivatives. Otherwise expressed, the system is built up of species, and varieties are only local and lateral, but never of real importance for the whole structure. [142] Heretofore we have generally assumed, that varieties differ from the parent-species in a single character only, or at least that only one need be considered. We now come to the study of those varieties, which differ in more than one character. Of these there are two types. In the first the points of dissimilarity are intimately connected with one another, in the second they are more or less independent. The mutually related peculiarities may be termed correlative, and we therefore speak, in such cases, of correlative variability. This phenomenon is of the highest importance and is of general occurrence. But before describing some examples, it is as well to note that in the lecture on fluctuating variability, cases of a totally different nature will be dealt with, which unfortunately are designated by the same term. Such merely fluctuating variations are therefore to be left out of the present discussion. The purple thorn-apple, which is considered by some writers as a variety of the white-flowered species or _Datura Stramonium_, and by others as a separate species, _D. Tatula_, will serve as an illustration. But as its distinguishing attributes, as far as we are concerned with them here, are of the nature described above as characteristic of varietal peculiarities no objection [143] can be made to our using them as a case of correlative variability. The essential character of the purple thornapple lies in the color of the flowers, which are of a very beautiful pale blue. But this color is not limited to the corolla. It is also to be seen in the stems and in the stalks and veins of the leaves, which are stained with a deep purple, the blue color being added to the original green. Even on the surface of the leaves it may spread into a purplish hue. On the stems it is to be met with everywhere, and even the young seedlings show it. This is of some importance, as the young plants when unfolding their cotyledons and primary leaves, may be distinguished by this means from the seedlings of the white flowered species. In crossing experiments it is therefore possible to distinguish the whites and the blues, even in young seedlings, and experience shows that the correlation is quite constant. The color can always be relied upon; if lacking in the seedlings, it will be lacking in the stems and flowers also; but if the axis of the young plant is ever so slightly tinged, the color will show itself in its beauty in the later stages of the life of the plant. This is what we term correlation. The colors of the different organs are always in agreement. It is true that they require the concurrence of [144] light for development, and that in the dark or in a faint light the seedlings are apt to remain green when they should become purple, but aside from such consideration all organs always come true to their color, whether pure green and white, or whether these are combined with the blue tinge. This constancy is so absolute that the colors of the different organs convey the suggestion, that they are only separate marks of a single character. It is on this suggestion that we must work, as it indicates the cause of the correlation. Once present, the faculty of producing the anthocyan, the color in question, will come into activity wherever and whenever opportunity presents itself. It is the cell-sap of the ordinary cell tissue or parenchyma, which is colored by the anthocyan, and for this reason all organs possessing this tissue, may exhibit the color in question. Thus the color is not a character belonging to any single organ or cell, nor is it bound to a morphologic unit; it is a free, physiologic quality. It is not localized, but belongs to the entire plant. If we wish to assume for its basis material representative particles, these particles must be supposed to be diffused throughout the whole body of the plant. This conception of a physiologic unit as the [145] cause of colors and other qualities is evidently opposed to the current idea of the cells and tissues as the morphologic units of the plants. But I do not doubt, that in the long run it will recommend itself as much to the scientist as to the breeder. For the breeder, when desiring to keep his varieties up to their standard, or when breeding to a definite idea, obviously keeps his standard and his ideal for the whole plant, even if he breeds only for flowers or for fruit. I have chosen the color of the purple thornapple as a first example, but the colors of other plants show so many diverging aspects, all pointing so clearly to the same conclusion, that it would be well to take a more extensive view of this interesting subject. First we must consider the correlation in the colors of flowers and fruits. If both are colored in the species, whether red or brown or purple or nearly black, and a variety lacking this hue is known, it will be lacking in both organs. If the color is pure, the flowers and berries will become white, but such cases are rare. Ordinarily a yellowish or greenish tinge underlies the ornamental color, and if this latter disappears, the yellowish ground will become manifest. So for instance in the Belladonna, a beautiful perennial herb with great shiny black, but very poisonous, fruits. Its flowers are brown, but in [146] some woods a variety with greenish flowers and bright yellow berries occurs, which is also frequently seen in botanic gardens. The anthocyan dye is lacking in both organs, and the same is the case with the stems and the leaves. The lady's laurel or _Daphne Mezereum_ has red corollas, purple leaves and red fruits; its white flowered variety may be distinguished by lack of the red hue in the stems and leaves, and by their beautiful yellow berries. Many other instances could be given, since the loss of color in berries is a very common occurrence, so common that for instance, in the heath-family or Ericaceae, with only a few exceptions, all berry-bearing species have white-fruited varieties. The same correlation is observed in the seeds. The white-flowered flax may be seen to yield yellow and not brown seeds as in the blue species. Many varieties of flowers may be recognized by the color of their seeds, as in the poppies, stocks and others. Other white-flowered varieties may be distinguished when germinating, their young axes being of a pure instead of a purplish green. It is a test ordinarily used by gardeners, to purify their flower beds long before the blooming time, when thinning or weeding them. Even in wild plants, as in _Erodium_, _Calluna_, _Brunella_ and others, a botanist may recognize the rare white-flowered [147] variety by the pure green color of the leaves, at times when it is not in flower. Some sorts of peas bear colored flowers and a red mark on the stipules of their leaves. Among bulbous plants many varieties may be recognized even in the dry bulbs by the different tinges of the outer scales. Leaving the colors, we come now to another instance of correlation, which is still more astonishing. For it is as rare, as color-varieties are common. It is afforded by some plants the leaves of which, instead of being entire or only divided into large parts, are cleft to a greater extent by repeated fissures of the marginal lobes. Such foliar variations are often seen in gardens, where they are cultivated for their beauty or singularity, as the laciniated alders, fern-leaved, beeches and limes, oakleaved laburnums, etc. Many of them are described under the varietal name of _laciniata_. In some cases this fissure extends to the petals of the flowers, and changes them in a way quite analogous to the aberrancy of the leaves. This is known to occur with a variety of brambles, and is often seen in botanic gardens in one of the oldest and most interesting of all anomalies, the laciniated variety of the greater celandine or _Chelidonium majus_. Many other instances could be given. Most of them belong to the [148] group of negative variations, as we have defined them. But the same thing occurs also with positive varieties, though of course, such cases are very rare. The best known instance is that of the ever-flowering begonia, _Begonia semperflorens_, which has green leaves and white flowers, but which has produced garden varieties with a brown foliage and pink flowers. Here also the new quality manifests itself in different organs. Enough has now been said on correlative changes, to convince us that they are as a rule to be considered as the expression of some general internal or physiologic quality, which is not limited to a single organ, but affects all parts of the organism, provided they are capable of undergoing the change. Such characters are therefore to be considered as units, and should be referred to the group of single characters. Opposed to these are the true compound characters, which consist of different units. These may be segregated by the production of varieties, and thereby betray the separate factors of the complex group. The most beautiful instances of such complex characters are offered by the colors of some of the most prized garden-flowers. Rarely these are of a single hue, often two or three shades contribute to the effect, and in some cases special [149] spots or lines or tracings are to be seen on a white or on a colored background. That such spots and lines are separate units is obvious and is demonstrated by the fact that sometimes spotless varieties occur, which in all other respects have kept the colors of the species. The complexity of the color is equally evident, whenever it is built up of constituents of the anthocyan and of the yellow group. The anthocyan dye is limited to the sap-cavity of the cells, while the yellow and pure orange colors are fixed in special organs of the protoplasm. The observation under the microscope shows at once the different units, which though lying in the same cell and in almost immediate vicinity of each other are always wholly separated from one another by the wall of the vacuole or sapfilled cell-cavity. The combination of red and yellow gives a brown tinge, as in the cultivated wall-flower, or those bright hues of a dark orange-red, which are so much sought in tulips. By putting such flowers for a short time in boiling water, the cells die and release the red pigment, which becomes diffused in the surrounding fluids and the petals are left behind with their yellow tinge. In this way it is easy to separate the constituents, and demonstrate the compound nature of the original colors. [150] But the diversity of the color patterns is far from being exhausted with these simple instances. Apart from them, or joined to them, other complications are frequently seen, which it is impossible to analyze in such an artificial way. Here we have to return to our former principle, the comparison of different varieties. Assuming that single units may be lost, irrespective of the others, we may expect to find them segregated by variation, wherever a sufficiently wide range of color-varieties is in cultivation. In fact, in most cases a high degree of dissimilarity may be reached in the simplest way by such a separation of the components, and by their combination into most diverse smaller groups. A very nice instance of such an analysis of flower-colors is afforded by the ordinary snapdragon. The beautiful brown red color of this common garden-plant is composed on one side of yellow elements, on the other of red units. Of the yellow there are two, one staining the whole corolla with a light hue, as is to be seen in the pure yellow variety called _luteum. This form has been produced by the loss of the whole group of the red constituents. If the yellow tinge is also lost, there arises a white variety, but this is not absolutely colorless, but shows the other yellow constituent. This last stains only some small parts [151] of the lips of the flower around the throat, brightening, as it seems, the entrance for the visiting insects. In many of the red or reddish varieties this one yellow patch remains, while the general yellow hue fails. In the variety called "Brilliant" the yellow ground makes the red color more shiny, and if it is absent the pure carmine tinge predominates. It is readily seen, that in the ordinary form the lips are of a darker red than the tube. This evident dissimilarity indicates some complexity. And in fact we have two varieties which exhibit the two causes of this attribute separately. One of them is called "Delila," and has the red color limited to the lips, whilst the tube is pure white. The other is called "Fleshy," and is of a pale pink throughout the whole corolla. Adding these two units to one another, we get the original dark red of the wild type, and it may be briefly stated here, that the way of effecting such an addition is given us in the crossing of the "Fleshy" and the "Delila" variety, the hybrid showing the two colors and returning thereby to the old prototype. Other cases of compound flower colors or of color patterns might be given as in the _Mimulus_ and the poppy, and in most of these cases some varieties are to be seen in our gardens which show only the single constituents of the group. [152] Many dark flowers have an intermediate bright hued form besides the white variety, as in the case of roses, asters, _Nicandra_ and so on. Intermediate forms with respect to stature may also be seen. The opium-poppy, the snapdragon, peas, the _Nicandra_, and many other garden-plants have not only dwarf varieties, but also some of intermediate height. These, though they are intermediate between the tall and dwarf types, cannot be considered as transitions, as between them and the extremes, intermediates are, as a rule wholly lacking. Instances of the same occurrence of three types may be seen in the seeds of maize ("Cuzco," "Horse-dent" and "Gracillima") of beans and some other plants. The _Xanthium Wootoni_, above referred to, with only part of the prickles of Xanthium commune is also a very curious instance of the demonstration of the compound nature of a character. Summarizing the conclusions that may be drawn from the evidence given in this lecture, we have seen that varieties differ from elementary species in that they do not possess anything really new. They originate for the greater part in a negative way, by the apparent loss of some quality, and rarely in a positive manner by acquiring a character, already seen in allied species. These characters are not of the nature of [153] morphologic entities, but are to be considered as physiologic units, present in all parts of the organisms, and manifesting themselves where ever occasion is afforded. They are units in the sense that they may appear and disappear singly. But very often they are combined to yield compound characters, which are capable of analysis. Opportunities for such an analysis are afforded by these groups of cultivated varieties, of which some members show a single distinguishing quality, or a number of them. [154] LECTURE VI STABILITY AND REAL ATAVISM It is generally believed that varieties are principally distinguished from species by their inconstancy. This conception is derived from some special cases and transferred to others, and in its common form this belief must have originated from the confusion which exists as to the meaning of the term variety. It is true that vegetative varieties as a rule run back, when propagated by seeds; they are an obvious instance of inconstancy. In the second place we have considered the group of inconstant or sporting varieties, which of course we must exclude when studying the stability of other types. However, even these sporting varieties are unstable only to a certain degree, and in a broader sense will prove to be as true to their character as the most constant types. Having separated these two groups, which include also the wide range of hybrid forms, we may next consider only those varieties of pure origin, and ordinarily propagated by seeds, [155] which have been discussed in former chapters. Their general character lies in their fidelity to type, and in the fact that this is single, and not double, as in the sporting varieties. But the current belief is, that they are only true to their peculiarities to a certain degree, and that from time to time, and not rarely, they revert to the type from which they have arisen. Such reversion is supposed to prove that they are mere varieties, and at the same time to indicate empirically the species from which they have sprung. In the next lecture we shall examine critically the evidence on which this assumption rests. Before doing so however, it will be necessary to collate the cases in which there is no reversion at all, or in which the reversion is absent at least in experimental and pure sowings. In the present state of our knowledge it is very difficult to decide, whether or not true reversion occurs in constant varieties. If it does occur, it surely does so very rarely and only under unusual circumstances, or in particular individuals. However when such individuals are multiplied by buds and especially when they are the only representatives of their type, the reversion, though theoretically rare, will be shown by nearly every specimen of the variety. Examples of this will be given below. [156] They are generally called atavists or reversionists, but even these terms are sometimes used in a different sense. Lastly it is to be said that the empirical and experimental evidence as to the question of constancy is not as extensive as it should be. The experimental conditions are seldom described, and it is only recently that an interest in the matter has been awakened. Much remains to be done. Among other things the innumerable varieties of trees, shrubs and perennial herbs should be tested as to their constancy when grown from purely fertilized seeds. Many of them may be included among the number that sport constantly. Leaving aside the doubtful or insufficiently studied cases, we may now turn our attention to the facts that prove the absolute stability of a large number of varieties, at least as far as such completeness can be attained by experiment or observation. The best proof is afforded by the varieties which grow wild in localities where they are quite isolated from the species, and where for this reason, no possibility of crossing disturbs the significance of the proof. As one instance the rayless form of the wild camomile, or the _Matricaria Chamomilla discoidea_ may be mentioned. Many systematists have been so strongly [157] impressed with its absolute constancy and its behavior as an ordinary species, that they have elevated it, as it is called, to the rank of a species. As such it is described under the name of _Matricaria discoidea_ DC. It is remarkable for its rapid and widespread distribution, as of late years it has become naturalized in different parts of America and of Europe, where it is to be seen especially in France and in Norway. Experimentally I raised in succeeding years between 1000 and 2000 seedlings, but observed no trace of reversion, either in the strongest or in the numerous very small and weak individuals which appeared in the cultures. The tansy-ragwort or _Senecio Jacobaea_ may be chosen as a second instance. It is a perennial herb with short rootstocks and stout stems bearing numerous short-peduncled heads in large compact corymb; it multiplies itself abundantly by seeds and is very common on the sand dunes of Holland. It has two forms, differing only in the occurrence or the lack of the ray florets. But these two varieties occupy different localities and are even limited to different provinces. As far as I have been able to ascertain on numerous excursions during a series of years, they never sport, and are only intermingled on the outskirts of their habitats. The rayless form is generally considered as the [158] variety but it is quite as stable as the radiate species. The radiate varieties of marigold, quoted in a former lecture, seem to be equally constant, when growing far away from their prototypes. I sowed the seeds of a single plant of the radiate form of _Bidens cernua_, and found all of the seedlings came true, and in the next year I had from their seed between 2,000 and 3,000 flowering individuals, all equally radiate. Many species of composites have been tried, and they are all constant. On the other hand rare sports of this kind have been observed by Murr and other authors. Many kinds of vegetables and of fruits give instances of stability. White strawberries, green grapes, white currants, crisped lettuce, crisped parsley and some other crisped forms may be cited. The spinage without prickles is a widely known instance. White-flowered flax never reverts to the blue prototype, if kept pure. Sugar-peas and sugar-corn afford further instances. Strawberries without runners have come true from seed ever since their first appearance, over a hundred years ago. Many garden-varieties, the stability of which under ordinary circumstances is doubtful, because of their being sown too close to other varieties of the same species, have been tested in [159] respect to their stability by different writers and at different times. In doing this it is plain that it is very essential to be sure of the purity of the seed. Specimens must be grown in positions isolated from their allies, and if possible be pollinated artificially with the exclusion of the visits of insects. This may be done in different ways. If it is a rare species, not cultivated in the neighborhood, it is often sufficient to make sure of this fact. Pollen may be conveyed by bees from distances of some ten or twenty meters, or in rare cases from some hundred meters and more, but a greater distance is ordinarily sufficient for isolation. If the flowers fertilize themselves, as is more often the case than is generally supposed, or if it is easy to pollinate them artificially, with their own pollen or in small groups of similar individuals, the best way is to isolate them by means of close coverings. When flowering, the plants are as a rule too large to be put under bell-glasses, and moreover such coverings would keep the air moist, and cause the flower-buds to be thrown off. The best coverings are of netting, or of canvas of sufficiently wide mesh, although after a long experience I greatly prefer cages of fine iron-wire, which are put around and over the whole plant or group of plants, and fastened securely and tightly to the ground. [160] Paper bags also may be made use of. They are slipped over the flowering branches, and bound together around the twigs, thus enclosing the flowers. It is necessary to use prepared papers, in order that they may resist rain and wind. The best sort, and the one that I use almost exclusively in my fertilization-experiments, is made of parchment-paper. This is a wood-pulp preparation, freed artificially from the so-called wood-substance or lignin. Having covered the flowers with care, and having gathered the seeds free from intermixtures and if possible separately for each single individual, it only remains to sow them in quantities that will yield the greatest possible number of individuals. Reversions are supposed to be rare and small groups of seedlings of course would not suffice to bring them to light. Only sowings of many hundreds or thousands of individuals are decisive. Such sowings can be made in one year, or can be extended over a series of years and of generations. Hildebrand and Hoffman have preferred the last method, and so did Hofmeister and many others. Hildebrand sowed the white hyacinth, and the white varieties of the larkspur, the stock and the sweet pea. Hoffman cultivated the white flax and many other varieties and Hofmeister extended his sowings [161] over thirty years with the white variety of the yellow foxglove (_Digitalis parviflora_). White-flowered varieties of perennial garden plants were used in my own experiments. I bought the plants, flowered them under isolation in the way described above, gathered the seeds from each individual separately and sowed them in isolated groups, keeping many hundreds and in some cases above a thousand plants up to the time of flowering. Among them I found only one inconstant variety, the white form of the yellow columbine, _Aquilegia chrysantha_. It evidently belonged to the group of sporting varieties already referred to. All others came absolutely true to type without any exception. The species experimented with, were _Campanula persicifolia_, _Hyssopus officinalis_, _Lobelia syphilitica_, _Lychnis chalcedonica_, _Polemonium dissectum_, _Salvia sylvestris_ and some others. Tested in the same way I found the white varieties of the following annual plants also quite true: _Chrysanthemum coronarium_, _Godetia amoena_, _Linum usitatissimum_, _Phlox drummondi_, and _Silene Armeria_. To these may be added the white hemlock stork's-bill (_Erodium cicutarium album_) which grows very abundantly in some parts of my fatherland, and is easily recognizable by its pure green leaves and stems, even when not flowering. I cultivated it, in large numbers [162] during five succeeding generations, but was never able to find even the slightest indication of a reversion to the red prototype. The scarlet pimpernel or _Anagallis arvensis_ has a blue variety which is absolutely constant. Even in Britton and Brown's "Flora," which rarely enumerates varieties, it is mentioned as being probably a distinct species. Eight hundred blooming seedlings were obtained from isolated parents, all of the same blue color. The New Zealand spinage (_Tetragonia expansa_) has a greenish and a brownish variety, the red color extending over the whole foliage, including the stems and the branches. I have tried both of them during several years, and they never sported into each other. I raised more than 5,000 seedlings, from the different seeds of one lot of the green variety in succeeding years, but neither those germinating in the first year, nor the others coming into activity after two, three or four years of repose gave any sign of the red color of the original species. It is an old custom to designate intermediate forms as hybrids, especially when both the types are widely known and the intermediates rare. Many persons believe that in doing so, they are giving an explanation of the rarer forms. But since the laws of hybridism are coming to be known we shall have to break with [163] all such usages. So for instance there are numerous flowers which are of a dark red or a dark blue color, and which, besides a white variety, have a pink or a pale blue form. Such pale varieties are of exactly the same value as others, and on testing they are found to be equally stable. So for instance the pink variety of the Sweet William (_Silene Armeria rosea_), the _Clarkia pulchella carnea_ and the pale variety of the corn-cockle, called usually _Agrostemma Githago nicaeensis_ or even simply _A. nicaeensis_. The latter variety I found pure during ten succeeding generations. Another notable stable intermediate form is the poppy bearing the Danish flag (_Papaver somniferum Danebrog_). It is an old variety, and absolutely pure when cultivated separately. A long list of other instances might easily be given. Many garden-varieties, that are still universally prized and cultivated are very old. It is curious to note how often such forms have been introduced as novelties. The common foxglove is one of the best examples. It has a monstrous variety, which is very showy because it bears on the summit of its raceme and branches, large erect cup-shaped flowers, which have quite a different aspect from the normal thimbleshaped side-blossoms. These flowers are ordinarily described as belonging to the anomaly [164] known as "peloria," or regular form of a normally symmetric type; they are large and irregular on the stems and the vigorous branches but slender and quinate on the weaker twigs. Their beauty and highly interesting anomalous character has been the cause of their being described many times, and nearly always as a novelty; they have been recently re-introduced into horticulture as such, though they were already cultivated before the middle of the last century. About that time very good descriptions with plates were published in the journal "Flora" by Vrolik, but afterwards they seem to have been forgotten. The peloric variety of the foxglove always comes true from seed, though in the strict sense of the word which we have chosen for our discussion, it does not seem to be a constant and pure variety. It is very interesting to compare old botanical books, or even old drawings and engravings containing figures of anomalous plants. The celebrated Pinacothec of Munich contains an old picture by Holbein (1495-1543) representing St. Sebastian in a flower-garden. Of the plants many are clearly recognizable, and among others there is one of the "one-leaved" variety of the strawberry, which may still be met with in botanical gardens. In the year 1671 a Dutch botanist, Abraham Munting published [165] a large volume on garden-plants, containing a great number of very good engravings. Most of them of course show normal plants, but intermixed with these are varieties, that are still in cultivation and therefore must be at least two centuries old. Others, though not figured, are easily recognized by their names and descriptions. The cockscomb is the most widely known, but many white or double flowered varieties were already cultivated at that time. The striped Jalappa, the crested Sedum, the fasciated crown-imperial, white strawberries, red gooseberries and many others were known to Munting. Some varieties are as old as culture itself, and it is generally known that the Romans cultivated the white form of the opium-poppy and used the foliage of the red variety of the sugarbeet as a vegetable. In our time flowers and fruits are changing nearly as rapidly as the fancies and tastes of men. Every year new forms are introduced and usurp the place of older ones. Many are soon forgotten. But if we look at old country gardens, a goodly number of fine and valued old sorts are still to be found. It would be worth while to make special collections of living plants of old varieties, which surely would be a good and interesting work and bring about a conviction [166] of the stability of pure strains. Coming now to the other side of the question, we may consider those cases of reversion which have been recorded from time to time, and which always have been considered as direct proofs of the varietal character of the reverting form. Reversion means the falling back or returning to another type, and the word itself expresses the idea that this latter type is the form from which the variety has arisen. Some instances of atavism of this kind are well known, as they are often repeated by individuals that are multiplied by buds or by grafting. Before looking attentively into the different features of the many cases of rare reversions it will be advisable to quote a few examples. The flowering-currant of the Pacific Coast or North American scarlet ribes (_Ribes sanguineum_), a very popular ornamental shrub, will serve as a good example. It is prized because of its brilliant red racemes of flowers which blossom early in the spring, before the appearance of the leaves. From this species a white form has arisen, which is an old and widely cultivated one, but not so highly prized because of its pale flowers. These are not of a pure white, but have retained a faint reddish hue. The young twigs and the stalks of the [167] leaves afford an instance of correlated variability since in the species the red color shows itself clearly mixed with the green, while in the variety this tinge is wholly wanting. Occasionally this white-flowered currant reverts back to the original red type and the reversion takes place in the bud. One or two buds on a shrub bearing perhaps a thousand bunches of white flowers produce twigs and leaves in which the red pigment is noticeable and the flowers of which become brightly colored. If such a twig is left on the shrub, it may grow further, ramify and evolve into a larger group of branches. All of them keep true to the old type. Once reverted, the branches remain forever atavistic. It is a very curious sight, these small groups of red branches among the many white ones. And for this reason attention is often called to it, and more than once I myself have had the opportunity of noting its peculiarities. It seems quite certain that by planting such shrubs in a garden, we may rely upon seeing sooner or later some new buds reverting to the prototype. Very little attention seems hitherto to have been given to this curious phenomenon, though in many respects it deserves a closer investigation. The variety is said to have originated from seed in Scotland, many years ago, and [168] seems to be propagated only by cuttings or by grafting. If this is true, all specimens must be considered as constituting together only one individual, notwithstanding their wide distribution in the gardens and parks of so many countries. This induces me to suppose, that the tendency to reversion is not a character of the variety as such, but rather a peculiarity of this one individual. In other words it seems probable that when the whitish variety arises a second time from the red species, it is not at all necessary that it should exhibit this same tendency to revert. Or to put it still in another way, I think that we may suppose that a variety, which might be produced repeatedly from the same original stock, would only in rare individuals have a tendency to revert, and in most cases would be as absolutely constant as the species itself. Such a conception would give us a distinct insight into the cause of the rarity of these reversions. Many varieties of shrubs and trees have originated but once or twice. Most of them must therefore, if our supposition is correct, be expected to be stable and only a few may be expected to be liable to reversions. Among the conifers many very good cases of reversions by buds are to be found in gardens and glasshouses. They behave exactly like the whitish currant. But as the varietal characters [169] are chiefly found in the foliage and in the branches, these aberrations are to be seen on the plants during the whole year. Moreover they are in some cases much more numerous than in the first instance. The _Cryptomeria_ of Japan has a variety with twigs resembling ropes. This is not caused by a twisting, but only by a curvature of the needles in such a way that they seem to grow in spiral lines around the twigs. This variety often reverts to the type with widely spread, straight needles. And on many a specimen four, five, or more reverted branches may be seen on different parts of the same shrub. Still more widely cultivated is the shrub called _Cephalotaxus pedunculata fastigiata_, and more commonly known under its old name of _Podocarpus koraiana_. It is the broomlike variety of a species, nearly allied to the common American and European species of yew, (_Taxus minor_ and _T. baccata_). It is a low shrub, with broadly linear leaves of a clear green. In the species the leaves are arranged in two rows, one to the left and one to the right of the horizontally growing and widely spreading branches. In the variety the branches are erect and the leaves inserted on all sides. When sporting, it returns to the bilateral prototype and flat wings of fan-shaped twigs are produced laterally on its dense broom-like tufts. [170] Wherever this variety is cultivated the same reversion may be seen; it is produced abundantly, and even under seemingly normal circumstances. But as in the case of the _Ribes_ all the specimens are derived by buds from a single original plant. The variety was introduced from Japan about the year 1860, but is probably much older. Nothing is known as to its real origin. It never bears flowers or fruits. It is curious to note that the analogous variety of the European yew, _Taxus baccata fastigiata_, though much more commonly cultivated than the _Cephalotaxus_, never reverts, at least as far as I have been able to ascertain. This clearly corroborates the explanation given above. After considering these rare instances of more widely known reversions, we may now examine the question of atavism from a broader point of view. But in doing so it should once more be remembered, that all cases of hybridism and also all varieties sporting annually or frequently, are to be wholly excluded. Only the very rare occurrence of instances of atavism in varieties that are for the rest known to be absolutely constant, is to be considered. Atavism or reversion is the falling back to a prototype. But what is a prototype? We may take the word in a physiologic or in a systematic sense. Physiologically the signification is a [171] very narrowly restricted one; and includes only those ancestors from which a form is known to have been derived. But such evidence is of course historic. If a variety has been observed to spring from a definite species, and if the circumstances have been sufficiently ascertained not to leave the slightest doubt as to its pure origin, and if moreover all the evidence has been duly recorded, we may say that the origin of the variety is historically known. In most cases we must be content with the testimony, given somewhat later, and recorded after the new variety had the opportunity of showing its greater merits. If it now happens that such a variety of recorded origin should occasionally revert to its parent-species, we have all we can wish for, in the way of a thoroughly proved case of atavism. But such instances are very rare, as the birth of most varieties has only been very imperfectly controlled. Next to this comes the systematic relation of a variety to its species. The historic origin of the variety may be obscure, or may simply be forgotten. But the distinguishing marks are of the order described in our last lecture, either in the positive or in the negative direction, and on this ground the rarer form is considered to be a variety of the more wide-spread one. If [172] now the presumed variety sports and runs over to the presumed type, the probability of the supposed relation is evidently enhanced. But it is manifest that the explanation rests upon the results of comparative studies, and not upon direct observations of the phenomena themselves. The nearer the relations between the two types in question, the less exposed to doubt and criticism are the conclusions. But the domain of atavism is not restricted to the cases described. Quite on the contrary the facts that strike us most forcibly as being reversions are those that are apt to give us an insight into the systematic affinity of a higher degree. We are disposed to make use of them in our attempts to perfect the natural system and to remould it in such a way as to become a pedigree of the related groups. Such cases of atavism no doubt occur, but the anomalies referred to them must be interpreted merely on the ground of our assumptions as to the relative places in the system to be assigned to the different forms. Though such instances cannot be considered as belonging strictly to the subject we are dealing with, I think it may be as well to give an example, especially as it affords an occasion for referring to the highly important researches of Heinricher on the variability and atavistic [173] tendencies of the pale blue flag or _Iris pallida_. The flowers of the blue flags have a perianth of six segments united below into a tube. The three outer parts are dilated and spreading, or reflexed, while the three inner usually stand erect, but in most species are broad and colored like the outer ones. Corresponding to the outer, perianth-segments are the three stamens and the three, petal-like divisions of the style, each bearing a transverse stigma immediately above the anther. They are pollinated by bumble-bees, and in some instances by flies of the genus _Rhingia_, which search for the honey, brush the pollen out of the anthers and afterwards deposit it on the stigma. According to systematic views of the monocotyledons the original prototype of the genus _Iris_ must have had a whorl of six equal, or nearly equal perianth-segments and six stamens, such as are now seen in the more primitive types of the family of the lilies, as for instance in the lilies themselves, the tulips, hyacinths and others. As to the perianth this view is supported by the existence of one species, the _Iris falcifolia_, the perianth of which consists of six equal parts. But species with six stamens are wholly lacking. Heinricher however, in cultivating some anomalous forms of _Iris pallida_, succeeded in filling out this gap and in producing [174] flowers with a uniform perianth and six stamens, recalling thereby the supposed ancestral type. The way in which he got these was as follows: he started from some slight deviations observed in the flowers of the pale species, sowed the seeds in large numbers and selected from the seedlings only those which clearly showed anomalies in the expected atavistic direction. By repeating this during several generations he at last reached his goal and was able to give reality to the prototype, which formerly was only a hypothetical one. The _Iris kaempferi_, a large-flowered Japanese species much cultivated in gardens, is very variable in the number of the different parts of its flowers, and may in some instances be seen even with six stamens. If studied in the same way as Heinricher's iris, it no doubt will yield highly interesting and confirmatory results. Many other instances of such systematic atavism could be given, and every botanist can easily add some from memory. Many anomalies, occurring spontaneously, are evidently due to the same principle, but it would take too long to describe them. Reversion may occur either by buds or by seeds. It is highly probable that it occurs more readily by sexual than by asexual propagation. But if we restrict the discussion to the limits [175] hitherto observed, seed-reversions must be said to be extremely rare. Or rather cases which are sufficiently certain to be relied upon, are very rare, and perhaps wholly lacking. Most of the instances, recorded by various writers, are open to question. Doubts exist as to the purity of the seeds and the possibility of some unobserved cross disturbing the results. In the next lecture we shall deal in general with the ordinary causes and results of such crosses. We shall then see that they are so common and occur so regularly under ordinary circumstances that we can never rely on the absolute purity of any seeds, if the impossibility of an occasional cross has not been wholly excluded, either by the circumstances themselves, or by experimental precautions taken during the flowering period. For these reasons cases of atavism given without recording the circumstances, or the precautions that guarantee the purity of the fertilization, should always be disregarded. And moreover another proof should always be demanded. The parent which yielded the seeds might be itself a hybrid and liable to reversions by the ordinary laws of the splitting up of hybrids. Such cases should likewise be discarded, since they bring in confusing elements. If we review the long list of recorded cases by these [176] strict methods of criticism very few instances will be found that satisfy legitimate demands. On this ground it is by far safer in the present state of our knowledge, to accept bud-variations only as direct proofs of true atavism. And even these may not always be relied on, as some hybrids are liable to split up in a vegetative way, and in doing so to give rise to bud-variations that are in many respects apparently similar to cases of atavism. But fortunately such instances are as yet very rare. After this discussion it would be bold indeed to give instances of seed-atavism, and I believe that it will be better to refrain wholly from doing so. Many instances of so-called atavism are of purely morphologic nature. The most interesting cases are those furnished by the forms which some plants bear only while young, and which evidently connect them with allied species, in which the same features may be seen in the adult state. Some species of the genus _Acacia_ bear bipinnate leaves, while others have no leaves at all, but bear broadened and flattened petioles instead. The second type is presumed to be descended from the first by the loss of the leaflets and the modification of the stalks into flat and simple phyllodes. But many of them are liable to recall this primitive form [177] when very young, in the first two or three, or sometimes in eight or ten primary leaves. These leaves are small because of the weakness of the young plant and therefore often more or less reduced in structure. But they are usually strictly bipinnate and thereby give testimony as to their descent from species which bear such leaves throughout their life. Other similar cases could be given, but this will suffice. They once more show how necessary it is to separate the different cases, thrown together until now, under this general name of atavism. It would be far better to give them all special names, and as long as these are not available we must be cautious not to be misguided by the name, and especially not to confuse different phenomena with one another, because at the present time they bear the same names. Taking into consideration the relatively numerous restrictions resulting from this discussion, we will now make a hasty survey of some of the more notable and generally acknowledged cases of atavism by bud-propagation. But it should be repeated once more that most of the highly cultivated plants, grown as vegetables, or for their fruit or flowers, have so many crosses in their ancestry, that it seems better to exclude them from all considerations, in which purity of [178] descent is a requisite. By so doing, we exclude most of the facts which were until now generally relied upon. For the roses, the hyacinths, the tulips, the chrysanthemums always have furnished the largest contributions to the demonstrations of bud-variation. But they have been crossed so often, that doubt as to the purity of the descent of any single form may recur, and may destroy the usefulness of their many recorded cases of bud-variation for the demonstration of real atavism. The same assertion holds good in many other cases, as with _Azalea_ and _Camellia_. And the striped varieties of these genera belong to the group of ever-sporting forms, and therefore will be considered later on. So it is with carnations and pinks, which occasionally vary by layering, and of which some kinds are so uncertain in character that they are called by floriculturists "catch-flowers." On the other hand there is a larger group of cases of reversion by buds, which is probably not of hybrid nature, nor due to innate inconstancy of the variety, but must be considered as pure atavism. I refer to the bud-variations of so many of our cultivated varieties of shrubs and trees. Many of them are cultivated because of their foliage. They are propagated by grafting, and in most cases it is probable that all the numerous specimens [179] of the same variety have been derived in this way from one primitive, aberrant individual. We may disregard variegated leaves, spotted or marked with white or yellow, because they are too inconstant types. We may next turn our attention to the varieties of trees with cut leaves, as the oakleaved _Laburnum_, the parsley-leaved vine and the fern-leaved birch. Here the margin of the leaves is deeply cut and divided by many incisions, which sometimes change only the outer parts of the blade, but in other cases may go farther and reach, or nearly reach, the midvein, and change the simple leaf into a seemingly compound structure. The anomaly may even lead to the almost complete loss of all the chorophyll-tissue and the greater part of the lateral veins, as in the case of the cut-leaved beech or _Fagus sylvatica pectinata_. Such varieties are often apt to revert by buds to the common forms. The cut-leaved beech sometimes reverts partially only, and the branches often display the different forms of cut-leaved, fern-like, oak-leaved and other variously shaped leaves on the same twigs. But this is merely due to the wide variability of the degree of fissure and is to be considered only as a fluctuation between somewhat widely distant extremes, which may even apparently include [180] the form of the common beech-leaves. It is not a bud-variation at all, and it is to be met with quite commonly while the true reversions by buds are very rare and are of the nature of sports appearing suddenly and remaining constant on the same twig. Analogous phenomena of wide variability with true reversion may be seen in the variety of the European hornbeam called _Carpinus Betulus heterophylla_. The leaves of this tree generally show the greatest diversity in form. Some other cases have been brought together by Darwin. In the first place a subvariety of the weeping-willow with leaves rolled up into a spiral coil. A tree of this kind kept true for twenty-five years and then threw out a single upright shoot bearing flat leaves. The barberry (_Berberis_) offers another case; it has a well known variety with seedless fruit, which can be propagated by cuttings or layers, but its runners are said always to revert to the common form, and to produce ordinary berries with seeds. Most of the cases referred to by Darwin, however, seem to be doubtful and cannot be considered as true proofs of atavism until more is known about the circumstances under which they were produced. Red or brown-leaved varieties of trees and shrubs also occasionally produce green-leaved branches, and in this way revert to the type [181] from which they must evidently have arisen. Instances are on record of the hazel, _Corylus Avellana_, of the allied _Corylus tubulosa_, of the red beech, the brown birch and of some other purple varieties. Even the red bananas, which bear fruits without seeds and therefore have no other way of being propagated than by buds, have produced a green variety with yellow fruits. The _Hortensia_ of our gardens is another instance of a sterile form which has been observed to throw out a branch with cymes bearing in their center the usual small staminate and pistillate flowers instead of the large radiate and neutral corollas of the variety, thereby returning to the original wild type. Crisped weeping-willows, crisped parsley and others have reverted in a similar manner. All such cases are badly in need of a closer investigation. And as they occur only occasionally, or as it is commonly stated, by accident, the student of nature should be prepared to examine carefully any case which might present itself to him. Many phases of this difficult problem could no doubt be solved in this way. First of all the question arises as to whether the case is one of real atavism, or is only seemingly so, being due to hybrid or otherwise impure descent of the varying individual, and secondly whether it may be only an instance of the regularly [182] occurring so-called atavism of the sporting varieties with which we shall deal in a later lecture. If it proves to be real atavism and rare, the case should be accurately described and figured, or photographed if possible; and the exact position of the reverting bud should be ascertained. Very likely the so-called dormant or resting buds are more liable to reversions than the primary ones in the arils of the leaves of young twigs. Then the characters of the atavistic branches should be minutely compared with those of the presumed ancestor; they may be quite identical with them or slightly divergent, as has been asserted in some instances. The atavism may be complete in one case, but more or less incomplete in others. By far the most interesting point is the question, as to what is to be expected from the seeds of such an atavistic branch. Will they keep true to the reverted character, or return to the characters of the plant which bears the retrograde branch? Will all of them do so, or only part of them, and how large a part? It is very astonishing that this question should still be unsolved where so many individual trees bear atavistic branches that remain on them through long series of years. But then many such branches do not flower at all, or if they flower and bear seed, no care is taken to prevent [183] cross-fertilization with the other flowers of the same plant, and the results have no scientific value. For anyone who cares to work with the precautions prescribed by science, a wide field is here open for investigation, because old reverted branches may be met with much less rarely than new ones. Finally the possibility is always to be considered that the tendency to bud-reversions may be a special feature of some individuals, and may not be met with in others of the same variety. I have spoken of this before. For the practical student it indicates that a specimen, once observed to produce atavistic buds, may be expected to do the same thing again. And then there is a very good chance that by combining this view with the idea that dormant buds are more apt to revert than young ones, we may get at a method for further investigation, if we recur to the practice of pruning. By cutting away the young twigs in the vicinity of dormant buds, we may incite these to action. Evidently we are not to expect that in so doing they will all become atavistic. For this result is not at all assured; on the contrary, all that we might hope to attain would be the possibility of some of them being induced to sport in the desired direction. Many questions in scientific research can only [184] be answered by long and arduous work in well equipped laboratories; they are not to be attempted by every one. But there are other problems which the most complete of institutions are not able to study if opportunity is not offered them, and such opportunities are apt to occur more often in fields, gardens, parks, woods and plains, than in the relatively small experimental gardens of even the largest institution. Therefore, whosoever has the good fortune to find such sports, should never allow the occasion to pass without making an investigation that may bring results of very great importance to science. [185] LECTURE VII FALSE ATAVISM OR VICINISM About the middle of the last century Louis de Vilmorin showed that it was possible to subject plants to the methods of amelioration of races then in use for domestic animals, and since that time atavism has played a large part in all breeding-processes. It was considered to be the greatest enemy of the breeder, and was generally spoken of as a definite force, working against and protracting the endeavors of the horticulturist. No clear conception as to its true nature had been formulated, and even the propriety of designating the observed phenomena by the term atavism seemed doubtful. Duchesne used this word some decades ago to designate those cases in which species or varieties revert spontaneously, or from unknown internal causes, to some long-lost characters of their ancestors. Duchesne's definition was evidently a sharp and useful one, since it developed for the first time the idea of latent or dormant qualities, [186] formerly active, and awaiting probably through centuries an occasion to awaken, and to display the lost characters. Cases of apparent reversion were often seen in nurseries, especially in flower culture, which under ordinary circumstances are rarely wholly pure, but always sport more or less into the colors and forms of allied varieties. Such sporting individuals have to be extirpated regularly, otherwise the whole variety would soon lose its type and its uniformity and run over to some other form in cultivation in the vicinity. For this reason atavism in nurseries causes much care and labor, and consequently is to be dealt with as a very important factor. From time to time the idea has suggested itself to some of the best authorities on the amelioration of plants, that this atavism was not due to an innate tendency, but, in many cases at least, was produced by crosses between neighboring varieties. It is especially owing to Verlot that this side of the question was brought forward. But breeders as a rule have not attached much importance to this supposition, chiefly because of the great practical difficulties attending any attempt to guard the species of the larger cultures against intermixture with other varieties. Bees and humble-bees fly from bud to bud, and carry the pollen from one [187 ] sort to another, and separation by great distances would be required to avoid this source of impurity. Unfortunately the arrangements and necessities of large cultures make it impossible to isolate the allied varieties from each other. From a theoretical point of view the origin of these impurities is a highly important question. If the breeders' atavism is due to crosses, and only to this cause, it has no bearing at all on the question of the constancy of varieties. And the general belief, that varieties are distinguished from true species by their repeated reversion and that even such reversibility is the real distinction of a variety, would not hold. For this reason I have taken much trouble in ascertaining the circumstances which attend this form of atavism. I have visited a number of the leading nurseries of Europe, tested their products in various ways, and made some experiments on the unavoidable conditions of hybridizing and on their effect on the ensuing generations. These investigations have led me to the conclusion, that atavism, as it is generally described, always or nearly always is due to hybridization, and therefore it is to be considered as untrue or false atavism. True atavism, or reversion caused by an innate latent tendency, seems to be very rare, [188] and limited to such cases as we have spoken of under our last heading. And since the definition, given to this term by its author, Duchesne, is generally accepted in scientific works, it seems better not to use it in another sense, but rather to replace it in such cases by another term. For this purpose I propose the word vicinism, derived from the Latin vicinus or neighbor, as indicating the sporting of a variety under the influence of others in its vicinity. Used in this way, this term has the same bearing as the word atavism of the breeders, but it has the advantage of indicating the true cause thereof. It is well known that the term variability is commonly employed in the broadest possible sense. No single phenomenon can be designated by this name, unless some primary restriction be given. Atavism and vicinism are both cases of variability, but in wholly different sense. For this reason it may be as well, to insert here a short survey of the general meanings to be conveyed by the term variation. It implies in the first place the occurrence of a wide range of forms and types, irrespective of their origin, and in the second place the process of the change in such forms. In the first signification it is nearly identical with polymorphy, or richness of types, especially so when these [189] types are themselves quite stable, or when it is not at all intended to raise the question of their stability. In scientific works it is commonly used to designate the occurrence of subspecies or varieties, and the same is the case in the ordinary use of the term when dealing with cultivated plants. A species may consist of larger or smaller groups of such units, and they may be absolutely constant, never sporting if hybridization is precluded, and nevertheless it may be called highly variable. The opium-poppy affords a good instance. It "varies" in height, in color of foliage and flowers; the last are often double or laciniated; it may have white or bluish seeds, the capsules may open themselves or remain closed and so on. But every single variety is absolutely constant, and never runs into another, when the flowers are artificially pollinated and the visits of insects excluded. So it is with many other species. They are at the same time wholly stable and very variable. The terms variation and variety are used frequently when speaking of hybrids. By crossing forms, which are already variable in the sense just mentioned, it is easy to multiply the number of the types, and even in crossing pure forms the different characters may be combined in different ways, the resulting combinations [190] yielding new, and very often, valuable varieties. But it is manifest that this form of variation is of quite another nature from the variations of pure races. Many hybrid varieties are quite constant, and remain true to their type if no further crosses are made; many others are artificially propagated only in a vegetative way, and for this reason are always found true. Hybrid varieties as a rule were formerly confused with pure varieties, and in many instances our knowledge as to their origin is quite insufficient for sharp distinctions. To every student of nature it is obvious, that crossing and pure variability are wholly distinct groups of phenomena, which should never be treated under the same head, or under the same name. Leaving aside polymorphy, we may now discuss those cases of variability, in which the changes themselves, and not only their final results play a part. Of such changes two types exist. First, the ever-recurring variability, never absent in any large group of individuals, and determining the differences which are always to be seen between parents and their children, or between the children themselves. This type is commonly called "individual variability" and since this term also has still other meanings, it has of late become customary to use instead the term "fluctuating variability." [191] And to avoid the repetition of the latter word it is called "fluctuation." In contrast to these fluctuations are the so-called sports or single varieties, not rarely denominated spontaneous variations, and for which I propose to use the term "mutations." They are of very rare occurrence and are to be considered as sudden and definite steps. Lastly, we have to consider those varieties, which vary in a much wider range than the ordinary ones, and seem to fluctuate between two opposite extremes, as for instance variegated leaves, cultivated varieties with variegated or striped flowers, double flowers and some other anomalies. They are eversporting and ever-returning from one type to the other. If however, we take the group of these extremes and their intermediates as a whole, this group remains constant during the succeeding generations. Here we find once more an instance of the seemingly contradictory combination of high variability and absolute constancy. It means that the range of variability has quite definite limits, which in the common course of things, are never transgressed. We may infer therefore that the word variability has such a wide range of meanings that it ought never be used without explanation. [192] Nothing indeed, is more variable than the signification of the term variable itself. For this reason, we will furthermore designate all variations under the influence of neighbors with the new and special term "vicinism." It always indicates the result of crossing. Leaving this somewhat lengthy terminological discussion, we now come to the description of the phenomenon itself. In visiting the plantations of the seedsmen in summer and examining the large fields of garden-flowers from which seed is to be gathered, it is very rare to find a plot quite pure. On the contrary, occasional impurities are the rule. Every plot shows anomalous individuals, red or white flowers among a field of blue, normal among laciniated, single among double and so on. The most curious instance is afforded by dwarf varieties, where in the midst of hundreds and thousands of small individuals of the same height, some specimens show twice their size. So for instance, among the dwarfs of the larkspur, _Delphinium Ajacis_. Everywhere gardeners are occupied in destroying these "atavists," as they call them. When in full bloom the plants are pulled up and thrown aside. Sometimes the degree of impurity is so high, that great piles of discarded plants of the same species lie about the [193] paths, as I have seen at Erfurt in the ease of numerous varieties of the Indian cress or _Tropaeolum_. Each variety is purified at the time when it shows its characters most clearly. With vegetables, this is done long before flowering, but with flowers only when in full bloom, and with fruits, usually after fertilization has been accomplished. It needs no demonstration to show that this difference in method must result in very diverging degrees of purity. We will confine ourselves to a consideration of the flowers, and ask what degree of purity may be expected as the result of the elimination of the anomalous plants during the period of blooming. Now it is evident that the colors and forms of the flowers can only be clearly distinguished, when they are fully displayed. Furthermore it is impossible to destroy every single aberrant specimen as soon as it is seen. On the contrary, the gardener must wait until all or nearly all the individuals of the same variety have displayed their characters, as only in this way can all diverging specimens be eliminated by a single inspection. Unfortunately the insects do not wait for this selection. They fertilize the flowers from the beginning, and the damage will have been done [194] long before the day of inspection comes around. Crosses are unavoidable and hybrid seeds will unavoidably come into the harvest. Their number may be limited by an early eradication of the vicinists, or by the elimination of the first ripe seeds before the beginning of the regular harvest, or by other devices. But some degree of impurity will remain under ordinary circumstances. It seems quite superfluous to give more details. In any case in which the selection is not done before the blooming period, some impurities must result. Even if it is done before that time, errors may occur, and among hundreds and thousands of individuals a single anomalous one may escape observation. The conclusion is, that flower seeds as they are offered in commerce, are seldom found absolutely pure. Every gardener knows that he will have to weed out aberrant plants in order to be sure of the purity of his beds. I tested a large number of samples of seeds for purity, bought directly from the best seed growers. Most of them were found to contain admixtures and wholly pure samples were very rare. I will now give some illustrative examples. From seeds of a yellow snapdragon, I got one red-flowered specimen among half a hundred [195] yellow ones, and from the variety "Delila" of the same species two red ones, a single white and two belonging to another variety called "Firefly." _Calliopsis tinctoria_ has three varieties, the ordinary type, a brown-flowered one and one with tubular rays. Seeds of each of these three sorts ordinarily contain a few belonging to the others. _Iberis umbellata rosea_ often gives some white and violet examples. The "Swan" variety of the opium-poppy, a dwarfish double-flowered form of a pure white, contained some single-flowered and some red-flowered plants, when sown from commercial seed are said to be pure. But these were only occasional admixtures, since after artificial fertilization of the typical specimens the strain at once became absolutely pure, and remained so for a series of generations, as long as the experiment was continued. Seeds of trees often contain large quantities of impurities, and the laciniated varieties of birch, elder and walnut have often been observed to come true only in a small number of seedlings. In the case of new or young varieties, seed merchants often warn their customers as to the probable degree of purity of the seeds offered, in order to avoid complaints. For example the snow-white variety of the double daisy, _Bellis perennis plena_, was offered at the start as containing [196] as much as 20% of red-flowered specimens. Many fine varieties are recorded to come true from seed, as in the case of the holly with yellow fruits, tested by Darwin. Others have been found untrue to a relatively high degree, as is notorious in the case of the purple beech. Seeds of the laciniated beech gave only 10% of laciniated plants in experiments made by Strasburger; seeds of the monophyllous acacia, _Robinia Pseud-Acacia monophylla_, were found to be true in only 30% of the seedlings. Weeping ashes often revert to the upright type, red May-thorns (_Crataegus_) sometimes revert nearly entirely to the white species and the yellow cornel berry is recorded to have reverted in the same way to the red berries of the _Cornus Mas_. Varieties have to be freed by selection from all such impurities, since isolation is a means which is quite impracticable under ordinary circumstances. Isolation is a scientific requirement that should never be neglected in experiments, indeed it may be said to be the first and most important requisite for all exact research in questions of variability and inheritance. But in cultivating large fields of allied varieties for commercial purposes, it is impossible to grow them at such distances from each other [197] as to prevent cross-pollination by the visits of bees. This purification must be done in nearly every generation. The oldest varieties are to be subjected to it as well as the latest. There is no regular amelioration, no slow progression in the direction of becoming free from these admixtures. Continuous selection is indispensable to maintain the races in the degree of purity which is required in commerce, but it does not lead to any improvement. Nor does it go so far as to become unnecessary in the future. This shows that there must be a continuous source of impurities, which in itself is not neutralized by selection, but of which selection can only eliminate the deteriorating elements. The same selection is usually applied to new varieties, when they occasionally arise. In this case it is called "fixing," as gardeners generally believe that through selection the varieties are brought to the required degree of purity. This belief seems to rest mainly on observations made in practice, where, as we have seen, isolation is of very rare application. Most varieties would no doubt be absolutely pure from the first moment of their existence, if it were only possible to have them purely fertilized. But in practice this is seldom to be obtained. Ordinarily the breeder is content with such slow [198] improvement as may be obtained with a minimum of cost, and this mostly implies a culture in the same part of the nursery with older varieties of the same species. Three, four or five years are required to purify the novelty, and as this same length of time is also required to produce sufficient quantities of seed for commercial purposes, there is no strong desire to shorten the period of selection and fixation. I had occasion to see this process going on with sundry novelties at Erfurt in Germany. Among them a chamois-colored variety of the common stock, a bluish _Clarkia elegans_ and a curiously colored opium-poppy may be mentioned. In some cases the crossfertilization is so overwhelming, that in the next generation the novelty seems entirely to have disappeared. The examples given may suffice to convey a general idea of the phenomenon, ordinarily called atavism by gardeners, and considered mostly to be the effect of some innate tendency to revert to the ancestral form. It is on this conception that the almost universal belief rests, that varieties are distinguished, as such, from species by their inconstancy. Now I do not deny the phenomenon itself. The impurity of seeds and cultures is so general and so manifest, and may so easily be tested by every one [199] that it cannot reasonably be subjected to any doubt. It must be conceded to be a fact, that varieties as a rule revert to their species under the ordinary circumstances of commercial culture. And I cannot see any reason why this fact should not be considered as stating a principal difference between varieties and species, since true species never sport into one another. My objection only refers to the explanation of the observed facts. According to my view nearly all these ordinary reversions are due to crosses, and it is for this reason that I proposed to call them by a separate name, that of "vicinists." Varieties then, by means of such spontaneous intercrossing sport into one another, while species either do not cross, or when crossing produce hybrids that are otherwise constituted and do not give the impression of atavistic reversion. I must not be content with proposing this new conception, but must give the facts on which this assumption rests. These facts are the results of simple experiments, which nevertheless are by no means easy to carry out, as they require the utmost care to secure the absolute purity of the seeds that are employed. This can only be guaranteed by previous cultures of isolated plants or groups of plants, or by artificial pollination. [200] Once sure of this preliminary condition, the experiment simply consists in growing a variety at a given distance from its species and allowing the insects to transfer the pollen. After harvesting the seed thus subjected to the presumed cause of the impurities, it must be sown in quantities, large enough to bring to light any slight anomaly, and to be examined during the period of blooming. The wild seashore aster, _Aster Tripolium_, will serve as an example. It has pale violet or bluish rays, but has given rise to a white variety, which on testing, I have found pure from seed. Four specimens of this white variety were cultivated at a distance of nearly 100 meters from a large lot of plants of the bluish species. I left fertilization to the bees, harvested the seeds of the four whites separately and had from them the following year more than a thousand flowering plants. All of them were of the purest white, with only one exception, which was a plant with the bluish rays of the species, wholly reverting to its general type. As the variety does not give such reversions when cultivated in isolation, this sport was obviously due to some cross in the former year. In the same way I tried the white Jacob's ladder, _Polemonium coeruleum_ album in the neighborhood of the blue-flowered species, the distance [202] in this case being only 40 meters. Of two hundred seeds one became a blue atavist, or rather vicinist, while all others remained true to the white type. The same was observed in the white creeping thyme, or _Thymus Serpyllum album_, and the white self-heal, _Brunella vulgaris alba_, gave even so much as 28% seedlings with purple corollas out of some 400 specimens, after being cultivated in close proximity to its parent-species. I have tried many other species, but always with the same result. Such atavists only arise by cultivation in the proximity of allied varieties, never in isolation. They are not real atavists, but only vicinists. In order to show this yet more clearly, I made another experiment with the white selfheal. I had a lot of the pinnate-leaved variety with purple flowers and somewhat stouter stems, and cultivated single plants of the whiteflowering sort at distances that varied from 2-16 meters. The seeds of each plant were collected and sown separately, those of the nearest gave up to 5 or 6 hybrids from the seeds of one parent, while those of the farthest gave only one purple-flowered plant for each parent. Evidently the chance of the pollen being carried by bees is much greater on short than on longer distances. True hybrids between species may arise in quite the same way, and since it is obviously impossible to attribute them to an innate tendency to reversion, they afford an absolutely irrefutable proof of the assertion that pollen is often brought by insects from one lot of plants to another. In this way I obtained a hybrid between the common Jacob's ladder and the allied species _Polemonium dissectum_. With a distance of 100 meters between them I had two hybrid seeds among a hundred of pure ones. At a similar distance pollen was carried over from the wild radish, _Raphanus Raphanistrum_, to the allied _Raphanus caudatus_, and I observed the following year some very nice hybrids among my seedlings. A hybrid-bean between _Phaseolus nanus_ and _P. multiflorus_, and some hybrids between the yellow daisy, _Chrysanthemum segetum_ and the allied _Chrysanthemum coronarium_ or ox-eye daisy which also arose spontaneously in my garden between parents cultivated at recorded distances, might further be noted. Further details of these experiments need not be given. Suffice to say, that occasional crosses between species do occur, and not even rarely, that they are easily recognized as such and cannot be confused with cases of atavism, and that therefore they give proof to the assumption that in the same way crosses ordinarily occur also between varieties [203] of the same species, if cultivated at small distances apart, say 40-50 meters or even more. Vicinism therefore, may play a part in all such cultures, enough to account for all the impurities observed in the nurseries or in commercial seed-samples. Of course this whole discussion is limited to such species as are not only as a rule visited by insects, but are dependent on these visits for their fertilization. Most of our garden-flowers are included in this category. If not then we may expect to find the cultures and seeds pure, irrespective of the distances between allied varieties, as for instance with peas, which are known to be self-fertilizing. Another instance is given by the barley. One of the most curious anomalous varieties of this cereal, is the "Nepaul-barley," with its small adventitious flowers on the palets or inner scales. It is a very old, widely cultivated sort, which always comes true from seed, and which has been tested in repeated experiments in my garden. The spikelets of this curious plant are oneflowered and provided with two linear glumes or outer scales. Of the inner scales or palets, the outer one is three-lobed at the summit, hence the varietal name of _Hordeum vulgare trifurcatum_. The central lobe is oblong and hollow, covering a small supernumerary floret inserted [204] at its base. The two lateral lobes are narrower, sometimes linear, and are often prolonged into an awn, which is generally turned away from the center of the spike. The central lobe sometimes bears two florets at its base, although but one is usually present and it may be incomplete. I might give one more instance from my own experience. A variety of the evening-primrose with small linear petals was once found by one of my sons growing wild near Amsterdam. It was represented by only one individual, flowering among a great many of the ordinary type with broad petals. But the evening-primroses open their anthers in the morning, fertilize themselves during the day, and only display their beautiful flowers in the evening, after the pollination has been accomplished. They then allure evening moths, such as _Agrotis_ and _Plusia_, by their bright color, their sweet honeysmell and their nectar. Since the fertilization is accomplished many hours before opening, crosses are effected only in rare instances, and the seeds commonly remain true to the parent type. The seeds of this one plant, when sown separately in my garden, produced exclusively flowers with the small linear petals of their parent. Although I had a hundred individuals bearing many thousands of flowers, there was not an instance of reversion. And such would [205] immediately have been observed, had it occurred, because the hybrids between the cruciate and the normal flowers are not intermediate, but bear the broad petals of the _O. biennis_. We may now take up another phase of the question, that of the running out of new varieties, shortly after their introduction into a new country, or later. The most widely known instance of this is that of the American corn in Baden, recorded by Metzger and quoted by Darwin as a remarkable instance of the direct and prompt action of climate on a plant. It has since been considered as a reversion to the old type. Such reversions invariably occur, according to Wallace, in cases of new varieties, which have been produced quickly. But as we now know, such reversions are due to spontaneous crosses with the old form, and to the rule, that the hybrids of such origin are not intermediate, but assume the features of the older of the two parents. In the light of this experience, Metzger's observation becomes a typical instance of vicinism. It relates to the "Tuscarora" corn of St. Louis, a variety with broad and flat white seeds. About the year 1840, this corn was introduced into Baden in Germany, and cultivated by Metzger. In the first year it came true to type, and [206] attained a height of 12 feet, but the season did not allow its seeds to ripen normally. Only a few kernels were developed before the winter. From this seed plants of a wholly different type came the next year, of smaller stature, and with more brownish and rounded kernels. They also flowered earlier and ripened a large number of seeds. The depression on the outer side of the seed had almost disappeared, and the original white had become darker. Some of the seeds had even become yellow and in their rounded form they approached the common European maize. Obviously they were hybrids, assuming the character of their pollen-parent, which evidently was the ordinary corn, cultivated all around. The observation of the next year showed this clearly, for in the third generation nearly all resemblance to the original and very distinct American species was lost. If we assume that only those seeds ripened which reverted to the early-ripening European type, and that those that remained true to the very late American variety could not reach maturity, the case seems to be wholly comprehensible, without supposing any other factors to have been at work than those of vicinism, which though unknown at the period of Metzger's and Darwin's writings, seems now to be fully understood. No innate tendency to run out and no changing influence of the climate are required for an adequate explanation of the facts. In the observation quoted, what astonishes us most, is the great rapidity of the change, and the short time necessary for the offspring of the accidental crosses to completely supplant the introduced type. In the lecture on the selection of elementary species, closely analogous cases were described. One of them was the wild oat or _Avena fatua_ which rapidly supplants the cultivated oats in bad years in parts of the fields. Other instances were the experiments of Risler with the "Galland" wheat and the observation of Rimpau on "Rivett's bearded" wheat. Before leaving the question of vicinism and its bearing on the general belief of the instability of varieties, which when tested with due care, prove to be quite stable, it may be as well to consider the phenomena from another point of view. Our present knowledge of the effects of crosses between varieties enables us to formulate some general rules, which may be used to calculate, and in some way to predict, the nature of the impurities which necessarily attend the cultivation of allied species in close vicinity. And this mode of cultivation being in almost universal use in the larger nurseries, [208] we may, by this discussion, arrive at a more scientific estimation of the phenomena of vicinism, hitherto described. The simplest case that may be given, is when an ordinary retrograde variety is cultivated with the species to which it belongs. For instance, if dwarfs are cultivated next to the taller type, or a white variety next to the red or blue-flowering species, or thornless forms in neighboring beds with the armed species. Bees and Bumble-bees, butterflies and moths are seen flying from flower to flower, collecting the honey and carrying pollen. I frequently saw them cross the limits of the neighboring beds. Loaded with the pollen of the variety they visit the flowers of the different species and impregnate the stigma with it. And returning to the variety they bring about similar crosses in the flowers of the latter. Hybrid seeds will develop in both cases and become mixed with the crop. We now have to ask the question, what sort of plants will arise from these hybrid seeds. As a general rule we may state, first, that the hybrids of either form of cross are practically the same, secondly that they are not intermediate, but that the character of one parent prevails to the almost absolute exclusion of the other and in the third place that the older character dominates the younger. [209] The hybrid offspring will therefore, in the main, have the character of the species and be indistinguishable from it, or show only such differences as escape ordinary observation. When occurring in the seeds of the variety they betray themselves as soon as the differential characters are displayed. Between the thousands of flowering plants of a white variety the hybrids will instantly catch the eye by their red or blue corollas. Quite the contrary effect results from the admixture of hybrids with the seeds of the species itself. Here no difference will show itself, even in the fullest bloom. The effect of the spontaneous crosses will pass unobserved. The strain, if pure in the first year, will seem to be still in the same condition. Or in other terms, the unavoidable spontaneous crosses will disturb the purity of the variety in the second year, while they do not seem to interfere at all with the uniformity of the species. The direct effect of the visits of the insects is evident in the first case, but passes unobserved in the latter. From this it would seem, that spontaneous crosses are hurtful to varieties, but are innocuous to true species. Certainly this would be so, were there no selection. But it is easily seen, that through this operation the effect becomes quite the opposite. For when the fields [210] are inspected at the time of the fullest display of the varietal characters, the obvious hybrids will be eliminated, but the hidden ones will of necessity be spared, as they are concealed among the species by the similarity of their type. Hence, the harvest of the variety may be rendered pure or nearly so, while the harvest of the species will retain the seeds of the hybrids. Moreover it will contain seeds originated by the spontaneous but numerous crosses of the true plants with the sparsely intermingled hybrids. This brings us to the question, as to what will be the visible consequences of the occurrence of such invisible hybrids in the following generation. In opposition to the direct effects just described, we may call them indirect. To judge of their influence, we must know how hybrid seeds of the first generation behave. In one of our lectures we will deal with the laws that show the numerical relations known as the laws of Mendel. But for our present purpose, these numerical relations are only of subordinate importance. What interests us here is the fact that hybrids of varieties do not remain constant in the second generation but usually split as it is said, remaining hybrid only in part of their offspring, the other portion returning to the parental types. This however, will show itself only in those individuals [211] which reassume the character of the varietal parent, all the others apparently remaining true to the type of the species. Now it is easy to foresee what must happen in the second generation if the first generation after the cross is supposed to be kept free from new vicinistic influences, or from crosses with neighboring varieties. We may limit ourselves in the first place to the seeds of the unobserved hybrids. For the greater part they will repeat the character of their parents and still remain concealed. But a small number will display the varietal marks, as for example showing white flowers in a field of blue ones. Hence, the indirect consequence of the spontaneous crosses will be the same in the species, as was the direct effect in the variety, only that it appears a year later. It will then be eliminated in the process of selection. Obviously, this elimination conduces only to a partial purification. The conspicuous plants will be destroyed, but a greater number of hybrids will remain, still concealed by their resemblance to the general type and will be spared to repeat the same process next year. So while the variety may be freed every year from the impurities brought into it in the preceeding summer, the admixtures of the species [212] will continue during a number of years, and it may not be possible to get rid of them at all. It is an often recurring assertion that white varieties of colored species are the most stable of all horticultural races. They are often said to be at least as constant as the species itself, and even to surpass it in this quality. With our present state of knowledge, the explanation of this general experience is easily given. For selection removes the effect of spontaneous crosses from the variety in each year, and renders it practically pure, while it is wholly inadequate to produce the same effects on the species, because of the concealed hybrids. The explanation given in this simple instance may be applied to the case of different varieties of the same species, when growing together and crossed naturally by insects. It would take too long to go into all the details that present themselves here to the student of nature and of gardens. I will only state, that since varieties differ principally from their species by the lack of some sharp character, one variety may be characterized by the lack of color of the flowers, another by the lack of pubescence, a third by being dwarfed, and so on. Every character must be studied separately in its effects on the offspring [213] of the crosses. And it is therefore easily seen, that the hybrids of two varieties may resemble neither of them, but revert to the species itself. This is necessarily and commonly the case, since it is always the older or positive characters that prevail in the hybrids and the younger or negative that lie hidden. So for instance, a blue dwarf larkspur, crossed with a tall white variety, must give a tall blue hybrid, reassuming in both characters the essentials of the species. Keeping this rule in view, it will be easy to calculate what may be expected from spontaneous crosses for a wide range of occurrences, and thus to find an explanation of innumerable cases of apparent variability and reversion in the principle of vicinism. Students have only to recollect that specific characters prevail over varietal ones, and that every character competes only with its own antagonist. Or to give a sharper distinction: whiteness of flowers cannot be expected to be interchanged with pubescence of leaves. In concluding I will point out another danger which in the principle of vicinism may be avoided. If you see a plant in a garden with all the characteristics of its species, how can you be sure that it is truly a representative of the species, and not a hybrid? The prevailing [214] characters are in either case the same. Perhaps on close inspection you may find in some cases a slight difference, some character being not as fully developed in the hybrid as in the species. But when such is not the case, or where the opportunity for such a closer examination is wanting, a hybrid may easily be taken for a specimen of the pure race. Now take the seeds of your plant and sow them. If you had not supposed it to be hybrid you will be astonished at finding among its progeny some of a wholly different type. You will be led to conclude that you are observing a sudden change in structure such as is usually called a sport. Or in other words you may think that you are assisting at the origination of a new variety. If you are familiar with the principle of vicinism, you will refrain from such an inference and consider the supposition of a hybrid origin. But in former times, when this principle was still unknown and not even guessed at, it is evident that many mistakes must have been made, and that many an instance, which until now has been considered reliable proof of a so-called single variation, is in fact only a case of vicinism. In reading the sparse literature on sports, numerous cases will be found, which cannot stand this test. In many instances crossing must be looked to as an explanation, [215] and in other cases the evidence relied upon does not suffice to exclude this assumption. Many an old argument has of late lost its force by this test. Returning to our starting point we may now state that regular reversions to a specific type characterize a form as a variety of that species. These reversions, however, are not due to an innate tendency, but to unobserved spontaneous crosses. [217] LECTURE VIII LATENT CHARACTERS No organism exhibits all of its qualities at any one time. Many of them are generally dormant and await a period of activity. For some of them this period comes regularly, while in others the awakening depends upon external influences, and consequently occurs very irregularly. Those of the first group correspond to the differences in age; the second constitute the responses of the plant to stimuli including wound-injuries. Some illustrative examples may be quoted in order to give a precise idea of this general conception of dormant or latent characters. Seed leaves are only developed in the seed and the seedling; afterwards, during the entire lifetime of the plant, the faculty of producing them is not made use of. Every new generation of seeds however, bears the same kind of seed leaves, and hence it is manifest that it is the same quality, which shows itself from time to time. The primary leaves, following the seed-leaves, are different in many species, from the later ones, and the difference is extremely pronounced in some cases of reduction. Often, when leaves are lacking in the adult plant, being replaced by flattened stalks as in the case of the acacias, or by thorns, or green stems and twigs as in the prickly broom or _Ulex europaeus_, the first leaves of the young plant may be more highly differentiated, being pinnate in the first case and bearing three leaflets in the second instance. This curious behavior which is very common, brings the plants, when young, nearer to their allies than in the adult state, and manifestly implies that the more perfect state of the leaves is latent throughout the life of the plant, with the exception of the early juvenile period. _Eucalyptus Globulus_, the Australian gum tree, has opposite and broadly sessile leaves during the first years of its life. Later these disappear and are replaced by long sickle-shaped foliage organs, which seem to be scattered irregularly along the branches. The juvenile characters manifestly lie dormant during the adult period, and that this is so, may be shown artificially by cutting off the whole crown of the tree, when the stem responds by producing numerous new branches, which assume the [218] shape proper to the young trees, bearing sessile and opposite leaves. It seems quite unnecessary to give further instances. They are familiar to every student. It is almost safe to say that every character has its periods of activity and of inactivity, and numbers of flowers and fruits can be mentioned as illustrations. One fact may be added to show that nearly every part of the plant must have the power of producing all or nearly all the characters of the individual to which it belongs. This proof is given by the formation of adventitious buds. These, when once formed, may grow out into twigs, with leaves and flowers and roots. They may even be separated from the plants and used as cuttings to reproduce the whole. Hence we may conclude that all tissues, which possess the power of producing adventitious buds, must conceal in a latent state, all the numerous characters required for the full development of the whole individual. Adventitious buds may proceed from specialized cells, as on the margin of the leaves of _Bryophyllum calycinum_; or from the cells of special tissues, as in the epidermis of the begonias; or they may be provoked by wounds in nearly every part of the plant, provided it be able to heal the wound by swelling tissues or [219] callus. The best instance is afforded by elms and by the horse-chestnut. If the whole tree is hewn down the trunk tries to repair the injury by producing small granulations of tissue between the wood and the bark, which gradually coalesce while becoming larger. From this new ring of living matter innumerable buds arise, that expand into leafy branches, showing clearly that the old trunk possesses, in a latent state, all the qualities of the whole crown. Indeed, such injured stumps may be used for the production of copses and hedges. All the hitherto recorded cases of latency have this in common, that they may become active during the life-time of any given individual once, or oftener. This may be called the ordinary type of latency. Besides this there is another form of latent characters, in which this awakening power is extremely limited, or wholly absent. It is the systematic latency, which may be said to belong to species and varieties in the same way as the ordinary latency belongs to individuals. As this individual latency may show itself from time to time during the life of a given plant, the first may only become active from time to time during the whole existence of the variety or the species. It has no regular period of activity, nor may it be incited by artificial stimulation. [220] It emerges from concealment only very rarely and only on its own initiative. Such instances of atavism have been described in previous lectures, and their existence has been proved beyond doubt. Systematic latency explains the innumerable instances in which species are seen to lack definite characteristics which ordinarily do not fail, either in plants at large, or in the group or family to which the plant belongs. If we take for instance the broom-rape or _Orobanche_, or some other pale parasite, we explain their occurrence in families of plants with green leaves, by the loss of the leaves and of the green color. But evidently this loss is not a true one, but only the latency of those characters. And even this latency is not a complete one, as little scales remind us of the leaves, and traces of chlorophyll still exist in the tissues. Numerous other cases will present themselves to every practical botanist. Taking for granted that characters, having once been acquired, may become latent, and that this process is of universal occurrence throughout the whole vegetable and animal kingdom, we may now come to a more precise and clear conception of the existing differences between species and varieties. For this purpose we must take a somewhat [221] broader view of the whole evolution of the vegetable kingdom. It is manifest that highly developed plants have a larger number of characters than the lower groups. These must have been acquired in some way, during preceding times. Such evolution must evidently be called a process of improvement, or a progressive evolution. Contrasted to this is the loss, or the latency of characters, and this may be designated retrogressive or retrograde evolution. But there is still a third possibility. For a latent character may reassume its activity, return to the active state, and become once more an important part of the whole organization. This process may be designated as degressive evolution; it obviously completes the series of the general types of evolution. Advancement in general in living nature depends on progressive evolution. In different parts of the vegetable kingdom, and even in different families this progression takes place on different lines. By this means it results in an ever increasing divergency between the several groups. Every step is an advance, and many a step must have been taken to produce flowering plants from the simplest unicellular algae. But related to, and very intimately connected with this advancement is the retrogressive [222] evolution. It is equally universal, perhaps never failing. No great changes have been attained, without acquiring new qualities on one side, and reducing others to latency. Everywhere such retrogressions may be seen. The polypetalous genera _Pyrola_, _Ledum_, and _Monotropa_ among the sympetalous heaths, are a remarkable instance of this. The whole evolution of the monocotyledons from the lowest orders of dicotyledons implies the seeming loss of cambial growth and many other qualities. In the order of aroids, from the calamus-root or sweet flag, with its small but complete flowers, up to the reduced duckweeds (_Lemna_), almost an unbroken line of intermediate steps may be traced showing everywhere the concurrence of progressive and retrogressive evolution. Degressive evolution is not so common by far, and is not so easy to recognize, but no doubt it occurs very frequently. It is generally called atavism, or better, systematic atavism, and the clearest cases are those in which a quality which is latent in the greater part of a family or group, becomes manifest in one of its members. Bracts in the inflorescence of crucifers are ordinarily wanting, but may be seen in some genera, _Erucastrum pollichii_ being perhaps the [223] most widely known instance, although other cases might easily be cited. For our special purpose we may take up only the more simple cases that may be available for experimental work. The great lines of evolution of whole families and even of genera and of many larger species obviously lie outside the limits of experimental observation. They are the outcome of the history of the ancestors of the present types, and a repetition of their history is far beyond human powers. We must limit ourselves to the most recent steps, to the consideration of the smallest differences. But it is obvious that these may be included under the same heads as the larger and older ones. For the larger movements are manifestly to be considered only as groups of smaller steps, going in the same direction. Hence we conclude, that even the smallest steps in the evolution of plants which we are able to observe, may be divided into progressive, retrogressive and degressive ones. The acquisition of a single new quality is the most simple step in the progressive line, the becoming latent and the reactivating of this same quality are the prototypes of the two other classes. Having taken this theoretical point of view, it remains to inquire, how it concurs with the [224] various facts, given in former lectures and how it may be of use in our further discussions. It is obvious that the differences between elementary species and varieties on the one hand, and between the positive and negative varieties as distinguished above, are quite comparable with our theoretical views. For we have seen that varieties can always be considered as having originated by an apparent loss of some quality of the species, or by the resumption of a quality which in allied species is present and visible. In our exposition of the facts we have of course limited ourselves to the observable features of the phenomena without searching for a further explanation. For a more competent inquiry however, and for an understanding of wider ranges of facts, it is necessary to penetrate deeper into the true nature of the implied causes. Therefore we must try to show that elementary species are distinguished from each other by the acquisition of new qualities, and that varieties are derived from their species either by the reduction of one or more characteristics to the latent state, or by the energizing of dormant characters. Here we meet with a great difficulty. Hitherto varieties and subspecies have never been clearly defined, or when they have been, it was [225] not by physiological, but only by morphological research. And the claims of these two great lines of inquiry are obviously very diverging. Morphological or comparative studies need a material standard, by which it may be readily decided whether certain groups of animals and plants are to be described or de-nominated as species, as subspecies or as varieties. To get at the inner nature of the differences is in most cases impossible, but a decision must be made. The physiological line of inquiry has more time at its disposal; it calls for no haste. Its experiments ordinarily cover years, and a conclusion is only to be reached after long and often weary trials. There is no making a decision on any matter until all doubtful points have been cleared up. Of course, large groups of facts remain uncertain, awaiting a closer inquiry, and the teacher is constrained to rely on the few known instances of thoroughly investigated cases. These alone are safe guides, and it seems far better to trust to them and to make use of them for the construction of sharp conceptions, which may help us to point out the lines of inquiry which are still open. Leaving aside all such divisions and definitions, as were stamped with the name of provisional species and varieties by the great systematist, [226] Alphonse De Candolle, we may now try to give the proofs of our assertion, by using only those instances that have been thoroughly tested in every way. We may at once proceed to the retrogressive or negative varieties. The arguments for the assumption that elementary species owe their origin to the acquisition of new qualities may well be left for later lectures when we shall deal with the experimental proofs in this matter. There are three larger groups of facts, on which the assumption of latent characters in ordinary varieties rests. These are true atavism, incomplete loss of characters, and systematic affinity. Before dealing with each of these separately, it may be as well to recall once more that in former lectures we have treated the apparent losses only as modifications in a negative way, without contemplating the underlying causes. Let us recall the cases of bud-atavism given by the whitish variety of the scarlet _Ribes_, by peaches and nectarines, and by conifers, including _Cephalotaxus_ and _Cryptomeria_. These and many other analogous facts go to prove the relation of the variety to the species. Two assumptions are allowable. In one the variety differs from the species by the total loss of the [227] distinctive character. In the other this character is simply reduced to an inactive or dormant state. The fact of its recurrence from time to time, accompanied by secondary characters previously exhibited, is a manifest proof of the existence of some relation between the lost and the resumed peculiarity. Evidently this relation cannot be accounted for on the assumption of an absolute disappearance; something must remain from which the old features may be restored. This lengthy discussion may be closed by the citation of the cases, in which plants not only show developmental features of a former state, but also reproduce the special features they formerly had, but seemingly have lost. Two good illustrative examples may be given. One is afforded by the wheat-ear carnation, the other by the green dahlias, and both have occurred of late in my own cultures. A very curious anomaly may from time to time be observed in large beds of carnations. It bears no flowers, but instead of them small green ears, which recall the ears of wheat. Thence the name of "Wheat-ear" carnation. On closer inspection it is easily seen how they originate. The normal flowers of the carnations are preceded by a small group of bracts, [228] which are arranged in opposite pairs and therefore constitute four rows. In this variety the flower is suppressed and this loss is attended by a corresponding increase of the number of the pairs of bracts. This malformation results in square spikes or somewhat elongated heads consisting only of the greenish bracts. As there are no flowers, the variety is quite sterile, and as it is not regarded by horticulturists as an improvement on the ordinary bright carnations, it is seldom multiplied by layering. Notwithstanding this, it appears from time to time and has been seen in different countries and at different periods, and, what is of great importance for us, in different strains of carnations. Though sterile, and obviously dying out as often as it springs into existence, it is nearly two centuries old. It was described in the beginning of the 18th century by Volckamer, and afterwards by Jaeger, De Candolle, Weber, Masters, Magnus and many other botanists. I have had it twice, at different times and from different growers. So far as I have been able to ascertain reversions of this curious carnation to normal flowers have not yet been recorded. Such a modification occurred last summer in my garden on a plant which had not been divided or layered, but on which the slender branches had [229] been left on the stem. Some of them remained true to the varietal type and bore only green spikes. Others reverted wholly or partially to the production of normal flowers. Some branches bore these only, others had spikes and flowers on neighboring twigs, and in still other instances little spikes had been modified in such manner that a more or less well developed flower was preceded by some part of an ear. The proof that this retrograde modification was due to the existence of a character in the latent state was given by the color of the flowers. If the reverted bud had only lost the power of producing spikes, they would evidently simply have returned to the characteristics of the ordinary species, and their color would have been a pale pink. Instead of this, all flowers displayed corollas of a deep brown. They obviously reverted to their special progenitor, the chance variety from which they had sprung, and not to the common prototype of the species. Of course it was not possible to ascertain from which variety the plant had really originated, but the reproduction of any one clearly defined varietal mark is in itself proof enough of their origin, and of the latency of the dark brown flower-color in this special case. A still better proof is afforded by a new type of green dahlia. The ordinary green dahlia [230] has large tufts of green bracts instead of flowering heads, the scales of the receptacle having assumed the texture and venation of leaves, and being in some measure as fleshy. But the green heads retain the form of the ordinary flower-heads, and as they have no real florets that may fade away, they remain unchanged on the plants, and increase in number through the whole summer. The new types of green dahlia however, with which I have now to deal, are distinguished by the elongation of the axis of the head, which is thereby changed into a long leafy stalk, attaining a length of several inches. These stalks continue growing for a very long time, and for the most part die without producing anything else than green fleshy scales. This long-headed green dahlia originated at Haarlem some years ago, in the nursery of Messrs. Zocher & Co. It was seen to arise twice, from different varieties. Both of these were double-flowered, one a deep carmine with white tips on the rays, the other of a pale orange tint, known by the name of "Surprise." As they did not bear any florets or seeds, they were quite sterile. The strain arising from the carmine variety was kindly given to me by Messrs. Zocher & Co., and was propagated in my garden, while the other was kept in the nursery. In the earlier cultures both remained true to [231] their types, never producing true florets. No mark of the original difference was to be seen between them. But last summer (1903) both reverted to their prototypes, bearing relatively large numbers of ordinary double flowerheads among the great mass of green stalks. Some intermediate forms also occurred consisting of green-scaled stalks ending in small heads with colored florets. Thus far we have an ordinary case of reversion. But the important side of the phenomenon was, that each plant exactly "recollected" from which parent it had sprung. All of those in my garden reverted to the carmine florets with white tips, and all of those in the nursery to the pale orange color and the other characteristics of the "Surprise" variety. It seems absolutely evident, that no simple loss can account for this difference. Something of the character of the parent-varieties must have remained in the plant. And whatever conception we may formulate of these vestigial characters it is clear that the simplest and most obvious idea is their preservation in a dormant or latent state. Assuming that the distinguishing marks have only become inactive by virescence, it is manifest that on returning each will show its own peculiarities, as recorded above. Our second point was the incomplete loss of [232] the distinguishing quality in some varieties. It is of general occurrence, though often overlooked. Many white varieties of colored flowers give striking instances, among them many of the most stable and most prized garden-flowers. If you look at them separately or in little bouquets they seem to be of irreproachable purity. But if you examine large beds a pale hue will become visible. In many cases this tinge is so slight as to be only noticeable in a certain illumination, or by looking in an oblique direction across the bed; in others it is at once evident as soon as it has been pointed out. It always reminds the observer of the color of the species to which the variety belongs, being bluish in violets and harebells, reddish in godetias and phloxes, in _Silene Armeria_ and many others. It proves that the original color quality of the species has not wholly, but only partly disappeared. It is dormant, but not entirely obliterated; latent, but not totally concealed; inactive, but only partially so. Our terminology is an awkward one; it practically assumes, as it so often does in other cases, a conventional understanding, not exactly corresponding to the simple meaning of the words. But it would be cumbrous to speak always of partial inactivity, incomplete latency or half awakening qualities. Even such words as sub-latent, [233] which would about express the real state of things, would have little chance of coming into general use. Such sub-latent colors are often seen on special parts in white varieties of flowers. In many cases it is the outer side of the petals which recalls the specific color, as in some white roses. In violets it is often on the spur that the remains of the original pigment are to be seen. In many instances it is on the tips of the petals or of the segments of the corolla, and a large number of white or yellow flowers betray their affinity to colored species by becoming red or bluish at the edges or on the outer side. The reality of such very slight hues, and their relation to the original pigment of the species may in some cases be proved by direct experiment. If it is granted that latency is not an absolute quality, then it will be readily accepted, that even latency must be subjected to the laws of gradual variation or fluctuating variability. We will deal with these laws in a later lecture but every one knows that greater deviations than the ordinary may be attained by sowing very large numbers and by selecting from among them the extreme individuals and sowing anew from their seed. In this way the slightest tinge of any latent color may be [234] strengthened, not indeed to the restoration of the tinge of the species, but at least so far as to leave no doubt as to the identity of the visible color of the species and the latent or sublatent one of the variety. I made such an experiment with the peach leaved harebell or _Campanula persicifolia_. The white variety of this species, which is often met with in our gardens, shows a very pale bluish hue when cultivated in large quantities, which however is subject to individual variations. I selected some plants with a decided tinge, flowered them separately, sowed their seeds, and repeated this during two generations. The result was an increase of the color on the tips of the segments of the corolla in a few individuals, most of them remaining as purely white as the original strain. But in those few plants the color was very manifest, individually variable in degree, but always of the same blue as in the species itself. Many other instances could be given. Smooth varieties are seldom absolutely so, and if scattering hairs are found on the leaves or only on some more or less concealed parts, they correspond in their character to those of the species. So it is with prickles, and even the thornless thorn-apple has fruits with surfaces far from smooth. The thornless horse-chestnut [235] has in some instances such evident protuberances on the valves of its fruits, that it may seem doubtful whether it is a pure and stable variety. Systematic latency may betray itself in different ways, either by normal systematic marks, or by atavism. With the latter I shall deal at length on another occasion, and therefore I will give here only one very clear and beautiful example. It is afforded by the common red clover. Obviously the clovers, with their three leaflets in each leaf, stand in the midst of the great family of papilionaceous plants, the leaves of which are generally pinnate. Systematic affinity suggests that the "three leaved" forms must have been derived from pinnate ancestors, evidently by the reduction of the number of the leaflets. In some species of clover the middle of the three is more or less stalked, as is ordinarily the case in pinnate leaves; in others it is as sessile as are its neighbors. In a subsequent chapter I will describe a very fine variety, which sometimes occurs in the wild state and may easily be isolated and cultivated. It is an ordinary red clover with five leaflets instead of three, and with this number varying between three and seven, instead of being nearly wholly stable as in the common form. It produces from time to time pinnate leaves, [236] very few indeed, and only rarely, but then often two or three or even more on the same individual. Intermediate stages are not wanting, but are of no consequence here. The pinnate leaves obviously constitute a reversion to some prototype, to some ancestor with ordinary papilionaceous leaves. They give proof of the presence of the common character of the family, concealed here in a latent state. Any other explanation of this curious anomaly would evidently be artificial. On the other hand nothing is really known about the ancestors of clover, and the whole conception rests only on the prevailing views of the systematic relationships in this family. But, as I have already said, further proof must be left for a subsequent occasion. Many instances, noted in our former lectures, could be quoted here. The systematic distribution of rayed and rayless species and varieties among the daisy-group of the composites affords a long series of examples. Accidental variations in both directions occur. The Canada fleabane or _Erigeron canadensis_, the tansy or _Tanacetum vulgare_ and some others may at times be seen with ray-florets, and according to Murr, they may sometimes be wanting in _Aster Tripolium_, _Bellis perennis_, some species of _Anthemis_, _Arnica montana_ and in a number [237] of other well-known rayed species. Another instance may be quoted; it has been pointed out by Grant Allen, and refers to the dead-nettle or Lamium album. Systematically placed in a genus with red-flowering species, we may regard its white color as due to the latency of the general red pigment. But if the flower of this plant is carefully examined, it will be found in most cases not to be purely white, but to have some dusky lines and markings on its lower lip. Similar devices are observed on the lip of the allied _Lamium maculatum_, and in a less degree on the somewhat distant _Lamium purpureum_. With _Lamium maculatum_ or spotted dead-nettle, the affinity is so close that even Bentham united the two in a single species, considering the ordinary dead-nettle only as a variety of the dappled purple type. For the support of this conception of a specific or varietal retrograde change many other facts are afforded by the distribution of the characteristic color and of the several patterns of the lips of other labiates, and our general understanding of the relationships of the species and genera in this family may in a broad sense be based on the comparison of these seemingly subordinate characteristics. The same holds good in many other cases, and systematists have often become uncertain [238] as to the true value of some form, by its relationship to the allied types in the way of retrogressive modification. Color-differences are so showy, that they easily overshadow other characters. The white and the blue thorn-apple, the white and the red campion (_Lychnis vespertina_ and _diurna_) and many other illustrative cases could be given, in which two forms are specifically separated by some authors, but combined by others on the ground of the retrograde nature of some differentiating mark. Hitherto we have dealt with negative characters and tried to prove that the conception of latency of the opposite positive characteristics is a more natural explanation of the phenomenon than the idea of a complete loss. We have now to consider the positive varieties, and to show that it is quite improbable that here the species have struck out for themselves a wholly new character. In some instances such may have been the case, but then I should prefer to treat these rather as elementary species. But in the main we will have to assume the latency of the character in the species and its reassumption by the variety when originating, as the most probable explanation. Great stress is laid upon this conception by the fact, that positive varieties are so excessively rare when compared with the common occurrence [239] of negative ones. Indeed, if we put aside the radiate and the color-varieties of flowers and foliage, hardly any cases can be cited. We have dealt with this question in a former lecture, and may now limit ourselves to the positive color-varieties. The latency of the faculty of producing the red pigment in leaves must obviously be accepted for nearly the whole vegetable kingdom. Oaks and elms, the beautiful climbing species of Ampelopsis, many conifers, as for instance _Cryptomeria japonica_, some brambles, the Guelder-rose (_Viburnum Opulus_) and many other trees and shrubs assume a more or less bright red color in the fall. During summer this tendency must have been dormant, and that this is so, is shown by the young leaves of oaks and others, which, when unfolding in the spring show a similar but paler hue. Moreover, there is a way of awakening the concealed powers at any time. We have only to inflict small wounds on the leaves, or to cut through the nerves or to injure them by a slight bruising, and the leaves frequently respond with an intense reddening of the living tissues around and especially above the wounds. _Azolla caroliniana_, a minute mosslike floating plant allied to the ferns, responds to light and cold with a reddish tinge, and to shade or warmth with a pure green. The foliage [240] of many other plants behaves likewise, as also do apples and peaches on the insolated sides of the fruits. It is quite impossible to state these groups of facts in a more simple way than by the statement that the tendency to become red is almost generally present, though latent in leaves and stems, and that it comes into activity whenever a stimulus provokes it. Now it must be granted that the energizing of such a propensity under ordinary circumstances is quite another thing from the origination of a positive variety by the evolution of the same character. In the variety the activity has become independent of outer influences or dependent upon them in a far lesser degree. The power of producing the red pigments is shown to be latent by the facts given above, and we see that in the variety it is no longer latent but is in perfect and lasting activity throughout the whole life of the plant. Red varieties of white flowers are much more rare. Here the latency of the red pigment may be deduced partly from general arguments like those just given, partly from the special systematic relations in the given cases. Hildebrand has clearly worked out this mode of proof. He showed by the critical examination of a large number of instances that the occurrence of the red-flowered varieties is contingent upon the [241] existence of red species in the same genus, or in some rare cases, in nearly allied genera. Colors that are not systematically present in the group to which a white species belongs are only produced in its varieties in extremely rare cases. We may quote some special rules, indicated by Hildebrand. Blue species are n the main very rare, and so are blue varieties of white species also. Carnations, Asiatic or cultivated buttercups (_Ranunculus asiaticus_), _Mirabilis_, poppies, _Gladiolus_, _Dahlia_, and some other highly cultivated or very old garden-plants have not been able to produce true blue flowers. But the garden-anemone (_Anemone coronaria_) has allies with very fine blue flowers. The common stock has bluish varieties and is allied to _Aubretia_ and _Hesperis_, and gooseberries have a red form, recalling the ordinary currant. In nearly all other instances of blue or red varieties every botanist will be able to point out some allied red or blue species, as an indication of the probable source of the varietal character. Dark spots on the lower parts of the petals of some plants afford another instance, as in poppies and in the allied _Glaucium_, where they sometimes occur as varietal and in other cases as specific marks. The yellow fails in many highly developed [242] flowers, which are not liable to produce yellow variations, as in _Salvia_, _Aster_, _Centaurea_, _Vinca_, _Polygala_ and many others. Even the rare pale yellowish species of some of these genera have no tendency in this direction. The hyacinths are the most remarkable, if not the sole known instance of a species having red and blue and white and yellow varieties, but here the yellow is not the bright golden color of the buttercups. The existence of varietal colors in allied species obviously points to a common cause, and this cause can be no other than the latency of the pigment in the species that do not show it. The conception of latency of characters as the common source of the origination of varieties, either in the positive or in the negative way, leads to some rules on variability, which are known under the names given to them by Darwin. They are the rules of repeated, homologous, parallel and analogous variability. Each of them is quite general, and may be recognized in instances from the most widely distant families. Each of them is quite evident and easily understood on the principle of latency. By the term of repeated variability is meant the well-known phenomenon, that the same variety has sprung at different times and in different [243] countries from the same species. The repetition obviously indicates a common internal cause. The white varieties of blue- and red-flowered plants occur in the wild state so often, and in most of the instances in so few individuals that a common pedigree is absolutely improbable. In horticulture this tendency is widely and vexatiously known, since the repetition of an old variety does not bring any advantage to the breeder. The old name of "conquests," given by the breeders of hyacinths, tulips and other flower-bulbs to any novelty, in disregard of the common occurrence of repetitions, is an indication of the same experience in the repeated appearance of certain varieties. The rule of parallel variations demands that the same character occasionally makes its appearance in the several varieties or races, descended from the same species, and even in widely distinct species. This is a rule, which is very important for the general conception of the meaning of the term variety as contrasted with elementary species. For the recurrence of the same deviation always impresses us as a varietal mark. Laciniated leaves are perhaps the most beautiful instance, since they occur in so many trees and shrubs, as the walnut tree, the beech, the birch, the hazelnut, and even in [244] brambles and some garden-varieties of the turnip (_Brassica_). In such cases of parallel variations the single instances obviously follow the same rules and are therefore to be designated as analogous. Pitchers or ascidia, formed by the union of the margins of a leaf, are perhaps the best proof. They were classified by Morren under two heads, according to their formation from one or more leaves. Monophyllous pitchers obey the same law, viz.: that the upper side of the leaf has become the inner side of the pitcher. Only one exception to this rule is known to me. It is afforded by the pitchers of the banyan or holy fig-tree, _Ficus religiosus_, but it does not seem to belong to the same class as other pitchers, since as far as it has been possible to ascertain the facts, these pitchers are not formed by a few leaves as in all other cases, but by all the leaves of the tree. In some cases pitchers are only built up of part of the leaf-blade. Such partial malformations obey a rule, that is common to them and to other foliar enations, viz.: that the side of the leaf from which they emerge, is always their outer side. The inner surface of these enations corresponds to the opposite side of the leaf, both in color and in anatomical structure. The last of the four rules above mentioned is [245] that of the homologous variability. It asserts that the same deviation may occur in different, but homologous parts of the same plant. We have already dealt with some instances, as the occurrence of the same pigment in the flowers and foliage, in the fruits and seeds of the same plant, as also illustrated by the loss of the red or blue tinge by flowers and berries. Other instances are afforded by the curious fact that the division of the leaves into numerous and small segments is repeated by the petals, as in the common celandine and some sorts of brambles. It would take too long to make a closer examination of the numerous cases which afford proof of these statements. Suffice it to say that everywhere the results of close inspection point to the general rule, that the failure of definite qualities both in species and in varieties must, in a great number of cases, be considered as only apparent. Hidden from view, occasionally reappearing, or only imperfectly concealed, the same character must be assumed to be present though latent. In the case of negative or retrogressive varieties it is the transition from the active into a dormant state to which is due the origin of the variety. Positive varieties on the contrary owe their origin to the presence of some character [246] in the species in the latent state, and to the occasional re-energizing thereof. Specific or varietal latency is not the same thing as the ordinary latency of characters that only await their period of activity, or the external influence which will awake them. They are permanently latent, and could well be designated by the word perlatent. They spring into activity only by some sudden leap, and then at once become independent of ordinary external stimulation. [247] LECTURE IX CROSSES OF SPECIES AND VARIETIES In the foregoing lectures I have tried to show that there is a real difference between elementary species and varieties. The first are of equal rank, and together constitute the collective or systematic species. The latter are usually derived from real and still existing types. Elementary species are in a sense independent of each other, while varieties are of a derivative nature. Furthermore I have tried to show that the ways in which elementary or minor species must have originated from their common ancestor must be quite different from the mode of origin of the varieties. We have assumed that the first come into existence by the production of something new, by the acquirement of a character hitherto unnoticed in the line of their ancestors. On the contrary, varieties, in most cases, evidently owe their origin to the loss of an already existing character, or in other less frequent cases, to the re-assumption of a quality [248] formerly lost. Some may originate in a negative, others in a positive manner, but in both cases nothing really new is acquired. This distinction holds good for all cases in which the relationship between the forms in question is well known. It seems entirely justifiable therefore to apply it also to cases in which the systematic affinity is doubtful, as well as to instances in which it is impossible to arrive at any taxonomic conclusions. The extreme application of the principle would no doubt disturb the limits between many species and varieties as now recognized. It is not to be forgotten however that all taxonomic distinctions, which have not been confirmed by physiologic tests are only provisional, a view acknowledged by the best systematists. Of course the description of newly discovered forms can not await the results of physiologic inquiries; but it is absolutely impossible to reach definite conclusions on purely morphologic evidence. This is well illustrated by the numerous discords of opinion of different authors on the systematic worth of many forms. Assuming the above mentioned principle as established, and disregarding doubtful cases as indicated, the term progressive evolution is used to designate the method in which elementary species must have originated. It is the [249] manner in which all advance in the animal and vegetable kingdoms must have taken place, continuously adding new characters to the already existing number. Contrasted with this method of growing differentiation, are the retrogressive modifications, which simply retrace a step, and the degressive changes in which a backward step is retraced and old characters revived. No doubt both of these methods have been operative on a large scale, but they are evidently not in the line of general advancement. In all of these directions we see that the differentiating marks show more or less clearly that they are built up of units. Allied forms are separated from each other without intermediates. Transitions are wholly wanting, although fallaciously apparent in some instances owing to the wide range of fluctuating variability of the forms concerned, or to the occurrence of hybrids and subvarieties. These physiologic units, which in the end must be the basis for the distinction of the systematic units, may best be designated by the term of "unit-characters." Their internal nature is as yet unknown to us, and we will not now look into the theories, which have been propounded as to the probable material basis underlying them. For our present purpose the empirical evidence of the general occurrence of [250] sharp limits between nearly related characters must suffice. As Bateson has put it, species are discontinuous, and we must assume that their characters are discontinuous also. Moreover there is as yet no reason for trying to make a complete analysis of all the characters of a plant. No doubt, if attained, such an analysis would give us a deep insight into the real internal construction of the intricate properties of organisms in general. But taxonomic studies in this direction are only in their infancy and do not give us the material required for such an analysis. Quite on the contrary, they compel us to confine our study to the most recently acquired, or youngest characters, which constitute the differentiating marks between nearly allied forms. Obviously this is especially the case in the realm of the hybrids, since only nearly related forms are able to give hybrid offspring. In dealing with this subject we must leave aside all questions concerning more remote relationships. It is not my purpose to treat of the doctrine of hybridization at any length. Experience is so rapidly increasing both in a practical and in a purely scientific direction that it would take an entire volume to give only a brief survey of the facts and of all the proposed theories. [251] For our present purposes we are to deal with hybrids only in so far as they afford the means of a still better distinction between elementary species and varieties. I will try to show that these two contrasting groups behave in quite a different manner, when subjected to crossing experiments, and that the hope is justified that some day crosses may become the means of deciding in any given instance, what is to be called a species, and what a variety, on physiologic grounds. It is readily granted that the labor required for such experiments, is perhaps too great for the results to be attained, but then it may be possible to deduce rules from a small series of experiments, which may lead us to a decision in wider ranges of cases. To reach such a point of view it is necessary to compare the evidence given by hybrids, with the conclusions already attained by the comparison of the differentiating characteristics of allied forms. On this ground we first have to inquire what may be expected respecting the internal nature and the outcome of the process of crossing in the various cases cited in our former discussion. We must always distinguish the qualities, which are the same in both parents, from those that constitute the differentiating marks in every single cross. In respect to the first [252] group the cross is not at all distinguished from a normal fertilization, and ordinarily these characters are simply left out of consideration. But it should never be forgotten that they constitute the enormous majority, amounting to hundreds and thousands, whereas the differentiating marks in each case are only one or two or a few at most. The whole discussion is to be limited to these last-named exceptions. We must consider first what would be the nature of a cross when species are symmetrically combined, and what must be the case when varieties are subjected to the same treatment. In so doing, I intend to limit the discussion to the most typical cases. We may take the crosses between elementary species of the same or of very narrowly allied systematic species on the one side, and on the other, limit treatment to the crossing of varieties with the species, from which they are supposed to have sprung by a retrograde modification. Crosses of different varieties of the same species with one another obviously constitute a derivative case, and should only be discussed secondarily. And crosses of varieties with positive or depressive characters have as yet so rarely been made that we may well disregard them. Elementary species differ from their nearest allies by progressive changes, that is by the acquirement [253] of some new character. The derivative species has one unit more than the parent. All other qualities are the same as in the parent. Whenever such a derivative is combined with its parent the result for these qualities will be exactly as in a normal fertilization. In such ordinary cases it is obvious that each character of the pollen-parent is combined with the same character of the pistil-parent. There may be slight individual differences, but each unit character will become opposed to, and united with, the same unit-character in the other parent. In the offspring the units will thus be paired, each pair consisting of two equivalent units. As to their character the units of each single pair are the same, only they may exhibit slight differences as to the degree of development of this character. Now we may apply this conception to the sexual combination of two different elementary species, assuming one to be the derivative of the other. The differentiating mark is only present in one of the parents and wanting in the other. While all other units are paired in the hybrid, this one is not. It meets with no mate, and must therefore remain unpaired. The hybrid of two such elementary species is in some way incomplete and unnatural. In the ordinary course of things all individuals derive [254] their qualities from both parents; for each single mark they possess at least two units. Practically but not absolutely equal, these two opponents always work together and give to the offspring a likeness to both parents. No unpaired qualities occur in normal offspring; these constitute the essential features of the hybrids of species and are at the same time the cause of their wide deviations from the ordinary rules. Turning now to the varieties, we likewise need discuss their differentiating marks only. In the negative types, these consist of the apparent loss of some quality which was active in the species. But it was pointed out in our last lecture that such a change is an apparent loss. On a closer inquiry we are led to the assumption of a latent or dormant state. The presumably lost characters have not absolutely, or at least not permanently disappeared. They show their presence by some slight indication of the quality they represent, or by occasional reversions. They are not wanting, but only latent. Basing our discussion concerning the process of crossing on this conception, and still limiting the discussion to one differentiating mark, we come to the inference, that this mark is present and active in the species, and present but dormant in the variety. Thus it is present in both, and as all other characters not differentiating [255] find their mates in the cross, so these two will also meet one another. They will unite just as well as though they were both active or both dormant. For essentially they are the same, only differing in their degree of activity. From this we can infer, that in the crossing of varieties, no unpaired remainder is left, all units combining in pairs exactly as in ordinary fertilization. Setting aside the contrast between activity and latency in this single pair, the procedure in the inter-crossing of varieties is the same as in ordinary normal fertilization. Summarizing this discussion we may conclude that in normal fertilization and in the inter-crossing of varieties all characters are paired, while in crosses between elementary species the differentiating marks are not mated. In order to distinguish these two great types of fertilization we will use the term bisexual for the one and unisexual for the other. The term balanced crosses then conveys the idea of complete bisexuality, all unit-characters combining in pairs. Unbalanced crosses are those in which one or more units do not find their mates and therefore remain unpaired. This distinction was proposed by Macfarlane when studying the minute structure of plant-hybrids in comparison with that of their parents (1892). [256] In the first place it shows that a species hybrid may inherit the distinguishing marks of both parents. In this way it may become intermediate between them, having some characters in common with the pollen-parent and others with the pistil-parent. As far as these characters do not interfere with each other, they may be fully developed side by side, and in the main this is the way in which hybrid characters are evolved. But in most cases our existing knowledge of the units is far too slender to give a complete analysis, even of these distinguishing marks alone. We recognize the parental marks more or less clearly, but are not prepared for exact delimitations. Leaving these theoretical considerations, we will pass to the description of some illustrative examples. In the first place I will describe a hybrid between two species of _Oenothera_, which I made some years ago. The parents were the common evening-primrose or _Oenothera biennis_ and of its small-flowered congener, _Oenothera muricata_. These two forms were distinguished by Linnaeus as different species, but have been considered by subsequent writers as elementary species or so-called systematic varieties of one species designated with the name of the presumably older type, the _O. biennis_. Varietal differences in a physiologic sense they [257] do not possess, and for this reason afford a pure instance of unbalanced union, though differing in more than one point. I have made reciprocal crosses, taking at one time the small-flowered and at the other the common species as pistillate parent. These crosses do not lead to the same hybrid as is ordinarily observed in analogous cases; quite on the contrary, the two types are different in most features, both resembling the pollen-parent far more than the pistil-parent. The same curious result was reached in sundry other reciprocal crosses between species of this genus. But I will limit myself here to one of the two hybrids. In the summer of 1895 I castrated some flowers of _O. muricata_, and pollinated them with _O. biennis_, surrounding the flowers with paper bags so as to exclude the visits of insects. I sowed the seeds in 1896 and the hybrids were biennial and flowered abundantly the next year and were artificially fertilized with their own pollen, but gave only a very small harvest. Many capsules failed, and the remaining contained only some few ripe seeds. From these I had in the following year the second hybrid generation, and in the same way I cultivated also the third and fourth. These were as imperfectly fertile as the first, and in [258] some years did not give any seed at all, so that the operation had to be repeated in order to continue the experiment. Last summer (1903) I had a nice lot of some 25 biennial specimens blooming abundantly. All in all I have grown some 500 hybrids, and of these about 150 specimens flowered. These plants were all of the same type, resembling in most points the pollen-parent, and in some others the pistil-parent of the original cross. The most obvious characteristic marks are afforded by the flowers, which in _O. muricata_ are not half so large as in _biennis_, though borne by a calyx-tube of the same length. In this respect the hybrid is like the _biennis_ bearing the larger flowers. These may at times seem to deviate a little in the direction of the other parent, being somewhat smaller and of a slightly paler color. But it is very difficult to distinguish between them, and if _biennis_ and hybrid flowers were separated from the plants and thrown together, it is very doubtful whether one would succeed in separating them. The next point is offered by the foliage. The leaves of _O. biennis_ are broad, those of _O. muricata_ narrow. The hybrid has the broad leaves of _O. biennis_ during most of its life and at the time of flowering. Yet small deviations in the [259] direction of the other parent are not wanting, and in winter the leaves of the hybrid rosettes are often much narrower than those of _O. biennis_, and easily distinguishable from both parents. A third distinction consists in the density of the spike. The distance between the insertion of the flowers of _O. biennis_ is great when compared with that of _O. muricata_. Hence the flowers of the latter species are more crowded and those of _O. biennis_ more dispersed, the spikes of the first being densely crowned with flowers and flower-buds while those of _O. biennis_ are more elongated and slender. As a further consequence the _O. biennis_ opens on the same evening only one, two or three flowers on the same spike, whereas _O. muricata_ bears often eight or ten or more flowers at a time. In this respect the hybrid is similar to the pistil-parent, and the crowding of the broad flowers at the top of the spikes causes the hybrids to be much more showy than either of the parent types. Other distinguishing marks are not recorded by the systematists, or are not so sharply separated as to allow of the corresponding qualities of the hybrids being compared with them. This hybrid remains true to the description given. In some years I cultivated two generations [260] so as to be able to compare them with one another, but did not find any difference. The most interesting point however, is the likeness between the first generation, which obviously must combine in its internal structure the units of both parents, and the second and later generations which are only of a derivative nature. Next to this stands the fact that in each generation all individuals are alike. No reversion to the parental forms either in the whole type or in the single characteristics has ever been observed, though the leaves of some hundreds, and the spikes and flowers of some 150 individual plants have been carefully examined. No segregation or splitting up takes place. Here we have a clear, undoubted and relatively simple, case of a true and pure species hybrid. No occurrence of possible varietal characteristics obscures the result, and in this respect this hybrid stands out much more clearly than all those between garden-plants, where varietal marks nearly always play a most important part. From the breeder's point of view our hybrid _Oenothera_ would be a distinct gain, were it not for the difficulty of its propagation. But to enlarge the range of the varieties this simple and stable form would need to be treated anew, by [261] crossing it with the parent-types. Such experiments however, have miscarried owing to the too stable nature of the unit-characters. This stability and this absence of the splitting shown by varietal marks in the offspring of hybrids is one of the best proofs of unisexual unions. It is often obscured by the accompanying varietal marks, or overlooked for this reason. Only in rare cases it is to be met with in a pure state and some examples are given of this below. Before doing so, I must call your attention to another feature of the unbalanced unions. This is the diminution of the fertility, a phenomenon universally known as occurring in hybridizations. It has two phases. First, the diminished chance of the crosses themselves of giving full crops of seed, as compared with the pure fertilization of either parent. And, secondly, the fertility of the hybrids themselves. Seemingly, all grades of diminished fertility occur and the oldest authors on hybrids have pointed out that a very definite relation exists between the differences of the parents and the degree of sterility, both of the cross and of the hybrid offspring. In a broad sense these two factors are proportionate to each other, the sterility being the greater, the lesser the affinity between the parents. Many writers have [262] tried to trace this rule in the single cases, but have met with nearly unsurmountable difficulties, owing chiefly to our ignorance of the units which form the differences between the parents in the observed cases. In the case of _Oenothera muricata x biennis_ the differentiating units reduce the fertility to a low degree, threatening the offspring with almost complete infertility and extinction. But then we do not know whether these characters are really units, or perhaps only seemingly so and are in reality composed of smaller entities which as yet we are not able to segregate. And as long as we are devoid of empirical means of deciding such questions, it seems useless to go farther into the details of the question of the sterility. It should be stated here however, that pure varietal crosses, when not accompanied by unbalanced characters, have never showed any tendency to diminished fertility. Hence there can be little doubt that the unpaired units are the cause of this decrease in reproductive power. The genus _Oenothera_ is to a large degree devoid of varietal characteristics, especially in the subgenus _Onagra_, to which _biennis_, _muricata_, _lamarckiana_ and some others belong. On the other hand it seems to be rich in elementary species, but an adequate study of [263] them has as yet not been made. Unfortunately many of the better systematists are in the habit of throwing all these interesting forms together, and of omitting their descriptive study. I have made a large number of crosses between such undescribed types and as a rule got constant hybrid races. Only one or two exceptions could be quoted, as for instance the _Oenothera brevistylis_, which in its crosses always behaves as a pure retrogressive variety. Instead of giving an exhaustive survey of hybrids, I simply cite my crosses between _lamarckiana_ and _biennis_, as having nearly the aspect of the last named species, and remaining true to this in the second generation without any sign of reversion or of splitting. I have crossed another elementary species, the _Oenothera hirtella_ with some of my new and with some older Linnean species, and got several constant hybrid races. Among these the offspring of a cross between _muricata_ and _hirtella_ is still in cultivation. The cross was made in the summer of 1897 and last year (1903) I grew the fourth generation of the hybrids. These had the characters of the _muricata_ in their narrow leaves, but the elongated spikes and relatively large flowers of the _hirtella_ parent, and remained true to this type, showing only slight fluctuations and never reverting or segregating [264] the mixed characters. Both parents bear large capsules with an abundance of seed, but in the hybrids the capsules remain narrow and weak, ripening not more than one-tenth the usual quantity of seed. Both parents are easily cultivated in annual generations and the same holds good for the hybrid. But whereas the hybrid of muricata and biennis is a stout plant, this type is weak with badly developed foliage, and very long strict spikes. Perhaps it was not able to withstand the bad weather of the last few years. A goodly number of constant hybrids are described in literature, or cultivated in fields and gardens. In such cases the essential question is not whether they are now constant, but whether they have been so from the beginning, or whether they prove to be constant whenever the original cross is repeated. For constant hybrids may also be the issue of incipient splittings, as we shall soon see. Among other examples we may begin with the hybrid alfalfa or hybrid lucerne (_Medicago media_). It often originates spontaneously between the common purple lucerne or alfalfa and its wild ally with yellow flowers and procumbent stems, the _Medicago falcata_. This hybrid is cultivated in some parts of Germany on a large scale, as it is more productive than [265] the ordinary lucerne. It always comes true from seed and may be seen in a wild state in parks and on lawns. It is one of the oldest hybrids with a pure and known lineage. The original cross has been repeated by Urban, who found the hybrid race to be constant from the beginning. Another very notorious constant hybrid race is the _Aegilops speltaeformis_. It has been cultivated in botanic gardens for more than half a century, mostly in annual or biennial generations. It is sufficiently fertile and always comes true. Numerous records have been made of it, since formerly it was believed by Fabre and others to be a spontaneous transition from some wild species of grass to the ordinary wheat, not a cross. Godron, however, showed that it can be produced artificially, and how it has probably sprung into existence wherever it is found wild. The hybrid between _Aegilops ovata_, a small weed, and the common wheat is of itself sterile, producing no good pollen. But it may be fertilized by the pollen of wheat and then gives rise to a secondary hybrid, which is no other than the _Aegilops speltaeformis_. This remained constant in Godron's experiments during a number of generations, and has been constant up to the present time. [266] Constant hybrids have been raised by Millardet between several species of strawberries. He combined the old cultivated forms with newly discovered types from American localities. They ordinarily showed only the characteristics of one of their parents and did not exhibit any new combination of qualities, but they came true to this type in the second and later generations. In the genus _Anemone_, Janczewski obtained the same results. Some characters of course may split, but others remain constant, and when only such are present, hybrid races result with new combinations of characters, which are as constant as the best species of the same genus. The hybrids of Janczewski were quite fertile, and he points out that there is no good reason why they should not be considered as good new species. If they had not been produced artificially, but found in the wild state, their origin would have been unknown, and there can be no doubt that they would have been described by the best systematists as species of the same value as their parents. Such is especially the case with a hybrid between _Anemone magellanica_ and the common _Anemone sylvestris_. Starting from similar considerations Kerner von Marilaun pointed out the fact long ago that many so-called species, of rare occurrence, [267] standing between two allied types, may be considered to have originated by a cross. Surely a wide field for abuse is opened by such an assertion, and it is quite a common habit to consider intermediate forms as hybrids, on the grounds afforded by their external characters alone, and without any exact knowledge of their real origin and often without knowing anything as to their constancy from seed. All such apparent explanations are now slowly becoming antiquated and obsolete, but the cases adduced by Kerner seem to stand this test. Kerner designates a willow, _Salix ehrhartiana_ as a constant hybrid between _Salix alba_ and _S. pentandra_. _Rhododendron intermedium_ is an intermediate form between the hairy and the rusty species from the Swiss Alps, _R. hirsutum_ and _R. ferrugineum_, the former growing on chalky, and the other on silicious soils. Wherever both these types of soil occur in the same valley and these two species approach one another, the hybrid _R. intermedium_ is produced, and is often seen to be propagating itself abundantly. As is indicated by the name, it combines the essential characters of both parents. _Linaria italica_ is a hybrid toad-flax between _L. genistifolia_ and _L. vulgaris_, a cross which I have repeated in my garden. _Drosera obovata_ [268] is a hybrid sundew between _D. anglica_ and _D. rotundifolia_. _Primula variabilis_ is a hybrid between the two common primroses, _P. officinalis_ and _P. grandiflora_. The willow-herb (_Epilobium_), the self-heal (_Brunella_) and the yellow pond-lilies (Nuphar) afford other instances of constant wild hybrids. Macfarlane has discovered a natural hybrid between two species of sundew in the swamps near Atco, N.J. The parents, _D. intermedia_ and _D. filiformis_, were growing abundantly all around, but of the hybrid only a group of eleven plants was found. A detailed comparison of the hybrid with its parents demonstrated a minute blending of the anatomical peculiarities of the parental species. Luther Burbank of Santa Rosa, California, has produced a great many hybrid brambles, the qualities of which in many respects surpass those of the wild species. Most of them are only propagated by cuttings and layers, not being stable from seed. But some crosses between the blackberry and the raspberry (_R. fruticosus_ and _R. idaeus_) which bear good fruit and have become quite popular, are so fixed in their type as to reproduce their composite characters from seed with as much regularity as the species of _Rubus_ found in nature. Among them are the "Phenomenal" and the [269] "Primus." The latter is a cross between the Californian dewberry and the Siberian raspberry and is certainly to be regarded as a good stable species, artificially produced. Bell Salter crossed the willow-herbs _Epilobium tetragonum_ and _E. montanum_, and secured intermediate hybrids which remained true to their type during four successive generations. Other instances might be given. Many of them are to be found in horticultural and botanical journals which describe their systematic and anatomical details. The question of stability is generally dealt with in an incidental manner, and in many cases it is difficult to reach conclusions from the facts given. Especially disturbing is the circumstance that from a horticultural point of view it is quite sufficient that a new type should repeat itself in some of its offspring to be called stable, and that for this reason absolute constancy is rarely proved. The range of constant hybrids would be larger by far were it not for two facts. The first is the absolute sterility of so many beautiful hybrids, and the second is the common occurrence of retrogressive characters among cultivated plants. To describe the importance of both these groups of facts would take too much [270] time, and therefore it seems best to give some illustrative examples instead. Among the species of _Ribes_ or currant, which are cultivated in our gardens, the most beautiful are without doubt the Californian and the Missouri currant, or _Ribes sanguineum_ and _R. aureum_. A third form, often met with, is "Gordon's currant," which is considered to be a hybrid between the two. It has some peculiarities of both parents. The leaves have the general form of the Californian parent, but are as smooth as the Missouri species. The racemes or flower-spikes are densely flowered as in the red species, but the flowers themselves are of a yellow tinge, with only a flesh-red hue on the outer side of the calyx. It grows vigorously and is easily multiplied by cuttings, but it never bears any fruit. Whether it would be constant, if fertile, is therefore impossible to decide. _Berberis ilicifolia_ is considered as a hybrid between the European barberry (_B. vulgaris_) and the cultivated shrub _Mahonia aquifolia_. The latter has pinnate leaves, the former undivided ones. The hybrid has undivided leaves which are more spiny than those of the European parent, and which are not deciduous like them, but persist during the winter, a peculiarity inherited from the _Mahonia_. As far as I [271] have been able to ascertain, this hybrid never produces seed. Another instance of an absolutely sterile hybrid is the often quoted _Cytisus adami_. It is a cross between the common laburnum (_Cytisus Laburnum_) and another species of the same genus, _C. purpureus_, and has some traits of both. But since the number of differentiating marks is very great in this case, most of the organs have become intermediate. It is absolutely sterile. But it has the curious peculiarity of splitting in a vegetative way. It has been multiplied on a large scale by grafting and was widely found in the parks and gardens of Europe during the last century. Nearly all these specimens reverted from time to time to the presumable parents. Not rarely a bud of Adam's laburnum assumed all the qualities of the common laburnum, its larger leaves, richer flowered racemes, large and brightly yellow flowers and its complete fertility. Other buds on the same tree reverted to the purple parent, with its solitary small flowers, its dense shrublike branches and very small leaves. These too are fertile, though not producing their seeds as abundantly as the _C. Laburnum_ reversions. Many a botanist has sown the seeds of the latter and obtained only pure common _C. Laburnum_ plants. I had a lot of nearly a hundred seedlings [272] myself, many of which have already flowered, bearing the leaves and flowers of the common species. Seeds of the purple reversions have also been sown, and also yielded the parental type only. Why this most curious hybrid sports so regularly and why others always remain true to their type is as yet an open question. But recalling our former consideration of this subject the supposition seems allowable that the tendency to revert is not connected with the type of the hybrid, but is apt to occur in some rare individuals of every type. But since most of the sterile hybrids are only known to us in a single individual and its vegetative offspring, this surmise offers an explanation of the rare occurrence of sports. Finally, we must consider some of the so called hybrid races or strains of garden-plants. _Dahlia_, _Gladiolus_, _Amaryllis_, _Fuchsia_, _Pelargonium_ and many other common flowers afford the best known instances. Immeasurable variability seems here to be the result of crossing. But on a closer inspection the range of characters is not so very much wider in these hybrid races than in the groups of parent species which have contributed to the origin of the hybrids. Our tuberous begonias owe their variability to at least seven original parent species, [273] and to the almost incredible number of combinations which are possible between their characters. The first of these crosses was made in the nursery of Veitch and Sons near London by Seden, and the first hybrid is accordingly known as _Begonia sedeni_ and is still to be met with. It has been superseded by subsequent crosses between the _sedeni_ itself and the _Veitchi_ and _rosiflora_, the _davisii_, the _clarkii_ and others. Each of them contributed its advantageous qualities, such as round flowers, rosy color, erect flower stalks, elevation of the flowers above the foliage and others. New crosses are being made continuously, partly between the already existing hybrids and partly with newly introduced wild species. Only rarely is it possible to get pure seeds, and I have not yet been able to ascertain whether the hybrids would come true from seed. Specific and varietal characters may occur together in many of the several forms, but nothing is as yet accurately known as to their behavior in pure fertilizations. Constancy and segregation are thrown together in such a manner that extreme variability results, and numerous beautiful types may be had, and others may be expected from further crosses. For a scientific analysis, however, the large range of recorded facts and the written history, which at first sight [274] seems to have no lacunae, are not sufficient. Most of the questions remain open and need investigation. It would be a capital idea to try to repeat the history of the begonias or any other hybrid race, making all the described crosses and then recording the results in a manner requisite for complete and careful scientific investigations. Many large genera of hybrid garden-flowers owe their origin to species rich in varieties or in elementary subspecies. Such is the case with the gladiolus and the tulips. In other cases the original types have not been obtained from the wild state but from the cultures of other countries. The dahlias were cultivated in Mexico when first discovered by Europeans, and the chrysanthemums have been introduced from the old gardens of Japan. Both of them consisted of various types, which afterwards have been increased chiefly by repeated intercrossing. The history of many hybrid races is obscure, or recorded by different authorities in a different way. Some have derived their evidence from one nursery, some from another, and the crosses evidently may have been different in different places. The early history of the gladiolus is an instance. The first crosses are recorded to have been made between _Gladiolus_ [275] _psittacinus_ and _G. cardinalis_, and between their hybrid, which is still known under the name of gandavensis_ and the _purpureo-auratus_. But other authors give other lines of descent. So it is with _Amaryllis_, which is said by De Graaff to owe its stripes to _A. vittata_, its fine form to _A. brasiliensis_, the large petals to _A. psittacina_, the giant flowers to _A. leopoldi_, and the piebald patterns to _A. pardina_. But here, too, other authors give other derivations. Summarizing the results of our inquiry we see in the first place how very much remains to be done. Many old crosses must be repeated and studied anew, taking care of the purity of the cross as well as of the harvesting of the seeds. Many supposed facts will be shown to be of doubtful validity. New facts have to be gathered, and in doing so the distinction between specific and varietal marks must be taken strictly into account. The first have originated as progressive mutations; they give unbalanced crosses with a constant offspring, as far as experience now goes. The second are chiefly due to retrograde modifications, and will be the subject of the next lecture. [276] LECTURE X MENDEL'S LAW OF BALANCED CROSSES In the scientific study of the result of crosses, the most essential point is the distinction of the several characters of the parents in their combination in the hybrids and their offspring. From a theoretical point of view it would be best to choose parents which would differ only in a single point. The behavior of the differentiating character might then easily be seen. Unfortunately, such simple cases do not readily occur. Most species, and even many elementary species are distinguished by more than one quality. Varieties deviating only in one unit-character from the species, are more common. But a closer inspection often reveals some secondary characters which may be overlooked in comparative or descriptive studies, but which reassume their importance in experimental crossings. In a former lecture we have dealt with the qualities which must be considered as being due to the acquisition of new characters. If we [277] compare the new form in this case with the type from which it has originated, it may be seen that the new character does not find its mate, or its opposite, and it will be unpaired in the hybrid. In the case of retrogressive changes the visible modification is due, at least in the best known instances, to the reduction of an active quality to a state of inactivity or latency. Now if we make a cross between a species and its variety, the differentiating character will be due to the same internal unit, with no other difference than that it is active in the species and latent in the variety. In the hybrid these two corresponding units will make a pair. But while all other pairs in the same hybrid individuals consist of like antagonists, only this pair consists of slightly unlike opponents. This conception of varietal crosses leads to three assertions, which seem justifiable by actual experience. First, there is no reason for a diminution of the fertility, as all characters are paired in the hybrid, and no disturbance whatever ensues in its internal structure. Secondly, it is quite indifferent, how the two types are combined, or which of them is chosen as pistillate and which as staminate parent. The deviating pair will have the same constitution in both cases, being [278] built up of one active and one dormant unit. Thirdly this deviating pair will exhibit the active unit which it contains, and the hybrid will show the aspect of the parent in which the character was active and not that of the parent in which it was dormant. Now the active quality was that of the species, and its latent state was found in the variety. Hence the inference that hybrids between a species and its retrograde variety will bear the aspect of the species. This attribute may be fully developed, and then the hybrid will not be distinguishable from the pure species in its outer appearance. Or the character may be incompletely evolved, owing to the failure of cooperation of the dormant unit. In this case the hybrid will be in some sense intermediate between its parents, but these instances are more rare than the alternate ones, though presumably they may play an important part in the variability of many hybrid garden-flowers. All of these three rules are supported by a large amount of evidence. The complete fertility of varietal hybrids is so universally acknowledged that it is not worth while to give special instances. With many prominent systematists it has become a test between species and varieties, and from our present point of view this assumption is correct. Only the test is of little use in practice, as fertility may be diminished [279] in unbalanced unions in all possible degrees, according to the amount of difference between the parents. If this amount is slight, if for instance, only one unit-character causes the difference, the injury to fertility may, be so small as to be practically nothing. Hence we see that this test would not enable us to judge of the doubtful cases, although it is quite sufficient as a proof in cases of wider differences. Our second assertion related to the reciprocal crosses. This is the name given to two sexual combinations between the same parents, but with interchanged places as to which furnishes the pollen. In unbalanced crosses of the genus _Oenothera_ the hybrids of such reciprocal unions are often different, as we have previously shown. Sometimes both resemble the pollen parent more, in other instances the pistil-parent. In varietal crosses no such divergence is as yet known. It would be quite superfluous to adduce single cases as proofs for this rule, which was formerly conceived to hold good for hybrids in general. The work of the older hybridists, such as Koelreuter and Gaertner affords numerous instances. Our third rule is of a wholly different nature. Formerly the distinction between elementary species and varieties was not insisted upon, and the principle which stamps retrograde changes [280] as the true character of varieties is a new one. Therefore it is necessary to cite a considerable amount of evidence in order to prove the assertion that a hybrid bears the active character of its parent-species and not the inactive character of the variety chosen for the cross. We may put this assertion in a briefer form, stating that the active character prevails in the hybrid over its dormant antagonist. Or as it is equally often put, the one dominates and the other is recessive. In this terminology the character of the species is dominant in the hybrid while that of the variety is recessive. Hence it follows that in the hybrid the latent or dormant unit is recessive, but it does not follow that these three terms have the same meaning, as we shall see presently. The term recessive only applies to the peculiar state into which the latent character has come in the hybrid by its pairing with the antagonistic active unit. In the first place it is of the highest importance to consider crosses between varieties of recorded origin and the species from which they have sprung. When dealing with mutations of celandine we shall see that the laciniated form originated from the common celandine in a garden at Heidelberg about the year 1590. Among my _Oenotheras_ one of the eldest of the recent productions is the _O. brevistylis_ or short [281] styled species which was seen for the first time in the year 1889. The third example offered is a hairless variety of the evening campion, _Lychnis vespertina_, found the same year, which hitherto had not been observed. For these three cases I have made the crosses of the variety with the parent-species, and in each case the hybrid was like the species, and not like the variety. Nor was it intermediate. Here it is proved that the older character dominates the younger one. In most cases of wild, and of garden-varieties, the relation between them and the parent-species rests upon comparative evidence. Often the variety is known to be younger, in other cases it may be only of local occurrence, but ordinarily the historic facts about its origin have never been known or have long since been forgotten. The easiest and most widely known varietal crosses are those between varieties with white flowers and the red- or blue-flowered species. Here the color prevails in the hybrid over the lack of pigment, and as a rule the hybrid is as deeply tinted as the species itself, and cannot be distinguished from it, without an investigation of its hereditary qualities. Instances may be cited of the white varieties of the snapdragon, of the red clover, the long-spurred violet (_Viola_ [282] _cornuta_) the sea-shore aster (_Aster Tripolium_), corn-rose (_Agrostemma Githago_), the Sweet William (_Silene Armeria_), and many garden flowers, as for instance, the _Clarkia pulchella_, the _Polemonium coeruleum_, the _Veronica longifolia_, the gloxinias and others. If the red hue is combined with a yellow ground-color in the species, the variety will be yellow and the hybrid will have the red and yellow mixture of the species as for instance, in the genus _Geum_. The toad-flax has an orange-colored palate, and a variety occurs in which the palate is of the same yellow tinge as the remaining parts of the corolla. The hybrid between them is in all respects like the parent-species. Other instances could be given. In berries the same rule prevails. The black nightshade has a variety with yellow berries, and the black color returns in the hybrid. Even the foliage of some garden-plants may afford instances, as for instance, the purplish amaranth (_Amaranthus caudatus_). It has a green variety, but the hybrid between the two has the red foliage of the species. Special marks in leaves and in flowers follow the same rule. Some varieties of the opium poppy have large black patches at the basal end of the petals, while in others this pattern is entirely white. In crossing two such varieties, [283] for instance, the dark "Mephisto" with the white-hearted "Danebrog," the hybrid shows the active character of the dark pattern. Hairy species crossed with their smooth varieties produce hairy hybrids, as in some wheats, in the campion (_Lychnis_), in _Biscutella_ and others. The same holds good for the crosses between spiny species and their unarmed derivatives, as in the thorn-apple, the corn-crowfoot (_Ranunculus arvensis_) and others. Lack of starch in seeds is observed in some varieties of corn and of peas. When such derivatives are crossed with ordinary starch-producing types, the starch prevails in the hybrid. It would take too much time to give further examples. But there is still one point which should be insisted upon. It is not the systematic relation of the two parents of a cross, that is decisive, but only the occurrence of the same quality, in the one in an active, and in the other in an inactive condition. Hence, whenever this relation occurs between the parents of a cross, the active quality prevails in the hybrid, even when the parents differ from each other in other respects so as to be distinguished as systematic species. The white and red campions give a red hybrid, the black and pale henbane (_Hyoscyamus niger_ and _H. pallidus_) give a hybrid [284] with the purple veins and center in the corolla of the former, the white and blue thornapple produce a blue hybrid, and so on. Instances of this sort are common in cultivated plants. Having given this long list of examples of the rule of the dominancy of the active character over the opposite dormant unit, the question naturally arises as to how the antagonistic units are combined in the hybrid. This question is of paramount importance in the consideration of the offspring of the hybrids. But before taking it up it is as well to learn the real signification of recessiveness in the hybrids themselves. Recessive characters are shown by those rare cases, in which hybrids revert to the varietal parent in the vegetative way. In other words by bud-variations or sports, analogous to the splitting of Adam's laburnum into its parents, by means of bud-variation already described. But here the wide range of differentiating characters of the parents of this most curious hybrid fail. The illustrative examples are extremely simple, and are limited to the active and inactive condition of only one quality. An instance is given by the long-leaved veronica (_Veronica longifolia_), which has bluish flowers in long spikes. The hybrid between [285] this species and its white variety has a blue corolla. But occasionally it produces some purely white flowers, showing its power of separating the parental heritages, combined in its internal structures. This reversion is not common, but in thousands of flowering spikes one may expect to find at least one of them. Sometimes it is a whole stem springing from the underground system and bearing only white flowers on all its spikes. In other instances it is only a side branch which reverts and forms white flowers on a stem, the other spikes of which remain bluish. Sometimes a spike even differentiates longitudinally, bearing on one side blue and on the other white corollas, and the white stripe running over the spike may be seen to be long and large, or narrow and short in various degrees. In such cases it is evident that the heritages of the parents remain uninfluenced by each other during the whole life of the hybrid, working side by side, but the active element always prevails over its latent opponent which is ready to break free whenever an opportunity is offered. It is now generally assumed that this incomplete mixture of the parental qualities in a hybrid, this uncertain and limited combination is the true cause of the many deviations, exhibited by varietal hybrids when compared with their [286] parents. Partial departures are rare in the hybrids themselves, but in their offspring the divergence becomes the rule. Segregation seems to be a very difficult process in the vegetative way, but it must be very easy in sexual reproduction, indeed so easy as to show itself in nearly every single instance. Leaving this first generation, the original hybrids, we now come to a discussion of their offspring. Hybrids should be fertilized either by their own pollen, or by that of other individuals born from the same cross. Only in this case can the offspring be considered as a means of arriving at a decision as to the internal nature of the hybrids themselves. Breeders generally prefer to fertilize hybrids with the pollen of their parents. But this operation is to be considered as a new cross, and consequently is wholly excluded from our present discussion. Hence it follows that a clear insight into the heredity of hybrids may be expected only from scientific experiments. Furthermore some of the diversity observed as a result of ordinary crosses, may be due to the instability of the parents themselves or at least of one of them, since breeders ordinarily choose for their crosses some already very variable strain. Combining such a strain with the desirable qualities of some newly imported species, a new strain may [287] result, having the new attribute in addition to all the variability of the old types. In scientific experiments made for the purpose of investigating the general laws of hybridity, such complex cases are therefore to be wholly excluded. The hereditary purity of the parents must be considered as one of the first conditions of success. Moreover the progeny must be numerous, since neither constancy, nor the exact proportions in the case of instability, can be determined with a small lot of plants. Finally, and in order to come to a definite choice of research material, we should keep in mind that the chief object is to ascertain the relation of the offspring to their parents. Now in nearly all cases the seeds are separated from the fruits and from one another, before it becomes possible to judge of their qualities. One may open a fruit and count the seeds, but ordinarily nothing is noted as to their characters. In this respect no other plant equals the corn or maize, as the kernels remain together on the spike, and as it has more than one variety characterized by the color, or constitution, or other qualities of the grains. A corn-grain, however, is not a seed, but a fruit containing a seed. Hence the outer parts pertain to the parent plant and only the innermost ones to the [288] seedling and therefore to the following generation. Fruit-characters thus do not offer the qualities we need, only the qualities resulting from fertilizations are characteristic of the new generation. Such attributes are afforded in some cases by the color, in others by the chemical constitution. We will choose the latter, and take the sugarcorn in comparison with the ordinary or starch producing forms for our starting point. Both sugar- and starch-corns have smooth fruits when ripening. No difference is to be seen in the young ripe spikes. Only the taste, or a direct chemical analysis might reveal the dissimilarity. But as soon as the spikes are dried, a diversity is apparent. The starchy grains remain smooth, but the sugary kernels lose so much water that they become wrinkled. The former becomes opaque, the latter more or less transparent. Every single kernel may instantly be recognized as belonging to either of the types in question, even if but a single grain of the opposite quality might be met with on a spike. Kernels can be counted on the spike, and since ordinary spikes may bear from 300-500 grains and often more, the numerical relation of the different types may be deduced with great accuracy. Coming now to our experiment, both starchy [289] and sugary varieties are in this respect wholly constant, when cultivated separately. No change is to be seen in the spikes. Furthermore it is very easy to make the crosses. The best way is to cultivate both types in alternate rows and to cut off the staminate panicles a few days before they open their first flowers. If this operation is done on all the individuals of one variety, sparing all the panicles of the other, it is manifest that all the plants will become fertilized by the latter, and hence that the castrated plants will only bear hybrid seeds. The experiment may be made in two ways; by castrating the sugary or the starchy variety. In both cases the hybrid kernels are the same. As to their composition they repeat the active character of the starchy variety. The sugar is only accumulated as a result of an incapacity of changing it into starch, and the lack of this capacity is to be considered as a retrogressive varietal mark. The starch-producing unit character, which is active in the ordinary sorts of corns, is therefore latent in sugar-corn. In order to obtain the second generation, the hybrid grains are sown under ordinary conditions, but sufficiently distant from any other variety of corn to insure pure fertilization. The several individuals may be left to pollinate [290] each other, or they may be artificially pollinated with their own pollen. The outcome of the experiments is shown by the spikes, as soon as they dry. Each spike bears two sorts of kernels irregularly dispersed over its surface. In this point all the spikes are alike. On each of them one may see on the first inspection that the majority of the kernels are starch-containing seeds, while a minor part becomes wrinkled and transparent according to the rule for sugary seeds. This fact shows at once that the hybrid race is not stable, but has differentiated the parental characters, bringing those of the varietal parent to perfect purity and isolation. Whether the same holds good for the starchy parent, it is impossible to judge from the inspection of the spikes, since it has been seen in the first generation that the hybrid kernels are not visibly distinguished from those of the pure starch-producing grains. It is very easy to count the number of both sorts of grains in the spike of such a hybrid. In doing so we find, that the proportion is nearly the same on all the spikes, and only slight variations would be found in hundreds of them. One-fourth of the seeds are wrinkled and three-fourths are always smooth. The number may vary in single instances and be a little more or a little less than 25%, ranging, for [291] instance, from 20 to 27%, but as a rule, the average is found nearly equal to 25%. The sugary kernels, when separated from the hybrid spikes and sown separately, give rise to pure sugary race, in no degree inferior in purity to the original variety. But the starchy kernels are of different types, some of them being internally like the hybrids of the first generation and others like the original parent. To decide between these two possibilities, it is necessary to examine their progeny. For the study of this third hybrid generation we will now take another example, the opium poppies. They usually have a dark center in the flowers, the inferior parts of the four petals being stained a deep purple, or often nearly black. Many varieties exhibit this mark as a large black cross in the center of the flower. In other varieties the pigment is wanting, the cross being of a pure white. Obviously it is only reduced to a latent condition, as in so many other cases of loss of color, since it reappears in a hybrid with the parent-species. For my crosses I have taken the dark-centered "Mephisto" and the "Danebrog," or Danish flag, with a white cross on a red field. The second year the hybrids were all true to the type of "Mephisto." From the seeds of each artificially self-fertilized capsule, one-fourth (22.5%) [292] in each instance reverted to the varietal mark of the white cross, and three-fourths (77.5%) retained the dark heart. Once more the flowers were self-pollinated and the visits of insects excluded. The recessives now gave only recessives, and hence we may conclude that the varietal marks had returned to stability. The dark hearted or dominants behaved in two different ways. Some of them remained true to their type, all their offspring being dark-hearted. Evidently they had returned to the parent with the active mark, and had reassumed this type as purely as the recessives had reached theirs. But others kept true to the hybrid character of the former generation, repeating in their progeny exactly the same mixture as their parents, the hybrids of the first generation, had given. This third generation therefore gives evidence, that the second though apparently showing only two types, really consists of three different groups. Two of them have reassumed the stability of their original grandparents, and the third has retained the instability of the hybrid parents. The question now arises as to the numerical relation of these groups. Our experiments gave the following results: [293] Cross 1. Generation 2. Generation 3. Generation Mephisto 4- 100% Mephisto | / | / | 77.5 % Dom. | / \ > --All Mephisto \ | \ 9- all hybrids with 83-68% | 22.5 % Rec. dominants and 17-32% | recessives. 100% Danebrog. Danebrog Examining these figures we find one-fourth of constant recessives, as has already been said, further one-fourth of constant dominants, and the rest or one half as unstable hybrids. Both of the pure groups have therefore reappeared [293] in the same numbers. Calling A the specimens with the pure active mark, L those with the latent mark, and H the hybrids, these proportions may be expressed as follows: 1A+2H+1L. This simple law for the constitution of the second generation of varietal hybrids with a single differentiating mark in their parents is called the law of Mendel. Mendel published it in 1865, but his paper remained nearly unknown to scientific hybridists. It is only of late years that it has assumed a high place in scientific literature, and attained the first rank as an investigation on fundamental questions of heredity. [294] Read in the light of modern ideas on unit characters it is now one of the most important works on heredity and has already widespread and abiding influence on the philosophy of hybridism in general. But from its very nature and from the choice of the material made by Mendel, it is restricted to balanced or varietal crosses. It assumes pairs of characters and calls the active unit of the pair dominant, and the latent recessive, without further investigations of the question of latency. It was worked out by Mendel for a large group of varieties of peas, but it holds good, with only apparent exceptions, for a wide range of cases of crosses of varietal characters. Recently many instances have been tested, and even in many cases third and later generations have been counted, and whenever the evidence was complete enough to be trusted, Mendel's prophecy has been found to be right. According to this law of Mendel's the pairs of antagonistic characters in the hybrid split up in their progeny, some individuals reverting to the pure parental types, some crossing with each other anew, and so giving rise to a new generation of hybrids. Mendel has given a very suggestive and simple explanation of his formula. Putting this in the terminology of to-day, and limiting it to the occurrence of only [295] one differential unit in the parents, we may give it in the following manner. In fertilization, the characters of both parents are not uniformly mixed, but remain separated though most intimately combined in the hybrid throughout life. They are so combined as to work together nearly always, and to have nearly equal influence on all the processes of the whole individual evolution. But when the time arrives to produce progeny, or rather to produce the sexual cells through the combination of which the offspring arises, the two parental characters leave each other, and enter separately into the sexual cells. From this it may be seen that one-half of the pollen-cells will have the quality of one parent, and the other the quality of the other. And the same holds good for [296] the egg-cells. Obviously the qualities lie latent in the pollen and in the egg, but ready to be evolved after fertilization has taken place. Granting these premises, we may now ask as to the results of the fertilization of hybrids, when this is brought about by their own pollen. We assume that numerous pollen grains fertilize numerous egg cells. This assumption at once allows of applying the law of probability, and to infer that of each kind of pollen grains one-half will reach egg-cells with the same quality [297] and the other half ovules with the opposite character. Calling P pollen and O ovules, and representing the active mark by P and O, the latent qualities by P' and O', they would combine as follows: P + 0 giving uniform pairs with the active mark, P + 0' giving unequal pairs, P' + 0 giving unequal pairs, P' + 0' giving uniform pairs with the latent mark. In this combination the four groups are obviously of the same size, each containing one-fourth of the offspring. Manifestly they correspond exactly to the direct results of the experiments, P + O representing the individuals which reverted to the specific mark, P' + O' those who reassumed the varietal quality and P + O' and P + O' those who hybridized [298] for the second time. These considerations lead us to the following form of Mendel's, P + O = 1/4 Active or 1A, P + O' > = 1/2 Hybrid or 2 H, P' + O P' + O' = 1/4 Latent or 1 L, Which is evidently the same as Mendel's empirical law given above. To give the proof of these assumptions Mendel has devised a very simple crossing experiment, [299] which he has effected with his varieties of peas. I have repeated it with the sugar-corn, which gives far better material for demonstration. It starts from the inference that if dissimilarity among the pollen grains is excluded, the diversity of the ovules must at once became manifest and vice versa. In other terms, if a hybrid of the first generation is not allowed to fertilize itself, but is pollinated by one of its parents, the result will be in accordance with the Mendelian formula. In order to see an effect on the spikes produced in this way, it is of course necessary to fertilize them with the pollen of the variety, and not with that of the specific type. The latter would give partly pure starchy grains and partly hybrid kernels, but these would assume the same type. But if we pollinate the hybrid with pollen of a pure sugar-corn, we may predict the result as follows. If the spike of the hybrid contains dormant paternal marks in one-half of its flowers and in the other half maternal latent qualities, the sugar-corn pollen will combine with one-half of the ovules to give hybrids, and with the other half so as to give pure sugar-grains. Hence we see that it will be possible to count out directly the two groups of ovules on inspecting the ripe and dry spikes. Experience teaches us [298] that both are present, and in nearly equal numbers; one-half of the grains remaining smooth, and the other half becoming wrinkled. The corresponding experiment could be made with plants of a pure sugar-race by pollination with hybrid pollen. The spikes would show exactly the same mixture as in the above case, but now this may be considered as conclusive proof that half the pollen-grains represent the quality of one parent and the other half the quality of the other. Another corollary of Mendel's law is the following. In each generation two groups return to purity, and one-half remains hybrid. These last will repeat the same phenomenon of splitting in their progeny, and it is easily seen that the same rule will hold good for all succeeding generations. According to Mendel's principle, in each year there is a new hybridization, differing in no respect from the first and original one. If the hybrids only are propagated, each year will show one-fourth of the offspring returning to the specific character, one-fourth assuming the type of the variety and one-half remaining hybrid. I have tested this with a hybrid between the ordinary nightshade with black berries, and its variety, _Solanum nigrum chlorocarpum_, with pale yellow fruits. Eight generations of the hybrids were cultivated, [299] disregarding always the reverting offspring. At the end I counted the progeny of the sixth and seventh generations and found figures for their three groups of descendants, which exactly correspond to Mendel's formula. Until now we have limited ourselves to the consideration of single differentiating units. This discussion gives a clear insight into the fundamental phenomena of hybrid fertilization. It at once shows the correctness of the assumption of unit-characters, and of their pairing in the sexual combinations. But Mendel's law is not at all restricted to these simple cases. Quite on the contrary, it explains the most intricate questions of hybridization, providing they do not transgress the limits of symmetrical unions. But in this realm nearly all results may be calculated beforehand, on the ground of the principle of probability. Only one more assumption need be discussed. The several pairs of antagonistic characters must be independent from, and uninfluenced by, one another. This premise seems to hold good in the vast majority of cases, though rare exceptions seem to be not entirely wanting. Hence the necessity of taking all predictions from Mendel's law only as probabilities, which will prove true in most, but not necessarily in all cases. [300] But here we will limit ourselves to normal cases. The first example to be considered is obviously the assumption that the parents of a cross differ from each other in respect to two characters. A good illustrative example is afforded by the thorn-apple. I have crossed the blue flowered thorny form, usually known as _Datura Tatula_, with the white thornless type, designated as _D. Stramonium inermis_. Thorns and blue pigment are obviously active qualities, as they are dominant in the hybrids. In the second generation both pairs of characters are resolved into their constituents and paired anew according to Mendel's law. After isolating my hybrids during the period of flowering, I counted among their progeny: 128 individuals with blue flowers and thorns 47 individuals with blue flowers and without thorns 54 individuals with white flowers and thorns 21 individuals with white flowers and without thorns ---- 250 The significance of these numbers may easily be seen, when we calculate what was to be expected on the assumption that both characters follow Mendel's law, and that both are independent from each other. Then we would have three-fourths blue offspring and one-fourth individuals with white flowers. Each of these [301] two groups would consist of thorn-bearing and thornless plants, in the same numerical relation. Thus, we come to the four groups observed in our experiment, and are able to calculate their relative size in the following way: Proportion Blue with thorns 3/4 X 3/4 = 9/16 = 56.25% 9 Blue, unarmed 3/4 X 1/4 = 3/16 = 18.75% 3 White with thorns 1/4 X 3/4 = 3/16 = 18.75% 3 White, unarmed 1/4 X 1/4 = 1/16 = 6.25% 1 In order to compare this inference from Mendel's law and the assumption of independency, with the results of our experiments, we must calculate the figures of the latter in percentages. In this way we find: Found Calculated Blue with thorns 128=51% 56.25% Blue unarmed 47=19% 18.75% White with thorns 54=22% 18.75% White unarmed 21= 8% 6.25% The agreement of the experimental and the theoretical figures is as close as might be expected. This experiment is to be considered only as an illustrative example of a rule of wide application. The rule obviously will hold good in all such cases as comply with the two conditions already premised, viz.: that each character agrees with Mendel's law, and that both are wholly independent of each other. It is clear that our figures show the numerical composition [302] of the hybrid offspring for any single instance, irrespective of the morphological nature of the qualities involved. Mendel has proved the correctness of these deductions by his experiments with peas, and by combining their color (yellow or green) with the chemical composition (starch or sugar) and other pairs of characters. I will now give two further illustrations afforded by crosses of the ordinary campion. I used the red-flowered or day-campion, which is a perennial herb, and a smooth variety of the white evening-campion, which flowers as a rule in the first summer. The combination of flower-color and pubescence gave the following composition for the second hybrid generation: Number % Calculation Hairy and red 70 44 56.25% Hairy and white 23 14 18.75% Smooth and red 46 23 18.75% Smooth and white 19 12 6.25% For the combination of pubescence and the capacity of flowering in the first year I found: Number % Calculated Hairy, flowering 286 52 56.25% Hairy, without stem 128 23 18.75% Smooth, flowering 96 17 18.75% Smooth, without stem 42 8 6.25% Many other cases have been tested by different writers and the general result is the [303] applicability of Mendel's formula to all cases complying with the given conditions. Intentionally I have chosen for the last example two pairs of antagonisms, relating to the same pair of plants, and which may be tested in one experiment and combined in one calculation. For the latter we need only assume the same conditions as mentioned before, but now for three different qualities. It is easily seen that the third quality would split each of our four groups into two smaller ones in the proportion of 3/4 : 1/4. We would then get eight groups of the following composition: 9/16 X 3/4 = 27/64 or 42.2% 9/16 X 1/4 = 9/64 " 14.1% 3/16 X 3/4 = 9/64 " 14.1% 3/16 X 1/4 = 3/64 " 4.7% 3/16 X 3/4 = 9/64 " 14.1% 3/16 X 1/4 = 3/64 " 4.7% 1/16 X 3/4 = 3/64 " 4.7% 1/16 X 1/4 = 1/64 " 1.6% The characters chosen for our experiment include the absence of stem and flowers in the first year, and therefore would require a second year to determine the flower-color on the perennial specimens. Instead of doing so I have taken another character, shown by the teeth of the capsules when opening. These curve outwards [304] in the red campion, but lack this capacity in the evening-campion, diverging only until an upright position is reached. The combination of hairs, colors and teeth gives eight groups, and the counting of their respective numbers of individuals gave the following: Teeth Hairs Flowers of capsules Number % Calculated Hairy red curved 91 47 42.2% Hairy red straight 15 7.5 14.1% Hairy white curved 23 12 14.1% Hairy white straight 17 8.5 4.7% Smooth red curved 23 12 14.1% Smooth red straight 9 4.5 4.7% Smooth white curved 5 2.5 4.7% Smooth white straight 12 6 1.6% The agreement is as comprehensive as might be expected from an experiment with about 200 plants, and there can be no doubt that a repetition on a larger scale would give still closer agreement. In the same way we might proceed to crosses with four or more differentiating characters. But each new character will double the number of the groups. Four characters will combine into 16 groups, five into 32, six into 64, seven into 128, etc. Hence it is easily seen that the size of the experiments must be made larger and larger in the same ratio, if we intend to expect numbers equally trustworthy. For [305] seven differentiating marks 16,384 individuals are required for a complete series. And in this set the group with the seven attributes all in a latent condition would contain only a single individual. Unfortunately the practical value of these calculations is not very great. They indicate the size of the cultures required to get all the possible combinations, and show that in ordinary cases many thousands of individuals have to be cultivated, in order to exhaust the whole range of possibilities. They further show that among all these thousands, only very few are constant in all their characters; in fact, it may easily be seen that with seven differentiating points among the 16,384 named above, only one individual will have all the seven qualities in pure active, and only one will have them all in a purely dormant condition. Then there will be some with some attributes active and others latent, but their numbers will also be very small. All others will split up in the succeeding generation in regard to one or more of their apparently active marks. And since only in very rare cases the stable hybrids can be distinguished by external characters from the unstable ones, the stability of each individual bearing a desired combination of characters would have to be established by experiment [306] after pure fertilization. Mendel's law teaches us to predict the difficulties, but hardly shows any way to avoid them. It lays great stress on the old prescript of isolation and pure fertilization, but it will have to be worked out and applied to a large number of practical cases before it will gain a preeminent influence in horticultural practice. Or, as Bailey states it, we are only beginning to find a pathway through the bewildering maze of hybridization. This pathway is to be laid out with regard to the following considerations. We are not to cross species or varieties, or even accidental plants. We must cross unit-characters, and consider the plants only as the bearers of these units. We may assume that these units are represented in the hereditary substance of the cell-nucleus by definite bodies of too small a size to be seen, but constituting together the chromosomes. We may call these innermost representatives of the unit-characters pangenes, in accordance with Darwin's hypothesis of pangenesis, or give them any other name, or we may even wholly abstain from such theoretical discussion, and limit ourselves to the conception of the visible character-units. These units then may be present, or lacking and in the first case active, or latent. [307] True elementary species differ from each other in a number of unit-characters, which do not contrast. They have arisen by progressive mutation. One species has one kind of unit, another species has another kind. On combining these, there can be no interchange. Mendelism assumes such an interchange between units of the same character, but in a different condition. Activity and latency are such conditions, and therefore Mendel's law obviously applies to them. They require pairs of antagonistic qualities, and have no connection whatever with those qualities, which do not find an opponent in the other parent. Now, only pure varieties afford such pure conditions. When undergoing further modifications, some of them may be in the progressive line and others in the retrogressive. Progressive modifications give new units, which are not in contrast with any other, retrograde changes turn active units into the latent condition and so give rise to pairs. Ordinary species generally originate in this way, and hence differ from each other partly in specific, partly in varietal characters. As to the first, they give in their hybrids stable peculiarities, while as to the latter, they split up according to Mendel's law. Unpaired or unbalanced characters lie side by side with paired or balanced qualities, and they [308] do so in nearly all the crosses made for practical purposes, and in very many scientific experiments. Even Mendel's peas were not pure in this respect, much less do the campions noted above differ only in Mendelian characters. Comparative and systematic studies must be made to ascertain the true nature of every unit in every single plant, and crossing experiments must be based on these distinctions in order to decide what laws are applicable in any case. [309] D. EVER-SPORTING VARIETIES LECTURE XI STRIPED FLOWERS Terminology is an awkward thing. It is as disagreeable to be compelled to make new names, as to be constrained to use the old faulty ones. Different readers may associate different ideas with the same terms, and unfortunately this is the case with much of the terminology of the science of heredity and variability. What are species and what are varieties? How many different conceptions are conveyed by the terms constancy and variability? We are compelled to use them, but we are not at all sure that we are rightly understood when we do so. Gradually new terms arise and make their way. They have a more limited applicability than the old ones, and are more narrowly circumscribed. They are not to supplant the older terms, but permit their use in a more general way. [310] One of these doubtful terms is the word _sport_. It often means bud-variation, while in other cases it conveys the same idea as the old botanical term of mutation. But then all sorts of seemingly sudden variations are occasionally designated by the same term by one writer or another, and even accidental anomalies, such as teratological ascidia, are often said to arise by sports. If we compare all these different conceptions, we will find that their most general feature is the suddenness and the rarity of the phenomenon. They convey the idea of something unexpected, something not always or not regularly occurring. But even this demarcation is not universal, and there are processes that are regularly repeated and nevertheless are called sports. These at least should be designated by another name. In order to avoid confusion as far as possible, with the least change in existing terminology, I shall use the term "ever-sporting varieties" for such forms as are regularly propagated by seed, and of pure and not hybrid origin, but which sport in nearly every generation. The term is a new one, but the facts are for the most part new, and require to be considered in a new light. Its meaning will become clearer at once when the illustrations afforded by [311] striped flowers are introduced. In the following discussion it will be found most convenient to give a summary of what is known concerning them, and follow this by a consideration of the detailed evidence obtained experimentally, which supports the usage cited. The striped variety of the larkspur of our gardens is known to produce monochromatic flowers, in addition to striped ones. They may be borne by the same racemes, or on different branches, or some seedlings from the same parent-plant may bear monochromatic flowers while others may be striped. Such deviations are usually called sports. But they occur yearly and regularly and may be observed invariably when the cultures are large enough. Such a variety I shall call "ever-sporting." The striped larkspur is one of the oldest garden varieties. It has kept its capacity of sporting through centuries, and therefore may in some sense be said to be quite stable. Its changes are limited to a rather narrow circle, and this circle is as constant as the peculiarities of any other constant species or variety. But within this circle it is always changing from small stripes to broad streaks, and from them to pure colors. Here the variability is a thing of absolute constancy, while the constancy consists in eternal changes. Such apparent [312] contradictions are unavoidable, when we apply the old term to such unusual though not at all new cases. Combining the stability and the qualities of sports in one word, we may evidently best express it by the new term of eversporting variety. We will now discuss the exact nature of such varieties, and of the laws of heredity which govern them. But before doing so, I might point out, that this new type is a very common one. It embraces most of the so-called variable types in horticulture, and besides these a wide range of anomalies. Every ever-sporting variety has at least two different types, around and between which it varies in numerous grades, but to which it is absolutely limited. Variegated leaves fluctuate between green and white, or green and yellow, and display these colors in nearly all possible patterns. But there variability ends, and even the patterns are ordinarily narrowly prescribed in the single varieties. Double flowers afford a similar instance. On one side the single type, on the other the nearly wholly double model are the extreme limits, between which the variability is confined. So it is also with monstrosities. The race consists of anomalous and normal individuals, and displays between them all possible combinations of normal and monstrous [313] parts. But its variability is restricted to this group. And large as the group may seem on first inspection, it is in reality very narrow. Many monstrosities, such as fasciated branches, pitchers, split leaves, peloric flowers, and others constitute such ever-sporting varieties, repeating their anomalies year by year and generation after generation, changing as much as possible, but remaining absolutely true within their limits as long as the variety exists. It must be a very curious combination of the unit-characters which causes such a state of continuous variability. The pure quality of the species must be combined with the peculiarity of the variety in such a way, that the one excludes the other, or modifies it to some extent, although both never fully display themselves in the same part of the same plant. A corolla cannot be at once monochromatic and striped, nor can the same part of a stem be twisted and straight. But neighboring organs may show the opposite attributes side by side. In order to look closer into the real mechanism of this form of variability, and of this constant tendency to occasional reversions, it will be best to limit ourselves first to a single case, and to try to gather all the evidence, which can be obtained by an examination of the hereditary relations of its sundry constituents. [314] This may best be done by determining the degree of inheritance for the various constituents of the race during a series of years. It is only necessary to apply the two precautions of excluding all cross-fertilization, and of gathering the seeds of each individual separately. We do not need to ascertain whether the variety as such is permanent; this is already clear from the simple fact of its antiquity in so many cases. We wish to learn what part each individual, or each group of individuals with similar characters, play in the common line of inheritance. In other words, we must build up a genealogical tree, embracing several generations and a complete set of the single cases occurring within the variety, in order to allow of its being considered as a part of the genealogy of the whole. It should convey to us an idea of the hereditary relations during the life-time of the variety. It is manifest that the construction of such a genealogical tree requires a number of separate experiments. These should be extended over a series of years. Each should include a number of individuals large enough to allow the determination of the proportion of the different types among the offspring of a single plant. A species which is easily fertilized by its own pollen, and which bears capsules with [315] large quantities of seeds, obviously affords the best opportunities. As such, I have chosen the common snapdragon of the gardens, _Antirrhinum majus_. It has many striped varieties, some tall, others of middle height, or of dwarfed stature. In some the ground-color of the flowers is yellow, in others it is white, the yellow disappearing, with the exception of a large mark in the throat. On these ground-colors the red pigment is seen lying in streaks of pure carmine, with white intervals where the yellow fails, but combined with yellow to make a fiery red, and with yellow intervals when that color is present. This yellow color is quite constant and does not vary in any marked degree, notwithstanding the fact that it seems to make narrower and broader stripes, according to the parts of the corolla left free by the red pigment. But it is easily seen that this appearance is only a fallacious one. The variety of snapdragon chosen was of medium height and with the yellow ground-color, and is known by horticulturists as _A. majus luteum rubro-striatum_. As the yellow tinge showed itself to be invariable; I may limit my description to the red stripes. Some flowers of this race are striped, others are not. On a hasty survey there seem to be three types, pure yellow, pure red, and stripes [316] with all their intermediate links of narrower and broader, fewer and more numerous streaks. But on a close inspection one does not succeed in finding pure yellow racemes. Little lines of red may be found on nearly every flower. They are the extreme type on this side of the range of variability. From them an almost endless range of patterns passes over to the broadest stripes and even to whole sections of a pure red. But then, between these and the wholly red flowers we observe a gap, which may be narrower by the choice of numerous broad striped individuals, but which is never wholly filled up. Hence we see that the red flowers are a separate type within the striped variety. This red type springs yearly from the striped form, and yearly reverts to it. This is what in the usual descriptions of this snapdragon, is called its sporting. The breadth of the streaks is considered to be an ordinary case of variability, but the red flowers appear suddenly, without the expected links. Therefore they are to be considered as sports. Similarly the red forms may suddenly produce striped ones, and this too is to be taken as a sport, according to the usual conception of the word. Such sports may occur in different ways. Either by seeds, or by buds, or even within the single spikes. Both opposite reversions, [317] from striped to red and from red to stripes, occur by seed, even by the strictest exclusion of cross-fertilization. As far as my experiments go, they are the rule, and parent-plants that do not give such reversions, at least in some of their offspring, are very rare, if not wholly wanting. Bud-variations and variations within the spike I have as yet only observed on the striped individuals, and never on the red ones, though I am confident that they might appear in larger series of experiments. Both cases are more common on individuals with broad stripes than on plants bearing only the narrower red lines, as might be expected, but even on the almost purely yellow individuals they may be seen from time to time. Bud-variations produce branches with spikes of uniform red flowers. Every bud of the plant seems to have equal chances to be transformed in this way. Some striped racemes bear a few red flowers, which ordinarily are inserted on one side of the spike only. As they often cover a sharply defined section of the raceme, this circumstance has given rise to the term of sectional variability to cover such cases. Sometimes the section is demarcated on the axis of the flower-spike by a brownish or reddish color, sharply contrasting with the green hue of the remaining parts. Sectional variation may be looked at as a [318] special type of bud-variation, and from this point of view we may simplify our inquiry and limit ourselves to the inheritance of three types, the striped plants, the red plants and the red asexual variants of the striped individuals. In each case the heredity should be observed not only for one, but at least for two successive generations. Leaving these introductory remarks I now come at once to the genealogical tree, as it may be deduced from my experiments: Year 1896 95% Striped 84% Red | | 1895 Striped Individual Red Indiv. \ / 1895 98% Striped 71% Red | | 1894 Striped branches. Red branches. \ / 1894 98% Striped 76% Red | | 1893 90% Striped Indiv. 10% Red Indiv. \ / 1892 Striped Individual This experiment was begun in the year 1892 with one individual out of a large lot of striped plants grown from seeds which I had purchased from a firm in Erfurt. The capsules were gathered separately from this individual and about 40 flowering plants were obtained from the seeds in the following year. Most of them had neatly striped flowers, some displayed broader stripes and spare flowers were seen with one [319] half wholly red. Four individuals were found with only uniform red flowers. These were isolated and artificially pollinated, and the same was done with some of the best striped individuals. The seeds from every parent were sown separately, so as to allow the determination of the proportion of uniform red individuals in the progeny. Neither group was constant in its offspring. But as might be expected, the type of the parent plant prevailed in both groups, and more strongly so in the instances with the striped, than with the red ones. Or, in other words seed-reversions were more numerous among the already reverted reds than among the striped type itself. I counted 2% reversion in the latter case, but 24% from the red parents. Among the striped plants from the striped parents, I found some that produced bud variations. I succeeded in isolating these red flowering branches in paper bags and in pollinating them with their own pollen, and subjected the striped spikes of the same individuals to a similar treatment. Three individuals gave a sufficient harvest from both types, and these six lots of seeds were sown separately. The striped flowers repeated their character in 98% of their offspring, the red twigs in only 71%, the [320] remaining individuals sporting into the opposite group. In the following year I continued the experiment with the seeds of the offspring of the red bud-variations. The striped individuals gave 95%, but in the red ones only 84% of the progeny remained true to the parent type. From these figures it is manifest that the red and striped types differ from one another not only in their visible attributes, but also in the degree of their heredity. The striped individuals repeat their peculiarity in 90-98% of their progeny, 2-10% sporting into the uniform red color. On the other hand the red individuals are constant in 71-84% of their offspring, while 16-29% go over to the striped type. Or, briefly, both types are inherited to a high degree, but the striped type is more strictly inherited than the red one. Moreover the figures show that the degree of inheritance is not contingent upon the question as to how the sport may have arisen. Bud-sports show the same degree of inheritance as seed-sports. Sexual and asexual variability therefore seem to be one and the same process in this instance. But the deeper meaning of this and other special features of our genealogical tree are still awaiting further investigation. It seems that much important evidence might [321] come from an extension of this line of work. Perhaps it might even throw some light on the intimate nature of the bud-variations of ever-sporting varieties in general. Sectional variations remain to be tested as to the degree of inheritance exhibited, and the different occurrences as to the breadth of the streaks require similar treatment. In ordinary horticultural practice it is desirable to give some guarantee as to what may be expected to come from the seeds of brightly striped flowers. Neither the pure red type, nor the nearly yellow racemes are the object of the culture, as both of them may be had pure from their, own separate varieties. In order to insure proper striping, both extremes are usually rejected and should be rooted out as soon as the flowering period begins. Similarly the broad-striped ones should be rejected, as they give a too large amount of uniform red flowers. Clearly, but not broadly striped individuals always yield the most reliable seed. Summing up once more the results of our pedigree-experiment, we may assert that the striped variety of the snapdragon is wholly permanent, including the two opposite types of uniform color and of stripes. It must have been so since it first originated from the invariable uniform [322] varieties, about the middle of the last century, in the nursery of Messrs. Vilmorin, and probably it will remain so as long as popular taste supports its cultivation. It has never been observed to transgress its limits or to sport into varieties without reversions or sports. It fluctuates from one extreme to the other yearly, always recurring in the following year, or even in the same summer by single buds. Highly variable within its limits, it is absolutely constant or permanent, when considered as a definite group. Similar cases occur not rarely among cultivated plants. In the wild state they seem to be wholly wanting. Neither are they met with as occasional anomalies nor as distinct varieties. On the contrary, many garden-flowers that are colored in the species, and besides this have a white or yellow variety, have also striped sorts. The oldest instance is probably the marvel of Peru, _Mirabilis Jalappa_, which already had more than one striped variety at the time of its introduction from Peru into the European gardens, about the beginning of the seventeenth century. Stocks, liver-leaf (_Hepatica_), dame's violet (_Hesperis_), Sweet William (_Dianthus barbatus_), and periwinkles (_Vinca minor_) seem to be in the same condition, as their striped varieties were already quoted [323] by the writers of the same century. Tulips, hyacinths, _Cyclamen_, _Azalea_, _Camellia_, and even such types of garden-plants as the meadow crane's-bill (_Geranium pratensev) have striped varieties. It is always the red or blue color which occurs in stripes, the underlying ground being white or yellow, according to the presence or absence of the yellow in the original color mixture. All these varieties are known to be permanent, coming true during long series of successive generations. But very little is known concerning the more minute details of their hereditary qualities. They come from seed, when this is taken from striped individuals, and thence revert from time to time to the corresponding monochromatic type. But whether they would do so when self-fertilized, and whether the reversionary individuals are always bound to return towards the center of the group or towards the opposite limit, remains to be investigated. Presumably there is nowhere a real transgression of the limits, and never or only very rarely and at long intervals of time a true production of another race with other hereditary qualities. In order to satisfy myself on these points, I made some pedigree-cultures with the striped forms of dame's violet (_Hesperis matronalis_) [324] and of _Clarkia pulchella_. Both of them are ever-sporting varieties. The experiments were conducted during five generations with the violet, and during four with the striped Clarkia, including the progeny of the striped and of the monochromatic red offspring of a primitive striped plant. I need not give the figures here for the numerical relations between the different types of each group, and shall limit myself to the statement that they behaved in exactly the same manner as the snapdragon. It is worth while to dwell a moment on the capacity of the individuals with red flowers to reproduce the striped type among their offspring. For it is manifest that this latter quality must have lain dormant in them during their whole life. Darwin has already pointed out that when a character of a grandparent, which is wanting in the progeny, reappears in the second generation, this quality must always be assumed to have been present though latent in the intermediate generation. To the many instances given by him of such alternative inheritance, the monochromatic reversionists of the striped varieties are to be added as a new type. It is moreover, a very suggestive type, since the latency is manifestly of quite another character than for instance in the case of Mendelian hybrids, and probably more allied to those instances, [325] where secondary sexual marks, which are as a rule only evolved by one sex, are transferred to the offspring through the other. Stripes are by no means limited to flowers. They may affect the whole foliage, or the fruits and the seeds, and even the roots. But all such cases occur much more rarely than the striped flowers. An interesting instance of striped roots is afforded by radishes. White and red varieties of different shapes are cultivated. Besides them sometimes a curious motley sort may be seen in the markets, which is white with red spots, which are few and narrow in some samples, and more numerous and broader in others. But what is very peculiar and striking is the circumstance, that these stripes do not extend in a longitudinal, but in a transverse direction. Obviously this must be the effect of the very notable growth in thickness. Assuming that the colored regions were small in the beginning, they must have been drawn out during the process of thickening of the root, and changed into transverse lines. Rarely a streak may have had its greatest extension in a transverse direction from the beginning, in which case it would only be broadened and not definitely changed in its direction. This variety being a very fine one, and more agreeable to the eye than the uniform colors, is [326] being more largely cultivated in some countries. It has one great drawback: it never comes wholly true from seed. It may be grown in full isolation, and carefully selected, all red or nearly monochromatic samples being rooted out long before blooming, but nevertheless the seed will always produce some red roots. The most careful selection, pursued through a number of years, has not been sufficient to get rid of this regular occurrence of reversionary individuals. Seed-growers receive many complaints from their clients on this account, but they are not able to remove the difficulty. This experience is in full agreement with the experimental evidence given by the snapdragon, and it would certainly be very interesting to make a complete pedigree-culture with the radishes to test definitely their compliance with the rules observed for striped flowers. Horticulturists in such cases are in the habit of limiting themselves to the sale of so-called mixed seeds. From these no client expects purity, and the normal and hereditary diversity of types is here in some sense concealed under the impurities included in the mixture from lack of selection. Such cases invite scrutiny, and would, no doubt, with the methods of isolation, artificial pollination, and the sowing of the seeds separately from each parent, yield [327] results of great scientific value. Any one who has a garden, and sufficient perseverance to make pure cultures during a series of years might make important contributions to scientific knowledge in this way. Choice might be made from among a wide range of different types. A variety of corn called "Harlequin" shows stripes on its kernels, and one ear may offer nearly white and nearly red seeds and all the possible intermediate steps between them. From these seeds the next generation will repeat the motley ears, but some specimens will produce ears of uniform kernels of a dark purple, showing thus the ordinary way of reversion. Some varieties of beans have spotted seeds, and among a lot of them one may be sure to find some purely red ones. It remains to be investigated what will be their offspring, and whether they are due to partial or to individual variation. The cockscomb (_Celosia cristata_) has varieties of nearly all colors from white and yellow to red and orange, and besides them some striped varieties occur in our gardens, with the stripes going from the lower parts of the stem up to the very crest of the comb. They are on sale as constant varieties, but nothing has as yet been recorded concerning their peculiar behavior in the inheritance of the stripes. [328] Striped grapes, apples and other fruits might be mentioned in this connection. Before leaving the striped varieties, attention is called to an interesting deduction, which probably gives an explanation of one of the most widely known instances of ever-sporting garden plants. Striped races always include two types. Both of them are fertile, and each of them reproduces in its offspring both its own and the alternate type. It is like a game of ball, in which the opposing parties always return the ball. But now suppose that only one of the types were fertile and the other for some reason wholly sterile, and assume the reversionary, or primitive monochromatic individuals to be fertile, and the derivative striped specimens to bloom without seed. If this were the case, knowledge concerning the hereditary qualities would be greatly limited. In fact the whole pedigree would be reduced to a monochromatic strain, which would in each generation sport in some individuals into the striped variety. But, being sterile, they would not be able to propagate themselves. Such seems to be the case with the double flowered stocks. Their double flowers produce neither stamens nor pistils, and as each individual is either double or single in all its flowers, the doubles are wholly destitute of seed. [329] Nevertheless, they are only reproduced by seed from single flowers, being an annual or biennial species. Stocks are a large family, and include a wonderful variety of colors, ranging from white and yellow to purple and red, and with some variations toward blue. They exhibit also diversity in the habit of growth. Some are annuals, including the ten-week and pyramidal forms; others are intermediates and are suitable for pot-culture; and the biennial sorts include the well-known "Brompton" and "Queen" varieties. Some are large and others are small or dwarf. For their brightness, durability and fragrance, they are deservedly popular. There are even some striped varieties. Horticulturists and amateurs generally know that seed can be obtained from single stocks only, and that the double flowers never produce any. It is not difficult to choose single plants that will produce a large percentage of double blossoms in the following generation. But only a percentage, for the experiments of the most skilled growers have never enabled them to save seed, which would result entirely in double flowering plants. Each generation in its turn is a motley assembly of singles and doubles. Before looking closer into the hereditary peculiarities of this old and interesting ever-sporting [330] variety, it may be as well to give a short description of the plants with double flowers. Generally speaking there are two principal types of doubles. One is by the conversion of stamens into petals, and the other is an anomaly, known under the name of _petalomany_. The change of stamens into petals is a gradual modification. All intermediate steps are easily to be found. In some flowers all stamens may be enlarged, in others only part of them. Often the broadened filaments bear one or two fertile anthers. The fertility is no doubt diminished, but not wholly destroyed. Individual specimens may occur, which cannot produce any seed, but then others of the same lot may be as fertile as can be desired. As a whole, such double varieties are regularly propagated by seed. Petalomany is the tendency of the axis of some flowers never to make any stamens or pistils, not even in altered or rudimentary form. Instead of these, they simply continue producing petals, going on with this production without any other limit than the supply of available food. Numerous petals fill the entire space within the outer rays, and in the heart of the flower innumerable young ones are developed half-way, not obtaining food enough to attain [331] full size. Absolute sterility is the natural consequence of this state of things. Hence it is impossible to have races of petalomanous types. If the abnormality happens to show itself in a species, which normally propagates itself in an asexual way, the type may become a vegetative variety, and be multiplied by bulbs, buds or cuttings, etc. Some cultivated anemones and crowfoots (_Ranunculus_) are of this character, and even the marsh-marigold (_Caltha palustris_) has a petalomanous variety. I once found in a meadow such a form of the meadow-buttercup (_Ranunculus_ acris_), and succeeded in keeping it in my garden for several years, but it did not make seeds and finally died. Camellias are known to have both types of double flowers. The petalomanous type is highly regular in structure, so much so as to be too uniform in all its parts to be pleasing, while the conversion of stamens into petals in the alternative varieties gives to these flowers a more lively diversity of structure. Lilies have a variety called _Lilium candidum flore pleno_, in which the flowers seem to be converted into a long spike of bright, white narrow bracts, crowded on an axis which never seems to cease their production. It is manifestly impossible to decide how all such sterile double flowers have originated. [332] Perhaps each of them originally had a congruent single-flowered form, from which it was produced by seed in the same way as the double stocks now are yearly. If this assumption is right, the corresponding fertile line is now lost; it has perhaps died out, or been masked. But it is not absolutely impossible that such strains might one day be discovered for one or another of these now sterile varieties. Returning to the stocks we are led to the conception that some varieties are absolutely single, while others consist of both single-flowered and double-flowered individuals. The single varieties are in respect to this character true to the original wild type. They never give seed which results in doubles, providing all intercrossing is excluded. The other varieties are ever-sporting, in the sense of this term previously assumed, but with the restriction that the sports are exclusively one-sided, and never return, owing to their absolute sterility. The oldest double varieties of stocks have attained an age of a century and more. During all this time they have had a continuous pedigree of fertile and single-flowered individuals, throwing off in each generation a definite number of doubles. This ratio is not at all dependent on chance or accident, nor is it even variable to a remarkable degree. Quite on the contrary [333] it is always the same, or nearly the same, and it is to be considered as an inherent quality of the race. If left to themselves, the single individuals always produce singles and doubles in the same quantity; if cultivated after some special method, the proportion may be slightly changed, bringing the proportion of doubles up to 60% or even more. Ordinarily the single and double members of such a race are quite equal in the remainder of their attributes, especially in the color of their flowers. But this is not always the case. The colors of such a race may repeat for themselves the peculiarities of the ever-sporting characters. It often happens that one color is more or less strictly allied to the doubles, and another to the singles. This sometimes makes it difficult to keep the various colors true. There are certain sorts, which invariably exhibit a difference in color between the single and the double flowers. The sulphur-yellow varieties may be adduced as illustrative examples, because in them the single flowers always come white. Hence in saving seed, it is impossible so to select the plant, that an occasional white does not also appear among the double flowers, agreeing in this deviation with the general rule of the eversporting varieties. I commend all the above instances to those [334] who wish to make pedigree-cultures. The cooperation of many is needed to bring about any notable advancement, since the best way to secure isolation is to restrict one's self to the culture of one strain, so as to avoid the intermixture of others. So many facts remain doubtful and open to investigation, that almost any lot of purchased seed may become the starting point for interesting researches. Among these the sulphur-yellow varieties should be considered in the first place. In respect to the great questions of heredity, the stocks offer many points of interest. Some of these features I will now try to describe, in order to show what still remains to be done, and in what manner the stocks may clear the way for the study of the ever-sporting varieties. The first point, is the question, which seeds become double-flowered and which single-flowered plants? Beyond all doubt, the determination has taken place before the ripening of the seed. But though the color of the seed is often indicative of the color of the flowers, as in some red or purple varieties, and though in balsams and some other instances the most "highly doubled" flowers are to be obtained from the biggest and plumpest seeds, no such rule seems to exist respecting the double stocks. Now if one half of the seeds gives doubles, and [335] the other half singles, the question arises, where are the singles and the doubles to be found on the parent-plant? The answer is partly given by the following experiment. Starting from the general rule of the great influence of nutrition on variability, it may be assumed that those seeds will give most doubles, that are best fed. Now it is manifest that the stem and larger branches are, in a better condition than the smaller twigs, and that likewise the first fruits have better chances than the ones formed later. Even in the same pod the uppermost seeds will be in a comparatively disadvantageous position. This conception leads to an experiment which is the basis of a practical method much used in France in order to get a higher percentage of seeds of double-flowering plants. This method consists in cutting off, in the first place the upper parts of all the larger spikes, in the second place, the upper third part of each pod, and lastly all the small and weak twigs. In doing so the percentage is claimed to go up to 67-70%, and in some instances even higher. This operation is to be performed as soon as the required number of flowers have ceased blossoming. All the nutrient materials, destined for the seeds, are now forced to flow into these relatively few embryos, and it is clear that [336] they will be far better nourished than if no operation were made. In order to control this experiment some breeders have made the operation on the fruits when ripe, instead of on the young pods, and have saved the seeds from the upper parts separately. This seed, produced in abundance, was found to be very poor in double flowers, containing only some 20-30%. On the contrary the percentage of doubles in the seed of the lower parts was somewhat augmented, and the average of both would have given the normal proportion of 50%. Opposed to the French method is the German practice of cultivating stocks, as I have seen it used on a very large scale at Erfurt and at other places. The stocks are grown in pots on small scaffolds, and not put on or into the earth. The obvious aim of this practice is to keep the earth in the pots dry, and accordingly they are only scantily watered. In consequence they cannot develop as fully as they would have done when planted directly in the beds, and they produce only small racemes and no weak twigs, eliminating thereby without further operation the weaker seeds as by the French method. The effect is increased by planting from 6-10 separate plants in each pot. It would be very interesting to make comparative [337] trials of both methods, in order to discover the true relation between the practice and the results reached. Bath should also be compared with cultures on open plots, which are said to give only 50% of doubles. This last method of culture is practiced wherever it is desired to produce great quantities of seeds at a low cost. Such trials would no doubt give an insight into the relations of hereditary characters to the distribution of the food within the plant. A second point is the proportional increase of the double-flowering seeds with age. If seed is kept for two or three years, the greater part of the grains will gradually die, and among the remainder there is found on sowing, a higher percentage of double ones. Hence we may infer that the single-flowered seeds are shorter lived than the doubles, and this obviously points to a greater weakness of the first. It is quite evident that there is some common cause for these facts and for the above cited experience, that the first and best pods give more doubles. Much, however, remains to be investigated before a satisfactory answer can be made to these questions. A third point is the curious practice, called by the French "esimpler," and which consists in pulling out the singles when very young. It seems to be done at an age when the flower-buds [338] are not yet visible, or at least are not far enough developed to show the real distinctive marks. Children may be employed to choose and destroy the singles. There are some slight differences in the fullness and roundness of the buds and the pubescence of the young leaves. Moreover the buds of the doubles are said to be sweeter to the taste than those of the singles. But as yet I have not been able to ascertain, whether any scientific investigation of this process has ever been made, though according to some communications made to me by the late Mr. Cornu, the practice seems to be very general in the environs of Paris. In summer large fields may be seen, bearing exclusively double flowers, owing to the weeding out of the singles long before flowering. Bud-variation is the last point to be taken up. It seems to be very rare with stocks, but some instances have been recorded in literature. Darwin mentions a double stock with a branch bearing single flowers, and other cases are known to have occurred. But in no instance does the seed of such a bud-variant seem to have been saved. Occasionally other reversions also occur. From time to time specimens appear with more luxurious growth and with divergent instead of erect pods. They are called, in Erfurt, "generals" on account [339] of their stiff and erect appearance, and they are marked by more divergent horns crowning the pods. They are said to produce only a relatively small number of doubles from their seeds, and even this small number might be due to fertilization with pollen of their neighbors. I saw some of these reversionary types; when inspecting the nurseries of Erfurt, but as they are, as a rule, thrown out before ripening their seed, nothing is exactly known about their real hereditary qualities. Much remains to be cleared up, but it seems that one of the best means to find a way through the bewildering maze of the phenomena of inheritance, is to make groups of related forms and to draw conclusions from a comparison of the members of such groups. Such comparisons must obviously give rise to questions, which in their turn will directly lead to experimental investigation. [340] LECTURE XII FIVE-LEAVED CLOVER Every one knows the "four-leaved" clover. It is occasionally found on lawns, in pastures and by the roadsides. Specimens with five leaflets may be found now and then in the same place, or on the same plant, but these are rarer. I have often seen isolated plants with quaternate leaves, but only rarely have I observed individuals with more than one such leaf. The two cases are essentially dissimilar. They may appear to differ but little morphologically, but from the point of view of heredity they are quite different. Isolated quaternate leaves are of but little interest, while the occurrence of many on the same individual indicates a distinct variety. In making experiments upon this point it is necessary to transplant the divergent individuals to a garden in order to furnish them proper cultural conditions and to keep them under constant observation. When a plant bearing a quaternate leaf is thus transplanted however, it rarely repeats the [341] anomaly. But when plants with two or more quaternate leaves on the same individual are chosen it indicates that it belongs to a definite race, which under suitable conditions may prove to become very rich in the anomalies in question. Obviously it is not always easy to decide definitely whether a given individual belongs to such a race or not. Many trials may be necessary to secure the special race. I had the good fortune to find two plants of clover, bearing one quinate and several quaternate leaves, on an excursion in the neighborhood of Loosdrecht in Holland. After transplanting them into my garden, I cultivated them during three years and observed a slowly increasing number of anomalous leaves. This number in one summer amounted to 46 quaternate and 16 quinate leaves, and it was evident that I had secured an instance of the rare "five-leaved" race which I am about to describe. Before doing so it seems desirable to look somewhat closer into the morphological features of the problem. Pinnate and palmate leaves often vary in the number of their parts. This variability is generally of the nature of a common fluctuation, the deviations grouping themselves around an average type in the ordinary way. Ash leaves bear five pairs, and [342] the mountain-ash (_Sorbus Aucuparia_) has six pairs of leaflets in addition to the terminal one. But this number varies slightly, the weaker leaves having less, the stronger more pairs than the average. Such however, is not the case, with ternate leaves, which seem to be quite constant. Four leaflets occur so very rarely that one seems justified in regarding them rather as an anomaly than, as a fluctuation. And this is confirmed by the almost universal absence of two-bladed clover-leaves. Considering the deviation as an anomaly, we may look into its nature. Such an inquiry shows that the supernumerary leaflets owe their origin to a splitting of one or more of the normal ones. This splitting is not terminal, as is often the case with other species, and as it may be seen sometimes in the clover. It is for the most part lateral. One of the lateral nerves grows out becoming a median nerve of the new leaflet. Intermediate steps are not wanting, though rare, and they show a gradual separation of some lateral part of a leaflet, until this division reaches the base and divides the leaflet into two almost equal parts. If this splitting occurs in one leaflet we get the "four-leaved" Clover, if it occurs in two there will be five leaflets. And if, besides this, the terminal leaflet produces a derivative on one or both of its sides, [343] we obtain a crown of six or seven leaflets on one stalk. Such were often met with in the race I had under cultivation, but as a rule it did not exceed this limit. The same phenomenon of a lateral doubling of leaflets may of course be met with in other instances. The common laburnum has a variety which often produces quaternate and quinate leaves, and in strawberries I have also seen instances of this abnormality. It occurs also in pinnate leaves, and complete sets of all the intermediate links may often be found on the false or bastard-acacia (_Robinia Pseud_Acacia_). Opposed to this increase of the number of leaflets, and still more rare and more curious is the occurrence of "single-leaved" varieties among trees and herbs with pinnate or ternate leaves. Only very few instances have been described, and are cultivated in gardens. The ashes and the bastard-acacia may be quoted among trees, and the "one-leaved" strawberry among herbs. Here it seems that several leaflets have been combined into one, since this one is, as a rule, much larger than the terminal leaflet of an ordinary leaf of the same species. These monophyllous varieties are interesting also on account of their continuous but often incomplete reversion to the normal type. [344] Pinnate and palmate leaves are no doubt derivative types. They must have originated from the ordinary simple leaf. The monophylly may therefore be considered as a reversion to a more primitive state and the monophyllous varieties may be called atavistic. On the other hand we have seen that these atavistic varieties may revert to their nearest progenitors, and this leads to the curious conception of positive and negative atavism. For if the change of compound leaves into single ones is a retrograde or negative step, the conversion of single or ternate leaves into pinnate and palmate ones must evidently be considered in this case as positive atavism. This discussion seems to throw some light on the increase of leaflets in the clover. The pea family, or the group of papilionaceous plants, has pinnate leaves ordinarily, which, according to our premises, must be considered as a derivative type. In the clovers and their allies this type reverts halfway to the single form, producing only three leaflets on each stalk. If now the clover increases its number of leaflets, this may be considered as a reversion to its nearest progenitors, the papilionaceous plants with pinnate leaves. Hence a halfway returning and therefore positive atavism. And as I have already mentioned in a former lecture, pinnate [345] leaves are also sometimes produced by my new race of clover. Returning to the original plants of this race, it is evidently impossible to decide whether they were really the beginning of a new strain, and had originated themselves by some sudden change from the common type, or whether they belonged to an old variety, which had propagated itself perhaps during centuries, unobserved by man. But the same difficulty generally arises when new varieties are discovered. Even the behavior of the plants themselves or of their progeny does not afford any means of deciding the question. The simplest way of stating the matter therefore, is to say that I accidentally found two individuals of the "five-leaved" race. By transplanting them into my garden, I have isolated them and kept them free from cross-fertilization with the ordinary type. Moreover, I have brought them under such conditions as are necessary for the full development of their characters. And last but not least, I have tried to improve this character as far as possible by a very rigid and careful selection. The result of all this effort has been a rapid improvement of my strain. I saved the seed of the original plants in 1889 and cultivated the second generation in the following year. It [346] showed some increase of the anomaly, but not to a very remarkable degree. In the flowering period I selected four plants with the largest number of quaternate and quinate leaves and destroyed all the others. I counted in the average 25 anomalous organs on each of them. From their seed I raised the third generation of my culture in the year 1891. This generation included some 300 plants, on which above 8,000 leaves were counted. More than 1,000 were quaternate or quinate, the ternate leaves being still in the majority. But the experiment clearly showed that "four-leaved" clovers may be produced in any desired quantity, provided that the seed of the variety is available. In the summer only three, four and five leaflets on one stalk were seen, but towards the fall, and after the selection of the best individuals, this number increased and came up to six and seven in some rare instances. The selection in this year was by no means easy. Nearly all the individuals produced at least some quaternate leaves, and thereby showed the variety to be quite pure. I counted the abnormal organs on a large group of the best plants, and selected 20 excellent specimens from them, with more than one-third of all their leaves changed in the desired manner. Having brought my race up to this point, I [347] was able to introduce a new and far more easy mark, afforded by the seedlings, for my selections. This mark has since remained constant, and has brought about a rapid continuance of the improvement, without necessitating such large cultures. This seedling in the various species of clover usually begins with a first leaf above the cotyledons of a different structure from those that follow. It has only one blade instead of three. But in my variety the increase of the number of the leaflets may extend to these primary organs, and make them binate or even ternate. Now it is obvious that an individual, which begins with a divided primary leaf, will have a greater tendency to produce a large number of supernumerary leaflets than a plant which commences in the ordinary way. Or in other words, the primary leaves afford a sure criterion for the selection, and this selection may be made in the seed-pans. In consequence, no young individual with an undivided primary leaf was planted out. Choosing the 20 or 30 best specimens in the seed-pan, no further selection was required, and the whole lot could be left to cross-fertilization by insects. The observation of this distinguishing mark in the young seedlings has led to the discovery of another quality as a starting-paint for further [348] selection. According to the general rule of pedigree-culture, the seeds of each individual plant are always saved and sowed separately. This is done even with such species as the clover, which are infertile when self-pollinated, and which are incapable of artificial pollination on the required scale, since each flower produces only one seed. My clover was always left free to be pollinated by insects. Obviously this must have led to a diminution of the differentiating characters of the individual plants. But this does not go far enough to obliterate the differences, and the selection made among the seedlings will always throw out at least a large part of those that have suffered from the cross. Leaving this discussion, we may inquire closer into the nature of the new criterion afforded by the seedlings. Two methods present themselves. First, the choice of the best seedlings. In the second place it becomes possible to compare the parent-plants by counting the number of deviating seedlings. This leads to the establishment of a percentage for every single parent, and gives data for comparisons. Two or three hundreds of seeds from a parent may easily be grown in one pan, and in this way a sufficiently high degree of accuracy may be reached. Only those parents that give [349] the highest percentage are chosen, and among their progeny only the seedlings with trifoliolate primary leaves are planted out. The whole procedure of the selection is by this means confined to the glasshouse during the spring, and the beds need not be large, nor do they require any special care during the summer. By this method I brought my strain within two years up to an average of nearly 90% of the seedlings with a divided primary leaf. Around this average the real numbers fluctuated between the maximum of 99% and the minimum of 70% or thereabouts. This condition was reached by the sixth generation in the year 1894, and has since proved to be the limit, the group of figures remaining practically the same during all the succeeding generations. Such selected plants are very rich in leaves with four, five and six blades. Excluding the small leaves at the tops of the branches, and those on the numerous weaker side-branches, these three groups include the large majority of all the stronger leaves. In summer the range is wider, and besides many trifoliolate leaves the curiously shaped seven-bladed ones are not at all rare. In the fall and in the winter the range of variability is narrowed, and at first sight the plants often seem to bear only quinquefoliolate leaves. [350] I have cultivated a new generation of this race nearly every year since 1894, using always the strictest selection. This has led to a uniform type, but has not been adequate to produce any further improvement. Obviously the extreme limit, under the conditions of climate and soil, has been reached. This extreme type is always dependent upon repeated selection. No constant variety, in the older sense, has been obtained, nor was any indication afforded that such a type might ever be produced. On the contrary, it is manifest that the new form belongs to the group of ever-sporting varieties. It is never quite free from the old atavistic type of the trifoliolate leaves, and invariably, when external conditions become less favorable, this atavistic form is apt to gain dominion over the more refined varietal character. Reversions always occur, both partial and individual. Some instances of these reversions may now be given. They are not of such a striking character as those of the snapdragon. Intermediate steps are always occurring, both in the leaves themselves, and in the percentages of deviating seedlings of the several parent plants. On normal plants of my variety the quinquefoliolate leaves usually compose the majority, when there are no weak lateral branches, or when they are left out of consideration. Next [351] to these come the fours and the sixes, while the trifoliolate and seven-bladed types are nearly equal in number. But out of a lot of plants, grown from seed of the same parent, it is often possible to choose some in which one extreme prevails, and others with a preponderating number of leaves with the other extreme number of leaflets. If seed from these extremes are saved separately, one strain, that with numerous seven-bladed leaves will remain true to the type, but the other will diverge more or less, producing leaves with a varying number of subdivisions. Very few generations of such opposite selection are required to reduce the race to an utterly poor one. In three years I was able to nearly obliterate the type of my variety. I chose the seedlings with an undivided primary leaf, cultivated them and counted their offspring separately after the sowing. I found some parents with only 2-3% of seedlings with divided primary leaves. And by a repeated selection in this retrograde direction I succeeded in getting a great number of plants, which during the whole summer made only very few leaves with more than three blades. But an absolute reversion could no more be reached in this direction than in the normal one. Any sowing without selection would be [352] liable to reduce the strain to an average condition. The production of varietal and of atavistic leaves is dependent to a high degree on external conditions. It agrees with the general rule, that favorable circumstances strengthen the varietal peculiarities, while unfavorable conditions increase the number of the parts with the atavistic attribute. These influences may be seen to have their effect on the single individuals, as well as on the generations growing from their seed. I cannot cite here all the experimental material, but a single illustrative example may be given. I divided a strong individual into two parts, planted one in rich soil and the other in poor sand, and had both pollinated by bees with the pollen of some normal individuals of my variety growing between them. The seeds of both were saved and sown separately, and the two lots of offspring cultivated close to each other under the same external conditions. In the beginning no difference was seen, but as soon as the young plants had unfolded three or four leaves, the progeny of the better nourished half of the parent plant showed a manifest advance. This difference increased rapidly and was easily seen in the beds, even before the flowering period. This experience probably gives an explanation [353] why the quinquefoliolate variety is so seldom met with in the wild state. For even if it did occur more often, the plants would hardly find circumstances favorable enough for the full development of their varietal character. They must often be so poor in anomalous leaves as to be overlooked, or to be taken for instances of the commonly occurring quadrifoliolate leaves and therefore as not indicating the true variety. In the beginning of my discussion I have asserted the existence of two different races of "four-leaved" clovers, a poor one and a rich one, and have insisted on a sharp distinction between them. This distinction partly depends on experiments with clover, but in great part on tests with other plants. The previously mentioned circumstance, that clover cannot be pollinated on a sufficiently large scale otherwise than by insects, prevents trials in more than one direction at the same time and in the same garden. For this reason I have chosen another species of clover to be able to give proof or disproof of the assertion quoted. This species is the Italian, or crimson clover, which is sometimes also called scarlet clover (_Trifolium incarnatum_). It is commonly used in Europe as a crop on less fertile soils than are required by the red clover. It is annual [354] and erect and more or less hairy, and has stouter leaves than other kinds of clover. It has oblong or cylindrical heads with bright crimson flowers, and may be considered as one of the most showy types. As an annual it has some manifest advantages over the perennial species, especially in giving its harvest of hay at other seasons of the year. I found some stray quaternate leaves of this plant some years ago, and tried to win from them, through culture and selection, a race that would be as rich in these anomalies as the red clover. But the utmost care and the most rigid selection, and all the attention I could afford, failed to produce any result. It is now ten years since I commenced this experiment, and more than once I have been willing to give it up. Last year (1903) I cultivated some hundreds of selected plants, but though they yielded a few more instances of the desired anomaly than in the beginning, no trace of a truly rich race could be discovered. The experimental evidence of this failure shows at least that stray "four-leaves" may occur, which do not indicate the existence of a true "four-" or "five-leaved" variety. This conception seems destined to become of great value in the appreciation of anomalies, as they are usually found, either in the wild state [355] or in gardens. And before describing the details of my unsuccessful pedigree-culture, it may be as well to give some more instances of what occurs in nature. Stray anomalies are of course rare, but not so rare that they might not be found in large numbers when perseveringly sought for. Pitcher-like leaves may be found on many trees and shrubs and herbs, but ordinarily one or only two of them are seen in the course of many years on the same plant, or in the same strain. In some few instances they occur annually or nearly so, as in some individuals of the European lime-tree (_Tilia parvifolia_) and of the common magnolia (_Magnolia obovata_). Many of our older cultivated plants are very rich in anomalies of all kinds, and _Cyclamen_, _Fuchsia_, _Pelargonium_ and some others are notorious sources of teratologic phenomena. Deviations in flowers may often be seen, consisting of changes in the normal number of the several organs, or alterations in their shape and color. Leaves may have two tips, instead of one, the mid-vein being split near the apex, and the fissure extending more or less towards the base. Rays of the umbels of umbelliferous plants may grow together and become united in groups of two or more, and in the same way the fruits of [356] the composites may be united into groups. Many other instances could easily be given. If we select some of these anomalies for breeding-experiments, our results will not agree throughout, but will tend to group themselves under two heads. In some cases the isolation of the deviating individuals will at once show the existence of a distinct variety, which is capable of producing the anomaly in any desired number of instances; only dependent on a favorable treatment and a judicious selection. In other cases no treatment and no selection are adequate to give a similar result, and the anomaly remains refractory despite all our endeavors to breed it. The cockscomb and the peloric fox-glove are widely known instances of permanent anomalies, and others will be dealt with in future lectures. On the other hand I have often tried in vain to win an anomalous race from an accidental deviation, or to isolate a teratologic variety out of more common aberrations. Two illustrative examples may be quoted. In our next lecture we shall deal with a curious phenomenon in poppies, consisting in the change of the stamens into pistils and giving rise to a bright crown of secondary capsules around the central one. Similar anomalies may be occasionally met with in other species of the same genus. But they are rare, and may show [357] the conversion of only a single stamen in the described manner. I observed this anomaly in a poppy called _Papaver commutatum_, and subjected it during several years to a rigid selection of the richest individuals. No amelioration was to be gained and the culture had to be given up. In the same way I found on the bulbous buttercup (_Ranunculus bulbosus_) a strain varying largely in the number of the petals, amounting often to 6-8, and in some flowers even yet to higher figures. During five succeeding years I cultivated five generations, often in large numbers, selecting always those which had the highest number of petals, throwing out the remainder and saving the seed only from the very best plants. I got a strain of selected plants with an average number of nine petals in every flower, and found among 4,000 flowers four having 20 petals or more, coming up even to 31 in one instance. But such rare instances had no influence whatever on the selection, since they were not indicative of individual qualities, but occurred quite accidentally on flowers of plants having only the average number of petals. Now double flowers are widely known to occur in other species of the buttercups, both in the cultivated varieties and in some wild forms. For this reason it might be expected that through a continuous selection of [358] the individuals with the largest numbers a tendency to become double would be evolved. Such, however, was not the case. No propensity to vary in any definite direction could be observed. Quite on the contrary, an average condition was quickly reached, and then remained constant, strongly counteracting all selection. Such experiences clearly show that the same anomaly may occur in different species, and no doubt in strains of the same species from different localities, according to at least two different standards. The one is to be called the poor, and the other the rich variety. The first always produces relatively few instances of the deviation, the last is apt to give as many of them as desired. The first is only half-way a variety, and therefore would deserve the name of a half-race; the second is not yet a full constant variety, but always fluctuates to and fro between the varietal and the specific mark, ever-sporting in both directions. It holds a middle position between a half-race and a variety, and therefore might be called a "middle-race." But the term ever-sporting variety seems more adequate to convey a right idea of the nature of this curious type of inheritance. From this discussion it will be seen that the behavior of the crimson clover is not to be considered [359] as an exception, but as a widely occurring type of phenomenon, occurring perhaps in all sorts of teratologic deviations, and in wide ranges of species and genera. Hence it may be considered worth while to give some more details of this extended experiment. Ten years ago (1894-5) I bought and sowed about a pound of seed of the crimson clover. Among many thousands of normal seedlings I found two with three and one with four cotyledons. Trusting to the empirical rules of correlation, I transplanted these three individuals in order to isolate them in the flowering period. One of them produced during the ensuing summer one four-bladed and one five-bladed leaf. The seeds were saved separately and sown the following spring and the expected result could soon be seen. Among some 250 individual plants I counted 22 with one or two deviations, and 10 with from three to nine four- or five-bladed leaves. Proportions nearly similar have been observed repeatedly. Better nourished individuals have produced more deviating leaves on one plant, partly owing to the larger number of stems and branches, and poor or average specimens have mostly been without any aberration or with only one or two abnormal leaves. No further improvement could be attained. Quadrifoliolate leaves were always rare, never [360] attaining a number that would put its stamp on a whole bed. I have endeavored to get some six- and seven-bladed crimson clover leaves, but in vain; selection, culture of many hundreds of individuals, manure, and the best possible treatment has not been adequate to produce them. Of course I am quite convinced that a repetition of my experiment on a far larger scale would yield the desired types, but then only in such rare instances that they would have no influence whatever on the average, or on the improvement of the race. The eighth generation in the year 1903 has not been noticeably better than the second and third generations after the first selection. In comparing this statement with the results gained in the experiment with the red clover, the difference is at once striking. In one case a rich variety was isolated, and, by better treatment and sharp methods of selection, was brought up in a few years to its highest pitch of development. In the other case a very weak race was shown to exist, and no amount of work and perseverance was adequate to improve it to any noticeable degree. I wish to point out that the decision of what is to be expected from deviating specimens may become manifest within one or two generations. Even the generation grown from the seeds of [361] the first observed aberrant-individuals, if gathered after sufficient isolation during the period of blossoming, may show which type of inheritance is present, whether it is an unpromising half-race, or a richly endowed sporting variety. I have kept such strains repeatedly after the first isolation, and a special case, that of cotyledoneous aberrations, will be dealt with later. The first generation always gave a final decision, provided that a suitable method of cultivation for the species under observation was found at the beginning. This however, is a condition, which it is not at all easy to comply with, when new sorts are introduced into a garden. Especially so when they had been collected in the wild state. Often one or two years, sometimes more, are necessary to find the proper method of sowing, manuring, transplanting and, other cultural methods satisfactory to the plants. Many wild species require more care and more manure in gardens than the finest garden flowers. And a large number are known to be dependent on very particular conditions of soil. One of the most curious features of anomalies, which has been learned from accumulated instances, is the fact that they obey definite laws as to their occurrence on the different parts of the plant. Obviously such laws are [362] not apparent as long as each plant produces only one or two, or, at most, a few instances of the same deviation. On the contrary, any existing regularity must betray itself, as soon as a larger number of instances is produced. A rule of periodicity becomes most clearly manifest in such cases. This rule is shown by no other race in a more undoubted and evident manner than by the "five-leaved" clover. Evidently the several degrees of deviation, going from three to seven leaflets, may be regarded as responses to different degrees of variation, and their distribution over the stems and branches, or over the whole plant, may be considered as the manifestation of the ever-changing internal tendency to vary. Considered from this point of view, my plants always showed a definite periodicity in this distribution, which is the same for the whole plant. Each of them, and each of the larger branches, begin with atavistic leaves or with slight deviations. These are succeeded by greater deviations, but only the strongest axes show as many as seven leaflets on a stalk. This ordinarily does not occur before the height of development is reached, and often only towards its close. Then the deviation diminishes rapidly, returning often to atavistic leaves at the summit of the stem or branch. I give the numbers of the [363] leaves of a branch, in their order from the base to the top. They were as follows: 3. 4. 5. 6. 7. 5. 5. 4. But this is a selected case, and such regular examples of the expected periodicity are rarely found. Often one or more of the various steps are lacking, or even leaves with smaller numbers may be interspersed among those with larger numbers of leaflets. But while the regularity of the periodicity is in some degree diminished by such occurrences, yet the rule always holds good, when taken broadly. It may be expressed by stating that the bases and apices have on the average fewer leaflets on each leaf than the middle parts of the stem and branches, and that the number of leaflets gradually increases from the base toward a maximum, which is reached in organs on the middle or upper part of the axis, and then diminishes from this toward the apex. This periodicity is not limited to the stems and branches, considered singly, but also holds good in a comparison made between the branches of a single stem, in regard to their relative places on that stem. So it is also for the whole plant. The first stems, produced by the subterranean axis, ordinarily show only a low maximum deviation: the next succeeding being [364] more divergent and the last ones returning to less differentiated forms. It is evident that on a given stem the group of deviating leaves will be extended upward and downward, with the increase of the number of these organs. This shows that a stem, or even a plant, promises a higher degree of differentiation if it commences with its aberration earlier. Hence it becomes possible to discern the most promising individuals in early youth, and this conclusion leads to a very easy and reliable method of selection, which may be expressed simply as follows: the seedlings which commence earliest with the production of four- and five-foliolate leaves are the best and should be selected for the continuance of the race. And it is easily seen that this rule agrees with that given above, and which was followed in my pedigree-culture. Furthermore it is seen that there is a complete agreement between the law of periodicity and the responses of the deviations to nourishment and other conditions of life. Weak plants only produce low degrees of deviation, the stronger the individual becomes, the higher it reaches in the scale of differentiation, and the more often it develops leaves with five or more blades. Whether weakness or strength are derived from outer causes, or from the internal [365] succession of the periods of life, is evidently of no consequence, and in this way the law of periodicity may be regarded as a special instance of the more general law of response to external conditions. The validity of this law of periodicity is of course not limited to our "five-leaved" clover. Quite on the contrary it is universal in eversporting varieties. Moreover it may be ascertained and studied in connection with the most widely different morphologic abnormalities, and therefore affords easily accessible material for statistical inquiry. I will now give some further instances, but wish to insist first upon the necessity of an inquiry on a far larger scale, as the evidence as yet is very scanty. The great celandine (_Chelidonium majus_) has a very curious double variety. Its flowers are simpler and much more variable than in ordinary garden-varieties. The process of doubling consists mainly in a change of stamens into petals. This change is dependent on the season. On each stem the earliest flowers are single. These are succeeded by blossoms with one or two converted stamens, and towards the summer this number increases gradually, attaining 10-11 and in some instances even more altered filaments. Each year the same succession may be seen repeating itself on the stems of [366] the old roots. Double tuberous begonias are ordinarily absolutely sterile throughout the summer, but towards autumn the new flowers become less and less altered, producing some normal stamens and pistils among the majority of metamorphosed organs. From these flowers the seeds are saved. Sometimes similar flowers occur at the beginning of the flowering-period. Double garden-camomiles (_Chrysanthemum inodorum plenissimum_) and many other double varieties of garden-plants among the great family of the composites are very sensitive to external agencies, and their flower-heads are fuller the more favorable the external conditions. Towards the autumn many of them produce fewer and fewer converted heads and often only these are fertile and yield seeds. Ascidia afford another instance of this periodicity, though ordinarily they are by far too rare to show any regularity in their distribution. However, it is easy to observe that on lime-trees they prefer the lower parts of each twig, while on magnolias the terminal leaves of the branches are often pitcher-bearing. Ascidia of the white clover have been found in numbers, in my own experiment-garden, but always in the springtime. The thickleaved saxifrage (_Saxifraga crassifolia_) is often very productive of ascidia, especially in [367] the latter part of the season, and as these organs may be developed to very different degrees, they afford fine material for the study of the law of periodicity. On a garden-cytisus (_Cytisus candicans attleyanus_) I once had the good fortune to observe a branch with ascidia, which ordinarily are very rare in this species. It had produced seven ascidia in all, each formed by the conversion of one leaflet on the trifoliolate leaves. The first six leaves were destitute of this malformation and were quite normal. Then followed a group of five leaves, constituting the maximum of the period. The first bore one small pitcher-like blade, the second and third, each one highly modified organ, the fourth, two ascidia, and the last, one leaflet with slightly connate margins. The whole upper part of the branch was normal, with the exception of the seventeenth leaf, which showed a slight change in the same direction. All in all, the tendency to produce ascidia increased from the beginning to the tenth leaf, and decreased from this upward. The European Venus' looking-glass was observed in my garden to produce some quaternate and some quinate flowers on the same specimens. The quinate were placed at the end of the branches, those with four petals and sepals lower down. The peloric fox-glove shows the [368] highest degree of metamorphy in the terminal flowers of the stem itself, the weaker branches having but little tendency towards the formation of the anomaly. The European pine or _Pinus sylvestris_ ordinarily has two needles in each sheath, but trifoliolate sheaths occur on the stems and stronger branches, where they prefer, as a rule, the upper parts of the single annual shoots. _Camellia japonica_ is often striped in the fall and during the winter, but when flowering in the spring it returns to the monochromatic type. Peloric flowers are terminal in some cases, but occur in the lower parts of the flower-spikes in others. Some varieties of gladiolus commence on each spike with more or less double flowers, which, higher up, are replaced by single ones. A wide range of bulbs and perennial garden-plants develop their varietal characters only partly when grown from seed and flowering for the first time. The annual garden-forget-me-not of the Azores (_Myosotis azorica_) has a variety with curiously enlarged flowers, often producing 20 or more corolla-segments in one flower. But this number gradually diminishes as the season advances. It would be quite superfluous to give further proof of the general validity of the law of periodicity in ever-sporting varieties. [369] LECTURE XIII PISTILLODY IN POPPIES One of the most curious anomalies that may be met with in ornamental garden-plants is the conversion of stamens into pistils. It is neither common nor rare, but in most cases the change is so slight comparatively that it is ordinarily overlooked. In the opium-poppy, on the contrary, it is very showy, and heightens the ornamental effect of the young fruits after the fading of the flowers. Here the central capsule is surrounded by a large crown of metamorphosed stamens. This peculiarity has attracted the attention both of horticulturists and of botanists. As a rule not all the stamens are changed in this way but only those of the innermost rows. The outer stamens remain normal and fertile, and the flowers, when pollinated with their own pollen, bear as rich a harvest of seeds as other opium-poppies. The change affects both the filament and the anther, the former of which is dilated into a sheath. Within this sheath perfect [370] and more or less numerous ovules may be produced. The anthers become rudimentary and in their place broad leafy flaps are developed, which protrude laterally from the tip and constitute the stigmas. Ordinarily these altered organs are sterile, but in some instances a very small quantity of seed is produced, and when testing their viability I succeeded in raising a few plants from them. The same anomaly occurs in other plants. The common wall-flower (_Cheiranthus Cheiri_) and the houseleek (_Sempervivum tectorum_) are the best known instances. Both have repeatedly been described by various investigators. In compiling the literature of this subject it is very interesting to observe the two contrasting views respecting the nature of this anomaly. Some writers, and among them Masters in his "Vegetable Teratology" consider the deviations to be merely accidental. According to them some species are more subject to this anomaly than others, and the houseleek is said to be very prone to this change. Goeppert, Hofmeister and others occasionally found the pistilloid poppies in fields or gardens, and sowed their seeds in order to ascertain whether the accidental peculiarity was inheritable or not. On the other hand De Candolle in his "Prodromus" mentions the pistilloid wall-flowers as a distinct [371] variety, under the name of _Cheiranthus Cheiri gynantherus_, and the analogous form of the opium-poppy is not at all an accidental anomaly, but an old true horticultural variety, which can be bought everywhere under the names of _Papaver somniferum monstruosum_ or _polycephalum_. Since it is an annual plant, only the seeds are for sale, and this at once gives a sufficient proof of its heredity. In all cases, where it was met with accidentally by botanists, it is to be assumed that stray seeds had been casually mixed with those of other varieties, or that the habit had been transmitted by a spontaneous cross. Wherever opportunity led to experiments on heredity, distinct races were found to be in possession of this quality, while others were not. It is of no use to cultivate large numbers of wall-flowers in the hope of one day seeing the anomaly arise; the only means is to secure the strain from those who have got it. With poppies the various varieties are so often intercrossed by bees, that the appearance of an accidental change may sometimes be produced, and in the houseleek the pistilloid warily seems to be the ordinary one, the normal strain being very rare or perhaps wholly wanting. Our three illustrative examples are good and permanent races, producing their peculiar qualities [372] regularly and abundantly. In this respect they are however very variable and dependent on external circumstances. Such a regularity is not met with in other instances. Often pedigree-experiments lead to poor races, betraying their tendency to deviate only from time to time and in rare cases. Such instances constitute what we have called in a former lecture, "half races," and their occurrence indicates that the casual observation of an anomaly is not in itself adequate to give an opinion as to the chance of repetition in sowing experiments. A large number of species seem to belong to this case, and their names may be found in the above mentioned work by Masters and elsewhere. But no effort has yet been made to separate thoroughly the pistilloid half-races from the corresponding ever-sporting varieties. Some plants are recorded as being more liable to this peculiarity than others. Stamens are sometimes replaced by open carpels with naked ovules arising from their edges and even from their whole inner surfaces. This may be seen in distinct strains of the cultivated bulbous Begonia, and more rarely in primroses. Here the apex of the carpellary leaf is sometimes drawn out into a long style, terminated by a flattened spatulate stigma. The pistillody of the stamens is frequently [373] combined with another deviation in the poppies. This is the growing together of some of the altered stamens so as to constitute smaller or larger connate groups. Often two are united, sometimes three, four or more. Flowers with numerous altered stamens are seldom wholly free from this most undesirable secondary anomaly. I call it undesirable with respect to experiments on the variability of the character. For it may easily be seen that while it is feasible to count the stamens even when converted into pistils, it is not possible when groups of them are more or less intimately united into single bodies. This combination makes all enumeration difficult and inaccurate and often wholly unreliable. In such cases the observation is limited to a computation of the degree of the change, rather than to a strict numerical inquiry. Happily the responses to the experimental influences are so marked and distinct that even this method of describing them has proved to be wholly sufficient. In extreme instances I have seen all the changed stamens of a flower of the opium-poppy united into a single body, so as to form a close sheath all around the central ovary. Lesser sheaths, surrounding one-half or one-third of the capsule are of course less rarely met with. Leaving this description of the outer appearance [374] of our anomaly, we may now consider it from the double point of view of inheritance and variability. The fact of inheritance is shown by the experience of many authors, and by the circumstance already quoted, that the variety has been propagated from seed for more than half a century, and may be obtained from various seed merchants. In respect to the variability, the variety belongs to the ever-sporting group, constituting a type which is more closely related to the "five-leaved" clover than to the striped flowers or even the double stocks. It fluctuates around an average type with half filled crowns, going as far as possible in both directions, but never transgressing either limit. It is even doubtful whether the presumable limits are, under ordinary circumstances, ever reached. Obviously one extreme would be the conversion of all the stamens, and the other the absolute deficiency of any marked tendency to such a change. Both may occur, and will probably be met with from time to time. But they must be extremely rare, since in my own extensive experiments, which were strictly controlled, I never was able to find a single instance of either of them. Some of the outer stamens have always remained unchanged, yielding enough pollen for the artificial pollination of [375] the central ovary, and on the other hand some rudiments of hardened filaments were always left, even if they were reduced to small protuberances on the thalamus of the flower. Between these extremes all grades occur. From single, partially or wholly changed stamens upwards to 150 and over, all steps may be seen. It is a true fluctuating variability. There is an average of between 50 and 100, constituting a nearly filled crown around the central capsule. Around this average the smaller deviations are most numerous and the larger ones more rare. The inspection of any bed of the variety suffices to show that, taken broadly, the ordinary laws of fluctuating variability are applicable. No counting of the single individuals is required to dispel all doubts on this point. Moreover all intermediate steps respecting the conversion of the single stamens may nearly always be seen. Rarely all are changed into normal secondary ovaries with a stigma and with a cavity filled with ovules. Often the stigma is incomplete or even almost wanting, in other instances the ovules are lacking or the cavity itself is only partially developed. Not rarely some stamens are reduced and converted into thin hard stalks, without any appearance of an ovary at their tip. But then the demarcation [376] between them and the thalamus fails, so that they cannot be thrown off when the flower fades away, but remain as small stumps around the base of the more fully converted filaments. This fact would frequently render the enumeration of the altered organs quite unreliable. For these reasons I have chosen a group of arbitrary stages in order to express the degree of deviation for a given lot of plants. The limits were chosen so as to be sufficiently trustworthy and easy to ascertain. In each group the members could be counted, and a series of figures was reached by this means which allowed of a further comparison of the competing sets of plants. It should be stated that in such experiments and especially in the case of such a showy criterion as the pistilloid heads afford after the time of flowering is over, the inspection of the controlling beds at once indicates the result of the experiment. Even a hasty survey is in most cases sufficient to get a definite conclusion. Where this is not the case, the counting of the individuals of the various groups often does not add to the evidence, and the result remains uncertain. On the other hand, the impression made by the groups of plants on the experimenter and on his casual visitors, cannot well be conveyed to the readers of his account by [377] other means than by figures. For this reason the result of the experiments is expressed in this way. I made six groups. The first includes the cases where the whole circle is reduced to small rudiments. The second shows 1-10 secondary capsules. The two following constitute half a crown around the central fruit, the third going up to this limit, the fourth going from this limit to a nearly filled circle. Wholly filled circles of secondary capsules without gaps give the two last degrees, the fifth requiring only continuity of the circle, the sixth displaying a large and bright crown all around the central head. The fifth group ordinarily includes from 90-100 altered stamens, while the sixth has from 100-150 of these deviating parts. In ordinary cultures the third and fourth group, with their interrupted crowns, predominate. Large crowns are rare and flowers which at first sight seem to be wholly normal, occur only under circumstances definitely known to be unfavorable to growth, and to the development of the anomaly. Having reached by this means a very simple and easy method of stating the facts shown by equal lots under contrasting influences, we will now make use of it to inquire into the relation [378] of this exceptionally high degree of variability to the inner and outer conditions of life. As a rule, all experiments show the existence of such a relation. Unfavorable conditions reduce the numbers of altered stamens, favorable circumstances raise it to its highest point. This holds true for lots including hundreds of specimens, but also for the sundry heads of one bed, and often for one single plant. We may compare the terminal flower with those of the lateral branches on a plant, and when no special influences disturb the experiment, the terminal head ordinarily bears the richest crown. If the first has more than 100 metamorphosed parts, the latter have often less than 50 on the same plant. In poor soil, terminal heads are often reduced to 10-20 monstrous organs, and in such cases I found the lateral flowers of the same plants ordinarily with less than 10 altered stamens. In some cases I allowed the branches of the third and fourth degree, in other words, the side twigs of the first branches of my selected plants to grow out and produce flowers in the fall. They were ordinarily weak, sometimes very small, having only 5-9 stigmas on their central fruit. Secondary capsules were not seen on such flowers, even when the experiment was repeated on a [379] somewhat larger scale and during a series of years. Among the same lot of plants individual differences almost always occur. They are partly due to inequalities already existing in the seeds, and partly to the diversity of the various parts of the same bed. Some of the plants become stout and have large terminal heads. Others remain very weak, with a slender stem, small leaves and undersized flowers. The height and thickness of the stem, the growth of the foliage and of the axillary buds are the most obvious measures of the individual strength of the plant. The development of the terminal flower and the size of its ovary manifestly depends largely on this individual strength, as may be seen at once by the inspection of any bed of opium-poppies. Now this size of the head can easily be measured, either by its height or circumference, or by its weight. Moreover we can arrange them into a series according to their size. If we do this with the polycephalous variety, the relation between individual strength and degree of metamorphosis at once becomes manifest. The largest heads have the brightest crowns, and the number of supernumerary carpels diminishes in nearly exact proportion to the size of the fruits. Fruits with less than 50 altered stamens weighed on an average 5 grams, [380] those with 50-100 such organs 7 grams and those with a bright crown 10 grams, the appendices being removed before the weighing. Corresponding results have been reached by the comparison of the height of the capsules with their abnormal surroundings. The degree of development of the monstrosity is shown by this observation to be directly dependent on, and in a sense proportionate to the individual strength of the plant. The differences between the specimens grown from a single lot of seeds, for instance from the seeds of one self-fertilized capsule are, as I have said, partly due to the divergences which are always present in a bed, even if the utmost care has been taken to make it as uniform as possible. These local differences are ordinarily underrated and overlooked, and it is often considered to be sufficient to cultivate small lots of plants under apparently similar conditions on neighboring beds, to be justified in imputing all the observed deviations of the plants to hereditary inequalities. This of course is true for large lots, whenever the averages only are compared. In smaller experiments the external conditions of the single individuals should always be considered carefully. Lots of one or two square meters suffice for such comparisons, but smaller lots are always subject to chances and [381] possibilities, which should never be left out of consideration. Therefore I will now point out some circumstances, which are ordinarily different on various parts of one and the same bed. In the first place comes the inequality of the seeds themselves. Some of them will germinate earlier and others later. Those that display their cotyledons on a sunny day will be able to begin at once with the production of organic food. Others appear in bad weather, and will thus be retarded in their development. These effects are of a cumulative nature as the young plants must profit by every hour of sunshine, according to the size of the cotyledons. Any inequality between two young seedlings is apt to be increased by this cumulative effect. The same holds good for the soil of the bed. It is simply impossible to mix the manure so equally that all individuals receive the same amount of it from the very beginning. I am in the habit of using manures in a dry and pulverized condition, of giving definite quantities to each square meter, and of taking the utmost care to get equal distribution and mixture with the soil, always being present myself during this most important operation. Nevertheless it is impossible to make the nourishment exactly equal for all the plants of even a small bed. [382] Any inequality from this cause will increase the difference in the size of the young leaves, augment the inequality of their production of organic matter and for this reason go on in an ever increasing rate. Rain and spraying, or on the other hand dryness of the soil, have still greater consequences. The slightest unevenness of the surface will cause some spots to dry rapidly and others to retain moisture during hours and even sometimes during days. Seeds, germinating in such little moist depressions grow regularly and rapidly, while those on the dryer elevations may be retarded for hours and days, before fully unfurling their seed-leaves. After heavy rains these differences may be observed to increase continually, and in some instances I found that plants were produced only on the wet spots, while the dry places remained perfectly bare. From this the wet spots seem to be the most favorable, but on the other hand, seeds may come to germinate there too numerously and so closely that the young plants will be crowded together and find neither space nor light enough, for a free and perfect development. The advantage may change to disadvantage in this way unless the superfluous individuals are weeded out in due time. [383] From all these and other reasons some plants will be favored by the external conditions from the beginning, while others will be retarded, and the effects will gradually increase until at last they become sufficient to account for a considerable amount of individual variability. There is no doubt that the difference in the strength of the plant and in the size of the capsules, going from 5-10 grams for a single fruit, are for the most part due to these unavoidable circumstances. I have tried all conceivable means to find remedies for these difficulties, but only by sowing my seeds in pans in a glass-house have I been able to reach more constant and equal conditions. But unfortunately such a method requires the planting out of the young seedlings in the beginning of the summer, and this operation is not without danger for opium-poppies, and especially not without important influence on the monstrosity of the pistilloid variety. Consequently my sowings of this plant have nearly always been made in the beds. In order to show how great the influence of all these little things may become, we only have to make two sowings on neighboring beds and under conditions which have carefully been made as equal as possible. If we use for these controlling experiments seeds from one and the same capsule, it will soon become evident that [384] no exact similarity between the two lots may be expected. Such differences as may be seen in these cases are therefore never to be considered of value when comparing two lots of seeds of different origin, or under varying conditions. No amount of accuracy in the estimation of the results of a trial, or in the counting out of the several degrees of the anomaly, is adequate to overcome the inaccuracy resulting from these differences. It is certainly of great importance to have a correct conception in regard to the influence of the surrounding conditions on the growth of a plant and on the development of the attribute we are to deal with. No less important is the question of the sensibility of the plants to these factors. Obviously this sensibility must not be expected to remain the same during the entire life-period, and periods of stronger and of weaker responses may be discerned. In the first place it is evident that external or inner influences are able to change the direction of the development of an organ only so long as this development is not yet fully finished. In the young flower-bud of the pistilloid poppy there must evidently be some moment in which it is definitely decided whether the young stamens will grow out normally or become metamorphosed into secondary pistils. From this [385] moment no further change of external conditions is able to produce a corresponding change in the degree of the anomaly. The individual strength of the whole plant may still be affected in a more or less manifest degree, but the number of converted stamens of the flower has been definitely fixed. The sensitive period has terminated. In order to determine the exact moment of this termination of the period of sensibility, I have followed the development of the flower buds during the first weeks of the life of the young plants. The terminal flower may already be seen in young plants only seven weeks old, with a stem not exceeding 5-6 cm. in height and a flower-bud with a diameter of nearly 1 mm., in which the stamens and secondary pistils are already discernible, but still in the condition of small rounded protuberances on the thalamus. Though it is not possible at that time to observe any difference between the future normal and converted stamens, it does not seem doubtful that the development is so far advanced, that in the inner tissues the decision has already definitely been taken. In the next few days this decision rapidly becomes visible, and the different parts of the normal stamens and the metamorphosed carpels soon become apparent. From this observation it [386] can be inferred that the sensitive period of the anomaly is limited for the terminal flower-head, to the first few weeks of the life of the young plants. The secondary heads manifestly leave this period at a somewhat later stage. In order to prove the accuracy of this conclusion I have tried to injure the anomalies after the expiration of the first six or seven weeks. I deprived them of their leaves, and damaged them in different ways. I succeeded in making them very weak and slender, without being able to diminish the number of the supernumerary carpels. The proportionality of the size of the central fruit and the development of the surrounding crown can often be modified or even destroyed by this means, and the apparent exceptions from this rule, which are often observed, may find their explanation in this way. In the second place I have tried to change the development of the anomaly during the period of sensibility, and even in the last part of it. This experiment succeeded fully when carried out within the fifth or sixth week after the beginning of the germination. As means of injury I transplanted the young plants. To this end I sowed my seeds in pans in unmanured soil, planted them out in little pots with richly prepared earth, grew them in these during a few weeks and afterwards transferred them to the [387] beds, taking care that the pats were removed, but the balls of earth not broken. In consequence of this treatment the plants became very large and strong, with luxuriant foliage and relatively numerous large flowers and fruits. But almost without exception they were poor in anomalous stamens, at least so on the terminal heads. On a lot of some 70 plants more than 50 had less than half a crown of secondary capsules, while from the same packet of seed the control-plants gave in an equal number more than half of filled crowns on all plants with the exception of five weak specimens. It is curious to compare such artificially injured plants with the ordinary cultures. Strong stems and heavy fruits, which otherwise are always indicative of showy crowns, now bear fruits wholly or nearly destitute of any anomalous change. The commonly prevailing rule seems to be reversed, showing thereby the possibility of abolishing the correlation between individual strength and anomaly by an artificial encroachment upon the normal conditions. Aside from these considerations the experiments clearly give proof of the existence of a period of sensibility limited to the first weeks of the life of the plant for the terminal flower. This knowledge enables us to explain many apparent [388] parent abnormalities, which may occur in the experiments. We now may take a broader view of the period of sensibility. Evidently the response to external influences will be greater the younger the organ. Sensibility will gradually diminish, and the phenomena observed in the last part of this period may be considered as the last remainder of a reaction which previously must have been much stronger and much readier, providing that it would be possible to isolate them from, and contrast them with, the other responses of the same plant. With the light thus cast upon the question, we may conclude that the sensitive period commences not only at the beginning of the germination, but must also be considered to include the life of the seed itself. From the moment of fertilization and the formation of the young embryo the development must be subjected to the influence of external agencies which determine the direction it will take and the degree of development it will finally be able to acquire. Probably the time of growth of the embryo and of the ripening of the seed correspond exactly to the period of highest sensibility. This period is only interrupted during the resting stage of the seed, to be repeated in germination. Afterwards the sensibility [389] slowly and gradually decreases, to end with the definite decision of all further growth sometime before the outer form of the organ becomes visible under the microscope. The last period of life includes only an expansion of the tissues, which may still have some influence on their final size, but not on their form. This has been definitely arrested before the end of the sensitive period, and ordinarily before the commencement of that rapid development, which is usually designated by the name of growth, as contrasted with evolution. Within the seed the evolution of the young plant manifestly depends upon the qualities and life-conditions of the parent-plant. The stronger this is, and the more favorable circumstances it is placed under, the more food will be available for the seed, and the healthier will be the development of the embryo. Only well-nourished plants give well-nourished seeds, and the qualities of each plant are for this reason at least, partly dependent on the properties of its parents and even of its grandparents. From these considerations the inference is forced upon us that the apparently hereditary differences, which are observed to exist among the seeds of a species or a variety and even of a single strain or a single parent-plant, may for a large part, and perhaps wholly, be the result [390] of the life-conditions of their parents and grandparents. Within the race all ssvariability would in this way be reduced to the effects of external circumstances. Among these nourishment is no doubt the most momentous, and this to such a degree that older writers designated the external conditions by the term nourishment. According to Knight nutrition reigns supreme in the whole realm of variability, the kind of food and the method of nourishment coming into consideration only in a secondary way. The amount of useful nutrition is the all-important factor. If this is so, and if nutrition decides the degree of deviation of any given character, the widest deviating individuals are the best nourished ones. The best nourished not only during the period of sensibility of the attribute under consideration, but also in the broadest sense of the word. This discussion casts a curious light upon the whole question of selection. Not of course upon the choice of elementary species or varieties out of the original motley assembly which nature and old cultures offer us, but upon the selection of the best individuals for isolation and for the improvement of the race. These are, according to my views, only the best nourished ones. Their external conditions have been the [391] most favorable, not only from the beginning of their own life in the field, but also during their embryonic stages, and even during the preparation of these latter in the life of their parents and perhaps even their grandparents. Selection then, would only be the choice of the best nourished individuals. In connection with the foregoing arguments I have tried to separate the choicest of the poppies with the largest crown of pistilloid stamens, from the most vigorous individuals. As we have already seen, these two attributes are as a rule proportional to one another. Exceptions occur, but they may be explained by some later changes in the external circumstances, as I have also pointed out. As a rule, these exceptions are large fruits with comparatively too few converted stamens; they are exactly the contrary from what is required for a selection. Or plants, which from the beginning were robust, may have become crowded together by further growth, and for these reasons become weaker than their congeners, though retaining the full development of the staminodal crown, which was fixed during the sensitive period and before the crowding. I have searched my beds yearly for several years in vain to find individuals which might recommend themselves for selection without having the stamp of permanent, [392] or at least temporarily better, nourishment. No starting-point for such an independent selection has ever been met with. Summing up the consequences of this somewhat extended discussion, we may state it as a rule that a general proportion between the individual strength and the degree of development of the anomaly exists. And from this point of view it is easy to see that all external causes which are known to affect the one, must be expected to influence the other also. It will therefore hardly be necessary to give a full description of all my experiments on the relations of the monstrosity to external conditions. A hasty survey will suffice. This survey is not only intended to convey an idea of the relations of pistilloid poppies to their environment, but may serve as an example of the principle involved. According to my experience with a large range of other anomalies, the same rule prevails everywhere. And this rule is so simple that exact knowledge of one instance may be considered as sufficient to enable us to calculate from analogy what is to be expected from a given treatment of any other anomaly. Our appreciation of observed facts and the conditions to be chosen for intended cultures are largely dependent on such calculations. What I am now going to describe [393] is to be considered therefore as an experimental basis for such expectations. First of all comes the question how many individuals are to be grown in a given place. When sowing plants for experimental purposes it is always best to sow in rows, and to give as few seeds to each row as possible, so as to insure all necessary space to the young plants. On the other hand the seeds do not all germinate, and after sowing too thinly, gaps may appear in the rows. This would cause not only a loss of space, but an inequality between the plants in later life, as those nearest the gaps would have more space and more light, and a larger area for their roots than those growing in the unbroken rows. Hence the necessity of using large quantities of seed and of weeding out a majority of young plants on the spots where the greatest numbers germinate. Crowded cultures as a rule, will give weak plants with thin stems, mostly unbranched and bearing only small capsules. According to the rule, these will produce imperfect crowns of secondary pistils. The result of any culture will thus be dependent to a high degree on the number of individuals per square meter. I have sown two similar and neighboring beds with the thoroughly mixed seeds of parent-plants of the same strain and culture, using as much [394] as 2.5 cu. cm. per square meter. On one of the beds I left all the germinating plants untouched and nearly 500 of them flowered, but among them 360 were almost without pistillody, and only 10 had full crowns. In the other bed I weeded away more than half of the young plants, leaving only some 150 individuals and got 32 with a full crown, nearly 100 with half crowns and only 25 apparently without monstrosity. These figures are very striking. From the same quantity of seed, in equal spaces, by similar exposure and treatment I got 10 fully developed instances in one and 32 in the other case. The weeding out of supernumerary individuals had not only increased the percentage of bright crowns, but also their absolute number per square meter. So the greatest number of anomalies upon a given space may be obtained by taking care that not too many plants are grown upon it: any increase of the number beyond a certain limit will diminish the probability of obtaining these structures. The most successful cultures may be made after the maximum number of individuals per unit of area has been determined. A control-experiment was made under the same conditions and with the same seed, but allowing much less for the same space. I sowed only 1 cu. cm. on my bed of 2 square meters, and thereby avoided [395] nearly all weeding out. I got 120 plants, and among them 30 with full crowns of converted stamens, practically the same number as after the weeding out in the first experiment. This shows that smaller quantities of seed give an equal chance for a greater number of large crowns, and should therefore always be preferred, as it saves both seed and labor. Weeding out is a somewhat dangerous operation in a comparative trial. Any one who has done it often, knows that there is a strong propensity to root out the weaker plants and to spare the stronger ones. Obviously this is the best way for ordinary purposes, but for comparisons evidently one should not discriminate. This rule is very difficult in practice, and for this reason one should never sow more than is absolutely required to meet all requirements. Our second point is the manuring of the soil. This is always of the highest importance, both for normal and for anomalous attributes. The conversion of the stamens into pistils is in a large measure dependent upon the conditions of the soil. I made a trial with some 800 flowering plants, using one sample of seed, but sowing one-third on richly manured soil, one-third on an unprepared bed of my garden, and one-third on nearly pure sand. In all other respects the three groups were treated in the same way. Of [396] the manured plants one-half gave full crowns, of the non-manured only one-fifth, and on the sandy soil a still smaller proportion. Other trials led to the same results. I have often made use of steamed and ground horn, which is a manure very rich in nitrogenous substances. One-eighth of a kilo per square meter is an ample amount. And its effect was to increase the number of full crowns to an exceptional degree. In the controlling trial and under ordinary circumstances this figure reached some 50%, but with ground horn it came up as high as 90%. We may state this result by the very striking assertion that the number of large crowns in a given culture may be nearly doubled by rich manure. All other external conditions act in a similar manner. The best treatment is required to attain the best result. A sunny exposure is one of the most essential requisites, and in some attempts to cultivate my poppies in the shade, I found the pistillody strongly reduced, not a single full crown being found in the whole lot. Often the weather may be hurtful, especially during the earlier stages of the plants. I protected my beds during several trials by covering them with glass for a few weeks, until the young plants reached the glass covering. I got a normal number of full crowns, some 55%, at a time [397] when the weather was so bad as to reduce the number in the control experiments to 10%. It would be quite superfluous to give more details or to describe additional experiments. Suffice to say, that the results all point in the same direction, and that pistillody of the poppies always clearly responds to the treatment, especially to external conditions during the first few weeks, that is, during the period of sensitiveness. The healthier and the stronger the plants the more fully they will develop their anomaly. In conclusion something is to be said about the choice of the seed. Obviously it is possible to compare seeds of different origin by sowing and treating them in the same way, giving attention to all the points above mentioned. In doing so the first question will be, whether there is a difference between the seeds of strong plants with a bright crown around the head and those of weaker individuals with lesser development of the anomaly. It is evident that such a difference must be expected, since the nutrition of the seed takes place during the period of the greatest sensitiveness. But the experiments will show whether this effect holds good against the influences which tend to change the direction of the development of the anomaly during the time of germination. [398] The result of my attempt has shown that the choice of the seeds has a manifest influence upon the ultimate development of the monstrosity, but that this influence is not strong enough to overwhelm all other factors. The choice of the fullest or smallest crowns may be repeated during succeeding generations, and each time compared with a culture under average conditions. By this means we come to true selection-experiments, and these result in a notable and rapid change of the whole strain. By selecting the brightest crowns I have come up in three years from 40 to 90 and ultimately to 120 converted stamens in the best flower of my culture, and in selecting the smallest crowns I was able in three years to exclude nearly all good crowns, and to make cultures in which heads with less than half-filled crowns constituted the majority. But such selected strains always remain very sensitive to treatment, and by changing the conditions the effect may be wholly lost in a single year, or even turned in the contrary direction. In other words, the anomaly is more dependent on external conditions during the germinating period than on the choice of the seeds, providing these belong to the pistilloid variety and have not deteriorated by some crossing with other sorts. At the beginning of this lecture I stated that [399] no selection is adequate to produce either a pure strain of brightly crowned flower-heads without atavism, or to conduce to an absolute and permanent loss of the anomaly. During a series of years I have tested my plants in both directions, but without the least effect. Limits are soon reached on both sides, and to transgress these seems quite impossible. Taking these limits as the marks of the variety, and considering all fluctuations between them as responses to external influences working during the life of the individual or governing the ripening of the seeds, we get a clear picture of a permanent ever-sporting type. The limits are absolutely permanent during the whole existence of this already old variety. They never change. But they include so wide a range of variability, that the extremes may be said to sport into one another, so much the more so as one of the extremes is to be considered morphologically as the type of the variation, while the other extreme can hardly be distinguished from the normal form of the species. [400] LECTURE XIV MONSTROSITIES I have previously dealt with the question of the hereditary tendencies that cause monstrosities. These tendencies are not always identical for the same anomaly. Two different types may generally, be distinguished. One of them constitutes a poor variety, the other a rich one. But this latter is abundant and the first one is poor in instances of exactly the same conformation. Therefore the difference only lies in the frequency of the anomaly, and not in its visible features. In discovering an instance of any anomaly it is therefore impossible to tell whether it belongs to a poor or to a rich race. This important question can only be answered by direct sowing-experiments to determine the degree of heredity. Monstrosities are often considered as accidents, and rightfully so, at least as long as they are considered from a morphological point of view. Physiology of course excludes all accidentality. And in our present ease it shows [401] that some internal hereditary quality is present, though often latent, and that the observed anomalies are to be regarded as responses of this innate tendency to external conditions. Our two types differ in the frequency of these responses. Rare in the poor race, they are numerous in the rich variety. The external conditions being the same for both, the hereditary factor must be different. The tendency is weak in the one and strong in the other. In both cases, according to my experience, it may be weakened or strengthened by selection and by treatment. Often to a very remarkable degree, but not so far as to transgress the limits between the two races. Such transgression may apparently be met with from time to time, but then the next generation generally shows the fallacy of the conclusion, as it returns more or less directly to the type from which the strain had been derived. Monstrosities should always be studied by physiologists from this point of view. Poor and rich strains of the same anomaly seem at first sight to be so nearly allied that it might be thought to be very easy to change the one into the other. Nevertheless such changes are not on record, and although I have made several attempts in this line, I never succeeded in passing the limit. I am quite convinced that sometime [402] a method will be discovered of arbitrarily producing such conversions, and perhaps the easiest way to attain artificial mutations may lie concealed here. But as yet not the slightest indication of this possibility is to be found, save the fallacious conclusions drawn from too superficial observations. Unfortunately the poor strains are not very interesting. Their chance of producing beautiful instances of the anomaly for which they are cultivated is too small. Exceptions to this rule are only afforded by those curious and rare anomalies, which command general attention, and of which, therefore, instances are always welcome. In such cases they are searched for with perseverance, and the fact of their rarity impresses itself strongly on our mind. Twisted stems are selected as a first example. This monstrosity, called _biastrepsis_, consists of strongly marked torsions as are seen in many species with decussate leaves, though as a rule it is very rare. Two instances are the most generally known, those of the wild valerian (_Valeriana officinalis_) and those of cultivated and wild sorts of teasels (_Dipsacus fullonum_, _D. sylvestris_, and others). Both of these I have cultivated during upwards of fifteen years, but with contradictory results. The valerian is a perennial herb, multiplying itself yearly by [403] slender rootstocks or runners producing at their tips new rosettes of leaves and in the center of these the flowering stem. My original plant has since been propagated in this manner, and during several years I preserved large beds with hundreds of stems, in others I was compelled to keep my culture within more restricted limits. This plant has produced twisted stems of the curious shape, with a nearly straight flag of leaves on one side, described by De Candolle and other observers, nearly every year. But only one or two instances of abnormal stems occurred in each year, and no treatment has been found that proved adequate to increase this number in any appreciable manner. I have sown the seeds of this plant repeatedly, either from normal or from twisted stems, but without better results. It was highly desirable to be able to offer instances of this rare and interesting peculiarity to other universities and museums, but no improvement of the race could be reached and I have been constrained to give it up. My twisted valerian is a poor race, and hardly anything can be done with it. Perhaps, in other countries the corresponding rich race may be hidden somewhere, but I have never had the good fortune of finding it. This good fortune however, I did have with the wild teasel or _Dipsacus sylvestris_. [404] Stems of this and of allied species are often met with and have been described by several writers, but they were always considered as accidents and nobody had ever tried to cultivate them. In the summer of 1885 I saw among a lot of normal wild teasels, two nicely twisted stems in the botanical garden of Amsterdam. I at once proposed to ascertain whether they would yield a hereditary race and had all the normal individuals thrown away before the flowering time. My two plants flowered in this isolated condition and were richly pollinated by insects. Of course, at that time, I knew nothing of the dependency of monstrosities on external conditions, and made the mistake of sowing the seeds and cultivating the next generation in too great numbers on a small space. But nevertheless the anomaly was repeated, and the aberrant individuals were once more isolated before flowering. The third generation repeated the second, but produced sixty twisted stems on some 1,600 individuals. The result was very striking and quite sufficient for all further researches, but the normal condition of the race was not reached. This was the case only after I had discovered the bad effects of growing too many plants in a limited space. In the fourth generation I restricted my whole culture to about 100 individuals, and by this simple [405] means at once got up to 34% of twisted stems. This proportion has since remained practically the same. I have selected and isolated my plants during five succeeding generations, but without any further result, the percentage of twisted stems fluctuating between 30 and about 45 according to the size of the cultures and the favorableness or unfavorableness of the weather. It is very interesting to note that all depends on the question whether one has the good fortune of finding a rich race or not, as this pedigree-culture shows. Afterwards everything depends on treatment and very little on selection. As soon as the treatment becomes adequate, the full strength of the race at once displays itself, but afterwards no selection is able to improve it to any appreciable amount. Of course, in the long run, the responses will be the same as those of the pistilloid poppies on the average, and some influence of selection will show itself on closer scrutiny. Compared with the polycephalous poppies my race of twisted teasels is much richer in atavists. They are never absent, and always constitute a large part of each generation and each bed, comprising somewhat more than half of the individuals. Intermediate stages between them and the wholly twisted stems are not wanting, [406] and a whole series of steps may easily be observed from sufficiently large cultures. But they are always relatively rare, and any lot of plants conveys the idea of a dimorphous race, the small twisted stems contrasting strongly with the tall straight ones. A sharper contrast between good representatives of a race and their atavists is perhaps to be seen in no other instance. All the details contribute to the differentiation in appearance. The whole stature of the plants is affected by the varietal mark. The atavists are not, as in the case of the poppies, obviously allied with the type by a full range of intermediate steps, but quite distant from it by their rarity. There seems to be a gap in the same way as between the striped flowers of the snapdragon and their uniform red atavists, while with the poppies the atavists may be viewed as being only the extremes of a series of variations fluctuating around some average type. From this reason it is as interesting to appreciate the hereditary position of the atavists of twisted varieties as it was for the red-flowered descendants of the striped flowers. In order to ascertain this relation it is only necessary to isolate some of them during the blooming-period. I made this experiment in the summer of 1900 with the eighth generation of my race, and contrived [407] to isolate three groups of plants by the use of parchment bags, covering them alternately, so the flowers of only one group were accessible to insects, at a time. I made three groups, because the atavists show two different types. Some specimens have decussate stems, others bear all their leaves in whorls of three, but in respect to the hereditary tendency of the twisting character this difference does not seem to be of any importance. In this way I got three lots of seeds and sowed enough of them to have three groups of plants each containing about 150-200 well developed stems. Among these I counted the twisted individuals, and found nearly the same numbers for all three. The twisted parents gave as many as 41% twisted children, but the decussate atavists gave even somewhat more, viz., 44%, while the ternate specimens gave 37%. Obviously the divergences between these figures are too slight to be dwelt upon, but the fact that the atavists are as true or nearly as true inheritors of the twisted race as the best selected individuals is clearly proved by this experience. It is evident that here we have a double race, including two types, which may be combined in different degrees. These combinations determine a wide range of changes in the stature of the plants, and it seems hardly right to use the [408] same term for such changes as for common variations. It is more a contention of opposite characters than a true phenomenon of simple variability. Or perhaps we might say that it is the effect of the cooperation of a very variable mark, the twisting, with a scarcely varying attribute of the normal structure of the stem. Between the two types an endless diversity prevails, but outwardly there are limits which are never transgressed. The double race is as permanent, and in this sense as constant, as any ordinary simple variety, both in external form, and in its intimate hereditary qualities. I have succeeded in discovering some other rich races of twisted plants. One of them is the Sweet William (_Dianthus barbatus_), which yielded, after isolation, in the second generation, 25% of individuals with twisted stems, and as each individual produces often 10 and more stems, I had a harvest of more than half a thousand of instances of this curious, and ordinarily very rare anomaly. My other race is a twisted variety of _Viscaria oculata_, which is still in cultivation, as it has the very consistent quality of being an annual. It yielded last summer (1903) as high a percentage as 65 of twisted individuals, many of them repeating the monstrosity on several branches. After some occasional observations _Gypsophila paniculata_ [409] seems to promise similar results. On the other hand I have sowed in vain the seeds of twisted specimens of the soapwort and the cleavewort (_Saponaria officinalis_ and _Galium Aparine_). These and some others seem to belong to the same group as the valerian and to constitute only poor or so-called half-races. Next to the torsions come the fasciated stems. This is one of the most common of all malformations, and consists, in its ordinary form, of a flat ribbon-like expansion of the stems or branches. Below they are cylindrical, but they gradually lose this form and assume a flattened condition. Sometimes the rate of growth is unequal on different portions or on the opposite sides of the ribbon, and curvatures are produced and these often give to the fasciation a form that might be compared with a shepherd's crook. It is a common thing for fasciated branches and stems to divide at the summit into a number of subdivisions, and ordinarily this splitting occurs in the lower part, sometimes dividing the entire fasciated portion. In biennial species the rosette of the root-leaves of the first year may become changed by the monstrosity, the heart stretching in a transverse direction so as to become linear. In the next year this line becomes the base from which the stem grows. In such cases the fasciated stems [410] are broadened and flattened from the very beginning, and often retain the incipient breadth throughout their further development. Species of primroses (_Primula japonica_ and others), of buttercups (_Ranunculus bulbosus_), the rough hawksbeard (_Crepis biennis_), the Aster _Tripolium_, and many others could be given as instances. Some of these are so rare as to be considered as poor races, and in cultural trials do not produce the anomaly except in a very few instances. Heads of rye are found in a cleft condition from time to time, single at their base and double at the top, but this anomaly is only exceptionally repeated from seed. Flattened stems of _Rubia tinctorum_ are not unfrequently met with on the fields, but they seem to have as little hereditary tendency as the split rye (_Secale Cereale_). Many other instances could be given. Both in the native localities and in pedigree-cultures such ribboned stems are only seen from time to time, in successive years, in annual and biennial as well as in perennial species. The purple pedicularis (_Pedicularis palustris_) in the wild state, and the sunflower among cultivated plants, may be cited instead of giving a long list of analogous instances. On the other hand rich races of flattened stems are not entirely lacking. They easily betray [411] themselves by the frequency of the anomaly, and therefore may be found, and tried in the garden. Under adequate cultivation they are here as rich in aberrant individuals as the twisted races quoted above, producing in good years from 30-40% and often more instances. I have cultivated such rich races of the dandelion (_Taraxacum officinale_), of _Thrincia hirta_, of the dame's violet (_Hesperis matronalis_), of the hawkweed (_Picris hieracioides_), of the rough hawksbeard (_Crepis biennis_), and others. Respecting the hereditary tendencies these rich varieties with flattened stems may be put in the same category with the twisted races. Two points however, seem to be of especial interest and to deserve a separate treatment. The common cockscomb or _Celosia cristata_, one of the oldest and most widely cultivated fasciated varieties may be used to illustrate the first point. In beds it is often to be seen in quite uniform lots of large and beautiful crests, but this uniformity is only secured by careful culture and selection of the best individuals. In experimental trials such selection must be avoided, and in doing so a wide range of variability at once shows itself. Tall, branched stems with fan-shaped tops arise, constituting a series of steps towards complete atavism. This last [412] however, is not to be reached easily. It often requires several successive generations grown from seed collected from the most atavistic specimens. And even such selected strains are always reverting to the crested type. There is no transgression, no springing over into a purely atavistic form, such as may be supposed to have once been the ancestor of the present cockscomb. The variety includes crests and atavists, and may be perpetuated from both. Obviously every gardener would select the seeds of the brightest crests, but with care the full crests may be recovered, even from the worst reversionists in two or three generations. It is a double race of quite the same constitution as the twisted teasels. My second point is a direct proof of this assertion, but made with a fasciated variety of a wild species. I took for my experiment the rough hawksbeard. In the summer of 1895 I isolated some atavists of the fifth generation of my race, which, by ordinary selection, gave in the average from 20-40% of fasciated stems. My isolated atavists bore abundant fruit, and from these I had the next year a set of some 350 plants, out of which about 20% had broadened and linear rosettes. This proportion corresponds with the degree of inheritance which is shown in many years by the largest and strongest [413] fasciated stems. It strengthens our conclusion as to the innermost constitution of the double races or ever-sporting varieties. Twisted stems and fasciations are very striking monstrosities. But they are not very good for further investigation. They require too much space and too much care. The calculation of a single percentage requires the counting of some hundreds of individuals, taking many square meters for their cultivation, and this, as my best races are biennial, during two years. For this reason the countings must always be very limited, and selection is restrained to the most perfect specimens. Now the question arises, whether this mark is the best upon which to found selection. This seems to be quite doubtful. In the experiments on the heredity of the atavists, we have seen that they are, at least often, in no manner inferior to even the best inheritors of the race. This suggests the idea that it is not at all certain that the visible characters of a given individual are a trustworthy measure of its value as to the transmission of the same character to the offspring. In other words, we are confronted with the existence of two widely different groups of characters in estimating the hereditary tendency. One is the visible quality of the individuals and the other is the direct observation [414] of the degree in which the attribute is transmitted. These are by no means parallel, and seem in some sense to be nearly independent of each other. The fact that the worst atavists may have the highest percentage of varietal units seems to leave no room for another explanation. Developing this line of thought, we gradually arrive at the conclusion that the visible attribute of a varying individual is perhaps the most untrustworthy and the most unreliable character for selection, even if it seems in many cases practically to be the only available one. The direct determination of the degree of heredity itself is obviously preferable by far. This degree is expressed by the proportion of its inheritors among the offspring, and this figure therefore should be elevated to the highest rank, as a measure of the hereditary qualities. Henceforward we will designate it by the name of hereditary percentage. In scientific experiments this figure must be determined for every plant of a pedigree-culture singly, and the selection should be founded exclusively or at least mainly on it. It is easily seen that this method requires large numbers of individuals to be grown and counted. Some two or three hundred progeny of one plant are needed to give the decisive figure for this one [415] individual, and selection requires the comparison of at least fifty or more individuals. This brings the total amount of specimens to be counted up to some tens of thousands. In practice, where important interests depend upon the experiments, such numbers are usually employed and often exceeded, but for the culture of monstrosities, other methods are to be sought in order to avoid these difficulties. The idea suggests itself here that the younger the plants are, when showing their distinguishing marks, the more of them may be grown on a small space. Hence the best way is to choose such attributes, as may already be seen in the young seedlings, in the very first few weeks of their lives. Fortunately the seed-leaves themselves afford such distinctive marks, and by this means the plants may be counted in the pans, requiring no culture at all in the garden. Only the selected individuals need be grown to ripen their seeds, and the whole selection may be made in the spring, in the glasshouse. Instead of being very troublesome, the determination of the hereditary percentages becomes a definite reduction of the size of the experiments. Moreover it may easily be effected by any one who cares for experimental studies, but has not the means required for cultures on a larger scale. And lastly, there are [416] a number of questions about heredity, periodicity, dependency on nourishment and other life conditions, and even about hybridizing, which may be answered by this new method. Seed-leaves show many deviations from the ordinary shape, especially in dicotyledonous plants. A very common aberration is the multiplication of their number, and three seed-leaves in a whorl are not rarely met with. The whorl may even consist of four, and in rare cases of five or more cotyledons. Cleft cotyledons are also to be met with, and the fissure may extend varying distances from the tips. Often all these deviations may be seen among the seedlings of one lot, and then it is obvious that together they constitute a scale of cleavages, the ternate and quaternate whorls being only cases where the cleaving has reached its greatest development. All in all it is manifest that here we are met by one type of monstrosity, but that this type allows of a wide range of fluctuating variability. For brevity's sake all these cleft and ternate, double cleft and quaternate cotyledons and even the higher grades are combined under one common name and indicated as tricotyls. A second aberration of young seed-plants is exactly opposite to this. It consists of the union of the two seed-leaves into a single organ. This ordinarily betrays its origin by [417] having two separate apices, but not always. Such seedlings are called syncotyledonous or syncotyls. Other monstrosities have been observed from time to time, but need not be mentioned here. It is evident that the determination of the hereditary percentage is very easy in tricotylous or syncotylous cultures. The parent plants must be carefully isolated while blooming. Many species pollinate themselves in the absence of bees; from these the insects are to be excluded. Others have the stamens and stigmas widely separated and have to be pollinated artificially. Still others do not lend themselves to such operations, but have to be left free to the visits of bees and of humble-bees, this being the only means of securing seed from every plant. At the time of the harvest the seeds should be gathered separately from each plant, and this precaution should also be observed in studies of the hereditary percentage at large, and in all scientific pedigree-cultures. Every lot of seeds is to be sown in a separate pan, and care must be taken to sow such quantities the three to four hundred seedlings will arise from each. As soon as they display their cotyledons, they are counted, and the number is the criterion of the parent-plant. Only parent-plants with the highest percentages are selected, and out of [418] their seedlings some fifty or a hundred of the best ones are chosen to furnish the seeds for the next generation. This description of the method shows that the selection is a double one. The first feature is the hereditary percentage. But then not all the seedlings of the selected parents can be planted out, and a choice has to be made. This second selection may favor the finest tricotyls, or the strongest individuals, or rely on some other character, but is unavoidable. We now come to the description of the cultures. Starting points are the stray tricotyls which are occasionally found in ordinary sowings. In order to increase the chance of finding them, thousands of seeds of the same species must be inspected, and the range of species must be widened as much as possible. Material for beginning such experiments is easily obtained, and almost any large sample of seeds will be found suitable. Some tricotyls will be found among every thousand seedlings in many species, while in others ten or a hundred times, as many plants must be examined to secure them, but species with absolutely pure dicotylous seeds are very rare. The second phase of the experiment, however, is not so promising. Some species are rich, and others are poor in this anomaly. This difference [419] often indicates what can be expected from further culture. Stray tricotyls point to poor species or half-races, while more frequent deviations suggest rich or double-races. In both cases however, the trial must be made, and this requires the isolation of the aberrant individuals and the determination of their hereditary percentage. In some instances the degree of their inheritance is only a very small one. The isolated tricotyls yield 1 or 2% of inheritors, in some cases even less, or upwards up to 3 or 4%. If the experiment is repeated, no amelioration is observed, and this result remains the same during a series of successive generations. In the case of _Polygonum convolvulus_, the Black bindweed, I have tried as many as six generations without ever obtaining more than 3%. With other species I have limited myself to four successive years with the same negative result, as with spinage, the Moldavian dragon-head, (_Dracocephalum moldavicum_), and two species of corn catch-fly (_Silene conica_ and _S. conoidea_). Such poor races hardly afford a desirable material for further inquiries. Happily the rich races, though rare, may be discovered also from time to time. They seem to be more common among cultivated plants and horticultural as well as agricultural species may be used. Hemp [420] and mercury (_Mercurialis annua_) among the first, snapdragon, poppies, _Phacelia_, _Helichrysum_, and _Clarkia_ among garden-flowers may be given as instances of species containing the rich tricotylous double races. It is very interesting to note how strong the difference is between such cases and those which only yield poor races. The rich type at once betrays itself. No repeated selection is required. The stray tricotyls themselves, that are sought out from among the original samples, give hereditary percentages of a much higher type after isolation than those quoted above. They come up to 10-20% and in some cases even to 40%. As may be expected, individual differences occur, and it must even be supposed that some of the original tricotyls may not be pure, but hybrids between tricotylous and dicotylous parents. These are at once eliminated by selection, and if only the tricotyls which have the highest percentages are chosen for the continuance of the new race, the second generation comes up with equal numbers of dicotyls and tricotyls among the seedlings. The figures have been observed to range from 51-58% in the majority of the cases, and average 55%, rarely diverging somewhat more from this average. Here we have the true type of an ever-sporting variety. Every year it produces in the [421] same way heirs and atavists. Every plant, if fertilized with its own pollen, gives rise to both types. The parent itself may be tricotylous or dicotylous, or show any amount of multiplication and cleavage in its seed-leaves, but it always gives the entire range among its progeny of the variation. One may even select the atavists, pollinate them purely and repeat this in a succeeding generation without any chance of changing the result. On an average the atavists may give lower hereditary figures, but the difference will be only slight. Such tricotylous double races offer highly interesting material for inquiries into questions of heredity, as they have such a wide range of variability. There is little danger in asserting that they go upwards to nearly 100%, and downwards to 0%, diverging symmetrically on both sides of their average (50-55%). These limits they obviously cannot transgress, and are not even able to reach them. Samples of seed consisting only of tricotyls are very rare, and when they are met with the presumption is that they are too few to betray the rare aberrants they might otherwise contain. Experimental evidence can only be reached by the culture of a succeeding generation, and this always discloses the hidden qualities, showing that the double [422] type was only temporarily lost, but bound to return as soon as new trials are made. This wide range of variability between definite limits is coupled with a high degree of sensibility and adequateness to the most diverging experiments. Our tricotylous double races are perhaps more sensitive to selection than any other variety, and equally dependent on outer circumstances. Here, however, I will limit myself to a discussion of the former point. In the second generation after the isolation of stray tricotylous seedlings the average condition of the race is usually reached, but only by some of the strongest individuals, and if we continue the race, sowing or planting only from their offspring, the next generation will show the ordinary type of variability, going upwards in some and downwards in other instances. With the _Phacelia_ and the mercury and some others I had the good luck in this one generation to reach as high as nearly 90% of tricotylous seedlings, a figure indicating that the normal dicotylous type had already become rare in the race. In other cases 80% or nearly 80% was easily attained. Any further divergence from the average would have required very much larger sowings, the effect of selection between a limited number of parents being only to retain the high degree once [423] reached; so for instance with the mercury, I had three succeeding generations of selection after reaching the average of 55%, but their extremes gave no increasing advance, remaining at 86, 92 and 91%. If we compare these results with the effects of selection in twisted and fasciated races, we observe a marked contrast. Here they reached their height at 30-40%, and no number of generations had the power of making any further improvement. The tricotyls come up in two generations to a proportion of about 54%, which shows itself to correspond to the average type. And as soon as this is reached, only one generation is required to obtain a very considerable improvement, going up to 80 or even 90%. It is evident that the cause of this difference does not lie in the nature of the monstrosity, but is due to the criterion upon which the selection is made. Selection of the apparently best individuals is one method, and it gives admirable results. Selection on the ground of the hereditary percentages is another method and gives results which are far more advantageous than the former. In the lecture on the pistillody of the poppies we limited ourselves to the selection of the finest individuals and showed that there is always a manifest correlation between the individual [424] strength of the plant and the degree of development of its anomaly. The same holds good with other monstrosities, and badly nourished specimens of rich races with twisted or fasciated stems always tend to reversion. This reversion, however, is not necessarily correlated with the hereditary percentage and therefore does not always indicate a lessening of the degree of inheritance. This shows that even in those cases an improvement may be expected, if only the means can be found to subject the twisted and the fasciated races to the same sharp test as the tricotylous varieties. Much remains to be done, and the principle of the selection of parents according to the average constitution of their progeny seems to be one of the most promising in the whole realm of variability. Besides tricotylous, the syncotylous seedlings may be used in the same way. They are more rarely met with, and in most instances seem to belong only to the unpromising half-races. The black bindweed (_Polygonum Convolvulus_), the jointed charlock (Raphanus Raphanistrum), the glaucous evening-primrose (_Oenothera glauca_) and many other plants seem to contain such half-races. On the other hand I found a plant of _Centranthus macrosiphon_ yielding as much as 55% of syncotylous children [425] and thereby evidently betraying the nature of a rich or double race. Likewise the mercury was rich in such deviations. But the best of all was the Russian sunflower, and this was chosen for closer experiments. In the year of 1888 I had the good luck to isolate some syncotylous seedlings and of finding among them one with 19% of inheritors among its seeds. The following generation at once surpassed the ordinary average and came up in three individuals to 76, 81 and even 89%. My race was at once isolated and ameliorated by selection. I have tried to improve it further and selected the parents with the highest percentages during seven more generations; but without any remarkable result. I got figures of 90% and above, coming even in one instance up to the apparent purity of 100%. These, however, always remained extremes, the averages fluctuating yearly between 80-90% or thereabouts, and the other extremes going nearly every year downwards to 50%, the value which would be attained, if no selection were made. Contra-selection is as easily made as normal selection. According to our present principle it means the choice of the parents with the smallest hereditary percentage. One might easily imagine that by this means the dicotylous seedlings could be rendered pure. This, however, [426] is not at all the case. It is easy to return from so highly selected figures as for instance 95% to the average about of 50%, as regression to mediocrity is always an easy matter. But to transgress this average on the lower side seems to be as difficult as it is on the upper side. I continued the experiment during four succeeding generations, but was not able to go lower than about 10%, and could not even exclude the high figures from my strain. Parents with 65-75% of syncotylous seedlings returned in each generation, notwithstanding the most careful contra-selection. The attribute is inherent in the race, and is not to be eliminated by so simple a means as selection, nor even by a selection on the ground of hereditary percentages. We have dealt with torsions and fasciations and with seedling variations at some length, in order to point out the phases needing investigation according to recent views. It would be quite superfluous to consider other anomalies in a similar manner, as they all obey the same laws. A hasty survey may suffice to show what prospects they offer to the student of nature. First of all come the variegated leaves. They are perhaps the most variable of all variations. They are evidently dependent on external circumstances, and by adequate nutrition the leaves may even become absolutely white or [427] yellowish, with only scarcely perceptible traces of green along the veins. Some are very old cultivated varieties, as the wintercress, or _Barbarea vulgaris_. They continuously sport into green, or return from this normal color, both by seeds and by buds. Sports of this kind are very often seen on shrubs or low trees, and they may remain there and develop during a long series of years. Bud-sports of variegated holly, elms, chestnuts, beeches and others might be cited. One-sided variegation on leaves or twigs with the opposite side wholly green are by no means rare. It is very curious to note that variegation is perhaps the most universally known anomaly, while its hereditary tendencies are least known. Cristate and plumose ferns are another instance. Half races or rare accidental cleavages seem to be as common with ferns as cultivated double races, which are very rich in beautiful crests. But much depends on cultivation. It seems that the spores of crested leaves are more apt to reproduce the variety than those of normal leaves, or even of normal parts of the same leaves. But the experiments on which this assertion is made are old and should be repeated. Other cases of cleft leaves should also be tested. Ascidia are far more common than is usually believed. Rare instances point [428] to poor races, but the magnolias and lime-trees are often so productive of ascidia as to suggest the idea of ever-sporting varieties. I have seen many hundred ascidia on one lime-tree, and far above a hundred on the magnolia. They differ widely in size and shape, including in some cases two leaves instead of one, or are composed of only half a leaf or of even still a smaller part of the summit. Rich ascidia-bearing varieties seem to offer notable opportunities for scientific pedigree-cultures. Union of the neighboring fruits and flowers on flower-heads, of the rays of the umbellifers or of the successive flowers of the racemes of cabbages and allied genera, seem to be rare. The same holds good for the adhesion of foliar to axial organs, of branches to stems and other cases of union. Many of these cases return regularly in each generation, or may at least be seen from time to time in the same strains. Proliferation of the inflorescence is very common and changes in the position of staminate and pistillate flowers are not rare. We find starting points for new investigations in almost any teratological structure. Half-races and double-races are to be distinguished and isolated in all cases, and their hereditary qualities, the periodicity of the recurrence of the anomaly, the dependency on external circumstances [429] and many other questions have to be answered. Here is a wide field for garden experiments easily made, which might ultimately yield much valuable information on many questions of heredity of universal interest. [430] LECTURE XV DOUBLE ADAPTATIONS The chief object of all experimentation is to obtain explanations of natural phenomena. Experiments are a repetition of things occurring in nature with the conditions so guarded and so closely followed that it is possible to make a clear analysis of facts and their causes, it being rightfully assumed that the laws are the same in both cases. Experiments on heredity and the experience of the breeder find their analogy in the succession of generations in the wild state. The stability of elementary species and of retrograde varieties is quite the same under both conditions. Progression and retrogression are narrowly linked everywhere, and the same laws govern the abundance of forms in cultivated and in wild plants. Elementary species and retrograde varieties are easily recognizable. Ever-sporting varieties on the contrary are far less obvious, and in many cases their hereditary relations have [431] had to be studied anew. A clear analogy between them and corresponding types of wild plants has yet to be pointed out. There can be no doubt that such analogy exists; the conception that they should be limited to cultivated plants is not probable. Striped flowers and variegated leaves, changes of stamens into carpels or into petals may be extremely rare in the wild state, but the "five-leaved" clover and a large number of monstrosities cannot be said to be typical of the cultivated condition. These, however, are of rare occurrence, and do not play any important part in the economy of nature. In order to attain a better solution of the problem we must take a broader view of the facts. The wide range of variability of ever-sporting varieties is due to the presence of two antagonistic characters which cannot be evolved at the same time and in the same organ, because they exclude one another. Whenever one is active, the other must be latent. But latency is not absolute inactivity and may often only operate to encumber the evolution of the antagonistic character, and to produce large numbers of lesser grades of its development. The antagonism however, is not such in the exact meaning of the word; it is rather a mutual exclusion, because one of the opponents simply takes the place of the other when absent, or supplements [432] it to the extent that it may be only imperfectly developed. This completion ordinarily occurs in all possible degrees and thus causes the wide range of the variability. Nevertheless it may be wanting, and in the case of the double stocks only the two extremes are present. It is rather difficult to get a clear conception of the substitution, and it seems necessary to designate the peculiar relationship between the two characters forming such a pair by a simple name. They might be termed alternating, if only it were clearly understood that the alternation may be complete, or incomplete in all degrees. Complete alternation would result in the extremes, the incomplete condition in the intermediate states. In some cases as with the stocks, the first prevails, while in other cases, as with the poppies, the very extremes are only rarely met with. Taking such an alternation as a real character of the ever-sporting varieties, a wide range of analogous cases is at once revealed among the normal qualities of wild plants. Alternation is here almost universal. It is the capacity of young organs to develop in two diverging directions. The definitive choice must be made in extreme youth, or often at a relatively late period of development. Once made, this [433] choice is final, and a further change does not occur in the normal course of things. The most curious and most suggestive instance of such an alternation is the case of the water-persicaria or _Polygonum amphibium_. It is known to occur in two forms, one aquatic and the other terrestrial. These are recorded in systematic works as varieties, and are described under the names of _P. amphibium_ var. _natans_ Moench, and _P. amphibium_ var. _terrestre_ Leers or _P. amphibium_ var. _terrestris_ Moench. Such authorities as Koch in his German flora, and Grenier and Godron in their French flora agree in the conception of the two forms as varieties. Notwithstanding this, the two varieties may often be observed to sport into one another. They are only branches of the same plant, grown under different conditions. The aquatic form has floating or submerged stems with oblong or elliptic leaves, which are glabrous and have long petioles. The terrestrial plants are erect, nearly simple, more or less hispid throughout, with lanceolate leaves and short petioles, often nearly sessile. The aquatic form flowers regularly, producing its peduncle at right angles from the floating stems, but the terrestrial specimens are ordinarily seen without flower-spikes, which are but rarely met with, at least as far as my own experience goes. Intermediate [434] forms are very rare, perhaps wholly wanting, though in swamps the terrestrial plants may often vary widely in the direction of the floating type. That both types sport into each other has long been recognized in field-observations, and has been the ground for the specific name of _amphibium_, though in this respect herbarium material seems usually to be scant. The matter has recently been subjected to critical and experimental studies by the Belgian botanist Massart, who has shown that by transplanting the forms into the alternate conditions, the change may always be brought about artificially. If floating plants are established on the shore they make ascending hairy stems, and if the terrestrial shoots are submerged, their buds grow into long and slack, aquatic stems. Even in such experiments, intermediates are rare, both types agreeing completely with the corresponding models in the wild state. Among all the previously described cases of horticultural plants and monstrosities there is no clearer case of an ever-sporting variety than this one of the water-persicaria. The var. _terrestris_ sports into the var. _natans_, and as often as the changing life conditions may require it. It is-true that ordinary sports occur without our discerning the cause and without [435] any relation to adaptation. This however is partly due to our lack of knowledge, and partly to the general rule that in nature only such sports as are useful are spared by natural selection, and what is useful we ordinarily term adaptive. Another side of the question remains to be considered. The word variety, as is now becoming generally recognized, has no special meaning whatever. But here it is assumed in the clearly defined sense of a systematic variety, which includes all subdivisions of species. Such subdivisions may be, from a biological point of view, elementary species and also be eversporting varieties. They may be retrograde varieties, and the two alternating types may be described as separate varieties. It is readily granted that many writers would not willingly accept this conclusion. But it is simply impossible to avoid it. The two forms of the water-persicaria must remain varieties, though they are only types of the different branches of a single plant. If not, hundreds and perhaps thousands of analogous cases are at once exposed to doubt, and the whole conception of systematic varieties would have to be thrown over. Biologists of course would have no objection to this, but the student of the flora of any given country [436] or region requires the systematic subdivisions and should always use his utmost efforts to keep them as they are. There is no intrinsic difficulty in the statement that different parts of the same plant should constitute different varieties. In some cases different branches of the same plant have been described as species. So for instance with the climbing forms of figs. Under the name of _Ficus repens_ a fine little plant is quite commonly cultivated as a climber in flower baskets. It is never seen bearing figs. On the other hand a shrub of our hothouses called _Ficus stipulata_, is cultivated in pots and makes a small tree which produces quite large, though non-edible figs. Now these two species are simply branches of the same plant. If the _repens_ is allowed to climb up high along the walls of the hothouses, it will at last produce stipulate branches with the corresponding fruits. _Ficus radicans_ is another climbing form, corresponding to the shrub _Ficus ulmifolia_ of our glasshouses. And quite the same thing occurs with ivy, the climbing stems of which never flower, but always first produce erect and free branches with rhombic leaves. These branches have often been used as cuttings and yield little erect and richly flowering shrubs, which are known in [437] horticulture under the varietal name of _Hedera Helix arborea_. Manifestly this classification is as nearly right as that of the two varieties of the water-persicaria. Going one step further, we meet with the very interesting case of alpine plants. The vegetation of the higher regions of mountains is commonly called alpine, and the plants show a large number of common features, differentiating them from the flora of lower stations. The mountain plants have small and dense foliage, with large and brightly-colored flowers. The corresponding forms of the lowlands have longer and weaker stems, bearing their leaves at greater distances, the leaves themselves being more numerous. The alpine forms, if perennial, have thick, strongly developed and densely branched rootstocks with heavy roots, in which a large amount of food material is stored up during the short summer, and is available during the long winter months of the year. Some species are peculiar to such high altitudes, while many forms from the lowlands have no corresponding type on the mountains. But a large number of species are common to both regions, and here the difference of course is most striking. _Lotus corniculatus_ and _Calamintha Acinos_, _Calluna vulgaris_ and _Campanula_ [438] _rotundifolia_ may be quoted as instances, and every botanist who has visited alpine regions may add other examples. Even the edelweiss of the Swiss Alps, _Gnaphalium Leontopodium_, loses its alpine characters, if cultivated in lowland gardens. Between such lowland and alpine forms intermediates regularly occur. They may be met with whenever the range of the species extends from the plains upward to the limit of eternal snow. In this case the systematists formerly enumerated the alpine plants as _forma alpestris_, but whenever the intermediate is lacking the term _Varietas alpestris_ was often made use of. It is simply impossible to decide concerning the real relation between the alpine and lowland types without experiments. About the middle of the last century it was quite a common thing to collect plants not only for herbarium-material, but also for the purpose of planting them in gardens and thus to observe their behavior under new conditions. This was done with the acknowledged purpose of investigating the systematic significance of observed divergencies. Whenever these held good in the garden they were considered to be reliable, but if they disappeared they were regarded as the results of climatic conditions, or of the influence of soil or nourishment. Between [439] these two alternatives, many writers have tried to decide, by transplanting their specimens after some time in the garden, into arid or sandy soil, in order to see whether they would resume their alpine character. Among the systematists who tested plants in this way, Nageli especially, directed his attention to the hawkweeds or _Hieracium_. On the Swiss Alps they are very small and exhibit all the characters of the pure alpine type. Thousands of single plants were cultivated by him in the botanical garden of Munich, partly from seed and partly from introduced rootstocks. Here they at once assumed the tall stature of lowland forms. The identical individual, which formerly bore small rosettes of basal leaves, with short and unbranched flower-stalks, became richly leaved and often produced quite a profusion of flower-heads on branched stems. If then they were transplanted to arid sand, though remaining in the same garden and also under the same climatic conditions they resumed their alpine characters. This proved nutrition to be the cause of the change and not the climate. The latest and most exact researches on this subject are due to Bonnier, who has gone into all the details of the morphologic as well as of the physiologic side of the problem. [440] His purpose was the study of partial variability under the influence of climate and soil. In every experiment he started from a single individual, divided it into two parts and planted one half on a mountain and the other half on the plain. The garden cultures were made chiefly at Paris and Fontainebleau, the alpine cultures partly in the Alps, partly in the Pyrenees. From time to time the halved plants were compared with each other, and the cultures lasted, as a rule, during the lifetime of the individual, often covering many years. The common European frostweed or _Helianthemum vulgare_ will serve to illustrate his results. A large plant growing in the Pyrenees in an altitude of 2,400 meters was divided. One half was replanted on the same spot, and the other near Cadeac, at the base of the mountain range (740 M.). In order to exclude the effect of a change of soil, a quantity of the earth from the original locality was brought into the garden and the plant put therein. Further control experiments were made at Paris. As soon as the two halved individuals commenced to grow and produced new shoots, the influence of the different climates made itself felt. On the mountain, the underground portions remained strong and dense, the leaves and internodes small and hairy, the flowering stems nearly [441] procumbent, the flowers being large and of a deep yellow. At Cadeac and at Paris the whole plant changed at once, the shoots becoming elongated and loose, with broad and flattened, rather smooth leaves and numerous pale-hued flowers. The anatomical structure exhibited corresponding differences, the intercellular spaces being small in the alpine plant and large in the one grown in the lowlands, the wood-tissues strong in the first and weak in the second case. The milfoil (_Achillea Millefolium_) served as a second example, and the experiments were carried on in the same localities. The long and thick rootstocks of the alpine plant bearing short stems only with a few dense corymbs contrasted markedly with the slender stems, loose foliage and rich groups of flowerheads of the lowland plant. The same differences, in inner and outer structures were observed in numerous instances, showing that the alpine type in these cases is dependent on the climate, and that the capacity for assuming the antagonistic characters is present in every individual of the species. The external conditions decide which of them becomes active and which remains inactive, and the case seems to be exactly parallel to that of the water-persicaria. In the experiments of Bonnier the influence of the soil was, as a rule, excluded by transplanting [442] part of the original earth with the transplanted half of the plant. From this he concluded that the observed changes were due to the inequality of the climate. This involved three main factors, light, moisture and temperature. On the mountains the light is more intense, the air drier and cooler. Control-experiments were made on the mountains, depriving the plants of part of the light. In various ways they were more or less shaded, and as a rule responded to this treatment in the same way as to transplantation to the plain below. Bonnier concluded that, though more than one factor takes part in inciting the morphologic changes, light is to be considered as the chief agency. The response is to be considered as a useful one, as the whole structure of the alpine varieties is fitted to produce a large amount of organic material in a short time, which enables the plants to thrive during the short summers and long winters of their elevated stations. In connection with these studies on the influences of alpine climates, Bonnier has investigated the internal structure of arctic plants, and made a series of experiments on growth in continuous electric light. The arctic climate is cold, but wet, and the structure of the leaves is correspondingly loose, though the plants become [443] as small as on the Alps. Continuous electric light had very curious effects; the plants became etiolated, as if growing in darkness, with the exception that they assumed a deep green tinge. They showed more analogy with the arctic than with the alpine type. The influence of the soil often produces changes similar to that of climate. This was shown by the above cited experiments of Nageli with the hawkweeds, and may easily be controlled in other cases. The ground-honeysuckle or _Lotus corniculatus_ grows in Holland partly on the dry and sandy soil of the dunes, and occasionally in meadows. It is small and dense in the first case, with orange and often very darkly colored petals, while it is loose and green in the meadows, with yellower flowers. Numerous analogous cases might be given. On mountain slopes in South Africa, and especially in Natal, a species of composite is found, which has been introduced into culture and is used as a hanging plant. It is called _Othonna crassifolia_ and has fleshy, nearly cylindrical leaves, and exactly mimics some of the crassulaceous species. On dry soil the leaves become shorter and thicker and assume a reddish tinge, the stems remain short and woody and bear their leaves in dense rosettes. On moist and rich garden-soil this aspect becomes [444] changed at once, the stems grow longer and of a deeper green. Intermediates occur, but notwithstanding this the two extremes constitute clearly antagonistic types. The flora of the deserts is known to exhibit a similar divergent type. Or rather two types, one adapted to paucity of water, and the other to a storage of fluid at one season in order to make use of it at other times, as is the case with the cactuses. Limiting ourselves to the alternate group, we observe a rich and dense branching, small and compact leaves and extraordinarily long roots. Here the analogy with the alpine varieties is manifest, and the dryness of the soil evidently affects the plants in a similar way, as do the conditions of life in alpine regions. The question at once comes up as to whether here too we have only instances of partial variability, and whether many of the typical desert-species would lose their peculiar character by cultivation under ordinary conditions. The varieties of _Monardella macrantha_, described by Hall, from the San Jacinto Mountain, Cal., are suggestive of such an intimate analogy with the cases studied by Bonnier, that it seems probable that they might yield similar results, if tested by the same method. Leaving now the description of these special [445] cases, we may resume our theoretical discussion of the subject, and try to get a clearer insight into the analogy of ever-sporting varieties and the wild species quoted. All of them may be characterized by the general term of dimorphism. Two types are always present, though not in the same individual or in the same organ. They exclude one another, and during their juvenile stage a decision is taken in one direction or in the other. Now, according to the theory of natural selection, wild species can only retain useful or at least innocuous qualities, since all mutations in a wrong direction must perish sooner or later. Cultivated species on the other hand are known to be largely endowed with qualities, which would be detrimental in the wild condition. Monstrosities are equally injurious and could not hold their own if left to themselves. These same principles may be applied to ever-sporting or antagonistic pairs of characters. According to the theory of mutations such pairs may be either useful or useless. But only the useful will stand further test, and if they find suitable conditions will become specific or varietal characters. On this conclusion it becomes at once clear, why natural dimorphism is, as a rule, a very useful quality, while the cultivated dimorphous varieties [446] strike us as something unnatural. The relation between cause and effect, is in truth other than it might seem to be at first view, but nevertheless it exists, and is of the highest importance. From this same conclusion we may further deduce some explanation of the hereditary races characterized by monstrosities. It is quite evident that the twisted teasels are inadequate for the struggle with their tall congeners, or with the surrounding plants. Hence the conclusion that a pure and exclusively twisted race would soon die out. The fact that such races are not in existence finds its explanation in this circumstance, and therefore it does not prove the impossibility or even the improbability that some time a pure twisted race might arise. If chance should put such an accidental race in the hands of an experimenter, it could be protected and preserved, and having no straight atavistic branches, but being twisted in all its organs, might yield the most curious conceivable monstrosity, surpassing even the celebrated dwarf twisted shrubs of Japanese horticulturists. Such varieties however, do not exist at present. The ordinary twisted races on the other hand, are found in the wild state and have only to be isolated and cultivated to yield large numbers [447] of twisted individuals. In nature they are able to maintain themselves during long centuries, quite as well as normal species and varieties. But they owe this quality entirely to their dimorphous character. A twisted race of teasels might consist of successive generations of tall atavistic individuals, and produce yearly some twisted specimens, which might be destroyed every time before ripening their seeds. Reasoning from the evidence available, and from analogous cases, the variety would, even under such extreme circumstances, be able to last as long as any other good variety or elementary species. And it seems to me that this explanation makes clear how it is possible that varieties, which are potentially rich in their peculiar monstrosity, are discovered from time to time among plants when tested by experimental methods. Granting these conclusions, monstrosities on the one side, and dimorphous wild species on the other, constitute the most striking examples of the inheritance of latent characters. The bearing of the phenomena of dimorphism upon the principles of evolution formulated by Lamarck, and modified by his followers to constitute Neo-Lamarckianism, remains to be considered. Lamarck assumed that the external conditions directly affected the organisms in [448] such a way as to make them better adapted to life, under prevailing circumstances. Nageli gave to this conception the name "Theory of direct causation" (Theorie der directen Bewirkung), and it has received the approval of Von Wettstein, Strasburger and other German investigators. According to this conception a plant, when migrating from lowlands into the mountains would slowly be changed and gradually assume alpine habits. Once acquired this habit would become fixed and attain the rank of specific characters. In testing this theory by field-observations and culture-experiments, the defenders of the Nagelian principle could easily produce evidence upon the first point. The change of lowland-plants into alpine varieties can be brought about in numerous cases, and corresponding changes under the influence of soil, or climate, or life-conditions are on record for the most various characters and qualities. The second point, however, is as difficult to prove as the first is of easy treatment. If after hundreds and thousands of years of exposure to alpine or other extreme conditions a fixed change is proved to have taken place, the question remains unanswered, whether the change has been a gradual or a sudden one. Darwin pointed out that long periods of life afford a [449] chance for a sudden change in the desired direction, as well as for the slow accumulation of slight deviations. Any mutations in a wrong direction would at once be destroyed, but an accidental change in a useful way would be preserved, and multiply itself. If in the course of centuries this occurred, they would be nearly sure to become established, however rare at the outset. Hence the positive assertion is scarcely capable of direct proof. On the other hand the negative assertion must be granted full significance. If the alpine climate has done no more than produce a transitory change, it is clear that thousands of years do not, necessarily, cause constant and specific alterations. This requirement is one of the indispensable supports of the Lamarckian theory. The matter is capable of disproof however, and such disproof seems to be afforded by the direct evidence of the present condition of the alpine varieties at large, and by many other similar cases. Among these the observations of Holtermann on some desert-plants of Ceylon are of the highest value. Moreover they touch questions which are of wide importance for the study of the biology of American deserts. For this reason I may be allowed to introduce them here at some length. [450] The desert of Kaits, in Northern Ceylon, nourishes on its dry and torrid sands some species, represented by a large number of individuals, together with some rarer plants. The commonest forms are _Erigeron Asteroides_, _Vernonia cinerea_, _Laurea pinnatifida_, _Vicoa auriculata_, _Heylandia latebrosa_ and _Chrysopogon montanus_. In direct contrast with the ordinary desert-types they have a thin epidermis, with exposed stomata, features that ordinarily were characteristic of species of moister regions. They are annuals, growing rapidly, blooming and ripening their seeds before the height of the dry season. Evidently they are to be considered as the remainder of the flora of a previous period, when the soil had not yet become arid. They might be called relics. Of course they are small and dwarf-like, when compared with allied forms. These curious little desert-plants disprove the Nagelian views in two important points. First, they show that extreme conditions do not necessarily change the organisms subjected to them, in a desirable direction. During the many centuries that these plants must have existed in the desert in annual generations, no single feature in the anatomical structure has become changed. Hence the conclusion that small leaves, abundant rootstocks and short [451] stems, a dense foliage, a strongly cuticularized epidermis, few and narrow air-cavities in the tissues and all the long range of characteristics of typical desert-plants are not a simple result of the influence of climate and soil. There is no direct influence in this sense. The second point, in which Nageli's idea is broken down by Holtermann's observations, results from the behavior of the plants of the Kaits desert when grown or sown on garden soil. When treated in this way they at once lose the only peculiarity which might be considered as a consequence of the desert-life of their ancestors, their dwarf stature. They behave exactly like the alpine plants in Bonnier's experiments, and with even more striking differences. In the desert they attain a height of a few centimeters, but in the garden they attain half a meter and more in height. Nothing in the way of stability has resulted from the action of the dry soil, not even in such a minor point as the height of the stems. From the facts and discussions we may conclude that double adaptation is not induced by external influences, at least not in any way in which it might be of use to the plant. It may arise by some unknown cause, or may not be incited at all. In the first case the plant becomes capable of living under the alternating [452] circumstances, and if growing near the limits of such regions it will overlap and get into the new area. All other species, which did not acquire the double habit, are of course excluded, with such curious exceptions as those of Kaits. The typical vegetation under such extreme conditions however, finds explanation quite as well by the one as by the other view. Leaving these obvious cases of double adaptation, there still remains one point to be considered. It is the dwarf stature of so many desert and alpine plants. Are these dwarfs only the extremes of the normal fluctuating variability, or is their stature to be regarded as the expression of some peculiar adaptive but latent quality? It is as yet difficult to decide this question, because statistical studies of this form of variability are still wanting. The capacity of ripening the seed on individuals of dwarf stature however, is not at all a universal accompaniment of a variable height. Hence it cannot be considered as a necessary consequence of it. On the other hand the dwarf varieties of numerous garden-plants, as for instance: of larkspurs, snapdragon, opium-poppies and others are quite stable and thence are obviously due to peculiar characteristics. Such characteristics, if combined with tall stature into a pair of antagonists, would yield a double [453] adaptation, and on such a base a hypothetical explanation could no doubt be rested. Instead of discussing this problem from the theoretical side, I prefer to compare those species which are capable of assuming a dwarf stature under less uncommon conditions than those of alpine and desert-plants. Many weeds of our gardens and many wild species have this capacity. They become very tall, with large leaves, richly branched stems and numerous flowers in moist and rich soil. On bad soil, or if germinating too late, when the season is drier, they remain very small, producing only a few leaves and often limiting themselves to one flower-head. This is often seen with thorn-apples and amaranths, and even with oats and rye, and is notoriously the case with buckwheat. Gauchery has observed that the extremes differ often as much from one another as 1:10. In the case of the Canadian horseweed or _Erigeron canadensis_, which is widely naturalized in Europe, the tallest specimens are often twenty-five times as tall as the smallest, the difference increasing to greater extremes, if besides the main stem, the length of the numerous branches of the tall plants are taken into consideration. Other instances studied by the French investigator are _Erythraea pulchella_ and _Calamintha Acinos_. [454] Dimorphism is of universal occurrence in the whole vegetable kingdom. In some cases it is typical, and may easily be discerned from extreme fluctuating variability. In others the contrast is not at all obvious, and a closer investigation is needed to decide between the two possibilities. Sometimes the adaptive quality is evident, in other cases it is not. A large number of plants bear two kinds of leaves linked with one another by intermediate forms. Often the first leaves of a shoot, or those of accidentally strong shoots, exhibit deviating shapes, and the usefulness of such occurrences seems to be quite doubtful. The elongation of stems and linear leaves, and the reduction of lateral organs in darkness, is manifestly an adaptation. Many plants have stolons with double adaptations which enable them to retain their character of underground stems with bracts or to exchange it for the characteristics of erect stems with green leaves according to the outer circumstances. In some shrubs and trees the capacity of a number of buds to produce either flowers or shoots with leaves seems to be in the same condition. The capacity of producing spines is also a double adaptation, active on dry and arid soil and latent in a moist climate or under cultivation, as with the wild and cultivated apple, and in the experiments of Lothelier [455] with _Berberis_, _Lycium_ and other species, which lose their spines in damp air. In some conifers the evolution of horizontal branches may be modified by simply turning the buds upside down. Or the lateral branches can be induced to become erect stems by cutting off the normal summit of a tree. Numerous organs and functions lie dormant until aroused by external agencies, and many other cases could be cited, showing the wide occurrence of double adaptation. There are, however, two points, which should not be passed over without some mention. One of them is the influence of sun and shade on leaves, and the other the atavistic forms, often exhibited during the juvenile period. The leaves of many plants, and especially those of some shrubs and trees, have the capacity of adapting themselves either to intense or to diffuse light. On the circumference of the crown of a tree the light is stronger and the leaves a small and thick, with a dense tissue. In the inner parts of the crown the light is weak and the leaves are broader in order to get as much of it as possible. They become larger but thinner, consisting often of a small number of cell layers. The definitive formation is made in extreme youth, often even during the previous summer, at the time of the [456] very first evolution of the young organs within the buds. _Iris_, and _Lactuca Scariola_ or the prickly lettuce, and many other plants afford similar instances. As the definitive decision must be made in these cases long before the direct influence of the conditions which would make the change useful is felt, it is hardly conceivable how they could be ascribed to this cause. It is universally known that many plants show deviating features when very young, and that these often remind us of the characters of their probable ancestors. Many plants that must have been derived from their nearest systematic relatives, chiefly by reductions, are constantly betraying this relation by a repetition of the ancestral marks during their youth. There can be hardly a doubt that the general law of natural selection prevails in such cases as it does in others. Or stated otherwise, it is very probable, that in most cases the atavistic characters have been retained during youth because of their temporary usefulness. Unfortunately, our knowledge of utility of qualities is as yet, very incomplete. Here we must assume that what is ordinarily spared by natural selection is to be considered as useful, [457] until direct experimental investigations have been made. So it is for instance with the submerged leaves of water-plants. As a rule they are linear, or if compound, are reduced to densely branching filiform threads. Hence we may conclude that this structure is of some use to them. Now two European and some corresponding American species of water-parsnip, the _Sium latifolium_ and _Berula angustifolia_ with their allies, are umbellifers, which bear pinnate instead of bi- or tri-pinnate leaves. But the young plants and even the young shoots when developing from the rootstocks under water comply with the above rule, producing very compound, finely and pectinately dissected leaves. From a systematic point of view these leaves indicate the origin of the water-parsnips from ordinary umbellifers, which generally have bi- and tripinnate leaves. Similar cases of double adaptation, dependent on external conditions at different periods of the evolution of the plant are very numerous. They are most marked among leguminous plants, as shown by the trifoliolate leaves of the thorn-broom and allies, which in the adult state have green twigs destitute of leaves. As an additional instance of dimorphism and probable double adaptation to unrecognized external [458] conditions I might point to the genus _Acacia_. As we have seen in a previous lecture some of the numerous species of this genus bear bi-pinnate leaves, while others have only flattened leaf-stalks. According to the prevailing systematic conceptions, the last must have been derived from the first by the loss of the blades and the corresponding increase of size and superficial extension of the stalk. In proof of this view they exhibit, as we have described, the ancestral characters in the young plantlets, and this production of bi-pinnate leaves has probably been retained at the period of the corresponding negative mutations, because of some distinct, though still unknown use. Summarizing the results of this discussion, we may state that useful dimorphism, or double adaptation, is a substitution of characters quite analogous to the useless dimorphism of cultivated ever-sporting varieties and the stray occurrence of hereditary monstrosities. The same laws and conditions prevail in both cases. [459] E. MUTATIONS LECTURE XVI THE ORIGIN OF THE PELORIC TOAD-FLAX I have tried to show previously that species, in the ordinary sense of the word, consist of distinct groups of units. In systematic works these groups are all designated by the name of varieties, but it is usually granted that the units of the system are not always of the same value. Hence we have distinguished between elementary species and varieties proper. The first are combined into species whose common original type is now lost or unknown, and from their characters is derived an hypothetical image of what the common ancestor is supposed to have been. The varieties proper are derived in most cases from still existing types, and therefore are subjoined to them. A closer investigation has shown that this derivation is ordinarily produced by the loss of some definite attribute, or by the re-acquisition of an apparently [460] lost character. The elementary species, on the other hand, must have arisen by the production of new qualities, each new acquisition constituting the origin of a new elementary form. Moreover we have seen, that such improvements and such losses constitute sharp limits between the single unit-forms. Every type, of course, varies around an average, and the extremes of one form may sometimes reach or even overlap those of the nearest allies, but the offspring of the extremes always return to the type. The transgression is only temporary and a real transition of one form to another does not come within ordinary features of fluctuating variability. Even in the cases of eversporting varieties, where two opposite types are united within one race, and where the succeeding individuals are continually swinging from one extreme to the other, passing through a wide range of intermediate steps, the limits of the variety are as sharply defined and as free from real transgression as in any other form. In a complete systematic enumeration of the real units of nature, the elementary species and varieties are thus observed to be discontinuous and separated by definite gaps. Every unit may have its youth, may lead a long life in the adult state and may finally die. But through [461] the whole period of its existence it remains the same, at the end as sharply defined from its nearest allies as in the beginning. Should some of the units die out, the gaps between the neighboring ones will become wider, as must often have been the case. Such segregations, however important and useful for systematic distinctions, are evidently only of secondary value, when considering the real nature of the units themselves. We may now take up the other side of the problem. The question arises as to how species and varieties have originated. According to the Darwinian theory they have been produced from one another, the more highly differentiated ones from the simpler, in a graduated series from the most simple forms to the most complicated and most highly organized existing types. This evolution of course must have been regular and continuous, diverging from time to time into new directions, and linking all organisms together into one common pedigree. All lacunae in our present system are explained by Darwin as due to the extinction of the forms, which previously filled them. Since Lamarck first propounded the conception of a common origin for all living beings, much has been done to clear up our ideas as to the real nature of this process. The broader [462] aspect of the subject, including the general pedigree of the animal and vegetable kingdom, may be said to have been outlined by Darwin and his followers, but this phase of the subject lies beyond the limits of our present discussion. The other phase of the problem is concerned with the manner in which the single elementary species and varieties have sprung from one another. There is no reason to suppose that the world is reaching the end of its development, and so we are to infer that the production of new species and varieties is still going on. In reality, new forms are observed to originate from time to time, both wild and in cultivation, and such facts do not leave any doubt as to their origin from other allied types, and according to natural and general laws. In the wild state however, and even with cultivated plants of the field and garden, the conditions, though allowing of the immediate observation of the origination of new forms, are by no means favorable for a closer inquiry into the real nature of the process. Therefore I shall postpone the discussion of the facts till another lecture, as their bearing will be more easily understood after having dealt with more complete cases. These can only be obtained by direct experimentation. Comparative studies, of course, [463] are valuable for the elucidation of general problems and broad features of the whole pedigree, but the narrower and more practical question as to the genetic relation of the single forms to one another must be studied in another way, by direct experiment. The exact methods of the laboratory must be used, and in this case the garden is the laboratory. The cultures must be guarded with the strictest care and every precaution taken to exclude opportunities for error. The parents and grandparents and their offspring must be kept pure and under control, and all facts bearing upon the birth or origin of the new types should be carefully recorded. Two great difficulties have of late stood in the way of such experimental investigation. One of them is of a theoretical, the, other of a practical nature. One is the general belief in the supposed slowness of the process, the other is the choice of adequate material for experimental purposes. Darwin's hypothesis of natural selection as the means by which new types arise, is now being generally interpreted as stating the slow transformation of ordinary fluctuating divergencies from the average type into specific differences. But in doing so it is overlooked that Quetelet's law of fluctuating variability was not yet discovered at the time, when Darwin propounded his theory. So there [464] is no real and intimate connection between these two great conceptions. Darwin frequently pointed out that a long period of time might be needed for slow improvements, and was also a condition for the occurrence of rare sports. In any case those writers have been in error, according to my opinion, who have refrained from experimental work on the origin of species, on account of this narrow interpretation of Darwin's views. The choice of the material is quite another question, and obviously all depends upon this choice. Promising instances must be sought for, but as a rule the best way is to test as many plants as possible. Many of them may show nothing of interest, but some might lead to the desired end. For to-day's lecture I have chosen an instance, in which the grounds upon which the choice was based are very evident. It is the origin of the peloric toad-flax (_Linaria vulgaris peloria_). The ground for this choice lies simply in the fact that the peloric toad-flax is known to have originated from the ordinary type at different times and in different countries, under more or less divergent conditions. It had arisen from time to time, and hence I presumed that there was a chance to see it arise again. If this should happen under experimental circumstances [465] the desired evidence might easily be gathered. Or, to put it in other words, we must try to arrange things so as to be present at the time when nature produces another of these rare changes. There was still another reason for choosing this plant for observational work. The step from the ordinary toad-flax to the peloric form is short, and it appears as if it might be produced by slow conversion. The ordinary species produces from time to time stray peloric flowers. These occur at the base of the raceme, or rarely in the midst of it. In other species they are often seen at the summit. Terminal pelories are usually regular, having five equal spurs. Lateral pelories are generally of zygomorphic structure, though of course in a less degree than the normal bilabiate flowers, but they have unequal spurs, the middle one being of the ordinary length, the two neighboring being shorter, and those standing next to the opposite side of the flower being the shortest of all. This curious remainder of the original, symmetrical structure of the flower seems to have been overlooked hitherto by the investigators of peloric toad-flaxes. The peloric variety of this plant is characterized by its producing only peloric flowers. No single bilabiate or one-spurred flower remains. [466] I once had a lot of nearly a hundred specimens of this fine variety, and it was a most curious and beautiful sight to observe the many thousands of nearly regular flowers blooming at the same time. Some degree of variability was of course present, even in a large measure. The number of the spurs varied between four and six, transgressing these limits in some instances, but never so far as to produce really one-spurred flowers. Comparing this variety with the ordinary type, two ways of passing over from the one to the other might be imagined. One would entail a slow increase of the number of the peloric flowers on each plant, combined with a decrease of the number of the normal ones, the other a sudden leap from one extreme to the other without any intermediate steps. The latter might easily be overlooked in field observations and their failure may not have the value of direct proof. They could never be overlooked, on the other hand, in experimental culture. The first record of the peloric toad-flax is that of Zioberg, a student of Linnaeus, who found it in the neighborhood of Upsala. This curious discovery was described by Rudberg in his dissertation in the year 1744. Soon afterwards other localities were discovered by Link near Gottingen in Germany about 1791 and afterwards [467] in the vicinity of Berlin, as stated by Ratzeburg, 1825. Many other localities have since been indicated for it in Europe, and in my own country some have been noted of late, as for instance near Zandvoort in 1874 and near Oldenzaal in 1896. In both these last named cases the peloric form arose spontaneously in places which had often been visited by botanists before the recorded appearance, and therefore, without any doubt, they must have been produced directly and independently by the ordinary species which grows in the locality. The same holds good for other occurrences of it. In many instances the variety has been recorded to disappear after a certain lapse of time, the original specimens dying out and no new ones being produced. _Linaria_ is a perennial herb, multiplying itself easily by buds growing on the roots, but even with this means of propagation its duration seems to have definite limits. There is one other important point arguing strongly for the independent appearance of the peloric form in its several localities. It is the difficulty of fertilization and the high degree of sterility, even if artificially pollinated. Bees and bumble-bees are unable to crawl into the narrow tubular flowers, and to bring the fertilizing pollen to the stigma. Ripe capsules with seeds [468] have never been seen in the wild state. The only writer who succeeded in sowing seeds of the peloric variety was Wildenow and he got only very few seedlings. But even in artificial pollination the result is the same, the anthers seeming to be seriously affected by the change. I tried both self-fertilization and cross-pollination, and only with utmost care did I succeed in saving barely a hundred seeds. In order to obtain them I was compelled to operate on more than a thousand flowers on about a dozen peloric plants. The variety being wholly barren in nature, the assumption that the plants in the different recorded localities might have a common origin is at once excluded. There must have been at least nearly as many mutations as localities. This strengthens the hope of seeing such a mutation happen in one's own garden. It should also be remembered that peloric flowers are known to have originated in quite a number of different species of _Linaria_, and also with many of the allied species within the range of the Labiatiflorae. I will now give the description of my own experiment. Of course this did not give the expected result in the first year. On the contrary, it was only after eight years' work that I had the good fortune of observing the mutation. [469] But as the whole life-history of the preceding generations had been carefully observed and recorded, the exact interpretation of the fact was readily made. My culture commenced in the year 1886. I chose some plants of the normal type with one or two peloric flowers besides the bilabiate majority which I found on a locality in the neighborhood of Hilversum in Holland. I planted the roots in my garden and from them had the first flowering generation in the following summer. From their seeds I grew the second generation in three following years. They flowered profusely and produced in 1889 only one, and in 1890 only two peloric structures. I saved the seeds in 1889 and had in 1890-1891 the third generation. These plants likewise flowered only in the second year, and gave among some thousands of symmetrical blossoms, only one five-spurred flower. I pollinated this flower myself, and it produced abundant fruit with enough seeds for the entire culture in 1892, and they only were sown. Until this year my generations required two years each, owing to the perennial habit of the plants. In this way the prospects of the culture began to decrease, and I proposed to try to heighten my chances by having a new generation yearly. With this intention I sowed the [470] selected seeds in a pan in the glasshouse of my laboratory and planted them out as soon as the young stems had reached a length of some few centimeters. Each seedling was put in a separate pot, in heavily manured soil. The pots were kept under glass until the beginning of June, and the young plants produced during this period a number of secondary stems from the curious hypocotylous buds which are so characteristic of the species. These stems grew rapidly and as soon as they were strong enough, the plants were put into the beds. They all, at least nearly all, some twenty specimens, flowered in the following month. I observed only one peloric flower among the large number present. I took the plant bearing this flower and one more for the culture of the following year, and destroyed all others. These two plants grew on the same spot, and were allowed to fertilize each other by the agency of the bees, but were kept isolated from any other congener. They flowered abundantly, but produced only one-spurred bilabiate flowers during the whole summer. They matured more than 10 cu. cm. of seeds. It is from this pair of plants that my peloric race has sprung. And as they are the ancestors of the first closely observed case of peloric mutation, [471] it seems worth while to give some details regarding their fertilization. Isolated plants of _Linaria vulgaris_ do not produce seed, even if freely pollinated by bees. Pollen from other plants is required. This requirement is not at all restricted to the genus _Linaria_, as many instances are known to occur in different families. It is generally assumed that the pollen of any other individual of the same species is capable of producing fertilization, although it is to be said that a critical examination has been made in but few instances. This, however, is not the case, at least not in the present instance. I have pollinated a number of plants, grown from seed of the same strain and combined them in pairs, and excluded the visits of insects, and pollen other than that of the plant itself and that of the specimen with which it was paired. The result was that some pairs were fertile and others barren. Counting these two groups of pairs, I found them nearly equal in number, indicating thereby that for any given individual the pollen of half of the others is potent, but that of the other half impotent. From these facts we may conclude the presence of a curious case of dimorphy, analogous to that proposed for the primroses, but without visible differentiating marks in the flowers. At least such opposite characters [472] have as yet not been ascertained in the case of our toad-flax. In order to save seed from isolated plants it is necessary, for this reason, to have at least two individuals, and these must belong to the two physiologically different types. Now in the year 1892, as in other years, my plants, though separated at the outset by distances of about 20 cm. from each other, threw out roots of far greater length, growing in such a way as to abolish the strict isolation of the individuals. Any plot may produce several stems from such roots, and it is manifestly impossible to decide whether they all belong to one original plant or to the mixed roots of several individuals. No other strains were grown on the same bed with my plants however, and so I considered all the stems of the little group as belonging to one plant. But their perfect fertility showed, according to the experience described, that there must have been at least two specimens mingled together. Returning now to the seeds of this pair of plants, I had, of course, not the least occasion to ascribe to it any higher value than the harvest of former years. The consequence was that I had no reason to make large sowings, and grew only enough young plants to have about 50 in bloom in the summer of 1894. Among [473] these, stray peloric flowers were observed in somewhat larger number than in the previous generations, 11 plants bearing one or two, or even three such abnormalities. This however, could not be considered as a real advance, since such plants may occur in varying, though ordinarily small numbers in every generation. Besides them a single plant was seen to bear only peloric flowers; it produced racemes on several stems and their branches. All were peloric without exception. I kept it through the winter, taking care to preserve a complete isolation of its roots. The other plants were wholly destroyed. Such annihilation must include both the stems and roots and the latter of course requires considerable labor. The following year, however, gave proof of the success of the operation, since my plant bloomed luxuriously for the second time and remained true to the type of the first year, producing peloric flowers exclusively. Here we have the first experimental mutation of a normal into a peloric race. Two facts were clear and simple. The ancestry was known for over a period of four generations, living under the ordinary care and conditions of an experimental garden, isolated from other toad-flaxes, but freely fertilized by bees or at times by myself. This ancestry was quite constant as to [474] the peloric peculiarity, remaining true to the wild type as it occurs everywhere in my country, and showing in no respect any tendency to the production of a new variety. The mutation took place at once. It was a sudden leap from the normal plants with very rare peloric flowers to a type exclusively peloric. No intermediate steps were observed. The parents themselves had borne thousands of flowers during two summers, and these were inspected nearly every day, in the hope of finding some pelories and of saving their seed separately. Only one such flower was seen. If there had been more, say a few in every hundred flowers, it might be allowable to consider them as previous stages, showing a preparation of the impending change. But nothing of this kind was observed. There was simply no visible preparation for the sudden leap. This leap, on the other hand, was full and complete. No reminiscence of the former condition remained. Not a single flower on the mutated plant reverted to the previous type. All were thoroughly affected by the new attribute, and showed the abnormally augmented number of spurs, the tubular structure of the corolla and the round and narrow entrance of its throat. The whole plant departed absolutely from the old type of its progenitors. [475] Three ways were open to continue my experiment. The first was indicated by the abundant harvest from the parent-plants of the mutation. It seemed possible to compare the numerical proportion of the mutated seeds with those of normal plants. In order to ascertain this proportion I sowed the greatest part of my 10 cu. cm. of seed and planted some 2,000 young plants in little pots with well-manured soil. I got some 1,750 flowering plants and observed among them 16 wholly peloric individuals. The numerical proportion of the mutation was therefore in this instance to be calculated equal to about 1% of the whole crop. This figure is of some importance. For it shows that the chance of finding mutations requires the cultivation of large groups of individuals. One plant in each hundred may mutate, and cultures of less than a hundred specimens must therefore be entirely dependent on chance for the appearance of new forms, even if such should accidentally have been produced and lay dormant in the seed. In other cases mutations may be more numerous, or on the contrary, more rare. But the chance of mutative changes in larger numbers is manifestly much reduced by this experiment, and they may be expected to form a very small proportion of the culture. [476] The second question which arose from the above result was this. Could the mutation be repeated? Was it to be ascribed to some latent cause which might be operative more than once? Was there some hidden tendency to mutation, which, ordinarily weak, was strengthened in my cultures by some unknown influence? Was the observed mutation to be explained by a common cause with the other cases recorded by field-observations? To answer this question I had only to continue my experiment, excluding the mutated individuals from any intercrossing with their brethren. To this end I saved the seeds from duly isolated groups in different years and sowed them at different times. For various causes I was not prepared to have large cultures from these seeds, but notwithstanding this, the mutation repeated itself. In one instance I obtained two, in another, one peloric plant with exclusively many-spurred flowers. As is easily understood, these were related as "nieces" to the first observed mutants. They originated in quite the same way, by a sudden leap, without any preparation and without any intermediate steps. Mutation is proved by this experience to be of an iterative nature. It is the expression of some concealed condition, or as it is generally [477] called, of some hidden tendency. The real nature of this state of the hereditary qualities is as yet wholly unknown. It would not be safe to formulate further conclusions before the evidence offered by the evening-primroses is considered. Thirdly, the question arises, whether the mutation is complete, not only as to the morphologic character, but also as to the hereditary constitution of the mutated individuals. But here unfortunately the high degree of sterility of the peloric plants, as previously noted, makes the experimental evidence a thing of great difficulty. During the course of several years I isolated and planted together the peloric individuals already mentioned, all in all some twenty plants. Each individual was nearly absolutely sterile when treated with its own pollen, and the aid of insects was of no avail. I intercrossed my plants artificially, and pollinated more than a thousand flowers. Not a single one gave a normal fruit, but some small and nearly rudimentary capsules were produced, bearing a few seeds. From these I had 119 flowering plants, out of which 106 were peloric and 13 one-spurred. The great majority, some 90%, were thus shown to be true to their new type. Whether the 10% reverting ones were truly atavists, or whether they were [478] only vicinists, caused by stray pollen grains from another culture, cannot of course be decided with sufficient certitude. Here I might refer to the observations concerning the invisible dimorphous state of the flowers of the normal toad-flax. Individuals of the same type, when fertilized with each other, are nearly, but not absolutely, sterile. The yield of seeds of my peloric plants agrees fairly well with the harvest which I have obtained from some of the nearly sterile pairs of individuals in my former trial. Hence the suggestion is forced upon us that perhaps, owing to some unknown cause, all the peloric individuals of my experiment belonged to one and the same type, and were sterile for this reason only. If this is true, then it is to be presumed that all previous investigators have met the same condition, each having at hand only one of the two required types. And this discussion has the further advantage of showing the way, in which perhaps a full and constant race of peloric toad-flaxes may be obtained. Two individuals of different type are required to start from. They seem as yet never to have arisen from one group of mutations. But if it were possible to combine the products of two mutations obtained in different countries and under different conditions, there would be a chance [479] that they might belong to the supposed opposite types, and thus be fertile with one another. My peloric plants are still available, and the occurrence of this form elsewhere would give material for a successful experiment. The probability thereof is enhanced by the experience that my peloric plants bear large capsules and a rich harvest of seeds when fertilized from plants of the normal one-spurred race, while they remain nearly wholly barren by artificial fertilization with others. I suppose that they are infertile with the normal toad-flaxes of their own sexual disposition, but fertile with those of the opposite constitution. At all events the fact that they may bear abundant seed when properly pollinated is an indication of successful experiments on the possibility of gaining a hereditary race with exclusively peloric flowers. And such a race would be a distinct gain for sundry physiologic inquiries, and perhaps not wholly destitute of value from an horticultural point of view. Returning now to the often recorded occurrence of peloric toad-flaxes in the wild state and recalling our discussion about the improbability of a dispersion from one locality to another by seed, and the probability of independent origin for most of these cases, we are confronted with the conception that a latent [480] tendency to mutation must be universally present in the whole species. Another observation, although it is of a negative character, gains in importance from this point of view. I refer to the total lack of intermediate steps between normal and peloric individuals. If such links had ordinarily been produced previous to the purely peloric state they would no doubt have been observed from time to time. This is so much the more probable as _Linaria_ is a perennial herb, and the ancestors of a mutation might still be in a flowering condition together with their divergent offspring. But no such intermediates are on record. The peloric toad-flaxes are, as a rule, found surrounded by the normal type, but without intergrading forms. This discontinuity has already been insisted upon by Hofmeister and others, even at the time when the theory of descent was most under discussion, and any link would surely have been produced as a proof of a slow and continuous change. But no such proof has been found, and the conclusion seems admissible that the mutation of toad-flaxes ordinarily, if not universally, takes place by a sudden step. Our experiment may simply be considered as a thoroughly controlled instance of an often recurring phenomenon. It teaches us how, in the [481] main, the peloric mutations must be assumed to proceed. This conception may still be broadened. We may include in it all similar occurrences, in allied and other species. There is hardly a limit to the possibilities which are opened up by this experience. But it will be well to refrain from hazardous theorizing, and consider only those cases which may be regarded as exact repetitions of the same phenomenon and of which our culture is one of the most recent instances on record. We will limit ourselves to the probable origin of peloric variations at large, of which little is known, but some evidence may be derived from the recorded facts. Only one case can be said to be directly analogous to our observations. This refers to the peloric race of the common snapdragon, or _Antirrhinum majus_ of our gardens. It is known to produce peloric races from time to time in the same way as does the toadflax. But the snapdragon is self-fertile and so is its peloric variety. Some cases are relatively old, and some of them have been recorded and in part observed by Darwin. Whence they have sprung and in what manner they were produced, seems never to have been noted. Others are of later origin, and among these one or two varieties have been accidentally produced [482] in the nursery of Mr. Chr. Lorenz in Erfurt, and are now for sale, the seeds being guaranteed to yield a large proportion of peloric individuals. The peloric form in this case appeared at once, but was not isolated, and was left free to visiting insects, which of course crossed it with the surrounding varieties. Without doubt the existence of two color-varieties of the peloric type, one of a very dark red, indicating the "Black prince" variety as the pollen-parent, and the other with a white tube of the corolla, recalling the form known as "Delila," is due to these crossings. I had last year (1903) a large lot of plants, partly normal and partly peloric, but evidently of hybrid origin, from seeds from this nursery, showing moreover all intermediate steps between nearly wholly peloric individuals and apparently normal ones. I have saved the seeds of the isolated types and before seeing the flowers of their offspring, nothing can be said about the purity and constancy of the type, when freed from hybrid admixtures. The peloric snapdragon has five small unequal spurs at the base of its long tube, and in this respect agrees with the peloric toad-flax. Other pelories are terminal and quite regular, and occur in some species of _Linaria_, where I observed them in _Linaria dalmatica_. The [483] terminal flowers of many branches were large and beautifully peloric, bearing five long and equal spurs. About their origin and inheritance nothing is known. A most curious terminal pelory is that of the common foxglove or _Digitalis purpurea_. As we have seen in a previous lecture, it is an old variety. It was described and figured for the first time by Vrolik of Amsterdam, and the original specimens of his plates are still to be seen in the collections of the botanic garden of that university. Since his time it has been propagated by seed as a commercial variety, and may be easily obtained. The terminal flower of the central stem and those of the branches only are affected, all other flowers being wholly normal. Almost always it is accompanied by other deviations, among which a marked increase of the number of the parts of the corolla and other whorls is the most striking. Likewise supernumerary petals on the outer side of the corolla, and a production of a bud in the center of the capsule may be often met with. This bud as a rule grows out after the fading away of the flower, bursting through the green carpels of the unripe fruit, and producing ordinarily a secondary raceme of flowers. This raceme is a weak but exact repetition of the first, bearing symmetrical foxgloves all [484] along and terminating in a peloric structure. On the branches these anomalies are more or less reduced, according to the strength of the branch, and conforming to the rule of periodicity, given in our lecture on the "five-leaved" clover. Through all this diminution the peloric type remains unchanged and therefore becomes so much the purer, the weaker the branches on which it stands. I am not sure whether such peloric flowers have ever been purely pollinated and their seed saved separately, but I have often observed that the race comes pure from the seed of the zygomorphic flowers. It is as yet doubtful whether it is a half race or a double race, and whether it might be purified and strengthened by artificial selection. Perhaps the determination of the hereditary percentage described when dealing with the tricotyls might give the clue to the acquisition of a higher specialized race. The variety is old and widely disseminated, but must be subjected to quite a number of additional experiments before it can be said to be sufficiently understood. The most widespread peloric variety is that of _Gloxinia_. It has erect instead of drooping flowers; and with the changed position the structure is also changed. Like other pelories it has five equal stamens instead of four unequal [485] ones, and a corolla with five equal segments instead of an upper and a lower lip. It shows the peloric condition in all of its flowers and is often combined with a small increase of the number of the parts of the whorls. It is for sale under the name of _erecta_, and may be had in a wide range of color-types. It seems to be quite constant from seed. Many other instances of peloric flowers are on record. Indian cress or _Tropaeolum majus_ loses the spur in some double varieties and with it most of its symmetrical structure; it seems to be considered justly as a peloric malformation. Other species produce such anomalies only from time to time and nothing is known about their hereditary tendency. One of the most curious instances is the terminal flower of the raceme of the common laburnum, which loses its whole papilionaceous character and becomes as regularly quinate as a common buttercup. Some families are more liable to pelorism than others. Obviously all the groups, the flowers of which are not symmetrical, are to be excluded. But then we find that labiates and their allies among the dicotyledonous plants, and orchids among the monocotyledonous ones are especially subjected to this alteration. In both groups many genera and a long list of species [486] could be quoted as proof. The family of the labiates seems to be essentially rich in terminal pelories, as for instance in the wild sage or _Salvia_ and the dead-nettle or _Lamium_. Here the pelories have long and straight corolla-tubes, which are terminated by a whorl of four or five segments. Such forms often occur in the wild state and seem to have a geographic distribution as narrowly circumscribed as in the case of many small species. Those of the labiates chiefly belong to southern Europe and are unknown at least in some parts of the other countries. On the contrary terminal pelories of _Scrophularia nodosa_ are met with from time to time in Holland. Such facts clearly point to a common origin, and as only the terminal flowers are affected by the malformation, the fertility of the whole plant is evidently not seriously infringed upon. Before leaving the labiates, we may cite a curious instance of pelorism in the toad-flax, which is quite different from the ordinary peloric variety. This latter may be considered from a morphologic standpoint to be owing to a five-fold repetition of the middle part of the underlip. This conception would at once explain the occurrence of five spurs and of the orange border all around the corolla-tube. We might readily imagine that any other of the five [487] parts of the corolla could be repeated five-fold, in which case there would be no spur, and no orange hue on the upper corolla-ring. Such forms really occur, though they seem to be more rare than the five-spurred pelories. Very little is known about their frequency and hereditary qualities. Orchids include a large number of peloric monstrosities and moreover a wild pelory which is systematically described not only as a separate species but even as a new genus. It bears the name of _Uropedium lindenii_, and is so closely related to _Cypripedium caudatum_ that many authors take it for the peloric variety of this plant. It occurs in the wild state in some parts of Mexico, where the _Cypripedium_ also grows. Its claims to be a separate genus are lessened by the somewhat monstrous condition of the sexual organs, which are described as quite abnormal. But here also, intermediates are lacking, and this fact points to a sudden origin. Many cases of pelorism afford promising material for further studies of experimental mutations. The peloric toad-flax is only the prototype of what may be expected in other cases. No opportunity should be lost to increase the as yet too scanty, evidence on this point. [488] LECTURE XVII THE PRODUCTION OF DOUBLE FLOWERS Mutations occur as often among cultivated plants as among those in the wild state. Garden flowers are known to vary markedly. Much of their variability, however, is due to hybridism, and the combination of characters previously separate has a value for the breeder nearly equal the production of really new qualities. Nevertheless there is no doubt that some new characters appear from time to time. In a previous lecture we have seen that varietal characters have many features in common. One of them is their frequent recurrence both in the same and in other, often very distantly related, species. This recurrence is an important factor in the choice of the material for an experimental investigation of the nature of mutations. Some varieties are reputed to occur more often and more readily than others. White-colored varieties, though so very common, seem for the most part to be of ancient date, but only few [489] have a known origin, however. Without any doubt many of them have been found in a wild state and were introduced into culture. On the other hand double flowers are exceedingly rare in the wild state, and even a slight indication of a tendency towards doubling, the stray petaloid stamens, are only rarely observed growing wild. In cultivation, however, double flowers are of frequent occurrence; hence the conclusion that they have been produced in gardens and nurseries more frequently than perhaps any other type of variety. In the beginning of my experimental work I cherished the hope of being able to produce a white variety. My experiments, however, have not been successful, and so I have given them up temporarily. Much better chances for a new double variety seemed to exist, and my endeavors in this direction have finally been crowned with success. For this reason I propose to deal now with the production of double flowers, to inquire what is on record about them in horticultural literature, and to give a full description of the origin thereof in an instance which it was my good fortune to observe in my garden. Of course the historical part is only a hasty survey of the question and will only give such evidence as may enable us to get an idea of the [490] chances of success for the experimental worker. In the second half of the seventeenth century (1671), my countryman, Abraham Munting, published a large book on garden plants with many beautiful figures. It is called "Waare Oeffeninge der Planters," or "True Exercises With Plants." The descriptions pertain to ordinary typical species in greater part, but garden varieties receive special attention. Among these a long list of double flowers are to be seen. Double varieties of poppies, liverleaf (Hepatica), wallflowers (_Cheiranthus_), violets, _Caltha_, _Althaea_, _Colchicum_, and periwinkles (_Vinca_), and a great many other common flowers were already in cultivation at that time. Other double forms have been since added. Many have been introduced from Japan, especially the Japanese marigold, _Chrysanthemum indicum_. Others have been derived from Mexico, as for instance the double zinnias. The single dahlias only seem to have been originally known to the inhabitants of Mexico. They were introduced into Spain at about 1789, and the first double ones were produced in Louvain, Belgium, in 1814. The method of their origin has not been described, and probably escaped the originators themselves. But in historical records we find the curious statement that it took place after three years' work. This indicates [491] a distinct plan, and the possibility of carrying it to a practical conclusion within a few years' time. Something more is known about other cases. Garden anemones, _Anemone coronaria_, are said to have become double in the first half of the last century in an English nursery. The owner, Williamson, observing in his beds a flower with a single broadened stamen, saved its seeds separately, and in the next generations procured beautifully filled flowers. These he afterwards had crossed by bees with a number of colored varieties, and in this way succeeded in producing many new double types of anemone. The first double petunia is known to have suddenly and accidentally arisen from ordinary seed in a private garden at Lyons about 1855. From this one plant all double races and-varieties have been derived by natural and partly by artificial crosses. Carriere, who reported this fact, added that likewise other species were known at that time to produce new double varieties rapidly. The double fuchsias originated about the same time (1854) and ten years later the range of double varieties of this plant had become so large that Carriere found it impossible to enumerate all of them. Double carnations seem to be relatively old, double corn-flowers and double blue-bells being [492] of a later period. A long list could easily be made, to show that during the whole history of horticulture double varieties have arisen from time to time. As far as we can judge, such appearances have been isolated and sudden. Sometimes they sprang into existence in the full display of their beauty, but most commonly they showed themselves for the first time, exhibiting only spare supernumerary petals. Whenever such sports were worked up, a few years sufficed to reach the entire development of the new varietal attribute. From this superficial survey of historical facts, the inference is forced upon us that the chance of producing a new double variety is good enough to justify the attempt. It has frequently succeeded for practical purposes, why should it not succeed as well for purely scientific investigation? At all events the type recommends itself to the student of nature, both on account of its frequency, and of the apparent insignificance of the first step, combined with the possibility of rapidly working up from this small beginning of one superfluous petal towards the highest degree of duplication. Compared with the tedious experimental production of the peloric toad-flax, the attempt to produce a double flower has a distinct attraction. The peloric toad-flax is nothing new; the [493] experiment was only a repetition of what presumably takes place often within the same species. To attempt to produce a double variety we may choose any species, and of course should select one which as yet has not been known to produce double flowers. By doing so we will, if we succeed, produce something new. Of course, it does not matter whether the new variety has an horticultural interest or not, and it seems preferable to choose a wild or little cultivated species, to be quite sure that the variety in question is not already in existence. Finally the prospect of success seems to be enhanced if a species is chosen, the nearest allies of which are known to have produced double flowers. For these reasons and others I chose for my experiment the corn-marigold, or _Chrysanthemum segetum_. It is also called the golden cornflower. In the wheat and rye fields of central Europe it associates with the blue-bottle or blue corn-flower. It is sometimes cultivated and the seeds are offered for sale by many nurserymen. It has a cultivated variety, called _grandiflorum_, which is esteemed for its brilliancy and long succession of golden bloom. This variety has larger flower-heads, surrounded with a fuller border of ray-florets. The species belongs to a genus many species of which have produced [494] double varieties. One of them is the Japanese marigold, others are the _carinatum_ and the _imbricatum_ species. Nearly allied are quite a number of garden-plants with double flower-heads, among which are the double camomiles. My attention was first drawn to the structure of the heads and especially to the number of the ray-florets of the corn-marigold. The species appertains to that group of composites which have a head of small tubular florets surrounded by a broad border of rays. These rays, when counted, are observed to occur in definite numbers, which are connected with each other by a formula, known as "the series" of Braun and Schimper. In this formula, which commences with 1 and 2, each number is equal to the sum of the two foregoing figures. Thus 5, 8 and 13 are very frequent occurrences, and the following number, 21, is a most general one for apparently full rays, such as in daisies, camomiles, _Arnica_ and many other wild and cultivated species. These numbers are not at all constant. They are only the averages, around which the real numbers fluctuate. There may even be an overlapping of the extremes, since the fluctuation around 13 may even go beyond 8 and 21, and so on. But such extremes are only found in stray flowers, occurring on the same [495] individuals with the lesser degrees of deviation. Now the marigold averages 13, and the _grandiflorum_ 21 rays. The wild species is pure in this respect, but the garden-variety is not. The seeds which are offered for sale usually contain a mixture of both forms and their hybrids. So I had to isolate the pure types from this mixture and to ascertain their constancy and mutual independency. To this end I isolated from the mixture first the 13-rayed, and afterwards the 21-rayed types. As the marigolds are not sufficiently self-fertile, and are not easily pollinated artificially, it seemed impossible to carry on these two experiments at the same time and in the same garden. I devoted the first three years to the lower form, isolated some individuals with 12-13 rays out of the mixture of 1892 and counted the ray-florets on the terminal head of every plant of the ensuing generation next year. I cultivated and counted in this way above 150 individuals and found an average of exactly 13 with comparatively few individuals displaying 14 or only 12 rays, and with the remainder of the plants grouped symmetrically around this average. I continued the experiment for still another year and found the same group of figures. I was then satisfied as to the purity of the isolated strain. Next year I sowed a new mixture in [496] order to isolate the reputed pure _grandiflorum_ type. During the beginning of the flowering period I ruthlessly threw away all plants displaying less than 21 rays in the first or terminal head. But this selection was not to be considered as complete, because the 13-rayed race may eventually transgress its boundary and come over to the 21 and more. This made a second selection necessary. On the selected plants all the secondary heads were inspected and their ray-florets counted. Some individuals showed an average of about 13 and were destroyed. Others gave doubtful figures and were likewise eliminated, and only 6 out of a lot of nearly 300 flowering plants reached an average of 21 for all of the flowers. Our summer is a short one, compared with the long and beautiful summer of California, and it was too late to cut off the faded and the open flowers, and await new ones, which might be purely fertilized after the destruction of all minor plants. So I had to gather the seed from flowers, which might have been partially fertilized by the wrong pollen. This however, is not so great a drawback in selection experiments as might be supposed at first sight. The selection of the following year is sure to eliminate the offspring of such impure parentage. [497] A far more important principle is that of the hereditary percentage, already discussed in our lecture on the selection of monstrosities. In our present case it had to be applied only to the six selected plants of 1895. To this end the seeds of each of them were sown separately, the ray-florets of the terminal heads of each of the new generation were counted, and curves and averages were made up for the six groups. Five of them gave proof of still being mixtures and were wholly rejected. The children of the sixth parent, however, formed a group of uniform constitution, all fluctuating around the desired average of 21. All in all the terminal heads of over 1,500 plants have been subjected to the somewhat tedious work of counting their ray-florets. And this not in the laboratory, but in the garden, without cutting them off. Otherwise it would obviously have been impossible to recognize the best plants for preservation. I chose only two plants which in addition recommended themselves by the average number of rays on their secondary heads, sowed their seeds next year separately and compared the numerical constitution of their offspring. Both groups averaged 21 and were distributed very symmetrically around this mean. This result [498] showed that no further selection could be of any avail, and that I had succeeded in purifying the 21-rayed _grandiflorum_ variety. It is from this _grandiflorum_ that I have finally produced my double variety. In the year 1896 I selected from among the above quoted 1,500 plants, 500 with terminal heads bearing 21 or more rays. On these I counted the rays of all the secondary heads about the middle of August (1896) and found that they had, as a rule, retrograded to lower figures. On many thousands of heads only two were found having 22 rays. All others had the average number of 21 or even less. I isolated the individual which bore these two heads, allowed them to be fertilized by insects with the pollen of some of the best plants of the same group, but destroyed the remainder. This single exceptional plant has been the starting point of my double variety. It was not remarkable for its terminal head, which exhibited the average number of rays of the 21-rayed race. Nor was it distinguished by the average figure for all its heads. It was only selected because it was the one plant which had some secondary heads with one ray more than all the others. This indication was very slight, and could not have been detected save by the counting of the rays of thousands of heads. [499] But the rarity of the anomaly was exactly the indication wanted, and the same deviation would have had no signification whatever, had it occurred in a group fluctuating symmetrically around the average figure. On the other hand, the observed anomaly was only an indication, and no guarantee of future developments. Here it should be remarked that the indication alluded to was not the appearance of the expected character of doubling in ever so slight a measure. It was only a guide to be followed in further work. The real character of double flower-heads among composites lies in the production of rays on the disk. No increase of the number of the outer rays can have the same significance. A hasty inspection of double flower heads may convey the idea that all rays are arranged around a little central cluster of disk-florets, the remainder of the original disk-florets but a closer investigation will always reveal the fallacy of this conclusion. Hidden between the inner rays, and covered by them, lie the little tubular and fertile florets everywhere on the disk. They may not be easily seen, but if the supernumerary rays are pulled out, the disk may be seen to bear numerous small florets at intervals. But these intervals are not at all numerous, showing thereby that only a relatively small number of tubes has been [500] converted into rays. This conversion is obviously the true mark of the doubling, and before traces of it are found, no assertion whatever can be given as to the issue of the pedigree experiment. Three more years were required before this first, but decisive trace was discovered. During these years I subjected my strain to the same sharp selection as has already been described. The chosen ancestor of the race had flowered in 1896, and the next year I sowed its seeds only. From this generation I chose the one plant with the largest number of rays in its terminal head, and repeated this in the following year. The consequence was that the average number of rays increased rapidly, and with it the absolute maximum of the whole strain. The average came up from 21 to 34. Brighter and brighter crowns of the yellow rays improved my race, until it became difficult and very time consuming to count all the large rays of the borders. The largest numbers determined in the succeeding generations increased by leaps from 21 to 34 in the first year, and thence to 48 and 66 in the two succeeding summers. Every year I was able to save enough seed from the very best plant and to use it only for the continuance of the race. Before the selected plants were allowed to open the flowers from which the seed [501] was to be gathered, nearly the whole remaining culture was exterminated, excepting only some of the best examples, in order to have the required material for cross-pollination by insects. Each new generation was thereby as sharply selected as possible with regard to both parents. All flower-heads were of course closely inspected. Not the slightest indication of real doubling was discovered, even in the summer of 1899 in the fourth generation of my selected race. But among the best the new character suddenly made its appearance. It was at the commencement of September (1899), too late to admit of the seeds ripening before winter. An inspection of the younger heads was made, which revealed three heads with some few rays in the midst of the disk on one plant, the result of the efforts of four years. Had the germ of the mutation lain hidden through all this time? Had it been present, though dormant in the original sample of seed? Or had an entirely new creation taken place during my continuous endeavors? Perhaps as their more or less immediate result? It is obviously impossible to answer these questions, before further and similar experiments shall have been performed, bringing to light other details that will enable us to reach a more definite conclusion. [502] The fact that the origination of such forms is accessible to direct investigation is proven quite independently of all further considerations. The new variety came into existence at once. The leap may have been made by the ancestor of the year 1895, or by the plant of 1899, which showed the first central rays, or the sport may have been gradually built up during those four years. In each case there was a leap, contrasting with the view which claims a very long succession of years for the development of every new character. Having discovered this first trace of doubling, it was to be expected that the new variety would be at once as pure and as rich as other double composites usually are. Some effect of the crossing with the other seed-bearing individuals might still disturb this uniformity in the following year, but another year's work would eliminate even this source of impurity. These two years have given the expected result. The average number of the rays, which had already arisen from 13 to 34 now at once came up to 47 and 55, the last figure being the sum of 21 and 34 and therefore the probable uttermost limit to be reached before absolute doubling. The maximum numbers came as high as 100 in 1900, and reached even 200 in 1901. Such heads are as completely double as are the [503] brightest heads of the most beautiful double commercial varieties of composites. Even the best white camomiles (_Chrysanthemum inodorum_) and the gold-flowers or garden-marigolds (_Calendula officinalis_) do not come nearer to purity since they always have scores of little tubular florets between the rays on their disks. Real atavists or real reversionists were seen no more after the first purification of the race. I have continued my culture and secured last summer (1903) as many and as completely doubled heads as previously. The race has at once become permanent and constant. It has of course a wide range of fluctuating variability, but the lower limit has been worked up to about 34 rays, a figure never reached by the _grandiflorum_ parent, from which my new variety is thus sharply separated. Unfortunately the best flowers and even the best individuals of my race are wholly barren. Selection has reached its practical limit. Seeds must be saved from less dense heads, and no way has been found of avoiding it. The ray-florets are sterile, even in the wild species, and when growing in somewhat large numbers on the disk, they conceal the fertile flowers from the visiting insects, and cause them also to be sterile. The same is the case with the best cultivated forms. Their showiest individuals are [504] barren, and incapable of the reproduction of the race. This last is therefore, of necessity, always continued by means of individuals whose deviation from the mean average is the least. But in many cases the varieties are so highly differentiated that selection has become quite superfluous for practical purposes. I have already discussed the question as to the actual moment, in which the change of the _grandiflorum_ variety into the new _plenum_ form must be assumed to have taken place. In this respect some stress is to be laid on the fact that the improvement through selection has been gradual and continuous, though very rapid from the first moment. But with the appearance of the first stray rays within the disk, this continuity suddenly changed. All the children of this original mutated plant showed the new character, the rays within the disk, without exception. Not on all the heads, nor even on the majority of the heads on some individuals, but on some heads all gave clear proof of the possession of the new attribute. This was present in all the representatives of the new race, and had never been seen in any of their parents and grandparents. Here there was evidently a sudden leap, at least in the external form of the plants. And it seems to me to be the most simple conception, [505] that this visible leap directly corresponded to that inner change, which brought about the complete inheritability of the new peculiarity. It is very interesting to observe how completely my experience agrees with the results of the observations of breeders at large. No doubt a comparison is difficult, and the circumstances are not adequate to a close study. Isolation and selection have been applied commonly only so far as was consistent with the requirements of practical horticulture, and of course a determination of the hereditary percentage was never made. The disregard of this feature made necessary a greater length of time and a larger number of generations to bring about the desired changes. Notwithstanding this, however, it has been seen that double varieties are produced suddenly. This may have occurred unexpectedly or after a few years' effort toward the end desired. Whether this sudden appearance is the consequence of a single internal differentiating step, or of the rapid succession of lesser changes, cannot yet be made out. The extreme variability of double flowers and the chance of their appearance with only slight indications of the previous petaloid alterations of a few stamens may often result in their origin being overlooked, while subsequent generations may come in for full notice. [506] In the greater number of cases recorded it remains doubtful whether the work said to be done to obtain a new double variety was done before the appearance of these preliminary indications or afterward. In the first case, it would correspond with our selection of large numbers of florets in the outer rays, in the second however, with the ordinary purification of new races from hybrid mixtures. In scientific selection-experiments such crosses are of course avoided, and the process of purification is unnecessary, even as in the _Chrysanthemum_ culture. The first generation succeeding the original plant with disk-rays was in this respect wholly uniform and true to the new type. In practice the work does not start from such slight indications, and is done with no other purpose in view than to produce double flowers in species in which they did not already exist. Therefore it is of the highest importance to know the methods used and the chances of success. Unfortunately the evidence is very scanty on both points. Lindley and other writers, on horticultural theory and practice assert that a large amount of nourishment tends to produce double flowers, while a culture under normal conditions, [507] even if the plants are very strong and healthy, has no such effect. But even here it remains doubtful whether it applies to the period before or after the internal mutation. On the other hand success is not at all to be relied upon, nor is the work to be regarded as easy. The instances of double flowers said to be obtainable at will, are too rare in comparison with the number of cases, where the first indication of them was found accidentally. Leaving all these doubtful points, which will have to be cleared up by further scientific investigation, the high degree of variability requires further discussion. It may be considered from three different points of view according to the limit of the deviation from the average, to the dependency on external conditions and to periodicity. It seems best to take up the last two points first. On a visit to a nursery at Erfurt I once inspected an experiment with a new double variety of the common blue-bottle or blue corn-flower. The plants were dependent on the weather to a high degree. Bad weather increased the number of poorly filled flower-heads, while warm and sunny days were productive of beautiful double flowers. The heads that are borne by strong branches have a greater tendency to become double than those of the weaker ones, [508] and towards the autumn, when all those of the first group are faded away, and only a weak though large section of the heads is still flowering, the whole aspect of the variety gradually retrogrades. The same law of dependency and periodicity is prevalent everywhere. In my own cultures of the improved field-marigold I have observed it frequently. The number of the ray-florets may be considered as a direct response to nourishment, both when this is determined by external circumstances, and when it depends on the particular strength of the branch, which bears the head in question. It is a case exactly similar to that of the supernumerary carpels of the pistilloid poppy, and the deductions arrived at with that variety may be applied directly to double flowers. This dependency upon nourishment is of high practical importance in combination with the usual effect of the doubling which makes the flowers sterile. It is a general rule that the most perfect flowers do not produce seed. At the height of the flowering period the external circumstances are the most favorable, and the flowering branches still constitute the stronger axes of the plants. Hence we may infer that sterility will prevail precisely in this period. Many varieties are known to yield only seeds from the very last flowers, as for instance some [509] double begonias. Others bear only seed on their weaker lateral branches, as the double camomile, or become fertile only towards the fall, as is often the case with the above quoted Erfurt variety of the blue-bottle. As far as I have been able to ascertain, such seeds are quite adequate for the reproduction and perpetuation of the double varieties, but the question whether there are differences between the seeds of the more or less double flowers of the same plants still remains open. It is very probable, from a theoretical point of view, that such differences exist, but perhaps they are so slight, as to have practically no bearing on the question. On the ground of their wide range of variability, the double varieties must be regarded as pertaining to the group of ever-sporting forms. On one side they fluctuate in the direction towards such petalomanous flowers as are borne by the stocks and others, which we have previously discussed. Here no trace of the fertile organs is left. But this extreme is never reached by petaloid double flowers. A gap remains which, often overlooked, always exists, and which sharply separates the two types. On the other hand the alteration of the stamens gradually relapses to perfectly single flowers. Here the analogy with the pistillody of the poppies and with the "five-leaved" clover is obvious. [510] This conception of the inner nature of double flowers explains the fact that the varietal mark is seldom seen to be complete throughout larger groups of individuals, providing these have not been already selected by this character. _Tagetes africana_ is liable to produce some poorly filled specimens, and some double varieties of carnations are offered for sale with the note that the seed yields only 80% of doubles. With _Chrysanthemum coronarium_ and blue-bottles this figure is often announced to be only about 50%. No doubt it is partly due to impurities, caused by vicinism, but it is obviously improbable that the effect of these impurities should be so large. Some cases of partial reversion may be interpreted in the same way. Among the garden anemones, _Anemone coronaria_, there is a variety called the "Bride," on account of its pure white dowers. It is for sale with single and with double flowers, and these two forms are known to sport into one another, although they are multiplied in the vegetative way. Such cases are known to be of quite ordinary occurrence. Of course such sports must be considered as partial, and the same stem may bear both types of flowers. It even happens that some particular flower is partly double and partly single. Mr. Krelage, of Haarlem, had the kindness to [511] send me such a curious flower. One half of it was completely double, while the other half was entirely single, bearing normal and fertile stamens in the ordinary number. The same halfway doubling is recorded to occur among composites sometimes, and from the same source I possess in my collection a head of _Pyrethrum roseum_, bearing on half of its disk elongated corolla tubes, and on the other half the small disk-florets of the typical species. It is a current belief, that varieties are improved by continued culture. I have never been able to ascertain the grounds on which this conviction rests. It may be referred either to the purity of the race or to the complete development of the varietal character. In the first case it is a question of hybrid mixtures from which many young varieties must be freed before being placed on the market. But as we have already seen in a former lecture, this requires only three or four years, and afterwards the degree of purity is kept up to the point which proves to be the most suitable for practical purposes. The complete development of the varietal character is a question restricted to ever-sporting varieties, since in white flowers and other constant varieties this degree is variable in a very small and unimportant measure. [512] Hence the double flowers seem to afford a very good example for this discussion. It can be decided by two facts. First by a consideration of the oldest double varieties, and secondly by that of the very youngest. Are the older ones now in a better condition than at the outset? Have they really been gradually improved during the centuries of their existence? Obviously this can only be answered by a comparison of the figures given by older writers, with the varieties as they are now in culture. Munting's drawings and descriptions are now nearly two centuries and a half old, but I do not find any real difference between his double varieties and their present representatives. So it is in other cases in which improvements by crossing or the introduction of new forms does not vitiate the evidence. Double varieties, as a rule, are exactly the same now, as they were at the time of their first introduction. If this were otherwise one would expect that young double varieties should in the main display only slight grades of the anomaly, and that they would require centuries to reach their full development. Nothing of the kind is on record. On the contrary the newest double sorts are said to be not only equal to their predecessors, but to excel them. As a rule such claims may be exaggerated, but not to any great extent. [513] This is proven in the simplest way by the result of our own experiment. In the double field-marigold we have the very first generation of a variety of pure and not hybrid origin. It shows the new attribute in its full development. It has flower-heads nearly as completely filled as the best double varieties of allied cultivated composites. In the second generation it reached heads with 200 rays each, and much larger numbers will seldom be seen in older species on heads of equal size. I have compared my novelty with the choicest double camomiles and others, but failed to discover any real difference. Improvement of the variety developed in the experiments carried on by myself seems to be excluded by the fact that it comes into conflict with the same difficulty that confronts the older cultivated species, viz.: the increasing sterility of the race. It is perfectly evident that this double marigold is now quite constant. Continuously varying about a fixed average it may live through centuries, but the mean and the limits will always remain the same, as in the case of the ever-sporting varieties. Throughout this lecture I have spoken of double flowers and double flower-heads of composites as of one single group. They are as nearly related from the hereditary point of [514] view, as they are divergent in other respects. It would be superfluous to dwell any longer upon the difference between heads and flowers. But it is as well to point out, that the term double flowers indicates a motley assemblage of different phenomena. The hen-and-chicken daisy, and the corresponding variety of the garden cineraria (_Cineraria cruenta_), are extremes on one side. The hen-and-chicken type occurs even in other families and is known to produce most curious anomalies, as with _Scabiosa_, the supernumerary heads of which may be produced on long stalks and become branched themselves in the same manner. Petalody of the stamens is well known to be the ordinary type of doubling. But it is often accompanied by a multiplication of the organs, both of the altered stamens and of the petals themselves. This proliferation may consist in median or in lateral cleavages, and in both cases the process may be repeated one or more times. It would be quite superfluous to give more details, which may be gathered from any morphologic treatise on double flowers. But from the physiologic point of view all these cases are to be considered as one large group, complying with previously given definitions of the ever-sporting varieties. They are very variable and wholly permanent. Obviously this [515] permanency agrees perfectly with the conception of their sudden origin. [516] LECTURE XVIII NEW SPECIES OF _OENOTHERA_ In our experiments on the origin of peloric varieties and double flowers we were guided in the choice of our material by a survey of the evidence already at hand. We chose the types known to be most commonly produced anew, either in the wild state or under the conditions of cultivation. In both instances our novelty was a variety in the ordinary sense of the word. Our pedigree-culture was mainly an experimental demonstration of the validity of conclusions, which had previously been deduced from such observations as can be made after the accidental birth of new forms. From these facts, and even from these pedigree-experiments, it is scarcely allowable to draw conclusions as to the origin of real species. If we want to know how species originate, it is obviously necessary to have recourse to direct observation. The question is of the highest importance, both for the theory of descent, and for our conception of the real nature of [517] systematic affinities at large. Many authors have tried to solve it on the ground of comparative studies and of speculations upon the biologic relations of plants and animals. But in vain. Contradiction and doubt still reign supreme. All our hopes now rest on the result of experiments. Unfortunately such experiments seemed simply impossible a few years ago. What is to guide us in the choice of the material? The answer may only be expected from a consideration of elementary species. For it is obvious that they only can be observed to originate, and that the systematic species, because they are only artificial groups of lower unities, can never become the subject of successful experimental inquiry. In previous lectures we tried to clear up the differences existing between nearly related elementary species. We have seen that they affect all of the attributes of the plants, each of them changing in some measure all of the organs. Nevertheless they were due to distinct unities and of the lowest possible degree. Such unit-steps may therefore be expected to become visible some time or other by artificial means. On the other hand, mutations as a rule make their appearance in groups, and there are many systematic species which on close inspection [518] have been shown to be in reality composite assemblages. Roses and brambles, hawkweeds and willows are the best known examples. Violets and _Draba verna_, dandelions and helianthemums and many other instances were dealt with in previous lectures. Even wheat and barley and corn afford instances of large groups of elementary species. Formerly mixed in the fields, they became separated during the last century, and now constitute constant races, which, for brevity's sake, are dealt with under the name of varieties. In such groups of nearly allied forms the single members must evidently be of common origin. It is not necessary for them to have originated all in the same place or at the same time. In some cases, as with _Draba verna_, the present geographic distribution points to a common birthplace, from whence the various forms may about the same period have radiated in all directions. The violets on the other hand seem to include widely diffused original forms, from which branches have started at different times and in different localities. The origin of such groups of allied forms must therefore be the object of our research. Perhaps we might find a whole group, perhaps only part of it. In my opinion we have the right to assume that if _Draba_ and violets and [519] others have formerly mutated in this way, other species must at present be in the same changeable condition. And if mutations in groups, or such periodic mutations should be the rule, it is to be premised that these periods recur from time to time, and that many species must even now be in mutating condition, while others are not. It is readily granted that the constant condition of species is the normal one, and that mutating periods must be the exception. This fact does not tend to increase our prospect of discovering a species in a state of mutability. Many species will have to be tested before finding an instance. On the other hand, a direct trial seems to be the only way to reach the goal. No such special guides as those that led us to the choice of pelories and double flowers are available. The only indication of value is the presumption that a condition of mutability might be combined with a general state of variability at large, and that groups of plants of very uniform features might be supposed to be constant in this respect too. On the contrary, anomalies and deviations if existent in the members of one strain, or found together in one native locality of a species, might be considered as an indication in the desired direction. Few plants vary in the wild state in such a [520] measure as to give distinct indications. All have to be given a trial in the garden under conditions as similar as possible to their natural environments. Cultivated plants are of course to be excluded. Practically they have already undergone the experience in question and can not be expected to change their habits soon enough. Moreover they are often of hybrid origin. The best way is to experiment with the native plants of one's own country. I have made such experiments with some hundred species that grow wild in Holland. Some were very variable, as for instance, the jointed charlock (_Raphanus Raphanistrum_) and the narrow-leaved plantain (_Plantago lanceolata_). Others seemed more uniform, but many species, collected without showing any malformation, subsequently produced them in my garden, either on the introduced plants themselves or among their offspring. From this initial material I have procured a long series of hereditary races, each with some peculiar anomaly for its special character. But this result was only a secondary gain, a meager consolation for the negative fact that no real mutability could be discovered. My plants were mostly annuals or biennials, or such perennials as under adequate treatment might produce flowers and seeds during their [521] first summer. It would be of no special use to enumerate them. The negative result does not apply to the species as such, but only to the individual strain, which I collected and cultivated. Many species, which are quite constant with us, may be expected to be mutable in other parts of their range. Only one of all my tests met my expectations. This species proved to be in a state of mutation, producing new elementary forms continually, and it soon became the chief member of my experimental garden. It was one of the evening primroses. Several evening-primroses have at different times been introduced into European gardens from America. From thence they have spread into the vicinity, becoming common and exhibiting the behavior of indigenous types. _Oenothera biennis_ was introduced about 1614 from Virginia, or nearly three centuries ago. _O. muricata_, with small corollas and narrow leaves, was introduced in the year 1789 by John Hunneman, and _O. suaveolens_, or sweet-scented primrose, a form very similar to the _biennis_, about the same time, in 1778, by John Fothergill. This form is met with in different parts of France, while the _biennis_ and _muricata_ are very common in the sandy regions of Holland, where I have observed them for [522] more than 40 years. They are very constant and have proven so in my experiments. Besides these three species, the large-flowered evening-primrose, or _Oenothera lamarckiana_, is found in some localities in Holland and elsewhere. We know little concerning its origin. It is supposed to have come from America in the same way as its congeners, but as yet I have not been able to ascertain on what grounds this supposition rests. As far as I know, it has not been seen growing wild in this country, though it may have been overlooked. The fact that the species of this group are subject to many systematic controversies and are combined by different writers into systematic species in different ways, being often considered as varieties of one or two types, easily accounts for it having been overlooked. However, it would be of great interest to ascertain whether _O. lamarckiana_ yet grows in America, and whether it is in the same state of mutability here as it is in Holland. The large-flowered evening-primrose was also cultivated about the beginning of the last century in the gardens of the Museum d'Histoire Naturelle, at Paris, where it was noticed by Lamarck, who at once distinguished it as an undescribed species. He wrote a complete description [523] of it and his type specimens are still preserved in the herbarium of the Museum, where I have compared them with the plants of my own culture. Shortly afterwards it was renamed by Seringe, in honor of its eminent discoverer, whose name it now bears. So Lamarck unconsciously discovered and described himself the plant, which after a century, was to become the means of an empirical demonstration of his far-reaching views on the common origin of all living beings. _Oenothera lamarckiana_ is considered in Europe as a garden-plant, much prized for parks and ornamental planting. It is cultivated by seed-merchants and offered for sale. It has escaped from gardens, and having abundant means for rapid multiplication, has become wild in many places. As far as I know its known localities are small, and it is to be presumed that in each of them the plant has escaped separately from culture. It was in this state that I first met with this beautiful species. Lamarck's evening-primrose is a stately plant, with a stout stem, attaining often a height of 1.6 meters and more. When not crowded the main stem is surrounded by a large circle of smaller branches, growing upwards from its base so as often to form a dense bush. These branches in their turn have numerous lateral [524] branches. Most of them are crowned with flowers in summer, which regularly succeed each other, leaving behind them long spikes of young fruits. The flowers are large and of a bright yellow color, attracting immediate attention, even from a distance. They open towards evening, as the name indicates, and are pollinated by humble-bees and moths. On bright days their duration is confined to one evening, but during cloudy weather they may still be found open on the following morning. Contrary to their congeners they are dependent on visiting insects for pollination. _O. biennis_ and _O. muricata_ have their stigmas in immediate contact with the anthers within the flower-buds, and as the anthers open in the morning preceding the evening of the display of the petals, fecundation is usually accomplished before the insects are let in. But in _O. lamarckiana_ no such self-fertilization takes place. The stigmas are above the anthers in the bud, and as the style increases in length at the time of the opening of the corolla, they are elevated above the anthers and do not receive the pollen. Ordinarily the flowers remained sterile if not visited by insects or pollinated by myself, although rare instances of self-fertilization were seen. In falling off, the flowers leave behind them a stout ovary with four cells and a large number [525] of young seeds. The capsule when ripe, opens at its summit with four valves, and contains often from two to three hundred seeds. A hundred capsules on the main stem is an average estimate, and the lateral branches may ripen even still more fruits, by which a very rapid dissemination is ensured. This striking species was found in a locality near Hilvers, in the vicinity of Amsterdam, where it grew in some thousands of individuals. Ordinarily biennial, it produces rosettes in the first, and stems in the second year. Both the stems and the rosettes were at once seen to be highly variable, and soon distinct varieties could be distinguished among them. The first discovery of this locality was made in 1886. Afterwards I visited it many times, often weekly or even daily during the first few years, and always at least once a year up to the present time. This stately plant showed the long-sought peculiarity of producing a number of new species every year. Some of them were observed directly on the field, either as stems or as rosettes. The latter could be transplanted into my garden for further observation, and the stems yielded seeds to be sown under like control. Others were too weak to live a sufficiently long time in the field. They were discovered by sowing seed from indifferent plants [526] of the wild locality in the garden. A third and last method of getting still more new species from the original strain, was the repetition of the sowing process, by saving and sowing the seed which ripened on the introduced plants. These various methods have led to the discovery of over a dozen new types, never previously observed or described. Leaving the physiologic side of the relations of these new forms for the next lecture, it would be profitable to give a short description of the several novelties. To this end they may be combined under five different heads, according to their systematic value. The first head includes those which are evidently to be considered as varieties, in the narrower sense of the word, as previously given. The second and third heads indicate the real progressive elementary species, first those which are as strong as the parent-species, and secondly a group of weaker types, apparently not destined to be successful. Under the fourth head I shall include some inconstant forms, and under the last head those that are organically incomplete. Of varieties with a negative attribute, or real retrograde varieties, I have found three, all of them in a flowering condition in the field. I have given them the names of _laevifolia_, _brevistylis_ and _nanella_. [527] The _laevifolia_, or smooth-leaved variety, was one of the very first deviating types found in the original field. This was in the summer of 1887, seventeen years ago. It formed a little group of plants growing at some distance from the main body, in the same field. I found some rosettes and some flowering stems and sowed some seed in the fall. The variety has been quite constant in the field, neither increasing in number of individual plants nor changing its place, though now closely surrounded by other _Lamarckiana_s. In my garden it has proved to be constant from seed, never reverting to the original _lamarckiana_, provided intercrossing was excluded. It is chiefly distinguished from Lamarck's evening-primrose by its smooth leaves, as the name indicates. The leaves of the original form show numerous sinuosities in their blades, not at the edge, but anywhere between the veins. The blade shows numbers of convexities on either surface, the whole surface being undulated in this manner; it lacks also the brightness of the ordinary evening-primrose or _Oenothera biennis_. These undulations are lacking or at least very rare on the leaves of the new _laevifolia_. Ordinarily they are wholly wanting, but at times single leaves with slight manifestations of this [528] character may make their appearance. They warn us that the capacity for such sinuosities is not wholly lost, but only lies dormant in the new variety. It is reduced to a latent state, exactly as are the apparently lost characters of so many ordinary horticultural varieties. Lacking the undulations, the _laevifolia_ leaves are smooth and bright. They are a little narrower and more slender than those of the _lamarckiana_. The convexities and concavities of leaves are said to be useful in dry seasons, but during wet summers, such as those of the last few years, they must be considered as very harmful, as they retain some of the water which falls on the plants, prolonging the action of the water on the leaves. This is considered by some writers to be of some utility after slight showers, but was observed to be a source of weakness during wet weather in my garden, preventing the leaves from drying. Whether the _laevifolia_ would do better under such circumstances, remains to be tested. The flowers of the _laevifolia_ are also in a slight degree different from those of _lamarckiana_. The yellow color is paler and the petals are smoother. Later, in the fall, on the weaker side branches these differences increase. The _laevifolia_ petals become smaller and are often not emarginated at the apex, becoming ovate [529] instead of obcordate. This shape is often the most easily recognized and most striking mark of the variety. In respect to the reproductive organs, the fertility and abundance of good seed, the _laevifolia_ is by no means inferior or superior to the original species. _O. brevistylis_, or the short-styled evening primrose, is the most curious of all my new forms. It has very short styles, which bring the stigmas only up to the throat of the calyx tube, instead of upwards of the anthers. The stigmas themselves are of a different shape, more flattened and not cylindrical. The pollen falls from the anthers abundantly on them, and germinates in the ordinary manner. The ovary which in _lamarckiana_ and in all other new forms is wholly underneath the calyx-tube, is here only partially so. This tube is inserted at some distance under its summit. The insertion divides the ovary into two parts: an upper and a lower one. The upper part is much reduced in breadth and somewhat attenuated, simulating a prolongation of the base of the style. The lower part is also reduced, but in another manner. At the time of flowering it is like the ovary of _lamarckiana_, neither smaller nor larger. But it is reached by only a very few pollen-tubes, and is therefore always incompletely fertilized. It does [530] not fall off after the fading away of the flower, as unfertilized ovaries usually do; neither does it grow out, nor assume the upright position of normal capsules. It is checked in its development, and at the time of ripening it is nearly of the same length as in the beginning. Many of them contain no good seeds at all; from others I have succeeded in saving only a hundred seeds from thousands of capsules. These seeds, if purely pollinated, and with the exclusion of the visits of insects, reproduce the variety, entirely and without any reversion to the _lamarckiana_ type. Correlated with the detailed structures is the form of the flower-buds. They lack the high stigma placed above the anthers, which in the _lamarckiana_, by the vigorous growth of the style, extends the calyx and renders the flower bud thinner and more slender. Those of the _brevistylis_ are therefore broader and more swollen. It is quite easy to distinguish the individuals by this striking character alone, although it differs from the parent in other particulars. The leaves of the _O. brevistylis_ are more rounded at the tip, but the difference is only pronounced at times, slightly in the adult rosettes, but more clearly on the growing summits of the stems and branches. By this character, the plants [531] may be discerned among the others, some weeks before the flowers begin to show themselves. But the character by which the plants may be most easily recognized from a distance in the field is the failure of the fruits. They were found there nearly every year in varying, but always small numbers. Leaving the short-styled primrose, we come now to the last of our group of retrograde varieties. This is the _O. nanella_, or the dwarf, and is a most attractive little plant. It is very short of stature, reaching often a height of only 20-30 cm., or less than one-fourth of that of the parent. It commences flowering at a height of 10-15 cm., while the parent-form often measures nearly a meter at this stage of its development. Being so very dwarfed the large flowers are all the more striking. They are hardly inferior to those of the _lamarckiana_, and agree with them in structure. When they fade away the spike is rapidly lengthened, and often becomes much longer than the lower or vegetative part of the stem. The dwarfs are one of the most common mutations in my garden, and were observed in the native locality and also grown from seeds saved there. Once produced they are absolutely constant. I have tried many thousands of seeds from various dwarf mutants, and never observed [532] any trace of reversion to the _lamarckiana_ type. I have also cultivated them in successive generations with the same result. In a former lecture we have seen that contrary to the general run of horticultural belief, varieties are as constant as the best species, if kept free from hybrid admixtures. This is a general rule, and the exceptions, or cases of atavism are extremely rare. In this respect it is of great interest to observe that this constancy is not an acquired quality, but is to be considered as innate, because it is already fully developed at the very moment when the original mutation takes place. From its first leaves to the rosette period, and through this to the lengthening of the stem, the dwarfs are easily distinguished from any other of their congeners. The most remarkable feature is the shape of the leaves. They are broader and shorter, and especially at the base they are broadened in such a way as to become apparently sessile. The stalk is very brittle, and any rough treatment may cause the leaves to break off. The young seedlings are recognizable by the shape of the first two or three leaves, and when more of them are produced, the rosettes become dense and strikingly different from others. Later leaves are more nearly like the parent-type, but the petioles remain short. The bases of the blades are frequently [533] almost cordate, the laminae themselves varying from oblong-ovate to ovate in outline. The stems are often quite unbranched, or branched only at the base of the spike. Strong secondary stems are a striking attribute of the _lamarckiana_ parent, but they are lacking, or almost so in the dwarfs. The stem is straight and short, and this, combined with the large crown of bright flowers, makes the dwarfs eminently suitable for bed or border plants. Unfortunately they are very sensitive, especially to wet weather. _Oenothera gigas_ and _O. rubrinervis_, or the giant, and the red-veined evening-primroses, are the names given to two robust and stout species, which seem to be equal in vigor to the parent-plant, while diverging from it in striking characters. Both are true elementary species, differentiated from _lamarckiana_ in nearly all their organs and qualities, but not showing any preponderating character of a retrograde nature. Their differences may be compared with those of the elementary species of other genera, as for instance, of _Draba_, or of violets, as will be seen by their description. The giant evening-primrose, though not taller in stature than _O. lamarckiana_, deserves its name because it is so much stouter in all respects. [534] The stems are robust, often with twice the diameter of _lamarckiana_ throughout. The internodes are shorter, and the leaves more numerous, covering the stems with a denser foliage. This shortness of the internodes extends itself to the spike, and for this reason the flowers and fruits grow closer together than on the parent-plant. Hence the crown of bright flowers, opening each evening, is more dense and more strikingly brilliant, so much the more so as the individual flowers are markedly larger than those of the parents. In connection with these characters, the flower-buds are seen to be much stouter than those of _lamarckiana_. The fruits attain only half the normal size, but are broader and contain fewer, but larger seeds. The _rubrinervis_ is in many respects a counterpart to the _gigasv, but its stature is more slender. The spikes and flowers are those of the _lamarckianav, but the bracts are narrower. Red veins and red streaks on the fruits afford a striking differentiating mark, though they are not absolutely lacking in the parent-species. A red hue may be seen on the calyx, and even the yellow color of the petals is somewhat deepened in the same way. Young plants are often marked by the pale red tinge of the mid-veins, but in adult rosettes, or from lack of sunshine, this hue is often very faint. [535] The leaves are narrow, and a curious feature of this species is the great brittleness of the leaves and stems, especially in annual individuals, especially in those that make their stem and flowers in the first year. High turgidity and weak development of the mechanical and supporting tissues are the anatomical cause of this deficiency, the bast-fibers showing thinner walls than those of the parent-type under the microscope. Young stems of _rubrinervis_ may be broken off by a sharp stroke, and show a smooth rupture across all the tissues, while those of _lamarckiana_ are very tough and strong. Both the giant and the red-veined species are easily recognized in the rosette-stage. Even the very young seedlings of the latter are clearly differentiated from the _lamarckiana_, but often a dozen leaves are required, before the difference may be seen. Under such circumstances the young plants must reach an age of about two months before it is possible to discern their characters, or at least before these characters have become reliable enough to enable us to judge of each individual without doubt. But the divergencies rapidly become greater. The leaves of _O. gigas_ are broader, of a deeper green, the blade more sharply set off against the stalk, all the rosettes [536] becoming stout and crowded with leaves. Those of _O. rubrinervis_ on the contrary are thin, of a paler green and with a silvery white surface; the blades are elliptic, often being only 2 cm. or less in width. They are acute at the apex and gradually narrowed into the petiole. It is quite evident that such pale narrow leaves must produce smaller quantities of organic food than the darker green and broad organs of the _gigas_. Perhaps this fact is accountable partly, at least, for the more robust growth of the giant in the second year. Perhaps also some relation exists between this difference in chemical activity and the tendency to become annual or biennial. The _gigas_, as a rule, produces far more, and the _rubrinervis_ far less biennial plants than the _lamarckiana_. Annual culture for the one is as unreliable as biennial culture for the other. _Rubrinervis_ may be annual in apparently all specimens, in sunny seasons, but _gigas_ will ordinarily remain in the state of rosettes during the entire first summer. It would be very interesting to obtain a fuller insight into the relation of the length of life to other qualities, but as yet the facts can only be detailed as they stand. Both of these stout species have been found [537] quite constant from the very first moment of their appearance. I have cultivated them from seed in large numbers, and they have never reverted to the _lamarckiana_. From this they have inherited the mutability or the capacity of producing at their turn new mutants. But they seem to have done so incompletely, changing in the direction of more absolute constancy. This was especially observed in the case of _rubrinervis_, which is not of such rare occurrence as _O. gigas_, and which it has been possible to study in large numbers of individuals. So for instance, the "red-veins" have never produced any dwarfs, notwithstanding they are produced very often by the parent-type. And in crossing experiments also the red-veins gave proof of the absence of a mutative capacity for their production. Leaving the robust novelties, we may now take up a couple of forms, which are equally constants and differentiated from the parent species in exactly the same manner, though by other characters, but which are so obviously weak as to have no manifest chance of self maintenance in the wild state. These are the whitish and the oblong-leaved evening-primroses or the _Oenothera albida_ and _oblonga_. _Oenothera albida_ is a very weak species, with whitish, narrow leaves, which are evidently incapable [538] of producing sufficient quantities of organic food. The young seedling-plants are soon seen to lag behind, and if no care is taken of them they are overgrown by their neighbors. It is necessary to take them out, to transplant them into pots with richly manured soil, and to give them all the care that should be given to weak and sickly plants. If this is done fully grown rosettes may be produced, which are strong enough to keep through the winter. In this case the individual leaves become stronger and broader, with oblong blades and long stalks, but retain their characteristic whitish color. In the second year the stems become relatively stout. Not that they become equal to those of _lamarckiana_, but they become taller than might have been expected from the weakness of the plants in the previous stages. The flowers and racemes are nearly as large as those of the parent-form, the fruits only a little thinner and containing a smaller quantity of seed. From these seeds I have grown a second and a third generation, and observed that the plants remain true to their type. _O. oblonga_ may be grown either as an annual, or as a biennial. In the first case it is very slender and weak, bearing only small fruits and few seeds. In the alternative case however, it [539] becomes densely branched, bearing flowers on quite a number of racemes and yielding a full harvest of seeds. But it always remains a small plant, reaching about half the height of that of _lamarckiana_. When very young it has broader leaves, but in the adult rosettes the leaves become very narrow, but fleshy and of a bright green color. They are so crowded as to leave no space between them unoccupied. The flowering spikes of the second year bear long leaf-like bracts under the first few flowers, but those arising later are much shorter. Numerous little capsules cover the axis of the spike after the fading away of the petals, constituting a very striking differentiating mark. This species also was found to be quite constant, if grown from pure seed. We have now given the descriptions of seven new forms, which diverge in different ways from the parent-type. All were absolutely constant from seed. Hundreds or thousands of seedlings may have arisen, but they always come true and never revert to the original _O. lamarckiana_ type. From this they have inherited the condition of mutability, either completely or partly, and according to this they may be able to produce new forms themselves. But this occurs only rarely, and combinations of more than one [540] type in one single plant seem to be limited to the admixture of the dwarf stature with the characters of the other new species. These seven novelties do not comprise the whole range of the new productions of my _O. lamarckiana_. But they are the most interesting ones. Others, as the _O. semilata_ and the _O. leptocarpa_ are quite as constant and quite as distinct, but have no special claims for a closer description. Others again were sterile, or too weak to reach the adult stage and to yield seeds, and no reliable description or appreciation can be given on the ground of the appearance of a single individual. Contrasted with these groups of constant forms are three inconstant types which we now take up. They belong to two different groups, according to the cause of their inconstancy. In one species which I call _O. lata_, the question of stability or instability must remain wholly unsolved, as only pistillate flowers are produced, and no seed can be fertilized save by the use of the pollen of another form, and therefore by hybridization. The other head comprises two fertile forms, _O. scintillans_ and _O. elliptica_, which may easily be fertilized with their own pollen, but which gave a progeny only partly similar to the parents. The _Oenothera lata_ is a very distinct form [541] which was found more than once in the field, and recently (1902) in a luxuriant flowering specimen. It has likewise been raised from seeds collected in different years at the original station. It is also wholly pistillate. Apparently the anthers are robust, but they are dry, wrinkled and nearly devoid of contents. The inner wall of cells around the groups of pollen grow out instead of being resorbed, partly filling the cavity which is left free by the miscarriage of the pollen-grains. This miscarriage does not affect all the grains in the same degree, and under the microscope a few of them with an apparently normal structure may be seen. But the contents are not normally developed, and I have tried in vain to obtain fertilization with a large number of flowers. Only by cross-fertilization does _O. lata_ produce seeds, and then as freely as the other species when self-fertilized. Of course its chance of ever founding a wild type is precluded by this defect. _O. lata_ is a low plant, with a limp stem, bent tips and branches, all very brittle, but with dense foliage and luxuriant growth. It has bright yellow flowers and thick flower-buds. But for an unknown reason the petals are apt to unfold only partially and to remain wrinkled throughout the flowering time. The stigmas are slightly divergent from the normal type, [542] also being partly united with one another, and laterally with the summit of the style, but without detriment to their function. Young seedlings of _lata_ may be recognized by the very first leaves. They have a nearly orbicular shape and are very sharply set off against their stalk. The surface is very uneven, with convexities and concavities on both sides. This difference is lessened in the later leaves, but remains visible throughout the whole life of the plant, even during the flowering season. Broad, sinuate leaves with rounded tips are a sure mark of _O. lata_. On the summits of the stems and branches they are crowded so as to form rosettes. Concerning inheritance of these characteristics nothing can be directly asserted because of the lack of pollen. The new type can only be perpetuated by crosses, either with the parent form or some other mutant. I have fertilized it, as a rule, with _lamarckiana_ pollen, but have often also used that from _nanella_ and others. In doing so, the _lata_ repeats its character in part of its offspring. This part seems to be independent of the nature of the pollen used, but is very variable according to external circumstances. On the average one-fourth of the offspring become _lata_, the others assuming the type of the pollen-parent, if this was a _lamarckiana_ or [543] partly this type and partly that of any other of the new species derived from _lamarckiana_, that might have been used as the pollen-parent. This average seems to be a general rule, recurring in all experiments, and remaining unchanged through a long series of successive generations. The fluctuations around this mean go up to nearly 50% and down nearly to 1%, but, as in other cases, such extreme deviations from the average are met with only exceptionally. The second category includes the inconstant but perfectly fertile species. I have already given the names of the only two forms, which deserve to be mentioned here. One of them is called _scintillans_ or the shiny evening-primrose, because its leaves are of a deep green color with smooth surfaces, glistening in the sunshine. On the young rosettes these leaves are somewhat broader, and afterwards somewhat narrower than those of _O. lamarckiana_ at the corresponding ages. The plants themselves always remain small, never reaching the stature of the ancestral type. They are likewise much less branched. They can easily be cultivated in annual generations, but then do not become as fully developed and as fertile, as when flowering in the second year. The flowers have the same structure as those of the _lamarckiana_, but are of a smaller size. [544] Fertilizing the flowers artificially with their own pollen, excluding the visiting insects by means of paper bags, and saving and sowing the seed of each individual separately, furnishes all the requisites for the estimation of the degree of stability of this species. In the first few weeks the seed-pans do not show any unequality, and often the young plants must be replanted at wider intervals, before anything can be made out with certainty. But as soon as the rosettes begin to fill it becomes manifest that some of them are more backward than others in size. Soon the smaller ones show their deeper green and broader leaves, and thereby display the attributes of the _scintillans_. The other grow faster and stronger and exhibit all the characteristics of ordinary _lamarckiana_s. The numerical proportion of these two groups has been found different on different occasions. Some plants give about one-third _scintillans_ and two-thirds _lamarckiana_, while the progeny of individuals of another strain show exactly the reverse proportion. Two points deserve to be noticed. First the progeny of the _scintillans_ appears to be mutable in a large degree, exceeding even the _lamarckiana_. The same forms that are produced most often by the parent-family are also most ordinarily [545] met with among the offspring of the shiny evening-primrose. They are _oblonga_, _lata_ and _nanella_. _Oblonga_ was observed at times to constitute as much as 1% or more of the sowings of _scintillans_, while _lata_ and _nanella_ were commonly seen only in a few scattering individuals, although seldom lacking in experiments of a sufficient size. Secondly the instability seems to be a constant quality, although the words themselves are at first sight, contradictory. I mean to convey the conception that the degree of instability remains unchanged during successive generations. This is a very curious fact, and strongly reminds us of the hereditary conditions of striped-flower varieties. But, on the contrary, the atavists, which are here the individuals with the stature and the characteristics of the _lamarckiana_, have become _lamarckiana_s in their hereditary qualities, too. If their seed is saved and sown, their progeny does not contain any _scintillans_, or at least no more than might arise by ordinary mutations. One other inconstant new species is to be noted, but as it was very rare both in the field and in my cultures, and as it was difficult of cultivation, little can as yet be said about it. It is the _Oenothera elliptica_, with narrow elliptical leaves and also with elliptical petals. It repeats [546] its type only in a very small proportion of its seed. All in all we thus have a group of a dozen new types, springing from an original form in one restricted locality, and seen to grow there, or arising in the garden from seeds collected from the original locality. Without any doubt the germs of the new types are fully developed within the seed, ready to be evolved at the time of germination. More favorable conditions in the field would no doubt allow all of the described new species to unfold their attributes there, and to come into competition with each other and with the common parents. But obviously this is only of secondary importance, and has no influence on the fact that a number of new types, analogous to the older swarms of _Draba_, _Viola_ and of many other polymorphous species, have been seen to arise directly in the wild state. [547] LECTURE XIX EXPERIMENTAL PEDIGREE-CULTURES The observation of the production of mutants in the field at Hilversum, and the subsequent cultivation of the new types in the garden at Amsterdam, gives ample proof of the mutability of plants. Furthermore it furnishes an analogy with the hypothetical origin of the swarms of species of _Draba_ and _Viola_. Last but not least important it affords material for a complete systematic and morphologic study of the newly arisen group of forms. The physiologic laws, however, which govern this process are only very imperfectly revealed by such a study. The instances are too few. Moreover the seeds from which the mutants spring, escape observation. It is simply impossible to tell from which individual plants they have been derived. The laevifolia and the brevistylis have been found almost every year, the first always recurring on the same spot, the second on various parts of the original field. It is therefore allowable to assume a common [548] origin for all the observed individuals of either strain. But whether, besides this, similar strains are produced anew by the old _lamarckiana_ group, it is impossible to decide on the sole ground of these field-observations. The same holds good with the other novelties. Even if one of them should germinate repeatedly, without ever opening its flowers, the possibility could not be excluded that the seeds might have come originally from the same capsule but lain dormant in the earth during periods of unequal length. Other objections might be cited that can only be met by direct and fully controlled experiments. Next to the native locality comes the experimental garden. Here the rule prevails that every plant must be fertilized with pollen of its own, or with pollen of other individuals of known and recorded origin. The visits of insects must be guarded against, and no seeds should be saved from flowers which have been allowed to open without this precaution. Then the seeds of each individual must be saved and sown separately, so as to admit of an appreciation, and if necessary, a numerical determination of the nature of its progeny. And last but not least the experiments should be conducted in a similar manner during a series of successive years. [549] I have made four such experiments, each comprising the handling of many thousands of individual plants, and lasting through five to nine generations. At the beginning the plants were biennial, as in the native locality, but later I learned to cultivate them in annual generations. They have been started from different plants and seeds, introduced from the original field into my garden at Amsterdam. It seems sufficient to describe here one of these pedigree-cultures, as the results of all four were similar. In the fall of 1886 I took nine large rosettes from the field, planted them together on an isolated spot in the garden, and harvested their seeds the next year. These nine original plants are therefore to be considered as constituting the first generation of my race. The second generation was sown in 1888 and flowered in 1889. It at once yielded the expected result. 15,000 seedlings were tested and examined, and among them 10 showed diverging characters. They were properly protected, and proved to belong to two new types. 5 of them were _lata_ and 5 _nanella_. They flowered next year and displayed all the characters as described in our preceding lecture. Intermediates between them and the general type were not found, and no indication of their appearance was noted in their parents. [550] They came into existence at once, fully equipped, without preparation or intermediate steps. No series of generations, no selection, no struggle for existence was needed. It was a sudden leap into another type, a sport in the best acceptation of the word. It fulfilled my hopes, and at once gave proof of the possibility of the direct observation of the origin of species, and of the experimental control thereof. The third generation was in the main a repetition of the second. I tried some 10,000 seedlings and found three _lata_ and three _nanella_, or nearly the same proportion as in the first instance. But besides these a _rubrinervis_ made its appearance and flowered the following year. This fact at once revealed the possibility that the instability of _lamarckiana_ might not be restricted to the three new types now under observation. Hence the question arose how it would be possible to obtain other types or to find them if they were present. It was necessary to have better methods of cultivation and examination of the young plants. Accordingly I devoted the three succeeding years to working on this problem. I found that it was not at all necessary to sow any larger quantities of seed, but that the young plants must have room enough to develop into full and free rosettes. Moreover I observed [551] that the attributes of _lata_ and _nanella_, which I now studied in the offspring of my first mutants, were clearly discernible in extreme youth, while those of _rubrinervis_ remained concealed some weeks longer. Hence I concluded that the young plants should be examined from time to time until they proved clearly to be only normal _lamarckiana_. Individuals exhibiting any deviation from the type, or even giving only a slight indication of it, were forthwith taken out of the beds and planted separately, under circumstances as favorable as possible. They were established in pots with well-manured soil and kept under glass, but fully exposed to sunshine. As a rule they grew very fast, and could be planted out early in June. Some of them, of course, proved to have been erroneously taken for mutants, but many exhibited new characters. All in all I had 334 young plants which did not agree with the parental type. As I examined some 14,000 seedlings altogether, the result was estimated at about 2.5%. This proportion is much larger than in the yields of the two first generations and illustrates the value of improved methods. No doubt many good mutations had been overlooked in the earlier observations. As was to be expected, _lata_ and _nanella_ [552] were repeated in this third generation (1895). I was sure to get nearly all of them, without any important exceptions, as I now knew how to detect them at almost any age. In fact, I found many of them; as many as 60 _nanella_ and 73 _lata_, or nearly 5% of each. _Rubrinervis_ also recurred, and was seen in 8 specimens. It was much more rare than the two first-named types. But the most curious fact in that year was the appearance of _oblonga_. No doubt I had often seen it in former years, but had not attached any value to the very slight differences from the type, as they then seemed to me. I knew now that any divergence was to be esteemed as important, and should be isolated for further observation. This showed that among the selected specimens not less than 176, or more than 1% belonged to the _oblonga_ type. This type was at that time quite new to me, and it had to be kept through the winter, to obtain stems and flowers. It proved to be as uniform as its three predecessors, and especially as sharply contrasted with _lamarckiana_. The opportunity for the discovery of any intermediates was as favorable as could be, because the distinguishing marks were hardly beyond doubt at the time of the selection and removal of the young plants. But no connecting links were found. [553] The same holds good for _albida_, which appeared in 15 specimens, or in 0.1%, of the whole culture. By careful cultivation these plants proved not to be sickly, but to belong to a new, though weak type. It was evident that I had already seen them in former years, but having failed to recognize them had allowed them to be destroyed at an early age, not knowing how to protect them against adverse circumstances. Even this time I did not succeed in getting them strong enough to keep through the winter. Besides these, two new types were observed, completing the range of all that have since been recorded to regularly occur in this family. They were _scintillans_ and _gigas_. The first was obtained in the way just described. The other hardly escaped being destroyed, not having showed itself early enough, and being left in the bed after the end of the selection. But as it was necessary to keep some rosettes through the winter in order to have biennial flowering plants to furnish seeds, I selected in August about 30 of the most vigorous plants, planted them on another bed and gave them sufficient room for their stems and branches in the following summer. Most of them sent up robust shoots, but no difference was noted till the first flowers opened. One plant had a much larger crown of bright blossoms than any of the others. [554] As soon as these flowers faded away, and the young fruits grew out, it became clear that a new type was showing itself. On that indication I removed all the already fertilized flowers and young fruits, and protected the buds from the visits of insects. Thus the isolated flowers were fertilized with their own pollen only, and I could rely upon the purity of the seed saved. This lot of seeds was sown in the spring of 1897 and yielded a uniform crop of nearly 300 young _gigas_ plants. Having found how much depends upon the treatment, I could gradually decrease the size of my cultures. Evidently the chance of discovering new types would be lessened thereby, but the question as to the repeated production of the same new forms could more easily and more clearly be answered in this way. In the following year (1896) I sowed half as many seeds as formerly, and the result proved quite the same. With the exception of _gigas_ all the described forms sprang anew from the purely fertilized ancestry of normal _lamarckiana_s. It was now the fifth generation of my pedigree, and thus I was absolutely sure that the descendants of the mutants of this year had been pure and without deviation for at least four successive generations. Owing partly to improved methods of selection, [555] partly no doubt to chance, even more mutants were found this year than in the former. Out of some 8,000 seedlings I counted 377 deviating ones, or nearly 5%, which is a high proportion. Most of them were _oblonga_ and _lata_, the same types that had constituted the majority in the former year. _Albida_, _nanella_ and _rubrinervis_ appeared in large numbers, and even _scintillans_, of which I had but a single plant in the previous generation, was repeated sixfold. New forms did not arise, and the capacity of my strain seemed exhausted. This conclusion was strengthened by the results of the next three generations, which were made on a much smaller scale and yielded the same, or at least the mutants most commonly seen in previous years. Instead of giving the figures for these last two years separately, I will now summarize my whole experiment in the form of a pedigree. In this the normal _lamarckiana_ was the main line, and seeds were only sown from plants after sufficient isolation either of the plants themselves, or in the latter years by means of paper bags enclosing the inflorescences. I have given the number of seedlings of _lamarckiana_ which were examined each year in the table below. Of course by far the largest number of them were [556] thrown away as soon as they showed their differentiating characters in order to make room for the remaining ones. At last only a few plants were left to blossom in order to perpetuate the race. I have indicated for each generation the number of mutants of each of the observed forms, placing them in vertical columns underneath their respective heads. The three first generations were biennial, but the five last annual. PEDIGREE OF A MUTATING FAMILY OF _OENOTHERA LAMARCKIANA_ IN THE EXPERIMENTAL GARDEN AT AMSTERDAM Gener: O.gig. albida obl. rubrin. Lam. nanella lata. scint. VIII. 5 1 0 1700 21 1 VII. 9 0 3000 11 VI. 11 29 3 1800 9 5 1 V. 25 135 20 8000 49 142 6 IV. 1 15 176 8 14000 60 73 1 III. 1 10000 3 3 II. 15000 5 5 I. 9 It is most striking that the various mutations of the evening-primrose display a great degree of regularity. There is no chaos of forms, no indefinite varying in all degrees and in all directions. Quite on the contrary, it is at once evident that very simple rules govern the whole phenomenon. I shall now attempt to deduce these laws from [557] my experiment. Obviously they apply not only to our evening-primroses, but may be expected to be of general validity. This is at once manifest, if we compare the group of new mutants with the swarms of elementary forms which compose some of the youngest systematic species, and which, as we have seen before, are to be considered as the results of previous mutations. The difference lies in the fact that the evening-primroses have been seen to spring from their ancestors and that the _drabas_ have not. Hence the conclusion that in comparing the two we must leave out the pedigree of the evening-primroses and consider only the group of forms as they finally show themselves. If in doing so we find sufficient similarity, we are justified in the conclusion that the _drabas_ and others have probably originated in the same way as the evening-primroses. Minor points of course will differ, but the main lines cannot have complied with wholly different laws. All so-called swarms of elementary species obviously pertain to a single type, and this type includes our evening-primroses as the only controlled case. Formulating the laws of mutability for the evening-primroses we therefore assume that they hold good for numerous other corresponding cases. [558] I. The first law is, that new elementary species appear suddenly, without intermediate steps. This is a striking point, and the one that is in the most immediate contradiction to current scientific belief. The ordinary conception assumes very slow changes, in fact so slow that centuries are supposed to be required to make the differences appreciable. If this were true, all chance of ever seeing a new species arise would be hopelessly small. Fortunately the evening-primroses exhibit contrary tendencies. One of the great points of pedigree-culture is the fact that the ancestors of every mutant have been controlled and recorded. Those of the last year have seven generations of known _lamarckiana_ parents preceding them. If there had been any visible preparation towards the coming mutation, it could not have escaped observation. Moreover, if visible preparation were the rule, it could hardly go on at the same time and in the same individuals in five or six diverging directions, producing from one parent, _gigas_ and _nanella_, _lata_ and _rubrinervis_, _oblonga_ and _albida_ and even _scintillans_. On the other hand the mutants, that constitute the first representatives of their race, exhibit all the attributes of the new type in full display at once. No series of generations, no selection, [559] no struggle for existence are needed to reach this end. In previous lectures I have mentioned that I have saved the seeds of the mutants whenever possible, and have always obtained repetitions of the prototype only. Reversions are as absolutely lacking as is also a further development of the new type. Even in the case of the inconstant forms, where part of the progeny yearly return to the stature of _lamarckiana_, intermediates are not found. So it is also with _lata_, which is pistillate and can only be propagated by cross-fertilization. But though the current belief would expect intermediates at least in this case, they do not occur. I made a pedigree-culture of lata during eight successive generations, pollinating them in different ways, and always obtained cultures which were partly constituted of _lata_ and partly of _lamarckiana_ specimens. But the _lata_s remained _lata_ in all the various and most noticeable characters, never showing any tendency to gradually revert into the original form. Intermediate forms, if not occurring in the direct line from one species to another, might be expected to appear perhaps on lateral branches. In this case the mutants of one type, appearing in the same year, would not be a pure type, but would exhibit different degrees of deviation from the parent. The best would then have to [560] be chosen in order to get the new type in its pure condition. Nothing of the kind, however, was observed. All the _oblonga_-mutants were pure _oblongas_. The pedigree shows hundreds of them in the succeeding years, but no difference was seen and no material for selection was afforded. All were as nearly equal as the individuals of old elementary species. II. New forms spring laterally from the main stem. The current conception concerning the origin of species assumes that species are slowly converted into others. The conversion is assumed to affect all the individuals in the same direction and in the same degree. The whole group changes its character, acquiring new attributes. By inter-crossing they maintain a common line of progress, one individual never being able to proceed much ahead of the others. The birth of the new species necessarily seemed to involve the death of the old one. This last conclusion, however, is hard to understand. It may be justifiable to assume that all the individuals of one locality are ordinarily intercrossed, and are moreover subjected to the same external conditions. They might be supposed to vary in the same direction if these conditions were changed slowly. But this could of course have no possible influence on the plants of the [561] same species growing in distant localities, and it would be improbable they should be affected in the same way. Hence we should conclude that when a species is converted into a new type in one locality this is only to be considered as one of numerous possible ones, and its alteration would not in the least change the aspect of the remainder of the species. But even with this restriction the general belief is not supported by the evidence of the evening-primroses. There is neither a slow nor a sudden change of all the individuals. On the contrary, the vast majority remain unchanged; thousands are seen exactly repeating the original prototype yearly, both in the native field and in my garden. There is no danger that _lamarckiana_ might die out from the act of mutating, nor that the mutating strain itself would be exposed to ultimate destruction from this cause. In older swarms, such as _Draba_ or _Helianthemum_, no such center, around which the various forms are grouped, is known. Are we to conclude therefore that the main strain has died out? Or is it perhaps concealed among the throng, being distinguished by no peculiar character? If our _gigas_ and _rubrinervis_ were growing in equal numbers with the _lamarckiana_ in the native field, would it be possible to decide [562] which of them was the progenitor of the others? Of course this could be done by long and tedious crossing experiments, showing atavism in the progeny, and thereby indicating the common ancestor. But even this capacity seems to be doubtful and connected only with the state of mutability and to be lost afterwards. Therefore if this period of mutation were ended, probably there would be no way to decide concerning the mutual relationship of the single species. Hence the lack of a recognizable main stem in swarms of elementary species makes it impossible to answer the question concerning their common origin. Another phase of the opposition between the prevailing view and my own results seems far more important. According to the current belief the conversion of a group of plants growing in any locality and flowering simultaneously would be restricted to one type. In my own experiments several new species arose from the parental form at once, giving a wide range of new forms at the same time and under the same conditions. III. New elementary species attain their full constancy at once. Constancy is not the result of selection or of improvement. It is a quality of its own. It can neither be constrained by selection if it is absent [563] from the beginning, nor does it need any natural or artificial aid if it is present. Most of my new species have proved constant from the first. Whenever possible, the original mutants have been isolated during the flowering period and artificially self-fertilized. Such plants have always given a uniform progeny, all children exhibiting the type of the parent. No atavism was observed and therefore no selection was needed or even practicable. Briefly considering the different forms, we may state that the full experimental proof has been given for the origin of _gigas_ and _rubrinervis_, for _albida_ and _oblonga_, and even for _nanella_, which is to be considered as of a varietal nature; with _lata_ the decisive experiment is excluded by its unisexuality. _laevifolia_ and _brevistylis_ were found originally in the field, and never appeared in my cultures. No observations were made as to their origin, and seeds have only been sown from later generations. But these have yielded uniform crops, thereby showing that there is no ground for the assumption that these two older varieties might behave otherwise than the more recent derivatives. _Scintillans_ and _elliptica_ constitute exceptions to the rule given. They repeat their character, from pure seed, only in part of the offspring. I have tried to deliver the _scintillans_ from this [564] incompleteness of heredity, but in vain. The succeeding generations, if produced from true representatives of the new type, and with pure fertilization, have repeated the splitting in the same numerical proportions. The instability seems to be here as permanent a quality as the stability in other instances. Even here no selection has been adequate to change the original form. IV. Some of the new strains are evidently elementary species, while others are to be considered as retrograde varieties. It is often difficult to decide whether a given form belongs to one or another of these two groups. I have tried to show that the best and strictest conception of varieties limits them to those forms that have probably originated by retrograde or degressive steps. Elementary species are assumed to have been produced in a progressive way, adding one new element to the store. Varieties differ from their species clearly in one point, and this is either a distinct loss, or the assumption of a character, which may be met with in other species and genera. _laevifolia_ is distinguished by the loss of the crinkling of the leaves, _brevistylis_ by the partial loss of the epigynous qualities of the flowers, and _nanella_ is a dwarf. These three new forms are therefore [565] considered to constitute only retrograde steps, and no advance. This conclusion has been fully justified by some crossing experiments with _brevistylis_, which wholly complies with Mendel's law, and in one instance with _nanella_, which behaves in the same manner, if crossed with _rubrinervis_. On the other hand, _gigas_ and _rubrinervis_, _oblonga_ and _albida_ obviously bear the characters of progressive elementary species. They are not differentiated from _lamarckiana_ by one or two main features. They diverge from it in nearly all organs, and in all in a definite though small degree. They may be recognized as soon as they have developed their first leaves and remain discernible throughout life. Their characters refer chiefly to the foliage, but no less to the stature, and even the seeds have peculiarities. There can be little doubt but that all the attributes of every new species are derived from one principal change. But why this should affect the foliage in one manner, the flowers in another and the fruits in a third direction, remains obscure. To gain ever so little an insight into the nature of these changes, we may best compare the differences of our evening-primroses with those between the two hundred elementary species of _Draba_ and other similar instances. In doing so we find the same main [566] feature, the minute differences in nearly all points. V. The same new species are produced in a large number of individuals. This is a very curious fact. It embraces two minor points, viz: the multitude of similar mutants in the same year, and the repetition thereof in succeeding generations. Obviously there must be some common cause. This cause must be assumed to lie dormant in the _Lamarckiana_s of my strain, and probably in all of them, as no single parent-plant proved ever to be wholly destitute of mutability. Furthermore the different causes for the sundry mutations must lie latent together in the same parent-plant. They obey the same general laws, become active under similar conditions, some of them being more easily awakened than others. The germs of the _oblonga_, _lata_ and _nanella_ are especially irritable, and are ready to spring into activity at the least summons, while those of _gigas_, _rubrinervis_ and _scintillans_ are far more difficult to arouse. These germs must be assumed to lie dormant during many successive generations. This is especially evident in the case of _lata_ and _nanella__, which appeared in the first year of the pedigree culture and which since have been repeated yearly, and have been seen to arise by mutation [567] also during the last season (1903). Only _gigas_ appeared but once, but then there is every reason to assume that in larger sowings or by a prolongation of the experiments it might have made a second appearance. Is the number of such germs to be supposed to be limited or unlimited? My experiment has produced about a dozen new forms. Without doubt I could easily have succeeded in getting more, if I had had any definite reason to search for them. But such figures are far from favoring the assumption of indefinite mutability. The group of possible new forms is no doubt sharply circumscribed. Partly so by the morphologic peculiarities of _lamarckiana_, which seem to exclude red flowers, composite leaves, etc. No doubt there are more direct reasons for these limits, some changes having taken place initially and others later, while the present mutations are only repetitions of previous ones, and do not contribute new lines of development to those already existing. This leads us to the supposition of some common original cause, which produced a number of changes, but which itself is no longer at work, but has left the affected qualities, and only these, in the state of mutability. In nature, repeated mutations must be of far greater significance than isolated ones. How [568] great is the chance for a single individual to be destroyed in the struggle for life? Hundreds of thousands of seeds are produced by _lamarckiana_ annually in the field, and only some slow increase of the number of specimens can be observed. Many seeds do not find the proper circumstances for germination, or the young seedlings are destroyed by lack of water, of air, or of space. Thousands of them are so crowded when becoming rosettes that only a few succeed in producing stems. Any weakness would have destroyed them. As a matter of fact they are much oftener produced in the seed than seen in the field with the usual unfavorable conditions; the careful sowing of collected seeds has given proof of this fact many times. The experimental proof of this frequency in the origin of new types, seems to overcome many difficulties offered by the current theories on the probable origin of species at large. VI. The relation between mutability and fluctuating variability has always been one of the chief difficulties of the followers of Darwin. The majority assumed that species arise by the slow accumulation of slight fluctuating deviations, and the mutations were only to be considered as extreme fluctuations, obtained, in the main, by a continuous selection of small differences in a constant direction. [569] My cultures show that quite the opposite is to be regarded as fact. All organs and all qualities of _lamarckiana_ fluctuate and vary in a more or less evident manner, and those which I had the opportunity of examining more closely were found to comply with the general laws of fluctuation. But such oscillating changes have nothing in common with the mutations. Their essential character is the heaping up of slight deviations around a mean, and the occurrence of continuous lines of increasing deviations, linking the extremes with this group. Nothing of the kind is observed in the case of mutations. There is no mean for them to be grouped around and the extreme only is to be seen, and it is wholly unconnected with the original type. It might be supposed that on closer inspection each mutation might be brought into connection with some feature of the fluctuating variability. But this is not the case. The dwarfs are not at all the extreme variants of structure, as the fluctuation of the height of the _lamarckiana_ never decreases or even approaches that of the dwarfs. There is always a gap. The smallest specimens of the tall type are commonly the weakest, according to the general rule of the relationship between nourishment and variation, but the tallest dwarfs are of course the most robust specimens of their group. [570] Fluctuating variability, as a rule, is subject to reversion. The seeds of the extremes do not produce an offspring which fluctuates around their parents as a center, but around some point on the line which combines their attributes with the corresponding characteristic of their ancestors, as Vilmorin has put it. No reversion accompanies mutation, and this fact is perhaps the completest contrast in which these two great types of variability are opposed to each other. The offspring of my mutants are, of course, subject to the general laws of fluctuating variability. They vary, however, around their own mean, and this mean is simply the type of the new elementary species. VII. The mutations take place in nearly all directions. Many authors assume that the origin of species is directed by unknown causes. These causes are assumed to work in each single case for the improvement of the animals and plants, changing them in a manner corresponding in a useful way to the changes that take place in their environment. It is not easy to imagine the nature of these influences nor how they would bring about the desired effect. This difficulty was strongly felt by Darwin, and one of the chief purposes of his selection theory may be said to have been the attempt [571] to surmount it. Darwin tried to replace the unknown cause by natural agencies, which lie under our immediate observation. On this point Darwin was superior to his predecessors, and it is chiefly due to the clear conception of this point that his theory has gained its deserved general acceptance. According to Darwin, changes occur in all directions, quite independently of the prevailing circumstances. Some may be favorable, others detrimental, many of them without significance, neither useful nor injurious. Some of them will sooner or later be destroyed, while others will survive, but which of them will survive, is obviously dependent upon whether their particular changes agree with the existing environic conditions or not. This is what Darwin has called the struggle for life. It is a large sieve, and it only acts as such. Some fall through and are annihilated, others remain above and are selected, as the phrase goes. Many are selected, but more are destroyed; daily observation does not leave any doubt upon this point. How the differences originate is quite another question. It has nothing to do with the theory of natural selection nor with the struggle for life. These have an active part only in the accumulation of useful qualities, and only in so [572] far as they protect the bearers of such characters against being crowded out by their more poorly constituted competitors. However, the differentiating characteristics of elementary species are only very small. How widely distant they are from the beautiful adaptative organizations of orchids, of insectivorous plants and of so many others! Here the difference lies in the accumulation of numerous elementary characters, which all contribute to the same end. Chance must have produced them, and this would seem absolutely improbable, even impossible, were it not for Darwin's ingenious theory. Chance there is, but no more than anywhere else. It is not by mere chance that the variations move in the required direction. They do go, according to Darwin's view, in all directions, or at least in many. If these include the useful ones, and if this is repeated a number of times, cumulation is possible; if not, there is simply no progression, and the type remains stable through the ages. Natural selection is continually acting as a sieve, throwing out the useless changes and retaining the real improvements. Hence the accumulation in apparently predisposed directions, and hence the increasing adaptations to the more specialized conditions of life. It must be obvious to any one who can free himself from the current ideas, [573] that this theory of natural selection leaves the question as to how the changes themselves are brought about, quite undecided. There are two possibilities, and both have been propounded by Darwin. One is the accumulation of the slight deviations of fluctuating variability, the other consists of successive sports or leaps taking place in the same direction. In further lectures a critical comparison of the two views will be given. Today I have only to show that the mutations of the evening-primroses, though sudden, comply with the demands made by Darwin as to the form of variability which is to be accepted as the cause of evolution and as the origin of species. Some of my new types are stouter and others weaker than their parents, as shown by _gigas_ and _albida_. Some have broader leaves and some narrower, _lata_ and _oblonga_. Some have larger flowers (_gigas_) or deeper yellow ones (_rubrinervis_), or smaller blossoms (_scintillans_), or of a paler hue (_albida_). In some the capsules are longer (_rubrinervis_), or thicker (_gigas_), or more rounded (_lata_), or small (_oblonga_), and nearly destitute of seeds (_brevistylis_). The unevenness of the surface of the leaves may increase as in _lata_, or decrease as in _laevifolia_. The tendency to become annual prevails in _rubrinervis_, but _gigas_ tends to become [574] biennial. Some are rich in pollen, while _scintillans_ is poor. Some have large seeds, others small. _Lata_ has become pistillate, while _brevistylis_ has nearly lost the faculty to produce seeds. Some undescribed forms were quite sterile, and some I observed which produced no flowers at all. From this statement it may be seen that nearly all qualities vary in opposite directions and that our group of mutants affords wide material for the sifting process of natural selection. On the original field the _laevifolia_ and _brevistylis_ have held their own during sixteen years and probably more, without, however, being able to increase their numbers to any noticeable extent. Others perish as soon as they make their appearance, or a few individuals are allowed to bloom, but probably leave no progeny. But perhaps the circumstances may change, or the whole strain may be dispersed and spread to new localities with different conditions. Some of the latter might be found to be favorable to the robust _gigas_, or to _rubrinervis_, which requires a drier air, with rainfall in the springtime and sunshine during the summer. It would be worth while to see whether the climate of California, where neither _O. lamarckiana_ nor _O. biennis_ are found wild, would not exactly [575] suit the requirements of the new species _rubrinervis_ and _gigas_. NOTE. _Oenothera_s are native to America and all of the species growing in Europe have escaped from gardens directly, or may have arisen by mutation, or by hybridization of introduced species. A fixed hybrid between _O. cruciata_ and _O. biennis_ constituting a species has been in cultivation for many years. The form known as _O. biennis_ in Europe, and used by de Vries in all of the experiments described in these lectures, has not yet been found growing wild in America and is not identical with the species bearing that name among American botanists. Concerning this matter Professor de Vries writes under date of Sept. 12, 1905: "The '_biennis_' which I collected in America has proved to be a motley collection of forms, which at that time I had no means of distinguishing. No one of them, so far as they are now growing in my garden is identical with our _biennis_ of the sand dunes." The same appears to be the case with _O. muricata_. Plants from the Northeastern American seaboard, identifiable with the species do not entirely agree with those raised from seed received from Holland. _O. lamarckiana_ has not been found growing wild in America in recent years although the evidence at hand seems to favor the conclusion that it was seen and collected in the southern states in the last century. (See MacDougal, Vail, Shull, and Small: Mutants and Hybrids of the _Oenotheras_. Publication 24. Carnegie Institution. Washington, D.C., 1905.) EDITOR. [576] LECTURE XX THE ORIGIN OF WILD SPECIES AND VARIETIES New species and varieties occur from time to time in the wild state. Setting aside all theoretical conceptions as to the common origin of species at large, the undoubted fact remains that new forms are sometimes met with. In the case of the peloric toad-flax the mutations are so numerous that they seem to be quite regular. The production of new species of evening-primroses was observed on the field and afterwards duplicated in the garden. There is no reason to think that these cases are isolated instances. Quite on the contrary they seem to be the prototypes of repeated occurrences in nature. If this conception is granted, the question at once arises, how are we to deal with analogous cases, when fortune offers them, and what can we expect to learn from them? A critical study of the existing evidence seems to be of great importance in order to ascertain the best way of dealing with new facts, and of estimating the value of the factors concerned. [577] It is manifest that we must be very careful and conservative in dealing with new facts that are brought to our attention, and every effort should be made to bring additional evidence to light. Many vegetable anomalies are so rare that they are met with only by the purest chance, and are then believed to be wholly new. When a white variety of some common plant is met with for the first time we generally assume that it originated on that very spot and only a short time previously. The discovery of a second locality for the same variety at once raises the question as to a common origin in the two instances. Could not the plants of the second locality have arisen from seeds transported from the first? White varieties of many species of blue-bells and gentians are found not rarely, white-flowering plants of heather, both of _Erica Tetralix_ and _Calluna vulgaris_ occur on European heaths; white flowers of _Brunella vulgaris_, _Ononis repens_, _Thymus vulgaris_ and others may be seen in many localities in the habitats of the colored species. Pelories of labiates seem to occur often in Austria, but are rare in Holland; white bilberries (_Vaccinium Myrtillus_) have many known localities throughout Europe, and nearly all the berry-bearing species in the large heath family are recorded as having white varieties. [578] Are we to assume a single origin for all the representatives of such a variety, as we have done customarily for all the representatives of a wild species? Or can the same mutation have been repeated at different times and in distant localities? If a distinct mutation from a given species is once possible, why should it not occur twice or thrice? A variety which seems to be new to us may only appear so, because the spot where it grows had hitherto escaped observation. _Lychnis preslii_ is a smooth variety of _Lychnis diurna_ and was observed for the first time in the year 1842 by Sekera. It grew abundantly in a grove near Munchengratz in southern Hungary. It was accompanied by the ordinary hairy type of the species. Since then it has been observed to be quite constant in the same locality, and some specimens have been collected for me there lately by Dr. Nemec, of Prague. No other native localities of this variety have been discovered, and there can be no doubt that it must have arisen from the ordinary campion near the spot where it still grows. But this change may have taken place some years before the first discovery, or perhaps one or more centuries ago. This could only be known if it could be proved that the locality had been satisfactorily investigated previously, and that the variety had not [579] been met with. Even in this case only something would be discovered about the time of the change, but nothing about its real nature. So it is in many cases. If a variety is observed in a number of specimens at the time of its first discovery, and at a locality not studied previously, it takes the aspect of an old form of limited distribution, and little can be learned as to the circumstances under which it arose. If on the contrary it occurs in very small numbers or perhaps even in a single individual, and if the spot where it is found is located so that it could hardly have escaped previous observation, then the presumption of a recent origin seems justified. What has to be ascertained on such occasions to give them scientific value? Three points strike me as being of the highest importance. First, the constancy of the new type; secondly, the occurrence or lack of intermediates, and last, but not least, the direct observation of a repeated production. The first two points are easily ascertained. Whether the new type is linked with its more common supposed ancestor by intermediate steps is a query which at once strikes the botanist. It is usually recorded in such cases, and we may state at once that the general result is, that such intermediates do not occur. This is [580] of the highest importance and admits of only two explanations. One is that intermediates may be assumed to have preceded the existent developed form, and to have died out afterwards. But why should they have done so, especially in cases of recent changes? On the other hand the intermediates may be lacking because they have never existed, the change having taken place by a sudden leap, such as the mutations described in our former lectures. It is manifest that the assumption of hypothetical intermediates could only gain some probability if they had been found in some instance. Since they do not occur, the hypothesis seems wholly unsupported. The second point is the constancy of the new type. Seeds should be saved and sown. If the plant fertilizes itself without the aid of insects, as do some evening-primroses, the seed saved from the native locality may prove wholly pure, and if it does give rise to a uniform progeny the constancy of the race may be assumed to be proved, provided that repeated trials do not bring to light any exceptions. If the offspring shows more than one type, cross-fertilization is always to be looked to as the most probable cause, and should be excluded, in order to sow pure seeds. Garden-experiments of this kind, and repeated trials, should always be combined [581] with the discovery of a presumed mutation. In many instances the authors have realized the importance of this point, and new types have been found constant from the very beginning. Many cases are known which show no reversions and even no partial reversions. This fact throws a distinct light on our first point, as it makes the hypothesis of a slow and gradual development still more improbable. My third point is of quite another nature and has not as yet been dealt with. But as it appeals to me as the very soul of the problem, it seems necessary to describe it in some detail. It does not refer to the new type itself, nor to any of its morphologic or hereditary attributes, but directly concerns the presumed ancestors themselves. The peloric toad-flax in my experiment was seen to arise thrice from the same strain. Three different individuals of my original race showed a tendency to produce peloric mutations, and they did so in a number of their seeds, exactly as the mutations of the evening-primroses were repeated nearly every year. Hence the inference, that whenever we find a novelty which is really of very recent date, the parent-strain which has produced it might still be in existence on the same spot. In the case of shrubs or perennials the very parents might yet be found. [582] But it seems probable, and is especially proved in the case of the evening-primroses, that all or the majority of the representatives of the whole strain have the same tendency to mutate. If this were a general rule, it would suffice to take some pure seeds from specimens of the presumed parents and to sow and multiply the individuals to such an extent that the mutation might have a chance to be repeated. Unfortunately, this has not as yet been done, but in my opinion it should be the first effort of any one who has the good luck to discover a new wild mutation. Specimens of the parents should be transplanted into a garden and fertilized under isolated conditions. Seeds saved from the wild plant would have little worth, as they might have been partly fertilized by the new type itself. After this somewhat lengthy discussion of the value of observations surrounding the discovery of new wild mutations, we now come to the description of some of the more interesting cases. As a first example, I will take the globular fruited shepherd's purse, described by Solms Laubach as _Capsella heegeri_. Professor Heeger discovered one plant with deviating fruits, in a group of common shepherd's purses in the market-place near Landau in Germany, in the fall of 1897. They were nearly spherical, [583] instead of flat and purse-shaped. Their valves were thick and fleshy, while those of the ordinary form are membranaceous and dry. The capsules hardly opened and therefore differed in this point from the shepherd's purse, which readily loosens both its valves as soon as it is ripe. Only one plant was observed; whence it came could not be determined, nor whether it had arisen from the neighboring stock of C_apsella_ or not. The discoverer took some seed to his garden and sent some to the botanical garden at Strassburg, of which Solms-Laubach is the director. The majority of the seeds of course were sowed naturally on the original spot. The following year some of the seeds germinated and repeated the novelty. The leaves, stems and flowers were those of the common shepherd's purse, but no decision could be reached concerning the type of this generation before the first flowers had faded and the rounded capsules had developed. Then it was seen that the _heegeri_ came true from seed. It did so both in the gardens and on the market-place, where it was observed to have multiplied and spread in some small measure. The same was noted the following year, but then the place was covered with gravel and all the plants destroyed. It is not recorded to have been seen wild since. [584] Intermediate forms have not been met with. Some slight reversions may occur in the autumn on the smallest and weakest lateral branches. Such reversions, however, seem to be very rare, as I have tried in vain to produce them on large and richly branched individuals, by applying all possible inducements in the form of manure and of cutting, to stimulate the production of successive generations of weaker side branches. This constancy was proved by the experiments of Solms-Laubach, which I have repeated in my own garden during several years with seed received from him. No atavists or deviating specimens have been found among many hundreds of flowering plants. It is important to note that within the family of the crucifers the form of the capsule and the attributes of the valves and seeds are usually considered to furnish the characteristics of genera, and this point has been elucidated at some length by Solms-Laubach. There is, however, no sufficient reason to construe a new genus on the ground of Heeger's globular fruited shepherd's purse; but as a true elementary species, and even as a good systematic species it has proved itself, and as such it is described by Solms-Laubach, who named it in honor of its discoverer. Exactly analogous discoveries have been [586] instead of displaying a bright yellow cup. _O. cruciata_ grows in the Adirondack Mountains, in the states of New York and Vermont, and seems to be abundant there. It has been introduced into botanical gardens and yielded a number of hybrids, especially with _O. biennis and _O. lamarckiana_, and the narrow petals of the parent-species may be met with in combination with the stature and vegetative characteristics of these last named species. _O. cruciata_ has a purple foliage, while _biennis_ and _lamarckiana_ are green, and many of the hybrids may instantly be recognized by their purple color. The curious attribute of the petals is not to be considered simply as a reduction in size. On anatomical inquiry it has been found that these narrow petals bear some characteristics which, on the normal plants, are limited to the calyx. Stomata and hairs, and the whole structure of the surface and inner tissues on some parts of these petals are exactly similar to those of the calyx, while on others they have retained the characteristics of petals. Sometimes there may even be seen by the naked eye green longitudinal stripes of calyx-like structure alternating with bright yellow petaloid parts. For these reasons the cruciata character may be considered as a case of sepalody of the petals, or of the petals being partly converted into sepals. [587] It is worth while to note that as a monstrosity this occurrence is extremely rare throughout the whole vegetable kingdom, and only very few instances have been recorded. Two cases of sudden mutations have come to my knowledge, producing this same anomaly in allied species. One has been already alluded to; it pertains to the common evening-primrose or _Oenothera biennis_, and one is a species belonging to another genus of the same family, the great hairy willow-herb or _Epilobium _hirsutum_. I propose to designate both new forms by the varietal name of _cruciata_, or _cruciatum_. _Oenothera biennis cruciata_ was found in a native locality of the _O. biennis itself. It consisted of only one plant, showing in all its flowers the _cruciata_ marks. In all other respects it resembled wholly the _biennis_, especially in the pure green color of its foliage, which at once excluded all suspicion of hybrid origin with the purple _O. cruciata_. Moreover in our country this last occurs only in the cultivated state in botanical gardens. Intermediates were not seen, and as the plant bore some pods, it was possible to test its constancy. I raised about 500 plants from its seeds, out of which more than 100 flowered in the first year. The others were partly kept through the winter and flowered next year. Seeds saved in [588] both seasons were sown on a large scale. Both the first and the succeeding generations of the offspring of the original plant came true without any exception. Intermediates are often found in hybrid cultures, and in them the character is a very variable one, but as yet they were not met with in progeny of this mutant. All these plants were exactly like _O. biennis_, with the single exception of their petals. _Epilobium hirsutum cruciatum_ was discovered by John Rasor near Woolpit, Bury St. Edmunds, in England. It flowered in one spot, producing about a dozen stems, among large quantities of the parent-species, which is very common there, as it is elsewhere in Europe. This species is a perennial, multiplying itself by underground runners, and the stems of the new variety were observed to stand so close to each other that they might be considered as the shoots of one individual. In this case this specimen might probably be the original mutant, as the variety had not been seen on that spot in previous years, even as it has not been found elsewhere in the vicinity. Intermediates were not observed, though the difference is a very striking one. In the cruciate flowers the broad and bright purple petals seem at first sight to be wholly wanting. They are too weak to expand and to reflex the calyx [589] as in the normal flowers of the species. The sepals adhere to one another, and are only opened at their summit by the protruding pistils. Even the stamens hardly come to light. At the period of full bloom the flowers convey only the idea of closed buds crowned by the conspicuous white cross of the stigma. Any intermediate form would have at once betrayed itself by larger colored petals, coming out of the calyx-sheath. The cruciate petals are small and linear and greenish, recalling thereby the color of the sepals. Mr. Rasor having sent me some flowers and some ripe capsules of his novelty, I sowed the latter in my experimental garden, where the plant flowered in large numbers and with many thousands of flowers both in 1902 and 1903. All of these plants and all of these flowers repeated the cruciate type exactly, and not the slightest impurity or tendency to partial reversion has been observed. Thus true and constant cruciate varieties have been produced from accidentally observed initial plants, and because of their very curious characters they will no doubt be kept in botanical gardens, even if they should eventually become lost in their native localities. At this point I might note another observation made on the wild species of _Oenothera cruciata_ [590] from the Adirondacks. Through the kindness of Dr. MacDougal, of the New York Botanical Garden, I received seeds from Sandy Hill near Lake George. When the plants, grown from these seeds, flowered, they were not a uniform lot, but exhibited two distinct types. Some had linear petals and thin flower-buds, and in others the petals were a little broader and the buds more swollen. The difference was small, but constant on all the flowers, each single plant clearly belonging to one or the other of the two types. Probably two elementary species were intermixed here, but whether one is the systematic type and the other a mutation, remains to be seen. Nor seem these two types to exhaust the range of variability of _Oenothera cruciata_. Dr. B.L. Robinson of Cambridge, Mass., had the kindness to send me seeds from another locality in the same region. The seeds were collected in New Hampshire and in my garden produced a true and constant _cruciata_, but with quite different secondary characters from both the aforesaid varieties. The stems and flower-spikes and even the whole foliage were much more slender, and the calyx-tubes of the flowers were noticeably more elongated. It seems not improbable that _Oenothera cruciata_ includes a group of lesser unities, and may prove to comprise a [591] swarm of elementary species, while the original strain might even now be still in a condition of mutability. A close scrutiny in the native region is likely to reveal many unexpected features. A very interesting novelty has already been described in a former lecture. It is the _Xanthium wootoni_, discovered in the region about Las Vegas, New Mexico, by T.D.A. Cockerell. It is similar in all respects to _X. commune_, but the burrs are more slender and the prickles much less numerous, and mostly stouter at their base. It grows in the same localities as the _X. commune_, and is not recorded to occur elsewhere. Whether it is an old variety or a recent mutation it is of course impossible to decide. In a culture made in my garden from the seed sent me by Mr. Cockerell, I observed (1903) that both forms had a subvariety with brownish foliage, and, besides this, one of a pure green. Possibly this species, too, is still in a mutable condition. Perhaps the same may be asserted concerning the beautiful shrub, _Hibiscus Moscheutos_, observed in quite a number of divergent types by John W. Harshberger. They grew in a small meadow at Seaside Park, New Jersey, in a locality which had been undisturbed for years. They differed from each other in nearly all the [592] organs, in size, in the diameter of the stems, which were woody in some and more fleshy in others, in the shape of the foliage and in the flowers. More than twenty types could be distinguished and seeds were saved from a number of them, in order to ascertain whether they are constant, or whether perhaps a main stem in a mutating condition might be found among them. If this should prove to be the case, the relations between the observed forms would probably be analogous to those between the _O. lamarckiana_ and its derivatives. Many other varieties have sprung from the type-species under similar conditions from time to time. A fern-leaved mercury, _Mercurialis annua laciniata_, was discovered in the year 1719 by Marchant. The type was quite new at the time and maintained itself during a series of years. The yellow deadly nightshade or _Atropa Belladonna lutea_ was found about 1850 in the Black Forest in Germany in a single spot, and has since been multiplied by seeds. It is now dispersed in botanical gardens, and seems to be quite constant. A dwarf variety of a bean, _Phaseolus lunatus_, was observed to spring from the ordinary type by a sudden leap about 1895 by W.W. Tracy, and many similar cases could be given. The annual habit is not very favorable for [593] the discovery of new forms in the wild state. New varieties may appear, but may be crowded out the first year. The chances are much greater with perennials, and still greater with shrubs or trees. A single aberrant specimen may live for years and even for centuries, and under such conditions is pretty sure to be discovered sooner or later. Hence it is no wonder that many such cases are on record. They have this in common that the original plant of the variety has been found among a vast majority of representatives of the corresponding species. Nothing of course is directly known about its origin. Intermediate links have as a rule been wanting, and the seeds, which have often been sown, have not yielded reliable results, as no care was taken to preserve the blossoms from intercrossing with their parent-forms. Stress should be laid upon one feature of these curious occurrences. Relatively often the same novelty has been found twice or thrice, or even more frequently, and under conditions which make it very improbable that any relation between such occurrences might exist. The same mutation must have taken place more than once from the same main stem. The most interesting of these facts are connected with the origin of the purple beech, which [594] is now so universally cultivated. I take the following statements from an interesting historical essay of Prof. Jaggi. He describes three original localities. One is near the Swiss village, Buch am Irchel, and is located on the Stammberg. During the 17th century five purple beeches are recorded to have grown on this spot. Four of them have died, but one is still alive. Seedlings have germinated around this little group, and have been mostly dug up and transplanted into neighboring gardens. Nothing is known about the real origin of these plants, but according to an old document, it seems that about the year 1190 the purple beeches of Buch were already enjoying some renown, and attracting large numbers of pilgrims, owing to some old legend. The church of Embrach is said to have been built in connection with this legend, and was a goal for pilgrimages during many centuries. A second native locality of the purple beech is found in a forest near Sondershausen in Thuringen, Germany, where a fine group of these trees is to be seen. They were mentioned for the first time in the latter half of the eighteenth century, but must have been old specimens long before that time. The third locality seems to be of much later origin. It is a forest near Roveredo in South Tyrol, where a new [595] university is being erected. It is only a century ago that the first specimens of the purple beech were discovered there. As it is very improbable that the two last named localities should have received their purple beeches from the first named forest, it seems reasonable to assume that the variety must have been produced at least thrice. The purple beech is now exceedingly common in cultivation. But Jaggi succeeded in showing that all the plants owe their origin to the original trees mentioned above, and are, including nearly all cultivated specimens with the sole exception of the vicinity of Buch, probably derived from the trees in Thuringen. They are easily multiplied by grafting, and come true from seed, at least often, and in a high proportion. Whether the original trees would yield a pure progeny if fertilized by their own pollen has as yet not been tested. The young seedlings have purple seed-leaves, and may easily be selected by this character, but they seem to be always subjected in a large measure to vicinism. Many other instances of trees and shrubs, found in accidental specimens constituting a new variety in the wild state, might be given. The oak-leaved beech has been found in a forest of Lippe-Detmold in Germany and near Versailles, [596] whence it was introduced into horticulture by Carriere. Similarly divided and cleft leaves seem to have occurred more often in the wild state, and cut-leaved hazels are recorded from Rouen in France, birches and alders from Sweden and Lapland, where both are said to have been met with in several forests. The purple barberry was found about 1830 by Bertin, near Versailles. Weeping varieties of ashes were found wild in England and in Germany, and broom-like oaks, _Quercus pedunculata fastigiata_, are recorded from Hessen-Darmstadt, Calabria, the Pyrenees and other localities. About the real origin of all these varieties nothing is definitely known. The "single-leaved" strawberry is a variety often seen in botanical gardens, as it is easily propagated by its runners. It was discovered wild in Lapland at the time of Linnaeus, and appeared afterwards unexpectedly in a nursery near Versailles. This happened about the year 1760 and Duchesne tested it from seeds and found it constant. This strain, however, seems to have died out before the end of the 18th century. In a picture painted by Holbein (1495-1543), strawberry leaves can be seen agreeing exactly with the monophyllous type. The variety may thus be assumed to have arisen independently [597] at least thrice, at different periods and in distant localities. From all these statements and a good many others which can be found in horticultural and botanical literature, it may be inferred that mutations are not so very rare in nature as is often supposed. Moreover we may conclude that it is a general rule that they are neither preceded nor accompanied by intermediate steps, and that they are ordinarily constant from seed from the first. Why then are they not met with more often? In my opinion it is the struggle for life which is the cause of this apparent rarity; which is nothing else than the premature death of all the individuals that so vary from the common type of their species as to be incapable of development under prevailing circumstances. It is obviously without consequence whether these deviations are of a fluctuating or of a mutating nature. Hence we may conclude that useless mutations will soon die out and will disappear without leaving any progeny. Even if they are produced again and again by the same strain, but under the same unfavorable conditions, there will be no appreciable result. Thousands of mutations may perhaps take place yearly among the plants of our immediate vicinity without any chance of being discovered. [598] We are trained to the appreciation of the differentiating marks of systematic species. When we have succeeded in discerning these as given by our local flora lists, we rest content. Meeting them again we are in the habit of greeting them with their proper names. Such is the satisfaction ensuing from this knowledge that we do not feel any inclination for further inquiry. Striking deviations, such as many varietal characters, may be remarked, but then they are considered as being of only secondary interest. Our minds are turned from the delicately shaded features which differentiate elementary species. Even in the native field of the evening-primroses, no botanist would have discovered the rosettes with smaller or paler leaves, constituting the first signs of the new species. Only by the guidance of a distinct theoretical idea were they discovered, and having once been pointed out a closer inspection soon disclosed their number. Variability seems to us to be very general, but very limited. The limits however, are distinctly drawn by the struggle for existence. Of course the chance for useful mutations is a very small one. We have seen that the same mutations are as a rule repeated from time to time by the same species. Now, if a useful mutation, [599] or even a wholly indifferent one, might easily be produced, it would have been so, long ago, and would at the present time simply exist as a systematic variety. If produced anew somewhere the botanist, would take it for the old variety and would omit to make any inquiry as to its local origin. Thousands of seeds with perhaps wide circles of variability are ripened each year, but only those that belong to the existing old narrow circles survive. How different would Nature appear to us if she were free to evolve all her potentialities! Darwin himself was struck with this lack of harmony between common observations and the probable real state of things. He discussed it in connection with the cranesbill of the Pyrenees (_Geranium pyrenaicum_). He described how this fine little plant, which has never been extensively cultivated, had escaped from a garden in Staffordshire and had succeeded in multiplying itself so as to occupy a large area. In doing so it had evidently found place for an uncommonly large number of plantlets from its seeds and correspondingly it had commenced to vary in almost all organs and qualities and nearly in all imaginable directions. It displayed under these exceptional circumstances a capacity which never had been exceeded and [600] which of course would have remained concealed if its multiplication had been checked in the ordinary way. Many species have had occasion to invade new regions and cover them with hundreds of thousands of individuals. First are to be cited those species which have been introduced from America into Europe since the time of Columbus, or from Europe into this country. Some of them have become very common. In my own country the evening-primroses and Canada fleabane or are examples, and many others could be given. They should be expected to vary under these circumstances in a larger degree. Have they done so? Manifestly they have not struck out useful new characters that would enable their bearers to found new elementary species. At least none have been observed. But poor types might have been produced, and periods of mutability might have been gone through similar to that which is now under observation for Lamarck's evening primrose in Holland. From this discussion we may infer that the chances of discovering new mutating species are great enough to justify the utmost efforts to secure them. It is only necessary to observe large numbers of plants, grown under circumstances which allow the best opportunities for [601] all the seeds. And as nature affords such opportunities only at rare intervals, we should make use of artificial methods. Large quantities of seed should be gathered from wild plants and sowed under very favorable conditions, giving all the nourishment and space required to the young seedlings. It is recommended that they be sown under glass, either in a glass-house or protected against cold and rain by glass-frames. The same lot of seed will be seen to yield twice or thrice as many seedlings if thus protected, compared with what it would have produced when sown in the field or in the garden. I have nearly wholly given up sowing seeds in my garden, as circumstances can be controlled and determined with greater exactitude when the sowing is done in a glasshouse. The best proof perhaps, of the unfavorable influence of external conditions for slightly deteriorated deviations is afforded by variegated leaves. Many beautiful varieties are seen in our gardens and parks, and even corn has a variety with striped leaves. They are easily reproduced, both by buds and by seeds, and they are the most ordinary of all varietal deviations. They may be expected to occur wild also. But no real variegated species, nor even good varieties with this attribute occurs in nature. [602] On the other hand occasional specimens with a single variegated leaf, or with some few of them, are actually met with, and if attention is once drawn to this question, perhaps a dozen or so instances might be brought together in a summer. But they never seem to be capable of further evolution, or of reproducing themselves sufficiently and of repeating their peculiarity in their progeny. They make their appearance, are seen during a season, and then disappear. Even this slight incompleteness of some spots on one or two leaves may be enough to be their doom. It is a common belief that new varieties owe their origin to the direct action of external conditions and moreover it is often assumed that similar deviations must have similar causes, and that these causes may act repeatedly in the same species, or in allied, or even systematically distant genera. No doubt in the end all things must have their causes, and the same causes will lead under the same circumstances to the same results. But we are not justified in deducing a direct relation between the external conditions and the internal changes of plants. These relations may be of so remote a nature that they cannot as yet be guessed at. Therefore only direct experience may be our guide. Summing up the result of our facts and discussions [603] we may state that wild new elementary species and varieties are recorded to have appeared from time to time. Invariably this happened by sudden leaps and without intermediates. The mutants are constant when propagated by seed, and at once constitute a new race. In rare instances this may be of sufficient superiority to win a place for itself in nature, but more often it has qualities which have led to its introduction into gardens as an ornamental plant or into botanical gardens by reason of the interest afforded by their novelty, or by their anomaly. Many more mutations may be supposed to be taking place all around us, but artificial sowings on a large scale, combined with a close examination of the seedlings and a keen appreciation of the slightest indications of deviation seem required to bring them to light. [604] LECTURE XXI MUTATIONS IN HORTICULTURE It is well known that Darwin based his theory of natural selection to a large extent upon the experience of breeders. Natural and artificial selection exhibit the same general features, yet it was impossible in Darwin's time to make a critical and comparative analysis of the two processes. In accordance with our present conception there is selection of species and selection within the species. The struggle for life determines which of a group of elementary species shall survive and which shall disappear. In agricultural practice the corresponding process is usually designated by the name of variety-testing. Within the species, or within the variety, the sieve of natural selection is constantly eliminating poor specimens and preserving those that are best adapted to live under the given conditions. Some amelioration and some local races are the result, but this does not appear to be of much importance. On the contrary, the selection [605] within the race holds a prominent place in agriculture, where it is known by the imposing term, race-breeding. Experience and methods in horticulture differ from those in agriculture in many points. Garden varieties have been tested and separated for a long time, but neither vegetables nor flowers are known to exhibit such motley groups of types as may be seen in large forage crops. New varieties which appear from time to time may be ornamental or otherwise in flowers, and more or less profitable than their parents in vegetables and fruits. In either case the difference is usually striking, or if not, its culture would be unprofitable. The recognition of useful new varieties being thus made easy, the whole attention of the breeder is reduced to isolating the seeds of the mutants that are to be saved and sown separately, and this process must be repeated during a few years, in order to produce the quantity of seed that is needed for a profitable introduction of the variety into commerce. In proportion to the abundance of the harvest of each year this period is shorter for some and longer for other species. Isolation in practice is not so simple nor so easy an affair as it is in the experimental garden. Hence we have constant and nearly unavoidable [606] cross-fertilizations with the parent form or with neighboring varieties, and consequent impurity of the new strain. This impurity we have called vicinism, and in a previous lecture have shown its effects upon the horticultural races on one hand, and on the other, on the scientific value that can be ascribed to the experience of the breeder. We have established the general rule that stability is seldom met with, but that the observed instability is always open to the objection of being the result of vicinism. Often this last agency is its sole cause; or it may be complicated with other factors without our being able to discern them. Though our assertion that the practice of the horticulturist in producing new varieties is limited to isolation, whenever chance affords them, is theoretically valid, it is not always so. We may discern between the two chief groups of varieties. The retrograde varieties are constant, the individuals not differing more from one another than those of any ordinary species. The highly variable varieties play an important part in horticulture. Double flowers, striped flowers, variegated leaves and some others yield the most striking instances. Such forms have been included in previous lectures among the ever-sporting varieties, because their peculiar characters oscillate between two extremes, viz: [607] the new one of the variety and the corresponding character of the original species. In such cases isolation is usually accompanied by selection: rarely has the first of a double, striped or variegated race well filled or richly striped flowers or highly spotted leaves. Usually minor degrees of the anomaly are seen first, and the breeder expects the novelty to develop its features more completely and more beautifully in subsequent generations. Some varieties need selection only in the beginning, in others the most perfect specimens must be chosen every year as seed-bearers. For striped flowers, it has been prescribed by Vilmorin, that seeds should be taken only from those with the smallest stripes, because there is always reversion. Mixed seed or seed from medium types would soon yield plants with too broad stripes, and therefore less diversified flowers. In horticulture, new varieties, both retrograde and ever-sporting, are known to occur almost yearly. Nevertheless, not every novelty of the gardener is to be considered as a mutation in the scientific sense of the word. First of all, the novelties of perennial and woody species are to be excluded. Any extreme case of fluctuating variability may be preserved and multiplied in the vegetative way. Such types are designated [608] in horticulture as varieties, though obviously they are of quite another nature than the varieties reproduced by seed. Secondly, a large number, no doubt the greater number of novelties, are of hybrid origin. Here we may discern two cases. Hybrids may be produced by the crossing of old types, either of two old cultivated forms or newly introduced species, or ordinarily between an old and an introduced variety. Such novelties are excluded from our present discussion. Secondly, hybrids may be produced between a true, new mutation and some of the already existing varieties of the same species. Examples of this obvious and usual practice will be given further on, but it must be pointed out now that by such crosses a single mutation may produce as many novelties as there are available varieties of the same species. Summarizing these introductory remarks we must lay stress on the fact that only a small part of the horticultural novelties are real mutations, although they do occur from time to time. If useful, they are as a rule isolated and multiplied, and if necessary, improved by selection. They are in many instances, as constant from seed as the unavoidable influence of vicinism allows them to be. Exact observations on the origin, or on the degree of constancy, are usually lacking, [609] the notes being ordinarily made for commercial purposes, and often only at the date of introduction into trade, when the preceding stages of the novelty may have been partly forgotten. With this necessary prelude I will now give a condensed survey of the historical facts relating to the origin of new horticultural varieties. An ample description has been given recently by Korshinsky, a Russian writer, who has brought together considerable historical material as evidence of the sudden appearance of novelties throughout the whole realm of garden plants. The oldest known, and at the same time one of the most accurately described mutations is the origin of the cut-leaved variety of the greater celandine or _Chelidonium majus_. This variety has been described either as such, or as a distinct species, called _Chelidonium laciniatum_ Miller. It is distinguished from the ordinary species, by the leaves being cut into narrow lobes, with almost linear tips, a character which is, as we have seen on a previous occasion, repeated in the petals. It is at present nearly as commonly cultivated in botanical gardens as the _C. majus_, and has escaped in many localities and is observed to thrive as readily as the native wild [610] plants. It was not known until a few years before the close of the 16th century. Its history has been described by the French botanist, Rose. It was seen for the first time in the garden of Sprenger, an apothecary of Heidelberg, where the _C. majus_ had been cultivated for many years. Sprenger discovered it in the year 1590, and was struck by its peculiar and sharply deviating characters. He was anxious to know whether it was a new plant and sent specimens to Clusius and to Plater, the last of whom transmitted them to Caspar Bauhin. These botanists recognized the type as quite new and Bauhin described it some years afterwards in his Phytopinax under the name of _Chelidonium majus foliis quernis_, or oak-leaved celandine. The new variety soon provoked general interest and was introduced into most of the botanical gardens of Europe. It was recognized as quite new, and repeated search has been made for it in a wild state, but in vain. No other origin has been discovered than that of Sprenger's garden. Afterwards it became naturalized in England and elsewhere, but there is not the least doubt as to its derivation in all the observed cases. Hence its origin at Heidelberg is to be considered as historically proven, and it is of course only legitimate to assume that it originated in [611] the year 1590 from the seeds of the _C. majus_. Nevertheless, this was not ascertained by Sprenger, and some doubt as to a possible introduction from elsewhere might arise. If not, then the mutation must have been sudden, occurring without visible preparation and without the appearance of intermediates. From the very first, the cut-leaved celandine has been constant from seed. Or at least it has been propagated by seed largely and without difficulty. Nothing, however, is known about it in the first few years of its existence. Later careful tests were made by Miller, Rose and others and later by myself, which have shown its stability to be absolute and without reversion, and it has probably been so from the beginning. The fact of its constancy has led to its specific distinction by Miller, as varieties were in his time universally, and up to the present time not rarely, though erroneously, believed to be less stable than true species. Before leaving the laciniate celandine it is to be noted that in crosses with _C. majus_ it follows the law of Mendel, and for this reason should be considered as a retrograde variety, the more so, as it is also treated as such from a morphological point of view by Stahl and others. We now come to an enumeration of those cases in which the date of the first appearance [612] of a new horticultural variety has been recorded, and I must apologize for the necessity of again quoting many variations, which have previously been dealt with from another point of view. In such cases I shall limit myself as closely as possible to historical facts. They have been recorded chiefly by Verlot and Carriere, who wrote in Paris shortly after the middle of the past century, and afterwards by Darwin, Korshinsky, and others. It is from their writings and from horticultural literature at large that the following evidence is brought together. A very well-known instance is that of the dwarf variety of _Tagetes signata_, which arose in the nursery of Vilmorin in the year 1860. It was observed for the first time in a single individual among a lot of the ordinary _Tagetes signata_. It was found impossible to isolate it, but the seeds were saved separately. The majority of the offspring returned to the parental type, but two plants were true dwarfs. From these the requisite degree of purity for commercial purposes was reached, the vicinists not being more numerous than 10% of the entire number. The same mutation had been observed a year earlier in the same nursery in a lot of _Saponaria calabrica_. The seeds of this dwarf repeated the variety in the next generation, but in the third none were observed. Then the variety was [613] thought to be lost, and the culture was given up, as the Mendelian law of the splitting of varietal hybrids was not known. According to our present knowledge we might expect the atavistic descendants of the first dwarf to be hybrids, and to be liable to split in their progeny into one-fourth dwarfs and three-fourths normal specimens. From this it is obvious that the dwarfs would have appeared a second time if the strain had been continued by means of the seeds of the vicinistic progeny. In order to avoid a return to this phase of the question, another use of the vicinists should at once be pointed out. It is the possibility of increasing the yield of the new variety. If space admits of sowing the seeds of the vicinists, a quarter of the progeny may be expected to come true to the new type, and if they were partly pollinated by the dwarfs, even a larger number would do so. Hence it should be made a rule to sow these seeds also, at least when those of the true representatives of the novelty do not give seed enough for a rapid multiplication. Other dwarfs are recorded to have sprung from species in the same sudden and unexpected manner, as for instance _Ageratum coeruleum_ of the same nursery, further _Clematis Viticella nana_ and _Acer campestre nanum_. _Prunus Mahaleb nana_ was discovered in 1828 in one [614] specimen near Orleans by Mme. LeBrun in a large culture of Mahaleb. _Lonicera tatarica nana_ appeared in 1825 at Fontenay-aux Roses. A tall variety of the strawberry is called "Giant of Zuidwijk" and originated at Boskoop in Holland in the nursery of Mr. van de Water, in a lot of seedlings of the ordinary strawberry. It was very large, but produced few runners, and was propagated with much difficulty, for after six years only 15 plants were available. It proved to be a late variety with abundant large fruit, and was sold at a high price. For a long time it was prominent in cultures in Holland only. Varieties without prickles are known to have originated all of a sudden in sundry cases. _Gleditschia sinensis_, introduced in 1774 from China, gave two seedlings without spines in the year 1823, in the nursery of Caumzet. It is curious in being one of the rare instances where a simultaneous mutation in two specimens is acknowledged, because as a rule, such records comply with the prevailing, though inexact, belief that horticultural mutations always appear in single individuals. From Korshinsky's survey of varieties with cut leaves or laciniate forms the following cases may be quoted. In the year 1830 a nurseryman named Jacques had sown a large lot of elms, [615] _Ulmus pedunculata_. One of the seedlings had cut leaves. He multiplied it by grafting and gave it to the trade under the name of _U. pedunculata urticaefolia_. It has since been lost. Laciniate alders seem to have been produced by mutation at sundry times. Mirbel says that the _Alnus glutinosa laciniata_ is found wild in Normandy and in the forests of Montmorency near Paris. A similar variety has been met with in a nursery near Orleans in the year 1855. In connection with this discovery some discussion has arisen concerning the question whether it was probable that the Orleans strain was a new mutation, or derived in some way from the trees cited by Mirbel. Of course, as always in such cases, any doubt, once pronounced, affects the importance of the observation for all time, since it is impossible to gather sufficient historical evidence to fully decide the point. The same variety had appeared under similar circumstances in a nursery at Lyons previously (1812). Laciniated maples are said to be of relatively frequent occurrence in nurseries, among seedlings of the typical species. Loudon says that once 100 laciniated seedlings were seen to originate from seed of some normal trees. But in this case it is rather probable that the presumed [616] normal parents were in reality hybrids between the type and the laciniated form, and simply split according to Mendel's law. This hypothesis is partly founded on general considerations and partly on experiments made by myself with the cut-leaved celandine, previously alluded to, which I crossed with the type. The hybrids repeated the features of the species and showed no signs of their internal hybrid constitution. But the following year one-fourth of their progeny returned to the cut-leaved form. If the same thing has taken place in the case of Loudon's maples, but without their hybrid origin being known, the result would have been precisely what he observed. _Broussonetia papyriffera dissecta_ originated about 1830 at Lyons, and a second time in 1866 at Fontenay-aux-Roses. The cut-leaved hazelnuts, birches, beeches and others have mostly been found in the wild state, as I have already pointed out in a previous lecture. A similar variety of the elder, _Sambucus nigra laciniata_, and its near ally, _Sambucus racemosa laciniata_, are often to be seen in our gardens. They have been on record since 1886 and come true from seed, but their exact origin seems to have been forgotten. Cut-leaved walnuts have been known since 1812; they come true from seed, but are extremely liable to vicinism, a nuisance which is [617] ascribed by some authors to the fact that often on the same tree the male catkins flower and fall off several weeks before the ripening of the pistils of the other form of flowers. Weeping varieties afford similar instances. _Sophora japonica pendula_ originated about 1850, and _Gleditschia triacanthos pendula_ some time later in a nursery at Chateau-Thierry (Aisne, France). In the year 1821 the bird's cherry, or _Prunus Padus_, produced a weeping variety, and in 1847 the same mutation was observed for the allied _Prunus Mahaleb_. Numerous other instances of the sudden origin of weeping trees, both of conifers and of others, have been brought together in Korshinsky's paper. This striking type of variation includes perhaps the best examples of the whole historical evidence. As a rule they appear in large sowings, only one, or only a few at a time. Many of them have not been observed during their youth, but only after having been planted out in parks and forests, since the weeping characters show only after several years. The monophyllous bastard-acacia originated in the same way. Its peculiarities will be dealt with on another occasion, but the circumstances of its birth may as well be given here. In 1855 in the nursery of Deniau, at Brain-sur-l'Authion (Maine et Loire), it appeared in a lot of [618] seedlings of the typical species in a single individual. This was transplanted into the Jardin des Plantes at Paris, where it flowered and bore seeds in 1865. It must have been partly pollinated by the surrounding normal representatives of the species, since the seeds yielded only one-fourth of true offspring. This proportion, however, has varied in succeeding years. Briot remarks that the monophyllous bastard acacia is liable to petaloid alterations of its stamens, which deficiency may encroach upon its fertility and accordingly upon the purity of its offspring. Broom-like varieties often occur among trees, and some are known for their very striking reversions by buds, as we have seen on a previous occasion. They are ordinarily called pyramidal or fastigiate forms, and as far as their history goes, they arise suddenly in large sowings of the normal species. The fastigiate birch was produced in this way by Baumann, the _Abies concolor fastigiata_ by Thibault and Keteleer at Paris, the pyramidal cedar by Paillat, the analogous form of _Wellingtonia_ by Otin. Other instances could easily be added, though of course some of the most highly prized broom-like trees are so old that nothing is known about their origin. This, for instance, is the case with the pyramidal yew-tree, _Taxus baccata fastigiata_. [619] Others have been found wild, as already mentioned in a former lecture. An analogous case is afforded by the purpleleaved plums, of which the most known form is Prunus Pissardi. It is said to be a purple variety of _Prunus cerasifera_, and was introduced at the close of the seventies from Persia, where it is said to have been found in Tabris. A similar variety arose independently and unexpectedly in the nursery of Spath, near Berlin, about 1880, but it seems to differ in some minor points from the Persian prototype. A white variety of _Cyclamen vernum_ made its appearance in the year 1836 in Holland. A single individual was observed for the first time among a large lot of seedlings, in a nursery near Haarlem. It yielded a satisfactory amount of seed, and the progeny was true to the new type. Such plants propagate slowly, and it was only twenty-seven years later (1863) that the bulbs were offered for sale by the Haarlem firm of Krelage & Son. The price of each bulb was $5.00 in that year, but soon afterwards was reduced to $1.00 each, which was about thrice the ordinary price of the red variety. The firm of Messrs. Krelage & Son has brought into commerce a wide range of new bulb-varieties, all due to occasional mutations, some by seed and others by buds, or to the accidental [620] transference of new qualities into the already existing varieties by cross-pollination through the agency of insects. Instead of giving long lists of these novelties, I may cite the black tulips, which cost during the first few years of their introduction about $25.00 apiece. Horticultural mutations are as a rule very rare, especially in genera or species which have not yet been brought to a high degree of variability. In these the wide range of varieties and the large scale in which they are multiplied of course give a greater chance for new varieties. But then the possibilities of crossing are likewise much larger, and apparent changes due to this cause may easily be taken for original mutations. The rarity of the mutations is often proved by the lapse of time between the introduction of a species and its first sport. Some instances may be given. They afford a proof of the length of the period during which the species remained unaltered, although some of these alterations may be due to a cross with an allied form. _Erythrina Crista-galli_ was introduced about 1770, and produced its first sport in 1884, after more than a century of cultivation. _Begonia semperflorens_ has been cultivated since 1829, and for half a century before it commenced sporting. The same length of time has elapsed [621] between the first culture and the first variation of _Crambe maritima_. Other cases are on record in which the variability exhibited itself much sooner, perhaps within a few years after the original discovery of the species. But such instances seem, as a rule, to be subject to doubt as to the concurrence of hybridization. So for instance the _Iris lortetii_, introduced in the year 1895 from the Lebanon, which produced a white variety from its very first seeds. If by chance the introduced plants were natural hybrids between the species and the white variety, this apparent and rather improbable mutation would find a very simple explanation. The length of the period preceding the first signs of variability is largely, of course, due to divergent methods of culture. Such species as _Erythrina_, which are perennial and only sown on a small scale, should not be expected to show varieties very soon. Annual species, which are cultivated yearly in thousands or even hundreds of thousands of individuals, have a much better chance. Perhaps the observed differences are largely due to this cause. Monstrosities have, from time to time, given rise to cultivated races. The cockscomb or _Celosia_ is one of the most notorious instances. Cauliflowers, turnips and varieties of cabbages are recorded by De Candolle to have arisen in [622] culture, more than a century ago, as isolated monstrous individuals. They come true from seed, but show deviations from time to time which seem to be intimately linked with their abnormal characters. Apetalous flowers may be considered as another form of monstrosity, and in _Salpiglossis sinuata_ such a variety without a corolla made its appearance in the year 1892 in the nursery of Vilmorin. It appeared suddenly, yielded a good crop of seed and was constant from the outset, without any sign of vicinism or impurity. In several cases the origin of a variety is obscure, while the subsequent historical evidence is such as to make an original sudden appearance quite probable. Although these instances offer but indirect evidence, and will sooner or later lose their importance, it seems desirable to lay some stress on them here, because most of these cases are very obvious and more striking than purely historical facts. Sterile varieties belong to this heading. Sometimes they bear fruit without kernels, sometimes flowers without sexual organs, or even no flowers at all. Instances have been given in the lecture on retrograde varieties; they are ordinarily assumed to have originated by a leap, because it is not quite clear how a loss of the capacity for the formation of seeds could have been slowly accumulated [623] in preceding generations. An interesting case is afforded by a sterile variety of corn, which originated some time ago in my own pedigree-cultures made for another purpose, and which had begun with an ear of 1886. The first generation from the original seeds showed nothing particular, but the second at once produced quite a number of sterile plants. The sterility was caused by the total lack of branches, including those bearing the pistillate flowers. The terminal spikes themselves were reduced to naked spindles, without branches, without flowers and even almost without bracts. In some individuals, however, this negative character was seen to give way at the tip, showing a few small naked branches. Of course it was impossible to propagate this curious form, but my observations showed that it sprang into existence from known ancestors by a single step or sudden leap. This leap, however, was not confined to a single specimen; on the contrary it affected 40 plants out of a culture of 340 individuals. The same phenomenon was repeated from the seeds of the normal plants in the following year, but afterwards the monstrosity disappeared. The Italian poplar affords another instance. It is considered by some authors as a distinct species, _Populus italica_, and by others as a [624] broom-like variety of the _Populus nigra_, from which it is distinguished by its erect branches and other characters of minor importance. It is often called the pyramidal or fastigiate poplar. Its origin is absolutely unknown and it occurs only in the cultivated state. In Italy it seems to have been cultivated from the earliest historical times, but it was not introduced into other countries till the eighteenth century. In 1749 it was brought into France, and in 1758 into England, and to day it may be seen along roads throughout central Europe and in a large part of Asia. But the most curious fact is that it is only observed in staminate specimens; pistillate trees have not been found, although often sought for. This circumstance makes it very probable that the origin of the broom-like poplar was a sudden mutation, producing only one individual. This being staminate, it has been propagated exclusively by cuttings. It is to be admitted, however, that no material evidence is at hand to prove that it is not an original wild species, the pistillate form of which has been lost by vegetative multiplication. One form only of many dioecious plants is to be found in cultivation, as, for instance some South American species of _Ribes_. Total lack of historical evidence concerning [625] the origin of a variety has sometimes been considered as sufficient proof of a sudden origin. The best known instance is that of the renowned cactus-dahlia with its recurved instead of incurved ray-florets. It was introduced from Mexico into the Netherlands by Van den Berg of Jutphaas, under the following remarkable circumstances. In the autumn of 1872 one of his friends had sent him a small case, containing seeds, bulbs and roots from Mexico. From one of these roots a _Dahlia_ shoot developed. It was cultivated with great care and bloomed next year. It surprised all who saw it by the unexpected peculiarity of its large rich crimson flowers, the rays of which were reversed tubular. The margins of the narrow rays were curved backwards, showing the bright color of the upper surface. It was a very showy novelty, rapidly multiplied by cuttings, and was soon introduced into commerce. It has since been crossed with nearly all other available varieties of the _Dahlia_, giving a large and rich group of forms, bound together by the curious curling of the petals. It has never been observed to grow in Mexico, either wild or in gardens, and thus the introduced individual has come to be considered as the first of its race. I have already mentioned that the rapid production of large numbers of new varieties, by [626] means of the crossing of the offspring of a single mutant with previously existing sorts, is a very common feature in horticultural practice. It warns us that only a small part of the novelties introduced yearly are due to real mutations. Further instances of novelties with such a common origin are the purple-leaved dahlias, the gooseberries without prickles, the double petunias, erect gloxinias and many others. Accumulation of characters, acquired in different races of a species, may easily be effected in this way; in fact it is one of the important factors in the breeding of horticultural novelties. I have alluded more than once in this lecture to the question, whether it is probable that mutations occur in one individual or in more. The common belief among horticulturists is that, as a rule, they appear in a single plant. This belief is so widespread that whenever a novelty is seen for the first time in two or more specimens it is at once suggested that it might have originated and been overlooked in a previous generation. Not caring to confess a lack of close observation, the number of mutants in such cases is usually kept secret. At least this statement has been made to me by some of the horticulturists at Erfurt, whom I visited some years ago in order to learn as much as [627] possible about the methods of production of their novelties. Hence it is simply impossible to decide the question on the basis of the experience of the breeders. Even in the case of the same novelty arising in sundry varieties of the same species, the question as to common origin, by means of crossing, is often hard to decide, as for instance in moss-roses and nectarines. On the other hand, instances are on record where the same novelty has appeared at different times, often at long intervals. Such is the case with the butterfly-cyclamen, a form with wide-spreading petals which originated in Martin's nursery in England. The first time it was seen it was thought to be of no value, and was thrown away, but when appearing for a second time it was multiplied and eventually placed on the market. Other varieties of _Cyclamen_, as for instance the crested forms, are also known to have originated repeatedly. In concluding this series of examples of horticultural mutations, I might mention two cases, which have occurred in my own experimental garden. The first refers to a tubular _Dahlia_. It has ray-florets, the ligules of which have their margins grown together so as to form tubes, with the outer surface corresponding to the pale under-surface of the corolla. This novelty originated in a single plant in a [628] culture from the seed of the dwarf variety "Jules Chretien." The seeds were taken from introduced plants in my garden, and as the sport has no ornamental value it is uncertain whether this was the first instance or whether it had previously occurred in the nursery at Lyons, from whence the bulbs were secured. Afterwards it proved true from seed, but was very variable, exhibiting rather the features of an ever-sporting variety. Another novelty was seen the first time in several individuals. It was a pink sport of the European cranesbill, _Geranium pratense_. It arose quite unexpectedly in the summer of 1902 from a striped variety of the blue species. It was seen in seven specimens out of a lot of about a hundred plants. This strain was introduced into my garden in 1897, when I bought two plants under the name of _Geranium pratense album_, which however proved to belong to the striped variety. From their seeds I sowed in 1898 a first generation, of which a hundred plants flowered the next year, and from their seeds I sowed in 1900 the lot which produced the sport. Neither the introduced plants nor their offspring had exhibited the least sign of a color-variation, besides the blue and white stripes. Hence it is very probable that my novelty was a true first mutation, the more probably [629] so since a pink variety would without doubt have a certain horticultural value and would have been preserved if it had occurred. But as far as I have been able to ascertain, it is as yet unknown, nor has it been described until today. Summing up the results of this long, though very incomplete, list of horticultural novelties with a more or less well-known origin, we see that sudden appearances are the rule. Having once sprung into existence the new varieties are ordinarily constant, except as affected by vicinism. Details concerning the process are mostly unavailable or at least are of very doubtful value. And to this it should be added that really progressive mutations have hardly been observed in horticulture. Hence the theoretical value of the facts is far less than might have been expected. [630] LECTURE XXII SYSTEMATIC ATAVISM The steady cooperation of progression and retrogression is one of the important principles of organic evolution. I have dwelt upon this point more than once in previous lectures. I have tried to show that both in the more important lines of the general pedigree of the vegetable kingdom, and in the numerous lateral branches ending in the genera and species within the families, progression and retrogression are nearly always at work together. Your attention has been directed to the monocotyledons as an example, where retrogression is everywhere so active that it can almost be said to be the prevailing movement. Reduction in the vegetative and generative organs, in the anatomical structure and growth of the stems, and in sundry other ways is the method by which the monocotyledons have originated as a group from their supposed ancestors among the lower dicotyledonous families. Retrogression is the leading idea in the larger families of the group, [631] as for instance in the aroids and the grasses. Retrograde evolution is also typical in the highest and most highly differentiated family of the monocotyledons, the orchids, which have but one or two stamens. In the second place I have had occasion more than once to assert that retrogression, though seemingly consisting in the disappearance of some quality, need not, as a rule, be considered as a complete loss. Quite on the contrary, it is very probable that real losses are extremely rare, if not wholly lacking. Ordinarily the loss is only apparent, the capacity becomes inactive only, but is not destroyed. The character has become latent, as it is commonly stated, and therefore may return to activity and to the full display of its peculiarity, whenever occasion offers. Such a return to activity was formerly called atavism. But as we have seen, when dealing with the phenomena of latency at large, sundry cases of latency are to be distinguished, in order to get a clear insight into these difficult processes. So it is with atavism, too. If any plant reverts to a known ancestor, we have a positive and simple case. But ancestors with alternate specific marks are as a rule neither historically nor experimentally manifest. They are only reputed to be such, and the presumption rests [632] upon the systematic affinity between the derivative species and its nearest probable allies. Such reversions are now to be examined at some length and may be adequately treated under the head of systematic atavism. To this form of atavism pertain, on the basis of our definition, those phenomena by which species assume one or more characters of allies, from which they are understood to have descended by the loss of the character under discussion. The phenomena themselves consist in the production of anomalies and varieties, and as the genetic relation of the latter is often hardly beyond doubt, the anomalies seem to afford the best instances for the study of systematic atavism. This study has for its chief aim the demonstration of the presence of the latent characters, and to show that they return to activity suddenly and not by a slow and gradual recovery of the former features. It supports the assertion that the visible elementary characters are essentially an external display of qualities carried by the bearers of heredity, and that these bearers are separate entities, which may be mingled together, but are not fused into a chaotic primitive life-substance. Systematic atavism by this means leads us to a closer examination of the internal and concealed causes, which rule the affinities and divergencies of [633] allied species. It brings before us and emphasizes the importance of the conception of the so-called unit-characters. The primrose will serve as an example. In the second lecture we have seen that the old species of Linnaeus, the _Primula veris_, was split up by Jacquin into three smaller ones, which are called _P. officinalis_, _P. elatior_ and _P. acaulis_. From this systematic treatment we can infer that these three forms are assumed to be derived from a common ancestor. Now two of them bear their flowers in bracted whorls, condensed into umbels at the summits of a scape. The scapes themselves are inserted in the axils of the basal leaves, and produce the flowers above them. In the third species, _Primula acaulis_, this scape is lacking and the flowers are inserted singly in the axils on long slender stalks. For this reason the species is called acaulescent, indicating that it has no other stem than the subterranean rootstock. But on closer inspection we observe that the flower stalks are combined into little groups, each group occupying the aril of one of the basal leaves. This fact at once points to an analogy with the umbellate allies, and induces us to examine the insertion of the flowers more critically. In doing so we find that they are united at their base so as to constitute a sessile umbel. [634] The scapes are not absolutely lacking, but only reduced to almost invisible rudiments. Relying upon this conclusion we infer that all of the three elementary species have umbels, some pedunculate and the others not. On this point they agree with the majority of the allied species in the genus and in other genera, as for instance in _Androsace_. Hence the conclusion that the common ancestors were perennial plants with a rootstock bearing their flowers in umbels or whorls on scapes. Lacking in the _Primula veris_, these scapes must obviously have been lost at the time of the evolution of this form. Proceeding on this line of speculation we at once see that a very adequate opportunity for systematic atavism is offered here. According to our general conception the apparent loss of a scape is no proof of a corresponding internal loss, but might as well be caused simply by the reduction of the scape-growing capacity to a latent or inactive state. It might be awakened afterwards by some unknown agency, and return to activity. Now this is exactly what happens from time to time. In Holland the acaulescent primrose is quite a common plant, filling the woods in the spring with thousands of clusters of bright yellow flowers. It is a very uniform type, but in [635] some years it is seen to return to atavistic conditions in some rare individuals. More than once I have observed such cases myself, and found that the variation is only a partial one, producing one or rarely two umbels on the same plant, and liable to fail of repetition when the varying specimens are transplanted into the garden for further observation. But the fact remains that scapes occur. The scapes themselves are of varying length, often very short, and seldom long, and their umbels display the involucre of bracts in a manner quite analogous to that of the _Primula officinalis_ and _P. elatior_. To my mind this curious anomaly strongly supports the view of the latent condition of the scape in the acaulescent species, and that such a dormant character must be due to a descent from ancestors with active scapes, seems to be in no need of further reiteration. Returning to activity the scapes at once show a full development, in no way inferior to that of the allied forms, and only unstable in respect to their length. A second example is afforded by the bracts of the crucifers. This group is easily distinguished by its cruciform petals and the grouping of the flowers into long racemes. In other families each flower of such an inflorescence would be subtended by a bract, according to the [636] general rule that in the higher plants side branches are situated in the arils of leaves. Bracts are reduced leaves, but the spikes of the cruciferous plants are generally devoid of them. The flower-stalks, with naked bases, seem to arise from the common axis at indefinite points. Hence the inference that crucifers are an exception to a general rule, and that they must have originated from other types which did comply with this rule, and accordingly were in the possession of floral bracts. Or, in other words, that the bracts must have been lost during the original evolution of the whole family. This conclusion being accepted, the accidental re-apparition of bracts within the family must be considered as a case of systematic atavism, quite analogous to the re-appearance of the scapes in the acaulescent primrose. The systematic importance of this phenomenon, however, is far greater than in the first case, in which we had only to deal with a specific character, while the abolition of the bracts has become a feature of a whole family. This reversion is observed to take place according to two widely different principles. On one hand, bracts may be met with in a few stray species, assuming the rank of a specific character. On the other hand they may be seen [637] to occur as an anomaly, incompletely developed, often very rare and with all the appearance of an accidental variation, but sometimes so common as to seem nearly normal. Coming now to particular instances, we may turn our attention in the first place to the genus _Sisymbrium_. This is a group of about 50 species, of wide geographic distribution, among which the hedge mustard (_S. officinalis_) is perhaps the most common of weeds. Two species are reputed to have bracts, _Sisymbrium hirsutum_ and _S. supinum_. Each flower-stalk of their long racemes is situated in the aril of such a bract, and the peculiarity is quite a natural one, corresponding exactly to what is seen in the inflorescence of other families. Besides the _Sisymbrium some six other genera afford similar structures. _Erucastrum pollichii_ has been already alluded to in a former lecture when dealing with the same problem from another point of view. As previously stated, it is one of the most manifest and most easily accessible examples of a latent character becoming active through systematic atavism. In fact, its bracts are found so often as to be considered by some authors as of quite normal occurrence. Contrasted with those of the above mentioned species of _Sisymbrium_, they are not seen at the base of all the flower [638] stalks, but are limited to the lowermost part of the raceme, adorning a few, often ten or twelve, and rarely more flower-stalks. Moreover they exhibit a feature which is indicative of the presence of an abnormality. They are not all of the same size, but decrease in length from the base of the raceme upward, and finally slowly disappear. Besides these rare cases there are quite a number of cruciferous species on record, which have been observed to bear bracts. Penzig in his valuable work on teratology gives a list of 33 such genera, many of them repeating the anomaly in more than one species. Ordinary cabbages are perhaps the best known instance, and any unusual abundance of nourishment, or anomalous cause of growth seems to be liable to incite the development of bracts. The hedge garlic or garlic mustard (_Alliaria_), the shepherd's purse, the wormseed or _Erysimum cheiranthoides_ and many others afford instances. In my cultures of Heeger's shepherd's purse, the new species derived at Landau in Germany from the common shepherd's purse, the anomaly was observed to occur more than once, showing that the mutation, which changed the fruits, had not in the least affected this subordinate anomalous peculiarity. In all these cases the bracts behave as with the Erucastrum, [639] being limited to the base of the spike, and decreasing in size from the lower flowers upward. Connected with these atavistic bracts is a feature of minor importance, which however, by its almost universal accompaniment of the bracts, deserves our attention, as it is indicative of another latent character. As a rule, the bracts are grown together with their axillary flower-stalk. This cohesion is not complete, nor is it always developed in the same degree. Sometimes it extends over a large part of the two organs, leaving only their tips free, but on other occasions it is limited to a small part of the base. But it is very interesting that this same cohesion is to be seen in the shepherd's purse, in the wormseed and in the cabbage, as well as in the case of the _Erucastrum_ and most of the other observed cases of atavistic bracts. This fact suggests the idea of a common origin for these anomalies, and would lead to the hypothesis that the original ancestors of the whole family, before losing the bracts, exhibited this peculiar mode of cohesion. Bracts and analogous organs afford similar cases of systematic atavism in quite a number of other families. Aroids sometimes produce long bracts from various places on their spadix, as may be seen in the cultivated greenhouse species, _Anthurium scherzerianum_. [640] Poppies have been recorded to bear bracts analogous to the little scales on the flower-stalks of the pansies, on the middle of their flower stalks. A similar case is shown by the yellow foxglove or _Digitalis parviflora_. The foxgloves as a rule have naked flower-stalks, without the two little opposite leafy organs seen in so many other instances. The yellow species, however, has been seen to produce such scales from time to time. The honeysuckle genus is, as a rule, devoid of the stipules at the base of the petiole, but _Lonicera etrusca_ has been observed to develop such organs, which were seen to be free in some, but in other specimens were adnate to the base of the leaf, and even connate with those of the opposite leaf. Other instances could be given proving that bracts and stipules, when systematically lacking, are liable to reappear as anomalies. In doing so, they generally assume the peculiar characters that would be expected of them by comparison with allied genera in which they are of normal occurrence. There can be no doubt that their absence is due to an apparent loss, resulting from the reduction of a formerly active quality to inactivity. Resuming this effective state, the case attains the value and significance accorded to systematic atavism. A very curious instance of reduced bracts, developing [641] to unusual size, is afforded by a variety of corn, which is called _Zea Mays cryptosperma_, or _Zea Mays tunicata_. In ordinary corn the kernels are surrounded by small and thin, inconspicuous and membranaceous scales. Invisible on the integrate spikes, when ripe, they are easily detected by pulling the kernels out. In _cryptosperma_ they are so strongly developed as to completely hide the kernels. Obviously they constitute a case of reversion to the characters of some unknown ancestor, since the corn is the only member of the grass-family with naked kernels. The var. _tunicata_, for this same reason, has been considered to be the original wild form, from which the other varieties of corn have originated. But as no historical evidence on this point is at hand, we must leave it as it is, notwithstanding the high degree of attractiveness attached to the suggestion. The horsetail-family may be taken as a further support of our assertion. Some species have stems of two kinds, the fertile being brownish and appearing in early spring before the green or sterile ones. In others the stems are all alike, green and crowned with a conelike spike of sporangia-bearing scales. Manifestly the dimorphous cases are to be considered as the younger ones, partly because they are obvious exceptions to the common rule, and [642] partly because the division of labor is indicative of a higher degree of evolution. But sometimes these dimorphic species are seen to revert to the primary condition, developing a fertile cone at the summit of the green summer-stem. I have had the opportunity of collecting an instance of this anomaly on the tall _Equisetum telmateja_ in Switzerland, and other cases are on record in teratological literature. It is an obvious example of systematic atavism, occurring suddenly and with the full development of all the qualities needed for the normal production of sporangia and spores. All of these must be concealed in a latent condition within the young tissues of the green stems. More than once I have had occasion to deal with the phenomenon of torsions, as exhibited by the teasels and some other plants. This anomaly has been shown to be analogous to the cases described as double adaptations. The capacity of evolving antagonistic characters is prominent in both. The antagonists are assumed to lie quietly together while inactive. But as soon as evolution calls them into activity they become mutually exclusive, because only one of them can come to full display in the same organ. External influences decide which of the two becomes dominant and which remains dormant. This decision must take place separately [643] for each stem and each branch, but as a rule, the stronger ages are more liable to furnish anomalies than the weaker. Exactly the same thing is true of double adaptations. Every bud of the water-persicaria may develop either into an erect or into a floating stem, according as it is surrounded by water or by relatively dry soil. In other cases utility is often less manifest, but some use may either be proved, or shown to be very probable. At all events the term adaptation includes the idea of utility, and obviously useless contrivances could hardly be brought under the same head. We have also dealt with the question of heredity. It is obvious that from the flowers of the floating and erect stems of the water-persicaria seeds will result, each capable of yielding both forms. Quite the same thing was the case with the teasels. Some 40% of the progeny produce beautifully twisted stems, but whether the seed was saved from the most completely twisted specimens or from the straight plants of the race was of no importance. This phenomenon of twisting may now be considered from quite another point of view. It is a case of systematic atavism, or of the reacquirement of some ancient and long-lost quality. This quality is the alternate position of [644] the leaves, which has been replaced in the teasel family by a grouping in pairs. In order to prove the validity of this assertion, it will be necessary to discuss two points separately, viz.: relative positions of the leaves, and the manner in which the alternate position causes the stems to become twisted. Leaves are affixed to their stems and branches in various ways. Among them one is of wide occurrence throughout the whole realm of the higher plants, while all the others are more rare. Moreover these subordinate arrangements are, as a rule, confined to definite systematic groups. Such groups may be large, as for instance, the monocotyledons, that have their leaves arranged in two opposite rows in many families, or small, as genera or subdivisions of genera. Apart from these special cases the main stem and the greater part of the branches of the pedigree of the higher plants exhibit a spiral condition or a screw arrangement, all leaves being inserted at different points and on different sides of the stem. This condition is assumed to be the original one, from which the more specialized types have been derived. As is usual with characters in general, it is seen to vary around an average, the spiral becoming narrower and looser. A narrow spiral condenses the leaves, while a [645] loose one disperses them. According to such fluctuating deviations the number of leaves, inserted upon a given number of spiral circuits, is different in different species. In a vast majority of cases 13 leaves are found on 5 circuits, and as we have only to deal with this proportion in the teasels we will not consider others. In the teasels this screw-arrangement has disappeared, and has been replaced by a decussate grouping. The leaves are combined into pairs, each pair occupying the opposite sides of one node. The succeeding pairs alternate with one another, so as to place their leaves at right angles. The leaves are thus arranged on the whole stem in four equidistant rows. On the normal stem of a teasel the two members of a pair are tied to one another in a comparatively complicated way. The leaves are broadly sessile and their bases are united so as to constitute a sort of cup. The margins of these cups are bent upward, thereby enabling them to hold water, and after a rainfall they may be seen filled to the brim. It is believed that these little reservoirs are useful to the plant during the flowering period, because they keep the ants away from the honey. Considering the internal structure of the stem at the base of these cups we find that the vascular bundles of the two opposite leaves are strongly connected [646] with one another, constituting a ring which narrowly surrounds the stem, and which would impede an increase in thickness, if such were in the nature of the plant. But since the stems end their existence during the summer of their development, this structure is of no real harm. The grouping of the leaves in alternate pairs may be seen within the bud as well as on the adult stems. In order to do this, it is necessary to make transverse sections through the heart of the rosette of the leaves of the first year. If cut through the base, the pair exhibit connate wings, corresponding to the water-cups; if cut above these, the leaves seem to be free from one another. In order to compare the position of leaves of the twisted plants with this normal arrangement, the best way is to make a corresponding section through the heart of the rosette of the first year. It is not necessary to make a microscopic preparation. In the fall the changed disposition may at once be seen to affect the central leaves of the group. All the rosettes of the whole race commence with opposite leaves; those that are to produce straight stems remain in this condition, but the preparation for twisting begins at the end of the first year as shown by a special arrangement of the leaves. This [647] disposition may then be seen to extend to the very center of the rosette, by use of microscopical sections. Examining sections made in the spring, the original arrangement of the leaves of the stem is observed to continue until the beginning of the growth of the shoot. It is easy to estimate the number of leaves corresponding to a given number of spiral circuits in these sections and the proportion is found to indicate 13 leaves on 5 turns. These figures are the same as those given above for the ordinary arrangement of alternate leaves in the main lines of the pedigree of the vegetable kingdom. Leaving aside for the moment the subsequent changes of this spiral arrangement, it becomes at once clear that here we have a case of systematic atavism. The twisted teasels lose their decussation, but in doing so the leaves are not left in a disorderly dispersion, but a distinct new arrangement takes its place, which is to be assumed as the normal one for the ancestors of the teasel family. The case is to be considered as one of atavism. Obviously no other explanation is possible, than the supposition that the 5-13 spiral is still latent, though not displayed by the teasels. But in the very moment when the faculty of decussation disappears, it resumes its place, and becomes [648] as prominent as it must once have been in the ancestors, and is still in that part of their offspring, which has not become changed in this respect. Thus the proof of our assertion of systematic atavism is, in this case, not obtained by the inspection of the adult, but by the investigation of the conditions in an early stage. It remains to be explained how the twisting may finally be caused by this incipient grouping of the leaves. Before doing so, it may be as well to state that the case of the teasel is not an isolated one, and that the same conclusions are supported by the valerian, and a large number of other examples. In early spring some rosettes show a special condition of the leaves, indicating thereby at once their atavism and their tendency to become twisted as soon as they begin to expand. The Sweet William or _Dianthus barbatus_ affords another instance; it is very interesting because a twisted race is available, which may produce thousands of instances developed in all imaginable degrees, in a single lot of plants. _Viscaria oculata_ is another instance belonging to the same family. The bedstraw (_Galium_) also includes many species which from time to time produce twisted stems. I have found them myself in Holland on _Galium verum_ and _G. Aparine_. Both seem [649] to be of rare occurrence, as I have not succeeded in getting any repetition by prolonged culture. Species, which generally bear their leaves in whorls, are also subjected to casual atavisms of this kind, as for instance the tall European horsetail, _Equisetum Telmateja_, which occasionally bears cones on its green summer stems. Its whorls are changed on the twisted parts into clearly visible spirals. The ironwood or _Casuarina quadrivalvis_ is sometimes observed to produce the same anomaly on its smaller lateral branches. Coming now to the discussion of the way in which the twisting is the result of the spiral disposition of the leaves, we may consider this arrangement on stems in the adult state. These at once show the spiral line and it is easy to follow this line from the base up to the apex. In the most marked cases it continues without interruption, not rarely however, ending in a whorl of three leaves and a subsequent straight internode, of which there may even be two or three. The spiral exhibits the basal parts of the leaves, with the axillary lateral branches. The direction of the screw is opposed to that of the twisting, and the spiral ribs are seen to cross the line of insertion of the leaves at nearly right angles. On this line the leaves are nearer [650] to one another than would correspond to the original proportion of 5 turns for 13 leaves. In fact, 10 or even 13 leaves may not rarely be counted on a single turn. Or the twist may become so strong locally as to change the spiral into a longitudinal line. On this line all inserted leaves extend themselves in the same direction, resembling an extended flag. The spiral on the stem is simply the continuation of the spiral line from within the rosettes of the first year. Accordingly it is seen to become gradually less steep at the base. For this reason it must be one and the same with this line, and in extreme youth it must have produced its leaves at the same mutual distances as this line. Transverse sections of the growing summits of the stems support this conclusion. From these several facts we may infer that the steepness of the spiral line increases on the stem, as it is gradually changed into a screw. Originally 5 turns were needed for 13 leaves, but this number diminishes and 4 or 3 or even 2 turns may take the same number of foliar organs, until the screw itself is changed into a straight line. This change consists in an unwinding of the whole spiral, and in order to effect this the stem must become wound up in the opposite direction. The winding of the foliar screw must [651] curve the longitudinal ribs. The straighter and steeper the screw becomes, the more the ribs will become twisted. That this happens in the opposite direction is obvious, without further discussion. The twisting is the inevitable consequence of the reversal of the screw. Two points remain to be dealt with. One is the direct proof of the reversal of the screw, the other the discussion of its cause. The first may be observed by a simple experiment. Of course it proceeds only slowly, but all that is necessary is to mark the position of one of the younger leaves of a growing stem of a twisting individual and to observe the change in its position in a few hours. It will be seen to have turned some way around the stem, and finally may be seen to make a complete revolution in the direction opposite to the screw, and thereby demonstrating the fact of its uncurling. The cause of this phenomenon is to be sought in the intimate connection of the basal parts of the leaves, which we have detailed above. The fibrovascular strands constitute a strong rope, which is twisted around the stem along the line on which the leaves are inserted. The strengthening of the internodes may stretch this rope to some extent, but it is too strong to be rent asunder. Hence it opposes the normal growth, and the only manner in which the internodes [652] may adjust themselves to the forces which tend to cause their expansion is by straightening the rope. In doing so they may find the required space, by growing out in an unusual direction, bending their axes and twisting the ribs. To prove the validity of this explanation, a simple experiment may be given. If the fibrovascular rope is the mechanical impediment which hinders the normal growth, we may try the effect of cutting through this rope. By this means the hindrance may at least locally be removed. Now, of course, the operation must be made in an early stage before, or at the beginning of the period of growth, in every case before the uncurling of the rope begins. Wounds made at this time are apt to give rise to malformations, but notwithstanding this difficulty I have succeeded in giving the necessary proof. Stems operated upon become straight where the rope is cut through, though above and under the wounded part they go on twisting in the usual way. Sometimes the plants themselves succeed in tearing the rope asunder, and long straight internodes divide the twisted stems in two or more parts in a very striking manner. A line of torn leaf-bases connects the two parts of the screw and gives testimony of what has passed within [653] the tissues. At other times the straightening may have taken place directly internal to a leaf, and it is torn and may be seen to be attached to the stem by two distinct bases. Summing up this description of the hereditary qualities of our twisted teasels and of their mechanical consequences, we may say that the loss of the normal decussation is the cause of all the observed changes. This special adaptation, which places the leaves in alternating pairs, replaced and concealed the old and universal arrangement on a screw line. In disappearing, it leaves the latter free, and according to the rule of systematic atavism, this now becomes active and takes its place. If the fibrovascular connection of the leaf-bases were lost at the same time the stems would grow and become straight and tall. This change however, does not occur, and the bases of the leaves now constitute a continuous rope instead of separate rings, and thereby impede the stretching of the internodes. These in their turn avoid the difficulty by twisting themselves in a direction opposite to that of the spiral of the leaves. As a last example of systematic atavism I will refer to the reversionary changes, afforded by the tomatoes. Though the culture of this plant is a recent one, it seems to be at present in a state of mutability, producing new strains, or [654] assuming the features of their presumable ancestors. In his work "The Survival of the Unlike," Bailey has given a detailed description of these various types. Moreover, he has closely studied the causes of the changes, and shown the great tendency of the tomatoes to vicinism. By far the larger part of the observed cases of running out of varieties are caused by accidental crosses through the agency of insects. Even improvements are not rarely due to this cause. Besides these common and often unavoidable changes, others of greater importance occur from time to time. Two of them deserve to be mentioned. They are called the "Upright" and the "Mikado" types, and differ as much or even more from their parents than the latter do from any one of their wild congeners. Their characters come true from seed. The "Mikado" race or the _Lycopersicum grandifolium_ (_L. latifolium_) has larger and fewer leaflets than the slender and somewhat flimsy foliage of the common form. Flat or plane blades with decurrent margins constitute another character. This variety, however, does not concern our present discussion. The upright type has stiff and self-sustaining stems and branches, resembling rather a potato-plant than a tomato. Hence the name _Lycopersicum solanopsis_ or _L. validum_, under which it is usually described. [655] The foliage of the plant is so distinct as to yield botanical characters of sufficient importance to justify this specific designation. The leaflets are reduced in numbers and greatly modified, and the flowers in the inflorescence are reduced to two or three. This curious race came in suddenly, without any premonition, and the locality and date of its mutation are still on record. Until some years ago it had not made its appearance for a second time. Obviously it is to be considered as a reversionary form. The limp stems of the common tomatoes are in all respects indicative of the cultivated condition. They cannot hold themselves erect, but must be tied up to supports. The color of the leaves is a paler green than should be expected from a wild plant. Considering other species of the genus _Solanum_, of which the _Lycopersicum_ is a subdivision, the stems are as a rule erect and self-supporting, with some few exceptions. These, however, are special adaptations as shown by the winding stems of the bitter-sweet. From this discussion we seem justified in concluding that the original appearance of the upright type was of the nature of systematic atavism. It differs however, from the already detailed cases in that it is not a monstrosity, nor an ever-sporting race, but is as constant a form [656] as the best variety or species. Even on this ground it must be considered as a representative of a separate group of instances of the universal rule of systematic reversions. Of late the same mutation has occurred in the garden of C.A. White at Washington. The parent form in this case was the "Acme," of the ordinary weak and spreading habit of growth. It is known as one of the best and most stable of the varieties and was grown by Mr. White for many years, and had not given any sign of a tendency towards change. Seeds from some of the best plants in 1899 were sown the following spring, and the young seedlings unexpectedly exhibited a marked difference from their parents. From the very outset they were more strong and erect, more compact and of a darker green than the "Acme." When they reached the fruiting stage they had developed into typical representatives of the _Lycopersicum solanopsis_ or upright division. The whole lot of plants comprised only some 30 specimens, and this number, of course, is too small to base far-reaching conclusions upon. But all of the lot showed this type, no true "Acme" being seen among them. The fruit differed in flavor, consistency and color from that of the parent, and it also ripened earlier than the latter. No seed was saved from [657] these plants, but the following year the "Acme" was sown again and found true to its type. Seeds saved from this generation in 1900 have, however, repeated the mutation, giving rise to exactly the same new upright form in 1901. This was called by its originator "The Washington." Seeds from this second mutation were kindly sent to me by Mr. White, and proved true to their type when sown in my garden. Obviously it is to be assumed in the case of the tomatoes as well as in instances from other genera cited, that characters of ancestors, which are not displayed in their progeny, have not been entirely lost, but are still present, though in a latent condition. They may resume their activity unexpectedly, and at once develop all the features which they formerly had borne. Latency, from this point of view, must be one of the most common things in nature. All organisms are to be considered as internally formed of a host of units, partly active and partly inactive. Extremely minute and almost inconceivably numerous, these units must have their material representatives within the most intimate parts of the cells. [658] LECTURE XXIII TAXONOMIC ANOMALIES The theory of descent is founded mainly on comparative studies, which have the advantage of affording a broad base and the convincing effect of concurrent evidence brought together from widely different sources. The theory of mutation on the other hand rests directly upon experimental investigations, and facts concerning the actual descent of one form from another are as yet exceedingly rare. It is always difficult to estimate the validity of conclusions drawn from isolated instances selected from the whole range of contingent phenomena, and this is especially true of the present case. Systematic and physiologic facts seem to indicate the existence of universal laws, and it is not probable that the process of production of new species would be different in the various parts of the animal and vegetable kingdoms. Moreover the principle of unit-characters, the preeminent significance of which has come to be more fully recognized of late, is in full harmony [659] with the theory of sudden mutations. Together these two conceptions go to strengthen the probability of the sudden origin of all specific characters. Experimental researches are limited in their extent, and the number of cases of direct observation of the process of mutation will probably never become large enough to cover the whole field of the theory of descent. Therefore it will always be necessary to show that the similarity between observed and other cases is such as to lift above all doubt the assertion of their resulting from the same causes. Besides the direct comparison of the mutations described in our former lectures, with the analogous cases of the horticultural and natural production of species and varieties at large, another way is open to obtain the required proof. It is the study of the phenomena, designated by Casimir de Candolle by the name of taxonomic anomalies. It is the assertion that characters, which are specific in one case, may be observed to arise as anomalies or as varieties in other instances. If they can be shown to be identical or nearly so in both, it is obviously allowable to assume the same origin for the specific character and for the anomaly. In other terms, the specific marks may be considered as having originated according to the laws [660] that govern the production of anomalies, and we may assume them to lie within reach of our experiments. The experimental treatment of the origin of species may also be looked upon as a method within our grasp. The validity and the significance of these considerations will at once become clear, if we choose a definite example. The broadest and most convincing one appears to me to be afforded by the cohesion of the petals in gamopetalous flowers. According to the current views the families with the petals of their flowers united are regarded as one or two main branches of the whole pedigree of the vegetable kingdom. Eichler and others assume them to constitute one branch, and therefore one large subdivision of the system. Bessey, on the other hand, has shown the probability of a separate origin for those groups which have inferior ovaries. Apart from such divergencies the connation of the petals is universally recognized as one of the most important systematic characters. How may this character have originated? The heath-family or the Ericaceae and their nearest allies are usually considered to be the lowest of the gamopetalous plants. In them the cohesion of the petals is still subject to reversionary exceptions. Such cases of atavism may [661] be observed either as specific marks, or in the way of anomalies. _Ledum_, _Monotropa_ and _Pyrola_, or the Labrador tea, the Indian pipe and wintergreen are instances of reversionary gamopetalism with free petals. In heaths (_Erica Tetralix_) and in rhododendrons the same deviation is observed to occur from time to time as an anomaly, and even the common _Rhododendron ponticum_ of our gardens has a variety in which the corolla is more or less split. Sometimes it exhibits five free petals, while at other times only one or two are entirely free, the remaining four being incompletely loosened. Such cases of atavism make it probable that the coherence of the petals has originally arisen by the same method, but by action in the opposite direction. The direct proof of this conclusion is afforded by a curious observation, made by Vilmorin upon the bright and large-flowered garden-poppy, _Papaver bracteatum_. Like all poppies it has four petals, which are free from one another. In the fields of Messrs. Vilmorin, where it is largely cultivated for its seeds, individuals occur from time to time which are anomalous in this respect. They exhibit a tendency to produce connate petals. Their flowers become monopetalous, and the whole strain is designated by the name of _Papaver_ [662] _bracteatum monopetalum_. Henry de Vilmorin had the kindness to send me some of these plants, and they have flowered in my garden during several years. The anomaly is highly variable. Some flowers are quite normal, exhibiting no sign of connation; others are wholly gamopetalous, the four petals being united from their base to the very margin of the cup formed. In consequence of the broadness of the petals however, this cup is so wide as to be very shallow. Intermediate states occur, and not infrequently. Sometimes only two or three petals are united, or the connation does not extend the entire length of the petals. These cases are quite analogous to the imperfect splitting of the corolla of the rhododendron. Giving free rein to our imagination, we may for a moment assume the possibility of a new subdivision of the vegetable kingdom, arising from Vilmorin's poppy and having gamopetalous flowers for its chief character. If the character became fixed, so as to lose its present state of variability, such a group of supposititious gamopetalous plants might be quite analogous to the corresponding real gamopetalous families. Hence there can be no objection to the view, that the heaths have arisen in an analogous manner from their polypetalous ancestors. Other species of [663] the same genus have also been recorded to produce gamopetalous flowers, as for instance, _Papaver hybridum_, by Hoffmann. Poppies are not the sole example of accidental gamopetaly. Linnaeus observed the same deviation long ago for _Saponaria officinalis_, and since, it has been seen in _Clematis Vitalba_ by Jaeger, in _Peltaria alliacea_ by Schimper, in _Silene annulata_ by Boreau and in other instances. No doubt it is not at all of rare occurrence, and the origin of the present gamopetalous families is to be considered as nothing extraordinary. It is, as a matter of fact, remarkable that it has not taken place in more numerous instances, and the mallows show that such opportunities have been available at least more than once. Other instances of taxonomic anomalies are afforded by leaves. Many genera, the species of which mainly bear pinnate or palmate leaves, have stray types with undivided leaves. Among the brambles, _Rubus odoratus_ and _R. flexuosus_ may be cited, among the aralias, _Aralia crassifolia_ and _A. papyrifera_, and among the jasmines, the deliciously scented sambac (_Jasminum Sambac_). But the most curious instance is that of the telegraph-plant, or _Desmodium gyrans_, each complete leaf of which consists of a large terminal leaflet and two little lateral ones. These latter keep up, [664] night and day, an irregular jerking movement, which has been compared to the movements of a semaphore. _Desmodium_ is a papilionaceous plant and closely allied to the genus _Hedysarum_, which has pinnate leaves with numerous pairs of leaflets. Its place in the system leaves no doubt concerning its origin from pinnate-leaved ancestors. At the time of its origination its leaves must have become reduced as to the number of the blades, while the size of the terminal leaflet was correspondingly increased. It might seem difficult to imagine this great change taking place suddenly. However, we are compelled to familiarize ourselves with such hypothetical assumptions. Strange as they may seem to those who are accustomed to the conception of continuous slow improvements, they are nevertheless in complete agreement with what really occurs. Fortunately the direct proof of this assertion can be given, and in a case which is narrowly related, and quite parallel to that of the _Desmodium_, since it affects a plant of the same family. It is the case of the monophyllous variety of the bastard-acacia or _Robinia Pseud-Acacia_. In a previous lecture we have seen that it originated suddenly in a French nursery in the year 1855. It can be propagated by seed, and exhibits a curious degree [665] of variability of its leaves. In some instances these are one-bladed, the blade reaching a length of 15 cm., and hardly resembling those of the common bastard-acacia. Other leaves produce one or two small leaflets at the base of the large terminal one, and by this contrivance are seen to be very similar to those of the _Desmodium_, repeating its chief characters nearly exactly, and only differing somewhat in the relative size of the various parts. Lastly real intermediates are seen between the monophyllous and the pinnate types. As far as I have been able to ascertain, these are produced on weak twigs under unfavorable conditions; the size of the terminal leaflet decreases and the number of the lateral blades increases, showing thereby the presence of the original pinnate type in a latent condition. The sudden origin of this "one-leaved" acacia in a nursery may be taken as a prototype of the ancient origin of _Desmodium_. Of course the comparison only relates to a single character, and the movements of the leaflets are not affected by it. But the monophylly, or rather the size of the terminal blade and the reduction of the lateral ones, may be held to be sufficiently illustrated by the bastard-acacia. It is worth while to state, that analogous varieties have also arisen in other genera. The "one-leaved" [666] strawberry has already been referred to. It originated from the ordinary type in Norway and at Paris. The walnut likewise, has its monophyllous variety. It was mentioned for the first time as a cultivated tree about 1864, but its origin is unknown. A similar variety of the walnut, with "one-bladed" leaves but of varying shapes, was found wild in a forest near Dieppe in France some years ago, and appeared to be due to a sudden mutation. Something more is known concerning the "one-bladed" ashes, varieties of which are often seen in our parks and gardens. The common form has broad and deeply serrate leaves, which are far more rounded than the leaflets of the ordinary ash. The majority of the leaves are simple, but some produce one or two smaller leaflets at their base, closely corresponding in this respect to the variations of the "one-bladed" bastard-acacia, and evidently indicating the same latent and atavistic character. In some instances this analogy goes still further, and incompletely pinnate leaves are produced with two or more pairs of leaflets. Besides this variable type another has been described by Willdenow. It has single leaves exclusively, never producing smaller lateral leaflets, and it is said to be absolutely constant from seed, while the more variable types [667] seem to be also more inconstant when propagated sexually. The difference is so striking and affords such a reliable feature that Koch proposed to make two distinct varieties of them, calling the pure type _Fraxinus excelsior monophylla_, and the varying trees _F. excelsior exheterophylla_. Some writers, and among them Willdenow, have preferred to separate the "one-leaved" forms from the species, and to call them _Fraxinus simplicifolia_. According to Smith and to Loudon, the "one-leaved" ashes are found wild in different districts in-England. Intermediate forms have not been recorded from these localities. This mode of origin is that already detailed for the laciniate varieties of alders and so many other trees. Hence it may be assumed that the "one-leaved" ashes have sprung suddenly but frequently from the original pinnate species. The pure type of Willdenow should, in this case, be considered as due to a slightly different mutation, perhaps as a pure retrograde variety, while the varying strains may only be eversporting forms. This would likewise explain part of their observed inconstancy. In this respect the historic dates, as collected by Korshinsky, are not very convincing. Vicinism has of course, almost never been excluded, and part of the multiformity of the offspring [668] must obviously be due to this most universal agency. Indirect vicinism also plays some part, and probably affords the explanation of some reputed mutative productions of the variety. So, for instance, in the case of Sinning, who after sowing the seeds of the common ash, got as large a proportion as 2% of monophyllous trees in a culture of some thousand plants. It is probable that his seeds were taken partly from normal plants, and partly from hybrids between the normal and the "one-bladed" type, assuming that these hybrids have pinnate leaves like their specific parent, and bear the characters of the other parent only in a latent condition. Our third example relates to peltate leaves. They have the stalk inserted in the middle of the blade, a contrivance produced by the connation of the two basal lobes. The water-lilies are a well known instance, exhibiting sagittate leaves in the juvenile stage and changing in many species, into nearly circular peltate forms, of which _Victoria regia_ is a very good example, although its younger stages do not always excite all the interest they deserve. The Indian cress (_Tropaeolum_), the marsh pennywort or _Hydrocotyle_, and many other instances could be quoted. Sometimes the peltate leaves are not at all orbicular, but are elongated, oblong or elliptic, and with only the lobes [669] at the base united. The lemon-scented _Eucalyptus citriodora_ is one of the most widely known cases. In other instances the peltate leaves become more or less hollow, constituting broad ascidia as in the case of the crassulaceous genus _Umbilicus_. This connation of the basal lobes is universally considered as a good and normal specific character. Nevertheless it has its manifest analogy in the realm of the anomalies. This is the pitcher or ascidium. On some trees it is of quite common occurrence, as on the lime-tree (_Tilia parvifolia_) and the magnolia (_Magnolia obovata_ and its hybrids). It is probable that both these forms have varieties with, and others without, ascidia. Of the lime-tree, instances are known of single trees which produce hundreds of such anomalous leaves yearly, and one such a tree is growing in the neighborhood of Amsterdam at Lage Vuursche. I have alluded to these cases more than once, but on this occasion a closer inspection of the structure of the ascidium is required. For this purpose we may take the lime-tree as an example. Take the shape of the normal leaves in the first place. These are cordate at their base and mainly inequilateral, but the general shape varies to a considerable extent. This variation is closely related to the position of the leaves on the twigs, and shows [670] distinct indications of complying with the general law of periodicity. The first leaves are smaller, with more rounded lobes, the subsequent leaves attain a larger size, and their lobes slightly change their forms. In the first leaves the lobes are so broad as to touch one another along a large part of their margins, but in organs formed later this contact gradually diminishes and the typical leaves have the lobes widely separated. Now it is easily understood that the contact or the separation of the lobes must play a part in the construction of the ascidia, as soon as the margins grow together. Leaves which touch one-another, may be affected by the connation without any further malformation. They remain flat, become peltate and exhibit a shape which in some way holds a middle position between the pennyworts and the lemon-scented eucalyptus. Here we have the repetition of the specific characters of these plants by the anomaly of another. Whenever the margins are not in contact, and become connate, notwithstanding their separation, the blade must be folded together in some slight degree, in order to produce the required contact. This is the origin of the ascidium. It is quite superfluous to insist upon the fact that their width or narrowness must depend upon the corresponding normal form. The more distant the [671] lobes, the deeper the ascidium will become. It should be added that this explanation of the different shapes of ascidia is of general validity. Ascidia of the snake-plantain or _Plantago lanceolata_ are narrow tubes, because the leaves are oblong or lanceolate, while those of the broad leaved species of arrowhead, as for instance, the _Sagittaria japonica_, are of a conical shape. From the evidence of the lime-tree we may conclude that normal peltate leaves may have originated in the same way. And from the fact that pitchers are one of the most frequent anomalies, we may conclude that the chance of producing peltate leaves must have been a very great one, and wholly sufficient to account for all observed cases. In every instance the previously existing shape of the leaf must have decided whether peltate or pitcher-like leaves would be formed. As far as we can judge peltate anomalies are quite uninjurious, while ascidia are forms which must impede the effect of the light on the leaf, as they conceal quite an important part of the upper surface. In this way it is easily conceivable that peltate leaves are a frequent specific character, while ascidia are not, as they only appear in the special cases of limited adaptation, as in the instances of the so called pitcher-plants. The genera _Nepenthes_, [672] _Sarracenia_ and some others are very well known and perhaps even the bladderworts or _Utricularia_ might be included here. The reproduction of specific characters by anomalous ascidia is not at all limited to the general case as described above. More minute details may be seen to be duplicated in the same way. Proofs are afforded on one side by incomplete ascidia, and on the other by the double cups. Incomplete ascidia are those of the _Nepenthes_. The leaf is divided into three parts, a blade, a tendril and the pitcher. Or in other words, the limb produces a tendril at its summit, by means of which the plant is enabled to fasten itself to surrounding shrubs and to climb between their branches. But the end of this tendril bears a well-formed urn, which however, is produced only after the revolving and grasping movements of the tendril have been made. Some species have more rounded and some more elongated ascidia and often the shape is seen to change with the development of the stem. The mouth of the urn is strengthened by a thick rim and covered with a lid. Numerous curious contrivances in these structures to catch ants and other insects have been described, but as they have no relation to our present discussion, we shall abstain from dealing with them. [673] Likewise we must refrain from a consideration of the physiologic qualities of the tendril, and confine our attention to the combination of a limb, a naked midvein and an ascidium. This combination is to be the basis of our discussion. It is liable to be produced all of a sudden. This assertion is proved by its occurrence as a varietal mark in one of our most ordinary cultivated plants. It is the group known as _Croton_, belonging to the genus _Codiaeum_. A variety is called _interruptum_ and another _appendiculatum_, and these names both relate to the interruption of the leaves by a naked midvein. The leaves are seen to be built up of three parts. The lower half retains the aspect of a limb; it is crowned by a vein without lateral nerves or blade-like expansions, and this stalk in its turn bears a short limb on its summit. The base of this apical limb exhibits two connate lobes, forming together a wide cup or ascidium. It should be stated that these _interruptum_ varieties are highly variable, especially in the relative size of the three principal parts of the leaf. Though it is of course conceded that the ascidium of _Nepenthes_ has many secondary devices which are lacking in _Croton_, it seems hardly allowable to deny the possibility of an analogous origin for both. Those of the _Croton_, according to our knowledge regarding similar cases, must [674] have arisen at once, and hence the conclusion that the ascidia of _Nepenthes_ are also originally due to a sudden mutation. Interrupted leaves, with an ascidium on a naked prolongation of the midvein, are by no means limited to the _Croton_ varieties. As stray anomalies they have often been observed, and I myself had the opportunity of collecting them on magnolia, on clover and on some other species. They are additional evidence in support of the explanation given above. In the same way double ascidia may be made use of to explain the foliar cups of the teasels and some other plants, as for instance, some European snakeroots (_Eryngium maritimum_ and _E. campestre_), or the floral leaves of the honeysuckle. The leaves on the stems of the teasels are disposed in pairs, and the bases of the two leaves of each pair are connate so as to constitute large cups. We have already mentioned these cups, and recall them in the present connection to use them as a prototype of the double ascidia. These are constituted of two opposite leaves, accidentally connated at their base or along some part of their margins. If the leaves are sessile, the analogy with the teasels is complete, as shown, for instance, in a case of _Cotyledon_, a crassulaceous plant which is [675] known to produce such cups from time to time. They are narrower than those of the teasel, but this depends, as we have seen for the "one-leaved" ascidium, on the shape of the original leaf. In other respects they exactly imitate the teasel cups showing thereby how these cups may probably have originated. In numerous cases of anomalies some accidental structures are parallel to specific characters, while others are not, being obviously injurious to their bearers. So it is also with the double ascidia. In the case of stalked leaves the two opposite stalks must, of course, constitute a long and very narrow tube, when growing together. This tube must bear at its summit the conical ascidium produced by the two connate limbs. At its base however, it includes the terminal bud of the stem, and frequently the tube is so narrow as to impede its further development. By this contrivance the double ascidium assumes a terminal position. Instances have been observed on magnolia, in _Boehmeria_ and in other cases. Flowers on leaves are of rare occurrence. Notwithstanding this, they constitute specific characters in some instances, accidental anomalies in others. _Helwingia rusciflora flora_ is the most curious and best known instance. It is a little shrub, belonging to the Cornaceae, and [676] has broad elliptical undivided leaves. On the middle of the midvein these leaves are seen to bear small clusters of flowers; indeed this is the only place where flowers are produced. Each cluster has from 13-15 flowers, of which some are staminate and borne on stalks, while others are pistillate and nearly sessile. These flowers are small and of a pale greenish color and yield small stone-fruits, with a thin coating of pulpy tissue. As the name indicates, this mode of flowering is closely similar to that of _Ruscus_, which however, does not bear its flowers and berries on real leaves, but on leaflike expansions of the twigs. _Phyllonoma ruscifolia_, a saxifragaceous plant, bears the same specific name, indicating a similar origin of the flowers. Other instances have been collected by Casimir de Candolle, but their number is very small. As a varietal mark, flowers on leaves likewise rarely occur. One instance however, is very remarkable, and we have already dealt with it, when treating of constant varieties, and of the lack of vicinism in the case of species with exclusive self-fertilization. It is the "Nepaul-barley" or _Hordeum trifurcatum_. The leaves, which in this case bear the adventitious flowers, are the inner scales of the spikelets, and not on green leaves as in the [677] cases already alluded to. But this of course makes no real difference. The character is variable to a high degree, and this fact indicates its varietal nature, though it should be recalled that at least with the _Helwingia_, the majority of the leaves are destitute of flowers, and that in this way some degree of variability is present in this normal case too. All in all there are three sorts of "Nepaul-barley." They have the same varietal mark, but belong to different species of barley. These are differentiated according to the number of the rows in which the grains are seen on the spikes. These numbers may be two, four or six, giving rise to the specific names of _Hordeum distichum_, _tetrastichum_ and _hexastichum_. Whether these three varieties are of independent, but parallel origin, or are to be considered as due to a single mutation and subsequent crosses is not known, all of them being of ancient origin. Historic evidence concerning their birth is wholly wanting. From analogy it would seem probable that the character had arisen by a mutation in one of the three named species, and had been transferred to others by means of accidental crosses, even as it has been artificially transmitted of late to quite a number of other sorts. But however admissible this conception may seem, there is of course no real objection [678] to the assumption of independent and parallel mutations. For the purpose of a comparison with the _Helwingia_ type we are however, not at all concerned with the species to which the _trifurcatum_ variety belongs, but only with the varietal mark itself. The spikelets may be one-, two- or three-flowered, according to the species. If we choose for further consideration the _hexastichum_ type, each spikelet produces three normal flowers and afterwards three normal grains. Morphologically however, the spikelet is not homologous to those parts of other grasses which have the same name. It is constituted of three real spikelets, and thus deserves the name of a triple construction. Each of these three little organs has its normal pair of outer scales or glumae. These are linear and short, ending in a long and narrow spine. Those of the middle-most spikelets stand on its outer side, while those of the lateral part are placed transversely. In this way they form a kind of involucre around the central parts. The latter consist of the inner and outer palets or scales, each two of which include one of the flowers. The outer palet is to be considered as the metamorphosed leaf, in the aril of which the flower is produced. In the common sorts of barley it bears a long awn, giving thereby its typical aspect to the [679] whole spike. The axillary flower is protected on the opposite side by a two-keeled inner palet. Each flower exhibits three stamens and an ovary. In the six-rowed barley all the three flowers of a triple spikelet are fertile, and each of them has a long awn on the top of the outer palet. But in the two-rowed species only the middle-most flower is normal and has an awn, the two remaining being sterile and more or less rudimentary and with only very short awns. From this description it is easily seen that the species of barley may be distinguished from one another, even at a casual glance, by the number of the rows of the awns, and therefore by the shape of the entire spikes. This striking feature, however, does not exist in the "Nepaul-barley." The awns are replaced by curiously shaped appendices, which are three-lobed. The central lobe is oblong and hollow, and forms a kind of hood, which covers a small supernumerary floret. The two lateral lobes are narrower, often linear and extended into a smaller or longer awn. These awns are mostly turned away from the center of the spike. The central lobe may sometimes bear two small florets, but ordinarily only one is to be found, and this is often incomplete, having only one or two stamens, or is different in some other way. [680] These narrow lateral lobes heighten the abnormal aspect of the whole spike. They are only produced at a somewhat advanced stage of the development of the palet, are united to one another and to the central part by strong veins, which form transversal anastomoses at their insertion. The length of these awns is very variable, and this quality is perhaps the most striking of the whole variety. Often they reach only 1-2 mm., or the majority may become longer and attain even 1 cm., while here and there, between them, longer ones are inserted, extending in some instances even as far as 3 cm. from the spike. Their transverse position in such cases is strikingly contrasted with the ordinary erect type of the awns. These lateral lobes are to be regarded, from the morphologic point of view, as differentiated parts of the blade of the leaf. Before they are formed, or coincidently with the beginning of their development, the summit of the central lobe becomes hollow, and the development of the supernumerary flower commences. In different varieties, and especially in the most recent crosses of them, this development is excessively variable. The accidental flower arises at some distance beneath the summit of the scale, on its middle [681] vein. The development begins with the protrusion of a little scale, and the flower itself is situated beneath this scale, and is to be protected by it and by the primary scale, but is turned upside down at the same time. Opposite to this organ, which represents the outer palet of the adventitious flower, two little swollen bodies are evolved. In the normal flowers of barley and other grains and grasses their function is to open the flowers by swelling, and afterwards collapse and allow them to close. In the adventitious flowers of the "Nepaul-barley," however, this function is quite superfluous. The stamens occur in varying numbers; typically there are three, but not rarely less, or more, are seen. In some instances the complete double whorl of six, corresponding to the ancestral monocotyledonous type, has been found. This is a very curious case of systematic atavism, quite analogous to the _Iris pallida abavia_, previously alluded to, which likewise has six stamens, and to the cases given in a previous lecture. But for our present discussion it is of no further interest. The ovary is situated in the middle of the flower, and in some instances two have been observed. This is also to be considered as a case of atavism. All these parts of the adventitious flower are more or less subject to arrest of development, [682] in a later stage. They may even sometimes become abnormal. Stamens may unite into pairs, or carpels bear four stigmas. The pollen-sacs are as a rule barren, the mother-cells undergoing atrophy, while normal grains are seen but rarely. Likewise the ovaries are rudimentary, but Wittmack has observed the occasional production of ripe grains from these abnormal florets. The scale is seldom seen to extend any farther upwards than the supernumerary flower. But in the rare instances where it does prolong its growth, it may repeat the abnormality and bear a second floret above the first. This of course is generally much weaker, and more rudimentary. Raciborsky, who has lately given a full and very accurate description of this anomaly, lays great stress upon the fact that it is quite useless. It is perhaps the most obviously useless structure in the whole vegetable kingdom. Notwithstanding this, it has come to be as completely hereditary as any of the most beautiful adaptations in nature. Therefore it is one of the most serious objections to the hypothesis of slow and gradual improvements on the sole ground of their usefulness. The struggle for life and natural selection are manifestly inadequate to give even the slightest indication of [683] an explanation of this case. It is simply impossible to imagine the causes that might have produced such a character. The only way out of this difficulty is to assume that it has arisen at once, in its present apparently differentiated and very variable condition, and that, being quite uninjurious and since it does not decrease the fertility of the race, it has never been subjected to natural selection, and so has saved itself from destruction. But if we once grant the probability of the origin of the "Nepaul-barley" by a sudden mutation, we obviously must assume the same in the case of the _Helwingia_ and other normal instances. In this way we gain a further support for our assertion, that even the strangest specific characters may have arisen suddenly. After having detailed at some length those proofs which seem to be the most striking, and which had not been previously described with sufficient detail, we may now take a hasty survey of other contingent cases. In the first place the cruciate flowers of some onagraceous plants should be remembered. Small linear petals occur as a specific character in _Oenothera cruciata_ of the Adirondacks, but have been seen to arise as sudden mutations in the common evening-primrose (_O. biennis_) in Holland, and in the willow-herb (_Epilobium hirsutum_) in England. [684] Leaves placed in whorls of three are very rare. The oleander, juniper and some few other plants have ternate whorls as a specific character. As an anomaly, ternate whorls are far more common, and perhaps any plant with opposite leaves may from time to time produce them. Races rich in this abnormality are found in the wild state in the yellow loosestrife or _Lysimachia vulgaris_, in which it is a very variable specific character, the whorls varying from two to four leaves. In the cultivated state it is met with in the myrtle or _Myrtus communis_, where it has come to be of some importance in Israelitic ritual. Crisped leaves are known in a mallow, _Malva crispa_, and as a variety in cabbages, parsley, lettuce and others. The orbicular fruits of Heeger's shepherd's purse (_Capsella heegeri_) recall similar fruits of other cruciferous genera, as for instance, _Camelina_. Screw-like stems with wide spirals are specific in the flower-stalks of _Cyclamen_ and _Vallisneria_, varietal in _Juncus effusus spiralis_ and accidental in _Scirpus lacustris_. Dormant buds or small bulbs in inflorescences are normal for wild onions, _Polygonum viviparum_ and others, varietal in _Poa alpina vivipara_ and perhaps in _Agave vivipara_, and accidental in plantains (_Plantago lanceolata_), _Saxifraga umbrosa_ and others. [685] Cleft leaves, one of the most general anomalies, are typical in _Boehmeria biloba_. The adnation of the peduncles of the inflorescences to the stem is typical in _Solanum_ and accidental in many other cases. It seems quite superfluous to add further proof. It is a very general phenomenon that specific characters occur in other genera as anomalies, and under such circumstances that the idea of a slow evolution on the ground of utility is absolutely excluded. No other explanation remains than that of a sudden mutation, and once granted for the abnormal cases, this explanation must obviously likewise be granted for the analogous specific characters. Our whole discussion shows that mutations, once observed in definite instances, afford the most probable basis for the explanation of specific characters at large. [686] LECTURE XXIV THE HYPOTHESIS OF PERIODIC MUTATIONS The prevailing belief that slow and gradual, nearly invisible changes constitute the process of evolution in the animal and vegetable kingdom, did not offer a strong stimulus for experimental research. No appreciable response to any external agency was of course to be expected. Responses were supposed to be produced, but the corresponding outward changes would be too small to betray themselves to the investigator. The direct observation of the mutations of the evening-primrose has changed the whole aspect of the problem at once. It is no longer a matter dealing with purely hypothetical conditions. Instead of the vague notions, uncertain hopes, and a priori conceptions, that have hitherto confused the investigator, methods of observation have been formulated, suitable for the attainment of definite results, the general nature of which is already known. To my mind the real value of the discovery [687] of the mutability of the evening-primrose lies in its usefulness as a guide for further work. The view that it might be an isolated case, lying outside of the usual procedure of nature, can hardly be sustained. On such a supposition it would be far too rare to be disclosed by the investigation of a small number of plants from a limited area. Its appearance within the limited field of inquiry of a single man would have been almost a miracle. The assumption seems justified that analogous cases will be met with, perhaps even in larger numbers, when similar methods of observation are used in the investigation of plants of other regions. The mutable condition may not be predicated of the evening-primroses alone. It must be a universal phenomenon, although affecting a small proportion of the inhabitants of any region at one time: perhaps not more than one in a hundred species, or perhaps not more than one in a thousand, or even fewer may be expected to exhibit it. The exact proportion is immaterial, because the number of mutable instances among the many thousands of species in existence must be far too large for all of them to be submitted to close scrutiny. It is evident from the above discussion that next in importance to the discovery of the prototype of mutation is the formulation of methods [688] for bringing additional instances to light. These methods may direct effort toward two different modes of investigation. We may search for mutable plants in nature, or we may hope to induce species to become mutable by artificial methods. The first promises to yield results most quickly, but the scope of the second is much greater and it may yield results of far more importance. Indeed, if it should once become possible to bring plants to mutate at our will and perhaps even in arbitrarily chosen directions, there is no limit to the power we may finally hope to gain over nature. What is to guide us in this new line of work? Is it the minute inspection of the features of the process in the case of the evening-primroses? Or are we to base our hopes and our methods on broader conceptions of nature's laws? Is it the systematic study of species and varieties, and the biologic inquiry into their real hereditary units? Or is the theory of descent to be our starting-point? Are we to rest our conceptions on the experience of the breeder, or is perhaps the geologic pedigree of all organic life to open to us better prospects of success? The answer to all such questions is a very simple one. All possibilities must be considered, and no line of investigation ignored. For myself I have based my field-researches and my [689] testing of native plants on the hypothesis of unit-characters as deduced from Darwin's _Pangenesis_. This conception led to the expectation of two different kinds of variability, one slow and one sudden. The sudden ones known at the time were considered as sports, and seemed limited to retrograde changes, or to cases of minor importance. The idea that sudden steps might be taken as the principal method of evolution could be derived from the hypothesis of unit characters, but the evidence might be too remote for a starting point for experimental investigation. The success of my test has given proof to the contrary. Hence the assertion that no evidence is to be considered as inadequate for the purpose under discussion. Sometime a method of discovering, or of producing, mutable plants may be found, but until this is done, all facts of whatever nature or direction must be made use of. A very slight indication may change forever the whole aspect of the problem. The probabilities are now greatly in favor of our finding out the causes of evolution by a close scrutiny of what really happens in nature. A persistent study of the physiologic factors of this evolution is the chief condition of success. To this study field-observations may contribute as well as direct experiments, [690] microscopical investigations as well as extended pedigree-cultures. The cooperation of many workers is required to cover the field. Somewhere no doubt the desired principle lies hidden, but until it is discovered, all methods must be tried. With this conception as the best starting point for further investigation, we may now make a brief survey of the other phase of the problem. We shall try to connect our observations on the evening-primroses with the theory of descent at large. We start with two main facts. One is the mutability of Lamarck's primrose, and the second is the immutable condition of quite a number of other species. Among them are some of its near allies, the common and the small flowered evening-primrose, or _Oenothera biennis_ and _O. muricata_. From these facts, a very important question arises in connection with the theory of descent. Is the mutability of our evening-primroses temporary, or is it a permanent condition? A discussion of this problem will give us the means of reaching a definite idea as to the scope of our inquiries. Let us consider the present first. If mutability is a permanent condition, it has of course no beginning, and moreover is not due to the [691] agency of external circumstances. Should this be granted for the evening-primrose, it would have to be predicated for other species found in a mutable state. Then, of course, it would be useless to investigate the causes of mutability at large, and we should have to limit ourselves to the testing of large numbers of plants in order to ascertain which are mutable and which not. If, on the other hand, mutability is not a permanent feature, it must once have had a beginning, and this beginning itself must have had an external cause. The amount of mutability and its possible directions may be assumed to be due to internal causes. The determination of the moment at which they will become active can never be the result of internal causes. It must be assigned to some external factor, and as soon as this is discovered the way for experimental investigation is open. In the second place we must consider the past. On the supposition of permanency all the ancestors of the evening-primrose must have been mutable. By the alternative view mutability must have been a periodic phenomenon, producing at times new qualities, and at other times leaving the plants unchanged during long successions of generations. The present mutable state must then have been preceded by an immutable [692] condition, but of course thousands of mutations must have been required to produce the evening-primroses from their most remote ancestors. If we take the species into consideration that are not mutable at present, we may ask how we are to harmonize them with each of the two theories proposed. If mutability is permanent, it is manifest that the whole pedigree of the animal and vegetable kingdom is to be considered as built up of main mutable lines, and that the thousands of constant species can only be taken to represent lateral branches of the genealogic tree. These lateral branches would have lost the capacity of mutating, possessed by all their ancestors. And as the principle of the hypothesis under discussion does not allow a resumption of this habit, they would be doomed to eternal constancy until they finally die out. Loss of mutability, under this conception, means loss of the capacity for all further development. Only those lines of the main pedigree which have retained this capacity would have a future; all others would die out without any chance of progression. If, on the other hand, mutability is not permanent, but a periodic condition, all lines of the genealogic tree must be assumed to show alternatively [693] mutating and constant species. Some lines may be mutating at the present moment; others may momentarily be constant. The mutating lines will probably sooner or later revert to the inactive state, while the powers of development now dormant may then become awakened on other branches. The view of permanency represents life as being surrounded with unavoidable death, the principle of periodicity, on the contrary, follows the idea of resurrection, granting the possibility of future progression for all living beings. At the same time it yields a more hopeful prospect for experimental inquiry. Experience must decide between the two main theories. It demonstrates the existence of polymorphous genera, such as _Draba_ and _Viola_ and hundreds of others. They clearly indicate a previous state of mutability. Their systematic relation is exactly what would be expected, if they were the result of such a period. Perhaps mutability has not wholly ceased in them, but, might be found to survive in some of their members. Such very rich genera however, are not the rule, but are exceptional cases, indicating the rarity of powerful mutative changes. On the other hand, species may remain in a state of constancy during long, apparently during indefinite, ages. [694] Many facts plead in favor of the constancy of species. This principle has always been recognized by systematists. Temporarily the current form of the theory of natural selection has assumed species to be inconstant, ever changing and continuously being improved and adapted to the requirements of the life-conditions. The followers of the theory of descent believed that this conclusion was unavoidable, and were induced to deny the manifest fact that species are constant entities. The mutation theory gives a clew to the final combination of the two contending ideas. Reducing the changeability of the species to distinct and probably short periods, it at once explains how the stability of species perfectly agrees with the principle of descent through modification. On the other hand, the hypothesis of mutative periods is by no means irreconcilable with the observed facts of constancy. Such casual changes can be proved by observations such as those upon the evening-primrose, but it is obvious that a disproof can never be given. The principle grants the present constancy of the vast majority of living forms, and only claims the exceptional occurrence of definite changes. Proofs of the constancy of species have been given in different ways. The high degree of similarity of the individuals of most of our [695] species has never been denied. It is observed throughout extended localities, and during long series of years. Other proofs are afforded by those plants which have been transported to distant localities some time since, but do not exhibit any change as a result of this migration. Widely dispersed plants remain the same throughout their range, provided that they belong to a single elementary species. Many species have been introduced from America into Europe and have spread rapidly and widely. The Canadian horsetail (_Erigeron canadensis_), the evening-primrose and many other instances could be given. They have not developed any special European features after their introduction. Though exposed to other environmental conditions and to competition with other species, they have not succeeded in developing a new character. Such species as proved adequate to the new environment have succeeded, while those which did not have succumbed. Much farther back is the separation of the species which now live both in arctic regions and on the summits of our highest mountaintops. If we compare the alpine flora with the arctic plants, a high degree of similarity at once strikes us. Some forms are quite identical; others are slightly different, manifestly representing elementary species of the same systematic [696] type. Still others are more distant or even belong to different genera. The latter, and even the diverging, though nearly allied, elementary species, do not yield adequate evidence in any direction. They may as well have lived together in the long ages before the separation of the now widely distant floras, or have sprung from a common ancestor living at that time, and subsequently have changed their habits. After excluding these unreliable instances, a good number of species remain, which are quite the same in the arctic and alpine regions and on the summits of distant mountain ranges. As no transportation over such large distances can have brought them from one locality to the other, no other explanation is left than that they have been wholly constant and unchanged ever since the glacial period which separated them. Obviously they must have been subjected to widely changing conditions. The fact of their stability through all these outward changes is the best proof that the ordinary external conditions do not necessarily have an influence on specific evolution. They may have such a result in some instances, in others they obviously have not. Many arctic forms bearing the specific name of _alpinus_ justify this conclusion. _Astragalus alpinus_, _Phleum alpinum_, _Hieracium alpinum_ and [697] others from the northern parts of Norway may be cited as examples. Thus Primula imperialis has been found in the Himalayas, and many other plants of the high mountains of Java, Ceylon and northern India are identical forms. Some species from the Cameroons and from Abyssinia have been found on the mountains of Madagascar. Some peculiar Australian types are represented on the summit of Kini Balu in Borneo. None of these species, of course, are found in the intervening lowlands, and the only possible explanation of their identity is the conception of a common post-glacial origin, coupled with complete stability. This stability is all the more remarkable as nearly allied but slightly divergent forms have also been reported from almost all of these localities. Other evidence is obtained by the comparison of ancient plants with their living representatives. The remains in tombs of ancient Egypt have always afforded strong support of the views of the adherents of the theory of stability, and to my mind they still do so. The cereals and fruits and even the flowers and leaves in the funeral wreaths of Rameses and Amen-Hotep are the same that are still now cultivated in Egypt. Nearly a hundred or more species have been identified. Flowers of _Acacia_, leaves of _Mimusops_, [698] petals of _Nymphaea_ may be cited as instances, and they are as perfectly preserved as the best herbarium-specimens of the present time. The petals and stamens retain their original colors, displaying them as brightly as is consistent with their dry state. Paleontologic evidence points to the same conclusion. Of course the remains are incomplete, and rarely adequate for a close comparison. The range of fluctuating variability should be examined first, but the test of elementary species given by their constancy from seed cannot, of course, be applied. Apart from these difficulties, paleontologists agree in recognizing the very great age of large numbers of species. It would require a too close survey of geologic facts to go into details on this point. Suffice it to say that in more recent Tertiary deposits many species have been identified with living forms. In the Miocene period especially, the similarity of the types of phanerogamic plants with their present offspring, becomes so striking that in a large number of cases specific distinctions rest in greater part on theoretical conceptions rather than on real facts. For a long time the idea prevailed that the same species could not have existed through more than one geologic period. Many distinctions founded on this belief have since had to be abandoned. [699] Species of algae belonging to the well-preserved group of the diatoms, are said to have remained unchanged from the Carboniferous period up to the present time. Summing up the results of this very hasty survey, we may assert that species remain unchanged for indefinite periods, while at times they are in the alternative condition. Then at once they produce new forms often in large numbers, giving rise to swarms of subspecies. All facts point to the conclusion that these periods of stability and mutability alternate more or less regularly with one another. Of course a direct proof of this view cannot, as yet, be given, but this conclusion is forced upon us by a consideration of known facts bearing on the principle of constancy and evolution. If we are right in this general conception, we may ask further, what is to be the exact place of our group of new evening-primroses in this theory? In order to give an adequate answer, we must consider the whole range of the observations from a broader point of view. First of all it is evident that the real mutating period must be assumed to be much longer than the time covered by my observations. Neither the beginning nor the end have been seen. It is quite obvious that _Oenothera lamarckiana_ was in a mutating condition when I first [700] saw it, seventeen years ago. How long had it been so? Had it commenced to mutate after its introduction into Europe, some time ago, or was it already previously in this state? It is as yet impossible to decide this point. Perhaps the mutable state is very old, and dates from the time of the first importation of the species into Europe. Apart from all such considerations the period of the direct observations, and the possible duration of the mutability through even more than a century, would constitute only a moment, if compared with the whole geologic time. Starting from this conception the pedigree of our mutations must be considered as only one small group. Instead of figuring a fan of mutants for each year, we must condense all the succeeding swarms into one single fan, as might be done also for _Draba verna_ and other polymorphous species. In _Oenothera_ the main stem is prolonged upwards beyond the fan; in the others the main stem is lacking or at least undiscernable, but this feature manifestly is only of secondary importance. We might even prefer the image of a fan, adjusted laterally to a stem, which itself is not interrupted by this branch. On this principle two further considerations are to be discussed. First the structure of the [701] fan itself, and secondly the combination of succeeding fans into a common genealogic tree. The composition of the fan as a whole includes more than is directly indicated by the facts concerning the birth of new species. They arise in considerable quantities, and each of them in large numbers of individuals, either in the same or in succeeding years. This multiple origin must obviously have the effect of strengthening the new types, and of heightening their chances in the struggle for life. Arising in a single specimen they would have little chance of success, since in the field among thousands of seeds perhaps one only survives and attains complete development. Thousands or at least hundreds of mutated seeds are thus required to produce one mutated individual, and then, how small are its chances of surviving! The mutations proceed in all directions, as I have pointed out in a former lecture. Some are useful, others might become so if the circumstances were accidentally changed in definite directions, or if a migration from the original locality might take place. Many others are without any real worth, or even injurious. Harmless or even slightly useless ones have been seen to maintain themselves in the field during the seventeen years of my research, as proved by _Oenothera laevifolia_ and _Oenothera_ [702] _brevistylis_. Most of the others quickly disappear. This failure of a large part of the productions of nature deserves to be considered at some length. It may be elevated to a principle, and may be made use of to explain many difficult points of the theory of descent. If, in order to secure one good novelty, nature must produce ten or twenty or perhaps more bad ones at the same time, the possibility of improvements coming by pure chance must be granted at once. All hypotheses concerning the direct causes of adaptation at once become superfluous, and the great principle enunciated by Darwin once more reigns supreme. In this way too, the mutation-period of the evening-primrose is to be considered as a prototype. Assuming it as such provisionally, it may aid us in arranging the facts of descent so as to allow of a deeper insight and a closer scrutiny. All swarms of elementary species are the remains of far larger initial groups. All species containing only a few subspecies may be supposed to have thrown off at the outset far more numerous lateral branches, out of which however, the greater part have been lost, being unfit for the surrounding conditions. It is the principle of the struggle for life between elementary species, followed by the survival of the [703] fittest, the law of the selection of species, which we have already laid stress upon more than once. Our second consideration is also based upon the frequent repetition of the several mutations. Obviously a common cause must prevail. The faculty of producing _nanella_ or _lata_ remains the same through all the years. This faculty must be one and the same for all the hundreds of mutative productions of the same form. When and how did it originate? At the outset it must have been produced in a latent condition, and even yet it must be assumed to be continuously present in this state, and only to become active at distant intervals. But it is manifest that the original production of the characters of _Oenothera gigas_ was a phenomenon of far greater importance than the subsequent accidental transition of this quality into the active state. Hence the conclusion that at the beginning of each series of analogous mutations there must have been one greater and more intrinsic mutation, which opened the possibility to all its successors. This was the origination of the new character itself, and it is easily seen that this incipient change is to be considered as the real one. All others are only its visible expressions. Considering the mutative period of our evening-primrose [704] as one unit-stride section in the great genealogic tree, this period includes two nearly related, but not identical changes. One is the production of new specific characters in the latent condition, and the other is the bringing of them to light and putting them into active existence. These two main factors are consequently to be assumed in all hypothetic conceptions of previous mutative periods. Are all mutations to be considered as limited to such periods? Of course not. Stray mutations may occur as well. Our knowledge concerning this point is inadequate for any definite statement. Swarms of variable species are easily recognized, if the remnants are not too few. But if only one or two new species have survived, how can we tell whether they have originated-alone or together with others. This difficulty is still more pronounced in regard to paleontologic facts, as the remains of geologic swarms are often found, but the absence of numerous mutations can hardly be proved in any case. I have more than once found occasion to lay stress on the importance of a distinction between progressive and retrograde mutations in previous lectures. All improvement is, of course, by the first of these modes of evolution, but apparent losses of organs or qualities are [705] perhaps of still more universal occurrence. Progression and regression are seen to go hand in hand everywhere. No large group and probably even no genus or large species has been evolved without the joint agency of these two great principles. In the mutation-period of the evening-primroses the observed facts give direct support to this conclusion, since some of the new species proved, on closer inspection, to be retrograde varieties, while others manifestly owe their origin to progressive steps. Such steps may be small and in a wrong direction; notwithstanding this they may be due to the acquisition of a wholly new character and therefore belong to the process of progression at large. Between them however, there is a definite contrast, which possibly is in intimate connection with the question of periodic and stray mutations. Obviously each progressive change is dependent upon the production of a new character, for whenever this is lacking, no such mutation is possible. Retrograde changes, on the other hand, do not require such elaborate preliminary work. Each character may be converted into the latent condition, and for all we know, a special preparation for this purpose is not at all necessary. It is readily granted that such special preparation may occur, because the [706] great numbers in which our dwarf variety of the _Oenothera_ are yearly produced are suggestive of such a condition. On the other hand, the _laevifolia_ and _brevistylis_ mutations have not been repeated, at least not in a visible way. From this discussion we may infer that it is quite possible that a large part of the progressive changes, and a smaller part of the retrograde mutations, are combined into groups, owing their origin to common external agencies. The periods in which such groups occur would constitute the mutative periods. Besides them the majority of the retrograde changes and some progressive steps might occur separately, each being due to some special cause. Degressive mutations, or those which arise by the return of latent qualities to activity, would of course belong with the latter group. This assumption of a stray and isolated production of varieties is to a large degree supported by experience in horticulture. Here there are no real swarms of mutations. Sudden leaps in variability are not rare, but then they are due to hybridization. Apart from this mixture of characters, varieties as a rule appear separately, often with intervals of dozens of years, and without the least suggestion of a common cause. It is quite superfluous to go into details, as we have dealt with the horticultural [707] mutations at sufficient length on a previous occasion. Only the instance of the peloric toadflax might be recalled here, because the historic and geographic evidence, combined with the results of our pedigree-experiment, plainly show that peloric mutations are quite independent of any periodic condition. They may occur anywhere in the wide range of the toad-flax, and the capacity of repeatedly producing them has lasted some centuries at least, and is perhaps even as old as the species itself. Leaving aside such stray mutations, we may now consider the probable constitution of the great lines of the genealogic tree of the evening primroses, and of the whole vegetable and animal kingdom at large. The idea of drawing up a pedigree for the chief groups of living organisms is originally due to Haeckel, who used this graphic method to support the Darwinian theory of descent. Of course, Haeckel's genealogic trees are of a purely hypothetic nature, and have no other purpose than to convey a clear conception of the notion of descent, and of the great lines of evolution at large. Obviously all details are subject to doubt, and many have accordingly been changed by his successors. These changes may be considered as partial improvements, and the somewhat picturesque form of Haeckel's pedigree might well be replaced by [708] more simple plans. But the changes have by no means removed the doubts, nor have they been able to supplant the general impression of distinct groups, united by broad lines. This feature is very essential, and it is easily seen to correspond with the conception of swarms, as we have deduced it from the study of the lesser groups. Genealogic trees are the result of comparative studies; they are far removed from the results of experimental inquiry concerning the origin of species. What are the links which bind them together? Obviously they must be sought in the mutative periods, which have immediately preceded the present one. In the case of the evening-primrose the systematic arrangement of the allied species readily guides us in the delimitations of such periods. For manifestly the species of the large genus of _Oenothera_ are grouped in swarms, the youngest or most recent of which we have under observation. Its immediate predecessor must have been the subgenus _Onagra_, which is considered by some authors as consisting of a single systematic species, _Oenothera biennis_. Its multifarious forms point to a common origin, not only morphologically but also historically. Following this line backward or downward we reach another apparent mutation-period, which includes the origin of [709] the group called _Oenothera_, with a large number of species of the same general type as the _Onagra-forms, Still farther downward comes the old genus _Oenothera_ itself, with numerous subgenera diverging in sundry characters and directions. Proceeding still farther we might easily construct a main stem with numerous succeeding fans of lateral branches, and thus reach, from our new empirical point of view, the theoretical conclusion already formulated. Paleontologic facts readily agree with this conception. The swarms of species and varieties are found to succeed one another like so many stories. The same images are repeated, and the single stories seem to be connected by the main stems, which in each tier produce the whole number of allied forms. Only a few prevailing lines are prolonged through numerous geologic periods; the vast majority of the lateral branches are limited each to its own storey. It is simply the extension of the pedigree of the evening-primroses backward through ages, with the same construction and the same leading features. There can be no doubt that we are quite justified in assuming that evolution has followed the same general laws through the whole duration of life on earth. Only a moment of their lifetime is disclosed to us, but it [710] is quite sufficient to enable us to discern the laws and to conjecture the outlines of the whole scheme of evolution. A grave objection which has, often, and from the very outset, been urged against Darwin's conception of very slow and nearly imperceptible changes, is the enormously long time required. If evolution does not proceed any faster than what we can see at present, and if the process must be assumed to have gone on in the same slow manner always, thousands of millions of years would have been needed to develop the higher types of animals and plants from their earliest ancestors. Now it is not at all probable that the duration of life on earth includes such an incredibly long time. Quite on the contrary the lifetime of the earth seems to be limited to a few millions of years. The researches of Lord Kelvin and other eminent physicists seem to leave no doubt on this point. Of course all estimates of this kind are only vague and approximate, but for our present purposes they may be considered as sufficiently exact. In a paper published in 1862 Sir William Thomson (now Lord Kelvin) first endeavored to show that great limitation had to be put upon the enormous demand for time made by Lyell, Darwin and other biologists. From a consideration [711] of the secular cooling of the earth, as deduced from the increasing temperature in deep mines, he concluded that the entire age of the earth must have been more than twenty and less than forty millions of years, and probably much nearer twenty than forty. His views have been much criticised by other physicists, but in the main they have gained an ever-increasing support in the way of evidence. New mines of greater depth have been bored, and their temperatures have proved that the figures of Lord Kelvin are strikingly near the truth. George Darwin has calculated that the separation of the moon from the earth must have taken place some fifty-six millions of years ago. Geikie has estimated the existence of the solid crust of the earth at the most as a hundred million years. The first appearance of the crust must soon have been succeeded by the formation of the seas, and a long time does not seem to have been required to cool the seas to such a degree that life became possible. It is very probable that life originally commenced in the great seas, and that the forms which are now usually included in the plankton or floating-life included the very first living beings. According to Brooks, life must have existed in this floating condition during long primeval epochs, and evolved nearly all the main branches of the animal and vegetable kingdom [712] before sinking to the bottom of the sea, and later producing the vast number of diverse forms which now adorn the sea and land. All these evolutions, however, must have been very rapid, especially at the beginning, and together cannot have taken more time than the figures given above. The agency of the larger streams, and the deposits which they bring into the seas, afford further evidence. The amount of dissolved salts, especially of sodium chloride, has been made the subject of a calculation by Joly, and the amount of lime has been estimated by Eugene Dubois. Joly found fifty-five and Dubois thirty-six millions of years as the probable duration of the age of the rivers, and both figures correspond to the above dates as closely as might be expected from the discussion of evidence so very incomplete and limited. All in all it seems evident that the duration of life does not comply with the demands of the conception of very slow and continuous evolution. Now it is easily seen, that the idea of successive mutations is quite independent of this difficulty. Even assuming that some thousands of characters must have been acquired in order to produce the higher animals and plants of the present time, no valid objection is raised. The demands of the biologists and the results of [713] the physicists are harmonized on the ground of the theory of mutation. The steps may be surmised to have never been essentially larger than in the mutations now going on under our eyes, and some thousands of them may be estimated as sufficient to account for the entire organization of the higher forms. Granting between twenty and forty millions of years since the beginning of life, the intervals between two successive mutations may have been centuries and even thousands of years. As yet there has been no objection cited against this assumption, and hence we see that the lack of harmony between the demands of biologists and the results of the physicists disappears in the light of the theory of mutation. Summing up the results of this discussion, we may justifiably assert that the conclusions derived from the observations and experiments made with evening-primroses and other plants in the main agree satisfactorily with the inferences drawn from paleontologic, geologic and systematic evidence. Obviously these experiments are wonderfully supported by the whole of our knowledge concerning evolution. For this reason the laws discovered in the experimental garden may be considered of great importance, and they may guide us in our further inquiries. Without doubt many minor [714] points are in need of correction and elaboration, but such improvements of our knowledge will gradually increase our means of discovering new instances and, new proofs. The conception of mutation periods producing swarms of species from time to time, among which only a few have a chance of survival, promises to become the basis for speculative pedigree-diagrams, as well as for experimental investigations. [715] LECTURE XXV GENERAL LAWS OF FLUCTUATION The principle of unit-characters and of elementary species leads at once to the recognition of two kinds of variability. The changes of wider amplitude consist of the acquisition of new units, or the loss of already existing ones. The lesser variations are due to the degree of activity of the units themselves. Facts illustrative of these distinctions were almost wholly lacking at the time of the first publication of Darwin's theories. It was a bold conception to point out the necessity for such distinction on purely theoretical grounds. Of course some sports were well known and fluctuations were evident, but no exact analysis of the details was possible, a fact that was of great importance in the demonstration of the theory of descent. The lack of more definite knowledge upon this matter was keenly felt by Darwin, [716] and exercised much influence upon his views at various times. Quetelet's famous discovery of the law of fluctuating variability changed the entire situation and cleared up many difficulties. While a clear conception of fluctuations was thus gained, mutations were excluded from consideration, being considered as very rare, or non-existent. They seemed wholly superfluous for the theory of descent, and very little importance was attached to their study. Current scientific belief in the matter has changed only in recent years. Mendel's law of varietal hybrids is based upon the principle of unit-characters, and the validity of this conception has thus been brought home to many investigators. A study of fluctuating or individual variability, as it was formerly called, is now carried on chiefly by mathematical methods. It is not my purpose to go into details, as it would require a separate course of lectures. I shall consider the limits between fluctuation and mutation only, and attempt to set forth an adequate idea of the principles of the first as far as they touch these limits. The mathematical treatment of the facts is no doubt of very great value, but the violent discussions now going on between mathematicians such as Pearson, Kapteyn and others should warn biologists to abstain [717] from the use of methods which are not necessary for the furtherance of experimental work. Fortunately, Quetelet's law is a very clear and simple one, and quite sufficient for our considerations. It claims that for biologic phenomena the deviations from the average comply with the same laws as the deviations from the average in any other case, if ruled by chance only. The meaning of this assertion will become clear by a further discussion of the facts. First of all, fluctuating variability is an almost universal phenomenon. Every organ and every quality may exhibit it. Some are very variable, while others seem quite constant. Shape and size vary almost indefinitely, and the chemical composition is subject to the same law, as is well known for the amount of sugar in sugar-beets. Numbers are of course less liable to changes, but the numbers of the rays of umbels, or ray-florets in the composites, of pairs of blades in pinnate leaves, and even of stamens and carpels are known to be often exceedingly variable. The smaller numbers however, are more constant, and deviations from the quinate structure of flowers are rare. Complicated structures are generally capable of only slight deviations. From a broad point of view, fluctuating variability [718] falls under two heads. They obey quite the same laws and are therefore easily confused, but with respect to questions of heredity they should be carefully separated. They are designated by the terms individual and partial fluctuation. Individual variability indicates the differences between individuals, while partial variability is limited to the deviations shown by the parts of one organism from the average structure. The same qualities in some cases vary individually and in others partially. Even stature, which is as markedly individual for annual and biennial plants as it is for man, becomes partially variant in the case of perennial herbs with numbers of stems. Often a character is only developed once in the whole course of evolution, as for instance, the degree of connation of the seed-leaves in tricotyls and in numerous cases it is impossible to tell whether a character is individual or partial. Consequently such minute details are generally considered to have no real importance for the hereditary transmission of the character under discussion. Fluctuations are observed to take place only in two directions. The quality may increase or decrease, but is not seen to vary in any other way. This rule is now widely established by numerous investigations, and is fundamental to [719] the whole method of statistical investigation. It is equally important for the discussion of the contrast between fluctuations and mutations, and for the appreciation of their part in the general progress of organization. Mutations are going on in all directions, producing, if they are progressive, something quite new every time. Fluctuations are limited to increase and decrease of what is already available. They may produce plants with higher stems, more petals in the flowers, larger and more palatable fruits, but obviously the first petal and the first berry, cannot have originated by the simple increase of some older quality. Intermediates may be found, and they may mark the limit, but the demonstration of the absence of a limit is quite another question. It would require the two extremes to be shown to belong to one unit, complying with the simple law of Quetelet. Nourishment is the potent factor of fluctuating variability. Of course in thousands of cases our knowledge is not sufficient to allow us to analyze this relation, and a number of phases of the phenomenon have been discovered only quite recently. But the fact itself is thoroughly manifest, and its appreciation is as old as horticultural science. Knight, who lived at the beginning of the last century, has laid great stress upon it, and it has since influenced practice in a [720] large measure. Moreover, Knight pointed out more than once that it is the amount of nourishment, not the quality of the various factors, that exercises the determinative influence. Nourishment is to be taken in the widest sense of the word, including all favorable and injurious elements. Light and temperature, soil and space, water and salts are equally active, and it is the harmonious cooperation of them all that rules growth. We treated this important question at some length, when dealing with the anomalies of the opium-poppies, consisting of the conversion of stamens into supernumerary pistils. The dependency upon external influences which this change exhibited is quite the same as that shown by fluctuating variability at large. We inquired into the influence of good and bad soil, of sunlight and moisture and of other concurrent factors. Especial emphasis was laid upon the great differences to which the various individuals of the same lot may be exposed, if moisture and manure differ on different portions of the same bed in a way unavoidable even by the most careful preparation. Some seeds germinate on moist and rich spots, while their neighbors are impeded by local dryness, or by distance from manure. Some come to light on a sunny day, and increase their first leaves rapidly, while on [721] the following day the weather may be unfavorable and greatly retard growth. The individual differences seem to be due, at least in a very great measure, to such apparent trifles. On the other hand partial differences are often manifestly due to similar causes. Considering the various stems of plants, which multiply themselves by runners or by buds on the roots, the assertion is in no need of further proof. The same holds good for all cases of artificial multiplication by cuttings, or by other vegetative methods. But even if we limit ourselves to the leaves of a single tree, or the branches of a shrub, or the flowers on a plant, the same rule prevails. The development of the leaves is dependent on their position, whether inserted on strong or weak branches, exposed to more or less light, or nourished by strong or weak roots. The vigor of the axillary buds and of the branches which they may produce is dependent upon the growth and activity of the leaves to which the buds are axillary. This dependency on local nutrition leads to the general law of periodicity, which, broadly speaking, governs the occurrence of the fluctuating deviations of the organs. This law of periodicity involves the general principle that every axis, as a rule, increases in strength when [722] growing, but sooner or later reaches a maximum and may afterwards decrease. This periodic augmentation and declination is often boldly manifest, though in other cases it may be hidden by the effect of alternate influences. Pinnate leaves generally have their lower blades smaller than the upper ones, the longest being seen sometimes near the apex and sometimes at a distance from it. Branches bearing their leaves in two rows often afford quite as obvious examples, and shoots in general comply with the same rule. Germinating plants are very easy of observation on this point. When they are very weak they produce only small leaves. But their strength gradually increases and the subsequent organs reach fuller dimensions until the maximum is attained. The phenomenon is so common that its importance is usually overlooked. It should be considered as only one instance of a rule, which holds good for all stems and all branches, and which is everywhere dependent on the relation of growth to nutrition. The rule of periodicity not only affects the size of the organs, but also their number, whenever these are largely variable. Umbellate plants have numerous rays on the umbels of strong stems, but the number is seen to decrease and to become very small on the weakest lateral [723] branches. The same holds good for the number of ray-florets in the flower-heads of the composites, even for the number of stigmas on the ovaries of the poppies, which on weak branches may be reduced to as few as three or four. Many other instances could be given. One of the best authenticated cases is the dependency of partial fluctuation on the season and on the weather. Flowers decline when the season comes to an end, become smaller and less brightly colored. The number of ray-florets in the flower-heads is seen to decrease towards the fall. Extremes become rarer, and often the deviations from the average seem nearly to disappear. Double flowers comply with this rule very closely, and many other cases will easily occur to any student of nature. Of course, the relation to nourishment is different for individual and partial fluctuations. Concerning the first, the period of development of the germ within the seed is decisive. Even the sexual cells may be in widely different conditions at the moment of fusion, and perhaps this state of the sexual cells includes the whole matter of the decision for the average characters of the new individual. Partial fluctuation commences as soon as the leaves and buds begin to form, and all later changes in nutrition can only cause partial differences. All leaves, [724] buds, branches, and flowers must come under the influence of external conditions during the juvenile period, and so are liable to attain a development determined in part by the action of these factors. Before leaving these general considerations, we must direct our attention to the question of utility. Obviously, fluctuating variability is a very useful contrivance, in many cases at least. It appears all the more so, as its relation to nutrition becomes manifest. Here two aspects are intimately combined. More nutrient matter produces larger leaves and these are in their turn more fit to profit by the abundance of nourishment. So it is with the number of flowers and flower-groups, and even with the numbers of their constituent organs. Better nourishment produces more of them, and thereby makes the plant adequate to make a fuller use of the available nutrient substances. Without fluctuation such an adjustment would hardly be possible, and from all our notions of usefulness in nature, we therefore must recognize the efficiency of this form of variability. In other respects the fluctuations often strike us as quite useless or even as injurious. The numbers of stamens, or of carpels are dependent on nutrition, but their fluctuation is not known to have any attraction for the visiting insects. [725] If the deviations become greater, they might even become detrimental. The flowers of the St. Johnswort, or _Hypericum perforatum_, usually have five petals, but the number varies from three to eight or more. Bees could hardly be misled by such deviations. The carpels of buttercups and columbines, the cells in the capsules of cotton and many other plants are variable in number. The number of seeds is thereby regulated in accordance with the available nourishment, but whether any other useful purpose is served, remains an open question. Variations in the honey-guides or in the pattern of color-designs might easily become injurious by deceiving insects, and such instances as the great variability of the spots on the corolla of some cultivated species of monkey-flowers, for instance, the _Mimulus quinquevulnerus_, could hardly be expected to occur in wild plants. For here the dark brown spots vary between nearly complete deficiency up to such predominancy as almost to hide the pale yellow ground-color. After this hasty survey of the causes of fluctuating variability, we now come to a discussion of Quetelet's law. It asserts that the deviations from the average obey the law of probability. They behave as if they were dependent on chance only. Everyone knows that the law of Quetelet can [726] be demonstrated the most readily by placing a sufficient number of adult men in a row, arranging them according to their size. The line passing over their heads proves to be identical with that given by the law of probability. Quite in the same way, stems and branches, leaves and petals and even fruits can be arranged, and they will in the main exhibit the same line of variability. Such groups are very striking, and at the first glance show that the large majority of the specimens deviate from the mean only to a very small extent. Wider deviations are far more rare, and their number lessens, the greater the deviation, as is shown by the curvature of the line. It is almost straight and horizontal in the middle portion, while at the ends it rapidly declines, going sharply downward at one extreme and upward at the other. It is obvious however, that in these groups the leaves and other organs could conveniently be replaced by simple lines, indicating their size. The result would be quite the same, and the lines could be placed at arbitrary, but equal distances. Or the sizes could be expressed by figures, the compliance of which with the general law could be demonstrated by simple methods of calculation. In this manner the variability of different organs can easily be compared. Another method of demonstration consists in [727] grouping the deviations into previously fixed divisions. For this purpose the variations are measured by standard units, and all the instances that fall between two limits are considered to constitute one group. Seeds and small fruits, berries and many other organs may conveniently be dealt with in this way. As an example we take ordinary beans and select them according to their size. This can be done in different ways. On a small piece of board a long wedge-shaped slit is made, into which seeds are pushed as far as possible. The margin of the wedge is calibrated in such a manner that the figures indicate the width of the wedge at the corresponding place. By this device the figure up to which a bean is pushed at once shows its length. Fractions of millimeters are neglected, and the beans, after having been measured, are thrown into cylindrical glasses of the same width, each glass receiving only beans of equal length. It is clear that by this method the height to which beans fill the glasses is approximately a measure of their number. If now the glasses are put in a row in the proper sequence, they at once exhibit the shape of a line which corresponds to the law of chance. In this case however, the line is drawn in a different manner from the first. It is to be pointed out that the glasses may be replaced by lines indicating [728] the height of their contents, and that, in order to reach a more easy and correct statement, the length of the lines may simply be made proportionate to the number of the beans in each glass. If such lines are erected on a common base and at equal distances, the line which unites their upper ends will be the expression of the fluctuating variability of the character under discussion. The same inquiry may be made with other seeds, with fruits, or other organs. It is quite superfluous to arrange the objects themselves, and it is sufficient to arrange the figures indicating their value. In order to do this a basal line is divided into equal parts, the demarcations corresponding to the standard-units chosen for the test. The observed values are then written above this line, each finding its place between the two demarcations, which include its value. It is very interesting and stimulating to construct such a group. The first figures may fall here and there, but very soon the vertical rows on the middle part of the basal line begin to increase. Sometimes ten or twenty measurements will suffice to make the line of chance appear, but often indentations will remain. With the increasing number of the observations the irregularities gradually [729] disappear, and the line becomes smoother and more uniformly curved. This method of arranging the figures directly on a basal line is very convenient, whenever observations are made in the field or garden. Very few instances need be recorded to obtain an appreciation of the mean value, and to show what may be expected from a continuance of the test. The method is so simple and so striking, and so wholly independent of any mathematical development that it should be applied in all cases in which it is desired to ascertain the average value of any organ, and the measure of the attendant deviations. I cite an instance, secured by counting the ray-florets on the flower-heads of the corn-marigold or _Chrysanthemum segetum_. It was that, by which I was enabled to select the plant, which afterwards showed the first signs of a double head. I noted them in this way; 47 47 52 41 54 68 44 50 62 75 36 45 58 65 72 __ 99 Of course the figures might be replaced in this work by equidistant dots or by lines, but experience teaches that the chance of making mistakes is noticeably lessened by writing down [730] the figures themselves. Whenever decimals are made use of it is obviously the best plan to keep the figures themselves. For afterwards it often becomes necessary to arrange them according to a somewhat different standard. Uniting the heads of the vertical rows of figures by a line, the form corresponding to Quetelet's law is easily seen. In the main it is always the same as the line shown by the measurements of beans and seeds. It proves a dense crowding of the single instances around the average, and on both sides of the mass of the observations, a few wide deviations. These become more rare in proportion to the amount of their divergency. On both sides of the average the line begins by falling very rapidly, but then bends slowly so as to assume a nearly horizontal direction. It reaches the basal line only beyond the extreme instances. It is quite evident that all qualities, which can be expressed by figures, may be treated in this way. First, of all the organs occurring in varying numbers, as for instance the ray-florets of composites, the rays of umbels, the blades of pinnate and palmate leaves, the numbers of veins, etc., are easily shown to comply with the same general rule. Likewise the amount of chemical substances can be expressed in percentage numbers, as is done on a large [731] scale with sugar in beets and sugar-cane, with starch in potatoes and in other instances. These figures are also found to follow the same law. All qualities which are seen to increase and to decrease may be dealt with in the same manner, if a standard unit for their measurement can be fixed. Even the colors of flowers may not escape our inquiry. If we now compare the lines, compiled from the most divergent cases, they will be found to exhibit the same features in the main. Ordinarily the curve is symmetrical, the line sloping down on both sides after the same manner. But it is not at all rare that the inclination is steep on one side and gradual on the other. This is noticeably the case if the observations relate to numbers, the average of which is near zero. Here of course the allowance for variation is only small on one side, while it may increase with out distinct limits on the alternate slope. So it is for instance with the numbers of ray-florets in the example given on p. 729. Such divergent cases, however, are to be considered as exceptions to the rule, due to some unknown cause. Heretofore we have discussed the empirical side of the problem only. For the purpose of experimental study of questions of heredity this is ordinarily quite sufficient. The inquiry [732] into the phenomenon of regression, or of the relation of the degree of deviation of the progeny to that of their parents, and the selection of extreme instances for multiplication are obviously independent of mathematical considerations. On the other hand an important inquiry lies in the statistical treatment of these phenomena, and such treatment requires the use of mathematical methods. Statistics however, are not included in the object of these lectures, and therefore I shall refrain from an explanation of the method of their preparation and limit myself to a general comparison of the observed lines with the law of chance. Before going into the details, it should be repeated once more that the empirical result is quite the same for individual and for partial fluctuations. As a rule, the latter occur in far greater number, and are thus more easily investigated, but individual or personal averages have also been studied. Newton discovered that the law of chance can be expressed by very simple mathematical calculations. Without going into details, we may at once state that these calculations are based upon his binomium. If the form (a + b) is calculated for some value of the exponent, and if the values of the coefficients after development are alone considered, they yield the basis [733] for the construction of what is called the line or curve of probability. For this construction the coefficients are used as ordinates, the length of which is to be made proportionate to their value. If this is done, and the ordinates are arranged at equal distances, the line which unites their summits is the desired curve. At first glance it exhibits a form quite analogous to the curves of fluctuating variability, obtained by the measurements of beans and in other instances. Both lines are symmetrical and slope rapidly down in the region of the average, while with increasing distance they gradually lose their steep inclination, becoming nearly parallel to the base at their termination. This similarity between such empirical and theoretical lines is in itself an empirical fact. The causes of chance are assumed to be innumerable, and the whole calculation is based on this assumption. The causes of the fluctuations of biological phenomena have not as yet been critically examined to such an extent as to allow of definite conceptions. The term nourishment manifestly includes quite a number of separate factors, as light, space, temperature, moisture, the physical and chemical conditions of the soil and the changes of the weather. Without doubt the single factors are very numerous, but whether they are numerous enough to be treated [734] as innumerable, and thereby to explain the laws of fluctuations, remains uncertain. Of course the easiest way is to assume that they combine in the same manner as the causes of chance, and that this is the ground of the similarity of the curves. On the other hand, it is manifestly of the highest importance to inquire into the part the several factors play in the determination of the curves. It is not at all improbable that some of them have a larger influence on individual, and others on partial, fluctuations. If this were the case, their importance with respect to questions of heredity might be widely different. In the present state of our knowledge the fluctuation-curves do not contribute in any large measure to an elucidation of the causes. Where these are obvious, they are so without statistics, exactly as they were, previous to Quetelet's discovery. In behalf of a large number of questions concerning heredity and selection, it is very desirable to have a somewhat closer knowledge of these curves. Therefore I shall try to point out their more essential features, as far as this can be done without mathematical calculations. At a first glance three points strike us, the average or the summit of the curve, and the extremes. If the general shape is once denoted by the results of observations or by the coefficients [735] of the binomium, all further details seem to depend upon them. In respect to the average this is no doubt the case; it is an empirical value without need of any further discussion. The more the number of the observations increases, the more assured and the more correct is this mean value, but generally it is the same for smaller and for larger groups of observations. This however, is not the case with the extremes. It is quite evident that small groups have a chance of containing neither of them. The more the number of the observations increases, the larger is the chance of extremes. As a rule, and excluding exceptional cases, the extreme deviations will increase in proportion to the number of cases examined. In a hundred thousand beans the smallest one and the largest one may be expected to differ more widely from one another than in a few hundred beans of the same sample. Hence the conclusion that extremes are not a safe criterion for the discussion of the curves, and not at all adequate for calculations, which must be based upon more definite values. A real standard is afforded by the steepness of the slope. This may be unequal on the two sides of one curve, and likewise it may differ for different cases. This steepness is usually measured by means of a point on the half curve and [736 ] for this purpose a point is chosen which lies exactly half way between the average and the extreme. Not however half way with respect to the amplitude of the extreme deviation, for on this ground it would partake of the uncertainty of the extreme itself. It is the point on the curve which is surpassed by half the number, and not reached by the other half of the number of the observations included in the half of the curve. This point corresponds to the important value called the probable error, and was designated by Galton as the quartile. For it is evident that the average and the two quartiles divide the whole of the observations into four equal parts. Choosing the quartiles as the basis for calculations we are independent of all the secondary causes of error, which necessarily are inherent in the extremes. At a casual examination, or for demonstrative purposes, the extremes may be prominent, but for all further considerations the quartiles are the real values upon which to rest calculations. Moreover if the agreement with the law of probability is once conceded, the whole curve is defined by the average and the quartiles, and the result of hundreds of measurements or countings may be summed up in three, or, in [737] the case of symmetrical curves, perhaps in two figures. Also in comparing different curves with one another, the quartiles are of great importance. Whenever an empirical fluctuation-curve is to be compared with the theoretical form, or when two or more cases of variability are to be considered under one head, the lines are to be drawn on the same base. It is manifest that the averages must be brought upon the same ordinate, but as to the steepness of the line, much depends on the manner of plotting. Here we must remember that the mutual distance of the ordinates has been a wholly arbitrary one in all our previous considerations. And so it is, as long as only one curve is considered at a time. But as soon as two are to be compared, it is obvious that free choice is no longer allowed. The comparison must be made on a common basis, and to this effect the quartiles must be brought together. They are to lie on the same ordinates. If this is done, each division of the base corresponds to the same proportionate number of individuals, and a complete comparison is made possible. On the ground of such a comparison we may thus assert that, fluctuations, however different the organs or qualities observed, are the same whenever their curves are seen to overlap one [738] another. Furthermore, whenever an empirical curve agrees in this manner with the theoretical one, the fluctuation complies with Quetelet's law, and may be ascribed to quite ordinary and universal causes. But if it seems to diverge from this line, the cause of this divergence should be inquired into. Such abnormal curves occur from time to time, but are rare. Unsymmetrical instances have already been alluded to, and seem to be quite frequent. Another deviation from the rule is the presence of more than one summit. This case falls under two headings. If the ray florets of a composite are counted, and the figures brought into a curve, a prominent summit usually corresponds to the average. But next to this, and on both sides, smaller summits are to be seen. On a close inspection these summits are observed to fall on the same ordinates, on which, in the case of allied species, the main apex lies. The specific character of one form is thus repeated as a secondary character on an allied species. Ludwig discovered that these secondary summits comply with the rule discovered by Braun and Schimper, stating the relation of the subsequent figures of the series. This series gives the terms of the disposition of leaves in general, and of the bracts and flowers on the composite flower [739] heads in our particular case. It is the series to which we have already alluded when dealing with the arrangement of the leaves on the twisted teasels. It commences with 1 and 2 and each following figure is equal to the sum of its two precedents. The most common figures are 3, 5, 8, 13, 18, 21, higher cases seldom coming under observation. Now the secondary summits of the ray-curves of the composites are seen to agree, as a rule, with these figures. Other instances could readily be given. Our second heading includes those cases which exhibit two summits of equal or nearly equal height. Such cases occur when different races are mixed, each retaining its own average and its own curve-summit. We have already demonstrated such a case when dealing with the origin of our double corn-chrysanthemum. The wild species culminates with 13 rays, and the grandiflorum variety with 21. Often the latter is found to be impure, being mixed with the typical species to a varying extent. This is not easily ascertained by a casual inspection of the cultures, but the true condition will promptly betray itself, if curves are constructed. In this way curves may in many instances be made use of to discover mixed races. Double curves may also result from the investigation [740] of true double races, or ever-sporting varieties. The striped snapdragon shows a curve of its stripes with two summits, one corresponding to the average striped flowers, and the other to the pure red ones. Such cases may be discovered by means of curves, but the constituents cannot be separated by culture-experiments. A curious peculiarity is afforded by half curves. The number of petals is often seen to vary only in one direction from what should be expected to be the mean condition. With buttercups and brambles and many others there is only an increase above the typical five; quaternate flowers are wanting or at least are very rare. With weigelias and many others the number of the tips of the corolla varies downwards, going from five to four and three. Hundreds of flowers show the typical five, and determine the summit of the curve. This drops down on one side only, indicating unilateral variability, which in many cases is due to a very intimate connection of a concealed secondary summit and the main one. In the case of the bulbous buttercup, _Ranunculus bulbosus_, I have succeeded in isolating this secondary summit, although not in a separate variety, but only in a form corresponding to the type of ever-sporting varieties. [741] Recapitulating the results of this too condensed discussion, we may state that fluctuations are linear, being limited to an increase and to a decrease of the characters. These changes are mainly due to differences in nourishment, either of the whole organism or of its parts. In the first case, the deviations from the mean are called individual; they are of great importance for the hereditary characters of the offspring. In the second case the deviations are far more universal and far more striking, but of lesser importance. They are called partial fluctuations. All these fluctuations comply, in the main, with the law of probability, and behave as if their causes were influenced only by chance. [742] LECTURE XXVI ASEXUAL MULTIPLICATION OF EXTREMES Fluctuating variability may be regarded from two different points of view. The multiformity of a bed of flowers is often a desirable feature, and all means which widen the range of fluctuation are therefore used to enhance this feature, and variability affords specimens, which surpass the average, by yielding a better or larger product. In the case of fruits and other cultivated forms, it is of course profitable to propagate from the better specimens only, and if possible only from the very best. Obviously the best are the extremes of the whole range of diverging forms, and moreover the extremes on one side of the group. Almost always the best for practical purposes is that in which some quality is strengthened. Cases occur however, in which it is desirable to diminish an injurious peculiarity as far as possible, and in these instances the opposite extreme is the most profitable one. These considerations lead us to a discussion [743] of the results of the choice of extremes, which it may be easily seen is a matter of the greatest practical importance. This choice is generally designated as selection, but as with most of the terms in the domain of variability, the word selection has come to have more than one meaning. Facts have accumulated enormously since the time of Darwin, a more thorough knowledge has brought about distinctions, and divisions at a rapidly increasing rate, with which terminology has not kept pace. Selection includes all kinds of choice. Darwin distinguished between natural and artificial selection, but proper subdivisions of these conceptions are needed. In the fourth lecture we dealt with this same question, and saw that selection must, in the first place, make a choice between the elementary species of the same systematic form. This selection of species or species-selection was the work of Le Couteur and Patrick Shirreff, and is now in general use in practice where it has received the name of variety-testing. This clear and unequivocal term however, can hardly be included under the head of natural selection. The poetic terminology of selection by nature has already brought about many difficulties that should be avoided in the future. On the other hand, the designation of the process as a natural [744] selection of species complies as closely as possible with existing terminology, and does not seem liable to any misunderstanding. It is a selection between species. Opposed to it is the selection within the species. Manifestly the first should precede the second, and if this sequence is not conscientiously followed it will result in confusion. This is evident when it is considered that fluctuations can only appear with their pure and normal type in pure strains, and that each admixture of other units is liable to be shown by the form of the curves. More over, selection chooses single individuals, and a single plant, if it is not a hybrid, can scarcely pertain to two different species. The first choice therefore is apt to make the strain pure. In contrasting selection between species with that within the species, of course elementary species are meant, including varieties. The terms would be of no consequence if only rightly understood. For the sake of clearness we might designate the last named process with the term of intra-specific selection, and it is obvious that this term is applicable both to natural and to artificial selection. Having previously dealt with species-selection at sufficient length, we may now confine ourselves to the consideration of the intra-specific [745] selection process. In practice it is of secondary importance, and in nature it takes a very subordinate position. For this reason it will be best to confine further discussions to the experience of the breeders. Two different ways are open to make fluctuating variability profitable. Both consist in the multiplication of the chosen extremes, and this increase may be attained in a vegetative manner, or by the use of seeds. Asexual and sexual propagation are different in many respects, and so they are also in the domain of variability. In order to obtain a clear comprehension of this difference, it is necessary to start from the distinction between individual and partial fluctuations, as given in the last lecture. This distinction may be discussed more understandingly if the causes of the variability are taken into consideration. We have dealt with them at some length, and are now aware that inner conditions only, determine averages, while some fluctuation around them is allowable, as influenced by external conditions. These outward influences act throughout life. At the very first they impress their stamp on the whole organism, and incite a lasting change in distinct directions. This is the period of the development of the germ within the seed; it begins with the fusion of the sexual cells, and each of them may be influenced [746] to a noticeable degree before this union. This is the period of the determination of individual variability. As soon as ramifications begin, the external conditions act separately on every part, influencing some to a greater and others to a lesser degree. Here we have the beginning of partial variability. At the outset all parts may be affected in the same way and in the same measure, but the chances of such an agreement, of course, rapidly diminish. This is partly due to differences in exposure, but mainly to alterations of the sensibility of the organs themselves. It is difficult to gain a clear conception of the contrast between individual and partial variability, and neither is it easy to appreciate their cooperation rightly. Perhaps the best way is to consider their activity as a gradual narrowing of possibilities. At the outset the plant may develop its qualities in any measure, nothing being as yet fixed. Gradually however, the development takes a definite direction, for better or for worse. Is a direction once taken, then it becomes the average, around which the remaining possibilities are grouped. The plant or the organ goes on in this way, until finally it reaches maturity with one of the thousands of degrees of development, between which at the beginning it had a free choice. [747] Putting this discussion in other terms, we find every individual and every organ in the adult state corresponding with a single ordinate of the curve. The curve indicates the range of possibilities, the ordinate shows the choice that has been made. Now it is clear at once that this choice has not been made suddenly but gradually. Halfway of the development, the choice is halfway determined, but the other half is still undefined. The first half is the same for all the organs of the plant, and is therefore termed individual; the second differs in the separate members, and consequently is known as partial. Which of the two halves is the greater and which the lesser, of course depends on the cases considered. Finally we may describe a single example, the length of the capsules of the evening-primrose. This is highly variable, the longest reaching more than twice the length of the smallest. Many capsules are borne on the same spike, and they are easily seen to be of unequal size. They vary according to their position, the size diminishing in the main from the base upwards, especially on the higher parts. Likewise the fruits of weaker lateral branches are smaller. Curves are easily made by measuring a few hundred capsules from corresponding parts of different plants, or even by limiting the [748] inquiry to a single individual. These curves give the partial variability, and are found to comply with Quetelet's law. Besides this limited study, we may compare the numerous individuals of one locality or of a large plot of cultivated plants with one another. In doing so, we are struck with the fact that some plants have large and others small fruits. We now limit ourselves to the main spike of each plant, and perhaps to its lower parts, so as to avoid as far as possible the impression made by the partial fluctuations. The differences remain, and are sufficient to furnish an easy comparison with the general law. In order to do this, we take from each plant a definite number of capsules and measure their average length. In some experiments I took the twenty lowermost capsules of the main spikes. In this way one average was obtained for each plant, and combining these into a curve, it was found that these fluctuations also came under Quetelet's law. Thus the individual averages, and the fluctuations around each of them, follow the same rule. The first are a measure for the whole plant, the second only for its parts. As a general resume we can assert that, as a rule, a quality is determined in some degree during the earlier stages of the organism, and that this determination is valid throughout its [749] life. Afterwards only the minor points remain to be regulated. This makes it at once clear that the range of individual and partial variability together must be wider than that of either of them, taken alone. Partial fluctuations cannot, of course, be excluded. Thus our comparison is limited to individual and partial variability on one side, and partial fluctuations alone on the other side. Intra-specific selection is thus seen to fall under two heads: a selection between the individuals, and a choice within each of them. The first affords a wider and the latter a narrower field. Individual variability, considered as the result of outward influences operative during extreme youth, can be excluded in a very simple manner. Obviously it suffices to exclude extreme youth, in other words, to exclude the use of seeds. Multiplication in a vegetative way, by grafting and budding, by runners or roots, or by simple division of rootstocks and bulbs is the way in which to limit variability to the partial half. This is all we may hope to attain, but experience shows that it is a very efficient means of limitation. Partial fluctuations are generally far smaller than individual and partial fluctuations together. Individual variability in the vegetable kingdom [750] might be called seed-variation, as opposed to partial or bud-fluctuation. And perhaps these terms are more apt to convey a clear conception of the distinction than any other. The germ within the unripe seed is easily understood to be far more sensitive to external conditions than a bud. Multiplication of extremes by seed is thus always counteracted by individual variability, which at once reopens all, or nearly all, the initial possibilities. Multiplication by buds is exempt from this danger and thus leads to a high degree of uniformity. And this uniformity is in many cases exactly what the breeder endeavors to obtain. We will treat of this reopening of previous possibilities under the head of regression in the next lecture. It is not at all absolute, at least not in one generation. Part of the improvement remains, and favors the next generation. This part may be estimated approximately as being about one-third or one-half of the improvement attained. Hence the conclusion that vegetative multiplication gives rise to varieties which are as a rule twice or thrice as good as selected varieties of plants propagated by seeds. Hence, likewise the inference that breeders generally prefer vegetative multiplication of improved forms, and apply it in all possible cases. [751] Of course the application is limited, and forage crops and the greater number of vegetables will always necessarily be propagated by seed. Nature ordinarily prefers the sexual way. Asexual multiplications, although very common with perennial plants, appear not to offer important material for selection. Hence it follows that in comparing the work of nature with that of man, the results of selection followed by vegetative propagation should always be carefully excluded. Our large bulb-flowers and delicious fruits have nothing in common with natural products, and do not yield a standard by which to judge nature's work. It is very difficult for a botanist to give a survey of what practice has attained by the asexual multiplication of extremes. Nearly all of the large and more palatable fruits are due to such efforts. Some flowers and garden-plants afford further instances. By far the greatest majority of improved asexual varieties, however, are not the result of pure intra-specific selection. They are due largely to the choice of the best existing elementary species, and to some extent to crosses between them, or between distinct systematic species. In practice selection and hybridization go hand in hand and it is often difficult to ascertain what part of [752] the result is due to the one, and what to the other factor. The scientist, on the contrary, has nothing to do with the industrial product. His task is the analysis of the methods, in order to reach a clear appreciation of the influence of all the competing factors. This study of the working causes leads to a better understanding of the practical processes, and may become the basis of improvement in methods. Starting from these considerations, we will now give some illustrative examples, and for the first, choose one in which hybridization is almost completely excluded. Sugar-canes have long been considered to be plants without seed. Their numerous varieties are propagated only in a vegetative way. The stems are cut into pieces, each bearing one or two or more nodes with their buds. An entire variety, though it may be cultivated in large districts and even in various countries, behaves with respect to variability as a single individual. Its individual fluctuability has been limited to the earliest period of its life, when it arose from an unknown seed. The personal characters that have been stamped on this one seed, partly by its descent, and partly in the development of its germ during the period of ripening, have become the indelible characters [753] of the variety, and only the partial fluctuability, due to the effect of later influences, can now be studied statistically. This study has for its main object the production of sugar in the stems, and the curves, which indicate the percentage of this important substance in different stems of the same variety, comply with Quetelet's law. Each variety has its own average, and around this the data of the majority of the stems are densely crowded, while deviations on both sides are rare and become the rarer the wider they are. The "Cheribon" cane is the richest variety cultivated in Java, and has an average of 19% sugar, while it fluctuates between 11% and 28%. "Chunnic" averages 14%, "Black Manilla" 13% and "White Manilla" 10%; their highest and lowest extremes diverge in the same manner, being for the last named variety 1% and 15%. This partial variability is of high practical interest, because on it a selection may be founded. According to the conceptions described in a previous lecture, fluctuating variability is the result of those outward factors that determine the strength of development of the plant or the organ. The inconstancy of the degree of sensibility, combined with the ever-varying weather conditions preclude any close proportionality, but apart from this difficulty there is, in the [754] main, a distinct relation between organic strength and the development of single qualities. This correlation has not escaped observation in the case of the sugar-cane, and it is known that the best grown stocks are generally the richest in sugar. Now it is evident that the best grown and richest stems will have the greater chance of transmitting these qualities to the lateral-buds. This at once gives, a basis for vegetative selection, upon which it is not necessary to choose a small number of very excellent stems, but simply to avoid the planting of all those that are below the average. By this means the yield of the cultures has often noticeably been enhanced. As far as experience goes, this sort of selection, however profitable, does not conduce to the production of improved races. Only temporary ameliorations are obtained, and the selection must be made in the same manner every year. Moreover the improvement is very limited and does not give any promise of further increase. In order to reach this, one has to recur to the individual fluctuability, and therefore to seed. Nearly half a century ago, Parris discovered, on the island of Barbados, that seeds might occasionally be gathered from the canes. These, however, yielded only grass-like plants of no real value. The same observation was made [755] shortly afterwards in Java and in other sugar producing countries. In the year 1885, Soltwedel, the director of one of the experiment stations for the culture of sugar-cane in Java, conceived the idea of making use of seedlings for the production of improved races. This idea is a very practical one, precisely because of the possibility of vegetative propagation. If individuals would show the same range as that of partial fluctuability, then the choice of the extremes would at once bring the average up to the richness of the best stocks. Once attained, this average would be fixed, without further efforts. Unfortunately there is one great drawback. This is the infertility of the best variety, that of the "Cheribon" cane. It flowers abundantly in some years, but it has never been known to produce ripe seeds. For this reason Soltwedel had to start from the second best sort, and chose the "Hawaii" cane. This variety usually yields about 14% sugar, and Soltwedel found among his seedlings one that showed 15%. This fact was quite unexpected at that time, and excited widespread interest in the new method, and since then it has been applied to numerous varieties, and many thousands of seedlings have been raised and tested as to their sugar-production. [756] From a scientific point of view the results are quite striking. From the practical standpoint, however, the question is, whether the "Hawaii" and other fertile varieties are adequate to yield seedlings, which will surpass the infertile "Cheribon" cane. Now "Hawaii" averages 14% and "Cheribon" 19%, and it is easily understood that a "Hawaii" seedling with more than 19% can be expected only from very large sowings. Hundreds of thousands of seedlings must be cultivated, and their juice tested, before this improvement can be reached. Even then, it may have no significance for practical purposes. Next to the amount of sugar comes the resistance to the disease called "Sereh," and the new race requires to be ameliorated in this important direction, too. Other qualities must also be considered, and any casual deterioration in other characters would make all progress illusory. For these reasons much time is required to attain distinct improvements. These great difficulties in the way of selecting extremes for vegetative propagation are of course met with everywhere. They impede the work of the breeder to such a degree, that but few men are able to surmount them. Breeding new varieties necessitates the bending of every effort to this purpose, and a clear conception of [757] the manifold aspects of this intricate problem. These fall under two heads, the exigencies of practice, and the physiologic laws of variability. Of course, only the latter heading comes within the limits of our discussion which includes two main points. First comes the general law of fluctuation that, though slight deviations from the average may be found by thousands, or rather in nearly every individual, larger and therefore important deviations are very rare. Thousands of seedlings must be examined carefully in order to find one or two from which it might be profitable to start a new race. This point is the same for practical and for scientific investigation. In the second place however, a digression is met with. The practical man must take into consideration all the varying qualities of his improved strains. Some of them must be increased and others be decreased, and their common dependency on external conditions often makes it very difficult to discover the desired combinations. It is obvious, however, that the neglect of one quality may make all improvement of other characters wholly useless. No augmentation of sugar-percentage, of size and flavor of fruits can counterbalance an increase in sensitiveness to disease, and so it is with other qualities also. [758] Improved races for scientific investigation can be kept free from infection, and protected against numerous other injuries. In the experimental garden they may find conditions which cannot be realized elsewhere. They may show a luxuriant growth, and prove to be excellent material for research, but have features which, having been overlooked at the period of selection, would at once condemn them if left to ordinary conditions, or to the competition of other species. Considering all these obstacles, it is only natural that breeders should use every means to reach their goal. Only in very rare instances do they follow methods analogous to scientific processes, which tend to simplify the questions as much as possible. As a rule, the practical way is the combination of as many causes of variability as possible. Now the three great sources of variability are, as has been pointed out on several occasions, the original multiformity of the species, fluctuating variability, and hybridization. Hence, in practical experiments, all three are combined. Together they yield results of the highest value, and Burbank's improved fruits and flowers give testimony to the practical significance of this combination. From a scientific point of view however, it is [759] ordinarily difficult, if not impossible, to discern the part which each of the three great branches of variability has taken in the origination of the product. A full analysis is rarely possible, and the treatment of one of the three factors must necessarily remain incomplete. Notwithstanding these considerations, I will now give some examples in order to show that fluctuating variability plays a prominent part in these improvements. Of course it is the third in importance in the series. First comes the choice of the material from the assemblage of species, elementary species and varieties. Hybridization comes next in importance. But even the hybrids of the best parents may be improved, because they are no less subject to Quetelet's law than any other strain. Any large number of hybrids of the same ancestry will prove this, and often the excellency of a hybrid variety depends chiefly, or at least definitely, on the selection of the best individuals. Being propagated only in a vegetative way, they retain their original good qualities through all further culture and multiplication. As an illustrative example I will take the genus _Canna_. Originally cultivated for its large and bright foliage only, it has since become a flowering plant of value. Our garden strains have originated by the crossing of [760] a number of introduced wild species, among which the _Canna indica_ is the oldest, now giving its name to the whole group. It has tall stems and spikes with rather inconspicuous flowers with narrow petals. It has been crossed with _C. nepalensis_ and _C. warczewiczii_, and the available historic evidence points to the year 1846 as that of the first cross. This was made by Annee between the _indica_ and the _nepalensis_; it took ten years to multiply them to the required degree for introduction into commerce. These first hybrids had bright foliage and were tall plants, but their flowers were by no means remarkable. Once begun, hybridization was widely practiced. About the year 1889 Crozy exhibited at Paris the first beautifully flowering form, which he named for his wife, "Madame Crozy." Since that time he and many others, have improved the flowers in the shape and size, as well as in color and its patterns. In the main, these ameliorations have been due to the discovery and introduction of new wild species possessing the required characters. This is illustrated by the following incident. In the year 1892 I visited Mr. Crozy at Lyons. He showed me his nursery and numerous acquisitions, those of former years as well as those that were quite new, and which were in the process of rapid [761] multiplication, previous to being given to the trade. I wondered, and asked, why no pure white variety was present. His answer was "Because no white species had been found up to the present time, and there is no other means of producing white varieties than by crossing the existing forms with a new white type." Comparing the varieties produced in successive periods, it is very easy to appreciate their gradual improvement. On most points this is not readily put into words, but the size of the petals can be measured, and the figures may convey at least some idea of the real state of things. Leaving aside the types with small flowers and cultivated exclusively for their foliage, the oldest flowers of _Canna_ had petals of 45 mm. length and 13 mm. breadth. The ordinary types at the time of my visit had reached 61 by 21 mm., and the "Madame Crozy" showed 66 by 30 mm. It had however, already been surpassed by a few commercial varieties, which had the same length but a breadth of 35 mm. And the latest production, which required some years of propagation before being put on the market, measured 83 by 43 mm. Thus in the lapse of some thirty years the length had been doubled and the breadth tripled, giving flowers with broad corollas and with petals [762] joined all around, resembling the best types of lilies and _Amaryllis_. Striking as this result unquestionably is, it remains doubtful as to what part of it is due to the discovery and introduction of new large flowered species, and what to the selection of the extremes of fluctuating variability. As far as I have been able to ascertain however, and according to the evidence given to me by Mr. Crozy, selection has had the largest part in regard to the size, while the color-patterns are introduced qualities. The scientific analysis of other intricate examples is still more difficult. To the practical breeder they often seem very simple, but the student of heredity, who wishes to discern the different factors, is often quite puzzled by this apparent simplicity. So it is in the case of the double lilacs, a large number of varieties of which have recently been originated and introduced into commerce by Lemoine of Nancy. In the main they owe their origin to the crossing and recrossing of a single plant of the old double variety with the numerous existing single-flowered sorts. This double variety seems to be as old as the culture of the lilacs. It was already known to Munting, who described it in the year 1671. Two centuries afterwards, in 1870, a new description [763] was given by Morren, and though more than one varietal name is recorded in his paper, it appears from the facts given that even at that time only one variety existed. It was commonly called _Syringa vulgaris azurea plena_, and seems to have been very rare and without real ornamental value. Lemoine, however, conceived the desirability of a combination of the doubling with the bright colors and large flower-racemes of other lilacs, and performed a series of crosses. The "_azurea plena_" has no stamens, and therefore must be used in all crosses as the pistil-parent; its ovary is narrowly inclosed in the tube of the flower, and difficult to fertilize. On the other hand, new crosses could be made every year, and the total number of hybrids with different pollen-parents was rapidly increased. After five years the hybrids began to flower and could be used for new crosses, yielding a series of compound hybrids, which however, were not kept separate from the products of the first crosses. Gradually the number of the flowering specimens increased, and the character of doubling was observed to be variable to a high degree. Sometimes only one supernumerary petal was produced, sometimes a whole new typical corolla was extruded from within the first. In the same [764] way the color and the number of the flowers on each raceme were seen to vary. Thousands of hybrids were produced, and only those which exhibited real advantages were selected for trade. These were multiplied by grafting, and each variety at present consists only of the buds of one original individual and their products. No constancy from seed is assumed, many varieties are even quite sterile. Of course, no description was given of the rejected forms. It is only stated that many of them bore either single or poorly filled flowers, or were objectionable in some other way. The range of variability, from which the choices were made, is obscure and only the fact of the selection is prominent. What part is due to the combination of the parental features and what to the individual fluctuation of the hybrid itself cannot be ascertained. So it is in numerous other instances. The dahlias have been derived from three or more original species, and been subjected to cultivation and hybridization in an ever-increasing scale for a century. The best varieties are only propagated in the vegetative way, by the roots and buds, or by grafting and cutting. Each of them is, with regard to its hereditary qualities, only one individual, and the individual characters were selected at the same time with the [765] varietal and hybrid characters. Most of them are very inconstant from seed and as a rule, only mixtures are offered for sale in seed-lists. Which of their ornamental features are due to fluctuating deviation from an average is of course unknown. _Amaryllis_ and _Gladiolus_ are surrounded with the same scientific uncertainties. Eight or ten, or even more, species have been combined into one large and multiform strain, each bringing its peculiar qualities into the mixed mass. Every hybrid variety is one individual, being propagated by bulbs only. Colors and color-patterns, shape of petals and other marks, have been derived from the wild ancestors, but the large size of many of the best varieties is probably due to the selection of the extremes of fluctuating variability. So it is with the begonias of our gardens, which are also composite hybrids, but are usually sown on a very large scale. Flowers of 15 cm. diameter are very showy, but there can be no doubt about the manner in which they are produced, as the wild species fall far short of this size. Among vegetables the potatoes afford another instance. Originally quite a number of good species were in culture, most of them having small tubers. Our present varieties are due to hybridization and selection, each of them being propagated only in the vegetative way. [766] Selection is founded upon different qualities, according to the use to be made of the new sort. Potatoes for the factory have even been selected for their amount of starch, and in this case at least, fluctuating variability has played a very important part in the improvement of the race. Vegetative propagation has the great advantage of exempting the varieties from regression to mediocrity, which always follows multiplication by seeds. It affords the possibility of keeping the extremes constant, and this is not its only advantage. Another, likewise highly interesting, side of the question is the uniformity of the whole strain. This is especially important in the case of fruits, though ordinarily it is regarded as a matter of course, but there are some exceptions which give proof of the real importance of the usual condition. For example, the walnut-tree. Thousands of acres of walnut-orchards consist of seedling trees grown from nuts of unknown parentage. The result is a great diversity in the types of trees and in the size and shape of the nuts, and this diversity is an obvious disadvantage to the industry. The cause lies in the enormous difficulties attached to grafting or budding of these trees, which make this method very expensive and to a high degree uncertain and unsatisfactory. [767] After this hasty survey of the more reliable facts of the practice of an asexual multiplication of the extremes of fluctuating variability, we may now return to the previously mentioned theoretical considerations. These are concerned with an estimation of the chances of the occurrence of deviations, large enough to exhibit commercial value. This chance may be calculated on the basis of Quetelet's law, whenever the agreement of the fluctuation of the quality under consideration has been empirically determined. In the discussion of the methods of comparing two curves, we have pointed to the quartiles as the decisive points, and to the necessity of drawing the curves so that these points are made to overlie one another, on each side of the average. If now we calculate the binomium of Newton for different values of the exponent, the sum of the coefficients is doubled for each higher unit of the exponent, and at the same time the extreme limit of the curve is extended one step farther. Hence it is possible to calculate a relation between the value of the extreme and the number of cases required. It would take us too long to give this calculation in detail, but it is easily seen that for each succeeding step the number of individuals must be doubled, though the length of the steps, or the amount of increase of the quality [768] remains the same. The result is that many thousands of seedlings are required to go beyond the ordinary range of variations, and that every further improvement requires the doubling of the whole culture. If ten thousand do not give a profitable deviation, the next step requires twenty thousand, the following forty thousand, and so on. And all this work would be necessary for the improvement of a single quality, while practice requires the examination and amelioration of nearly all the variable characters of the strain. Hence the rule that great results can only be obtained by the use of large numbers, but it is of no avail to state this conclusion from a scientific point of view. Scientific experimenters will rarely be able to sacrifice fifty thousand plants to a single selection. The problem is to introduce the principle into practice and to prove its direct usefulness and reliability. It is to Luther Burbank that we owe this great achievement. His principles are in full harmony with the teachings of science. His methods are hybridization and selection in the broadest sense and on the largest scale. One very illustrative example of his methods must suffice to convey an idea of the work necessary to produce a new race of superlative excellency. Forty thousand blackberry and raspberry [769] hybrids were produced and grown until the fruit matured. Then from the whole lot a single variety was chosen as the best. It is now known under the name of "Paradox." All others were uprooted with their crop of ripening berries, heaped up into a pile twelve feet wide, fourteen feet high and twenty-two feet long, and burned. Nothing remained of that expensive and lengthy experiment, except the one parent-plant of the new variety. Similar selections and similar amount of work have produced the famous plums, the brambles and the blackberries, the Shasta daisy, the peach almond, the improved blueberries, the hybrid lilies, and the many other valuable fruits and garden-flowers that have made the fame of Burbank and the glory of horticultural California. [770] LECTURE XXVII INCONSTANCY OF IMPROVED RACES The greater advantages of the asexual multiplication of extremes are of course restricted to perennial and woody plants. Annual and biennial species cannot as a rule, be propagated in this way, and even with some perennials horticulturists prefer the sale of seeds to that of roots and bulbs. In all these cases it is clear that the exclusion of the individual variability, which was shown to be an important point in the last lecture, must be sacrificed. Seed-propagation is subject to individual as well as to fluctuating variability. The first could perhaps be designated by another term, embryonic variability, since it indicates the fluctuations occurring during the period of development of the germ. This period begins with the fusion of the male and female elements and is largely dependent upon the vigor of these cells at the moment, and on the varying qualities they may have acquired. It comprises in the main the time of the ripening of the seed, and [771] might perhaps best be considered to end with the beginning of the resting stage of the ripe seed. Hence it is clear that the variability of seed-propagated annual races has a wider range than that of perennials, shrubs and trees. At present it is difficult to discern exactly the part each of these two main factors plays in the process. Many indications are found however, that make it probable that embryonic variability is wider, and perhaps of far greater importance than the subsequent partial fluctuations. The high degree of similarity between the single specimens of a vegetative variety, and the large amount of variability in seed-races strongly supports this view. The propagation and multiplication of the extremes of fluctuating variability by means of seeds requires a close consideration of the relation between seedling and parent. The easiest way to get a clear conception of this relation is to make use of the ideas concerning the dependency of variability upon nourishment. Assuming these to be correct in the main, and leaving aside all minor questions, we may conclude that the chosen extreme individual is one of the best nourished and intrinsically most vigorous of the whole culture. On account of these very qualities it is capable of nourishing all of its organs better and also its seeds. In other words, the seeds [772] of the extreme individuals have exceptional chances of becoming better nourished than the average of the seeds of the race. Applying the same rule to them, it is easily understood that they will vary, by reason of this better nourishment, in a direction corresponding to that of their parent. This discussion gives a very simple explanation of the acknowledged fact that the seeds of the extremes are in the main the best for the propagation of the race. It does not include however, all the causes for this preferment. Some are of older date and due to previous influences. A second point in our discussion is the appreciation of the fact that a single individual may be chosen to gather the seed from, and that these seeds, and the young plants they yield, are as a rule, numerous. Hence it follows that we are to compare their average and their extremes with the qualities of the parents. Both are of practical as well as of theoretical interest. The average of the progeny is to be considered as the chief result of the selection in the previous generation, while the extremes, at least those which depart in the same direction, are obviously the means of further improvement of the race. Thus our discussion should be divided into [773] two heads. One of these comprises the relation of the average of the progeny to the exceptional qualities of the chosen parent, and the other the relation of exceptional offspring to the exceptional parents. Let us consider the averages first. Are they to be expected to be equal to the unique quality of the parent, or perhaps to be the same as the average of the whole unselected race? Neither of these cases occur. Experience is clear and definite on this important point. Vilmorin, when making the first selections to improve the amount of sugar in beets, was struck with the fact that the average of the progeny lies between that of the original strain and the quality of the chosen parent. He expressed his observation by stating that the progeny are grouped around and diverge in all directions from some point, placed on the line which unites their parent with the type from which it sprang. All breeders agree on this point, and in scientific experiments it has often been confirmed. We shall take up some illustrative examples presently, but in order to make them clear, it is necessary to give a closer consideration to the results of Vilmorin. From his experience it follows that the average of the progeny is higher than that of the race at large, but lower than the chosen parent. [774] In other words, there is a progression and a regression. A progression in relation to the whole race, and a regression in comparison with the parent. The significance of this becomes clear at once, if we recall the constancy of the variety which could be obtained from the selected extreme in the case of vegetative multiplication. The progression is what the breeder wants, the regression what he detests. Regression is the permanency of part of the mediocrity which the selection was invoked to overcome. Manifestly it is of the highest interest that the progression should be as large, and the regression as small as possible. In order to attain this goal the first question is to know the exact measure of progression and regression as they are exhibiting themselves in the given cases, and the second is to inquire into the influences, on which this proportion may be incumbent. At present our notions concerning the first point are still very limited and those concerning the second extremely vague. Statistical inquiries have led to some definite ideas about the importance of regression, and these furnish a basis for experimental researches concerning the causes of the phenomenon. Very advantageous material for the study of progression and regression in the realm of fluctuating variability is afforded by the [775] ears of corn or maize. The kernels are arranged in longitudinal rows, and these rows are observed to occur in varying, but always even, numbers. This latter circumstance is due to the fact that each two neighboring rows contain the lateral branches of a single row of spikelets, the ages of which however, are included in the fleshy body of the ear. The variation of the number of the rows is easily seen to comply with Quetelet's law, and often 30 or 40 ears suffice to give a trustworthy curve. Fritz Muller made some experiments upon the inheritance of the number of the rows, in Brazil. He chose a race which averaged 12 rows, selected ears with 14, 16 and 18 rows, etc., and sowed their kernels separately. In each of-these cultures he counted the rows of the seeds on the ears of all the plants when ripe, and calculated their average. This average, of course, does not necessarily correspond to a whole number, and fractions should not be neglected. According to Vilmorin's rule he always found some progression of the average and some regression. Both were the larger, the more the parent-ear differed from the general average, but the proportion between both remained the same, and seems independent of the amount of the deviation. Putting the deviation at 5, the progression calculated from his figures is [776] 2 and the regression 3. In other words the average of the progeny has gained over the average of the original variety slightly more than one-third, and slightly less than one-half of the parental deviation. I have repeated this experiment of Fritz Miller's and obtained nearly the same regression of three-fifths, though working with another variety, and under widely different climatic conditions. The figures of Fritz Muller were, as given below, in one experiment. In the last column I put the improvement calculated for a proportion of two-fifths above the initial average of 12. Rows on Average of rows 12 + 2/5 of parent ears of progeny Difference 14 12.6 12.8 16 14.1 13.6 18 15.2 14.4 20 15.8 15.2 22 16.1 16.0 Galton, in his work on natural inheritance, describes an experiment with the seeds of the sweet pea or _Lathyrus odoratus_. He determined the average size in a lot of purchased seeds, and selected groups of seeds of different, but for each group constant, sizes. These were sown, and the average of the seeds was determined anew in the subsequent harvest they yielded. These figures agreed with the rule of Vilmorin and were calculated in the manner [777] given for the test of the corn. The progression and regression were found to be proportionate to the amount of the deviation. The progression of the average was one-third, and the regression in consequence two-thirds of the total deviation. The amelioration is thus seen to be nearly, though not exactly, the same as in the previous case. From the evidence of the other corresponding experiments, and from various statistical inquiries it seems that the value of the progression is nearly the same in most cases, irrespective of the species used and the quality considered. It may be said to be from one-third to one-half of the parental deviation, and in this form the statement is obviously of wide and easy applicability. Our figures also demonstrate the great preeminence of vegetative varieties above the improved strains multiplied by seeds. They have a definite relation. Asexually multiplied strains may be said to be generally two times or even three times superior to the common offspring. This is a difference of great practical importance, and should never be lost sight of in theoretical considerations of the productive capacity of selection. Multiplication by seed however, has one great advantage over the asexual method; it may be repeated. The [778] selection is not limited to a single choice, but may be applied in two or more succeeding generations. Obviously such a repetition affords a better chance of increasing the progression of the average and of ameliorating the race to a greater degree than would be possible by a single choice. This principle of repeated selection is at present the prominent feature of race improvement. Next to variety-testing and hybridizing it is the great source of the steady progression of agricultural crops. From a practical standpoint the method is clear and as perfect as might be expected, but this is not the side of the problem with which we are concerned here. The theoretical analysis and explanation of the results obtained, however, is subject to much doubt, and to a great divergence of conceptions. So it is also with the application of the practical processes to those occurring in nature. Some assume that here repeated selection is only of subordinate importance, while others declare that the whole process of evolution is due to this agency. This very important point however, will be reserved for the next lecture, and only the facts available at present will be considered here. As a first example we may take the ray-florets of the composites. On a former occasion we have dealt with their fluctuation in number and [779] found that it is highly variable and complies in the main with Quetelet's law. _Madia elegans_, a garden species, has on the average 21 rays on each head, fluctuating between 16 and 25 or more. I saved the seeds of a plant with only 17 rays on the terminal head, and got from them a culture which averaged 19 rays, which is the mean between 21 and 17. In this second generation I observed the extremes to be 22 and 12, and selected a plant with 13 rays as the parent for a continuation of the experiment. The plants, which I got from its seeds, averaged 18 and showed 22 and 13 as extremes. The total progression of the average was thus, in two generations, from 21 to 18, and the total regression from 13 to 18, and the proportion is thus seen to diminish by the repetition rather than to increase. This experiment, however, is of course too imperfect upon which to found general conclusions. It only proves the important fact that the improved average of the second generation is not the starting-point for the further improvement. But the second generation allows a choice of an extreme, which diverges noticeably more from the mean than any individual of the first culture, and thereby gives a larger amount of absolute progression, even if the proportion between progression and regression remains [780] the same. The repetition is only an easy method of getting more widely deviating extremes; whether it has, besides this, another effect, remains doubtful. In order to be able to decide this question, it is necessary to repeat the selection during a series of generations. In this way the individual faults may be removed as far as possible. I chose an experiment of Fritz Muller, relating to the number of rows of grains on the ears exactly as in the case above referred to, and which I have repeated in my experimental garden at Amsterdam. I started from a variety known to fructify fairly regularly in our climate, and exhibiting in the mean 12-14 rows, but varying between 8 and 20 as exceptional cases. I chose an ear with 16 rows and sowed its seeds in 1887. A number of plants were obtained, from each of which, one ear was chosen in order to count its rows. An average of 15 rows was found with variations complying with Quetelet's law. One ear reached 22 rows, but had not been fertilized, some others had 20 rows, and the best of these was chosen for the continuation of the experiment. I repeated the sowing during 6 subsequent generations in the same way, choosing each time the most beautiful ear from among those with the greatest number of rows. Unfortunately with the increase of the number the [781] size of the grains decreases, the total amount of nourishment available for all of them remaining about the same. Thus the kernels and consequently the new plants became smaller and weaker, and the chance of fertilization was diminished in the ears with the highest number of rows. Consequently the choice was limited, and after having twice chosen a spike with 20 and once one with 24 rows, I finally preferred those with the intermediate number of 22. This repeated choice has brought the average of my race up from 13 to 20, and thus to the extreme limit of the original variety. Seven years were required to attain this result, or on an average the progression was one row in a year. This augmentation was accompanied by an accompanying movement of the whole group in the same direction. The extreme on the side of the small numbers came up from 8 to 12 rows, and cobs with 8 or 10 rows did not appear in my race later than the third generation. On the other side the extreme reached 28, a figure never reached by the original variety as cultivated with us, and ears with 24 and 26 rows have been seen during the four last generations in increasing numbers. This slow and gradual amelioration was partly due to the mode of pollination of the corn. [782] The pollen falls from the male spikes on the ears of the same plant, but also is easily blown on surrounding spikes. In order to get the required amount of seed it is necessary in our climate to encroach as little as possible upon free pollination, aiding the self-pollination, but taking no precautions against intercrossing. It is assumed that the choice of the best ears indicates the plants which have had the best pollen-parents as well as the best pistil parents, and that selection here, as in other cases, corrects the faults of free intercrossing. But it is granted that this correction is only a slow one, and accounts in a great degree for the slowness of the progression. Under better climatic conditions and with a more entire isolation of the individuals, it seems very probable that the same result could have been reached in fewer generations. However this may be, the fact is that by repeated selection the strain can be ameliorated to a greater extent than by a single choice. This result completely agrees with the general experience of breeders and the example given is only an instance of a universal rule. It has the advantage of being capable of being recorded in a numerical way, and of allowing a detailed and definite description of all the succeeding generations. The entire harvest of all [783] of them has been counted and the figures combined into curves, which at once show the whole course of the pedigree-experiment. These curves have in the main taken the same shape, and have only gradually been moved in the chosen direction. Three points are now to be considered in connection with this experiment. The first is the size of the cultures required for the resulting amelioration. In other words, would it have been possible to attain an average of 20 rows in a single experiment? This is a matter of calculation, and the calculation must be based upon the experience related above, that the progression in the case of maize is equal to two-fifths of the parental deviation. A cob with 20 rows means a deviation of 7 from the average of 13, the incipient value of my race. To reach such an average at once, an ear would be required with 7 x 5/2 = 17-1/2 rows above the average, or an ear with 30-32 rows. These never occur, but the rule given in a previous lecture gives a method of calculating the probability of their occurrence, or in other words, the number of ears required to give a chance of finding such an ear. It would take too long to give this calculation here, but I find that approximately 12,000 ears would be required to give one with 28 rows, which was the highest number attained in [784] my experiment, while 100,000 ears would afford a chance of one with 32 rows*. Had I been able to secure and inspect this number of ears, perhaps I would have needed only a year to get an average of 20 rows. This however, not being the case, I have worked for seven years, but on the other hand have cultivated all in all only about one thousand individuals for the entire experiment. Obviously this reduction of the size of the experiment is of importance. One hundred thousand ears of corn could of course, be secured directly from trade or from some industrial culture, but corn is cultivated only to a small extent in Holland, and in most cases the requisite number of individuals would be larger than that afforded by any single plantation. Repeated selection is thereby seen to be the means of reducing the size of the required cultures to possible measures, not only in the experimental-garden, but also for industrial purposes. A selection from among 60,000-100,000 individuals may be within reach of Burbank, but of few others. As a rule they prefer a longer time with a smaller lot of plants. This * On about 200 ears the variability ranges from 8-22 rows, and this leads approximately to one row more by each doubling of the numbers of instances. One ear with 22 rows in 200 would thus lead to the expectation of one ear with 32 rows in 100,000 ears. [785] is exactly what is gained by repeated selections. To my mind this reduction of the size of the cultures is probably the sole effect of the repetition. But experience is lacking on this point, and exact comparisons should be made whenever possible, between the descendants of a unique but extreme choice, and a repeated but smaller selection. The effect of the repetition on the nourishment of the chosen representatives should be studied, for it is clear that a plant with 22 rows, the parents and grandparents of which had the same number, indicates a better condition of internal qualities than one with the same number of rows, produced accidentally from the common race. In this way it may perhaps be possible to explain, why in my experiment an ear with 22 rows gave an average offspring with 20, while the calculation, founded on the regression alone would require a parental ear with 32 rows. However, as already stated, this discussion is only intended to convey some general idea as to the reduction of the cultures by means of repeated selections, as the material at hand is wholly inadequate for any closer calculation. This important point of the reduction may be illustrated in still another manner. The sowing of very large numbers is only required because it is impossible to tell from the [786] inspection of the seeds which of them will yield the desired individual. But what is impossible in the inspection of the seeds may be feasible, at least in important measure, in the inspection of the plants which bear the seeds. Whenever such an inspection demonstrates differences, in manifest connection with the quality under consideration, any one will readily grant that it would be useless to sow the seeds of the worst plants, and that even the whole average might be thrown over, if it were only possible to point out a number of the best. But it is clear that by this inspection of the parent plants the principle of repeated selection is introduced for two succeeding generations, and that its application to a larger series of generations is only a question of secondary importance. Summing up our discussion of this first point we may assert that repeated selection is only selection on a small and practical scale, while a single choice would require numbers of individuals higher than are ordinarily available. A second discussion in connection with our pedigree-culture of corn is the question whether the amelioration obtained was of a durable nature, or only temporary. In other words, whether the progeny of the race would remain constant, if cultivated after cessation of the selection. In order to ascertain this, [787] I continued the culture during several generations, choosing ears with less than the average number of rows. The excellence of the race at once disappeared, and the ordinary average of the variety from which I had started seven years before, returned within two or three seasons. This shows that the attained improvement is neither fixed nor assured and is dependent on continued selection. This result only confirms the universal experience of breeders, which teaches the general dependency of improved races on continued selection. Here a striking contrast with elementary species or true varieties is obvious. The strains which nature affords are true to their type; their average condition remains the same during all the succeeding generations, and even if it should be slightly altered by changes in the external conditions, it returns to the type, as soon as these changes come to an end. It is a real average, being the sum of the contribution of all the members of the strain. Improved races have only an apparent average, which is in fact biased by the exclusion of whole groups of individuals. If left to themselves, their appearance changes, and the real average soon returns. This is the common experience of breeders. A third point is to be discussed in connection [788] with the detailed pedigree-cultures. It is the question as to what might be expected from a continuation of improvement selection. Would it be possible to obtain any imaginable deviation from the original type, and to reach independency from further selection? This point has not until now attracted any practical interest, and from a practical point of view and within the limits of ordinary cultures, it seems impossible to obtain a positive answer. But in the theoretical discussion of the problems of descent it has become of the highest importance, and therefore requires a separate treatment, which will be reserved for the next lecture. Here we come upon another equally difficult problem. It relates to the proportion of embryonic or individual fluctuation, to partial variation as involved in the process of selection. Probably all qualities which may be subjected to selection vary according to both principles, the embryonic decision giving only a more definite average, around which the parts of the individual are still allowed to oscillate. It is so with the corn, and whenever two or more ears are ripening or even only flowering on the same plant, differences of a partial nature may be seen in the number of their rows. These fluctuations are only small however, ordinarily not exceeding two and rarely four [789] rows. Choosing always the principal ear, the figures may be taken to indicate the degree of personal deviation from the average of the race. But whenever we make a mistake, and perchance sow from an ear, the deviation of which was largely due to partial variation, the regression should be expected to become considerably larger. Hence it must be conceded that exact calculations of the phenomena of inheritance are subject to much uncertainty, resulting from our very imperfect knowledge concerning the real proportion of the contributing factors, and the difficulty of ascertaining their influence in any given case. Here also we encounter more doubts than real facts, and much remains to be done before exact calculations may become of real scientific value. Returning to the question of the effects of selection in the long run, two essentially different cases are to be considered. Extremes may be selected from among the variants of ordinary fluctuating variability, or from ever-sporting varieties. These last we have shown to be double races. Their peculiar and wide range of variability is due to the substitution of two characters, which exclude one another, or if combined, are diminished in various degrees. Striped flowers and stocks, "five-leaved" clover, pistilloid opium-poppies and numerous other [790] monstrosities have been dealt with as instances of such ever-sporting varieties. Now the question may be put, what would be the effect of selection if in long series of years one of the two characters of such a double race were preferred continuously, to the complete exclusion of the other. Would the race become changed thereby? Could it be affected to such a degree as to gradually lose the inactive quality, and cease to be a double race? Here manifestly we have a means by which to determine what selection is able to accomplish. Physiologic experiments may be said to be too short to give any definite evidence. But cases may be cited where nature has selected during long centuries and with absolute constancy in her choice. Moreover unconscious selections by man have often worked in an analogous manner, and many cultivated plants may be put to the test concerning the evidence they might give on this point. Stating beforehand the result of this inquiry, we may assert that long-continued selection has absolutely no appreciable effect. Of course I do not deny the splendid results of selection during the first few years, nor the necessity of continued selection to keep the improved races to the height of their ameliorated qualities. I only wish to state that the work [791] of selection here finds its limit and that centuries and perhaps geologic periods of continued effort in the same direction are not capable of adding anything more to the initial effect. Some illustrative examples may suffice to prove the validity of this assertion. Every botanist who has studied the agricultural practice of plant-breeding, or the causes of the geographic distribution of plants, will easily recall to his mind numerous similar cases. Perhaps the most striking instance is afforded by cultivated biennial plants. The most important of them are forage-beets and sugar-beets. They are, of course, cultivated only as biennials, but some annual specimens may be seen each year and in nearly every field. They arise from the same seed as the normal individuals, and their number is obviously dependent on external conditions, and especially on the time of sowing. Ordinary cultures often show as much as 1% of these useless plants, but the exigencies of time and available labor often compel the cultivator to have a large part of his fields sown before spring. In central Europe, where the climate is unfavorable at this season, the beets respond by the production of far larger proportions of annual specimens, their number coming often up to 20% or more, thus constituting noticeable losses in the product [792] of the whole field. Rimpau, who has made a thorough study of this evil and has shown its dependency on various external conditions, has also tried to find methods of selection with the aim of overcoming it, or at least of reducing it to uninjurious proportions. But in these efforts he has reached no practical result. The annuals are simply inexterminable. Coming to the alternative side of the problem it is clear that annuals have always been excluded in the selection. Their seeds cannot be mixed with the good harvest, not even accidentally, since they have ripened in a previous year. In order to bear seeds in the second year beets must be taken from the field, and kept free from frost through the winter. The following spring they are planted out, and it is obvious that even the most careless farmer is not liable to mix them with annual specimens. Hence we may conclude that a strict and unexcelled process of selection has been applied to the destruction of this tendency, not only for sugar-beets, since Vilmorin's time, when selection had become a well understood process, but also for forage-beets since the beginning of beet culture. Although unconscious, the selection of biennials must have been uninterrupted and strict throughout many centuries. It has had no effect at all. Annuals are seen [793] to return every year. They are ineradicable. Every individual is in the possession of this latent quality and liable to convert it into activity as soon as the circumstances provoke its appearance, as proved by the increase of annuals in the early sowings. Hence the conclusion that selection in the long run is not adequate to deliver plants from injurious qualities. Other proofs could be given by other biennials, and among them the stray annual plants of common carrots are perhaps the most notorious. In my own cultures of evening-primroses I have preferred the annuals and excluded the biennials, but without being able to produce a pure annual race. As soon as circumstances are favorable, the biennials return in large numbers. Cereals give analogous proofs. Summer and winter varieties have been cultivated separately for centuries, but in trials it is often easy to convert the one into the other. No real and definite isolation has resulted from the effect of the long continued unconscious selection. Striped flowers, striped fruits, and especially striped radishes afford further examples. It would be quite superfluous to dwell upon them. Selection always tends to exclude the monochromatic specimens, but does not prevent their return in every generation. Numerous [794] rare monstrosities are in the same category, especially when they are of so rare occurrence as not to give any noticeable contribution to the seed-production, or even if they render their bearers incapable of reproduction. In such cases the selection of normal plants is very severe or even absolute, but the anomalies are by no means exterminated. Any favorable circumstances, or experimental selection in their behalf shows them to be still capable of full development. Numerous cases of such subordinate hereditary characters constitute the greater part of the science of vegetable teratology. If it should be objected that all these cases cover too short a time to be decisive, or at least fail in giving evidence relative to former times, alpine plants afford a proof which one can hardly expect to be surpassed. During the whole present geologic epoch they have been subjected to the never failing selection of their climate and other external conditions. They exhibit a full and striking adaptation to these conditions, but also possess the latent capacity for assuming lowland characters as soon as they are transported into such environment. Obviously this capacity never becomes active on the mountains, and is always counteracted by selection. This agency is evidently without any effect, for as we have seen when dealing [795] with the experiments of Nageli, Bonnier and others, each single individual may change its habits and its aspect in response to transplantation. The climate has an exceedingly great influence on each individual, but the continuance of this influence is without permanent result. So much concerning ever-sporting varieties and double adaptations. We now come to the effects of a continuous selection of simple characters. Here the sugar-beets stand preeminent. Since Vilmorin's time they have been selected according to the amount of sugar in their roots, and the result has been the most striking that has ever been attained, if considered from the standpoint of practice. But if critically examined, with no other aim than a scientific appreciation of the improvement in comparison with other processes of selection, the support of the evidence for the theory of accumulative influence proves to be very small. The amount of sugar is expressed by percentage-figures. These however, are dependent on various causes, besides the real quantity of sugar produced. One of these causes is the quantity of watery fluid in the tissues, and this in its turn is dependent on the culture in dryer or moister soil, and on the amount of moisture in the air, and the same variety of sugar-beets [796] yields higher percentage-figures in a dry region than in a wet one. This is seen when comparing, for instance, the results of the analyses from the sandy provinces of Holland with those from the clay-meadows, and it is very well known that Californian beets average as high as 26% or more, while the best European beets remain at about 20%. As far as I have been able to ascertain, these figures however, are not indicative of any difference of race, but simply direct responses to the conditions of climate and of soil. Apart from these considerations the improvement reached in half a century or in about twenty to thirty generations is not suggestive of anything absolute. Everything is fluctuating now, even as it was at the outset, and equally dependent on continual care. Vilmorin has given some figures for the beets of the first generations from which he started his race. He quotes 14% as a recommendable amount, and 7 and 21 as the extreme instances of his analyses. However incorrect these figures may be, they coincide to a striking degree with the present condition of the best European races. Of course minor values are excluded each year by the selection, and in consequence the average value has increased. For the year 1874 we find a standard of 10-14% considered as normal, [797] bad years giving 10%, good years from 12% to 14% in the average. Extreme instances exceeded 17%. From that time the practice of the polarization of the juice for the estimate of the sugar has rapidly spread throughout Europe, and a definite increase of the average value soon resulted. This however, often does not exceed 14%, and beets selected in the field for the purpose of polarization come up to an average of 15 to 16%, varying downward to less than 10% and upward to 20 and 21%. In the main the figures are the same as those of Vilmorin, the range of variability has not been reduced, and higher extremes are not reached. An average increase of 1% is of great practical importance, and nothing can excel the industry and care displayed in the improvement of the beet-races. Notwithstanding this a lasting influence has not been exercised; the methods of selection have been improved, and the number of polarized beets has been brought up to some hundreds of thousands in single factories, but the improvement is still as dependent upon continuous selection as it was half a century ago. The process is practically very successful, but the support afforded by it to the selection theory vanishes on critical examination. [798] LECTURE XXVIII ARTIFICIAL AND NATURAL SELECTION The comparison of artificial and natural selection has furnished material support for the theory of descent, and in turn been the object of constant criticism since the time of Darwin. The criticisms, in greater part, have arisen chiefly from an imperfect knowledge of both processes. By the aid of distinctions recently made possible, the contrast between elementary species and improved races has become much more vivid, and promises to yield better results on which to base comparisons of artificial and natural selection. Elementary species, as we have seen in earlier lectures, occur in wild and in cultivated plants. In older genera and systematic species they are often present in small numbers only, but many of the more recent wild types and also many of the cultivated forms are very rich in this respect. In agriculture the choice of the most adequate elementary forms for any special purpose is acknowledged [799] as the first step in the way of selection, and is designated by the name of variety-testing, applying the term variety to all the subdivisions of systematic species indiscriminately. In natural processes it bears the title of survival of species. The fact that recent types show large numbers, and in some instances even hundreds of minor constant forms, while the older genera are considerably reduced in this respect, is commonly explained by the assumption of extinction of species on a correspondingly large scale. This extinction is considered to affect the unfit in a higher measure than the fit. Consequently the former vanish, often without leaving any trace of their existence, and only those that prove to be sufficiently adapted to the surrounding external conditions, resist and survive. This selection exhibits far-reaching analogies between the artificial and the natural processes, and is in both cases of the very highest importance. In nature the dying out of unfit mutations is the result of the great struggle for life. In a previous lecture we have compared its agency with that of a sieve. All elements which are too small or too weak fall through, and only those are preserved which resist the sifting process. Reduced in number they thrive and multiply and are thus enabled to [800] strike out new mutative changes. These are again submitted to the sifting tests, and the frequent repetition of this process is considered to give a good explanation of the manifold, highly complicated, and admirable structures which strike the beginner as the only real adaptations in nature. Exactly in the same way artificial selection isolates and preserves some elementary species, while it destroys others. Of course the time is not sufficient to secure new mutations, or at least these are only rare at present, and their occurrence is doubtful in historic periods. Apart from this unavoidable difference the analogy between natural and artificial selection appears to me to be very striking. This form of selection may be termed selection between species. Opposed to it stands the selection within the elementary species or variety. It has of late, alone come to be known as selection, though in reality it does not deserve this distinction. I have already detailed the historical evidence which gives preference to selection between species. The process can best be designated by the name of intraspecific selection, if it is understood that the term intraspecific is meant to apply to the conception of small or elementary species. I do not wish to propose new terms, but [801] I think that the principal differences might better become understood by the introduction of the word election into the discussion of questions of heredity. Election meant formerly the preferential choice of single individuals, while the derivation of the word selection points to a segregation of assemblies into their larger parts. Or to state it in a shorter way, individual selection is exactly what is usually termed election. Choosing one man from among thousands is to elect him, but a select party is a group of chosen persons. There would be no great difficulty in the introduction of the word election, as breeders are already in the habit of calling their choice individuals "elite," at least in the case of beets and of cereals. This intraspecific selection affords a second point for the comparison between natural and artificial processes. This case is readily granted to be more difficult than the first, but there can be no doubt that the similarity is due to strictly comparable causes. In practice this process is scarcely second in importance to the selection between species, and in numerous cases it rests upon it, and crowns it, bringing the isolated forms up to their highest possible degree of usefulness. In nature it does quite the same, adapting strains of individuals to the local conditions of their environment. Improved [802] races do not generally last very long in practice; sooner or later they are surpassed by new selections. Exactly so we may imagine the agency of natural intraspecific selection. It produces the local races, the marks of which disappear as soon as the special external conditions cease to act. It is responsible only for the smallest lateral branches of the pedigree, but has nothing in common with the evolution on the main stems. It is of very subordinate importance. These assertions of course, are directly opposed to the current run of scientific belief, but they are supported by facts. A considerable part of the evidence has already been dealt with and for our closing discussion only an exact comparison remains to be made between the two detailed types of intraspecific selection. In coming to this I will first dwell upon some intermediate types and conclude with a critical discussion of the features of artificial selection, which to my mind prove the invalidity of the conclusions drawn from it in behalf of an explanation of the processes of nature. Natural selection occurs not only in the wild state, but is also active in cultivated fields. Here it regulates the struggle of the selected varieties and improved races with the older types, and even with the wild species. In a previous [803] lecture I have detailed the rapid increase of the wild oats in certain years, and described the experiments of Risler and Rimpau in the running out of select varieties. The agency is always the same. The preferred forms, which give a larger harvest, are generally more sensitive to injurious influences, more dependent on rich manure and on adequate treatment. The native varieties have therefore the advantage, when climatic or cultural conditions are unfavorable for the fields at large. They suffer in a minor degree, and are thereby enabled to propagate themselves afterwards more rapidly and to defeat the finer types. This struggle for life is a constant one, and can easily be followed, whenever the composition of a strain is noted in successive years. It is well appreciated by breeders and farmers, because it is always liable to counteract their endeavors and to claim their utmost efforts to keep their races pure. There can be no doubt that exactly the same struggle exempt from man's intrusion is fought out in the wild state. Local races of wild plants have not been the object for field observations recently. Some facts however, are known concerning them. On the East Friesian Islands in the North Sea the flowers are strikingly larger and brighter colored than those of the same species on the [804] neighboring continent. This local difference is ascribed by Behrens to a more severe selection by the pollinating insects in consequence of their lesser frequency on these very windy isles. Seeds of the pines from the Himalayas yield cold-resisting young plants if gathered from trees in a high altitude, while the seeds of the same species from lower regions yield more sensitive seedlings. Similar instances are afforded by _Rhododendron_ and other mountain species. According to Cieslar corresponding differences are shown by seeds of firs and larches from alpine and lowland provinces. Such changes are directly dependent on external influences. This is especially manifest in experiments extending the cultures in higher or in more northern regions. The shorter summer is a natural agent of selection; it excludes all individuals which cannot ripen their seeds during so short a period. Only the short lived ones survive. Schubeler made very striking experiments with corn and other different cereals, and has succeeded in making their culture possible in regions of Norway where it formerly failed. In the district of Christiania, corn had within some few years reduced its lifetime from 123 to 90 days, yielding smaller stems and fewer kernels, but still sufficient to make its culture profitable under the existing conditions. [805] This change was not permanent, but was observed to diminish rapidly and to disappear entirely, whenever the Norwegian strain was cultivated in the southern part of Germany. It was a typical improved race, dependent on continual selection by the short summers which had produced it. Similar results have been reached by Von Wettstein in the comparison of kinds of flax from different countries. The analogy between such cultivated local races and the local races of nature is quite striking. The practice of seed exchange rests for a large part on the experience that the characters, acquired under the definite climatic and cultural conditions of some select regions, hold good for one or two, and sometimes even more generations, before they decrease to practical uselessness. The Probstei, the Hanna and other districts owe their wealth to this temporary superiority of their wheat and other cereals. Leaving these intermediate forms of selection, we now come to our principal point. It has already been discussed at some length in the previous lecture, but needs further consideration. It is the question whether intraspecific selection may be regarded as a cause of lasting and ever-increasing improvement. This is assumed by biologists who consider fluctuating variability as the main source of progression [806] in the organic world. But the experience of the breeders does not support this view, since the results of practice prove that selection according to a constant standard soon reaches a limit which it is not capable of transgressing. In order to attain further improvements the method of selection itself must be improved. A better and sharper method assures the choice of more valuable representatives of the race, even if these must be sought for in far larger numbers of individuals, as is indicated by the law of Quetelet. Continuous or even prolonged improvement of a cultivated race is not the result of frequently repeated selection, but of the improvement of the standard of appreciation. Nature, as far as we know, changes her standard from time to time only in consequence of the migrations of the species, or of local changes of climate. Afterwards the new standard remains unchanged for centuries. Selection, according to a constant standard, reaches its results in few generations. The experience of Van Mons and other breeders of apples shows that the limit of size and lusciousness may be soon attained. Vilmorin's experiments with wild carrots and those of Carriere with radishes lead to the same conclusion as regards roots. Improvements of flowers in [807] size and color are usually easy and rapid in the beginning, but an impassable limit is soon reached. Numerous other instances could be given. Contrasted with these simple cases is the method of selecting sugar beets. More than once I have alluded to this splendid example of the influence of man upon domestic races, and tried to point out how little support it affords to the current scientific opinion concerning the power of natural selection. For this reason it is interesting to see how a gradual development of the methods of selection has been, from the very outset, one of the chief aims of the breeders. None of them doubts that an improvement of the method alone is adequate to obtain results. This result, in the main, is the securing of a few percent more of sugar, a change hardly comparable with that progress in evolution, which our theories are destined to explain. Vilmorin's original method was a very simple one. Polarization was still undiscovered in his time. He determined the specific weight of his beets, either by weighing them as a whole, or by using a piece cut from the base of the roots and deprived of its bark, in order to test only the sugar tissues. The pieces were floated in solutions of salt, which were diluted until the pieces [808] began to sink. Their specific weight at that moment was determined and considered to be a measure of the corresponding value of the beet. This principle was afterwards improved in two ways. The first was a selection after the salt solution method, but performed on a large scale. After some few determinations, a solution was made of such strength as to allow the greater number of the beets to float, and only the best to sink down. In large vessels thousands of beets could be tested in this way, to select a few of the very heaviest. The other improvement was the determination of the specific weight of the sap, pressed out from the tissue. It was more tedious and more expensive, but more direct, as the influence of the air cavities of the tissue was excluded. It prepared the way for polarization. This was introduced about the year 1874 in Germany, and soon became generally accepted. It allowed the amount of sugar to be measured directly, and with but slight trouble. Thousands of beets could be tested yearly by this method, and the best selected for the production of seed. In some factories a standard percentage is determined by previous inquiries, and the mass of the beets is tested only by it. In others the methods of taking samples and clearing the sap have been improved so far as to allow the [809] exact determination of three hundred thousand polarization values of beets within a few weeks. Such figures give the richest material for statistical studies, and at once indicate the best roots, while they enable the breeder to change his standard in accordance with the results at any time. Furthermore they allow the mass of the beets to be divided into groups of different quality, and to produce, besides the seeds for the continuation of the race, a first class and second-class product and so on. In the factory of Messrs. Kuhn & Co., at Naarden, Holland, the grinding machine has been markedly improved, so as to tear all cell walls asunder, open all cells, and secure the whole of the sap within less than a minute, and without heating. It would take too long to go into further details, or to describe the simultaneous changes that have been applied to the culture of the elite strains. The detailed features suffice to show that the chief care of the breeder in this case is a continuous amelioration of the method of selecting. It is manifest that the progression of the race is in the main due to great technical improvements, and not solely to the repetition of the selection. Similar facts may be seen on all the great lines of industrial selection. An increasing appreciation [810] of all the qualities of the selected plants is the common feature. Morphological characters, and the capacity of yielding the desired products, are the first points that strike the breeder. The relation to climate and the dependence on manure soon follow; but the physiological and chemical sides of the problem are usually slow of recognition in the methods of selection. When visiting Mr. de Vilmorin at Paris some years ago, I inspected his laboratory for the selection of potatoes. In the method in use, the tubers were rubbed to pulp and the starch was extracted and measured. A starch percentage figure was determined for each plant, and the selection of the tubers for planting was founded upon this result. In the same way wheat has been selected by Dippe at Quedlinburg, first by a determination of its nitrogenous contents in general, and secondly by the amount of the substances which determine its value for baking purposes. The celebrated rye of Schlanstedt was produced by the late Mr. Rimpau in a similar manner and was put on the market between 1880 and 1890 and was received with great favor throughout central Europe, especially in Germany and in France. It is a tall variety, with vigorous stems and very long heads, the kernels of which are nearly double the size of those of the [811] ordinary rye, and are seen protruding, when ripe, from between the scales of the spikelets. It is unfit for poor soils, but is one of the very best varieties for soils of medium fertility in a temperate climate. It is equal in the production of grain to the best French sorts, but far surpassing them in its amount of straw. It was perfected at the farm of Schlanstedt very slowly, according to the current conceptions of the period. The experiment was started in the year 1866, at which time Rimpau collected the most beautiful heads from among his fields, and sowed their kernels in his experiment garden. From this first culture the whole race was derived. Every year the best ears of the strain were chosen for repeated culture, under experimental care, while the remainder was multiplied in a field to furnish the seeds for large and continually increasing areas of his farms. Two or three years were required to produce the quantity of seed of each kind required for all the fields of Schlanstedt. The experiment garden, which through the kindness of Mr. Rimpau I had the good fortune of visiting more than once between 1875 and 1878, was situated in the middle of his farm, at some distance from the dwellings. Of course it was treated with more care, and especially kept [812] in better conditions of fertility than was possible for the fields at large. A continued study of the qualities and exigencies of the elite plants accompanied this selection, and gave the means of gradually increasing the standard. Resistance against disease was observed and other qualities were ameliorated in the same manner. Mr. Rimpau repeatedly told me that he was most anxious not to overlook any single character, because he feared that if any of them might become selected in the wrong way, perchance unconsciously, the whole strain might suffer to such a degree as to make all the other ameliorations quite useless. With this purpose the number of plants per acre was kept nearly the same as those in the fields, and the size of the culture was large enough every year to include the best kernels of quite a number of heads. These were never separated, and exact individual pedigrees were not included in the plan. This mixture seemed to have the advantage of keeping up an average value of the larger number of the characters, which either from their nature or from their apparent unimportance had necessarily to be neglected. After ten years of continuous labor, the rye of Rimpau caught the attention of his neighbors, being manifestly better than that of ordinary [813] sowings. Originally he had made his cultures for the improvement of his own fields only. Gradually however, he began to sell his product as seed to others, though he found the difference still very slight. After ten years more, about 1886, he was able to sell all his rye as seed, thereby making of course large profits. It is now acknowledged as one of the best sorts, though in his last letter Mr. Rimpau announced to me that the profits began to decline as other selected varieties of rye became known. The limit of productiveness was reached, and to surmount this, selection had to be begun again from some new and better starting point. This new starting point invokes quite another principle of selection, a principle which threatens to make the contrast between artificial and natural selection still greater. In fact it is nothing new, being in use formerly in the selection of domestic animals, and having been applied by Vilmorin to his sugar beets more than half a century ago. Why it should ever have been overlooked and neglected in the selection of sugar beets now is not clear. The principle in itself is very simple. It agrees that the visible characters of an animal or a plant are only an imperfect measure for its hereditary qualities, instead of being the real criterion to be relied upon, as is the current belief. [814] It further reasons that a direct appreciation of the capacity of inheritance can only be derived from the observation of the inheritance itself. Hence it concludes that the average value of the offspring is the only real standard by which to judge the representatives of a race and to found selection upon. These statements are so directly opposed to views prevalent among plant breeders, that it seems necessary to deal with them from the theoretical and experimental, as well as from the practical side. The theoretical arguments rest on the division of the fluctuating variability into the two large classes of individual or embryonic, and of partial deviations. We have dealt with this division at some length in the previous lecture. It will be apparent at once, if we choose a definite example. Let us ask what is the real significance of the percentage figure of a single plant in sugar beets. This value depends in the first place, on the strain or family from which the beet has been derived, but this primary point may be neglected here, because it is the same for all the beets of any lot, and determines the average, around which all are fluctuating. The deviation of the percentage figure of a single beet depends on two main groups of external [815] causes. First come those that have influenced the young germs of the plant during its most sensitive period, when still an embryo within the ripening seed. They give a new limitation to the average condition, which once and forever becomes fixed for this special individual. In the second place the young seedling is affected during the development of its crown of leaves, and of its roots, by numerous factors, which cannot change this average, but may induce deviations from it, increasing or decreasing the amount of sugar, which will eventually be laid down in the root. The best young beet may be injured in many ways during periods of its lifetime, and produce less sugar than could reasonably be expected from it. It may be surpassed by beets of inferior constitution, but growing under more favorable circumstances. Considered from this point of view the result of the polarization test is not a single value, but consists of at least two different factors. It may be equal to the algebraic sum of these, or to their difference, according to whether the external conditions on the field were locally and individually favorable or unfavorable. A large amount of sugar may be due to high individual value, with slight subsequent deviation from it, [816] or to a less prominent character combined with an extreme subordinate deviation. Hence it is manifest that even the results of such a highly improved technical method do not deserve the confidence usually put in them. They are open to doubt, and the highest figures do not really indicate the best representatives of the race. In order to convey this conception to you in a still stronger manner, let us consider the partial variability as it usually shows itself. The various leaves of a plant may noticeably vary in size, the flowers in color, the fruits in flavor. They fluctuate around an average, which is assumed to represent the approximate value of the whole plant. But if we were allowed to measure only one leaf, or to estimate only one flower or fruit, and be compelled to conclude from it the worth of the whole plant, what mistakes we could make! We might indeed hit upon an average case, but we might as easily get an extreme, either in the way of increase or of decrease. In both cases our judgment would be badly founded. Now who can assure us that the single root of a given beet is an average representative of the partial variability? The fact that there is only one main root does not prove anything. An annual plant has only one stem, but a perennial species has many. The average height of the last is a [817] reliable character, but the casual height of the former is very uncertain. So it is with the beets. A beet may be divided by its buds and give quite a number of roots, belonging to the same individual. These secondary roots have been tested for the amount of sugar, and found to exhibit a manifest degree of variability. If the first root corresponded to their average, it might be considered as reliable, but if not anyone will grant that an average is more reliable than a single determination. Deviations have as a fact been observed, proving the validity of our assertion. These considerations at once explain the disappointment so often experienced by breeders. Some facts may be quoted from the Belgian professor of agriculture at Gembloux, the late Mr. Laurent. He selected two beets, from a strain, with the exceptional amount of 23% sugar, but kept their offspring separate and analyzed some 60 of each. In both groups the average was only 11-12%, the extremes not surpassing 14-15%. Evidently the choice was a bad one, notwithstanding the high polarization value of the parent. Analogous cases are often observed, and my countrymen, Messrs. Kuhn & Co., go so far as to doubt all excessive variants, and to prefer beets with high, but less extraordinary percentages. Such are to be had in larger numbers [818] and their average has a good chance of exemption from a considerable portion of the doubts adhering to single excessive cases. It is curious to note here what Louis de Vilmorin taught concerning this point in the year 1850. I quote his own words: "I have observed that in experiments on heredity it is necessary to individualize as much as possible. So I have taken to the habit of saving and sowing separately the seeds of every individual beet, and I have always found that among the chosen parent plants some had an offspring with a better average yield than others. At the end I have come to consider this character only, as a standard for amelioration." The words are clear and their author is the originator of the whole method of plant breeding selection. Yet the principle has been abandoned, and nearly forgotten under the impression that polarization alone was the supreme guide to be relied upon. However, if I understand the signs rightly, the time is soon coming when Vilmorin's experience will become once more the foundation for progress in breeding. Leaving the theoretical and historical aspects of the problem, we will now recall the experimental evidence, given in a former lecture, dealing with the inheritance of monstrosities. I have shown that in many instances monstrosities [819] constitute double races, consisting of monstrous and of normal individuals. At first sight one might be induced to surmise that the monstrous ones are the true representatives of the race, and that their seeds should be exclusively sown, in order to keep the strain up to its normal standard. One might even suppose that the normal individuals, or the so-called atavists, had really reverted to the original type of the species and that their progeny would remain true to this. My experiments, however, have shown that quite the contrary is the case. No doubt, the seeds of the monstrous specimens are trustworthy, but the seeds of the atavists are not less so. Fasciated hawkweeds and twisted teasels gave the same average constitution of the offspring from highly monstrous, and from apparently wholly normal individuals. In other words the fullest development of the visible characteristic was not in the slightest degree an indication of better hereditary tendencies. In unfavorable years a whole generation of a fasciated race may exhibit exclusively normal plants, without transmitting a trace of this deficiency to the following generation. As soon as the suitable conditions return, the monstrosity reassumes its full development. The accordance of these facts with the experience [820] of breeders of domestic animals, and of Louis de Vilmorin, and with the result of the theoretical considerations concerning the factors of fluctuation has led me to suggest the method of selecting, which I have made use of in my experiments with tricotyls and syncotyls. Seedling variations afford a means of counting many hundreds of individuals in a single germinating pan. If seed from one parent plant is sown only in each pan, a percentage figure for the amount of deviating seedlings may be obtained. These figures we have called the hereditary percentages. I have been able to select the parent plants after their death on the sole ground of these values. And the result has been that from varieties which, on an average, exhibited 50-55% deviating seedlings, after one or two years of selection this proportion in the offspring was brought up to about 90% in most of the cases. _Phacelia_ and mercury with tricotylous seedlings, and the Russian sunflower with connate seed leaves, may be cited as instances. Besides these tests, others were performed, based only on the visible characters of the seedlings. The result was that this characteristic was almost useless as a criterion. The atavists gave, in the main, nearly the same hereditary percentages as the tricotyls and syncotyls, and [821] their extremes were in each case far better constituted than the average of the chosen type. Hence, for selection purposes, the atavists must be considered to be in no way inferior to the typical specimens. If it had been possible to apply this principle to twisted and fasciated plants, and perhaps even to other monstrosities, I think that it will readily be granted that the chance of bringing even these races up to a percentage of 90% would have been large enough. But the large size of the cultures required for the counting of numerous groups of offspring in the adult state has deterred me from making such trials. Recently however, I have discovered a species, _Viscaria oculata_ which allows of counting twisted specimens in the pans, and I may soon be able to obtain proofs of this assertion. The validity of the hereditary percentage as a standard of selection has, within the last few years, been recognized and defended by two eminent breeders, W.A. Hays in this country and Von Lochow in Germany. Both of them have started from the experience of breeders of domestic animals. Von Lochow applied the principle to rye. He first showed how fallacious the visible characters often are. For instance the size of the kernels is often dependent on their number in the head, and if this number is [822] reduced by the injurious varietal mark of lacunae (Luckigkeit), the whole harvest will rapidly deteriorate by the selection of the largest kernels from varieties which are not quite free from this hereditary deficiency. In order to estimate the value of his rye plants, he gathers the seed of each one separately and sows them in rows. Each row corresponds to a parent plant and receives 200 or 150 seeds, according to the available quantity. In this way from 700 to 800 parent plants are tested yearly. Each row is harvested separately. The number of plants gives the average measure of resistance to frost, this being the only important cause of loss. Then the yield in grain and straw is determined and calculated, and other qualities are taken into consideration. Finally one or more groups stand prominent above all others and are chosen for the continuation of the race. All other groups are wholly excluded from the "elite," but among them the best groups and the very best individuals from lesser groups are considered adequate for further cultivation, in order to produce the commercial product of the race. As a matter of fact the rye of Von Lochow is now one of the best varieties, and even surpasses the celebrated variety of Schlanstedt. It was only after obtaining proof of the validity [823] of his method that Von Lochow decided to give it to the public. W.M. Hays has made experiments with wheat at the Minnesota Agricultural Experiment Station. He chose a hundred grains as a proper number for the appreciation of each parent plant, and hence has adopted the name of "centgener power" for the hereditary percentage. The average of the hundred offspring is the standard to judge the parent by. Experience shows at once that this average is not at all proportional to the visible qualities of the parent. Hence the conclusion that the yield of the parent plant is a very uncertain indication of its value as a parent for the succeeding generation. Only the parents with the largest power in the centgener of offspring are chosen, while all others are wholly discarded. Afterwards the seeds of the chosen groups are propagated in the field until the required quantities of seed are obtained. This centgener power, or breeding ability, is tested and compared for the various parent plants as to yield, grade, and percentage of nitrogenous content in the grain, and as to the ability of the plant to stand erect, resist rust, and other important qualities. It is evident that by this test of a hundred specimens a far better [824] and much more reliable determination can be made than on the ground of the minutest examination of one single plant. From this point of view the method of Hays commands attention. But the chief advantage lies in the fact that it is a direct proof of that which it is desired to prove, while the visible marks give only very indirect information. Thus the results of the men of practice are in full accordance with those of theory and scientific experiment, and there can be little doubt that they open the way for a rapid and important improvement. Once attained, progress however, will be dependent on the selection principle, and the hereditary percentage, or centgener power or breeding ability, must be determined in each generation anew. Without this the race would soon regress to its former condition. To return to our starting point, the comparison of artificial and natural selection. Here we are at once struck by the fact that it is hardly imaginable, how nature can make use of this principle. In some measure the members of the best centgener will manifestly be at an advantage, because they contain more fit specimens than the other groups. But the struggle for existence goes on between individuals, and not between groups of brethren against groups of [825] cousins. In every group the best adapted individuals will survive, and soon the breeding differences between the parents must vanish altogether. Manifestly they can, as a rule, have no lasting result on the issue of the struggle far existence. If now we remember that in Darwin's time this principle, breeding ability, enjoyed a far more general appreciation than at present, and that Darwin must have given it full consideration, it becomes at once clear that this old, but recently revived principle, is not adequate to support the current comparison between artificial and natural selection. In conclusion, summing up all our arguments, we may state that there is a broad analogy between breeding selection in the widest sense of the word, including variety testing, race improvement and the trial of the breeding ability on one side, and natural selection on the other. This analogy however, points to the importance of the selection between elementary species, and the very subordinate role of intraspecific selection in nature. It strongly supports our view of the origin of species by mutation instead of continuous selection. Or, to put it in the terms chosen lately by Mr. Arthur Harris in a friendly criticism of my views: "Natural selection may explain the survival [826] of the fittest, but it cannot explain the arrival of the fittest." A _Abies concolor fastigiata_, 618 _Acacia_, 176, 196, 217, 458, 697 bastard, 343, 617, 618, 664, 665, 666 _Acer compestre nanum_, 612 _Achillea millefolium_, 131, 132, 441 Adaptation, 702 double, 430, 451, 452, 454, 455, 457, 458, 642 _Aegilops ovata_, 265 _speltaeformis_, 265 _Agave vivipara_, 684 _Ageratum coeruleum_, 612 _Agrostemma Coronaries bicolor_, 125 _Githago_, 282 _nicaeensis_, 162 _Agrotis_, 204 Alder, cut-leaved, 147, 596 Alfalfa, 264 Algae, 699 Allen, Grant, 237 _Alliaria_, 638 _Alnus glutinosa laciniata_, 615 Alpine plants, 437, 695, 794 _Althaea_, 490 Amaranth, 282, 452 _Amaranthus caudatus_, 282 _Amaryllis_, 272, 275, 762 brasiliensis_, 275 leopoldi_, 275 pardina_, 275 psittacina_, 275 vittata_, 275 Amen-Hotep, 697 _Ampelopsis_, 239 _Amygdalus persica laevis_, 126 _Anagallis arvensis_, 162 _Androsace_, 634 _Anemone_, 266, 331 _coronaria_, 241, 491 var. "Bride," 510 _magellanica_, 266 _sylvestris_, 266 _Anemone_, garden, 241 Annee, 760 Anomalies, taxonomic, 658, 685 _Anthemis_, 236 _nobilis_, 130 _Anthurium scherzerianum_, 639 _Antirrhinum majus_, 315 _luteum rubro-striatum_, 315 Apetalous flowers, 622 Apples, 134, 240, 328, 454, 806 elementary species, 75 method of cultivating, 76 origin of cultivated varieties, 73 use by the Romans, 74 "Wealthy," 78, 79 wild, 73, 74, 75, 76 _Aquilegia chrysantha_, 161 _Arabis ciliata glabrata_ _hirsuta glaberrima_, 126 _Aralia crassifolia_, 662 Arbres fruitiers ou Pomonomie belge, 76 _Aralia papyrifera_, 662 Arctic flora, 695 _Arnica_, 494 _montana_, 236 Aroids, 222, 631, 639 Artemisias, 131 Artificial selection, 18, 71, 77, 93, 95, 743, 744, 798, 826 first employed, 72, 92 nature of, 19 _Arum maculatum immaculatum_, 125 Ascidia, 310, 366, 367, 427, 428, 669, 670, 671, 672, 673, 674, 675 Ash, 135, 341 one-bladed, 666, 667 weeping, 196, 596 Ashe, 343 Aster, 132, 152, 242 seashore, 200, 282 _Aster Tripolium_, 132, 200, 236, 282, 410 _Astragalus alpinus_, 696 Atavism, 154, 170, 172, 175, 176, 178, 182, 185, 187, 188, 198, 220, 222, 226, 235, 344, 354, 399, 405, 411, 660, 661 bud, 183, 226 definition of, 170, 631 false, 185, 187 negative, 344 positive, 344 seed, 176 systematic, 174, 222, 630-657 Atavists, 156, 201 heredity of, 412 _Atropa Belladonna lutea_, 592 _Aubretia_, 241 _Avena fatua_, 100, 207 _Azalea_, 178, 322 _Azolla caroliniana_, 239 B Babington, _Manual of British Botany_, 36, Bailey, 78, 306, 684 Balsams, 334 Bananas, 90, 134 Banyan, 244 Barberry, 133, 180 European, 270 purple, 596 _Barbarea vulgaris_, 427 Barley, 98, 105, 133, 203, 678, 679 "Nepaul," 203, 676, 677, 679, 681, 682 Bastard-acacia, 133, 136, 140 Bateson, 250 Bauhin, Caspar, 72, 610 Baumann, 618 Beans, 90, 152, 327, 727, 735 Bedstraw, 648 Beech, 133, 135, 242 cut-leaved, 179, 196, 616 laciniated, 196 oak-leaved, 595 purple, 196, 593, 595 Beeches, 427 fern-leaved, 147 Beets, 68, 72, 92, 93, 792, 796, 801, 815, 817, 818 Californian, 796 European, 796 forage, 71, 72, 791 salad, 71 Beet-sugar, 67, 68, 69, 70, 71, 109, 165, 717, 791, 807, 813, 814 _Begonia_, 218, 366, 509, 765 ever-flowering, 148 tuberous, 272 _clarkii_, 272 _davisii_, 272 _rosiflora_, 272 _sedeni_, 273 _semperflorens_, 133, 148, 620 _Begonia_ bulbous, 372 _veitchi_, 272 Behrens, 804 Belladonna, 145 _Bellis perennis_, 236 _perennis plena_, 195 Bentham, 237 Bentham & Hooker, _Handbook of British Flora_, 36 _Berberis_, 133, 180, 455 _ilicifolia_, 270 _vulgaris_, 270 Bertin, 596 _Berula angustifolia_, 457 Bessey, 660 _Beta maritima_, 69 _patula_, 69, 70 _vulgaris_, 69, 70 _Betula_, 132 Between-race, 358 Bewirkung, Theorie der directen (Nageli), 448 _Biastrepsis_, 402 _Bidens_, 131 _atropurpurea_, 131 _cernua_, 131, 158 _leucantha_, 131 _tripartite_, 131 Bilberries, 577 Bindweed, 41924 Binomium, of Newton, 767 Birch, 133, 243 cut-leaved, 596, 616 fastigiate, 618 fern-leaved, 179 _Bisoutella_, 282 _laevigata glabra_, 125 Bitter-sweet, 125 Blackberry, 268, 768 "Paradox," 769 Blue-bells, variation in, 54, 491, 577 Blueberries, 769 Blue-bottle, 499, 507, 509, 510 Blueflag, atavism of, 172 _Boehmeria_, 675 _bilboa_, 685 Bonnier, 439, 441, 442, 444, 451, 795 Boreau, 663 Brambles, 126, 127, 147, 239, 244, 245, 268, 740, 769, 663 _Brassica_, 244 Braun, 738 Braun and Schimper, 494 Bread-fruits, 90 Briot, 618 Britton and Brown's Flora, 162 Brooks, 711 Broom, 140 prickly, 217 Broom-rape, 220 _Broussonetia papyifera dissecta_, 616 _Brunella_, 146, 268 _vulgaris_, 577 _vulgaris alba_, 201 _Bryophyllum calycinum_, 218 Buckwheat, 452 Bud-variation, 750 Buds, adventitious, 218 Burbank, Luther, 57, 79, 116, 134, 268, 758, 768, 769, 784 Buttercup, 331, 357, 410, 725, 740 Asiatic, 241 C Cabbages, 428, 684 atavism in, 638 origin of varieties, 621 Cactuses, 444 Cactus-dahlia, 625 _Calamintha Acinos_, 437, 452 Calamus root, 222 _Calendula officinalis_, 502 _Calliopsis tinctoria_, 195 _Calluna_, 146 _vulgaris_, 437, 577 _Caltha_, 490 _palustris_, 331 _Camelina_, 684 _Camellia_, 178, 323 _japonica_, 368 Camellias, 331 Camomile, 130, 132, 156, 366, 494, 503, 509, 512 _Campanula persicifolia_, 151, 234 _rotundifolia_, 437 Campion, 283, 302, 304 evening, 281 red, 238 _Canna_, 751, 759, 761 _indica_, 760 "Madame Crozy," 760, 761 _nepalensis_, 760 _warczewiczii_, 760 _Capsella Bursa-pastoris apetala_, 585 _heegeri_, 22, 582, 583, 684 _Carex_, 53 Carnation, 178, 241, 491 wheat-ear, 227 _Carpinus Betulus heterophylla_, 180 Carriere, 491, 596, 612, 806 Carrots, 806 Catch-fly, 419 Carboniferous period, 699 _Casuarina quadrivalvis_, 649 Cauliflowers, origin of, 621 Caumzet, 614 Causation, theory of direct, (Nageli), 448 Cedar, pyramidal, 618 Celandine, 147, 245, 280, 365 oak-leaved, 603, 610, 611 _Celosia_, 621 _Celosia cristata_, 327, 411 _Centaurea_, 242 Centgener power, 20, 822 _Centranthus macrosiphon_, 424 _Cephalotaxus_, 170, 226 _pedunculata fastigiata_, 169 Cereals, 105, 106, 107, 119, 801, 804 origin of cultivation, 104 Character-units, 632 Charlock, 424 _Cheiranthus_, 490 _Cheiri_, 370 _Cheiri gynantherus_, 371 _Chelidonium laciniatum_, 22, 609 _majus_, 147, 365, 600, 610, 611 _majus foliis quernis_, 610 Cherries, 79 Cherry, bird's, 617 Chestnuts, 427 Chromosomes, 306 _Chrysanthemum_, 178, 274 corn, 739 _Chrysanthemum carinatum_, 494 _coronarium_, 161, 202, 510 _grandiflorum_, 739 _imbricatum_, 494 _indicum_, 490 _inodorum_, 503 _inodorum plenissimum_, 336 new double, 501 _segetum_, 202, 493, 504, 729 _segetum_, var. _grandiflorum_, 43, 495, 498, 504, 504 _Chrysopogon montanus_, 450 Cieslar, 804 _Cineraria cruenta_, 514 Cinquefoil, 52 _Clarkia_, 420 _elegans_, 198 _pulchella_, 282 _pulchella carnea_, 162 _Clematis Vitalba_, 662 _Viticella nana_, 612 Clover, 80, 102, 674 crimson (Italian), 353, 358, 359, 360 five-leaved, 340, 362, 374, 431, 509, 789 four-leaved, 340, 346, 352 red, 235, 281 white, 133, 366 Clusius, 610 _Cochlearia anglica_, 52 _danica_, 52 _officinalis_, 52 Coconut, 67, 82, 83, 87, 88, 89 dispersal of, 85, 89 geographic origin of, 88,89 Coconut-palm, 84, 88 Cockerell, T.D.A., 139, 140, 591 Cocklebur, 139 Cockscomb, 165, 327, 356, 411, 621 _Cocos nucifera stupposa_, 83, 84 _cupuliformis_, 82 _rutila_, 82 _Codiaeum appendicularum_, 673 _Colchicum_, 490 _Coleus_, 132 Columbine, 725 yellow, 161 Columbus, 89, 118 Columella, 106 Composites, 130, 131, 336, 723, 778 Conifers, 168, 226, 239, 455 weeping, 617 Connation, of petals, 660, 661 "Conquests," 242 Contra-selection, 425 Cook, 84, 86, 88, 89 Corn, 81, 90, 118, 119, 135, 283, 287, 288, 775, 786, 788, 804 American, 205 Corn-cockle, 162 Corn-chrysanthemum, 739 Corn-flowers, 491, 92 Corn, "Forty-day," 118 "Harlequin," 327 sterile variety of, 622 sugar, 135, 158 "Tuscarora," 205 Corn-marigold, 493, 494 Cornel berry, yellow, 196 Cornaceae, 675 _Cornu_, 338 _Cornus Mas_, 196 Correlation, 142 _Corylus_, 133 _Avellana_, 181 _tubulosa_, 181 Cotton, 725 Cotyledon, 674 variation in, 416 _Crambe maritima_, 621 Cranesbill, 599 European, 628 meadow, 322 _Crataegus_, 196 _oxyacantha_, 132 Crowfoot, 331 corn, 283 _Crepis biennis_, 410, 411 Cress, Indian, 192 Crosses bisexual, 255, 276, 294, 298 reciprocal, 279 unisexual, 255, 261 varietal (see Hybrids) _Croton_, 673, 674 Crozy, 760, 762 Crucifers, 222, 635 _Cryptomeria_, 169, 226 _japonica_, 239 Cucumbers, 118 _Cucumis_, 52 _Cucurbita_, 52 Cultivated plants, 65, 66 elementary species of, 62 improvement of, 92 mixed nature of, 96, 118 origin of, 91 Currants, 79 Californian, 270 flowering, 166 "Gordon's," 270 Missouri, 270 white, 158 white-flowered, 167 Cuttings, 721 _Cyclamen_, 323, 355, 627, 684 Butterfly, 627 _vernum_, 619 _Cypripedium caudatum_, 487 _Cytisus adami_, 271 _candicans Attleyanus_, 367 _Laburnum_, 271 _prostratus_, 139 _prostratus ciliata_, 125 _purpureus_, 271 _spinescens_, 139 D _Dahlia_, 131, 241, 272, 625 cactus, 625 "Jules Chretien," 628 purple-leaved, 626 "surprise," 230 tubular, 627 [sic] 274, 490, 764 first double ones, 490 green, 227, 229, 230 Daisies, 131, 132, 494 double, 195 hen-and-chicken, 514 ox-eye, 202 Shasta, 769 yellow, 202 Dandelion, 411 parthenogenesis, 61 variations in, 60 Daphne Mezereum, 146 Darwin, 1, 2, 3, 4, 5, 6, 7, 18, 76, 85, 93, 109, 110, 180, 196, 205, 206, 242, 306, 324, 338, 448, 571, 604, 612, 689, 702, 710, 715, 743, 798, 825 Darwin, George, 711 Darwinian theory, 461 basis of, 5 Date, 134 _Datura Stramonium_, 139, 142 _Stramonium inermis_, 300 _Tatula_, 139, 142, 300 Dead-nettle, 237 De Bary, 38, 47, 49 De Candolle, 76, 84, 85, 89, 228, 370, 403, 621 Alphonse, 74, 129, 226 A.P., 129 Casimir, 659, 676 De Graaff, 275 _Delphinium Ajacis_, 192 Deniau, 617 Descent, theory of, 690, 694, 702, 707, 716, 798 De Serres, Olivier, 72 _Desmodium gyrans_, 655, 656, 663, 664, 65 Dewberry, California, 269 _Dianthus barbatus_, 322, 648 twisted variety, 408 Diatoms, 699 Dictoyledons ancestors of monocotyledons, 15 _Digitalis parviflora_, 161, 640 _purpurea_, 483 pelorism of, 482 Dimorphism, 445, 447, 454, 457, 458 Dippe, 810 _Dipsacus fullonum_, 402 sylvestris_, 402, 402 Dominant character, 280 Double flowers poppies 490 production of, 489 types of, 330 Double races (see also ever-sporting varieties), 419, 427, 428 Dubois, Eugene, 712 Duchesne, 185, 188, 596 Duckweed, 222 _Draba_, 692, 693 verna, 47, 50, 51, 53, 125, 126, 518, 533, 546, 547, 561 _Dracocephalum moldavicum_, 419 Dragon-head, 419 _Drosera anglica_, 268 _filiformis_, 268 _intermedia_, 268 _obovata_, 267 _rotundifolia_, 268 E Earth, age of, 710 Edelweiss, 438 Eichler, 660 Election, 801 Electric light, growth in, 442 Elementary species, 11, 13, 32, 67, 74, 76, 77, 78, 79, 91, 95, 116, 119, 124, 126, 128, 129, 207, 238, 252, 256, 307, 430, 435, 695, 696, 698, 702, 715, 787, 798, 800, 825 apples, 75 coconut, 82 corn, 81 cultivated plants, 62 definition of, 12, 35, 127 flax, 80 how produced, 16, 248 hybrids of, 253, 255 mutation of, 141 origin of, 459, 603 origin of, how studied, 463 selection of, 92 varieties vs., 14, 15, 141, 152, 224, 243, 247, 251, 495 Elm, 136, 219, 239, 427 _Epilobium_, 268 _hirsutum_, 683 _hirsutum cruciatum_, 588 _montanum_, 269 _tetragonum_, 269 _Equisetum Telmateja_, 642, 649 _Erica Tetralix_, 577, 661 Ericaceae, 146, 660 _Erigeron _Asteroides_, 450 _canadensis_, 132, 236, 453, 600, 695 _Erodium_, 146 _cicutarium album_, 161 _Erucastrum_, 630, 638, 639 _pollichii_, 222, 637 _Eryngium campestre_, 674 _maritimum_, 674 _Erysimum cheiranthoides_, 638 _Erythraea pulchella_, 452 _Erythrina_, 621 _Crista-galli_, 620 Eschcholtzias, 59 Esimpler, 337 _Eucalyptus citriodora_, 669 _Globulus_, 217 _Euphorbia Ipecacuanha_, 55 Evening-primrose, 62, 204, 256, 424, 686, 687, 688, 690, 691, 694, 695, 699, 702, 703, 705, 707, 708, 713, 747, 793 Evolution, 93, 685, 686, 689, 704, 707, 709, 710, 713, 718 degressive, 222, 223, 249 progression in, 630 progressive, 221, 222, 223, 248 regression in, 630 regressive, 221, 222; 223, 24 retrograde, 221, 631 Extremes, asexual multiplication of, 742, 769 F Fabre, 265 _Fagus_, 133 _Fagus sylvatica pectinata_, 179 Fan, genealogical, 700 Fasciated stems, 409, 412 Ferns, 63 cristate, 427 plumose, 427 _Ficaria_, 53 _Ficus radicans_, 436 _religiosus_, 244 _repens_, 436 _stipulata_, 436 _ulmifolia_, 436 Figs, 436 _Filago_, 52 Fir, 134, 804 Fittest, survival of, 826 Flax, 80, 805 springing, 80 threshing, 80 white-flowered, 158, 160 Fleabane, Canada, 132, 236 Flowers, gamopetalous, 660 Fluctuability embryonic, see Fluctuation, individual Fluctuation, 708, 715, 716, 718, 719, 724, 737, 741 curves of, 729, 794 defined, 191 individual, 718, 723, 732, 741, 745, 749, 788 mutation vs. 7, 16, 719 partial, 718, 723, 732, 741, 745, 748, 749, 771 inadequate for evolution, in elementary species, 19 nature of, 18 specific and varietal characters vs. 17 Forget-me-not, 368 Fothergill, John, 521 Foxglove, 163 peloric, 164, 356, 367 yellow, 161, 640 _Fraxinus excelsior monophylla_, 667 _exheterophylla_, 667 _simplici folio_, 667 French flora (Grenier and Godron), 433 Fries on _Hieracium_, 60 Frostweed, 440 species of, 52 _Fuchsia_, 272, 355 Fuchsias, 491 G Gaertner, 279 _Galeopsis Ladanum canescens_, 139 _Galium_, 648 _Aparine_, 409, 648 _elatum_, 52 _erectum_, 52 _Mollugo_, 62 _verum_, 648 Gallesio, 138 Galton, 736, 776 Gamopetaly, 662 Garden-pansy, origin of, 38 Garlic, 638 Gauchery, 452 Geikie, 711 Genera artificial character of, 36 polymorphous, 692 _Gentiana punctata concolor_, 125 Gentians, 577 Georgics (Vergil), 106 _Geranium pratense_, 323, 628 _album_, 628 _pyreniacum_, 599 German flora (Koth), 432 Geum, 282 Gherkins, 118 Gideon, Peter M., 78 Glacial period, 696 _Gladiolus_, 241, 272, 274, 368, 765 _cardinalis_, 275 _gandavensis_, 275 _psittacinus_, 275 _purpureo-auratus_, 275 _Glaucium_, 241 _Gleditschia sinensis_, 614 _triacanthos pendula_, 617 _Gloxinia_, 282, 485 erect, 626 _Gloxinia erecta_, 485 peloric variety, 485 _Gnaphalium Leontopodium_, 438 _Godetia amoena_, 161 Godetias, 59, 232 Godron, 265, 432 Goeppert, 370 Gooseberry, 79, 140, 626 red, 133, 165, 241 Grapes, 90, 158, 328 Grape-hyacinth, _plumosa_, 134 Grasses, 102, 631, 681 Grenier, 433 Groundsel, 132 Growth, nutrition and, 714, 720, 722 Guelder-rose, 134, 239 Gum-tree, Australian, 217 _Gypsophila paniculata_ twisted variety, 409 H Haeckel, 707 Half-races, 358, 372, 409, 419, 424, 427, 428 Hall, 444 Hallet, F.F., 109 Harebell, 232 peach-leaved, 234 Harris, Arthur, 825 Harshberger, John W., 591 on _Euphorbia_ in New Jersey, 55 Hawksbeard, 410, 411, 412 Hawkweed, 411, 439, 443, 819 Hawkweeds seeding without fertilization, 61 Hawthorn, white, 132 Hays, W.M. on individual selection, 20, 94, 95, 117, 821, 823, 824 Hazelnut, 133, 181, 242 Hazels, cut-leaved, 596,-616 Heath family, 146, 222, 660 Heaths, origin of, 662 Heather, 577 _Hedera Helix arborea_, 437 Hedgehog burweed, 140 _Hedys_Arum_, 664 Heeger, 582 Heer, Oswald, 74, 105 Heinricher, 172, 173, 174 _Helianthemum_, 53, 125, 126, 561 _apenninum_, 52 _pilosum_, 52 _polifolium_, 52 _pulverulentum_, 52 _vulgare_, 440 _Helichrysum_, 420 _Helwingia_, 678, 678, 682 _rusciflora_, 675 Hemp, 419 Henbane, 282 _Hepatica_, 322, 490 Heredity, 731, 734, 818 bearers of, 632 in teasels, 642 _Hesperis_, 241, 322 _matronalis_, 323, 411 _Heylandia latebrosa_, 450 _Hibiscus Moscheutos_, 591 _Hieracium_, 59, 439 _alpinum_, 696 Hildebrand, 160, 240, 241 Hoffman, 160, 662 Hofmeister, 160, 370, 480 Holbein, 164, 596 Holly, 140, 196 Holtermann, 449, 451 Hollyhock, 427 Honeysuckle, 674 ground, 443 _Hordeum distichum_, 677 _hexastichum_, 677, 678 _tetrastichum_, 677 _trifurcatum_, 676, 678 _vulgare trifurcatum_, 203 Hornbeam, European, 180 Horse-chestnut, 219 thornless, 234 Horsetail, Canadian, 695 European, 649 Horsetail, family, 641 Horse-weed, 132 Canadian, 452 _Hortensia_, 134, 181 Horticulture, mutations in, 604 Houseleek, 370, 371 Hunneman, John, 521 Hyacinths, 178, 322 white, 160 Hybrids, 58, 201, 202, 206, 250, 575 between elementary species, 253 constant, 263, 264, 265, 266, 267, 268, 269 law of varietal, 716 Mendelian, 324 nature of, 20 species, 256, 260 splitting of, 210 varietal, 208, 209, 247, 277, 278, 279, 281, 285, 293, 294 Hybridization, 706, 751, 752, 758, 759, 764 _Hydrocotyle_, 668 _Hyoscyamus niger_, 282 _pallidus_, 283 _Hypericum perforatum_, 725 _Hyssopus officinalis_, 161 I _Iberis umbellata rosea_, 195 Improved races, inconstancy of 770-797 Indian cress, 668 pelorism of, 485 Indian pipe, 661 Ipecac spurge, 55 _Iris_, 456 _falcifolis_, 172 _kaempferi_, 174 _lortetii_, 521 _pallida_, 172 _pallida abavia_, 681 Isolation, 108 Ivy, 436 J Jacob's ladder, 200, 202 Jacques, 614 Jacquin, 52, 632 Jaggi, 594, 595 Jaeger, 228, 662 Jalappa, 165 Janczewski, 266 Japanese plum, 58 _Jasminum Sambac_, 662 Joly, 712 Jordan, Alexis, 45, 47, 49, 50, 129 experiments with species, 37, 40 _Juncus effusus spiralis_, 684 Juniper, 684 K Kapteyn, 716 Kelvin, Lord, 720, 711 Kerner von Marilaun, 266, 267 Keteleer, 618 Knight, 390, 719, 720 Koch, 433, 667 Koelreuter, 279 Korshinsky, 609, 612, 614, 617, 667 Krelage, 510, 619 Kuhn & Co., Messrs., 801, 809, 817 L _Labiates_, 237 pelories of, 577 _Labiatiflorae_, pelorism of, 468 Labrador tea, 661 _Laburnum_, 270, 284, 342 oak-leaved 147, 179 pelorism of, 485 _Lactuca_, 52 _Scariola_, 456 Lagasca, Mariano, 96, 97, 114 Lamarck, 1, 447, 461, 522, 522 Lamarckism objections to, 449 _Lamium album_, 237 _maculatum_, 237 pelorism of, 486 _purpureum_, 237 Larch, 804 Larkspur, 124, 192, 311, 452 hybrid, 213 white, 160 Latency, 657 individual, 219 specific, 246 systematic, 219, 220, 235 varietal, 246 Latent characters, 216 _Lathyrus odoratus_, 776 _Laurea pinnatifida_, 450 Laurel, lady's, 146 Laurent, 802 Leaves, cleft, 685 variegated, 426, 431 LeBrun, Mme., 614 Le Couteur, 96, 97, 107, 108, 114, 115, 116, 742 _Ledum_, 222, 661 _Lemna_, 222 Lemoine, 762, 762 Lettuce, 684 crisped, 158 prickly, 456 Life, struggle for, 103, 119, 120 Lilacs, 59, 769 double, 762 _Lilium candidum flore pleno_, 331 _pardalium_, 116 Lime-tree, 355, 366, 428, 669 fern-leaved, 147 _Linaria_, 467, 471, 480 _dalmatica_, 482 _genistifolia_, 267 _italica_, 267 _vulgaris_, 267, 471 _vulgaris peloria_, 464 Lindley, 63, 129, 506 Linnaeus, 32, 33, 129, 132, 256, 663 on the idea of species, 11, 13 on origin of species, 2, 34 on primroses, 52 _Linum angustifolium_, 80 _crepitans_, 81 _usitatissimum_, 80, 161 Link, 466 Liver-leaf, 322 _Lobelia syphilitica_, 161 _Lonicera etrusca_, 640 _tartarica nana_, 614 Lorenz, Chr., 482 Lothelier, 454 _Lotus corniculatus_, 442 _corniculatus hirsutus_, 139 London, 615, 616, 667 Lucerne, 264 Ludwig, 738 Lupines, 90 _Lychnis_, 282 _chalcedonica_, 161 _diurna_, 238, 578 _preslii_, 578 _vespertina_, 238, 281, 585 _Lycium_, 455 _Lycopersicum_, 655 _grandifolium_, 654 _latifolium_ (see _L. grandifolium_). _solanopsis_, 854, 656 _validum_ (see _L. solanopsis_). Lyell, 1, 710 _Lysimachia vulgaris_, 684 M MacDougal, D.T., 62, 575, 590 Macfarlane, 56, 255, 268 _Madia elegans_, 779 _Magnolia_, 355, 366, 428, 674, 675 _obovata_, 355, 669 _Magnus_, 228 _Mahonia aquifolia_, 270 Maize, 134, 775 "Cuzco," 152 European, 206 "Gracillima," 152 "Horse-dent," 152 "Quarantino," 118 Mallow, 663, 684 _Malva crispa_, 684 Maples, laciniate, 615 Marchant, 592 Marigold, 131, 158 corn, 729 field, 503, 505, 508 garden, 503 Japanese, 490, 494, 495 Marsh-marigold, 331 Martinet, 80 Measart, 434 Masters, 228, 370, 372 _Matricaria Chamomilla_, 130 _Chamomilla discoidea_, 156 Matricaria discoidea, D.C., 157 May-thorn, red, 196 _Medicago media_, 264 _falcata_, 264 _Melanium_, 39 Melons, 118 Mendel, 6, 210, 294, 296, 306, 308 Mendel's law, 276, 293, 294, 298, 299, 300, 301, 307, 612, 613, 616, 716 Mendelism, 307 Mentha, 52 _Mercurialis annua_, 420 _annua laciniata_, 592 Mercury, 420, 422, 425, 820 Methods of investigation, 21 Metzger, 205, 206 Milde, 38 Milfoil, 441 Millardet, 266 Miller, 611 Millet, 105 _Mimulus_, 151 _quinquevulnerus_, 725 _Mimusops_, 697 Miocene period, 698 Miquel, 83 _Mirabilis_, 241 _Jalappa_, 322 Mirbel, 615 _Monardella macrantha_, 444 Monstrosities, 400, 401, 445, 446, 447 Monkey-flower, 725 Monocotyledons ancestry of, 1, 5 regression in, 630 _Monotropa_, 222, 661 Morphologic units, 145, 152 Monstrosities, 818 Morgan on mutation-theory, 9 Morren, 244, 762 Mountain-ash, 342 Muller, Fritz, 775, 776, 780 Multiplication, vegetative (see Asexual propagation) Munting, Abraham, 164, 165, 490, 762 Munting's drawings, 512 Murr, 158, 236 _Muscari comosam_, 134 Museum d'Histoire Naturelle, Paris, 522 Mutability vs. fluctuating variability, 568 Mutation, 659, 674, 677, 685, 686, 694, 713, 716, 825 absence of intermediate steps in, 474, 480 conditions for observing, 601 decided within the seed, 28 definition of, 7 easily observed, 30 experimental, 688 few observations of, 8 fluctuation vs., 7, 16, 719 influence of on variability, 335 iterative nature of, 476, , 703 laws of, 556, 558, 560, 562, 564, 566, 568, 570 limited in time, 29 observation of, 16 in _Oenothera_, 521, 525, 690 oldest known, 609 oldest recorded, 22 periodic, 690, 692, 694 perodicity of, 519 progressive, 307 repetition of, 476 in _Saponaria calabrica_, 612 simultaneous, 614 in tomato, 655 Mutations, 141, 275, 280, 445, 449, 573, 608, 620, 626, 678, 685, 686, 701, 704, 712, 713, 716, 800 artificial, 402 chance for useful, 598 defined, 191 frequency of, 597 in garden-flowers, 488 in horticulture, 604, 706 latent, 703 mode of appearance, 517 numerical proportion of, 475 original production of, 702 peloric, 707 periodic, 686, 705 progressive, 704 retrograde, 704 stray, 704, 705, 706 synonyms of, 191 Mutation-period, 714 _Myosotis azorica_, 368 _Myrtus communis_, 684 N Nageli, 60, 439, 443, 448, 795 Nagelian principle, 448, 450, 451 Natural selection, 18, 119, 120, 445, 456, 682, 694, 703, 743, 744, 798-826 basis, 604 nature of, 6, 19 Naudin, 118 Nectarines, 137, 138, 226, 627 Nemec, 578 Neo-Lamarckians principle of, 8 Neo-Lamarckism 447 _Nepenthes_, 671, 672, 673, 674 Newton, 1, 732, 767 _Nicandra_, 152 _Nigella_, 134 Nightshade, 298 black, 282 Nourishment meaning of, 732 variability and 771 _Nuphar_, 268 Nutrition and growth, 720, 722 _Nymphaea_, 698 O Oats, 98, 100, 101, 105, 112, 113, 115, 119, 133, 452 "Early Angus," 115 "Early Fellow," 115 "Fine Fellow," 115 "Hopetown," 112 "Longfellow," 115 "Make-him-rich," 112 wild, 207, 803 Oak, 136, 239 _Oenothera_, 260, 262, 279, 700, 706, 708, 709 European species, source of, 575 mutation in, 521, 525, 585, 690, 708 new species of, 516-546 _albida_, 537, 553, 555, 563, 565, 573 _biennia_, 82, 205, 256, 257, 258; 259, 262, 263, 264, 521, 524, 527, 574, 575, 586, 587, 683, 690, 708 _biennis cruciata_, 22, 587 _brevistylis_, 263, 280, 526, 529, 530, 547, 563, 564, 565, 573, 574, 702, 706 _cruciata_, 575, 585, 586, 589, 590, 683 _elliptica_, 540, 545, 555, 562 _gigas_, 533, 534, 535, 536; 537, 553, 554, 563, 565, 566, 567, 573, 574, 702 _glauca_, 424 _hirtella_, 262 _laevifolia_, 526, 528, 529, 547, 563, 564, 573, 574, 701, 706 _lamarckiana_, 17, 262, 262, 522, 523, 527, 528, 529,, 533, 574, 575, 586, 690, 699 pollination of, 524 _lata_, 540, 541, 542, 549, 550, 551, 552, 555, 559, 563, 566, 573, 574, 702 _leptocarpa_, 540 _muricata_, 256, 257, 258, 259, 262, 263, 264, 513, 575, 690 pollination of, 524 _nanella_, 526, 531, 549, 50, 551, 552, 555, 563, 564, 565, 566, 703 _oblonga_, 537, 538, 552, 555, 563, 565, 566, 572 _rubrinervis_, 533, 534, 536, 537, 550, 551, 552, 555, 563, 565, 568, 573, 574 _scintillans_, 540, 543, 553, 555, 563, 566, 573, 574 mutability of, 544 _semilata_, 540 _suaveolens_, 521 _Oleander_, 684 _Onagra_, 262, 708, 709 Onions, wild, 684 _Ononis repens_, 577 Orange, 90, 133, 134 Orchids, 631 Origin of species (Darwin), 109 _Orobanche_, 220 _Othonna crassifolia_, 442 Otin, 618 Oviedo, 89 P _Paeonia corallina leiocarpa_, 126 Paillat, 618 Pangenes, 306 Pangenesis, 306, 689 _Panicum_, 105 Pansies, 640 Pansy, 118, 121 _Papaver alpinum_, 139 _bracteatum_, 661 _bracteatum monopetalum_, 661 _commutatum_, 357 _dubium glabrum_, 126 hybridism, 662 _somniferum Danebrog, 162 _somniferum monstruosum_, 371 _somniferum polycephalum_, Parris, 754 Parsley crisped, 158, 181 Parsnip, water, 457 Pea-family, 344 Peach, 138, 226, 240 Peach-almond, 769 Pears, 79, 90, 134, 147, 152, 203, 283 Pearson, Karl, 716 Peas, sugar, 135, 158 _Pedicularis_, 410 _palustris_, 410 Pedigree-culture, 109 experimental, 547 _Pelargonium_, 272, 355 Peloria, definition of, 164 Peloric toad-flax first record of, 466 origin of, 459, 464, 472 sterility of, 467 Pelorism _Antirrhinum majus_ (see snapdragon) _Digitalis purpurea_, 482 _Gloxinia_, 484, 485 labiates, 486 _Laburnum_, 485 _Lamium_, 486. _Linaria_, see Toad-flax _Linaria dalmatica_, 482 _Linaria vulgaris_, 464 orchids, 479, 486, 487 _Salvia_, 486 _Scrophularia nodosa_, 486 snapdragon, 481 toad-flax, 459-487 _Tropaeolum majus_, 485 _Uropedium Lindenii_, 487 wild sage, 486 _Peltaria alliacea_, 663 Pennywort, marsh, 668 Penzig, 638 Periodicity, law of, 365, 368, 721, 722 Periods, mutative, 706, 708 Periwinkles, 322 Persicaria, water, 433, 434, 435, 643 Petalomany, 330 Petunia, 491, 626 _Phacelia_, 420, 422, 820 _Phaseolus lunatus_, 592 _multiflorus_, 202 _nanus_, 202 _Phleum alpinum_, 696 _Phlox_, 232 _drummondi_, 161 _Phyllonoma ruscifolia_, 676 Physiologic units, 144, 153, 249 _Picris hieraoioides_, 411 Pimpernel, scarlet, 162 Pinacothec, Munich, 164 Pine, 368, 804 Pine-apples, 90, 134 Pinks, 178 _Pinus sylvestris_, 368 Pistillody in poppies, 369, 370, 372 Pitcher-plants, 671 Plankton, 711 _Plantago_, 53 lanceolata_, 520, 671, 684 Plantain, 684 Plater, 610 Plum, 79, 134, 789 beach, 58 Japanese, 58 purple-leaved, 619 _Plusia_, 204 _Poa alpina vivipara_, 684 _Podocarpus koraiana_, 169 _Polemonium coeruleum_, 282 _coeruleum album_, 200 _dissectum_, 161, 202 _Polygala_, 242 _Polygonum amphibium_, 432 var. _natans_ Moench, 433, 434 var. _terrestris_ Wench, 433, 434 _Convolvulus_, 419, 424 _viviparum_, 684 Polymorphy, 188 Pomegranate, 90 Pond-lily, yellow, 268 Poplar, fastigiate, 623, 624 Italian, 623 _Populus italica_, 622 _nigra_, 624 Poppy, 146, 151, 152, 163, 165, 241, 356, 640, 723 "Danebrog," 283, 291 garden, 661 "Mephisto," 283, 291 opium, 89, 189, 195, 198, 282, 291, 369, 371, 373, 379, 383, 391, 405, 406, 420, 452, 720, 789 pistillody in, 369 pistilloid, 508 polycephalous, 405 Potatoes, 765, 810 _Potentilla Tormentilla_, 52 Pre-Linnean attitude, 2 Primrose, 268, 372, 410 evening (see evening-primrose). _Primula acaulis_, 52, 632 _elatior_, 52, 633, 635 _grandiflora_, 268 _imperialis_, 697 _japonica_, 410 _officinalis_, 52, 268, 633, 635 _variabilis_, 268 _veris_, 52, 633, 634 Prodromus (De Candolle) 370 Progression, 430, 705, 774, 775, 777, 779, 805 in evolution, 630 Propagation asexual, 745, 751, 766, 767, 770, 774, 777 sexual, 745, 777 vegetative (see asexual) Proskowetz, Em. von, 70 Prototype definition of, 170 _Prunus_, 52 _cerasifera_, 619 _Mahaleb_, 617 _nana_, 612 _maritima_, 59 _Padus_, 617 _Pissardi_, 619 variation in, 56 _Pyrethrum roseum_, 511 _Pyrola_, 222, 661 Q Quartile, 736, 737, 767 _Quercus pedunculata fastigata_, 596 Quetelet's law, 463, 716, 717, 725, 730, 734, 738, 748, 753, 759, 767, 775, 779, 780, 806 R Races, inconstancy of improved, 770-797 Raciborsky, 682 Radishes, 325, 806 Ragwort, tansy, 157 Raisins, 134 Rameses, 697 _Ranunculus_, 331 _acris_, 331 _arvensis_, 282 _arvensis inermis_, 125 _asiaticus_, ,241 _bulbosus_, 357, 410, 740 Ra-n-Woser, King, 104 _Raphanus Raphanistrum_, 202, 424,520 _caudatus_, 202 Rasor, John, 588, 589 Raspberry, 268, 768 "Phenomenal," 268 "Primus," 269 Siberian, 269 Ratzeburg, 467 Raunkiaer on variation in _Taraxacum_, 60 Recessive character, 280 Sports, 191, 715, 689 bud, 427 S Sprenger, 610, 611 Stability, 155 Stahl, 611 _Stellaria Holostea apetala_, 585 Stocks, 146, 322, 328, 329, 332, 334, 336, 338, 432 Stock "Brompton," 329 chamois-colored, 198 "Queen," 324 white, 160 Stork's-bill, white hemlock, 161 Strasburger, 196, 448 Strawberry, 158, 266, 342 "Gaillon," 135 "Giant of Zuidwijk," 614 one-leaved, 164, 596, 666 white, 158, 165 Striped flowers, 309, 374, 431, 606, 607 races, types of, 328 Struggle for life, 674, 571, 682, 702, 799, 803, 824, 825 St. Johnswort, 725 St. Sebastian, 164 Sub-species (see also Elementary species), 224, 225 Sugar-beets (see Beets, sugar) Sugar-cane, 731, 752 "Black Manilla," 753 "Cheribon," 753, 755, 756 "Chunnic," 753 "Hawaii," 755, 756 seeds of, 754 "White Manilla," 752 Sundew, 268 Sunflower, 410, 425, 820 Sweet-flag, 222 Sweet-pea, 160, 776 Sweet William, 163, 282, 322, 648 twisted variety, 408, 648 Syncotyls, 417, 424 _Syringa vulgaris axurea plena_, 763 Systematic species, 12, 64, 101, 128 nature of, 54, 62 Systematic units, 61, 91 T _Tagetes africana_, 510 _signata_, 612 "Talavera de Bellevue," 97 _Tanacetum vulgare_, 131, 132, 236 Tansy, 131, 132, 236 _Taraxacum_, 125, 126 officinale, 59, 411 _Tares_, 105 _Taxus_, 136 _baccata_, 169 _baccata fastigiata_, 170, 618 _minor_, 169 Teasels, 402, 642, 645, 674, 675 twisted, 405, 412, 446, 447, 643, 646, 647, 648, 819 _Tetragonia expansa_, 162 Theatre d'Agriculture, 72 Thibault, 618 Thomson, Sir William (see Kelvin, Lord) Thorn-apples, 139, 142, 143, 145, 238, 283, 300, 452 thornless, 234 Thorn-broom, 457 _Thrincia hirta_, 411 Thuret, 38, 47, 49 Thyme, white creeping, 201 _Thymus Serphyllum album_, 201 _vulgaris_, 577 _Tilia parvifolia_, 355, 669 Toad-flax, 267, 282, 707 cross pollination of, 471 experiment with, described, 468 invisible dimorphous state of, 470, 471, 478 latent tendency to mutation in, 479 peloric, see Peloric toad flax sterility of mutants, 477 unusual pelorism, 486 Tomato, 653 "Acme," 656, 657 "Mikado," 654 mutation of, 655 upright, 654 "Washington," 657 Tournefort author of genera, 32 Tracy, W.W. 592 Trees, genealogic, 707, 708 Tricotyls, 416, 419, 420 _Trifolium incarnatum_, 352 _Triticum dicoccum_, 105 _Tropaeolum_, 193, 668 _majus_, pelorism of, 485 "True Exercises with Plants" (hunting), 490 Tulips, 149, 178, 274, 322 black, 620 Turnip, 244, 621 Twisted stems, 402, 403, 405, 413 Twisted varieties atavists of, 406 U _Ulex europaeus_, 140, 217 _Ulmus pedunculata_, 615 _pedunculata urticaefolia_, 615 Umbellifers, 457 _Umbilicus_, 669 Unger, 105 Unit-characters, 249, 261, 306, 307, 313, 658, 689, 715, 716 Urban, 265 _Uropedium lindenii_, 487 Utility, 685, 724 Utricularia, 672 V _Vaccinium Myrtillus_, 577 Valerian, 402, 409, 648 twisted, 403 _Valeriana officinalis_, 402 _Vallisneria_, 684. Van den Berg, 625 Van de Water, 614 Van Mons, 76, 77, 78, 806 Variability (see also Fluctuation ), 188, 190, 191 analogous, 244 apple, 75 asexual, 320 correlative, 142, 143, 148, 167 cultivated plants, 66 embryonic, 770, 771, 814 ever-recurring, 190 fluctuating (see also individual), 62, 142, 190, 233, 375, 416, 454, 698, 759, 762, 765, 766, 767, 770, 771, 789, 805, 814 fluctuating vs. mutability 569 homologous, 244 individual (see also fluctuating), 190, 716, 718, 746, 749, 770, 814 influence of mutation on, 335 kinds of, 715 nutrition and, 390, 391, 719, 771 parallel, 243 partial, 440, 444, 718, 746, 748, 753, 814, 816 repeated, 242 restricted, 598 sectional, 317 sexual, 320 sources of, 758 Variation bud, 176, 178, 180, 284, 317, 318, 321, 338, 427, 750 definition of, 188 partial, 788, 789 seed, 750 spontaneous, 191 use of term, 189 Variegation, 426, 427 Varietal marks, origin of, 275 Varieties, 84, 95, 126, 127, 128, 129, 132, 142 broom-like, 618, 624 constancy of, 532 constant, 135 crosses of species with, 247, 277, 278, 281 elementary species vs. 459 ever-sporting, 178, 309, 310, 311, 312, 313, 321, 324, 328, 329, 332, 333, 334, 350, 358, 365, 368, 372, 399, 413, 420, 430, 431, 432, 434, 445, 606, 607, 628, 740, 789, 790, 795 fasciated (see Fasciated stems). groups of, 606 horticultural, 607, 609 hybrid, 122, 190, 608 hybrids of, 210, 254, 255 inconstant, 135, 154; 155, 161 mutation of, 141 negative (retrogressive), 131, 132, 134, 224, 226, 238, 245, 277 positive, 131, 132, 134, 224, 238, 245 pure, 122, 190 retrograde, 14, 15, 16, 95, 121, 208, 430, 435, 606, 607 retrogressive (see negative). seed, 122 single, 191 spontaneous crosses, 209 sporting (see inconstant) stability of, 207 sterile, 622 types of, 142 variable, 606 vegetative, 122 weeping, 617 Variety, 130 definition of, 11, 12 elementary species vs. 141, 152, 154, 224, 243, 247, 251 origin of, 141, 152, 224 use of term, 189, 435 Variety-testing, 95, 97, 116, 119, 743, 799, 825 Varro, 106 Veitch & Sons, 272 Venus' looking-glass, 367 Verlot, 186, 612 Vernon, 132 _Vernonia cinerea_, 450 _Veronica longifolia_, 282, 284 _scutellata_, 139 _spicata nitens_, 126 _Viburnum Opulus_, 134, 239 Vicinism, 185, 188, 203, 205, 206, 213, 214, 776 definition of, 188, 192, 606 Vicinist, 199, 201 _Vicoa aurioulata_, 450 _Victoria regia_, 668 Villars on _Draba verna_, 49 Vilmorin, 570, 607, 612, 622, 661, 662, 773, 775, 776; 792, 795, 796, 797, 806, 807, 810, 813, 818, 820 Vilmorin, Louis de, 72, 92, 93, 97, 108, 109, 110, 114, 185, 818 Vilmorin, Messrs., 322 _Vinca_, 242, 490 _minor_, 322 Vine, parsley-leaved, 179 _Viola_, 126, 546, 547, 692 _agrestis_, 45 _alpestris_, 40 _altaica_, 39 _anopetala_, 44 _arvensis_, 39, 40, 41, 44 _curtisepala_, 45 _striolata_, 45 _aurobadia_, 44 _caloarata_, 39 _cornuta_, 39, 281 _lutea_, 38 _lutescens_, 44 _nemausensis_, 45 _ornatissima_, 44 _palescens_, 45 _patens_, 45 _roseola_, 44 _segetatis_, 45 _stenochila_, 41 _tricolor_, 38, 40, 41, 44, 46 _ammotropha_, 41 _coniophila_, 41 _genuina_, 42 _versicolor_, 42 Violets, 63, 232, 233, 490 Violet, dame's, 322, 323, 411 long-spurred, 281 Virgil, 105, 106, 108 _Viscaria oculata_, 4, 648, 821 twisted variety, 408 _Vitis_, 52 Volckamer, 228 Von Lochow, 821, 822, 822 Von Rumker, 94 Von Wettstein, 448, 805 Vrolik, 164, 483 W "Waare Oeffeninge der Planten" (Munting), 490 Wallace, 5, 7, 8, 30, 205 Wall-flower, 370, 371 Walnut, 243, 766 cut-leaved, 616 one-bladed, 666 Water-lilies, 668 Weber, 228 Weeping-willow, 180 crisped, 181 Weigelias, 740 _Wellingtonia_, 618 Wheat, 96, 98, 105, 113, 119, 283, 810, 823 bearded, 98 "Blue-stem," 117 "Galland," 100, 207 "Hopetown," 112, 112 "Hunter's," 111, 112 "Minnesota No. 169," 117 "Mungoswell's," 110, 111 "Pedigree," 109 "Pringle's," 114 "Rivett's bearded," 207 "Sheriff's bearded red," 114 "Sheriff's bearded white," 114 "White Hunter's," 112 Wheat-ear carnation, 227 White, C.A., 656, 657 White varieties, 577 Whitlow-grasses, 63, 118, 119 Whorls, ternate, 684 Wild sage (see Salvia) Willdenow, 468, 666, 667 Williamson, 491 Willows, 135, 267 Willow weeping (see Weeping-Willow) Willow-herb, 268, 269, 682 Wintercress, 427 Wintergreen, 661 Wittmack, 682 Wittrock, 38, 40, 41, 42, 43, 44, 45, 46 Wooton, E.O., 140 Wormseed, 638 X _Xanthium canadense_, 140 _commune_, 140, 152, 591 _commune Wootoni_, 22 Wootoni, 140, 152, 591 Y Yarrow, 131, 132 Yew, 136, 169 pyramidal, 618 Z _Zea Mays cryptosperma_, 641 _tunicata_, 641 _Zinnia_, 490 Zioberg, 466 Zocher & Co., 230 
27600	----	Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 27600-h.htm or 27600-h.zip: (http://www.gutenberg.net/dirs/2/7/6/0/27600/27600-h/27600-h.htm) or (http://www.gutenberg.net/dirs/2/7/6/0/27600/27600-h.zip) Transcriber's note A few typographical errors have been corrected: they are listed at the end of the text. ZOONOMIA; OR, THE LAWS OF ORGANIC LIFE. VOL. II. _By ERASMUS DARWIN, M.D. F.R.S._ AUTHOR OF THE BOTANIC GARDEN. Principiò coelum, ac terras, camposque liquentes, Lucentemque globum lunæ, titaniaque astra, Spiritus intùs alit, totamque infusa per artus Mens agitat molem, et magno se corpore miscet.--VIRG. Æn. vi. Earth, on whose lap a thousand nations tread, And Ocean, brooding his prolific bed, Night's changeful orb, blue pole, and silvery zones, Where other worlds encircle other suns, One Mind inhabits, one diffusive Soul Wields the large limbs, and mingles with the whole. London: Printed for. J. Johnson, in St. Paul's Church-Yard. 1796. Entered at Stationers' Hall. ZOONOMIA; OR, THE LAWS OF ORGANIC LIFE. PART II. CONTAINING A CATALOGUE OF DISEASES DISTRIBUTED INTO NATURAL CLASSES ACCORDING TO THEIR PROXIMATE CAUSES, WITH THEIR SUBSEQUENT ORDERS, GENERA, AND SPECIES, AND WITH THEIR METHODS OF CURE. * * * * * Hæc, ut potero, explicabo; nec tamen, quasi Pythius Apollo, certa ut sint et fixa, quæ dixero; sed ut Homunculus unus e multis probabiliora conjecturâ sequens.--CIC. TUSC. DISP. l. 1. 9. * * * * * PREFACE. All diseases originate in the exuberance, deficiency, or retrograde action, of the faculties of the sensorium, as their proximate cause; and consist in the disordered motions of the fibres of the body, as the proximate effect of the exertions of those disordered faculties. The sensorium possesses four distinct powers, or faculties, which are occasionally exerted, and produce all the motions of the fibrous parts of the body; these are the faculties of producing fibrous motions in consequence of irritation which is excited by external bodies; in consequence of sensation which is excited by pleasure or pain; in consequence of volition which is excited by desire or aversion; and in consequence of association which is excited by other fibrous motions. We are hence supplied with four natural classes of diseases derived from their proximate causes; which we shall term those of irritation, those of sensation, those of volition, and those of association. In the subsequent classification of diseases I have not adhered to the methods of any of those, who have preceded me; the principal of whom are the great names of Sauvages and Cullen; but have nevertheless availed myself, as much as I could, of their definitions and distinctions. The essential characteristic of a disease consists in its proximate cause, as is well observed by Doctor Cullen, in his Nosologia Methodica, T. ii. Prolegom. p. xxix. Similitudo quidem morborum in similitudine causæ eorum proximæ, qualiscunque sit, reverâ consistit. I have taken the proximate cause for the classic character. The characters of the orders are taken from the excess, or deficiency, or retrograde action, or other properties of the proximate cause. The genus is generally derived from the proximate effect. And the species generally from the locality of the disease in the system. Many species in this system are termed genera in the systems of other writers; and the species of those writers are in consequence here termed varieties. Thus in Dr. Cullen's Nosologia the variola or small-pox is termed a genus, and the distinct and confluent kinds are termed species. But as the infection from the distinct kind frequently produces the confluent kind, and that of the confluent kind frequently produces the distinct; it would seem more analogous to botanical arrangement, which these nosologists profess to imitate, to call the distinct and confluent small-pox varieties than species. Because the species of plants in botanical systems propagate others similar to themselves; which does not uniformly occur in such vegetable productions as are termed varieties. In some other genera of nosologists the species have no analogy to each other, either in respect to their proximate cause, or to their proximate effect, though they may he somewhat similar in less essential properties; thus the thin and saline discharge from the nostrils on going into the cold air of a frosty morning, which is owing to the deficient action of the absorbent vessels of the nostrils, is one species; and the viscid mucus discharged from the secerning vessels of the same membrane, when inflamed, is another species of the same genus, Catarrhus. Which bear no analogy either in respect to their immediate cause or to their immediate effect. The uses of the method here offered to the public of classing diseases according to their proximate causes are, first, more distinctly to understand their nature by comparing their essential properties. Secondly, to facilitate the knowledge of the methods of cure; since in natural classification of diseases the species of each genus, and indeed the genera of each order, a few perhaps excepted, require the same general medical treatment. And lastly, to discover the nature and the name of any disease previously unknown to the physician; which I am persuaded will be more readily and more certainly done by this natural system, than by the artificial classifications already published. The common names of diseases are not well adapted to any kind of classification, and least of all to this from their proximate causes. Some of their names in common language are taken from the remote cause, as worms, stone of the bladder; others from the remote effect, as diarrhoea, salivation, hydrocephalus; others from some accidental symptom of the disease, as tooth-ach, head-ach, heart-burn; in which the pain is only a concomitant circumstance of the excess or deficiency of fibrous actions, and not the cause of them. Others again are taken from the deformity occasioned in consequence of the unnatural fibrous motions, which constitute diseases, as tumours, eruptions, extenuations; all these therefore improperly give names to diseases; and some difficulty is thus occasioned to the reader in endeavouring to discover to what class such disorders belong. Another difficulty attending the names of diseases is, that one name frequently includes more than one disease, either existing at the same time or in succession. Thus the pain of the bowels from worms is caused by the increased action of the membrane from the stimulus of those animals; but the convulsions, which sometimes succeed these pains in children, are caused by the consequent volition, and belong to another class. To discover under what class any disease should be arranged, we must first investigate the proximate cause; thus the pain of the tooth-ach is not the cause of any diseased motions, but the effect; the tooth-ach therefore does not belong to the class of Sensation. As the pain is caused by increased or decreased action of the membranes of the tooth, and these actions are owing to the increase or decrease of irritation, the disease is to be placed in the class of irritation. To discover the order it must be inquired, whether the pain be owing to increased or defective motion of the pained membrane; which is known by the concomitant heat or coldness of the part. In tooth-ach without inflammation there is generally a coldness attends the cheek in its vicinity; as may be perceived by the hand of the patient himself, compared with the opposite cheek. Hence odontalgia is found to belong to the order of decreased irritation. The genus and species must be found by inspecting the synopsis of the second order of the class of Irritation. See Class I. 2. 4. 12. This may be further elucidated by considering the natural operation of parturition; the pain is occasioned by the increased action or distention of the vessels of the uterus, in consequence of the stimulus of the fetus; and is therefore caused by increased irritation; but the action of the abdominal muscles in its exclusion are caused by the pain, and belong to the class of increased sensation. See Class II. 1. 1. 12. Hence the difficulty of determining, under what class of diseases parturition should be arranged, consists in there being two kinds of diseased actions comprehended under one word; which have each their different proximate cause. In Sect. XXXIX. 8. 4. and in Class II. 1. 1. 1. we have endeavoured to give names to four links of animal causation, which conveniently apply to the classification of diseases; thus in common nictitation, or winking with the eyes without our attention to it, the increased irritation is the proximate cause; the stimulus of the air on the dry cornea is the remote cause; the closing of the eyelid is the proximate effect; and the diffusion of tears over the eye-ball is the remote effect. In some cases two more links of causation may be introduced; one of them may be termed the pre-remote cause; as the warmth or motion of the atmosphere, which causes greater exhalation from the cornea. And the other the post-remote effect; as the renewed pellucidity of the cornea; and thus six links of causation may be expressed in words. But if amid these remote links of animal causation any of the four powers or faculties of the sensorium be introduced, the reasoning is not just according to the method here proposed; for these powers of the sensorium are always the proximate causes of the contractions of animal fibres; and therefore in true language cannot be termed their remote causes. From this criterion it may always be determined, whether more diseases than one are comprehended under one name; a circumstance which has much impeded the investigation of the causes, and cures of diseases. Thus the term fever, is generally given to a collection of morbid symptoms; which are indeed so many distinct diseases, that sometimes appear together, and sometimes separately; hence it has no determinate meaning, except it signifies simply a quick pulse, which continues for some hours; in which sense it is here used. In naming diseases I have endeavoured to avoid the affectation of making new compound Greek words, where others equally expressive could be procured: as a short periphrasis is easier to be understood, and less burthensome to the memory. In the Methodus Medendi, which is marked by M.M. at the end of many of the species of diseases, the words incitantia, sorbentia, torpentia, &c. refer to the subsequent articles of the Materia Medica, explaining the operations of medicines. The remote causes of many diseases, their periods, and many circumstances concerning them, are treated of in the preceding volume; the descriptions of many of them, which I have omitted for the sake of brevity, may be seen in the Nosologia Methodica of Sauvages, and in the Synopsis Nosologiæ of Dr. Cullen, and in the authors to which they refer. In this arduous undertaking the author solicits the candour of the critical reader; as he cannot but foresee, that many errors will be discovered, many additional species will require to be inserted; and others to be transplanted, or erased. If he could expend another forty years in the practice of medicine, he makes no doubt, but that he could bring this work nearer perfection, and thence render it more worthy the attention of philosophers.----As it is, he is induced to hope, that some advantages will be derived from it to the science of medicine, and consequent utility to the public, and leaves the completion of his plan to the industry of future generations. DERBY, _Jan._ 1, 1796. * * * * * ZOONOMIA. PART II. * * * * * CLASSES OF DISEASES. * * * * * I. DISEASES OF IRRITATION. II. DISEASES OF SENSATION. III. DISEASES OF VOLITION. IV. DISEASES OF ASSOCIATION. * * * * * _The Orders and Genera of the First Class of Diseases._ * * * * * CLASS I. DISEASES OF IRRITATION. ORDO I. _Increased Irritation._ GENERA. 1. With increased actions of the sanguiferous system. 2. With increased actions of the secerning system. 3. With increased actions of the absorbent system. 4. With increased actions of other cavities and membranes. 5. With increased actions of the organs of sense. ORDO II. _Decreased Irritation._ GENERA. 1. With decreased actions of the sanguiferous system. 2. With decreased actions of the secerning system. 3. With decreased actions of the absorbent system. 4. With decreased actions of other cavities and membranes. 5. With decreased actions of the organs of sense. ORDO III. _Retrograde Irritative Motions._ GENERA. 1. Of the alimentary canal. 2. Of the absorbent system. 3. Of the sanguiferous system. * * * * * _The Orders, Genera, and Species, of the First Class of Diseases._ * * * * * CLASS I. DISEASES OF IRRITATION. ORDO I. _Increased Irritation._ GENUS I. _With Increased Actions of the Sanguiferous System._ SPECIES. 1. _Febris irritativa._ Irritative fever. 2. _Ebrietas._ Drunkenness. 3. _Hæmorrhagia arteriosa._ Arterial hæmorrhage. 4. _Hæmoptoe arteriosa._ Spitting of arterial blood. 5. _Hæmorrhagia narium._ Bleeding from the nose. GENUS II. _With Increased Actions of the Secerning System._ SPECIES. 1. _Calor febrilis._ Febrile heat. 2. _Rubor febrilis._ Febrile redness. 3. _Sudor calidus._ Warm sweat. ---- _febrilis._ Sweat in fevers. ---- _a labore._ ---- from exercise. ---- _ab igne._ ---- from fire. ---- _a medicamentis._ ---- from medicines. 4. _Urina uberior colorata._ Copious coloured urine. 5. _Diarrhoea calida._ Warm diarrhoea. ---- _febrilis._ ---- from fever. ---- _crapulosa._ ---- from indigestion. ---- _infantum._ ---- of infants. 6. _Salivatio calida._ ---- salivation. 7. _Catarrhus calidus._ ---- catarrh. 8. _Expectoratio calida._ ---- expectoration. 9. _Exsudatio pone aures._ Discharge behind the ears. 10. _Gonorrhoea calida._ Warm gonorrhoea. 11. _Fluor albus calidus._ ---- fluor albus. 12. _Hæmorrhois alba._ White piles. 13. _Serum e visicatorio._ Discharge from a blister. 14. _Perspiratio foetida._ Fetid perspiration. 15. _Crines novi._ New hairs. GENUS III. _With increased Actions of the Absorbent System._ SPECIES. 1. _Lingua arida._ Dry tongue. 2. _Fauces aridæ._ Dry throat. 3. _Nares aridi._ Dry nostrils. 4. _Expectoratio solida._ Solid expectoration. 5. _Constipatio alvi._ Costiveness. 6. _Cutis arida._ Dry skin. 7. _Urina parcior colorata._ Diminished coloured urine. 8. _Calculus felleus et icterus._ Gall-stone and jaundice. 9. ---- _renis._ Stone of the kidney. 10. ---- _vesicæ._ Stone of the bladder. 11. ---- _arthriticus._ Gout-stone. 12. _Rheumatismus chronicus._ Chronic rheumatism. 13. _Cicatrix vulnerum._ Healing of ulcers. 14. _Corneæ obfuscatio._ Scar on the cornea. GENUS IV. _With increased Actions of other Cavities and Membranes._ SPECIES. 1. _Nictitatio irritativa._ Irritative nictitation. 2. _Deglutitio irritativa._ Irritative deglutition. 3. _Respiratio et tussis._ Respiration and cough. 4. _Exclusio bilis._ Exclusion of the bile. 5. _Dentitio._ Toothing. 6. _Priapismus._ Priapism. 7. _Distensio mamularum._ Distention of the nipples. 8. _Descensus uteri._ Descent of the uterus. 9. _Prolapsus ani._ Descent of the rectum. 10. _Lumbricus._ Round worm. 11. _Tænia._ Tape-worm. 12. _Ascarides._ Thread-worms. 13. _Dracunculus._ Guinea-worm. 14. _Morpiones._ Crab-lice. 15. _Pediculi._ Lice. GENUS V. _With increased Actions of the Organs of Sense._ SPECIES. 1. _Visus acrior._ Acuter sight. 2. _Auditus acrior._ ---- hearing. 3. _Olfactus acrior._ ---- smell. 4. _Gustus acrior._ ---- taste. 5. _Tactus acrior._ ---- touch. 6. _Sensus caloris acrior._ ---- sense of heat. 7. ---- _extensionis acrior._ ---- sense of extension. 8. _Titillatio._ Tickling. 9. _Pruritus._ Itching. 10. _Dolor urens._ Smarting. 11. _Consternatio._ Surprise. ORDO II. _Decreased Irritation._ GENUS I. _With decreased Actions of the Sanguiferous System._ SPECIES. 1. _Febris inirritativa._ Inirritative fever. 2. _Paresis inirritativa._ ---- debility. 3. _Somnus interruptus._ Interrupted sleep. 4. _Syncope._ Fainting. 5. _Hæmorrhagia venosa._ Venous hæmorrhage. 6. _Hæmorrhois cruenta._ Bleeding piles. 7. _Hæmorrhagia renum._ ---- from the kidneys. 8. ---- _hepatis._ ---- from the liver. 9. _Hæmoptoe venosa._ Spitting of venous blood. 10. _Palpitatio cordis._ Palpitation of the heart. 11. _Menorrhagia._ Exuberant menstruation. 12. _Dysmenorrhagia._ Deficient menstruation. 13. _Lochia nimia._ Too great lochia. 14. _Abortio spontanea._ Spontaneous abortion. 15. _Scorbutus._ Scurvy. 16. _Vibices._ Extravasations of blood. 17. _Petechiæ._ Purple spots. GENUS II. _With decreased Actions of the Secerning System._ SPECIES. 1. _Frigus febrile._ Coldness in fevers. ---- _chronicum._ ---- permanent. 2. _Pallor fugitivus._ Paleness fugitive. ---- _permanens._ ---- permanent. 3. _Pus parcius._ Diminished pus. 4. _Mucus parcior._ Diminished mucus. 5. _Urina parcior pallida._ Pale diminished urine. 6. _Torpor hepaticus._ Torpor of the liver. 7. _Torpor pancreatis._ Torpor of the pancreas. 8. _Torpor renis._ Torpor of the kidney. 9. _Punctæ mucosæ vultus._ Mucous spots on the face. 10. _Maculæ cutis fulvæ._ Tawny blots on the skin. 11. _Canities._ Grey hairs. 12. _Callus._ Callus. 13. _Cataracta._ Cataract. 14. _Innutritio ossium._ Innutrition of the bones. 15. _Rachitis._ Rickets. 16. _Spina distortio._ Distortion of the spine. 17. _Claudicatio coxaria._ Lameness of the hip. 18. _Spina protuberans._ Protuberant spine. 19. _Spina bifida._ Divided spine. 20. _Defectus palati._ Defect of the palate. GENUS III. _With decreased Actions of the Absorbent System._ SPECIES. 1. _Mucus faucium frigidus._ Cold mucus from the throat. 2. _Sudor frigidus._ ---- sweat. 3. _Catarrhus frigidus._ ---- catarrh. 4. _Expectoratio frigida._ ---- expectoration. 5. _Urina uberior pallida._ Copious pale urine. 6. _Diarrhoea frigida._ Cold diarrhoea. 7. _Fluor albus frigidus._ ---- fluor albus. 8. _Gonorrhoea frigida._ ---- gonorrhoea. 9. _Hepatis tumor._ Swelling of the liver. 10. _Chlorosis._ Green sickness. 11. _Hydrocele._ Dropsy of the vagina testis. 12. _Hydrocephalus internus._ ---- of the brain. 13. _Ascites._ ---- of the belly. 14. _Hydrothorax._ ---- of the chest. 15. _Hydrops ovarii._ ---- of the ovary. 16. _Anasarca pulmonum._ ---- of the lungs. 17. _Obesitas._ Corpulency. 18. _Splenis tumor._ Swelling of the spleen. 19. _Genu tumor albus._ White swelling of the knee. 20. _Bronchocele._ Swelled throat. 21. _Scrophula._ King's evil. 22. _Schirrus._ Schirrus. 23. ---- _recti._ ---- of the rectum. 24. ---- _urethræ._ ---- of the urethra. 25. ---- _oesophagi._ ---- of the throat. 26. _Lacteorum inirritabilitas._ Inirritability of the lacteals. 27. _Lymphaticorum inirritabilitas._ Inirritability of the lymphatics. GENUS IV. _With decreased Actions of other Cavities and Membranes._ SPECIES. 1. _Sitis calida._ Thirst warm. ---- _frigida._ ---- cold. 2. _Esuries._ Hunger. 3. _Nausea sicca._ Dry Nausea. 4. _Ægritudo ventriculi._ Sickness of stomach. 5. _Cardialgia._ Heart-burn. 6. _Arthritis ventriculi._ Gout of the stomach. 7. _Colica flatulenta._ Flatulent colic. 8. _Colica saturnina._ Colic from lead. 9. _Tympanitis._ Tympany. 10. _Hypochondriasis._ Hypochondriacism. 11. _Cephalæa frigida._ Cold head-ach. 12. _Odontalgia._ Tooth-ach. 13. _Otalgia._ Ear-ach. 14. _Pleurodyne chronica._ Chronical pain of the side. 15. _Sciatica frigida._ Cold sciatica. 16. _Lumbago frigida._ ---- lumbago. 17. _Hysteralgia frigida._ ---- pain of the uterus. 18. _Proctalgia frigida._ ---- pain of the rectum. 19. _Vesicæ felleæ inirritibilitas_ Inirritability of the gall-bladder _et icterus._ and jaundice. GENUS V. _With decreased Actions of the Organs of Sense._ SPECIES. 1. _Stultitia inirritabilis._ Folly from inirritability. 2. _Visus imminutus._ Impaired vision. 3. _Muscæ volitantes._ Dark moving specks. 4. _Strabismus._ Squinting. 5. _Amaurosis._ Palsy of the optic nerve. 6. _Auditus imminutus._ Impaired hearing. 7. _Olfactus imminutus._ ---- smell. 8. _Gustus imminutus._ ---- taste. 9. _Tactus imminutus._ ---- touch. 10. _Stupor._ Stupor. ORDO III. _Retrograde Irritative Motions._ GENUS I. _Of the Alimentary Canal._ SPECIES. 1. _Ruminatio._ Chewing the cud. 2. _Ructus._ Eructation. 3. _Apepsia._ Indigestion, water-qualm. 4. _Vomitus._ Vomiting. 5. _Cholera._ Cholera. 6. _Ileus._ Iliac passion. 7. _Globus hystericus._ Hysteric strangulation. 8. _Vomendi conamen inane._ Vain efforts to vomit. 9. _Borborigmus._ Gurgling of the bowels. 10. _Hysteria._ Hysteric disease. 11. _Hydrophobia._ Dread of water. GENUS II. _Of the Absorbent System._ SPECIES. 1. _Catarrhus lymphaticus._ Lymphatic catarrh. 2. _Salivatio lymphatica._ Lymphatic salivation. 3. _Nausea humida._ Moist nausea. 4. _Diarrhoea lymphatica._ Lymphatic flux. 5. _Diarrhoea chylifera._ Flux of chyle. 6. _Diabætes._ Diabetes. 7. _Sudor lymphaticus._ Lymphatic sweat. 8. _Sudor asthmaticus._ Asthmatic sweat. 9. _Translatio puris._ Translation of matter. 10. ---- _lactis._ ---- of milk. 11. ---- _urinæ._ ---- of urine. GENUS III. _Of the Sanguiferous System._ SPECIES. 1. _Capillarium motus retrogressus._ Retrograde motion of the capillaries. 2. _Palpitatio cordis._ Palpitation of the heart. 3. _Anhelatio spasmodica._ Spasmodic panting. * * * * * CLASS I. DISEASES OF IRRITATION. ORDO I. _Increased Irritation._ GENUS I. _With increased Actions of the Sanguiferous System._ The irritability of the whole, or of part, of our system is perpetually changing; these vicissitudes of irritability and of inirritability are believed to depend on the accumulation or exhaustion of the sensorial power, as their proximate cause; and on the difference of the present stimulus, and of that which we had previously been accustomed to, as their remote cause. Thus a smaller degree of heat produces pain and inflammation in our hands, after they have been for a time immersed in snow; which is owing to the accumulation of sensorial power in the moving fibres of the cutaneous vessels during their previous quiescence, when they were benumbed with cold. And we feel ourselves cold in the usual temperature of the atmosphere on coming out of a warm room; which is owing to the exhaustion of sensorial power in the moving fibres of the vessels of the skin by their previous increased activity, into which they were excited by unusual heat. Hence the cold fits of fever are the occasion of the succeeding hot ones; and the hot fits contribute to occasion in their turn the succeeding cold ones. And though the increase of stimulus, as of heat, exercise, or distention, will produce an increased action of the stimulated fibres; in the same manner as it is produced by the increased irritability which was occasioned by a previous defect of stimulus; yet as the excesses of irritation from the stimulus of external things are more easily avoided than the deficiencies of it; the diseases of this country, except those which are the consequences of drunkenness, or of immoderate exercise, more frequently begin with torpor than with orgasm; that is, with inactivity of some parts, or of the whole of the system, and consequent coldness, than with increased activity, and consequent heat. If the hot fit be the consequence of the cold one, it may be asked if they are proportionate to each other: it is probable that they are, where no part is destroyed by the cold fit, as in mortification or death. But we have no measure to distinguish this, except the time of their duration; whereas the extent of the torpor over a greater or less part of the system, which occasions the cold fit; or of the exertion which occasions the hot one; as well as the degree of such torpor or exertion, are perhaps more material than the time of their duration. Besides this some muscles are less liable to accumulate sensorial power during their torpor, than others, as the locomotive muscles compared with the capillary arteries; on all which accounts a long cold fit may often be followed by a short hot one. SPECIES. 1. _Febris irritativa._ Irritative fever. This is the synocha of some writers, it is attended with strong pulse without inflammation; and in this circumstance differs from the febris inirritativa of Class I. 2. 1. 1. which is attended with weak pulse without inflammation. The increased frequency of the pulsation of the heart and arteries constitutes fever; during the cold fit these pulsations are always weak, as the energy of action is then decreased throughout the whole system; and therefore the general arterial strength cannot be determined by the touch, till the cold part of the paroxysm ceases. This determination is sometimes attended with difficulty; as strong and weak are only comparative degrees of the greater or less resistance of the pulsation of the artery to the compression of the finger. But the greater or less frequency of the pulsations affords a collateral evidence in those cases, where the degree of strength is not very distinguishable, which may assist our judgment concerning it. Since a moderately strong pulse, when the patient is in a recumbent posture, and not hurried in mind, seldom exceeds 120 strokes in a minute; whereas a weak one often exceeds 130 in a recumbent posture, and 150 in an erect one, in those fevers, which are termed nervous or putrid. See Sect. XII. 1. 4. The increased frequency of the pulsation of the heart and arteries, as it is occasioned either by excess or defect of stimulus, or of sensorial power, exists both in the cold and hot fits of fever; but when the cold fit ceases, and the pulse becomes strong and full as well as quick, in consequence of the increased irritability of the heart and arteries, it constitutes the irritative fever, or synocha. It is attended with considerable heat during the paroxysm, and generally terminates in a quarter of a lunation, without any disturbance of the faculties of the mind. See Class IV. 1. 1. 8. M. M. Venesection. Emetics. Cathartics. Cool the patient in the hot fit, and warm him in the cold one. Rest. Torpentia. 2. _Ebrietas._ Drunkenness. By the stimulus of wine or opium the whole arterial system, as well as every other part of the moving system, is excited into increased action. All the secretions, and with them the production of sensorial power itself in the brain, seem to be for a time increased, with an additional quantity of heat, and of pleasureable sensation. See Sect. XXI. on this subject. This explains, why at the commencement of the warm paroxysm of some fevers the patient is in greater spirits, or vivacity; because, as in drunkenness, the irritative motions are all increased, and a greater production of sensation is the consequence, which when in a certain degree, is pleasureable, as in the diurnal fever of weak people. Sect. XXXVI. 3. 1. 3. _Hæmorrhagia arteriosa._ Arterial hæmorrhage. Bleeding with a quick, strong, and full pulse. The hæmorrhages from the lungs, and from the nose, are the most frequent of these; but it sometimes happens, that a small artery but half divided, or the puncture of a leech, will continue to bleed pertinaciously. M. M. Venesection. Cathartic with calomel. Divide the wounded artery. Bind sponge on the puncture. If coffee or charcoal internally? If air with less oxygen? 4. _Hæmoptoe arteriosa._ Spitting of arterial blood. Blood spit up from the lungs is florid, because it has just been exposed to the influence of the air in its passage through the extremities of the pulmonary artery; it is frothy, from the admixture of air with it in the bronchia. The patients frequently vomit at the same time from the disagreeable titillation of blood about the fauces; and are thence liable to believe, that the blood is rejected from the stomach. Sometimes an hæmoptoe for several successive days returns in gouty persons without danger, and seems to supply the place of the gouty paroxysms. Is not the liver always diseased previous to the hæmoptoe, as in several other hæmorrhages? See Class I. 2. 1. 9. M. M. Venesection, a purge, a blister, diluents, torpentia; and afterwards sorbentia, as the bark, the acid of vitriol, and opium. An emetic is said to stop a pulmonary hæmorrhage, which it may effect, as sickness decreases the circulation, as is very evident in the great sickness sometimes produced by too large a dose of digitalis purpurea. Dr. Rush says, a table spoonful or two of common salt is successful in hæmoptoe; this may be owing to its stimulating the absorbent systems, both the lymphatic, and the venous. Should the patient respire air with less oxygen? or be made sick by whirling round in a chair suspended by a rope? One immersion in cold water, or a sudden sprinkling all over with cold water, would probably stop a pulmonary hæmorrhage. See Sect. XXVII. 1. 5. _Hæmorrhagia narium._ _Epistaxis_. Bleeding at the nose in elderly subjects most frequently attends those, whose livers are enlarged or inflamed by the too frequent use of fermented liquors. In boys it occurs perhaps simply from redundancy of blood; and in young girls sometimes precedes the approach of the catamenia; and then it shews a disposition contrary to chlorosis; which arises from a deficiency of red blood. M. M. It is stopped by plunging the head into cold water, with powdered salt hastily dissolved in it; or sometimes by lint strewed over with wheat flour put up the nostrils; or by a solution of steel in brandy applied to the vessel by means of lint. The cure in other respects as in hæmoptoe; when the bleeding recurs at certain periods, after venesection, and evacuation by calomel, and a blister, the bark and steel must be given, as in intermittent fevers. See Section XXVII. 1. * * * * * ORDO I. _Increased Irritation._ GENUS II. _With increased Actions of the Secerning System._ These are always attended with increase of partial or of general heat; for the secreted fluids are not simply separated from the blood, but are new combinations; as they did not previously exist as such in the blood vessels. But all new combinations give out heat chemically; hence the origin of animal heat, which is always increased in proportion to the secretion of the part affected, or to the general quantity of the secretions. Nevertheless there is reason to believe, that as we have a sense purposely to distinguish the presence of greater or less quantities of heat, as mentioned in Sect. XIV. 6. so we may have certain minute glands for the secretion of this fluid, as the brain is believed to secrete the sensorial power, which would more easily account for the instantaneous production of the blush of shame, and of anger. This subject deserves further investigation. SPECIES. 1. _Calor febrilis._ The heat in fevers arises from the increase of some secretion, either of the natural fluids, as in irritative fevers; or of new fluids, as in infectious fevers; or of new vessels, as in inflammatory fevers. The pain of heat is a consequence of the increased extension or contraction of the fibres exposed to so great a stimulus. See CLASS I. 1. 5. 6. 2. _Rubor febrilis._ Febrile redness. When the cold fit of fever terminates, and the pulsations of the heart and arteries become strong as well as quick from the increase of their irritability after their late quiescence, the blood is impelled forwards into the fine extremities of the arteries, and the anastomozing capillaries, quicker than the extremities of the veins can absorb and return it to the heart. Hence the pulse at the wrist becomes full, as well as quick and strong, and the skin glows with arterial blood, and the veins become empty and less visible. In elderly people the force of the heart and arteries becomes less, while the absorbent power of the veins remains the same; whence the capillary vessels part with the blood, as soon as it is received, and the skin in consequence becomes paler; it is also probable, that in more advanced life some of the finer branches of the arteries coalesce, and become impervious, and thus add to the opacity of the skin. 3. _Sudor calidus._ Warm sweat may be divided into four varieties, according to their remote causes. _First_, the perspirable matter is secreted in as great quantity during the hot fit of fever, as towards the end of it, when the sweat is seen upon the skin. But during the hot fit the cutaneous absorbents act also with increased energy, and the exhalation is likewise increased by the greater heat of the skin; and hence it does not appear in drops on the surface, but is in part reabsorbed, and in part dissipated in the atmosphere. But as the mouths of the cutaneous absorbents are exposed to the cool air or bedclothes; whilst those of the capillary glands, which secrete the perspirable matter, are exposed to the warmth of the circulating blood; the former, as soon as the fever-fit begins to decline, lose their increased action first; and hence the absorption of the sweat is diminished, whilst the increased secretion of it continues for some hours afterwards, which occasions it to stand in drops upon the skin. As the skin becomes cooler, the evaporation of the perspirable matter becomes less, as well as the absorption of it. And hence the dissipation of aqueous fluid from the body, and the consequent thirst, are perhaps greater during the hot fit, than during the subsequent sweat. For the sweats do not occur, according to Dr. Alexander's experiments, till the skin is cooled from 112 to 108 degrees of heat; that is, till the paroxysm begins to decline. From this it appears, that the sweats are not critical to the hot fit, any more than the hot fit can be called critical to the cold one; but simply, that they are the natural consequence of the decline of the hot fit, commencing with the decreased action of the absorbent system, and the decreased evaporation from the skin. And from hence it may be concluded, that a fever-fit is not in general an effort of nature to restore health, as Sydenham considered it, but a necessary consequence of the previous torpor; and that the causes of fevers would be less detrimental, if the fever itself could be prevented from existing; as appears in the cool treatment of the small-pox. It must be noted that the profuse sweats on the skin are more frequent at the decline of fever-fits than the copious urine, or loose stools, which are mentioned below; as the cutaneous absorbents, being exposed to the cool air, lose their increased action sooner than the urinary or intestinal absorbents; which open into the warm cavities of the bladder and intestines; but which are nevertheless often affected by their sympathy with the cutaneous absorbents. Hence few fevers terminate without a moisture of the skin; whence arose the fatal practice of forcing sweats by the external warmth of air or bedclothes in fevers; for external warmth increases the action of the cutaneous capillaries more than that of the other secerning vessels; because the latter are habituated to 98 degrees of heat, the internal warmth of the body; whereas the cutaneous capillaries being nearer the surface are habitually kept cooler by the contact of the external air. Sweats thus produced by heat in confined rooms are still more detrimental; as the air becomes then not only deprived of a part of its oxygene by frequent respiration, but is loaded with animal effluvia as well as with moisture, till it can receive no more; and in consequence, while the cutaneous secretion stands upon the skin in drops for want of exhalation, the lungs are exposed to an insalubrious atmosphere. I do not deny, that sweating may be so managed as to be serviceable in preventing the return of the cold paroxysm of fevers; like the warm bath, or any other permanent stimulus, as wine, or opium, or the bark. For this purpose it should be continued till past the time of the expected cold fit, supported by moderate doses of wine-whey, with spirit of hartshorn, and moderate degrees of warmth. Its salutary effect, when thus managed, was probably one cause of its having been so much attended to; and the fetid smell, which when profuse is liable to accompany it, gave occasion to the belief, that the supposed material cause of the disease was thus eliminated from the circulation. When too great external heat is applied, the system is weakened by excess of action, and the torpor which causes the cold paroxysm recurs sooner and more violently. For though some stimuli, as of opium and alcohol, at the same time that they exhaust the sensorial power by promoting increase of fibrous action, may also increase the production or secretion of it in the brain, yet experience teaches us, that the exhaustion far out-balances the increased production, as is evinced by the general debility, which succeeds intoxication. In respect to the fetor attending copious continued sweats, it is owing to the animalized part of this fluid being kept in that degree of warmth, which most favours putrefaction, and not suffered to exhale into the atmosphere. Broth, or other animal mucus, kept in similar circumstances, would in the same time acquire a putrid smell; yet has this error frequently produced miliary eruptions, and increased every kind of inflammatory or sensitive fever. The ease, which the patient experiences during sweating, if it be not produced by much external heat, is similar to that of the warm bath; which by its stimulus applied to the cutaneous vessels, which are generally cooler than the internal parts of the system, excites them into greater action; and pleasureable sensation is the consequence of these increased actions of the vessels of the skin. From considering all these circumstances, it appears that it is not the evacuation by sweats, but the continued stimulus, which causes and supports those sweats, which is serviceable in preventing the returns of fever-fits. And that sweats too long continued, or induced by too great stimulus of warmth, clothes, or medicines, greatly injure the patient by increasing inflammation, or by exhausting the sensorial power. See Class I. 1. 2. 14. _Secondly_, The sweats produced by exercise or labour are of the warm kind; as they originate from the increased action of the capillaries of the skin, owing to their being more powerfully stimulated by the greater velocity of the blood, and by a greater quantity of it passing through them in a given time. For the blood during violent exercise is carried forwards by the action of the muscles faster in the arteries, than it can be taken up by the veins; as appears by the redness of the skin. And from the consequent sweats, it is evinced, that the secretory vessels of the skin during exercise pour out the perspirable matter faster, than the mouths of the absorbent vessels can drink it up. Which mouths are not exposed to the increased muscular action, or to the stimulus of the increased velocity and quantity of the blood, but to the cool air. _Thirdly_, the increased secretion of perspirable matter occasioned by the stimulus of external heat belongs likewise to this place; as it is caused by the increased motions of the capillary vessels; which thus separate from the blood more perspirable matter, than the mouths of their correspondent absorbent vessels can take up; though these also are stimulated by external heat into more energetic action. If the air be stationary, as in a small room, or bed with closed curtains, the sweat stands in drops on the skin for want of a quicker exhalation proportioned to the quicker secretion. A _fourth_ variety of warm perspiration is that occasioned by stimulating drugs, of which opium and alcohol are the most powerful; and next to these the spices, volatile alkali, and neutral salts, especially sea salt; that much of the aqueous part of the blood is dissipated by the use of these drugs, is evinced by the great thirst, which occurs a few hours after the use of them. See Art. III. 2. 12. and Art. III. 2. 1. We may from hence understand, that the increase of this secretion of perspirable matter by artificial means, must be followed by debility and emaciation. When this is done by taking much salt, or salted meat, the sea-scurvy is produced; which consists in the inirritability of the bibulous terminations of the veins arising from the capillaries; see Class I. 2. 1. 14. The scrophula, or inirritability of the lymphatic glands, seems also to be occasionally induced by an excess in eating salt added to food of bad nourishment. See Class I. 2. 3. 21. If an excess of perspiration is induced by warm or stimulant clothing, as by wearing flannel in contact with the skin in the summer months, a perpetual febricula is excited, both by the preventing the access of cool air to the skin, and by perpetually goading it by the numerous and hard points of the ends of the wool; which when applied to the tender skins of young children, frequently produce the red gum, as it is called; and in grown people, either an erysipelas, or a miliary eruption, attended with fever. See Class II. 1. 3. 12. Shirts made of cotton or calico stimulate the skin too much by the points of the fibres, though less than flannel; whence cotton handkerchiefs make the nose sore by frequent use. The fibres of cotton are, I suppose, ten times shorter than those of flax, and the number of points in consequence twenty times the number; and though the manufacturers singe their calicoes on a red-hot iron cylinder, yet I have more than once seen an erysipelas induced or increased by the stimulus of calico, as well as of flannel. The increase of perspiration by heat either of clothes, or of fire, contributes much to emaciate the body; as is well known to jockeys, who, when they are a stone or two too heavy for riding, find the quickest way to lessen their weight is by sweating themselves between blankets in a warm room; but this likewise is a practice by no means to be recommended, as it weakens the system by the excess of so general a stimulus, brings on a premature old age, and shortens the span of life; as may be further deduced from the quick maturity, and shortness of the lives, of the inhabitants of Hindostan, and other tropical climates. M. Buffon made a curious experiment to shew this circumstance. He took a numerous brood of the butterflies of silkworms, some hundreds of which left their eggs on the same day and hour; these he divided into two parcels; and placing one parcel in the south window, and the other in the north window of his house, he observed, that those in the colder situation lived many days longer than those in the warmer one. From these observations it appears, that the wearing of flannel clothing next the skin, which is now so much in fashion, however useful it may be in the winter to those, who have cold extremities, bad digestions, or habitual coughs, must greatly debilitate them, if worn in the warm months, producing fevers, eruptions, and premature old age. See Sect. XXXVII. 5. Class I. 1. 2. 14. Art. III. 2. 1. 4. _Urina uberior colorata._ Copious coloured urine. Towards the end of fever-fits a large quantity of high coloured urine is voided, the kidneys continuing to act strongly, after the increased action of the absorbents of the bladder is somewhat diminished. If the absorbents continue also to act strongly, the urine is higher coloured, and so loaded as to deposit, when cool, an earthy sediment, erroneously thought to be the material cause of the disease; but is simply owing to the secretion of the kidnies being great from their increased action; and the thinner parts of it being absorbed by the increased action of the lymphatics, which are spread very thick on the neck of the bladder; for the urine, as well as perhaps all the other secreted fluids, is produced from the kidnies in a very dilute state; as appears in those, who from the stimulus of a stone, or other cause, evacuate their urine too frequently; which is then pale from its not having remained in the bladder long enough for the more aqueous part to have been reabsorbed. The general use of this urinary absorption to the animal oeconomy is evinced from the urinary bladders of fish, which would otherwise be unnecessary. High coloured urine in large quantity shews only, that the secreting vessels of the kidnies, and the absorbents of the bladder, have acted with greater energy. When there is much earthy sediment, it shews, that the absorbents have acted proportionally stronger, and have consequently left the urine in a less dilute state. In this urine the transparent sediment or cloud is mucous; the opake sediment is probably coagulable lymph from the blood changed by an animal or chemical process. The floating scum is oil. The angular concretions to the sides of the pot, formed as the urine cools, is microcosmic salt. Does the adhesive blue matter on the sides of the glass, or the blue circle on it at the edge of the upper surface of the urine, consist of Prussian blue? 5. _Diarrhoea calida._ Warm diarrhoea. This species may be divided into three varieties deduced from their remote causes, under the names of diarrhoea febrilis, diarrhoea crapulosa, and diarrhoea infantum. The febrile diarrhoea appears at the end of fever-fits, and is erroneously called critical, like the copious urine, and the sweats; whereas it arises from the increased action of those secerning organs, which pour their fluids into the intestinal canal (as the liver, pancreas, and mucous glands), continuing longer than the increased action of the intestinal absorbents. In this diarrhoea there is no appearance of curdled chyle in the stools, as occurs in cholera. I. 3. 1. 5. The _diarrhoea crapulosa_, or diarrhoea from indigestion, occurs when too great a quantity of food or liquid has been taken; which not being compleatly digested, stimulates the intestines like any other extraneous acrid material; and thus produces an increase of the secretions into them of mucus, pancreatic juice, and bile. When the contents of the bowels are still more stimulant, as when drastic purges, or very putrescent diet, have been taken, a cholera is induced. See Sect. XXIX. 4. The _diarrhoea infantum_, or diarrhoea of infants, is generally owing to too great acidity in their bowels. Milk is found curdled in the stomachs of all animals, old as well as young, and even of carnivorous ones, as of hawks. (Spallanzani.) And it is the gastric juice of the calf, which is employed to curdle milk in the process of making cheese. Milk is the natural food for children, and must curdle in their stomachs previous to digestion; and as this curdling of the milk destroys a part of the acid juices of the stomach, there is no reason for discontinuing the use of it, though it is occasionally ejected in a curdled state. A child of a week old, which had been taken from the breast of its dying mother, and had by some uncommon error been suffered to take no food but water-gruel, became sick and griped in twenty-four hours, and was convulsed on the second day, and died on the third! When all young quadrupeds, as well as children, have this natural food of milk prepared for them, the analogy is so strong in favour of its salubrity, that a person should have powerful testimony indeed of its disagreeing, before he advises the discontinuance of the use of it to young children in health, and much more so in sickness. The farmers lose many of their calves, which are brought up by gruel, or gruel and old milk; and among the poor children of Derby, who are thus fed, hundreds are starved into the scrophula, and either perish, or live in a state of wretched debility. When young children are brought up without a breast, they should for the first two months have no food but new milk; since the addition of any kind of bread or flour is liable to ferment, and produce too much acidity; as appears by the consequent diarrhoea with green dejections and gripes; the colour is owing to a mixture of acid with the natural quantity of bile, and the pain to its stimulus. And they should never be fed as they lie upon their backs, as in that posture they are necessitated to swallow all that is put into their mouths; but when they are fed, as they are sitting up, or raised up, when they have had enough, they can permit the rest to run out of their mouths. This circumstance is of great importance to the health of those children, who are reared by the spoon, since if too much food is given them, indigestion, and gripes, and diarrhoea, is the consequence; and if too little, they become emaciated; and of this exact quantity their own palates judge the best. M. M. In this last case of the diarrhoea of children, the food should be new milk, which by curdling destroys part of the acid, which coagulates it. Chalk about four grains every six hours, with one drop of spirit of hartshorn, and half a drop of laudanum. But a blister about the size of a shilling is of the greatest service by restoring the power of digestion. See Article III. 2. 1. in the subsequent Materia Medica. 6. _Salivatio calida._ Warm salivation. Increased secretion of saliva. This may be effected either by stimulating the mouth of the gland by mercury taken internally; or by stimulating the excretory duct of the gland by pyrethrum, or tobacco; or simply by the movement of the muscles, which lie over the gland, as in masticating any tasteless substance, as a lock of wool, or mastic. In about the middle of nervous fevers a great spitting of saliva sometimes occurs, which has been thought critical; but as it continues sometimes two or even three weeks without the relief of the patient, it may be concluded to arise from some accidental circumstance, perhaps not unsimilar to the hysteric ptyalisms mentioned in Class I. 3. 2. 2. See Sect. XXIV. M. M. Cool air, diluents, warm bath, evacuations. 7. _Catharrhus calidus._ Warm catarrh. Consists in an increased secretion of mucus from the nostrils without inflammation. This disease, which is called a cold in the head, is frequently produced by cold air acting for some time on the membranes, which line the nostrils, as it passes to the lungs in respiration. Whence a torpor of the action of the mucous glands is first introduced, as in I. 2. 3. 3. and an orgasm or increased action succeeds in consequence. Afterwards this orgasm and torpor are liable to alternate with each other for some time like the cold and hot fits of ague, attended with deficient or exuberant secretion of mucus in the nostrils. At other times it arises from reverse sympathy with some extensive parts of the skin, which have been exposed too long to cold, as of the head, or feet. In consequence of the torpor of these cutaneous capillaries those of the mucous membrane of the nostrils act with greater energy by reverse sympathy; and thence secrete more mucus from the blood. At the same time the absorbents, acting also with greater energy by their reverse sympathy with those of some distant part of the skin, absorb the thinner parts of the mucus more hastily; whence the mucus is both thicker and in greater quantity. Other curious circumstances attend this disease; the membrane becomes at times so thickened by its increased action in secreting the mucus, that the patient cannot breathe through his nostrils. In this situation if he warms his whole skin suddenly by fire or bed-clothes, or by drinking warm tea, the increased action of the membrane ceases by its reverse sympathy with the skin; or by the retraction of the sensorial power to other parts of the system; and the patient can breathe again through the nostrils. The same sometimes occurs for a time on going into the cold air by the deduction of heat from the mucous membrane, and its consequent inactivity or torpor. Similar to this when the face and breast have been very hot and red, previous to the eruption of the small-pox by inoculation, and that even when exposed to cool air, I have observed the feet have been cold; till on covering them with warm flannel, as the feet have become warm, the face has cooled. See Sect. XXXV. 1. 3. Class II. 1. 3. 5. IV. 2. 2. 10. IV. 1. 1. 5. M. M. Evacuations, abstinence, oil externally on the nose, warm diluent fluids, warm shoes, warm night-cap. 8. _Expectoratio calida._ Warm expectoration consists of the increased secretion of mucus from the membrane, which lines the bronchiæ, or air-cells of the lungs, without inflammation. This increased mucus is ejected by the action of coughing, and is called a cold, and resembles the catarrh of the preceding article; with which it is frequently combined. M. M. Inhale the steam of warm water, evacuations, warm bath, afterwards opium, sorbentia. 9. _Exsudatio pone aures._ A discharge behind the ears. This chiefly affects children, and is a morbid secretion; as appears from its fetor; for if it was owing to defect of absorption, it would be saline, and not fetid; if a morbid action has continued a considerable time, it should not be stopped too suddenly; since in that case some other morbid action is liable to succeed in its stead. Thus children are believed to have had cholics, or even convulsions, consequent to the too sudden healing of these morbid effusions behind their ears. The rationale of this is to be explained from a medical fact, which I have frequently observed; and that is, that a blister on the back greatly strengthens the power of digestion, and removes the heart-burn in adults, and green stools in children. The stimulus of the blister produces sensation in the vessels of the skin; with this additional sensorial power these vessels act more strongly; and with these the vessels of the internal membranes of the stomach and bowels act with greater energy from their direct sympathy with them. Now the acrid discharge behind the ears of children produces sensation on that part of the skin, and so far acts as a small blister. When this is suddenly stopped, a debility of the digestive power of the stomach succeeds from the want of this accustomed stimulus, with flatulency, green stools, gripes, and sometimes consequent convulsions. See Class II. 1. 5. 6. and II. 1. 4. 6. M. M. If the matter be absorbed, and produces swelling of the lymphatics of the neck, it should be cured as soon as possible by dusting the part with white lead, cerussa, in very fine powder; and to prevent any ill consequence an issue should be kept for about a month in the arm; or a purgative medicine should be taken, every other day for three or four times, which should consist of a grain of calomel, and three or four grains of rhubarb, and as much chalk. If there be no appearance of absorption, it is better only to keep the parts clean by washing them with warm water morning and evening; or putting fuller's earth on them; especially till the time of toothing is past. The tinea, or scald head, and a leprous eruption, which often appears behind the ears, are different diseases. 10. _Gonorrhea calida._ Warm gleet. Increased discharge of mucus from the urethra or prostrate gland without venereal desire, or venereal infection. See Class I. 2. 3. 8. M. M. Cantharides, balsams, rhubarb, blister in perinæum, cold bath, injections of metallic salts, flannel shirt, change of the form of the accustomed chair or saddle of the patient. 11. _Fluor albus calidus._ Warm fluor albus. Increased secretion of mucus in the vagina or uterus without venereal desire or venereal infection. It is distinguished from the fluor albus frigidus by the increased sense of warmth in the part, and by the greater opacity or spissitude of the material discharged; as the thinner parts are reabsorbed by the increased action of the absorbents, along with the saline part, whence no smarting or excoriation attends it. M. M. Mucilage, as isinglass, hartshorn jelly, gum arabic. Ten grains of rhubarb every night. Callico or flannel shift, opium, balsams. See Class I. 2. 3. 7. 12. _Hæmorrhois alba._ White piles. An increased discharge of mucus from the rectum frequently mistaken for matter; is said to continue a few weeks, and recur like the bleeding piles; and to obey lunar influence. See Class I. 2. 1. 6. M. M. Abstinence from vinous spirit. Balsam of copaiva. Spice swallowed in large fragments, as ten or fifteen black pepper-corns cut in half, and taken after dinner and supper. Ward's paste, consisting of black pepper and the powdered root of Helenium Enula. 13. _Serum e vesicatorio._ Discharge from a blister. The excretory ducts of glands terminate in membranes, and are endued with great irritability, and many of them with sensibility; the latter perhaps in consequence of their facility of being excitable into great action; instances of this are the terminations of the gall-duct in the duodenum, and of the salivary and lachrymal glands in the mouth and eye; which produce a greater secretion of their adapted fluids, when the ends of their excretory ducts are stimulated. The external skin consists of the excretory ducts of the capillaries, with the mouths of the absorbents; when these are stimulated by the application of cantharides, or by a slice of the fresh root of bryonia alba bound on it, the capillary glands pour an increased quantity of fluid upon the skin by their increased action; and the absorbent vessels imbibe a greater quantity of the more fluid and saline part of it; whence a thick mucous or serous fluid is deposited between the skin and cuticle. 14. _Perspiratio foetida._ Fetid perspiration. The uses of the perspirable matter are to keep the skin soft and pliant, for the purposes of its easier flexibility during the activity of our limbs in locomotion, and for the preservation of the accuracy of the sense of touch, which is diffused under the whole surface of it to guard us against the injuries of external bodies; in the same manner as the secretion of tears is designed to preserve the cornea of the eye moist, and in consequence transparent; yet has this cutaneous mucus been believed by many to be an excrement; and I know not how many fanciful theories have been built on its supposed obstruction. Such as the origin of catarrhs, coughs, inflammations, erysypelas, and herpes. To all these it may be sufficient to answer, that the antient Grecians oiled themselves all over; that some nations have painted themselves all over, as the Picts of this island; that the Hottentots smear themselves all over with grease. And lastly, that many of our own heads at this day are covered with the flour of wheat and the fat of hogs, according to the tyranny of a filthy and wasteful fashion, and all this without inconvenience. To this must be added the strict analogy between the use of the perspirable matter and the mucous fluids, which are poured for similar purposes upon all the internal membranes of the body; and besides its being in its natural state inodorous; which is not so with the other excretions of feces, or of urine. In some constitutions the perspirable matter of the lungs acquires a disagreeable odour; in others the axilla, and in others the feet, emit disgustful effluvia; like the secretions of those glands, which have been called odoriferæ; as those, which contain the castor in the beaver, and those within the rectum of dogs, the mucus of which has been supposed to guard them against the great costiveness, which they are liable to in hot summers; and which has been thought to occasion canine madness, but which, like their white excrement, is more probably owing to the deficient secretion of bile. Whether these odoriferous particles attend the perspirable matter in consequence of the increased action of the capillary glands, and can properly be called excrementitous; that is, whether any thing is eliminated, which could be hurtful if retained; or whether they may only contain some of the essential oil of the animal; like the smell, which adheres to one's hand on stroking the hides of some dogs; or like the effluvia, which is left upon the ground, from the feet of men and other creatures; and is perceptible by the nicer organs of the dogs, which hunt them, may admit of doubt. M. M. Wash the parts twice a day with soap and water; with lime water; cover the feet with oiled silk socks, which must be washed night and morning. Cover them with charcoal recently made red hot, and beaten into fine powder and sifted, as soon as cold, and kept well corked in a bottle, to be warned off and renewed twice a day. Internally rhubarb grains vi. or viii. every night, so as to procure a stool or two extraordinary every day, and thus by increasing one evacuation to decrease another. Cool dress, diluting liquids? 15. _Crines novi._ New hairs. The black points on the faces of some people consist of mucus, which is become viscid, and which adheres in the excretory ducts of the glands of the skin; as described in Class I. 2. 2. 9. and which may be pressed out by the fingers, and resembles little worms. Similar to this would seem the fabrication of silk, and of cobweb by the silk worm and spider; which is a secreted matter pressed through holes, which are the excretory ducts of glands. And it is probable, that the production of hair on many parts of the body, and at different periods of life, may be effected by a similar process; and more especially as every hair may be considered as a slender flexible horn, and is an appendage of the skin. See Sect. XXXIX. 3. 2. Now as there is a sensitive sympathy between the glands, which secrete the semen, and the throat, as appears in the mumps; see Hydrophobia, Class IV. 1. 2. 7. and Parotitis, Class IV. 1. 2. 19. The growth of the beard at puberty seems to be caused by the greater action of the cutaneous glands about the chin and pubes in consequence of their sympathy with those of the testes. But this does not occur to the female sex at their time of puberty, because the sensitive sympathy in them seems to exist between the submaxillary glands, and the pectoral ones; which secrete the milk, and afford pleasure both by that secretion, and by the erection of the mamulæ, or nipples; and by delivering the milk into the mouth of the child; this sensitive sympathy of the pectoral and submaxillary glands in women is also observable in the Parotitis, or mumps, as above referred to. When hairs grow on the face or arms so as to be disagreeable, they may be thus readily removed without pain or any ill consequence. Warm the ends of a pair of nippers or forceps, and stick on them a little rosin, or burgundy pitch; by these means each single hair may be taken fast hold of; and if it be then plucked off slowly, it gives pain; but if plucked off suddenly, it gives no pain at all; because the vis inertiæ of the part of the skin, to which it adheres, is not overcome; and it is not in consequence separated from the cellular membrane under it. Some of the hairs may return, which are thus plucked off, or others may be induced to grow near them; but in a little time they may be thus safely destroyed; which is much to be preferred to the methods said to be used in Turkey to eradicate hair; such as a mixture of orpiment and quick lime; or of liver of sulphur in solution; which injure the skin, if they are not very nicely managed; and the hair is liable to grow again as after shaving; or to become white, if the roots of it have been much inflamed by the causticity of the application. See Class I. 2. 2. 11. on grey hairs. * * * * * ORDO I. _Increased Irritation._ GENUS III. _With increased Actions of the Absorbent System._ These are not attended with so great increase of heat as in the former genus, because the fluids probably undergo less chemical change in the glands of the absorbent system; nor are the glands of the absorbent vessels so numerous or so extensive as those of the secerning ones. Yet that some heat is produced by the increased action of the absorbents appears from the greater general warmth of the skin and extremities of feeble patients after the exhibition of the peruvian bark, and other medicines of the article Sorbentia. SPECIES. 1. _Lingua arida._ Dry tongue occurs in those fevers, where the expired air is warmer than natural; and happens to all those, who sleep with their mouths open; the currents of air in respiration increasing the evaporation. There is also a dryness in the mouth from the increased action of the absorbent vessels, when a sloe or a crab-apple are masticated; and after the perforation has been much increased by eating salt or spice, or after other copious secretions; as after drunkenness, cathartics, or fever fits, the mucus of the mouth becomes viscid, and in small quantity, from the increased absorption, adhering to the tongue like a white slough. In the diabætes, where the thirst is very great, this slough adheres more pertinaciously, and becomes black or brown, being coloured after a few days by our aliment or drink. The inspissated mucus on the tongue of those, who sleep with their mouths open, is sometimes reddened as if mixed with blood, and sometimes a little blood follows the expuition of it from the fauces owing to its great adhesion. When this mucus adheres long to the papillæ of the tongue, the saliva, which it contains in its interstices, like a sponge, is liable to become putrid, and to acquire a bitter taste, like other putrid animal substances; which is generally mistaken for an indication of the presence of bile. M. M. Warm subacid liquids. See Class I. 2. 5. 8. 2. _Fauces aridæ._ Dry throat. The expuition of a frothy mucus with great and perpetual hawking occurs in hydrophobia, and is very distressing to the patient; which may be owing to the increased irritability or sensibility of the upper part of the oesophagus, which will not permit any fluid to rest on it. It affects some people after intoxication, when the lungs remain slightly inflamed, and by the greater heat of the air in expiration the mucus becomes too hastily evaporated, and is expectorated with difficulty in the state of white froth. I knew a person, who for twenty years always waked with his tongue and throat quite dry; so that he was necessitated to take a spoonful of water, as soon as he awoke; otherwise a little blood always followed the forcible expuition of the indurated mucus from his fauces. See Class II. 1. 3. 17. M. M. Steel-springs fixed to the night-cap so as to suspend the lower jaw and keep it closed; or springs of elastic gum. Or a pot of water suspended over the bed, with a piece of list, or woollen cloth, depending from it, and held in the mouth; which will act like a syphon, and slowly supply moisture, or barley water should be frequently syringed into the mouth of the patient. 3. _Nares aridi._ Dry nostrils with the mucus hardening upon their internal surface, so as to cover them with a kind of skin or scale, owing to the increased action of the absorbents of this membrane; or to the too great dryness of the air, which passes into the lungs; or too great heat of it in its expiration. When air is so dry as to lose its transparency; as when a tremulous motion of it can be seen over corn fields in a hot summer's day; or when a dry mist, or want of transparency of the air, is visible in very hot weather; the sense of smell is at the same time imperfect from the dryness of the membrane, beneath which it is spread. 4. _Expectoratio solida._ Solid expectoration. The mucus of the lungs becomes hardened by the increased absorption, so that it adheres and forms a kind of lining in the air-cells, and is sometimes spit up in the form of branching vessels, which are called polypi of the lungs. See Transact. of the College, London. There is a rattling or weezing of the breath, but it is not at first attended with inflammation. The Cynanche trachealis, or Croup, of Dr. Cullen, or Angina polyposa of Michaelis, if they differ from the peripneumony of infants, seem to belong to this genus. When the difficulty of respiration is great, venesection is immediately necessary, and then an emetic, and a blister. And the child should be kept nearly upright in bed as much as may be. See Tonsillitis, Class II. 1. 3. 3. M. M. Diluents, emetics, essence of antimony, foetid gums, onions, warm bath for half an hour every day for a month. Inhaling the steam of water, with or without volatile alcali. Soap. 5. _Constipatio alvi._ Costiveness from increased action of the intestinal absorbents. The feces are hardened in lumps called scybala; which are sometimes obliged to be extracted from the rectum with a kind of marrow spoon. This is said to have happened from the patient having taken much rust of iron. The mucus is also hardened so as to line the intestines, and to come away in skins, rolled up as they pass along, so as to resemble worms, for which they are frequently mistaken; and sometimes it is evacuated in still larger pieces, so as to counterfeit the form of the intestines, and has been mistaken for a portion of them. Balls of this kind, nearly as heavy as marble, and considerably hard, from two inches to five in diameter, are frequently found in the bowels of horses. Similar balls found in goats have been called Bezoar. M. M. Cathartics, Diluents, fruit, oil, soap, sulphur, warm bath. Sprinkling with cold water, cool clothing. See Class I. 2. 4. 18. 6. _Cutis arida._ Dry skin. This dry skin is not attended with coldness as in the beginning of fever-fits. Where this cutaneous absorption is great, and the secreted material upon it viscid, as on the hairy scalp, the skin becomes covered with hardened mucus; which adheres so as not to be easily removed, as the scurf on the head; but is not attended with inflammation like the Tinea, or Lepra. The moisture, which appears on the skin beneath resinous or oily plasters, or which is seen to adhere to such plasters, is owing to their preventing the exhalation of the perspirable matter, and not to their increasing the production of it, as some have idly imagined. M. M. Warm bathing, oil externally, oil-skin gloves, resinous plasters. Wax. 7. _Urina parca colorata._ Diminished urine, which is high coloured, and deposits an earthy sediment, when cold, is owing to the great action of the urinary absorbents. See Class I. 1. 2. 4. In some dropsies the cutaneous absorbents are paralytic, as well as those opening into the cellular membrane; and hence, no moisture being acquired from the atmosphere, or from the cellular membrane, great thirst is excited; and great absorption from all parts, where the absorbents are still capable of action. Hence the urine is in very small quantity, and of deep colour, with copious sediment; and the kidneys are erroneously blamed for not doing their office; stimulant diuretic medicines are given in vain; and very frequently the unhappy patient is restrained from quenching his thirst, and dies a martyr to false theory. M. M. Diluent liquids, and warm bathing, are the natural cure of this symptom; but it generally attends those dropsies, which are seldom curable; as they are owing to a paralysis both of the cutaneous and cellular lymphatics. 8. _Calculus felleus._ Gall-stone. From the too hasty absorption of the thinner parts of the bile, the remainder is left too viscid, and crystallizes into lumps; which, if too large to pass, obstruct the ductus choledochus, producing pain at the pit of the stomach, and jaundice. When the indurated bile is not harder than a boiled pea, it may pass through the bile-duct with difficulty by changing its form; and thus gives those pains, which have been called spasms of the stomach; and yet these viscid lumps of bile may afterwards dissolve, and not be visible among the feces. In two instances I have seen from thirty to fifty gall-stones voided after taking an oil vomit as below. They were about the size of peas, and distinguishable when dry by their being inflammable like bad wax, when put into the flame of a candle. For other causes of jaundice, see Class I. 2. 4. 19. M. M. Diluents, daily warm bathing. Ether mixed with yolk of egg and water. Unboiled acrid vegetables, as lettice, cabbage, mustard, and cresses. When in violent pain, four ounces of oil of olives, or of almonds, should be swallowed; and as much more in a quarter of an hour, whether it stays or not. The patient should lie on the circumference of a large barrel, first on one side, and then on the other. Electric shocks through the gall-duct. Factitious Selter's water made by dissolving one dram of Sal Soda in a pint of water; to half a pint of which made luke-warm add ten drops of marine acid; to be drank as soon as mixed, twice a day for some months. Opium must be used to quiet the pain, if the oil does not succeed, as two grains, and another grain in half an hour if necessary. See Class IV. 2. 2. 4. 9. _Calculus renis._ Stone of the kidney. The pain in the loins and along the course of the ureter from a stone is attended with retraction of the testicle in men, and numbness on the inside of the thigh in women. It is distinguished from the lumbago or sciatica, as these latter are seldom attended with vomiting, and have pain on the outside of the thigh, sometimes quite down to the ankle or heel. See Herpes and Nephritis. Where the absorption of the thinner parts of the secretion takes place too hastily in the kidnies, the hardened mucus, and consequent calculous concretions, sometimes totally stop up the tubuli uriniferi; and no urine is secreted. Of this many die, who have drank much vinous spirit, and some of them recover by voiding a quantity of white mucus, like chalk and water; and others by voiding a great quantity of sand, or small calculi. This hardened mucus frequently becomes the nucleus of a stone in the bladder. The salts of the urine, called microcosmic salt, are often mistaken for gravel, but are distinguishable both by their angles of crystallization, their adhesion to the sides or bottom of the pot, and by their not being formed till the urine cools. Whereas the particles of gravel are generally without angles, and always drop to the bottom of the vessel, immediately as the water is voided. Though the proximate cause of the formation of the calculous concretions of the kidneys, and of chalk-stones in the gout, and of the insoluble concretions of coagulable lymph, which are found on membranes, which have been inflamed in peripneumony, or rheumatism, consists in the too great action of the absorbent vessels of those parts; yet the remote cause in these cases is probably owing to the inflammation of the membranes; which at that time are believed to secrete a material more liable to coagulate or concrete, than they would otherwise produce by increased action alone without the production of new vessels, which constitutes inflammation. As defined in Class II. 1. 2. The fluids secreted from the mucous membranes of animals are of various kinds and consistencies. Hair, silk, scales, horns, fingernails, are owing to natural processes. Gall-stones, stones found in the intestines of horses, scurf of the skin in leprosy, stones of the kidnies and bladder, the callus from the inflamed periosteum, which unites broken bones, the calcareous cement, which repairs the injured shells of snails, the calcareous crust on the eggs of birds, the annually renewed shells of crabs, are all instances of productions from mucous membranes, afterwards indurated by absorption of their thinner parts. All these concretions contain phosphoric acid, mucus, and calcareous earth in different proportions; and are probably so far analogous in respect to their component parts as well as their mode of formation. Some calcareous earth has been discovered after putrefaction in the coagulable lymph of animals. Fordyce's Elements of Practice. A little calcareous earth was detected by Scheel or Bergman in the calculus of the bladder with much phosphoric acid, and a great quantity of phosphoric acid is shewn to exist in oyster-shells by their becoming luminous on exposing them a while to the sun's light after calcination; as in the experiments of Wilson. Botanic Garden, P. 1. Canto 1. l. 182, note. The exchange of which phosphoric acid for carbonic acid, or fixed air, converts shells into limestone, producing mountains of marble, or calcareous strata. Now as the hard lumps of calcareous matter, termed crabs' eyes, which are found in the stomachs of those animals previous to the annual renewal of their shells, are redissolved, probably by their gastric acid, and again deposited for that purpose; may it not be concluded, that the stone of the bladder might be dissolved by the gastric juice of fish of prey, as of crabs, or pike; or of voracious young birds, as young rooks or hawks, or even of calves? Could not these experiments be tried by collecting the gastric juice by putting bits of sponge down the throats of young crows, and retracting them by a string in the manner of Spallanzani? or putting pieces of calculus down the throat of a living crow, or pike, and observing if they become digested? and lastly could not gastric juice, if it should appear to be a solvent, be injected and born in the bladder without injury by means of catheters of elastic resin, or caoutchouc? M. M. Diluents. Cool dress. Frequent change of posture. Frequent horizontal rest in the day. Bathe the loins every morning with a sponge and cold water. Aerated alcaline water internally. Abstinence from all fermented or spirituous liquors. Whatever increases perspiration injures these patients, as it dissipates the aqueous particles, which ought to dilute the urine. When the constitution begins to produce gravel, it may I believe be certainly prevented by a total abstinence from fermented or spirituous liquors; by drinking much aqueous fluids; as toast and water, tea, milk and water, lemonade; and lastly by thin clothing, and sleeping on a hardish bed, that the patient may not lie too long on one side. See Class IV. 2. 2. 2. There is reason to believe, that the daily use of opium contributes to produce gravel in the kidnies by increasing absorption, when they are inflamed; in the same manner as is done by fermented or spirituous liquor. See Class I. 3. 2. 11. When the kidnies are so obstructed with gravel, that no urine passes into the bladder; which is known by the external appearance of the lower part of the abdomen, which, when the bladder is full, seems as if contracted by a cord between the navel and the bladder; and by the tension on the region of the bladder distinguishable by the touch; or by the introduction of the catheter; the following methods of cure are frequently successful. Venesection to six or eight ounces, ten grains of calomel, and an infusion of senna with salts and oil, every three hours, till stools are procured. Then an emetic. After the patient has been thus evacuated, a blister on the loins should be used; and from ten to twenty electric shocks should be passed through the kidnies, as large as can be easily borne, once or twice a day. Along with this method the warm bath should be used for an hour once or twice a day. After repeated evacuations a clyster, consisting of two drams of turpentine dissolved by yolk of egg, and sixty drops of tincture of opium, should be used at night, and repeated, with cathartic medicines interposed, every night, or alternate nights. Aerated solution of alcali should be taken internally, and balsam of copaiva, three or four times a day. Some of these patients recover after having made no water for nine or ten days. If a stone sticks in the ureter with incessant vomiting, ten grains of calomel must be given in small pills as above; and some hours afterwards infusion of senna and salts and oil, if it can be made to stay on the stomach. And after the purge has operated four or five times, an opiate is to be given, if the pain continues, consisting of two grains of opium. If this does not succeed, ten or twenty electric shocks through the kidney should be tried, and the purgative repeated, and afterwards the opiate. The patient should be frequently put into the warm bath for an hour at a time. Eighty or an hundred drops of laudanum given in a glyster, with two drams of turpentine, is to be preferred to the two grains given by the stomach as above, when the pain and vomiting are very urgent. 10. _Calculus vesicæ._ Stone of the bladder. The nucleus, or kernel, of these concretions is always formed in the kidney, as above described; and passing down the ureter into the bladder, is there perpetually increased by the mucus and salts secreted from the arterial system, or by the mucus of the bladder, disposed in concentric strata. The stones found in the bowels of horses are also formed on a nucleus, and consist of concentric spheres; as appears in sawing them through the middle. But as these are formed by the indurated mucus of the intestines alone without the urinary salts, it is probable a difference would be found on their analysis. As the stones of the bladder are of various degrees of hardness, and probably differ from each other in the proportions at least of their component parts; when a patient, who labours under this afflicting disease, voids any small bits of gravel; these should be kept in warm solutions of caustic alcali, or of mild alcali well aerated; and if they dissolve in these solutions, it would afford greater hopes, that that which remains in the bladder, might be affected by these medicines taken by the stomach, or injected into the bladder. To prevent the increase of a stone in the bladder much diluent drink should be taken; as half a pint of water warmed to about eighty degrees, three or four times a day: which will not only prevent the growth of it, by preventing any microcosmic salts from being precipitated from the urine, and by keeping the mucus suspended in it; but will also diminish the stone already formed, by softening, and washing away its surface. To this must be added cool dress, and cool bed-clothes, as directed above in the calculus renis. When the stone is pushed against or into the neck of the bladder, great pain is produced; this may sometimes be relieved by the introduction of a bougie to push the stone back into the fundus of the bladder. Sometimes by change of posture, or by an opiate either taken into the stomach, or by a clyster. A dram of sal soda, or of salt of tartar, dissolved in a pint of water, and well saturated with carbonic acid (fixed air), by means of Dr. Nooth's glass-apparatus, and drank every day, or twice a day, is the most efficacious internal medicine yet discovered, which can be easily taken without any general injury to the constitution. An aerated alcaline water of this kind is sold under the name of factitious Seltzer water, by J. Schweppe, at N^o 8, King's-street, Holborn, London; which I am told is better prepared than can be easily done in the usual glass-vessels, probably by employing a greater pressure in wooden ones. Lythotomy is the last recourse. Will the gastric juice of animals dissolve calculi? Will fermenting vegetable juices, as sweet-wort, or sugar and water in the act of fermentation with yest, dissolve any kind of animal concretions? 11. _Calculus arthriticus._ Gout-stones are formed on inflamed membranes, like those of the kidnies above described, by the too hasty absorption of the thinner and saline parts of the mucus. Similar concretions have been produced in the lungs, and even in the pericardium; and it is probable, that the ossification, as it is called, of the minute arteries, which is said to attend old age, and to precede some mortifications of the extremities, may be a process of this kind. As gout-stones lie near the surface, it is probable, that ether, frequently applied in their early state, might render them so liquid as to permit their reabsorption; which the stimulus of the ether might at the same time encourage. 12. _Rheumatismus chronicus._ Chronic rheumatism. After the acute rheumatism some inspissated mucus, or material similar to chalk-stones of the gout, which was secreted on the inflamed membrane, is probably left, owing to the too hasty absorption of the thinner and saline part of it; and by lying on the fascia, which covers some of the muscles, pains them, when they move and rub against it, like any extraneous material. The pain of the shoulder, which attends inflammations of the upper membrane of the liver, and the pains of the arms, which attend asthma dolorificum, or dropsy of the pericardium, are distinguished from the chronic rheumatism, as in the latter the pain only occurs on moving the affected muscles. M. M. Warm bath, cold bath, bandage of emplastrum de minio put on tight, so as to compress the part. Cover the part with flannel. With oiled silk. Rub it with common oil frequently. With ether. A blister. A warmer climate. Venesection. A grain of calomel and a grain of opium for ten successive nights. The Peruvian bark. 13. _Cicatrix vulnerum._ The scar after wounds. In the healing of ulcers the matter is first thickened by increasing the absorption in them; and then lessened, till all the matter is absorbed, which is brought by the arteries, instead of being deposed in the ulcer. M. M. This is promoted by bandage, by the sorbentia externally, as powder of bark, white lead; solution of sugar of lead. And by the sorbentia internally after evacuations. See Sect. XXXIII. 3. 2. In those ulcers, which are made by the contact of external fire, the violent action of the fibres, which occasions the pain, is liable to continue, after the external heat is withdrawn. This should be relieved by external cold, as of snow, salt and water recently mixed, ether, or spirits of wine suffered to evaporate on the part. The cicatrix of an ulcer generally proceeds from the edges of it; but in large ones frequently from the middle, or commences in several places at the same time; which probably contributes to the unevenness of large scars. 14. _Corneæ obfuscatio._ Opacity of the cornea. There are few people, who have passed the middle of life, who have not at some time suffered some slight scratches or injuries of the cornea, which by not healing with a perfectly smooth surface, occasion some refractions of light, which may be conveniently seen in the following manner: fill a tea-saucer with cream and tea, or with milk, and holding it to your lips, as if going to drink it, the imperfections of the cornea will appear like lines or blotches on the surface of the fluid, with a less white appearance than that surface. Those blemishes of the eye are distinguished from the muscæ volitantes described in Class I. 2. 5. 3. by their being invariably seen at any time, when you look for them. Ulcers may frequently be seen on the cornea after ophthalmy, like little pits or indentations beneath the surface of it: in this case no external application should be used, lest the scar should be left uneven; but the cure should be confined to the internal use of thirty grains of bark twice a day, and from five to ten drops of laudanum at night, with five grains of rhubarb, if necessary. After ulcers of the cornea, which have been large, the inequalities and opacity of the cicatrix obscures the sight; in this case could not a small piece of the cornea be cut out by a kind of trephine about the size of a thick bristle, or a small crow-quill, and would it not heal with a transparent scar? This experiment is worth trying, and might be done by a piece of hollow steel wire with a sharp edge, through which might be introduced a pointed steel screw; the screw to be introduced through the opake cornea to hold it up, and press it against the cutting edge of the hollow wire or cylinder; if the scar should heal without losing its transparency, many blind people might be made to see tolerably well by this slight and not painful operation. An experiment I wish strongly to recommend to some ingenious surgeon or oculist. * * * * * ORDO I. _Increased Irritation._ GENUS IV. _With increased Actions of other Cavities and Membranes._ SPECIES. 1. _Nictitatio irritativa._ Winking of the eyes is performed every minute without our attention, for the purpose of cleaning and moistening the eye-ball; as further spoken of in Class II. 1. 1. 8. When the cornea becomes too dry, it becomes at the same time less transparent; which is owing to the pores of it being then too large, so that the particles of light are refracted by the edges of each pore, instead of passing through it; in the same manner as light is refracted by passing near the edge of a knife. When these pores are filled with water, the cornea becomes again transparent. This want of transparency of the cornea is visible sometimes in dying people, owing to their inirritability, and consequent neglect of nictitation. The increase of transparency by filling the pores with fluid is seen by soaking white paper in oil; which from an opake body becomes very transparent, and accounts for a curious atmospheric phenomenon; when there exists a dry mist in a morning so as to render distant objects less distinct, it is a sign of a dry day; when distant objects are seen very distinct, it is a sign of rain. See Botan. Garden, Part I. add. note xxv. The particles of air are probably larger than those of water, as water will pass through leather and paper, which will confine air; hence when the atmosphere is much deprived of moisture, the pores of the dry air are so large, that the rays of light are refracted by their edges instead of passing through them. But when as much moisture is added as can be perfectly dissolved, the air becomes transparent; and opake again, when a part of this moisture collects into small spherules previous to its precipitation. This also accounts for the want of transparency of the air, which is seen in tremulous motions over corn-fields on hot summer-days, or over brick-kilns, after the flame is extinguished, while the furnace still remains hot. 2. _Deglutitio irritativa._ The deglutition of our saliva is performed frequently without our attention, and is then an irritative action in consequence of the stimulus of it in the mouth. Or perhaps sometimes for the purpose of diffusing a part of it over the dry membranes of the fauces and pharinx; in the same manner as tears are diffused over the cornea of the eye by the act of nictitation to clean or moisten it. 3. _Respiratio et Tussis irritativæ._ In the acts of respiration and of coughing there is an increased motion of the air-cells of the lungs owing to some stimulating cause, as described above in Class I. 1. 2. 8. and I. 1. 3. 4. and which are frequently performed without our attention or consciousness, and are then irritative actions; and thus differ from those described in Class II. 1. 1. 2. and 5. To these increased actions of the air-cells are superadded those of the intercostal muscles and diaphragm by irritative association. When any unnatural stimulus acts so violently on the organs of respiration as to induce pain, the sensorial power of sensation becomes added to that of irritation, and inflammation of the membranes of them is a general consequence. 4. _Exclusio bilis._ The exclusion of the bile from the gall-bladder, and its derivation into the duodenum, is an irritative action in consequence of the stimulus of the aliment on the extremity of the biliary duct, which terminates in the intestine. The increased secretion of tears is occasioned in a similar manner by any stimulating material in the eyes; which affects the excretory ducts of the lacrymal glands. A pain of the external membrane of the eye sometimes attends any unusual stimulus of it, then the sensorial power of sensation becomes added to that of irritation, and a superficial inflammation is induced. 5. _Dentitio._ Toothing. The pain of toothing often begins much earlier than is suspected; and is liable to produce convulsions; which are sometimes relieved, when the gum swells, and becomes inflamed; at other times a diarrhoea supervenes, which is generally esteemed a favourable circumstance, and seems to prevent the convulsions by supplying another means of relieving the pain of dentition by irritative exertion; and a consequent temporary exhaustion of sensorial power. See Class I. 1. 2. 5. Sect. XXXV. 2. 1. The convulsions from toothing generally commence long before the appearance of the teeth; but as the two middle incisors of the lower jaw generally appear first, and then those of the upper, it is adviseable to lance the gums over these longitudinally in respect to the jaw-bones, and quite down to the periosteum, and through it. As the convulsions attending the commencement of toothing are not only dangerous to life in their greatest degree, but are liable to induce stupor or insensibility by their continuance even in a less degree, the most efficacious means should be used to cure them. M. M. Lance the gum of the expected teeth quite through the periosteum longitudinally. Venesection by the lancet or by two or three leeches. One grain of calomel as a purge. Tincture of jalap, five or six drops in water every three hours til it purges, to be repeated daily. After evacuations a small blister on the back or behind the ears. And lastly, two or three drops of laudanum according to the age of the child. Warm bath. See Class III. 1. 1. 5. and 6. 6. _Priapismus chronicus._ I have seen two cases, where an erection of the penis, as hard as horn, continued two or three weeks without any venereal desires, but not without some pain; the easiest attitude of the patients was lying upon their backs with their knees up. At length the corpus cavernosum urethræ became soft, and in another day or two the whole subsided. In one of them a bougie was introduced, hoping to remove some bit of gravel from the caput gallinaginis, camphor, warm bathing, opium, lime-water, cold aspersion, bleeding in the veins of the penis, were tried in vain. One of them had been a free drinker, had much gutta rosacea on his face, and died suddenly a few months after his recovery from this complaint. Was it a paralysis of the terminations of the veins, which absorb the blood from the tumid penis? or from the stimulus of indurated semen in the seminal vessels? In the latter case some venereal desires should have attended. Class III. 1. 2. 16. The priapismus, which occurs to vigorous people in a morning before they awake, has been called the signum salutis, or banner of health, and is occasioned by the increase of our irritability or sensibility during sleep, as explained in Sect. XVIII. 15. 7. _Distentio mamularum._ The distention of the nipples of lactescent women is at first owing to the stimulus of the milk. See Sect. XIV. 8. and Sect. XVI. 5. See Class II. 1. 7. 10. 8. _Descensus uteri._ This is a very frequent complaint after bad labours, the fundus uteri becomes inverted and descends like the prolapsus ani. M. M. All the usual pessaries are very inconvenient and ineffectual. A piece of soft sponge about two inches diameter introduced into the vagina gives great ease to these patients, and supports the uterus; it should have a string put through it to retract it by. There are also pessaries now made of elastic gum, which are said to be easily worn, and to be convenient, from their having a perforation in their centre. 9. _Prolapsus ani._ The lower part of the rectum becomes inverted, and descends after every stool chiefly in children; and thus stimulates the sphincter ani like any other extraneous body. M. M. It should be dusted over with very fine powder of gum sandarach, and then replaced. Astringent fomentations; as an infusion of oak-bark, or a slight solution of alum. Horizontal rest frequently in the day. 10. _Lumbricus._ Round worm. The round worm is suspected in children when the belly is tumid, and the countenance bloated and pale, with swelling of the upper lip. The generation of these worms is promoted by the too dilute state of the bile, as is evident in the fleuke-worm found in the biliary ducts and substance of the liver in sheep; and in water-rats, in the livers of which last animals they were lately detected in large numbers by Dr. Capelle. Transactions of the college at Philadelphia, v. i. Now as the dilute state of the bile depends on the deficiency of the absorption of its thinner parts, it appears, that the tumid belly, and bloated countenance, and swelled upper lip, are a concomitant circumstance attending the general inactivity of the absorbent system; which is therefore to be esteemed the remote cause of the generation of worms. The simplicity of the structure of worms probably enables them to exist in more various temperatures of heat; and their being endued with life prevents them from being destroyed by digestion in the stomach, probably in the same manner as the powers of life prevent the fermentation and putrefaction of the stomach itself. Hence I conclude, that worms are originally taken into our alimentary canal from without; as I believe similar worms of all kinds are to be found out of the body. M. M. The round worm is destroyed by a cathartic with four or six grains of calomel; and afterwards by giving six or eight grains of filings of iron twice a day for a fortnight. See Hepatis tumor, Class I. 2. 3. 9. As worms are liable to come away in fevers, whether of the hectic or putrid kind, could they be removed by purulent matter, or rotten egg, or putrid flesh, since in those fevers from the enfeebled action of the intestines the fæces become highly putrid? 11. _Tænia._ Tape-worm consists of a chain of animals extending from the stomach to the anus. See Sect. XXXIX. 2. 3. It frequently exists in cats, rats, and geese, and probably in many other animals. The worms of this genus possess a wonderful power of retaining life. Two of them, which were voided by a pointer dog in consequence of violent purgatives, each of which were several feet in length, had boiling water poured on them in a bason; which seemed not much to inconvenience them. When the water was cool, they were taken out and put into gin or whiskey of the strongest kind, in which their life and activity continued unimpaired; and they were at length killed by adding to the spirit a quantity of corrosive sublimate. Medic. Comment. for 1791, p. 370. The tape-worm is cured by an amalgama of tin and quicksilver, such as is used on the back of looking-glasses; an ounce should be taken every two hours, till a pound is taken; and then a brisk cathartic of Glauber's salt two ounces, and common salts one ounce, dissolved in two wine pints of water, half a pint to be taken every hour till it purges. The worm extends from the stomach to the anus, and the amalgama tears it from the intestine by mechanical pressure, acting upon it the whole way. Electric shocks through the duodenum greatly assists the operation. Large doses of tin in powder. Iron filings in large doses. The powder of fern-root seems to be of no use, as recommended by M. Noufflier. 12. _Ascarides._ Thread-worms. These worms are said to be more frequent in some parts of this kingdom than in others, as near the fens of Lincolnshire. Do they escape from the body and become flies, like the bott-worm in horses? Do they crawl from one child to another in the same bed? Are they acquired from flies or worms, which are seen in putrid necessary houses, as these worms as well as the tapeworms, are probably acquired from without? this may account for their re-appearance a few weeks or months after they have been destroyed; or can this happen from the eggs or parts of them remaining? Ascarides appear to be of two kinds, the common small ones like a thread; which has a very sharp head, as appears in the microscope; and which is so tender, that the cold air soon renders it motionless; and a larger kind above an inch long, and nearly as thick as a very small crow-quill, and which is very hard in respect to its texture, and very tenacious of life. One of these last was brought to me, and was immediately immersed in a strong solution of sugar of lead, and lived in it a very long time without apparent inconvenience. M. M. Ascarides are said to be weakened by twenty grains of cinnabar and five of rhubarb taken every night, but not to be cured by this process. As these worms are found only in the rectum, variety of clysters have been recommended. I was informed of a case, where solutions of mercurial ointment were used as a clyster every night for a month without success. Clysters of Harrowgate water are recomended, either of the natural, or of the factitious, as described below, which might have a greater proportion of liver of sulphur in it. As the cold air soon destroys them, after they are voided, could clysters of iced water be used with advantage? or of spirit of wine and water? or of ether and water? Might not a piece of candle, about an inch long, or two such pieces, smeared with mercurial ointment, and introduced into the anus at night, or twice a day, be effectual by compressing their nidus, as well as by the poison of the mercury. The clysters should be large in quantity, that they may pass high in the rectum, as two drams of tobacco boiled a minute in a pint of water. Or perhaps what might be still more efficacious and less inconvenient, the smoke of tobacco injected by a proper apparatus every night, or alternate nights, for six or eight weeks. This was long since recommended, I think by Mr. Turner of Liverpool; and the reason it has not succeeded, I believe to have been owing to the imperfections of the joints of the common apparatus for injecting the smoke of tobacco, so that it did not pass into the intestine, though it was supposed to do so, as I once observed. The smoke should be received from the apparatus into a large bladder; and it may then be certainly injected like the common clyster with sufficient force; otherwise oiled leathers should be nicely put round the joints of the machine; and a wet cloth round the injecting pipe to prevent the return of the smoke by the sides of it. Clysters of carbonated hydrogen gas, or of other factitious airs, might be tried. Harrowgate water taken into the stomach, so as to induce six or seven stools every morning, for four or six weeks, is perhaps the most efficacious method in common use. A factitious Harrowgate water may be made probably of greater efficacy than the natural, by dissolving one ounce of marine salt, (called bay salt) and half an ounce of magnesia Glauber's salt, (called Epsom salt, or bitter purging salt) in twenty-eight ounces of water. A quarter or half a pint of this is to be taken every hour, or two hours in the morning, till it operates, with a tea-spoonful of a solution of liver of sulphur, which is to be made by putting an ounce of hepar sulphuris into half a pint of water. See Class IV. 1. 2. 9. 13. _Dracunculus._ A thin worm brought from the coast of Guinea. It is found in the interstices of the muscles, and is many yards long; it makes a small ulcer; which is cured by extracting an inch of the worm a day, and wrapping the extracted part slowly round a bit of tobacco pipe till next day, so as not to break it. I have twice seen long worms, like a thick horse-hair, in water in July in this country, which appeared hard and jointed. 14. _Morpiones._ Crab-lice. The excrement of this animal stains the linen, and appears like diluted blood. M. M. Spirit of wine. Mercurial ointment, shaving the part. Oil destroys other insects, if they be quite covered with it, as the ticks on dogs, and would probably therefore destroy these. Its manner of operation is by stopping up or filling their spiracula, or breathing pores; a few drops of oil poured on a wasp, so as to cover it, destroys it in a few seconds. 15. _Pediculi._ Lice. There is said to be a disease, in which these animals are propagated in indestructible numbers, so as to destroy the patient. M. M. Cleanliness, mercurial ointment, stavis acria in powder, or the tincture of it in spirit of wine. Spirit of wine alone? Bath of oil? * * * * * ORDO I. _Increased Irritation._ GENUS V. _With Increased Actions of the Organs of Sense._ SPECIES. 1. _Visus acrior._ Acuter sight. There have been instances of people, who could see better in the gloom of the evening, than in the stronger light of the day; like owls, and bats, and many quadrupeds, and flying insects. When the eye is inflamed, great light becomes eminently painful, owing to the increased irritative motions of the retina, and the consequent increased sensation. Thus when the eye is dazzled with sudden light, the pain is not owing to the motion of the iris; for it is the contraction of the iris, which relieves the pain from sudden light; but to the too violent contractions of the moving fibres, which constitute the extremities of the optic nerve. 2. _Auditus acrior._ The irritative ideas of hearing are so increased in energy as to excite our attention. This happens in some diseases of the epileptic kind, and in some fevers. Hence the whispering of the currents of air in a room, the respiration of the company, and noises before unperceived, become troublesome; and sounds louder than usual, or unexpected, produce starting, and convulsions. M. M. Put oil of almonds into the ears. Stop the meatus auditorius with cotton wool. Set the feet of the patient's bed on cushions, or suspend it by cords from the ceiling. 3. _Olfactus acrior._ The irritative ideas of smell from the increased action of the olfactive nerve excite our attention. Hence common odours are disagreeable; and are perceived from variety of objects, which were before thought inodorous. These are commonly believed to be hallucinations of the sense. M. M. Snuff starch up the nostrils. 4. _Gustus acrior._ The irritative ideas of taste, as of our own saliva, and even of the atmospheric air, excite our attention; and common tastes are disagreeably strong. M. M. Water. Mucilage. Vegetable acids. Scrape the tongue clean. Rub it with a sage-leaf and vinegar. 5. _Tactus acrior._ The irritative ideas of the nerves of touch excite our attention: hence our own pressure on the parts, we rest upon, becomes uneasy with universal soreness. M. M. Soft feather-bed. Combed wool put under the patients, which rolls under them, as they turn, and thus prevents their friction against the sheets. Drawers of soft leather. Plasters of cerate with calamy. 6. _Sensus caloris acrior._ Acuter sense of heat occurs in some diseases, and that even when the perceptible heat does not appear greater than natural to the hand of another person. See Class I. 1. 2. See Sect. XIV. 8. All the above increased actions of our organs of sense separately or jointly accompany some fevers, and some epileptic diseases; the patients complaining of the perception of the least light, noises in their ears, bad smells in the room, and bad tastes in their mouths, with soreness, numbness, and other uneasy feels, and with disagreeable sensations of general or partial heat. 7. _Sensus extensionis acrior._ Acuter sense of extension. The sense of extension was spoken of in Sect. XIV. 7. and XXXII. 4. The defect of distention in the arterial system is accompanied with faintness; and its excess with sensations of fulness, or weight, or pressure. This however refers only to the vascular muscles, which are distended by their appropriated fluids; but the longitudinal muscles are also affected by different quantities of extension, and become violently painful by the excess of it. These pains of muscles and of membranes are generally divided into acute and dull pains. The former are generally owing to increase of extension, as in pricking the skin with a needle; and the latter generally to defect of extension, as in cold head-aches; but if the edge of a knife, or point of a pin, be gradually pressed against the fibres of muscles or membranes, there would seem to be three states or stages of this extension of the fibres; which have acquired names according to the degree or kind of sensation produced by the extension of them; these are 1. titillation or tickling. 2. itching, and the 3. smarting; as described below. See Sect. XIV. 9. 8. _Titillatio._ Tickling is a pleasureable pain of the sense of extension above mentioned, and therefore excites laughter; as described in Sect. XXXIV. 1. 4. The tickling of the nostrils, which precedes the efforts of sneezing, is owing to the increased irritation occasioned by external stimulus; and is attended with a pleasureable sensation in consequence of the increased action of the part. When this action is exerted in a greater degree, the sensation becomes painful, and the convulsion of sneezing ensues; as the pain in tickling the soles of the feet of children is relieved by laughter. A lady after a bruise on her nose by a fall was affected with incessant sneezing, and relieved by snuffing starch up her nostrils. Perpetual sneezings in the measles, and in catarrhs from cold, are owing to the stimulus of the saline part of the mucous effusion on the membrane of the nostrils. See Class II. 1. 1. 3. 9. _Pruritus._ Itching seems to be a greater degree of titillation, and to be owing to the stimulus of some acrid material, as the matter of the itch; or of the herpes on the scrotum, and about the anus; or from those universal eruptions, which attend some elderly people, who have drank much vinous spirit. It occurs also, when inflammations are declining, as in the healing of blisters, or in the cure of ophthalmia, as the action of the vessels is yet so great as to produce sensation; which, like the titillations that occasion laughter, is perpetually changing from pleasure to pain. When the natural efforts of scratching do not relieve the pain of itching, it sometimes increases so as to induce convulsions and madness. As in the furor uterinus, and satyriasis, and in the sphincter ani and scrotum. See Class II. 1. 4. 14. IV. 2. 2. 6. M. M. Warm bath. Fomentation. Alcohol externally. Poultice. Oiled silk. Mercurial ointments on small surfaces at once. See Class II. 1. 4. 12. Solutions of lead on small surfaces at once. 10. _Dolor urens._ Smarting follows the edge of a knife in making a wound, and seems to be owing to the distention of a part of a fibre, till it breaks. A smarting of the skin is liable to affect the scars left by herpes or shingles; and the callous parts of the bottoms of the feet; and around the bases of corns on the toes; and frequently extends after sciatica along the outside of the thigh, and of the leg, and part of the foot. All these may be owing to the stimulus of extension, by blood or serum being forced into vessels nearly coalesced. M. M. Emplastrum de minio put like a bandage on the part. Warm fomentation. Oil and camphor rubbed on the part. Oil-silk covering. A blister on the part. Ether, or alcohol, suffered to evaporate on the part. 11. _Consternatio._ Surprise. As our eyes acquaint us at the same time with less than half of the objects, which surround us, we have learned to confide much in the organ of hearing to warn us of approaching dangers. Hence it happens, that if any sound strikes us, which we cannot immediately account for, our fears are instantly alarmed. Thus in great debility of body, the loud clapping of a door, or the fall of a fire-shovel, produces alarm, and sometimes even convulsions; the same occurs from unexpected sights, and in the dark from unexpected objects of touch. In these cases the irritability is less than natural, though it is erroneously supposed to be greater; and the mind is busied in exciting a train of ideas inattentive to external objects; when this train of ideas is dissevered by any unexpected stimulus, surprise is excited; as explained in Sect. XVII. 3. 7. and XVIII. 17. then as the sensibility in these cases is greater, fear becomes superadded to the surprise; and convulsions in consequence of the pain of fear. See Sect. XIX. 2. The proximate cause of surprise is the increased irritation induced by some violent stimulus, which dissevers our usual trains of ideas; but in diseases of inirritability the frequent starting or surprise from sounds not uncommon, but rather louder than usual, as the clapping of a door, shews, that the attention of the patient to a train of sensitive ideas was previously stronger than natural, and indicates an incipient delirium; which is therefore worth attending to in febrile diseases. * * * * * ORDO II. _Decreased Irritation._ GENUS I. _With decreased Action of the Sanguiferous System._ The reader should be here apprized, that the words strength and debility, when applied to animal motions, may properly express the quantity of resistance such motions may overcome; but that, when they are applied to mean the susceptibility or insusceptibility of animal fibres to motion, they become metaphorical terms; as in Sect. XII. 2. 1. and would be better expressed by the words activity and inactivity. There are three sources of animal inactivity; first, the defect of the natural quantity of stimulus on those fibres, which have been accustomed to perpetual stimulus; as the arterial and secerning systems. When their accustomed stimulus is for a while intermitted, as when snow is applied to the skin of the hands, an accumulation of sensorial power is produced; and then a degree of stimulus, as of heat, somewhat greater than that at present applied, though much less than the natural quantity, excites the vessels of the skin into violent action. We must observe, that a deficiency of stimulus in those fibres, which are not subject to perpetual stimulus, as the locomotive muscles, is not succeeded by accumulation of sensorial power; these therefore are more liable to become permanently inactive after a diminution of stimulus; as in strokes of the palsy, this may be called inactivity from defect of stimulus. 2. A second source of animal inactivity exists, when the sensorial power in any part of the system has been previously exhausted by violent stimuli; as the eyes after long exposure to great light; or the stomach, to repeated spirituous potation; this may be termed inactivity from exhaustion of sensorial power. See Sect. XII. 2. 1. 3. But there is a third source of inactivity owing to the deficient production of sensorial power in the brain; and hence stimuli stronger than natural are required to produce the accustomed motions of the arterial system; in this case there is no accumulation of sensorial power produced; as in the inactivity owing to defect of stimulus; nor any previous exhaustion of it, as in the inactivity owing to excess of stimulus. This third kind of inactivity causes many of the diseases of this genus; which are therefore in general to be remedied by such medicines as promote a greater production of sensorial power in the brain; as the incitantia, consisting of wine, beer, and opium, in small repeated quantities; and secondly of such as simply stimulate the arterial and glandular system into their natural actions; as small repeated blisters, spices, and essential oils. And lastly the sorbentia, which contribute to supply the more permanent strength of the system, by promoting the absorption of nourishment from the stomach, and intestines; and of the superfluous fluid, which attends the secretions. SPECIES. 1. _Febris inirritativa._ Inirritative fever. This is the typhus mitior, or nervous fever of some writers; it is attended with weak pulse without inflammation, or symptoms of putridity, as they have been called. When the production of sensorial power in the brain is less than usual, the pulse becomes quick as well as weak; and the heart sometimes trembles like the limbs of old age, or of enfeebled drunkards; and when this force of the contractions of the heart and arteries is diminished, the blood is pushed on with less energy, as well as in less quantity, and thence its stimulus on their sides is diminished in a duplicate ratio. In compressions of the brain, as in apoplexy, the pulse becomes slower and fuller; for in that disease, as in natural sleep, the irritative motions of the heart and arteries are not diminished, volition alone is suspended or destroyed. If the absorption of the terminations of the veins is not equally impaired with the force of the heart and arteries, the blood is taken up by the veins the instant it arrives at their extremities; the capillary vessels are left empty, and there is less resistance to the current of the blood from the arteries; hence the pulse becomes empty, as well as weak and quick; the veins of the skin are fuller than the arteries of it; and its appearance becomes pale, bluish, and shrunk. See Class II. 1. 3. 1. When this pulse persists many hours, it constitutes the febris inirritativa, or typhus, or nervous fever, of some writers; it is attended with little heat, the urine is generally of a natural colour, though in less quantity; with great prostration of strength, and much disturbance of the faculties of the mind. Its immediate cause seems to be a deficient secretion of the sensorial power from the inaction of the brain; hence almost the whole of the sensorial power is expended in the performance of the motions necessary to life, and little of it can be spared for the voluntary actions of the locomotive muscles, or organs of sense, see Class I. 2. 5. 3. Its more remote cause may be from a paralysis or death of some other part of the body; as of the spleen, when a tumour is felt on the left side, as in some intermittents; or of the kidnies, when the urine continues pale and in small quantity. Does the revivescence of these affected parts, or their torpor, recurring at intervals, form the paroxysms of these fevers? and their permanent revivescence establish the cure? See Class IV. 2. 1. 19. M. M. Wine and opium in small quantities repeated every three hours alternately; small repeated blisters; warm but fresh air; sorbentia; nutrientia; transfusion of blood. Small electric shocks passed through the brain in all directions. Oxygene air? 2. _Paresis inirritativa._ Inirritative debility. A defective action of the irritative motions without increase of the frequency of the pulse. It continues three or four weeks like a fever, and then either terminates in health, or the patient sinks into one kind of apoplexy, and perishes. Many symptoms, which attend inirritative fevers, accompany this disease, as cold hands and feet at periodic times, scurf on the tongue, want of appetite, muddy urine, with pains of the head, and sometimes vertigo, and vomiting. This disease differs from the inirritative fever by the pulse not being more frequent than in health. The want of appetite and of digestion is a principal symptom, and probably is the cause of the universal debility, which may be occasioned by the want of nourishment. The vertigo is a symptom of inirritability, as shewn in Class IV. 2. 1. 16. the muddy urine is owing to increased absorption from the bladder in consequence of the diminished cutaneous and cellular absorption, as in anasarca, explained in Sect. XXIX. 5. 1. and is therefore a consequence of the inirritability of that part of the system; the foul tongue is owing to an increased absorption of the thinner part of the mucus in consequence of the general deficiency of fluid, which should be absorbed by the skin and stomach. The sickness is owing to decreased action of the stomach, which is probably the primary disease, and is connected with the vertigo. M. M. An emetic. Calomel, grains iv. once or twice. Then a blister. Peruvian bark. Valerian. Columbo. Steel. Opium and wine in small quantities, repeated alternately every three hours. Small electric percussions through the stomach. 3. _Somnus interruptus._ Interrupted sleep. In some fevers, where the inirritability is very great, when the patient falls asleep, the pulse in a few minutes becomes irregular, and the patient awakes in great disorder, and fear of dying, refusing to sleep again from the terror of this uneasy sensation. In this extreme debility there is reason to believe, that some voluntary power during our waking hours is employed to aid the irritative stimuli in carrying on the circulation of the blood through the lungs; in the same manner as we use voluntary exertions, when we listen to weak sounds, or wish to view an object by a small light; in sleep volition is suspended, and the deficient irritation alone is not sufficient to carry on the pulmonary circulation. This explanation seems the most probable one, because in cases of apoplexy the irritative motions of the arterial system do not seem to be impaired, nor in common sleep. See Incubus III. 2. 1. 13. M. M. Opium in very small doses, as three drops of laudanum. A person should watch the patient, and awaken him frequently; or he should measure the time between slumber and slumber by a stop-watch, and awaken the patient a little before he would otherwise awake; or he should keep his finger on the pulse, and should forcibly awaken him, as soon as it becomes irregular, before the disorder of the circulation becomes so great as to disturb him. See Class I. 2. 1. 9. and Sect. XXVII. 2. 4. _Syncope._ Fainting consists in the decreased action of the arterial system; which is sometimes occasioned by defect of the stimulus of distention, as after venesection, or tapping for the dropsy. At other times it arises from great emotions of the mind, as in sudden joy or grief. In these cases the whole sensorial power is exerted on these interesting ideas, and becomes exhausted. Thus during great surprise or fear the heart stops for a time, and then proceeds with throbbing and agitation; and sometimes the vital motions become so deranged, as never to recover their natural successive action; as when children have been frightened into convulsions. See Sect. XII. 7. 1. Miss ----, a young lady of Stafford, in travelling in a chaise was so affected by seeing the fall of a horse and postillion, in going down a hill, though the carriage was not overturned, that she fainted away, and then became convulsed, and never spoke afterwards; though she lived about three days in successive convulsions and stupor. 5. _Hæmorrhagia venosa._ A bleeding from the capillaries arising from defect of venous absorption, as in some of those fevers commonly termed putrid. When the blood stagnates in the cellular membrane, it produces petechiæ from this torpor or paralysis of the absorbent mouths of the veins. It must be observed, that those people who have diseased livers, are more liable to this kind of hæmorrhages, as well as to the hæmorrhagia arteriosa; the former, because patients with diseased livers are more subject to paralytic complaints in general, as to hemiplegia, and to dropsy, which is a paralysis of the lymphatics; and the latter is probably owing to the delay of the circulation in the vena porta by the torpor of this hepatic vessel, when the liver is not much enlarged; and to its pressure on the vena cava, when it is much enlarged. M. M. Vitriolic acid, opium, steel, bark. Sponge bound on the part. Steel dissolved in spirit of wine externally. Flour. 6. _Hæmorrhois cruenta._ In the bleeding piles the capillary vessels of the rectum become distended and painful from the defect of the venous absorption of the part, and at length burst; or the mucous glands are so dilated as to give a passage to the blood; it is said to observe lunar periods. M. M. Venesection, poultices, cathartics, spice, cold bath, and sorbentia. External compression by applying lint, sponge, or cotton. Internal compression by applying a bit of candle smeared with mercurial ointment. Strangulate the tumid piles with a silk string. Cut them off. See Class I. 2. 3. 22. Mrs. ---- had for twelve or fifteen years, at intervals of a year or less, a bleeding from the rectum without pain; which however stopped spontaneously after she became weakened, or by the use of injections of brandy and water. Lately the bleeding continued above two months, in the quantity of many ounces a day, till she became pale and feeble to an alarming degree. Injections of solutions of lead, of bark and salt of steel, and of turpentine, with some internal astringents, and opiates, were used in vain. An injection of the smoke of tobacco, with ten grains of opium mixed with the tobacco, was used, but without effect the two first times on account of the imperfection of the machine; on the third time it produced great sickness, and vertigo, and nearly a fainting fit; from which time the blood entirely stopped. Was this owing to a fungous excrescence in the rectum; or to a blood-vessel being burst from the difficulty of the blood passing through the vena porta from some hepatic obstruction, and which had continued to bleed so long? Was it stopped at last by the fainting fit? or by the stimulus of the tobacco? 7. _Hæmorrhagia renum._ Hæmorrhage from the kidnies, when attended with no pain, is owing to defect of venous absorption in the kidney. When attended with pain on motion, it is owing to a bit of gravel in the ureter or pelvis of the kidney; which is a much more frequent disease than the former. See Sect. XXVII. 1. M. M. 1. Venesection in small quantity, calomel, bark, steel, an opiate; cold immersion up to the navel, the upper part of the body being kept cloathed. Neville-Holt water. 2. Alcalized water aerated. Much diluent liquids. Cool dress. Cool bed-room. Cows are much subject to bloody urine, called foul water by the farmers; in this disease about sixty grains of opium with or without as much rust of iron, given twice a day, in a ball mixed with flour and water, or dissolved in warm water, or warm ale, is, I believe, an efficacious remedy, to which however should be added about two quarts of barley or oats twice a day, and a cover at night, if the weather be cold. 8. _Hæmorrhagia Hepatis._ Hæmorrhage from the liver. It sometimes happens in those, who have the gutta rosea, or paralytic affections owing to diseased livers induced by the potation of fermented liquors, that a great discharge of black viscid blood occasionally comes away by stool, and sometimes by vomiting: this the ancients called Melancholia, black bile. If it was bile, a small quantity of it would become yellow or green on dilution with warm water, which was not the case in one experiment which I tried; it must remain some time in the intestines from its black colour, when it passes downwards, and probably comes from the bile-ducts, and is often a fatal symptom. When it is evacuated by vomiting it is less dangerous, because it shews greater remaining irritability of the intestinal canal, and is sometimes salutary to those who have diseased livers. M. M. An emetic. Rhubarb, steel, wine, bark. 9. _Hæmoptoe venosa._ Venous hæmoptoe frequently attends the beginning of the hereditary consumptions of dark-eyed people; and in others, whose lungs have too little irritability. These spittings of blood are generally in very small quantity, as a tea-spoonful; and return at first periodically, as about once a month; and are less dangerous in the female than in the male sex; as in the former they are often relieved by the natural periods of the menses. Many of these patients are attacked with this pulmonary hæmorrhage in their first sleep; because in feeble people the power of volition is necessary, besides that of irritation, to carry on respiration perfectly; but, as volition is suspended during sleep, a part of the blood is delayed in the vessels of the lungs, and in consequence effused, and the patient awakes from the disagreeable sensation. See Class I. 2. 1. 3. II. 1. 6. 6. III. 2. 1. 10. M. M. Wake the patient every two or three hours by an alarum clock. Give half a grain of opium at going to bed, or twice a day. Onions, garlic, slight chalybeates. Issues. Leeches applied once a fortnight or month to the hemorrhoidal veins to produce a new habit. Emetics after each period of hæmoptoe, to promote expectoration, and dislodge any effused blood, which might by remaining in the lungs produce ulcers by its putridity. A hard bed, to prevent too sound sleep. A periodical emetic or cathartic once a fortnight. 10. _Palpitatio cordis._ The palpitation of the heart frequently attends the hæmoptoe above mentioned; and consists in an ineffectual exertion of the heart to push forwards its contents in due time, and with due force. The remote cause is frequently some impediment to the general circulation; as the torpor of the capillaries in cold paroxysms of fever, or great adhesions of the lungs. At other times it arises from the debility of the action of the heart owing to the deficient sensorial power of irritation or of association, as at the approach of death. In both these cases of weak exertion the heart feels large to the touch, as it does not completely empty itself at each contraction; and on that account contracts more frequently, as described in Sect. XXXII. 2. 2. Another kind of palpitation may sometimes arise from the retrograde motions of the heart, as in fear. See Class I. 3. 1. 2. and IV. 3. 1. 6. 11. _Menorrhagia._ Continued flow of the catamenia. The monthly effusion of blood from the uterus or vagina is owing to a torpor of the veins of those membranes in consequence of the defect of venereal stimulus; and in this respect resembles the mucus discharged in the periodical venereal orgasm of the female quadrupeds, which are secluded from the males. The menorrhagia, or continued flow of this discharge, is owing to a continued defect of the venous absorption of the membranes of the uterus or vagina. See Class IV. 2. 4. 7. M. M. Venesection in small quantity. A cathartic. Then opium, a grain every night. Steel. Bark. A blister. Topical aspersion with cold water, or cold vinegar. 12. _Dysmenorrhagia._ A difficulty of menstruation attended with pain. In this complaint the torpor of the uterine vessels, which precedes menstruation, is by sympathy accompanied with a torpor of the lumbar membranes, and consequent pain; and frequently with cold extremities, and general debility. The small quantity and difficulty of the discharge is owing to arterial inactivity, as in chlorosis. Whence it happens, that chalybeate medicines are of efficacy both to stop or prevent too great menstruation, and to promote or increase deficient menstruation; as the former is owing to inirritability of the veins, and the latter of the arteries of the uterus. See Article IV. 2. 6. in the Materia Medica. M. M. Opium, steel, pediluvium. Warm bath. 13. _Lochia nimia._ Too great discharge after delivery. In that unnatural practice of some hasty accoucheurs of introducing the hand into the uterus immediately after the delivery of the child, and forcibly bringing away the placenta, it frequently happens, that a part of it is left behind; and the uterus, not having power to exclude so small a portion of it, is prevented from complete contraction, and a great hæmorrhage ensues. In this circumstance a bandage with a thick compress on the lower part of the belly, by appressing the sides of the uterus on the remaining part of the placenta, is likely to check the hæmorrhage, like the application of a pledget of any soft substance on a bleeding vessel. In other cases the lochia continues too long, or in too great quantity, owing to the deficiency of venous absorption. M. M. An enema. An opiate. A blister. Slight chalybeates. Peruvian bark. Clothes dipped in cold vinegar and applied externally. Bandages on the limbs to keep more blood in them for a time have been recommended. 14. _Abortio spontanea._ Some delicate ladies are perpetually liable to spontaneous abortion, before the third, or after the seventh, month of gestation. From some of these patients I have learnt, that they have awakened with a slight degree of difficult respiration, so as to induce them to rise hastily up in bed; and have hence suspected, that this was a tendency to a kind of asthma, owing to a deficient absorption of blood in the extremities of the pulmonary or bronchial veins; and have concluded from thence, that there was generally a deficiency of venous absorption; and that this was the occasion of their frequent abortion. Which is further countenanced, where a great sanguinary discharge precedes or follows the exclusion of the fetus. M. M. Opium, bark, chalybeates in small quantity. Change to a warmer climate. I have directed with success in four cases half a grain of opium twice a day for a fortnight, and then a whole grain twice a day during the whole gestation. One of these patients took besides twenty grains of Peruvian bark for several weeks. By these means being exactly and regularly persisted in, a new habit became established, and the usual miscarriages were prevented. Miscarriages more frequently happen from eruptive fevers, and from rheumatic ones, than from other inflammatory diseases. I saw a most violent pleurisy and hepatitis cured by repeated venesection about a week or ten days before parturition; yet another lady whom I attended, miscarried at the end of the chicken pox, with which her children were at the same time affected. Miscarriages towards the termination of the small pox are very frequent, yet there have been a few instances of children, who have been born with the eruption on them. The blood in the small pox will not inoculate that disease, if taken before the commencement of the secondary fever; as shewn in Sect. XXXIII. 2. 10. because the contagious matter is not yet formed, but after it has been oxygenated through the cuticle in the pustules, it becomes contagious; and if it be then absorbed, as in the secondary fever, the blood of the mother may become contagious, and infect the child. The same mode of reasoning is applicable to the chicken pox. See Class IV. 3. 1. 7. 15. _Scorbutus._ Sea-scurvy is caused by salt diet, the perpetual stimulus of which debilitates the venous and absorbent systems. Hence the blood is imperfectly taken up by the veins from the capillaries, whence brown and black spots appear upon the skin without fever. The limbs become livid and edematous, and lastly ulcers are produced from deficient absorption. See Sect. XXXIII. 3. 2. and Class II. 1. 4. 13. For an account of the scurvy of the lungs, see Sect. XXVII. 2. M. M. Fresh animal and vegetable food. Infusion of malt. New beer. Sugar. Wine. Steel. Bark. Sorbentia. Opium? 16. _Vibices._ Extravasations of blood become black from their being secluded from the air. The extravasation of blood in bruises, or in some fevers, or after death in some patients, especially in the parts which were exposed to pressure, is owing to the fine terminations of the veins having been mechanically compressed so as to prevent their absorbing the blood from the capillaries, or to their inactivity from disease. The blood when extravasated undergoes a chemical change before it is sufficiently fluid to be taken up by the lymphatic absorbents, and in that process changes its colour to green and then yellow. 17. _Petechiæ._ Purple spots. These attend fevers with great venous inirritability, and are probably formed by the inability of a single termination of a vein, whence the corresponding capillary becomes ruptured, and effuses the blood into the cellular membrane round the inert termination of the vein. This is generally esteemed a sign of the putrid state of the blood, or that state contrary to the inflammatory one. As it attends some inflammatory diseases which are attended with great inirritability, as in the confluent small pox. But it also attends the scurvy, where no fever exists, and it therefore simply announces the inactivity of the terminations of some veins; and is thence indeed a bad symptom in fevers, as a mark of approaching inactivity of the whole sanguiferous system, or death. The blue colour of some children's arms or faces in very cold weather is owing in like manner to the torpor of the absorbent terminations of the veins, whence the blood is accumulated in them, and sometimes bursts them. * * * * * ORDO II. _Decreased Irritation._ GENUS II. _Decreased Action of the Secerning System._ These are always attended with decrease of partial, or of general heat; for as the heat of animal bodies is the consequence of their various secretions, and is perpetually passing away into the ambient air, or other bodies in contact with them; when these secretions become diminished, or cease, the heat of the part or of the whole is soon diminished, or ceases along with them. SPECIES. 1. _Frigus febrile._ Febrile coldness. There is reason to believe, that the beginning of many fever-fits originates in the quiescence of some part of the absorbent system, especially where they have been owing to external cold; but that, where the coldness of the body is not owing to a diminution of external heat, it arises from the inaction of some part of the secerning system. Hence some parts of the body are hot whilst other parts are cold; which I suppose gave occasion to error in Martyn's Experiments; where he says, that the body is as hot in the cold paroxysms of fevers as at other times. After the sensorial power has been much diminished by great preceding activity of the system, as by long continued external heat, or violent exercise, a sudden exposure to much cold produces a torpor both greater in degree and over a greater portion of the system, by subtracting their accustomed stimulus from parts already much deprived of their irritability. Dr. Franklin in a letter to M. Duberge, the French translator of his works, mentions an instance of four young men, who bathed in a cold spring after a day's harvest work; of whom two died on the spot, a third on the next morning, and the other survived with difficulty. Hence it would appear, that those, who have to travel in intensely cold weather, will sooner perish, who have previously heated themselves much with drams, than those who have only the stimulus of natural food; of which I have heard one well attested instance. See Article VII. 2. 3. Class III. 2. 1. 17. _Frigus chronicum._ Permanent coldness. Coldness of the extremities, without fever, with dry pale skin, is a symptom of general debility, owing to the decreased action of the arterial system, and of the capillary vessels; whence the perspirable matter is secreted in less quantity, and in consequence the skin is less warm. This coldness is observable at the extremities of the limbs, ears, and nose, more than in any other parts: as a larger surface is here exposed to the contact of the air, or clothes, and thence the heat is more hastily carried away. The pain, which accompanies the coldness of the skin, is owing to the deficient exertion of the subcutaneous vessels, and probably to the accumulation of sensorial power in the extremities of their nerves. See Sect. XII. 5. 3. XIV. 6. XXXII. 3. and Class I. 2. 4. 1. M. M. A blister. Incitantia, nutrientia, sorbentia. Exercise. Clothes. Fire. Joy. Anger. 2. _Pallor fugitivus._ The fugitive paleness, which accompanies the coldness of the extremities, is owing to a less quantity of blood passing through the capillaries of the skin in a given time; where the absorbent power of the veins is at the same time much diminished, a part of the blood lingers at their junction with the capillary arteries, and a bluish tinge is mixed with the paleness; as is seen in the loose skin under the eye-lids, and is always a mark of temporary debility. See Class II. 1. 4. 4. Where the paleness of the skin is owing to the deficiency of red globules in the blood, it is joined with a yellowish tinge; which is the colour of the serum, with which the blood then abounds, as in chlorosis, and in torpor or paralysis of the liver, and is often mistaken for a superabundance of bile. A permanent paleness of the skin is owing to the coalescence of the minute arteries, as in old age. See Class I. 2. 2. 9. There is another source of paleness from the increased absorption of the terminations of the veins, as when vinegar is applied to the lips. See Sect. XXVII. 1. and another from the retrograde motions of the capillaries and fine extremities of the arteries. See Class II. 3. 1. 1. M. M. A blister, nutrientia, incitantia, exercise, oxygene gas. 3. _Pus parcius._ Diminished pus. Dryness of ulcers. In the cold fits of fever all the secretions are diminished, whether natural or artificial, as their quantity depends on the actions of the glands or capillaries, which then share in the universal inaction of the system. Hence the dryness of issues and blisters in great debility, and before the approach of death, is owing to deficient secretion, and not to increased absorption. M. M. Opium, wine in very small quantities, Peruvian bark. 4. _Mucus parcior._ Diminished mucus. Dryness of the mouth and nostrils. This also occurs in the cold fits of intermittents. In these cases I have also found the tongue cold to the touch of the finger, and the breath to the back of one's hand, when opposed to it, which are very inauspicious symptoms, and generally fatal. In fevers with inirritability it is generally esteemed a good symptom, when the nostrils and tongue become moist after having been previously dry; as it shews an increased action of the mucous glands of those membranes, which were before torpid. And the contrary to this is the facies Hippocratica, or countenance so well described by Hippocrates, which is pale, cold, and shrunk; all which are owing to the inactivity of the secerning vessels, the paleness from there being less red blood passing through the capillaries, the coldness of the skin from there being less secretion of perspirable matter, and the shrunk appearance from there being less mucus secreted into the cells of the cellular membrane. See Class IV. 2. 4. 11. M. M. Blisters. Incitantia. 5. _Urina parcior pallida._ Paucity of pale urine, as in the cold fits of intermittents; it appears in some nervous fevers throughout the whole disease, and seems to proceed from a palsy of the kidnies; which probably was the cause of the fever, as the fever sometimes ceases, when that symptom is removed: hence the straw-coloured urine in this fever is so far salutary, as it shews the unimpaired action of the kidnies. M. M. Balsams, essential oil, asparagus, rhubarb, a blister. Cantharides internally. 6. _Torpor hepaticus._ Paucity of bile from a partial inaction of the liver; hence the bombycinous colour of the skin, grey stools, urine not yellow, indigestion, debility, followed by tympany, dropsy, and death. This paralysis or inirritability of the liver often destroys those who have been long habituated to much fermented liquor, and have suddenly omitted the use of it. It also destroys plumbers, and house-painters, and in them seems a substitute for the colica saturnina. See Sect. XXX. M. M. Aloe and calomel, then the bark, and chalybeates. Mercurial ointment rubbed on the region of the liver. Rhubarb, three or four grains, with opium half a grain to a grain twice a day. Equitation, warm bath for half an hour everyday. 7. _Torpor Pancreatis._ Torpor of the pancreas. I saw what I conjectured to be a tumour of the pancreas with indigestion, and which terminated in the death of the patient. He had been for many years a great consumer of tobacco, insomuch that he chewed that noxious drug all the morning, and smoaked it all the afternoon. As the secretion from the pancreas resembles saliva in its general appearance, and probably in its office of assisting digestion, by preventing the fermentation of the aliment; as would appear by the experiments of Pringle and Macbride; there is reason to suspect, that a sympathy may exist between the salivary and pancreatic glands; and that the perpetual stimulus of the former by tobacco might in process of time injure the latter. See Tobacco, Article III. 2. 2. 8. _Torpor renis._ Inirritability or paralysis of the kidnies is probably frequently mistaken for gravel in them. Several, who have lived rather intemperately in respect to fermented or spirituous liquors, become suddenly seized about the age of sixty, or later, with a total stoppage of urine; though they have previously had no symptoms of gravel. In these cases there is no water in the bladder; as is known by the introduction of the catheter, of which those made of elastic gum are said to be preferable to metallic ones; or it may generally be known by the shape of the abdomen, either by the eye or hand. Bougies and catheters of elastic gum are sold at N^o 37, Red Lion-street, Holborn, London. M. M. Electric shocks, warm bath. Emetics. See calculus renis, Class I. 1. 3. 9. When no gravel has been previously observed, and the patient has been a wine-drinker rather than an ale-drinker, the case is generally owing to inirritability of the tubuli uriniferi, and is frequently fatal. See Class I. 2. 4. 20. 9. _Punctæ mucosæ vultûs._ Mucous spots on the face. These are owing to the inactivity of the excretory ducts of the mucous glands; the thinner part of this secretion exhales, and the remainder becomes inspissated, and lodges in the duct; the extremity of which becomes black by exposure to the air. M. M. They may be pressed out by the finger-nails. Warm water. Ether frequently applied. Blister on the part? 10. _Maculæ cutis fulvæ._ Morphew or freckles. Tawny blotches on the skin of the face and arms of elderly people, and frequently on their legs after slight erysipelas. The freckles on the face of younger people, who have red hair, seem to be a similar production, and seem all to be caused by the coalescence of the minute arteries or capillaries of the part. In a scar after a wound the integument is only opake; but in these blotches, which are called morphew and freckles, the small vessels seem to have become inactive with some of the serum of the blood stagnating in them, from whence their colour. See Class III. 1. 2. 12. M. M. Warm bathing. A blister on the part? 11. _Canities._ Grey hair. In the injection of the vessels of animals for the purposes of anatomical preparations, the colour of the injected fluid will not pass into many very minute vessels; which nevertheless uncoloured water, or spirits, or quicksilver will permeate. The same occurs in the filtration of some coloured fluids through paper, or very fine sand, where the colouring matter is not perfectly dissolved, but only diffused through the liquid. This has led some to imagine, that the cause of the whiteness of the hair in elderly people may arise from the diminution, or greater tenuity, of the glandular vessels, which secrete the mucus, which hardens into hair; and that the same difference of the tenuity of the secerning vessels may possibly make the difference of colour of the silk from different silk-worms, which is of all shades from yellow to white. But as the secreted fluids are not the consequence of mechanical filtration, but of animal selection; we must look out for another cause, which must be found in the decreasing activity of the glands, as we advance in life; and which affects many of our other secretions as well as that of the mucus, which forms the hair. Hence grey hairs are produced on the faces of horses by whatever injures the glands at their roots, as by corrosive blisters; and frequently on the human subject by external injuries on the head; and sometimes by fevers. And as the grey colour of hair consists in its want of transparency, like water converted into snow; there is reason to suppose, that a defect of secreted moisture simply may be the cause of this kind of opacity, as explained in Cataracta, Class I. 2. 2. 13. M. M. Whatever prevents the inirritability and insensibility of the system, that is, whatever prevents the approach of old age, will so far counteract the production of grey hairs, which is a symptom of it. For this purpose in people, who are not corpulent, and perhaps in those who are so, the warm bath twice or thrice a week is particularly serviceable. See Sect. XXXIX. 5. 1. on the colours of animals, and Class I. 1. 2. 15. 12. _Callus._ The callous skin on the hands and feet of laborious people is owing to the extreme vessels coalescing from the perpetual pressure they are exposed to. As we advance in life, the finer arteries lose their power of action, and their sides grow together; hence the paleness of the skins of elderly people, and the loss of that bloom, which is owing to the numerous fine arteries, and the transparency of the skin, that encloses them. M. M. Warm bath. Paring the thick skin with a knife. Smoothing it with a pumice stone. Cover the part with oiled silk to prevent the evaporation of the perspirable matter, and thus to keep it moist. 13. _Cataracta_ is an opacity of the crystalline lens of the eye. It is a disease of light-coloured eyes, as the gutta serena is of dark ones. On cutting off with scissars the cornea of a calf's eye, and holding it in the palm of one's hand, so as to gain a proper light, the artery, which supplies nutriment to the crystalline humour, is easily and beautifully seen; as it rises from the centre of the optic nerve through the vitreous humour to the crystalline. It is this point, where the artery enters the eye through the cineritious part of the optic nerve, (which is in part near the middle of the nerve,) which is without sensibility to light; as is shewn by fixing three papers, each of them about half an inch in diameter, against a wall about a foot distant from each other, about the height of the eye; and then looking at the middle one, with one eye, and retreating till you lose sight of one of the external papers. Now as the animal grows older, the artery becomes less visible, and perhaps carries only a transparent fluid, and at length in some subjects I suppose ceases to be pervious; then it follows, that the crystalline lens, losing some fluid, and gaining none, becomes dry, and in consequence opake; for the same reason, that wet or oiled paper is more transparent than when it is dry, as explained in Class I. 1. 4. 1. The want of moisture in the cornea of old people, when the exhalation becomes greater than the supply, is the cause of its want of transparency; and which like the crystalline gains rather a milky opacity. The same analogy may be used to explain the whiteness of the hair of old people, which loses its pellucidity along with its moisture. See Class I. 2. 2. 11. M. M. Small electric shocks through the eye. A quarter of a grain of corrosive sublimate of mercury dissolved in brandy, or taken in a pill, twice a day for six weeks. Couching by depression, or by extraction. The former of these operations is much to be preferred to the latter, though the latter is at this time so fashionable, that a surgeon is almost compelled to use it, lest he should not be thought an expert operator. For depressing the cataract is attended with no pain, no danger, no confinement, and may be as readily repeated, if the crystalline should rise again to the centre of the eye. The extraction of the cataract is attended with considerable pain, with long confinement, generally with fever, always with inflammation, and frequently with irreparable injury to the iris, and consequent danger to the whole eye. Yet has this operation of extraction been trumpeted into universal fashion for no other reason but because it is difficult to perform, and therefore keeps the business in the hands of a few empyrics, who receive larger rewards, regardless of the hazard, which is encountered by the flattered patient. A friend of mine returned yesterday from London after an absence of many weeks; he had a cataract in a proper state for the operation, and in spite of my earnest exhortation to the contrary, was prevailed upon to have it extracted rather than depressed. He was confined to his bed three weeks after the operation, and is now returned with the iris adhering on one side so as to make an oblong aperture; and which is nearly, if not totally, without contraction, and thus greatly impedes the little vision, which he possesses. Whereas I saw some patients couched by depression many years ago by a then celebrated empyric, Chevalier Taylor, who were not confined above a day or two, that the eye might gradually be accustomed to light, and who saw as well as by extraction, perhaps better, without either pain, or inflammation, or any hazard of losing the eye. As the inflammation of the iris is probably owing to forcing the crystalline through the aperture of it in the operation of extracting it, could it not be done more safely by making the opening behind the iris and ciliary process into the vitreous humour? but the operation would still be more painful, more dangerous, and not more useful than that by depressing it. 14. _Innutritio ossium._ Innutrition of the bones. Not only the blood effused in vibices and petechiæ, or from bruises, as well as the blood and new vessels in inflamed parts, are reabsorbed by the increased action of the lymphatics; but the harder materials, which constitute the fangs of the first set of teeth, and the ends of exfoliating bones, and sometimes the matter of chalk-stones in the gout, the coagulable lymph, which is deposited on the lungs, or on the muscles after inflammation of those parts, and which frequently produces difficulty of breathing, and the pains of chronic rheumatism, and lastly the earthy part of the living bones are dissolved and absorbed by the increased actions of this system of vessels. See Sect. XXXIII. 3. 1. The earthy part of bones in this disease of the innutrition of them seems to suffer a solution, and reabsorption; while the secerning vessels do not supply a sufficient quantity of calcareous earth and phosphoric acid, which constitute the substance of bones. As calcareous earth abounds every where, is the want of phosphoric acid the remote cause? One cause of this malady is given in the Philosophic Transactions, where the patient had been accustomed to drink large quantities of vinegar. Two cases are described by Mr. Gouch. In one case, which I saw, a considerable quantity of calcareous earth, and afterwards of bone-ashes, and of decoction of madder, and also of sublimate of mercury, were given without effect. All the bones became soft, many of them broke, and the patient seemed to die from the want of being able to distend her chest owing to the softness of the ribs. M. M. Salt of urine, called sal microcosmicum, phosphorated soda. Calcined hartshorn. Bone-ashes. Hard or petrifying water, as that of Matlock, or such as is found in all limestone or marly countries. The calcareous earth in these waters might possibly be carried to the bones, as madder is known to colour them. Warm bath. Volatile or fixed alcali as a lotion on the spine, or essential oils. The innutrition of the bones is often first to be perceived by the difficulty of breathing and palpitation of the heart on walking a little faster than usual, which I suppose is owing to the softness of the ends of the ribs adjoining to the sternum; on which account they do not perfectly distend the chest, when they are raised by the pectoral and intercostal muscles with greater force than usual. After this the spine becomes curved both by the softness of its vertebræ, and for the purpose of making room for the disturbed heart. See Species 16 of this genus. As these patients are pale and weak, there would seem to be a deficiency of oxygene in their blood, and in consequence a deficiency of phosphoric acid; which is probably produced by oxygene in the act of respiration. Mr. Bonhome in the Chemical Annals, August, 1793, supposes the rickets to arise from the prevalence of vegetable or acetous acid, which is known to soften bones out of the body. Mr. Dettaen seems to have espoused a similar opinion, and both of them in consequence give alcalies and testacea. If this theory was just, the soft bones of such patients should shew evident marks of such acidity after death; which I believe has not been observed. Nor is it analogous to other animal facts, that nutritious fluids secreted by the finest vessels of the body should be so little animalized, as to retain acetous or vegetable acidity. The success attending the following case in so short a time as a fortnight I ascribed principally to the use of the warm bath; in which the patient continued for full half an hour every night, in the degree of heat, which was most grateful to her sensation, which might be I suppose about 94. Miss ----, about ten years of age, and very tall and thin, has laboured under palpitation of her heart, and difficult breathing on the least exercise, with occasional violent dry cough, for a year or more, with dry lips, little appetite either for food or drink, and dry skin, with cold extremities. She has at times been occasionally worse, and been relieved in some degree by the bark. She began to bend forwards, and to lift up her shoulders. The former seemed owing to a beginning curvature of the spine, the latter was probably caused to facilitate her difficult respiration. M. M. She used the warm bath, as above related; which by its warmth might increase the irritability of the smallest series of vessels, and by supplying more moisture to the blood might probably tend to carry further the materials, which form calcareous or bony particles, or to convey them in more dilute solution. She took twice a day twenty grains of extract of bark, twenty grains of soda phosphorata, and ten grams of chalk, and ten of calcined hartshorn mixed into a powder with ten drops of laudanum; with flesh food both to dinner and supper; and port wine and water instead of the small beer, she had been accustomed to; she lay on a sofa frequently in a day, and occasionally used a neck-swing. 15. _Rachitis._ Rickets. The head is large, protuberant chiefly on the forepart. The smaller joints are swelled; the ribs depressed; the belly tumid, with other parts emaciated. This disease from the innutrition or softness of the bones arose about two centuries ago; seems to have been half a century in an increasing or spreading state; continued about half a century at its height, or greatest diffusion; and is now nearly vanished: which gives reason to hope, that the small-pox, measles, and venereal disease, which are all of modern production, and have already become milder, may in process of time vanish from the earth, and perhaps be succeeded by new ones! See the preceding species. 16. _Spinæ distortio._ Distortion of the spine is another disease originating from the innutrition or softness of the bones. I once saw a child about six years old with palpitation of heart, and quickness of respiration, which began to have a curvature of the spine; I then doubted, whether the palpitation and quick respiration were the cause or consequence of the curvature of the spine; suspecting either that nature had bent the spine outwards to give room to the enlarged heart; or that the malformation of the chest had compressed and impeded the movements of the heart. But a few weeks ago on attending a young lady about ten years old, whose spine had lately began to be distorted, with very great difficulty and quickness of respiration, and alarming palpitation of the heart, I convinced myself, that the palpitation and difficult respiration were the effect of the change of the cavity of the chest from the distortion of the spine; and that the whole was therefore a disease of the innutrition or softness of the bones. For on directing her to lie down much in the day, and to take the bark, the distortion became less, and the palpitation and quick respiration became less at the same time. After this observation a neck-swing was directed, and she took the bark, madder, and bone-ashes; and she continues to amend both in her shape and health. Delicate young ladies are very liable to become awry at many boarding schools. This is occasioned principally by their being obliged too long to preserve an erect attitude, by sitting on forms many hours together. To prevent this the school-seats should have either backs, on which they may occasionally rest themselves; or desks before them, on which they may occasionally lean. This is a thing of greater consequence than may appear to those, who have not attended to it. When the least tendency to become awry is observed, they should be advised to lie down on a bed or sofa for an hour in the middle of the day for many months; which generally prevents the increase of this deformity by taking off for a time the pressure on the spine of the back, and it at the same time tends to make them grow taller. Young persons, when nicely measured, are found to be half an inch higher in a morning than at night; as is well known to those, who inlist very young men for soldiers. This is owing to the cartilages between the bones of the back becoming compressed by the weight of the head and shoulders on them during the day. It is the same pressure which produces curvatures and distortions of the spine in growing children, where the bones are softer than usual; and which may thus be relieved by an horizontal posture for an hour in the middle of the day, or by being frequently allowed to lean on a chair, or to play on the ground on a carpet. Young ladies should also be directed, where two sleep in a bed, to change every night, or every week, their sides of the bed; which will prevent their tendency to sleep always on the same side; which is not only liable to produce crookedness, but also to occasion diseases by the internal parts being so long kept in uniform contact as to grow together. For the same reason they should not be allowed to sit always on the same side of the fire or window, because they will then be inclined too frequently to bend themselves to one side. Another great cause of injury to the shape of young ladies is from the pressure of stays, or other tight bandages, which at the same time cause other diseases by changing the form or situation of the internal parts. If a hard part of the stays, even a knot of the thread, with which they are sewed together, is pressed hard upon one side more than the other, the child bends from the side most painful, and thus occasions a curvature of the spine. To counteract this effect such stays, as have fewest hard parts, and especially such as can be daily or weekly turned, are preferable to others. [Illustration] Where frequent lying down on a sofa in the day-time, and swinging frequently for a short time by the hands or head, with loose dress, do not relieve a beginning distortion of the back; recourse may be had to a chair with stuffed moveable arms for the purpose of suspending the weight of the body by cushions under the arm-pits, like resting on crutches, or like the leading strings of infants. From the top of the back of the same chair a curved steel bar may also project to suspend the body occasionally, or in part by the head, like the swing above mentioned. The use of this chair is more efficacious in straightening the spine, than simply lying down horizontally; as it not only takes off the pressure of the head and shoulders from the spine, but at the same time the inferior parts of the body contribute to draw the spine straight by their weight; or lastly, recourse may be had to a spinal machine first described in the Memoires of the academy of surgery in Paris, Vol. III. p. 600, by M. Le Vacher, and since made by Mr. Jones, at N^o 6, North-street, Tottenham-court Road, London, which suspends the head, and places the weight of it on the hips. This machine is capable of improvement by joints in the bar at the back of it, to permit the body to bend forwards without diminishing the extension of the spine. The objections of this machine of M. Vacher, which is made by Mr. Jones, are first, that it is worn in the day-time, and has a very unsightly appearance. Mr. Jones has endeavoured to remedy this, by taking away the curved bar over the head, and substituting in its place a forked bar, rising up behind each ear, with webs fastened to it, which pass under the chin and occiput. But this is not an improvement, but a deterioration of M. Vacher's machine, as it prevents the head from turning with facility to either side. Another objection is, that its being worn, when the muscles of the back are in action, it is rather calculated to prevent the curvature of the spine from becoming greater, than to extend the spine, and diminish its curvature. [Illustration] For this latter purpose I have made a steel bow, as described in the annexed plate, which receives the head longitudinally from the forehead to the occiput; having a fork furnished with a web to sustain the chin, and another to sustain the occiput. The summit of the bow is fixed by a swivel to the board going behind the head of the bed above the pillow. The bed is to be inclined from the head to the feet about twelve or sixteen inches. Hence the patient would be constantly sliding down during sleep, unless supported by this bow, with webbed forks, covered also with fur, placed beneath the chin, and beneath the occiput. There are also proper webs lined with fur for the hands to take hold off occasionally, and also to go under the arms. By these means I should hope great advantage from gradually extending the spine during the inactivity of the muscles of the back; and that it may be done without disturbing the sleep of the patient, and if this should happen, the bow is made to open by a joint at the summit of it, so as to be instantly disengaged from the neck by the hand of the wearer. This bow I have not yet had opportunity to make use of, but it may be had from Mr. Harrison, whitesmith, Bridge-gate, Derby. It will be from hence easily perceived, that all other methods of confining or directing the growth of young people should be used with great skill; such as back-boards, or bandages, or stocks for the feet; and that their application should not be continued too long at a time, lest worse consequences should ensue, than the deformity they were designed to remove. To this may be added, that the stiff erect attitude taught by some modern dancing masters does not contribute to the grace of person, but rather militates against it; as is well seen in one of the prints in Hogarth's Analysis of Beauty; and is exemplifyed by the easy grace of some of the ancient statues, as of the Venus de Medici, and the Antinous, and in the works of some modern artists, as in a beautiful print of Hebe feeding an Eagle, painted by Hamilton, and engraved by Eginton, and many of the figures of Angelica Kauffman. Where the bone of one of the vertebræ of the back has been swelled on both sides of it, so as to become protuberant, issues near the swelled part have been found of great service, as mentioned in Species 18 of this genus. This has induced me to propose in curvatures of the spine, to put an issue on the outside of the curve, where it could be certainly ascertained, as the bones on the convex side of the curve must be enlarged; in one case I thought this of service, and recommend the further trial of it. In the tendency to curvature of the spine, whatever strengthens the general constitution is of service; as the use of the cold bath in the summer months. This however requires some restriction both in respect to the degree of coldness of the bath, the time of continuing in it, and the season of the year. Common springs, which are of forty-eight degrees of heat, are too cold for tender constitutions, whether of children or adults, and frequently do them great and irreparable injury. The coldness of river water in the summer months, which is about sixty-eight degrees, or that of Matlock, which is about sixty-eight, or of Buxton, which is eighty-two, are much to be preferred. The time of continuing in the bath should be but a minute or two, or not so long as to occasion a trembling of the limbs from cold. In respect to the season of the year, delicate children should certainly only bathe in the summer months; as the going frequently into the cold air in winter will answer all the purposes of the cold bath. 17. _Claudicatio coxaria._ Lameness of the hip. A nodding of the thigh-bone is said to be produced in feeble children by the softness of the neck or upper part of that bone beneath the cartilage; which is naturally bent, and in this disease bends more downwards, or nods, by the pressure of the body; and thus renders one leg apparently shorter than the other. In other cases the end of the bone is protruded out of its socket, by inflammation or enlargement of the cartilages or ligaments of the joint, so that it rests on some part of the edge of the acetabulum, which in time becomes filled up. When the legs are straight, as in standing erect, there is no verticillary motion in the knee-joint; all the motion then in turning out the toes further than nature designed, must be obtained by straining in some degree this head of the thigh-bone, or the acetabulum, or cavity, in which it moves. This has induced me to believe, that this misfortune of the nodding of the head by the bone, or partial dislocation of it, by which one leg becomes shorter than the other, is sometimes occasioned by making very young children stand in what are called stocks; that is with their heels together, and their toes quite out. Whence the socket of the thigh-bone becomes inflamed and painful, or the neck of the bone is bent downward and outwards. In this case there is no expectation of recovering the straightness of the end of the bone; but these patients are liable to another misfortune, that is, to acquire afterwards a distortion of the spine; for as one leg is shorter than the other, they sink on that side, and in consequence bend the upper part of their bodies, as their shoulders, the contrary way, to balance themselves; and then again the neck is bent back again towards the lame side, to preserve the head perpendicular; and thus the figure becomes quite distorted like the letter S, owing originally to the deficiency of the length of one limb. The only way to prevent this curvature of the spine is for the child to wear a high-heeled shoe or patten on the lame foot, so as to support that side on the same level with the other, and thus to prevent a greater deformity. I have this day seen a young lady about twelve, who does not limp or waddle in walking; but nevertheless, when she stands or sits, she sinks down towards her right side, and turns out that toe more than the other. Hence, both as she sits and stands, she bends her body to the right; whence her head would hang a little over her right shoulder; but to replace this perpendicularly, she lifts up her left shoulder and contracts the muscles on that side of the neck; which are therefore become thicker and stronger by their continued action; but there is not yet any very perceptible distortion of the spine. As her right toe is turned outward rather more than natural, this shews the disease to be in the hip-joint; because, when the limb is stretched out, the toe cannot turn horizontally in the least without moving the end of the thigh-bone; although when the knee is bent, the toe can be turned through one third or half of a circle by the rotation of the tibia and fibula of the leg round each other. Hence if children are set in stocks with their heels touching each other as they sit, and are then made to rise up, till they stand erect, the socket or head of the thigh-bone becomes injured, especially in those children, whose bones are soft; and a shortness of that limb succeeds either by the bending of the neck of the thigh-bone, or by its getting out of the acetabulum; and a consequent rising of one shoulder, and a curvature of the spine is produced from so distant a cause. M. M. An elastic cushion made of curled hair should be placed under the affected hip, whenever she sits; or should be fitted to the part by means of drawers, so that she cannot avoid sitting on it. A neck-swing, and lying down in the day, should be occasionally used to prevent or remove any curvature of the spine. The rest as in Species 13 and 15 of this genus. 18. _Spina protuberans._ Protuberant spine. One of the bones of the spine swells, and rises above the rest. This is not an uncommon disease, and belongs to the innutrition of the bones, as the bone must become soft before it swells; which softness is owing to defect of the secretion of phosphorated calcareous earth. The swelling of the bone compresses a part of the brain, called the spinal marrow, within the cavity of the back-bones; and in consequence the lower limbs become paralytic, attended sometimes with difficulty of emptying the bladder and rectum. M. M. Issues put on each side of the prominent bone are of great effect, I suppose, by their stimulus; which excites into action more of the sensorial powers of irritation and sensation, and thus gives greater activity to the vascular system in their vicinity. The methods recommended in distortion of the spine are also to be attended to. 19. _Spina bifida._ Divided spine, called also Hydrorachitis, as well as the Hydrocephalus externus, are probably owing in part to a defect of ossification of the spine and cranium; and that the collection of fluid beneath them may originate from the general debility of the system; which affects both the secerning, and absorbent vessels. A curious circumstance, which is affirmed to attend the spina bifida, is, that on compressing the tumor with the hand gently, the whole brain becomes affected, and the patient falls asleep. I suppose the same must happen on compressing the hydrocephalus externus? See Sect. XVIII. 20. 20. _Ossis palati defectus._ A defect of the bone of the palate, which frequently accompanies a division of the upper lip, occurs before nativity; and is owing to the deficient action of the secerning system, from whence the extremities are not completed. From a similar cause I have seen the point of the tongue deficient, and one joint of the two least fingers, and of the two least toes, in the same infant; who was otherwise a fine girl. See Sect. XXXIX. 4. 4. The operation for the hare-lip is described by many surgical writers; but there is a person in London, who makes very ingenious artificial palates; which prevents that defect of speech, which attends this malformation. This factitious palate consists of a thin plate of silver of the shape and form of the roof of the mouth; from the front edge to the back edge of this silver plate four or five holes are made in a straight line large enough for a needle to pass through them; on the back of it is then sewed a piece of sponge; which when expanded with moisture is nearly as large as the silver plate. This sponge is slipped through the division of the bone of the palate, so as to lie above it, while the silver plate covers the aperture beneath, and is suspended by the expanding sponge. This is removed every night and washed, and returned into its place in the morning; on this account it is convenient to have five or six of them, for the sake of cleanliness. I have been more particular in describing this invention, as I do not know the name, or place of residence, of the maker. * * * * * ORDO II. _Decreased Irritation._ GENUS III. _The Decreased Action of the Absorbent System._ Some decrease of heat attends these diseases, though in a less degree than those of the last genus, because the absorbent system of glands do not generate so much heat in their healthy state of action as the secerning system of glands, as explained in Class I. 1. 3. SPECIES. 1. _Mucus faucium frigidus._ Cold mucus from the throat. Much mucus, of rather a saline taste, and less inspissated than usual, is evacuated from the fauces by hawking, owing to the deficient absorption of the thinner parts of it. This becomes a habit in some elderly people, who are continually spitting it out of their mouths; and has probably been brought on by taking snuff, or smoking tobacco; which by frequently stimulating the fauces have at length rendered the absorbent vessels less excitable by the natural stimulus of the saline part of the secretion, which ought to be reabsorbed, as soon as secreted. M. M. A few grains of powder of bark frequently put into the mouth, and gradually diffused over the fauces. A gargle of barley water. 2. _Sudor frigidus._ The cold dampness of the hands of some people is caused by the deficient absorption of perspirable matter; the clammy or viscid feel of it is owing to the mucous part being left upon the skin. The coldness is produced both by the decreased action of the absorbent system, and by the evaporation of a greater quantity of the perspirable matter into the air, which ought to have been absorbed. M. M. Wash the hands in lime water, or with a small quantity of volatile alcali in water. 3. _Catarrhus frigidus._ The thin discharge from the nostrils in cold weather. The absorbent vessels become torpid by the diminution of external heat, sooner than the secerning ones, which are longer kept warm by the circulating blood, from which they select the fluid they secrete; whereas the absorbent vessels of the nostrils drink up their fluids, namely the thin and saline part of the mucus, after it has been cooled by the atmosphere. Hence the absorbents ceasing to act, and the secerning vessels continuing some time longer to pour out the mucus, a copious thin discharge is produced, which trickles down the nostrils in cold weather. This discharge is so acrid as to inflame the upper lip; which is owing to the neutral salts, with which it abounds, not being reabsorbed; so the tears in the fistula lacrymalis inflame the cheek. See Class I. 1. 2. 7. 4. _Expectoratio frigida._ Cold expectoration. Where the pulmonary absorption is deficient, an habitual cough is produced, and a frequent expectoration of thin saline mucus; as is often seen in old enfeebled people. Though the stimulus of the saline fluid, which attends all secretions, is not sufficient to excite the languid absorbent vessels to imbibe it; yet this saline part, together with the increased quantity of the whole of the secreted mucus, stimulates the branches of the bronchia, so as to induce an almost incessant cough to discharge it from the lungs. A single grain of opium, or any other stimulant drug, as a wine-posset with spirit of hartshorn, will cure this cold cough, and the cold catarrh of the preceding article, like a charm, by stimulating the torpid mouths of the absorbents into action. Which has given rise to an indiscriminate and frequently pernicious use of the warm regimen in coughs and catarrhs of the warm or inflammatory kind, to the great injury of many. M. M. Half a grain of opium night and morning promotes the absorption of the more fluid and saline parts, and in consequence thickens the mucus, and abates its acrimony. Warm diluent drink, wine-whey, with volatile alcali. 5. _Urina uberior pallida._ On being exposed naked to cold air, or sprinkled with cold water, a quantity of pale urine is soon discharged; for the absorbents of the bladder become torpid by their sympathy with those of the skin; which are rendered quiescent by the diminution of external heat; but the kidnies continue to secrete the urine, and as no part of it is absorbed, it becomes copious and pale. This happens from a similar cause in cold fits of agues; and in less degree to many debilitated constitutions, whose extremities are generally cold and pale. The great quantity of limpid water in hysteric cases, and in diabætes, belongs to Class I. 3. 1. 10. I. 3. 2. 6. M. M. Tincture of cantharides, opium, alum, sorbentia. Flannel shirt in cold weather. Animal food. Beer. Wine. Friction. Exercise. Fire. 6. _Diarrhoea frigida._ Liquid stools are produced by exposing the body naked to cold air, or sprinkling it with cold water, for the same reason as the last article. But this disease is sometimes of a dangerous nature; the intestinal absorption being so impaired, that the aliment is said to come away undiminished in quantity, and almost unchanged by the powers of digestion, and is then called lientery. The mucus of the rectum sometimes comes away like pellucid hartshorn jelly, and liquefies by heat like that, towards the end of inirritative fevers, which is owing to the thinner part of the mucus not being absorbed, and thus resembles the catarrh of some old people. M. M. Opium, campechy wood, armenian bole. Blister. Flannel shirt in cold weather. Clysters with opium. Friction on the bowels morning and night. Equitation twice a day. 7. _Fluor albus frigidus._ Cold fluor albus. In weak constitutions, where this discharge is pellucid and thin, it must proceed from want of absorption of the mucous membrane of the vagina, or uterus, and not from an increased secretion. This I suspect to be the most frequent kind of fluor albus; the former one described at Class I. 1. 2. 11. attends menstruation, or is a discharge instead of it, and thus resembles the venereal orgasm of female quadrupeds. The discharge in this latter kind being more saline, is liable to excoriate the part, and thus produce smarting in making water; in its great degree it is difficult to cure. M. M. Increase the evacuation by stool and by perspiration, by taking rhubarb every night, about six or ten grains with one grain of opium for some months. Flannel shirt in winter. Balsam copaiva. Gum kino, bitters, chalybeates, friction over the whole skin with flannel morning and night. Partial cold bath, by sprinkling the loins and thighs, or sponging them with cold water. Mucilage, as isinglass boiled in milk; blanc mange, hartshorn jelly, are recommended by some. Tincture of cantharides sometimes seems of service given from ten to twenty drops or more, three or four times a day. A large plaster of burgundy pitch and armenian bole, so as to cover the loins and lower part of the belly, is said to have sometimes succeeded by increasing absorption by its compression in the manner of a bandage. A solution of metallic salts, as white vitriol, sixty grains to a pint; or an infusion of oak-bark may be injected into the vagina. Cold bath. 8. _Gonorrhoea frigida._ Cold gleet. Where the gleet is thin and pellucid, it must arise from the want of absorption of the membranes of the urethra, rather than from an increased secretion from them. This I suppose to be a more common disease than that mentioned at Class I. 1. 2. 10. M. M. Metallic injections, partial cold bath, internal method as in the fluor albus above described. Balsam of copaiva. Tincture of cantharides. 9. _Hepatis tumor._ The liver becomes enlarged from defect of the absorption of mucus from its cells, as in anasarca, especially in feeble children; at the same time less bile is secreted from the torpid circulation in the vena portæ. And as the absorbents, which resume the thinner parts of the bile from the gall-bladder and hepatic ducts, are also torpid or quiescent, the bile is more dilute, as well as in less quantity. From the obstruction of the passage of the blood through the compressed vena porta these patients have tumid bellies, and pale bloated countenances; their paleness is probably owing to the deficiency of the quantity of red globules in the blood in consequence of the inert state of the bile. These symptoms in children are generally attended with worms, the dilute bile and the weak digestion not destroying them. In sleep I have seen fleuke-worms in the gall-ducts themselves among the dilute bile; which gall-ducts they eat through, and then produce ulcers, and the hectic fever, called the rot. See Class I. 1. 4. 10. and Article IV. 2. 6. M. M. After a calomel purge, crude iron-filings are specific in this disease in children, and the worms are destroyed by the returning acrimony and quantity of the bile. A blister on the region of the liver. Sorbentia, as worm-seed, santonicum. Columbo. Bark. 10. _Chlorosis._ When the defect of the due action of both the absorbent and secerning vessels of the liver affects women, and is attended with obstruction of the catamenia, it is called chlorosis; and is cured by the exhibition of steel, which restores by its specific stimulus the absorbent power of the liver; and the menstruation, which was obstructed in consequence of debility, recurs. Indigestion, owing to torpor of the stomach, and a consequent too great acidity of its contents, attend this disease; whence a desire of eating chalk, or marl. Sometimes a great quantity of pale urine is discharged in a morning, which is owing to the inaction of the absorbents, which are distributed on the neck of the bladder, during sleep. The swelling of the ankles, which frequently attends chlorosis, is another effect of deficient action of the absorbent system; and the pale countenance is occasioned by the deficient quantity of red globules of blood, caused by the deficient quantity or acrimony of the bile, and consequent weakness of the circulation. The pulse is so quick in some cases of chlorosis, that, when attended with an accidental cough, it may be mistaken for pulmonary consumption. This quick pulse is owing to the debility of the heart from the want of stimulus occasioned by the deficiency of the quantity, and acrimony of the blood. M. M. Steel. Bitters. Constant moderate exercise. Friction with flannel all over the body and limbs night and morning. Rhubarb five grains, opium half a grain, every night. Flesh diet, with small beer, or wine and water. The disease continues some months, but at length subsides by the treatment above described. A bath of about eighty degrees, as Buxton Bath, is of service; a colder bath may do great injury. 11. _Hydrocele._ Dropsy of the vagina testis. Dropsies have been divided into the incysted and the diffused, meaning those of the cellular membrane, the cells of which communicate with each other like a sponge, and those of any other cavity of the body. The collections of mucous fluids in the various cells and cavities of the body arise from the torpor of the absorbent vessels of those parts. It is probable, that in dropsies attended with great thirst the cutaneous absorbents become paralytic first; and then from the great thirst, which is thus occasioned by the want of atmospheric moisture, the absorption of the fat ensues; as in fevers attended with great thirst, the fat is quickly taken up. See Obesitas I. 2. 3. 17. Some have believed, that the cellular and adipose membranes are different ones; as no fat is ever deposited in the eye-lids or scrotum, both which places are very liable to be distended with the mucilaginous fluid of the anasarca, and with air in Emphysema. Sometimes a gradual absorption of the accumulated fluid takes place, and the thinner parts being taken up, there remains a more viscid fluid, or almost a solid in the part, as in some swelled legs, which can not easily be indented by the pressure of the finger, and are called scorbutic. Sometimes the paralysis of the absorbents is completely removed, and the whole is again taken up into the circulation. The Hydrocele is known by a tumor of the scrotum, which is without pain, gradually produced, with fluctuation, and a degree of pellucidity, when a candle is held behind it; it is the most simple incysted dropsy, as it is not in general complicated with other diseases, as ascites with schirrous liver, and hydrocephalus internus, with general debility. The cure of this disease is effected by different ways; it consists in discharging the water by an external aperture; and by so far inflaming the cyst and testicle, that they afterwards grow together, and thus prevent in future any secretion or effusion of mucus; the disease is thus cured, not by the revivescence of the absorbent power of the lymphatics, but by the prevention of secretion by the adhesion of the vagina to the testis. This I believe is performed with less pain, and is more certainly manageable by tapping, or discharging the fluid by means of a trocar, and after the evacuation of it to fill the cyst with a mixture of wine and water for a few minutes till the necessary degree of stimulus is produced, and then to withdraw it; as recommended by Mr. Earle. See also Medical Commentaries by Dr. Duncan, for 1793. 12. _Hydrocephalus internus_, or dropsy of the ventricles of the brain, is fatal to many children, and some adults. When this disease is less in quantity, it probably produces a fever, termed a nervous fever, and which is sometimes called a worm fever, according to the opinion of Dr. Gilchrist, in the Scots Medical essays. This fever is attended with great inirritability, as appears from the dilated pupils of the eyes, in which it corresponds with the dropsy of the brain. And the latter disease has its paroxysms of quick pulse, and in that respect corresponds with other fevers with inirritability. The hydrocephalus internus is distinguished from apoplexy by its being attended with fever, and from nervous fever by the paroxysms being very irregular, with perfect intermissions many times in a day. In nervous fever the pain of the head generally affects the middle of the forehead; in hydrocephalus internus it is generally on one side of the head. One of the earliest criterions is the patient being uneasy on raising his head from the pillow, and wishing to lie down again immediately; which I suppose is owing to the pressure of the water on the larger trunks of the blood-vessels entering the cavity being more intolerable than on the smaller ones; for if the larger trunks are compressed, it must inconvenience the branches also; but if some of the small branches are compressed only, the trunks are not so immediately incommoded. Blisters on the head, and mercurial ointment externally, with calomel internally, are principally recommended in this fatal disease. When the patient cannot bear to be raised up in bed without great uneasiness, it is a bad symptom. So I believe is deafness, which is commonly mistaken for stupor. See Class I. 2. 5. 6. And when the dilatation of the pupil of either eye, or the squinting is very apparent, or the pupils of both eyes much dilated, it is generally fatal. As by stimulating one branch of lymphatics into inverted motion, another branch is liable to absorb its fluid more hastily; suppose strong errhines, as common tobacco snuff to children, or one grain of turpeth mineral, (Hydrargyrus vitriolatus), mixed with ten or fifteen grains of sugar, was gradually blown up the nostrils? See Class I. 3. 2. 1. I have tried common snuff upon two children in this disease; one could not be made to sneeze, and the other was too near death to receive advantage. When the mercurial preparations have produced salivation, I believe they may have been of service, but I doubt their good effect otherwise. In one child I tried the tincture of Digitalis; but it was given with too timid a hand, and too late in the disease, to determine its effects. See Sect. XXIX. 5. 9. As all the above remedies generally fail of success, I think frequent, almost hourly, shocks of electricity from very small charges might be passed through the head in all directions with probability of good event. And the use of the trephine, where the affected side can be distinguished. See Strabismus, Class I. 2. 5. 4. When one eye is affected, does the disease exist in the ventricule of that side? 13. _Ascites._ The dropsy of the cavity of the abdomen is known by a tense swelling of the belly; which does not sound on being struck like the tympany; and in which a fluctuation can be readily perceived by applying one hand expanded on one side, and striking the tumour on the other. Effusions of water into large cavities, as into that of the abdomen or thorax, or into the ventricules of the brain or pericardium, are more difficult to be reabsorbed, than the effusion of fluids into the cellular membrane; because one part of this extensive sponge-like system of cells, which connects all the solid parts of the body, may have its power of absorption impaired, at the same time that some other part of it may still retain that power, or perhaps possess it in an increased degree; and as all these cells communicate with each other, the fluid, which abounds in one part of it, can be transferred to another, and thus be reabsorbed into the circulation. In the ascites, cream of tartar has sometimes been attended with success; a dram or two drams are given every hour in a morning till it operates, and is to be repeated for several days; but the operation of tapping is generally applied to at last. Dr. Sims, in the Memoirs of the Medical Society of London, Vol. III. has lately proposed, what he believes to be a more successful method of performing this operation, by making a puncture with a lancet in the scar of the navel, and leaving it to discharge itself gradually for several days, without introducing a canula, which he thinks injurious both on account of the too sudden emission of the fluid, and the danger of wounding or stimulating the viscera. This operation I have twice known performed with less inconvenience, and I believe with more benefit to the patient, than the common method. After the patient has been tapped, some have tried injections into the cavity of the abdomen, but hitherto I believe with ill event. Nor are experiments of this kind very promising of success. First because the patients are generally much debilitated, most frequently by spirituous potation, and have generally a disease of the liver, or of other viscera. And secondly, because the quantity of inflammation, necessary to prevent future secretion of mucus into the cavity of the abdomen, by uniting the peritoneum with the intestines or mesentery, as happens in the cure of the hydrocele, would I suppose generally destroy the patient, either immediately, or by the consequence of such adhesions. This however is not the case in respect to the dropsy of the ovarium, or in the hydrocele. 14. _Hydrops thoracis._ The dropsy of the chest commences with loss of flesh, cold extremities, pale countenance, high coloured urine in small quantity, and general debility, like many other dropsies. The patient next complains of numbness in the arms, especially when elevated, with pain and difficulty of swallowing, and an absolute impossibility of lying down for a few minutes, or with sudden starting from sleep, with great difficulty of breathing and palpitation of his heart. The numbness of the arms is probably owing more frequently to the increased action of the pectoral muscles in respiration, whence they are less at liberty to perform other offices, than to the connexion of nerves mentioned in Sect. XXIX. 5. 2. The difficulty of swallowing is owing to the compression of the oesophagus by the lymph in the chest; and the impossibility of breathing in an horizontal posture originates from this, that if any parts of the lungs must be rendered useless, the inability of the extremities of them must be less inconvenient to respiration; since if the upper parts or larger trunks of the air-vessels should be rendered useless by the compression of the accumulated lymph, the air could not gain admittance to the other parts, and the animal must immediately perish. If the pericardium is the principal seat of the disease, the pulse is quick and irregular. If only the cavity of the thorax is hydropic, the pulse is not quick nor irregular. If one side is more affected than the other, the patient leans most that way, and has more numbness in that arm. The hydrops thoracis is distinguished from the anasarca pulmonum, as the patient in the former cannot lie down half a minute; in the latter the difficulty of breathing, which occasions him to rise up, comes on more gradually; as the transition of the lymph in the cellular membranes from one part to another of it is slower, than that of the effused lymph in the cavity of the chest. The hydrops thoracis is often complicated with fits of convulsive breathing; and then it produces a disease for the time very similar to the common periodic asthma, which is perhaps owing to a temporary anasarca of the lungs; or to an impaired venous absorption in them. These exacerbations of difficult breathing are attended with cold extremities, cold breath, cold tongue, upright posture with the mouth open, and a desire of cold air, and a quick, weak, intermittent pulse, and contracted hands. These exacerbations recur sometimes every two or three hours, and are relieved by opium, a grain every hour for two or three doses, with ether about a dram in cold water; and seem to be a convulsion of the muscles of respiration induced by the pain of the dyspnea. As in Class III. 1. 1. 9. M. M. A grain of dried squill, and a quarter of a grain of blue vitriol every hour for six or eight hours, unless it vomit or purge. A grain of opium. Blisters. Calomel three grains every third day, with infusion of senna. Bark. Chalybeates. Puncture in the side. Can the fluctuation in the chest be heard by applying the ear to the side, as Hippocrates asserts? Can it be felt by the hand or by the patient before the disease is too great to admit of cure by the paracentesis? Does this dropsy of the chest often come on after peripneumony? Is it ever cured by making the patient sick by tincture of digitalis? Could it be cured, if on one side only, by the operation of puncture between the ribs, and afterwards by inflaming the cavity by the admission of air for a time, like the cure of the hydrocele; the pleura afterwards adhering wholly to that lobe of the lungs, so as to prevent any future effusion of mucus? 15. _Hydrops ovarii._ Dropsy of the ovary is another incysted dropsy, which seldom admits of cure. It is distinguished from ascites by the tumour and pain, especially at the beginning, occupying one side, and the fluctuation being less distinctly perceptible. When it happens to young subjects it is less liable to be mistaken for ascites. It affects women of all ages, either married or virgins; and is produced by cold, fear, hunger, bad food, and other debilitating causes. I saw an elegant young lady, who was shortly to have been married to a sensible man, with great prospect of happiness; who, on being overturned in a chaise in the night, and obliged to walk two or three miles in wet, cold, and darkness, became much indisposed, and gradually afflicted with a swelling and pain on one side of the abdomen; which terminated in a dropsy of the ovary, and destroyed her in two or three years. Another young woman I recollect seeing, who was about seventeen, and being of the very inferior class of people, seemed to have been much weakened by the hardship of a cold floor, and little or no bed, with bad food; and who to these evils had to bear the unceasing obloquy of her neighbours, and the persecution of parish officers. The following is abstracted from a letter of my friend Mr. Power, surgeon, at Bosworth in Leicestershire, on examining the body of an elderly lady who died of this disease, March 29, 1793. "On opening the abdomen I found a large cyst attached to the left ovarium by an elastic neck as thick as the little finger, and so callous as not to admit of being separated by scissars without considerable difficulty. The substance of the cyst had an appearance much resembling the gravid uterus near the full period of gestation, and was as thick. It had no attachment to the peritonæum, or any of the viscera, except by the hard callous neck I have mentioned; so that the blood must with difficulty have been circulated through it for some time. Its texture was extremely tender, being easily perforated with the finger, was of a livid red colour, and evidently in a sphacelated state. It contained about two gallons of a fluid of the colour of port wine, without any greater tenacity. It has fallen to my lot to have opened two other patients, whose deaths were occasioned by incysted dropsy of the ovarium. In one of these the ovarium was much enlarged with eight or ten cysts on its surface, but there was no adhesion formed by any of the cysts to any other part; nor had the ovarium formed any adhesion with the peritonæum, though in a very diseased state. In the other the disease was more simple, being only one cyst, without any attachment but to the ovarium. "As the ovarium is a part not necessary to life, and dropsies of this kind are so generally fatal in the end, I think I shall be induced, notwithstanding the hazard attending wounds, which penetrate the cavity of the abdomen, to propose the extirpation of the diseased part in the first case, which occurs to me, in which I can with precision say, that the ovarium is the seat of the disease, and the patient in other respects tolerably healthy; as the cavity of the abdomen is often opened in other cases without bad consequences." An argument, which might further countenance the operation thus proposed by Mr. Power, might be taken from the disease frequently affecting young persons; from its being generally in these subjects local and primary; and not like the ascites, produced or accompanied with other diseased viscera; and lastly, as it is performed in adult quadrupeds, as old sows, with safety, though by awkward operators. 16. _Anasarca pulmonum._ The dropsy of the cellular membrane of the lungs is usually connected with that of the other parts of the system. As the cells of the whole cellular membrane communicate with each other, the mucaginous fluid, which remains in any part of it for want of due absorption, sinks down to the most depending cells; hence the legs swell, though the cause of the disease, the deficiency of absorption, may be in other parts of the system. The lungs however are an exception to this, since they are suspended in the cavity of the thorax, and have in consequence a depending part of their own. The anasarca of the lungs is known by the difficulty of respiration accompanied with swelled legs, and with a very irregular pulse. This last circumstance has generally been ascribed to a dropsy at the same time existing in the pericardium, but is more probably owing to the difficult passage of the blood through the lungs; because I found on dissection, in one instance, that the most irregular pulse, which I ever attended to, was owing to very extensive adhesions of the lungs; insomuch that one lobe intirely adhered to the pleura; and secondly, because this kind of dropsy of the lungs is so certainly removed for a time along with the anasarca of the limbs by the use of digitalis. This medicine, as well as emetic tartar, or squill, when given so as to produce sickness, or nausea, or perhaps even without producing either in any perceptible degree, by affecting the lymphatics of the stomach, so as either to invert their motion, or to weaken them, increases by reverse sympathy the action, and consequent absorbent power of these lymphatics, which open into the cellular membrane. But as those medicines seldom succeed in producing an absorption of those fluids, which stagnate in the larger cavities of the body, as in the abdomen, or chest, and do generally succeed in this difficulty of breathing with irregular pulse above described, I conclude that it is not owing to an effusion of lymph into the pericardium, but simply to an anasarca of the lungs. M. M. Digitalis. See Art. V. 2. 1. Tobacco. Squill. Emetic tartar (antimonium tartarizatum). Then Sorbentia. Chalybeates. Opium half a grain twice a day. Raisin wine and water, or other wine and water, is preferred to the spirit and water, which these patients have generally been accustomed to. The usual cause of anasarca is from a diseased liver, and hence it most frequently attends those, who have drank much fermented or spirituous liquors; but I suspect that there is another cause of anasarca, which originates from the brain; and which is more certainly fatal than that, which originates from a diseased liver. These patients, where the anasarca originates from, or commences in, the brain, have not other symptoms of diseased liver; have less difficulty of breathing at the beginning; and hold themselves more upright in their chair, and in walking. In this kind of dropsy I suspect the digitalis has less or no effect; as it particularly increases the absorption from the lungs. 17. _Obesitas._ Corpulency may be called an anasarca or dropsy of fat, since it must be owing to an analogous cause; that is, to the deficient absorption of fat compared to the quantity secreted into the cells which contain it. See Class II. 1. 1. 4. The method of getting free from too much fat without any injury to the constitution, consists, first, in putting on a proper bandage on the belly, so that it can be tightened or relaxed with ease, as a tightish under waistcoat, with a double row of buttons. This is to compress the bowels and increase their absorption, and it thus removes one principal cause of corpulency, which is the looseness of the skin. Secondly, he should omit one entire meal, as supper; by this long abstinence from food the absorbent system will act on the mucus and fat with greater energy. Thirdly, he should drink as little as he can with ease to his sensations; since, if the absorbents of the stomach and bowels supply the blood with much, or perhaps too much, aqueous fluid, the absorbents of the cellular membrane will act with less energy. Fourthly, he should use much salt or salted meat, which will increase the perspiration and make him thirsty; and if he bears this thirst, the absorption of his fat will be greatly increased, as appears in fevers and dropsies with thirst; this I believe to be more efficacious than soap. Fifthly, he may use aerated alcaline water for his drink, which may be supposed to render the fat more fluid,--or he may take soap in large quantities, which will be decomposed in the stomach. Sixthly, short rest, and constant exercise. 18. _Splenis tumor._ Swellings of the spleen, or in its vicinity, are frequently perceived by the hand in intermittents, which are called Ague-cakes, and seem owing to a deficiency of absorption in the affected part. Mr. Y----, a young man about twenty-five years of age, who lived intemperately, was seized with an obstinate intermittent, which had become a continued fever with strong pulse, attended with daily remission. A large hard tumour on the left side, on the region of the spleen, but extending much more downward, was so distinctly perceptible, that one seemed to get one's fingers under the edge of it, much like the feel of the brawn or shield on a boar's shoulder. He was repeatedly bled, and purged with calomel, had an emetic, and a blister on the part, without diminishing the tumour; after some time he took the Peruvian bark, and slight doses of chalybeates, and thus became free from the fever, and went to Bath for several weeks, but the tumour remained. This tumour I examined every four or five years for above thirty years. His countenance was pale, and towards the end of his life he suffered much from ulcers on his legs, and died about sixty, of general debility; like many others, who live intemperately in respect to the ingurgitation of fermented or spirituous liquors. As this tumour commenced in the cold fit of an intermittent fever, and was not attended with pain, and continued so long without endangering his life, there is reason to believe it was simply occasioned by deficient absorption, and not by more energetic action of the vessels which constitute the spleen. See Class II. 1. 2. 13. M. M. Venesection. Emetic, cathartic with calomel; then sorbentia, chalybeates, Peruvian bark. 19. _Genu tumor albus._ White swelling of the knee, is owing to deficient absorption of the lymphatics of the membranes including the joint, or capsular ligaments, and sometimes perhaps of the gland which secretes the synovia; and the ends of the bones are probably affected in consequence. I saw an instance, where a caustic had been applied by an empiric on a large white swelling of the knee, and was told, that a fluid had been discharged from the joint, which became anchylosed, and healed without loss of the limb. M. M. Repeated blisters on the part early in the disease are said to cure it by promoting absorption; saturnine solutions externally are recommended. Bark, animal charcoal, as burnt sponge, opium in small doses. Friction with the hand. 20. _Bronchocele._ Swelled throat. An enlargement of the thyroid glands, said to be frequent in mountainous countries, where river water is drank, which has its source from dissolving snows. This idea is a very ancient one, but perhaps not on that account to be the more depended upon, as authors copy one another. Tumidum guttur quis miratur in alpibus, seems to have been a proverb in the time of Juvenal. The inferior people of Derby are much subject to this disease, but whether more so than other populous towns, I can not determine; certain it is, that they chiefly drink the water of the Derwent, which arises in a mountainous country, and is very frequently blackened as it passes through the morasses near its source; and is generally of a darker colour, and attended with a whiter foam, than the Trent, into which it falls; the greater quantity and whiteness of its froth I suppose may be owing to the viscidity communicated to it by the colouring matter. The lower parts of the town of Derby might be easily supplied with spring water from St. Alkmond's well; or the whole of it from the abundant springs near Bowbridge: the water from which might be conveyed to the town in hollow bricks, or clay-pipes, at no very great expence, and might be received into frequent reservoirs with pumps to them; or laid into the houses. M. M. Twenty grains of burnt sponge with ten of nitre made with mucilage into lozenges, and permitted to dissolve slowly under the tongue twice a day, is asserted to cure in a few months; perhaps other animal charcoal, as candle-snuffs, might do the same. I have directed in the early state of this disease a mixture of common salt and water to be held in the mouth, particularly under the tongue, for a few minutes, four or six times a day for many weeks, which has sometimes succeeded, the salt and water is then spit out again, or in part swallowed. Externally vinegar of squills has been applied, or a mercurial plaster, or fomentations of acetated ammoniac; or ether. Some empirics have applied caustics on the bronchocele, and sometimes, I have been told, with success; which should certainly be used where there is danger of suffocation from the bulk of it. One case I saw, and one I was well informed of, where the bronchocele was cured by burnt sponge, and a hectic fever supervened with colliquative sweats; but I do not know the final event of either of them. De Haen affirms the cure of bronchocele to be effected by flowers of zinc, calcined egg-shells, and scarlet cloth burnt together in a close crucible, which was tried with success, as he assured me, by a late lamented physician, my friend, Dr. Small of Birmingham; who to the cultivation of modern sciences added the integrity of ancient manners; who in clearness of head, and benevolence of heart, had few equals, perhaps no superiors. 21. _Scrophula._ King's evil is known by tumours of the lymphatic glands, particularly of the neck. The upper lip, and division of the nostrils is swelled, with a florid countenance, a smooth skin, and a tumid abdomen. Cullen. The absorbed fluids in their course to the veins in the scrophula are arrested in the lymphatic or conglobate glands; which swell, and after a great length of time, inflame and suppurate. Materials of a peculiar kind, as the variolous and venereal matter, when absorbed in a wound, produce this torpor, and consequent inflammation of those lymphatic glands, where they first arrive, as in the axilla and groin. There is reason to suspect, that the tonsils frequently become inflamed, and suppurate from the matter absorbed from carious teeth; and I saw a young lady, who had both the axillary glands swelled, and which suppurated; which was believed to have been caused by her wearing a pair of new green gloves for one day, when she had perspired much, and was much exhausted and fatigued by walking; the gloves were probably dyed in a solution of verditer. These indolent tumours of the lymphatic glands, which constitute the scrophula, originate from the inirritability of those glands; which therefore sooner fall into torpor after having been stimulated too violently by some poisonous material; as the muscles of enfeebled people sooner become fatigued, and cease to act, when exerted, than those of stronger ones. On the same account these scrophulous glands are much longer in acquiring increase of motion, after having been stimulated into inactivity, and either remain years in a state of indolence, or suppurate with difficulty, and sometimes only partially. The difference between scrophulous tumours, and those before described, consists in this; that in those either glands of different kinds were diseased, or the mouths only of the lymphatic glands were become torpid; whereas in scrophula the conglobate glands themselves become tumid, and generally suppurate after a great length of time, when they acquire new sensibility. See Sect. XXXIX. 4. 5. These indolent tumours may be brought to suppurate sometimes by passing electric shocks through them every day for two or three weeks, as I have witnessed. It is probable, that the alternate application of snow or iced water to them, till they become painfully cold, and then of warm flannel or warm water, frequently repeated, might restore their irritability by accumulation of sensorial power; and thence either facilitate their dispersion, or occasion them to suppurate. See Class II. 1. 4. 13. This disease is very frequent amongst the children of the poor in large towns, who are in general ill fed, ill lodged, and ill clothed; and who are further weakened by eating much salt with their scanty meal of insipid vegetable food, which is seldom of better quality than water gruel, with a little coarse bread in it. See diarrhoea of infants, Class I. 1. 2. 5. Scrophulous ulcers are difficult to heal, which is owing to the deficiency of absorption on their pale and flabby surfaces, and to the general inirritability of the system. See Class I. 1. 3. 13. M. M. Plentiful diet of flesh-meat and vegetables with small-beer. Opium, from a quarter of a grain to half a grain twice a day. Sorbentia. Tincture of digitalis, thirty drops twice a day. Externally sea-bathing, or bathing in salt and water, one pound to three gallons, made warm. The application of Peruvian bark in fine powder, seven parts, and white lead, (cerussa) in fine powder one part, mixed together and applied on the ulcers in dry powder, by means of lint and a bandage, to be renewed every day. Or very fine powder of calamy alone, lapis calaminaris. If powder of manganese? 22. _Schirrus._ After the absorbent veins of a gland cease to perform their office, if the secerning arteries of it continue to act some time longer, the fluids are pushed forwards, and stagnate in the receptacles or capillary vessels of the gland; and the thinner part of them only being resumed by the absorbent system of the gland, a hard tumour gradually succeeds; which continues like a lifeless mass, till from some accidental violence it gains sensibility, and produces cancer, or suppurates. Of this kind are the schirrous glands of the breasts, of the lungs, of the mesentery, and the scrophulous tumours about the neck and the bronchocele. Another seat of schirrus is in the membranous parts of the system, as of the rectum intestinum, the urethra, the gula or throat; and of this kind is the verucca or wart, and the clavus pedum, or corns on the toes. A wen sometimes arises on the back of the neck, and sometimes between the shoulders; and by distending the tendinous fascia produces great and perpetual pain. M. M. Mercurial ointment. Cover the part with oiled silk. Extirpation. Electric shocks through the tumour. An issue into the substance of the wen. Opium. Ether externally. 23. _Schirrus recti intestini._ Schirrus of the rectum. A schirrus frequently affects a canal, and by contracting its diameter becomes a painful and deplorable disease. The canals thus obstructed are the rectum, the urethra, the throat, the gall-ducts, and probably the excretory ducts of the lymphatics, and of other glands. The schirrus of the rectum is known by the patient having pain in the part, and being only able to part with liquid feces, and by the introduction of the finger; the swelled part of the intestine is sometimes protruded downwards, and hangs like a valve, smooth and hard to the touch, with an aperture in the centre of it. See a paper on this subject by J. Sherwin. Memoirs of a London Medical Society, Vol. II. p. 9. M. M. To take but little solid food. Aperient medicines. Introduce a candle smeared with mercurial ointment. Sponge-tent. Clysters with forty drops of laudanum. Introduce a leathern canula, or gut, and then either a wooden maundril, or blow it up with air, so as to distend the contracted part as much as the patient can bear. Or spread mercurial plaster on thick soft leather, and roll it up with the plaster outwards to any thickness and length, which can be easily introduced and worn; or two or three such pieces may be introduced after each other. The same may be used to compress bleeding internal piles. See Class I. 2. 1. 6. 24. _Schirrus urethræ._ Schirrus of the urethra. The passage becomes contracted by the thickened membrane, and the urine is forced through with great difficulty, and is thence liable to distend the canal behind the stricture; till at length an aperture is made, and the urine forces its way into the cellular membrane, making large sinuses. This situation sometimes continues many months, or even years, and so much matter is evacuated after making water, or at the same time, by the action of the muscles in the vicinity of the sinuses, that it has been mistaken for an increased secretion from the bladder, and has been erroneously termed a catarrh of the bladder. See a paper by Dr. R. W. Darwin in the Medical Memoirs. M. M. Distend the part gradually by catgut bougies, which by their compression will at the same time diminish the thickness of the membrane, or by bougies of elastic gum, or of horn boiled soft. The patient should gain the habit of making water slowly, which is a matter of the utmost consequence, as it prevents the distention, and consequent rupture, of that part of the urethra, which is between the stricture and the neck of the bladder. When there occurs an external ulcer in the perinæum, and the urine is in part discharged that way, the disease can not be mistaken. Otherwise from the quantity of matter, it is generally supposed to come from the bladder, or prostate gland; and the urine, which escapes from the ruptured urethra, mines its way amongst the muscles and membranes, and the patient dies tabid, owing to the want of an external orifice to discharge the matter. See Class II. 1. 4. 11. 25. _Schirrus oesophagi._ A schirrus of the throat contracts the passage so as to render the swallowing of solids impracticable, and of liquids difficult. It affects patients of all ages, but is probably most frequently produced by swallowing hard angular substances, when people have lost their teeth; by which this membrane is over distended, or torn, or otherwise injured. M. M. Put milk into a bladder tied to a canula or catheter; introduce it past the stricture, and press it into the stomach. Distend the stricture gradually by a sponge-tent fastened to the end of whale-bone, or by a plug of wax, or a spermaceti candle, about two inches long; which might be introduced, and left there with a string only fixed to it to hang out of the mouth, to keep it in its place, and to retract it by occasionally; for which purpose the string must be put through a catheter or hollow probang, when it is to be retracted. Or lastly introduce a gut fixed to a pipe; and then distend it by blowing wind into it. The swallowing a bullet with a string put through it, to retract it on the exhibition of an emetic, has also been proposed. Externally mercurial ointment has been much recommended. Poultice. Oiled silk. Clysters of broth. Warm bath of broth. Transfusion of blood into a vein three or four ounces a day? See Class III. 1. 1. 15. I directed a young woman about twenty-two years of age, to be fed with new milk put into a bladder, which was tied to a catheter, and introduced beyond the stricture in her throat; after a few days her spirits sunk, and she refused to use it further, and died. Above thirty years ago I proposed to an old gentleman, whose throat was entirely impervious, to supply him with a few ounces of blood daily from an ass, or from the human animal, who is still more patient and tractable, in the following manner. To fix a silver pipe about an inch long to each extremity of a chicken's gut, the part between the two silver ends to be measured by filling it with warm water; to put one end into the vein of a person hired for that purpose, so as to receive the blood returning from the extremity; and when the gut was quite full, and the blood running through the other silver end, to introduce that end into the vein of the patient upwards towards the heart, so as to admit no air along with the blood. And lastly, to support the gut and silver ends on a water plate, filled with water of ninety-eight degrees of heat, and to measure how many ounces of blood was introduced by passing the finger, so as to compress the gut, from the receiving pipe to the delivering pipe; and thence to determine how many gut-fulls were given from the healthy person to the patient. See Class IV. 2. 4. 11. Mr. ---- considered a day on this proposal, and then another day, and at length answered, that "he now found himself near the house of death; and that if he could return, he was now too old to have much enjoyment of life; and therefore he wished rather to proceed to the end of that journey, which he was now so near, and which he must at all events soon go, than return for so short a time." He lived but a few days afterwards, and seemed quite careless and easy about the matter. 26. _Lacteorum inirritabilitas._ Inirritability of the lacteals is described in Sect. XXVIII. under the name of paralysis of the lacteals; but as the word paralysis has generally been applied to the disobedience of the muscles to the power of volition, the name is here changed to inirritability of the lacteals, as more characteristic of the disease. 27. _Lymphaticorum inirritabilitas._ The inirritability of the cellular and cutaneous lymphatics is described in Sect. XXIX. 5. 1. and in Class I. 2. 3. 16. The inirritability of the cutaneous lymphatics generally accompanies anasarca, and is the cause of the great thirst in that malady. At the same time the cellular lymphatics act with greater energy, owing to the greater derivation of sensorial power to them in consequence of the less expenditure of it by the cutaneous ones; and hence they absorb the fat, and mucus, and also the thinner parts of the urine. Whence the great emaciation of the body, the muddy sediment, and the small quantity of water in this kind of dropsy. * * * * * ORDO II. _Decreased Irritation._ GENUS IV. _With Decreased Actions of other Cavities and Membranes._ Many of the diseases of this genus are attended with pain, and with cold extremities, both which cease on the exhibition of wine or opium; which shews, that they originate from deficient action of the affected organ. These pains are called nervous or spasmodic, are not attended with fever, but are frequently succeeded by convulsions and madness; both which belong to the class of volition. Some of them return at periods, and when these can be ascertained, a much less quantity of opium will prevent them, than is necessary to cure them, when they are begun; as the vessels are then torpid and inirritable from the want of sensorial power, till by their inaction it becomes again accumulated. Our organs of sense properly so called are not liable to pain from the absence of their appropriated stimuli, as from darkness or silence; but the other senses, which may be more properly called appetites, as those by which we perceive heat, hunger, thirst, lust, want of fresh air, are affected with pain from the defect or absence of their accustomed stimuli, as well as with pleasure by the possession of them; it is probable that some of our glands, whose sense or appetite requires or receives something from the circulating blood, as the pancreas, liver, testes, prostate gland, may be affected with aching or pain, when they cannot acquire their appropriated fluid. Wherever this defect of stimulus occurs, a torpor or inaction of the organ ensues, as in the capillaries of the skin, when exposed to cold; and in the glands, which secrete the gastric juice, when we are hungry. This torpor however, and concomitant pain, which is at first owing to defect of stimulus, is afterwards induced by other associations or catenations, and constitutes the beginning of ague fits. It must be further observed, that in the diseases of pain without fever, the pain is frequently not felt in the part where the cause of the disease resides; but is induced by sympathy with a distant part, whose irritability or sensibility is greater or less than its own. Thus a stone at the neck of the bladder, if its stimulus is not very great, only induces the pain of strangury at the glans penis. If its stimulus be greater, it then induces pain at the neck of the bladder. The concretions of bile, which are protruded into the neck of the gall-bladder, when the disease is not very great, produce pain at the other extremity of the bile-duct, which enters the duodenum immediately under the pit of the stomach; but, when the disease is great from the largeness of the bile-stone, the pain is felt in the region of the liver at the neck of the gall-bladder. It appears from hence, that the pains enumerated in this genus are consequences of the inactivity of the organ; and, as they do not occasion other diseases, should be classed according to their proximate cause, which is defective irritation; there are nevertheless other pains from defect of stimulus, which produce convulsions, and belong to Class III. 1. 1.; and others, which produce pains of some distant part by association, and belong to Class IV. 2. 2. SPECIES. 1. _Sitis._ Thirst. The senses of thirst and of hunger seem to have this connection, that the former is situated at the upper end, and the latter at the lower end of the same canal. One about the pharinx, where the oesophagus opens into the mouth, and the other about the cardia ventriculi, where it opens into the stomach. The extremities of other canals have been shewn to possess correspondent sensibilities, or irritabilities, as the two ends of the urethra, and of the common gall-duct. See IV. 2. 2. 2. and 4. The membrane of the upper end of the gullet becomes torpid, and consequently painful, when there is a deficiency of aqueous fluid in the general system; it then wants its proper stimulus. In the same manner a want of the stimulus of more solid materials at the other end of the canal, which terminates in the stomach, produces hunger; as mentioned in Sect. XIV. 8. The proximate causes of both of them therefore consist in deficient irritation, when they are considered as pains; because these pains are in consequence of the inactivity of the organ, according to the fifth law of animal causation. Sect. IV. 5. But when they are considered as desires, namely of liquid or solid aliment, their proximate cause consists in the pain of them, according to the sixth law of animal causation. So the proximate cause of the pain of coldness is the inactivity of the organ, and perhaps the consequent accumulation of sensorial power in it; but the pain itself, or the consequent volition, is the proximate cause of the shuddering and gnashing the teeth in cold fits of intermittent fevers. See Class I. 2. 2. 1. Thirst may be divided into two varieties alluding to the remote cause of each, and may be termed sitis calida, or warm thirst, and sitis frigida, or cold thirst. The remote cause of the former arises from the dissipation of the aqueous parts of our fluids by the increased secretion of perspirable matter, or other evacuations. And hence it occurs in hot fits of fever, and after taking much wine, opium, spice, salt, or other drugs of the Art. incitantia or secernentia. The thirst, which occurs about three hours after eating a couple of red herrings, to a person unaccustomed to salted meat, is of this kind; the increased action of the cutaneous vessels dissipates so much of our fluids by insensible perspiration, as to require above two quarts of water to restore the fluidity of the blood, and to wash the salt out of the system. See Art. III. 2. 1. M. M. Cold water. Vegetable acids. Warm bath. The remote cause of sitis frigida, or cold thirst, is owing to the inaction of the cutaneous, pulmonary, urinary, and cellular absorbents; whence the blood is deprived of the great supply of moisture, which it ought to receive from the atmosphere, and from the cells of the cellular membrane, and from other cysts; this cause of thirst exists in dropsies, and in the cold fits of intermittents. The desire of fluids, like that of solids, is liable to acquire periods, and may therefore readily become diseased by indulgence in liquids grateful to the palate. Of diseased thirst, the most common is either owing to defect of the action of the numerous absorbent vessels on the neck of the bladder, in which the patient makes much paleish water; or to the defective absorption of the skin and lungs, in which the patient makes but little water, and that high-coloured, and with sediment. In both the tongue and lips are liable to become very dry. The former in its greatest degree attends diabætes, and the latter anasarca. M. M. Warm water, warm wine, warm bath. Opium. Cold bath. Iced water. Lemonade. Cyder. 2. _Esuries._ Hunger has been fancifully ascribed to the sides of the stomach rubbing against each other, and to the increased acidity of the gastric juice corroding the coats of it. If either of these were the cause of hunger, inflammation must occur, when they had continued some time; but, on the contrary, coldness and not heat are attendant on hunger; which evinces, that like thirst it is owing to the inactivity of the membrane, which is the seat of it; while the abundant nerves about the cardia ventriculi, and the pain of hunger being felt in that part, gives great reason to conclude, that it is there situated. The sense of hunger as well as of thirst is liable to acquire habits in respect to the times of its returning painfulness, as well as in respect to the quantity required to satiate its appetency, and hence may become diseased by indulgence, as well as by want of its appropriate stimulus. Those who have been accustomed to distend their stomach by large quantities of animal and vegetable food, and much potation, find a want of distention, when the stomach is empty, which occasions faintness, and is mistaken for hunger, but which does not appear to be the same sensation. I was well informed, that a woman near Lichfield, who eat much animal and vegetable food for a wager, affirmed, that since distending her stomach so much, she had never felt herself satisfied with food; and had in general taken twice as much at a meal, as she had been accustomed to, before she eat so much for a wager. 3. _Nausea sicca._ Dry nausea. Consists in a quiescence or torpor of the mucous or salivary glands, and precedes their inverted motions, described in nausea humida, Class I. 3. 2. 3. In the same manner as sickness of the stomach is a quiescence of that organ preceding the action of vomiting, as explained in Sect. XXXV. 1. 3. This is sometimes induced by disagreeable drugs held in the mouth, at other times of disgustful ideas, and at other times by the association of these actions with those of the stomach; and thus according to its different proximate causes may belong to this, or to the second, or to the fourth class of diseases. M. M. Lemonade. Tasteful food. A blister. Warm bath. 4. _Ægritudo ventriculi._ Sickness of stomach is produced by the quiescence or inactivity of that organ, as is explained in Sect. XXXV. 1. 3. It consists in the state between the usual peristaltic motions of that organ, in the digestion of our aliment, and the retrograde motions of it in vomiting; for it is evident, that the direct motions of it from the cardia to the pylorus must stop, before those in a contrary direction can commence. This sickness, like the nausea above described, is sometimes produced by disgustful ideas, as when nasty objects are seen, and nasty stories related, as well as by the exhaustion of the sensorial power by the stimulus of some emetic drugs, and by the defect of the production of it, as in enfeebled drunkards. Sickness may likewise consist in the retrograde motions of the lymphatics of the stomach, which regurgitate into it the chyle or lymph, which they have lately absorbed, as in Class I. 3. 2. 3. It is probable, that these two kinds of sickness may be different sensations, though they have acquired but one name; as one of them attends hunger, and the other repletion; though either of them may possibly be induced by association with nauseous ideas. M. M. A blister on the back. An emetic. Opium. Crude mercury. Covering the head in bed. See Sect. XXV. 16. Class IV. 1. 1. 2. and 3. 5. _Cardialgia._ Heartburn originates from the inactivity of the stomach, whence the aliment, instead of being subdued by digestion, and converted into chyle, runs into fermentation, producing acetous acid. Sometimes the gastric juice itself becomes so acid as to give pain to the upper orifice of the stomach; these acid contents of the stomach, on falling on a marble hearth, have been seen to produce an effervescence on it. The pain of heat at the upper end of the gullet, when any air is brought up from the fermenting contents of the stomach, is to be ascribed to the sympathy between these two extremities of the oesophagus rather than to the pungency of the carbonic gas, or fixed air; as the sensation in swallowing that kind of air in water is of a different kind. See Class I. 3. 1. 3. and IV. 2. 2. 5. M. M. This disease arising from indigestion is often very pertinacious, and afflicting; and attended with emaciation of the body from want of sufficient chyle. As the saliva swallowed along with our food prevents its fermentation, as appears by the experiments of Pringle and Macbride, some find considerable relief by chewing parched wheat, or mastic, or a lock of wool, frequently in a day, when the pain occurs, and by swallowing the saliva thus effused; a temporary relief is often obtained from antiacids, as aerated alcaline water, Seltzer's water, calcareous earths, alcaline salts made into pills with soap, soap alone, tin, milk, bitters. More permanent use may be had from such drugs as check fermentation, as acid of vitriol; but still more permanent relief from such things as invigorate the digestion, as a blister on the back; a due quantity of vinous spirit and water taken regularly. Steel. Temperance. A sleep after dinner. A waistcoat made so tight as slightly to compress the bowels and stomach. A flannel shirt in winter, not in summer. A less quantity of potation of all kinds. Ten black pepper-corns swallowed after dinner. Half a grain of opium twice a day, or a grain. The food should consist of such things as do not easily ferment, as flesh, shell-fish, sea-biscuit, toasted cheese. I have seen toasted cheese brought up from the stomach 24 hours after it had been swallowed, without apparently having undergone any chemical change. See Class II. 1. 3. 17. and IV. 1. 2. 13. 6. _Arthritis Ventriculi._ Sickness of the stomach in gouty cases is frequently a consequence of the torpor or inflammation of the liver, and then it continues many days or weeks. But when the patient is seized with great pain at the stomach with the sensation of coldness, which they have called an ice-bolt, this is a primary affection of the stomach, and destroys the patient in a few hours, owing to the torpor or inaction of that viscus so important to life. This primary gout of the stomach, as it is a torpor of that viscus, is attended with sensation of coldness, and with real defect of heat, in that part, and may thence be distinguished from the pain occasioned by the passage of a gall-stone into the duodenum, as well as by the weak pulse, and cold extremities; to which must be added, that it affects those only, who have been long afflicted with the gout, and much debilitated by its numerous attacks. M. M. Opium. Vinous spirit. Volatile alcali. Spice. Warmth applied externally to the stomach by hot cloths or fomentation. 7. _Colica flatulenta._ The flatulent colic arises from the too great distention of the bowel by air, and consequent pain. The cause of this disease is the inactivity or want of sufficiently powerful contraction of the coats of the bowel, to carry forwards the gas given up by the fermenting aliment. It is without fever, and generally attended with cold extremities. It is distinguished, first, from the pain occasioned by the passage of a gall-stone, as that is felt at the pit of the stomach, and this nearer the navel. Secondly, it is distinguished from the colica saturnina, or colic from lead, as that arising from the torpor of the liver, or of some other viscus, is attended with greater coldness, and with an aching pain; whereas the flatulent cholic being owing to distention of the muscles of the bowel, the pain is more acute, and the coldness less. Thirdly, it is distinguished from inflammation of the bowels, or ileus, as perpetual vomiting and fever attend this. Fourthly, it is distinguished from cholera, because that is accompanied with both vomiting and diarrhoea. And lastly, from the colica epileptica, or hysteric colic, as that is liable to alternate with convulsion, and sometimes with insanity; and returns by periods. M. M. Spirit of wine and warm water, one spoonful of each. Opium one grain. Spice. Volatile alcali. Warm fomentation externally. Rhubarb. 8. _Colica saturnina._ Colic from lead. The pain is felt about the navel, is rather of an aching than acute kind at first, which increases after meals, and gradually becomes more permanent and more acute. It terminates in paralysis, frequently of the muscles of the arm, so that the hand hangs down, when the arm is extended horizontally. It is not attended with fever, or increase of heat. The seat of the disease is not well ascertained, it probably affects some part of the liver, as a pale bluish countenance and deficiency of bile sometimes attends or succeeds it, with consequent anasarca; but it seems to be caused immediately by a torpor of the intestine, whether this be a primary or secondary affection, as appears from the constipation of the bowels, which attends it; and is always produced in consequence of the great stimulus of lead previously used either internally for a length of time, or externally on a large surface. A delicate young girl, daughter of a dairy farmer, who kept his milk in leaden cisterns, used to wipe off the cream from the edges of the lead with her finger; and frequently, as she was fond of cream, licked it from her finger. She was seized with the saturnine colic, and semi-paralytic wrists, and sunk from general debility. A feeble woman about 40 years of age sprained her ancle, and bruised her leg and thigh; and applied by ill advice a solution of lead over the whole limb, as a fomentation and poultice for about a fortnight. She was then seized with the colica saturnina, lost the use of her wrists, and gradually sunk under a general debility. M. M. First opium one or two grains, then a cathartic of senna, jalap, and oil, as soon as the pain is relieved. Oleum ricini. Alum. Oil of almonds. A blister on the navel. Warm bath. The stimulus of the opium, by restoring to the bowel its natural irritability in this case of painful torpor, assists the action of the cathartic. 9. _Tympanitis._ Tympany consists in an elastic tumor of the abdomen, which sounds on being struck. It is generally attended with costiveness and emaciation. In one kind the air is said to exist in the bowels, in which case the tumor is less equal, and becomes less tense and painful on the evacuation of air. In the other kind the air exists in the cavity of the abdomen, and sometimes is in a few days exchanged for water, and the tympany becomes an ascites. Air may be distinguished in the stomach of many people by the sound on striking it with the fingers, and comparing the sound with that of a similar percussion on other parts of the bowels; but towards the end of fevers, and especially in the puerperal fever, a distention of the abdomen by air is generally a fatal symptom, though the ease, and often cheerfulness, of the patient vainly flatters the attendants. M. M. In the former case a clyster-pipe unarmed may be introduced, and left some time in the rectum, to take off the resistance of the sphincter, and thus discharge the air, as it is produced from the fermenting or putrefying aliment. For this purpose, in a disease somewhat similar in horses, a perforation is made into the rectum on one side of the sphincter; through which fistula the air, which is produced in such great excess from the quantity of vegetable food which they take, when their digestions are impaired, is perpetually evacuated. In both cases also, balsams, essential oil, spice, bandage on the abdomen, and, to prevent the fermentation of the aliment, acid of vitriol, saliva. See Class I. 2. 4. 5. 10. _Hypochondriasis._ The hypochondriac disease consists in indigestion and consequent flatulency, with anxiety or want of pleasureable sensation. When the action of the stomach and bowels is impaired, much gas becomes generated by the fermenting or putrescent aliment, and to this indigestion is catenated languor, coldness of the skin, and fear. For when the extremities are cold for too long a time in some weak constitutions, indigestion is produced by direct sympathy of the skin and the stomach, with consequent heart-burn, and flatulency. The same occurs if the skin be made cold by fear, as in riding over dangerous roads in winter, and hence conversely fear is produced by indigestion or torpor of the stomach by association. This disease is confounded with the fear of death, which is an insanity, and therefore of a totally different nature. It is also confounded with the hysteric disease, which consists in the retrograde motions of the alimentary canal, and of some parts of the absorbent system. The hypochondriasis, like chlorosis, is sometimes attended with very quick pulse; which the patient seems to bear so easily in these two maladies, that if an accidental cough attends them, they may be mistaken for pulmonary consumption; which is not owing primarily to the debility of the heart, but to its direct sympathy with the actions of the stomach. M. M. Blister. A plaster on the abdomen of Burgundy pitch. Opium a grain twice a day. Rhubarb six grains every night. Bark. Steel. Spice. Bath-water. Siesta, or sleep after dinner. Uniform hours of meals. No liquor stronger than small beer, or wine and water. Gentle exercise on horseback in the open air uniformly persisted in. See Cardialgia, I. 2. 4. 5. 11. _Cephalæa._ Head-ach frequently attends the cold paroxysm of intermittents; afflicts inebriates the day after intoxication; and many people who remain too long in the cold bath. In all which cases there is a general inaction of the whole system, and as these membranes about the head have been more exposed to the variations of heat and cold of the atmosphere, they are more liable to become affected so far as to produce sensation, than other membranes; which are usually covered either with clothes, or with muscles, as mentioned in Sect. XXXIII. 2. 10. The promptitude of the membranes about the scalp to sympathize with those of other parts of the system is so great, that this cephalæa without fever, or quickness of pulse, is more frequently a secondary than a primary disease, and then belongs to Class IV. 2. 2. 7. The hemicrania, or partial head-ach, I believe to be almost always a disease from association; though it is not impossible, but a person may take cold on one side of the head only. As some people by sitting always on the same side of the fire in winter are liable to render one side more tender than the other, and in consequence more subject to pains, which have been erroneously termed rheumatic. See Class IV. 2. 2. 7. & 8. M. M. The method of cure consists in rendering the habit more robust, by gentle constant exercise in the open air, flesh diet, small beer at meals with one glass of wine, regular hours of rest and rising, and of meals. The cloathing about the head should be warmer during sleep than in the day; because at that time people are more liable to take cold; that is, the membranous parts of it are more liable to become torpid. As explained in Sect. XVIII. 15. In respect to medicine, two drams of valerian root in powder three or four times a day are recommended by Fordyce. The bark. Steel in moderate quantities. An emetic. A blister. Opium, half a grain twice a day. Decayed teeth should be extracted, particularly such as either ache, or are useless. Cold bath between 60 and 70 degrees of heat. Warm bath of 94 or 98 degrees every day for half an hour during a month. See Class IV. 2. 2. 7. and 8. A solution of arsenic, about the sixteenth part of a grain, is reported to have great effect in this disease. It should be taken thrice a day, if it produces no griping or sickness, for two or three weeks. A medicine of this kind is sold under the name of tasteless ague-drops; but a more certain method of ascertaining the quantity is delivered in the subsequent materia medica, Art. IV. 2. 6. 12. _Odontalgia._ Tooth-ach. The pain has been erroneously supposed, where there is no inflammation, to be owing to some acrid matter from a carious tooth stimulating the membrane of the alveolar process into violent action and consequent pain; but the effect seems to have been mistaken for the cause, and the decay of the tooth to have been occasioned by the torpor and consequent pain of the diseased membrane. First, because the pain precedes the decay of the tooth in regard to time, and is liable to recur, frequently for years, without certainly being succeeded at last by a carious tooth, as I have repeatedly observed. Secondly, because any stimulant drug, as pyrethrum, or oil of cloves, applied to the tooth, or ether applied externally to the cheek, so far from increasing the pain, as they would do if the pained membrane, already acted too strongly, that they frequently give immediate relief like a charm. And thirdly, because the torpor, or deficient action of the membrane, which includes the diseased tooth, occasions the motions of the membranes most connected with it, as those of the cheek and temples, to act with less than their natural energy; and hence a coldness of the cheek is perceived easily by the hand of the patient, comparing it with the other cheek; and the pain of hemicrania is often produced in the temple of the affected side. This coldness of the cheek in common tooth-ach evinces, that the pain is not then caused by inflammation; because in all inflammations so much heat is produced in the secretions of new vessels and fluids, as to give heat to the parts in vicinity. And hence, as soon as the gum swells and inflames along with the cheek, heat is produced, and the pain ceases, owing to the increased exertions of the torpid membrane, excited by the activity of the sensorial power of sensation; which previously existed in its passive state in the painful torpid membrane. See Odontitis, Class II. 1. 4. 7. and IV. 2. 2. 8. M. M. If the painful tooth be found, venesection. Then a cathartic. Afterwards two grains of opium. Camphor and opium, one grain of each held in the mouth; or a drop or two of oil of cloves put on the painful tooth. Ether. If the tooth has a small hole in it, it should be widened within by an instrument, and then stopped with leaf-gold, or leaf-lead; but should be extracted, if much decayed. It is probable that half a small drop of a strong solution of arsenic, put carefully into the hollow of a decayed aching tooth, would destroy the nerve without giving any additional pain; but this experiment requires great caution, lest any of the solution should touch the tongue or gums. Much cold or much heat are equally injurious to the teeth, which are endued with a fine sensation of this universal fluid. The best method of preserving them is by the daily use of a brush, which is not very hard, with warm water and fine charcoal dust. A lump of charcoal should be put a second time into the fire till it is red hot, as soon as it becomes cool the external ashes should be blown off, and it should be immediately reduced to fine powder in a mortar, and kept close stopped in a phial. It takes away the bad smell from decayed teeth, by washing the mouth with this powder diffused in water immediately. The putrid smell of decaying stumps of teeth may be destroyed for a time by washing the mouth with a weak solution of alum in water. If the calcareous crust upon the teeth adheres very firmly, a fine powder of pumice-stone may be used occasionally, or a tooth instrument. Acid of sea-salt, much diluted, may be used; but this very rarely, and with the greatest caution, as in cleaning sea-shells. When the gums are spongy, they should be frequently pricked with a lancet. Should black spots in teeth be cut out? Does the enamel grow again when it has been perforated or abraded? 13. _Otalgia._ Ear-ach sometimes continues many days without apparent inflammation, and is then frequently removed by filling the ear with laudanum, or with ether; or even with warm oil, or warm water. See Class II. 1. 4. 8. This pain of the ear, like hemicrania, is frequently the consequence of association with a diseased tooth; in that case the ether should be applied to the cheek over the suspected tooth, or a grain of opium and as much camphor mixed together and applied to the suspected tooth. In this case the otalgia belongs to the fourth class of diseases. 14. _Pleurodyne chronica._ Chronical pain of the side. Pains of the membranous parts, which are not attended with fever, have acquired the general name of rheumatic; which should, nevertheless, be restricted to those pains which exist only when the parts are in motion, and which have been left after inflammation of them; as described in Class I. 1. 3. 12. The pain of the side here mentioned affects many ladies, and may possibly have been owing to the pressure of tight stays, which has weakened the action of the vessels composing some membranous part, as, like the cold head-ach, it is attended with present debility; in one patient, a boy about ten years old, it was attended with daily convulsions, and was supposed to have originated from worms. The disease is very frequent, and generally withstands the use of blisters on the part; but in some cases I have known it removed by electric shocks repeated every day for a fortnight through the affected side. Pains of the side may be sometimes occasioned by the adhesion of the lungs to the pleura, after an inflammation of them; or to the adhesion of some abdominal viscera to their cavity, or to each other; which also are more liable to affect ladies from the unnatural and ungraceful pressure of tight stays, or by sitting or lying too long in one posture. But in these cases the pain should be more of the smarting, than of the dull kind. M. M. Ether. A blister. A plaster of Burgundy pitch. An issue or seton on the part. Electric shocks. Friction on the part with oil and camphor. Loose dress. Frequent change of posture both in the day and night. Internally opium, valerian, bark. 15. _Sciatica frigida._ Cold sciatica. The pain along the course of the sciatic nerve, from the hip quite down to the top of the foot, when it is not attended with fever, is improperly termed either rheumatism or gout; as it occurs without inflammation, is attended with pain when the limb is at rest; and as the pain attends the course of the nerve, and not the course of the muscles, or of the fascia, which contains them. The theory of Cotunnius, who believed it to be a dropsy of the sheath of the nerve, which was compressed by the accumulated fluid, has not been confirmed by dissection. The disease seems to consist of a torpor of this sheath of the nerve, and the pain seems to be in consequence of this torpor. See Class II. 1. 2. 18. M. M. Venesection. A cathartic. And then one grain of calomel and one of opium every night for ten successive nights. And a blister, at the same time, a little above the knee-joint on the outside of the thigh, where the sciatic nerve is not so deep seated. Warm bath. Cold bath. Cover the limb with oiled silk, or with a plaster-bandage of emplastrum de minio. 16. _Lumbago frigida._ Cold lumbago. When no fever or inflammation attends this pain of the loins, and the pain exists without motion, it belongs to this genus of diseases, and resembles the pain of the loins in the cold fit of ague. As these membranes are extensive, and more easily fall into quiescence, either by sympathy, or when they are primarily affected, this disease becomes very afflicting, and of great pertinacity. See Class II. 1. 2. 17. M. M. Venesection. A cathartic. Issues on the loins. Adhesive plaster on the loins. Blister on the os sacrum. Warm bath. Cold bath. Remove to a warmer climate in the winter. Loose dress about the waist. Friction daily with oil and camphor. 17. _Hysteralgia frigida._ Cold pain of the uterus preceding or accompanying menstruation. It is attended with cold extremities, want of appetite, and other marks of general debility. M. M. A clyster of half a pint of gruel, and 30 drops of laudanum; or a grain of opium and six grains of rhubarb every night. To sit over warm water, or go into a warm bath. 18. _Proctalgia frigida._ Cold pain at the bottom of the rectum previous to the tumor of the piles, which sometimes extends by sympathy to the loins; it seems to be similar to the pain at the beginning of menstruation, and is owing to the torpor or inirritability of the extremity of the alimentary canal, or to the obstruction of the blood in its passage through the liver, when that viscus is affected, and its consequent delay in the veins of the rectum, occasioning tumors of them, and dull sensations of pain. M. M. Calomel. A cathartic. Spice. Clyster, with 30 drops of laudanum. Sitting over warm water. If chalybeates after evacuation? See Class I. 2. 3. 23. and I. 2. 1. 6. 19. _Vesicæ felleæ inirritabilitas._ The inirritability of the gall-bladder probably occasions one kind of _icterus_, or jaundice; which is owing to whatever obstructs the passage of bile into the duodenum. The jaundice of aged people, and which attends some fevers, is believed to be most frequently caused by an irritative palsy of the gall-bladder; on which account the bile is not pressed from the cyst by its contraction, as in a paralysis of the urinary bladder. A thickening of the coats of the common bile-duct by inflammation or increased action of their vessels so as to prevent the passage of the bile into the intestine, in the same manner as the membrane, which lines the nostrils, becomes thickened in catarrh so as to prevent the passage of air through them, is probably another frequent cause of jaundice, especially of children; and generally ceases in about a fortnight, like a common catarrh, without the aid of medicine; which has given rise to the character, which charms have obtained in some countries for curing the jaundice of young people. The spissitude of the bile is another cause of jaundice, as mentioned in Class I. 1. 3. 8. This also in children is a disease of little danger, as the gall-ducts are distensible, and will the easier admit of the exclusion of gall-stones; but becomes a more serious disease in proportion to the age of the patient, and his habits of life in respect to spirituous potation. A fourth cause of jaundice is the compression of the bile-duct by the enlargement of an inflamed or schirrous liver; this attends those who have drank much spirituous liquor, and is generally succeeded by dropsy and death. M. M. Repeated emetics. Mild cathartics. Warm bath. Electricity. Bitters. Then steel, which, when the pain and inflammation is removed by evacuations, acts like a charm in removing the remainder of the inflammation, and by promoting the absorption of the new vessels or fluids; like the application of any acrid eye-water at the end of ophthalmia; and thus the thickened coats of the bile-duct become reduced, or the enlargement of the liver lessened, and a free passage is again opened for the bile into the intestine. Ether with yolk of egg is recommended, as having a tendency to dissolve inspissated bile. And a decoction of madder is recommended for the same purpose; because the bile of animals, whose food was mixed with madder, was found always in a dilute state. Aerated alcaline water, or Seltzer's water. Raw cabbage, and other acrid vegetables, as water-cresses, mustard. Horses are said to be subject to inspissated bile, with yellow eyes, in the winter season, and to get well as soon as they feed on the spring grass. The largest bile-stone I have seen was from a lady, who had parted with it some years before, and who had abstained above ten years from all kinds of vegetable diet to prevent, as she supposed, a colic of her stomach, which was probably a pain of the biliary duct; on resuming the use of some vegetable diet, she recovered a better state of health, and formed no new bilious concretions. A strong aerated alcaline water is sold by J. Schweppe, No. 8, King's-street, Holborn. See Class I. 1. 3. 10. 20. _Pelvis renalis inirritabilitas._ Inirritability of the pelvis of the kidney. When the nucleus of a stone, whether it be inspissated mucus, or other matter, is formed in the extremity of any of the tubuli uriniferi, and being detached from thence falls into the pelvis of the kidney, it is liable to lodge there from the want of due irritability of the membrane; and in that situation increases by new appositions of indurated animal matter, in the same manner as the stone of the bladder. This is the general cause of hæmorrhage from the kidney; and of obtuse pain in it on exercise; or of acute pain, when the stone advances into the ureter. See Class I. 1. 3. 9. * * * * * ORDO II. _Decreased Irritation._ GENUS V. _Decreased Action of the Organs of Sense._ SPECIES. 1. _Stultitia inirritabilis._ Folly from inirritability. Dulness of perception. When the motions of the fibrous extremities of the nerves of sense are too weak to excite sensation with sufficient quickness and vigour. The irritative ideas are nevertheless performed, though perhaps in a feeble manner, as such people do not run against a post, or walk into a well. There are three other kinds of folly; that from deficient sensation, from deficient volition, and from deficient association, as will be mentioned in their places. In delirium, reverie, and sleep, the power of perception is abolished from other causes. 2. _Visus imminutus._ Diminished vision. In our approach to old age our vision becomes imperfect, not only from the form of the cornea, which becomes less convex, and from its decreased transparency mentioned in Class I. 2. 3. 26.; but also from the decreased irritability of the optic nerve. Thus, in the inirritative or nervous fever, the pupil of the eye becomes dilated; which in this, as well as in the dropsy of the brain, is generally a fatal symptom. A part of the cornea as well as a part of the albuginea in these fevers is frequently seen during sleep; which is owing to the inirritability of the retina to light, or to the general paresis of muscular action, and in consequence to the less contraction of the sphincter of the eye, if it may be so called, at that time. There have been instances of some, who could not distinguish certain colours; and yet whose eyes, in other respects, were not imperfect. Philos. Transact. Which seems to have been owing to the want of irritability, or the inaptitude to action, of some classes of fibres which compose the retina. Other permanent defects depend on the diseased state of the external organ. Class I. 1. 3. 14. I. 2. 3. 25. IV. 2. 1. 11. 3. _Muscæ volitantes._ Dark spots appearing before the eyes, and changing their apparent place with the motions of the eyes, are owing to a temporary defect of irritability of those parts of the retina, which have been lately exposed to more luminous objects than the other parts of it, as explained in Sect. XL. 2. Hence dark spots are seen on the bed-clothes by patients, when the optic nerve is become less irritable, as in fevers with great debility; and the patients are perpetually trying to pick them off with their fingers to discover what they are; for these parts of the retina of weak people are sooner exhausted by the stimulus of bright colours, and are longer in regaining their irritability. Other kinds of ocular spectra, as the coloured ones, are also more liable to remain in the eyes of people debilitated by fevers, and to produce various hallucinations of sight. For after the contraction of a muscle, the fibres of it continue in the last situation, till some antagonist muscles are exerted to retract them; whence, when any one is much exhausted by exercise, or by want of sleep, or in fevers, it is easier to let the fibres of the retina remain in their last situation, after having been stimulated into contraction, than to exert any antagonist fibres to replace them. As the optic nerves at their entrance into the eyes are each of them as thick as a crow-quill, it appears that a great quantity of sensorial power is expended during the day in the perpetual activity of our sense of vision, besides that used in the motions of the eye-balls and eyelids; as much I suppose as is expended in the motions of our arms, which are supplied with nerves of about the same diameters. From hence we may conclude, that the light should be kept from patients in fevers with debility, to prevent the unnecessary exhaustion of the sensorial power. And that on the same account their rooms should be kept silent as well as dark; that they should be at rest in an horizontal posture; and be cooled by a blast of cool air, or by washing them with cold water, whenever their skins are warmer than natural. 4. _Strabismus._ Squinting is generally owing to one eye being less perfect than the other; on which account the patient endeavours to hide the worst eye in the shadow of the nose, that his vision by the other may not be confused. Calves, which have an hydatide with insects inclosed in it in the frontal sinus on one side, turn towards the affected side; because the vision on that side, by the pressure of the hydatide, becomes less perfect; and the disease being recent, the animal turns round, expecting to get a more distinct view of objects. In the hydrocephalus internus, where both eyes are not become insensible, the patient squints with only one eye, and views objects with the other, as in common strabismus. In this case it may be known on which side the disease exists, and that it does not exist on both sides of the brain; in such circumstances, as the patients I believe never recover as they are now treated, might it not be adviseable to perforate the cranium over the ventricule of the affected side? which might at least give room and stimulus to the affected part of the brain? M. M. If the squinting has not been confirmed by long habit, and one eye be not much worse than the other, a piece of gauze stretched on a circle of whale-bone, to cover the best eye in such a manner as to reduce the distinctness of vision of this eye to a similar degree of imperfection with the other, should be worn some hours every day. Or the better eye should be totally darkened by a tin cup covered with black silk for some hours daily, by which means the better eye will be gradually weakened by the want of use, and the worse eye will be gradually strengthened by using it. Covering an inflamed eye in children for weeks together, is very liable to produce squinting, for the same reason. 5. _Amaurosis._ Gutta serena. Is a blindness from the inirritability of the optic nerve. It is generally esteemed a palsy of the nerve, but should rather be deemed the death of it, as paralysis has generally been applied to a deprivation only of voluntary power. This is a disease of dark eyes only, as the cataract is a disease of light eyes only. At the commencement of this disease, very minute electric shocks should be repeatedly passed through the eyes; such as may be produced by putting one edge of a piece of silver the size of a half-crown piece beneath the tongue, and one edge of a piece of zinc of a similar size between the upper lip and the gum, and then repeatedly bringing their exterior edges into contact, by which means very small electric sparks become visible in the eyes. See additional note at the end of the first volume, p. 567. and Sect. XIV. 5. M. M. Minute electric shocks. A grain of opium, and a quarter of a grain of corrosive sublimate of mercury, twice a day for four or six weeks. Blister on the crown of the head. 6. _Auditus imminutus._ Diminished hearing. Deafness is a frequent symptom in those inflammatory or sensitive fevers with debility, which are generally called putrid; it attends the general stupor in those fevers, and is rather esteemed a salutary sign, as during this stupor there is less expenditure of sensorial power. In fevers of debility without inflammation, called nervous fevers, I suspect deafness to be a bad symptom, arising like the dilated pupil from a partial paralysis of the nerve of sense. See Class IV. 2. 1. 15. Nervous fevers are supposed by Dr. Gilchrist to originate from a congestion of serum or water in some part of the brain, as many of the symptoms are so similar to those of hydrocephalus internus, in which a fluid is accumulated in the ventricules of the brain; on this idea the inactivity of the optic or auditory nerves in these fevers may arise from the compression of the effused fluid; while the torpor attending putrid fever may depend on the meninges of the brain being thickened by inflammation, and thus compressing it; now the new vessels, or the blood, which thickens inflamed parts, is more frequently reabsorbed, than the effused fluid from a cavity; and hence the stupor in one case is less dangerous than in the other. In inflammatory or sensitive fevers with debility, deafness may sometimes arise from a greater secretion and absorption of the ear-wax, which is very similar to the bile, and is liable to fill the meatus auditorius, when it is too viscid, as bile obstructs the gall-ducts. M. M. In deafness without fever Dr. Darwin applied a cupping-glass on the ear with good effect, as described in Phil. Trans. Vol. LXIV. p. 348. Oil, ether, laudanum, dropped into the ears. 7. _Olfactus imminutus._ Inactivity of the sense of smell. From our habits of trusting to the art of cookery, and not examining our food by the smell as other animals do, our sense of smell is less perfect than theirs. See Sect. XVI. 5. Class IV. 2. 1. 16. M. M. Mild errhines. 8. _Gustus imminutus._ Want of taste is very common in fevers, owing frequently to the dryness or scurf of the tongue, or external organ of that sense, rather than to any injury of the nerves of taste. See Class. I. 1. 3. 1. IV. 2. 1. 16. M. M. Warm subacid liquids taken frequently. 9. _Tactus imminutus._ Numbness is frequently complained of in fevers, and in epilepsy, and the touch is sometimes impaired by the dryness of the cuticle of the fingers. See Class IV. 2. 1. 16. When the sense of touch is impaired by the compression of the nerve, as in sitting long with one thigh crossed over the other, the limb appears larger, when we touch it with our hands, which is to be ascribed to the indistinctness of the sensation of touch, and may be explained in the same manner as the apparent largeness of objects seen through a mist. In this last case the minute parts of an object, as suppose of a distant boy, are seen less distinctly, and therefore we instantly conceive them to be further from the eye, and in consequence that the whole subtends a larger angle, and thus we believe the boy to be a man. So when any one's fingers are pressed on a benumbed limb, the sensation produced is less than it should be, judging from visible circumstances; we therefore conceive, that something intervened between the object and the sense, for it is felt as if a blanket was put between them; and that not being visibly the case, we judge that the limb is swelled. The sense of touch is also liable to be deceived from the acquired habits of one part of it acting in the vicinity of another part of it. Thus if the middle finger be crossed over either of the fingers next to it, and a nut be felt by the two ends of the fingers so crossed at the same time, the nut appears as if it was two nuts. And lastly, the sense of touch is liable to be deceived by preconceived ideas; which we believe to be excited by external objects, even when we are awake. It has happened to me more than once, and I suppose to most others, to have put my hands into an empty bason standing in an obscure corner of a room to wash them, which I believed to contain cold water, and have instantly perceived a sensation of warmth, contrary to that which I expected to have felt. In some paralytic affections, and in cold fits of ague, the sensation of touch has been much impaired, and yet that of heat has remained, See Sect. XIV. 6. M. M. Friction alone, or with camphorated oil, warm bath. Ether. Volatile alcali and water. Internally spice, salt. Incitantia. Secernentia. 10. _Stupor._ The stupor, which occurs in fevers with debility, is generally esteemed a favourable symptom; which may arise from the less expenditure of sensorial power already existing in the brain and nerves, as mentioned in species 6 of this genus. But if we suppose, that there is a continued production of sensorial power, or an accumulation of it in the torpid parts of the system, which is not improbable, because such a production of it continues during sleep, to which stupor is much allied, there is still further reason for believing it to be a favourable symptom in inirritable fevers; and that much injury is often done by blisters and other powerful stimuli to remove the stupor. See Sect. XII. 7. 8. and XXXIII. 1. 4. Dr. Blane in his Croonian Lecture on muscular motion for 1788, among many other ingenious observations and deductions, relates a curious experiment on salmon, and other fish, and which he repeated upon eels with similar event. "If a fish, immediately upon being taken out of the water, is stunned by a violent blow on the head, or by having the head crushed, the irritability and sweetness of the muscles will be preserved much longer, than if it had been allowed to die with the organs of sense entire. This is so well known to fishermen, that they put it in practice, in order to make them longer susceptible of the operation called _crimping_. A salmon is one of the fish least tenacious of life, insomuch, that it will lose all signs of life in less than half an hour after it is taken out of the water, if suffered to die without any farther injury; but if, immediately after being caught, it receives a violent blow on the head, the muscles will shew visible irritability for more than twelve hours afterwards." Dr. Blane afterwards well remarks, that "in those disorders in which the exercise of the senses is in a great measure destroyed, or suspended, as in the hydrocephalus, and apoplectic palsy, it happens not uncommonly, that the appetite and digestion are better than in health." * * * * * ORDO III. _Retrograde Irritative Motions._ GENUS I. _Of the Alimentary Canal._ The retrograde motions of our system originate either from defect of stimulus, or from defect of irritability. Thus sickness is often induced by hunger, which is a want of stimulus; and from ipecacuanha, in which last case it would seem, that the sickness was induced after the violence of the stimulus was abated, and the consequent torpor had succeeded. Hence spice, opium, or food relieves sickness. The globus hystericus, salivation, diabætes, and other inversions of motion attending hysteric paroxysms, seem to depend on the want of irritability of those parts of the body, because they are attended with cold extremities, and general debility, and are relieved by wine, opium, steel, and flesh diet; that is, by any additional stimulus. When the longitudinal muscles are fatigued by long action, or are habitually weaker than natural, the antagonist muscles replace the limb by stretching it in a contrary direction; and as these muscles have had their actions associated in synchronous tribes, their actions cease together. But as the hollow muscles propel the fluids, which they contain, by motions associated in trains; when one ring is fatigued from its too great debility, and brought into retrograde action; the next ring, and the next, from its association in train falls into retrograde action. Which continue so long as they are excited to act, like the tremors of the hands of infirm people, so long as they endeavour to act. Now as these hollow muscles are perpetually stimulated, these retrograde actions do not cease as the tremors of the longitudinal muscles, which are generally excited only by volition. Whence the retrograde motions of hollow muscles depend on two circumstances, in which they differ from the longitudinal muscles, namely, their motions being associated in trains, and their being subject to perpetual stimulus. For further elucidation of the cause of this curious source of diseases, see Sect. XXIX. 11. 5. The fluids disgorged by the retrograde motions of the various vascular muscles may be distinguished, 1. From those, which are produced by secretion, by their not being attended by increase of heat, which always accompanies increased secretion. 2. They may be distinguished from those fluids, which are the consequence of deficient absorption, by their not possessing the saline acrimony, which those fluids possess; which inflames the skin or other membranes on which they fall; and which have a saline taste to the tongue. 3. They may be distinguished from those fluids, which are the consequence both of increased secretion and absorption, as these are attended with increase of warmth, and are inspissated by the abstraction of their aqueous parts. 4. Where chyle, or milk, are found in the feces or urine, or when other fluids, as matter, are translated from one part of the system to another, they have been the product of retrograde action of lymphatic or other canals. As explained in Sect. XXIX. 8. SPECIES. 1. _Ruminatio._ In the rumination of horned cattle the retrograde motions of the oesophagus are visible to the eye, as they bring up the softened grass from their first stomach. The vegetable aliment in the first stomach of cattle, which have filled themselves too full of young clover, is liable to run into fermentation, and distend the stomach, so as to preclude its exit, and frequently to destroy the animal. To discharge this air the farmers frequently make an opening into the stomach of the animal with success. I was informed, I believe by the late Dr. Whytt of Edinburgh, that of twenty cows in this situation two had died, and that he directed a pint of gin or whisky, mixed with an equal quantity of water, to be given to the other eighteen; all of which eructed immense quantities of air, and recovered. There are histories of ruminating men, and who have taken pleasure in the act of chewing their food a second time. Philos. Transact. 2. _Ructus._ Eructation. An inverted motion of the stomach excluding through its upper valve an elastic vapour generated by the fermentation of the aliment; which proceeds so hastily, that the digestive power does not subdue it. This is sometimes acquired by habit, so that some people can eruct when they please, and as long as they please; and there is gas enough generated to supply them for this purpose; for by Dr. Hale's experiments, an apple, and many other kinds of aliment, give up above six hundred times their own bulk of an elastic gas in fermentation. When people voluntarily eject the fixable air from their stomachs, the fermentation of the aliment proceeds the faster; for stopping the vessels, which contain new wines, retards their fermentation, and opening them again accelerates it; hence where the digestion is impaired, and the stomach somewhat distended with air, it is better to restrain than to encourage eructations, except the quantity makes it necessary. When wine is confined in bottles the fermentation still proceeds slowly even for years, till all the sugar is converted into spirit; but in the process of digestion, the saccharine part is absorbed in the form of chyle by the bibulous mouths of the numerous lacteals, before it has time to run into the vinous fermentation. 3. _Apepsia._ Indigestion. Water-qualm. A few mouthfuls of the aliment are rejected at a time for some hours after meals. When the aliment has had time to ferment, and become acid, it produces cardialgia, or heart-burn. This disease is perhaps generally left after a slight inflammation of the stomach, called a surfeit, occasioned by drinking cold liquors, or eating cold vegetables, when heated with exercise. This inflammation of the stomach is frequently, I believe, at its commencement removed by a critical eruption on the face, which differs in its appearance as well as in its cause from the gutta rosea of drunkards, as the skin round the base of each eruption is less inflamed. See Class II. 1. 4. 6.. This disease differs from Cardialgia, Class I. 2. 4. 5. in its being not uniformly attended with pain of the cardia ventriculi, and from its retrograde motions of a part of the stomach about the upper orifice of it. In the same manner as hysteria differs from hypochondriasis; the one consisting in the weakness and indigestion of the same portions of the alimentary canal, and the other in the inverted motions of some parts of it. This apepsia or water-qualm continues many years, even to old age; Mr. G---- of Lichfield suffered under this disease from his infancy; and, as he grew old, found relief only from repeated doses of opium. M. M. A blister, rhubarb, a grain of opium twice a day. Soap, iron-powder. Tin-powder. 4. _Vomitus._ An inverted order of the motions of the stomach and oesophagus with their absorbent vessels, by which their contents are evacuated. In the act of vomiting less sensorial power is employed than in the usual peristaltic motion of the stomach, as explained in Sect. XXXV. 1. 3. Whence after the operation of an emetic the digestion becomes stronger by an accumulation of sensorial power during its decreased action. This decreased action of the stomach may be either induced by want of stimulus, as in the sickness which attends hunger; or it may be induced by temporary want of irritability, as in cold fits of fever; or from habitual want of irritability, as the vomiting of enfeebled drunkards. Or lastly, by having been previously too violently stimulated by an emetic drug, as by ipecacuanha. M. M. A blister. An emetic. Opium. Warmth of a bed, covering the face for a while with the bed-clothes. Crude mercury. A poultice with opium or theriaca externally. 5. _Cholera._ When not only the stomach, as in the last article, but also the duodenum, and ilium, as low as the valve of the colon, have their motions inverted; and great quantities of bile are thus poured into the stomach; while at the same time some branches of the lacteals become retrograde, and disgorge their contents into the upper part of the alimentary canal; and other branches of them disgorge their contents into the lower parts of it beneath the valve of the colon; a vomiting and purging commence together, which is called cholera, as it is supposed to have its origin from increased secretion of bile; but I suppose more frequently arises from putrid food, or poisonous drugs, as in the case narrated in Sect. XXV. 13. where other circumstances of this disease are explained. See Class II. 1. 2. 11. The cramps of the legs, which are liable to attend cholera, are explained in Class III. 1. 1. 14. 6. _Ileus._ Consists in the inverted motions of the whole intestinal canal, from the mouth to the anus; and of the lacteals and absorbents which arise from it. In this pitiable disease, through the valve of the colon, through the pylorus, the cardia, and the pharinx, are ejected, first, the contents of the stomach and intestines, with the excrement and even clysters themselves; then the fluid from the lacteals, which is now poured into the intestines by their retrograde motions, is thrown up by the mouth; and, lastly, every fluid, which is absorbed by the other lymphatic branches, from the cellular membrane, the skin, the bladder, and all other cavities of the body; and which is then poured into the stomach or intestines by the retrograde motions of the lacteals; all which supply that amazing quantity of fluid, which is in this disease continually ejected by vomiting. See Sect. XXV. 15. for a further explanation of this disease. M. M. Copious venesection. Twenty grains of calomel in small pills, or one grain of aloe every hour till stools are procured. Blisters. Warm bath. Crude mercury. Clyster of ice-water. Smear the skin all over with grease, as mentioned in Sect. XXV. 15. As this malady is occasioned sometimes by an introsusception of a part of the intestine into another part of it, especially in children, could holding them up by their heels for a second or two of time be of service after venesection? Or the exhibition of crude quicksilver two ounces every half hour, till a pound is taken, be particularly serviceable in this circumstance? Or could half a pound, or a pound, of crude mercury be injected as a clyster, the patient being elevated by the knees and thighs so as to have his head and shoulders much lower than his bottom, or even for a short time held up by the heels? Could this also be of advantage in strangulated hernia? Where the disease is owing to strangulated hernia, the part should be sprinkled with cold water, or iced water, or salt and water recently mixed, or moistened with ether. In cases of strangulated hernia, could acupuncture, or puncture with a capillary trocar, be used with safety and advantage to give exit to air contained in the strangulated bowel? Or to stimulate it into action? It is not uncommon for bashful men to conceal their being afflicted with a small hernia, which is the cause of their death; this circumstance should therefore always be enquired into. Is the seat or cause of the ileus always below the valve of the colon, and that of the cholera above it? See Class II. 1. 2. 11. 7. _Globus hystericus._ Hysteric suffocation is the perception of a globe rolling round in the abdomen, and ascending to the stomach and throat, and there inducing strangulation. It consists of an ineffectual inversion of the motions of the oesophagus, and other parts of the alimentary canal; nothing being rejected from the stomach. M. M. Tincture of castor. Tinct. of opium of each 15 drops. See Hysteria, Class I. 3. 1. 10. 8. _Vomendi conamen inane._ An ineffectual effort to vomit. It frequently occurs, when the stomach is empty, and in some cases continues many hours; but as the lymphatics of the stomach are not inverted at the same time, there is no supply of materials to be ejected; it is sometimes a symptom of hysteria, but more frequently attends irregular epilepsies or reveries; which however may be distinguished by their violence of exertion, for the exertions of hysteric motions are feeble, as they are caused by debility; but those of epilepsies, as they are used to relieve pain, are of the most violent kind; insomuch that those who have once seen these ineffectual efforts to vomit in some epilepsies, can never again mistake them for symptoms of hysteria. See a case in Sect. XIX. 2. M. M. Blister. Opium. Crude mercury. 9. _Borborigmus._ A gurgling of the bowels proceeds from a partial invertion of the peristaltic motions of them, by which the gas is brought into a superior part of the bowel, and bubbles through the descending fluid, like air rushing into a bottle as the water is poured out of it. This is sometimes a distressing symptom of the debility of the bowels joined with a partial inversion of their motions. I attended a young lady about sixteen, who was in other respects feeble, whose bowels almost incessantly made a gurgling noise so loud as to be heard at a considerable distance, and to attract the notice of all who were near her. As this noise never ceased a minute together for many hours in a day, it could not be produced by the uniform descent of water, and ascent of air through it, but there must have been alternately a retrograde movement of a part of the bowel, which must again have pushed up the water above the air; or which might raise a part of the bowel, in which the fluid was lodged, alternately above and below another portion of it; which might readily happen in some of the curvatures of the smaller intestines, the air in which might be moved backward and forward like the air-bubble in a glass-level. M. M. Essential oil. Ten corns of black pepper swallowed whole after dinner, that its effect might be slower and more permanent; a small pipe occasionally introduced into the rectum to facilitate the escape of the air. Crude mercury. See Class I. 2. 4. 9. 10. _Hysteria._ The three last articles, together with the lymphatic diabætes, are the most common symptoms of the hysteric disease; to which sometimes is added the lymphatic salivation, and fits of syncope, or convulsion, with palpitation of the heart (which probably consists of retrograde motions of it), and a great fear of dying. Which last circumstance distinguishes these convulsions from the epileptic ones with greater certainty than any other single symptom. The pale copious urine, cold skin, palpitation, and trembling, are the symptoms excited by great fear. Hence in hysteric diseases, when these symptoms occur, the fear, which has been usually associated with them, recurs at the same time, as in hypochondriasis, Class I. 2. 4. 10. See Sect. XVI. 8. 1. The convulsions which sometimes attend the hysteric disease, are exertions to relieve pain, either of some torpid, or of some retrograde organ; and in this respect they resemble epileptic convulsions, except that they are seldom so violent as entirely to produce insensibility to external stimuli; for these weaker pains cease before the total exhaustion of sensorial power is produced, and the patient sinks into imperfect syncope; whereas the true epilepsy generally terminates in temporary apoplexy, with perfect insensibility to external objects. These convulsions are less to be dreaded than the epileptic ones, as they do not originate from so permanent a cause. The great discharge of pale urine in this disease is owing to the inverted motions of the lymphatics, which arise about the neck of the bladder, as described in Sect. XXIX. 4. 5. And the lymphatic salivation arises from the inverted motions of the salivary lymphatics. Hysteria is distinguished from hypochondriasis, as in the latter there are no retrograde motions of the alimentary canal, but simply a debility or inirritability of it, with distention and flatulency. It is distinguished from apepsia and cardialgia by there being nothing ejected from the stomach by the retrograde motions of it, or of the oesophagus. M. M. Opium. Camphor. Assafoetida. Castor, with sinapisms externally; to which must be added a clyster of cold water, or iced water; which, according to Mons. Pomme, relieves these hysteric symptoms instantaneously like a charm; which it may effect by checking the inverted motions of the intestinal canal by the torpor occasioned by cold; or one end of the intestinal canal may become strengthened, and regain its peristaltic motion by reverse sympathy, when the other end is rendered torpid by ice-water. (Pomme des Affections Vaporeuses, p. 25.) These remove the present symptoms; and bark, steel, exercise, coldish bath, prevent their returns. See Art. VI. 2. 1. 11. _Hydrophobia._ Dread of water occasioned by the bite of a mad dog, is a violent inversion of the motions of the oesophagus on the contact or even approach of water or other fluids. The pharinx seems to have acquired the sensibility of the larinx in this disease, and is as impatient to reject any fluid, which gets into it. Is not the cardia ventriculi the seat of this disease? As in cardialgia the pain is often felt in the pharinx, when the acid material stimulates the other end of the canal, which terminates in the stomach. As this fatal disease resembles tetanus, or locked jaw, in its tendency to convulsion from a distant wound, and affects some other parts by association, it is treated of in Class III. 1. 1. 15. and IV. 1. 2. 7. * * * * * ORDO III. _Retrograde Irritative Motions._ GENUS II. _Of the Absorbent System._ SPECIES. 1. _Catarrhus lymphaticus._ Lymphatic catarrh. A periodical defluxion of a thin fluid from the nostrils, for a few hours, occasioned by the retrograde motions of their lymphatics; which may probably be supplied with fluid by the increased absorption of some other lymphatic branches in their vicinity. It is distinguished from that mucous discharge, which happens in frosty weather from decreased absorption, because it is less salt to the taste; and from an increased secretion of mucus, because it is neither so viscid, nor is attended with heat of the part. This complaint is liable to recur at diurnal periods, like an intermittent fever, for weeks and months together, with great sneezing and very copious discharge for an hour or two. I have seen two of these cases, both of which occurred in delicate women, and seemed an appendage to other hysteric symptoms; whence I concluded, that the discharge was occasioned by the inverted motions of the lymphatics of the nostrils, like the pale urine in hysteric cases; and that they might receive this fluid from some other branches of lymphatic vessels opening into the frontal or maxillary cavities in their vicinity. Could such a discharge be produced by strong errhines, and excite an absorption of the congestion of lymph in the dropsy of the brain? 2. _Salivatio lymphatica._ Lymphatic salivation. A copious expuition of a pellucid insipid fluid, occasioned by the retrograde motions of the lymphatics of the mouth. It is sometimes periodical, and often attends the hysteric disease, and nervous fevers; but is not accompanied with a saline taste, or with heat of the mouth, or nausea. 3. _Nausea humida._ Moist nausea consists in a discharge of fluid, owing to the retrograde motions of the lymphatics about the fauces, without increase of heat, or saline taste, together with some retrograde motions of the fauces or pharinx; along with this nausea a sickness generally precedes the act of vomiting; which may consist of a similar discharge of mucus or chyle into the stomach by the retrograde motions of the lymphatics or lacteals, which open into it. See Class I. 2. 4. 3. and I. 2. 4. 4. M. M. Subacid liquids. Wine. Opium. A blister. 4. _Diarrhoea lymphatica._ Lymphatic diarrhoea. A quantity of mucus and lymph are poured into the intestines by the inverted motions of the intestinal lymphatics. The feces are less fetid and more liquid; and it sometimes portends the commencement of a diabætes, or dropsy, or their temporary relief. This lymphatic diarrhoea sometimes becomes chronical, in which the atmospheric moisture, absorbed by the cutaneous and pulmonary lymphatics, is poured into the intestines by the retrograde motions of the lacteals. See Section XXIX. 4. 6. where some cases of this kind are related. 5. _Diarrhoea chylifera, coeliaca._ Chyliferous diarrhoea. The chyle drank up by the lacteals of the upper intestines is poured into the lower ones by the retrograde motions of their lacteals, and appears in the dejections. This circumstance occurs at the beginning of diarrhoea crapulosa, where the patient has taken and digested more aliment than the system can conveniently receive, and thus eliminates a part of it; as appears when there is curdled chyle in some of the dejections. See Sect. XXIX. 4. 7. It differs from the lymphatic diarrhoea, as the chyliferous diabætes differs from the aqueous and mucaginous diabætes. 6. _Diabætes._ By the retrograde motions of the urinary lymphatics, an immense quantity of fluid is poured into the bladder. It is either termed chyliferous, or aqueous, or mucaginous, from the nature of the fluid brought into the bladder; and is either a temporary disease, as in hysteric women, in the beginning of intoxication, in worm cases, or in those exposed to cold damp air, or to great fear, or anxiety, or in the commencement of some dropsies; or it becomes chronical. When the urinary lymphatics invert their motions, and pour their refluent contents into the bladder, some other branch of the absorbent system acts with greater energy to supply this fluid. If it is the intestinal branch, the chyliferous diabætes is produced: if it is the cutaneous or pulmonary branch, the aqueous diabætes is produced: and if the cellular or cystic branches, the mucaginous diabætes. In the two last the urine is pellucid, and contains no sugar. In dropsies the fluid is sometimes absorbed, and poured into the bladder by the retrograde motions of the urinary lymphatics, as during the exhibition of digitalis. In the beginning of the dropsies of infirm gouty patients, I have frequently observed, that they make a large quantity of water for one night, which relieves them for several days. In these cases the patient previously feels a fulness about the precordia, with difficult respiration, and symptoms similar to those of hysteria. Perhaps a previous defect of absorption takes place in some part of the body in those hysteric cases, which are relieved by a copious discharge of pale urine. See Diabætes explained at large, Section XXIX. 4. A discharge of blood sometimes attends the diabætes, which was occasionally a symptom of that disease in Mr. Brindley, the great navigable canal maker in this country. Which may be accounted for by the communication of a lymphatic branch with the gastric branch of the vena portarum, as discovered by J. F. Meckel. See Section XXVII. 2. M. M. Alum. Earth of Alum. Cantharides. Calomel. Bark. Steel. Rosin. Opium. See Sect. XXIX. 4. 7. _Sudor lymphaticus._ Profuse sweats from the inverted motions of the cutaneous lymphatics, as in some fainting fits, and at the approach of death; and as perhaps in the sudor anglicanus. See Sect. XXIX. 5. These sweats are glutinous to the touch, and without increased heat of the skin; if the part is not covered, the skin becomes cold from the evaporation of the fluid. These sweats without heat sometimes occur in the act of vomiting, as in Sect. XXV. 9. and are probably the cause of the cold sweaty hands of some people. As mentioned in Sect. XXIX. 4. 9. in the case of R. Davis, which he cured by frequent application of lime. Though it is possible, that cold sweaty hands may also arise from the want of due absorption of the perspirable matter effused on them, and that the coldness may be owing to the greater evaporation in consequence. The acid sweats described by Dr. Dobson, which he observed in a diabætic patient, and ascribes to the chyle effused on the skin, must be ascribed to the retrograde action of the cutaneous lymphatics. See Sect. XXIX. 6. 8. _Sudor asthmaticus._ The cold sweats in this disease only cover the head, arms, and breast, and are frequently exceedingly profuse. These sweats are owing to the inverted motions of the cutaneous lymphatics of the upper part of the body, and at the same time the increased absorption of the pulmonary absorbents: hence these sweats when profuse relieve the present fit of asthma. There is no other way to account for sweats appearing on the upper parts of the body only, but by the fluid having been absorbed by the lymphatic branch of the lungs, and effused on the skin by the retrograde movements of the cutaneous lymphatics; which join those of the lungs before they enter into the venous circulation. For if they were occasioned, as generally supposed, by the difficulty of the circulation of the blood through the lungs, the whole skin must be equally affected, both of the upper and lower parts of the body; for whatever could obstruct the circulation in the upper part of the venous system, must equally obstruct it in the lower part of it. See Sect. XXIX. 6. In the convulsive asthma these sweats do not occur; hence they may be distinguished; and might be called the hydropic asthma, and the epileptic asthma. 9. _Translatio puris._ Translation of matter from one part of the system to another can only be explained from its being absorbed by one branch of the lymphatic system, and deposited in a distant part by the retrograde motions of another branch; as mentioned Sect. XXIX. 7. 1. It is curious, that these translations of matter are attended generally, I believe, with cold fits; for less heat is produced during the retrograde action of this part of the system, as no secretion in the lymphatic glands of the affected branches can exist at the same time. Do any ineffectual retrograde motions occasion the cold fits of agues? The time when the gout of the liver ceases, and the gout in the foot commences, is attended with a cold fit, as I have observed in two instances, which is difficult to explain, without supposing the new vessels, or the matter produced on the inflamed liver, to be absorbed, and either eliminated by some retrograde motion, or carried to the newly inflamed part? See Class IV. 1. 2. 15. 10. _Translatio lactis._ Translation of milk to the bowels in puerperal fevers can only be explained by the milk being absorbed by the pectoral branch of lymphatics, and carried to the bowels by the retrograde motions of the intestinal lymphatics or lacteals. See many instances of this in Sect. XXIX. 7. 4. 11. _Translatio urinæ._ Translation of urine. There is a curious case related in the Transaction of the College of Physicians at Philadelphia, Vol. I. p. 96. of a girl, who labouring under an iscuria vomited her urine for many months; which could not be distinguished from that which was at other times drawn off by the catheter. After having taken much opium, she seems at length to have formed gravel, some of which was frequently brought up by vomiting. Dr. Senter ascribes this to the retrograde motions of the lymphatics of the stomach, and the increased ones of those of the bladder, and refers to those of Sect. XXIX. of this work; which section was first published in 1780; and to Macquire's Dictionary of Chemistry, Art. Urine. The patient above described sometimes had a discharge of urine by the navel, and at other times by the rectum, and sometimes by urinous sweats. * * * * * ORDO III. _Retrograde Irritative Motions._ GENUS III. _Of the Sanguiferous System._ SPECIES. 1. _Capillarium motus retrogressus._ In microscopic experiments it is usual to see globules of blood regurgitate from the capillary vessels again and again, before they pass through them; and not only the mouths of the veins, which arise from these capillaries, are frequently seen by microscopes to regurgitate some particles of blood during the struggles of the animal; but a retrograde motion of the blood in the veins of these animals, from the very heart to the extremities of the limbs, is observable by intervals during the distresses of the dying creature. Haller, Elem. Phys. T. i. p. 216. See Section XXIX. 3. 8. 2. _Palpitatio cordis._ May not the ineffectual and weak unequal motions of the heart in hysteric cases be ascribed to the retrograde motions of it, which continue for a short time, or terminate in syncope? See Class IV. 3. 1. 6. 3. _Anhelatio spasmodica._ In some asthmas may not the difficulty of respiration arise from the inverted action of the finer branches of the bronchia, or of the pulmonary artery or vein, like those of the capillaries above described in No. 1. of this genus? * * * * * _The Orders and Genera of the Second Class of Diseases._ * * * * * CLASS II. DISEASES OF SENSATION. ORDO I. _Increased Sensation._ GENERA. 1. With increased action of the muscles. 2. With the production of new vessels by internal membranes or glands with fever. 3. With the production of new vessels by external membranes or glands with fever. 4. With the production of new vessels by internal membranes or glands without fever. 5. With the production of new vessels by external membranes or glands without fever. 6. With fever consequent to the production of new vessels or fluids. 7. With increased action of the organs of sense. ORDO II. _Decreased Sensation._ GENERA. 1. With decreased actions of the general system. 2. With decreased actions of particular organs. ORDO III. _Retrograde Sensitive Motions._ GENERA. 1. Of the excretory ducts. * * * * * _The Orders, Genera, and Species, of the Second Class Of Diseases._ * * * * * CLASS II. DISEASES OF SENSATION. ORDO I. _Increased Sensation._ GENUS I. _With Increased Action of the Muscles._ SPECIES. 1. _Deglutitio._ Deglutition. 2. _Respiratio._ Respiration. 3. _Sternutatio._ Sneezing. 4. _Anhelitus._ Panting. 5. _Tussis ebriorum._ Cough of inebriates. 6. _Syngultus._ Hiccough. 7. _Asthma humorale._ Humoral asthma. 8. _Nictitatio sensitiva._ Winking from pain. 9. _Oscitatio et pandiculatio._ Yawning and stretching. 10. _Tenesmus._ Tenesmus. 11. _Stranguria._ Strangury. 12. _Parturitio._ Parturition. GENUS II. _With the Production of new Vessels by internal Membranes or Glands, with Fever._ SPECIES. 1. _Febris sensitiva irritata._ Sensitive irritated fever. 2. _Ophthalmia interna._ Inflammation of the eye. 3. _Phrenitis._ ---- of the brain. 4. _Peripneumonia._ ---- of the lungs. ---- _trachealis._ ---- the croup. 5. _Pleuritis._ ---- of the pleura. 6. _Diaphragmitis._ ---- of the diaphragm. 7. _Carditis._ ---- of the heart. 8. _Peritonitis._ ---- of the peritoneum. 9. _Mesenteritis._ ---- of the mesentery. 10. _Gastritis._ ---- of the stomach. 11. _Enteritis._ ---- of the bowels. 12. _Hepatitis._ ---- of the liver. 13. _Splenitis._ ---- of the spleen. 14. _Nephritis._ ---- of the kidney. 15. _Cystitis._ ---- of the bladder. 16. _Hysteritis._ ---- of the womb. 17. _Lumbago sensitiva._ ---- of the loins. 18. _Ischias._ ---- of the pelvis. 19. _Paronychia interna._ ---- beneath the nails. GENUS III. _With the Production of new Vessels by external Membranes or Glands, with Fever._ SPECIES. 1. _Febris sensitiva inirritata._ Sensitive inirritated fever. 2. _Erysipelas irritatum._ Erysipelas irritated. _----inirritatum._ ---- inirritated. ---- _sensitivum._ ---- sensitive. 3. _Tonsillitis interna._ Angina internal. ---- _superficialis._ ---- superficial. ---- _inirritata._ ---- inirritated. 4. _Parotitis suppurans._ Mumps suppurative. ---- _mutabilis._ ---- mutable. ---- _felina._ ---- of cats. 5. _Catarrhus sensitivus._ Catarrh inflammatory. 6. ---- _contagiosus._ ---- contagious. ---- _equinus et caninus._ ---- among horses and dogs. 7. _Peripneumonia superficialis._ Superficial peripneumony. 8. _Pertussis._ Chin-cough. 9. _Variola discreta._ Small-pox distinct. ---- _confluens._ ---- confluent. ---- _inoculata._ ---- inoculated. 10. _Rubeola irritata._ Measles irritated. ---- _inirritata._ ---- inirritated. 11. _Scarlatina mitis._ Scarlet fever mild. ---- _maligna._ ---- malignant. 12. _Miliaria sudatoria._ Miliary fever sudatory. ---- _irritata._ ---- irritated. ---- _inirritata._ ---- inirritated. 13. _Pestis._ Plague. ---- _vaccina._ ---- of horned cattle. 14. _Pemphigus._ Bladdery fever. 15. _Varicella._ Chicken-pox. 16. _Urticaria._ Nettle rash. 17. _Aptha sensitiva._ Thrush sensitive. ---- _irritata._ ---- irritated. ---- _inirritata._ ---- inirritated. 18. _Dysenteria._ Bloody flux. 19. _Gastritis superficialis._ Superficial inflam. of the stomach. 20. _Enteritis superficialis._ ---- of the bowels. GENUS IV. _With the Production of new Vessels by internal Membranes or Glands, without Fever._ SPECIES. 1. _Ophthalmia superficialis._ Ophthalmy superficial. ---- _lymphatica._ ---- lymphatic. ---- _equina._ ---- of horses. 2. _Pterigion._ Eye-wing. 3. _Tarsitis palpebrarum._ Red eyelids. 4. _Hordeolum._ Stye. 5. _Paronychia superficialis._ Whitlow. 6. _Gutta rosea hepatica._ Pimpled face hepatic. ---- _stomatica._ ---- stomatic. ---- _hereditaria._ ---- hereditary. 7. _Odontitis._ Inflamed tooth. 8. _Otitis._ ---- ear. 9. _Fistula lacrymalis._ Fistula lacrymalis. 10. _Fistula in ano._ Fistula in ano. 11. _Fistula urethræ._ Fistula urethræ. 12. _Hepatitis chronica._ Chronical hepatitis. 13. _Scrophula suppurans._ Suppurating scrophula. 14. _Scorbutus suppurans._ Suppurating scurvy. 15. _Schirrus suppurans._ Suppurating schirrus. 16. _Carcinoma._ Cancer. 17. _Arthrocele._ Swelling of the joints. 18. _Arthropuosis._ Suppuration of the joints. 19. _Caries ossium._ Caries of the bones. GENUS V. _With the Production of new Vessels by external Membranes or Glands, without Fever._ SPECIES. 1. _Gonorrhoea venerea._ Clap. 2. _Syphilis._ Venereal disease. 3. _Lepra._ Leprosy. 4. _Elephantiasis._ Elephantiasis. 5. _Framboesia._ Framboesia. 6. _Psora._ Itch. 7. _Psora ebriorum._ Itch of drunkards. 8. _Herpes._ Herpes. 9. _Zona ignea._ Shingles. 10. _Annulus repens._ Ring-worm. 11. _Tinea capitis._ Scald-head. 12. _Crusta lactea._ Milk-crust. 13. _Trichoma._ Plica polonica. GENUS VI. _With Fever consequent to the Production of new Vessels or Fluids._ SPECIES. 1. _Febris sensitiva._ Sensitive fever. 2. ---- _a pure clauso._ Fever from concealed matter. 3. ---- _a vomica._ ---- from vomica. 4. ---- _ab empyemate._ ---- from empyema. 5. ---- _mesenterica._ ---- mesenteric. 6. ---- _a pure aerato._ ---- from aerated matter. 7. ---- _a phthisi._ ---- from consumption. 8. ---- _scrophulosa._ ---- scrophulous. 9. ---- _ischiadica._ ---- from ischias. 10. ---- _arthropuodica._ ---- from joint-evil. 11. ---- _a pure contagioso._ ---- from contagious matter. 12. ---- _variolosa secundaria._ ---- secondary of small-pox. 13. ---- _carcinomatosa._ ---- cancarous. 14. ---- _venerea._ ---- venereal. 15. ---- _a sanie contagiosa._ ---- from contagious sanies. 16. ---- _puerpera._ ---- puerperal. 17. ---- _a sphacelo._ ---- from sphacelus. GENUS VII. _With increased Action of the Organs of Sense._ SPECIES. 1. _Delirium febrile._ Delirium of fevers. 2. ---- _maniacale._ ---- maniacal. 3. ---- _ebrietatis._ ---- of drunkenness. 4. _Somnium._ Dreams. 5. _Hallucinatio visûs._ Deception of sight. 6. ---- _auditus._ ---- of hearing. 7. _Rubor a calore._ Blush from heat. 8. ---- _jucunditatis._ ---- from joy. 9. _Priapismus amatorius._ Amorous priapism. 10. _Distentio mamularum._ Distention of the nipples. ORDO II. _Decreased Sensation._ GENUS I. _With decreased Action of the general System._ SPECIES. 1. _Stultitia insensibilis._ Folly from insensibility. 2. _Tædium vitæ._ Irksomeness of life. 3. _Paresis sensitiva._ Sensitive debility. GENUS II. _With decreased Actions of particular Organs._ SPECIES. 1. _Anorexia._ Want of appetite. 2. _Adipsia._ Want of thirst. 3. _Impotentia._ Impotence. 4. _Sterilitas._ Barrenness. 5. _Insensibilitas artuum._ Insensibility of the limbs. 6. _Dysuria insensitiva._ Insensibility of the bladder. 7. _Accumulatio alvina._ Accumulation of feces. ORDO III. _Retrograde Sensitive Motions._ GENUS I. _Of Excretory Ducts._ SPECIES. _Motus retrogressus_ Retrograde motion. 1. ---- _ureterum._ ---- of the ureters. 2. ---- _urethræ._ ---- of the urethra. 3. ---- _ductus choledoci._ ---- of the bile-duct. * * * * * CLASS II. DISEASES OF SENSATION. ORDO I. _Increased Sensation._ GENUS I. _With Increased Action of the Muscles._ The actions belonging to this genus are those which are immediately excited by the sensations of pain or pleasure, but which are neither followed by inflammation, nor by convulsion. The former of which belong to the subsequent genera of this order, and the latter to the class of voluntary motions. The criterion between the actions, which are the immediate consequence of painful sensation, and convulsive actions properly so called, consists in the former having a tendency to dislodge the stimulating cause, which induces the painful sensation; and the latter being exerted for the purpose of expending the sensorial power, and thus dulling or destroying the general sensation of the system. See Class III. 1. There is a degree of heat produced in the affected part by these sensitive actions without inflammation, but in much less quantity than when attended by inflammation; as in the latter there is a production of new vessels. See Sect. XXXIII. 2. 3. Some of the species of this genus cannot properly be termed diseases in their natural state, but become so by their defect or excess, and are here inserted to facilitate the explanation of the others. SPECIES. 1. _Deglutitio._ Swallowing our food is immediately caused by the pleasureable sensation occasioned by its stimulus on the palate or fauces and is acquired long before the nativity of the animal. Afterwards the pain of hunger previously produces the various voluntary exertions to procure the proper material, but the actions of masticating and of swallowing it are effected by the sensorial power of sensation; which appears by their not being always controulable by the will, as when children in vain attempt to swallow nauseous drugs. See Class IV. 1. 3. 1. The masticated food stimulates the palate, which is an organ of sense, into so much action, as to produce agreeable sensation; and the muscles subservient to deglutition are brought into action by the sensation thus produced. The pleasureable sensation is the proximate cause; the action of the fibres of the extremities of the nerves of taste is the remote cause; the sensorial power of irritation exciting these fibres of the nerves of taste into increased action is the pre-remote cause; the action of the muscles of deglutition is the proximate effect; the pushing the food into the stomach is the remote effect; and the nutrition of the body is the post-remote effect. Though the muscles subservient to deglutition have their actions previously associated, so as to be excited into synchronous tribes or successive trains, either by volition, as when we swallow a disagreeable drug; or by sensation, as when we swallow agreeable food; or by irritation, as when we inattentively swallow our saliva; yet do all those three kinds of deglutition belong to the respective classes of volition, sensation, and irritation; because the first links of these tribes or trains of muscular action are excited by those sensorial powers, and the associated links, which accompany or succeed them, are excited by the combined powers either of volition, or of sensation, or of irritation, along with that of association. 2. _Respiratio._ Respiration is immediately caused by the sensorial power of sensation in consequence of the baneful want of vital air; and not from the accumulation of blood in the lungs, as that might be carried on by inhaling azote alone, without the oxygenous part of the atmosphere. The action of respiration is thus similar to that of swallowing our food to appease the pain of hunger; but the lungs being surrounded with air, their proper pabulum, no intermediate voluntary exertions are required, as in hunger, to obtain and prepare the wanted material. Respiration is similar to slow combustion; the oxygenous part of the atmosphere is received through the moist membranes, which line the air-cells of the lungs, and uniting with the inflammable part of the blood generates an acid, probably the phosphoric acid; a portion of carbonic acid is likewise produced in this process; as appears by repeatedly breathing over lime-water, which then becomes turbid. See Botanic Garden, P. I. Canto I. l. 401. note. 3. _Sternutatio._ Sneezing consists of muscular actions produced by the sensorial faculty of sensation; and is an effort to dislodge, by means of air forcibly impelled through the nostrils, some material; which stimulates the membrane, which lines them, into too great action, and might thence injure the sense of smell which is diffused on it. In this operation the too great action of the vessels of the membrane of the nostrils is the remote cause; the sensation thence induced is the proximate cause; and the muscular actions are the proximate effect. This action of sneezing frequently precedes common respiration in new-born children, but I believe not always; as like the latter it cannot have been previously acquired in the uterus. It is produced in some people by sudden light, as by looking up at the sky in a morning, when they come out of a gloomy bed-chamber. It then becomes an associate action, and belongs to Class IV. 1. 2. 2. M. M. When it is exerted to excess it may be cured by snuffing starch up the nostrils. See Class I. 1. 2. 13. 4. _Anhelitus._ Panting. The quick and laborious breathing of running people, who are not accustomed to violent exercise, is occasioned by the too great conflux of blood to the lungs. As the sanguiferous system, as well as the absorbent system, is furnished in many parts of its course with valves, which in general prevent the retrograde movement of their contained fluids; and as all these vessels, in some part of their course, lie in contact with the muscles, which are brought into action in running, it follows that the blood must be accelerated by the intermitted swelling of the bellies of the muscles moving over them. The difficulty of breathing, with which, very fat people are immediately affected on exercise, is owing to the pressure of the accumulated fat on the veins, arteries, and lymphatics; and which, by distending the skin, occasions it to act as a tight bandage on the whole surface of the body. Hence when the muscles are excited into quicker action, the progress of the blood in the veins, and of the lymph and chyle in the absorbent system, is urged on with much greater force, as under an artificial bandage on a limb, explained in Art. IV. 2. 10. and in Sect. XXXIII. 3. 2. Hence the circulation is instantly quickened to a great degree, and the difficulty of breathing is the consequence of a more rapid circulation through the lungs. The increased secretion of the perspirable matter is another consequence of this rapid circulation; fat people, when at rest, are believed to perspire less than others, which may be gathered from their generally having more liquid stools, more and paler urine, and to their frequently taking less food than many thin people; and lastly, from the perspiration of fat people being generally more inodorous than that of lean ones; but when corpulent people are put in motion, the sweat stands in drops on their skins, and they "lard the ground" as they run. The increase of heat of corpulent people on exercise, is another consequence of their more rapid circulation, and greater secretion. See Class I. 2. 3. 17. Other causes of difficult or quick respiration will be treated of under Asthma, Pertussis, Peripneumony, Tonsillitis. 5. _Tussis ebriorum._ Sensitive cough is an exertion of the muscles used in expiration excited into more violent action by the sensorial power of sensation, in consequence of something which too powerfully stimulates the lungs. As the saline part of the secreted mucus, when the absorption of it is impeded; or the too great viscidity of it, when the absorption is increased; or the too great quantity of the mucus, when the secretion is increased; or the inflammation of the membranes of the lungs; it is an effort to dislodge any of these extraneous materials. Of this kind is the cough which attends free-drinkers after a debauch; it consists of many short efforts to cough, with a frequent expuition of half a tea-spoonful of frothy mucus, and is attended with considerable thirst. The thirst is occasioned by the previous dissipation of the aqueous parts of the blood by sensible or insensible perspiration; which was produced by the increased action of the cutaneous and pulmonary capillaries during the stimulus of the wine. In consequence of this an increased absorption commences to replace this moisture, and the skin and mouth become dry, and the pulmonary mucus becomes inspissated; which stimulates the bronchia, and is raised into froth by the successive currents of air in evacuating it. This production of froth is called by some free-drinkers "spitting sixpences" after a debauch. This subsequent thirst, dry mouth, and viscid expectoration in some people succeeds the slightest degree of intoxication, of which it may be esteemed a criterion. See Class IV. 2. 1. 8. As coughs are not always attended with pain, the muscular actions, which produce them, are sometimes excited by the sensorial faculty of irritation, as in Class I. 1. 2. 8. I. 1. 3. 4. I. 1. 4. 3. I. 2. 3. 4. Coughs are also sometimes convulsive, as in Class III. 1. 1. 10. and sometimes sympathetic, as Class IV. 2. 1. 7. M. M. Venesection, when the cough is attended with inflammation. Mucilages. Opium. Torpentia. Blister. 6. _Singultus._ Hiccough is an exertion of the muscles used in inspiration excited into more violent action by the sensorial power of sensation, in consequence of something which too powerfully stimulates the cardia ventriculi, or upper orifice of the stomach. As when solid food is too hastily taken without sufficient dilution. And is an effort to dislodge that offensive material, and push it to some less sensible part of the stomach, or into the middle of the contained aliment. At the end of fatal fevers it may arise from the acrimony of the undigested aliment, or from a part of the stomach being already dead, and by its weight or coldness affecting the surviving part with disagreeable sensation. The pain about the upper orifice of the stomach is the proximate cause, the too great or too little action of the fibres of this part of the stomach is the remote cause, the action of the muscles used in inspiration is the proximate effect, and the repercussion of the offending material is the remote effect. Hiccough is sometimes sympathetic, occasioned by the pain of gravel in the kidney or ureter, as in Class IV. 1. 1. 7. and is sometimes a symptom of epilepsy or reverie, as in Sect. XIX. 2. M. M. Oil of cinnamon from one drop gradually increased to ten, on sugar, or on chalk. Opium. Blister. Emetic. 7. _Asthma humorale._ The humoral asthma probably consists in a temporary anasarca of the lungs, which may be owing to a temporary defect of lymphatic absorption. Its cause is nevertheless at present very obscure, since a temporary deficiency of venous absorption, at the extremities of the pulmonary or bronchial veins, might occasion a similar difficulty of respiration. See Abortio, Class I. 2. 1. 14. Or it might be supposed, that the lymph effused into the cavity of the chest might, by some additional heat during sleep, acquire an aerial form, and thus compress the lungs; and on this circumstance the relief, which these patients receive from cold air, would be readily accounted for. The paroxysms attack the patient in his first sleep, when the circulation through the lungs in weak people wants the assistance of the voluntary power. Class I. 2. 1. 3. And hence the absorbents of the lungs are less able to fulfil the whole of their duty. And part of the thin mucus, which is secreted into the air-cells, remains there unabsorbed, and occasions the difficult respiration, which awakes the patient. And the violent exertions of the muscles of respiration, which succeed, are excited by the pain of suffocation, for the purpose of pushing forwards the blood through the compressed capillaries, and to promote the absorption of the effused lymph. In this the humoral differs from the convulsive asthma, treated of in Class III. 1. 1. 10. as in that there is probably no accumulated fluid to be absorbed; and the violent respiration is only an exertion for the purpose of relieving pain, either in the lungs or in some distant part, as in other convulsions, or epilepsy; and in this respect the fits of humoral and convulsive asthma essentially differ from each other, contrary to the opinion expressed without sufficient consideration in Sect. XVIII. 15. The patients in the paroxysms both of humoral and convulsive asthma find relief from cold air, as they generally rise out of bed, and open the window, and put out their heads; for the lungs are not sensible to cold, and the sense of suffocation is somewhat relieved by there being more oxygen contained in a given quantity of cold fresh air, than in the warm confined air of a close bed-chamber. I have seen humoral asthma terminate in confirmed anasarca, and destroy the patient, who had been an excessive drinker of spirituous potation. And M. Savage asserts, that this disease frequently terminates in diabetes; which seems to shew, that it is a temporary dropsy relieved by a great flow of urine. Add to this, that these paroxysms of the asthma are themselves relieved by profuse sweats of the upper parts of the body, as explained in Class I. 3. 2. 8. which would countenance the idea of their being occasioned by congestions of lymph in the lungs. The congestion of lymph in the lungs from the defective absorption of it is probably the remote cause of humoral asthma; but the pain of suffocation is the immediate cause of the violent exertions in the paroxysms. And whether this congestion of lymph in the air-cells of the lungs increases during our sleep, as above suggested, or not; the pain of suffocation will be more and more distressing after some hours of sleep, as the sensibility to internal stimuli increases during that time, as described in Sect. XVIII. 15. For the same reason many epileptic fits, and paroxysms of the gout, occur during sleep. In two gouty cases, complicated with jaundice, and pain, and sickness, the patients had each of them a shivering fit, like the commencement of an ague, to the great alarm of their friends; both which commenced in the night, I suppose during their sleep; and the consequence was a cessation of the jaundice, and pain about the stomach, and sickness; and instead of that the gout appeared in their extremities. In these cases I conjecture, that there was a metastasis not only of the diseased action from the membranes of the liver to those of the foot; but that some of the new vessels, or new fluids, which were previously produced in the inflamed liver, were translated to the feet during the cold fit, by the increased absorption of the hepatic lymphatics, and by the retrograde motions of those of the affected limbs. This I think resembles in some respects a fit of humoral asthma, where stronger motions of the absorbent vessels of the lungs are excited, and retrograde ones of the correspondent cutaneous lymphatics; whence the violent sweats of the upper parts of the body only are produced; and for a time the patient becomes relieved by the metastasis and elimination of the offending material by sensitive exertion. For a further account of this intricate subject see Class III. 1. 1. 10. M. M. To relieve the paroxysm a tea-spoonful of ether may be given mixed with water, with 10 drops of laudanum, to be repeated three or four times. Venesection. An emetic. A blister. Afterwards the Peruvian bark, with a grain of opium at night, and two or three of aloes. A flannel shirt in winter, but not in summer. Issues. Digitalis? In this species of asthma, there is great reason to believe, that the respiration of an atmosphere, with an increased proportion of oxygen, will prove of great advantage; some well-observed and well-attested cases of which are published by Dr. Beddoes; as this purer air invigorates the circulation, and the whole system in consequence, perhaps not only by its stimulus, but by its supplying the material from which the sensorial power is extracted or fabricated. In spasmodic asthma, on the contrary, Dr. Ferriar has found undoubted benefit from an atmosphere mixed with hydrogen. See Sect. XVIII. 15. and Class III. 1. 1. 10. 8. _Nictitatio sensitiva._ Winking of the eyes is performed every minute, without our attention, for the purpose of diffusing the tears over them, which are poured into the eye a little above the external corner of it, and which are afterwards absorbed by the lacrymal points above and below the internal corner of it. When this operation is performed without our attention, it is caused by the faculty of irritation, and belongs to Class I. 1. 4. 1. but when it is produced by a stronger stimulus of any extraneous material in the eye, so as to cause pain, the violent and frequent nictitation is caused by the faculty of sensation. This disease is sometimes produced by the introversion of the edge of the lower eyelid, which bends the points of the hairs of the eyelash upon the ball of the eye, which perpetually stimulate it into painful sensation. This introversion of the eyelid is generally owing to a tumor of the cellular membrane below the edge of the eyelid, and though a very troublesome complaint may often be cured by the following simple means. A little common plaster spread on thin linen, about a quarter of an inch long, must be rolled up so as to be about the size of a crow-quill, this must be applied immediately below the eyelash on the outside of the eye; and must be kept on by another plaster over it. This will then act as a slight compression on the tumor under the eyelash, and will prevent the hairs from touching the eye-ball. In a week or two the compression will diminish the tumor it lies over, and cure this painful deformity. 9. _Oscitatio et pandiculatio._ Yawning and stretching of the limbs is produced either by a long inactivity of the muscles now brought into action, as sometimes happens after sleep, or after listening a long time to a dull narrative; or it is produced by a too long continued action of the antagonist muscles. In the former case there is an accumulation of sensorial power during the quiescence of the muscles now brought into action; which probably constitutes the pain or wearisomeness of a continued attitude. In the latter case there is an exhaustion of sensorial power in the muscles, which have lately been acting violently, and a consequent accumulation in the muscles, which are antagonists to them, and which were at rest. These involuntary motions are often seen in paralytic limbs, which are at the same time completely disobedient to the will; and are frequently observable in very young children; and from thence we may conclude, that these motions are learnt before nativity; as puppies are seen to open their mouths before the membranes are broken. See Sect. XVI. 2. Where these motions are observed in limbs otherwise paralytic, it is an indication that electric shocks may be employed with advantage, as the excitability of the limb by irritation is not extinct, though it be disobedient both to volition and sensation. 10. _Tenesmus_ consists in violent and frequent ineffectual efforts to discharge the contents of the rectum, owing to pain of the sphincter. The pain is produced by indurated feces, or by some acrid material, as the acidity of indigested aliment; and the efforts are attended with mucus from the pained membrane. The feces must sometimes be taken away by the end of a marrow-spoon, as cathartics and even clyster will pass without removing them. It is sometimes caused by sympathy with the urethra, when there is a stone at the neck of the bladder. See Class II. 2. 2. 7. and IV. 1. 2. 8. M. M. Fomentation, an enema with mucilage and laudanum. The common exclusion of the feces from the rectum is a process similar to this, except that the muscles of the sphincter ani, and those of the abdomen, which act along with them by the combined powers of sensation and association, are in tenesmus excited by painful sensation, and in the latter by a sensation, which may in some instances be almost called pleasurable, as relieving us from a painful one in the exclusion of the feces. 11. _Stranguria._ Strangury consists in painful efforts to discharge the contents of the urinary bladder. It is generally owing to a stone in the sphincter of the bladder; or to the inflammation of the neck of it occasioned by cantharides. It is sometimes caused by sympathy with the piles; and then is liable in women to occasion convulsions, from the violence of the pain without inflammation. See Class IV. 2. 2. 2. and 3. M. M. Fomentation clyster with oil and laudanum, push the stone back with a bougie; if from cantharides give half a pint of warm water every ten minutes. Mucilage of gum arabic and tragacanth. The natural evacuation of the urine is a process similar to this, except that the muscular fibres of the bladder, and the muscles of the abdomen, which act in concert with them by the combined powers of sensation and of association, are, in the former case of strangury, excited into action by painful sensation; and in the latter by a sensation, which may almost be termed pleasurable, as it relieves us from a previous uneasy one. The ejectio feminis is another process in some respects similar to strangury, as belonging to the same sensible canal of the urethra, and by exciting into action the accelerator muscles; but in the strangury these muscles are excited into action by painful sensation, and in the ejection of the semen by pleasureable sensation. 12. _Parturitio._ Parturition is not a disease, it is a natural process, but is more frequently unfortunate in high life than amongst the middle class of females; which may be owing partly to fear, with which the priests of LUCINA are liable to inspire the ladies of fashion to induce them to lie in in town; and partly to the bad air of London, to which they purposely resort. There are however other causes, which render parturition more dangerous to the ladies of high life; such as their greater general debility from neglect of energetic exercise, their inexperience of the variations of cold and heat, and their seclusion from fresh air. To which must be added, that great source of the destruction of female grace and beauty, as well as of female health, the tight stays, and other bandages, with which they are generally tortured in their early years by the active folly of their friends, which by displacing many of the viscera impedes their actions, and by compressing them together produces adhesions of one part to another, and affects even the form and aperture of the bones of the pelvis, through which the nascent child must be protruded. As parturition is a natural, not a morbid process, no medicine should be given, where there is no appearance of disease. The absurd custom of giving a powerful opiate without indication to all women, as soon as they are delivered, is, I make no doubt, frequently attended with injurious, and sometimes with fatal consequences. See Class II. 1. 2. 16. Another thing very injurious to the child, is the tying and cutting the navel-string too soon; which should always be left till the child has not only repeatedly breathed, but till all pulsation in the cord ceases. As otherwise the child is much weaker than it ought to be; a part of the blood being left in the placenta, which ought to have been in the child; and at the same time the placenta does not so naturally collapse, and withdraw itself from the sides of the uterus, and is not therefore removed with so much safety and certainty. The folly of giving rue or rhubarb to new-born children, and the danger of feeding them with gruel instead of milk, is spoken of in Class I. 1. 2. 5. and II. 1. 2. 16. * * * * * ORDO I. _Increased Sensation._ GENUS II. _With the Production of new Vessels by internal Membranes or Glands, with Fever._ In the first class of diseases two kinds of fevers were described, one from excess, and the other from defect of irritation; and were in consequence termed irritative, and inirritative fevers. In this second class of diseases another kind of fever occurs, which is caused by excess of sensation, and termed in consequence Sensitive Fever. But there is no fever from defect of sensation, because the circulation is carried on in health without our consciousness, that is, without any sensation attending it. But as excess of sensation may exist with excess or defect of irritation, two other kinds of fever arise from a combination of sensitive fever with the irritative, and inirritative ones. Making five kinds in all. 1. Irritative fever, described in Class I. 1. 1. 1. 2. Inirritative fever. Class I. 2. 1. 1. 3. Sensitive fever. Class II. 1. 6. 1. 4. Sensitive irritated fever. Class II. 1. 2. 1. 5. Sensitive inirritated fever. Class II. 1. 3. 1. As the sensitive irritated fever attends all the diseases enumerated under the genus about to be described, it is placed at the head of it. And as the sensitive inirritated fever accompanies the greatest number of the species enumerated under the third genus of this order, it is placed at the head of them. And as the sensitive fever attends the diseases of the sixth genus, it is placed at the head of them. But as every febrile paroxysm consists of disordered tribes or trains of associated motions, it may be doubted, whether they ought not all to have been placed in the fourth class, amongst the diseases of association. See Class IV. 2. 4. 11. All the subsequent species of this genus are attended with sensitive irritated fever; there are nevertheless some superficial inflammations, which affect the same situations without much fever, as the scrophulous ophthalmy and spurious peripneumony, which belong to other genera. Inflammation is uniformly attended with the production or secretion of new fibres constituting new vessels; this therefore may be esteemed its essential character, or the criterion of its existence. The extension of the old vessels seems rather a consequence than a cause of the germination, or pullulation, of these new ones; for the old vessels may be enlarged, and excited with unusual energy, without any production of new ones, as in the blush of shame or of anger. When these new vessels are formed, if they are not reabsorbed into the circulation, they secrete a new fluid called purulent matter; which generally opens itself a passage on the external skin, and produces an ulcer, which either gradually heals, or spreads, and is the cause of hectic fever; or they secrete contagious matter, which has the property of exciting the same kind of inflammation, and of producing the same kind of contagious matter, when inserted by inoculation into the skin of other persons. These contagious matters form ulcers, which either heal spontaneously, or by art; or continue to spread, and destroy the patient, by other kinds of hectic fever. In this genus there is an increase of the sensorial power of irritation as well as of sensation; whence great arterial energy is produced, and the pulse becomes strong and full, as well as quick; and the coats of the arteries feel hard under the finger, being themselves thickened and distended by inflammation. The blood drawn, especially at the second bleeding, is covered with a tough size; which is probably the mucus from the inflamed internal surface of the arteries, increased in quantity, and more coagulable than in its natural state; the thinner part being more perfectly absorbed by the increased action of the inflamed absorbents. See Sect. XXXIII. 2. 2. This is rendered more probable, because the hard feel of the pulse, and the abundance of coagulable lymph commence, exist, and cease together. Great heat is produced from the new chemical combinations arising in the secretion of new fibres, and great pain from the distention of old ones, or from their increased action. The increased quantity of sensation from a topical inflammation or phlegmon is the immediate cause of the febris sensitiva irritata, or inflammatory fever; as when it arises from the pain of pleurisy, or paronychia; but generally an irritative fever precedes this topical inflammation, which occurs during the hot fit of it; and then the irritative fever is changed into a sensitive irritated fever, by the additional cause of the sensorial power of sensation besides that of irritation. SPECIES. 1. _Febris sensitiva irritata._ Sensitive irritated fever, or inflammatory fever. Phlegmasia. A strong full pulse, with inflammation of the coats of the arteries, constitutes this disease. It originates from some topical inflammation, which, if the fever is not subdued, terminates in suppuration; and differs from irritative fever in respect to the painful sensation which accompanies it. For as pleasurable sensation is the cause of the growth of the new vessels, and distention of the old ones, in the natural enlargement of the body during our infancy; so a painful sensation is the cause of the unnatural production of new vessels, and enlargement of old ones in inflammatory diseases. When matter is thus formed in any internal viscus, or in the cellular membrane, as in the lungs or liver; so long as this abscess remains without admission of air, this inflammatory fever is liable to continue, receiving only temporary relief by bleeding or emetics, or cathartics; till the patient, after a month, or two, or three, expires. But, if air be admitted to these internal abscesses, this kind of fever is changed into a hectic fever in a single day. It also sometimes happens, that when the abscess remains unopened to the air, if the matter has become putrid, that hectic fever supervenes, with colliquative sweats, or diarrhoea; the matter in both cases is sometimes absorbed, and the sides of the abscess grow together again without an external aperture. See Class II. 1. 4. 1. and 2. Another termination of inflammation is in gangrene, but this belongs to the inflammation of the external skin; as the production of purulent matter belongs to inflammation of the internal or mucous membranes. Thus when the external skin is the seat of inflammation, as in erythema, or erysipelas, and produces sensitive irritated fever, no collection of purulent matter can be formed; but a material oozes out, and lies upon the surface, like that in the confluent small-pox, and the cuticle at length peels off, or gangrene supervenes. It must be noted, that these kinds of inflammation can exist together; and some parts of the cellular membrane may suppurate at the same time that the external skin is affected with erythema, or erysipelas. M. M. Venesection. Cathartics. Diluents. Cool air. Torpentia. Cold Bath? See Sect. XII. 6. The increased arterial action in this sensitive irritated fever is not simply owing to the increased irritability of the arterial system, or to the stimulus of the distention of the vessels, but also to the increased acrimony or pungency of the blood; which has now so far changed its nature as to become more fluid, more dense, and to be loaded with coagulable lymph. Hence it becomes necessary not only to lessen the quantity of blood by venesection and by cathartics, but also to dilute its acrimony, or pungency, by the introduction of aqueous and mucilaginous fluids, such as barley water, cream and water, sugar and water, weak broths; to which may be added so much of some vegetable essential oil, as may render them grateful to the stomach, and thus promote their absorption, as by infusing parsley or cellery and turneps in the broth; or by balm, mint, or sage teas. The following species of this genus only distinguish the situation of the part previously inflamed, and which is the remote cause of the sensitive irritated, or inflammatory fever, which attends it. 2. _Ophthalmia interna._ Inflammation of the eye is attended with the production of new vessels, which spread over the tunica adjunctiva, and over the cornea; these new vessels are easily seen, as they lie on a white ground, and give ocular demonstration of their production in inflammation. When this inflammation of the cornea suppurates, it is liable to leave little ulcers, which may be seen beneath the surface in the form of little excavations; and as these heal, they are liable to be covered with an opake scar. This scar, in some months or years, is liable to wear away, and become transparent, without the assistance of any polishing powder, as of very finely levigated glass, as some have recommended. But when the cornea is affected through all its thickness, the return of its transparency becomes hopeless. See Class I. 1. 3. 14. In violent degrees of ophthalmy the internal parts, as the retina, optic artery, iris, ciliary process, become inflamed, as well as the external ones; hence the least light admitted to the eye occasions intolerable pain. This curious circumstance cannot be owing to the action of light on the inflamed vessels of the cornea; it therefore shews, that the extremity of the optic nerve or retina is also rendered more exquisitely sensible to light, by partaking of the inflammation; and I have been told, that red colours are in these cases sometimes painfully perceived even in perfect darkness. This shews that the retina is excited into motion by the stimulus of light; and that, when it is inflamed, these motions give great pain, like those of other inflamed parts, as the muscles, or membranes. And secondly, that the ideas of colours consist in the motions of the retina; which ideas occasion pain, when the extremity of the moving nerve is inflamed. M. M. Venesection. Cathartics. Diluents. Torpentia. Frequently moisten the eye with cold water by means of a rag. Cool airy room. Darkness. When the inflammation begins to decline, white vitriol gr. vi. in an ounce of water is more efficacious to moisten the eye than solutions of lead. Tincture of opium diluted. New vessels from the inflamed tunica adnata frequently spread like a fly's wing upon the transparent cornea, which is then called Pterigium. To stop the growth of this, the principal vessels should be cut through with a lancet. When the inflammation begins to decline, after due evacuation any stimulating material put into the eye increases the absorption, which soon removes the new red vessels; which has given rise to a hundred famous eye-waters, and eye-doctors; if these stimulating materials are used too soon, the inflammation is increased by them. See Sect. XXXII. 2. 10. There is another ophthalmia, which attends weak children, and is generally esteemed a symptom of scrophula, as described in Class II. 1. 4. 1. and another, which is of venereal origin, mentioned in Class II. 1. 5. 2. both which may be termed ophthalmia superficialis. 3. _Phrenitis._ Inflammation of the brain is attended with intolerance of light and sound; which shews, that the extremities of the nerves of those senses are at the same time inflamed; it is also attended with great pain of the head, with watchfulness, and furious delirium. The violent efforts, these patients are said sometimes to exert, are owing to the increased secretion of sensorial power in the brain; as all other inflamed glands have a greater circulation of blood passing through them, and a greater secretion in consequence of their peculiar fluids, as in the hepatitis much more bile is generated. M. M. Venesection. Cathartics. Torpentia. Foment the head with cold water for hours together. Or with warm water. Cool airy room. Afterwards cupping on the occiput. Leeches to the temples. When the patient is weakened a blister on the head, and after further exhaustion five or six drops of tincture of opium. 4. _Peripneumonia._ Inflammation of the lungs. The pulse is not always hard, sometimes soft; which is probably owing to a degree of sickness or inaction of the stomach; with dull pain of the chest; respiration constantly difficult, sometimes with erect posture; the face bloated and purplish; cough generally with moist expectoration, often stained with blood. When the difficulty of respiration is very great, the patient is not able to cough; in this situation, after copious bleeding, the cough is liable to return, and is so far a favourable symptom, as it shews some abatement of the inflammation. A peripneumony frequently occurs in the chin-cough, and destroys the patient, except immediate recourse be had to the lancet, or to four or five leeches; when blood cannot be otherwise taken. The peripneumony is very fatal to young children, especially as I believe it is frequently mistaken for a spasmodic asthma, or for the croup, or cynanche trachealis of Cullen. Both which, however, when they occur, require immediate venesection by the lancet or by leeches, as well as the peripneumony. The croup is an inflammation of the upper part, and the peripneumony of the lower part of the same organ, viz. the trachea or windpipe. See Class I. 1. 3. 4. But as the inflammation is seldom I suppose confined to the upper part of the trachea only, but exists at the same time in other parts of the lungs, and as no inflammation of the tonsils is generally perceptible, the uncouth name of cynanche trachealis should be changed for _peripneumonia trachialis_. The method of cure consists in immediate and repeated bleeding. A vomit. A grain of calomel or other mild cathartic. Bathing in subtepid water, and in breathing over the steam of warm water, with or without a little vinegar in it. And lastly, by keeping the child raised high in bed. Inflammation of the lungs is also liable to occur in the measles, and must be attacked by venesection at any time of the disease; otherwise either a present death, or an incurable consumption, is the consequence. The peripneumony is frequently combined with inflammation of the pleura, and sometimes with that of the diaphragm; either of these may generally be distinguished, not only by the pain which attends inflammation of these membranes, but by inspecting the naked chest, and observing whether the patient breathes more by elevating the ribs, or by depressing the diaphragm. A crisis happens in children about the sixth day with much pale urine, which must be waited for after evacuations have been used, as far as can be done with safety; in this situation the warm bath twice a day, and small blisters repeatedly in succession, are of peculiar service. After the termination of peripneumony a collection of coagulable lymph is frequently left in the cavity of the chest unabsorbed; or a common anasarca of the lungs occurs from the present inaction of the absorbent vessels, which had previously been excited too violently. This difficulty of breathing is cured or relieved by the exhibition of digitalis. See Art. IV. 2. 8. M. M. The lancet is the anchor of hope in this disease; which must be repeated four or five times, or as often as the fever and difficulty of breathing increase, which is generally in the evening; antimonials, diluents, repeated small blisters about the chest, mucilage, pediluvium, warm bath. Is a decoction of seneka-root of use? Do not neutral salts increase the tendency to cough by their stimulus, as they increase the heat of urine in gonorrhoea? Children in every kind of difficult breathing, from whatever cause, should be kept as upright in bed as may be, and continually watched; since, if they slip down, they are liable to be immediately suffocated. After the patient is greatly debilitated, so that no further evacuation can be admitted, and the difficult breathing and cough continue, I have given four or five drops of tincture of opium, that is, about a quarter of a grain of solid opium, with great advantage, and I believe in several cases I have saved the patient. A greater quantity of opium in this state of debility cannot be used without hazarding the life of the person. This small quantity of an opiate should be given about six in the evening, or before the access of the evening paroxysm, and repeated three or four nights, or longer. There is a peripneumony with weak pulse, which may be termed _peripneumonia inirritata_, as described in Sect. XXVII. 2. which belongs to this place. See also Superficial Peripneumony, Class II. 1. 3. 7. 5. _Pleuritis._ Pleurisy. Inflammation of the pleura, with hard pulse, pain chiefly of the side, pungent, particularly increased during inspiration; lying on either side uneasy, the cough very painful, dry at the beginning, afterwards moist, often bloody. One cause of pleurisy is probably a previous adhesion of the lungs to a part of the pleura, which envelops them. This in many cases has been produced in infancy, by suffering children to lie too long on one side. Or by placing them uniformly on one side of a fire, or window, to which they will be liable always to bend themselves. When matter is produced during peripneumony or pleurisy in one side of the chest, so long as it is a concealed vomica, the fever continues, if the disease be great, for many weeks, and even months; and requires occasional venesection, till the patient sinks under the inflammatory or sensitive irritated fever. But if air be admitted, by a part of the abscess opening itself a way into the air-vessels of the lungs, a hectic fever, with colliquitive sweats or diarrhoea, supervenes, and frequently destroys the patient; or the abscess heals the lungs adhering to the pleura. M. M. The lancet must be used copiously, and repeated as often as the pain and difficult respiration increase. A blister on the pained part. Antimonial preparations. Diluents. Cool air. Do neutral salts increase the tendency to cough? Pediluvium or semicupium frequently repeated. 6. _Diaphragmitis._ Inflammation of the diaphragm. Pain round the lower ribs as if girt with a cord. Difficult respiration performed only by elevating the ribs and in an erect posture. The corners of the mouth frequently retracted into a disagreeable smile, called risus Sardonicus. Those animals, which are furnished with clavicles, or collar-bones, not only use their foremost feet as hands, as men, monkies, cats, mice, squirrels, &c. but elevate their ribs in respiration as well as depress the diaphragm for the purpose of enlarging the cavity of the chest. Hence an inflammation of the diaphragm is sudden death to those animals, as horses and dogs, which can only breaths by depressing the diaphragm; and is I suppose the cause of the sudden death of horses that are over-worked; whereas, in the human animal, when the diaphragm is inflamed, so as to render its motions impossible from the pain they occasion, respiration can be carried on, though in a less perfect manner, by the intercostal muscles in the elevation of the ribs. In pleurisy the ribs are kept motionless, and the respiration is performed by the diaphragm, as may be readily seen on inspecting the naked chest, and which is generally a bad symptom; in the diaphragmitis the ribs are alternately elevated, and depressed, but the lower part of the belly is not seen to move. M. M. As in pleurisy and peripneumony. When the patient becomes delirious, and smiles disagreeably by intervals, and is become so weak, that evacuations by the lancet could be used no further, and I have almost despaired of my patient, I have found in two or three instances, that about five or six drops of tinct. thebaic, given an hour before the evening exacerbation, has had the happiest effect, and cured the patient in this case, as well as in common peripneumony; it must be repeated two or three evenings, see Class II. 1. 2. 4. as the exacerbation of the fever and difficult respiration and delirium generally increase towards night. The stimulus of this small quantity of opium on a patient previously so much debilitated, acts by increasing the exertion of the absorbent vessels, in the same manner as a solution of opium, or any other stimulant, put on an inflamed eye after the vessels are previously emptied by evacuations, stimulates the absorbent system, so as to cause the remaining new vessels to be immediately reabsorbed. Which same stimulants would have increased the inflammation, if they had been applied before the evacuations. See Class II. 1. 2. 2. Sect. XXXIII. 3. 1. When the sanguiferous system is full of blood, the absorbents cannot act so powerfully, as the progress of their contents is opposed by the previous fulness of the blood-vessels; whence stimulants in that case increase the action of the secerning system more than of the absorbent one; but after copious evacuation this resistance to the progress of the absorbed fluids is removed; and when stimulants are then applied, they increase the action of the absorbent system more than that of the secerning one. Hence opium given in the commencement of inflammatory diseases destroys the patient; and cures them, if given in very small doses at the end of inflammatory diseases. 7. _Carditis._ Inflammation of the heart is attended with unequal intermitting pulse, palpitation, pain in the middle of the sternum, and constant vomiting. It cannot certainly be distinguished from peripneumony, and is perhaps always combined with it. 8. _Peritonitis._ Inflammation of the peritonæum is known by pain all over the abdomen, which is increased on erecting the body. It has probably most frequently a rheumatic origin. See Class II. 1. 2. 17. 9. _Mesenteritis._ Inflammation of the mesentery is attended with pains like colic, and with curdled or chyle-like stools. It is a very frequent and dangerous disease, as the production of matter more readily takes place in it than in any other viscus. The consequence of which, after a hard labour, is probably the puerperal fever, and in scrophulous habits a fatal purulent fever, or hopeless consumption. M. M. Venesection. Warm bath. Emollient clysters. 10. _Gastritis._ In inflammation of the stomach the pulse is generally soft, probably occasioned by the sickness which attends it. The pain and heat of the stomach is increased by whatever is swallowed, with immediate rejection of it. Hiccough. This disease may be occasioned by acrid or indigestible matters taken into the stomach, which may chemically or mechanically injure its interior coat. There is however a slighter species of inflammation of this viscus, and perhaps of all others, which is unattended by much fever; and which is sometimes induced by drinking cold water, or eating cold insipid food, as raw turnips, when the person has been much heated and fatigued by exercise. For when the sensorial power has been diminished by great exertion, and the stomach has become less irritable by having been previously stimulated by much heat, it sooner becomes quiescent by the application of cold. In consequence of this slight inflammation of the stomach an eruption of the face frequently ensues by the sensitive association of this viscus with the skin, which is called a surfeit. See Class IV. 1. 2. 13. and II. 1. 4. 6. and II. 1. 3. 19. M. M. Venesection. Warm bath. Blister. Anodyne clysters. Almond soap. See Class II. 1. 3. 17. 11. _Enteritis._ Inflammation of the bowels is often attended with soft pulse, probably owing to the concomitant sickness; which prevents sometimes the early use of the lancet, to the destruction of the patient. At other times it is attended with strong and full pulse like other inflammations of internal membranes. Can the seat of the disease being higher or lower in the intestinal canal, that is, above or below the valve of the colon, produce this difference of pulse by the greater sympathy of one part of the bowels with the stomach than another? In enteritis with strong pulse the pain is great about the navel, with vomiting, and the greatest difficulty in procuring a stool. In the other, the pain and fever is less, without vomiting, and with diarrhoea. Whence it appears, that the enteritis with hard quick pulse differs from Ileus, described in Class I. 3. 1. 6. only in the existence of fever in the former and not the latter, the other symptoms generally corresponding; and, secondly, that the enteritis with softer quick pulse, differs from the cholera described in Class I. 3. 1. 5. only in the existence of fever in the former, and not the latter, the other symptoms being in general similar. See Class II. 1. 3. 20. Inflammation of the bowels sometimes is owing to extraneous indigestible substances, as plum-stones, especially of the damasin, which has sharp ends. Sometimes to an introsusception of one part of the intestine into another, and very frequently to a strangulated hernia or rupture. In respect to the first, I knew an instance where a damasin stone, after a long period of time, found its way out of the body near the groin. I knew another child, who vomited some damasin stones, which had lain for near twenty hours, and given great pain about the navel, by the exhibition of an emetic given in repeated doses for about an hour. The swallowing of plum-stones in large quantities, and even of cherry-stones, is annually fatal to many children. In respect to the introsusception and hernia, see Ileus, Class I. 3. 1. 6. M. M. Repeated venesection. Calomel from ten to twenty grains given in small pills as in Ileus; these means used early in the disease generally succeed. After these evacuations a blister contributes to stop the vomiting. Warm bath. Crude mercury. Aloes one grain-pill every hour will frequently stay in the stomach. Glauber's salt dissolved in pepper-mint water given by repeated spoonfuls. When the patient is much reduced, opium in very small doses may be given, as a quarter of a grain, as recommended in pleurisy. If the pain suddenly ceases, and the patient continues to vomit up whatever is given him, it is generally fatal; as it indicates, that a mortification of the bowel is already formed. Some authors have advised to join cathartic medicines with an opiate in inflammation of the bowels, as recommended in colica saturnina. This may succeed in slighter cases, but is a dangerous practice in general; since, if the obstruction be not removed by the evacuation, the stimulus of the opium is liable to increase the action of the vessels, and produce mortification of the bowel, as I think I have seen more than once. 12. _Hepatitis._ Inflammation of the liver is attended with strong quick pulse; tension and pain of the right side; often pungent as in pleurisy, oftner dull. A pain is said to affect the clavicle, and top of the right shoulder; with difficulty in lying on the left side; difficult respiration; dry cough; vomiting; hiccough. There is another hepatitis mentioned by authors, in which the fever, and other symptoms, are wanting, or are less violent; as described in Class II. 1. 4. 12. and which is probably sometimes relieved by eruptions of the face; as in those who are habituated to the intemperate use of fermented liquors. M. M. Hepatic inflammation is very liable to terminate in suppuration, and the patient is destroyed by the continuance of a fever with sizy blood, but without night-sweats, or diarrhoea, as in other unopened abscesses. Whence copious and repeated venesection is required early in the disease, with repeated doses of calomel, and cathartics. Warm bath. Towards the end of the disease small doses of opium before the evening paroxysms, and lastly the Peruvian bark, and chalybeate wine, at first in small doses, as 20 drops twice a day, and afterwards, if necessary, in larger. See Art. IV. 2. 6. Mrs. C. a lady in the last month of her pregnancy, was seized with violent hepatitis, with symptoms both of peripneumony and of pleurisy, for it seldom happens in violent inflammations, that one viscus alone is affected; she wanted then about a fortnight of her delivery, and after frequent venesection, with gentle cathartics, with fomentation or warm bath, she recovered and was safely delivered, and both herself and child did well. Rheumatic and eruptive fevers are more liable to induce abortion. 13. _Splenitis._ Inflammation of the spleen commences with tension, heat, and tumour of the left side, and with pain, which is increased by pressure. A case is described in Class I. 2. 3. 18. where a tumid spleen, attended with fever, terminated in schirrus of that viscus. 14. _Nephritis._ Inflammation of the kidney seems to be of two kinds; each of them attended with different symptoms, and different modes of termination. One of them I suppose to be an inflammation of the external membrane of the kidney, arising from general causes of inflammation, and accompanied with pain in the loins without vomiting; and the other to consist in an inflammation of the interior parts of the kidney, occasioned by the stimulus of gravel in the pelvis of it, which is attended with perpetual vomiting, with pain along the course of the ureter, and retraction of the testis on that side, or numbness of the thigh. The former of these kinds of nephritis is distinguished from lumbago by its situation being more exactly on the region of the kidney, and by its not being extended beyond that part; after three or four days I believe this inflammation is liable to change place; and that a herpes or erysipelas, called zona, or shingles, breaks out about the loins in its stead; at other times it is cured by a cathartic with calomel, with or without previous venesection. The other kind of nephritis, or inflammation of the interior part of the kidney, generally arises from the pain occasioned by the stimulus of a stone entering the ureter from the pelvis of the kidney; and, which ceases when the stone is protruded forwards into the bladder; or when it is returned into the pelvis of the kidney by the retrograde action of the ureter. The kidney is nevertheless inflamed more frequently, though in a less degree, from other causes; especially from the intemperate ingurgitation of ale, or other fermented or spirituous liquors. This less degree of inflammation is the cause of gravel, as that before mentioned is the effect of it. The mucus secreted to lubricate the internal surface of the uriniferous tubes of the kidney becomes secreted in greater quantity, when these vessels are inflamed; and, as the correspondent absorbent vessels act more energetically at the same time, the absorption of its more fluid parts is more powerfully effected; on both these accounts the mucus becomes both changed in quality and more indurated. And in this manner stones are produced on almost every mucous membrane of the body; as in the lungs, bowels, and even in the pericordium, as some writers have affirmed. See Class I. 1. 3. 9. M. M. Venesection. Ten grains of calomel given in small pills, then infusion of sena with oil. Warm bath. Then opium a grain and half. See Class I. 1. 3. 9. for a further account of the method of cure. 15. _Cystitis._ Inflammation of the bladder is attended with tumor and pain of the lower part of the belly; with difficult and painful micturition; and tenesmus. It generally is produced by the existence of a large stone in the bladder, when in a great degree; or is produced by common causes, when in a slighter degree. The stone in the bladder is generally formed in the kidney, and passing down the ureter into the bladder becomes there gradually increased in size; and this most frequently by the apposition of concentric spheres, as may be seen by sawing some of the harder calculi through the middle, and polishing one surface. These new concretions superinduced on the nucleus, which descended from the kidney, as described in Class I. 1. 3. 9. and in the preceding article of this genus, is not owing to the microcosmic salt, which is often seen to adhere to the sides of chamber-pots, as this is soluble in warm water, but to the mucus of the bladder, as it rolls along the internal surface of it. Now when the bladder is slightly inflamed, this mucus of its internal surface is secreted in greater quantity, and is more indurated by the absorption of its more liquid part at the instant of secretion, as explained in Class I. 1. 3. 9. and II. 1. 2. 14. and thus the stimulus and pain of a stone in the bladder contributes to its enlargement by inflaming the interior coat of it. M. M. Venesection. Warm bath. Diluents. Anodyne clysters. See Class I. 1. 3. 9. 16. _Hysteritis._ Inflammation of the womb is accompanied with heat, tension, tumor, and pain of the lower belly. The os uteri painful to the touch. Vomiting. This disease is generally produced by improper management in the delivery of pregnant women. I knew an unfortunate case, where the placenta was left till the next day; and then an unskilful accoucheur introduced his hand, and forcibly tore it away; the consequence was a most violent inflammatory fever, with hard throbbing pulse, great pain, very sizy blood, and the death of the patient. Some accoucheurs have had a practice of introducing their hand into the uterus immediately after the birth of the child, to take away the placenta; which they said was to save time. Many women I believe have been victims to this unnatural practice. Others have received injury, where inflammation has been beginning, by the universal practice of giving a large dose of opium immediately on delivery, without any indication of its propriety; which, though a proper and useful medicine, where the patient is too feeble, when given in a small dose, as 10 drops of tincture of opium, or half a grain of solid opium, must do a proportionate injury, when it is given improperly; and as delivery is a natural process, it is certainly more wise to give no medicines, except there be some morbid symptom, which requires it; and which has only been introduced into custom by the ill-employed activity of the Priests or Priestesses of LUCINA; like the concomitant nonsense of cramming rue or rheubarb into the mouth of the unfortunate young stranger, who is thus soon made to experience the evils of life. See Class II. 1. 1. 12. and I. 1. 2. 5. Just so some over-wise beldames force young ducks and turkeys, as soon as they are hatched, to swallow a peppercorn. M. M. Venesection repeatedly; diluents; fomentation; the patient should be frequently raised up in bed for a short time, to give opportunity of discharge to the putrid lochia; mucilaginous clysters. See Febris Puerpera. 17. _Lumbago sensitiva._ Sensitive lumbago. When the extensive membranes, or ligaments, which cover the muscles of the back are torpid, as in the cold paroxysm of ague, they are attended with pain in consequence of the inaction of the vessels, which compose them. When this inaction continues without a consequent renewal or increase of activity, the disease becomes chronical, and forms the lumbago frigida, or irritativa, described in Class I. 2. 4. 16. But when this cold fit or torpor of these membranes, or ligaments or muscles of the back, is succeeded by a hot fit, and consequent inflammation, a violent inflammatory fever, with great pain, occurs, preventing the erect posture of the body; and the affected part is liable to suppurate, in which case a very dangerous ulcer is formed, and a part of one of the vertebrae is generally found carious, and the patient sinks after a long time under the hectic fever occasioned by the aerated or oxygenated matter. This disease bears no greater analogy to rheumatism than the inflammation of the pleura, or any other membranous inflammation; and has therefore unjustly been arranged under that name. It is distinguished from nephritis, as it is seldom attended with vomiting, I suppose never, except the ureter happens to be inflamed at the same time. The pain sometimes extends on the outside of the thigh from the hip to the ankle, heel, or toes, and is then called sciatica; and has been thought to consist in an inflammation of the theca, or covering of the sciatic nerve, as the pain sometimes so exactly attends the principal branches of that nerve. See Class I. 2. 4. 15. 16. M. M. Venesection repeatedly; calomel; gentle cathartics; diluents; warm bath; poultice on the back, consisting of camomile flowers, turpentine, soap, and opium; a burgundy-pitch plaster. A debility of the inferior limbs from the torpor of the muscles, which had previously been too much excited, frequently occurs at the end of this disease; in this case electricity, and issues on each side of the lumber vertebræ, are recommended. See Class I. 2. 4. 16. 18. _Ischias._ The ischias consists of inflammatory fever, with great pain about the pelvis, the os coccigis, and the heads of the thigh-bones, preventing the patient from walking or standing erect, with increase of pain on going to stool. This malady, as well as the preceding, has been ascribed to rheumatism; with which it seems to bear no greater analogy, than the inflammations of any other membranes. The patients are left feeble, and sometimes lame after this disease; which is also sometimes accompanied with great flow of urine, owing to the defective absorption of its aqueous parts; and with consequent thirst occasioned by the want of so much fluid being returned into the circulation; a lodgment of fæces in the rectum sometimes occurs after this complaint from the lessened sensibility of it. See Class I. 2. 4. 15. M. M. Venesection; gentle cathartics; diluents; fomentation; poultice with camomile flowers, turpentine, soap, and opium; afterwards the bark. See Class I. 1. 3. 5. When this inflammation terminates in suppuration the matter generally can be felt to fluctuate in the groin, or near the top of the thigh. In this circumstance, my friend Mr. Bent, Surgeon near Newcastle in Staffordshire, proposes to tap the abscess by means of a trocar, and thus as often as necessary to discharge the matter without admitting the air. Might a weak injection of wine and water, as in the hydrocele, be used with great caution to inflame the walls of the abscess, and cause them to unite? See Class II. 1. 6. 9. 19. _Paronychia interna._ Inflammation beneath the finger-nail. The pain occasioned by the inflammatory action and tumor of parts bound down between the nail on one side and the bone on the other, neither of which will yield, is said to occasion so much pain as to produce immediate delirium, and even death, except the parts are divided by a deep incision; which must pass quite through the periosteum, as the inflammation is said generally to exist beneath it. This disease is thus resembled by the process of toothing in young children; where an extraneous body lodged beneath the periosteum induces pain and fever, and sometimes delirium, and requires to be set at liberty, by the lancet. * * * * * ORDO I. _Increased Sensation._ GENUS III. _With the Production of new Vessels by external Membranes or Glands with Fever._ The diseases of this genus are perhaps all productive of contagious matter; or which becomes so by its exposure to the air, either through the cuticle, or by immediate contact with it; such are the matters of the small-pox and measles. The purulent matter formed on parts covered from the air by thicker membranes or muscles, as in the preceding genus, does not induce fever, and cannot therefore be called contagious; but it acquires this property of producing fever in a few hours, after the abscess has been opened, so as to admit the air to its surface, and may then be said to consist of contagious miasmata. This kind of contagious matter only induces fever, but does not produce other matter with properties similar to its own; and in this respect it differs from the contagious miasmata of small-pox or measles, but resembles those which have their origin in crowded jails; for these produce fever only, which frequently destroys the patient; but do not produce other matters similar to themselves; as appears from none of those, who died of the jail-fever, caught at the famous black assizes at Oxford, at the beginning of this century, having infected their physicians or attendants. If indeed the matter has continued so long as to become putrid, and thus to have given out air from a part of it, it acquires the power of producing fever; in the same manner as if the ulcer had been opened, and exposed to the common air; instances of which are not unfrequent. And from these circumstances it seems probable, that the matters secreted by the new vessels formed in all kinds of phlegmons, or pustles, are not contagious, till they have acquired something from the atmosphere, or from the gas produced by putrefaction; which will account for some phenomena in the lues venerea, cancer, and of other contagious secretions on the skin without fever, to be mentioned hereafter. See Class II. 1. 4. 14. The theory of contagion has been perplexed by comparing it with fermenting liquors; but the contagious material is shewn in Section XXXIII. to be produced like other secreted matters by certain animal motions of the terminations of the vessels. Hence a new kind of gland is formed at the terminations of the vessels in the eruptions of the small-pox; the animal motions of which produce from the blood variolous matter; as other glands produce bile or saliva. Now if some of this matter is introduced beneath the cuticle of a healthy person, or enters the circulation, and excites the extremities of the blood-vessels into those kinds of diseased motions, by which it was itself produced, either by irritation or association, these diseased motions of the extremities of the vessels will produce other similar contagious matter. See Sect. XXXIII. 2. 5. and 9. Hence contagion seems to be propagated two ways; one, by the stimulus of contagious matter applied to the part, which by an unknown law of nature excites the stimulated vessels to produce a similar matter; as in venereal ulcers, which thus continue to spread; or as when variolous matter is inserted beneath the cuticle; or when it is supposed to be absorbed, and diffused over the body mixed with the blood, and applied in that manner to the cutaneous glands. The other way, by which contagion seems to be diffused, is by some distant parts sympathizing or imitating the motions of the part first affected; as the stomach and skin in the eruptions of the inoculated small-pox, or in the bite of a mad dog; as treated of in Sect. XXII. 3. 3. In some of the diseases of this genus the pulse is strong, full, and hard, constituting the sensitive irritated fever, as described in the preceding genus; as in one kind of erysipelas, which requires repeated venesection. In others the arterial action is sometimes moderate, so as to constitute the sensitive fever, as in the inoculated small-pox; where the action of the arteries is neither increased by the sensorial power of irritation, as in the sensitive irritated fever; nor decreased by the defect of that power, as in the sensitive inirritated fever. But in the greatest number of the diseases of this genus the arterial action is greatly diminished in respect to strength, and consequently the frequency of pulsation is proportionally increased, as explained in Sect XXXII. 2. 1. Which is owing to the deficiency of the sensorial power of irritation joined with the increase of that of sensation, and thus constitutes the sensitive inirritated fever; as in Scarlatina with gangrenous tonsils. From this great debility of the action of the arteries, there appears to be less of the coagulable lymph or mucus secreted on their internal surfaces; whence there is not only a defect of that buff or size upon the blood, which is seen on the surface of that, which is drawn in the sensitive irritated fever; but the blood, as it cools, when it has been drawn into a bason, scarcely coagulates; and is said to be dissolved, and is by some supposed to be in a state of actual putrefaction. See Sect. XXXIII. 1. 3. where the truth of this idea is controverted. But in the fevers of both this genus and the preceding one great heat is produced from the chemical combinations in the secretions of new vessels and fluids, and pain or uneasiness from the distention of the old ones; till towards the termination of the disease sensation ceases, as well as irritation, with the mortification of the affected parts, and the death of the patient. Dysenteria, as well as tonsillitis and aphtha, are enumerated amongst the diseases of external membranes, because they are exposed either to the atmospheric air, which is breathed, and swallowed with our food and saliva; or they are exposed to the inflammable air; or hydrogen, which is generated in the intestines; both which contribute to produce or promote the contagious quality of these fluids; as mentioned in Class II. 1. 5. It is not speaking accurate language, if we say, that in the diseases of this genus the fever is contagious; since it is the material produced by the external membranes, which is contagious, after it has been exposed to air; while the fever is the consequence of this contagious matter, and not the cause of it. As appears from the inoculated small-pox, in which the fever does not commence, till after suppuration has taken place in the inoculated arm, and from the diseases of the fifth genus of this order, where contagion exists without fever. See Class II. 1. 5. and II. 1. 3. 18. SPECIES. 1. _Febris sensitiva inirritata._ Sensitive inirritated fever. Typhus gravior. Putrid malignant fever. Jail fever. The immediate cause of this disease is the increase of the sensorial power of sensation, joined with the decrease of the sensorial power of irritation; that is, it consists in the febris sensitiva joined with the febris inirritativa of Class I. 2. 1. 1. as the febris sensitiva irritata of the preceding genus consists of the febris sensitiva joined with the febris irritativa of Class I. 1. 1. 1. In both which the word irritata, and inirritata, are designed to express more or less irritation than the natural quantity; and the same when applied to some of the diseases of this genus. This fever is frequently accompanied with topical inflammation, which is liable, if the arterial strength is not supported, to end in sphacelus; and as mortified parts, such as sloughs of the throat, if they adhere to living parts, soon become putrid from the warmth and moisture of their situation; these fevers have been termed putrid, and have been thought to owe their cause to what is only their consequence. In hot climates this fever is frequently induced by the exhalations of stagnating lakes or marshes, which abound with animal substances; but which in colder countries produce fevers with debility only, as the quartan ague, without inflammation. The sensitive inirritated, or malignant, fever is also frequently produced by the putrid exhalations and stagnant air in prisons; but perhaps most frequently by contact or near approach of the persons, who have resided in them. These causes of malignant fevers contributed to produce, and to support for a while, the septic and antiseptic theory of them; see Sect. XXXIII. 1. 3. The vibices or bruises, and petechiæ or purples, were believed to be owing to the dissolved state of the blood by its incipient putrefaction; but hydrostatical experiments have been made, which shew the sizy blood of the patient in sensitive irritated or inflammatory fever, with strong pulse, is more fluid, while it is warm, than this uncoagulable blood taken in this sensitive inirritated, or malignant fever; from whence it is inferred, that these petechiæ, and vibices, are owing to the deficient power of absorption in the terminations of the veins, See Class I. 2. 1. 5. This sensitive inirritated fever, or typhus gravior, is distinguished from the inirritative fever, or typhus mitior, in the early stages of it, by the colour of the skin; which in the latter is paler, with less heat, owing to the less violent action of the capillaries; in this it is higher coloured, and hotter, from the greater energy of the capillary action in the production of new vessels. In the more advanced state petechiæ, and the production of contagious matter from inflamed membranes, as the aphthæ of the mouth, or ulcers of the throat, distinguishes this fever from the former. Delirium, and dilated pupils of the eyes, are more frequent in nervous fevers; and stupor with deafness more frequent attendants on malignant fevers. See Class I. 2. 5. 6. There is another criterion discernible by the touch of an experienced finger; and that is, the coat of the artery in inflammatory fevers, both those attended with strength of pulsation, and these with weak pulsation, feels harder, or more like a cord; for the coats of the arteries in these fevers are themselves inflamed, and are consequently turgid with blood, and thence are less easily compressed, though their pulsations are nevertheless weak: when the artery is large or full with an inflamed coat, it is called hard; and when small or empty with an inflamed coat, it is called sharp, by many writers. M. M. The indications of cure consist, 1. In procuring a regurgitation of any offensive material, which may be lodged in the long mouths of the lacteals or lymphatics, or in their tumid glands. 2. To excite the system into necessary action by the repeated exhibition of nutrientia, sorbentia, and incitantia; and to preserve the due evacuation of the bowels. 3. To prevent any unnecessary expenditure of sensorial power. 4. To prevent the formation of ulcers, or to promote the absorption in them, for the purpose of healing them. 1. One ounce of wine of ipecacuanha, or about ten grains of the powder, should be given as an emetic. After a few hours three or four grains of calomel should be given in a little mucilage, or conserve. Where something swallowed into the stomach is the cause of the fever, it is liable to be arrested by the lymphatic glands, as the matter of the small-pox inoculated in the arm is liable to be stopped by the axillary lymphatic gland; in this situation it may continue a day or two, or longer, and may be regurgitated during the operation of an emetic or cathartic into the stomach or bowel, as evidently happens on the exhibition of calomel, as explained in Sect. XXIX. 7. 2. For this reason an emetic and cathartic, with venesection, if indicated by the hardness and fulness of the pulse, will very frequently remove fevers, if exhibited on the first, second, or even third day. 2. Wine and opium, in small doses repeated frequently, but so that not the least degree of intoxication follows, for in that case a greater degree of debility is produced from the expenditure of sensorial power in unnecessary motions. Many weak patients have been thus stimulated to death. See Sect. XII. 7. 8. The Peruvian bark should be given also in repeated doses in such quantity only as may strengthen digestion, not impede it. For these purposes two ounces of wine, or of ale, or cyder, should be given every six hours; and two ounces of decoction of bark, with two drachms of the tincture of bark, and six drops of tincture of opium, should be given also every six hours alternately; that is, each of them four times in twenty-four hours. As much rhubarb as may induce a daily evacuation, should be given to remove the colluvies of indigested materials from the bowels; which might otherwise increase the distress of the patient by the air it gives out in putrefaction, or by producing a diarrhoea by its acrimony; the putridity of the evacuations are in consequence of the total inability of the digestive powers; and their delay in the intestines, to the inactivity of that canal in respect to its peristaltic motions. The quantities of wine or beer and opium, and bark, above mentioned, may be increased by degrees, if the patient seems refreshed by them; and if the pulse becomes slower on their exhibition; but this with caution, as I have seen irrecoverable mischief done by greater quantities both of opium, wine, and bark, in this kind of fever; in which their use is to strengthen the digestion of the weak patient, rather than to stop the paroxysms of fever; but when they are administered in intermittents, much larger quantities are necessary. The stimulus of small blisters applied in succession, one every three or four days, when the patient becomes weak, is of great service by strengthening digestion, and by preventing the coldness of the extremities, owing to the sympathy of the skin with the stomach, and of one part of the skin with another. In respect to nutriment, the patient should be supplied with wine and water, with toasted bread, and sugar or spice in it; or with sago with wine; fresh broth with turnips, cellery, parsley; fruit; new milk. Tea with cream and sugar; bread pudding, with lemon juice and sugar; chicken, fish, or whatever is grateful to the palate of the sick person, in small quantity repeated frequently; with small beer, cyder and water, or wine and water, for drink, which may be acidulated with acid of vitriol in small quantities. 3. All unnecessary motions are to be checked, or prevented. Hence horizontal posture, obscure room, silence, cool air. All the parts of the skin, which feel too hot to the hand, should be exposed to a current of cool air, or bathed with cold water, whether there are eruptions on it or not. Wash the patient twice a day with cold vinegar and water, or cold salt and water, or cold water alone, by means of a sponge. If some parts are too cold, as the extremities, while other parts are too hot, as the face or breast, cover the cold parts with flannel, and cool the hot parts by a current of cool air, or bathing them as above. 4. For the healing of ulcers, if in the mouth, solution of alum in water about 40 grains to an ounce, or of blue vitriol in water, one grain or two to an ounce may be used to touch them with three or four times a day. Of these perhaps a solution of alum is to be preferred, as it instantly takes away the stench from ulcers I suppose by combining with the volatile alcali which attends it. For this purpose a solution of alum of an ounce to a pint of water should be frequently injected by means of a syringe into the mouth. If there are ulcers on the external skin, fine powder of bark seven parts, and cerusia in fine powder one part, should be mixed, and applied dry on the sore, and kept on by lint, and a bandage. As sloughs in the mouth are frequently produced by the previous dryness of the membranes, which line it, this dryness should be prevented by frequently moistening them, which may be effected by injection with a syringe, or by a moist sponge, or lastly in the following manner. Place a glass of wine and water, or of milk and sugar, on a table by the bedside, a little above the level of the mouth of the patient; then, having previously moistened a long piece of narrow listing, or cloth, or flannel, with the same liquor, leave one end of it in the glass, and introduce the other into the mouth of the patient; which will thus be supplied with a constant oozing of the fluid through the cloth, which acts as a capillary syphon. The viscid phlegm, which adheres to the tongue, should be coagulated by some austere acid, as by lemon-juice evaporated to half its quantity, or by crab-juice; and then it may be scraped off by a knife, or rubbed off by flannel, or a sage leaf dipped in vinegar, or in salt and water. 2. _Erysipelas_, St. Anthony's fire, may be divided into three kinds, which differ in their method of cure, the irritated, the inirritated, and the sensitive erysipelas. _Erysipelas irritatum_ is attended with increase of irritation besides increase of sensation; that is, with strong, hard, and full pulse, which requires frequent venesection, like other inflammations with arterial strength. It is distinguished from the phlegmonic inflammations of the last genus by its situation on the external habit, and by the redness, heat, and tumour not being distinctly circumscribed; so that the eye or finger cannot exactly trace the extent of them. When the external skin is the seat of inflammation, and produces sensitive irritated fever, no collection of matter is formed, as when a phlegmon is situated in the cellular membrane beneath the skin; but the cuticle rises as beneath a blister-plaster, and becomes ruptured; and a yellow material oozes out, and becomes inspissated, and lies upon its surface; as is seen in this kind of erysipelas, and in the confluent small-pox; or if the new vessels are reabsorbed the cuticle peels off in scales. This difference of the termination of erysipelatous and phlegmonic inflammation seems to be owing in part to the less distensibility of the cuticle than of the cellular membrane, and in part to the ready exhalation of the thinner parts of the secreted fluids through its pores. This erysipelas is generally preceded by a fever for two or three days before the eruption, which is liable to appear in some places, as it declines in others; and seems frequently to arise from a previous scratch or injury of the skin; and is attended sometimes with inflammation of the cellular membrane beneath the skin; whence a real phlegmon and collection of matter becomes joined to the erysipelas, and either occasions or increases the irritated fever, which attends it. There is a greater sympathy between the external skin and the meninges of the brain, than between the cellular membrane and those meninges; whence erysipelas is more liable to be preceded or attended, or succeeded, by delirium than internal phlegmons. I except the mumps, or parotitis, described below; which is properly an external gland, as its excretory duct opens into the air. When pain of the head or delirium precedes the cutaneous eruption of the face, there is some reason to believe, that the primary disease is a torpor of the meninges of the brain; and that the succeeding violent action is transferred to the skin of the face by sensitive association; and that a similar sympathy occurs between some internal membranes and the skin over them, when erysipelas appears on other parts of the body. If this circumstance should be supported by further evidence, this disease should be removed into Class IV. along with the rheumatism and gout. See Class IV. 1. 2. 17. This supposed retropulsion of erysipelas on the brain from the frequent appearance of delirium, has prevented the free use of the lancet early in this disease to the destruction of many; as it has prevented the subduing of the general inflammation, and thus has in the end produced the particular one on the brain. Mr. B----, a delicate gentleman about sixty, had an erysipelas beginning near one ear, and extending by degrees over the whole head, with hard, full, and strong pulse; blood was taken from him four or five times in considerable quantity, with gentle cathartics, with calomel, diluents, and cool air, and he recovered without any signs of delirium, or inflammation of the meninges of the brain. Mr. W----, a strong corpulent man of inferior life, had erysipelas over his whole head, with strong hard pulse: he was not evacuated early in the disease through the timidity of his apothecary, and died delirious. Mrs. F---- had erysipelas on the face, without either strong or weak pulse; that is, with sensitive fever alone, without superabundance or deficiency of irritation; and recovered without any but natural evacuations. From these three cases of erysipelas on the head it appears, that the evacuations by the lancet must be used with courage, where the degree of inflammation requires it; but not where this degree of inflammation is small, nor in the erysipelas attended with inirritation, as described below. M. M. Venesection repeated according to the degree of inflammation. An emetic. Calomel three grains every other night. Cool air. Diluents, emetic tartar in small doses, as a quarter of a grain every six hours. Tea, weak broth, gruel, lemonade, neutral salts. See Sect. XII. 6. Such external applications as carry away the heat of the skin may be of service, as cold water, cold flour, snow, ether. Because these applications impede the exertions of the secerning vessels, which are now in too great action; but any applications of the stimulant kind, as solutions of lead, iron, copper, or of alum, used early in the disease, must be injurious; as they stimulate the secerning vessels, as well as the absorbent vessels, into greater action; exactly as occurs when stimulant eye-waters are used too soon in ophthalmy. See Class II. 1. 2. 2. But as the cuticle peels off in this case after the inflammation ceases, it differs from ophthalmy; and stimulant applications are not indicated at all, except where symptoms of gangrene appear. For as a new cuticle is formed under the old one, as under a blister, the serous fluid between them is a defence to the new cuticle, and should dry into a scab by exhalation rather than be reabsorbed. Hence we see how greasy or oily applications, and even how moist ones, are injurious in erysipelas; because they prevent the exhalation of the serous effusion between the old and new cuticle, and thus retard the formation of the latter. _Erysipelas inirritatum_ differs from the former in its being attended with weak pulse, and other symptoms of sensitive inirritated fever. The feet and legs are particularly liable to this erysipelas, which precedes or attends the sphacelus or mortification of those parts. A great and long coldness first affects the limb, and the erysipelas on the skin seems to occur in consequence of the previous torpor of the interior membranes. As this generally attends old age, it becomes more dangerous in proportion to the age, and also to the habitual intemperance of the patient in respect to the use of fermented or spirituous liquor. When the former kind, or irritated erysipelas, continues long, the patient becomes so weakened as to be liable to all the symptoms of this inirritated erysipelas; especially where the meninges of the brain are primarily affected. As in that case, after two or three efforts have been made to remove the returning periods of torpor of the meninges to the external skin, those meninges become inflamed themselves, and the patient sinks under the disease; in a manner similar to that in old gouty patients, where the torpor of the liver or stomach is relieved by association of the inflammation of the membranes of the feet, and then of other joints, and lastly the power of association ceasing to act, but the excess of sensation continuing, the liver or stomach remains torpid, or become themselves inflamed, and the patient is destroyed. M. M. Where there exists a beginning gangrene of the extremities, the Peruvian bark, and wine, and opium, are to be given in large quantities; so as to strengthen the patient, but not to intoxicate, or to impede his digestion of aliment, as mentioned in the first species of this genus. Class II. 1. 2. 1. But where the brain is inflamed or oppressed, which is known either by delirium, with quick pulse; or by stupor, and slow respiration with slow pulse; other means must be applied. Such as, first, a fomentation on the head with warm water, with or without aromatic herbs, or salt in it, should be continued for an hour or two at a time, and frequently repeated. A blister may also be applied on the head, and the fomentation nevertheless occasionally repeated. Internally very gentle stimulants, as camphor one grain or two in infusion of valerian. Wine and water or small beer, weak broth. An enema. Six grains of rhubarb and one of calomel. Afterwards five drops of tincture of opium, which may be repeated every six hours, if it seems of service. Might the head be bathed for a minute with cold water? or with ether? or vinegar? _Erysipelas sensitivum_ is a third species, differing only in the kind of fever which attends it, which is simply inflammatory, or sensitive, without either excess of irritation, as in the first variety; or the defect of irritation, as in the second variety: all these kinds of erysipelas are liable to return by periods in some people, who have passed the middle of life, as at periods of a lunation, or two lunations, or at the equinoxes. When these periods of erysipelas happen to women, they seem to supply the place of the receding catamenia; when to men, I have sometimes believed them to be associated with a torpor of the liver; as they generally occur in those who have drank vinous spirit excessively, though not approbriously; and that hence they supply the place of periodical piles, or gout, or gutta rosea. M. M. As the fever requires no management, the disease takes its progress safely, like a moderate paroxysm of the gout; but in this case, as in some of the former, the erysipelas does not appear to be a primary disease, and should perhaps be removed to the Class of Association. 3. _Tonsillitis._ Inflammation of the tonsils. The uncouth term Cynanche has been used for diseases so dissimilar, that I have divided them into Tonsillitis and Parotitis; and hope to be excused for adding a Greek termination to a Latin word, as one of those languages may justly be considered as a dialect of the other. By tonsillitis the inflammation of the tonsils is principally to be understood; but as all inflammations generally spread further than the part first affected; so, when the summit of the windpipe is also much inflamed, it may be termed tonsillitis trachealis, or croup. See Class I. 1. 3. 4. and II. 1. 2. 4.; and when the summit of the gullet is much inflamed along with the tonsil, it may be called tonsillitis pharyngea, as described in Dr. Cullen's Nosologia, Genus X. p. 92. The inflammation of the tonsils may be divided into three kinds, which require different methods of cure. _Tonsillitis interna._ Inflammation of the internal tonsil. When the swelling is so considerable as to produce difficulty of breathing, the size of the tonsil should be diminished by cutting it with a proper lancet, which may either give exit to the matter it contains, or may make it less by discharging a part of the blood. This kind of angina is frequently attended with irritated fever besides the sensitive one, which accompanies all inflammation, and sometimes requires venesection. An emetic should be given early in the disease, as by its inducing the retrograde action of the vessels about the fauces during the nausea it occasions, it may eliminate the very cause of the inflammation; which may have been taken up by the absorbents, and still continue in the mouths of the lymphatics or their glands. The patient should then be induced to swallow some aperient liquid, an infusion of senna, so as to induce three or four evacuations. Gargles of all kinds are rather hurtful, as the action of using them is liable to give pain to the inflamed parts; but the patients find great relief from frequently holding warm water in their mouths, and putting it out again, or by syringing warm water into the mouth, as this acts like a warm bath or fomentation to the inflamed part. Lastly, some mild stimulant, as a weak solution of salt and water, or of white vitriol and water, may be used to wash the fauces with in the decline of the disease, to expedite the absorption of the new vessels, if necessary, as recommended in ophthalmy. _Tonsillitis superficialis._ Inflammation of the surface of the tonsils. As the tonsils and parts in their vicinity are covered with a membrane, which, though exposed to currents of air, is nevertheless constantly kept moist by mucus and saliva, and is liable to diseases of its surface like other mucous membranes, as well as to suppuration of the internal substance of the gland; the inflammation of its surface is succeeded by small elevated pustules with matter in them, which soon disappears, and the parts either readily heal, or ulcers covered with sloughs are left on the surface. This disease is generally attended with only sensitive fever, and therefore is of no danger, and may be distinguished with great certainty from the dangerous inflammation or gangrene of the tonsils at the height of the small-pox, or scarlet fever, by its not being attended with other symptoms of those diseases. One emetic and a gentle cathartic is generally sufficient; and the frequent swallowing of weak broth, or gruel, both without salt in them, relieves the patient, and absolves the cure. When these tumours of the tonsils frequently return I have sometimes suspected them to originate from the absorption of putrid matter from decaying teeth. See Class I. 2. 3. 21. and II. 2. 2. 1. _Tonsillitis inirritata._ Inflammation of the tonsils with sensitive inirritated fever is a symptom only of contagious fever, whether attended with scarlet eruption, or with confluent small-pox, or otherwise. The matter of contagion is generally diffused, not dissolved in the air; and as this is breathed over the mucaginous surface of the tonsils, the contagious atoms are liable to be arrested by the tonsil; which therefore becomes the nest of the future disease, like the inflamed circle round the inoculated puncture of the arm in supposititious small-pox. This swelling is liable to suffocate the patient in small-pox, and to become gangrenous in scarlet fever, and some other contagious fevers, which have been received in this manner. The existence of inflammation of the tonsil previous to the scarlet eruption, as the arm inflames in the inoculated small-pox, and suppurates before the variolous eruption, should be a criterion of the scarlet fever being taken in this manner. M. M. All the means which strengthen the patient, as in the sensitive inirritated fever, Class II. 1. 2. 1. As it is liable to continue a whole lunation or more, great attention should be used to nourish the patient with acidulous and vinous panada, broth with vegetables boiled in it, sugar, cream, beer; all which given frequently will contribute much to moisten, clean, and heal the ulcuscles, or sloughs, of the throat; warm water and wine, or acid of lemon, should be frequently applied to the tonsils by means of a syringe, or by means of a capillary syphon, as described in Class II. 1. 3. 1. A slight solution of blue vitriol, as two grains to an ounce, or a solution of sugar of lead of about six grains to an ounce, may be of service; especially the latter, applied to the edges of the sloughs, drop by drop by means of a small glass tube, or small crow-quill with the end cut off, or by a camel's-hair pencil or sponge; to the end of either of which a drop will conveniently hang by capillary attraction; as solutions of lead evidently impede the progress of erysipelas on the exterior skin, when it is attended with feeble pulse. Yet a solution of alum injected frequently by a syringe is perhaps to be preferred, as it immediately removes the fetor of the breath, which must much injure the patient by its being perpetually received into the lungs by respiration. 4. _Parotitis._ Mumps, or branks, is a contagious inflammation of the parotis and maxillary glands, and has generally been classed under the word Cynanche or Angina, to which it bears no analogy. It divides itself into two kinds, which differ in the degree of fever which attends them, and in the method of cure. _Parotitis suppurans._ The suppurating mumps is to be distinguished by the acuteness of the pain, and the sensitive, irritated, or inflammatory fever, which attends it. M. M. Venesection. Cathartic with calomel three or four grains repeatedly. Cool air, diluents. This antiphlogistic treatment is to be continued no longer than is necessary to relieve the violence of the pain, as the disease is attended with contagion, and must run through a certain time, like other fevers with contagion. _Parotitis mutabilis._ Mutable parotitis. A sensitive fever only, or a sensitive irritated fever, generally attends this kind. And when the tumor of the parotis and maxillary glands subsides, a new swelling occurs in some distant part of the system; as happens to the hands and feet, at the commencement of the secondary fever of the small-pox, when the tumor of the face subsides. This new swelling in the parotitis mutabilis is liable to affect the testes in men, and form a painful tumor, which should be prevented from suppuration by very cautious means, if the violence of the pain threaten such a termination; as by bathing the part with coldish water for a time, venesection, a cathartic; or by a blister on the perinæum, or scrotum, or a poultice. When women are affected with this complaint, after the swelling of the parotis and maxillary glands subsides, a tumor with pain is liable to affect their breasts; which, however, I have never seen terminate in suppuration. On the retrocession of the tumor of the testes above described, and I suppose of that of the breasts in women, a delirium of the calm kind is very liable to occur; which in some cases has been the first symptom which has alarmed the friends of the patient; and it has thence been difficult to discover the cause of it without much inquiry; the previous symptoms having been so slight as not to have occasioned any complaints. In this delirium, if the pulse will bear it, venesection should be used, and three or four grains of calomel, with fomentation of the head with warm water for an hour together every three or four hours. Though this disease generally terminates favourably, considering the numbers attacked by it, when it is epidemic, yet it is dangerous at other times in every part of its progress. Sometimes the parotis or maxillary glands suppurate, producing ulcers which are difficult to cure, and frequently destroy the patient, where there was a previous scrophulous tendency. The testis in men is also liable to suppurate with great pain, long confinement, and much danger; and lastly the affection of the brain is fatal to many. Mr. W. W. had a swelled throat, which after a few days subsided. He became delirious or stupid, in which state he was dying when I saw him; and his friends ascribed his death to a coup de soleil, which he was said to have received some months before, when he was abroad. Mr. A. B. had a swelling of the throat, which after a few days subsided. When I saw him he had great stupor, with slow breathing, and partial delirium. On fomenting his head with warm water for an hour these symptoms of stupor were greatly lessened, and his oppressed breathing gradually ceased, and he recovered in one day. Mr. C. D. I found walking about the house in a calm delirium without stupor; and not without much inquiry of his friends could get the previous history of the disease; which had been attended with parotitis, and swelled testis, previous to the delirium. A few ounces of blood were taken away, a gentle cathartic was directed, and his head fomented with warm water for an hour, with a small blister on the back, and he recovered in two or three days. Mr. D. D. came down from London in the coach alone, so that no previous history could be obtained. He was walking about the house in a calm delirium, but could give no sensible answers to any thing which was proposed to him. His pulse was weak and quick. Cordials, a blister, the bark, were in vain exhibited, and he died in two or three days. Mr. F. F. came from London in the same manner in the coach. He was mildly delirious with considerable stupor, and moderate pulse, and could give no account of himself. He continued in a kind of cataleptic stupor, so that he would remain for hours in any posture he was placed, either in his chair, or in bed; and did not attempt to speak for about a fortnight; and then gradually recovered. These two last cases are not related as being certainly owing to parotitis, but as they might probably have that origin. The parotitis suppurans, or mumps with irritated fever, is at times epidemic among cats, and may be called _parotitis felina_; as I have reason to believe from the swellings under the jaws, which frequently suppurate, and are very fatal to those animals. In the village of Haywood, in Staffordshire, I remember a whole breed of Persian cats, with long white hair, was destroyed by this malady, along with almost all the common cats of the neighbourhood; and as the parotitis or mumps had not long before prevailed amongst human beings in that part of the country, I recollect being inclined to believe, that the cats received the infection from mankind; though in all other contagious diseases, except the rabies canina can be so called, no different genera of animals naturally communicate infection to each other; and I am informed, that vain efforts have been made to communicate the small-pox and measles to some quadrupeds by inoculation. A disease of the head and neck destroyed almost all the cats in Westphalia. Savage, Nosol. Class X. Art. 30. 8. 5. _Catarrhus sensitivus_ consists of an inflammation of the membrane, which lines the nostrils and fauces. It is attended with sensitive fever alone, and is cured by the steam of warm water externally, and by diluents internally, with moderate venesection and gentle cathartics. This may be termed catarrhus sensitivus, to distinguish it from the catarrhus contagiosus, and is in common language called a violent cold in the head; it differs from the catarrhus calidus, or warm catarrh, of Class I. 1. 2. 7. in the production of new vessels, or inflammation of the membrane, and the consequent more purulent appearance of the discharge. Raucedo catarrhalis, or catarrhal hoarseness, is a frequent symptom of this disease, and is occasioned by the pain or soreness which attends the thickened and inflamed membranes of the larynx; which prevents the muscles of vocallity from sufficiently contracting the aperture of it. It ceases with the inflammation, or may be relieved by the steam of warm water alone, or of water and vinegar, or of water and ether. See Paralytic Hoarseness, Class III. 2. 1. 4. 6. _Catarrhus contagiosus._ This malady attacks so many at the same time, and spreads gradually over so great an extent of country, that there can be no doubt but that it is disseminated by the atmosphere. In the year 1782 the sun was for many weeks obscured by a dry fog, and appeared red as through a common mist. The material, which thus rendered the air muddy, probably caused the epidemic catarrh, which prevailed in that year, and which began far in the north, and extended itself over all Europe. See Botanic Garden, Vol. II. note on Chunda, and Vol. I. Canto IV, line 294, note; and was supposed to have been thrown out of a volcano, which much displaced the country of Iceland. In many instances there was reason to believe, that this disease became contagious, as well as epidemic; that is, that one person might receive it from another, as well as by the general unsalutary influence of the atmosphere. This is difficult to comprehend, but may be conceived by considering the increase of contagious matter in the small-pox. In that disease one particle of contagious matter stimulates the skin of the arm in inoculation into morbid action so as to produce a thousand particles similar to itself; the same thing occurs in catarrh, a few deleterious atoms stimulate the mucous membrane of the nostrils into morbid actions, which produce a thousand other particles similar to themselves. These contagious particles diffused in the air must have consisted of animal matter, otherwise how could an animal body by being stimulated by them produce similar particles? Could they then have had a volcanic origin, or must they not rather have been blown from putrid marshes full of animal matter? But the greatest part of the solid earth has been made from animal and vegetable recrements, which may be dispersed by volcanos.--Future discoveries must answer these questions. As the sensitive fever attending these epidemic catarrhs is seldom either much irritated or inirritated, venesection is not always either clearly indicated or forbid; but as those who have died of these catarrhs have generally had inflamed livers, with consequent suppuration in them, venesection is adviseable, wherever the cough and fever are greater than common, so as to render the use of the lancet in the least dubious. And in some cases a second bleeding was necessary, and a mild cathartic or two with four grains of calomel; with mucilaginous subacid diluents; and warm steam occasionally to alleviate the cough, finished the cure. The catarrhus contagiosus is a frequent disease amongst horses and dogs; it seems first to be disseminated amongst these animals by miasmata diffused in the atmosphere, because so many of them receive it at the same time; and afterwards to be communicable from one horse or dog to another by contagion, as above described. These epidemic or contagious catarrhs more frequently occur amongst dogs and horses than amongst men; which is probably owing to the greater extension and sensibility of the mucous membrane, which covers the organ of smell, and is diffused over their wide nostrils, and their large maxillary and frontal cavities. And to this circumstance may be ascribed the greater fatality of it to these animals. In respect to horses, I suspect the fever at the beginning to be of the sensitive, irritated, or inflammatory kind, because there is so great a discharge of purulent mucus; and that therefore they will bear once bleeding early in the disease; and also one mild purgative, consisting of about half an ounce of aloe, and as much white hard soap, mixed together. They should be turned out to grass both day and night for the benefit of pure air, unless the weather be too cold (and in that case they should be kept in an open airy stable, without being tied), that they may hang down their heads to facilitate the discharge of the mucus from their nostrils. Grass should be offered them, or other fresh vegetables, as carrots and potatoes, with mashes of malt, or of oats, and with plenty of fresh warm or cold water frequently in a day. When symptoms of debility appear, which may be known by the coldness of the ears or other extremities, or when sloughs can be seen on the membrane which lines the nostrils, a drink consisting of a pint of ale with half an ounce of tincture of opium in it, given every six hours, is likely to be of great utility. In dogs I believe the catarrh is generally joined with symptoms of debility early in the disease. These animals should be permitted to go about in the open air, and should have constant access to fresh water. The use of being as much as may be in the air is evident, because all the air which they breathe passes twice over the putrid sloughs of the mortified parts of the membrane which lines the nostrils, and the maxillary and frontal cavities; that is, both during inspiration and expiration; and must therefore be loaded with contagious particles. Fresh new milk, and fresh broth, should be given them very frequently, and they should be suffered to go amongst the grass, which they sometimes eat for the purpose of an emetic; and if possible should have access to a running stream of water. As the contagious mucus of the nostrils, both of these animals and of horses, generally drops into the water they attempt to drink. Bits of raw flesh, if the dog will eat them, are preferred to cooked meat; and from five to ten drops of tincture of opium may be given with advantage, when symptoms of debility are evident, according to the size of the dog, every six hours. If sloughs can be seen in the nostrils, they should be moistened twice a day, both in horses and dogs, with a solution of sugar of lead, or of alum, by means of a sponge fixed on a bit of whale bone, or by a syringe. The lotion may be made by dissolving half an ounce of sugar of lead in a pint of water. Ancient philosophers seem to have believed, that the contagious miasmata in their warm climates affected horses and dogs previous to mankind. If those contagious particles were supposed to be diffused amongst the heavy inflammable air, or carbonated hydrogen, of putrid marshes, as these animals hold their heads down lower to the ground, they may be supposed to have received them sooner than men. And though men and quadrupeds might receive a disease from the same source of marsh-putrefaction, they might not afterwards be able to infect each other, though they might infect other animals of the same genus; as the new contagious matter generated in their own bodies might not be precisely similar to that received; as happened in the jail-fever at Oxford, where those who took the contagion and died, did not infect others. On mules and dogs the infection first began, And, last, the vengeful arrows fix'd on man. POPE'S Homer's Iliad, I. 7. _Peripneumonia superficialis._ The superficial or spurious peripneumony consists in an inflammation of the membrane, which lines the bronchia, and bears the same analogy to the true peripneumony, as the inflammations of other membranes do to that of the parenchyma, or substantial parts of the viscus, which they surround. It affects elderly people, and frequently occasions their death; and exists at the end of the true peripneumony, or along with it; when the lancet has not been used sufficiently to cure by reabsorbing the inflamed parts, or what is termed by resolution. M. M. Diluents, mucilage, antimonials, warmish air constantly changed, venesection once, perhaps twice, if the pulse will bear it. Oily volatile draughts. Balsams? Neutral salts increase the tendency to cough. Blisters in succession about the chest. Warm bath. Mild purgatives. Very weak chicken broth without salt in it. Boiled onions. One grain of calomel every night for a week. From five drops to ten of tincture of opium at six every night, when the patient becomes weak. Digitalis? See Class II. 1. 6. 7. 8. _Pertussis._ Tussis convulsiva. Chin-cough resembles peripneumonia superficialis in its consisting in an inflammation of the membrane which lines the air-vessels of the lungs; but differs in the circumstance of its being contagious; and is on that account of very long duration; as the whole of the lungs are probably not infected at the same time, but the contagious inflammation continues gradually to creep on the membrane. It may in this respect be compared to the ulcers in the pulmonary consumption; but it differs in this, that in chin-cough some branches of the bronchia heal, as others become inflamed. This complaint is not usually classed amongst febrile disorders, but a sensitive fever may generally be perceived to attend it during some part of the day, especially in weak patients. And a peripneumony very frequently supervenes, and destroys great numbers of children, except the lancet or four or six leeches be immediately and repeatedly used. When the child has permanent difficulty of breathing, which continues between the coughing fits: unless blood be taken from it, it dies in two, three, or four days of the inflammation of the lungs. During this permanent difficulty of breathing the hooping-cough abates, or quite ceases, and returns again after once or twice bleeding; which is then a good symptom, as the child now possessing the power to cough shews the difficulty of breathing to be abated. I dwell longer upon this, because many lose their lives from the difficulty there is in bleeding young children; where the apothecary is old or clumsy, or is not furnished with a very sharp and fine-pointed lancet. In this distressing situation the application of four leeches to one of the child's legs, the wounds made by which should continue to bleed an hour or two, is a succedaneum; and saves the patient, if repeated once or twice according to the difficulty of the respiration. The chin-cough seems to resemble the gonorrhoea venerea in several circumstances. They are both received by infection, are both diseases of the mucous membrane, are both generally cured in four or six weeks without medicine. If ulcers in the cellular membrane under the mucous membrane occur, they are of a phagedenic kind, and destroy the patient in both diseases, if no medicine be administered. Hence the cure should be similar in both these diseases; first general evacuations and diluents, then, after a week or two, I have believed the following pills of great advantage. The dose for a child of about three years old was one sixth part of a grain of calomel, one sixth part of a grain of opium, and two grains of rhubarb, to be taken twice a day. The opium promotes absorption from the mucous membrane, and hence contributes to heal it. The mercury prevents ulcers from being formed under the mucous membrane, or cures them, as in the lues venerea; and the rhubarb is necessary to keep the bowels open. M. M. Antimonial vomits frequently repeated. Mild cathartics. Cool air. Tincture of cantharides, or repeated blisters; afterwards opiates in small doses, and the bark. Warm bath frequently used. The steam of warm water with a little vinegar in it may be inhaled twice a day. Could the breathing of carbonic acid gas mixed with atmospheric air be of service? Copious venesection, when a difficulty of breathing continues between the fits of coughing; otherwise the cough and the expectoration cease, and the patient is destroyed. Ulcers of the lungs sometimes supervene, and the phthisis pulmonalis in a few weeks terminates in death. Where the cough continues after some weeks without much of the hooping, and a sensitive fever daily supervenes, so as to resemble hectic fever from ulcers of the lungs; change of air for a week or fortnight acts as a charm, and restores the patient beyond the hopes of the physician. Young children should lie with their heads and shoulders raised; and should be constantly watched day and night; that when the cough occurs, they may be held up easily, so as to stand upon their feet bending a little forwards; or nicely supported in that posture which they seem to put themselves into. A bow of whalebone, about the size of the bow of a key, is very useful to extract the phlegm out of the mouths of infants at the time of their coughing; as an handkerchief, if applied at the time of their quick inspirations after long holding their breath, is dangerous, and may suffocate the patient in an instant, as I believe has sometimes happened. 9. _Variola discreta._ The small-pox is well divided by Sydenham into distinct and confluent. The former consists of distinct pustules, which appear on the fourth day of the fever, are circumscribed and turgid; the fever ceasing when the eruption is complete. Head-ach, pain in the loins, vomiting frequently, and convulsive fits sometimes, precede the eruption. The distinct small-pox is attended with sensitive fever only, when very mild, as in most inoculated patients; or with sensitive irritated fever, when the disease is greater: the danger in this kind of small-pox is owing either to the tumor and soreness of the throat about the height, or eighth day of the eruption; or to the violence of the secondary fever. For, first, as the natural disease is generally taken by particles of the dust of the contagious matter dried and floating in the air, these are liable to be arrested by the mucus about the throat and tonsils in their passage to the lungs, or to the stomach, when they are previously mixed with saliva in the mouth. Hence the throat inflames like the arm in inoculated patients; and this increasing, as the disease advances, destroys the patient about the height. Secondly, all those upon the face and head come out about the same time, namely, about one day before those on the hands, and two before those in the trunk; and thence, when the head is very full, a danger arises from the secondary fever, which is a purulent, not a variolous fever; for as the matter from all these of the face and head is reabsorbed at the same time, the patient is destroyed by the violence of this purulent fever; which in the distinct small-pox can only be abated by venesection and cathartics; but in the confluent small-pox requires cordials and opiates, as it is attended with arterial debility. See Sect. XXXV. 1. and XXXIII. 2. 10. When the pustules on the face recede, the face swells; and when those of the hands recede, the hands swell; and the same of the feet in succession. These swellings seem to be owing to the absorption of variolous matter, which by its stimulus excites the cutaneous vessels to secrete more lymph, or serum, or mucus, exactly as happens by the stimulus of a blister. Now, as a blister sometimes produces strangury many hours after it has risen; it is plain, that a part of the cantharides is absorbed, and carried to the neck of the bladder; whether it enters the circulation, or is carried thither by retrograde movements of the urinary branch of lymphatics; and by parity of reasoning the variolous matter is absorbed, and swells the face and hands by its stimulus. _Variola confluens._ The confluent small-pox consists of numerous pustules, which appear on the third day of the fever, flow together, are irregularly circumscribed, flaccid, and little elevated; the fever continuing after the eruption is complete; convulsions do not precede this kind of small-pox, and are so far to be esteemed a favourable symptom. The confluent small-pox is attended with sensitive inirritated fever, or inflammation with arterial debility; whence the danger of this disease is owing to the general tendency to gangrene, with petechiæ, or purple spots, and hæmorrhages; besides the two sources of danger from the tumor of the throat about the height, or eleventh day of the eruption, and the purulent fever after that time; which are generally much more to be dreaded in this than in the distinct small-pox described above. M. M. The method of treatment must vary with the degree and kind of fever. Venesection may be used in the distinct small-pox early in the disease, according to the strength or hardness of the pulse; and perhaps on the first day of the confluent small-pox, and even of the plague, before the sensorial power is exhausted by the violence of the arterial action? Cold air, and even washing or bathing in cold water, is a powerful means in perhaps all eruptive diseases attended with fever; as the quantity of eruption depends on the quantity of the fever, and the activity of the cutaneous vessels; which may be judged of by the heat produced on the skin; and which latter is immediately abated by exposure to external cold. Mercurial purges, as three grains of calomel repeated every day during the eruptive fever, so as to induce three or four stools, contribute to abate inflammation; and is believed by some to have a specific effect on the variolous, as it is supposed to have on the venereal contagion. It has been said, that opening the pock and taking out the matter has not abated the secondary fever; but as I had conceived, that the pits, or marks left after the small-pox, were owing to the acrimony of the matter beneath the hard scabs, which not being able to exhale eroded the skin, and produced ulcers, I directed the faces of two patients in the confluent small-pox to be covered with cerate early in the disease, which was daily renewed; and I was induced to think, that they had much less of the secondary fever, and were so little marked, that one of them, who was a young lady, almost entirely preserved her beauty. Perhaps mercurial plasters, or cerates, made without turpentine in them, might have been more efficacious, in preventing the marks, and especially if applied early in the disease, even on the first day of the eruption, and renewed daily. For it appears from the experiments of Van Woensel, that calomel or sublimate corrosive, triturated with variolous matter, incapacitates it from giving the disease by inoculation. Calomel or sublimate given as an alterative for ten days before inoculation, and till the eruptive fever commences, is said with certainty to render the disease mild by the same author. Exper. on Mercury by Van Woensel, translated by Dr. Fowle, Salisbury. _Variola inoculata._ The world is much indebted to the great discoverer of the good effects of inoculation, whose name is unknown; and our own country to Lady Wortley Montague for its introduction into this part of Europe. By inserting the variolous contagion into the arm, it is not received by the tonsils, as generally happens, I suppose, in the natural small-pox; whence there is no dangerous swelling of the throat, and as the pustules are generally few and distinct, there is seldom any secondary fever; whence those two sources of danger are precluded; hence when the throat in inoculated small-pox is much inflamed and swelled, there is reason to believe, that the disease had been previously taken by the tonsils in the natural way.--Which also, I suppose, has generally happened, where the confluent kind of small-pox has occurred on inoculation. I have known two instances, and have heard of others, where the natural small-pox began fourteen days after the contagion had been received; one of these instances was of a countryman, who went to a market town many miles from his home, where he saw a person in the small-pox, and on returning the fever commenced that day fortnight: the other was of a child, whom the ignorant mother carried to another child ill of the small-pox, on purpose to communicate the disease to it; and the variolous fever began on the fourteenth day from that time. So that in both these cases fever commenced in half a lunation after the contagion was received. In the inoculated small-pox the fever generally commences on the seventh day, or after a quarter of a lunation; and on this circumstance probably depends the greater mildness of the latter. The reason of which is difficult to comprehend; but supposing the facts to be generally as above related, the slower progress of the contagion indicates a greater inirritability of the system, and in consequence a tendency to malignant rather than to inflammatory fever. This difference of the time between the reception of the infection and the fever in the natural and artificial small-pox may nevertheless depend on its being inserted into a different series of vessels; or to some unknown effect of lunar periods. It is a subject of great curiosity, and deserves further investigation. When the inoculated small-pox is given under all the most favourable circumstances I believe less than one in a thousand miscarry, which may be ascribed to some unavoidable accident, such as the patient having previously received the infection, or being about to be ill of some other disease. Those which have lately miscarried under inoculation, as far as has come to my knowledge, have been chiefly children at the breast; for in these the habit of living in the air has been confirmed by so short a time, that it is much easier destroyed, than when these habits of life have been established by more frequent repetition. See Sect. XVII. 3. Thus it appears from the bills of mortality kept in the great cities of London, Paris, and Vienna, that out of every thousand children above three hundred and fifty die under two years old. (Kirkpatrick on Inoculation.) Whence a strong reason against our hazarding inoculation before that age is passed, especially in crowded towns; except where the vicinity of the natural contagion renders it necessary, or the convenience of inoculating a whole family at a time; as it then becomes better to venture the less favourable circumstances of the age of the patient, or the chance of the pain from toothing, than to risk the infection in the natural way. The most favourable method consists in, first, for a week before inoculation, restraining the patients from all kinds of fermented or spirituous liquor, and from animal food; and by giving them from one grain to three or four of calomel every other day for three times. But if the patients be in any the least danger of taking the natural infection, the inoculation had better be immediately performed, and this abstinence then began; and two or three gentle purges with calomel should be given, one immediately, and on alternate days. These cathartics should not induce more than two or three stools. I have seen two instances of a confluent small-pox in inoculation following a violent purging induced by too large a dose of calomel. Secondly, the matter used for inoculation should be in a small quantity, and warm, and fluid. Hence it is best when it can be recently taken from a patient in the disease; or otherwise it may be diluted with part of a drop of warm water, since its fluidity is likely to occasion its immediate absorption; and the wound should be made as small and superficial as possible, as otherwise ulcers have been supposed sometimes to ensue with subaxillary abscesses. Add to this, that the making two punctures either on the same, or one on each arm, secures the success of the operation in respect to communicating the infection. Thirdly, at the time of the fever or eruption the application of cool air to those parts of the skin, which are too warm, or appear red, or are covered with what is termed a rash, should be used freely, as well as during the whole disease. And at the same time, if the feet or hands are colder than natural, these should be covered with flannel. See Class IV. 2. 2. 10. 10. _Rubeola irritata, morbilli._ The measles commence with sneezing, red eyes, dry hoarse cough, and is attended with sensitive irritated fever. On the fourth day, or a little later, small thick eruptions appear, scarcely eminent above the skin, and, after three days, changing into very small branny scales. As the contagious material of the small-pox may be supposed to be diffused in the air like a fine dry powder, and mixing with the saliva in the mouth to infect the tonsils in its passage to the stomach; so the contagious material of the measles may be supposed to be more completely dissolved in the air, and thus to impart its poison to the membrane of the nostrils, which covers the sense of smell; whence a catarrh with sneezing ushers in the fever; the termination of the nasal duct of the lacrymal sac is subject to the same stimulus and inflammation, and affects by sympathy the lacrymal glands, occasioning a great flow of tears. See Sect. XVI. 8. And the redness of the eye and eyelids is produced in consequence of the tears being in so great quantity, that the saline part of them is not entirely reabsorbed. See Sect. XXIV. 2. 8. The contagion of the measles, if it be taken a sufficient time before inoculation, so that the eruption may commence before the variolous fever comes on, stops the progress of the small-pox in the inoculated wound, and delays it till the measle-fever has finished its career. See Sect. XXXIII. 2. 9. The measles are usually attended with inflammatory fever with strong pulse, and bear the lancet in every stage of the disease. In the early periods of it, venesection renders the fever and cough less; and, if any symptoms of peripneumony occur, is repeatedly necessary; and at the decline of the disease, if a cough be left after the eruption has ceased, and the subsequent branny scales are falling off, venesection should be immediately used; which prevents the danger of consumption. At this time also change of air is of material consequence, and often removes the cough like a charm, as mentioned in a similar situation at the end of the chin-cough. _Rubeola inirritata._ Measles with inirritated fever, or with weak pulse, has been spoken of by some writers. See London Med. Observ. Vol. IV. Art. XI. It has also been said to have been attended with sore throat. Edinb. Essays, Vol. V. Art. II. Could the scarlet fever have been mistaken for the measles? or might one of them have succeeded the other, as in the measles and small-pox mentioned in Sect. XXXIII. 2. 9.? From what has been said, it is probable that inoculation might disarm the measles as much as the small-pox, by preventing the catarrh, and frequent pulmonary inflammation, which attends this disease; both of which are probably the consequence of the immediate application of the contagious miasmata to these membranes. Some attempts have been made, but a difficulty seems to arise in giving the disease; the blood, I conjecture, would not infect, nor the tears; perhaps the mucous discharge from the nostrils might succeed; or a drop of warm water put on the eruptions, and scraped off again with the edge of a lancet; or if the branny scales were collected, and moistened with a little warm water? Further experiments on this subject would be worthy the public attention. 11. _Scarlatina mitis._ The scarlet fever exists with all degrees of virulence, from a flea-bite to the plague. The infectious material of this disease, like that of the small-pox, I suppose to be diffused, not dissolved, in the air; on which account I suspect, that it requires a much nearer approach to the sick, for a well person to receive the infection, than in the measles; the contagion of which I believe to be more volatile, or diffusible in the atmosphere. But as the contagious miasmata of small-pox and scarlet fever are supposed to be more fixed, they may remain for a longer time in clothes or furniture; as a thread dipped in variolous matter has given the disease by inoculation after having been exposed many days to the air, and after having been kept many months in a phial. This also accounts for the slow or sporadic progress of the scarlet fever, as it infects others at but a very small distance from the sick; and does not produce a quantity of pus-like matter, like the small-pox, which can adhere to the clothes of the attendants, and when dried is liable to be shook off in the form of powder, and thus propagate the infection. This contagious powder of the small-pox, and of the scarlet fever, becomes mixed with saliva in the mouth, and is thus carried to the tonsils, the mucus of which arrests some particles of this deleterious material; while other parts of it are carried into the stomach, and are probably decomposed by the power of digestion; as seems to happen to the venom of the viper, when taken into the stomach. Our perception of bad tastes in our mouths, at the same time that we perceive disagreeable odours to our nostrils, when we inhale very bad air, occasions us to spit out our saliva; and thus, in some instances, to preserve ourselves from infection. This has been supposed to originate from the sympathy between the organs of taste and smell; but any one who goes into a sick room close shut up, or into a crowded assembly-room, or tea-room, which is not sufficiently ventilated, may easily mix the bad air with the saliva on his tongue so as to taste it; as I have myself frequently attended to. Hence it appears that these heavy infectious matters are more liable to mix with the saliva, and inflame the tonsils, and that either before or at the commencement of the fever; and this is what generally happens in the scarlet fever, always I suppose in the malignant kind, and very frequently in the mild kind. But as this infection may be taken by other means, as by the skin, it also happens in the most mild kind, that there is no inflammation of the tonsils at all; in the same manner as there is generally no inflammation of the tonsils in the inoculated small-pox. In the mild scarlatina on the fourth day of the fever the face swells a little, at the same time a florid redness appears on various parts of the skin, in large blotches, at length coalescing, and after three days changing into branny scales. M. M. Cool air. Fruit. Lemonade. Milk and water. _Scarlatina maligna._ The malignant scarlet fever begins with inflamed tonsils; which are succeeded by dark drab coloured sloughs three or five lines in diameter, flat, or beneath the surrounding surface; and which conceal beneath them spreading gangrenous ulcers. The swellings of the tonsils are sensible to the eye and touch externally, and have an elastic rather than an oedematous feel, like parts in the vicinity of gangrenes. The pulse is very quick and weak, with delirium, and the patient generally dies in a few days; or if he recovers, it is by slow degrees, and attended with anasarca. M. M. A vomit once. Wine. Beer. Cyder. Opium. Bark; in small repeated doses. Small successive blisters, if the extremities are cooler than natural. Cool air on the hot parts of the skin, the cool extremities being at the same time covered. Iced lemonade. Broth. Custards. Milk. Jellies. Bread pudding. Chicken. Touch the ulcers with a dry sponge to absorb the contagious matter, and then with a sponge filled with vinegar, with or without sugar of lead dissolved in it, about six grains to an ounce; or with a very little blue vitriol dissolved in it, as a grain to an ounce; but nothing so instantaneously corrects the putrid smell of ulcers as a solution of alum; about half an ounce to a pint of water, which should be a little warmish, and injected into the fauces gently by means of a syringe. These should be repeated frequently in a day, if it can be done easily, and without fatigue to the child. A little powder of bark taken frequently into the mouth, as a grain or two, that it may mix with the saliva, and thus frequently stimulate the dying tonsils. Could a warm bath made of decoction of bark, or a cold fomentation with it, be of service? Could oxygene gas mixed with common air stimulate the languid system? Small electric shocks through the tonsils every hour? ether frequently applied externally to the swelled tonsils? As this disease is attended with the greatest degree of debility, and as stimulant medicines, if given in quantity, so as to produce more than natural warmth, contribute to expend the already too much exhausted sensorial power; it appears, that there is nothing so necessary to be nicely attended to, as to prevent any unnecessary motions of the system; this is best accomplished by the application of cold to those parts of the skin, which are in the least too hot. And secondly, that the exhibition of the bark in such quantity, as not to oppress the stomach and injure digestion, is next to be attended to, as not being liable to increase the actions of the system beyond their natural quantity; and that opium and wine should be given with the greatest caution, in very small repeated quantity, and so managed as to prevent, if possible, the cold fits of fever; which probably occur twice in 25 hours, obeying the lunations like the tides, as mentioned in Sect. XXXII. 6. that is, I suppose, the cold periods, and consequent exacerbations of fever, in this malignant scarlatina, occur twice in a lunar day; which is about ten minutes less than 25 hours; so that if the commencement of one cold fit be marked, the commencement of the next may be expected, if not disturbed by the exhibition of wine or opium, or the application of blisters, to occur in about twelve hours and a half from the commencement of the former; or if not prevented by large doses of the bark. No one could do an act more beneficial to society, or glorious to himself, than by teaching mankind how to inoculate this fatal disease; and thus to deprive it of its malignity. Matter might be taken from the ulcers in the throat, which would probably convey the contagion. Or warm water might be put on the eruption, and scraped off again by the edge of a lancet. These experiments could be attended with no danger, and should be tried for the public benefit, and the honour of medical science. 12. _Miliaria._ Miliary fever. An eruption produced by the warmth, and more particularly by the stimulus of the points of the wool in flannel or blankets applied to the skin, has been frequently observed; which, by cool dress, and bed-clothes without flannel, has soon ceased. See Class I. 1. 2. 3. This, which maybe called _miliaria sudatoria_, has been confounded with other miliary fevers, and has made the existence of the latter doubted. Two kinds of eruptions I have seen formerly attended with fever, but did not sufficiently mark their progress, which I conceived to be miliary eruptions, one with arterial strength, or with sensitive irritated fever, and the other with arterial debility, or with sensitive inirritated fever. In the former of these, or _miliaria irritata_, the eruptions were distinct and larger than the small-pox, and the fever was not subdued without two or three venesections, and repeated cathartics with calomel. The latter, or _miliaria inirritata_, was attended with great arterial debility; and during the course of the fever pellucid points appeared within the skin, particularly on the soft parts of the fingers. And, in one patient, whom I esteemed near her end, I well recollect to have observed round pellucid globules, like what are often seen on vines in hot-houses, no larger than the smallest pins' heads, adhere to her neck and bosom; which were hard to the touch, but were easily rubbed off. These diseases, if they are allied, do not differ more than the kinds of small-pox; but require many further observations. The eruption so often seen on children in the cradle, and called by the nurses red-gum, and which is attended with some degree of fever, I suspect to be produced by too great warmth, and the contact of flannel next their tender skins, like the miliaria sudatoria; and like that requires cool air, cool clothes, and linen next their skin. 13. _Pestis._ The plague, like other diseases of this class, seems to be sometimes mild, and sometimes malignant; according to the testimony of different writers. It is said to be attended with inflammation, with the greatest arterial debility, and to be very contagious, attended at an uncertain time of the fever with buboes and carbuncles. Some authors affirm, that the contagion of the plague may be repeatedly received, so as to produce the disease; but as this is contrary to the general analogy of all contagious diseases, which are attended with fever, and which cure themselves spontaneously; there is reason to suspect, that where it has been supposed to have been repeatedly received, that some other fever with arterial debility has been mistaken for it, as has probably universally been the case, when the small-pox has been said to have been twice experienced. M. M. Venesection has been recommended by some writers on the first day, where the inflammation was supposed to be attended with sufficient arterial strength, which might perhaps sometimes happen, as the bubo seems to be a suppuration; but the carbuncle, or anthrax, is a gangrene of the part, and shews the greatest debility of circulation. Whence all the means before enumerated in this genus of diseases to support the powers of life are to be administered. Currents of cold air, cold water, ice, externally on the hot parts of the skin. The methods of preventing the spreading of this disease have been much canvassed, and seem to consist in preventing all congregations of the people, as in churches, or play-houses; and to remove the sick into tents on some airy common by the side of a river, and supply them with fresh food, both animal and vegetable, with beer and wine in proper quantities, and to encourage those who can, daily to wash both their clothes and themselves. The _pestis vaccina_, or disease amongst the cows, which afflicted this island about half a century ago, seems to have been a contagious fever with great arterial debility; as in some of them in the latter stage of the disease, an emphysema could often be felt in some parts, which evinced a considerable progress of gangrene beneath the skin. In the sensitive inirritated fevers of these animals, I suppose about sixty grains of opium, with two ounces of extract of oak-bark, every six hours, would supply them with an efficacious medicine; to which might be added thirty grains of vitriol of iron, if any tendency to bloody urine should appear, to which this animal is liable. The method of preventing the infection from spreading, if it should ever again gain access to this island, would be immediately to obtain an order from government to prevent any cattle from being removed, which were found within five miles of the place supposed to be infected, for a few days; till the certainty of the existence of the pestilence could be ascertained, by a committee of medical people. As soon as this was ascertained, all the cattle within five miles of the place should be immediately slaughtered, and consumed within the circumscribed district; and their hides put into lime-water before proper inspectors. 14. _Pemphigus_ is a contagious disease attended with bladdery eruptions appearing on the second or third day, as large as filberts, which, remain many days, and then effuse a thin ichor. It seems to be either of a mild kind with sensitive fever only, of which I have seen two instances, or with irritated, or with inirritated fever, as appears from the observations of M. Salabert. See Medical Comment, by Dr. Duncan, Decad. II. Vol. VI. 15. _Varicella._ Chicken-pox is accompanied with sensitive fever, pustules break out after a mild fever like the small-pox, seldom suppurate, and generally terminate in scales without scars. I once saw a lady, who miscarryed during this disease, though all her children had it as slightly as usual. It sometimes leaves scars or marks on the skin. This disease has been mistaken for the small-pox, and inoculated for it; and then the small-pox has been supposed to happen twice to the same person. See Trans. of the College London. It is probable that the pemphigus and urticaria, as well as this disease, have formerly been diseases of more danger; which the habit of innumerable generations may have rendered mild, and will in process of time annihilate. In the same manner as the small-pox, venereal disease, and rickets, seem to become milder or less in quantity every half century. While at the same time it is not improbable, that other new diseases may arise, and for a season thin mankind! 16. _Urticaria._ Nettle-rash begins with mild sensitive fever, which is sometimes scarcely perceptible. Hence this eruption has been thought of two sorts, one with and the other without fever. On the second day red spots, like parts stung with nettles, are seen; which almost vanish during the day, and recur in the evening with the fever, succeeded in a few days by very minute scales. See Trans. of the College, London. 17. _Aphtha._ Thrush. It has been doubted, whether aphtha or thrush, which consists of ulcers in the mouth, should be enumerated amongst febrile diseases; and whether these ulcers are always symptomatic, or the consequence rather than the cause of the fevers which attend them. The tongue becomes rather swelled; its colour and that of the fauces purplish; sloughs or ulcers appear first on the throat and edges of the tongue, and at length over the whole mouth. These sloughs are whitish, sometimes distinct, often coalescing, and remain an uncertain time. Cullen. I shall concisely mention four cases of aphtha, but do not pretend to determine whether they were all of them symptomatic or original diseases. _Aphtha sensitiva._ A lady during pregnancy was frequently seized with ulcers on her tongue and cheeks, or other parts of the mouth, without much apparent fever; which continued two or three weeks, and returned almost every month. The thrush in the mouths of young children seems to be a similar disease. These ulcers resemble those produced in the sea-scurvy, and have probably for their cause an increased action of the secerning system from increased sensation, with a decreased action of the absorbent system from decreased irritation. See Class I. 2. 1. 15. M. M. Solutions of alum, of blue vitriol. Powder of bark taken frequently into the mouth in very small quantity. See Class II. 1. 3. 1. _Aphtha irritata._ Inflammatory aphtha. A case of this kind is related under the title of suppurative rheumatism. Class IV. 1. 2. 16. _Aphtha inirritata._ Sloughs or ulcers of the mouth, attended with sensitive fever with great arterial debility. They seem to spread downwards from the throat into the stomach, and probably through the whole intestinal canal, beginning their course with cardialgia, and terminating it with tenesmus; and might perhaps be called an erysipelas of this mucous membrane. M. M. Cool air. A small blister on the back. Bark. Wine. Opium in small repeated quantities. Soap neutralizes the gastric acid without effervescence, and thus relieves the pain of cardialgia, where the stomach is affected. Milk also destroys a part of this acid. Infusion of sage leaves two ounces, almond soap from five grains to ten, with sugar and cream, is generally both agreeable and useful to these patients. See I. 2. 4. 5. Where the stomach may be supposed to be excoriated by poisons containing acid, as sublimate of mercury or arsenic; or if it be otherwise inflamed, or very sensible to the stimulus of the gastric acid; or where it abounds with acid of any kind, as in cardialgia; the exhibition of soap is perhaps a preferable manner of giving alcali than any other, as it decomposes in the stomach without effervescence; while the caustic alcali is too acrid to be administered in such cases, and the mild alcali produces carbonic gas. If a drop of acid of vitriol be put on cap paper, it will be long before it destroys the paper; but if a drop of mild alcali be added, a sudden effervescence arises, and the paper is instantly destroyed by the escape of the fixed air; in the same manner as lumps of solid lime are broken into powder by the escape of the steam produced from the water, which is poured on them. This shews why a succession of acid and of alcaline caustics sooner destroys a part, than either of them applied separately. 18. _Dysenteria._ Bloody-flux is attended with sensitive fever generally with arterial debility; with frequent mucous or bloody stools; which contain contagious matter produced by the membranes of the intestines; the alimentary excrement being nevertheless retained; with griping pains and tenesmus. M. M. Emetics. Antimonials. Peruvian bark. Opium and calomel of each a grain every night. Bolus armeniæ. Earth of alum. Chalk. Calcined hartshorn. Mucilage. Bee's wax mixt with yolk of egg. Cerated glass of antimony. Warm bath. Flannel clothing next to the skin. Large clysters with opium. With ipecacuanha, with smoke of tobacco? Two dysenteric patients in the same ward of the infirmary at Edinburgh quarrelled, and whipped each other with horsewhips a long time, and were both much better after it, owing perhaps to the exertion of so much of the sensorial power of volition; which, like real insanity, added excitement to the whole system. The prevention of this contagion must consist principally in ventilation and cleanliness; hence the patients should be removed into cottages distant from each other, or into tents; and their fæces buried as soon as may be; or conveyed into a running stream; and themselves should be washed with cold or warm water after every evacuation. For the contagious matter consists in the mucous or purulent discharge from the membrane which lines the intestines; and not from the febrile perspiration, or breath of the patients. For the fever is only the consequence and not the cause of contagion; as appears from Genus the Fifth of this Order, where contagion exists without fever. 19. _Gastritis superficialis._ Superficial inflammation of the stomach. An erysipelatous inflammation of the stomach is mentioned by Dr. Cullen from his own observations; which is distinguished from the inflammatory gastritis by less pain, and fever, and by an erysipelatous redness about the fauces. Does this disease belong to aphtha? 20. _Enteritis superficialis._ Superficial inflammation of the bowels is also mentioned by Dr. Cullen from his own observation under the name of enteritis erythematica; and is said to be attended with less pain and fever, without vomiting, and with diarrhoea. May not this disease be referred to aphtha, or to dysentery? * * * * * ORDO I. _Increased Sensation._ GENUS IV. _With the Production of new Vessels by internal Membranes or Glands, without Fever._ Where inflammation is produced in a small part, which has not great natural sensibility, the additional sensation does not produce an increased action of the arterial system; that is, the associated motions which are employed in the circulation of the blood, those for instance of the heart, arteries, glands, capillaries, and their correspondent veins, are not thrown into increased action by so small an addition of the sensorial power of sensation. But when parts, which naturally possess more sensibility, become inflamed, the quantity of the sensorial power of sensation becomes so much increased, as to affect the associated motions belonging to the circulation, occasioning them to proceed with greater frequency; that is, a fever is induced. This is well exemplified in the internal and superficial paronychia, one of which is attended with great pain and fever, and the other with little pain and no fever. See Class II. 1. 2. 19. and II. 1. 4. 5. From hence it appears, that the sensitive fever is an accidental consequence of the topical phlegmon, or inflammation, and not a cause of it; that it is often injurious, but never salutary; and should therefore always be extinguished, as soon as may be, either by the lancet and cathartics, and diluents, and cold air, when it is of the irritated kind; or by the bark, opium, cool air, and nutrientia, when it is of the inirritated kind. SPECIES. 1. _Ophthalmia superficialis._ As the membranes, which cover the eye, are excluded from the air about one third part of the twenty-four hours; and are moistened by perpetual nictitation during the other sixteen; they may be considered as internal membranes; and from the analogy of their inflammation to that of other internal membranes, it is arranged under this genus; whilst the tonsillitis is esteemed an inflammation of an external membrane, because currents of air are perpetually passing both day and night over the fauces. The superficial ophthalmy has generally been esteemed a symptom of scrophula, when it recurs frequently in young persons; but is probably only a concomitant of that disease, as a symptom of general debility; ramifications of new red vessels, and of enlarged old ones, are spread over the white part of the eye; and it is attended with less heat, less pain, and less intolerance of light than the ophthalmia interna, described in Class II. 1. 2. 2. It occurs in those of feeble circulation, especially children of a scrophulous tendency, and seems to arise from a previous torpor of the vessels of the tunica albuginea from their being exposed to cold air; and from this torpor being more liable to occur in habits, which are naturally inirritable; and therefore more readily fall into quiescence by a smaller deduction of the stimulus of heat, than would affect stronger or more irritable habits; the consequence of this torpor is increased action, which produces pain in the eye, and that induces inflammation by the acquisition of the additional sensorial power of sensation. _Ophthalmia lymphatica_ is a kind of anasarca of the tunica adnata; in this the vessels over the sclerotica, or white part of the eye, rise considerably above the cornea, which they surround, are less red than in the ophthalmia superficialis, and appear to be swelled by an accumulation of lymph rather than of blood; it is probably owing to the temporary obstruction of a branch of the lymphatic system. M. M. If the pain be great, venesection by leeches on the temple, or cutting the temporal artery, and one purge with three or four grains of calomel should be premised. Then the Peruvian bark twice a day. Opium from a quarter to half a grain twice a day for some weeks. Bathe the eye frequently with cold water alone, or with cold water, to a pint of which is added half an ounce of salt. White vitriol six grains dissolved in one ounce of water; a drop or two to be put between the eyelids twice a day. Take very small electric sparks from the eyes every day for a fortnight. Bathe the whole head with salt and water made warm every night for some months. Send such children to a school near the sea for the convenience of sea-bathing for many months annually; such schools are to be found in or near Liverpool. When a child is afflicted with an inflamed eye of this kind, he should always sit with his back to the window or candle; but it is generally not necessary to cover it, or if the uneasy sensation of light makes this proper, the cover should stand off from the eye, so as not much to exclude the cool air from it. As covering an eye unnecessarily is liable to make that eye weaker than the other, from its not being sufficiently used, and thence to produce a squinting for ever afterwards. Nevertheless, when the pain is great, a poultice must be applied to keep the eyes moist, or a piece of oiled silk bound lightly over them. Or thus, boil an egg till it is hard, cut it longitudinally into two hemispheres, take out the yolk, sew the backs of the two hollow hemispheres of the white to a ribbon, and bind them over the eyes every night on going to bed; which, if nicely fitted on, will keep the eyes moist without any disagreeable pressure. See Class I. 1. 3. 14. _Ophthalmia equina._ An inflammation of this kind is liable to affect the eyes of horses; one cause of which is owing to a silly custom of cutting the hair out of horses' ears; by which they are not only liable to take cold at the ear, but grass seeds are liable to fall into their ears from the high racks in stables; and in both cases the eye becomes inflamed by sympathy. I once directed the temporal artery of a horse to be opened, who had frequent returns of an inflamed eye; and I believed it was of essential service to him; it is probable that the artery was afterwards contracted in the wounded part, and that thence less blood was derived to the eye: the hæmorrhage was stopped by two persons alternately keeping their fingers on the orifice, and afterwards by a long bandage of broad tape. 2. _Pterigion._ Eye-wing. A spot of inflammation sometimes begins on the inside of the lower eyelid, or on the tunica albuginea, and spreads an intertexture of red vessels from it, as from a center, which extend on the white part of the eye, and have the appearance of the wing of a fly, from whence its name. M. M. Cut the ramifications of vessels again and again with the point of a lancet close to the center of inflammation. 3. _Tarsitis palpebrarum._ Inflammation of the edges of the eyelids. This is a disease of the glands, which produce the hairs of the eye-lashes, and is frequently the cause of their falling off. After this inflammation a hard scar-like ridge is left on the edge of the eyelid, which scratches and inflames the eyeball, and becomes a very troublesome disease. The Turkish ladies are said to colour the edge of the eyelash with crude antimony in very fine powder, which not only gives lustre to the eye, as a diamond set on a black soil, but may prevent extraneous light from being reflected from these edges into the eye, and thus serve the purpose of the black feathers about the eyes of swans, described in Sect. XXXIX. 5. 1. and may also prevent the edges of the eyelids from being inflamed by the frequent stimulus of tears on them. Black lead in fine powder might be better for all these purposes than antimony, and might be put on with a camel's hair brush. M. M. Mercurial ointment smeared at night on the edges of the eyelids. Burnt alum sixty grains, hog's grease half an ounce, well rubbed into an ointment to be smeared on them in the night. Cold water frequently in the day. See Class II. 1. 1. 8. 4. _Hordeolum._ Stye. This inflammation begins either on or near the edges of the eyelids, or in the loose skin of them, and is sometimes very slow either in coming to suppuration or in dispersing. The skin beneath the lower eyelid is the most frequent seat of this tumor, which sometimes never suppurates at all, but becomes an incysted tumor: for as this skin is very loose for the purpose of admitting great motion to the eyelid, the absorbent power of the veins seems particularly weak in this part; whence when any person is weakened by fatigue or otherwise, a darker shade of colour is seen beneath the eyes; which is owing to a less energetic action of the absorbent terminations of the veins, whence the currents of dark or venous blood are delayed in them. This dark shade beneath the eyes, when it is permanent, is a symptom of habitual debility, or inirritability of the circulating system. See Class I. 2. 2. 2. M. M. Smear the tumors with mercurial ointment, moisten them frequently with ether. To promote their suppuration they may be wounded with a lancet, or slit down the middle, or they may be cut out. A caustic leaves a large scar. 5. _Paronychia superficialis._ Whitlow. An inflammation about the roots of the nail beneath the skin, which suppurates without fever, and sometimes destroys the nail; which is however gradually reproduced. This kind of abscess, though not itself dangerous, has given opportunity for the inoculation of venereal matter in the hands of accoucheurs, and of putrid matter from the dissection of diseased bodies; and has thus been the cause of disease and death. When putrid matter has been thus absorbed from a dead body, a livid line from the finger to the swelled gland in the axilla is said to be visible; which shews the inflammation of the absorbent vessel along its whole course to the lymphatic gland; and death has generally been the consequence. M. M. In the common paronychia a poultice is generally sufficient. In the absorption of putrid matter rub the whole hand and arm with mercurial ointment three or four times a day, or perpetually. Could the swelled axillary gland be exsected? In the absorption of venereal matter the usual methods of cure in syphilis must be administered, as in Class II. 1. 5. 2. 6. _Gutta rosea._ The rosy drop on the face is of three kinds. First, the _gutta rosea hepatica_, or the red pimples on the faces of drunkards, which are probably a kind of crisis, or vicarious inflammation, which succeeds, or prevents, a torpor of the membranes of the liver. This and the succeeding species properly belong to Class IV. 1. 2. 14. Secondly, the pimpled face in consequence of drinking cold water, or eating cold turnips, or other insipid food, when much heated with exercise; which probably arises from the sympathy between the skin of the face and the stomach; and may be called the _gutta rosea stomatica_. Which is distinguished from the former by the habits of the patient in respect to drinking; by the colour of the eruptions being less deep; and by the patient continuing generally to be troubled with some degree of apepsia. See Class I. 3. 1. 3. I knew a lady, who had long been afflicted with pain about the region of the stomach; and, on drinking half a pint of vinegar, as a medicine, she had a breaking out commenced on her face; which remained, and she became free from the pain about the stomach. Was this a stomachic, or an hepatic disease? Thirdly, there is a red face, which consists of smaller pimples than those above mentioned; and which is less liable to suppurate; and which seems to be hereditary, or at least has no apparent cause like those above mentioned; which may be termed _gutta rosea hereditaria_, or puncta rosea. Mrs. S. had a pimpled face, which I believe arose from potation of ale. She applied alum in a poultice to it, and had soon a paralytic stroke, which disabled her on one side, and terminated in her death. Mrs. L. had a red pimpled face, which seemed to have been derived from her mother, who had probably acquired it by vinous potation; she applied a quack remedy to it, which I believe was a solution of lead, and was seized with epileptic fits, which terminated in palsy, and destroyed her. This shews the danger of using white paint on the face, which is called bismuth, but is in reality white lead or cerussa. Mr. Y---- had acquired the gutta rosea on his nose, and applied a saturnine solution on it for a few nights, and was then seized with paralysis on one side of his face; which however he gradually recovered, and has since acquired the gutta rosea on other parts of his face. These fatal effects were probably caused by the disagreeable sensation of an inflamed liver, which used before to be relieved of the sympathetic action and consequent inflammation of the skin of the face, which was now prevented by the stronger stimulus of the application of calx of lead. The manner in which disagreeable sensations induce epilepsy and palsy is treated of in Class III. In some cases where habitual discharges, or eruptions, or ulcers are stopped, a torpor of the system may follow, owing to the want of the accustomed quantity of sensation or irritation. See Class I. 1. 2. 9. and II. 1. 5. 6. In both these situations some other stimulus should be used to supply the place of that which is taken away; which may either be perpetual, as an issue; or periodical, as a cathartic repeated once a fortnight or month. Miss W. an elegant young lady of about twenty, applied a mercurial lotion to her face, which was covered with very small red points; which seemed to have been not acquired by any known or avoidable means; she was seized with inflammation of her liver, and after repeated bleeding and cathartics recovered, and in a few weeks the eruption appeared as before. M. M. Five grains of calomel once a month, with a cathartic, five grains of rhubarb and a quarter of a grain of emetic tartar every night for many weeks. With this preparation mercurial plasters, made without turpentine, and applied every night, and taken off every morning, will sometimes succeed, and may be used with safety. But blistering the face all over the eruption, beginning with a part, succeeds better than any other means, as I have more than once experienced.--Something like this is mentioned in the Letters of Lady Mary Wortley Montague, who blistered her face with balsam of Mecca. Mrs. F. had for many years had a disagreeably looking eruption on her chin, after a cathartic with calomel, she was advised to blister her whole chin; on the healing of the blister a few eruptions again appeared, which ceased on the application of a second blister. She took rhubarb five grains, and emetic tartar a quarter of a grain every night for many weeks. Miss L. a young lady about eighteen, had tried variety of advice for pimples over the greatest part of her face in vain. She took the above medicines internally, and blistered her face by degrees all over and became quite beautiful. A spot or two now and then appeared, and on this account she frequently slept with parts of her face covered with mercurial plaster, made without turpentine, which was held on by a pasteboard mask, and taken off in the mornings; if any part of the plaster adhered, a little butter or oil destroyed the adhesion. 7. _Odontitis._ Inflammatory tooth-ach is occasioned by inflammation of the membranes of the tooth, or a caries of the bone itself. The gum sometimes suppurates, otherwise a swelling of the cheek succeeds by association, and thus the violence of the pain in the membranes of the tooth is relieved, and frequently cured; and when this happens the disease properly belongs to Class IV. as it so far resembles the translations of morbid actions in the gout and rheumatism. At other times the tooth dies without caries, especially in people about sixty years of age, or before; and then it stimulates its involving membrane, like any other extraneous substance. The membrane then becomes inflamed and thickened, occasioning some pain, and the tooth rises upwards above the rest, and is gradually pushed out whole and undecayed; on its rising up a pus-like mucus is seen discharged from the gum, which surrounds it; and the gum seems to have left the tooth, as the fangs or roots of it are in part naked. M. M. Where the tooth is sound it can only be saved by evacuations by venesection, and a cathartic; and after its operation two grains of opium, a blister may also be used behind the ear, and ether applied to the cheek externally. In slighter cases two grains of opium with or without as much camphor may be held in the mouth, and suffered to dissolve near the affected tooth, and be gradually swallowed. See Class I. 2. 4. 12. Odontalgia may be distinguished from otitis by the application of cold water to the affected tooth; for as the pain of common tooth-ach is owing to torpor, whatever decreases stimulus adds to the torpor and consequent pain; whereas the pain of an inflamed tooth being ceased by the increased action of the membranes of it is in some measure alleviated by the application of cold. 8. _Otitis._ Inflammation and consequent suppuration of some membranes of the internal ear frequently occur in children, who sleep in cold rooms, or near a cold wall, without a night-cap. If the bones are affected, they come out in a long process of time, and the child remains deaf of that ear. But in this case there is generally a fever attends this inflammation; and it then belongs to another genus. M. M. A warmer night-cap. Warmish water should be gently syringed into the ear to keep it clean twice a day; and if it does not heal in a week, a little spirit of wine should be added; first about a fourth part, and it should be gradually increased to half rectified spirit and half water: if it continues long to discharge matter with a very putrid smell, the bones are injured, and will in time find their exit, during which time the ear should be kept clean by filling it with a weaker mixture of spirit of wine and water; or a solution of alum in water; which may be poured into the ear, as the head is inclined, and shook out again by turning the head, two or three times morning and evening. See Class II. 1. 4. 10. 9. _Fistula lacrymalis._ The lacrymal sack, with its puncta lacrymalia and nasal duct, are liable to be destroyed by suppuration without fever; the tears then run over the eyelids, and inflame the edges of them, and the cheeks, by their perpetual moisture, and saline acrimony. M. M. By a nice surgical operation a new aperture is to be made from the internal corner of the eye into the nostril, and a silver tube introduced, which supplies the defect by admitting the tears to pass again into the nostril. See Melanges de Chirurgie par M. Pouteau; who thinks he has improved this operation. 10. _Fistula in ano._ A mucous discharge from the anus, called by some white piles, or matter from a suppurated pile, has been mistaken for the matter from a concealed fistula. A bit of cotton wool applied to the fundament to receive the matter, and renewed twice a day for a week or two, should always be used before examination with the probe. The probe of an unskilful empyric sometimes does more harm in the loose cellular membrane of these parts than the original ulcer, by making a fistula he did not find. The cure of a fistula in ano of those, who have been much addicted to drinking spirituous liquor, or who have a tendency to pulmonary consumption, is frequently of dangerous consequence, and is succeeded by ulcers of the lungs, and death. M. M. Ward's paste, or 20 black pepper-corns taken after each meal twice a day; the pepper-corns should be cut each into two or three pieces. The late Dr. Monro of Edinburgh asserted in his lectures, that he had known a fistula in ano cured by injecting first a mixture of rectified spirit of wine and water; and by gradually increasing the strength of it, till the patient could bear rectified spirit alone; by the daily use of which at length the sides of the fistula became callous, and ceased to discharge, though the cavity was left. A French surgeon has lately affirmed, that a wire of lead put in at the external opening of the ulcer, and brought through the rectum, and twisted together, will gradually wear itself through the gut, and thus effect a cure without much pain. The ends of the leaden wire must be twisted more and more as it becomes loose. Or, lastly, it must be laid open by the knife. 11. _Fistula urethræ._ Where a stricture of the urethra exists, from whatever cause, the patient, in forcing the stream of urine through the structure, distends the urethra behind it; which after a time is liable to burst, and to become perforated; and some of the urine is pushed into the cellular membrane, occasioning fistulas, which sometimes have large surfaces producing much matter, which is pressed out at the time of making water, and has been mistaken for a catarrh of the bladder; these fistulas sometimes acquire an external opening in the perinæum, and part of the urine is discharged that way. Can this matter be distinguished from mucus of the bladder by the criterion delivered in Class II. 1. 6. 6? M. M. The perpetual use of bougies, either of catgut or of caoutchouc. The latter may be had at No. 37, Red-lion street, Holborn, London. The former are easily made, by moistening the catgut, and keeping it stretched till dry, and then rounding one end with a pen-knife. The use of a warm bath every day for near an hour, at the heat of 94 or 96 degrees, for two or three months, I knew to be uncommonly successful in one case; the extensive fistulas completely healing. The patient should introduce a bougie always before he makes water, and endeavour to make it as slowly as possible. See Class I. 2. 3. 24. 12. _Hepatitis chronica._ Chronical inflammation of the liver. A collection of matter in the liver has frequently been found on dissection, which was not suspected in the living subject. Though there may have been no certain signs of such a collection of matter, owing to the insensibility of the internal parts of this viscus; which has thus neither been attended with pain, nor induced any fever; yet there may be in some cases reason to suspect the existence of such an abscess; either from a sense of fulness in the right hypochondre, or from transient pains sometimes felt there, or from pain on pressure, or from lying on the left side, and sometimes from a degree of sensitive fever attending it. Dr. Saunders suspects the acute hepatitis to exist in the inflammation of the hepatic artery, and the chronical one in that of the vena portarum. Treatise on the Liver. Robinson. London. 13. _Scrophula suppurans._ Suppurating scrophula. The indolent tumors of the lymphatic glands are liable, after a long time, to regain their sensibility; and then, owing to their former torpor, an increased action of the vessels, beyond what is natural, with inflammation, is the consequence of their new life, and suppuration succeeds. This cure of scrophula generally happens about puberty, when a new energy pervades the whole system, and unfolds the glands and organs of reproduction. M. M. See Class I. 2. 3. 21. Where scrophulous ulcers about the neck are difficult to heal, Dr. Beddoes was informed, in Ireland, that an empyric had had some success by inflaming them by an application of wood sorrel, oxalis acetosella, the leaves of which are bruised in a mortar, and applied on the ulcers for two or three days, and then some more lenient application is used. A poor boy, about twelve years old, had a large scrophulous ulcer on one side of the chest beneath the clavicle, and another under his jaw; he was directed, about three weeks ago, to procure a pound of dry oak-bark from the tanners, and to reduce it to fine powder, and to add to it one ounce of white lead in fine powder, and to cover the ulcers daily with it, keeping it on by brown paper and a bandage. He came to me a few minutes ago, to shew me that both the ulcers are quite healed. The constant application of linen rags, moistened with a solution of an ounce of sugar of lead in a pint of water, I think I have seen equally efficacious. 14. _Scorbutus suppurans._ In the sea-scurvy there exists an inactivity of venous absorption, whence vibices and petechiæ, and sometimes ulcers. As the column of blood pressing on the of origins of the veins of the lower extremities, when the body is erect, opposes the ascent of the blood in them, they are more frequently liable to become enlarged, and to produce varixes, or vibices, or, lastly, ulcers about the legs, than on the upper parts of the body. The exposure to cold is believed to be another cause of ulcers on the extremities; as happens to many of the poor in winter at Lisbon, who sleep in the open air, without stockings, on the steps of their churches or palaces. See Class I. 2. 1. 15. M. M. A bandage spread with plaster to cover the whole limb tight. Rags dipped in a solution of sugar of lead. A warm flannel stocking or roller. White lead and oak bark, both in fine powder. Horizontal rest. 15. _Scirrhus suppurans._ When a scirrhus affects any gland of no great extent or sensibility, it is, after a long period of time, liable to suppurate without inducing fever, like the indolent tumors of the conglobate or lymphatic glands above mentioned; whence collections of matter are often found after death both in men and other animals; as in the liver of swine, which have been fed with the grounds of fermented mixtures in the distilleries. Another termination of scirrhus is in cancer, as described below. See Class I. 2. 3. 22. 16. _Carcinoma._ Cancer. When a schirrous tumor regains its sensibility by nature, or by any accidental hurt, new vessels shoot amongst the yet insensible parts of it, and a new secretion takes place of a very injurious material. This cancerous matter is absorbed, and induces swelling of the neighbouring lymphatic glands; which also become schirrous, and afterwards cancerous. This cancerous matter does not seem to acquire its malignant or contagious quality, till the cancer becomes an open ulcer; and the matter secreted in it is thus exposed to the air. Then it evidently becomes contagious, because it not only produces hectic fever, like common matter in ulcers open to the air; but it also, as it becomes absorbed, swells the lymphatic glands in its vicinity; as those of the axilla, when the open cancer is on the breast. See Class II. 1. 3. Hence exsection before the cancer is open is generally a cure; but after the matter has been exposed to the air, it is seldom of service; as the neighbouring lymphatic glands are already infected. I have observed some of these patients after the operation to have had diseased livers, which might either have previously existed, or have been produced by the fear or anxiety attending the operation. Erosion with arsenic, after the cancer is become an open ulcer, has generally no better effect than exsection, but has been successful before ulceration. The best manner of using arsenic, is by mixing one grain with a dram of lapis calaminaris, and strewing on the cancer some of the powder every day, till the whole is destroyed. Cancers on the face are said to arise from the periosteum, and that unless this be destroyed by the knife, or by caustics, the cancer certainly recurs. After the cancer becomes an open ulcer of some extent, a purulent fever supervenes, as from other open ulcers, and gradually destroys the patient. See Class II. 1. 6. 13. Two very interesting cases have been lately published by Dr. Ewart, of Bath, in which carbonic acid gas, or fixed air, was kept constantly in contact with the open cancerous ulcers of the breast; which then healed like other common ulcers. This is rather to be ascribed to the exclusion of oxygen, than to any specific virtue in the carbonic acid. As in common ulcers the matter does not induce hectic fever, till it has been exposed to the air, and then probably united with oxygen. The manner of applying the fixed air, is by including the cancer in one half or hemisphere of a large bladder; the edges are made to adhere to the skin by adhesive plaster, or perhaps a mixture of one part of honey with about twenty parts of carpenter's glue might better suit some tender skins. The bladder is then kept constantly filled with carbonic acid gas, by means of a pipe in the neck of it; and the matter let out at a small aperture beneath. 17. _Arthrocele._ Swelling of the joints seems to have its remote cause in the softness of the bones, for they could not swell unless they were previously softened, see Class I. 2. 2. 14. The epiphyses, or ends of the bones, being naturally of a looser texture, are most liable to this disease, and perhaps the cartilages and capsular ligaments may also become inflamed and swelled along with the heads of the bones. This malady is liable to distort the fingers and knees, and is usually called gout or rheumatism; the former of which is liable to disable the fingers by chalk-stones, and thence to have somewhat a similar appearance. But the arthrocele, or swelling of the joints, affects people who have not been intemperate in the use of fermented or spirituous liquors; or who have not previously had a regular gout in their feet; and in both these circumstances differs from the gout. Nor does it accord with the inflammatory rheumatism, as it is not attended with fever, and because the tumors of the joints never entirely subside. The pain or sensibility, which the bones acquire, when they are inflamed, may be owing to the new vessels, which shoot in them in their soft state, as well as to the distention of the old ones. M. M. Half a grain of opium twice a day, gradually increased to a grain, but not further, for many months. Thirty grains of powder of bark twice a day for many months. Ten grains of bone-ashes, or calcined hartshorn, twice a day, with decoction of madder? Soda phosphorata? 18. _Arthropuosis._ Joint-evil. This differs from the former, as that never suppurates; these ulcers of the joints are generally esteemed to arise from scrophula; but as scrophula is a disease of the lymphatic or absorbent system, and this consists in the suppuration of the membranes, or glands, or cartilages about the joints, there does not seem a sufficient analogy to authorize their arrangement under the same name. The white swelling of the knee, when it suppurates, comes under this species, with variety of other ulcers attended with carious bones. 19. _Caries ossium._ A caries of the bones may be termed a suppuration of them; it differs from the above, as it generally is occasioned by some external injury, as in decaying teeth; or by venereal virus, as in nodes on the tibia; or by other matter derived to the bone in malignant fevers; and is not confined to the ends of them. The separation of the dead bone from the living is a work of some time. See Sect. XXXIII. 3. 1. * * * * * ORDO I. _Increased Sensation._ GENUS V. _With the Production of new Vessels by external Membranes or Glands, without Fever._ The ulcers, or eruptions, which are formed on the external skin, or on the mouth or throat, or on the air-cells of the lungs, or on the intestines, all of which are more or less exposed to the contact of the atmospheric air, which we breathe, and which in some proportion we swallow with our food and saliva; or to the contact of the inflammable air, or hydrogen, which is set at liberty by the putrefying aliment in the intestines, or by putrefying matter in large abscesses; all of them produce contagious matter; which, on being inoculated into the skin of another person, will produce fever, or a similar disease. In some cases even the matter formed beneath the skin becomes in some degree contagious, at least so much so as to produce fever of the hectic or malignant kind, as soon as it has pierced through the skin, and has thus gained access to some kind of air; as the fresh puss of a common abscess; or the putrid pus of an abscess, which has been long confined; or of cancerous ulcers. From this analogy there is reason to suspect, that the matter of all contagious diseases, whether with or without fever, is not infectious till it has acquired something from the air; which, by oxygenating the secreted matter, may probably produce a new acid. And secondly, that in hectic fever a part of the purulent matter is absorbed; or acts on the surface of the ulcer; as variolous matter affects the inoculated part of the arm. And that hectic fever is therefore caused by the matter of an open ulcer; and not by the sensation in the ulcer independent of the aerated pus, which lies on it. Which may account for the venereal matter from buboes not giving the infection, according to the experiments of the late Mr. Hunter, and for some other phenomena of contagion. See Variola discreta, Class II. 1. 3. 9. SPECIES. 1. _Gonorrhoea venerea._ A pus-like contagious material discharged from the urethra after impure cohabitation, with smarting or heat on making water; which begins at the external extremity of the urethra, to which the contagious matter is applied, and where it has access to the air. M. M. In this state of the venereal disease once venesection, with mild cathartics of senna and manna, with mucilage, as almond emulsion, and gum arabic, taken for two or three weeks, absolve the cure. Is camphor of use to relieve the ardor urinæ? Do balsams increase or lessen the heat of urine? Neutral salts certainly increase the smarting in making water, by increasing the acrimony of the urine. Can the discharge from the urethra be soon stopped by saturnine injections, or mercurial ones, or with solution of blue vitriol, at first very dilute, and gradually made stronger? And at the same time lest the syphilis, or general disease, should supervene, the patient might take a quarter of a grain of corrosive sublimate of mercury twice a day, as directed below? 2. _Syphilis._ Venereal disease. The contagion shews itself in ulcers on the part first inoculated, as chancres; ulcers on the tonsils succeed, with eruption on the skin, especially about the roots of the hair; afterwards on other parts of the skin, terminating in dry scabs; and lastly, with pain and swelling of the bones. The corona veneris, or crown of Venus, consists of the eruptions at the roots of the hair appearing most round the forehead; which is occasioned by this part being more exposed to the air; which we observed, at the beginning of this genus, either produces or increases the virulence of contagious matter. But it is difficult to conceive from this history, why the throat should be first affected; as it cannot be supposed, that the disease is so often taken by the saliva, like the small-pox, though this may sometimes occur, perhaps very often. The connection between the genitals in men and the throat, is treated of in Class IV. 1. 2. 7. Hydrophobia. M. M. A quarter of a grain of corrosive sublimate of mercury, taken thrice a day for five or six weeks, made into a pill with breadcrumbs, or dissolved in a spoonful of brandy and water, is a very efficacious and almost certain cure. When it does not succeed, it is owing either to the drug being bad, or to its having precipitated from the brandy, or from its being spoiled in the pill by long keeping. Opium contributes much to expedite the cure both of the simple gonorrhoea, and of venereal ulcers, by increasing absorption both from the mucous membrane, and from the surface of ulcers. 3. _Lepra._ Leprosy. Leprosy of the Greeks. The skin is rough with white branny scales, which are full of chinks; often moist beneath, and itching. The scales on the head or arms of some drinking people are a disease of this kind. The perspirable matter designed for the purpose of lubricating the external skin is secreted in this disease in a too viscid state, owing to the inflammation of the subcutaneous vessels; and, as the absorbents act too strongly at the same time, a viscid mucus is left adhering to the surface of the skin. In the leprosy of the Jews, described in the thirteenth and fourteenth chapters of Leviticus, the depression of the sore beneath the surface of the skin, and the hairs in it becoming white, seem to have been the principal circumstances, which the priest was directed to attend to for the purpose of ascertaining the disease. M. M. Essence of antimony from 20 drops to 100 twice or thrice a day, with half a pint of decoction of elm-bark; or tincture of cantharides from 20 to 60 drops four times a day; or sublimate of mercury, with much diluting fluid. Acid of vitriol? Perhaps the cure chiefly depends on much dilution with water, from two to four pints a day, in which elm-bark, or pine-buds, or juniper-tops, may be boiled. Bath or Buxton water drank in large quantities. Warm bath. Oil-skin bound on the part to confine the perspirable matter. Ointment of tar and suet; or poultice for two or three days, and then cerate with lapis calaminaris. Diet of raisins and bread. Abstinence from wine, beer, and all spirits. 4. _Elephantiasis._ Leprosy of the Arabs. A contagious disease; the skin is thickened, wrinkled, rough, unctuous, destitute of hair, without any sensation of touch in the extremities of the limbs; the face deformed with tubercles; the voice hoarse, and with a nasal tone. Cullen. 5. _Framboesia._ Yaws is said to be contagious and hereditary. It principally affects the negroes in the West Indies. Edinb. Essays, Vol. VI. 6. _Psora._ Itch. A contagious prurient eruption. There are two kinds of itch, that which appears between the fingers, and under the joints of the knees and elbows; and that which seldom is seen in these places, but all over the other parts of the body. The latter is seldom thought to be the itch, as it does not easily infect even a bedfellow, and resists the usual means of cure by brimstone. If the itch be cured too hastily by rubbing mercurial or arsenical preparations over the whole body, or on too great a part of it, many bad symptoms are produced; as weakness of digestion, with pale bloated countenance, and tendency to dropsy. I have twice seen St. Vitus's dance occur from the use of a mercurial girdle; and once a swelled liver. I have also seen a swelled spleen and swelled legs from the external use of arsenic in the cure of the itch. And very numerous and large phlegmons commonly succeed the too hasty cure of it by other means. There does not appear a strict analogy between the hasty cure of the itch, and the retrocession of the pustles in the secondary fever of the small-pox; because in that the absorption of the matter is evinced by the swelling of the face and hands, as the pustles recede, as explained in Class II. 1. 3. 9. Variola discreta. And a fever is produced by this absorption; neither of which happen, when the pustles of the itch are destroyed by mercury or arsenic. Nor can these inconveniences, which occur on the too hasty cure of the itch, be explained by those which follow the cure of some kinds of gutta rosea, Class II. 1. 4. 6. as in those the eruptions on the face were an associated disease with inflammation of the liver or stomach, which they were accustomed to relieve; whereas the itch is not known to have had any previous catenation with other diseases. In the itch there exists not only great irritation in the production of the pustles, but great sensation is caused by their acrimony afterwards; insomuch that the pain of itching, without the interrupted smarting occasioned by scratching, would be intolerable. This great excitement of the two sensorial powers of irritation and sensation is so great, when the pustles are diffused over the whole surface of the body, that a torpor succeeds the sudden ceasing of it; which affects those parts of the system, which were most catenated with the new motions of the skin, as the stomach, whence indigestion and flatulency; or which are generally most liable to fall into torpor, as the numerous glands, which form the liver. Whence the diseases consequent to the hasty cure of the itch are diseases of debility, as tumid viscera, oedematous swellings, and St. Vitus's dance, which is a debility of association. In the same manner indigestion, with green evacuations, are said to follow an injudicious application of cerussa to stop too hastily the exsudation behind the ears of children, Class I. 1. 2. 9. And dropsies are liable to succeed the cure of old ulcers of the legs, which have long stimulated the system. M. M. The size of a large pea, of an ointment consisting of one part of white precipitate of mercury to six parts of hogs' lard well triturated together, to be rubbed on a part of the body every night, and washed off with soap and water next morning, till every part is cleared; with lac sulphuris twenty grains to be taken every morning inwardly. Warm saline bath, with white vitriol in it. Flowers of sulphur mixed with thick gruel, with hogs fat. With either of which the body may be smeared all over. 7. _Psora ebriorum._ Elderly people, who have been much addicted to spirituous drinks, as beer, wine, or alcohol, are liable to an eruption all over their bodies; which is attended with very afflicting itching, and which they probably propagate from one part of their bodies to another with their own nails by scratching themselves. I saw fatal effects in one such patient, by a too extensive use of a solution of lead; the eruption disappeared, he became dropsical, and died; I suppose from the too suddenly ceasing of the great stimulus caused by the eruptions over the whole skin, as in the preceding article. M. M. The patient should gradually accustom himself to half his usual quantity of vinous potation. The warm bath, with one pound of salt to every three gallons. Mercurial ointments on small parts of the skin at a time. A grain of opium at night instead of the usual potation of wine or beer. 8. _Herpes._ Herpes consists of gregarious spreading excoriations, which are succeeded by branny scales or scabs. In this disease there appears to be a deficient absorption of the subcutaneous mucus, as well as inflammation and increased secretion of it. For the fluid not only excoriates the parts in its vicinity by its acrimony, but is very saline to the taste, as some of these patients have assured me; I believe this kind of eruption, as well as the tinea, and perhaps all other cutaneous eruption, is liable to be inoculated in other parts of the body by the finger-nails of the patients in scratching themselves. It is liable to affect the hands, and to return at distant periods; and is probably a secondary disease, as well as the zona ignea, or shingles, described below. M. M. Poultice the eruption with bread and milk, or raw carrots grated, for two or three whole days, to dilute or receive the discharged fluid, and abate the inflammation; then cover the parts with fresh cerate mixed with lapis calaminaris. On the parts not excoriated mercurial ointment, made of one part of white calx of mercury and six of hogs' fat. Internally, after venesection, gentle repeated cathartics. Lastly, the bark. Acid of vitriol. Bolus Armeniæ, or testacia. Antimonials. Decoction of interior bark of elm. 9. _Zona ignea._ Shingles. This eruption has been thought a species of herpes by some writers, and by others a species of erysipelas. Yellow or livid vesicles appear, producing a corrosive ichor, which is sometimes attended with a degree of fever. It is said to infest sometimes the thorax and ribs, but its most general situation is on the small of the back, over one kidney, extending forward over the course of one of the ureters. There is reason to suspect, that this also is a secondary or sympathetic disease, as well as the preceding one; but future observations are required, before it can be removed to the fourth class, or diseases of association. In three patients I have been induced to believe, that the eruption on the loins was a translation of inflammation from the external membrane of the kidney to the skin. They had, for a day or two before the appearance of the eruption, complained of a dull pain on the region of one kidney, but without vomiting; by which it was distinguished from nephritis interna, or gravel; and without pain down the outside of the thigh, by which it was distinguished from sciatica. In other situations the shingles may sympathize with other internal membranes, as in a case published by Dr. Russel (De Tabe Glandulari), where the retrocession of the shingles was succeeded by a serious dyspnæa. M. M. Venesection, if the pulse is strong. Calomel three or four grains, very mild repeated cathartics. Poultice for a few days, then cerate of lapis calaminaris, as in herpes. A grain of emetic tartar dissolved in a pint of water, and taken so as to empty the stomach and intestines, is said much to hasten the cure; compresses soaked in a saturnine solution are recommended externally on the eruption; and cerate where there are ulcerations. Desanet's Surgical Journal, Vol. II. p. 378. If this be a vicarious disease, it should continue half a lunation; lest, on its ceasing, the bad habits of motion of the primary disease should not have been so perfectly dissevered, but that they may recur. 10. _Annulus repens._ Ring-worm. A prurient eruption formed in a circle, affecting children, and would seem to be the work of insects, according to the theory of Linnæus, who ascribes the itch and dysentery to microscopic animalcula. These animalcula are probably the effect, and not the cause, of these eruptions; as they are to be seen in all putrescent animal fluids. The annular propagation of the ring-worm, and its continuing to enlarge its periphery, is well accounted for by the acrimony of the ichor or saline fluid eroding the skin in its vicinity. M. M. Cover the eruption daily with ink. With white mercurial ointment, as described above in herpes. With solution of white vitriol ten grains to an ounce. These metallic calces stimulate the absorbents into stronger action, whence the fluid has its saline part reabsorbed, and that before it has access to the air, which probably adds to its acrimony by oxygenating it, and thus, producing a new acid. 11. _Tinea._ Scald head. This contagious eruption affects the roots of the hair, and is generally most virulent around the edges of the hair on the back part of the head; as the corona veneris appears most on the edges of the hair on the forepart of the head; for in these parts the eruption about the roots of the hair is most exposed to the external air, by which its acrimony or noxious quality is increased. The absorption of the matter thus oxygenated swells the lymphatics of the neck by its stimulus, occasioning many little hard lumps beneath the seat of the eruption; when this happens, the sooner it is cured the better, lest the larger lymphatics of the neck should become affected. M. M. The art of curing these eruptions consists, first, in abating the inflammation, and consequent secretion of a noxious material. Secondly, to prevent its access to the air, which so much increases its acrimony. And thirdly, to promote the absorption of it, before it has been exposed to the air; for these purposes venesection once, and gentle cathartics, which promote absorption by emptying the blood-vessels. Next poultices and fomentations, with warm water, abate inflammation by diluting the saline acrimony of the secreted fluid, and abating the painful sensation. Afterwards cerate joined with some metallic calx, as of zinc or lead, or solution of lead, mercury, or copper, or iron, which may stimulate the absorbent system into stronger action. Cover the shaved head with tar and suet, and a bladder; this, by keeping the air from the secreted fluid, much contributes to its mildness, and the stimulus of the tar increases its absorption. See the three preceding species of this genus. 12. _Crusta lactea._ Milk-crust is a milder disease than tinea, affecting the face as well as the hairy scalp of very young children. It is not infectious, nor liable to swell the lymphatics in its vicinity like the tinea. M. M. Cover the eruption with cerate made with lapis calaminaris, to be renewed every day. Mix one grain of emetic tartar with forty grains of chalk, and divide into eight papers, one to be taken twice a day, or with magnesia alba, if stools are wanted. The child should be kept cool and much in the air. 13. _Trichoma._ Plica polonica. A contagious disease, in which the hair is said to become alive and bleed, forming inextricable knots or plaits of great length, like the fabled head of Medusa, with intolerable pain, so as to confine the sufferer on his bed for years. * * * * * ORDO I. _Increased Sensation._ GENUS VI. _With Fever consequent to the Production of new Vessels or Fluids._ SPECIES. 1. _Febris sensitiva._ Sensitive fever, when unmixed with either irritative or inirritative fever, may be distinguished from either of them by the less comparative diminution of muscular strength; or in other words, from its being attended with less diminution of the sensorial power of irritation. An example of unmixed sensitive fever may generally be taken from the pulmonary consumption; in this disease patients are seen to walk about with ease, and to do all the common offices of life for weeks, and even months, with a pulse of 120 strokes in a minute; while in other fevers, whether irritated or inirritated, with a pulse of this frequency, the patient generally lies upon the bed, and exerts no muscular efforts without difficulty. The cause of this curious phenomenon is thus to be understood; in the sensitive fever a new sensorial power, viz. that of sensation, is superadded to that of irritation; which in other fevers alone carries on the increased circulation. Whence the power of irritation is not much more exhausted than in health; and those muscular motions, which are produced in consequence of it, as those which are exerted in keeping the body upright in walking, riding, and in the performance of many customary actions, are little impaired. For an account of the irritated sensitive fever, see Class II. 1. 2. 1.; for the inirritated sensitive fever, Class II. 1. 3. 1. IV. 2. 4. 11. 2. _Febris a pure clauso._ Fever from inclosed matter is generally of the irritated sensitive kind, and continues for many weeks, and even months, after the abscess is formed; but is distinguished from the fever from aerated matter in open ulcers, because there are seldom any night-sweats, or colliquative diarrhoea in this, as in the latter. The pulse is also harder, and requires occasional venesection, and cathartics, to abate the inflammatory fever; which is liable to increase again every three or four days, till at length, unless the matter has an exit, it destroys the patient. In this fever the matter, not having been exposed to the air, has not acquired oxygenation; in which a new acid, or some other noxious property, is produced; which acts like contagion on the constitution inducing fever-fits, called hectic fever, which terminate with sweats or diarrhoea; whereas the matter in the closed abscess is either not absorbed, or does not so affect the circulation as to produce diurnal or hectic fever-fits; but the stimulus of the abscess excites so much sensation as to induce perpetual pyrexia, or inflammatory fever, without such marked remissions. Nevertheless there sometimes is no fever produced, when the matter is lodged in a part of little sensibility, as in the liver; yet a white pus-like sediment in those cases exists I believe generally in the urine, with occasional wandering pains about the region of the liver or chest. 3. _Vomica._ An abscess in the lungs is sometimes produced after peripneumony, the cough and shortness of breath continue in less degree, with difficulty in lying on the well side, and with sensitive irritated fever, as explained in the preceding article. The occasional increase of fever, with hard pulse and sizy blood, in these patients, is probably owing to the inflammation of the walls of the vomica; as it is attended with difficulty of breathing, and requires venesection. Mr. B----, a child about seven years old, lived about five weeks in this situation, with a pulse from 150 to 170 in a minute, without sweats, or diarrhoea, or sediment in his water, except mucus occasionally; and took sufficient nourishment during the whole time. The blood taken was always covered with a strong cupped size, and on his death three or four pints of matter were found in one side of the chest; which had probably, but lately, been effused from a vomica. This child was frequently induced to swing, both in a reciprocating and in a rotatory swing, without any apparent absorption of matter; in both these swings he expressed pleasure, and did not appear to be vertiginous. M. M. Repeated emetics. Digitalis? Perseverance in rotatory swinging. See Class II. 1. 6. 7. Mr. I. had laboured some months under a vomica after a peripneumony, he was at length taken with a catarrh, which was in some degree endemic in March 1795, which occasioned him to sneeze much, during which a copious hæmorrhage from the lungs occurred, and he spit up at the same time half a pint of very fetid matter, and recovered. Hence errhines may be occasionally used with advantage. 4. _Empyema._ When the matter from an abscess in the lungs finds its way into the cavity of the chest, it is called an empyema. A servant man, after a violent peripneumony, was seized with symptoms of empyema, and it was determined, after some time, to perform the operation; this was explained to him, and the usual means were employed by his friends to encourage him, "by advising him not to be afraid." By which good advice he conceived so much fear, that he ran away early next morning, and returned in about a week quite well. Did the great fear promote the absorption of the matter, like the sickness occasioned by digitalis? Fear renders the external skin pale; by this continued decrease of the action of the absorbents of the skin might not those of the lungs be excited into greater activity? and thus produce increased pulmonary absorption by reverse sympathy, as it produces pale urine, and even stools, by direct sympathy? M.M. Digitalis? 5. _Febris Mesenterica._ Fever from matter formed in the mesentery is probably more frequent than is suspected. It commences with pain in the bowels, with irritated sensitive fever; and continues many weeks, and even months, requiring occasional venesection, and mild cathartics; till at length the continuance of the pyrexia, or inflammatory fever, destroys the patient. This is an affection of the lymphatic glands, and properly belongs to scrophula; but as the matter is not exposed to the air, no hectic fever, properly so called, is induced. 6. _Febris a pure aerato._ Fever from aerated matter. A great collection of matter often continues a long time, and is sometimes totally absorbed, even from venereal buboes, without producing any disorder in the arterial system. At length, if it becomes putrid by its delay, and one part of the matter thus becomes aerated by the air given out by the other part; or if the ulcer has been opened, so that any part of it has been exposed to the air for but one day, a hectic fever is produced. Whence the utility arises of opening large abscesses by setons, as in that case little or no hectic fever is induced; because the matter is squeezed out by the side of the spongy threads of cotton, and little or no air is admitted; or by tapping the abscess with a trocar, as mentioned in ischias, Class II. 1. 2. 18. In this fever the pulse is about 120 in a minute, and its access is generally in an evening, and sometimes about noon also, with sweats or purging towards morning, or urine with pus-like sediment; and the patients bear this fever better than any other with so quick a pulse; and lastly, when all the matter from a concealed ulcer is absorbed, or when an open ulcer is healed, the hectic fever ceases. Here the absorbed matter is supposed to produce the fever, and the diarrhoea, sweats, or copious muddy urine, to be simply the consequence of increased secretion, and not to consist of the purulent matter, which was supposed to be absorbed from the ulcer. See Sudor calidus, Class I. 1. 2. 3. The action of the air on ulcers, as we have already shewn, increases the acrimony of the purulent matter, and even converts it into a weaker kind of contagious matter; that is, to a material inducing fever. This was ascribed to the union of the azotic part of the atmosphere with the effused pus in Sect. XXVIII. 2. but by contemplating more numerous facts and analogies, I am now induced to believe, that it is by the union of oxygen with it; first, because oxygen so greedily unites with other animal substances, as the blood, that it will pass through a moist bladder to combine with it, according to the experiment of Dr. Priestley. Secondly, because the poisons of venomous creatures are supposed to be acids of different kinds, and are probably formed by the contact of air after their secretion. And lastly, because the contagious matter from other ulcers, as in itch, or small-pox, are formed on external membranes, and are probably combinations of animal matter and oxygen, producing other new acids; but further experiments must determine this question. It was thought a subject of consequence by the Æsculapian Society at Edinburgh, to find a criterion which should distinguish pus from mucus, for the purpose of more certainly discovering the presence of ulcers in pulmonary diseases, or in the urinary passages. For this purpose that society offered their first gold medal, which was conferred on the late Mr. Charles Darwin, in the year 1778, for his experiments on this subject. From which he deduces the following conclusions: "1. Pus and mucus are both soluble in the vitriolic acid, though in very different proportions, pus being much the less soluble. 2. The addition of water to either of these compounds decomposes it; the mucus thus separated, either swims on the mixture, or forms large flocci in it; whereas the pus falls to the bottom, and forms on agitation a uniform turbid mixture. 3. Pus is diffusible through a diluted vitriolic acid, though mucus is not; the same occurs with water, or a solution of sea salt. 4. Nitrous acid dissolves both pus and mucus; water added to the solution of pus produces a precipitate; and the fluid above becomes clear and green; while water and the solution of mucus form a dirty coloured fluid. 5. Alkaline lixivium dissolves (though sometimes with difficulty) mucus, and generally pus. 6. Water precipitates pus from such a solution, but does not mucus. 7. Where alkaline lixivium does not dissolve pus, it still distinguishes it from mucus; as it then prevents its diffusion through water. 8. Coagulable lymph is neither soluble in diluted nor concentrated vitriolic acid. 9. Water produces no change on a solution of serum in alkaline lixivium, until after long standing, and then only a very slight sediment appears. 10. Corrosive sublimate coagulates mucus, but does not pus. From the above experiments it appears, that strong vitriolic acid and water, diluted vitriolic acid, and caustic alkaline lixivium and water will serve to distinguish pus from mucus; that the vitriolic acid can separate it from coagulable lymph, and alkaline lixivium from serum. And hence, when a person has any expectorated material, the composition of which he wishes to ascertain, let him dissolve it in vitriolic acid, and in caustic alkaline lixivium; and then add pure water to both solutions: and if there is a fair precipitation in each, he may be assured that some pus is present. If in neither a precipitation occurs, it is a certain test, that the material is entirely mucus. If the material cannot be made to dissolve in alkaline lixivium by time and trituration, we have also reason to believe that it is pus." Experiments on Pus and Mucus. Cadell. London. 7. _Phthisis pulmonalis._ In pulmonary consumption the fever is generally supposed to be the consequence of the stimulus of absorbed matter circulating in the blood-vessels, and not simply of its stimulus on their extremities in the surface of the ulcers; as mentioned in Class II. 1. 5. and Class II. 1. 3. 9. The ulcers are probably sometimes occasioned by the putrid acrimony of effused blood remaining in the air-cells of the lungs after an hæmoptoe. See Class I. 2. 1. 9. The remote cause of consumption is ingeniously ascribed by Dr. Beddoes to the hyper-oxygenation of the blood, as mentioned Section XXVIII. 2. As the patients liable to consumption are of the inirritable temperament, as appears by the large pupils of their eyes; there is reason to believe, that the hæmoptoe is immediately occasioned by the deficient absorption of the blood at the extremities of the bronchial vein; and that one difficulty of healing the ulcers is occasioned by the deficient absorption of the fluids effused into them. See Sect. XXX. 1. and 2. The difficulty of healing pulmonary ulcers may be owing, as its remote cause, to the incessant motion of all the parts of the lungs; whence no scab, or indurated mucus, can be formed so as to adhere on them. Whence these naked ulcers are perpetually exposed to the action of the air on their surfaces, converting their mild purulent matter into a contagious ichor; which not only prevents them from healing, but by its action on their circumferences, like the matter of itch or tinea, contributes to spread them wider. See the preceding article, and Sect. XXXIII. 2. 7. where the pulmonary phthisis is supposed to be infectious. This acidifying principle is found in all the metallic calces, as in lapis calaminaris, which is a calciform ore of zinc; and in cerussa, which is a calx of lead; two materials which are powerful in healing excoriations, and ulcers, in a short time by their external application. How then does it happen, that the oxygen in the atmosphere should prevent pulmonary ulcers from healing, and even induce them to spread wider; and yet in its combination with metals, it should facilitate their healing? The healing of ulcers consists in promoting the absorption of the fluids effused into them, as treated of in Section XXXIII. 3. 2. Oxygen in combination with metals, when applied in certain quantity, produces this effect by its stimulus; and the metallic oxydes not being decomposed by their contact with animal matter, no new acid, or contagious material, is produced. So that the combined oxygen, when applied to an ulcer, simply I suppose promotes absorption in it, like the application of other materials of the articles sorbentia or incitantia, if applied externally; as opium, bark, alum. But in the pulmonary ulcers, which cannot protect themselves from the air by forming a scab, the uncombined oxygen of the atmosphere unites with the purulent matter, converting it into a contagious ichor; which by infection, not by erosion, enlarges the ulcers, as in the itch or tinea; which might hence, according to Dr. Beddoes's ingenious theory of consumption, be induced to heal, if exposed to an atmosphere deprived of a part of its oxygen. This I hope future experiments will confirm, and that the pneumatic medicine will alleviate the evils of mankind in many other, as well as in this most fatal malady. M. M. First, the respiration of air lowered by an additional quantity of azote, or mixed with some proportion of hydrogen, or of carbonic acid air, may be tried; as described in a late publication of Dr. Beddoes on the medicinal use of factitious airs. Johnson, London. Or lastly, by breathing a mixture of one tenth part of hydro-carbonate mixed with common air, according to the discovery of Mr. Watt, which has a double advantage in these cases, of diluting the oxygen of the atmospheric air, and inducing sickness, which increases pulmonary absorption, as mentioned below. An atmosphere diluted with fixed air (carbonic acid) might be readily procured by setting tubs of new wort, or fermenting beer, in the parlour and lodging-room of the patient. For it is not acids floating in the air, but the oxygen or acidifying principle, which injures or enlarges pulmonary ulcers by combining with the purulent matter. Another easy method of adding carbonic acid gas to the air of a room, would be by means of an apparatus invented by Mr. Watt, and sold by Bolton and Watt at Birmingham, as described in Dr. Beddoes' Treatise on Pneumatic Medicine. Johnson, London. It consists of an iron pot, with an arm projecting, and a method of letting water drop by slow degrees on chalk, which is to be put into the iron pot, and exposed to a moderate degree of heat over a common fire. By occasionally adding more and more chalk, carbonic acid gas might be carried through a tin pipe from the arm of the iron pot to any part of the room near the patient, or from an adjoining room. In the same manner a diffusion of solution of flowers of zinc might be produced and breathed by the patient, and would be likely much to contribute to the healing of pulmonary ulcers; as observed by Mr. Watt. See the treatise above mentioned. Breathing over the vapour of caustic volatile alkali might easily be managed for many hours in a day; which might neutralize the acid poison formed on pulmonary ulcers by the contact of oxygen, and thus prevent its deleterious quality, as other acids become less caustic, when they are formed into neutral salts with alkalis. The volatile salt should be put into a tin canister, with two pipes like horns from the top of it, one to suck the air from, and the other to admit it. [Illustration] Secondly, the external ulcers in scrophulous habits are pale and flabby, and naturally disinclined to heal, the deposition of fluids in them being greater than the absorption; these ulcers have their appearance immediately changed by the external application of metallic calxes, and the medicines of the article Sorbentia, such as cerussa and the bark in fine powder, see Class I. 2. 3. 21. and are generally healed in a short time by these means. Induced by these observations, I wished to try the external application of such powders to ulcers in the lungs, and constructed a box with a circulating brush in it, as described in the annexed plate; into this box two ounces of fine powder of Peruvian bark were put, and two drams of cerussa in fine powder; on whirling the central brush, part of this was raised into a cloud of powder, and the patient, applying his mouth to one of the tin pipes rising out of the box, inhaled this powder twice a day into his lungs. I observed it did not produce any cough or uneasiness. This patient was in the last stage of consumption, and was soon tired of the experiment, nor have I had such patients as I wished for the repetition of it. Perhaps a fine powder of manganese, or of the flowers of zinc, or of lapis calaminaris, might be thus applied to ulcers of the lungs with greater advantage? Perhaps air impregnated with flowers of zinc in their most comminuted state, might be a better way of applying this powder to the lungs, as discovered by Mr. Watt. See Dr. Beddoes on Pneumatic Medicine. Johnson. Thirdly, as the healing of an ulcer consists in producing a tendency to absorption on its surface greater than the deposition on it; see Sect. XXXIII. 3. 2. other modes of increasing pulmonary absorption, which are perhaps more manageable than the preceding ones, may be had recourse to; such as by producing frequent nausea or sickness. See Sect. XXIX. 5. 1. and Art. IV. 2. The great and sudden absorption of fluid from the lungs in the anasarca pulmonum by the sickness induced by the exhibition of digitalis, astonishes those who have not before attended to it, by emptying the swelled limbs, and removing the difficulty of breathing in a few hours. The most manageable method of using digitalis is by making a saturated tincture of it, by infusing two ounces of the powder of the leaves in a mixture of four ounces of rectified spirit of wine, and four ounces of water. Of this from 30 to 60 drops, or upwards, from a two-ounce phial, are to be taken twice in the morning part of the day, and to be so managed as not to induce violent sickness. If sickness nevertheless comes on, the patient must for a day or two omit the medicine; and then begin it again in reduced doses. Mr. ----, a young man about twenty, with dark eyes, and large pupils, who had every symptom of pulmonary ulcers, I believed to have been cured by digitalis, and published the case in the Transactions of the College, Vol. III. But about two years afterwards I heard that he relapsed and died. Mr. L----, a corpulent man, who had for some weeks laboured under a cough with great expectoration, with quick pulse, and difficulty of breathing, soon recovered by the use of digitalis taken twice a day; and though this case might probably be a peripneumonia notha, or catarrh, it is here related as shewing the power of pulmonary absorption excited by the use of this drug. Another method of inducing sickness, and pulmonary absorption in consequence, is by sailing on the sea; by which many consumptive patients have been said to have received their cure; which has been erroneously ascribed to sea-air, instead of sea-sickness; whence many have been sent to breathe the sea-air on the coasts, who might have done better in higher situations, where the air probably contains less oxygen gas, which is the heaviest part of it. See a Letter from Dr. T. C. below. A third method of inducing sickness, and consequent pulmonary absorption, is by the vertigo occasioned by swinging; which has lately been introduced into practice by Dr. Smith, (Essay on Pulmonary Consumption), who observed that by swinging the hectic pulse became slower, which is explained in Class IV. 2. 1. 10. The usual way of reciprocating swinging, like the oscillations of a pendulum, produces a degree of vertigo in those, who are unused to it; but to give it greater effect, the patient should be placed in a chair suspended from the ceiling by two parallel cords in contact with each other, the chair should then be forcibly revolved 20 or 40 times one way, and suffered to return spontaneously; which induces a degree of sickness in most adult people, and is well worthy an exact and pertinacious trial, for an hour or two, three or four times a day for a month. The common means of promoting absorption in ulcers, and of thickening the matter in consequence, by taking the bark and opium internally, or by metallic salts, as of mercury, steel, zinc, and copper, in small quantities, have been repeatedly used in pulmonary consumption; and may have relieved some of the symptoms. As mercury cures venereal ulcers, and as pulmonary ulcers resemble them in their not having a disposition to heal, and in their tendency to enlarge themselves, there were hopes, from analogy, that it might have succeeded. Would a solution of gold in aqua regia be worth trying? When vinegar is applied to the lips, it renders them instantly pale, by promoting the venous absorption; if the whole skin was moistened with warmish vinegar, would this promote venous absorption in the lungs by their sympathy with the skin? The very abstemious diet on milk and vegetables alone is frequently injurious. Flesh-meat once a day, with small wine and water, or small beer, is preferable. Half a grain of opium twice a day, or a grain, I believe to be of great use at the commencement of the disease, as appears from the subsequent case. Miss ----, a delicate young lady, of a consumptive family, when she was about eighteen, had frequent cough, with quick pulse, a pain of her side, and the general appearances of a beginning consumption. She took about five drops of laudanum twice a day in a saline draught, which was increased gradually to ten. In a few weeks she recovered, was afterwards married, bore three or four children, and then became consumptive and died. The following case of hereditary consumption is related by a physician of great ability and very extensive practice; and, as it is his own case, abounds with much nice observation and useful knowledge; and, as it has been attended with a favourable event, may give consolation to many, who are in a similar situation; and shews that Sydenham's recommendation of riding as a cure for consumption is not so totally ineffectual, as is now commonly believed. "J. C. aged 27, with black hair, and a ruddy complexion, was subject to cough from the age of puberty, and occasionally to spitting of blood. His maternal grandfather died of consumption under thirty years of age, and his mother fell a victim to this disease, with which she had long been threatened, in her 43d year, and immediately after she ceased to have children. In the severe winter of 1783-4, he was much afflicted with cough; and being exposed to intense cold, in the month of February he was seized with peripneumony. The disease was violent and dangerous, and after repeated bleedings as well as blisterings, which he supported with difficulty, in about six weeks he was able to leave his bed. At this time the cough was severe, and the expectoration difficult. A fixed pain remained on the left side, where an issue was inserted; regular hectic came on every day about an hour after noon, and every night heat and restlessness took place, succeeded towards morning by general perspiration. The patient, having formerly been subject to ague, was struck with the resemblance of the febrile paroxysm, with what he had experienced under that disease, and was willing to flatter himself it might be of the same nature. He therefore took bark in the interval of fever, but with an increase of his cough, and this requiring venesection, the blood was found highly inflammatory. The vast quantity of blood which he had lost from time to time, produced a disposition to fainting, when he resumed the upright posture, and he was therefore obliged to remain almost constantly in a recumbent position. Attempting to ride out in a carriage, he was surprised to find that he could sit upright for a considerable time, while in motion, without inconvenience, though, on stopping the carriage, the disposition to fainting returned. At this time, having prolonged his ride beyond the usual length, he one day got into an uneven road at the usual period of the recurrence of the hectic paroxysms, and that day he missed it altogether. This circumstance led him to ride out daily in a carriage at the time the febrile accession might be expected, and sometimes by this means it was prevented, sometimes deferred, and almost always mitigated. This experience determined him to undertake a journey of some length, and Bristol being, as is usual in such cases, recommended, he set out on the 19th of April, and arrived there on the 2d of May. During the greater part of this journey (of 175 miles) his cough was severe, and being obliged to be bled three different times on the road, he was no longer able to sit upright, but at very short intervals, and was obliged to lie at length in the diagonal of a coach. The hectic paroxysms were not interrupted during the journey, but they were irregular and indistinct, and the salutary effects of exercise, or rather of gestation, were impressed on the patient's mind. At Bristol he stayed a month, but reaped no benefit. The weather was dry and the roads dusty; the water insipid and inert. He attempted to ride on horseback on the downs, but was not able to bear the fatigue for a distance of more than a hundred yards. The necessity of frequent bleedings kept down his strength, and his hectic paroxysms continued, though less severe. At this time, suspecting that his cough was irritated by the west-winds bearing the vapour from the sea, he resolved to try the effects of an inland situation, and set off for Matlock in Derbyshire. During the journey he did not find the improvement he expected, but the nightly perspirations began to diminish; and the extraordinary fatigue he experienced proceeded evidently from his travelling in a post-chaise, where he could not indulge in a recumbent position. The weather at Bristol had been hot, and the earth arid and dusty. At Matlock, during the month of June 1784, there was almost a perpetual drizzle, the soil was wet, and the air moist and cold. Here, however, the patient's cough began to abate, and at intervals he found an opportunity of riding more or less on horseback. From two or three hundred yards at a time, he got to ride a mile without stopping; and at length he was able to sit on horseback during a ride from Mason's Bath to the village of Matlock along the Derwent, and round on the opposite banks, by the works of Mr. Arkwright, back to the house whence he started, a distance of five miles. On dismounting, however, he was seized with diliquium, and soon after the strength he had recovered was lost by an attack of the hæmorrhoids of the most painful kind, and requiring much loss of blood from the parts affected. On reflection, it appeared that the only benefit received by the patient was during motion, and continued motion could better be obtained in the course of a journey than during his residence at any particular place. This, and other circumstances of a private but painful nature, determined him to set out from Matlock on a journey to Scotland. The weather was now much improved, and during the journey he recruited his strength. Though as yet he could not sit upright at rest for half an hour together without a disposition to giddiness, dimness of sight, and deliquium, he was able to sit upright under the motion of a post-chaise during a journey of from 40 to 70 miles daily, and his appetite began to improve. Still his cough continued, and his hectic flushings, though the chills were much abated and very irregular. The salutary effects of motion being now more striking than ever, he purchased a horse admirably adapted to a valetudinarian in Dumfriesshire, and being now able to sit on horseback for an hour together, he rode out several times a day. He fixed his residence for a few weeks at Moffat, a village at the foot of the mountains whence the Tweed, the Clyde, and the Annan, descend in different directions; a situation inland, dry, and healthy, and elevated about three hundred feet above the surface of the sea. Here his strength recovered daily, and he began to eat animal food, which for several months before he had not tasted. Persevering in exercise on horseback, he gradually increased the length of his rides, according to his strength, from four to twenty miles a day; and returning on horseback to Lancashire by the lakes of Cumberland, he arrived at Liverpool on the first of September, having rode the last day of his journey forty miles. The two inferences of most importance to be drawn from this narrative, are, first, the extraordinary benefit derived from gestation in a carriage, and still more the mixture of gestation and exercise on horseback, in arresting or mitigating the hectic paroxysm; and secondly, that in the florid consumption, as Dr. Beddoes terms it, an elevated and inland air is in certain circumstances peculiarly salutary; while an atmosphere loaded with the spray of the sea is irritating and noxious. The benefit derived in this case from exercise on horseback, may lead us to doubt whether Sydenham's praise of this remedy be as much exaggerated as it has of late been supposed. Since the publication of Dr. C. Smyth on the effects of swinging in lowering the pulse in the hectic paroxysm, the subject of this narrative has repeated his experiments in a great variety of cases, and has confirmed them. He has also repeatedly seen the hectic paroxysm prevented, or cut short, by external ablution of the naked body with tepid water. So much was his power of digestion impaired or vitiated by the immense evacuations, and the long continued debility he underwent, that after the cough was removed, and indeed for several years after the period mentioned, he never could eat animal food without heat and flushing, with frequent pulse and extreme drowsiness. If this drowsiness was encouraged, the fever ran high, and he awoke from disturbed sleep, wearied and depressed. If it was resolutely resisted by gentle exercise, it went off in about an hour, as well as the increased frequency of the pulse. This agitation was however such as to incapacitate him during the afternoon for study of any kind. The same effects did not follow a meal of milk and vegetables, but under this diet his strength did not recruit; whereas after the use of animal food it recovered rapidly, notwithstanding the inconvenience already mentioned. For this inconvenience he at last found a remedy in the use of coffee immediately after dinner, recommended to him by his friend Dr. Percival. At first this remedy operated like a charm, but by frequent use, and indeed by abuse, it no longer possesses its original efficacy. Dr. Falconer, in his Dissertation on the Influence of the Passions and Affections of the Mind on Health and Disease, supposes that the cheerfulness which attends hectic fever, the ever-springing hope, which brightens the gloom of the consumptive patient, increases the diseased actions, and hastens his doom. And hence he is led to enquire, whether the influence of fear might not be substituted in such cases to that of hope with advantage to the patient? This question I shall not presume to answer, but it leads me to say something of the state of the mind in the case just related. The patient, being a physician, was not ignorant of his danger, which, some melancholy circumstances served to impress on his mind. It has already been mentioned, that his mother and grandfather died of this disease. It may be added, that in the year preceding that on which he himself was attacked, a sister of his was carried off by consumption in her 17th year; that in the same winter in which he fell ill, two other sisters were seized with the same fatal disorder, to which one of them fell a victim during his residence at Bristol, and that the hope of bidding a last adieu to the other was the immediate cause of his journey to Scotland, a hope which, alas! was indulged in vain. The day on which he reached the end of his journey, her remains were committed to the dust! It may be conjectured from these circumstances, that whatever benefit may be derived from the apprehension of death, must in this case have been obtained. The expectation of this issue was indeed for some time so fixed that it ceased to produce much agitation; in conformity to that general law of our nature, by which almost all men submit with composure to a fate that is foreseen, and that appears inevitable. As however the progress of disease and debility seemed to be arrested, the hope and the love of life revived, and produced, from time to time, the observations and the exertions already mentioned. Wine and beer were rigorously abstained from during six months of the above history; and all the blood which was taken was even to the last buffy." Feb. 3, 1795. 8. _Febris scrophulosa._ The hectic fever occasioned by ulcers of the lymphatic glands, when exposed to the air, does not differ from that attending pulmonary consumption, being accompanied with night-sweats and occasional diarrhoea. M. M. The bark. Opium internally. Externally cerussa and bark in fine powder. Bandage. Sea-bathing. See Class I. 2. 3. 21. and II. 1. 4. 13. 9. _Febris ischiadica._ A hectic fever from an open ulcer between the muscles of the pelvis, which differs not from the preceding. If the matter in this situation lodges till part of it, I suppose, becomes putrid, and aerates the other part; or till it becomes absorbed from some other circumstance; a similar hectic fever is produced, with night-sweats, or diarrhoea. Mrs. ----, after a lying in, had pain on one side of her loins, which extended to the internal part of the thigh on the same side. No fluctuation of matter could be felt; she became hectic with copious night-sweats, and occasional diarrhoea, for four or five weeks; and recovered by, I suppose, the total absorption of the matter, and the reunion of the walls of the abscess. See Class II. 1. 2. 18. 10. _Febris Arthropuodica._ Fever from the matter of diseased joints. Does the matter from suppurating bones, which generally has a very putrid smell, produce hectic fever, or typhus? See Class II. 1. 4. 16. 11. _Febris a pure contagioso._ Fever from contagious pus. When the contagious matters have been produced on the external habit, and in process of time become absorbed, a fever is produced in consequence of this reabsorption; which differs with the previous irritability or inirritability, as well as with the sensibility of the patient. 12. _Febris variolosa secundaria._ Secondary fever of small-pox. In the distinct small-pox the fever is of the sensitive irritated or inflammatory kind; in the confluent small-pox it is of the sensitive inirritated kind, or typhus gravior. In both of them the swelling of the face, when the matter there begins to be absorbed, and of the hands, when the matter there begins to be absorbed, shew, that it stimulates the capillary vessels or glands, occasioning an increased secretion greater than the absorbents can take up, like the action of the cantharides in a blister; now as the application of a blister on the skin frequently occasions the strangury, which shews, that some part of the cantharides is absorbed; there is reason to conclude, that a part of the matter of small-pox is absorbed, and thus produces the secondary fever. See Class II. 1. 3. 9. And not simply by its stimulus on the surface of the ulcers beneath the scabs. The exsudation of a yellow fluid from beneath the confluent eruptions on the face before the height is spoken of in Class II. 1. 3. 2. The material thus absorbed in the secondary fever of small-pox differs from that of open ulcers, as it is only aerated through the elevated cuticle; and secondly, because there is not a constant supply of fresh matter, when that already in the pustules is exhausted, either by absorption, or by evaporation, or by its induration into a scab. Might not the covering the face assiduously and exactly with plasters, as with cerate of calamy, or with minium plaster, by precluding the air from the pustules, prevent their contracting a contagious, or acescent, or fever-producing power? and the secondary fever be thus prevented entirely. If the matter in those pustules on the face in the confluent small-pox were thus prevented from oxygenation, it is highly probable, both from this theory, and from the facts before mentioned, that the matter would not erode the skin beneath them, and by these means no marks or scars would succeed. 13. _Febris carcinomatosa._ Fever from the matter of cancer. In a late publication the pain is said to be relieved, and the fever cured, and the cancer eradicated, by the application of carbonic acid gas, or fixed air. See Class II. 1. 4. 16. 14. _Febris venerea._ From the absorption of the matter from venereal ulcers and suppurating bones. See Syphilis, II. 1. 5. 2. M. M. Any mercurial calx. Sarsaparilla? Mezereon? 15. _Febris a sanie putrida._ Fever from putrid sanies. When parts of the body are destroyed by external violence, as a bruise, or by mortification, a putrefaction soon succeeds; as they are kept in that degree of warmth and moisture by their adhesion to the living parts of the body, which most forwards that process. Thus the sloughs of mortified parts of the tonsils give fetor to the breath in some fevers; the matter from putrefying teeth, or other suppurating bones, is particularly offensive; and even the scurf, which adheres to the tongue, frequently acquires a bitter taste from its incipient putridity. This material differs from those before mentioned, as its deleterious property depends on a chemical rather than an animal process. 16. _Febris puerpera._ Puerperal fever. It appears from some late dissections, which have been published, of those women who have died of the puerperal fever, that matter has been formed in the omentum, and found in the cavity of the abdomen, with some blood or sanies. These parts are supposed to have been injured by the exertions accompanying labour; and as matter in this viscus may have been produced without much pain, this disease is not attended with arterial strength and hard full pulse like the inflammation of the uterus; and as the fever is of the inirritative or typhus kind, there is reason to believe, that the previous exhaustion of the patient during labour may contribute to its production; as well as the absorption of a material not purulent but putrid; which is formed by the delay of extravasated or dead matter produced by the bruises of the omentum, or other viscera, in the efforts of parturition, rather than by purulent matter, the consequence of suppuration. The pulse is generally about 120 when in bed and in the morning; and is increased to 134, or more, when the patient sits up, or in the evening paroxysm. The pulse of all very weak patients increases in frequency when they sit up; because the expenditure of sensorial power necessary to preserve an erect posture deducts so much from their general strength; and hence the pulse becomes weaker, and in consequence quicker. See Sect. XII. 1. 4. In this fever time must be allowed for the absorption of the matter. Very large and repeated quantities of the bark, by preventing sufficient food from being taken, as bread, and wine, and water, I have thought has much injured the patient; for the bark is not here given as in intermittent fevers to prevent the paroxysm, but simply to strengthen the patient by increasing the power of digestion. About two ounces of decoction of bark, with four drops of laudanum, and a dram of sweet spirit of vitriol, once in six hours, and a glass of wine between those times, with panada, or other food, I have thought of most advantage, with a small blister occasionally. Where not only the stomach but also the bowels are much distended with air, so as to sound on striking them with the fingers, the case is always dangerous, generally hopeless; which is more so in proportion to the quickness of the pulse. Where the bowels are distended two drops of oil of cinnamon should be given in the panada three or four times a day. 17. _Febris a sphacelo._ Fever from mortification. This fever from absorption of putrid matter is of the inirritative or typhus kind. See the preceding article. M. M. Opium and the bark are frequently given in too great quantity, so as to induce consequent debility, and to oppress the power of digestion. * * * * * ORDO I. _Increased Sensation._ GENUS VII. _With increased Action of the Organs of Sense._ SPECIES. 1. _Delirium febrile._ Paraphrosyne. The ideas in delirium consist of those excited by the sensation of pleasure or pain, which precedes them, and the trains of other ideas associated with these, and not of those excited by external irritations or by voluntary exertion. Hence the patients do not know the room which they inhabit, or the people who surround them; nor have they any voluntary exertion, where the delirium is complete; so that their efforts in walking about a room or rising from their bed are unsteady, and produced by their catenations with the immediate affections of pleasure or pain. See Section XXXIII. 1. 4. By the above circumstances it is distinguished from madness, in which the patients well know the persons of their acquaintance, and the place where they are; and perform all the voluntary actions with steadiness and determination. See Sect. XXXIV. 2. 2. Delirium is sometimes less complete, and then a new face and louder voice stimulate the patient to attend to them for a few moments; and then they relapse again into perfect delirium. At other times a delirium affects but one sense, and the person thinks he sees things which do not exist; and is at the same time sensible to the questions which are asked him, and to the taste of the food which is offered to him. This partial delirium is termed an hallucination of the disordered organ; and may probably arise from the origin of one nerve of sense being more liable to inflammation than the others; that is, an exuberance of the sensorial power of sensation may affect it; which is therefore thrown into action by slighter sensitive catenations, without being obedient to external stimulus, or to the power of volition. The perpetual flow of ideas in delirium is owing to the same circumstance, as of those in our dreams; namely, to the defect or paralysis of the voluntary power; as in hemiplagia, when one side of the body is paralytic, and thus expends less of the sensorial power, the limbs on the other side are in constant motion from the exuberance of it. Whence less sensorial power is exhausted in delirium, than at other times, as well as in sleep; and hence in fevers with great debility, it is perhaps, as well as the stupor, rather a favourable circumstance; and when removed by numerous blisters, the death of the patient often follows the recovery of his understanding. See Class I. 2. 5. 6. and I. 2. 5. 10. Delirium in diseases from inirritability is sometimes preceded by a propensity to surprise. See Class I. 1. 5. 11. M. M. Fomentations of the shaved head for an hour repeatedly. A blister on the head. Rising from bed. Wine and opium, and sometimes venesection in small quantity by cupping, if the strength of the arterial system will allow it. 2. _Delirium maniacale._ Maniacal delirium. There is another kind of delirium, described in Sect. XXXIII. 1. 4. which has the increase of pleasureable or painful sensation for its cause, without any diminution of the other sensorial powers; but as this excites the patient to the exertion of voluntary actions, for the purpose of obtaining the object of his pleasureable ideas, or avoiding the object of his painful ones, such as perpetual prayer, when it is of the religious kind, it belongs to the insanities described in Class III. 1. 2. 1, and is more properly termed hallucinatio maniacalis. 3. _Dilirium ebrietatis._ The drunken delirium is in nothing different from the delirium attending fevers except in its cause, as from alcohol, or other poisons. When it is attended with an apoplectic stupor, the pulse is generally low; and venesection I believe sometimes destroys those, who would otherwise have recovered in a few hours. M. M. Diluting liquids. An emetic. 4. _Somnium._ Dreams constitute the most complete kind of delirium. As in these no external irritations are attended to, and the power of volition is entirely suspended; so that the sensations of pleasure and pain, with their associations, alone excite the endless trains of our sleeping ideas; as explained in Sect. XVIII. on Sleep. 5. _Hallucinatio visûs._ Deception of sight. These visual hallucinations are perpetual in our dreams; and sometimes precede general delirium in fevers; and sometimes belong to reverie, and to insanity. See Class III. 1. 2. 1. and 2. and must be treated accordingly. Other kinds of visual hallucinations occur by moon-light; when objects are not seen so distinctly as to produce the usual ideas associated with them, but appear to us exactly as they are seen. Thus the trunk of a tree appears a flat surface, instead of a cylinder as by day, and we are deceived and alarmed by seeing things as they really are seen. See Berkley on Vision. 6. _Hallucinatio auditûs._ Auricular deception frequently occurs in dreams, and sometimes precedes general delirium in fevers; and sometimes belongs to vertigo, and to reverie, and to insanity. See Sect. XX. 7. and Class III. 1. 2. 1. and 2. 7. _Rubor a calore._ The blush from heat is occasioned by the increased action of the cutaneous vessels in consequence of the increased sensation of heat. See Class I. 1. 2. 1. and 3. 8. _Rubor jucunditatis._ The blush of joy is owing to the increased action of the capillary arteries, along with that of every moving vessel in the body, from the increase of pleasurable sensation. 9. _Priapismus amatorius._ Amatorial priapism. The blood is poured into the cells of the corpora cavernosa much faster than it can be reabsorbed by the vena penis, owing in this case to the pleasurable sensation of love increasing the arterial action. See Class I. 1. 4. 6. 10. _Distentio mamularum._ The teats of female animals, when they give suck, become rigid and erected, in the same manner as in the last article, from the pleasurable sensation of the love of the mother to her offspring. Whence the teat may properly be called an organ of sense. The nipples of men do the same when rubbed with the hand. See Class I. 1. 4. 7. * * * * * ORDO II. _Decreased Sensation._ GENUS I. _Of the General System._ SPECIES. 1. _Stultitia insensibilis._ Folly from insensibility. The pleasure or pain generated in the system is not sufficient to promote the usual activity either of the sensual or muscular fibres. 2. _Tædium vitæ._ Ennui. Irksomeness of life. The pain of laziness has been thought by some philosophers to be that principle of action, which has excited all our industry, and distinguished mankind from the brutes of the field. It is certain that, where the ennui exists, it is relieved by the exertions of our minds or bodies, as all other painful sensations are relieved; but it depends much upon our early habits, whether we become patient of laziness, or inclined to activity, during the remainder of our lives, as other animals do not appear to be affected with this malady; which is perhaps left owing to deficiency of pleasurable sensation, than to the superabundancy of voluntary power, which occasions pain in the muscles by its accumulation; as appears from the perpetual motions of a squirrel confined in a cage. 3. _Paresis sensitiva._ Weakness of the whole system from insensibility. * * * * * ORDO II. _Decreased Sensation._ GENUS II. _Of Particular Organs._ SPECIES. 1. _Anorexia._ Want of appetite. Some elderly people, and those debilitated by fermented liquors, are liable to lose their appetite for animal food; which is probably in part owing to the deficiency of gastric acid, as well as to the general decay of the system: elderly people will go on years without animal food; but inebriates soon sink, when their digestion becomes so far impaired. Want of appetite is sometimes produced by the putrid matter from many decaying teeth being perpetually mixed with the saliva, and thence affecting the organ of taste, and greatly injuring the digestion. M. M. Fine charcoal powder diffused in warm water held in the mouth frequently in a day, as in Class I. 2. 4. 12. or solution of alum in water. Extract the decayed teeth. An emetic. A blister. Chalybeates. Vitriolic acid. Bile of an ox inspissated, and made into pills; 20 grains to be taken before dinner and supper. Opium half a grain twice a day. All the strength we possess is ultimately derived from the food, which we are able to digest; whence a total debility of the system frequently follows the want of appetite, and of the power of digestion. Some young ladies I have observed to fall into this general debility, so as but just to be able to walk about; which I have sometimes ascribed to their voluntary fasting, when they believed themselves too plump; and who have thus lost both their health and beauty by too great abstinence, which could never be restored. I have seen other cases of what may be termed anorexia epileptica, in which a total loss of appetite, and of the power of digestion, suddenly occurred along with epileptic fits. Miss B. a girl about eighteen, apparently very healthy, and rather plump, was seized with fits, which were at first called hysterical; they occurred at the end of menstruation, and returned very frequently with total loss of appetite. She was relieved by venesection, blisters, and opiates; her strength diminished, and after some returns of the fits, she took to her bed, and has survived 15 or 20 years; she has in general eaten half a potato a day, and seldom speaks, but retains her senses, and had many years occasional returns of convulsion. I have seen two similar cases, where the anorexia, or want of appetite, was in less degree; and but just so much food could be digested, as supplied them with sufficient strength to keep from the bed or sofa for half the day. As well as I can recollect, all these patients were attended with weak pulse, and cold pale skin; and received benefit by opium, from a quarter of a grain to a grain four times a day. See Class III. 1. 1. 7. and III. 1. 2. 1. and III. 1. 2. 20. 2. _Adipsia._ Want of thirst. Several of the inferior people, as farmers wives, have a habit of not drinking with their dinner at all, or only take a spoonful or two of ale after it. I have frequently observed these to labour under bad digestion, and debility in consequence; which I have ascribed to the too great stimulus of solid food undiluted, destroying in process of time the irritability of the stomach. 3. _Impotentia_ (agenesia). Impotency much seldomer happens to the male sex than sterility to the female sex. Sometimes a temporary impotence occurs from bashfulness, or the interference of some voluntary exertion in the production of an effect, which should be performed alone by pleasurable sensation. One, who was soon to be married to a lady of superior condition to his own, expressed fear of not succeeding on the wedding night; he was advised to take a grain of opium before he went to bed, and to accustom himself to sleep with a woman previously, but not to enjoy her, to take off his bashfulness; which succeeded to his wish. M. M. Chalybeates. Opium. Bark. Tincture of cantharides. 4. _Sterilitas._ Barrenness. One of the ancient medical writers asserts, that the female sex become pregnant with most certainty at or near the time of menstruation. This is not improbable, since these monthly periods seem to referable the monthly venereal orgasm of some female quadrupeds, which become pregnant at those times only; and hence the computation of pregnancy is not often erroneous, though taken from the last menstruation. See Section XXXVI. 2. 3. M. M. Opium a grain every night. Chalybeates in very small doses. Bark. Sea-bathing. 5. _Insensibilitas artuum._ As in some paralytic limbs. A great insensibility sometimes accompanies the torpor of the skin in cold fits of agues. Some parts have retained the sense of heat, but not the sense of touch. See Sect. XVI. 6. M. M. Friction with flannel. A blister. Warmth. 6. _Dysuria insensitiva._ Insensibility of the bladder. A difficulty or total inability to make water attends some fevers with great debility, owing to the insensibility or inirritability of the bladder. This is a dangerous but not always a fatal symptom. M. M. Draw off the water with a catheter. Assist the patient in the exclusion of it by compressing the lower parts of the abdomen with the hands. Wine two ounces, Peruvian bark one dram in decoction, every three hours alternately. Balsam of copaiva. Oil of almonds, with as much camphor as can be dissolved in it, applied as a liniment rubbed on the region of the bladder and perinæum, and repeated every four hours, was used in this disease with success by Mr. Latham. Med. Comment. 1791, p. 213. 7. _Accumulatio alvina._ An accumulation of feces in the rectum, occasioned by the torpor, or insensibility, of that bowel. But as liquids pass by these accumulations, it differs from the constipatio alvi, which is owing to too great absorption of the alimentary canal. Old milk, and especially when boiled, is liable to induce this kind of costiveness in some grown persons; which is probably owing to their not possessing sufficient gastric acid to curdle and digest it; for as both these processes require gastric acid, it follows, that a greater quantity of it is necessary, than in the digestion of other aliments, which do not previously require being curdled. This ill digested milk not sufficiently stimulating the rectum, remains till it becomes a too solid mass. On this account milk seldom agrees with those, who are subject to piles, by inducing costiveness and large stools. M. M. Extract the hardened scybala by means of a marrow-spoon; or by a piece of wire, or of whale-bone bent into a bow, and introduced. Injections of oil. Castor oil, or oil of almonds, taken by the mouth. A large clyster of smoak of tobacco. Six grains of rhubarb taken every night for many months. Aloes. An endeavour to establish a habit of evacuation at a certain hour daily. See Class I. 1. 3. 5. * * * * * ORDO III. _Retrograde Sensitive Motions._ GENUS I. _Of Excretory Ducts._ The retrograde action of the oesophagus in ruminating animals, when they bring up the food from their first stomach for the purpose of a second mastication of it, may probably be caused by agreeable sensation; similar to that which induces them to swallow it both before and after this second mastication; and then this retrograde action, properly belongs to this place, and is erroneously put at the head of the order of irritative retrograde motions. Class I. 3. 1. 1. SPECIES. 1. _Ureterum motus retrogressus._ When a stone has advanced into the ureter from the pelvis of the kidney, it is sometimes liable to be returned by the retrograde motion of that canal, and the patient obtains fallacious ease, till the stone is again pushed into the ureter. 2. _Urethræ motus retrogressus._ There have been instances of bougies being carried up the urethra into the bladder most probably by an inverted motion of this canal; for which some have undergone an operation similar to that for the extraction of a stone. A case is related in some medical publication, in which a catgut bougie was carried into the bladder, and after remaining many weeks, was voided piece-meal in a semi-dissolved state. Another case is related of a French officer, who used a leaden bougie; which at length found its way into the bladder, and was, by injecting crude mercury, amalgamated and voided. In the same manner the infection from a simple gonorrhoea is probably carried further along the course of the urethra; and small stones frequently descend some way into the urethra, and are again carried up into the bladder by the inverted action of this canal. 3. _Ductus choledochi motus retrogressus._ The concretions of bile, called gall-stones, frequently enter the bile-duct, and give violent pain for some hours; and return again into the gall-bladder, by the retrograde action of this duct. May not oil be carried up this duct, when a gall-stone gives great pain, by its retrograde spasmodic action? See Class I. 1. 3. 8. M. M. Opium a grain and half. * * * * * _The Orders and Genera of the Third Class of Diseases._ * * * * * CLASS III. DISEASES OF VOLITION. ORDO I. _Increased Volition._ GENERA. 1. With increased actions of the muscles. 2. With increased actions of the organs of sense. ORDO II. _Decreased Volition._ GENERA. 1. With decreased actions of the muscles. 2. With decreased actions of the organs of sense. * * * * * _The Orders, Genera, and Species, of the Third Class of Diseases._ * * * * * CLASS III. DISEASES OF VOLITION. ORDO I. _Increased Volition._ GENUS I. _With Increased Actions of the Muscles._ SPECIES. 1. _Jactitatio._ Restlessness. 2. _Tremor febrilis._ Febrile trembling. 3. _Clamor._ Screaming. 4. _Risus._ Laughter. 5. _Convulsio._ Convulsion. ---- _debilis._ ---- weak. 6. ---- _dolorifica._ ---- painful. 7. _Epilepsia._ Epilepsy. 8. ---- _dolorifica._ ---- painful. 9. _Somnambulismus._ Sleep-walking. 10. _Asthma convulsivum._ Asthma convulsive. 11. ---- _dolorificum._ ---- painful. 12. _Stridor dentium._ Gnashing of the teeth. 13. _Tetanus trismus._ Cramp of the jaw. 14. ---- _dolorificus._ ---- painful. 15. _Hydrophobia._ Dread of water. GENUS II. _With increased Actions of the Organs of Sense._ SPECIES. 1. _Mania mutabilis._ Mutable madness. 2. _Studium inane._ Reverie. 3. _Vigilia._ Watchfulness. 4. _Erotomania._ Sentimental love. 5. _Amor sui._ Vanity. 6. _Nostalgia._ Desire of home. 7. _Spes religiosa._ Superstitious hope. 8. _Superbia stemmatis._ Pride of family. 9. _Ambitio._ Ambition. 10. _Mæror._ Grief. 11. _Tædium vitæ._ Irksomeness of life. 12. _Desiderium pulchritudinis._ Loss of beauty. 13. _Paupertatis timor._ Fear of poverty. 14. _Lethi timor._ ---- of death. 15. _Orci timor._ ---- of hell. 16. _Satyriasis._ Lust. 17. _Ira._ Anger. 18. _Rabies._ Rage. 19. _Citta._ Depraved appetite. 20. _Cacositia._ Aversion to food. 21. _Syphilis imaginaria._ Imaginary pox. 22. _Psora imaginaria._ ---- itch. 23. _Tabes imaginaria._ ---- tabes. 24. _Sympathia aliena._ Pity. 25. _Educatio heroica._ Heroic education. ORDO II. _Decreased Volition._ GENUS I. _With decreased Actions of the Muscles._ SPECIES. 1. _Lassitudo._ Fatigue. 2. _Vacillatio senilis._ See-saw of old age. 3. _Tremor senilis._ Tremor of old age. 4. _Brachiorum paralysis._ Palsy of the arms. 5. _Raucedo paralytica._ Paralytic hoarseness. 6. _Vesicæ urinariæ paralysis._ Palsy of the bladder. 7. _Recti paralysis._ Palsy of the rectum. 8. _Paresis voluntaria._ Voluntary debility. 9. _Catalepsis._ Catalepsy. 10. _Hemiplegia._ Palsy of one side. 11. _Paraplegia._ Palsy of the lower limbs. 12. _Somnus._ Sleep. 13. _Incubus._ Night-mare. 14. _Lethargus._ Lethargy. 15. _Syncope epileptica._ Epileptic fainting. 16. _Apoplexia._ Apoplexy. 17. _Mors a frigore._ Death from cold. GENUS II. _With decreased Actions of the Organs of Sense._ SPECIES. 1. _Recollectionis jactura._ Loss of recollection. 2. _Stultitia voluntaria._ Voluntary folly. 3. _Credulitas._ Credulity. * * * * * CLASS III. DISEASES OF VOLITION. ORDO I. _Increased Volition._ GENUS I. _Increased Actions of the Muscles._ We now step forward to consider the diseases of volition, that superior faculty of the sensorium, which gives us the power of reason, and by its facility of action distinguishes mankind from brute animals; which has effected all that is great in the world, and superimposed the works of art on the situations of nature. Pain is introduced into the system either by excess or defect of the action of the part. (Sect. IV. 5.) Both which circumstances seem to originate from the accumulation of sensorial power in the affected organ. Thus when the skin is exposed to great cold, the activity of the cutaneous vessels is diminished, and in consequence an accumulation of sensorial power obtains in them, because they are usually excited into incessant motion by the stimulus of heat, as explained in Sect. XII. 5. 2. Contrarywise, when the vessels of the skin are exposed to great heat, an excess of sensorial power is also produced in them, which is derived thither by the increase of stimulus above what is natural. This accounts for the relief which is received in all kinds of pain by any violent exertions of our muscles or organs of sense; which may thus be in part ascribed to the exhaustion of the sensorial power by such exertions. But this relief is in many cases so instantaneous, that it seems nevertheless probable, that it is also in part owing to the different manner of progression of the two sensorial powers of sensation and volition; one of them commencing at some extremity of the sensorium, and being propagated towards the central parts of it; and the other commencing in the central parts of the sensorium, and being propagated towards the extremities of it; as mentioned in Sect. XI. 2. 1. These violent voluntary exertions of our muscles or ideas to relieve the sensation of pain constitute convulsions and madness; and are distinguished from the muscular actions owing to increased sensation, as in sneezing, or coughing, or parturition, or ejectio feminis, because they do not contribute to dislodge the cause, but only to prevent the sensation of it. In two cases of parturition, both of young women with their first child, I have seen general convulsions occur from excess of voluntary exertion, as above described, instead of the actions of particular muscles, which ought to have been excited by sensation for the exclusion of the fetus. They both became insensible, and died after some hours; from one of them the fetus was extracted in vain. I have heard also of general convulsions being excited instead of the actions of the musculi acceleratores in the ejectio feminis, which terminated fatally. See Class III. 1. 1. 7. These violent exertions are most frequently excited in consequence of those pains, which originate from defect of the action of the part. See Sect. XXXIV. 1. and 2. The pains from excess and defect of the action of the part are distinguishable from each other by the former being attended with increase of heat in the pained part, or of the whole body; while the latter not only exist without increase of heat in the pained part, but are generally attended with coldness of the extremities of the body. As soon as these violent actions of our muscular or sensual fibres for the purpose of relieving pain cease to be exerted, the pain recurs; whence the reciprocal contraction and relaxation of the muscles in convulsion, and the intervals of madness. Otherwise these violent exertions continue, till so great a part of the sensorial power is exhausted, that no more of it is excitable by the faculty of volition; and a temporary apoplexy succeeds, with snoring as in profound sleep; which so generally terminates epileptic fits. When these voluntary exertions become so connected with certain disagreeable sensations, or with irritations, that the effort of the will cannot restrain them, they can no longer in common language be termed voluntary; but nevertheless belong to this class, as they are produced by excess of volition, and may still not improperly be called depraved voluntary actions. See Sect. XXXIV. 1. where many motions in common language termed involuntary are shewn to depend on excess of volition. When these exertions from excess of volition, which in common language are termed involuntary motions, either of mind or body, are perpetually exerted in weak constitutions, the pulse becomes quick; which is occasioned by the too great expenditure of the sensorial power in these unceasing modes of activity. In the same manner as in very weak people in fevers, the pulse sometimes increases in frequency to 140 strokes in a minute, when the patients stand up or endeavour to walk; and subsides to 110, when they lie down again in their beds. Whence it appears, that when a very quick pulse accompanies convulsion or insanity, it simply indicates the weakness of the patient; that is, that the expenditure of sensorial power is too great for the supply of it. But if the strength of the patient is not previously exhausted, the exertions of the muscles are attended with temporary increase of circulation, the reciprocal swellings and elongations of their bellies push forwards the arterial blood, and promote the absorption of the venous blood; whence a temporary increase of secretion and of heat, and a stronger pulse. SPECIES. 1. _Jactitatio._ Restlessness. There is one kind of restlessness attending fevers, which consists in a frequent change of posture to relieve the uneasiness of the pressure of one part of the body upon another, when the sensibility of the system, or of some parts of it, is increased by inflammation, as in the lumbago; which may sometimes be distinguished in its early stage by the incessant desire of the patient to turn himself in bed. But there is another restlessness, which approaches towards writhing or contortions of the body, which is a voluntary effort to relieve pain; and may be esteemed a slighter kind of convulsion, not totally unrestrainable by opposite or counteracting volitions. M. M. A blister. Opium. Warm bath. 2. _Tremor febrilis._ Reciprocal convulsions of the subcutaneous muscles, originating from the pain of the sense of heat, owing to defect of its usual stimulus, and consequent accumulation of sensorial power in it. The actual deficiency of heat may exist in one part of the body, and the pain of cold be felt most vividly in some other part associated with it by sensitive sympathy. So a chillness down the back is first attended to in ague-fits, though the disease perhaps commences with the torpor and consequent coldness of some internal viscus. But in whatever part of the system the defect of heat exists, or the sensation of it, the convulsions of the subcutaneous muscles exerted to relieve it are very general; and, if the pain is still greater, a chattering of the teeth is added, the more suddenly to exhaust the sensorial power, and because the teeth are very sensible to cold. These convulsive motions are nevertheless restrainable by violent voluntary counteraction; and as their intervals are owing to the pain of cold being for a time relieved by their exertion, they may be compared to laughter, except that there is no interval of pleasure preceding each moment of pain in this as in the latter. M. M. See I. 2. 2. 1. 3. _Clamor._ Screaming from pain. The talkative animals, as dogs, and swine, and children, scream most, when they are in pain, and even from fear; as they have used this kind of exertion from their birth most frequently and most forcibly; and can therefore sooner exhaust the accumulation of sensorial power in the affected muscular or sensual organs by this mode of exertion; as described in Sect. XXXIV. 1. 3. This facility of relieving pain by screaming is the source of laughter, as explained below. 4. _Risus._ The pleasurable sensations, which occasion laughter, are perpetually passing into the bounds of pain; for pleasure and pain are often produced by different degrees of the same stimulus; as warmth, light, aromatic or volatile odours, become painful by their excess; and the tickling on the soles of the feet in children is a painful sensation at the very time it produces laughter. When the pleasurable ideas, which excite us to laugh, pass into pain, we use some exertion, as a scream, to relieve the pain, but soon stop it again, as we are unwilling to lose the pleasure; and thus we repeatedly begin to scream, and stop again alternately. So that in laughing there are three stages, first of pleasure, then pain, then an exertion to relieve that pain. See Sect. XXXIV. 1. 3. Every one has been in a situation, where some ludicrous circumstance has excited him to laugh; and at the same time a sense of decorum has forbid the exertion of these interrupted screams; and then the pain has become so violent, as to occasion him to use some other great action, as biting his tongue, and pinching himself, in lieu of the reiterated screams which constitute laughter. 5. _Convulsio._ Convulsion. When the pains from defect or excess of motion are more distressing than those already described, and are not relievable by such partial exertions, as in screaming, or laughter, more general convulsions occur; which vary perhaps according to the situation of the pained part, or to some previous associations formed by the early habits of life. When these convulsive motions bend the body forwards, they are termed emprosthotonoi; when they bend it backward, they are termed opisthotonoi. They frequently succeed each other, but the opisthotonoi are generally more violent; as the muscles, which erect the body, and keep it erect, are naturally in more constant and more forcible action than their antagonists. The causes of convulsion are very numerous, as from toothing in children, from worms or acidity in their bowels, from eruption of the distinct small-pox, and lastly, from breathing too long the air of an unventilated bed-room. Sir G. Baker, in the Transactions of the College, described this disease, and detected its cause; where many children in an orphan-house were crowded together in one chamber without a chimney, and were almost all of them affected with convulsion; in the hospital at Dublin, many died of convulsions before the real cause was understood. See Dr. Beddoes's Guide to Self-preservation. In a large family, which I attended, where many female servants slept in one room, which they had contrived to render inaccessible to every blast of air; I saw four who were thus seized with convulsions, and who were believed to have been affected by sympathy from the first who fell ill. They were removed into more airy apartments, but were some weeks before they all regained their perfect health. Convulsion is distinguished from epilepsy, as the patient does not intirely lose all perception during the paroxysm. Which only shews, that a less exhaustion of sensorial power renders tolerable the pains which cause convulsion, than those which cause epilepsy. The hysteric convulsions are distinguished from those, owing to other causes, by the presence of the expectation of death, which precedes and succeeds them, and generally by a flow of pale urine; these convulsions do not constantly attend the hysteric disease, but are occasionally superinduced by the disagreeable sensation arising from the torpor or inversion of a part of the alimentary canal. Whence the convulsion of laughter is frequently sufficient to restrain these hysteric pains, which accounts for the fits of laughter frequently attendant on this disease. M. M. To remove the peculiar pain which excites the convulsions. Venesection. An emetic. A cathartic with calomel. Warm-bath. Opium in large quantities, beginning with smaller ones. Mercurial frictions. Electricity. Cold-bath in the paroxysm; or cold aspersion. See Memoirs of Med. Society, Lon. V. 3. p. 147. a paper by Dr. Currie. _Convulsio debilis._ The convulsions of dying animals, as of those which are bleeding to death in the slaughter-house, are an effort to relieve painful sensation, either of the wound which occasions their death, or of faintness from want of due distention of the blood-vessels. Similar to this in a less degree is the subsultus tendinum, or starting of the tendons, in fevers with debility; these actions of the muscles are too weak to move the limb, but the belly of the acting muscles is seen to swell, and the tendon to be stretched. These weak convulsions, as they are occasioned by the disagreeable sensation of faintness from inanition, are symptoms of great general debility, and thence frequently precede the general convulsions of the act of dying. See a case of convulsion of a muscle of the arm, and of the fore-arm, without moving the bones to which they were attached, Sect. XVII. 1. 8. See twitchings of the face, Class IV. 1. 3. 2. 6. _Convulsio dolorifica._ Raphania. Painful convulsion. In this disease the muscles of the arms and legs are exerted to relieve the pains left after the rheumatism in young and delicate people; it recurs once or twice a-day, and has been mistaken for the chorea, or St. Vitus's dance; but differs from it, as the undue motions in that disease only occur, when the patient endeavours to exert the natural ones; are not attended with pain; and cease, when he lies down without trying to move: the chorea, or dance of St. Vitus, is often introduced by the itch, this by the rheumatism. It has also been improperly called nervous rheumatism; but is distinguished from rheumatism, as the pains recur by periods once or twice a day; whereas in the chronic rheumatism they only occur on moving the affected muscles. And by the warmth of a bed the pains of the chronic rheumatism are increased, as the muscles or membranes then become more sensible to the stimulus of the extraneous mucaginous material deposited under them. Whereas the pains of the raphania, or painful convulsion, commence with coldness of the part, or of the extremities. See Rheumatismus chronicus, Class I. 1. 3. 12. The pains which accompany the contractions of the muscles in this disease, seem to arise from the too great violence of those contractions, as happens in the cramp of the calf of the leg; from which they differ in those being fixed, and these being reiterated contractions. Thus these convulsions are generally of the lower limbs, and recur at periodical times from some uneasy sensation from defect of action, like other periodic diseases; and the convulsions of the limbs relieve the original uneasy painful sensation, and then produce a greater pain from their own too vehement contractions. There is however another way of accounting for these pains, when they succeed the acute rheumatism; and that is by the coagulable lymph, which may be left still unabsorbed on the membranes; and which may be in too small quantity to affect them with pain in common muscular exertions, but may produce great pain, when the bellies of the muscles swell to a larger bulk in violent action. M. M. Venesection. Calomel. Opium. Bark. One grain of calomel and one of opium for ten successive nights. A bandage spread with emplastrum de minio put tight on the affected part. 7. _Epilepsia_ is originally induced, like other convulsions, by a voluntary exertion to relieve some pain. This pain is most frequently about the pit of the stomach, or termination of the bile-duct; and in some cases the torpor of the stomach, which probably occasioned the epileptic fits, remains afterwards, and produces a chronical anorexia; of which a case is related in Class II. 2. 2. 1. There are instances of its beginning in the heel, of which a case is published by Dr. Short, in the Med. Essays, Edinb. I once saw a child about ten years old, who frequently fell down in convulsions, as she was running about in play; on examination a wart was found on one ancle, which was ragged and inflamed; which was directed to be cut off, and the fits never recurred. When epilepsy first commences, the patients are liable to utter one scream before they fall down; afterwards the convulsions so immediately follow the pain, which occasions them, that the patient does not recollect or seem sensible of the preceding pain. Thus in laughter, when it is not excessive, a person is not conscious of the pain, which so often recurs, and causes the successive screams or exertions of laughter, which give a temporary relief to it. Epileptic fits frequently recur in sleep from the increase of sensibility at that time, explained in Sect. XVIII. 14. In two such cases, both of young women, one grain of opium given at night, and continued many months, had success; in one of them the opium was omitted twice at different times, and the fit recurred on both the nights. In the more violent case, described in Sect. XVIII. 15, opium had no effect. Epileptic fits generally commence with setting the teeth, by which means the tongue is frequently wounded; and with rolling the eyeballs in every kind of direction; for the muscles which suspend the jaw, as well as those which move the eyes, are in perpetual motion during our waking hours; and yet continue subservient to volition; hence their more facile and forcible actions for the purpose of relieving pain by the exhaustion of sensorial power. See Section XXXIV. 1. 4. Epileptic convulsions are not attended with the fear of death, as in the hysteric disease, and the urine is of a straw colour. However it must be noted, that the disagreeable sensations in hysteric diseases sometimes are the cause of true epileptic convulsions, of syncope, and of madness. The pain, which occasions some fits of epilepsy, is felt for a time in a distant part of the system, as in a toe or heel; and is said by the patient gradually to ascend to the head, before the general convulsions commence. This ascending sensation has been called aura epileptica, and is said to have been prevented from affecting the head by a tight bandage round the limb. In this malady the pain, probably of some torpid membrane, or diseased tendon, is at first only so great as to induce slight spasms of the muscular fibres in its vicinity; which slight spasms cease on the numbness introduced by a tight bandage; when no bandage is applied, the pain gradually increases, till generally convulsions are exerted to relieve it. The course of a lymphatic, as when poisonous matter is absorbed; or of a nerve, as in the sciatica, may, by the sympathy existing between their extremities and origins, give an idea of the ascent of an aura or vapour. In difficult parturition it sometimes happens, that general convulsions are excited to relieve the pain of labour, instead of the exertions of those muscles of the abdomen and diaphragm, which ought to forward the exclusion of the child. See Class III. 1. 1. That is, instead of the particular muscular actions, which ought to be excited by sensation to remove the offending cause, general convulsions are produced by the power of volition, which still the pain, as in common epilepsy, without removing the cause; and, as the parturition is not thus promoted, the convulsions continue, till the sensorial power is totally exhausted, that is, till death. In patients afflicted with epilepsy from other causes, I have seen the most violent convulsions recur frequently during pregnancy without miscarriage, as they did not tend to forward the exclusion of the fetus. M. M. Venesection. A large dose of opium. Delivery. The later in life epileptic fits are first experienced, the more dangerous they may be esteemed in general; as in these cases the cause has generally been acquired by the habits of the patient, or by the decay of some part, and is thus probably in an increasing state. Whereas in children the changes in the system, as they advance to puberty, sometimes removes the cause. So in toothing, fits of convulsion with stupor frequently occur, and cease when the tooth advances; but this is not to be expected in advanced life. Sir ----, about sixty years of age, had only three teeth left in his upper jaw, a canine tooth, and one on each side of it. He was seized with epileptic fits, with pain commencing in these teeth. He was urged to have them extracted, which he delayed too long, till the fits were become habitual, and then had them extracted in vain, and in a few months sunk under the disease. Mr. F----, who had lived intemperately, and had been occasionally affected with the gout, was suddenly seized with epileptic fits; the convulsions were succeeded by apoplectic snoring; from which he was, in about 20 minutes, disturbed by fresh convulsions, and had continued in this situation above four-and-twenty hours. About eight ounces of blood were then taken from him; and after having observed, that the apoplectic's torpor continued about 20 minutes, I directed him to be forcibly raised up in bed, after he had thus lain about fifteen minutes, to gain an interval between the termination of the sleep, and the renovation of convulsion. In this interval he was induced to swallow forty drops of laudanum. Twenty more were given him in the same manner in about half an hour, both which evidently shortened the convulsion fits, and the consequent stupor; he then took thirty more drops, which for the present removed the fits. He became rather insane the next day, and after about three more days lost the insanity, and recovered his usual state of health. The case mentioned in Sect. XXVII. 2. where the patient was left after epileptic fits with a suffusion of blood beneath the tunica adjunctiva of the eye, was in almost every respect similar to the preceding, and submitted to the same treatment. Both of them suffered frequent relapses, which were relieved by the same means, and at length perished, I believe, by the epileptic fits. In those patients, who have not been subject to epilepsy before they have arrived to about forty years of age, and who have been intemperate in respect to spirituous potation, I have been induced to believe, that the fits were occasioned by the pain of a diseased liver; and this became more probable in one of the above subjects, who had used means to repel eruptions on the face; and thus by some stimulant application had prevented an inflammation taking place on the skin of the face instead of on some part of the liver. Secondly, as in these cases insanity had repeatedly occurred, which could not be traced from an hereditary source; there is reason to believe, that this as well as the epileptic convulsions were caused by spirituous potation; and that this therefore is the original source both of epilepsy and of insanity in those families, which are afflicted with them. This idea however brings some consolation with it; as it may be inferred, that in a few sober generations these diseases may be eradicated, which otherwise destroy the family. M. M. Venesection. Opium. Bark. Steel. Arsenic. Opium one grain twice a day for years together. See the preceding article. 8. _Epilepsia dolorifica._ Painful epilepsy. In the common epilepsy the convulsions are immediately induced, as soon as the disagreeable sensation, which causes them, commences; but in this the pain continues long with cold extremities, gradually increasing for two or three hours, till at length convulsions or madness come on; which terminate the daily paroxysm, and cease themselves in a little time afterwards. This disease sometimes originates from a pain about the lower edge of the liver, sometimes in the temple, and sometimes in the pudendum; it recurs daily for five or six weeks, and then ceases for several months. The pain is owing to defect of action, that is, to the accumulation of sensorial power in the part, which probably sympathizes with some other part, as explained in Sect. XXXV. 2. XII. 5. 3. and Class II. 1. 1. 11. and IV. 2. 2. 3. It is the most painful malady that human nature is liable to!--See Sect. XXXIV. 1. 4. Mrs. C---- was seized every day about the same hour with violent pain on the right side of her bowels about the situation of the lower edge of the liver, without fever, which increased for an hour or two, till it became totally intolerable. After violent screaming she fell into convulsions, which terminated sometimes in fainting, with or without stertor, as in common epilepsy; at other times a tempory insanity supervened; which continued about half an hour, and the fit ceased. These paroxysms had returned daily for two or three weeks, and were at length removed by large doses of opium, like the fits of reverie or somnambulation. About half an hour before the expected return of the fit three or four grains of opium were exhibited, and then tincture of opium was given in warm brandy and water about 20 or 30 drops every half hour, till the eyes became somewhat inflamed, and the nose began to itch, and by the sharp movements of the patient, or quick speech, an evident intoxication appeared; and then it generally happened that the pain ceased. But the effects of this large dose of opium was succeeded by perpetual sickness and efforts to vomit, with great general debility all the succeeding day. The rationale of this temporary cure from the exhibition of opium and vinous spirit depends on the great expenditure of sensorial power in the increased actions of all the irritative motions, by the stimulus of such large quantities of opium and vinous spirit; together with the production of much sensation, and many movements of the organs of sense or ideas in consequence of that sensation; and lastly, even the motions of the arterial system become accelerated by this degree of intoxication, all which soon exhausted so much sensorial power as to relieve the pain; which would otherwise have caused convulsions or insanity, which are other means of expending sensorial power. The general debility on the succeeding day, and the particular debility of the stomach, attended in consequence with sickness and frequent efforts to vomit, were occasioned by the system having previously been so strongly stimulated, and those parts in particular on which the opium and wine more immediately acted. This sickness continued so many hours as to break the catenation of motions, which had daily reproduced the paroxysm; and thus it generally happened, that the whole disease ceased for some weeks or months from one great intoxication, a circumstance not easily to be explained on any other theory. The excess or defect of motion in any part of the system occasions the production of pain in that part, as in Sect. XII. 1. 6. This defect or excess of fibrous action is generally induced by excess or defect of the stimulus of objects external to the moving organ. But there is another source of excessive fibrous action, and consequent pain, which is from excess of volition, which is liable to affect those muscles, that have weak antagonists; as those which support the under jaw, and close the mouth in biting, and those of the calf of the leg; which are thus liable to fixed or painful contractions, as in trismus, or locked jaw, and in the cramp of the calf of the leg; and perhaps in some colics, as in that of Japan: these pains, from contraction arising from excess of volition in the part from the want of the counteraction of antagonist muscles, may give occasional cause to epileptic fits, and may be relieved in the same way, either by exciting irritative and sensitive motions by the stimulus of opium and wine; or by convulsions or insanity, as described above, which are only different methods of exhausting the general quantity of sensorial power. Considering the great resemblance between this kind of painful epilepsy and the colic of Japan, as described by Kemfer; and that that disease was said to be cured by acupuncture, or the prick of a needle; I directed some very thin steel needles to be made about three inches long, and of such a temper, that they would bend double rather than break; and wrapped wax thread over about half an inch of the blunt end for a handle. One of these needles, when the pain occurred, was pushed about an inch into the painful part, and the pain instantly ceased; but I was not certain, whether the fear of the patient, or the stimulus of the puncture, occasioned the cessation of pain; and as the paroxysm had continued some weeks, and was then declining, the experiment was not tried again. The disease is said to be very frequent in Japan, and its seat to be in the bowels, and that the acupuncture eliminates the air, which is supposed to distend the bowel. But though the aperture thus made is too small to admit of the eduction of air; yet as the stimulus of so small a puncture may either excite a torpid part into action, or cause a spasmodic one to cease to act; and lastly, as no injury could be likely to ensue from so small a perforation, I should be inclined at some future time to give this a fairer trial in similar circumstances. Another thing worth trial at the commencement of this deplorable disease would be electricity, by passing strong shocks through the painful part; which, whether the pain was owing to the inaction of that part, or of some other membrane associated with it, might stimulate them into exertion; or into inactivity, if owing to fixed painful contraction. And lastly, the cold bath, or aspersions with cold water on the affected part, according to the method of Dr. Currie in the Memoirs of a Med. Soc. London, V. iii. p. 147, might produce great effect at the commencement of the pain. Nevertheless opium duly administered, so as to precede the expected paroxysm, and in such doses, given by degrees, as to induce intoxication, is principally to be depended upon in this deplorable malady. To which should be added, that if venesection can be previously performed, even to but few ounces, the effect of the opium is much more certain; and still more so, if there be time to premise a brisk cathartic, or even an emetic. The effect of increased stimulus is so much greater after previous defect of stimulus; and this is still of greater advantage where the cause of the disease happens to consist in a material, which can be absorbed. See Art. IV. 2. 8. M. M. Venesection. An emetic. A cathartic. Warm bath. Opium a grain every half hour. Wine. Spirit of wine. If the patient becomes intoxicated by the above means, the fit ceases, and violent vomitings and debility succeed on the subsequent day, and prevent a return. Blisters or sinapisms on the small of the leg, taken off when they give much pain, are of use in slighter convulsions. Acupuncture. Electricity. Aspersion with cold water on the painful part. 9. _Somnambulismus._ Sleep-walking is a part of reverie, or studium inane, described in Sect. XIX. In this malady the patients have only the general appearance of being asleep in respect to their inattention to the stimulus of external objects, but, like the epilepsies above described, it consists in voluntary exertions to relieve pain. The muscles are subservient to the will, as appears by the patient's walking about, and sometimes doing the common offices of life. The ideas of the mind also are obedient to the will, because their discourse is consistent, though they answer imaginary questions. The irritative ideas of external objects continue in this malady, because the patients do not run against the furniture of the room; and when they apply their volition to their organs of sense, they become sensible of the objects they attend to, but not otherwise, as general sensation is destroyed by the violence of their voluntary exertions. At the same time the sensations of pleasure in consequence of ideas excited by volition are vividly experienced, and other ideas seem to be excited by these pleasurable sensations, as appears in the case of Master A. Sect. XXXIV. 3. 1. where a history of a hunting scene was voluntarily recalled, with all the pleasurable ideas which attended it. In melancholy madness the patient is employed in voluntarily exciting one idea, with those which are connected with it by voluntary associations only, but not so violently as to exclude the stimuli of external objects. In reverie variety of ideas are occasionally excited by volition, and those which are connected with them either by sensitive or voluntary associations, and that so violently as to exclude the stimuli of external objects. These two situations of our sensual motions, or ideas, resemble convulsion and epilepsy; as in the former the stimulus of external objects is still perceived, but not in the latter. Whence this disease, so far from being connected with sleep, though it has by universal mistake acquired its name from it, arises from excess of volition, and not from a suspension of it; and though, like other kinds of epilepsy, it often attacks the patients in their sleep, yet those two, whom I saw, were more frequently seized with it while awake, the sleep-walking being a part of the reverie. See Sect. XIX. and XXXIV. 3. and Class II. 1. 7. 4. and III. 1. 2. 18. M. M. Opium in large doses before the expected paroxysm. 10. _Asthma convulsivum._ The fits of convulsive asthma return at periods, and are attended with cold extremities, and so far resemble the access of an intermittent fever; but, as the lungs are not sensible to the pain of cold, a shivering does not succeed, but instead of it violent efforts of respiration; which have no tendency, as in the humoral asthma, to dislodge any offending material, but only to relieve the pain by exertion, like the shuddering in the beginning of ague-fits, as explained Class III. 1. 1. 2. The insensibility of the lungs to cold is observable on going into frosty air from a warm room; the hands and face become painfully cold, but no such sensation is excited in the lungs; which is another argument in favour of the existence of a peculiar set of nerves for the purpose of perceiving the universal fluid matter of heat, in which all things are immersed. See Sect. XIV. 6. Yet are the lungs nevertheless very sensible to the deficiency of oxygen in the atmosphere, as all people experience, when they go into a room crowded with company and candles, and complain, that it is so close, they can scarcely breathe; and the same in some hot days in summer. There are two diseases, which bear the name of asthma. The first is the torpor or inability of the minute vessels of the lungs, consisting of the terminations of the pulmonary and bronchial arteries and veins, and their attendant lymphatics; in this circumstance it resembles the difficulty of breathing, which attends cold bathing. If this continues long, a congestion of fluid in the air-cells succeeds, as the absorbent actions cease completely before the secerning ones; as explained in Class I. 1. 2. 3. And the coldness, which attends the inaction of these vessels, prevents the usual quantity of exhalation. Some fits cease before this congestion takes place, and in them no violent sweating nor any expuition of phlegm occurs. This is the humoral asthma, described at Class II. 1. 1. 7. The second kind of asthma consists in the convulsive actions in consequence of the disagreeable sensations thus induced; which in some fits of asthma are very great, as appears in the violent efforts to raise the ribs, and to depress the diaphragm, by lifting the shoulders. These, so long as they contribute to remove the cause of the disease, are not properly convulsions, but exertions immediately caused by sensation; but in this kind of asthma they are only efforts to relieve pain, and are frequently preceded by other epileptic convulsions. These two kinds of asthmas have so many resembling features, and are so frequently intermixed, that it often requires great attention to distinguish them; but as one of them is allied to anasarca, and the other to epilepsy, we shall acquire a clearer idea of them by comparing them with those disorders. A criterion of the humoral or hydropic asthma is, that it is relieved by copious sweats about the head and breast, which are to be ascribed to the sensitive exertions of the pulmonary vessels to relieve the pain occasioned by the anasarcous congestion in the air-cells; and which is effected by the increased absorption of the mucus, and its elimination by the retrograde action of those lymphatics of the skin, whose branches communicate with the pulmonary ones; and which partial sweats do not easily admit of any other explanation. See Class I. 3. 2. 8. Another criterion of it is, that it is generally attended with swelled legs, or other symptoms of anasarca. A criterion of the convulsive asthma may be had from the absence of these cold clammy sweats of the upper part of the body only, and from the patient having occasionally been subject to convulsions of the limbs, as in the common epilepsy. It may thus frequently happen, that in the humoral asthma some exertions of the lungs may occur, which may not contribute to discharge the anasarcous lymph, but may be efforts simply to relieve pain; besides those efforts, which produce the increased absorption and elimination of it; and thus we have a bodily disease resembling in this circumstance the reverie, in which both sensitive and voluntary motions are at the same time, or in succession, excited for the purpose of relieving pain. It may likewise sometimes happen, that the disagreeable sensation, occasioned by the congestion of lymph in the air-cells in the humoral or hydropic asthma, may induce voluntary convulsions of the respiratory organs only to relieve the pain, without any sensitive actions of the pulmonary absorbents to absorb and eliminate the congestion of serous fluid; and thus the same cause may occasionally induce either the humoral or convulsive asthma. The humoral asthma has but one remote cause, which is the torpor of the pulmonary vessels, like that which occurs on going into the cold bath; or the want of absorption of the pulmonary lymphatics to take up the lymph effused into the air-cell. Whereas the convulsive asthma, like other convulsions, or epilepsies, may be occasioned by pain in almost any remote part of the system. But in some of the adult patients in this disease, as in many epilepsies, I have suspected the remote cause to be a pain of the liver, or of the biliary ducts. The asthmas, which have been induced in consequence of the recess of eruptions, especially of the leprous kind, countenance this opinion. One lady I knew, who for many years laboured under an asthma, which ceased on her being afflicted with pain, swelling, and distortion of some of her large joints, which were esteemed gouty, but perhaps erroneously. And a young man, whom I saw yesterday, was seized with asthma on the retrocession, or ceasing of eruptions on his face. The convulsive asthma, as well as the hydropic, are more liable to return in hot weather; which may be occasioned by the less quantity of oxygen existing in a given quantity of warm air, than of cold, which can be taken into the lungs at one inspiration. They are both most liable to occur after the first sleep, which is therefore a general criterion of asthma. The cause of this is explained in Sect. XVIII. 15. and applies to both of them, as our sensibility to internal uneasy sensation increases during sleep. When children are gaining teeth, long before they appear, the pain of the gums often induces convulsions. This pain is relieved in some by sobbing and screaming; but in others a laborious respiration is exerted to relieve the pain; and this constitutes the true asthma convulsivum. In other children again general convulsions, or epileptic paroxysms, are induced for this purpose; which, like other epilepsies, become established by habit, and recur before the irritation has time to produce the painful sensation, which originally caused them. The asthma convulsivum is also sometimes induced by worms, or by acidity in the stomachs of children, and by other painful sensations in adults; in whom it is generally called nervous asthma, and is often joined with other epileptic symptoms. This asthma is distinguished from the peripneumony, and from the croup, by the presence of fever in the two latter. It is distinguished from the humoral asthma, as in that the patients are more liable to run to the cold air for relief, are more subject to cold extremities, and experience the returns of it more frequently after their first sleep. It is distinguished from the hydrops thoracis, as that has no intervals, and the patient sits constantly upright, and the breath is colder; and, where the pericardium is affected, the pulse is quick and unequal. See Hydrops Thoracis, I. 2. 3. 14. M. M. Venesection once. A cathartic with calomel once. Opium. Assafoetida. Warm bath. If the cause can be detected, as in toothing or worms, it should be removed. As this species of asthma is so liable to recur during sleep, like epileptic fits, as mentioned in Section XVIII. 15. there was reason to believe, that the respiration of an atmosphere mixed with hydrogen, or any other innocuous air, which might dilute the oxygen, would be useful in preventing the paroxysms by decreasing the sensibility of the system. This, I am informed by Dr. Beddoes, has been used with decided success by Dr. Ferriar. See Class II. 1. 1. 7. 11. _Asthma dolorificum._ Angina pectoris. The painful asthma was first described by Dr. Heberden in the Transactions of the College; its principal symptoms consist in a pain about the middle of the sternum, or rather lower, on every increase of pulmonary or muscular exertion, as in walking faster than usual, or going quick up a hill, or even up stairs; with great difficulty of breathing, so as to occasion the patient instantly to stop. A pain in the arms about the insertion of the tendon of the pectoral muscle generally attends, and a desire of resting by hanging on a door or branch of a tree by the arms is sometimes observed. Which is explained in Class I. 2. 3. 14. and in Sect. XXIX. 5. 2. These patients generally die suddenly; and on examining the thorax no certain cause, or seat, of the disease has been detected; some have supposed the valves of the arteries, or of the heart, were imperfect; and others that the accumulation of fat about this viscus or the lungs obstructed their due action; but other observations do not accord with these suppositions. Mr. W----, an elderly gentleman, was seized with asthma during the hot part of last summer; he always waked from his first sleep with difficult respiration, and pain in the middle of his sternum, and after about an hour was enabled to sleep again. As this had returned for about a fortnight, it appeared to me to be an asthma complicated with the disease, which Dr. Heberden has called angina pectoris. It was treated by venesection, a cathartic, and then by a grain of opium given at going to bed, with ether and tincture of opium when the pain or asthma required, and lastly with the bark, but was several days before it was perfectly subdued. This led me to conceive, that in this painful asthma the diaphragm, as well as the other muscles of respiration, was thrown into convulsive action, and that the fibres of this muscle not having proper antagonists, a painful fixed spasm of it, like that of the muscles in the calf of the leg in the cramp, might be the cause of death in the angina pectoris, which I have thence arranged under the name of painful asthma, and leave for further investigation. From the history of the case of the late much lamented John Hunter, and from the appearances after death, the case seems to have been of this kind, complicated with vertigo and consequent affection of the stomach. The remote cause seems to have arisen from ossifications of the coronary arteries; and the immediate cause of his death from fixed spasm of the heart. Other histories and dissections are still required to put this matter out of doubt; as it is possible, that either a fixed spasm of the diaphragm, or of the heart, which are both furnished with but weak antagonists, may occasion sudden death; and these may constitute two distinct diseases. Four patients I have now in my recollection, all of whom I believed to labour under the angina pectoris in a great degree; which have all recovered, and have continued well three or four years by the use, as I believe, of issues on the inside of each thigh; which were at first large enough to contain two pease each, and afterwards but one. They took besides some slight antimonial medicine for a while, and were reduced to half the quantity or strength of their usual potation of fermented liquor. The use of femoral issues in angina pectoris was first recommended by Dr. Macbride, physician at Dublin, Med. Observ. & Enquir. Vol. VI. And I was further induced to make trial of them, not only because the means which I had before used were inadequate, but from the ill effect I once observed upon the lungs, which succeeded the cure of a small sore beneath the knee; and argued conversely, that issues in the lower limbs might assist a difficult respiration. Mrs. L----, about fifty, had a small sore place about the size of half a pea on the inside of the leg a little below the knee. It had discharged a pellucid fluid, which she called a ley-water, daily for fourteen years, with a great deal of pain; on which account she applied to a surgeon, who, by means of bandage and a saturnine application, soon healed the sore, unheedful of the consequences. In less than two months after this I saw her with great difficulty of breathing, which with universal anasarca soon destroyed her. The theory of the double effect of issues, as above related, one in relieving by their presence the asthma dolorificum, and the other in producing by its cure an anasarca of the lungs, is not easy to explain. Some similar effects from cutaneous eruptions and from blisters are mentioned in Class I. 1. 2. 9. In these cases it seems probable, that the pain occasioned by issues, and perhaps the absorption of a small quantity of aerated purulent matter, stimulate the whole system into greater energy of action, and thus prevent the torpor which is the beginning of so many diseases. In confirmation of this effect of pain on the system, I remember the case of a lady of an ingenious and active mind, who, for many of the latter years of her life, was perpetually subject to great pains of her head from decaying teeth. When all her teeth were gone, she became quite low spirited, and melancholy in the popular sense of that word, and after a year or two became universally dropsical and died. M. M. Issues in the thighs. Five grains of rhubarb, and one sixth of a grain of emetic tartar every night for some months, with or without half a grain of opium. No stronger liquor than small beer, or wine diluted with twice its quantity of water. Since I wrote the above I have seen two cases of hydrops thoracis, attended with pain in the left arm, so as to be mistaken for asthma dolorificum, in which femoral issues, though applied early in the disease, had no effect. 12. _Stridor dentium._ The clattering of the teeth on going into cold water, or in the beginning of ague-fits, is an exertion along with the tremblings of the skin to relieve the pain of cold. The teeth and skin being more sensible to cold than the more internal parts, and more exposed to it, is the reason that the muscles, which serve them, are thrown into exertion from the pain of cold rather than those of respiration, as in screaming from more acute pain. Thus the poet, Put but your toes into cold water, Your correspondent teeth will clatter. PRIOR. In more acute pains the jaws are gnashed together with great vehemence, insomuch that sometimes the teeth are said to have been broken by the force. See Sect. XXXIV. 1. 3. In these cases something should be offered to the patient to bite, as a towel, otherwise they are liable to tear their own arms, or to bite their attendants, as I have witnessed in the painful epilepsy. 13. _Tetanus trismus._ Cramp. The tetanus consists of a fixed spasm of almost all the muscles of the body; but the trismus, or locked jaw, is the most frequent disease of this kind. It is generally believed to arise from sympathy with an injured tendon. In one case where it occurred in consequence of a broken ankle from a fall from a horse, it was preceded by evident hydrophobia. Amputation was advised, but not submitted to; two wounds were laid into one with scissors, but the patient died about the seventh day from the accident. In this case the wounded tendon, like the wounds from the bite of a mad dog, did not produce the hydrophobia, and then the locked jaw, till several days after the accident. I twice witnessed the locked jaw from a pain beneath the sternum, about the part where it is complained of in painful asthma, or angina pectoris, in the same lady at some years distance of time. The last time it had continued two days, and she wrote her mind, or expressed herself by signs. On observing a broken tooth, which made a small aperture into her mouth, I rolled up five grains of opium like a worm about an inch long, and introducing it over the broken tooth, pushed it onward by means of a small crow-quill; as it dissolved I observed she swallowed her saliva, and in less than half an hour, she opened her mouth and conversed as usual. Men are taught to be ashamed of screaming from pain in their early years; hence they are prone to exert the muscles of the jaws instead, which they have learnt to exert frequently and violently from their infancy; whence the locked jaw. This and the following spasm have no alternate relaxations, like the preceding ones; which is perhaps owing, first, to the weakness of their antagonist muscles, those which elevate the jaw being very strong for the purpose of biting and masticating hard substances, and for supporting the under jaw, with very weak antagonist muscles; and secondly, to their not giving sufficient relief even for a moment to the pain, or its preceding irritation, which excited them. M. M. Opium in very large quantities. Mercurial ointment used extensively. Electricity. Cold bath. Dilate the wound, and fill it with lint moistened with spirit of turpentine; which inflames the wound, and cures or prevents the convulsions. See a case, Transact. of American Society, Vol. II. p. 227. Wine in large quantities in one case was more successful than opium; it probably inflames more, which in this disease is desirable. Between two or three ounces of bark, and from a quart to three pints of wine a day, succeeded better than opium. Ib. 14. _Tetanus dolorificus._ Painful cramp. This kind of spasm most frequently attacks the calf of the leg, or muscles of the toes; it often precedes paroxysms of gout, and appears towards the end of violent diarrhoea, and from indigestion, or from acid diet. In these cases it seems to sympathize with the bowels, but is also frequently produced by the pain of external cold, and to the too great previous extension of the muscles, whence some people get the cramp in the extensor muscles of the toes after walking down hill, and of those of the calf of the leg after walking up a steep eminence. For the reason why these cramps commence in sleep, see Sect. XVIII. 15. The muscle in this disease contracts itself to relieve some smaller pain, either from irritation or association, and then falls into great pain itself, from the too great action of its own fibres. Hence any muscle, by being too vehemently exerted, falls into cramp, as in swimming too forcibly in water, which is painfully cold; and a secondary pain is then induced by the too violent contraction of the muscle; though the pain, which was the cause of the contraction, ceases. Which accounts for the continuance of the contraction, and distinguishes this disease from other convulsions, which are relaxed and exerted alternately. Hence whatever may be the cause of the primary pain, which occasions the cramp of the calf of the leg, the secondary one is relievable by standing up, and thus by the weight of the body on the toes forcibly extending the contracted muscles. For the cause, which induces these muscles of the calf of the leg to fall into more violent contraction than other spasmodic muscles, proceeds from the weakness of their antagonist muscles; as they are generally extended again after action by the weight of the body on the balls of the toes. See the preceding article. M. M. Rub the legs with camphor dissolved in oil, and let the patient wear stockings in bed. If a foot-board be put at the bed's feet, and the bed be so inclined, that he will rest a little with his toes against the foot-board, that pressure is said to prevent the undue contractions of the musculi gastrocnemii, which constitute the calf of the leg. In gouty patients, or where the bowels are affected with acidity, half a grain of opium, and six grains of rhubarb, and six of chalk, every night. Flesh-meat to supper. A little very weak warm spirit and water may be taken for present relief, when these cramps are very troublesome to weak or gouty patients. 15. _Hydrophobia._ Dread of water generally attending canine madness. I was witness to a case, where this disease preceded the locked jaw from a wound in the ankle, occasioned by a fall from a horse; as mentioned in the preceding article. It came on about the sixth day after the accident; when the patient attempted to swallow fluids, he became convulsed all over from the pain of this attempt, and spurted them out of his mouth with violence. It is also said to happen in some hysterical cases. Hence it seems rather the immediate consequence of a pained tendon, than of a contagious poison. And is so far analogous to tetanus, according with the opinions of Doctor Rusch and Doctor Percival. In other respects, as it is produced by the saliva of an enraged animal instilled into a wound, it would seem analogous to the poison of venomous animals. And from the manner of its access so long after the bite, and of its termination in a short time, it would seem to resemble the progress of contagious fevers. See Sect. XXII. 3. 3. If the patient was bitten in a part, which could be totally cut away, as a finger, even after the hydrophobia appears, it is probable it might cure it; as I suspect the cause still remains in the wounded tendon, and not in a diffused infection tainting the blood. Hence there are generally uneasy sensations, as cold or numbness, in the old cicatrix, before the hydrophobia commences. See a case in Medical Communications, Vol. II. p. 190. If the diseased tendon could be inflamed without cutting it out, as by cupping, or caustic, or blister after cupping, and this in the old wound long since healed, after the hydrophobia commences, might prevent the spasms about the throat. As inflaming the teeth by the use of mercury is of use in some kinds of hemicrania. Put spirit of turpentine on the wound, wash it well. See Class I. 3. 1. 11. IV. 1. 2. 7. M. M. Wine, musk, oil, internally. Opium, mercurial ointment, used extensively. Mercurial fumigation. Turpeth mineral. To salivate the patient as soon as possible. Exsection or a caustic on the scar, even after the appearance of hydrophobia. Put a tight bandage on the limb above the scar of the old wound to benumb the pained tendon, however long the wound may have been healed. Could a hollow catheter of elastic gum, caoutchouc, be introduced into the oesophagus by the mouth or nostril, and liquid nourishment be thus conveyed into the stomach? See Desault's Journal, Case I. where, in an ulcer of the mouth, such a catheter was introduced by the nostril, and kept in the oesophagus for a month, by which means the patient was nourished and preserved. It is recommended by Dr. Bardsley to give oil internally by a similar method contrived by Mr. John Hunter. He covered a probang with the skin of a small eel, or the gut of a lamb or cat. It was tied up at one end above and below the sponge, and a slit made above the upper ligature; to the other end of the eel-skin or gut was fixed a bladder and pipe. The probang thus covered was introduced into the stomach, and the liquid food or medicine was put into the bladder and squeezed down through the eel-skin. Mem. of Society at Manchester. See Class I. 2. 3. 25. Dr. Bardsley has endeavoured to prove, that dogs never experience the hydrophobia, or canine madness, without having been previously bitten or infected; and secondly, that the disease in this species of animal always shews itself in five or six weeks; and concludes from hence, that this dreadful malady might be annihilated by making all the dogs in Great Britain perform a kind of quarantine, by shutting them up for a certain number of weeks. Though the disease from the bite of the mad dog is perhaps more analogous to those from the wounds inflicted by venomous animals than to those from other contagious matter, yet these observations are well worthy further attention; which the author promises. * * * * * ORDO I. _Increased Volition._ GENUS II. _With increased Actions of the Organs of Sense._ In every species of madness there is a peculiar idea either of desire or aversion, which is perpetually excited in the mind with all its connections. In some constitutions this is connected with pleasurable ideas without the exertion of much muscular action, in others it produces violent muscular action to gain or avoid the object of it, in others it is attended with despair and inaction. Mania is the general word for the two former of these, and melancholia for the latter; but the species of them are as numerous as the desires and aversions of mankind. In the present age the pleasurable insanities are most frequently induced by superstitious hopes of heaven, by sentimental love, and by personal vanity. The furious insanities by pride, anger, revenge, suspicion. And the melancholy ones by fear of poverty, fear of death, and fear of hell; with innumerable others. Quicquid agunt homines, votum, timor, ira, voluptas, Gaudia, discursus, nostri est farrago libelli. JUVEN. I. 85. This idea, however, which induces madness or melancholy, is generally untrue; that is, the object is a mistaken fact. As when a patient is persuaded he has the itch, or venereal disease, of which he has no symptom, and becomes mad from the pain this idea occasions. So that the object of madness is generally a delirious idea, and thence cannot be conquered by reason; because it continues to be excited by painful sensation, which is a stronger stimulus than volition. Most frequently pain of body is the cause of convulsion, which is often however exchanged for madness; and a painful delirious idea is most frequently the cause of madness originally, but sometimes of convulsion. Thus I have seen a young lady become convulsed from a fright, and die in a few days; and a temporary madness frequently terminates the paroxysms of the epilepsia dolorifica, and an insanity of greater permanence is frequently induced by the pains or bruises of parturition. Where the patient is debilitated a quick pulse sometimes attends insane people, which is nevertheless generally only a symptom of the debility, owing to the too great expenditure of sensorial power; or of the paucity of its production, as in inirritative, or in sensitive inirritated fever. See III. 1. 1. But nevertheless where the quick pulse is permanent, it shews the presence of fever; and as the madness then generally arises from the disagreeable sensations attending the fever, it is so far a good symptom; because when the fever is cured, or ceases spontaneously, the insanity most frequently vanishes at the same time. The stimulus of so much volition supports insane people under variety of hardships, and contributes to the cure of diseases from debility, as sometimes occurs towards the end of fevers. See Sect. XXXIV. 2. 5. And, on the same account, they bear large doses of medicines to procure any operation on them; as emetics, and cathartics, which, before they produce their effect in inverting the motions of the stomach in vomiting, or of the absorbents of the bowels in purging, must first weaken the natural actions of those organs, as shewn in Sect. XXXV. 1. 3. From these considerations it appears, that the indications of cure must consist in removing the cause of the pain, whether it arises from a delirious idea, or from a real fact, or from bodily disease; or secondly, if this cannot be done, by relieving the pain in consequence of such idea or disease. The first is sometimes effected by presenting frequently in a day contrary ideas to shew the fallacy, or the too great estimation, of the painful ideas. 2dly. By change of place, and thus presenting the stimulus of new objects, as a long journey. 3dly. By producing forgetfulness of the idea or object, which causes their pain; by removing all things which recal it to their minds; and avoiding all conversation on similar subjects. For I suppose no disease of the mind is so perfectly cured by other means as by forgetfulness. Secondly, the pain in consequence of the ideas or bodily diseases above described is to be removed, first, by evacuations, as venesection, emetics, and cathartics; and then by large doses of opium, or by the vertigo occasioned by a circulating swing, or by a sea-voyage, which, as they affect the organs of sense as well as evacuate the stomach, may contribute to answer both indications of cure. Where maniacs are outrageous, there can be no doubt but coercion is necessary; which may be done by means of a straight waistcoat; which disarms them without hurting them; and by tying a handkerchief round their ankles to prevent their escape. In others there can be no doubt, but that confinement retards rather than promotes their cure; which is forwarded by change of ideas in consequence of change of place and of objects, as by travelling or sailing. The circumstances which render confinement necessary, are first, if the lunatic is liable to injure others, which must be judged of by the outrage he has already committed. 2dly. If he is likely to injure himself; this also must be judged of by the despondency of his mind, if such exists. 3dly. If he cannot take care of his affairs. Where none of these circumstances exist, there should be no confinement. For though the mistaken idea continues to exist, yet if no actions are produced in consequence of it, the patient cannot be called insane, he can only be termed delirious. If every one, who possesses mistaken ideas, or who puts false estimates on things, was liable to confinement, I know not who of my readers might not tremble at the sight of a madhouse! The most convenient distribution of insanities will be into general, as mania mutabilis, studium inane, and vigilia; and into partial insanities. These last again may be subdivided into desires and aversions, many of which are succeeded by pleasurable or painful ideas, by fury or dejection, according to the degree or violence of their exertions. Hence the analogy between the insanities of the mind, and the convulsions of the muscles described in the preceding genus, is curiously exact. The convulsions without stupor, are either just sufficient to obliterate the pain, which occasions them; or are succeeded by greater pain, as in the convulsio dolorifica. So the exertions in the mania mutabilis are either just sufficient to allay the pain which occasions them, and the patient dwells comparatively in a quiet state; or those exertions excite painful ideas, which are succeeded by furious discourses, or outrageous actions. The studium inane, or reverie, resembles epilepsy, in which there is no sensibility to the stimuli of external objects. Vigilia, or watchfulness, may be compared to the general writhing of the body; which is just a sufficient exertion to relieve the pain which occasions it. Erotomania may be compared to trismus, or other muscular fixed spasm, without much subsequent pain; and mæror to cramp of the muscles of the leg, or other fixed spasm with subsequent pain. All these coincidences contribute to shew, as explained in Sect. III. 5, that our ideas are motions of the immediate organs of sense obeying the same laws as our muscular motions. The violence of action accompanying insanity depends much on the education of the person; those who have been proudly educated with unrestrained passions, are liable to greater fury; and those, whose education has been humble, to greater despondency. Where the delirious idea, above described, produces pleasurable sensations, as in personal vanity or religious enthusiasm; it is almost a pity to snatch them from their fool's paradise, and reduce them again to the common lot of humanity; lest they should complain of their cure, like the patient described in Horace, --------Pol! me occidistis, amici, Non servastis, ait, cui sic extorta voluptas, Et demptus per vim mentis gratissimus error! The disposition to insanity, as well as to convulsion, is believed to be hereditary; and in consequence to be induced in those families from slighter causes than in others. Convulsions have been shewn to have been most frequently induced by pains owing to defect of stimulus, as the shuddering from cold, and not from pains from excess of stimulus, which are generally succeeded by inflammation. But insanities are on the contrary generally induced by pains from excess of stimulus, as from the too violent actions of our ideas, as in common anger, which is an insanity of short duration; for insanities generally, though not always, arise from pains of the organs of sense; but convulsions generally, though not always, from pains of the membranes or glands. And it has been previously explained, that though the membrane and glands, as the stomach and skin, receive great pain from want of stimulus; yet that the organs of sense, as the eye and ear, receive no pain from defect of stimulus. Hence it follows, that the constitutions most liable to convulsion, are those which most readily become torpid in some part of the system, that is, which possess less irritability; and that those most liable to insanity, are such as have excess of sensibility; and lastly, that these two circumstances generally exist in the same constitution; as explained in Sect. XXXI. 2. on Temperaments. These observations explain why epilepsy and insanity frequently succeed or reciprocate with each other, and why inirritable habits, as scrophulous ones, are liable to insanity, of which I have known some instances. In many cases however there is no appearance of the disposition to epilepsy or insanity of the parent being transmitted to the progeny. First, where the insanity has arisen from some violent disappointment, and not from intemperance in the use of spirituous liquors. Secondly, where the parent has acquired the insanity or epilepsy by habits of intoxication after the procreation of his children. Which habits I suppose to be the general cause of the disposition to insanity in this country. See Class III. 1. 1. 7. As the disposition to gout, dropsy, epilepsy, and insanity, appears to be produced by the intemperate use of spirituous potation, and is in all of them hereditary; it seems probable, that this disposition gradually increases from generation to generation, in those families which continue for many generations to be intemperate in this respect; till at length these diseases are produced; that is, the irritability of the system gradually is decreased by this powerful stimulus, and the sensibility at the same time increased, as explained in Sect. XXXI. 1. and 2. This disposition is communicated to the progeny, and becomes still increased, if the same stimulus be continued, and so on by a third and fourth generation; which accounts for the appearance of epilepsy in the children of some families, where it was never known before to have existed, and could not be ascribed to their own intemperance. A parity of reasoning shews, that a few sober generations may gradually in the same manner restore a due degree of irritability to the family, and decrease the excess of sensibility. From hence it would appear probable, that scrophula and dropsy are diseases from inirritability; but that in epilepsy and insanity an excess of sensibility is added, and the two faulty temperaments are thus conjoined. SPECIES. 1. _Mania mutabilis._ Mutable madness. Where the patients are liable to mistake ideas of sensation for those from irritation, that is, imaginations for realities, if cured of one source of insanity, they are liable in a few months to find another source in some new mistaken or imaginary idea, and to act from this new idea. The idea belongs to delirium, when it is an imaginary or mistaken one; but it is the voluntary actions exerted in consequence of this mistaken idea, which constitute insanity. In this disease the patient is liable carefully to conceal the object of his desire or aversion. But a constant inordinate suspicion of all people, and a carelessness of cleanliness, and of decency, are generally concomitants of madness. Their designs cannot be counteracted, till you can investigate the delirious idea or object of their insanity; but as they are generally timid, they are therefore less to be dreaded. Z. Z. called a young girl, one of his maid-servants, into the parlour, and, with cocked pistols in his hands, ordered her to strip herself naked; he then inspected her with some attention, and dismissed her untouched. Then he stripped two of his male servants in the same manner, to the great terror of the neighbourhood. After he was secured, with much difficulty he was persuaded to tell me, that he had got the itch, and had examined some of his servants to find out from whom he had received it; though at the same time there was not a spot to be seen on his hands, or other parts. The outrages in consequence of this false idea were in some measure to be ascribed to the pride occasioned by unrestrained education, affluent wealth, and dignified family. Madness is sometimes produced by bodily pain, particularly I believe of a diseased liver, like convulsion and epilepsy; at other times it is caused by very painful ideas occasioned by external circumstances, as of grief or disappointment; but the most frequent cause of insanity arises from the pain of some imaginary or mistaken idea; which may be termed hallucinatio maniacalis. This hallucination of one of the senses is often produced in an instant, and generally becomes gradually weakened in process of time, by the perpetual stimulus of external objects, or by the successions of other catenations of ideas, or by the operations of medicines; and when the maniacal hallucination ceases, or is forgotten, the violent exertions cease, which were in consequence of it, and the disease is cured. Mr. ----, a clergyman, about forty years of age, who was rather a weak man, happened to be drinking wine in jocular company, and by accident swallowed a part of the seal of a letter, which he had just then received; one of his companions seeing him alarmed, cried out in humour, "It will seal your bowels up." He became melancholy from that instant, and in a day or two refused to swallow any kind of nourishment. On being pressed to give a reason for this refusal, he answered, he knew nothing would pass through him. A cathartic was given, which produced a great many evacuations, but he still persisted, that nothing passed through him; and though he was frightened into taking a little broth once or twice by threats, yet he soon ceased intirely to swallow any thing, and died in consequence of this insane idea. Miss ----, a sensible and ingenious lady, about thirty, said she had seen an angel; who told her, that she need not eat, though all others were under the necessity of supporting their earthly existence by food. After fruitless persuasions to take food, she starved herself to death.--It was proposed to send an angel of an higher order to tell her, that now she must begin to eat and drink again; but it was not put into execution. Mrs. ----, a lady between forty and fifty years of age, imagined that she heard a voice say to her one day, as she was at her toilet, "Repent, or you will be damned." From that moment she became melancholy, and this hallucination affected her in greater or less degree for about two years; she then recovered perfectly, and is now a cheerful old woman. Mrs. ----, a farmer's wife, going up stairs to dress, found the curtains of her bed drawn, and on undrawing them, she believed that she saw the corpse of her sister, who was then ill at the distance of twenty miles, and became from that time insane; and as her sister died about the time, she could not be produced to counteract the insane hallucination, but she perfectly recovered in a few months. Mrs. ----, a most elegant, beautiful, and accomplished lady, about twenty-two years of age, had been married about two months to an elegant, polished, and affluent young man, and it was well known to be a love-match on both sides. She suddenly became melancholy, and yet not to so great a degree, but that she could command herself to do the honours of her table with grace and apparent ease. After many days intreaty, she at length told me, that she thought her marrying her husband had made him unhappy; and that this idea she could not efface from her mind day or night. I withstood her being confined, as some had advised, and proposed a sea-voyage to her, with expectation that the sickness, as well as change of objects, might remove the insane hallucination, by introducing other energetic ideas; this was not complied with, but she travelled about England with her friends and her husband for many months, and at length perfectly recovered, and is now I am informed in health and spirits. These cases are related to shew the utility of endeavouring to investigate the maniacal idea, or hallucination; as it may not only acquaint us with the probable designs of the patient, from whence may be deduced the necessity of confinement; but also may some time lead to the most effectual plan of cure. I received good information of the truth of the following case, which was published a few years ago in the newspapers. A young farmer in Warwickshire, finding his hedges broke, and the sticks carried away during a frosty season, determined to watch for the thief. He lay many cold hours under a hay-stack, and at length an old woman, like a witch in a play, approached, and began to pull up the hedge; he waited till she had tied up her bottle of sticks, and was carrying them off, that he might convict her of the theft, and then springing from his concealment, he seized his prey with violent threats. After some altercation, in which her load was left upon the ground, she kneeled upon her bottle of sticks, and raising her arms to heaven beneath the bright moon then at the full, spoke to the farmer already shivering with cold, "Heaven grant, that thou never mayest know again the blessing to be warm." He complained of cold all the next day, and wore an upper coat, and in a few days another, and in a fortnight took to his bed, always saying nothing made him warm, he covered himself with very many blankets, and had a sieve over his face, as he lay; and from this one insane idea he kept his bed above twenty years for fear of the cold air, till at length he died. M. M. As mania arises from pain either of our muscles or organs of sense, the arts of relieving pain must constitute the method of cure. See Sect. XXXIV. 3. 4. Venesection. Vomits of from five grains to ten of emetic tartar, repeated every third morning for three or four times; with solution of gum-ammoniac, and soluble tartar, so as to purge gently every day. Afterwards warm bath for two or three hours a day. Opium in large doses. Bark. Steel. Dr. Binns gave two scruples (40 grains) of solid opium at a dose, and twenty grains four hours afterwards; which restored the patient. Dr. Brandreth gave 400 drops of laudanum to a maniac in the greatest possible furor, and in a few hours he became calm and rational. Med. Comment for 1791, p. 384. _Prognostic._ The temporary quick pulse attending some maniacal cases is simply a symptom of debility, and is the consequence of too great exertions; but a permanent quick pulse shews the presence of fever, and is frequently a salutary sign; because, if the life of the patient be safe, when the fever ceases, the insanity generally vanishes along with it, as mentioned above. In this case the kind of fever must direct the method of curing the insanity; which must consist of moderate evacuations and diluents, if the pulse be strong; or by nutrientia, bark, and small doses of opium, if the pulse be weak. Where the cause is of a temporary nature, as in puerperal insanity, there is reason to hope, that the disease will cease, when the bruises, or other painful sensations attending this state, are removed. In these cases the child should be brought frequently to the mother, and applied to her breast, if she will suffer it, and this whether she at first attends to it or not; as by a few trials it frequently excites the storgè, or maternal affection, and removes the insanity, as I have witnessed. When the madness is occasioned by pain of the teeth, which I believe is no uncommon case, these must be extracted; and the cure follows the extinction of the pain. There is however some difficulty in detecting the delinquent tooth in this case, as in hemicrania, unless by its apparent decay, or by some previous information of its pain having been complained of; because the pain of the tooth ceases, as soon as the exertions of insanity commence. When a person becomes insane, who has a family of small children to solicit his attention, the prognostic is very unfavourable; as it shews the maniacal hallucination to be more powerful than those ideas which generally interest us the most. 2. _Studium inane._ Reverie consists of violent voluntary exertions of ideas to relieve pain, with all the trains or tribes connected with them by sensations or associations. It frequently alternates with epileptic convulsions; with which it corresponds, in respect to the insensibility of the mind to the stimuli of external objects, in the same manner as madness corresponds with common convulsion, in the patient's possessing at the same time a sensibility of the stimuli of external objects. Some have been reported to have been involved in reverie so perfectly, as not to have been disturbed by the discharge of a cannon; and others to have been insensible to torture, as the martyrs for religious opinions; but these seem more properly to belong to particular insanities than to reverie, like nostalgia and erotomania. Reverie is distinguished from madness as described above; and from delirium, because the trains of ideas are kept consistent by the power of volition, as the person reasons and deliberates in it. Somnambulismus is a part of reverie, the latter consisting in the exertions of the locomotive muscles, and the former of the exertions of the organs of sense; see Class III. 1. 1. 9. and Sect. XIX. both which are mixed, or alternate with each other, for the purpose of relieving pain. When the patients in reverie exert their volition on their organs of sense, they can occasionally perceive the stimuli of external objects, as explained in Sect. XIX. And in this case it resembles sometimes an hallucination of the senses, as there is a mixture of fact and imagination in their discourse; but may be thus distinguished: hallucinations of the lenses are allied to delirium, and are attended generally with quick pulse, and other symptoms of great debility; but reverie is without fever, and generally alternates with convulsions; and so much intuitive analogy (see Sect. XVII. 3. 7.) is retained in its paroxysms, as to preserve a consistency in the trains of ideas. Miss G----, whose case is related in Sect. III. 5. 8. said, as I once sat by her, "My head is fallen off, see it is rolled to that corner of the room, and the little black dog is nibbling the nose off." On my walking to the place which she looked at, and returning, and assuring her that her nose was unhurt, she became pacified, though I was doubtful whether she attended to me. See Class III. 1. 1. 9. and Class III. 1. 2. 2. M. M. Large doses of opium given before the expected paroxysm, as in epilepsia dolorifica, Class III. 1. 1. 8. The hallucinatio studiosa, or false ideas in reverie, differ from maniacal hallucinations above described, as no insane exertions succeed, and in the patients whom I have seen they have always been totally forgotten, when the paroxysm was over. Master ----, a school-boy about twelve years old, after he came out of a convulsion fit and sat up in bed, said to me, "Don't you see my father standing at the feet of the bed, he is come a long way on foot to see me." I answered, no: "What colour is his coat!" He replied, "A drab colour." "And what buttons?" "Metal ones," he answered, and added, "how sadly his legs are swelled." In a few minutes he said, with apparent surprise, "He is gone," and returned to his perfect mind. Other cases are related in Sect. XIX. and XXXIV. 3. and in Class III. 1. 2. 2. with further observations on this kind of hallucination; which however is not the cause of reverie, but constitutes a part of it, the cause being generally some uneasy sensation of the body. 3. _Vigilia._ Watchfulness consists in the unceasing exertion of volition; which is generally caused by some degree of pain either of mind or of body, or from defect of the usual quantity of pleasurable sensation; hence if those, who are accustomed to wine at night, take tea instead, they cannot sleep. The same happens from want of solid food for supper, to those who are accustomed to use it; as in these cases there is pain or defect of pleasure in the stomach. Sometimes the anxiety about sleeping, that is the desire to sleep, prevents sleep; which consists in an abolition of desire or will. This may so far be compared to the impediment of speech described in Sect. XVII. 1. 10. as the interference of the will prevents the effect desired. Another source of watchfulness may be from the too great secretion of sensorial power in the brain, as in phrenzy, and as sometimes happens from the exhibition of opium, and of wine; if the exhaustion of sensorial power by the general actions of the system occasioned by the stimulus of these drugs can be supposed to be less than the increased secretion of it. M. M. 1. Solid food to supper. Wine. Opium. Warm bath. 2. The patient should be told that his want of sleep is of no consequence to his health. 3. Venesection by cupping. Abstinence from wine. 4. A blister by stimulating the skin, and rhubarb by stimulating the bowels, will sometimes induce sleep. Exercise. An uniform sound, as of a pausing drop of water, or the murmur of bees. Other means are described in Sect. XVIII. 20. 4. _Erotomania._ Sentimental love. Described in its excess by romance-writers and poets. As the object of love is beauty, and as our perception of beauty consists in a recognition by the sense of vision of those objects, which have before inspired our love, by the pleasure they have afforded to many of our senses (Sect. XVI. 6); and as brute animals have less accuracy of their sense of vision than mankind (ib.); we see the reason why this kind of love is not frequently observable in the brute creation, except perhaps in some married birds, or in the affection of the mother to her offspring. Men, who have not had leisure to cultivate their taste for visible objects, and who have not read the works of poets and romance-writers, are less liable to sentimental love; and as ladies are educated rather with an idea of being chosen, than of choosing; there are many men, and more women, who have not much of this insanity; and are therefore more easily induced to marry for convenience or interest, or from the flattery of one sex to the other. In its fortunate gratification sentimental love is supposed to supply the purest source of human felicity; and from the suddenness with which many of those patients, described in Species I. of this genus, were seized with the maniacal hallucination, there is reason to believe, that the most violent sentimental love may be acquired in a moment of time, as represented by Shakespeare in the beginning of his Romeo and Juliet. Some have endeavoured to make a distinction between beauty and grace, and have made them as it were rivals for the possession of the human heart; but grace may be defined beauty in action; for a sleeping beauty cannot be called graceful in whatever attitude she may recline; the muscles must be in action to produce a graceful attitude, and the limbs to produce a graceful motion. But though the object of love is beauty, yet the idea is nevertheless much enhanced by the imagination of the lover; which appears from this curious circumstance, that the lady of his passion seldom appears so beautiful to the lover after a few months separation, as his ideas had painted her in his absence; and there is, on that account, always a little disappointment felt for a minute at their next interview from this hallucination of his ideas. This passion of love produces reverie in its first state, which exertion alleviates the pain of it, and by the assistance of hope converts it into pleasure. Then the lover seeks solitude, lest this agreeable reverie should be interrupted by external stimuli, as described by Virgil. Tantum inter densas, umbrosa cacumina, fagos Assiduè veniebat, ibi hæc incondita solus Montibus et sylvis studio jactabat inani. When the pain of love is so great, as not to be relieved by the exertions of reverie, as above described; as when it is misplaced on an object, of which the lover cannot possess himself; it may still be counteracted or conquered by the stoic philosophy, which strips all things of their ornaments, and inculcates "nil admirari." Of which lessons may be found in the meditations of Marcus Antoninus. The maniacal idea is said in some lovers to have been weakened by the action of other very energetic ideas; such as have been occasioned by the death of his favourite child, or by the burning of his house, or by his being shipwrecked. In those cases the violence of the new idea for a while expends so much sensorial power as to prevent the exertion of the maniacal one; and new catenations succeed. On this theory the lover's leap, so celebrated by poets, might effect a cure, if the patient escaped with life. The third stage of this disease I suppose is irremediable; when a lover has previously been much encouraged, and at length meets with neglect or disdain; the maniacal idea is so painful as not to be for a moment relievable by the exertions of reverie, but is instantly followed by furious or melancholy insanity; and suicide, or revenge, have frequently been the consequence. As was lately exemplified in Mr. Hackman, who shot Miss Ray in the lobby of the playhouse. So the poet describes the passion of Dido, ----------Moriamur inultæ?-- At moriamur, ait,--sic, sic, juvat ire sub umbras! The story of Medæa seems to have been contrived by Ovid, who was a good judge of the subject, to represent the savage madness occasioned by ill-requited love. Thus the poet, Earth has no rage like love to hatred turn'd, Nor hell a fury like a woman scorn'd. DRYDEN. 5. _Amor sui._ Vanity consists of an agreeable reverie, and is well ridiculed in the story of Narcissus, who so long contemplated his own beautiful image in the water, that he died from neglect of taking sustenance. I once saw a handsome young man, who had been so much flattered by his parents, that his vanity rose so near to insanity, that one might discern by his perpetual attention to himself, and the difficulty with which he arranged his conversation, that the idea of himself intruded itself at every comma or pause of his discourse. In this degree vanity must afford great pleasure to the possessor; and when it exists within moderate bounds, may contribute much to the happiness of social life. My friend Mr. ---- once complained to me, that he was much troubled with bashfulness in company, and believed that it arose from his want of personal vanity; on this account he determined on a journey to Paris, when Paris was the center of politeness; he there learnt to dress, to dance, and to move his hands gracefully in conversation; and returned a most consummate coxcomb. But after a very few years he relapsed into rusticity of dress and manners. M. M. The cure of vanity may be attempted by excess of flattery, which will at length appear ridiculous, or by its familiarity will cease to be desired. I remember to have heard a story of a nobleman in the court of France, when France had a court, who was so disagreeably vain in conversation, that the king was pleased to direct his cure, which was thus performed. Two gentlemen were directed always to attend him, one was to stand behind his chair, and the other at a respectful distance before him; whenever his lordship began to speak, one of them always pronounced, "Lord Gallimaufre is going to say the best thing in the world." And, as soon as his lordship had done speaking, the other attendant pronounced, "Lord Gallimaufre has spoken the best thing in the world." Till in a few weeks this noble lord was so disgusted with praise that he ceased to be vain; and his majesty dismissed his keepers. 6. _Nostalgia._ Maladie de Pais. Calenture. An unconquerable desire of returning to one's native country, frequent in long voyages, in which the patients become so insane as to throw themselves into the sea, mistaking it for green fields or meadows. The Swiss are said to be particularly liable to this disease, and when taken into foreign service frequently to desert from this cause, and especially after hearing or singing a particular tune, which was used in their village dances, in their native country, on which account the playing or singing this tune was forbid by the punishment of death. Zwingerus. Dear is that shed, to which his soul conforms, And dear that hill, which lifts him to the storms. GOLDSMITH. 7. _Spes religiosa._ Superstitious hope. This maniacal hallucination in its milder state produces, like sentimental love, an agreeable reverie; but when joined with works of supererogation, it has occasioned many enormities. In India devotees consign themselves by vows to most painful and unceasing tortures, such as holding up their hands, till they cannot retract them; hanging up by hooks put into the thick skin over their shoulders, sitting upon sharp points, and other self torments. While in our part of the globe fasting and mortification, as flagellation, has been believed to please a merciful deity! The serenity, with which many have suffered cruel martyrdoms, is to be ascribed to this powerful reverie. Mr. ----, a clergyman, formerly of this neighbourhood, began to bruise and wound himself for the sake of religious mortification, and passed much time in prayer, and continued whole nights alone in the church. As he had a wife and family of small children, I believed the case to be incurable; as otherwise the affection and employment in his family connections would have opposed the beginning of this insanity. He was taken to a madhouse without effect, and after he returned home, continued to beat and bruise himself, and by this kind of mortification, and by sometimes long fasting, he at length became emaciated and died. I once told him in conversation, that "God was a merciful being, and could not delight in cruelty, but that I supposed he worshipped the devil." He was struck with this idea, and promised me not to beat himself for three days, and I believe kept his word for one day. If this idea had been frequently forced on his mind, it might probably have been of service. When these works of supererogation have been of a public nature, what cruelties, murders, massacres, has not this insanity introduced into the world!--A commander, who had been very active in leading and encouraging the bloody deeds of St. Bartholomew's day at Paris, on confessing his sins to a worthy ecclesiastic on his death-bed, was asked, "Have you nothing to say about St. Bartholomew?" "On that day," he replied, "God Almighty was obliged to me!"--The fear of hell is another insanity, which will be spoken of below. 8. _Superbia stemmatis._ Pride of family has frequently formed a maniacal hallucination, which in its mild state has consisted in agreeable reverie, but when it has been so painful as to demand homage from others, it has frequently induced insane exertions. This insanity seems to have existed in the flourishing state of Rome, as now all over Germany, and is attacked by Juvenal with great severity, a small part of which I shall here give as a method of cure. Sat. 8. Say, what avails the pedigree, that brings Thy boasted line from heroes or from kings; Though many a mighty lord, in parchment roll'd, Name after name, thy coxcomb hands unfold; Though wreathed patriots crowd thy marble halls, Or steel-clad warriors frown along the walls; While on broad canvas in the gilded frame All virtues flourish, and all glories flame?-- Say,--if ere noon with idiot laugh you lie Wallowing in wine, or cog the dubious die, Or act unshamed, by each indignant bust, The midnight orgies of promiscuous lust!-- Go, lead mankind to Virtue's holy shrine, With morals mend them, and with arts refine, Or lift, with golden characters unfurl'd, The flag of peace, and still a warring world!-- --So shall with pious hands immortal Fame Wreathe all her laurels round thy honour'd name, High o'er thy tomb with chissel bold engrave, "THE TRULY NOBLE ARE THE GOOD AND BRAVE." 9. _Ambitio._ Inordinate desire of fame. A carelessness about the opinions of others is said by Xenophon to be the source of impudence; certainly a proper regard for what others think of us frequently incites us to virtuous actions, and deters us from vicious ones; and increases our happiness by enlarging our sphere of sympathy, and by flattering our vanity. Abstract what others feel, what others think, All pleasures sicken, and all glories sink. POPE. When this reverie of ambition excites to conquer nations, or to enslave them, it has been the source of innumerable wars, and the occasion of a great devastation of mankind. Cæsar is reported to have boasted, that he had destroyed three millions of his enemies, and one million of his friends. The works of Homer are supposed to have done great injury to mankind by inspiring the love of military glory. Alexander was said to sleep with them always on his pillow. How like a mad butcher amid a flock of sheep appears the hero of the Iliad, in the following fine lines of Mr. Pope, which conclude the twentieth book. His fiery coursers, as the chariot rolls, Tread down whole ranks, and crush out heroes' souls; Dash'd from their hoofs, as o'er the dead they fly, Black bloody drops the smoaking chariot dye;-- The spiky wheels through heaps of carnage tore, And thick the groaning axles dropp'd with gore; High o'er the scene of death ACHILLES stood, All grim with dust, all horrible with blood; Yet still insatiate, still with rage on flame, Such is the lust of never-dying fame! The cure must be taken from moral writers. Woolaston says, Cæsar conquered Pompey; that is, a man whose name consisted of the letters C. æ. s. a. r. conquered a long time ago a man, whose name consisted of the letters P. o. m. p. e. y. and that this is all that remains of either of them. Juvenal also attacks this mode of insanity, Sat. X. 166. --I, demens, et sævas curre per alpes, Ut pueris placeas, et declamatio fias! Which is thus translated by Dr. Johnson, And left a name, at which the world grew pale, To point a moral, or adorn a tale! 10. _Mæror._ Grief. A perpetual voluntary contemplation of all the circumstances of some great loss, as of a favourite child. In general the painful ideas gradually decrease in energy, and at length the recollection becomes more tender and less painful. The letter of Sulpicius to Cicero on the loss of his daughter is ingenious. The example of David on the loss of his child is heroic. A widow lady was left in narrow circumstances with a boy and a girl, two beautiful and lively children, the one six and the other seven years of age; as her circumstances allowed her to keep but one maid-servant, these two children were the sole attention, employment, and consolation of her life; she fed them, dressed them, slept with them, and taught them herself; they were both snatched from her by the gangrenous sore throat in one week: so that she lost at once all that employed her, as well as all that was dear to her. For the first three or four days after their death, when any friend visited her, she sat upright, with her eyes wide open, without shedding tears, and affected to speak of indifferent things. Afterwards she began to weep much, and for some weeks talked to her friends of nothing else but her dear children. But did not for many years, even to her dying hour, get quite over a gloom, which was left upon her countenance. In violent grief, when tears flow, it is esteemed a good symptom; because then the actions caused by sensitive association take the place of those caused by volition; that is, they prevent the voluntary exertions of ideas, or muscular actions, which constitute insanity. The sobbing and sighing attendant upon grief are not convulsive movements, they are occasioned by the sensorial power being so expended on the painful ideas, and their connections, that the person neglects to breathe for a time, and then a violent sigh or sob is necessary to carry on the blood, which oppresses the pulmonary vessels, which is then performed by deep or quick inspirations, and laborious expirations. Sometimes nevertheless the breath is probably for a while voluntarily held, as an effort to relieve pain. The paleness and ill health occasioned by long grief is spoken of in Class IV. 2. 1. 9. The melioration of grief by time, and its being at length even attended with pleasure, depends on our retaining a distinct idea of the lost object, and forgetting for a time the idea of the loss of it. This pleasure of grief is beautifully described by Akenside. Pleasures of Imagination, Book II. l. 680. ----------Ask the faithful youth, Why the cold urn of her, whom long he loved, So often fills his arms; so often draws His lonely footsteps at the silent hour To pay the mournful tribute of his tears? Oh! he will tell thee, that the wealth of worlds Should ne'er seduce his bosom to forego That sacred hour; when, stealing from the noise Of care and envy, sweet remembrance soothes With Virtue's kindest looks his aching breast, And turns his tears to rapture. M. M. Consolation is best supplied by the Christian doctrine of a happy immortality. In the pagan religion the power of dying was the great consolation in irremediable distress. Seneca says, "no one need be unhappy unless by his own fault." And the author of Telemachus begins his work by saying, that Calypso could not console herself for the loss of Ulysses, and found herself unhappy in being immortal. In the first hours of grief the methods of consolation used by uncle Toby, in Tristram Shandy, is probably the best; "he sat down in an arm chair by the bed of his distressed friend, and said nothing." 11. _Tædium vitæ._ The inanity of sublunary things has afforded a theme to philosophers, moralists, and divines, from the earliest records of antiquity; "Vanity of vanities!" says the preacher, "all is vanity!" Nor is there any one, I suppose, who has passed the meridian of life, who has not at some moments felt the nihility of all things. Weariness of life in its moderate degree has been esteemed a motive to action by some philosophers. See Sect. XXXIV. 2. 3. But in those men, who have run through the usual amusements of life early in respect to their age; and who have not industry or ability to cultivate those sciences, which afford a perpetual fund of novelty, and of consequent entertainment, are liable to become tired of life, as they suppose there is nothing new to be found in it, that can afford them pleasure; like Alexander, who is said to have shed tears, because he had not another world to conquer. Mr. ----, a gentleman about fifty, of polished manners, who in a few months afterwards destroyed himself, said to me one day, "a ride out in the morning, and a warm parlour and a pack of cards in the afternoon, is all that life affords." He was persuaded to have an issue on the top of his head, as he complained of a dull head-ach, which being unskilfully managed, destroyed the pericranium to the size of an inch in diameter; during the time this took in healing, he was indignant about it, and endured life, but soon afterwards shot himself. Mr. ----, a gentleman of Gray's Inn, some years ago was prevailed upon by his friends to dismiss a mistress, by whom he had a child, but who was so great a termagant and scold, that she was believed to use him very ill, and even to beat him. He became melancholy in two days from the want of his usual stimulus to action, and cut his throat on the third so completely, that he died immediately. Mr. Anson, the brother to the late Lord Anson, related to me the following anecdote of the death of Lord Sc----. His Lordship sent to see Mr. Anson on the Monday preceding his death, and said, "You are the only friend I value in the world, I determined therefore to acquaint you, that I am tired of the insipidity of life, and intend to-morrow to leave it." Mr. Anson said, after much conversation, that he was obliged to leave town till Friday, and added, "As you profess a friendship for me, do me this last favour, I entreat you, live till I return." Lord Sc---- believed this to be a pious artifice to gain time, but nevertheless agreed, if he should return by four o'clock on that day. Mr. Anson did not return till five, and found, by the countenances of the domestics, that the deed was done. He went into his chamber and found the corpse of his friend leaning over the arm of a great chair, with the pistol on the ground by him, the ball of which had been discharged into the roof of his mouth, and passed into his brain. Mr. ---- and Mr. ----, two young men, heirs to considerable fortunes, shot themselves at the age of four or five and twenty, without their friends being able to conjecture any cause for those rash actions. One of them I had long known to express himself with dissatisfaction of the world; at eighteen years of age he complained, that he could not entertain himself; he tried to study the law at Cambridge, and afterwards went abroad for a year or two by my advice; but returned dissatisfied with all things. As he had had an eruption for some years on a part of his face, which he probably endeavoured to remove by external applications; I was induced to ascribe his perpetual ennui to the pain or disagreeable sensation of a diseased liver. The other young gentleman shot himself in his bed-room, and I was informed that there was found written on a scrap of paper on his table, "I am impotent, and therefore not fit to live." From whence there was reason to conclude, that this was the hallucinatio maniacalis, the delirious idea, which caused him to destroy himself. The case therefore belongs to mania mutabilis, and not to tædium vitæ. M. M. Some restraint in exhausting the usual pleasures of the world early in life. The agreeable cares of a matrimonial life. The cultivation of science, as of chemistry, natural philosophy, natural history, which supplies an inexhaustible source of pleasurable novelty, and relieves ennui by the exertions it occasions. In many of these cases, whence irksomeness of life has been the ostensible cause of suicide, there has probably existed a maniacal hallucination, a painful idea, which the patient has concealed even to his dying hour; except where the mania has evidently arisen from hereditary or acquired disease of the membranous or glandular parts of the system. 12. _Pulchritudinis desiderium._ The loss of beauty, either by disease, as by the small-pox, or by age, as life advances, is sometimes painfully felt by ladies, who have been much flattered on account of it. There is a curious case of this kind related in Le Sage's Bachelor of Salamanca, which is too nicely described to be totally imaginary. In this situation some ladies apply to what are termed cosmetics under various names, which crowd the newspapers. Of these the white has destroyed the health of thousands; a calx, or magistery, of bismuth is supposed to be sold in the shops for this purpose; but it is either, I am informed, in part or entirely white lead or cerussa. The pernicious effects of the external use of those saturnine applications are spoken of in gutta rosea, Class II. 1. 4. 6. The real calx of bismuth would probably have the same ill effect. As the red paint is prepared from cochineal, which is an animal body, less if any injury arises from its use, as it only lies on the skin like other filth. The tan of the skin occasioned by the sun may be removed by lemon juice evaporated by the fire to half its original quantity, or by diluted marine acid; which cleans the cuticle, by eroding its surface, but requires much caution in the application; the marine acid must be diluted with water, and when put upon the hand or face, after a second of time, as soon as the tan disappears, the part must be washed with a wet towel and much warm water. Freckles lie too deep for this operation, nor are they in general removeable by a blister, as I once experienced. See Class I. 2. 2. 9. It is probable, that those materials which stain silk, or ivory, might be used to stain the cuticle, or hair, permanently; as they are all animal substances. But I do not know, that any trials of this kind have been made on the skin. I endeavoured in vain to whiten the back of my hand by marine acid oxygenated by manganese, which so instantly whitens cotton. The cure therefore must be sought from moral writers, and the cultivation of the graces of the mind, which are frequently a more valuable possession than celebrated beauty. 13. _Paupertatis timor._ The fear of poverty is one kind of avarice; it is liable to affect people who have left off a profitable and active business; as they are thus deprived of their usual exertions, and are liable to observe the daily expenditure of money, without calculating the source from whence it flows. It is also liable to occur with a sudden and unexpected increase of fortune. Mr. ----, a surgeon, about fifty years of age, who was always rather of a parsimonious disposition, had a large house, with a fortune of forty thousand pounds, left him by a distant relation; and in a few weeks became insane from the fear of poverty, lamenting that he should die in a jail or workhouse. He had left off a laborious country business, and the daily perception of profit in his books; he also now saw greater expences going forwards in his new house, than he had been accustomed to observe, and did not so distinctly see the source of supply; which seems to have occasioned the maniacal hallucination.--This idea of approaching poverty is a very frequent and very painful disease, so as to have induced many to become suicides, who were in good circumstances; more perhaps than any other maniacal hallucination, except the fear of hell. The covetousness of age is more liable to affect single men, than those who have families; though an accumulation of wealth would seem to be more desirable to the latter. But an old man in the former situation, has no personal connections to induce him to open his purse; and having lost the friends of his youth, and not easily acquiring new ones, feels himself alone in the world; feels himself unprotected, as his strength declines, and is thus led to depend for assistance on money, and on that account wishes to accumulate it. Whereas the father of a family has not only those connections, which demand the frequent expenditure of money, but feels a consolation in the friendship of his children, when age may render their good offices necessary to him. M. M. I have been well informed of a medical person in good circumstances in London, who always carries an account of his affairs, as debtor and creditor, in his pocket-book; and looks over it frequently in a day, when this disease returns upon him; and thus, by counteracting the maniacal hallucination, wisely prevents the increase of his insanity. Another medical person, in London, is said to have cured himself of this disease by studying mathematics with great attention; which exertions of the mind relieved the pain of the maniacal hallucination. Many moral writers have stigmatised this insanity; the covetous, they say, commit crimes and mortify themselves without hopes of reward; and thus become miserable both in this world and the next. Thus Juvenal: Cum furor haud dubius, cum sit manifesta phrenitis, Ut locuples moriaris, egenti vivere fato! The covetous man thought he gave good advice to the spendthrift, when he said, "Live like me," who well answered him, ----------"Like you, Sir John? "That I can do, when all I have is gone!" POPE. 14. _Lethi timor._ The fear of death perpetually employs the thoughts of these patients; hence they are devising new medicines, and applying to physicians and quacks without number. It is confounded with hypochondriasis, Class I. 2. 4. 10. in popular conversation, but is in reality an insanity. A young gentleman, whom I advised to go abroad as a cure for this disease, assured me, that during the three years he was in Italy and France he never passed a quarter of an hour without fearing he should die. But has now for above twenty years experienced the contrary. The sufferers under this malady are generally at once discoverable by their telling you, amidst an unconnected description of their complaints, that they are nevertheless not afraid of dying. They are also easily led to complain of pains in almost any part of the body, and are thus soon discovered. M. M. As the maniacal hallucination has generally arisen in early infancy from some dreadful account of the struggles and pain of dying, I have sometimes observed, that these patients have received great consolation from the instances I have related to them of people dying without pain. Some of these, which I think curious, I shall concisely relate, as a part of the method of cure. Mr. ----, an elderly gentleman, had sent for me one whole day before I could attend him; on my arrival he said he was glad to see me, but that he was now quite well, except that he was weak, but had had a pain in his bowels the day before. He then lay in bed with his legs cold up to the knees, his hands and arms cold, and his pulse scarcely discernible, and died in about six hours. Mr. ----, another gentleman about sixty, lay in the act of dying, with difficult respiration like groaning, but in a kind of stupor or coma vigil, and every ten or twelve minutes, while I sat by him, he waked, looked up, and said, "who is it groans so, I am sure there is somebody dying in the room," and then sunk again into a kind of sleep. From these two cases there appeared to be no pain in the act of dying, which may afford consolation to all, but particularly to those who are afflicted with the fear of death. 15. _Orci timor._ The fear of hell. Many theatric preachers among the Methodists successfully inspire this terror, and live comfortably upon the folly of their hearers. In this kind of madness the poor patients frequently commit suicide; although they believe they run headlong into the hell, which they dread! Such is the power of oratory, and such the debility of the human understanding! Those, who suffer under this insanity, are generally the most innocent and harmless people; who are then liable to accuse themselves of the greatest imaginary crimes, and have so much intellectual cowardice, that they dare not reason about those things, which they are directed by their priests to believe, however contradictory to human apprehension, or derogatory to the great Creator of all things. The maniacal hallucination at length becomes so painful, that the poor insane flies from life to become free from it. M. M. Where the intellectual cowardice is great, the voice of reason is ineffectual; but that of ridicule may save many from those mad-making doctors; though it is too weak to cure those, who are already hallucinated. Foot's Farces are recommended for this purpose. 16. _Satyriasis._ An ungovernable desire of venereal indulgence. The remote cause is probably the stimulus of the semen; whence the phallus becomes distended with blood by the arterial propulsion of it being more strongly excited than the correspondent venous absorption. At the same time a new sense is produced in the other termination of the urethra; which, like itching, requires some exterior friction to facilitate the removal of the cause of the maniacal actions, which may probably be increased in those cases by some associated hallucinations of ideas. It differs from priapismus chronicus in the desire of its appropriated object, which is not experienced in the latter, Class I. 1. 4. 6. and from the priapismus amatorius, Class II. 1. 7. 9. in the maniacal actions in consequence of desire. The furor uterius, or nymphomania, is a similar disease. M. M. Venesection. Cathartics. Torpentia. Marriage. 17. _Ira._ Anger is caused by the pain of offended pride. We are not angry at breaking a bone, but become quite insane from the smallest stroke of a whip from an inferior. Ira furor brevis. Anger is not only itself a temporary madness, but is a frequent attendant on other insanities, and as, whenever it appears, it distinguishes insanity from delirium, it is generally a good sign in fevers with debility. An injury voluntarily inflicted on us by others excites our exertions of self-defence or of revenge against the perpetrator of it; but anger does not succeed in any great degree unless our pride is offended; this idea is the maniacal hallucination, the pain of which sometimes produces such violent and general exertions of our muscles and ideas, as to disappoint the revenge we meditate, and vainly to exhaust our sensorial power. Hence angry people, if not further excited by disagreeable language, are liable in an hour or two to become humble, and sorry for their violence, and willing to make greater concessions than required. M. M. Be silent, when you feel yourself angry. Never use loud oaths, violent upbraidings, or strong expressions of countenance, or gesticulations of the arms, or clenched fists; as these by their former associations with anger will contribute to increase it. I have been told of a sergeant or corporal, who began moderately to cane his soldiers, when they were awkward in their exercise, but being addicted to swearing and coarse language, he used soon to enrage himself by his own expressions of anger, till toward the end he was liable to beat the delinquents unmercifully. 18. _Rabies._ Rage. A desire of biting others, most frequently attendant on canine madness. Animals in great pain, as in the colica saturnina, are said to bite the ground they lie upon, and even their own flesh. I have seen patients bite the attendants, and even their own arms, in the epilepsia dolorifica. It seems to be an exertion to relieve pain, as explained in Sect. XXXIV. 1. 3. The dread of water in hydrophobia is occasioned by the repeated painful attempts to swallow it, and is therefore not an essential or original part of the disease called canine madness. See Class III. 1. 1. 15. There is a mania reported to exist in some parts of the east, in which a man is said to run a muck; and these furious maniacs are believed to have induced their calamity by unlucky gaming, and afterwards by taking large quantities of opium; whence the pain of despair is joined with the energy of drunkenness; they are then said to sally forth into the most populous streets, and to wound and slay all they meet, till they receive their own death, which they desire to procure without the greater guilt, as they suppose, of suicide. M. M. When there appears a tendency to bite in the painful epilepsy, the end of a rolled-up towel, or a wedge of soft wood, should be put into the mouth of the patient. As a bullet is said sometimes to be given to a soldier, who is to be severely flogged, that he may by biting it better bear his punishment. 19. _Citta._ A desire to swallow indigestible substances. I once saw a young lady, about ten years of age, who filled her stomach with the earth out of a flower-pot, and vomited it up with small stones, bits of wood, and wings of infects amongst it. She had the bombycinous complexion, and looked like a chlorotic patient, though so young; this generally proceeds from an acid in the stomach. M. M. A vomit. Magnesia alba. Armenian bole. Rhubarb. Bark. Steel. A blister. See Class I. 2. 4. 5. 20. _Cacositia._ Aversion to food. This may arise, without disease of the stomach, from connecting nauseous ideas to our usual food, as by calling a ham a hog's a----. This madness is much inculcated by the stoic philosophy. See Antoninus' Meditations. See two cases of patients who refused to take nourishment, Class III. 1. 2. 1. Aversions to peculiar kinds of food are thus formed early in life by association of some maniacal hallucination with them. I remember a child, who on tasting the gristle of sturgeon, asked what gristle was? And being told it was like the division of a man's nose, received an ideal hallucination; and for twenty years afterwards could not be persuaded to taste sturgeon. The great fear or aversion, which some people experience at the sight of spiders, toads, crickets, and the like, have generally had a similar origin. M. M. Associate agreeable ideas with those which disgust; as call a spider ingenious, a frog clean and innocent; and repress all expressions of disgust by the countenance, as such expressions contribute to preserve, or even to increase, the energy of the ideas associated with them; as mentioned above in Species 17. Ira. 21. _Syphilis imaginaria._ The fear that they are infested with the venereal disease, when they have only deserved it, is a very common insanity amongst modest young men; and is not to be cured without applying artfully to the mind; a little mercury must be given, and hopes of a cure added weekly and gradually by interview or correspondence for six or eight weeks. Many of these patients have been repeatedly salivated without curing the mind! 22. _Psora imaginaria._ I have twice seen an imaginary itch, and twice an imaginary diabætes, where there was not the least vestige of either of those diseases, and once an imaginary deafness, where the patient heard perfectly well. In all these cases the hallucinated idea is so powerfully excited, that it is not to be changed suddenly by occular sensation, or reason. Yet great perseverance in the frequently presenting contrary ideas will sometimes slowly remove this hallucination, or in great length of time oblivion, or forgetfulness, performs a cure, by other means in vain attempted. 23. _Tabes imaginaria._ This imaginary disease, or hallucination, is caused by the supposed too great frequency of parting with the semen, and had long imposed upon the physician as well as the patient, till Mr. John Hunter first endeavoured to shew, that in general the morbid effects of this pollution was in the imagination; and that those were only liable to those effects in general, who had been terrified by the villainous books, which pretend to prevent or to cure it, but which were purposely written to vend some quack medicine. Most of those unhappy patients, whom I have seen, had evidently great impression of fear and self-condemnation on their minds, and might be led to make contradictory complaints in almost any part of the body, and if their confessions could be depended on, had not used this pollution to any great excess. M. M. 1. Assure them if the loss of the semen happens but twice a week, it will not injure them. 2. Marry them. The last is a certain cure; whether the disease be real or imaginary. Cold partial bath, and astringent medicines frequently taken, only recal the mind to the disease, or to the delinquency; and thence increase the imaginary effects and the real cause, if such exists. Mr. ---- destroyed himself to get free from the pain of fear of the supposed ill consequences of self-pollution, without any other apparent disease; whose parents I had in vain advised to marry him, if possible. 24. _Sympathia aliena._ Pity. Our sympathy with the pleasures and pains of others distinguishes men from other animals; and is probably the foundation of what is termed our moral sense and the source of all our virtues. See Sect. XXII. 3. 3. When our sympathy with those miseries of mankind, which we cannot alleviate, rises to excess, the mind becomes its own tormentor; and we add to the aggregate sum of human misery, which we ought to labour to diminish; as in the following eloquent lamentation from Akenside's Pleasures of Imagination, Book II. 1. 200. ----------------Dark, As midnight storms, the scene of human things Appear'd before me; deserts, burning sands, Where the parch'd adder dies; the frozen south; And desolation blasting all the west With rapine and with murder. Tyrant power Here sits enthroned in blood; the baleful charms Of superstition there infect the skies, And turn the sun to horror. Gracious Heaven! What is the life of man? Or cannot these, Not these portents thy awful will suffice? That, propagated thus beyond their scope, They rise to act their cruelties anew In my afflicted bosom, thus decreed The universal sensitive of pain, The wretched heir of evils not its own! A poet of antiquity, whose name I do not recollect, is said to have written a book describing the miseries of the world, and to have destroyed himself at the conclusion of his task. This sympathy, with all sensitive beings, has been carried so far by some individuals, and even by whole tribes, as the Gentoos, as not only to restrain them from killing animals for their support, but even to induce them to permit insects to prey upon their bodies. Such is however the condition of mortality, that the first law of nature is, "Eat or be eaten." We cannot long exist without the destruction of other animal or vegetable beings, either in their mature or their embryon state. Unless the fruits, which surround the seeds of some vegetables, or the honey stolen from them by the bee, may be said to be an exception to this assertion. See Botanic Garden, P. I. Cant. I. l. 278. Note. Hence, from the necessity of our nature, we may be supposed to have a right to kill those creatures, which we want to eat, or which want to eat us. But to destroy even insects wantonly shews an unreflecting mind or a depraved heart. Nevertheless mankind may be well divided into the selfish and the social; that is, into those whose pleasures arise from gratifying their appetites, and those whose pleasures arise from their sympathizing with others. And according to the prevalence of these opposing propensities we value or dislike the possessor of them. In conducting the education of young people, it is a nice matter to inspire them with so much benevolent sympathy, or compassion, as may render them good and amiable; and yet not so much as to make them unhappy at the sight of incurable distress. We should endeavour to make them alive to sympathize with all remediable evils, and at the same time to arm them with fortitude to bear the sight of such irremediable evils, as the accidents of life must frequently present before their eyes. About this I have treated more at large in a plan for the conduct of a boarding school for ladies, which I intend to publish in the course of the next year. 25. _Educatio heroica._ From the kinds and degrees of insanities already enumerated, the reader will probably recollect many more from his own observation; he will perceive that all extraordinary exertions of voluntary action in consequence of some false idea or hallucination, which strongly affects us, may philosophically, though not popularly, be termed an insanity; he will then be liable to divide these voluntary exertions into disagreeable, pernicious, detestable, or into meritorious, delectable, and even amiable, insanities. And will lastly be induced to conceive, that a good education consists in the art of producing such happy hallucinations of ideas, as may be followed by such voluntary exertions, as may be termed meritorious or amiable insanities. The old man of the mountain in Syria, who governed a small nation of people called Assassines, is recorded thus to have educated those of his army who were designed to assassinate the princes with whom he was at war. A young man of natural activity was chosen for the purpose, and thrown into a deep sleep by opium mixed with his food; he was then carried into a garden made to represent the paradise of Mahomet, with flowers of great beauty and fragrance, fruits of delicious flavor, and beautiful houries beckoning him into the shades. After a while, on being a second time stupified with opium, the young enthusiast was reconveyed to his apartment; and on the next day was assured by a priest, that he was designed for some great exploit, and that by obeying the commands of their prince, immortal happiness awaited him. Hence it is easy to collect how the first impressions made on us by accidental circumstances in our infancy continue through life to bias our affections, or mislead our judgments. One of my acquaintance can trace the origin of his own energies of action from some such remote sources; which justifies the observation of M. Rousseau, that the seeds of future virtues or vices are oftener sown by the mother, than the tutor. * * * * * ORDO II. _Decreased Volition._ GENUS I. _With decreased Actions of the Muscles._ Our muscles become fatigued by long contraction, and cease for a time to be excitable by the will; owing to exhaustion of the sensorial power, which resides in them. After a short interval of relaxation the muscle regains its power of voluntary contraction; which is probably occasioned by a new supply of the spirit of animation. In weaker people these contractions cease sooner, and therefore recur more frequently, and are attended with shorter intervals of relaxation, as exemplified in the quickness of the pulse in fevers with debility, and in the tremors of the hands of aged or feeble people. After a common degree of exhaustion of the sensorial power in a muscle, it becomes again gradually restored by the rest of the muscle; and even accumulated in those muscles, which are most frequently used; as in those which constitute the capillaries of the skin after having been rendered torpid by cold. But in those muscles, which are generally obedient to volition, as those of locomotion, though their usual quantity of sensorial power is restored by their quiescence, or in sleep (for sleep affects these parts of the system only), yet but little accumulation of it succeeds. And this want of accumulation of the sensorial power in these muscles, which are chiefly subservient to volition, explains to us one cause of their greater tendency to paralytic affection. It must be observed, that those parts of the system, which have been for a time quiescent from want of stimulus, as the vessels of the skin, when exposed to cold, acquire an accumulation of sensorial power during their inactivity; but this does not happen at all, or in much less quantity, from their quiescence after great expenditure of sensorial power by a previous excessive stimulus, as after intoxication. In this case the muscles or organs of sense gradually acquire their natural quantity of sensorial power, as after sleep; but not an accumulation or superabundance of it. And by frequent repetitions of exhaustion by great stimulus, these vessels cease to acquire their whole natural quantity of sensorial power; as in the schirrous stomach, and schirrous liver, occasioned by the great and frequent stimulus of vinous spirit; which may properly be termed irritative paralysis of those parts of the system. In the same manner in common palsies the inaction of the paralytic muscle seems not to be owing to defect of the stimulus of the will, but to exhaustion of sensorial power. Whence it frequently follows great exertion, as in Sect. XXXIV. 1. 7. Thus some parts of the system may cease to obey the will, as in common paralysis; others may cease to be obedient to sensation, as in the impotency of age; others to irritation, as in schirrous viscera; and others to association, as in impediment of speech; yet though all these may become inexcitable, or dead, in respect to that kind of stimulus, which has previously exhausted them, whether of volition, or sensation, or irritation, or association, they may still in many cases be excited by the others. SPECIES. 1. _Lassitudo._ Fatigue or weariness after much voluntary exertion. From the too great expenditure of sensorial power the muscles are with difficulty brought again into voluntary contraction; and seem to require a greater quantity or energy of volition for this purpose. At the same time they still remain obedient to the stimulus of agreeable sensation, as appears in tired dancers finding a renovation of their aptitude to motion on the acquisition of an agreeable partner; or from a tired child riding on a gold-headed cane, as in Sect. XXXIV. 2. 6. These muscles are likewise still obedient to the sensorial power of association, because the motions, when thus excited, are performed in their designed directions, and are not broken into variety of gesticulation, as in St. Vitus's dance. A lassitude likewise frequently occurs with yawning at the beginning of ague-fits; where the production of sensorial power in the brain is less than its expenditure. For in this case the torpor may either originate in the brain, or the torpor of some distant parts of the system may by sympathy affect the brain, though in a less proportionate degree than the parts primarily affected. 2. _Vacillatio senilis._ Some elderly people acquire a see-saw motion of their bodies from one side to the other, as they sit, like the oscillation of a pendulum. By these motions the muscles, which preserve the perpendicularity of the body, are alternately quiescent, and exerted; and are thus less liable to fatigue or exhaustion. This therefore resembles the tremors of old people above mentioned, and not those spasmodic movements of the face or limbs, which are called tricks, described in Class IV. 1. 3. 2. which originate from excess of sensorial power, or from efforts to relieve disagreeable sensation, and are afterwards continued by habit. 3. _Tremor senilis._ Tremor of old age consists of a perpetual trembling of the hands, or of the head, or of other muscles, when they are exerted; and is erroneously called paralytic; and seems owing to the small quantity of animal power residing in the muscular fibres. These tremors only exist when the affected muscles are excited into action, as in lifting a glass to the mouth, or in writing, or in keeping the body upright; and cease again, when no voluntary exertion is attempted, as in lying down. Hence these tremors evidently originate from the too quick exhaustion of the lessened quantity of the spirit of animation. So many people tremble from fear or anger, when too great a part of the sensorial power is exerted on the organs of sense, so as to deprive the muscles, which support the body erect, of their due quantity. 4. _Brachiorum paralysis._ A numbness of the arms is a frequent symptom in hydrops thoracis, as explained in Class I. 2. 3. 14. and in Sect. XXIX. 5. 2.; it also accompanies the asthma dolorificum, Class III. 1. 1. 11. and is owing probably to the same cause in both. In the colica saturnina a paralysis affects the wrists, as appears on the patient extending his arm horizontally with the palm downwards, and is often attended with a tumor on the carpal or metacarpal bones. See Class IV. 1. 2. 10. Mr. M----, a miner and well-sinker, about three years ago, lost the power of contracting both his thumbs; the balls or muscles of the thumbs are much emaciated, and remain paralytic. He ascribes his disease to immersing his hands too long in cold water in the execution of his business. He says his hands had frequently been much benumbed before, so that he could not without difficulty clench them; but that they recovered their motion, as soon as they began to glow, after he had dried and covered them. In this case there existed two injurious circumstances of different kinds; one the violent and continued action of the muscles, which destroys by exhausting the sensorial power; and the other, the application of cold, which destroys by defect of stimulus. The cold seems to have contributed to the paralysis by its long application, as well as the continued exertion; but as during the torpor occasioned by the exposure to cold, if the degree of it be not so great as to extinguish life, the sensorial power becomes accumulated; there is reason to believe, that the exposing a paralytic limb to the cold for a certain time, as by covering it with snow or iced water for a few minutes, and then covering it with warm flannel, and this frequently repeated, might, by accumulation of sensorial power, contribute to restore it to a state of voluntary excitability. As this accumulation of sensorial power, and consequent glow, seems, in the present case, several times to have contributed to restore the numbness or inability of those muscles, which at length became paralytic. See Class I. 2. 3. 21. M. M. Ether externally. Friction. Saline warm bath. Electricity. 5. _Raucedo paralytica._ Paralytic hoarseness consists in the almost total loss of voice, which sometimes continues for months, or even years, and is occasioned by inability or paralysis of the recurrent nerves, which serve the muscles of vocality, by opening or closing the larynx. The voice generally returns suddenly, even so as to alarm the patient. A young lady, who had many months been affected with almost a total loss of voice, and had in vain tried variety of advice, recovered her voice in an instant, on some alarm as she was dancing at an assembly. Was this owing to a greater exertion of volition than usual? like the dumb young man, the son of Croesus, who is related to have cried out, when he saw his father's life endangered by the sword of his enemy, and to have continued to speak ever afterwards. Two young ladies in this complaint seemed to be cured by electric shocks passed through the larynx every day for a fortnight. See Raucedo catarrhalis, Class II. 1. 3. 5. M. M. An emetic. Electric shocks. Mustard-seed, a large spoonful swallowed whole, or a little bruised, every morning. Valerian. Burnt sponge. Blisters on each side of the larynx. Sea-bathing. A gargle of decoction of seneca. Friction. Frequent endeavours to shout and sing. 6. _Vesicæ urinariæ paralysis._ Paralysis of the bladder is frequently a symptom in inirritative fever; in this case the patient makes no water for a day or two; and the tumor of the bladder distended with urine may be seen by the shape of the abdomen, as if girt by a cord below the navel, or distinguished by the hand. Many patients in this situation make no complaint, and suffer great injury by the inattention of their attendants; the water must be drawn off once or twice a day by means of a catheter, and the region of the bladder gently pressed by the hand, whilst the patient be kept in a sitting or erect posture. M. M. Bark. Wine. Opium, a quarter of a grain every six hours. Balsam of copaiva or of Peru. Tincture of cantharides 20 drops twice a day, or repeated small blisters. 7. _Recti paralysis._ Palsy of the rectum. The rectum intestinum, like the urinary bladder in the preceding article, possesses voluntary power of motion; though these volitions are at times uncontrollable by the will, when the acrimony of the contained feces, or their bulk, stimulate it to a greater degree. Hence it happens, that this part is liable to lose its voluntary power by paralysis, but is still liable to be stimulated into action by the contained feces. This frequently occurs in fevers, and is a bad sign as a symptom of general debility; and it is the sensibility of the muscular fibres of this and of the urinary bladder remaining, after the voluntarity has ceased, which occasions these two reservoirs so soon to regain, as the fever ceases, their obedience to volition; because the paralysis is thus shewn to be less complete in those cases than in common hemiplegia; as in the latter the sense of touch, though perhaps not the sense of pain, is generally destroyed in the paralytic limb. M. M. A sponge introduced within the sphincter ani to prevent the constant discharge, which should have a string put through it, by which it may be retracted. 8. _Paresis voluntaria._ Indolence; or inaptitude to voluntary action. This debility of the exertion of voluntary efforts prevents the accomplishment of all great events in life. It often originates from a mistaken education, in which pleasure or flattery is made the immediate motive of action, and not future advantage; or what is termed duty. This observation is of great value to those, who attend to the education of their own children. I have seen one or two young married ladies of fortune, who perpetually became uneasy, and believed themselves ill, a week after their arrival in the country, and continued so uniformly during their stay; yet on their return to London or Bath immediately lost all their complaints, and this repeatedly; which I was led to ascribe to their being in their infancy surrounded with menial attendants, who had flattered them into the exertions they then used. And that in their riper years, they became torpid for want of this stimulus, and could not amuse themselves by any voluntary employment; but required ever after, either to be amused by other people, or to be flattered into activity. This I suppose, in the other sex, to have supplied one source of ennui and suicide. 9. _Catalepsis_ is sometimes used for fixed spasmodic contractions or tetanus, as described in Sect. XXXIV. 1. 5. and in Class III. 1. 1. 13. but is properly simply an inaptitude to muscular motion, the limbs remaining in any attitude in which they are placed. One patient, whom I saw in this situation, had taken much mercury, and appeared universally torpid. He sat in a chair in any posture he was put, and held a glass to his mouth for many minutes without attempting to drink, or withdrawing his hand. He never spoke, and it was at first necessary to compel him to drink broth; he recovered in a few weeks without relapse. 10. _Hemiplegia._ Palsy of one side consists in the total disobedience of the affected muscles to the power of volition. As the voluntary motions are not perpetually exerted, there is little sensorial power accumulated during their quiescence, whence they are less liable to recover from torpor, and are thus more frequently left paralytic, or disobedient to the power of volition, though they are sometimes still alive to painful sensation, as to the prick of a pin, and to heat; also to irritation, as in stretching and yawning; or to electric shocks. Where the paralysis is complete the patient seems gradually to learn to use his limbs over again by repeated efforts, as in infancy; and, as time is required for this purpose, it becomes difficult to know, whether the cure is owing to the effect of medicines, or to the repeated efforts of the voluntary power. The dispute, whether the nerves decussate or cross each other before they leave the cavities of the skull or spine, seems to be decided in the affirmative by comparative anatomy; as the optic nerves of some fish have been shewn evidently to cross each other; as seen by Haller, Elem. Physiol. t. v. p. 349. Hence the application of blisters, or of ether, or of warm fomentations, should be on the side of the head opposite to that of the affected muscles. This subject should nevertheless be nicely determined, before any one should trepan for the hydrocephalus internus, when the disease is shewn to exist only on one side of the brain, by a squinting affecting but one eye; as proposed in Class I. 2. 5. 4. Dr. Sommering has shewn, that a true decussation of the optic nerves in the human subject actually exists, Elem. of Physiology by Blumenbach, translated by C. Caldwell, Philadelphia. This further appears probable from the oblique direction and insertion of each optic nerve, into the side of the eye next to the nose, in a direct line from the opposite side of the brain. The vomiting, which generally attends the attack of hemiplegia, is mentioned in Sect. XX. 8. and is similar to that attending vertigo in sea-sickness, and at the commencement of some fevers. Black stools sometimes attend the commencement of hemiplegia, which is probably an effusion of blood from the biliary duct, where the liver is previously affected; or some blood may be derived to the intestines by its escaping from the vena cava into the receptacle of chyle during the distress of the paralytic attack; and may be conveyed from thence into the intestines by the retrograde motions of the lacteals; as probably sometimes happens in diabætes. See Sect. XXVII. 2. Palsy of one side of the face is mentioned in Class II. 1. 4. 6. Paralysis of the lacteals, of the liver, and of the veins, which are described in Sect. XXVIII. XXX. and XXVII. do not belong to this class, as they are not diseases of voluntary motions. M. M. The electric sparks and shocks, if used early in the disease, are frequently of service. A purge of aloes, or calomel. A vomit. Blister. Saline draughts. Then the bark. Mercurial ointment or sublimate, where the liver is evidently diseased; or where the gutta rosea has previously existed. Sudden alarm. Frequent voluntary efforts. Externally ether. Volatile alcali. Fomentation on the head. Friction. When children, who have suffered an hemiplegia, begin to use the affected arm, the other hand should be tied up for half an hour three or four times a day; which obliges them at their play to use more frequent voluntary efforts with the diseased limb, and thus sooner to restore the dissevered associations of motion. Dr. J. Alderson has lately much recommended the leaves of rhus toxicodendon (sumach), from one gr. to iv. of the dried powder to be taken three or four times a day. Essay on Rhus Toxic. Johnson, London, 1793. But it is difficult to know what medicine is of service, as the movements of the muscles must be learned, as in infancy, by frequent efforts. 11. _Paraplegia._ A palsy of the lower half of the body divided horizontally. Animals may be conceived to have double bodies, one half in general resembling so exactly the other, and being supplied with separate sets of nerves; this gives rise to hemiplegia, or palsy of one half of the body divided vertically; but the paraplegia, or palsy of the lower parts of the system, depends on an injury of the spinal marrow, or that part of the brain which is contained in the vertebræ of the back; by which all the nerves situated below the injured part are deprived of their nutriment, or precluded from doing their proper offices; and the muscles, to which they are derived, are in consequence disobedient to the power of volition. This sometimes occurs from an external injury, as a fall from an eminence; of which I saw a deplorable instance, where the bladder and rectum, as well as the lower limbs, were deprived of so much of their powers of motion, as depended on volition or sensation; but I suppose not of that part of it, which depends on irritation. In the same manner as the voluntary muscles in hemiplegia are sometimes brought into action by irritation, as in stretching or pendiculation, described in Sect. VII. 1. 3. But the most frequent cause of paraplegia is from a protuberance of one of the spinal vertebræ; which is owing to the innutrition or softness of bones, described in Class I. 2. 2. 17. The cure of this deplorable disease is frequently effected by the stimulus of an issue placed on each side of the prominent spine, as first published by Mr. Pott. The other means recommended in softness of bones should also be attended to; both in respect to the internal medicines, and to the mechanical methods of supporting, or extending the spine; which last, however, in this case requires particular caution. 12. _Somnus._ In sleep all voluntary power is suspended, see Sect. XVIII. An unusual quantity of sleep is often produced by weakness. In this case small doses of opium, wine, and bark, may be given with advantage. For the periods of sleep, see Class IV. 2. 4. 1. The subsequent ingenious observations on the frequency of the pulse, which sometimes occurs in sleep, are copied from a letter of Dr. Currie of Liverpool to the author. "Though rest in general perhaps renders the healthy pulse slower, yet under certain circumstances the contrary is the truth. A full meal without wine or other strong liquor does not increase the frequency of my pulse, while I sit upright, and have my attention engaged. But if I take a recumbent posture after eating, my pulse becomes more frequent, especially if my mind be vacant, and I become drowsy; and, if I slumber, this increased frequency is more considerable with heat and flushing. "This I apprehend to be a general truth. The observation may be frequently made upon children; and the restless and feverish nights experienced by many people after a full supper are, I believe, owing to this cause. The supper occasions no inconvenience, whilst the person is upright and awake; but, when he lies down and begins to sleep, especially if he does not perspire, the symptoms above mentioned occur. Which may be thus explained in part from your principles. When the power of volition is abolished, the other sensorial actions are increased. In ordinary sleep this does not occasion increased frequency of the pulse; but where sleep takes place during the process of digestion, the digestion itself goes on with increased rapidity. Heat is excited in the system faster than it is expended; and operating on the sensitive actions, it carries them beyond the limitation of pleasure, producing, as is common in such cases, increased frequency of pulse. "It is to be observed, that in speaking of the heat generated under these circumstances, I do not allude to any chemical evolution of heat from the food in the process of digestion. I doubt if this takes place to any considerable degree, for I do not observe that the parts incumbent on the stomach are increased in heat during the most hurried digestion. It is on some parts of the surface, but more particularly on the extremities of the body, that the increased heat excited by digestion appears, and the heat thus produced arises, as it should seem, from the sympathy between the stomach and the vessels of the skin. The parts most affected are the palms of the hands and the soles of the feet. Even there the thermometer seldom rises above 97 or 98 degrees, a temperature not higher than that of the trunk of the body; but three or four degrees higher than the common temperature of these parts, and therefore producing an uneasy sensation of heat, a sensation increased by the great sensibility of the parts affected. "That the increased heat excited by digestion in sleep is the cause of the accompanying fever, seems to be confirmed by observing, that if an increased expenditure of heat accompanies the increased generation of it (as when perspiration on the extremities or surface attends this kind of sleep) the frequent pulse and flushed countenance do not occur, as I know by experiment. If, during the feverish sleep already mentioned, I am awakened, and my attention engaged powerfully, my pulse becomes almost immediately slower, and the fever gradually subsides." From these observations of Dr. Currie it appears, that, while in common sleep the actions of the heart, arteries, and capillaries, are strengthened by the accumulation of sensorial power during the suspension of voluntary action, and the pulse in consequence becomes fuller and slower; in the feverish sleep above described the actions of the heart, arteries, and capillaries, are quickened as well as strengthened by their consent with the increased actions of the stomach, as well as by the stimulus of the new chyle introduced into the circulation. For the stomach, and all other parts of the system, being more sensible and more irritable during sleep, Sect. XVIII. 15. and probably more ready to act from association, are now exerted with greater velocity as well as strength, constituting a temporary fever of the sensitive irritated kind, resembling the fever excited by wine in the beginning of intoxication; or in some people by a full meal in their waking hours. Sect. XXXV. 1. On waking, this increased sensibility and irritability of the system ceases by the renewed exertions of volition; in the same manner as more violent exertions of volition destroy greater pains; and the pulse in consequence subsides along with the increase of heat; if more violent efforts of volition are exerted, the system becomes still less affected by sensation or irritation. Hence the fever and vertigo of intoxication are lessened by intense thinking, Sect. XXI. 8; and insane people are known to bear the pain of cold and hunger better than others, Sect. XXXIV. 2. 5; and lastly, if greater voluntary efforts exist, as in violent anger or violent exercise, the whole system is thrown into more energetic action, and a voluntary fever is induced, as appears by the red skin, quickened pulse, and increase of heat; whence dropsies and fevers with debility are not unfrequently removed by insanity. Hence the exertion of the voluntary power in its natural degree diminishes the increased sensibility, and irritability, and probably the increased associability, which occurs during sleep; and thus reduces the frequency of the pulse in the feverish sleep after a full meal. In its more powerful state of exertion, it diminishes or destroys sensations and irritations, which are stronger than natural, as in intoxication, or which precede convulsions, or insanity. In its still more powerful degree, the superabundance of this sensorial power actuates and invigorates the whole moving system, giving strength and frequency to the pulse, and an universal glow both of colour and of heat, as in violent anger, or outrageous insanities. If, in the feverish sleep above described, the skin becomes cooled by the evaporation of much perspirable matter, or by the application of cooler air, or thinner clothes, the actions of the cutaneous capillaries are lessened by defect of the stimulus of heat, which counteracts the increase of sensibility during sleep, and the pulsations of the heart and arteries become slower from the lessened stimulus of the particles of blood thus cooled in the cutaneous and pulmonary vessels. Hence the admission of cold air, or ablution with subtepid or with cold water, in fevers with hot skin, whether they be attended with arterial strength, or arterial debility, renders the pulse slower; in the former case by diminishing the stimulus of the blood, and in the latter by lessening the expenditure of sensorial power. See Suppl. I. 8. and 15. 13. _Incubus._ The night-mare is an imperfect sleep, where the desire of locomotion is vehement, but the muscles do not obey the will; it is attended with great uneasiness, a sense of suffocation, and frequently with fear. It is caused by violent fatigue, or drunkenness, or indigestible food, or lying on the back, or perhaps from many other kinds of uneasiness in our sleep, which may originate either from the body or mind. Now as the action of respiration is partly voluntary, this complaint may be owing to the irritability of the system being too small to carry on the circulation of the blood through the lungs during sleep, when the voluntary power is suspended. Whence the blood may accumulate in them, and a painful oppression supervene; as in some hæmorrhages of the lungs, which occur during sleep; and in patients much debilitated by fevers. See Somnus interruptus, Class I. 2. 1. 3. and I. 2. 1. 9. Great fatigue with a full supper and much wine, I have been well informed by one patient, always produced this disease in himself to a great degree. Now the general irritability of the system is much decreased by fatigue, as it exhausts the sensorial power; and secondly, too much wine and stimulating food will again diminish the irritability of some parts of the system, by employing a part of the sensorial power, which is already too small, in digesting a great quantity of aliment; and in increasing the motions of the organs of sense in consequence of some degree of intoxication, whence difficulty of breathing may occur from the inirritability of the lungs, as in Class I. 2. 1. 3. M. M. To sleep on a hard bed with the head raised. Moderate supper. The bark. By sleeping on a harder bed the patient will turn himself more frequently, and not be liable to sleep too profoundly, or lie too long in one posture. To be awakened frequently by an alarm clock. 14. _Lethargus._ The lethargy is a slighter apoplexy. It is supposed to originate from universal pressure on the brain, and is said to be produced by compressing the spinal marrow, where there is a deficiency of the bone in the spina bifida. See Sect. XVIII. 20. Whereas in the hydrocephalus there is only a partial pressure of the brain; and probably in nervous fevers with stupor the pressure on the brain may affect only the nerves of the senses, which lie within the skull, and not those nerves of the medulla oblongata, which principally contribute to move the heart and arteries; whence in the lethargic or apoplectic stupor the pulse is slow as in sleep, whereas in nervous fever the pulse is very quick and feeble, and generally so in hydrocephalus. In cases of obstructed kidneys, whether owing to the tubuli uriniferi being totally obstructed by calculous matter, or by their paralysis, a kind of drowsiness or lethargy comes on about the eighth or ninth day, and the patient gradually sinks. See Class I. 1. 3. 9. 15. _Syncope epileptica_, is a temporary apoplexy, the pulse continuing in its natural state, and the voluntary power suspended. This terminates the paroxysms of epilepsy. When the animal power is much exhausted by the preceding convulsions, so that the motions from sensation as well as those from volition are suspended; in a quarter or half an hour the sensorial power becomes restored, and if no pain, or irritation producing pain, recurs, the fit of epilepsy ceases; if the pain recurs, or the irritation, which used to produce it, a new fit of convulsion takes place, and is succeeded again by a syncope. See Epilepsy, Class III. 1. 1. 7. 16. _Apoplexia._ Apoplexy may be termed an universal palsy, or a permanent sleep. In which, where the pulse is weak, copious bleeding must be injurious; as is well observed by Dr. Heberden, Trans. of the College. Mr. ----, about 70 years of age, had an apoplectic seizure. His pulse was strong and full. One of the temporal arteries was opened, and about ten ounces of blood suddenly taken from it. He seemed to receive no benefit from this operation; but gradually sunk, and lived but a day or two. If apoplexy arises from the pressure of blood extravasated on the brain, one moderate venesection may be of service to prevent the further effusion of blood; but copious venesection must be injurious by weakening the patient; since the effused blood must have time, as in common vibices or bruises, to undergo a chemico-animal process, so to change its nature as to fit it for absorption; which may take two or three weeks, which time a patient weakened by repeated venesection or arteriotomy may not survive. Mrs. ----, about 40 years old, had an apoplectic seizure after great exertion from fear; she had lain about 24 hours without speech, or having swallowed any liquid. She was then forcibly raised in bed, and a spoonful of solution of aloes in wine put into her mouth, and the end of the spoon withdrawn, that she might more easily swallow the liquid.--This was done every hour, with broth, and wine and water intervening, till evacuations were procured; which with other means had good effect, and she recovered, except that a considerable degree of hemiplegia remained, and some imperfection of her speech. Many people, who have taken so much vinous spirit as to acquire the temporary apoplexy of intoxication, and are not improperly said to be dead-drunk, have died after copious venesection, I suppose in consequence of it. I once saw at a public meeting two gentlemen in the drunken apoplexy; they were totally insensible with low pulse, on this account they were directed not to lose blood, but to be laid on a bed with their heads high, and to be turned every half hour; as soon as they could swallow, warm tea was given them, which evacuated their stomachs, and they gradually recovered, as people do from less degrees of intoxication. M. M. Cupping on the occiput. Venesection once in moderate quantity. Warm fomentations long continued and frequently repeated on the shaved head. Solution of aloes. Clysters with solution of aloe and oil of amber. A blister on the spine. An emetic. Afterwards the bark, and small doses of chalybeates. Small electric shocks through the head. Errhines. If small doses of opium? 17. _Mors a frigore._ Death from cold. The unfortunate travellers, who almost every winter perish in the snow, are much exhausted by their efforts to proceed on their journey, as well as benumbed by cold. And as much greater exercise can be borne without fatigue in cold weather than in warm; because the excessive motions of the cutaneous vessels are thus prevented, and the consequent waste of sensorial power; it may be inferred, that the fatigued traveller becomes paralytic from violent exertion as well as by the application of cold. Great degrees of cold affect the motions of those vessels most, which have been generally excited into action by irritation; for when the feet are much benumbed by cold, and painful, and at the same time almost insensible to the touch of external objects, the voluntary muscles retain their motions, and we continue to walk on; the same happens to the fingers of children in throwing snow-balls, the voluntary motions of the muscles continue, though those of the cutaneous vessels are benumbed into inactivity. Mr. Thompson, an elderly gentleman of Shrewsbury, was seized with hemiplegia in the cold bath; which I suppose might be owing to some great energy of exertion, as much as to the coldness of the water. As in the instance given of Mr. Nairn, who, by the exertion to save his relation, perished himself. See Sect. XXXIV. 1. 7. Whence I conclude, that though heat is a fluid necessary to muscular motion, both perhaps by its stimulus, and by its keeping the minute component parts of the ultimate fibrils of the muscles or organs of sense at a proper distance from each other; yet that paralysis, properly so called, is the consequence of exhaustion of sensorial power by exertion. And that the accumulations of it during the torpor of the cutaneous vessels by exposure to cold, or of some internal viscus in the cold fits of agues, are frequently instrumental in recovering the use of paralytic limbs, or of the motions of other paralytic parts of the system. See Spec. 4. of this genus. Animal bodies resist the power of cold probably by their exertions in consequence of the pain of cold, see Botan. Gard. V. 1. additional note xii. But if these increased exertions be too violent, so as to exhaust the sensorial power in producing unnecessary motions, the animal will probably sooner perish. Thus a moderate quantity of wine or spirit repeated at proper intervals of time might be of service to those, who are long exposed to excessive cold, both by increasing the action of the capillary vessels, and thus producing heat, and perhaps by increasing in some degree the secretion of sensorial power in the brain. But the contrary must happen when taken immoderately, and not at due intervals. A well attested history was once related to me of two men, who set out on foot to travel in the snow, one of whom drank two or three glasses of brandy before they began their journey, the other contented himself with his usual diet and potation; the former of whom perished in spite of any assistance his companion could afford him; and the other performed his journey with safety. In this case the sensorial power was exhausted by the unnecessary motions of incipient intoxication by the stimulus of the brandy, as well as by the exertions of walking; which so weakened the dram-drinker, that the cold sooner destroyed him; that is, he had not power to produce sufficient muscular or arterial action, and in consequence sufficient heat, to supply the great expenditure of it. Hence the capillaries of the skin first cease to act, and become pale and empty; next those which are immediately associated with them, as the extremities of the pulmonary artery, as happens on going into the cold bath. By the continued inaction of these parts of the vascular system the blood becomes accumulated in the internal arteries, and the brain is supposed to be affected by its compression; because these patients are said to sleep, or to become apoplectic, before they die. I overtook a fishman asleep on his panniers on a very cold frosty night, but on waking him he did not appear to be in any degree of stupor. See Class I. 2. 2. 1. When travellers are benighted in deep snow, they might frequently be saved by covering themselves in it, except a small aperture for air; in which situation the lives of hares, sheep, and other animals, are so often preserved. The snow, both in respect to its component parts, and to the air contained in its pores, is a bad conductor of heat, and will therefore well keep out the external cold; and as the water, when part of it dissolves, is attracted into the pores of the remainder of it, the situation of an animal beneath it is perfectly dry; and, if he is in contact with the earth, he is in a degree of heat between 48, the medium heat of the earth, and 32, the freezing point; that is, in 40 degrees of heat, in which a man thus covered will be as warm as in bed. See Botan. Garden, V. II. notes on Anemone, Barometz, and Muschus. If these facts were more generally understood, it might annually save the lives of many. After any part of the vascular system of the body has been long exposed to cold, the sensorial power is so much accumulated in it, that on coming into a warm room the pain of hotach is produced, and inflammation, and consequent mortification, owing to the great exertion of those vessels, when again exposed to a moderate degree of warmth. See Sect. XII. 5. Whence the propriety of applying but very low degrees of heat to limbs benumbed with cold at first, as of snow in its state of dissolving, which is at 32 degrees of heat, or of very cold water. A French writer has observed, that if frozen apples be thawed gradually by covering them with thawing snow, or immersing them in very cold water, that they do not lose their taste; if this fact was well ascertained, it might teach us how to preserve other ripe fruits in ice-houses for winter consumption. * * * * * ORDO II. _Decreased Volition._ GENUS II. _With decreased Actions of the Organs of Sense._ SPECIES. 1. _Recollectionis jactura._ Loss of recollection. This is the defect of memory in old people, who forget the actions of yesterday, being incapable of voluntary recollection, and yet remember those of their youth, which by frequent repetition are introduced by association or suggestion. This is properly the paralysis of the mind; the organs of sense do not obey the voluntary power; that is, our ideas cannot be recollected, or acted over again by the will. After an apoplectic attack the patients, on beginning to recover, find themselves most at a loss in recollecting proper names of persons or places; as those words have not been so frequently associated with the ideas they stand for, as the common words of a language. Mr. ----, a man of strong mind, of a short necked family, many of whom had suffered by apoplexy, after an apoplectic fit on his recovering the use of speech, after repeated trials to remember the name of a person or place, applauded himself, when he succeeded, with such a childish smile on the partial return of his sagacity, as very much affected me.--Not long, alas! to return; for another attack in a few weeks destroyed the whole. I saw a child after the small-pox, which was left in this situation; it was lively, active, and even vigorous; but shewed that kind of surprise, which novelty excites, at every object it viewed; and that as often as it viewed it. I never heard the termination of the case. 2. _Stultitia voluntaria._ Voluntary folly. The absence of voluntary power and consequent incapacity to compare the ideas of present and future good. Brute animals may be said to be in this situation, as they are in general excited into action only by their present painful or pleasurable sensations. Hence though they are liable to surprise, when their passing trains of ideas are dissevered by violent stimuli; yet are they not affected with wonder or astonishment at the novelty of objects; as they possess but in a very inferior degree, that voluntary power of comparing the present ideas with those previously acquired, which distinguishes mankind; and is termed analogical reasoning, when deliberatively exerted; and intuitive analogy, when used without our attention to it, and which always preserves our hourly trains of ideas consistent with truth and nature. See Sect. XVII. 3. 7. 3. _Credulitas._ Credulity. Life is short, opportunities of knowledge rare; our senses are fallacious, our reasonings uncertain, mankind therefore struggles with perpetual error from the cradle to the coffin. He is necessitated to correct experiment by analogy, and analogy by experiment; and not always to rest satisfied in the belief of facts even with this two-fold testimony, till future opportunities, or the observations of others, concur in their support. Ignorance and credulity have ever been companions, and have misled and enslaved mankind; philosophy has in all ages endeavoured to oppose their progress, and to loosen the shackles they had imposed; philosophers have on this account been called unbelievers: unbelievers of what? of the fictions of fancy, of witchcraft, hobgobblins, apparitions, vampires, fairies; of the influence of stars on human actions, miracles wrought by the bones of saints, the flights of ominous birds, the predictions from the bowels of dying animals, expounders of dreams, fortune-tellers, conjurors, modern prophets, necromancy, cheiromancy, animal magnetism, with endless variety of folly? These they have disbelieved and despised, but have ever bowed their hoary heads to Truth and Nature. Mankind may be divided in respect to the facility of their belief or conviction into two classes; those, who are ready to assent to single facts from the evidence of their senses, or from the serious assertions of others; and those, who require analogy to corroborate or authenticate them. Our first knowledge is acquired by our senses; but these are liable to deceive us, and we learn to detect these deceptions by comparing the ideas presented to us by one sense with those presented by another. Thus when we first view a cylinder, it appears to the eye as a flat surface with different shades on it, till we correct this idea by the sense of touch, and find its surface to be circular; that is, having some parts gradually receding further from the eye than others. So when a child, or a cat, or a bird, first sees its own image in a looking-glass, it believes that another animal exists before it, and detects this fallacy by going behind the glass to examine, if another tangible animal really exists there. Another exuberant source of error consists in the false notions, which we receive in our early years from the design or ignorance of our instructors, which affect all our future reasoning by their perpetual intrusions; as those habits of muscular actions of the face or limbs, which are called tricks, when contracted in infancy continue to the end of our lives. A third great source of error is the vivacity of our ideas of imagination, which perpetually intrude themselves by various associations, and compose the farrago of our dreams; in which, by the suspension of volition, we are precluded from comparing the ideas of one sense with those of another, or the incongruity of their successions with the usual course of nature, and thus to detect their fallacy. Which we do in our waking hours by a perpetual voluntary exertion, a process of the mind above mentioned, which we have termed intuitive analogy. Sect. XVII. 3. 7. This analogy presupposes an acquired knowledge of things, hence children and ignorant people are the most credulous, as not possessing much knowledge of the usual course of nature; and secondly, those are most credulous, whose faculty of comparing ideas, or the voluntary exertion of it, is slow or imperfect. Thus if the power of the magnetic needle of turning towards the north, or the shock given by touching both sides of an electrized coated jar, was related for the first time to a philosopher, and to an ignorant person; the former would be less ready to believe them, than the latter; as he would find nothing similar in nature to compare them to, he would again and again repeat the experiment, before he would give it his entire credence; till by these repetitions it would cease to be a single fact, and would therefore gain the evidence of analogy. But the latter, as having less knowledge of nature, and less facility of voluntary exertion, would more readily believe the assertions of others, or a single fact, as presented to his own observation. Of this kind are the bulk of mankind; they continue throughout their lives in a state of childhood, and have thus been the dupes of priests and politicians in all countries and in all ages of the world. In regard to religious matters, there is an intellectual cowardice instilled into the minds of the people from their infancy; which prevents their inquiry: credulity is made an indispensable virtue; to inquire or exert their reason in religious matters is denounced as sinful; and in the catholic church is punished with more severe penances than moral crimes. But in respect to our belief of the supposed medical facts, which are published by variety of authors; many of whom are ignorant, and therefore credulous; the golden rule of David Hume may be applied with great advantage. "When two miraculous assertions oppose each other, believe the less miraculous." Thus if a person is said to have received the small-pox a second time, and to have gone through all the stages of it, one may thus reason: twenty thousand people have been exposed to the variolous contagion a second time without receiving the variolous fever, to every one who has been said to have thus received it; it appears therefore less miraculous, that the assertor of this supposed fact has been deceived, or wishes to deceive, than that it has so happened contrary to the long experienced order of nature. M. M. The method of cure is to increase our knowledge of the laws of nature, and our habit of comparing whatever ideas are presented to us with those known laws, and thus to counteract the fallacies of our senses, to emancipate ourselves from the false impressions which we have imbibed in our infancy, and to set the faculty of reason above that of imagination. * * * * * _The Orders and Genera of the Fourth Class of Diseases._ CLASS IV. DISEASES OF ASSOCIATION. ORDO I. _Increased Associate Motions._ GENERA. 1. Catenated with irritative motions. 2. Catenated with sensitive motions. 3. Catenated with voluntary motions. 4. Catenated with external influences. ORDO II. _Decreased Associate Motions._ GENERA. 1. Catenated with irritative motions. 2. Catenated with sensitive motions. 3. Catenated with voluntary motions. 4. Catenated with external influences. ORDO III. _Retrograde Associate Motions._ GENERA. 1. Catenated with irritative motions. 2. Catenated with sensitive motions. 3. Catenated with voluntary motions. 4. Catenated with external influences. * * * * * _The Orders, Genera, and Species, of the Fourth Class of Diseases._ * * * * * CLASS IV. DISEASES OF ASSOCIATION. ORDO I. _Increased Associate Motions._ GENUS I. _Catenated with Irritative Motions._ SPECIES. 1. _Rubor vultûs pransorum._ Flushing of the face after dinner. 2. _Sudor stragulis immersorum._ Sweat from covering the face in bed. 3. _Cessatio ægritudinis cute_ Cure of sickness by stimulating _excitata._ the skin. 4. _Digestio aucta frigore cutaneo._ Digestion increased by coldness of the skin. 5. _Catarrhus a frigore cutaneo._ Catarrh from cold skin. 6. _Absorptio cellularis aucta_ Cellular absorption increased by _vomitu._ vomiting. 7. _Syngultus nephriticus._ Nephritic hiccough. 8. _Febris irritativa._ Irritative fever. GENUS II. _Catenated with Sensitive Motions._ SPECIES. 1. _Lacrymarum fluxus_ Sympathetic tears. _sympatheticus._ 2. _Sternutatio a lumine._ Sneezing from light. 3. _Dolor dentium a Stridore._ Tooth-edge from grating sounds. 4. _Risus sardonicus._ Sardonic smile. 5. _Salivæ fluxus cibo viso._ Flux of saliva at sight of food. 6. _Tensio mamularum viso puerulo._ Tension of the nipples of lactescent women at sight of the child. 7. _Tensio penis in hydrophobia._ Tension of the penis in hydrophobia. 8. _Tenesmus calculosus._ Tenesmus from stone. 9. _Polypus narium ex ascaride._ Polypus of the nose from ascarides. 10. _Crampus surarum in diarrhoea._ Cramp from diarrhoea. 11. _Zona ignea nephritica._ Nephritic shingles. 12. _Eruptio variolarum._ Eruption of small-pox. 13. _Gutta rosea stomatica._ Stomatic rosy drop. 14. ---- _hepatica._ Hepatic rosy drop. 15. _Podagra._ Gout. 16. _Rheumatismus._ Rheumatism. 17. _Erysipelas._ Erysipelas. 18. _Testium tumor in gonorrhoea._ Swelled testis in gonorrhoea. 19. ---- _in parotitide._ ---- in mumps. GENUS III. _Catenated with Voluntary Motions._ SPECIES. 1. _Deglutitio invita._ Involuntary deglutition. 2. _Nictitatio invita._ ---- nictitation. 3. _Risus invitus._ ---- laughter. 4. _Lusus digitorum invitus._ ---- actions with the fingers. 5. _Unguium morsiuncula invita._ ---- biting the nails. 6. _Vigilia invita._ ---- watchfulness. GENUS IV. _Catenated with External Influences._ SPECIES. 1. _Vita ovi._ Life of an egg. 2. _Vita hiemi-dormientium._ Life of winter-sleepers. 3. _Pullulatio arborum._ Budding of trees. 4. _Orgasmatis venerei periodus._ Periods of venereal desire. 5. _Brachii concussio electrica._ Electric shock through the arm. 6. _Oxygenatio sanguinis._ Oxygenation of the blood. 7. _Humectatio corporis._ Humectation of the body. ORDO II. _Decreased Associate Motions._ GENUS I. _Catenated with Irritative Motions._ SPECIES. 1. _Cutis frigida pransorum._ Chillness after dinner. 2. _Pallor urinæ pransorum._ Pale urine after dinner. 3. ---- _a frigore cutaneo._ ---- from cold skin. 4. _Pallor ex ægritudine._ Paleness from sickness. 5. _Dyspnoea a balneo frigido._ Shortness of breath from cold bathing. 6. _Dyspepsia a pedibus frigidis._ Indigestion from cold feet. 7. _Tussis a pedibus frigidis._ Cough from cold feet. 8. ---- _hepatica._ Liver-cough. 9. ---- _arthritica._ Gout-cough. 10. _Vertigo rotatoria._ Vertigo rotatory. 11. ---- _visualis._ ---- visual. 12. ---- _ebriosa._ ---- inebriate. 13. ---- _febriculosa._ ---- feverish. 14. ---- _cerebrosa._ ---- from the brain. 15. _Murmur aurium vertiginosum._ Noise in the ears. 16. _Tactus, gustus, olfactus_ Vertiginous touch, taste, smell. _vertiginosi._ 17. _Pulsus mollis a vomitione._ Soft pulse in vomiting. 18. ---- _intermittens a ventriculo._ Intermittent pulse from the stomach. 19. _Febris inirritativa._ Inirritative fever. GENUS II. _Catenated with Sensitive Motions._ SPECIES. 1. _Torpor genæ a dolore dentis._ Coldness of the cheek from tooth-ach. 2. _Stranguria a dolore vesicæ._ Strangury from pain of the bladder. 3. ---- _convulsiva._ Convulsive strangury. 4. _Dolor termini ductûs_ Pain of the end of the bile-duct. _choledochi._ 5. _Dolor pharyngis ab acido_ Pain of the throat from gastric acid. _gastrico._ 6. _Pruritus narium a vermibus._ Itching of the nose from worms. 7. _Cephalæa._ Head-ach. 8. _Hemicrania et otalgia._ Partial head-ach, and ear-ach. 9. _Dolor humeri in hepatitide._ Pain of shoulder in hepatitis. 10. _Torpor pedum variolâ_ Cold feet in eruption of small-pox. _erumpente._ 11. _Testium dolor nephriticus._ Nephritic pain of testis. 12. _Dolor digiti minimi_ Pain of little finger from sympathy. _sympatheticus._ 13. _Dolor brachii in hydrope_ Pain of the arm in dropsy of the _pectoris._ chest. 14. _Diarrhoea a dentitione._ Diarrhoea from toothing. GENUS III. _Catenated with Voluntary Motions._ SPECIES. 1. _Titubatio linguæ._ Impediment of speech. 2. _Chorea sancti viti._ St. Vitus' dance. 3. _Risus._ Laughter. 4. _Tremor ex irâ._ Trembling from anger. 5. _Rubor ex irâ._ Redness from anger. 6. ---- _criminati._ Blush of guilt. 7. _Tarditas paralytica._ Slowness from palsy. 8. ---- _senilis._ ---- of age. GENUS IV. _Catenated with External Influences._ SPECIES. 1. _Somni periodus._ Periods of sleep. 2. _Studii inanis periodus._ ---- of reverie. 3. _Hemicraniæ periodus._ ---- of head-ach. 4. _Epilepsiæ dolorificæ periodus._ ---- of painful epilepsy. 5. _Convulsionis dolorificæ periodus._ ---- of painful convulsion. 6. _Tussis periodicæ periodus._ ---- of periodic cough. 7. _Catameniæ periodus._ ---- of catamenia. 8. _Hæmorrhoidis periodus._ ---- of the piles. 9. _Podagræ periodus._ ---- of the gout. 10. _Erysipelatis periodus._ ---- of erysipelas. 11. _Febrium periodus._ ---- of fevers. ORDO III. _Retrograde Associate Motions._ GENUS I. _Catenated with Irritative Motions._ SPECIES. 1. _Diabætes irritata._ Diabetes from irritation. 2. _Sudor frigidus in asthmate._ Cold sweat in asthma. 3. _Diabætes a timore._ Diabetes from fear. 4. _Diarrhoea a timore._ Diarrhoea from fear. 5. _Pallor et tremor a timore._ Paleness and trembling from fear. 6. _Palpitatio cordis a timore._ Palpitation of the heart from fear. 7. _Abortio a timore._ Abortion from fear. 8. _Hysteria a timore._ Hysterics from fear. GENUS II. _Catenated with Sensitive Motions._ SPECIES. 1. _Nausea idealis._ Nausea from ideas. 2. ---- _a conceptu._ Nausea from conception. 3. _Vomitio vertiginosa._ Vomiting from vertigo. 4. ---- _a calculo in uretere._ ---- from stone in the ureter. 5. ---- _ab insultu paralytico._ ---- from stroke of palsy. 6. ---- _a titilatione faucium._ ---- from tickling the throat. 7. ---- _cute sympathetica._ ---- from sympathy with the skin. GENUS III. _Catenated with Voluntary Motions._ SPECIES. 1. _Ruminatio._ Rumination. 2. _Vomitio voluntaria._ Voluntary vomiting. 3. _Eructatio voluntaria._ ---- eructation. GENUS IV. _Catenated with External Influences._ SPECIES. 1. _Catarrhus periodicus._ Periodical catarrh. 2. _Tussis periodica._ Periodic cough. 3. _Histeria a frigore._ Hysterics from cold. 4. _Nausea pluvialis._ Sickness against rain. * * * * * CLASS IV. DISEASES OF ASSOCIATION. ORDO I. _Increased Associate Motions._ GENUS I. _Catenated with Irritative Motion._ The importance of the subsequent class not only consists in its elucidating all the sympathetic diseases, but in its opening _a road to the knowledge of fever_. The difficulty and novelty of the subject must plead in excuse for the present imperfect state of it. The reader is entreated previously to attend to the following circumstances for the greater facility of investigating their intricate connections; which I shall enumerate under the following heads. A. Associate motions distinguished from catenations. B. Associate motions of three kinds. C. Associations affected by external influences. D. Associations affected by other sensorial motions. E. Associations catenated with sensation. F. Direct and reverse sympathy. G. Associations affected four ways. H. Origin of associations. I. Of the action of vomiting. K. Tertian associations. A. _Associate Motions distinguished from Catenations._ Associate motions properly mean only those, which are caused by the sensorial power of association. Whence it appears, that those fibrous motions, which constitute the introductory link of an associate train of motions, are excluded from this definition, as not being themselves caused by the sensorial power of association, but by irritation, or sensation, or volition. I shall give for example the flushing of the face after dinner; the capillary vessels of the face increase their actions in consequence of their catenation, not their association, with those of the stomach; which latter are caused to act with greater energy by the irritation excited by the stimulus of food. These capillaries of the face are associated with each other reciprocally, as being all of them excited by the sensorial power of association; but they are only catenated with those of the stomach, which are not in this case associate motions but irritative ones. The common use of the word association for almost every kind of connection has rendered this subject difficult; from which inaccuracy I fear some parts of this work are not exempt. B. _Associate Motions of three Kinds._ Those trains or tribes of associate motions, whose introductory link consists of an irritative motion, are termed irritative associations; as when the muscles of the eyelids close the eye in common nictitation. Those, whose introductory link consists of a sensitive motion, are termed sensitive associations; as when the pectoral and intercostal muscles act in sneezing. And lastly, those, whose introductory link consists of a voluntary motion, are termed voluntary associations; as when the muscles of the lower limbs act in concert with those of the arm in fencing. C. _Associations affected by external Influences._ Circles of associate motions, as well as trains and tribes of them, are liable to be affected by external influences, which consist of etherial fluids, and which, by penetrating the system, act upon it perhaps rather as a causa sine quâ non of its movements, than directly as a stimulus; except when they are accumulated in unusual quantity. We have a sense adapted to the perception of the excess or defect of one of these fluids; I mean that of elementary heat; in which all things are immersed. See Class IV. 1. 4. 7. But there are others of them, which as we have no power to evade their influence, so we have no sense to perceive it; these are the solar, and lunar, and terrestrial gravitation, in which also all things are immersed; the electric aura, which pervades us, and is perpetually varying, See Class IV. 1. 4. 5; the magnetic fluid, Class IV. 1. 4. 5; and lastly, the great life-preserver oxygen gas, and the aqueous vapour of the atmosphere, see Class IV. 1. 4. 6. and 7. and 2. Of these external influences those of heat, and of gravity, have diurnal periods of increase and decrease; besides their greater periods of monthly or annual variation. The manner in which they act by periodical increments on the system, till some effect is produced, is spoken of in Sect. XXXII. 3. and 6. D. _Associations affected by other Sensorial Motions._ Circles and trains of associate motions are also liable to be affected by their catenations with other sensorial powers, as of irritation, or sensation, or volition; which other sensorial powers either thus simply form some of the links of the catenation, or add to the energy of the associated motions. Thus when vomiting is caused by the stimulus of a stone in the ureter, the sensation of pain seems to be a link of the catenation rather than an efficient cause of the vomiting. But when the capillary vessels of the skin increase their action from the influence of external heat, they are excited both by the stimulus of unusual heat, as well as by the stimulus of the blood, and by their accustomed association with the actions of the heart and arteries. And lastly, in the blush of anger the sensorial power of volition is added to that of association, and irritation, to excite the capillaries of the face with increased action. See Class IV. 2. 3. 5. E. _Associations catenated with Sensation._ Pain frequently accompanies associate trains or circles of motion without its being a cause, or a link, of them, but simply an attendant symptom; though it frequently gives name to the disease, as head-ach. Thus in the cramp of the calves of the legs in diarrhoea, the increased sensorial power of association is the proximate cause; the preceding increased action of the bowels is the remote cause; and the proximate effect is the violent contractions of the musculi gastrocnemii; but the pain of these muscles is only an attendant symptom, or a remote effect. See Sect. XVIII. 15. Other sensitive associations are mentioned in Class IV. 1. 2. and IV. 1. 2. 15. Thus, if the flushing of the face above mentioned after dinner be called a disease, the immediate or proximate cause is the increased power of association, the remote cause is the increased irritative motions of the stomach in consequence of the stimulus of food and wine. The disease or proximate effect consists in the increased actions of the cutaneous vessels of the face; and the sensation of heat, the existence of heat, and the red colour, are attendants or symptoms, or remote effects, of the increased actions of these cutaneous vessels. F. _Direct and reverse Sympathy._ The increased actions of the primary part of the trains of associated motions are sometimes succeeded by increased actions of the secondary part of the train; and sometimes by decreased actions of it. So likewise the decreased actions of the primary part of a train of associate motions are sometimes succeeded by decreased actions of the secondary part, and sometimes by increased actions of it. The former of these situations is called direct sympathy, and the latter reverse sympathy. In general I believe, where the primary part of the train of associated motions is exerted more than natural, it produces direct sympathy in strong people, and reverse sympathy in weak ones, as a full meal makes some people hot, and others chill. And where the primary part of the train is exerted less than natural, it produces direct sympathy in weak people, and reverse sympathy in strong ones, as on being exposed for a certain length of time on horseback in a cold day gives indigestion and consequent heart-burn to weak people, and strengthens the digestion, and induces consequent hunger in strong ones. See Sect. XXXV. 1. This may perhaps be more easily understood, by considering strength and weakness, when applied to animal bodies, as consisting in the quantity of sensorial power residing in the contracting fibres, and the quantity of stimulus applied, as shewn in Sect. XII. 2. 1. Now when defective stimulus, within certain limits, is partially applied to parts subject to perpetual motion, the expenditure of sensorial power is for a while lessened, but not its general production in the brain, nor its derivation into the weakly-stimulated part. Hence in strong people, or such whose fibres abound with sensorial power, if the first tribe of an associate train of motions be deprived in part of its accustomed stimulus, its action becomes diminished; and the sensorial power becomes accumulated, and by its superabundance, or overflowing as it were, increases the action of the second tribe of the associate actions by reverse sympathy. As exposing the warm skin for a moderate time to cold air increases the action of the stomach, and thus strengthens the power of digestion. On the reverse, when additional stimulus within certain limits is partially applied to parts, which are deficient in respect to the natural quantity of sensorial power, the expenditure of sensorial power is increased, but in a less degree than the increased production of it in the brain, or its increased derivation into the strongly-stimulated organ. Hence in weak people, or such whose fibres are deficient of sensorial power, if the first tribe of an associate train of motions be subjected for a while to greater stimulus than usual, a greater production of sensorial power, or a greater derivation of it into the stimulated parts occurs; which by its excess, or overflowing as it were, increases the actions of the second tribe of the associate motions by direct sympathy. Thus when vomiting occurs with cold extremities, a blister on the back in a few hours occasions universal warmth of the skin, and stops the vomiting. And when a diarrhoea occurs with pale skin and cold extremities, the pricking of the points of a flannel shirt, worn next the skin, occasions universal warmth of it, and checks or cures the diarrhoea. In some associate trains of action nevertheless reverse sympathies more frequently occur than direct ones, and in others direct ones more frequently than reverse ones. Thus in continued fever with debility there appears to be a reverse sympathy between the capillary vessels of the stomach and those of the skin; because there exists a total aversion to solid food, and constant heat on the surface of the body. Yet these two systems of vessels are at other times actuated by direct sympathy, as when paleness attends sickness, or cold feet induces indigestion. This subject requires to be further investigated, as it probably depends not only on the present or previous plus or minus of the sensorial power of association, but also on the introduction of other kinds of sensorial power, as in Class IV. 1. 1. D; or the increased production of it in the brain, or the greater mobility of one part of a train of actions than another. Thus when much food or wine is taken into the stomach, if there be no superfluity of sensorial power in the system, that is, none to be spared from the continual actions of it, a paleness and chillness succeeds for a time; because now the expenditure of it by the increased actions of the stomach is greater than the present production of it. In a little time however the stimulus of the food and wine increases the production of sensorial power in the brain, and this produces a superfluity of it in the system; in consequence of which the skin now becomes warm and florid, which was at first cold and pale; and thus the reverse sympathy is shortly converted into a direct one; which is probably owing to the introduction of a second sensorial power, that of pleasurable sensation. On the contrary, when an emetic drug produces sickness, the skin is at first pale for a time by direct sympathy with the capillaries of the stomach; but in a few minutes, by the accumulation of sensorial power in the stomach during its less active state in sickness, the capillaries of the skin, which are associated with those of the stomach, act with greater energy by reverse sympathy, and a florid colour returns. Where the quantity of action is diminished in the first part of a train of motions, whether by previous diminution of sensorial power, or present diminution of stimulus, the second part of the train becomes torpid by direct sympathy. And when the quantity of action of the first part becomes increased by the accumulation of sensorial power during its previous torpor, or by increase of stimulus, the actions of the second part of it likewise become increased by direct sympathy. In moderate hunger the skin is pale, as before dinner, and in moderate sickness, as no great accumulation of sensorial power has commenced; but in violent hunger, and in greater torpor of the stomach, as from contagious matter, the accumulation of sensorial power becomes so great as to affect the arterial and capillary system, and fever is produced in both cases. In contagious fevers with arterial debilities commencing with torpor of the stomach, why is the action of the heart weakened, and that of the capillaries increased? Is it because the mobility of the heart is less than that of the stomach, and the mobility of the capillaries greater? Or is it because the association between the muscular fibres of the stomach and those of the heart have been uniformly associated by direct sympathy; and the capillaries of the stomach and those of the skin have been more frequently associated by reverse sympathy? Where the actions of the stomach have been previously exhausted by long stimulus, as on the day after intoxication, little or no accumulation of sensorial power occurs, during the torpor of the organ, beyond what is required to replace the deficiency of it, and hence fever seldom follows intoxication. And a repetition of the stimulus sometimes becomes necessary even to induce its natural action, as in dram-drinkers. Where there has been no previous exhaustion of sensorial power, and the primary link of associate motions is violently actuated by the sensorial power of sensation, the secondary link is also violently actuated by direct sympathy, as in inflammatory fevers. Where however the sensorial power of the system is less than natural, the secondary link of associated motions becomes torpid by reverse sympathy, as in the inoculated small-pox during the eruption on the face the feet are frequently cold. G. _Associations affected four Ways._ Hence associated trains or circles of motions may be affected four different ways. 1. By the greater or less energy of action of the first link with which they are catenated, and from which they take their names; as irritative, sensitive, or voluntary associations. 2. By being excited by two or more sensorial powers at the same time, as by irritation and association, as in the instance of the application of the stimulus of increased external heat to the cutaneous capillaries. 3. By catenation with other sensorial powers, as with pain or pleasure, which are in this case not the proximate cause of motion, but which, by becoming a link of catenation, excites the sensorial power of association into action; as the pain at the neck of the gall-bladder occasioned by a gall-stone is transferred to the other end of that canal, and becomes a link of catenation between the action of the two extremities of it. 4. The influence of ethereal fluids, as of heat and gravitation. To which last perhaps might be added moisture and oxygen gas as constituting necessary parts of the system, rather than stimuli to excite it into action. H. _The Origin of Associations._ Some trains or circles of associate motions must have been formed before our nativity, as those of the heart, arteries, and capillaries; others have been associated, as occasion required them, as the muscles of the diaphragm and abdomen in vomiting; and others by perpetual habit, as those of the stomach with the heart and arteries directly, as in weak pulse during sickness; with the capillaries directly, as in the flushed skin after dinner; and lastly, with the cellular absorbents reversely, as in the increased absorption in anasarca during sickness; and with the irritative motions of the organs of sense reversely, as in vertigo, or sea-sickness. Some of these associations shall be here shortly described to facilitate the investigation of others. First, other congeries of glands occupy but a particular part of the system, or constitute a particular organ, as the liver, or kidneys; but those glands, which secrete the mucus, and perspirable matter, which are called capillaries, are of very great extent; they receive the blood from the arteries, separate from it the mucus, which lines every cell, and covers every cavity of body; and the perspirable matter, which softens and lubricates the whole surface of the skin, and the more extensive surface of the air-vessels, which compose the lungs. These are supplied with blood by the perpetual action of the heart and arteries, and have therefore their motions associated with the former, and with each other, by sympathy, which is sometimes direct, and sometimes reverse. One branch of this association, the capillaries of the skin, are very irritable by the increased quantities of cold and heat, another branch, that of the lungs, has not the perception of cold and heat, but is liable by direct sympathy to act in concert with the former, as in going into the cold bath. And it is probable the capillaries of the internal membranes are likewise directly affected by their sympathy with those of the skin, as appears from the defect of secretion in ulcers during the cold fits of agues. The motions of this extensive system of capillaries, thus associated by direct sympathy, are also associated with those of the heart and arteries, sometimes by reverse and sometimes by direct sympathy; and thus constitute simple fever. The cold paroxysm of which consists in their torpor, and the hot one in their orgasm, or increased activity. I. _Of the Action of Vomiting._ The manner, in which the stomach and the diaphragm and abdominal muscles acquire their associate action in vomiting, requires some attention. It is not probable, that this action of vomiting occurs before nativity; as the uniform application of the nutritive liquor amnii to the mouth of the foetus, and the uniform expenditure of its nourishment, would not seem to give occasion to too great temporary repletion of the stomach; and would preclude the deglutition of any improper material. After nativity the stomach of the child may be occasionally too much distended with milk; as previous hunger may induce it to overgorge itself; and by repeated efforts the act of vomiting is learned, as a means of getting free from a disagreeable sensation. Thus when any disgustful material, as a bitter drug, is taken into the mouth; certain retrograde motions of the tongue and lips are produced, for the purpose of putting the disagreeable material out of the mouth again. When the stomach is disagreeably stimulated by the distention or acrimony of the aliment, a similar effort to regurgitate it must occur; and by repeated trials the action of the diaphragm and abdominal muscles by squeezing the stomach assists its retrograde exertion to disgorge its contents. In the same manner when a piece of gravel is pushed into the urethra, or a piece of indurated bile into the neck of the gall-bladder, after they have been in vain pressed forward by the usual motions of those ducts, they return into the bladders of gall and urine by the retrograde motions of them. That this is one mode, in which vomiting is induced, appears from the instantaneous rejection from the stomach occasioned by some nauseous drug, or from some nauseous idea; and lastly, from the voluntary power, which some people have been said to have acquired, of emptying their stomachs, much in the same manner as ruminating animals bring up the grass from their first stomach. There are nevertheless many modes by which these inverted motions of the stomach and oesophagus are induced, and which it is of consequence to distinguish from each other. The first is the mode above described, where an effort is made to dislodge something, which stimulates the stomach into disagreeable sensation; and which is returned by repeated exertions; as when a nauseous drug is taken into the mouth, or a bit of sand falls into the eye, or a drop of water into the wind-pipe. In this the peristaltic motions of the stomach are first stopped, and then reverted by painful sensation; and the abdominal muscles and diaphragm by repeated efforts become associated with them. Now as less sensorial power is expended on the retrograde actions of the stomach, and of the lymphatics, which open their mouths on its surface, than by their natural motions, an accumulation of sensorial power in the fibres of the stomach follows the exhibition of an emetic, and on that account an emetic will sometimes stop a spontaneous vomiting which was owing to sensorial deficiency. See Sect. XXXV. 1. 3. and Art. V. 2. 1. As bitters and metallic salts, exhibited in small doses, stimulate the stomach into greater action, as appears by their increasing the power of digestion, and yet become emetic, when given in larger doses; one might suspect, that they became emetic by inducing debility, and consequent retrograde actions of the stomach, by their previously exhausting the sensorial power by their great stimulus; which might be effected in a moment without producing pain, and in consequence without our perceiving it. But on the contrary, there does not in general appear on the exhibition of emetics to be any previous exhaustion of sensorial power; because there is evidently an accumulation of it during the sickness, as appears from the digestion being stronger afterwards; and from the increased action of the cellular and cutaneous absorbents during its operation. See Art. V. 2. 1. Another mode, by which vomiting is induced, is owing to debility or deficiency of sensorial power, from the previous exhaustion of it; as on the day after intoxication, or which occurs in people enfeebled with the gout, and in dropsy, and in some fevers with debility. In these, when the vomiting ceases, there is no appearance of accumulation of sensorial power, as the digestion still remains weak and imperfect. Another mode by which sickness or vomiting is induced, is by defect of stimulus, as in great hunger; and in those, who have been habituated to spice and spirit with their meals, who are liable to be sick after taking food without these additional stimuli. Other means of inducing sickness by vertigo, or by nauseous ideas, will be mentioned below. We shall only add, that the motions of the muscular fibres of the stomach are associated with those of the heart and arteries by direct sympathy, as appears by the weakness of the pulse during the exhibition of an emetic; and that the absorbents of the stomach are associated with the cellular and cutaneous absorbents by reverse sympathy, as is shewn by the great absorption of the mucus of the cells in anasarca during sickness; at the same time that the absorbents of the stomach invert their actions, and pour the mucus and water thus absorbed into that viscus. In cold paroxysms of fever the stomach partakes of the general torpor, and vomiting is induced by its debility, either by its association with the torpid capillaries, or other torpid parts, or by its own torpor commencing first, and causing the cold fit. The disordered motions of the stomach frequently seem to be the cause or primary seat of fever, as where contagious miasmata are swallowed with the saliva, and where fever is produced by sea-sickness, which I once saw. Nevertheless a disorder of the stomach does not always induce fever, as in that case it should constantly attend indigestion, and vertigo, and sea-sickness; but is itself frequently induced by association with the disordered movements of other parts of the system, as when it arises from gravel in the ureter, or from a percussion on the head. The connexion of the motions of the stomach with irritative ideas, or motions of the organs of sense, in vertigo, is shewn in Sect. XX. and thus it appears, that many circles of association are either directly or reversely associated, or catenated, with this viscus; which will much contribute to unfold some of the symptoms of fever. K. _Tertian Associations._ The third link of associate trains of motion is sometimes actuated by reverse sympathy, with the second link, and that by reverse sympathy with the first link; so that the first and third link may act by direct sympathy, and the intermediate one by reverse sympathy. Of this instances are given in the syngultus nephriticus, Class IV. 1. 1. 7. and IV. 2. 1. At other times the tertian or quartan links of associate motions are actuated by direct sympathy; and that sometimes forwards and sometimes backwards in respect to the usual order of those trains of associate motions, as in Class IV. 1. 2. 1. SPECIES. 1. _Rubor vultûs prandorum._ Flushing of the face after dinner is explained in Sect. XXXV. 1. In the beginning of intoxication the whole skin becomes florid from the association of the actions of the cutaneous arteries with those of the stomach, because vinous spirit excites the fibres of the stomach into more violent action than the stimulus of common food; and the cutaneous capillaries of the face, from their more frequent exposure to the vicissitudes of cold and heat, possess more mobility or irritability than those of other parts of the skin, as further explained in Sect. XXXIII. 2. 10. Vinegar is liable to produce this flushing of the face, which probably is owing to the quantity of vinous spirit it contains, as I believe the unfermented vegetable acids do not produce this effect. In every kind of blush the arterial blood is propelled into the capillaries faster than the venous absorption can carry it forwards into the veins, in this respect resembling the tensio phalli. Can the beginning vinous or acetous fermentation of the aliment in weak stomachs contribute to this effect? or is it to be ascribed to the greater power of association between the arteries of the face and the fibres of the stomach in some people than in others? M. M. Eat and drink less at a time, and more frequently. Put 20 drops of weak acid of vitriol into water to be drank at meals. Let the dress over the stomach and bowels be loose. Use no fermented liquors, or vinegar, or spice. 2. _Sudor stragulis immersorum._ Sweat from being covered in bed. In the commencement of an epidemic fever, in which the perpetual efforts to vomit was a distressing symptom, Dr. Sydenham discovered, that if the patient's head was for a short time covered over with the bed clothes, warmth was produced, and a sweat broke out upon the skin, and the tendency to vomit ceased. In this curious fact two trains of associated motions are excited into increased action. First, the vessels of the lungs are known to have their motion associated with those of the skin by the difficulty of breathing on going into the cold bath, as described in Sect. XXXII. 3. 2. Hence, when the vessels of the lungs become excited into stronger action, by the bad air under the bed clothes, warmed and adulterated by frequent breathing, those of the external skin soon become excited by their association into more energetic action, and generate more heat along with a greater secretion of perspirable matter. Secondly, the sympathy between the stomach and skin is evident in variety of circumstances; thus the cold air of frosty days applied to the skin for a short time increases the action of the stomach by reverse sympathy, but decreases it if continued too long by direct sympathy; so in the circumstance above mentioned the action of the stomach is increased by direct sympathy with that of the skin; and the tendency to vomit, which was owing to its diminished action, ceases. 3. _Cessatio ægritudinis cute excitatâ._ The cure of sickness by stimulating the skin. This is explained in the preceding article; and further noticed in IV. 2. 2. 4. and in IV. 1. 1. f. Similar to these is the effect of a blister on the back in relieving sickness, indigestion, and heart-burn; and, on the contrary, by these symptoms being frequently induced by coldness of the extremities. The blister stimulates the cutaneous vessels into greater action; whence warmth and pain are produced at the same time, and the fibres of the stomach are excited into greater action by their association with those of the skin. It does not appear, that the concomitant pain of the blister causes the increased energy of the stomach, because the motions of it are not greater than natural; though it is sometimes difficult to determine, whether the primary part of some associated trains be connected with irritative or sensitive motions. In the same manner a flannel shirt, to one who has not been in the habit of wearing one, stimulates the skin by its points, and thus stops vomiting in some cases; and is particularly efficacious in checking some chronical diarrhoeas, which are not attended with fever; for the absorbents of the skin are thus stimulated into greater action, with which those of the intestines consent by direct sympathy. This effect cannot be ascribed to the warmth alone of the flannel shirt, as being a covering of loose texture, and confining air in its pores, like a sponge, which air is known to be a bad conductor of heat, since in that case its use should be equally efficacious, if it were worn over a linen shirt; and an increased warmth of the room of the patient would be equally serviceable. 4. _Digestio aucta frigore cutaneo._ Digestion increased by coldness of the skin. Every one has experienced the increase of his appetite after walking in the cool air in frosty days; for there is at this time not only a saving of sensorial power by the less exertion of the cutaneous vessels; but, as these consent with those of the stomach and bowels, this saving of sensorial power is transferred by reverse sympathy from the cutaneous capillaries and absorbents to those of the stomach and intestines. Hence weak people should use the cold air of winter as a cold bath; that is, they should stay in it but a short time at once, but should immerse themselves in it many times a day. 5. _Catarrhus a frigore cutaneo._ Catarrh from cold skin. This has been already explained in Class I. 1. 2. 7. and is further described in Sect. XXXV. 1. 3. In this disease the vessels of the membrane, which lines the nostrils, are excited into greater action; when those of the skin, with which they are associated, are excited into less action by the deficiency of external heat, by reverse sympathy; and though the pain of cold attends the torpor of the primary link of this association, yet the increased motions of the membrane of the nostrils are associated with those of the cutaneous vessels, and not with the pain of them, because no inflammation follows. 6. _Absorptio cellularis aucta vomitu._ In the act of vomiting the irritative motions of the stomach are inverted, and of the absorbents, which open their mouths into it; while the cutaneous, cellular, and pulmonary absorbents are induced, by reverse sympathy with them, to act with greater energy. This is seen in cases of anasarca, when long sickness and vomiting are caused by squills, or antimonial salts, or most of all by the decoction of digitalis purpurea, foxglove; and Mr. J. Hunter mentions a case, in which a large bubo, which was just ready to break, was absorbed in a few days by sickness at sea. Treatise on the Blood, p. 501, which is thus accounted for; less sensorial power is expended during sickness by the decreased action of the fibres of the stomach, and of its absorbents; as shewn in Sect. XXXV. 1. 3. whence an accumulation of it is produced, and there is in consequence a greater quantity of sensorial power for the exertion of those motions, which are associated with the absorbents of the stomach by reverse sympathy. The reverse sympathy between the lacteal and lymphatic branches of the absorbent system have been produced by the one branch being less excited to act, when the other supplies sufficient fluid or nutriment to the sanguiferous vessels. Thus when the stomach is full, and the supply of chyle and mucus and water is in sufficient quantity; the pulmonary, cellular, and cutaneous lymphatics are not excited into action; whence the urine is pale, and the skin moist, from the defect of absorption on those surfaces. 7. _Syngultus nephriticus._ When a stone irritates the ureter, and that even without its being attended with pain or fever, sometimes a chronical hiccough occurs, and continues for days and weeks, instead of sickness or vomiting; which are the common symptoms. In this case the motions of the stomach are decreased by their sympathy with those of the ureter, which are increased by the stimulus of the stone in it; and the increased motions of the diaphragm seem to exist in consequence of their association with the stomach by a second reverse sympathy. This hiccough may nevertheless admit of another explanation, and be supposed to be a convulsive exertion of the diaphragm to relieve the disagreeable sensation of the stomach in consequence of its disordered irritative associations; and in that case it would belong to Class III. 1. 1. See Class IV. 2. 1. for another example of tertiary association. M. M. Venesection. Emetic. Calomel. Cathartic, opium, oil of cinnamon from two to ten drops. Aerated alcaline water. Peruvian bark. 8. _Febris irritativa._ Irritative fever, described in Class I. 1. 1. 1. The diseases above explained in this genus are chiefly concerning the sympathies of the absorbent system, or the alimentary canal, which are not so much associated with the arterial system, as to throw it into disorder, when they are slightly deranged; but when any great congeries of conglomerate glands, which may be considered as the extremities of the arterial system, are affected with torpor, the whole arterial system and the heart sympathize with the torpid glands, and act with less energy; which constitutes the cold fit of fever; which is therefore at first a decreased action of the associate organ; but as this decrease of action is only a temporary effect, and an increase of exertion both of the torpid glands, and of the whole arterial system, soon follows; the hot fit of irritative fever, or fever with strong pulse, properly belongs to this class and genus of diseases. * * * * * ORDO I. _Increased Associate Motions._ GENUS II. _Catenated with Sensitive Motions._ The primary links of the associated actions of this genus are either produced or attended by painful or pleasurable sensation. The secondary links of the first ten species are attended with increased motions without inflammation, those of the remainder are attended with inflammation. All inflammations, which do not arise in the part which was previously torpid, belong to this genus; as the gout, rheumatism, erysipelas. It is probable many other inflammations may, by future observation, require to be transplanted into this class. The circles of sensitive associate motions consist chiefly of the excretory ducts of the capillaries and of the mouths of the absorbent vessels, which constitute the membranes; and which have been induced into action at the same time; or they consist of the terminations of canals; or of parts which are endued with greater sensibility than those which form the first link of the association. An instance of the first of those is the sympathy between the membranes of the alveolar processes of the jaws, and the membranes above or beneath the muscles about the temples in hemicrania. An instance of the second is in the sympathy between the excretory duct of the lacrymal gland, and the nasal duct of the lacrymal sack. And an instance of the third is the sympathy between the membranes of the liver, and the skin of the face in the gutta rosea of inebriates. SPECIES. 1. _Lacrymarum fluxus sympatheticus._ A flow of tears from grief or joy. When the termination of the duct of the lacrymal sac in the nostrils becomes affected either by painful or pleasurable sensations, in consequence of external stimulus, or by its association with agreeable or disagreeable ideas, the motions of the lacrymal gland are at the same time exerted with greater energy, and a profusion of tears succeeds by sensitive association, as explained in Sect. XVI. 8. 2. In this case there exists a chain of associated actions, the secretion of the lacrymal gland is increased by whatever stimulates the surface of the eye, at the same time the increased abundance of tears stimulates the puncta lacrymalia into greater action; and the fluid thus absorbed stimulates the lacrymal sac, and its nasal duct in the nose into greater action. In a contrary direction of this chain of association the present increase of action is induced. First, the nasal duct of the lacrymal sac is excited into increased action by some pleasurable or painful idea, as described in Sect. XVI. 8. 2. 2d. The puncta lacrymalia or other extremity of the lacrymal sac sympathizes with it (as the two ends of all other canals sympathize with each other). 3d. With these increased motions of the puncta lacrymalia those of the excretory duct of the lacrymal gland are associated from their having so perpetually acted together. And, lastly, with the increased actions of the excretory duct of this gland are associated those of the other end of it by their frequently acting together; in the same manner as the extremities of other canals are associated; and thus a greater flow of tears is poured into the eye. When a flow of tears is produced in grief, it is believed to relieve the violence of it, which is worthy a further inquiry. Painful sensations, when great, excite the faculty of volition; and the person continues voluntarily to call up or perform those ideas, which occasion the painful sensation; that is, the afflicted person becomes so far insane or melancholy; but tears are produced by the sensorial faculty of association, and shew that the pain is so far relieved as not to excite the excessive power of volition, or insanity, and are therefore a sign of the abatement of the painful state of grief, rather than a cause of that abatement. See Class III. 1. 2. 10. 2. _Sternutatio a lumine._ Some persons sneeze from looking up at the light sky in a morning after coming out of a dark bedroom. The olfactory nerves are brought into too great action by their sympathy with the optic nerves, or by their respective sympathies with some intervening parts, as probably with the two extremities of the lacrymal sac; that is, with the puncta lacrymalia and the nasal duct. See Class II. 1. 1. 3. 3. _Dolor dentium Stridore._ Tooth-edge from grating sounds, and from the touch of certain substances, and even from imagination alone, is described and explained in Sect. XVI. 10. The increased actions of the alveolar vessels or membranes are associated with the ideas, or sensual motions of the auditory nerves in the first case; and of those of the sense of touch, in the second case; and by imagination, or ideas exerted of painful sensation alone, in the last. 4. _Risus sardonicus._ A disagreeable smile attends inflammations of the diaphragm arising from the associations of the reiterated exertions of that muscle with those of the lips and cheeks in laughing. See Diaphragmitis, Class II. 1. 2. 6. 5. _Salivæ fluxus cibo viso._ The flow of saliva into the mouths of hungry animals at the sight or smell of food is seen in dogs standing round a dinner-table. The increased actions of the salivary glands have been usually produced by the stimulus of agreeable food on their excretory ducts during the mastication of it; and with this increased action of their excretory ducts the other terminations of those glands in the capillary arteries have been excited into increased action by the mutual association of the ends of canals; and at the same time the pleasurable ideas, or sensual motions, of the sense of smell and of sight have accompanied this increased secretion of saliva. Hence this chain of motions becomes associated with those visual or olfactory ideas, or with the pleasure, which produces or attends them. 6. _Tensio mamularum viso puerulo._ The nipples of lactescent women are liable to become turgid at the sight of their young offspring. The nipple has generally been rendered turgid by the titillation of the lips or gums of the child in giving suck; the visible idea of the child has thus frequently accompanied this pleasurable sensation of parting with the milk, and turgescence of the tubes, which constitute the nipple. Hence the visual idea of the child, and the pleasure which attends it, become associated with those increased arterial actions, which swell the cells of the mamula, and extend its tubes; which is very similar to the tensio phalli visâ muliere nudâ etiam in insomnio. 7. _Tensio penis in hydrophobia._ An erection of the penis occurs in the hydrophobia, and is a troublesome symptom, as observed by Coelius Aurelianus, Fothergill, and Vaughn, and would seem to be produced by an unexplained sympathy between the sensations about the fauces and the penis. In men the hair grows about both these parts, the voice changes, and the neck thickens at puberty. In the mumps, when the swellings about the throat subsides, the testicles are liable to swell. Venereal infection received by the penis is very liable to affect the throat with ulcers. Violent coughs, with soreness or rawness about the fauces are often attended with erection of the penis; which is also said to happen to male animals, that are hanged; which last circumstance has generally been ascribed to the obstruction of the circulation of the blood, but is more probably occasioned by the stimulus of the cord in compressing the throat; since if it was owing to impeded circulation it ought equally to occur in drowning animals. In men the throat becomes so thickened at the time of puberty, that a measure of this is used to ascertain the payment of a poll-tax on males in some of the islands of the Mediterranean, which commences at puberty; a string is wrapped twice round the thinnest part of the neck, the ends of it are then put into each corner of the mouth; and if, when thus held in the teeth, it passes readily over the head, the subject is taxable. It is difficult to point out by what circumstance the sensitive motions of the penis and of the throat and nose become associated; I can only observe, that these parts are subjected to greater pleasurable sensations than any other parts of the body; one being designed to preserve ourselves by the pleasure attending the smell and deglutition of food, and the other to ensure the propagation of our species; and may thus gain an association of their sensitive motion by their being eminently sensible to pleasure. See Class I. 3. 1. 11. and III. 1. 1. 15. and Sect. XVI. 5. In the female sex this association between the face, throat, nose, and pubis does not exist; whence no hair grows on their chins at the time of puberty, nor does their voices change, or their necks thicken. This happens probably from there being in them a more exquisite sensitive sympathy between the pubis and the breasts. Hence their breasts swell at the time of puberty, and secrete milk at the time of parturition. And in the parotitis, or mumps, the breasts of women swell, when the tumor of the parotitis subsides. See Class I. 1. 2. 15. Whence it would appear, that their breasts possess an intermediate sympathy between the pubis and the throat; as they are the seat of a passion, which men do not possess, that of suckling children. 8. _Tenesmus calculosus._ The sphincter of the rectum becomes painful or inflamed from the association of its sensitive motions with those of the sphincter of the bladder, when the latter is stimulated into violent pain or inflammation by a stone. 9. _Polypus narium ex ascaridibus?_ The stimulation of ascarides in the rectum produces by sensitive sympathy an itching of the nose, as explained in IV. 2. 2. 6; and in three children I have seen a polypus in the nose, who were all affected with ascarides; to the perpetual stimulation of which, and the consequent sensitive association, I was led to ascribe the inflammation and thickening of the membrane of the nostrils. 10. _Crampus surarum in cholera._ A cramp of the muscles of the legs occurs in violent diarrhoea, or cholera, and from the use of too much acid diet in gouty habits. This seems to sympathize with uneasy sensation in the bowels. See Class III. 1. 1. 14. This association is not easily accounted for, but is analogous in some degree to the paralysis of the muscles of the arms in colica saturnina. It would seem, that the muscles of the legs in walking get a sympathy with the lower parts of the intestines, and those of the arms in variety of employment obtain a sympathy with the higher parts of them. See Cholera and Ileus. 11. _Zona ignea nephritica._ Nephritic shingles. The external skin about the loins and sides of the belly I suppose to have greater mobility in respect to sensitive association, than the external membrane of the kidney; and that their motions are by some unknown means thus associated. When the torpor or beginning inflammation of this membrane ceases, the external skin becomes inflamed, in its stead, and a kind of herpes, called the shingles, covers the loins and sides of the belly. See Class II. 1. 5. 9. 12. _Eruptio variolarum._ After the inflammation of the inoculated arm has spread for a quarter of a lunation, it affects the stomach by reverse sympathy; that is, the actions of the stomach are associated with those of the skin; and as much sensorial power is now exerted on the inflamed skin, the other part of this sensitive association is deprived of its natural share, and becomes torpid, or inverts its motions. After this torpor of the stomach has continued a time, and much sensorial power is thus accumulated; other parts of the skin, which are also associated with it, as that of the face first, are thrown into partial inflammation; that is, the eruptions of the small-pox appear on the face. For that the variolous matter affects the stomach previous to its eruption on the skin appears from the sickness at the commencement of the fever; and because, when the morbid motions affect the skin, those of the stomach cease; as in the gout and erysipelas, mentioned below. The consent between the stomach and the skin appears in variety of other diseases; and as they both consist of surfaces, which absorb and secrete a quantity of moisture, their motions must frequently be produced together or in succession; which is the foundation of all the sympathies of animal motions, whether of the irritative, sensitive, or voluntary kinds. Now as the skin, which covers the face, is exposed to greater variations of heat and cold than any other part of the body; it probably possesses more mobility to sensitive associations, not only than the stomach, but than any other part of the skin; and is thence affected at the eruption of the small-pox with violent action and consequent inflammation, by the association of its motions with those of the stomach, a day before the other parts of the skin; and becomes fuller of pustules, than any other part of the body. See Class II. 1. 3. 9. It might be supposed, that the successive swelling of the hands, when the face subsides, at the height of the small-pox, and of the feet, when the hands subside, were governed by some unknown associations of those parts of the system; but these successions of tumor and subsidence more evidently depend on the times of the eruption of the pustules on those parts, as they appear a day sooner on the face than on the hands, and a day sooner on the hands than on the feet, owing to the greater comparative mobility of those parts of the skin. 13. _Gutta rosea stomatica._ Stomatic red face. On drinking cold water, or cold milk, when heated with exercise, or on eating cold vegetables, as raw turnips, many people in harvest-time have been afflicted with what has been called a surfeit. The stomach becomes painful, with indigestion and flatulency, and after a few days an eruption of the face appears, and continues with some relief, but not with entire relief; as both the pimpled face and indigestion are liable to continue even to old age. M. M. Venesection. A cathartic with calomel. Then half a grain of opium twice a day for many weeks. If saturated solution of arsenic three or five drops twice or thrice a day for a week? 14. _Gutta rosea hepatica._ The rosy drop of the face of some drinking people is produced like the gout described below, in consequence of an inflamed liver. In these constitutions the skin of the face being exposed to greater variation of heat and cold than the membranes of the liver, possesses more mobility than those hepatic membranes; and hence by whatever means these membranes are induced to sympathize, when this sensitive association occurs, the cutaneous vessels of the face run into greater degrees of those motions, which constitute inflammation, than previously existed in the membranes of the liver; and then those motions of the liver cease. See Class II. 1. 4. 6. An inflammation of the liver so frequently attends the great potation of vinous spirit, there is reason to suspect, that this viscus itself becomes inflamed by sensitive association with the stomach; or that, when one termination of the bile-duct, which enters the duodenum is stimulated violently, the other end may become inflamed by sensitive association. 15. _Podagra._ The gout, except when it affects the liver or stomach, seems always to be a secondary disease, and, like the rheumatism and erysipelas mentioned below, begins with the torpor of some distant part of the system. The most frequent primary seat of the gout I suppose to be the liver, which is probably affected with torpor not only previous to the annual paroxysms of the gout, but to every change of its situation from one limb to another. The reasons, which induce me to suspect the liver to be first affected, are not only because the jaundice sometimes attends the commencement of gout, as described in Sect. XXIV. 2. 8. but a pain also over the pit of the stomach, which I suppose to be of the termination of the bile-duct in the duodenum, and which is erroneously supposed to be the gout of the stomach, with indigestion and flatulency, generally attends the commencement of the inflammation of each limb. See Arthritis ventriculi, Class I. 2. 4. 6. In the two cases, which I saw, of the gout in the limbs being preceded by jaundice, there was a cold shivering fit attended the inflammation of the foot, and a pain at the pit of the stomach; which ceased along with the jaundice, as soon as the foot became inflamed. This led me to suspect, that there was a torpor of the liver, and perhaps of the foot also, but nevertheless the liver might also in this case be previously inflamed, as observed in Sect. XXIV. 2. 8. Now as the membranes of the joints of the feet suffer greater variations of heat and cold than the membranes of the liver, and are more habituated to extension and contraction than other parts of the skin in their vicinity; I suppose them to be more mobile, that is, more liable to run into extremes of exertion or quiescence; and are thence more susceptible of inflammation, than such parts as are less exposed to great variations of heat and cold, or of extension and contraction. When a stone presses into the sphincter of the bladder, the glans penis is affected with greater pain by sympathy, owing to its greater sensibility, than the sphincter of the bladder; and when this pain commences, that of the sphincter ceases, when the stone is not too large, or pushed too far into the urethra. Thus when the membrane, which covers the ball of the great toe, sympathizes with some membranous part of a torpid or inflamed liver; this membrane of the toe falls into that kind of action, whether of torpor or inflammation, with greater energy, than those actions excited in the diseased liver; and when this new torpor or inflammation commences, that with which it sympathises ceases; which I believe to be a general law of associated inflammations. The paroxysms of the gout would seem to be catenated with solar influence, both in respect to their larger annual periods, and to their diurnal periods--See Sect. XXXVI. 3. 6.--as the former occur about the same season of the year, and the latter commence about an hour before sun-rise; nevertheless the annual periods may depend on the succession of great vicissitudes of cold and heat, and the diurnal ones on our increased sensibility to internal sensations during sleep, as in the fits of asthma, and of some epilepsies. See Sect. XVIII. 15. In respect to the pre-remote cause or disposition to the gout, there can be no doubt of its individually arising from the potation of fermented or spirituous liquors in this country; whether opium produces the same effect in the countries, where it is in daily use, I have never been well informed. See Sect. XXI. 10, where this subject is treated of; to which I have to add, that I have seen some, and heard of others, who have moderated their paroxysms of gout, by diminishing the quantity of fermented liquors, which they had been accustomed to; and others who, by a total abstinence from fermented liquors, have entirely freed themselves from this excruciating malady; which otherwise grows with our years, and curtails or renders miserable the latter half, or third, of the lives of those, who are subject to it. The remote cause is whatever induces temporary torpor or weakness of the system; and the proximate cause is the inirritability, or defective irritation, of some part of the system; whence torpor and consequent inflammation. The great Sydenham saw the beneficial effects of the abstinence from fermented liquors in preventing the gout, and adds, "if an empiric could give small-beer only to gouty patients as a nostrum, and persuade them not to drink any other spirituous fluids, that he might rescue thousands from this disease, and acquire a fortune for his ingenuity." Yet it is to be lamented, that this accurate observer of diseases had not resolution to practise his own prescription, and thus to have set an example to the world of the truth of his doctrine; but, on the contrary, recommends Madeira, the strongest wine in common use, to be taken in the fits of the gout, to the detriment of thousands; and is said himself to have perished a martyr to the disease, which he knew how to subdue! As example has more forcible effect: than simple assertion, I shall now concisely relate my own case, and that of one of my most respected friends. E. D. was about forty years of age, when he was first seized with a fit of the gout. The ball of his right great toe was very painful, and much swelled and inflamed, which continued five or six days in spite of venesection, a brisk cathartic with ten grains of calomel, and the application of cold air and cold water to his foot. He then ceased to drink ale or wine alone; confining himself to small beer, or wine diluted with about thrice its quantity of water. In about a year he suffered two other fits of the gout, in less violent degree. He then totally abstained from all fermented liquors, not even tasting small-beer, or a drop of any kind of wine; but eat plentifully of flesh-meat, and all kinds of vegetables, and fruit, using for his drink at meals chiefly water alone, or lemonade, or cream and water; with tea and coffee between them as usual. By this abstinence from fermented liquors he kept quite free from the gout for fifteen or sixteen years; and then began to take small-beer mixed with water occasionally, or wine and water, or perry and water, or cyder and water; by which indulgence after a few months he had again a paroxysm of gout, which continued about three days in the ball of his toe; which occasioned him to return to his habit of drinking water, and has now for above twenty years kept in perpetual health, except accidental colds from the changes of the seasons. Before he abstained from fermented or spirituous liquors, he was frequently subject to the piles, and to the gravel, neither of which he has since experienced. In the following case the gout was established by longer habit and greater violence, and therefore required more cautious treatment. The Rev. R. W. was seized with the gout about the age of thirty-two, which increased so rapidly that at the age of forty-one he was confined to his room seven months in that year; he had some degree of lameness during the intervals, with chalky swellings of his heels and elbows. As the disease had continued so long and so violently, and the powers of his digestion were somewhat weakened, he was advised not entirely to leave off all fermented liquors; and as small-beer is of such various strength, he was advised to drink exactly two wine glasses, about four ounces, of wine mixed with three or four times its quantity of water, with or without lemon and sugar, for his daily potation at dinner, and no other fermented liquor of any kind; and was advised to eat flesh-meat with any kind of boiled vegetables, and fruit, with or without spice. He has now scrupulously continued this regimen for above five years, and has had an annual moderate gouty paroxysm of a few weeks, instead of the confinement of so many months, with great health and good spirits during the intervals. The following is a more particular account of the history of this case; being part of a letter which Mr. Wilmot wrote on that subject at my entreaty. "I entered into the army with an excellent constitution at the age of fifteen. The corps I served in was distinguished by its regularity, that is, the regular allowance of the mess was only one pint of wine per man each day; unless we had company to dine with us; then, as was the general custom of the time, the bottle circulated without limit. This mode of living, though by no means considered as excess for men, was certainly too great for a youth of my age. This style of living I continued, when with the regiment, till the latter end of the year 1769, when I had the misfortune to sleep in a damp bed at Sheffield on a journey to York, but arrived there before I felt the ill effects of it. I was then seized with a violent inflammatory rheumatism with great inflammation of my eyes, and was attended by Dr. Dealtry; so violent was the disorder, that I was bled for it eight times in less than a fortnight; and was three months, before I could consider my health perfectly re-established. Dr. Dealtry told me, that I should be subject to similar attacks for many years; and that he had no doubt, from the tendency he found in my habit to inflammation, that, when I was farther advanced in life, I should change that complaint for the gout. He predicted truly; for the three succeeding winters I had the same complaint, but not so violently; the fourth winter I escaped, and imputed my escape to the continuance of cold bathing during the whole of that winter; after that I never escaped it, till I had a regular and severe fit of the gout: after the first attack of rheumatic fever I was more abstemious in my manner of living, though when in company I never subjected myself to any great restraint. In the year 1774 I had quitted the army, and being in a more retired situation, was seldom led into any excess; in 1776 and 1777 I was in the habit of drinking a good deal of wine very frequently, though not constantly. After that period till the year 1781, I drank a larger quantity of wine regularly, but very seldom to any degree of intoxication. I lived much at that time in the society of some gentlemen, who usually drank nearly a bottle of wine daily after dinner. I must here however observe, that at no part of my life was I accustomed to drink wine in an evening, and very seldom drank any thing more than a single half-pint glass of some sort of spirits diluted with much water. Till the year 1781 I had always been accustomed to use very violent and continued exercise on horseback; in the winter months I pursued all field diversions, and in the summer months I rode frequent and long journeys; and with this exercise was liable to perspire to great excess; besides which I was subject to very profuse night-sweats, and had frequently boils break out all over me, especially in the spring and autumn; for which I took no medicine, except a little flour of sulphur with cream of tartar in honey. "You will observe I bring every thing down to the date of 1781. In the month of October in that year, when I was just entered into the thirty-second year of my age, I had the first attack of gout; that fit was very severe, and of many weeks continuance. I now determined upon a more abstemious method of living, in respect to wine; and indeed the society, in which I had before been accustomed to live, being considerably changed, I had less frequent temptations to excess. From this time I enjoyed the most perfect good state of health till August 1784, when I had my second attack of gout. I never perfectly recovered from this attack through the succeeding winter, and in March 1785 was advised to try the Bath waters, and drank them under the direction of one of the faculty of that place. I was there soon seized with a fever, and a slight attack of gout in one knee. I should observe, that when I set out from home, I was in a weak and low state, and unequal to much fatigue; as appeared by my having a fainting fit one day on the road, after having travelled only about fifty miles; in the course of the summer I had two or three more slight attacks of gout of less consequence, till the month of October; when I was afflicted with it all over me in such a manner, as to be without the possibility of the least degree of removal for some days; and was about two months without being able to get into the air. This was the severest attack I had then experienced; though I have since had several equally severe. In the course of this summer I had a fall with my horse; and soon after it, having discovered an enlargement on one elbow, I concluded I had hurt it at that time; but in the course of this last attack having a similar enlargement on the other elbow, I found my mistake, and that they were collections of gouty matter; these increased to the size of pullet's eggs, and continue in that state. I had soon after similar enlargements on my heels; the right heel being severely bruised, I was under the necessity of having it lanced, and a large quantity of chalky matter was discharged from it; and have since that time frequently had chalky matter taken from it, and sometimes small bits of apparently perfect chalk. My right hand soon was afflicted in the same way, and I have scarcely a joint on those fingers now in a natural state. My left hand has escaped tolerably well. After this last attack (viz. October 1785), I had two or three slight attacks before the month of June 1787, when I had a very severe intermittent fever; from that time I continued very well till the latter end of the year, when I began to feel the gout about me very much, but was not confined by it. I was in this state advised to try what is called the American Recipe (gum guaiacum and nitre dissolved in spirits); it had apparently been of essential service to a friend of mine, who from the inability to walk a mile for some years, was believed to be restored by the use of this medicine to a good state of health, so as to walk ten miles a day. In addition to this medicine I drank, as my common beverage with my meals, spruce beer. I had so high an opinion of this medicine in the gout, and of spruce beer as an antiscorbutic, that I contemplated with much satisfaction, and with very little doubt, the perfect restoration of my health and strength; but I was miserably deceived; for in September 1788 I was seized with the gout in a degree that none but arthritics, and indeed but few of those, can easily conceive. From this time till August 1789 I scarcely ever passed a comfortable day; seven months of this time I had been confined, my health seemed much impaired, my strength was diminished, and my appetite almost gone. In this state my friends pressed me to consult you. I was unwilling for some time to do it, as I had lost all hope of relief; however, when I had determined to apply to you, I likewise determined to give up every prejudice of my own respecting my case, and to adhere most strictly to your advice. On the 20th of August 1789 I consulted you, on the 25th I entered upon the regimen, which you prescribed, and which was as follows. "Drink no malt liquor on any account. Let your beverage at dinner consist of two glasses of wine diluted with three half-pints of water. On no account drink any more wine or spirituous liquors in the course of the day; but, if you want more liquid, take cream and water, or milk and water, or lemonade, with tea, coffee, chocolate. Use the warm bath twice a week for half an hour before going to bed, at the degree of heat which is most grateful to your sensations. Eat meat constantly at dinner, and with it any kind of tender vegetables you please. Keep the body open by two evacuations daily, if possible without medicine, if not take the size of a nutmeg of lenitive electuary occasionally, or five grains of rhubarb every night. Use no violent exercise, which may subject yourself to sudden changes from heat to cold; but as much moderate exercise as may be, without being much fatigued or starved with cold. Take some supper every night; a small quantity of animal food is preferred; but if your palate refuses this, take vegetable food, as fruit pie, or milk; something should be eaten, as it might be injurious to you to fast too long." To the whole of this I adhered most scrupulously, and soon found my appetite improve, and with it my strength and spirits. I had in December a fevere attack, and two or three slight ones in the course of twelve months; but the improvement in the general state of my health induced me to persevere. On the 18th of August 1790 I had another severe attack, but it went off easier than before, and I soon recovered sufficiently to go to Buxton, which you advised me to, and from which I reaped great benefit; nevertheless on the 29th of December I had a slight attack in comparison of some that I had before experienced, and from that time I was free from gout, and enjoyed my health perfectly well till the fourth week in October 1791; from that till the third week in October 1792; from that till the third week in October 1793; and from that till June 1794. From what happened for the last three years I dreaded the month of October; but I escaped then, and have enjoyed my health most perfectly ever since till within the last week, that I have had a slight attack in one knee, which is nearly gone, without any symptom to lead me to suppose that it will go further. "I adhered to your advice most scrupulously for the first year; and in regard to the not drinking malt liquor, and taking only the two glasses of wine with water, I have never deviated but two days; and then the first day I only drank one glass of ale and one glass of Champaigne; on the second only one glass of Champaigne. With regard to the warm bath, I only use it now when I have gouty symptoms upon me, and in such situations I find it of infinite service; and in other respects I continue to live according to your direction. "Many persons have laughed at the idea of my perseverance in a system, which has not been able to _cure_ the gout after five years trial; but such persons are either ignorant of what I before suffered, or totally unacquainted with the nature of the disorder. Under the blessing of Providence, by an adherence to your advice, I am reaping all the benefit you flattered me I might expect from it, viz. my attacks less frequent, my sufferings less acute, and an improvement in the general state of my health. "I have been particular in this account of myself at your request, and am, Sir, &c. MORLEY, near DERBY, February 10th, 1795. ROBERT WILMOT." There are situations nevertheless in which a paroxysm of gout has been believed to be desirable, as relieving the patient from other disagreeable diseases, or debilities, or sensations. Thus when the liver is torpid, a perpetual uneasiness and depression of spirits occur; which a fit of gout is supposed to cure by a metastasis of the disease. Others have acquired epileptic fits, probably from the disagreeable sensation of a chronically inflamed liver; which they suppose the pain and inflammation of gout would relieve. When gouty patients become much debilitated by the progress of the disease, they are liable to dropsy of the chest, which they suppose a fit of the gout would relieve. But in all these cases the attempt to procure a paroxysm of gout by wine, or aromatics, or volatiles, or blisters, or mineral waters, seldom succeeds; and the patients are obliged to apply to other methods of relief adapted to their particular cases. In the two former situations small repeated doses of calomel, or mercurial unction on the region of the liver may succeed, by giving new activity to the vessels of the liver, either to secrete or to absorb their adapted fluids, and thus to remove the cause of the gout, rather than to promote a fit of it. In the last case the tincture of digitalis, and afterwards the class of sorbentia, must be applied to. M. M. In young strong patients the gout should be cured by venesection and cathartics and diluents, with poultices externally. But it has a natural crisis by producing calcareous matter on the inflamed membrane, and therefore in old enfeebled people it is safest to wait for this crisis, attending to the natural evacuations and the degree of fever; and in young ones, where it is not attended with much fever, it is customary and popular not to bleed, but only to keep the body open with aloes, to use gentle sudorifics, as neutral salts, and to give the bark at the decline of the fit; which is particularly useful where the patient is much debilitated. See Arthritis ventriculi, Class I. 2. 4. 6. and Sect. XXV. 17. When there is not much fever, and the patient is debilitated with age, or the continuance of the disease, a moderate opiate, as twenty drops of tincture of opium, or one grain of solid opium, may be taken every night with advantage. Externally a paste made with double the quantity of yeast is a good poultice; and booterkins made with oiled silk, as they confine the perspirable matter, keep the part moist and supple, and thence relieve the pain like poultices. The only safe way of moderating the disease is by an uniform and equal diminution, or a total abstinence from fermented liquors, with the cautions directed in Sect. XII. 7. 8. The continued use of strong bitters, as of Portland's powder, or bark, has been frequently injurious, as spoken of in the Materia Medica, Art. IV. 2. 11. One of my acquaintance, who was much afflicted with the gout, abstained for about half a year from beer and wine; and not having resolution to persist, returned to his former habits of potation in less quantity; and observed that he was then for one winter stronger and freer from the gout than usual. This however did not long continue, as the disease afterwards returned with its usual or increased violence. This I think is a circumstance not unlikely to occur, as opium has a greater effect after its use has been a while intermitted; and the debility or torpor, which is the cause of gout, is thus for a few months prevented by the greater irritability of the system, acquired during the lessened use of fermented liquor. For the same reason an ounce of spirituous tincture of guaiacum, or of bark, is said to have for some time prevented returns of the gout; which has afterwards, like all other great stimuli when long continued, been succeeded by greater debility, and destroyed the patient. This seems to have been exemplified in the case of the ingenious Dr. Bown, see Preface to his Elementa Medicinæ; he found temporary relief from the stimulus of wine, regardless of its future effects. 16. _Rheumatismus._ Acute rheumatism. There is reason to suspect, that rheumatic inflammations, like the gouty ones, are not a primary disease; but that they are the consequence of a translation of morbid action from one part of the system to another. This idea is countenanced by the frequent change of place of rheumatic-like gouty inflammations, and from their attacking two similar parts at the same time, as both ankles and both wrists, and these attacks being in succession to each other. Whereas it is not probable that both feet or both hands should at the same time be equally exposed to any external cause of the disease, as to cold or moisture; and less so that these should occur in succession. Lastly, from the inflammatory diathesis in this disease being more difficult to subdue, and more dangerous in event, than other common inflammations, especially to pregnant women, and in weak constitutions. From this idea of the rheumatism being not a primary disease, like the gout, but a transferred morbid action owing to the previous torpor of some other part of the system, we perceive why it attacks weak people with greater pertinacity than strong ones; resisting or recurring again and again after frequent evacuations, in a manner very different from primary inflammations; because the cause is not removed, which is at a distance from the seat of the inflammation. This also accounts for rheumatic inflammations so very rarely terminating in suppuration, because like the gout the original cause is not in the inflamed part, and therefore does not continue to act after the inflammation commences. Instead of suppuration in this disease, as well as in the gout, a quantity of mucus or coagulable lymph is formed on the inflamed membrane; which in the gout changes into chalkstones, and in the rheumatism is either reabsorbed, or lies on the membrane, producing pains on motion long after the termination of the inflammation, which pains are called chronic rheumatism. The membranes, which have thus been once or repeatedly inflamed, become less mobile, or less liable to be affected by sympathy, as appears by the gout affecting new parts, when the joints of the foot have been frequently inflamed by it; hence as the cause of the inflammation does not exist in the inflamed part, and as this part becomes less liable to future attacks, it seldom suppurates. Secondly, when rheumatism affects the muscles of the chest, it produces symptoms similar to pleurisy, but are distinguished from that by the patient having previously suffered rheumatic affections in other parts, and by the pertinacity or continuance of the inflammatory state of the patient, this should be termed pleurodyne rheumatica. Thirdly, when rheumatic inflammation affects the bowels, it produces a disease very different from enteritis, or common inflammation of the bowels, and should be termed enteralgia rheumatica. The pain is less than in enteritis, and the disease of longer continuance, with harder pulse, and the blood equally sizy. It is attended with frequent dejections, with much mucus, and previous griping pains, but without vomiting; and differs perhaps from dysentery from its not being attended with bloody stools, and not being infectious. Fourthly, there is another kind of rheumatism attended with debility, which suppurates, and should be termed rheumatismus suppurans. It is generally believed to be the gout, till suppuration takes place on the swelled joint; and, as the patient sinks, there are sloughs formed over the whole mouth; and he seems to be destroyed by inflammation or gangrene of the mucous membranes. I have twice seen this disease in patients about sixty. Some other diseases are erroneously called rheumatic, as hemicrania, and odontalgia. See Sect. XXVI. 3. M.M. In the three former kinds venesection repeatedly. Cathartics. Antimonials. Diluents. Neutral salts. Oil. Warm bath. Afterwards the bark. Opium with or without ipecacuanha; but not till the patient is considerably weakened. Sweats forced early in the disease do injury. Opium given early in the disease prolongs it. In the last kind, gentle stimulants, as wine and water, mucilage, sorbentia. The following is a case of suppurative rheumatism. Mr. F----, about sixty, was supposed to have the gout in his hand, which however suppurated, and it was then called the suppurative rheumatism. He had lived rather intemperately in respect to wine, and was now afflicted with a tendency to inflammation of the mucous membranes. As he lay on the bed half resupine, propped up with pillows, and also slept in that posture, his lower jaw dropped by its own weight, when the voluntary power of the muscles was suspended. The mucus of his mouth and throat became quite dry, and at length was succeeded with sloughs; this was a most distressing circumstance to him, and was in vain endeavoured to be relieved by supporting his jaw by slender steel springs fixed to his night-cap, and by springs of elastic gum. The sloughs spread and seemed to accelerate his death. See Class I. 1. 3. 2. 17. _Erysipelas._ The erysipelas differs from the zona ignea, and other species of herpes, in its being attended with fever, which is sometimes of the sensitive irritated or inflammatory kind, with strong and full pulse; and at other times with weak pulse and great inirritability, as when it precedes or attends mortifications. See Class II. 1. 3. 2. Like the zona ignea above described, it seems to be a secondary disease, having for its primary part the torpor or inflammation of some internal or distant membrane, as appears from its so frequently attending wounds; sometimes spreading from issues over the whole limb, or back, by sympathy with a tendon or membrane, which is stimulated by the pease in them. In its more violent degree I suppose that it sympathizes with some extensive internal membranes, as of the liver, stomach, or brain. Another reason, which countenances this idea, is, that the inflammation gradually changes its situation, one part healing as another inflames; as happens in respect to more distant parts in gout and rheumatism; and which seems to shew, that the cause of the disease is not in the same place with the inflammation. And thirdly, because the erysipelas of the face and head is liable to affect the membranes of the brain; which were probably in these cases the original or primary seat of the disease; and lastly, because the fits of erysipelas, like those of the gout, are liable to return at certain annual or monthly periods, as further treated of in Class II. 1. 3. 2. Many cases of erysipelas from wounds or bruises are related in Default's Surgical Journal, Vol. II. in which poultices are said to do great injury, as well as oily or fatty applications. Saturnine solutions were sometimes used with advantage. A grain of emetic tartar given to clear the stomach and bowels, is said to be of great service. 18. _Testium tumor in gonorrhoea._ Mr. Hunter in his Treatise on the Venereal Disease observes, that the tumor of the testes in gonorrhoea arises from their sympathy with the inflammation of the urethra; and that they are not similar to the actions arising from the application of venereal matter, whether by absorption or otherwise; as they seldom or never suppurate; and when suppuration happens, the matter produced is not venereal. Treatise on Venereal Disease, p. 53. 19. _Testium tumor in parotidite._ The sympathy between some parts about the throat and the genitals has been treated of in Class IV. 1. 2. 7. The swelling of the testes, when that of the parotis subsides, seems to arise from the association of successive action; as the tension of the penis in hydrophobia appears to arise from the previous synchronous associations of the sensitive motions of these parts; but the manner of the production of both these associations is yet very obscure. In women a swelling of the breasts often succeeds the decline of the mumps by another wonderful sympathy. See Class IV. 1. 2. 7. and I. 1. 2. 15. In many persons a delirium succeeds the swelling of the parotis, or the subsequent ones of the testes or breasts; which is sometimes fatal, and seems to arise from a sympathy of successive action, and not of synchronous action, of the membranes of the brain with those of the parotide glands. Sometimes a stupor comes on instead of this delirium, which is relieved by fomenting the shaved head for an hour or two. See Class II. 1. 3. 4. * * * * * ORDO I. _Increased Associate Motions._ GENUS III. _Catenated with Voluntary Motions_ SPECIES. 1. _Deglutitio invita._ When any one is told not to swallow his saliva, and that especially if his throat be a little sore, he finds a necessity of immediately swallowing it; and this the more certainly, the more he voluntarily endeavours not to do so. In this case the voluntary power exerted by our attention to the pharinx renders it more sensible to irritation, and therefore occasions it to be more frequently induced to swallow the saliva. Here the irritation induces a volition to swallow it, which is more powerful than the desire not to swallow it. See XXIV. 1. 7. So in reverie, when the voluntary power was exerted on any of the senses, as of sight or taste, the objects of those senses became perceived; but not otherwise. Sect. XIX. 6. This is a troublesome symptom in some sore throats. M. M. Mucilage, as sugar and gum arabic. Warm water held in the mouth frequently, as a fomentation to the inflamed throat. 2. _Nictitatio invita._ Involuntary winking with the eye-lids, and twitchings of the face, are originally induced by an endeavour to relieve some disagreeable sensations about inflamed eyes, as the dazzling of light; and afterwards these motions become catenated with other motions or sensations, so as not to be governed by the will. Here the irritation first produces a volition to wink, which by habit becomes stronger than the anti-volition not to wink. This subject is rendered difficult from the common acceptation of the word, volition, including previous deliberation, as well as the voluntary exertion, which succeeds it. In the volitions here spoken of there is no time for deliberation or choice of objects, but the voluntary act immediately succeeds the sensation which excites it. M. M. Cover the affected parts with a sticking plaster or a blister. Pass a fine needle and thread through a part of the skin over the muscle, which moves, and attach the other end of the thread by a sticking plaster to a distant part. An issue behind the ear. To practise daily by a looking-glass to stop the motions with the hand. See the cure of a case of the leaping of a muscle of the arm, Sect. XVII. 1. 8. See Convulsio debilis, Class III. 1. 1. 5. 3. _Risus invitus._ Involuntary laughter. When the pleasure arising from new combinations of words and ideas, as in puns; or of other circumstances, which are so trivial, as to induce no voluntary exertion to compare or consider their present importance or their future consequence; the pleasure is liable to rise into pain; that is, the ideas or sensual motions become exerted too violently for want of some antithetistic ideas; in the same manner as those muscles, which have weak antagonists, as those of the calf of the leg, are liable to fall into cramp or painful contraction. In this situation a scream is begun to relieve this pain of ideas too violently exerted, which is stopped again soon, as explained in Sect. XXXIV. 1. 4. and Class III. 1. 1. 4. and IV. 2. 3. 3. The pain, into which this pleasure rises, which would excite the scream of laughter, has been felt forcibly by every one; when they have been under such circumstances, as have induced them to restrain it by a counter-volition; till at length the increased associate motions produce so much pain as to overcome the counter-volition, and the patient bursts out into indecent laughter, contrary to his will in the common acceptation of that word. 4. _Lusus digitorum invitus._ An awkward playing with the fingers in speaking in public. These habits are began through bashfulness, and seem rather at first designed to engage the attention in part, and thus prevent the disagreeable ideas of mauvaise hont; as timorous boys whistle, when they are obliged to walk in the dark; and as it is sometimes necessary to employ raw soldiers in perpetual manoeuvres, as they advance to the first charge. 5. _Unguium morsiuncula invita._ Biting the nails is a depraved habit arising from similar causes as those of the last article. M. M. Dip the fingers in solution of aloes. 6. _Vigilia invita._ Watchfulness, where the person wishes, and endeavours to fall asleep, properly belongs to this place, as the wish or volition to sleep prevents the desired effect; because sleep consists in an abolition of volition. See Class III. 1. 2. 3. * * * * * ORDO I. _Increased Associate Motions._ GENUS IV. _Catenated with External Influences._ SPECIES. 1. _Vita ovi._ Life of an egg. The eggs of fowls were shewn by Mr. J. Hunter to resist the freezing process in their living state more powerfully, than when they were killed by having the yolk and white shook together. Philos. Trans. It may be asked, does the heat during the incubation of eggs act as a stimulus exciting the living principle into activity? Or does it act simply as a causa sine quâ non, as an influence, which penetrating the mass, removes the particles of it to a greater distance from each other, so as to allow their movement over each other, in the same manner as heat is conceived to produce the fluidity of water; not by stimulus, but by its penetrating influence? Or may elementary heat in its uncombined state be supposed to act only as an influence necessary to life in its natural quantity; whence torpor and death follows the eduction of it from the body; but in its increased state above what is natural, or usual, that it acts as a stimulus; which we have a sense to perceive; and which excites many parts of the system into unnatural action? See Class IV. 1. 1. C. 2. _Vita hiemi-dormientium._ The torpor of insects, and birds, and quadrupeds, during the cold season, has been called sleep; but I suppose it must differ very much from that state of animal life, since not only all voluntary power is suspended, but sensation and vascular motion has ceased, and can only be restored by the influence of heat. There have been related instances of snails, which have recovered life and motion on being put into water after having experienced many years of torpidity, or apparent death, in the cabinets of the curious. Here the water as well as the heat are required not only as a stimulus, but as a causa sine quâ non of fluidity and motion, and consequent life. 3. _Pullulatio arborum._ The annual revivescence of the buds of trees seems not only to be owing to the influence of the returning warmth of the spring, but also to be catenated with solar gravitation; because seeds and roots and buds, which are analogous to the eggs of animals, put forth their shoots by a less quantity of heat in spring, than they had undergone in the latter part of autumn, which may however be ascribed to their previous torpid state, and consequent accumulation of sensorial power, or irritability; as explained in Botanic Garden, Part II. Cant. I. l. 322. note. Other circumstances, which countenance the idea, that vegetation is affected by solar gravitation, as well as by heat, may be observed in the ripening of the seeds of plants both in those countries where the summers are short, and in those where they are long. And by some flowers closing their bells at noon, or soon after; and hence seem to sleep rather at solar diurnal periods, than from the influence of cold, or the deficiency of light. 4. _Orgasmatis venerei periodus._ The venereal orgasm of birds and quadrupeds commences or returns about the vernal or autumnal equinoxes, and thence seems in respect to their great periods to be governed by solar influence. But if this orgasm be disappointed of its object, it is said to recur at about monthly periods, as observed in mares and bitches in this respect resembling the female catamenia. See Sect. XXXVI. 2. 3. and Sect. XVI. 13. 5. _Brachii concussio electrica._ The movement of the arm, even of a paralytic patient, when an electric shock is passed through it, is owing to the stimulus of the excess of electricity. When a piece of zinc and silver, each about the size of a crown-piece, are placed one under the upper lip, and the other on the tongue, so as the outer edges may be brought into contact, there is an appearance of light in the eyes, as often as the outer edges of these metals are brought into contact or separated; which is another instance of the stimulus of the passage of electric shocks through the fibres of the organs of sense, as well as through the muscular fibres. See Sect. XII. 1. 1. and first addit. note to Vol. I. of this work. But in its natural state electricity seems only to act as an influence on animal and vegetable bodies; of the salutary or injurious effects of which we have yet no precise knowledge. Yet if regular journals were kept of the variations of atmospheric electricity, it is probable some discoveries of its influence on our system might in time be discovered. For this purpose a machine on the principle of Mr. Bennet's electric doubler might be applied to the pendulum of a clock, so as to manifest, and even to record the daily or hourly variations of aerial electricity. Which has already been executed, and applied to the pendulum of a Dutch wooden clock, by Mr. Bennet, curate of Wirksworth in Derbyshire. Besides the variations of the degree or kind of atmospheric electricity, some animals, and some men, seem to possess a greater power of accumulating this fluid in themselves than others. Of which a famous history of a Russian prince was lately published; who, during the clear and severe frosts of that country, could not move himself in bed without luminous corruscations. Such may have been the case of those people, who have been related to have taken fire spontaneously, and to have been reduced to ashes. The electric concussion from the gymnotus electricus, and torpedo, are other instances of the power of the animal system to accumulate electricity, as in these it is used as a weapon of defence, or for the purpose of taking their prey. Some have believed that the accumulation or passage of the magnetic fluid might affect the animal system, and have asserted that the application of a large magnet to an aching tooth has quickly effected a cure. If this experiment is again tried in odontalgia, or hemicrania, the painful membrane of the tooth or head should be included between the south and north poles of a horse-shoe magnet, or between the contrary poles of two different magnets, that the magnetism may be accumulated on the torpid part. 6. _Oxygenatio sanguinis._ The variation of the quantity of oxygen gas existing in the atmosphere must affect all breathing animals; in its excess this too must be esteemed a stimulus; but in its natural quantity would seem to act as an influence, or cause, without which, animal life cannot exist even a minute. It is hoped that Dr. Beddoes's plan for a pneumatic infirmary, for the purpose of putting this and various other airs to the test of experiment, will meet with public encouragement, and render consumption, asthma, cancer, and many diseases conquerable, which at present prey with unremitted devastation on all orders and ages of mankind. 7. _Humectatio corporis._ Water, and probably the vapour of water dissolved or diffused in the atmosphere, unites by mechanical attraction with the unorganized cuticle, and softens and enlarges it; as may be seen in the loose and wrinkled skin of the hands of washerwomen; the same probably occurs to the mucous membrane of the lungs in moist weather; and by thickening it increases the difficulty of respiration of some people, who are said to be asthmatical. So far water may be said to act as an influx or influence, but when it is taken up by the mouths of the absorbent system, it must excite those mouths into action, and then acts as a stimulus. There appears from hence to be four methods by which animal bodies are penetrated by external things. 1. By their stimulus, which induces the absorbent vessels to imbibe them. 2. By mechanical attraction, as when water softens the cuticle. 3. By chemical attraction, as when oxygen passes through the membranes of the air-vessels of the lungs, and combines with the blood. And lastly, by influx without mechanical attraction, chemical combination, or animal absorption, as the universal fluids of heat, gravitation, electricity, magnetism, and perhaps of other ethereal fluids yet unknown. * * * * * ORDO II. _Decreased Associate Motions._ GENUS I. _Catenated with Irritative Motions._ As irritative muscular motions are attended with pain, when they are exerted too weakly, as well as when they are exerted too strongly; so irritative ideas become attended with sensation, when they are exerted too weakly, as well as when they are exerted too strongly. Which accounts for these ideas being attended with sensation in the various kinds of vertigo described below. There is great difficulty in tracing the immediate cause of the deficiences of action of some links of the associations of irritative motions; first, because the trains and tribes of motions, which compose these links, are so widely extended as to embrace almost the whole animal system; and secondly, because when the first link of an associated train of actions is exerted with too great energy, the second link by reverse sympathy may be affected with torpor. And then this second link may transmit, as it were, this torpor to a third link, and at the same time regain its own energy of action; and it is possible this third link may in like manner transmit its torpor to a fourth, and thus regain its own natural quantity of motion. I shall endeavour to explain this by an example taken from sensitive associated motions, as the origin of their disturbed actions is more easily detected. This morning I saw an elderly person, who had gradually lost all the teeth in his upper jaw, and all of the under except three of the molares; the last of these was now loose, and occasionally painful; the fangs of which were almost naked, the gums being much wasted both within and without the jaw. He is a man of attentive observation, and assured me, that he had again and again noticed, that, when a pain commenced in the membranes of the alveolar process of the upper jaw opposite to the loose tooth in the under one (which had frequently occurred for several days past), the pain of the loose tooth ceased. And that, when the pain afterwards extended to the ear and temple on that side, the pain in the membranes of the upper jaw ceased. In this case the membranes of the alveolar process of the upper jaw became torpid, and consequently painful, by their reverse sympathy with the too violent actions of the inflamed membranes of the loose tooth; and then by a secondary sympathy the membranes about the ear and temple became torpid, and painful; and those of the alveolar process of the upper jaw regained their natural quantity of action, and ceased to be painful. A great many more nice and attentive observations are wanted to elucidate these curious circumstances of association, which will be found to be of the greatest importance in the cure of many diseases, and lead us to the knowledge of fever. SPECIES. 1. _Cutis frigida pransorum._ Chillness after dinner frequently attends weak people, or those who have been exhausted by exercise; it arises from the great expenditure of the sensorial power on the organs of digestion, which are stimulated into violent action by the aliment; and the vessels of the skin, which are associated with them, become in some measure torpid by reverse sympathy; and a consequent chillness succeeds with less absorption of atmospheric moisture. See the subsequent article. 2. _Pallor urinæ pransorum._ The paleness of urine after a full meal is an instance of reverse association; where the secondary part of a train of associate motions acts with less energy in consequence of the greater exertions of the primary part. After dinner the absorbent vessels of the stomach and intestines are stimulated into greater action, and drink up the newly taken aliment; while those, which are spread in great number on the neck of the bladder, absorb less of the aqueous part of the urine than usual, which is therefore discharged in a more dilute state; and has been termed crude by some medical writers, but it only indicates, that so great a proportion of the sensorial power is expended on digestion and absorption of the aliment, that other parts of the system act for a time with less energy. See Class IV. I. 1. 6. 3. _Pallor urinæ a frigore cutaneo._ There is a temporary discharge of pale water, and a diarrhoea, induced by exposing the skin to the cold air; as is experienced by boys, who strip themselves before bathing. In this case the mouths of the cutaneous lymphatics become torpid by the subduction of their accustomed degree of heat, and those of the bladder and intestines become torpid by direct sympathy; whence less of the thinner part of the urinary secretion, and of the mucus of the intestines, is reabsorbed. See Sect. XXIX. 4. 6. This effect of suddenly cooling the skin by the aspersion of cold water has been used with success in costiveness, and has produced evacuations, when other means have failed. When young infants are afflicted with griping joined with costiveness, I have sometimes directed them to be taken out of a warm bed, and carried about for a few minutes in a cool room, with almost instant relief. 4. _Pallor ex ægritudine._ When sickness of stomach first occurs, a paleness of the skin attends it; which is owing to the association or catenation between the capillaries of the stomach and the cutaneous ones; which at first act by direct sympathy. But in a short time there commences an accumulation of the sensorial power of association in the cutaneous capillaries during their state of inactivity, and then the skin begins to glow, and sweats break out, from the increased action of the cutaneous glands or capillaries, which is now in reverse sympathy with those of the stomach. So in continued fevers, when the stomach is totally torpid, which is known by the total aversion to solid food, the cutaneous capillaries are by reverse sympathy in a perpetual state of increased activity, as appears from the heat of the skin. 5. _Dyspnoea a balneo frigido._ The difficulty of breathing on going up to the middle in cold water is owing to the irritative association or catenation of the action of the extreme vessels of the lungs with those of the skin. So that when the latter are rendered torpid or inactive by the application of sudden cold, the former become inactive at the same time, and retard the circulation of the blood through the lungs, for this difficulty of breathing cannot be owing to the pressure of the water impeding the circulation downwards, as it happens equally by a cold shower-bath, and is soon conquered by habitual immersions. The capillaries of the skin are rendered torpid by the subduction of the stimulus of heat, and by the consequent diminution of the sensorial power of irritation. The capillaries of the lungs are rendered torpid by the diminution of the sensorial power of association, which is now excited in less quantity by the lessened actions of the capillaries of the skin, with which they are catenated. So that at this time both the cutaneous and pulmonary capillaries are principally actuated, as far as they have any action, by the stimulus of the blood. But in a short time the sensorial powers of irritation, and of association, become accumulated, and very energetic action of both these membranes succeed. Which thus resemble the cold and hot fit of an intermittent fever. 6. _Dyspepsia a pedibus frigidis._ When the feet are long cold, as in riding in cold and wet weather, some people are very liable to indigestion and consequent heart-burn. The irritative motions of the stomach become torpid, and do their office of digestion imperfectly, in consequence of their association with the torpid motions of the vessels of the extremities. Fear, as it produces paleness and torpidity of the skin, frequently occasions temporary indigestion in consequence of this association of the vessels of the skin with those of the stomach; as riding in very bad roads will give flatulency and indigestion to timorous people. A short exposure to cold air increases digestion, which is then owing to the reverse sympathy between the capillary vessels of the skin, and of the stomach. Hence when the body is exposed to cold air, within certain limits of time and quantity of cold, a reverse sympathy of the stomach and the skin first occurs, and afterwards a direct sympathy. In the former case the expenditure of sensorial power by the skin being lessened, but not its production in the brain; the second link of the association, viz. the stomach, acquires a greater share of it. In the latter case, by the continuation of the deficient stimulus of heat, the torpor becomes extended to the brain itself, or to the trunks of the nerves; and universal inactivity follows. 7. _Tussis a pedibus frigidis._ On standing with the feet in thawing snow, many people are liable to incessant coughing. From the torpidity of the absorbent vessels of the lungs, in consequence of their irritative associations with those of the skin, they cease to absorb the saline part of the secreted mucus; and a cough is thus induced by the irritation of this saline secretion; which is similar to that from the nostrils in frosty weather, but differs in respect to its immediate cause; the former being from association with a distant part, and the latter from defect of the stimulus of heat on the nostrils themselves. See Catarrhus frigidus, Class I. 2. 3. 3. 8. _Tussis hepatica._ The cough of inebriates, which attends the enlargement of the liver, or a chronical inflammation of its upper membrane, is supposed to be produced by the inconvenience the diaphragm suffers from the compression or heat of the liver. It differs however essentially from that attending hepatitis, from its not being accompanied with fever. And is perhaps rather owing to irritative association, or reverse sympathy, between the lungs and the liver. As occurs in sheep, which are liable to a perpetual dry cough, when the fleuk-worm is preying on the substance of their livers. See Class II. 1. 1. 5. M. M. From half a grain to a grain of opium twice a day. A drachm of mercurial ointment rubbed on the region of the liver every night for eight or ten times. 9. _Tussis arthritica._ Gout-cough. I have seen a cough, which twice recurred at a few years distance in the same person, during his fits of the gout, with such pertinacity and violence as to resist venesection, opiates, bark, blisters, mucilages, and all the usual methods employed in coughs. It was for a time supposed to be the hooping-cough, from the violence of the action of coughing; it continued two or three weeks, the patient never being able to sleep more than a few minutes at once during the whole time, and being propped up in bed with pillows night and day. As no fever attended this violent cough, and but little expectoration, and that of a thin and frothy kind, I suspected the membrane of the lungs to be rather torpid than inflamed, and that the saline part of the mucus not being absorbed stimulated them into perpetual exertion. And lastly, that though the lungs are not sensible to cold and heat, and probably therefore less mobile; yet, as they are nevertheless liable to consent with the torpor of cold feet, as described in Species 6 of this Genus, I suspected this torpor of the lungs to succeed the gout in the feet, or to act a vicarious part for them. 10. _Vertigo rotatoria._ In the vertigo from circumgyration the irritative motions of vision are increased; which is evinced from the pleasure that children receive on being rocked in a cradle, or by swinging on a rope. For whenever sensation arises from the production of irritative motion with less energy than natural, it is of the disagreeable kind, as from cold or hunger; but when it arises from their production with greater energy than natural, if it be confined within certain limits, it is of the pleasurable kind, as by warmth or wine. With these increased irritative motions of vision, I suppose those of the stomach are performed with greater energy by direct sympathy; but when the rotatory motions, which produce this agreeable vertigo, are continued too long, or are too violent, sickness of the stomach follows; which is owing to the decreased action of that organ from its reverse sympathy with the increased actions of the organ of vision. For the expenditure of sensorial power by the organ of vision is always very great, as appears by the size of the optic nerves; and is now so much increased as to deprive the next link of association of its due share. As mentioned in Article 6 of this Genus. In the same manner the undulations of water, or the motions of a ship, at first give pleasure by increasing the irritative motions belonging to the sense of vision; but produce sickness at length by expending on one part of the associated train of irritative actions too much of that sensorial power, which usually served the whole of it; whence some other parts of the train acquire too little of it, and perform their actions in consequence too feebly, and thence become attended with disagreeable sensation. It must also be observed, that when the irritative motions are stimulated into unusual action, as in inebriation, they become succeeded by sensation, either of the pleasurable or painful kind; and thus a new link is introduced between the irritative motions thus excited, and those which used to succeed them; whence the association is either dissevered or much weakened, and thus the vomiting in sea-sickness occurs from the defect of the power of association, rather than from the general deficiency of sensorial power. When a blind man turns round, or when one, who is not blind, revolves in the dark, a vertigo is produced belonging to the sense of touch. A blind man balances himself by the sense of touch, which being a less perfect means of determining small quantities of deviation from the perpendicular, occasions him to walk more carefully upright than those, who balance themselves by vision. When he revolves, the irritative associations of the muscular motions, which were used to preserve his perpendicularity, become disordered by their new modes of successive exertion; and he begins to fall. For his feet now touch the floor in manners or directions different from those they have been accustomed to; and in consequence he judges less perfectly of the situation of the parts of the floor in respect to that of his own body, and thus loses his perpendicular attitude. This may be illustrated by the curious experiment of crossing one finger over the next to it, and feeling of a nut or bullet with the ends of them. When, if the eyes be closed, the nut or bullet appears to be two, from the deception of the sense of touch. In this vertigo from gyration, both of the sense of sight, and of the sense of touch, the primary link of the associated irritative motions is increased in energy, and the secondary ones are increased at first by direct sympathy; but after a time they become decreased by reverse sympathy with the primary link, owing to the exhaustion of sensorial power in general, or to the power of association in particular; because in the last case, either pleasurable or painful sensation has been introduced between the links of a train of irritative motions, and has dissevered, or much enfeebled them. Dr. Smyth, in his Essay on Swinging in Pulmonary Consumption, has observed, that swinging makes the pulse slower. Dr. Ewart of Bath confirmed this observation both on himself and on Col. Cathcart, who was then hectic, and that even on shipboard, where some degree of vertigo might be supposed previously to exist. Dr. Currie of Liverpool not only confirmed this observation frequently on himself, when he was also phthisical, but found that equitation had a similar effect on him, uniformly retarding his pulse. This curious circumstance cannot arise from the general effect of exercise, or fatigue, as in those cases the pulse becomes weaker and quicker; it must therefore be ascribed to a degree of vertigo, which attends all those modes of motion, which we are not perpetually accustomed to. Dr. Currie has further observed, that "in cases of great debility the voluntary muscular exertion requisite in a swing produces weariness, that is, increases debility; and that in such instances he had frequently noticed, that the diminution of the frequency of the pulse did not take place, but the contrary." These circumstances may thus be accounted for. The links of association, which are effected in the vertigo occasioned by unusual motion, are the irritative motions of the sense of vision, those of the stomach, and those of the heart and arteries. When the irritative ideas of vision are exerted with greater energy at the beginning of vertigo, a degree of sensation is excited, which is of the pleasurable kind, as above mentioned; whence the associated trains of irritative motions of the stomach, and heart, and arteries, act at first with greater energy, both by direct sympathy; and by the additional sensorial power of sensation. Whence the pulse of a consumptive patient becomes stronger and consequently slower. But if this vertigo becomes much greater in degree or duration, the first link of this train of associated irritative motions expends too much of the sensorial power, which was usually employed on the whole train; and the motions of the stomach become in consequence exerted with less energy. This appears, because in this degree of vertigo sickness supervenes, as in sea-sickness, which has been shewn to be owing to less energetic action of the stomach. And the motions of the heart and arteries then become weaker, and in consequence more frequent, by their direct sympathy with the lessened actions of the stomach. See Supplement, I. 12. and Class II. 1. 6. 7. The general weakness from fatigue is owing to a similar cause, that is, to the too great expenditure of sensorial power in the increased actions of one part of the system, and the consequent deficiency of it in other parts, or in the whole. The abatement of the heat of the skin in hectic fever by swinging, is not only owing to the increased ventilation of cool air, but to the reverse sympathy of the motions of the cutaneous capillaries with those of the heart and arteries; which occurs in all fevers with arterial debility, and a hot or dry skin. Hence during moderate swinging the action of the heart and arteries becomes stronger and slower, and the action of the capillaries, which was before too great, as appeared by the heat of the skin, now is lessened by their reverse sympathy with that of the heart and arteries. See Supplement, I. 8. 11. _Vertigo visualis._ Visual vertigo. The vertigo rotatoria described above, was induced by the rotation or undulation of external objects, and was attended with increased action of the primary link of the associated motions belonging to vision, and with consequent pleasure. The vertigo visualis is owing to less perfect vision, and is not accompanied with pleasurable sensation. This frequently occurs in strokes of the palsy, and is then succeeded by vomiting; it sometimes precedes epileptic fits, and often attends those, whose sight begins to be impaired by age. In this vertigo the irritative ideas of the apparent motions of objects are less distinct, and on that account are not succeeded by their usual irritative associations of motion; but excite our attention. Whence the objects appear to librate or circulate according to the motions of our heads, which is called dizziness; and we lose the means of balancing ourselves, or preserving our perpendicularity, by vision. So that in this vertigo the motions of the associated organs are decreased by direct sympathy with their primary link of irritation; as in the preceding case of sea-sickness they are decreased by reverse sympathy. When vertigo affects people about fifty years of age, their sight has generally been suddenly impaired; and from their less accurate vision they do not soon enough perceive the apparent motions of objects; like a person in a room, the walls of which are stained with the uniform figures of lozenges, explained in Sect. XX. 1. This is generally ascribed to indigestion; but it ceases spontaneously, as the patient acquires the habit of balancing himself by less distinct objects. A gentleman about 50 was seized with an uncommon degree of vertigo, so as to fall on the ground, and not to be able to turn his head, as he sat up either in his chair or in his bed, and this continued eight or ten weeks. As he had many decayed teeth in his mouth, and the vertigo was preceded and sometimes accompanied by pains on one side of his head, the disease of a tooth was suspected to be the cause. And as his timidity was too great to admit the extraction of those which were decayed; after the trial of cupping repeatedly, fomentations on his head, repeated blisters, with valerian, Peruvian bark, musk, opium, and variety of other medicines; mercurials were used, both externally and internally, with design to inflame the membranes of the teeth, and by that means to prevent the torpor of the action of the membranes about the temple, and parietal bone; which are catenated with the membranes of the teeth by irritative association, but not by sensitive association. The event was, that as soon as the gums became sore with a slight ptyalism, the pains about the head and vertigo gradually diminished, and during the soreness of his gums entirely ceased; but I believe recurred afterwards, though in less degree. The idea of inflaming the membranes of the teeth to produce increased sensation in them, and thus to prevent their irritative connection with those of the cranium, was taken from the treatment of trismus, or locked jaw, by endeavouring to inflame the injured tendon; which is said to prevent or to remove the spasm of the muscles of the jaw. See Class III. 1. 1. 13. and 15. M. M. Emetics. Blisters. Issues about the head. Extraction of decayed teeth. Slight salivation. Sorbentia. Incitantia. 12. _Vertigo ebriosa._ Vertigo from intoxication is owing to the association of the irritative ideas of vision with the irritative motions of the stomach. Whence when these latter become much increased by the immoderate stimulus of wine, the irritative motions of the retina are produced with less energy by reverse sympathy, and become at the same time succeeded by sensation in consequence of their decreased action. See Sect. XXI. 3. and XXXV. 1. 2. So conversely when the irritative motions of vision are increased by turning round, or by our unaccustomed agitation at sea, those of the stomach become inverted by reverse sympathy, and are attended in consequence with disagreeable sensation. Which decreased action of the stomach is in consequence of the increased expenditure of the sensorial power on the irritative ideas of vision, as explained in Vertigo rotatoria. Whence though a certain quantity of vinous spirit stimulates the whole system into increased action, and perhaps even increases the secretion of sensorial power in the brain; yet as soon as any degree of vertigo is produced, it is a proof, that by the too great expenditure of sensorial power by the stomach, and its nearest associated motions, the more distant ones, as those of vision, become imperfectly exerted. From hence may be deduced the necessity of exhibiting wine in fevers with weak pulse in only appropriated quantity; because if the least intoxication be induced, some part of the system must act more feebly from the unnecessary expenditure of sensorial power. 13. _Vertigo febriculosa._ Vertigo in fevers either proceeds from the general deficiency of sensorial power belonging to the irritative associations, or to a greater expenditure of it on some links of the trains and tribes of associated irritative motions. There is however a slighter vertigo attending all people, who have been long confined in bed, on their first rising; owing to their having been so long unused to the apparent motions of objects in their erect posture, or as they pass by them, that they have lost in part the habit of balancing themselves by them. 14. _Vertigo cerebrosa._ Vertigo from injuries of the brain, either from external violence, or which attend paralytic attacks, are owing to the general deficiency of sensorial power. In these distressful situations the vital motions, or those immediately necessary to life, claim their share of sensorial power in the first place, otherwise the patient must die; and those motions, which are less necessary, feel a deficiency of it, as these of the organs of sense and muscles; which constitute vertigo; and lastly the voluntary motions, which are still less immediately necessary to life, are frequently partially destroyed, as in palsy; or totally, as in apoplexy. 15. _Murmur aurium vertiginosum._ The vertiginous murmur in the ears, or noise in the head, is compared to the undulations of the sound of bells, or to the humming of bees. It frequently attends people about 60 years of age; and like the visual vertigo described above is owing to our hearing less perfectly from the gradual inirritability of the organ on the approach of age; and the disagreeable sensation of noise attending it is owing to the less energetic action of these irritative motions; which not being sufficiently distinct to excite their usual associations become succeeded by our attention, like the indistinct view of the apparent motions of objects mentioned in vertigo visualis. This may be better understood from considering the use, which blind men make of these irritative sounds, which they have taught themselves to attend to, but which escape the notice of others. The late blind Justice Fielding walked for the first time into my room, when he once visited me, and after speaking a few words said, "this room is about 22 feet long, 18 wide, and 12 high;" all which he guessed by the ear with great accuracy. Now if these irritative sounds from the partial loss of hearing do not correspond with the size or usual echoes of the places, where we are; their catenation with other irritative ideas, as those of vision, becomes dissevered or disturbed; and we attend to them in consequence, which I think unravels this intricate circumstance of noises being always heard in the head, when the sense of hearing begins to be impaired, from whatever cause it occurs. This ringing in the ears also attends the vertigo from intoxication; for the irritative ideas of sound are then more weakly excited in consequence of the deficiency of the sensorial power of association. As is known by this also being attended with disagreeable sensation, and by its accompanying other diseases of debility, as strokes on the head, fainting fits, and paralytic seizures. For in this vertigo from intoxication so much sensorial power in general is expended on the increased actions of the stomach, and its nearest connections, as the capillaries of the skin; that there is a deficiency for the purposes of the other irritative associations of motions usually connected with it. This auditory vertigo attends both the rotatory and the visual vertigo above mentioned; in the former it is introduced by reverse sympathy, that is, by the diminution of sensorial power; too great a quantity of it being expended on the increased irritative motions of vision; in the latter it is produced either by the same causes which produce the visual vertigo, or by direct sympathy with it. See Sect. XX. 7. M. M. Stimulate the internal ear by ether, or with essential oil diluted with expressed oil, or with a solution of opium in wine, or in water. Or with salt and water. 16. _Tactus, gustus, olfactius vertiginosi._ Vertiginous touch, taste, and smell. In the vertigo of intoxication, when the patient lies down in bed, it sometimes happens even in the dark, that the bed seems to librate under him, and he is afraid of falling out of it. The same occurs to people, who are sea-sick, even when they lie down in the dark. In these the irritative motions of the nerves of touch, or irritative tangible ideas, are performed with less energy, in one case by reverse sympathy with the stomach, in the other by reverse sympathy with the nerves of vision, and in consequence become attended with sensation, and produce the fear of falling by other associations. A vertigo of the sense of touch may be produced, if any one turns round for a time with his eyes shut, and suddenly stops without opening them; for he will for a time seem to be still going forwards; which is difficult to explain. See the notes at the end of the first and second volume belonging to Sect. XX. 6. In the beginning of some fevers, along with incessant vomiting, the patients complain of disagreeable tastes in their mouth, and disagreeable odours; which are to be ascribed to the general debility of the great trains and tribes of associated irritative motions, and to be explained from their direct sympathy with the decreased action of a sick stomach; or from the less secretion of sensorial power in the brain. These organs of sense are constantly stimulated into action by the saliva or by the air; hence, like the sense of hunger, when they are torpid from want of stimulus, or from want of sensorial power, pain or disagreeable sensation ensues, as of hunger, or faintness, or sickness in one case; and the ideas of bad tastes or odours in the other. This accords with the laws of causation, Sect. IV. 5. 17. _Pulsus mollis in vomitione._ The softness of the pulse in the act of vomiting is caused by direct association between the heart and the stomach; as explained in Sect. XXV. 17. A great slowness of the pulsation of the heart sometimes attends sickness, and even with intermissions of it, as in the exhibition of too great a dose of digitalis. 18. _Pulsus intermittens a ventriculo._ When the pulse first begins to intermit, it is common for the patient to bring up a little air from his stomach; which if he accomplishes before the intermission occurs, always prevents it; whence that this debility of the heart is owing to the direct association of its motions with those of the stomach is well evinced. See Sect. XXV. 17. I this morning saw Mr. ----, who has long had at times an unequal pulse, with indigestion and flatulency, and occasional asthma; he was seized two days ago with diarrhoea, and this morning with sickness, and his pulse was every way unequal. After an emetic his pulse still continued very intermittent and unequal. He then took some breakfast of toast and butter, and tea, and to my great surprise his pulse became immediately perfectly regular, about 100 in a minute, and not weak, by this stimulus on his stomach. A person, who for many years had had a frequent intermission of his pulse, and occasional palpitation of his heart, was relieved from them both for a time by taking about four drops of a saturated solution of arsenic three or four times a day for three or four days. As this intermission of the pulse is occasioned by the direct association of the motions of the heart with those of the stomach, the indication of cure must be to strengthen the action of the stomach by the bark. Spice. Moderate quantities of wine. A blister. Half a grain of opium twice a day. Solution of arsenic? 19. _Febris inirritativa._ Inirritative fever described in Class I. 2. 1. 1. belongs to this place, as it consists of disordered trains and tribes of associated irritative motions, with lessened actions of the associated organs. In this fever the pulsations of the heart and arteries are weakened or lessened, not only in the cold paroxysm, as in the irritative fever, but also in the hot paroxysm. The capillary arteries or glands have their actions nevertheless increased after the first cold fit, as appears by the greater production of heat, and the glow of arterial blood, in the cutaneous vessels; and lastly, the action of the stomach is much impaired or destroyed, as appears by the total want of appetite to solid food. Whence it would seem, that the torpid motions of the stomach, whatever may occasion them, are a very frequent cause of continued fever with weak pulse; and that these torpid motions of the stomach do not sufficiently excite the sensorial power of association, which contributes in health to actuate the heart and arteries along with the irritation produced by the stimulus of the blood; and hence the actions of these organs are weaker. And lastly, that the accumulation of the sensorial power of association, which ought to be expended on the motions of the heart and arteries, becomes now exerted on the cutaneous and pulmonary capillaries. See Supplement I. 8. and Sect. XXXV. 1. 1. and XXXIII. 2. 10. I have dwelt longer on the vertiginous diseases in this genus, both because of their great intricacy, and because they seem to open a road to the knowledge of fever, which consists of associated trains and tribes of irritative or sensitive motions, which are sometimes mixed with the vertiginous ones, and sometimes separate from them. * * * * * ORDO II. _Decreased Associate Motions._ GENUS II. _Catenated with Sensitive Motions._ In this genus the sensorial power of association is exerted with less energy, and thence the actions produced by it are less than natural; and pain is produced in consequence, according to the fifth law of animal causation, Sect. IV. This pain is generally attended with coldness of the affected part, and is seldom succeeded by inflammation of it. This decreased action of the secondary link of the associated motions, belonging to this genus, is owing to the previous exhaustion of sensorial power either in the increased actions of the primary link of the associated motions, or by the pain which attends them; both which are frequently the consequence of the stimulus of something external to the affected fibres. As pain is produced either by excess or defect of the natural exertions of the fibres, it is not, considered separately, a criterion of the presence of either. In the associations belonging to this genus the sensation of pain or pleasure produces or attends the primary link of the associated motions, and very often gives name to the disease. When great pain exists without causing any fibrous motions, I conjecture that it contributes to exhaust or expend the general quantity of sensorial power; because people are fatigued by enduring pain, till at length they sleep. Which is contrary to what I had perhaps erroneously supposed in Sect. XXXV. 2. 3. If it causes fibrous motions, it then takes the name of sensation, according to the definition of sensation in Sect. II. 2. 9.; and increased fibrous action or inflammation is the consequence. This circumstance of the general exhaustion of sensorial power by the existence of pain will assist in explaining many of the diseases of this genus. Many of the canals of the body, as the urethra, the bile-duct, the throat, have the motions of their two extremities associated by having been accustomed to feel pleasurable or painful sensations at the same time or in succession. This is termed sensitive association, though those painful or pleasurable sensations do not cause the motions, but only attend them; and are thus perhaps, strictly speaking, only catenated with them. SPECIES. 1. _Torpor genæ a dolore dentis._ In tooth-ach there is generally a coldness of the cheek, which is sensible to the hand, and is attended in some degree with the pain of cold. The cheek and tooth have frequently been engaged in pleasurable action at the same time during the masticating of our food; whence they have acquired sensitive associations. The torpor of the cheek may have for its cause the too great expenditure of sensorial power by the painful sensation of the membranes of the diseased tooth; whence the membranes of the cheek associated with those of the alveolar process are deprived of their natural share of it, and become torpid; thus they produce less secretions, and less heat, and the pain of cold is the consequence. This torpor of the vessels of the cheek cannot be produced by the activity of the sensorial power of sensation; for then they would act more violently than natural, or become inflamed. And though the pain by exhausting so much sensorial power may be a remote cause, it is the defeat of the power of association, which is the immediate cause of the torpor of the cheek. After some hours this pain occasioned by the torpor of the vessels of the cheek either gradually ceases along with the pain of the diseased tooth; or, by the accumulation of sensorial power during their state of torpor, the capillaries of the cheek act with greater violence, and produce more secretions, and heat, and consequent tumour, and inflammation. In this state the pain of the diseased tooth ceases; as the sensorial power of sensation is now expended on the inflamed vessels of the cheek. It is probable that most other internal membranous inflammations begin in a similar manner; whence there may seem to be a double kind of sensitive association; first, with decreased action of the associated organ, and then with increased action of it; but the latter is in this case simply the consequence of the former; that is, the tumor or inflammation of the cheek is in consequence of its previous quiescence or torpor. 2. _Stranguria a dolore vesicæ._ The strangury, which has its origin from pain at the neck of the bladder, consists of a pain in the external extremity of the urethra or of the glans penis of men, and probably in the external termination of the urethra or of the clitoris of women; and is owing to the sympathy of these with some distant parts, generally with the other end of the urethra; an endeavour and difficulty of making water attends this pain. Its remote cause is from the internal or external use of cantharides, which stimulate the neck of the bladder; or from a stone, which whenever it is pushed into the neck of the bladder, gives this pain of strangury, but not at other times; and hence it is felt most severely in this case after having made water. The sensations or sensitive motions of the glans penis, and of the sphincter of the bladder, have been accustomed to exist together during the discharge of the urine; and hence the two ends of the urethra sympathize by association. When there is a stone at the neck of the bladder, which is not so large or rough as to inflame the part, the sphincter of the bladder becomes stimulated into pain; but as the glans penis is for the purposes of copulation more sensitive than the sphincter of the bladder, as soon as it becomes affected with pain by the association above mentioned, the sensation at the neck of the bladder ceases; and then the pain of the glans penis would seem to be associated with the irritative motions only of the sphincter of the bladder, and not with the sensitive ones of it. But a circumstance similar to this occurs in epileptic fits, which at first are induced by disagreeable sensation, and afterwards seem to occur without previous pain, from the suddenness in which they follow and relieve the pain, which occasioned them. From this analogy I imagine the pain of the glans penis is associated with the pain of the sphincter of the bladder; but that _as soon as the greater pain in a more sensible part is produced; the lesser one, which occasioned it, ceases_; and that this is one of the laws of sensitive association. See Sect. XXXV. 2. 1. A young man had by an accident swallowed a large spoonful or more of tincture of cantharides; as soon as he began to feel the pain of strangury, he was advised to drink large quantities of warmish water; to which, as soon as it could be got, some gum arabic was added. In an hour or two he drank by intervals of a few minutes about two gallons of water, and discharged his urine every four or five minutes. A little blood was voided towards the end, but he suffered no ill consequence. M. M. Warm water internally. Clysters of warm water. Fomentation. Opium. Solution of fixed alkali supersaturated with carbonic acid. A bougie may be used to push back a stone into the bladder. See Class I. 1. 3. 10. 3. _Stranguria convulsiva._ The convulsive strangury, like that before described, is probably occasioned by the torpor or defective action of the painful part in consequence of the too great expenditure of sensorial power on the primary link of the associated motions, as no heat or inflammation attends this violent pain. This kind of strangury recurs by stated periods, and sometimes arises to so great a degree, that convulsion or temporary madness terminates each period of it. It affects women oftener than men, is attended with cold extremities without fever, and is distinguished from the stone of the bladder by the regularity of its periods, and by the pain being not increased after making water. On introducing the catheter sometimes part of the urine will come away and not the whole, which is difficult to explain; but may arise from the weakness of the muscular fibres of the bladder; which are not liable suddenly to contract themselves so far as to exclude the whole of the urine. In some old people, who have experienced a long retention of urine, the bladder never regains the power of completely emptying itself; and many who are beginning to be weak from age can make water a second time, a few minutes after they supposed they had emptied the bladder. I have believed this pain to originate from sympathy with some distant part, as from ascarides in the rectum, or from piles in women; or from caruncles in the urethra about the caput gallinaginis in men; and that the pain has been in the glans or clitoris by reverse sympathy of these more sensible parts with those above mentioned. M. M. Venesection. Opium in large quantities. Warm bath. Balsams. Bark. Tincture of cantharides. Bougie, and the treatment for hæmorrhoids. Leeches applied to the sphincter ani. Aerated alcaline water. Soap and sal soda. Opium in clysters given an hour before the expected return. Smoke of tobacco in clysters. Arsenic? 4. _Dolor termini intestinalis ductûs choledochi._ Pain at the intestinal end of the gall-duct. When a gall-stone is protruded from the gall-bladder a little way into the end of the gall-duct, the pain is felt at the other end of the gall-duct, which terminates in the duodenum. For the actions of the two terminations of this canal are associated together from the same streams of bile passing through them in succession, exactly as the two terminations of the urethra have their actions associated, as described in Species 2 and 3 of this genus. But as the intestinal termination of the bile-duct is made more sensible for the purpose of bringing down more bile, when it is stimulated by new supplies of food from the stomach, it falls into violent pain from association; and then the pain on the region of the gall-bladder ceases, exactly as above explained in the account of the pain of the glans penis from a stone in the sphincter of the bladder. The common bile-duct opens into the intestine exactly at what is called the pit of the stomach; and hence it has sometimes happened, that this pain from association with the sensation of a gall-stone at the other end of the bile-duct has been mistaken for a pain of the stomach. For the method of cure see Class I. 1. 3. 8. to which should be added the use of strong electric shocks passed through the bile-duct from the pit of the stomach to the back, and from one side to the other. A case of the good effect of electricity in the jaundice is related in Sect. XXX. 2. And another case, where it promoted the passage of a painful gall-stone, is described by Dr. Hall, experienced on himself. Trans. of the College at Philadelphia, Vol. I. p. 192. Half a pint of warm water two or three times a day is much recommended to dilute the inspissated bile. 5. _Dolor pharyngis ab acido gastrico._ The two ends of the throat sympathize by sensitive association in the same manner as the other canals above mentioned, namely, the urethra and the bile-duct; hence when too great acidity of undigested aliment, or the carbonic acid air, which escapes in fermentation, stimulates the cardia ventriculi, or lower end of the gula, into pain; the pharinx, or upper end of it, is affected with greater pain, or a disagreeable sensation of heat. 6. _Pruritus narium a vermibus._ The itching of the nose from worms in the intestines is another curious instance of the sensitive associations of the motions of membranes; especially of those which constitute the canals of the body. Previous to the deglutition of agreeable food, as milk in our earliest infancy, an agreeable odour affects the membrane, which lines the nostrils; and hence an association seems to take place between the agreeable sensations produced by food in the stomach and bowels, and the agreeable sensations of the nostrils. The existence of ascarides in the rectum I believe produces this itching of the nostrils more than the worms in other parts of the intestines; as we have already seen, that the terminations of canals sympathize more than their other parts, as in the urethra and gall-ducts. See Class I. 1. 5. 9. IV. 1. 2. 9. 7. _Cephalæa._ Head-ach. In cold fits of the ague, the head-ach arises from consent with some torpid viscus, like the pain of the loins. After drunkenness the head-ach is very common, owing to direct sympathy of the membranes of the head with those of the stomach; which is become torpid after the too violent stimulus of the preceding intoxication; and is hence removeable by spirit of wine, or opium, exhibited in smaller quantities. In some constitutions these head-achs are induced, when the feet are exposed to much external cold; in this case the feet should be covered with oiled silk, which prevents the evaporation of the perspirable matter, and thence diminishes one cause of external cold. M. M. Valerian in powder two drams three or four times a day is recommended. The bark. Chalybeates. A grain of opium twice a day for a long time. From five to ten drops of the saturated solution of arsenic two or three times a day. See Class I. 2. 4. 11. A lady once assured me, that when her head-ach was coming on, she drank three pints (pounds) of hot water, as hastily as she could; which prevented the progress of the disease. A solution of arsenic is recommended by Dr. Fowler of York. Very strong errhines are said sometimes to cure head-achs taken at the times the pain recurs, till a few drops of blood issue from the nostrils. As one grain of turpeth mineral (vitriolic calx of mercury) mixed with ten grains of fine sugar. Euphorbium or cayan pepper mixed with sugar, and used with caution as an errhine. See the M. M. of the next Species. 8. _Hemicrania._ Pain on one side of the head. This disease is attended with cold skin, and hence whatever may be the remote cause, the immediate one seems to be want of stimulus, either of heat or distention, or of some other unknown stimulus in the painful part; or in those, with which it is associated. The membranes in their natural state are only irritable by distention; in their diseased state, they are sensible like muscular fibres. Hence a diseased tooth may render the neighbouring membranes sensible, and is frequently the cause of this disease. Sometimes the stomach is torpid along with the pained membrane of the head; and then sickness and inappetency attends either as a cause or consequence. The natural cure of hemicrania is the accumulation of sensorial power during the rest or sickness of the patient. Mrs. ---- is frequently liable to hemicrania with sickness, which is probably owing to a diseased tooth; the paroxysm occurs irregularly, but always after some previous fatigue, or other cause of debility. She lies in bed, sick, and without taking any solid food, and very little of fluids, and those of the aqueous kind, and, after about 48 or 50 hours, rises free from complaint. Similar to this is the recovery from cold paroxysms of fever, from the torpor occasioned by fear, and from syncope; which are all owing to the accumulation of sensorial power during the inactivity of the system. Hence it appears, that, though when the sensorial power of volition is much exhausted by fatigue, it can be restored by eight or ten hours of sleep; yet, when the sensorial power of irritation is exhausted by fatigue, that it requires two whole solar or lunar days of rest, before it can be restored. The late Dr. Monro asserted in his lectures, that he cured the hemicrania, or megrim, by a strong vomit, and a brisk purge immediately after it. This method succeeds best if opium and the bark are given in due quantity after the operation of the cathartic; and with still more certainty, if bleeding in small quantity is premised, where the pulse will admit of it. See Sect. XXXV. 2. 1. The pain generally affects one eye, and spreads a little way on that side of the nose, and may sometimes be relieved by pressing or cutting the nerve, where it passes into the bone of the orbit above the eye. When it affects a small defined part on the parietal bone on one side, it is generally termed Clavus hystericus, and is always I believe owing to a diseased dens molaris. The tendons of the muscles, which serve the office of mastication, have been extended into pain at the same time, that the membranous coverings of the roots of the teeth have been compressed into pain, during the biting or mastication of hard bodies. Hence when the membranes, which cover the roots of the teeth, become affected with pain by a beginning decay, or perhaps by the torpor or coldness of the dying part of the tooth, the tendons and membranous fascia of the muscles about the same side of the head become affected with violent pain by their sensitive associations: and as soon as this associated pain takes place, the pain of the tooth entirely ceases, as explained in the second species of this genus. A remarkable circumstance attends this kind of hemicrania, viz. that it recurs by periods like those of intermittent fevers, as explained in the Section on Catenation of Motions; these periods sometimes correspond with alternate lunar or solar days like tertian agues, and that even when a decaying tooth is evidently the cause; which has been evinced by the cure of the disease by extracting the tooth. At other times they observe the monthly lunations, and seem to be induced by the debility, which attends menstruation. The dens sapientiæ, or last tooth of the upper jaw, frequently decays first, and gives hemicrania over the eye on the same side. The first or second grinder in the under-jaw is liable to give violent pain about the middle of the parietal bone, or side of the head, on the same side, which is generally called the Clavus hystericus, of which an instructive case is related in Sect. XXXV. 2. 1. M. M. Detect and extract the diseased tooth. Cut the affected nerve, or stimulate the diseased membrane by acu-puncture. Venesection to six ounces by the lancet or by leeches. A strong emetic and a subsequent cathartic; and then an opiate and the bark. Pass small electric shocks through the pained membrane, and through the teeth on the same side. Apply vitriolic ether externally, and a grain of opium with camphor internally, to the cheek on the affected side, where a diseased tooth may be suspected. Foment the head with warm vinegar. Drink two large spoonfuls of vinegar. Stimulate the gums of the suspected teeth by oil of cloves, by opium. See Class I. 1. 4. 4. Snuff volatile spirit of vinegar up the nostrils. Lastly, in permanent head-achs, as in permanent vertigo, I have seen good effect by the use of mercurial ointment rubbed on the shaved head or about the throat, till a mild salivation commences, which by inflaming the membranes of the teeth may prevent their irritative sympathy with those of the cranium. Thus by inflaming the tendon, which is the cause of locked jaw, and probably by inflaming the wound, which is the cause of hydrophobia, those diseases may be cured, by disuniting the irritative sympathy between those parts, which may not possess any sensitive sympathy. This idea is well worth our attention. _Otalgia._ Ear-ach is another disease occasioned by the sympathy of the membranes of the ear with those which invest or surround a decaying tooth, as I have had frequent reason to believe; and is frequently relieved by filling the ear with tincture of opium. See Class I. 2. 4. 9. _Dolor humeri in hepatitide._ In the efforts of excluding the fæces and urine the muscles of the shoulders are exerted to compress the air in the lungs, that the diaphragm may be pressed down. Hence the distention of the tendons or fibres of these muscles is associated with the distention of the tendons or fibres of the diaphragm; and when the latter are pained by the enlargement or heat of the inflamed liver, the former sympathize with them. Sometimes but one shoulder is affected, sometimes both; it is probable that many other pains, which are termed rheumatic, have a similar origin, viz. from sensitive associations. As no inflammation is produced in consequence of this pain of the shoulder, it seems to be owing to inaction of the membranous part from defect of the sensorial power of association, of which the primary link is the inflamed membrane of the liver; which now expends so much of the sensorial power in general by its increased action, that the membranes about the shoulder, which are links of association with it, become deprived of their usual share, and consequently fall into torpor. 10. _Torpor pedum in eruptione variolarum._ At the commencement of the eruption of the small-pox, when the face and breast of children are very hot, their extremities are frequently cold. This I ascribe to sensitive association between the different parts of the skin; whence when a part acts too violently, the other part is liable to act too weakly; and the skin of the face being affected first in the eruption of the small-pox, the skin of the feet becomes cold in consequence by reverse sympathy. M. M. Cover the feet with flannel, and expose the face and bosom to cool air, which in a very short time both warms the feet and cools the face; and hence what is erroneously called a rash, but which is probably a too hasty eruption of the small-pox, disappears; and afterwards fewer and more distinct eruptions of the small-pox supervene. 11. _Testium dolor nephriticus._ The pain and retraction of the testicle on the same side, when there is a stone in the ureter, is to be ascribed to sensitive association; whether the connecting cause be a branch of the same nerve, or from membranes, which have been frequently affected at the same time. 12. _Dolor digiti minimi sympatheticus._ When any one accidentally strikes his elbow against any hard body, a tingling pain runs down to the little finger end. This is owing to sensitive association of motions by means of the same branch of a nerve, as in hemicrania from a decaying tooth the pain is owing to the sensitive association of tendons or membranes. 13. _Dolor brachii in hydrope pectoris._ The pain in the left arm which attends some dropsies of the chest, is explained in Sect. XXIX. 5. 2. 10. which resembles the pain of the little finger from a percussion of the nerve at the elbow in the preceding article. A numbness of this kind is produced over the whole leg, when the crural nerve is much compressed by sitting for a time with one leg crossed over the other. Mr. ----, about sixty, had for two years been affected with difficulty of respiration on any exertion, with pain about the sternum, and of his left arm; which last was more considerable than is usual in dropsy of the chest; some months ago the pain of his arm, after walking a mile or two, became excessive, with coldness and numbness; and on the next day the back of the hand, and a part of the arm swelled, and became inflamed, which relieved the pain; and was taken for the gout, and continued several days. He after some months became dropsical both in respect to his chest and limbs, and was six or seven times perfectly relieved by one dram of saturated tincture of digitalis, taken two or three times a day for a few days in a glass of peppermint water. He afterwards breathed oxygen gas undiluted, in the quantity of six or eight gallons a day for three or four weeks without any effect, and sunk at length from general debility. In this instructive case I imagine the pressure or stimulus of one part of the nerve within the chest caused the other part, which serves the arm, to become torpid, and consequently cold by sympathy; and that the inflammation was the consequence of the previous torpor and coldness of the arm, in the same manner as the swelling and inflammation of the cheek in tooth-ach, in the first species of this genus; and that many rheumatic inflammations are thus produced by sympathy with some distant part. 14. _Diarrhoea a dentitione._ The diarrhoea, which frequently attends dentition, is the consequence of indigestion; the aliment acquires chemical changes, and by its acidity acts as a cathartic; and changes the yellow bile into green, which is evacuated along with indigested parts of the coagulum of milk. The indigestion is owing to the torpor of the stomach and intestines caused by their association with the membranes of the gums, which are now stimulated into great exertion with pain; both which contribute to expend the general quantity of sensorial power, which belongs to this membranous association; and thus the stomach and intestines act with less than their natural energy. This is generally esteemed a favourable symptom in difficult dentition, as the pain of the alveolar membranes exhausts the sensorial power without producing convulsions for its relief. See Class I. 1. 4. 5. And the diarrhoea ceases, as the tooth advances. * * * * * ORDO II. _Decreased Associate Motions._ GENUS III. _Catenated with Voluntary Motions._ SPECIES. 1. _Titubatio linguæ._ Impediment of speech is owing to the associations of the motions of the organs of speech being interrupted or dissevered by ill-employed sensation or sensitive motions, as by awe, bashfulness, ambition of shining, or fear of not succeeding, and the person uses voluntary efforts in vain to regain the broken associations, as explained in Sect. XVII. 1. 10. and XVII. 2. 10. The broken association is generally between the first consonant and the succeeding vowel; as in endeavouring to pronounce the word parable, the p is voluntarily repeated again and again, but the remainder of the word does not follow, because the association between it and the next vowel is dissevered. M. M. The art of curing this defect is to cause the stammerer to repeat the word, which he finds difficult to speak, eight or ten times without the initial letter, in a strong voice, or with an aspirate before it, as arable, or harable; and at length to speak it very softly with the initial letter p, parable. This should be practised for weeks or months upon every word, which the stammerer hesitates in pronouncing. To this should be added much commerce with mankind, in order to acquire a carelessness about the opinions of others. 2. _Chorea St. Viti._ In the St. Vitus's dance the patient can at any time lie still in bed, which shews the motions not to be convulsive; and he can at different times voluntarily exert every muscle of his body; which evinces, that they are not paralytic. In this disease the principal muscle in any designed motion obeys the will; but those muscles, whose motions were associated with the principal one, do not act; as their association is dissevered, and thus the arm or leg is drawn outward, or inward, or backward, instead of upward or forward, with various gesticulations exactly resembling the impediment of speech. This disease is frequently left after the itch has been too hastily cured. See Convulsio dolorifica, Class III. 1. 1. 6. A girl about eighteen, after wearing a mercurial girdle to cure the itch, acquired the Chorea St. Viti in so universal a manner, that her speech became affected as well as her limbs; and there was evidently a disunion of the common trains of ideas; as the itch was still among the younger children of the family, she was advised to take her sister as a bedfellow, and thus received the itch again; and the dance of St. Vitus gradually ceased. See Class II. 1. 5. 6. M. M. Give the patient the itch again. Calomel a grain every night, or sublimate a quarter of a grain twice a day for a fortnight. Steel. Bark. Warm-bath. Cold-bath. Opium. Venesection once at the beginning of the disease. Electricity. Perpetual slow and repeated efforts to move each limb in the designed direction, as in the titubatio linguæ above described. 3. _Risus._ Laughter is a perpetual interruption of voluntary exertion by the interposition of pleasurable sensation; which not being checked by any important consequences rises into pain, and requires to be relieved or moderated by the frequent repetition of voluntary exertion. See Sect. XXXIV. 1. 4. and Class III. 1. 1. 4. and IV. 1. 3. 3. 4. _Tremor ex irâ._ The trembling of the limbs from anger. The interruption of the voluntary associations of motions by anger, originates from too great a part of the sensorial power being exerted on the organs of sense; whence the muscles, which ought to support the body upright, are deprived of their due quantity, and tremble from debility. See Class III. 2. 1. 1. 5. _Rubor ex irâ._ Redness from anger. Anger is an excess of aversion, that is of voluntarity not yet employed. It is excited by the pain of offended pride; when it is employed it becomes outrage, cruelty, insanity. The cutaneous capillaries, especially those of the face, are more mobile, that is, more easily excited into increased action, or more easily become torpid, from less variation of sensorial power, than any other parts of the system, which is owing to their being perpetually subject to the vicissitudes of heat and cold, and of extension and corrugation. Hence, when an excess of voluntarity exists without being immediately expended in the actions of the large muscles, the capillary arteries and glands acquire more energetic action, and a flushed skin is produced, with increased secretion of perspirable matter, and consequent heat, owing to the pause or interruption of voluntary action; and thus the actions of these cutaneous vessels become associated between the irascent ideas and irascent muscular actions, which are thus for a time interrupted. 6. _Rubor criminati._ The blushing of accused people, whether guilty or not, appears to be owing to circumstances similar to that of anger; for in these situations there is always a sudden voluntarity, or wish, of clearing their characters arises in the mind of the accused person; which, before an opportunity is given for it to be expended on the large muscles, influences the capillary arteries and glands, as in the preceding article. Whence the increased actions of the capillaries, and the consequent redness and heat, become exerted between the voluntary ideas of self-defence, and the muscular actions necessary for that purpose; which last are thus for a time interrupted or delayed. Even in the blush of modesty or bashfulness there is a self-condemnation for some supposed defect or indecorum, and a sudden voluntarity, or wish, of self-defence; which not being expended in actions of the larger muscles excites the capillaries into action; which in these subjects are more mobile than in others. The blush of young girls on coming into an assembly room, where they expect their dress, and steps, and manner to be examined, as in dancing a minuet, may have another origin; and may be considered as a hot fit of returning confidence, after a previous cold fit of fear. 7. _Tarditas paralytica._ By a stroke of the palsy or apoplexy it frequently happens, that those ideas, which were associated in trains, whose first link was a voluntary idea, have their connection dissevered; and the patient is under the necessity by repeated efforts slowly to renew their associations. In this situation those words, which have the fewest other words associated with them, as the proper names of persons or places, are the most difficult to recollect. And in those efforts of recollection the word opposite to the word required is often produced, as hot for cold, winter for summer, which is owing to our associating our ideas of things by their opposites as well as by their similitudes, and in some instances perhaps more frequently, or more forcibly. Other paralytic patients are liable to give wrong names to external objects, as using the word pigs for sheep, or cows for horses; in this case the association between the idea of the animal and the name of it is dissevered; but the idea of the class or genus of the thing remains; and he takes a name from the first of the species, which presents itself, and sometimes can correct himself, till he finds the true one. 8. _Tarditas senilis._ Slowness of age. The difficulty of associating ideas increases with our age; as may be observed from old people forgetting the business of the last hour, unless they impress it strongly, or by frequent repetition, though they can well recollect the transactions of their youth. I saw an elderly man, who could reason with great clearness and precision and in accurate language on subjects, which he had been accustomed to think upon; and yet did not know, that he had rang the bell by his fire-side in one minute afterwards; nor could then recollect the object he had wanted, when his servant came. Similar to this is the difficulty which old people experience in learning new bodily movements, that is, in associating new muscular actions, as in learning a new trade or manufactury. The trains of movements, which obey volition, are the last which we acquire; and the first, which are disassociated. * * * * * ORDO II. _Decreased Associate Motions._ GENUS IV. _Catenated with External Influences._ As the diseases, which obey solar or lunar periods, commence with torpor or inactivity, such as the cold paroxysms of fevers, the torpor and consequent pain of hemicrania, and the pains which precede the fits of epilepsy and convulsion, it would seem, that these diseases are more generally owing to the diminution than to the excess of solar or lunar gravitation; as the diseases, which originate from the influence of the matter of heat, are much more generally in this country produced by the defect than by the excess of that fluid. The periodic returns of so many diseases coincide with the diurnal, monthly, and annual rounds of time; that any one, who would deny the influence of the sun and moon on the periods of quotidian, tertian, and quartan fevers, must deny their effect on the tides, and on the seasons. It has generally been believed, that solar and lunar effect was exerted on the blood; which was thus rendered more or less stimulant to the system, as described in Sect. XXXII. 6. But as the fluid matter of gravitation permeates and covers all things, like the fluid matter of heat; I am induced to believe, that gravitation acts in its medium state rather as a causa sine quâ non of animal motion, like heat; which may disorder the system chemically or mechanically, when it is diminished; but may nevertheless stimulate it, when increased, into animal exertion. Without heat and motion, which some philosophers still believe to be the same thing, as they so perpetually appear together, the particles of matter would attract and move towards each other, and the whole universe freeze or coalesce into one solid mass. These therefore counteract the gravitation of bodies to one center; and not only prevent the planets from falling into the sun, but become either the efficient causes of vegetable and animal life, or the causes without which life cannot exist; as by their means the component particles of matter are enabled to slide over each other with all the various degrees of fluidity and repulsion. As the attraction of the moon countervails or diminishes the terrene gravitation of bodies on the surface of the earth; a tide rises on that side of the earth, which is turned towards the moon; and follows it, as the earth revolves. Another tide is raised at the same time on the opposite side of the revolving earth; which is owing to the greater centrifugal motion of that side of the earth, which counteracts the gravitation of bodies near its surface. For the earth and moon may be considered as two cannon balls of different sizes held together by a chain, and revolving once a month round a common center of gravity between them, near the earth's surface; at the same time that they perform their annual orbits round the sun. Whence the centrifugal force of that side of the earth, which is farthest from this center of motion, round which the earth and moon monthly revolve, is considerably greater, than the centrifugal force of that side of the earth, which is nearest it; to which should be added, that this centrifugal force not only contributes to diminish the terrene gravitation of bodies on the earth's surface on that side furthest from this center of motion, but also to increase it on that side, which is nearest it. Another circumstance, which tends to raise the tide on the part of the earth's surface, which is most distant from the moon, is, that the attraction of the moon is less on that part of the ocean, than it is on the other parts of the earth. Thus the moon may be supposed to attract the water on the side of the earth nearest it with a power equal to three; and to attract the central parts of the earth with a power equal to two; and the water on the part of the earth most distant from the moon with a power only equal to one. Hence on the side of the earth most distant from the moon, the moon's attraction is less, and the centrifugal force round their common center of motion is greater; both which contribute to raise the tides on that side of the earth. On the side of the earth nearest the moon, the moon's attraction is so much greater as to raise the tides; though the centrifugal force of the surface of the earth round their common center of motion in some degree opposes this effect. On these accounts, when the moon is in the zenith or nadir, the gravitation of bodies on the earth's surface will be greatest at the two opposite quadratures; that is, the greatest gravitation of bodies on the earth's surface towards her center during the lunar day is about six hours and an half after the southing, or after the northing of the moon. Circumstances similar to these, but in a less degree, must occur in respect to the solar influence on terrestrial bodies; that is, there must be a diminution of the gravity of bodies, near the earth's surface at noon, when the sun is over them; and also at midnight from the greater centrifugal force of that side of the earth, which is most distant from the center, round which the earth moves in her annual orbit, than on the side nearest that center. Whence it likewise follows, that the gravitation of bodies towards the earth is greatest about six hours after noon, and after midnight. Now when the sun and moon have their united gravitation on the same side of the earth, as at the new moon; or when the solar attraction coincides with the greater centrifugal motion of that side of the earth, which is furthest distant from the moon, as at the full moon; and when this happens about noon or midnight, the gravitation of terrene bodies towards the earth will be greater about six hours after noon, and after midnight, than at any other part of the lunar period; because the attraction of both these luminaries is then exerted on those sides of the earth over which they hang, which at other times of the month are more or less exerted on other parts of it. Lastly, as heat and motion counteract the gravitation of the particles of bodies to each other, and hence become either the efficient causes of vegetable and animal life, or the causes without which life cannot exist, it seems to follow, that when our gravitation towards the earth's center is greatest, the powers of life should be the least; and hence that those diseases, which begin with torpor, should occur about six hours after the solar or lunar noon, or about six hours after the solar or lunar midnight; and this most frequently about six hours after or before the new or full moon; and especially when these happen at noon or at midnight; or lastly, according to the combination of these powers in diminishing or increasing the earth's attraction to bodies on its surface. The returns or exacerbations of many fevers, both irritative and inflammatory, about six in the evening, and of the periodic cough described in Sect. XXXVI. 3. 9. countenance this theory. Tables might be made out to shew the combined powers of the sun and moon in diminishing the gravitation of bodies on the earth's surface, at every part of their diurnal, monthly, and annual periods; and which might facilitate the elucidation of this subject. But I am well aware of the difficulty of its application to diseases, and hope these conjectures may induce others to publish more numerous observations, and more conclusive reasonings. SPECIES. 1. _Somni periodus._ The periods of sleeping and of waking are shortened or prolonged by so many other circumstances in animal life, besides the minute difference between diurnal and nocturnal solar gravitation, that it can scarcely be ascribed to this influence. At the same time it is curious to observe, that vegetables in respect to their times of sleeping more regularly observe the hour of the day, than the presence or absence of light, or of heat, as may be seen by consulting the calendar of Flora. Botanic Garden, Part II. Canto 2. l. 165. note. Some diseases, which at first sight might be supposed to be influenced by solar periods, seem to be induced by the increasing sensibility of the system to pain during our sleeping hours; as explained in Sect. XVIII. 15. Of these are the fits of asthma, of some epilepsies, and of some hæmoptoes; all which disturb the patient after some hours sleep, and are therefore to be ascribed to the increase of our dormant sensibility. There may likewise be some doubt, whether the commencement of the pain of gout in the foot, as it generally makes its attack after sleep, should be ascribed to the increased sensibility in sleep, or to solar influence? M. M. When asthmatic or epileptic fits or hæmoptoe occur after a certain number of hours of sleep, the patient should be forcibly awakened before the expected time by an alarm clock, and drink a cup of chocolate or lemonade.--Or a grain of opium should be given at going to bed.--In one case to prevent the too great increase of sensibility by shortening the time of sleep; and in the other by increasing the irritative motions, and expending by that means a part of the sensorial power. 2. _Studii inanis periodus._ Class III. 1. 2. 2. The cataleptic spasm which preceded the reverie and somnambulation in the patient, whose case is related in Sect. XIX. 2. occurred at exactly the same hour, which was about eleven in the morning for many weeks; till those periods were disturbed by large doses of opium; and must therefore be referred to some effect of solar gravitation. In the case of Master A. Sect. XXXIV. 3. as the reverie began early in the morning during sleep, there may be a doubt, whether this commenced with torpor of some organ catenated with solar gravitation; or was caused by the existence of a previous torpid part, which only became so painful as to excite the exertions of reverie by the perpetual increase of sensibility during the continuance of sleep, as in some fits of epilepsy, asthma, and hæmoptoe mentioned in the preceding article. 3. _Hemicraniæ periodus._ Periods of hemicrania. Class IV. 2. 2. 8. The torpor and consequent pain of some membranes on one side of the head, as over one eye, is frequently occasioned by a decaying tooth, and is liable to return every day, or on alternate days at solar or lunar periods. In this case large quantities of the bark will frequently cure the disease, and especially if preceded by venesection and a brisk cathartic; but if the offending tooth can be detected, the most certain cure is its extraction. These partial head-achs are also liable to return at the greater lunar periods, as about once a month. Five drops from a two-ounce phial of a saturated solution of arsenic twice a day for a week or two have been said to prevent the returns of this disease. See a Treatise on Arsenic by Dr. Fowler, of York. Strong errhines have also been recommended. 4. _Epilepsiæ dolorificæ periodus._ Class III. 1. 1. 8. The pain which induces after about an hour the violent convulsions or insanity, which constitute the painful epilepsy, generally observe solar diurnal periods for four or five weeks, and are probably governed by solar and lunar times in respect to their greater periods; for I have observed that the daily paroxysms, unless disturbed by large doses of opium, recur at very nearly the same hour, and after a few weeks the patients have recovered to relapse again at the interval of a few months. But more observations are wanted upon this subject, which might be of great advantage in preventing the attacks of this disease; as much less opium given an hour before its expected daily return will prevent the paroxysm, than is necessary to cure it, after it has commenced. 5. _Convulsionis dolorificæ periodus._ Class III. 1. 1. 6. The pains, which produce these convulsions, are generally left after rheumatism, and come on when the patients are become warm in bed, or have been for a short time asleep, and are therefore perhaps rather to be ascribed to the increasing sensibility of the system during sleep, than to solar diurnal periods, as in Species first and second of this Genus. 6. _Tussis periodicæ periodus._ Periodic cough, Class IV. 2. 1. 9. returns at exact solar periods; that described in Sect. XXXVI. 3. 9. recurred about seven in the afternoon for several weeks, till its periods were disturbed by opium, and then it recurred at eleven at night for about a week, and was then totally destroyed by opium given in very large quantities, after having been previously for a few days omitted. 7. _Catameniæ periodus._ Periods of menstruation. The correspondence of the periods of the catamenia with those of the moon was treated of in Sect. XXXII. 6. and can admit of no more doubt, than that the returns of the tides are governed by lunar influence. But the manner in which this is produced, is less evident; it has commonly been ascribed to some effect of the lunar gravitation on the circulating blood, as mentioned in Sect. XXXII. 6. But it is more analogous to other animal phenomena to suppose that the lunar gravitation immediately affects the solids by its influx or stimulus. Which we believe of the fluid element of heat, in which we are equally immersed; and of the electric fluid, which also surrounds and pervades us. See Sect. XXXVI. 2. 3. If the torpor of the uterine veins, which induces the monthly periods of the catamenia, be governed by the increase of terrene gravitation; that is, by the deficiency of the counter-influence of solar and lunar gravitation; why does not it occur most frequently when the terrene gravitation is the greatest, as about six hours after the new moon, and next to that at about six hours after the full moon? This question has its difficulty; first, if the terrene gravitation be greatest about six hours after the new moon, it must become less and less about the same time every lunar day, till the end of the first quarter, when it will be the least; it must then increase daily till the full. After the full the terrene gravitation must again decrease till the end of the third quarter, when it will again be the least, and must increase again till the new moon; that is, the solar and lunar counter-gravitation is greatest, when those luminaries are vertical, at the new moon, and full moon, and least about six hours afterwards. If it was known, whether more menstruations occur about six hours after the moon is in the zenith or nadir; and in the second and fourth quarters of the moon, than in the first and third; some light would be thrown on this subject; which must in that respect wait for future observations. Secondly, if the lunar influence produces a very small degree of quiescence, suppose of the uterine veins, at first; and if that recurs at certain periods, as of lunar days, or about 25 hours, even with less power to produce quiescence than at first; yet the quiescence will daily increase by the acquired habit acting at the same time, as explained in Sect. XII. 3. 3. till at length so great a degree of quiescence will be induced as to cause the inaction of the veins of the uterus, and consequent venous hæmorrhage. See Sect. XXXII. 6. Class I. 2. 1. 11. IV. 1. 4. 4. See the introduction to this Genus. 8. _Hæmorrhoidis periodus._ The periods of the piles depend on the torpor of the veins of the rectum, and are believed to recur nearly at monthly intervals. See Sect. XXVII. 2. and Class I. 2. 1. 6. 9. _Podagræ periodus._ The periods of gout in some patients recur at annual intervals, as in the case related above in Class IV. 1. 2. 15. in which the gouty paroxysm returned for three successive years on nearly the same day of the month. The commencement of the pain of each paroxysm is generally a few hours after midnight, and may thence either be induced by diurnal solar periods, or by the increasing sensibility during sleep, as mentioned in the first species of this genus. 10. _Erysipelatis periodus._ Some kinds of erysipelas which probably originate from the association of the cutaneous vessels with a diseased liver, occur at monthly periods, like the hæmorrhois or piles; and others at annual periods like the gout; as a torpor of some part I suppose always precedes the erysipelatous inflammation, the periods should accord with the increasing influence of terrene gravitation, as described in the introduction to this Genus, and in Species the seventh of it. Other periods of diseases referable to solar and lunar influence are mentioned in Sect XXXVI. and many others will probably be discovered by future observation. 11. _Febrium periodus._ Periods of fevers. The commencement of the cold fits of intermittent fevers, and the daily exacerbations of other fevers, so regularly recur at diurnal solar or lunar periods, that it is impossible to deny their connection with gravitation; as explained in Sect. XXXVI. 3. Not only these exacerbations of fever, and their remissions, obey the diurnal solar and lunar periods; but the preparatory circumstances, which introduce fevers, or which determine their crisises, appear to be governed by the parts of monthly lunar periods, and of solar annual ones. Thus the variolous fever in the natural small-pox commences on the 14th day, and in the inoculated small-pox on the seventh day. The fever and eruption in the distinct kind take up another quarter of a lunation, and the maturation another quarter. The fever, which is termed canine madness, or hydrophobia, is believed to commence near the new or full moon; and, if the cause is not then great enough to bring on the disease, it seems to acquire some strength, or to lie dormant, till another, or perhaps more powerful lunation calls it into action. In the spring, about three or four years ago, a mad dog very much worried one swine confined in a sty, and bit another in the same sty in a less degree; the former became mad, refused his meat, was much convulsed, and died in about four days; this disease commenced about a month after the bite. The other swine began to be ill about a month after the first, and died in the same manner. * * * * * ORDO III. _Retrograde Associate Motions._ GENUS I. _Catenated with Irritative Motions._ Those retrograde associate motions, the first links of which are catenated with irritative motions, belong to this genus. All the retrograde motions are consequent to debility, or inactivity, of the organ; and therefore properly belong to the genera of decreased actions both in this and the former classes. SPECIES. 1. _Diabætes irritata._ When the absorbents of the intestines are stimulated too strongly by spirit of wine, as in the beginning of drunkenness, the urinary absorbents invert their motions. The same happens from worms in the intestines. In other kinds of diabetes may not the remote cause be the too strong action of the cutaneous absorbents, or of the pulmonary ones? May not in such cases oil externally or internally be of service? or warm bathing for an hour at a time? In hysteric inversions of motion is some other part too much stimulated? or pained from the want of stimulus? 2. _Sudor frigidus in asthmate._ The cause of the paroxysms of humoral asthma is not well understood; I suppose it to be owing to a torpidity or inaction of the absorbents belonging to the pulmonary vessels, as happens probably to other viscera at the commencement of intermittent fevers, and to a consequent accumulation of fluids in them; which at length producing great irritation or uneasy sensation causes the violent efforts to produce the absorption of it. The motions of the cutaneous absorbent vessels by their association with those of the pulmonary ones become retrograde, and effuse upon the skin a fluid, which is said to be viscid, and which adheres in drops. A few days ago I saw a young man of delicate constitution in what was called a fit of the asthma; he had about two months before had a peripneumony, and had been ever since subject to difficult respiration on exertion, with occasional palpitation of his heart. He was now seized about eight at night after some exertion of mind in his business with cold extremities, and difficulty of breathing. He gradually became worse, and in about half an hour, the palpitation of his heart and difficult respiration were very alarming; his whole skin was cold and pale, yet he did not shudder as in cold paroxysm of fever; his tongue from the point to the middle became as cold as his other extremities, with cold breath. He seemed to be in the act of dying, except that his pulse continued equal in time, though very quick. He lost three ounces of blood, and took ten drops of laudanum with musk and salt of hartshorn, and recovered in an hour or two without any cold sweat. There being no cold sweat seems to indicate, that there was no accumulation of serous fluid in the lungs; and that their inactivity, and the coldness of the breath, was owing to the sympathy of the air-cells with some distant part. There was no shuddering produced, because the lungs are not sensible to heat and cold; as any one may observe by going from a warm room into a frosty air, and the contrary. So the steam of hot tea, which scalds the mouth, does not affect the lungs with the sensation of heat. I was induced to believe, that the whole cold fit might be owing to suppuration in some part of the chest; as the general difficulty of breathing seemed to be increased after a few days with pulse of 120, and other signs of empyema. Does the cold sweat, and the occurrence of the fits of asthma after sleep, distinguish the humoral asthma from the cold paroxysm of intermittents, or which attends suppuration, or which precedes inflammation?--I heard a few weeks afterwards, that he spit up much matter at the time he died. 3. _Diabætes a timore._ The motions of the absorbent vessels of the neck of the bladder become inverted by their consent with those of the skin; which are become torpid by their reverse sympathy with the painful ideas of fear, as in Sect. XVI. 8. 1. whence there is a great discharge of pale urine, as in hysteric diseases. The same happens from anxiety, where the painful suspense is continued, even when the degree of fear is small; as in young men about to be examined for a degree at the universities the frequency of making water is very observable. When this anxiety is attended with a sleepless night, the quantity of pale urine is amazingly great in some people, and the micturition very frequent. M. M. Opium. Joy. Consolations of friendship. 4. _Diarrhoea a timore._ The absorbent vessels of the intestines invert their motions by direct consent with the skin; hence many liquid stools as well as much pale urine are liable to accompany continued fear, along with coldness of the skin. The immediate cause of this is the decreased sensorial power of association, which intervenes between the actions of the absorbents of the cold skin, and those of the intestinal absorbents; the motions of the latter become on that account weakened and at length retrograde. The remote cause is the torpor of the vessels of the skin catenated with the pain of fear, as explained in Sect. XVI. 8. 1. The capillaries of the skin consent more generally by direct sympathy with those of the lower intestines, and of the bladder; but by reverse sympathy more generally with those of the stomach and upper intestines. As appears in fevers, where the hot skin accompanies indigestion of the stomach; and in diarrhoeas attended with cold extremities. The remote cause is the torpor of the skin owing to its reverse sympathy with the painful sensual motions, or ideas, of fear; which are now actuated with great energy, so as to deprive the second link of associated motions of their due share of sensorial power. It is also probable, that the pain of fear itself may contribute to exhaust the sensorial power, even when it produces no muscular action. See Class IV. 2. 2. 5. _Pallor et tremor a timore._ A retrograde action of the capillaries of the skin producing paleness, and a torpor of the muscular fibres of the limbs occasioning trembling, are caused by their reverse associations with the ideas or imaginations of fear; which are now actuated with violent energy, and accompanied with great pain. The cause of these associations are explained in Sect XVI. 8. 1. These torpid actions of the capillaries and muscles of the limbs are not caused immediately by the painful sensation of fear; as in that case they would have been increased and not decreased actions, as occurs in anger; where the painful volition increases the actions of the capillaries, exciting a blush and heat of the skin. Whence we may gain some knowledge of what is meant by depressing and exciting passions; the former confiding of ideas attended with pain, which pain occasions no muscular actions, like the pain of cold head-ach; the latter being attended with volitions, and consequent muscular exertions. That is, the pain of fear, and the pain of anger, are produced by the exertion of certain ideas, or motions of certain nerves of sense; in the former case, the painful sensation of fear produces no muscular actions, yet it exhausts or employs so much sensorial power, that the whole system acts more feebly, or becomes retrograde; but some parts of it more so than others, according to their early associations described in Sect. XVI. 8. 1. hence the tremor of the limbs, palpitation of heart, and even syncope. In anger the painful volition produces violent muscular actions; but if previous to these any deliberation occurs, a flushed countenance sometimes, and a red skin, are produced by this superabundance of volition exerted on the arterial system; but at other times the skin becomes pale, and the legs tremble, from the exhaustion or expenditure of the sensorial power by the painful volitions of anger on the organs of sense, as by the painful sensations of fear above mentioned. Where the passion of fear exists in a great degree, it exhausts or expends so much sensorial power, either simply by the pain which attends it, or by the violent and perpetual excitement of the terrific imaginations or ideas, that not only a cold and pale skin, but a retrograde motion of the cutaneous absorbents occurs, and a cold sweat appears upon the whole surface of the body, which probably sometimes increases pulmonary absorption; as in Class II. 1. 6. 4. and as in the cold sweats, which attend the paroxysms of humoral asthma. Hence anxiety, which is a continued pain of fear, so universally debilitates the constitution as to occasion a lingering death; which happens much more frequently than is usually supposed; and these victims of continued anxiety are said to die of a broken heart. Other kinds of paleness are described in Class I. 2. 2. 2. M. M. Opium. Wine. Food. Joy. 6. _Palpitatio cordis a timore._ The palpitation of the heart from fear is owing to the weak action of it, and perhaps sometimes to the retrograde exertion of the ventricules and auricles; because it seems to be affected by its association with the capillaries, the actions of which, with those of the arteries and veins, constitute one great circle of associate motions. Now when the capillaries of the skin become torpid, coldness and paleness succeed; and with these are associated the capillaries of the lungs, whence difficult respiration; and with these the weak and retrograde actions of the heart. At the same time the absorbents of the skin, and of the bladder, and of the intestines, sometimes become retrograde, and regurgitate their contents; as appears by the pale urine in large quantities, which attends hysteric complaints along with this palpitation of the heart; and from the cold sweats, and diarrhoea; all which, as well as the hysteric complaints, are liable to be induced or attended by fear. When fear has still more violently affected the system, there have been instances where syncope, and sudden death, or a total stoppage of the circulation, have succeeded: in these last cases, the pain of fear has employed or exhausted the whole of the sensorial power, so that not only those muscular fibres generally exerted by volition cease to act, whence the patient falls down; and those, which constitute the organs of sense, whence syncope; but lastly those, which perform the vital motions, become deprived of sensorial power, and death ensues. See Class. I. 2. 1. 4. and I. 2. 1. 10. Similar to this in some epileptic fits the patient first suddenly falls down, without even endeavouring to save himself by his hands before the convulsive motions come on. In this case the great exertion of some small part in consequence of great irritation or sensation exhausts the whole sensorial power, which was lodged in the extremities of the locomotive nerves, for a short time, as in syncope; and as soon as these muscles are again supplied, convulsions supervene to relieve the painful sensation. See Class III. 1. 1. 7. 7. _Abortio a timore._ Women miscarry much more frequently from a fright, than from bodily injury. A torpor or retrograde motion of the capillary arteries of the internal uterus is probably the immediate cause of these miscarriages, owing to the association of the actions of those vessels with the capillaries of the skin, which are rendered torpid or retrograde by fear. By this contraction of the uterine arteries, the fine vessels of the placenta, which are inserted into them, are detruded, or otherwise so affected, that the placenta separates at this time from the uterus, and the fetus dies from want of oxygenation. A strong young woman, in the fifth or sixth month of her pregnancy, who has since borne many children, went into her cellar to draw beer; one of the servant boys was hid behind a barrel, and started out to surprise her, believing her to be the maid-servant; she began to flood immediately, and miscarried in a few hours. See Sect. XXXIX. 6. 5. and Class I. 2. 1. 14. 8. _Hysteria a timore._ Some delicate ladies are liable to fall into hysteric fits from sudden fright. The peristaltic motions of the bowels and stomach, and those of the oesophagus, make a part of the great circle of irritative motions with those of the skin, and many other membranes. Hence when the cutaneous vessels become torpid from their reverse sympathy with the painful ideas of fear; these of the bowels, and stomach, and oesophagus, become first torpid by direct sympathy with those of the skin, and then feebly and ineffectually invert the order of their motions, which constitutes a paroxysm of the hysteric disease. See Class I. 3. 1. 10. These hysteric paroxysms are sometimes followed by convulsions, which belong to Class III. as they are exertions to relieve pain; and sometimes by death. See Species 9 of this Genus, and Class I. 2. 1. 4. Indigestion from fear is to be ascribed in the same manner to the torpor of the stomach, owing to its association with the skin. As in Class IV. 1. 2. 5. IV. 2. 1. * * * * * ORDO III. _Retrograde Associate Motions._ GENUS II. _Catenated with Sensitive Motions._ SPECIES. 1. _Nausea idealis._ Nausea from disgustful ideas, as from nauseous stories, or disgustful sights, or smells, or tastes, as well as vomiting from the same causes, consists in the retrograde actions of the lymphatics of the throat, and of the oesophagus, and stomach; which are associated with the disgustful ideas, or sensual motions of sight, or hearing, or smell, or taste; for as these are decreased motions of the lymphatics, or of the oesophagus, or stomach, they cannot immediately be excited by the sensorial power of painful sensation, as in that case they ought to be increased motions. So much sensorial power is employed for a time on the disgustful idea, or expended in the production of inactive pain, which attends it, that the other parts of the associated chain of action, of which this disgustful idea is now become a link, is deprived of their accustomed share; and therefore first stop, and then invert their motions. Owing to deficiency of sensorial power, as explained more at large in Sect. XXXV. 1. 3. 2. _Nausea a conceptu._ The nausea, which pregnant women are so subject to during the first part of gestation, is owing to the reverse sympathy between the uterus and stomach, so that the increased action of the former, excited by the stimulus of the growing embryon, which I believe is sometimes attended with sensation, produces decreased actions of the latter with the disagreeable sensation of sickness with indigestion and consequent acidity. When the fetus acquires so much muscular power as to move its limbs, or to turn itself, which is called quickening, this sickness of pregnancy generally ceases. M. M. Calcined magnesia. Rhubarb. Half a grain of opium twice a day. Recumbent posture on a sofa. 3. _Vomitio vertiginosa._ Sea-sickness, the irritative motions of vision, by which we balance ourselves, and preserve our perpendicularity, are disturbed by the indistinctness of their objects; which is either owing to the similarity of them, or to their distance, or to their apparent or unusual motions. Hence these irritative motions of vision are exerted with greater energy, and are in consequence attended with sensation; which, at first is agreeable, as when children swing on a rope; afterwards the irritative motions of the stomach, and of the absorbent vessels, which open their mouths into it, become inverted by their associations with them by reverse sympathy. For the action of vomiting, as well as the disagreeable sensation of sickness, are shewn to be occasioned by defect of the sensorial power; which in this case is owing to the greater expenditure of it by the sense of vision. On the same account the vomiting, which attends the passage of a stone through the ureter, or from an inflammation of the bowels, or in the commencement of some fevers, is caused by the increased expenditure of the sensorial power by the too great action of some links of the associations of irritative motions; and there being in consequence a deficiency of the quantity required for other links of this great catenation. It must be observed, that the expenditure of sensorial power by the retinas of the eyes is very great; which may be estimated by the perpetual use of those organs during our waking hours, and during most of our sleeping ones; and by the large diameters of the two optic nerves, which are nearly the size of a quill, or equal to some of the principal nerves, which serve the limbs. 4. _Vomitio a calculo in uretere._ The action of vomiting in consequence of the increased or decreased actions of the ureter, when a stone lodges in it. The natural actions of the stomach, which consist of motions subject to intermitted irritations from the fluids, which pass through it, are associated with those of the ureter; and become torpid, and consequently retrograde, by intervals, when the actions of the ureter becomes torpid owing to previous great stimulus from the stone it contains; as appears from the vomiting existing when the pain is least. When the motions of the ureter are thus lessened, the sensorial power of association, which ought to actuate the stomach along with the sensorial power of irritation, ceases to be excited into action; and in consequence the actions of the stomach become less energetic, and in consequence retrograde. For as vomiting is a decreased action of the stomach, as explained in Sect. XXXV. 1. 3. it cannot be supposed to be produced by the pain of gravel in the ureter alone, as it should then be an increased action, not a decreased one. The perpetual vomiting in ileus is caused in like manner by the defective excitement of the sensorial power of association by the bowel, which is torpid during the intervals of pain; and the stomach sympathizes with it. See Enteritis, Class II. 1. 2. 11. Does this symptom of vomiting indicate, whether the disease be above or below the valve of the colon? Does not the softer pulse in some kinds of enteritis depend on the sympathy of the heart and arteries with the sickness of the stomach? See Ileus and Cholera. Hence this sickness, as well as the sickness in some fevers, cannot be esteemed an effort of nature to dislodge any offensive material; but like the sea-sickness described above, and in Sect. XX. 4. is the consequence of the associations of irritative or sensitive motions. See Class I. 1. 3. 9. 5. _Vomitio ab insultu paralytico._ Paralytic affections generally commence with vomiting, the same frequently happens from a violent blow with a stick on the head; this curious connection of the brain and stomach has not been explained; as it resembles the sickness in consequence of vertigo at sea, it would seem to arise from a similar cause, viz. from disturbed irritative or sensitive associations. 6. _Vomitio a titillatione faucium._ If the throat be slightly tickled with a feather, a nausea is produced, that is, an inverted action of the mouths of the lymphatics of the fauces, and by direct sympathy an inverted action of the stomach ensues. As these parts have frequently been stimulated at the same time into pleasurable action by the deglutition of our daily aliment, their actions become strongly associated. And as all the food, we swallow, is either moist originally, or mixed with our moist saliva in the mouth; a feather, which is originally dry, and which in some measure repels the moist saliva, is disagreeable to the touch of the fauces; at the same time this nausea and vomiting cannot be caused by the disagreeable sensation simply, as then they ought to have been increased exertions, and not decreased ones, as shewn in Section XXXV. 1. 3. But the mouths of the lymphatics of the fauces are stimulated by the dry feather into too great action for a time, and become retrograde afterwards by the debility consequent to too great previous stimulus. 7. _Vomitio cute sympathetica._ Vomiting is successfully stopped by the application of a blister on the back in some fevers, where the extremities are cold, and the skin pale. It was stopped by Sydenham by producing a sweat on the skin by covering the head with the bed-clothes. See Class IV. 1. 1. 3. and Suppl. I. 11. 6. * * * * * ORDO III. _Retrograde Associate Motions._ GENUS III. _Catenated with Voluntary Motions._ SPECIES. 1. _Ruminatio._ In the rumination of horned cattle the food is brought up from the first stomach by the retrograde motions of the stomach and oesophagus, which are catenated with the voluntary motions of the abdominal muscles. 2. _Vomitio voluntaria._ Voluntary vomiting. Some human subjects have been said to have obtained this power of voluntary action over the retrograde motions of the stomach and oesophagus, and thus to have been able to empty their stomach at pleasure. See Sect. XXV. 6. This voluntary act of emptying the stomach is possessed by some birds, as the pigeon; who has an organ for secreting milk in its stomach, as Mr. Hunter observed; and softens the food for its young by previously swallowing it; and afterwards putting its bill into theirs returns it into their mouths. See Sect. XXXIX. 4. 8. The pelicans use a stomach, or throat bag, for the purpose of bringing the fish, which they catch in the sea to shore, and then eject them, and eat them at their leisure. See Sect. XVI. 11. And I am well informed of a bitch, who having puppies in a stable at a distance from the house, swallowed the flesh-meat, which was given her, in large pieces, and carrying it immediately to her whelps, brought it up out of her stomach, and laid it down before them. 3. _Eructatio voluntaria._ Voluntary eructation. Some, who have weak digestions, and thence have frequently been induced to eruct the quantity of air discharged from the fermenting aliment in their stomachs, have gradually obtained a power of voluntary eructation, and have been able thus to bring up hogsheads of air from their stomachs, whenever they pleased. This great quantity of air is to be ascribed to the increase of the fermentation of the aliment by drawing off the gas as soon as it is produced. See Sect. XXIII. 4. * * * * * ORDO III. _Retrograde Associate Motions._ GENUS. IV. _Catenated with External Influences._ SPECIES. 1. _Catarrhus periodicus._ Periodical catarrh is not a very uncommon disease; there is a great discharge of a thin saline mucous material from the membranes of the nostrils, and probably from the maxillary and frontal sinuses, which recur once a day at exact solar periods; unless it be disturbed by the exhibition of opium; and resembles the periodic cough mentioned below. See Class I. 3. 2. 1. It is probably owing to the retrograde action of the lymphatics of the membranes affected, and produced immediately by solar influence. 2. _Tussis periodica._ Periodic cough, called nervous cough, and tussis serina. It seems to arise from a periodic retrograde action of the lymphatics of the membrane, which lines the air-cells of the lungs. And the action of coughing, which is violently for an hour or longer, is probably excited by the stimulus of the thin fluid thus produced, as well as by the disagreeable sensation attending membranous inactivity; and resembles periodic catarrh not only in its situation on a mucous membrane, but in the discharge of a thin fluid. As it is partly restrainable, it does not come under the name of convulsion; and as it is not attended with difficult respiration, it cannot be called asthma; it is cured by very large doses of opium, see a case and cure in Sect. XXXVI. 3. 9. see Class IV. 2. 4. 6. and seems immediately to be induced by solar influence. 3. _Histeria a frigore._ Hysteric paroxysms are occasioned by whatever suddenly debilitates the system, as fear, or cold, and perhaps sometimes by external moisture of the air, as all delicate people have their days of greater or less debility, see Class IV. 3. 1. 8. 4. _Nausea pluvialis._ Sickness at the commencement of a rainy season is very common among dogs, who assist themselves by eating the agrostris canina, or dog's grass, and thus empty their stomachs. The same occurs with less frequency to cats, who make use of the same expedient. See Sect. XVI. 11. I have known one person, who from his early years has always been sick at the beginning of wet weather, and still continues so. Is this owing to a sympathy of the mucous membrane of the stomach with the mechanical relaxation of the external cuticle by a moister atmosphere, as is seen in the corrugated cuticle of the hands of washing-women? or does it sympathize with the mucous membrane of the lungs, which must be affected along with the mucus on its surface by the respiration of a moister atmosphere? * * * * * SUPPLEMENT TO CLASS IV. _Sympathetic Theory of Fever._ As fever consists in the increase or diminution of direct or reverse associated motions, whatever may have been the remote cause of them, it properly belongs to the fourth class of diseases; and is introduced at the end of the class, that its great difficulties might receive elucidation from the preceding parts of it. These I shall endeavour to enumerate under the following heads, trusting that the candid reader will discover in these rudiments of the theory of fever a nascent embryon, an infant Hercules, which Time may rear to maturity, and render serviceable to mankind. I. Simple fever of two kinds. II. Compound fever. III. Termination of the cold fit. IV. Return of the cold fit. V. Sensation excited in fever. VI. Circles of associated motions. VII. Alternations of cold and hot fits. VIII. Orgasm of the capillaries. IX. Torpor of the lungs. X. Torpor of the brain. XI. Torpor of the heart and arteries. XII. Torpor of the stomach and intestines. XIII. Case of continued fever explained. XIV. Termination of continued fever. XV. Inflammation excited in fever. XVI. Recapitulation. I. _Simple fever._ 1. When a small part of the cutaneous capillaries with their mucous or perspirative glands are for a short time exposed to a colder medium, as when the hands are immersed in iced water for a minute, these capillary vessels and their glands become torpid or quiescent, owing to the eduction of the stimulus of heat. The skin then becomes pale, because no blood passes through the external capillaries; and appears shrunk, because their sides are collapsed from inactivity, not contracted by spasm; the roots of the hair are left prominent from the seceding or subsiding of the skin around them; and the pain of coldness is produced. In this situation, if the usual degree of warmth be applied, these vessels regain their activity; and having now become more irritable from an accumulation of the sensorial power of irritation during their quiescence, a greater exertion of them follows, with an increased glow of the skin, and another kind of pain, which is called the hot-ach; but no fever, properly so called, is yet produced; as this effect is not universal, nor permanent, nor recurrent. 2. If a greater part of the cutaneous capillaries with their mucous and perspirative glands be exposed for a longer time to cold, the torpor or quiescence becomes extended by direct sympathy to the heart and arteries; which is known by the weakness, and consequent frequency of the pulse in cold fits of fever. This requires to be further explained. The movements of the heart and arteries, and the whole of the circulatory vessels, are in general excited into action by the two sensorial powers of irritation, and of association. The former is excited by stimulus, the latter by the previous actions of a part of the vital circle of motions. In the above situation the capillaries act weakly from defect of irritation, which is caused by deficient stimulus of heat; but the heart and arteries act weakly from defect of association, which is owing to the weak action of the capillaries; which does not now excite the sensorial power of association into action with sufficient energy. After a time, either by the application of warmth, or by the increase of their irritability owing to the accumulation of the sensorial power of irritation during their previous quiescence, the capillary vessels and glands act with greater energy than natural; whence the red colour and heat of the skin. The heart and arteries acquire a greater strength of pulsation, and continue the frequency of it, owing to the accumulation of the sensorial power of association during their previous torpor, and their consequent greater associability; which is now also more strongly excited by the increased actions of the capillaries. And thus a fit of simple fever is produced, which is termed Febris irritativa; and consists of a torpor of the cutaneous capillaries with their mucous and perspirative glands, accompanied with a torpor of the heart and arteries; and afterwards of an increased action of all these vessels, by what is termed direct sympathy. This fever, with strong pulse without inflammation, or febris irritativa, described in Class I. 1. 1. 1. is frequently seen in vernal intermittents, as the orgasm of the heart and arteries is then occasioned by their previous state of torpor; but more rarely I believe exists in the type of continued fever, except there be an evident remission, or approximation to a cold fit; at which time a new accumulation of the sensorial power of association is produced; which afterwards actuates the heart and arteries with unnatural vigour; or unless there be some stimulus perpetually acting on the system so as to induce an increased secretion of sensorial power in the brain, as occurs in slight degrees of intoxication. Since without one or other of these circumstances in continued fevers without inflammation, that is, without the additional sensorial power of sensation being introduced, it seems difficult to account for the production of so great a quantity of sensorial power, as must be necessary to give perpetual increase of action to the whole sanguiferous system. 3. On the contrary, while the cutaneous capillaries with their mucous and perspirative glands acquire an increased irritability, as above, by the accumulation of that sensorial power during their previous quiescence, and thus constitute the hot fit of fever; if the heart and arteries do not acquire any increase of associability, but continue in their state of torpor, another kind of simple fever is produced; which is generally of the continued kind, and is termed Febris inirritativa; which consists of a previous torpor of the capillaries of the skin, and of the heart and arteries by direct sympathy with them; and afterwards of an orgasm or increased action of the capillaries of the skin, with a decreased action, or continued torpor, of the heart and arteries by reverse sympathy with them. This orgasm of the cutaneous capillaries, which appears by the blush and heat of the skin, is at first owing to the accumulation of the sensorial power of irritation during their previous torpid state, as in the febris irritata above described; but which is afterwards supported or continued by the reverse sympathy of these capillaries with the torpid state of the heart and arteries, as will be further explained in article 8 of this Supplement. 4. The renovated activity of the capillaries commences as soon or sooner than that of the heart and arteries after the cold fit of irritative fever; and is not owing to their being forced open by the blood being impelled into them mechanically, by the renovated action of the heart and arteries; for these capillaries of the skin have greater mobility than the heart and arteries, as appears in the sudden blush of shame; which may be owing to their being more liable to perpetual varieties of activity from their exposure to the vicissitudes of atmospheric heat. And because in inirritative fevers, or those with arterial debility, the capillaries acquire increased strength, as is evinced by the heat of the skin, while the pulsations of the heart and arteries remain feeble. 5. It was said above, that the cutaneous capillaries, when they were rendered torpid by exposure to cold, either recovered their activity by the reapplication of external warmth; or by their increased irritability, which is caused by the accumulation of that sensorial power during their quiescence. An example of the former of these may be seen on emerging from a very cold bath; which produces a fit of simple fever; the cold fit, and consequent hot fit, of which may be prolonged by continuing in the bath; which has indeed proved fatal to some weak and delicate people, and to others after having been much exhausted by heat and exercise. See Sect. XXXII. 3. 2. An example of the latter may be taken from going into a bath of about eighty degrees of heat, as into the bath at Buxton, where the bather first feels a chill, and after a minute becomes warm, though he remains in the same medium, owing to the increase of irritability from the accumulation of that sensorial power during the short time, which the chilness continued. 6. Hence simple fevers are of two kinds; first, the febris irritativa, or fever with strong pulse; which consists of a previous torpor of the heart, arteries, and capillaries, and a succeeding orgasm of those vessels. Secondly, the febris inirritativa, or fever with weak pulse, which consists of a previous torpor of the heart, arteries, and capillaries; and of a succeeding orgasm of the capillaries, the torpor of the heart and arteries continuing. But as the frequency of the pulse occurs both in the state of torpor, and in that of orgasm, of the heart and arteries; this constitutes a criterion to distinguish fever from other diseases, which are owing to the torpor of some parts of the system, as paresis, and hemicrania. 7. The reader will please to observe, that where the cutaneous or pulmonary capillaries are mentioned, their mucous and perspirative glands are to be understood as included; but that the absorbents belonging to those systems of vessels, and the commencement of the veins, are not always included; as these are liable to torpor separately, as in anasarca, and petechiæ; or to orgasm, or increased action, as in the exhibition of strong emetics, or in the application of vinegar to the lips; yet he will also please to observe, that an increased or decreased action of these absorbents and veins generally occurs along with that of the capillaries, as appears by the dry skin in hot fits of fever; and from there being generally at the same time no accumulation of venous blood in the cutaneous vessels, which would appear by its purple colour. II. _Compound fever._ 1. When other parts of the system sympathize with this torpor and orgasm of the cutaneous capillaries, and of the heart and arteries; the fever-fit becomes more complicated and dangerous; and this in proportion to the number and consequence of such affected parts. Thus if the lungs become affected, as in going into very cold water, a shortness of breath occurs; which is owing to the collapse or inactivity (not to the active contraction, or spasm), of the pulmonary capillaries; which, as the lungs are not sensible to cold, are not subject to painful sensation, and consequent shuddering, like the skin. In this case after a time the pulmonary capillaries, like the cutaneous ones, act with increased energy; the breathing, which was before quick, and the air thrown out at each respiration in less quantity, and cool to the back of the hand opposed to it, now becomes larger in quantity, and warmer than natural; which however is not accompanied with the sensation of heat in the membrane, which lines the air-vessels of the lungs, as in the skin. 2. One consequence of this increased heat of the breath is the increased evaporation of the mucus on the tongue and nostrils. A viscid material is secreted by these membranes to preserve them moist and supple, for the purposes of the senses of taste and of smell, which are extended beneath their surfaces; this viscid mucus, when the aqueous part of it is evaporated by the increased heat of the respired air, or is absorbed by the too great action of the mucous absorbents, adheres closely on those membranes, and is not without difficulty to be separated from them. This dryness of the tongue and nostrils is a circumstance therefore worthy to be attended to; as it shews the increased action of the pulmonary capillaries, and the consequent increased heat of the expired air; and may thus indicate, when colder air should be admitted to the patient. See Class I. 1. 3. 1. The middle part of the tongue becomes dry sooner, and recovers its moisture later, than the edges of it; because the currents of respired air pass most over the middle part of it. This however is not the case, when the dryness of the tongue is owing only to the increased mucous absorption. When however a frequent cough attends pulmonary inflammation, the edges of the tongue are liable to be as much furred as the middle of it; as during the action of coughing the middle of the tongue is depressed, so as to form half a cylinder, to give a greater aperture for the emission of air from the larynx; and the edges of it become thus as much exposed to the currents of air, as the middle parts of it. 3. When the internal capillaries or glands sympathize with the cutaneous capillaries; or when any of them are previously affected with torpor, and the external or cutaneous capillaries are affected secondarily; other symptoms are produced, which render the paroxysms of fever still more complicate. Thus if the spleen or pancreas are primarily or secondarily affected, so as to be rendered torpid or quiescent, they are liable to become enlarged, and to remain so even after the extinction of the fever-fit. These in some intermittent fevers are perceptible to the hand, and are called ague-cakes; their tumour seems to be owing to the permanent torpor of the absorbent system, the secerning vessels continuing to act some time afterwards. If the secretory vessels of the liver are affected first with torpor, and afterwards with orgasm, a greater secretion of bile is produced, which sometimes causes a diarrhoea. If a torpor of the kidneys, and of the absorbents of the bladder occurs, either primarily, or by sympathy with the cutaneous capillaries, the urine is in small quantity and pale, as explained in Class I. 2. 2. 5.; and if these secretory vessels of the kidneys, and the absorbents of the bladder act more strongly than natural afterwards by their increased irritability or associability, the urine becomes in larger quantity, and deeper coloured, or deposits its earthy parts, as in Class I. 1. 2. 4. which has been esteemed a favourable circumstance. But if the urine be in small quantity, and no sediment appears in it, after the hot fit is over; it shews, that the secerning vessels of the kidneys and the absorbent vessels of the bladder have not regained the whole of their activity, and thence indicates a greater tendency to a return of the cold fit. 4. When the stomach is affected with torpor either primarily; or secondarily by its sympathy with the cutaneous capillaries; or with some internal viscus; sickness occurs, with a total want of appetite to any thing solid; vomiting then supervenes, which may often be relieved by a blister on the skin, if the skin be cool and pale; but not if it be hot and flushed. The intestines cease to perform their office of absorption from a similar torpor; and a diarrhoea supervenes owing to the acrimony of their putrid, or of their acid contents. The loose undigested or fetid stools indicate the inability of the intestines to perform their proper office; as the mucus and gastric acid, which are vomited up, does that of the stomach; this torpor of the stomach is liable to continue after the cold paroxysm ceases, and to convert intermittent fevers into continued ones by its direct sympathy with the heart and arteries. See article 10 of this Supplement. 5. If the meninges of the brain sympathize with other torpid parts, or are primarily affected, delirium, stupor, and perhaps hydrocephalus internus occur, see Class II. 1. 7. 1. and I. 2. 5. 10; and sometimes the pulse becomes slow, producing paresis instead of fever. But if the membranes, which cover the muscles about the head, or of the pericranium, become torpid by their sympathy with other torpid parts, or are primarily affected, a head-ach supervenes; which however generally ceases with the cold paroxysm of fever. For as when the sensorial power of volition is exhausted by labour, a few hours, or half a solar day, passed in sleep recruits the system by accumulation of this sensorial power; so when the sensorial power of irritation is exhausted, one or two solar or lunar days of rest or quiescence of the affected part will generally restore its action by accumulation of irritability, and consequent increase of association, as in hemicrania, Class IV. 2. 2. 8. But when the heart and arteries become torpid, either primarily, or by their sympathy with the stomach, this accumulation of the sensorial power of irritation can take place but slowly; _as to rest is death_! This explains the cause of the duration of fevers with weak pulse, which continue a quarter, or half, or three quarters, or a whole lunation, or still longer, before sufficient accumulation of irritability can be produced to restore their natural strength of action. 6. If the absorbent vessels, which are spread around the neck of the bladder, become torpid by their direct sympathy with the absorbents of the skin in cold fits of fever; the urine, which is poured into the bladder in but small quantity from the torpid kidneys, has nevertheless none of its aqueous saline part reabsorbed; and this saline part stimulates the bladder to empty itself frequently, though the urine is in small quantity. Which is not therefore owing to any supposed spasm of the bladder, for the action of it in excluding the urine is weak, and as much controlable by the will as in ordinary micturition. 7. If the beginnings or absorbent mouths of the venous system remain torpid, petechiæ or vibices are produced in fevers, similar to those which are seen in scurvy without fever. If the skin was frequently moistened for an hour, and at the same time exposed to the common air, or to oxygen gas, it might contribute to turn the black colour of these points of extravasated blood into scarlet, and thus by increasing its stimulus facilitate its reabsorption? For oxygen gas penetrates moist animal membranes though not dry ones, as in the lungs during respiration. 8. When the sensorial power of sensation is introduced into the arterial system, other kinds of compound fevers are produced, which will be spoken of in their place. III. _Termination of the cold Fit._ 1. If all the parts, which were affected with torpor, regain their irritability, and associability, the cold paroxysm of fever ceases; but as some of the parts affected were previously accustomed to incessant action, as the heart and arteries, and others only to intermitted action, as the stomach and intestines; and as those, which are subjected during health to perpetual action, accumulate sensorial power faster, when their motions are impeded, than those which are subjected to intermitted action; it happens, that some of the parts, which were affected with torpor during the cold fit, recover their irritability or associability sooner than others, and more perfectly, or acquire a greater quantity of them than natural; as appears by the partial heat and flushings previous to the general hot fit. Hence if all the parts, which were previously torpid, regain their due degree of irritability, or of associability, the disease is removed, and health restored. If some or all of them acquire more than their natural degree of these sensorial powers; increased actions, and consequent increased secretions, and greater heat occur, and constitute the hot fit of fever. If after this hot fit of fever all the parts, which had acquired too great irritability, or associability, regain their natural degree of it; the disease is removed, and health restored. But if some of these parts do not regain their natural degree of these sensorial powers, the actions of those parts remain imperfect, and are more or less injurious to the system, according to the importance of their functions. 2. Thus if a torpor of the heart and arteries remains; the quick pulse without strength, which began in the cold fit, persists; and a continued fever is produced. If the torpor of the stomach and intestines remains, which are known by sickness and undigested stools, the fever is liable to be of considerable length and danger; the same if the kidnies and absorbent system retain some degree of torpor, as is shewn by the pale urine in not unusual quantity. If part of the absorbent system remains torpid, as the absorbent vessels of the spleen, a tumour of that viscus occurs, which may be felt by the hand; the same sometimes happens to the liver; and these from their tendency to more complete torpor are afterwards liable to give occasion to a return of the cold fit. If the cellular absorbents do not completely recover their activity, a pale and bloated countenance with swelled legs mark their want of action. 3. As the termination of the cold fit is owing to the accumulation of the sensorial power of irritation and of association during the previous quiescence of the system; and as those parts, which are in perpetual action during health, are more subject to this accumulation during their torpor, or quiescence; one should have imagined, that the heart and arteries would acquire this accumulation of sensorial power sooner or in greater degree than other parts. This indeed so happens, where the pulse is previously strong, as in febris irritativa; or where another sensorial power, as that of sensation, is exerted on the arterial system, as in inflammations. The heart and arteries in these cases soon recover from their torpor, and are exerted with great violence. Many other parts of the system subject to perpetual motion in health may rest for a time without much inconvenience to the whole; as when the fingers of some people become cold and pale; and during this complete rest great accumulation of irritability may be produced, But where the heart and arteries are previously feeble, they cannot much diminish their actions, and certainly cannot rest entirely, for that would be death; and therefore in this case their accumulation of the sensorial power of irritation or of association is slowly produced, and a long fever supervenes in consequence; or sudden death, as frequently happens, terminates the cold fit. Whence it appears, that in fevers with weak pulse, if the action of the heart, arteries, and capillaries could be diminished, or stopped for a short time without occasioning the death of the patient, as happens in cold bathing, or to persons apparently drowned, that a great accumulation of the sensorial powers of irritation or of association might soon be produced, and the pulse become stronger, and consequently slower, and the fever cease. Hence cold ablution may be of service in fevers with weak pulse, by preventing the expenditure and producing accumulation of the sensorial power of irritation or association. Stupor may be useful on the same account. Could a centrifugal swing be serviceable for this purpose, either by placing the head or the feet in the outward part of the circle, as described in Art. 15. 7. of this Supplement? IV. _Return of the cold Fit._ 1. If the increased action of the cutaneous and pulmonary capillaries, and of the heart and arteries, in febris irritativa continues long and with violence, a proportional expenditure or exhaustion of sensorial power occurs; which by its tendency to induce torpor of some part, or of the whole, brings on a return of the cold fit. 2. Another cause which contributes to induce torpor of the whole system by the sympathy of its parts with each other, is the remaining torpor of some viscus; which after the last cold paroxysm had not recovered itself, as of the spleen, liver, kidnies, or of the stomach and intestines, or absorbent vessels, as above mentioned. 3. Other causes are the deficiency of the natural stimuli, as hunger, thirst, and want of fresh air. Other causes are great fatigue, want of rest, fear, grief, or anxiety of mind. And lastly, the influence of external ethereal fluids, as the defect of external heat, and of solar or lunar gravitation. Of the latter the return of the paroxysms of continued fevers about six o'clock in the evening, when the solar gravitation is the least, affords an example of the influence of it; and the usual periods of intermittents, whether quotidian, tertian, or quartan, which so regularly obey solar or lunar days, afford instances of the influence of those luminaries on these kinds of fevers. 4. If the tendency to torpor of some viscus is considerable, this will be increased at the time, when the terrene gravitation is greatest, as explained in the introduction to Class IV. 2. 4. and may either produce a cold paroxysm of quotidian fever; or it may not yet be sufficient in quantity for that purpose, but may nevertheless become greater, and continue so till the next period of the greatest terrene gravitation, and may then either produce a paroxysm of tertian fever; or may still become greater, and continue so till the next period of greatest terrene gravitation, and then produce a paroxysm of quartan ague. And lastly, the periodical times of these paroxysms may exceed, or fall short of, the time of greatest diurnal terrene gravitation according to the time of day, or period of the moon, in which the first fit began; that is, whether the diurnal terrene gravitation was then in an increasing or decreasing state. V. _Sensation excited in Fever._ 1. A curious observation is related by Dr. Fordyce in his Tract on Simple fever, page 168. He asserts, that those people, who have been confined some time in a very warm atmosphere, as of 120 or 130 degrees of heat, do not feel cold, nor are subject to paleness of their skins, on coming into a temperature of 30 or 40 degrees; which would produce great paleness and painful sensation of coldness in those, who had been some time confined in an atmosphere of only 86 or 90 degrees. Analogous to this, an observing friend of mine assured me, that once having sat up to a very late hour with three or four very ingenious and humorous companions, and drank a considerable quantity of wine; both contrary to his usual habits of life; and being obliged to rise early, and to ride a long journey on the next day; he expected to have found himself weak and soon fatigued; but on the contrary he performed his journey with unusual ease and alacrity; and frequently laughed, as he rode, at the wit of the preceding evening. In both these cases a degree of pain or pleasure actuated the system; and thus a sensorial power, that of sensation, was superadded to that of irritation, or volition. See Sect. XXXIV. 2. 6. 2. Similar to this, when the energetic exertions of some parts of the system in the hot fit of fever arise to a certain excess, a degree of sensation is produced; as of heat, which particularly increases the actions of the cutaneous vessels, which are more liable to be excited by this stimulus. When this additional sensorial power of sensation exists to a greater degree, the pulse, which was before full, now becomes hard, owing to the inflammation of the vasa vasorum, or coats of the arteries. In these cases, whether there is any topical inflammation or not, the fever ceases to intermit; but nevertheless there are daily remissions and exacerbations of it; which recur for the most part about six in the evening, when the solar gravitation is the least, as mentioned in Sect. XXXVI. 3. 7. 3. Thus the introduction of another sensorial power, that of sensation, converts an intermittent fever into a continued one. If it be attended with strong pulse, it is termed febris sensitiva irritata, or pyrexia, or inflammation; if with a weak pulse, it is termed febris sensitiva inirritata, or typhus gravior, or malignant fever. The seat of the inflammation is in the glandular or capillary system, as it consists in the secretion of new fluids, or new fibres, which form new vessels, as they harden, like the silk of the silk-worm. See Art. 15. of this Supplement. VI. _Circles of irritative Associate Motions._ 1. There are some associate motions, which are perpetually proceeding in our waking hours, and are catenated by their first link, or in some subsequent parts of the chain, with the stimuli or the influence of external things; which we shall here enumerate, as they contribute to the knowledge of fever. Of these are the irritative ideas, or sensual motions of the organs of sense, and the muscular motions associated with them; which, when the chain is disturbed or interrupted, excite the sensorial power of sensation, and proceed in confusion. Thus if the irritative ideas of sight are disturbed, the paralactic motions of objects, which in general are unperceived, become sensible to us; and the locomotive muscles associated with them, which ought to preserve the body erect, stagger from this decrease or interruption of the sensorial power of association; and vertigo is produced. When the irritative sensual motions, or ideas, belonging to one sense are increased or diminished, the irritative sensual motions, or ideas, of the other senses are liable to become disturbed by their general catenations; whence occur noises in the ears, bad tastes in the mouth, bad odours, and numbness or tingling of the limbs, as a greater or less number of senses are affected. These constitute concomitant circles of disturbed irritative ideas; or make a part of the great circle of irritative ideas, or motions of the organs of sense; and when thus disturbed occasion many kinds of hallucination of our other senses, or attend on the vertigo of vision. 2. Another great circle of irritative associated motions consists of those of the alimentary canal; which are catenated with stimuli or with influences external to the system, but continue to be exerted in our sleeping as well as in our waking hours. When these associations of motion are disturbed by the too great or too small stimulus of the food taken into the stomach, or by the too great excess or deprivation of heat, or by indigestible substances, or by torpor or orgasm occasioned by their association with other parts, various diseases are induced under the names of apepsia, hypochondriasis, hysteria, diarrhoea, cholera, ileus, nephritis, fever. 3. A third circle of irritative associate motions consists of those of the absorbent system; which may be divided into two, the lacteals, and the lymphatics. When the stomach and intestines are recently filled with food and fluid, the lacteal system is stimulated into great action; at the same time the cellular, cutaneous, and pulmonary lymphatics act with less energy; because less fluid is then wanted from those branches, and because more sensorial power is expended by the lacteal branch. On this account these two systems of absorbents are liable to act by reverse sympathy; hence pale urine is made after a full dinner, as less of the aqueous part of it is imbibed by the urinary lymphatics; and hence the water in anasarca of the lungs and limbs is speedily absorbed, when the actions of the lacteals of the stomach or intestines are weakened or inverted by the exhibition of those drugs, which produce nausea, or by violent vomiting, or violent cathartics. Hence in diabetes the lacteal system acts strongly, at the same time that the urinary lymphatics invert their motions, and transmit the chyle into the bladder; and in diarrhoea from crapula, or too great a quantity of food and fluid taken at a time, the lacteals act strongly, and absorb chyle or fluids from the stomach and upper intestines; while the lymphatics of the lower intestines revert their motions, and transmit this over-repletion into the lower intestines, and thus produce diarrhoea; which accounts for the speedy operation of some cathartic drugs, when much fluid is taken along with them. 4. Other circles of irritative associate motions of great importance are those of the secerning system; of these are the motions of the larger congeries of glands, which form the liver, spleen, pancreas, gastric glands, kidneys, salivary glands, and many others; some of which act by direct and others by reverse sympathy with each other. Thus when the gastric glands act most powerfully, as when the stomach is filled with food, the kidneys act with less energy; as is shewn by the small secretion of urine for the first hour or two after dinner; which reverse sympathy is occasioned by the greater expenditure of sensorial power on the gastric glands, and to the newly absorbed fluids not yet being sufficiently animalized, or otherwise prepared, to stimulate the secretory vessels of the kidneys. But those very extensive glands, which secrete the perspirable matter of the skin and lungs, with the mucus, which lubricates all the internal cells and cavities of the body, claim our particular attention. These glands, as well as all the others, proceed from the capillary vessels, which unite the arteries with the veins, and are not properly a part of them; the mucous and perspirative glands, which arise from the cutaneous and pulmonary capillaries, are associated by direct sympathy; as appears from immersion in the cold bath, which is therefore attended with a temporary difficult respiration; while those from the capillaries of the stomach and heart and arteries are more generally associated by reverse sympathy with those of the cutaneous capillaries; as appears in fevers with weak pulse and indigestion, and at the same time with a hot and dry skin. The disturbed actions of this circle of the associate motions of the secerning system, when the sensorial power of sensation is added to that of irritation, frequently produces inflammation, which consists in the secretion of new fluids or new vessels. Nevertheless, if these disturbed actions be of the torpid kind, the pain, which attends them, is seldom productive of inflammation, as in hemicrania; but is liable to excite voluntary actions, and thus to expend much sensorial power, as in the shuddering in cold fits of fever, or in convulsions; or lastly the pain itself, which attends torpid actions, is liable to expend or exhaust much sensorial power without producing any increased actions; whence the low pulse, and cold extremities, which usually attend hemicrania; and hence when inert, or inactive sensation attends one link of associated action, the succeeding link is generally rendered torpid, as a coldness of the cheek attends tooth-ach. 5. A fifth important circle of irritative motions is that of the sanguiferous system, in which the capillary vessels are to be included, which unite the arterial and venous systems, both pulmonary and aortal. The disturbed action of this system of the heart and arteries, and capillaries, constitute simple fever; to which may be added, that the secerning and absorbent vessels appending to the capillaries, and the bibulous mouths of the veins, are in some measure at the same time generally affected. 6. Now, though the links of each of these circles of irritative motions are more strictly associated together, yet are they in greater or less degree associated or catenated with each other by direct or reverse sympathy. Thus the sickness, or inverted irritative motions of the stomach, are associated or catenated with the disturbed irritative ideas, or sensual motions, in vertigo; as in sea-sickness. This sickness of the stomach is also associated or catenated with the torpor of the heart and arteries by direct sympathy, and with the capillaries and absorbents by reverse sympathy; and are thus all of them liable occasionally to be disturbed, when one of them is diseased; and constitute the great variety of the kinds or symptoms of fevers. VII. _Alternation of the cold and hot Fits._ 1. When any cause occurs, which diminishes to a certain degree the supply of sensorial power in respect to the whole system; as suppose a temporary inexertion of the brain; what happens? First, those motions are exerted with less energy, which are not immediately necessary to life, as the locomotive muscles; and those ideas, which are generally excited by volition; at the same time this deficiency of voluntary motion is different from that which occurs in sleep; as in that the movements of the arterial system are increased in energy though not in frequency. Next, the motions of the alimentary canal become performed with less energy, or cease altogether; and a total want of appetite to solid food occurs, or sickness, or a diarrhoea occasioned by the indigested aliment. Then the absorbent vessels cease to act with their due energy; whence thirst, and pale urine, though in small quantities. Fourthly, the secerning vessels become affected by the general diminution of sensorial power; whence all the secreted fluids are produced in less quantity. And lastly, the sanguiferous canals feel the general torpor; the pulsations of the heart and arteries become feeble, and consequently quick; and the capillaries of the skin become inactive, acquire less blood from the arteries, and are consequently paler and shrunk. In this last circumstance of the torpor of the sanguiferous system consists inirritative fever; as all the others are rather accidental or concomitant symptoms, and not essential ones; as fewer or more of them may be present, or may exist with a greater or less degree of inactivity. 2. Now as the capillaries of the skin are exposed to greater varieties of heat and cold, than the heart and arteries, they are supposed to be more mobile, that is, more susceptible of torpor or exertion, or to inflammation, by external stimuli or influences, than the other parts of the sanguiferous system; and as the skin is more sensible to the presence of heat, than the internal parts of the body, the commencement of the cold paroxysms of fever generally either first exists in, or is first perceived by, the coldness and paleness of the skin; and the commencement of the hot fits by the heat and redness of it. 3. The accumulation of sensorial power occurs in these organs soonest, and in greatest quantity, during their quiescence, which were most perpetually in action during health; hence those parts of the system soonest recover from torpor in intermittent fever, and soonest fall into the contrary extreme of increased activity; as the sanguiferous system of the heart and arteries and capillaries. But of these the capillaries seem first to acquire a renovation of their action, as the heat of the skin becomes first renewed, as well as increased beyond its natural quantity, and this in some parts sooner than in others; which quantity of heat is however not to be estimated simply by the rise of the mercury in the thermometer, but also by the quantity carried away into the atmosphere, or diffused amongst other bodies in a given time; as more heat passes through water, which boils vehemently, than when it boils gently, though the rise of the thermometer in both cases continues the same. This fact may be known by boiling an egg in water, the white of which coagulates in much less time, if the water boils vehemently, than if it boils moderately, though the sensible heat of the water is the same in both cases. Another cause, which induces the cutaneous capillaries to renew their actions sooner than the heart and arteries after immersion in the cold bath, is, that their torpor was occasioned by defect of irritation; whereas that of the heart and arteries was occasioned by defect of association; which defect of association was owing to the decreased actions of the capillaries, and is now again excited by their renewed action; which excitement must therefore be subsequent to that increased action of the capillaries; and in consequence the increased action of the heart and arteries at the commencement of the hot fit of some fevers is subsequent to the increased action of the cutaneous capillaries. There is, however, in this case an accumulation of the sensorial power of association in the heart and arteries, which must contribute to increase their orgasm in the hot fit, as well as the increased excitement of it by the increased action of the capillaries. 4. Now this increased action of the system, during the hot fit, by exhausting the sensorial powers of irritation and association, contributes to induce a renewal of the cold paroxysm; as the accumulation of those sensorial powers in the cold fit produces the increased actions of the hot fit; which two states of the system reciprocally induce each other by a kind of libration, or a plus and minus, of the sensorial powers of irritation and association. If the exhaustion of sensorial power during the hot fit of fever only reduces the quantity of irritability and associability to its natural standard, the fever is cured, not being liable to return. If the quantity of these sensorial powers be reduced only so much, as not to produce a second cold fit during the present quantity of external stimuli or influences; yet it may be so far reduced, that a very small subtraction of stimulus, or of influence, may again induce a cold fit; such as the coldness of the night-air, or the diminution of solar or lunar gravitation, as in intermittent fevers. 5. Another cause of the renovation of the cold fits of fever is from some parts of the system not having completely recovered from the former cold paroxysm; as happens to the spleen, liver, or other internal viscus; which sometimes remains tumid, and either occasions a return of the cold fit by direct sympathy with other parts of the body, or by its own want of action causes a diminution of the general quantity of heat, and thus facilitates the renovation of the torpor of the whole system, and gives cause to intermittent fevers catenated with lunar or solar influence. VIII. _Orgasm of the Capillaries._ As the remaining torpor of some less essential part of the system, as of the spleen, when the hot fit ceases, produces after one, two, or three days a return of cold fit by direct sympathy with the cutaneous capillaries, when joined with some other cause of torpor, as the defect of solar or lunar influences, or the exposure to cold or hunger, and thus gives origin to intermittent fever; so the remaining torpor of some more essential parts of the system, as of the stomach and intestines, is probably the cause of the immediate recurrence of the cold paroxysm, at the time the hot one ceases, by their direct sympathy with the cutaneous capillaries, without the assistance of any other cause of torpor; and thus produces remittent fever. And lastly the remaining torpor of some still more essential parts of the system, as the heart and arteries, after the hot fit ought to cease, is liable by reverse sympathy with the cutaneous capillaries to continue their orgasm, and thus to render a fever continual, which would otherwise remit or intermit. Many difficulties here occur, which we shall endeavour to throw some light upon, and leave to future investigation; observing only that difficulties were to be expected, otherwise fevers would long since have been understood, as they have employed the unremitted attention of the physicians of all ages of the world. 1. Why do the same parts of successive trains of action sometimes affect each other by direct, and sometimes by reverse sympathy?--1st, When any irritative motion ceases, or becomes torpid, which was before in perpetual action; it is either deprived of its usual stimulus, and thence the sensorial power of irritation is not excited; or it has been previously too much stimulated, and the sensorial power has been thus exhausted. In the former case an accumulation of sensorial power soon occurs, which is excitable by a renewal of the stimulus; as when the fingers, which have been immersed some time in snow, are again exposed to the usual warmth of a room. Or, secondly, the sensorial power of irritation becomes so much accumulated, that the motions, which were torpid, are now performed by less stimulus than natural; as appears by the warmth, which soon occurs after the first chill in going into frosty air, or into the bath at Buxton, which is about eighty degrees of heat. Or, lastly, this accumulation of the sensorial power of irritation so far abounds, that it increases the action of the next link of the associated train or tribe of motions; thus on exposing the skin to cold air, as in walking out in a frosty morning, the actions of the stomach are increased, and digestion strengthened. But where the torpor of some irritative motion is owing to the previous exhaustion of the sensorial power of irritation by too great stimulus, the restoration of it occurs either not at all, or much more slowly than in the former instances; thus after intoxication the stomach is very slow in recovering its due quantity of the sensorial power of irritation, and never shews any accumulation of it. 2. When an associate motion, as described in the introduction to Class IV. 1. 1. acts with less energy, the sensorial power of association is either not sufficiently excited by the preceding fibrous motions; or it has been expended or exhausted by the too violent actions of the preceding fibrous motions. In the former case there occurs an accumulation of the sensorial power of association; exactly as, where the usual stimulus is withdrawn, there occurs an accumulation of the sensorial power of irritation. Thus when the actions of the capillaries of the skin are diminished by immersion in cold water, the capillaries of the lungs are rendered torpid by the want of the excitement of the sensorial power of association, owing to the lessened actions of the previous fibrous motions, namely, of those of the skin. Nevertheless as soon as the capillaries of the skin regain their increased activity by the accumulation of the sensorial power of irritation, these capillaries of the lungs act with greater energy also owing to their accumulated sensorial power of association. These are instances of direct sympathy, and constitute the cold and hot paroxysms of intermittent fever; or the first paroxysm of a continued one. 3. When the first link of a train of associated motions, which is subject to perpetual action, becomes a considerable time torpid for want of being excited by the previous exertions of the irritative motions, with which it is catenated; the sensorial power of association becomes accumulated in so great a degree as to affect the second link of the train of associated motions, and to excite it into stronger action. Thus when the stomach is rendered torpid by contagious matter swallowed into it mixed with the saliva, the heart and arteries act more feebly; because the sensorial power of association, which used to be excited by the fibrous motions of the stomach, is not now excited; and in consequence the motions of the heart and arteries act only by the sensorial power of irritation, which is excited by the stimulus of the blood. But during this torpor of the stomach, and less action of the heart and arteries, so great an accumulation of the sensorial powers of irritation and of association occurs, that it adds to the action of the next link of this vital circle of actions, that is, to that of the cutaneous capillaries. Whence in this situation the torpor of the stomach occasions a diminished action of the heart and arteries by direct sympathy, and may be said to occasion an increased one of the cutaneous capillaries by reverse sympathy; which constitute continued fever with weak pulse. Nor is this increased action of the capillaries in consequence of the decreased action of the heart and arteries, as in fevers with weak pulse, a single fact in the animal economy; though it exists in this case in the greatest degree or duration, because the heart and arteries are perpetually in greater action than any other part of the system. But a similar circumstance occurs, when the stomach is rendered inactive by defective excitement of the sensorial power of association, as in sea-sickness, or in nephritis. In these cases the sensorial power of association becomes much accumulated in the stomach, and seems by its superabundance to excite the absorbent system, which is so nearly connected with it, into great increase of action; as is known by the great quantity frequently in these situations rejected by vomit, which could not otherways be supplied. It is probable the increase of digestion by walking in frosty air, with many other animal facts, may by future observations be found to be dependent on this principle, as well as the increased action of the capillaries in continued fevers with weak pulse. Whereas in continued fever with strong pulse, which may perhaps occur sometimes on the first day even of the plague, the stomach with the heart and arteries and the capillaries act by direct sympathy; that is, the stomach is excited into stronger action by increased irritation owing to the stimulus of contagious matter; these stronger irritative motions of the stomach excite a greater quantity of the sensorial power of association, which then actuates the heart and arteries with greater energy, as these are catenated with the stomach; and in the same manner the increased actions of the heart and arteries excite a greater quantity of the sensorial power of association, which actuates the cutaneous capillaries with increase of energy. See Class IV. 1. 1. 4. I shall dwell a little longer on this intricate subject. The commencement of fever-fits is known by the inactivity of the cutaneous capillaries, which inactivity is observable by the paleness and coldness of the skin, and also by the pain of coldness, which attends it. There is nevertheless in most cases, except those which are owing to exposure to external cold, a torpor of the capillaries of some internal viscus preceding this inactivity of the cutaneous capillaries; which is known, by the tumour or hardness of the viscus, or by an aching pain of it. The capillaries of the lungs are at the same time rendered inactive or torpid, as appears by the difficulty of breathing, and coldness of the breath in cold fits of fever, and in going into the cold bath; but the lungs are not affected with the pain either of coldness or of torpor. One cause of this synchronous or successive inactivity of the cutaneous capillaries, in consequence of the previous torpor of some internal viscus, may be owing to the deficiency of heat; which must occur, when any part becomes inactive; because the secretions of that part cease or are lessened, and the quantity of heat of it in consequence. But the principal cause of it I suppose to be owing to the defect of the sensorial power of association; which power of association is excited by some previous or concomitant motions of the parts of every great circle of actions. This appears on going into the cold bath, because the shortness of breath instantly occurs, sooner than one can conceive the diminution of the heat of the skin could affect the lungs by the want of its stimulus; but not sooner than the defect of the sensorial power of association could affect them; because this must cease to be excited into action on the instant that the cutaneous capillaries cease to act; whence in the first moment of contact of the cold water the cutaneous capillaries cease to act from defect of irritation; which is caused by defect of the stimulus of heat; and in the second moment the capillaries of the lungs cease to act from the defect of association; which is caused by the defect of the motions of the cutaneous capillaries. Thus the universal torpor in the cold paroxysm of fever is an example of direct sympathy, though occasioned in part by defect of irritation, and in part by defect of association. 5. Thus in walking out in a frosty morning the skin is cooled by the contact of the cold air, whence the actions of its capillaries are diminished for want of their usual stimulus of heat to excite a sufficient quantity of the sensorial power of irritation. Hence there is at first a saving of sensorial power of irritation for the purpose of actuating the other parts of the system with greater energy. Secondly the sensorial power of association, which used to be excited by the motions of the cutaneous capillaries, is now not so powerfully excited; and in consequence the parts, which constitute the next links of the circles of associated motions, are for a time actuated with less energy, and a temporary general chillness succeeds; which is so far similar to the cold fit of intermittent fever. In this situation there is a curious circumstance occurs, which merits peculiar attention: after a short time, though the external skin continues cool by its exposure to the cold air, and the actions of its capillaries are consequently diminished, yet the capillaries of the stomach act with greater energy; as is known by increased digestion and consequent hunger. This is to be ascribed to the accumulation of the sensorial power of irritation, which now excites by its superabundance, or overflowing, as it were, the stomach into increased action; though it is at the same time excited less powerfully than usual by the sensorial power of association. Thus the accumulation of the sensorial power of irritation in the vessels of the skin increases in this case the action of the stomach, in the same manner as an accumulation of the sensorial power of association in the heart and arteries in fevers with weak pulse increases the action of the capillaries. If nevertheless the coldness of the skin be too long continued, or exists in too great a degree, so as in some measure to impair the life of the part, no further accumulation of the sensorial power of irritation occurs; and in consequence the actions of the stomach become less than natural by the defect of the sensorial power of association; which has ceased to be excited by the want of action of the cutaneous capillaries. Whence continued coldness of the feet is accompanied with indigestion and heartburn. See Class IV. 2. 1. 6. 6. Similar to this when the actions of the stomach are rendered torpid by the previous stimulus of a violent emetic, and its motions become retrograde in consequence, a great quantity of sensorial power is exerted on the lymphatics of the lungs, and other parts of the body; which excites them into greater direct action, as is evinced by the exhibition of digitalis in anasarca. In this situation I suppose the emetic drug stimulates the muscular fibres of the stomach into too great action; and that in consequence a great torpor soon succeeds; and that this inaction of the muscular parts of the stomach is not followed by much accumulation of the sensorial power of irritation; because that sensorial power is in great measure exhausted by the previous excessive stimulus. But the lymphatics of the stomach have their actions lessened by defect of the sensorial power of association, which is not now excited into action, owing to the lessened motions of the muscular parts of it, with which the lymphatics are associated. The sensorial power of association becomes therefore accumulated in these lymphatics of the stomach, because it is not excited into action; exactly as the power of irritation becomes accumulated in the hand, when immersed in snow; and this accumulated sensorial power of association excites the lymphatic of the lungs and of other parts, which are most nearly associated with those of the stomach, into more energetic actions. Thus the muscular fibres of the stomach act with the lymphatics of that organ in direct sympathy; and the lymphatics of the stomach act in reverse sympathy with those of the lungs and of other parts of the body; the former of which is caused by defect of the excitement of the sensorial power of association, and the latter by the accumulation of it. Besides the efficient cause, as above explained, the final cause, or convenience, of these organic actions are worthy our attention. In this case of an acrid drug swallowed into the stomach the reverted actions of the muscular fibres of the stomach tend to eject its enemy; the reverted actions of its lymphatics pour a great quantity of fluids into the stomach for the purpose of diluting or washing off the noxious drug; and the increased actions of the other lymphatics supply these retrograde ones of the stomach with an inconceivable supply of fluids, as is seen in Ileus and Cholera. 7. The inquisitive reader will excuse my continuing this subject, though perhaps with some repetitions, as it envelopes the very essence of fever. When the first link of a train of actions is excited by excessive stimulus, or excessive irritability, and thus acts with unusual energy by the increased quantity of irritation, these increased motions excite a greater quantity of the sensorial power of association, which causes increased motions in the second link, which is catenated with the first; and then the excessive action of this second link excites also a greater quantity of the sensorial power of association, which increases the motions of the third link of this chain of association, and thus the increase of the stimulus on the irritative motions, to which the chain of association is catenated, increases the action of the whole chain or circle of associated motions. After a time the irritative motions become torpid by expenditure of the sensorial power of irritation, and then the power of association also becomes less exerted, both because it has been in part exhausted by too great action, and is now less excited by the lessened action of the irritative motions, which used to excite it. These are both instances of direct sympathy, and frequently constitute the cold and hot fit of intermittents. But though the accumulation of the sensorial power of irritation during the quiescence of some motion owing to want of stimulus generally induces torpor in the first link of the train of associated motions catenated with it; as the capillaries of the lungs become torpid immediately on immersion of the skin into cold water; yet in some situations an orgasm or excess of action is produced in the first link of the associated motions thus catenated with irritative ones; as in the increased action of the stomach, when the skin is for a time exposed to cold air; which may in part be ascribed to the general increase of action of the whole system, owing to the diminished expenditure of sensorial power, but particularly of the parts, which have habitually acted together; as when one arm is paralytic the other is liable to more frequent or almost continual motion; and when one eye becomes blind the other frequently becomes stronger; which is well known to farriers, who are said sometimes to destroy the sight of one eye to strengthen that of the other in diseased horses. Hence there is sometimes a direct sympathy, and sometimes a reverse one succeeds the torpor occasioned by defect of stimulus, the latter of which is perhaps owing to a certain time being required for the production of an accumulation of the sensorial power of irritation by the nervous branches of the torpid organ; which accumulation is now in part or entirely derived to the next link of the association. Thus in going into a coldish bath, as into a river in the summer months, we at first experience a difficulty of breathing from the torpid action of the pulmonary capillaries, owing to the deficient excitement of the sensorial power of association in consequence of the torpor of the cutaneous capillaries. But in a very short time, as in one minute, the sensorial power of irritation becomes accumulated by the inactivity of the cutaneous capillaries; and as its superabundance becomes now expended on the pulmonary capillaries, the difficult respiration ceases; though the cutaneous capillaries continue torpid by their contact with the cold water, and consequently the sensorial power of association, which used to contribute to actuate the pulmonary capillaries, is less excited. 8. In like manner when there exists an accumulation of the sensorial power of association, owing to defect of its excitement by some previous irritative or associate motions, it is generally accompanied for a certain time by a torpor not only of the link first affected, but of the subsequent parts, or of the whole train of associated motions, as in the cold fits of intermittent fevers. Yet after a time an increased action of the next links of associated motions succeeds the torpor of the first, as the absorbent vessels of the lungs act more violently in consequence of the deficient action of those of the stomach; and the skin at the commencement of sickness is pale and cold, but in a little time becomes flushed and warm. Thus we see in associate motions, which are rendered torpid by defect of excitement, that sometimes a direct, and sometimes a reverse sympathy succeeds in the subsequent links of the chain. But I believe where a torpor of irritative or of the associate motions is caused by a previous too great expenditure or exhaustion of the sensorial powers of irritation or association, no increase of action in the subsequent link ever occurs, or not till after a very long time. Thus when the stomach becomes torpid by previous violent exertion, and consequent exhaustion of the sensorial power of irritation, as after intoxication with wine or opium, or after the exhibition of some violent emetic drug, the torpor is communicated to the heart and arteries, as in continued fevers with weak pulse. But where the torpor of the stomach is produced from defective association, as in sea-sickness; or in the sickness which occurs, when a stone stimulates the ureter; no torpor is then communicated to the heart and arteries. For in the former case there is no accumulation of sensorial power in the stomach, which was previously exhausted by too great stimulus; but in the latter case the accumulation of sensorial power in the stomach during its torpor is evinced by this circumstance; that in sea-sickness the patients eat and drink voraciously at intervals; and the pulse is generally not affected by the sickness occasioned by a stone in the ureter. For the action of the stomach is then lessened, and in consequence becomes retrograde, not owing to the exhaustion of the sensorial power of irritation, but to the want of excitement of the sensorial power of association; which is caused by the defective action of the ureter, which becomes occasionally torpid by the great stimulus of the stone it contains; or which is caused by the great exhaustion of sensorial power by the pain; which affects the ureter without exciting inflammation, or increased action of it. 9. Thus though the stomach after the great stimulus of intoxication from excess of wine or opium will continue many hours without accumulation of sensorial power, as appears from the patient's experiencing no appetite at the intervals of sickness; yet after long abstinence from food, at length not only the exhausted quantity of sensorial power is renewed, but an accumulation of it at length occurs, and hunger returns. In this situation the stomach is generally about a whole day before it regains its usual powers of digestion; but if it has been still more violently stimulated, and its actions further impaired, a still more permanent torpor along with a continued fever with weak pulse is liable to occur; and a fourth part, or a half, or three fourths, or a whole lunar period passes, before it recovers its due irritability and consequent action. In similar manner, after a person has been confined in a very warm room for some hours, the cutaneous capillaries, with their secretory and absorbent vessels, become exhausted of their sensorial power of irritation by the too great violent exertions occasioned by the unusual stimulus of heat; and in coming into a colder atmosphere an inactivity of the cutaneous vessels exists at first for some time without accumulation of sensorial power; as is shewn by the continuance of the pain of cold and the paleness; but after a time both the pain of cold and paleness vanish, which now indicates an accumulation of the sensorial power of irritation, as less degrees of heat stimulate the system into due action. In the same manner, after any one has been some time in the summer sunshine, on coming into a dark cell he continues much longer before he can clearly distinguish objects, than if his eyes had only been previously exposed to the light of a cloudy day in winter; because the sensorial power of irritation, and consequent sensation, had in the first case been previously much expended or exhausted; and therefore required a much longer time before it could be produced in the brain, or derived to the optic nerves, in such quantity as to restore the deficiency, and to cause an accumulation of it; whereas in the latter case no deficiency had occurred. 10. Thus the accumulation or deficiency of sensorial power in a torpid organ, which had previously been accustomed to perpetual action, depends on the manner in which it becomes torpid; that is, whether by great previous stimulus, or great previous excitement of the power of association; or by defect of its accustomed stimulus, or of its accustomed excitement of the power of association. In the former case the sensorial power is in an exhausted state, and therefore is not likely to become so soon accumulated, as after drunkenness, or exposure to great heat, or to great light; in the latter a great accumulation of sensorial power occurs, as after exposure to cold, or hunger, or darkness. Hence when the stomach continues torpid by previous violent stimulus, as in the exhibition of digitalis, no accumulation of sensorial power of irritation supervenes; and in consequence the motions of the heart and arteries, which are associated with those of the stomach, become weak, and slow, and intermittent, from the defect of the excitement of the sensorial power of association. But what follows? as the actions of the heart and arteries are lessened by the deficient action of the sensorial power of association, and not by previous increased excitement of it; a great accumulation of the sensorial power of association occurs, which is exerted on the pulmonary and cutaneous absorbents by reverse sympathy, and produces a great absorption of the fluid effused into the cellular membrane in anasarca, with dry skin; constituting one kind of atrophy. But if at the same time the secerning vessels of the stomach are stimulated into so violent activity as to induce great consequent torpor, as probably happens when contagious matter is swallowed into the stomach with our saliva, those of the heart and arteries act feebly from the deficient excitement of the power of association; and then the cutaneous and pulmonary secerning vessels act with greater force than natural, owing to the accumulation of the sensorial power of association; and unnatural heat of the skin, and of the breath succeed; but without frequency of pulse, constituting the paresis irritativa of Class I. 2. 1. 2. And lastly, if a paucity of blood attends this paresis, or some other cause inducing a frequency of pulse, the febris inirritativa, or fever with weak pulse, is produced. But on the contrary when the stomach has previously been rendered torpid by defect of stimulus, as by hunger, if food be too hastily supplied, not only great exertion of the stomach itself succeeds, but fever with strong pulse is induced in consequence; that is, the heart and arteries are excited into more energetic action by the excess of the power of association, which catenates their motions with those of the stomach. For the redundancy of sensorial power of irritation, which was accumulated during the inactivity of the stomach, and is now called into action by stimulus, actuates that organ with increased energy, and excites by these increased motions the sensorial power of association; which has also been accumulated during the inactivity of the heart and arteries; and thus these organs also are now excited into greater action. So after the skin has been exposed some hours to greater heat than natural in the warm room, other parts, as the membranes of the nostrils, or of the lungs, or of the stomach, are liable to become torpid from direct sympathy with it, when we come into air of a moderate temperature; whence catarrhs, coughs, and fevers. But if this torpor be occasioned by defect of stimulus, as after being exposed to frosty air, the accumulation of sensorial power is exerted, and a glow of the skin follows, with increased digestion, full respiration, and more vigorous circulation. 11. It may be asked, Why is there a great and constant accumulation of the sensorial power of association, owing to the torpor of the stomach and heart and arteries, in continued fever with weak pulse; which is exerted on the cutaneous and pulmonary capillaries, so as to excite them into increased action for many weeks, and yet no such exuberance of sensorial power produces fever in winter-sleeping animals, or in chlorosis, or apepsia, or hysteria? In winter-sleeping animals I suppose the whole nervous system is torpid, or paralysed, as in the sleep of frozen people; and that the stomach is torpid in consequence of the inactivity or quiescence of the brain; and that all other parts of the body, and the cutaneous capillaries with the rest, labour under a similar torpor. In chlorosis, I imagine, the actions of the heart and arteries, as well as those of the cutaneous and pulmonary capillaries, suffer along with those of the stomach from the deficient stimulus of the pale blood; and that though the liver is probably the seat of the original torpor in this disease, with which all other parts sympathize from defect of the excitation of the sensorial power of association; yet as this torpor occurs in so small a degree as not to excite a shuddering or cold fit, no observable consequences are in general occasioned by the consequent accumulation of sensorial power. Sometimes indeed in chlorosis there does occur a frequent pulse and hot skin; in which circumstances I suppose the heart and arteries are become in some degree torpid by direct sympathy with the torpid liver; and that hence not only the pulse becomes frequent, but the capillaries of the skin act more violently by reverse sympathy with the heart and arteries, owing to the accumulation of the sensorial power of association in them during their torpid state, as occurs in irritative fever. See Article 11 of this Supplement. In apepsia chronica the actions of the stomach are not so far impaired or destroyed as totally to prevent the excitation of the sensorial power of association, which therefore contributes something towards the actions of the heart and arteries, though less than natural, as a weak pulse always I believe attends this disease. There is a torpor of the stomach, and of the upper part of the alimentary canal in hysteria, as is evident from the retrograde actions of the duodenum, stomach, and oesophagus, which constitute the globus hystericus, or sensation of a globe rising into the throat. But as these retrograde actions are less than those, which induce sickness or vomiting, and are not occasioned by previous exhaustion of the sensorial power of irritation, they do not so totally prevent the excitement of the sensorial power of association, as to lessen the motion of the heart and arteries so much as to induce fever; yet in this case, as in apepsia, and in chlorosis, the pulsations of the heart and arteries are weaker than natural, and are sometimes attended with occasionally increased action of the capillaries; as appears from the flushings of the face, and hot skin, which generally form an evening febricula in diseases attended with weak digestion. 12. The increased action, or orgasm, of the cutaneous, pulmonary, and cellular capillaries, with their secerning and absorbent vessels, in those fevers which are attended with deficiency of vital action, exhausts the patient both by the additional expenditure of sensorial power on those organs of secretion, and by the too great absorption of the mucus and fat of the body; whence great debility and great emaciation. Hence one great indication of cure of continued fever with arterial debility is to diminish the too great action of the capillaries; which is to be done by frequent ablutions, or bathing the whole skin in tepid or in cold water, as recommended by Dr. Currie of Liverpool (Philos. Trans. for 1792), for half an hour, twice a day, or at those times when the skin feels dryest and hottest. Much cool air should also be admitted, when the breath of the patient feels hot to one's hand; or when the tongue, especially its middle part, is dry, and covered with a crust of indurated mucus; as these indicate the increased action of the pulmonary capillaries; in the same manner as the dry and hot skin indicates the orgasm of the cutaneous capillaries; and the emaciation of the body that of the cellular ones. For this purpose of abating the action of the capillaries by frequent ablution or fomentation, water of any degree of heat beneath that of the body will be of service, and ought in accurate language to be called a cold bath; but the degree of coldness, where the patient is sensible, should in some measure be governed by his sensations; as it is probable, that the degree of coldness, which is most grateful to him, will also be of the greatest benefit to him. See Class III. 2. 1. 12. and Article 15 of this Supplement. Another great use of frequent ablutions, or fomentations, or baths, in fevers, where the stomach is in some degree torpid, is to supply the system with aqueous fluid by means of the cutaneous absorbents; which is dissipated faster by the increased action of the secerning capillaries, than the stomach can furnish, and occasions great thirst at the intervals of the sickness. IX. _Torpor of the Lungs._ 1. The lungs in many cases of contagion may first be affected with torpor, and the skin become cold by sympathy; in the same manner as a cold skin on going into the cold bath induces difficulty of breathing. Or the stomach may become affected with torpor by its sympathy with the lungs, as in the experiments of Mr. Watt with hydro-carbonate gas; a few respirations of which induced sickness, and even syncope. When the stomach or skin is thus affected secondarily by association, an accumulation of sensorial power occurs much sooner, than when these parts become torpid in consequence of previous excess of stimulus; and hence they sooner recover their accustomed action, and the fever ceases. The particles of contagious matter thus received by respiration somewhat resemble in their effects the acid gases from burning sulphur, or from charcoal; which, if they do not instantly destroy, induce a fever, and the patient slowly recovers. 2. I was some years ago stooping down to look, which way the water oozed from a morass, as a labourer opened it with a spade, to detect the source of the spring, and inhaled a vapour, which occasioned an instant sense of suffocation. Immediately recoiling I believe I inhaled it but once; yet a few hours afterwards in the cool of the evening, when I returned home rather fatigued and hungry, a shivering and cold fit occurred, which was followed by a hot one; and the whole disease began and terminated in about twelve hours without return. In this case the power of fear, or of imagination, was not concerned; as I neither thought of the bad air of a morass before I perceived it; nor expected a fever-fit, till it occurred. In this case the torpor commenced in the lungs, and after a few hours, by the addition of fatigue, and cold, and hunger, was propagated by direct sympathy to the rest of the system. An orgasm or increased action of the whole system was then induced by the accumulation of sensorial power of irritation in the lungs, and of association in the other organs; and when these subsided, the disease ceased. It may be asked, could a torpor of the capillaries of the air-vessels of the lungs be so suddenly produced by great stimulation?--It appears probable, that it might, because great exertion of irritative motions may be instantly produced without our perceiving them; that is, without their being attended by sensation, both in the lungs and stomach; and the organs may become torpid by the great expenditure of the sensorial power of irritation in an instant of time; as paralysis frequently instantly follows too great an exertion of voluntary power. 3. When the capillaries of the lungs act too violently, as in some continued fevers; which is known by the heat of the breath, and by the dryness of the tongue, especially of the middle part of it; not only cooler air might be admitted more freely into a sick room to counteract this orgasm of the pulmonary capillaries; but perhaps the patient might breathe with advantage a mixture of carbonic acid gas, or of hydrogene gas, or of azote with atmospheric air. And on the contrary, when there exists an evident torpor of the pulmonary capillaries, which may be known by the correspondent chilness of the skin; and by a tickling cough, which sometimes attends cold paroxysms of fever, and is then owing to the deficient absorption of the pulmonary mucus, the saline parts of which stimulate the bronchiæ, or air-vessels; a mixture of one part of oxygen gas with 10 or 20 parts of atmospheric air might probably be breathed with great advantage. X. _Torpor of the Brain._ As the inactivity or torpor of the absorbent vessels of the brain is the cause of hydrocephalus internus; and as the deficiency of venous absorption in the brain, or torpor of the extremities of its veins, is believed frequently to be the cause of apoplexies; so there is reason to conclude, that the torpor of the secerning vessels of the brain, which are supposed to produce the sensorial power, may constitute the immediate cause of some fevers with arterial debility. And also that the increased action of these secerning vessels may sometimes constitute the immediate cause of fevers with arterial strength. It is nevertheless probable, that the torpor or orgasm of the sanguiferous, absorbent, or secerning vessels of the brain may frequently exist as a secondary effect, owing to their association with other organs, as the stomach or lungs; and may thus be produced like the torpor of the heart and arteries in inirritative fevers, or like the orgasm of those organs in irritative fevers, or inflammatory ones. Where there exists a torpor of the brain, might not very slight electric shocks passed frequently through it in all directions be used with advantage? Might not fomentations of 94 or 96 degrees of heat on the head for an hour at a time, and frequently repeated, stimulate the brain into action; as in the revival of winter-sleeping animals by warmth? Ether externally might be frequently applied, and a blister on the shaved head. Where the secerning vessels of the brain act with too great energy, as in some inflammatory fevers, might it not be diminished by laying the patient horizontally on a mill-stone, and whirling him, till sleep should be produced, as the brain becomes compressed by the centrifugal force? See Article 15 of this Supplement. XI. _Torpor of the Heart and Arteries._ 1. It was shewn in Class IV. 1. 1. 6. in IV. 2. 1. 2. and in Suppl. I. 6. 3. that a reverse sympathy generally exists between the lacteal and lymphatic branches of the absorbent system. Hence, when the motions of the absorbents of the stomach are rendered torpid or retrograde in fevers with arterial debility, those of the skin, lungs, and cellular membrane, act with increased energy. But the actions of the muscular fibres of the heart and arteries are at the same time associated with those of the muscular fibres of the stomach by direct sympathy. Both these actions occur during the operation of powerful emetics, as squill, or digitalis; while the motions of the stomach continue torpid or retrograde, the cellular and cutaneous absorbents act with greater energy, and the pulsations of the heart and arteries become weaker, and sometimes slower. 2. The increased action of the stomach after a meal, and of the heart and arteries at the same time from the stimulus of the new supply of chyle, seems originally to have produced, and to have established, this direct sympathy between them. As the increased action of the absorbents of the stomach after a meal has been usually attended with diminished action of the other branches of the absorbent system, as mentioned in Class IV. 1. 1. 6. and has thus established a reverse sympathy between them. 2. Besides the reverse sympathy of the absorbent vessels and the muscles of the stomach, and of the heart and arteries, with those of the skin, lungs, and cellular membrane; there exists a similar reverse sympathy between the secerning vessels or glands of the former of these organs with those of the latter; that is the mucous glands of the heart and arteries act generally by direct sympathy with those of the stomach; and the mucous glands of the cellular membrane of the lungs, and of the skin, act by reverse sympathy with them both. Hence when the stomach is torpid, as in sickness, this torpor sometimes only affects the absorbent vessels of it; and then the absorbents of the cellular membrane and the skin only act with increased energy by reverse sympathy. If the torpor affects the muscular fibres of the stomach, those of the heart and arteries act by direct sympathy with it, and a weak pulse is produced, as in the exhibition of digitalis, but without increase of heat. But if the torpor also affects the glands of the stomach, the cutaneous and pulmonary glands act with greater energy by their reverse sympathy with those of the stomach, and of the heart and arteries; and great heat is produced along with increased perspiration both from the skin and lungs. 3. There is some difficulty in explaining, why the actions of the extensive system of capillary glands, which exist on every other membrane and cell in the body for the purpose of secreting mucus and perspirable matter, should so generally act by reverse sympathy with those of the stomach and upper part of the intestines. It was shewn in Class IV. 1. 1. 6. that when the stomach was filled with solid and fluid aliment, the absorbents of the cellular membrane, and of the bladder, and of the skin acted with less energy; as the fluids they were used to absorb and transmit into the circulation, were now less wanted; and that hence by habit a reverse sympathy obtained between these branches of the absorbents of the alimentary canal, and those of the other parts of the body. Now, as at this time less fluid was absorbed by the cutaneous and cellular lymphatics, it would happen, that less would be secreted by their correspondent secerning vessels, or capillary glands; and that hence by habit, these secerning vessels would acquire a reverse sympathy of action with the secerning vessels of the alimentary canal. Thus when the absorption of the tears by the puncta lacrymalia is much increased by the stimulus of snuff; or of an affecting idea, on the nasal dusts, as explained in Sect. XVI. 8. 2. a great increase of the secretion of tears from the lacrymal glands is produced by the direct sympathy of the action of these glands with those of their correspondent absorbents; and that though in this case they are placed at so great a distance from each other. 4. A difficult question here occurs; why does it happen, that in fevers with weak pulse the contractions of the heart and arteries become at the same time more frequent; which also sometimes occurs in chlorosis, and in some hysteric and hypochondriac diseases, and in some insanities; yet at other times the weak pulse becomes at the same time slow, as in the exhibition of digitalis, and in paresis irritativa, described in Class I. 2. 1. 2. which may be termed a fever with slow pulse? this frequency of pulse can not depend on heat, because it sometimes exists without heat, as towards the end of some fevers with debility. Now as apoplexies, which are sometimes ascribed to fulness of blood, are attended with slow pulse; and as in animals dying in the slaughter house from deficiency of blood the pulse becomes frequent in extreme; may not the frequency of pulse in fevers with arterial debility be in general owing to paucity of blood? as explained in Sect. XXXII. 2. 3. and its slowness in paresis irritativa be caused by the debility being accompanied with due quantity of blood? or may not the former circumstance sometimes depend on a concomitant affection of the brain approaching to sleep? or to the unusual facility of the passage of the blood through the pulmonary and aortal capillaries? in which circumstance the heart may completely empty itself at each pulsation, though its contractions may be weak. While the latter depends on the difficulty of the passage of the blood through the pulmonary or aortal capillaries, as in the cold fits of intermittents, and in some palpitations of the heart, and in some kinds of hæmoptoe? in these cases the increased resistance prevents the heart from emptying itself, and in consequence a new diastole sooner occurs, and thus the number of pulsations becomes greater in a given time. 5. In respect to the sympathies of action, which produce or constitute fever with debility, the system may be divided into certain provinces, which are assentient or opposite to each other. First, the lacteals or absorbent vessels of the stomach, and upper part of the intestines; secondly, the lymphatics or all the other branches of the absorbent vessels, which arise from the skin, mucous membranes, cellular membranes, and the various glands. These two divisions act by reverse sympathy with each other in the hot fits of fever with debility, though by direct sympathy in the cold ones. The third division consists of the secerning vessels of the stomach and upper intestines; and the fourth of the secerning vessels of all the other parts of the body, as the capillary glands of the skin, lungs, and cellular membrane, and the various other glands belonging to the sanguiferous system. Many of these frequently, but the capillaries always, act by reverse sympathy with those of the third division above mentioned in the hot fits of fever with debility, though by direct sympathy with them in the cold fits. Fifthly, the muscular fibres of the stomach, and upper intestines; and sixthly, the muscular fibres of the heart and arteries. The actions of these two last divisions of moving fibres act by direct sympathy with each other, both in the cold and hot fits of fevers with debility. The efficient cause of those apparent sympathies in fevers with weak pulse may be thus understood. In the cold paroxysm of fever with weak pulse the part first affected I believe to be the stomach, and that it has become torpid by previous violent exertion, as by swallowing contagious matter mixed with saliva, and not by defect of stimulus, as from cold or hunger. The actions of this important organ, which sympathizes with almost every part of the body, being thus much diminished or nearly destroyed, the sensorial power of association is not excited; which in health contributes to move the heart and arteries, and all the rest of the system; whence an universal torpor occurs. When the hot fit approaches, the stomach in fevers with strong pulse regains its activity by the accumulation of the sensorial power of either irritation, if it was the part first affected, or of association if it was affected in sympathy with some other torpid part, as the spleen or liver; which accumulation is produced during its torpor. At the same time all the other parts of the system acquire greater energy of action by the accumulation of the sensorial power of association, which was produced, during their inactivity in the cold fit. But in fevers with weak pulse the stomach, whose sensorial power of irritation had been previously exhausted by violent action, acquires no such quick accumulation of sensorial power, but remains in a state of torpor after the hot fit commences. The heart and arteries remain also in a state of torpor, because there continues to be no excitement of their power of association owing to the torpid motions of the stomach; but hence it happens, that there exists at this time a great accumulation of the power of association in the less active fibres of the heart and arteries; which, as it is not excited and expended by them, increases the associability of the next link of the associated chain of motions, which consists of the capillaries or other glands; and that in so great a degree as to actuate them with unnatural energy, and thus to produce a perpetual hot fit of fever. Because the associability of the capillaries is so much increased by the accumulation of this power, owing to the lessened activity of the heart and arteries, as to over-balance the lessened excitement of it by the weaker movements of the heart and arteries. 6. When the accumulation of the sensorial power of irritation caused by defect of stimulus is greater in the first link of a train of actions, to which associated motions are catenated, than the deficiency of the excitement of the sensorial power of association in the next link, what happens?--the superabundance of the unemployed sensorial power of the first link is derived to the second; the associability of which thus becomes so greatly increased, that it acts more violently than natural, though the excitement of its power of association by the lessened action of the first link is less than natural. So that in this situation the withdrawing of an accustomed stimulus in some parts of the system will decrease the irritative motions of that part, and at the same time occasion an increase of the associate motion of another part, which is catenated with it. This circumstance nevertheless can only occur in those parts of the system, whose natural actions are perpetual, and the accumulation of sensorial power on that account very great, when their activity is much lessened by the deduction of their usual stimulus; and are therefore only to be found in the sanguiferous system, or in the alimentary canal, or in the glands and capillaries. Of the first of which the following is an instance. The respiration of a reduced atmosphere, that is of air mixed with hydrogene or azote, quickens the pulse, as observed in the case of Mrs. Eaton by Dr. Reynolds and Dr. Thornton; to which Dr. Beddoes adds in a note, that "he never saw an instance in which a lowered atmosphere did not at the moment quicken the pulse, while it weakened the action of the heart and arteries." Considerations on Factitious Airs, by Thomas Beddoes and James Watt, Part III. p. 67. Johnson, London. By the assistance of this new fact the curious circumstance of the quick production of warmth of the skin on covering the head under the bed-clothes, which every one must at some time have experienced, receives a more satisfactory explanation, than that which is given in Class IV. 1. 1. 2. which was printed before this part of Dr. Beddoes's Considerations was published. For if the blood be deprived of its accustomed quantity of oxygen, as in covering the head in bed, and thus breathing an air rendered impure by repeated respiration, or by breathing a factitious air with less proportion of oxygen, which in common respiration passes through the moist membranes of the lungs, and mixes with the blood, the pulsations of the heart and arteries become weaker, and consequently quicker, by the defect of the stimulus of oxygen. And as these vessels are subject to perpetual motion, the accumulation of the sensorial power of irritation becomes so great by their lessened activity, that it excites the vessels next connected, the cutaneous capillaries for instance, into more energetic actions, so as to produce increased heat of the skin, and greater perspiration. How exactly this resembles a continued fever with weak and quick pulse!--in the latter the action of the heart and arteries are lessened by defect of the excitement of the sensorial power of association, owing to the torpor or lessened actions of the stomach; hence the accumulation of the sensorial power of association in this case, as the accumulation of that of irritation in the former, becomes so abundant as to excite into increased action the parts most nearly connected, as the cutaneous capillaries. In respect to the circumstance mentioned by Sydenham, that covering the head in bed in a short time relieved the pertinacious sickness of the patient, it must be observed, that when the action of the heart and arteries become weakened by the want of the due stimulus of the proper quantity of oxygen in the blood, that an accumulation of the sensorial power of irritation occurs in the fibres of the heart and arteries, which then is expended on those of the capillary glands, increasing their actions and consequent secretions and heat. And then the stomach is thrown into stronger action, both by the greater excitement of its natural quantity of the sensorial power of association by the increased actions of the capillaries, and also by some increase of associability, as it had been previously a long time in a state of torpor, or less activity than natural, as evinced by its perpetual sickness. In a manner somewhat similar to this, is the redness of the skin produced in angry people by the superabundance of the unemployed sensorial power of volition, as explained in Class IV. 2. 3. 5. Rubor ex irâ. From hence we learn how, when people in fevers with weak pulse, or in dropsies, become insane, the abundance of the unemployed sensorial power of volition increases the actions of the whole moving system, and cures those diseases. 7. As the orgasm of the capillaries in fevers with weak pulse is immediately caused by the torpid actions of the heart and arteries, as above explained, this supplies us with another indication of cure in such fevers, and that is to stimulate these organs. This may probably be done by some kind of medicines, which are known to pass into the blood unchanged in some of their properties. It is possible that nitre, or its acid, may pass into the blood and increase the colour of it, and thus increase its stimulus, and the same may be supposed of other salts, neutral or metallic? As rubia tinctoria, madder, colours the bones of young animals, it must pass into the blood with its colouring matter at least unchanged, and perhaps many other medicines may likewise affect the blood, and thus act by stimulating the heart and arteries, as well as by stimulating the stomach; which circumstance deserves further attention. Another way of immediately stimulating the heart and arteries would be by transfusing new blood into them. Is it possible that any other fluid besides blood, as chyle, or milk, or water, could, if managed with great art, be introduced safely or advantageously into the vein of a living animal? A third method of exciting the heart and arteries immediately is by increasing the natural stimulus of the blood, and is well worthy experiment in all fevers with weak pulse; and that consists in supplying the blood with a greater proportion of oxygen; which may be done by respiration, if the patient was to breathe either oxygen gas pure, or diluted with atmospheric air, which might be given to many gallons frequently in a day, and by passing through the moist membranes of the lungs, according to the experiments of Dr. Priestley, and uniting with the blood, might render it more stimulant, and thus excite the heart and arteries into greater action! May not some easier method of exhibiting oxygen gas by respiration be discovered, as by using very small quantities of hyper-oxygenated marine acid gas very much diluted with atmospheric air? XII. _Torpor of the Stomach and upper Intestines._ 1. The principal circumstance, which supports the increased action of the capillaries in continued fever with weak pulse, is their reverse sympathy with those of the stomach and upper intestines, or with those of the heart and arteries. The torpor of the stomach and upper intestines is apparent in continued fevers from the total want of appetite for solid food, besides the sickness with which fevers generally commence, and the frequent diarrhoea with indigested stools, at the same time the thirst of the patient is sometimes urgent at the intervals of the sickness. Why the stomach can at this time take fluids by intervals, and not solids, is difficult to explain; except it be supposed, as some have affirmed, that the lacteal absorbents are a different branch from the lymphatic absorbents, and that in this case the former only are in a state of permanent torpor. 2. The torpor of the heart and arteries is known by the weakness of the pulse. When the actions of the absorbents of the stomach are diminished by the exhibition of small doses of digitalis, or become retrograde by larger ones, the heart and arteries act more feebly by direct sympathy; but the cellular, cutaneous, and pulmonary absorbents are excited into greater action. Whence in anasarca the fluids in the cellular membrane throughout the whole body are absorbed during the sickness, and frequently a great quantity of atmospheric moisture at the same time; as appears by the very great discharge of urine, which sometimes happens in these cases; and in ileus the prodigious evacuations by vomiting, which are often a hundred fold greater than the quantity swallowed, evince the great action of all the other absorbents during the sickness of the stomach. 3. But when the stomach is rendered permanently sick by an emetic drug, as by digitalis, it is not probable, that much accumulation of sensorial power is soon produced in this organ; because its usual quantity of sensorial power is previously exhausted by the great stimulus of the foxglove; and hence it seems probable, that the great accumulation of sensorial power, which now causes the increased action of the absorbents, is produced in consequence of the inactivity of the heart and arteries; which inactivity is induced by deficient excitement of the sensorial power of association between those organs and the stomach, and not by any previous exhaustion of their natural quantity of sensorial power; whereas in ileus, where the torpor of the stomach, and consequent sickness, is induced by reverse sympathy with an inflamed intestine, that is, by dissevered or defective association; the accumulation of sensorial power, which in that disease so violently actuates the cellular, pulmonary, and cutaneous absorbents, is apparently produced by the torpor of the stomach and lacteals, and the consequent accumulation of the sensorial power of association in them owing to their lessened action in sickness. 4. This accounts for the dry skin in fevers with weak pulse, where the stomach and the heart and arteries are in a torpid state, and for the sudden emaciation of the body; because the actions of the cellular and cutaneous absorbents are increased by reverse sympathy with those of the stomach, or with those of the heart and arteries; that is by the expenditure of that sensorial power of association, which is accumulated in consequence of the torpor of the stomach and heart and arteries, or of either of them; this also explains the sudden absorption of the milk in puerperal fevers; and contributes along with the heat of the respired air to the dryness of the mucous membrane of the tongue and nostrils. 5. Besides the reverse sympathy, with which the absorbent vessels of the stomach and upper intestines act in respect to all the other absorbent vessels, as in the exhibition of digitalis, and in ileus; there is another reverse sympathy exists between the capillaries, or secretory vessels of the stomach, and those of the skin. Which may nevertheless be occasioned by the accumulation of sensorial power by the torpor of the heart and arteries, which is induced by direct sympathy with the stomach; thus when the torpor of the stomach remains in a fever-fit which might otherwise have intermitted, the torpor of the heart and arteries remains also by direct sympathy, and the increased cutaneous capillary action, and consequent heat, are produced by reverse sympathy; and the fever is thus rendered continual, owing primarily to the torpor of the stomach. 6. The reverse sympathy, which exists between the capillaries of the stomach and the cutaneous capillaries, appears by the chillness of some people after dinner; and contrary-wise by the digestion being strengthened, when the skin is exposed to cold air for a short time; as mentioned in Class IV. 1. 1. 4. and IV. 2. 1. 1. and from the heat and glow on the skin, which attends the action of vomiting; for though when sickness first commences, the skin is pale and cold; as it then partakes of the general torpor, which induces the sickness; yet after the vomiting has continued some minutes, so that an accumulation of sensorial power exists in the capillaries of the stomach, and of the skin, owing to their diminished action; a glow of the skin succeeds, with sweat, as well as with increased absorption. 7. Nevertheless in some circumstances the stomach and the heart and arteries seem to act by direct sympathy with the cutaneous capillaries, as in the flushing of the face and glow of the skin of some people after dinner; and as in fevers with strong pulse. In these cases there appears to be an increased production of sensorial power, either of sensation, as in the blush of shame; or of volition, as in the blush of anger; or of irritation, as in the flushed face after dinner above mentioned. This increased action of the capillaries of the skin along with the increased actions of the stomach and heart is perhaps to be esteemed a synchronous increase of action, rather than a sympathy between those organs. Thus the flushing of the face after dinner may be owing to the secretion of sensorial power in the brain being increased by the association of that organ with the stomach, in a greater proportion than the increased expenditure of it, or may be owing also to the stimulus of new chyle received into the blood. 8. When the stomach and the heart and arteries are rendered torpid in fevers, not only the cutaneous, cellular, and pulmonary absorbents are excited to act with greater energy; but also their correspondent capillaries and secerning vessels or glands, especially perhaps those of the skin, are induced into more energetic action. Whence greater heat, a greater secretion of perspirable matter, and of mucus; and a greater absorption of them both, and of aerial moisture. These reverse sympathies coincide with other animal facts, as in eruption of small pox on the face and neck the feet become cold, while the face and neck are much flushed; and in the hemiplagia, when one arm and leg become disobedient to volition, the patient is perpetually moving the other. Which are well accounted for by the accumulation of sensorial power in one part of an associated series of actions, when less of it is expended by another part of it; and by a deficiency of sensorial power in the second link of association, when too much of it is expended by the first. 9. This doctrine of reverse sympathy enables us to account for that difficult problem, why in continued fevers the increased action of the cutaneous, cellular, and pulmonary capillaries proceeds without interruption or return of cold fit; though perhaps with some exacerbations and remissions; and that during a quarter, or half, or three quarters, or a whole lunation; while at the same time the pulsations of the heart and arteries are weaker than natural. To this should be added the direct sympathy, which exists between the peristaltic motions of the fibres of the stomach, and the pulsations of the heart. And that the stomach has become torpid by the too great stimulus of some poisonous or contagious matter; and this very intricate idea of continued fever with feeble pulse is reduced to curious simplicity. The direct sympathy of the stomach and heart and arteries not only appears from the stronger and slower pulse of persons exhausted by fatigue, after they have drank a glass of wine, and eaten a few mouthfuls; but appears also from the exhibition of large doses of digitalis; when the patient labours under great and incessant efforts to vomit, at the same time that the actions of the absorbent system are known to be much increased by the hasty absorption of the serous fluid in anasarca, the pulsations of the heart become slow and intermittent to an alarming degree. See Class IV. 2. 1. 17. and 18. 10. It would assist us much in the knowledge and cure of fevers, if we could always determine, which part of the system was primarily affected; and whether the torpor of it was from previous excess or defect of stimulus; which the industry of future observers must discover. Thus if the stomach be affected primarily, and that by previous excess of stimulus, as when certain quantities of opium, or wine, or blue vitriol, or arsenic, are swallowed, it is some time in recovering the quantity of sensorial power previously exhausted by excess of stimulus, before any accumulation of it can occur. But if it be affected with torpor secondarily, by sympathy with some distant part; as with the torpid capillaries of the skin, that is by defective excitement of the sensorial power of association; or if it be affected by defect of stimulus of food or of heat; it sooner acquires so much accumulation of sensorial power, as to be enabled to accommodate itself to its lessened stimulus by increase of its irritability. Thus in the hemicrania the torpor generally commences in a diseased tooth, and the membranes about the temple, and also those of the stomach become torpid by direct synchronous sympathy; and pain of the head, and sickness supervene; but no fever or quickness of pulse. In this case the torpor of the stomach is owing to defect of the sensorial power of association, which is caused by the too feeble actions of the membranes surrounding the diseased tooth, and thus the train of sympathy ceases here without affecting the motions of the heart and arteries; but where contagious matter is swallowed into the stomach, the stomach after a time becomes torpid from exhaustion of the sensorial power of irritation, and the heart and arteries act feebly from defect of the excitement of the power of association. In the former case the torpor of the stomach is conquered by accumulation of the power of association in one or two whole days; in the latter it recovers by accumulation of the power of irritation in three or four weeks. In intermittent fevers the stomach is generally I believe affected secondarily by sympathy with the torpid cutaneous capillaries, or with some internal torpid viscus, and on this account an accumulation of sensorial power arises in a few hours sufficient to restore the natural irritability of this organ; and hence the hot fit succeeds, and the fever intermits. Or if this accumulation of sensorial power becomes excessive and permanent, the continued fever with strong pulse is produced, or febris irritativa. In continued fevers the stomach is frequently I suppose affected with torpor by previous excess of stimulus, and consequent exhaustion of sensorial power, as when contagious matter is swallowed with the saliva, and it is then much slower in producing an accumulation of sensorial power sufficient to restore its healthy irritability; which is a frequent cause of continued fever with weak pulse or febris inirritativa. Which consists, after the cold fit is over, in a more frequent and more feeble action of the heart and arteries, owing to their direct sympathy with the muscular fibres of the torpid stomach; together with an increased action of the capillaries, glands, and absorbents of the skin, and cellular membrane, owing to their reverse sympathy with the torpid capillaries, glands, and absorbents of the stomach, or with those of the heart and arteries. Or in more accurate language. 1. The febris inirritativa, or fever with weak pulse, commences with torpor of the stomach, occasioned by previous exhaustion of sensorial power of irritation by the stimulus of contagious matter swallowed with the saliva. 2. The whole system becomes torpid from defect of the excitement or the sensorial power of association owing to the too feeble actions of the stomach, this is the cold fit. 3. The whole system, except the stomach with the upper intestines, and the heart and arteries, falls into increased action, or orgasm, owing to accumulation of sensorial power of association during their previous torpor, this is the hot fit. 4. The stomach and upper intestines have not acquired their natural quantity of sensorial power of irritation, which was previously exhausted by violent action in consequence of the stimulus of contagious matter, and the heart and arteries remain torpid from deficient excitement of the sensorial power of association owing to the too feeble actions of the stomach. 5. The accumulation of sensorial power of association in consequence of the torpor of the heart and arteries occasions a perpetual orgasm, or increased action of the capillaries. 11. From hence it may be deducted first, that when the torpor of the stomach first occurs, either as a primary effect, or as a secondary link of some associate train or circle of motions, a general torpor of the system sometimes accompanies it, which constitutes the cold fit of fever; at other times no such general torpor occurs, as during the operation of a weak emetic, or during sea-sickness. Secondly. After a time it generally happens, that a torpor of the stomach ceases, and its actions are renewed with increase of vigour by accumulation of sensorial power during its quiescence; as after the operation of a weak emetic, or at the intervals of sea-sickness, or after the paroxysm of an intermittent fever. Thirdly. The stomach is sometimes much slower in recovering from a previous torpor, and is then the remote cause of continued fever with weak pulse; which is owing to a torpor of the heart and arteries, produced in consequence of the deficient excitement of the power of association by the too weak actions of the stomach; and to an orgasm of the capillaries of the other parts of the system, in consequence of the accumulation of sensorial power occasioned by the inactivity of the heart and arteries. Fourthly. The torpor of the stomach is sometimes so complete, that probably the origin of its nerves is likewise affected, and then no accumulation of sensorial power occurs. In this case the patient dies for want of nourishment; either in three or four weeks, of the inirritative fever; or without quick pulse, by what we have called paresis irritativa. Or he continues many years in a state of total debility. When this torpor suddenly commences, the patient generally suffers epileptic fits or temporary insanity from the disagreeable sensation of so great a torpor of the stomach; which also happens sometimes at the eruption of the distinct small pox; whence we have termed this disease anorexia epileptica. See Class II. 2. 2. 1. and III. 1. 1. 7. and Suppl. I. 14. 3. Fifthly. When this torpor of the stomach is less in degree or extent, and yet without recovering its natural irritability by accumulation of sensorial power, as it does after the cold fit of intermittent fever, or after the operation of mild emetics, or during syncope; a permanent defect of its activity, and of that of the upper intestines, remains, which constitutes apepsia, cardialgia, hypochondriasis, and hysteria. See Class I. 3. 1. 3. and I. 2. 4. 5. Sixthly. If the torpor of the stomach be induced by direct sympathy, as in consequence of a previous torpor of the liver, or spleen, or skin, an accumulation of sensorial power will sooner be produced in the stomach; because there has been no previous expenditure of it, the present torpor of the stomach arising from defect of association. Hence some fevers perfectly intermit, the stomach recovering its complete action after the torpor and consequent orgasm, which constitute the paroxysm of fever, are terminated. Seventhly. If the torpor of the stomach be owing to defect of irritation, as to the want of food, an accumulation of sensorial power soon occurs with an increase of digestion, if food be timely applied; or with violent inflammation, if food be given in too great quantity after very long abstinence. Eighthly. If the torpor of the stomach be induced by defect of pleasurable sensation, as when sickness is caused by the suggestion of nauseous ideas; an accumulation of sensorial power soon occurs, and the sickness ceases with the return of hunger; for in this case the inactivity of the stomach is occasioned by the subduction of agreeable sensation, which acts as a subduction of stimulus, and not by exhausting the natural quantity of sensorial power in the fibres or nerves of the stomach. Ninthly. If the torpor of the stomach be induced by a twofold cause, as in sea-sickness. See Vertigo rotatoria. Class IV. 2. 1. 10. in which the first link of association acts too strongly, and in consequence expends more than usual of the sensorial power of irritation; and secondly in which sensation is produced between the links of association, and dissevers or enfeebles them; the accumulation of sensorial power soon occurs in the stomach; as no previous expenditure of it in that organ has occurred. Whence in sea-sickness the persons take food with eagerness at times, when the vertigo eases for a few minutes. Tenthly. If the gastric torpor be induced by previous violent exertion, as after intoxication, or after contagious matter has been swallowed, or some poisons, as digitalis, or arsenic; an accumulation of sensorial power very slowly succeeds; whence long sickness, or continued fever, because the quantity of sensorial power already wasted must first be renewed, before an accumulation of it can be produced. 12. This leads us to a second indication of cure in continued fevers, which consists in strengthening the actions of the stomach; as the first indication consisted in decreasing the actions of the cutaneous capillaries and absorbents. The actions of the stomach may sometimes be increased by exhibiting a mild emetic; as an accumulation of sensorial power in the fibres of the stomach is produced during their retrograde actions. Besides the evacuation of any noxious material from the stomach and duodenum, and from the absorbents, which open their mouths on their internal surfaces, by their retrograde motion. It is probable, that when mild emetics are given, as ipecacuanha, or antimonium tartarizatum, or infusion of chamomile, they are rejected by an inverted motion of the stomach and oesophagus in consequence of disagreeable sensation, as dust is excluded from the eye; and these actions having by previous habit been found effectual, and that hence there is no exhaustion of the sensorial power of irritation. But where strong emetics are administered, as digitalis, or contagious matter, the previous exhaustion of the sensorial power of irritation seems to be a cause of the continued retrograde actions and sickness of the stomach. An emetic of the former kind may therefore strengthen the power of the stomach immediately after its operation by the accumulation of sensorial power of irritation during its action. See Class IV. 1. 1. Another method of decreasing the action of the stomach for a time, and thence of increasing it afterwards, is by the accumulation of the sensorial power of irritation during its torpor; is by giving ice, iced water, iced creams, or iced wine. This accounts for the pleasure, which many people in fevers with weak pulse express on drinking cold beverage of any kind. A second method of exciting the stomach into action, and of decreasing that of the capillaries in consequence, is by the stimulus of wine, opium, bark, metallic salts of antimony, steel, copper, arsenic, given in small repeated quantities; which so long as they render the pulse slower are certainly of service, and may be given warm or cold, as most agreeable to the patient. For it is possible, that the capillaries of the stomach may act too violently, and produce heat, at the same time that the large muscles of it may be in a torpid state; which curious circumstance future observations must determine. Thirdly. Hot fomentation on the region of the stomach might be of most essential service by its stimulus, as heat penetrates the system not by the absorbent vessels, but by external influence; whence the use of hot fomentation to the head in torpor of the brain; and the use of hot bath in cases of general debility, which has been much too frequently neglected from a popular error occasioned by the unmeaning application of the word relaxation to animal power. If the fluid of heat could be directed to pass through particular parts of the body with as little diffusion of its influence, as that of electricity in the shocks from the coated jar, it might be employed with still greater advantage. Fourthly. The use of repeated small electric shocks through the region of the stomach might be of service in fevers with weak pulse, and well deserves a trial; twenty or thirty small shocks twice a day for a week or two would be a promising experiment. Fifthly. A blister on the back, or sides, or on the pit of the stomach, repeated in succession, by stimulating the skin frequently strengthens the action of the stomach by exciting the sensorial power of association; this especially in those fevers where the skin of the extremities, as of the hands or nose or ears, sooner becomes cold, when exposed to the air, than usual. Sixthly. The action of the stomach may be increased by preventing too great expenditure of sensorial power in the link of previous motion with which it is catenated, especially if the action of that link be greater than natural. Thus as the capillaries of the skin act too violently in fevers with weak pulse, if these are exposed to cold air or cold water, the sensorial power, which previously occasioned their orgasm, becomes accumulated, and tends to increase the action of the stomach; thus in those fevers with weak pulse and hot skin, if the stomach be stimulated by repeated small doses of bark and wine or opium, and be further excited at the same time by accumulation of sensorial power occasioned by rendering the capillaries torpid by cold air or water, this twofold application is frequently attended with visible good effect. By thus stimulating the torpid stomach into greater action, the motions of the heart and arteries will likewise be increased by the greater excitement of the power of association. And the capillaries of the skin will cease to act so violently, from their not possessing so great a superfluity of sensorial power as during the greater quiescence of the stomach and of the heart and arteries. Which is in some circumstances similar to the curious phenomenon mentioned in Class IV. 2. 2. 10; where, by covering the chill feet with flannel at the eruption of the small-pox, the points of the flannel stimulate the skin of the feet into greater action, and the quantity of heat, which they possess, is also confined, or insulated, and further increases by its stimulus the activity of the cutaneous vessels of the feet; and by that circumstance abates the too great action of the capillaries of the face, and the consequent heat of it. XIII. _Case of continued fever._ The following case of continued fever which I frequently saw during its progress, as it is less complicate than usual, may illustrate this doctrine. Master S. D. an active boy about eight years of age, had been much in the snow for many days, and sat in the classical school with wet feet; he had also about a fortnight attended a writing school, where many children of the lower order were instructed. He was seized on February the 8th, 1795, with great languor, and pain in his forehead, with vomiting and perpetual sickness; his pulse weak, but not very frequent. He took an emetic, and on the next day, had a blister, which checked the sickness only for a few hours; his skin became perpetually hot, and dry; and his tongue white and furred; his pulse when asleep about 104 in a minute, and when awake about 112. Fourth day of the disease. He has had another blister, the pain of his head is gone, but the sickness continues by intervals; he refuses to take any solid food, and will drink nothing but milk, or milk and water, cold. He has two or three very liquid stools every day, which are somtimes green, but generally of a darkish yellow, with great flatulency both upwards and downwards at those times. An antimonial powder was once given, but instantly rejected; a spoonful of decoction of bark was also exhibited with the same event. His legs are bathed, and his hands and face are moistened twice a day for half an hour in warmish water, which is nevertheless much colder than his skin. Eighth day. His skin continues hot and dry without any observable remissions, with liquid stools and much flatulency and sickness; his water when observed was of a straw colour. He has asked for cyder, and drinks nearly a bottle a day mixed with cold water, and takes three drops of laudanum twice a day. Twelfth day. He continues much the same, takes no milk, drinks only cyder and water, skin hot and dry, tongue hot and furred, with liquid stools, and sickness always at the same time; sleeps much. Sixteenth day. Was apparently more torpid, and once rather delirious; pulse 112. Takes only capillaire and water; sleeps much. Twentieth day. Pulse 100, skin dry but less hot, liquid stools not so frequent, he is emaciated to a great degree, he has eaten half a tea-cup full of custard to day, drinks only capillaire and water, has thrice taken two large spoonfuls of decoction of bark with three drops of laudanum, refuses to have his legs bathed, and will now take nothing but three drops of laudanum twice a day. Twenty-fourth day. He has gradually taken more custard every day, and began to attend to some new play things, and takes wine syllabub. Twenty-eighth day. He daily grows stronger, eats eggs, and and butter, and sleeps immediately after his food, can creep on his hands and knees, but cannot stand erect. Thirty-second day. He cannot yet stand alone safely, but seems hourly to improve in strength of body, and activity of mind. In this case the remote cause of his fever could not be well ascertained, as it might be from having his feet cold for many successive days, or from contagion; but the latter seems more probable, because his younger brother became ill of a similar fever about three weeks afterwards, and probably received the infection from him. The disease commenced with great torpor of the stomach, which was shewn by his total aversion to solid food, and perpetual sickness; the watery stools, which were sometimes green, or of a darkish yellow, were owing to the acrimony, or acidity, of the contents of the bowels; which as well as the flatulency were occasioned by indigestion. This torpor of the stomach continued throughout the whole fever, and when it ceased, the fever ceased along with it. The contagious material of this fever I suppose to have been mixed with the saliva, and swallowed into the stomach; that it excited the vessels, which constitute the stomach, into the greatest irritative motion like arsenic; _which might not be perceived, and yet might render that organ paralytic or inirritable in a moment of time_; as animals sometimes die by one single exertion, and consequent paralysis, without a second struggle; as by lightning, or being shot through the back part of the brain; of both which I have seen instances. I had once an opportunity of inspecting two oxen, a few minutes after they were killed by lightning under a crab-tree on moist ground in long grass; and observed, that they could not have struggled, as the grass was not pressed or bent near them; I have also seen two horses shot through the cerebellum, who never once drew in their legs after they first stretched them out, but died instantaneously; in a similar manner the lungs seem to be rendered instantly inanimate by the fumes of burning sulphur. The lungs may be sometimes primarily affected with contagious matter floating in the atmosphere as well as the stomach, as mentioned in article 9. of this Supplement. But probably this may occur much less frequently, because the oxygene of the atmosphere does not appear to be taken into the blood by animal absorption, as the saliva in the stomach, but passes through the moist membranes into the blood, like the ethereal fluids of electricity or heat, or by chemical attraction, and in consequence the contagious matter may be left behind; except it may sometimes be absorbed along with the mucus; of which however in this case there appeared no symptoms. The tonsils are other organs liable to receive contagious matter, as in the small-pox, scarlet-fever, and in other sensitive inirritated fevers; but no symptom of this appeared here, as the tonsils were at no time of the fever inflamed, though they were in this child previously uncommonly large. The pain of the forehead does not seem to have been of the internal parts of the head, because the nerves, which serve the stomach, are not derived from the anterior part of the brain; but it seems to have been owing to a torpor of the external membranes about the forehead from their direct sympathy with those of the stomach; that is, from the deficient excitement of the sensorial power of association; and seemed in some measure to be relieved by the emetics and blisters. The pulsations of the heart were weaker and in consequence quicker than natural, owing to their direct sympathy with the torpid peristaltic motions of the stomach; that is to the deficient excitement of the sensorial power of association. The action of the cutaneous capillaries and absorbents were stronger than natural, as appeared by the perpetual heat and dryness of the skin; which was owing to their reverse sympathy with the heart and arteries. This weaker and quicker action of the heart and arteries, and the stronger action of the cutaneous capillaries and absorbents, continued throughout the disease, and may be said to have constituted the fever, of which the torpor of the stomach was the remote cause. His tongue was not very much furred or very dry, nor his breath very hot; which shewed, that there was no great increase of the action of the mucous absorbents, nor of the pulmonary capillaries, and yet sufficient to produce great emaciation. His urine was nearly natural both in quantity and colour; which shewed, that there was no increase of action either of the kidnies, or of the urinary absorbents. The bathing his legs and hands and face for half an hour twice a day seemed to refresh him, and sometimes made his pulse slower, and thence I suppose stronger. This seems to have been caused by the water, though subtepid, being much below the heat of his skin, and consequently contributing to cool the capillaries, and by satiating the absorbents to relieve the uneasy sensation from the dryness of the skin. He continued the use of three drops of tincture of opium from about the eighth day to the twenty-fourth, and for the three preceding days took along with if two large spoonfuls of an infusion of bark in equal parts of wine and water. The former of these by its stimulus seemed to decrease his languor for a time, and the latter to strengthen his returning power of digestion. The daily exacerbations or remissions were obscure, and not well attended to; but he appeared to be worse on the fourteenth or fifteenth days, as his pulse was then quickest, and his inattention greatest; and he began to get better on the twentieth or twenty-first days of his disease; for the pulse then became less frequent, and his skin cooler, and he took rather more food: these circumstances seemed to observe the quarter periods of lunation. XIV. _Termination of continued fever._ 1. When the stomach is primarily affected with torpor not by defect of stimulus, but in consequence of the previous exhaustion of its sensorial power; and not secondarily by its association with other torpid parts; it seems to be the general cause of the weak pulsations of the heart and arteries, and the consequent increased action of the capillaries, which constitute continued fever with weak pulse. In this situation if the patient recovers, it is owing to the renovation of life in the torpid stomach, as happens to the whole system in winter-sleeping animals. If he perishes, it is owing to the exhaustion of the body for want of nourishment occasioned by indigestion; which is hastened by the increased actions of the capillaries and absorbents. 2. When the stomach is primarily affected by defect of stimulus, as by cold or hunger; or secondarily by defect of the power of association, as in intermittent fevers; or lastly in consequence of the introduction of the sensorial power of sensation, as in inflammatory diseases; the actions of the heart and arteries are not diminished, as when the stomach is primarily affected with torpor by its previous exhaustion of sensorial power, but become greatly increased, producing irritative or inflammatory fever. Where this fever is continued, though with some remissions and exacerbations, the excessive action is at length so much lessened by expenditure of sensorial power, as to gradually terminate in health; or it becomes totally exhausted, and death succeeds the destruction of the irritability and associability of the system. 3. There is also another termination of the diseases in consequence of great torpor of the stomach, which are not always termed fevers; one of these is attended with so great and universal torpor, that the patient dies in the first cold fit; that is, within twelve hours or less of the first seizure; this is commonly termed sudden death. But the quickness of the pulse, and the coldness with shuddering, and with sick stomach, distinguished a case, which I lately saw, from the sudden deaths occasioned by apoplexy, or ruptured blood-vessels. In hemicrania I believe the stomach is always affected secondarily, as no quickness of pulse generally attends it, and as the stomach recovers its activity in about two whole days. But in the following case, which I saw last week, I suppose the stomach suddenly became paralytic, and caused in about a week the death of the patient. Miss ----, a fine young lady about nineteen, had bathed a few times, about a month before, in a cold spring, and was always much indisposed after it; she was seized with sickness, and cold shuddering, with very quick pulse, which was succeeded by a violent hot fit; during the next cold paroxysm she had a convulsion fit; and after that symptoms of insanity, so as to strike and bite the attendants, and to speak furious language; the same circumstances occurred during a third fit, in which I believe a strait waistcoat was put on, and some blood taken from her; during all this time her stomach would receive no nutriment, except once or twice a little wine and water. On the seventh day of the disease, when I saw her, the extremities were cold, the pulse not to be counted and she was unable to swallow, or to speak; a clyster was used with turpentine and musk and opium, with warm fomentations, but she did not recover from that cold fit. In this case the convulsion fit and the insanity seem to have been violent efforts to relieve the disagreeable sensation of the paralytic stomach; and the quick pulse, and returning fits of torpor and of orgasm, evinced the disease to be attended with fever, though it might have been called anorexia maniacalis, or epileptica. 4. Might not many be saved in these fevers with weak pulse for a few weeks by the introduction of blood into a vein, once in two or three days; which might thus give further time for the recovery of the torpid stomach? Which seems to require some weeks to acquire its former habits of action, like the muscles of paralytic patients, who have all their habits of voluntary associations to form afresh, as in infancy. If this experiment be again tried on the human subject, it should be so contrived, that the blood in passing from the well person to the sick one should not be exposed to the air; it should not be cooled or heated; and it should be measured; all which may be done in the following manner. Procure two silver pipes, each about an inch long, in the form of funnels, wide at top, with a tail beneath, the former something wider than a swan-quill, and the latter less than a small crow-quill. Fix one of these silver funnels by its wide end to one end of the gut of a chicken fresh killed about four or six inches long, and the other to the other end of the gut; then introduce the small end of one funnel into the vein of the arm of a well person downwards towards the hand; and laying the gut with the other end on a water-plate heated to 98 degrees in a very warm room; let the blood run through it. Then pressing the finger on the gut near the arm of the well person, slide it along so as to press out one gutful into a cup, in order to ascertain the quantity by weight. Then introduce the other end of the other funnel into a similar vein in the arm of the sick person upwards towards the shoulder; and by sliding one finger, and then another reciprocally, along the chicken's gut, so as to compress it, from the arm of the well person to the arm of the sick one, the blood may be measured, and thus the exact quantity known which is given and received. See Class I. 2. 3. 25. XV. _Inflammation excited in fever._ 1. When the actions of any part of the system of capillaries are excited to a certain degree, sensation is produced, along with a greater quantity of heat, as mentioned in the fifth article of this supplement. When this increased capillary action becomes still more energetic, by the combined sensorial powers of sensation with irritation, new fibres are secreted, or new fluids, (which harden into fibres like the mucus secreted by the silk-worm, or spider, or pinna,) from which new vessels are constructed; it is then termed inflammation: if this exists in the capillary vessels of the cellular membrane or skin only, with feeble pulsations of the heart and arteries, the febris sensitiva inirritata, or malignant fever, occurs; if the coats of the arteries are also inflamed, the febris sensitiva irritata, or inflammatory fever, exists. In all these fevers the part inflamed is called a phlegmon, and by its violent actions excites so much pain, that is, so much of the sensorial power of sensation, as to produce more violent actions, and inflammation, throughout the whole system. Whence great heat from the excited capillaries of the skin, large and quick pulsations of the heart, full and hard arteries, with great universal secretions and absorptions. These perpetually continue, though with exacerbations and remissions; which seem to be governed by solar or lunar influence. 2. In this situation there generally, I suppose, exists an increased activity of the secerning vessels of the brain, and consequently an increased production of sensorial power; in less violent quantity of this disease however the increase of the action of the heart and arteries may be owing simply to the accumulation of sensorial power of association in the stomach, when that organ is affected by sympathy with some inflamed part. In the same manner as the capillaries are violently and permanently actuated by the accumulation of the sensorial power of association in the heart and arteries, when the stomach is affected primarily by contagious matter, and the heart and arteries secondarily. Thus I suspect, that in the distinct small-pox the stomach is affected secondarily by sympathy with the infected tonsils or inoculated arm; but that in the confluent small-pox the stomach is affected primarily, as well as the tonsils, by contagious matter mixed with the saliva, and swallowed. 3. In inflammatory fevers with great arterial action, as the stomach is not always affected with torpor, and as there is a direct sympathy between the stomach and heart, some people have believed, that nauseating doses of some emetic drug, as of antimonium tartarizatum, have been administered with advantage, abating by direct sympathy the actions of the heart. This theory is not ill founded, and the use of digitalis, given in small doses, as from half a dram to a dram of the saturated tincture, two or three times a day, as well as other less violent emetic drugs, would be worth the attention of hospital physicians. Sickness might also be produced probably with advantage by whirling the patient in a chair suspended from the cieling by two parallel cords; which after being revolved fifty or one hundred times in one direction, would return with great circular velocity, and produce vertigo, similar I suppose to sea-sickness. And lastly the sickness produced by respiring an atmosphere mixed with one tenth of carbonated hydrogen, discovered by Mr. Watt, and published by Dr. Beddoes, would be well worthy exact and repeated experiment. 4. Cool air, cool fomentations, or ablutions, are also useful in this inflammatory fever; as by cooling the particles of blood in the cutaneous and pulmonary vessels, they must return to the heart with less stimulus, than when they are heated above the natural degree of ninety-eight. For this purpose snow and ice have been scattered on the patients in Italy; and cold bathing has been used at the eruption of the small pox in China, and both, it is said, with advantage. See Class III. 2. 1. 12. and Suppl. I. 8. 5. The lancet however with repeated mild cathartics is the great agent in destroying this enormous excitement of the system, so long as the strength of the patient will admit of evacuations. Blisters over the painful part, where the phlegmon or topical inflammation is situated, after great evacuation, is of evident service, as in pleurisy. Warm bathing for half an hour twice a day, when the patient becomes enfeebled, is of great benefit, as in peripneumony and rheumatism. 6. When other means fail of success in abating the violent excitement of the system in inflammatory diseases, might not the shaved head be covered with large bladders of cold water, in which ice or salt had been recently dissolved; and changed as often as necessary, till the brain is rendered in some degree torpid by cold?--Might not a greater degree of cold, as iced water, or snow, be applied to the cutaneous capillaries? 7. Another experiment I have frequently wished to try, which cannot be done in private practice, and which I therefore recommend to some hospital physician; and that is, to endeavour to still the violent actions of the heart and arteries, after due evacuations by venesection and cathartics, by gently compressing the brain. This might be done by suspending a bed, so as to whirl the patient round with his head most distant from the center of motion, as if he lay across a millstone, as described in Sect. XVIII. 20. For this purpose a perpendicular shaft armed with iron gudgeons might have one end pass into the floor, and the other into a beam in the cieling, with an horizontal arm, to which a small bed might be readily suspended. By thus whirling the patient with increasing velocity sleep might be produced, and probably the violence of the actions of the heart and arteries might be diminished in inflammatory fevers; and, as it is believed, that no accumulation of sensorial power would succeed a torpor of the origin of the nerves, either thus procured by mechanical compression, or by the bladder-cap of cold water above described, the lives of thousands might probably be saved by thus extinguishing the exacerbations of febrile paroxysms, or preventing the returns of them. In fevers with weak pulse sleep, or a degree of stupor, thus produced, might prevent the too great expenditure of sensorial power, and thus contribute to preserve the patient. See Class I. 2. 5. 10. on stupor. What might be the consequence of whirling a person with his head next the center of motion, so as to force the blood from the brain into the other parts of the body, might be discovered by cautious experiment without danger, and might probably add to our ability of curing fever. XVI. _Recapitulation._ 1. The sensorial power causes the contraction of the fibres, and is excited into action by four different circumstances, by the stimulus of external bodies, by pain or pleasure, by desire or aversion, or by the previous motions of other contracting fibres. In the first situation it is called the sensorial power of irritation, in the second the sensorial power of sensation, in the third the sensorial power of volition, and in the fourth the sensorial power of association. Many parts of the body are excited into perpetual action, as the sanguiferous vessels consisting of the heart, arteries, and veins; others into nearly perpetual action, as the conglomerate and capillary glands; and others into actions still somewhat less frequent, as the alimentary canal, and the lacteal and lymphatic absorbents with their conglobate glands: all these are principally actuated by the sensorial powers of irritation, and of association; but in some degree or at some times by those of sensation, and even of volition. There are three kinds of stimulus, which may easily be occasionally diminished, that of heat on the skin, of food in the stomach, and of the oxygenous part of the atmosphere, which mixes with the blood in respiration, and stimulates the heart and arteries. 2. When any parts, which are naturally excited into perpetual action by stimulus, become torpid or less active from decrease of that stimulus; there first occurs a decrease of the activity of the parts next catenated with them; thus going into cold water produces a torpor of the capillary vessels of the lungs, as is known by the difficult respiration, which immediately occurs; for the sensorial power of association, which naturally contributes to actuate the lungs, is now less excited by the decreased actions of the cutaneous vessels, with which they are catenated. This constitutes the cold fit of fever. There next occurs an accumulation of the sensorial power of irritation in the parts, which were torpid from defect of stimulus, as the cutaneous vessels for instance when exposed to cold air; and a similar accumulation of the sensorial power of association occurs in the parts which were catenated with the former, as the vessels of the lungs in the example above mentioned. Whence, if the subduction of stimulus has not been too great, so as to impair the health of the part, the activity of the irritative motions returns, even though the stimulus continues less than usual; and those of the associate motions become considerably increased, because these latter are now excited by the previous fibrous motions, which now act as strong or stronger than formerly, and have also acquired an accumulation of the sensorial power of association. This accounts for the curious event of our becoming warm in a minute or two after remaining in water of about 80 degrees of heat, as in the bath at Buxton; or in the cold air of a frosty morning of about 30 degrees of heat. But if the parts thus possessed of the accumulated sensorial powers of irritation and of association be exposed again to their natural quantity of stimulus, a great excess of activity supervenes; because the fibres, which possess accumulated irritation, are now excited by their usual quantity of stimulus; and those which possess accumulated association, are now excited by double or treble the quantity of the preceding irritative fibrous motions, with which they are catenated; this constitutes the hot fit of fever. Another important circumstance occurs, when the parts, which are torpid from decreased stimulus, do not accumulate a quantity of sensorial power sufficient for the purpose of renewing their own natural quantity of action; but are nevertheless not so torpid, as to have the life of the part impaired. In this situation the superabundance of the accumulated power of irritation contributes to actuate the associate motions next catenated with them. Thus, when a person breathes air with less oxygene than natural, as by covering his head in bed, and thus respiring the same atmosphere repeatedly, the heart and arteries become less active by defect of the stimulus of oxygene; and then the accumulation of sensorial power of irritation becomes instantly very great, as these organs are subject to perpetual and energetic action. This accumulation nevertheless is not so great as to renew their own activity under this defect of stimulus, but yet is in sufficient abundance to increase the associability of the next link of catenation, that is, to actuate the capillaries of the skin with great and perpetual increase of energy. This resembles continued fever with weak pulse; in which the accumulation of the sensorial power caused by the lessened motions of the heart and arteries, actuates the capillaries with increase of energy. 3. When the accumulation of the sensorial power of association, which is caused as above explained by deficient excitement owing to the lessened quantity of action of the irritative fibrous motions, with which the associate train is catenated, is not in quantity sufficient to renew the natural actions of the first link of an associate train of motions; it is nevertheless frequently so abundant as to actuate the next link of the associated train with unnatural energy by increasing its associability; and that in a still greater degree if that second link of the associated train was previously in a torpid state, that is, had previously acquired some accumulation of the sensorial power of association. This important circumstance of the animal economy is worthy our most accurate attention. Thus if the heart and arteries are deprived of their due quantity of the stimulus of oxygene in the blood, a weak and quick pulse ensues, with an accumulation of the sensorial power of irritation; next follows an increase of the action of the capillaries by the superabundance of this accumulated power of irritation; but there also exists an accumulation of the power of association in these acting capillaries, which is not now excited by the deficient actions of the heart and arteries; but which by its abundance contributes to actuate the next link of association, which is the sick stomach in the case related from Sydenham in Class IV. 1. 1. 2. and explained in this Supplement I. 4. And as this sick stomach was in a previous state of torpor, it might at the same time possess an accumulation of some sensorial power, which, if it was of association, would be thus more powerfully excited by the increased actions of the capillaries; which existed in consequence of the weak action of the heart and arteries. This also resembles in some respects the continued fevers with weak pulse, and with increased activity of the capillaries. 4. When a torpor of some irritative motions occurs from a previous exhaustion of the sensorial power of irritation by the action of some very great stimulus, it is long before any accumulation of the sensorial power of irritation is produced; as is experienced in the sickness and languor, which continues a whole day after a fit of drunkenness. But nevertheless there occurs an accumulation of the sensorial power of association in the first link of the associate train of motions, which is catenated with these torpid irritative ones; which accumulation is owing to deficient excitement of that sensorial power in the first link of the associate train. This first link therefore exists also in a less active or torpid state, but the accumulation of the sensorial power of association by its superabundance contributes to actuate the second link of the associate train with unnatural quantity of motion; and that though its own natural quantity of the power of association is not excited by the deficient action of preceding fibrous motions. When this happens to the stomach, as after its irritative motions have been much exerted from the unnatural stimulus of wine, or opium, or of contagious matter mixed with the saliva, a torpor or inactivity of it succeeds for a greater or less length of time; as no accumulation of the sensorial power of irritation can occur, till the natural quantity, which has been previously expended, is first restored. Then the heart and arteries which are next in catenation, become less active from the want of sufficient excitement of the sensorial power of association, which previously contributed to actuate them. This sensorial power of association therefore becomes accumulated, and by its superabundance contributes to actuate the link next in association, which has thus acquired so great a degree of associability, as to overbalance the less quantity of the excitement of it by the torpid action of the previous or first associate link. This happens to the capillaries, when the heart and arteries are affected as above by the torpor of the stomach, when it is occasioned by previous great expenditure of its sensorial power, and thus constitutes fever with weak pulse, which is here termed inirritative fever, typhus mitior. 5. When a deficiency of stimulus is too great or too long continued, so as to impair the life of the part, no further accumulation of sensorial power occurs; as when the skin is long exposed to cold and damp air. In that case the link in catenation, that is, the first of the associate train, is rendered torpid by defect of excitement of its usual quantity of the sensorial power of association, and from there being no accumulation of the sensorial power of irritation to increase its associability, and thus to contribute to actuate it by overbalancing the defect of the excitement of its association. Thus on riding long and slowly on a cold and damp day, the exhalation of the vapour, which is impinged on the skin, as the traveller proceeds, carries away his warmth faster, than it is generated within the system; and thus the capillaries of the skin have their actions so much impaired after a time, that no accumulation of the sensorial power of irritation occurs; and then the stomach, whose motions are catenated with those of the capillaries, ceases to act from the deficient excitement of the power of association; and indigestion and flatulency succeed, instead of the increased digestion and hunger, which occur, when the cutaneous capillaries are exposed to a less degree of cold, and for a shorter time. In which latter situation the accumulation of the sensorial power of irritation increases by its superabundance the associability of the fibres of the stomach, so as to overbalance the defect of the excitement of their association. 6. The stomach is affected secondarily in fevers with strong pulse, as in those with weak pulse it is affected primarily. To illustrate this doctrine I shall relate the following case of Mr. Y----. He was a young man rather intemperate in the use of wine or beer, and was seized with a cold fit, and with a consequent hot one with strong pulse; on examining his hypochondrium an oblong tumour was distinctly felt on the left side of the stomach, which extended six or eight inches downward, and was believed to be a tumour of the spleen, which thus occasioned by its torpor the cold fit and consequent hot fit of fever with strong pulse. This fever continued, though with remissions, for two or three weeks; and the patient repeatedly lost blood, used cathartics with calomel and sena, and had frequent antimonial and saline medicines. And after he was much weakened by evacuations, the peruvian bark and small doses of steel removed the fever, but the tumour remained many years during the remainder of his life. In this case the tumour of the spleen was occasioned by the torpor of the absorbent vessels; while the secerning vessels continued somewhat longer to pour their fluids into the cells of it. Then the inactivity of this viscus affected the whole system with torpor by the deficient excitement of the sensorial power of association, which contributes along with the irritation caused by their specific stimuli to actuate the whole sanguiferous, secerning, and absorbent vessels; and along with these the stomach, which possesses perhaps greater mobility, or promptitude to torpor or to orgasm, than any other part. And after a time all these parts recover their actions by the accumulation of their sensorial power of association. But the spleen not recovering its action from the accumulation of its power of irritation, as appeared from the continuance of the tumor, still affects the stomach by its defective irritative motions ceasing to excite the association, which ought to contribute to actuate it. Hence the stomach continues torpid in respect to its motions, but accumulates its power of association; which is not excited into action by the defective motions of the spleen; this accumulation of the sensorial power of association now by its superabundance actuates the next link of associate motions, which consists of the heart and arteries, into greater energy of action than natural, and thus causes fever with strong pulse; which, as it was supposed to be most frequently excited by increase of irritation, is called irritative fever or synocha. Similar to this in the small pox, which is given by inoculation, the stomach is affected secondarily, when the fever commences; and hence in this small-pox the pulsations of the heart and arteries are frequently stronger than natural, but never weaker, for the reasons above given. Whereas in that small-pox, which is caused by the stomach being primarily affected, by the contagious matter being swallowed with the saliva, whether the tonsils are at the same time affected or not, the pulsations of the heart and arteries become weak, and the inirritative fever is produced, as explained above, along with the confluent small-pox. This unfolds the cause of the mildness of the inoculated small-pox; because in this disease the stomach is affected secondarily, whereas in the natural small-pox it is frequently affected primarily by swallowing the contagious matter mixed with saliva. In the measles I suppose the contagious matter to be dissolved in the air, and therefore not liable to be mixed with the saliva; whereas the variolous matter is probably only diffused in the air, and thence more readily mixed with the saliva in the mouth during respiration. This difference appears more probable, as the small-pox I believe is always taken at a less distance from the diseased person than is necessary to acquire the measles. The contagion of the measles affects the membranes of the nostrils, and the secretion of tears in consequence, but never I suspect the stomach primarily, but always secondarily; whence the pulsation of the heart and arteries is always stronger than natural, so as to bear the lancet at any period of the disease. The great mildness sometimes, and fatality at other times, of the scarlet fever may depend on the same circumstance; that is, on the stomach being primarily or secondarily affected by the contagious matter, observing that the tonsils may be affected at the same time with the stomach. Should this prove to be the case, which future observations must determine, what certain advantage must arise from the inoculation of this disease! When it is received by the skin primarily I suppose no sore throat attends it, nor fever with weak pulse; when it is received by the stomach primarily, the tonsils are affected at the same time, and the torpor of the stomach produces inirritative fever, and the mortification of the tonsils succeeds. We may hence conclude, that when the torpor of the stomach is either owing to defect of stimulus, which is not so great as to impair the life of the part, as in moderate hunger, or in swallowing iced water, or when its torpor is induced by its catenation or association with other torpid parts, as in the commencement of intermittent fevers, and inoculated small-pox, that the subsequent action of the heart and arteries is generally increased, producing irritative fever. Which is owing to the accumulation, of the sensorial power of irritation in one case, and of association in the other, contributing to actuate the next link of the catenated or associated motions. But when the torpor of the stomach is induced by previous exhaustion of its sensorial powers of irritation or of association by continued violent action, as by the stimulus of digitalis, or of contagious matter, or after intoxication from wine or opium, a weaker action of the heart and arteries succeeds, because there is no accumulation of sensorial power, and a deficient excitement of association. And finally, as this weak action of the heart and arteries is not induced by exhaustion of sensorial power, but by defect of the excitement of association, the accumulation of this power of association increases the action of the capillaries, and thus induces inirritative fever. 7. When any part of the system acts very violently in fevers, the sensorial power of sensation is excited, which increases the actions of the moving system; whereas the pain, which arises from decreased irritative motions, as in hemicrania, seems to exhaust a quantity of sensorial power, without producing or increasing any fibrous actions. When the stomach is primarily affected, as in inirritative fevers from contagion, and in such a manner as to occasion pain, the action of the capillaries seems to be increased by this additional sensorial power of sensation, whence extensive inflammation or mortification; but when the stomach and consequently the heart and arteries continue their torpidity of action; as in confluent small-pox, and fatal scarlatina; this constitutes sensitive inirritative fever, or typhus gravior. But when the stomach is secondarily affected, if the sensorial power of sensation is excited, as in pleurisy or peripneumony, the actions of the heart and arteries are violently increased, and of all the moving system along with them. Thus the peripneumony is generally induced by the patient respiring very cold air, and this especially after being long confined to warm air, or after being much fatigued and heated by excessive labour or exercise. For we can cover the skin with more clothes, when we feel ourselves cold; but the lungs not having the perception of cold, we do not think of covering them, nor have the power to cover them, if we desired it; and the torpor, thus produced is greater, or of longer duration, in proportion to the previous expenditure of sensorial power by heat or exercise. This torpor of the lungs affects the skin with shuddering, and the stomach is also secondarily affected; next follows the violent action of the lungs from the accumulation of the power of irritation, and an inflammation of them follows this violent action. While the stomach recovers its activity by the increase of the excitement of the sensorial power of association, and along with it the heart and arteries, and the whole moving system. Hence this inflammation occurs during the hot fit of fever, and no cold fit succeeds, because the excess of the sensorial power of sensation prevents a succeeding torpor. These new motions of certain parts of the system produce increased secretions of nutritious or organic mucus, which forms new vessels; these new vessels by their unusual motions produce new kinds of fluids; which are termed contagious, because they have the power, when introduced into a healthy body, of producing similar actions and effects, with or without fever, as in the small-pox and measles, or in the itch and venereal disease. If any of these contagious matters affect the stomach with torpor either by their stimulus immediately applied, or by its sympathy with the parts first diseased, a fever is produced with sickness and want of appetite; as in small-pox, and scarlatina. If the stomach is not affected by contagious matter, no fever succeeds, as in itch, tinea, syphilis. All these contagious matters are conceived to be harmless, till they have been exposed to the air, either openly or through a moist membrane; from which they are believed to acquire oxygene, and thence to become some kinds of animal acids. As the preparations of mercury cure venereal ulcers; as a quarter of a grain of sublimate dissolved in wine, and given thrice a day; this effect, seems to be produced either by its stimulating the absorbents in the ulcer to absorb the venereal matter before it has acquired oxygene; or by afterwards uniting with it chemically, and again depriving it of its acquired acidity. On either supposition it might probably be given with advantage in small-pox, and in all infectious diseases, both previous to their commencement, and during their whole progress. 8. The cold fits of intermittent fevers are caused by the torpor of some part owing to deficient irritation, and of the other parts of the system from deficient association. The hot fits are owing first to the accumulation of irritation in the part primarily affected, if it recovers its action, which does not always happen; and secondly to the accumulation of association in the other parts of the system, which during health are subject to perpetual action; and lastly also to the greater excitement of the power of association, when the part primarily affected recovers its irritability, and acts with greater energy than natural. The deficient secretions in the cold fit depend on the torpor of the glandular system; and the increased secretions in the hot fit on their more energetic action. The thirst in the cold fit is owing to the deficient absorption from the skin, cellular membrane, and bladder; the thirst in the hot fit is owing to the too great dissipation of the aqueous part of the blood. The urine is pale and in small quantity in the cold fit from deficient secretion of it, and from deficient absorption of its aqueous parts; it is high coloured, and sometimes deposits a sediment, in the hot fit from the greater secretion of it in the kidneys, and the greater absorption of its aqueous and saline part in the bladder. The dryness and scurf on the tongue and nostrils is owing to the increased heat of the air expired from the lungs, and consequent greater evaporation of the aqueous part of the mucus. The sweats appear in consequence of the declension of the hot fit, owing to the absorbent vessels of the skin losing their increased action sooner than the secerning ones; and to the evaporation lessening as the skin becomes cooler. The returns of the paroxysms are principally owing to the torpor of some less essential part of the system remaining after the termination of the last fit; and are also dependent on solar or lunar diurnal periods. The torpor of the part, which induces the cold paroxysm, is owing to deficient irritation occasioned either by the subduction of the natural stimuli of food, or water, or pure air, or by deficiency of external influences, as of heat, or of solar or lunar gravitation. Or secondly, in consequence of the exhaustion of sensorial power by great previous exertions of some parts of the system, as of the limbs by great labour or exercise, or of the stomach by great stimulus, as by contagious matter swallowed with the saliva, or by much wine or opium previously taken into it. Or lastly a torpor of a part may be occasioned by some mechanic injury, as by a compression of the nerves of the part, or of their origin in the brain; as the sitting long with one leg crossed over the other occasions numbness, and as a torpor of the stomach, with vomiting frequently precedes paralytic strokes of the limbs. As sleep is produced, either by defect of stimulus, or by previous exhaustion of sensorial power; so the accumulation of the sensorial power of volition in those muscles and organs of sense, which are generally obedient to it, awakens the sleeping person; when it has increased the quantity of voluntarity so much as to overbalance the defect of stimulus in one case, and the exhaustion of sensorial power in the other; which latter requires a much longer time of sleep than the former. So the cold paroxysm of fever is produced either by defect of stimulus, or by previous exhaustion of the sensorial power of some part of the system; and the accumulation of the sensorial power of irritation in that part renews the action of it, when it has increased its irritability so much as to overbalance the defect of stimulus in one case and the exhaustion of sensorial power in the other; which latter requires a much longer torpor or cold fit than the former. But in the cold paroxysm of fever besides the torpor of one part of the system from defect of irritation, the remainder of it becomes torpid owing to defect of excitement of the sensorial power of association by the lessened action of the part first affected. This torpor of the general system remains, till the accumulation of the sensorial power of association has increased the associability so much as to overbalance the defect of the excitement of association; then the torpor ceases, and if the first affected part has recovered its activity the other parts are all thrown into excess of action by their increased associability, and the hot fit of fever is produced. 9. In the continued fevers with strong pulse the stomach is affected secondarily, and thus acts feebly from deficient excitement of the power of association; but the accumulation of the power of association thus produced in an organ subject to perpetual and energetic action, is so great as to affect the next link of the associate train, which consists of the heart and arteries; these therefore are exerted perpetually with increase of action. In continued fevers with weak pulse the torpid stomach is affected primarily by previous exhaustion of its irritability by stimulus, as of contagious matter swallowed into it. The heart and arteries act feebly from deficient excitement of the power of association, owing to the torpor of the stomach, with which they are catenated; but the accumulation of the power of association, thus produced in organs subject to perpetual and energetic motion, is so great, as to affect the next link of the associate train; which consists of the capillaries of the skin or other glands; these therefore are exerted perpetually with great increase of action. The continued fevers with strong pulse terminate by the reduction or exhaustion of the sensorial power by violent action of the whole system; which is followed either by return of health with the natural quantity of irritability, and of associability, or by a total destruction of them both, and consequent death. In continued fevers with weak pulse the stomach remains torpid during the whole course of the fever; and at length by the recovery of its irritability and sensibility effects the cure of it. Which generally happens about the first, second, or third quarter of the lunar period, counted from the commencement of the disease, or continues a whole lunation, and sometimes more; which gave rise to what are termed critical days. See Sect. XXXVI. 4. on this subject. If the stomach does not recover from its torpor, the patient becomes emaciated, and dies exhausted by the continuance of the increased action of the capillaries and absorbents, and the want of nourishment. The cure of continued fever with weak pulse consists first in weakening the undue action of the capillaries of the skin by ablution with cold water from 32 to 80 degrees of heat; or by exposing them to cool air. Secondly by invigorating the actions of the stomach, by decreasing them for a time, and thence accumulating the power of irritation, as by an emetic, or by iced water, or iced wine. Or by increase of stimulus, as by bark, wine, opium, and food, in small quantities frequently repeated. Or by renewing the action of the stomach by slight electric shocks. Or by fomenting it frequently with water heated to 96 or 100 degrees. Or lastly by exciting its power of association with other parts of the system, as by a blister; which succeeds best when the extremities are cool; or by swinging, as in vertigo rotatoria. If by the stimulus of the Peruvian bark on the fibres of the stomach, they regain their due action, the heart and arteries also regain their due action; as their sensorial power of association is now excited, and expended as usual. And as there is then no accumulation of sensorial power in the heart and arteries, the capillaries cease to act with too great energy, and the fever is cured. Thirdly. If the heart and arteries could be themselves stimulated into greater action, although the stomach remained torpid, they might probably by expending a greater quantity of the sensorial power of irritation, prevent an accumulation of the sensorial power of association, (for these may possibly be only different modes of action of the spirit of animation,) and thus the too great action of the capillaries might be prevented and the fever cease. This new mode of cure might possibly be accomplished, if the patient was to breathe a gallon or two of pure or diluted oxygene gas frequently in a day; which by passing through the moist membranes of the lungs and uniting with the blood might render it more stimulant, and thus excite the heart and arteries into greater action. Fourthly. Greater energy might probably be given to the whole system, and particularly to those parts which act too feebly in fevers, as the stomach and the heart and arteries, if the action of the secerning vessels of the brain could be increased in energy; this is probably one effect of all those drugs, which when given in large quantity induce intoxication, as wine and opium. And when given with great caution in small quantities uniformly repeated, as from three drops to five of the tincture of opium, but not more, every six hours, I believe they supply an efficacious medicine in fevers with great arterial debility; and the more so, if the Peruvian bark be exhibited alternately every six hours along with them. There are other means of exciting the vessels of the brain into action; as first by decreasing the stimulus of heat by temporary cold fomentation; secondly, increasing the stimulus of heat by long continued warm fomentation; thirdly, by electricity, as very small shocks passed through it in all directions; and lastly by blisters on the head. All those require to be used with great caution, and especially where there exists an evident stupor, as the removing of that is I believe frequently injurious. See stupor, Class I. 2. 5. 10. The cure of fever with strong pulse consists in the repeated use of venesection, gentle cathartics, diluents; medicines producing sickness, as antimonials, digitalis; or the respiration of carbonated hydrogen; or by respiration of atmospheric air lowered by a mixture of hydrogen, azote, or carbonic acid gas, or by compressing the brain by whirling in a decumbent posture, as if lying across an horizontal mill-stone. See the former parts of this supplement for the methods of cure both of fevers with strong and weak pulse. 10. When any difficulty occurs in determining the weak pulse from the strong one, it may generally be assisted by counting its frequency. For when an adult patient lies horizontally in a cool room, and is not hurried or alarmed by the approach of his physician, nor stimulated by wine or opium, the strong pulse seldom exceeds 118 or 120 in a minute; and the weak pulse is generally not much below 130, and often much above that number. Secondly in sitting up in bed, or changing the horizontal to a perpendicular posture, the quickness of the weak pulse is liable immediately to increase 10 or 20 pulsations in a minute, which does not I believe occur in the strong pulse, when the patient has rested himself after the exertion of rising. XVII. _Conclusion._ Thus have I given an outline of what may be termed the sympathetic theory of fevers, to distinguish it from the mechanic theory of Boerhaave, the spasmodic theory of Hoffman and of Cullen, and the putrid theory of Pringle. What I have thus delivered, I beg to be considered rather as observations and conjectures, than as things explained and demonstrated; to be considered as a foundation and a scaffolding, which may enable future industry to erect a solid and a beautiful edifice, eminent both for its simplicity and utility, as well as for the permanency of its materials,--which may not moulder, like the structures already erected, into the sand of which they were composed; but which may stand unimpaired, like the Newtonian philosophy, a rock amid the waste of ages! * * * * * ADDITIONS. * * * * * ADDITION I. At the end of the article Canities, in Class I. 2. 2. 11. please to add the following: As mechanical injury from a percussion, or a wound, or a caustic, is liable to occasion the hair of the part to become grey; so I suspect the compression of parts against each other of some animals in the womb is liable to render the hair of those parts of a lighter colour; as seems often to occur in black cats and dogs. A small terrier bitch now stands by me, which is black on all those parts, which were external, when she was wrapped up in the uterus, teres atque rotunda; and those parts white, which were most constantly pressed together; and those parts tawny, which were generally but less constantly pressed together. Thus the hair of the back from the forehead to the end of the tail is black, as well as that of the sides, and external parts of the legs, both before and behind. As in the uterus the chin of the whelp is bent down, and lies in contact with the fore part of the neck and breast; the tail is applied close against the division of the thighs behind; the inside of the hinder thighs are pressed close to the sides of the belly, all these parts have white hairs. The fore-legs in the uterus lie on each side of the face; so that the feet cover part of the temples, and compress the prominent part of the upper eye-brows, but are so placed as to defend the eye-balls from pressure; it is curious to observe, that the hair of the sides of the face, and of the prominent upper eye-brows, are tawny, and of the inside of the feet and legs, which covered them; for as this posture admitted of more change in the latter weeks of gestation, the colour of these parts is not so far removed from black, as of those parts, where the contact or compression was more uniform. Where this uterine compression of parts has not been so great as to render the hair white in other animals, it frequently happens, that the extremities of the body are white, as the feet, and noses, and tips of the ears of dogs and cats and horses, where the circulation is naturally weaker; whence it would seem, that the capillary glands, which form the hair, are impeded in the first instance by compression, and in the last by the debility of the circulation in them. See Class I. 1. 2. 15. This day, August 8th, 1794, I have seen a negro, who was born (as he reports) of black parents, both father and mother, at Kingston in Jamaica, who has many large white blotches on the skin of his limbs and body; which I thought felt not so soft to the finger, as the black parts. He has a white divergent blaze from the summit of his nose to the vertex of his head; the upper part of which, where it extends on the hairy scalp, has thick curled hair, like the other part of his head, but quite white. By these marks I supposed him to be the same black, who is described, when only two years old, in the Transactions of the American Philosophical Society, Vol. II. page 292, where a female one is likewise described with nearly similar marks. The joining of the frontal bones, and the bregma, having been later than that of the other sutures of the cranium, probably gave cause to the whiteness of the hair on these parts by delaying or impeding its growth. ADDITION II. The following extract from a letter of Dr. Beddoes on hydrocephalus internus, I esteem a valuable addition to the article on that subject at Class I. 2. 3. 12. "Master L----, aged 9 years, became suddenly ill in the night about a week before I saw him. On the day before the attack, he had taken opening medicines, and had bathed afterwards. He had complained of violently acute pain in his head, shrieked frequently, ground his teeth hard, could not bear to have his head raised from the pillow, and was torpid or deaf. His tongue was white, pulse 110 in the evening and full. As yet the pupil of the eye was irritable, and he had no strabismus. He had been bled with leeches about the head, and blistered. I directed mercurial inunction, and calomel from 3 to 6 grains to be taken at first every six, and afterwards every three hours. This plan produced no sensible effect, and the patient died on the 18th day after the seizure. He had convulsion fits two days preceding his death, and the well-known symptoms of hydrocephalus internus all made their appearance. From what I had seen and read of this disease, I believed it to belong to inflammations, and at an earlier period I should be tempted to bleed as largely as for pneumonia. The fluid found after death in the ventricules of the brain I impute to debility of the absorbents induced by inflammation. My reasons are briefly these; 1. The acuteness of the pain. 2. The state of the pulse. In the above case for the first 9 or 10 days it did not exceed 110, and was full and strong. 3. To find out whether any febrile alternations took place, Master L.'s feet were frequently felt, and they were found at times cold, and at other times of a dry heat. I have many times seen this disease, but the patients were too young, or too far advanced, to inform me, whether they had chillness succeeded by heat at its onset. 4. The disorders to which the young are more peculiarly liable afford a presumption, that hydrocephalus internus is an inflammatory disease; and this is confirmed by the regularity of the period, within which it finishes its course. And lastly, does it not happen more frequently than is suspected from external injury? I have just now been well informed, that Dr. Rush has lately cured five out of six patients by copious bleedings. I relate here the reasons for an opinion without pretending to a discovery. Something like this doctrine may be found in certain modern publications, but it is delivered in that vague and diffuse style, which I trust your example will banish from medical literature." Clifton, near Bristol, _July 28, 1795_. To this idea of Dr. Beddoes may be added, that the hydrocele generally succeeds an injury, and consequent inflammation of the bag, which contains it. And that other dropsies, which principally attend inebriates, are consequent to too great action of the mucous membranes by the stimulus of beer, wine, and spirits. And lastly, that as these cases of hydrocephalus end so fatally, a new mode of treating them is much to be desired, and deserves to be seriously attended to. ADDITION III. ON VERTIGO. _To be placed after the additional Note at the end of Vol. I. on this Subject._ Having reperused the ingenious Essay of Dr. Wells on Single Vision, and his additional observations in the Gentleman's Magazine on the apparent retrogression of objects in vertigo, I am induced to believe, that this apparent retrogression of objects is not always owing to the same cause. When a person revolves with his eyes closed, till he becomes vertiginous, and then stands still without opening them, he seems for a while to go forward in the same direction. This hallucination of his ideas cannot be owing to ocular spectra, because, as Dr. Wells observes, no such can have been formed; but it must arise from a similar continuance or repetition of ideas belonging to the sense of touch, instead of to the sense of vision; and should therefore be called a tangible, not a visual, vertigo. In common language this belief of continuing to revolve for some time, after he stands still, when a person has turned round for a minute in the dark, would be called a deception of imagination. Now at this time if he opens his eyes upon a gilt book, placed with other books on a shelf about the height of his eye, the gilt book seems to recede in the contrary direction; though his eyes are at this time kept quite still, as well as the gilt book. For if his eyes were not kept still, other books would fall on them in succession; which, when I repeatedly made the experiment, did not occur; and which thus evinces, that no motion of the eyes is the cause of the apparent retrocession of the gilt book. Why then does it happen?--Certainly from an hallucination of ideas, or in common language the deception of imagination. The vertiginous person still imagines, that he continues to revolve forwards, after he has opened his eyes; and in consequence that the objects, which his eyes happen to fall upon, are revolving backward; as they would appear to do, if he was actually turning round with his eyes open. For he has been accustomed to observe the motions of bodies, whether apparent or real, so much more frequently by the eye than by the touch; that the present belief of his gyration, occasioned by the hallucinations of the sense of touch, is attended with ideas of such imagined motions of visible objects, as have always accompanied his former gyrations, and have thus been associated with the muscular actions and perceptions of touch, which occurred at the same time. When the remains of colours are seen in the eye, they are termed ocular spectra; when remaining sounds are heard in the ear, they may be called auricular murmurs; but when the remaining motions, or ideas, of the sense of touch continue, as in this vertigo of a blindfolded person, they have acquired no name, but may be termed evanescent titillations, or tangible hallucinations. Whence I conclude, that vertigo may have for its cause either the ocular spectra of the sense of vision, when a person revolves with his eyes open; or the auricular murmurs of the sense of hearing, if he is revolved near a cascade; or the evanescent titillations of the sense of touch, if he revolves blindfold. All these I should wish to call vanishing ideas, or sensual motions, of those organs of sense; which, ideas, or sensual motions, have lately been associated in a circle, and therefore for a time continue to be excited. And what are the ideas of colours, when they are excited by imagination or memory, but the repetition of finer ocular spectra? What the idea of sounds, but the repetition of finer auricular murmurs? And what the ideas of tangible objects, but the repetition of finer evanescent titillations? The tangible, and the auricular, and the visual vertigo, are all perceived by many people for a day or two after long travelling in a boat or coach; the motions of the vessel, or vehicle, or of the surrounding objects, and the noise of the wheels and oars, occur at intervals of reverie, or at the commencement of sleep. See Sect. XX. 5. These ideas, or sensual motions, of sight, of hearing, and of touch, are succeeded by the same effects as the ocular spectra, the auricular murmurs, and the evanescent titillations above mentioned; that is, by a kind of vertigo, and cannot in that respect be distinguished from them. Which is a further confirmation of the truth of the doctrine delivered in Sect. III. of this work, that the colours remaining in the eyes, which are termed ocular spectra, are ideas, or sensual motions, belonging to the sense of vision, which for too long a time continue their activity. ADDITION IV. OF VOLUNTARY MOTIONS. A correspondent acquaints me, that he finds difficulty in understanding how the convulsions of the limbs in epilepsy can be induced by voluntary exertions. This I suspect first to have arisen from the double meaning of the words "involuntary motions;" which are sometimes used for those motions, which are performed without the interference of volition, as the pulsations of the heart and arteries; and at other times for those actions, which occur, where two counter volitions oppose each other, and the stronger prevails; as in endeavouring to suppress laughter, and to stop the shudderings, when exposed to cold. Thus when the poet writes, ------video meliora, proboque, Deteriora sequor.---- The stronger volition actuates the system, but not without the counteraction of unavailing smaller ones; which constitute deliberation. A second difficulty may have arisen from the confined use of the words "to will," which in common discourse generally mean to choose after deliberation; and hence our will or volition is supposed to be always in our own power. But the will or voluntary power, acts always from motive, as explained in Sect. XXXIV. 1. and in Class IV. 1. 3. 2. and III. 2. 1. 12. which motive can frequently be examined previous to action, and balanced against opposite motives, which is called deliberation; at other times the motive is so powerful as immediately to excite the sensorial power of volition into action, without a previous balancing of opposite motives, or counter volitions. The former of these volitions is exercised in the common purposes of life, and the latter in the exertions of epilepsy and insanity. It is difficult _to think without words_, which however all those must do, who discover new truths by reasoning; and still more difficult, when the words in common use deceive us by their twofold meanings, or by the inaccuracy of the ideas, which they suggest. ADDITION V. OF FIGURE. I feel myself much obliged by the accurate attention given to the first volume of Zoonomia, and by the ingenious criticisms bestowed on it, by the learned writers of that article both in the Analytical and English Reviews. Some circumstances, in which their sentiments do not accord with those expressed in the work, I intend to reconsider, and to explain further at some future time. One thing, in which both these gentlemen seem to dissent from me, I shall now mention, it is concerning the manner, in which we acquire the idea of figure; a circumstance of great importance in the knowledge of our intellect, as it shews the cause of the accuracy of our ideas of motion, time, space, number, and of the mathematical sciences, which are concerned in the mensurations or proportions of figure. This I imagine may have in part arisen from the prepossession, which has almost universally prevailed, that ideas are immaterial beings, and therefore possess no properties in common with solid matter. Which I suppose to be a fanciful hypothesis, like the stories of ghosts and apparitions, which have so long amused, and still amuse, the credulous without any foundation in nature. The existence of our own bodies, and of their solidity, and of their figure, and of their motions, is taken for granted in my account of ideas; because the ideas themselves are believed to consist of motions or configurations of solid fibres; and the question now proposed is, how we become acquainted with the figures of bodies external to our organs of sense? Which I can only repeat from what is mentioned in Sect. XIV. 2. 2. that if part of an organ of sense be stimulated into action, as of the sense of touch, that part so stimulated into action must possess figure, which must be similar to the figure of the body, which stimulates it. Another previous prepossession of the mind, which may have rendered the manner of our acquiring the knowledge of figure less intelligible, may have arisen from the common opinion of the perceiving faculty residing in the head; whereas our daily experience shews, that our perception (which consists of an idea, and of the pleasure or pain it occasions) exists principally in the organ of sense, which is stimulated into action; as every one, who burns his finger in the candle, must be bold to deny. When an ivory triangle is pressed on the palm of the hand, the figure of the surface of the part of the organ of touch thus compressed is a triangle, resembling in figure the figure of the external body, which compresses it. The action of the stimulated fibres, which constitute the idea of hardness and of figure, remains in this part of the sensorium, which forms the sense of touch; but the sensorial motion, which constitutes pleasure or pain, and which is excited in consequence of these fibrous motions of the organ of sense, is propagated to the central parts of the sensorium, or to the whole of it; though this generally occurs in less degree of energy, than it exists in the stimulated organ of sense; as in the instance above mentioned of burning a finger in the candle. Some, who have espoused the doctrine of the immateriality of ideas, have seriously doubted the existence of a material world, with which only our senses acquaint us; and yet have assented to the existence of spirit, with which our senses cannot acquaint us; and have finally allowed, that all our knowledge is derived through the medium of our senses! They forget, that if the spirit of animation had no properties in common with matter, it could neither affect nor be affected by the material body. But the knowledge of our own material existence being granted, which I suspect few rational persons will seriously deny, the existence of a material external world follows in course; as our perceptions, when we are awake and not insane, are distinguished from those excited by sensation, as in our dreams, and from those excited by volition or by association as in insanity and reverie, by the power we have of comparing the present perceptions of one sense with those of another, as explained in Sect. XIV. 2. 5. And also by comparing the tribes of ideas, which the symbols of pictures, or of languages, suggest to us, by intuitive analogy with our previous experience, that is, with the common course of nature. See Class III. 2. 2. 3. on Credulity. ADDITION VI. _Please to add the following in page 14, after line 20._ _Cold and hot Fit._ As the torpor, with which a fit of fever commences, is sometimes owing to defect of stimulus, as in going into the cold-bath; and sometimes to a previous exhaustion of the sensorial power by the action of some violent stimulus, as after coming out of a hot room into cold air; a longer time must elapse, before there can be a sufficient accumulation of sensorial power to produce a hot fit in one case than in the other. Because in the latter case the quantity of sensorial power previously expended must be supplied, before an accumulation can begin. The cold paroxysm commences, when the torpor of a part becomes so great, and its motions in consequence so slow or feeble, as not to excite the sensorial power of association; which in health contributes to move the rest of the system, which is catenated with it. And the hot fit commences by the accumulation of the sensorial power of irritation of the part first affected, either so as to counteract its deficient stimulus, or its previous waste of sensorial power; and it becomes general by the accumulation of the sensorial power of association; which is excited by the renovated actions of the part first affected; or becomes so great as to overbalance the deficient excitement of it. On all these accounts the hot fit cannot be supposed to bear any proportion to the cold one in length of time, though the latter may be the consequence of the former. See Suppl. I. 16. 8. ADDITION VII. ON WARMTH. _To be added at the end of the Species Sudor Calidus, in Class I. 1. 2. 3._ When the heat of the body in weak patients in fevers is increased by the stimulus of the points of flannel, a greater consequent debility succeeds, than when it is produced by the warmth of fire; as in the former the heat is in part owing to the increased activity of the skin, and consequent expenditure of sensorial power; whereas in the latter case it is in part owing to the influx of the fluid matter of heat. So the warmth produced by equitation, or by rubbing the body and limbs with a smooth brush or hand, as is done after bathing in some parts of the East, does not expend nearly so much sensorial power, as when the warmth is produced by the locomotion of the whole weight of the body by muscular action, as in walking, or running, or swimming. Whence the warmth of a fire is to be preferred to flannel shirts for weak people, and the agitation of a horse to exercise on foot. And I suppose those, who are unfortunately lost in snow, who are on foot, are liable to perish sooner by being exhausted by their muscular exertions; and might frequently preserve themselves by lying on the ground, and covering themselves with snow, before they were too much exhausted by fatigue. See Botan. Garden, Vol. II. the note on Barometz. ADDITION VIII. PUERPERAL FEVER. _To be added to Class II. 1. 6. 16._ A very interesting account of the puerperal fever, which was epidemic at Aberdeen, has been lately published by Dr. Alexander Gordon. (Robinson, London.) In several dissections of those, who died of this disease, purulent matter was found in the cavity of the abdomen; which he ascribes to an erysipelatous inflammation of the peritonæum, as its principal seat, and of its productions, as the omentum, mesentery, and peritonæal coat of the intestines. He believes, that it was infectious, and that the contagion was always carried by the accoucheur or the nurse from one lying-in woman to another. The disease began with violent unremitting pain of the abdomen on the day of delivery, or the next day, with shuddering, and very quick pulse, often 140 in a minute. In this situation, if he saw the patient within 12 or 24 hours of her seizure, he took away from 16 to 24 ounces of blood, which was always sizy. He then immediately gave a cathartic consisting of three grains of calomel, and 40 grains of powder of jalap. After this had operated, he gave an opiate at night; and continued the purging and the opiate for several days. He asserts, that almost all those, whom he was permitted to treat in this manner early in the disease, recovered to the number of 50; and that almost all the rest died. But that when two or three days were elapsed, the patient became too weak for this method; and the matter was already formed, which destroyed them. Except that he saw two patients, who recovered after discharging a large quantity of matter at the navel. And a few, who were relieved by the appearance of external erysipelas on the extremities. This disease, consisting of an erysipelatous inflammation, may occasion the great debility sooner to occur than in inflammation of the uterus; which latter is neither erysipelatous, I suppose, nor contagious. And the success of Dr. Gordon's practice seems to correspond with that of Dr. Rush in the contagious fever or plague at Philadelphia; which appeared to be much assisted by early evacuations. One case I saw some time ago, where violent unceasing pain of the whole abdomen occurred a few hours after delivery, with quick pulse; which ceased after the patient had twice lost about eight ounces of blood, and had taken a moderate cathartic with calomel. This case induces me to think, that it might be safer and equally efficacious, to take less blood at first, than Dr. Gordon mentions, and to repeat the operation in a few hours, if the continuance of the symptoms should require it. And the same in respect to the cathartic, which might perhaps be given in less quantity, and repeated every two or three hours. Nor should I wish to give an opiate after the first venesection and cathartic; as I suspect that this might be injurious, except those evacuations had emptied the vessels so much, that the stimulus of the opiate should act only by increasing the absorption of the new vessels or fluids produced on the surfaces of the inflamed membranes. In other inflammations of the bowels, and in acute rheumatism, I have seen the disease much prolonged, and I believe sometimes rendered fatal, by the too early administration of opiates, either along with cathartics, or at their intervals; while a small dose of opium given after sufficient evacuations produces absorption only by its stimulus, and much contributes to the cure of the patient. We may have visible testimony of this effect of opium, when a solution of it is put into an inflamed eye; if it be thus used previous to sufficient evacuation, it increases the inflammation; if it be used after sufficient evacuation, it increases absorption only, and clears the eye in a very small time. I cannot omit observing, from considering these circumstances, how unwise is the common practice of giving an opiate to every woman immediately after her delivery, which must often have been of dangerous consequence. END OF THE SECOND PART. * * * * * ZOONOMIÆ AUCTORI _S.P.D._ AMICUS. * * * * * _CURRUS TRIUMPHALIS MEDICINÆ._ * * * * * Currus it Hygeiæ, Medicus movet arma triumphans, Undique victa fugit lurida turma mali.---- Laurea dum Phoebi viridis tua tempora cingit, Nec mortale sonans Fama coronat opus; Post equitat trepidans, repetitque Senectus in aurem, Voce canens stridulà, "sis memor ipse mori!" * * * * * INDEX OF THE CLASSES. A. Abortion, i. 2. 1. 14. ---- from fear, iv. 3. 1. 7. ---- not from epilepsy, iii. 1. 1. 7. ---- not from hepatitis, ii. 1. 2. 12. Absorption of solids, i. 2. 2. 14. ---- of matter, ii. 1. 6. 2. and 6. ---- cellular, iv. 1. 1. 6. ---- from the lungs, iv. 3. 1. 5. Suppl. i. 8. 6. Abstinence of young ladies, ii. 2. 2. 1. Accumulation of feces, ii. 2. 2. 7. Acupuncture, iii. 1. 1. 8. Adipsia, ii. 2. 2. 2. Ægritudo ventriculi, i. 2. 4. 4. ---- See Sickness. Agrypnia. See Vigilia. Ague-cakes, Suppl. i. 2. 3. Alum in ulcers of the mouth, ii. 1. 3. 1. Ambition, iii. 1. 2. 9. Amaurosis, i. 2. 5. 5. Anasarca of the lungs, i. 2. 3. 16. Anger, iii. 1. 2. 17. Anger, tremor of, iv. 2. 3. 4. ---- blush of, iv. 2. 3. 5. Angina. See Tonsillitis. ---- pectoris. See Asthma painful. Anhelitus, ii. 1. 1. 4. Anhelatio spasmodica, i. 3. 3. 3. Annulus repens, ii. 1. 5. 10. Anorexia, ii. 2. 2. 1. ---- maniacalis, Suppl. i. 14. 3. ---- epileptica, ii. 2. 2. 1. iii. 1. 1. 7. Apepsia, i. 3. 1. 3. Suppl. i. 8. 11. Aphtha, ii. 1. 3. 17. Apoplexy, iii. 2. 1. 16. Appetite defective, ii. 2. 2. 1. ---- depraved, iii. 1. 2. 19. ---- from abstinence, ii. 2. 2. 1. ---- destroyed, iii. 1. 2. 20. ---- from epilepsy, ii. 2. 2. 1. Arm, pain of, iv. 2. 2. 13. ---- palsy of, iii. 2. 1. 4. Arsenic in tooth-ach, i. 2. 4. 12. ---- in head-ach, i. 2. 4. 11. Arthrocele, ii. 1. 4. 17. Arthropuosis, ii. 1. 4. 18. Arthritis. See Gout. Ascarides, i. 1. 4. 12. iv. 1. 2. 9. Ascites, i. 2. 3. 13. Associations affected four ways, iv. 1. 1. G. ---- how produced, iv. 1. 1. H. ---- distinct from catenations, iv. 1. 1. A. ---- three kinds of, iv. 1. 1. B. ---- tertian, iv. 1. 1. K. ---- of the fauces and pubis, iv. 1. 2. 7. ---- sensitive, a law of, iv. 2. 2. 2. ---- sensitive iv. 2. 1. ---- accumulates, Suppl. i. 8. 3. i. 11. 4. Asthma humoral, ii. 1. 1. 7. i. 3. 2. 8. ---- of infants, i. 1. 3. 4. ---- convulsive, iii. 1. 1. 10. ---- painful, iii. 1. 1. 11. Auditus acrior, i. 1. 5. 2. ---- imminutus, i. 2. 5. 6. Azote, Suppl. i. 9. 3. i. 11. 6. B. Bandages, ill effect of, ii. 1. 1. 12. ---- promote absorption, i. 1. 3. 13. Bath, cold, i. 2. 2. 1. ---- warm, Addit. vii. Beauty, iii. 1. 2. 4. ---- loss of, iii. 1. 2. 12. Bile-duct, pain of, iv. 2. 2. 4. Bile crystalized, i. 1. 3. 8. Bitter taste, i. 1. 3. 1. ---- not from bile, i. 1. 3. 1. Bleeding. See Hæmorrhage. Bladder, distention of, ii. 2. 2. 6. ---- stone of, i. 1. 3. 10. ---- catarrh of, ii. 1. 4. 11. Blindness, i. 2. 5. 5. Blush of anger, iv. 2. 3. 5. Suppl. i. 12. 7. ---- of guilt, iv. 2. 3. 6. Suppl. i. 12. 7. Bones, innutrition of, i. 2. 2. 14. ---- caries of, ii. 1. 4. 19. Borborigmus, i. 3. 1. 9. Bougies, ii. 1. 4. 11. Brachiorum paralysis, iii. 2. 1. 4. Brain stimulated, Suppl. i. 16. 9. Bronchocele, i. 2. 3. 20. Burns, i. 1. 3. 13. Butterflies, experiment on, i. 1. 2. 3. C. Cacositia, iii. 1. 2. 20. Calculi productio, i. 1. 3. 9. ii. 1. 2. 14. ---- renis, i. 1. 3. 9. iv. 2. 3. 3. ---- vesicæ, i. 1. 3. 10. iv. 2. 2. 2. Callico shirts, i. 1. 2. 3. Callus, i. 2. 2. 12. Canities. See Hair grey. Calor febrilis, i. 1. 2. 1. Calves fed on gruel, i. 1. 2. 5. ---- hydatides of, i. 2. 5. 4. Cancer, ii. 1. 4. 16. ii. 1. 6. 13. Cantharides, large dose of, iv. 2. 2. 2. Carbonic acid gas, Suppl. i. 9. 3. Cardialgia, i. 2. 4. 5. Carcinoma, ii. 1. 4. 16. ii. 1. 6. 13. Caries ossium, ii. 1. 4. 19. Cataract, i. 2. 2. 13. Catarrh, warm, i. 1. 2. 7. ---- cold, i. 2. 3. 3. ---- lymphatic, i. 3. 2. 1. ---- sensitive, ii. 1. 3. 5. ---- epidemic, ii. 1. 3. 6. ---- of dogs and horses, ii. 1. 3. 6. ---- from cold skin, iv. 1. 1. 5. ---- periodic, iv. 3. 4. 1. Catamenia, i. 2. 1. 11. iv. 2. 4. 7. Catalepsis, iii. 2. 1. 9. Cats, mumps of, ii. 1. 3. 4. Cephalæa frigida, i. 2. 4. 11. iv. 2. 2. 7. Charcoal tooth-powder, i. 2. 4. 12. Cheek, torpor of, iv. 2. 2. 1. Chicken pox, ii. 1. 3. 15. Chin-cough, ii. 1. 3. 8. Child-bed fever, ii. 1. 6. 16. Children, new born, ii. 1. 1. 12. ---- gripes and purging of, i. 1. 2. 5. Chlorosis, i. 2. 3. 10. Suppl. i. 8. 11. Chorea St. Viti, iv. 2. 3. 2. Citta, iii. 1. 2. 19. Clamor, iii. 1. 1. 3. Clavicular animals, ii. 1. 2. 6. Clavus hystericus, iv. 2. 2. 8. Claudicatio coxaria, i. 2. 2. 17. Cold in the head. See Catarrh. Colic, flatulent, i. 2. 4. 7. ---- from lead, i. 2. 4. 8. ---- hysteric, i. 2. 4. 7. iii. 1. 1. 8. Cold air in fevers, iii. 2. 1. 12. iv. 2. 4. 11. ---- effects of, iii. 2. 1. 17. ---- how to be used, iv. 1. 1. 4. Compassion, iii. 1. 2. 24. Consumption, ii. 1. 6. 7. Convulsion, iii. 1. 1. 5. ---- weak, iii. 1. 1. 5. ---- from bad air, iii. 1. 1. 5. ---- painful, iii. 1. 1. 6. iv. 2. 4. 5. Consternation, i. 1. 5. 11. Constipation, i. 1. 3. 5. ii. 2. 2. 7. Contagious matter of two kinds, ii. 1. 3. ---- is oxygenated, ii. 1. 5. ---- produces fever, how, Suppl. i. 16. 7. Cornea to perforate, i. 1. 3. 14. ---- scars of seen on milk, i. 1. 3. 14. Corpulency, i. 2. 3. 17. Coryza. See Catarrh. Costiveness, i. 1. 3. 5. ii. 2. 2. 7. Cough of drunkards, ii. 1. 1. 5. ---- hooping, ii. 1. 3. 8. ---- hepatic, iv. 2. 1. 8. ---- gouty, iv. 2. 1. 9. ---- periodic, iv. 2. 4. 6. iv. 3. 4. 2. ---- from cold feet, iv. 2. 1. 7. Cows, pestilence of, ii. 1. 3. 13. ---- bloody urine of, ii. 1. 3. 13. Cramp, iii. 1. 1. 13. ---- painful, iii. 1. 1. 14. ---- in diarrhoea, iv. 1. 2. 10. Crab-lice, i. 1. 4. 14. Credulity, iii. 2. 2. 3. Crines novi, i. 1. 2. 15. Croup, i. 1. 3. 4. ii. 1. 2. 4. ii. 1. 3. 3. Crusta lactea, ii. 1. 5. 12. Cutis arida, i. 1. 3. 6. Cynanche. See Tonsillitis. ---- parotidæa. See Parotitis. D. Darkness in fevers, i. 2. 5. 3. Deafness, two kinds of, i. 2. 5. 6. Debility, three kinds of, i. 2. 1. ---- and strength metaphors, i. 2. 1. Decussation of nerves, iii. 2. 1. 10. Deglutition, ii. 1. 1. 1. ---- involuntary, iv. 1. 3. 1. Dentition, i. 1. 4. 5. Dentium dolor a stridore, iv. 1. 2. 3. Descent of the uterus, i. 1. 4. 8. Diabetes, i. 3. 2. 6. ---- foul tongue in, i. 1. 3. 1. ---- irritative, iv. 3. 1. 1. ---- from fear, iv. 3. 1. 3. Diarrhoea warm, i. 1. 2. 5. ---- of infants, i. 1. 2. 5. ---- lymphatic, i. 3. 2. 4. ---- chyliferous, i. 3. 2. 5. ---- cold, i. 2. 3. 6. ---- rheumatic, iv. 1. 2. 16. ---- from fear, iv. 3. 1. 4. ---- from toothing, iv. 2. 2. 14. ---- in fevers, Suppl. i. 2. 4. ---- cure of, iv. 1. 1. f. Digestion increased by cold, iv. 1. 1. 4. ---- decreased by cold, iv. 2. 1. 6. Dilirium febrile, ii. 1. 7. 1. ---- of drunkenness, ii. 1. 7. 3. ---- maniacal, ii. 1. 7. 2. ---- in parotitis, iv. 1. 2. 19. Diluents, use of, ii. 1. 2. 1. Distention of the nipples, ii. 1. 7. 10. iv. 1. 2. 7. Diuretics useless in dropsy, i. 1. 3. 7. Dizziness. See Vertigo. Dogs, catarrh of, ii. 1. 3. 6. Dolor digiti sympathet, iv. 2. 2. 12. ---- ductus choledochi, iv. 2. 2. 4. ---- humeri in hepatitide, iv. 2. 2. 9. ---- pharyngis ab acido, iv. 2. 2. 5. ---- testium nephriticus, iv. 2. 2. 11. ---- urens, i. 1. 5. 10. Dracunculus, i. 1. 4. 13. Dreams, ii. 1. 7. 4. Dropsy of the brain, i. 2. 3. 12. ---- of the belly, i. 2. 3. 13. ---- of the chest, i. 2. 3. 14. ---- of the ovary, i. 2. 3. 15. ---- of the lungs, i. 2. 3. 16. ---- of the scrotum, i. 2. 3. 11. Dysentery, ii. 1. 3. 18. Dysmenorrhagia, i. 2. 1. 12. Dyspnoea from cold bath, iv. 2. 1. 5. ---- rheumatica, iv. 1. 2. 16. Dyspepsia, i. 3. 1. 3. ---- a frigore, iv. 2. 1. 6. Dysuria insensitiva, ii. 2. 2. 6. E. Ears, discharge behind, i. 1. 2. 9. ---- noise in them, iv. 2. 1. 15. Ear-ach, iv. 2. 2. 8. Ebrietas, i. 1. 1. 2. Education, iii. 2. 1. 8. iii. 1. 2. 24. ---- heroic, iii. 1. 2. 25. Egg boiled for inflamed eyes, ii. 1. 4. 1. ---- boiled soonest, Suppl. i. 7. ---- life of, iv. 1. 4. 1. Electric shocks, iv. 1. 4. 5. Electrized zinc and silver, i. 2. 5. 5. ---- in paralysis, ii. 1. 1. 9. ---- in scrophula, i. 2. 3. 21. ---- in hoarseness, iii. 2. 1. 5. Empyema, ii. 1. 6. 4. Enteralgia rheumatica, iv. 1. 2. 16. Enteritis, ii. 1. 2. 11. ---- superficialis, ii. 1. 3. 20. Epilepsy, iii. 1. 1. 7. iv. 3. 1. 6. ---- painful, iii. 1. 1. 8. iv. 2. 4. 4. ---- terminates with sleep, iii. 1. 1. ---- in parturition, iii. 1. 1. 7. ---- with indigestion, ii. 2. 2. 1. Epistaxis. See Hæmorraghia. Epoulosis. See Cicatrix. Erotomania, iii. 1. 2. 4. Eructation, voluntary, iv. 3. 3. 3. Eruption of small-pox, iv. 1. 2. 12. iv. 2. 2. 10. Erysipelas, iv. 1. 2. 17. ii. 1. 3. 2. iv. 2. 4. 10. ---- seldom suppurates, why, ii. 1. 3. 2. Esuries, i. 2. 4. 2. Evil, i. 2. 3. 21. Expectoration, warm, i. 1. 2. 8. ---- solid, i. 1. 3. 4. ---- cold, i. 2. 3. 4. Exsudation behind the ears, i. 1. 2. 9. Eyes, blue under the, i. 2. 2. 2. ii. 1. 4. 4. Eyelid inverted, cure of, ii. 1. 1. 8. ---- coloured with antimony, ii. 1. 4. 3. F. Face, pimpled, ii. 1. 4. 6. ---- red after meals, Suppl. i. 12. 7. ---- flushed after dinner, iv. 1. 1. 1. Fat people why short breathed, ii. 1. 1. 4. Fear, syncope from, i. 2. 1. 4. ---- abortion from, iv. 3. 1. 7. ---- produces absorption, ii. 1. 6. 4. ---- paleness in, iv. 3. 1. 5. ---- of death, iii. 1. 2. 14. ---- of hell, iii. 1. 2. 15. ---- of poverty, iii. 1. 2. 13. Feet cold produces heartburn. Suppl. i. 8. 5. ---- fetid, i. 1. 2. 14. ---- cold in small-pox, iv. 2. 2. 10. Fevers, five kinds, ii. 1. 2. Suppl. i. 1. 2. ---- irritative, i. 1. 1. 1. iv. 1. 1. 8. ---- inirritative, i. 2. 1. 1. iv. 2. 1. 19. Suppl. i. 1. 2. ---- sensitive, ii. 1. 6. 1. ---- sensitive irritated, ii. 1. 2. 1. ---- sensitive inirritated, ii. 1. 3. 1. ---- intermit, why, Suppl. i. ---- continue, why, Suppl. i. ---- periods of, iv. 2. 4. 11. ---- simple, Suppl. i. 1. ---- compound, Suppl. i. 2. ---- termination of cold fit, Suppl. i. 3. ---- return of cold fit, Suppl. i. 4. ---- sensation in, Suppl. i. 5. ---- circles of motions in, Suppl. i. 6. ---- cold and hot fits, Suppl. i. 7. ---- continued, Suppl. i. 8. ---- torpor of lungs in, Suppl. i. 9. 1. ---- not determinable in cold fit, i. 1. 1. 1. ---- frequency of pulse in, i. 1. 1. 1. ---- not an effort to cure, i. 1. 2. 3. ---- puerperal, ii. 1. 6. 16. i. 2. 4. 9. ---- from inclosed matter, ii. 1. 6. 2. ---- from aerated matter, ii. 1. 6. 6. ---- from contagious matter, ii. 1. 6. 11. ---- from contagious sanies, ii. 1. 6. 15. ---- torpor of the stomach, Suppl. i. 12. ---- case of, Suppl. i. 13. ---- termination of, Suppl. i. 14. ---- inflammation excited, Suppl. i. 15. ---- returns of, Suppl. i. 4. ---- when cold air in, Suppl. i. 2. 2. ---- sympathetic, theory of, Suppl. i. ---- duration of explained, Suppl. i. 2. 5. Fingers, playing with, iv. 1. 3. 4. ---- pain of, iv. 2. 2. 12. Fish live longer with injured brain, i. 2. 5. 10. Fistula in ano, ii. 1. 4. 10. ---- lacrymalis, ii. 1. 4. 9. ---- urethra, ii. 1. 4. 11. Flannel shirt in diarrhoea, iv. 1. 1. 3. ---- injurious in summer, i. 1. 2. 3. Fluor albus warm, i. 1. 2. 11. ---- cold, i. 2. 3. 7. Frigus febrile, i. 2. 2. 1. ---- chronicum, i. 2. 2. 1. G. Gall-stone, i. 1. 3. 8. Gangreen, ii. 1. 6. 17. Gargles, ii. 1. 3. 3. Gastritis, ii. 1. 2. 10. ---- superficialis, ii. 1. 3. 19. Genu tumor albus, i. 2. 3. 19. Gleet. See Gonorrhoea. Globus hystericus, i. 3. 1. 7. Gonorrhoea warm, i. 1. 2. 10. ---- cold, i. 2. 3. 8. Gout, iv. 1. 2. 15. iv. 2. 4. 9. ---- of the liver, ii. 1. 1. 7. ---- cases of, iv. 1. 2. 15. ---- cough, iv. 2. 1. 9. ---- of the stomach, i. 2. 4. 6. ---- hæmorrhage in, i. 1. 1. 4. Grace defined, iii. 1. 2. 4. Gravel distinguished from salts, i. 1. 3. 10. Gravitation, iv. 2. 4. Green-sickness. See Chlorosis. Grief, iii. 1. 2. 10. Gripes of children, i. 1. 2. 5. iv. 2. 1. 3. Gustus acrior, i. 1. 5. 4. ---- imminutus, i. 2. 5. 8. Gutta rosea, ii. 1. 4. 6. iv. 1. 2. 13. and 14. ---- serena, i. 2. 5. 5. H. Hæmorrhage arterial, i. 1. 1. 3. ---- of the lungs, i. 1. 1. 4. ---- of the nose, i. 1. 1. 5. ---- venous, i. 2. 1. 5. ---- of the rectum, i. 2. 1. 6. ---- of the kidnies, i. 2. 1. 7. ---- of the liver, i. 2. 1. 8. Hæmoptoe arterial, i. 1. 1. 4. ---- venous, i. 2. 1. 9. Hæmorrhois cruenta, i. 2. 1. 6. iv. 2. 4. 8. ---- alba, i. 1. 2. 12. Hair, grey, i. 2. 2. 11. ---- new, i. 1. 2. 15. ---- white by uterine pressure, Addit. i. Hallucination of sight, ii. 1. 7. 5. ---- of hearing, ii. 1. 7. 6. ---- maniacal, iii. 1. 2. 1. ---- studiosa, iii. 1. 2. 2. Harrogate water fact, i. 1. 4. 12. Head-ach. See Hemicrania and Cephalæa. Hearing acuter, i. 1. 5. 2. ---- diminished, i. 2. 5. 6. Heart-burn, i. 2. 4. 5. Heart stimulated, Suppl. i. 11. 7. i. 16. 9. Heat, animal, i. 1. 2. 1. i. 1. 2. 3. ---- sense of acuter, i. 1. 5. 6. ---- elemental, iv. 2. 4. ---- hectic lessened by swinging, iv. 2. 1. 10. ---- not perceived by the lungs, iii. 1. 1. 10. ---- not estimated by thermometers, Suppl. i. 7. ---- of the breath, Suppl. i. 2. 2. Hemicrania, iv. 2. 2. 8. iv. 2. 4. 3. ---- relieved by mercury, iv. 2. 2. 8. Hemiplegia, iii. 2. 1. 10. Hepatis tumor, i. 2. 3. 9. Hepatitis, ii. 1. 2. 12. ---- chronica, ii. 1. 4. 12. Herpes, ii. 1. 5. 8. ---- nephritica, iv. 1. 2. 11. Hiccough, ii. 1. 1. 6. iv. 1. 1. 7. Hip-joint injured, i. 2. 2. 17. Hoarseness, ii. 1. 3. 5. iii. 2. 1. 5. Horses, broken wind of, i. 2. 4. 9. Humectation of the body, iv. 1. 4. 7. Hunger, i. 2. 4. 2. Hydatides in calves, i. 2. 5. 4. Hydrocele, i. 2. 3. 11. Hydrocephalus inter, i. 2. 3. 12. i. 2. 5. 4. iii. 2. 1. 10. ---- from inflammation, Addit. ii. Hydrogene gas. Suppl. i. 9. 3. i. 11. 6. ---- in fevers, Suppl. i. 11. 6. i. 16. 9. Hydrothorax, i. 2. 3. 14. case of, iv. 2. 2. 13. Hydro-carbonate gas, Suppl. i. 9. 1. Suppl. i. 15. 3. Hydrops ovarii, i. 2. 3. 15. Hydrophobia, i. 3. 1. 11. iii. 1. 1. 15. iv. 1. 2. 7. Hypochondriasis, i. 2. 4. 10. Hysteralgia frigida, i. 2. 4. 17. Hysteria, i. 3. 1. 10. Suppl. i. 8. 11. ---- from fear, iv. 3. 1. 8. ---- from cold, iv. 3. 4. 3. ---- convulsions in, iii. 1. 1. 5. ---- laughter in, iii. 1. 1. 5. Hysteritis, ii. 1. 2. 16. I. Jactitatio, iii. 1. 1. 1. Jaundice, i. 1. 3. 8. i. 2. 4. 19. Icterus, i. 1. 3. 8. i. 2. 4. 19. Ileus, i. 3. 1. 6. ii. 1. 2. 11. Impotentia, ii. 2. 2. 3. Indigestion, i. 3. 1. 3. ---- See Anorexia and Apepsia. ---- from cold feet, iv. 2. 1. 6. Sup. i. 8. 5. Incubus, iii. 2. 1. 13. Infants, green stools of, i. 1. 2. 5. ---- new born, ii. 1. 1. 12. Inflammation of the eye, ii. 1. 2. 2. ---- superficial, ii. 1. 4. 1. ---- of the brain, ii. 1. 2. 3. ---- of the lungs, ii. 1. 2. 4. ---- superficial, ii. 1. 3. 7. ---- of the pleura, ii. 1. 2. 5. ---- of the diaphragm, ii. 1. 2. 6. ---- of the heart, ii. 1. 2. 7. ---- of the peritoneum, ii. 1. 2. 8. ---- of the mesentery, ii. 1. 2. 9. ---- of the stomach, ii. 1. 2. 10. ---- superficial, ii. 1. 3. 19. ---- of the bowels, ii. 1. 2. 11. ---- superficial, ii. 1. 3. 20. ---- of the liver, ii. 1. 2. 12. ---- chronical, ii. 1. 4. 12. ---- of the spleen, ii. 1. 2. 13. Sup. i. 16. 6. ---- of the kidnies, ii. 1. 2. 14. ---- of the bladder, ii. 1. 2. 15. ---- of the womb, ii. 1. 2. 16. ---- of the tonsils, ii. 1. 3. 3. ---- of the parotis, ii. 1. 3. 4. Inirritability of lacteals, i. 2. 3. 26. ---- of lymphatics, i. 2. 3. 27. ---- of the gall-bladder, i. 2. 4. 19. ---- of the kidney, i. 2. 4. 20. ---- of the spleen, Suppl. i. 16. 6. ---- vicissitudes of, i. 1. 1. Inoculation, ii. 1. 3. 9. Innutrition of bones, i. 2. 2. 14. Insanity, quick pulse in, iii. 1. 1. ---- from parturition, iii. 1. 2. ---- with fever, iii. 1. 2. ---- cure of, iii. 1. 2. ---- confinement in, iii. 1. 2. Insensibility, ii. 2. 1. 1. Ira, iii. 1. 2. 17. Ischias, ii. 1. 2. 18. i. 2. 4. 15. Issues, use of, i. 1. 2. 9. iii. 1. 1. 11. Itch, ii. 1. 5. 6. Itching, i. 1. 5. 9. ---- of the nose, iv. 2. 2. 6. L. Lacrymarum fluxus sym. iv. 1. 2. 1. Lameness of the hip, i. 2. 2. 17. Lassitude, iii. 2. 1. 1. Laughter, iv. 2. 3. 3. iii. 1. 1. 4. iv. 1. 3. 3. ---- See Risus. Leg, one shorter, i. 2. 2. 17. Lepra, ii. 1. 5. 3. Lethargus, iii. 2. 1. 14. Lethi timor, iii. 1. 2. 14. Lice, i. 1. 4. 15. Lientery, i. 2. 3. 6. Light debilitates in fevers, i. 2. 5. 3. Lingua arida, i. 1. 3. 1. iv. 2. 4. 11. Liver, torpor of, i. 2. 2. 6. ---- tumor of, i. 2. 3. 9. ---- inflamed, ii. 1. 2. 12. Lochia nimia, i. 2. 1. 13. Locked jaw, iii. 1. 1. 13. Love, sentimental, iii. 1. 2. 4. Lues venerea, ii. 1. 5. 2. ---- imaginaria, iii. 1. 2. 21. Lumbago, ii. 1. 2. 17. iii. 1. 1. 1. ---- cold, i. 2. 4. 16. Lumbricus, i. 1. 4. 10. Lunar influence on the solids, i. 2. 1. 11. Lungs, adhesions of, ii. 1. 2. 5. ---- not sensible to heat, iii. 1. 1. 10. Lusus digitorum invitus, iv. 1. 3. 4. M. Maculæ vultus, i. 2. 2. 10. Madness, mutable, iii. 1. 2. 1. Mammarum tumor, iv. 1. 2. 19. Mammularum tensio, iv. 1. 2. 6. i. 1. 4. 7. Mania mutabilis, iii. 1. 2. 1. Matter variolous, ii. 1. 3. 9. ---- contagious, ii. 1. 3. ii. 1. 6. 11. ---- inclosed, ii. 1. 6. 2. ---- oxygenated, ii. 1. 6. 6. ---- sanious, ii. 1. 6. 15. Measles, ii. 1. 3. 10. Membranes, what, iv. 1. 2. Menorrhagia, i. 2. 1. 11. Mercury crude, as a clyster, i. 3. 1. 6. ---- in all contagions, Suppl. i. 16. 7. ---- in vertigo, iv. 2. 1. 11. Miliaria, ii. 1. 3. 12. Milk new, for children, i. 1. 2. 5. ---- old, induces costiveness, ii. 2. 2. 7. Milk-crust, ii. 1. 5. 12. Miscarriage. See Abortion. Mæror, iii. 1. 2. 10. Mobility, iv. 1. 2. ---- of the skin, Suppl. i. 7. Mollities ossium, i. 2. 2. 14. Moon, effect of, iv. 2. 4. Morbilli. See Rubeola. Mortification, ii. 1. 6. 17. Morpiones, i. 1. 4. 14. Mucus diminished, i. 2. 2. 4. ---- of the throat cold, i. 2. 3. 1. ---- of the bowels, i. 2. 3. 6. i. 1. 2. 12. ---- of the lungs, i. 1. 3. 4. ---- forms stones, i. 1. 3. 9. ---- distinguished from pus, ii. 1. 6. 6. Mumps, ii. 1. 3. 4. Murmur aurium, iv. 2. 1. 15. Muscæ volitantes, i. 2. 5. 3. N. Nails, biting of, iv. 1. 3. 5. Nares aridi, i. 1. 3. 3. Nausea, dry, i. 2. 4. 3. ---- humid, i. 3. 2. 3. ---- ideal, iv. 3. 2. 1. ---- from conception, iv. 3. 2. 2. Navel-string of infants, ii. 1. 1. 12. ---- cut too soon, ii. 1. 1. 12. Neck thickens at puberty, iv. 1. 2. 7. Neck-swing, i. 2. 2. 16. Nephritis, ii. 1. 2. 14. i. 1. 3. 9. iii. 2. 1. 14. Nerves decussate, iii. 2. 1. 10. Nictitation irritative, i. 1. 4. 1. ---- sensitive, ii. 1. 1. 8. ---- involuntary, iv. 1. 3. 2. Night-mare, iii. 2. 1. 13. Nipples, tension of, i. 1. 4. 7. iv. 1. 2. 6. Nostalgia, iii. 1. 2. 6. Nostrils, dry, i. 1. 3. 3. O. Obesitas, i. 2. 3. 17. Odontitis, ii. 1. 4. 7. Odontalgia, i. 2. 4. 12. Oesophagi schirrus, i. 2. 3. 25. Olfactus acrior, i. 1. 5. 3. ---- imminutus, i. 2. 5. 7. Oil destroys insects, i. 1. 4. 14. ---- essential of animals, i. 1. 2. 14. ---- why injurious in erysipelas, ii. 1. 3. 2. Opium in catarrh, i. 2. 3. 3. ---- in diaphragmitis, ii. 1. 2. 6. Ophthalmy, internal, ii. 1. 2. 2. ---- superficial, ii. 1. 4. 1. Orci timor, iii. 1. 2. 15. Oscitatio, ii. 1. 1. 9. Ossium innutritio, i. 2. 2. 14. Otitis, ii. 1. 4. 8. Otalgia, i. 2. 4. 13. iv. 2. 2. 8. Otopuosis, ii. 1. 4. 8. Ovary, dropsy of, i. 2. 3. 15. ---- exsection of, i. 2. 3. 15. Oxygenation of blood, iv. 1. 4. 6. Oxygen gas, Suppl. i. 9. 3. ---- in fevers, Suppl. i. 11. 7. i. 16. 9. P. Pain exhausts sensorial power, iv. 2. 2. ---- greater prevents less, iv. 2. 2. 2. ---- nervous, i. 2. 4. ---- of the little finger, symptom, iv. 2. 2. 12. ---- of arm in hydrothorax, iv. 2. 2. 13. ---- of the bile-duct, iv. 2. 2. 4. ---- of the shoulder, iv. 2. 2. 9. ---- of the pharynx, iv. 2. 2. 5. ---- of the testis, iv. 2. 2. 11. ---- smarting, i. 1. 5. 10. ---- of the side, i. 2. 4. 14. iv. 1. 2. 16. ---- of menstruation, i. 2. 1. 12. ---- use of, iii. 1. 1. 11. i. 1. 2. 9. ---- of the uterus, i. 2. 4. 17. Paint, white, dangerous, ii. 1. 4. 6. Palate, defect of, i. 2. 2. 20. Paleness, i. 2. 2. 2. ---- from fear, iv. 3. 1. 5. ---- from sickness, iv. 2. 1. 4. ---- of urine after dinner, iv. 2. 1. 2. ---- from cold skin, iv. 2. 1. 1. Palpitation of heart, i. 3. 3. 2. i. 2. 1. 10. ---- from fear, iv. 3. 1. 6. ---- relieved by arsenic, iv. 2. 1. 18. Pancreas, torpor of, i. 2. 2. 7. Pandiculatio, ii. 1. 1. 9. Panting, ii. 1. 1. 4. i. 3. 3. 3. Paracentesis at the navel, i. 2. 3. 13. Paralysis, iii. 2. 1. 10. ---- of the bladder, iii. 2. 1. 6. ---- of the rectum, iii. 2. 1. 7. ---- of the hands, iii. 2. 1. 4. ---- cure of, iii. 2. 1. 4. Paraplegia, iii. 2. 1. 11. Paresis inirritativa, i. 2. 1. 2. Suppl. i. 8. 10. ---- sensitiva, ii. 2. 1. 3. ---- voluntaria, iii. 2. 1. 8. Paronychia internal, ii. 1. 2. 19. ---- superficial, ii. 1. 4. 5. Parturition, ii. 1. 1. 12. ii. 1. 2. 16. ---- more fatal in high life, ii. 1. 1. 12. ---- with convulsion, iii. 1. 1. iii. 1. 1. 7. Parotitis, ii. 1. 3. 4. Passions depressing and exciting, iv. 3. 1. 5. Paupertatis timor, iii. 1. 2. 13. Pediculus, i. 1. 4. 15. Pemphigus, ii. 1. 3. 14. Penetration of animal bodies, iv. 1. 4. 7. Peripneumony, ii. 1. 2. 4. ---- tracheal, ii. 1. 2. 4. ---- superficial, ii. 1. 3. 7. ---- inirritated, ii. 1. 2. 4. Peritonitis, ii. 1. 2. 8. Perspiration not an excrement, i. 1. 2. 14. ---- greatest in the hot fit, i. 1. 2. 3. ---- fetid, i. 1. 2. 14. Pertussis, ii. 1. 3. 8. Pestis, ii. 1. 3. 13. Petechiæ, i. 2. 1. 17. ---- cure of, Suppl. i. 2. 7. Pharynx, pain of, iv. 2. 2. 5. Phthisis, pulmonary, ii. 1. 6. 7. Pimples on the face, ii. 1. 4. 6. Piles, bleeding, i. 2. 1. 6. ---- white, i. 1. 2. 12. Placenta, ii. 1. 1. 12. ii. 1. 2. 16. Plague, ii. 1. 3. 13. Plasters, why moist, i. 1. 3. 6. Pleurisy, ii. 1. 2. 5. Pleurodyne chronica, i. 2. 4. 14. ---- rheumatica, iv. 1. 2. 16. Podagra, iv. 1. 2. 15. iv. 2. 4. 9. Polypus of the lungs, i. 1. 3. 4. ---- of the nose from worms, iv. 1. 2. 9. Pregnancy, ii. 1. 1. 12. Priapismus, i. 1. 4. 6. ii. 1. 7. 9. Proctalgia, i. 2. 4. 18. Prolapsus ani, i. 1. 4. 9. Pruritus, i. 1. 5. 9. ---- narium a vermibus, iv. 2. 2. 6. Psora, ii. 1. 5. 6. ---- imaginaria, iii. 1. 2. 22. Ptyalismus. See Salivatio. Pubis and throat sympathize, iv. 1. 2. 7. Puerperal fever, i. 2. 4. 9. ii. 1. 6. 16. Add. 8. ---- insanity, iii. 1. 2. 1. Pulchritudinis desiderium, iii. 1. 2. 12. Pullulation of trees, iv. 1. 4. 3. Pulse full, why, i. 1. 1. 1. ---- strong, how determined, i. 1. 1. 1. Suppl. i. 16. 10. ---- soft in vomiting, iv. 2. 1. 17. ---- intermittent, iv. 2. 1. 18. ---- quick from paucity of blood, Suppl. i. 11. 4. ---- quick sometimes in sleep, iii. 2. 1. 12. ---- quick in weak people, iii. 2. 1. Sup. i. 11. 4. ---- slower by swinging, iv. 2. 1. 10. ---- quick in chlorosis, i. 2. 3. 10. Punctæ mucosæ vultûs, i. 2. 2. 9. Purging. See Diarrhoea. Pus diminished, i. 2. 2. 3. ---- distinguished from mucus, ii. 1. 6. 6. R. Rabies, iii. 1. 2. 18. Rachitis, i. 2. 2. 15. Raucedo catarrhal, ii. 1. 3. 5. ---- paralytic, iii. 2. 1. 5. Recollection, loss of, iii. 2. 2. 1. Recti paralysis, iii. 2. 1. 7. ---- schirrus, i. 2. 3. 23. Red-gum, ii. 1. 3. 12. i. 1. 2. 3. Redness from heat, ii. 1. 7. 7. ---- of joy, ii. 1. 7. 8. ---- after dinner, iv. 1. 1. 1. ---- of anger, iv. 2. 3. 5. ---- of guilt, iv. 2. 3. 6. ---- of modesty, iv. 2. 3. 6. Respiration, ii. 1. 1. 2. ---- quick in exercise, ii. 1. 1. 4. ---- in softness of bones, i. 2. 2. 14. Restlessness, iii. 1. 1. 1. Reverie, iii. 1. 2. 2. iv. 2. 4. 2. Rhaphania, iii. 1. 1. 6. Rheumatism, iv. 1. 2. 16. ---- of the joints, iv. 1. 2. 16. ---- of the bowels, iv. 1. 2. 16. ---- of the pleura, iv. 1. 2. 16. ---- suppurating, iv. 1. 2. 16. ---- from sympathy, iv. 2. 2. 13. ---- chronical, i. 1. 3. 12. iii. 1. 1. 6. Rickets, i. 2. 2. 15. Ring-worm, ii. 1. 5. 10. Risus, iii. 1. 1. 4. iv. 2. 3. 3. ---- sardonicus, iv. 1. 2. 4. ---- invitus, iv. 1. 3. 3. Rubeola, ii. 1. 3. 10. Rubor a calore, ii. 1. 7. 7. ---- jucunditatis, ii. 1. 7. 8. ---- pransorum, iv. 1. 1. 1. Ructus, i. 3. 1. 2. Ruminatio, i. 3. 1. 1. iv. 3. 3. 1. S. Sailing in phthisis, ii. 1. 6. 7. Salivation warm, i. 1. 2. 6. ---- lymphatic, i. 3. 2. 2. ---- sympathetic, iv. 1. 2. 5. ---- in low fevers, i. 1. 2. 6. Salt of urine, i. 1. 2. 4. i. 1. 3. 9. Satyriasis, iii. 1. 2. 16. Scabies. See Psora. Scarlatina, ii. 1. 3. 11. Scarlet fever, ii. 1. 3. 11. Scald-head, ii. 1. 5. 11. Sciatica frigida, i. 2. 4. 15. Schirrus, i. 2. 3. 22. ---- suppurans, ii. 1. 4. 15. ---- of the rectum, i. 2. 3. 23. ---- of the urethra, i. 2. 3. 24. ---- of the oesophagus, i. 2. 3. 25. Scorbutus, i. 2. 1. 15. ---- suppurans, ii. 1. 4. 14. Scrophula, i. 2. 3. 21. ---- suppurating, ii. 1. 4. 14. ---- produces insanity, iii. 1. 2. Scurvy, i. 2. 1. 15. ---- suppurating, ii. 1. 4. 14. Scurf of the head, i. 1. 3. 6. ---- of the tongue, i. 1. 3. 1. Sea air in phthisis, ii. 1. 6. 7. Seat, descent of, i. 1. 4. 9. Seed, ejection of, ii. 1. 1. 11. Sea-sickness, iv. 2. 1. 10. Suppl. i. 8. 3. See-saw of old people, iii. 2. 1. 2. Sensitive association, law of, iv. 2. 2. 2. Sensation inert, Suppl. i. 6. 4. Setons, ii. 1. 6. 6. Shingles, ii. 1. 5. 9. Shoulder, pain of, iv. 2. 2. 9. Shrieking, iii. 1. 1. 3. Sickness, i. 2. 4. 4. i. 3. 2. 3. ---- cured by a blister, iv. 1. 1. 3. ---- by warm skin, iv. 1. 1. 2. Suppl. i. 11. 4. ---- by whirling, i. 1. 1. 4. ---- by swinging, Suppl. i. 15. 3. ---- by hydrocarbonate gas, Suppl. i. 15. 3. ---- See Nausea. Sight acuter, i. 1. 5. 1. ---- impaired, i. 2. 5. 2. Side, chronical pain of, i. 2. 4. 14. Sighing and sobbing, iii. 1. 2. 10. Sitis calida, i. 2. 4. 1. ---- frigida, i. 2. 4. 1. ---- defectus, ii. 2. 2. 2. Skin pale in old age, i. 2. 2. 2. ---- from cold, i. 2. 2. 2. ---- dry, i. 1. 3. 6. ---- yellowish, i. 2. 2. 2. ---- bluish and shrunk, i. 2. 1. 1. ---- reddish, ii. 1. 3. 1. ---- cold after meals, iv. 2. 1. 1. Sleep, iii. 2. 1. 12. ---- interrupted, i. 2. 1. 3. ---- periods in, iv. 2. 4. 1. ---- with quick pulse, iii. 2. 1. 12. ---- disturbed by digestion, iii. 2. 1. 12. Sleep-walkers, iii. 1. 1. 9. Small-pox, ii. 1. 3. 9. ---- why distinct and confluent, Sup. i. 15. 2. ---- secondary fever of, ii. 1. 6. 12. ---- eruption of, iv. 1. 2. 12. Smarting, i. 1. 5. 10. Smell acuter, i. 1. 5. 3. ---- impaired, i. 2. 5. 7. Sneezing, ii. 1. 1. 3. iv. 1. 2. 2. Snow in scrophula, i. 2. 3. 21. ---- in paralysis, iii. 2. 1. 4. Snuff in hydrocephalus, i. 2. 3. 12. Somnambulism, iii. 1. 1. 9. Somnium, ii. 1. 7. 4. Somnus, iii. 2. 1. 12. iv. 2. 4. 1. ---- interruptus, i. 2. 1. 3. Softness of bones, i. 2. 2. 14. Spasm of diaphragm, iii. 1. 1. 11. ---- of the heart, iii. 1. 1. 11. Spine distorted, i. 2. 2. 16. ---- protuberant, i. 2. 2. 18. ---- bifid, i. 2. 2. 19. Spitting blood, i. 1. 1. 4. i. 2. 1. 9. Spleen swelled, i. 2. 3. 18. Suppl. i. 16. 6. Splenitis, ii. 1. 2. 13. Spots on the face, i. 2. 2. 9. Spots seen on bed-clothes, i. 2. 5. 3. Squinting, i. 2. 5. 4. ---- in hydrocephalus, i. 2. 5. 4. Stammering, iv. 2. 3. 1. Stays tight, injurious, ii. 1. 1. 12. Sterility, ii. 2. 2. 4. Sternutatio, ii. 1. 1. 3. iv. 1. 2. 2. ---- a lumine, iv. 1. 2. 2. Stimulants, their twofold effect, ii. 1. 2. 6. Stocks for children dangerous, i. 2. 2. 17. Stomach, torpor of, Suppl. i. 10. i. 16. 6. ---- inflammation of, ii. 1. 2. 10. ii. 1. 3. 19. ---- its association, iv. 1. 1. ---- cause of fever, Suppl. i. 8. 8. Stones in the bladder, See Calculi. ---- in horses, i. 1. 3. 5. i. 1. 3. 10. Strabismus, i. 2. 5. 4. Strangury, ii. 1. 1. 11. iv. 2. 2. 2. ---- convulsive, iv. 2. 2. 3. Strength and debility metaphors, i. 2. 1. Stridor dentium, iii. 1. 1. 12. Studium inane, iii. 1. 2. 2. iv. 2. 4. 2. Stultitia inirritabilis, i. 2. 5. 1. ---- insensibilis, ii. 2. 1. 1. ---- voluntaria, iii. 2. 2. 2. Stupor, i. 2. 5. 10. Suppl. i. 15. Subsultus tendinum, iii. 1. 1. 5. Sudor. See Sweats. Suggestion, slow, Surprise, i. 1. 5. 11. Sweats, warm, i. 1. 2. 3. ---- cold, i. 2. 3. 2. ---- lymphatic, i. 3. 2. 7. ---- asthmatic, i. 3. 2. 8. iv. 3. 1. 2. ---- covered in bed, iv. 1. 1. 2. Suppl. i. 11. 6 ---- in fever fits, why, i. 1. 2. 5. ---- from exercise, i. 1. 2. 3. ---- from heat, i. 1. 2. 3. ---- from medicines, i. 1. 2. 3. Sweaty hands cured, i. 3. 2. 7. Swinging, ii. 1. 6. 7. ---- makes the pulse slower, iv. 2. 1. 10. Swing centrifugal, Suppl. i. 15 and 3. Sympathy direct and reverse, iv. 1. 1. f. ---- with others, iii. 1. 2. 24. ---- of various parts, Suppl. i. 11. 5. ---- reverse of lacteals and lymphatics, Suppl. i. 11. 5 ---- of capillaries, Suppl. i. 11. 5. ---- direct of stomach and heart, Sup. i. 11. 5. ---- of throat and pubis, iv. 1. 2. 7. Syncope, i. 2. 1. 4. ---- epileptic, iii. 2. 1. 15. Syngultus, ii. 1. 1. 6. ---- nephriticus, iv. 1. 1. 7. Syphilis, ii. 1. 5. 2. ---- imaginaria, iii. 1. 2. 21. Syphon capillary of cloth, ii. 1. 3. 1. T. Tactus acrior, i. 1. 5. 5. ---- imminutus, i. 2. 5. 6. Tape-worm, i. 1. 4. 11. Tapping at the navel, i. 2. 3. 13. Taste. See Gustus. ---- bitter, not from bile, i. 1. 3. 1. Tædium vitæ, ii. 2. 1. 2. Tænia, i. 1. 4. 11. Tears sympathetic, iv. 1. 2. 1. iii. 1. 2. 10. Teeth, to preserve, i. 1. 4. 5. ---- fall out whole, ii. 1. 4. 7. Tenesmus, ii. 1. 1. 10. ---- calculosus, iv. 1. 2. 8. Testium dolor nephriticus, iv. 2. 2. 11. ---- tumor in gonorrhoea, iv. 1. 2. 18. ---- tumor in parotitide, iv. 1. 2. 19. Tetanus trismus, iii. 1. 1. 13. ---- doloroficus, iii. 1. 1. 14. Thirst. See Sitis and Adipsia. Thread-worm, i. 1. 4. 12. Throat swelled, i. 2. 3. 20. ---- thickens at puberty, iv. 2. 1. 7. ---- grown up, i. 2. 3. 25. Thrush, ii. 1. 3. 17. Tickling, i. 1. 5. 8. Timor orci, iii. 1. 2. 15. ---- lethi, iii. 1. 2. 14. ---- paupertatis, iii. 1. 2. 13. Tinea, ii. 1. 5. 11. Tinnitus aurium, iv. 2. 1. 15. Titillatio, i. 1. 5. 8. Titubatio linguæ, iv. 2. 3. 1. Tobacco, smoke of in piles, i. 2. 1. 6. Tongue dry, i. 1. 3. 1. Suppl. i. 2. ---- coloured mucus, i. 1. 3. 1. Tonsillitis, ii. 1. 3. 3. Tonsils swelled from bad teeth, i. 2. 3. 21. ii. 1. 3. 3. Torpor of the liver, i. 2. 2. 6. ---- of the pancreas, i. 2. 2. 7. ---- of the lungs, Suppl. 1. 9. ---- of the stomach, Suppl. i. 10. ---- of the heart, Suppl. i. 10. Tooth-ach, i. 2. 4. 12. ii. 1. 4. 7. Tooth-edge, iv. 1. 2. 3. Toothing, i. 1. 4. 5. Tooth-powder, i. 1. 4. 5. Touch. See Tactus. ---- deceived three ways, i. 2. 5. 9. iv. 2. 1. 10. Transfusion of blood, i. 2. 3. 25. Suppl. i. 14. 4. Translation of matter, i. 3. 2. 9. ---- of milk, i. 3. 2. 10. ---- of urine, i. 3. 2. 11. Transparency of cornea, i. 1. 4. 1. ---- of crystalline, i. 2. 2. 13. ---- of air before rain, i. 1. 4. 1. Tremor of old age, iii. 2. 1. 3. ---- of fever, iii. 1. 1. 2. ---- of anger, iv. 2. 3. 4. ---- of fear, iv. 3. 1. 5. Tussis ebriorum, ii. 1. 1. 5. ---- convulsiva, ii. 1. 3. 8. ---- hepatica, iv. 2. 1. 8. ---- arthritica, iv. 2. 1. 9. ---- periodica, iv. 3. 4. 2. ---- a pedibus frigidis, iv. 2. 1. 7. Tympany, i. 2. 4. 9. U. Ulcers, healing of, i. 1. 3. 13. ---- of the cornea, i. 1. 3. 14. ---- from burns, i. 1. 3. 13. ---- scrophulous, ii. 1. 4. 13. ---- of the throat, ii. 1. 3. 3. ii. 1. 3. 11. ---- of the legs, ii. 1. 4. 14. Unguium morsiuncula, iv. 1. 3. 5. Urethra, scirrhus of, i. 2. 3. 24. ---- fistula of, ii. 1. 4. 11. Urine copious, coloured, i. 1. 2. 4. ---- copious, pale, i. 2. 3. 5. ---- diminished, coloured, i. 1. 3. 7. ---- diminished, pale, i. 2. 2. 5. ---- its mucus, salts, Prussian blue, i. 1. 2. 4. ---- why less and coloured in dropsies, i. 1. 3. 7. ---- translation of, i. 3. 2. 11. ---- difficulty of, iii. 2. 1. 6. ---- not secreted, i. 2. 2. 8. ---- pale after meals, iv. 2. 1. 2. ---- pale from cold skin, iv. 2. 1. 3. ---- sediment in fevers, Suppl. i. 2. 3. ---- pale in fevers, Suppl. i. 2. 3. and 5. Urticaria, ii. 1. 3. 16. Uteri descensus, i. 1. 4. 8. V. Vacillatio senilis, iii. 2. 1. 2. Varicella, ii. 1. 3. 15. Variola, ii. 1. 3. 9. ---- eruption of, iv. 1. 2. 12. Vasorum capil retrogressio, i. 3. 3. 1. Venereal orgasm, iv. 1. 4. 4. ---- disease, ii. 1. 5. 2. ---- imaginary, iii. 1. 2. 21. Ventriculi ægritudo, i. 2. 4. 4. ---- vesicatorio sanata, iv. 1. 1. 3. Vermes, i. 1. 4. 10. Vertigo rotatory, iv. 2. 1. 10. ---- of sight, iv. 2. 1. 11. ---- inebriate, iv. 2. 1. 12. ---- of fever, iv. 2. 1. 13. ---- from the brain, iv. 2. 1. 14. ---- of the ears, iv. 2. 1. 15. ---- of the touch, Addit. iii. ---- of the touch, taste and smell, iv. 2. 1. 16. ---- with vomiting, iv. 3. 2. 3. ---- produces slow pulse, iv. 2. 1. 10. ---- of blind men, iv. 2. 1. 10. ---- use of mercurials in it, iv. 2. 1. 11. ---- from ideas, Addit. iii. Vibices, i. 2. 1. 16. Suppl. i. 2. 7. Vigilia, iii. 1. 2. 3. iv. 1. 3. 6. Vision acuter, i. 1. 5. 1. ---- diminished, i. 2. 5. 2. ---- expends much sensorial power, i. 2. 5. 3. Vita ovi, iv. 1. 4. 1. ---- hiemi-dormientium, iv. 1. 4. 2. Vitus's dance, iv. 2. 3. 2. Volition, three degrees of, iii. 2. 1. 12. ---- lessens fever, iii. 2. 1. 12. Suppl. i. 11. 6. ---- produces fever, iii. 2. 1. 12. ---- without deliberation, iv. 1. 3. 2. Addit. iv. Vomica, ii. 1. 6. 3. Vomitus, i. 3. 1. 4. Vomendi conamen inane, i. 3. 1. 8. Vomiting stopped, iv. 1. 1. 3. iv. 1. 1. f. ---- voluntary, iv. 3. 3. 2. ---- how acquired, iv. 1. 1. 2. ---- vertiginous, iv. 3. 2. 3. ---- from stone in ureter, iv. 3. 2. 4. ---- from paralytic stroke, iv. 3. 2. 5. ---- from tickling the throat, iv. 3. 2. 6. ---- sympathizes with the skin, iv. 3. 2. 7. ---- in hæmoptoe, i. 1. 1. 4. ---- from defect of association, iv. 2. 1. 10. Vulnerum cicatrix, i. 1. 3. 13. W. Watchfulness, iii. 1. 2. 3. iv. 1. 3. 6. Water-qualm, i. 3. 1. 3. Weakness, three kinds of, i. 2. 1. Whirling-chair, Suppl. i. 15. 3. Whirling-bed, Suppl. i. 15. 7. White swelling of the knee, i. 2. 3. 19. Winking, ii. 1. 1. 8. i. 1. 4. 1. iv. 1. 3. 2. Wine in fevers, ii. 1. 3. 1. iv. 2. 1. 12. Winter-sleeping animals, iv. 1. 4. 2. Witlow, superficial, ii. 1. 4. 5. ---- internal, ii. 1. 2. 19. Womb, descent of, i. 1. 4. 8. ---- inflammation of, ii. 1. 2. 16. Worms, i. 1. 4. 10. ---- mucus counterfeits, i. 1. 3. 4. ---- in sheep, i. 2. 3. 9. Wounds, healing of, i. 1. 3. 13. Y. Yawning, ii. 1. 1. 9. Yaws, ii. 1. 5. 5. Z. Zona ignea, ii. 1. 5. 9. iv. 1. 2. 11. ii. 1. 2. 14. * * * * * ZOONOMIA; OR, THE LAWS OF ORGANIC LIFE. PART III. CONTAINING THE ARTICLES OF THE MATERIA MEDICA, WITH AN ACCOUNT OF THE OPERATION OF MEDICINES. * * * * * IN VIVUM CORPUS AGUNT MEDICAMENTA. * * * * * PREFACE. THE MATERIA MEDICA includes all those substances, which may contribute to the restoration of health. These may be conveniently distributed under seven articles according to the diversity of their operations. 1. NUTRIENTIA, or those things which preserve in their natural state the due exertions of all the irritative motions. 2. INCITANTIA, or those things which increase the exertions of all the irritative motions. 3. SECERNENTIA, or those things which increase the irritative motions, which constitute secretion. 4. SORBENTIA, or those things which increase the irritative motions, which constitute absorption. 5. INVERTENTIA, or those things which invert the natural order of the successive irritative motions. 6. REVERTENTIA, or those things which restore the natural order of the inverted irritative motions. 7. TORPENTIA, those things which diminish the exertions of all the irritative motions. It is necessary to apprize the reader, that in the following account of the virtues of Medicines their usual doses are always supposed to be exhibited; and the patient to be exposed to the degree of exterior heat, which he has been accustomed to, (where the contrary is not mentioned), as any variation of either of these circumstances varies their effects. * * * * * ARTICLES OF THE MATERIA MEDICA. * * * * * ART. I. NUTRIENTIA. I. 1. Those things, which preserve in their natural state the due exertions of all the irritative motions, are termed nutrientia; they produce the growth, and restore the waste, of the system. These consist of a variety of mild vegetable and animal substances, water, and air. 2. Where stronger stimuli have been long used, they become necessary for this purpose, as mustard, spice, salt, beer, wine, vinegar, alcohol, opium. Which however, as they are unnatural stimuli, and difficult to manage in respect to quantity, are liable to shorten the span of human life, sooner rendering the system incapable of being stimulated into action by the nutrientia. See Sect XXXVII. 4. On the same account life is shorter in warmer climates than in more temperate ones. II. OBSERVATIONS ON THE NUTRIENTIA. I. 1. The flesh of animals contains more nourishment, and stimulates our absorbent and secerning vessels more powerfully, than the vegetable productions, which we use as food; for the carnivorous animals can fast longer without injury than the graminivorous; and we feel ourselves warmer and stronger after a meal of flesh than of grain. Hence in diseases attended with cold extremities and general debility this kind of diet is preferred; as in rickets, dropsy, scrophula, and in hysteric and hypochondriac cases, and to prevent the returns of agues. Might not flesh in small quantities bruised to a pulp be more advantageously used in fevers attended with debility than vegetable diet? That flesh, which is of the darkest colour, generally contains more nourishment, and stimulates our vessels more powerfully, than the white kinds. The flesh of the carnivorous and piscivorous animals is so stimulating, that it seldom enters into the food of European nations, except the swine, the Soland goose (Pelicanus Bassanus), and formerly the swan. Of these the swine and the swan are fed previously upon vegetable aliment; and the Soland goose is taken in very small quantity, only as a whet to the appetite. Next to these are the birds, that feed upon insects, which are perhaps the most stimulating and the most nutritive of our usual food. It is said that a greater quantity of volatile alkali can be obtained from this kind of flesh, to which has been ascribed its stimulating quality. But it is more probable, that fresh flesh contains only the elements of volatile alkali. 2. Next to the dark coloured flesh of animals, the various tribes of shell-fish seem to claim their place, and the wholesome kinds of mushrooms, which must be esteemed animal food, both for their alkalescent tendency, their stimulating quality, and the quantity of nourishment, which they afford; as oysters, lobsters, crabfish, shrimps; mushrooms; to which perhaps might be added some of the fish without scales; as the eel, barbolt, tench, smelt, turbot, turtle. The flesh of many kinds of fish, when it is supposed to have undergone a beginning putrefaction, becomes luminous in the dark. This seems to shew a tendency in the phosphorus to escape, and combine with the oxygen of the atmosphere; and would hence shew, that this kind of flesh is not so perfectly animalized as those before mentioned. This light, as it is frequently seen on rotten wood, and sometimes on veal, which has been kept too long, as I have been told, is commonly supposed to have its cause from putrefaction; but is nevertheless most probably of phosphoric origin, like that seen in the dark on oyster-shells, which have previously been ignited, and afterwards exposed to the sunshine, and on the Bolognian stone. See Botan. Gard. Vol. I. Cant. I. line 1 and 2, the note. 3. The flesh of young animals, as of lamb, veal, and sucking pigs, supplies us with a still less stimulating food. The broth of these is said to become sour, and continues so a considerable time before it changes into putridity; so much does their flesh partake of the chemical properties of the milk, with which these animals are nourished. 4. The white meats, as of turkey, partridge, pheasant, fowl, with their eggs, seem to be the next in mildness; and hence are generally first allowed to convalescents from inflammatory diseases. 5. Next to those should be ranked the white river-fish, which have scales, as pike, perch, gudgeon. II. 1. Milk unites the animal with the vegetable source of our nourishment, partaking of the properties of both. As it contains sugar, and will therefore ferment and produce a kind of wine or spirit, which is a common liquor in Siberia; or will run into an acid by simple agitation, as in the churning of cream; and lastly, as it contains coagulable lymph, which will undergo the process of putrefaction like other animal substances, as in old cheese. 2. Milk may be separated by rest or by agitation into cream, butter, butter-milk, whey, curd. The cream is easier of digestion to adults, because it contains less of the coagulum or cheesy part, and is also more nutritive. Butter consisting of oil between an animal and vegetable kind contains still more nutriment, and in its recent state is not difficult of digestion if taken in moderate quantity. See Art. I. 2. 3. 2. Butter-milk if it be not bitter is an agreeable and nutritive fluid, if it be bitter it has some putrid parts of the cream in it, which had been kept too long; but is perhaps not less wholesome for being sour to a certain degree: as the inferior people in Scotland choose sour milk in preference to skimmed milk before it is become sour. Whey is the least nutritive and easiest of digestion. And in the spring of the year, when the cows feed on young grass, it contains so much of vegetable properties, as to become a salutary potation, when drank to about a pint every morning to those, who during the winter have taken too little vegetable nourishment, and who are thence liable to bilious concretions. 3. Cheese is of various kinds, according to the greater or less quantity of cream, which it contains, and according to its age. Those cheeses, which are easiest broken to pieces in the mouth, are generally easiest of digestion, and contain most nutriment. Some kinds of cheese, though slow of digestion, are also slow in changing by chemical processes in the stomach, and therefore will frequently agree well with those, who have a weak digestion; as I have seen toasted cheese vomited up a whole day after it was eaten without having undergone any apparent change, or given any uneasiness to the patient. It is probable a portion of sugar, or of animal fat, or of the gravy of boiled or roasted meat, mixed with cheese at the time of making it, might add to its pleasant and nutritious quality. 4. The reason, why autumnal milk is so much thicker or coagulable than vernal milk, is not easy to understand, but as new milk is in many respects similar to chyle, it may be considered as food already in part digested by the animal it is taken from, and thence supplies a nutriment of easy digestion. But as it requires to be curdled by the gastric acid, before it can enter the lacteals, as is seen in the stomachs of calves, it seems more suitable to children, whose stomachs abound more with acidity, than to adults; but nevertheless supplies good nourishment to many of the latter, and particularly to those, who use vegetable food, and whose stomachs have not been much accustomed to the unnatural stimulus of spice, salt, and spirit. See Class I. 1. 2. 5. III. 1. The seeds, roots, leaves, and fruits of plants, constitute the greatest part of the food of mankind; the respective quantities of nourishment, which these contain, may perhaps be estimated from the quantity of starch, or of sugar, they can be made to produce: in farinaceous seeds, the mucilage seems gradually to be converted into starch, while they remain in our granaries; and the starch by the germination of the young plant, as in making malt from barley, or by animal digestion, is converted into sugar. Hence old wheat and beans contain more starch than new; and in our stomachs other vegetable and animal materials are converted into sugar; which constitutes in all creatures a part of their chyle. Hence it is probable, that sugar is the most nutritive part of vegetables; and that they are more nutritive, as they are convertible in greater quantity into sugar by the power of digestion; as appears from sugar being found in the chyle of all animals, and from its existing in great quantity in the urine of patients in the diabætes, of which a curious case is related in Sect. XXIX. 4. where a man labouring under this malady eat and drank an enormous quantity, and sometimes voided sixteen pints of water in a day, with an ounce of sugar in each pint. 2. Oil, when mixed with mucilage or coagulable lymph, as in cream or new milk, is easy of digestion, and constitutes probably the most nutritive part of animal diet; as oil is another part of the chyle of all animals. As these two materials, sugar and butter, contain much nutriment under a small volume, and readily undergo some chemical change so as to become acid or rancid; they are liable to disturb weak stomachs, when taken in large quantity, more than aliment, which contains less nourishment, and is at the same time less liable to chemical changes; because the chyle is produced quicker than the torpid lacteals can absorb it, and thence undergoes a further chemical process. Sugar and butter therefore are not so easily digested, when taken in large quantity, as those things, which contain less nutriment; hence, where the stomach is weak, they must be used in less quantity. But the custom of some people in restraining children entirely from them, is depriving them of a very wholesome, agreeable, and substantial part of their diet. Honey, manna, sap-juice, are different kinds of less pure sugar. 3. All the esculent vegetables contain a bland oil, or mucilage, or starch, or sugar, or acid; and, as their stimulus is moderate, are properly given alone as food in inflammatory diseases; and mixed with milk constitute the food of thousands. Other vegetables possess various degrees and various kinds of stimulus; and to these we are beholden for the greater part of our Materia Medica, which produce nausea, sickness, vomiting, catharsis, intoxication, inflammation, and even death, if unskilfully administered. The acrid or intoxicating, and other kinds of vegetable juices, such as produce sickness, or evacuate the bowels, or such even as are only disagreeable to the palate, appear to be a part of the defence of those vegetables, which possess them, from the assaults of larger animals or of insects. As mentioned in the Botanic Garden, Part II. Cant. I. line 161, note. This appears in a forcible manner from the perusal of some travels, which have been published of those unfortunate people, who have suffered shipwreck on uncultivated countries, and have with difficulty found food to subsist, in otherwise not inhospitable climates. 4. As these acrid and intoxicating juices generally reside in the mucilage, and not in the starch of many roots, and seeds, according to the observation of M. Parmentier, the wholesome or nutritive parts of some vegetables may be thus separated from the medicinal parts of them. Thus if the root of white briony be rasped into cold water, by means of a bread-grater made of a tinned iron plate, and agitated in it, the acrid juice of the root along with the mucilage will be dissolved, or swim, in the water; while a starch perfectly wholesome and nutritious will subside, and may be used as food in times of scarcity. M. Parmentier further observes, that potatoes contain too much mucilage in proportion to their starch, which prevents them from being converted into good bread. But that if the starch be collected from ten pounds of raw potatoes by grating them into cold water, and agitating them, as above mentioned; and if the starch thus procured be mixed with other ten pounds of boiled potatoes, and properly subjected to fermentation like wheat flour, that it will make as good bread as the finest wheat. Good bread may also be made by mixing wheat-flour with boiled potatoes. Eighteen pounds of wheat flour are said to make twenty-two pounds and a half of bread. Eighteen pounds of wheat-flour mixed with nine pounds of boiled potatoes, are said to make twenty-nine pounds and a half of bread. This difference of weight must arise from the difference of the previous dryness of the two materials. The potatoes might probably make better flour, if they were boiled in steam, in a close vessel, made some degrees hotter than common boiling water. Other vegetable matters may be deprived of their too great acrimony by boiling in water, as the great variety of the cabbage, the young tops of white briony, water-cresses, asparagus, with innumerable roots, and some fruits. Other plants have their acrid juices or bitter particles diminished by covering them from the light by what is termed blanching them, as the stems and leaves of cellery, endive, sea-kale. The former method either extracts or decomposes the acrid particles, and the latter prevents them from being formed. See Botanic Garden, Vol. I. additional note XXXIV. on the Etiolation of vegetables. 5. The art of cookery, by exposing vegetable and animal substances to heat, has contributed to increase the quantity of the food of mankind by other means besides that of destroying their acrimony. One of these is by converting the acerb juices of some fruits into sugar, as in the baking of unripe pears, and the bruising of unripe apples; in both which situations the life of the vegetable is destroyed, and the conversion of the harsh juice into a sweet one must be performed by a chemical process; and not by a vegetable one only, as the germination of barley in making malt has generally been supposed. Some circumstances, which seem to injure the life of several fruits, seem to forward the saccharine process of their juices. Thus if some kinds of pears are gathered a week before they would ripen on the tree, and are laid on a heap and covered, their juice becomes sweet many days sooner. The taking off a circular piece of the bark from a branch of a pear-tree causes the fruit of that branch to ripen sooner by a fortnight, as I have more than once observed. The wounds made in apples by insects occasion those apples to ripen sooner; caprification, or the piercing of figs, in the island of Malta, is said to ripen them sooner; and I am well informed, that when bunches of grapes in this country have acquired their expected size, that if the stalk of each bunch be cut half through, that they will sooner ripen. The germinating barley in the malt-house I believe acquires little sweetness, till the life of the seed is destroyed, and the saccharine process then continued or advanced by the heat in drying it. Thus in animal digestion, the sugar produced in the stomach is absorbed by the lacteals as fast as it is made, otherwise it ferments, and produces flatulency; so in the germination of barley in the malt-house, so long as the new plant lives, the sugar, I suppose, is absorbed as fast as it is made; but that, which we use in making beer, is the sugar produced by a chemical process after the death of the young plant, or which is made more expeditiously, than the plant can absorb it. It is probably this saccharine process, which obtains in new hay-stacks too hastily, and which by immediately running into fermentation produces so much heat as to set them on fire. The greatest part of the grain, or seeds, or roots, used in the distilleries, as wheat, canary seed, potatoes, are not I believe previously subjected to germination, but are in part by a chemical process converted into sugar, and immediately subjected to vinous fermentation; and it is probable a process may sometime be discovered of producing sugar from starch or meal; and of separating it from them for domestic purposes by alcohol, which dissolves sugar but not mucilage; or by other means. Another method of increasing the nutriment of mankind by cookery, is by dissolving cartilages and bones, and tendons, and probably some vegetables, in steam or water at a much higher degree of heat than that of boiling. This is to be done in a close vessel, which is called Papin's digester; in which, it is said, that water may be made red-hot, and will then dissolve all animal substances; and might thus add to our quantity of food in times of scarcity. This vessel should be made of iron, and should have an oval opening at top, with an oval lid of iron larger than the aperture; this lid should be slipped in endways, when the vessel is filled, and then turned, and raised by a screw above it into contact with the under edges of the aperture. There should also be a small tube or hole covered with a weighted valve to prevent the danger of bursting the digester. Where the powers of digestion are weakened, broths made by boiling animal and vegetable substances in water afford a nutriment; though I suppose not so great as the flesh and vegetables would afford, if taken in their solid form, and mixed with saliva in the act of mastication. The aliment thus prepared should be boiled but a short time, nor should be suffered to continue in our common kitchen-utensils afterwards, as they are lined with a mixture of half lead and half tin, and are therefore unwholesome, though the copper is completely covered. And those soups, which have any acid or wine boiled in them, unless they be made in silver, or in china, or in those pot-vessels, which are not glazed by the addition of lead, are truly poisonous; as the acid, as lemon-juice or vinegar, when made hot, erodes or dissolves the lead and tin lining of the copper-vessels, and the leaden glaze of the porcelain ones. Hence, where silver cannot be had, iron vessels are preferable to tinned copper ones; or those made of tinned iron-plates in the common tin-shops, which are said to be covered with pure or block tin. 6. Another circumstance, which facilitates the nourishment of mankind, is the mechanic art of grinding farinaceous seeds into powder between mill-stones; which may be called the artificial teeth of society. It is probable, that some soft kinds of wood, especially when they have undergone a kind of fermentation, and become of looser texture, might be thus used as food in times of famine. Nor is it improbable, that hay, which has been kept in stacks, so as to undergo the saccharine process, may be so managed by grinding and by fermentation with yeast like bread, as to serve in part for the sustenance of mankind in times of great scarcity. Dr. Priestley gave to a cow for some time a strong infusion of hay in large quantity for her drink, and found that she produced during this treatment above double the quantity of milk. Hence if bread cannot be made from ground hay, there is great reason to suspect, that a nutritive beverage may be thus prepared either in its saccharine state, or fermented into a kind of beer. In times of great scarcity there are other vegetables, which though not in common use, would most probably afford wholesome nourishment, either by boiling them, or drying and grinding them, or by both those processes in succession. Of these are perhaps the tops and the bark of all those vegetables, which are armed with thorns or prickles, as gooseberry trees, holly, gorse, and perhaps hawthorn. The inner bark of the elm tree makes a kind of gruel. And the roots of fern, and probably of very many other roots, as of grass and of clover taken up in winter, might yield nourishment either by boiling or baking, and separating the fibres from the pulp by beating them; or by getting only the starch from those, which possess an acrid mucilage, as the white briony. 7. However the arts of cookery and of grinding may increase or facilitate the nourishment of mankind, the great source of it is from agriculture. In the savage state, where men live solely by hunting, I was informed by Dr. Franklin, that there was seldom more than one family existed in a circle of five miles diameter; which in a state of pasturage would support some hundred people, and in a state of agriculture many thousands. The art of feeding mankind on so small a grain as wheat, which seems to have been discovered in Egypt by the immortal name of Ceres, shewed greater ingenuity than feeding them with the large roots of potatoes, which seem to have been a discovery of ill-fated Mexico. This greater production of food by agriculture than by pasturage, shews that a nation nourished by animal food will be less numerous than if nourished by vegetable; and the former will therefore be liable, if they are engaged in war, to be conquered by the latter, as Abel was slain by Cain. This is perhaps the only valid argument against inclosing open arable fields. The great production of human nourishment by agriculture and pasturage evinces the advantage of society over the savage state; as the number of mankind becomes increased a thousand fold by the arts of agriculture and pasturage; and their happiness is probably under good governments improved in as great a proportion, as they become liberated from the hourly fear of beasts of prey, from the daily fear of famine, and of the occasional incursions of their cannibal neighbours. But pasturage cannot exist without property both in the soil, and the herds which it nurtures; and for the invention of arts, and production of tools necessary to agriculture, some must think, and others labour; and as the efforts of some will be crowned with greater success than that of others, an inequality of the ranks of society must succeed; but this inequality of mankind in the present state of the world is too great for the purposes of producing the greatest quantity of human nourishment, and the greatest sum of human happiness; there should be no slavery at one end of the chain of society, and no despotism at the other.--By the future improvements of human reason such governments may possibly hereafter be established, as may a hundred-fold increase the numbers of mankind, and a thousand-fold their happiness. IV. 1. Water must be considered as a part of our nutriment, because so much of it enters the composition of our solids as well as of our fluids; and because vegetables are now believed to draw almost the whole of their nourishment from this source. As in them the water is decomposed, as it is perspired by them in the sunshine, the oxygen gas increases the quantity and the purity of the atmosphere in their vicinity, and the hydrogen seems to be retained, and to form the nutritive juices, and consequent secretions of rosin, gum, wax, honey, oil, and other vegetable productions. See Botanic Garden, Part I. Cant. IV. line 25, note. It has however other uses in the system, besides that of a nourishing material, as it dilutes our fluids, and lubricates our solids; and on all these accounts a daily supply of it is required. 2. River-water is in general purer than spring-water; as the neutral salts washed down from the earth decompose each other, except perhaps the marine salt; and the earths, with which spring-water frequently abounds, is precipitated; yet it is not improbable, that the calcareous earth dissolved in the water of many springs may contribute to our nourishment, as the water from springs, which contain earth, is said to conduce to enrich those lands, which are flooded with it, more than river water. 3. Many arguments seem to shew, that calcareous earth contributes to the nourishment of animals and vegetables. First because calcareous earth constitutes a considerable part of them, and must therefore either be received from without, or formed by them, or both, as milk, when taken as food by a lactescent woman, is decomposed in the stomach by the process of digestion, and again in part converted into milk by the pectoral glands. Secondly, because from the analogy of all organic life, whatever has composed a part of a vegetable or animal may again after its chemical solution become a part of another vegetable or animal, such is the general transmigration of matter. And thirdly, because the great use of lime in agriculture on almost all kinds of soil and situation cannot be satisfactorily explained from its chemical properties alone. Though these may also in certain soils and situations have considerable effect. The chemical uses of lime in agriculture may be, 1. from its destroying in a short time the cohesion of dead vegetable fibres, and thus reducing them to earth, which otherwise is effected by a slow process either by the consumption of insects or by a gradual putrefaction. Thus I am informed that a mixture of lime with oak bark, after the tanner has extracted from it whatever is soluble in water, will in two or three months reduce it to a fine black earth, which, if only laid in heaps, would require as many years to effect by its own spontaneous fermentation or putrefaction. This effect of lime must be particularly advantageous to newly inclosed commons when first broken up. Secondly, lime for many months continues to attract moisture from the air or earth, which it deprives I suppose of carbonic acid, and then suffers it to exhale again, as is seen on the plastered walls of new houses. On this account it must be advantageous when mixed with dry or sandy soils, as it attracts moisture from the air above or the earth beneath, and this moisture is then absorbed by the lymphatics of the roots of vegetables. Thirdly, by mixing lime with clays it is believed to make them less cohesive, and thus to admit of their being more easily penetrated by vegetable fibres. A mixture of lime with clays destroys their superabundancy of acid, if such exists, and by uniting with it converts it into gypsum or alabaster. And lastly, fresh lime destroys worms, snails, and other insects, with which it happens to come in contact. Yet do not all these chemical properties seem to account for the great uses of lime in almost all soils and situations, as it contributes so much to the melioration of the crops, as well as to their increase in quantity. Wheat from land well limed is believed by farmers, millers, and bakers, to be, as they suppose, thinner skinned; that is, it turns out more and better flour; which I suppose is owing to its containing more starch and less mucilage. In respect to grass-ground I am informed, that if a spadeful of lime be thrown on a tussock, which horses or cattle have refused to touch for years, they will for many succeeding seasons eat it quite close to the ground. One property of lime is not perhaps yet well understood, I mean its producing so much heat, when it is mixed with water; which may be owing to the elementary fluid of heat consolidated in the lime. It is the steam occasioned by this heat, when water is sprinkled upon lime, if the water be not in too great quantity or too cold, which breaks the lime into such fine powder as almost to become fluid, which cannot be effected perhaps by any other means, and which I suppose must give great preference to lime in agriculture, and to the solutions of calcareous earth in water, over chalk or powdered limestone, when spread upon the land. 4. It was formerly believed that waters replete with calcareous earth, such as incrust the inside of tea-kettles, or are laid to petrify moss, were liable to produce or to increase the stone in the bladder. This mistaken idea has lately been exploded by the improved chemistry, as no calcareous earth, or a very minute quantity, was found in the calculi analysed by Scheel and Bergman. The waters of Matlock and of Carlsbad, both which cover the moss, which they pass through, with a calcareous crust, are so far from increasing the stone of the bladder or kidnies, that those of Carlsbad are celebrated for giving relief to those labouring under these diseases. Philos. Trans. Those of Matlock are drank in great quantities without any suspicion of injury; and I well know a person who for above ten years has drank about two pints a day of cold water from a spring, which very much incrusts the vessels, it is boiled in, with calcareous earth, and affords a copious calcareous sediment with a solution of salt of tartar, and who enjoys a state of uninterrupted health. V. 1. As animal bodies consist much both of oxygen and azote, which make up the composition of atmospheric air, these should be counted amongst nutritious substances. Besides that by the experiments of Dr. Priestley it appears, that the oxygen gains admittance into the blood through the moist membranes of the lungs; and seems to be of much more immediate consequence to the preservation of our lives than the other kinds of nutriment above specified. As the basis of fixed air, or carbonic acid gas, is carbone, which also constitutes a great part both of vegetable and animal bodies; this air should likewise be reckoned amongst nutritive substances. Add to this, that when this carbonic acid air is swallowed, as it escapes from beer or cyder, or when water is charged with it as detruded from limestone by vitriolic acid, it affords an agreeable sensation both to the palate and stomach, and is therefore probably nutritive. The immense quantity of carbone and of oxygen which constitute so great a part of the limestone countries is almost beyond conception, and, as it has been formed by animals, may again become a part of them, as well as the calcareous matter with which they are united. Whence it may be conceived, that the waters, which abound with limestone in solution, may supply nutriment both to animals and to vegetables, as mentioned above. VI. 1. The manner, in which nutritious particles are substituted in the place of those, which are mechanically abraded, or chemically decomposed, or which vanish by animal absorption, must be owing to animal appetency, as described in Sect. XXXVII. 3. and is probably similar to the process of inflammation, which produces new vessels and new fluids; or to that which constitutes the growth of the body to maturity. Thus the granulations of new flesh to repair the injuries of wounds are visible to the eye; as well as the callous matter, which cements broken bones; the calcareous matter, which repairs injured snail-shells; and the threads, which are formed by silk-worms and spiders; which are all secreted in a softer state, and harden by exsiccation, or by the contact of the air, or by absorption of their more fluid parts. Whether the materials, which thus supply the waste of the system, can be given any other way than by the stomach, so as to preserve the body for a length of time, is worth our inquiry; as cases sometimes occur, in which food cannot be introduced into the stomach, as in obstructions of the oesophagus, inflammations of the throat, or in hydrophobia; and other cases are not unfrequent in which the power of digestion is nearly or totally destroyed, as in anorexia epileptica, and in many fevers. In the former of these circumstances liquid nutriment may sometimes be got into the stomach through a flexible catheter; as described in Class III. 1. 1. 15. In the latter many kinds of mild aliment, as milk or broth, have frequently been injected as clysters, together with a small quantity of opium, as ten drops of the tincture, three or four times a day; to which also might be added very small quantities of vinous spirit. But these, as far as I have observed, will not long sustain a person, who cannot take any sustenance by the stomach. 2. Another mode of applying nutritive fluids might be by extensive fomentations, or by immerging the whole body in a bath of broth, or of warm milk, which might at the same time be coagulated by rennet, or the acid of the calf's stomach; broth or whey might thus probably be introduced, in part at least, into the circulation, as a solution of nitre is said to have been absorbed in a pediluvium, which was afterwards discovered by the manner in which paper dipped frequently in the urine of the patient and dried, burnt and sparkled like touch-paper. Great quantity of water is also known to be absorbed by those, who have bathed in the warm bath after exercise and abstinence from liquids. Cleopatra was said to travel with 4000 milch-asses in her train, and to bathe every morning in their milk, which she probably might use as a cosmetic rather than a nutritive. 3. The transfusion of blood from another animal into the vein of one, who could take no sustenance by the throat, or digest none by the stomach, might long continue to support him; and perhaps other nutriment, as milk or mucilage, might be this way introduced into the system, but we have not yet sufficient experiments on this subject. See Sect. XXXII. 4. and Class I. 2. 3. 25. and Sup. I. 14. 2. VII. Various kinds of condiments, or sauces, have been taken along with vegetable or animal food, and have been thought by some to strengthen the process of digestion and consequent process of nutrition. Of these wine, or other fermented liquors, vinegar, salt, spices, and mustard, have been in most common use, and I believe to the injury of thousands. As the stomach by their violent stimulus at length loses its natural degree of irritability, and indigestion is the consequence; which is attended with flatulency and emaciation. Where any of these have been taken so long as to induce a habit, they must either be continued, but not increased; or the use of them should be gradually and cautiously diminished or discontinued, as directed in Sect. XII. 7. 8. III. CATALOGUE OF THE NUTRIENTIA. I. 1. Venison, beef, mutton, hare, goose, duck, woodcock, snipe, moor-game. 2. Oysters, lobsters, crabs, shrimps, mushrooms, eel, tench, barbolt, smelt, turbot, sole, turtle. 3. Lamb, veal, sucking-pig. 4. Turkey, partridge, pheasant, fowl, eggs. 5. Pike, perch, gudgeon, trout, grayling. II. Milk, cream, butter, buttermilk, whey, cheese. III. Wheat, barley, oats, peas, potatoes, turnips, carrots, cabbage, asparagus, artichoke, spinach, beet, apple, pear, plum, apricot, nectarine, peach, strawberry, grape, orange, melon, cucumber, dried figs, raisins, sugar, honey. With a great variety of other roots, seeds, leaves, and fruits. IV. Water, river-water, spring-water, calcareous earth. V. Air, oxygene, azote, carbonic acid gas. VI. Nutritive baths and clysters, transfusion of blood. VII. Condiments. * * * * * ART. II. INCITANTIA. I. 1. Those things, which increase the exertions of all the irritative motions, are termed incitantia. As alcohol, or the spirituous part of fermented liquors, opium, and many drugs, which are still esteemed poisons, their proper doses not being ascertained. To these should be added the exhilarating passions of the mind, as joy, love: and externally the application of heat, electricity, æther, essential oils, friction, and exercise. 2. These promote both the secretions and absorptions, increase the natural heat, and remove those pains, which originate from the defect of irritative motions, termed nervous pains; and prevent the convulsions consequent to them. When given internally they induce costiveness, and deep coloured urine; and by a greater dose intoxication, and its consequences. II. OBSERVATIONS ON THE INCITANTIA. I. 1. Opium and alcohol increase all the secretions and absorptions. The increase of the secretion of sensorial power appears from the violent exertions of drunken people; the secretion of sweat is more certainly excited by opium or wine than by any other medicine; and the increase of general heat, which these drugs produce, is an evidence of their effect in promoting all the secretions; since an increase of secretion is always attended with increase of heat in the part, as in hepatic and other inflammations. 2. But as they at the same time promote absorption; those fluids, which are secreted into receptacles, as the urine, bile, intestinal and pulmonary mucus, have again their thinner parts absorbed; and hence, though the quantity of secreted fluid was increased, yet as the absorption was also increased, the excretion from these receptacles is lessened; at the same time that it is deeper coloured or of thicker consistence, as the urine, alvine feces, and pulmonary mucus. Whereas the perspiration being secreted on the surface of the body is visible in its increased quantity, before it can be reabsorbed; whence arises that erroneous opinion, that opium increases the cutaneous secretion, and lessens all the others. 3. It must however be noted, that after evacuations opium seems to promote the absorptions more than the secretions; if you except that of the sensorial power in the brain, which probably suffers no absorption. Hence its efficacy in restraining hæmorrhages, after the vessels are emptied, by promoting venous absorption. 4. In ulcers the matter is thickened by the exhibition of opium from the increased absorption of the thinner parts of it; but it is probable, that the whole secretion, including the part which is absorbed, is increased; and hence new fibres are secreted along with the matter, and the ulcer fills with new granulations of flesh. But as no ulcer can heal, till it ceases to discharge; that is, till the absorption becomes as great as the excretion; those medicines, which promote absorption only, are more advantageous for the healing an ulcer after it is filled with new flesh; as the Peruvian bark internally; with bandages and solutions of lead externally. 5. There are many pains which originate from a want of due motion in the part, as those occasioned by cold; and all those pains which are attended with cold extremities, and are generally termed nervous. These are relieved by whatever excites the part into its proper actions, and hence by opium and alcohol; which are the most universal stimulants we are acquainted with. In these cases the effect of opium is produced, as soon as the body becomes generally warm; and a degree of intoxication or sleep follows the cessation of the pain. These nervous pains (as they are called) frequently return at certain periods of time, and are also frequently succeeded by convulsions; in these cases if opium removes the pain, the convulsions do not come on. For this purpose it is best to exhibit it gradually, as a grain every hour, or half hour, till it intoxicates. Here it must be noted, that a much less quantity will prevent the periods of these cold pains, than is necessary to relieve them after their access. As a grain and half of opium given an hour before the expected paroxysm will prevent the cold fit of an intermittent fever, but will not soon remove it, when it is already formed. For in the former case the usual or healthy associations or catenations of motion favour the effect of the medicine; in the latter case these associations or catenations are disordered, or interrupted, and new ones are formed, which so far counteract the effect of the medicine. When opium has been required in large doses to ease or prevent convulsions, some have advised the patient to omit the use of wine, as a greater quantity of opium might then be exhibited; and as opium seems to increase absorption more, and secretion less, than vinous spirit; it may in some cases be useful to exchange one for the other; as in diseases attended with too great evacuation, as diarrhoea, and dysentery, opium may be preferable; on the contrary in tetanus, or locked-jaw, where inflammation of the system might be of service, wine may be preferable to opium; see Class III. 1. 1. 13. I have generally observed, that a mixture of spirit of wine and warm water, given alternately with the doses of opium, has soonest and most certainly produced that degree of intoxication, which was necessary to relieve the patient in the epilepsia dolorifica. 6. There is likewise some relief given by opium to inflammatory pains, or those from excess of motion in the affected part; but with this difference, that this relief from the pains, and the sleep, which it occasions, does not occur till some hours after the exhibition of the opium. This requires to be explained; after the stimulus of opium or of alcohol ceases, as after common drunkenness, a consequent torpor comes on; and the whole habit becomes less irritable by the natural stimuli. Hence the head-achs, sickness, and languor, on the next day after intoxication, with cold skin, and general debility. Now in pains from excess of motion, called inflammatory pains, when opium is given, the pain is not relieved, till the debility comes on after the stimulus ceases to act; for then after the greater stimulus of the opium has exhausted much of the sensorial power; the less stimulus, which before caused the pain, does not now excite the part into unnatural action. In these cases the stimulus of the opium first increases the pain; and it sometimes happens, that so great a torpor follows, as to produce the death or mortification of the affected part; whence the danger of giving opium in inflammatory diseases, especially in inflammation of the bowels; but in general the pain returns with its former violence, when the torpor above mentioned ceases. Hence these pains attended with inflammation are best relieved by copious venesection, other evacuations, and the class of medicines called torpentia. 7. These pains from excess of motion are attended with increased heat of the whole, or of the affected part, and a strong quick pulse; the pains from defect of motion are attended with cold extremities, and a weak pulse; which is also generally more frequent than natural, but not always so. 8. Opium and alcohol are the only two drugs, we are much acquainted with, which intoxicate; and by this circumstance are easily distinguished from the secernentia and sorbentia. Camphor, and cicuta, and nicotiana, are thought to induce a kind of intoxication; and there are many other drugs of this class, whose effects are less known, or their doses not ascertained; as atropa belladonna, hyocyamus, stramonium, prunus laurocerasus, menispermum, cynoglossum, some fungi, and the water distilled from black cherry-stones; the last of which was once much in use for the convulsions of children, and was said to have good effect; but is now improvidently left out of our pharmacopias. I have known one leaf of the laurocerasus, shred and made into tea, given every morning for a week with no ill consequence to a weak hysteric lady, but rather perhaps with advantage. 9. The pernicious effects of a continued use of much vinous spirit is daily seen and lamented by physicians; not only early debility, like premature age, but a dreadful catalogue of diseases is induced by this kind of intemperance; as dropsy, gout, leprosy, epilepsy, insanity, as described in Botanic Garden, Part II. Canto III. line 357. The stronger or less diluted the spirit is taken, the sooner it seems to destroy, as in dram-drinkers; but still sooner, when kernels of apricots, or bitter almonds, or laurel-leaf, are infused in the spirit, which is termed ratafia; as then two poisons are swallowed at the same time. And vinegar, as it contains much vinous spirit, is probably a noxious part of our diet. And the distilled vinegar, which is commonly sold in the shops, is truly poisonous, as it is generally distilled by means of a pewter or leaden alembic-head or worm-tube, and abounds with lead; which any one may detect by mixing with it a solution of liver of sulphur. Opium, when taken as a luxury, not as a medicine, is as pernicious as alcohol; as Baron de Tott relates in his account of the opium-eaters in Turkey. 10. It must be observed, that a frequent repetition of the use of this class of medicines so habituates the body to their stimulus, that their dose may gradually be increased to an astonishing quantity, such as otherwise would instantly destroy life; as is frequently seen in those, who accustom themselves to the daily use of alcohol and opium; and it would seem, that these unfortunate people become diseased as soon as they omit their usual potations; and that the consequent gout, dropsy, palsy, or pimpled face, occur from the debility occasioned from the want of accustomed stimulus, or to some change in the contractile fibres, which requires the continuance or increase of it. Whence the cautions necessary to be observed are mentioned in Sect. XII. 7. 8. 11. It is probable, that some of the articles in the subsequent catalogue do not induce intoxication, though they have been esteemed to do so; as tobacco, hemlock, nux vomica, stavisagria; and on this account should rather belong to other arrangements, as to the secernentia, or sorbentia, or invertentia. II. 1. Externally the application of heat, as the warm bath, by its stimulus on the skin excites the excretory ducts of the perspirative glands, and the mouths of the lymphatics, which open on its surface, into greater action; and in consequence many other irritative motions, which are associated with them. To this increased action is added pleasurable sensation, which adds further activity to the system; and thus many kinds of pain receive relief from this additional atmosphere of heat. The use of a warm bath of about 96 or 98 degrees of heat, for half an hour once a day for three or four months, I have known of great service to weak people, and is perhaps the least noxious of all unnatural stimuli; which however, like all other great excitement, may be carried to excess, as complained of by the ancients. The unmeaning application of the words relaxation and bracing to warm and cold baths has much prevented the use of this grateful stimulus; and the misuse of the term warm-bath, when applied to baths colder than the body, as to those of Buxton and Matlock, and to artificial baths of less than 90 degrees of heat, which ought to be termed cold ones, has contributed to mislead the unwary in their application. The stimulus of wine, or spice, or salt, increases the heat of the system by increasing all or some of the secretions; and hence the strength is diminished afterwards by the loss of fluids, as well as by the increased action of the fibres. But the stimulus of the warm-bath supplies heat rather than produces it; and rather fills the system by increased absorption, than empties it by increased secretion; and may hence be employed with advantage in almost all cases of debility with cold extremities, perhaps even in anasarca, and at the approach of death in fevers. In these cases a bath much beneath 98 degrees, as of 80 or 85, might do injury, as being a cold-bath compared with the heat of the body, though such a bath is generally called a warm one. The activity of the system thus produced by a bath of 98 degrees of heat, or upwards, does not seem to render the patients liable to take cold, when they come out of it; for the system is less inclined to become torpid than before, as the warmth thus acquired by communication, rather than by increased action, continues long without any consequent chillness. Which accords with the observation of Dr. Fordyce, mentioned in Sup. I. 5. 1. who says, that those who are confined some time in an atmosphere of 120 or 130 degrees of heat, do not feel cold or look pale on coming into a temperature of 30 or 40 degrees; which would produce great paleness and sensation of coldness in those, who had been some time confined in an atmosphere of only 86 or 90 degrees of heat. Treatise on Simple Fever, p. 168. Hence heat, where it can be confined on a torpid part along with moisture, as on a scrophulous tumour, will contribute to produce suppuration or resolution. This is done by applying a warm poultice, which should be frequently repeated; or a plaster of resin, wax, or fat; or by covering the part with oiled silk; both which last prevent the perspirable matter from escaping as well as the heat of the part, as these substances repel moisture, and are bad conductors of heat. Another great use of the stimulus of heat is by applying it to torpid ulcers, which are generally termed scrophulous or scorbutic, and are much easier inclined to heal, when covered with several folds of flannel. Mr. ---- had for many months been afflicted with an ulcer in perinæo, which communicated with the urethra, through which a part of his urine was daily evacuated with considerable pain; and was reduced to a great degree of debility. He used a hot-bath of 96 or 98 degrees of heat every day for half an hour during about six months. By this agreeable stimulus repeated thus at uniform times not only the ulcer healed, contrary to the expectation of his friends, but he acquired greater health and strength, than he had for some years previously experienced. Mrs. ---- was affected with transient pains, which were called nervous spasms, and with great fear of diseases, which she did not labour under, with cold extremities, and general debility. She used a hot-bath every other day of 96 degrees of heat for about four months, and recovered a good state of health, with greater strength and courage, than she had possessed for many months before. Mr. Z. a gentleman about 65 years of age, who had lived rather intemperately in respect to vinous potation, and had for many years had annual visits of the gout, which now became irregular, and he appeared to be losing his strength, and beginning to feel the effects of age. He used a bath, as hot as was agreeable to his sensations, twice a week for about a year and half, and greatly recovered his health and strength with less frequent and less violent returns of regular gout, and is now near 80 years of age. When Dr. Franklin, the American philosopher, was in England many years ago, I recommended to him the use of a warm-bath twice a week to prevent the too speedy access of old age, which he then thought that he felt the approach of, and I have been informed, that he continued the use of it till near his death, which was at an advanced age. All these patients were advised not to keep themselves warmer than their usual habits, after they came out of the bath, whether they went into bed or not; as the design was not to promote perspiration, which weakens all constitutions, and seldom is of service to any. Thus a flannel shirt, particularly if it be worn in warm weather, occasions weakness by stimulating the skin by its points into too great action, and producing heat in consequence; and occasions emaciation by increasing the discharge of perspirable matter; and in both these respects differs from the effect of warm bathing, which communicates heat to the system at the same time that it stimulates it, and causes absorption more than exhalation. 2. The effect of the passage of an electric shock through a paralytic limb in causing it to contract, besides the late experiments of Galvani and Volta on frogs, intitle it to be classed amongst universal stimulants. Electric shocks frequently repeated daily for a week or two remove chronical pains, as the pleurodyne chronica, Class I. 2. 4. 14. and other chronic pains, which are termed rheumatic, probably by promoting the absorption of some extravasated material. Scrophulous tumours are sometimes absorbed, and sometimes brought to suppurate by passing electric shocks through them daily for two or three weeks. [Illustration] Miss ----, a young lady about eight years of age, had a swelling about the size of a pigeon's egg on her neck a little below her ear, which long continued in an indolent state. Thirty or forty small electric shocks were passed through it once or twice a day for two or three weeks, and it then suppurated and healed without difficulty. For this operation the coated jar of the electric machine had on its top an electrometer, which measured the shocks by the approach of a brass knob, which communicated with the external coating to another, which communicated with the internal one, and their distance was adjusted by a screw. So that the shocks were so small as not to alarm the child, and the accumulated electricity was frequently discharged, as the wheel continued turning. The tumour was inclosed between two other brass knobs, which were fixed on wires, which passed through glass tubes, the tubes were cemented in two grooves on a board, so that at one end they were nearer each other than at the other, and the knobs were pushed out so far as exactly to include the tumour, as described in the annexed plate, which is about half the size of the original apparatus. Inflammations of the eyes without fever are frequently cured by taking a stream of very small electric sparks from them, or giving the electric sparks to them, once or twice a day for a week or two; that is, the new vessels, which constitute inflammation in these inirritable constitutions, are absorbed by the activity of the absorbents induced by the stimulus of the electric aura. For this operation the easiest method is to fix a pointed wire to a stick of sealing wax, or to an insulating handle of glass, one end of this wire communicates with the prime conductor, and the point is approached near the inflamed eye in every direction. III. Externally the application of ether, and of essential oils, as of cloves or cinnamon, seem to possess a general stimulating effect. As they instantly relieve tooth-ach, and hiccough, when these pains are not in violent degree; and camphor in large doses is said to produce intoxication; this effect however I have not been witness to, and have reason to doubt. The manner in which ether and the essential oil operate on the system when applied externally, is a curious question, as pain is so immediately relieved by them, that they must seem to penetrate by the great fluidity or expansive property of a part of them, as of their odoriferous exhalation or vapour, and that they thus stimulate the torpid part, and not by their being taken up by the absorbent vessels, and carried thither by the long course of circulation; nor is it probable, that these pains are relieved by the sympathy of the torpid membrane with the external skin, which is thus stimulated into action; as it does not succeed, unless it is applied over the pained part. Thus there appears to be three different modes by which extraneous bodies may be introduced into the system, besides that of absorption. 1st. By ethereal transition, as heat and electricity; 2d. by chemical attraction, as oxygen; and 3d. by expansive vapour, as ether and essential oils. IV. The perpetual necessity of the mixture of oxygen gas with the blood in the lungs evinces, that it must act as a stimulus to the sanguiferous system, as the motions of the heart and arteries presently cease, when animals are immersed in airs which possess no oxygen. It may also subsequently answer another important purpose, as it probably affords the material for the production of the sensorial power; which is supposed to be secreted in the brain or medullary part of the nerves; and that the perpetual demand of this fluid in respiration is occasioned by the sensorial power, which is supposed to be produced from it, being too subtle to be long confined in any part of the system. Another proof of the stimulant quality of oxygen appears from the increased acrimony, which the matter of a common abscess possesses, after it has been exposed to the air of the atmosphere, but not before; and probably all other contagious matters owe their fever-producing property to having been converted into acids by their union with oxygen. As oxygen penetrates the fine moist membranes of the air-vessels of the lungs, and unites with the blood by a chemical attraction, as is seen to happen, when blood is drawn into a bason, the lower surface of the crassamentum is of a very dark red so long as it is covered from the air by the upper surface, but becomes florid in a short time on its being exposed to the atmosphere; the manner of its introduction into the system is not probably by animal absorption but by chemical attraction, in which circumstance it differs from the fluids before mentioned both of heat and electricity, and of ether and essential oils. As oxygen has the property of passing through moist animal membranes, as first discovered by the great Dr. Priestley, it is probable it might be of use in vibices, and petechiæ in fevers, and in other bruises; if the skin over those parts was kept moist by warm water, and covered with oxygen gas by means of an inverted glass, or even by exposing the parts thus moistened to the atmosphere, as the dark coloured extravasated blood might thus become florid, and by its increase of stimulus facilitate its reabsorption. Two weak patients, to whom I gave oxygen gas in as pure a state as it can easily be procured from Exeter manganese, and in the quantity of about four gallons a day, seemed to feel refreshed, and stronger, and to look better immediately after respiring it, and gained strength in a short time. Two others, one of whom laboured under confirmed hydrothorax, and the other under a permanent and uniform difficulty of respiration, were not refreshed, or in any way served by the use of oxygen in the above quantity of four gallons a day for a fortnight, which I ascribed to the inirritability of the diseased lungs. For other cases the reader is referred to the publications of Dr. Beddoes; Confederations on the Use of Factitious Airs, sold by Johnson, London. Its effects would probably have been greater in respect to the quantity breathed, if it had been given in a dilute state, mixed with 10 or 20 times its quantity of atmospheric air, as otherwise much of it returns by expiration without being deprived of its quality, as may be seen by the person breathing on the flame of a candle, which it enlarges. See the Treatise of Dr. Beddoes above mentioned. V. Those passions, which are attended with pleasurable sensation, excite the system into increased action in consequence of that sensation, as joy, and love, as is seen by the flush of the skin. Those passions, which are attended with disagreeable sensation, produce torpor in general by the expence of sensorial power occasioned by inactive pain; unless volition be excited in consequence of the painful sensation; and in that case an increased activity of the system occurs; thus paleness and coldness are the consequence of fear, but warmth and redness are the consequence of anger. VI. Besides the exertions of the system occasioned by increased stimuli, and consequent irritation, and by the passions of the mind above described, the increased actions occasioned by exercise belong to this article. These may be divided into the actions of the body in consequence of volition, which is generally termed labour; or secondly, in consequence of agreeable sensation, which is termed play or sport; thirdly, the exercise occasioned by agitation, as in a carriage or on horseback; fourthly, that of friction, as with a brush or hand, so much used in the baths of Turkey; and lastly, the exercise of swinging. The first of these modes of exercise is frequently carried to great excess even amongst our own labourers, and more so under the lash of slavery; so that the body becomes emaciated and sinks under either the present hardships, or by a premature old age. The second mode of exercise is seen in the play of all young animals, as kittens, and puppies, and children; and is so necessary to their health as well as to their pleasure, that those children, which are too much confined from it, not only become pale-faced and bloated, with tumid bellies, and consequent worms, but are liable to get habits of unnatural actions, as twitching of their limbs, or of some parts of their countenance; together with an ill-humoured or discontented mind. Agitation in a carriage or on horseback, as it requires some little voluntary exertion to preserve the body perpendicular, but much less voluntary exertion than in walking, seems the best adapted to invalids; who by these means obtain exercise principally by the strength of the horse, and do not therefore too much exhaust their own sensorial power. The use of friction with a brush or hand, for half an hour or longer morning and evening, is still better adapted to those, who are reduced to extreme debility; and none of their own sensorial power is thus expended, and affords somewhat like the warm-bath activity without self-exertion, and is used as a luxury after warm bathing in many parts of Asia. Another kind of exercise is that of swinging, which requires some exertion to keep the body perpendicular, or pointing towards the center of the swing, but is at the same time attended with a degree of vertigo; and is described in Class II. 1. 6. 7. IV. 2. 1. 10. Sup. I. 3. and 15. The necessity of much exercise has perhaps been more insisted upon by physicians, than nature seems to demand. Few animals exercise themselves so as to induce visible sweat, unless urged to it by mankind, or by fear, or hunger. And numbers of people in our market towns, of ladies particularly, with small fortunes, live to old age in health, without any kind of exercise of body, or much activity of mind. In summer weak people cannot continue too long in the air, if it can be done without fatigue; and in winter they should go out several times in a day for a few minutes, using the cold air like a cold-bath, to invigorate and render them more hardy. III. CATALOGUE OF THE INCITANTIA. I. Papaver somniferum; poppy, opium. Alcohol, wine, beer, cyder. Prunus lauro-cerasus; laurel, distilled water from the leaves. Prunus cerasus; black cherry, distilled water from the kernels. Nicotiana tabacum; tobacco? the essential oil, decoction of the leaf. Atropa belladona; deadly nightshade, the berries. Datura stramoneum; thorn-apple, the fruit boiled in milk. Hyoscyamus reticulatus; henbane, the seeds and leaves. Cynoglossum; hounds tongue. Menispermum, cocculus; Indian berry. Amygdalus amarus; bitter almond. Cicuta; hemlock. Conium maculatum? Strychnos nux vomica? Delphinium stavisagria? II. Externally, heat, electricity. III. Ether, essential oils. IV. Oxygen gas. V. Passions of love, joy, anger. VI. Labour, play, agitation, friction. * * * * * ART. III. SECERNENTIA. I. Those things which increase the irritative motions, which constitute secretion, are termed secernentia; which are as various as the glands, which they stimulate into action. 1. Diaphoretics, as aromatic vegetables, essential oils, ether, volatile alcali, neutral salts, antimonial preparations, external heat, exercise, friction, cold water for a time with subsequent warmth, blisters, electric fluid. 2. Sialagogues, as mercury internally, and pyrethrum externally. 3. Expectorants, as squill, onions, gum ammoniac, seneka root, mucilage: some of these increase the pulmonary perspiration, and perhaps the pulmonary mucus. 4. Diuretics, as neutral salts, fixed alcali, balsams, resins, asparagus, cantharides. 5. Cathartics of the mild kind, as sena, jalap, neutral salts, manna. They increase the secretions of bile, pancreatic juice, and intestinal mucus. 6. The mucus of the bladder is increased by cantharides, and perhaps by oil of turpentine. 7. The mucus of the rectum by aloe internally, by clysters and suppositories externally. 8. The mucus of the cellular membrane is increased by blisters and sinapisms. 9. The mucus of the nostrils is increased by errhines of the milder kind, as marum, common snuff. 10. The secretion of tears is increased by volatile salts, the vapour of onions, by grief, and joy. 11. All those medicines increase the heat of the body, and remove those pains, which originate from a defect of motion in the vessels, which perform secretion; as pepper produces a glow on the skin, and balsam of Peru is said to relieve the flatulent cholic. But these medicines differ from the preceding class, as they neither induce costiveness nor deep coloured urine in their usual dose, nor intoxication in any dose. 12. Yet if any of these are used unnecessarily, it is obvious, like the incitantia, that they must contribute to shorten our lives by sooner rendering peculiar parts of the system disobedient to their natural stimuli. Of those in daily use the great excess of common salt is probably the most pernicious, as it enters all our cookery, and is probably one cause of scrophula, and of sea-scurvy, when joined with other causes of debility. See Botanic Garden, Part II. Canto IV. line 221. Spices taken to excess by stimulating the stomach, and the vessels of the skin by association, into unnecessary action, contribute to weaken these parts of the system, but are probably less noxious than the general use of so much salt. II. OBSERVATIONS ON THE SECERNENTIA. I. 1. Some of the medicines of this class produce absorption in some degree, though their principal effect is exerted on the secerning part of our system. We shall have occasion to observe a similar circumstance in the next class of medicines termed Sorbentia; as of these some exert their effects in a smaller degree on the secerning system. Nor will this surprise any one, who has observed, that all natural objects are presented to us in a state of combination; and that hence the materials, which produce these different effects, are frequently found mingled in the same vegetable. Thus the pure aromatics increase the action of the vessels, which secrete the perspirable matter; and the pure astringents increase the action of the vessels, which absorb the mucus from the lungs, and other cavities of the body; hence it must happen, that nutmeg, which possesses both these qualities, should have the double effect above mentioned. Other drugs have this double effect, and belong either to the class of Secernentia or Sorbentia, according to the dose in which they are exhibited. Thus a small dose of alum increases absorption, and induces costiveness; and a large one increases the secretions into the intestinal canal, and becomes cathartic. And this accounts for the constipation of the belly left after the purgative quality of rhubarb ceases, for it increases absorption in a smaller dose, and secretion in a greater. Hence when a part of the larger dose is carried out of the habit by stools, the small quantity which remains induces costiveness. Hence rhubarb exhibited in small doses, as 2 or 3 grains twice a day, strengthens the system by increasing the action of the absorbent vessels, and of the intestinal canal. 2. Diaphoretics. The perspiration is a secretion from the blood in its passage through the capillary vessels, as other secretions are produced in the termination of the arteries in the various glands. After this secretion the blood loses its florid colour, which it regains in its passage through the lungs; which evinces that something besides water is secreted on the skins of animals. No statical experiments can ascertain the quantity of our perspiration; as a continued absorption of the moisture of the atmosphere exists at the same time both by the cutaneous and pulmonary lymphatics. 3. Every gland is capable of being excited into greater exertions by an appropriated stimulus applied either by its mixture with the blood immediately to the secerning vessel, or applied externally to its excretory duct. Thus mercury internally promotes an increased salivation, and pyrethrum externally applied to the excretory ducts of the salival glands. Aloes stimulate the rectum internally mixed with the circulating blood; and sea-salt by injection externally. Now as the capillaries, which secrete the perspirable matter, lie near the surface of the body, the application of external heat acts immediately on their excretory ducts, and promotes perspiration; internally those drugs which possess a fragrant essential oil, or spiritus rector, produce this effect, as the aromatic vegetables, of which the number is very great. 4. It must be remembered, that a due quantity of some aqueous vehicle must be given to support this evacuation; otherwise a burning heat without much visible sweat must be the consequence. When the skin acquires a degree of heat much above 108, as appears by Dr. Alexander's experiments, no visible sweat is produced; which is owing to the great heat of the skin evaporating it as hastily, as it is secreted; and, where the sweat is secreted in abundance, its evaporation cannot carry off the exuberant heat, like the vapour of boiling water; because a great part of it is wiped off, or absorbed by the bed-clothes; or the air about the patient is not changed sufficiently often, as it becomes saturated with the perspirable matter. And hence it is probable, that the waste of perspirable matter is as great, or greater, when the skin is hot and dry, as when it stands in drops on the skin; as appears from the inextinguishable thirst. Hence Dr. Alexander found, that when the heat of the body was greater than 108, nothing produced sweats but repeated draughts of cold water; and of warm fluids, when the heat was much below that degree. And that cold water which procured sweats instantaneously when the heat was above 108, stopped them as certainly when it was below that heat; and that flannels, wrung out of warm water and wrapped round the legs and thighs, were then most certainly productive of sweats. 5. The diaphoretics are all said to succeed much better, if given early in the morning, about an hour before sun-rise, than at any other time; which is owing to the great excitability of every part of the system after the sensorial power has been accumulated during sleep. In those, who have hectic fever, or the febricula, or nocturnal fever of debility, the morning sweats are owing to the decline of the fever-fit, as explained in Sect. XXXII. 9. In some of these patients the sweat does not occur till they awake; because then the system is still more excitable than during sleep, because the assistance of the voluntary power in respiration facilitates the general circulation. See Class I. 2. 1. 3. 6. It must be observed, that the skin is very dry and hard to the touch, where the absorbents, which open on its surface, do not act; as in some dropsies, and other diseases attended with great thirst. This dryness, and shrivelled appearance, and roughness, are owing to the mouths of the absorbents being empty of their accustomed fluid, and is distinguishable from the dryness of the skin above mentioned in the hot fits of fever, by its not being attended with heat. As the heat of the skin in the usual temperature of the air always evinces an increased perspiration, whether visible or not, the heat being produced along with the increase of secretion; it follows, that a defect of perspiration can only exist, when the skin is cold. 7. Volatile alcali is a very powerful diaphoretic, and particularly if exhibited in wine-whey; 20 drops of spirit of hartshorn every half hour in half a pint of wine-whey, if the patient be kept in a moderately warm bed, will in a few hours elicit most profuse sweats. Neutral salts promote invisible perspiration, when the skin is not warmed much externally, as is evinced from the great thirst, which succeeds a meal of salt provisions, as of red herrings. When these are sufficiently diluted with water, and the skin kept warm, copious sweats without inflaming the habit, are the consequence. Half an ounce of vinegar saturated with volatile alcali, taken every hour or two hours, well answers this purpose; and is preferable perhaps in general to all others, where sweating is advantageous. Boerhaave mentions one cured of a fever by eating red-herrings or anchovies, which, with repeated draughts of warm water or tea, would I suppose produce copious perspiration. Antimonial preparations have also been of late much used with great advantage as diaphoretics. For the history and use of these preparations I shall refer the reader to the late writers on the Materia Medica, only observing that the stomach becomes so soon habituated to its stimulus, that the second dose may be considerably increased, if the first had no operation. Where it is advisable to procure copious sweats, the emetics, as ipecacuanha, joined with opiates, as in Dover's powder, produce this effect with greater certainty than the above. 8. We must not dismiss this subject without observing, that perspiration is designed to keep the skin flexile, as the tears are intended to clean and lubricate the eye; and that neither of these fluids can be considered as excretions in their natural state, but as secretions. See Class I. 1. 2. 3. And that therefore the principal use of diaphoretic medicines is to warm the skin, and thence in consequence to produce the natural degree of insensible perspiration in languid habits. 9. When the skin of the extremities is cold, which is always a sign of present debility, the digestion becomes frequently impaired by association, and cardialgia or heartburn is induced from the vinous or acetous fermentation of the aliment. In this disease diaphoretics, which have been called cordials, by their action on the stomach restore its exertion, and that of the cutaneous capillaries by their association with it, and the skin becomes warm, and the digestion more vigorous. 10. But a blister acts with more permanent and certain effect by stimulating a part of the skin, and thence affecting the whole of it, and of the stomach by association, and thence removes the most obstinate heartburns and vomitings. From this the principal use of blisters is understood, which is to invigorate the exertions of the arterial and lymphatic vessels of the skin, producing an increase of insensible perspiration, and of cutaneous absorption; and to increase the action of the stomach, and the consequent power of digestion; and thence by sympathy to excite all the other irritative motions: hence they relieve pains of the cold kind, which originate from defect of motion; not from their introducing a greater pain, as some have imagined, but by stimulating the torpid vessels into their usual action; and thence increasing the action and consequent warmth of the whole skin, and of all the parts which are associated with it. II. 1. _Sialagogues._ The preparations of mercury consist of a solution or corrosion of that metal by some acid; and, when the dose is known, it is probable that they are all equally efficacious. As their principal use is in the cure of the venereal disease, they will be mentioned in the catalogue amongst the sorbentia. Where salivation is intended, it is much forwarded by a warm room and warm clothes; and prevented by exposing the patient to his usual habits of cool air and dress, as the mercury is then more liable to go off by the bowels. 2. Any acrid drug, as pyrethrum, held in the mouth acts as a sialagogue externally by stimulating the excretory ducts of the salivary glands; and the siliqua hirsuta applied externally to the parotid gland, and even hard substances in the ear, are said to have the same effect. Mastich chewed in the mouth emulges the salivary glands. 3. The unwise custom of chewing and smoking tobacco for many hours in a day not only injures the salivary glands, producing dryness in the mouth when this drug is not used, but I suspect that it also produces schirrhus of the pancreas. The use of tobacco in this immoderate degree injures the power of digestion, by occasioning the patient to spit out that saliva, which he ought to swallow; and hence produces that flatulency, which the vulgar unfortunately take it to prevent. The mucus, which is brought from the fauces by hawking, should be spit out, as well as that coughed up from the lungs; but that which comes spontaneously into the mouth from the salivary glands, should be swallowed mixed with our food or alone for the purposes of digestion. See Class I. 2. 2. 7. III. 1. Expectorants are supposed to increase the secretion of mucus in the branches of the windpipe, or to increase the perspiration of the lungs secreted at the terminations of the bronchial artery. 2. If any thing promotes expectoration toward the end of peripneumonies, when the inflammation is reduced by bleeding and gentle cathartics, small repeated blisters about the chest, with tepid aqueous and mucilaginous or oily liquids, are more advantageous than the medicines generally enumerated under this head; the blisters by stimulating into action the vessels of the skin produce by association a greater activity of those of the mucous membrane, which lines the branches of the windpipe, and air-cells of the lungs; and thus after evacuation they promote the absorption of the mucus and consequent healing of the inflamed membrane, while the diluting liquids prevent this mucus from becoming too viscid for this purpose, or facilitate its expuition. Blisters, one at a time, on the sides or back, or on the sternum, are also useful towards the end of peripneumonies, by preventing the evening access of cold fit, and thence preventing the hot fit by their stimulus on the skin; in the same manner as five drops of laudanum by its stimulus on the stomach. For the increased actions of the vessels of the skin or stomach excite a greater quantity of the sensorial power of association, and thus prevent the torpor of the other parts of the system; which, when patients are debilitated, is so liable to return in the evening. 3. Warm bathing is of great service towards the end of peripneumony to promote expectoration, especially in those children who drink too little aqueous fluids, as it gently increases the action of the pulmonary capillaries by their content with the cutaneous ones, and supplies the system with aqueous fluid, and thus dilutes the secreted mucus. Some have recommended oil externally around the chest, as well as internally, to promote expectoration; and upon the nose, when its mucous membrane is inflamed, as in common catarrh. IV. 1. Diuretics. If the skin be kept warm, most of these medicines promote sweat instead of urine; and if their dose is enlarged, most of them become cathartic. Hence the neutral salts are used in general for all these purposes. Those indeed, which are composed of the vegetable acid, are most generally used as sudorifics; those with the nitrous acid as diuretics; and those with the vitriolic acid as cathartics: while those united with the marine acid enter our common nutriment, as a more general stimulus. All these increase the acrimony of the urine, hence it is retained a less time in the bladder; and in consequence less of it is reabsorbed into the system, and the apparent quantity is greater, as more is evacuated from the bladder; but it is not certain from thence, that a greater quantity is secreted by the kidnies. Hence nitre, and other neutral salts, are erroneously given in the gonorrhoea; as they augment the pain of making water by their stimulus on the excoriated or inflamed urethra. They are also erroneously given in catarrhs or coughs, where the discharge is too thin and saline, as they increase the frequency of coughing. 2. Balsam of Copaiva is thought to promote urine more than the other native balsams; and common resin is said to act as a powerful diuretic in horses. These are also much recommended in gleets, and in fluor albus, perhaps more than they deserve; they give a violet smell to the urine, and hence probably increase the secretion of it. Calcined egg-shells are said to promote urine, perhaps from the phosphoric acid they contain. 3. Cold air and cold water will increase the quantity of urine by decreasing the absorption from the bladder; and neutral and alcalious salts and cantharides by stimulating the neck of the bladder to discharge the urine as soon as secreted; and alcohol as gin and rum at the beginning of intoxication, if the body be kept cool, occasion much urine by inverting the urinary lymphatics, and thence pouring a fluid into the bladder, which never passed the kidnies. But it is probable, that those medicines, which give a scent to the urine as the balsams and resins, but particularly asparagus and garlic, are the only drugs, which truly increase the secretion of the kidnies. Alcohol however, used as above mentioned, and perhaps great doses of tincture of cantharides, may be considered as drastic diuretics, as they pour a fluid into the bladder by the retrograde action of the lymphatics, which are in great abundance spread about the neck of it. See Sect. XXIX. 3. V. Mild cathartics. The ancients believed that some purges evacuated the bile, and hence were termed Cholagogues; others the lymph, and were termed Hydragogues; and that in most each cathartic selected a peculiar humour, which it discharged. The moderns have too hastily rejected this system; the subject well deserves further observation. Calomel given in the dose from ten to twenty grains, so as to induce purging without the assistance of other drugs, appears to me to particularly increase the secretion of bile, and to evacuate it; aloe seems to increase the secretion of the intestinal mucus; and it is probable that the pancreas and spleen may be peculiarly stimulated into action by some other of this tribe of medicines; whilst others of them may simply stimulate the intestinal canal to evacuate its contents, as the bile of animals. It must be remarked, that all these cathartic medicines are supposed to be exhibited in their usual doses, otherwise they become drastic purges, and are treated of in the Class of Invertentia. VI. The mucus of the bladder is seen in the urine, when cantharides have been used, either internally or externally, in such doses as to induce the strangury. Spirit of turpentine is said to have the same effect. I have given above a dram of it twice a day floating on a glass of water in chronic lumbago without this effect, and the patient gradually recovered. VII. Aloe given internally seems to act chiefly on the rectum and, spincter ani, producing tenesmus and piles. Externally in clysters or suppositories, common salt seems to act on that bowel with greater certainty. But where the thread-worm or ascarides exist, 60 or 100 grains of aloes reduced to powder and boiled in a pint of gruel, and used as a clyster twice a week for three months, has frequently destroyed them. VIII. The external application of cantharides by stimulating the excretory ducts of the capillary glands produces a great secretion of subcutaneous mucus with pain and inflammation; which mucaginous fluid, not being able to permeate the cuticle, raises it up; a similar secretion and elevation of the cuticle is produced by actual fire; and by caustic materials, as by the application of the juice of the root of white briony, or bruised mustard-seed. Experiments are wanting to introduce some acrid application into practice instead of cantharides, which might not induce the strangury. Mustard-seed alone is too acrid, and if it be suffered to lie on the skin many minutes is liable to produce a slough and consequent ulcer, and should therefore be mixed with flour when applied to cold extremities. Volatile alkali properly diluted might stimulate the skin without inducing strangury. IX. The mild errhines are such as moderately stimulate the membrane of the nostrils, so as to increase the secretion of nasal mucus; as is seen in those, who are habituated to take snuff. The stronger errhines are mentioned in Art. V. 2. 3. X. The secretion of tears is increased either by applying acrid substances to the eye; or acrid vapours, which stimulate the excretory duct of the lacrymal gland; or by applying them to the nostrils, and stimulating the excretory duct of the lacrymal sack, as treated of in the Section on Instinct. Or the secretion of tears is increased by the association of the motions of the excretory duct of the lacrymal sack with ideas of tender pleasure, or of hopeless distress, as explained in Sect. XVI. 8. 2. and 3. XI. The secretion of sensorial power in the brain is probably increased by opium or wine, because when taken in certain quantity an immediate increase of strength and activity succeeds for a time, with consequent debility if the quantity taken be so great as to intoxicate in the least degree. The necessity of perpetual respiration shews, that the oxygen of the atmosphere supplies the source of the spirit of animation; which is constantly expended, and is probably too fine to be long contained in the nerves after its production in the brain. Whence it is probable, that the respiration of oxygen gas mixed with common air may increase the secretion of sensorial power; as indeed would appear from its exhilarating effect on most patients. III. CATALOGUE OF THE SECERNENTIA. I. Diaphoretics. 1. Amomum zinziber, ginger. Caryophyllus aromaticus, cloves. Piper indicum, pepper. Capsicum. Cardamomum. Pimento, myrtus pimenta. Canella alba. Serpentaria virginiana, aristolochia serpentaria, guaiacum. Sassafras, laurus sassafras. Opium. Wine. 2. Essential oils of cinnamon, laurus cinnamomum. Nutmeg, myristica moschata. Cloves, caryophyllus aromaticus. Mint, mentha. Camphor, laurus camphora. Ether. 3. Volatile salts, as of ammoniac and of hartshorn. Sal cornu cervi. 4. Neutral salts, as those with vegetable acid; or with marine acid, as common salt. Halex. Red-herring, anchovy. 5. Preparations of antimony, as emetic tartar, antimonium tartarizatum, wine of antimony. James's powder. 6. External applications. Blisters. Warm bath. Warm air. Exercise. Friction. 7. Cold water with subsequent warmth. II. Sialagogues. Preparations of mercury, hydrargyrus. Pyrethrum, anthemis pyrethrum, tobacco, cloves, pepper, cowhage, stizolobium siliqua hirsuta. Mastich, pistacia lentiscus. III. Expectorants: 1. Squill, scilla maritima, garlic, leek, onion, allium, asafoetida, ferula asafoetida, gum ammoniac, benzoin, tar, pix liquida, balsam of Tolu. 2. Root of seneka, polygala seneka, of elicampane, inula helenium. 3. Marsh-mallow, althæa, coltsfoot, tussilago farfara, gum arabic, mimosa nilotica, gum tragacanth, astragalus tragacantha. Decoction of barley, hordeum distichon. Expressed oils. Spermaceti, soap. Extract of liquorice, glycyrrhiza glabra. Sugar. Honey. 4. Externally blisters. Oil. Warm bath. IV. Mild diuretics. 1. Nitre, kali acetatum, other neutral salts. 2. Fixed alkali, soap, calcined egg-shells. 3. Turpentine. Balsam of Copaiva. Resin. Olibanum. 4. Asparagus, garlic, wild daucus. Parsley, apium. Fennel fæniculum, pareira brava, Cissampelos? 5. Externally cold air, cold water. 6. Alcohol. Tincture of cantharides. Opium. V. Mild cathartics. 1. Sweet subacid fruits. Prunes, prunus domestica. Cassia sistula. Tamarinds, crystals of tartar, unrefined sugar. Manna. Honey. 2. Whey of milk, bile of animals. 3. Neutral salts, as Glauber's salt, vitriolated tartar, sea-water, magnesia alba, soap. 4. Gum guaiacum. Balsam of Peru. Oleum ricini, castor-oil, oil of almonds, oil of olives, sulphur. 5. Senna, cassia senna, jalap, aloe, rhubarb, rheum palmatum. 6. Calomel. Emetic tartar, antimonium tartarizatum. VI. Secretion of mucus of the bladder is increased by cantharides, by spirit of turpentine? VII. Secretion of mucus of the rectum is increased by aloe internally, by various clysters and suppositories externally. VIII. Secretion of subcutaneous mucus is increased by blisters of cantharides, by application of a thin slice of the fresh root of white briony, by sinapisms, by root of horse-radish, cochlearia armoracia. Volatile alcali. IX. Mild errhines. Marjoram. Origanum. Marum, tobacco. X. Secretion of tears is increased by vapour of sliced onion, of volatile alcali. By pity, or ideas of hopeless distress. XI. Secretion of sensorial power in the brain is probably increased by opium, by wine, and perhaps by oxygen gas added to the common air in respiration. * * * * * ART. IV. SORBENTIA. I. Those things which increase the irritative motions, which constitute absorption, are termed sorbentia; and are as various as the absorbent vessels, which they stimulate into action. 1. Cutaneous absorption is increased by austere acids, as of vitriol; hence they are believed to check colliquative sweats, and to check the eruption of small-pox, and contribute to the cure of the itch, and tinea; hence they thicken the saliva in the mouth, as lemon-juice, crab-juice, sloes. 2. Absorption from the mucous membrane is increased by opium, and Peruvian bark, internally; and by blue vitriol externally. Hence the expectoration in coughs, and the mucous discharge from the urethra, are thickened and lessened. 3. Absorption from the cellular membrane is promoted by bitter vegetables, and by emetics, and cathartics. Hence matter is thickened and lessened in ulcers by opium and Peruvian bark; and serum is absorbed in anasarca by the operation of emetics and cathartics. 4. Venous absorption is increased by acrid vegetables; as water-cress, cellery, horse-radish, mustard. Hence their use in sea-scurvy, the vibices of which are owing to a defect of venous absorption; and by external stimulants, as vinegar, and by electricity, and perhaps by oxygen. 5. Intestinal absorption is increased by astringent vegetables, as rhubarb, galls; and by earthy salts, as alum; and by argillaceous and calcareous earth. 6. Hepatic absorption is increased by metallic salts, hence calomel and sal martis are so efficacious in jaundice, worms, chlorosis, dropsy. 7. Venereal virus in ulcers is absorbed by the stimulus of mercury; hence they heal by the use of this medicine. 8. Venesection, hunger, thirst, and violent evacuations, increase all absorptions; hence sweating produces costiveness. 9. Externally bitter astringent vegetables, earthy and metallic salts, and bandages, promote the absorption of the parts on which they are applied. 10. All these in their usual doses do not increase the natural heat; but they induce costiveness, and deep coloured urine with earthy sediment. In greater doses they invert the motions of the stomach and lacteals; and hence vomit or purge, as carduus benedictus, rhubarb. They promote perspiration, if the skin be kept warm; as camomile tea, and testaceous powders, have been used as sudorifics. The preparations of antimony vomit, purge, or sweat, either according to the quantity exhibited, or as a part of what is given is evacuated. Thus a quarter of a grain of emetic tartar (if well prepared) will promote a diaphoresis, if the skin be kept warm; half a grain will procure a stool or two first, and sweating afterwards; and a grain will generally vomit, and then purge, and lastly sweat the patient. In less quantity it is probable, that this medicine acts like other metallic salts, as steel, zinc, or copper in small doses; that is, that it strengthens the system by its stimulus. As camomile or rhubarb in different doses vomit, or purge, or act as stimulants so as to strengthen the system. II. OBSERVATIONS ON THE SORBENTIA. I. 1. As there is great difference in the apparent structure of the various glands, and of the fluids which they select from the blood, these glands must possess different kinds of irritability, and are therefore stimulated into stronger or unnatural actions by different articles of the materia medica, as shewn in the secernentia. Now as the absorbent vessels are likewise glands, and drink up or select different fluids, as chyle, water, mucus, with a part of every different secretion, as a part of the bile, a part of the saliva, a part of the urine, &c. it appears, that these absorbent vessels must likewise possess different kinds of irritability, and in consequence must require different articles of the materia medica to excite them into unusual action. This part of the subject has been so little attended to, that the candid reader will find in this article a great deal to excuse. It was observed, that some of the secernentia did in a less degree increase absorption, from the combination of different properties in the same vegetable body; for the same reason some of the class of sorbentia produce secretion in a less degree, as those bitters which have also an aroma in their composition; these are known from their increasing the heat of the system above its usual degree. It must also be noted, that the actions of every part of the absorbent system are so associated with each other, that the drugs which stimulate one branch increase the action of the whole; and the torpor or quiescence of one branch weakens the exertions of the whole; or when one branch is excited into stronger action, some other branch has its actions weakened or inverted. Yet though peculiar branches of the absorbent system are stimulated into action by peculiar substances, there are other substances which seem to stimulate the whole system, and that without immediately increasing any of the secretions; as those bitters which possess no aromatic scent, at the head of which stands the famed Peruvian bark, or cinchona. 2. Cutaneous absorption. I have heard of some experiments, in which the body was kept cold, and was thought to absorb more moisture from the atmosphere than at any other time. This however cannot be determined by statical experiments; as the capillary vessels, which secrete the perspirable matter, must at the same time have been benumbed by the cold; and from their inaction there could not have been the usual waste of the weight of the body; and as all other muscular exertions are best performed, when the body possesses its usual degree of warmth, it is conclusive, that the absorbent system should likewise do its office best, when it is not benumbed by external cold. The austere acids, as of vitriol, lemon-juice, juice of crabs and sloes, strengthen digestion, and prevent that propensity to sweat so usual to weak convalescents, and diminish the colliquative sweats in hectic fevers; all which are owing to their increasing the action of the external and internal cutaneous absorption. Hence vitriolic acid is given in the small-pox to prevent the too hasty or too copious eruption, which it effects, by increasing the cutaneous absorption. Vinegar, from the quantity of alcohol which it contains, exerts a contrary effect to that here described, and belongs to the incitantia; as an ounce of it promotes sweat, and a flushing of the skin; at the same time externally it acts as a venous absorbent, as the lips become pale by moistening them with it. And it is said, when taken internally in great and continued quantity, to induce paleness of the skin, and softness of the bones. The sweet vegetable acids, as of several ripe fruits, are among the torpentia; as they are less stimulating than the general food of this climate, and are hence used in inflammatory diseases. Where the quantity of fluids in the system is much lessened, as in hectic fever, which has been of some continuance, or in spurious peripneumony, a grain of opium given at night will sometimes prevent the appearance of sweats; which is owing to the stimulus of opium increasing the actions of the cutaneous absorbents, more than those of the secerning vessels of the skin. Whence the secretion of perspirable matter is not decreased, but its appearance on the skin is prevented by its more facile absorption. 3. There is one kind of itch, which seldom appears between the fingers, is the least infectious, and most difficult to eradicate, and which has its cure much facilitated by the internal use of acid of vitriol. This disease consists of small ulcers in the skin, which are healed by whatever increases the cutaneous absorption. The external application of sulphur, mercury, and acrid vegetables, acts on the same principle; for the animalcula, which are seen in these pustules, are the effect, not the cause, of them; as all other stagnating animal fluids, as the semen itself, abounds with similar microscopic animals. 4. Young children have sometimes an eruption upon the head called Tinea, which discharges an acrimonius ichor inflaming the parts, on which it falls. This eruption I have seen submit to the internal use of vitriolic acid, when only wheat-flour was applied externally. This kind of eruption is likewise frequently cured by testaceous powders; two materials so widely different in their chemical properties, but agreeing in their power of promoting cutaneous absorption. II. Absorption from the mucous membrane is increased by applying to its surface the austere acids, as of vitriol, lemon-juice, crab-juice, sloes. When these are taken into the mouth, they immediately thicken, and at the same time lessen the quantity of the saliva; which last circumstance cannot be owing to their coagulating the saliva, but to their increasing the absorption of the thinner parts of it. So alum applied to the tip of the tongue does not stop in its action there, but independent of its diffusion it induces cohesion and corrugation over the whole mouth. (Cullen's Mat. Med. Art. Astringentia.) Which is owing to the association of the motions of the parts or branches of the absorbent system with each other. Absorption from the mucous membrane is increased by opium taken internally in small doses more than by any other medicine, as is seen in its thickening the expectoration in coughs, and the discharge from the nostrils in catarrh, and perhaps the discharge from the urethra in gonorrhoea. The bark seems next in power for all these purposes. Externally slight solutions of blue vitriol, as two or three grains to an ounce of water, applied to ulcers of the mouth, or to chancres on the glans penis, more powerfully induces them to heal than any other material. Where the lungs or urethra are inflamed to a considerable degree, and the absorption is so great, that the mucus is already too thick, and adheres to the membrane from its viscidity, opiates and bitter vegetable and austere acids are improper; and mucilaginous diluents should be used in their stead with venesection and torpentia. III. 1. Absorption from the cellular membrane, and from all the other cavities of the body, is too slowly performed in some constitutions; hence the bloated pale complexion; and when this occurs in its greatest degree, it becomes an universal dropsy. These habits are liable to intermittent fevers, hysteric paroxysms, cold extremities, indigestion, and all the symptoms of debility. The absorbent system is more subject to torpor or quiescence than the secerning system, both from the coldness of the fluids which are applied to it, as the moisture of the atmosphere, and from the coldness of the fluids which we drink; and also from its being stimulated only by intervals, as when we take our food; whereas the secerning system is perpetually excited into action by the warm circulating blood; as explained in Sect. XXXII. 2. The Peruvian bark, camomile flowers, and other bitter drugs, by stimulating this cellular branch of the absorbent system prevents it from becoming quiescent; hence the cold paroxysms of those agues, which arise from the torpor of the cellular lymphatics, are prevented, and the hot fits in consequence. The patient thence preserves his natural heat, regains his healthy colour, and his accustomed strength. Where the cold paroxysm of an ague originates in the absorbents of the liver, spleen, or other internal viscus, the addition of steel to vegetable bitters, and especially after the use of one dose of calomel, much advances the cure. And where it originates in any part of the secerning system, as is probably the case in some kinds of agues, the addition of opium in the dose of a grain and half, given about an hour before the access of the paroxysm, or mixed with chalybeate and bitter medicines, ensures the cure. Or the same may be effected by wine given instead of opium before the paroxysm, so as nearly to intoxicate. These three kinds of agues are thus distinguished; the first is not attended with any tumid or indurated viscus, which the people call an ague cake, and which is evident to the touch. The second is accompanied with a tumid viscus; and the last has generally, I believe, the quartan type, and is attended with some degree of arterial debility. 3. This class of absorbent medicines are said to decrease irritability. After any part of our system has been torpid or quiescent, by whatever cause that was produced, it becomes afterwards capable of being excited into greater motion by small stimuli; hence the hot fit of fever succeeds the cold one. As these medicines prevent torpor or quiescence of parts of the system, as cold hands or feet, which perpetually happen to weak constitutions, the subsequent increase of irritability of these parts is likewise prevented. 4. These absorbent medicines, including both the bitters, and metallic salts, and opiates, are of great use in the dropsy by their promoting universal absorption; but here evacuations are likewise to be produced, as will be treated of in the Invertentia. 5. The matter in ulcers is thickened, and thence rendered less corrosive, the saline part of it being reabsorbed by the use of bitter medicines; hence the bark is used with advantage in the cure of ulcers. 6. Bitter medicines strengthen digestion by promoting the absorption of chyle; hence the introduction of hop into the potation used at our meals, which as a medicine may be taken advantageously, but, like other unnecessary stimuli, must be injurious as an article of our daily diet. The hop may perhaps in some degree contribute to the production of gravel in the kidnies, as our intemperate wine-drinkers are more subject to the gout, and ale-drinkers to the gravel; in the formation of both which diseases, there can be no doubt, but that the alcohol is the principal, if not the only agent. 7. Vomits greatly increase the absorption from the cellular membrane, as squill, and foxglove. The squill should be given in the dose of a grain of the dried root every hour, till it operates upwards and downwards. Four ounces of the fresh leaves of the foxglove should be boiled from two pounds of water to one, and half an ounce of the decoction taken every two hours for four or more doses. This medicine by stimulating into inverted action the absorbents of the stomach, increases the direct action of the cellular lymphatics. Another more convenient way of ascertaining the dose of foxglove is by making a saturated tincture of it in proof spirit; which has the twofold advantage of being invariable in its original strength, and of keeping a long time as a shop-medicine without losing any of its virtue. Put two ounces of the leaves of purple foxglove, digitalis purpurea, nicely dried, and coarsely powdered, into a mixture of four ounces of rectified spirit of wine and four ounces of water; let the mixture stand by the fire-side twenty-four hours frequently shaking the bottle, and thus making a saturated tincture of digitalis; which must be poured from the sediment or passed through filtering paper. As the size of a drop is greater or less according to the size of the rim of the phial from which it is dropped, a part of this saturated tincture is then directed to be put into a two-ounce phial, for the purpose of ascertaining the size of the drop. Thirty drops of this tincture is directed to be put into an ounce of mint-water for a draught to be taken twice or thrice a day, till it reduces the anasarca of the limbs, or removes the difficulty of breathing in hydrothorax, or till it induces sickness. And if these do not occur in two or three days, the dose must be gradually increased to forty or sixty drops, or further. From the great stimulus of this medicine the stomach is rendered torpid with consequent sickness, which continues many hours and even days, owing to the great exhaustion of its sensorial power of irritation; and the action of the heart and arteries becomes feeble from the deficient excitement of the sensorial power of association; and lastly, the absorbents of the cellular membrane act more violently in consequence of the accumulation of the sensorial power of association in the torpid heart and arteries, as explained in Suppl. I. 12. A circumstance curiously similar to this occurs to some people on smoking tobacco for a short time, who have not been accustomed to it. A degree of sickness is presently induced, and the pulsations of the heart and arteries become feeble for a short time, as in the approach to fainting, owing to the direct sympathy between these and the stomach, that is from defect of the excitement of the power of association. Then there succeeds a tingling, and heat, and sometimes sweat, owing to the increased action of the capillaries, or perspirative and mucous glands; which is occasioned by the accumulation of the sensorial power of association by the weaker action of the heart and arteries, which now increases the action of the capillaries. 8. Another method of increasing absorption from the cellular membrane is by warm air, or by warm steam. If the swelled legs of a dropsical patient are inclosed in a box, the air of which is made warm by a lamp or two, copious sweats are soon produced by the increased action of the capillary glands, which are seen to stand on the skin, as it cannot readily exhale in so small a quantity of air, which is only changed so fast as may be necessary to permit the lamps to burn. At the same time the lymphatics of the cellular membrane are stimulated by the heat into greater action, as appears by the speedy reduction of the tumid legs. It would be well worth trying an experiment upon a person labouring under a general anasarca by putting him into a room filled with air heated to 120 or 130 degrees, which would probably excite a great general diaphoresis, and a general cellular absorption both from the lungs and every other part. And that air of so great heat may be borne for many minutes without great inconvenience was shewn by the experiments made in heated rooms by Dr. Fordyce and others. Philos. Trans. Another experiment of using warmth in anasarca, or in other diseases, might be by immersing the patient in warm air, or in warm steam, received into an oil-skin bag, or bathing-tub of tin, so managed, that the current of warm air or steam should pass round and cover the whole of the body except the head, which might not be exposed to it; and thus the absorbents of the lungs might be induced to act more powerfully by sympathy with the skin, and not by the stimulus of heat. See Uses of Warm Bath, Art. II. 2. 2. 1. IV. 1. Venous absorption. Cellary, water-cresses, cabbages, and many other vegetables of the Class Tetradynamia, do not increase the heat of the body (except those whose acrimony approaches to corrosion), and hence they seem alone, or principally, to act on the venous system; the extremities of which we have shewn are absorbents of the red blood, after it has passed the capillaries and glands. 2. In the sea-scurvy and petechial fever the veins do not perfectly perform this office of absorption; and hence the vibices are occasioned by blood stagnating at their extremities, or extravasated into the cellular membrane. And this class of vegetables, stimulating the veins to perform their natural absorption, without increasing the energy of the arterial action, prevents future petechiæ, and may assist the absorption of the blood already stagnated, as soon as its chemical change renders it proper for that operation. 3. The fluids, which are extravasated, and received into the cells of the cellular membrane, seem to continue there for many days, so as to undergo some chemical change, and are then taken up again by the mouths of the cellular absorbents. But the new vessels produced in inflamed parts, as they communicate with the veins, are probably absorbed again by the veins along with the blood which they contain in their cavities. Hence the blood, which is extravasated in bruises or vibices, is gradually many days in disappearing; but after due evacuations the inflamed vessels on the white of the eye, if any stimulant lotion is applied, totally disappear in a few hours. Amongst absorbents affecting the veins we should therefore add the external application of stimulant materials; as of vinegar, which makes the lips pale on touching them. Friction, and electricity. 4. Hæmorrhages are of two kinds, either arterial, which are attended with inflammation; or venous, from a deficiency in the absorbent power of this set of vessels. In the former case the torpentia are efficacious; in the latter steel, opium, alum, and all the tribe of sorbentia, are used with success. 5. Sydenham recommends vegetables of the class Tetradynamia in rheumatic pains left after the cure of intermittents. These pains are perhaps similar to those of the sea-scurvy, and seem to arise from want of absorption in the affected part, and hence are relieved by the same medicines. V. 1. Intestinal absorption. Some astringent vegetables, as rhubarb, may be given in such doses as to prove cathartic; and, after a part of it is evacuated from the body, the remaining part augments the absorption of the intestines; and acts, as if a similar dose had been exhibited after the operation of any other purgative. Hence 4 grains of rhubarb strengthen the bowels, 30 grains first empty them. 2. The earthy salts, as alum, increase the intestinal absorption, and hence induce constipation in their usual dose; alum is said sometimes to cure intermittents, perhaps when their seat is in the intestines, when other remedies have failed. It is useful in the diabætes by exciting the absorbents of the bladder into their natural action; and combined with resin is esteemed in the fluor albus, and in gleets. Lime-stone or chalk, and probably gypsum, possess effects in some degree similar, and increase the absorption of the intestines; and thus in certain doses restrain some diarrhoeas, but in greater doses alum I suppose will act as a cathartic. Five or ten grains produce constipation, 20 or 30 grains are either emetic or cathartic. 3. Earth of alum, tobacco-pipe clay, marl, Armenian bole, lime, crab's eyes or claws, and calcined hartshorn, or bone ashes, restrain fluxes; either mechanically by supplying something like mucilage, or oil, or rollers to abate the friction of the aliment over inflamed membranes; or by increasing their absorption. The two last consist of calcareous earth united to phosphoric acid, and the Armenian bole and marl may contain iron. By the consent between the intestines and the skin 20 grains of Armenian bole given at going into bed to hectic patients will frequently check their tendency to sweat as well as to purge, and the more certainly if joined with one grain of opium. VI. 1. Absorption from the liver, stomach, and other viscera. When inflammations of the liver are subdued to a certain degree by venesection, with calomel and other gentle purges, so that the arterial energy becomes weakened, four or eight grains of iron-filings, or of salt of steel, with the Peruvian bark, have wonderful effect in curing the cough, and restoring the liver to its usual size and sanity; which it seems to effect by increasing the absorption of this viscus. The same I suppose happens in respect to the tumours of other viscera, as of the spleen, or pancreas, some of which are frequently enlarged in agues. 2. Hæmorrhages from the nose, rectum, kidnies, uterus, and other parts, are frequently attendant on diseased livers; the blood being impeded in the vena portarum from the decreased power of absorption, and in consequence of the increased size of this viscus. These hæmorrhages after venesection, and a mercurial cathartic, are most certainly restrained by steel alone, or joined with an opiate; which increase the absorption, and diminish the size of the liver. Chalybeates may also restrain these hæmorrhages by their promoting venous absorption, though they exert their principal effect upon the liver. Hence also opiates, and bitters, and vitriolic acid, are advantageously used along with them. It must be added that some hæmorrhages recur by periods like the paroxysms of intermittent fevers, and are thence cured by the same treatment. 3. The jaundice is frequently caused by the insipidity of the bile, which does not stimulate the gall-bladder and bile-ducts into their due action; hence it stagnates in the gall-bladder, and produces a kind of crystallization, which is too large to pass into the intestines, blocks up the bile-duct, and occasions a long and painful disease. A paralysis of the bile duct produces a similar jaundice, but without pain. 4. Worms in sheep called flukes are owing to the dilute state of the bile; hence they originate in the intestines, and thence migrate into the biliary ducts, and corroding the liver produce ulcers, cough, and hectic fever, called the rot. In human bodies it is probable the inert state of the bile is one cause of the production of worms; which insipid state of the bile is owing to deficient absorption of the thinner parts of it; hence the pale and bloated complexion, and swelled upper lip, of wormy children, is owing to the concomitant deficiency of absorption from the cellular membrane. Salt of steel, or the rust of it, or filings of it, with bitters, increase the acrimony of the bile by promoting the absorption of its aqueous part; and hence destroy worms, as well as by their immediate action on the intestines, or on the worms themselves. The cure is facilitated by premising a purge with calomel. See Class I. 2. 3. 9. 5. The chlorosis is another disease owing to the deficient action of the absorbents of the liver, and perhaps in some degree also to that of the secretory vessels, or glands, which compose that viscus. Of this the want of the catameniæ, which is generally supposed to be a cause, is only a symptom or consequence. In this complaint the bile is deficient perhaps in quantity, but certainly in acrimony, the thinner parts not being absorbed from it. Now as the bile is probably of great consequence in the process of making the blood; it is on this account that the blood is so destitute of red globules; which is evinced by the great paleness of these patients. As this serous blood must exert less stimulus on the heart, and arteries, the pulse in consequence becomes quick as well as weak, as explained in Sect. XII. 1. 4. The quickness of the pulse is frequently so great and permanent, that when attended by an accidental cough, the disease may be mistaken for hectic fever; but is cured by chalybeates, and bitters exhibited twice a day; with half a grain of opium, and a grain of aloe every night; and the expected catamenia appears in consequence of a restoration of the due quantity of red blood. This and the two former articles approach to the disease termed paralysis of the liver. Sect. XXX. 1. 4. 6. It seems paradoxical, that the same treatment with chalybeates, bitters, and opiates, which produces menstruation in chlorotic patients, should repress the too great or permanent menstruation, which occurs in weak constitutions at the time of life when it should cease. This complaint is an hæmorrhage owing to the debility of the absorbent power of the veins, and belongs to the paragraph on venous absorption above described, and is thence curable by chalybeates, alum, bitters, and particularly by the exhibition of a grain of opium every night with five grains of rhubarb. 7. Metallic salts supply us with very powerful remedies for promoting absorption in dropsical cases; which frequently are caused by enlargement of the liver. First, as they may be given in such quantities as to prove strongly cathartic, of which more will be said in the article on invertentia; and then, when their purgative quality ceases, like the effect of rhubarb, their absorbent quality continues to act. The salts of mercury, silver, copper, iron, zinc, antimony, have all been used in the dropsy; either singly for the former purpose, or united with bitters for the latter, and occasionally with moderate but repeated opiates. 8. From a quarter of a grain to half a grain of blue vitriol given every four or six hours, is said to be very efficacious in obstinate intermittents; which also frequently arise from an enlarged viscus, as the liver or spleen, and are thence owing to the deficient absorption of the lymphatics of that viscus. A quarter of a grain of white arsenic, as I was informed by a surgeon of the army, cures a quartan ague with great certainty, if it be given an hour before the expected fit. This dose he said was for a robust man, perhaps one eighth of a grain might be given and repeated with greater safety and equal efficacy. Dr. Fowler has given many successful cases in his treatise on this subject. He prepares it by boiling sixty-four grains of white arsenic in a Florence flask along with as much pure vegetable fixed alcali in a pint of distilled water, till it is dissolved, and then adding to it as much distilled water as will make the whole exactly sixteen ounces. Hence there are four grains of arsenic in every ounce of the solution. This should be put into a phial of such a size of the edge of its aperture, that sixty drops may weigh one dram, which will contain half a grain of arsenic. To children from two years old to four he gives from two to five drops three or four times a day. From five years old to seven, he directs seven or eight drops. From eight years old to twelve, he directs from seven to ten drops. From thirteen years old to eighteen he directs from ten to twelve drops. From eighteen upwards, twelve drops. In so powerful a medicine it is always prudent to begin with smaller doses, and gradually to increase them. A saturated solution of arsenic in water is preferable I think to the above operose preparation of it; as no error can happen in weighing the ingredients, and it more certainly therefore possesses an uniform strength. Put much more white arsenic reduced to powder into a given quantity of distilled water, than can be dissolved in it. Boil it for half an hour in a Florence flask, or in a tin sauce-pan; let it stand to subside, and filter it through paper. My friend Mr. Greene, a surgeon at Brewood in Staffordshire, assured me, that he had cured in one season agues without number with this saturated solution; that he found ten drops from a two-ounce phial given thrice a day was a full dose for a grown person, but that he generally began with five. 9. The manner, in which arsenic acts in curing intermittent fevers, cannot be by its general stimulus, because no intoxication or heat follows the use of it; nor by its peculiar stimulus on any part of the secreting system, since it is not in small doses succeeded by any increased evacuation, or heat, and must therefore exert its power, like other articles of the sorbentia, on the absorbent system. In what manner it destroys life so suddenly is difficult to understand, as it does not intoxicate like many vegetable poisons, nor produce fevers like contagious matter. When applied externally it seems chemically to destroy the part like other caustics. Does it chemically destroy the stomach, and life in consequence? or does it destroy the action of the stomach by its great stimulus, and life in consequence of the sympathy between the stomach and the heart? This last appears to be the most probable mode of its operation. The success of arsenic in the cure of intermittent fevers I suspect to depend on its stimulating the stomach into stronger action, and thus, by the association of this viscus with the heart and arteries, preventing the torpor of any part of the sanguiferous system. I was led to this conclusion from the following considerations. First. The effects of arsenic given a long time internally in small doses, or when used in larger quantities externally, seem to be similar to those of other great stimuli, as of wine or alcohol. These are a bloated countenance, swelled legs, hepatic tumours, and dropsy, and sometimes eruptions on the skin. The former of these I have seen, where arsenic has been used externally for curing the itch; and the latter appears on evidence in the famous trial of Miss Blandy at Chelmsford, about forty years ago. Secondly. I saw an ague cured by arsenic in a child, who had in vain previously taken a very large quantity of bark with great regularity. And another case of a young officer, who had lived intemperately, and laboured under an intermittent fever, and had taken the bark repeatedly in considerable quantities, with a grain of opium at night, and though the paroxysms had been thrice thus for a time prevented, they recurred in about a week. On taking five drops of a saturated solution of arsenic thrice a day the paroxysms ceased, and returned no more, and at the same time his appetite became much improved. Thirdly. A gentleman about 65 years of age had for about ten years been subject to an intermittent pulse, and to frequent palpitations of his heart. Lately the palpitations seemed to observe irregular periods, but the intermission of every third or fourth pulsation was almost perpetual. On giving him four drops of a saturated solution of arsenic from a two-ounce phial about every four hours for one day, not only the palpitation did not return, but the intermission ceased entirely, and did not return so long as he took the medicine, which was three or four days. Now as when the stomach has its action much weakened by an over-dose of digitalis, the pulse is liable to intermit, this evinces a direct sympathy between these parts of the system, and as I have repeatedly observed, that when the pulse begins to intermit in elderly people, that an eructation from the stomach, voluntarily produced, will prevent the threatened stop of the heart; I am induced to think, that the torpid state of the stomach, at the instant of the production of air occasioned by its weak action, caused the intermission of the pulse. And that arsenic in this case, as well as in the cases of agues above mentioned, produced its effects by stimulating the stomach into more powerful action; and that the equality of the motions of the heart was thus restored by increasing the excitement of the sensorial power of association. See Sect. XXV. 17. Class IV. 2. 1. 18. 10. Where arsenic has been given as a poison, it may be discovered in the contents of the stomach by the smell like garlic, when a few grains of it are thrown on a red-hot iron. 2. If a few grains are placed between two plates of copper, and subjected to a red heat, the copper becomes whitened. 3. Dissolve arsenic in water along with vegetable alcali, add to this a solution of blue vitriol in water, and the mixture becomes of a fine green, which gradually precipitates, as discovered by Bergman. 4. Where the quantity is sufficient, some wheat may be steeped in a solution of it, which given to sparrows or chickens will destroy them. VII. Absorption of the matter from venereal ulcers. No ulcer can heal, unless the absorption from it is as great as the deposition in it. The preparations or oxydes of mercury in the cure of the venereal disease seem to act by their increasing the absorption of the matter in the ulcers it occasions; and that whether they are taken into the stomach, or applied on the skin, or on the surface of the ulcers. And this in the same manner as sugar of lead, or other metallic oxydes, promote so rapidly the healing of other ulcers by their external application; and probably when taken internally, as rust of iron given to children affected with scrophulous ulcers contributes to heal them, and solutions of lead were once famous in phthisis. The matter deposited in large abscesses does not occasion hectic fever, till it has become oxygenated by being exposed to the open air, or to the air through a moist membrane; the same seems to happen to other kinds of matter, which produce fever, or which occasion spreading ulcers, and are thence termed contagious. See Class II. 1. 3. II. 1. 5. II. 1. 6. 6. This may perhaps occur from these matters not being generally absorbed, till they become oxygenated; and that it is the stimulus of the acid thus formed by their union with oxygen, which occasions their absorption into the circulation, and the fever, which they then produce. For though collections of matter, and milk, and mucus, are sometimes suddenly absorbed during the action of emetics or in sea-sickness, they are probably eliminated from the body without entering the circulation; that is, they are taken up by the increased action of one lymphatic branch, and evacuated by the inverted action of some other lymphatic branch, and thus carried off by stool or urine. But as the matter in large abscesses is in general not absorbed, till it becomes by some means exposed to air, there is reason to conclude, that the stimulus of this new combination of the matter with oxygen occasions its absorption; and that hence the absorption of matter in ulcers of all kinds, is still more powerfully effected by the external application or internal use of metallic oxydes; which are also acids consisting of the metal united with oxygen; and lastly, because venereal ulcers, and those of itch, and tinea, will not heal without some stimulant application; that is, the secretion of matter in them continues to be greater, than the absorption of it; and the ulcers at the same time continue to enlarge, by the contagion affecting the edges of them; that is, by the stimulus of the oxygenated matter stimulating the capillary vessels in its vicinity into actions similar to those of the ulcer, which produces it. This effect of the oxydes of mercury occurs, whether salivation attends its use or not. Salivation is much forwarded by external warmth, when mercury is given to promote this secretion; but as the cure of venereal complaints depends on its absorbent quality, the act of salivation is not necessary or useful. A quarter of a grain of good corrosive sublimate twice a day will seldom fail of curing the most confirmed pox; and will as seldom salivate, if the patient be kept cool. A quarter of a grain thrice a day I believe to be infallible, if it be good sublimate. Mercury alone when swallowed does not act beyond the intestines, its active preparations are the salts formed by its union with the various acids, as mentioned in the catalogue. Its union with the vegetable acid, when triturated with manna, is said to compose Keyser's Pill. Triturated with gum arabic it is much recommended by Plenk; and triturated with sugar and a little essential oil, as directed in a former Edinburgh Dispensatory, it probably forms some of the syrups sold as nostrums. United with sulphur it seldom enters the circulation, as when cinnabar, or Æthiop's mineral, are taken inwardly. But united with fat and rubbed on the skin, it is readily absorbed. I know not whether it can be united to charcoal, nor whether it has been given internally when united with animal fat. VIII. 1. Absorptions in general are increased by inanition; hence the use of evacuations in the cure of ulcers. Dr. Jurin absorbed in one night, after a day's abstinence and exercise, eighteen ounces from the atmosphere in his chamber; and every one must have observed, how soon his sheets became dry, after having been moistened by sweat, if he throws off part of the bed-clothes to cool himself; which is owing to the increased cutaneous absorption after the evacuation by previous sweat. 2. Now as opium is an universal stimulant, as explained in the article on Incitantia, it must stimulate into increased action both the secretory system, and the absorbent one; but after repeated evacuation by venesection, and cathartics, the absorbent system is already inclined to act more powerfully; as the blood-vessels being less distended, there is less resistance to the progress of the absorbed fluids into them. Hence after evacuations opium promotes absorption, if given in small doses, much more than it promotes secretion; and is thus eminently of service at the end of inflammations, as in pleurisy, or peripneumony, in the dose of four or five drops of the tincture, given before the access of the evening paroxysm; which I have seen succeed even when the risus sardonicus has existed. Some convulsions may originate in the want of the absorption of some acrid secretion, which occasions pain; hence these diseases are so much more certainly relieved by opium after venesection or other evacuations. IX. 1. Absorption is increased by the calces or solutions of mercury, lead, zinc, copper, iron, externally applied; and by arsenic, and by sulphur, and by the application of bitter vegetables in fine powder. Thus an ointment consisting of mercury and hog's fat rubbed on the skin cures venereal ulcers; and many kinds of herpetic eruptions are removed by an ointment consisting of 60 grains of white precipitate of mercury and an ounce of hog's fat. 2. The tumours about the necks of young people are often produced by the absorption of a saline or acrid material, which has been deposited from eruptions behind the ears, owing to deficient absorption in the surface of the ulcer, but which on running down on the skin below becomes absorbed, and swells the lymphatic glands of the neck; as the variolous matter, when inserted into the arm, swells the gland of the axilla. Sometimes the perspirative matter produced behind the ears becomes putrid from the want of daily washing them, and may also cause by its absorption the tumours of the lymphatics of the neck. In the former case the application of a cerate of lapis calaminaris, or of cerussa applied in dry powder, or of rags dipped in a solution of sugar of lead, increases the absorption in the ulcers, and prevents the effusion of the saline part of the secreted material. The latter is to be prevented by cleanliness. After the eruptions or ulcers are healed a solution of corrosive sublimate of one grain to an ounce of water applied for some weeks behind the ear, and amongst the roots of the hair on one side of the head, where the mouths of the lymphatics of the neck open themselves, frequently removes these tumours. 3. Linen rags moistened with a solution of half an ounce of sugar of lead to a pint of water applied on the erysipelas on anasarcous legs, which have a tendency to mortification, is more efficacious than other applications. White vitriol six grains dissolved in one ounce of rose-water removes inflammations of the eyes after evacuation more certainly than solutions of lead. Blue vitriol two or three grains dissolved in an ounce of water cures ulcers in the mouth, and other mucous membranes, and a solution of arsenic externally applied cures the itch, but requires great caution in the use of it. See Class II. 1. 5. 6. 4. Bitter vegetables, as the Peruvian bark, quilted between two shirts, or strewed in their beds, will cure the ague in children sometimes. Iron in solution, and some bitter extract, as in the form of ink, will cure one kind of herpes called the ringworm. And I have seen seven parts of bark in fine powder mixed with one part of ceruss, or white lead, in fine powder, applied dry to scrophulous ulcers, and renewed daily, with great advantage. 5. To these should be added electric sparks and shocks, which promote the absorption of the vessels in inflamed eyes of scrophulous children; and disperse, or bring to suppuration, scrophulous tumours about the neck. For this last purpose smart shocks should be passed through the tumours only, by inclosing them between two brass knobs communicating with the external and internal coating of a charged phial. See Art. II. 2. 2. 2. X. 1. Bandages increase absorption, if they are made to fit nicely on the part; for which purpose it is necessary to spread some moderately adhesive plaster on the bandage, and to cut it into tails, or into shreds two inches wide; the ends are to be wrapped over each other; and it must be applied when the part is least tumid, as in the morning before the patient rises, if on the lower extremities. The emplastrum de minio made to cover the whole of a swelled leg in this manner, whether the swelling is hard, which is usually termed scorbutic; or more easily compressible, as in anasarca, reduces the limb in two or three days to its natural size; for this purpose I have sometimes used carpenter's glue, mixed with one twentieth part of honey to prevent its becoming too hard, instead of a resinous plaster; but the minium plaster of the shops is in general to be preferred. Nothing so much facilitates the cure of ulcers in the legs, as covering the whole limb from the toes to the knee with such a plaster-bandage; which increases the power of absorption in the surface of the sore. 2. The lymph is carried along the absorbent vessels, which are replete with valves, by the intermitted pressure of the arteries in their neighbourhood. Now if the external skin of the limb be lax, it rises, and gives way to the pressure of the arteries at every pulsation; and thence the lymphatic vessels are subject to the pressure of but half the arterial force. But when the external skin is tightened by the surrounding bandage, and thence is not elevated by the arterial diastole, the whole of this power is exerted in compressing the lymphatic vessels, and carrying on the lymph already absorbed; and thence the absorbent power is so amazingly increased by bandage nicely applied. Pains are sometimes left in the fleshy parts of the thighs or arms, after the inflammation is gone, in the acute rheumatism, or after the patient is too weak for further evacuation; in this case after internal absorbent medicines, as the bark, and opiates, have been used in vain, I have successfully applied a plaster-bandage, as above described, so as to compress the pained part. XI. 1. We shall conclude by observing, that the sorbentia strengthen the whole habit by preventing the escape of the fluid part of the secretions out of the body, before it has given up as much nourishment, as it is capable; as the liquid part of the secretion of urine, sweat, saliva, and of all other secretions, which are poured into receptacles. Hence they have been said to brace the body, and been called tonics, which are mechanical terms not applicable to the living bodies of animals; as explained in Sect. XXXII. 3. 2. 2. A continued use of bitter medicines for years together, as of Portland's powder, or of the bark, is supposed to induce apoplexy, or other fatal diseases. Two cases of this kind have fallen under my observation; the patients were both rather intemperate in respect to the use of fermented liquors, and one of them had been previously subject to the gout. As I believe the gout generally originates from a torpor of the liver, which instead of being succeeded by an inflammation of it, is succeeded by an inflammation of some of the joints; or by a pimpled face, which is another mode, by which the disease of the liver is terminated. I conceive, that the daily use of bitter medicine had in these patients prevented the removal of a gouty inflammation from the liver to the membranes of the joints of the extremities, or to the skin of the face, by preventing the necessary torpor of these parts previous to the inflammation of them; in the same manner as cold fits of fever are prevented by the same medicines; and, as I believe, the returns of the gout have sometimes for two or three years been prevented by them. One of these patients died of the apoplexy in a few hours; and the other of an inflammation of the liver, which I believe was called the gout, and in consequence was not treated by venesection, and other evacuations. From hence it appears, that the daily use of hop in our malt liquor must add to the noxious quality of the spirit in it, when taken to excess, and contribute to the production of apoplexy, or inflammation of the liver. III. CATALOGUE OF THE SORBENTIA. I. Sorbentia affecting the skin. 1. Acid of vitriol, of sea-salt, lemons, sloes, prunus spinosa, crabs, pyrus, quince, pyrus cydonia, opium. 2. Externally calx of zinc, of lead, of mercury. II. Sorbentia affecting the mucous membranes. 1. Juice of sloes, crabs, Peruvian bark, cinchona, opium. 2. Externally blue vitriol. III. Sorbentia affecting the cellular membrane. 1. Peruvian bark, wormwoods, artemisia maritima, artemisia absynthium, worm-seed, artemisia santonicum, chamomile, anthemis nobilis, tansey tanacetum, bogbean, menyanthes trifoliata, centaury, gentiana centaurium, gentian, gentiana lutea, artichoke-leaves, cynara scolymus, hop, humulus lupulus. 2. Orange-peel, cinnamon, nutmeg, mace. 3. Vomits, squill, digitalis, tobacco. 4. Bath of warm air, of steam. IV. Sorbentia affecting the veins. 1. Water-cress, sisymbrium nasturtium aquaticum, mustard, sinapis, scurvy-grass cochlearia hortensis, horse-radish cochlearia armoracia, cuckoo-flower, cardamine, dog's-grass, dandelion, leontodon taraxacon, cellery apium, cabbage brassica. 2. Chalybeates, bitters, and opium, after sufficient evacuation. 3. Externally vinegar, friction, electricity. V. Sorbentia affecting the intestines. 1. Rhubarb, rheum palmatum, oak-galls, gallæ quercinæ, tormentil, tormentilla erecta, cinquefoil potentilla, red-roses, uva ursi, simarouba. 2. Logwood, hæmatoxylum campechianum, succus acaciæ, dragon's blood, terra japonica, mimosa catechu. 3. Alum, earth of alum, Armenian bole, chalk, creta, crab's claws, chelæ cancrorum, white clay, cimolia, calcined hartshorn, cornu cervi calcinatum, bone-ashes. VI. Sorbentia affecting the liver, stomach, and other viscera. Rust of iron, filings of iron, salt of steel, sal martis, blue vitriol, white vitriol, calomel, emetic tartar, sugar of lead, white arsenic. VII. Sorbentia affecting venereal ulcers. Mercury dissolved or corroded by the following acids: 1. Dissolved in vitriolic acid, called turpeth mineral, or hydrargyrus vitriolatus. 2. Dissolved in nitrous acid, called hydrargyrus nitratus ruber. 3. Dissolved in muriatic acid, mercurius corrosivus sublimatus, or hydrargyrus muriatus. 4. Corroded by muriatic acid. Calomel. 5. Precipitated from muriatic acid, mercurius precipitatus albus, calx hydrargyri alba. 6. Corroded by carbonic acid? The black powder on crude mercury. 7. Calcined, or united with oxygen. 8. United with animal fat, mercurial ointment. 9. United with sulphur. Cinnabar. 10. Partially united with sulphur. Æthiops mineral. 11. Divided by calcareous earth. Hydrargyrus cum cretâ. 12. Divided by vegetable mucilage, by sugar, by balsams. VIII. Sorbentia affecting the whole system. Evacuations by venesection and catharsis, and then by the exhibition of opium. IX. Sorbentia externally applied. 1. Solutions of mercury, lead, zinc, copper, iron, arsenic; or metallic calces applied in dry powder, as cerussa, lapis calaminaris. 2. Bitter vegetables in decoctions and in dry powders, applied externally, as Peruvian bark, oak bark, leaves of wormwood, of tansey, camomile flowers or leaves. 3. Electric sparks, or shocks. X. Bandage spread with emplastrum e minio, or with carpenter's glue mixed with one twentieth part of honey. XI. Portland's powder its continued use pernicious, and of hops in beer. * * * * * ART. V. INVERTENTIA. I. Those things, which invert the natural order of the successive irritative motions, are termed invertentia. 1. Emetics invert the motions of the stomach, duodenum, and oesophagus. 2. Violent cathartics invert the motions of the lacteals, and intestinal lymphatics. 3. Violent errhines invert the nasal lymphatics, and those of the frontal and maxillary sinuses. And medicines producing nausea, invert the motions of the lymphatics about the sauces. 4. Medicines producing much pale urine, as a certain quantity of alcohol, invert the motions of the urinary absorbents; if the dose of alcohol is greater, it inverts the stomach, producing the drunken sickness. 5. Medicines producing cold sweats, palpitation of the heart, globus hystericus; as violent evacuations, some poisons, fear, anxiety, act by inverting the natural order of the vascular motions. II. OBSERVATIONS ON THE INVERTENTIA. I. 1. The action of vomiting seems originally to have been occasioned by disagreeable sensation from the distention or acrimony of the aliment; in the same manner as when any disgustful material is taken into the mouth, as a bitter drug, and is rejected by the retrograde motions of the tongue and lips; as explained in Class IV. 1. 1. 2. and mentioned in Sect. XXXV. 1. 3. Or the disagreeable sensation may thus excite the power of volition, which may also contribute to the retrograde actions of the stomach and oesophagus, as when cows bring up the contents of their first stomach to re-masticate it. To either of these is to be attributed the action of mild emetics, which soon cease to operate, and leave the stomach stronger, or more irritable, after their operation; owing to the accumulation of the sensorial power of irritation during its torpid or inverted action. Such appears to be the operation of ipecacuanha, or of antimonium tartarizatum, in small doses. 2. But there is reason to believe, that the stronger emetics, as digitalis, first stimulate the absorbent vessels of the stomach into greater action; and that the inverted motions of these absorbents next occur, pouring the lymph, lately taken up, or obtained from other lymphatic branches, into the stomach: the quantity of which in some diseases, as in the cholera morbus, is inconceivable. This inverted motion, first of the absorbents of the stomach, and afterwards of the stomach itself, seems to originate from the exhaustion or debility, which succeeds the unnatural degree of action, into which they had been previously stimulated. An unusual defect of stimulus, as of food without spice or wine in the stomachs of those, who have been much accustomed to spice or wine, will induce sickness or vomiting; in this case the defective energy of the stomach is owing to defect of accustomed stimulus; while the action of vomiting from digitalis is owing to a deficiency of sensorial power, which is previously exhausted by the excess of its stimulus. See Sect. XXXV. 1. 3. and Class IV. 1. 1. 2. For first, no increase of heat arises from this action of vomiting; which always occurs, when the secerning system is stimulated into action. Secondly, the motions of the absorbent vessels are as liable to inversion as the stomach itself; which last, with the oesophagus, may be considered as the absorbent mouth and belly of that great gland, the intestinal canal. Thirdly, the class of sorbentia, as bitters and metallic salts, given in large doses, become invertentia, and vomit, or purge. And lastly, the sickness and vomiting induced by large potations of wine, or opium, does not occur till next day in some people, in none till some time after their ingurgitation. And tincture of digitalis in the dose of 30 or 60 drops, though applied in solution, is a considerable time before it produces its effect; though vomiting is instantaneously induced by a nauseous idea, or a nauseous taste in the mouth. At the same time there seem to be some materials, which can immediately stimulate the stomach into such powerful action, as to be immediately succeeded by paralysis of it, and consequent continued fever, or immediate death; and this without exciting sensation, that is, without our perceiving it. Of these are the contagious matter of some fevers swallowed with the saliva, and probably a few grains of arsenic taken in solution. See Suppl. I. 8. 8. Art. IV. 2. 6. 9. 3. Some branches of the lymphatic system become inverted by their sympathy with other branches, which are only stimulated into too violent absorption. Thus when the stomach and duodenum are much stimulated by alcohol, by nitre, or by worms, in some persons the urinary lymphatics have their motion inverted, and pour that material into the bladder, which is absorbed from the intestines. Hence the drunken diabetes is produced; and hence chyle is seen in the urine in worm cases. When on the contrary some branches of the absorbent systems have their motions inverted in consequence of the previous exhaustion of their sensorial power by any violent stimulus, other branches of it have their absorbent power greatly increased. Hence continued vomiting, or violent cathartics, produce great absorption from the cellular membrane in cases of dropsy; and the fluids thus absorbed are poured into the stomach and intestines by the inverted motions of the lacteals and lymphatics. See Sect. XXIX. 4. and 5. 4. The quantity of the dose of an emetic is not of so great consequence as of other medicines, as the greatest part of it is rejected with the first effort. All emetics are said to act with greater certainty when given in a morning, if an opiate had been given the night before. For the sensorial power of irritation of the stomach had thus been in some measure previously exhausted by the stimulus of the opium, which thus facilitates the action of the emetic; and which, when the dose of opium has been large, is frequently followed on the next day by spontaneous sickness and vomitings, as after violent intoxication. Ipecacuanha is the most certain in its effect from five grains to thirty; white vitriol is the most expeditious in its effect, from twenty grains to thirty dissolved in warm water; but emetic tartar, antimonium tartarizatum, from one grain to four to sane people, and from thence to twenty to insane patients, will answer most of the useful purposes of emetics; but nothing equals the digitalis purpurea for the purpose of absorbing water from the cellular membrane in the anasarca pulmonum, or hydrops pectoris. See Art. IV. 2. 3. 7. II. Violent cathartics. 1. Where violent cathartics are required, as in dropsies, the squill in dried powder made into small pills of a grain, or a grain and a half, one to be given every hour till they operate briskly, is very efficacious; or half a grain of emetic tartar dissolved in an ounce of peppermint-water, and given every hour, till it operates. Scammony, and other strong purges, are liable to produce hypercatharsis, if they are not nicely prepared, and accurately weighed, and are thence dangerous in common practice. Gamboge is uncertain in its effects, it has otherwise the good property of being tasteless; and on that account some preparation of it might be useful for children, by which its dose could be ascertained, and its effects rendered more uniform. 2. In inflammations of the bowels with constipation calomel, given in the dose from ten to twenty grains after due venesection, is most efficacious; and if made into very small pills is not liable to be rejected by vomiting, which generally attends those cases. When this fails, a grain of aloes every hour will find its way, if the bowel is not destroyed; and sometimes, I believe, if it be, when the mortification is not extensive. If the vomiting continues after the pain ceases, and especially if the bowels become tumid with air, which sounds on being struck with the finger, these patients seldom recover. Opiates given along with the cathartics I believe to be frequently injurious in inflammation of the bowels, though they may thus be given with advantage in the saturnine colic; the pain and constipation in which disease are owing to torpor or inactivity, and not to too great action. III. Violent errhines and sialagogues. 1. Turpeth mineral in the quantity of one grain mixed with ten grains of sugar answers every purpose to be expected from errhines. Their operation is by inverting the motions of the lymphatics of the membrane, which lines the nostrils, and the caverns of the forehead and cheeks; and may thence possibly be of service in the hydrocephalus internus. Some other violent errhines, as the powder of white hellebore, or Cayan pepper, diluted with some less acrid powder, are said to cure some cold or nervous head-achs; which may be effected by inflaming the nostrils, and thus introducing the sensorial power of sensation, as well as increasing that of irritation; and thus to produce violent action of the membranes of the nostrils, and of the frontal and maxillary sinuses, which may by association excite into action the torpid membranes, which occasion the head-ach. 2. A copious salivation without any increase of heat often attends hysteric diseases, and fevers with debility, owing to an inversion of the lymphatics of the mouth, see Class I. 1. 2. 6. The same occurs in the nausea, which precedes vomiting; and is also excitable by disagreeable tastes, as by squills, or by nauseous smells, or by nauseous ideas. These are very similar to the occasional discharge of a thin fluid from the nostrils of some people, which recurs at certain periods, and differs from defective absorption. IV. Violent diuretics. 1. If nitre be given from a dram to half an ounce in a morning at repeated draughts, the patient becomes sickish, and much pale water is thrown into the bladder by the inverted action of the urinary lymphatics. Hence the absorption in ulcers is increased and the cure forwarded, as observed by Dr. Rowley. 2. Cantharides taken inwardly so stimulate the neck of the bladder as to increase the discharge of mucus, which appears in the urine; but I once saw a large dose taken by mistake, not less than half an ounce or an ounce of the tincture, by which I suppose the urinary lymphatics were thrown into violent inverted motions, for the patient drank repeated draughts of subtepid water to the quantity of a gallon or two in a few hours; and during the greatest part of that time he was not I believe two entire minutes together without making water. A little blood was seen in his water the next day, and a soreness continued a day longer without any other inconvenience. 3. The decoction of foxglove should also be mentioned here, as great effusions of urine frequently follow its exhibition. See Art. IV. 2. 3. 7. And an infusion or tincture of tobacco as recommended by Dr. Fowler of York. 4. Alcohol, and opium, if taken so as to induce slight intoxication, and the body be kept cool, and much diluting liquids taken along with them, have similar effect in producing for a time a greater flow of urine, as most intemperate drinkers must occasionally have observed. This circumstance seems to have introduced the use of gin, and other vinous spirits as a diuretic, unfortunately in the gravel, amongst ignorant people; which disease is generally produced by fermented or spirituous liquors, and always increased by them. 5. Fear and anxiety are well known to produce a great frequency of making water. A person, who believed he had made a bad purchase concerning an estate, told me, that he made five or six pints of water during a sleepless night, which succeeded his bargain; and it is usual, where young men are waiting in an anti-room to be examined for college preferment, to see the chamber-pot often wanted. V. Cold sweats about the head, neck, and arms, frequently attend those, whose lungs are oppressed, as in some dropsies and asthma. A cold sweat is also frequently the harbinger of death. These are from the inverted motions of the cutaneous lymphatic branches of those parts. III. CATALOGUE OF INVERTENTIA. I. Emetics, ipecacuanha, emetic tartar, antimonium tartarisatum, squill, scilla maritima, carduus benedictus, cnicus acarna, chamoemile, anthemis nobilis, white vitriol, vitriolum zinci, foxglove, digitalis purpurea, clysters of tobacco. II. Violent cathartics, emetic tartar, squill, buckthorn, rhamnus catharticus, scammonium, convolvulus scammonia, gamboge, elaterium, colocynth, cucumis colocynthis, veratrum. III. Violent errhines and sialagogues, Turpeth mineral, hydrargyrus vitriolatus, asarum europæum, euphorbium, capsicum, veratrum, nauseous smells, nauseous ideas. IV. Violent diuretics, nitre, squill, seneka, cantharides, alcohol, foxglove, tobacco, anxiety. V. Cold sudorifics, poisons, fear, approaching death. * * * * * ART. VI. REVERTENTIA. I. Those things, which restore the natural order of the inverted irritative motions, are termed Revertentia. 1. As musk, castor, asafoetida, valerian, essential oils. 2. Externally the vapour of burnt feathers, of volatile salts, or oils, blisters, sinapisms. These reclaim the inverted motions without increasing the heat of the body above its natural state, if given in their proper doses, as in the globus hystericus, and palpitation of the heart. The incitantia revert these morbid motions more certainly, as opium and alcohol; and restore the natural heat more; but if they induce any degree of intoxication, they are succeeded by debility, when their stimulus ceases. II. OBSERVATIONS ON THE REVERTENTIA. I. The hysteric disease is attended with inverted motions feebly exerted of the oesophagus, intestinal canal and lymphatics of the bladder. Hence the borborigmi, or rumbling of the bowels, owing to their fluid contents descending as the air beneath ascends. The globus hystericus consists in the retrograde motion of the oesophagus, and the great flow of urine from that of the lymphatics spread on the neck of the bladder; and a copious salivation sometimes happens to these patients from the inversion of the lymphatics of the mouth; and palpitation of the heart owing to weak or incipient inversion of its motions; and syncope, when this occurs in its greatest degree. These hysteric affections are not necessarily attended with pain; though it sometimes happens, that pains, which originate from quiescence, afflict these patients, as the hemicrania, which has erroneously been termed the clavus hystericus; but which is owing solely to the inaction of the membranes of that part, like the pains attending the cold fits of intermittents, and which frequently returns like them at very regular periods of time. Many of the above symptoms are relieved by musk, castor, the foetid gums, valerian, oleum animale, oil of amber, which act in the usual dose without heating the body. The pains, which sometimes attend these constitutions, are relieved by the secernentia, as essential oils in common tooth-ach, and balsam of Peru in the flatulent colic. But the incitantia, as opium, or vinous spirit, reclaim these morbid inverted motions with more certainty, than the foetids; and remove the pains, which attend these constitutions, with more certainty than the secernentia; but if given in large doses, a debility and return of the hysteric symptoms occurs, when the effect of the opium or alcohol ceases. Opiates and foetids joined seem best to answer the purpose of alleviating the present symptoms; and the sorbentia, by stimulating the lymphatics and lacteals into continued action, prevent a relapse of their inversion, as Peruvian bark, and rust of iron. See Class I. 3. 1. 10. II. Vomiting consists in the inverted order of the motions of the stomach, and oesophagus; and is also attended with the inverted motions of a part of the duodenum, when bile is ejected; and of the lymphatics of the stomach and fauces, when nausea attends, and when much lymph is evacuated. Permanent vomiting is for a time relieved by the incitantia, as opium or alcohol; but is liable to return, when their action ceases. A blister on the back, or on the stomach, is more efficacious for restraining vomiting by their stimulating into action the external skin, and by sympathy affecting the membranes of the stomach. In some fevers attended with incessant vomiting Sydenham advised the patient to put his head under the bed-clothes, till a sweat appeared on the skin, as explained in Class IV. 1. 1. 2. In chronical vomiting I have observed crude mercury of good effect in the dose of half an ounce twice a day. The vomitings, or vain efforts to vomit, which sometimes attend hysteric or epileptic patients, are frequently instantly relieved for a time by applying flour of mustard-seed and water to the small of the leg; and removing it, as soon as the pain becomes considerable. If sinapisms lie on too long, especially in paralytic cases, they are liable to produce troublesome ulcers. A plaster or cataplasm, with opium and camphor on the region of the stomach, will sometimes revert its retrograde motions. III. Violent catharsis, as in diarrhoea or dysentery, is attended with inverted motions of the lymphatics of the intestines, and is generally owing to some stimulating material. This is counteracted by plenty of mucilaginous liquids, as solutions of gum arabic, or small chicken broth, to wash away or dilute the stimulating material, which causes the disease. And then by the use of the intestinal sorbentia, Art. IV. 2. 5. as rhubarb, decoction of logwood, calcined hartshorn, Armenian bole; and lastly, by the incitantia, as opium. IV. The diabætes consists in the inverted motions of the urinary lymphatics, which is generally I suppose owing to the too great action of some other branch of the absorbent system. The urinary branch should be stimulated by cantharides, turpentine, resin (which when taken in larger doses may possibly excite it into inverted action), by the sorbentia and opium. The intestinal lymphatics should be rendered less active by torpentia, as calcareous earth, earth of alum; and those of the skin by oil externally applied over the whole body; and by the warm-bath, which should be of 96 or 98 degrees of heat, and the patient should sit in it every day for half an hour. V. Inverted motions of the intestinal canal with all the lymphatics, which open into it, constitute the ileus, or iliac passion; in which disease it sometimes happens, that clysters are returned by the mouth. After venesection from ten grains to twenty of calomel made into very small pills; if this is rejected, a grain of aloe every hour; a blister; crude mercury; warm-bath; if a clyster of iced water? Many other inverted motions of different parts of the system are described in Class I. 3. and which are to be treated in a manner similar to those above described. It must be noted, that the medicines mentioned under number one in the catalogue of revertentia are the true articles belonging to this class of medicines. Those enumerated in the other four divisions are chiefly such things as tend to remove the stimulating causes, which have induced the inversion of the motions of the part, as acrimonious contents, or inflammation, of the bowels in diarrhoea, diabetes, or in ileus. But it is probable after these remote causes are destroyed, that the fetid gums, musk, castor, and balsams, might be given with advantage in all these cases. III. CATALOGUE OF REVERTENTIA. I. Inverted motions, which attend the hysteric disease, are reclaimed, 1. By musk, castor. 2. By asafoetida, galbanum, sagapænum, ammoniacum, valerian. 3. Essential oils of cinnamon, nutmeg, cloves, infusion of penny-royal, mentha, pulegium, peppermint, mentha piperita, ether, camphor. 4. Spirit of hartshorn, oleum animale, spunge burnt to charcoal, black-snuffs of candles, which consist principally of animal charcoal, wood-soot, oil of amber. 5. The incitantia, as opium, alcohol, vinegar. 6. Externally the smoke of burnt feathers, oil of amber, volatile salt applied to the nostrils, blisters, sinapisms. II. Inverted motions of the stomach are reclaimed by opium, alcohol, blisters, crude mercury, sinapisms, camphor and opium externally, clysters with asafoetida. III. Inverted motions of the intestinal lymphatics are reclaimed by mucilaginous diluents, and by intestinal sorbentia, as rhubarb, logwood, calcined hartshorn, Armenian bole; and lastly by incitantia, as opium. IV. Inverted motions of the urinary lymphatics are reclaimed by cantharides, turpentine, rosin, the sorbentia, and opium, with calcareous earth, and earth of alum, by oil externally, warm-bath. V. Inverted motions of the intestinal canal are reclaimed by calomel, aloe, crude mercury, blisters, warm-bath, clysters with asafoetida, clysters of iced water? or of spring water further cooled by salt dissolved in water contained in an exterior vessel? Where there exists an introsusception of the bowel in children, could the patient be held up for a time by the feet with his head downwards, or be laid with his body on an inclined plane with his head downwards, and crude mercury be injected as a clyster to the quantity of two or three pounds? * * * * * ART. VII. TORPENTIA. I. Those things, which diminish the exertion of the irritative motions, are termed torpentia. 1. As mucus, mucilage, water, bland oils, and whatever possesses less stimulus than our usual food. Diminution of heat, light, sound, oxygen, and of all other stimuli; venesection, nausea, and anxiety. 2. Those things which chemically destroy acrimony, as calcareous earth, soap, tin, alcalies, in cardialgia; or which prevent chemical acrimony, as acid of vitriol in cardialgia, which prevents the fermentation of the aliment in the stomach, and its consequent acidity. Secondly, which destroy worms, as calomel, iron filings or rust of iron, in the round worms; or amalgama of quicksilver and tin, or tin in very large doses, in the tape-worms. Will ether in clysters destroy ascarides? Thirdly, by chemically destroying extraneous bodies, as caustic alcali, lime, mild alcali in the stone. Fourthly, those things which lubricate the vessels, along which extraneous bodies slide, as oil in the stone in the urethra, and to expedite the expectoration of hardened mucus; or which lessen the friction of the contents in the intestinal canal in dysentery or aphtha, as calcined hartshorn, clay, Armenian bole, chalk, bone-ashes. Fifthly, such things as soften or extend the cuticle over tumors, or phlegmons, as warm water, poultices, fomentations, or by confining the perspirable matter on the part by cabbage-leaves, oil, fat, bee's-wax, plasters, oiled silk, externally applied. These decrease the natural heat and remove pains occasioned by excess of irritative motions. II. OBSERVATIONS ON THE TORPENTIA. I. As the torpentia consist of such materials as are less stimulating than our usual diet, it is evident, that where this class of medicines is used, some regard must be had to the usual manner of living of the patient both in respect to quantity and quality. Hence wounds in those, who have been accustomed to the use of much wine, are very liable to mortify, unless the usual potation of wine be allowed the patient. And in these habits I have seen a delirium in a fever cured almost immediately by wine; which was occasioned by the too mild regimen directed by the attendants. On the contrary in great inflammation, the subduction of food, and of spirituous drink, contributes much to the cure of the disease. As by these means both the stimulus from distention of the vessels, as well as that from the acrimony of the fluids, is decreased; but in both these respects the previous habits of diet of the patients must be attended to. Thus if tea be made stronger, than the patient has usually drank it, it belongs to the article sorbentia; if weaker, it belongs to the torpentia. II. Water in a quantity greater than usual diminishes the action of the system not only by diluting our fluids, and thence lessening their stimulus, but by lubricating the solids; for not only the parts of our solids have their sliding over each other facilitated by the interposition of aqueous particles; but the particles of mucaginous or saccharine solutions slide easier over each other by being mixed with a greater portion of water, and thence stimulate the vessels less. At the same time it must be observed, that the particles of water themselves, and of animal gluten dissolved in water, as the glue used by carpenters, slide easier over each other by an additional quantity of the fluid matter of heat. These two fluids of heat and of water may be esteemed the universal solvents or lubricants in respect to animal bodies, and thus facilitate the circulation, and the secretion of the various glands. At the same time it is possible, that these two fluids may occasionally assume an aerial form, as in the cavity of the chest, and by compressing the lungs may cause one kind of asthma, which is relieved by breathing colder air. An increased quantity of heat by adding stimulus to every part of the system belongs to the article Incitantia. III. 1. The application of cold to the skin, which is only another expression for the diminution of the degree of heat we are accustomed to, benumbs the cutaneous absorbents into inaction; and by sympathy the urinary and intestinal absorbents become also quiescent. The secerning vessels continuing their action somewhat longer, from the warmth of the blood. Hence the usual secretions are poured into the bladder and intestines, and no absorption is retaken from them. Hence sprinkling the skin with cold water increases the quantity of urine, which is pale; and of stool, which is fluid; these have erroneously been ascribed to increased secretion, or to obstructed perspiration. The thin discharge from the nostrils of some people in cold weather is owing to the torpid state of the absorbent vessels of the membrana sneideriana, which as above are benumbed sooner than those, which perform the secretion of the mucus. The quick anhelation, and palpitation of the heart, of those, who are immersed in cold water, depends on the quiescence of the external absorbent vessels and capillaries. Hence the cutaneous circulation is diminished, and by association an almost universal torpor of the system is induced; thence the heart becomes incapable to push forwards its blood through all the inactive capillaries and glands; and as the terminating vessels of the pulmonary artery suffer a similar inaction by association, the blood is with difficulty pushed through the lungs. Some have imagined, that a spasmodic constriction of the smaller vessels took place, and have thus accounted for their resistance to the force of the heart. But there seems no necessity to introduce this imaginary spasm; since those, who are conversant in injecting bodies, find it necessary first to put them into warm water to take away the stiffness of the cold dead vessels; which become inflexible like the other muscles of dead animals, and prevent the injected fluid from passing. All the same symptoms occur in the cold fits of intermittents; in these the coldness and paleness of the skin with thirst evince the diminution of cutaneous absorption; and the dryness of ulcers, and small secretion of urine, evince the torpor of the secerning system; and the anhelation, and coldness of the breath, shew the terminations of the pulmonary artery to be likewise affected with torpor. After these vessels of the whole surface of the body both absorbent and secretory have been for a time torpid by the application of cold water; and all the internal secerning and absorbent ones have been made torpid from their association with the external; as soon as their usual stimulus of warmth is renewed, they are thrown into more than their usual energy of action; as the hands become hot and painful on approaching the fire after having been immersed some time in snow. Hence the face becomes of a red colour in a cold day on turning from the wind, and the insensible perspiration increased by repeatedly going into frosty air, but not continuing in it too long at a time. 2. When by the too great warmth of a room or of clothes, the secretion of perspirable matter is much increased, the strength of the patient is much exhausted by this unnecessary exertion of the capillary system, and thence of the whole secerning and arterial system by association. The diminution of external heat immediately induces a torpor or quiescence of these unnecessary exertions, and the patient instantly feels himself strengthened, and exhilarated; the animal power, which was thus wasted in vain, being now applied to more useful purposes. Thus when the limbs on one side are disabled by a stroke of the palsy, those of the other side are perpetually in motion. And hence all people bear riding and other exercises best in cold weather. Patients in fevers, where the skin is hot, are immediately strengthened by cold air; which is therefore of great use in fevers attended with debility and heat; but may perhaps be of temporary disservice, if too hastily applied in some situations of fevers attended with internal topical inflammation, as in peripneumony or pleurisy, where the arterial strength is too great already, and the increased action of the external capillaries being destroyed by the cold, the action of the internal inflamed part may be suddenly increased, unless venesection and other evacuations are applied at the same time. Yet in most cases the application of cold is nevertheless salutary, as by decreasing the heat of the particles of blood in the cutaneous vessels, the stimulus of them, and the distention of the vessels becomes considerably lessened. In external inflammations, as the small-pox, and perhaps the gout and rheumatism, the application of cold air must be of great service by decreasing the action of the inflamed skin, though the contrary is too frequently the practice in those diseases. It must be observed, that for all these purposes the application of it should be continued a long time, otherwise an increased exertion follows the temporary torpor, before the disease is destroyed. 3. After immersion in cold water or in cold air the whole system becomes more exciteable by the natural degree of stimulus, as appears from the subsequent glow on the skin of people otherwise pale; and even by a degree of stimulus less than natural, as appears by their becoming warm in a short time during their continuance in a bath, of about 80 degrees of heat, as in Buxton bath. See Sect XII. 2. 1. XXXII. 3. 3. This increased exertion happens to the absorbent vessels more particularly, as they are first and most affected by these temporary diminutions of heat; and hence like the medicines, which promote absorption, the cold-bath contributes to strengthen the constitution, that is to increase its irritability; for the diseases attended with weakness, as nervous fevers and hysteric diseases, are shewn in Section XXXII. 2. 1. to proceed from a want of irritability, not from an excess of it. Hence the digestion is greater in frosty weather, and the quantity of perspiration. For these purposes the application of cold must not be continued too long. For in riding a journey in cold weather, when the feet are long kept too cold, the digestion is impaired, and cardialgia produced. 4. If the diminution of external heat be too great, produced too hastily, or continued too long, the torpor of the system either becomes so great, that the animal ceases to live; or so great an energy of motion or orgasm of the vessels succeeds, as to produce fever or inflammation. This most frequently happens after the body has been temporarily heated by exercise, warm rooms, anger, or intemperance. Hence colds are produced in the external air by resting after exercise, or by drinking cold water. See Class I. 2. 2. 1. Frequent cold immersions harden or invigorate the constitution, which they effect by habituating the body to bear a diminution of heat on its surface without being thrown into such extensive torpor or quiescence by the consent of the vessels of the skin with the pulmonary and glandular system; as those experience, who frequently use the cold-bath. At first they have great anhelation and palpitation of heart at their ingress into cold water; but by the habit of a few weeks they are able to bear this diminution of heat with little or no inconvenience; for the power of volition has some influence over the muscles subservient to respiration, and by its counter efforts gradually prevents the quick breathing, and diminishes the associations of the pulmonary vessels with the cutaneous ones. And thus though the same quantity of heat is subducted from the skin, yet the torpor of the pulmonary vessels and internal glands does not follow. Hence during cold immersion less sensorial power is accumulated, and in consequence, less exertion of it succeeds on emerging from the bath. Whence such people are esteemed hardy, and bear the common variations of atmospheric temperature without inconvenience. See Sect. XXXII. 3. 2. IV. Venesection has a just title to be classed amongst the torpentia in cases of fever with arterial strength, known by the fulness and hardness of the pulse. In these cases the heat becomes less by its use, and all exuberant secretions, as of bile or sweat, are diminished, and room is made in the blood-vessels for the absorption of mild fluids; and hence the absorption also of new vessels, or extravasated fluids, the produce of inflammation, is promoted. Hence venesection is properly classed amongst the sorbentia, as like other evacuations it promotes general absorption, restrains hæmorrhages, and cures those pains, which originate from the too great action of the secerning vessels, or from the torpor of the absorbents. I have more than once been witness to the sudden removal of nervous head-achs by venesection, though the patient was already exhausted, pale, and feeble; and to its great use in convulsions and madness, whether the patient was strong or weak; which diseases are the consequence of nervous pains; and to its stopping long debilitating hæmorrhages from the uterus, when other means had been in vain essayed. In inflammatory pains, and inflammatory hæmorrhages, every one justly applies to it, as the certain and only cure. V. When the circulation is carried on too violently, as in inflammatory fevers, those medicines, which invert the motions of some parts of the system, retard the motions of some other parts, which are associated with them. Hence small doses of emetic tartar, and ipecacuanha, and large doses of nitre, by producing nausea debilitate and lessen the energy of the circulation, and are thence useful in inflammatory diseases. It must be added, that if nitre be swallowed in powder, or soon after it is dissolved, it contributes to lessen the circulation by the cold it generates, like ice-water, or the external application of cold air. VI. The respiration of air mixed with a greater proportion of azote than is found in the common atmosphere, or of air mixed with hydrogen, or with carbonic acid gas, so that the quantity of oxygen might be less than usual, would probably act in cases of inflammation with great advantage. In consumptions this might be most conveniently and effectually applied, if a phthisical patient could reside day and night in a porter or ale brewery, where great quantities of those liquors were perpetually fermenting in vats or open barrels; or in some great manufactory of wines from raisins or from sugar. Externally the application of carbonic acid gas to cancers and other ulcers instead of atmospheric air may prevent their enlargement, by preventing the union of oxygen with matter, and thus producing a new contagious animal acid. III. CATALOGUE OF TORPENTIA. 1. Venesection. Arteriotomy. 2. Cold water, cold air, respiration of air with less oxygen. 3. Vegetable mucilages. a. Seeds.--Barley, oats, rice, young peas, flax, cucumber, melon, &c. b. Gums.--Arabic, Tragacanth, Senegal, of cherry-trees. c. Roots.--Turnip, potatoe, althea, orchis, snow-drop. d. Herbs.--Spinach, brocoli, mercury. 4. Vegetable acids, lemon, orange, currants, gooseberries, apples, grape, &c. &c. 5. Animal mucus, hartshorn jelly, veal broth, chicken water, oil? fat? cream? 6. Mineral acids, of vitriol, nitre, sea-salt. 7. Silence, darkness. 8. Invertentia in small doses, nitre, emetic tartar, ipecacuanha given so as to induce nausea. 9. Antacids.--Soap, tin, alcalies, earths. 10. Medicines preventative of fermentation, acid of vitriol. 11. Anthelmintics.--Indian pink, tin, iron, cowhage, amalgama, smoak of tobacco. 12. Lithonthriptics, lixiv. saponarium, aqua calcis, fixable air. 13. Externally, warm bath, and poultices, oil, fat, wax, plasters, oiled silk, carbonic acid gas on cancers, and other ulcers. * * * * * ADDENDA. _Page 625, line 1, after 'number' please to add_, 'except when the patient has naturally a pulse slower than usual in his healthy state.' _Page 197, after line 8, please to add_, 'Where the difficulty of breathing is very urgent in the croup, bronchotomy is recommended by Mr. Field.' Memoir of a Medical Society, London, 1773, Vol. IV. * * * * * ADDITION. * * * * * INABILITY TO EMPTY THE BLADDER. To be introduced at the end of Class III. 2. 1. 6. on Paralysis Vesicæ Urinariæ. An inability to empty the bladder frequently occurs to elderly men, and is often fatal. This sometimes arises from their having too long been restrained from making water from accidental confinement in public society, or otherwise; whence the bladder has become so far distended as to become paralytic; and not only this, but the neck of the bladder has become contracted so as to resist the introduction of the catheter. In this deplorable case it has frequently happened, that the forcible efforts to introduce the catheter have perforated the urethra; and the instrument has been supposed to pass into the bladder when it has only passed into the cellular membrane along the side of it; of which I believe I have seen two or three instances; and afterwards the part has become so much inflamed as to render the introduction of the catheter into the bladder impracticable. In this situation the patients are in imminent danger, and some have advised a trocar to be introduced into the bladder from the rectum; which I believe is generally followed by an incurable ulcer. One patient, whom I saw in this situation, began to make a spoonful of water after six or seven days, and gradually in a few days emptied his bladder to about half its size, and recovered; but I believe he never afterwards was able completely to evacuate it. In this situation I lately advised about two pounds of crude quicksilver to be poured down a glass tube, which was part of a barometer tube, drawn less at one end, and about two feet long, into the urethra, as the patient lay on his back; which I had previously performed upon a horse; this easily passed, as was supposed, into the bladder; on standing erect it did not return, but on kneeling down, and lying horizontally on his hands, the mercury readily returned; and on this account it was believed to have passed into the bladder, as it so easily returned, when the neck of the bladder was lower than the fundus of it. But nevertheless as no urine followed the mercury, though the bladder was violently distended, I was led to believe, that the urethra had been perforated by the previous efforts to introduce a catheter and bougee; and that the mercury had passed on the outside of the bladder into the cellular membrane. As the urethra is so liable to be perforated by the forcible efforts to introduce the catheter, when the bladder is violently distended in this deplorable disease, I should strongly recommend the injection of a pound or two of crude mercury into the urethra to open by its weight the neck of the bladder previous to any violent or very frequent essays with a catheter whether of metal or of elastic resin. * * * * * LINES TO BE PLACED AT THE END OF ZOONOMIA. _BY A FRIEND._ * * * * * _JAMQUE OPUS EXEGI._ * * * * * The work is done!--nor Folly's active rage, Nor Envy's self, shall blot the golden page; Time shall admire, his mellowing touch employ, And mend the immortal tablet, not destroy. * * * * * INDEX OF THE ARTICLES. A. Absorption, iv. 2. 1. ---- cutaneous, mucous, cellular, iv. 2. 2. ---- of the veins, iv. 2. 4. ---- of inflamed vessels, iv. 2. 4. 3. ---- of intestines and liver, iv. 2. 5. ---- of venereal ulcers, iv. 2. 7. ---- not increased by cold, iv. 2. 1. ---- increased by opium after evacuation, ii. 2. 1. Acacia, iv. 3. 5. 2. Acids austere, iv. 2. 1. 2. iv. 3. 1. ---- vegetable, sweet, vii. 3. 4. iv. 2. 1. 2. ---- mineral, vii. 3. 6. Acrid plants, iv. 2. 4. Agriculture, i. 2. 3. 7. Agues, three kinds, iv. 2. 3. 2. iv. 2. 5. iv. 2. 6. 8. Air nourishes, i. 2. 5. ---- warm bath of, iv. 2. 3. 8. Alcali vol. iii. 3. 8. Alcohol, ii. 2. 1. v. 2. 4. Almond, bitter, ii. 3. 1. Althæa, iii. 3. 3. 3. Allium, iii. 3. 3. Aloe, iii. 2. 5. iii. 2. 7. iii. 3. 5. 5. vi. 2. 5. Alum, iii. 2. 1. iv. 2. 2. iv. 2. 5. 2. iv. 2. 5. 3. Amalgama in worms, vii. 1. 2. Amomum zinziber, iii. 3. 1. Amber, oil of, vi. 3. 1. 4. Ammoniac gum, vi. 3. 1. iii. 3. 3. ---- salt or spirit, iii. 3. 1. 3. Anasarca, warm bath in, ii. 2. 2. Anchovy, iii. 2. 1. iii. 3. 1. 4. Animal food, i. 2. 1. 1. Antimony prepared, iii. 3. 1. 5. iii. 2. 1. iv. 1. 10. Anthemis nobilis, iv. 3. 3. ---- pyrethum, iii. 3. 2. Anxiety, v. 2. 4. Apium, petroselinum, iii. 3. 4. 4. Apoplexy, iv. 2. 11. Aristolochia serpentaria, iii. 3. 1. Armenian bole, vi. 2. 3. iv. 3. 5. 3. Arsenic in ague, iv. 2. 6. 8. iv. 3. 6. ---- saturated solution of, iv. 2. 6. 8. ---- in itch, iv. 2. 9. ---- how it acts, iv. 2. 6. 9. ---- how to detect it, iv. 2. 6. 10. Artemisia maritima, iv. 3. 3. ---- absynthium, iv. 3. 3. ---- santonicum, iv. 3. 3. Artichoke-leaves, iv. 3. 3. Asa foetida, iii. 3. vi. 3. 1. Asarum Europeum v. 3. 3. Ascarides, vii. 1. 2. iii. 2. 7. Asparagus, iii. 3. 4. 4. Astragalus tragacanth, iii. 3. 3. 3. Atropa belladona, ii. 3. 1. Azote, i. 2. 5. B. Balsams diuretic, iii. 2. 4. Bandages promote absorption, iv. 2. 10. Bark, Peruvian, iv. 2. 2. ---- long used noxious, iv. 2. 11. Barley, iii. 3. 3. 3. Bath, warm, ii. 2. 2. 1. iii. 3. 1. 6. iii. 3. 3. 4. iii. 2. 3. 3. ---- of warm air, iv. 2. 3. 8. ---- of steam, iv. 2. 3. 8. ---- cold, vii. 2. 3. ---- nutritive, i. 2. 6. 1. Benzoin, iii. 3. 3. Bile of animals, iii. 3. 5. 2. ---- dilute state of, iv. 2. 6. Blisters, how they act, iii. 2. 1. 10. ---- cure heart-burn, iii. 2. 1. 10. ---- stop vomiting, vi. 2. 2. ---- produce expectoration, iii. 2. 3. 2. ---- increase perspiration, iii. 2. 1. 10. Blood, transfusion of, i. 2. 6. 3. Bog-bean, iv. 3. 3. Bole armeniæ, iv. 2. 5. 3. Bone-ashes, iv. 2. 5. 3. Bowels, inflammation of, v. 2. 2. 2. Bryony, white, iii. 3. 8. ---- as a blister, iii. 2. 8. Butter, i. 2. 3. 2. Butter-milk, i. 2. 2. 2. C. Cabbage-leaves, vii. 1. 2. Calcareous earth, i. 2. 4. 3. Calomel, iii. 2. 5. vi. 2. 5. ---- in enteritis, v. 2. 2. 2. Camphor, iii. 3. 1. Canella alba, iii. 3. 1. Cantharides, iii. 2. 6. iii. 2. 8. v. 2. 4. vi. 2. 4. Capillary action increased by tobacco, iv. 2. 3. 7. Capsicum, iii. 3. 1. Carbonic acid gas, vii. 2. 6. Cardamomum, iii. 3. 1. Caryophyllus aromat. iii. 3. 1. Cardamine, iv. 3. 4. Cassia sistul, iii. 3. 5. 1. ---- senna, iii. 3. 5. 5. Castor, vi. 2. 1. vi. 3. 1. Cathartics, mild, iii. 2. 5. ---- violent, v. 2. 2. Cerussa in ulcers, iv. 2. 9. iv. 2. 7. Chalk, iv. 2. 5. 3. Chalybeates, iv. 3. 4. 2. Cheese, i. 2. 2. 3. Cherries, black, ii. 2. 1. 8. Chlorosis, iv. 2. 6. 5. Cicuta, ii. 3. 1. Cinchona, iv. 2. 2. Cinnamon, iii. 3. 1. 2. Clay, iv. 2. 5. 3. Cloves, iii. 3. 1. iii. 3. 2. Cnicus acarna, v. 3. 1. Cocculus indicus, ii. 3. 1. Cochlearia armoracia, iii. 3. 8. iv. 3. 4. ---- hortensis, iv. 3. 4. Cold, continued application of, vii. 2. 3. ---- interrupted, vii. 2. 3. iii. 3. 1. 7. ---- excessive, vii. 2. 3. ---- first affects lymphatics, vii. 2. 3. ---- produces rheum from the nose, vii. 2. 3. ---- quick anhelation, vii. 2. 3. ---- increases digestion, vii. 2. 3. Cold-fit easier prevented than removed, ii. 2. 1. Colic from lead, v. 2. 2. 2. Condiments, i. 2. 7. Convolvulus scammonium, v. 3. 2. Convulsions, iv. 2. 8. Cookery, i. 2. 3. 5. Copaiva balsam, iii. 3. 4. 3. Cowhage, iii. 3. 2. Crab-juice, iv. 2. 2. Cream, i. 2. 3. 2. i. 2. 2. 2. Cucumis colocynthis, v. 3. 2. Cynara scolymus, iv. 3. 3. Cynoglossum, ii. 3. 1. D. Dandelion, iv. 3. 4. Datura stramonium, ii. 3. 1. Daucus sylvestris, iii. 3. 4. 4. Delphinium stavisagria, ii. 3. 1. Diabetes, iv. 2. 5. ---- warm bath in, vi. 2. 4. Diaphoretics, iii. 3. 1. iii. 2. 1. 2. ---- best in a morning, iii. 2. 1. 5. Diarrhoea, vi. 2. 3. Digestion injured by cold, iii. 2. 1. ---- increased by cold, vii. 2. 3. Digitalis, iv. 2. 3. 7. v. 2. 1. 2. ---- tincture of, iv. 2. 3. 7. Dragon's blood, iv. 3. 5. 2. Dropsy, iv. 2. 3. 4. iv. 2. 6. 7. E. Ears, eruption behind, iv. 2. 9. 2. Earth of bones, iv. 2. 5. ---- of alum, vi. 2. 4. ---- calcareous, iv. 2. 5. 3. vi. 2. 4. i. 2. 4. 3. Eggs, i. 2. 1. 4. Egg-shells diuretic, iii. 2. 4. Electricity, ii. 2. 2. 2. iv. 2. 9. Emetics, how they act, v. 2. 1. Errhines mild, iii. 2. 9. ---- in hydrocephalus, v. 2. 3. 1. ---- violent, v. 2. 3. ---- in head-ach, v. 2. 3. 1. Erysipelas, iv. 2. 9. Essential oils, ii. 2. 3. Ether, vitriolic, ii. 2. 3. iii. 3. 1. vi. 3. 1. 3. ---- in ascarides, vii. 1. 2. Etiolation, i. 2. 3. 4. Euphorbium, v. 3. 3. Exercise, iii. 3. 1. 6. ii. 2. 6. Eyes inflamed, ii. 2. 2. 2. iv. 2. 4. 3. F. Famine, times of, i. 2. 3. 5. and 6. Fear, v. 2. 4. Feathers, smoke of, vi. 3. 1. 6. Fennel, iii. 3. 4. 4. Ferula asafoetida, iii. 3. 3. Fish, i. 2. 1. 2. i. 2. 1. 5. Flannel shirt, ii. 2. 2. 1. Flesh of animals, i. 2. 1. Fluke-worm, iv. 2. 6. Foxglove, iv. 2. 3. 7. v. 2. 1. v. 2. 4. ---- tincture of, iv. 2. 3. 7. Friction, ii. 2. 6. iii. 3. 1. 6. G. Galanthus nivalis, vii. 3. 3. Galbanum, vi. 3. 1. Gall-stones, iv. 2. 6. Galls of oak, iv. 3. 5. Garlic, iii. 3. 3. Gentiana centaurium, iv. 3. 3. ---- lutea, iv. 3. 3. Ginger, iii. 3. 1. iii. 3. 4. Gonorrhoea, iv. 2. 2. iii. 2. 4. Gout, iv. 2. 11. 2. Guaiacum, iii. 3. 1. Gum arabic, iii. 3. 3. 3. ---- tragacanth, iii. 3. 3. 3. Glycyrrhiza glabra, iii. 3. 3. 3. Gravel, v. 2. 4. 4. H. Hartshorn, spirit and salt of, iii. 3. 3. iii. 3. 1. vi. 3. 1. 4. ---- calcined, iv. 2. 5. vi. 2. 3. Hæmorrhages, iv. 2. 4. 4. iv. 2. 6. 2. Hæmatoxylon campechianum, iv. 3. 5. 2. Hay, infusion of, i. 2. 3. 6. Head-ach, snuff in, v. 2. 3. 1. Heat, ii. 2. 2. 1. See Bath. ---- an universal solvent, vii. 2. 2. Helenium, iii. 3. 3. 2. Herpes, iv. 2. 1. iv. 2. 9. Herrings, red, iii. 3. 1. 4. Honey, iii. 3. 3. 3. iii. 3. 5. 1. Hop in beer, why noxious, iv. 2. 3. 6. iv. 2. 11. 2. Hordeum distichon, iii. 3. 3. 3. Humulus lupulus, iv. 2. 3. iv. 2. 11. Hydrargyrus vitriolatus, v. 2. 3. Hysteric disease, vi. 2. 1. ---- pains, vi. 2. 1. ---- convulsions, vi. 2. 1. I. Jalapium, iii. 3. 5. 5. Japan earth, iv. 3. 5. 2. Jaundice, iv. 2. 6. 3. Ileus, vi. 2. 5. Incitantia, ii. Intermittents. See Agues. Inverted motions, vi. 2. 1. ---- in hysteric disease, vi. 2. 1. ---- of the stomach, vi. 2. 2. ---- intestinal canal, vi. 2. 5. ---- of lymphatics, vi. 2. 3. Inula helenium, iii. 3. 3. 2. Ipecacuanha, v. 2. 1. Iron, rust of, iv. 3. 6. Irritability prevented, iv. 2. 3. 3. Itch, iv. 2. 1. 3. L. Laurus camphora, iii. 3. 1. ---- cinnamomum, iii. 3. 1. ---- sassafras, iii. 3. 1. Lead, iv. 3. 6. ---- colic from, v. 2. 2. 2. ---- sugar of, iv. 2. 9. Leeks, iii. 3. 3. 1. Legs, ulcers of, iv. 2. 10. Lemon-juice, iv. 2. 1. iv. 2. 2. Leontodon taraxacum, iv. 3. 4. Life shortened by great stimulus, i. 1. Lime, i. 2. 4. 3. Liquorice, iii. 3. 3. 3. Liver inflamed, iv. 2. 6. Logwood, iv. 3. 5. 2. Lymphatics, inverted motions of, v. 2. 1. M. Magnesia alba, iii. 3. 5. 3. Malt, i. 2. 3. 5. Manna, iii. 3. 5. Marsh-mallows, iii. 3. 3. 3. Marjoram, iii. 3. 9. Marum, iii. 3. 9. Mastich, iii. 3. 2. iii. 3. 3. Menianthes trifoliata, iv. 3. 3. Menispermum cocculus, ii. 3. 1. Menstruation promoted, iv. 2. 6. 6. ---- repressed, iv. 2. 6. 6. Mercury, iii. 3. 2. vi. 2. 2. ---- preparations of, iv. 3. 7. iv. 2. 7. iv. 2. 9. ---- injected as a clyster, vi. 3. 5. Metallic salts, iv. 2. 6. Milk, i. 2. 2. Mimosa nilotica, iii. 3. 3. 3. ---- catechu, iv. 3. 5. 2. Mint, vi. 3. 1. 3. Mortification, iv. 2. 9. Mucilage, vegetable, vii. 3. 3. Mucus, animal, vii. 3. 5. Mushrooms, i. 2. 1. 2. Musk, vi. 2. 1. vi. 3. 1. Mustard, iv. 3. 4. See Sinapism. N. Nausea in fevers, vii. 2. 5. Neutral salts diuretic, why, iii. 2. 4. ---- increase some coughs, iii. 2. 4. ---- increase heat of urine, iii. 2. 4. Nicotiana tabacum, iii. 3. 9. ii. 3. 1. Nitre, iii. 3. 4. v. 2. 4. Nutmeg, iii. 2. 1. Nutrientia, i. O. Oil of almonds, iii. 3. 5. 4. ---- in cream, i. 2. 3. 2. ---- of amber, vi. 2. 1. ---- expressed externally, iii. 2. 3. ---- essential, ii. 2. 3. iii. 3. 1. 2. Oiled silk, vii. 3. 13. Oleum, animale, vi. 2. 1. vi. 3. 4. ---- ricini, iii. 3. 5. 4. Onions, iii. 3. 3. Opium, ii. 2. 1. 2. iv. 1. 2. ---- in nervous pains, ii. 2. 1. 5. ---- in inflammatory pains, ii. 2. 1. 6. ---- increases all secretions and absorptions, ii. 2. 1. 1. ---- absorption after evacuation, iv. 2. 8. 2. ii. 2. 1. 3. ---- stops sweats, iv. 2. 1. 2. ---- intoxicates, ii. 2. 1. 1. Oranges, their peel, iv. 3. 3. Orchis, vii. 3. 3. Oxygen gas, ii. 2. 4. i. 2. 5. iii. 2. 11. iv. 1. 4. ---- produces and heals ulcers, iv. 2. 7. P. Papin's digester, i. 2. 3. 5. Papaver somniferum, ii. 3. 1. iv. 3. 2. See Opium. Pains, periodic, cured by opium, ii. 2. 1. Pareira brava, iii. 3. 4. 4. Parsley, iii. 3. 4. Passions, ii. 2. 5. Pasturage, i. 2. 3. 7. Pepper, iii. 3. 1. Peripneumony, iv. 2. 8. 2. Perspiration in a morning, iii. 2. 1. ---- not an excrement, iii. 2. 1. Peru, balsam of, iii. 3. 5. 4. Petechiæ, iv. 2. 4. 2. Pimento, iii. 3. 1. Piper indicum, iii. 3. 1. Pistacia lentiscus, iii. 3. 2. Pix liquida, iii. 3. 3. Plaster-bandage, iv. 2. 10. Pleurisy, iv. 2. 8. 2. Polygala seneka, iii. 3. 3. 2. Poppy. See Papaver. Portland's powder noxious, why, iv. 2. 11. 2. Potatoe-bread, i. 2. 3. 4. Potentilla, iv. 3. 5. Prunes, iii. 3. 5. 1. Prunus domestica, iii. 3. 5. 1. ---- spinosa, iv. 3. 1. ---- lauro-cerasus, ii. 3. 1. Pulegium, vi. 3. 1. 3. Pulse, intermittent, relieved by arsenic, iv. 2. 6. Pyrethrum, iii. 3. 2. Pyrus malus, vii. ---- cydonia, iv. 3. 1. Q. Quassia, iv. 2. 2. Quince, iv. 3. 1. Quinquefolium, iv. 3. 5. R. Ratafie, why destructive, ii. 2. 1. Resin diuretic, iii. 2. 4. vi. 2. 4. Rhamnus catharticus, v. 3. 2. Rheumatism, iv. 2. 4. 5. iv. 2. 10. 2. Rheum palmatum. See Rhubarb. Rhubarb, iii. 2. 1. iv. 2. 5. 1. iii. 3. 5. 5. ---- causes constipation, why, iii. 2. 1. 1. Rice, vii. Roses, iv. 3. 5. Rot in sheep, iv. 2. 6. S. Sago, vii. 3. Sagopænum, vi. 3. 1. Salivation not necessary, iv. 2. 7. ---- hysteric, v. 2. 3. Salt, common, unwholesome, iii. 1. 12. ---- muriatic, iii. 3. 1. ---- in clysters, iii. 2. 7. Salts, why diuretic, iii. 2. 4. ---- neutral, iii. 3. 5. 3. iii. 2. 4. ---- improper in coughs and gonorrhoea, iii. 2. 4. Salt fish and salt meat increase perspiration, iii. 2. 1. Sassafras, iii. 3. 1. Scammony, v. 2. 2. Scarcity, times of, i. 2. 3. 5. and 6. Scilla maritima, v. 2. 2. iv. 2. 3. iii. 3. 3. v. 2. 3. Scorbutic legs, iv. 2. 10. Scrophulous tumours, ii. 2. 4. iv. 2. 9. Sea-water, iii. 3. 5. 3. Secernentia, iii. Secretion of the bladder, iii. 2. 6. ---- of the rectum, iii. 2. 7. ---- of the skin, iii. 2. 8. Seneka, iii. 3. 3. 2. Senna, iii. 3. 5. 5. Serpentaria virginiana, iii. 3. 1. Sialagogues, iii. 2. 2. v. 2. 3. Simarouba, iv. 3. 5. Sinapi, iv. 3. 4. Sinapisms, vi. 2. 2. iii. 2. 8. vi. 2. 2. Sisymbrium nasturtium, iv. 3. 4. Sloes, iv. 2. 2. Snuffs of candles, vi. 3. 1. 4. Society, i. 2. 3. 7. Soot, vi. 3. 1. 4. Sorbentia, various kinds, iv. 2. 1. Spasmodic doctrine exploded, vii. 2. 3. Spermaceti, iii. 3. 3. 3. Spice noxious, iii. 1. 12. Spirit of wine noxious, ii. 2. 1. Sponge, burnt, vi. 3. 1. 4. Squill. See Scilla. Starch, i. 2. 3. 1. ---- from poisonous roots, i. 2. 3. 4. Steam, bath of, iv. 2. 3. 8. Steel, iv. 2. 6. ---- forwards and represses menstruation, iv. 2. 6. Stizolobium siliqua hirsuta, iii. 3. 2. vii. 3. 11. Strychnos nux vomica, ii. 3. 1. Sublimate of mercury, iv. 2. 7. iv. 2. 9. Sugar nourishing, i. 2. 3. 1. and 5. iii. 3. 3. 3. ---- formed after the death of the plant, i. 2. 3. 5. ---- aperient, iii. 3. 5. 1. Sulphur, iii. 3. 5. 4. Sweats in a morning, iii. 2. 1. 5. ---- on waking, iii. 2. 1. 5. ---- cold, v. 2. 5. ---- stopped by opium, iv. 2. 1. 2. T. Tænia, vermes. See Worms. Tamarinds, iii. 3. 5. 1. Tansey, tanacetum, iv. 3. 3. Tar, iii. 3. 3. Tartar, crystals of, iii. 3. 5. 1. Class i. 2. 3. 13. ---- vitriolate, iii. 3. 5. 3. ---- emetic, v. 2. 1. v. 2. 2. Tea, vii. 2. 1. Tears, iii. 2. 10. Testaceous powders, iv. 2. 1. Tetradynamia, plants of, iv. 2. 4. Tincture of digitalis, iv. 2. Tinea, herpes, iv. 2. 1. 4. Tobacco, ii. 3. 1. iii. 3. 9. iv. 2. 3. 7. ---- injures digestion, iii. 2. 2. 3. Tolu balsam, iii. 3. 3. Tormentilla erecta, iv. 3. 5. Torpentia, vii. Tragacanth gum, iii. 3. 3. 3. Turpentine, vi. 2. 4. ---- spirit of, iii. 2. 6. Turpeth mineral, v. 2. 3. Tussilago farfara, iii. 3. 3. 3. U. Ulcers, scrophulous, iv. 2. 9. ---- of the mouth, iv. 2. 2. ---- cured by absorption, ii. 2. 1. 4. iv. 2. 3. 5. Uva ursi, iv. 3. 5. V. Valerian, vi. 3. 1. Vegetable acids, iv. 2. 1. ---- food, i. 2. 1. 2. Venereal ulcers, iv. 2. 7. Venesection, vii. 2. 4. iv. 2. 8. ---- diminishes secretions, vii. 2. 4. ---- increases absorptions, vii. 2. 4. Veratrum, v. 3. 2. Vibices, iv. 2. 4. 3. Vinegar, iv. 2. 1. 2. iv. 2. 4. 3. ii. 2. 1. 9. Vitriol blue in agues, iv. 2. 6. iv. 2. 2. ---- in ulcers, iv. 2. 9. ---- white, iv. 3. 6. v. 2. 1. ---- acid of, iv. 2. 1. ---- in sweats, iv. 1. 1. ---- in small-pox, iv. 1. 1. Volatile salt, vi. 3. 1. 6. Vomiting, v. 2. 2. Vomiting stopped by mercury, vi. 2. 2. Vomits, iv. 2. 3. 7. W. Warm bath, ii. 2. 2. 1. ---- in diabetes vi. 2. 4. Water, i. 2. 4. ---- dilutes and lubricates, vii. 2. 2. ---- cold, produces sweats, iii. 2. 1. ---- iced, in ileus, vi. 2. 5. ---- cresses, iv. 3. 4. Whey of milk, iii. 3. 5. 2. i. 2. 2. 2. Wine, ii. 3. 1. Worms, vii. 1. 2. iii. 2. 7. iv. 2. 6. 4. ---- in sheep, iv. 2. 6. 4. Z. Zinc, vitriol of, v. 3. 1. THE END. * * * * * Corrections made to printed original. Species list for I. 2. 5.: "Tactus imminutus.": 'Tactu, imminutus' in original (compare main text). I. 1. 4. 1. "Nictitatio irritativa": 'Nectitatio' in original (compare contents list). I. 1. 5. 8. "Perpetual sneezings in the measles": 'sneeezings' in original. I. 2. 1. 11. "the periodical venereal orgasm of the female quadrupeds": 'quadupeds' in original. I. 2. 3. 1. "Mucus faucium frigidus": 'fancium' in original (compare contents list). I. 3. 1. 1. "the retrograde motions of the oesophagus": 'retograde' in original. Genus list for II. 3. Original reads 1. Of the arterial system. 2. Of the absorbent system. 3. Of the excretory ducts. - the first two genera do not appear in the species lists or the main text, with "Of the excretory ducts." appearing there as 1. Species list for II. 1. 3.: "Peripneumonia superficialis": 'superficialie' in original (compare main text). Species list for II. 1. 4.: "11. Fistula urethræ." Entry missing in original and subsequent entries wrongly numbered. Species list for II. 1. 6.: "Febris a pure clauso.": 'clanso' in original (compare main text). Species list for II. 1. 7.: "Rubor jucunditatis": 'jucunditalis' in original (compare main text). II. 1. 3. 5. "Raucedo catarrhalis.": 'Rancedo' in original. II. 1. 4. 11. "The perpetual use of bougies, either of catgut or of caoutchouc": 'coartchouc' in original. The same error occurs in III. 1. 1. 15. II. 1. 5. 6. "Psora": 'Psory' in original (compare contents list & index). Species list for III. 1. 2.: "Superstitious hope": 'Supestitious' in original (compare main text). III. 1. 1. 9. "Assafoetida": 'Assafætida' in original. III. 1. 2. 12. "Pulchritudinis desiderium.": 'Pulchitudinis' in original (compare contents list). III. 1. 2. 12. "a medical person in good circumstances": 'cir-circumstances' over line break in original. III. 1. 2. 24. "See Botanic Garden, P. I. Cant. I. l. 278.": 'Botannic' in original. Species list for IV. 2. 2. "Dolor humeri in hepatitide": 'hepatidide' in original. So in text IV. 2. 2. 9.: in index 'hepatidite'. IV. 2. 1. 4. "the capillaries of the stomach and the cutaneous ones": 'cataneous' in original. SUPPLEMENT TO CLASS IV. XII. 11. Ninthly. "the sensorial power of irritation": 'iritation' in original. ibid. "the vertigo eases for a few minutes.": 'cases' (for 'eases') in original. XIII. "once rather delirious": 'delious' in original. XVI. 7. 8. "The urine is pale and in small quantity": 'quanity' in original. INDEX TO CLASSES: "Fever puerperal": 'perpetual' in original. "Suggestion, slow," gives no section number & does not seem to exist. ARTICLES OF THE MATERIA MEDICA: II. 2. 1. 5. "epilepsia dolorifica": 'dolorofica' in original. II. 3. 1. "Strychnos nux vomica": 'nuc' in original. VI. 2. 4. "The diabætes consists": 'diaboetes' in original. V. 3. 3. "hydrargyrus": 'hydragyrus' in original. VII. 2. Article "II." was numbered 'II. 2.', and "III. 1." was numbered 'III. 3. 1.'. Corrected cross references. In SECTION Printed reference Corrected to I. 1. 2. 3. Art. III. 2. 12. (no correction) I. 1. 5. 8. Class II. 1. 1. 2. II. 1. 1. 3. I. 2. 1. 2. Class IV. 1. 2. 6. IV. 2. 1. 16. I. 2. 2. 2. Class II. 3. 1. 1. (no correction) (see Genus list for II. 3.) I. 2. 3. 11. Class I. 2. 3. 16. I. 2. 3. 17. I. 2. 4. 11 Class IV. 1. 2. 11. IV. 2. 2. 7. (first) ibid. Class IV. 2. 1. 7. IV. 2. 2. 7. (second) I. 2. 4. 15. Class II. 1. 2. 13. II. 1. 2. 18. I. 2. 5. 1. Class I. 2. 3. 26. (no correction) ibid. Class I. 2. 3. 25. (no correction) I. 3. 1. 3. Class II. 1. 4. 7. II. 1. 4. 6. I. 3. 1. 5. Class III. 1. 1. 15. III. 1. 1. 14. I. 3. 1. 7. Class I. 3. 1. 9. I. 3. 1. 10. I. 3. 1. 11. Class IV. 2. 1. 7. IV. 1. 2. 7. II. 1. 2. 2. Class II. 1. 5. 3. II. 1. 4. 1. II. 1. 2. 12. Class II. 1. 4. 11. II. 1. 4. 12. II. 1. 3. 3. Class II. 2. 2. 1. (no correction) ibid. Class II. 1. 2. 1. II. 1. 3. 1. II. 1. 3. 17. Class I. 2. 1. 14. I. 2. 1. 15. ibid. Class IV. 2. 1. 16. IV. 1. 2. 16. II. 1. 4. 5. Class II. 1. 5. 1. II. 1. 5. 2. II. 1. 4. 8. Class II. 1. 4. 10. (no correction) II. 1. 4. 17. Class I. 2. 2. 12. I. 2. 2. 14. II. 1. 6. 8. Class II. 1. 4. 12. II. 1. 4. 13. II. 1. 7. 1. Class I. 1. 5. 12. I. 1. 5. 11. II. 2. 2. 1. Class I. 1. 4. 4. I. 2. 4. 12. III. 1. 1. 5. Class IV. 3. 2. 2. IV. 1. 3. 2. III. 1. 2. Sect. XXXV. 1. 13. XXXV. 1. 3. III. 1. 2. 2. Class I. 1. 1. 9. III. 1. 1. 9. III. 1. 2. 10. Class IV. 2. 1. 9. (no correction) III. 1. 2. 14. Class I. 2. 3. 9. I. 2. 4. 10. III. 2. 1. 2. Class IV. 3. 2. 2. IV. 1. 3. 2. III. 2. 1. 4. Class IV. 2. 2. 10. IV. 1. 2. 10. IV. 1. 1. C. Class IV. 1. 4. 6 IV. 1. 4. 5. (2nd time.) In INDEX OF CLASSES: Ascarides iv. 2. 1. 9. iv. 1. 2. 9. Azote i. 11. 4. i. 11. 6. Calculi renis iv. 2. 3. 3. (no correction) Catamenia i. 2. 1. 10. i. 2. 1. 11. Consternation i. 1. 5. 12. i. 1. 5. 11. Constipation ii. 2. 1. 7. ii. 2. 2. 7. Costiveness ii. 2. 1. 7. ii. 2. 2. 7. Diarrhoea rheumatic iv. 2. 1. 16. iv. 1. 2. 16. Digestion decreased ... iv. 1. 2. 5 iv. 2. 1. 6. Dilirium in parotitis iv. 2. 1. 19 iv. 1. 2. 19. Dyspnoea rheumatica iv. 2. 1. 16. iv. 1. 2. 16. Eruption of small-pox iv. 2. 1. 12. iv. 1. 2. 12. Fear, abortion from iv. 1. 3. 7. iv. 3. 1. 7. ---- paleness in iv. 1. 3. 5. iv. 3. 1. 5. Fever sensitive ii. 1. 5. 1. ii. 1. 6. 1. ---- return of cold fit Suppl. i. 3. Suppl. i. 4. Frigus chronicum i. 2. 2. 2. i. 2. 2. 1. Gangreen ii. 1. 6. 17. (no correction) Hoarseness iii. 2. 1. 4. iii. 2. 1. 5. Hydatides in calves i. 2. 5. 2. i. 2. 5. 4. Hydrogene gas i. 11. 4. i. 11. 6. Hysteria from cold iv. 3. 3. 3. iv. 3. 4. 3. Inflammation ... bowels ii. 1. 2. 3. ii. 1. 2. 11. Lingua arida iv. 2. 4. 11. (no correction) Lochia nimia i. 2. i. 2. 1. 13. Lues venerea ii. 1. 5. 8. ii. 1. 5. 2. Maculæ vultus i. 2. 1. 9. i. 2. 2. 10. Mammarum tumor iv. 2. 1. 19. iv. 1. 2. 19. Mammularum tensio iv. 2. 1. 6. iv. 1. 2. 6. Mercury in vertigo iv. 1. 2. 11. iv. 2. 1. 11. Nipples, tension of iv. 2. 1. 6. iv. 1. 2. 6. Paresis sensitiva i. 2. 1. 3. ii. 2. 1. 3. Pubis and throat ... iv. 2. 1. 7. iv. 1. 2. 7. Respiration quick ... ii. 1. 1. 3. ii. 1. 1. 4. Setons ii. 1. 6. ii. 1. 6. 6. Sickness cured by warm iv. 1. 2. 2. iv. 1. 1. 2. Splenitis ii. 2. 2. 13. ii. 1. 2. 13. Sternutatio a lumine iv. 2. 1. 2. iv. 1. 2. 2. Stocks for children ii. 2. 2. 17. i. 2. 2. 17. Surprise i. 1. 5. 12. i. 1. 5. 11. Sympathy throat & pubis iv. 2. 1. 7. iv. 1. 2. 7. Tears sympathetic iii. 1. 1. 10. iii. 1. 2. 10. Tinnitus aurium iv. 1. 1. 15. iv. 2. 1. 15. Torpor of the liver i. 1. 2. 6. i. 2. 2. 6. Tremor of anger iv. 3. 1. 4 iv. 2. 3. 4. ---- of fear iv. 1. 2. 5. iv. 3. 1. 5. Tussis hepatica iv. 1. 2. 7. iv. 2. 1. 8. ---- arthritica iv. 1. 2. 8. iv. 2. 1. 9. ---- periodica iv. 1. 2. 9. iv. 3. 4. 2. ---- a pedibus frigidis iv. 1. 2. 6. iv. 2. 1. 7. Ulcers of the legs ii. 1. 4. 13. ii. 1. 4. 14. Variola eruption of iv. 2. 1. 12. iv. 1. 2. 12. Vertigo with vomiting iv. 2. 3. 2. iv. 3. 2. 3. Watchfulness iv. 3. 2. 5. iv. 1. 3. 6. Winking iv. 3. 2. 2. iv. 1. 3. 2. Womb, inflammation of ii. 1. 8. 16. ii. 1. 2. 16. In ARTICLES OF THE MATERIA MEDICA: II. 2. 1. 5. Class III. 1. 1. 12. III. 1. 1. 13. IV. 2. 3. 8. Class IV. 2. 2. 1. Art. II. 2. 2. 1. IV. 2. 6. 5. Sect. XXX. 4. XXX. 1. 4. V. 2. 1. 4. Art. II. 3. 7. IV. 2. 3. 7. VI. 2. 2. Class IV. 1. 1. 3. IV. 1. 1. 2. INDEX OF THE ARTICLES Acacia iv. 2. 5. 2. iv. 3. 5. 2. Alcali vol. iii. 3. 3. iii. 3. 8. Althæa iii. 2. 3. 3. iii. 3. 3. 3. Aloe iii. 2. 5. 5. iii. 3. 5. 5. Alum iv. 2. 1. iv. 2. 2. Amalgama in worms vii. 2. 2. vii. 1. 2. Amber, oil of vi. 3. 4. vi. 3. 1. 4. Ammoniac salt iii. 3. 3. iii. 3. 1. 3. Anchovy iii. 2. 1. 4. iii. 3. 1. 4. Antimony prepared iii. 2. 1. 5. iii. 3. 1. 5. Apium, petroselinum iii. 2. 4. 4. iii. 3. 4. 4. Armenian bole vi. 3. 5. 3. iv. 3. 5. 3. Asa foetida ii. 3. iii. 3. Ascarides iii. 2. 9. 7. iii. 2. 7. Asparagus iii. 2. 4. 4. iii. 3. 4. 4. Astragalus tragacanth iii. 2. 3. 3. iii. 3. 3. 3. Barley iii. 2. 3. 3. iii. 3. 3. 3. Bath, warm iii. 2. 1. 6. iii. 3. 1. 6. ibid. iii. 2. 3. 4. iii. 3. 3. 4. Bile of animals iii. 2. 5. 2. iii. 3. 5. 2. Blood, transfusion of i. 2. 6. 2. i. 2. 6. 3. Bryony as a blister iii. 2. 9. iii. 2. 8. Cassia sistul iii. 2. 5. 1. iii. 3. 5. 1. ---- senna iii. 2. 5. 5. iii. 3. 5. 5. Chalybeates iv. 2. 4. 2. iv. 3. 4. 2. Cinnamon iii. 3. 2. iii. 3. 1. 2. Cold, interrupted iii. 2. 1. 7. iii. 3. 1. 7. Copaiva balsam iii. 2. 4. 3. iii. 3. 4. 3. Daucus sylvestris iii. 2. 4. 4. iii. 3. 4. 4. Dragon's blood iv. 2. 5. 2. iv. 3. 5. 2. Ether, vitriolic vi. 3. 3. vi. 3. 1. 3. Exercise iii. 2. 1. 6. iii. 3. 1. 6. Eyes inflamed iv. 2. 3. iv. 2. 4. 3. Feathers, smoke of vi. 3. 6. vi. 3. 1. 6. Fennel iii. 2. 4. 4. iii. 3. 4. 4. Friction ii. 2. 5. ii. 2. 6. ibid. iii. 2. 1. 6. iii. 3. 1. 6. Ginger iii. 3. 4. (no correction) Gum arabic iii. 2. 3. 3. iii. 3. 3. 3. ---- tragacanth iii. 2. 3. 3. iii. 3. 3. 3. Glycyrrhiza glabra iii. 2. 3. 3. iii. 3. 3. 3. Hæmatoxylon camp... iv. 2. 5. 2. iv. 3. 5. 2. Hartshorn, spirit ... iii. 3. 3. (no correction) ibid. vi. 3. 4. vi. 3. 1. 4. Helenium iii. 2. 3. 2. iii. 3. 3. 2. Herrings, red iii. 2. 1. 4. iii. 3. 1. 4. Honey iii. 2. 3. 3. iii. 3. 3. 3. ibid. iii. 2. 5. 1. iii. 3. 5. 1. Hordeum distichon iii. 2. 3. 3. iii. 3. 3. 3. Jalapium iii. 2. 5. 5. iii. 3. 5. 5. Japan earth iv. 2. 5. 2. iv. 3. 5. 2. Inula helenium iii. 2. 3. 2. iii. 3. 3. 2. Leeks iii. 2. 3. 1. iii. 3. 3. 1. Liquorice iii. 2. 3. 3 iii. 3. 3. 3. Logwood iii. 2. 5. 2. iv. 3. 5. 2. Magnesia alba iii. 2. 5. 3. iii. 3. 5. 3. Marsh-mallows iii. 2. 3. 3. iii. 3. 3. 3. Mastich iii. 3. 3. (no correction) Mimosa nilotica iii. 2. 3. 3. iii. 3. 3. 3. ---- catechu iv. 2. 5. 2. iv. 3. 5. 2. Mint vi. 3. 3. vi. 3. 1. 3. Oil essential iii. 3. 2. iii. 3. 1. 2. Oleum, ricini iii. 2. 5. 4. iii. 3. 5. 4. Pareira brava iii. 2. 4. 4. iii. 3. 4. 4. Peru, balsam of iii. 2. 5. 4. iii. 3. 5. 4. Pix liquida iii. 3. 2. iii. 3. 3. Prunes iii. 2. 5. 1. iii. 3. 5. 1. Prunus domestica iii. 2. 5. 1. iii. 3. 5. 1. Pulegium vi. 3. 3. vi. 3. 1. 3. Rhubarb iii. 2. 5. 5. iii. 3. 5. 5. Salts, neutral iii. 2. 5. 3. iii. 3. 5. 3. Sea-water iii. 2. 5. 3. iii. 3. 5. 3. Seneka iii. 2. 3. 2. iii. 3. 3. 2. Senna iii. 2. 5. 5. iii. 3. 5. 5. Snuffs of candles vi. 3. 4. vi. 3. 1. 4. Soot vi. 3. 4. vi. 3. 1. 4. Spermaceti iii. 2. 3. 3. iii. 3. 3. 3. Sponge, burnt vi. 3. 4. vi. 3. 1. 4. Sugar nourishing iii. 2. 4. 3. iii. 3. 3. 3. ---- aperient iii. 2. 5. 1. iii. 3. 5. 1. Sulphur iii. 2. 5. 4. iii. 3. 5. 4. Sweats in a morning iii. 2. 1. 1. iii. 2. 1. 5. ---- on waking iii. 2. 1. 1. iii. 2. 1. 5. Tamarinds iii. 2. 5. 1. iii. 3. 5. 1. Tartar, crystals of iii. 2. 5. 1. iii. 3. 5. 1. ---- vitriolate iii. 2. 5. 3. iii. 3. 5. 3. Testaceous powders iv. 2. 2. iv. 2. 1. Tobacco iv. 2. 3. 8. iv. 2. 3. 7. Tragacanth gum iii. 2. 3. 3. iii. 3. 3. 3. Tussilago farfara iii. 2. 3. 3. iii. 3. 3. 3. Valerian vi. 3. 3. vi. 3. 1. Vinegar iv. 2. 1. 9. iv. 2. 1. 2. Volatile salt vi. 3. 6. vi. 3. 1. 6. Whey of milk iii. 2. 5. 2. iii. 3. 5. 2.